nephrin and Kidney-Failure--Chronic

Topics: Actinin; Actins; Adaptor Proteins, Signal Transducing; Angiotensin II Type 1 Receptor Blockers; Animals; Apoptosis; Cytoskeletal Proteins; Humans; Intracellular Signaling Peptides and Proteins; Kidney Failure, Chronic; Membrane Proteins; Podocytes; Proteins; Proteinuria; Receptor, Angiotensin, Type 1; Tetrazoles; Valine; Valsartan

Focal and segmental glomerulosclerosis (FSGS) is a pathologic entity that is a common and increasing cause of end-stage renal disease. Typical manifestations include proteinuria, hypertension, worsening renal insufficiency, and, frequently, renal failure. The etiology, however, remains unknown in a majority of patients. There is an estimated recurrence rate of 30% to 40% in renal transplant patients, suggesting that the pathogenesis is not solely a result of intrinsic kidney disease. Although some of its characteristics have been reported, the precise identification of a circulating factor associated with FSGS has not been made. Remarkable progress has been made in recent years regarding biologic mechanisms surrounding FSGS and proteinuria. Insight into the pathogenesis of FSGS has been gained through the study of hereditary forms of FSGS and nephrotic syndromes. Mutations in cytoskeletal proteins that affect podocyte structure have been the target until recently. Here we review the current understanding of this glomerular disease and areas for future concentration.

Topics: Adaptor Proteins, Signal Transducing; Biomarkers; Cytoskeletal Proteins; Disease Progression; Glomerulosclerosis, Focal Segmental; Humans; Intracellular Signaling Peptides and Proteins; Kidney Failure, Chronic; Membrane Proteins; Risk Factors; src Homology Domains; TRPC Cation Channels; TRPC6 Cation Channel

Chronic kidney diseases are emerging as a worldwide public health problem. Clarification of the mechanisms underlying progression of proteinuric nephropathies received significant input from the generation of transgenic and knockout animals and from novel approaches to block mediators of injury. Reviewed here are advances in animal models used as a tool to address some relevant questions to the pathophysiology of human chronic nephropathies.. Gene targeting in rodents identified podocyte loss as central event in the development of glomerulosclerosis. The trigger is dysfunction or absence of podocyte molecules that stabilize the slit diaphragm or anchor foot processes to the basement membrane. Sustained injury of the glomerular barrier to proteins is transmitted to the tubulointerstitial compartment leading to inflammation and fibrosis. Blocking NF-kappaB activity and chemokine signals in the kidney effectively interrupts such process. Growth factors produced by tubular cells and inflammatory cells contribute to interstitial fibrogenesis via myofibroblast activation.. Development of genetically engineered animals and techniques to specifically manipulate cellular mediators has highlighted the determinants of glomerulosclerosis and tubulointerstitial injury. This knowledge will provide basis for novel interventions to protect the podocyte in chronic progressive glomerulopathies and to halt renal scarring and loss of function.

Topics: Animals; Disease Progression; Humans; Kidney Failure, Chronic; Kidney Glomerulus; Membrane Proteins; Models, Animal; Podocytes

Neonatal-onset Denys-Drash syndrome (NODDS) is a distinctive clinical entity and has a poor renal and life outcome. Early diagnosis of NODDS is important for managing disorders of sexual development and determining assigned gender. Although patients with NODDS and congenital nephrotic syndrome of the Finnish type (CNF) present with nephrotic syndrome in neonatal life or infancy, the clinical course of NODDS and factors distinguishing these diseases at onset is unknown.. We performed a retrospective cohort study of patients with NODDS and CNF between 1997 and 2017. Patients with nephrotic syndrome and WT1 or NPHS1 mutations with neonatal onset (within 30 days) were eligible.. We studied eight patients with NODDS and 15 with CNF. The median serum creatinine level at onset in the NODDS group was significantly higher (1.85 mg/dL) than that in the CNF group (0.15 mg/dL; P = 0.002). The median placental/fetal weight ratio in the NODDS and CNF group was 41.8% and 21.0%, respectively (P = 0.001). Kaplan-Meier analysis showed that the median number of days for progression to ESRD from onset in the NODDS and CNF groups was 6 and 910 days, respectively (P < 0.001). All patients in the NODDS group were alive at follow-up. Only one patient in the CNF group died of cardiac complications during follow-up.. CNS, renal dysfunction at onset, and a relatively large placenta are prominent signs of NODDS. Prognosis for patients with NODDS is satisfactory if appropriate and active management is performed.

