Epidemiology of idiopathic nephrotic syndrome in children: endemic or epidemic?

Resolution versus persistence of childhood idiopathic nephrotic syndrome-A population-based study

AIM

To determine the duration of relapsing childhood idiopathic nephrotic syndrome (INS).

METHODS

In this population-based study, we retrospectively analysed the computerised database of Israel's largest health maintenance organisation. Children (age 2-10 years) with a new INS diagnosis and a corticosteroid (CS) prescription between 2000 and 2010 were included. NS category was determined, according to CS and/or steroid-sparing agents (SSA) purchases.

RESULTS

Out of 1 669 977 eligible children, 608 fulfilled inclusion criteria. Patients in the fourth quartile of purchases (n = 132) had an older age at last relapse (17.9 ± 6.3 vs. 11.3 ± 5.9 years, p < 0.001) and more SSA use (78.8% vs. 20%, p < 0.001) compared to the remaining three quartiles. A single episode occurred in 84 patients. Of the remaining 524 patients (males 66%, diagnosis age: 4.8 ± 2.2 years, SSA prescribed: 35%) who were followed for 15.5 ± 5.1 years, 113 (21.6%) had a continuing disease at an age of 19.3 ± 6.3 years. The leftover 411 entered long-lasting treatment-free remission at age 11.2 ± 5.7 years.

CONCLUSION

In this multicentre study, we identified INS disease course by medication delivery. NS long-standing remission occurs at age 11.2 ± 5.7 years in most cases. However, the disease continues into adulthood in a fifth of the relapsing patients, implicating the need for proper transition to adult care.

Advances in Diagnosis and Treatment of Inherited Kidney Diseases in Children

Background

Inherited kidney diseases (IKDs) in children pose unique diagnostic and therapeutic challenges. IKD significantly impact patient quality of life, morbidity, mortality, and cost to the healthcare system. With over 150 genetic abnormalities, they account for approximately 30% of cases requiring renal replacement therapy. There is an urgent need to advance both diagnosis and treatment strategies. In this review, we present recent advances in diagnosis and treatment for facilitating personalized treatment approaches.

Summary

The diagnostic landscape for IKDs have evolved significantly, emphasizing precise genetic identification and classification of these disorders. Recent advancements include the refinement of genetic testing techniques, such as whole exome sequencing, which has improved the accuracy of diagnosing specific diseases and facilitated early intervention strategies. Additionally, this review categorizes IKDs based on genetic abnormalities and clinical manifestations, enhancing understanding and management approaches. Finally, it summarizes the corresponding treatment, and lists the application of emerging therapeutic options such as gene therapy and organoids, which show promise in transforming treatment outcomes.

Key Messages

This review summarizes the common types of IKDs in children, including their diagnosis and treatment advances, and provides an update on the status of gene therapy development for these disorders.

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.

Real-word adrenocorticotropic hormone treatment for childhood-onset nephrotic syndrome

Background

Current first-line anti-proteinuric treatments do not produce a satisfactory therapeutic effect in a considerable number of patients with nephrotic syndrome (NS). Interest in adrenocorticotropic hormone (ACTH) for the treatment of NS has recently been revived. The present study investigated the efficacy and safety of ACTH treatment in children with frequent relapsing NS (FRNS), steroid-dependent NS (SDNS), and steroid-resistant NS (SRNS).

Method

The ACTH treatment group was comprised of NS patients receiving ACTH treatment. Patients with serum cortisol concentrations <85.3 nmol/L and who had not received ACTH treatment previously were enrolled in the control group from January 2018 to January 2021. The maintenance dose of prednisone, the number of disease recurrences, the time of first disease relapse, immunosuppressant use, serum cortisol levels, and adverse events were recorded in both groups.

Results

Fifty-one patients were included in the ACTH group, and twenty-one patients were enrolled in the control group. Concurrent treatment with one or more immunosuppressive and/or cytotoxic treatments occurred in 92.2% and 85.7% of patients in the ACTH and control groups, respectively, throughout the study period. A greater reduction in the prednisone maintenance dose was observed in the ACTH group compared with the control group after 1 year of follow up (0.603 ± 0.445 mg/kg vs. 0.267 ± 0.500 mg/kg, p = 0.006). During the one-year study period, fewer participants experienced one or more disease relapses in the ACTH group (45.1%) compared to the control group (76.2%, odds ratio = 3.896, p = 0.016). The number of disease recurrences per patient in the ACTH group was less than that in the control group (median difference = -1, p = 0.006). The mean length of remission was 8.902 m and 7.905 m in the ACTH group and control group, respectively. A log-rank test showed a longer relapse free survival for patients in the ACTH group (p = 0.046), but the Breslow test showed no significant difference between groups (p = 0.104). Ten patients in the ACTH group successfully discontinued all drug therapies. No patients in the control group were able to discontinue drug therapy as of February 2022.

