Propylene Glycol and Vegetable Glycerin E-cigarette Aerosols Disrupt Mucociliary Function and Cause Cytotoxicity in Human Airway Epithelium

Electronic cigarettes or e-cigarettes were introduced as a “healthier alternative” to conventional cigarettes and as a tool to facilitate smoking cessation though their safety and effectiveness as a smoking cessation tool are still debated. Nicotine, a common psychoactive substance found in e-cigarettes, has been shown to cause irritation and inflammation in the airways. However, the effects of e-cigarette aerosols, particularly the base components such as propylene glycol (PG) and vegetable glycerin (VG), on the airways, are less well understood. We hypothesized that PG and VG aerosol exposure would negatively impact mucociliary clearance and induce an inflammatory response in airway epithelial cells. To test this hypothesis, cultured human airway epithelial cells isolated from the inferior turbinate of healthy donors were exposed to an e-cigarette aerosol containing PG and VG. Exposure led to an increase in ciliary beat frequency (CBF), a key factor in mucociliary clearance. An LDH cytotoxicity assay revealed an increase in cell damage following exposure. Taken together, this work suggests that e-cigarette aerosol generated from carrier substances is not innocuous.