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, demonstrate potent anti-germination activity against <i>Clostridioides difficile</i> (<i>C. difficile</i>) spores, protecting rodents from <i>C. difficile</i> 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 the 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 deconjugated BAs in the feces, possibly suggesting increased activity of gut microbiota. Fecal levels of anti-<i>C. difficile</i> germination chenodeoxycholic acid and pro-germination taurocholic acid are significantly increased and decreased by the treatments, respectively. The hepatic transcriptome showed limited difference in gene expression between the three groups, suggesting a minimal adverse impact of the two compounds on liver function. Overall, our study suggests that in vivo CamSA and CA-Quin treatment demonstrated safe and significantly altered BA homeostasis that inhibits <i>C. difficle</i> germination.