Conclusion

ACTH, combined with multiple drugs, is effective at reducing the prednisone maintenance dose and may effectively prevent disease relapses in childhood NS.

KIAA0101 and IL2RA Were Identified as Core Genes in Hormone-Resistant Nephropathy

Objectives

To analyze the tissue heterogeneity of hormone-sensitive and drug-resistant nephrotic syndrome genes using a bioinformatics approach and to analyze gene-related functional pathways.

Methods

The limma package of R software was used to screen differential genes from the nephropathy datasets GSE145969 and GSE189734. The differential genes were analyzed for functional and pathway enrichment in terms of biological processes, cellular components, and molecular functions. The Metascape tool was used to construct protein networks for the differential genes, and the results were imported into Cytoscape software for visualization. The genes were identified as key modules and genes using the MCODE plug-in. Gene set enrichment analysis was performed for the HALLMARK analysis of the two microarray key genes to obtain the relevant pathways.

Results

GSE145969 screened 351 differential genes, 168 upregulated genes, and 183 downregulated genes. The differential genes were enriched in biological processes, cellular components, and molecular functions, such as myocardial contraction, intracellular nonmembrane organelles, and structural molecular activities. The protein-protein interaction (PPI) network contained 140 nodes, with the highest-scoring module containing seven genes, and the MCODE plug-in calculated the downseed. The key gene was KIAA0101, whose HALLMARK pathway was significantly enriched in the mTORC1 signaling pathway. A total of 263 differential genes were screened by GSE189734, and they were enriched in biological processes, molecular functions, and cellular components, such as immune system processes, signaling receptor binding, and the cytoplasmic matrix. The PPI network contained 253 nodes, with the highest-scoring module containing 37 genes. The seed gene obtained through the MCODE plug-in calculation was IL2RA, whose HALLMARK pathway was significantly enriched in the KRAS signaling pathway.

Conclusion

By analyzing the gene sets of different tissues in nephropathy, two key genes, namely KIAA0101 and IL2RA, were obtained. Their gene function enrichment is related to cell growth, development, and reproduction. Therefore, IL2RA and KIAA0101 can be used as diagnostic markers for hormone-resistant nephropathy.

Haemostatic profile of children with nephrotic syndrome attending University of Nigeria Teaching Hospital Ituku-Ozalla, Nigeria

Background

Haemostatic derangements are thought to be due to an imbalance between hepatic synthesis of pro-coagulants and urinary losses of anticoagulants.

Objectives

This study evaluated the coagulation profile of Nigerian children with nephrotic syndrome and examined the relationship between coagulation variables, disease state and steroid responsiveness.

Methods

A cross- sectional hospital based study on evaluation of coagulation profile of children with nephrotic syndrome compared with their age- and gender- matched controls.

Results

The median fibrinogen level in subjects and controls was the same (2.9 g/L). Sixteen of 46 (35%) children with nephrotic syndrome had hyperfibrinogenaemia. The median fibrinogen level of children in remission was 2.3 g/L and differed significantly when compared with those of children in relapse (p = 0.001). The median APTT of children with nephrotic syndrome was 45.0 s and differed significantly compared with those of controls (42.0 s) (p value = 0.02). The median prothrombin time in children with and without nephrotic syndrome were 12.0 and 13.0 s respectively, (p = 0.004). About 90% of children with nephrotic syndrome had INR within reference range. Thrombocytosis was found in 15% of children with nephrotic syndrome. The median platelet count in children with new disease was 432 × 10³cells/mm³ and differed significantly when compared with those of controls (p = 0.01).

INR was significantly shorter in children with steroid resistant nephrotic syndrome (SRNS) (median 0.8 s; IQR 0.8 -0.9 s) compared with controls (median 1.0 s; IQR 1.0 -1.1 s) (p = 0.01). Steroid sensitivity was the strongest predictor of remission in children with nephrotic syndrome; steroid sensitive patients were 30 times more likely to be in remission than in relapse (OR 30.03; CI 2.01 – 448.04).

Conclusion

This study shows that the haemostatic derangements in childhood nephrotic involve mostly fibrinogen, APTT, PT, INR and platelet counts. Antithrombin levels are largely unaffected. Variations in fibrinogen, APTT, PT and INR values may be due to the heterogeneous nature of the disease.

