Atopy, serum IgE, and interleukin-13 in steroid-responsive nephrotic syndrome

Early, Noninvasive Clinical Indicators of Kidney Prognosis in Primary Nephrotic Syndrome: A Retrospective Exploratory Study

This retrospective exploratory study aimed to identify early clinical indicators of kidney prognosis in primary nephrotic syndrome (NS). Univariate Cox proportional hazards regression analysis identified clinical parameters in the 2-month period after initiating immunosuppressive therapy (IST); it predicted 40% reduction in the estimated glomerular filtration rate (eGFR) in 36 patients with primary NS. Time-dependent receiver operating characteristic curve analysis was used to evaluate the performance of the predictors for the cumulative incidence of 40% reduction in the eGFR up to 8 years after initiating IST. The mean follow-up period was 71.9 months. The eGFR was reduced by 40% in four patients. Significant predictors for time to 40% reduction in the eGFR were as follows: an increase in the serum soluble urokinase plasminogen activator receptor (s-suPAR) 2 months after initiating IST (Δs-suPAR (2M); hazard ratio (HR) for every 500 pg/mL increase: 1.36, P=0.006), s-suPAR at 2 months after initiating IST (s-suPAR (2M); HR for every 500 pg/mL increase: 1.13, P=0.015), urinary protein-to-creatinine ratio (u-PCR) (u-PCR (2M); HR for every 1.0 g/gCr increase: 2.94, P=0.003), and urinary liver-type fatty acid-binding protein (u-L-FABP) (u-L-FABP (2M); HR for every 1.0 μg/gCr increase: 1.14, P=0.006). All four factors exhibited high predictive accuracy for cumulative incidence of 40% reduction in the eGFR up to 8 years after initiating IST, with areas under the receiver operating characteristic curve of 0.92 for Δs-suPAR (2M), 0.87 for s-suPAR (2M), 0.93 for u-PCR (2M), and 0.93 for u-L-FABP (2M). These findings suggest that Δs-suPAR (2M), s-suPAR (2M), u-PCR (2M), and u-L-FABP (2M) could be useful indicators of initial therapeutic response for predicting kidney prognosis in primary NS.

Case Report: The Application of Dupilumab in Atopic Dermatitis Children Complicated With Nephrotic Syndrome

Nephrotic syndrome (NS) tends to be more common in patients with history of allergies. Atopic dermatitis (AD) is one of the most common allergic diseases in children. Dupilumab, a dual IL-4 and IL-13 inhibitor, has been widely used to treat AD patients. However, the efficacy and safety of Dupilumab in NS is unclear. We reported two AD patients with NS comorbidities treated with Dupilumab. The outcomes showed the good control of NS and less systemic steroids and/or immunosuppressive agents use during the Dupilumab treatment period, accompanied by significant relief of AD symptoms. We suggest prospective pilot studies and randomized controlled trials could be carried out to validate the efficacy and safety of Dupilumab in the treatment of NS patients.

Serum IgE Levels Are Associated With the Prognosis of Minimal Change Disease

Background

Previous reports showed that some patients with minimal change disease (MCD) had high serum immunoglobulin E (IgE) levels. This study aimed to explore the proportion of MCD patients with high serum IgE levels and evaluate the correlation between serum IgE levels and MCD remission and relapse.

Methods

This study enrolled 222 new-onset patients with renal biopsy-confirmed MCD from October 2012 to October 2019 at the First Affiliated Hospital of Zhejiang University in Hangzhou, China. Patients’ demographics and clinical parameters were analyzed.

Results

The results indicated that 70.3% of 222 MCD patients had high serum IgE levels (IgE > 100.0 IU/mL). Moreover, 134 patients were treated with glucocorticoids alone and divided into the low- and high-IgE groups, according to the median serum IgE level (523.5 IU/mL). The mean time to complete remission of the low- and high-IgE groups was 29.0 ± 2.2 and 45.7 ± 4.2 days, respectively (log-rank test; P = 0.002). The mean time to total remission was 19.1 ± 1.4 and 31.6 ± 3.2 days of the low- and high-IgE groups, respectively (log-rank test; P < 0.001). The mean time to first relapse in the low- and high-IgE groups was 701.2 ± 65.0 and 425.0 ± 52.6 days, respectively (log-rank test; P = 0.002). Serum IgE ≥ 523.5 IU/mL was an independent correlation factor affecting the patients’ remission and relapse.

Conclusion

Serum IgE level was an independent correlation factor for MCD remission and relapse. MCD patients with high serum IgE levels were prone to delayed remissions and early relapses.

The role of the immune system in idiopathic nephrotic syndrome

Idiopathic nephrotic syndrome (INS) in children is characterized by massive proteinuria and hypoalbuminemia and usually responds well to steroids. However, relapses are frequent, which can require multi-drug therapy with deleterious long-term side effects. In the last decades, different hypotheses on molecular mechanisms underlying INS have been proposed and several lines of evidences strongly indicate a crucial role of the immune system in the pathogenesis of non-genetic INS. INS is traditionally considered a T-cell-mediated disorder triggered by a circulating factor, which causes the impairment of the glomerular filtration barrier and subsequent proteinuria. Additionally, the imbalance between Th17/Tregs as well as Th2/Th1 has been implicated in the pathomechanism of INS. Interestingly, B-cells have gained attention, since rituximab, an anti-CD20 antibody demonstrated a good therapeutic response in the treatment of INS. Finally, recent findings indicate that even podocytes can act as antigen-presenting cells under inflammatory stimuli and play a direct role in activating cellular pathways that cause proteinuria. Even though our knowledge on the underlying mechanisms of INS is still incomplete, it became clear that instead of a traditionally implicated cell subset or one particular molecule as a causative factor for INS, a multi-step control system including soluble factors, immune cells, and podocytes is necessary to prevent the occurrence of INS. This present review aims to provide an overview of the current knowledge on this topic, since advances in our understanding of the immunopathogenesis of INS may help drive new tailored therapeutic approaches forward.

Low regulatory T-cells: A distinct immunological subgroup in minimal change nephrotic syndrome with early relapse following rituximab therapy

Rituximab is an important second line therapy in difficult nephrotic syndrome (NS), especially given toxicity of long-term glucocorticoid or calcineurin inhibitor (CNI) use. However, clinical response to rituximab is heterogenous. We hypothesized that this was underpinned by immunological differences amongst patients with NS. We recruited a cohort of 18 subjects with glucocorticoid-dependent or glucocorticoid-resistant childhood-onset minimal change NS who received rituximab either due to CNI nephrotoxicity, or due to persistent glucocorticoid toxicity with inadequate response to cyclophosphamide or CNIs. Immunological subsets, T-cell activation assays and plasma cytokines were measured at baseline and 6-months post-rituximab. Time to relapse was bifurcated: 56% relapsed within one year ("early relapse"), while the other 44% entered remission mainly lasting ≥3 years ("sustained remission"). At baseline, early relapse compared to sustained remission group had lower regulatory T-cells (Tregs) [2.94 (2.25, 3.33)% vs 6.48 (5.08, 7.24)%, P<0.001], PMA-stimulated IL-2 [0.03 (0, 1.85)% vs 4.78 (0.90, 9.18)%, P=0.014] and IFNγ [2.22 (0.18, 6.89)% vs 9.47 (2.72, 17.0)%, P=0.035] levels. Lower baseline Treg strongly predicted early relapse (ROC-AUC 0.99, 95% CI 0.97-1.00, P<0.001). There were no differences in baseline plasma cytokine levels. Following rituximab, there was significant downregulation of Th2 cytokines in sustained remission group (P=0.038). In particular, IL-13 showed a significant decrease in sustained remission group [-0.56 (-0.64, -0.35)pg/ml, P=0.007)], but not in the early relapse group. In conclusion, early relapse following rituximab is associated with baseline reductions in Treg and T-cell hyporesponsiveness, which suggest chronic T-cell activation and may be useful predictive biomarkers. Sustained remission, on the other hand, is associated with downregulation of Th2 cytokines following rituximab.

