Markers of endothelial dysfunction in children with idiopathic nephrotic syndrome

Endothelial Dysfunction in Children With Nephrotic Syndrome: A Cross-Sectional Study

Background Children with nephrotic syndrome (NS) have a higher risk of cardiovascular morbidity. Studies on the evaluation of arterial stiffness and endothelial function and its predictive risk factors in these children are limited. Objective The primary objective of the study was to determine arterial stiffness by measuring carotid intimal medial thickness, flow-mediated dilatation, and physiological parameters in children with nephrotic syndrome to predict the risk of premature atherosclerosis as compared to controls. Participants A total number of 33 children with NS in the age group of 2-14 years in remission and 39 healthy controls were enrolled in the study. Out of 33 children with nephrotic syndrome, five were infrequently relapsing NS, eight were frequently relapsing, 16 were steroid dependent, and four were steroid-resistant NS. Intervention Relevant history, physical examination, anthropometric measurements, and laboratory investigations were done. Carotid intimal medial thickness (cIMT), flow-mediated dilatation (FMD), and other physiological parameters were measured in both children with NS and control groups. Outcome Carotid intimal medial thickness (cIMT), flow-mediated dilatation (FMD), and other physiological parameters were compared between children with NS and healthy controls for detecting arterial stiffness and endothelial dysfunction. Results Dyslipidaemia was seen in more than 50% of children during remission. There was neither significant difference in mean cIMT in the common carotid artery nor FMD between the control and study groups. There was a trend of lower Reactive Hyperemia Index (RHI) in children with NS. Conclusion Dyslipidemia persists even during the remission phase in NS. No statistically significant difference is observed in cIMT and percentage proportionate change in FMD in both the study and control groups. Nevertheless, RHI is notably lower in children with NS. These findings need further validation in future studies.

The role of toll-like receptors (TLRs) and their therapeutic applications in glomerulonephritis

One of the most important features of innate immunity is the presence of a special group of pattern recognition receptors (PRRs) called toll-like receptors (TLRs), which recognize pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs), resulting in a quick and effective immune response to them. Glomerulonephritis (GN) is one of the most important categories of renal disorders characterized by destructive responses of the immune system to the glomerulus. To date, the association of TLRs as important innate immune system members with GN has been one of the topics that attracted the attention of researchers in this field. However, the exact role of these receptors in the immunopathogenesis of GN has not yet been fully discussed. Therefore, this study aims to overview the role of TLRs in GN and the possibility of using them as a potential therapeutic target.

A spectrum of novel anti-vascular endothelial cells autoantibodies in idiopathic nephrotic syndrome patients

Idiopathic nephrotic syndrome (INS) is a common renal disease characterized by disruption of the glomerular filtration barrier. In a previous study, we screened and identified podocyte autoantibodies in nephrotic syndrome patients and proposed the concept of autoimmune podocytopathy. However, circulating podocyte autoantibodies cannot reach podocytes unless glomerular endothelial cells have been damaged. Therefore, we speculate that INS patients may also have autoantibodies against vascular endothelial cells. Sera from INS patients were used as primary antibodies to screen and identify endothelial autoantibodies by hybridization with vascular endothelial cell proteins separated by two-dimensional electrophoresis. The clinical application value and pathogenicity of these autoantibodies were further verified by clinical study and in vivo and in vitro experiments. Nine kinds of autoantibodies against vascular endothelial cells were screened in patients with INS, which can cause endothelial cell damage. In addition, 89% of these patients were positive for at least one autoantibody.

Evaluation of carotid intima media thickness in children with idiopathic nephrotic syndrome

BACKGROUND

Nephrotic syndrome is the one of the commonest renal disorders in children. Children with nephrotic syndrome (NS) are at a high risk of atherosclerosis due to hyperlipidemia, hypertension. Carotid intima media thickness (CIMT) is a surrogate marker for atherosclerosis. This study aimed to evaluate the carotid intima media thickness in children with nephrotic syndrome and its relation to different risk factors.

METHODS

This is an observational case control study that included forty children with nephrotic syndrome and thirty healthy children as controls. The inclusion criteria were: age of 2 years or more with disease duration of minimum of 1 year and glomerular filtration rate > 90 mL/min/1.73m². CIMT was assessed by ultrasound. Lipid profile, protein/creatinine ratio in urine and kidney function tests were done.

RESULTS

The mean CIMT (mm) was significantly higher in patients with NS (0.477 ± 0.04) compared to controls (0.39 ± 0.03) (P < 0.001) even when compared across different age groups. 60% of patients had received non-steroid immunosuppressive therapy. CIMT was significantly higher in patients receiving non-steroid immunosuppressive therapy than those receiving steroids alone. Subsequently, CIMT had significant positive correlation to duration of the disease (p = 0.05), body mass index (BMI) (p = 0.03), number of relapses (p = 0.01) and diastolic blood pressures (p = 0.003).

CONCLUSION

Children with NS had significantly higher CIMT than control group. CIMT was positively correlated to disease duration, number of relapses and BMI. It was significantly higher among patients receiving non-steroid immunosuppressive therapy than those receiving steroids alone.

Minimal Change Disease Is Associated With Endothelial Glycocalyx Degradation and Endothelial Activation

Introduction

Minimal change disease (MCD) is considered a podocyte disorder triggered by unknown circulating factors. Here, we hypothesized that the endothelial cell (EC) is also involved in MCD.

