Acute Acrolein Exposure Induces Impairment of Vocal Fold Epithelial Barrier Function.

Xinxin Liu,M Preeti Sivasankar,Wei Zheng,Li-Mei Chen

doi:10.1371/journal.pone.0163237

Abstract

Acrolein is a ubiquitous pollutant abundant in cigarette smoke, mobile exhaust, and industrial waste. There is limited literature on the effects of acrolein on vocal fold tissue, although there are clinical reports of voice changes after pollutant exposures. Vocal folds are responsible for voice production. The overall objective of this study was to investigate the effects of acrolein exposure on viable, excised vocal fold epithelial tissue and to characterize the mechanism underlying acrolein toxicity. Vocal fold epithelia were studied because they form the outermost layer of the vocal folds and are a primary recipient of inhaled pollutants. Porcine vocal fold epithelia were exposed to 0, 50, 100, 500, 900 or 1300 μM of acrolein for 3 hours; the metabolic activity, epithelial resistance, epithelial permeability, tight junction protein (occludin and claudin 3) expression, cell membrane integrity and lipid peroxidation were investigated. The data demonstrated that acrolein exposure at 500 μM significantly reduced vocal fold epithelial metabolic activity by 27.2% (p≤0.001). Incubation with 100 μM acrolein caused a marked increase in epithelial permeability by 130.5% (p<0.05) and a reduction in transepithelial electrical resistance (TEER) by 180.0% (p<0.001). While the expression of tight junctional protein did not change in acrolein-treated samples, the cell membrane integrity was significantly damaged with a 45.6% increase of lipid peroxidation as compared to controls (p<0.05). Taken together, these data provide evidence that acute acrolein exposure impairs vocal fold epithelial barrier integrity. Lipid peroxidation-induced cell membrane damage may play an important role in reducing the barrier function of the epithelium.

Highlights

The vocal folds are paired, multi-layered, membranous tissues within the larynx
This study is exempt from the Institutional Animal Care and Use Committee (IACUC) of Purdue University, because the tissues were obtained from the slaughterhouse after sacrifice of pigs
In control tissues without acrolein, the transepithelial electrical resistance (TEER) values increased by 55.8 OÁcm2 after 3 hr incubation, while the acrolein-treated tissues showed a 44.7 OÁcm2 decrease in the TEER value, a reduction of 180.0% compared to the controls (N = 7, t = 5.023, p < 0.001) (Fig 2A), suggesting a reduced tightness of this vocal fold epithelial monolayer

Summary

Introduction

The vocal folds are paired, multi-layered, membranous tissues within the larynx. The outermost surface of vocal folds consists of 5 to 10 cell layers of squamous. Vocal Fold Epithelium Exposure to Acrolein epithelial cells with tight junctions [2]. The epithelium forms a physical barrier to prevent inhaled xenobiotic penetration and protect underlying connective tissue and muscle. This stratified structure is unique compared to epithelia in other parts of respiratory system. The vocal fold epithelium secretes mucins, transports ions, and is associated with water fluxes to actively control surface composition [3,4,5]

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