Topics: Adolescent; Age of Onset; Child; Child, Preschool; Denys-Drash Syndrome; Disease Progression; Genetic Predisposition to Disease; Humans; Infant; Infant, Newborn; Kidney Failure, Chronic; Membrane Proteins; Mutation; Nephrotic Syndrome; Phenotype; Renal Dialysis; Retrospective Studies; Risk Factors; Tokyo; WT1 Proteins

Podocyte depletion in the kidney is associated with end-stage kidney disease (ESKD). Pre-eclampsia (PE) increases the risk of ESKD in later life. This study was performed to determine whether nephrinuria (soluble nephrin in the urine) is correlated with proteinuria and/or podocyturia (podocytes in the urine) in PE women.. Eighty-three urine samples, consisting of 45 and 38 samples from 27 normotensive and nine PE women, respectively, underwent simultaneous determination of nephrin, protein, and creatinine concentrations in the urine supernatant and quantitative analysis of podocyte-specific protein mRNA expression. This included podocin (Pod-mRNA) and nephrin (Nep-mRNA), using real-time polymerase chain reaction in the pelleted urine. Nephrinuria and proteinuria were corrected by creatinine concentration. Pod- and Nep-mRNA expression levels were corrected by GAPDH.. Nephrinuria, proteinuria, Pod-mRNA expression, and Nep-mRNA expression all increased with advancing gestation in PE women, while not in normotensive women. The nephrinuria was strongly correlated with proteinuria (R = 0.901, P <  0.001), Pod-mRNA expression level (R = 0.824, P < 0.001), and Nep-mRNA expression level (R  =  0.724, P <  0.001) in urine samples from PE women, while the nephrinuria was significantly correlated with proteinuria alone (R  =  0.419, P <  0.005) in urine samples from normotensive women.. Nephrinuria reflected well the degrees of proteinuria and podocyturia in PE women. This suggested that increased nephrinuria/proteinuria was associated with podocyte loss in the kidneys of PE women.

Topics: Adult; Creatine; Female; Gestational Age; Humans; Kidney Failure, Chronic; Membrane Proteins; Podocytes; Pre-Eclampsia; Pregnancy; Proteinuria; Risk Factors; Young Adult

Steroid Resistant Nephrotic Syndrome (SRNS) in children and young adults has differing etiologies with monogenic disease accounting for 2.9-30% in selected series. Using whole exome sequencing we sought to stratify a national population of children with SRNS into monogenic and non-monogenic forms, and further define those groups by detailed phenotypic analysis. Pediatric patients with SRNS were identified via a national United Kingdom Renal Registry. Whole exome sequencing was performed on 187 patients, of which 12% have a positive family history with a focus on the 53 genes currently known to be associated with nephrotic syndrome. Genetic findings were correlated with individual case disease characteristics. Disease causing variants were detected in 26.2% of patients. Most often this occurred in the three most common SRNS-associated genes: NPHS1, NPHS2, and WT1 but also in 14 other genes. The genotype did not always correlate with expected phenotype since mutations in OCRL, COL4A3, and DGKE associated with specific syndromes were detected in patients with isolated renal disease. Analysis by primary/presumed compared with secondary steroid resistance found 30.8% monogenic disease in primary compared with none in secondary SRNS permitting further mechanistic stratification. Genetic SRNS progressed faster to end stage renal failure, with no documented disease recurrence post-transplantation within this cohort. Primary steroid resistance in which no gene mutation was identified had a 47.8% risk of recurrence. In this unbiased pediatric population, whole exome sequencing allowed screening of all current candidate genes. Thus, deep phenotyping combined with whole exome sequencing is an effective tool for early identification of SRNS etiology, yielding an evidence-based algorithm for clinical management.

Topics: Adolescent; Age of Onset; Child; Child, Preschool; Cohort Studies; Disease Progression; Exome; Female; Genetic Association Studies; Genetic Predisposition to Disease; Genomics; Heredity; High-Throughput Nucleotide Sequencing; Humans; Infant; Intracellular Signaling Peptides and Proteins; Kaplan-Meier Estimate; Kidney; Kidney Failure, Chronic; Male; Membrane Proteins; Mutation; Nephrotic Syndrome; Pedigree; Phenotype; Precision Medicine; Predictive Value of Tests; Prognosis; Registries; Risk Factors; United Kingdom; WT1 Proteins; Young Adult

Treatment of congenital nephrotic syndrome (CNS) and steroid-resistant nephrotic syndrome (SRNS) is demanding, and renal prognosis is poor. Numerous causative gene mutations have been identified in SRNS that affect the renal podocyte. In the era of high-throughput sequencing techniques, patients with nongenetic SRNS frequently escape the scientific interest. We here present the long-term data of the German CNS/SRNS Follow-Up Study, focusing on the response to cyclosporin A (CsA) in patients with nongenetic versus genetic disease.. Cross-sectional and longitudinal clinical data were collected from 231 patients with CNS/SRNS treated at eight university pediatric nephrology units with a median observation time of 113 months (interquartile range, 50-178). Genotyping was performed systematically in all patients.. The overall mutation detection rate was high at 57% (97% in CNS and 41% in SRNS); 85% of all mutations were identified by the analysis of three single genes only (NPHS1, NPHS2, and WT1), accounting for 92% of all mutations in patients with CNS and 79% of all mutations in patients with SRNS. Remission of the disease in nongenetic SRNS was observed in 78% of patients after a median treatment period of 2.5 months; 82% of nongenetic patients responded within 6 months of therapy, and 98% of patients with nongenetic SRNS and CsA-induced complete remission (normalbuminemia and no proteinuria) maintained a normal renal function. Genetic SRNS, on the contrary, is associated with a high rate of ESRD in 66% of patients. Only 3% of patients with genetic SRNS experienced a complete remission and 16% of patients with genetic SRNS experienced a partial remission after CsA therapy.. The efficacy of CsA is high in nonhereditary SRNS, with an excellent prognosis of renal function in the large majority of patients. CsA should be given for a minimum period of 6 months in these patients with nongenetic SRNS. In genetic SRNS, response to CsA was low and restricted to exceptional patients.

