Immunopathological findings in idiopathic nephrosis: clinical significance of glomerular "immune deposits"

To biopsy or not to biopsy a teenager with idiopathic nephrotic syndrome? Biopsy first

Kidney biopsy plays a crucial role in the diagnosis and management of several glomerular diseases. While it is generally considered a routine and safe procedure in children, it should be conducted with the primary objective of addressing the following question: do the prognosis and treatments vary based on the findings of kidney biopsy? In children presenting with idiopathic nephrotic syndrome (INS), guidelines suggest to consider kidney biopsy for individuals older than 12 years, primarily due to the possible increased incidence of different glomerulonephritis compared to younger patients, who predominantly manifest with minimal change disease. However, these guidelines also advocate for uniform therapeutic strategies, typically steroids, irrespective of the age or histological findings. Whether the age of more than 12 years may be a recommendation for performing kidney biopsy at presentation of INS is debatable. Instead, kidney biopsy could be reserved for steroid-resistant cases. On the other hand, when kidney biopsy is performed in INS, particularly in focal segmental glomerulosclerosis, histology may reveal additional lesions, that are strongly associated with a poorer response to treatment and worse clinical outcomes. Therefore, current guidelines on treatments of nephrotic syndrome may appear overly restrictive, despite the relevant findings provided by kidney biopsy. Therefore, in the present manuscript, which is part of a pro-con debate on the management of nephrotic syndrome in adolescents, we emphasize the potential role of performing a kidney biopsy before initiating corticosteroid treatment.

Current understanding of the molecular mechanisms of circulating permeability factor in focal segmental glomerulosclerosis

The pathogenetic mechanisms underlying the onset and the post-transplant recurrence of primary focal segmental glomerulosclerosis (FSGS) are complex and remain yet to be fully elucidated. However, a growing body of evidence emphasizes the pivotal role of the immune system in both initiating and perpetuating the disease. Extensive investigations, encompassing both experimental models and patient studies, have implicated T cells, B cells, and complement as crucial actors in the pathogenesis of primary FSGS, with various molecules being proposed as potential "circulating factors" contributing to the disease and its recurrence post kidney-transplantation. In this review, we critically assessed the existing literature to identify essential pathways for a comprehensive characterization of the pathogenesis of FSGS. Recent discoveries have shed further light on the intricate interplay between these mechanisms. We present an overview of the current understanding of the engagement of distinct molecules and immune cells in FSGS pathogenesis while highlighting critical knowledge gaps that require attention. A thorough characterization of these intricate immune mechanisms holds the potential to identify noninvasive biomarkers that can accurately identify patients at high risk of post-transplant recurrence. Such knowledge can pave the way for the development of targeted and personalized therapeutic approaches in the management of FSGS.

Comparison of dominant and nondominant C3 deposition in primary glomerulonephritis

BACKGROUND

Alternative complement pathway dysregulation plays a key role in glomerulonephritis (GN) and is associated with C3 deposition. Herein, we examined pathological and clinical differences between cases of primary GN with C3-dominant (C3D-GN) and nondominant (C3ND-GN) deposition.

METHODS

We extracted primary GN data from the Korean GlomeruloNEphritis sTudy (KoGNET). C3D-GN was defined as C3 staining two grades greater than C1q, C4, and immunoglobulin via immunofluorescence analysis. To overcome a large difference in the number of patients between the C3D-GN and C3ND-GN groups (31 vs. 9,689), permutation testing was used for analysis.

RESULTS

The C3D-GN group exhibited higher serum creatinine (p ≤ 0.001), a greater prevalence of estimated glomerular filtration rate of <60 mL/min/1.72 m2 (p ≤ 0.001), higher (but not significantly so) C-reactive protein level, and lower serum C3 level (p ≤ 0.001). Serum albumin, urine protein/creatinine ratio, number of patients who progressed to end-stage renal disease, and all-cause mortality were comparable between groups. Interstitial fibrosis and mesangial cellularity were greater in the C3D-GN group (p = 0.04 and p = 0.01, respectively) than in the C3ND-GN group. C3 deposition was dominant in the former group (p < 0.001), in parallel with increased subendothelial deposition (p ≤ 0.001).

CONCLUSION

Greater progression of renal injury and higher mortality occurred in patients with C3D-GN than with C3ND-GN, along with pathologic differences in interstitial and mesangial changes.

The Immune System and Idiopathic Nephrotic Syndrome

Idiopathic nephrotic syndrome often responds to immunosuppressive treatment. Nevertheless, this syndrome-and the drugs used to treat it-remain important causes of patient morbidity. Idiopathic nephrotic syndrome is usually caused by minimal change disease or FSGS, diseases that primarily affect the podocytes. In spite of decades of research, the underlying causes of both diseases remain incompletely understood. There is, however, a large body of observational and experimental data linking the immune system with both minimal change disease and FSGS, including associations with systemic infections and hematologic malignancies. Perhaps most compellingly, many different immunomodulatory drugs are effective for treating idiopathic nephrotic syndrome, including biologic agents that have well-defined immune targets. In fact, the unexpected efficacy of targeted therapeutic agents has provided important new insights into the pathogenesis of these diseases. Given the large number of drugs that are available to deplete or block specific cells and molecules within the immune system, a better understanding of the immunologic causes of idiopathic nephrotic syndrome may lead to better diagnostic and therapeutic approaches.

Efficacy of rituximab therapy in children with nephrotic syndrome: a 10-year experience from an Iranian pediatric hospital

Background

There are controversy results in the optimal management of children with steroid-dependent and steroid-resistant nephrotic syndrome (SDNS, SRNS). This study aimed to determine the efficacy and safety of rituximab (RTX) in these pediatric patients.

Methods

Medical records of 1–18-year-old Iranian children with SDNS (n = 26) and SRNS (n = 22) with a follow-up for at least 24 months were included from 2009 to 2019. The short- and long-term responses to RTX were respectively evaluated to determine the random protein-to-creatinine ratio after 6 and 24 months and classified as complete (CR) and partial (PR) remission or no response.

Results

Male patients (n = 26) were slightly predominate. The median age of patients at the time of RTX therapy was 8.6 ± 4.01 years. At the end of the 6-month follow-up, CR and PR occurred in 23 (47.9%) and 12 (25%) patients, respectively. Of 23 patients with CR, 18 (69.2%) and 5(22.7%) had SDNS and SRNS, respectively (p < 0.005). However, only 18 (37.5%) of patients after 24 months had been in CR. No significant difference in the CR rate was found between the two groups. RTX was more effective when administered during the proteinuria-free period (p = 0.001).

