Impact of immunization against OxLDL on the pulmonary response to cigarette smoke exposure in mice

Exposure to nicotine-free and flavor-free e-cigarette vapors modifies the pulmonary response to tobacco cigarette smoke in female mice

Most of electronic cigarette (e-cigarette) users are also smoking tobacco cigarettes. Because of the relative novelty of this habit, very little is known on the impact of vaping on pulmonary health, even less on the potential interactions of dual e-cigarette and tobacco cigarette use. Therefore, we used well-established mouse models to investigate the impact of dual exposure to e-cigarette vapors and tobacco cigarette smoke on lung homeostasis. Groups of female BALB/c mice were exposed to room air, tobacco smoke only, nicotine-free flavor-free e-cigarette vapors only or both tobacco smoke and e-cigarette vapors. Moreover, since tobacco smoke and electronic cigarette vapors both affect circadian processes in the lungs, groups of mice were euthanized at two different time points during the day. We found that dual-exposed mice had altered lung circadian gene expression compared with mice exposed to tobacco smoke alone. Dual-exposed mice also had different frequencies of dendritic cells, macrophages, and neutrophils in the lung tissue compared with mice exposed to tobacco smoke alone, an observation also valid for B-lymphocytes and CD4+ and CD8+ T lymphocytes. Exposure to e-cigarette vapors also impacted the levels of immunoglobulins in the bronchoalveolar lavage and serum. Finally, e-cigarette and dual exposures increased airway resistance compared with mice exposed to room air or tobacco smoke alone, respectively. Taken together, these data suggest that e-cigarette vapors, even without nicotine or flavors, could affect how the lungs react to tobacco cigarette smoke exposure in dual users, potentially altering the pathological course triggered by smoking.

Critical importance of dietary methionine and choline in the maintenance of lung homeostasis during normal and cigarette smoke exposure conditions

Genetic predispositions and environmental exposures are regarded as the main predictors of respiratory disease development. Although the impact of dietary essential nutrient deficiencies on cardiovascular disease, obesity, and type II diabetes has been widely studied, it remains poorly explored in chronic respiratory diseases. Dietary choline and methionine deficiencies are common in the population, and their impact on pulmonary homeostasis is currently unknown. Mice were fed choline- and/or methionine-deficient diets while being exposed to room-air or cigarette smoke for up to 4 wk. Lung functions were assessed using the FlexiVent. Pulmonary transcriptional activity was assessed using gene expression microarrays and quantitative PCR. Immune cells, cytokines, and phosphatidylcholine were quantified in the bronchoalveolar lavage. In this study, we found that short-term dietary choline and/or methionine deficiencies significantly affect lung function in mice in a reversible manner. It also reduced transcriptional levels of collagens and elastin as well as pulmonary surfactant phosphatidylcholine levels. We also found that dietary choline and/or methionine deficiencies markedly interfered with the pulmonary response to cigarette smoke exposure, modulating lung function and dampening inflammation. These findings clearly show that dietary choline and/or methionine deficiencies can have dramatic pathophysiological effects on the lungs and can also affect the pathobiology of cigarette smoke-induced pulmonary alterations. Expanding our knowledge in the field of "nutri-respiratory research" may reveal a crucial role for essential nutrients in pulmonary health and disease, which may prove to be as relevant as genetic predispositions and environmental exposures.