nephrin and Glomerulonephritis--Membranous

Topics: Animals; Antigen-Antibody Complex; Complement Activation; Complement Membrane Attack Complex; Glomerulonephritis; Glomerulonephritis, Membranous; Humans; Immunoglobulin G; Intracellular Signaling Peptides and Proteins; Low Density Lipoprotein Receptor-Related Protein-2; Membrane Proteins; Neprilysin; Proteinuria

Idiopathic membranous nephropathy (IMN) has a varied clinical course that requires accurate prediction as a prerequisite for treatment administration. Currently, its prognosis relies on proteinuria, a clinical parameter whose onset lags behind kidney injury. Increased urinary excretion of matrix metalloproteinase-9 (MMP-9) and nephrin has been reported in a number of IMN-like glomerular diseases in which they reflected disease severity. However, little or nothing is known of the importance of these biomarkers in IMN, a major cause of adult nephrotic syndrome. To highlight their potential, we measured both biomarkers and assessed their relationships with key parameters of renal function in IMN.. We quantified urinary MMP-9 and nephrin in 107 biopsy-proven IMN patients and 70 healthy subjects by enzyme-linked immunosorbent assay (ELISA). We then compared biomarker levels between patients and healthy subjects and among patients with different clinical features. We also determined the relationship of each biomarker with proteinuria and the estimated glomerular filtration rate (eGFR).. Urinary MMP-9 and nephrin were significantly higher in IMN compared to healthy controls. Unlike nephrin, MMP-9 correlated significantly with proteinuria and was significantly higher among patients with nephrotic range proteinuria. Both biomarkers were correlated with eGFR, but only MMP-9 was significantly higher in patients with eGFR less than 90 ml/min/1.73 m. Our findings suggest that urinary MMP-9 holds a greater potential than urinary nephrin in monitoring the severity of IMN.

Topics: Biomarkers; Case-Control Studies; Cross-Sectional Studies; Female; Follow-Up Studies; Glomerulonephritis, Membranous; Humans; Male; Matrix Metalloproteinase 9; Membrane Proteins; Middle Aged; Prognosis

Lupus nephritis (LN) is a common and devastating complication caused by systemic lupus erythematosus. In this study, we evaluated the expression and mechanism of Fos-related antigen 2 (Fra-2) in LN. The results showed that Fra-2 was significantly increased in kidney biopsies of LN patients compared with healthy controls and other kidney disease in glomerular podocytes. The MRL/lpr mouse strain is a murine model of lupus, and it was used to study the mechanisms of Fra-2 in LN. The results showed that Fra-2 was expressed in the glomerular podocytes. We investigated the effects of inflammatory stimuli on Fra-2 protein expression in the glomerular podocytes, and found that interferon gamma was most effective at increasing Fra-2 protein expression. Knockdown of Fra-2 using siRNA enhanced the protein expression of nephrin. Therefore, Fra-2 may be a specific drug target for podocyte injury in LN.

Topics: Animals; Antiviral Agents; Fos-Related Antigen-2; Gene Knockdown Techniques; Glomerulonephritis, IGA; Glomerulonephritis, Membranous; Glomerulosclerosis, Focal Segmental; Humans; IgA Vasculitis; Interferon-gamma; Lupus Nephritis; Membrane Proteins; Mice; Mice, Inbred MRL lpr; Nephrosis, Lipoid; Podocytes

CD40/CD40 ligand (CD40L) dyad, a co-stimulatory bi-molecular complex involved in the adaptive immune response, has also potent pro-inflammatory actions in haematopoietic and non-haematopoietic cells. We describe here a novel role for soluble CD40L (sCD40L) as modifier of glomerular permselectivity directly acting on glomerular epithelial cells (GECs). We found that stimulation of CD40, constitutively expressed on GEC cell membrane, by the sCD40L rapidly induced redistribution and loss of nephrin in GECs, and increased albumin permeability in isolated rat glomeruli. Pre-treatment with inhibitors of CD40-CD40L interaction completely prevented these effects. Furthermore, in vivo injection of sCD40L induced a significant reduction of nephrin and podocin expression in mouse glomeruli, although no significant increase of urine protein/creatinine ratio was observed after in vivo injection. The same effects were induced by plasma factors partially purified from post-transplant plasma exchange eluates of patients with focal segmental glomerulosclerosis (FSGS), and were blocked by CD40-CD40L inhibitors. Moreover, 17 and 34 kDa sCD40L isoforms were detected in the same plasmapheresis eluates by Western blotting. Finally, the levels of sCD40Lwere significantly increased in serum of children both with steroid-sensitive and steroid-resistant nephrotic syndrome (NS), and in adult patients with biopsy-proven FSGS, compared to healthy subjects, but neither in children with congenital NS nor in patients with membranous nephropathy. Our results demonstrate that sCD40L directly modifies nephrin and podocin distribution in GECs. Moreover, they suggest that sCD40L contained in plasmapheresis eluates from FSGS patients with post-transplant recurrence may contribute, presumably cooperating with other mediators, to FSGS pathogenesis by modulating glomerular permeability.

