Abstract
High-fat diet (HFD) disrupts gut microbiota homeostasis, induces intestinal barrier damage and systemic inflammation, ultimately leading to insulin resistance and hepatic glucose metabolism disorders. This study investigated the therapeutic effects of Lacticaseibacillus rhamnosus HF01 (L. rhamnosus HF01) -derived postbiotic (cell-free supernatant, CFS; defined as metabolites derived from probiotics) on HFD-induced metabolic dysregulation and its regulatory mechanisms via the gut-liver axis. The findings revealed that CFS suppressed pro-inflammatory genera (Bacteroides, Colidextribacter, Helicobacter, and Butyricimonas) while enriching beneficial genera such as Muribaculum, norank_f__Muribaculaceae, Odoribacter, unclassified_f__Lachnospiraceae, and norank_f__Ruminococcaceae. Concurrently, CFS drove tryptophan metabolic reprogramming, significantly elevating levels of IAA, TA, and 5-HIAA while reducing 5-HT production. These changes enhanced intestinal tight junction protein expression and inhibited LPS-triggered inflammatory responses. Furthermore, CFS activated the IRS/PI3K/Akt signaling pathway, reversing HFD-induced insulin resistance and glucose metabolism abnormalities. This study elucidated the regulatory mechanisms of CFS in ameliorating metabolic disorders via the gut-liver axis, providing theoretical support for intervention strategies targeting gut microbiota-derived metabolites.