Conclusion

In the short term, RTX significantly was efficient in inducing complete or PR in SDNS and SRNS patients. However, the favorable response rate in a long-term follow-up was insignificantly lower between the two groups.

Natural antibody and complement activation characterize patients with idiopathic nephrotic syndrome

Focal segmental glomerulosclerosis (FSGS) and minimal change disease (MCD) are common forms of idiopathic nephrotic syndrome. The causes of these diseases are incompletely understood, but the response of patients to immunosuppressive therapies suggests that their pathogenesis is at least in part immune mediated. Preclinical and clinical research indicates that activation of the classical pathway of complement contributes to glomerular injury in FSGS. Glomerular IgM deposits are also prominent in some patients, raising the possibility that IgM is a trigger of classical pathway activation. In the present study, we examined the pattern of complement activation in the glomeruli and plasma of patients with nephrotic syndrome. We also tested whether patients with FSGS and MCD have elevated levels of natural IgM reactive with epitopes on glomerular endothelial cells and cardiolipin. We found evidence of classical pathway activation in patients with idiopathic nephrotic syndrome compared with healthy control subjects. We also detected higher levels of self-reactive IgM to both targets. Based on these results, IgM and classical pathway activation may contribute to disease pathogenesis in some patients with FSGS and MCD.NEW & NOTEWORTHY IgM is detected in biopsies from some patients with nephrotic syndrome, although this has been attributed to passive trapping of the protein. We found, however, that IgM colocalizes with complement activation fragments in some glomeruli. We also found that affected patients had higher levels of IgM reactive to glomerular endothelial cell epitopes. Thus, IgM activates the complement system in the glomeruli of some patients with nephrotic syndrome and may contribute to injury.

Renal Outcome of IgM Nephropathy: A Comparative Prospective Cohort Study

Immunoglobulin M nephropathy (IgMN) is an idiopathic glomerulonephritis characterized by diffuse deposits of IgM in the glomerular mesangium. However, its renal prognosis remains unknown. We compared renal outcomes of IgMN patients with those of patients with minimal change disease (MCD), focal segmental glomerulosclerosis (FSGS), or mesangial proliferative glomerulonephritis (MsPGN) from a prospective observational cohort, with 1791 patients undergoing native kidney biopsy in eight hospitals affiliated with The Catholic University of Korea between December 2014 and October 2020. IgMN had more mesangial proliferation and matrix expansion than MsPGN and more tubular atrophy and interstitial fibrosis than MCD. IgMN patients had decreased eGFR than MCD patients in the earlier follow-up. However, there was no significant difference in urine protein or eGFR among all patients at the last follow-up. When IgMN was divided into three subtypes, patients with FSGS-like IgMN tended to have lower eGFR than those with MCD-like or MsPGN-like IgMN but higher proteinuria than MsPGN-like IgMN without showing a significant difference. The presence of hypertension at the time of kidney biopsy predicted ≥20% decline of eGFR over two years in IgMN patients. Our data indicate that IgMN would have a clinical course and renal prognosis similar to MCD, FSGS, and MsPGN.

Loss of decay-accelerating factor triggers podocyte injury and glomerulosclerosis

Kidney glomerulosclerosis commonly progresses to end-stage kidney failure, but pathogenic mechanisms are still poorly understood. Here, we show that podocyte expression of decay-accelerating factor (DAF/CD55), a complement C3 convertase regulator, crucially controls disease in murine models of adriamycin (ADR)-induced focal and segmental glomerulosclerosis (FSGS) and streptozotocin (STZ)-induced diabetic glomerulosclerosis. ADR induces enzymatic cleavage of DAF from podocyte surfaces, leading to complement activation. C3 deficiency or prevention of C3a receptor (C3aR) signaling abrogates disease despite DAF deficiency, confirming complement dependence. Mechanistic studies show that C3a/C3aR ligations on podocytes initiate an autocrine IL-1β/IL-1R1 signaling loop that reduces nephrin expression, causing actin cytoskeleton rearrangement. Uncoupling IL-1β/IL-1R1 signaling prevents disease, providing a causal link. Glomeruli of patients with FSGS lack DAF and stain positive for C3d, and urinary C3a positively correlates with the degree of proteinuria. Together, our data indicate that the development and progression of glomerulosclerosis involve loss of podocyte DAF, triggering local, complement-dependent, IL-1β–induced podocyte injury, potentially identifying new therapeutic targets.

Immune deposits in skin vessels of patients with acute hemorrhagic edema of young children: A systematic literature review

BACKGROUND

Acute hemorrhagic edema of young children is a benign skin-limited vasculitis mainly affecting children 2 to 24 months of age, which is often considered the infantile variant of immunoglobulin A vasculitis (Henoch-Schönlein purpura). In most cases, the diagnosis is made on a clinical basis without a skin biopsy.

METHODS

A systematic review of the literature was performed to examine the reported prevalence of vascular immune deposits in skin biopsies of patients with acute hemorrhagic edema of young children.

RESULTS

Testing for vascular immune deposits was performed in 75 cases (64 boys and 11 girls aged from 3.5 to 72, median 11 months) published between 1970 and 2018. Vessel wall deposition of complement C3 was seen in 40 cases. Immunoglobulin M (N = 24), immunoglobulin A (N = 21), immunoglobulin G (N = 13), and immunoglobulin E (N = 3) were less frequently detected. Gender, age, clinical features, and disease duration were not statistically different in cases with and without vessel wall deposition of immunoglobulin A.

CONCLUSION

Immune deposits in skin vessels, most frequently complement C3, are common in subjects with acute hemorrhagic edema of young children, providing furhter evidence that acute hemorrhagic edema, immunoglobulin A vasculitis, and pauci-immune vasculitides are different entities.

Clinical significance of IgM deposition in pediatric minimal change disease

Background

Idiopathic nephrotic syndrome (INS) is a common pediatric disease. Minimal change disease (MCD) is the most common histopathological subtype and usually has good prognosis. However, in less common presentations, INS may have an unusual course that makes renal biopsy a necessity to identify its etiology. Immunoglobulin M (IgM) occasionally deposits in the mesangium and can be seen under immunofluorescence (IF). The role of IgM is controversial in MCD. It is likely associated with less favorable outcomes for MCD. This study aims to investigate the clinical significance of mesangial IgM deposits on the outcome of MCD in a pediatric population.

