PROGRESS STUDY: Progression of chronic kidney disease in children and heat shock proteins.

Various molecular and cellular processes are involved in renal fibrosis, such as oxidative stress, inflammation, endothelial cell injury, and apoptosis. Heat shock proteins (HSPs) are implicated in the progression of chronic kidney disease (CKD). Our aim was to evaluate changes in urine and serum HSP levels over time and their relationships with the clinical parameters of CKD in children. In total, 117 children with CKD and 56 healthy children were examined. The CKD group was followed up prospectively for 24 months. Serum and urine HSP27, HSP40, HSP47, HSP60, HSP70, HSP72, and HSP90 levels and serum anti-HSP60 and anti-HSP70 levels were measured by ELISA at baseline, 12 months, and 24 months. The urine levels of all HSPs and the serum levels of HSP40, HSP47, HSP60, HSP70, anti-HSP60, and anti-HSP70 were higher at baseline in the CKD group than in the control group. Over the months, serum HSP47 and HSP60 levels steadily decreased, whereas HSP90 and anti-HSP60 levels steadily increased. Urine HSP levels were elevated in children with CKD; however, with the exception of HSP90, they decreased over time. In conclusion, our study demonstrates that CKD progression is a complicated process that involves HSPs, but they do not predict CKD progression. The protective role of HSPs against CKD may weaken over time, and HSP90 may have a detrimental effect on the disease course.

Urine Levels of Matrix Metalloproteinases and Tissue Inhibitor of Metalloproteinases in Children with Type 1 Diabetes Mellitus

Objective: Histopathological changes in the kidney in type 1 diabetes mellitus (T1DM) begin before detection of microalbuminuria. Therefore, there is interest in finding a better biomarker for the early detection of diabetic kidney injury. The aim of this present study was to determine whether urinary indicators of fibrosis are detectable early in the development of T1DM in children and if they may predict progressive renal injury. Methods: Urinary matrix metalloproteinase 2 and 9 (MMP2 and MMP9), tissue inhibitor of metalloproteinase 1 and 2 (TIMP1 and TIMP2) and transforming growth factor-ß1 (TGF-ß1) were assessed in 33 patients with T1DM with normal renal functions and in 24 healthy controls. Microalbuminuria was not present in the patient group with the exception of three patients. The results were adjusted to urine creatinine (Cr) and the differences between patients and controls were evaluated. These measurements were repeated after one year and the results were compared with the first year results. Results: Urine MMP2/Cr, MMP9/Cr, TIMP1/Cr, TIMP2/Cr, TGF-ß1/Cr were not different between the patient and control groups (p>0.05). There were also no significant differences between the first and second year results for these biomarkers (p>0.05). None of these parameters were correlated with hemoglobin A1c, body mass index and duration of T1DM. Interestingly, all parameters were negatively correlated to age of onset of T1DM (p<0.05). Conclusion: Our findings suggest that urinary biomarkers of fibrosis do not show an increase in diabetic children without microalbuminuria. The results also indicate that the risk of early fibrosis may increase as age of onset of T1DM decreases.

Glomerular and Tubular Functions in Children and Adults with Transfusion-Dependent Thalassemia.

This study aimed at assessing renal functions in patients with transfusion-dependent thalassemia (TDT). Fifty patients and 30 controls were enrolled in this prospective study. Serum levels of electrolytes and albumin were measured by a spectrophotometer. Serum levels of cystatin-C and urinary levels of ß2-microglobulin were measured by nephelometric method. Thirty-eight patients were receiving deferasirox and 8 were on deferiprone. Serum electrolytes and albumin levels of the patients were found to be within normal ranges. Urinary ß2-microglobulin and serum cystatin-C levels were significantly higher in patients than controls. They did not significantly differ between the subgroup of patients on deferiprone and the control group, whereas they were found to be higher in patients using deferasirox compared to controls. Urinary ß2-microglobulin levels significantly increased in patients who were receiving high-dose deferasirox compared to those who were receiving a daily dose of 15-20 mg/kg or controls. Subclinical renal injury may be present in TDT patients.

Urine heat shock protein 70 levels as a marker of urinary tract infection in children.

