Background: The imbalance between Th17 and regulatory T (Treg) cells,and their related cytokines,have been associated with the pathogenesis of Inflammatory Bowel Disease (IBD).Total glycosides of paeony (TGP) is an alternative immunomodulatory agent that is widely used for the treatment of autoimmune disease.In this study,we aimed to evaluate the modulatory effect of TGP in a rat model of colitis induced by 2,4,6-trinitrobenzene sulfonic acid (TNBS).Methods: TGP was administered intragastrically 24 hours after the TNBS intrarectal instillation for 7 days.Clinical manifestation,colon macroscopic and histopathological score were evaluated.Expressions of (IL)-17,IL-6,tumor necrosis factor-a (TNF-α),IL-10,transforming growth factor-β (TGF-β) were detected.The differentiation of Th17/Treg cells in splenocytes was studied by flow cytometry.Results: TGP treatment not only ameliorated the clinical status,but also abrogated the histopathologic severity of acute TNBS colitis.Furthermore,TGP inhibited the levels of IL-17,IL-6,TNF-cα,while increased the expressions of IL-10,TGF-β.Additionally,TGP reduced the percentages of Th17 cells,but enhanced the propotion of Treg cells in the spleen and MLNs.We also observed a suppression of retinoidrelated orphan receptor-γt (ROR-γt).However,expression of Forkhead boxp3 (Foxp3) was increased with the treatment of TGP.Conclusions: Our results suggest that TGP plays a regulatory role in modulating the balance of Th17 and Treg cells to ameliorate the TNBS-induced colitis,and support the strategy of using TGP to treat IBD.