<b>Microbial-Derived Metabolites as Modulators of Host Inflammatory and Metabolic Signaling: </b><b>Mechanisms and Dietary Intervention Strategies</b>

The gut microbiota produces bioactive metabolites—such as short chain fatty acids (SCFAs), indoles, and trimethylamine-N-oxide (TMAO), that critically regulate host metabolic and inflammatory pathways, with direct implications for obesity, type 2 diabetes, and non-alcoholic fatty liver disease (NAFLD). Despite growing interest in the diet-microbiota-health axis, the mechanistic links between specific dietary components, microbial metabolite production, and downstream signaling (e.g., via aryl hydrocarbon receptor [AhR] or G-protein-coupled receptors [GPR41/43]) remain poorly understood. This study investigates how microbial metabolites modulate key inflammatory (NF-κB/NLRP3) and metabolic (AMPK/mTOR) networks and evaluates dietary interventions (e.g., prebiotics, polyphenols) as therapeutic tools to reshape these interactions. Using an integrated multi-omics approach, combining metagenomics and metabolomics in a human cohort (n=100, lean/obese) with in vitro (Caco-2/HT-29 cells) and in vivo (high-fat diet murine model) experiments, we dissect the molecular pathways linking metabolite profiles to clinical outcomes (e.g., insulin resistance, systemic inflammation). Our findings reveal that propionate surpasses butyrate in suppressing NLRP3 inflammasome activation via GPR43 in adipocytes, while indole-3-acetate (derived from cruciferous vegetables) emerges as a potent AhR ligand, ameliorating hepatic steatosis. By correlating host transcriptomics with fecal metabolomics, we identify distinct "metabolite signatures" predictive of dietary responsiveness, offering a roadmap for precision nutrition strategies. This work bridges critical gaps between microbial ecology, host biochemistry, and translational medicine, providing actionable insights for targeting the gut-liver axis in metabolic disorders.