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Minimal change disease (MCD) is a universal primary glomerular disease contributing to nephrotic syndrome. Lon peptidase 1 (LONP1) has been suggested to protect podocytes from damage during the progression of MCD. Accordingly, our research further explored the specific mechanisms of LONP1. Initially, the expressions of TRPC6, p-ERK1/2, and LONP1 in the kidney tissues of MCD patients were detected by immunohistochemistry and Western blot. Human podocytes AB8/13 were serially subjected to transfection with shTRPC6/shNC, and 48-h treatment with 30 µg/ml puromycin aminonucleoside (PAN). The viability, apoptosis, and migration of AB8/13 cells were assessed by cell counting kit-8, flow cytometry, and transwell assays. The mRNA and protein expressions of LONP1 were downregulated while those of TRPC6 were upregulated in the kidney tissues of MCD patients. PAN induced podocyte injury and migration and inhibited LONP1 expression, whereas TRPC6 silencing did oppositely. The phosphorylation level of ERK1/2 was reduced in MCD samples, which was negatively associated with TRPC6 expression and positively associated with LONP1 expression. Furthermore, ERK phosphorylation agonist offset the effects of TRPC6 silencing on mitigating podocyte injury and migration as well as upregulating LONP1 expression. Collectively, TRPC6 knockdown-induced ERK1/2 inactivation can ameliorate podocyte injury in MCD by increasing the expression of LONP1.

Objectives: The small GTPase Rac1 (RAC1) has been linked to podocyte disorders and steroid-sensitive nephrotic syndrome (SSNS). The aim of this study was to explore and validate the potential causal association between circulating RAC1 and SSNS., Methods: The association between circulating RAC1 and SSNS at both gene expression and proteomic levels was investigated using Mendelian randomization analysis, and further validated by single-cell RNA-sequencing, proteomic analysis, and experimental studies. The genetic instruments comprised cis-expression quantitative trait loci (cis-eQTLs) associated with RAC1 gene expression and protein QTLs correlated with plasma RAC1 protein levels. Causal associations were estimated utilizing the inverse variance weighted and MR-PRESSO methods. Validation of RAC1 expression was conducted through single-cell RNA-sequencing of peripheral blood mononuclear cells from patients with SSNS and healthy controls. Proteomic analysis was performed among patients with minimal change nephrotic syndrome. Experimental validation was conducted using a puromycin aminonucleoside (PAN)-induced nephrosis model., Results: Increased expression of RAC1 was associated with a higher risk of SSNS (gene expression level: odds ratio [OR], 1.53; 95% confidence interval [CI], 1.02-2.28; protein level: OR, 1.82; 95% CI, 1.05-3.17). The results of MR-PRESSO were consistent (gene expression level: OR, 1.49; 95% CI, 1.17-1.92; protein level: OR, 1.81; 95% CI, 1.16-2.85). Single-cell RNA sequencing and proteomic analysis confirmed elevated RAC1 expression in patients with SSNS compared to healthy controls. Experimental data further supported increased RAC1 expression in PAN-induced nephropathy., Conclusions: Increased expression of RAC1 might be causally associated with SSNS, suggesting that targeting RAC1 might represent a potential therapeutic strategy for SSNS.

Minimal Change Disease (MCD) is a predominant cause of idiopathic nephrotic syndrome in the pediatric population, yet presents significant clinical challenges due to its frequent relapses and steroid resistance. Despite its relatively benign histological appearance, MCD is characterized by severe proteinuria, hypoalbuminemia, and edema, which may affect patient outcomes. Current treatment strategies primarily rely on corticosteroids, which are effective in inducing remission but are associated with high relapse rates, steroid resistance, and numerous long-term side effects, underscoring the need for more targeted and effective therapeutic approaches. This narrative review synthesizes current knowledge on the pathophysiological mechanisms underlying MCD, focusing on the following three critical areas: podocyte dysfunction, immune dysregulation, and genetic susceptibility. Podocyte dysfunction, particularly involving alterations in nephrin, plays a central role in the breakdown of the glomerular filtration barrier, leading to the characteristic proteinuria observed in MCD. Immune dysregulation, including the presence of autoantibodies against nephrin and other podocyte components, exacerbates podocyte injury and contributes to disease progression, suggesting an autoimmune component to the disease. Genetic factors, particularly mutations in the NPHS1 and NPHS2 genes, have been identified as significant contributors to disease susceptibility, influencing the variability in treatment response and overall disease severity. Understanding these mechanisms is crucial for developing targeted therapies that address the underlying causes of MCD rather than merely managing its symptoms. This review highlights the need for further research into these pathophysiological processes to pave the way for more personalized and effective treatment strategies, ultimately improving patient outcomes and reducing reliance on corticosteroids.

Background: Idiop athic nephrotic syndrome (INS) is classified in children according to response to initial corticosteroid therapy into steroid-sensitive (SSNS) and steroid-resistant nephrotic syndrome (SRNS), and in adults according to histology into minimal change disease (MCD) and focal segmental glomerulosclerosis (FSGS). However, there is well-recognised phenotypic overlap between these entities. Genome-wide association studies (GWAS) have shown a strong association between SSNS and variation at HLA, suggesting an underlying immunological basis. We sought to determine whether a risk score generated from genetic variants associated with SSNS could be used to gain insight into the pathophysiology of INS presenting in other ways., Methods: We developed an SSNS genetic risk score (SSNS-GRS) from the five variants independently associated with childhood SSNS in a previous European GWAS. We quantified SSNS-GRS in independent cohorts of European individuals with childhood SSNS, non-monogenic SRNS, MCD, and FSGS, and contrasted them with SSNS-GRS quantified in individuals with monogenic SRNS, membranous nephropathy (a different immune-mediated disease-causing nephrotic syndrome), and healthy controls., Results: The SSNS-GRS was significantly elevated in cohorts with SSNS, non-monogenic SRNS, MCD, and FSGS compared to healthy participants and those with membranous nephropathy. The SSNS-GRS in all cohorts with non-monogenic INS were also significantly elevated compared to those with monogenic SRNS., Conclusions: The shared genetic risk factors among patients with different presentations of INS strongly suggests a shared autoimmune pathogenesis when monogenic causes are excluded. Use of the SSNS-GRS, in addition to testing for monogenic causes, may help to classify patients presenting with INS. A higher resolution version of the Graphical abstract is available as Supplementary information., (© 2022. The Author(s).)

Herein, we report that Shroom3 knockdown, via Fyn inhibition, induced albuminuria with foot process effacement (FPE) without focal segmental glomerulosclerosis (FSGS) or podocytopenia. Interestingly, knockdown mice had reduced podocyte volumes. Human minimal change disease (MCD), where podocyte Fyn inactivation was reported, also showed lower glomerular volumes than FSGS. We hypothesized that lower glomerular volume prevented the progression to podocytopenia. To test this hypothesis, we utilized unilateral and 5/6th nephrectomy models in Shroom3-KD mice. Knockdown mice exhibited less glomerular and podocyte hypertrophy after nephrectomy. FYN-knockdown podocytes had similar reductions in podocyte volume, implying that Fyn was downstream of Shroom3. Using SHROOM3 or FYN knockdown, we confirmed reduced podocyte protein content, along with significantly increased phosphorylated AMPK, a negative regulator of anabolism. AMPK activation resulted from increased cytoplasmic redistribution of LKB1 in podocytes. Inhibition of AMPK abolished the reduction in glomerular volume and induced podocytopenia in mice with FPE, suggesting a protective role for AMPK activation. In agreement with this, treatment of glomerular injury models with AMPK activators restricted glomerular volume, podocytopenia, and progression to FSGS. Glomerular transcriptomes from MCD biopsies also showed significant enrichment of Fyn inactivation and Ampk activation versus FSGS glomeruli. In summary, we demonstrated the important role of AMPK in glomerular volume regulation and podocyte survival. Our data suggest that AMPK activation adaptively regulates glomerular volume to prevent podocytopenia in the context of podocyte injury.

