Targeting Integrin β3 in Endothelial Cells Attenuates Cardiac Fibrosis Through the Calcium‐Calmodulin–Dependent Protein Kinase IIα– cAMP‐Responsive Element Binding Protein 1 Signaling Axis in Pressure Overload–Induced Heart Failure

BACKGROUND: Endothelial-to-mesenchymal transition (EndMT) is a key contributor to cardiac fibrosis, yet the role and underlying mechanisms of endothelial integrin β3 (ITGB3) activation in EndMT remain poorly understood. This study aims to explore the involvement of a novel ITGB3- CaMKIIα (calcium-calmodulin-dependent protein kinase IIα)-CREB1 (cAMP-responsive element binding protein) signaling axis in EndMT and to demonstrate that targeting endothelial ITGB3 mitigates pressure overload-induced heart failure (HF) by reducing cardiac fibrosis. METHODS: Endothelial-cell-specific ITGB3 knockout mice were subjected to transverse aortic constriction to induce HF. Cardiac function, and the expression of EndMT-associated genes were assessed to evaluate changes in cardiac remodeling. RNA sequencing and primary human endothelial cells and mouse cardiac microvascular endothelial cells were used to investigate downstream mechanisms. Additionally, the ITGB3-specific inhibitor RGDfK was applied in the treatment of HF. RESULTS: The activation of ITGB3 was predominantly observed within endothelial cells. Endothelial cell-specific ITGB3 deletion attenuated cardiac dysfunction. Mechanistically, ITGB3 knockdown and CaMKII inhibition reduced CaMKII activation and subsequently lowered nuclear CREB1 phosphorylation levels. Reciprocally, the genetic overexpression of ITGB3 in endothelial cells increased EndMT by activating the CaMKIIα-CREB1 axis. These results were further substantiated by pharmacological studies with the ITGB3 specific cyclic-RGD (Arg-Gly-Asp) peptide inhibitor (RGDfK). RGDfK treatment ameliorated pressure overload-induced cardiac remodeling and markedly improved cardiac function, establishing the disease-specific role of ITGB3 in vivo. CONCLUSIONS: This study demonstrates that endothelial ITGB3 regulates EndMT and contributes to the progression of pressure overload-induced HF, partly through the CaMKIIα-CREB1 signaling pathway. Targeting ITGB3 to inhibit EndMT may offer a promising therapeutic strategy for HF.