基质金属蛋白酶及其组织抑制剂在高氧性肺损伤中的变化

目的 探讨基质金属蛋白酶(MMPs)及其组织抑制剂(TIMPs)在高氧性肺损伤中表达及意义。方法 幼年Wistar大鼠32只,随机分为空气组和高氧组,并于高氧暴露3、7、14 d后用免疫组织化学方法(SABC)观察MMP-2、MMP-9、TIMP-1、TIMP-2在肺组织中的分布,用逆转录聚合酶链反应(RT-PCR)观察MMP-2、MMP-9、TIMP-1、TIMP-2 mRNA在肺组织中表达,此外对支气管肺泡灌洗液(BALF)中的蛋白含量、肺通透系数、肺湿／干重比(W／D)及肺组织病理学改变也进行对比分析。结果 高氧组3 d时肺组织出现水肿、出血、炎性细胞浸润,7 d时进一步加重,14 d时间质细胞增生,肺间隔明显增宽,出现肺纤维化倾向。W／D值、肺通透系数和BALF蛋白含量在3、7、14 d均明显高于空气组(P均<0.05)。免疫组化法示MMP-2、MMP-9、TIMP-1、TIMP-2在正常肺泡上皮细胞、支气管上皮细胞呈弱阳性表达,高氧组3 d时肺泡上皮细胞、支气管上皮细胞、巨噬细胞、肺泡间质细胞均呈强阳性表达,7、14 d表达更广泛。与空气组相比,高氧3 d时MMP-2、MMP-9 mRNA表达水平明显增加,7 d时最显著,14 d开始下降(P均<0.05),而TIMP-1、TIMP-2 mRNA表达却持续增加,14 d时仍无明显下降(P均<0.05)。高氧暴露后MMP-2／TIMP-2、MMP-9／TIMP-1比值亦增加,其中7 d时最为显著,14 d开始下降。结

Changes of matrix metalloproteinase and its tissue inhibitors in the lung injury induced by hyperoxia

Objective To study the significance and expressions of matrix metalloproteinase (MMPs) and its tissue inhibitors (TIMPs) in hyperoxia - induced lung injury. Methods Thirty - two juvenile Wistar rats were randomly divided into room - air group and hyperoxia group. After 3, 7, 14 days of continuous exposure to highly concentrated oxygen (>90 %), the distribution of MMP-2, MMP-9, TIMP-1 and TIMP-2 in the lung tissues were observed by immunohistochemistry and their expressions were measured by RT-PCR. In addition, lung wet/dry weight ratio, the protein content in bronchoaveolar lavage fluid(BALF), the lung permeability coefficient, histological changes were performed. Results Light microscopic findings in the hyperoxia group including edema, hemorrhage and extensive inflammatory cells in the lungs were observed. The lung wet/dry weight ratio , permeability coefficient and the protein content in BALF of hyperoxia group were much higher than those in room - air group on 3,7,14 days. Weak positive expressions of MMP-2, MMP-9, TIMP-1 and TIMP-2 were detected in alveolar and tracheal epithelial cells of room-air group, their strong expressions were observed in alveolar epithelial cells, macrophages, interstitial cells and tracheal epithelial cells of hyperoxia group. The expressions of MMP-2 and MMP-9 mRNA in the lung significantly increased after 3 days of hyperoxia exposure, then maximized on 7th but declined from the 14th day; while the expressions of TIMP-1 and TIMP-2 mRNA continuously enhanced and didn't descend so far as to the 14th day. The ratioe of MMP-2/TIMP-2,MMP-9/TIMP-l significantly enhanced after 3 days of hyperoxia exposure, then maximized on the 7th day but declined on the 14th day. Conclusions The overexpressions of MMP-2 and MMP-9 as well as the disequilibrium of MMPs/TIMPs in lung tissue play an important role in hyperoxia - induced lung injury and the development of lung fi-brosis formation.