The discovery of microRNAs (miRNAs) has opened up new avenues of research to understand the molecular basis of a number of diseases. Because of their conservative feature in evolution and important role in the physiological function, microRNAs could be treated as predictors for disease classification and clinical process based on the specific expression. The identification of novel miRNAs and their target genes can be considered as potential targets for novel drugs. Furthermore, currently, the circulatory and urinary exosomal miRNAs are gaining increasing attention as their expression profiles are often associated with specific diseases, and they exhibit great potential as noninvasive or minimally invasive biomarkers for the diagnosis of various diseases. The remarkable stability of these extracellular miRNAs circulating in the blood or excreted in the urine underscored their key importance as biomarkers of certain diseases. There is voluminous literature concerning the role of microRNAs in other diseases, such as cardiovascular diseases, diabetic nephropathy, and so forth. However, little is known about their diagnostic ability for the pediatric nephrotic syndrome (NS). The present review article highlights the recent advances in the role of miRNAs in the pathogenesis and molecular basis of NS with an aim to bring new insights into further research applications for the development of new therapeutic agents for NS., (© 2021 Wiley Periodicals LLC.)

Kidney injury is a well-known complication in people with coronavirus disease 2019 (COVID-19). In kidney transplant recipients with COVID-19, presentation with nephrotic syndrome has not been well described. We report on a 49-year-old black female kidney transplant recipient who presented 25 years after transplant with clinical features of nephrotic syndrome following a diagnosis of COVID-19. Histologic examination showed acute tubular injury with unremarkable glomeruli on light microscopy and diffuse foot process effacement of podocytes on electron microscopy, consistent with minimal change-like podocyte injury. Apolipoprotein L1 (APOL1) genetic testing confirmed 2 high-risk APOL1 alleles in the kidney donor. We speculate that COVID-19-induced systemic or local cytokine release could serve as a second hit in the presence of APOL1 risk alleles and mediate a podocytopathy manifesting as nephrotic syndrome. The presented case with minimal change-like disease, occurring in the context of the donor high-risk APOL1 genotype, extends the spectrum of clinical manifestations in COVID-19-associated nephropathy., (Copyright © 2020 Elsevier Inc. All rights reserved.)

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., Competing Interests: The authors have declared that no competing interests exist.

Background: Nucleotide-binding oligomerization domain (NOD)-like receptors (NLRs) are intracellular sensors of pathogens and molecules from damaged cells to regulate the inflammatory response in the innate immune system. Emerging evidences suggested a potential role of NLRs in anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). This study aimed to investigate the expression of nucleotide-binding oligomerization domain containing protein 2 (NOD2), NOD-like receptor family pyrin domain containing 3 (NLRP3) and NOD-like receptor family CARD domain containing 5 (NLRC5) in kidneys of AAV patients, and further explored their associations with clinical and pathological parameters., Methods: Thirty-four AAV patients in active stage were recruited. Their renal specimens were processed with immunohistochemistry to assess the expression of three NLRs, and with double immunofluorescence to detect NLRs on intrinsic and infiltrating cells. Analysis of gene expression was also adopted in cultured human podocytes. The associations between expression of NLRs and clinicopathological parameters were analyzed., Results: The expression of NOD2, NLRP3 and NLRC5 was significantly higher in kidneys from AAV patients than those from normal controls, minimal change disease or class IV lupus nephritis. These NLRs co-localized with podocytes and infiltrating inflammatory cells. The mean optical density of NOD2 in glomeruli was significantly higher in crescentic class than non-crescentic class, and correlated with levels of proteinuria and serum creatinine at renal biopsy. The mean optical density of NLRC5 in glomeruli was significantly higher in crescentic class than non-crescentic class, and correlated with proteinuria level, Birmingham Vasculitis Activity Score and the proportion of crescents in the renal specimen., Conclusions: The expression of three NLRs was upregulated in kidneys of AAV patients. The expression of NOD2 and NLRC5 was associated with the severity of renal lesions in AAV.

Background: Cell adhesion molecules have been documented to be elevated in numerous immune inflammatory diseases. Minimal change disease (MCD) is an immune disorder. This study aimed to evaluate whether levels of soluble vascular cell adhesion molecule-1 (sVCAM-1) and soluble E-selectin (sE-selectin) reflect disease activity in adult-onset MCD., Methods: A sandwich enzyme-linked immunosorbent assay was used to measure the soluble adhesion molecules in 40 patients with nephrotic-range proteinuria and biopsy-proven MCD, obtained at the time of diagnosis and during remission. Thirty-five age- and sex-matched healthy volunteers served as controls., Results: Patients with MCD during the active stage showed significantly higher levels of sVCAM-1 and sE-selectin when compared to controls. Moreover, sVCAM-1 had significantly positive correlations with both urine protein and serum cholesterol, and was negatively associated with serum albumin. Multiple analyses showed that serum albumin was an independent predictor of sVCAM-1. The correlations between sE-selectin and other clinical parameters were not statistically significant. At follow-up, these markers systematically decreased as the disease went into remission, but the increase in sVCAM-1 persisted even in patients obtaining complete remission for 6 months., Conclusions: Patients with active MCD had increased levels of sVCAM-1 and sE-selectin. The correlation between sVCAM-1 and proteinuria, serum albumin and cholesterol and its decline during remission indicate that sVCAM-1 is associated with disease activity., (Copyright © 2019. Published by Elsevier Inc.)

LXRs, which are nuclear receptors, have 2 isoforms-LXRα and LXRβ. Generally, LXRα is expressed in the liver, kidney, and a limited number of other organs, whereas LXRβ is thought to be expressed ubiquitously. Nevertheless, no clear consensus has been reached on the role of each in kidney lipid metabolism. Many researchers have reported that lipids accumulate in renal tubular epithelial cells during nephrosis. The nephrosis model we used showed the presence of urinary protein 4 days after the induction of illness. Additionally, the model maintained high levels of urinary protein from day 7-14. Lipid accumulation was clearly verified at day 4 and extreme accumulation was observed at day 7. We observed increased expression of LXRα from an early stage of nephrosis. To explore the role of increased LXRα in diseased kidney in vitro, NRK52E, normal kidney tubular epithelial cells, were forced to overexpress LXRα. These cells showed significantly lower lipid accumulation than mock cells did. In contrast, LXRβ knockdown lead to increased lipid accumulation in mock cells, and constancy in overexpressing cells. In normal kidneys, LXRβ is expressed stably to control mainly the intracellular lipids. However, with increasing intracellular lipid accumulation, expression of LXRα and its downstream gene, ABCA1, was upregulated, followed by lipid excretion in an LXRα-dependent manner. This phenomenon strongly suggests the importance of LXRα in lipid metabolism in the diseased kidney., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Planar cell polarity (PCP) pathways control the orientation and alignment of epithelial cells within tissues. Van Gogh-like 2 (Vangl2) is a key PCP protein that is required for the normal differentiation of kidney glomeruli and tubules. Vangl2 has also been implicated in modifying the course of acquired glomerular disease, and here, we further explored how Vangl2 impacts on glomerular pathobiology in this context. Targeted genetic deletion of Vangl2 in mouse glomerular epithelial podocytes enhanced the severity of not only irreversible accelerated nephrotoxic nephritis but also lipopolysaccharide-induced reversible glomerular damage. In each proteinuric model, genetic deletion of Vangl2 in podocytes was associated with an increased ratio of active-MMP9 to inactive MMP9, an enzyme involved in tissue remodelling. In addition, by interrogating microarray data from two cohorts of renal patients, we report increased VANGL2 transcript levels in the glomeruli of individuals with focal segmental glomerulosclerosis, suggesting that the molecule may also be involved in certain human glomerular diseases. These observations support the conclusion that Vangl2 modulates glomerular injury, at least in part by acting as a brake on MMP9, a potentially harmful endogenous enzyme. © 2018 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland., (© 2018 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.)

