Repetitive Exposure to Nicotine-Free Vaping Impairs Airway Defences and Delays Recovery

E-cigarette use, or vaping, is increasing in prevalence, especially among adolescents. There is a paucity of information on the impact of e-cigarette aerosols on lung health, particularly to the airway protective components. In this study, disruptions to airway protective functions in response to increasing repetitive exposure to nicotine-free e-cigarette aerosols were examined. The recovery capability of the airway defence was also investigated.

Cultured primary nasal airway cells from five healthy individuals were exposed to repetitive exposures to e-cigarette aerosols. Cilia function was analysed via high-speed video microscopy, while epithelial barrier integrity was assessed through trans-epithelial electrical resistance measurements and immunofluorescence. Cytokine secretion was assessed using multiplex screening.

Significant impairment in cilia function and epithelial barrier integrity was observed after 24 or more vaping exposures. Cilia beating frequency declined by 18.6% (6.78 ± 0.23 Hz) after 24 sessions and by 53.0% (3.91 ± 0.27 Hz) after 60 sessions (p < 0.01). Trans-epithelial electrical resistance values dropped by 45.6% (315.37 ± 13.38 Ωcm²) after 24 sessions and by 77.4% (131.29 ± 6.84 Ωcm²) after 60 sessions (p < 0.01). Nicotine-free aerosols disrupted Occludin-1 and ZO-1 expression but not E-cadherin. Cytokine analysis showed increased secretion of IL-1ra, IL-6, FGF-basic, IFN-γ, and VEGF following 36 vaping sessions. Recovery experiments indicated cilia function normalised within 48 h, while epithelial barrier required up to 72 h.

Repetitive vaping progressively impairs airway protective functions in vitro. While cilia function and epithelial integrity recover in the short term, the delay may increase susceptibility to infections.