Ketogenic diet mitigates sepsis‑associated acute kidney injury in mice via reactivation of fatty acid oxidation: a multi‑omics and mechanistic study

Sepsis-associated acute kidney injury (SA-AKI) is a severe complication of sepsis characterized by impaired fatty acid oxidation (FAO) and lipid accumulation in renal tissues, contributing to high mortality and morbidity. This study investigated the protective effects and underlying mechanisms of a ketogenic diet (KD)—high-fat, adequate protein, and low-carbohydrate intake—in a mouse model of SA-AKI induced by lipopolysaccharide (LPS). Male C57BL/6 mice were randomized into control, SA-AKI, and KD-treated groups. Results demonstrated that KD significantly ameliorated renal dysfunction, as indicated by reduced serum creatinine (Scr), blood urea nitrogen (BUN), kidney injury molecule-1 (KIM-1), neutrophil gelatinase-associated lipocalin (NGAL), and pro-inflammatory cytokines including interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α). Histological analysis revealed preservation of renal tubular architecture and reduced lipid accumulation in KD-treated mice. Integrated multi-omics analyses—untargeted proteomics, targeted proteomics via parallel reaction monitoring (PRM), untargeted metabolomics, and untargeted lipidomics—identified significant metabolic remodeling associated with KD treatment. Proteomic analyses showed KD reversed SA-AKI-induced dysregulation of key FAO enzymes, notably acyl-CoA thioesterase 2 (ACOT2) and acyl-CoA thioesterase 4 (ACOT4). Metabolomics highlighted changes in FAO intermediates such as acylcarnitines, while lipidomics revealed normalization of triglycerides, diglycerides, and various phospholipids. Integrated correlation analysis confirmed robust interactions among proteins, metabolites, and lipid species linked to FAO. Mechanistically, KD restored renal adenosine triphosphate (ATP) levels and enhanced citrate synthase activity and FAO capacity. Additionally, KD treatment markedly upregulated mRNA and protein expressions of peroxisome proliferator-activated receptor alpha (PPARα), peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α), carnitine palmitoyltransferase 1A (CPT1A), carnitine palmitoyltransferase 2 (CPT2), and acyl-CoA oxidase 1 (ACOX1). Activation of the AMP-activated protein kinase (AMPK)–PGC1α–PPARα signaling pathway was further validated by Western blot and immunofluorescence analyses. These findings suggest that KD may mitigate SA-AKI by enhancing FAO and lipid homeostasis, supporting its potential as a therapeutic approach.