E-cigarette use is increasing rapidly in the United States, especially amongst youth, underscoring the vital need to improve understanding of its health risks. Relevant data could inform policy, guide public health and clinical intervention efforts, and inform individuals who might use or who are using this product. This research will significantly enhance the understanding of the possible health effects of e-cigarette use by relating the acute and long-term use of e-cigarettes and conventional cigarettes ("products") to well-validated cardiovascular and pulmonary disease biomarkers. 3 different "use-groups" of participants will be enrolled: exclusive e-cigarette users (n=165), exclusive cigarette smokers (n=165), and a "control" group of never-users (n=110). These groups reflect the primary decisions that people can make regarding their future tobacco use: to continue to smoke cigarettes, to switch to e-cigarettes, or to avoid tobacco use entirely. It is essential that smokers and health care providers have accurate information on the health effect of these choices.
\[Additionally, 100 participants will be invited to be part of an epigenetics sub-study (50 E-cig users, 25 smokers and 25 controls), prior to smoking, an additional 16 ml of blood will be collected in Vacutainer cell separation tubes for peripheral blood monocyte (PBMC) Isolation containing sodium citrate.\]
Product use will be related to well-validated biomarkers that sensitively and reproducibly reflect mechanisms, injury, and/or future risk related to cardiovascular or pulmonary disease. Biomarkers will be related to: 1) acute product use in the laboratory (exposure challenges), 2) lifetime history of product use, and/or 3) real-time measures of product use in participants' daily lives. The primary cardiovascular biomarkers are brachial artery flow-mediated dilation (a measure of endothelial function) and carotid intima-media thickness, a measure of subclinical arterial injury and atherosclerosis. The primary pulmonary disease biomarkers will be measures of lung volumes and flow rates (Forced Expiatory Volume exhaled in the first second (FEV1), Forced vital capacity (FVC), FEV1/FVC) obtained by spirometry. Treadmill exercise stress testing will be performed (to assess aerobic fitness), electrocardiography (to measure heart rate variability, HRV), and measure heart rate, blood pressure, lipids, HgbA1c, and inflammation/oxidation markers (leukocyte count, C-reactive protein, urinary F2 isoprostanes and exhaled nitric oxide). This research will show how product use-groups differ in response to acute product use and long-term use as they are related to key cardiovascular and pulmonary biomarkers. Objective measures of product use include exhaled CO and plasma nicotine/cotinine and urinary nicotine/cotinine concentrations. History of product use within use-groups will be related to biomarker status.
The proposed research will yield vital and comprehensive data regarding product use, subclinical arterial injury, atherosclerosis burden, arterial and pulmonary function, cardiac and aerobic fitness, cardiac autonomic regulation, systemic and pulmonary inflammation, and oxidative stress, as well as other key outcomes. These data will serve as a foundation for future longitudinal investigations of e-cigarette health effects and will inform public policy decisions, clinical intervention, and patient guidance regarding e-cigarettes.
