Cell coat of podocytes in patients with nephrotic syndrome

Renal biopsies from 23 patients with the nephrotic syndrome and five patients with slight or no proteinuria were examined for the presence of cell coat of podocytes by light and electron microscopy. Of those with nephrotic syndrome, five had minimal change disease, nine focal glomerular sclerosis, six membraneous nephropathy and three amyloidosis. Colloidal iron and phosphotungstic acid stains were used for the demonstration of anionic and neutral polysaccharide components of the cell coat. On light microscopy, the colloidal iron reaction showed a reduction in intensity of the stain in glomeruli of patients with massive proteinuria, as compared to those with slight or no proteinuria. On electron microscopy, only the cell coat lining the surface of the foot processes disappeared parallel to the loss of these structures, while the coat covering the surface facing the urinary space remained unchanged with both stains.     

原发性肾病综合征(PNS)患儿血清NEFA/ALB比值的变化

目的:观察初发及缓解原发性肾病综合征(PNS)患儿血清NEFA/ ALB 比值的变化,为临床PNS 的诊断及病情评估提供新指标。方法:对52 例PNS 急性期患儿、34 例PNS 缓解期患儿和50 例健康儿童的血清白蛋白(ALB)、游离脂肪酸(NEFA)、尿素氮(BUN)、尿酸(UA)、肌酐(Scr)、总胆固醇(TC)、甘油三酯(TG)、低密度脂蛋白胆固醇(LDL-C)、高密度脂蛋白胆固醇(HDL-C)水平进行定量分析,并对NEFA/ ALB 比值与其他生化指标进行相关性分析。结果:与正常对照组相比,急性组和缓解组患儿血清ALB、HDL-C 水平均显著降低(P< 0.05),而急性组患儿血清NEFA/ ALB、TC、TG、LDL-C、UA 显著升高(P< 0.05);缓解组患儿仅TG、LDL-C 显著升高(P< 0.05)。与缓解组相比,急性组患儿血清ALB 水平显著降低(P <0.05),而血清NEFA/ ALB、TC、TG、LDL-C、UA、BUN、Scr 水平均显著升高(P< 0.05)。将血清生化指标比较中差异有统计学意义的指标与NEFA/ ALB 比值进行相关分析,结果显示NEFA/ ALB 比值与TC、TG、LDL-C、UA、BUN 呈显著正相关性(P 均<0.05),与ALB 呈显著负相关性(P< 0.05)。多元线性逐步回归分析结果显示,血清NEFA/ ALB 比值与BUN 独立相关(β=0.045,t =1.602,P =0.003)。结论:在PNS 疾病发生和发展过程中,NEFA/ ALB 比值升高预示患儿的肾脏功能损伤加重或肾功能降低,对其进行监测有助于临床病情评估与判断。     

Nephrin redistribution on podocytes is a potential mechanism for proteinuria in patients with primary acquired nephrotic syndrome

We investigated the distribution of nephrin by immunofluorescence microscopy in renal biopsies of patients with nephrotic syndrome: 13 with membranous glomerulonephritis (GN), 10 with minimal change GN, and seven with focal segmental glomerulosclerosis. As control, six patients with IgA GN without nephrotic syndrome and 10 normal controls were studied. We found an extensive loss of staining for nephrin and a shift from a podocyte-staining pattern to a granular pattern in patients with nephrotic syndrome, irrespective of the primary disease. In membranous GN, nephrin was co-localized with IgG immune deposits. In the attempt to explain these results, we investigated in vitro whether stimuli acting on the cell cytoskeleton, known to be involved in the pathogenesis of GN, may induce redistribution of nephrin on the surface of human cultured podocytes. Aggregated but not disaggregated human IgG(4), plasmalemmal insertion of membrane attack complex of complement, tumor necrosis factor-alpha, and puromycin, induced the shedding of nephrin with a loss of surface expression. This phenomenon was abrogated by cytochalasin and sodium azide. These results suggest that the activation of cell cytoskeleton may modify surface expression of nephrin allowing a dislocation from plasma membrane to an extracellular site.     