Topics: Adolescent; Austria; Biopsy; Child; Child, Preschool; Cross-Sectional Studies; Cyclosporine; Disease Progression; DNA Mutational Analysis; Female; Genetic Predisposition to Disease; Germany; Humans; Immunosuppressive Agents; Infant; Intracellular Signaling Peptides and Proteins; Kidney; Kidney Failure, Chronic; Longitudinal Studies; Male; Membrane Proteins; Mutation; Nephrotic Syndrome; Phenotype; Recovery of Function; Remission Induction; Risk Factors; Time Factors; Treatment Outcome; WT1 Proteins

Renal transplantation is the optimal renal replacement therapy (RRT) in children, but some primary diseases can recur after transplantation, and recurrence accounts for a significant proportion of graft losses, being second only to acute rejection. The risk of disease recurrence is highest among patients with idiopathic focal segmental glomerulosclerosis (FSGS), presumably due to a circulating permeability factor. Less is clear about the genetic forms of FSGS, where the data regarding the frequency of recurrence are rather conflicting. We present a 12-year-old girl with rapidly progressive FSGS and end-stage renal disease in her native kidneys associated with heterozygous mutations in NPHS1 and in NPHS2, suffering from early post-transplant recurrence. On the basis of reviewed literature, and until further and more conclusive evidence considering pathogenicity is provided, we propose that FSGS patients with heterozygous mutations in NPHS1 or NPHS2 should be considered as having idiopathic FSGS, and post-transplant recurrence should be anticipated.

Topics: Child; Disease Progression; Female; Glomerulosclerosis, Focal Segmental; Humans; Intracellular Signaling Peptides and Proteins; Kidney Failure, Chronic; Kidney Transplantation; Membrane Proteins; Mutation; Recurrence

To investigate the effect of Fushengong Decoction on the expression of nephrin mRNA in renal tissue of rats with chronic renal failure (CRF).. Fifty five male SD rats were randomly divided into five groups: control group, CRF model group, and low, medium and high Fushengong Decoction dose groups. Rats in control group were fed with standard chow, while the other four groups were fed with adenine to make CRF. The rats in control group received intra-gastric normal saline (NS) of 20 mL/(kg · d) for 30 d, while those in low, medium and high Fushengong Decoction dose groups received Fushengong Decoction at the dose of 4 g/kg, 8 g/kg and 16 g/kg respectively, once a day for 30 d. After that, 24 h urinary protein in urine was measured, blood urea nitrogen (BUN) and serum creatinine (SCr) were detected. Histomorphology of glomerulus were studied by HE staining, and the expression of nephrin were detected by immunohistochemistry and RT-PCR.. Compared to the control group, the levels of 24 h urinary protein, BUN and SCr increased significantly (P < 0.05) and the expression of nephrin protein and mRNA decreased significantly (P < 0.05) in CRF model group. The renal interstitium showed fibrotic lesions in model group. The levels of 24 h urinary protein, BUN and SCr decreased significantly after the treatment of Fushengong Decoction (P < 0.05), while the expression of nephrin protein and mRNA increased significantly (P < 0.05).. Fushengong Decoction could reduce urinary protein and relieve renal damage in rats with CRF by improving the expression of nephrin and reducing the injury of podocytes.

Topics: Animals; Blood Urea Nitrogen; Creatinine; Drugs, Chinese Herbal; Kidney; Kidney Failure, Chronic; Male; Membrane Proteins; Random Allocation; Rats; Rats, Sprague-Dawley; RNA, Messenger

Nephrotic syndrome (NS), the association of gross proteinuria, hypoalbuminaemia, edema, and hyperlipidemia, can be clinically divided into steroid-sensitive (SSNS) and steroid-resistant (SRNS) forms. SRNS regularly progresses to end-stage renal failure. By homozygosity mapping and whole exome sequencing, we here identify recessive mutations in Crumbs homolog 2 (CRB2) in four different families affected by SRNS. Previously, we established a requirement for zebrafish crb2b, a conserved regulator of epithelial polarity, in podocyte morphogenesis. By characterization of a loss-of-function mutation in zebrafish crb2b, we now show that zebrafish crb2b is required for podocyte foot process arborization, slit diaphragm formation, and proper nephrin trafficking. Furthermore, by complementation experiments in zebrafish, we demonstrate that CRB2 mutations result in loss of function and therefore constitute causative mutations leading to NS in humans. These results implicate defects in podocyte apico-basal polarity in the pathogenesis of NS.