Serum immunoglobulin E level in children with nephrotic syndrome

Background and objective: The most supported theory for Nephrotic Syndrome (NS) etiology is that it is immune-mediated. This study aims to assess the level of serum IgE in children with Steroid Sensitive NS (SSNS) at relapse and remission, and its correlation with the presence of atopy. Methods: This cross-sectional study was approved by the Department of Pediatrics, College of Medicine, Al-Nahrain University (Baghdad, Iraq) and conducted at Al-Imamain Al-Kadhimain Medical City (Baghdad, Iraq), and Child Central Teaching Hospital (Baghdad, Iraq), and included 31 children SSNS. The data collected was: age, sex, residency, onset of NS, response to steroid, frequency of relapses, and the history of atopy of the patient and his relatives. Serum IgE level was measured during relapse for all patients and for 9 patients while in remission. Results: Atopy was present in 18 (58.06%) of patients. The median serum IgE level was 295.5 IU/mL (range 54-2864 IU/mL) in relapse, which is significantly higher (P-value =0.006) than in remission 228.5 IU/mL (range 62-2069 IU/mL). Median serum level of IgE in patients with atopy was 290.5 IU/mL (range 24-2864 IU/mL) which was higher than that of patients without atopy (median 231 IU/mL, range 23-1314 IU/m) (P-value = 0.029). Patients required longer period to respond to steroid therapy (>10 days) had a significantly higher median of IgE (341 IU/mL) than those who required <10 days to respond (161 IU/mL) (P-value =0.045). Conclusions: Increased IgE level is documented during relapse and in atopic children with SSNS. Longer duration to respond to steroid therapy is associated significantly with higher serum IgE during relapse.

The Effect of Interleukin-4 and Dexamethasone on RNA-Seq-Based Transcriptomic Profiling of Human Podocytes: A Potential Role in Minimal Change Nephrotic Syndrome

Interleukin-4 (IL-4) expression is implicated in the pathogenesis of nephrotic syndrome (NS). This study aimed to investigate the changes in the transcriptomes of human podocytes induced by IL-4 treatment and to analyze whether these changes could be affected by simultaneous steroid treatment. Three groups of human podocytes were treated with control, IL-4, and IL-4 plus dexamethasone (DEX), respectively. We performed whole-transcriptome sequencing to identify differentially expressed genes (DEGs) between the groups. We investigated relevant biological pathways using Gene Ontology (GO) enrichment analyses. We also attempted to compare and validate the DEGs with the genes listed in PodNet, a literature-based database on mouse podocyte genes. A total of 176 genes were differentially expressed among the three groups. GO analyses showed that pathways related to cytoskeleton organization and cell signaling were significantly enriched. Among them, 24 genes were listed in PodNet, and 12 of them were previously reported to be associated with IL-4-induced changes in human podocytes. Of the 12 genes, the expression levels of BMP4, RARB, and PLCE1 were reversed when podocytes were simultaneously treated with DEX. In conclusion, this study explored changes in the transcriptome profiles of human podocytes treated with IL-4. Few genes were reported in previous studies and were previously validated in experiments with human podocytes. We speculate that IL-4 may exert pathogenic effects on the transcriptome of human podocytes, and a few genes may be involved in the pathogenesis.

Spontaneous remission of minimal change nephrotic syndrome in an elderly man

Minimal change nephrotic syndrome (MCNS) cases achieving spontaneous remission without external factors are rarely reported. We report a case of MCNS that achieved spontaneous remission without external factors that triggered its onset. An 82-year-old male patient was admitted to the hospital for close examination of nephrotic syndrome. Renal biopsy was performed and MCNS was diagnosed. Owing to the patient's age and history of foot and microvascular arteriovenous thrombosis, we did not start immunosuppressive drugs, including steroids, and opted for conservative management. After conservative treatment, proteinuria gradually decreased, and the patient achieved complete remission. Given that the patient had a history of urinary protein and thrombosis, recurrence of MCNS was considered again this time. In addition, the involvement of external factors that trigger the onset of MCNS was not found. In conclusion, in elderly-onset MCNS, clinicians generally hesitate to initiate treatment with an immunosuppressive drug, containing steroids, because of its many complications. Thus, our data provide valuable insight into MCNS.

Rituximab in adult minimal change disease and focal segmental glomerulosclerosis - What is known and what is still unknown?

Primary forms of minimal change disease and focal segmental glomerulosclerosis are rare podocytopathies and clinically characterized by nephrotic syndrome. Glucocorticoids are the cornerstone of the initial immunosuppressive treatment in these two entities. Especially among adults with minimal change disease or focal segmental glomerulosclerosis, relapses, steroid dependence or resistance are common and necessitate re-initiation of steroids and other immunosuppressants. Effective steroid-sparing therapies and introduction of less toxic immunosuppressive agents are urgently needed to reduce undesirable side effects, in particular for patients whose disease course is complex. Rituximab, a B cell depleting monoclonal antibody, is increasingly used off-label in these circumstances, despite a low level of evidence for adult patients. Hence, critical questions concerning drug-safety, long-term efficacy and the optimal regimen for rituximab-treatment remain unanswered. Evidence in the form of large, multicenter studies and randomized controlled trials are urgently needed to overcome these limitations.

Establishment of a novel nomogram for the clinically diagnostic prediction of minimal change disease, -a common cause of nephrotic syndrome

Background

Minimal change disease (MCD) is one of the major causes of nephrotic syndrome (NS). A confirmed MCD diagnosis mainly depends on renal biopsy at present, which is an invasive procedure with many potential risks. The overall incidence of complications caused by renal biopsy procedures has been reported as approximately 11 and 6.6% outside and within China, respectively. Unfortunately, there is currently no noninvasive procedure or practical classification method for distinguishing MCD from other primary glomerular diseases available.

Method

A total of 1009 adult patients who underwent renal biopsy between January 2017 and November 2019 were enrolled in this study. Twenty-five parameters extracted from patient demographics, clinical manifestations, and laboratory test results were statistically analysed. LASSO regression analysis was further performed on these parameters. The parameters with the highest area under the curve (AUC) were selected and used to establish a logistic diagnostic prediction model.

Results

Of the 25 parameters, 14 parameters were significantly different (P < 0.05). MCD patients were mostly younger (36 (22, 55) vs. 41 (28.75, 53)) and male (59% vs. 52%) and had lower levels of diastolic blood pressure (DBP) (79 (71, 85.5) vs. 80 (74, 89)) and IgG (5.42 (3.17, 6.36) vs. 9.38 (6.79, 12.02)) and higher levels of IgM (1.44 (0.96, 1.88) vs. 1.03 (0.71, 1.45)) and IgE (160 (46.7, 982) vs. 47.3 (19, 126)) than those in the non-MCD group. Using the LASSO model, we established a classifier for adults based on four parameters: DBP and the serum levels of IgG, IgM, IgE. We were able to clinically classify adult patients with NS into MCD and non-MCD using this model. The validation accuracy of the logistic regression model was 0.88. A nomogram based on these four classifiers was developed for clinical use that could predict the probability of MCD in adult patients with NS.

Conclusions

A LASSO model can be used to distinguish MCD from other primary glomerular diseases in adult patients with NS. Combining the model and the nomogram potentially provides a novel and valuable approach for nephrologists to diagnose MCD, avoiding the complications caused by renal biopsy.

