Psoriasis

Psoriasis is a chronic autoimmune skin disease affecting approximately 6.7 million adults in the United States.¹ Although its pathogenesis is not yet clear, risk factors and triggers provide insight into potential pathways by which psoriasis can occur. There is notable overlap between risk factors and triggers of psoriasis; perceived risk factors might, in fact, be triggers causing manifestation of disease in predisposed persons. In this review, we summarize the key factors contributing to onset and exacerbation of psoriasis. When learning to manage this chronic disease, it also may be helpful to educate patients about how these elements may affect the course of psoriasis.

Genetics

The pathogenesis of psoriasis has a strong genetic component, with approximately 70% and 20% concordance rates in monozygotic and dizygotic twins, respectively.² Moreover, studies have shown a positive family history in approximately 35% of patients.^3,4 Family-based studies have found a 50% risk of developing psoriasis in patients with 2 affected parents.⁵ However, the genetics of psoriasis are complex and are attributed to many different genes. Thus far, genes involving antigen presentation, T-cell receptor development and polarization, and the nuclear factor κβ (NF-κβ) pathway have been identified.⁶

HLA-Cw6
The most well-studied gene implicated in psoriasis is HLA-Cw6, which encodes a major histocompatibility complex class I allele supporting psoriasis as a T cell–mediated reaction to an autoantigen.⁶ Two potential antigens for HLA-Cw6 recently have been identified: LL-37, a cathelicidin-related antimicrobial peptide, and the A disintegrin and metalloproteinase with thrombospondin motifs-like protein 5 (ADAMTSL5), found on melanocytes and keratinocytes.⁷ The percentage of psoriasis patients with HLA-Cw6 ranges from 10.5% to 77.2%, with higher frequency in white individuals than in Asians.⁷

HLA-Cw6 manifests as specific features in psoriasis, including onset of disease before 21 years of age.⁸ It also is more strongly associated with guttate-type psoriasis, greater body surface area involvement, and higher incidence of Köbner phenomenon. Patients with positive HLA-Cw6 also reported worsening of psoriasis during and after throat infection.⁹

Caspase Recruitment Domain Family Member 14
Another gene mutation implicated in psoriasis pathogenesis is caspase recruitment domain family member 14, CARD14 (formerly PSORS2), a gene encoding a scaffolding protein important in the activation of NF-κβ.^10,11 Missense CARD14 mutations cause upregulation of NF-κβ through formation of a complex with adapter protein B-cell lymphoma 10 (BCL10) and mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT1),¹² which, in turn, causes increased transcription of cytokines IL-8, C-C motif chemokine ligand 20 (CCL-20), and IL-36 gamma in the keratinocyte.¹³ Mutations in CARD14 alone lead to psoriasiform skin in mice through amplified activation of the IL-23/IL-17 axis.^14,15 Patients with a mutation in a CARD14 variant (p.Arg820Trp) have demonstrated better response to tumor necrosis factor (TNF) inhibitors.¹⁶

Further characterization of the genetic pathogenesis of psoriasis might lead to better targeted therapies, including the possibility of MALT1 inhibitors as a treatment option.¹²

Infection

Streptococcus
The association between streptococcal infection and psoriasis was first documented more than 100 years ago, specifically the onset of acute guttate psoriasis.^17,18 Although classically described following throat infection, psoriasis also occurs following streptococcal vulvovaginitis and perianal streptococcal infection.^19,20

This type of psoriasis is typically self-limited but can recur with subsequent streptococcal infections or initiate a more chronic plaque psoriasis. Patients have a 1 in 3 risk of developing chronic psoriasis within 10 years of a single episode of acute guttate psoriasis.²¹ Moreover, in many patients with existing plaque psoriasis, throat infection exacerbates psoriatic symptoms.²² The mechanism of exacerbation is likely due to cross-reactivity between streptococcal M surface antigen and human keratinocytes and might also be influenced by inherited abnormalities in immune response.^23-26 Therefore, tonsillectomy has been studied as a possible treatment of psoriasis but is likely helpful only in patients with exacerbations of disease that are closely associated with recurrent tonsillitis.²⁷

Human Immunodeficiency Virus
The prevalence of psoriasis in human immunodeficiency virus (HIV) patients is similar to or greater than the general population.²⁸ Human immunodeficiency virus infection causes new onset of psoriasis and exacerbation of existing psoriasis; severity often is correlated with worsening immune function.^28,29

The clinical subtypes of psoriasis that occur most frequently with HIV include guttate, inverse, and erythrodermic, though patients may present with any subtype.²⁸ The mechanism is puzzling because HIV is primarily mediated by helper T cell 2 (T_H2) cytokines, whereas psoriasis is mainly driven by helper T cell 1 (T_H1) cytokines.³⁰ Furthermore, despite increased severity with lower CD4⁺ counts, treatments further lowering T-cell counts paradoxically improve symptoms.³¹ Current literature suggests that expansion of CD8⁺ memory T cells might be the primary mechanism in the exacerbation of psoriasis in HIV-mediated immunosuppression.³⁰

Treatment of HIV-associated psoriasis presents challenges because many therapeutics cause further immunosuppression. The National Psoriasis Foundation recommends topical preparations as first-line agents for mild to moderate psoriasis.³² For moderate to severe psoriasis, retroviral agents may be effective as first-line monotherapy or when supplemented by phototherapy with UVB or psoralen plus UVA. Retinoids can be used as second-line agents.³² For cases of severe refractory psoriasis, cyclosporine, methotrexate, TNF inhibitors, or hydroxyurea can be considered. There also is evidence that apremilast is effective without risk for worsening immune function.³³

Other Infections
Other bacteria associated with triggering or exacerbating psoriasis include Staphylococcus aureus and Helicobacter pylori.^34,35 Fungi, such as species of the genera Malassezia and Candida, and other viruses, including papillomaviruses and retroviruses, also have been implicated.³⁴

Medications

Numerous medications can trigger psoriasis, including lithium, nonsteroidal anti-inflammatory drugs, antimalarials, beta-blockers, and angiotensin-converting enzyme inhibitors.³⁴ More recent literature suggests that TNF inhibitors also can paradoxically induce psoriasis in rare cases.³⁵

Lithium
Psoriasis is the most common cutaneous adverse effect of lithium.³⁴ It is more likely to exacerbate existing disease but also can induce onset of psoriasis; it also can cause disease that is more refractory to treatment.^34,36 Current literature hypothesizes that lithium triggers psoriasis by interference of intracellular calcium channels through reduction of inositol, thereby affecting keratinocyte proliferation and differentiation.³⁴ Lithium also inhibits glycogen synthase kinase-3 (GSK-3), a serine threonine kinase, which, in turn, induces human keratinocyte proliferation.³⁷ However, it is unlikely lithium alone can induce psoriasis; genetic predisposition is necessary.

TNF Inhibitors
Tumor necrosis factor inhibitors such as adalimumab, etanercept, certolizumab pegol, golimumab, and infliximab are used in various inflammatory diseases, including psoriasis. Interestingly, there have been more than 200 reported cases of suspected TNF inhibitor–induced or –exacerbated psoriasis.³⁸ This phenomenon appears to occur more frequently with infliximab and is most likely to occur in the first year of treatment of Crohn disease and rheumatoid arthritis.³⁸ Plaque psoriasis is the most common form, but 15% to 26% of cases presented with 2 or more morphologies.^38,39

Treatment options include discontinuing therapy, though many patients experience resolution while continuing treatment or switching to another TNF inhibitor.^38-40 Traditional topical therapies also have been used with success.⁴⁰ The pathogenesis of this phenomenon is still unclear but is thought to involve both the IL-23/helper T cell 17 (T_H17) axis and dysregulation of IFN-α in the setting of TNF suppression.³⁸

Lifestyle

Obesity is a chronic low-grade inflammatory state that can contribute to the onset of psoriasis or exacerbation of existing disease.^41,42 Smoking also is thought to increase the risk for psoriasis, perhaps by a similar mechanism. Lee et al⁴³ found a strong positive correlation between the amount or duration of smoking and the incidence of psoriasis.

The relationship between psoriasis and alcohol consumption is less clear than it is between psoriasis and obesity or smoking; greater consumption is found in psoriasis patients, but evidence is insufficient to deem alcohol a risk factor.⁴⁴

Conclusion

Various factors, including genetics, infection, pharmacotherapeutic, and lifestyle, can all contribute to the induction or exacerbation of psoriasis. These factors can provide clues to the pathogenesis of psoriasis as well as help clinicians better counsel patients about their disease.

Psoriasis is a chronic autoimmune skin disease affecting approximately 6.7 million adults in the United States.¹ Although its pathogenesis is not yet clear, risk factors and triggers provide insight into potential pathways by which psoriasis can occur. There is notable overlap between risk factors and triggers of psoriasis; perceived risk factors might, in fact, be triggers causing manifestation of disease in predisposed persons. In this review, we summarize the key factors contributing to onset and exacerbation of psoriasis. When learning to manage this chronic disease, it also may be helpful to educate patients about how these elements may affect the course of psoriasis.

Genetics

The pathogenesis of psoriasis has a strong genetic component, with approximately 70% and 20% concordance rates in monozygotic and dizygotic twins, respectively.² Moreover, studies have shown a positive family history in approximately 35% of patients.^3,4 Family-based studies have found a 50% risk of developing psoriasis in patients with 2 affected parents.⁵ However, the genetics of psoriasis are complex and are attributed to many different genes. Thus far, genes involving antigen presentation, T-cell receptor development and polarization, and the nuclear factor κβ (NF-κβ) pathway have been identified.⁶

HLA-Cw6
The most well-studied gene implicated in psoriasis is HLA-Cw6, which encodes a major histocompatibility complex class I allele supporting psoriasis as a T cell–mediated reaction to an autoantigen.⁶ Two potential antigens for HLA-Cw6 recently have been identified: LL-37, a cathelicidin-related antimicrobial peptide, and the A disintegrin and metalloproteinase with thrombospondin motifs-like protein 5 (ADAMTSL5), found on melanocytes and keratinocytes.⁷ The percentage of psoriasis patients with HLA-Cw6 ranges from 10.5% to 77.2%, with higher frequency in white individuals than in Asians.⁷

HLA-Cw6 manifests as specific features in psoriasis, including onset of disease before 21 years of age.⁸ It also is more strongly associated with guttate-type psoriasis, greater body surface area involvement, and higher incidence of Köbner phenomenon. Patients with positive HLA-Cw6 also reported worsening of psoriasis during and after throat infection.⁹

Caspase Recruitment Domain Family Member 14
Another gene mutation implicated in psoriasis pathogenesis is caspase recruitment domain family member 14, CARD14 (formerly PSORS2), a gene encoding a scaffolding protein important in the activation of NF-κβ.^10,11 Missense CARD14 mutations cause upregulation of NF-κβ through formation of a complex with adapter protein B-cell lymphoma 10 (BCL10) and mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT1),¹² which, in turn, causes increased transcription of cytokines IL-8, C-C motif chemokine ligand 20 (CCL-20), and IL-36 gamma in the keratinocyte.¹³ Mutations in CARD14 alone lead to psoriasiform skin in mice through amplified activation of the IL-23/IL-17 axis.^14,15 Patients with a mutation in a CARD14 variant (p.Arg820Trp) have demonstrated better response to tumor necrosis factor (TNF) inhibitors.¹⁶

Further characterization of the genetic pathogenesis of psoriasis might lead to better targeted therapies, including the possibility of MALT1 inhibitors as a treatment option.¹²

Infection

Streptococcus
The association between streptococcal infection and psoriasis was first documented more than 100 years ago, specifically the onset of acute guttate psoriasis.^17,18 Although classically described following throat infection, psoriasis also occurs following streptococcal vulvovaginitis and perianal streptococcal infection.^19,20

This type of psoriasis is typically self-limited but can recur with subsequent streptococcal infections or initiate a more chronic plaque psoriasis. Patients have a 1 in 3 risk of developing chronic psoriasis within 10 years of a single episode of acute guttate psoriasis.²¹ Moreover, in many patients with existing plaque psoriasis, throat infection exacerbates psoriatic symptoms.²² The mechanism of exacerbation is likely due to cross-reactivity between streptococcal M surface antigen and human keratinocytes and might also be influenced by inherited abnormalities in immune response.^23-26 Therefore, tonsillectomy has been studied as a possible treatment of psoriasis but is likely helpful only in patients with exacerbations of disease that are closely associated with recurrent tonsillitis.²⁷

Human Immunodeficiency Virus
The prevalence of psoriasis in human immunodeficiency virus (HIV) patients is similar to or greater than the general population.²⁸ Human immunodeficiency virus infection causes new onset of psoriasis and exacerbation of existing psoriasis; severity often is correlated with worsening immune function.^28,29

The clinical subtypes of psoriasis that occur most frequently with HIV include guttate, inverse, and erythrodermic, though patients may present with any subtype.²⁸ The mechanism is puzzling because HIV is primarily mediated by helper T cell 2 (T_H2) cytokines, whereas psoriasis is mainly driven by helper T cell 1 (T_H1) cytokines.³⁰ Furthermore, despite increased severity with lower CD4⁺ counts, treatments further lowering T-cell counts paradoxically improve symptoms.³¹ Current literature suggests that expansion of CD8⁺ memory T cells might be the primary mechanism in the exacerbation of psoriasis in HIV-mediated immunosuppression.³⁰

Treatment of HIV-associated psoriasis presents challenges because many therapeutics cause further immunosuppression. The National Psoriasis Foundation recommends topical preparations as first-line agents for mild to moderate psoriasis.³² For moderate to severe psoriasis, retroviral agents may be effective as first-line monotherapy or when supplemented by phototherapy with UVB or psoralen plus UVA. Retinoids can be used as second-line agents.³² For cases of severe refractory psoriasis, cyclosporine, methotrexate, TNF inhibitors, or hydroxyurea can be considered. There also is evidence that apremilast is effective without risk for worsening immune function.³³

Other Infections
Other bacteria associated with triggering or exacerbating psoriasis include Staphylococcus aureus and Helicobacter pylori.^34,35 Fungi, such as species of the genera Malassezia and Candida, and other viruses, including papillomaviruses and retroviruses, also have been implicated.³⁴

Medications

Numerous medications can trigger psoriasis, including lithium, nonsteroidal anti-inflammatory drugs, antimalarials, beta-blockers, and angiotensin-converting enzyme inhibitors.³⁴ More recent literature suggests that TNF inhibitors also can paradoxically induce psoriasis in rare cases.³⁵

Lithium
Psoriasis is the most common cutaneous adverse effect of lithium.³⁴ It is more likely to exacerbate existing disease but also can induce onset of psoriasis; it also can cause disease that is more refractory to treatment.^34,36 Current literature hypothesizes that lithium triggers psoriasis by interference of intracellular calcium channels through reduction of inositol, thereby affecting keratinocyte proliferation and differentiation.³⁴ Lithium also inhibits glycogen synthase kinase-3 (GSK-3), a serine threonine kinase, which, in turn, induces human keratinocyte proliferation.³⁷ However, it is unlikely lithium alone can induce psoriasis; genetic predisposition is necessary.

TNF Inhibitors
Tumor necrosis factor inhibitors such as adalimumab, etanercept, certolizumab pegol, golimumab, and infliximab are used in various inflammatory diseases, including psoriasis. Interestingly, there have been more than 200 reported cases of suspected TNF inhibitor–induced or –exacerbated psoriasis.³⁸ This phenomenon appears to occur more frequently with infliximab and is most likely to occur in the first year of treatment of Crohn disease and rheumatoid arthritis.³⁸ Plaque psoriasis is the most common form, but 15% to 26% of cases presented with 2 or more morphologies.^38,39

Treatment options include discontinuing therapy, though many patients experience resolution while continuing treatment or switching to another TNF inhibitor.^38-40 Traditional topical therapies also have been used with success.⁴⁰ The pathogenesis of this phenomenon is still unclear but is thought to involve both the IL-23/helper T cell 17 (T_H17) axis and dysregulation of IFN-α in the setting of TNF suppression.³⁸

Lifestyle

Obesity is a chronic low-grade inflammatory state that can contribute to the onset of psoriasis or exacerbation of existing disease.^41,42 Smoking also is thought to increase the risk for psoriasis, perhaps by a similar mechanism. Lee et al⁴³ found a strong positive correlation between the amount or duration of smoking and the incidence of psoriasis.

The relationship between psoriasis and alcohol consumption is less clear than it is between psoriasis and obesity or smoking; greater consumption is found in psoriasis patients, but evidence is insufficient to deem alcohol a risk factor.⁴⁴

Conclusion

Various factors, including genetics, infection, pharmacotherapeutic, and lifestyle, can all contribute to the induction or exacerbation of psoriasis. These factors can provide clues to the pathogenesis of psoriasis as well as help clinicians better counsel patients about their disease.

Psoriasis is a chronic autoimmune skin disease affecting approximately 6.7 million adults in the United States.¹ Although its pathogenesis is not yet clear, risk factors and triggers provide insight into potential pathways by which psoriasis can occur. There is notable overlap between risk factors and triggers of psoriasis; perceived risk factors might, in fact, be triggers causing manifestation of disease in predisposed persons. In this review, we summarize the key factors contributing to onset and exacerbation of psoriasis. When learning to manage this chronic disease, it also may be helpful to educate patients about how these elements may affect the course of psoriasis.

Genetics

The pathogenesis of psoriasis has a strong genetic component, with approximately 70% and 20% concordance rates in monozygotic and dizygotic twins, respectively.² Moreover, studies have shown a positive family history in approximately 35% of patients.^3,4 Family-based studies have found a 50% risk of developing psoriasis in patients with 2 affected parents.⁵ However, the genetics of psoriasis are complex and are attributed to many different genes. Thus far, genes involving antigen presentation, T-cell receptor development and polarization, and the nuclear factor κβ (NF-κβ) pathway have been identified.⁶

HLA-Cw6
The most well-studied gene implicated in psoriasis is HLA-Cw6, which encodes a major histocompatibility complex class I allele supporting psoriasis as a T cell–mediated reaction to an autoantigen.⁶ Two potential antigens for HLA-Cw6 recently have been identified: LL-37, a cathelicidin-related antimicrobial peptide, and the A disintegrin and metalloproteinase with thrombospondin motifs-like protein 5 (ADAMTSL5), found on melanocytes and keratinocytes.⁷ The percentage of psoriasis patients with HLA-Cw6 ranges from 10.5% to 77.2%, with higher frequency in white individuals than in Asians.⁷

HLA-Cw6 manifests as specific features in psoriasis, including onset of disease before 21 years of age.⁸ It also is more strongly associated with guttate-type psoriasis, greater body surface area involvement, and higher incidence of Köbner phenomenon. Patients with positive HLA-Cw6 also reported worsening of psoriasis during and after throat infection.⁹

Caspase Recruitment Domain Family Member 14
Another gene mutation implicated in psoriasis pathogenesis is caspase recruitment domain family member 14, CARD14 (formerly PSORS2), a gene encoding a scaffolding protein important in the activation of NF-κβ.^10,11 Missense CARD14 mutations cause upregulation of NF-κβ through formation of a complex with adapter protein B-cell lymphoma 10 (BCL10) and mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT1),¹² which, in turn, causes increased transcription of cytokines IL-8, C-C motif chemokine ligand 20 (CCL-20), and IL-36 gamma in the keratinocyte.¹³ Mutations in CARD14 alone lead to psoriasiform skin in mice through amplified activation of the IL-23/IL-17 axis.^14,15 Patients with a mutation in a CARD14 variant (p.Arg820Trp) have demonstrated better response to tumor necrosis factor (TNF) inhibitors.¹⁶

Further characterization of the genetic pathogenesis of psoriasis might lead to better targeted therapies, including the possibility of MALT1 inhibitors as a treatment option.¹²

Infection

Streptococcus
The association between streptococcal infection and psoriasis was first documented more than 100 years ago, specifically the onset of acute guttate psoriasis.^17,18 Although classically described following throat infection, psoriasis also occurs following streptococcal vulvovaginitis and perianal streptococcal infection.^19,20

This type of psoriasis is typically self-limited but can recur with subsequent streptococcal infections or initiate a more chronic plaque psoriasis. Patients have a 1 in 3 risk of developing chronic psoriasis within 10 years of a single episode of acute guttate psoriasis.²¹ Moreover, in many patients with existing plaque psoriasis, throat infection exacerbates psoriatic symptoms.²² The mechanism of exacerbation is likely due to cross-reactivity between streptococcal M surface antigen and human keratinocytes and might also be influenced by inherited abnormalities in immune response.^23-26 Therefore, tonsillectomy has been studied as a possible treatment of psoriasis but is likely helpful only in patients with exacerbations of disease that are closely associated with recurrent tonsillitis.²⁷

Human Immunodeficiency Virus
The prevalence of psoriasis in human immunodeficiency virus (HIV) patients is similar to or greater than the general population.²⁸ Human immunodeficiency virus infection causes new onset of psoriasis and exacerbation of existing psoriasis; severity often is correlated with worsening immune function.^28,29

The clinical subtypes of psoriasis that occur most frequently with HIV include guttate, inverse, and erythrodermic, though patients may present with any subtype.²⁸ The mechanism is puzzling because HIV is primarily mediated by helper T cell 2 (T_H2) cytokines, whereas psoriasis is mainly driven by helper T cell 1 (T_H1) cytokines.³⁰ Furthermore, despite increased severity with lower CD4⁺ counts, treatments further lowering T-cell counts paradoxically improve symptoms.³¹ Current literature suggests that expansion of CD8⁺ memory T cells might be the primary mechanism in the exacerbation of psoriasis in HIV-mediated immunosuppression.³⁰

Treatment of HIV-associated psoriasis presents challenges because many therapeutics cause further immunosuppression. The National Psoriasis Foundation recommends topical preparations as first-line agents for mild to moderate psoriasis.³² For moderate to severe psoriasis, retroviral agents may be effective as first-line monotherapy or when supplemented by phototherapy with UVB or psoralen plus UVA. Retinoids can be used as second-line agents.³² For cases of severe refractory psoriasis, cyclosporine, methotrexate, TNF inhibitors, or hydroxyurea can be considered. There also is evidence that apremilast is effective without risk for worsening immune function.³³

Other Infections
Other bacteria associated with triggering or exacerbating psoriasis include Staphylococcus aureus and Helicobacter pylori.^34,35 Fungi, such as species of the genera Malassezia and Candida, and other viruses, including papillomaviruses and retroviruses, also have been implicated.³⁴

Medications

Numerous medications can trigger psoriasis, including lithium, nonsteroidal anti-inflammatory drugs, antimalarials, beta-blockers, and angiotensin-converting enzyme inhibitors.³⁴ More recent literature suggests that TNF inhibitors also can paradoxically induce psoriasis in rare cases.³⁵

Lithium
Psoriasis is the most common cutaneous adverse effect of lithium.³⁴ It is more likely to exacerbate existing disease but also can induce onset of psoriasis; it also can cause disease that is more refractory to treatment.^34,36 Current literature hypothesizes that lithium triggers psoriasis by interference of intracellular calcium channels through reduction of inositol, thereby affecting keratinocyte proliferation and differentiation.³⁴ Lithium also inhibits glycogen synthase kinase-3 (GSK-3), a serine threonine kinase, which, in turn, induces human keratinocyte proliferation.³⁷ However, it is unlikely lithium alone can induce psoriasis; genetic predisposition is necessary.

TNF Inhibitors
Tumor necrosis factor inhibitors such as adalimumab, etanercept, certolizumab pegol, golimumab, and infliximab are used in various inflammatory diseases, including psoriasis. Interestingly, there have been more than 200 reported cases of suspected TNF inhibitor–induced or –exacerbated psoriasis.³⁸ This phenomenon appears to occur more frequently with infliximab and is most likely to occur in the first year of treatment of Crohn disease and rheumatoid arthritis.³⁸ Plaque psoriasis is the most common form, but 15% to 26% of cases presented with 2 or more morphologies.^38,39

Treatment options include discontinuing therapy, though many patients experience resolution while continuing treatment or switching to another TNF inhibitor.^38-40 Traditional topical therapies also have been used with success.⁴⁰ The pathogenesis of this phenomenon is still unclear but is thought to involve both the IL-23/helper T cell 17 (T_H17) axis and dysregulation of IFN-α in the setting of TNF suppression.³⁸

Lifestyle

Obesity is a chronic low-grade inflammatory state that can contribute to the onset of psoriasis or exacerbation of existing disease.^41,42 Smoking also is thought to increase the risk for psoriasis, perhaps by a similar mechanism. Lee et al⁴³ found a strong positive correlation between the amount or duration of smoking and the incidence of psoriasis.

The relationship between psoriasis and alcohol consumption is less clear than it is between psoriasis and obesity or smoking; greater consumption is found in psoriasis patients, but evidence is insufficient to deem alcohol a risk factor.⁴⁴

Conclusion

Various factors, including genetics, infection, pharmacotherapeutic, and lifestyle, can all contribute to the induction or exacerbation of psoriasis. These factors can provide clues to the pathogenesis of psoriasis as well as help clinicians better counsel patients about their disease.

Psoriasis is a T cell–mediated inflammatory disease that manifests as erythematous scaling plaques of the skin. In recent decades, our understanding of psoriasis has transformed from a disease isolated to the skin to a systemic disease impacting the overall health of those affected.

With recent elucidation of the pathways driving psoriasis, development of targeted therapies has resulted in an influx of options to the market. Navigating the options can seem overwhelming even to the seasoned clinician. Becoming familiar with a sound treatment approach during residency will create a foundation for biologic use in psoriasis patients throughout your career. Here we offer an approach to choosing biologic treatments based on individual patient characteristics, including disease severity, comorbidities, and ultimate treatment goals.

