Cigarette-smoke (CS) exposure and aging are the leading causes of chronic obstructive pulmonary disease (COPD)-emphysema development, although the molecular mechanism that mediates disease pathogenesis remains poorly understood. Our objective was to investigate the impact of CS exposure and aging on autophagy and the pathophysiological changes associated with lung aging (senescence) and emphysema progression. Beas2b cells, C57BL/6 mice, and human (GOLD 0-IV) lung tissues were used to determine the central mechanism involved in CS/age-related COPD-emphysema pathogenesis. Beas2b cells and murine lungs exposed to cigarette smoke extract (CSE)/CS showed a significant ( P< 0.05) accumulation of poly-ubiquitinated proteins and impaired autophagy marker, p62, in aggresome bodies. Moreover, treatment with the autophagy-inducing antioxidant drug cysteamine significantly ( P < 0.001) decreased CSE/CS-induced aggresome bodies. We also found a significant ( P < 0.001) increase in levels of aggresome bodies in the lungs of smokers and COPD subjects in comparison to nonsmoker controls. Furthermore, the presence and levels of aggresome bodies statistically correlated with severity of emphysema and alveolar senescence. In addition to CS exposure, lungs from old mice also showed accumulation of aggresome bodies, suggesting this as a common mechanism to initiate cellular senescence and emphysema. Additionally, Beas2b cells and murine lungs exposed to CSE/CS showed cellular apoptosis and senescence, which were both controlled by cysteamine treatment. In parallel, we evaluated the impact of CS on pulmonary exacerbation, using mice exposed to CS and/or infected with Pseudomonas aeruginosa ( Pa), and confirmed cysteamine's potential as an autophagy-inducing antibacterial drug, based on its ability to control CS-induced pulmonary exacerbation ( Pa-bacterial counts) and resulting inflammation. CS induced autophagy impairment accelerates lung aging and COPD-emphysema exacerbations and pathogenesis.

No abstract

Aims: Electronic cigarettes (e-cigarettes) are proposed to be a safer alternative to tobacco cigarettes. Hence, we evaluated if e-cigarette vapors (eCV) impair cellular proteostasis similar to cigarette smoke exposure. Results: First, we evaluated the impact of eCV exposure (2.5 or 7.5 mg) on Beas2b cells that showed significant increase in accumulation of total polyubiquitinated proteins (Ub, insoluble fractions) with time-dependent decrease in proteasomal activities from 1 h ( p < 0.05), 3 h ( p < 0.001) to 6 h ( p < 0.001) of eCV exposure compared to room air control. We verified that even minimal eCV exposure (1 h) induces valosin-containing protein (VCP; p < 0.001), sequestosome-1/p62 (aberrant autophagy marker; p < 0.05), and aggresome formation (total polyUb-accumulation; p < 0.001) using immunoblotting (IB), fluorescence microscopy, and immunoprecipitation (IP). The inhibition of protein synthesis by 6 h of cycloheximide (50 lg/ml) treatment significantly ( p < 0.01) alleviates eCV-induced (1 h) aggresome bodies. We also observed that eCV (1 h)-induced protein aggregation can activate oxidative stress, apoptosis (caspase-3/7), and senescence ( p < 0.01) compared to room air controls. We verified using an autophagy inducer carbamazepine (20 lM, 6 h) or cysteamine (250 lM; 6 h, antioxidant) that eCV-induced changes in oxidative stress, poly-ub-accumulation, proteasomal activity, autophagy, apoptosis, and/or senescence could be controlled by autophagy induction. We further confirmed the role of acute eCV exposure on autophagy impairment in murine lungs (C57BL/6 and CD1) by IB (Ub, p62, VCP) and IP (VCP, p62), similar to in-vitro experiments. Innovation: In this study, we report for the first time that eCV exposure induces proteostasis/autophagy impairment leading to oxidative stress, apoptosis, and senescence that can be ameliorated by an autophagy inducer. Conclusion: eCV-induced autophagy impairment and aggresome formation suggest their potential role in chronic obstructive pulmonary disease-emphysema pathogenesis.

ObjectiveElectronic‐cigarettes (e‐cigarettes) are proposed to be a safer alternative to tobacco‐cigarettes. Hence, we evaluated if e‐cigarette‐vapors (eCV) impairs cellular proteostasis similar to cigarette‐smoke (CS)‐exposure.ResultsFirst, we evaluated the impact of eCV‐exposure (~2.5mg or 7.5mg) on Beas2b cells that showed significant increase in accumulation of ubiquitinated‐proteins (ub, insoluble‐fractions) with time‐dependent decrease in proteasomal‐activities from 1hr to 6hrs (p<0.01) of eCV‐exposure as compared to room‐air control. We verified that even minimal eCV‐exposure (1hr) induces valosin containing protein (VCP; p<0.01), sequestosome‐1/p62 (aberrant‐autophagy marker; p<0.05) and aggresome‐formation (ub‐accumulation) using immunoblotting (IB), fluorescence microscopy and immunopreciptation (IP). The inhibition of protein synthesis by 6hr cyclohexamide (50µg/ml) treatment significantly (p<0.01) alleviates eCV‐induced (1hr) aggresome‐bodies. We also observed that eCV (1hr) induced protein aggregation can activate apoptosis (caspase‐3/7) and senescence (SA‐β‐gal) activities (p<0.01) as compared to room‐air controls. We verified using carbamazepine (CBZ, 20µM, 6hrs) that eCV induced changes in ub‐accumulation, proteasomal activity, autophagy, apoptosis and senescence could all be controlled by autophagy induction by CBZ. We further confirmed the role of acute eCV‐exposure on autophagy impairment in murine lungs (C57BL/6 and CD1) by IB (ub, p62, VCP) and IP (VCP, p62) similar to in‐vitro experiments.ConclusioneCV induced autophagy impairment and aggresome‐formation activates apoptosis/senescence suggesting its potential role in COPD‐emphysema pathogenesis.