Lactobacillus vaginalis alleviates DSS induced colitis by regulating the gut microbiota and increasing the production of 3-indoleacrylic acid

Ulcerative colitis (UC) is a chronic inflammatory disorder, and its incidence is experiencing an upward trend worldwide. UC can result in gut microbiota dysbiosis, impaired intestinal epithelial barrier, and systemic inflammation, for all of which there is presently no definitive treatment available. Lactobacillus is known to regulate gut microbiota and related metabolites to intervene in the development of UC. The objective of this study was to explore the underlying mechanism through which a novel probiotic, Lactobacillus vaginalis, alleviates DSS-induced colitis. Specifically, L. vaginalis were found to ameliorate the DSS-induced UC phenotype, restore intestinal microbiota balance and intestinal barrier function, and elevate the levels of 3-indoleacrylic acid (IAA) in mouse feces. Furthermore, fecal microbiota transplantation and fecal filtrate transplantation provide additional evidence that L. vaginalis alleviate DSS-induced colitis through metabolic products. Additionally, IAA has been shown to alleviate DSS-induced colitis symptoms, decrease inflammatory responses, and enhance intestinal barrier function. Finally, our findings confirm that L. vaginal and metabolites possess the capability to regulate the immune microenvironment in mice with colitis. And the RNA-seq analysis suggests that L. vaginal may play a pivotal role in alleviating colitis by modulating the PPAR signaling pathway. In conclusion, our findings suggest that oral administration of L. vaginalis alleviates DSS induced colonic inflammation by increasing the levels of IAA. L. vaginalis, as an emerging probiotic, provides a potential therapeutic strategy for clinical UC.