NEPHRUTIX: A randomized, double-blind, placebo vs Rituximab-controlled trial assessing T-cell subset changes in Minimal Change Nephrotic Syndrome.

Minimal-change nephrotic syndrome (MCNS) is an immune-mediated glomerular disease. We have analyzed the modifications on T-cell subsets in twenty-three patients who were highly steroid/calcineurin inhibitor and/or mycophenolate mofetil-dependent for frequently relapsing nephrotic syndrome (FRNS) and who were enrolled in a multicenter, double-blind, randomized, placebo vs Rituximab-controlled trial. Patients with FRNS entered the trial at remission and were randomly assigned to receive either Rituximab or placebo. In both groups, patient blood samples were analyzed at inclusion and then monthly until six months post-perfusion. Disclosure of patient's allocation code occurred in relapse or at the end of the trial. All patients under placebo displaying relapse were subsequently treated with Rituximab. Despite the significant decrease of immunosuppressive drugs, remission was maintained in all patients included in the Rituximab group, except one (n = 9/10). On the other hand, relapses occurred within a few weeks (means ≈ 7.3 weeks) in all patients receiving placebo (n = 13). At inclusion, before rituximab therapy, the frequency of different T-cell subsets were highly similar in both groups, except for CD8+ and invariant TCRVα24 T-cell subsets, which were significantly increased in patients of the Placebo group ((p = 0,0414 and p = 0.0428, respectively). Despite the significant decrease of immunosuppressive drugs, remission was maintained in all patients included in the Rituximab group (n = 10), except one. Relapses were associated with a significant decrease in CD4+CD25highFoxP3high Tregulatory cells (p = 0.0005) and IL2 expression (p = 0.0032), while CMIP abundance was significantly increased (p = 0.03). Remissions after Rituximab therapy were associated in both groups with significant decrease in the frequency of CD4+CD45RO+CXCR5+, invariant natural killer T-cells (INKT) and CD4-CD8- (double-negative, DN) T-cells expressing the invariant Vα24 chain (DN-TCR Vα24) T-cells, suggesting that MCNS involves a disorder of innate and adaptive immune response, which can be stabilized by Rituximab treatment.

Nephrotic Syndrome in Small Cell Lung Cancer and Induction of C-Mip in Podocytes.

Paraneoplastic nephrotic syndrome is often a complication in patients with cancer, and various histologic lesions have been described in the kidney. We report the case of a 76-year-old woman who presented with a podocytopathy that was found to be associated with a small cell lung carcinoma (SCLC). One cycle of carboplatin-etoposide combination therapy led to resolution of nephrotic syndrome and remission of the lung carcinoma. C-Maf-inducing protein (C-Mip) was overexpressed in both podocytes and cancer cells, but was not found in control kidney and lung tissue samples. C-Mip also was absent in SCLC cells from 30 patients without nephrotic syndrome. Exposing cultured podocytes to a sample of our patient's serum that was collected prior to chemotherapy led to disorganization of the podocyte cytoskeleton and induction of C-Mip expression, which was not observed with control serum or our patient's serum sampled after chemotherapy. These observations suggest that C-Mip may play an important role in SCLC-related podocytopathy and that a circulating factor likely induces its expression in the kidney.

Repression of CMIP transcription by WT1 is relevant to podocyte health.

The WT1 (Wilm's tumor suppressor) gene is expressed throughout life in podocytes and is essential for the functional integrity of the glomerular filtration barrier. We have previously shown that CMIP (C-Maf inducing protein) is overproduced in podocyte diseases and alters intracellular signaling. Here we isolated the proximal region of the human CMIP promoter and showed by chromatin immunoprecipitation assays and electrophoretic-mobility shift that Wilm's tumor protein (WT1) bound to 2 WT1 response elements, located at positions -290/-274 and -57/-41 relative to transcription start site. Unlike the human CMIP gene, only one Wt1 response element was identified in the mouse Cmip proximal promoter located at position -217/-206. Luciferase reporter assays indicated that WT1 dose-dependently inhibited the transcriptional induction of the CMIP promoter. Transfection of decoy oligonucleotides mimicking the WT1 response elements prevented the inhibition of WT1 on CMIP promoter activity. Furthermore, WT1 silencing promoted Cmip expression. In line with these findings, the abundance of Cmip was early and significantly increased at the transcript and protein level in podocytes displaying a primary defect in Wt1, including Denys-Drash syndrome and Frasier syndrome. Thus, WT1 is a major repressor of the CMIP gene in physiological situations, while conditional deletion of CMIP in the developing kidney did not affect the development of mature glomeruli.

