Metformin-associated gut microbiota remodeling correlates with reinvigorated splenic immunity in aged mice: microbiome-immune crosstalk via the gut-spleen axis

Metformin reshapes the gut microbiota, which is associated with mitigation of age-associated splenic immune dysregulation, favoring anti-inflammatory macrophage polarization and cytotoxic T cell expansion. Critically, our findings establish the gut-spleen axis as a key mediator of splenic immunosenescence and a novel therapeutic target, which positions metformin as a promising microbiota-directed geroprotective agent. Future research should prioritize mechanistic dissection of gut-spleen communication and clinical validation of metformin's geroprotective efficacy in human populations.