基质金属蛋白酶-2及其抑制物-2在高氧致慢性肺疾病新生大鼠肺组织中的动态变化及意义

The changes and effects of metalloproteinase-2 and tissue inhibitors of metalloproteinase-1 protein and mRNA expression in the lung tissue of neonatal rats with chronic lung disease induced by hyperoxia

目的探讨基质金属蛋白酶-2（MMP-2）及其抑制物-2（TIMP-2）mRNA和蛋白在高氧致慢性肺疾病（CLD）新生大鼠肺组织中的动态表达规律以及在CLD发生中的作用和意义。方法足月新生大鼠出生后12h内分别持续吸入0．90～0．95的高氧或空气，于1、3、7、14和21d取肺组织进行苏木素-伊红（HE）染色，辐射状肺泡计数（RAC）；用免疫组化和逆转录-聚合酶链反应（RT-PCR）方法分别检测肺组织MMP-2和TIMP-2的蛋白及mRNA表达。结果病理观察高氧组早期炎症反应，7d出现肺泡发育阻滞，最终纤维化；在7d时高氧组RAC值较空气组降低（P〈0．05），14d和21d的差异更为显著（P均〈0．01）；在高氧暴露3d时，MMP-2的蛋白和mRNA表达均较空气组增强（P〈0．05和P〈0．01），14d时MMP-2蛋白表达减弱（P〈0．05），而mRNA水平两组间差异无统计学意义；TIMP-2的蛋白和mRNA表达在两组中各时间点比较差异均无统计学意义。结论高氧暴露后，肺组织中MMP-2／TIMP-2表达失衡，使细胞外基质降解异常，可能是高氧致肺早期炎性损伤和最终肺间质纤维化及发育障碍的机制之一。

Objective To investigate the dynamic changes and the effects of metalloproteinase-2 （MMP-2） and tissue inhibitors of metalloproteinase-2 （TIMP-2） mRNA in lungs of neonatal rats after inhaling high concentration of oxygen. Methods Full-term newborn rats were continuously exposed to oxygen （0.90- 0.95） or room air （0.21O2） within 12 hours after.birth. Lung histological study with hematoxylin-eosin staining （HE） and radical alveolar counts （RAC） were performed; the changes in MMP-2 and TIMP-2 protein and mRNA expression were measured by immunohistochemistry and reverse transcription-polymerase chain reaction （RT-PCR） on 1. 3, 7, 14 and 21 days in hyperoxia groups and air inhalation controls. Results Compared with air inhalation controls, inflammation response was seen in early stage, the arrest of lung development was evident after 7 days of oxygen exposure, finally resulting in interstitial fibrosis; RAC began to decrease from 7 days in hyperoxia rats compared to air inhalation controls （P〈0. 05）, more so on 14 days and 21 days （both P0. 01）; MMP-2 protein and mRNA expression were higher on 3 days （P〈0. 05 and P〈0. 01）, and protein decreased on 14 days （P〈0. 05）, while mRNA didn＇t change; the expression of TIMP-2 protein and mRNA showed no change all the time. Conclusion With prolonged hyperoxia, the balance of MMP-2/ TIMP-2 can not be maintained. Collagen breakdown is disturbed, which may lead to lung inflammatory injury in early stage and then collagen deposition in lung interstitium and lung development is arrested resulting in chronic lung disease.