Differential Gene Expression Using RNA Sequencing Profiling in a Reconstituted Airway Epithelium Exposed to Conventional Cigarette Smoke or Electronic Cigarette Aerosols

Abstract

The use of electronic cigarettes (e-cigarettes) potentially offers a safer alternative to conventional tobacco prod-ucts. The advance in molecular biology and computational sciences offers new perspective to assess adverse bi-ological responses for product risk assessment by combining omics screens with knowledge-based biological pathways. Our aim was to compare transcriptomic perturbations in MucilAirÔ, a commercially available lung epithelial tissue, after short repeated exposure to cigarette smoke (3R4F) and e-cigarette (Vype ePen) aero-sols. We performed deep RNA sequencing and secreted inflammatory cytokine profiling postexposure. One hun-dred twenty-three genes were differentially expressed at fold change (FC) >1.5 and p-false discovery rate (pFDR) <0.1 for 3R4F exposure and 0 genes for Vype ePen aerosol exposure. When a relaxed filter pFDR <0.5 and FC >1.5 was applied, 29 genes were identified with e-cigarette aerosol exposure and used for validation of potential candidates by quantitative reverse transcription polymerase chain reaction (qRT-PCR). Gene enrichment anal-ysis was conducted and predicted a response to 3R4F smoke exposure in biological processes involving inflam-mation and oxidative stress pathways. No enrichment could be performed for Vype ePen aerosol exposure due to the lack of regulated gene candidates at those exposure conditions even after qRT-PCR validation. Of a panel of 33 cytokines screened, 8 were upregulated (FC >1.5 p < 0.05) following 3R4F smoke exposure, which was in agreement with our enrichment analysis. In conclusion, aerosol from the tested e-cigarette caused limited per-turbations in gene and inflammatory cytokine expression compared to conventional cigarette smoke, as assessed using next-generation sequencing-based systems biology approaches in 3D commercially available reconstituted lung epithelial tissues.