Differential responses to e-cig generated aerosols from humectants and different forms of nicotine in epithelial cells from nonsmokers and smokers.

Introduction:
This article presents a study on the effects of electronic cigarette (e-cig) generated aerosols on human nasal epithelial cells (hNECs) from nonsmokers and smokers. The study compares mucin and immune mediator responses to e-cig generated aerosols from propylene glycol (PG) and glycerol (GLY) with and without freebase nicotine or nicotine salt. The objective is to understand the differential responses of hNECs from nonsmokers and smokers to e-cig aerosols.

Key Points:

* The study used hNECs from nonsmokers and smokers and exposed them to e-cig generated aerosols from PG, GLY, and a 55:45 (vol/vol) PG:GLY mixture without nicotine.
* The study also exposed hNECs to e-cig generated aerosol from PG:GLY at a 55:45 (vol/vol) ratio with 12 mg/mL of freebase nicotine or with 12 mg/mL of nicotine salt.
* The study measured mucin levels in the apical wash of exposed hNECs and cytokine levels in the basolateral supernatant of exposed cells.
* The study found that e-cig generated aerosols from GLY and PG:GLY significantly increased MUC5aC levels in the apical wash of exposed hNECs from nonsmokers but not in hNECs from smokers.
* The study also found that e-cig generated aerosol from GLY increased cytokine levels of IL-10, IL-15, and IL-1 b in hNECs from both nonsmokers and smokers. however, the e-cig generated aerosol from GLY only increased IL-2, IL-6, IL-8, IP-10, and VEGF in hNECs from smokers.
* The study also exposed hNECs to e-cig generated PG:GLY with freebase nicotine or nicotine salt, which caused immensely different mucin and cytokine secretions from hNECs.
* The study found no significant increases in LDh release with any of the e-cig generated aerosol from exposures as compared to the air control.

Main Message:
The study highlights the differential responses of hNECs from nonsmokers and smokers to e-cig generated aerosols. The study found that e-cig generated aerosols from GLY and PG:GLY significantly increased MUC5aC levels in the apical wash of exposed hNECs from nonsmokers but not in hNECs from smokers. The study also found that e-cig generated aerosol from GLY increased cytokine levels of IL-10, IL-15, and IL-1 b in hNECs from both nonsmokers and smokers. however, the e-cig generated aerosol from GLY only increased IL-2, IL-6, IL-8, IP-10, and VEGF in hNECs from smokers. The study also found that e-cig generated PG:GLY with freebase nicotine or nicotine salt caused immensely different mucin and cytokine secretions from hNECs. Therefore, the study suggests that the effects of e-cig aerosols on hNECs depend on the type of humectant and nicotine used and that these effects may differ between nonsmokers and smokers. These findings have important implications for the regulation of e-cigarettes and their potential health effects.

Escobar YNh, Morrison CB, Chen Y, et al. Differential responses to e-cig generated aerosols from humectants and different forms of nicotine in epithelial cells from nonsmokers and smokers. american journal of physiology Lung cellular and molecular physiology. 2021;320(6):L1064-L1073. doi:10.1152/ajplung.00525.2020