IL-13-driven alterations in hepatic cholesterol handling contributes to hypercholesterolemia in a rat model of minimal change disease

Circulating factors have been implicated in the pathogenesis of minimal change disease (MCD), and may have direct effects on cholesterol metabolism. This study investigated the pathogenesis of hypercholesterolemia in an IL-13 overexpression rat model of MCD prior to the onset of proteinuria, so as to establish the direct contribution of IL-13, especially with regard to hepatic cholesterol handling. In this model of MCD, the temporal relationship between hypercholesterolemia and proteinuria was first identified. Plasma proprotein convertase subtilisin/kexin type 9 (Pcsk9) and liver ATP-binding cassette sub-family G member 5 (Abcg5) were measured using ELISA. Liver Ldlr and liver X receptor alpha (Lxra) were quantified with Western blot. Abcg5-mediated cholesterol efflux in IL-13-stimulated rat primary hepatocytes was measured using taurocholate as cholesterol acceptor. The role of Lxra was validated using a luciferase assay in Lxre-luciferase-transfected IL-13-stimulated hepatocytes. IL-13-transfected rats developed hypercholesterolemia prior to proteinuria, with 35% of rats hypercholesterolemic but only 11% proteinuric by Day 20 (P = 0.04). These pre-proteinuric hypercholesterolemic rats showed elevations in total and LDL-cholesterol, but not hypertriglyceridemia or hepatic steatosis. The hypercholesterolemia was associated with increased hepatic Pcsk9 synthesis and enhanced circulating Pcsk9 levels, which correlated strongly with plasma total cholesterol (r = 0.73, P&lt;0.001). The hypercholesterolemia was also contributed by decreased Abcg5 expression and activity, due to reduced Lxra expression. Lxra expression correlated with plasma total cholesterol levels (r = −0.52, P = 0.01), and overexpression of pLxra in rat hepatocytes abrogated the IL-13-mediated down-regulation of Lxre-driven gene expression. In conclusion, we have shown that IL-13 induced changes in hepatic cholesterol handling in a cytokine-induced rat model of MCD, resulting in hypercholesterolemia which can precede the onset of proteinuria.

Interleukin-4 and Interleukin-13 Gene Polymorphisms in Children With Idiopathic Nephrotic Syndrome

Background: Idiopathic Nephrotic syndrome (INS) is an immune-mediated disease in which a number of cytokines, including IL-4 and IL-13, have been implicated in the pathogenesis. Cytokine gene polymorphisms might affect their levels and activity. Therefore, may affect INS susceptibility and response to treatment. The aim of the study was to determine the association of IL-4 and IL-13 gene polymorphisms and INS susceptibility and their effects on steroid responsiveness in children. Methods: The polymorphisms in IL-4 and IL-13 genes were detected by PCR-RFLP in 155 INS patients and 64 controls. Results: A total of 132 steroid-sensitive (SS) and 23 steroid resistance (SR) INS patients; mean age 7.3 ± 4.0 years, were included. Male: Female ratio was 2:1. No significant statistical differences were detected in the frequency of CC, CT, and TT genotypes of IL-4 gene compared to controls (P = 0.57, 0.61, and 1.00, respectively). There was no significant difference in the T and C-allele frequencies, in SS and SR subgroups. Analysis of IL-13 gene polymorphism also did not show significant statistical differences in the frequency of QQ, RQ, and RR genotypes compared to controls (P = 0.74, 1.00, and 0.68, respectively). No significant difference was found in the Q and R-allele frequency. However, the heterozygous RQ genotype of the IL13 gene was significantly higher in SS INS patients compared to the SR INS cases (P = 0.04). Conclusion: Our findings did not show an association between IL-4 and IL-13 gene polymorphisms and INS susceptibility. However, IL-13 RQ genotype was expressed more in children with INS who are steroid sensitive.

Prevalence of Asthma and Allergies and Risk of Relapse in Childhood Nephrotic Syndrome: Insight into Nephrotic Syndrome Cohort

OBJECTIVE

To determine the lifetime prevalence of allergies in childhood nephrotic syndrome, the seasonality of presentation and relapses, and the impact of allergies on subsequent relapses.

STUDY DESIGN

In a longitudinal cohort of children with nephrotic syndrome (ages 1-18 years), assessment for allergic diseases was conducted using the validated and modified version of the International Study of Asthma and Allergies in Childhood questionnaire at enrollment. Outcomes included frequently relapsing nephrotic syndrome, relapse rates, and the relapse-free duration after initial steroid therapy.

RESULTS

Among 277 participants, the majority were male (65%) with a median age of 3.7 years (IQR 2.8-5.8) at presentation. A total of 64% reported lifetime allergies with 20% having asthma, 33% wheezing, 27% eczema, and 24% rhinitis. Over 3.3 years of follow-up, presence of asthma and allergies was not associated with frequently relapsing nephrotic syndrome (OR 1.20; 95% CI 0.60, 2.40), higher relapse rates (relative risk 0.95; 95% CI 0.71, 1.27), or risk of first relapse (hazard ratio 1.10; 95% CI 0.83, 1.47) compared with those with no history of allergic diseases. There was also no seasonal variation evident at initial presentation or frequency of relapses.

CONCLUSIONS

Two-thirds of children with nephrotic syndrome at presentation have allergic symptoms and asthma; however, neither are associated with an increased frequency of relapses.

Immunoglobulin E and G Levels in Predicting Minimal Change Disease before Renal Biopsy

Purpose

The diagnosis of minimal change disease in adults relies mainly on renal biopsy, but this procedure is not without complications. Despite the advancements in technique of percutaneous renal biopsy, biopsy-related complications still occur. Bleeding is one of the major complications, which may lead to hemodynamic instability and, sometimes, even death. Thus, we developed a model to predict MCD for high-risk patients unsuitable for renal biopsy.

Methods

We enrolled 142 patients with nephrotic syndrome who received renal biopsy between October 2007 and April 2011 at one tertiary medical center in this study. Demographic, clinical, and prebiopsy laboratory variables were retrospectively recorded and analyzed.

Results

The overall prevalence of MCD was 26.8%. Age, hemoglobin levels, 24-hour urine protein, immunoglobulin (Ig) G, and IgE differed significantly between the MCD and non-MCD groups. Logistic regression analysis showed a significant increase in the risk of developing MCD as the number of Ig risk factors, namely, IgG < 450 mg/dl and IgE > 110 mg/dl, increased. Having both risk factors significantly increased the chances of receiving a diagnosis of MCD (by 31.84-fold, P =.007) compared with having neither. Combining the aforementioned clinical model and the 2 Ig risk factors was the best in predicting the diagnosis of MCD, with the area under a receiver-operating characteristic curve of 0.91.

Conclusions

Combining clinical model and this 2 Ig risk factors provides physicians simple and valuable clinical markers to diagnose MCD.

Synaptopodin is upregulated by IL-13 in eosinophilic esophagitis and regulates esophageal epithelial cell motility and barrier integrity

Eosinophilic esophagitis (EoE) is an allergic inflammatory disease of the esophagus mediated by an IL-13-driven epithelial cell transcriptional program. Herein, we show that the cytoskeletal protein synaptopodin (SYNPO), previously associated with podocytes, is constitutively expressed in esophageal epithelium and induced during allergic inflammation. In addition, we show that the SYNPO gene is transcriptionally and epigenetically regulated by IL-13 in esophageal epithelial cells. SYNPO was expressed in the basal layer of homeostatic esophageal epithelium, colocalized with actin filaments, and expanded into the suprabasal epithelium in EoE patients, where expression was elevated 25-fold compared with control individuals. The expression level of SYNPO in esophageal biopsies correlated with esophageal eosinophil density and was improved following anti-IL-13 treatment in EoE patients. In esophageal epithelial cells, SYNPO gene silencing reduced epithelial motility in a wound healing model, whereas SYNPO overexpression impaired epithelial barrier integrity and reduced esophageal differentiation. Taken together, we demonstrate that SYNPO is induced by IL-13 in vitro and in vivo, is a nonredundant regulator of epithelial cell barrier function and motility, and is likely involved in EoE pathogenesis.

