Editor’s Choice, January 2019

Tom Ferkol, MD

Ghosh A, Coakley RC, Mascenik T, et al. Chronic e-cigarette exposure alters the human bronchial epithelial proteome. Am J Respir Crit Care Med. 2018;198:67-76.

Lured by deceptive marketing tactics and popular flavorings, electronic cigarettes have emerged as a threat to the health of children and adolescents. During the past decade, electronic cigarettes have rapidly risen in popularity among young people in many countries. In the United States (US), use of electronic cigarettes rose nearly 80% last year, with one-in-five high school students using these products regularly.

Even though the US National Academies of Sciences, Engineering, and Medicine found substantial evidence that exposure of potentially harmful ingredients from electronic cigarettes is lower than combustible cigarettes, it does not mean that electronic cigarette aerosols are “harmless”, contrary to industry claims. Several lines of evidence from in vitro and animal studies have revealed the deleterious effects of electronic cigarette vapors, showing that e-cigarette exposure causes inflammation, oxidative stress, and is toxic to pulmonary, endothelial, and stem cells in culture. However, remarkably few clinical studies have examined their effects on the human lung.

In this study, published last year in the American Journal of Respiratory Critical Care Medicine, Arunava Ghosh and colleagues from the University of North Carolina at Chapel Hill performed proteomic analyses of lavage samples collected from healthy non-smokers (n = 8), smokers (n = 9) and vapers (n = 9) who used the product for more than 6-months clearly showed that electronic cigarette vapors exert marked and extensive biological effects on human airways. Specifically, the authors found that 191 proteins were significantly up- or down-regulated in airway secretions from electronic cigarette users, in contrast to 292 altered proteins in smokers. A total of 113 proteins were uniquely changed in vapers, affecting fourteen pathways involved in mucin production, innate immunity, early endosomes and trafficking, macromolecular complexes, and mitochondria. Moreover, these effects were primarily mediated by the propylene glycol/vegetable glycerin base.

While long-term consequences are still unknown, vaping indisputably exerted extensive biological effects on human airways, leading the authors to conclude that “inhalation of e-cigarette vapor is not without consequences and by no means innocuous, and they should not be prescribed as a safe or harmless tobacco alternative.”