Immune Pathogenesis

Although the pathogenesis of psoriasis is complex and outside the scope of this article, we do recommend clinicians keep in mind the current understanding of pathways involved and ways our therapies alter them. Briefly, psoriasis is a T cell–mediated disease in which IL-12 and IL-23 released by activated dendritic cells activate T helper cells including T_H1, T_H17, and T_H22. These cells produce additional cytokines, including IFN-γ, tumor necrosis factor (TNF) α, IL-17, and IL-22, which propagate the immune response and lead to keratinocyte hyperproliferation. In general, psoriasis medications work by altering T-cell activation, effector cytokines, or cytokine receptors.

Comorbidities

A targeted approach should take into consideration the immune dysregulation shared by psoriasis and associated comorbidities (Table 1). One goal of biologic treatments is to improve comorbidities when possible. At minimum, selected treatments should not exacerbate these conditions.

Treatment Goals

Establishing treatment goals can help shape patient expectations and provide a plan for clinicians. In 2017, the National Psoriasis Foundation published a treat-to-target approach using body surface area (BSA) measurements at baseline, 3 months, and then every 6 months after starting a new treatment.¹² The target response is a decrease in psoriasis to 1% or less BSA at 3 months and to maintain this response when evaluated at 6-month intervals. Alternatively, a target of 3% BSA after 3 months is satisfactory if the patient improves by 75% BSA overall. If these targets are not met after 6 months, therapeutic alternatives can be considered.¹²

Biologic Treatment of Psoriasis

Treatment options for patients with psoriasis depend first on disease severity. Topicals and phototherapy are first line for mild to moderate disease. For moderate to severe disease, addition of systemic agents such as methotrexate, cyclosporine, or acitretin; small-molecular-weight immunomodulators such as apremilast; or biologic medications should be considered. Current biologics available for moderate to severe plaque psoriasis target TNF-α, IL-12/IL-23, IL-23, IL-17A, or IL-17A receptor.

TNF-α Inhibitors

Tumor necrosis factor α inhibitors have been available for treatment of autoimmune disease for nearly 20 years. These medications block either soluble cytokine or membrane-bound cytokine. All are given as subcutaneous injections, except for infliximab, which is a weight-based infusion.

Efficacy
Tumor necrosis factor α inhibitors are the first class to demonstrate long-term efficacy and safety in both psoriasis and psoriatic arthritis (PsA). Etanercept was approved for adults with PsA in 2002 and psoriasis in 2004, and later for pediatric psoriasis (≥4 years of age) in 2016 (Table 2). Although etanercept has a sustained safety profile, the response rates are not as high as other anti–TNF-α inhibitors. Adalimumab is one of the most prescribed biologics, with a total of 10 indications at present, including PsA. Infliximab is an intravenous infusion that demonstrates a rapid and sustained response in most patients. The dose and dosing interval can be adjusted according to response. Certolizumab pegol was approved for PsA in 2013 and for psoriasis in 2018.

Safety
To evaluate long-term safety, a multicenter prospective registry study (Psoriasis Longitudinal Assessment and Registry [PSOLAR]) was initiated in 2007 to follow clinical outcomes. Data through 2013 showed no significant increase in rates of infection, malignancy, or major adverse cardiovascular events in more than 12,000 patients.¹³

Conflicting information exists in the literature regarding risk for malignancy with TNF-α inhibitors. One recent retrospective cohort study suggested a slightly increased risk for malignancies other than nonmelanoma skin cancers in patients on TNF-α inhibitors for more than 12 months (relative risk, 1.54).¹⁴ Reports of increased risk for cutaneous squamous cell carcinomas necessitate regular skin checks.¹⁵ A potential risk for lymphoma has been noted, though having psoriasis itself imparts an increased risk for Hodgkin and cutaneous T-cell lymphoma.¹⁶

Reactivation of tuberculosis and hepatitis have been reported with TNF-α inhibition. Data suggest that infliximab may be associated with more serious infections.¹³

Demyelinating conditions such as multiple sclerosis have occurred de novo or worsened in patients on TNF-α inhibitors.¹⁷ Tumor necrosis factor α blockers should be avoided in patients with decompensated heart failure. Rare cases of liver enzyme elevation and cytopenia have been noted. Additionally, lupuslike syndromes, which are generally reversible upon discontinuation, have occurred in some patients.

Patient Selection
Tumor necrosis factor α inhibitors are the treatment of choice for patients with comorbid PsA. This class halts progression of joint destruction over time.¹⁸Select TNF-α inhibitors are indicated for inflammatory bowel disease (IBD) and are a preferred treatment in this patient population. Specifically, adalimumab and infliximab are approved for both Crohn disease (CD) and ulcerative colitis. Certolizumab pegol is approved for CD.

Tumor necrosis factor α is upregulated in obesity, cardiovascular disease, and atherosclerotic plaques. Evidence suggests that TNF-α blockers may lower cardiovascular risk over time.¹⁹ For patients with obesity, infliximab is a good option, as it is the only TNF-α inhibitor with weight-based dosing.

In patients with frequent infections or history of hepatitis C, etanercept has been the biologic most commonly used when no alternatives exist, in part due to its shorter half-life.

IL-12/IL-23 Inhibitor

Ustekinumab is a monoclonal antibody that binds the p40 subunit shared by IL-12 and IL-23, blocking their ability to bind receptors. IL-12 and IL-23 play a role in activating naïve T cells to become T_H1 or T_H17 cells, respectively.

Efficacy and Safety
Clinical trials demonstrate long-term efficacy of ustekinumab, which was approved for psoriasis in 2009, PsA in 2013, and later pediatric psoriasis (≥12 years of age) in 2017. Dosing is listed in Table 2.

Laboratory abnormalities did not arise in trials. Periodic tuberculosis screening is required. Prospective data over 5 years showed very low rates of adverse events (AEs), serious infections, malignancies, and major adverse cardiovascular events.²⁰ Ustekinumab did not worsen or improve demyelinating disease and appears safe in this population.

Patient Selection
Ustekinumab is approved for PsA and is a good option for those who are not candidates for TNF-α and IL-17 inhibitors. Ustekinumab also is approved for CD. The dosing interval of 12 weeks makes ustekinumab convenient for patients. Two dosages exist based on the patient’s weight, offering an advantage to obese patients.

IL-17/IL-17R Inhibitors

Activated T_H17 cells produce the IL-17 cytokine family, which stimulates keratinocyte proliferation and dermal inflammation. Secukinumab is a fully human monoclonal antibody, and ixekizumab is a humanized monoclonal antibody; both target IL-17A. Brodalumab targets the IL-17A receptor.

Efficacy and Safety
IL-17 inhibitors showed impressive and rapid responses in trials.^21-23 The subsets of patients who responded well and continued treatment in extension trials demonstrated that these treatments maintain efficacy over time.^24-26

In addition to tuberculosis reactivation, there is a small increased risk for cutaneous candidiasis with IL-17 inhibitors, which can be managed without stopping treatment. Laboratory abnormalities were limited to mild neutropenia, which was not associated with increased risk for infection.^21-23 With ixekizumab, neutropenia was seen more commonly in the first 12 weeks.²²

IL-17 is highly expressed in the gut mucosa, and its inhibition is thought to weaken the barrier function of the gut mucosa, promoting inflammation. As a consequence, this class is contraindicated in patients with IBD due to exacerbations of existing IBD and cases of new-onset IBD.^21-23 Symptoms of diarrhea, abdominal pain, blood in stool, or nighttime stooling on review of gastrointestinal tract symptoms should prompt further evaluation.

Brodalumab has a unique warning for risk for suicidal ideation and behavior.²³ Depression is more common in the psoriasis population in general; therefore, physicians should be aware of this potential comorbidity regardless of the treatment plan. Because the response rates are so impressive with brodalumab, the Risk Evaluation and Mitigation Strategy (REMS) program was established to ensure understanding of this risk so that patients can be appropriately counseled and managed.

Patient Selection
The improvement in psoriasis is rapid and may occur as early as week 2 to 3 of treatment after initiation of IL-17 inhibitors. Ixekizumab and secukinumab also are approved for PsA. Although improvement in joint disease is not as fast as with the anti-TNF inhibitors, notable improvement occurs by week 20 to 24.²⁷

IL-23 Inhibitors

Guselkumab and tildrakizumab are the newest biologics for psoriasis, approved in 2017 and 2018, respectively. Both are monoclonal antibodies against the p19 subunit of IL-23, which blocks activation of T_H17 cells.

Efficacy and Safety
Guselkumab and tildrakizumab demonstrated efficacy with minimal AEs or precautions noted thus far.^28,29 Infections are again a risk, making tuberculosis testing the only recommended monitoring.

Patient Selection
Both medications offer another effective and safe option for patients with psoriasis. Similar to ustekinumab, the dosing interval of 12 weeks for tildrakizumab is ideal for patients who have needle phobia or are unable to administer their own injections.

Special Populations

Pregnancy

Antibodies cross the placenta as pregnancy progresses, with the highest rate in the third trimester. Certolizumab pegol has shown the lowest concentrations in infant serum, possibly due to its unique structure lacking the fragment crystallizable region required for passage through the placenta.³⁰ For this reason, certolizumab pegol is a treatment of choice if biologic therapy is warranted during pregnancy.

Much of the pregnancy data for the remaining TNF-α inhibitors come from patients with rheumatoid arthritis or CD. In these populations, rates of major birth defects and miscarriages do not differ greatly from untreated women with these conditions.³¹ One retrospective study of unintentional pregnancies in women receiving ustekinumab showed rates of AEs similar to the general population.³²

Pregnancy data for IL-17 or IL-23 inhibitors are largely limited to animal studies. One retrospective study of women exposed to secukinumab early in gestation showed no increased risk for pregnancy-related AEs.³³ Discontinuation is still recommended for patients who become pregnant.

Pediatric Patients

Etanercept is approved for pediatric psoriatic patients 4 years and older. Children with juvenile idiopathic arthritis who are 2 years and older can receive etanercept. Ustekinumab is safe and effective for pediatric psoriatic patients 12 years and older, offering a second biologic option in children.

Although not approved for pediatric psoriasis, adalimumab is approved in pediatric CD (≥6 years of age) and for juvenile idiopathic arthritis (≥2 years of age). Infliximab is approved for children 6 years and older with CD or ulcerative colitis.

Monitoring

Periodic tuberculosis screening is recommended for all biologics. For patients with latent tuberculosis, biologics may be restarted after 1 month of treatment of tuberculosis.

Prior to initiation of biologics, patients should be screened for hepatitis with hepatitis B surface antigen and antibody, hepatitis B core antibody, and hepatitis C antibody. Patients at risk for human immunodeficiency virus also should be screened.

Generally, complete blood cell count and comprehensive metabolic profile are advisable prior to starting a biologic. Opinions differ on frequency of repeating laboratory work. Complete blood cell count and comprehensive metabolic profile should be monitored at least every 3 to 6 months in patients on TNF-α inhibitors, and neutrophil count should be monitored during the induction phase of IL-17 inhibitors.

All patients with psoriasis should maintain age-appropriate cancer screenings, especially those on biologics. If malignancy is discovered, biologic medication should be discontinued. Debate exists as to when therapy can be safely restarted following treatment of malignancy. Patients who are considered at low risk for recurrence may opt to restart a biologic after 5 years, or sooner if symptoms warrant.³⁴ This decision should involve the patient’s cancer specialist.

Conclusion

Treatment choices are based on psoriasis type and severity, comorbidities, patient preferences, and drug accessibility. One approach is detailed in Table 3. As research advances the understanding of psoriasis, this field will continue to rapidly change. Knowledge of the immunopathogenesis of psoriasis and its relation to comorbidities can direct your decision-making for individual patients.

Psoriasis is a T cell–mediated inflammatory disease that manifests as erythematous scaling plaques of the skin. In recent decades, our understanding of psoriasis has transformed from a disease isolated to the skin to a systemic disease impacting the overall health of those affected.

With recent elucidation of the pathways driving psoriasis, development of targeted therapies has resulted in an influx of options to the market. Navigating the options can seem overwhelming even to the seasoned clinician. Becoming familiar with a sound treatment approach during residency will create a foundation for biologic use in psoriasis patients throughout your career. Here we offer an approach to choosing biologic treatments based on individual patient characteristics, including disease severity, comorbidities, and ultimate treatment goals.

Immune Pathogenesis

Although the pathogenesis of psoriasis is complex and outside the scope of this article, we do recommend clinicians keep in mind the current understanding of pathways involved and ways our therapies alter them. Briefly, psoriasis is a T cell–mediated disease in which IL-12 and IL-23 released by activated dendritic cells activate T helper cells including T_H1, T_H17, and T_H22. These cells produce additional cytokines, including IFN-γ, tumor necrosis factor (TNF) α, IL-17, and IL-22, which propagate the immune response and lead to keratinocyte hyperproliferation. In general, psoriasis medications work by altering T-cell activation, effector cytokines, or cytokine receptors.

Comorbidities

A targeted approach should take into consideration the immune dysregulation shared by psoriasis and associated comorbidities (Table 1). One goal of biologic treatments is to improve comorbidities when possible. At minimum, selected treatments should not exacerbate these conditions.

Treatment Goals

Establishing treatment goals can help shape patient expectations and provide a plan for clinicians. In 2017, the National Psoriasis Foundation published a treat-to-target approach using body surface area (BSA) measurements at baseline, 3 months, and then every 6 months after starting a new treatment.¹² The target response is a decrease in psoriasis to 1% or less BSA at 3 months and to maintain this response when evaluated at 6-month intervals. Alternatively, a target of 3% BSA after 3 months is satisfactory if the patient improves by 75% BSA overall. If these targets are not met after 6 months, therapeutic alternatives can be considered.¹²

Biologic Treatment of Psoriasis

Treatment options for patients with psoriasis depend first on disease severity. Topicals and phototherapy are first line for mild to moderate disease. For moderate to severe disease, addition of systemic agents such as methotrexate, cyclosporine, or acitretin; small-molecular-weight immunomodulators such as apremilast; or biologic medications should be considered. Current biologics available for moderate to severe plaque psoriasis target TNF-α, IL-12/IL-23, IL-23, IL-17A, or IL-17A receptor.

TNF-α Inhibitors

Tumor necrosis factor α inhibitors have been available for treatment of autoimmune disease for nearly 20 years. These medications block either soluble cytokine or membrane-bound cytokine. All are given as subcutaneous injections, except for infliximab, which is a weight-based infusion.

Efficacy
Tumor necrosis factor α inhibitors are the first class to demonstrate long-term efficacy and safety in both psoriasis and psoriatic arthritis (PsA). Etanercept was approved for adults with PsA in 2002 and psoriasis in 2004, and later for pediatric psoriasis (≥4 years of age) in 2016 (Table 2). Although etanercept has a sustained safety profile, the response rates are not as high as other anti–TNF-α inhibitors. Adalimumab is one of the most prescribed biologics, with a total of 10 indications at present, including PsA. Infliximab is an intravenous infusion that demonstrates a rapid and sustained response in most patients. The dose and dosing interval can be adjusted according to response. Certolizumab pegol was approved for PsA in 2013 and for psoriasis in 2018.

Safety
To evaluate long-term safety, a multicenter prospective registry study (Psoriasis Longitudinal Assessment and Registry [PSOLAR]) was initiated in 2007 to follow clinical outcomes. Data through 2013 showed no significant increase in rates of infection, malignancy, or major adverse cardiovascular events in more than 12,000 patients.¹³

Conflicting information exists in the literature regarding risk for malignancy with TNF-α inhibitors. One recent retrospective cohort study suggested a slightly increased risk for malignancies other than nonmelanoma skin cancers in patients on TNF-α inhibitors for more than 12 months (relative risk, 1.54).¹⁴ Reports of increased risk for cutaneous squamous cell carcinomas necessitate regular skin checks.¹⁵ A potential risk for lymphoma has been noted, though having psoriasis itself imparts an increased risk for Hodgkin and cutaneous T-cell lymphoma.¹⁶

Reactivation of tuberculosis and hepatitis have been reported with TNF-α inhibition. Data suggest that infliximab may be associated with more serious infections.¹³

Demyelinating conditions such as multiple sclerosis have occurred de novo or worsened in patients on TNF-α inhibitors.¹⁷ Tumor necrosis factor α blockers should be avoided in patients with decompensated heart failure. Rare cases of liver enzyme elevation and cytopenia have been noted. Additionally, lupuslike syndromes, which are generally reversible upon discontinuation, have occurred in some patients.

Patient Selection
Tumor necrosis factor α inhibitors are the treatment of choice for patients with comorbid PsA. This class halts progression of joint destruction over time.¹⁸Select TNF-α inhibitors are indicated for inflammatory bowel disease (IBD) and are a preferred treatment in this patient population. Specifically, adalimumab and infliximab are approved for both Crohn disease (CD) and ulcerative colitis. Certolizumab pegol is approved for CD.

Tumor necrosis factor α is upregulated in obesity, cardiovascular disease, and atherosclerotic plaques. Evidence suggests that TNF-α blockers may lower cardiovascular risk over time.¹⁹ For patients with obesity, infliximab is a good option, as it is the only TNF-α inhibitor with weight-based dosing.

In patients with frequent infections or history of hepatitis C, etanercept has been the biologic most commonly used when no alternatives exist, in part due to its shorter half-life.

IL-12/IL-23 Inhibitor

Ustekinumab is a monoclonal antibody that binds the p40 subunit shared by IL-12 and IL-23, blocking their ability to bind receptors. IL-12 and IL-23 play a role in activating naïve T cells to become T_H1 or T_H17 cells, respectively.

Efficacy and Safety
Clinical trials demonstrate long-term efficacy of ustekinumab, which was approved for psoriasis in 2009, PsA in 2013, and later pediatric psoriasis (≥12 years of age) in 2017. Dosing is listed in Table 2.

Laboratory abnormalities did not arise in trials. Periodic tuberculosis screening is required. Prospective data over 5 years showed very low rates of adverse events (AEs), serious infections, malignancies, and major adverse cardiovascular events.²⁰ Ustekinumab did not worsen or improve demyelinating disease and appears safe in this population.

Patient Selection
Ustekinumab is approved for PsA and is a good option for those who are not candidates for TNF-α and IL-17 inhibitors. Ustekinumab also is approved for CD. The dosing interval of 12 weeks makes ustekinumab convenient for patients. Two dosages exist based on the patient’s weight, offering an advantage to obese patients.

IL-17/IL-17R Inhibitors

Activated T_H17 cells produce the IL-17 cytokine family, which stimulates keratinocyte proliferation and dermal inflammation. Secukinumab is a fully human monoclonal antibody, and ixekizumab is a humanized monoclonal antibody; both target IL-17A. Brodalumab targets the IL-17A receptor.

Efficacy and Safety
IL-17 inhibitors showed impressive and rapid responses in trials.^21-23 The subsets of patients who responded well and continued treatment in extension trials demonstrated that these treatments maintain efficacy over time.^24-26

In addition to tuberculosis reactivation, there is a small increased risk for cutaneous candidiasis with IL-17 inhibitors, which can be managed without stopping treatment. Laboratory abnormalities were limited to mild neutropenia, which was not associated with increased risk for infection.^21-23 With ixekizumab, neutropenia was seen more commonly in the first 12 weeks.²²

IL-17 is highly expressed in the gut mucosa, and its inhibition is thought to weaken the barrier function of the gut mucosa, promoting inflammation. As a consequence, this class is contraindicated in patients with IBD due to exacerbations of existing IBD and cases of new-onset IBD.^21-23 Symptoms of diarrhea, abdominal pain, blood in stool, or nighttime stooling on review of gastrointestinal tract symptoms should prompt further evaluation.

Brodalumab has a unique warning for risk for suicidal ideation and behavior.²³ Depression is more common in the psoriasis population in general; therefore, physicians should be aware of this potential comorbidity regardless of the treatment plan. Because the response rates are so impressive with brodalumab, the Risk Evaluation and Mitigation Strategy (REMS) program was established to ensure understanding of this risk so that patients can be appropriately counseled and managed.

Patient Selection
The improvement in psoriasis is rapid and may occur as early as week 2 to 3 of treatment after initiation of IL-17 inhibitors. Ixekizumab and secukinumab also are approved for PsA. Although improvement in joint disease is not as fast as with the anti-TNF inhibitors, notable improvement occurs by week 20 to 24.²⁷

IL-23 Inhibitors

Guselkumab and tildrakizumab are the newest biologics for psoriasis, approved in 2017 and 2018, respectively. Both are monoclonal antibodies against the p19 subunit of IL-23, which blocks activation of T_H17 cells.

Efficacy and Safety
Guselkumab and tildrakizumab demonstrated efficacy with minimal AEs or precautions noted thus far.^28,29 Infections are again a risk, making tuberculosis testing the only recommended monitoring.

Patient Selection
Both medications offer another effective and safe option for patients with psoriasis. Similar to ustekinumab, the dosing interval of 12 weeks for tildrakizumab is ideal for patients who have needle phobia or are unable to administer their own injections.

Special Populations

Pregnancy

Antibodies cross the placenta as pregnancy progresses, with the highest rate in the third trimester. Certolizumab pegol has shown the lowest concentrations in infant serum, possibly due to its unique structure lacking the fragment crystallizable region required for passage through the placenta.³⁰ For this reason, certolizumab pegol is a treatment of choice if biologic therapy is warranted during pregnancy.

Much of the pregnancy data for the remaining TNF-α inhibitors come from patients with rheumatoid arthritis or CD. In these populations, rates of major birth defects and miscarriages do not differ greatly from untreated women with these conditions.³¹ One retrospective study of unintentional pregnancies in women receiving ustekinumab showed rates of AEs similar to the general population.³²

Pregnancy data for IL-17 or IL-23 inhibitors are largely limited to animal studies. One retrospective study of women exposed to secukinumab early in gestation showed no increased risk for pregnancy-related AEs.³³ Discontinuation is still recommended for patients who become pregnant.

Pediatric Patients

Etanercept is approved for pediatric psoriatic patients 4 years and older. Children with juvenile idiopathic arthritis who are 2 years and older can receive etanercept. Ustekinumab is safe and effective for pediatric psoriatic patients 12 years and older, offering a second biologic option in children.

Although not approved for pediatric psoriasis, adalimumab is approved in pediatric CD (≥6 years of age) and for juvenile idiopathic arthritis (≥2 years of age). Infliximab is approved for children 6 years and older with CD or ulcerative colitis.

Monitoring

Periodic tuberculosis screening is recommended for all biologics. For patients with latent tuberculosis, biologics may be restarted after 1 month of treatment of tuberculosis.

Prior to initiation of biologics, patients should be screened for hepatitis with hepatitis B surface antigen and antibody, hepatitis B core antibody, and hepatitis C antibody. Patients at risk for human immunodeficiency virus also should be screened.

Generally, complete blood cell count and comprehensive metabolic profile are advisable prior to starting a biologic. Opinions differ on frequency of repeating laboratory work. Complete blood cell count and comprehensive metabolic profile should be monitored at least every 3 to 6 months in patients on TNF-α inhibitors, and neutrophil count should be monitored during the induction phase of IL-17 inhibitors.

All patients with psoriasis should maintain age-appropriate cancer screenings, especially those on biologics. If malignancy is discovered, biologic medication should be discontinued. Debate exists as to when therapy can be safely restarted following treatment of malignancy. Patients who are considered at low risk for recurrence may opt to restart a biologic after 5 years, or sooner if symptoms warrant.³⁴ This decision should involve the patient’s cancer specialist.

Conclusion

Treatment choices are based on psoriasis type and severity, comorbidities, patient preferences, and drug accessibility. One approach is detailed in Table 3. As research advances the understanding of psoriasis, this field will continue to rapidly change. Knowledge of the immunopathogenesis of psoriasis and its relation to comorbidities can direct your decision-making for individual patients.

Psoriasis is a T cell–mediated inflammatory disease that manifests as erythematous scaling plaques of the skin. In recent decades, our understanding of psoriasis has transformed from a disease isolated to the skin to a systemic disease impacting the overall health of those affected.

With recent elucidation of the pathways driving psoriasis, development of targeted therapies has resulted in an influx of options to the market. Navigating the options can seem overwhelming even to the seasoned clinician. Becoming familiar with a sound treatment approach during residency will create a foundation for biologic use in psoriasis patients throughout your career. Here we offer an approach to choosing biologic treatments based on individual patient characteristics, including disease severity, comorbidities, and ultimate treatment goals.

Immune Pathogenesis

Although the pathogenesis of psoriasis is complex and outside the scope of this article, we do recommend clinicians keep in mind the current understanding of pathways involved and ways our therapies alter them. Briefly, psoriasis is a T cell–mediated disease in which IL-12 and IL-23 released by activated dendritic cells activate T helper cells including T_H1, T_H17, and T_H22. These cells produce additional cytokines, including IFN-γ, tumor necrosis factor (TNF) α, IL-17, and IL-22, which propagate the immune response and lead to keratinocyte hyperproliferation. In general, psoriasis medications work by altering T-cell activation, effector cytokines, or cytokine receptors.

Comorbidities

A targeted approach should take into consideration the immune dysregulation shared by psoriasis and associated comorbidities (Table 1). One goal of biologic treatments is to improve comorbidities when possible. At minimum, selected treatments should not exacerbate these conditions.