Background: Treatment of steroid resistant nephrotic syndrome is still a challenge for physicians. There are a growing number of studies exploring genetic background of steroid-resistant glomerulopathies., Case Diagnosis/treatment: We present the case of a 4-year-old girl with steroid-resistant glomerulopathy due to a COQ6 defect with no additional systemic symptoms. The disease did not respond for second-line therapy with calcineurin inhibitor, but it remitted completely after oral treatment with 30 mg/kg/d of coenzyme Q10 (CoQ10). The patient was identified to be a compound heterozygote for two pathogenic variants in COQ6 gene: a known missense substitution c.1078C > T (p.R360W) and a novel frameshift c.804delC mutation. After 12 months of CoQ10 therapy, the child remains in full remission, her physical development accelerated, frequent respiratory airways diseases subsided., Conclusions: Genetic assessment of children with steroid-resistant nephrotic proteinuria enables therapy optimization. Proteinuria caused by a COQ6 gene defect can be successfully treated with CoQ10.

Background: Podocyte injury is the hallmark of proteinuric kidney diseases, such as FSGS and minimal change disease, and destabilization of the podocyte's actin cytoskeleton contributes to podocyte dysfunction in many of these conditions. Although agents, such as glucocorticoids and cyclosporin, stabilize the actin cytoskeleton, systemic toxicity hinders chronic use. We previously showed that loss of the kidney-enriched zinc finger transcription factor Krüppel-like factor 15 (KLF15) increases susceptibility to proteinuric kidney disease and attenuates the salutary effects of retinoic acid and glucocorticoids in the podocyte., Methods: We induced podocyte-specific KLF15 in two proteinuric murine models, HIV-1 transgenic ( Tg26 ) mice and adriamycin (ADR)-induced nephropathy, and used RNA sequencing of isolated glomeruli and subsequent enrichment analysis to investigate pathways mediated by podocyte-specific KLF15 in Tg26 mice. We also explored in cultured human podocytes the potential mediating role of Wilms Tumor 1 (WT1), a transcription factor critical for podocyte differentiation., Results: In Tg26 mice, inducing podocyte-specific KLF15 attenuated podocyte injury, glomerulosclerosis, tubulointerstitial fibrosis, and inflammation, while improving renal function and overall survival; it also attenuated podocyte injury in ADR-treated mice. Enrichment analysis of RNA sequencing from the Tg26 mouse model shows that KLF15 induction activates pathways involved in stabilization of actin cytoskeleton, focal adhesion, and podocyte differentiation. Transcription factor enrichment analysis, with further experimental validation, suggests that KLF15 activity is in part mediated by WT1., Conclusions: Inducing podocyte-specific KLF15 attenuates kidney injury by directly and indirectly upregulating genes critical for podocyte differentiation, suggesting that KLF15 induction might be a potential strategy for treating proteinuric kidney disease., (Copyright © 2018 by the American Society of Nephrology.)

Diabetic nephropathy (DN) is the major cause of end-stage renal failure and is associated with increased morbidity and mortality as compared to other causes of renal disease. Albuminuria is often the first clinical indicator of the presence of DN. However, albuminuria or proteinuria is a common symptom in patients with various renal disorders. Therefore, specific biomarkers for the diagnosis of DN are required. A primary hallmark of DN is the progressive damage and death of glomerular podocytes, resulting in the leaking of proteins into the urine. Urinary exosomes released by podocytes are microvesicles containing information of the originated cells. Podocyte-derived signal transduction factors (PDSTFs) are good candidates to assess podocyte injuries. The profile of PDSTFs in urinary exosomes from patients with DN is different from that from patients with minimal change nehrotic syndrome. In addition, PDSTFs molecules in exosomes were derived from primary murine podocytes under high glucose conditions. Among PDSTFs in urinary exosomes, Wilms tumor 1 (WT1) levels reflected damage of diabetic glomeruli in the patients. Urinary exosomal WT1 can predict the decline in eGFR for the following several years. In conclusion, urinary exosomal WT1 is a useful biomarker to improve risk stratification in patients with DN. J. Med. Invest. 65:208-215, August, 2018.

Background: DNA methylation plays a crucial role in regulating transcription, and changes in DNA methylation affect gene expression and disease development. Minimal change nephrotic syndrome (MCNS) has been reported to involve immunological disturbances. Since the characteristic features of the disease include recurrent relapse and sex and age preference, the disease pathogenesis may be partly related to epigenetic changes. However, little is known about these changes., Methods: We analyzed genome-wide DNA methylation using the microarray-based integrated analysis of methylation by isoschizomers method. This method was used to evaluate methylation in monocytes (patient number; n = 6) and naïve T helper cells (n = 4) from the peripheral blood of MCNS patients both in relapse and following remission and that of healthy controls (n = 5)., Results: In total, 85 co-occurring genes were identified in naïve T helper cells, while 4 such genes were identified in monocytes, which were common among the 3 following comparisons for changes in DNA methylation using sample pairs: (1) relapse versus remission, (2) relapse versus controls, and (3) remission versus controls. In 82 of 85 co-occurring genes (96.5%) in naïve T helper cells, the level of DNA methylation was altered according to disease activity, but was not related to disease activity in the 4 genes detected in monocytes., Conclusions: Therefore, in 82 co-occurring genes in naïve T helper cells, the regulation of DNA methylation was well correlated with the clinical and pathophysiological state. Our genome-wide approach to analyze DNA methylation provides further insight into the pathogenesis of MCNS and indicates potential prediction and diagnostic tool for the disease.

Background: Patients with minimal change nephrotic syndrome (MCNS) often also have allergic diseases. Abnormalities of Th2-derived cytokines and T-cell functions contribute to development of these diseases. On the other hand, imbalances between reactive oxygen species (ROS) and antioxidants have been implicated in MCNS and progression of atopic dermatitis. ROS, produced mainly within mitochondria, subject cells to oxidative stress, while prohibitin 2 protects mitochondria by increasing tolerance to ROS. Additionally, podocin, a member of the slit diaphragm protein complex, contains PHB-like domain that serves as a signaling platform regulating podocyte function through associated transmembrane proteins., Patients and Method: Then, we performed exome sequencing analysis in five patients with frequently relapsing their MCNS associated with allergic disease and serum IgE concentrations of 2000 IU/L or higher., Results: We detected a heterozygous prohibitin 2 polymorphism, c.873-3&#95;873-2 delCA (rs111523336), in 1 patient. This mutation in exon 9 caused frameshifts in regions connected to splicing sites, where they could disrupt transcription of prohibitin 2. Frequency of this polymorphism in exon 9 is 7.3% among Japanese. Increase in peripheral blood ROS even MCNS remission state suggests the heterozygous prohibitin 2 variant may contribute to give more susceptibility towards the recurrence of MCNS as well as atopic skin disease. This increase may have progression of atopic dermatitis, which sometimes heralded., Conclusion: The prohibitin-2 polymorphism may reduce ROS tolerance in glomerular epithelium and led to high local exposure to ROS, increasing permeability of the glomerular basement membrane to result in proteinuria. Imbalance between ROS and antioxidants together with failure of signal transduction in the glomerular slit membrane caused by prohibitin 2 abnormality could have contributed to nephrotic syndrome in our patients. Prohibitin 2 analysis is needed in additional MCNS patients with concomitant allergic disease.

