Pathogenesis Of Idiopathic Nephrotic Syndrome Research Articles

#2553 Circulating anti-slit diaphragm NEPHRIN and KIRREL-2 antibodies associate with nephrotic syndrome

Abstract Background and Aims Pathogenesis of Idiopathic Nephrotic Syndrome (INS) is still largely unknown. Recently, circulating anti-NEPHRIN antibodies have been proposed as responsible of disarrangement of the slit diaphragm architecture upon glomerular deposition. However, previous experience referred to limited cases and controls with different ELISA assays for antibodies detection. We compared the performance of three different ELISA assays quantifying circulating anti-NEPHRIN antibodies and we developed ELISA assays to quantify circulating antibodies against two proteins homologous of NEPHRIN, the KIRREL.1 and KIRREL-2. Method We compared the performance of three different ELISA assays, two against the extracellular (aa 1-1055NEPHRIN-A and aa 23-1029 NEPHRIN-B) and one against the intracytoplasmic (aa 1160-1241 NEPHRIN-C) domain of NEPHRIN. We tested a large cohort of 166 patients (396 serum samples) with INS, 32 focal segmental glomerulosclerosis kidney transplant recipients, 143 healthy controls and 40 lupus nephritis and membranous nephropathy, respectively. Furthermore, to investigate sensitivity and specificity of circulating anti-NEPHRIN antibodies, we developed ELISA assays to quantify circulating antibodies against two proteins homologous of NEPHRIN, the KIRREL-1 and KIRREL-2. We tested NEPHRIN and KIRREL-2 gene expression among glomeruli in kidney biopsies from 4 FSGS patient and 4 controls. Results Serum levels of anti-NEPHRIN antibodies against the two extracellular domains were highly correlated, but differed significantly to the levels detected using the intracytoplasmic domain of NEPHRIN. Neither the circulating anti-NEPHRIN targeting the extracellular nor the intracellular domains of the protein could differentiate INS patients overall from healthy controls (Fig. 1A). However, after age stratification, we found that circulating anti-NEPHRIN antibodies against the extracellular domain were significatively higher in INS than in healthy controls >6 years old (Fig. 1B).Circulating anti-NEPHRIN antibodies against extracellular domain appeared more specific for INS than anti-NEPHRIN antibodies against cytoplasmic domain. Circulating anti-NEPHRIN antibodies did not correlate with disease activity nor FSGS recurrence after kidney transplant (Fig. 1C). Of note, circulating anti-KIRREL-2 antibodies could differentiate INS and healthy controls more effectively than anti-NEPHRIN antibodies (Fig. 1D). We than confirmed that KIRREL-2 is transcript in glomeruli (Fig. 1E) and, in line with circulating anti-KIRREL-2 antibodies, spatial transcriptomic analyses showed that KIRREL-2 is increased in FSGS than in controls. Conclusion In a large cohort of patients, we showed that circulating anti-NEPHRIN antibodies are positive in a subset of INS and FSGS recurrence. However, they are not associated with disease activity and the circulating levels appeared as age related. Circulating anti-KIRREL-2 antibodies are more strongly associated with INS. Therefore, based on our findings, several podocyte antigens may be supposed target for specific autoantibodies in INS.

The Role of TNF-α in the Pathogenesis of Idiopathic Nephrotic Syndrome and Its Usefulness as a Marker of the Disease Course.

Background: The pathogenesis of idiopathic nephrotic syndrome (INS) has not been fully explained. Among the likely factors, tumor necrosis factor - alpha (TNF-α) is considered. We aimed to evaluate the TNF-α (sTNF-α, uTNF-α) levels in the serum and urine of INS children, with the aim of determining its association with proteinuria, and of determining its usefulness as a marker of the disease severity. Methods: Fifty-one examined patients were divided into subgroups depending on the number of relapses as follows: group IA-first episode; group IB-more than two relapses, and according to treatment modality; group IIA-glucocorticosteroids (GS) alone; and group IIB-GS with immunosuppressants. Healthy age-matched children served as the control group. Results: sTNF-α and uTNF-α levels were significantly increased in active phases in the whole INS group compared to the control group. They decreased in remission, but remained significantly higher when compared to the control group. During remission in the IB group, sTNF-α levels were significantly higher than in IA, whereas, in the relapse phase, these values were similar. In the IA group, a positive correlation between proteinuria and sTNF-α was demonstrated. Conclusions: Our findings suggest that TNF-α plays a role in the development of INS, and may be used as a prognostic marker, as well as an indicator for the continuation of therapy. Additional research is required to verify this statement.

