P149 Bacteroides uniformis ameliorates pro-inflammatory diet-exacerbated colitis by targeting endoplasmic reticulum stress-mediated ferroptosis

Abstract Background Pro-inflammatory diet is positively associated with the risk and progression of inflammatory bowel diseases. Recently, ferroptosis was observed in patients with dietary pattern-associated colitis. However, the mechanisms underlying the effects of a pro-inflammatory diet and whether it mediates ferroptosis are unknown. This study aimed to clarify the mechanisms of pro-inflammatory diet in colitis. Methods Mice were fed a dietary inflammatory index-based pro-inflammatory diet for 12 weeks. Subsequently, colitis was chemically induced using 2.5% dextran sulfate sodium with or without a ferroptosis inhibitor (ferrostatin-1). Body weight, histological scores, immune response, and mucosal barrier function were evaluated to assess intestinal inflammation.Colon tissue transcriptomics, fecal microbiome, and serum metabolomics were applied to identify diet-microbe-host interactions. Dietary inflammatory index of 36 patients with Crohn’s disease were evaluated. Their intestinal specimens were also collected. The biological functions of Bacteroides uniformis were observed in vitro and in vivo. Results Pro-inflammatory diet induced low-grade intestinal inflammation and exacerbated colitis by activating glutathione peroxidase 4-associated ferroptosis in the endoplasmic reticulum stress-mediated pathway; ferrostatin-1 treatment reversed this pro-inflammatory potential. Additionally, the pro-inflammatory diet triggered colitis by modulating the gut microbiota and metabolites. Notably, supplementation with B. uniformis improved the pro-inflammatory diet-aggravated colitis by inhibiting endoplasmic reticulum stress-mediated ferroptosis. Co-culturing B. uniformis with intestinal epithelial cells revealed it is non-enterotoxigenic and non-enteroinvasive. Conclusion Pro-inflammatory diet drives colitis by targeting endoplasmic reticulum stress-mediated ferroptosis, possibly in a gut microbiota-dependent manner. Pro-inflammatory diet restriction and microbial-based therapies may be effective strategies for preventing and treating inflammatory bowel disease.