Disturbed flow disrupts eNOS and caveolin‐1 expression and colocalization via glycocalyx degradation

Abstract

Atherosclerosis is the main cause of cardiovascular diseases such as coronary artery and carotid artery disease and is known to occur in specific, atheroprone areas of the vasculature characterized by disturbed flow patterns. The endothelial glycocalyx, a mechanotransductive carbohydrate layer that lines the endothelium, helps maintain vascular homeostasis through flow‐induced regulation of vasculoprotective molecules such as nitric oxide. Areas of atherosclerosis development have been shown to contain diminished glycocalyx expression; however, it is unclear whether glycocalyx degradation contributes to atherosclerosis or is a result of its progression. Here, we investigated the effects of disturbed flow on glycocalyx‐mediated nitric oxide regulation in rat fat pad endothelial cells, which robustly express glycocalyx components. Using a custom parallel‐plate flow chamber, we found that disturbed flow (DF) patterns characteristic of atheroprone regions of the vasculature decrease glycocalyx coverage and thickness in comparison to uniform flow (UF). This decrease was accompanied by a reduction in endothelial nitric oxide synthase (eNOS) expression. For the first time, we discovered that DF also decreased the expression of caveolin‐1 (cav‐1), a core protein of caveolae microvesicles that assist in eNOS activation. Additionally, fluorescence microscopy also demonstrated decreased cav‐1 membrane and upstream distribution as well as decreased eNOS‐cav‐1 colocalization in areas of disturbed flow. Finally, UF exposure upon enzymatic degradation of heparan sulfate, a major glycocalyx component, resulted in DF‐like expression colocalization of eNOS and cav‐1, implicating the glycocalyx in eNOS and cav‐1 regulation. These findings provide new evidence to the body of information on glycocalyx‐mediated endothelial regulation, which collectively suggests that glycocalyx degradation may contribute to atherosclerosis development.Support or Funding InformationThis study was funded by National Institute of Health Grant K01 HL125499, National Science Foundation Grant DGE 1451070, Northeastern University Provost Start‐up funds, and an Engineering Dean's Fellowship provided by Northeastern University.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.