Abstract 4368248: Endothelial ILK deficiency promotes cardiac dysfunction via pro-inflammatory extracellular vesicle signaling.

Introduction: Endothelial function is crucial for maintaining vascular homeostasis. Integrin-linked kinase (ILK) has emerged as a key regulator of endothelial homeostasis, preventing endothelial dysfunction by stabilizing eNOS activity and counteracting inflammation. However, the mechanisms by which ILK loss contributes to vascular pathology remain poorly understood. Hypothesis: This study tested the hypothesis that extracellular vesicles (EVs) secreted by ILK deficient endothelium serve as mediators of coronary endothelial activation leading to cardiac dysfunction. Methods: We investigated the role of endothelial ILK in microvascular damage and endothelial activation via extracellular vesicles (EV) using an endothelial-specific ILK knockout mouse model (ecILK-cKO) and ILK deleted mouse endothelial cells. Results: Endothelial ILK deletion led to sustained inflammation in vivo as revealed by CD68+ infiltration and ICAM and VCAM coronary endothelial expression as early as one week after deletion which increased three weeks after ecILK deletion. Endothelial cell-ILK deletion led to endothelial activation, marked by increased expression of endothelial activation markers (iNOS and ICAM), NF-kB signaling, macrophage adhesion to the endothelium and the release of proinflammatory EV. EVs derived from ILK-deficient endothelial cells impaired endothelial function in vitro, decreasing proliferation and migration, and disrupting the angiogenic processes. Moreover, circulating EV from ecILK-cKO mice (cEVecILK-cKO) induce endothelial cell activation and vascular inflammation when administered to healthy mice. Prolonged exposure to cEVecILK-cKO resulted in progressive cardiac dysfunction, characterized by reduced ejection fraction, increased fibrosis, and microvascular remodeling mimicking the phenotype of th ecILKcKO mice. Conclussions: These results identify ILK as a critical suppressor of endothelial inflammation and highlight EV as key mediators of endothelial crosstalk in cardiovascular pathology. Targeting ILK-dependent EV signaling could offer novel therapeutic strategies for preventing microvascular damage and cardiac remodeling in ischemic heart disease and heart failure. Keywords: extracellular vesicles; Integrin-linked kinase; endothelial cell activation; inflammation; cardiac dysfunction; microvascular remodeling.