Childhood nephrotic syndrome

Single (375 mg/m2) vs. double dose of rituximab along with mycophenolate mofetil for children with steroid-dependent/frequently relapsing nephrotic syndrome: a multicentre open-label randomized controlled trial

BACKGROUND

Optimal dosing of rituximab when given with mycophenolate mofetil (MMF) for frequently relapsing nephrotic syndrome/steroid-dependent nephrotic syndrome (FRNS/SDNS) remains uncertain.

METHODS

This was a prospective, non-inferiority, open-label randomized controlled multicentre study. Children (2-18 years old) with difficult FRNS/SDNS were randomized to group A (rituximab 375 mg/m2 once) or group B (rituximab 375 mg/m2 twice; 7-14 days apart) followed by continuous MMF and 3 months of tapered steroids. Primary outcome at an 18-month follow-up was time to first relapse. Secondary outcomes included post rituximab time to CD19 repopulation, sustained remission and significant adverse events (SAEs).

RESULTS

Ninety-six children (median age 8.6 years; IQR 6.4 to 11.3 years, 72% male) were randomized, 48 per arm. CD19 depletion (< 1%) was achieved in both groups. Three from single dose and two from double dose arm were lost to follow-up or withdrew. After 18 months, although non-inferiority could not be demonstrated, there was no difference in primary outcome either by intention-to-treat or per-protocol analysis. The restricted mean time to first relapse was 14.5 months (95% CI 13.1-15.9) in group A and 14.8 months (95% CI 13.5-16.1) in group B (p = 0.69). Relapse rate was similar between group A (19/45; 42%) and group B (16/46; 35%) (p = 0.53, hazard ratio 0.86 (95% CI 0.46-1.6)). Secondary outcomes were also similar between the groups.

CONCLUSIONS

Among children with FRNS/SDNS although non-inferiority could not be demonstrated, no statistically significant difference in outcome was found between 375 and 750 mg/m2 rituximab when accompanied with MMF.

Poria cocos: traditional uses, triterpenoid components and their renoprotective pharmacology

Poria cocos and its surface layer of Poria cocos (Schw.) Wolf (Polyporaceae), are used in traditional Chinese medicine for its diuretic and renoprotective effects. Phytochemical studies have shown that lanostane and 3,4-seco-lanostane tetracyclic triterpenoids are the main components of P. cocos and its surface layer. Accumulating evidence shows that triterpenoid components in P. cocos and its surface layer contribute to their renoprotective effect. The surface layer of P. cocos showed a stronger diuretic effect than P. cocos. The ethanol extract of the surface layer and its components improved acute kidney injury, acute kidney injury-to-chronic kidney disease transition and chronic kidney disease such as diabetic kidney disease, nephrotic syndrome and tubulointerstitial nephropathy, and protected against renal fibrosis. It has been elucidated that P. cocos and its surface layer exert a diuretic effect and improve kidney diseases through a variety of molecular mechanisms such as aberrant pathways TGF-β1/Smad, Wnt/β-catenin, IκB/NF-κB and Keap1/Nrf2 signaling as well as the activation of renin-angiotensin system, matrix metalloproteinases, aryl hydrocarbon receptor and endogenous metabolites. These studies further confirm the renoprotective effect of P. cocos and its surface layer and provide a beneficial basis to its clinical use in traditional medicine.

Comparison of B lymphocyte profile between membranous nephropathy and idiopathic nephrotic syndrome pediatric patients

BACKGROUND

Membranous nephropathy (MN) and idiopathic nephrotic syndrome (INS) are two B-cell mediated rare glomerular diseases that benefit from treatment with B-cell depleting anti-CD20 monoclonal antibody rituximab. Different B-cell dysregulations have been described in pediatric INS patients and in adults affected by MN. In adult MN patients, an increased level of mature-naïve cells and atypical memory B cells and a significant reduction in IgM memory and switched memory B cells have been previously described compared to healthy individuals. To date, there is no information available about B-cell immunophenotyping in pediatric MN.

METHODS

In this monocentric retrospective case-control study, we analyzed by flow cytometry the B-cell profile in rituximab-naïve (n = 15) children affected by MN, compared with pediatric INS patients (n = 15) selected by propensity score matching, and both evaluated during active disease. Age-matched controls (n = 15) with non-immune-mediated kidney diseases were also characterized. Demographical, clinical, laboratory, and immunosuppressive treatment data were registered.

RESULTS

We found that children with MN and INS had significantly higher circulating levels of total CD19+, mature-naïve, and atypical memory B cells and similar levels of transitional B cells when compared to age-matched controls. Circulating levels of total memory B cells, IgM memory B cells, and plasmablasts/plasmacells were significantly higher in INS patients compared to both MN patients and age-matched controls.

CONCLUSIONS

Our study indicated that children affected by MN had a specific B-cell profile and that high levels of memory B-cell subsets are specific to INS pediatric patients independently of proteinuria intensity.

