nephrin and Nephrosis--Lipoid

Topics: Animals; Bone Morphogenetic Protein 2; Claudins; Diabetic Nephropathies; Diagnosis, Differential; Glomerulonephritis, IGA; Glomerulosclerosis, Focal Segmental; GTP-Binding Proteins; Humans; Kidney Diseases; Membrane Proteins; Nephrosis, Lipoid; Podocytes; Protein Glutamine gamma Glutamyltransferase 2; Transglutaminases

Remarkable advances have been made in the past decade in understanding the pathophysiology of idiopathic nephrotic syndrome. Although the initiating events leading to the onset of proteinuria still are not well defined, it has become increasingly clear that many glomerular diseases can be classified as podocytopathies, with injury to the podocyte playing a major role in the development and progression of disease. A complex interaction of immune system mediators, slit diaphragm signal transduction, podocyte injury and conformational change, and mediators of apoptosis and fibrosis determine the extent and nature of proteinuria and progression of glomerulosclerosis. New insights into the pathogenesis of idiopathic nephrotic syndrome likely will lead to innovative therapies and new approaches to management and prevention.

Topics: Child; Child, Preschool; Disease Progression; Glomerulosclerosis, Focal Segmental; Humans; Intracellular Signaling Peptides and Proteins; Membrane Proteins; Nephrosis, Lipoid; Nephrotic Syndrome; Podocytes; Proteinuria; Signal Transduction

Idiopathic nephrotic syndrome is the most frequent glomerular disease in children. While genetic analyses have provided new insights into disease pathogenesis through the discovery of several podocyte genes mutated in distinct forms of inherited nephrotic syndrome, the molecular bases of minimal change nephrotic syndrome (MCNS) and focal and segmental glomerulosclerosis (FSGS) with relapse remain unclear. Although immune cell disorders, which may involve both innate and adaptive immunity, appear to play a role in the pathogenesis of steroid sensitive MCNS, the mechanisms by which they induce podocyte dysfunction remain unresolved. It was postulated that podocyte injury results from a circulating factor secreted by abnormal T cells, but the possibility that bipolarity of the disease results from a functional disorder shared by both cell systems is not excluded. MCNS relapses are associated with an activation of the immune system, including an expansion of T and B cell compartments and production of growth factors as well as many cytokines. Dysfunction of T cells is supported by three main findings: (1) inhibition of a type III hypersensitivity reaction ; (2) defects in immunoglobulin switch ; (3) unclassical T helper polarization resulting from transcriptional interference between Th1 and Th2 transcriptional factors.

Topics: Adrenal Cortex Hormones; Cell Membrane Permeability; Cytokines; Glomerulosclerosis, Focal Segmental; Humans; Hypoalbuminemia; Immunosuppressive Agents; Kidney Glomerulus; Lymphocyte Subsets; Membrane Proteins; Nephrosis, Lipoid; Nephrotic Syndrome; Podocytes; Proteinuria; Proto-Oncogene Proteins c-fyn; Recurrence

Topics: Albumins; Animals; Diet, Sodium-Restricted; Glomerular Filtration Rate; Hemopexin; Humans; Immunosuppressive Agents; Membrane Proteins; Nephrosis, Lipoid; Proteinuria; Sodium Potassium Chloride Symporter Inhibitors; Th1 Cells; Th2 Cells

The aim of the review is to discuss recent investigations on the glomerular filtration barrier. The barrier consists of three layers: the vascular endothelium, the glomerular basement membrane and the slit diaphragm located between podocyte foot processes. The main components of the slit diaphragm are nephrin, the product of NPHS1 gene and podocin, the product of NPHS2 gene. Mutations in NPHS1 lead to congenital nephrotic syndrome of the Finnish type (CNF), whereas NPHS2 mutations result in focal segmental glomerulosclerosis (FSGS). In both cases massive proteinuria is accompanied by the effacement of podocyte foot processess. Reduced expression and redistribution of nephrin and podocin are also seen in podocytes of patients with acquired glomerulopathies. The results suggest that those proteins play a pivotal role in the processes responsible for glomerular filtration. Together with podocin and CD2AP (CD2-associated protein), nephrin forms a complex determining the integrity of the slit diaphragm. Its function has not yet been fully understood and the pathways of signal transduction need to be elucidated.

Topics: Adaptor Proteins, Signal Transducing; Cytoskeletal Proteins; Glomerulosclerosis, Focal Segmental; Humans; Intracellular Signaling Peptides and Proteins; Kidney Glomerulus; Membrane Proteins; Nephrosis, Lipoid; Proteins; Proteinuria

In minimal change nephrotic syndrome (MCNS), selective proteinuria is associated with structural alterations of the glomerular epithelial cells, such as effacement of the foot process. Although the pathogenesis of MCNS has not been completely clarified, clinical and experimental observations suggest that it results from T cell dysfunction in the pathogenesis. Recently, it has been proposed that the occurrence of MCNS has been associated with type 2 Th (Th2) lymphocyte-dependent conditions and some vascular permeability factors, which are induced by T cell disorder. In general, MCNS has the good long-term outcome with sustained remission and preserved renal function, because almost cases are responsible for the treatment. However, some patients show frequent relapses or resistance to this treatment and need large doses of immunosuppressive agents for a long time. Therefore, we should be care for the complications associated with prolonged these therapies.

