Exposure to Electronic Cigarettes Impairs Pulmonary Anti-Bacterial and Anti-Viral Defenses in a Mouse Model

Abstract

Electronic cigarettes (E-cigs) have experienced sharp increases in popularity over the past five years due to many factors, including aggressive marketing, increased restrictions on conventional cigarettes, and a perception that E-cigs are healthy alternatives to cigarettes. Despite this perception, studies on health effects in humans are extremely limited and in vivo animal models have not been generated. Presently, we determined that E-cig vapor contains 7x1011 free radicals per puff. To determine whether E-cig exposure impacts pulmonary responses in mice, we developed an inhalation chamber for E-cig exposure. Mice that were exposed to E-cig vapor contained serum cotinine concentrations that are comparable to human E-cig users. E-cig exposure for 2 weeks produced a significant increase in oxidative stress and moderate macrophage-mediated inflammation. Since, COPD patients are susceptible to bacterial and viral infections, we tested effects of E-cigs on immune response. Mice that were exposed to E-cig vapor showed significantly impaired pulmonary bacterial clearance, compared to air-exposed mice, following an intranasal infection with Streptococcus pneumonia. This defective bacterial clearance was partially due to reduced phagocytosis by alveolar macrophages from E-cig exposed mice. In response to Influenza A virus infection, E-cig exposed mice displayed increased lung viral titers and enhanced virus-induced illness and mortality. In summary, this study reports a murine model of E-cig exposure and demonstrates that E-cig exposure elicits impaired pulmonary anti-microbial defenses. Hence, E-cig exposure as an alternative to cigarette smoking must be rigorously tested in users for their effects on immune response and susceptibility to bacterial and viral infections.

Phagocytosis and Inflammation: Exploring the effects of the components of E-cigarette vapor on macrophages

“…2016) and mouse colonization with Streptococcus pneumoniae and influenza viral load (Sussan et al. 2015). …”

“…2015; Sussan et al. 2015). There have been no reports in the literature showing any changes for PG alone (as found in the present study), which we found very interesting given there is great discussion in vaping forums regarding the pros and cons of PG versus VG for taste and vapor production in various E‐cigarette generations, and the awareness that PG has already been shown to be a skin (Lessmann et al.…”

“…2014; Sussan et al. 2015). Many of these mouse studies suffer from varied or nonphysiological delivery methods, as well as often lacking a solid basis in in vitro studies, thus this study presents a thorough in vitro study designed to be a basis for future in vivo studies.…”

Acute effects of short term use of e-cigarettes on airways physiology and respiratory symptoms in smokers with and without airways obstructive diseases and in healthy non smokers

“…There is also an increasing number of studies in animal models implicating possible health effects. Namely, exposure to e-cigarette vaping results in immunomodulatory effects that are similar to those observed after exposure to conventional cigarette smoke, impairs pulmonary anti-bacterial and anti-viral defenses 12 , aggravates allergen-induced airway Inflammation and hyper-responsiveness 13 , induces toxicity, and oxidative stress. The aforementioned studies indicate that e-cigarette use might have significant consequences on the human respiratory system.…”

Use of Electronic Nicotine Delivery Systems Among Adolescents: Status of the Evidence and Public Health Recommendations

“…29,30 Animal models also suggest that ENDS vapor exposure stimulates oxidative stress and weakens pulmonary immune defenses against viral and bacterial infections. 31,32 However, animal model and in vitro assays do indicate that the toxicity associated with ENDS aerosol exposure is far less than that associated with combustible tobacco cigarettes.…”