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Flavored e-cigarette liquids and cinnamaldehyde impair respiratory innate immune cell function
Phillip W Clapp1,2, Erica A Pawlak2, Justin T Lackey3
1Curriculum in Toxicology, School of Medicine, University of North Carolina, Chapel Hill, North Carolina.
Summary
Flavored e-liquids, particularly those with cinnamaldehyde, can suppress key respiratory immune cell functions like phagocytosis. This highlights the need for toxicological evaluation of e-liquid flavorings to ensure consumer safety.
Area of Science:
- Immunology
- Toxicology
- Respiratory Medicine
Background:
- Innate immune cells in the respiratory tract defend against pathogens.
- Compromised immune function increases infection susceptibility and inflammation.
- Effects of flavored e-liquids on respiratory immune cells are largely unknown.
Purpose of the Study:
- To investigate the impact of flavored e-liquids on human alveolar macrophages, neutrophils, and NK cells.
- To identify specific flavoring agents responsible for immune suppression.
Main Methods:
- Primary human immune cells were exposed to various concentrations of seven flavored, nicotine-free e-liquids.
- Functional assays measured phagocytosis, NET formation, cytokine production, and NK cell cytotoxicity.
- Mass spectrometry identified e-liquid components, with cinnamaldehyde further tested independently.
Main Results:
- Three e-liquids containing cinnamaldehyde demonstrated dose-dependent immunosuppressive effects.
- Cinnamaldehyde alone replicated the immune cell dysfunction observed with e-liquid exposure.
- Macrophage phagocytosis impairment by cinnamaldehyde was reversible with a reducing agent.
Conclusions:
- Cinnamaldehyde is a potential immunosuppressive agent in e-liquids.
- Further toxicological assessment of e-liquid flavorings is crucial for regulatory guidance.