Time to remission in childhood steroid sensitive nephrotic syndrome: a change in perspective

Time to remission (TTR) has been largely considered one of the predictive factors for the risk of relapse and steroid dependency in childhood steroid-sensitive nephrotic syndrome, yet conflicting opinions exist. However, the factors influencing TTR have never been studied. We performed a post-hoc analysis of the prospective pediatric cohort enrolled in a previous multicenter study (ClinicalTrials.gov Id: NCT01386957) to evaluate the possible influence of some clinical and laboratory parameters at INS onset on the timing of TTR. A total of 136 children were evaluated. In simple linear regression models, TTR was directly correlated with serum uric acid, urea, potassium, and urinary protein levels at onset. TTR showed a non-linear inverse correlation with age at onset. A multiple linear regression model of TTR showed that hyperuricemia (p = 0.0000007), non linear age (p = 0.0006) and proteinuria (especially in binary form) (p = 0.02) were significant predictors of TTR, and that there was a significant positive interaction between uricemia and proteinuria as predictors of TTR (p = 0.004). Conclusions: In our analysis, TTR appears to be associated to a nephrotic status at clinical diagnosis characterized by more severe proteinuria and hyperuricemia. Moreover, younger age at onset, notably associated with prognosis, is also associated with a longer TTR. What is Known: • Corticosteroids are the first-line treatment in childhood nephrotic syndrome. • Over the years, time to remission has been considered a potential predictive factor for the risk of relapse and steroid dependency in childhood nephrotic syndrome, with conflicting results. What is New: • Clinical and laboratory parameters at nephrotic syndrome onset are associated with prolonged time to remission in children.

Amino acid variants in the HLA-DQA1 and HLA-DQB1 molecules explain the major association of variants with relapse status in pediatric patients with steroid-sensitive nephrotic syndrome

BACKGROUND

Management of patients with steroid-sensitive nephrotic syndrome (SSNS) is challenging because of frequent relapses. Causal variants in the human leukocyte antigen (HLA) class II region that are associated with relapse remain undetermined.

METHODS

We collected a cohort of East Asian individuals comprising 206 pediatric patients with SSNS and 435 healthy controls from Southwest China. Ninety children with steroid-sensitive nephrotic syndrome without relapse (SSNSWR) and 116 children with steroid-dependent and/or frequent relapse nephrotic syndrome (SDNS/FRNS) were genotyped using Sanger sequencing. We then measured the transcriptional level, allele expression imbalance (AEI) and functional proteins of HLA-DQA1 and HLA-DQB1 in different stages of SDNS/FRNS.

RESULTS

rs1464545187 in ANKRD36 was associated with an approximately 1.69-fold greater risk for SSNSWR (P = 0.04; 95% confidence interval [CI], 1.05-2.72). Clustered risk variants in HLA-DQA1 and HLA-DQB1 were significantly associated with SDNS/FRNS (rs1047989: P = 2.26E-07, odds ratio [OR] = 2.25, 1.65-3.05; rs9273471: P = 5.45E-05, OR = 1.84, 1.37-2.46; HLA-DQB1*06:02: P = 0.017, OR = 0.19, 0.04-0.77). The genotype distributions of rs1047989, 2:171713702, rs1049123, rs9273471, and HLA-DQB1*06:02 in patients with SSNS were significantly different from those in healthy controls. rs1047989 (HLA-DQA1) was significantly associated with a greater number of infections at relapse in SDNS/FRNS patients (P = 0.045, OR = 6.79, 95% CI: 1.29-168.52). Flow cytometry showed that the proportion of cells expressing HLA-DQA1+/DQB1+ (HLA-DQA1+, P = 0.0046; HLA-DQB1+, P = 0.0045) was lowest in the relapse stage. In addition, the mRNA levels of HLA-DQA1 and HLA-DQB1 were significantly greater in the relapse group than in the remission group (HLA-DQA1, P = 0.03; HLA-DQB1, P = 0.002). No significant AEIs were detected in the different stages of SDNS/FRNS. The rs1047989 variant is likely to affect the structure and stability of HLA-DQA1.

CONCLUSION

rs1464545187 is a risk locus for SSNSWR but not SDNS/FRNS in Chinese children. Functional variations in HLA-DQA1 and HLA-DQB1 are implicated in regulating the immune response of SSNS patients, which may explain the typical triggering of SDNS/FRNS onset by infections.

A "Trial within a Cohort" platform for pediatric clinical trials on idiopathic nephrotic syndrome: scope, objectives, and design of the retrospective-prospective cohort PIN'SNP

BACKGROUND

Idiopathic nephrotic syndrome (INS) in children is the most common glomerular disease and is characterized by recurrent relapses. There is no community consensus on the treatment of relapsing forms of nephrotic syndrome in children, unlike that for the initial presentation. To date, available treatments only enable relapsing patients to be maintained in remission, rather than modifying the course of the disease; therefore, more therapeutic trials are needed. The Société de Néphrologie Pédiatrique (SNP) decided to implement within its French centers a national coordinated long-term clinical research program for children treated for INS based on a Trials within Cohorts (TwiCs) model. The aim of this paper is to describe the PIN'SNP cohort and research program as well as the TwiCs design adapted to INS research in the French regulatory system.

METHODS

This retrospective-prospective, multicenter research program will rely on a dynamic prospective cohort of children followed for an INS, known as the PIN'SNP cohort (i) to identify cases treated within SNP centers, (ii) to describe their clinical and epidemiological characteristics, and (iii) to provide a platform to nest prospective trials, and thus facilitate inclusion of patients in these future trials.

CONCLUSIONS

The PIN'SNP cohort is the first French national pediatric platform dedicated to the implementation of randomized nested trials along with longitudinal and observational studies on INS in children. The adaptation of the TwiCs design to inform all eligible patients/parents to each nested trial will facilitate methodological robustness and ethical acceptability and reinforce communication between investigators and participants.

TRIAL REGISTRATION

number NCT04207580.