Methods

We studied 45 children with idiopathic nephrotic syndrome (44 had steroid sensitive nephrotic syndrome [SSNS], and 12 had biopsy-proven MCD), 21 adults with MCD, and 38 healthy controls (30 children, 8 adults). In circulation, we measured products of endothelial glycocalyx (EG) degradation (syndecan-1, heparan sulfate [HS] fragments), HS proteoglycan cleaving enzymes (matrix metalloprotease-2 [MMP-2], heparanase activity), and markers of endothelial activation (von Willebrand factor [vWF], thrombomodulin) by enzyme-linked immunosorbent assay (ELISA) and mass spectrometry. In human kidney tissue, we assessed glomerular EC (GEnC) activation by immunofluorescence of caveolin-1 (n = 11 MCD, n = 5 controls). In vitro, we cultured immortalized human GEnC with sera from control subjects and patients with MCD/SSNS sera in relapse (n = 5 per group) and performed Western blotting of thrombomodulin of cell lysates as surrogate marker of endothelial activation.

Results

In circulation, median concentrations of all endothelial markers were higher in patients with active disease compared with controls and remained high in some patients during remission. In the MCD glomerulus, caveolin-1 expression was higher, in an endothelial-specific pattern, compared with controls. In cultured human GEnC, sera from children with MCD/SSNS in relapse increased thrombomodulin expression compared with control sera.

Conclusion

Our data show that alterations involving the systemic and glomerular endothelium are nearly universal in patients with MCD and SSNS, and that GEnC can be directly activated by circulating factors present in the MCD/SSNS sera during relapse.

Molecular Mechanisms of Proteinuria in Minimal Change Disease

Minimal change disease (MCD) is the most common type of idiopathic nephrotic syndrome in childhood and represents about 15% cases in adults. It is characterized by massive proteinuria, edema, hypoalbuminemia, and podocyte foot process effacement on electron microscopy. Clinical and experimental studies have shown an association between MCD and immune dysregulation. Given the lack of inflammatory changes or immunocomplex deposits in the kidney tissue, MCD has been traditionally thought to be mediated by an unknown circulating factor(s), probably released by T cells that directly target podocytes leading to podocyte ultrastructural changes and proteinuria. Not surprisingly, research efforts have focused on the role of T cells and podocytes in the disease process. Nevertheless, the pathogenesis of the disease remains a mystery. More recently, B cells have been postulated as an important player in the disease either by activating T cells or by releasing circulating autoantibodies against podocyte targets. There are also few reports of endothelial injury in MCD, but whether glomerular endothelial cells play a role in the disease remains unexplored. Genome-wide association studies are providing insights into the genetic susceptibility to develop the disease and found a link between MCD and certain human haplotype antigen variants. Altogether, these findings emphasize the complex interplay between the immune system, glomerular cells, and the genome, raising the possibility of distinct underlying triggers and/or mechanisms of proteinuria among patients with MCD. The heterogeneity of the disease and the lack of good animal models of MCD remain major obstacles in the understanding of MCD. In this study, we will review the most relevant candidate mediators and mechanisms of proteinuria involved in MCD and the current models of MCD-like injury.

Thrombotic microangiopathy triggered by podocytopathy

Thrombotic microangiopathy (TMA) is a rare group of diseases characterized by microangiopathic hemolytic anemia, thrombocytopenia, and target organ damage. It can be divided into primary and secondary TMA. Herein we report a case of TMA associated to a primary glomerular disease. We report the case of a 31-year-old Black male from Cape Verde admitted in March 2018 with nephrotic syndrome and upper gastrointestinal bleeding, the latter due to severe erythematous gastritis. He was discharged after clinical stabilization. The patient came to Portugal 8 months later. On admission, he presented with rapid deterioration of kidney function and hyperkalemia. The etiologic study revealed microangiopathic hemolytic anemia, nephrotic syndrome and microscopic hematuria. Immunologic study and viral serology were negative. ADAMTS13 activity and inhibitor testing were within normal range, genetic complement evaluation showed CFH-H3 in homozygosity, functional complement studies revealed decreased function of alternative pathway. Kidney biopsy was consistent with the diagnosis of TMA, and electron microscopy was compatible with minimal change disease. Patient underwent plasmapheresis with resolution of hemolysis, fluid overload and recovery of renal function. Two months later, he presented with nephrotic syndrome and started prednisolone with remission. Six months later, the nephrotic syndrome relapsed, and it became steroid-, MMF-, and rituximab-resistant. Tacrolimus was initiated, achieving partial remission. Atypical hemolytic uremic syndrome is an uncommon disease and is rarely reported as secondary to glomerular diseases. This case showcases the challenges regarding treatment options in a resistant glomerulopathy and the implications of therapeutic choices and kidney outcomes with the coexisting TMA.