Methods

In this retrospective cohort study, we obtained native kidney biopsy samples from 192 children who were diagnosed with MCD from 2003 to 2014. The samples were divided into groups according to the histopathological deposition of IgM in biopsies under IF. The group for which biopsies showed IgM was labeled as IgM + IF (n = 77), and the group for which biopsies were without IgM was labeled as IgM-IF (n = 115). We reviewed hypertension, hematuria, and estimated glomerular filtration rate (eGFR) at the time of presentation to our institute; response to steroid therapy (remission, dependence, frequent relapses, and resistance) and response after adjuvant immunosuppressive therapy (complete remission, partial remission, frequent relapses, and no response) when indicated; development of chronic kidney disease (CKD) and end-stage renal disease during the course of the disease (ESRD).

Results

Our results showed that mesangial IgM deposition in MCD showed significant statistical association with hypertension at the time of presentation (P = .05). There was statistically significant association between the presence of IgM deposition and the development of steroid dependence (P = .05) and CKD during the course of the disease (P = .05).

Conclusions

Our study showed that IgM deposition in MCD showed statistical association with hypertension by the time the patient presented to our institute, development of steroid dependence, and CKD. IgM may play a role in MCD. However, we recommend a prospective study to verify the role of IgM in MCD outcomes.

Co-Deposition of IgM and C3 May Indicate Unfavorable Renal Outcomes in Adult Patients with Primary Focal Segmental Glomerulosclerosis

BACKGROUND/AIMS

We aimed to investigate the effects of glomerular IgM and C3 deposition on outcomes of adult patients with primary focal segmental glomerulosclerosis (FSGS).

METHODS

In this retrospective analysis, 86 consecutive adult patients with biopsy-proven primary FSGS were stratified into 3 groups according to their histopathological features: IgM- C3-, IgM+ C3-, and IgM+ C3+. Primary outcome was defined as at least a 50% reduction in baseline estimated glomerular filtration rate (eGFR) or development of kidney failure, while complete or partial remission rates were secondary outcomes.

RESULTS

Glomerular IgM deposits were found in 44 (51.1%) patients, 22 (25.5%) of which presented with accompanying C3 deposition. Patients in IgM+ C3+ group had higher level of proteinuria (5.6 g/24 h [3.77-8.5], p = 0.073), higher percentage of segmental glomerulosclerosis (20% [12.3-27.2], p = 0.001), and lower levels of eGFR (69 ± 37.2 mL/min/1.73 m2, p = 0.029) and serum albumin (2.71 ± 0.85 g/dL, p = 0.045) at the time of diagnosis. Despite 86.3% of patients in IgM+ C3+ group (19/22) received immunosuppressive treatment, the primary outcome was more common in patients in the IgM+ C3+ group compared with patients in IgM+ C3- and IgM- C3- groups (11 [50%] vs. 2 [9%] and 11 [26.1%] respectively [p = 0.010]). Complete or partial remission rates were lower in patients in the IgM+ C3+ group (5/22, 22.7%), as well (p = 0.043). Multivariate Cox regression analysis revealed that IgM and C3 co-deposition was an independent risk factor associated with primary outcome (hazard ratio 3.355, 95% CI 1.349-8.344, p = 0.009).

CONCLUSIONS

Glomerular IgM and C3 co-deposition is a predictor of unfavorable renal outcomes in adult patients with primary FSGS.

Glomerular C4d deposition can precede the development of focal segmental glomerulosclerosis

Recent studies suggest that complement plays a role in the pathogenesis of focal segmental glomerulosclerosis (FSGS). Moreover, co-localization of IgM and C3 deposits with FSGS lesions has frequently been reported. Here, we investigated whether glomerular complement deposition precedes the development of FSGS and whether it represents local complement activation. Renal biopsies from 40 patients with primary FSGS, 84 patients with minimal change disease, and 10 healthy individuals were stained for C4d, C1q, and mannose-binding lectin. C4d deposits were also measured in renal allograft biopsies from 34 patients with native primary FSGS, 18 of whom subsequently developed recurrent FSGS. Lastly, we measured C4d deposits in the Munich Wistar Frömter rat model of FSGS. The prevalence of C4d-positive glomeruli was significantly higher among patients with FSGS (73%) compared to patients with minimal change disease (21%) and healthy individuals (10%). Moreover, segmental sclerosis was absent in 42% of C4d-positive glomeruli. Glomerular C1q was significantly more prevalent in FSGS compared to minimal change disease or healthy individuals, while mannose-binding lectin was infrequently observed. C4d deposition was significantly more prevalent in recurrent FSGS (72%) before the development of sclerotic lesions compared to control transplant samples (27%). Finally, at the onset of albuminuria but before the development of FSGS lesions, Munich Wistar Frömter rats had a significantly higher percentage of C4d-positive glomeruli (31%) compared to control rats (4%). Thus, glomerular C4d deposition can precede the development of FSGS, suggesting that complement activation may play a pathogenic role in the development of FSGS.

Mutations in INF2 may be associated with renal histology other than focal segmental glomerulosclerosis

BACKGROUND

In 2010, INF2 mutations were associated with autosomal-dominant focal segmental glomerulosclerosis (FSGS), clinically presenting with moderate proteinuria in adolescence. However, in the meantime, cases with more severe clinical courses have been described, including progression to end-stage renal disease (ESRD) during childhood. INF2 mutations in patients with isolated FSGS are clustered in exons 2 to 4, encoding the diaphanous inhibitory domain, involved in the regulation of the podocyte actin cytoskeleton.

METHODS

We report a family with 14 affected individuals (autosomal-dominant mode of inheritance), most of whom presented with nephrotic-range proteinuria, hypertension, and progressive renal failure. Four members received a kidney transplant without disease recurrence. Two patients underwent renal biopsy with the result of minimal-change glomerulopathy and IgA nephropathy respectively. We performed mutational analysis of ACTN4, CD2AP, COQ6, INF2, LAMB2, NPHS1, NPHS2, PLCE1, TRPC6, and WT1 in the index patient by next-generation sequencing. Additionally, in 6 affected and 2 unaffected family members target diagnostics were performed.

RESULTS

We identified a novel heterozygous mutation c.490G>C (p.(Ala164Pro) in exon 3 of the INF2 gene in the index patient and 6 additionally examined affected family members. In silico analysis predicted it as "probably damaging". Additionally, three patients and 2 unaffected relatives harbored a novel heterozygous variant in ACTN4 (c.1149C>G, p.(Ile383Met)) with uncertain pathogenicity.

CONCLUSION

Mutations in INF2 are associated with familial proteinuric diseases - irrespective of the presence of FSGS and in the case of rapid disease progression. Therefore, mutational analysis should be considered in patients with renal histology other than FSGS and severe renal phenotype.

