Triggers of relapse in steroid-dependent and frequently relapsing nephrotic syndrome

The association between dental caries and steroid-sensitive nephrotic syndrome in children

BACKGROUND

Pathogenesis and relapse of steroid-sensitive nephrotic syndrome (SSNS) are primarily associated with infection. Dental caries is the most common chronic progressive oral infection in children. However, clinical studies of SSNS combined with dental caries in children are rare.

METHODS

In our retrospective cohort study from January 2021 to June 2022, 145 children with SSNS were included in the baseline analysis and 105 in the follow-up analysis. The follow-up period was 1 year. The primary study endpoints were the relapse-free period and frequently relapsing nephrotic syndrome (FRNS). Secondary endpoints included the number and triggers of relapses and concomitant medications.

RESULTS

The median age was 5.5 years, with a caries rate of 60.7%, the mean DMFT/dmft was 3.86, and the caries filling rate was 1.6%. Except for the lower proportion of high household income and high parental education observed in the caries group, no statistical differences were found when comparing the other baseline data with the non-caries group. The caries group had a shorter relapse-free period and a lower 1-year cumulative relapse-free survival rate (HR = 1.90, 95% CI 1.17-3.09, P = 0.009). Univariate regression analysis showed caries associated with FRNS (OR = 2.714, 95% CI 1.021-7.219, P = 0.045), but the correlation no longer remained in the multivariate analysis. Additionally, seven cases of caries-derived pulpal periapical inflammation triggered SSNS relapses. The caries group had more infection triggers and concomitant medication use.

CONCLUSION

Dental caries and relapse of SSNS are potentially associated, but careful evaluation is needed.

"Idiopathic" minimal change nephrotic syndrome: a podocyte mystery nears the end

The discovery of zinc fingers and homeoboxes (ZHX) transcriptional factors and the upregulation of hyposialylated angiopoietin-like 4 (ANGPTL4) in podocytes have been crucial in explaining the cardinal manifestations of human minimal change nephrotic syndrome (MCNS). Recently, uncovered genomic defects upstream of ZHX2 induce a ZHX2 hypomorph state that makes podocytes inherently susceptible to mild cytokine storms resulting from a common cold. In ZHX2 hypomorph podocytes, ZHX proteins are redistributed away from normal transmembrane partners like aminopeptidase A (APA) toward alternative binding partners like IL-4Rα. During disease relapse, high plasma soluble IL-4Rα (sIL-4Rα) associated with chronic atopy complements the cytokine milieu of a common cold to displace ZHX1 from podocyte transmembrane IL-4Rα toward the podocyte nucleus. Nuclear ZHX1 induces severe upregulation of ANGPTL4, resulting in incomplete sialylation of part of the ANGPTL4 protein, secretion of hyposialylated ANGPTL4, and hyposialylation-related injury in the glomerulus. This pattern of injury induces many of the classic manifestations of human minimal change disease (MCD), including massive and selective proteinuria, podocyte foot process effacement, and loss of glomerular basement membrane charge. Administration of glucocorticoids reduces ANGPTL4 upregulation, which reduces hyposialylation injury to improve the clinical phenotype. Improving sialylation of podocyte-secreted ANGPTL4 also reduces proteinuria and improves experimental MCD. Neutralizing circulating TNF-α, IL-6, or sIL-4Rα after the induction of the cytokine storm in Zhx2 hypomorph mice reduces albuminuria, suggesting potential new therapeutic targets for clinical trials to prevent MCD relapse. These studies collectively lay to rest prior suggestions of a role of single cytokines or soluble proteins in triggering MCD relapse.

Incidence of idiopathic nephrotic syndrome during the Covid-19 pandemic in the Paris area (France) and in the Netherlands

BACKGROUND

The aetiology of idiopathic nephrotic syndrome (INS) remains partially unknown. Viral infections have been associated with INS onset. Since we observed fewer first onset INS cases during the Covid-19 pandemic, we hypothesised that lower INS incidence was the result of lockdown measures. Therefore, the aim of this study was to evaluate the incidence of childhood INS before and during the COVID-19 pandemic in two independent European INS cohorts.

METHODS

Children with new INS in the Netherlands (2018-2021) and Paris area (2018-2021) were included. We estimated incidences using census data for each region. Incidences were compared using two proportion Z-tests.

