多器官功能障碍综合征大鼠肺组织MMP-9、TIMP-1和Ⅳ型胶原的表达

目的:检测基质金属蛋白酶9(MMP-9)、金属蛋白酶组织抑制物1(TIMP-1)和Ⅳ型胶原(Ⅳ-C)在多器官功能障碍综合征(MODS)大鼠肺组织中表达的变化,探讨MODS肺损伤的发生机制。方法:将40只成年雄性SD大鼠随机分为假手术对照组和盲肠结扎穿孔(CLP)模型组,其中,CLP组又根据造模后不同时点分为MODS 6 h组、MODS 12 h组、MODS 24 h组和MODS 48 h组,每组各8只。采用改良的CLP法构建MODS大鼠模型,于造模后不同时点处死大鼠并收集标本。血液生化检查及血气分析检测各组大鼠肝、肾和肺功能的情况,HE染色观察肺组织形态学改变,ELISA法检测血清中肿瘤坏死因子α(TNF-α)、白细胞介素-1β(IL-1β)、MMP-9及TIMP-1含量的变化,RT-PCR和免疫组织化学法检测肺组织MMP-9及TIMP-1表达的变化,免疫荧光和Western blot法检测肺组织Ⅳ-C表达的变化。结果:与对照组比较,MODS各组均出现不同程度的肝、肾和肺功能损伤。光镜下对照组肺组织结构无明显改变,模型组肺组织损伤较重。与对照组比较,各模型组血清中TNF-α、IL-1β、MMP-9及TIMP-1的含量均明显升高(P0.05),于造模后12~24 h达高峰(P0.01)。各模型组肺组织MMP-9和TIMP-1表达明显高于对照组,MMP-9于造模后12 h达高峰(P0.01),TIMP-1于造模后24 h达高峰(P0.01)。与对照组比较,造模后6 h肺组织Ⅳ-C降低不明显,12~48 h显著下降,于24 h降至最低(P0.01)。结论:MMP-9和TIMP-1通过共同调节细胞外基质主要成分Ⅳ-C的合成和分解,在MODS肺损伤中发挥重要作用。

Expression of matrix metalloproteinase-9, tissue inhibitor of metalloproteinase-1 and collagen type IV in lung of rats with multiple organ dysfunction syndrome

AIM: To determine the expression of matrix metalloproteinase-9 (MMP-9), tissue inhibitor of me-talloproteinase-1 (TIMP-1) and collagen type IV (IV-C) in the lung of rats with multiple organ dysfunction syndrome (MODS) and to investigate the mechanism of lung injury in MODS. METHODS: Adult male Sprague-Dawley (SD) rats (n=40) were randomly divided into sham control group and cecal ligation and puncture (CLP) model group. The rats in CLP group were divided into 4 subgroups as different intervals (6 h, 12 h, 24 h and 48 h), and there were 8 rats in each group. The rat model of MODS was established by CLP. All rats were sacrificed at various intervals. The functions of the liver, kidney and lung were determined by blood biochemical and blood gas analysis. The morphological changes of the lung tissues were observed with HE staining. The serum levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, MMP-9 and TIMP-1 were measured by ELISA. The expression of MMP-9 and TIMP-1 in the lung tissues was detected by RT-PCR and immunohistochemistry, and the expression of IV-C in the lung tissues was detected by immunofluorescence and Western blot. RESULTS: Compared with sham control group, the functions of the liver, kidney and lung were damaged at different degrees in model groups. No histopathological change in the lung tissues of sham control group was found, and the lung injury was serious in model groups. Compared with sham control group, the serum levels of TNF-α, IL-1β, MMP-9 and TIMP-1 in model groups increased significantly (P<0.05) and peaked at the interval of 12~24 h after modeling (P<0.01). The expression of MMP-9 and TIMP-1 in the lung tissues of model groups increased, and peaked at 12 and 24 h, respectively (P<0.01). The protein level of IV-C in MODS 6 h group was not changed as compared with control group, while that at the interval of 12~48 h after modeling was significantly decreased and dropped to the lowest at 24 h (P<0.01). CONCLUSION: MMP-9 and TIMP-1 play important roles in lung injury of MODS rats by regulating the synthesis and decomposition of IV-C which is the main component of extracellular matrix.