Abstract

Acute kidney injury (AKI) superimposed on diabetic nephropathy (DN) accelerates fibrosis progression to end-stage renal disease, but the underlying mechanisms remain poorly understood. Since gut microbiota and their metabolites are pivotal contributors to diabetic pathogenesis and fibrotic development, we examined the role of gut microbiota-derived metabolites in the regulation of fibrosis following AKI-on-DN. Using a murine model of folic acid-induced AKI in diabetic nephropathy, we revealed that folic acid injury exacerbated kidney dysfunction and fibrosis, which was associated with macrophage to myofibroblast transition (MMT). Integrative multi-omics profiling identified dysbiosis of intestinal flora as a critical pathological amplifier. Fecal microbiota transplantation blunted MMT and attenuated kidney fibrosis in diabetic kidney mice following folic acid stress. Furthermore, Metabolomic profiling identified a robust decline of gut microbiota-derived eicosapentaenoic acid (EPA) in AKI-on-DN mice, paralleled by reduced EPA levels in both serum and feces. EPA supplementation substantially impeded MMT and alleviated kidney fibrosis in AKI-on-DN mice. Notably, macrophage depletion considerably diminished MMT and collagen deposition in injured kidneys of AKI-on-DN mice. Collectively, our findings demonstrate that EPA plays a crucial role in regulating macrophage to myofibroblast transformation, thereby driving kidney fibrosis following AKI superimposed on diabetic nephropathy.