Topics: Adolescent; Adrenal Cortex Hormones; Adult; Albumins; Animals; CD40 Antigens; CD40 Ligand; Cell Membrane; Cell Membrane Permeability; Child; Child, Preschool; Cytotoxins; Epithelial Cells; Female; Gene Expression Regulation; Glomerulonephritis, Membranous; Glomerulosclerosis, Focal Segmental; Hemodialysis Solutions; Humans; Intracellular Signaling Peptides and Proteins; Kidney Glomerulus; Kidney Transplantation; Male; Membrane Proteins; Mice; Nephrotic Syndrome; Plasma Exchange; Plasmapheresis; Rats

Proteinuria is a major feature of lupus nephritis (LN) and reflects podocyte injury. Analysis of podocyte biomarkers was performed attempting to identify if podocyte phenotype is distinct in pure membranous and proliferative LN. Expression of synaptopodin, Wilms tumor protein 1 (WT1), glomerular epithelial protein 1 (GLEPP1) and nephrin was evaluated in 52 LN biopsies by immunohistochemistry. Preserved synaptopodin expression was observed in only 10 (19.2%) of all biopsies while 42 (80.8%) had reduced expression. Both groups had comparable proteinuria at the time of biopsy (p = 0.22); however, in the mean follow-up of four years there was a tendency toward lower mean levels of proteinuria in patients with preserved synaptopodin staining (0.26±0.23 vs. 0.84±0.90 g/24 h, p = 0.05) compared with those with diminished expression. Thirty-nine (75%) biopsies were classified as proliferative and 13 (25%) as pure membranous. Comparison of podocyte biomarkers demonstrated a predominance of preserved staining of synaptopodin (69.2%), WT1 (69.2%), GLEPP1 (53.9%) and nephrin (60%) in the pure membranous group whereas only <10% of the proliferative showed preserved expression. Our data suggest that in proliferative forms there seems to occur structural podocyte damage, whereas in the pure membranous the predominant preserved pattern suggests a dysfunctional podocyte lesion that may account for the better long-term prognosis of proteinuria outcome.

Topics: Adult; Biomarkers; Biopsy; Cell Proliferation; Female; Glomerulonephritis, Membranoproliferative; Glomerulonephritis, Membranous; Humans; Immunohistochemistry; Lupus Nephritis; Male; Membrane Proteins; Microfilament Proteins; Middle Aged; Podocytes; Prognosis; Proteinuria; Receptor-Like Protein Tyrosine Phosphatases, Class 3; Time Factors; WT1 Proteins; Young Adult

Recent studies have shown a beneficial effect of rapamycin in passive and active Heymann Nephritis (HN). However, the mechanisms underlying this beneficial effect have not been elucidated.. Passive Heymann Nephritis (PHN) was induced by a single intravenous infusion of anti-Fx1 in 12 Sprague-Dawley male rats. One week later, six of these rats were commenced on daily treatment with subcutaneous rapamycin 0.5 mgr/kg (PHN-Rapa). The remaining six rats were used as the proteinuric control group (PHN) while six more rats without PHN were given the rapamycin solvent and served as the healthy control group (HC). All rats were sacrificed at the end of the 7th week.. Rapamycin significantly reduced proteinuria during the autologous phase of PHN. Histological lesions were markedly improved by rapamycin. Immunofluorescence revealed attenuated deposits of autologous alloantibodies in treated rats. Untreated rats showed decreased glomerular content of both nephrin and podocin whereas rapamycin restored their expression.. Rapamycin monotherapy significantly improves proteinuria and histological lesions in experimental membranous nephropathy. This beneficial effect may be mediated by inhibition of the alloimmune response during the autologous phase of PHN and by restoration of the normal expression of the podocyte proteins nephrin and podocin.