Unbiased transcriptome profiling and functional genomics approaches have identified ubiquitin-specific protease 40 (USP40) as a highly specific glomerular transcript. This gene product remains uncharacterized, and its biological function is completely unknown. Here, we showed that mouse and rat glomeruli exhibit specific expression of the USP40 protein, which migrated at 150 kDa and was exclusively localized in the podocyte cytoplasm of the adult kidney. Double-labeling immunofluorescence staining and confocal microscopy analysis of fetal and neonate kidney samples revealed that USP40 was also expressed in the vasculature, including in glomerular endothelial cells at the premature stage. USP40 in cultured glomerular endothelial cells and podocytes was specifically localized to the intermediate filament protein nestin. In glomerular endothelial cells, immunoprecipitation confirmed actual protein-protein binding of USP40 with nestin, and USP40-small-interfering RNA transfection revealed significant reduction of nestin. In a rat model of minimal-change nephrotic syndrome, USP40 expression was apparently reduced, which was also associated with the reduction of nestin. Zebrafish morphants lacking Usp40 exhibited disorganized glomeruli with the reduction of the cell junction in the endothelium and foot process effacement in the podocytes. Permeability studies in these zebrafish morphants demonstrated a disruption of the selective glomerular permeability filter. These data indicate that USP40/Usp40 is a novel protein that might play a crucial role in glomerulogenesis and the glomerular integrity after birth through the modulation of intermediate filament protein homeostasis., (Copyright © 2017 the American Physiological Society.)

Background . Glomerular upregulation of miR-193a has been detected in primary focal segmental glomerulosclerosis (FSGS) but not in other glomerular diseases. We aimed to isolate exosomes from urine of children with primary FSGS and to assess the diagnostic potential of urinary exosomal miR-193a for primary FSGS. Methods . The first morning urine samples were collected from children with primary FSGS ( n = 8) and minimal change disease (MCD, n = 5). Isolated urinary exosomes were confirmed by electron microscopy and Western blotting. Urinary exosomal microRNA was extracted, and the expression levels of exosomal miR-193a were quantified by real-time PCR. The diagnosis value of urinary exosomal miR-193a levels for primary FSGS was evaluated by ROC analysis. Results . The isolated vesicles were qualitatively compatible with exosomes. The levels of urinary exosomal miR-193a were significantly higher in children with primary FSGS than those in children with MCD. Moreover, the area under the ROC for the diagnosis of primary FSGS using urinary exosomal miR-193a was 0.85. Conclusions . A significant increase in the levels of urinary exosomal miR-193a in primary FSGS patients compared to those in MCD ones was observed. This study suggests that urinary exosomal miR-193a may be a new noninvasive biomarker for the diagnosis of primary FSGS., Competing Interests: The authors declare no conflict of interests.

Background: Nephrotic syndrome (NS) is a debilitating renal problem in children resulting from an interaction between environmental and genetic factors including human leukocyte antigen genes (HLA). The aim of this work was to study the probable link between HLA alleles/haplotypes and NS in south India., Methods: HLA DRB1*/DQB1* alleles were genotyped in 183 NS (76 steroid sensitive-SSNS; 107 steroid resistant-SRNS) and paediatric healthy controls (PHCs; n = 91) using polymerase chain reaction-sequence specific primers (PCR-SSP). HLA-A/-B genotyping was performed for patients (n = 70) positive for DRB1*07-DQB1*02 haplotype to identify four locus extended haplotype., Results: The following alleles and haplotypes were strongly associated with NS (P < 0.05 as significant): DRB1*07 (SSNS, P < 7.98 × 10(-6) ; SRNS, P < 0.008), DQB1*02 (SSNS, P < 3.99 × 10(-6) ; SRNS, P < 0.002), DRB1*07-DQB1*02 (SSNS, P < 1.32 × 10(-4) ; SRNS, P < 0.010), DRB1*07-DQB1*0301,0304 (DQ7) (SSNS, P < 0.001) and DRB1*03-DQB1*02 (SRNS, P < 0.048). Protective associations were observed for alleles DRB1*10 (SRNS, P < 0.013), DQB1*05 (SSNS, P < 4.34 × 10(-6) ; SRNS, P < 0.01), DQB1*06 (SSNS, P < 0.003), and haplotypes DRB1*10-DQB1*06 (SSNS, P < 0.046; SRNS, P < 0.032) and DRB1*15-DQB1*05 (SSNS, P < 0.018). HLA-A/-B typing of 70 NS cases with two locus haplotype DRB1*07-DQB1*02 (70/183; 38.25%) revealed the presence of an extended haplotype 'A*03-B*07-DRB1*07-DQB1*02' (n = 35; 50%)., Conclusion: Our study revealed strong susceptible association of DRB1*07 with SRNS and DQB1*02 with SSNS. A gender predominant protective association was observed for DRB1*10 with SRNS females; DQB1*05 with SSNS and SRNS males. Further, the study documented the presence of an extended haplotype and pleiotropic action of DRB1*/DQB1* alleles in immune-mediated aetiology of NS in south India., (© 2015 Asian Pacific Society of Nephrology.)

Aim: Mutations of LMX1B cause nail-patella syndrome, a rare autosomal dominant disorder. Recently, LMX1B R246Q heterozygous mutations were recognised in nephropathy without extrarenal manifestation. The aim of this study was to clarify characteristics of nephropathy caused by R246Q mutation., Methods: Whole exome sequencing was performed on a large family with nonsyndromic autosomal dominant nephropathy without extrarenal manifestation. Clinical and histological findings of patients with LMX1B mutation were investigated., Results: LMX1B R246Q heterozygous mutation was identified in five patients over three generations. Proteinuria or haematoproteinuria was recognized by urinary screening from all patients in childhood. Proteinuria gradually increased to nephrotic levels and renal function decreased in adolescence. Two patients progressed to end-stage renal disease in adulthood. Renal histology demonstrated minimal change in childhood and focal segmental glomerulosclerosis in adulthood. Using electron microscopy, focal collagen deposition could be detected in glomeruli even when a "moth-eaten appearance" was not apparent in the glomerular basement membrane. In addition, podocin expression in glomerular podocytes was significantly decreased, even in the early stages of disease progression., Conclusion: Comprehensive genetic analyses and collagen or tannic acid staining may be useful for diagnosis of LMX1B-associated nephropathy. While renal prognosis of R246Q may be worse than that of typical NPS nephropathy, signs of podocytopathy can be detected during the infantile period; thus, childhood urinary screening may facilitate early detection., (© 2015 Asian Pacific Society of Nephrology.)

Current therapies used in minimal change disease (MCD) were originally designed to cure other diseases. They are only partially efficient, and present inconvenient side effects. Therefore, understanding the molecular mechanisms implicated in the pathogenesis of proteinuria in MCD could lead to new therapeutic strategies. A new experimental transgenic rat model of human MCD was generated. These NPHS2-Angptl4 transgenic rats over-express two different forms of the glycoprotein Angptl4 from the podocyte. The majority of the protein shows a lack of sialylation that is implicated in the pathogenesis of proteinuria. Supplementation of ManNAc, a precursor of sialic acid, significantly reduces albuminuria in those rats by increasing sialylation of the hyposialylated form of Angptl4. After treatment of the first episode of MCD with glucocorticoids in patients, ManNAc could be used as a maintenance drug, especially to reduce the frequency and intensity of relapse. ManNAc is a promising therapeutic agent for patients with MCD., (© 2016 médecine/sciences – Inserm.)

