JUUL e-liquid exposure elicits cytoplasmic Ca2+ responses and leads to cytotoxicity in cultured airway epithelial cells

Rationale: The popularity of new and emerging tobacco products such as E-cigarettes (E-cigs) is rapidly expanding worldwide. However, uncertainties surrounding the potential health consequences due to the use of such products exist and warrant further study. Methods: Cultured A549 and Calu-3 airway epithelia were exposed to three out of the eight types of JUUL brand e-liquids (Mint, Virginia Tobacco and Menthol, all containing 3% nicotine at 1% and 3% (vol/vol) dilutions) and assessed for viability using a resazurin-based assay. Intracellular Ca2+ levels were measured using fluorescent indicators and pro-inflammatory cytokine levels were monitored by quantitative PCR (qPCR). Cultures were also analyzed by flow cytometry to evaluate apoptotic markers and cell viability. Results: Exposing the airway epithelial cells to the flavored JUUL e-liquids led to significant cytotoxicity, with the Mint flavor being the overall most cytotoxic. The Mint flavored e-liquid also led to significant elevations in intracellular Ca2+ and upregulation of the pro-inflammatory cytokine IL-6 and early apoptotic marker Annexin V. Conclusions: JUUL e-liquid challenge resulted in a loss of airway epithelial cell viability, induced pro-inflammatory responses and eventually caused apoptosis. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

Exposure to flavored JUUL e-liquids may result in loss of airway epithelial cell viability, induction of pro-inflammatory responses, and eventual apoptosis.