Impact of Dietary Empagliflozin on Renal Cortex Metabolome and Lipidome in Mice.

Sodium glucose cotransporter, type 2 inhibitors (SGLT2i) have been demonstrated to be protective of kidney by unclear mechanisms. The aim of the current study was to determine how treatment with a common SGLT2i, Empagliflozin affected kidney cortical metabolome and lipidome in high-fat-fed, male TallyHo/Jng (TH) mice. TH mice are prone to obesity and insulin resistance progressing to type 2 diabetes (T2D). Adult mice (n = 7 or 8/group) were fed a control high-milk-fat diet (60% by weight) or this same diet supplemented with empagliflozin (0.01%) for 8-weeks, then euthanized and kidney cortex dissected and rapidly frozen. Metabolomics (targeted and untargeted) and lipidomics (targeted) were conducted on separate sections of cortex in our core facility by liquid chromatography-followed by tandem mass-spectroscopy. Data pre-processing included signal drift and inter-batch correction, as well as, removal of species with high coefficient of variability on pooled or reference analysis. Metabolites and lipids passing quality control (QC) included 207 and 467 unique species, respectively, which were further analyzed by MetaboAnalyst 5.0 and lipids, additionally by LipidSig, both publically available software platforms. Volcano plotting of metabolites and lipids revealed oppositely skewed patterns in that metabolites tended to be relatively decreased and lipid species increased with Empagliflozin. Seventy-four metabolites met our threshold of changed > 20% change and/or p < 0.05 and were analyzed for pathway enrichment. The top three pathways down regulated by Empagliflozin were urea cycle, spermine/spermidine biosynthesis, and aspartate metabolism. Analysis of metabolites of glycolysis/oxidative phosphorylation revealed a general 20-45% reduction in several species including phosphoenolpyruvate (PEP), succinate, and malic acid. In contrast, in general, several lipid species were increased with hierarchical clustering showing greatest effect on phosphatidylglycerol (16:1/16:1), 40% increase, p < 0.02, lysophosphatidylcholine (LPC, 20:4) 38% increase p < 0.03, and 10 additional phosphatidylcholine (PC) species. Overall, these analyses suggest a greater abundance of lipid, relative to carbohydrate and protein-based species, in the kidney cortex in response to chronic Empagliflozin treatment. It is unclear whether these differences are due to intracellular metabolic alterations or transport reduction in substrate (glucose and peptides) for metabolic pathways. In addition, we found no evidence of elevated gluconeogenesis with Empagliflozin observing a significant reduction in one key metabolite in this particular pathway, PEP. We may speculate oxidative phosphorylation and ATP generation is maintained relatively normal by greater oxidation of lipids (as opposed to proteins and carbohydrates) in the kidney proximal tubule of Empagliflozin-treated mice.