肺纤维化形成中整合素相关激酶的表达与上皮-间充质细胞转化

EXPRESSION OF INTEGRIN-LINKED KINASE AND EPITHELIAL-MESENCHYMAL TRANSITION IN THE FORMATION OF PULMONARY FIBROSIS

目的观察整合素相关激酶(ILK)在博莱霉素致小鼠肺纤维化中的动态表达,探讨其在肺纤维化中与上皮-间充质细胞转化(EMT)的关系。方法将32只小鼠随机分成正常对照组,博莱霉素(BLM)致肺纤维化组。后者以博莱霉素腹腔注射致肺纤维化,正常对照组仅在相同处理条件下注射生理盐水。治疗的第28天和40天处死动物取出肺组织,用苏木精-伊红(HE)和Massontrichrome染色,分别观察实验动物肺炎症和纤维化的程度,以样本碱水解法检测肺组织中羟脯氨酸的量,逆转录-聚合酶链反应(RT-PCR)检测ILK mRNA表达、免疫组化检测不同实验组小鼠ILK,并同时检测间充质细胞标记物α-平滑肌肌蛋白(α-SMA)和上皮细胞标记物上皮钙粘附素(E-Cad)的表达。结果组织学结果显示小鼠肺组织胶原含量在第28d明显增加,第40d达高峰,羟脯氨酸测定动态增高。与正常对照组比较,肺纤维化组中ILK、α-SMA蛋白表达增高(P<0.01),E-Cad的蛋白表达降低(P<0.01)。RT-PCR结果显示肺纤维化组ILKmRNA的表达显著增高(P<0.01)。ILK的表达不仅与羟脯氨酸的含量成正相关(r分别为0.867、0.886,P均小于0.05),也与α-SMA/E-Cad比值成正相关(r分别为0.830、0.844,P均小于0.05);α-SMA与E-Cad成负相关(r分别为-0.820、-0.833,P均小于0.05)。结论ILK在小鼠肺纤维化中表达与纤维化的程度呈正相关增高,表明其可能是肺纤维化形成的促进因子,且由于ILK与α-SMA/E-Cad比值成正相关,推测ILK在肺纤维化形成中的机制可能与促进EMT有关。

Objective To investigate the developing expression of Integrin-linked kinase （ILK） and its relation to epithelial-mesenchymal transition in bleomycin-induced pulmonary fibrosis in mice. Methods Thirty-two mice were randomly divided into the control group and the model group. The mice in the model group received bleomycin injected intraperitoneally to induce pulmonary fibrosis, while the other group received an equivalent volume of saline alone administered in the same manner. All mice were killed on days 28 and 40 after treatment. Lung tissue was stained with HE and Masson-trichrome method. Lung hydroxyproline （HP） content was evaluated. ILK mRNA was analyzed by RT-PCR. Immunohistochemistry and image analysis were used to detect the expression of ILK, alpha-smooth muscle actin （α-SMA） and E-cadherin. Results Collagen deposition was increased evidently on days 28, and peaked on days 40. Lung hydroxyproline （HP） content was increased gradually. Compared to those in the control group, the protein level of ILK and α-SMA was significantly increased in the model group （P 〈 0. 01 ） , while the protein level of E-cadherin was decreased significantly （P 〈0.01 ） , and the mRNA level of ILK was also increased significantly （P 〈0.01 ） . A significant positive correlation was found not only between the expressions of ILK and HP content （ r = 0. 867 and P 〈 0.05, r = 0. 886 and P 〈 0. 05, respectively） , but also be- tween the expression of ILK and α-SMA/E-Cad （r =0. 830 and p 〈0. 05, r =0. 844 and P 〈0. 05, respectively） . There was a negative correlation between the expressions of α-SMA and E-Cad （ r = -0. 820 and P 〈 0. 05, r - - 0. 833 and P 〈 0.05, respectively） . Conclusion The expression of ILK is positively correlated with not only the degree of pulmonary fibrosis but also the level of α-SMA/E-Cad, which probably suggests that ILK is a promoter to pulmonary fibrosis via the induction of epithelial-mesenchymal transition.