RESULTS

A total of 128 and 324 cases of first onset INS were reported in the Netherlands and Paris area, respectively, corresponding to an annual incidence of 1.21 and 2.58 per 100,000 children/year. Boys and young children (< 7 years) were more frequently affected. Incidence before and during the pandemic did not differ. When schools were closed, incidence was lower in both regions: 0.53 vs. 1.31 (p = 0.017) in the Netherlands and 0.94 vs. 2.63 (p = 0.049) in the Paris area. During peaks of hospital admissions for Covid-19, no cases were reported in the Netherlands or Paris area.

CONCLUSIONS

Incidence of INS before and during the Covid-19 pandemic was not different, but when schools were closed during lockdown, incidence was significantly lower. Interestingly, incidences of other respiratory viral infections were also reduced as was air pollution. Together, these results argue for a link between INS onset and viral infections and/or environmental factors. A higher resolution version of the Graphical abstract is available as Supplementary information.

Kidney involvement in children during the SARS-CoV-2 Omicron variant pandemic

BACKGROUND

As the coronavirus disease-2019 (COVID-19) pandemic continues, driven by the Omicron variant, infection rates in children have recently rapidly surged compared with previous years. We aimed to investigate the presentation of kidney involvement in children after Omicron variant severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection.

METHODS

We retrospectively reviewed the medical records of pediatric patients who presented with kidney disease with a temporal relationship with COVID-19 between January and August 2022 in a single tertiary center in Korea.

RESULTS

Fifteen children presented with kidney involvement after Omicron variant infection, with a median age of 10.6 (6.8-18.3) years. None of the patients exhibited severe respiratory symptoms apart from cough and sore throat. The median time from infection to renal symptom onset was 3 (0-49) days. Among 10 patients with underlying kidney disease, six had previously been diagnosed with nephrotic syndrome (NS) that relapsed after COVID-19 infection, two with immunoglobulin A nephropathy (IgAN) experienced transient gross hematuria (GHU) with or without acute kidney injury (AKI), and two with kidney transplantation presented with AKI. Of the five patients without underlying kidney disease, one patient had NS, and the other four patients had GHU and proteinuria (PU), of whom one was eventually diagnosed with Henoch Shönlein Purpura nephritis (HSPN), and one with rhabdomyolysis. The seven patients with NS (1 new-onset, 6 relapsed) had uneventful remission with corticosteroid therapy. Apart from one patient with new-onset HSPN, GHU and PU resolved spontaneously in all affected patients, and AKI also resolved with supportive care.

CONCLUSIONS

Kidney involvement subsequent to Omicron variant COVID-19 exhibited various, but mostly mild manifestations in children.

Cytokine storm-based mechanisms for extrapulmonary manifestations of SARS-CoV-2 infection

Viral illnesses like SARS-CoV-2 have pathologic effects on nonrespiratory organs in the absence of direct viral infection. We injected mice with cocktails of rodent equivalents of human cytokine storms resulting from SARS-CoV-2/COVID-19 or rhinovirus common cold infection. At low doses, COVID-19 cocktails induced glomerular injury and albuminuria in zinc fingers and homeoboxes 2 (Zhx2) hypomorph and Zhx2+/+ mice to mimic COVID-19-related proteinuria. Common Cold cocktail induced albuminuria selectively in Zhx2 hypomorph mice to model relapse of minimal change disease, which improved after depletion of TNF-α, soluble IL-4Rα, or IL-6. The Zhx2 hypomorph state increased cell membrane to nuclear migration of podocyte ZHX proteins in vivo (both cocktails) and lowered phosphorylated STAT6 activation (COVID-19 cocktail) in vitro. At higher doses, COVID-19 cocktails induced acute heart injury, myocarditis, pericarditis, acute liver injury, acute kidney injury, and high mortality in Zhx2+/+ mice, whereas Zhx2 hypomorph mice were relatively protected, due in part to early, asynchronous activation of STAT5 and STAT6 pathways in these organs. Dual depletion of cytokine combinations of TNF-α with IL-2, IL-13, or IL-4 in Zhx2+/+ mice reduced multiorgan injury and eliminated mortality. Using genome sequencing and CRISPR/Cas9, an insertion upstream of ZHX2 was identified as a cause of the human ZHX2 hypomorph state.

Can Oral Zinc Supplementation Reduce Relapses in Childhood Steroid-Sensitive Nephrotic Syndrome? A Systematic Review

Introduction

Frequent relapses and steroid dependence are common treatment challenges of steroid-sensitive nephrotic syndrome (SSNS) in children. Acute respiratory infection (ARI) is the most frequently reported trigger of relapse. Given the role of zinc supplementation in preventing ARI, some studies show that this targeted intervention may reduce relapses in childhood SSNS.

