急性肺损伤MMP-2mRNA变化及地塞米松的保护作用

The expression of MMP - 2 mRNA in endotoxin - induced acute lung injury and the protective effects of dexamethasone

目的 探讨内毒素（ET）致急性肺损伤（ALI）肺组织中基质金属蛋白酶-2（MMP-2）的变化，以及地塞米松对其水平的影响。 方法 24只3个月龄日本大耳白兔被随机分为生理盐水组（A组），ET损伤组（B组），地塞米松预处理＋ET损伤组（C组）。B组静脉注射ET 700 μg/kg以复制ALI模型，C组在ET静脉注射前给予5 mg/kg地塞米松进行预处理，监测氧合指数（PaO2/FiO2）、肺组织中MMP-2 mRNA的表达情况。 结果 B组PaO2/FiO2于实验0.5 h降至最低（265.4±70.2） mm Hg，随后出现升高；肺水含量（0.813±0.009）%与肺组织MMP-2 mRNA表达（0.941±0.019）与A组［（0.787±0.005）%，0.608±0.015］比较明显增加（P〈0.01）；光镜下观察肺组织出现水肿、出血、炎症细胞浸润。C组PaO2/FiO2未见明显下降；肺组织肺水含量（0.788±0.012）%与MMP-2 mRNA表达（0.654±0.013）较B组明显减少（P〈0.01）；肺组织水肿、出血、炎症细胞浸润情况较B组轻。 结论 地塞米松可以通过抑制肺组织中MMP-2 mRNA的表达，在一定程度上对ET致ALI产生保护作用。

Objective To explore the effect dexamethasone on the expression of matrix metalloproteinase- 2 （MMP- 2 ） mRNA in lungs in endotoxin （ET） -induced acute lung injury （ALl）. Methods 24 flap - eared white rabbits were randomly assigned to 3 groups with 8 rabbits in each group ： saline group （ group A）, ET - induced group （ group B ） , dcxamethasone pretreatment ＋ ET group （group C）. The rabbits were injected with endotoxin （700 μg/kg） to induce the model of ALI. The rabbits were injected with dexamethasone （5 mg/kg ） before giving ET. The arterial blood oxygenation index （PaO2/FiO2 ） , lung water content, the expression of MMP -2 mRNA in lung tissue were observed. Results PaO2/FiO2 in group B decreased significantly at 0.5 h （265.4 ± 70. 2） mm Hg） , then gradually increased. The lung water content （0. 813 ± 0. 009）% and the expression of MMP-2 mRNA （0. 941 ±0. 019） in the lung of group B were more significantly increased than those [ （0.787 ±0. 005 ） % ,0.608 ± 0. 015 ] in group A. The lung edema, hemorrhage, and inflammatory cell infiltration were observed in group B. There was no significant decrease in PaO2/FiO2 in group C. Lung water content（0. 788 ± 0. 012） % and the expression of MMP - 2 mRNA （0.654 ±0. 015） in lung tissue were significantly lower than those in group B. The edema, hemorrhage and inflammatory cell infiltration of lung tissue were lighter than those in group B. Conclusion Dexamethasone can protect endotoxin - induced ALI by inhibiting the expression of MMP -2 mRNA.