原发性肾病综合征患儿539例病理类型及随访

目的分析原发性肾病综合征（PNS）患儿的病理类型、治疗及随访情况。方法纳入2005年1月至2009年12月在湖南省儿童医院肾内科住院的诊断为PNS,进行肾脏病理学检查且随访时间≥6个月的患儿,根据年龄分为〈2岁组、～5岁组、～10岁组和〉10岁组,对不同年龄组肾脏病理类型、对糖皮质激素的反应、转归及随访资料进行分析。结果共纳入539例PNS患儿,男性402例,女性137例,男女比例为2.9∶1;〈2岁组159例（29.5%）,～5岁组269例（49.9%）,～10岁组84例（15.6%）,〉10岁组27例（5.0%）（P〈0.01）。①微小病变274例（50.8%）,局灶节段性肾小球硬化79例（14.6%）,系膜增生性肾小球肾炎173例（32.1%）,膜增生性肾小球肾炎6例（1.1%）,膜性肾病4例（0.74%）,增生硬化性肾小球肾炎2例（0.37%）,脂蛋白肾病1例（0.18%）。不同年龄组间肾脏病理类型的分布差异有统计学意义（P〈0.05）。②对糖皮质激素敏感和依赖的PNS患儿以微小病变为主（分别为62.4%和69.6%）,对糖皮质激素耐药的PNS患儿以系膜增生性肾小球肾炎为主（48.4%）。③539例中239例完全缓解,75例部分缓解,61例无效,158例症状控制,尿蛋白（-）,但仍在服用泼尼松。6例患儿分别因对糖皮质激素耐药,病情不能缓解,合并严重感染或进展至终末期肾病放弃治疗而死亡。结论儿童PNS的发病高峰年龄、肾脏病理类型以及对糖皮质激素耐药的发生率可能已发生改变,并且在不同年龄患儿间存在差异。     

Immunoconglutinin and complement changes in steroid sensitive relapsing nephrotic syndrome of children

Elevation of serum immunoconglutinin was detected in patients in relapse with steroid sensitive nephrotic syndrome. The significance of this evidence of immunological disturbance is discussed in relation to the aetiology of the disease.     

mTORC1 activation triggers the unfolded protein response in podocytes and leads to nephrotic syndrome

Although podocyte damage is known to be responsible for the development of minimal-change disease (MCD), the underlying mechanism remains to be elucidated. Previously, using a rat MCD model, we showed that endoplasmic reticulum (ER) stress in the podocytes was associated with the heavy proteinuric state and another group reported that a mammalian target of rapamycin complex 1 (mTORC1) inhibitor protected against proteinuria. In this study, which utilized a rat MCD model, a combination of immunohistochemistry, dual immunofluorescence and confocal microscopy, western blot analysis, and quantitative real-time RT-PCR revealed co-activation of the unfolded protein response (UPR), which was induced by ER stress, and mTORC1 in glomerular podocytes before the onset of proteinuria and downregulation of nephrin at the post-translational level at the onset of proteinuria. Podocyte culture experiments revealed that mTORC1 activation preceded the UPR that was associated with a marked decrease in the energy charge. The mTORC1 inhibitor everolimus completely inhibited proteinuria through a reduction in both mTORC1 and UPR activity and preserved nephrin expression in the glomerular podocytes. In conclusion, mTORC1 activation may perturb the regulatory system of energy metabolism primarily by promoting energy consumption and inducing the UPR, which underlie proteinuria in MCD.     

IgG subclasses in children with nephrotic syndrome

To determine whether the hypogammaglobulinemia of childhood nephrotic syndrome is characterized by symmetric depression of the IgG subclasses, the authors compared the IgG subclass concentrations in nephrotic patients in relapse versus remission. The authors used a highly sensitive monoclonal antibody-based enzyme immunoassay that allows quantitation with comparable precision of all four subclasses. They analyzed 28 sera obtained from 22 nephrotic patients during relapse (n = 16) and/or remission (n = 12). The mean ages of the two groups were similar. IgG1 and IgG2 were significantly decreased during relapse compared with remission, whereas IgG3 and IgG4 were not significantly different. This pattern of asymmetric depression of IgG subclasses supports a cause other than urinary losses in the pathogenesis of this abnormality.     

