Empagliflozin Improves Endothelial And Cardiomyocyte Function In Human Heart Failure With Preserved Ejection Fraction Via Reduced Pro-Inflammatory-Oxidative Pathways And Protein Kinase G Alpha Oxidation

Aims Sodium-glucose-cotransporter-2 inhibitors showed favourable cardiovascular outcomes, but the underlying mechanisms are still elusive. This study investigated the mechanisms of empagliflozin in human and murine heart failure with preserved ejection fraction (HFpEF).Methods and results The acute mechanisms of empagliflozin were investigated in human myocardium from patients with HFpEF and murine ZDF obese rats, which were treated in vivo. As shown with immunoblots and ELISA, empagliflozin significantly suppressed increased levels of ICAM-1, VCAM-1, TNF-alpha, and IL-6 in human and murine HFpEF myocardium and attenuated pathological oxidative parameters (H2O2, 3-nitrotyrosine, GSH, lipid peroxide) in both cardiomyocyte cytosol and mitochondria in addition to improved endothelial vasorelaxation. In HFpEF, we found higher oxidative stress-dependent activation of eNOS leading to PKGI alpha oxidation. Interestingly, immunofluorescence imaging and electron microscopy revealed that oxidized PKG1 alpha in HFpEF appeared as dimers/polymers localized to the outermembrane of the cardiomyocyte. Empagliflozin reduced oxidative stress/eNOS-dependent PKGI alpha oxidation and polymerization resulting in a higher fraction of PKGI alpha monomers, which translocated back to the cytosol. Consequently, diminished NO levels, sGC activity, cGMP concentration, and PKGI alpha activity in HFpEF increased upon empagliflozin leading to improved phosphorylation of myofilament proteins. In skinned HFpEF cardiomyocytes, empagliflozin improved cardiomyocyte stiffness in an anti-oxidative/PKGI alpha-dependent manner. Monovariate linear regression analysis confirmed the correlation of oxidative stress and PKGI alpha polymerization with increased cardiomyocyte stiffness and diastolic dysfunction of the HFpEF patients.Conclusion Empagliflozin reduces inflammatory and oxidative stress in HFpEF and thereby improves the NO-sGC-cGMP-cascade and PKGI alpha activity via reduced PKGI alpha oxidation and polymerization leading to less pathological cardiomyocyte stiffness.