T-cell and B-cell repertoire diversity are selectively skewed in children with idiopathic nephrotic syndrome revealed by high-throughput sequencing.

Clinical studies suggest that the dysfunction of T cells and B cells may play an essential role in the pathogenesis of idiopathic nephrotic syndrome (INS), but laboratory evidence is lacking. Therefore, this study explored T-cell receptor (TCR) and B-cell receptor (BCR) profiling in children with idiopathic nephrotic syndrome. High-throughput sequencing technology was used to profile the TCR and BCR repertoires in children with INS. Peripheral blood was collected from ten INS patients, including five vinculin autoantibody-positive patients and five vinculin autoantibody-negative patients, before and after treatment. TCR and BCR libraries were constructed by 5'-RACE and sequenced by a DNBSEQ-T7 sequencer, and sequence analyses were performed using ReSeqTools, FastP, MiXCR, and VDJtools. The TRA (T-cell receptor α), TRG (T-cell receptor γ), and IGH (immunoglobulin heavy chain) repertoires of the INS group were occupied by highly abundant clonotypes, whereas small clonotypes occupied the healthy group, especially TRA. A significant increase in the Shannon-Weaver index was observed for the TRA and TRG repertoires after treatment in vinculin autoantibody-negative patients, but a significant increase in the IGH repertoire after treatment was observed in vinculin autoantibody-positive patients. The frequency of some V-J pairs was significantly enriched in steroid-sensitive nephrotic syndrome patients. The usage frequency of the V and J genes was skewed in patients, which seemed not related to immunosuppressive therapy. However, after effective treatment, dynamic changes in the size of the individual clonotype were observed. T-cell and B-cell immunity contribute to the pathogenesis of different INSs. Video: (MP4 99,786KB).

The role of cationic channels of the potential TRPC receptor in the pathogenesis of idiopathic nephrotic syndrome in children

Idiopathic nephrotic syndrome is the most common glomerulopathy in children, with a prevalence of approximately 16 per 100,000 of child population worldwide. Any chronic glomerular disease has the same type of development mechanism. Regardless of the damaging factor, after the death of a significant part of the nephrons, there occurs a steady decrease in the glomerular filtration rate, while morphologically we most often determine focal segmental glomerulosclerosis. Studying the causes of focal segmental glomerulosclerosis is an urgent problem in pediatric nephrology. Recently, there has been discussed the role of the cation channels of the potential receptor TRPC of podocytes in the development of proteinuria and focal segmental glomerulosclerosis. The article provides data on the role of TRPC receptors in the pathogenesis of focal segmental glomerulosclerosis. The authors present their our own data demonstrating gene expression of the cationic channels family of the potential receptor TRPC1, TRPC3, TRPC4, TRPC5 and TRPC6 in children with idiopathic nephrotic syndrome, depending on the morphological picture of the disease and sensitivity to steroid therapy.

Involvement of Hemopexin in the Pathogenesis of Proteinuria in Children with Idiopathic Nephrotic Syndrome.

