Gene Expression alterations in the Bronchial Epithelium of e-Cigarette Users.

Introduction:
This text provides an analysis of the effects of electronic cigarettes (ECIGs) on airway gene expression, specifically in the bronchial airway epithelium. The study compares the transcriptome-wide impact of ECIGs and tobacco cigarettes (TCIGs) in the bronchial airway epithelium and investigates the gene-expression effects of ECIG use in former smokers. The study's goal is to better understand the relationship between ECIG use and TCIG use in terms of their impact on airway gene expression.

Key Points:

* The study recruited current TCIG smokers, former TCIG smokers using ECIGs, and former TCIG smokers who underwent voluntary bronchoscopy.
* Bronchial epithelial cells were collected for RNa isolation, and microarray data acquisition was performed using affymetrix human Gene 1.0 ST arrays.
* Differential expression analysis via aNCOVa identified 3,165 genes whose expression varied between the three study groups, with 468 genes altered in ECIG users relative to former smokers.
* Genes downregulated in ECIG users are enriched among the genes most downregulated by exposure of airway epithelium to ECIG vapor in vitro.
* ECIGs induce both distinct and shared patterns of gene expression relative to TCIGs in the bronchial airway epithelium.
* The concordance of the genes altered in ECIG users and in the in vitro study suggests that genes altered in ECIG users are likely to be changed as the direct effect of ECIG exposure.
* Despite the increased use of ECIGs, their safety profile remains controversial, with the health risks likely lying somewhere between TCIG smoking and nonsmoking.

Main Message:
The study suggests that ECIGs induce both distinct and shared patterns of gene expression relative to TCIGs in the bronchial airway epithelium. The concordance of the genes altered in ECIG users and in the in vitro study suggests that genes altered in ECIG users are likely to be changed as the direct effect of ECIG exposure. however, further study is required to identify the clinical significance of these findings and to fully evaluate the pulmonary effect of ECIG exposure. The safety profile of ECIGs remains controversial, with the health risks likely lying somewhere between TCIG smoking and nonsmoking.

Corbett SE, Nitzberg M, Moses E, et al. Gene Expression alterations in the Bronchial Epithelium of e-Cigarette Users. Chest. 2019;156(4):764-773. doi:10.1016/j.chest.2019.05.022