Microbiological treatments are expected to have a role in the future management of inflammatory bowel disease (IBD). Clostridium butyricum (C. butyricum) is a probiotic microorganism that exhibits beneficial effects on various disease conditions. Although many studies have revealed that C. butyricum provides protective effects in mice with colitis, the way C. butyricum establishes beneficial results in the host remains unclear. In this study, we investigated the mechanisms by which C. butyricum modifies the gut microbiota, produces bacterial metabolites that may be involved, and, specifically, how microbial extracellular vesicles (EVs) positively influence IBD, using a dextran sulfate sodium (DSS)-induced colitis murine model in mice. First, we showed that C. butyricum provides a protective effect against colitis, as evidenced by the prevention of body weight loss, a reduction in the disease activity index (DAI) score, a shortened colon length, decreased histology score, and an improved gut barrier function, accompanied by reduced levels of pathogenic bacteria, including Escherichia/Shigella, and an increased relative abundance of butyrate-producing Clostridium sensu stricto-1 and Butyricicoccus. Second, we also confirmed that the gut microbiota and metabolites produced by C. butyricum played key roles in the attenuation of DSS-induced experimental colitis, as supported by the profound alleviation of colitis effects following fecal transplantation or fecal filtrate insertion supplied from C. butyricum-treated mice. Finally, C. butyricum-derived EVs protected the gut barrier function, improved gut microbiota homeostasis in ulcerative colitis, and contributed to overall colitis alleviation. IMPORTANCE This study indicated that C. butyricum provided a prevention effect against colitis mice, which involved protection of the intestinal barrier and positively regulating gut microbiota. Furthermore, we confirmed that the gut microbiota and metabolites that were induced by C. butyricum also contributed to the attenuation of DSS-induced colitis. Importantly, C. butyricum-derived EVs showed an effective impact in alleviating colitis.
Keywords: Clostridium butyricum; colitis; extracellular vesicles; gut barrier function; gut microbiota.