OP31 High fat diet exacerbates colitis through microbial metabolite deoxycholic acids induced-ferroptosis

Abstract Background High-fat diet (HFD) is closely related to the occurrence and development of IBD, which increases the level of deoxycholic acid (DCA). DCA-treated mice showed pro-inflammatory cell infiltration and colonic inflammation. Ferroptosis, a newly recognized form of cell death characterized by iron overload and the generation of reactive oxygen species (ROS) has recently been observed in colitis. Whether DCA affects ferroptosis and whether it contributes to colitis has not been explored. Methods Twenty-four Female C57BL/6 mice were randomly divided into 4 groups: control group, DCA group, DSS group, and DSS plus DCA group. Real-time PCR and Western blotting were used to detect the transcription and protein expression of ferroptosis-related genes. RNA sequencing was used to analyze the changes of differential genes in the intestinal tissue of mice treated with DCA. Transmission electron microscope was employed to observed the changes of intestinal epithelial cell morphology and intracellular mitochondria. Finally, the binding force between DCA and HIF-2α was calculated by molecular dynamics to explore the structural biological basis of the interaction between DCA and HIF-2α, and screen innovative drugs. Results We found that DCA exacerbated the disease activity index, histological damage and cell death in mice with colitis. In vivo, ferroptosis KEGG pathway was enriched by RNA sequencing in colonic tissues. DCA treatment significantly induced ferroptosis in DSS-induced mice, as evidenced by iron overload, ROS and MDA production, accompanied by decreased expression of GPX4 and increased expression of ACSL4. Transmission electron microscopy also confirmed the occurrence of ferroptosis in colonic tissues. In vitro, DCA induced ferroptosis were also observed in IEC-6 cells and Caco-2 cells under the combined treatment of Lipopolysaccharide (LPS). Interestingly, RNA sequencing revealed that the expression levels of the apical iron divalent metal transporter-1 (DMT1) were significantly upregulated in DCA treated-mice with colitis. DMT1 is a direct target gene of hypoxia inducible factor (HIF)-2α. We also found that DCA could increase the level of DMT1 and HIF-2α in the intestinal epithelial cell lines. Pharmacological inhibition of HIF-2α significantly inhibited the expression of DMT1 and blocked the promotion of ferroptosis by DCA. These data provide a mechanistic basis for the widely reported link between ferroptosis and colitis risk. Conclusion Taken together, these findings suggest that DCA aggravates colitis through the induction of ferroptosis in the HIF2α-DMT1 signaling pathway and provides a new perspective for UC prevention in the future.