Background: MicroRNAs (miRNAs) contribute to chronic kidney disease (CKD) progression via regulating mRNAs involved in renal homeostasis. However, their association with clinical outcome remains poorly understood., Materials and Methods: We performed miRNA and mRNA expression profiling on renal biopsy sections by qPCR (miRNA) and microarrays (mRNA) in a discovery (n = 43) and in a validation (n = 29) cohort. miRNAs differentiating stable and progressive cases were inversely correlated with putative target mRNAs, which were further characterized by pathway analysis using KEGG pathways., Results: miR-30d, miR-140-3p, miR-532-3p, miR-194, miR-190, miR-204 and miR-206 were downregulated in progressive cases. These seven miRNAs correlated with upregulated 29 target mRNAs involved in inflammatory response, cell-cell interaction, apoptosis and intra-cellular signalling. In particular, miR-206 and miR-532-3p were associated with distinct biological processes via the expression of their target mRNAs: Reduced expression of miR-206 in progressive disease correlated with the upregulation of target mRNAs participating in inflammatory pathways (CCL19, CXCL1, IFNAR2, NCK2, PTK2B, PTPRC, RASGRP1 and TNFRSF25). Progressive cases also showed a lower expression of miR-532-3p and an increased expression of target transcripts involved in apoptosis pathways (MAP3K14, TNFRSF10B/TRAIL-R2, TRADD and TRAF2). In the validation cohort, we confirmed the decreased expression of miR-206 and miR-532-3p, and the inverse correlation of these miRNAs with the expression of nine of the 12 target genes. The levels of the identified miRNAs and the target mRNAs correlated with clinical parameters and histological damage indices., Conclusions: These results suggest the involvement of specific miRNAs and mRNAs in biological pathways associated with the progression of CKD., (© 2015 Stichting European Society for Clinical Investigation Journal Foundation.)

Background: Paraoxonase1 (PON1) is a serum enzyme bound to high-density lipoproteins with antioxidant properties. Molecular studies of PON1 revealed 2 polymorphic sites at amino acids 55 and 192 resulting in 2 different allozymes, the L and M-genotype at residue 55 and A and B at site 192, respectively. We have studied the association between PON1 gene polymorphisms and the minimal change nephrotic syndrome/focal segmental glomerulosclerosis (MCNS/FSGS) types of idiopathic nephrotic syndrome (INS) in Kuwaiti Arab children., Methods: The PON1 gene, 55 and 192 polymorphisms were analyzed in 50 children with INS (32 MSCN, 18 FSGS) and compared to 50 controls. Serum creatinine, albumin and lipids were measured in all subjects., Results: The LL genotype was detected in 50% of the INS patients compared to 48% of controls (p = 0.84). The heterozygous LM genotype was detected in 42% of INS patients compared 36% of controls (p = 0.68). The MM-genotype was detected in 8% of INS patients and 16% of controls (p = 0.35). The L-allele frequency in its homozygous and heterozygous forms was found in 71% of INS patients compared to 66% controls (p = 0.54). The L-allele frequency (LM and LL) was significantly higher in FSGS compared to MCNS patients (p = 0.0001) and when compared to controls (p = 0.0007). All patients and controls had the AA form of the 192 PON1 gene polymorphism., Conclusion: Our data demonstrate a strong association between the L-allele of PON1 gene 55 polymorphism with FSGS in Kuwaiti Arab children with INS. PON1 genotyping can help in the early prediction of FSGS, which might guide clinicians to a better therapeutic approach., (© 2016 S. Karger AG, Basel.)

Objectives: Soluble urokinase plasminogen activator receptor (suPAR), derived from membrane bound uPAR, is associated with inflammatory diseases. In the present study, we explored the expression of uPAR/suPAR in common biopsy-proven kidney diseases and the relationship between suPAR and staging of type 2 diabetic nephropathy (DN)., Design and Methods: Serum samples for suPAR and renal tissues for uPAR staining were investigated in various common kidney diseases. The levels of serum suPAR were measured and adequate cut-off values of different stage of DN were calculated by receiver operating characteristic (ROC) curve., Results: In our results, the expression of uPAR on renal tissues was pronounced in the majority of kidney diseases. Comparing of expression of uPAR among different kidney diseases, it was strongest in minimal change disease (MCD) and weakest in chronic interstitial nephritis. Serum suPAR in most kidney diseases, except of MCD, was significantly elevated and was highest in DN. As for DN and suPAR, we found that suPAR progressively increased with staging of DN. Moreover, suPAR was linearly and negatively related to estimated glomerular filtration rate and positively related to the amount of proteinuria. By ROC curve, the cut-off values of suPAR in DN for assessing development increased with the progression of the disease., Conclusions: We concluded that uPAR/suPAR is elevated in most kidney diseases and that suPAR is a useful biomarker for assessing stages of DN., (Copyright © 2015 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.)

Objective: To search for biomarkers to differentiate primary focal segmental glomerulosclerosis (FSGS) and minimal change disease (MCD)., Methods: We isolated glomeruli from kidney biopsies of 6 patients with adult-onset steroid sensitiveFSGS and 5 patients with MCD, and compared the profiles of glomerular transcriptomes between the two groups of patients using microarray analysis., Results: Analysis of differential expressed genes (DEGs) revealed that up-regulated DEGs in FSGS patients compared with MCD patients were primarily involved in spermatogenesis, gamete generation, regulation of muscle contraction, response to unfolded protein, cell proliferation and skeletal system development. The down-regulated DEGs were primarily related to metabolic process, intracellular transport, oxidation/reduction andestablishment of intracellular localization. We validated the expression of the top 6 up-regulated and top 6 down-regulated DEGs using real-time PCR. Membrane metallo-endopeptidase (MME) is a down-regulated gene that was previously identified as a key gene for kidney development. Immunostaining confirmed that the protein expression of MME decreased significantly in FSGS kidneys compared with MCD kidneys., Conclusions: This report was the first study to examine transcriptomes in Chinese patients with various glomerular diseases. Expressions of MME both in RNA and protein level decreased significantly in glomeruli of FSGS kidneys compared with MCD kidneys. Our data suggested that MME might play a role in the normal physiological function of podocytes and a decrease in MME expression might be related to podocyte injury. We also identified genes and pathways specific for FSGS versus MCD, and our data could help identify potential new biomarkers for the differential diagnosis between these two diseases.

Podoplanin was identified as a protein associated with the transformation of arborized foot processes of glomerular epithelial cells (podocytes) to flat feet. However, the function of podoplanin in the podocyte is not yet fully clarified. In this study, we analyzed the molecular nature of podoplanin, and its expression in rat nephrotic models and patients with minimal change nephrotic syndrome (MCNS). We demonstrated here that podoplanin has two forms: one contains abundant sialic acid and the other a lesser amount of sialic acid. Podoplanin bound ezrin to interact with the cytoskeleton. The silencing of podoplanin in cultured podocytes caused a change in the cell shape and the distribution of ezrin and actin. The expression of podoplanin was clearly reduced before the onset of proteinuria in puromycin aminonucleoside (PAN) nephropathy, a mimic of MCNS, and the decrease in the expression of podoplanin became more evident at the proteinuric stage. Podoplanin was detected in normal urine samples, and the amount of urinary podoplanin markedly increased on day 1 of PAN nephropathy. Urinary ezrin was also detected. The amount of the phosphorylated ezrin was reduced, while the amount of the podoplanin-interacting ezrin increased. The podoplanin expression was reduced in a patient with active-phase MCNS. It is conceivable that the alteration of the podoplanin-ezrin-cytoskeleton linkage is an important event of the podocyte injury in MCNS.

