Fig. 8.

3 Days of e-cig aerosol exposure under sub-ohm conditions (0.15 Ω & 4.8 V) revealed that cinnamon flavor is more cytotoxic and causes oxidative damage to a greater extent than butter flavored-e-cig aerosol. H292 cells were exposed to either butter- or cinnamon-flavored e-cig aerosol at the air–liquid interface (ALI) for 3 days. a Numbers of viable cells were significantly decreased by both butter- and cinnamon-flavored e-cig aerosols compared to respective air controls. b Levels of extracellular lactate dehydrogenase (LDH) were significantly increased by both butter- and cinnamon-flavored e-cig aerosols compared to respective air controls. c Levels of extracellular reactive oxygen species (ROS) were significantly increased by both butter- and cinnamon-flavored e-cig aerosols compared to their respective air controls. d The extracellular protein concentration of 8-OHdG was significantly increased by the cinnamon-flavored e-cig aerosol compared to the air control group. This ELISA was analyzed for cell inserts (n = 3 per group), and each cell insert was further evaluated in duplicate. e Levels of extracellular nitric oxide (NO) were significantly decreased by both butter- and cinnamon-flavored e-cig aerosols compared to respective air controls. For assays (a, b, c, e), data are from one experiment representative of results from three independent experiments, each performed in triplicate (n = 3 per group). For each cell insert, bioassays were further evaluated in duplicate or triplicate. For all assays (b–e) data were normalized to cell count and are presented as mean ± SEM. Comparisons between e-cig group and respective air control group were made by the student t-test; *p < 0.05: significantly different from respective air control. f Heatmap of the dysregulated genes by the e-cig aerosol exposures. Data are from H292 cells from distinct experiments. Data are presented as fold-change over the respective air-control group (n = 3 per group, each sample run in duplicate). Fold-changes > ± 1.5 were considered significant.Results from other independent experiments are represented in Additional file 1: Figures S6 to S9