IgM as a novel predictor of disease progression in secondary focal segmental glomerulosclerosis

Aim

To determine the role of immunoglobulin M (IgM) deposits in clinical manifestations, disease outcome, and treatment response of idiopathic and secondary focal segmental glomerulosclerosis (FSGS).

Methods

Kidney biopsy specimens of 171 patients diagnosed with FSGS (primary and secondary) and 50 control patients were retrospectively included in the study. For each patient, clinical and outcome data were obtained and compared to morphological parameters, including immunofluorescence analysis of mesangial IgM and complement 3 (C3) deposits analyzed on kidney biopsy samples.

Results

There were significant positive correlations between IgM and C3 deposition in secondary FSGS (P < 0.001) and between IgM and mesangial deposits detected by electron microscopy in secondary FSGS (P = 0.015), which indicated that higher IgM deposition correlated with higher C3 deposition and mesangial deposits only in secondary FSGS. Patients with secondary FSGS and the deposition of IgM showed inferior renal outcomes at earlier time points in comparison with patients with negative IgM expression (P = 0.022).

Conclusions

We detected a positive correlation between IgM and C3 in secondary FSGS. The association between IgM deposition and worse renal outcome in secondary FSGS indicates that IgM may play a role in the progression of this disease.

The impact of IgM deposits on the outcome of Nephrotic syndrome in children

BACKGROUND

The significance of IgM deposits in glomerular mesangium has been controversial since they were first described due to the variations in the both the definitions used and described impact on clinical outcome. The aim of our study was to evaluate the significance of the IgM deposits in the glomerular mesangium for outcomes of nephrotic syndrome (NS) in children.

METHODS

Forty-five children with NS who underwent renal biopsy at tertiary pediatric hospital from January 1st, 2000 to December 31st, 2015 and the pathology diagnosis of minimal change disease, focal segmental glomerulosclerosis and mesangial hypercellularity (MH) were retrospectively analyzed. IgM positivity was defined as ≥1+ imunofluorescence with predominantly mesangial distribution. The patients were stratified into IgM-positive (n = 18) and IgM-negative (n = 27).

RESULTS

At the end of the median follow-up 4.5 years (range 0.17-13.14), the IgM-positive group was represented by 11 patients (61.1%) in remission, 3 patients (16.7%) with active disease and normal kidney function, 2 (11.1%) patients with active disease and impaired kidney function, 2 (11.1%) patients on renal replacement therapy. Accordingly, the IgM-negative group included 13 patients (48.1%) in remission, 12 (44.4%) with active disease and normal kidney function, 1 (3.7%) with active disease and impaired kidney function, 1 (3.7%) on renal replacement therapy, with no statistical significance between groups (p = 0.186).

CONCLUSIONS

This study did not reveal significant differences of the disease outcomes between IgM-positive and IgM-negative groups.

Idiopathic nephrotic syndrome: the EBV hypothesis

Steroid sensitive nephrotic syndrome is marked by a massive proteinuria and loss of podocytes foot processes. The mechanism of the disease remains debated but recent publications suggest a primary role of Epstein-Barr Virus (EBV). EBV replication in the peripheral blood is found in 50% of patients during the first flare of the disease. The genetic locus of steroid sensitive nephrotic syndrome was also identified as influencing antibodies directed against EBNA1. EBV is able to establish, latent benign infection in memory B cells that display phenotypes similar to antigen-selected memory B cells. Consistently, memory B cells reconstitution after rituximab infusion is a predictor of the relapse of proteinuria. We suggest that a specific anti-EBNA1 antibody internalized in the podocytes via the neonatal Fc receptor might cross-react with a major protein present in the same cell trafficking compartment. The diversion of this major podocyte protein in the urinary space and the subsequent depletion is supposed to result in podocyte damages with loss of foot processes and massive proteinuria. Immunosuppression of B cells and subsequent clearance of anti-EBNA1 antibodies would lead to a restoration of the normal level of the protein allowing recovery of proteinuria and of normal podocyte morphology.

Complement Activation in Patients with Focal Segmental Glomerulosclerosis

Background

Recent pre-clinical studies have shown that complement activation contributes to glomerular and tubular injury in experimental FSGS. Although complement proteins are detected in the glomeruli of some patients with FSGS, it is not known whether this is due to complement activation or whether the proteins are simply trapped in sclerotic glomeruli. We measured complement activation fragments in the plasma and urine of patients with primary FSGS to determine whether complement activation is part of the disease process.

Study Design

Plasma and urine samples from patients with biopsy-proven FSGS who participated in the FSGS Clinical Trial were analyzed.

Setting and Participants

We identified 19 patients for whom samples were available from weeks 0, 26, 52 and 78. The results for these FSGS patients were compared to results in samples from 10 healthy controls, 10 patients with chronic kidney disease (CKD), 20 patients with vasculitis, and 23 patients with lupus nephritis.

Outcomes

Longitudinal control of proteinuria and estimated glomerular filtration rate (eGFR).

Measurements

Levels of the complement fragments Ba, Bb, C4a, and sC5b-9 in plasma and urine.

Results

Plasma and urine Ba, C4a, sC5b-9 were significantly higher in FSGS patients at the time of diagnosis than in the control groups. Plasma Ba levels inversely correlated with the eGFR at the time of diagnosis and at the end of the study. Plasma and urine Ba levels at the end of the study positively correlated with the level of proteinuria, the primary outcome of the study.

Limitations

Limited number of patients with samples from all time-points.

Conclusions

The complement system is activated in patients with primary FSGS, and elevated levels of plasma Ba correlate with more severe disease. Measurement of complement fragments may identify a subset of patients in whom the complement system is activated. Further investigations are needed to confirm our findings and to determine the prognostic significance of complement activation in patients with FSGS.

IgM exacerbates glomerular disease progression in complement-induced glomerulopathy

While glomerular IgM deposition occurs in a variety of glomerular diseases the mechanism of deposition and its clinical significance remain controversial. Some have theorized IgM becomes passively trapped in areas of glomerulosclerosis. However, recent studies found that IgM specifically binds damaged glomeruli. Therefore, we tested whether natural IgM binds to neo-epitopes exposed after insults to the glomerulus and exacerbate disease in mice deficient in the complement regulatory protein factor H; a model of non-sclerotic and nonimmune-complex glomerular disease. Immunofluorescence microscopy demonstrated mesangial and capillary loop deposition of IgM while ultrastructural analysis found IgM deposition on endothelial cells and subendothelial areas. Factor H deficient mice lacking B cells were protected from renal damage, as evidenced by milder histologic lesions on light and electron microscopy. IgM, but not IgG, from wild-type mice bound to cultured murine mesangial cells. Furthermore, injection of purified IgM into mice lacking B cells bound within the glomeruli and induced proteinuria. A monoclonal natural IgM recognizing phospholipids also bound to glomeruli in vivo and induced albuminuria. Thus, our results indicate specific IgM antibodies bind to glomerular epitopes and that IgM contributes to the progression of glomerular damage in this mouse model of non-sclerotic glomerular disease.