Topics: Animals; Disease Models, Animal; Gene Expression Regulation; Glomerulonephritis, Membranous; Intracellular Signaling Peptides and Proteins; Kidney Glomerulus; Male; Membrane Proteins; Proteinuria; Rats; Sirolimus

To observe the expression of nephrin in hepatitis B virus-associated membranous nephropathy (HBV-MN), and investigate the impairment and significance of podocyte in HBV-MN.. The protein expression of nephrin in renal biopsy specimens in 35 patients, who were diagnosed as HBV-MN by renal biopsy, was determined by immunohistochemistry and tested by semi-quantitative method. The relationship between the expression of nephrin and clinicopathological data was analyzed.. Among the 35 cases with HBV-MN, 6 were in MN phase I, 20 in MN phase II and 9 in MN phase III. A strong intensity expression of nephrin in normal glomerulus was found along capillary loop of glomerulus, while its expression in HBV-MN patients decreased obviously. There was no significantly difference in the expression of nephrin among the different stages of HBV-MN (P > 0.05). The expression of nephrin in different clinical types was significantly different(P < 0.05). The expression of nephrin in patients with nephrotic syndrome was significantly lower than that in patients without nephrotic syndrome (P < 0.01). The expression of nephrin in different grades of 24-hour urinary protein excretion quantity was significantly different(P < 0.05). There was negative correlation between the expression of nephrin and 24-hour urinary protein excretion quantity(r = -0.378, P < 0.05). In the patients with HBV-MN phase II, the expression of nephrin in patients with nephrotic syndrome was also significantly lower than that in patients without nephrotic syndrome (P < 0.01).. The damage of podocytes emerge in the early stage of HBV-MN and the expression of nephrin in HBV-MN patients, especially in patients with nephrotic syndrome, are significantly down regulated. The descended expression of nephrin in HBV-MN patients may promote the production of proteinuria.

Topics: Adolescent; Adult; Child; Female; Glomerulonephritis, Membranous; Hepatitis B virus; Humans; Male; Membrane Proteins; Middle Aged; Young Adult

We recently reported that nephrin, a major slit-diaphragm protein, is phosphorylated at Y1204 and Y1228 in normal human glomeruli and that phosphorylation decreased significantly in minimal-change nephrosis. These results indicate that phosphorylation of nephrin is important for maintenance of normal podocyte morphology and function. On the other hand, phosphorylation of nephrin was reportedly increased in certain animal models of glomerular injury.. We performed immunofluorescent and immunoelectron staining of phosphorylated nephrin in human kidney biopsy specimens of membranous nephropathy (MN) to investigate whether phosphorylation of nephrin was altered in human MN and whether it correlated with MN staging.. Although aberrant localization of phosphorylated nephrin was detected using immunoelectron microscopy in stage I MN, a decrease in the immunofluorescent intensity of phosphorylated nephrin was not observed in stage I, and only a slight decrease was seen in stages II, III, and IV compared with controls. No significant correlation between nephrin phosphorylation and proteinuria was observed.. Nephrin phosphorylation was not significantly decreased in the early stage of MN.

Topics: Aged; Fluorescent Antibody Technique; Glomerulonephritis, Membranous; Humans; Kidney Glomerulus; Membrane Proteins; Microscopy, Immunoelectron; Middle Aged; Phosphorylation; Proteinuria; Tyrosine

Membranous glomerulonephritis (MGN) is one of the most common causes of nephrotic syndrome in adults. NPHS1 encoding nephrin is a transmembrane protein of the immunoglobulin family. We clarified the relationship between NPHS1 gene polymorphisms and the susceptibility or progression of MGN.. We recruited a cohort of 132 biopsy-diagnosed MGN patients and 257 healthy subjects. Genotyping of three SNPs (rs401824, rs437168 and rs3814995) at chromosome positions 41034749 (5'UTR), 41026259(exon17) and 41034052 (exon 3) was performed using a Taqman SNP genotyping assay.. There was a significant difference in genotype frequency distribution of rs437168 polymorphism between MGN patients and controls. The results also showed that the frequency of the G allele was significantly higher in the patient group. Among the polymorphisms rs437168, rs401824 and rs3814995, no significant haplotype was shown in MGN patients. A stratified analysis revealed that a high disease progression in the AA genotype of rs401824 and GG genotype of rs437168 patients were associated with a low rate of remission.. The presence of the different genotypes of NPHS1 was associated with susceptibility of MGN and the remission of proteinuria during disease progression after the therapy.

