Analysis of blood follicular helper T cells in patients with psoriasis

Abstract

Psoriasis is a common, chronic inflammatory skin disease affecting about 2% of the worldwide population. Substantial clinical and basic research observations indicate that the cellular innate and adaptive immune responses, especially the activation of Th1 and Th17 cells, play a critical role in the pathogenesis of psoriasis. However, the role of B cells to pathogenesis of psoriasis is sparsely reported and controversial.Follicular helper T (Tfh) cell is a recently characterized subset of helper T cells, found in the germinal centers of the B cell follicles. The major function of Tfh cells is to help B cell activation and antibody production during humoral immune responses. Recently, several studies indicate that blood Tfh cells are frequently present in patients with autoimmune disease, such as systemic lupus erythematosus, rheumatoid arthritis and bullous pemphigoid. However, there is no report about Tfh cells in psoriasis.This study sought to analyze the blood Tfh cells in patients with psoriasis. I found no increased frequencies of circulating CXCR5+ Tfh cells, in disagreement with previous studies from several autoimmune diseases. However, the frequency of PD-1+ subset of activated Tfh cells decreased significantly in patients with psoriasis. Furthermore, the proportion and the absolute numbers of PD-1+ subset of activated Tfh cells negatively correlated with ESR levels. The proportion of PD-1+ Tfh cells and the absolute numbers of PD-1+ and ICOS+ Tfh cells were lower in psoriatic patients with high ASO titers. Meanwhile, the proportion of PD-1+ Tfh cells and the absolute numbers of PD-1+ and ICOS+ Tfh cells positively correlated with the disease duration of psoriasis. These findings suggest that the activated Tfh cells decrease in severe status and early phase of psoriasis. Furthermore, it also implies that B cell immunity weakens in psoriasis as a result of predominance of Th1 and Th17 cytokine axises. I expect that this elucidation of the altered frequency of activated Tfh cells will help the further investigation of pathogenesis and potential therapeutic targets in psoriasis.