Topics: Drug Hypersensitivity; Humans; Immunosuppressive Agents; Kidney; Lymphoma; Membrane Proteins; Nephrosis, Lipoid; Prednisolone; Prognosis; Proteins; Proteinuria; Th1 Cells; Th2 Cells; Vascular Endothelial Growth Factor A

Failure of the glomerular filtration barrier, primarily by loss of slit diaphragm architecture, underlies nephrotic syndrome in minimal change disease. The etiology remains unknown. The efficacy of B cell-targeted therapies in some patients, together with the known proteinuric effect of anti-nephrin antibodies in rodent models, prompted us to hypothesize that nephrin autoantibodies may be present in patients with minimal change disease.. We evaluated sera from patients with minimal change disease, enrolled in the Nephrotic Syndrome Study Network (NEPTUNE) cohort and from our own institutions, for circulating nephrin autoantibodies by indirect ELISA and by immunoprecipitation of full-length nephrin from human glomerular extract or a recombinant purified extracellular domain of human nephrin. We also evaluated renal biopsies from our institutions for podocyte-associated punctate IgG colocalizing with nephrin by immunofluorescence.. In two independent patient cohorts, we identified circulating nephrin autoantibodies during active disease that were significantly reduced or absent during treatment response in a subset of patients with minimal change disease. We correlated the presence of these autoantibodies with podocyte-associated punctate IgG in renal biopsies from our institutions. We also identified a patient with steroid-dependent childhood minimal change disease that progressed to end stage kidney disease; she developed a massive post-transplant recurrence of proteinuria that was associated with high pretransplant circulating nephrin autoantibodies.. Our discovery of nephrin autoantibodies in a subset of adults and children with minimal change disease aligns with published animal studies and provides further support for an autoimmune etiology. We propose a new molecular classification of nephrin autoantibody minimal change disease to serve as a framework for instigation of precision therapeutics for these patients.

Topics: Adult; Autoantibodies; Child; Child, Preschool; Cohort Studies; Female; Humans; Male; Membrane Proteins; Nephrosis, Lipoid; Podocytes

There are controversies whether Minimal Change Disease (MCD) and Focal and Segmental Glomerulosclerosis (FSGS) are distinct glomerular lesions or different manifestations within the same spectrum of diseases. The uPAR (urokinase-type plasminogen activator receptor) and some slit diaphragm proteins may be altered in FSGS glomeruli and may function as biomarkers of the disease in renal biopsies. Thus, this study aims to evaluate the diagnostic potential of uPAR and glomerular proteins for differentiation between MCD and FSGS in renal pediatric biopsy. Renal biopsies from 50 children between 2 and 18 years old were selected, with diagnosis of MCD (n = 29) and FSGS (n = 21). Control group consisted of pediatric autopsies (n = 15) from patients younger than 18 years old, with no evidences of renal dysfunction. In situ expressions of WT1, nephrin, podocin and uPAR were evaluated by immunoperoxidase technique. Renal biopsy of patients with MCD and FSGS expressed fewer WT1 (p≤0.0001, F = 19.35) and nephrin (p<0.0001; H = 21.54) than patients in the control group. FSGS patients expressed fewer podocin than control (p<0.0359, H = 6.655). FSGS cases expressed more uPAR than each of control and MCD (p = 0.0019; H = 12.57) and there was a positive and significant correlation between nephrin and podocin (p = 0.0026, rS = 0.6502) in these cases. Podocin had sensitivity of 73.3% and specificity of 86.7% (p = 0.0068) and uPAR had sensitivity of 78.9% and specificity of 73.3% (p = 0.0040) for diagnosis of FSGS patients. The main limitation of the study is the limited number of cases due to the difficulty in performing biopsy in pediatric patients. Podocin and uPAR are good markers for FSGS and differentiate these cases from MCD, reinforcing the theory of distinct glomerular diseases. These findings suggest that podocin and uPAR can be used as biomarkers in the routine analysis of renal biopsies in cases of podocytopathies when the lesion (sclerosis) is not sampled.

Topics: Adolescent; Autopsy; Biomarkers; Biopsy; Case-Control Studies; Child; Child, Preschool; Diagnosis, Differential; Female; Gene Expression; Glomerulosclerosis, Focal Segmental; Humans; Intracellular Signaling Peptides and Proteins; Kidney Glomerulus; Male; Membrane Proteins; Nephrosis, Lipoid; Predictive Value of Tests; Receptors, Urokinase Plasminogen Activator; WT1 Proteins

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

Minimal change disease (MCD) is a common pathological type of nephrotic syndrome. Its main histology is the fusion of podocyte foot process. The pathogenesis of MCD is not clear, but previously it was thought to be related to immune mechanism. In recent years more studies show that podocyte injury is the key link in the pathogenesis of MCD. In MCD mouse model and human kidney tissues, the expressions of podocyte slit membrane protein-nephrin and podocin, skeleton protein-synaptopodin are decreased, and the expression of synaptopodin is correlated with the response to hormone therapy. In addition, newest studies focused on another two potocyte associated proteins, CD80 and Angiopoietin-like-4. CD80, a T cell stimulating molecule, is expressed in potocyte. Kappa B gene sequences can be activated by external microbes, antigens through acting potocytes, which can induce the upregulation of CD80 expression, cytoskeletal protein damage and the glomerular filtration rate changes, resulting in proteinuria. Angiopoietin-like-4 can be expressed in normal potocytes, but over-expression of angiopoietin-like-4 may injure the GBM charge barrier and induce the foot process fusion, leading to MCD. However, further studies on the factors inducing CD80 and Angiopoietin-like-4 expression, and the interaction between glomerular basement membrane and the two proteins are needed. Based on the mechanism of MCD, NF-kappa B inhibitors and sialylation therapy would be a novel non-immune therapy for MCD.