Long-term outcome of children treated with rituximab for idiopathic nephrotic syndrome

BACKGROUND

Rituximab (RTX) has recently showed promising results in the treatment of steroid-dependent idiopathic nephrotic syndrome (SDNS).

METHODS

This was a retrospective multicenter study of 18 children treated with RTX for SDNS, with a mean follow-up of 3.2 years. RTX was introduced because of side effects or relapses during therapy with immunosuppressive agents. The children received one to four infusions of RTX during the first course of treatment, and subsequent infusions were given due to CD19-cell recovery (CD19 >1 %; 54 % of children) or relapse (41 %), as well as systematically (5 %).

RESULTS

Treatment with RTX maintained sustained remission without relapse in 22 % of patients and increased the duration of remission in all other patients. The time between two successive relapses was 9 months in the absence of re-treatment and 24.5 months when infusions were performed at the time of CD19-cell recovery. At the last follow-up, 44.5 % of patients were free of oral drug therapy. Of those still receiving oral drugs, all doses had been decreased. No serious adverse events occurred.

CONCLUSION

The results of this retrospective study confirm the efficacy and very good safety of RTX in the treatment of SDNS. The optimal therapeutic protocol seems to be a repeated single infusion at the time of CD19-cell recovery.

IgM contributes to glomerular injury in FSGS

Glomerular IgM and C3 deposits frequently accompany idiopathic FSGS and secondary glomerulosclerosis, but it is unknown whether IgM activates complement, possibly contributing to the pathogenesis of these diseases. We hypothesized that IgM natural antibody binds to neoepitopes exposed in the glomerulus after nonimmune insults, triggering activation of the complement system and further injury. We examined the effects of depleting B cells, using three different strategies, on adriamycin-induced glomerulosclerosis. First, we treated wild-type mice with an anti-murine CD20 antibody, which depletes B cells, before disease induction. Second, we evaluated adriamycin-induced glomerulosclerosis in Jh mice, a strain that lacks mature B cells. Third, we locally depleted peritoneal B cells via hypotonic shock before disease induction. All three strategies reduced deposition of IgM in the glomerulus after administration of adriamycin and attenuated the development of albuminuria. Furthermore, we found that glomerular IgM and C3 were detectable in a subset of patients with FSGS; C3 was present as an activation fragment and colocalized with glomerular IgM, suggesting that glomerular IgM may have bound a cognate ligand. Taken together, these results suggest that IgM activates the complement system within the glomerulus in an animal model of glomerulosclerosis. Strategies that reduce IgM natural antibody or that prevent complement activation may slow the progression of glomerulosclerosis.

IgM nephropathy revisited

IgM nephropathy (IgMN) is an idiopathic immune complex-mediated glomerulopathy that was first described as a distinct disease in a nephropathology literature in 1978. Here, a historical review and the current status of IgMN in the light of world literature and the current experience will be presented. The Pubmed (www.pubmed.gov) search was made for articles on IgMN as the sole subject of the study or where it constituted a significant number of cases in a biopsy series in the world literature written in English. A total of 41 articles were found. A critical review of the literature was made. Soon after 1978, a series of reports were published mostly from the western world, but the interest in the entity did not withstand the test of time. No substantial basic medical research was carried out and the disease was largely ignored by the western researchers. More recently, a flurry of articles have appeared in the literature on the topic, mostly from tropical countries, and have renewed the interest in the entity. However, most of the current literature on IgMN is based on clinical observations, and experimental models and mechanistic studies of IgMN are lacking. There is an urgent need to develop consensus based criteria for the diagnosis of the condition, as well as, to focus the research on mechanistic studies to understand the pathogenesis of the disease better.

Clinicopathologic characteristics and steroid response of IgM nephropathy in children presenting with idiopathic nephrotic syndrome

There is no detailed information on clinical and immunopathologic features of immunoglobulin M nephropathy (IgMN) in children with idiopathic nephrotic syndrome (INS) in Pakistan. We reviewed our native renal biopsies over 15 years (July 1995-July 2010) and identified 135 cases of IgMN in nephrotic children (≤17 years). Their demographic, clinical and immunopathologic data were retrieved from biopsy reports and case notes. Mean age of this cohort was 7.6 ± 4.2 years. Males were 92 (68.1%) and females were 43 (31.9%). Steroid-dependent NS was seen in 88 (65.2%) cases and steroid-resistant NS in 47 (34.2%). Hematuria was found in 42 cases (31.2%) and hypertension in 27 (19.5%). The most common morphologic change was glomerular mesangial proliferation, found in 89 (65.9%) biopsies. Minor changes were seen in 46 (34.1%) cases and focal segmental glomerulosclerosis (FSGS) in 37 (27.4%). Immunofluorescence microscopy showed diffuse mesangial positivity of IgM in all cases. C3 and C1q were found in 72 (53.3%) and 40 (29.7%) cases, respectively. Our results show that IgMN is a fairly common cause of INS in children in Pakistan. It shows a spectrum of morphologic changes ranging from minor changes to FSGS.

Childhood nephrotic syndrome in Cambodia: an association with gastrointestinal parasites

OBJECTIVES

To describe childhood nephrotic syndrome (NS) in Cambodia and to evaluate whether initial presentation or relapse is associated with gastrointestinal parasitic infection.

STUDY DESIGN

We reviewed the records of 112 children with NS. A retrospective cross-sectional study compared 99 stool exams from 63 children with NS with 12 365 stool exams from 9495 controls.

RESULTS

The male-to-female ratio was 1.7; the mean age of presentation was 8.95 years--44% were hypertensive, 44% had microscopic hematuria, 40% had eosinophilia, and 41% had acute renal failure; 92.7% were steroid sensitive, 12.7% were steroid dependent, and 8.9% were frequent relapsers. Peritonitis and death were rare outcomes. Giardia lamblia (OR, 3.62; 95% CI, 2.0 to 6.1), Strongyloides stercoralis (OR, 3.59; 95% CI, 1.3 to 8.2), and Hookworm species (OR, 2.57; 95% CI, 1.0 to 5.5) were more likely to be isolated from the children with NS than the controls.

