Christensenella massiliensis reduces kynurenine levels and alleviates obesity and related metabolic disorders in model mice.

Next-generation probiotics derived from gut commensals show promise for metabolic disease intervention, yet effective anti-obesity strains remain limited. Here, we demonstrate that oral administration of Christensenella massiliensis markedly alleviates obesity and metabolic dysfunction in high-fat diet-induced obese mice. Treatment reduced food intake, improved glucose tolerance and insulin sensitivity, lowered blood glucose and lipid levels, and attenuated hepatic steatosis and adipose accumulation. C. massiliensis increased the levels of plasma GLP-1 and ileal GLP-1 receptor expression while decreasing ghrelin level, suggesting modulation of gut hormone regulation. C. massiliensis also suppressed systemic and colonic inflammation, accompanied by upregulation of metabolic homeostasis-related genes (ppara, pparg, ucp2). Targeted and quantitative metabolomics identified altered gut metabolic profiles, particularly reduced kynurenine levels. In vitro assays further showed that C. massiliensis converted kynurenine into kynurenic acid, and its lysate reversed kynurenine-induced lipid accumulation, inflammation, and PPARγ suppression in hepatocytes, providing mechanistic support for the observed in vivo metabolic benefits. These findings support C. massiliensis as a promising next-generation probiotic for obesity management.