Blockade of IL-7Rα alleviates collagen-induced arthritis via inhibiting Th1 cell differentiation and CD4 T cell migration.

T cell response is crucial to the pathogenesis and progression of rheumatoid arthritis (RA). IL-7/IL-7R axis has significant effect on CD4 T cell response, including proliferation, differentiation, survival and migration. However, whether blockade of IL-7/IL-7R axis signaling can relieve RA and what is the potential treatment mechanisms are still remaining unclear. In this paper, we established collagen-induced arthritis (CIA) model and observed the effect of IL-7Rα antibody in the treatment of CIA mice. It is demonstrated that IL-7Rα antibody significantly alleviated clinical symptoms of CIA mice, accompanied with reduced CD4 T cell number in both spleen and joints. Decreased CII-specific CD4 T cell proliferation and reduced mRNA expression of inflammatory cytokines in IL-7Rα antibody-treated mice were observed. Subsequently, IL-7Rα antibody treatment in vivo downregulated the percentages of Th1 and Th17 cells and the mRNA expression of T-bet and RORγt gene. Moreover, it was found that IL-7 promoted Th1 cell differentiation in vitro, while having no effect on Th17 cell differentiation. In addition, administration of IL-7Rα antibody reduced the mRNA expression of chemokine receptors (CCR7, CXCR3, CXCR6 and XCR1) on CD4 T cells and chemokine CXCL2 in joints. The results suggested that IL-7Rα antibody treated CIA mice via the inhibition of CII-specific CD4 T cell proliferation, the reduction of Th1 cell differentiation and the restrain of CD4 T cell migration to joint lesion site. This investigation indicates that IL-7Rα is a potential therapeutic target for RA.