Ruscogenin Attenuates Ulcerative Colitis in Mice by Inhibiting Caspase-1-Dependent Pyroptosis via the TLR4/NF-κB Signaling Pathway

Inflammatory bowel diseases (IBD) are chronic inflammatory disorders affecting the digestive tract, including ulcerative colitis and Crohn's disease. Ruscogenin, a prominent steroidal sapogenin present in radix ophiopogon japonicus, has shown a protective effect on attenuating the inflammatory response associated with inflammatory diseases, but the efficacy of ruscogenin in IBD remains unclear. The aim of this study is to explore the effect of ruscogenin on intestinal barrier dysfunction and inflammatory responses as well as the underlying mechanism in ulcerative colitis. A dextran sulfate sodium salt (DSS)-induced C57BL/6 mouse colitis model was employed for the in vivo studies, while in vitro experiments were performed in THP-1 cells and human intestinal epithelial cells involved in inducing inflammatory responses and pyroptosis using LPS/nigericin. The results indicated that ruscogenin treatment attenuated the symptoms of ulcerative colitis, reduced the release of inflammatory cytokines and the expression of pyroptosis-associated proteins, and restored the integrity of the intestinal epithelial barrier in colon tissue in mice. Moreover, ruscogenin inhibited LPS/nigericin-induced pyroptosis in THP-1 cells. Mechanically, ruscogenin inhibited NLRP3 inflammasome activation and canonical pyroptosis, at least in part, through the suppression of the TLR4/NF-kappa B signaling pathway. These findings might provide new insights and a solid foundation for further exploration into the therapeutic potential of ruscogenin in the treatment of IBD.