地塞米松预处理对大鼠光气吸入性肺损伤基质金属蛋白酶-9表达的影响

目的 探讨地塞米松对大鼠光气吸入性急性肺损伤(ALI)基质金属蛋白酶-9(MMP-9)表达的影响.方法 将SD大鼠随机分为3组:正常对照组(吸入与光气染毒组同等流量的空气)、光气染毒组(吸入8.33 mg/L的光气)、地塞米松预处理组(尾静脉注入2.5 mg/kg地塞米松1 h后,吸入8.33 mg/L的光气).染毒2 h后,收集支气管肺泡灌洗液(BALF)测定中性粒细胞细胞数、蛋白含量和肺湿/干重比(W/D).用放射免疫法测定各组血清和BALF中MMP-9水平.进行肺组织的病理学检查,用免疫组化法和实时定量聚合酶链反应(PCR)测定MMP-9表达的变化.结果 与染毒组比较,预处理组大鼠肺W/D、BALF中中性粒细胞数和蛋白含量明显降低,差异有统计学意义(P＜0.01).与染毒组血清:(9.439±0.100)μg/L、BALF:(20.640±0.446)μg/L]比较,预处理组MMP-9含量血清(4.799±0.043)μg/L、BALF:(15.052±0.029)μg/L]明显降低,差异有统计学意义(P＜0.01).与染毒组(2.789±0.282)比较,预处理组MMP-9mRNA的表达量(1.183±0.260)明显降低,差异有统计学意义(P＜0.01).染毒组肺泡壁明显充血、增厚,肺泡壁和肺间质内可见较多白细胞浸润以及肺泡结构破坏;预处理组肺泡结构较为清晰,肺泡壁稍增厚,伴少量炎性细胞浸润.正常对照组大鼠肺、支气管组织中MMP-9蛋白表达呈弱阳性,染毒组MMP-9蛋白表达呈强阳性,预处理组肺、支气管组织中MMP-9蛋白表达明显减弱.结论 地塞米松能有效地保护大鼠光气吸入性ALT,可能通过抑制MMP-9表达而达到肺保护作用.

Abstract：

Objective To investigate the effects of dexamethasone on expression of matrix metalloproteinase-9 (MMP-9) in rats with acute lung injury induced by phosgene. Methods The rats were randomly divided into 3 groups: normal control group that consists of the rats with air exposure, phosgene group that consists of the rats with phosgene exposure and dexamethasone group that consists of the rats with phosgene exposure after 2.5 mg/kg dexamethasone being injected. Wet and dry ratio of the lung (W/D) was calculated, and leukocyte count and total protein content of bronchoalveolar lavage fluid (BALF) were recorded at 2 h after exposure. The concentrations of MMP-9 in the serum and BALF were measured by enzyme-linked immunosorbent assay. The pathologic changes of lung tissues were observed under light microscopy. The immunohistochemistry and the RT-PCR were used to detect the contents of MMP-9 in the lung tissue. Results Compared with phosgene group, the lung W/D, protein content and WBC count in of BALF dexamethasone group was significantly decreased (P＜0.01). MMP-9 levels of the serum and BALF in dexamethasone group were (4.799±0.043) μg/L and (15.052±0.029) μg/L, respectively, which were significantly lower than those (9.439±0.100) and (20.640±0.446) μg/L] in phosgene group (P＜0.01). Compared with phosgene group (2.789±0.282), the expression level(1.183±0.260) of lung M MP-9 mRNA in dexamethasone group was significantly lower than that in phosgene group (P＜0.01).Histological experimental results showed the marked hyperemia and thickening of alveolar wallsand stroma cells infiltrating and more visible alveolar structure damage of alveolar walls in phosgene group while the alveolar structure and the alveolar walls were clear and slightly thickened with inflammatory cells in dexamethasone group. Immunohistochemical results showed that MMP-9 protein expression levels of lung and brochus tissues in normal control group and dexamethasone group were weakly positive, which in phosgene group were strongly positive. Conclusion Dexamethasone has a beneficial effects on acute lung injury induced by phosgene in rats due to the inhibiting MMP-9.

Effects of dexamethasone pretreatment on expression of matix metalloproteinase-9 in rats with acute lung injury induced by phosgene

Objective To investigate the effects of dexamethasone on expression of matrix metalloproteinase-9 (MMP-9) in rats with acute lung injury induced by phosgene. Methods The rats were randomly divided into 3 groups: normal control group that consists of the rats with air exposure, phosgene group that consists of the rats with phosgene exposure and dexamethasone group that consists of the rats with phosgene exposure after 2.5 mg/kg dexamethasone being injected. Wet and dry ratio of the lung (W/D) was calculated, and leukocyte count and total protein content of bronchoalveolar lavage fluid (BALF) were recorded at 2 h after exposure. The concentrations of MMP-9 in the serum and BALF were measured by enzyme-linked immunosorbent assay. The pathologic changes of lung tissues were observed under light microscopy. The immunohistochemistry and the RT-PCR were used to detect the contents of MMP-9 in the lung tissue. Results Compared with phosgene group, the lung W/D, protein content and WBC count in of BALF dexamethasone group was significantly decreased (P＜0.01). MMP-9 levels of the serum and BALF in dexamethasone group were (4.799±0.043) μg/L and (15.052±0.029) μg/L, respectively, which were significantly lower than those (9.439±0.100) and (20.640±0.446) μg/L] in phosgene group (P＜0.01). Compared with phosgene group (2.789±0.282), the expression level(1.183±0.260) of lung M MP-9 mRNA in dexamethasone group was significantly lower than that in phosgene group (P＜0.01).Histological experimental results showed the marked hyperemia and thickening of alveolar wallsand stroma cells infiltrating and more visible alveolar structure damage of alveolar walls in phosgene group while the alveolar structure and the alveolar walls were clear and slightly thickened with inflammatory cells in dexamethasone group. Immunohistochemical results showed that MMP-9 protein expression levels of lung and brochus tissues in normal control group and dexamethasone group were weakly positive, which in phosgene group were strongly positive. Conclusion Dexamethasone has a beneficial effects on acute lung injury induced by phosgene in rats due to the inhibiting MMP-9.