Alteration in DNA-binding affinity of Wilms tumor 1 protein due to WT1 genetic variants associated with steroid - resistant nephrotic syndrome in children

Approximately one third of children with steroid-resistant nephrotic syndrome (SRNS) carry pathogenic variants in one of the many associated genes. The WT1 gene coding for the WT1 transcription factor is among the most frequently affected genes. Cases from the Czech national SRNS database were sequenced for exons 8 and 9 of the WT1 gene. Eight distinct exonic WT1 variants in nine children were found. Three children presented with isolated SRNS, while the other six manifested with additional features. To analyze the impact of WT1 genetic variants, wild type and mutant WT1 proteins were prepared and the DNA-binding affinity of these proteins to the target EGR1 sequence was measured by microscale thermophoresis. Three WT1 mutants showed significantly decreased DNA-binding affinity (p.Arg439Pro, p.His450Arg and p.Arg463Ter), another three mutants showed significantly increased binding affinity (p.Gln447Pro, p.Asp469Asn and p.His474Arg), and the two remaining mutants (p.Cys433Tyr and p.Arg467Trp) showed no change of DNA-binding affinity. The protein products of WT1 pathogenic variants had variable DNA-binding affinity, and no clear correlation with the clinical symptoms of the patients. Further research is needed to clarify the mechanisms of action of the distinct WT1 mutants; this could potentially lead to individualized treatment of a so far unfavourable disease.

The immunopathogenesis of idiopathic nephrotic syndrome: a narrative review of the literature

Idiopathic nephrotic syndrome (INS) is a common glomerular disease in childhood, and the immunological involvement in the pathogenesis of non-genetic INS, although not fully elucidated, is evident. This narrative review aims to offer a concise and in-depth view of the current knowledge on the immunological mechanisms of the development of INS as well as the role of the immunological components of the disease in the responsiveness to treatment. T cell immunity appears to play a major role in the INS immunopathogenesis and has been the first to be linked to the disease. Various T cell immunophenotypes are implicated in INS, including T-helper-1, T-helper-2, T-helper-17, and T regulatory cells, and various cytokines have been proposed as surrogate biomarkers of the disease; however, no distinct T helper or cytokine profile has been conclusively linked to the disease. More recently, the recognition of the role of B cell mediated immunity and the various B cell subsets that are dysregulated in patients with INS have led to new hypotheses on the underlying immunological causes of INS. Finally, the disambiguation of the exact mechanisms of the INS development in the future may be the key to the development of more targeted personalized approaches in managing INS.

CONCLUSIONS

INS demonstrates particularly interesting immunopathogenetic pathways, in which multiple interactions between T cell and B cell immunity and the podocyte are involved. The disambiguation of these pathways will provide promising novel therapeutic targets in INS.

WHAT IS KNOWN

• INS is the most common glomerular disease in the paediatric population, and its onset and relapses have been linked to various immunological triggers. • Multiple immunological mechanisms have been implicated in the pathogenesis of INS; however, no single distinct immunological profile has been recognized.

WHAT IS NEW

• Th17 cells and Treg cells play an important role in the immune dysregulation in INS. • Transitional B cell levels as well as the transitional/memory B cell ratio have been correlated to nephrotic relapses and have been proposed as biomarkers of INS relapses in SSNS patients.

Population-based identification and temporal trend of children with primary nephrotic syndrome: The Kaiser Permanente nephrotic syndrome study

INTRODUCTION

Limited population-based data exist about children with primary nephrotic syndrome (NS).

METHODS

We identified a cohort of children with primary NS receiving care in Kaiser Permanente Northern California, an integrated healthcare delivery system caring for >750,000 children. We identified all children <18 years between 1996 and 2012 who had nephrotic range proteinuria (urine ACR>3500 mg/g, urine PCR>3.5 mg/mg, 24-hour urine protein>3500 mg or urine dipstick>300 mg/dL) in laboratory databases or a diagnosis of NS in electronic health records. Nephrologists reviewed health records for clinical presentation and laboratory and biopsy results to confirm primary NS.

RESULTS

Among 365 cases of confirmed NS, 179 had confirmed primary NS attributed to presumed minimal change disease (MCD) (72%), focal segmental glomerulosclerosis (FSGS) (23%) or membranous nephropathy (MN) (5%). The overall incidence of primary NS was 1.47 (95% Confidence Interval:1.27-1.70) per 100,000 person-years. Biopsy data were available in 40% of cases. Median age for patients with primary NS was 6.9 (interquartile range:3.7 to 12.9) years, 43% were female and 26% were white, 13% black, 17% Asian/Pacific Islander, and 32% Hispanic.

CONCLUSION

This population-based identification of children with primary NS leveraging electronic health records can provide a unique approach and platform for describing the natural history of NS and identifying determinants of outcomes in children with primary NS.

Estimation of childhood nephrotic syndrome incidence: data from the atlanta metropolitan statistical area and meta-analysis of worldwide cases

BACKGROUND

Epidemiological data on childhood idiopathic nephrotic syndrome (INS) are limited. We estimated childhood INS incidence in a racially and ethnically diverse U.S. population and performed a meta-analysis of published reports to examine differences by race, ethnicity, and time.

METHODS

One hundred seventy-five children aged 1-17 years living in the Atlanta Metropolitan Statistical Area (MSA) between 2013 and 2018 were identified by retrospective chart review. Annual INS incidence was estimated by dividing cases by population data from the Georgia Department of Public Health. We calculated pooled incidence estimates using random-effects regression models in a meta-analysis of the current and prior studies. Subgroup incidence estimates by race, ethnicity, and time were compared and tested for heterogeneity.

