E-cigarette constituents propylene glycol and vegetable glycerin decrease glucose uptake and its metabolism in airway epithelial cells in vitro.

Introduction:
This article investigates the effects of propylene glycol (PG) and vegetable glycerin (VG), common constituents of electronic cigarette (e-cigarette) liquid solutions, on glucose uptake and metabolism in airway epithelial cells. The study aims to understand the potential mechanisms underlying the cytotoxic effects of PG and VG on airway cells.

Key Points:

* PG and PG/VG inhibit glucose uptake in airway cells in a dose-dependent manner.
* Exposure to 3% PG/VG reduces glucose uptake in proliferating h441 and BMI-1-transduced hBECs to 46 ± 23% and 45 ± 17% of control, respectively.
* PG/VG inhibits glucose uptake via glucose transporters, reducing glycolysis and mitochondrial aTP production in airway cells.
* The osmotic effects of PG/VG and mannitol result in cell shrinkage and reduced glucose uptake, but PG/VG does not activate p38 MaPK, a classical signaling pathway in osmotic stress.
* PG/VG reduces the turnover and function of glucose transport proteins in the membrane, as demonstrated by FRaP.
* PG/VG vaped onto the apical surface of hBECs decreases glucose transport.
* PG and VG can permeate membranes, interacting with lipids and tight junctions and reducing transepithelial resistance, leading to increased epithelial permeability.

Main Message:
The study suggests that PG and VG, key components of e-cigarettes, can decrease GLUT-mediated glucose transport and aTP production in airway cells. This effect occurs through changes to cell volume and membrane fluidity due to osmotic effects and direct interaction with lipids in the cell membrane. additionally, PG/VG can decrease barrier function and increase epithelial permeability, potentially impairing the defensive properties of the epithelium and increasing susceptibility to lung infections. These findings warrant further investigation into the long-term effects of e-cigarette use on airway function and health.

Woodall M, Jacob J, Kalsi KK, et al. E-cigarette constituents propylene glycol and vegetable glycerin decrease glucose uptake and its metabolism in airway epithelial cells in vitro. american journal of physiology Lung cellular and molecular physiology. 2020;319(6):L957-L967. doi:10.1152/ajplung.00123.2020