Probiotic properties of Lacticaseibacillus paracasei MJ4 and its protective effect on mice with inflammatory bowel disease: A potential probiotic resource

Intestinal inflammation in animals is a common intestinal disease, among which Crohn's disease (CD) and ulcerative colitis (UC) are the most common. However, probiotics are strain-specific, and there are significant differences in the mechanisms of action among different strains. In this study, Lacticaseibacillus paracasei MJ4 was isolated from the homemade yogurt of herdsmen in Qinghai Province, China. In vitro experiments demonstrated that MJ4 possesses excellent probiotic properties and safety profiles. In a murine model of colitis, MJ4 alleviated weight loss and colon shortening, and reduced the DAI score. After intervention with MJ4, the levels of pro-inflammatory factors (IL-1β, TNF-α, and IL-6) and histopathological scores decreased, whereas the level of IL-10 and the number of goblet cells increased significantly. Additionally, MJ4 rebalanced the intestinal flora composition in colitis mice by increasing the abundance of Faecalibaculum and Alistipes , and decreasing the abundance of Bacteroides , Escherichia_Shigella , and Akkermansia . Collectively, these findings indicate that L. paracasei MJ4 holds substantial potential for preventing colitis. • Lacticaseibacillus paracasei MJ4 was isolated from homemade yogurt produced by herdsmen in Qinghai Province, China. • Compared with modern dairy products, those produced using traditional techniques are more ecologically natural and contain a richer diversity of lactic acid bacteria. Lactic acid bacteria derived from traditional dairy products also exhibit higher safety profiles. • MJ4 has stronger environmental tolerance, can survive under the harsh conditions of gastric acid and bile, and has a certain degree of adhesiveness. After entering the intestine, it can significantly improve the intestinal colonization rate.