膜性肾病肾活检组织中nephrin和podocin表达改变及其意义

Expression changes of nephrin and podocin in patients with membranous nephropathy

目的:检测膜性肾病(MN)患者肾活检组织中nephrin、podocin的表达和分布,分析MN蛋白尿与nephrin和podocin表达改变的关系,探讨肾小球足细胞裂孔隔膜蛋白nephrin和podocin在MN蛋白尿发生中的作用。方法:选取2005年1月至2008年1月经肾穿刺活检病理确诊为II、III期MN的患者22例,其中肾病综合征组15例(MN-A组),非肾病综合征组7例(MN-B组),临床上排除系统性红斑狼疮、乙肝相关性肾病、糖尿病肾病以及肿瘤等继发性肾脏疾病;另取5例因肾脏肿瘤行一侧肾切除的远端相对正常肾脏组织作为对照(对照组)。收集并分析患者的主要临床表现、内生肌酐清除率(Ccr)、尿常规、24h尿蛋白定量、血清白蛋白(Alb)、血脂等相关临床资料;按常规方法取肾组织制备3μm厚石蜡切片,行HE、PAS、PASM、Masson染色普通光镜以及免疫组化(IgG、IgA、IgM、C3、C4、C1q)检查;各组肾组织行nephrin、podocin及IV型胶原α3链免疫荧光双套色染色,激光共聚焦显微镜下观察nephrin、podocin在两组MN及对照组肾组织中表达及分布的改变,以计算机图像分析系统进行半定量分析。结果:22例MN病理分期分别为II期14例,III期8例;肾小球内免疫球蛋白及补体的沉积以IgG和C3为主,呈颗粒状沿毛细血管袢弥漫性分布。对照组肾组织免疫荧光染色可见nephrin和podocin沿肾小球毛细血管袢呈均匀连续线样分布;MN患者肾小球内nephrin与podocin表达皆明显减弱,免疫荧光强度降低,分布不均,部分区域有节段性缺失,部分由线状分布变成颗粒状分布,与对照组相比差异有统计学意义(P<0.05);MN-A组与MN-B组比较,MN-A组肾小球nephrin和podocin的平均表达量均低于MN-B组,差异有统计学意义(P<0.05),且尿蛋白量与nephrin或podocin表达呈负相关。结论:MN患者肾小球内nephrin和podocin表达量均降低,分布形式亦发生改变,部分呈节段性缺失或不连续颗粒状分布,并与尿蛋白排泄量呈负相关,提示nephrin和podocin表达的减少及分布异常可能与蛋白尿发生及蛋白尿程度有关;但其损伤的始动因素仍需进一步探讨。

Objective：To detect the expression changes of nephrin and podocin in patients with membranous nephropathy（MN）,and further to disclose the possible effects of nephrin and podocin in the development of proteinuria in MN. Methodology：Twenty-two patients diagnosed as MN by the renal biopsy,included 15 cases with nephrotic syndrome proteinuria（MN-A） and 7 cases with non-nephrotic syndrome proteinuria（MN-B）,were enrolled in this study.5 normal renal samples were regarded as the control group.The clinical parameters including urine routine test,endogenous creatinine clearance rate,serum albumin and quantity of urine protein excretion were collected.The expression of the nephrin and podocin in the glomerular podocyte were examined by immunofluorescence and semi-quantitated by image-analysis system. Results：（1） According to pathological changesof MN,14 cases are in grade II and 8 cases are in grade III.Most of our patients presented IgG and C3 deposition in the glomeruli by immunohistochemistry examination.（2） In control group,the distribution of nephrin and podocin showed a linear pattern along the glomerular basement membrane.While the staining of nephrin and podocin on glomeruli was uneven,and lost of linear pattern with granular pattern in MN group.（3） In MN-A group and MN-B group,the glomerular expression of nephrin and podocin decreased significantly compared with those of control group（P〈0.05）.In MN-A group,the glomerular expression of nephrin and podocin decreased significantly compared with those of MN-B group（P〈0.05）. Conclusion：The dramatic decrease of nephrin and podocin expression might contribute to the development of proteinuria in the patients of MN,which suggesting that nephrin and podocin may be the injury target in MN and implying the roles of nephrin and podocin in the pathogenesis of proteinuric diseases.