CONCLUSIONS

The clinical course of childhood NS in Cambodia is similar to the developed world. Differences at presentation included older age and increased prevalence of microscopic hematuria, hypertension, eosinophilia, and acute renal failure. This study demonstrates an association between G lamblia, S stercoralis, and possibly Hookworm species and the onset of NS.

Stem cell mobilization in idiopathic steroid-sensitive nephrotic syndrome

Steroid-sensitive nephrotic syndrome (SSNS) is classically thought to be a T-cell disorder. The aim of this study was to examine whether or not thymus homeostasis was affected in SSNS. Mature and naive T cell recent thymic emigrants were quantified in the peripheral blood of nephrotic patients and controls. Because the generation of new T cells by the thymus ultimately depends on hematopoietic stem cells, CD34+ cells were also included in the study. Nineteen patients with SSNS during relapse, 13 with SSNS during proteinuria remission, and 18 controls were studied. Cell-surface markers (CD3, CD4, CD8, CD19, CD16, CD56, CD45RA, CD62L, CD34, and CD38) were analyzed by flow cytometric analysis. T-cell rearrangement excision circles (TRECs) were quantified in CD2+ cells by real-time polymerase chain reaction. Stroma cell-derived factor-1 (SDF-1) genotype and metalloproteinase-9 (MMP-9) plasma levels were also determined. Mature T cells (CD4+ and CD8+), circulating naive T cells (CD62L+ and CD3+ CD62L+), and recent thymic emigrants (CD45RA+) as well as TRECs, that measure thymus production, had a similar level in the three groups of patients. Conversely, CD34+ hematopoietic stem cells displayed a two-fold increase in SSNS patients during relapse either compared with controls or SSNS patients at remission. In addition, compared with controls, SSNS patients at remission displayed (1) a decrease in CD19+ cells (B cells) and (2) an increase in CD16CD56+ cells [natural killer (NK) cells]. In conclusion, thymus homeostasis is not significantly affected in nephrotic patients. Hematopoietic stem-cell mobilization at proteinuria relapse, as well as changes in B and NK cells during remission, suggest that SSNS might be due to a general disturbance of hematopoietic and immune cell trafficking.

Rituximab treatment for severe steroid- or cyclosporine-dependent nephrotic syndrome: a multicentric series of 22 cases

Several case reports suggest that rituximab (RTX) could be effective in steroid-dependent nephrotic syndrome, but RTX efficacy has not yet been studied in a series of patients. Safety and efficacy of RTX were assessed in a multicenter series of 22 patients aged 6.3-22 years with severe steroid-dependent nephrotic syndrome or steroid-resistant but cyclosporin-sensitive idiopathic nephrotic syndrome. Patients were treated with two to four infusions of RTX. Seven patients were nephrotic at the time of RTX treatment. Peripheral B cells were depleted in all subjects. Remission was induced in three of the seven proteinuric patients. One or more immunosuppressive (IS) treatments could be withdrawn in 19 patients (85%), with no relapse of proteinuria and without increasing other IS drugs. RTX was effective in all patients when administered during a proteinuria-free period in association with other IS agents. When relapses occurred, they were always associated with an increase in CD19 cell count. Adverse effects were observed in 45% of cases, but most of them were mild and transient. This study suggests that RTX could be an effective treatment for severe steroid-dependent nephrotic syndrome.

Mesangial hypercellularity in children: presenting features and outcomes

Mesangial hypercellularity (MH), in the absence of sclerosis or immune deposition, was a common finding on renal biopsy in our center. We studied 66 children with predominant MH. Among all patients older than 2.7 years, blood pressure (BP) percentile and glomerular filtration rate (GFR) remained stable. Serum albumin (Alb) trended higher (3.0+/-0.2 start vs. 3.4+/-0.2 end g/dl, p=0.06) and urine protein/creatinine lower (4.2+/-0.9 start vs. 2.3+/-0.9 end mg/mg, p=0.18) at the end of the study period. The proportion with stage 1 CKD remained constant: 94% start vs. 92% end. At end, Alb was lower in patients referred for nephrotic syndrome (NS): 4.4+/-0.3 hematuria vs. 4.2+/-0.2 proteinuria vs. 2.8+/-0.3 NS g/dl, p<0.05 vs. both. Alb was lower (p=0.03) and urine protein/creatinine trended higher in patients with diffuse foot-process fusion (FPF). Twenty-five percent of patients with focal FPF developed NS, all had relapses, and 63% were steroid sensitive (SS). All but one with diffuse FPF presented with NS; 86% had relapses (mean 1 year) and 63% were SS. GFR trended higher at the end in those with matrix thickening (mat) (119.6+/-4.7 no mat vs. 129.1+/-2.6 mat ml/min per 1.73 m2, p=0.1). Those without mat were less SS (59% no mat vs. 80% mat) and were more likely to require alkylating agents (Alk) for NS. Among those with positive immunofluorescence (IF), 82% had immunoglobulin M (IgM) alone; those with positive IF were more SS and needed Alk for NS. MH predicts a favorable prognosis. FPF predicts NS and multiple relapses.

Steroid-responsive nephrotic syndrome in a child with juvenile idiopathic arthritis

Renal disease is rare in children with juvenile idiopathic arthritis, although a number of associated nephropathies have been described, including mesangial glomerulonephritis. We report the presence of mesangial glomerulonephritis, revealed by a nephrotic syndrome, in a paediatric patient with juvenile idiopathic arthritis. Short-term steroid treatment induced a rapid remission of the nephrotic syndrome, but the presence of anti-nuclear antibodies, 1:320 in a homogeneous pattern, irregular deposits of C1q in a renal biopsy, and a mother with episodes of cutaneous lupus suggested an uncertain renal evolution for this infant.

Immunohistochemical detection of galectin-1 in renal biopsy specimens of children and its possible role in proteinuric glomerulopathies

AIMS

Galectin-1 is an endogenous lectin that specifically binds to beta-galactoside structures. It has been associated with developmental mechanisms ranging from differentiation to apoptosis and exerts immunoregulatory functions in autoimmune diseases. The aim was to determine the immunohistochemical expression of galectin-1 in renal biopsy specimens of children with primary idiopathic proteinuric glomerulopathies.

METHODS AND RESULTS

We examined 18 children with minimal change disease (MCD), 30 with diffuse mesangial proliferation (DMP) and 11 with focal segmental glomerulosclerosis (FSGS). An indirect immunohistochemical protocol using a polyclonal antibody directed against galectin-1 was applied. Galectin-1 was detected in renal podocytes in DMP and FSGS cases, while control glomeruli and MCD were negative. Galectin-1 immunoreactivity was found within parietal epithelial cells in patients with FSGS.