Podocyte injury plays central roles in proteinuria and kidney dysfunction, therefore, identifying specific biomarker to evaluate earlier podocyte injury is highly desirable. Podocyte-secreted angiopoietin-like-4 (Angptl4) mediates proteinuria in different types of podocytopathy. In the present study, we established an experimental minimal change disease (MCD) rat model, induced by adriamycin (ADR) and resulted in definite podocyte injury, to identify the dynamic changes in Angptl4 expression. We also investigated the direct effects of tacrolimus on Angptl4 and podocyte repair. We determined that the glomerular Angptl4 expression was rapidly upregulated and reached a peak earlier than desmin, an injured podocyte marker, in the ADR rats. Furthermore, this upregulation occurred prior to heavy proteinuria and was accompanied by increased urinary Angptl4. We observed that the Angptl4 upregulation occurred only when podocyte was mainly damaged since we didn't observe little Angptl4 upregulation in MsPGN patients. In addition, we observed the glomerular Angptl4 mainly located in injured podocytes rather than normal podocytes. Moreover, we found that tacrolimus treatment significantly promoted podocyte repair and reduced glomerular and urinary Angptl4 expression at an earlier stage with a significant serum Angptl4 upregulation. And similar results were confirmed in MCD patients. In conclusion, this study represents the first investigation to demonstrate that Angptl4 can predict podocyte injury at earlier stages in MCD and the identification of earlier podocyte injury biomarkers could facilitate the prompt diagnosis and treatment of patients with podocytopathy, as well as determination of the prognosis and treatment efficacy in these diseases.

Background: 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., Methods: 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., Results: 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., Conclusions: CSA monotherapy is effective in SRNS. Discontinuation of CSA is possible in many patients with complete remission.

Background and Objectives: Steroid-resistant nephrotic syndrome is a rare kidney disease involving either immune-mediated or genetic alterations of podocyte structure and function. The rare nature, heterogeneity, and slow evolution of the disorder are major obstacles to systematic genotype-phenotype, intervention, and outcome studies, hampering the development of evidence-based diagnostic and therapeutic concepts. To overcome these limitations, the PodoNet Consortium has created an international registry for congenital nephrotic syndrome and childhood-onset steroid-resistant nephrotic syndrome., Design, Setting, Participants, & Measurements: Since August of 2009, clinical, biochemical, genetic, and histopathologic information was collected both retrospectively and prospectively from 1655 patients with childhood-onset steroid-resistant nephrotic syndrome, congenital nephrotic syndrome, or persistent subnephrotic proteinuria of likely genetic origin at 67 centers in 21 countries through an online portal., Results: Steroid-resistant nephrotic syndrome manifested in the first 5 years of life in 64% of the patients. Congenital nephrotic syndrome accounted for 6% of all patients. Extrarenal abnormalities were reported in 17% of patients. The most common histopathologic diagnoses were FSGS (56%), minimal change nephropathy (21%), and mesangioproliferative GN (12%). Mutation screening was performed in 1174 patients, and a genetic disease cause was identified in 23.6% of the screened patients. Among 14 genes with reported mutations, abnormalities in NPHS2 (n=138), WT1 (n=48), and NPHS1 (n=41) were most commonly identified. The proportion of patients with a genetic disease cause decreased with increasing manifestation age: from 66% in congenital nephrotic syndrome to 15%-16% in schoolchildren and adolescents. Among various intensified immunosuppressive therapy protocols, calcineurin inhibitors and rituximab yielded consistently high response rates, with 40%-45% of patients achieving complete remission. Confirmation of a genetic diagnosis but not the histopathologic disease type was strongly predictive of intensified immunosuppressive therapy responsiveness. Post-transplant disease recurrence was noted in 25.8% of patients without compared with 4.5% (n=4) of patients with a genetic diagnosis., Conclusions: The PodoNet cohort may serve as a source of reference for future clinical and genetic research in this rare but significant kidney disease., (Copyright © 2015 by the American Society of Nephrology.)

Background: MicroRNAs (miRNAs) are noncoding RNA molecules that play important roles in the pathogenesis of various kidney diseases. We investigated whether patients with minimal change disease (MCD) and focal segmental glomerulosclerosis (FSGS) have distinct circulating and urinary miRNA expression profiles that could lead to potential development of noninvasive biomarkers of the disease., Materials and Methods: Exosome miRNAs were extracted from plasma and urine samples of patients with primary FSGS (n = 16) or MCD (n = 5) and healthy controls (n = 5). Differences in miRNA abundance were examined using Affymetrix GeneChip miRNA 3.0 arrays. QRT-PCR was used to validate the findings from the array., Results: Comparison analysis of FSGS versus MCD revealed 126 and 155 differentially expressed miRNAs in plasma and in urine, respectively. Only 38 of these miRNAs were previously cited, whereas the remaining miRNAs have not been described. Comparison analysis showed that a significant number of miRNAs were downregulated in both plasma and urine samples of patients with FSGS compared to those with MCD. Plasma levels of miR-30b, miR-30c, miR-34b, miR-34c and miR-342 and urine levels of mir-1225-5p were upregulated in patients with MCD compared to patients with FSGS and controls (P < 0.001). Urinary levels of mir-1915 and miR-663 were downregulated in patients with FSGS compared to MCD and controls (P < 0.001), whereas the urinary levels of miR-155 were upregulated in patients with FSGS when compared to patients with MCD and controls (P < 0.005)., Conclusions: Patients with FSGS and MCD have a unique circulating and urinary miRNA profile. The diagnostic and prognostic potential of miRNAs in FSGS and MCD warrants further studies., (© 2015 Stichting European Society for Clinical Investigation Journal Foundation.)

Immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome (OMIM 304790) is a rare hereditary disorder of the immune regulatory system caused by FOXP3 mutations. The clinical features of this syndrome include a wide spectrum of severe autoimmune diseases and renal involvement, mostly due to tubulointerstitial diseases, in some patients. Glomerulopathy of membranous nephropathy (MN) and minimal change nephrotic syndrome (MCNS), however, have also been reported. We encountered two children with IPEX syndrome from the same family. Interestingly, they had different glomerular lesions: one had MN and the other had MCNS. Herein we describe the cases of these siblings and review the possible mechanisms for the development of two different renal lesions., (© 2015 Japan Pediatric Society.)

Background: 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., Methods: 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., Results: 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., Conclusions: 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.

Podocyte damage and loss together have an important role in the pathogenesis and progression of glomerulonephritis. Glomerulonephritis patients and healthy controls were enrolled in this study. Biochemical, clinical and experimental procedures included measurement of total urinary protein, renal biopsy and gene expression analysis of the receptor activator of NF-kappaB (RANK). The urinary mRNA levels of RANK were significantly higher in the glomerulonephritis group compared to the controls. The urinary RANK level of glomerular subtypes was correlated significantly with proteinuria. The calculated area of RANK mRNA levels under the curve was 0.61 for minimal change disease (MCD), 0.97 for membranous nephropathy (MN), 0.65 for IgA nephropathy (IgAN), 0.70 for lupus nephritis (LN) and 0.70 for focal segmental glomerulosclerosis (FSGS). The urinary mRNA of RANK might be used to differentiate histologic subtypes of glomerulonephritis, particularly between MCD and MN.