Topics: Angiopoietin-Like Protein 4; Angiopoietins; Animals; B7-1 Antigen; Disease Models, Animal; Humans; Intracellular Signaling Peptides and Proteins; Kidney; Membrane Proteins; Mice; Microfilament Proteins; Nephrosis, Lipoid; NF-kappa B; Podocytes

Steroid-resistant nephrotic syndrome (SRNS) is still regarded as a serious disease although treatment with cyclosporine (CSA) has improved outcome. However, the duration of treatment in responders is unclear, and treatment of patients with genetic causes is a matter of debate.. Thirty-six patients with SRNS were studied retrospectively. Median age at presentation was 3.2 (range, 0.06-15.0) and median follow-up 15.5 years (range, 1.8-27.7), respectively; 23 (64%) had focal segmental glomerulosclerosis (FSGS) on biopsy. In 33/36 patients (92%), genetic testing was performed for at least three most common genes known to be mutated in SRNS.. Nineteen patients (53%), especially those with minimal change nephrotic syndrome (MCNS) at initial biopsy (p < 0.002), entered complete remission with CSA monotherapy, including one patient with compound heterozygous NPHS1 and dominant ACTN4 mutation, respectively. Ten patients entered partial remission (28%, all FSGS), including two with NPHS2 mutations. Seven patients (six FSGS, one MCNS) did not respond to treatment. In 15 of 19 responders to CSA, treatment was stopped after a median of 3.1 years (range, 0.5-14) and no further relapses occurred in 11/15 (73%) patients with median follow-up of 9.7 years.. CSA monotherapy is effective in SRNS. Discontinuation of CSA is possible in many patients with complete remission.

Topics: Actinin; Adolescent; Child; Child, Preschool; Cyclosporine; Female; Germany; Glucocorticoids; Humans; Immunosuppressive Agents; Infant; Intracellular Signaling Peptides and Proteins; Kidney; Male; Medication Therapy Management; Membrane Proteins; Nephrosis, Lipoid; Pharmacogenetics; Remission Induction; Retrospective Studies; Secondary Prevention

Podocyte depletion is a characteristic feature of progressive renal failure. We hypothesize that studying the podocyte mRNA level in urinary sediment may provide diagnostic and prognostic information in adult nephrotic syndrome.. We studied 25 patients with minimal change nephropathy (MCN), 25 with focal segmental glomerulosclerosis (FSGS), and 17 healthy controls. The mRNA levels of nephrin, podocin, and synaptopodin in urinary sediment were quantified.. There were significant differences in the urinary sediment nephrin and podocin, but not synaptopodin, mRNA levels between diagnosis groups. Post-hoc analysis further showed that urinary nephrin mRNA levels of the MCN group were lower than those in the control and FSGS groups, although the difference between MCN and FSGS groups did not reach statistical significance. The degree of proteinuria inversely correlated with urinary nephrin mRNA levels in the MCN (r = -0.526, p = 0.007) as well as in the FSGS group (r = -0.521, p = 0.008). For the FSGS group, the rate of renal function decline significantly correlated with baseline urinary synaptopodin mRNA levels (r = -0.496, p = 0.012).. Urinary nephrin and podocin mRNA levels were reduced in patients with MCN and probably FSGS, and the magnitude of reduction correlated with the degree of proteinuria. Urinary synaptopodin mRNA levels correlated with the subsequent rate of renal function decline in patients with FSGS. Our result indicates that urine sediment podocyte mRNA levels provide novel insights in the pathophysiology of nephrotic syndrome and could be useful for risk stratification.

Topics: Adult; Aged; Female; Glomerulosclerosis, Focal Segmental; Humans; Intracellular Signaling Peptides and Proteins; Male; Membrane Proteins; Microfilament Proteins; Middle Aged; Nephrosis, Lipoid; Podocytes; RNA, Messenger

To investigate urinary nephrin and podocalyxin standardized by aquaporin (AQP)-2 using the enzyme-linked immunosorbent assay (ELISA) method in adult nephrotic syndrome (NS) patients.. In 107 adult NS patients (27 proliferative nephritis, 77 non-proliferative, and 3 amyloidosis) undergoing renal biopsy, urinary nephrin, podocalyxin and AQP2 were measured by ELISA. Urinary nephrin and podocalyxin were standardized by AQP2 (neph/AQP and PCX/AQP) and values were compared with 11 healthy controls.. Urinary neph/AQP correlated positively to PCX/AQP (r = 0.51, p < 0.001). Urinary neph/AQP and PCX/AQP were lower in controls than NS patients. Both proliferative and non-proliferative NS patients excreted high urinary neph/AQP and PCX/AQP without a significant difference between them (p > 0.05). Patients with focal segmental glomerular sclerosis (FSGS) excreted higher urinary neph/AQP (p = 0.09) and PCX/AQP (p < 0.05) compared to the other patients. Urinary neph/AQP and PCX/AQP were increased in the immunoglobulin M nephropathy patients. Amyloidosis patients excreted lower neph/AQP and PCX/AQP. The sensitivity was 0.87 and specificity 0.37 when the neph/AQP borderline value of 0.16 was adopted [area under the curve (AUC) = 0.61]. The sensitivity was 0.74 and specificity 0.61 when the PCX/AQP borderline value was 3.06 (AUC = 0.69).. Urinary neph/AQP and PCX/AQP are increased in NS patients, with FSGS patients showing the highest levels. To distinguish FSGS from other NS forms, the measurement of urinary PCX/AQP may be a practical method, and superior to neph/AQP.