Topics: 5' Untranslated Regions; Adult; Aged; Aged, 80 and over; Creatinine; Female; Gene Frequency; Genotype; Glomerulonephritis, Membranous; Haplotypes; Hematuria; Heterozygote; Homozygote; Humans; Immunosuppressive Agents; Male; Membrane Proteins; Middle Aged; Open Reading Frames; Polymorphism, Single Nucleotide; Proteinuria; Taiwan; Treatment Outcome

Membranous nephropathy is a disease that affects the filtering units of the kidney, the glomeruli, and results in proteinuria accompanied by loss of kidney function. Passive Heymann nephritis is an experimental model that mimics membranous nephropathy in humans, wherein the glomerular epithelial cell (GEC) injury induced by complement C5b-9 leads to proteinuria. We examined the role of cytochrome P450 2B1 (CYP2B1) in this complement-mediated sublytic injury. Overexpression of CYP2B1 in GECs significantly increased the formation of reactive oxygen species, cytotoxicity, and collapse of the actin cytoskeleton following treatment with anti-tubular brush-border antiserum (anti-Fx1A). In contrast, silencing of CYP2B1 markedly attenuated anti-Fx1A-induced reactive oxygen species generation and cytotoxicity with preservation of the actin cytoskeleton. Gelsolin, which maintains an organized actin cytoskeleton, was significantly decreased by complement C5b-9-mediated injury but was preserved in CYP2B1-silenced cells. In rats injected with anti-Fx1A, the cytochrome P450 inhibitor cimetidine blocked an increase in catalytic iron and ROS generation, reduced the formation of malondialdehyde adducts, maintained a normal distribution of nephrin in the glomeruli, and provided significant protection at the onset of proteinuria. Thus, GEC CYP2B1 contributes to complement C5b-9-mediated injury and plays an important role in the pathogenesis of passive Heymann nephritis.

Topics: Animals; Antibodies; Cimetidine; Complement Membrane Attack Complex; Cytochrome P-450 CYP2B1; Disease Models, Animal; Enzyme Inhibitors; Gene Silencing; Glomerulonephritis, Membranous; Heymann Nephritis Antigenic Complex; Kidney Glomerulus; Kidney Tubules; Membrane Proteins; Microvilli; Rats; Reactive Oxygen Species

Impaired glomerular endothelial integrity is pivotal in various renal diseases and depends on both the degree of glomerular endothelial injury and the effectiveness of glomerular endothelial repair. Glomerular endothelial repair is, in part, mediated by bone marrow-derived endothelial progenitor cells. Peroxisome proliferator activated receptor-gamma (PPAR-gamma) agonists have therapeutic actions independent of their insulin-sensitizing effects, including enhancement of endothelial progenitor cell function and differentiation. We evaluated the effect of PPAR-gamma agonist rosiglitazone (4 mg.kg(-1).day(-1)) on the course of anti-Thy1-glomerulonephritis in rats. Rosiglitazone limited the development of proteinuria and prevented plasma urea elevation (8.1 +/- 0.4 vs. 12.5 +/- 1.1 mmol/l, P = 0.002). Histologically, inflammatory cell influx was not affected, but rosiglitazone-treated rats did show fewer microaneurysmatic glomeruli on day 7 (26 +/- 3 vs. 41 +/- 5%, P = 0.01) and reduced activation of matrix production with reduced renal cortical transforming growth factor-beta, plasminogen activator inhibitor type 1, and fibronectin-1 mRNA expression. However, bone marrow-derived endothelial cell glomerular incorporation was not enhanced (3.1 +/- 0.4 vs. 3.6 +/- 0.3 cells/glomerular cross section; P = 0.31). Rosiglitazone treatment in nonnephritic rats did not influence proteinuria, urea, or renal histology. In conclusion, treatment with PPAR-gamma agonist rosiglitazone ameliorates the course of experimental glomerulonephritis in a nondiabetic model, but not through enhancing incorporation of bone marrow-derived endothelial cells in the glomerulus.