Aim

This systematic review aimed to determine if oral zinc supplementation can significantly reduce relapses in this disease.

Methods

We searched the PubMed and Google Scholar electronic databases for interventional and observational analytical studies without limiting their year or language of publication. We selected studies with primary data that met our inclusion criteria, screened their titles and abstracts, and removed duplicates. We used a preconceived structured form to extract data items from selected studies and conducted a quality assessment of randomized controlled trials (RCTs) and non-randomized studies with the Cochrane collaboration tool and the Newcastle Ottawa Scale, respectively. We qualitatively synthesized the extracted data to validate the review's objective.

Results

Eight full-text articles were selected, comprising four RCTs and four observational analytical studies. Two of the RCTs had a high risk of bias in three parameters of the Cochrane collaboration tool, while three non-randomized studies had low methodological quality. A total of 621 pediatric patients with SSNS were investigated in the eight studies: six participants dropped out in one study. Three RCTs indicate that zinc supplementation may lead to sustained remission or reduction in relapse rate. Similarly, three observational analytical studies suggest a significant relationship between reduced serum zinc levels and disease severity.

Conclusion

Despite the association of zinc deficiency with increased morbidity in SSNS and the reduction of relapse rates with zinc supplementation, there is no robust evidence to recommend its use as a therapeutic adjunct. We recommend more adequately-powered RCTs to strengthen the current evidence.

Relapse rate in children with nephrotic syndrome during the SARS-CoV-2 pandemic

BACKGROUND

Viral upper respiratory tract infections trigger nephrotic syndrome relapses. Few data exist on the impact of the SARS-CoV-2 pandemic on the risk of relapse in children with idiopathic nephrotic syndrome (INS).

METHODS

In a Belgian and Italian cohort of children with INS, we performed a retrospective analysis on the number and duration of relapses observed in 3 different periods in 2020: first COVID period, February 15-May 31; second COVID period, June 1-September 14; third COVID period, September 15-December 31. Relapse rates were compared to those of the previous 5 years (PRECOVID period). For the years 2019 and 2020, all causes and INS relapse-related hospitalizations were recorded. Hospitalizations and deaths due to SARS-CoV-2 infection were also recorded. In the Belgian cohort, SARS-CoV-2 serologies were performed.

RESULTS

A total of 218 patients were enrolled, and 29 (13.3%) were diagnosed with new-onset INS during the COVID period. Relapse rates per 1000 person-days were as follows: 3.2 in the PRECOVID period, 2.7 in the first COVID period, 3.3 in the second COVID period, and 3.0 in the third COVID period. The incidence rate ratio for the total COVID period was 0.9 (95%CI 0.76 to 1.06; P = 0.21) as compared to the PRECOVID period. During 2020, both the proportion of patients hospitalized for recurrence (14.2% vs. 7.6% in 2019; P = 0.03) and the rate of hospitalization for recurrence (IRR 1.97 (95%CI 1.35 to 2.88); P = 0.013) were higher compared to 2019. In December 2020, anti-SARS-CoV-2 antibodies were detected in 31% of the Belgian cohort. Patients with positive and negative SARS-CoV-2 serology did not differ significantly in relapse rate (2.4 versus 4.2 per 1000 person-days). The number of new INS cases remained similar between 2020, 2019, and 2018.

CONCLUSION

The first year of the SARS-CoV-2 pandemic did not significantly affect the relapse rate in children with INS. No serious infections were reported in this population of immunosuppressed patients. A higher resolution version of the Graphical abstract is available as Supplementary information.

Epidemiology, severity, and risk of SARS-CoV-2-related relapse in children and young adults affected by idiopathic nephrotic syndrome: a retrospective observational cohort study

BACKGROUND

Children with underlying kidney diseases display a mild course of SARS-CoV-2 infection, but they only accounted for a minority of cases until the spread of the Omicron variant. Nonetheless, idiopathic nephrotic syndrome (INS) has been advocated as a predictor of worse outcome.

METHODS

We investigated the spread, severity, and risk of relapse related to SARS-CoV-2 infection among children with INS. The incidence and characteristics of SARS-CoV-2 infections, immunosuppression, and vaccination status were retrospectively collected from the beginning of the pandemic to May 31, 2022.