Inhibition of the VEGF signalling pathway and glomerular disorders.

Anti-cancer therapeutic approaches targeting the vascular endothelial growth factor (VEGF) ligand (anti-VEGF) or inhibiting its receptors (RTKI) have recently been developed. In spite of the promising results achieved, a serious drawback and dose-limiting side effect is the development, among others, of renal complications. This encompasses two glomerular pathological entities, namely minimal change/focal segmental glomerulosclerosis and thrombotic micro-angiopathy, involving two distinct cell types, podocytes and endothelial cells, respectively. The mechanisms that link anti-cancer therapy by RTKI to podocyte dysfunction and nephrotic level proteinuria are still poorly understood. Nevertheless, recent findings strongly suggest a central role of RelA, the master subunit of NF-κB and c-mip, an active player in podocyte disorders. RelA, which is up-regulated following anti-VEGF therapy, is inactivated by RTKI, leading to c-mip over-expression in the podocyte. This results in severe alterations in the architecture of podocyte actin cytoskeleton and subsequent severe proteinuria. Hence, clarifying the mechanisms linking c-mip and RelA as key pathogenic factors represents a critical goal in the understanding of different glomerulopathies. In the context of VEGF-targeted anti-cancer therapy, the study of these mechanisms along with the molecular cross-talk between podocyte and endothelial cell constitutes the basis for the emerging field of onconephrology.

Expression patterns of RelA and c-mip are associated with different glomerular diseases following anti-VEGF therapy.

Renal toxicity constitutes a dose-limiting side effect of anticancer therapies targeting vascular endothelial growth factor (VEGF). In order to study this further, we followed up 29 patients receiving this treatment, who experienced proteinuria, hypertension, and/or renal insufficiency. Eight developed minimal change nephropathy/focal segmental glomerulopathy (MCN/FSG)-like lesions and 13 developed thrombotic microangiopathy (TMA). Patients receiving receptor tyrosine kinase inhibitors (RTKIs) mainly developed MCN/FSG-like lesions, whereas TMA complicated anti-VEGF therapy. There were no mutations in factor H, factor I, or membrane cofactor protein of the complement alternative pathway, while plasma ADAMTS13 activity persisted and anti-ADAMTS13 antibodies were undetectable in patients with TMA. Glomerular VEGF expression was undetectable in TMA and decreased in MCN/FSG. Glomeruli from patients with TMA displayed a high abundance of RelA in endothelial cells and in the podocyte nuclei, but c-mip was not detected. Conversely, MCN/FSG-like lesions exhibited a high abundance of c-mip, whereas RelA was scarcely detected. RelA binds in vivo to the c-mip promoter and prevents its transcriptional activation, whereas RelA knockdown releases c-mip activation. The RTKI sorafenib inhibited RelA activity, which then promoted c-mip expression. Thus, our results suggest that c-mip and RelA define two distinct types of renal damage associated with VEGF-targeted therapies.

Upregulation of c-mip is closely related to podocyte dysfunction in membranous nephropathy.

Membranous nephropathy is a glomerular disease typified by a nephrotic syndrome without infiltration of inflammatory cells or proliferation of resident cells. Although the cause of the disease is unknown, the primary pathology involves the generation of autoantibodies against antigen targets on the surface of podocytes. The mechanisms of nephrotic proteinuria, which reflect a profound podocyte dysfunction, remain unclear. We previously found a new gene, c-mip (c-maf-inducing protein), that was associated with the pathophysiology of idiopathic nephrotic syndrome. Here we found that c-mip was not detected in the glomeruli of rats with passive-type Heymann nephritis given a single dose of anti-megalin polyclonal antibody, yet immune complexes were readily present, but without triggering of proteinuria. Rats reinjected with anti-megalin develop heavy proteinuria a few days later, concomitant with c-mip overproduction in podocytes. This overexpression was associated with the downregulation of synaptopodin in patients with membranous nephropathy, rats with passive Heymann nephritis, and c-mip transgenic mice, while the abundance of death-associated protein kinase and integrin-linked kinase was increased. Cyclosporine treatment significantly reduced proteinuria in rats with passive Heymann nephritis, concomitant with downregulation of c-mip in podocytes. Thus, c-mip has an active role in the podocyte disorders of membranous nephropathy.

c-mip down-regulates NF-κB activity and promotes apoptosis in podocytes.