Autoantibodies Targeting Proteasome Subunit Alpha Type 1 in Autoimmune Podocytopathies

Key Points

Serum anti-proteasome subunit alpha type 1 (PSMA1) autoantibodies were specifically elevated in the active phase of idiopathic nephrotic syndrome, which may assist in disease diagnosis and monitoring. Serum anti-PSMA1 antibodies could cause damage to the glomerular filtration barrier, which may be a pathogenic antibody of idiopathic nephrotic syndrome. PSMA1 played an important role in the maintenance of podocyte morphology and function.

Background

The antibody against proteasome subunit alpha type 1 (PSMA1) is a podocyte autoantibody in children with idiopathic nephrotic syndrome identified in our previous study. The aim of this study was to explore the characteristics of idiopathic nephrotic syndrome in children and the mechanism underlying its involvement in the development of idiopathic nephrotic syndrome.

Methods

The levels of serum anti-PSMA1 autoantibodies in children were detected through protein microarray and compared among different disease groups. The recombinant PSMA1 protein was injected subcutaneously and intraperitoneally into mice to observe glomerular morphology and function. The PSMA1-knockdown and PSMA1-overexpressing cell lines were constructed from mouse podocytes, and their cytoskeleton and function were analyzed. Homozygous zebrafish with psma1 knockout were observed.

Results

The levels of serum anti-PSMA1 autoantibodies were higher in children with idiopathic nephrotic syndrome and varied with urinary protein. In mice immunized with PSMA1, the presence of serum anti-PSMA1 autoantibody caused albuminuria and damage to the glomerular filtration membrane. Deficiency of PSMA1 impaired the podocyte cytoskeleton and physiological function. Complete deletion of psma1 caused edema, abnormal glomerular morphology, and effacement of foot processes in zebrafish.

Conclusions

PSMA1 played an important role in the maintenance of podocyte morphology and function.

Causal relationships between immune cell phenotypes and primary glomerular diseases: genetic evidence from bidirectional Mendelian randomization study

Background

Primary glomerular diseases (PGDs), including nephrotic syndrome (NS), membranous nephropathy (MN), and IgA nephropathy (IgAN), are complex renal conditions influenced by immune system dysregulation. Although associations between immune cell phenotypes and PGDs have been observed, the precise causal relationships have not been fully elucidated.

Methods

Utilizing genetic association data from genome-wide association studies (GWASs), we investigated 731 immunophenotypes in relation to PGDs. A bidirectional two-sample Mendelian randomization (MR) approach, primarily employing inverse variance weighting (IVW), was conducted to establish causality. MR-Egger, weighted median, simple mode, and weighted mode were used as complementary methods to reinforce the robustness and validity of the results. Sensitivity analyses further validated the sensitivity and stability of our results.

Results

We identified 38 immunophenotypes suggestively related to IgAN, with 20 as risk factors and 18 as protective effects. Six immunophenotypes remained significant after Bonferroni correction: The percentage of CD25hi among T cells; the percentage of CD25hi CD45RA- CD4 not T regulatory (Treg) among T cells; the percentage of CD25hi CD45RA- CD4 not Treg within the CD4+ T cell population; CX3CR1 expression on monocytes; CD40 expression on monocytes; and CD64 expression on CD14+ CD16- monocytes. In the validation analysis of IgAN, CD3 expression on effector memory CD4+ T cells further confirmed the predisposing risk role of effector memory T cells in the development of IgAN. Additionally, the MR analysis demonstrated suggestive associations between 25 immunophenotypes and MN (8 risk factors and 17 protective factors), as well as between 22 immunophenotypes and NS (10 risk factors and 12 protective factors). Last, by intersecting the immunophenotypes showing suggestive associations with PGDs, we identified two common immunophenotypes shared by IgAN and MN, three by IgAN and NS, and one by MN and NS.

Conclusions

This genetic-level investigation uncovers causal associations between immunophenotypes and PGDs, providing valuable insights into the immunological underpinnings of PGDs. Our findings suggest potential targets for treatment strategies, thereby facilitating more personalized and effective therapeutic approaches in PGDs management.

Urinary interleukin 13 level in steroid sensitive and resistant nephrotic syndrome: a cross-sectional single center study

Nephrotic syndrome, the most common glomerular disease in pediatric population, is classified into two groups of steroid sensitive (SSNS) and resistant (SSRS). There is growing evidence on the role of T cells cytokines, including interleukin-13, in pathophysiology of nephrotic syndrome and steroid response. This study was a cross-sectional study conducted at Children's Medical Center Hospital in order to explore the relationship between urinary IL-13 levels and responsiveness to corticosteroid treatment. All children (1 to 15 years) referred from January 2021 to January 2022 diagnosed with nephrotic syndrome were included. Urine samples were collected during the initial phase or relapse of nephrotic syndrome, before the initiation of steroid or alternative treatments. Interleukin-13 levels in the urine were measured using the ELISA method. In this study, 83 cases of nephrotic syndrome were enrolled, of whom 30 (36.1%) were girls and 53 (63.9%) were boys. Out of the 83 cases, 63 (75.9%) were identified as SSNS and 20 (24.1%) as SRNS. There was no significant difference between the urinary interleukin-13 levels between SSNS and SRNS groups (P-value: 0.84). Sex (P-value: 0.598) and age (P-value: 0.704) also had no association with interleukin-13 levels. Further studies in larger population are recommended to better assess the potential of this biomarker to predict response to treatment. .

