Expression of CD2AP on podocytes with different pathological types of nephrotic syndrome

目的 观察不同病理类型的原发性肾病综合征(nephrotic syndrome,NS)患者肾小球足细胞中CD2相关蛋白(CD2AP)的表达,探讨其与足细胞损伤的关系.方法 选取原发性NS患者54例,10例同期肾肿瘤切除患者正常肾组织作为对照.肾活检后常规染色观察肾脏组织病理改变,肾组织行免疫荧光法CD2AP和肾小球上皮细胞蛋白-1(GLEPP1)双重标记,对肾小球CD2AP的表达进行定位;分别用real time PCR和免疫组化SP法检测组织中CD2AP的表达,采用real time PCR检测nephrin的表达,透射电镜观察足细胞的结构变化,并定量测量足突密度.结果 (1)NS患者肾小球中CD2AP的表达及nephrin的表达下调,足细胞足突不同程度融合,足突密度降低.(2)病理表现为微小病变性肾病(minimal change disease,MCD)、局灶性节段性肾小球硬化(focal segmental glomerulosclerosis,FSGS)和膜性肾病(membranous nephropathy,MN)的NS患者CD2AP表达及nephrin表达较对照组明显降低,且CD2AP与nephrin表达呈正相关,病理表现为MCD和FSGS的NS患者CD2AP表达与足突密度呈正相关.结论 本研究首次发现原发性NS患者肾小球足细胞中CD2AP的表达降低,且在MCD和FSGS中与足细胞病变程度相关,提示CD2AP低表达在足细胞病变为主的肾小球疾病中发挥重要作用.CD2AP有利于诊断足细胞病变的早期检测,对CD2AP表达减低进行早期干预可能有助于延缓疾病进展.     

成人肾小球微小病变的病理特征

目的探讨成人肾小球微小病变(minimal change disease,MCD)的临床病理学特点。方法回顾性分析符合肾病综合征(nephrotic syndrome,NS)、肾活检病理诊断为MCD、年龄≥18周岁的162例成人患者的病理特征。结果对162例成人MCD肾组织病理改变进行统计发现,肾小球球性硬化、肾间质纤维化、肾间质炎细胞浸润、肾小管萎缩、肾血管病变的比率分别为32.7%、42.6%、55.6%、45.7%、37.0%,除肾间质炎细胞浸润,余病理改变的比率均随着年龄的增长而增加。经年龄纠正后,肾小球球性硬化的比率与患者年龄的关联消失。结论成人MCD病理改变随年龄增长,病变比例及严重程度均增高。     

277例肾病患者足细胞相关分析

目的 分析肾脏疾病患者不同类型的病理改变与足细胞数量的关系,研究二者之间的相关性,寻找足细胞在判断疗效与预后方面的积极意义.方法 对277例肾穿病人肾组织进行常规病理染色及免疫荧光、电镜检查进行病理分型,同时进行肾脏足细胞计数,对二者进行相关性分析,了解肾小球足细胞数量与肾脏病病理分型及预后是否相关.结果 局灶节段性肾小球肾炎(FSGS)、膜性肾病(MN)与搪尿病肾病(DN)和足细胞病变有绝对关系:肾小球足细胞数目与尿蛋白多少呈负相关;尿蛋白是临床判断肾脏病活动与否的依据之一.结论 故肾小球足细胞可以作为判断临床肾病活动的依据之一.     

肾组织中perlecan的表达及其与蛋白尿的关系

目的 观察基膜蛋白多糖（perlecan）在不同病理改变儿童原发性肾病综合征及阿霉素肾病大鼠的肾组织中表达变化，探讨其参与蛋白尿发生的机制。方法 应用免疫组化法检测阿霉素肾病大鼠在阿霉素注射后第7、14、28天时肾组织perlecan的表达变化，并与24h尿蛋白进行相关分析。在69例不同病理类型原发性肾病综合征和血尿患儿的肾组织，应用免疫组化法检测perlecan表达，并分别与尿蛋白肌酐比值及电镜下平均足突宽度（FPW）进行相关分析。结果 在阿霉素肾病大鼠中随着蛋白尿的加重，perlecan在肾小球内染色强度明显减低，且与24h尿蛋白呈显著负相关（P〈0．01）。Perlecan在正常肾组织中沿肾小球血管襻及肾小管基膜分布。肾小球perlecan的表达在MCD、FSGS中分别较正常对照或TBMN显著减低，而在MN中沿增宽的GBM分布，表达显著升高。在IgA肾病中，肾小球内可见perlecan沿血管襻及系膜区分布，蛋白尿组的肾小球中perlecan表达量较单纯血尿组显著减低（P〈0．05）。MCD肾小球中perlecan免疫组化指数与尿蛋白肌酐比值呈负相关，与FPW无显著相关。结论 Perlecan在肾小球内表达减低与阿霉素肾病大鼠及不同病理类型的儿童原发性肾病综合征的蛋白尿的发生有关。     