RESULTS

One hundred seventy-five children aged 1-17 were diagnosed with INS between 2013 and 2018 in the Atlanta MSA. Average annual incidence was 2.13/100,000 (95% CI, 1.83-2.47). Twenty-four studies were included in meta-analysis. Our study was the only one to report incidence for Hispanic children, 2.13/100,000/y (95% CI, 1.40-3.10). In meta-analysis, incidence was highest in Asian children (7.14/ 100,000/y; 95% CI, 4.73-9.54), followed by Black (3.53/100,000/y; 95% CI, 2.93-4.12), and Caucasian (1.83/100,000/y; 95% CI, 1.52-2.14). Annual incidence in the U.S. was stable comparing studies performed before and after 1984, 2.05 vs. 2.26/100,000 (p 0.08).

CONCLUSIONS

Risk of INS may be higher among Asian and Black children compared to White children. Incidence appears stable over time in the U.S. Future studies should use standardized methodology and assess the contribution of demographic and genetic factors to INS incidence and long-term outcomes.

Incidence and Relapse of Idiopathic Nephrotic Syndrome: Meta-analysis

CONTEXT

Idiopathic nephrotic syndrome (INS) in children is a disease with considerable morbidity, yet the incidence and risk for relapse have not been systematically reviewed.

OBJECTIVE

To estimate the overall pooled weighted incidence and risk for relapse of INS in children.

DATA SOURCES

Medline and Embase (until December 2020).

STUDY SELECTION

All studies reporting incidence (per 100 000 children per year) and/or risk for relapse (the proportion of patients who experience ≥1 relapse) of INS in children (age: <18 years) were eligible.

DATA EXTRACTION

After quality assessment, data were extracted: study (design, localization, and sample size) and patient (age, sex, steroid response, and ethnicity) characteristics, incidence, and risk for relapse.

RESULTS

After screening, 73 studies were included for analysis (27 incidence, 54 relapse). The overall pooled weighted estimate and corresponding prediction interval (PI) of the incidence was 2.92 (95% PI: 0.00-6.51) per 100 000 children per year. Higher incidences were found in non-Western countries (P < .001). Incidence tended to be lower in white children, but this was not significant. The overall pooled weighted estimate of the risk for relapse was 71.9% (95% PI: 38.8-95.5). Between 1945 and 2011, incidence did not change (P = .39), yet the risk for relapse decreased significantly (P = .024), from 87.4% to 66.2%.

LIMITATIONS

There was no full-text availability (n = 33), considerable heterogeneity, and limited studies from Africa, Latin America, and Asia.

CONCLUSIONS

INS has a low incidence with ethnic variation but high risk for relapse. Although corticosteroids have significantly reduced the risk for relapse, it remains unacceptably high, underscoring the need for alternative treatment strategies.

Current understandings in treating children with steroid-resistant nephrotic syndrome

Steroid-resistant nephrotic syndrome (SRNS) remains a challenge for paediatric nephrologists. SRNS is viewed as a heterogeneous disease entity including immune-based and monogenic aetiologies. Because SRNS is rare, treatment strategies are individualized and vary among centres of expertise. Calcineurin inhibitors (CNI) have been effectively used to induce remission in patients with immune-based SRNS; however, there is still no consensus on treating children who become either CNI-dependent or CNI-resistant. Rituximab is a steroid-sparing agent for patients with steroid-sensitive nephrotic syndrome, but its efficacy in SRNS is controversial. Recently, several novel monoclonal antibodies are emerging as treatment option, but their efficacy remains to be seen. Non-immune therapies, such as angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers, have been proven efficacious in children with SRNS and are recommended as adjuvant agents. This review summarizes and discusses our current understandings in treating children with idiopathic SRNS.

IPNA clinical practice recommendations for the diagnosis and management of children with steroid-resistant nephrotic syndrome

Idiopathic nephrotic syndrome newly affects 1-3 per 100,000 children per year. Approximately 85% of cases show complete remission of proteinuria following glucocorticoid treatment. Patients who do not achieve complete remission within 4-6 weeks of glucocorticoid treatment have steroid-resistant nephrotic syndrome (SRNS). In 10-30% of steroid-resistant patients, mutations in podocyte-associated genes can be detected, whereas an undefined circulating factor of immune origin is assumed in the remaining ones. Diagnosis and management of SRNS is a great challenge due to its heterogeneous etiology, frequent lack of remission by further immunosuppressive treatment, and severe complications including the development of end-stage kidney disease and recurrence after renal transplantation. A team of experts including pediatric nephrologists and renal geneticists from the International Pediatric Nephrology Association (IPNA), a renal pathologist, and an adult nephrologist have now developed comprehensive clinical practice recommendations on the diagnosis and management of SRNS in children. The team performed a systematic literature review on 9 clinically relevant PICO (Patient or Population covered, Intervention, Comparator, Outcome) questions, formulated recommendations and formally graded them at a consensus meeting, with input from patient representatives and a dietician acting as external advisors and a voting panel of pediatric nephrologists. Research recommendations are also given.

