Abstract P082: Elevated Circulating Endothelial-Derived Microvesicles Are Associated With Obesity-Related Endothelial Dysfunction

Abstract

Background: Obesity reduces the number of years lived free of cardiovascular disease (CVD) and increases the number of years lived with CVD, contributing to increased morbidity and mortality risk across all ages. Experimental and clinical studies indicate that a proatherogenic endothelial phenotype is a major consequence of increased adiposity and a primary mechanism underlying obesity-related CVD. Extracellular microvesicles, particularly endothelial cell-derived microvesicles (EMVs), are seminal functional modulators of vascular health and disease. The purpose of this study was to determine: 1) if circulating EMV levels are elevated with obesity, independent of other cardiometabolic risk factors; and if so, 2) whether circulating EMVs are associated with obesity-related endothelial vasodilator dysfunction. Methods: Thirty sedentary, middle-aged adults (45-63 years) were studied: 15 normal weight (10M/5F; age: 56±1 yr; BMI: 23.2±0.4 kg/m2; body fat: 25.1±2.4 %) and 15 obese (10M/5F; age: 54±1 yr; BMI: 31.5±0.3 kg/m2; body fat: 37.2±1.7 %). All subjects were free of other cardiometabolic risk factors and overt disease. EMV identification (CD31 + /42b - ) and concentration in peripheral blood were determined by flow cytometry. Forearm blood flow (FBF: via plethysmography) was assessed in response to intra-arterial infusions of acetylcholine (4.0, 8.0 and 16.0 μg/100 mL tissue/min) and sodium nitroprusside (1.0, 2.0 and 4.0 μg/100 mL tissue/min). Results: Circulating EMV levels were ~100% higher (P<0.05) in obese (182±14 EMV/μL) compared with normal weight (91±12 EMV/μL) adults. FBF response to acetylcholine was significantly lower (~35%) in the obese (from 4.0±0.2 to 10.3±0.6 mL/100 mL tissue/min vs 4.3±0.3 to 15.4±0.8 mL/100 mL tissue/min) group. Circulating EMVs were significantly and inversely associated with total FBF response to acetylcholine (r=-0.55). Conclusions: Obesity, independent of other cardiometabolic risk factors, is associated with elevated circulating levels of EMVs. Higher circulating EMVs in obese adults may contribute to adiposity-related endothelial dysfunction and vascular disease risk. Indeed, circulating EMVs have been linked to disease risk, severity and outcome in other high-risk populations.