The microbial metabolite Urolithin A reduces C. difficile toxin expression and repairs toxin-induced epithelial damage

Clostridioides difficile is a gram-positive, anaerobic, spore-forming bacterium that is responsible for antibiotic-associated pseudomembranous colitis. Clostridioides difficile infection (CDI) symptoms can range from diarrhea to life-threatening colon damage. Toxins produced by C. difficile (TcdA and TcdB) cause intestinal epithelial injury and lead to severe gut barrier dysfunction, stem cell damage, and impaired regeneration of the gut epithelium. Current treatment options for intestinal repair are limited. In this study, we demonstrate that treatment with the microbial metabolite urolithin A (UroA) attenuates CDI-induced adverse effects on the colon epithelium in a preclinical model of CDI-induced colitis. Moreover, our analysis suggests that UroA treatment protects against C. difficile-induced inflammation, disruption of gut barrier integrity, and intestinal tight junction proteins in the colon of CDI mice. Importantly, UroA treatment significantly reduced the expression and release of toxins from C. difficile, without inducing bacterial cell death. These results indicate the direct regulatory effects of UroA on bacterial gene regulation. Overall, our findings reveal a novel aspect of UroA activities, as it appears to act at both the bacterial and host levels to protect against CDI-induced colitis pathogenesis. This research sheds light on a promising avenue for the development of novel treatments for C. difficile infection.