Endothelial ANGPT2 impairs cardiomyocyte calcium homeostasis via ITGB3 receptor in murine sepsis-related cardiomyopathy

Sepsis-related cardiomyopathy (SCM) is a life-threatening complication of sepsis, characterized by cardiac dysfunction. Although angiopoietin 2 (ANGPT2) is pivotal in the pathological progress of several diseases, its functional involvement in the pathogenesis of SCM remains uncharacterized. In this study, we demonstrated that ANGPT2 is a key regulator of SCM progression, bridging the functional homeostasis between vascular endothelial cells (ECs) and cardiomyocytes. Bioinformatics analysis of a SCM-related gene set derived from public databases revealed that ANGPT2 is a critical regulatory node. Serum ANGPT2 levels correlated with elevated creatine kinase-MB (CK-MB) and cardiac troponin I (cTnI) in vivo. Abnormal cardiac function was observed in cecal ligation and puncture (CLP)-induced sepsis mouse model and adeno-associated virus 9-mediated endothelial cell-specific ANGPT2-overexpressing (AAV9-Angpt2) mice, primarily characterized by reduced left ventricular end-diastolic volume (LVEDV) and left ventricular end-systolic volume (LVESV). Additionally, integrin β1 (ITGB1) and integrin β3 (ITGB3) were upregulated, along with dysregulation of calcium signaling-associated proteins in cardiac tissue. Notably, AAV9-Angpt2 mice exhibited exacerbated CLP-induced cardiac dysfunction. In vitro experiments showed that ANGPT2 significantly reduced the beating frequency of primary neonatal mouse cardiomyocytes (NMCMs), and disrupted intracellular calcium homeostasis in adult mouse cardiomyocytes (AMCMs). Mechanistically, ANGPT2 activates and binds to the extracellular domains of ITGB3, thereby triggering ryanodine receptor 2 (RYR2) phosphorylation and upregulating the reticulum calcium ATPase 2 (ATP2a2) and phospholamban (PLN) expression, while simultaneously suppressing PLN phosphorylation. ITGB3-specific siRNA significantly attenuated the effects of ANGPT2 on calcium signaling proteins and intracellular calcium homeostasis. Collectively, these results suggest that the ANGPT2-ITGB3 signaling axis plays an important role in the pathogenesis of SCM in mice and may support this pathway as a potential therapeutic target during sepsis in humans.