CD2相关蛋白在肾脏细胞中的分布及其在足细胞中的作用

目的 观察CD2相关蛋白(cD2AP)在肾脏不同细胞系中的表达分布,及其与足细胞裂孔隔膜分子nephrin和细胞骨架蛋白F-actin之间的联系.方法 以DMEM培养基培养人肾小球系膜细胞(HMC)和人肾小管上皮细胞系(HK-2),RPMI 1640培养基培养条件永生化小鼠足细胞系.以RT-PCR及Western blotting方法检测足细胞内CD2AP和nephrin的表达.间接免疫荧光结合激光共焦方法观察CD2AP在HMC、HK-2、未分化及已分化足细胞中的表达情况,及CD2AP与nephtin在足细胞中的共存.直接免疫荧光结合激光共焦方法观察F-actin在足细胞的表达及其与CD2AP的共存.结果 CD2AP均匀分布于HK-2及未分化足细胞的核周及胞浆,而不表达于HMC细胞.在足细胞分化过程中,CD2AP的分布发生了变化,出现向周边聚集的现象.CD2AP与足细胞裂孔隔膜分子nephrin及细胞骨架蛋白F-actin在足细胞中存在共定位关系.结论 CD2AP表达于上皮来源的肾脏固有细胞.CD2AP在足细胞中的分布特点,提示CD2AP可能参与足细胞的分化过程,并与裂孔隔膜分子功能及细胞骨架凋节有关.     

CD2AP在肾脏病学的研究进展

CD2AP是新发现的一种肾小球足细胞裂孔膜蛋白。CD2AP / 小鼠表现为先天性肾病综合症,出生后6~7周将死于肾功能衰竭;CD2AP / 小鼠肾脏病理表现类似于人类FSGS。CD2AP基因突变可能与人类一些肾脏疾病的发病有关。此外,CD2AP还可能通过与其他裂孔膜蛋白相互作用,在足细胞信号转导和功能调节过程中发挥重要作用。     

真武汤对阿霉素所致大鼠肾损伤的治疗作用

 目的：研究真武汤对阿霉素肾病模型（adriamycin nephropathy,AN）大鼠足细胞裂孔隔膜蛋白分子（podocin和nephrin）表达的影响,探讨其防治阿霉素肾病大鼠蛋白尿的机制。方法：采用常规生化、病理方法（包括HE染色、Masson染色及电镜）观察真武汤对AN模型所致纤维化大鼠肾功能、肾组织形态学变化及羟脯氨酸（Hyp）含量的改善作用;采用蛋白免疫印迹等方法探索真武汤对足细胞标志蛋白podocin和nephrin信号分子表达的影响。结果：模型组大鼠尿蛋白（TP）、血尿素氮(BUN)和血清肌酐（SCr）显著增加,肌酐清除率（CCr）显著下降（P<0.05）;Hyp显著增加（P<0.05）;肾组织podocin和nephrin蛋白表达水平显著降低（P<0.05）;肾小管萎缩,基底膜增厚;足突扁平、融合、消失。肾小球集中现象明显;部分肾小管扩张,肾小管上皮细胞变性,蛋白管型明显;肾间质纤维组织增生和较多炎症细胞浸润。与模型组相比,各治疗组TP、BUN和SCr均有一定程度的下降,CCr显著提高;Hyp明显下降（P<0.05）;真武汤组肾组织podocin和nephrin蛋白表达水平显著提高（P<0.05）;肾组织病变程度轻于模型组。结论：真武汤能减少阿霉素肾病大鼠肾组织羟脯氨酸含量,改善肾功能及减轻病理损伤。 真武汤降低模型大鼠蛋白尿的作用可能与其维持足细胞podocin和nephrin的表达有关。     