The mechanisms of podocyte disorders in cases of idiopathic nephrotic syndrome (INS) are complex and remain incompletely elucidated. The abnormal regulation of NF-κB may play a key role in the pathophysiology of these podocyte diseases, but at present, NF-κB has not been thoroughly investigated. In this study, we report that induction of c-mip in podocytes of patients with INS is associated with a down-regulation of RelA, a potent antiapoptotic factor that belongs to the NF-κB family. Overexpression of c-mip in differentiated podocytes promotes apoptosis by inducing caspase-3 activity and up-regulating the proapoptotic protein Bax, whereas the overall levels of the antiapoptotic protein Bcl-2 was concomitantly decreased. The associated overexpression of RelA prevented the proapoptotic effects of c-mip. In addition, the targeted induction of c-mip in podocytes in vivo inhibited the expression of the RelA protein and increased the Bax/Bcl-2 ratio. The expression of both c-mip and active caspase-3 increased in focal and segmental glomerulosclerosis biopsies, and both proteins displayed a close spatial relationship. These results suggest that alterations in NF-κB activity might result from the up-regulation of c-mip and are likely to contribute to podocyte disorders in cases of INS.

Occurrence of minimal change nephrotic syndrome in classical Hodgkin lymphoma is closely related to the induction of c-mip in Hodgkin-Reed Sternberg cells and podocytes.

It is currently considered that idiopathic minimal change nephrotic syndrome is an immune-mediated glomerular disease. Its association with classical Hodgkin lymphoma minimal change nephrotic syndrome (cHL-MCNS) suggests a molecular link, which remains to be elucidated. We analyzed the expression of cmaf inducing protein (c-mip) in lymphomatous tissues and kidney biopsy samples of patients with cHL-MCNS (n = 8) and in lymphomatous tissues of patients with isolated cHL (n = 9). Because c-mip affects the regulatory loop involving Fyn, we investigated possible structural defects in this signaling pathway, using laser capture microdissection, reverse transcription polymerase chain reaction, and Western blotting. We found that c-mip was selectively expressed in Hodgkin and Reed-Sternberg (HRS) cells and podocytes of patients with cHL-MCNS but is undetectable in patients with isolated cHL. We demonstrated that c-mip was specifically involved in the negative regulation of early proximal signaling through its interaction with phosphoprotein associated with glycosphingolipid-enriched microdomains and Fyn. We showed that the up-regulation of c-mip in cHL-MCNS was associated with a possible Fyn defect in HRS cells and podocytes. Moreover, we showed that c-mip was up-regulated in Fyn-deficient podocytes. c-mip may be a useful marker of cHL-MCNS and its induction reflects the dysregulation of proximal signaling.

Truncation of C-mip (Tc-mip), a new proximal signaling protein, induces c-maf Th2 transcription factor and cytoskeleton reorganization.

Several arguments suggest that minimal change nephrotic syndrome (MCNS) results from yet unknown systemic disorder of T cell function. By screening a cDNA library from T cell relapse, we identified a new pleckstrin homology (PH) domain-containing protein encoded by a gene located on chromosome 16q24. Two alternative transcripts were identified. The first species (c-mip) was expressed in fetal liver, kidney, and peripheral blood mononuclear cells (PBMCs), but weakly detected in PBMCs from MCNS patients. The second form (Tc-mip, standing for truncated c-maf inducing protein), corresponds to subtracted transcript and lacks the NH2-terminal PH domain. The expression of Tc-mip was restricted to fetal liver, thymus, and MCNS PBMCs where it was specifically recruited in CD4+ T cells subset. Overexpression of Tc-mip in T cell Jurkat induced c-maf, transactivated the interleukin 4 gene and down-regulated the interferon gamma expression, characteristic of a Th2 commitment. Moreover, the overexpression of Tc-mip induced Src phosphorylation, T cell clustering, and a cellular redistribution of the cytoskeleton-associated L-plastin, by a PI3 kinase independent pathway. Tc-mip represents therefore the first identified protein, which links proximal signaling to c-maf induction.

C-mip interacts physically with RelA and inhibits nuclear factor kappa B activity.

