Gut microbiota-derived indole-3-acetic acid ameliorates calcium oxalate renal stone formation via AHR/NF‑κB axis

The exact mechanism of calcium oxalate stone (CaOx) formation is not fully understood. Evidence suggests that disruptions in the gut microbiota and its metabolites influence kidney stone formation. We conducted microbiome-metabolome analysis to pinpoint microbial metabolites linked to kidney stones in both patient and healthy control groups. We explored the impact of these kidney stone-related microbial metabolites on CaOx-induced stones, along with their underlying mechanisms of action. We exposed NRK-52E cells to CaOx crystals that had been pretreated with indole-3-acetic acid. Rats, induced to develop CaOx stones via ethylene glycol and ammonium chloride administration, were also treated with IAA. Our investigations encompassed assessments of Ca²⁺ levels, reactive oxygen species levels, markers of oxidative stress, apoptosis levels, inflammation levels, and gene expression within AHR/NF‑κB pathway, both in cellular and tissue samples.Indole-3-acetic acid showed significantly reduction in patients with renal stones. The administration of IAA has been found to alleviate the deposition and adhesion of calcium oxide stones in the kidneys. Furthermore, IAA demonstrates beneficial effects on kidney damage and inflammation. IAA efficiently reduces intracellular levels of ROS, osteopontin, and CD44 in NRK-52E cells exposed to CaOx as well as in a rat model of stone formation. Mechanistically, IAA inhibits the activation of the NF-κB signaling pathway through the elevation of AHR in kidney stones. Our research has uncovered a novel connection between gut microbiota-derived tryptophan metabolites and kidney stones. The microbial metabolite IAA/AHR/NF-κB pathway may be a promising target for kidney stone treatment.