Treatment Goals

Establishing treatment goals can help shape patient expectations and provide a plan for clinicians. In 2017, the National Psoriasis Foundation published a treat-to-target approach using body surface area (BSA) measurements at baseline, 3 months, and then every 6 months after starting a new treatment.¹² The target response is a decrease in psoriasis to 1% or less BSA at 3 months and to maintain this response when evaluated at 6-month intervals. Alternatively, a target of 3% BSA after 3 months is satisfactory if the patient improves by 75% BSA overall. If these targets are not met after 6 months, therapeutic alternatives can be considered.¹²

Biologic Treatment of Psoriasis

Treatment options for patients with psoriasis depend first on disease severity. Topicals and phototherapy are first line for mild to moderate disease. For moderate to severe disease, addition of systemic agents such as methotrexate, cyclosporine, or acitretin; small-molecular-weight immunomodulators such as apremilast; or biologic medications should be considered. Current biologics available for moderate to severe plaque psoriasis target TNF-α, IL-12/IL-23, IL-23, IL-17A, or IL-17A receptor.

TNF-α Inhibitors

Tumor necrosis factor α inhibitors have been available for treatment of autoimmune disease for nearly 20 years. These medications block either soluble cytokine or membrane-bound cytokine. All are given as subcutaneous injections, except for infliximab, which is a weight-based infusion.

Efficacy
Tumor necrosis factor α inhibitors are the first class to demonstrate long-term efficacy and safety in both psoriasis and psoriatic arthritis (PsA). Etanercept was approved for adults with PsA in 2002 and psoriasis in 2004, and later for pediatric psoriasis (≥4 years of age) in 2016 (Table 2). Although etanercept has a sustained safety profile, the response rates are not as high as other anti–TNF-α inhibitors. Adalimumab is one of the most prescribed biologics, with a total of 10 indications at present, including PsA. Infliximab is an intravenous infusion that demonstrates a rapid and sustained response in most patients. The dose and dosing interval can be adjusted according to response. Certolizumab pegol was approved for PsA in 2013 and for psoriasis in 2018.

Safety
To evaluate long-term safety, a multicenter prospective registry study (Psoriasis Longitudinal Assessment and Registry [PSOLAR]) was initiated in 2007 to follow clinical outcomes. Data through 2013 showed no significant increase in rates of infection, malignancy, or major adverse cardiovascular events in more than 12,000 patients.¹³

Conflicting information exists in the literature regarding risk for malignancy with TNF-α inhibitors. One recent retrospective cohort study suggested a slightly increased risk for malignancies other than nonmelanoma skin cancers in patients on TNF-α inhibitors for more than 12 months (relative risk, 1.54).¹⁴ Reports of increased risk for cutaneous squamous cell carcinomas necessitate regular skin checks.¹⁵ A potential risk for lymphoma has been noted, though having psoriasis itself imparts an increased risk for Hodgkin and cutaneous T-cell lymphoma.¹⁶

Reactivation of tuberculosis and hepatitis have been reported with TNF-α inhibition. Data suggest that infliximab may be associated with more serious infections.¹³

Demyelinating conditions such as multiple sclerosis have occurred de novo or worsened in patients on TNF-α inhibitors.¹⁷ Tumor necrosis factor α blockers should be avoided in patients with decompensated heart failure. Rare cases of liver enzyme elevation and cytopenia have been noted. Additionally, lupuslike syndromes, which are generally reversible upon discontinuation, have occurred in some patients.

Patient Selection
Tumor necrosis factor α inhibitors are the treatment of choice for patients with comorbid PsA. This class halts progression of joint destruction over time.¹⁸Select TNF-α inhibitors are indicated for inflammatory bowel disease (IBD) and are a preferred treatment in this patient population. Specifically, adalimumab and infliximab are approved for both Crohn disease (CD) and ulcerative colitis. Certolizumab pegol is approved for CD.

Tumor necrosis factor α is upregulated in obesity, cardiovascular disease, and atherosclerotic plaques. Evidence suggests that TNF-α blockers may lower cardiovascular risk over time.¹⁹ For patients with obesity, infliximab is a good option, as it is the only TNF-α inhibitor with weight-based dosing.

In patients with frequent infections or history of hepatitis C, etanercept has been the biologic most commonly used when no alternatives exist, in part due to its shorter half-life.

IL-12/IL-23 Inhibitor

Ustekinumab is a monoclonal antibody that binds the p40 subunit shared by IL-12 and IL-23, blocking their ability to bind receptors. IL-12 and IL-23 play a role in activating naïve T cells to become T_H1 or T_H17 cells, respectively.

Efficacy and Safety
Clinical trials demonstrate long-term efficacy of ustekinumab, which was approved for psoriasis in 2009, PsA in 2013, and later pediatric psoriasis (≥12 years of age) in 2017. Dosing is listed in Table 2.

Laboratory abnormalities did not arise in trials. Periodic tuberculosis screening is required. Prospective data over 5 years showed very low rates of adverse events (AEs), serious infections, malignancies, and major adverse cardiovascular events.²⁰ Ustekinumab did not worsen or improve demyelinating disease and appears safe in this population.

Patient Selection
Ustekinumab is approved for PsA and is a good option for those who are not candidates for TNF-α and IL-17 inhibitors. Ustekinumab also is approved for CD. The dosing interval of 12 weeks makes ustekinumab convenient for patients. Two dosages exist based on the patient’s weight, offering an advantage to obese patients.

IL-17/IL-17R Inhibitors

Activated T_H17 cells produce the IL-17 cytokine family, which stimulates keratinocyte proliferation and dermal inflammation. Secukinumab is a fully human monoclonal antibody, and ixekizumab is a humanized monoclonal antibody; both target IL-17A. Brodalumab targets the IL-17A receptor.

Efficacy and Safety
IL-17 inhibitors showed impressive and rapid responses in trials.^21-23 The subsets of patients who responded well and continued treatment in extension trials demonstrated that these treatments maintain efficacy over time.^24-26

In addition to tuberculosis reactivation, there is a small increased risk for cutaneous candidiasis with IL-17 inhibitors, which can be managed without stopping treatment. Laboratory abnormalities were limited to mild neutropenia, which was not associated with increased risk for infection.^21-23 With ixekizumab, neutropenia was seen more commonly in the first 12 weeks.²²

IL-17 is highly expressed in the gut mucosa, and its inhibition is thought to weaken the barrier function of the gut mucosa, promoting inflammation. As a consequence, this class is contraindicated in patients with IBD due to exacerbations of existing IBD and cases of new-onset IBD.^21-23 Symptoms of diarrhea, abdominal pain, blood in stool, or nighttime stooling on review of gastrointestinal tract symptoms should prompt further evaluation.

Brodalumab has a unique warning for risk for suicidal ideation and behavior.²³ Depression is more common in the psoriasis population in general; therefore, physicians should be aware of this potential comorbidity regardless of the treatment plan. Because the response rates are so impressive with brodalumab, the Risk Evaluation and Mitigation Strategy (REMS) program was established to ensure understanding of this risk so that patients can be appropriately counseled and managed.

Patient Selection
The improvement in psoriasis is rapid and may occur as early as week 2 to 3 of treatment after initiation of IL-17 inhibitors. Ixekizumab and secukinumab also are approved for PsA. Although improvement in joint disease is not as fast as with the anti-TNF inhibitors, notable improvement occurs by week 20 to 24.²⁷

IL-23 Inhibitors

Guselkumab and tildrakizumab are the newest biologics for psoriasis, approved in 2017 and 2018, respectively. Both are monoclonal antibodies against the p19 subunit of IL-23, which blocks activation of T_H17 cells.

Efficacy and Safety
Guselkumab and tildrakizumab demonstrated efficacy with minimal AEs or precautions noted thus far.^28,29 Infections are again a risk, making tuberculosis testing the only recommended monitoring.

Patient Selection
Both medications offer another effective and safe option for patients with psoriasis. Similar to ustekinumab, the dosing interval of 12 weeks for tildrakizumab is ideal for patients who have needle phobia or are unable to administer their own injections.

Special Populations

Pregnancy

Antibodies cross the placenta as pregnancy progresses, with the highest rate in the third trimester. Certolizumab pegol has shown the lowest concentrations in infant serum, possibly due to its unique structure lacking the fragment crystallizable region required for passage through the placenta.³⁰ For this reason, certolizumab pegol is a treatment of choice if biologic therapy is warranted during pregnancy.

Much of the pregnancy data for the remaining TNF-α inhibitors come from patients with rheumatoid arthritis or CD. In these populations, rates of major birth defects and miscarriages do not differ greatly from untreated women with these conditions.³¹ One retrospective study of unintentional pregnancies in women receiving ustekinumab showed rates of AEs similar to the general population.³²

Pregnancy data for IL-17 or IL-23 inhibitors are largely limited to animal studies. One retrospective study of women exposed to secukinumab early in gestation showed no increased risk for pregnancy-related AEs.³³ Discontinuation is still recommended for patients who become pregnant.

Pediatric Patients

Etanercept is approved for pediatric psoriatic patients 4 years and older. Children with juvenile idiopathic arthritis who are 2 years and older can receive etanercept. Ustekinumab is safe and effective for pediatric psoriatic patients 12 years and older, offering a second biologic option in children.

Although not approved for pediatric psoriasis, adalimumab is approved in pediatric CD (≥6 years of age) and for juvenile idiopathic arthritis (≥2 years of age). Infliximab is approved for children 6 years and older with CD or ulcerative colitis.

Monitoring

Periodic tuberculosis screening is recommended for all biologics. For patients with latent tuberculosis, biologics may be restarted after 1 month of treatment of tuberculosis.

Prior to initiation of biologics, patients should be screened for hepatitis with hepatitis B surface antigen and antibody, hepatitis B core antibody, and hepatitis C antibody. Patients at risk for human immunodeficiency virus also should be screened.

Generally, complete blood cell count and comprehensive metabolic profile are advisable prior to starting a biologic. Opinions differ on frequency of repeating laboratory work. Complete blood cell count and comprehensive metabolic profile should be monitored at least every 3 to 6 months in patients on TNF-α inhibitors, and neutrophil count should be monitored during the induction phase of IL-17 inhibitors.

All patients with psoriasis should maintain age-appropriate cancer screenings, especially those on biologics. If malignancy is discovered, biologic medication should be discontinued. Debate exists as to when therapy can be safely restarted following treatment of malignancy. Patients who are considered at low risk for recurrence may opt to restart a biologic after 5 years, or sooner if symptoms warrant.³⁴ This decision should involve the patient’s cancer specialist.

Conclusion

Treatment choices are based on psoriasis type and severity, comorbidities, patient preferences, and drug accessibility. One approach is detailed in Table 3. As research advances the understanding of psoriasis, this field will continue to rapidly change. Knowledge of the immunopathogenesis of psoriasis and its relation to comorbidities can direct your decision-making for individual patients.

Increased understanding of the pathophysiology of psoriasis has been one of the driving forces in the development of new therapies. An understanding of the processes involved is important in the optimal management of the disease. The last 30 years of research and clinical practice have revolutionized our understanding of the pathogenesis of psoriasis as the dysregulation of immunity triggered by environmental and genetic stimuli. Psoriasis was originally regarded as a primary disorder of epidermal hyperproliferation. However, experimental models and clinical results from immunomodulating therapies have refined this perspective in conceptualizing psoriasis as a genetically programmed pathologic interaction among resident skin cells; infiltrating immunocytes; and a host of proinflammatory cytokines, chemokines, and growth factors produced by these immunocytes. Two populations of immunocytes and their respective signaling molecules collaborate in the pathogenesis: (1) innate immunocytes, mediated by antigen-presenting cells (APCs)(including natural killer [NK] T lymphocytes, Langerhans cells, and neutrophils), and (2) acquired or adaptive immunocytes, mediated by mature CD4⁺ and CD8⁺ T lymphocytes in the skin. Such dysregulation of immunity and subsequent inflammation is responsible for the development and perpetuation of the clinical plaques and histological inflammatory infiltrate characteristic of psoriasis.

Although psoriasis is considered to be an immune-mediated disease in which intralesional T lymphocytes and their proinflammatory signals trigger primed basal layer keratinocytes to rapidly proliferate, debate and research focus on the stimulus that incites this inflammatory process. Our current understanding considers psoriasis to be triggered by exogenous or endogenous environmental stimuli in genetically susceptible individuals. Such stimuli include group A streptococcal pharyngitis, viremia, allergic drug reactions, antimalarial drugs, lithium, beta-blockers, IFN-α, withdrawal of systemic corticosteroids, local trauma (Köbner phenomenon), and emotional stress. These stimuli correlate with the onset or flares of psoriatic lesions. Psoriasis genetics centers on susceptibility loci and corresponding candidate genes, particularly the psoriasis susceptibility (PSORS) 1 locus on the major histocompatibility complex (MHC) class I region. Current research on the pathogenesis of psoriasis examines the complex interactions among immunologic mechanisms, environmental stimuli, and genetic susceptibility. After discussing the clinical presentation and histopathologic features of psoriasis, we will review the pathophysiology of psoriasis through noteworthy developments, including serendipitous observations, reactions to therapies, clinical trials, and animal model systems that have shaped our view of the disease process. In addition to the classic skin lesions, approximately 23% of psoriasis patients develop psoriatic arthritis, with a 10-year latency after diagnosis of psoriasis.¹

Principles of Immunity

The immune system, intended to protect its host from foreign invaders and unregulated cell growth, employs 2 main effector pathways—the innate and the acquired (or adaptive) immune responses—both of which contribute to the pathophysiology of psoriasis.² Innate immunity responses occur within minutes to hours of antigen exposure but fail to develop memory for when the antigen is encountered again. However, adaptive immunity responses take days to weeks to respond after challenged with an antigen. The adaptive immune cells have the capacity to respond to a greater range of antigens and develop immunologic memory via rearrangement of antigen receptors on B and T cells. These specialized B and T cells can then be promptly mobilized and differentiated into mature effector cells that protect the host from a foreign pathogen.

Innate and adaptive immune responses are highly intertwined; they can initiate, perpetuate, and terminate the immune mechanisms responsible for inflammation. They can modify the nature of the immune response by altering the relative proportions of type 1 (T_H1), type 2 (T_H2), and the more recently discovered type 17 (T_H17) subset of helper T cells and their respective signaling molecules. A T_H1 response is essential for a cellular immunologic reaction to intracellular bacteria and viruses or cellular immunity. A T_H2 response promotes IgE synthesis, eosinophilia, and mast cell maturation for extracellular parasites and helminthes as well as humoral immunity, while a T_H17 response is important for cell-mediated immunity to extracellular bacteria and plays a role in autoimmunity.³ The innate and adaptive immune responses employ common effector molecules such as chemokines and cytokines, which are essential in mediating an immune response.

Implicating Dysregulation of Immunity

Our present appreciation of the pathogenesis of psoriasis is based on the history of trial-and-error therapies; serendipitous discoveries; and the current immune targeting drugs used in a variety of chronic inflammatory conditions, including rheumatoid arthritis, ankylosing spondylitis, and inflammatory bowel disease. Before the mid-1980s, research focused on the hyperproliferative epidermal cells as the primary pathology because a markedly thickened epidermis was indeed demonstrated on histologic specimens. Altered cell-cycle kinetics were thought to be the culprit behind the hyperkeratotic plaques. Thus, initial treatments centered on oncologic and antimitotic therapies used to arrest keratinocyte proliferation with agents such as arsenic, ammoniated mercury, and methotrexate.⁴

However, a paradigm shift from targeting epidermal keratinocytes to immunocyte populations was recognized when a patient receiving cyclosporine to prevent transplant rejection noted clearing of psoriatic lesions in the 1980s.⁵ Cyclosporine was observed to inhibit messenger RNA transcription of T-cell cytokines, thereby implicating immunologic dysregulation, specifically T-cell hyperactivity, in the pathogenesis of psoriasis.⁶ However, the concentrations of oral cyclosporine reached in the epidermis exerted direct effects on keratinocyte proliferation and lymphocyte function in these patients.⁷ Thus, the question was raised as to whether the keratinocytes or the lymphocytes drove the psoriatic plaques. The use of an IL-2 diphtheria toxin-fusion protein, denileukin diftitox, specific for activated T cells with high-affinity IL-2 receptors and nonreactive with keratinocytes, distinguished which cell type was responsible. This targeted T-cell toxin provided clinical and histological clearing of psoriatic plaques. Thus, T lymphocytes rather than keratinocytes were recognized as the definitive driver behind the psoriatic plaques.⁸

Additional studies have demonstrated that treatments that induce prolonged clearing of psoriatic lesions without continuous therapy, such as psoralen plus UVA irradiation, decreased the numbers of T cells in plaques by at least 90%.⁹ However, treatments that require continual therapy for satisfactory clinical results, such as cyclosporine and etretinate, simply suppress T-cell activity and proliferation.^10,11 Further evidence has linked cellular immunity with the pathogenesis of psoriasis, defining it as a T_H1-type disease. Natural killer T cells were shown to be involved through the use of a severe combined immunodeficient mouse model. They were injected into prepsoriatic skin grafted on immunodeficient mice, creating a psoriatic plaque with an immune response showing cytokines from T_H1 cells rather than T_H2 cells.¹² When psoriatic plaques were treated topically with the toll-like receptor 7 agonist imiquimod, aggravation and spreading of the plaques were noted. The exacerbation of psoriasis was accompanied by an induction of lesional T_H1-type interferon produced by plasmacytoid dendritic cell (DC) precursors. Plasmacytoid DCs were observed to compose up to 16% of the total dermal infiltrate in psoriatic skin lesions based on their coexpression of BDCA2 and CD123.¹³ Additionally, cancer patients being treated with interferon alfa experienced induction of psoriasis.¹⁴ Moreover, patients being treated for warts with intralesional interferon alfa developed psoriatic plaques in neighboring prior asymptomatic skin.¹⁵ Patients with psoriasis who were treated with interferon gamma, a T_H1 cytokine type, also developed new plaques correlating with the sites of injection.¹⁶

Intralesional T Lymphocytes

Psoriatic lesions contain a host of innate immunocytes, such as APCs, NK cells, and neutrophils, as well as adaptive T cells and an inflammatory infiltrate. These cells include CD4 and CD8 subtypes in which the CD8⁺ cells predominate in the epidermis, while CD4⁺ cells show preference for the dermis.¹⁷ There are 2 groups of CD8⁺ cells: one group migrates to the epidermis, expressing the integrin CD103, while the other group is found in the dermis but may be headed to or from the epidermis. The CD8⁺ cells residing in the epidermis that express the integrin CD103 are capable of interacting with E-cadherin, which enables these cells to travel to the epidermis and bind resident cells. Immunophenotyping reveals that these mature T cells represent chiefly activated memory cells, including CD2⁺, CD3⁺, CD5⁺, CLA, CD28, and CD45RO⁺.¹⁸ Many of these cells express activation markers such as HLA-DR, CD25, and CD27, in addition to the T-cell receptor (TCR).

T-Lymphocyte Stimulation

Both mature CD4⁺ and CD8⁺ T cells can respond to the peptides presented by APCs. Although the specific antigen that these T cells are reacting to has not yet been elucidated, several antigenic stimuli have been proposed, including self-proteins, microbial pathogens, and microbial superantigens. The premise that self-reactive T lymphocytes may contribute to the disease process is derived from the molecular mimicry theory in which an exuberant immune response to a pathogen produces cross-reactivity with self-antigens.¹⁹ Considering that infections have been associated with the onset of psoriasis, this theory merits consideration. However, it also has been observed that T cells can be activated without antigens or superantigens but rather with direct contact with accessory cells.²⁰ No single theory has clearly emerged. Researchers continue to search for the inciting stimulus that triggers the T lymphocyte and attempt to determine whether T cells are reacting to a self-derived or non–self-derived antigen.

T-Lymphocyte Signaling

T-cell signaling is a highly coordinated process in which T lymphocytes recognize antigens via presentation by mature APCs in the skin rather than the lymphoid tissues. Such APCs expose antigenic peptides via class I or II MHC molecules for which receptors are present on the T-cell surface. The antigen recognition complex at the T-cell and APC interface, in concert with a host of antigen-independent co-stimulatory signals, regulates T-cell signaling and is referred to as the immunologic synapse. The antigen presentation and network of co-stimulatory and adhesion molecules optimize T-cell activation, and dermal DCs release IL-12 and IL-23 to promote a T_H1 and T_H17 response, respectively. The growth factors released by these helper T cells sustain neoangiogenesis, stimulate epidermal hyperproliferation, alter epidermal differentiation, and decrease susceptibility to apoptosis that characterizes the erythematous hypertrophic scaling lesions of psoriasis.²¹ Furthermore, the cytokines produced from the immunologic response, such as tumor necrosis factor (TNF) α, IFN-γ, and IL-2, correspond to cytokines that are upregulated in psoriatic plaques.²²

Integral components of the immunologic synapse complex include co-stimulatory signals such as CD28, CD40, CD80, and CD86, as well as adhesion molecules such as cytotoxic T-lymphocyte antigen 4 and lymphocyte function-associated antigen (LFA) 1, which possess corresponding receptors on the T cell. These molecules play a key role in T-cell signaling, as their disruption has been shown to decrease T-cell responsiveness and associated inflammation. The B7 family of molecules routinely interacts with CD28 T cells to co-stimulate T-cell activation. Cytotoxic T-lymphocyte antigen 4 immunoglobulin, an antibody on the T-cell surface, targets B7 and interferes with signaling between B7 and CD28. In psoriatic patients, this blockade was demonstrated to attenuate the T-cell response and correlated with a clinical and histological decrease in psoriasiform hyperplasia.²³ Biologic therapies that disrupt the LFA-1 component of the immunologic synapse also have demonstrated efficacy in the treatment of psoriasis. Alefacept is a human LFA-3 fusion protein that binds CD2 on T cells and blocks the interaction between LFA-3 on APCs and CD2 on memory CD45RO⁺ T cells and induces apoptosis of such T cells. Efalizumab is a human monoclonal antibody to the CD11 chain of LFA-1 that blocks the interaction between LFA-1 on the T cell and intercellular adhesion molecule 1 on an APC or endothelial cell. Both alefacept and efalizumab, 2 formerly marketed biologic therapies, demonstrated remarkable clinical reduction of psoriatic lesions, and alefacept has been shown to produce disease remission for up to 18 months after discontinuation of therapy.^24-26

NK T Cells

Natural killer T cells represent a subset of CD3⁺ T cells present in psoriatic plaques. Although NK T cells possess a TCR, they differ from T cells by displaying NK receptors comprised of lectin and immunoglobulin families. These cells exhibit remarkable specificity and are activated upon recognition of glycolipids presented by CD1d molecules. This process occurs in contrast to CD4⁺ and CD8⁺ T cells, which, due to their TCR diversity, respond to peptides processed by APCs and displayed on MHC molecules. Natural killer T cells can be classified into 2 subsets: (1) one group that expresses CD4 and preferentially produces T_H1- versus T_H2-type cytokines, and (2) another group that lacks CD4 and CD8 that only produces T_H1-type cytokines. The innate immune system employs NK T cells early in the immune response because of their direct cytotoxicity and rapid production of cytokines such as IFN-γ, which promotes a T_H1 inflammatory response, and IL-4, which promotes the development of T_H2 cells. Excessive or dysfunctional NK T cells have been associated with autoimmune diseases such as multiple sclerosis and inflammatory bowel disease as well as allergic contact dermatitis.^27-29

In psoriasis, NK T cells are located in the epidermis, closely situated to epidermal keratinocytes, which suggests a role for direct antigen presentation. Furthermore, CD1d is overexpressed throughout the epidermis of psoriatic plaques, whereas normally CD1d expression is confined to terminally differentiated keratinocytes. An in vitro study examining cytokine-based inflammation demonstrative of psoriasis treated cultured CD1d-positive keratinocytes with interferon gamma in the presence of alpha-galactosylceramide of the lectin family.³⁰ Interferon gamma was observed to enhance keratinocyte CD1d expression, and subsequently, CD1d-positive keratinocytes were found to activate NK T cells to produce high levels of IFN-γ, while levels of IL-4 remained undetectable. The preferential production of IFN-γ supports a T_H1-mediated mechanism regulated by NK T cells in the immunopathogenesis of psoriasis.

Dendritic Cells

Dendritic cells are APCs that process antigens in the tissues in which they reside, after which they migrate to local lymph nodes where they present their native antigens to T cells. This process allows the T-cell response to be tailored to the appropriate antigens in the corresponding tissues. Immature DCs that capture antigens mature by migrating to the T-cell center of the lymph node where they present their antigens to either MHC molecules or the CD1 family. This presentation results in T-cell proliferation and differentiation that correlates with the required type of T-cell response. Multiple subsets of APCs, including myeloid and plasmacytoid DCs, are highly represented in the epidermis and dermis of psoriatic plaques as compared with normal skin.³¹ Dermal DCs are thought to be responsible for activating both the T_H1 and T_H17 infiltrate by secreting IL-12 and IL-23, respectively. This mixed cellular response secretes cytokines and leads to a cascade of events involving keratinocytes, fibroblasts, endothelial cells, and neutrophils that create the cutaneous lesions seen in psoriasis.³

Although DCs play a pivotal role in eliciting an immune response against a foreign invader, they also contribute to the establishment of tolerance. Throughout their maturation, DCs are continuously sensing their environment, which shapes their production of T_H1- versus T_H2-type cytokines and subsequently the nature of the T-cell response. When challenged with a virus, bacteria, or unchecked cell growth, DCs mature into APCs. However, in the absence of a strong stimulus, DCs fail to mature into APCs and present self-peptides with MHC molecules, thereby creating regulatory T cells involved in peripheral tolerance.³² If this balance between immunogenic APCs and housekeeping T cells is upset, inflammatory conditions such as psoriasis can result.