Optimal Trough Concentration of Tacrolimus in Pediatric Patients With Primary Nephrotic Syndrome

The trough concentration (C0) of tacrolimus in children with nephrotic syndrome (NS) has rarely been explored, so its target level was based on transplant research. This study aimed to determine the optimal tacrolimus C0 in NS children. Data from primary NS children treated with tacrolimus at Wuhan Children's Hospital in the last 10 years were retrospectively collected. According to the cutoff C0 analyzed by receiver-operator characteristics (ROC) analysis, patients were divided into very low- (< 4 ng/mL), low- (4-5 ng/mL), medium- (5-7 ng/mL), and high-concentration (7-10 ng/mL) groups. A total of 196 patients were enrolled for primary outcome analysis. Compared to medium-concentration group, only the very low-concentration group obtained significant inferior primary outcomes, including overall remission rate, relapse-free survival rate, and relapse rate at 6 months. For secondary outcomes, the very low-concentration group experienced more frequent treatment failure in 12 months, whereas the high-concentration group suffered a higher risk of adverse events than the medium-concentration group. For steroid-resistant NS, very low- and low-concentration groups required longer time to achieve remission compared to medium-concentration group. For steroid-sensitive NS, the very low-concentration group suffered a higher relapse frequency than medium-concentration group. Lastly, the dose of tacrolimus required for children with different CYP3A5 genotypes with or without Wuzhi capsules was analyzed. In conclusion, tacrolimus may be targeted to C0 of 4-7 ng/mL during the first 6 months in children with NS. For steroid-resistant NS, C0 of 5-7 ng/mL can achieve a rapid remission.

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.

To biopsy or not to biopsy a teenager with typical idiopathic nephrotic syndrome? Start steroids first

It is well known that minimal change disease (MCD) and focal segmental glomerulosclerosis are the most common histopathology findings in children with idiopathic nephrotic syndrome. Moreover, several studies demonstrated that MCD is associated with high steroid-responsiveness and a low incidence of kidney failure, suggesting that routine kidney biopsy is not warranted. Over time, the indications for performing a kidney biopsy have become increasingly stringent, aiming to limit unnecessary invasive procedures in the paediatric population. The most recent guidelines state that a kidney biopsy is not usually necessary at disease onset. Still, it should be performed in case of atypical features suggestive of systemic diseases or glomerulonephritis and in case of steroid-resistance, to assess the different differential diagnoses, regardless of patient age. Moreover, it has been shown that the best prognostic marker in childhood nephrotic syndrome is response to treatment and that kidney histology is not accurate in predicting prognosis. Furthermore, a kidney biopsy is not necessary to predict the relapsing course. Notably, kidney biopsy is an invasive procedure and may lead to significant complications. Finally, novel non-invasive biomarkers have been validated or are in the process of being approved to guide differential diagnoses and thus limit the need for kidney biopsies in patients with typical nephrotic syndrome. In the following sections, we aim to explain why initiating steroid treatment as the initial approach in teenagers with typical nephrotic syndrome is a reasonable strategy. Additionally, we explore how kidney biopsy indications may be alleviated in this population.

Case Report: Nephrotic syndrome as the primary manifestation of Alport syndrome in a Chinese pediatric patient

Background

Alport syndrome (AS) is a genetically heterogeneous disorder resulting from variants in genes coding for the alpha-3/4/5 chains of Collagen IV, leading to defective basement membranes in the kidney, cochlea, and eye. The clinical manifestations of AS vary in patients. Cases of childhood AS caused by COL4A3 presenting primarily with nephrotic syndrome (NS) are rarely reported. Here, we report a pediatric case presenting initially with NS attributed to AS caused by COL4A3.

Case presentation

An 11-year-old boy presented with hematuria and nephrotic range proteinuria. After excluding secondary causes, primary NS was considered. He was administered with prednisone (60 mg/day). The patient had not responded to treatment by the end of 4 weeks, so he was diagnosed with steroid-resistant NS. A renal biopsy showed granular and vacuolar degeneration of renal tubular epithelial cells, multifocal foam cell infiltration in the renal interstitium, and immunofluorescence indicated the absence of α3, α4, and α5 expression in the glomerular and tubular basement membrane, while Bowman's capsule expression was normal. Electron microscopy ultrastructural suggested variable basement membrane thickness, and partial tearing and web-like structures. Genetic testing revealed a heterozygous COL4A3 missense mutation c.3210 (exon 37)G>A(NM:000091). These findings are consistent with the diagnosis of AS. Prednisone was gradually tapered and enalapril maleate was initiated.

Conclusion

We have described a pediatric case of AS featuring NS as its primary manifestation. It is important to consider AS to be a diagnosis or differential diagnosis in patients who have NS with hematuria or steroid resistance.

Kinetic-pharmacodynamic model to predict post-rituximab B-cell repletion as a predictor of relapse in pediatric idiopathic nephrotic syndrome

Purpose

Rituximab has proven efficacy in children with idiopathic nephrotic syndrome (INS). However, vast majority of children inevitably experience relapse with B-cell repletion, necessitating repeat course of rituximab, which may increase the risk of adverse effects. The timing of additional dosing and optional dosing regimen of rituximab in pediatric patients with INS have yet to be determined. This study aimed to identify factors that influence disease relapse and B-cell repletion to provide tailored treatment.

Methods

LASSO and random survival forest were performed on 143 children to screen covariates which were then included in Cox regression model to determine the biomarkers of relapse and establish a nomogram. A kinetic-pharmacodynamic (K-PD) model was developed in 59 children to characterize the time course of CD19+ B-cell after rituximab treatment. Monte Carlo simulation was conducted to explore a mini-dose regimen with larger intervals.