Nephrotic syndrome-associated hypercoagulopathy is alleviated by both pioglitazone and glucocorticoid which target two different nuclear receptors

BACKGROUND

Thrombosis is a potentially life-threatening nephrotic syndrome (NS) complication. We have previously demonstrated that hypercoagulopathy is proportional to NS severity in rat models and that pioglitazone (Pio) reduces proteinuria both independently and in combination with methylprednisolone (MP), a glucocorticoid (GC). However, the effect of these treatments on NS-associated hypercoagulopathy remains unknown. We thus sought to determine the ability of Pio and GC to alleviate NS-associated hypercoagulopathy.

METHODS

Puromycin aminonucleoside-induced rat NS was treated with sham, Low- or High-dose MP, Pio, or combination (Pio + Low-MP) and plasma was collected at day 11. Plasma samples were collected from children with steroid-sensitive NS (SSNS) and steroid-resistant NS (SRNS) upon presentation and after 7 weeks of GC therapy. Plasma endogenous thrombin potential (ETP), antithrombin (AT) activity, and albumin (Alb) were measured using thrombin generation, amidolytic, and colorimetric assays, respectively.

RESULTS

In a rat model of NS, both High-MP and Pio improved proteinuria and corrected hypoalbuminemia, ETP and AT activity (p < .05). Proteinuria (p = .005) and hypoalbuminemia (p < .001) were correlated with ETP. In childhood NS, while ETP was not different at presentation, GC therapy improved proteinuria, hypoalbuminemia, and ETP in children with SSNS (p < .001) but not SRNS (p = .330).

CONCLUSIONS

Both Pio and GC diminish proteinuria and significantly alleviate hypercoagulopathy. Both Pio and MP improved hypercoagulopathy in rats, and successful GC therapy (SSNS) also improved hypercoagulopathy in childhood NS. These data suggest that even a partial reduction in proteinuria may reduce NS-associated thrombotic risk.

Five-year outcome of children with idiopathic nephrotic syndrome: the NEPHROVIR population-based cohort study

BACKGROUND

The optimal therapeutic regimen for children at onset of idiopathic nephrotic syndrome (INS) is still under debate. A better knowledge of the disease's course is necessary to design more appropriate and/or personalized treatment protocols.

METHODS

We report the 5-year outcome of patients included from December 2007 to May 2010 in the prospective multicentric and multiethnic population-based NEPHROVIR study. Patients were treated at onset according to the French steroid protocol (3990 mg/m², 18 weeks). Data were collected at 5 years or last follow-up.

RESULTS

Out of the 188 children with nephrotic syndrome (121 boys, 67 girls; median age 4.1 years), 174 (93%) were steroid-sensitive. Six percent of steroid-sensitive patients required intravenous steroid pulses to get into remission. Relapse-free rate for steroid-sensitive patients was 21% (36/174) at last follow-up (median 72 months). A first relapse occurred in138 steroid sensitive patients (79%) with a median time of 8.3 months (IQ 3.4-11.3). Out of the 138 relapsers, 43 were frequent relapsers. Age at onset below 4 years was the only predictive factor of relapse, while gender, ethnicity, and delay to first remission were not. At 96 months of follow-up, 83% of frequent relapsers were still under steroids and/or immunosuppressive drugs.

CONCLUSIONS

The treatment of the first flare deserves major improvements in order to reduce the prevalence of relapsers and the subsequent long-lasting exposure to steroids and immunosuppression.

Influenza vaccination among children with idiopathic nephrotic syndrome: an investigation of practices

Background

Annual influenza vaccination is recommended for all children with idiopathic nephrotic syndrome (INS) in France. Consequently, the Social Security automatically sends prescriptions to all patients suffering from a chronic disease. The aim of this study was to evaluate the follow-up to these recommendations.

Methods

We conducted a monocentric retrospective investigation of practices. We included all children with steroid-sensitive INS in remission who attended our clinics from January 1st 2015 to January 1st 2017, resided in France and had a valid phone number. Data were collected from May 2017 to June 2017 through a phone interview and review of clinical charts.

Results

75 patients met the inclusion criteria. The parents of 57 children could be reached by phone and agreed to participate to the survey. 35/57 (61.4%) declared having received a prescription during the 2016–2017 campaign. Only 14 children (24.6%) were vaccinated. 17/43 (39.5%) parents of unvaccinated children had concerns about the safety of the vaccine, 16/43 (37.2%) were not aware of the recommendations, 5/43 (11.6%) had been recommended by their physician not to vaccinate their child, 3/43 (7%) forgot to have them vaccinated and 2/43 (4.6%) reported no reason. 13/43 (30%) unvaccinated children presented a relapse during the flu season - 2/13 during an influenza-like illness - whereas 1/14 (7%) immunized children presented a relapse during the six months of post-vaccination follow-up. Relapse rates were not increased in vaccinated children compared to unvaccinated children (p = 0.15), nor in the 6 months following vaccination compared to the 6 months prior (1/14 vs 5/14, p = 0.20).