Cytokines

Cytokines are low-molecular-weight glycoproteins that function as signals to produce inflammation, defense, tissue repair and remodeling, fibrosis, angiogenesis, and restriction of neoplastic growth.³³ Cytokines are produced by immunocytes such as lymphocytes and macrophages as well as nonimmunocytes such as endothelial cells and keratinocytes. Proinflammatory cytokines include IL-1, IL-2, the IL-17 family, IFN-γ, and TNF-α, while anti-inflammatory cytokines include IL-4 and IL-10. A relative preponderance of T_H1 proinflammatory cytokines or an insufficiency of T_H2 anti-inflammatory cytokines induces local inflammation and recruitment of additional immunocyte populations, which produce added cytokines.³⁴ A vicious cycle of inflammation occurs that results in cutaneous manifestations such as a plaque. Psoriatic lesions are characterized by a relative increase of T_H1-type (eg, IL-2, IFN-γ, TNF-α, TNF-β) to T_H2-type (eg, IL-4, IL-5, IL-6, IL-9, IL-10, IL-13) cytokines and an increase in T_H17-type cytokines. Natural killer T cells stimulated by CD1d-overexpressing keratinocytes increase production of proinflammatory IFN-γ without effect on the anti-inflammatory IL-4. In addition to the cytokines produced by T cells, APCs produce IL-18, IL-23, and TNF-α found in the inflammatory infiltrate of psoriatic plaques. Both IL-18 and IL-23 stimulate T_H1 cells to produce IFN-γ, and IL-23 stimulates T_H17 cells. Clearly, a T_H1- and T_H17-type pattern governs the immune effector cells and their respective cytokines present in psoriatic skin.

Tumor Necrosis Factor α

Although a network of cytokines is responsible for the inflammation of psoriasis, TNF-α has been implicated as a master proinflammatory cytokine of the innate immune response due to its widespread targets and sources. Tumor necrosis factor α is produced by activated T cells, keratinocytes, NK cells, macrophages, monocytes, Langerhans APCs, and endothelial cells. Psoriatic lesions demonstrate high concentrations of TNF-α, while the synovial fluid of psoriatic arthritis patients demonstrates elevated concentrations of TNF-α, IL-1, IL-6, and IL-8.³⁴ In psoriasis, TNF-α supports the expression of adhesion molecules (intercellular adhesion molecule 1 and P- and E-selectin), angiogenesis via vascular endothelial growth factor, the synthesis of proinflammatory molecules (IL-1, IL-6, IL-8, and nuclear factor κβ), and keratinocyte hyperproliferation via vasoactive intestinal peptide.³⁵

A role for TNF-α in psoriasis treatment was serendipitously discovered in a trial for Crohn disease in which infliximab, a mouse-human IgG1 anti–TNF-α monoclonal antibody, was observed to clear psoriatic plaques in a patient with both Crohn disease and psoriasis.³⁶ Immunotherapies that target TNF-α, including infliximab, etanercept, and adalimumab, demonstrate notable efficacy in the treatment of psoriasis.^37-39 Tumor necrosis factor α is regarded as the driver of the inflammatory cycle of psoriasis due to its numerous modes of production, capability to amplify other proinflammatory signals, and the efficacy and rapidity with which it produces clinical improvements in psoriasis.

IL-23/T_H17 Axis

A new distinct population of helper T cells has been shown to play an important role in psoriasis. These cells develop with the help of IL-23 (secreted by dermal DCs) and subsequently secrete cytokines such as IL-17; they are, therefore, named T_H17 cells. CD161 is considered a surface marker for these cells.⁴⁰ Strong evidence for this IL-23/T_H17 axis has been shown in mouse and human models as well as in genetic studies.

IL-23 is a cytokine that shares the p40 subunit with IL-12 and has been linked to autoimmune diseases in both mice and humans.³ It is required for optimal development of T_H17 cells⁴¹ from a committed CD4⁺ T-cell population after exposure to transforming growth factor β1 in combination with other proinflammatory cytokines.^42,43 IL-23 messenger RNA is produced at higher levels in inflammatory psoriatic skin lesions versus uninvolved skin,⁴⁴ and intradermal IL-23 injections in mice produced lesions resembling psoriasis macroscopically and microscopically.⁴⁵ Furthermore, several systemic therapies have been shown to modulate IL-23 levels and correlate with clinical benefit.³ Alterations in the gene for the IL-23 receptor have been shown to be protective for psoriasis,^46-48 and the gene coding for the p40 subunit is associated with psoriasis.^46,47

Type 17 helper T cells produce a number of cytokines, such as IL-22, IL-17A, IL-17F, and IL-26; the latter 3 are considered to be specific to this lineage.⁴² IL-22 acts on outer body barrier tissues, such as the skin, and has antimicrobial activity. Blocking the activity of IL-22 in mice prevented the development of skin lesions,⁴⁹ and psoriasis patients have elevated levels of IL-22 in the skin and blood.^50,51 The IL-17 cytokines induce the expression of proinflammatory cytokines, colony-stimulating factors, and chemokines, and they recruit, mobilize, and activate neutrophils.⁵² IL-17 messenger RNA was found in lesional psoriatic skin but not unaffected skin,⁵³ and cells isolated from the dermis of psoriatic skin have been shown to produce IL-17.⁵⁴ IL-17A is not elevated in the serum of psoriatic patients (unlike other autoimmune diseases),⁵⁵ and it is, therefore, thought that T_H17 cells and IL-17A production are localized to the affected psoriatic skin. Consistent with this concept is the finding that treatments such as cyclosporin A and anti-TNF agents decrease proinflammatory cytokines in lesional skin but not in the periphery.^56-58 These cytokines released by T_H17 cells in addition to those released by T_H1 cells act on keratinocytes and produce epidermal hyperproliferation, acanthosis, and hyperparakeratosis characteristic of psoriasis.³

New therapies have been developed to target the IL-23/T_H17 axis. Ustekinumab is approved for moderate to severe plaque psoriasis. This treatment’s effect may be sustained for up to 3 years, it is generally well tolerated, and it may be useful for patients refractory to anti-TNF therapy such as etanercept.⁵⁹ Briakinumab, another blocker of IL-12 and IL-23, was studied in phase 3 clinical trials, but its development was discontinued due to safety concerns.⁶⁰ Newer drugs targeting the IL-23/T_H17 axis include secukinumab, ixekizumab, brodalumab, guselkumab, and tildrakizumab.

Genetic Basis of Psoriasis

Psoriasis is a disease of overactive immunity in genetically susceptible individuals. Because patients exhibit varying skin phenotypes, extracutaneous manifestations, and disease courses, multiple genes resulting from linkage disequilibrium are believed to be involved in the pathogenesis of psoriasis. A decade of genome-wide linkage scans have established that PSORS1 is the strongest susceptibility locus demonstrable through family linkage studies; PSORS1 is responsible for up to 50% of the genetic component of psoriasis.⁶¹ More recently, HLA-Cw6 has received the most attention as a candidate gene of the PSORS1 susceptibility locus on the MHC class I region on chromosome 6p21.3.⁶² This gene may function in antigen presentation via MHC class I, which aids in the activation of the overactive T cells characteristic of psoriatic inflammation.

Studies involving the IL-23/T_H17 axis have shown genetics to play a role. Individuals may be protected from psoriasis with a nonsynonymous nucleotide substitution in the IL23R gene,^47-49 and certain haplotypes of the IL23R gene are associated with the disease^47,49 in addition to other autoimmune conditions.

Genomic scans have shown additional susceptibility loci for psoriasis on chromosomes 1q21, 3q21, 4q32-35, 16q12, and 17q25. Two regions on chromosome 17q were recently localized via mapping, which demonstrated a 6 megabase pairs separation, thereby indicating independent linkage factors. Genes SLC9A3R1 and NAT9 are present in the first region, while RAPTOR is demonstrated in the second region.⁶³SLC9A3R1 and NAT9 are players that regulate signal transduction, the immunologic synapse, and T-cell growth. RAPTOR is involved in T-cell function and growth pathways. Using these genes as an example, we can predict that the alterations of regulatory genes, even those yet undetermined, can enhance T-cell proliferation and inflammation manifested in psoriasis.

Conclusion

Psoriasis is a complex disease whereby multiple exogenous and endogenous stimuli incite already heightened innate immune responses in genetically predetermined individuals. The disease process is a result of a network of cell types, including T cells, DCs, and keratinocytes that, with the production of cytokines, generate a chronic inflammatory state. Our understanding of these cellular interactions and cytokines originates from developments, some meticulously planned, others serendipitous, in the fields of immunology, cell and molecular biology, and genetics. Such progress has fostered the creation of targeted immune therapy that has demonstrated remarkable efficacy in psoriasis treatment. Further study of the underlying pathophysiology of psoriasis may provide additional targets for therapy.

Increased understanding of the pathophysiology of psoriasis has been one of the driving forces in the development of new therapies. An understanding of the processes involved is important in the optimal management of the disease. The last 30 years of research and clinical practice have revolutionized our understanding of the pathogenesis of psoriasis as the dysregulation of immunity triggered by environmental and genetic stimuli. Psoriasis was originally regarded as a primary disorder of epidermal hyperproliferation. However, experimental models and clinical results from immunomodulating therapies have refined this perspective in conceptualizing psoriasis as a genetically programmed pathologic interaction among resident skin cells; infiltrating immunocytes; and a host of proinflammatory cytokines, chemokines, and growth factors produced by these immunocytes. Two populations of immunocytes and their respective signaling molecules collaborate in the pathogenesis: (1) innate immunocytes, mediated by antigen-presenting cells (APCs)(including natural killer [NK] T lymphocytes, Langerhans cells, and neutrophils), and (2) acquired or adaptive immunocytes, mediated by mature CD4⁺ and CD8⁺ T lymphocytes in the skin. Such dysregulation of immunity and subsequent inflammation is responsible for the development and perpetuation of the clinical plaques and histological inflammatory infiltrate characteristic of psoriasis.

Although psoriasis is considered to be an immune-mediated disease in which intralesional T lymphocytes and their proinflammatory signals trigger primed basal layer keratinocytes to rapidly proliferate, debate and research focus on the stimulus that incites this inflammatory process. Our current understanding considers psoriasis to be triggered by exogenous or endogenous environmental stimuli in genetically susceptible individuals. Such stimuli include group A streptococcal pharyngitis, viremia, allergic drug reactions, antimalarial drugs, lithium, beta-blockers, IFN-α, withdrawal of systemic corticosteroids, local trauma (Köbner phenomenon), and emotional stress. These stimuli correlate with the onset or flares of psoriatic lesions. Psoriasis genetics centers on susceptibility loci and corresponding candidate genes, particularly the psoriasis susceptibility (PSORS) 1 locus on the major histocompatibility complex (MHC) class I region. Current research on the pathogenesis of psoriasis examines the complex interactions among immunologic mechanisms, environmental stimuli, and genetic susceptibility. After discussing the clinical presentation and histopathologic features of psoriasis, we will review the pathophysiology of psoriasis through noteworthy developments, including serendipitous observations, reactions to therapies, clinical trials, and animal model systems that have shaped our view of the disease process. In addition to the classic skin lesions, approximately 23% of psoriasis patients develop psoriatic arthritis, with a 10-year latency after diagnosis of psoriasis.¹

Principles of Immunity

The immune system, intended to protect its host from foreign invaders and unregulated cell growth, employs 2 main effector pathways—the innate and the acquired (or adaptive) immune responses—both of which contribute to the pathophysiology of psoriasis.² Innate immunity responses occur within minutes to hours of antigen exposure but fail to develop memory for when the antigen is encountered again. However, adaptive immunity responses take days to weeks to respond after challenged with an antigen. The adaptive immune cells have the capacity to respond to a greater range of antigens and develop immunologic memory via rearrangement of antigen receptors on B and T cells. These specialized B and T cells can then be promptly mobilized and differentiated into mature effector cells that protect the host from a foreign pathogen.

Innate and adaptive immune responses are highly intertwined; they can initiate, perpetuate, and terminate the immune mechanisms responsible for inflammation. They can modify the nature of the immune response by altering the relative proportions of type 1 (T_H1), type 2 (T_H2), and the more recently discovered type 17 (T_H17) subset of helper T cells and their respective signaling molecules. A T_H1 response is essential for a cellular immunologic reaction to intracellular bacteria and viruses or cellular immunity. A T_H2 response promotes IgE synthesis, eosinophilia, and mast cell maturation for extracellular parasites and helminthes as well as humoral immunity, while a T_H17 response is important for cell-mediated immunity to extracellular bacteria and plays a role in autoimmunity.³ The innate and adaptive immune responses employ common effector molecules such as chemokines and cytokines, which are essential in mediating an immune response.

Implicating Dysregulation of Immunity

Our present appreciation of the pathogenesis of psoriasis is based on the history of trial-and-error therapies; serendipitous discoveries; and the current immune targeting drugs used in a variety of chronic inflammatory conditions, including rheumatoid arthritis, ankylosing spondylitis, and inflammatory bowel disease. Before the mid-1980s, research focused on the hyperproliferative epidermal cells as the primary pathology because a markedly thickened epidermis was indeed demonstrated on histologic specimens. Altered cell-cycle kinetics were thought to be the culprit behind the hyperkeratotic plaques. Thus, initial treatments centered on oncologic and antimitotic therapies used to arrest keratinocyte proliferation with agents such as arsenic, ammoniated mercury, and methotrexate.⁴

However, a paradigm shift from targeting epidermal keratinocytes to immunocyte populations was recognized when a patient receiving cyclosporine to prevent transplant rejection noted clearing of psoriatic lesions in the 1980s.⁵ Cyclosporine was observed to inhibit messenger RNA transcription of T-cell cytokines, thereby implicating immunologic dysregulation, specifically T-cell hyperactivity, in the pathogenesis of psoriasis.⁶ However, the concentrations of oral cyclosporine reached in the epidermis exerted direct effects on keratinocyte proliferation and lymphocyte function in these patients.⁷ Thus, the question was raised as to whether the keratinocytes or the lymphocytes drove the psoriatic plaques. The use of an IL-2 diphtheria toxin-fusion protein, denileukin diftitox, specific for activated T cells with high-affinity IL-2 receptors and nonreactive with keratinocytes, distinguished which cell type was responsible. This targeted T-cell toxin provided clinical and histological clearing of psoriatic plaques. Thus, T lymphocytes rather than keratinocytes were recognized as the definitive driver behind the psoriatic plaques.⁸

Additional studies have demonstrated that treatments that induce prolonged clearing of psoriatic lesions without continuous therapy, such as psoralen plus UVA irradiation, decreased the numbers of T cells in plaques by at least 90%.⁹ However, treatments that require continual therapy for satisfactory clinical results, such as cyclosporine and etretinate, simply suppress T-cell activity and proliferation.^10,11 Further evidence has linked cellular immunity with the pathogenesis of psoriasis, defining it as a T_H1-type disease. Natural killer T cells were shown to be involved through the use of a severe combined immunodeficient mouse model. They were injected into prepsoriatic skin grafted on immunodeficient mice, creating a psoriatic plaque with an immune response showing cytokines from T_H1 cells rather than T_H2 cells.¹² When psoriatic plaques were treated topically with the toll-like receptor 7 agonist imiquimod, aggravation and spreading of the plaques were noted. The exacerbation of psoriasis was accompanied by an induction of lesional T_H1-type interferon produced by plasmacytoid dendritic cell (DC) precursors. Plasmacytoid DCs were observed to compose up to 16% of the total dermal infiltrate in psoriatic skin lesions based on their coexpression of BDCA2 and CD123.¹³ Additionally, cancer patients being treated with interferon alfa experienced induction of psoriasis.¹⁴ Moreover, patients being treated for warts with intralesional interferon alfa developed psoriatic plaques in neighboring prior asymptomatic skin.¹⁵ Patients with psoriasis who were treated with interferon gamma, a T_H1 cytokine type, also developed new plaques correlating with the sites of injection.¹⁶

Intralesional T Lymphocytes

Psoriatic lesions contain a host of innate immunocytes, such as APCs, NK cells, and neutrophils, as well as adaptive T cells and an inflammatory infiltrate. These cells include CD4 and CD8 subtypes in which the CD8⁺ cells predominate in the epidermis, while CD4⁺ cells show preference for the dermis.¹⁷ There are 2 groups of CD8⁺ cells: one group migrates to the epidermis, expressing the integrin CD103, while the other group is found in the dermis but may be headed to or from the epidermis. The CD8⁺ cells residing in the epidermis that express the integrin CD103 are capable of interacting with E-cadherin, which enables these cells to travel to the epidermis and bind resident cells. Immunophenotyping reveals that these mature T cells represent chiefly activated memory cells, including CD2⁺, CD3⁺, CD5⁺, CLA, CD28, and CD45RO⁺.¹⁸ Many of these cells express activation markers such as HLA-DR, CD25, and CD27, in addition to the T-cell receptor (TCR).

T-Lymphocyte Stimulation

Both mature CD4⁺ and CD8⁺ T cells can respond to the peptides presented by APCs. Although the specific antigen that these T cells are reacting to has not yet been elucidated, several antigenic stimuli have been proposed, including self-proteins, microbial pathogens, and microbial superantigens. The premise that self-reactive T lymphocytes may contribute to the disease process is derived from the molecular mimicry theory in which an exuberant immune response to a pathogen produces cross-reactivity with self-antigens.¹⁹ Considering that infections have been associated with the onset of psoriasis, this theory merits consideration. However, it also has been observed that T cells can be activated without antigens or superantigens but rather with direct contact with accessory cells.²⁰ No single theory has clearly emerged. Researchers continue to search for the inciting stimulus that triggers the T lymphocyte and attempt to determine whether T cells are reacting to a self-derived or non–self-derived antigen.

T-Lymphocyte Signaling

T-cell signaling is a highly coordinated process in which T lymphocytes recognize antigens via presentation by mature APCs in the skin rather than the lymphoid tissues. Such APCs expose antigenic peptides via class I or II MHC molecules for which receptors are present on the T-cell surface. The antigen recognition complex at the T-cell and APC interface, in concert with a host of antigen-independent co-stimulatory signals, regulates T-cell signaling and is referred to as the immunologic synapse. The antigen presentation and network of co-stimulatory and adhesion molecules optimize T-cell activation, and dermal DCs release IL-12 and IL-23 to promote a T_H1 and T_H17 response, respectively. The growth factors released by these helper T cells sustain neoangiogenesis, stimulate epidermal hyperproliferation, alter epidermal differentiation, and decrease susceptibility to apoptosis that characterizes the erythematous hypertrophic scaling lesions of psoriasis.²¹ Furthermore, the cytokines produced from the immunologic response, such as tumor necrosis factor (TNF) α, IFN-γ, and IL-2, correspond to cytokines that are upregulated in psoriatic plaques.²²

Integral components of the immunologic synapse complex include co-stimulatory signals such as CD28, CD40, CD80, and CD86, as well as adhesion molecules such as cytotoxic T-lymphocyte antigen 4 and lymphocyte function-associated antigen (LFA) 1, which possess corresponding receptors on the T cell. These molecules play a key role in T-cell signaling, as their disruption has been shown to decrease T-cell responsiveness and associated inflammation. The B7 family of molecules routinely interacts with CD28 T cells to co-stimulate T-cell activation. Cytotoxic T-lymphocyte antigen 4 immunoglobulin, an antibody on the T-cell surface, targets B7 and interferes with signaling between B7 and CD28. In psoriatic patients, this blockade was demonstrated to attenuate the T-cell response and correlated with a clinical and histological decrease in psoriasiform hyperplasia.²³ Biologic therapies that disrupt the LFA-1 component of the immunologic synapse also have demonstrated efficacy in the treatment of psoriasis. Alefacept is a human LFA-3 fusion protein that binds CD2 on T cells and blocks the interaction between LFA-3 on APCs and CD2 on memory CD45RO⁺ T cells and induces apoptosis of such T cells. Efalizumab is a human monoclonal antibody to the CD11 chain of LFA-1 that blocks the interaction between LFA-1 on the T cell and intercellular adhesion molecule 1 on an APC or endothelial cell. Both alefacept and efalizumab, 2 formerly marketed biologic therapies, demonstrated remarkable clinical reduction of psoriatic lesions, and alefacept has been shown to produce disease remission for up to 18 months after discontinuation of therapy.^24-26

NK T Cells

Natural killer T cells represent a subset of CD3⁺ T cells present in psoriatic plaques. Although NK T cells possess a TCR, they differ from T cells by displaying NK receptors comprised of lectin and immunoglobulin families. These cells exhibit remarkable specificity and are activated upon recognition of glycolipids presented by CD1d molecules. This process occurs in contrast to CD4⁺ and CD8⁺ T cells, which, due to their TCR diversity, respond to peptides processed by APCs and displayed on MHC molecules. Natural killer T cells can be classified into 2 subsets: (1) one group that expresses CD4 and preferentially produces T_H1- versus T_H2-type cytokines, and (2) another group that lacks CD4 and CD8 that only produces T_H1-type cytokines. The innate immune system employs NK T cells early in the immune response because of their direct cytotoxicity and rapid production of cytokines such as IFN-γ, which promotes a T_H1 inflammatory response, and IL-4, which promotes the development of T_H2 cells. Excessive or dysfunctional NK T cells have been associated with autoimmune diseases such as multiple sclerosis and inflammatory bowel disease as well as allergic contact dermatitis.^27-29

In psoriasis, NK T cells are located in the epidermis, closely situated to epidermal keratinocytes, which suggests a role for direct antigen presentation. Furthermore, CD1d is overexpressed throughout the epidermis of psoriatic plaques, whereas normally CD1d expression is confined to terminally differentiated keratinocytes. An in vitro study examining cytokine-based inflammation demonstrative of psoriasis treated cultured CD1d-positive keratinocytes with interferon gamma in the presence of alpha-galactosylceramide of the lectin family.³⁰ Interferon gamma was observed to enhance keratinocyte CD1d expression, and subsequently, CD1d-positive keratinocytes were found to activate NK T cells to produce high levels of IFN-γ, while levels of IL-4 remained undetectable. The preferential production of IFN-γ supports a T_H1-mediated mechanism regulated by NK T cells in the immunopathogenesis of psoriasis.

Dendritic Cells

Dendritic cells are APCs that process antigens in the tissues in which they reside, after which they migrate to local lymph nodes where they present their native antigens to T cells. This process allows the T-cell response to be tailored to the appropriate antigens in the corresponding tissues. Immature DCs that capture antigens mature by migrating to the T-cell center of the lymph node where they present their antigens to either MHC molecules or the CD1 family. This presentation results in T-cell proliferation and differentiation that correlates with the required type of T-cell response. Multiple subsets of APCs, including myeloid and plasmacytoid DCs, are highly represented in the epidermis and dermis of psoriatic plaques as compared with normal skin.³¹ Dermal DCs are thought to be responsible for activating both the T_H1 and T_H17 infiltrate by secreting IL-12 and IL-23, respectively. This mixed cellular response secretes cytokines and leads to a cascade of events involving keratinocytes, fibroblasts, endothelial cells, and neutrophils that create the cutaneous lesions seen in psoriasis.³

Although DCs play a pivotal role in eliciting an immune response against a foreign invader, they also contribute to the establishment of tolerance. Throughout their maturation, DCs are continuously sensing their environment, which shapes their production of T_H1- versus T_H2-type cytokines and subsequently the nature of the T-cell response. When challenged with a virus, bacteria, or unchecked cell growth, DCs mature into APCs. However, in the absence of a strong stimulus, DCs fail to mature into APCs and present self-peptides with MHC molecules, thereby creating regulatory T cells involved in peripheral tolerance.³² If this balance between immunogenic APCs and housekeeping T cells is upset, inflammatory conditions such as psoriasis can result.

Cytokines

Cytokines are low-molecular-weight glycoproteins that function as signals to produce inflammation, defense, tissue repair and remodeling, fibrosis, angiogenesis, and restriction of neoplastic growth.³³ Cytokines are produced by immunocytes such as lymphocytes and macrophages as well as nonimmunocytes such as endothelial cells and keratinocytes. Proinflammatory cytokines include IL-1, IL-2, the IL-17 family, IFN-γ, and TNF-α, while anti-inflammatory cytokines include IL-4 and IL-10. A relative preponderance of T_H1 proinflammatory cytokines or an insufficiency of T_H2 anti-inflammatory cytokines induces local inflammation and recruitment of additional immunocyte populations, which produce added cytokines.³⁴ A vicious cycle of inflammation occurs that results in cutaneous manifestations such as a plaque. Psoriatic lesions are characterized by a relative increase of T_H1-type (eg, IL-2, IFN-γ, TNF-α, TNF-β) to T_H2-type (eg, IL-4, IL-5, IL-6, IL-9, IL-10, IL-13) cytokines and an increase in T_H17-type cytokines. Natural killer T cells stimulated by CD1d-overexpressing keratinocytes increase production of proinflammatory IFN-γ without effect on the anti-inflammatory IL-4. In addition to the cytokines produced by T cells, APCs produce IL-18, IL-23, and TNF-α found in the inflammatory infiltrate of psoriatic plaques. Both IL-18 and IL-23 stimulate T_H1 cells to produce IFN-γ, and IL-23 stimulates T_H17 cells. Clearly, a T_H1- and T_H17-type pattern governs the immune effector cells and their respective cytokines present in psoriatic skin.