Topics: Aneurysm; Animals; Blood Pressure; Bone Marrow Transplantation; Cell Movement; Disease Models, Animal; Endothelial Cells; Extracellular Matrix; Fibronectins; Gene Expression; Glomerulonephritis, Membranous; Hypoglycemic Agents; Isoantibodies; Kidney Cortex; Kidney Glomerulus; Male; Membrane Proteins; Plasminogen Activator Inhibitor 1; PPAR gamma; Proteinuria; Rats; Rats, Inbred BN; Rosiglitazone; Stem Cells; Thiazolidinediones; Transforming Growth Factor beta; Urea

The slit diaphragm plays a critical role in maintaining the barrier function of the glomerular capillary wall. The pathogenic mechanism of proteinuria in membranous nephropathy remains uncertain. This study was undertaken to analyze the pathogenic role of slit diaphragm in proteinuria in experimental membranous nephropathy.. The expression and the localization of slit diaphragm-associated molecules (nephrin, podocin, and CD2AP) and other podocyte-associated molecules (podocalyxin and alpha(3) integrin) in passive and active Heymann nephritis were analyzed by immunofluorescence and Western blot analysis. The interaction of slit diaphragm-associated molecules was investigated by the dual-labeling immunofluorescence method. The mRNA expression of these molecules was also analyzed.. Shifts in nephrin and podocin staining patterns, from linear to granular, were detected in the early stages of passive Heymann nephritis. These shifts were not parallel, and the dissociation of these molecules was detected by the dual-labeling immunofluorescence method in passive and active Heymann nephritis. Western blot analyses with sequentially solubilized materials indicated that the nephrin-rich fraction changed from being partly detergent-resistant to being predominantly detergent-soluble. This change did not occur with podocin. Nephrin excreted into urine was already detected in the early stages of passive Heymann nephritis. Decreased mRNA expression of nephrin and podocin was observed before the onset of proteinuria. By contrast, no extensive change in the expression of alpha(3) integrin was observed in this study.. Nephrin is dissociated from podocin and excreted into urine in the early stages of Heymann nephritis. The reduced expression of nephrin and podocin, along with their dissociation, may contribute to the development of proteinuria in Heymann nephritis.

Topics: Adaptor Proteins, Signal Transducing; Amino Acid Sequence; Animals; Blotting, Western; Cytoskeletal Proteins; Female; Fluorescent Antibody Technique; Glomerulonephritis, Membranous; Intracellular Signaling Peptides and Proteins; Male; Membrane Proteins; Molecular Sequence Data; Proteins; Proteinuria; Rabbits; Rats; Rats, Inbred Lew; Rats, Sprague-Dawley; Rats, Wistar; Sheep

For identifying potential diagnostic markers of proteinuric glomerulopathies, glomerular mRNA levels of molecules relevant for podocyte function (alpha-actinin-4, glomerular epithelial protein 1, Wilms tumor antigen 1, synaptopodin, dystroglycan, nephrin, podoplanin, and podocin) were determined by quantitative real-time RT-PCR from microdissected glomeruli. Biopsies from 83 patients with acquired proteinuric diseases were analyzed (minimal change disease [MCD; n = 13], benign nephrosclerosis [n = 16], membranous glomerulopathy [n = 31], focal and segmental glomerulosclerosis [FSGS; n = 9], and controls [n = 14]). Gene expression levels normalized to two different housekeeping transcripts (glyceraldehyde-3-phosphate-dehydrogenase and 18 S rRNA) did not allow a separation between proteinuric disease categories. However, a significant positive correlation between alpha-actinin-4, glomerular epithelial protein 1, synaptopodin, dystroglycan, Wilms tumor antigen 1, and nephrin was found in all analyzed glomeruli, whereas podocin mRNA expression did not correlate. Because varying amounts of housekeeper cDNA per glomerulus can confound expression ratios relevant for a subpopulation of cells, an "in silico" microdissection was performed using a podocyte-specific cDNA as a reference gene. Expression ratio of podocin to synaptopodin, the two genes with the most disparate expression, allowed a robust separation of FSGS from MCD and nephrosclerosis. Segregation of FSGS from MCD via this ratio was confirmed in an independent population of formaldehyde-fixed archival biopsies (MCD, n = 5; FSGS, n = 4) after glomerular laser capture microdissection. In addition, the expression marker was able to predict steroid responsiveness in diagnostically challenging cases of MCD versus FSGS (n = 6). As the above approach can be performed as an add-on diagnostic tool, these molecular diagnostic parameters could give novel information for the management of proteinuric diseases.

