Lacticaseibacillus paracasei PS23 Effectively Modulates Gut Microbiota Composition and Improves Gastrointestinal Function in Aged SAMP8 Mice.

Probiotics are reported to improve gastrointestinal (GI) function via regulating gut microbiota (GM). However, exactly how probiotics influence GM and GI function in elders is poorly characterized. Therefore, in this study, we assessed the effect of the probiotic Lacticaseibacillus paracasei PS23 (LPPS23) on the GM and GI function of aged mice. There were four groups of senescence-accelerated mouse prone-8 (SAMP8) mice (n = 4): a non-treated control group, a saline control group, a low dose LPPS23 group (1 × 108 colony-forming unit (CFU)/mouse/day), and a high dose LPPS23 group (1 × 109 CFU/mouse/day). Non-treated mice were euthanized at 16 weeks old, and others were euthanized at 28 weeks old. The next-generation sequencing results revealed that LPPS23 enriched Lactobacillus and Candidatus_Saccharimonas, while the abundance of Lachnospiraceae_UCG_001 decreased in aged mice given LPPS23. The abundance of Lactobacillus negatively correlated with the abundance of Erysipelotrichaceae. Moreover, LPPS23 improved the GI function of aged mice due to the longer intestine length, lower intestinal permeability, and higher phagocytosis in LPPS23-treated mice. The ELISA results showed that LPPS23 attenuated the alterations of pro-inflammatory factors and immunoglobulins. The abundance of LPPS23-enriched Lactobacillus was positively correlated with healthy GI function, while Lachnospiraceae_UCG_001, which was repressed by LPPS23, was negatively correlated with a healthy GI function in the aged mice according to Spearman's correlation analysis. Taken together, LPPS23 can effectively modulate GM composition and improve GI function in aged SAMP8 mice.