Single-Cell RNA Sequencing Reveals Heterogeneity of ALI Model and Epithelial Cell Alterations after Exposure to Electronic Cigarette Vapor

Abstract

Abstract Background Electronic cigarettes (e-cigarettes) have been advertised as a healthier alternative to traditional cigarettes; however, their exact effects on the bronchial epithelium are poorly understood. Air-liquid interface (ALI) culture allows human primary bronchial epithelial cells to differentiate into bronchial epithelium (ALI-HBE), providing an in vitro model that simulates the biological characteristics of normal bronchial epithelium. Methods Single-cell RNA sequencing of ALI-HBE was used to reveal previously unrecognized transcriptional heterogeneity within the human bronchial epithelium and cell type–specific responses to acute exposure to e-cigarette vapor (e-vapor) containing distinct components (nicotine and/or flavoring). Results Acute exposure to e-vapor containing nicotine affected gene expression related to secretory function and basal-to-secretory transformation. In addition, acute exposure to e-vapor containing flavoring might promote susceptibility to virus infection and activate epithelial-to-mesenchymal transition. Conclusion The ALI-HBE model recapitulates the heterogeneity and transcriptional characteristics of human bronchial epithelium. Single-cell sequencing data provided high-resolution insights into e-vapor–induced remodeling of bronchial epithelium. The data also indicate factors on bronchial epithelial cells that may promote SARS-CoV-2 infection and suggest therapeutic targets for restoring normal bronchial epithelium function after e-cigarette use.