Tumor Necrosis Factor α

Although a network of cytokines is responsible for the inflammation of psoriasis, TNF-α has been implicated as a master proinflammatory cytokine of the innate immune response due to its widespread targets and sources. Tumor necrosis factor α is produced by activated T cells, keratinocytes, NK cells, macrophages, monocytes, Langerhans APCs, and endothelial cells. Psoriatic lesions demonstrate high concentrations of TNF-α, while the synovial fluid of psoriatic arthritis patients demonstrates elevated concentrations of TNF-α, IL-1, IL-6, and IL-8.³⁴ In psoriasis, TNF-α supports the expression of adhesion molecules (intercellular adhesion molecule 1 and P- and E-selectin), angiogenesis via vascular endothelial growth factor, the synthesis of proinflammatory molecules (IL-1, IL-6, IL-8, and nuclear factor κβ), and keratinocyte hyperproliferation via vasoactive intestinal peptide.³⁵

A role for TNF-α in psoriasis treatment was serendipitously discovered in a trial for Crohn disease in which infliximab, a mouse-human IgG1 anti–TNF-α monoclonal antibody, was observed to clear psoriatic plaques in a patient with both Crohn disease and psoriasis.³⁶ Immunotherapies that target TNF-α, including infliximab, etanercept, and adalimumab, demonstrate notable efficacy in the treatment of psoriasis.^37-39 Tumor necrosis factor α is regarded as the driver of the inflammatory cycle of psoriasis due to its numerous modes of production, capability to amplify other proinflammatory signals, and the efficacy and rapidity with which it produces clinical improvements in psoriasis.

IL-23/T_H17 Axis

A new distinct population of helper T cells has been shown to play an important role in psoriasis. These cells develop with the help of IL-23 (secreted by dermal DCs) and subsequently secrete cytokines such as IL-17; they are, therefore, named T_H17 cells. CD161 is considered a surface marker for these cells.⁴⁰ Strong evidence for this IL-23/T_H17 axis has been shown in mouse and human models as well as in genetic studies.

IL-23 is a cytokine that shares the p40 subunit with IL-12 and has been linked to autoimmune diseases in both mice and humans.³ It is required for optimal development of T_H17 cells⁴¹ from a committed CD4⁺ T-cell population after exposure to transforming growth factor β1 in combination with other proinflammatory cytokines.^42,43 IL-23 messenger RNA is produced at higher levels in inflammatory psoriatic skin lesions versus uninvolved skin,⁴⁴ and intradermal IL-23 injections in mice produced lesions resembling psoriasis macroscopically and microscopically.⁴⁵ Furthermore, several systemic therapies have been shown to modulate IL-23 levels and correlate with clinical benefit.³ Alterations in the gene for the IL-23 receptor have been shown to be protective for psoriasis,^46-48 and the gene coding for the p40 subunit is associated with psoriasis.^46,47

Type 17 helper T cells produce a number of cytokines, such as IL-22, IL-17A, IL-17F, and IL-26; the latter 3 are considered to be specific to this lineage.⁴² IL-22 acts on outer body barrier tissues, such as the skin, and has antimicrobial activity. Blocking the activity of IL-22 in mice prevented the development of skin lesions,⁴⁹ and psoriasis patients have elevated levels of IL-22 in the skin and blood.^50,51 The IL-17 cytokines induce the expression of proinflammatory cytokines, colony-stimulating factors, and chemokines, and they recruit, mobilize, and activate neutrophils.⁵² IL-17 messenger RNA was found in lesional psoriatic skin but not unaffected skin,⁵³ and cells isolated from the dermis of psoriatic skin have been shown to produce IL-17.⁵⁴ IL-17A is not elevated in the serum of psoriatic patients (unlike other autoimmune diseases),⁵⁵ and it is, therefore, thought that T_H17 cells and IL-17A production are localized to the affected psoriatic skin. Consistent with this concept is the finding that treatments such as cyclosporin A and anti-TNF agents decrease proinflammatory cytokines in lesional skin but not in the periphery.^56-58 These cytokines released by T_H17 cells in addition to those released by T_H1 cells act on keratinocytes and produce epidermal hyperproliferation, acanthosis, and hyperparakeratosis characteristic of psoriasis.³

New therapies have been developed to target the IL-23/T_H17 axis. Ustekinumab is approved for moderate to severe plaque psoriasis. This treatment’s effect may be sustained for up to 3 years, it is generally well tolerated, and it may be useful for patients refractory to anti-TNF therapy such as etanercept.⁵⁹ Briakinumab, another blocker of IL-12 and IL-23, was studied in phase 3 clinical trials, but its development was discontinued due to safety concerns.⁶⁰ Newer drugs targeting the IL-23/T_H17 axis include secukinumab, ixekizumab, brodalumab, guselkumab, and tildrakizumab.

Genetic Basis of Psoriasis

Psoriasis is a disease of overactive immunity in genetically susceptible individuals. Because patients exhibit varying skin phenotypes, extracutaneous manifestations, and disease courses, multiple genes resulting from linkage disequilibrium are believed to be involved in the pathogenesis of psoriasis. A decade of genome-wide linkage scans have established that PSORS1 is the strongest susceptibility locus demonstrable through family linkage studies; PSORS1 is responsible for up to 50% of the genetic component of psoriasis.⁶¹ More recently, HLA-Cw6 has received the most attention as a candidate gene of the PSORS1 susceptibility locus on the MHC class I region on chromosome 6p21.3.⁶² This gene may function in antigen presentation via MHC class I, which aids in the activation of the overactive T cells characteristic of psoriatic inflammation.

Studies involving the IL-23/T_H17 axis have shown genetics to play a role. Individuals may be protected from psoriasis with a nonsynonymous nucleotide substitution in the IL23R gene,^47-49 and certain haplotypes of the IL23R gene are associated with the disease^47,49 in addition to other autoimmune conditions.

Genomic scans have shown additional susceptibility loci for psoriasis on chromosomes 1q21, 3q21, 4q32-35, 16q12, and 17q25. Two regions on chromosome 17q were recently localized via mapping, which demonstrated a 6 megabase pairs separation, thereby indicating independent linkage factors. Genes SLC9A3R1 and NAT9 are present in the first region, while RAPTOR is demonstrated in the second region.⁶³SLC9A3R1 and NAT9 are players that regulate signal transduction, the immunologic synapse, and T-cell growth. RAPTOR is involved in T-cell function and growth pathways. Using these genes as an example, we can predict that the alterations of regulatory genes, even those yet undetermined, can enhance T-cell proliferation and inflammation manifested in psoriasis.

Conclusion

Psoriasis is a complex disease whereby multiple exogenous and endogenous stimuli incite already heightened innate immune responses in genetically predetermined individuals. The disease process is a result of a network of cell types, including T cells, DCs, and keratinocytes that, with the production of cytokines, generate a chronic inflammatory state. Our understanding of these cellular interactions and cytokines originates from developments, some meticulously planned, others serendipitous, in the fields of immunology, cell and molecular biology, and genetics. Such progress has fostered the creation of targeted immune therapy that has demonstrated remarkable efficacy in psoriasis treatment. Further study of the underlying pathophysiology of psoriasis may provide additional targets for therapy.

Increased understanding of the pathophysiology of psoriasis has been one of the driving forces in the development of new therapies. An understanding of the processes involved is important in the optimal management of the disease. The last 30 years of research and clinical practice have revolutionized our understanding of the pathogenesis of psoriasis as the dysregulation of immunity triggered by environmental and genetic stimuli. Psoriasis was originally regarded as a primary disorder of epidermal hyperproliferation. However, experimental models and clinical results from immunomodulating therapies have refined this perspective in conceptualizing psoriasis as a genetically programmed pathologic interaction among resident skin cells; infiltrating immunocytes; and a host of proinflammatory cytokines, chemokines, and growth factors produced by these immunocytes. Two populations of immunocytes and their respective signaling molecules collaborate in the pathogenesis: (1) innate immunocytes, mediated by antigen-presenting cells (APCs)(including natural killer [NK] T lymphocytes, Langerhans cells, and neutrophils), and (2) acquired or adaptive immunocytes, mediated by mature CD4⁺ and CD8⁺ T lymphocytes in the skin. Such dysregulation of immunity and subsequent inflammation is responsible for the development and perpetuation of the clinical plaques and histological inflammatory infiltrate characteristic of psoriasis.

Although psoriasis is considered to be an immune-mediated disease in which intralesional T lymphocytes and their proinflammatory signals trigger primed basal layer keratinocytes to rapidly proliferate, debate and research focus on the stimulus that incites this inflammatory process. Our current understanding considers psoriasis to be triggered by exogenous or endogenous environmental stimuli in genetically susceptible individuals. Such stimuli include group A streptococcal pharyngitis, viremia, allergic drug reactions, antimalarial drugs, lithium, beta-blockers, IFN-α, withdrawal of systemic corticosteroids, local trauma (Köbner phenomenon), and emotional stress. These stimuli correlate with the onset or flares of psoriatic lesions. Psoriasis genetics centers on susceptibility loci and corresponding candidate genes, particularly the psoriasis susceptibility (PSORS) 1 locus on the major histocompatibility complex (MHC) class I region. Current research on the pathogenesis of psoriasis examines the complex interactions among immunologic mechanisms, environmental stimuli, and genetic susceptibility. After discussing the clinical presentation and histopathologic features of psoriasis, we will review the pathophysiology of psoriasis through noteworthy developments, including serendipitous observations, reactions to therapies, clinical trials, and animal model systems that have shaped our view of the disease process. In addition to the classic skin lesions, approximately 23% of psoriasis patients develop psoriatic arthritis, with a 10-year latency after diagnosis of psoriasis.¹

Principles of Immunity

The immune system, intended to protect its host from foreign invaders and unregulated cell growth, employs 2 main effector pathways—the innate and the acquired (or adaptive) immune responses—both of which contribute to the pathophysiology of psoriasis.² Innate immunity responses occur within minutes to hours of antigen exposure but fail to develop memory for when the antigen is encountered again. However, adaptive immunity responses take days to weeks to respond after challenged with an antigen. The adaptive immune cells have the capacity to respond to a greater range of antigens and develop immunologic memory via rearrangement of antigen receptors on B and T cells. These specialized B and T cells can then be promptly mobilized and differentiated into mature effector cells that protect the host from a foreign pathogen.

Innate and adaptive immune responses are highly intertwined; they can initiate, perpetuate, and terminate the immune mechanisms responsible for inflammation. They can modify the nature of the immune response by altering the relative proportions of type 1 (T_H1), type 2 (T_H2), and the more recently discovered type 17 (T_H17) subset of helper T cells and their respective signaling molecules. A T_H1 response is essential for a cellular immunologic reaction to intracellular bacteria and viruses or cellular immunity. A T_H2 response promotes IgE synthesis, eosinophilia, and mast cell maturation for extracellular parasites and helminthes as well as humoral immunity, while a T_H17 response is important for cell-mediated immunity to extracellular bacteria and plays a role in autoimmunity.³ The innate and adaptive immune responses employ common effector molecules such as chemokines and cytokines, which are essential in mediating an immune response.

Implicating Dysregulation of Immunity

Our present appreciation of the pathogenesis of psoriasis is based on the history of trial-and-error therapies; serendipitous discoveries; and the current immune targeting drugs used in a variety of chronic inflammatory conditions, including rheumatoid arthritis, ankylosing spondylitis, and inflammatory bowel disease. Before the mid-1980s, research focused on the hyperproliferative epidermal cells as the primary pathology because a markedly thickened epidermis was indeed demonstrated on histologic specimens. Altered cell-cycle kinetics were thought to be the culprit behind the hyperkeratotic plaques. Thus, initial treatments centered on oncologic and antimitotic therapies used to arrest keratinocyte proliferation with agents such as arsenic, ammoniated mercury, and methotrexate.⁴

However, a paradigm shift from targeting epidermal keratinocytes to immunocyte populations was recognized when a patient receiving cyclosporine to prevent transplant rejection noted clearing of psoriatic lesions in the 1980s.⁵ Cyclosporine was observed to inhibit messenger RNA transcription of T-cell cytokines, thereby implicating immunologic dysregulation, specifically T-cell hyperactivity, in the pathogenesis of psoriasis.⁶ However, the concentrations of oral cyclosporine reached in the epidermis exerted direct effects on keratinocyte proliferation and lymphocyte function in these patients.⁷ Thus, the question was raised as to whether the keratinocytes or the lymphocytes drove the psoriatic plaques. The use of an IL-2 diphtheria toxin-fusion protein, denileukin diftitox, specific for activated T cells with high-affinity IL-2 receptors and nonreactive with keratinocytes, distinguished which cell type was responsible. This targeted T-cell toxin provided clinical and histological clearing of psoriatic plaques. Thus, T lymphocytes rather than keratinocytes were recognized as the definitive driver behind the psoriatic plaques.⁸

Additional studies have demonstrated that treatments that induce prolonged clearing of psoriatic lesions without continuous therapy, such as psoralen plus UVA irradiation, decreased the numbers of T cells in plaques by at least 90%.⁹ However, treatments that require continual therapy for satisfactory clinical results, such as cyclosporine and etretinate, simply suppress T-cell activity and proliferation.^10,11 Further evidence has linked cellular immunity with the pathogenesis of psoriasis, defining it as a T_H1-type disease. Natural killer T cells were shown to be involved through the use of a severe combined immunodeficient mouse model. They were injected into prepsoriatic skin grafted on immunodeficient mice, creating a psoriatic plaque with an immune response showing cytokines from T_H1 cells rather than T_H2 cells.¹² When psoriatic plaques were treated topically with the toll-like receptor 7 agonist imiquimod, aggravation and spreading of the plaques were noted. The exacerbation of psoriasis was accompanied by an induction of lesional T_H1-type interferon produced by plasmacytoid dendritic cell (DC) precursors. Plasmacytoid DCs were observed to compose up to 16% of the total dermal infiltrate in psoriatic skin lesions based on their coexpression of BDCA2 and CD123.¹³ Additionally, cancer patients being treated with interferon alfa experienced induction of psoriasis.¹⁴ Moreover, patients being treated for warts with intralesional interferon alfa developed psoriatic plaques in neighboring prior asymptomatic skin.¹⁵ Patients with psoriasis who were treated with interferon gamma, a T_H1 cytokine type, also developed new plaques correlating with the sites of injection.¹⁶

Intralesional T Lymphocytes

Psoriatic lesions contain a host of innate immunocytes, such as APCs, NK cells, and neutrophils, as well as adaptive T cells and an inflammatory infiltrate. These cells include CD4 and CD8 subtypes in which the CD8⁺ cells predominate in the epidermis, while CD4⁺ cells show preference for the dermis.¹⁷ There are 2 groups of CD8⁺ cells: one group migrates to the epidermis, expressing the integrin CD103, while the other group is found in the dermis but may be headed to or from the epidermis. The CD8⁺ cells residing in the epidermis that express the integrin CD103 are capable of interacting with E-cadherin, which enables these cells to travel to the epidermis and bind resident cells. Immunophenotyping reveals that these mature T cells represent chiefly activated memory cells, including CD2⁺, CD3⁺, CD5⁺, CLA, CD28, and CD45RO⁺.¹⁸ Many of these cells express activation markers such as HLA-DR, CD25, and CD27, in addition to the T-cell receptor (TCR).

T-Lymphocyte Stimulation

Both mature CD4⁺ and CD8⁺ T cells can respond to the peptides presented by APCs. Although the specific antigen that these T cells are reacting to has not yet been elucidated, several antigenic stimuli have been proposed, including self-proteins, microbial pathogens, and microbial superantigens. The premise that self-reactive T lymphocytes may contribute to the disease process is derived from the molecular mimicry theory in which an exuberant immune response to a pathogen produces cross-reactivity with self-antigens.¹⁹ Considering that infections have been associated with the onset of psoriasis, this theory merits consideration. However, it also has been observed that T cells can be activated without antigens or superantigens but rather with direct contact with accessory cells.²⁰ No single theory has clearly emerged. Researchers continue to search for the inciting stimulus that triggers the T lymphocyte and attempt to determine whether T cells are reacting to a self-derived or non–self-derived antigen.

T-Lymphocyte Signaling

T-cell signaling is a highly coordinated process in which T lymphocytes recognize antigens via presentation by mature APCs in the skin rather than the lymphoid tissues. Such APCs expose antigenic peptides via class I or II MHC molecules for which receptors are present on the T-cell surface. The antigen recognition complex at the T-cell and APC interface, in concert with a host of antigen-independent co-stimulatory signals, regulates T-cell signaling and is referred to as the immunologic synapse. The antigen presentation and network of co-stimulatory and adhesion molecules optimize T-cell activation, and dermal DCs release IL-12 and IL-23 to promote a T_H1 and T_H17 response, respectively. The growth factors released by these helper T cells sustain neoangiogenesis, stimulate epidermal hyperproliferation, alter epidermal differentiation, and decrease susceptibility to apoptosis that characterizes the erythematous hypertrophic scaling lesions of psoriasis.²¹ Furthermore, the cytokines produced from the immunologic response, such as tumor necrosis factor (TNF) α, IFN-γ, and IL-2, correspond to cytokines that are upregulated in psoriatic plaques.²²

Integral components of the immunologic synapse complex include co-stimulatory signals such as CD28, CD40, CD80, and CD86, as well as adhesion molecules such as cytotoxic T-lymphocyte antigen 4 and lymphocyte function-associated antigen (LFA) 1, which possess corresponding receptors on the T cell. These molecules play a key role in T-cell signaling, as their disruption has been shown to decrease T-cell responsiveness and associated inflammation. The B7 family of molecules routinely interacts with CD28 T cells to co-stimulate T-cell activation. Cytotoxic T-lymphocyte antigen 4 immunoglobulin, an antibody on the T-cell surface, targets B7 and interferes with signaling between B7 and CD28. In psoriatic patients, this blockade was demonstrated to attenuate the T-cell response and correlated with a clinical and histological decrease in psoriasiform hyperplasia.²³ Biologic therapies that disrupt the LFA-1 component of the immunologic synapse also have demonstrated efficacy in the treatment of psoriasis. Alefacept is a human LFA-3 fusion protein that binds CD2 on T cells and blocks the interaction between LFA-3 on APCs and CD2 on memory CD45RO⁺ T cells and induces apoptosis of such T cells. Efalizumab is a human monoclonal antibody to the CD11 chain of LFA-1 that blocks the interaction between LFA-1 on the T cell and intercellular adhesion molecule 1 on an APC or endothelial cell. Both alefacept and efalizumab, 2 formerly marketed biologic therapies, demonstrated remarkable clinical reduction of psoriatic lesions, and alefacept has been shown to produce disease remission for up to 18 months after discontinuation of therapy.^24-26

NK T Cells

Natural killer T cells represent a subset of CD3⁺ T cells present in psoriatic plaques. Although NK T cells possess a TCR, they differ from T cells by displaying NK receptors comprised of lectin and immunoglobulin families. These cells exhibit remarkable specificity and are activated upon recognition of glycolipids presented by CD1d molecules. This process occurs in contrast to CD4⁺ and CD8⁺ T cells, which, due to their TCR diversity, respond to peptides processed by APCs and displayed on MHC molecules. Natural killer T cells can be classified into 2 subsets: (1) one group that expresses CD4 and preferentially produces T_H1- versus T_H2-type cytokines, and (2) another group that lacks CD4 and CD8 that only produces T_H1-type cytokines. The innate immune system employs NK T cells early in the immune response because of their direct cytotoxicity and rapid production of cytokines such as IFN-γ, which promotes a T_H1 inflammatory response, and IL-4, which promotes the development of T_H2 cells. Excessive or dysfunctional NK T cells have been associated with autoimmune diseases such as multiple sclerosis and inflammatory bowel disease as well as allergic contact dermatitis.^27-29

In psoriasis, NK T cells are located in the epidermis, closely situated to epidermal keratinocytes, which suggests a role for direct antigen presentation. Furthermore, CD1d is overexpressed throughout the epidermis of psoriatic plaques, whereas normally CD1d expression is confined to terminally differentiated keratinocytes. An in vitro study examining cytokine-based inflammation demonstrative of psoriasis treated cultured CD1d-positive keratinocytes with interferon gamma in the presence of alpha-galactosylceramide of the lectin family.³⁰ Interferon gamma was observed to enhance keratinocyte CD1d expression, and subsequently, CD1d-positive keratinocytes were found to activate NK T cells to produce high levels of IFN-γ, while levels of IL-4 remained undetectable. The preferential production of IFN-γ supports a T_H1-mediated mechanism regulated by NK T cells in the immunopathogenesis of psoriasis.

Dendritic Cells

Dendritic cells are APCs that process antigens in the tissues in which they reside, after which they migrate to local lymph nodes where they present their native antigens to T cells. This process allows the T-cell response to be tailored to the appropriate antigens in the corresponding tissues. Immature DCs that capture antigens mature by migrating to the T-cell center of the lymph node where they present their antigens to either MHC molecules or the CD1 family. This presentation results in T-cell proliferation and differentiation that correlates with the required type of T-cell response. Multiple subsets of APCs, including myeloid and plasmacytoid DCs, are highly represented in the epidermis and dermis of psoriatic plaques as compared with normal skin.³¹ Dermal DCs are thought to be responsible for activating both the T_H1 and T_H17 infiltrate by secreting IL-12 and IL-23, respectively. This mixed cellular response secretes cytokines and leads to a cascade of events involving keratinocytes, fibroblasts, endothelial cells, and neutrophils that create the cutaneous lesions seen in psoriasis.³

Although DCs play a pivotal role in eliciting an immune response against a foreign invader, they also contribute to the establishment of tolerance. Throughout their maturation, DCs are continuously sensing their environment, which shapes their production of T_H1- versus T_H2-type cytokines and subsequently the nature of the T-cell response. When challenged with a virus, bacteria, or unchecked cell growth, DCs mature into APCs. However, in the absence of a strong stimulus, DCs fail to mature into APCs and present self-peptides with MHC molecules, thereby creating regulatory T cells involved in peripheral tolerance.³² If this balance between immunogenic APCs and housekeeping T cells is upset, inflammatory conditions such as psoriasis can result.

Cytokines

Cytokines are low-molecular-weight glycoproteins that function as signals to produce inflammation, defense, tissue repair and remodeling, fibrosis, angiogenesis, and restriction of neoplastic growth.³³ Cytokines are produced by immunocytes such as lymphocytes and macrophages as well as nonimmunocytes such as endothelial cells and keratinocytes. Proinflammatory cytokines include IL-1, IL-2, the IL-17 family, IFN-γ, and TNF-α, while anti-inflammatory cytokines include IL-4 and IL-10. A relative preponderance of T_H1 proinflammatory cytokines or an insufficiency of T_H2 anti-inflammatory cytokines induces local inflammation and recruitment of additional immunocyte populations, which produce added cytokines.³⁴ A vicious cycle of inflammation occurs that results in cutaneous manifestations such as a plaque. Psoriatic lesions are characterized by a relative increase of T_H1-type (eg, IL-2, IFN-γ, TNF-α, TNF-β) to T_H2-type (eg, IL-4, IL-5, IL-6, IL-9, IL-10, IL-13) cytokines and an increase in T_H17-type cytokines. Natural killer T cells stimulated by CD1d-overexpressing keratinocytes increase production of proinflammatory IFN-γ without effect on the anti-inflammatory IL-4. In addition to the cytokines produced by T cells, APCs produce IL-18, IL-23, and TNF-α found in the inflammatory infiltrate of psoriatic plaques. Both IL-18 and IL-23 stimulate T_H1 cells to produce IFN-γ, and IL-23 stimulates T_H17 cells. Clearly, a T_H1- and T_H17-type pattern governs the immune effector cells and their respective cytokines present in psoriatic skin.

Tumor Necrosis Factor α

Although a network of cytokines is responsible for the inflammation of psoriasis, TNF-α has been implicated as a master proinflammatory cytokine of the innate immune response due to its widespread targets and sources. Tumor necrosis factor α is produced by activated T cells, keratinocytes, NK cells, macrophages, monocytes, Langerhans APCs, and endothelial cells. Psoriatic lesions demonstrate high concentrations of TNF-α, while the synovial fluid of psoriatic arthritis patients demonstrates elevated concentrations of TNF-α, IL-1, IL-6, and IL-8.³⁴ In psoriasis, TNF-α supports the expression of adhesion molecules (intercellular adhesion molecule 1 and P- and E-selectin), angiogenesis via vascular endothelial growth factor, the synthesis of proinflammatory molecules (IL-1, IL-6, IL-8, and nuclear factor κβ), and keratinocyte hyperproliferation via vasoactive intestinal peptide.³⁵

A role for TNF-α in psoriasis treatment was serendipitously discovered in a trial for Crohn disease in which infliximab, a mouse-human IgG1 anti–TNF-α monoclonal antibody, was observed to clear psoriatic plaques in a patient with both Crohn disease and psoriasis.³⁶ Immunotherapies that target TNF-α, including infliximab, etanercept, and adalimumab, demonstrate notable efficacy in the treatment of psoriasis.^37-39 Tumor necrosis factor α is regarded as the driver of the inflammatory cycle of psoriasis due to its numerous modes of production, capability to amplify other proinflammatory signals, and the efficacy and rapidity with which it produces clinical improvements in psoriasis.

IL-23/T_H17 Axis

A new distinct population of helper T cells has been shown to play an important role in psoriasis. These cells develop with the help of IL-23 (secreted by dermal DCs) and subsequently secrete cytokines such as IL-17; they are, therefore, named T_H17 cells. CD161 is considered a surface marker for these cells.⁴⁰ Strong evidence for this IL-23/T_H17 axis has been shown in mouse and human models as well as in genetic studies.

