Sweroside attenuates heart failure with preserved ejection fraction via targeting PCSK9-CD36 interaction to reduce cardiac-hepatic lipotoxicity

BACKGROUND Heart failure with preserved ejection fraction (HFpEF) is characterized by cardiac and hepatic lipotoxicity, necessitating effective therapeutic strategies. Sweroside, a natural compound with significant pharmacological activity, is widely investigated in pharmacological studies of cardiovascular and fatty liver diseases. However, its effects and mechanisms against HFpEF remain unclear. OBJECTIVE To investigate the effects of sweroside on cardiac function and cardiac/hepatic lipotoxicity in HFpEF mice, and to explore the underlying molecular mechanisms and targets. METHODS An HFpEF mouse model was established using a high-fat diet and l-NAME. Echocardiography, lipidomics, Masson staining, and Oil Red O staining were employed to assess the cardioprotective effects of sweroside, including the reduction of inflammation and inhibition of cardiac and hepatic lipid deposition in HFpEF mice. The effects of sweroside on lipotoxicity and inflammation induced by palmitic acid (PA) and oleic acid (OA) in H9c2, AC16, AML12, and HepG2 cells were investigated using immunofluorescence, flow cytometry, and Oil Red O staining. Western blot, co-immunoprecipitation, molecular docking, SPR, and LC-MS/MS were used to identify the direct binding of sweroside to CD36 and its impact on the PCSK9-CD36 complex. Finally, the regulatory role of sweroside on CD36 was confirmed using CD36-siRNA-transfected H9c2 cardiac cells and CD36-KO HepG2 cells. RESULTS Sweroside significantly improved cardiac function and inhibited cardiac lipid deposition in HFpEF mice. Lipidomics results indicated that the improvement in cardiac function by sweroside was associated with the inhibition of inflammation and regulation of mitochondrial function. Consequently, sweroside significantly reduced the mitochondrial aggregation of the NLRP3 inflammasome in cardiac tissue, thereby suppressing the levels of IL-1β and IL-18. In both HFpEF mice and PA+OA-stimulated H9c2 and AC16 cardiac cell models, the ability of sweroside to inhibit lipid deposition, reduce NLRP3 inflammasome activation, and improve myocardial mitochondrial oxidative phosphorylation was potentially related to the downregulation of CD36. Furthermore, sweroside exerted a positive effect on hepatic lipid deposition in HFpEF mice. Similar effects were observed in PA+OA-stimulated AML12 and HepG2 cells, and this action was found to depend on the formation of the PCSK9-CD36 complex. Through methods including molecular docking, SPR, and LC-MS/MS, CD36 was identified as a potential direct binding target of sweroside. In CD36-siRNA-transfected H9c2 cardiac cells and CD36-KO HepG2 cells, the ability of sweroside to alleviate lipid deposition and inflammation was inhibited. CONCLUSION This study reveals the pharmacological mechanism by which sweroside, by targeting the PCSK9-CD36 complex, inhibits the mitochondrial accumulation of the myocardial NLRP3 inflammasome, reduces inflammatory responses, reverses the hepatic lipid deposition phenotype, and improves cardiac function in HFpEF mice. Collectively, these findings provide a solid experimental basis for the development of anti-HFpEF therapeutics.