Effects of Electronic (E)-cigarette Vapor and Cigarette Smoke in Cultured Vocal Fold Fibroblasts

The Toxicological Effects of e-Cigarette Use in the Upper Airway: A Scoping Review

OBJECTIVE

While evidence continues to emerge on the negative health effects of electronic cigarettes (e-cigarettes) on the lungs, little is known regarding their deleterious effects on the upper airway. The purpose of this review is to summarize the toxicological effects of e-cigarettes, and their components, on the upper airway.

DATA SOURCES

PubMed, SCOPUS, EMBASE databases.

REVIEW METHODS

Systematic searches were performed in accordance with Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines from 2003 to 2023. Studies were included if they investigated the toxicological effects of e-cigarette exposure on human or animal upper airway tissue. Two authors independently screened, reviewed, and appraised all included articles.

RESULTS

A total of 822 unique articles were identified, of which 53 met inclusion criteria and spanned subsites including the oral cavity (22/53 studies), nasal cavity/nasopharynx (13/53), multiple sites (10/53), larynx (5/53), trachea (2/53), and oropharynx (1/53). The most commonly observed consequences of e-cigarette use on the upper airway included: proinflammatory (15/53 studies), histological (13/53), cytotoxicity (11/53), genotoxicity (11/53), and procarcinogenic (6/53). E-cigarette humectants independently induced toxicity at multiple upper airway subsites, however, effects were generally amplified when flavoring(s) and/or nicotine were added. Across almost all studies, exposure to cigarette smoke exhibited increased toxicity in the upper airway compared with exposure to e-cigarette vapor.

CONCLUSION

Current data suggest that while e-cigarettes are generally less harmful than traditional cigarettes, they possess a distinct toxicological profile that is enhanced upon the addition of flavoring(s) and/or nicotine. Future investigations into underexamined subsites, such as the oropharynx and hypopharynx, are needed to comprehensively understand the effects of e-cigarettes on the upper airway.

Effects of Short-term Electronic(e)-Cigarette Aerosol Exposure in the Mouse Larynx

OBJECTIVES

The effects of electronic cigarettes (e-cigarettes) on the larynx are relatively unknown. This study examined the short-term effects of e-cigarette inhalation on cellular and inflammatory responses within the mouse laryngeal glottic and subglottic regions after exposure to pod-based devices (JUUL).

METHODS

Male C57BL6/J mice (8-9 weeks) were assigned to control (n = 9), JUUL flavors Mint (JMi; n = 10) or Mango (JMa; n = 10). JUUL mice were exposed to 2 h/day for 1, 5, and 10 days using the inExpose inhalation system. Control mice were in room air. Vocal fold (VF) epithelial thickness, cell proliferation, subglandular area and composition, inflammatory cell infiltration, and surface topography were evaluated in the harvested larynges. Mouse body weight and urinary nicotine biomarkers were also measured. Chemical analysis of JUUL aerosols was conducted using selective ion flow tube mass spectrometry.

RESULTS

JUUL-exposed mice had reduced body weight after day 5. Urinary nicotine biomarker levels indicated successful JUUL exposure and metabolism. Quantitative analysis of JUUL aerosol indicated that chemical constituents differ between JMi and JMa flavors. VF epithelial thickness, cellular proliferation, glandular area, and surface topography remained unchanged after JUUL exposures. Acidic mucus content increased after 1 day of JMi exposure. VF macrophage and T-cell levels slightly increased after 10 days of JMi exposures.

CONCLUSIONS

Short-term e-cigarette exposures cause minimal flavor- and region-specific cellular and inflammatory changes in the mouse larynx. This work provides a foundation for long-term studies to determine if these responses are altered with multiple e-cigarette components and concentrations.

LEVEL OF EVIDENCE

N/A Laryngoscope, 134:1316-1326, 2024.

Impact of Electronic Cigarettes on the Upper Aerodigestive Tract: A Comprehensive Review for Otolaryngology Providers

Objective

The use and effects of electronic (e)-cigarettes (e-cigs) are particularly relevant for otolaryngology providers as tobacco plays a major role in benign and malignant diseases of the upper aerodigestive tract. This review aims to (1) summarize the recent policies regarding e-cigs and important patterns of use and (2) serve as a comprehensive resource for clinical providers on the known biologic and clinical effects of e-cigs on the upper aerodigestive tract.

Data Sources

PubMed/MEDLINE.

Review Methods

We conducted a narrative review on (1) general information on e-cig use and informative findings in the lower respiratory system and a comprehensive review on (2) the effects of e-cigs on cell and animal models and the clinical implications of these products on human health as is relevant to otolaryngology.

Conclusions

Although e-cigs are likely less harmful than conventional cigarettes, preliminary research on e-cigs suggest several deleterious effects including in the upper aerodigestive tract. Due to this, there has been increased interest in restricting e-cig usage, particularly among the adolescent population, and caution in recommending e-cigs to current smokers.

Implications for Practice

Chronic e-cig use is likely to have clinical implications. It is critical for otolaryngology providers to be aware of the rapidly changing regulations and use patterns regarding e-cigs and how e-cigs influence human health, particularly with regards to the upper aerodigestive tract, to accurately council patients regarding potential risks and benefits of use.

Piezo1-expressing vocal fold epithelia modulate remodeling via effects on self-renewal and cytokeratin differentiation

Mechanoreceptors are implicated as functional afferents within mucosa of the airways and the recent discovery of mechanosensitive channels Piezo1 and Piezo2 has proved essential for cells of various mechanically sensitive tissues. However, the role for Piezo1/2 in vocal fold (VF) mucosal epithelia, a cell that withstands excessive biomechanical insult, remains unknown. The purpose of this study was to test the hypothesis that Piezo1 is required for VF mucosal repair pathways of epithelial cell injury. Utilizing a sonic hedgehog (shh) Cre line for epithelial-specific ablation of Piezo1/2 mechanoreceptors, we investigated 6wk adult VF mucosa following naphthalene exposure for repair strategies at 1, 3, 7 and 14 days post-injury (dpi). PIEZO1 localized to differentiated apical epithelia and was paramount for epithelial remodeling events. Injury to wildtype epithelium was most appreciated at 3 dpi. Shh^cre/+; Piezo1^loxP/loxP, Piezo2 ^loxP/+ mutant epithelium exhibited severe cell/nuclear defects compared to injured controls. Conditional ablation of Piezo1 and/or Piezo2 to uninjured VF epithelium did not result in abnormal phenotypes across P0, P15 and 6wk postnatal stages compared to heterozygote and control tissue. Results demonstrate a role for Piezo1-expressing VF epithelia in regulating self-renewal via effects on p63 transcription and YAP subcellular translocation-altering cytokeratin differentiation.