Obesity is increasing in prevalence and is strongly associated with metabolic and cardiovascular disorders. The renin-angiotensin system (RAS) has emerged as a key pathogenic mechanism for these disorders; angiotensin (Ang)-converting enzyme 2 (ACE2) negatively regulates RAS by metabolizing Ang II into Ang 1-7. We studied the role of ACE2 in obesity-mediated cardiac dysfunction. ACE2 null (ACE2KO) and wild-type (WT) mice were fed a high-fat diet (HFD) or a control diet and studied at 6 months of age. Loss of ACE2 resulted in decreased weight gain but increased glucose intolerance, epicardial adipose tissue (EAT) inflammation, and polarization of macrophages into a proinflammatory phenotype in response to HFD. Similarly, human EAT in patients with obesity and heart failure displayed a proinflammatory macrophage phenotype. Exacerbated EAT inflammation in ACE2KO-HFD mice was associated with decreased myocardial adiponectin, decreased phosphorylation of AMPK, increased cardiac steatosis and lipotoxicity, and myocardial insulin resistance, which worsened heart function. Ang 1-7 (24 µg/kg/h) administered to ACE2KO-HFD mice resulted in ameliorated EAT inflammation and reduced cardiac steatosis and lipotoxicity, resulting in normalization of heart failure. In conclusion, ACE2 plays a novel role in heart disease associated with obesity wherein ACE2 negatively regulates obesity-induced EAT inflammation and cardiac insulin resistance.

Background: Although empagliflozin was shown to profoundly reduce cardiovascular events in diabetic patients and blunt the decline in cardiac function in nondiabetic mice with established heart failure (HF), the mechanism of action remains unknown. Methods and Results: We treated 2 rodent models of HF with 10 mg/kg per day empagliflozin and measured activation of the NLRP3 (nucleotide-binding domain-like receptor protein 3) inflammasome in the heart. We show for the first time that beneficial effects of empagliflozin in HF with reduced ejection fraction (HF with reduced ejection fraction [HFrEF]; n=30–34) occur in the absence of changes in circulating ketone bodies, cardiac ketone oxidation, or increased cardiac ATP production. Of note, empagliflozin attenuated activation of the NLRP3 inflammasome and expression of associated markers of sterile inflammation in hearts from mice with HFrEF, implicating reduced cardiac inflammation as a mechanism of empagliflozin that contributes to sustained function in HFrEF in the absence of diabetes mellitus. In addition, we validate that the beneficial cardiac effects of empagliflozin in HF with preserved ejection fraction (HFpEF; n=9–10) are similarly associated with reduced activation of the NLRP3 inflammasome. Lastly, the ability of empagliflozin to reduce inflammation was completely blunted by a calcium (Ca ²⁺ ) ionophore, suggesting that empagliflozin exerts its benefit upon restoring optimal cytoplasmic Ca ²⁺ levels in the heart. Conclusions: These data provide evidence that the beneficial cardiac effects of empagliflozin are associated with reduced cardiac inflammation via blunting activation of the NLRP3 inflammasome in a Ca ²⁺ -dependent manner and hence may be beneficial in treating HF even in the absence of diabetes mellitus.

This study sought to determine whether the sodium/glucose cotransporter 2 (SGLT2) inhibitor empagliflozin improved heart failure (HF) outcomes in nondiabetic mice. The EMPA-REG OUTCOME (Empagliflozin, Cardiovascular Outcome Event Trial in Type 2 Diabetes Mellitus Patients) trial demonstrated that empagliflozin markedly prevented HF and cardiovascular death in subjects with diabetes. However, despite ongoing clinical trials in HF patients without type 2 diabetes, there are no objective and translational data to support an effect of SGLT2 inhibitors on cardiac structure and function, particularly in the absence of diabetes and in the setting of established HF. Male C57Bl/6 mice were subjected to either sham or transverse aortic constriction surgery to induce HF. Following surgery, mice that progressed to HF received either vehicle or empagliflozin for 2 weeks. Cardiac function was then assessed in vivo using echocardiography and ex vivo using isolated working hearts. Although vehicle-treated HF mice experienced a progressive worsening of cardiac function over the 2-week treatment period, this decline was blunted in empagliflozin-treated HF mice. Treatment allocation to empagliflozin resulted in an improvement in cardiac systolic function, with no significant changes in cardiac remodeling or diastolic dysfunction. Moreover, isolated hearts from HF mice treated with empagliflozin displayed significantly improved ex vivo cardiac function compared to those in vehicle-treated controls. Empagliflozin treatment of nondiabetic mice with established HF blunts the decline in cardiac function both in vivo and ex vivo, independent of diabetes. These data provide important basic and translational clues to support the evaluation of SGLT2 inhibitors as a treatment strategy in a broad range of patients with established HF.