MiR-223 improves intestinal inflammation through inhibiting the IL-6/STAT3 signaling pathway in dextran sodium sulfate-induced experimental colitis

Abstract

Background: The pathogenesis of inflammatory bowel disease (IBD) has not yet been clarified and is closely related to several proinflammatory factors. MicroRNA-233 (miR-223) might be involved in the development of IBD; however, the mechanism underlying its pathogenesis is unclear. In this study, we attempted to determine the role of miR-223 in dextran sodium sulfate (DSS)-induced colitis and explore the involvement of the IL-6/STAT3 pathway in the development of intestinal mucosal inflammation.Methods: Male C57BL/6 mice were divided into six groups: control (WT) group, DSS group, DSS+miR-223 agomir (DSS+A) group, DSS+miR-223 agomir negative control (DSS+A+NC) group, DSS+miR-223 antagomir (DSS+AN) group and DSS+miR-223 antagomir negative control (DSS+AN+NC) group. Body weight, stool consistency, fecal blood and the disease activity index (DAI) score were recorded daily. The length of each colon was measured, and colonic inflammation was evaluated with hematoxylin and eosin (H&E) staining and histopathological scoring. The expression of myeloperoxidase (MPO), TNF-α, IL-6, IL-10 and IL-17 in the colonic tissues was measured by Enzyme-linked Immunosorbent Assay (ELISA) and real-time quantitative polymerase chain reaction (RT-qPCR). The mRNA expression of gp130, Bcl-2 and Bcl-xl in the colon was measured using RT-qPCR. The colonic levels of STAT3 and p-STAT3 were determined by Western blotting.Results: MiR-223 expression in the terminal ileum and colon was increased in the DSS group compared with the WT group. Colitis symptoms were significantly alleviated in the DSS+A group and exacerbated in the DSS+AN group after administration of the miR-223 agomir and antagomir, respectively. MPO, TNF-α, IL-6 and IL-17 were decreased and IL-10 was increased in the DSS+A group, but these changes were reversed in the DSS+AN group. Gp130 mRNA, p-STAT3, Bcl-2 and Bcl-xl in the colon declined in the DSS+A group, but these levels increased in the DSS+AN group.Conclusion: The upregulation of miR-223 by agomir administration alleviated colonic inflammation in a DSS-induced colitis model, which was likely mediated by inhibiting the production of proinflammatory cytokines via the IL-6/STAT3 signaling pathway. These findings provide evidence that miR-223 might have potential therapeutic implications in IBD.