Endothelial CD36 mediates diet-induced increases in aortic stiffness

Abstract

A Western diet (WD) contributes to the rising prevalence of obesity and insulin resistance, both of which are key risk factors for arterial stiffening and related cardiovascular diseases. We recently found that elevated CD36 is associated with increased ectopic lipid accumulation, systemic and tissue insulin resistance, and arterial stiffening. Here, we further examined whether endothelial cell (EC) specific CD36 (ECCD36) participates in WD-induced aortic insulin resistance, lipid accumulation, inflammation, fibrosis, remodeling, and associated aortic stiffening. Female ECCD36 knockout (ECCD36^−/−) and wild-type (ECCD36^+/+) mice, at six weeks of age, were fed either a Western diet (WD) or a standard chow diet (CD) for 16 weeks. Aortic stiffness and activity were investigated by ultrasound (pulse wave velocity) and wire myography, respectively. Gene expression was monitored by western blot and quantitative PCR. Lipid content and aortic remodeling were explored by Oil red O staining and immunostaining, respectively. 16 weeks of WD increased aortic stiffening that was associated with vascular insulin resistance and reduced insulin metabolic signaling via phosphoinositide 3-kinases/protein kinase B. The pathophysiological changes in vascular insulin resistance and stiffening were associated with activation of mammalian target of rapamycin/S6 kinase signaling, increased lipid disorders, decreased tight junction-associated protein occludin, and increased proinflammatory response, and aortic remodeling. These abnormalities were blunted in ECCD36^−/− mice fed a WD. These findings suggest that under an obesogenic Western diet (WD), heightened ECCD36 signaling contributes to aortic insulin resistance, increased lipid accumulation, increased endothelial permeability and proinflammatory responses, fibrosis, vascular remodeling, and consequent aortic stiffening.