T-helper (Th) 17 cell quantity and related cytokine expressions in skin lesions and peripheral blood of patients with psoriasis vulgaris

Abstract

Objective To detect the quantity of Th17 cells and expressions of related cytokines including interleukin (IL)-17 and IL-22, in peripheral blood and skin lesions of patients with psoriasis vulgaris, and to analyze their correlation with disease severity and clinical course. Methods Peripheral blood was obtained from 44 patients with progressive psoriasis vulgaris and 28 normal human controls. Three-color flow cytometry was carried out to detect the quantity of Th17 cells, and ELISA to examine the levels of serum IL-17 and -22.Skin samples were obtained from 20 patients with psoriasis vulgaris and 8 normal human controls, and a quantum dot-based double labled immumofluorescence method was used to determine the quantity of Th17 cells.Results The percentage of peripheral blood Th17 cells was higher in patients with psoriasis vulgaris than in normal human controls (4.71% ± 2.55% vs. 0.55% ± 0.39%, P ＜ 0.01 ). Elevated expressions of IL-17 and IL-22 were noted in the patients compared with the normal human controls (24.02 ± 12.31 ng/L vs. 7.16 ±4.04 ng/L, P ＜ 0.05; 18.32 ± 8.14 ng/L vs. 6.52 ± 4.15 ng/L, P ＜ 0.01 ). The percentage of peripheral blood Th17 cells and serum levels of IL-17 and IL-22 were positively correlated with psoriasis area and severity index (r= 0.53, 0.47, 0.53, respectively, all P ＜ 0.01 ), but unrelated to the clinical course of psoriasis (r = 0.09,0.03, 0.19, respectively, all P ＞ 0.05). There was an infiltrate of Th17 cells in psoriatic lesions, which was mainly distributed around the blood vessels in superficial dermis, whereas there were only a small number of CD4+ T cells in the normal control skin with the absence of Th17 cells. Conclusions Th17 cells are involved in the development of psoriasis, and Th17 cell-secreted cytokines, such as IL-17 and IL-22, may serve as a new therapeutic target for psoriasis. Key words: Psoriasis; CD4-positive T-lymphocytes; Interleukin-17; Interleukin-22