Hemopexin (Hpx) is considered a factor in the pathogenesis of idiopathic nephrotic syndrome (INS). The aim of the study was to evaluate the serum and urine values of Hpx (sHpx and uHpx) in children with INS, analyze the role of Hpx, and assess its usefulness as a marker of the disease course. 51 children with INS and 18 age-matched controls were examined. Patients were divided into subgroups depending on the number of relapses (group IA—the first episode of INS, group IB—with relapses) and according to method of treatment (group IIA treated with gluco-corticosteroids (GCS), group IIB treated with GCS and other immunosuppressants). Hpx concentrations were determined by enzyme-linked immunosorbent assay (ELISA). sHpx and uHpx values in relapse were elevated in the whole INS group versus controls (p < 0.000). In remission their levels decreased, but still remained higher than in the control group (p < 0.000). In group IB uHpx levels were increased during remission as compared to group IA (p < 0.006). No significant impact of immuno-suppressants on sHpx was observed, but uHpx excretion in group IIA was higher in relapse (p < 0.026) and lower in remission (p < 0.0017) as compared to group IIB. The results suggest the role of Hpx in the pathogenesis of INS. Hpx may be a useful indicator for continuation of treatment, but it requires confirmation by further controlled studies.

Function of miR-24 and miR-27 in Pediatric Patients With Idiopathic Nephrotic Syndrome.

Purpose: We investigated the pathogenesis of idiopathic nephrotic syndrome (INS) by measuring the effects two specific miRNAs on Th2 cells in children with this disease.Methods: After informed consent, we enrolled 20 children with active INS before steroid initiation, 20 children with INS in remission after steroid therapy, and 20 age-matched healthy controls. Flow cytometry was used to measure the levels of Th2 cells and a cytometric bead array was used to measure the levels of IgE, interleukin (IL)−4, and IL-13. RT-PCR was used to measure the levels of miR-24 and miR-27 in CD4+TCD25− cells. PBMCs were isolated using Ficoll density gradient centrifugation, and transfected with different mimic or inhibitor miRNAs. RT-PCR was used to measure the expression of different RNAs, and flow cytometry was used to determine the percentage of Th2 cells.Results: Relative to healthy controls, children with active INS had higher percentages of Th2 cells (P < 0.05), but there was no significant difference in controls and children in remission. The plasma levels of IgE, IL-4, and IL-13 were significantly increased in children with active INS (P < 0.05). There were lower levels of miR-24 and miR-27 in children with active non-atopic INS (P < 0.05). Transfection experiments indicated that upregulation of each miRNA decreased the percentage of Th2 cells and the level of IL-4 (P < 0.05), and down-regulation of each miRNA had the opposite effects (P < 0.05).Conclusion: Children with active INS, with or without atopy, had higher levels of IgE, possibly related to their higher levels of IL-13 and IL-4 due to a drift toward Th2 cells. miR-24 and miR-27 suppressed the expression of Th2 cells and have a critical function regulating Th2 cell expression in INS.

Immunopathogenesis of idiopathic nephrotic syndrome in children: two sides of the coin.

Idiopathic nephrotic syndrome is a common form of glomerular nephropathy in children, with an incidence rate of 1.15-16.9/100,000 depending on different nationalities and ethnicities. The etiological factors and mechanisms of childhood idiopathic nephrotic syndrome have not yet been fully elucidated. This review summarizes the progress of the immunopathogenesis of idiopathic nephrotic syndrome in children. We review the literature on the immunopathogenesis of idiopathic nephrotic syndrome in children. Databases including Medline, Scopus, and Web of Science were searched for studies published in any language with the terms "children", "idiopathic nephrotic syndrome", "immunopathogenesis", "T cells", "circulating permeability factors", and "B cells". Dysfunction in T lymphocytes and pathogenic circulatory factors were indicated to play key roles in the pathogenesis of idiopathic nephrotic syndrome. Recently, some studies have shown that cellular immune dysfunction may also be involved in the pathogenesis of idiopathic nephrotic syndrome. Both T- and B-cell dysfunction may play significant roles in the pathogenesis of idiopathic nephrotic syndrome, like two sides of one coin, but the role of B cell seems more important than T cells.

Predictive Value of Serum Interleukins in Children with Idiopathic Nephrotic Syndrome.