蟾蜍干预对大鼠肾病模型CD2AP表达的影响

目的 探讨CD2-associated protein（CD2AP）在蟾蜍干预阿霉素肾病模型肾小球中的表达及意义。方法 通过建立阿霉素（ADR）肾病模型，用蟾蜍等干预后，采用免疫组织化学技术观察各组模型大鼠肾小球中CD2AP的表达变化。结果 蟾蜍能使肾小球足细胞CD2AP的表达上调。结论 蟾蜍对肾病大鼠模型病理损伤的修复可能与CD2AP表达上调有关。     

激素抵抗型微小病变病发展为局灶节段性肾小球硬化症6例临床病理分析

目的分析由激素抵抗型微小病变病(steroid-resistant minimal change disease,SR-MCD)发展为局灶节段性肾小球硬化症(focal segmental glomerulosclerosis,FSGS)的临床病理特点,并探讨二者之间的相关性及演变过程中的形态学特点。方法分别利用HE染色、特殊染色、免疫组化染色及电镜检查分析6例患者的临床病理学资料,并复习相关文献。结果 6例患者均表现为肾病综合征,具有激素抵抗的临床特点,初次活检镜下均表现为足细胞弥漫性肿胀,局灶可见增生(≥3个连续排列或叠层),且初次肾活检均可见C4d节段不均匀系膜区较强表达,6例均由SR-MCD发展为FSGS。结论当发现MCD足细胞病变显著或有较强C4d表达时应提示临床医师该患者有向FSGS发展的可能。     

细胞骨架蛋白巢蛋白在人肾足细胞中的表达及意义

目的 检测细胞骨架蛋白巢蛋白在成人正常及病理状态肾组织中的表达,并观察其表达水平与患者尿蛋白的关系,初步探讨巢蛋白与足细胞损伤的关系.方法 正常对照肾组织(外科手术切除)6例,应用免疫组织化学(SP法)和免疫电镜检测巢蛋白的表达;病理状态肾组织:IgA肾病(无蛋白尿,电镜观察无足突融合,IrA-np)4例;IgA肾病(有蛋白尿,IgA-P)17例;膜性肾病8例;局灶性节段性肾小球硬化3例.应用免疫组织化学及即时RT-PCR的方法检测巢蛋白在肾组织中的表达并进行半定量、定量分析,与患者尿蛋白水平进行比较,分析两者之间相关关系.结果 巢蛋白表达在成人正常肾组织的足细胞初级足突中;免疫组织化学半定量及即时RT-PCR结果显示:IgA-np中巢蛋白的表达水平与正常肾组织差异无统计学意义;IgA-P、局灶性节段性肾小球硬化、膜性肾病中,巢蛋白的表达比正常肾组织显著降低(P<0.05),并与24 h尿蛋白呈负相关(r=-0.43,P<0.05).结论 巢蛋白在足细胞中低表达与肾小球中足细胞的损伤有关.     

Co-localization of nephrin,podocin, and the actin cytoskeleton: evidence for a role in podocyte foot process formation

The discovery of the genes for nephrin and podocin, which are mutated in two types of congenital nephrotic syndrome, was pivotal in establishing the podocyte as the central component of the glomerular filtration barrier. In vivo the proteins have been localized to the podocyte slit diaphragm, and there is recent evidence for interaction between the two via the adapter molecule CD2AP. We describe in a human podocyte cell line, the subcellular distribution of nephrin, podocins, and CD2AP and their functional interaction with the cytoskeleton. In addition to membrane expression, nephrin and podocin were detected intracellularly in a filamentous pattern. Double immunolabeling and depolymerization studies showed that nephrin and podocin partially co-localize with actin, most strikingly seen protruding from the tips of actin filaments, and are dependent on intact actin polymers for their intracellular distribution. Treatment of differentiated podocytes with puromycin aminonucleoside, an agent that causes foot process effacement in vivo, disrupted actin and nephrin simultaneously, with loss of cell surface localization. We demonstrate an intimate relationship between nephrin podocin and filamentous actin, and reason that disruption of nephrin/podocin could be a final common pathway leading to foot process effacement in proteinuric diseases.     