RESULTS

We enrolled 176 patients (73 females, median age 10.22 years); 28 had a steroid-resistant disease, and 108 (61.4%) were on immunosuppressive therapy. Sixty-one (34.7%) patients reported a SARS-CoV-2 infection, with incidence peaking between December 2021 and January 2022. No hospitalization or deaths were reported, and symptoms were absent or mild. The rate of SARS-CoV-2 infection was similar in children with and without immunosuppression (33.8% vs 35.2%; p = 0.85). None of the 38 immunosuppressed patients discontinued the therapy, but they had a longer time to negativization (13.31 vs. 10.04 days; p = 0.03). Proteinuria was detected in 7 patients, but only one had a relapse requiring steroid therapy, with prompt remission and a mild course.

CONCLUSIONS

After the spread of the Omicron variant, the rate of SARS-CoV-2 infection in children with INS was much higher than previously reported. In this large cohort, symptoms were mild, even in immunosuppressed patients and those with proteinuria. During the infection, transient proteinuria was common with a low rate of relapses. A higher resolution version of the Graphical abstract is available as Supplementary information.

Therapeutic trials in difficult to treat steroid sensitive nephrotic syndrome: challenges and future directions

Steroid sensitive nephrotic syndrome is a common condition in pediatric nephrology, and most children have excellent outcomes. Yet, 50% of children will require steroid-sparing agents due to frequently relapsing disease and may suffer consequences from steroid dependence or use of steroid-sparing agents. Several steroid-sparing therapeutic agents are available with few high quality randomized controlled trials to compare efficacy leading to reliance on observational data for clinical guidance. Reported trials focus on short-term outcomes such as time to first relapse, relapse rates up to 1-2 years of follow-up, and few have studied long-term remission. Trial designs often do not consider inter-individual variability, and differing response to treatments may occur due to heterogeneity in pathogenic mechanisms, and genetic and environmental influences. Strategies are proposed to improve the quantity and quality of trials in steroid sensitive nephrotic syndrome with integration of biomarkers, novel trial designs, and standardized outcomes, especially for long-term remission. Collaborative efforts among international trial networks will help move us toward a shared goal of finding a cure for children with nephrotic syndrome.

Machine learning models for predicting steroid-resistant of nephrotic syndrome

Background

In the absence of effective measures to predict steroid responsiveness, patients with nonhereditary steroid-resistant nephrotic syndrome (SRNS) have a significantly increased risk of progression to end-stage renal disease. In view of the poor outcomes of SRNS, it is urgent to identify the steroid responsiveness of idiopathic nephrotic syndrome (INS) early.

Methods

To build a prediction model for SRNS, we collected 91 subjects; 57 of them had steroid-sensitive nephrotic syndrome, and the others had SRNS. For each subject, 87 clinical variables were measured. In general, only a small part of these variables is informative to SRNS. Thus, we proposed a new variable selection framework including a penalized regression approach (named MLR+TLP) to select variables having a linear effect on the SRNS and a nonparametric screening method (MAC) to select variables having a nonlinear marginal (joint) effect on the SRNS. Thereafter, considering the correlation between selected clinical variables, we used a stepwise method to build our final model for predicting SRNS. In addition, a statistical testing procedure is proposed to test the overfitting of the proposed model.

Results

Twenty-six clinical variables were selected to be informative to SRNS, and an SVM model was built to predict SRNS with a leave-one-out cross-validation (LOO-CV) accuracy of 95.2% (overfitting p value<0.005). To make the model more useful, we incorporate prior medical information into the model and consider the correlation between selected variables. Then, a reduced SVM model including only eight clinical variables (erythrocyte sedimentation rate, urine occult blood, percentage of neutrophils, immunoglobulin A, cholesterol, vinculin autoantibody, aspartate aminotransferase, and prolonged prothrombin time) was built to have a LOO-CV accuracy of 92.8% (overfitting p value<0.005). The validation cohort showed that the reduced model obtained an accuracy of 94.0% (overfitting p value<0.005), with a sensitivity of 90.0% and a specificity of 96.7%. Notably, vinculin autoantibody is the only podocyte autoantibody included in this model. It is linearly related to steroid responsiveness. Finally, our model is freely available as a user-friendly web tool at https://datalinkx.shinyapps.io/srns/.

Conclusion

The SRNS prediction model constructed in this study comprehensively and objectively evaluates the internal conditions and disease status of INS patients and will provide scientific guidance for selecting treatment methods for children with nonhereditary SRNS.