Topics: Amino Acid Sequence; Animals; Carrier Proteins; Child; Child, Preschool; Chromosome Mapping; Exome; Genes, Recessive; Homozygote; Humans; Infant; Kidney Failure, Chronic; Membrane Proteins; Molecular Sequence Data; Mutation; Nephrotic Syndrome; Podocytes; Rats; Zebrafish

Presumed genetic risk for diabetic and nondiabetic end stage renal disease is strong in African Americans.. Exome sequencing data from African Americans with type 2 diabetic end stage renal disease and nondiabetic, non-nephropathy controls in the T2D-GENES study (Discovery, n=529 patients and n=535 controls) were evaluated, focusing on missense variants in NPHS1. Associated variants were then evaluated in independent type 2 diabetic end stage renal disease (Replication, n=1305 patients and n=760 controls), nondiabetic end stage renal disease (n=1705), and type 2 diabetes-only, non-nephropathy samples (n=503). All participants were recruited from dialysis facilities and internal medicine clinics across the southeastern United States from 1991 to present. Additional NPHS1 missense variants were identified from exome sequencing resources, genotyped, and sequence kernel association testing was then performed.. Initial analysis identified rs35238405 (T233A; minor allele frequency=0.0096) as associated with type 2 diabetic end stage renal disease (adjustment for admixture P=0.042; adjustment for admixture+APOL1 P=0.080; odds ratio, 2.89 and 2.36, respectively); with replication in independent type 2 diabetic end stage renal disease samples (P=0.018; odds ratio, 4.30) and nondiabetic end stage renal disease samples (P=0.016; odds ratio, 4.48). In a combined analysis (all patients with end stage renal disease versus all controls), T233A was associated with all-cause end stage renal disease (P=0.0038; odds ratio, 2.82; n=3270 patients and n=1187 controls). A P-value of <0.001 was obtained after adjustment for admixture and APOL1 in sequence kernel association testing. Two additional variants (H800R and Y1174H) were nominally associated with protection from end stage renal disease (P=0.036; odds ratio, 0.44; P=0.0084; odds ratio, 0.040, respectively) in the locus-wide single-variant association tests.. Coding variants in NPHS1 are associated with both risk for and protection from common forms of nephropathy in African Americans.

Topics: Aged; Apolipoprotein L1; Apolipoproteins; Black or African American; Case-Control Studies; Diabetes Mellitus, Type 2; Diabetic Nephropathies; Female; Gene Frequency; Genetic Predisposition to Disease; Humans; Kidney Failure, Chronic; Lipoproteins, HDL; Male; Membrane Proteins; Middle Aged; Odds Ratio; Phenotype; Polymorphism, Single Nucleotide; Protective Factors; Risk Assessment; Risk Factors

Although hyperhomocysteinemia (hHcys) has been recognized as an important independent risk factor in the progression of end-stage renal disease and in the development of cardiovascular complications related to end-stage renal disease, the mechanisms triggering the pathogenic actions of hHcys are not yet fully understood. The present study was designed to investigate the contribution of nucleotide-binding oligomerization domain containing 2 (NOD2), an intracellular innate immunity mediator, to the development of glomerulosclerosis in hHcys. Our results showed that NOD2 deficiency ameliorated renal injury in mice with hHcys. We further discovered the novel role of NOD2 in mediating Ca(2+) signaling and found that homocysteine-induced NOD2 expression enhanced transient receptor potential cation channel 6 (TRPC6) expression and TRPC6-mediated calcium influx and currents, leading to intracellular Ca(2+) release, ultimately resulting in podocyte cytoskeleton rearrangement and apoptosis. Moreover, we found that nephrin expression was downregulated dependently by NOD2, and overexpression of nephrin attenuated homocysteine-induced TRPC6 expression in podocytes. The results add evidence to support the essential role of nephrin in mediating NOD2-induced TRPC6 expression in hHcys. In conclusion, our results for the first time establish a previously unknown function of NOD2 for the regulation of TRPC6 channels, suggesting that TRPC6-dependent Ca(2+) signaling is one of the critical signal transduction pathways that links innate immunity mediator NOD2 to podocyte injury. Pharmacological targeting of NOD2 signaling pathways at multiple levels may help design a new approach to develop therapeutic strategies for treatment of hHcys-associated end-stage renal disease.

Topics: Animals; Calcium Signaling; Cytoskeleton; Hyperhomocysteinemia; Kidney Failure, Chronic; Male; Membrane Proteins; Mice; Mice, Knockout; Nod2 Signaling Adaptor Protein; Podocytes; TRPC Cation Channels; TRPC6 Cation Channel

Infants with congenital nephrotic syndrome (CNS) develop severe nephrotic syndrome that is resistant to medical therapy, and bilateral nephrectomy is recommended toward the end of the first year of life followed by renal replacement therapy. CNS infants in New Zealand have been observed to exhibit a different course to those with the typical Finnish mutation.. A database of CNS children at our center was retrospectively examined. All cases diagnosed between 1975 and 2011 were reviewed. Demographic data, clinical features, genetic mutations, treatment, and outcome were extracted from clinical records.. Thirty-five patients with CNS, 23 children of Maori descent, and 12 Caucasians . Fourteen had died of either bacterial sepsis or intracranial thrombosis. Maori children had displayed a highly variable and protracted timeline to end-stage renal disease (ESRD) with median renal survival of 30 years versus 0.7 years in Caucasian patients. Mutation analysis of NPHS1 showed a founder mutation in the Maori population.. Congenital nephrotic syndrome in New Zealand Maori children exhibit a different clinical course to Caucasian children and have a mutation that was first described in this ethnic group.

