ERK1/2与实验性慢性阻塞性肺疾病大鼠模型气道平滑肌增殖的分子机制研究

The role of ERK1/2 in airway remodeling and smooth muscle proliferation in chronic obstructive pulmonary disease

目的:探讨ERK1/2信号在烟熏实验性慢性阻塞性肺疾病大鼠模型气道重塑平滑肌增殖的分子机制。方法:取大鼠模型肺组织分别提取RNA、蛋白以及行组织病理学检查。RT-PCR检测TGF-β1、ET-1条带;Masson染色检测各组支气管管腔的内周长(Pi)、平滑肌层面积(WAm)、支气管壁面积(WAt);Western Blot检测各组标本TGF-β1、ET-1、ERK1/2和p-ERK1/2。结果:烟熏2周后气道平滑肌层和支气管壁厚度较健康对照组和U0126对照组明显增厚(P<0.05),TGF-β1、ET-1以及ERK1/2蛋白磷酸化表达均增加,予U0126干预后,气道平滑肌增殖和支气管壁厚度逐渐减轻,ERK1/2蛋白磷酸化受到抑制,呈剂量依赖性。结论:烟熏可以刺激大鼠气道平滑肌慢性炎症和平滑肌增殖,ERK1/2是COPD气道平滑肌增殖信号传导的主要途径。TGF-β1参与了ERK1/2信号系统对气道重塑平滑肌增殖的调控。MEK1的特异性阻断剂U0126能有效干预COPD气道平滑肌细胞增殖的分子信号调节。

Objective：To investigate the rote of extracellular signal-regulated kinase 1/2（ERK1/2） pathways in airway remodeling and smooth muscle proliferation by means of establishing experimental rat model of chronic obstructive pulmonary disease induced by smoking. Methods： Lung tissues of experimental rats and control rats were used to isolate RNA and protein, as well as histopathological analysis. The levels of transforming growth factor β1 （TGF-β1） and endothelin-1 （ET-1）were detected with RT-PCR. The internal perimeter of bronchi（Pi）, the area of bronchial smooth muscle （WAm）, and the total area of bronchi （WAt） were measured under Masson staining. The expressions of TGF-β1, ET-1, ERK1/2, and p-ERK1/2 in airway epithelium were analyzed by Western Blot. Results ： The thickness of airway smooth muscle and bronchial wall were significantly increased （P〈0.05） compared with healthy control group and U0126 control group after 2- week smoking. Expressions of TGF-β1, ET-1, and phosphroylation of ERK1/2 sigaling protein were also increased. Airway smooth muscle proliferation and bronchial wall thickness gradually decreased in does-dependent manner after the treatment of U0126 . ERK1/2 signaling protein phosphroylation was inhibited by U0126 in dose-dependent manner. Conclusion： Chronic inflammation and smooth muscle proliferation of rat airway can be induced by smoking. ERK1/2 pathways are the key signal transduction pathways of COPD airway smooth muscle proliferation. TGF-β1 contributes to airway remodeling and smooth muscle proliferation regulated by ERK1/2 signaling pathways. ERK 1/2 specific inhibitor U0126 can effectively intervene the molecular signaling pathways of COPD airway proliferation.