CONCLUSIONS

These results suggest a possible role for galectin-1 in the pathogenesis of primary glomerulopathies in children as a kind of podocyte-related self-protective activity and probably involvement of epithelial cells of Bowman's capsule in inflammatory processes. Immunohistochemistry using galectin-1 antibodies may further be helpful in histological distinction between MCD and DMP.

Unusual presentation of IgA nephropathy in childhood: a case report

Immunoglobulin A (IgA) nephropathy is the most common form of primary glomerulonephritis worldwide, and approximately 20% to 30% of adult patients with the disorder develop chronic renal failure within 20 years. This type of nephropathy is also an important risk factor for chronic renal failure in children. The pathogenesis of IgA nephropathy is still unknown, and treatment remains controversial. Microscopic hematuria and recurrent episodes of macroscopic hematuria are the most common clinical manifestations of this condition in children. This article describes the case of a young girl who presented with steroid-resistant nephrotic syndrome unaccompanied by hematuria. Renal biopsy findings were consistent with IgA nephropathy. The patient's condition was a rare clinical manifestation of IgA nephropathy.

Long-term outcome of heavy proteinuria in patients under 2 years of age

From January 1985 to July 2000, a retrospective study of 53 patients in Taiwan was performed in order to evaluate the underlying diseases causing heavy proteinuria and the clinical outcome in children under 2 years of age (33 boys and 20 girls). Renal biopsy or autopsy was performed in 26 of the children. Renal pathology revealed 2 patients with congenital nephrosis (CNS) (7.7%), 4 with diffuse mesangial sclerosis (DMS) (15.4%), 4 with minimal change nephrotic syndrome (MCNS) (15.4%), 5 with focal segmental glomerulosclerosis (FSGS) (19.2%), 9 with IgM nephropathy in (34.6%), and 2 with hepatitis B virus-associated membranous glomerulonephritis (7.7%). Based on available histology and family history of heavy proteinuria progressing to end-stage renal disease (ESRD), patients were divided into two groups. Group I comprised 10 patients, including CNS (2 cases), DMS (4 cases), and 4 children with a familial history of heavy proteinuria progressing to ESRD. All patients in group I were initially steroid resistant. After methylprednisolone pulse therapy plus cyclosporin A treatment, no patients with CNS or DMS responded, but the other 4 patients experienced a remission. Group II comprised 43 patients; 19 patients (44.2%) were initially steroid resistant. Of these steroid-resistant patients, all experienced remission after methylprednisolone pulse therapy plus cyclosporin A, except 3 children with FSGS. One experienced a thromboembolic event during his clinical course. In conclusion, steroid-resistant nephrotic syndrome (NS) was more common than steroid-sensitive NS in Chinese patients under 2 years of age. Patients with CNS, DMS, or a family history of heavy proteinuria progressing to ESRD had a poor prognosis. Methylprednisolone pulse therapy plus cyclosporin A treatment achieved remission in some children who were initially steroid resistant. This study indicates that children with conditions associated with poor steroid responsiveness (e.g., CNS, DMS) do not respond to immunosuppressive therapy, but other children under 2 years of age, including those with a family history of progression to ESRD, may benefit from aggressive immunosuppressive therapy.

Glomerulopathy with mesangial IgM deposits: long-term follow up of 64 children

BACKGROUND

The aim of the present study was to investigate to what extent IgM nephropathy in children with minimal change nephrotic syndrome (MCNS) and diffuse mesangial hypercellularity (DMH) evolves to focal segmental glomerulosclerosis (FSGS).

METHODS

Tissues from renal biopsies were examined by light microscopy (LM), immunofluorescence (IF) and, in four cases, by electron microscopy (EM). From a total of 352 nephrotic children, 121 had renal biopsy results as steroid dependent or resistant. A diagnostic renal biopsy was also performed in 331 children with non-nephrotic proteinuria and/or hematuria. A second renal biopsy was performed in 16 children whose renal function was impaired during the follow up. The clinical course of IgM-positive children was compared with that of IgM-negative children.

RESULTS

Of the 121 nephrotic children with renal biopsy, 85 were MCNS. Twenty were IF positive mainly for IgM, six of whom (30%) presented evolution to FSGS, while of the remaining 65 IF-negative children, only three (4.6%) presented evolution to FSGS. Of the total 331 children with non-nephrotic proteinuria and/or hematuria, 139 were diagnosed as IgA--IgG nephropathy, 44 had positive IF for IgM and 148 were IF negative. Of the 44 children IF positive for IgM, seven (15.9%) presented evolution to FSGS, while none of the 148 IF-negative children presented evolution to FSGS. The follow-up time for all children ranged from 1 to 14 years.

CONCLUSIONS

Of IgM nephropathy patients with MCNS and DMH, a significant percentage develop impaired renal function, due to the evolution of FSGS, as revealed by repeat biopsy during long-term follow up.

[Molecular mechanisms of idiopathic nephrotic syndrome]

Steroid-sensitive idiopathic nephrotic syndrome is a T-cell disorder associated with a functional renal impairment. The molecular mechanisms leading from the stimulation of the immune system to the clinical expression of the renal disease can be analyzed according to five biological events: 1) a Th2 activation of T-cells by interleukin-13; 2) a yet unidentified glomerular permeability factor from immune origin; 3) a molecular disorientation of slit diaphragms or glomerular basement membrane responsible for proteinuria; 4) a podocyte cytoskeleton rearrangement responsible for foot process effacement; and 5) renal avidity for sodium and edema formation resulting from a primary stimulation of tubular Na,K-ATPase and an increase of endothelial permeability.

Adult-onset idiopathic nephrotic syndrome associated with pure diffuse mesangial hypercellularity

BACKGROUND

Pure diffuse mesangial hypercellularity (DMH), in its primary form, is a relatively rare histological finding and few data exist in the literature regarding its clinical course and prognosis in nephrotic adults with this diagnosis.

METHODS

We retrospectively analysed the clinical and histological data of 28 adult nephrotic patients (13 male) with this diagnosis with regard to response to the treatment, outcome and prognostic indicators.