Conclusions

1) < 2/3 patients were properly prescribed the recommended yearly influenza vaccination at our center 2) only 1/4 were vaccinated and most of their parents were misinformed. Physicians must be aware of this and should make every effort to better inform their patients on the risks of flu illness and the benefits and safety of the vaccination.

Electronic supplementary material

The online version of this article (10.1186/s12882-019-1240-2) contains supplementary material, which is available to authorized users.

Clinical course & management of childhood nephrotic syndrome in Germany: a large epidemiological ESPED study

Background

Nephrotic syndrome (NS) is one of the most frequent occurring chronic kidney diseases in childhood, despite its rarely occurrence in the general population. Detailed information about clinical data of NS (e.g. average length of stay, complications) as well as of secondary nephrotic syndrome (SNS) is not well known.

Methods

A nationwide ESPED follow-up study presenting the clinical course and management of children with NS in Germany.

Results

In course of 2 years, 347 children developed the first onset of NS, hereof 326 patients (93.9%) had a primary NS, and 19 patients had a SNS (missing data in 2 cases), the majority due to a Henoch-Schönlein Purpura. Patients with steroid-resistant NS (SRNS) stayed significantly longer in hospital than children with steroid-sensitive NS (25.2 vs. 13.3 d, p <  0.001). Patients with bacterial/viral infections stayed longer in hospital (24.9 d/19.5d) than children without an infection (14.2 d/14.9 d; p <  0.001; p = 0.016). Additionally, children with urinary tract infections (UTI) (p < 0,001), arterial hypertension (AH) (p < 0.001) and acute renal failure (ARF) (p < 0,001) stayed significantly longer in hospital.

Patients with SRNS had frequent complications (p = 0.004), such as bacterial infections (p = 0.013), AH (p < 0.001), UTI (p < 0.001) and ARF (p = 0.007). Children with a focal segmental glomerulosclerosis (FSGS) had significantly more complications (p = 0.04); specifically bacterial infections (p = 0.01), UTI (p = 0.003) and AH (p < 0,001). Steroid-resistance was more common in patients with UTI (p < 0.001) and in patients with ARF (p = 0.007). Furthermore, steroid-resistance (p < 0.001) and FSGS (p < 0.001) were more common in patients with AH.

Conclusions

This nationwide, largest German study presents results on the clinical course of children with NS considering a diverse range of complications that can occur with NS. The establishment of a region-wide and international pediatric NS register would be useful to conduct further diagnostic and therapy studies with the aim to reduce the complication rate and to improve the prognosis of NS, and to compare the data with international cohorts.

Electronic supplementary material

The online version of this article (10.1186/s12882-019-1233-1) contains supplementary material, which is available to authorized users.

Effect of different rituximab regimens on B cell depletion and time to relapse in children with steroid-dependent nephrotic syndrome

BACKGROUND

Several studies have demonstrated that rituximab (RTX) improves relapse-free survival in patients with steroid-dependent nephrotic syndrome (SDNS). However, these studies used various RTX regimens and there are few data comparing these regimens in children with SDNS. In this retrospective study, we assessed the effect of three different initial RTX regimens on both time to B cell reconstitution and to first relapse.

METHODS

Sixty-one SDNS patients receiving a first course of RTX were included. Group 1 received one injection of 100 mg/m², group 2 received one injection of 375 mg/m², and group 3 received two injections of 375 mg/m² at day 0 and day 7. Time to B cell reconstitution and time to first relapse and respective risk factors were studied.

RESULTS

Median time to B cell reconstitution was 2.5 [1.8-3.5], 5.0 [3.9-6.0], and 6.6 [4.6-7.8] months in groups 1, 2, and 3, respectively. RTX regimen was associated with time to B cell reconstitution (HRs group 2 vs. 3, 4.07 [1.96-8.48]; group 1 vs. 3, 11.13 [4.04-30.67]). One-year relapse-free survival was 50% [58-77], 59% [42-76], and 72% [46-87] in groups 1, 2, and 3, respectively. RTX regimen was associated with risk of relapse (HRs group 2 vs. 3, 1.55 [0.51-4.65]; group 1 vs. 3, 4.98 [1.15-21.60]).

CONCLUSIONS

The initial dose of rituximab impacts time to B cell reconstitution and the probability of relapse. Risk of relapse is also associated with patient characteristics, suggesting that RTX regimen could be modified for each patient to balance efficacy, cost, and side effects.

