Obesity and diabetes related disturbances in systemic metabolism induce a cardiometabolic heart failure with preserved ejection fraction phenotype in a combined high-fat, high sucrose diet and streptozotocin mouse model
BackgroundDiabetes and obesity are associated with an increased incidence of heart failure with preserved ejection fraction (HFpEF), but the underlying pathophysiological mechanisms are poorly understood. A shortage of appropriate preclinical mouse models reflecting different pathophysiological disease aspects might contribute to this inadequate understanding of the complex and diverse HFpEF pathophysiology. We conducted a comprehensive analysis of a non-genetic, inducible T2DM mouse model with regard to its suitability as a preclinical model of cardiometabolic, diabetes-induced HFpEF. MethodsT2DM was induced in C57Bl/6 mice by high-fat/high-sucrose diet (HFHSD) combined with low-dose streptozotocin (STZ) treatment (DIO-STZ), control animals received standard chow (chow). As additional control groups, animals of a DIO group were solely fed HFHSD throughout the study, and a STZ group received solely STZ injections while maintained on a standard chow. Cardiac function was assessed in vivo by echocardiography and left ventricular catheterization, as well as in vitro using the isolated perfused heart model. Structural, molecular and bioenergetic disturbances were analyzed by immunohistochemistry, RNA-seq, qPCR, western blot, and extracellular flux analysis of myocardial tissue, among others. ResultsBlood glucose, fatty acids and ketone body levels were elevated, and insulin plasma level were reduced in DIO-STZ animals compared to chow. DIO-STZ mice showed a strong cardiometabolic HFpEF phenotype with reduced cardiac output, end-diastolic volume, and increased filling pressure. Neither STZ nor DIO mice showed signs of HFpEF development. No difference in myocardial fibrosis nor in in vitro myocardial stiffness was detected between DIO-STZ and chow. Myocardial RNA-Seq clearly pointed towards disturbances in lipid and ketone metabolism. Extracellular flux analysis in intact cardiac tissue slices revealed an increased fatty acid oxidation capacity without differences in glucose metabolism. Mitochondrial respirometry revealed no indication of general mitochondrial dysfunction or mitochondrial uncoupling, but a reduced capacity for {beta}-hydroxybutyrate oxidation. ConclusionsThe diabetic DIO-STZ mouse model showed a pronounced functional HFpEF phenotype. However, we show clear evidence that the underlying mechanism differs remarkably from the other HFpEF models making the DIO-STZ model a relevant extension of the range of HFpEF mouse models, especially for investigating molecular mechanisms or therapeutical interventions in diabetes associated HFpEF.