Ion transport mechanisms for smoke inhalation–injured airway epithelial barrier


Smoke inhalation injury is the leading cause of death in firefighters and victims. Inhaled hot air and toxic smoke are the predominant hazards to the respiratory epithelium. We aimed to analyze the effects of thermal stress and smoke aldehyde on the permeability of the airway epithelial barrier. Transepithelial resistance (RTE) and short-circuit current (ISC) of mouse tracheal epithelial monolayers were digitized by an Ussing chamber setup. Zonula occludens-1 tight junctions were visualized under confocal microscopy. A cell viability test and fluorescein isothiocyanate-dextran assay were performed. Thermal stress (40 °C) decreased RTE in a two-phase manner. Meanwhile, thermal stress increased ISC followed by its decline. Na+ depletion, amiloride (an inhibitor for epithelial Na+ channels [ENaCs]), ouabain (a blocker for Na+/K+-ATPase), and CFTRinh-172 (a blocker of cystic fibrosis transmembrane regulator [CFTR]) altered the responses of RTE and ISC to thermal stress. Steady-state 40 °C increased activity of ENaCs, Na+/K+-ATPase, and CFTR. Acrolein, one of the main oxidative unsaturated aldehydes in fire smoke, eliminated RTE and ISC. Na+ depletion, amiloride, ouabain, and CFTRinh-172 suppressed acrolein-sensitive ISC, but showed activating effects on acrolein-sensitive RTE. Thermal stress or acrolein disrupted zonula occludens-1 tight junctions, increased fluorescein isothiocyanate-dextran permeability but did not cause cell death or detachment. The synergistic effects of thermal stress and acrolein exacerbated the damage to monolayers. In conclusion, the paracellular pathway mediated by the tight junctions and the transcellular pathway mediated by active and passive ion transport pathways contribute to impairment of the airway epithelial barrier caused by thermal stress and acrolein.

Thermal stress and acrolein are two essential determinants for smoke inhalation injury, impairing airway epithelial barrier.

Transcellular ion transport pathways via the ENaC, CFTR, and Na/K-ATPase are interrupted by both thermal stress and acrolein, one of the most potent smoke toxins.

Heat and acrolein damage the integrity of the airway epithelium through suppressing and relocating the tight junctions.

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Epithelial Na+ channels


Cystic fibrosis transmembrane regulator

R TE :

Transepithelial resistance

I SC :

Short-circuit current


Mouse tracheal epithelial


Fluorescein isothiocyanate


Human bronchial epithelial


Dimethyl sulfoxide


Zonula occludens-1


Phase 1


Phase 2


Amiloride-sensitive ISC


K+ channels


Reactive oxygen species


Ca2+-activated Cl channels




Mitogen-activated protein kinase


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This work was supported by the grants from the National Institute of Health (NIH HL134828) and the National Natural Science Foundation of China (NSFC 81670010).

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Hong-Long Ji conceived study, designed experiments, edited manuscript, and approved submission. Jianjun Chang, Zaixing Chen, and Hong-Guang Nie performed experiments, analyzed data, and plotted graphs. Jianjun Chang, Runzhen Zhao, Hong-Guang Nie, and Zaixing Chen prepared manuscript.

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Correspondence to Hong-Guang Nie or Hong-Long Ji.

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Chang, J., Chen, Z., Zhao, R. et al. Ion transport mechanisms for smoke inhalation–injured airway epithelial barrier. Cell Biol Toxicol (2020).

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  • Thermal stress
  • Acrolein
  • Tracheal epithelial monolayers
  • Ion transport
  • Tight junctions