Modulating effects of Lactobacillus acidophilus LA15 on immune response and gut microbiota in cyclophosphamide-induced immunosuppressed mice.

The gut microbiota plays a fundamental role in modulating host immune homeostasis. Lactobacillus (L.) acidophilus, as a predominant probiotic, has garnered significant research interest for its potential immunoregulatory capabilities. In this study, a strain of L. acidophilus, designated LA15, was selected based on its superior performance in promoting RAW264.7 cell viability, gastrointestinal tolerance, and in vitro adhesion. Using a cyclophosphamide (CTX)-induced immunosuppressed mouse model, we demonstrated LA15 administration significantly increased body weight, enhanced organ indices, and elevated serum cytokine levels. Additionally, LA15 contributed to the preservation of intestinal tissue integrity and enhances barrier function. Moreover, it modulated the composition of the gut microbiota, promoting a balanced microbial ecosystem. Specifically, LA15 administration leads to an increased relative abundance of beneficial genera such as unclassified_Muribaculaceae, Lachnospiraceae_NK4A136, Lactobacillus, and Candidatus_Saccharimonas, while reducing populations of opportunistic pathogens including Desulfurvibrio and Helicobacter. These findings suggest that LA15 possesses notable immunostimulatory effects and could serve as a promising candidate for ameliorating immunosuppression-related conditions.