Abstract Tu0057: Unveiling Dab2's Role and Mechanism in Endothelial Protection and Atheroma Regression

Introduction: Cardiovascular diseases are often associated with impaired responses from the endothelium. Endothelial cell dysfunction causes recruitment of immune and inflammatory cells to the intima, which initiate atheromatous plaque build-up. Transitioning from a stable to vulnerable atheroma fuels myocardial infarction and stroke, posing enormous health challenges. A novel and indispensable role for an endocytic adaptor protein called Disabled homolog 2 (Dab2) showed potential atheroprotective role, yet the molecular mechanisms and signaling pathways that direct Dab2 to combat arterial inflammation are completely unknown. Hypothesis: Dab2 safeguards endothelium function by curbing inflammation, preventing dysfunction, and restraining atheroma progression. Aims: To determine the role of Dab2 in protecting against endothelial dysfunction and to determine the therapeutic gain of Dab2 targeted delivery to the dysfunctional endothelium. Methods: We created endothelial-specific inducible Dab2 knockout mice (EC-Dab2iKO) and bred with ApoE-null background (EC-Dab2iKO/ApoE -/- ). We used western diet to build atherosclerosis mice model. RNA-seq was used to determine pathway changes. We also employed an innovative nanotechnology to deliver Dab2 mRNA. Results: Dab2 was downregulated in endothelium of human and mice aortic plaque. Western diet-fed EC-Dab2iKO/ApoE -/- mice exhibited heightened arterial inflammation and more severe plaque formation, with increased macrophage infiltration and reduced plaque stability in plaque. RNA-seq showed Dab2 depletion significantly increased pro-inflammatory markers and shear stress-related and atherosclerotic pathways. Dab2 protected against endothelial dysfunction by increasing pulsatile shear-dependent eNOS activation via promoting endosomal PI3K-Akt activation. To ensure the clinical relevance of our work, we employed an innovative atheroma-targeting nanoparticles with Lyp-1 peptide, to deliver Dab2 mRNA to the atherogenic endothelium to restore Dab2 function. This nanoparticles increased Dab2 expression in endothelial cell in vitro and restrained plaque progression in ApoE -/- mice. Conclusion: Dab2 protects against endothelial dysfunction during atheroma progression and is a downstream target gene of atheroprotective flow. The innovative targeting reagents will facilitate paradigm-shifting endeavor to provide a foundation for the development of new treatments to benefit patients at-risk for heart attacks and strokes.