Objective. The goal of this study was to investigate whether microRNA-155 might be a potential therapeutic target for Behçet’s disease (BD). Methods. Expression levels of miR-155 were quantified using TaqMan microR-NA assays in peripheral blood mononuclear cells and in isolated CD4+ T cells from BD patients and healthy controls. To identify targets of miR-155, luciferase reporter assays and western blotting were performed. The effect of miR-155 on Th17 polarisation was analysed in patients with active BD by using flow cytometry and enzyme-linked immunosorbent assay.

Results. The expression of miR-155 and IL-17 was significantly increased in CD4+ T cells of patients with active BD. A luciferase reporter assay and western blot showed that Ets-1 expression was reduced by miR-155 mimics. Furthermore, the expression of Ets-1 was significantly decreased in patients with active BD compared to healthy controls. More importantly, repression of miR-155 in CD4+ T cells from active BD patients increased Ets-1 expression and reduced the number of IL-17-expressing T cells and overall IL-17 production. Conclusion. MiR-155 regulates the Th17 immune response by targeting Ets-1. Suppression of miR-155 reduced the amount of pathogenic IL-17-expressing T cells and may be a potential therapeutic strategy for BD.