Rates of idiopathic childhood nephrotic syndrome relapse are lower during the COVID-19 pandemic

BACKGROUND

Infections are thought to be primarily responsible for triggering relapse in children with steroid-sensitive nephrotic syndrome (NS). The COVID-19 pandemic promoted physical distancing, facial mask wearing, and greater attention to infection-prevention measures resulting in decreased transmission of infections. We hypothesized there would also be a decreased rate of NS relapse during this period.

METHODS

We conducted a single-center retrospective chart review of children with steroid-sensitive NS. Demographics, rate of relapses, and rate of hospitalizations were collected for a baseline pre-pandemic period (BPP) and for the social distancing period during the pandemic (SDP).

RESULTS

One hundred twenty-two children with primary steroid-sensitive NS were identified and 109 were followed for the duration of the study period. The paired rate of relapse per subject per year was significantly lower during the SDP (0.6 relapses per subject per year ± 1 SD) compared to the BPP (1.0 relapses per subject per year ± 0.9 SD), P &lt; 0.01. A subgroup of 32 subjects who were newly diagnosed with NS during the BPP similarly had significantly fewer relapses during the SDP (0.8 ± 1 SD) than during the BPP (1.4 ± 1 SD), P = 0.01.

CONCLUSIONS

Our results support the hypothesis of lower rates of NS relapse and hospitalizations during social distancing for all subjects in our cohort and a subgroup of those newly diagnosed. Lower relapse rates were likely attributable to decreased transmission of infections and greater attention to infection prevention. A higher resolution version of the Graphical abstract is available as Supplementary information.

Establishment of relapse risk model and multivariate logistic regression analysis on risk factors of relapse in children with primary nephrotic syndrome

This study aimed to investigate relapse risk factors in children with primary nephrotic syndrome (PNS) for prevention and early intervention via logistic regression. One hundred thirty-seven children with PNS were enrolled in this study. Clinical variables were analyzed by single-factor and multiple regression analysis to establish the regression equation. The predictive ability of the regression equation was investigated by the receiver operating characteristic curve (ROC). Files of 17 patients were lost, and 120 patients were enrolled finally in the study, among whom 55 cases (45.8%) had frequently relapsed. Single-factor analysis and multiple regression analysis revealed that concurrent infection on first onset, irregular glucocorticoid therapy, severe hypoalbuminemia, and persistent severe hyperlipidemia were the significant risk factors for frequent relapse on PNS (P < .05), among which infection remained to be the main inductive factor. Among the 4 indicators, serum albumin had the best diagnostic efficacy based on the area under the ROC curve (0.933), sensitivity (89.09%), and specificity (81.54%). The area under curve, sensitivity, and specificity for the combined diagnostic model of the 4 indices were 97.8%, 98.18%, and 90.77%, respectively, which had good predictive power for the relapse of patients. Concurrent infection, irregular glucocorticoid therapy, severe hypoalbuminemia, and persistent severe hyperlipemia were all the risk factors for PNS relapse. The established logistic regression model based on these factors above is reliable for predicting frequent PNS relapse. Much attention should be paid to these critical factors, and early intervention should be taken to reduce the incidence of relapse.

Infectious complications in children with nephrotic syndrome: Can they be prevented?

Background

Sixty percent of children with nephrotic syndrome have frequently relapsing or steroid-dependent course. Serious infections like peritonitis, cellulitis, pneumonia etc. and anasarca with reduced urine output and complications there of including acute kidney injury and thromboembolism contribute significantly to morbidity and mortality in these children.

Methods

Questionnaire-based module to study infectious complications in children with nephrotic syndrome was circulated through survey monkey portal to paediatric nephrologists in our country. Twenty-two responded. Forty percent said that they saw patients with severe infections once a month. Fish bone analysis conducted on such patients reporting to our centre over next 3 months revealed that only 22% regularly monitored urine protein by dipstick. We proposed that reduction in time to report relapse by regularly monitoring urine protein could reduce complications in these children. Six urine protein dipsticks were handed over to patients who presented >7 days since relapse or with severe infection or anasarca in the last 1 year. These children were followed up for the next 1 year and given six more urine dipsticks every 3 months.

Results

Twenty-three patients were given urine protein dipsticks. Nine of them had 12 severe complications in the previous 6 months. None had any serious infections/anasarca on follow-up. Sixteen new patients had 14 serious complications in this time.

Conclusions

Early detection of relapse by home monitoring of urine protein by dipsticks was effective in significantly reducing the number of patients with severe infections and anasarca with reduced urine output.

