Background
The kidney plays a central role in elimination of metabolic waste products and regulation of low-molecular weight metabolites via glomerular filtration, tubular secretion and reabsorption. Disruption of these processes
Conclusions
Advanced CKD in rats with adenine-induced chronic interstitial nephropathy results in profound changes in the serum metabolome, activation of inflammatory, oxidative and fibrotic pathways, and suppression of cytoprotective and antioxidant pathways.
Methods
Male Sprague-Dawley rats were randomized to the CKD and control groups ( n = 8/group). CKD was induced by administration of adenine (200 mg/kg body weight/day) by oral gavage for 3 weeks. The control group was treated with the vehicle alone. The animals were then observed for an additional 3 weeks, at which point they were sacrificed and kidney and serum samples were collected. Serum metabolomic and lipidomic analyses were performed using ultra-performance liquid chromatography-quadrupole time-of-flight high-definition mass spectrometry. Kidney tissues were processed for histological and molecular biochemical analyses.
Results
CKD rats exhibited increased plasma urea and creatinine concentrations, renal interstitial fibrosis, tubular damage and up-regulation of pro-inflammatory, pro-oxidant and pro-fibrotic pathways. Comparison of serum from CKD and control rats revealed significant differences in concentrations of amino acids and lipids including 33 metabolites and 35 lipid species. This was associated with marked abnormalities of fatty acid oxidation, and γ-linolenic acid and linoleic acid metabolism in CKD rats. Logistic regression analysis identified tetracosanoic acid, docosatrienoic acid, PC(18:3/14:1) and l -aspartic acid, tetracosanoic acid and docosatrienoic acid as novel biomarkers of chronic interstitial nephropathy. Conclusions: Advanced CKD in rats with adenine-induced chronic interstitial nephropathy results in profound changes in the serum metabolome, activation of inflammatory, oxidative and fibrotic pathways, and suppression of cytoprotective and antioxidant pathways.