Topics: Actinin; Adult; Aged; Biomarkers; Cytoskeletal Proteins; Dystroglycans; Female; Glomerular Mesangium; Glomerulonephritis, Membranous; Humans; Intracellular Signaling Peptides and Proteins; Male; Membrane Glycoproteins; Membrane Proteins; Microfilament Proteins; Middle Aged; Protein Tyrosine Phosphatases; Proteins; Proteinuria; Receptor-Like Protein Tyrosine Phosphatases, Class 3; RNA, Messenger; WT1 Proteins

The onset of proteinuria in passive Heymann nephritis, (PHN), a rat model of human membranous nephropathy (MN), is complement-dependent and is associated with altered podocyte slit diaphragm integrity and dissociation of nephrin from the actin cytoskeleton. These studies examined if complement is responsible for these podocyte changes.. PHN was induced with sheep anti-Fx1A. Controls were injected with normal sheep globulin. A third group was injected with anti-Fx1A and depleted of complement with cobra venom factor. Four days later, proteinuria was measured, slit diaphragm integrity was examined by electron microscopy, nephrin distribution was studied by immunofluorescence, and the glomerular content of nephrin and its association with actin were assessed by sequential extraction of isolated glomeruli and Western blotting.. Four days after immunization, seven out of eight PHN rats were proteinuric, whereas none of the complement depleted group had proteinuria despite similar levels of antibody deposition. Complement depletion preserved slit diaphragm morphology. Immunofluorescence microscopy with an antibody to the extracellular domain of nephrin showed a normal staining pattern in the rats depleted of complement and a shift to a more dispersed and clustered pattern in the PHN group. Western blot analysis of the glomerular extracts showed a significant reduction in the total amount of nephrin and in the fraction of actin-associated nephrin in the PHN group, whereas the amounts in the complement-depleted rats were similar to normal controls.. The onset of proteinuria in the PHN model of MN is coincident with complement-dependent alterations in the association of nephrin with the actin cytoskeleton and loss of podocyte slit diaphragm integrity.

Topics: Actins; Animals; Blotting, Western; Complement System Proteins; Disease Models, Animal; Fluorescent Antibody Technique; Glomerulonephritis; Glomerulonephritis, Membranous; Kidney; Membrane Proteins; Microscopy, Electron; Proteins; Proteinuria; Rats; Tissue Distribution

Topics: Animals; Disease Models, Animal; Glomerulonephritis; Glomerulonephritis, Membranous; Membrane Proteins; Proteins; Rats

Nephrin is a recently identified protein, which is synthesized in the podocytes and localized in the slit diaphragm area. Nephrin is a cell adhesion molecule of the immunoglobulin superfamily, and presumably is a part of the zipper-like structure of the slit membrane. As the mutation of the gene coding nephrin induces congenital nephrotic syndrome of Finnish type, which is a prototype of nephrotic syndrome, it has been suggested that nephrin also plays a role in acquired proteinuric kidney disease.. To address the above issue, the expression of nephrin in acquired human glomerular disease was studied by immunoelectron microscopy employing a polyclonal antibody against nephrin. Four normal human kidneys from nephrectomy specimens and eight kidney biopsy specimens from glomerular disease patients (one minimal change disease, one membranous glomerulonephritis (GN), one membranoproliferative GN, four IgA nephropathy, and one lupus nephritis) were studied. Proteinuria of the patients ranged from 448 to 11725 mg/day. Effacement of the foot processes was observed in all patients.. The study demonstrated that the number and distribution of gold particles in the glomerular region, where the podocyte foot process was well preserved, were similar to that found in normal kidneys; however, gold particles were almost always absent in regions where the foot processes were effaced. The number of gold particles per foot process interspace was not different between normal controls and GN patients; however, the number of gold particles per defined length (1000 nm) of the glomerular basement membrane underlying the foot processes was significantly reduced in GN patients.. Using immunoelectron microscopy, we observed that the expression of nephrin in GN was lower in regions where the foot processes were effaced, and comparable with that of normal controls where the foot process interspaces were preserved. The significance of our observation in the context of proteinuria in acquired GN needs further clarification.

Topics: Adult; Case-Control Studies; Female; Gene Expression; Glomerulonephritis; Glomerulonephritis, IGA; Glomerulonephritis, Membranoproliferative; Glomerulonephritis, Membranous; Humans; Kidney Glomerulus; Lupus Nephritis; Male; Membrane Proteins; Microscopy, Fluorescence; Microscopy, Immunoelectron; Middle Aged; Nephrosis, Lipoid; Proteins

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.

Topics: Adolescent; Adult; Aged; Blotting, Western; Cells, Cultured; Female; Fluorescent Antibody Technique; Gene Expression; Glomerulonephritis, Membranous; Humans; Kidney Glomerulus; Male; Membrane Proteins; Middle Aged; Nephrotic Syndrome; Proteins; Proteinuria; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger