Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198-5800, USA.
Am J Respir Cell Mol Biol. 2011 Oct;45(4):882-8. doi: 10.1165/rcmb.2010-0419OC. Epub 2011 Mar 25.
A subset of workers in swine confinement facilities develops chronic respiratory disease. An aqueous extract of dust from these facilities (hogbarn dust extract [HDE]) induces IL-6 and IL-8 release and several other responses in isolated airway epithelial cells. The cell membrane receptors by which HDE initiates these responses have not been identified. Because several other inhaled agents induce airway epithelial cell responses through epidermal growth factor receptor (EGFR) activation, we hypothesized that HDE would activate EGFRs and that EGFRs would be required for some of the responses to HDE. Exposure of Beas-2B cells to HDE caused EGFR phosphorylation and downstream ERK activation, and both responses were blocked by the EGFR-selective kinase inhibitor AG1478. AG1478 and EGFR-neutralizing antibody reduced HDE-stimulated IL-6 and IL-8 release by about half. Similar EGFR phosphorylation and requirement of EGFRs for maximal IL-6 and IL-8 release were found with primary isolates of human bronchial epithelial cells. Because HDE-stimulated IL-6 and IL-8 release involve the Ca(2+)-dependent protein kinase Cα, we hypothesized that HDE would induce intracellular Ca(2+) mobilization. HDE exposure induced intracellular Ca(2+) mobilization in Beas-2B cells and in primary cell isolates, but this response was neither mimicked by EGF nor inhibited by AG1478. Thus, HDE activates EGFRs and their downstream signaling, and EGFR activation is required for some but not all airway epithelial cell responses to HDE.
猪舍工人中有一部分会患上慢性呼吸道疾病。这些工厂（猪圈粉尘提取物[HDE]）的粉尘水溶液会引起气道上皮细胞释放白细胞介素-6（IL-6）和白细胞介素-8（IL-8），并引发其他一些反应。但到目前为止，还没有发现 HDE 引发这些反应的细胞膜受体。由于其他几种吸入性物质通过表皮生长因子受体（EGFR）的激活引发气道上皮细胞的反应，因此我们假设 HDE 会激活 EGFR，而 EGFR 是气道上皮细胞对 HDE 做出某些反应所必需的。Beas-2B 细胞暴露于 HDE 会导致 EGFR 磷酸化和下游 ERK 的激活，而 EGFR 选择性激酶抑制剂 AG1478 可以阻断这两种反应。AG1478 和 EGFR 中和抗体使 HDE 刺激的 IL-6 和 IL-8 释放减少了约一半。用原代人支气管上皮细胞进行的类似实验也发现了 EGFR 磷酸化和 EGFR 对最大 IL-6 和 IL-8 释放的需求。由于 HDE 刺激的 IL-6 和 IL-8 释放涉及钙依赖性蛋白激酶 Cα，我们假设 HDE 会诱导细胞内 Ca2+的动员。HDE 暴露会引起 Beas-2B 细胞和原代细胞系中细胞内 Ca2+的动员，但 EGF 既不能模拟也不能被 AG1478 抑制这种反应。因此，HDE 激活 EGFR 及其下游信号通路，EGFR 的激活是气道上皮细胞对 HDE 做出某些反应所必需的，但不是全部。