CyTOF-Enabled Analysis Identifies Class-Switched B Cells as the Main Lymphocyte Subset Associated With Disease Relapse in Children With Idiopathic Nephrotic Syndrome

B cell depleting therapies permit immunosuppressive drug withdrawal and maintain remission in patients with frequently relapsing nephrotic syndrome (FRNS) or steroid–dependent nephrotic syndrome (SDNS), but lack of biomarkers for treatment failure. Post-depletion immune cell reconstitution may identify relapsing patients, but previous characterizations suffered from methodological limitations of flow cytometry. Time-of-flight mass cytometry (CyTOF) is a comprehensive analytic modality that simultaneously quantifies over 40 cellular markers. Herein, we report CyTOF-enabled immune cell comparisons over a 12-month period from 30 children with SDNS receiving B cell depleting therapy who either relapsed (n = 17) or remained stable (n = 13). Anti-CD20 treatment depleted all B cells subsets and CD20 depleting agent choice (rituximab vs ofatumumab) did not affect B cell subset recovery. Despite equal total numbers of B cells, 5 subsets of B cells were significantly higher in relapsing individuals; all identified subsets of B cells were class-switched. T cell subsets (including T follicular helper cells and regulatory T cells) and other major immune compartments were largely unaffected by B cell depletion, and similar between relapsing and stable children. In conclusion, CyTOF analysis of immune cells from anti-CD20 antibody treated patients identifies class-switched B cells as the main subset whose expansion associates with disease relapse. Our findings set the basis for future studies exploring how identified subsets can be used to monitor treatment response and improve our understanding of the pathogenesis of the disease.

Current Understanding of Clinical Manifestations of COVID-19 in Glomerular Disease

Background

The novel coronavirus disease (COVID-19), also known as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is an evolving pandemic with significant mortality. Information about the impact of infection on glomerular disease patients in particular has been lacking. Understanding the virus's effect in glomerular disease is constantly changing. This review article summarizes the data published thus far on COVID-19 and its manifestations in pre-existing and de novo glomerular disease.

Summary

While patients with glomerular disease may be at higher risk of severe COVID-19 due to their immunosuppressed status, some data suggest that a low amount of immunosuppression may be helpful in mitigating the systemic inflammatory response which is associated with high mortality rates in COVID-19. There have been a few case reports on COVID-19 causing glomerular disease relapse in patients. Multiple mechanisms have been proposed for kidney injury, proteinuria, and hematuria in the setting of COVID-19. More commonly, these are caused by direct tubular injury due to hemodynamic instability and hypoxic injury. However, the cytokine storm induced by COVID-19 may trigger common post-viral glomerular disease such as IgA nephropathy, anti-GBM, and ANCA vasculitis that have also been described in COVID-19 patients. Collapsing glomerulopathy, a hallmark of HIV-associated nephropathy, is being reported SARS-CoV-2 cases, particularly in patients with high-risk APOL1 alleles. Direct viral invasion of glomerular structures is hypothesized to cause a podocytopathy due to virus's affinity to ACE2, but evidence for this remains under study.

Key Messages

Infection with SARS-CoV-2 may cause glomerular disease in certain patients. The mechanism of de novo glomerular disease in the setting of COVID-19 is under study. The management of patients with existing glomerular disease poses unique challenges, especially with regard to immunosuppression management. Further studies are needed to inform clinician decisions about the management of these patients during the COVID-19 pandemic.

Common risk variants in NPHS1 and TNFSF15 are associated with childhood steroid-sensitive nephrotic syndrome

To understand the genetics of steroid-sensitive nephrotic syndrome (SSNS), we conducted a genome-wide association study in 987 childhood SSNS patients and 3,206 healthy controls with Japanese ancestry. Beyond known associations in the HLA-DR/DQ region, common variants in NPHS1-KIRREL2 (rs56117924, P=4.94E-20, odds ratio (OR) =1.90) and TNFSF15 (rs6478109, P=2.54E-8, OR=0.72) regions achieved genome-wide significance and were replicated in Korean, South Asian and African populations. Trans-ethnic meta-analyses including Japanese, Korean, South Asian, African, European, Hispanic and Maghrebian populations confirmed the significant associations of variants in NPHS1-KIRREL2 (P_meta=6.71E-28, OR=1.88) and TNFSF15 (P_meta=5.40E-11, OR=1.33) loci. Analysis of the NPHS1 risk alleles with glomerular NPHS1 mRNA expression from the same person revealed allele specific expression with significantly lower expression of the transcript derived from the risk haplotype (Wilcox test p=9.3E-4). Because rare pathogenic variants in NPHS1 cause congenital nephrotic syndrome of the Finnish type (CNSF), the present study provides further evidence that variation along the allele frequency spectrum in the same gene can cause or contribute to both a rare monogenic disease (CNSF) and a more complex, polygenic disease (SSNS).