IL-23 is a cytokine that shares the p40 subunit with IL-12 and has been linked to autoimmune diseases in both mice and humans.³ It is required for optimal development of T_H17 cells⁴¹ from a committed CD4⁺ T-cell population after exposure to transforming growth factor β1 in combination with other proinflammatory cytokines.^42,43 IL-23 messenger RNA is produced at higher levels in inflammatory psoriatic skin lesions versus uninvolved skin,⁴⁴ and intradermal IL-23 injections in mice produced lesions resembling psoriasis macroscopically and microscopically.⁴⁵ Furthermore, several systemic therapies have been shown to modulate IL-23 levels and correlate with clinical benefit.³ Alterations in the gene for the IL-23 receptor have been shown to be protective for psoriasis,^46-48 and the gene coding for the p40 subunit is associated with psoriasis.^46,47

Type 17 helper T cells produce a number of cytokines, such as IL-22, IL-17A, IL-17F, and IL-26; the latter 3 are considered to be specific to this lineage.⁴² IL-22 acts on outer body barrier tissues, such as the skin, and has antimicrobial activity. Blocking the activity of IL-22 in mice prevented the development of skin lesions,⁴⁹ and psoriasis patients have elevated levels of IL-22 in the skin and blood.^50,51 The IL-17 cytokines induce the expression of proinflammatory cytokines, colony-stimulating factors, and chemokines, and they recruit, mobilize, and activate neutrophils.⁵² IL-17 messenger RNA was found in lesional psoriatic skin but not unaffected skin,⁵³ and cells isolated from the dermis of psoriatic skin have been shown to produce IL-17.⁵⁴ IL-17A is not elevated in the serum of psoriatic patients (unlike other autoimmune diseases),⁵⁵ and it is, therefore, thought that T_H17 cells and IL-17A production are localized to the affected psoriatic skin. Consistent with this concept is the finding that treatments such as cyclosporin A and anti-TNF agents decrease proinflammatory cytokines in lesional skin but not in the periphery.^56-58 These cytokines released by T_H17 cells in addition to those released by T_H1 cells act on keratinocytes and produce epidermal hyperproliferation, acanthosis, and hyperparakeratosis characteristic of psoriasis.³

New therapies have been developed to target the IL-23/T_H17 axis. Ustekinumab is approved for moderate to severe plaque psoriasis. This treatment’s effect may be sustained for up to 3 years, it is generally well tolerated, and it may be useful for patients refractory to anti-TNF therapy such as etanercept.⁵⁹ Briakinumab, another blocker of IL-12 and IL-23, was studied in phase 3 clinical trials, but its development was discontinued due to safety concerns.⁶⁰ Newer drugs targeting the IL-23/T_H17 axis include secukinumab, ixekizumab, brodalumab, guselkumab, and tildrakizumab.

Genetic Basis of Psoriasis

Psoriasis is a disease of overactive immunity in genetically susceptible individuals. Because patients exhibit varying skin phenotypes, extracutaneous manifestations, and disease courses, multiple genes resulting from linkage disequilibrium are believed to be involved in the pathogenesis of psoriasis. A decade of genome-wide linkage scans have established that PSORS1 is the strongest susceptibility locus demonstrable through family linkage studies; PSORS1 is responsible for up to 50% of the genetic component of psoriasis.⁶¹ More recently, HLA-Cw6 has received the most attention as a candidate gene of the PSORS1 susceptibility locus on the MHC class I region on chromosome 6p21.3.⁶² This gene may function in antigen presentation via MHC class I, which aids in the activation of the overactive T cells characteristic of psoriatic inflammation.

Studies involving the IL-23/T_H17 axis have shown genetics to play a role. Individuals may be protected from psoriasis with a nonsynonymous nucleotide substitution in the IL23R gene,^47-49 and certain haplotypes of the IL23R gene are associated with the disease^47,49 in addition to other autoimmune conditions.

Genomic scans have shown additional susceptibility loci for psoriasis on chromosomes 1q21, 3q21, 4q32-35, 16q12, and 17q25. Two regions on chromosome 17q were recently localized via mapping, which demonstrated a 6 megabase pairs separation, thereby indicating independent linkage factors. Genes SLC9A3R1 and NAT9 are present in the first region, while RAPTOR is demonstrated in the second region.⁶³SLC9A3R1 and NAT9 are players that regulate signal transduction, the immunologic synapse, and T-cell growth. RAPTOR is involved in T-cell function and growth pathways. Using these genes as an example, we can predict that the alterations of regulatory genes, even those yet undetermined, can enhance T-cell proliferation and inflammation manifested in psoriasis.

Conclusion

Psoriasis is a complex disease whereby multiple exogenous and endogenous stimuli incite already heightened innate immune responses in genetically predetermined individuals. The disease process is a result of a network of cell types, including T cells, DCs, and keratinocytes that, with the production of cytokines, generate a chronic inflammatory state. Our understanding of these cellular interactions and cytokines originates from developments, some meticulously planned, others serendipitous, in the fields of immunology, cell and molecular biology, and genetics. Such progress has fostered the creation of targeted immune therapy that has demonstrated remarkable efficacy in psoriasis treatment. Further study of the underlying pathophysiology of psoriasis may provide additional targets for therapy.

This special issue is dedicated to resident education on psoriasis. With that in mind, we hope to address many topics of interest to those in training. Over the years, diet has been a hot topic among psoriasis patients. They want to know how diet affects psoriasis and what changes can be made to their diet to improve their condition. Although they have expected specific answers, my response has usually been that they should, of course, eat an overall healthy and balanced diet, and lose weight if necessary. I have continued, however, that no specific diet has been recommended. However, now we have some information that may start to give us some answers.

The Mediterranean diet has been regarded as a healthy regimen.¹ This diet emphasizes eating primarily plant-based foods, such as fruits and vegetables; whole grains; legumes; and nuts. Other recommendations include replacing butter with healthy fats such as olive oil and canola oil, using herbs and spices instead of salt to flavor foods, and limiting red meat to no more than a few times a month.¹

As we know, psoriasis is a chronic inflammatory disease. The Mediterranean diet has been shown to reduce chronic inflammation and has a positive effect on the risk for metabolic syndrome and cardiovascular events.¹ Phan et al¹ hypothesized a positive effect of the Mediterranean diet on psoriasis. They performed a study to assess the association between a score that reflects the adhesion to a Mediterranean diet (MEDI-LITE) and the onset and/or severity of psoriasis.¹

The NutriNet-Santé program is an ongoing, observational, web-based questionnaire cohort study launched in France in May 2009.¹ Data were collected and analyzed between April 2017 and June 2017. Individuals with psoriasis were identified utilizing a validated online questionnaire and then categorized by disease severity into 1 of 3 groups: severe psoriasis, nonsevere psoriasis, and psoriasis free.¹

During the initial 2 years of participation in the cohort, data on dietary intake (including alcohol) were gathered to calculate the MEDI-LITE score, ranging from 0 (no adherence) to 18 (maximum adherence).¹ Of the 158,361 total web-based participants, 35,735 (23%) replied to the psoriasis questionnaire.¹ Of the respondents, 3557 (10%) individuals reported having psoriasis. The condition was severe in 878 cases (24.7%), and 299 (8.4%) incident cases were recorded (cases occurring >2 years after participant inclusion in the cohort). After adjustment for confounding factors, the investigators found a significant inverse relationship between the MEDI-LITE score and having severe psoriasis (odds ratio [OR], 0.71; 95% CI, 0.55-0.92 for the MEDI-LITE score’s second tertile [score of 8 to 9]; and OR, 0.78; 95% CI, 0.59-1.01 for the third tertile [score of 10 to 18]).¹

The authors noted that patients with severe psoriasis displayed low levels of adherence to the Mediterranean diet.¹ They commented that this finding supports the hypothesis that the Mediterranean diet may slow the progression of psoriasis. If these findings are confirmed, adherence to a Mediterranean diet should be integrated into the routine management of moderate to severe psoriasis.¹ These findings are by no means definitive, but it is a first step in helping us define more specific dietary recommendations for psoriasis.

This issue includes several articles looking at various facets of psoriasis important to residents, including the pathophysiology of psoriasis,² treatment approach using biologic therapies,³ risk factors and triggers for psoriasis,⁴ and the psychosocial impact of psoriasis.⁵ We hope that you find this issue enjoyable and informative.

This special issue is dedicated to resident education on psoriasis. With that in mind, we hope to address many topics of interest to those in training. Over the years, diet has been a hot topic among psoriasis patients. They want to know how diet affects psoriasis and what changes can be made to their diet to improve their condition. Although they have expected specific answers, my response has usually been that they should, of course, eat an overall healthy and balanced diet, and lose weight if necessary. I have continued, however, that no specific diet has been recommended. However, now we have some information that may start to give us some answers.

The Mediterranean diet has been regarded as a healthy regimen.¹ This diet emphasizes eating primarily plant-based foods, such as fruits and vegetables; whole grains; legumes; and nuts. Other recommendations include replacing butter with healthy fats such as olive oil and canola oil, using herbs and spices instead of salt to flavor foods, and limiting red meat to no more than a few times a month.¹

As we know, psoriasis is a chronic inflammatory disease. The Mediterranean diet has been shown to reduce chronic inflammation and has a positive effect on the risk for metabolic syndrome and cardiovascular events.¹ Phan et al¹ hypothesized a positive effect of the Mediterranean diet on psoriasis. They performed a study to assess the association between a score that reflects the adhesion to a Mediterranean diet (MEDI-LITE) and the onset and/or severity of psoriasis.¹

The NutriNet-Santé program is an ongoing, observational, web-based questionnaire cohort study launched in France in May 2009.¹ Data were collected and analyzed between April 2017 and June 2017. Individuals with psoriasis were identified utilizing a validated online questionnaire and then categorized by disease severity into 1 of 3 groups: severe psoriasis, nonsevere psoriasis, and psoriasis free.¹

During the initial 2 years of participation in the cohort, data on dietary intake (including alcohol) were gathered to calculate the MEDI-LITE score, ranging from 0 (no adherence) to 18 (maximum adherence).¹ Of the 158,361 total web-based participants, 35,735 (23%) replied to the psoriasis questionnaire.¹ Of the respondents, 3557 (10%) individuals reported having psoriasis. The condition was severe in 878 cases (24.7%), and 299 (8.4%) incident cases were recorded (cases occurring >2 years after participant inclusion in the cohort). After adjustment for confounding factors, the investigators found a significant inverse relationship between the MEDI-LITE score and having severe psoriasis (odds ratio [OR], 0.71; 95% CI, 0.55-0.92 for the MEDI-LITE score’s second tertile [score of 8 to 9]; and OR, 0.78; 95% CI, 0.59-1.01 for the third tertile [score of 10 to 18]).¹

The authors noted that patients with severe psoriasis displayed low levels of adherence to the Mediterranean diet.¹ They commented that this finding supports the hypothesis that the Mediterranean diet may slow the progression of psoriasis. If these findings are confirmed, adherence to a Mediterranean diet should be integrated into the routine management of moderate to severe psoriasis.¹ These findings are by no means definitive, but it is a first step in helping us define more specific dietary recommendations for psoriasis.

This issue includes several articles looking at various facets of psoriasis important to residents, including the pathophysiology of psoriasis,² treatment approach using biologic therapies,³ risk factors and triggers for psoriasis,⁴ and the psychosocial impact of psoriasis.⁵ We hope that you find this issue enjoyable and informative.

This special issue is dedicated to resident education on psoriasis. With that in mind, we hope to address many topics of interest to those in training. Over the years, diet has been a hot topic among psoriasis patients. They want to know how diet affects psoriasis and what changes can be made to their diet to improve their condition. Although they have expected specific answers, my response has usually been that they should, of course, eat an overall healthy and balanced diet, and lose weight if necessary. I have continued, however, that no specific diet has been recommended. However, now we have some information that may start to give us some answers.

The Mediterranean diet has been regarded as a healthy regimen.¹ This diet emphasizes eating primarily plant-based foods, such as fruits and vegetables; whole grains; legumes; and nuts. Other recommendations include replacing butter with healthy fats such as olive oil and canola oil, using herbs and spices instead of salt to flavor foods, and limiting red meat to no more than a few times a month.¹

As we know, psoriasis is a chronic inflammatory disease. The Mediterranean diet has been shown to reduce chronic inflammation and has a positive effect on the risk for metabolic syndrome and cardiovascular events.¹ Phan et al¹ hypothesized a positive effect of the Mediterranean diet on psoriasis. They performed a study to assess the association between a score that reflects the adhesion to a Mediterranean diet (MEDI-LITE) and the onset and/or severity of psoriasis.¹

The NutriNet-Santé program is an ongoing, observational, web-based questionnaire cohort study launched in France in May 2009.¹ Data were collected and analyzed between April 2017 and June 2017. Individuals with psoriasis were identified utilizing a validated online questionnaire and then categorized by disease severity into 1 of 3 groups: severe psoriasis, nonsevere psoriasis, and psoriasis free.¹

During the initial 2 years of participation in the cohort, data on dietary intake (including alcohol) were gathered to calculate the MEDI-LITE score, ranging from 0 (no adherence) to 18 (maximum adherence).¹ Of the 158,361 total web-based participants, 35,735 (23%) replied to the psoriasis questionnaire.¹ Of the respondents, 3557 (10%) individuals reported having psoriasis. The condition was severe in 878 cases (24.7%), and 299 (8.4%) incident cases were recorded (cases occurring >2 years after participant inclusion in the cohort). After adjustment for confounding factors, the investigators found a significant inverse relationship between the MEDI-LITE score and having severe psoriasis (odds ratio [OR], 0.71; 95% CI, 0.55-0.92 for the MEDI-LITE score’s second tertile [score of 8 to 9]; and OR, 0.78; 95% CI, 0.59-1.01 for the third tertile [score of 10 to 18]).¹

The authors noted that patients with severe psoriasis displayed low levels of adherence to the Mediterranean diet.¹ They commented that this finding supports the hypothesis that the Mediterranean diet may slow the progression of psoriasis. If these findings are confirmed, adherence to a Mediterranean diet should be integrated into the routine management of moderate to severe psoriasis.¹ These findings are by no means definitive, but it is a first step in helping us define more specific dietary recommendations for psoriasis.

This issue includes several articles looking at various facets of psoriasis important to residents, including the pathophysiology of psoriasis,² treatment approach using biologic therapies,³ risk factors and triggers for psoriasis,⁴ and the psychosocial impact of psoriasis.⁵ We hope that you find this issue enjoyable and informative.

Psoriasis patients are more vulnerable to systemic infections, including influenza-related pneumonia, but a new study shows that they are less likely to receive the influenza vaccine than patients with RA.

Jovanmandic/Thinkstock

Vaccination rates were higher in psoriasis patients aged over 50 years, those who were female, and those with other chronic medical conditions, however.

Megan H. Noe, MD, of the department of dermatology at the University of Pennsylvania, Philadelphia, and her coauthors referred to recent evidence suggesting that psoriasis involves systemic inflammation that increase the risk of comorbidities and that hospitalization rates for serious infections, including lower respiratory tract infections and pneumonia, are higher among adults with psoriasis than those who do not have psoriasis.

To compare influenza vaccination rates in psoriasis patients with those among patients with other chronic diseases, they conducted a cohort study, drawing from administrative and commercial claims data from OptumInsight Clinformatics Data Mart. They examined all adult patients with psoriasis, RA, or chronic hypertension who required oral antihypertensive medication. The study population included individuals tracked during the 2010-2011 flu season and 24 months prior (September 2008 to March 2011). This year was chosen because it was labeled as a “typical” season by the Centers for Disease Control and Prevention.

The primary outcome was a claim for an influenza vaccine, and covariates included age, length of residency, gender, and a clinical history of a range of conditions known to be associated with greater risk of influenza complications.

The population included 17,078 patients with psoriasis, 21,832 with RA, and 496,972 with chronic hypertension. After controlling for sex and age, the probability of getting a flu vaccine was similar between psoriasis and hypertension patients, but RA patients were more likely to be vaccinated than patients with psoriasis (odds ratio, 1.08; 95% confidence interval, 1.03-1.13). But the likelihood varied with age: 30-year-old patients with RA were more likely than a 30-year-old psoriasis patient to get a flu shot (OR, 1.30; 95% CI, 1.18-1.45), while a 70-year-old patient with RA was about as likely to get the flu vaccine as a 70-year-old patient with psoriasis.

Female psoriasis patients were more likely to get a flu shot than males (OR, 1.29; 95% CI, 1.20-1.38). Among the psoriasis patients, having some medical comorbidities were linked to a greater likelihood of being vaccinated, including asthma (OR, 1.58; 95% CI, 1.40-1.77), chronic liver disease (OR, 1.23; 95%, 1.03-1.47), diabetes (OR, 1.48; 95% CI, 1.36-1.63), HIV (OR, 3.68; 95% CI, 2.06-6.57), history of malignancy (OR, 1.21; 95% CI, 1.09-1.34), and psoriatic arthritis (OR, 1.40; 95% CI, 1.25-1.58).

There was no association between the use of an oral systemic therapy or biologic treatment and vaccination rates.

The authors suggested that psoriasis patients, especially younger ones, may not get adequate counseling on the value of the flu vaccine from their physicians. Studies have shown that, among the American public, health care providers are the most influential source of information about the flu vaccine. Among younger patients, the dermatologist may be a psoriasis patient’s primary health care provider, so it is important for dermatologists to counsel patients about the recommended vaccines, the authors wrote.

“Further research understanding why adults with psoriasis do not receive recommended vaccinations will help to create targeted interventions to improve vaccination rates and decrease hospitalizations in adults with psoriasis,” they concluded.

The study relied on administrative claims, so the results may not be generalizable to patients with insurance types other than those in the database or who are uninsured, the authors noted.

This study was funded by the National Psoriasis Foundation, the Dermatology Foundation, and the National Institute of Arthritis and Musculoskeletal and Skin Diseases. Dr. Noe and three other authors did not report any disclosures, the fifth author reported multiple disclosures related to various pharmaceutical companies.

SOURCE: Noe MH et al. J Invest Dermatol. 2018 Oct 10. doi: 10.1016/j.jid.2018.09.012.
 

Psoriasis patients are more vulnerable to systemic infections, including influenza-related pneumonia, but a new study shows that they are less likely to receive the influenza vaccine than patients with RA.

Jovanmandic/Thinkstock

Vaccination rates were higher in psoriasis patients aged over 50 years, those who were female, and those with other chronic medical conditions, however.

Megan H. Noe, MD, of the department of dermatology at the University of Pennsylvania, Philadelphia, and her coauthors referred to recent evidence suggesting that psoriasis involves systemic inflammation that increase the risk of comorbidities and that hospitalization rates for serious infections, including lower respiratory tract infections and pneumonia, are higher among adults with psoriasis than those who do not have psoriasis.

To compare influenza vaccination rates in psoriasis patients with those among patients with other chronic diseases, they conducted a cohort study, drawing from administrative and commercial claims data from OptumInsight Clinformatics Data Mart. They examined all adult patients with psoriasis, RA, or chronic hypertension who required oral antihypertensive medication. The study population included individuals tracked during the 2010-2011 flu season and 24 months prior (September 2008 to March 2011). This year was chosen because it was labeled as a “typical” season by the Centers for Disease Control and Prevention.

The primary outcome was a claim for an influenza vaccine, and covariates included age, length of residency, gender, and a clinical history of a range of conditions known to be associated with greater risk of influenza complications.

The population included 17,078 patients with psoriasis, 21,832 with RA, and 496,972 with chronic hypertension. After controlling for sex and age, the probability of getting a flu vaccine was similar between psoriasis and hypertension patients, but RA patients were more likely to be vaccinated than patients with psoriasis (odds ratio, 1.08; 95% confidence interval, 1.03-1.13). But the likelihood varied with age: 30-year-old patients with RA were more likely than a 30-year-old psoriasis patient to get a flu shot (OR, 1.30; 95% CI, 1.18-1.45), while a 70-year-old patient with RA was about as likely to get the flu vaccine as a 70-year-old patient with psoriasis.

Female psoriasis patients were more likely to get a flu shot than males (OR, 1.29; 95% CI, 1.20-1.38). Among the psoriasis patients, having some medical comorbidities were linked to a greater likelihood of being vaccinated, including asthma (OR, 1.58; 95% CI, 1.40-1.77), chronic liver disease (OR, 1.23; 95%, 1.03-1.47), diabetes (OR, 1.48; 95% CI, 1.36-1.63), HIV (OR, 3.68; 95% CI, 2.06-6.57), history of malignancy (OR, 1.21; 95% CI, 1.09-1.34), and psoriatic arthritis (OR, 1.40; 95% CI, 1.25-1.58).

There was no association between the use of an oral systemic therapy or biologic treatment and vaccination rates.

The authors suggested that psoriasis patients, especially younger ones, may not get adequate counseling on the value of the flu vaccine from their physicians. Studies have shown that, among the American public, health care providers are the most influential source of information about the flu vaccine. Among younger patients, the dermatologist may be a psoriasis patient’s primary health care provider, so it is important for dermatologists to counsel patients about the recommended vaccines, the authors wrote.

“Further research understanding why adults with psoriasis do not receive recommended vaccinations will help to create targeted interventions to improve vaccination rates and decrease hospitalizations in adults with psoriasis,” they concluded.

The study relied on administrative claims, so the results may not be generalizable to patients with insurance types other than those in the database or who are uninsured, the authors noted.

This study was funded by the National Psoriasis Foundation, the Dermatology Foundation, and the National Institute of Arthritis and Musculoskeletal and Skin Diseases. Dr. Noe and three other authors did not report any disclosures, the fifth author reported multiple disclosures related to various pharmaceutical companies.

SOURCE: Noe MH et al. J Invest Dermatol. 2018 Oct 10. doi: 10.1016/j.jid.2018.09.012.
 

Psoriasis patients are more vulnerable to systemic infections, including influenza-related pneumonia, but a new study shows that they are less likely to receive the influenza vaccine than patients with RA.

Jovanmandic/Thinkstock

Vaccination rates were higher in psoriasis patients aged over 50 years, those who were female, and those with other chronic medical conditions, however.

Megan H. Noe, MD, of the department of dermatology at the University of Pennsylvania, Philadelphia, and her coauthors referred to recent evidence suggesting that psoriasis involves systemic inflammation that increase the risk of comorbidities and that hospitalization rates for serious infections, including lower respiratory tract infections and pneumonia, are higher among adults with psoriasis than those who do not have psoriasis.

To compare influenza vaccination rates in psoriasis patients with those among patients with other chronic diseases, they conducted a cohort study, drawing from administrative and commercial claims data from OptumInsight Clinformatics Data Mart. They examined all adult patients with psoriasis, RA, or chronic hypertension who required oral antihypertensive medication. The study population included individuals tracked during the 2010-2011 flu season and 24 months prior (September 2008 to March 2011). This year was chosen because it was labeled as a “typical” season by the Centers for Disease Control and Prevention.

The primary outcome was a claim for an influenza vaccine, and covariates included age, length of residency, gender, and a clinical history of a range of conditions known to be associated with greater risk of influenza complications.

The population included 17,078 patients with psoriasis, 21,832 with RA, and 496,972 with chronic hypertension. After controlling for sex and age, the probability of getting a flu vaccine was similar between psoriasis and hypertension patients, but RA patients were more likely to be vaccinated than patients with psoriasis (odds ratio, 1.08; 95% confidence interval, 1.03-1.13). But the likelihood varied with age: 30-year-old patients with RA were more likely than a 30-year-old psoriasis patient to get a flu shot (OR, 1.30; 95% CI, 1.18-1.45), while a 70-year-old patient with RA was about as likely to get the flu vaccine as a 70-year-old patient with psoriasis.

Female psoriasis patients were more likely to get a flu shot than males (OR, 1.29; 95% CI, 1.20-1.38). Among the psoriasis patients, having some medical comorbidities were linked to a greater likelihood of being vaccinated, including asthma (OR, 1.58; 95% CI, 1.40-1.77), chronic liver disease (OR, 1.23; 95%, 1.03-1.47), diabetes (OR, 1.48; 95% CI, 1.36-1.63), HIV (OR, 3.68; 95% CI, 2.06-6.57), history of malignancy (OR, 1.21; 95% CI, 1.09-1.34), and psoriatic arthritis (OR, 1.40; 95% CI, 1.25-1.58).

There was no association between the use of an oral systemic therapy or biologic treatment and vaccination rates.

The authors suggested that psoriasis patients, especially younger ones, may not get adequate counseling on the value of the flu vaccine from their physicians. Studies have shown that, among the American public, health care providers are the most influential source of information about the flu vaccine. Among younger patients, the dermatologist may be a psoriasis patient’s primary health care provider, so it is important for dermatologists to counsel patients about the recommended vaccines, the authors wrote.

“Further research understanding why adults with psoriasis do not receive recommended vaccinations will help to create targeted interventions to improve vaccination rates and decrease hospitalizations in adults with psoriasis,” they concluded.

The study relied on administrative claims, so the results may not be generalizable to patients with insurance types other than those in the database or who are uninsured, the authors noted.

This study was funded by the National Psoriasis Foundation, the Dermatology Foundation, and the National Institute of Arthritis and Musculoskeletal and Skin Diseases. Dr. Noe and three other authors did not report any disclosures, the fifth author reported multiple disclosures related to various pharmaceutical companies.

SOURCE: Noe MH et al. J Invest Dermatol. 2018 Oct 10. doi: 10.1016/j.jid.2018.09.012.
 

CHICAGO – A common reason why a women stops breastfeeding is the use of medication her doctor has claimed is unsafe during lactation. But most drugs have little or no effect on an infant’s well-being or milk supply, explained Jenny Eileen Murase, MD, of Palo Alto (Calif.) Foundation Medical Group.

