Beyond these established mechanisms, we propose a unifying "gut-immune-metabolic axis" in which immunosuppression-induced gut microbiota dysbiosis-characterized by depletion of short-chain fatty acid-producing taxa (Roseburia, Faecalibacterium prausnitzii) and Akkermansia muciniphila-drives intestinal barrier dysfunction, endotoxemia, impaired FXR/TGR5-mediated GLP-1 secretion, and TMAO-associated metabolic inflammation, collectively perpetuating glucose dysregulation. Here, GPBAR1 is linked to serum lipopolysaccharide activity.