E-cigarette use disrupts normal immune response to viral infections, particularly in women

This preliminary study investigated differences in immune response between non-smokers and people who use cigarettes or e-cigarettes by inoculating 47 participants with live attenuated influenza virus (LAIV) [1]. They found that at baseline, e-cigarette use disrupted normal immune response to viral infections, especially for women and girls.

Smoking e-cigarettes affects the body’s response to viral infection, but the effect of using e-cigarettes is different for females and males, and it is different from the effect of smoking regular cigarettes, according to new research. The presenter, Dr Meghan Rebuli (University of North Carolina at Chapel Hill, USA) explained the immune response in female e-cigarette users was “suggestive of immunosuppression” while in males it was “a mixture of immune gene upregulation and downregulation. Any dysregulation of immune responses to pathogens has the potential to increase susceptibility to infection or vaccines,” added Dr Rebuli. “Therefore, our data is suggestive that e-cigarette users, especially female e-cig users, may experience increased risk of infection.”

Dr Rebuli especially highlighted the surprising differences between immune responses in male and female e-cigarette users. “While we know that male and female immune systems function differently, especially in the context of respiratory virus infections, the opposing responses to virus in male and female e-cig users were striking,” said Dr Rebuli. “Specifically, as compared to normal non-smokers, 104 genes were downregulated in female e-cig users, the largest response being 23-fold downregulation, again suggestive of a state of immunosuppression. In contrast in male e-cig users, 10 immune genes were upregulated.”

The study included 47 participants, who were non-smokers, cigarette smokers, and e-cigarette users, based on self-reported use, smoking/vaping diaries, and nicotine- or tobacco-related biomarkers. Participants were inoculated with LAIV to gage the immune system response. Investigators collected epithelial lining fluid, nasal lavage fluid, nasal biopsies, and blood before and after inoculation with LAIV.

Investigators found that at baseline, cigarette smokers had increased influenza peptide cleavage activity compared with non-smokers. No difference was seen between non-smokers and e-cigarette users. However, certain genes and proteins necessary for immune system functioning were suppressed in e-cigarette users, but not in cigarette smokers, compared with non-smokers. Additionally, after LAIV was introduced, epithelial and nasal fluid samples showed that e-cigarette users had suppressed levels of interferon-gamma (IFNɣ) and IFNɣ-inducible chemokines.

E-cigarettes have not shown to reduce tobacco dependence. In the recent Special Eurobarometer 458 survey among people that have ever smoked (n=12,608), the use of e-cigarettes was associated with a lower rate of being a former smoker (adjusted odds ratio 0.43; 95% CI 0.32-0.58). Among current smokers, use of e-cigarettes was associated with more smoking (15.6 vs 14.4 cigarettes per day, P<0.05). A meta-analysis of 20 studies (including 15 cohort studies, 3 cross-sectional studies, and 2 clinical trials) indicated that the odds of smoking cessation in e-cigarette users was considerably lower (OR 0.72; 95% CI 0.57-0.91).

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   1. Rebuli ME, et al. A4170, ATS 2019, 17-22 May, Dallas, Texas, USA.

Posted on 23 July 20195 August 2021