About this Research Topic
Millions of people use e-cigarettes nowadays. However, their long-term health effects are unknown. On one hand, they may help people quit conventional tobacco smoking and reduce the risk of developing chronic diseases, including cardiovascular disease, chronic obstructive lung disease and several types of cancer. Alternatively, they may not be as safe as previously thought and may contribute to the development of diseases associated with tobacco smoking and/or other diseases. Thus, the impact of e-cigarette use at the population level needs to be urgently assessed.
The scope and pervasive nature of the vaping epidemic is evident from the reports that a high number of youth and school-going children regularly use electronic cigarettes (“e-cigarettes”), and many are dual users who vape in addition to smoking traditional cigarettes. The e-cigarette electronically heats a mixture of nicotine, flavors and other constituents in propylene glycol and vegetable glycerin (i.e. the e-liquid) to generate aerosolized e-cigarette vapor. The three main ingredients of e-liquid are a mixture of the humectants propylene glycol and/or vegetable glycerin, flavoring chemicals, and nicotine in varying concentrations (ranging from 0—50 mg/ml). The safety of these ingredients when they are heated and inhaled by humans is not determined.
The scientific observations so far indicate wide-ranging effects of e-cigarette vapor exposure on bacteria and host. Chronic exposure to e-cigarettes has been shown to induce COPD-like changes marked by not only increased inflammation and mucus production, but also the suppression of innate immune responses and increased susceptibility to influenza virus infection. In humans, vaping has been reported to cause atypical pneumonia marked by the presence of lipid-laden macrophages in broncho-alveolar lavage. In vitro studies have shown that common flavoring chemicals found in cinnamon-, vanilla-, banana-, and almond-flavored e-liquids impair ciliary beat frequency and immune cell function (neutrophil oxidative burst) in a nicotine-independent manner. On the bacterial side, exposure is shown to induce virulence gene expression and biofilm formation by methicillin-resistant Staphylococcus aureus.
Given its exploding popularity and the recent reports of severe respiratory disease and deaths associated with vaping, it will be highly relevant both from academic and clinical sense to understand how the physiology of host (immune defenses) and of bacterial colonizers of the mucosal microbiome, as well as the composition of the microbiome, may respond to the exposure to e-cigarette vapor.
This Research Topic is aimed at improving our understanding of the effects of vaping on the human host and microbial colonizers. We welcome Original Research articles and Reviews related, but not limited, to the following topics:
• Effects of vaping on the virulence of microbial colonizers of respiratory or gut microbiota.
• Effects of vaping on microbiomes: including microbiomes in the respiratory and gastrointestinal systems, as well as those that may be present in e-liquids themselves. These studies can include microbiome profiling from subjects exposed to e-cigarette vapors relative to unexposed subjects. Studies from mice and humans examining effects of vaping on respiratory or other microbiota will be of interest.
• Effects of vaping on the host: both cellular and in vivo studies to better understand the impact of vaping on lung immune function and chronic inflammation.
• Effects of vaping on innate and acquired immunity: are e-cigarette users more susceptible to infection?
Keywords: vaping, microbiome, immunity
Important Note: All contributions to this Research Topic must be within the scope of the section and journal to which they are submitted, as defined in their mission statements. Frontiers reserves the right to guide an out-of-scope manuscript to a more suitable section or journal at any stage of peer review.