Topics: Adolescent; Adult; Child; Child, Preschool; Disease Progression; Female; Founder Effect; Genetic Predisposition to Disease; Humans; Infant; Infant, Newborn; Kidney Failure, Chronic; Male; Membrane Proteins; Mutation; Native Hawaiian or Other Pacific Islander; Nephrotic Syndrome; New Zealand; Phenotype; Prognosis; Renal Replacement Therapy; Retrospective Studies; Risk Factors; Time Factors; White People; Young Adult

Topics: Burkitt Lymphoma; Chromosomes, Human, Pair 19; Consanguinity; Exons; Fatal Outcome; Genotype; Humans; Infant; Iran; Kidney Failure, Chronic; Kidney Transplantation; Male; Membrane Proteins; Nephrotic Syndrome; Phenotype; RNA Splice Sites; RNA Splicing; Sequence Analysis, DNA

Podocyte depletion is a major mechanism driving glomerulosclerosis. Progression is the process by which progressive glomerulosclerosis leads to end stage kidney disease (ESKD). In order to determine mechanisms contributing to persistent podocyte loss, we used a human diphtheria toxin transgenic rat model. After initial diphtheria toxin-induced podocyte injury (over 30% loss in 4 weeks), glomeruli became destabilized, resulting in continued autonomous podocyte loss causing global podocyte depletion (ESKD) by 13 weeks. This was monitored by urine mRNA analysis and by quantitating podocytes in glomeruli. Similar patterns of podocyte depletion were found in the puromycin aminonucleoside and 5/6 nephrectomy rat models of progressive end-stage disease. Angiotensin II blockade (combined enalapril and losartan) restabilized the glomeruli, and prevented continuous podocyte loss and progression to ESKD. Discontinuing angiotensin II blockade resulted in recurrent glomerular destabilization, podocyte loss, and progression to ESKD. Reduction in blood pressure alone did not reduce proteinuria or prevent podocyte loss from destabilized glomeruli. The protective effect of angiotensin II blockade was entirely accounted for by reduced podocyte loss. Thus, an initiating event resulting in a critical degree of podocyte depletion can destabilize glomeruli and initiate a superimposed angiotensin II-dependent podocyte loss process that accelerates progression resulting in eventual global podocyte depletion and ESKD. These events can be monitored noninvasively in real-time through urine mRNA assays.

Topics: Angiotensin II; Animals; Antihypertensive Agents; Disease Models, Animal; Humans; Intracellular Signaling Peptides and Proteins; Kidney Failure, Chronic; Kidney Glomerulus; Male; Membrane Proteins; Podocytes; Rats; Rats, Inbred F344; Rats, Sprague-Dawley; Rats, Transgenic; RNA, Messenger

The number of the chronic renal failure (CRF) patients is increasing explosively. Hypertension, proteinuria, inflammation, fibrosis, and oxidative stress are intertwined in a complicated manner that leads to the progression of CRF. However, the therapeutic strategies to delay its progression are limited. Since serine proteases are involved in many processes that contribute to these risk factors, we investigated the effects of a synthetic serine protease inhibitor, camostat mesilate (CM), on the progression of CRF in 5/6 nephrectomized (Nx) rats. Eighteen male Sprague-Dawley rats were divided into three groups: a sham-operated group (n = 6), a vehicle-treated Nx group (n = 6), and a CM-treated Nx group (n = 6). Following the 9-wk study period, both proteinuria and serum creatinine levels were substantially increased in the vehicle-treated Nx group, and treatment with CM significantly reduced proteinuria and serum creatinine levels. The levels of podocyte-associated proteins in glomeruli, such as nephrin and synaptopodin, were markedly decreased by 5/6 nephrectomy, and this was significantly ameliorated by CM. CM also suppressed the levels of inflammatory and fibrotic marker mRNAs including transforming growth factor-β1, TNF-α, collagen types I, III, and IV, and reduced glomerulosclerosis, glomerular hypertrophy, and interstitial fibrosis in histological studies. Furthermore, CM decreased the expression of NADPH oxidase component mRNAs, as well as reactive oxygen species generation and advanced oxidative protein product levels. Our present results strongly suggest the possibility that CM could be a useful therapeutic agent against the progression of CRF.