Role of gut microbiota in idiopathic nephrotic syndrome in children

Nephrotic syndrome characterized by heavy proteinuria and edema is the most common chronic kidney disease in children. It is classified into three categories, of which the idiopathic type accounts for the vast majority of cases. As indicated by the name, the etiology of idiopathic nephrotic syndrome remains unknown though it has been suggested that impaired T cell function is involved. Recently, evidence has mounted to suggest that dysfunction in regulatory T cells plays an important role in the development of allergic disease, a recognized comorbid condition for children with idiopathic nephrotic syndrome. It is known that regulatory T cells are mainly induced by short chain fatty acids produced by gut microbiota and that children with allergy are reported to have aberrant gut microbiota. On this basis, we hypothesize that an aberrant microbiota, i.e., dysbiosis in the gut resulting in defective induction of regulatory T cells, is also involved in the etiology of idiopathic nephrotic syndrome in children. Our hypothesis can be directly tested by metagenome analysis using bacterial DNA extracted from the feces of patients with idiopathic nephrotic syndrome. Indirect evidence could be obtained by epidemiological survey, such as a comparative study of the environmental factors influencing the initial colonization of gut microbiota between patients with idiopathic nephrotic syndrome and age-matched healthy children. Factors that may disrupt this colonization include a cesarean delivery, formula feeding, excessive use of antibiotics, or the introduction of inappropriate solid foods containing a high amount of saturated fat. Based on this hypothesis, we suggest it would be clinically worthwhile to study whether administration of probiotics composed of commensal bacteria known to efficiently induce regulatory T cells in vitro could control the exacerbation or relapse of INS.

Montelukast improves the changes of cytoskeletal and adaptor proteins of human podocytes by interleukin-13

OBJECTIVE AND DESIGN

Interleukin-13 (IL-13) has recently been reported to be a potential cytokine in the pathogenesis of minimal-change nephrotic syndrome (MCNS). However, the mechanistic insights associated with podocyte dysfunction mediated by IL-13-induced changes in various slit diaphragm (SD) and cytoskeletal molecules have not yet been shown in cultured human podocytes in vitro.

MATERIALS

Human conditionally immortalized podocytes were used.

TREATMENT

Podocytes were incubated with various concentrations of IL-13 during the indicated time periods (6, 12, and 24 h) and montelukast was administered with the dose of 0.1 μg.

RESULTS

Treatment of IL-13 resulted in a progressive decrease in distinct processes or projections of the human podocytes and high dose of IL-13 increased podocyte permeability in vitro at 6 h. IL-13 had a substantial impact on the redistribution and rearrangement of zonula occludens (ZO)-1, synaptopodin, α-actinin, CD2-associated protein (CD2AP) in podocytes and disrupted the cytoskeletal connections in a concentration-dependent manner on confocal microscopy. IL-13 also down-modulated ZO-1, synaptopodin, α-actinin, CD2AP, and p130Cas at protein levels and upregulated β-catenin and B7-1 in podocytes. Furthermore, we demonstrated that down-modulated changes in various SD and cytoskeletal structures of human podocytes induced by IL-13 was significantly restored after treatment with montelukast with upregulation of B7-1.

CONCLUSION

Our results suggest that targeting IL-13 may be one of the important cytokines in the pathogenesis of MCNS and targeting IL-13 could be one of the potential therapeutic strategies in MCNS.

Novel role of Vav1-Rac1 pathway in actin cytoskeleton regulation in interleukin-13-induced minimal change-like nephropathy

Our established interleukin-13 (IL-13) overexpression rat model of minimal change-like nephropathy provided a platform to study the molecular signalling pathways in T-helper 2 (Th2) cytokine associated minimal change nephrotic syndrome (MCNS). We hypothesized that IL-13 may act directly on podocytes, causing podocyte foot process effacement and hence proteinuria in our rat model of minimal change-like nephropathy. The present study aimed firstly to delineate the glomerular 'gene signature' associated with IL-13-mediated dysregulation of podocyte-related proteins, and subsequently to investigate the role of the differentially regulated genes (DEGs) in IL-13-mediated podocyte injury. Glomerular transcriptional profile of IL-13-overexpressed rats showed characteristic features of podocyte injury with 87% of podocyte-related genes being significantly down-regulated. Gene expression of Vav1 was shown to be highly up-regulated in the glomeruli of IL-13-overexpressed rats and pathway analysis of the DEGs suggested a possible novel role of Vav1 in podocyte cytoskeleton remodelling. Immunofluorescence examination demonstrated glomerular expression of Vav1 in rats which co-localized with synaptopodin, confirming podocyte expression. However, positive staining for the phosphorylated form of Vav1 (p-Vav1) was only seen in IL-13-overexpressed rats. Moreover, in vitro IL-13 stimulation of human podocytes resulted in phosphorylation of Vav1. This was associated with Rac1 activation and actin cytoskeleton rearrangement, which was abrogated in Vav1 knockdown podocytes. In conclusion, we have demonstrated the role of Vav1-Rac1 pathway characterized by phosphorylation of Vav1, activation of Rac1 and the subsequent actin cytoskeleton rearrangement in IL-13-induced podocyte injury, possibly explaining the podocyte foot process effacement seen in our IL-13 overexpression rat model.

Elevation of plasma-soluble HLA-G in childhood nephrotic syndrome is associated with IgE

Background Nephrotic syndrome is related to immune system dysfunction. Soluble human leukocyte antigen-G has been suggested to have an immunomodulatory role. Additionally, human leukocyte antigen-G expression may be influenced by the 14-base pair insertion/deletion polymorphism. However, this molecule has not been investigated in nephrotic syndrome. Methods Fifty-five children with nephrotic syndrome were enrolled: 24 primary nephrotic syndrome patients and 31 recurrent nephrotic syndrome patients. A group of 120 healthy subjects were included as reference controls. Additionally, 22 patients in nephrotic syndrome remission after treatments were also included. Both nephrotic syndrome patients and healthy subjects were genotyped for the 14-base pair insertion/deletion polymorphism. Plasma soluble human leukocyte antigen-G concentrations and serum immunoglobulin concentrations were determined. Results Nephrotic syndrome patients showed significantly higher levels of both soluble human leukocyte antigen-G and immunoglobulin E compared to normal controls. Nephrotic syndrome patients presented a higher frequency of the -14-base pair allele than did normal controls. Soluble human leukocyte antigen-G concentrations in remission patients were dramatically lower compared to in nephrotic syndrome patients. Moreover, soluble human leukocyte antigen-G and immunoglobulin E were moderately correlated in nephrotic syndrome patients. Conclusions The present study demonstrated that plasma soluble human leukocyte antigen-G concentrations were significantly elevated and that a relationship between serum total immunoglobulin E in nephrotic syndrome patients and the human leukocyte antigen-G -14-base pair allele may be a risk factor for nephrotic syndrome. These findings suggest that soluble human leukocyte antigen-G may be used as a monitoring marker for nephrotic syndrome patients' condition.

Risk of Nephrotic Syndrome following Enteroviral Infection in Children: A Nationwide Retrospective Cohort Study

PURPOSE

Nephrotic syndrome is a common chronic illness encountered during childhood. Infections have been identified as a cause of nephrotic syndrome. The aim of this study was to evaluate the association between enteroviral infection and nephrotic syndrome.

METHODS

A nationwide retrospective cohort study was conducted by analyzing data from the National Health Insurance Research Database in Taiwan. Children aged <18 years with enteroviral infection were enrolled. Non-enterovirus-infected children were randomly selected as the comparison cohort. The primary endpoint was the occurrence of nephrotic syndrome.

METHODS

This study included 280,087 enterovirus-infected children and 280,085 non-enterovirus-infected children. The mean age of the enterovirus-infected children was 2.38 years, and 53.7% of these children were boys. The overall incidence densities of nephrotic syndrome for enterovirus- and non-enterovirus-infected children were 2.65 and 2.21 per 10,000 person-years, respectively. The enterovirus-infected cohort had a higher cumulative incidence of nephrotic syndrome than did the non-enterovirus-infected cohort (log-rank test, p = 0.01). Multivariable analyses revealed that children with enteroviral infection were significantly associated with an increased risk of nephrotic syndrome compared with those without enteroviral infection (adjusted hazard ratio, 1.20; 95% confidence interval, 1.04-1.39; p = 0.01), particularly in children infected with coxsackievirus. Subgroup analyses revealed that enterovirus-infected girls, children of blue-collar workers, and children without allergies had a higher risk of nephrotic syndrome than did children in the non-enterovirus-infected cohort.