Assessment of Carotid Intima Media Thickness and Left Ventricular Mass Index in Children with Idiopathic Nephrotic Syndrome

BACKGROUND

Children with nephrotic syndrome (NS) are at a greater risk of atherosclerosis due to recurrent exposures to hyperlipidemia, hypertension, and immunosuppressive medications. CIMT (carotid intima media thickness) is a reliable marker for assessment of atherosclerosis of large and medium-sized blood vessels; endothelial dysfunction and increased CIMT usually precede the development of cardiovascular diseases. Some manifestations of NS, like proteinuria and hyperlipidemia, are associated with an increased risk of cardiac morbidity and mortality. The aim of the current study was to evaluate the carotid intima media thickness and LVM (left ventricular mass) thickness in children with nephrotic syndrome.

SUBJECTS AND METHODS

Eighty-one children with nephrotic syndrome and 100 healthy children as controls were enrolled in the study. The inclusion criteria were: disease duration of minimum of 12 months, glomerular filtration rate >60mL/min/1.73m 2 and children aged two years or more at the time of study. CIMT and left ventricular mass index, lipid profile, protein/creatinine ratio in urine and kidney function tests were done for cases and controls after approval of internal ethical committee.

RESULTS

The mean CIMT (mm) was significantly higher in NS (0.51± 0.12) compared to controls (0.42± 0.09) (P <0.001). LVM and LVM Index were significantly higher in NS than controls (p< 0.001, for both). Subsequently, CIMT was significantly correlated to duration of the disease (p< 0.001), LVM index was significantly correlated with duration of the disease, body mass index (BMI), blood pressures and triglycerides level (p< 0.05).

CONCLUSION

Children with NS are at increasing risk to develop atherosclerosis as measured by CIMT. LVM was significantly higher in NS and positively correlated to BP, disease duration, triglyceride levels and BMI.

The underestimated burden of monogenic kidney disease in adults waitlisted for kidney transplantation

Purpose

Chronic kidney disease (CKD) is a major health-care burden. Increasing evidence suggests that a considerable proportion of patients are affected by a monogenic kidney disorder.

Methods

In this study, the kidney transplantation waiting list at the Charité was screened for patients with undetermined cause of CKD. By next-generation sequencing (NGS) we targeted all 600 genes described and associated with kidney disease or allied disorders.

Results

In total, 635 patients were investigated. Of these, 245 individuals had a known cause of CKD (38.5%) of which 119 had a proven genetic disease (e.g., ADPKD, Alport). The other 340 patients (53.5%) were classified as undetermined diagnosis, of whom 87 had kidney failure (KF) onset <40 years. To this latter group genetic testing was offered as well as to those patients (n = 29) with focal segmental glomerulosclerosis (FSGS) and all individuals (n = 21) suspicious for thrombotic microangiopathy (TMA) in kidney biopsy. We detected diagnostic variants in 26 of 126 patients (20.6%) of which 14 of 126 (11.1%) were pathogenic or likely pathogenic. In another 12 of 126 (9.5%) patients, variants of unknown significance (VUS) were detected.

Conclusion

Our study demonstrates the diagnostic value of comprehensive genetic testing among patients with undetermined CKD.

Glomerular endothelial cells and podocytes can express CD80 in patients with minimal change disease during relapse

BACKGROUND

Urinary CD80 has emerged as potential biomarker in idiopathic nephrotic syndrome (INS). However, its cellular source remains controversial. The aim of the study was to assess whether CD80 is truly expressed by glomerular cells in INS patients during relapse and in the LPS mouse model of podocyte injury.

METHODS

The presence of CD80 in glomeruli was evaluated by combining immunostaining, immunogold labeling, and in situ hybridization techniques.

RESULTS

CD80 was present along the surface of glomerular endothelial cells (GEC) and rarely in podocytes in six of nine minimal change disease (MCD) patients in relapse, two of eleven patients with focal segmental glomerulosclerosis in relapse, and absent in controls. In mice, CD80 was upregulated at mRNA and protein level in GEC and podocytes, in a similar pattern to that seen in MCD patients.

CONCLUSIONS

Glomerular endothelial cells and podocytes can express CD80 in patients with MCD during relapse. A better understanding of the role of CD80 in glomerular cells may provide further insights into the mechanisms of proteinuria in INS.

Infection-provoked reversible posterior leukoencephalopathy syndrome in an adult with nephrotic syndrome: a case report

Background

Reversible posterior leukoencephalopathy syndrome (RPLS) is a rare and heterogeneous clinico-neuroradiological syndrome characterized by headache, altered mental status, seizures, and visual disturbances. Hypertension and immunosuppression are two of the main factors that predispose an individual to RPLS. However, RPLS can develop when no major risk factors are present. RPLS has been reported in pediatric nephrotic patients, but rarely in adults.

Case presentation

A 42-year-old Asian woman with nephrotic syndrome presented with seizures, headaches, and nausea. Her blood pressure was controlled, and no immunosuppressants had been prescribed. All symptoms and tests indicated RPLS following infection with pneumonia, which was successfully treated by immediate administration antibiotic and anti-epileptic medications. Seizures did not recur during a 2-year follow-up period.

Conclusions

When patients with nephrotic syndrome have an infection, RPLS symptoms should be investigated thoroughly. With early diagnosis and appropriate treatment of RPLS, morbidity and mortality can be prevented.

Augmentation index, a predictor of cardiovascular events, is increased in children and adolescents with primary nephrotic syndrome

BACKGROUND

Arterial stiffness is associated with an increased risk of cardiovascular diseases. Augmentation index (AIx@75), a measure of arterial stiffness and wave reflection, has not been evaluated in patients with primary nephrotic syndrome (PNS). We investigated whether central and peripheral vascular profiles, hemodynamic parameters, and biochemical tests are associated with AIx@75 in PNS patients.