[Up to date of pathophysiology mechanism of idiopathic nephrotic syndromes: Minimal change disease and focal and segmental glomerulosclerosis]

Idiopathic nephrotic syndrome represents up to 30% of adult glomerulopathies. However, its prognosis according to remission, relapse and renal failure remains unchanged since the 80s and prediction remains difficult. Physiopathology of adult idiopathic nephrotic syndrome is complex and multifactorial, including immunologic and environmental factors and a putative permeability-circulating factor, still unknown. In this point of view, we propose to summarize actual knowledge about idiopathic minimal change disease and focal and segmental glomerulosclerosis physiopathology.

Transethnic, Genome-Wide Analysis Reveals Immune-Related Risk Alleles and Phenotypic Correlates in Pediatric Steroid-Sensitive Nephrotic Syndrome

Background Steroid-sensitive nephrotic syndrome (SSNS) is a childhood disease with unclear pathophysiology and genetic architecture. We investigated the genomic basis of SSNS in children recruited in Europe and the biopsy-based North American NEPTUNE cohort.Methods We performed three ancestry-matched, genome-wide association studies (GWAS) in 273 children with NS (Children Cohort Nephrosis and Virus [NEPHROVIR] cohort: 132 European, 56 African, and 85 Maghrebian) followed by independent replication in 112 European children, transethnic meta-analysis, and conditional analysis. GWAS alleles were used to perform glomerular cis-expression quantitative trait loci studies in 39 children in the NEPTUNE cohort and epidemiologic studies in GWAS and NEPTUNE (97 children) cohorts.Results Transethnic meta-analysis identified one SSNS-associated single-nucleotide polymorphism (SNP) rs1063348 in the 3' untranslated region of HLA-DQB1 (P=9.3×10-23). Conditional analysis identified two additional independent risk alleles upstream of HLA-DRB1 (rs28366266, P=3.7×10-11) and in the 3' untranslated region of BTNL2 (rs9348883, P=9.4×10-7) within introns of HCG23 and LOC101929163 These three risk alleles were independent of the risk haplotype DRB1*07:01-DQA1*02:01-DQB1*02:02 identified in European patients. Increased burden of risk alleles across independent loci was associated with higher odds of SSNS. Increased burden of risk alleles across independent loci was associated with higher odds of SSNS, with younger age of onset across all cohorts, and with increased odds of complete remission across histologies in NEPTUNE children. rs1063348 associated with decreased glomerular expression of HLA-DRB1, HLA-DRB5, and HLA-DQB1.Conclusions Transethnic GWAS empowered discovery of three independent risk SNPs for pediatric SSNS. Characterization of these SNPs provide an entry for understanding immune dysregulation in NS and introducing a genomically defined classification.

Clinical and genetic heterogeneity in familial steroid-sensitive nephrotic syndrome

BACKGROUND

Familial steroid-sensitive nephrotic syndrome (SSNS) is a rare condition. The disease pathophysiology remains elusive. However, bi-allelic mutations in the EMP2 gene were identified, and specific variations in HLA-DQA1 were linked to a high risk of developing the disease.

METHODS

Clinical data were analyzed in 59 SSNS families. EMP2 gene was sequenced in families with a potential autosomal recessive (AR) inheritance. Exome sequencing was performed in a subset of 13 families with potential AR inheritance. Two variations in HLA-DQA1 were genotyped in the whole cohort.

RESULTS

Transmission was compatible with an AR (n = 33) or autosomal dominant (AD, n = 26) inheritance, assuming that familial SSNS is a monogenic trait. Clinical features did not differ between AR and AD groups. All patients, including primary (n = 7) and secondary steroid resistant nephrotic syndrone (SRNS), (n = 13) were sensitive to additional immunosuppressive therapy. Both HLA-DQA1 variations were found to be highly linked to the disease (OR = 4.34 and OR = 4.89; p < 0.001). Exome sequencing did not reveal any pathogenic mutation, neither did EMP2 sequencing.

CONCLUSIONS

Taken together, these results highlight the clinical and genetic heterogeneity in familial SSNS. Clinical findings sustain an immune origin in all patients, whatever the initial steroid-sensitivity. The absence of a variant shared by two families and the HLA-DQA1 variation enrichments suggest a complex mode of inheritance.

