基质金属蛋白酶-9在慢性同种移植肾病早期大鼠肾组织中的表达及意义

目的研究基质金属蛋白酶9(MMP9)在慢性移植肾病早期肾组织的表达及其与转化生长因子β1(TGFβ1)表达、小管间质单个核细胞浸润及血管平滑肌细胞增殖和移行的关系。方法以雄性Fisher大鼠作供体,雄性Lewis大鼠作受体进行同种肾移植,Fisher及Lewis雄性大鼠单肾切除作对照。移植后12周作肾功能、移植肾组织学检测,应用免疫组织化学方法测定肾组织中MMP9及TGFβ1子的表达,应用逆转录聚合酶链反应(RTPCR)方法检测肾组织MMP9mRNA表达水平及β肌动蛋白mRNA的表达。结果实验组大鼠12周时24h尿蛋白定量(g/d)0.025±0.028,与F344、Lewis对照组间24h尿蛋白水平差异无统计学意义;血清肌酐(μmol/L)96±36,显著高于F344组,与Lewis组比较差异无统计学意义;肌酐清除率(ml·min-1·100g体重-1)0.18±0.10,三组间差异无统计学意义。实验组大鼠肾动脉血管壁及肾间质MMP9(分别为0.095±0.020,0.32±0.09)与TGFβ1蛋白表达水平(分别为0.086±0.017,0.58±0.10)及肾组织MMP9mRNA表达水平(1.34±1.06)均显著高于对照组。相关分析结果显示,肾组织MMP9mRNA表达水平与间质单个核细胞浸润程度呈显著正相关,肾组织MMP9蛋白表达水平与间质中单个核细胞数量、血管平滑肌细胞数量、肾组织TGFβ1蛋白表达水平均呈显著正相关。结论MMP9在慢性移植肾病早期的病理变化中发挥关键性的作用,其产生机制与TGFβ1表达增强有关。

Expression of matrix metalloproteinase-9 in renal tissues of rats with chronic allograft nephropathy at early stage and the role thereof

OBJECTIVE: To investigate the expression of matrix metalloproteinase-9 (MMP-9) in the renal tissues of rats with chronic allograft nephropathy (CAN) at early stage and its role in CAN. METHODS: Orthotopic transplantation of left kidney was performed between 10 male LEW rats and 10 male F344 rats with the formers as recipients. Small dose cyclosporin A was used to suppress acute rejection. Ten days after the operation the right kidneys of the recipients were resected. Ten LEW rats and 10 F344 rats with their single kidneys resected were used as controls. Twelve weeks after the operation the rats were harvested to take out the transplanted kidneys to undergo histologic examination. Immunochemistry was used to examine the expression of MMP-9 protein and transforming growth factor (TGF)-beta1 . RT-PCR was used to examine the expression of MMP-mRNA in the kidney tissues. At the same time 24 h urine samples were collected to examine the urinary protein. The relationship between the expression of MMP-9 and TGF-beta1 and the quantity of SMCs and mononuclear cells. RESULTS: The 24 h urinary protein level of the experimental group was not significantly different from those of the F3244 control group and LEW control group. The serum inosine level of the experimental group was significantly higher than that of the F334 control group and was not significantly different from that of the LEW control group. The degrees of pathologic change degree (Banff score) and fibrosis of kidney interstitium, and the number of inflammatory cells infiltrating into tubulointerstitium, arterial smooth muscle cells (SMCs) in renal cortex, and SMCs in vascular wall of the experimental group were all significantly higher than those of the 2 control groups. The expressions of MMP-9 protein and TGF-beta1 in the kidney interstitium and vascular wall and the expression of MMP-9 mRNA were all significantly higher than those of the 2 control groups. The expression of MMP-9 mRNA in kidney tissues was positively correlated with the degree of infiltration of interstitial mononuclear cells. The MMP-9 mRNA expression level was positively correlated with the number of interstitial mononuclear cells. The MMP-9 protein expression level was positively correlated with the TGF-beta1 expression level in the tubulointerstitium and in the renal arterial wall. CONCLUSION: MMP-9 plays a key role in CAN at early stage. Its expression may be induced by TGF-beta1.