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

The mechanisms by which e-cigarette vaping (EV) affects lung health remain unclear. 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. RNA-seq of lung tissue from golden Syrian hamsters evaluated the persistence of lung stress responses (10 days after 5 days of EV exposure) and the effect of EV on host defense against influenza A virus and SARS-CoV-2. EV disrupted the barrier function of human distal lung cells through JNK stress response signaling, triggered autophagy with impaired flux, suppressed mTOR signaling and cell proliferation, and culminated in apoptosis. Transcriptional responses in EV-exposed hamster lungs revealed persistent activation of JNK signaling, autophagy, barrier dysfunction, tissue remodeling, and impaired Th1 immunity. EV increased SARS-CoV-2 viral burden, downregulated antiviral genes (Ifit1, Isg15, Nfkbia), and amplified oxidative stress and IL-12 signaling. Short-term EV exposure triggered stress-induced distal lung cell injury with persistent changes in antiviral immunity and molecular pathways associated with tissue remodeling. That may increase susceptibility to viral infections and contribute to lung disease.