实验性肺纤维化大鼠肺组织Cathepsin B表达的动态变化

Dynamic changes of CB expression in lungs of rats with experimental pulmonary fibrosis

目的探讨溶酶体组织蛋白酶B(cathepsinb,CB)在肺纤维化发病中的作用。方法应用博莱霉素(5mg/kg)气管内注入建立实验性大鼠肺纤维化模型,采用HE染色、Masson三联染色、免疫组织化学染色、RT-PCR等方法,观察实验性大鼠肺纤维化的发病过程及其肺组织中CathepsinB蛋白及mRNA表达水平的动态变化。结果实验性大鼠肺纤维化发病过程中,呈现典型的肺泡炎(7d)、纤维组织增生(14d)及稳定的肺纤维化(28～35d)等表现;CathepsinB在正常肺组织表达较弱,在肺纤维化组7d时表达增强,14d进一步增强,28d明显增强,35d时较28d开始减弱,但仍强于正常组;CathepsinBmRNA在正常肺组织中表达较弱,在肺纤维化组7d时表达增强,14d进一步增强,28d明显增强,35d时较28d开始减弱,但仍强于正常组。结论CathepsinB在实验性大鼠肺纤维化发病过程中起重要作用,其过度表达可能参与了肺纤维化的发生发展过程。

[Objective] To investigate the role of CB protein in the pathogenesis of experimental pulmonary fibrosis. [Methods] 48 male SD rats were randomly divided into two groups, the pulmonary fibrosis group and the control group. Rat pulmonary fibrosis was reproduced by an intratracheal injection of bleomycin （5 mg/kg body weight）. Normal saline （1 mL/kg body weight）was given intratracheally injection in the control group. There were 24 rats in each group, and 6 animals were separately killed on the 7 th, 14 th, 28t h and 35 th day after treated with bleomycin or normal saline. Then the following tests were undertaken： HE and Masson staining of lung section; Immunohistochemical staining of protein of CB in the lung; RT-PCR of CB mRNA in the lung. [Results] ①There were full of inflammatory cells in the lung, and the interval of alveoli enlarged and many alveolar spaces disappeared on the 7 th day after treated with bleomycin in the fibrosis group. Collagen began to proliferate after 14 d. The pulmonary fibrosis was stably established on day 28-35, full of green fibers in the Masson staining of lung section.②The expression of CB protein in the lung increased after 28 d in bleomycin-treated animals [（29.76±4.62） vs （78.48±5.36）, P 〈0.01 vs control], but slightly increased on the 7th day （68.52±1.56） and expensively increased on the 14 st day （48.82±4.97） and the 35 th day （46.76±4.70）. ③The expression of CB mRNA in the lung also increased after 7 d by treated with bleomycin [（0.5933±0.0200）vs（0.4290±0.0292）, P 〈0.01 vs control], increased on the 14 th day （0.6713±0.0117） and further increased on the 28 th day （0.9680±0.0142）, but decreased on the 35 th day （0.6827±0.0309）. The expression of CB protein and mRNA in fibrosis group was higher than that in the control group （P〈0.05 or P〈0.01）. [Conclusion] Cathepsin B protein and Cathepsin B mRNA are dynamically changed in the lung with experimental pulmonary fibrosis, which may contribute to the pathogenesis of pulmonary fibrosis.