CONCLUSION

This study revealed a significant association between enteroviral infection and nephrotic syndrome. Additional studies elucidating the role and pathogenesis of enterovirus in nephrotic syndrome are warranted.

Pathogenesis of minimal change nephrotic syndrome: an immunological concept

Idiopathic nephrotic syndrome (INS) in children is characterized by massive proteinuria and hypoalbuminemia. Minimal change nephrotic syndrome (MCNS) is the most common form of INS in children. The pathogenesis of MCNS still remains unclear, however, several hypotheses have been recently proposed. For several decades, MCNS has been considered a T-cell disorder, which causes the impairment of the glomerular filtration barrier with the release of different circulating factors. Increased levels of several cytokines are also suggested. Recently, a "two-hit" theory was proposed that included the induction of CD80 (B7-1) and regulatory T-cell (Treg) dysfunction, with or without impaired autoregulatory functions of the podocyte. In contrast to the well-established involvement of T cells, the role of B cells has not been clearly identified. However, B-cell biology has recently gained more attention, because rituximab (a monoclonal antibody directed against CD20-bearing cells) demonstrated a very good therapeutic response in the treatment of childhood and adult MCNS. Here, we discuss recent insights into the pathogenesis of MCNS in children.

Occurrence of common allergic diseases in children with idiopathic nephrotic syndrome

Background

Clinical and immunological studies have consistently shown a possible link between atopy and idiopathic nephrotic syndrome (INS). However, whether allergic diseases occur after INS develops is unknown.

Methods

From Taiwan’s National Health Insurance database, 1340 children with newly diagnosed INS and 5360 non-INS matched controls were identified in 2000–2007. By the end of 2008, the incidences and hazard ratios of four allergic diseases (allergic conjunctivitis, allergic rhinitis, atopic dermatitis, and asthma) were calculated.

Results

The incidence rates of all four allergic diseases were greater in the INS cohort than in the non-INS cohort in all age groups and decreased sharply as age increased in both cohorts. Children with INS had the highest adjusted hazard ratio (4.13; 95% confidence interval [CI], 2.50–6.83) for atopic dermatitis and the lowest adjusted hazard ratio (1.71; 95% CI, 1.39–2.09) for allergic rhinitis. Most of the allergic diseases appeared within 2–6 months after INS developed, and the incidences declined with increasing follow-up duration.

Conclusions

Allergic disorders are common in children with INS, especially within the first year after diagnosis. The role of INS in the development of allergic disorders should be elucidated to establish innovative disease intervention programs.

Effects of interleukin-13 and montelukast on the expression of zonula occludens-1 in human podocytes

PURPOSE

The aim of this study was to investigate whether pathologic changes in zonula occludens-1 (ZO-1) are induced by interleukin-13 (IL-13) in the experimental minimal-change nephrotic syndrome (MCNS) model and to determine whether montelukast, a leukotriene receptor antagonist, has an effect on ZO-1 restoration in cultured human podocytes.

MATERIALS AND METHODS

Human podocytes cultured on bovine serum albumin-coated plates were treated with different doses of IL-13 and montelukast and then examined for distribution using confocal microscopy and for ZO-1 protein levels using Western blotting.

RESULTS

ZO-1 was internalized and shown to accumulate in the cytoplasm of human podocytes in an IL-13 dose-dependent manner. High doses (50 and 100 ng/mL) of IL-13 decreased the levels of ZO-1 protein at 12 and 24 h (both p<0.01; n=3), which were significantly reversed by a high dose (0.5 μM) montelukast treatment (p<0.01; n=3).

CONCLUSION

Our results suggest that IL-13 alters the expression of ZO-1, and such alterations in the content and distribution of ZO-1 may be relevant in the pathogenesis of proteinuria in the MCNS model.

Evaluation of children with steroid-sensitive nephrotic syndrome in terms of allergies

BACKGROUND

The etiology of minimal-change disease is not fully known, it is believed to be mediated by the immune system. Minimal-change disease also reported as having association with atopy. In this study, atopy history, the levels of serum IgE, and skin prick test in children with steroid-sensitive nephrotic syndrome were investigated.

METHODS

A group of 30 children (mean age 7.7 ± 2.2 years, 56.6% male) diagnosed with steroid-sensitive nephrotic syndrome were included in the study. Serum immunoglobulin E levels and eosinophil counts were evaluated in children with steroid-sensitive nephrotic syndrome both in relapse and remission. Skin prick test was performed in remission.

RESULTS

Of the 30 children investigated, 11 (36.7%) had a history of atopy. The median serum total IgE levels in nephrotic children in relapse, with (445 IU/mL) and without atopy (310 IU/mL) were significantly higher than those in remission (respectively, 200 IU/mL, p = 0.021, and 42 IU/mL, p = 0.001). The skin prick tests for all the allergens were evaluated as negative in all the patients.

CONCLUSION

It was thought that increased IgE may reflect the activation of immune mechanism following various stimuli rather than a direct association with atopy in children with steroid-sensitive nephrotic syndrome.

Serum immunoglobulin E and interleukin-13 levels in children with idiopathic nephrotic syndrome

Serum IgE and IL-13 levels were estimated in 40 idiopathic nephrotic syndrome and 16 controls. There were 15 first episode nephrotic syndrome (FENS), 15 infrequent relapsing nephrotic syndrome (IRNS) and 10 patients belonged to frequent relapsing nephrotic syndrome (FRNS). Serum IgE and IL-13 levels were significantly increased in active nephrotic syndrome and its sub-groups as compared to controls and remission (p < 0.001). IgE levels did not differ significantly among different subgroups, while Il-13 was significantly higher in FRNS in comparison with FENS (p = 0.041). Both IgE and IL-13 levels were comparable in nephrotic patients with and without bronchial asthma. Serum IL-13 had significant positive correlation with IgE (r = 0.605, p < 0.001). Thus, raised levels of IgE and IL-13 are found in nephrotic syndrome and could have a role in the pathogenesis of disease.

Increased risk of idiopathic nephrotic syndrome in children with atopic dermatitis

BACKGROUND

Clinical and immunological studies have consistently shown a relationship between atopic diathesis and idiopathic nephrotic syndrome (INS). However, no large population cohort study has yet to demonstrate the nature of the relationship between these disorders.

METHODS

Claims data from a random selection of children representing half of the insured population in Taiwan were examined. During the period from 1998 to 2007, we identified 192,295 children aged <18 years with newly diagnosed atopic dermatitis (AD) and 769,169 frequency-matched controls. Incidence of INS and hazard ratios (HRs) were calculated.

RESULTS

The AD cohort had a 2-fold higher overall incidence of INS than the non-AD cohort [7.20 vs. 3.60 per 100,000 person-years, respectively; 95 % confidence interval (CI) 1.50-2.66]. The HR for INS increased with age and was higher among females. The HR for INS was also higher in AD children with more medical visits per year, ranging from 0.94 for those having ≤3 visits to 38.6 for those having >6 visits (trend test P < 0.0001). In particular, the risk of INS clearly increased during the initial 5 years after AD onset.

CONCLUSIONS

Children with AD have a greater incidence and risk of developing INS and this risk increases with AD severity.