The patients with CD3γ deficiency can present with different clinical findings despite having the same homozygous mutation. We report three new CD3gamma-deficient siblings from a consanguineous family with a combined T-B+NK+ immunodeficiency and their variable clinical and cellular phenotypes despite the same homozygous mutation of the CD3G gene (c.80-1G>C). We also re-evaluate a previously reported non-consanguineous family with two CD3gamma-deficient siblings with the same mutation. The median age at diagnosis was 11 years (14 months-20 years). We found all five patients to display autoimmunity: autoimmune thyroiditis (n = 5), autoimmune haemolytic anaemia (n = 2), immune thrombocytopenia (n = 1), autoimmune hepatitis (n = 1), minimal change nephrotic syndrome (n = 1), vitiligo (n = 1) and positive antinuclear antibodies (n = 3) as well as high IgE (n = 2) and atopic eczema (n = 2). While CD3(+) TCRαβ+T cell percentages were low in all patients, only one had lymphopenia and 3 had CD3(+) T cell lymphopenia. Strikingly, we report frequent and multiple autoimmunity in tested heterozygous carriers in both families (n = 6; in 67%), and frequent autoimmunity in family members not available for testing (n = 5, in 80%). The results suggest that CD3G should be studied as a candidate gene for autoimmunity and that CD3gamma deficiency should be considered among other primary immunodeficiencies with predominantly autoimmune manifestations., (© 2014 John Wiley & Sons Ltd.)

Background: The pathogenesis of primary nephrotic kidney diseases is not completely understood. As T-cell involvement is suspected, cytotoxic T-lymphocyte antigen 4 (CTLA-4) expressed on activated T cells could play a role in the immune response. Single-nucleotide polymorphisms (SNPs) in the CTLA-4 gene are associated with several autoimmune-related diseases., Methods: Our goal was to study the occurrence of the SNPs -318C/T, +49A/G and CT60 on the CTLA-4 gene in healthy blood donors (N = 156) compared with nephrotic patients with biopsy-proven minimal-change disease (MCD, N = 160), focal segmental glomerulosclerosis (FSGS, N = 159) and membranous nephropathy (MN, N = 185). Odds ratios (ORs) with 95% confidence intervals (95% CIs) were calculated to estimate the strength of the association., Results: The +49GG genotype was significantly (P < 0.001) associated with the risk for MCD, FSGS and MN (AA versus GG: OR = 3.403, 95% CI = 1.748-6.622, OR = 3.846, 95% CI = 1.945-7.604 and OR = 2.381, 95% CI = 1.257-4.511, respectively). No further significant associations, neither with the heterozygous genotype of +49A/G nor for the -318C/T or CT60 SNP, were detected., Conclusions: The +49GG genotype of the +49A/G SNP in the CTLA-4 gene is associated with the risk for MCD, FSGS and MN, suggesting a possible role for CTLA-4 in a proposed common final pathway in the pathogenesis of primary nephrotic kidney diseases.

The Nephrotic Syndrome Study Network (NEPTUNE) is a North American multicenter collaborative consortium established to develop a translational research infrastructure for nephrotic syndrome. This includes a longitudinal observational cohort study, a pilot and ancillary study program, a training program, and a patient contact registry. NEPTUNE will enroll 450 adults and children with minimal change disease, focal segmental glomerulosclerosis, and membranous nephropathy for detailed clinical, histopathological, and molecular phenotyping at the time of clinically indicated renal biopsy. Initial visits will include an extensive clinical history, physical examination, collection of urine, blood and renal tissue samples, and assessments of quality of life and patient-reported outcomes. Follow-up history, physical measures, urine and blood samples, and questionnaires will be obtained every 4 months in the first year and biannually, thereafter. Molecular profiles and gene expression data will be linked to phenotypic, genetic, and digitalized histological data for comprehensive analyses using systems biology approaches. Analytical strategies were designed to transform descriptive information to mechanistic disease classification for nephrotic syndrome and to identify clinical, histological, and genomic disease predictors. Thus, understanding the complexity of the disease pathogenesis will guide further investigation for targeted therapeutic strategies.

Background: Steroid-sensitive idiopathic nephrotic syndrome (SSINS) is most often encountered in sporadic cases of minimal change disease (MCD). Only rare cases of familial forms of MCD have been reported and most of them only in one generation. The scarcity of data has precluded unraveling the underlying genetic defect and candidate gene approaches have been unsuccessful. Here we report two families with related SSINS cases and review the related literature., Case Presentation: Two siblings and a cousin (first family), and a father and his son (second family), are reported with SSINS due to MCD. Patients have been followed up for more than 12 years and a renal biopsy was performed in three cases, demonstrating typical features of MCD. The course of the disease was remarkable because of several relapses treated with steroids. In three cases, mycophenolate mofetil or cyclosporine was added., Conclusion: Familial SSINS due to MCD is extremely rare and no genetic defect has been identified so far. Reporting cases of hereditary MCD will allow further genetic studies which will ultimately help unravel the molecular basis of this disease.

α-Actinin 4, encoded by ACTN4, is an F-actin crosslinking protein which belongs to the spectrin gene superfamily. It has a head-to-tail homodimer structure with three main domains. Mutations in ACTN4 are associated with idiopathic nephrotic syndrome (NS). However, until today only a few mutations have been described in this gene. We used genomic DNA of 48 patients with focal segmental glomerulosclerosis (FSGS) and minimal change disease (MCD) to screen for ACTN4 mutations by high-resolution melting analysis (HRM). Suspect samples were sequenced and compared with healthy controls. To investigate the prevalence and possible effect of some substitutions found in FSGS/MCD patients we also looked for these changes in patients with IgA nephropathy (IgAN) and membranous glomerulonephritis (MGN). We found 20 exonic and intronic substitutions in the group of 48 Czech patients. The substitution 2242A>G (p.Asn748Asp) is a candidate mutation which was identified in one patient but not in any of the 200 healthy controls. Exon 19 seems to be a variable region due to the amount of revealed polymorphisms. In this region we also found three unreported substitutions in IgAN patients, c.2351C>T (p.Ala784Val), c.2378G>A (p.Cys793Tyr) and c.2393G>A (p.Gly798Asp). These substitutions were not found in any tested healthy controls. To conclude, the ACTN4 mutations are not a frequent cause of FSGS/MCD in Czech adult patients. One new ACTN4 mutation has been identified.

Background: DNA methylation of gene promoters is associated with transcriptional inactivation. Changes in DNA methylation can lead to differences in gene expression levels and thereby influence disease development. We hypothesized that epigenetics underlies the pathogenesis of minimal change nephrotic syndrome (MCNS)., Methods: Genome-wide DNA methylation changes between relapse and remission in monocytes (n = 6) and naive T helper cells (Th0s) (n = 4) isolated from patients with MCNS were investigated using the microarray-based integrated analysis of methylation by isochizomers (MIAMI) method. We confirmed the MIAMI results using bisulfite-pyrosequencing analysis. Expression analysis was performed using quantitative real-time PCR., Results: Three gene loci (GATA2, PBX4, and NYX) were significantly less methylated in Th0s during relapse than in remission, compared to none in monocytes. In addition, the distance distribution from the regression line of all probes in MIAMI was significantly different between monocytes and Th0s. The mRNA levels of the three genes in Th0s were not significantly different between relapse and remission., Conclusions: Our results demonstrate that the change in DNA methylation patterns from remission to relapse in MCNS occurs predominantly in Th0s rather than in monocytes and suggest that epigenetic regulation in Th0s underlies the pathogenesis of MCNS.