Topics: Adolescent; Adult; Aged; Amyloidosis; Aquaporin 2; Case-Control Studies; Child; Enzyme-Linked Immunosorbent Assay; Female; Glomerulonephritis; Humans; Male; Membrane Proteins; Middle Aged; Nephrosis, Lipoid; Nephrotic Syndrome; Podocytes; Sensitivity and Specificity; Sialoglycoproteins; Urine; Young Adult

The precise pathogenic mechanism and role of angiotensin II (Ang II) action in the development of proteinuria in minimal change nephrotic syndrome (MCNS) is uncertain.. The glomerular expressions of the slit diaphragm (SD) molecules nephrin, podocin and NEPH1 in rat puromycin aminonucleoside (PAN) nephropathy, a mimic of MCNS, were analyzed. The effects of Ang II receptor blockade (ARB) (irbesartan 15 mg/kg body weight/day) on proteinuria and on the expression of the SD molecules were analyzed.. mRNA expressions of nephrin, podocin and NEPH1 were decreased to an undetectable level at 1 h. The staining of these SD molecules shifted to a discontinuous pattern, and their intensity was reduced. NEPH1 staining was reduced to an undetectable level on day 10. ARB treatment ameliorated the peak value of proteinuria (237.6 ± 97.0 vs. 359.0 ± 63.3 mg/day, p < 0.05), and prevented the decrease in the mRNA expression of the SD molecules (nephrin 66.96 %, podocin 60.40 %, NEPH1 77.87 % of normal level). The immunofluorescence staining of NEPH1 was restored by ARB. ARB treatment enhanced the expression of NEPH1 of normal rats.. Dysfunction of the SD molecules including NEPH1 is a crucial initiation event of PAN nephropathy. ARB treatment ameliorates proteinuria in PAN nephropathy by inhibiting the reduction of NEPH1 and nephrin. Ang II action regulates the expression of NEPH1 and nephrin in not only the pathological but also physiological state.

Topics: Angiotensin II Type 1 Receptor Blockers; Animals; Biphenyl Compounds; Disease Models, Animal; Disease Progression; Female; Gene Expression Regulation; Intracellular Signaling Peptides and Proteins; Irbesartan; Kidney Glomerulus; Membrane Proteins; Nephrosis, Lipoid; Proteinuria; Puromycin Aminonucleoside; Rats, Wistar; Receptor, Angiotensin, Type 1; Tetrazoles; Time Factors

Glomerular podocyte molecules are involved in the pathogenesis of congenital nephrotic syndrome. However, their role in primary nephrotic syndrome is not clear. This study investigated the expression of nephrin, podocin and synaptopodin in primary nephrotic syndrome.. Eighty-seven patients with primary nephrotic syndrome including minimal change disease (MCD), focal segmental glomerulosclerosis (FSGS), membranous nephropathy (MN) and membranoproliferative glomerulonephritis Type I (MPGN) were included in the study. Glomerular expression of nephrin, podocin and synaptopodin was studied in renal biopsies by immunofluorescence and immunohistochemistry. Correlation of expression with clinical and biochemical parameters was performed.. The pattern of expression for all podocyte proteins in controls was uniform fine granular along the capillary walls towards the visceral epithelial cell aspect. Glomerular expression of nephrin was present in all renal biopsies and was similar to that in controls. Glomerular synaptopodin expression was seen in all MN and MPGN patients, while it was seen in 74 % (17/23) MCD and 93.5 % (29/31) FSGS. Reduced synaptopodin expression showed no correlation with clinical and biochemical factors. Podocin expression was present in 5/23 MCD (22 %), 3/31 FSGS (9.6 %), 13/17 MN (76.4 %) and 13/16 MPGN (81 %) patients. The reduced expression of podocin significantly correlated with the degree of proteinuria (p = 0.032). No correlation with age, gender and serum creatinine level was observed.. Reduction of glomerular podocin expression found in MCD and FSGS is related to the amount of proteinuria. Our findings suggest that alteration in podocyte phenotype may not be a primary event and may reflect the degree of podocyte injury in primary nephrotic syndrome.

Topics: Adolescent; Adult; Creatinine; Glomerulonephritis, Membranoproliferative; Glomerulosclerosis, Focal Segmental; Humans; Intracellular Signaling Peptides and Proteins; Kidney Glomerulus; Male; Membrane Proteins; Microfilament Proteins; Middle Aged; Nephrosis, Lipoid; Nephrotic Syndrome; Podocytes; Proteinuria

