SGLT2 Inhibition Alters the Hepatic and Circulating Metabolome of Mice Under a High-Milk-Fat Diet

Abstract

Recent studies have shown that the inhibition of Sodium-glucose cotransporter 2 (SGLT2), which reabsorbs glucose in the renal proximal tubule, can aid in glycemic control under conditions of type 2 diabetes (T2D). Though it acts directly on the kidney, these inhibitors also lead to great improvement in liver function. Previously, we challenged TallyHo mice, an inbred polygenetic mice model that recapitulates T2D, with a high milk fat diet (HMFD) for 12 weeks in the continued absence or presence of Empagliflozin (EMPA), an FDA-approved SGLT2 inhibitor. Male mice showed a decrease in circulating triglycerides, hyperglycemia, and hepatic lipid and cholesterol esters (Kurtz et al 2022). However, the mechanisms that underlie this improved liver phenotype is unknown. Thus, we sought to characterize the hepatic and circulating metabolic and lipidomic profiles that are altered and/or restored in the presence of EMPA using targeted and untargeted LC-MS. Control, HMFD, and HMFD + EMPA liver tissues and plasma samples were dissolved in a methanol/water 50/50 extraction buffer that contained debrisoquine (DBQ) for the positive mode standard and 4-nitrobenzoic acid for the negative mode standard. For the untargeted liver and plasma samples, a UPLC-QTOF analysis was performed. MetaboAnalyst was used to quantify metabolite changes with inclusion criteria set to a fold change of 2 and a p-value <0.05. Of note, previous studies have shown that EMPA promotes the upregulation of ketone bodies including β-Hydroxybutyrate (BHB). We noted a similar upregulation of BHB in our metabolomic analysis and confirmed that EMPA led to a ~1.5-fold increase (p < 0.022) in this circulating ketone body. In addition, of those metabolites that met the inclusion criteria, we identified 12 that were downregulated and 9 that were upregulated +EMPA in the male samples. Out of these, orotate, sarcosine, tartrate, and dihydrofolate levels were restored to those of control levels. In the female samples, 6 were downregulated and 3 were upregulated +EMPA. Indoxyl sulfate, butylcarnitine, and valerylcarnetine were all restored to control levels. Of particular interest is the finding that EMPA treatment restores levels of key metabolites that are involved in the folate and pyrimidine biosynthesis pathways. Previous studies have determined that folate deficiency can promote insulin resistance and the urea cycle, a pathway that is integrated with pyrimidine biosynthesis, is upregulated under conditions of T2D and non-alcoholic fatty liver disease. Future studies are aimed at identifying the role of EMPA's hepatic protection in these metabolic pathways. NIDDK This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.