Atopic dermatitis as a systemic disease

Atopic dermatitis (AD) is a chronic inflammatory disease that seriously affects the quality of life of these patients. Both immune deviations and epidermal barrier deficiency have been defined as pathophysiologic mechanisms in the disease development. The atopic march, or the natural progression form atopic dermatitis in infancy to asthma and allergic rhinitis, is a classic example for the multiorgan involvement in atopy. It has been hypothesized that epidermal barrier impairment is the primary pathologic condition responsible for the atopic march. In recent decades, a growing body of evidence has accumulated that AD can be accompanied by a variety of systemic diseases, such as autoimmune disorders, ophthalmologic involvement, eosinophilic gastroenteritis, inflammatory bowel disease, nephritic syndrome, and metabolic diseases. This contribution reviews these associations and focuses on the possible common underlying mechanisms of AD and the associated syndromes. We present a concept on AD as a multiorgan systemic disease.

Serum from minimal change patients in relapse increases CD80 expression in cultured podocytes

BACKGROUND

Minimal change disease (MCD) is the most common cause of nephrotic syndrome in children and is associated with the expression of CD80 in podocytes and the increased excretion of CD80 in urine. We hypothesized that serum from patients with MCD might stimulate CD80 expression in cultured podocytes.

METHODS

Sera and peripheral blood mononuclear cells (PBMCs) were collected from subjects with MCD in relapse and remission and from normal controls. Immortalized human podocytes were incubated with culture media containing patient sera or supernatants from patient and control PBMC cultures. CD80 expression was measured by quantitative PCR and western blot analysis.

RESULTS

Sera collected from patients with MCD in relapse, but not in remission, significantly increased CD80 expression (mean ± standard deviation: 1.8 ± 0.7 vs. 0.8 ± 0.2; p < 0.004) and CD80 protein secretion by podocytes (p < 0.05 between relapse and normal controls). No such CD80 increase was observed when podocytes were incubated with supernatants of PBMC cultures from patients in relapse.

CONCLUSIONS

Sera from MCD patients in relapse, but not in remission, stimulated CD80 expression in cultured podocytes. Identifying this factor in sera could provide insights into the pathogenesis of this disorder. No role in CD80 expression by podocytes was found for cytokines released by PBMCs.

The rationale and design of Insight into Nephrotic Syndrome: Investigating Genes, Health and Therapeutics (INSIGHT): a prospective cohort study of childhood nephrotic syndrome

BACKGROUND

Nephrotic syndrome is one of the most commonly diagnosed kidney diseases in childhood and its progressive forms can lead to chronic kidney disease (CKD) and/or end-stage renal disease (ESRD). There have been few longitudinal studies among a multi-ethnic cohort to determine potential risk factors influencing disease susceptibility, treatment response, and progression of nephrotic syndrome. Temporal relationships cannot be studied through cross-sectional study design. Understanding the interaction between various factors is critical to developing new strategies for treating children with kidney disease. We present the rationale and the study design of a longitudinal cohort study of children with nephrotic syndrome, the Insight into Nephrotic Syndrome: Investigating Genes, Health and Therapeutics (INSIGHT) study. The specific aims are to determine: 1) socio-demographic, environmental, and genetic factors that influence disease susceptibility; 2) rates of steroid treatment resistance and steroid treatment dependence, and identify factors that may modify treatment response; 3) clinical and genetic factors that influence disease susceptibility and progression to CKD and ESRD; and 4) the interaction between the course of illness and socio-demographic, environmental, and clinical risk factors.

METHODS/DESIGN

INSIGHT is a disease-based observational longitudinal cohort study of children with nephrotic syndrome. At baseline, participants complete questionnaires and provide biological specimen samples (blood, urine, and toenail clippings). Follow-up questionnaires and repeat biological specimen collections are performed annually for up to five years.

DISCUSSION

The proposed cohort will provide the structure to test various risk factors predicting or influencing disease susceptibility, treatment response, and progression to CKD among children with nephrotic syndrome.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier NCT01605266.

The clinical characteristics of steroid responsive nephrotic syndrome of children according to the serum immunoglobulin E levels and cytokines

PURPOSE

The nephrotic syndrome (NS) is characterized by the favorable response to glucocorticoid therapy and the development of NS may be associated with dysfunctional immune systems. In order to investigate the serum immunoglobulin E (IgE) levels and cytokines activity in pediatric NS, the total of 32 steroid responsive NS patients and 5 healthy controls were enrolled in this study.

MATERIALS AND METHODS

All patients were divided into two groups according to the initial serum IgE levels, such as normal and high IgE group, and their clinical characteristics were evaluated. In addition, serum levels of interleukin (IL)-4, IL-5, IL-10 and transforming growth factor (TGF)-β were compared and correlated with serum albumin, proteinuria by means of disease severity, and cytokines.

RESULTS

In the high IgE group, the higher comorbidity of allergic diseases and relapsing rate, the longer duration of steroid therapy before initial remission, and the higher serum IL-4 and IL-5 levels were found. In all patients, initially higher serum levels of IL-4 and IL-5 declined to normal levels after steroid therapy, whereas the serum IL-10 levels showed no significant difference between nephrotic phase (heavy proteinuria) and remission phase (no proteinuria) of NS. The serum TGF-β levels of the nephrotic phase were significantly lower than those of remission phase or control group, and returned to normal control levels after steroid therapy.

CONCLUSION

This study indicates that initial IgE level is associated with steroid responsiveness and disease severity, and cytokine activities may also be related to the pathogenesis of pediatric steroid responsive NS.

Elevated levels of immunoglobulin E may indicate steroid resistance or relapse in adult primary nephrotic syndrome, especially in minimal change nephrotic syndrome

Immunoglobulin E (IgE) antibodies may play a role in the development of kidney diseases that are related to hypersensitivity reactions. Patients with idiopathic nephrotic syndrome often exhibit increased serum IgE levels and this may be related to sensitivity to steroid treatment. In the present study, the serum IgE levels in 120 patients with different types of primary nephrotic syndrome (PNS) were analysed and found to be significantly elevated in cases of minimal change nephrotic syndrome (MCNS) compared with membranous nephropathy or membrano-proliferative glomerulonephritis. No difference in serum IgE level was observed between cases of steroid-sensitive nephrotic syndrome (SSNS) or steroid-resistant nephrotic syndrome, although the serum IgE level was significantly elevated in SSNS patients in relapse compared with SSNS patients in remission. In MCNS patients, 73.6% exhibited SSNS regardless of their serum IgE level at diagnosis. It is concluded that elevated levels of IgE may be a feature of steroid resistance or relapse, indicating prognostic significance in adult PNS, particularly in MCNS.

Minimal change disease: a CD80 podocytopathy?

Minimal change disease is the most common nephrotic syndrome in children. Although the etiology of minimal change disease remains to be elucidated, it has been postulated that it is the result of a circulating T-cell factor that causes podocyte cytoskeleton disorganization leading to increased glomerular capillary permeability and/or changes in glomerular basement membrane heparan sulfate glycosaminoglycans resulting in proteinuria. Minimal change disease has been associated with allergies and Hodgkin disease. Consistent with these associations, a role for interleukin-13 with minimal change disease has been proposed. Furthermore, studies evaluating podocytes also have evolved. Recently, increased expression of CD80 (also termed B7-1) on podocytes was identified as a mechanism for proteinuria. CD80 is inhibited by binding to CTLA-4, which is expressed on regulatory T cells. Recently, we showed that urinary CD80 is increased in minimal change disease patients and limited studies have suggested that it is not commonly present in the urine of patients with other glomerular diseases. Interleukin-13 or microbial products via Toll-like receptors could be factors that induce CD80 expression on podocytes. CTLA-4 appears to regulate CD80 expression in podocytes, and to be altered in minimal change disease patients. These findings lead us to suggest that proteinuria in minimal change disease is caused by persistent CD80 expression in podocytes, possibly initiated by stimulation of these cells by antigens or cytokines.

