大鼠足细胞损害后肾小球血管生成素的异常表达及其意义

Abnormal expression of angiopoietins in glomerulus following podocyte injury and its role in the development of progressive glomerulosclerosis in rats

目的:探讨大鼠足细胞损害后,内源性血管生成素的异常变化及其在进行性肾小球硬化中的病理作用。方法:选择柔红霉素诱导足细胞损害的大鼠模型作为研究对象,80只健康雄性Wistar大鼠,随机分为假手术(sham)组25只、单侧肾切除(UNx)组25只和UNx+柔红霉素(DRB)组30只。DRB组大鼠,摘除左肾后的第7、14d,从尾静脉注射柔红霉素5mg.kg-1各1次。然后,分别于造模后的第1、2、4、6、8周,随机取各组大鼠5只,收集24h尿量,采血取肾,检测24h尿蛋白定量(24hUPQ)、血肌酐(Scr)和尿素氮(BUN),用PAS染色、免疫组化、原位杂交和透射电镜技术进行病理形态学分析。结果:DRB组的24hUPQ、BUN、Scr显著高于相同时点的sham组和UNx组;肾小球硬化指数(GSI)随病变的进展逐步升高。免疫组化和原位杂交显示,DRB组的肾小球表达Ang1mRNA和Ang1蛋白下调,表达Ang2mRNA和Ang2蛋白上调。电镜显示,DRB组逐步出现严重的足细胞损害。Sham组和UNx组的肾小球没有病理改变。DRB组的Ang1mRNA表达与Ang2mRNA表达呈负相关;Ang1蛋白表达与Ang1mRNA表达呈正相关,与Ang2蛋白表达、四型胶原(CoIV)蛋白表达、GSI、24hUPQ、Bun、Scr呈负相关;Ang2蛋白表达与Ang2mRNA表达、CoIV蛋白表达、GSI、24hUPQ、BUN、Scr之间呈正相关。结论:足细胞损伤可能是导致肾小球内Ang1和Ang2表达失衡的主要原因,Ang1表达下调,失去对Ang2的抑制,使Ang2表达上调,并介导肾小球滤过膜通透性增高和肾小球硬化的形成。

AIM： To study the potential pathological role of abnormal expression of endogenous angiopoietins in progressive glomerulosclerosis. METHODS： 80 male Wistar rats were randomly allocated into sham operation group （sham, n=25）, unilateral nephrectomy group （UNx, n=25） and UNx ＋ daunorubicin （DRB）group （n=30）. The rats in DRB group were intravenously injected with DRB （5 mg/kg） on the seventh and the fourteenth day respectively after excising one kidney. Then, at week 1,2, 4, 6 and 8, 5, male Wistar rats from each group were taken randomly for determining 24 h urinary protein quantitative measurement （24hUPQ）, BUN, Scr, and the kidneys were examined by electronic staining and in situ hybridization histochemistry. RESULTS： There was a trend towards an increase respectively in levels of 24hUPQ, Bun, Scr, GSI in DRB from week 2 to week 8. Electronic micruscope revealed that podocyte injury presented in DRB group. Expression of Angl mRNA and protein in glomerulus in DRB group decreased, while expression of Ang2 protein in glomeruli in DRB group increased. In DRB group, expression of Angl protein had a negative correlation with 24hUPQ, BUN, Scr, GSI, expression of Ang2 protein and CoIV protein. Expression of Ang2 protein had a positive correlation with 24hUPQ, BUN, Scr, GSI, expression of ColV protein. CONCLUSION ： Podocyte injury may lead to glomeruli abnormally express angiopoietius. A decrease in expression of Angl, and upregulation in expression of Ang2 may facilitate progressive glomerulosclerosis in the rat.