Results

Nomogram contained 7 predictors of relapse including neutrophil-to-lymphocyte ratio, duration of B-cell depletion, duration of disease, urine immunoglobulin G to creatinine ratio, urine transferrin, duration of maintenance immunosuppressant and hemoglobin. As a direct PD indicator, each 1-month increase of duration of B-cell depletion decreased risk of relapse by 21.4% (HR = 0.786; 95% CI: 0.635-0.972; p = 0.026). The K-PD model predicted t1/2 (CV%) of rituximab and CD19+ B-cell to be 11.6 days (17%) and 173.3 days (22%), respectively. Immunoglobulin A is an important covariate of ED50. Simulation of a mini-dose regimen with larger intervals (three 150 mg every 2 monthly) indicted longer B-cell depletion time (>7 months) compared to standard regimen.

Conclusion

The nomogram indicated optimal infusion timing before relapse and the K-PD model provided tailored rituximab regimens for children with INS to reduce safety risks and financial burden.

The application of omalizumab in children with atopic diseases complicated by nephrotic syndrome: a case report

Nephrotic syndrome (NS) and atopic diseases are linked through shared immunological pathways, with allergic triggers often contributing to NS relapses, particularly in immunoglobulin E (IgE)-mediated pathways. Omalizumab, a humanized monoclonal antibody targeting free and cell-bound IgE, is commonly used in treating atopic diseases. We presented a pediatric case with a history of eczema, asthma, and recurrent atopic rhinitis, who first developed NS at age three, responding well to steroid therapy. The patient experienced four NS relapses, three of which were associated with significant atopic symptoms, elevated eosinophil counts, and increased IgE levels, suggesting allergic triggers. After the latest relapse achieved remission, steroid therapy was discontinued, and Omalizumab was initiated two months later. The patient received monthly subcutaneous Omalizumab (300 mg) with regular urine protein monitoring. To date, the patient has shown marked improvement in atopic symptoms, sustained NS control, and reduced steroid dependence. This case highlights the potential of Omalizumab in treating NS triggered by allergic reactions, further prospective pilot studies and randomized controlled trials are warranted to rigorously evaluate its efficacy and safety.

Causal association of circulating immune cells with nephrotic syndrome: evidence from a two-sample Mendelian randomization study

OBJECTIVE

Nephrotic syndrome, a debilitating manifestation of kidney disease, often arises from diverse glomerular disorders and is accompanied by notable comorbidities. Despite indications of an immunological etiology, the precise role of immune cells in its pathogenesis remains unclear. This study aimed to elucidate the causal relationships between circulating immune cell phenotypes and nephrotic syndrome using a rigorous bidirectional Mendelian randomization approach.

METHODS

We conducted a bidirectional Mendelian randomization analysis leveraging public genome-wide association studies (GWAS) datasets to investigate the causal links between 731 immune cell features and nephrotic syndrome. Our primary analysis employed inverse variance weighting (IVW), complemented by MR-Egger regression, simple model, weighted median method, and weighted model techniques to ensure robustness. Sensitivity analyses were performed to address potential biases arising from heterogeneity, horizontal pleiotropy, and single-nucleotide polymorphism (SNP) instability in nephrotic syndrome.

RESULTS

Among traits examined, 13 immune cell phenotypes were identified to have significant causal impacts on nephrotic syndrome (adjusted P >  < 0.05). Among these phenotypes, CD25 on unswitched memory B cell, CD25 on memory B cell, CD25 on CD24 + CD27 + B cell, CD25 on IgD-CD38-B cell, CD33dim HLA DR-Absolute Count, and CD127 on granulocyte emerged as causal risk factors, while seven circulating immune cell phenotypes, predominantly monocyte subsets, exhibited protective effects. Furthermore, the reverse Mendelian randomization analysis demonstrated significant effects of nephrotic syndrome on 27 immune phenotypes (P < 0.05).

CONCLUSION

The genetic predictions indicate that multiple circulating immune cell phenotypes, particularly CD25 on specific B-cell subsets, serve as independent risk factors for the onset and progression of nephrotic syndrome. Conversely, monocytes expressing specific phenotypes may exert protective effects against the development of nephrotic syndrome. These findings offer a novel therapeutic approach for the prevention and treatment of nephrotic syndrome.

Childhood idiopathic nephrotic syndrome: recent advancements shaping future guidelines

Childhood idiopathic nephrotic syndrome is an important pediatric kidney disease associated with significant morbidities and even mortality. Several guidelines have been developed to standardize the terminology and patient care among the pediatric nephrology community. Since the publication of these guidelines, there have been major breakthroughs in the disease management and the understanding of underlying pathogenesis through multi-omics investigations, including the identification of anti-nephrin autoantibodies, genetic susceptibility loci, and the pathogenic role of B cell subsets. In this educational review, we summarize the recent major advancements in idiopathic nephrotic syndrome and attempt to provide potential therapeutic approaches in both steroid-sensitive and steroid-resistant nephrotic syndrome that may shape future guideline development.

Incidence and risk factors for acute kidney injury in children with nephrotic syndrome: a meta-analysis

Background

Nephrotic syndrome (NS) is a prevalent kidney disease in children. Acute kidney injury (AKI) is a severe complication of NS and has the potential to be life-threatening.

Objective

The aim of this study was to analyze the prevalence and risk factors of AKI in children with NS, and to provide an evidence-based medical basis for the early identification of high-risk children in the clinic.

