Abstract 2069: Impact Of Endothelial Stiffening And CD36-mediated Lipid Uptake On Atherosclerotic Lesion Formation

Abstract

Objective: To determine the impact of endothelial stiffening induced by CD36 (cluster of differentiation 36) lipid uptake in the development of atherosclerosis. Approach and Results: Endothelial stiffening of intact en face monolayers, as assessed by atomic force microscopy, reveal the hyperlipidemic mouse model of atherosclerosis, LDLR -/- (low density lipoprotein receptor knockout) is significantly stiffer, especially in the atheroprone aortic arch, as compared to wild type controls (n=4 male mice with 8-15 tissue measurement sites per condition per mouse, p<0.05). Furthermore, a 4-5 month high fat diet (HFD) feeding in LDLR -/- mice resulted in significantly enhanced stiffening compared to regular chow feeding, an effect that was observed in males but not females (n=6-8 mice, p<0.05). There was a significantly greater plaque development, as analyzed using Oil O Red staining for lipids, in male HFD-fed LDLR -/- mice, as compared to age-matched females (n=5-6, p<0.05). No significant difference between males and females was found in lipid panel parameters (n=4-6) or weight gain (n=10-14). Specific downregulation of CD36 in male hypercholesterolemic Cdh5.CreERT2CD36fl/fl LDLR -/- mice led to both a significant decrease in endothelial stiffening (n=5 mice, p<0.05) and in the areas of atherosclerotic lesion formation (n=5-6 mice, p<0.05). Mechanistically, we show that the saturated fatty acid, palmitic acid, increased endothelial stiffening in the en face monolayers of wild type mice, an effect which is prevented by the pre-treatment of the CD36 irreversible inhibitor, SSO (sulfo-N-succinimidyl oleate, n=5-6 male mice, p<0.05). Conclusions: These results highlight that endothelial stiffness from intact aortas and atherosclerotic plaque formation following HFD feeding is strongly dependent on endothelial CD36.