To explore the correlation between Chinese medicine (CM) syndromes and the NPHS1 gene and NPHS2 gene polymorphism as well as corticosteroid sensitivity in patients with minimal change disease (MCD).. A total of 94 MCD patients were recruited, including 58 steroid-sensitive nephritic syndrome (SSNS) patients and 36 steroid-resistant nephritic syndrome (SRNS) patients. Genomic DNA was obtained from peripheral blood lymphocytes and sequence analysis of single nucleotide polymorphisms (SNPs) in the genes was performed.. (1) The SNPs of G349A-3 in NPHS1 gene was found in MCD, but the SNPs of G686A-5 and C695T-5 in NPHS2 gene were not discovered in MCD. (2) When comparing the frequency of genotype AA and allele A in NPHS1 gene (G349A-3), genotype AA and allele A were higher in the SRNS group than in the SSNS group (P < 0.05). (3) When compared with the SRNS group, qi yang deficiency syndrome had a higher incidence in the SSNS group, and yin deficiency syndrome and qi-yin deficiency syndrome had a less incidence in the SSNS, but with no statistical difference (P > 0.05). The rheumatism syndrome had a higher incidence in the SSNS group (P < 0.05). The blood stasis syndrome had a lower incidence in the SSNS with statistical difference (P < 0.05). (4) There was no statistical difference in the correlation between GG, AA, GA and CM syndromes (P > 0.05).. Homozygous mutations of AA and allele A in NPHS1 gene were correlated to SRNS patients of MCD. Rheumatism syndrome patients were prone to be sensitive to corticosteroids, while patients of blood stasis syndrome were prone to be insensitive to corticosteroids. We didn't discover the correlation between NPHS1 gene polymorphism and CM syndrome distribution.

Topics: Adolescent; Adrenal Cortex Hormones; Adult; Aged; Female; Genotype; Homozygote; Humans; Intracellular Signaling Peptides and Proteins; Male; Medicine, Chinese Traditional; Membrane Proteins; Middle Aged; Nephrosis, Lipoid; Nephrotic Syndrome; Polymorphism, Single Nucleotide; Yang Deficiency; Yin Deficiency; Young Adult

Podocyte proteins are involved in the pathogenesis of glomerular kidney disease (GKD). However, there is little information on messenger RNA (mRNA) expression patterns of B7-1 and NPHS1 in urinary sediment of patients with GKD. The objective of this study was to analyse the gene expression of B7-1 in urinary sediment and correlate it with the expression of podocyte-specific genes in patients with GKD.. Adult patients with proliferative and non-proliferative GKD, proteinuria and stable renal function, were included. A group of healthy subjects was used to determine normal levels of urinary markers and to obtain reference RNA. Biochemical, clinical and experimental procedures included measurement of creatinine level and total urinary protein, renal biopsy, identification of urinary podocytes, gene expression analysis of B7-1, NPHS1, NPHS2 and SyNPO genes and urinary B7-1 protein analysis by enzyme-linked immunosorbent assay.. Between June 2006 and November 2009, 69 patients with GKD (median age: 46 ± 15 years, 64% men) and 14 healthy subjects (median age: 34 ± 12 years, 43% men) were included. In both groups, urinary mRNA levels of B7-1 and NPHS1 were significantly higher in patients with GKD compared to healthy subjects (P = 0.050 and P = 0.008, respectively). Regarding GKD subtypes, patients with focal segmental glomerulosclerosis (FSGS), but not patients with minimal change disease (MCD), had a significantly higher mRNA expression of B7-1 and NPHS1 than healthy subjects (P = 0.012 and P = 0.030, respectively). Patients with MCD had a significantly lower NPHS1 mRNA expression than patients with FSGS (P = 0.012). The B7-1:NPHS1 urinary mRNA ratio was significantly higher in patients with MCD compared with patients with FSGS (P = 0.027).. mRNA expression analysis of B7-1 and NPHS1 in urinary sediment may be useful to differentiate between different histologic subtypes of GKD, particularly between MCD and FSGS.

Topics: Adult; Diagnosis, Differential; Female; Glomerulosclerosis, Focal Segmental; Humans; Inducible T-Cell Co-Stimulator Ligand; Male; Membrane Proteins; Middle Aged; Nephrosis, Lipoid; Podocytes; Prospective Studies; RNA, Messenger

Several proteins constituting the slit diaphragm are considered important for maintaining capillary wall permselectivity. Early intervention with blockers of angiotensin II receptors (AR) and mineralocorticoid receptors (MR) is effective against proteinuria in models of chronic hypertensive and protein-induced renal damage. However, the effects of AR and/or MR blockers in a model of acute nephrotic syndrome remain unknown. The effects of AR and MR blockers were examined in puromycin aminonucleoside (PAN)-treated rats.. Six week old male Sprague-Dawley (SD) rats were injected with PAN or vehicle and assigned to groups as follows: vehicle (group C); PAN (group P); PAN followed 3 days later by administration of the MR blocker, eplerenone (group MR), and by the AR blocker, losartan (group AR). Blood pressure and urinary protein excretion were measured and all rats were killed for immunohistochemical investigation on day 14 after PAN administration.. Blood pressure did not change throughout the study period. Proteinuria was decreased in groups MR and AR compared with group P (on day 14 after PAN administration, respectively; group P vs AR, P < 0.01; group P vs MR, P < 0.05). Nephrin, podocin and podocalyxin staining was preserved in the glomeruli of groups MR and AR compared with group P.. The MR and AR blockers decreased proteinuria in the acute model of nephrotic syndrome with preserved expression of glomerular podocyte protein independently of blood pressure.

