The Role of Etanercept on the Expression of Markers of T Helper 17 Cells and Their Precursors in Skin Lesions of Patients with Psoriasis Vulgaris

Abstract

Very recently, it has been demonstrated that CD161, retinoic acid—related orphan receptor γt (RORγt) and CC-chemokin receptor 6 (CCR6) can be considered good surface markers to detect T helper 17 cells and their precursors, T cell populations that are considered to play an important role in the pathogenesis of psoriasis. In the present study, we evaluate the clinical involvement by calculating the PASI score and the number of CD4+, CD161+, RORγt+ and CCR6+ cells before and after a 12-week course with etanercept or acitretin in patients with moderate-to-severe, plaque-type psoriasis vulgaris. Ten patients were given etanercept 50 mg twice weekly and 10 patients acitretin 0.4 mg/kg per day, both for 12 weeks. At the baseline and at the end of the treatment PASI was calculated, and skin biopsies were taken to evaluate the expression of CD4, CD161, RORyt and CCR6 by immunohistochemistry. As controls, 10 patients with atopic dermatitis (AD) were included in the study. After 12 weeks, PASI was significantly lower than at the baseline for both groups. However, etanercept-treated patients showed lower PASI than acitretin-treated ones. While CD4+ cell numbers were similar in both diseases, all the other markers, that are considered more specific for Th17 cells and their precursors, were more expressed in psoriasis than in AD. Furthermore, only etanercept, but not acitretin, was able to significantly reduce CD161+, RORγt+ and CCR6+ cells in skin lesions of patients with psoriasis. Our study provides further evidence of the role of Th17 pathway in the pathogenesis of psoriasis. Furthermore, our findings suggest that etanercept is able to downregulate the expression of the recently recognized markers of Th17 cells and their precursors CD161, RORγt and CCR6, while acitretin is not. This activity on the Th17 lineage may contribute to the efficacy of etanercept in the treatment of psoriasis.