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

• Published in: Toxicology letters Vol. 337; pp. 46 - 56
• Main Authors: Zhang, Rui, Jones, Myles M., Dornsife, Ronna E., Wu, Tongde, Sivaraman, Vijay, Tarran, Robert, Onyenwoke, Rob U.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.02.2021
• Subjects: Airway epithelial cells; Apoptosis; Calcium (Ca2+) signaling; Electronic cigarettes; Pro-inflammatory cytokines; Quantitative PCR (qPCR); Pro-inflammatory cytokines; Quantitative PCR (qPCR); Airway epithelial cells; Calcium (Ca2+) signaling; Electronic cigarettes; Apoptosis
• ISSN: 0378-4274; 1879-3169
• DOI: 10.1016/j.toxlet.2020.11.017

[Display omitted] •JUUL e-liquids exhibit cytotoxicity when used to challenge cultured airway epithelial cells.•Exposure to JUUL “Mint” flavored e-liquid led to significant elevations in cytoplasmic Ca2+.•Upregulation of the cytokine IL-6 and early apoptotic marker Annexin V was evident after the “Mint” e-liquid challenge. 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. 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. 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. JUUL e-liquid challenge resulted in a loss of airway epithelial cell viability, induced pro-inflammatory responses and eventually caused apoptosis.