Nephrotic syndrome (NS) presented within three weeks in siblings aged six and ten years. Both children experienced proteinuria, hypoalbuminaemia and oedema, with the most pronounced symptoms in the older. Standard treatment with prednisolone led to remission of the nephrotic syndrome in the younger, whereas the older required additional therapy with tacrolismus before remission. In view of the low incidence of NS in children, a near simultaneously onset in two siblings must lead to genetic elucidation. Genetic disorders and other causes of childhood NS are discussed.

Objective: 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)., Methods: 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., Results: (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)., Conclusions: 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.

Aims: To further elucidate the clinical relevance of T-cell abnormalities in minimal change nephrotic syndrome (MCNS), and to predict the consequences of MCNS, we studied T-cell receptor (TCR) diversity by analyzing CDR3 size distribution and the frequency of Vβ repertoire usage., Methods: Participants comprised 36 pediatric patients with MCNS. 18 were frequent relapsers (FRs) and/or steroid-dependent (SD) and 18 were non-frequent relapsers (NFRs). Serial changes in TCR Vβ repertoires were analyzed for these two groups of patients. Frequencies of Vβ repertoire usage were determined by flow cytometry, and TCR CDR3 length distribution was analyzed by GeneScan., Results: In NFRs, abnormalities in the distribution of Vβ repertoires were few in both CD4+ and CD8+ T cells. In FRs/ SD patients, patterns were normal in CD4+ T cells, while selected Vβ repertoires were significantly increased in CD8+ T cells in some patients. Furthermore, TCR diversity was significantly reduced in CD8+ T cells in FRs/SD patients, as shown by marked skewing of CDR3 size distributions. Of note was the finding that some FRs/SD patients showed improvements in the initially abnormal TCR diversity with improvement in clinical symptoms, eventually becoming NFRs., Conclusion: Analysis of TCR diversity may delineate the subgroup of FRs/SD patients and provide a rationale for early intervention with immunosuppressive therapy for these patients.

Introduction: Imbalance between T-helper 1 (Th1) and 2 (Th2) lymphocytes and effects of reactive oxygen species (ROS) upon glomerular capillary walls have been implicated in minimal change nephrotic syndrome (MCNS)., Methods: By polymerase chain reaction and comparative genomic hybridization, we evaluated mutations of the GSTT1 gene (GSTT1), a member of the glutathione S-transferase (GST) supergene family associated with both protection of cells from ROS and control of allergic reactions and serum immunoglobulin (Ig) E., Results: Among 15 children with MCNS, IgE elevation (over 2,000 IU/l) and GSTT1 deletion was found in 2 who showed severe allergic symptoms. Serum ROS concentrations in these 2 patients were significantly higher than in healthy controls or other MCNS patients. In addition, a Th2 shift caused by increased serum interleukin (IL)- 4 was observed., Conclusion: These results suggest presence of a GSTT1 abnormality in some children with MCNS having marked serum IgE elevations and various allergic complications. Defective ROS degradation and Th1/Th2 imbalance caused by GSTT1 abnormality could initiate proteinuria leading to MCNS.

Backgrounds/aims: We previously reported that fibroblast-specific protein 1 (FSP1) is a marker of epithelial-mesenchymal transition (EMT) in tubulointerstitial fibrosis. The EMT-like changes observed in podocytes are reportedly associated with podocyte detachment which may cause focal glomerulosclerosis., Methods: In cross-sectional studies, we analyzed podocyte expression of FSP1 immunohistochemically using renal biopsy specimens from 31 patients with focal segmental glomerulosclerosis (FSGS) and 39 patients with minimal change disease (MCD). We also semiquantitatively analyzed glomerular expression of FSP1 mRNA using laser capture microdissection and real-time PCR., Results: We found that FSP1 was localized to podocytes in both FSGS and MCD patients; however, the number of FSP1(+) podocytes per glomerular profile was significantly higher in patients with FSGS than in those with MCD, and there was a corresponding difference in the levels of FSP1 mRNA. FSP1(+) podocyte counts per glomerular profile in FSGS patients correlated significantly with the prevalence of glomerulosclerosis and the extent of interstitial type-I collagen-positive areas., Conclusion: Taken together, these data suggest that podocyte expression of FSP1 could shed light on the potential linkage between EMT-like changes, detachment of podocytes from the glomerular basal membrane and the pathophysiology underlying FSGS., (Copyright © 2011 S. Karger AG, Basel.)

Immune mechanisms underlying the pathophysiology of idiopathic nephrotic syndrome, the most frequent glomerular disease in children, are believed to involve a systemic disorder of T cell function and cell mediated immunity. How these perturbations take place remains unclear. We report here that NFRKB, a member of the chromatin remodeling complex, is upregulated in MCNS relapse, mainly in CD4+T cells and B cells and undergo post-translational modifications including sumoylation. We showed that NFRKB was highly expressed in nuclear compartment during the relapse, while it was restricted to cytoplasm in remission. NFRKB induced the activation of AP1 signaling pathway by upregulating the expression of c-jun. We showed that NFRKB promotes hypomethylation of genomic DNA, suggesting its implication in regulation of gene expression by enhancing the binding of transcription factors through chromatin remodeling. These results suggest for the first time that NFRKB may be involved in the disorders of transcriptional regulation commonly observed in MCNS relapse.

Blood filtration and formation of primary urine in the kidney glomerulus is provided by a specialized membrane called slit diaphragm located between well-branched pedicels of podocytes. Actually, the slit diaphragm is a protein supercomplex, whose disruption can cause failure of renal filtration, and patients usually manifest nephrotic syndrome. Recently, familial forms of nephrotic syndrome have been described which arise from malfunction of mutated proteins making up the slit diaphragm. In 2005 it was found that one of the proteins present in this complex was non-selective cation channel TRPC6. The aim of this work was to screen mutations and polymorphisms of the TRPC6 gene in a group of 64 Czech patients with nephrotic syndrome and subsequently, on the basis of these data, evaluate the role of mutations in the TRPC6 gene in Czech population. The analysis was performed by the PCR method followed by direct sequencing and high-resolution melting method. We have not identified any mutations in our group of patients. Two additional single nucleotide polymorphisms - p.P15S and p.A404V - were detected along with nucleotide changes that did not result in amino acid changes and with a few intronic changes. P.P15S heterozygotes were more frequent in patients with steroid-resistant FSGS than in steroid- sensitive patients (29 % versus 12.1 %). To conclude, we did not find any probable disease-causing mutation in the TRPC6 gene in the cohort of 64 Czech patients. The p.P15S polymorphism might have some influence on the therapeutic response of FSGS patients.

It has been shown that angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism affects the circulating and cellular levels of ACE and may be a risk factor in several renal diseases. We analyzed the association of ACE gene I/D polymorphism with the clinical presentation of minimal change nephrotic syndrome (MCNS) in a Turkish child population. This study consisted of 97 children with MCNS and 144 healthy controls. Genotyping of ACE gene was performed using polymerase chain reaction (PCR). The distributions of ACE genotypes were II in 13%, ID in 49%, and DD in 38% in patient group, and 9%, 49%, and 42% in control group, respectively. The frequency of the D allele was 63% and that of the I allele was 37% in patients. There were no relevant differences in the allele frequencies and genotypes of ACE I/D polymorphism between patients and controls. However, DD genotype was higher in boys in children with MCNS (78.4%. vs. 50.0%, p = 0.004). The frequencies of DD genotype and D allele in boys were 7.25 and 2.56 times higher than II genotype and I allele in the patient group, respectively. We suggest that DD genotype in boys may be one of the risk factors for MCNS.

Background: 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., Methods: 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., Results: 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)., Conclusion: 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.