title: Nicotine exposure induces bronchial epithelial cell apoptosis and senescence via ROS mediated autophagy-impairment.
abstract: Waterpipe smoking and e-cigarette vaping, the non-combustible sources of inhaled nicotine exposure are increasingly becoming popular and marketed as safer alternative to cigarette smoking. Hence, this study was designed to investigate the impact of inhaled nicotine exposure on disease causing COPD-emphysema mechanisms. For in vitro studies, human bronchial epithelial cells (Beas2b) were treated with waterpipe smoke extract (WPSE, 5%), nicotine (5mM), and/or cysteamine (250μM, an autophagy inducer and anti-oxidant drug), for 6hrs. We observed significantly (p<0.05) increased ubiquitinated protein-accumulation in the insoluble protein fractions of Beas2b cells treated with WPSE or nicotine that could be rescued by cysteamine treatment, suggesting aggresome-formation and autophagy-impairment. Moreover, our data also demonstrate that both WPSE and nicotine exposure significantly (p<0.05) elevates Ub-LC3β co-localization to aggresome-bodies while inducing Ub-p62 co-expression/accumulation, verifying autophagy-impairment. We also found that WPSE and nicotine exposure impacts Beas2b cell viability by significantly (p<0.05) inducing cellular apoptosis/senescence via ROS-activation, as it could be controlled by cysteamine, which is known to have an anti-oxidant property. For murine studies, C57BL/6 mice were administered with inhaled nicotine (intranasal, 500μg/mouse/day for 5 days), as an experimental model of non-combustible nicotine exposure. The inhaled nicotine exposure mediated oxidative-stress induces autophagy-impairment in the murine lungs as seen by significant (p<0.05, n=4) increase in the expression levels of nitrotyrosine protein-adduct (oxidative-stress marker, soluble-fraction) and Ub/p62/VCP (impaired-autophagy marker, insoluble-fraction). Overall, our data shows that nicotine, a common component of WPS, e-cigarette vapor and cigarette smoke, induces bronchial epithelial cell apoptosis and senescence via ROS mediated autophagy-impairment as a potential mechanism for COPD-emphysema pathogenesis.
authors.affiliation: College of Medicine, Central Michigan University, Mt Pleasant, MI, United States.
authors.forename: Manish
authors.initials: M
authors.lastname: Bodas
authors.affiliation: College of Medicine, Central Michigan University, Mt Pleasant, MI, United States.
authors.forename: Colin
authors.initials: C
authors.lastname: Van Westphal
authors.affiliation: College of Medicine, Central Michigan University, Mt Pleasant, MI, United States.
authors.forename: Rhett
authors.initials: R
authors.lastname: Carpenter-Thompson
authors.affiliation: Department of Chemistry and Biochemistry, Central Michigan University, Mt Pleasant, MI, United States.
authors.forename: Dillip
authors.initials: D
authors.lastname: K Mohanty
authors.affiliation: College of Medicine, Central Michigan University, Mt Pleasant, MI, United States; Department of Pediatrics and Pulmonary Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD, United States. Electronic address: neeraj.vij@cmich.edu.
authors.forename: Neeraj
authors.initials: N
authors.lastname: Vij
mesh_terms: D000818:Animals; D017209:Apoptosis; D001343:Autophagy; D001980:Bronchi / Q000473:pathology; D002460:Cell Line; D016922:Cellular Senescence; D003543:Cysteamine / Q000494:pharmacology; D065104:Cystine Depleting Agents / Q000494:pharmacology; D004847:Epithelial Cells / Q000187:drug effects / Q000502:physiology*; D008168:Lung / Q000187:drug effects / Q000473:pathology; D008810:Mice, Inbred C57BL; D009538:Nicotine / Q000633:toxicity*; D029424:Pulmonary Disease, Chronic Obstructive / Q000209:etiology / Q000473:pathology; D017382:Reactive Oxygen Species / Q000378:metabolism*; D000073867:Water Pipe Smoking / Q000009:adverse effects
chemical_list: D065104:Cystine Depleting Agents; D017382:Reactive Oxygen Species; D003543:Cysteamine; D009538:Nicotine
keywords: Anti-oxidant; Autophagy; Autophagy-impairment; COPD-emphysema; Hookah; Nicotine; Waterpipe; Waterpipe-smoke-extract (WPSE)