Assessing the Respiratory Toxicology of E-cigarette Aerosols under Real-Use Patterns and Exposure Doses Using an Artificial Lung System

HAOXUAN CHEN, Airi Harui, Yu Feng, Michael D. Roth, Yifang Zhu, University of California, Los Angeles

     Abstract Number: 289
     Working Group: Health-Related Aerosols

Abstract
Despite several in vitro and in vivo studies suggesting the potential toxicity of e-cigarette (e-cig) aerosols, the actual health risks of using e-cigs remain poorly understood, partially due to the current toxicology testing method cannot accurately represent the inhalation exposure that happens in human lungs. To better understand the respiratory toxicology of e-cig aerosols under real-use patterns and exposure doses, we developed an artificial lung system that consists of a 6-L lung chamber with a 3D-printed human airway structure. The artificial lung can continuously breathe (i.e., inhale and exhale) with the temperature and humidity independently controlled to approximate human lungs. Additionally, the system integrates programmable e-cig puffing cooperating with the artificial lung’s inhalation, enabling the simulation of various e-cig using patterns, including varying puff volumes and vaping frequencies.

By integrating the air-liquid-interface (ALI) culture of primary human bronchial epithelial (HBE) cells into the lung chamber, we have successfully conducted an e-cig exposure experiment for a total of 108 puffs for seven hours per day over two consecutive days. Our results show that the mitochondrial membrane potential of HBE cells in the air control and e-cig exposure groups are comparable. In contrast, the e-cig exposure group shows moderately elevated inflammatory responses, as suggested by several pro-inflammatory biomarkers. Ongoing studies will characterize the exposure doses of e-cig aerosols when the artificial lung is either ventilated or unventilated. In addition, we will comprehensively characterize and compare the respiratory toxicity of e-cig aerosols from e-liquid of different formulations by evaluating cytokine/chemokine productions and RNA expressions.

This study offers novel insights into the respiratory toxicology of e-cig aerosols under real-use patterns and exposure doses, as well as an innovative in vitro exposure system that can replicate typical exposure scenarios for various aerosols.