Fecal microbiota transplantation ameliorates alcohol-associated liver disease through coordinated restoration of short-chain fatty acid and α-linolenic acid signaling.

BACKGROUND: Alcohol-associated liver disease (ALD) is closely linked to gut microbiota dysbiosis. However, the specific microbial metabolic functions that drive the transition from microbial imbalance to hepatic inflammation and metabolic injury remain unclear, limiting the development of mechanism-based therapeutic strategies. METHODS: This study integrated human microbiome analysis with fecal microbiota transplantation (FMT) experiments in an ALD mouse model. Multi-omics approaches, including 16S rRNA gene sequencing, untargeted metabolomics, and immunological profiling, were employed to systematically characterize the interactions among gut microbiota composition, microbial-derived metabolites, and host immune responses. RESULTS: We observed that ALD progression was characterized by an early shift in microbial composition followed by a marked decline in microbial diversity, culminating in an ecological collapse of the gut microbiota. FMT from healthy donors significantly improved liver histopathology and serum biochemical parameters, accompanied by restoration of gut microbial diversity and key metabolic functions. Metabolomic analyses revealed enhanced short-chain fatty acid (SCFA) production and activation of α-linolenic acid (ALA)-related metabolic pathways following FMT. These metabolic improvements were associated with reduced inflammatory responses and improved immune homeostasis. CONCLUSION: Our findings demonstrate that FMT from healthy donors ameliorates ALD by restoring critical microbial metabolic functions, particularly SCFA production and ALA-related pathways. These results highlight microbial metabolic function as a promising therapeutic target for microbiome-based interventions in ALD.