GV-971 remodels the gut microbiota-bile acid-FXR axis to ameliorate obesity and metabolic dysfunction.

Obesity and its associated metabolic complications represent a global health crisis, yet effective microbiota-targeted pharmacotherapies remain limited. Here, we report that GV-971 (sodium oligomannate), a marine-derived oligosaccharide originally developed for Alzheimer's disease, exerts potent anti-obesity and metabolic benefits by reprogramming gut microbial and host signaling networks. In high-fat diet-induced obese mice, GV-971 reduced adiposity, improved glucose homeostasis, and alleviated hepatic steatosis without affecting food intake. Multi-omics and causal intervention experiments revealed that GV-971 selectively decreased the abundance of Clostridium scindens, a keystone bacterium responsible for secondary bile acid synthesis. This decrease downregulated the expression of the baiF gene encoding 7α-hydroxysteroid dehydrogenase, leading to reduced intestinal deoxycholic acid (DCA) levels and inhibition of intestinal farnesoid X receptor (FXR) signaling. Restoration of C. scindens abundance, baiF expression, or DCA supplementation abrogated the metabolic benefits of GV-971, confirming the causal role of the C. scindens-DCA-FXR axis. Mechanistically, inhibition of intestinal FXR promoted thermogenic gene expression and white adipose tissue browning, thus enhancing systemic energy expenditure. These findings uncover a bacterium-metabolite-host signaling pathway underlying the effects of GV-971 and establish microbiota-directed FXR modulation as a promising therapeutic approach for obesity and metabolic disease.