METHODS

This observational study involved 38 children and adolescents with PNS (12.14 ± 3.65 years) and 37 healthy controls (13.28 ± 2.80 years). Arterial stiffness and vascular and hemodynamic parameters were measured noninvasively using the Mobil-O-Graph® (IEM, Stolberg, Germany). In the PNS group, biochemical tests and corticosteroid dosage/treatment time were analyzed.

RESULTS

Peripheral and central systolic blood pressure (SBPp, SBPc) Z-scores were significantly higher in the PNS patients. AIx@75 was significantly higher in the PNS patients (25.14 ± 9.93%) than in controls (20.84 ± 7.18%). In the control group, AIx@75 negatively correlated with weight (r = - 0.369; p = 0.025), height (r = - 0.370; p = 0.024), and systolic volume/body surface (r = - 0.448; p = 0.006). In the PNS group, a univariate linear correlation showed that AIx@75 negatively correlated with weight (r = - 0.360; p = 0.027), height (r = 0.381; p = 0.18), and systolic volume/body surface (r = - 0.447; p < 0.002) and positively with the Z-score of SBPp (r = 0.407; p = 0.011), peripheral diastolic blood pressure (DBPp, r = 0.452; p = 0.004), SBPc (r = 0.416; p = 0.009), DBPc (r = 0.407; p = 0.011), triglycerides (r = 0.525; p = 0.001), and cholesterol [total (r = 0.539; p < 0.001), LDLc (r = 0.420; p = 0.010), and non-HDLc (r = 0.511; p = 0.001)].

CONCLUSIONS

Early abnormalities of AIx@75 and vascular parameters suggest that patients with PNS, even in stable condition, present subclinical indicators for the development of cardiovascular disease.

Relationship between soluble urokinase-type plasminogen activator receptor and serum biomarkers of endothelial activation in patients with idiopathic nephrotic syndrome

Background

Serum levels of soluble urokinase-type plasminogen activator receptor (suPAR) are high in some patients with idiopathic nephrotic syndrome (INS). Given that suPAR constitutes a predictor of vascular disease and has been associated with endothelial dysfunction, we hypothesized that suPAR levels are related to endothelial activation or dysfunction in INS patients. The aims of this study were to evaluate the relationship between serum concentrations of endothelial biomarkers and suPAR in patients with different histological patterns of INS and healthy controls, and to determine the demographic, clinical and biochemical characteristics of INS patients that influence suPAR serum levels.

Methods

This observational, cross-sectional study included patients with INS, diagnosed with minimal change disease (MCD), focal segmental glomerulosclerosis (FSGS) or membranous nephropathy (MN) by renal biopsy. Patient demographic, clinical and biochemical characteristics were recorded and blood samples were obtained at the time of diagnosis. Measurements of suPAR and endothelial molecules via serum levels were performed using Enzyme-Linked ImmunoSorbent Assay kits.

Results

Patients with nephrotic syndrome (n = 152) caused by FSGS, MCD or MN had increased circulating levels of endothelial markers. suPAR levels positively correlated with age and the serum levels of almost all endothelial markers. Generally, endothelial cell molecules positively correlated with each other. suPAR levels were not associated with the histopathological pattern of INS.

Conclusions

In patients with INS secondary to FSGS, MCD and NM, circulating levels of suPAR are independent of the primary renal disease, and significantly associated with age, glomerular filtration rate and the levels of various endothelial markers.

Cardiovascular outcomes of Nephrotic syndrome in childhood (CVONS) study: a protocol for prospective cohort study

BACKGROUND

Nephrotic syndrome (NS) is characterized by dyslipidemia which is a well-known risk factor for atherogenesis. Atherosclerosis in childhood is mostly subclinical and endothelial dysfunction is known to precede this. Evidence for screening for endothelial dysfunction and cardiovascular risk factors and early identification of premature onset of atherosclerosis in childhood NS remains tenuous in the absence of well-designed prospective studies addressing cardiovascular comorbidity in NS. The objective of our study is to examine endothelial dysfunction and short-term cardiovascular outcomes in a carefully phenotyped cohort of patients with Nephrotic syndrome as compared to healthy controls.

METHODS

In a multi-centric prospective cohort study, 70 Steroid Resistant NS (SRNS), 70 Steroid Sensitive (SSNS) patients along with 70 Healthy Controls are being recruited. After a baseline assessment of functional and structural status of heart (2D Echocardiography), arteries (Carotid Doppler and Intima Media Thickness measurements) and microcirculation [a combination of 2D Echocardiography, Laser Doppler Flowmetry (LDF) and Brachial Artery Flow mediated dilation (FMD) and Nail Fold Capillaroscopy (NFC)], the patients are being investigated for endothelial dysfunction. Venous blood sample (15 ml) is being collected for routine investigations and assay of biochemical endothelial markers through Flow Cytometry. The patients will be followed up at 12 months and 24 months after the recruitment to look for any change from baseline period.

