Taurodeoxycholic acid alleviates intestinal inflammation by modulating gut microbiota and TGR5-NF-kappaB axis in DSS-induced colitis.

Taurodeoxycholic acid (TDCA), a metabolite of cholesterol, has been shown to be able to regulate various inflammatory responses and improve intestinal inflammation. However, its potential to alleviate colitis through modulating the gut microbiota-bile acid axis remains unclear. Mice were simultaneously administered dextran sulfate sodium (DSS) and TDCA via drinking water to estimate the effect of TDCA on colitis. TDCA-treated mice showed markedly relieved DSS-induced colitis. 16S rDNA sequencing revealed TDCA selectively remodeled the gut microbiota, notably decreasing the abundances of Desulfovibrionaceae_unclassified, Escherichia-Shigella and increasing Akkermansia. Furthermore, the reshaping of the microbial community was functionally characterized by a marked alteration in the gut bile acid profile, specifically a significant increase in secondary bile acids. Fecal microbiota transplantation (FMT) confirmed the protective role of the TDCA-shaped microbiota, which also transferred the reduction of Desulfovibrionaceae_unclassified and the characteristic bile acid profile to recipient mice. Similarly, transplanting feces after TDCA intervention into recipient mice still increased secondary bile acid levels in the gut to a certain extent. Spearman's correlation analysis further solidified the negative correlation between Desulfovibrionaceae_unclassified and secondary bile acids. Mechanistically, the altered bile acid profiles restored the activation of the bile acid receptor TGR5, but not FXR, thereby inhibiting the NF-κB signaling pathway. The essential role of TGR5 was substantiated as its inhibitor, SBI-115, largely abolished the protective effects of TDCA. In conclusion, our findings demonstrate that TDCA alleviates colitis by orchestrating a microbiota-bile acid-TGR5 signaling cascade, positioning it as a promising therapeutic candidate for inflammatory bowel disease.