Topics: Angiotensin II Type 1 Receptor Blockers; Animals; Blood Pressure; Disease Models, Animal; Eplerenone; Fluorescent Antibody Technique; Intracellular Signaling Peptides and Proteins; Losartan; Male; Membrane Proteins; Mineralocorticoid Receptor Antagonists; Nephrosis, Lipoid; Podocytes; Proteinuria; Puromycin Aminonucleoside; Rats; Rats, Sprague-Dawley; Sialoglycoproteins; Spironolactone; Time Factors

To investigate the effect of bone mesenchymal stem cell (BMSC) transplantation on repair of glomerular podocytes and on the Nephrin expression in rats with puromycin aminonucleoside (PAN) -induced nephrosis.. Forty-five Sprague-Dawley rats were randomly divided into three groups (n=15 each): a nephrosis model group that received a single intraperitoneal injection of PAN (0.15 mg/g); a BMSC transplantation group that received a single intraperitoneal injection of PAN (0.15 mg/g) followed by BMSC transfusion; a control group that received a single intraperitoneal injection of normal saline. Ten days after injection, the rats were sacrificed. The 24 hrs urinary protein content and serum albumin and cholesterol levels were measured 24 hrs before sacrifice. Changes of glomerular podocytes were observed under an electron microscope. Brdu labeled positive cells in kidneys were measured by immunohistochemical technology. RT-PCR and Western blot were used to assess the expression of mRNA and protein of Nephrin.. In the nephrosis model group, urinary protein and blood cholesterol contents increased, plasma albumin content decreased compared with those in the control group. Extensive fusion of podocyte foot processes was observed in the nephrosis model group. The BMSC transplantation group had decreased urinary protein and blood cholesterol contents and increased plasma albumin content compared with the nephrosis model group. Fusion of podocyte foot processes was also improved. Brdu labeled positive cells were seen in kidneys in the BMSC transplantation group, but not in the nephrosis model and the control groups. Nephrin mRNA and protein expression decreased significantly in the nephrosis model group compared with that in the control group. The BMSC transplantation group had increased Nephrin mRNA and protein expression compared with the nephrosis model group.. BMSCs can repair glomerular podocytes in PAN-induced nephrosis rats, and the changes of Nephrin expression may be involved in the process.

Topics: Animals; Bromodeoxyuridine; Kidney; Male; Membrane Proteins; Mesenchymal Stem Cell Transplantation; Nephrosis, Lipoid; Podocytes; Puromycin Aminonucleoside; Rats; Rats, Sprague-Dawley; Reverse Transcriptase Polymerase Chain Reaction

Nephrin is an essential structural component of the glomerular slit diaphragm (SD), a highly organized intercellular junction that constitutes the ultrafiltration barrier of the kidney. Recent studies have identified two additional nephrin-interacting SD proteins (NEPH1 and NEPH2), suggesting that the zipper-like pattern of the SD is formed through complex intra- and intermolecular interactions of these proteins. However, the complexity of the SD structure suggests that additional SD components remain to be discovered. In this study, we identified galectin-1 (Gal-1) as a new component of the SD, binding to the ectodomain of nephrin. Using dual-immunofluorescence and confocal microscopy and dual-immunoelectron microscopy, we found Gal-1 co-localizing with the ectodomain of nephrin at the SD in normal human kidney. By immunoprecipitation and surface plasmon resonance, we confirmed a direct molecular interaction between Gal-1 and nephrin. Moreover, recombinant Gal-1 induced tyrosine phosphorylation of the cytoplasmic domain of nephrin and activation of the extracellular signal-regulated kinase 1/2 in podocytes. We also showed that podocytes are a major site of biosynthesis of Gal-1 in the glomerulus and that the normal expression patterns and levels of Gal-1 are altered in patients with minimal change nephrotic syndrome. Finally, in puromycin aminonucleoside-induced rat nephrosis, an apparent reduction in the levels of Gal-1 and nephrin around the onset of heavy proteinuria was also revealed. Our data present Gal-1 as a new extracellular ligand of nephrin localized at the glomerular SD, and provide further insight into the complex molecular organization, interaction, and structure of the SD, which is an active site of intracellular signaling necessary for podocyte function.

Topics: Animals; Cell Line, Transformed; Disease Models, Animal; Female; Fluorescent Antibody Technique, Indirect; Galectin 1; Humans; Kidney; Membrane Proteins; Microscopy, Confocal; Microscopy, Fluorescence; Microscopy, Immunoelectron; Mitogen-Activated Protein Kinase 3; Nephrosis, Lipoid; Phosphorylation; Podocytes; Rats; Recombinant Proteins; Tyrosine

Frequently relapsing and steroid-dependent minimal-change nephrotic syndrome (MCNS) that originates in childhood can persist after puberty in >20% of patients. These patients require immunosuppressive treatment during several decades of their life. We examined long-term adverse effects of persistent nephrotic syndrome and immunosuppressive medications, focusing on renal function, growth, obesity, osteoporosis, hypertension, ocular complications, and fertility in adult patients with biopsy-proven childhood-onset MCNS. Molecular analysis was performed to evaluate a possible association of a complicated course of MCNS with podocyte gene mutations.. We performed a prospective clinical examination of 15 adult patients that included serum and urine analysis; dual-energy x-ray absorptiometry; ophthalmologic examination; semen examination; and molecular analysis of NPHS1, NPHS2, CD2AP, and ACTN4 genes.. All patients had normal GFR. Most frequent long-term complications were hypertension (in seven of 15 patients) and osteoporosis in one third of patients. Oligozoospermia was found in one patient, reduced sperm motility in four of eight patients, and teratozoospermia in six of eight patients. Ophthalmologic examination revealed myopia in 10 of 15 patients and cataract in three of 15 patients.. Children with MCNS that persists after puberty are at risk for complications such as osteoporosis, hypertension, cataract, and sperm abnormalities. Our study underscores a need for more effective and less toxic therapies for relapsing MCNS.