The fine regulation of NF-kappaB activity is crucial for both resting and stimulated cells and relies on complex balance between multiple activators and inhibitors. We report here that c-mip, a recently identified pleckstrin homology (PH) and leucine-rich repeat (LRR)-domain-containing protein, inactivates GSKbeta and interacts with RelA, a key member of the NF-kappaB family. We show that c-mip inhibits the degradation of I-kappaBalpha and impedes the dissociation of the NF-kappaB/I-kappaBalpha complexes. C-mip acts downstream signaling of classical NF-kappaB pathway and may represent one of the missing links in the control of NF-kappaB activity.

Potential role of soluble ST2 protein in idiopathic nephrotic syndrome recurrence following kidney transplantation.

BACKGROUND: Corticosteroid-resistant idiopathic nephrotic syndrome (INS) recurs rapidly after transplantation in 30% to 50% of transplant recipients, suggesting the presence of 1 or more circulating factors that alter the glomerular filtration barrier. We investigated the possible role in INS recurrence of soluble ST2 (sST2) protein, a marker of T helper type 2 (T(H)2) cells and a factor predicted to be regulated by the transcription factor c-Maf; involvement of sST2 protein would be consistent with the observation that both T(H)2 cells and c-Maf appear to be activated during INS relapse. STUDY DESIGN: Retrospective observational study. SETTING & PARTICIPANTS: Patients with biopsy-proven corticosteroid-resistant INS who had undergone kidney transplantation between September 1983 and April 2007 (n = 71). A control group consisting of proteinuric transplant recipients with kidney failure unrelated to INS (n = 34). PREDICTOR: Patients who developed INS recurrence after transplantation (n = 31) were compared with those in whom INS did not recur (n = 40) and the control group. Recurrence of INS was defined as urine protein excretion greater than 2 g/d immediately after transplantation that persisted at greater than 1 g/d despite treatment or a kidney graft biopsy showing minimal change glomerulonephritis or focal segmental glomerulosclerosis. OUTCOMES & MEASUREMENTS: Urine protein excretion in the 3 groups was 5.0 g/d (range, 1.3 to 10.5), 0.14 g/d (range, 0 to 0.46), and 4.3 g/d (range, 3 to 6.2). The sST2 protein was analyzed both quantitatively and qualitatively in patient sera, and its activity was tested in vitro on a mouse podocyte cell line and in vivo in rats. RESULTS: sST2 protein levels were significantly increased after transplantation in patients with INS recurrence compared with the 2 other groups (617.5 versus 23 pg/mL; P < 0.001 and 158.5 pg/mL; P < 0.01 respectively). However, patients with recurrence expressed a normal sST2 isoform, and the sST2 protein was unable to induce podocyte injury in vitro or trigger proteinuria in rats. LIMITATIONS: Pretransplantation and posttransplantation sera do not always represent paired samples. CONCLUSIONS: These data suggest that sST2 protein is a marker of INS recurrence that does not seem to be involved in the development of INS.

Expression of CMIP in podocytes is restricted to specific classes of lupus nephritis.

Lupus glomerulopathies are classified into various histological patterns, which probably result from different pathophysiological origins. Podocyte injury can be demonstrated in lupus nephritis but its clinical relevance is far little appreciated and is often masked by proliferative lesions and inflammatory cell infiltrations. Two patterns of podocyte lesions may be considered, either occurring in the context of renal inflammation or reflecting podocyte dysfunction in non-proliferative and non-inflammatory glomerulopathies. This distinction remains elusive since no reliable biomarker discriminates between both entities. CMIP was recently found induced in some glomerular disease but its expression in different lupus nephritis classes has not been investigated. Twenty-four adult patients with lupus nephritis, including non-proliferative (n = 11) and proliferative (n = 13) glomerulopathies were analyzed. Clinical, biological and immunological data were compared with immunomorphological findings. We analyzed by quantitative and qualitative methods the expression of CMIP in different histological classes. We found CMIP abundance selectively increased in podocytes in class II and class V glomerulopathies, while in proliferative forms (class III and class IV), CMIP was rarely detected. CMIP was not expressed in cellular crescents, endothelial cells or mesangial cells. CMIP colocalized with some subsets of B and T cells within glomerular or interstitial mononuclear cell infiltrates but never with macrophages. Hematuria is rarely present in lupus glomerulopathies expressing CMIP. There was no correlation between classical immunological markers and CMIP expression. Thus, CMIP induction in lupus nephritis seems restricted to non-proliferative glomerulopathies and may define a specific pattern of podocyte injury.

