Linking E-Cigarette Aerosol Characteristics to Mechanisms of Pulmonary Toxicity

摘要关于其生理化学特征或与健康相关的影响， 电子烟（e-cig）使用者吸入的大量气溶胶。因此，我们召集了一个 多学科团队，结合了气溶胶科学，体外高通量筛选（HTS）， 活体动物成像和吸入毒理学，以解决这些问题。我们的首要目标是- 了解雾化器参数和电子烟液中的关键成分如何在不同的电子烟中共享 品牌，有助于不希望的气溶胶特性和肺毒性。基于我们的体外和体内 体内初步数据，工作假设是（1）加热线圈温度，化学成分和 电子烟液中主要成分的蒸气压可以以预测的方式与电子烟气溶胶特性相关联， （2）采用空气-液体界面的模拟肺暴露模型将提供 对气溶胶成分的稀释和分散及其对上皮细胞毒性的潜力的新见解; 和（3）HTS、气溶胶成分和终点毒性测量之间的相关性将在以下情况下得到验证： 动物在体内暴露于电子烟气溶胶。提出了三个具体目标：（1）系统地改变电子商务， cig设备参数和电子液体成分，以确定其对气溶胶理化特性的影响， （2）将气道上皮细胞暴露于电子烟气溶胶中，就像在人体中发生的那样 肺在vaping和确定由特定的生理化学特征产生的毒性签名。以及（3） 使用电子烟气溶胶测定暴露于电子烟气溶胶引起的急性和亚慢性肺毒性 转基因动物该提案有几个新颖的方面，包括：（1）关注关键的电子烟， 标志特征（线圈组成、线圈电阻和施加电压）和电子液体组分（丙二醇 (PG)、植物甘油（VG）、尼古丁和调味料），这些成分在多种品牌中共享，并且 制定预测性评估的目标，将其对气溶胶特性的影响与特定毒性联系起来;（2） 使用基于机制的HTS系统地筛选大量电子烟气溶胶，并识别 具有需要进一步研究的毒性信号;（3）开发通气人工肺模型EM- 采用原代人支气管上皮细胞（HBEC）/气液界面（ALI）培养， 评估人体暴露并检测上皮细胞毒性的早期信号;以及（4）重点验证研究 使用转基因小鼠和活体动物成像评估急性和重复暴露对 体内肺。这项研究的意义在于，它将确定关键的电子烟设计参数和电子液体 成分，可以很容易地通过HTS评估，但以预测的方式联系到更详细的 使用人类人工肺和动物体内暴露测量毒性。此外，预计， 这些相关的成果和电子烟的特点，这是共同的大多数品牌，将促进发展， 法规指南和电子烟设计标准的修订。

ABSTRACT Little is known regarding the physiochemical characteristics or health-related effects for the large array of aerosols that are inhaled by electronic cigarette (e-cig) users. We have therefore assembled a multidisciplinary team that combines expertise in aerosol sciences, in vitro high throughput screening (HTS), live animal imaging, and inhalation toxicology in order to address these issues. Our primary objective is to un- derstand how atomizer parameters and key ingredients in e-liquid, which are shared across different e-cig brands, contribute to undesirable aerosol characteristics and pulmonary toxicity. Based on our in vitro and in vivo preliminary data, the working hypotheses are (1) the heating coil temperature, chemical composition and vapor pressure of the major ingredients in e-liquid can be linked in a predictive manner to e-cig aerosol charac- teristics associated with toxicity; (2) a simulated lung exposure model employing air-liquid interface will provide novel insight into the dilution and dispersion of aerosol components and their potential for epithelial toxicity; and (3) correlations between HTS, aerosol composition, and endpoint toxicity measures will be validated when animals are exposed to e-cig aerosols in vivo. Three specific aims are proposed: (1) To systematically vary e- cig device parameters and e-liquid compositions to determine their impacts on aerosol physiochemical charac- teristics and in vitro toxicity; (2) To expose airway epithelial cells to e-cig aerosols as would occur in the human lung during vaping and determine toxicity signatures resulting from specific physiochemical features.; and (3) To determine acute and sub-chronic lung toxicity profiles resulting from exposures to e-cig aerosols us-ing transgenic animals. There are several novel aspects of this proposal that include: (1) a focus on key e-cig de- sign features (coil composition, coil resistance, and applied voltage) and e-liquid components (propylene glycol (PG), vegetable glycerin (VG), nicotine, and flavoring), that are shared across a wide range of brands, with a goal of developing predictive assessments linking their impact on aerosol characteristics to specific toxicity; (2) use of a mechanism-based HTS to systematically screen a large number of e-cig aerosols and identify those with toxicity signals that warrant further investigation; (3) development of a ventilated artificial lung model em- ploying primary human bronchial epithelial cells (HBEC)/air-liquid interface (ALI) cultures to carry out a detailed assessment of human exposure and detect early signals of epithelial toxicity; and (4) focused validation studies using transgenic mice and live animal imaging to assess the toxicity of acute and repeated exposure on the lung in vivo. This proposed research is significant in that it will identify key e-cig design parameters and e-liquid ingredients that can be readily assessed by HTS yet are linked in a predictive manner to more detailed measures of toxicity using human artificial lung and in vivo animal exposures. In addition, it is expected that these correlative outcomes and e-cig features, which are common to most brands, will facilitate the develop- ment of regulatory guidelines and e-cig design standards.