Methods

A comprehensive search was conducted in publicly available databases, namely PubMed, Embase, Web of Science, Scopus, and the Cochrane Library, covering the period from the inception of each database until May 2024. The analysis involved examining basic characteristics (age, sex), the concomitant diseases (hypertension, infections), NS disease characteristics (steroid susceptibility classification, pathologic classification), laboratory test (e.g., serum albumin), and the use of nephrotoxic drugs. Traditional and network meta-analyses were performed for analysis.

Results

A total of 11 studies were included in the analysis, revealing an incidence of AKI of 29% (95% CI: 23%-37%). The analysis of factors indicated that the age of NS onset [standardized mean difference (SMD): 0.31; 95% confidence interval (CI): 0.08, 0.54; p = 0.009], sex [odds ratio (OR): 1.49; 95% CI: 1.03, 2.16; p = 0.035], serum albumin level (SMD: -0.43; 95% CI: -0.85, -0.02; p = 0.041), response to steroid treatment (OR: 0.52; 95% CI: 0.33, 0.80; p = 0.003), infection (OR: 3.60; 95% CI: 1.91, 6.78; p < 0.001), hypertension (OR: 4.02; 95% CI: 2.94, 5.51; p < 0.001), and nephrotoxic drug application (OR: 4.43; 95% CI: 1.86, 10.53; p = 0.001), were all significantly associated with the incidence of AKI. Furthermore, the results of the network meta-analysis suggested that the pathologic type of minor glomerular abnormalities (MGA)/diffuse mesangial proliferation (DMP), the type of infrequent relapses (IFRNS)/steroid-sensitive NS (SSNS), and the use of diuretic medications were associated with a relatively low risk of AKI occurrence.

Conclusion

Factors upon admission of children with NS are associated with the onset of AKI. Emphasis should be placed on populations with a heightened risk of AKI in clinical practice. Further research is warranted to confirm the findings due to the limitations of this study.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42024571170, PROSPERO (CRD42024571170).

Exploration of the pathogenesis of nephrotic syndrome and traditional Chinese medicine intervention based on gut microbiota

Nephrotic syndrome (NS) represents a prevalent syndrome among various chronic kidney disease pathologies and is known for its higher severity and worse prognosis compared with chronic glomerulonephritis. Understanding its pathogenesis and identifying more effective treatment modalities have long been a concern of kidney specialists. With the introduction of the gut-kidney axis concept and the progress in omics technologies, alterations in the gut microbiota have been observed in primary and secondary NS. This link has been extensively researched in conditions such as diabetic nephropathy and immunoglobulin A (IgA) nephropathy. Thus, dysbiosis of the gut microbiota is seen as a crucial contributing factor in NS; however, there is a lack of comprehensive reviews that elucidate the changes in the gut microbiota across different NS conditions and that describe its mechanistic role in the disease. Moreover, serving as an innate regulator of the gut microbiota, traditional Chinese medicine (TCM) has the potential to exert a profound impact on the expression of inflammation-promoting agents, decreasing the levels of endotoxins and uremic toxins. In addition, it strengthens the stability of the intestinal barrier while controlling the metabolic function of the body through its efficient modulation of the gut microbiota. This intricate process yields far-reaching consequences for NS.

Prediction Model and Decision Analysis for Early Recognition of SDNS/FRNS in Children

Purpose

This study identified factors that identification of progression-predicting utility from steroid-sensitive nephrotic syndrome(SSNS) to steroid-dependent or frequently relapsing nephrotic syndrome (SDNS/FRNS) in patients and developed a corresponding predictive model.

Patients and Methods

This retrospective study analyzed clinical data from 756 patients aged 1 to 18 years, diagnosed with SSNS, who received treatment at the Department of Nephrology, Children's Hospital of Chongqing Medical University, between November 2007 and May 2023. We developed a shrinkage and selection operator (LASSO) - logistic regression model, which was visualized using a nomogram. The model's performance, validity, and clinical utility were evaluated through receiver operating characteristic curve analysis, confusion matrix, calibration plot, and decision curve analysis.

Results

The platelet-to-lymphocyte ratio (PLR) was identified as an independent risk factor for progression, with an odds ratio (OR) of 1.01 (95% confidence interval (CI) = 1.01-1.01, p = 0.009). Additionally, other significant factors included the time for urinary protein turned negative (OR = 1.17, 95% CI = 1.12-1.23, p < 0.001), estimated glomerular filtration rate(eGFR) (OR = 0.99, 95% CI = 0.98-0.99, p < 0.001), low-density lipoprotein (OR = 0.90, 95% CI = 0.83-0.97, p = 0.006), thrombin time (OR = 1.22, 95% CI = 1.07-1.39, p = 0.003), and neutrophil absolute counts (OR = 1.10, 95% CI = 1.02-1.18, p = 0.009). The model's performance was assessed through internal validation, yielding an area under the curve of 0.78 (0.73-0.82) for the training set and 0.81 (0.75-0.87) for the validation set.

Conclusion

PLR, eGFR, the time for urinary protein turned negative, low-density lipoprotein, thrombin time, and neutrophil absolute counts may be effective predictors for identifying SSNS patients at risk of progressing to SDNS/FRNS. These findings offer valuable insights for early detection and support the use of precision medicine strategies in managing SDNS/FRNS.

