Contribution of Th2-like Treg cells to the pathogenesis of Takayasu's arteritis.

OBJECTIVES: Takayasu's arteritis (TAK) involves inflammatory vasculitis of large vessels and mainly affects the aorta and its major branches. Abnormal immunity may play a vital role in TAK pathogenesis. Regulatory T cells (Treg cells) are important for peripheral tolerance, but under certain conditions Treg cells can differentiate into Th-like cells that have lost immune suppressive function and promote the development of autoimmune diseases. The role of Th-like Treg cells in TAK is unclear and this study aims to investigate the function of Th-like Treg cell subsets and associated cytokines in TAK. METHODS: A total of 51 patients with TAK and 32 healthy controls were enrolled. The percentage of Th1, Th2, Th17, Tregs and Th-like Treg cells in blood samples was analyzed by flow cytometry. Serum cytokine levels were detected using a cytometric bead array for cytokines. RESULTS: TAK patients had decreased numbers of Th2-like Treg cells in the peripheral blood (p=0.002) relative to healthy controls. The percentage of Treg cells in samples from TAK patients also decreased (p=0.002), but the Th2 cell percentage (p=0.04) increased compared to healthy controls. TAK patients had higher serum levels of IL-4 (p<0.001) and IL-13 (p<0.001) than healthy controls, and levels of both cytokines correlated to IL-6 levels. CONCLUSIONS: We studied changes in T helper-like Treg cell subsets in TAK for the first time and discovered that the number of Th2-like Treg cells in peripheral blood decreased. Results of this study suggested that Th2-like Treg cells could contribute to TAK pathogenesis.