Heterophyllin B alleviates diabetes-induced myocardial injury by regulating MAVS-mediated mitochondrial homeostasis

Diabetic cardiomyopathy (DCM), a major cause of diabetic mortality, lacks effective therapies. This study investigated the cardioprotective role of Heterophyllin B (HET-B), a natural compound and its underlying mechanisms in DCM. Using streptozotocin-induced DCM mice and high glucose (HG)-treated H9C2/neonatal cardiomyocytes, we assessed cardiac function, mitochondrial homeostasis, and apoptosis. HET-B significantly improved cardiac function, indicated by increased ejection fraction (EF) and fractional shortening (FS). It also reduced cardiomyocyte apoptosis (in vivo/vitro), and ameliorated HG-induced mitochondrial damage, characterized by dysfunction, fragmentation, and excessive reactive oxygen species (ROS) production. HET-B enhanced mitochondrial fusion protein OPA1 expression and reduced Bax/Bcl2, cytochrome C (Cyt C) release and caspase-3 cleavage. Molecular docking and cellular thermal shift assays identified mitochondrial antiviral-signaling protein (MAVS) as a potential target of HET-B. HET-B reversed MAVS downregulation induced by HG/DCM in vitro and in vivo. Importantly, MAVS knockdown via siRNA abolished HET-B's protection against HG-induced apoptosis and mitochondrial damage. Furthermore, HET-B restored HG-impaired autophagic flux, reducing autolysosome accumulation and normalizing LC3-II. Collectively, the natural compound HET-B alleviates diabetic myocardial injury by targeting MAVS to enhance autophagy, maintain mitochondrial homeostasis, and inhibit cardiomyocyte apoptosis, positioning it as a promising therapeutic candidate for DCM.