Podocyte autophagic activity plays a protective role in renal injury and delays the progression of podocytopathies

The progression of podocytopathies is quite variable among patients and the underlying reason for this remains unclear. Here, we report that autophagic activity in podocytes plays a critical role in controlling the progression of podocytopathies. Morphological and biochemical studies on renal biopsies from patients with minimal change disease (MCD) or focal segmental glomerulosclerosis (FSGS) showed that glomeruli, and in particular podocytes, from MCD patients had higher levels of Beclin1‐mediated autophagic activity than glomeruli from FSGS patients. Repeat renal biopsies of MCD patients enabled tracking of podocyte autophagic activity and confirmed that patients maintaining high podocyte autophagic activity retained MCD status, whereas patients with decreased podocyte autophagic activity progressed to FSGS. Inhibition of autophagic activity, by knocking down Beclin1 or by treating with 3‐methyladenine (3‐MA) or chloroquine, enhanced puromycin aminonucleoside (PAN)‐induced apoptosis of podocytes. In contrast, rapamycin‐mediated promotion of autophagic activity decreased this apoptosis. In PAN‐treated rats, inhibition of autophagy with 3‐MA or chloroquine resulted in earlier onset and greater proteinuria, more extensive foot‐process effacement, and reduction in podocyte markers, whereas rapamycin‐mediated stimulation of autophagy led to decreased proteinuria and less severe foot‐process effacement, but higher expression of podocyte markers. This study demonstrates that podocyte autophagic activity plays a critical protective role in renal injury and that maintaining podocyte autophagic activity represents a potential therapeutic strategy for controlling the progression of podocytopathies. Copyright © 2014 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd     

Immunohistochemical evaluation of podocalyxin expression in glomerulopathies associated with nephrotic syndrome

It is now well established that morphological change of podocytes is closely correlated to the development of proteinuria. The aim of this study was to investigate the role of podocalyxin, a major podocyte protein, in the pathogenesis of glomerulopathies primarily associated with the nephrotic syndrome. Immunohistochemical expression of podocalyxin has been evaluated in 51 renal samples, including healthy controls, patients with podocytopathies (minimal change disease [MCD], focal segmental glomerulosclerosis [FSGS]) and membranous glomerulopathy (MG). A computerized image analysis program has been used. Statistical analysis was performed using analysis of variance and Bonferroni tests. Immunohistochemical expression of podocalyxin has been observed within the podocytes of healthy controls. In MCD, podocalyxin expression was globally reduced despite the normal appearance of the glomeruli. In FSGS, podocalyxin loss was observed in both the segmental sclerotic and the nonsclerotic areas being significantly more prominent in the former. Reduction of podocalyxin in MG was demonstrated for the first time immunohistochemically. The percentage of the stained area was statistical significantly higher in the controls than in each pathologic group. However, among pathologic groups (FSGS, MCD, MG), there was no statistically significant difference. This is one of the few studies investigating podocalyxin immunohistochemical expression in glomerulopathies associated with nephrotic syndrome. The observed reduction in podocalyxin expression suggests that it constitutes a target molecule in nephrotic syndrome pathogenesis regardless of the underlying cause.     

Cyclosporin-A in the treatment of nephrotic syndrome: the importance of monitoring C0 (trough) and C2 (two hours after its administration) blood levels

Cyclosporin-A (CsA) is often used in the treatment of nephrotic syndrome. The effectiveness of CsA and the value of C2 blood levels in the treatment of nephrotic syndrome, due to various glomerular diseases, were studied. Forty-two nephrotic patients (M/F 21/21), with well-preserved renal function (creatinine clearance 87+/-20 ml/min) were included in the study. The original diagnoses were minimal change disease (MCD), focal segmental glomerulosclerosis (FSGS), membranous nephropathy (MN), IgA nephropathy (IgAN), and lupus nephritis (LN). All patients were treated with prednisolone and CsA for 24 months. Cyclosporin-A C0 and C2 blood levels were determined at regular intervals. Remission of the nephrotic syndrome was observed in all patients with MCD, IgAN and LN, in 75% with FSGS and in 83% with MN. Relapses were observed in some patients with MCD (25%) and MN (36%). The C0 levels were 93+/-15 ng/ml and the corresponding C2 levels were 498+/-110 ng/ml. However, significantly lower (340+/-83 ng/ml) or higher (680+/-127 ng/ml) to the average C2 levels were found in 6 patients (14%). No relation of C0 and C2 levels with the remission and relapse rate of the nephrotic syndrome and with renal function impairment was observed. Small doses of CsA with prednisolone are effective in the treatment of nephrotic syndrome. Although an individual variation of C2 was observed for the same target C0 levels, no relation of C2 levels was found with the remission or relapse rate of the nephrotic syndrome.     