A 59-kD renal antigen as a new target for rapidly progressive glomerulonephritis.

Anti-glomerular basement membrane (anti-GBM) antibodies are the hallmark of anti-GBM disease, which is characterized by rapidly progressive glomerulonephritis. We describe the case of a 58-year-old woman who presented with rapidly progressive glomerulonephritis with typical anti-GBM staining found by means of direct immunofluorescence microscopy, associated with linear immunoglobin G deposits on tubules. Serum analysis showed circulating anti-tubular basement membrane antibodies, but failed to detect anti-GBM antibodies. Immunoblotting showed that serum antibodies reacted with a 59-kd antigen found along both the GBM and tubular basement membrane.

The Filamin-A is a partner of Tc-mip, a new adapter protein involved in c-maf-dependent Th2 signaling pathway.

Using a yeast two-hybrid screen, we identified Filamin-A as a binding partner of the new adapter protein c-mip (c-maf inducing protein) and it's splice variant Tc-mip (truncated c-maf inducing protein). We have previously shown that Tc-mip is involved in Th2 signaling pathway and cytoskeletal reorganization in patients with minimal change nephrotic syndrome (MCNS), the most frequent glomerular disease in children. We showed that Filamin-A and c-mip or Tc-mip co-immunoprecipitate from c-mip or Tc-mip Jurkat transfected cells using antibodies directed against both types of proteins. In co-immunoprecipitate Jurkat cells, Filamin-A and c-mip were distributed evenly in the cytoplasm, whereas in Tc-mip-transfected Jurkat cells, Filamin-A was expressed in zones facing the cell contact. Moreover, we found that Filamin-A was upregulated in T lymphocytes of MCNS patients, as compared to normal subjects. These findings suggest that Filamin-A interacts with c-mip/Tc-mip in this new T-cell signaling pathway.

[New insights about immunopathology of lipoid nephrosis]. / Immunopathologie de la néphrose lipoïdique. Données récentes.

Clinical and experimental observations suggest that Lipoid Nephrosis (Minimal change nephrotic syndrome) results from T cell dysfunction due to still unknown mechanisms. By subtractive screening library, we identified 84 transcripts, of which twelve match with proteins of yet unknown function and thirty are unknown clones. Among the 42 known transcripts, at least 18 are closely involved in the TCR-mediated complex signaling cascade. This includes genes encoding components of the T cell receptor and proteins associated with the cytoskeleton scaffold, as well as transcription factors such as NF-kappa B and c-maf. During the relapse phase, we have found significant alterations of the NF-kappa B/I kappa Ba regulatory pathway, whereas very low levels of IL12R beta 2 mRNA were detected suggesting that T cell activation evolves toward a Th2 phenotype. We have shown that c-maf is highly induced, shuttling between nuclear and cytoplasmic compartment during the relapse and the remission phases, respectively. Contrasting with the nuclear expression of c-maf, low IL4 levels were detected in relapse. This suggests that the downstream target gene of c-maf in Lipoid Nephrosis, is not IL4 and provides new directions in research leading to identify the target gene, possibly an unknown Th2 cytokine, which might play a critical role in the pathophysiology of this disease. Thus, the combination of subtractive cloning and differential screening constitutes an efficient approach to identify genes likely to be involved in the pathophysiology of MCNS.

Immunopathogenesis of idiopathic nephrotic syndrome with relapse.

Idiopathic change nephrotic syndrome (INS), the most frequent glomerular disease in children and young adults, is characterized by heavy proteinuria and a relapsing remitting course. Although the mechanisms underlying the pathophysiology of proteinuria remain unclear, clinical and experimental observations suggest that lymphocyte and podocyte disturbances are two sides of the disease. The current hypothesis suggests that immune cells release a putative factor, which alters podocyte function resulting in nephrotic proteinuria. Besides T-cell abnormalities, recent evidence of B-cell depletion efficacy in sustained remissions added a new challenge in understanding the immunological mechanisms of INS. In this review, we discuss recent insights related to podocyte disorders occurring in INS and their relevance in human diseases.

Kidney diseases associated with anti-vascular endothelial growth factor (VEGF): an 8-year observational study at a single center.

