• Xiang-feng Zhang, Guang-fa Zhu, Shuang Liu, and Hussein D Foda.
• Department of Pulmonary Medicine, Beijing Anzhen Hospital Affiliated by Capital Medical University, Beijing 100029, China. xfzh20008@yahoo.com.cn
• Zhongguo Wei Zhong Bing Ji Jiu Yi Xue. 2008 Oct 1;20(10):597-600.

ObjectiveTo investigate the role of matrix metalloproteinase-2/9 (MMP-2/9) and their tissue inhibitors (TIMP-1/2) in pathogenesis of acute lung injury (ALI) induced by hyperoxia.MethodsSeventy-two C57BL/6 mice were randomly divided into normal control group, hyperoxia for 24 hours group, hyperoxia for 48 hours group, and hyperoxia for 72 hours group, with 18 mice in each group. The mice in hyperoxia groups were exposed to >98% oxygen in sealed cages, and the normal control group were placed outside of the cage to breathe room air. At the end of the exposure time the animals were euthanized, the right lung was removed and phosphate buffer solution (PBS) was used to lavage the lung through the endotracheal catheter. The wet/dry weight ratio, broncho-alveolar lavage fluid (BALF) protein content and the volume of pleural fluid were measured, the severity of lung injury was assessed; the expression of MMP-2/9 and TIMP-1/2 mRNA in lung tissue at 24, 48 and 72 hours of hyperoxia were assessed by reverse transcript-polymerase chain reaction (RT-PCR); the amount of MMP-2/9 and TIMP-1/2 protein in lung tissue were measured by enzyme-linked immunosorbent assay (ELISA).ResultsHyperoxia caused ALI as evidenced by the increase in lung wet/dry weight ratio, BALF protein content and the volume of pleural fluid as compared with the normal control group (P<0.05 or P<0.01). RT-PCR study showed increased expression of MMP-2/9 and TIMP-1 mRNA in lung tissues (P<0.05 or P<0.01), and ELISA assay also demonstrated upregulation of MMP-2/9 and an increase in TIMP-1 amount in BALF compared with their normal control group (P<0.05 or P<0.01). The ratios of both MMP-2 mRNA/TIMP-2 mRNA and MMP-2 protein/TIMP-2 protein were all increased in hyperoxia groups as compared with their normal control group (all P<0.01).ConclusionHyperoxia causes ALI in mice, and disturbance of MMP-2/TIMP-2 balance plays an important role in the development of hyperoxia-induced ALI in mice.

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