Topics: Animals; Creatinine; Disease Progression; Esters; Gabexate; Guanidines; Kidney; Kidney Failure, Chronic; Male; Membrane Proteins; Microfilament Proteins; Nephrectomy; Oxidative Stress; Proteinuria; Rats; Rats, Sprague-Dawley; Serine Proteinase Inhibitors; Treatment Outcome

The MYH9 gene encodes a non-muscle myosin IIA heavy chain (NMMHC-IIA) expressed in podocytes. Heterozygous MYH9 mutations cause a set of overlapping syndromes characterized by variable degrees of deafness, morphologic abnormalities of platelets and focal segmental glomerulosclerosis (FSGS) with progressive renal dysfunction. Similar glomerular lesions are seen in a variety of nephropathies, including an idiopathic form of FSGS in children which recurs in renal allografts, implying a circulating factor that affects glomerular podocyte biology. It is unknown whether NMMHC-IIA is perturbed in the idiopathic form of FSGS. We describe a pediatric patient with typical idiopathic FSGS, in whom proteinuria recurred within hours of deceased donor renal transplantation but who responded to plasmapheresis. We demonstrate in vitro that plasmapheresis effluent from our patient rapidly decreased cultured podocyte levels of the phosphorylated myosin light chain (MLC) that mediates NMMHC-IIA binding to actin and induced dispersion of NMMHC-IIA from its usual position along actin stress fibers. FSGS plasma also caused dispersion of slit diaphragm proteins (nephrin and podocin) and vinculin-positive focal adhesion complexes. Our observations suggest that the putative circulating factor in idiopathic FSGS disrupts normal NMMHC-IIA function in podocytes and might contribute to the pathogenesis of recurrent FSGS in other children.

Topics: Adolescent; Apoptosis; Cell Line; Cell Size; Child; Female; Glomerulosclerosis, Focal Segmental; Humans; Intracellular Signaling Peptides and Proteins; Kidney Failure, Chronic; Kidney Transplantation; Membrane Proteins; Molecular Motor Proteins; Myosin Heavy Chains; Myosin Light Chains; Phosphorylation; Plasmapheresis; Podocytes; Protein Transport; Proteinuria; Recurrence; Stress Fibers; Time Factors; Treatment Outcome

Podocytes cover the glomerulus and their adjacent foot processes form a principal barrier called the slit diaphragm. Podocyte dysfunctions, including podocyte loss and slit diaphragm disruptions, induce chronic kidney diseases (CKD). In this study, we analyzed the correlations between podocyte injuries and renal dysfunctions in domestic carnivores. Dogs and cats were divided into normal and CKD groups according to renal histopathology and plasma creatinine values. Immunostaining results showed that linear reactions of slit diaphragm molecules, e.g., nephrin, podocin, and ACTN4, were parallel to glomerular capillaries in all animals. However, in dogs, reactions of nephrin and ACTN4 were changed to a granular pattern in the CKD group, and their intensities significantly decreased with the number of podocytes in the glomerulus. Moreover, the expression of nephrin and ACTN4 negatively correlated with creatinine. Real-time PCR analysis showed that nephrin mRNA expression in the kidneys of CKD dogs was significantly lower than that in normal animals, and negatively correlated with creatinine. Although no significant correlation between renal dysfunction and podocyte injury was detected in cats, histoplanimetric scores of tubulointerstitial lesions in CKD cats were higher than those in both normal cats and diseased dogs. Furthermore, mRNAs of WT1 and SD molecules were detected in urine from CKD animals. In conclusion, podocyte injuries such as podocytopenia and decreased expression of nephrin and ACTN4 in the glomerulus were more strongly correlated with renal dysfunction in dogs than in cats. These findings suggest that the CKD pathogenesis, especially susceptibilities to podocyte injuries, differed between dogs and cats.

Topics: Animals; Cats; Dogs; Immunohistochemistry; Intracellular Signaling Peptides and Proteins; Kidney Failure, Chronic; Kidney Function Tests; Membrane Proteins; Microscopy, Electron, Transmission; Podocytes; Real-Time Polymerase Chain Reaction; Reverse Transcriptase Polymerase Chain Reaction

Mutations in NPHS1, which encodes nephrin, are the main causes of congenital nephrotic syndrome (CNS) in Finnish patients, whereas mutations in NPHS2, which encodes podocin, are typically responsible for childhood-onset steroid-resistant nephrotic syndrome in European populations. Genotype-phenotype correlations are not well understood in non-Finnish patients. We evaluated the clinical presentation, kidney histology, and disease progression in non-Finnish CNS cases by mutational screening in 107 families (117 cases) by sequencing the entire coding regions of NPHS1, NPHS2, PLCE1, WT1, LAMB2, PDSS2, COQ2, and NEPH1. We found that CNS describes a heterogeneous group of disorders in non-Finnish populations. We identified nephrin and podocin mutations in most families and only rarely found mutations in genes implicated in other hereditary forms of NS. In approximately 20% of cases, we could not identify the underlying genetic cause. Consistent with the major role of nephrin at the slit diaphragm, NPHS1 mutations associated with an earlier onset of disease and worse renal outcomes than NPHS2 mutations. Milder cases resulting from mutant NPHS1 had either two mutations in the cytoplasmic tail or two missense mutations in the extracellular domain, including at least one that preserved structure and function. In addition, we extend the spectrum of known NPHS1 mutations by describing long NPHS1 deletions. In summary, these data demonstrate that CNS is not a distinct clinical entity in non-Finnish populations but rather a clinically and genetically heterogeneous group of disorders.

