Obesity-Related Circulating Endothelial Extracellular Vesicles Negatively Affect Cerebral Microvascular Cell Function

The aim of this study was to determine, in vitro, the effect of endothelial cell-derived extracellular vesicles (EEVs) from adults with obesity on brain microvascular endothelial cell nitric oxide (NO) and endothelin (ET)-1 production as well as tissue-type plasminogen activator (t-PA) release. Circulating EEVs (CD144+ extracellular vesicles) were identified, enumerated and isolated (flow cytometry) from 24 midlife and older sedentary adults (45-71 yr): 12 normal weight (6 M/6 F; body mass index (BMI) ≥18.5 and ≤25 kg/m2) adults and 12 adults with obesity (6 M/6F; BMI ≥30.0 kg/m2). Human cerebral microvascular endothelial cells (hCMECs) were cultured and treated with EEVs from either normal weight adults or adults with obesity. Expression of phosphorylated (p)-eNOS (Ser1177) was ~20% lower (31.5+5.6 v s 39.1+7.9 AU) and p-eNOS (Thr495) expression ~40% higher (47.3+13.2 vs 33.4+10.5 AU) in hCMECs treated with EEVs from obese compared with normal weight adults. As a result, NO production was significantly lower (~20%) in hCMECs treated with EEVs from obese adults (4.9+0.4 vs 5.9+0.5 µmol/L). Cell expression of Big ET-1 (317.8+51.8 vs 241.6+65.0 AU) and endothelin converting enzyme (838.3+160.8 vs 631.8+126.3 AU) as well as ET-1 production (21.9+1.6 vs 18.0+3.9 pg/mL) were significantly higher in hCMECs treated with EEVs from adults with obesity. t-PA release in response to thrombin was significantly lower in hCMECs treated with EEVs from obese (from 49.3+6.6 to 52.3+8.2 pg/mL) compared with normal weight (from 52.3+8.8 to 62.0+8.1 pg/mL) adults. Circulating EEVs are a potential mediator of obesity-related cerebrovascular dysfunction and stroke risk.