表皮生长因子受体在臭氧致呼吸道炎症过程中的作用及其机制

Ozone is currently a major air pollutant in China. Short-term inhalation of high levels of ozone could result in airway inflammation. We have recently observed that acute exposure to ozone could activate EGF receptor (EGFR) on human bronchial epithelial cells, and pharmacological inhibition of EGFR markedly suppressed ozone-induced over-expression of chemokine IL8. Therefore, we assumed that EGFR may play a critical role in ozone-induced airway inflammation. The aims of this study are to reveal the mechanisms underlying ozone-induced EGFR activation and the regulatory effect of EGFR on ozone-induced inflammatory responses of primary human bronchial epithelial cells and airway inflammation in mice. The in vitro studies will be performed to characterize the involvement of oxidative stress and cytosolic tyrosine kinase Src in ozone-induced EGFR activation, and the regulatory effect of EGFR on ozone-induced cellular inflammatory responses. The animal study will determine the phosphorylation of EGFR in airway epithelium of mice exposed to ozone and the role of EGFR in ozone-induced airway inflammation. This study is expected to provide essential evidence for elucidation of mechanisms of ozone-induced airway inflammation.

臭氧是目前我国一种主要空气污染物。短期吸入高浓度臭氧可引起呼吸道炎症。申请人最近发现臭氧短期刺激可激活人支气管上皮细胞表皮生长因子受体（EGFR）；EGFR抑制剂可明显降低臭氧所致炎性细胞趋化因子白介素8（IL8）的表达。因此推测EGFR可能在臭氧所致呼吸道炎症过程中发挥重要作用。本研究目的旨在阐明臭氧激活EGFR的机制和EGFR在臭氧诱发呼吸道炎症中的作用。体外研究将以人支气管上皮细胞气液分界培养系统为模型，揭示氧化应激和蛋白激酶Src在臭氧诱发EGFR活化过程中的作用与EGFR调节臭氧所致的体外细胞炎性反应；体内实验则重点检测吸入臭氧小鼠呼吸道上皮细胞EGFR的磷酸化及EGFR在臭氧所致呼吸道炎症中的作用。本研究将为阐明臭氧所致呼吸道炎症机制提供重要实验依据。

我国大气污染已经从煤烟型污染转变为复合型污染，以高水平臭氧为特征的光化学污染日益严重。流行病学调查发现，暴露高浓度臭氧可诱发呼吸道炎症。然而，臭氧诱发呼吸道炎症的机制尚未完全阐明。本研究目的是阐明臭氧对呼吸道炎性作用及其机制。体外研究结果显示，臭氧(0.25-1.0 ppm) 暴露可诱导人支气管上皮细胞EGF受体（EGFR）第845和1068位酪氨酸快速磷酸化；还可诱导胞浆Src激酶活化。Src激酶抑制剂能显著降低臭氧对EGFR的磷酸化作用。此外，EGFR和Src激酶抑制剂均可明显抑制臭氧对趋化因子白介素8表达的诱导作用。提示Src/EGFR信号通路在臭氧诱导呼吸道上皮炎性反应中发挥重要作用。体内实验结果显示，BALB/c小鼠吸入1ppm臭氧，肺脏发生明显炎性改变，表现为暴露组小鼠肺灌洗中总蛋白、活性氧、EGF、TGFa以及趋化因子（CXCL1）水平明显升高以及肺组织炎性病理改变；呼吸道上皮EGFR（Y1068）磷酸化水平升高。小鼠呼吸道预灌注EGFR抑制剂，可明显降低臭氧所致的炎性作用。综上所述，本研究揭示EGFR在臭氧所致呼吸道炎性改变过程中发挥重要作用。这为阐明臭氧的毒作用机制以及设计干预措施提供了重要实验依据。