Topics: Absorptiometry, Photon; Adolescent; Adult; Biopsy; Bone Density; Child; Child, Preschool; Eye Diseases; Female; Fertility; Humans; Infant; Intracellular Signaling Peptides and Proteins; Kidney; Male; Membrane Proteins; Nephrosis, Lipoid; Recurrence

IL-13 has been implicated in the pathogenesis of minimal-change nephrotic syndrome. This study aimed to investigate the role of IL-13 on the development of proteinuria and expression of podocyte-related genes that are associated with nephrotic syndrome. IL-13 was overexpressed in Wistar rats through transfection of a mammalian expression vector cloned with the rat IL-13 gene, into the quadriceps by in vivo electroporation. Serum IL-13, albumin, cholesterol, and creatinine and urine albumin were measured serially. Kidneys were harvested after day 70 for histology and electron microscopy. Glomerular gene expression of nephrin, podocin, dystroglycan, B7-1, and IL-13 receptor subunits were examined using real-time PCR with hybridization probes and expressed as an index against beta-actin. Protein expression of these molecules was determined by immunofluorescence staining. The IL-13-transfected rats (n = 41) showed significant albuminuria, hypoalbuminemia, and hypercholesterolemia when compared with control rats (n = 17). No significant histologic changes were seen in glomeruli of IL-13-transfected rats. However, electron microscopy showed up to 80% of podocyte foot process fusion. Glomerular gene expression was significantly upregulated for B7-1, IL-4Ralpha, and IL-13Ralpha2 but downregulated for nephrin, podocin, and dystroglycan. Immunofluorescence staining intensity was reduced for nephrin, podocin, and dystroglycan but increased for B7-1 and IL-4Ralpha in IL-13-transfected rats compared with controls. In conclusion, these results suggest that IL-13 overexpression in the rat could lead to podocyte injury with downregulation of nephrin, podocin, and dystroglycan and a concurrent upregulation of B7-1 in the glomeruli, inducing a minimal change-like nephropathy that is characterized by increased proteinuria, hypoalbuminemia, hypercholesterolemia, and fusion of podocyte foot processes.

Topics: Animals; Animals, Genetically Modified; B7-1 Antigen; Dystroglycans; Electroporation; Female; Gene Expression Regulation; Interleukin-13; Interleukin-13 Receptor alpha2 Subunit; Interleukin-4 Receptor alpha Subunit; Intracellular Signaling Peptides and Proteins; Kidney; Membrane Proteins; Nephrosis, Lipoid; Rats; Rats, Wistar

There have been many exciting advances in our understanding of genetic causes of nephrotic syndrome since 1998 when nephrin was first found. The mRNA expressions of nephrin and CD2AP were studied by quantitative real-time polymerase chain reaction (PCR) in aspirated renal biopsy tissues from 9 subjects with minimal change nephrotic syndrome (MCNS), 6 with primary IgA nephropathy (IgAN), and 15 controls. Protein expression of nephrin, podocin, and CD2AP were analyzed by immunohistochemistry, indirect immunofluorescence, and laser confocal microscope. Compared with controls, the CD2AP mRNA level was significantly downregulated in renal samples from MCNS and IgAN patients (p=0.001 in MCNS, p=0.046 in IgAN), though no significant downregulation was found in the mRNA level of nephrin (p=0.346 in MCNS, p=0.311 in IgAN). The expression levels of protein CD2AP and nephrin were significantly reduced in MCNS and IgAN (MCNS: nephrin, p=0.034, CD2AP, p=0.005; IgAN: nephrin, p=0.021, CD2AP, p=0.025). The podocin staining did not differ significantly between controls and disease groups (p value 0.340 and 0.787, respectively). The results suggest that transcript and translation expression changes of nephrin and CD2AP may have pathogenetic roles in some patients with MCNS and IgAN in Chinese, though no correlation was found in podocin with proteinuria in this study.

Topics: Adaptor Proteins, Signal Transducing; Child; China; Cytoskeletal Proteins; Female; Glomerulonephritis, IGA; Humans; Immunohistochemistry; Intracellular Signaling Peptides and Proteins; Kidney; Male; Membrane Proteins; Nephrosis, Lipoid; Polymerase Chain Reaction; RNA, Messenger

The pathogenesis of minimal change nephrotic syndrome (MCNS) is still unknown. We performed a clinical and genetic evaluation of 104 adults (mean age 35 years) who presented with MCNS in childhood (mean follow-up 30 years). Clinical data and the present health status were evaluated. Also, the genes encoding the four major slit diaphragm proteins, nephrin, podocin, Neph1 and CD2-associated protein were sequenced in 38 patients with MCNS of varying severity. MCNS presented at the mean age of 5 years, and 80% of the patients relapsed 1-28 (median 3) times during childhood. The 14 subjects (14%) who had proteinuric episodes still in adulthood had a refractory disease already as children. The participants did not show a strong tendency for allergy or immune diseases, and no familial clustering of MCNS was observed. The genetic analyses revealed heterozygous amino acid changes in nephrin and podocin in 10 of the 38 patients studied. On the other hand, the genes coding for Neph1 and CD2AP were highly conserved and no amino acid substitutions were detected. In conclusion, MCNS is a multifactorial disease, in which genetics play a minor role. Allelic variants of the podocyte proteins may, however, modify the phenotype in occasional individuals.