Circulating RAC1 contributed to steroid-sensitive nephrotic syndrome: Mendelian randomization, single-cell RNA-sequencing, proteomic, and experimental evidence

OBJECTIVES

The small GTPase Rac1 (RAC1) has been linked to podocyte disorders and steroid-sensitive nephrotic syndrome (SSNS). The aim of this study was to explore and validate the potential causal association between circulating RAC1 and SSNS.

METHODS

The association between circulating RAC1 and SSNS at both gene expression and proteomic levels was investigated using Mendelian randomization analysis, and further validated by single-cell RNA-sequencing, proteomic analysis, and experimental studies. The genetic instruments comprised cis-expression quantitative trait loci (cis-eQTLs) associated with RAC1 gene expression and protein QTLs correlated with plasma RAC1 protein levels. Causal associations were estimated utilizing the inverse variance weighted and MR-PRESSO methods. Validation of RAC1 expression was conducted through single-cell RNA-sequencing of peripheral blood mononuclear cells from patients with SSNS and healthy controls. Proteomic analysis was performed among patients with minimal change nephrotic syndrome. Experimental validation was conducted using a puromycin aminonucleoside (PAN)-induced nephrosis model.

RESULTS

Increased expression of RAC1 was associated with a higher risk of SSNS (gene expression level: odds ratio [OR], 1.53; 95% confidence interval [CI], 1.02-2.28; protein level: OR, 1.82; 95% CI, 1.05-3.17). The results of MR-PRESSO were consistent (gene expression level: OR, 1.49; 95% CI, 1.17-1.92; protein level: OR, 1.81; 95% CI, 1.16-2.85). Single-cell RNA sequencing and proteomic analysis confirmed elevated RAC1 expression in patients with SSNS compared to healthy controls. Experimental data further supported increased RAC1 expression in PAN-induced nephropathy.

CONCLUSIONS

Increased expression of RAC1 might be causally associated with SSNS, suggesting that targeting RAC1 might represent a potential therapeutic strategy for SSNS.

Pediatric contributions and lessons learned from the NEPTUNE cohort study

Primary glomerular diseases are rare entities. This has hampered efforts to better understand the underlying pathobiology and to develop novel safe and effective therapies. NEPTUNE is a rare disease network that is focused on patients of all ages with minimal change disease, focal segmental glomerulosclerosis, and membranous nephropathy. It is a longitudinal cohort study that collects detailed demographic, clinical, histopathologic, genomic, transcriptomic, and metabolomic data. The goal is to develop a molecular classification for these disorders that supersedes the traditional pathological features-based schema. Pediatric patients are important contributors to this ongoing project. In this review, we provide a snapshot of the children and adolescents enrolled in NEPTUNE and summarize some key observations that have been made based on the data accumulated during the study. In addition, we describe the development of NEPTUNE Match, a program that aims to leverage the multi-scalar information gathered for each individual patient to provide guidance about potential clinical trial participation based on the molecular characterization and non-invasive biomarker profile. This represents the first organized effort to apply principles of precision medicine to the treatment of patients with primary glomerular disease. NEPTUNE has proven to be an invaluable asset in the study of glomerular diseases in patients of all ages including children and adolescents.

Characterization of Herpesviridae Family Members, BK Virus, and Adenovirus in Children and Adolescents with Nephrotic Syndrome

Since the significance of viral infections in children and adolescents with nephrotic syndrome (NS) is yet to be defined, this study intended to estimate the occurrence, pattern, and outcomes of some DNA viral infections in children with NS.

METHODS

A prospective study was conducted to determine the genome identification of the viruses Epstein-Barr (EBV), human cytomegalovirus (HCMV), human herpesvirus 6 (HHV-6 type A and type B) and 7 (HHV-7), polyomavirus (BKV), and human adenovirus (HAdV) in plasma and urine samples of pediatric patients with NS.

RESULTS

A total of 35 patients aged 1 to 18 years with NS and under immunosuppressant drugs participated in the study. Plasma and urine samples were collected at regular intervals during a median follow-up of 266 days (range 133-595), and DNA was analyzed to detect the selected DNA viruses. Eleven patients (31.4%) had active virus infections, and patterns were classified as coinfection, recurrent, and consecutive. Of these, six patients (54.5%) presented viral coinfection, six (54.5%) viral recurrence, and seven patients (63.3%) had viral consecutive infection. Ten of the eleven patients with active infection had a proteinuria relapse (91%) and eight (72.7%) were hospitalized (p = 0.0022). Active HCMV infection was the most frequent infection and was observed in six patients (54.5%), three of the eleven patients (27.2%) had suspected HCMV disease in the gastrointestinal tract, and one had HHV-7 coinfection. The frequency of other infections was: 9% for HHV-6, 45.5% for BKV, 27.3% for HHV-7, 18.2% for EBV, and 18.2% for HAdV.

CONCLUSION

viral infections, especially HCMV, can be an important cause of morbidity and nephrotic syndrome relapse in children.

Levamisole in childhood idiopathic nephrotic syndrome: new promises, and advocacy for global access

In the current issue of Kidney International, Sinha et al. present data from an open-label, noninferior, randomized controlled trial comparing 12-months of alternate-day prednisolone, given daily during infection, versus levamisole, in children with frequently relapsing or steroid-dependent nephrotic syndrome. This study suggests that both of these strategies are efficacious and safe. Results of this study should redefine the role of levamisole in future guidelines, and a call for global availability of levamisole should be advocated.