A longitudinal study on the effects of psychological stress on proteinuria in childhood steroid-sensitive nephrotic syndrome

OBJECTIVE

Steroid-sensitive nephrotic syndrome (SSNS) in children is often complicated by one or more relapses, as manifested by the appearance of proteinuria. Besides health-related triggers, psychological stress might be related to relapse. This longitudinal study examined the link between perceived stress, emotional valence (feeling happy vs. unhappy) and daily reported proteinuria, and investigated the temporal relation between stressful events and proteinuria.

METHOD

Sixteen children (4-13 years) diagnosed with SSNS were included. Patients kept an online diary for an average of 124 days, wherein they reported proteinuria (n = 1985 urine samples), perceived stress, emotional valence, medication use and health complaints. Stressful days were determined at the start of the study. Using multilevel analysis, the following associations were tested: (1) the relation between perceived stress, emotional valence and proteinuria, and (2) the temporal relation between stressful days and proteinuria.

RESULTS

Appearance of proteinuria was reported in 410/1985 urine samples. Perceived stress and not emotional valence significantly predicted proteinuria (95% CI [0.11, 0.27]), even five days later. There was a significant temporal association between stressful days and proteinuria (95% CI [0.22, 1.14]). The effect sizes of these associations were small, f = 0.04 and f = 0.12, respectively.

CONCLUSIONS

Our findings suggest that psychological stress may trigger proteinuria in children with SSNS. Future research in larger samples is needed to support our findings.

Predictors of frequent relapsing and steroid-dependent nephrotic syndrome in children

AIM

To determine the predictors of frequent relapses and steroid dependency in children with steroid-sensitive nephrotic syndrome.

MATERIAL AND METHODS

All children aged six months to 18 years with steroid-sensitive nephrotic syndrome registered in the nephrology clinic between 2003 and 2015 at a tertiary center who were followed up for at least 1year after onset were included in the study.

RESULTS

Two hundred seventy-seven patients with steroid-sensitive nephrotic syndrome who were followed up for at least 1 year from onset of disease were included. There were 157 infrequent relapsers and 120 frequent relapsers (frequent relapses and or steroid-dependent). Compared with infrequent relapsers, frequent relapsers had a significantly lower age at onset (51.53±40.42 vs. 61.97±40.66 months; p=0.035), lesser time for first relapse (time from the start of initial treatment to first relapse (8.65±11.99 vs. 23.46±24.05 months; p<0.001) and a higher number of relapses with infection (8.65±11.99 vs. 1.25±1.85; p<0.001). On multivariate logistic regression analysis, time for first relapse less than six months [OR: 3.93; 95% CI: (1.97-7.82)] and concomitant infection during relapses [OR: 1.82; 95% CI:(1.56-2.14)] were significant predictors of frequent relapses, and males were less likely to become frequent relapsers [OR: 0.48; 95% CI:(0.24-0.93)]. Kaplan-Meier analysis and the log-rank test also showed that a first relapse within six months was associated with frequent relapses. Age at onset and inadequate steroid therapy at onset did not determine frequent relapses.

CONCLUSION

Shorter time for first relapse and concomitant infection during relapses can predict future frequent relapses. These predictors may be useful to counsel patients, to follow them up more closely, and to develop better treatment protocols and relapse-specific interventions.

Does Zika virus infection induce prolonged remissions in children with idiopathic nephrotic syndrome?

BACKGROUND

Zika is an emerging mosquito-borne flavivirus. We report two pediatric patients diagnosed with idiopathic nephrotic syndrome who achieved complete remission of the disease after suffering Zika virus (ZIKV) infection.

CASE DIAGNOSIS/TREATMENT

The first patient was a young girl aged 2.5 years with steroid-dependent nephrotic syndrome who was subsequently diagnosed with ZIKV infection. Following the infection, the steroid dose could be reduced until complete withdrawal. The patient persists in complete remission. The second patient was a steroid-resistant boy aged 7 years who was scheduled for a renal biopsy when he was diagnosed with ZIKV infection. A week after the recovery phase of the acute rash, proteinuria was noted to be gradually falling. Today, 12 months later, he is in complete remission of the disease.

