Iguratimod ameliorates inflammatory responses by modulating the Th17/Treg paradigm in dextran sulphate sodium-induced murine colitis

Inflammatory bowel disease (IBD) is an autoimmune disease with an abnormal and persistent immune response. Iguratimod, a novel anti-rheumatic drug, exhibits anti-inflammatory effects and regulates immune response. The role of iguratimod in intestinal mucosal inflammation and immunity has not been examined. The aim of this study was to investigate whether iguratimod ameliorates dextran sulphate sodium (DSS)-induced murine colitis and its potential regulatory mechanism. Murine colitis was induced by administering 2.5% DSS for 5 days. Some mice were administered iguratimod (5, 30 mg/kg) by oral gavage once daily for 7 days, beginning on the day 3 after colitis induction. Our study showed that iguratimod alleviates the symptoms of colitis and suppresses intestinal tissue damage, including macroscopic and histopathological manifestations. Moreover, iguratimod reduced interleukin (IL)-6, IL-17, and tumour necrosis factor-α levels, and increased the expression levels of IL-10 and TGF-β. In addition, iguratimod downregulated the proportion of Th17 cells, the level of transcription factor retinoic acid-related orphan receptor γt (RORγt), and the phosphorylation of signal transducer and activator of transcription-3 (STAT3), and upregulated the proportion of Treg cells, the level of transcription factor forkhead box p3 (Foxp3), and the phosphorylation of STAT5 in the colonic tissues. In conclusion, iguratimod plays a protective role in mice with DSS-induced colitis via anti-inflammatory effects and regulation of Th17/Treg cells. Therefore, use of iguratimod may serve as a novel therapeutic strategy for the treatment of IBD.