Mainstream Cigarette Smoke Impacts the Mouse Vocal Fold Epithelium and Mucus Barrier.

OBJECTIVES/HYPOTHESIS: Cigarette smoke (CS) is a primary risk factor for the development of numerous benign and malignant laryngeal diseases. The epithelium and mucus lining the vocal folds (VF) are the first barriers against CS. The primary objective of this study was to investigate epithelial and mucus barrier changes in the mouse laryngeal mucosa upon exposure to subacute CS. The secondary objective was to compare mucus barrier changes in mice and human smokers and nonsmokers. Study Design Animal model.

METHODS

Mice were exposed to CS for 4 weeks for 4 hours (N = 12, high dose [HD]) or 1 hour (N = 12, low dose [LD]) per day. Air-exposed mice were used as a control group (N = 10). Larynges were harvested and VF epithelial barrier integrity was evaluated including cellular proliferation and expression of cell junctions. We also investigated mucus production by examining mucus cell area and mucin expression in mice and human smokers and nonsmokers.

RESULTS

HD CS increased VF epithelial cellular proliferation but did not alter the expression of cell junctions. HD CS also induced hypertrophy of the mucus-producing submucosal glands. However, only LD CS increased MUC5AC gene expression. MUC5AC staining appeared elevated in laryngeal specimens from smokers, but this was not significant as compared to nonsmokers.

CONCLUSIONS

These findings help us identify potential adaptive mechanisms to CS exposure as well as set the foundation for further study of key aspects of epithelial and mucus barrier integrity that may be implicated in laryngeal disease development following prolonged smoking.

LEVEL OF EVIDENCE

NA Laryngoscope, 131:2530-2539, 2021.