CONCLUSIONS

We are aware that the improvement observed in our two patients after ZIKV infection may be be random. However, it is also possible that future studies will discover that ZIKV infection has some effect on the cellular immune system similar to that of measles infection.

Steroid-sensitive nephrotic syndrome in children: triggers of relapse and evolving hypotheses on pathogenesis

Nephrotic syndrome remains the most common manifestation of glomerular disease in childhood. Minimal change nephropathy is the most common cause of the syndrome in children. Despite its initial high response rate to corticosteroids and its favorable prognosis, relapses are common leading to increased morbidity and cost of treatment.This review seeks to appraise the common triggers of relapse and to highlight the evolving hypotheses about the pathogenesis of the syndrome. Literature search was conducted through PubMed, Google web search and Cochrane Database of Systematic reviews using relevant search terms.Acute respiratory infections and urinary tract infections are the most frequent infectious triggers of relapse. Targeted interventions like initiating corticosteroid or its dose-adjustment during episodes of acute respiratory infection and zinc supplementation are reportedly effective in reducing relapse rates. Hypotheses on pathogenesis of the syndrome have evolved from the concepts of 'immune dysregulation', 'increased glomerular permeability' to 'podocytopathy'.Although development of drugs which can regulate the pathways for podocyte injury offers future hope for effective and targeted treatment, the relapse-specific interventions currently contribute to significant reduction in disease morbidity.

Protective effects of Huang Qi Huai granules on adriamycin nephrosis in rats

Huang Qi Huai (HQH) granules, a mixture of Chinese herbs, contains trametes robiniophila murr, wolfberry fruit, and Polygonatum. We investigated the mechanism of the protective effects of HQH on adriamycin nephrosis (ADR) in rats. Adriamycin nephrotic rats were induced by a single dose of 5 mg/kg adriamycin. For the HQH-treated adriamycin nephrosis group, 1 day after treatment with 5 mg/kg adriamycin, the rats were administered once-daily oral gavage of 2 mg/kg HQH for 15 days. All the rats were killed at day 15. Histological changes were observed by light microscopy and transmission electron microscope. Nephrin and podocin expression levels were measured by real-time RT-PCR and Western blot. Proteinuria was measured by the Bradford protein assay. Serum TNF-α and IL-1β levels were evaluated by ELISA. Macrophage infiltration was detected by immunohistochemistry and immunoblotting, respectively. ADR rats showed heavy proteinuria, podocyte and tubulointerstitial injury, macrophage infiltration, and increased levels of serum cytokines TNF-α and IL-1β. HQH significantly ameliorated the adriamycin-induced renal injury. These data were validated in the cultured podocytes. The podocytes were treated by adriamycin in the presence or absence of HQH and nephrin and podocin expression and TNF-α and IL-1β synthesis and secretion were determined by real-time RT-PCR, immunoblotting, and ELISA, respectively. Adriamycin significantly reduced nephrin and podocin expression, which was significantly restored by the treatment of HQH. HQH treatment inhibited adriamycin-induced TNF-α and IL-1β expression. Our findings suggest that HQH significantly reduces proteinuria, prevents podocyte injury, and ameliorates tubulointerstitial damage. Inhibition of inflammatory cytokine expression and macrophage infiltration may be the protective mechanism of HQH.

Epidemiology and risk factors for thromboembolic complications of childhood nephrotic syndrome: a Midwest Pediatric Nephrology Consortium (MWPNC) study

OBJECTIVES

To identify clinical variables predictive of the risk of thromboembolism (TE), and to confirm the incidence of TE in primary and secondary childhood nephrotic syndrome (NS).

STUDY DESIGN

A comprehensive chart review identified 326 children with NS from any cause evaluated between 1999 and 2006. These patients had a total of 1472.8 patient-years of follow-up. Comparison statistics, survival analysis, and logistic regression were used to define TE epidemiology and clinical risk factors.

RESULTS

We found that 9.2% of our cohort had experienced at least 1 TE. The overall incidence was 20.4 patients with TEs/1000 patient-years. The median time to the first TE was 70.5 days after diagnosis of NS. Deep venous thrombosis was the most common TE (76%) and was frequently associated with the use of a central venous catheter (45%). Significant independent predictors of TE included age > or = 12 years at onset of NS (P < .0001), severity of proteinuria (P < .0001), and history of TE preceding diagnosis of NS (P < .0001). Life- or limb-threatening TEs represented 23.7% of the events.

CONCLUSIONS

Children with NS should be carefully followed for TE, particularly those who are age 12 years or older, have severe proteinuria, or have a previous history of TE.