Endothelin-1-induced endothelial microvesicles impair endothelial cell function

The aim of this study was to determine the effects of endothelin-1 (ET-1)-generated endothelial microvesicles (EMVs) on endothelial cell inflammation, apoptosis, and endothelial nitric oxide synthase (eNOS). Human umbilical vein endothelial cells (HUVECs) were treated with ET-1 for 24 h. EMVs released into the supernatant from cells treated with ET-1 or vehicle were isolated and quantified. EMV release was higher (P < 0.05) in cells treated with ET-1 compared with control (95 +/- 15 vs. 54 +/- 5 EMV/mu L). Fresh HUVECs were then treated with either ET-1, ET-1-induced EMVs, or control EMVs for 24 h. ET-1-generated EMVs induced significantly higher release of IL-6 (181.0 +/- 16.0 vs. 132.1 +/- 8.1 pg/mL) and IL-8 (303.4 +/- 37.4 vs. 211.8 +/- 10.0 pg/mL), as well as greater total NF-kappa B p65 (76.0 +/- 7.6 vs. 57.1 +/- 2.1 AU) and active NF-kappa B p65 (Ser-536) (11.6 +/- 0.9 vs. 6.8 +/- 1.0 AU) expression than control EMVs. There were no significant differences in expression of caspase-9 (230.1 +/- 24.3 vs. 243.6 +/- 22.3 AU), caspase-3 (271.9 +/- 22.7 vs. 265.1 +/- 30.5 AU), and active caspase-3 (4.4 +/- 0.4 vs. 4.3 +/- 0.1 AU) in cells treated with ET-1-EMVs versus control EMVs. Total eNOS (108.4 +/- 11.4 vs. 158.8 +/- 1.6 AU) and activated eNOS (4.7 +/- 0.5 vs. 9.6 +/- 1.4 AU) were significantly lower in endothelial cells treated with ET-1-generated EMVs compared with control EMVs. The effects of ET-1-generated EMVs on cellular markers and mediators of endothelial inflammation, as well as eNOS function, was comparable to the effects of ET-1. In summary, ET-1 induces an EMV phenotype that adversely affects endothelial cell function. ET-1-generated EMVs may contribute to the atherogenic effect of ET-1. NEW & NOTEWORTHY Endothelin-1 (ET-1) is a potent vasoconstrictor peptide released by the endothelium that contributes to the regulation of vascular tone. Overexpression of ET-1 has been implicated in the etiology of atherosclerotic vascular disease. Endothelial cell-derived microvesicles (EMVs) play a pivotal role in vascular health and disease. Their functional phenotype is largely dictated by the stimulus for release. EMVs released in response to various pathological conditions have been shown to elicit deleterious vascular effects. In the present study, we determined, in vitro, the effect of ET-1 on EMV release from endothelial cells and the effects of ET-1-generated EMVs on endothelial cell inflammation, apoptosis, and endothelial nitric oxide synthase (eNOS). ET-1 induced a marked increase in EMV release. ET-1-generated EMVs significantly increased endothelial cell inflammation and reduced eNOS protein expression and activation. Moreover, the endothelial effects of ET-1-derived EMVs were similar to the direct effects of ET-1. ET-1-generated EMVs may contribute to the proatherogenic profile of ET-1.