Walther Straub Institute of Pharmacology and Toxicology, Member of the German Center for Lung Research (DZL), LMU Munich, Nußbaumstr. 26, 80336, Munich, Germany.
Bundeswehr Institute of Pharmacology and Toxicology, Munich, Germany.
Pflugers Arch. 2018 Aug;470(8):1231-1241. doi: 10.1007/s00424-018-2148-6. Epub 2018 May 12.
Transient receptor potential A1 (TRPA1) channels were originally characterized in neuronal tissues but also identified in lung epithelium by staining with fluorescently coupled TRPA1 antibodies. Its exact function in non-neuronal tissues, however, is elusive. TRPA1 is activated in vitro by hypoxia and hyperoxia and is therefore a promising TRP candidate for sensing hyperoxia in pulmonary epithelial cells and for inducing alveolar epithelial hyperplasia. Here, we isolated tracheal, bronchial, and alveolar epithelial cells and show low but detectable TRPA1 mRNA levels in all these cells as well as TRPA1 protein by Western blotting in alveolar type II (AT II) cells. We quantified changes in intracellular Ca ([Ca]) levels induced by application of hyperoxic solutions in primary tracheal epithelial, bronchial epithelial, and AT II cells isolated from wild-type (WT) and TRPA1-deficient (TRPA1-/-) mouse lungs. In all cell types, we detected hyperoxia-induced rises in [Ca] levels, which were not significantly different in TRPA1-deficient cells compared to WT cells. We also tested TRPA1 function in a mouse model for hyperoxia-induced alveolar epithelial hyperplasia. A characteristic significant increase in thickening of alveolar tissues was detected in mouse lungs after exposure to hyperoxia, but not in normoxic WT and TRPA1-/- controls. Quantification of changes in lung morphology in hyperoxic WT and TRPA1-/- mice, however, again revealed no significant changes. Therefore, TRPA1 expression does neither appear to be a key player for hyperoxia-induced changes in [Ca] levels in primary lung epithelial cells, nor being essential for the development of hyperoxia-induced alveolar epithelial hyperplasia.
瞬时受体电位 A1（TRPA1）通道最初在神经元组织中被描述，但也通过荧光偶联的 TRPA1 抗体染色在肺上皮细胞中被鉴定。然而，其在非神经元组织中的确切功能尚不清楚。TRPA1 在体外被低氧和高氧激活，因此是一种有前途的 TRP 候选物，可用于感知肺上皮细胞中的高氧，并诱导肺泡上皮细胞增生。在这里，我们分离了气管、支气管和肺泡上皮细胞，并通过 Western blot 在肺泡 II 型（AT II）细胞中显示所有这些细胞以及 TRPA1 蛋白都有低但可检测到的 TRPA1 mRNA 水平。我们定量了在 WT 和 TRPA1 缺陷（TRPA1-/-）小鼠肺中分离的原代气管上皮细胞、支气管上皮细胞和 AT II 细胞中应用高氧溶液引起的细胞内 Ca（[Ca]）水平的变化。在所有细胞类型中，我们都检测到高氧诱导的 [Ca]水平升高，在 TRPA1 缺陷细胞中与 WT 细胞相比没有显著差异。我们还在高氧诱导的肺泡上皮细胞增生的小鼠模型中测试了 TRPA1 的功能。在高氧暴露后，在小鼠肺部检测到肺泡组织增厚的特征性显著增加，但在正常氧合的 WT 和 TRPA1-/-对照中没有。然而，对高氧 WT 和 TRPA1-/-小鼠肺部形态变化的定量分析再次显示没有显著变化。因此，TRPA1 表达似乎既不是原发性肺上皮细胞中高氧诱导的 [Ca]水平变化的关键因素，也不是高氧诱导的肺泡上皮细胞增生所必需的。