Pro-inflammatory cytokines have been suggested in the pathogenesis of idiopathic nephrotic syndrome (INS), with conflicting results. This study was performed to identify alteration of different serum interleukins (ILs) in children with INS, and their predictive value in response to steroid treatment. Three groups of children (27; steroid-sensitive INS, 21; steroid-resistant INS, and 19 healthy controls) with normal serum C3, negative serologic tests of hepatitis B virus (HBV), hepatitis C virus (HCV), human immune deficiency virus (HIV), and parasitic infections were included in this study. Serum concentrations of IL-1β, IL-2, IL-6, IL-8, IL-13, and IL-18 were measured, using quantitative colorimetric sandwich ELISA kits. Children with secondary nephrotic syndrome, inflammations, systemic disorders, and chronic kidney disease were excluded. The serum concentration of all ILs; except IL-13 and IL-18; was significantly higher in children with INS, compared with the healthy controls. Serum IL-2 had the highest sensitivity of (95.24%) in patients with INS. All of the serum ILs had acceptable accuracy in children with INS, compared with the control group. The serum concentration of IL-1β, IL-6, and IL-8 was significantly higher in children with steroid-sensitive nephrotic syndrome (SSNS), compared with steroid-resistant nephrotic syndrome (SRNS). All of these ILs had acceptable accuracy for the prediction of steroid response in patients with INS. Our findings suggested the pathogenic role of pro-inflammatory cytokines in children with INS, of which IL-1β, IL-6, and IL-8 were accurate biomarkers for the prediction of steroid response in these patients.

Phenotypes of B-Lymphocytes as a Predictor of Steroid Response in Idiopathic Nephrotic Syndrome.

Introduction: The pathogenesis of Idiopathic nephrotic syndrome (INS) is not clear, where the role of B-cells is not yet illustrated. Aim of the study: To evaluate B- cells subsets as a predictor of steroid therapy sensitivity among INS at initial onset. Methods: 45 children with idiopathic nephrotic syndrome were recruited in a follow- up study, patients were divided into steroid-sensitive nephrotic syndrome (SSNS) and steroid-resistant nephrotic syndrome (SRNS) groups based on their sensitivities to steroids. Venous blood samples were drawn from all children for assessment of memory B- cell population before and after one year of steroid therapy. Results: We found statistically significant relation between steroid response and total memory CD19+ CD27+B cell at disease onset where it was higher in SSNS group. Our results showed The best cut-off of total CD19+ B cells in predicting steroid response was ≥32.7 with an area under curve (AUC) of 0.445, a sensitivity of 43.9%, a specificity of 50%, a positive predictive value (PPV) of 90%, a negative predictive value (NPV) of 8% and an accuracy of 44.4% (p>0.05) We also found that The best cut-off of CD19+ CD 27+ total memory B cells in predicting steroid response was ≥32 with an AUC of 0.817, a sensitivity of 78%, a specificity of 75%, a PPV of 97%, a NPV of 25% and an accuracy of 77.8% (p < 0.05). Conclusion: CD19+ CD 27+ total memory B cells could help in predicting steroid response among INS patients with a cut-off of total CD 19+B cells above 32.7 and PPV of 90% , a cut-off above 32 in CD19+ CD +27 total memory cells and PPV 97%.

Immunologic pathogenesis of idiopathic nephrotic syndrome in children: the present and future

Immunologic pathogenesis of idiopathic nephrotic syndrome in children: the present and future

Kidney–Targeted drug delivery systems based on tailor-made nanocapsules

Podocyte damage plays a central role in the pathogenesis of idiopathic nephrotic syndrome, as well as in the progression of many chronic glomerular diseases. Targeted therapy in these diseases still represents a challenge. We have previously shown that c-mip (c-maf inducing protein) plays a pivotal role in podocyte diseases in minimal change nephrotic syndrome patients. In this context, we implement a non-viral approach targeting the expression of c-mip in podocytes to reduce proteinuria. This therapeutic approach is based on nanovectors composed by chitosan and plasmids coding for micro-Ribonucleic Acid (miRNA) against c-mip. The overall elaboration process, monitored by absorbance and zeta potential measurements, relies on the alternate deposition of these biopolymers with opposite charges onto gold colloidal nanoparticles used as solid template (characterized by transmission electron microscopy TEM and Small-angle X-ray scattering SAXS measurements). Their hydrolysis lead to hollow nanostructures, also called nanocapsules (evidenced by TEM analysis). From this approach, crucial parameters impacting the biological assay can be easily investigated in particular (i) the size, (ii) the number of plasmid layers and (iii) the presence of the solid template. The efficiency of the synthesized nanomaterial will be tested in different conditions on Human Embryonic Kidney cells (HEK), immortalized podocytes and in vivo on a mouse podocyte damage model. To our knowledge, this is the first experiment including designed Deoxyribonucleic acid (DNA) derived nanocapsules to reach podocytes.

