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/6 F; 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 vs. 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 adults with obesity (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.NEW & NOTEWORTHY Despite an improved understanding of many of the pathological consequences associated with human obesity, factors that initiate, promote, and accelerate cerebrovascular events are not completely understood. This study provides novel data demonstrating that circulating EEVs from adults with obesity adversely affect eNOS activity, reducing nitric oxide bioavailability, enhancing ET-1 production, and impairing t-PA release in brain microvascular endothelial cells in vitro. These changes in endothelial cell phenotype have been linked with cerebrovascular dysfunction and ischemic stroke risk.