Abstract P031: Endothelial Microparticles In Pediatric Obesity

Introduction: Endothelial activation represents one of the earliest signs of the atherosclerotic process. Microparticles (MPs) in plasma, particularly endothelial MPs (EMPs) are reproducible biomarkers of endothelial dysfunction with a simple blood draw. The goal of this study was to examine the association of obesity with MPs, EMPs (CD31+/CD41– and/or CD 144+/CD31–), and activated EMPs (CD106+). Hypothesis: We hypothesized that higher body mass index (BMI), body fat percent (BF%), and visceral adipose tissue (VAT) would be associated with higher levels of MPs, EMPs, and activated EMPs. Methods: This was a cross-sectional study of 280 children and adolescents ages 8-18 years old. Whole venous blood was collected and processed for platelet free-plasma (PFP) collection less than 3 hours after being drawn. PFP samples were prepared using serial centrifugations and then frozen as 100 μl aliquots at -80 ° C. MPs were measured using flow cytometry with size ranging from 0.3 to 1.0 μm. EMPs were defined as MP with CD31+/CD41– and/or CD 144+/CD31–. Active EMP was identified as EMP with CD 106+. BF% and VAT were measured using dual X-ray absorptiometry. Linear (total MPs and EMPs) and logistic (activated EMPs) regression models were used to examine the associations with adiposity group, BF%, and VAT, adjusting for Tanner stage, sex, and race. Results: The mean age of the cohort was 12.7 years, consisting of 147 females and BMI distribution: 112 normal-weight, 77 overweight/obesity, 91 severe obesity. Youth with overweight/obesity and severe obesity had higher numbers of total MPs (28,690 per μL PFP/g [-2,315, 59,695], p=0.07 and 52,744 per μL PFP/g [22,163, 83,324], p<0.001, respectively) and total EMPs (350 per μL PFP/g [81, 618], p=0.011 and 278 per μL PFP/g [13, 543], p=0.040, respectively) compared to peers with normal weight. In the entire cohort, higher BF% was associated with higher MPs (1,646 per μL PFP per percent [509, 2,783], p=0.005) and EMPs (11 per μL PFP per percent [2, 21], p=0.023), and higher VAT was associated with higher MPs (34 per μL PFP/g [11, 57], p=0.004) but not EMPs. Logistic regression analysis showed higher odds of active EMPs (odds ratio, 1.72 [1.0, 2.97], p=0.0502) in those with a BMI >85 th percentile compared to youth with a BMI <85 th percentile. In the entire cohort, BF% (odds ratio, 1.02 [1.00, 1.04], p=0.108) and VAT (odds ratio, 1.00 [1.00, 1.00], p=0.472) were not significantly associated with active EMPs. Conclusions: Higher levels of endothelial cell damage and activation were associated with obesity and excess adiposity in youth. The potential role of MPs and EMPs as useful biomarkers of cardiovascular disease risk merits further study.