Bile Acid Analogs with Anti-germination Activities for Prophylaxis of Clostridioides difficile Infection Alter Bile Acid Homeostasis in the Enterohepatic Cycle

We previously reported that two bile acid (BA) analogs CamSA and CA-Quin demon-strate potent anti-germination activity against Clostridioides difficile (C. difficile) spores, protecting rodents from C. difficile infections. Here we further evaluated the impact of these analogs on the hepatic transcriptome and BA homeostasis in vivo by focusing BA profiles on the liver, feces, and chyme as well as hepatic transcriptome after a 7-day treatment. The two compounds demonstrated similar impact on BA profiles among the three samples, with significantly increased BA excretion in feces. This change is aligned with significantly altered expression of genes involved in BA homeostasis in both liver and gut tissues. Also, both compounds increased levels of unconjugated BAs in the feces, indicating an elevated activity of gut microbiota (GM). Notably, fecal levels of anti-c. difficile germination chenodeoxycholate and pro-germination taurocholate are signifi-cantly increased and decreased by the treatments, respectively. While hepatic tran-scriptome did not show significant toxicity, altered genes are enriched in pathways as-sociated with GM activity and lipid metabolism. Overall, our study suggests that in vivo CamSA and CA-Quin treatment demonstrated minimal hepatoxicity but significantly altered BA homeostasis and potentially favorable improvement for GM profiles that together inhibit C. difficle germination.