Interferon gamma: is it a co-player in the pathogenesis of idiopathic nephrotic syndrome?

Introduction: Idiopathic nephrotic syndrome (INS), the most common form of NS in childhood, was considered 4 decades ago as a systemic disorder of T cells, mediated through its released cytokines. To date, the exact incriminated cytokine or immunological mediator is not properly defined. Interferon-gamma (IFN-gamma), a pro-inflammatory cytokine, is thought to have a role in the provocation of the T cell-mediated INS relapse, through the promotion of T helper1 (Th1) differentiation and suppression of regulatory T cells (Treg). Aim of the study: To evaluate the immunopathogenic role of IFN-gamma in children with steroid-sensitive idiopathic nephrotic syndrome (SSNS) through monitoring the changes in its levels with disease course. Methods: This study included twenty-five newly diagnosed children with SSINS. They were all given full dose prednisolone, evaluated at initial diagnosis and at full remission as regards the serum level of IFN-gamma. Results: Serum levels of IFN-gamma were lowermost at the time of diagnosis and increased with remission on corticosteroids. Conclusions: This study points to a role for the lower serum IFN-gamma at diagnosis, in the immunopathogenesis of INS than at remission and the rise in its serum level might be a marker of remission induction, however, this awaits confirmation in larger-scale studies. Studies on renal biopsy specimens are needed to determine the exact renal in situ levels and effects of IFN-gamma

Several reasons for the development of proteinuria in nephrotic syndrome

The review discusses some of the causes of proteinuria in nephrotic syndrome due to extrarenal mechanisms. Autoantibodies identified in recent years are involved in the violation of the selective permeability of the filtration barrier in membranous nephropathy. The direct relationship between the level of hyperglycemia and proteinuria in diabetic nephropathy is analyzed. The role of reactive oxygen species, end products of glycation, angiotensin II, transforming growth factor β-1, epithelial-mesenchymal transformation of podocytes, Rho GTPases, intracellular signaling pathway mTOR, Wnt/β-catenin signaling cascade is emphasized. Particular attention is paid to the problem of searching and identifying circulating permeability factors in the pathogenesis of idiopathic nephrotic syndrome in patients with minimal changes and focal segmental glomerulosclerosis: vascular permeability factor (VPF), vasodilator-stimulated phosphoprotein (VASP), soluble hemopexin (Hpx) receptor-receptor-receptor type (suPAR), cardiotropin-like cytokine-1 (CLCF-1) and anti-CD40 antibodies. It is noted that the role of such factors is not in doubt today, however, from the standpoint of evidence-based medicine, this role needs serious confirmation by specially formulated criteria.

Human Th17 cells produce a soluble mediator that increases podocyte motility via signaling pathways that mimic PAR-1 activation.

