Modulation of Bacteroides fragilis-driven bile acid metabolism in stroke-associated enterotypes by Eucommia ulmoides extract and Limosilactobacillus reuteri

Abstract

Gut microbiota dysbiosis influences the risk of ischemic stroke (IS). Diet and natural products can modulate the microbiota to prevent disease. This study investigated the relationship between specific enterotypes and bile acids in individuals with irritable bowel syndrome (IBS) and assessed the therapeutic effects of Eucommia ulmoides extract (EU) and Limosilactobacillus reuteri (L. reuteri). Public metagenomic data from IS patients and healthy controls were used to classify the gut microbiota. Constraint-based metabolic models (COBRA) were employed to predict microbial metabolic features. Machine learning (XGBoost-SHAP) was utilized to identify key microbes and metabolites. In vitro experiments explored the interactions between Bacteroides fragilis (B. fragilis) and L. reuteri plus EU extract. Furthermore, a PC12 and Caco-2 co-culture cell model was used to validate their effects on the gut-brain axis. The Bacteroidaceae-dominant enterotype (ET-B) is associated with a higher risk of IS, while the Lachnospiraceae-dominant enterotype (ET-L) is associated with a lower IS risk. ET-B, enriched with B. fragilis, increases the production of deoxycholic acid (DCA), thereby impairing brain and gut function. The combined intervention of L. reuteri and EU extract, particularly the addition of EU, significantly inhibited B. fragilis growth and DCA production, improved intestinal barrier function by upregulating phosphorylation of AMPKα and zonula occludens-1, and demonstrated neuroprotective effects via upregulating the phosphorylation of AKT (p < 0.05).

In conclusion, ET-B and ET-L represent high-risk and protective enterotypes for IS, respectively, with B. fragilis-derived DCA serving as a key mediator of gut-brain axis dysregulation in stroke pathogenesis. The synergistic effects of EU extract and L. reuteri in ameliorating gut-brain axis dysfunction open new therapeutic possibilities for natural product-based stroke prevention and treatment strategies.