胰岛移植改善糖尿病肾病大鼠的足细胞损害

Islet transplantation alleviates podocyte injury in diabetic nephropathy rats

目的 探讨胰岛移植改善糖尿病肾病（DN）大鼠足细胞损害的作用及其机制.方法 采用腹腔注射单剂链脲菌素建立SD大鼠DN模型（简称：建模）.实验分正常对照组、DN组和胰岛移植组.胰岛移植组在建模后8周行右侧肾背膜下胰岛移植.于建模第12周（移植后4周）,测定各组大鼠尿微量白蛋白与尿肌酐比值,监测各组大鼠血糖水平;收集各组大鼠肾脏行病理组织检查和免疫荧光检查及肾脏电镜检测;采用免疫组织化学法观察各组肾小球中突触极蛋白（synaptopodin）和转化生长因子β1（TGF-β1）蛋白的表达.结果 建模后8周（移植前）,DN组和胰岛移植组大鼠血糖水平分别为（24.62±3.31） mmol/L和（25.23±2.61） mmol/L,均较正常对照组显著升高（P＜0.05）;胰岛移植组大鼠在移植后平均3.3d,血糖下降至正常,并均可维持正常;而此时DN组大鼠的血糖水平未出现明显变化,两组差异有统计学意义（P＜0.05）.建模第8周（移植前）,DN组和胰岛移植组24 h尿蛋白水平分别为（46.82±5.87）mg和（51.26±4.69）mg,均显著高于正常组的（8.07±1.17）mg（P＜0.05）.建模第12周（移植后4周）,胰岛移植组尿微量白蛋白与尿肌酐比值水平为（0.33±0.04） mg/mmol,显著低于DN组的（2.36±0.73）mg/mmol,差异有统计学意义（P＜0.001）.HE染色和免疫荧光染色显示,胰岛团周围有新生血管,胰岛素分泌旺盛.电镜下可见,DN组足细胞局部足突融合,基底膜节段增厚;胰岛移植组足突排列整齐,基底膜结构清晰,无增厚.DN组和胰岛移植组肾小球内synaptopodin蛋白表达较正常对照组明显减弱（P＜0.05）;胰岛移植组synaptopodin 蛋白表达较DN组显著增强（P＜0.05）.DN组和胰岛移植组TGF-β1蛋白表达较正常对照组显著升高（P＜0.05）;DN组TGF-β1蛋白表达较胰岛移植组显著升高（P＜0.05）.结论 胰岛移植可以通过抑制TGF-β1通路,改善DN大鼠足细胞损伤,减少甚至逆转蛋白尿的产生.

Objective To investigate the mechanism of islet transplantation lessening renal damage of diabetic nephropathy （DN） rat model.Method Rat DN model was established by intraperitoneal injection of a single-dose streptozotocir.The rats were divided into normal control group, DN group and islet transplant group.Islet transplantation was taken on the right renal capsule in transplantation group at 8th week after the modeling.At week 12 after the modeling, the urinary protein, urinary creatinine and blood glucose in each group were determined.The kidneys were collected, and transplant islet HE staining, immunofluorescence, kidney electron microscopy were done.Synaptopodin and transforming growth factor-β1 （TGFβ1） protein expression was observed in renal tissues of each group by immunohistochemical staining.Result The urine protein and urinary creatinine ratio in islet transplant group was significantly lower than in DN group （P〈0.001）.Blood glucose level in islet transplant group had no significant difference （P〉0.05） with the control group, but was significantly lower than in DN group （P 〈 0.05）.Islet cells by HE staining and immunofluorescence staining showed new blood vessels around the islets, and the insulin secretion was exuberant.Under an electron microscope, there was local fusion of podocyte foot processes, and segmental thickening of the basement membrane in DN group;in islet transplant group, the foot processes of podocytes were neat, basement membrane structure was clear and had no thickening.Synaptopodin protein expression was significantly decreased in the glomeruli of DN group and islet transplant group as compared with the control group （P〈0.05）, and that in islet transplant group was significantly enhanced （P〈0.05） as compared with DN group.The expression of TGFβ1 in DN group and islet transplant group was significantly increased （P〈0.05） as compared with control group, and that in DN group was significantly higher （P〈0.05） than in islet transplant group.Conclusion Islet transplantation can inhibit TGFβ1 pathway, improve DN podocyte injury in rats, and alleviate or even reverse proteinuria.