Topics: Africa, Northern; Biopsy; Child, Preschool; Cohort Studies; Disease Progression; Europe; Female; Genetic Testing; Genotype; Humans; Infant; Infant, Newborn; Intracellular Signaling Peptides and Proteins; Kaplan-Meier Estimate; Kidney; Kidney Failure, Chronic; Male; Membrane Proteins; Mutation; Nephrotic Syndrome; Phenotype; Retrospective Studies; Turkey

Mutations in podocyte genes are associated with steroid-resistant nephrotic syndrome (SRNS), mostly affecting younger age groups. To date, it is unclear whether these patients benefit from intensified immunosuppression with cyclosporine A (CsA). The aim of this study was to evaluate the influence of podocyte gene defects in congenital nephrotic syndrome (CNS) and pediatric SRNS on the efficacy of CsA therapy and preservation of renal function.. Genotyping was performed in 91 CNS/SRNS patients, irrespective of age at manifestation or response to CsA.. Mutations were identified in 52% of families (11 NPHS1, 17 NPHS2, 11 WT1, 1 LAMB2, 3 TRPC6). Sixty-eight percent of patients with nongenetic SRNS responded to CsA, most of them achieved complete remission. In contrast, none of the patients with genetic CNS/SRNS experienced a complete remission and only two (17%) achieved a partial response, both affected by a WT1 mutation. Preservation of renal function was significantly better in children with nongenetic disease after a mean follow-up time of 8.6 years (ESRD in 29% versus 71%).. The mutation detection rate in our population was high (52%). Most patients with genetic CNS/SRNS did not benefit from CsA with significantly lower response rates compared with nongenetic patients and showed rapid progression to end-stage renal failure. These data strongly support the idea not to expose CNS/SRNS patients with inherited defects related to podocyte function to intensified immunosuppression with CsA.

Topics: Adolescent; Child; Child, Preschool; Cyclosporine; Disease Progression; DNA Mutational Analysis; Drug Resistance; Female; Genes, Wilms Tumor; Genetic Predisposition to Disease; Germany; Heredity; Hospitals, Pediatric; Hospitals, University; Humans; Immunosuppressive Agents; Infant; Intracellular Signaling Peptides and Proteins; Kaplan-Meier Estimate; Kidney; Kidney Failure, Chronic; Laminin; Male; Membrane Proteins; Mutation; Nephrotic Syndrome; Patient Selection; Phenotype; Retrospective Studies; Steroids; Time Factors; Treatment Outcome; TRPC Cation Channels; TRPC6 Cation Channel

Elevated level of homocysteine (Hcy), known as hyperhomocysteinemia (HHcy), is associated with end-stage renal diseases. Hcy metabolizes in the body to produce hydrogen sulfide (H(2)S), and studies have demonstrated a protective role of H(2)S in end-stage organ failure. However, the role of H(2)S in HHcy-associated renal diseases is unclear. The present study was aimed to determine the role of H(2)S in HHcy-associated renal damage. Cystathionine-beta-synthase heterozygous (CBS+/-) and wild-type (WT, C57BL/6J) mice with two kidney (2-K) were used in this study and supplemented with or without NaHS (30 micromol/l, H(2)S donor) in the drinking water. To expedite the HHcy-associated glomerular damage, uninephrectomized (1-K) CBS(+/-) and 1-K WT mice were also used with or without NaHS supplementation. Plasma Hcy levels were elevated in CBS(+/-) 2-K and 1-K and WT 1-K mice along with increased proteinuria, whereas, plasma levels of H(2)S were attenuated in these groups compared with WT 2-K mice. Interestingly, H(2)S supplementation increased plasma H(2)S level and normalized the urinary protein secretion in the similar groups of animals as above. Increased activity of matrix metalloproteinase (MMP)-2 and -9 and apoptotic cells were observed in the renal cortical tissues of CBS(+/-) 2-K and 1-K and WT 1-K mice; however, H(2)S prevented apoptotic cell death and normalized increased MMP activities. Increased expression of desmin and downregulation of nephrin in the cortical tissue of CBS(+/-) 2-K and 1-K and WT 1-K mice were ameliorated with H(2)S supplementation. Additionally, in the kidney tissues of CBS(+/-) 2-K and 1-K and WT 1-K mice, increased superoxide (O(2)(*-)) production and reduced glutathione (GSH)-to-oxidized glutathione (GSSG) ratio were normalized with exogenous H(2)S supplementation. These results demonstrate that HHcy-associated renal damage is related to decreased endogenous H(2)S generation in the body. Additionally, here we demonstrate with evidence that H(2)S supplementation prevents HHcy-associated renal damage, in part, through its antioxidant properties.

Topics: Animals; Antioxidants; Apoptosis; Cystathionine beta-Synthase; Desmin; Disease Models, Animal; Glutathione; Glutathione Disulfide; Homocysteine; Hydrogen Sulfide; Hyperhomocysteinemia; Kidney; Kidney Failure, Chronic; Male; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Membrane Proteins; Mice; Mice, Inbred C57BL; Mice, Knockout; Nephrectomy; Oxidative Stress; Proteinuria; Sulfides; Superoxides

