Biological agents have dramatically improved treatment options for patients with severe psoriasis. Etanercept (tumor necrosis factor [TNF] receptor–immunoglobulin fusion protein) is an effective treatment for many psoriasis patients, and blockade of TNF is considered to be its primary action. However, in this clinical trial, we show that etanercept has early inhibitory effects on a newly appreciated type of T cells: T helper type 17 (Th17) cells. Etanercept reduced the inflammatory dendritic cell products that drive Th17 cell proliferation (interleukin [IL] 23), as well as Th17 cell products and downstream effector molecules (IL-17, IL-22, CC chemokine ligand 20, and β-defensin 4). In contrast, Th1 cellular products and effector molecules (interferon γ, lymphotoxin α, and myxovirus resistance 1) were reduced late in disease resolution. This study suggests a role for Th17 in addition to Th1 cells in the pathogenesis of psoriasis. Th17 cells may be particularly important in driving epidermal activation in psoriatic plaques, whereas Th1 cells must also be eliminated for final disease resolution.

We find that CD11c ؉ cells with many markers of dendritic cells (DCs) are a major cell type in the skin lesions of psoriasis. These CD11c ؉ cells, which are evident in both epidermis and dermis, are the sites for the expression of two mediators of inflammation, inducible nitric oxide synthase (iNOS) and TNF-␣ in diseased skin. These cells express HLA-DR, CD40, and CD86, lack the Langerin and CD14 markers of Langerhans cells and monocytes, respectively, and to a significant extent express the DC maturation markers DC-LAMP and CD83. Treatment of psoriasis with efalizumab (antiCD11a, Raptiva) strongly reduces infiltration by these DCs in patients responding to this agent. Disease activity after therapy was more related to DC infiltrates and iNOS mRNA levels than T cell infiltrates, and CD11c ؉ cells responded more quickly to therapy than epidermal keratinocytes. Our results suggest that a type of DC, which resembles murine ''Tip-DCs'' that can accumulate during infection, has proinflammatory effects in psoriasis through nitric oxide and TNF-␣ production, and can be an important target for suppressive therapies.autoimmune disease ͉ CD11c ͉ Tip-DC

Psoriasis is a hyperproliferative and inflammatory skin disorder of unknown aetiology. A fusion protein composed of human interleukin-2 and fragments of diphtheria toxin (DAB389IL-2), which selectively blocks the growth of activated lymphocytes but not keratinocytes, was administered systemically to ten patients to gauge the contribution of activated T cells to the disease. Four patients showed striking clinical improvement and four moderate improvement, after two cycle of low dose IL-2-toxin. The reversal of several molecular markers of epidermal dysfunction was associated with a marked reduction in intraepidermal CD3+ and CD8+ T cells, suggesting a primary immunological basis for this widespread disorder.

Background Atopic dermatitis (AD) is the most common inflammatory disease. Evolving disease models link changes in epidermal growth and differentiation to Th2/Th22 cytokine activation. However, these models have not been tested by in-vivo suppression of T-cell cytokines. CsA is an immune-suppressant highly effective for severe disease, but its mechanism in AD skin lesions has not been studied. Objective To establish the ability of a systemic immune-suppressant to modulate immune and epidermal alterations that form the pathogenic disease phenotype, and to correlate changes with clinical improvement. Methods CsA effects on AD skin pathology were evaluated using geneexpression and immunohistochemistry studies in baseline, week 2 and 12 lesional and non-lesional biopsies from 19 patients treated with 5 mg/kg/d CsA for 12 weeks. Results After 2 and 12 weeks of treatment, we observed significant reductions of 51% and 72%, respectively, in Scoring of AD/SCORAD. Clinical improvements were associated with significant gene expression changes in lesional but also non-lesional skin, particularly reductions of Th2-, Th22-, and some Th17-related molecules (i.e IL-13, IL-22, CCL17, S100As, elafin/PI3), and modulation of epidermal hyperplasia and differentiation measures. Conclusions This is the first study that establishes a relationship between cytokine activation and molecular epidermal alterations as well as correlations between disease biomarkers in the skin and clinical improvement. The reversal of the molecular phenotype with CsA and the associated biomarkers can serve as a reference for the successful modulation of tissue inflammation with specific immune-antagonists in future studies, contributing to the understanding of the specific cytokines involved in epidermal pathology.