Department of Cellular and Molecular Biology, University of Texas Health Science Center at Tyler, 11937 US Hwy 271, Tyler, TX, 75708, USA.
Institute of Health Sciences, China Medical University, Shenyang, 110122, Liaoning, China.
Cell Biol Toxicol. 2020 Dec;36(6):571-589. doi: 10.1007/s10565-020-09545-1. Epub 2020 Jun 25.
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 (R) and short-circuit current (I) 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 R in a two-phase manner. Meanwhile, thermal stress increased I 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 R and I 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 R and I. Na depletion, amiloride, ouabain, and CFTRinh-172 suppressed acrolein-sensitive I, but showed activating effects on acrolein-sensitive R. 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. Graphical abstract 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.
烟雾吸入性损伤是消防员和受害者死亡的主要原因。吸入的热空气和有毒烟雾是呼吸道上皮的主要危害。我们旨在分析热应激和烟雾醛对气道上皮屏障通透性的影响。通过 Ussing 室装置对小鼠气管上皮单层的跨上皮电阻（R）和短路电流（I）进行数字化。利用共聚焦显微镜观察封闭蛋白-1 紧密连接。进行细胞活力测试和荧光素异硫氰酸酯-葡聚糖测定。热应激（40°C）以两相方式降低 R。同时，热应激增加了 I，随后 I 下降。钠耗竭、阿米洛利（上皮钠通道 [ENaC] 的抑制剂）、哇巴因（Na/K-ATP 酶的阻断剂）和 CFTRinh-172（囊性纤维化跨膜转导调节因子 [CFTR] 的阻断剂）改变了 R 和 I 对热应激的反应。稳态 40°C 增加了 ENaC、Na/K-ATP 酶和 CFTR 的活性。丙烯醛，火灾烟雾中主要的氧化不饱和醛之一，消除了 R 和 I。钠耗竭、阿米洛利、哇巴因和 CFTRinh-172 抑制了对丙烯醛敏感的 I，但对丙烯醛敏感的 R 有激活作用。热应激或丙烯醛破坏了封闭蛋白-1 紧密连接，增加了荧光素异硫氰酸酯-葡聚糖的通透性，但不会导致细胞死亡或脱落。热应激和丙烯醛的协同作用加剧了单层的损伤。总之，紧密连接介导的细胞旁途径和主动和被动离子转运途径介导的细胞内途径导致热应激和丙烯醛引起的气道上皮屏障损伤。