[Idiopathic nephrotic syndrome]

Nephrotic syndrome (NS) is defined by massive proteinuria and hypoalbuminemia, with resulting hyperlipidemia and edema. The most common cause of NS in children is idiopathic nephrotic syndrome (INS), also called nephrosis. Its annual incidence has been estimated to 1-4 per 100,000 children and varies with age, race, and geography. Many agents or conditions have been reported to be associated with INS such as infectious diseases, drugs, allergy, vaccinations, and malignancies. The disease may occur during the 1st year of life, but it usually starts between the ages of 2 and 7 years. INS is characterized by a sudden onset, edema being the major presenting symptom, but may rarely be discovered during a routine urine analysis. The disease may also be revealed by a complication such as hypovolemia, infection (pneumonia and peritonitis due to Streptococcus pneumoniae), deep-vein or arterial thromboses, and pulmonary embolism. Renal biopsy is usually not indicated in a child aged 1-10 years with typical symptoms and a complete remission with corticosteroids. Conversely, it is indicated in children under 1 year in case of macroscopic hematuria, hypertension, low C3 levels, persistent renal failure, or steroid resistance. Steroid therapy is applied in all children whatever the histopathology. Initial prednisone therapy in France consists of 60mg/m² administered daily for 4 weeks (maximum dose, 60mg/day), followed by alternate-day prednisone with tapering doses. Eight-five to 90 % patients are steroid-responsive and may relapse, but the majority still responds to steroids over the subsequent courses. Only 1-3 % of patients who are initially steroid-sensitive subsequently become steroid-resistant. Children with primary or secondary steroid-resistance are at risk of end-stage kidney disease. Symptomatic treatment includes salt restriction, fluid restriction when natremia is less than 125 meq/L, reduction of saturated fat and carbohydrates, calcium and vitamin D supplements, anticoagulation, and vaccination. Albumin infusions are only indicated in case of complications. Diuretics should be restricted to cases of severe edema, after hypovolemia has been corrected.

FCGR2A single nucleotide polymorphism confers susceptibility to childhood-onset idiopathic nephrotic syndrome

Childhood-onset idiopathic nephrotic syndrome affects 1.15-3.4 children/100,000 children/year in Western Countries. Immune-mediated mechanisms, particularly T cell-mediated, are thought to play a key pathogenic role. The genetic basis of the disease is still poorly understood. We tested the association between single nucleotide polymorphisms (SNPs) of four genes encoding Fc gamma receptors (FCGR2A, FCGR2B, FCGR3A, FCGR3B) and idiopathic nephrotic syndrome in a case-control study of paediatric patients. Children with idiopathic nephrotic syndrome (aged 1-16 years) were included. FCGR2A rs1801274 and FCGR3A rs396991 SNPs were genotyped using real-time PCR with the TaqMan method, while FCGR2B rs1050501 and FCGR3B NA1/NA2 were genotyped using Sanger sequencing. Fisher's exact test was used to explore genetic association. We enrolled 103 idiopathic nephrotic syndrome patients and 181 healthy controls. A significant association was found between idiopathic nephrotic syndrome and FCGR2A rs1801274 SNP (both with the T allele and the TT genotype, p value=0.0009, OR 1.81, 95% CI 1.27-2.59 and p value=0.0007, OR 2.39, 95% CI 1.44-3.99, respectively). No associations were found for the remaining SNPs. Fc gamma receptors might modulate response to rituximab; since 60 of the enrolled patients were treated with rituximab, we also tested the association between the studied SNPs and rituximab efficacy in this patient subgroup, but found only a weak association with FCGR2A CC genotype (p value=0.03). The FCGR2A rs1801274 SNP in the gene encoding the activating receptor CD32A confers susceptibility to idiopathic nephrotic syndrome.

[Childhood steroid-dependent idiopathic nephrotic syndrome: Predictive factors for the need of immunosuppressive treatment]

BACKGROUND AND AIMS

More than half of the children with idiopathic nephrotic syndrome become steroid-dependent (or frequent relapsers) and will later require the use of complementary treatment aiming to reduce steroids' side effects and to limit the number of proteinuria relapses. It appears important to identify these children as early as possible in order to adapt their treatment. The aim of this study was to analyze the population of children, under 18 years of age, diagnosed between 1/01/2000 and 31/05/2015 with an idiopathic nephrotic syndrome and followed at the Montpellier University Hospital to search for criteria predictive of steroid-sparing agent use.

METHODS

In this retrospective study of children with idiopathic nephrotic syndrome, the exclusion criteria were primary steroid resistance and children with no proteinuria relapse after diagnosis.

RESULTS

Eighty-four children (54 boys) were included in this study. The mean follow-up duration was 5.5 years (0.75-16). The mean age at diagnosis was 4.6 years. Sixty-five children (77%) received at least one steroid-sparing agent during their follow-up, within a mean 10 months after diagnosis. In these patients, the first relapse of the disease occurred earlier when compared with the children who were maintained on steroid alone (4 months vs 7 months; P<0.001). The use of methylprednisolone pulses to obtain a remission, the cumulative dose of steroid treatment, and the number of proteinuria relapses were also significantly correlated with the use of complementary immunosuppressive therapy.

CONCLUSION

We found no predictive criteria of the use of steroid-sparing agents at diagnosis in our population of children. Nevertheless, with the steroid regimen used, the time within which the first proteinuria relapse occurred appears to be a significant criterion for the secondary use of a steroid-sparing agent. These data should be taken into account when choosing the treatment regimen.