DISCUSSION

This study will able to provide a better understanding of the epidemiology of endothelial dysfunction and associated subclinical cardiovascular co-morbidity in childhood NS. Findings on characterization of prevalence of endothelial dysfunction and subclinical markers may be used to design future randomized controlled trials for evaluating the efficacy of preventive and therapeutic interventions in reducing the incidence of cardiovascular disease.

Thrombomodulin as a New Marker of Endothelial Dysfunction in Chronic Kidney Disease in Children

Endothelial dysfunction (ED) and oxidative stress are potential new pathomechanisms of cardiovascular diseases in patients with chronic kidney disease (CKD). The aim of the study was to assess the association between endothelial dysfunction, oxidative stress biomarkers, and cardiovascular risk factors in children with CKD. Serum oxidized LDL (oxLDL), protein carbonyl group, urea, creatinine, cystatin C, thrombomodulin, asymmetric dimethylarginine (ADMA), von Willebrand factor, brain natriuretic peptide (BNP), lipids, high sensitivity C-reactive protein, intercellular adhesion molecule-1 levels, and albuminuria were measured. Anthropometric, ambulatory blood pressure (BP) measurements and echocardiography were performed. The studied group consisted of 59 patients aged 0.7–18.6 (mean 11.1) years with stages 1 to 5 CKD. Thrombomodulin strongly correlated with creatinine (R = 0.666; p < 0.001), cystatin C (R = 0.738; p < 0.001), BNP (R = 0.406; p = 0.001), ADMA (R = 0.353; p = 0.01), oxLDL (R = 0.340; p = 0.009), 24-hour systolic (R = 0.345; p = 0.011) and mean (R = 0.315; p < 0.05) BP values, and left ventricular mass index (LVMI, R = 0.293; p = 0.024) and negatively with estimated glomerular filtration rate (R = −0.716; p < 0.001). In children with CKD, TM strongly depended on kidney function parameters, oxLDL levels, and 24-hour systolic and mean BP values. Thrombomodulin seems to be a valuable marker of ED in CKD patients, correlating with CKD stage as well as oxidative stress, BP values, and LVMI.

Characteristics of lipid metabolism including serum apolipoprotein M levels in patients with primary nephrotic syndrome

Background

Apolipoprotein M (apoM) is a 26-kD apolipoprotein that is mainly expressed in specific cell types, such as human liver parenchymal cells and kidney proximal renal tubular epithelial cells. ApoM can regulate the formation of pre-β-HDL and the reverse cholesterol transport and thus plays an important role in the metabolism of lipids and lipoproteins, meaning that it can affect the development of lipid metabolism disorders. Significantly elevated serum apoM levels are detected in patients with hyperlipidemia. However, few studies have shown how apoM is expressed in primary nephrotic syndrome (PNS), which is often accompanied with hyperlipidemia, and the underlying mechanism is poorly understood. This study was aimed at examining the apoM levels in patients with PNS and at determining the effects of PNS on serum apoM levels in these patients.

Methods

This study included patients with hyperlipidemia (n = 37), the PNS with hyperlipidemia group (n = 62), PNS without hyperlipidemia group (n = 33), and healthy controls (n = 73). The age and body–mass index (BMI) matched among the groups of participants. Their serum apoM concentrations were measured by an enzyme-linked immunosorbent assay. Serum levels of conventional lipids and renal function indices were assessed using an automatic biochemical analyzer. The data were analyzed by means of Pearson’s correlation coefficient (continuous variables) or Student’s t test (mean differences).

Results

The average serum apoM concentrations were higher in the hyperlipidemia group (61.1 ± 23.2 mg/L, P = 0.004) than in the healthy controls (31.6 ± 18.92 mg/L). The serum apoM concentrations were lower in the PNS with hyperlipidemia group (25.1 ± 16.31 mg/L, P = 0.007) and in the PNS without hyperlipidemia group (21.00 ± 17.62 mg/L, P = 0.003) than in the healthy controls. The serum apoM concentrations in the PNS with hyperlipidemia group did not differ significantly from those in the PNS without hyperlipidemia group (P = 0.083). Moreover, serum apoM levels positively correlated with serum high-density lipoprotein cholesterol (HDL-C) and apoA1 levels and negatively correlated with proteinuria in PNS patients (r = 0.458, P = 0.003; r = 0.254, P = 0.022; r = −0.414, P = 0.028).

Conclusion

Serum apoM concentrations are higher in patients with hyperlipidemia than in healthy controls. Low serum apoM levels in patients with PNS are likely caused by PNS.

Methods to evaluate arterial structure and function in children - State-of-the art knowledge

BACKGROUND

With increasing rates of hypertension, obesity, and diabetes in the pediatric population, wide available, and reproducible methods are necessary to evaluate arterial structure and function in children and adolescents.

METHODS

MEDLINE/Pubmed was searched for articles published in years 2012-2017 on methodology of, current knowledge on, and limitations of the most commonly used methods to evaluate central, proximal and coronary arteries, as well as endothelial function in pediatric patients.

RESULTS

Among 1528 records screened (including 1475 records from years 2012 to 2017) 139 papers were found suitable for the review. Following methods were discussed in this review article: ultrasound measurements of the intima-media thickness, coronary calcium scoring using computed tomography, arterial stiffness measurements (pulse wave velocity and pulse wave analysis, carotid artery distensibility, pulse pressure, and ambulatory arterial stiffness index), ankle-brachial index, and methods to evaluate vascular endothelial function (flow-mediated vasodilation, peripheral arterial tonometry, Doppler laser flowmetry, and cellular and soluble markers of endothelial dysfunction).

