NR1H4 and urinary bladder carcinoma: The GBA, defined as a bidirectional network linking the gut and bladder via microbial communities, metabolites, immune signaling, and neural pathways (10, 11), operates via three core mechanisms: (1) The gut microbiota regulate the bladder microenvironment through metabolites (e.g., short-chain fatty acids); (2) Cross organ regulation mediated by neural pathways (such as vagus nerve) and shared receptors (e.g., FXR); (3) Immune factors affect the occurrence and development of bladder cancer through inflammatory reaction.