The specific pathogenesis of idiopathic nephrotic syndrome (NS) is poorly understood, and the role of immune mediators remains contentious. However, there is good evidence for the role of a circulating factor, and we recently postulated circulating proteases as candidate factors. Immunosuppressive therapy with glucocorticoids (GCs) and T cell inhibitors are widely used in the clinical treatment of NS. Given that T helper (CD4+) cells expressing IL-17A (so-called Th17 cells) have recently been reported to be resistant to GC treatment, and GC resistance remains a major challenge in the management of NS, we hypothesized that Th17 cells produce a circulating factor that is capable of signaling to the podocyte and inducing deleterious phenotypic changes. To test this, we generated human Th17 cells from healthy volunteers and added the supernatants from these T cell cultures to conditionally immortalized human podocytes in vitro. This demonstrated that podocytes treated with Th17 cell culture supernatant, as well as with patient disease plasma, showed significant stimulation of JNK and p38 MAPK pathways and an increase in motility, which was blocked using a JNK inhibitor. We have previously shown that nephrotic plasma elicits a podocyte response via protease-activated receptor-1 (PAR-1). Stimulation of PAR-1 in podocytes elicited the same signaling response as Th17 cell culture supernatant treatment. Equally, protease inhibitors with Th17 cell culture treatment blocked the signaling response. This was not replicated by the reagents added to Th17 cell cultures or by IL-17A. Hence, we conclude that an undefined soluble mediator produced by Th17 cells mimics the deleterious effect of PAR-1 activation in vitro. Given the association between pathogenic subsets of Th17 cells and GC resistance, these observations have potential therapeutic relevance for patients with NS.

Interleukin-7 stimulation inhibits nephrin activation and induces podocyte injury

The glomerular podocytes control filtration barrier permeability in the kidney, and their disturbance underlies the pathogenesis of idiopathic nephrotic syndrome (INS), a kidney disease that predominantly occurs in children. In this study, we found that the interleukin-7 receptor (IL-7R) was induced in the glomeruli of adriamycin (ADR)-induced mouse nephropathy, a rodent model of nephrotic syndrome. In addition, IL-7R was also induced by ADR in mouse podocytes cultured in vitro. Functionally, we discovered that IL-7R activation through the stimulation of recombinant IL-7 induced apoptosis of podocytes, and moreover, IL-7 stimulation inhibited nephrin activation and caused actin cytoskeleton disorganization, indicating that IL-7 stimulation induces podocyte injury. Furthermore, IL-7 stimulation impaired the filtration barrier function of podocyte monolayer. Together, these results identify IL-7 and its receptor IL-7R as potential regulators of podocyte function, which might offer a novel therapeutic target in the treatment of INS.

Antiproteinuric effect of an endothelin-1 receptor antagonist in puromycin aminonucleoside-induced nephrosis in rat.

BackgroundThe pathogenesis of idiopathic nephrotic syndrome (INS) remains unclear, although recent studies suggest endothelin 1 (ET-1) and CD80 of podocytes are involved. We investigated the potential of antagonist to ET-1 receptor type A (ETRA) as therapeutic agent through the suppression of CD80 in a rat model of INS.MethodsPuromycin aminonucleoside (PAN) was injected to Wister rats to induce proteinuria: some were treated with ETRA antagonist and others were treated with 0.5% methylcellulose. Blood and tissue samples were collected. Quantitative PCR was used to determine the expression of Toll-like receptor-3 (TLR-3), nuclear factor-κB (NF-κB), CD80, talin, ETRA, and ET-1 in the kidney. To confirm the level of CD80 protein expression, immunofluorescence staining and western blot analysis of the renal tissue were performed.ResultsAmount of proteinuria in the treatment group was significantly lower than the other groups. The same-day body weight, serum creatinine values, and blood pressure were not significantly different. ETRA antagonist restores podocyte foot process effacement as well as the aberrant expression of TLR-3, nuclear factor-κB (NF-κB), and CD80 in PAN-injured kidneys.ConclusionsThe ETRA antagonist may be promising drug for INS as it showed an antiproteinuric effect. Its action was considered to be through suppression of CD80 expression on podocytes.

NOX-mediated impairment of PDGF-induced DNA synthesis in peripheral blood lymphocytes of children with idiopathic nephrotic syndrome.