RESULTS

Of 25 patients treated with prednisolone (Pred), nine (36%) showed complete remission (CR) of proteinuria, eight (32%) partial remission (PR) and eight (32%) did not respond at all (NR). The combination of cyclosporin treatment with prednisolone of those with PR or NR produced one further complete and two partial remissions. At the end of follow-up (mean 64 months), 10 patients (40%) were in CR, nine (36%) in PR and six (24%) were NR and remained nephrotic. Renal function remained unchanged in patients with CR or PR. In contrast, the six non-responders progressed to end-stage renal disease (ESRD). Compared with non-responders, patients who responded to Pred were older and had normal renal function at presentation. This group also had less mesangial sclerosis and severe tubulointerstitial fibrosis and none showed synechiae with Bowman's capsule. IgM mesangial deposits were observed in 22% of patients with CR in response to Pred, in 37% of those with PR and in 100% of non-responders, who finally progressed to ESRD. A multivariate analysis of clinical and histological features at biopsy showed persistent nephrotic syndrome (P<0.001), the severity of DMH (P<0.03) and the presence of mesangial IgM (P<0. 01) to have independent predictive value for ESRD. This analysis also demonstrated that only mesangial sclerosis (P<0.03) and the presence of mesangial IgM (P<0.002) independently predicted the response to therapy.

CONCLUSIONS

DMH associated with idiopathic nephrotic syndrome is a heterogeneous entity. Patients who respond to therapy (completely or partially) have a benign course similar to that of minimal change nephrotic syndrome. They are usually older and have normal renal function at presentation, whereas 'sclerotic' lesions are less frequent findings in initial biopsies. Non-responders tend to be younger and progress to ESRD. Most of them have impaired renal function at first assessment and more prominent 'sclerotic' lesions on initial biopsies. Mesangial IgM is an independent marker of poorer response to treatment and progression to ESRD but it lacks specificity.

Morphological studies of baseline needle biopsies from living donor kidneys: light microscopic, immunohistochemical and ultrastructural findings

Fifty-seven consecutive living donors (31 women and 26 men aged 20.7-72.3 years, mean 50.6 years) were subjected to needle biopsy during nephrectomy, immediately before removal of the kidney. By light microscopy, semiquantitative scoring (0-3) was performed for arteriosclerosis, arteriolar hyalinosis (hyalin arteriolosclerosis), glomerulosclerosis, interstitial mononuclear cell infiltration, and interstitial fibrosis/tubular atrophy. Whereas vascular changes were striking in many biopsies (arteriosclerosis grades 2-3: 28/54 cases, arteriolar hyalinosis grades 2-3: 15/55 cases), glomerular and tubulointerstitial changes were mostly low grade. The morphological changes tended to be more pronounced in middle-aged and older individuals, but, in particular, vascular changes were seen also in the younger age group. Immunofluorescence microscopy revealed glomerular granular staining for IgM in 52.7% of the cases, IgA in 9.1%), IgG in 1.8%, and C3 in 12.7%. The main ultrastructural finding was glomerulosclerosis; one case with diffuse glomerular IgA showed distinct dense deposits, and one case showed similar dense deposits without IgA deposition. Arteriolar wall deposition of C3 was found in 58.2% of the cases, and IgM in 10.9%. Especially C3 occurred both with arteriolar hyalinosis and in arterioles without light microscopic alterations. The observation of significant vascular changes in baseline biopsies is relevant especially in the differential diagnosis of chronic rejection and cyclosporine nephropathy. The immunohistochemical findings strongly indicate the occurrence of immunoglobulins and complement factor C3 in both glomeruli and arterioles without clinical or morphological signs of renal disease. The possible pathophysiological significance of such deposits remains, however, uncertain.

Outcome of idiopathic childhood nephrotic syndrome. A 20 year experience

112 patients with idiopathic childhood nephrotic syndrome have been referred from 1970 through 1989 at the Department of Pediatrics, University of Berne. One patient remitted spontaneously without medication. Ninety-eight patients responded to prednisone: 15 had a single bout of nephrosis, 47 developed a tendency towards relapses and 36 steroid dependence. In 28 patients with tendency towards relapses cure took place on either prednisone alone or prednisone plus cyclophosphamide. In 18 patients with steroid dependency cure took place on prednisone alone or prednisone plus cyclophosphamide. Thirteen patients failed to respond to steroids. The course of the disease was more benign in 68 patients with minimal change disease as compared with 14 patients with focal and segmental glomerular sclerosis. Immunofluorescence studies demonstrated mesangial IgM deposits in 14 out of 54 patients, but this finding was not a marker for poor steroid response or progression to renal failure. The course of the disease was especially unfavourable in patients with persisting nephrosis on completion of the initial course of steroid therapy. In conclusion it appears appropriate to define the disease in terms of steroid responsiveness as steroid resistant patients sometimes show normal glomeruli, steroid responsive sometimes have focal and segmental glomerular sclerosis or mesangial IgM deposits, and decisions depend more on the steroid responsiveness than on the histological features.

A case of congenital nephrotic syndrome associated with positive C1q immunofluorescence

We present a 1-month-old girl with a congenital nephrotic syndrome and unusual histological findings. Immunofluorescence microscopy demonstrated granular mesangial deposition of C1q and electron microscopy revealed electron-dense mesangial deposits. Her heavy proteinuria gradually decreased and the steroid therapy did not have a significant effect. Her renal function was normal throughout the entire period of observation. The clinical evidence and histopathological features of this patient were compatible with C1q nephropathy.

A randomized trial of cyclosporine in steroid-resistant idiopathic nephrotic syndrome

To compare the efficacy (induction of remission) and safety of cyclosporine (CsA) with those of supportive therapy in patients with steroid-resistant idiopathic nephrotic syndrome (INS), we organized an open, prospective, randomized, multicentric, controlled study for parallel groups, stratified for adults and children. Forty-five patients with steroid-resistant INS were randomly assigned to supportive therapy or CsA (5 mg/kg/day for adults, 6 mg/kg/day for children) for six months, then tapered off by 25% every two months until complete discontinuation. Four patients were lost to follow-up. During the first year 13/22 CsA-treated patients versus three of 19 controls attained remission of the nephrotic syndrome (P < 0.001). A symptom score was assessed at time 0 and at six months. The mean score significantly decreased in the CsA group (P < 0.001), but remained unchanged in the controls. At month 6 the mean urinary protein excretion, the mean serum proteins and plasma cholesterol had significantly improved in the CsA group but were not changed in the controls. There were no significant differences in serum creatinine and creatinine clearance between treatments (interaction time* treatments, P = 0.089 and P = 0.935, respectively) at month 6 versus basal. The CsA-related side-effects were mild; no significant difference in blood pressure between the two groups was seen at any time. This study shows that CsA can bring about remission in some 60% of patients with steroid-resistant INS. In patients with normal renal function and without severe hypertension, CsA at the therapeutic scheme adopted did not produce severe renal or extrarenal toxicity.