“The bottom line I want you to take away from this [session] is that the vast majority of the medicines you are prescribing as a dermatologist are safe during lactation,” Dr. Murase told attendees at the American Academy of Dermatology summer meeting. “I really want everyone in this room to understand that most of the time, you should not be recommending that a woman is pumping and dumping her milk or stopping breastfeeding because she’s on an agent.”

Dr. Murase, also affiliated with the University of California, San Francisco, provided an overview of drug safety during lactation for major categories of medications that dermatologists prescribe. She recommended that physicians get a copy of Medications and Mother’s Milk by Thomas Hale, PhD, which she considers the best reference for looking up specific drugs. It categorizes drugs as L1 (safest) to L5 (contraindicated), and L2 as “safer,” L3 as “moderately safe,” and L4 as “possibly hazardous.”

Steroids

Contrary to what many believe, prednisone is not contraindicated in breastfeeding, Dr. Murase said. Instead of advising patients to “pump and dump their milk,” she said, “the only recommendation you need to make is that they wait 4 hours after taking the medicine to breastfeed.” For example, a mother can take prednisone before bed and then wake 4 hours later to nurse. Higher doses, such as more than 40 mg daily over long periods, may have the potential to affect growth and development, but more typical doses don’t pose the same risk.

Topical steroids (except for those that are class 1) also are safe to apply directly to the nipple in breastfeeding women, she noted.

Biologics and immunosuppressants

One of the few medications that are contraindicated are topical pimecrolimus and tacrolimus if applied directly to the nipple, since “oral consumption in the infant could be significant,” Dr. Murase said.

Biologics, on the other hand, are not a concern during lactation. “They have low oral bioavailability because of their large molecular size,” and are broken down in the stomach “in a proteolytic environment,” Dr. Murase explained. The CRADLE study, for example, examined the concentration of certolizumab (Cimzia) in mothers’ mature breast milk and found the highest concentration to be just 0.077 mcg/mL, resulting in an average daily infant dose of less than 0.01 mg/kg per day.

Antihistamines and cosmetic topicals

The major antihistamines – brompheniramine, chlorpheniramine, diphenhydramine, hydroxyzine, cetirizine, fexofenadine and loratadine – are likewise safe as L1-L3 drugs. It is preferable to prescribe nonsedating antihistamines, opting for loratadine as the first-line choice. But dermatologists should be reassured that no data support concerns about milk supply reduction from antihistamines, Dr. Murase said.

It’s best to avoid cosmetic topical products, but hydroquinone (L3), topical minoxidil (L2), and botulinum toxin A (L3) do not pose significant risk to the infant. Neither do the anesthetics lidocaine (L2) and epinephrine (L1) for breastfeeding women who need surgery.

Antibiotics

The vast majority of antibiotics are safe for women to use while breastfeeding, but a few notable exceptions exist, including erythromycin.

“People associate erythromycin as safe in lactation because it’s safe in pregnancy, but that’s not the case,” Dr. Murase pointed out. Erythromycin has been linked to pyloric stenosis in newborns and therefore should be avoided in the early months of breastfeeding. In older infants, however, erythromycin becomes an L1 medication.”

Tetracyclines fall into a borderline category. “Tetracyclines would be fine for a complicated infection,” but should not be used for more than 3 weeks, at which point they are regarded as L4, Dr. Murase said. “So long-term use of the tetracyclines should be avoided.”

Aside from these, topical antibiotics are considered safe. Women taking other oral antibiotics should be monitored for gastrointestinal symptoms or allergic responses.

Antifungals

As for antifungals, topicals are safe, and nystatin and clotrimazole are the best first-line options (both L1). Oral antifungals are similarly fine, with griseofulvin, fluconazole, ketoconazole, itraconazole, and terbinafine all classified as L2 and amphotericin B as L3.

If antifungals or antibiotics are being prescribed for a breast fungal infection or for mastitis, Dr. Murase underscored the importance of not stopping breastfeeding.

“The most important thing is that they continue to actually breastfeed on the affected breast that has the staph infection,” she said. She then reiterated that physicians should “reassure new mothers that the majority of oral and topical medications are safe.”

Dr. Murase disclosed serving on the advisory boards of Dermira, UCB, and Genzyme/Sanofi, and she has consulted for Ferndale and UpToDate.

CHICAGO – A common reason why a women stops breastfeeding is the use of medication her doctor has claimed is unsafe during lactation. But most drugs have little or no effect on an infant’s well-being or milk supply, explained Jenny Eileen Murase, MD, of Palo Alto (Calif.) Foundation Medical Group.

“The bottom line I want you to take away from this [session] is that the vast majority of the medicines you are prescribing as a dermatologist are safe during lactation,” Dr. Murase told attendees at the American Academy of Dermatology summer meeting. “I really want everyone in this room to understand that most of the time, you should not be recommending that a woman is pumping and dumping her milk or stopping breastfeeding because she’s on an agent.”

Dr. Murase, also affiliated with the University of California, San Francisco, provided an overview of drug safety during lactation for major categories of medications that dermatologists prescribe. She recommended that physicians get a copy of Medications and Mother’s Milk by Thomas Hale, PhD, which she considers the best reference for looking up specific drugs. It categorizes drugs as L1 (safest) to L5 (contraindicated), and L2 as “safer,” L3 as “moderately safe,” and L4 as “possibly hazardous.”

Steroids

Contrary to what many believe, prednisone is not contraindicated in breastfeeding, Dr. Murase said. Instead of advising patients to “pump and dump their milk,” she said, “the only recommendation you need to make is that they wait 4 hours after taking the medicine to breastfeed.” For example, a mother can take prednisone before bed and then wake 4 hours later to nurse. Higher doses, such as more than 40 mg daily over long periods, may have the potential to affect growth and development, but more typical doses don’t pose the same risk.

Topical steroids (except for those that are class 1) also are safe to apply directly to the nipple in breastfeeding women, she noted.

Biologics and immunosuppressants

One of the few medications that are contraindicated are topical pimecrolimus and tacrolimus if applied directly to the nipple, since “oral consumption in the infant could be significant,” Dr. Murase said.

Biologics, on the other hand, are not a concern during lactation. “They have low oral bioavailability because of their large molecular size,” and are broken down in the stomach “in a proteolytic environment,” Dr. Murase explained. The CRADLE study, for example, examined the concentration of certolizumab (Cimzia) in mothers’ mature breast milk and found the highest concentration to be just 0.077 mcg/mL, resulting in an average daily infant dose of less than 0.01 mg/kg per day.

Antihistamines and cosmetic topicals

The major antihistamines – brompheniramine, chlorpheniramine, diphenhydramine, hydroxyzine, cetirizine, fexofenadine and loratadine – are likewise safe as L1-L3 drugs. It is preferable to prescribe nonsedating antihistamines, opting for loratadine as the first-line choice. But dermatologists should be reassured that no data support concerns about milk supply reduction from antihistamines, Dr. Murase said.

It’s best to avoid cosmetic topical products, but hydroquinone (L3), topical minoxidil (L2), and botulinum toxin A (L3) do not pose significant risk to the infant. Neither do the anesthetics lidocaine (L2) and epinephrine (L1) for breastfeeding women who need surgery.

Antibiotics

The vast majority of antibiotics are safe for women to use while breastfeeding, but a few notable exceptions exist, including erythromycin.

“People associate erythromycin as safe in lactation because it’s safe in pregnancy, but that’s not the case,” Dr. Murase pointed out. Erythromycin has been linked to pyloric stenosis in newborns and therefore should be avoided in the early months of breastfeeding. In older infants, however, erythromycin becomes an L1 medication.”

Tetracyclines fall into a borderline category. “Tetracyclines would be fine for a complicated infection,” but should not be used for more than 3 weeks, at which point they are regarded as L4, Dr. Murase said. “So long-term use of the tetracyclines should be avoided.”

Aside from these, topical antibiotics are considered safe. Women taking other oral antibiotics should be monitored for gastrointestinal symptoms or allergic responses.

Antifungals

As for antifungals, topicals are safe, and nystatin and clotrimazole are the best first-line options (both L1). Oral antifungals are similarly fine, with griseofulvin, fluconazole, ketoconazole, itraconazole, and terbinafine all classified as L2 and amphotericin B as L3.

If antifungals or antibiotics are being prescribed for a breast fungal infection or for mastitis, Dr. Murase underscored the importance of not stopping breastfeeding.

“The most important thing is that they continue to actually breastfeed on the affected breast that has the staph infection,” she said. She then reiterated that physicians should “reassure new mothers that the majority of oral and topical medications are safe.”

Dr. Murase disclosed serving on the advisory boards of Dermira, UCB, and Genzyme/Sanofi, and she has consulted for Ferndale and UpToDate.

CHICAGO – A common reason why a women stops breastfeeding is the use of medication her doctor has claimed is unsafe during lactation. But most drugs have little or no effect on an infant’s well-being or milk supply, explained Jenny Eileen Murase, MD, of Palo Alto (Calif.) Foundation Medical Group.

“The bottom line I want you to take away from this [session] is that the vast majority of the medicines you are prescribing as a dermatologist are safe during lactation,” Dr. Murase told attendees at the American Academy of Dermatology summer meeting. “I really want everyone in this room to understand that most of the time, you should not be recommending that a woman is pumping and dumping her milk or stopping breastfeeding because she’s on an agent.”

Dr. Murase, also affiliated with the University of California, San Francisco, provided an overview of drug safety during lactation for major categories of medications that dermatologists prescribe. She recommended that physicians get a copy of Medications and Mother’s Milk by Thomas Hale, PhD, which she considers the best reference for looking up specific drugs. It categorizes drugs as L1 (safest) to L5 (contraindicated), and L2 as “safer,” L3 as “moderately safe,” and L4 as “possibly hazardous.”

Steroids

Contrary to what many believe, prednisone is not contraindicated in breastfeeding, Dr. Murase said. Instead of advising patients to “pump and dump their milk,” she said, “the only recommendation you need to make is that they wait 4 hours after taking the medicine to breastfeed.” For example, a mother can take prednisone before bed and then wake 4 hours later to nurse. Higher doses, such as more than 40 mg daily over long periods, may have the potential to affect growth and development, but more typical doses don’t pose the same risk.

Topical steroids (except for those that are class 1) also are safe to apply directly to the nipple in breastfeeding women, she noted.

Biologics and immunosuppressants

One of the few medications that are contraindicated are topical pimecrolimus and tacrolimus if applied directly to the nipple, since “oral consumption in the infant could be significant,” Dr. Murase said.

Biologics, on the other hand, are not a concern during lactation. “They have low oral bioavailability because of their large molecular size,” and are broken down in the stomach “in a proteolytic environment,” Dr. Murase explained. The CRADLE study, for example, examined the concentration of certolizumab (Cimzia) in mothers’ mature breast milk and found the highest concentration to be just 0.077 mcg/mL, resulting in an average daily infant dose of less than 0.01 mg/kg per day.

Antihistamines and cosmetic topicals

The major antihistamines – brompheniramine, chlorpheniramine, diphenhydramine, hydroxyzine, cetirizine, fexofenadine and loratadine – are likewise safe as L1-L3 drugs. It is preferable to prescribe nonsedating antihistamines, opting for loratadine as the first-line choice. But dermatologists should be reassured that no data support concerns about milk supply reduction from antihistamines, Dr. Murase said.

It’s best to avoid cosmetic topical products, but hydroquinone (L3), topical minoxidil (L2), and botulinum toxin A (L3) do not pose significant risk to the infant. Neither do the anesthetics lidocaine (L2) and epinephrine (L1) for breastfeeding women who need surgery.

Antibiotics

The vast majority of antibiotics are safe for women to use while breastfeeding, but a few notable exceptions exist, including erythromycin.

“People associate erythromycin as safe in lactation because it’s safe in pregnancy, but that’s not the case,” Dr. Murase pointed out. Erythromycin has been linked to pyloric stenosis in newborns and therefore should be avoided in the early months of breastfeeding. In older infants, however, erythromycin becomes an L1 medication.”

Tetracyclines fall into a borderline category. “Tetracyclines would be fine for a complicated infection,” but should not be used for more than 3 weeks, at which point they are regarded as L4, Dr. Murase said. “So long-term use of the tetracyclines should be avoided.”

Aside from these, topical antibiotics are considered safe. Women taking other oral antibiotics should be monitored for gastrointestinal symptoms or allergic responses.

Antifungals

As for antifungals, topicals are safe, and nystatin and clotrimazole are the best first-line options (both L1). Oral antifungals are similarly fine, with griseofulvin, fluconazole, ketoconazole, itraconazole, and terbinafine all classified as L2 and amphotericin B as L3.

If antifungals or antibiotics are being prescribed for a breast fungal infection or for mastitis, Dr. Murase underscored the importance of not stopping breastfeeding.

“The most important thing is that they continue to actually breastfeed on the affected breast that has the staph infection,” she said. She then reiterated that physicians should “reassure new mothers that the majority of oral and topical medications are safe.”

Dr. Murase disclosed serving on the advisory boards of Dermira, UCB, and Genzyme/Sanofi, and she has consulted for Ferndale and UpToDate.

Psoriasis patients have many options, and more are on the way, according to J. Mark Jackson, MD, of the University of Louisville, Ky.

“Know the information regarding each [treatment] to best care for your patients,” Dr. Jackson said in a presentation at the annual Coastal Dermatology Symposium.

Dr. Jackson particularly addressed the interleukin (IL)-17 inhibitors (brodalumab, ixekizumab, and secukinumab) and the IL-23 inhibitors (guselkumab, risankizumab, and tildrakizumab).

Complete clearance rates can reach 50% and higher over the long term when treating patients with IL-17 inhibitors, but patients must maintain regular dosing to maintain a response, he said.

Overall, comparisons of IL-17 inhibitors with etanercept, adalimumab, and ustekinumab “demonstrate better efficacy with no evidence of compromising safety,” he noted.

For example, secukinumab demonstrated significantly superior results when compared with ustekinumab in a randomized trial (J Am Acad Dermatol. 2015;73: 400-9). After 16 weeks of treatment, 79% of secukinumab patients achieved a 90% reduction in Psoriasis Area and Severity Index score (PASI 90) versus 58% of ustekinumab patients, he said, and the drug safety profile was consistent with the pivotal phase 3 studies of secukinumab.

Concerns persist about increased risk of inflammatory bowel disease, Crohn’s disease, and ulcerative colitis in patients taking secukinumab and other IL-17 inhibitors, but data indicate that rates are low. The risk is low “and may be related to psoriasis and not the therapy,” he explained.

Ixekizumab has been associated with more injection site reactions than secukinumab, but these tend to be mild, Dr. Jackson said. Advantages of ixekizumab are that it works quickly and has demonstrated effectiveness against genital, palmoplantar, scalp, and nail psoriasis, he added.

Brodalumab also works quickly, but it has the unique inclusion of a Risk Evaluation and Mitigation Strategies (REMS) program because of suicidal ideation and behavior in clinical trials, he noted, adding that there are more data showing rates are low and the REMS program is easier to deal with than the isotretinoin REMS. The increased risk of superficial Staphylococcus and Candida infections are noted on IL-17 inhibitor labels, but this has not been a significant issue in trials or clinical practice, he said.

What is also exciting about the IL-17 inhibitors are the approvals of ixekizumab and secukinumab for patients with psoriatic arthritis (PsA), with both agents demonstrating the ability to inhibit the structural progression of joint damage over time, Dr. Jackson commented. These data seem to be on par with that of the TNF-inhibitors, although time will tell how this bears out clinically, he noted.

IL-23 inhibitors guselkumab, tildrakizumab, and risankizumab (not yet approved) have shown similar effectiveness and are well tolerated by patients, with few injection site reactions or adverse events reported, Dr. Jackson said. The dosing regimens of each of these drugs, administered subcutaneously, are easy to follow: Treatment starts with an initial dose of either 100 mg (guselkumab and tildrakizumab) or 150 mg (risankizumab), which is followed by doses at 4 weeks and then doses every 8 weeks (guselkumab) or 12 weeks (tildrakizumab and risankizumab).

For example, in a comparison study of risankizumab with a dosage of 150 mg subcutaneously at week 0, 4, then every 12 weeks, 75% of risankizumab patients achieved PASI 90 at 16 weeks and 82% at 52 weeks, compared with 42% and 44%, respectively, for adalimumab patients.

In addition, the IL-23 inhibitors have demonstrated some benefits for PsA patients in clinical trials, but they are not currently indicated for PsA, he said.

Dr. Jackson disclosed having received research, honoraria, consulting, and/or other support from AbbVie, Accuitis, Aclaris, Celgene, Dr. Reddy’s, Galderma, Janssen, Lilly, Medimetriks, Novartis, Pfizer, Promius, Ralexar, Sienna, and TopMD.

The meeting is jointly presented by the University of Louisville and Global Academy for Medical Education. This publication and Global Academy for Medical Education are both owned by Frontline Medical Communications.

Psoriasis patients have many options, and more are on the way, according to J. Mark Jackson, MD, of the University of Louisville, Ky.

“Know the information regarding each [treatment] to best care for your patients,” Dr. Jackson said in a presentation at the annual Coastal Dermatology Symposium.

Dr. Jackson particularly addressed the interleukin (IL)-17 inhibitors (brodalumab, ixekizumab, and secukinumab) and the IL-23 inhibitors (guselkumab, risankizumab, and tildrakizumab).

Complete clearance rates can reach 50% and higher over the long term when treating patients with IL-17 inhibitors, but patients must maintain regular dosing to maintain a response, he said.

Overall, comparisons of IL-17 inhibitors with etanercept, adalimumab, and ustekinumab “demonstrate better efficacy with no evidence of compromising safety,” he noted.

For example, secukinumab demonstrated significantly superior results when compared with ustekinumab in a randomized trial (J Am Acad Dermatol. 2015;73: 400-9). After 16 weeks of treatment, 79% of secukinumab patients achieved a 90% reduction in Psoriasis Area and Severity Index score (PASI 90) versus 58% of ustekinumab patients, he said, and the drug safety profile was consistent with the pivotal phase 3 studies of secukinumab.

Concerns persist about increased risk of inflammatory bowel disease, Crohn’s disease, and ulcerative colitis in patients taking secukinumab and other IL-17 inhibitors, but data indicate that rates are low. The risk is low “and may be related to psoriasis and not the therapy,” he explained.

Ixekizumab has been associated with more injection site reactions than secukinumab, but these tend to be mild, Dr. Jackson said. Advantages of ixekizumab are that it works quickly and has demonstrated effectiveness against genital, palmoplantar, scalp, and nail psoriasis, he added.

Brodalumab also works quickly, but it has the unique inclusion of a Risk Evaluation and Mitigation Strategies (REMS) program because of suicidal ideation and behavior in clinical trials, he noted, adding that there are more data showing rates are low and the REMS program is easier to deal with than the isotretinoin REMS. The increased risk of superficial Staphylococcus and Candida infections are noted on IL-17 inhibitor labels, but this has not been a significant issue in trials or clinical practice, he said.

What is also exciting about the IL-17 inhibitors are the approvals of ixekizumab and secukinumab for patients with psoriatic arthritis (PsA), with both agents demonstrating the ability to inhibit the structural progression of joint damage over time, Dr. Jackson commented. These data seem to be on par with that of the TNF-inhibitors, although time will tell how this bears out clinically, he noted.

IL-23 inhibitors guselkumab, tildrakizumab, and risankizumab (not yet approved) have shown similar effectiveness and are well tolerated by patients, with few injection site reactions or adverse events reported, Dr. Jackson said. The dosing regimens of each of these drugs, administered subcutaneously, are easy to follow: Treatment starts with an initial dose of either 100 mg (guselkumab and tildrakizumab) or 150 mg (risankizumab), which is followed by doses at 4 weeks and then doses every 8 weeks (guselkumab) or 12 weeks (tildrakizumab and risankizumab).

For example, in a comparison study of risankizumab with a dosage of 150 mg subcutaneously at week 0, 4, then every 12 weeks, 75% of risankizumab patients achieved PASI 90 at 16 weeks and 82% at 52 weeks, compared with 42% and 44%, respectively, for adalimumab patients.

In addition, the IL-23 inhibitors have demonstrated some benefits for PsA patients in clinical trials, but they are not currently indicated for PsA, he said.

Dr. Jackson disclosed having received research, honoraria, consulting, and/or other support from AbbVie, Accuitis, Aclaris, Celgene, Dr. Reddy’s, Galderma, Janssen, Lilly, Medimetriks, Novartis, Pfizer, Promius, Ralexar, Sienna, and TopMD.

The meeting is jointly presented by the University of Louisville and Global Academy for Medical Education. This publication and Global Academy for Medical Education are both owned by Frontline Medical Communications.

Psoriasis patients have many options, and more are on the way, according to J. Mark Jackson, MD, of the University of Louisville, Ky.

“Know the information regarding each [treatment] to best care for your patients,” Dr. Jackson said in a presentation at the annual Coastal Dermatology Symposium.

Dr. Jackson particularly addressed the interleukin (IL)-17 inhibitors (brodalumab, ixekizumab, and secukinumab) and the IL-23 inhibitors (guselkumab, risankizumab, and tildrakizumab).

Complete clearance rates can reach 50% and higher over the long term when treating patients with IL-17 inhibitors, but patients must maintain regular dosing to maintain a response, he said.

Overall, comparisons of IL-17 inhibitors with etanercept, adalimumab, and ustekinumab “demonstrate better efficacy with no evidence of compromising safety,” he noted.

For example, secukinumab demonstrated significantly superior results when compared with ustekinumab in a randomized trial (J Am Acad Dermatol. 2015;73: 400-9). After 16 weeks of treatment, 79% of secukinumab patients achieved a 90% reduction in Psoriasis Area and Severity Index score (PASI 90) versus 58% of ustekinumab patients, he said, and the drug safety profile was consistent with the pivotal phase 3 studies of secukinumab.

Concerns persist about increased risk of inflammatory bowel disease, Crohn’s disease, and ulcerative colitis in patients taking secukinumab and other IL-17 inhibitors, but data indicate that rates are low. The risk is low “and may be related to psoriasis and not the therapy,” he explained.

Ixekizumab has been associated with more injection site reactions than secukinumab, but these tend to be mild, Dr. Jackson said. Advantages of ixekizumab are that it works quickly and has demonstrated effectiveness against genital, palmoplantar, scalp, and nail psoriasis, he added.

Brodalumab also works quickly, but it has the unique inclusion of a Risk Evaluation and Mitigation Strategies (REMS) program because of suicidal ideation and behavior in clinical trials, he noted, adding that there are more data showing rates are low and the REMS program is easier to deal with than the isotretinoin REMS. The increased risk of superficial Staphylococcus and Candida infections are noted on IL-17 inhibitor labels, but this has not been a significant issue in trials or clinical practice, he said.

What is also exciting about the IL-17 inhibitors are the approvals of ixekizumab and secukinumab for patients with psoriatic arthritis (PsA), with both agents demonstrating the ability to inhibit the structural progression of joint damage over time, Dr. Jackson commented. These data seem to be on par with that of the TNF-inhibitors, although time will tell how this bears out clinically, he noted.

IL-23 inhibitors guselkumab, tildrakizumab, and risankizumab (not yet approved) have shown similar effectiveness and are well tolerated by patients, with few injection site reactions or adverse events reported, Dr. Jackson said. The dosing regimens of each of these drugs, administered subcutaneously, are easy to follow: Treatment starts with an initial dose of either 100 mg (guselkumab and tildrakizumab) or 150 mg (risankizumab), which is followed by doses at 4 weeks and then doses every 8 weeks (guselkumab) or 12 weeks (tildrakizumab and risankizumab).

For example, in a comparison study of risankizumab with a dosage of 150 mg subcutaneously at week 0, 4, then every 12 weeks, 75% of risankizumab patients achieved PASI 90 at 16 weeks and 82% at 52 weeks, compared with 42% and 44%, respectively, for adalimumab patients.

In addition, the IL-23 inhibitors have demonstrated some benefits for PsA patients in clinical trials, but they are not currently indicated for PsA, he said.

Dr. Jackson disclosed having received research, honoraria, consulting, and/or other support from AbbVie, Accuitis, Aclaris, Celgene, Dr. Reddy’s, Galderma, Janssen, Lilly, Medimetriks, Novartis, Pfizer, Promius, Ralexar, Sienna, and TopMD.

The meeting is jointly presented by the University of Louisville and Global Academy for Medical Education. This publication and Global Academy for Medical Education are both owned by Frontline Medical Communications.

Researchers have compiled a new long-term integrated analysis of safety data for adalimumab (Humira) that includes 5 clinical trials not included in the previous 2009 analysis; their evaluation of data from these 18 trials found no new safety signals, they reported in the British Journal of Dermatology.

Adverse event incidence rates were expressed as events per 100 patient-years of exposure to adalimumab and, among the 3,727 patients who were aged 18 years or older and had moderate to severe plaque psoriasis for at least 6 months, there were 5,430 patient-years of cumulative exposure at the December 2015 cutoff date.

There were 3,798 treatment-related events altogether (70 events/100 patient-years); 269 events (5 events/100 patient-years ) led to discontinuation of treatment. The rates for serious adverse events and serious infections were 8.4 and 1.8 events per 100 patient-years, respectively; the most common types of serious infections were pneumonia and cellulitis.

The rates of the most frequently reported adverse events were comparable with those in the 2009 data set, with the most common being nasopharyngitis, upper respiratory tract infection, and headache. Furthermore, the rates of serious adverse events, serious infections, and malignancies were also stable, even with the increasing adalimumab exposure, and these were mostly consistent with what has been seen in large real-world registries.