The leading causes of albuminuria and end-stage renal failure are secondary to abnormalities in the production or cellular action of insulin, including diabetes and hyperinsulinemic metabolic syndrome. The human glomerular podocyte is a critical cell for maintaining the filtration barrier of the kidney and preventing albuminuria. We have recently shown this cell to be insulin sensitive with respect to glucose uptake, with kinetics similar to muscle cells. We now show that the podocyte protein nephrin is essential for this process. Conditionally immortalized podocytes from two different patients with nephrin mutations (natural human nephrin mutant models) were unresponsive to insulin. Knocking nephrin down with siRNA in wild-type podocytes abrogated the insulin response, and stable nephrin transfection of nephrin-deficient podocytes rescued their insulin response. Mechanistically, we show that nephrin allows the GLUT1- and GLUT4-rich vesicles to fuse with the membrane of this cell. Furthermore, we show that the COOH of nephrin interacts with the vesicular SNARE protein VAMP2 in vitro and ex vivo (using yeast-2 hybrid and coimmunoprecipitation studies). This work demonstrates a previously unsuspected role of nephrin in vesicular docking and insulin responsiveness of podocytes.

Topics: Biological Transport; Child; Deoxyglucose; Humans; Kidney Failure, Chronic; Kidney Glomerulus; Membrane Proteins; Nephrotic Syndrome; Podocytes; RNA, Small Interfering; Vesicle-Associated Membrane Protein 2

Pax2 is a transcription factor with important functions during kidney development . Ectopic expression of Pax2 in podocytes has been reported in various glomerular diseases , but the functional relevance remains unknown. We developed an inducible mouse model that allows activation of Pax2 specifically in podocytes. Persistent expression of Pax2 did not interfere with the initial differentiation of podocytes, but mice ectopically expressing PAX2 developed end-stage renal failure soon after birth. Similarly, activation of PAX2 in healthy adult animals resulted in renal disease within 3 weeks after podocyte-specific induction of a deleter Cre. PAX2 activation caused repression of the podocyte key regulator molecule Wt1 and consequently a dramatic reduction of nephrin expression. Recruitment of the groucho-related protein TLE4 may be involved in converting Pax2 into a transcriptional repressor of Wt1. Finally, treatment of mice with an angiotensin-converting enzyme (ACE) inhibitor normalized renal function and induced upregulation of the important structural molecule nephrin via a Wt1-independent pathway. Our data demonstrate the functional significance of PAX2 reexpression in mature podocytes for the development of glomerular diseases and suggest that reactivation of PAX genes in terminally differentiated cells leads to a more dedifferentiated phenotype.

Topics: Angiotensin-Converting Enzyme Inhibitors; Animals; Disease Models, Animal; Enalapril; Gene Expression Regulation; Kidney Failure, Chronic; Male; Membrane Proteins; Mice; PAX2 Transcription Factor; Podocytes; Proteinuria; WT1 Proteins

The identification of the underlying gene defect in some cases of steroid resistant nephrotic syndrome (SRNS) has recently led to a critical breakthrough in the understanding of the pathogenesis of nephrotic syndromes. The more severe form of hereditary nephrotic syndromes is the congenital nephrotic syndrome of the Finnish type (CNF). The causative gene, NPHS1, encodes a novel protein, nephrin which is a transmembrane protein belonging to the immunoglobulin superfamily specifically expressed in the podocyte at the slit diaphragm. Using a positional cloning approach, our group identified a gene, NPHS2, involved in a specific entity of familial SRNS characterized by early onset, complete steroid-resistance, rapid progression to ESRD and no recurrence after renal transplantation. NPHS2 encodes a novel membrane protein named podocin localized at the cytoplasmic part of the slit diaphragm. Familial autosomal dominant cases of primary FSGS have been described in adulthood. Two corresponding genes have been mapped to date, one to 19q13 and the second to 11q21-22. The former has been identified as ACTN4, the gene encoding the actin-binding protein, a-actinin 4. Other genes involved in the slit-diaphragm or the nephrotic syndrome are CD2-associated protein (CD2AP), FAT1, WT1, LMX1B, SMARCAL1. Altogether, these data demonstrate the pivotal role of the podocyte in the development and the maintenance of the glomerular filtration barrier and the crucial role of the genetic factors in the development of SRNS.

Topics: Actinin; Adaptor Proteins, Signal Transducing; Adult; Child; Cytoskeletal Proteins; Disease Progression; Drug Resistance; Humans; Intracellular Signaling Peptides and Proteins; Kidney Failure, Chronic; Kidney Transplantation; Membrane Proteins; Microfilament Proteins; Mutation; Nephrotic Syndrome; Proteins; Steroids

Recent progress in defining the genetic basis of inherited glomerular diseases has provided a completely new understanding of the glomerular filter of the kidney and has helped illuminate the pathogenesis of acquired and inherited renal proteinuric diseases. Based on the findings of molecular genetics in nephrology we will discuss the current understanding of the glomerular filter and provide an idea how genetic testing in the future may help to guide therapy in patients suffering from nephrotic syndrome and progressive renal failure.

Topics: Adult; Animals; Child; Finland; Genetic Predisposition to Disease; Glomerular Filtration Rate; Glomerulosclerosis, Focal Segmental; Humans; Infant, Newborn; Kidney Diseases; Kidney Failure, Chronic; Kidney Glomerulus; Membrane Proteins; Mice; Mutation; Nephrotic Syndrome; Proteins; Proteinuria