CONCLUSIONS

Ultrasonographic measurement of carotid intima-media thickness and measurement of pulse wave velocity (by oscillometry or applanation tonometry) are highly reproducible methods applicable for both research and clinical practice with proved applicability for children aged ≥6 years or with height ≥120cm. Evaluation of ambulatory arterial stiffness index by ambulatory blood pressure monitoring is another promising option in pediatric high-risk patients. Clearly, further studies are necessary to evaluate usefulness of these and other methods for the detection of subclinical arterial damage in children.

Thrombotic Microangiopathy in Inverted Formin 2-Mediated Renal Disease

The demonstration of impaired C regulation in the thrombotic microangiopathy (TMA) atypical hemolytic uremic syndrome (aHUS) resulted in the successful introduction of the C inhibitor eculizumab into clinical practice. C abnormalities account for approximately 50% of aHUS cases; however, mutations in the non-C gene diacylglycerol kinase-ε have been described recently in individuals not responsive to eculizumab. We report here a family in which the proposita presented with aHUS but did not respond to eculizumab. Her mother had previously presented with a post-renal transplant TMA. Both the proposita and her mother also had Charcot-Marie-Tooth disease. Using whole-exome sequencing, we identified a mutation in the inverted formin 2 gene (INF2) in the mutational hotspot for FSGS. Subsequent analysis of the Newcastle aHUS cohort identified another family with a functionally-significant mutation in INF2 In this family, renal transplantation was associated with post-transplant TMA. All individuals with INF2 mutations presenting with a TMA also had aHUS risk haplotypes, potentially accounting for the genetic pleiotropy. Identifying individuals with TMAs who may not respond to eculizumab will avoid prolonged exposure of such individuals to the infectious complications of terminal pathway C blockade.

Blood concentration of aminothiols in children with relapse of nephrotic syndrome

BACKGROUND

The role of idiopathic nephrotic syndrome (INS) in the pathogenesis of atherosclerosis in childhood has not been clearly elucidated. However, antioxidative defense in INS is thought to be imbalanced. This study aimed to assess the changes of plasma concentration of selected aminothiols in the blood of children with INS at various stages of the disease.

METHODS

This cross-sectional study was conducted in 125 children aged 2-18 years. The children were divided into 4 groups: group A, early relapse (n=37); group B, early remission for 4-6 weeks from the onset (n=37); group C, late steroid-free remission (n=31); and group D, long-term remission for 2-5 years (n=20). Control group (E) consisted of 30 age- and gender-matched healthy children. The study protocol comprised an analysis of plasma concentrations of glutathione, homocysteine, cysteine and cysteinylglycine by high-performance liquid chromatography. Fractions of protein-bound and free aminothiols were measured. Endothelial injury was assessed by thrombomodulin, PAI-1 concentration, and von Willebrand factor activity.

RESULTS

The children with INS had unbalanced aminothiol metabolism only in relapse and early remission, that shifted towards increased oxidative processes. Administration of cyclosporine A caused a significant increase in homocysteine and cysteine concentration. Changes in aminothiol metabolism were significantly related to endothelial injury.

CONCLUSIONS

The findings of this study may be helpful in elucidating the pathogenesis of premature atherosclerosis in patients with INS refractory to the treatment or in the case of frequent relapse.

Paraoxonase Activity and Lipid Profile in Paediatric Nephrotic Syndrome: A Cross-sectional Study

INTRODUCTION

Dyslipidaemia of Nephrotic Syndrome (NS) is known to be linked to oxidative reactions and atherosclerosis. Paraoxonase (PON1) has been implicated in the prevention of Low Density Lipoprotein (LDL) lipid peroxidation and also degrades biologically active oxidised lipids in lipoprotein.

AIM

The present study was taken up to assess PON1 levels in paediatric nephrotic syndrome and also to see if any correlation exists between lipid parameters and PON1.

MATERIALS AND METHODS

This study consists of Group 1 with 40 cases of NS in the age group of 2-14 years and Group 2 with 40 age and sex matched healthy controls. Lipid profile and paraoxonase activity was measured in serum samples of both the groups.

RESULTS

Statistical analysis by student's t-test showed that the mean levels of Total Cholesterol, Trigylycerides, LDL, and VLDL were significantly increased in Group 1 when compared to Group 2 (p <0.001). The mean levels of HDL were similar in both groups. The levels of PON1 were significantly lowered in Group 1 when compared to Group 2. Correlation studies showed no significant correlation between lipid profile and PON1.

CONCLUSION

Cases have atherosclerotic dyslipidaemia and significantly decreased PON1 activity. Decreased PON1 may lead to increased oxidation of LDL accelerating the process of atherosclerosis.

Remission of aHUS neurological damage with eculizumab

Atypical haemolytic uraemic syndrome (aHUS) is a rare disease characterized by haemolytic microangiopathic anaemia, thrombocytopaenia and acute onset of renal failure, in the absence of Escherichia coli infection. Renal damage usually progresses to end-stage renal disease (ESRD), sometimes being accompanied by signs of extrarenal thrombotic microangiopathy (TMA). We report a case of full neurological and haematological recovery after eculizumab treatment in a patient with ESRD secondary to chronic aHUS refractory to plasmatherapy while she was under dialysis. It highlights the use of eculizumab for controlling extrarenal manifestations of aHUS in this population.

