Electronic-Cigarette Vehicles and Flavoring affect Lung Function and Immune Responses in a Murine Model.

Introduction:
This article presents a study on the effects of electronic nicotine delivery systems (ENDS) on lung function and immune responses in a mouse model. The study focuses on the nearly ubiquitous e-cig delivery vehicles, vegetable glycerin (VG) and propylene glycol (PG), used with a specific 70% /30% ratio, with or without vanilla flavoring.

Key Points:

* The study used adult female C57BL/6 mice and exposed them to filtered air, 70% /30% VG /PG, or 70% /30% VG/PG with a French vanilla flavoring for 2 hours a day for 6 weeks.
* Prior to sacrifice, lung function was assessed using whole-body plethysmography and flexiVent lung function testing with methacholine challenge.
* Exposures to VG /PG plus vanilla e-cig aerosol increased lung tidal and minute volumes and tissue damping.
* Immunophenotyping of lung immune cells revealed an increased number of dendritic cells, CD4 +T cells, and CD19 +B cells in the VG /PG-exposed group compared to air, irrespective of the presence of vanilla flavoring.
* quantification of bioactive lung lipids demonstrated a >3-fold increase of 2-arachidonoylglycerol (2-aG), an anti-inflammatory mediator, and a 2-fold increase of 12-hydroxyeicosatetraenoic acid (12-hETE), another inflammatory mediator, following VG /PG exposure, with or without vanilla flavoring.
* The two e-cig aerosols dysregulated the expression of lung genes, with the VG /PG e-cig aerosol dysregulating genes related to biotransformation, transcription factors expressed in pulmonary surfactant, synuclein-alpha, and Il-6.
* The VG /PG plus vanilla aerosol up-regulated the expression of hpx, a biomarker of oxidative damage.
* There was no overlap in the genes that were dysregulated by the two e-cig aerosols, suggesting that flavor may contribute to the induction of molecular changes via distinct mechanisms.

Main Message:
The study suggests that e-cig aerosols, even without nicotine or other additives, can have harmful effects on lung function and immune responses in mice. The study found that exposure to VG /PG aerosol, with or without vanilla flavoring, disrupted immune homeostasis and altered lung gene expression. These findings highlight the need for further research on the long-term health effects of e-cig use, particularly regarding the use of e-cig delivery vehicles.

Szafran BN, Pinkston R, Perveen Z, et al. Electronic-Cigarette Vehicles and Flavoring affect Lung Function and Immune Responses in a Murine Model. International journal of molecular sciences. 2020;21(17). doi:10.3390/ijms21176022