Regulatory effect of vasoactive intestinal peptide on the balance of Treg and Th17 in collagen-induced arthritis.

Vasoactive intestinal peptide (VIP) is a well-known anti-inflammatory neuropeptide. The capacity of VIP can be exhibited through inhibiting inflammatory responses, shifting the Th1/Th2 balance in favor of anti-inflammatory Th2 immunity and inducing regulatory T cells (Tregs) with suppressive activity. In addition to pro-inflammatory Th1 response, Th17 are also believed to play important roles in the pathogenesis of rheumatoid arthritis (RA). In this study, we used collagen-induced arthritis (CIA) model in Wistar rats to investigate the role of VIP in the balance of CD4(+) CD25(+) Tregs and Th17 on RA. Data presented here showed that administration of VIP decreased incidence and severity of CIA. Disease suppression was associated with the upregulation of CD4(+) CD25(+) Tregs, downregulation of Th17- and Th1-type response and influence on the RANK/RANKL/OPG system. The results provide novel evidence that the therapeutic effects of VIP on CIA rats were associated with the balance of CD4(+) CD25(+) Tregs and Th17.