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.     

CD2相关蛋白在肾病综合征中的表达及意义

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。     

Foothold of NPHS2 mutations in primary nephrotic syndrome

Glomerular podocytes are highly specialized cells with a complex cytoarchitecture. Their most prominent features are interdigitated foot processes with filtration slits in between. These are bridged by the slit diaphragm, which plays a major role in establishing the selective permeability of the glomerular filtration barrier. We searched Medline and Pubmed using the combination of keywords "NPHS2", "podocin", "steroid-resistant nephrotic syndrome," and "genetics" to identify studies describing an association between NPHS2 gene and renal disease. The highly dynamic foot processes contain an actin-based contractile apparatus comparable to that of smooth muscle cells. Mutations affecting several podocyte proteins lead to rearrangement of the cytoskeleton, disruption of the filtration barrier, and subsequent renal disease. The fact that the dynamic regulation of the podocyte cytoskeleton is vital to kidney function has led to podocytes emerging as an excellent model system for studying actin cytoskeleton dynamics in a physiological context. Injury to podocytes leads to proteinuria, a hallmark of most glomerular diseases. Recent studies have led to a considerable increase in our understanding of podocyte biology including composition and arrangement of the cytoskeleton involved in the control of ultrafiltration. Moreover, disturbances of podocyte architecture resulting in the retraction of foot processes and proteinuria appear to be a common theme in the progression of an acquired glomerular disease. In hereditary nephrotic syndromes identified over the last few years, all mutated gene products were localized in podocytes. This review integrates our recent physiological and molecular understanding of the role of podocytes during the maintenance and failure of the glomerular filtration barrier.     

Vascular endothelial growth factor (VEGF-C1)-dependent inflammatory response of podocytes in nephrotic syndrome glomerulopathies in children: an immunohistochemical approach

AIMS: To analyse expression and distribution of vascular endothelial growth factor (VEGF-C1), podocalyxin and synaptopodin within renal tissue in nephrotic syndrome glomerulopathies in children. METHODS AND RESULTS: Renal biopsies performed at the time and in the manner recommended by the World Health Organization. The study group consisted of submicroscopic glomerulonephritis (n = 10), diffuse mesangial proliferation (n = 14) and focal segmental glomerulosclerosis (n = 5). The control tissue consisted of macroscopically normal appearing cortex taken from kidneys resected for localized neoplasms (n = 3). Material for immunohistochemistry was fixed in Bouin's solution and embedded in paraffin. Indirect immunohistochemistry using monoclonal anti-human antibodies directed against VEGF-C1, podocalyxin and synaptopodin was employed. The distribution of markers was quantified by computerized image analysis. In non-sclerosed glomeruli (within podocyte cytoplasm), VEGF-C1 was more expressed in podocytes of all groups (P < 0.0002), while the distribution of synaptopodin was less expressed in all groups (P < 0.0002). There was no statistical difference between all groups in the expression of podocalyxin. CONCLUSIONS: The increased permeability of the filtration barrier in steroid-resistant glomerulopathies may be a consequence of subcellular changes in podocytes resulting from decreased expression of synaptopodin. Moreover, impaired permeability of endothelium could be secondary to increased expression of podocyte-derived VEGF-C1.     

Impaired primary antibody response in experimental nephrotic syndrome.

The primary antibody response to sheep red blood cells (SRBC) is reduced in rats with aminonucleoside of puromycin (AP) nephrosis, as measured by haemagglutination and IgM antibody forming spleen cells (AFC). Since rats immunized 1 day after AP administration had a normal antibody response, these studies suggest that the impaired immune response in nephrotic rats is not due to a direct effect of AP but that it is secondary to the nephrotic state.