Elevated serum interleukin-7 level in idiopathic steroid-sensitive nephrotic syndrome

BACKGROUND

Several cytokines have a pathological association with idiopathic steroid-sensitive nephrotic syndrome (ISSNS) in inducing proteinuria or regulating T cells. Because interleukin (IL)-7 plays important roles in regulating T-cell proliferation and sustaining naïve or memory T cells, IL-7 is one of the candidate cytokines in the pathogenesis of ISSNS. Very little is known, however, about the association of IL-7 with ISSNS. To clarify the IL-7 dynamics in children with ISSNS, serum IL-7 level was investigated, from the nephrotic phase before steroid treatment (STx; group A1) to the remission phase with STx (group A2) and without STx (group A3).

METHODS

Eighteen children with ISSNS were included in the present study. A total of 25 paired samples were analyzed for groups A1 and A2, and a total of 10 paired samples for groups A1, A2, and A3 due to recurrence. Two control groups (with normal urinalysis, group B; or with nephrotic syndrome other than ISSNS, group C), matched for age and gender, were also included. Serum cytokine level was measured on bead-based assay.

RESULTS

Each serum IL-7 level in groups A1 and A3 was higher than each serum IL-7 level of groups C and B, respectively. The group A2 serum IL-7 level was higher than that of group A1. There was no statistical significance of serum IL-7 level between group A1 and group A3.

CONCLUSION

Serum IL-7 level was elevated in children with ISSNS regardless of the status of the disease. This brings us one step closer to a better understanding of the pathophysiology of ISSNS in children.

Allergic sensitization in kidney-transplanted patients prevails under tacrolimus treatment

BACKGROUND

Type I allergies have repeatedly been reported after solid organ transplantation despite T cell-targeted immunosuppressive therapy. A causal relationship with tacrolimus has been proposed.

OBJECTIVE

The present study directly compared the occurrence of allergic sensitization and disease under tacrolimus- vs. cyclosporin A-based immunosuppressive therapy.

METHODS

The prevalences of IgE-mediated sensitization and allergy were assessed in a cross-sectional study of kidney-transplanted adults receiving tacrolimus (n = 100) or cyclosporin A (n = 100).

METHODS

included a standardized questionnaire, skin prick test and measurement of total and specific IgE against common nutritive and inhalant allergens. Results The prevalence of sensitization was significantly higher in the tacrolimus- than in the cyclosporin A-treated group (34%, n = 34, vs. 20%, n = 20; P = 0.026). The rate of clinically relevant allergy in patients receiving tacrolimus was twice that in patients receiving cyclosporin A (15%, n = 15, vs. 8%, n = 8; P = 0.12). No other factor (age, serum drug level, concomitant immunosuppressive medication, time since transplantation, underlying disease) was found to have an influence on sensitization or allergy prevalence (logistic regression).

CONCLUSION AND CLINICAL RELEVANCE

Our results suggest that post-transplant immunosuppression with tacrolimus is associated with an increased occurrence of IgE-mediated sensitization and probably manifestation of allergic disease, which has to be treated specifically despite immunosuppressive therapy.

Minimal change disease: a "two-hit" podocyte immune disorder?

Minimal change disease (MCD) is the most common nephrotic syndrome in children and is commonly thought to be a T-cell disorder mediated by a circulating factor that alters podocyte function resulting in massive proteinuria. We suggest that MCD is a "two-hit" disorder. As originally hypothesized by Reiser et al. in 2004, we propose that the initial hit is the induction of CD80 (also known as B7.1) on the podocyte, and that this results in an alteration in shape with actin rearrangement that alters glomerular permeability and causes proteinuria. We propose that CD80 expression may result from either direct binding of the podocyte by cytokines from activated T cells or by activation of podocyte toll-like receptors (TLR) by viral products or allergens. We further hypothesize that under normal circumstances, CD80 expression is only transiently expressed and proteinuria is minimal due to rapid autoregulatory response by circulating T regulatory cells or by the podocyte itself, probably due to the expression of factors [cytotoxic T-lymphocyte-associated (CTLA)-4, interleukin (IL)-10, and possibly transforming growth factor (TGF)-β] that downregulate the podocyte CD80 response. In MCD, however, there is a defect in CD80 podocyte autoregulation. This results in persistent CD80 expression and persistent proteinuria. If correct, this hypothesis may lead to both new diagnostic tests and potential therapeutics for this important renal disease.

Regulation and dysregulation of immunoglobulin E: a molecular and clinical perspective

BACKGROUND

Altered levels of Immunoglobulin E (IgE) represent a dysregulation of IgE synthesis and may be seen in a variety of immunological disorders. The object of this review is to summarize the historical and molecular aspects of IgE synthesis and the disorders associated with dysregulation of IgE production.

METHODS

Articles published in Medline/PubMed were searched with the keyword Immunoglobulin E and specific terms such as class switch recombination, deficiency and/or specific disease conditions (atopy, neoplasia, renal disease, myeloma, etc.). The selected papers included reviews, case reports, retrospective reviews and molecular mechanisms. Studies involving both sexes and all ages were included in the analysis.

RESULTS

Both very low and elevated levels of IgE may be seen in clinical practice. Major advancements have been made in our understanding of the molecular basis of IgE class switching including roles for T cells, cytokines and T regulatory (or Treg) cells in this process. Dysregulation of this process may result in either elevated IgE levels or IgE deficiency.

CONCLUSION

Evaluation of a patient with elevated IgE must involve a detailed differential diagnosis and consideration of various immunological and non-immunological disorders. The use of appropriate tests will allow the correct diagnosis to be made. This can often assist in the development of tailored treatments.

Childhood nephrotic syndrome in Cambodia: an association with gastrointestinal parasites

OBJECTIVES

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

STUDY DESIGN

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

RESULTS

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

CONCLUSIONS

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

Idiopathic nephrotic syndrome and atopy: is there a common link?

Numerous reports during the last 60 years have reported a strong association between idiopathic nephrotic syndrome and atopic disorders. Idiopathic nephrotic syndrome can be precipitated by allergic reactions and has been associated with both aeroallergens (pollens, mold, and dust) and food allergies. Patients with idiopathic nephrotic syndrome also may show increased serum immunoglobulin E (IgE) levels. A review of the literature suggests that although some idiopathic nephrotic syndrome cases may be associated with allergies, evidence that it is a type of allergic disorder or can be induced by a specific allergen is weak. Rather, it is likely that the proteinuria and increased IgE levels in patients with idiopathic nephrotic syndrome are caused by increased levels of interleukin 13 observed in these patients. Recent studies suggest that interleukin 13, a known stimulator of IgE response, may mediate proteinuria in patients with minimal change disease because of its ability to directly induce CD80 expression on the podocyte.

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

BACKGROUND

Corticosteroid-resistant idiopathic nephrotic syndrome (INS) recurs rapidly after transplantation in 30% to 50% of transplant recipients, suggesting the presence of 1 or more circulating factors that alter the glomerular filtration barrier. We investigated the possible role in INS recurrence of soluble ST2 (sST2) protein, a marker of T helper type 2 (T(H)2) cells and a factor predicted to be regulated by the transcription factor c-Maf; involvement of sST2 protein would be consistent with the observation that both T(H)2 cells and c-Maf appear to be activated during INS relapse.

STUDY DESIGN

Retrospective observational study.

SETTING & PARTICIPANTS

Patients with biopsy-proven corticosteroid-resistant INS who had undergone kidney transplantation between September 1983 and April 2007 (n = 71). A control group consisting of proteinuric transplant recipients with kidney failure unrelated to INS (n = 34).

PREDICTOR

Patients who developed INS recurrence after transplantation (n = 31) were compared with those in whom INS did not recur (n = 40) and the control group. Recurrence of INS was defined as urine protein excretion greater than 2 g/d immediately after transplantation that persisted at greater than 1 g/d despite treatment or a kidney graft biopsy showing minimal change glomerulonephritis or focal segmental glomerulosclerosis.

OUTCOMES & MEASUREMENTS

Urine protein excretion in the 3 groups was 5.0 g/d (range, 1.3 to 10.5), 0.14 g/d (range, 0 to 0.46), and 4.3 g/d (range, 3 to 6.2). The sST2 protein was analyzed both quantitatively and qualitatively in patient sera, and its activity was tested in vitro on a mouse podocyte cell line and in vivo in rats.

