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E‐Cigarette Vapor Induces an Apoptotic Response in Human Gingival Epithelial Cells Through the Caspase‐3 Pathway

Electronic cigarettes represent an increasingly significant proportion of today's consumable tobacco products. E‐cigarettes contain several chemicals which may promote oral diseases. The aim of this study was to investigate the effect of e‐cigarette vapor on human gingival epithelial cells. Results show that e‐cigarette vapor altered the morphology of cells from small cuboidal form to large undefined shapes. Both single and multiple exposures to e‐cigarette vapor led to a bulky morphology with large faint nuclei and an enlarged cytoplasm. E‐cigarette vapor also increased L‐lactate dehydrogenase (LDH) activity in the targeted cells. This activity was greater with repeated exposures. Furthermore, e‐cigarette vapor increased apoptotic/necrotic epithelial cell percentages compared to that observed in the control. Epithelial cell apoptosis was confirmed by TUNEL assay showing that exposure to e‐cigarette vapor increased apoptotic cell numbers, particularly after two and three exposures. This negative effect involved the caspase‐3 pathway, the activity of which was greater with repeated exposure and which decreased following the use of caspase‐3 inhibitor. The adverse effects of e‐cigarette vapor on gingival epithelial cells may lead to dysregulated gingival cell function and result in oral disease. J. Cell. Physiol. 232: 1539–1547, 2017. © 2016 Wiley Periodicals, Inc.