Circulating Extracellular Vesicles in Electronic Cigarette Users Adversely Affect Cerebral Endothelial Nitric Oxide and Endothelin-1 Production

Abstract

The use of electronic cigarettes (e-cigarettes) continues to increase, particularly among adolescents and young adults. Although initially promoted as a healthier alternative to tobacco smoking, there is increasing evidence (both experimental and clinical) that e-cigarette use can adversely affect cardiovascular and cerebrovascular function. For example, chronic e-cigarette use has been linked with neurovascular impairment likely stemming from endothelial cell dysfunction. Circulating endothelial cell-derived microvesicles (EMVs) are now recognized as both a biomarker and mediator of vascular health and disease. Indeed, EMVs have been shown to be involved in the pathogenesis of cerebrovascular dysfunction leading to increased stroke risk. Circulating EMVs are elevated in users of e-cigarettes; whether e-cigarette associated EMVs promote endothelial abnormalities known underlying cerebrovascular dysfunction and increase stroke risk is unknown. The experimental aim of this study was to determine the effect of EMVs isolated from e-cigarette users on brain endothelial cell nitric oxide (NO) and endothelin (ET)-1 production. Circulating EMVs (CD31+/42b-) were isolated (flow cytometry) from 20 young adults (age:18-25 yr): 9 non-smokers/e-cigarette users (5M/4F; age 21±1 yr; BMI: 25.2±1.1 kg/m2) and 11 e-cigarette users (7M/4F; 22±1 yr; 23.9±0.9 kg/m2). Human cerebral microvascular endothelial cells (hCMECs) were cultured and separately treated with EMVs from each subject. Circulating EMV concentrations were significantly higher in the e-cigarette users vs non-smokers (199±13 vs 64±5 EMV/μL). Phosphorylation is the primary posttranslational modification regulating eNOS enzyme activity. Phosphorylation of Ser1177 confers the greatest activation of eNOS; whereas, phosphorylation at Thr495 reduces eNOS activation. Expression of p-eNOS (Ser1177) was lower (7.7±0.6 vs 9.8±0.5 AU; P<0.05) and p-eNOS (Thr495) higher (28.6±1.3 vs 24.3±1.5 AU; P<0.05) in cells treated with EMVs from e-cigarette users vs non-smokers. Concordantly, NO production was ~25% lower (5.5±0.3 vs 7.2±0.5 μmol/L; P<0.05) in cells treated with EMVs from e-cigarette users. e-cigarette-associated EMVs also significantly increased (~20-55%) the expression of Big ET-1 (40.9±2.1 vs 26.4±1.9 AU) and endothelin converting enzyme (43.9±1.5 vs 35.8±1.7 AU) as well as ET-1 production (33.2±0.8 vs 28.7±0.6 pg/mL) in hCMECs. In summary, EMVs harvested from e-cigarette users reduced endothelial nitric oxide synthase (eNOS) activation and NO production and increased ET-1 synthesis and release in brain endothelial cells in vitro. Potential adverse neurovascular effects of chronic e-cigarette use may be mediated by circulating EMVs. Nothing to disclose This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.