Abstract 048: Extracellular Endothelial Microvesicles Causative Agents In Hypertension-related Endothelial Dysfunction

Abstract

We have previously demonstrated that endothelial cell-derived microvesicles (EMVs) are elevated with hypertension and are associated with endothelial dysfunction. However, it is unknown whether EMVs play a causative role in blood pressure-related endothelial dysfunction. The experimental aim of this study was to determine the effects of EMVs isolated from hypertensive adults on endothelial cell inflammation, apoptosis and nitric oxide (NO) production. Twenty middle-aged adults were studied: 10 normotensive (NT: 8M/2F; 57 + 2 yr; BP: 113/71 + 2/2 mmHg; EMVs: 64 + 10 EMV/μL) and 10 hypertensive (HT: 6M/4F; 56 + 2 yr; 137/82 + 2/2 mmHg; 115 + 17 EMV/μL). All subjects were sedentary, non-smokers, non-medicated and free of overt cardiometabolic diseases. EMVs (CD144+) were identified, sorted and collected from plasma by flow cytometry. Human umbilical vein endothelial cells were cultured and treated with EMVs from either NT or HT adults. EMVs from HT induced significantly greater release of interleukin (IL)-6 (38.9±1.5 vs 31.5±0.9 pg/mL) and IL-8 (38.1±2.7 vs 30.3±1.8 pg/mL) compared with EMVs from NT. Concordantly, HT-related EMVs induced ~25% higher (P<0.05) expression of phosphorylated-NF-kB p65 (Ser536; active NF-kB) (168.5 + 12.1 vs 136.8 + 7.0 AU). HT EMVs induced significantly higher activation of the apoptotic proteins p38-MAPK (26.0 + 4.5 vs 12.4 + 1.2 AU) and caspase-3 (243.1±36.7 vs 150.8±17.0 AU) than NT EMVs. Although total eNOS expression was not significantly altered; active eNOS (pSer1177) (221.02 + 34.8 vs 331.5 + 30.4 AU) and, in turn, NO production (6.2 + 0.4 vs 9.4 + 0.6 υmol/L) were significantly lower (~30%) in the cells treated with EMVs from HT adults. Increased inflammation, apoptosis susceptibility and decreased NO production are central features of endothelial dysfunction. Circulating EMVs represent both a biomarker and mediator of endothelial dysfunction with hypertension.