A multi-organ atlas links gut microbial metabolites to systemic redox changes in aging mice

Aging disrupts systemic metabolism, but the mechanisms by which gut microbial metabolites drive tissue-specific decline remain unclear. We conducted a multi-organ, multi-omics atlas across the gut, serum, liver, lung, and cortex in young and middle-aged mice to address this. We identified a conserved aging signature marked by the microbiota-associated depletion of protective circulating metabolites, such as lysophosphatidylcholines (LPCs), concurrently with the systemic accumulation of pro-oxidative microbial catabolites, specifically trimethylamine N-oxide (TMAO) and indole-3-acetic acid (IAA). This microbial-metabolic drift disrupted systemic lipid transport and redox balance, leading to distinct organ-level vulnerabilities: hepatic lipid retention and ferroptosis susceptibility, pulmonary immune-redox activation, and cortical neurochemical dysregulation. To establish functional relevance, we conducted an integrated meta-analysis of 50 independent studies encompassing natural aging models, fecal microbiota transplantation (FMT), and probiotic interventions. This quantitative synthesis provided convergent evidence that microbial remodeling is a functionally relevant correlate associated with systemic aging phenotypes by restoring intestinal barrier integrity (upregulating ZO-1, MUC2), suppressing tissue inflammatory factors (IL-6, IL-1β, TNF-α), and mitigating oxidative stress (reducing MDA and restoring SOD/GSH). Together, our findings highlight gut-derived metabolic reprogramming as a modifiable, upstream driver of systemic aging, offering tractable targets for therapeutic intervention.