JUUL e-liquid exposure elicits cytoplasmic Ca 2+ 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 Ca ²⁺ 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 Ca ²⁺ 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.
Competing Interests: Declaration of Competing Interest The authors report no declarations of interest.
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