BackgroundCellular oxidative stress, inflammatory responses, and immunogenic events are involved in pathogenesis of idiopathic nephrotic syndrome (INS); however, the exact mechanism remains unknown. We examined NADPH oxidase (NOX) activity and platelet-derived growth factor (PDGF)-induced DNA synthesis in peripheral blood lymphocytes (PBL) of patients with INS.MethodsPBL from 15 patients with INS and 15 age- and gender-matched controls were isolated, and enzyme activities of NOX, catalase, and superoxide dismutase (SOD) were measured along with the assay of malondialdehyde levels and bromo-deoxyuridine incorporation. Protein expression of NOX-1 was measured using western blot analysis.ResultsPatients with INS had significantly (P<0.01) higher NOX activity and increased protein expression of NOX-1 in PBL as compared with controls. Catalase and SOD activities were markedly lower with lipid peroxide levels significantly (P<0.01) increased in patients with INS. Ex vivo DNA synthesis in PDGF-stimulated PBL was significantly (P<0.01) reduced in patients with INS; however, diphenyliodonium, an inhibitor of NOX, markedly corrected impairment in growth factor-induced BrdU incorporation.ConclusionsThese results show that NOX activation might have a role in regulation of lymphocytic activity in patients with INS through the impairment of PDGF mitogenic function and might contribute toward pathogenesis of nephrotic syndrome.

Extrarenal determinants of kidney filter function.

The kidney is an organ involved in cross talk with many human organs. The link between the immune system and the kidney has been studied in some detail, although data precisely elucidating their interaction are sparse, in particular with regard to the function of the kidney filter apparatus. Current research suggests that an understanding of the impairment of this cross talk between the bone marrow, as a fundament of the immune system and the kidney will provide meaningful insights into the pathophysiological mechanisms of impaired kidney filter function. Circulating factors have long been implicated in the pathogenesis of idiopathic nephrotic syndrome, particularly focal segmental glomerulosclerosis (FSGS) and its recurrence. Soluble urokinase receptor (suPAR) has emerged as a circulating factor responsible for FSGS and also as an early predictive marker for the development of various renal diseases. The bone marrow has recently been revealed as a predominant source of suPAR with deleterious effects on the kidney filter. These new findings have led to bone marrow or hematopoietic stem cell transplants being considered as potential therapeutic options for preventing the post-transplantation recurrence of FSGS or even as a treatment for the original disease associated with high suPAR levels. Whereas bone marrow transplantation for patients with pre-existing chronic kidney disease is challenging, recent clinical trials have demonstrated the promising outcome of combined bone marrow and kidney transplantation in patients with kidney failure. In this review, with its brief update on suPAR, we describe the critical new role of the bone marrow in the pathogenesis of the kidney disease process and the functional connection between these two organs through the soluble mediator, suPAR. We also comment on the feasibility of bone marrow transplants for the treatment of patients with chronic renal failure arising from recurrent FSGS.

Regulatory T cells and CTLA-4 in idiopathic nephrotic syndrome.

The pathogenesis of idiopathic nephrotic syndrome (INS) remains unknown. Recently, it was postulated that suppression of regulatory T cells (Treg) leads to massive proteinuria in INS, although there is some controversy. Considering the important role of cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) in Treg-mediated immune suppression, the aim of this study was therefore to clarify the involvement of Treg and CTLA-4 in the pathogenesis of INS. Fifteen patients with INS were enrolled. Their blood was sampled twice, once at onset and once at remission induced by glucocorticoid. Although median Treg number was significantly lower at onset than in healthy children, it increased at remission. Similarly, serum CTLA-4 concentration significantly increased at remission compared with onset. Furthermore, a positive significant correlation was observed between Treg number and serum CTLA-4 level. This suggests that Treg and CTLA-4 are involved in the induction of remission in INS.

Immunology of idiopathic nephrotic syndrome.

The pathogenesis of idiopathic nephrotic syndrome (INS) is as yet unknown, but several lines of evidence indicate that the immune system may play a crucial pathogenic role in non-genetic INS. The most important of these are, first, the effectiveness of therapy based on immunosuppression and, second, a vast body of data derived both from experimental models and from patient studies that implicate T cells and more recently B cells as major players in INS pathogenesis. However, recent findings also suggest a direct role of podocytes as drivers of the disease process, and the interplay between the glomerulus and the immune system is still being elucidated. In this review we provide an overview of current knowledge on the role of different components of the immune system in determining disease. Advances in our understanding of the pathogenesis of INS may help drive new, more tailored therapeutic approaches.