Expanded clinical experience with patients taking antiangiogenic compounds has come with increasing recognition of the renal adverse effects. Because renal histology is rarely sought in those patients, the renal consequences are underestimated. Antiangiogenic-treated-cancer patients, who had a renal biopsy for renal adverse effects from 2006 to 2013, were included in the current study. Clinical features and renal histologic findings were reviewed. Our cohort was 100 patients (58 women) with biopsy-proven kidney disease using anti-vascular endothelial growth factor (VEGF) therapy with a mean age of 59.8 years (range, 20-85 yr). Patients were referred for proteinuria, hypertension, and/or renal insufficiency. Kidney biopsy was performed 6.87 ±â€Š7.18 months after the beginning of treatment. Seventy-three patients experienced renal thrombotic microangiopathy (TMA) and 27 patients had variable glomerulopathies, mainly minimal change disease and/or collapsing-like focal segmental glomerulosclerosis (MCN/cFSGS). MCN/cFSGS-like lesions developed mainly with tyrosine-kinase inhibitors, whereas TMA complicated anti-VEGF ligand. Thirty-one percent of TMA patients had proteinuria up to 1 g/24 h. Half of TMA cases are exclusively renal localized. Pathologic TMA features are intraglomerular exclusively. MCN/cFSGS glomeruli displayed a high abundance of KI-67, but synaptopodin was not detected. Conversely, TMA glomeruli exhibited a normal abundance of synaptopodin-like control, whereas KI-67 was absent. Median follow-up was 12 months (range, 1-80 mo). Fifty-four patients died due to cancer progression. Hypertension and proteinuria resolved following drug discontinuation and antihypertensive agents. No patient developed severe renal failure requiring dialysis. Drug continuation or reintroduction resulted in a more severe recurrence of TMA in 3 out of 4 patients requiring maintenance of anti-VEGF agents despite renal TMA. In conclusion, TMA and MCN/cFSGS are the most frequent forms of renal involvement under anti-VEGF therapy. Careful risk-benefit assessment for individual patients should take into account risk factors related to the host and the tumor.

Minimal change nephrotic syndrome associated with non-Hodgkin lymphoid disorders: a retrospective study of 18 cases.

Few studies have examined the occurrence of minimal change nephrotic syndrome (MCNS) in patients with non-Hodgkin lymphoma (NHL). We report here a series of 18 patients with MCNS occurring among 13,992 new cases of NHL. We analyzed the clinical and pathologic characteristics of this association, along with the response of patients to treatment, to determine if this association relies on a particular disorder. The most frequent NHLs associated with MCNS were Waldenström macroglobulinemia (33.3%), marginal zone B-cell lymphoma (27.8%), and chronic lymphocytic leukemia (22.2%). Other lymphoproliferative disorders included multiple myeloma, mantle cell lymphoma, and peripheral T-cell lymphoma. In 4 patients MCNS occurred before NHL (mean delay, 15 mo), in 10 patients the disorders occurred simultaneously, and in 4 patients MCNS was diagnosed after NHL (mean delay, 25 mo). Circulating monoclonal immunoglobulins were present in 11 patients. A nontumoral interstitial infiltrate was present in renal biopsy specimens from 3 patients without significant renal impairment. Acute kidney injury resulting from tubular lesions or renal hypoperfusion was present in 6 patients. MCNS relapse occurred more frequently in patients treated exclusively by steroid therapy (77.8%) than in those receiving steroids associated with chemotherapy (25%). In conclusion, MCNS occurs preferentially in NHL originating from B cells and requires an aggressive therapeutic approach to reduce the risk of MCNS relapse.

Upregulation of nuclear factor-related kappa B suggests a disorder of transcriptional regulation in minimal change nephrotic syndrome.

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.

Immunopathogenesis of idiopathic nephrotic syndrome.

Idiopathic nephrotic syndrome is the most frequent glomerular disease in children. The mechanisms underlying its pathophysiology have been investigated by genetic, cellular and molecular approaches. While genetic analyses have provided new insights into disease pathogenesis through the discovery of several podocyte genes mutated in distinct forms of inherited nephrotic syndrome, the molecular bases of minimal change nephrotic syndrome and focal and segmental glomerulosclerosis with relapse remain unclear. The immune system seems to play a critical role in the active phase of this disease through disturbances involving several cell subsets, mainly T cells. The innate immune system may also contribute to the immune disorders. In this review, we discuss recent insights from the molecular and immunological findings and their significance in the context of the clinical course of the disease.