Effects of High-Dose Cyclophosphamide on Ultrastructural Changes and Gene Expression Profiles in the Cardiomyocytes of C57BL/6J Mice

The pathogenesis of cyclophosphamide (CY)-induced cardiotoxicity remains unknown, and methods for its prevention have not been established. To elucidate the acute structural changes that take place in myocardial cells and the pathways leading to myocardial damage under high-dose CY treatments, we performed detailed pathological analyses of myocardial tissue obtained from C57BL/6J mice subjected to a high-dose CY treatment. Additionally, we analysed the genome-wide cardiomyocyte expression profiles of mice subjected to the high-dose CY treatment. Treatment with CY (400 mg/kg/day intraperitoneally for two days) caused marked ultrastructural aberrations, as observed using electron microscopy, although these aberrations could not be observed using optical microscopy. The expansion of the transverse tubule and sarcoplasmic reticulum, turbulence in myocardial fibre travel, and a low contractile protein density were observed in cardiomyocytes. The high-dose CY treatment altered the cardiomyocyte expression of 1210 genes (with 675 genes upregulated and 535 genes downregulated) associated with cell-cell junctions, inflammatory responses, cardiomyopathy, and cardiac muscle function, as determined using microarray analysis (|Z-score| > 2.0). The expression of functionally important genes related to myocardial contraction and the regulation of calcium ion levels was validated using real-time polymerase chain reaction analysis. The results of the gene expression profiling, functional annotation clustering, and Kyoto Encyclopedia of Genes and Genomes pathway functional-classification analysis suggest that CY-induced cardiotoxicity is associated with the disruption of the Ca2+ signalling pathway.

A novel flow cytometry panel to identify prognostic markers for steroid-sensitive forms of idiopathic nephrotic syndrome in childhood

Introduction

The clinical evolution of steroid-sensitive forms of pediatric idiopathic nephrotic syndrome (INS) is highly heterogeneous following the standard treatment with prednisone. To date, no prognostic marker has been identified to predict the severity of the disease course starting from the first episode.

Methods

In this monocentric prospective cohort study we set up a reproducible and standardized flow cytometry panel using two sample tubes (one for B-cell and one for T-cell subsets) to extensively characterized the lymphocyte repertoire of INS pediatric patients. A total of 44 children with INS at disease onset were enrolled, sampled before and 3 months after standard induction therapy with prednisone and followed for 12 months to correctly classify their disease based on relapses. Age-matched controls with non immune-mediated renal diseases or with urological disorders were also enrolled. Demographical, clinical, laboratory and immunosuppressive treatment data were registered.

Results

We found that children with INS at disease onset had significantly higher circulating levels of total CD19+ and specific B-cell subsets (transitional, mature-naïve, plasmablasts/plasmacells, CD19+CD27+, unswitched, switched and atypical memory B cells) and reduced circulating levels of Tregs, when compared to age-matched controls. Prednisone therapy restored most B- and T-cell alterations. When patients were subdivided based on disease relapse, relapsing patients had significantly more transitional, CD19+CD27+ memory and in particular unswitched memory B cells at disease onset, which were predictive of a higher risk of relapse in steroid-sensitive patients by logistic regression analysis, irrespective of age. In accordance, B-cell dysregulations resulted mainly associated with steroid-dependence when patients were stratified in different disease severity forms. Of note, Treg levels were reduced independently from the disease subgroup and were not completely normalized by prednisone treatment.

Conclusion

We have set up a novel, reproducible, disease-specific flow cytometry panel that allows a comprehensive characterization of circulating lymphocytes. We found that, at disease onset, relapsing patients had significantly more transitional, CD19+CD27+ memory and unswitched memory B cells and those who are at higher risk of relapse had increased circulating levels of unswitched memory B cells, independently of age. This approach can allow prediction of clinical evolution, monitoring of immunosuppression and tailored treatment in different forms of INS.

Shear wave elastography of kidneys in children: utility in distinguishing steroid-resistant and steroid-sensitive nephrotic syndrome

PURPOSE

To assess the renal elasticity values using (SWE) and correlate the values with steroid sensitivity to distinguish between steroid-resistant nephrotic syndrome (SRNS) and steroid-sensitive nephrotic syndrome (SSNS) in children.

METHODS

In this IRB-approved cross-sectional study, 83 children (4-14 years) diagnosed with nephrotic syndrome were included from July 2021 to December 2022. SWE measurements were done for each kidney's upper pole, interpolar region, and lower pole. Mean as well as median SWE were calculated. Correlation of the renal stiffness values was done with different laboratory findings (blood urea, serum creatinine, 24 h urine protein, serum albumin, and serum cholesterol), the grayscale findings (cortical echogenicity, and corticomedullary differentiation), and the final diagnosis of SRNS and SSNS. The statistical tests were done at a significance level of α = 0.05.

RESULTS

The median (IQR) overall SWE of kidneys was higher in SRNS group 12.64 (8.4-19.68) kPa than SSNS group 9.87 (8.20-12.56) kPa. The difference was significant (p = 0.004). At a cut-off of ≥ 10.694 kPa (AUROC- 0.641), the overall SWE predicted SRNS group with a sensitivity of 70% and a specificity of 63%. A significant correlation (p < 0.05) was found between the SWE and 24-h urine protein, cortical echogenicity, and corticomedullary differentiation in SSNS, while only between SWE and corticomedullary differentiation in SRNS.

CONCLUSION

The mean SWE was higher in children with SRNS. While SWE has potential to differentiate SSNS from SRNS, a different study design where SWE is performed at presentation is needed for confirmation.