IL-9-producing Th9 cells may participate in pathogenesis of Takayasu's arteritis.

Takayasu's arteritis (TAK) is a type of large vessel vasculitis which involves the aorta and its major branches. Interleukin (IL)-9 or IL-9-producing Th9 cells were found to be involved in pathogenesis of autoimmune arteritis such as giant cell arteritis, but IL-9 or Th9 cells in TAK were not well known. Here, this study aims to analyze the levels of serum IL-9 and their major source Th9 cells in TAK. With the help of cytometric bead array (CBA), a total of 21 patients with TAK were examined for serum levels of cytokines IL-4, IL-6, IL-8, IL-17, IL-10, TNF-α, IFN-γ, and IL-9. Flow cytometry techniques were used to examine the frequencies of Th9 cells from peripheral blood mononuclear cells (PBMCs) for 11 patients with active TAK and 10 healthy controls. Higher serum levels of serum IL-6 (P < 0.05), TNF-α (P < 0.05), and IL-9 level (P < 0.05) were observed in TAK patients compared to those of healthy controls. Higher frequencies of CD4(+) IL-9(+) T cells and CD4(+) PU.1(+) T cells in PBMCs and IL-9(+) PU.1(+) T cells in CD4(+) T cells were observed in active TAK patients than those in healthy controls (all P < 0.01). The levels of IL-9 had a positive correlation with ESR (r = 0.975, P = 0.015) in these cases. Our data suggested that Th9 cells and IL-9 could possibly be involved in the pathogenesis of TAK.