Circulating Extracellular Microvesicles Associated with Electronic Cigarette Use Increase Endothelial Cell Inflammation and Reduce Nitric Oxide Production

The purpose of this study was to determine the effect of circulating microvesicles isolated from chronic electronic (e-)cigarette users on cultured human umbilical vein endothelial cell (HUVEC) expression of nuclear factor-kappa B (NF-kappa B), cellular cytokine release, phosphorylation of endothelial nitric oxide synthase (eNOS) and NO production. The HUVECs were treated with microvesicles isolated via flow cytometry from nine non-tobacco users (five male and four female; 22 +/- 2 years of age) and 10 e-cigarette users (six male and four female; 22 +/- 2 years of age). Microvesicles from e-cigarette users induced significantly greater release of interleukin-6 (183.4 +/- 23.6 vs. 150.6 +/- 15.4 pg/mL; P = 0.002) and interleukin-8 (160.0 +/- 31.6 vs. 129.4 +/- 11.2 pg/mL; P = 0.01), in addition to expression of p-NF-kappa B p65 (Ser536) (18.8 +/- 3.4 vs. 15.6 +/- 1.5 a.u.; P = 0.02) from HUVECs compared with microvesicles from non-tobacco users. Nuclear factor-kappa B p65 was not significantly different between microvesicles from the non-tobacco users and from the e-cigarette users (87.6 +/- 8.7 vs. 90.4 +/- 24.6 a.u.; P = 0.701). Neither total eNOS (71.4 +/- 21.8 vs. 80.4 +/- 24.5 a.u.; P = 0.413) nor p-eNOS (Thr495) (229.2 +/- 26.5 vs. 222.1 +/- 22.7 a.u.; P = 0.542) was significantly different between microvesicle-treated HUVECs from non-tobacco users and e-cigarette users. However, p-eNOS (Ser1177) (28.9 +/- 6.2 vs. 45.8 +/- 9.0 a.u.; P < 0.001) expression was significantly lower from e-cigarette users compared with non-tobacco users. Nitric oxide production was significantly lower (8.2 +/- 0.6 vs. 9.7 +/- 0.9 mu mol/L; P = 0.001) in HUVECs treated with microvesicles from e-cigarette users compared with microvesicles from non-tobacco users. This study demonstrated increased NF-kappa B activation and inflammatory cytokine production, in addition to diminished eNOS activity and NO production resulting from e-cigarette use.