Topics: Adaptor Proteins, Signal Transducing; Adult; Creatinine; Cytoskeletal Proteins; Female; Humans; Intracellular Signaling Peptides and Proteins; Male; Membrane Proteins; Nephrosis, Lipoid; Proteins; Risk Factors

Nephrin is a podocyte adhesion molecule located at the slit diaphragm between adjacent glomerular epithelial cells. Mutations in the gene encoding nephrin result in the absence of nephrin or alterations in nephrin causing massive proteinuria in patients with congenital nephrotic syndrome. Given the importance of nephrin to the structural integrity of the glomerular filtration barrier, we postulated that it might also be altered in acquired forms of nephrotic syndrome (NS). To test this hypothesis, frozen kidney biopsy sections from 29 pediatric patients with acquired NS and 5 controls were examined for expression of nephrin. The pathological diagnoses were minimal change disease (MCNS) (19) and focal segmental glomerulosclerosis (FSGS) (10). To determine if nephrin expression differed between children and adults with NS, 10 adult patients and 3 controls were also examined. Nephrin expression was evaluated by immunoperoxidase staining with a monoclonal antibody against the extracellular FnIII portion of human nephrin. In all cases, nephrin expression was seen along the glomerular basement membrane in a finely granular/linear pattern. Expression of nephrin was similar to controls in all 19 patients with MCNS and all 10 patients with FSGS. Areas of sclerosis in patients with FSGS did not demonstrate nephrin expression. A distinctly granular pattern to nephrin expression was seen in adult patients with NS as well as controls. These findings suggest that an alteration in nephrin expression is not a feature of acquired forms of NS in childhood.

Topics: Adolescent; Biopsy; Child; Child, Preschool; Female; Glomerulosclerosis, Focal Segmental; Humans; Immunohistochemistry; Infant; Kidney Glomerulus; Male; Membrane Proteins; Nephrosis, Lipoid; Proteins

Minimal change nephrotic syndrome (MCNS) is a major problem in pediatric nephrology. While the pathogenesis of MCNS is not known, the latest discoveries in the genetic diseases indicate that glomerular epithelial cells (podocytes) and the slit diaphragm play a primary role in development of proteinuria. Because nephrin is known to be a major component of the slit diaphragm, we analyzed the structure of nephrin gene (NPHS1) in patients with MCNS of different severity.. Clinical data and DNA samples were collected from 25 adults who had biopsy-proven MCNS in childhood. A direct sequencing was performed to all 29 exons of the NPHS1 gene. The significance of the findings was evaluated by similar analysis of DNA samples from 25 healthy control patients.. The analysis of NPHS1 revealed no specific MCNS-associated mutation. However, 5 of the 25 MCNS patients had heterozygous allelic variants leading to nonconservative amino acid substitutions not previously reported (G879R; R800C; T294I; A916S). One of the five patients also had the Fin-major mutation, and two had new, conservative amino acid substitutions (S786N; A342G). Three of the five patients were classified as steroid sensitive, one was an early nonresponder, and one patient showed clear resistance to steroid treatment. Six known polymorphic changes in NPHS1 were also found, three of them leading to amino acid changes. The number of allelic variants was high both in MCNS patients and control patients (mean 3.0 and 2.6).. The results suggest that genetic changes in nephrin may have a pathogenetic role in some patients with MCNS.

Topics: Adolescent; Adult; Alleles; Amino Acid Substitution; Case-Control Studies; Child; Child, Preschool; Drug Resistance; Female; Genetic Variation; Heterozygote; Humans; Infant; Male; Membrane Proteins; Mutation; Nephrosis, Lipoid; Polymorphism, Genetic; Proteins; Steroids

Recently, nephrin, podocin, alpha-actinin, and WT1, which are located at the slit diaphragm and expressed by the podocyte, were found to be causative in congenital/familial nephrotic syndrome (NS), but their role in acquired NS remains unclear. We studied their expression in NS with the aim of disclosing their possible role in the development of proteinuria. Immunofluorescence, confocal microscopy, and image analysis were used to study the expression and the distribution in 19 children with primary NS, 9 with isolated hematuria, and 9 controls. All the children with NS presented with heavy proteinuria and foot process effacement was identified by electron microscopy. No proteinuria and foot process effacement was seen in the group with hematuria. A dramatic decrease of podocin expression was found in NS (86.66+/-22.74) compared with control groups ( P=0.014). Furthermore, we also found the pattern of distribution of nephrin, podocin, and alpha-actinin changed in children with NS. In conclusion, a dramatic decrease of podocin expression and abnormal distribution of nephrin, podocin, and alpha-actinin were found in children with NS. No differences were found in children with isolated hematuria, suggesting involvement of these molecules in the development of proteinuria in primary NS.

Topics: Actinin; Adolescent; Case-Control Studies; Child; Female; Glomerulonephritis, IGA; Hematuria; Humans; Intracellular Signaling Peptides and Proteins; Male; Membrane Proteins; Nephrosis, Lipoid; Nephrotic Syndrome; Proteins; Tissue Distribution; WT1 Proteins

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