The researchers did note that the rates of melanoma and nonmelanoma skin cancer were higher than would be expected in the general population, but they suspected this was at least partly because these psoriasis patients were receiving more frequent skin examinations and more skin cancers were being detected. (Incidence rates for these two cancers were stable during 2009-2015).

The analysis had certain limitations, such as a lack of a long-term comparator group. Also, while some patients continue to receive adalimumab for more than 10 years, the maximum duration of treatment in this analysis was only 5.5 years. Finally, the population in these clinical trials may differ from that seen in general practice settings because of the inclusion/exclusion criteria.

Six authors of the study reported multiple disclosures with pharmaceutical companies, including serving as a consultant, speaker, and/or adviser for, receiving honoraria from, and/or receiving grant/research support from AbbVie, which developed adalimumab and funded/advised this study; two authors are AbbVie employees, one is a former employee.

cpalmer@mdedge.com

SOURCE: Leonardi C et al. Br J Dermatol. 2018 Aug 31. doi: 10.1111/bjd.17084.

Researchers have compiled a new long-term integrated analysis of safety data for adalimumab (Humira) that includes 5 clinical trials not included in the previous 2009 analysis; their evaluation of data from these 18 trials found no new safety signals, they reported in the British Journal of Dermatology.

Adverse event incidence rates were expressed as events per 100 patient-years of exposure to adalimumab and, among the 3,727 patients who were aged 18 years or older and had moderate to severe plaque psoriasis for at least 6 months, there were 5,430 patient-years of cumulative exposure at the December 2015 cutoff date.

There were 3,798 treatment-related events altogether (70 events/100 patient-years); 269 events (5 events/100 patient-years ) led to discontinuation of treatment. The rates for serious adverse events and serious infections were 8.4 and 1.8 events per 100 patient-years, respectively; the most common types of serious infections were pneumonia and cellulitis.

The rates of the most frequently reported adverse events were comparable with those in the 2009 data set, with the most common being nasopharyngitis, upper respiratory tract infection, and headache. Furthermore, the rates of serious adverse events, serious infections, and malignancies were also stable, even with the increasing adalimumab exposure, and these were mostly consistent with what has been seen in large real-world registries.

The researchers did note that the rates of melanoma and nonmelanoma skin cancer were higher than would be expected in the general population, but they suspected this was at least partly because these psoriasis patients were receiving more frequent skin examinations and more skin cancers were being detected. (Incidence rates for these two cancers were stable during 2009-2015).

The analysis had certain limitations, such as a lack of a long-term comparator group. Also, while some patients continue to receive adalimumab for more than 10 years, the maximum duration of treatment in this analysis was only 5.5 years. Finally, the population in these clinical trials may differ from that seen in general practice settings because of the inclusion/exclusion criteria.

Six authors of the study reported multiple disclosures with pharmaceutical companies, including serving as a consultant, speaker, and/or adviser for, receiving honoraria from, and/or receiving grant/research support from AbbVie, which developed adalimumab and funded/advised this study; two authors are AbbVie employees, one is a former employee.

cpalmer@mdedge.com

SOURCE: Leonardi C et al. Br J Dermatol. 2018 Aug 31. doi: 10.1111/bjd.17084.

Researchers have compiled a new long-term integrated analysis of safety data for adalimumab (Humira) that includes 5 clinical trials not included in the previous 2009 analysis; their evaluation of data from these 18 trials found no new safety signals, they reported in the British Journal of Dermatology.

Adverse event incidence rates were expressed as events per 100 patient-years of exposure to adalimumab and, among the 3,727 patients who were aged 18 years or older and had moderate to severe plaque psoriasis for at least 6 months, there were 5,430 patient-years of cumulative exposure at the December 2015 cutoff date.

There were 3,798 treatment-related events altogether (70 events/100 patient-years); 269 events (5 events/100 patient-years ) led to discontinuation of treatment. The rates for serious adverse events and serious infections were 8.4 and 1.8 events per 100 patient-years, respectively; the most common types of serious infections were pneumonia and cellulitis.

The rates of the most frequently reported adverse events were comparable with those in the 2009 data set, with the most common being nasopharyngitis, upper respiratory tract infection, and headache. Furthermore, the rates of serious adverse events, serious infections, and malignancies were also stable, even with the increasing adalimumab exposure, and these were mostly consistent with what has been seen in large real-world registries.

The researchers did note that the rates of melanoma and nonmelanoma skin cancer were higher than would be expected in the general population, but they suspected this was at least partly because these psoriasis patients were receiving more frequent skin examinations and more skin cancers were being detected. (Incidence rates for these two cancers were stable during 2009-2015).

The analysis had certain limitations, such as a lack of a long-term comparator group. Also, while some patients continue to receive adalimumab for more than 10 years, the maximum duration of treatment in this analysis was only 5.5 years. Finally, the population in these clinical trials may differ from that seen in general practice settings because of the inclusion/exclusion criteria.

Six authors of the study reported multiple disclosures with pharmaceutical companies, including serving as a consultant, speaker, and/or adviser for, receiving honoraria from, and/or receiving grant/research support from AbbVie, which developed adalimumab and funded/advised this study; two authors are AbbVie employees, one is a former employee.

cpalmer@mdedge.com

SOURCE: Leonardi C et al. Br J Dermatol. 2018 Aug 31. doi: 10.1111/bjd.17084.

CHICAGO – Psoriasis generally improves in most patients during pregnancy, but a subset of severe cases still occur that only systemic treatment can address, according to Kenneth B. Gordon, MD, professor and chair of dermatology at Medical College of Wisconsin in Milwaukee.

“We always had this concept that psoriasis gets better during pregnancy, that you might have 20% or 30% of patients who might have a little bit of a flare or maintain, but most keep on getting better,” Dr. Gordon told attendees at the American Academy of Dermatology summer meeting.

But the majority doesn’t mean everyone. He shared the case of one pregnant woman who came to him with severe psoriasis, covering the whole of her inner thigh, to underscore that severe cases do happen in pregnancy.

“These are real situations, and when you talk about maternal health, this woman is uncomfortable, she can’t sleep, and she’s having huge stressors that are not only going to impact her and her pregnancy but also that impact her child,” Dr. Gordon said.

Dr. Gordon clarified that he is not referring to patients with limited psoriasis or those who respond to topicals or phototherapy. But because methotrexate or acitretin are “hands-off during pregnancy,” he said, the only systemic therapy available for serious cases besides biologics is cyclosporine, which has its own risks. “We know that [cyclosporine] is associated with preterm labor and preterm birth and significant low birth weight, so even in the best scenario, when we have someone with persistent severe psoriasis in pregnancy, our best agent has a lot of downsides.”

Too few data exist on anti–interleukin (IL)-17 or anti-IL-23 therapies to draw conclusions about their use, he said, and but gastroenterology and rheumatology have a fair amount of evidence on anti–tumor necrosis factor (TNF) therapies during pregnancy because it’s usually too risky to stop treating conditions such as Crohn’s with these drugs. Still, Dr. Gordon cautioned, much of the data on biologics in pregnancy are conflicting.

The question of what medications to use, and in whom, centers on balancing risks to the fetus from the medication versus risks from the condition.

“There are impacts on the fetus of having severe psoriasis, and it varies with severity of disease,” Dr. Gordon said. For example, data suggest an increased likelihood of low birth weight in children born to mothers with severe psoriasis, and that risk may extend to preterm birth as well, although “we don’t know exactly the magnitude of that effect.”

Meanwhile, the consensus from the literature throughout dermatology, rheumatology, and gastroenterology is that anti-TNF agents do not cause birth defects or affect risk of preterm birth or low birth weight.

“The bigger question is what’s the impact on the immune system of the child,” Dr. Gordon said. Data from a small Scandinavian study suggested no increased risk of allergies, infections, or similar immunologic outcomes, but evidence remains limited.

Research has shown that infants’ exposure to anti-TNF medications persists for 3-6 months after delivery, and the American Academy of Pediatrics recommends delaying immunization in children exposed to anti-TNF agents in pregnancy. But actual evidence on immunization outcomes shows no reduced immunogenicity in such children.

“Clearly there is persistence of drug in the child, but in fact you have normal responses to immunization,” Dr. Gordon said. “The pediatricians’ argument is not based on data of what actually happens in immunization; it’s based on the fact that the drug is there.”

So what’s the bottom line?

The National Psoriasis Foundation recommends moisturizers and topical corticosteroids as first-line therapy in pregnant women with psoriasis, followed by phototherapy for second-line treatment.

But some patients will need systemic therapy during pregnancy, although it’s “best not to introduce more medications than needed in pregnancy,” Dr. Gordon said. For women with a significant flare-up or very persistent volatile disease, NPF first recommends cyclosporine, but Dr. Gordon disagrees and would go with anti-TNF agents before cyclosporine.

Data show that certolizumab is not actively transported across the placenta therefore reducing fetal exposure, so Dr. Gordon would specifically use certolizumab first, all other things being equal.

“But if the patient has been on another anti-TNF that’s been working, I don’t really have an issue with staying with it,” he added.

Existing evidence so far shows no impact in terms of genetic abnormalities, birth weight, premature birth, or even infant immunizations from anti-TNF agents. But beyond those, “there is simply not enough information on pregnancy with other forms of biologic therapy to draw conclusions.” Dr. Gordon said.

Dr. Gordon disclosed that he has received grant support and/or honoraria from Abbvie, Amgen, Almirall, and Boehringer Ingelheim.

CHICAGO – Psoriasis generally improves in most patients during pregnancy, but a subset of severe cases still occur that only systemic treatment can address, according to Kenneth B. Gordon, MD, professor and chair of dermatology at Medical College of Wisconsin in Milwaukee.

“We always had this concept that psoriasis gets better during pregnancy, that you might have 20% or 30% of patients who might have a little bit of a flare or maintain, but most keep on getting better,” Dr. Gordon told attendees at the American Academy of Dermatology summer meeting.

But the majority doesn’t mean everyone. He shared the case of one pregnant woman who came to him with severe psoriasis, covering the whole of her inner thigh, to underscore that severe cases do happen in pregnancy.

“These are real situations, and when you talk about maternal health, this woman is uncomfortable, she can’t sleep, and she’s having huge stressors that are not only going to impact her and her pregnancy but also that impact her child,” Dr. Gordon said.

Dr. Gordon clarified that he is not referring to patients with limited psoriasis or those who respond to topicals or phototherapy. But because methotrexate or acitretin are “hands-off during pregnancy,” he said, the only systemic therapy available for serious cases besides biologics is cyclosporine, which has its own risks. “We know that [cyclosporine] is associated with preterm labor and preterm birth and significant low birth weight, so even in the best scenario, when we have someone with persistent severe psoriasis in pregnancy, our best agent has a lot of downsides.”

Too few data exist on anti–interleukin (IL)-17 or anti-IL-23 therapies to draw conclusions about their use, he said, and but gastroenterology and rheumatology have a fair amount of evidence on anti–tumor necrosis factor (TNF) therapies during pregnancy because it’s usually too risky to stop treating conditions such as Crohn’s with these drugs. Still, Dr. Gordon cautioned, much of the data on biologics in pregnancy are conflicting.

The question of what medications to use, and in whom, centers on balancing risks to the fetus from the medication versus risks from the condition.

“There are impacts on the fetus of having severe psoriasis, and it varies with severity of disease,” Dr. Gordon said. For example, data suggest an increased likelihood of low birth weight in children born to mothers with severe psoriasis, and that risk may extend to preterm birth as well, although “we don’t know exactly the magnitude of that effect.”

Meanwhile, the consensus from the literature throughout dermatology, rheumatology, and gastroenterology is that anti-TNF agents do not cause birth defects or affect risk of preterm birth or low birth weight.

“The bigger question is what’s the impact on the immune system of the child,” Dr. Gordon said. Data from a small Scandinavian study suggested no increased risk of allergies, infections, or similar immunologic outcomes, but evidence remains limited.

Research has shown that infants’ exposure to anti-TNF medications persists for 3-6 months after delivery, and the American Academy of Pediatrics recommends delaying immunization in children exposed to anti-TNF agents in pregnancy. But actual evidence on immunization outcomes shows no reduced immunogenicity in such children.

“Clearly there is persistence of drug in the child, but in fact you have normal responses to immunization,” Dr. Gordon said. “The pediatricians’ argument is not based on data of what actually happens in immunization; it’s based on the fact that the drug is there.”

So what’s the bottom line?

The National Psoriasis Foundation recommends moisturizers and topical corticosteroids as first-line therapy in pregnant women with psoriasis, followed by phototherapy for second-line treatment.

But some patients will need systemic therapy during pregnancy, although it’s “best not to introduce more medications than needed in pregnancy,” Dr. Gordon said. For women with a significant flare-up or very persistent volatile disease, NPF first recommends cyclosporine, but Dr. Gordon disagrees and would go with anti-TNF agents before cyclosporine.

Data show that certolizumab is not actively transported across the placenta therefore reducing fetal exposure, so Dr. Gordon would specifically use certolizumab first, all other things being equal.

“But if the patient has been on another anti-TNF that’s been working, I don’t really have an issue with staying with it,” he added.

Existing evidence so far shows no impact in terms of genetic abnormalities, birth weight, premature birth, or even infant immunizations from anti-TNF agents. But beyond those, “there is simply not enough information on pregnancy with other forms of biologic therapy to draw conclusions.” Dr. Gordon said.

Dr. Gordon disclosed that he has received grant support and/or honoraria from Abbvie, Amgen, Almirall, and Boehringer Ingelheim.

CHICAGO – Psoriasis generally improves in most patients during pregnancy, but a subset of severe cases still occur that only systemic treatment can address, according to Kenneth B. Gordon, MD, professor and chair of dermatology at Medical College of Wisconsin in Milwaukee.

“We always had this concept that psoriasis gets better during pregnancy, that you might have 20% or 30% of patients who might have a little bit of a flare or maintain, but most keep on getting better,” Dr. Gordon told attendees at the American Academy of Dermatology summer meeting.

But the majority doesn’t mean everyone. He shared the case of one pregnant woman who came to him with severe psoriasis, covering the whole of her inner thigh, to underscore that severe cases do happen in pregnancy.

“These are real situations, and when you talk about maternal health, this woman is uncomfortable, she can’t sleep, and she’s having huge stressors that are not only going to impact her and her pregnancy but also that impact her child,” Dr. Gordon said.

Dr. Gordon clarified that he is not referring to patients with limited psoriasis or those who respond to topicals or phototherapy. But because methotrexate or acitretin are “hands-off during pregnancy,” he said, the only systemic therapy available for serious cases besides biologics is cyclosporine, which has its own risks. “We know that [cyclosporine] is associated with preterm labor and preterm birth and significant low birth weight, so even in the best scenario, when we have someone with persistent severe psoriasis in pregnancy, our best agent has a lot of downsides.”

Too few data exist on anti–interleukin (IL)-17 or anti-IL-23 therapies to draw conclusions about their use, he said, and but gastroenterology and rheumatology have a fair amount of evidence on anti–tumor necrosis factor (TNF) therapies during pregnancy because it’s usually too risky to stop treating conditions such as Crohn’s with these drugs. Still, Dr. Gordon cautioned, much of the data on biologics in pregnancy are conflicting.

The question of what medications to use, and in whom, centers on balancing risks to the fetus from the medication versus risks from the condition.

“There are impacts on the fetus of having severe psoriasis, and it varies with severity of disease,” Dr. Gordon said. For example, data suggest an increased likelihood of low birth weight in children born to mothers with severe psoriasis, and that risk may extend to preterm birth as well, although “we don’t know exactly the magnitude of that effect.”

Meanwhile, the consensus from the literature throughout dermatology, rheumatology, and gastroenterology is that anti-TNF agents do not cause birth defects or affect risk of preterm birth or low birth weight.

“The bigger question is what’s the impact on the immune system of the child,” Dr. Gordon said. Data from a small Scandinavian study suggested no increased risk of allergies, infections, or similar immunologic outcomes, but evidence remains limited.

Research has shown that infants’ exposure to anti-TNF medications persists for 3-6 months after delivery, and the American Academy of Pediatrics recommends delaying immunization in children exposed to anti-TNF agents in pregnancy. But actual evidence on immunization outcomes shows no reduced immunogenicity in such children.

“Clearly there is persistence of drug in the child, but in fact you have normal responses to immunization,” Dr. Gordon said. “The pediatricians’ argument is not based on data of what actually happens in immunization; it’s based on the fact that the drug is there.”

So what’s the bottom line?

The National Psoriasis Foundation recommends moisturizers and topical corticosteroids as first-line therapy in pregnant women with psoriasis, followed by phototherapy for second-line treatment.

But some patients will need systemic therapy during pregnancy, although it’s “best not to introduce more medications than needed in pregnancy,” Dr. Gordon said. For women with a significant flare-up or very persistent volatile disease, NPF first recommends cyclosporine, but Dr. Gordon disagrees and would go with anti-TNF agents before cyclosporine.

Data show that certolizumab is not actively transported across the placenta therefore reducing fetal exposure, so Dr. Gordon would specifically use certolizumab first, all other things being equal.

“But if the patient has been on another anti-TNF that’s been working, I don’t really have an issue with staying with it,” he added.

Existing evidence so far shows no impact in terms of genetic abnormalities, birth weight, premature birth, or even infant immunizations from anti-TNF agents. But beyond those, “there is simply not enough information on pregnancy with other forms of biologic therapy to draw conclusions.” Dr. Gordon said.

Dr. Gordon disclosed that he has received grant support and/or honoraria from Abbvie, Amgen, Almirall, and Boehringer Ingelheim.

The safety profile for adalimumab in children is similar to that of adults, according to findings published in the Journal of Pediatrics.

Lori Farmer/MDedge News

In an analysis of data from seven clinical trials from 2002-2015, the most common adverse events across indications were upper respiratory tract infection (24 events per 100 patient-years), nasopharyngitis (17 events per 100 PY), and headache (20 events per 100 PY). Serious infections were the most frequent adverse events across indications (8% of all patients; 4 events per 100 PY), reported Gerd Horneff, MD, of the department of general pediatrics at Asklepios Klinik Sankt Augustin (Germany), and his coauthors.

All of the clinical trials were funded by AbbVie, and included 577 pediatric patients with juvenile idiopathic arthritis (JIA), psoriasis, or Crohn’s disease. Patients received subcutaneous injection of adalimumab at a dosage of either 40 mg/0.8 mL or 20 mg/0.4 mL.

Adverse events that occurred after the first adalimumab dose and up to 70 days after the last dose were included. Serious adverse events were defined as “events that were fatal or immediately life-threatening; required inpatient or prolonged hospitalization; resulted in persistent or significant disability/incapacity, congenital anomaly, or spontaneous or elective abortion; or required medical or surgical intervention to prevent a serious outcome,” the authors said.

Infections occurred in 82% of JIA patients (151 events per 100 PY), 74% of patients with psoriasis (169 events per 100 PY), and 76% of patients with CD (132 events per 100 PY). The most common events for JIA, psoriasis, and Crohn’s were injection-site pain (22% of patients; 75 events per 100 PY), headache (30% of patients; 47 events per 100 PY), and worsening of Crohn’s disease (55% of patients; 37 events per 100 PY), respectively.

Serious adverse events occurred in 29% of patients. Rates for JIA, psoriasis, and Crohn’s were 14, 7, and 32 events per 100 PY, respectively. Serious infections were the most common serious adverse event, with rates of 3, 1, and 7 events per 100 PY for JIA, psoriasis, and Crohn’s disease, respectively. Pneumonia was the most commonly reported serious infection (1% of patients; 1 event per 100 PY). One death, due to an accidental fall, occurred in an adolescent patient with psoriasis.

The study findings add to “a more complete understanding of the established safety profile of adalimumab,” and suggest that in pediatric patients, “the overall safety profile was comparable and consistent with that in adults,” Dr. Horneff and his associates added.

AbbVie funded the study. Dr. Horneff has received grants from AbbVie, Chugai, Novartis, Pfizer, and Roche. Seven of the investigators are or were employees of AbbVie and may own AbbVie stock and stock options. Two of the investigators disclosed ties with a number of pharmaceutical companies.

SOURCE: Horneff G et al. J Pediatr. 2018 Oct. doi: 10.1016/j.jpeds.2018.05.042.

The safety profile for adalimumab in children is similar to that of adults, according to findings published in the Journal of Pediatrics.

Lori Farmer/MDedge News

In an analysis of data from seven clinical trials from 2002-2015, the most common adverse events across indications were upper respiratory tract infection (24 events per 100 patient-years), nasopharyngitis (17 events per 100 PY), and headache (20 events per 100 PY). Serious infections were the most frequent adverse events across indications (8% of all patients; 4 events per 100 PY), reported Gerd Horneff, MD, of the department of general pediatrics at Asklepios Klinik Sankt Augustin (Germany), and his coauthors.

All of the clinical trials were funded by AbbVie, and included 577 pediatric patients with juvenile idiopathic arthritis (JIA), psoriasis, or Crohn’s disease. Patients received subcutaneous injection of adalimumab at a dosage of either 40 mg/0.8 mL or 20 mg/0.4 mL.

Adverse events that occurred after the first adalimumab dose and up to 70 days after the last dose were included. Serious adverse events were defined as “events that were fatal or immediately life-threatening; required inpatient or prolonged hospitalization; resulted in persistent or significant disability/incapacity, congenital anomaly, or spontaneous or elective abortion; or required medical or surgical intervention to prevent a serious outcome,” the authors said.

Infections occurred in 82% of JIA patients (151 events per 100 PY), 74% of patients with psoriasis (169 events per 100 PY), and 76% of patients with CD (132 events per 100 PY). The most common events for JIA, psoriasis, and Crohn’s were injection-site pain (22% of patients; 75 events per 100 PY), headache (30% of patients; 47 events per 100 PY), and worsening of Crohn’s disease (55% of patients; 37 events per 100 PY), respectively.

Serious adverse events occurred in 29% of patients. Rates for JIA, psoriasis, and Crohn’s were 14, 7, and 32 events per 100 PY, respectively. Serious infections were the most common serious adverse event, with rates of 3, 1, and 7 events per 100 PY for JIA, psoriasis, and Crohn’s disease, respectively. Pneumonia was the most commonly reported serious infection (1% of patients; 1 event per 100 PY). One death, due to an accidental fall, occurred in an adolescent patient with psoriasis.

The study findings add to “a more complete understanding of the established safety profile of adalimumab,” and suggest that in pediatric patients, “the overall safety profile was comparable and consistent with that in adults,” Dr. Horneff and his associates added.

AbbVie funded the study. Dr. Horneff has received grants from AbbVie, Chugai, Novartis, Pfizer, and Roche. Seven of the investigators are or were employees of AbbVie and may own AbbVie stock and stock options. Two of the investigators disclosed ties with a number of pharmaceutical companies.

SOURCE: Horneff G et al. J Pediatr. 2018 Oct. doi: 10.1016/j.jpeds.2018.05.042.

The safety profile for adalimumab in children is similar to that of adults, according to findings published in the Journal of Pediatrics.

Lori Farmer/MDedge News

In an analysis of data from seven clinical trials from 2002-2015, the most common adverse events across indications were upper respiratory tract infection (24 events per 100 patient-years), nasopharyngitis (17 events per 100 PY), and headache (20 events per 100 PY). Serious infections were the most frequent adverse events across indications (8% of all patients; 4 events per 100 PY), reported Gerd Horneff, MD, of the department of general pediatrics at Asklepios Klinik Sankt Augustin (Germany), and his coauthors.

All of the clinical trials were funded by AbbVie, and included 577 pediatric patients with juvenile idiopathic arthritis (JIA), psoriasis, or Crohn’s disease. Patients received subcutaneous injection of adalimumab at a dosage of either 40 mg/0.8 mL or 20 mg/0.4 mL.

Adverse events that occurred after the first adalimumab dose and up to 70 days after the last dose were included. Serious adverse events were defined as “events that were fatal or immediately life-threatening; required inpatient or prolonged hospitalization; resulted in persistent or significant disability/incapacity, congenital anomaly, or spontaneous or elective abortion; or required medical or surgical intervention to prevent a serious outcome,” the authors said.

Infections occurred in 82% of JIA patients (151 events per 100 PY), 74% of patients with psoriasis (169 events per 100 PY), and 76% of patients with CD (132 events per 100 PY). The most common events for JIA, psoriasis, and Crohn’s were injection-site pain (22% of patients; 75 events per 100 PY), headache (30% of patients; 47 events per 100 PY), and worsening of Crohn’s disease (55% of patients; 37 events per 100 PY), respectively.

Serious adverse events occurred in 29% of patients. Rates for JIA, psoriasis, and Crohn’s were 14, 7, and 32 events per 100 PY, respectively. Serious infections were the most common serious adverse event, with rates of 3, 1, and 7 events per 100 PY for JIA, psoriasis, and Crohn’s disease, respectively. Pneumonia was the most commonly reported serious infection (1% of patients; 1 event per 100 PY). One death, due to an accidental fall, occurred in an adolescent patient with psoriasis.

The study findings add to “a more complete understanding of the established safety profile of adalimumab,” and suggest that in pediatric patients, “the overall safety profile was comparable and consistent with that in adults,” Dr. Horneff and his associates added.

AbbVie funded the study. Dr. Horneff has received grants from AbbVie, Chugai, Novartis, Pfizer, and Roche. Seven of the investigators are or were employees of AbbVie and may own AbbVie stock and stock options. Two of the investigators disclosed ties with a number of pharmaceutical companies.

SOURCE: Horneff G et al. J Pediatr. 2018 Oct. doi: 10.1016/j.jpeds.2018.05.042.