E-cigarette use results in suppression of immune and inflammatory-response genes in nasal epithelial cells similar to cigarette smoke

Abstract

Exposure to cigarette smoke is known to result in impaired host defense responses and immune suppressive effects. However, the effects of new and emerging tobacco products, such as e-cigarettes, on the immune status of the respiratory epithelium are largely unknown. We conducted a clinical study collecting superficial nasal scrape biopsies, nasal lavage, urine, and serum from nonsmokers, cigarette smokers, and e-cigarette users and assessed them for changes in immune gene expression profiles. Smoking status was determined based on a smoking history and a 3- to 4-wk smoking diary and confirmed using serum cotinine and urine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) levels. Total RNA from nasal scrape biopsies was analyzed using the nCounter Human Immunology v2 Expression panel. Smoking cigarettes or vaping e-cigarettes resulted in decreased expression of immune-related genes. All genes with decreased expression in cigarette smokers (n = 53) were also decreased in e-cigarette smokers. Additionally, vaping e-cigarettes was associated with suppression of a large number of unique genes (n = 305). Furthermore, the e-cigarette users showed a greater suppression of genes common with those changed in cigarette smokers. This was particularly apparent for suppressed expression of transcription factors, such as EGR1, which was functionally associated with decreased expression of 5 target genes in cigarette smokers and 18 target genes in e-cigarette users. Taken together, these data indicate that vaping e-cigarettes is associated with decreased expression of a large number of immune-related genes, which are consistent with immune suppression at the level of the nasal mucosa.

Keywords: e-cigarettes; gene expression; nasal epithelial cells.

Fig. 1.

Correlation between serum cotinine and urine NNAL levels and cigarette/e-cigarette (E-cig) usage in smokers and e-cigarette users. Serum cotinine (A) and urine NNAL levels (B) from smokers were correlated with the average number of cigarettes smoked per day. Serum cotinine (C) and urine NNAL (D) from e-cigarette users were correlated with the average puffs per day. Pearson correlation coefficient and P values are depicted. NS, not significant.

Fig. 2.

Number of genes changed in cigarette smokers (CS) and e-cigarette (EC) users. A: total number of genes changed in smokers and e-cigarette users compared with nonsmokers. B: Venn diagram of the genes unique or common to cigarette smokers and e-cigarette users.

Fig. 3.

Comparison of fold change gene expression in cigarette smokers and e-cigarette users. The level of transcriptional changes in the 53 genes common to cigarette smokers and e-cigarette was compared and depicted as the relative fold change in this heatmap.

Fig. 4.

Functional transcription factor networks in cigarette smokers (A) and e-cigarette users (B).

Fig. 5.

Functional networks regulated by the transcription factor EGR1 in cigarette smokers (A) and e-cigarette users (B).

Fig. 6.

Comparison of fold change CSF-1 levels in cigarette smokers and e-cigarette users. Levels of CSF-1 were analyzed in NLF from cigarette smokers and e-cigarette users and normalized to the average level observed in nonsmokers. Data are expressed as mean ± SE fold change over nonsmokers. *Statistically different from nonsmokers, P < 0.05.