Direct effect of plasma permeability factors from patients with idiopatic FSGS on nephrin and podocin expression in human podocytes

The presence of circulating plasma factors (PF) altering renal permeability to proteins has been previously described in patients with focal segmental glomerulosclerosis (FSGS). Since these patients show reduced nephrin and podocin expression at renal biopsy, we evaluated the effect of serum and PF from patients with FSGS on nephrin and podocin expression in human podocytes. We studied 7 sera from patients with steroid-resistant FSGS, 3 from patients with nephrotic syndrome caused by non-immune disease, and 6 from healthy subjects. PF was prepared from plasmapheresis eluates of 2 patients with post-transplant recurrence of FSGS. Purification procedure was based on protein A Sepharose chromatography and differential precipitation in ammonium sulphate. Nephrin and podocin expression was semi-quantitatively evaluated by immunofluorescence. We found that serum and PF from FSGS patients rapidly induced redistribution and loss of nephrin in podocytes. This effect was associated with cytoskeleton redistribution and inhibited by cytochalasin B and sodium azide. On the contrary, podocin expression was unchanged after incubation with serum and PF from FSGS patients for short periods, but markedly reduced at 24 h. Our results demonstrate that serum and PF from FSGS patients may directly affect nephrin and podocin in human podocytes, thus providing new insights into the mechanisms causing proteinuria in FSGS.     

A new role for the neuronal ubiquitin C-terminal hydrolase-L1 (UCH-L1) in podocyte process formation and podocyte injury in human glomerulopathies

Glomerular epithelial cell (podocyte) injury is characterized by foot process retraction, slit diaphragm reorganization, and degradation of podocyte-specific proteins. However, the mechanisms underlying podocyte injury are largely unknown. The ubiquitin C-terminal hydrolase-L1 (UCH-L1) is a key modulator of ubiquitin modification in neurons. Like neurons, UCH-L1 expression was associated with an undifferentiated status in cultured human podocytes, whereas differentiation and arborization decreased UCH-L1 and monoUb expression. Inhibition of UCH-L1 induced time and concentration-dependent process formation with alpha-actinin-4 distribution to the cell membrane and processes. An immunohistochemical approach was used to evaluate whether UCH-L1 expression was associated with podocyte injury in 15 different human glomerular diseases. Whereas normal kidneys expressed no UCH-L1 and little ubiquitin, a subset of human glomerulopathies associated with podocyte foot process effacement (membranous nephropathy, SLE class V, FSGS) de novo expressed UCH-L1 in podocyte cell bodies, nuclei, and processes. Interestingly, UCH-L1 expression correlated with podocyte ubiquitin content and internalization of the podocyte-specific proteins nephrin and alpha-actinin-4. In contrast, minimal change glomerulonephritis, a reversible disease, demonstrated minimal UCH-L1 and ubiquitin expression with intact alpha-actinin-4 but internalized nephrin. Glomerular kidney diseases typically not associated with foot process effacement (SLE class IV, ANCA+ necrotizing GN, amyloidosis, IgA nephritis) expressed intermediate to no UCH-L1 and ubiquitin. These studies show a role for UCH-L1 and ubiquitin modification in podocyte differentiation and injury.     

Clinicopathological Characteristics of Obesity-associated Focal Segmental Glomerulosclerosis

Obesity-related glomerulopathy (ORG) is a secondary form of focal segmental glomerulosclerosis (FSGS) occurring in obese patients with a body-mass index higher than 30?kg/m². It is typically manifested by nephrotic-range proteinuria without full nephrotic syndrome, and progressive renal insufficiency. Characteristic morphologic features include the consistent presence of glomerulomegaly, predominance of perihilar variant of FSGS, and the relatively mild fusion of visceral epithelial cell foot processes. The concept of podocyte depletion as a driver of the glomerular scarring in obesity-associated FSGS is well documented. The underlying mechanisms are likely to be related in part to the oxidative stress and the impairment of the integrity of the slit diaphragm and cell adhesion resulting mainly from angiotensin II and transforming growth factor-β. These proapoptotic cytokines are upregulated in obesity in response to insulin resistance, compensatory hyperinsulinemia and glomerular hyperfiltration-hypertension mediated mechanical stress. This review is designed to discuss the clinicopathologic features of obesity-associated FSGS, with a focus on the podocyte injury, which is involved in the onset and progression of the glomerulosclerotic process. Ultrastructural glomerular lesions are documented.