Background. Most of electronic cigarette (e-cigarette) users are also smoking tobacco cigarettes. Due to 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. Methods. 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. Results. We found that dual-exposed mice had altered lung circadian gene expression compared to mice exposed to tobacco smoke alone. Dual-exposed mice also had different frequencies of dendritic cells, macrophages and neutrophils in the lung tissue compared 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 to mice exposed to room air or tobacco smoke alone, respectively. Discussion. 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.

中文翻译：

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暴露于无尼古丁和无味的电子烟蒸气会改变雌性小鼠对烟草香烟烟雾的肺部反应。

背景。大多数电子烟（电子烟）用户也在抽烟。由于这种习惯的相对新颖性，对于雾化对肺部健康的影响知之甚少，甚至对双重电子烟和吸烟的潜在相互作用也知之甚少。方法。因此，我们使用完善的小鼠模型来研究双重暴露于电子烟蒸气和烟草香烟烟雾对肺稳态的影响。将各组BALB / c雌性小鼠暴露在室内空气中，仅暴露于烟草烟雾，仅暴露于无尼古丁的无味电子烟蒸气，或暴露于烟草烟雾和电子烟蒸气。此外，由于烟草烟雾和电子香烟蒸气都影响肺部的昼夜节律，因此在一天中的两个不同时间点对小鼠进行安乐死。结果。我们发现，与仅暴露于烟草烟雾的小鼠相比，双重暴露的小鼠肺昼夜节律基因表达发生了改变。与仅暴露于烟草烟雾的小鼠相比，双暴露小鼠的肺组织中树突状细胞，巨噬细胞和嗜中性粒细胞的频率也不同，这一观察结果对B淋巴细胞和CD4也有效⁺和CD8 ⁺ T淋巴细胞。暴露于电子烟蒸气中也会影响支气管肺泡灌洗液和血清中免疫球蛋白的水平。最后，与单独暴露于室内空气或单独吸烟的小鼠相比，电子烟和双重暴露分别增加了呼吸道阻力。讨论。综上所述，这些数据表明，即使没有尼古丁或香精，电子烟蒸气也可能影响肺部双重使用者对烟草烟雾接触的反应，从而可能改变吸烟引发的病理过程。