Bile Acid Regulates the Colonization and Dissemination ofCandida albicansfrom the Gastrointestinal Tract by Controlling Host Defense System and Microbiota

AbstractCandida albicans(CA), a commensal and opportunistic eukaryotic organism, frequently inhabits the gastrointestinal (GI) tract and causes life-threatening infections. Antibiotic-induced gut dysbiosis is a major risk factor for increased CA colonization and dissemination from the GI tract. We identified a significant increase of taurocholic acid(TCA),a major bile acid in antibiotic-treated mice susceptible to CA infection.In vivofindings indicate that administration of TCA through drinking water is sufficient to induce colonization and dissemination of CA in wild type and immunosuppressed mice. Treatment with TCA significantly reduced mRNA expression of immune genesang4andCxcr3in the colon. In addition, TCA significantly decreased the relative abundance of three culturable species of commensal bacteria,Turicibacter sanguinis, Lactobacillus johnsonii, andClostridium celatum, in both cecal contents and mucosal scrapings from colon. Taken together, our results indicate that TCA promotes fungal colonization and dissemination of CA from the GI tract by controlling host defense system and intestinal microbiota that play a critical role in regulating CA in the intestine.ImportanceBroad-spectrum antibiotics, FDA-approved bile acid drugs, and probiotics used to control metabolic and infectious diseases profoundly alter the level of TCA in the gut. Furthermore, TCA level is highly altered in a subset of cancer, colitis and surgery patients who are highly susceptible to CA infection. Inadvertently, these therapies and disease conditions could be either promoting CA colonization and dissemination. Our findings indicate that TCA alone can induce fungal colonization and dissemination from the intestine. Results from this study will have a significant impact in understanding how bile acids interact with the microbiota and host in regulating invasive fungal infections that originate from the intestine and to develop potential new antifungal therapeutics.