Segatella copri and gut microbial ammonia metabolism contribute to chronic kidney disease pathogenesis.

Alterations in gut microbiota have been linked to chronic kidney disease (CKD), but large-scale studies and mechanistic insights are limited. Here we analysed gut metagenome data from 1,550 older individuals (aged 65-93 years) with comprehensive kidney function measurements. Segatella copri was positively associated with kidney function through microbial ammonia metabolism-related pathways and the asnA gene, which encodes an ammonia-assimilating enzyme. These associations were replicated in two external studies. In mice, ammonia supplementation increased serum levels of creatinine and blood urea nitrogen, accelerating CKD progression. In vitro cultures of S. copri or asnA-overexpressing Escherichia coli reduced ammonia concentrations, which was markedly attenuated in asnA-knockout S. copri. Gavage of either S. copri or asnA-overexpressing E. coli, but not asnA-knockout S. copri, mitigated ammonia-induced CKD progression in mice. These findings highlight the role of gut microbial ammonia metabolism in CKD pathogenesis and underscore the therapeutic potential of microbial-based interventions.