E-cigarette exposure triggers distal lung cell injury, persistent lung stress response, and anti-viral immune...

The mechanisms by which e-cigarette vaping (EV) affects lung health remain unclear. Clinical data from clusters of EV-associated lung injury indicate that EV damages distal lung parenchyma and increases vulnerability to second-hit injury, including respiratory viral infections. Using human lung endothelial and epithelial cells and precision-cut lung slices, we investigated the mechanisms underlying distal lung cell injury and repair triggered by brief (24-hour) EV exposure. Using RNA sequencing of lung tissue from Golden Syrian hamsters, we evaluated the persistence of lung stress responses (10 days after 5 days of EV exposure and determined the impact of EV on host defense against influenza A virus (IAV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections. EV disrupted the barrier function of human distal lung cells through JNK stress-response signaling, triggered autophagy with impaired autophagolysosomal degradation, suppressed mTOR signaling and cell proliferation, and culminated in apoptosis. Analysis of transcriptional responses in EV-exposed hamster lungs revealed persistent activation of pathways involving JNK signaling, autophagy, barrier dysfunction, tissue remodeling, and impaired Th1 immunity. EV pre-exposure increased the viral burden of SARS-CoV-2, downregulated antiviral genes (Ifit1, Isg15, Nfkbia), and altered Stat1 and Irf7 immune signaling, while amplifying oxidative stress and IL-12 signaling. These findings show that short-term EV exposure triggered stress-induced distal lung cell injury with persistent changes in antiviral immunity and molecular pathways associated with tissue remodeling. When sustained, as with habitual EV use, these alterations may increase susceptibility to respiratory viral infections and contribute to the development of chronic lung disease.