Podocyte dysfunction in atypical haemolytic uraemic syndrome

Genetic or autoimmune defects that lead to dysregulation of the alternative pathway of complement have been associated with the development of atypical haemolytic uraemic syndrome (aHUS), which is characterized by thrombocytopenia, haemolytic anaemia and acute kidney injury. The relationship between aHUS, podocyte dysfunction and the resultant proteinuria has not been adequately investigated. However, the report of mutations in diacylglycerol kinase ε (DGKE) as a cause of recessive infantile aHUS characterized by proteinuria, highlighted podocyte dysfunction as a potential complication of aHUS. DGKE deficiency was originally thought to trigger aHUS through pathogenetic mechanisms distinct from complement dysregulation; however, emerging findings suggest an interplay between DGKE and complement systems. Podocyte dysfunction with nephrotic-range proteinuria can also occur in forms of aHUS associated with genetic or autoimmune complement dysregulation without evidence of DGKE mutations. Furthermore, proteinuric glomerulonephritides can be complicated by aHUS, possibly as a consequence of podocyte dysfunction inducing endothelial injury and prothrombotic abnormalities.

Case series of thromboembolic complications in childhood nephrotic syndrome: Hacettepe experience

BACKGROUND

The aim of this study was to describe the incidence and contributory risk factors for thromboembolic complications in children with nephrotic syndrome (NS) and thrombosis.

METHODS

Among 188 children with the diagnosis of NS (80 girls; mean age: 12.6 ± 5.4 years) followed up in our hospital for the last 5 years, 17 (9.0 %) children (16 boys) identified as having thromboembolic complications. All 17 children with NS and thrombosis were screened for laboratory risk factors for thrombosis. The diagnosis was confirmed by cranial magnetic resonance imaging, doppler ultrasonography, and echocardiography.

RESULTS

Among 17 children with thrombosis, 14 (82.3 %) were found to have focal segmental glomerulosclerosis (FSGS) as underlying pathology by renal biopsy. The mean age of the thrombotic children was 4.5 ± 3.2 years at the diagnosis of NS and that was 7.1 ± 4.9 years at the time of thrombosis. The mean time from NS diagnosis to the first thrombosis development was 2.6 ± 2.3 years. Thrombosis occurred during the first year of NS in 9/17 (52.9 %) children. Most of the children (88.2 %) had venous thrombosis. Among the screened risk factors, high factor VIII level (64.7 %) was the leading factor followed by decreased antithrombin III level (29.4 %). Furthermore, 4 children had central venous catheters and 2 had infection as clinical risk factors for thrombosis.

CONCLUSION

In this case series, subtype of FSGS, active disease state of NS, central venous catheters, and some inherited and acquired thrombotic risk factors have been identified as contributory factors for the development of thrombosis in children with NS.

Subclinical cardiovascular disease and its association with risk factors in children with steroid-resistant nephrotic syndrome

BACKGROUND

The aim of this study was to evaluate the presence of subclinical cardiovascular disease (CVD) and its relation to risk factors in pediatric patients with steroid-resistant nephrotic syndrome (NS).

METHODS

Thirty-seven patients with normal renal function were compared with 22 healthy controls regarding the presence of subclinical CVD. Measurements included aortic pulse wave velocity (PWV), carotid intima media thickness (IMT), and left ventricular mass (LVM). Patients were additionally assessed for blood pressure (BP) pattern and the presence of hypertension by 24-h ambulatory blood pressure monitoring.

RESULTS

Compared with the controls, patients had significantly higher mean aortic PWV-standard deviation scores (SDS), mean carotid IMT-SDS, and LVM index (p < 0.001 for all). Increased aortic PWV was noted in 5 % of patients, increased carotid IMT in 22 %, and increased LVM index in 19 %. Five patients (14 %) were hypertensive, and mean BP indexes, SDS, and BP loads during nighttime were significantly higher than those during daytime (p < 0.001 for all). Multivariate analysis revealed a significant relationship between PWV-SDS and ferritin (R(2) = 0.269, p = 0.006) and between carotid IMT-SDS and proteinuria (R(2) = 0.141, p = 0.022). The LVM index was independently associated only with higher body mass index SDS (R(2) = 0.317, p < 0.001). In addition, six patients (16 %) had multiple abnormal subclinical CVD markers, and increased subclinical CVD risk was independently associated only with higher low-density lipoprotein cholesterol (R(2) = 0.292, p = 0.044).

CONCLUSIONS

Based on these results, steroid-resistant NS children generally are at high risk of cardiovascular complications, but the increased risk is likely to be multifactorial.

Biomarkers of endothelial dysfunction in patients with primary focal segmental glomerulosclerosis

AIM

Endothelial dysfunction occurs in nephrotic syndrome (NS) and may constitute a link between NS and vascular complications. Focal segmental glomerulosclerosis (FSGS) is a common cause of NS. This study aimed to assess endothelial markers at different stages of FSGS and define whether they were associated with thromboembolic complications and disease activity.

