幼鼠残肾组织凝血酶敏感蛋白-1介导凝血纤溶与肾纤维化的相关研究

Correlation between thrombospondin-1 mediated thrombofibrinolysis and tubulointerstitial fibrosis in remnant renal tissues of 5/6 nephrectomized young rats

目的探讨在幼年性慢性进展性肾脏病不同时间点肾组织凝血酶敏感蛋白(TSP)-1表达对肾组织凝血纤溶系统的影响,及其与肾纤维化的相关性。并探讨血管紧张素转换酶抑制剂(ACEI)的干预作用。方法用5/6肾切除残肾幼年大鼠为模型,分为不治疗组、治疗组、假手术组。于实验开始,4、8、12周为时间点,检测体质量、血压、尿蛋白定量(24h)等。用免疫组织化学法检测TSP-1、血浆凝血酶原激活物抑制物(PAI)-1、转化生长因子(TGF)-β1、尿激酶型纤溶酶原激活物(uPA)、组织型纤溶酶原激活物(tPA)的表达趋势。分析上述指标在病变进展过程中的变化特点及相关性。判断ACEI的干预效果。结果不治疗组残肾组织中tPA和uPA的表达较假手术组减少,PAI-1的表达增加。治疗后大鼠残肾组织中tPA、uPA表达明显增加,PAI-1表达明显减少。5/6肾切除大鼠各组残肾组织中TSP-1和TGF-β1的表达较假手术组上调,且呈同步上调趋势,治疗组TSP-1和TGF-β1表达则明显趋于下调,治疗组残肾组织TSP-1表达在组织定位上与肾小球硬化和肾小管间质纤维化趋势呈正相关,TSP-1表达与TGF-β1和PAI-1表达呈明显正相关,与uPA和tPA表达呈负相关。结论TSP-1和TGF-β1是促进肾纤维化的重要因子,TSP-1高表达通过影响tPA、uPA、PAI-1及其平衡导致肾组织凝血纤溶系统平衡发生紊乱而促进病变发展。

Objective To investigate how thrombospondin-1 （TSP-1） expression affects and correlates to the thrombofibrinolysis during progression of chronic renal lesions or tubulointerstitial fibrosis in remnant renal tissues of 5/6 nephrectomy young rats, and to study the efficacy of intervention with angiotensin converting enzyme inhibitor （ACEI）. Methods Five sixths nephrectomized （5/6 NX） young rats were used as a classical chronic renal failure model. The rats were randomized into the untreated NX group, ACEI-treated NX group or sham group. At the start of this experiment and at weeks 4, 8 and 12, body weight, blood pressure and 24 h proteinuria of the rats were measured protein expressions of TSP-1, PAI-1, TGF-β1, uPA and tPA in remnant renal tissues were determined using immunohistochemical techniques. Changes in these values and interactions among them were evaluated. Effects of ACEI intervention were also＇assessed. Results Immunohistochemical staining of the renal tissue showed lowered expressions of tPA and uPA and increased expression of PAI-1 in untreated NX rats vs sham-operated rats. All NX rats showed simultaneous up-regulation of TSP-1 and TGF-β1 in remnant renal tissues as compared with sham-operated ones. Among rats treated with ACEI, the expression of TSP-1 and TGF-β1 appeared to be down-regulated. Positive correlation was identified between TSP-1 expression and tendency of glomeruloscterosis or tubulointerstitial fibrosis. Moreover, the expression of TSP-I was positively correlated with that of TGF-β1 or PAI-1, and negatively correlated with that of uPA or tPA. Conclusion TSP-1 and TGF-β1 were demonstrated to be major promoters for tubulointerstitial fibrosis. Overexpression of TSP-1 may lead to disordered expressions of tPA, uPA and PAI-1 in renal tissues, which can result in imbalance of thrombofibrinolytic system and progression of renal lesions