RESULTS

sST2 protein levels were significantly increased after transplantation in patients with INS recurrence compared with the 2 other groups (617.5 versus 23 pg/mL; P < 0.001 and 158.5 pg/mL; P < 0.01 respectively). However, patients with recurrence expressed a normal sST2 isoform, and the sST2 protein was unable to induce podocyte injury in vitro or trigger proteinuria in rats.

LIMITATIONS

Pretransplantation and posttransplantation sera do not always represent paired samples.

CONCLUSIONS

These data suggest that sST2 protein is a marker of INS recurrence that does not seem to be involved in the development of INS.

New insights into the pathophysiology of idiopathic nephrotic syndrome

Corticoresistant idiopathic nephrotic syndrome (INS) is a glomerulopathy of unknown etiology whose original aspect is its recurrence after kidney transplantation in 30 to 50% of patients with end-stage renal disease. This suggests the involvement of circulating factors that would alter the glomerular filtration barrier, but whose nature remains elusive. Although a T cell immune origin has been suggested, the actual role of these cells in INS recurrence is still unclear. Here we present an 8-year-old patient with corticoresistant INS who developed a recurrence of her initial disease after kidney transplantation. Rituximab therapy was proposed 11 months after transplantation; although no immediate effect was induced, a slow but persistent decrease in proteinuria began a few months after Rituximab infusions despite cessation of plasma exchanges and steroid therapy. The pathophysiology of INS and the putative mechanisms of action of Rituximab are discussed.

Polymorphisms in interleukin-4-related genes in patients with minimal change nephrotic syndrome

Minimal change nephrotic syndrome (MCNS) in children is frequently associated with allergy and immunoglobulin E production. T helper subtype 2 cytokines, such as interleukin (IL)-4 and IL-13, may have an important role in the development of atopy. We investigated the association of genetic variations of IL-4 receptor alpha chain (IL-4Ralpha), IL-13 and signal transducer and activator of transcription 6 (STAT6) genes with MCNS. We analyzed these polymorphisms in 85 Japanese children (55 males, 30 females) with MCNS and 127 healthy controls with neither allergic nor renal diseases. Genomic DNA was extracted from peripheral blood leukocytes. The single nucleotide polymorphisms of IL-4Ralpha (Ile50Val) and IL-13 (R130Q) were detected by primer-specific polymerase chain reaction (PCR) and PCR-restriction fragment length polymorphism analysis, respectively. GT repeat polymorphism in STAT6 gene exon 1 was investigated by fragment length analysis. A significant difference in allelic frequencies in the STAT6 gene was detected between the MCNS and control groups. There was no significant difference between the two groups for genetic variations of IL-4Ralpha and IL-13 genes. We found a significant difference in IL-4Ralpha gene polymorphism between MCNS subgroups divided according to the number of relapses. These results suggested that the genetic variation in the first exon of the STAT6 gene may be associated with a predisposition to MCNS and that the genetic variation in the IL-4Ralpha gene may be associated with its clinical course.

Overexpression of interleukin-13 induces minimal-change-like nephropathy in rats

IL-13 has been implicated in the pathogenesis of minimal-change nephrotic syndrome. This study aimed to investigate the role of IL-13 on the development of proteinuria and expression of podocyte-related genes that are associated with nephrotic syndrome. IL-13 was overexpressed in Wistar rats through transfection of a mammalian expression vector cloned with the rat IL-13 gene, into the quadriceps by in vivo electroporation. Serum IL-13, albumin, cholesterol, and creatinine and urine albumin were measured serially. Kidneys were harvested after day 70 for histology and electron microscopy. Glomerular gene expression of nephrin, podocin, dystroglycan, B7-1, and IL-13 receptor subunits were examined using real-time PCR with hybridization probes and expressed as an index against beta-actin. Protein expression of these molecules was determined by immunofluorescence staining. The IL-13-transfected rats (n = 41) showed significant albuminuria, hypoalbuminemia, and hypercholesterolemia when compared with control rats (n = 17). No significant histologic changes were seen in glomeruli of IL-13-transfected rats. However, electron microscopy showed up to 80% of podocyte foot process fusion. Glomerular gene expression was significantly upregulated for B7-1, IL-4Ralpha, and IL-13Ralpha2 but downregulated for nephrin, podocin, and dystroglycan. Immunofluorescence staining intensity was reduced for nephrin, podocin, and dystroglycan but increased for B7-1 and IL-4Ralpha in IL-13-transfected rats compared with controls. In conclusion, these results suggest that IL-13 overexpression in the rat could lead to podocyte injury with downregulation of nephrin, podocin, and dystroglycan and a concurrent upregulation of B7-1 in the glomeruli, inducing a minimal change-like nephropathy that is characterized by increased proteinuria, hypoalbuminemia, hypercholesterolemia, and fusion of podocyte foot processes.

Atopy in childhood idiopathic nephrotic syndrome

AIM

Aim of the study was to evaluate the immunoallergic pattern and their modulating serum cytokines in children with primary manifestation of nephrotic syndrome, in order to analyse the correlation with disease activity and the outcome of childhood NS.

MATERIALS AND METHODS

We have evaluated 72 children: 58 steroid-sensitive and 14 steroid-resistant; 42 subjects were the healthy controls. In all were measured serum: T cell-subset, cytokines by Th-1, Th-2, total IgE levels and specific IgE antibodies.

RESULTS

Of the 72 children investigated, 35 (48.6%) had either a history of atopy and/or elevated serum IgE; 14 of these children (40%) had clinical sign of an atopic disease (asthma, rhinitis, dermatitis) and 21 (60%) had elevated sIgE. The atopy was more frequent among SS than SRNS patients (52% versus 36%, p<0.05). The CD19 were significantly increased in nephrotic patients compared with controls. IL-4 levels were not different from those in normal control both in SS and SRNS patients, either in relapse than in remission. There was no correlation between the sIgE and IL-4 levels. Therefore, IL-5 and Il-13 levels were significantly higher in SSNS compared to controls, in both pre than posttreatment, and higher in atopic patients. Interestingly, IL-6 and IL-10 levels were significantly increased in SRNS pretreatment compared to posttreatment and controls and, only for IL-10, significantly higher in atopic patients.

CONCLUSION

In our study, only 40% of atopic children had a positive allergic history and 51.4% of the nephrotic children had normal sIgE levels, both pre and posttreatment, indicating different aetiologies, as immune mechanisms, in the pathogenesis of NS. Therefore, specific IgE antibodies were not related to disease activity, suggesting that IgE production might be co-incident in childhood NS. However, the increased production of IL-5 and IL-13 in atopic SSNS may indicate that these cytokines are involved in the enhanced production of sIgE while IL-4 have a role as controlling cytokine.

A case of unfulfilled expectations. Cytokines in idiopathic minimal lesion nephrotic syndrome

Idiopathic minimal lesion nephrotic syndrome (IMLNS) was proposed to be a disorder of T-cell dysfunction by Shalhoub in 1974. The mechanisms by which T-cells increase glomerular permeability have remained elusive (and unproven). There is evidence that IMLNS may be due to a circulating factor released from activated T-cells. In recent years, efforts have been made to identify this pathogenetic cytokine as well as to understand the mechanism(s) for the increased release of this factor. This review attempts to critically analyze the available published data. Using different methodologies, investigators have focused on the production of cytokines in patients with IMLNS during relapse and remission. This has resulted in a plethora of data without definitive conclusions. The pathogenetic cytokine has not been identified, and it is questionable whether there is a Th2 dominance in IMLNS. The review of the available data illustrates the difficulties encountered when one is studying the cytokine secretory pattern in patients with IMLNS. Differences in patient population, type of cells studies, sample preservation, and methodology used to measure cytokines are some of the factors that could account for the disparity of observed results.