METHODS

Forty-four patients with nephrotic-range proteinuria and biopsy-proven primary FSGS were included in this study. Nine of them had concurrent thromboembolisms. Thirty-two sex- and age- matched healthy volunteers served as controls. Endothelial markers including circulating endothelial cells (CECs), soluble thrombomodulin (sTM), von Willebrand factor (vWf), soluble vascular cell adhesion molecule-1 (sVCAM-1) and sE-selectin were assessed at the commencement of the study in all participants and were repeated at 2, 6 and 12 months of follow-up in patients without thromboembolisms.

RESULTS

Patients with FSGS during active stage showed significantly higher levels of CECs, sTM, vWf, sVCAM-1 and sE-selectin when compared with controls. Moreover, patients with thromboembolisms had higher CECs and vWf than those without thromboembolisms. In patients without thromboembolisms, endothelial markers except sE-selectin had inverse correlations with serum albumin and were positively related to cholesterol. Multiple analyses showed that cholesterol and serum albumin were independent predictors of CECs and sTM, and vWf and sVCAM-1, respectively. At follow-up, these markers systematically decreased as the disease went into remission, but the increase in vWf and sVCAM-1 persisted even in patients obtaining complete remission for nearly a year. In patients with no response, levels of endothelial markers exhibited no obvious change.

CONCLUSION

Patients with FSGS had elevated markers of endothelial dysfunction, which were largely related to the activity of the disease. Meanwhile, levels of CECs and vWf were higher in patients concurrent with thromboembolisms.

Native nephrectomy prior to pediatric kidney transplantation: biological and clinical aspects

BACKGROUND

Pre-transplant nephrectomy is performed to reduce risks to graft and recipient. The aims of this study were to evaluate (1) indications, surgical approach, and morbidity of native nephrectomy and (2) the effects of kidney removal on clinical and biological parameters.

METHODS

This study was designed as a single-center retrospective cohort study in which 49 consecutive patients with uni- or bilateral native nephrectomies were identified from a total of 126 consecutive graft recipients in our pediatric kidney transplantation database between 1992 and 2011. Demographic, clinical, and laboratory details were extracted from charts and electronic records, including operation reports and pre- and post-operative clinic notes.

RESULTS

Of the 49 nephrectomized patients, 47% had anomalies of the kidneys and urinary tract, 22% had cystinosis, 12% had focal segmental glomerulosclerosis, and 6% had congenital nephrotic syndrome. Nephrectomy decisions were based on clinical judgment, taking physiological and psychosocial aspects into consideration. Nephrectomy was performed in patients with polyuria (>2.5 ml/kg/h) and/or large proteinuria (>40 mg/m(2)/h), recurrent urinary tract infection or (rarely) hypertension. Urine output decreased from (median) 3.79 to 2.32 ml/kg/h (-34%), and proteinuria from 157 to 100 mg/m(2)/h (-40%) after unilateral nephrectomy (p=0.005). After bilateral nephrectomy, serum albumin, protein and fibrinogen concentrations normalized in 93, 73, and 55% of nephrectomized patients, respectively. Clinically relevant procedure-related complications (peritoneal laceration, hematoma) occurred in five patients.

CONCLUSION

In summary, we demonstrate quantitatively that native nephrectomy prior to transplantation improved serum protein levels and anticipated post-transplant fluid intake needs in select children, reducing the risk of graft hypoperfusion and its postulated consequences for graft outcome.

Reduced serum fetuin-A in nephrotic children: a consequence of proteinuria?

BACKGROUND

The extracellular protein fetuin-A is a potent soluble inhibitor of calcification, and its deficiency has been associated with vascular calcification in dialysis patients. In proteinuric patients, significant urinary losses of fetuin-A may cause low serum fetuin-A levels.

METHODS

In a cross-sectional study, urinary/serum concentrations of fetuin-A were investigated in proteinuric children with glomerular diseases and preserved renal function (n = 58) in comparison to healthy controls (n = 246).

RESULTS

Mean fetuin-A serum concentrations were clearly reduced in children with nephrotic syndrome (0.25 ± 0.14 g/l, p < 0.001), slightly reduced in children with large proteinuria (0.39 ± 0.15 g/l, p < 0.05), and comparable to controls in those with mild proteinuria (0.45 ± 0.14 vs. 0.46 ± 0.12 g/l). Fetuin-A was positively correlated with serum protein (r = 0.58), albumin (r = 0.57), and calcium (r = 0.64), but negatively correlated with proteinuria (r = -0.41), albuminuria (r = -0.46), and urinary fetuin-A excretion (r = -0.48; each p < 0.001). The fractional excretion of fetuin-A was significantly associated with the degree of proteinuria and serum fetuin-A levels. However, the urinary loss of fetuin-A and albumin in nephrotic children differed by three orders of magnitude and the mean fractional excretion of fetuin-A was only 1/10 of that of albumin (0.016 ± 0.029 vs. 0.162 ± 0.403%; p < 0.001).

CONCLUSIONS

Fetuin-A is clearly reduced in children with nephrotic syndrome and associated with the degree of hypoalbuminemia. This is due to urinary fetuin-A loss and/or reduced hepatic synthesis. Persistent fetuin-A deficiency may have an impact on cardiovascular morbidity in nephrotic children.