Electronic cigarettes

Electronic cigarettes (e-cigarettes) have gained their popularity as a substitute for cigarettes or cigars. Despite the widespread use of flavoring chemicals in e-cigarettes, the health impacts of the flavoring compounds, in particular their effects on critical cellular function in the lung, remain largely unknown. The goal of this study was to identify transcriptomic changes and impacted biological pathways in primary human bronchial epithelial cells (HBECs) exposed to flavoring chemicals (diacetyl or 2,3-pentanedione) and to flavored e-cigarette smoke. An airway-liquid interface culturing method was used to differentiate primary human bronchial epithelial cells (HBECs) into mature epithelial cells, which were then treated with 25 ppm diacetyl, 100 ppm 2,3 pentanedione, or e-cigarette smoke solution containing 2 ppm diacetyl. Poly(A)-selected RNA-Seq libraries were prepared with the PrepX RNA-Seq for Illumina Library kit. An Illumina HiSeq 2500 instrument was used to generate 50 base pair single-end reads. STAR was used to align sequencing reads to the hg38 reference genome, and HTSeq was used to quantify transcript levels. DESeq2 was used to perform differential expression analysis. Transcriptome profiles obtained via RNA-Seq for normal human bronchial epithelium cells (3-donor pool) treated in duplicate with 25 ppm diacetyl, 100 ppm 2,3 pentanedione, e-cigarette smoke solution containing 2 ppm diacetylor, or vehicle control for 24 hours were obtained to measure the effects of exposure to e-cigarette smoke and its flavoring chemicals.