BACKGROUND: Heat shock proteins (HSPs) are a multi-family group of proteins which are upregulated by the cell in response to exposure to hazardous (stress) factors, including infectious agents, to prevent changes in protein structure. The aim of our study was to assess whether urine levels of the 70-kDa family of HSPs (HSP70s) increase in children with urinary tract infection (UTI) and to determine the optimal urine (u) HSP70 cut-off level to predict UTI in children. METHODS: Forty patients with symptomatic UTI (UTI group), 30 healthy children (control group), 21 asymptomatic patients with proven bacterial contamination in their urine culture (contamination group) and 30 patients with fever caused by other infections (non-UTI infection group) were enrolled in the study. Random urine samples were obtained for measurement of HSP70 and creatinine (Cr) from all groups. Urine was collected prior to the treatment of UTI at the time of presentation and after treatment. Urine HSP70 levels were measured by enzyme-linked immunosorbent analysis. A dimercaptosuccinic acid (DMSA) scan was performed at 5-7 days after presentation in UTI group to distinguish patients with acute pyelonephritis from those with cystitis; based on this scan, no patients had acute pyelonephritis. Patients were classified with pyelonephritis in the presence of all of the following signs: axillary fever of ≥39 °C, leukocytosis and positivity for C-reactive protein. RESULTS: The mean urine HSP70:Cr ratio (uHSP70/Cr) prior to treatment was significantly higher in the UTI group (449.86 ± 194.33 pg/mg) than in the control, contamination and non-UTI infection groups (39.93 ± 47.61, 32.43 ± 9.09 and 45.14 ± 19.76, respectively; p = 0.0001). Using a cut-off of 158 pg/mg uHSP70/Cr for the prediction of UTI, the sensitivity and specificity of the assay were 100 and 100 %, respectively (area under the time-concentration curve = 1). The uHSP70/Cr was highest in the patients with clinical pyelonephritis (p = 0.001). Mean uHSP70/Cr after treatment decreased to 60.68 ± 51.11 pg/mg in UTI group (p = 0 .0001). CONCLUSIONS: Our findings suggest that elevated uHSP70/Cr may be a useful biomarker for the prediction of UTI in children, with a high sensitivity and specificity, and that they may help to distinguish UTI from other infections as well as bacterial contamination of the urine.

Higher urine heat shock protein 70/creatinine ratio in type 1 diabetes mellitus.

Insidious progressive renal damage caused by type 1 diabetes mellitus (T1DM) begins in childhood before it becomes manifest in adult ages. Heat shock proteins (HSPs) regulate the cell response to any hazardous factors to prevent cell structure. The aim of the study is to determine whether urine levels of HSPs increase in diabetic children with time and indicate a progressive renal injury in T1DM. Thirty-three patients with T1DM and 24 healthy children were enrolled in the study. Renal function was normal in all patients. Urine levels of HSP27, HSP40, HSP60, HSP70, and HSP90 were measured by enzyme-linked immunosorbent assay at two consecutive years (2012 and 2013). The results were evaluated as urine HSP/creatinine ratios (uHSP/Cr). Mean urine HSP27/Cr, HSP40/Cr, HSP60/Cr, HSP70/Cr, HSP90/Cr in patient group were significantly higher than in controls in 2012 (uHSP27/Cr 460.12 ± 217.64 versus 270.02 ± 136.83 pg/mgCr; uHSP40/Cr 180.89 ± 118.59 versus 99.44 ± 62.49 pg/mgCr; uHSP60/Cr 114.40 ± 64.91 versus 70.50 ± 43.70 pg/mgCr; uHSP70/Cr 41.17 ± 28.42 versus 16.47 ± 7.32 pg/mgCr; uHSP90/Cr 175.64 ± 102.22 versus 107.61 ± 75.85 pg/mgCr) (p < 0.05). In 2013, uHSP70/Cr level increased significantly (51.08 ± 27.72 pg/mgCr; p = 0.001), whereas uHSP60/Cr level decreased and uHSP27/Cr, uHSP40/Cr, uHSP90/Cr levels remained stable (p > 0.05). Area under the curve (AUC) for uHSP70/Cr (0.957) was significantly higher than the others. Using a cutoff 22.59 pg/mgCr for uHSP70/Cr to predict of diabetic damage, sensitivity and specificity were 85% and 96%, respectively. Our results suggest that uHSP70/Cr increases over time and may indicate early phases of progressive kidney damage in diabetic children.

ADCK4-Associated Glomerulopathy Causes Adolescence-Onset FSGS.

Hereditary defects of coenzyme Q10 biosynthesis cause steroid-resistant nephrotic syndrome (SRNS) as part of multiorgan involvement but may also contribute to isolated SRNS. Here, we report 26 patients from 12 families with recessive mutations in ADCK4. Mutation detection rate was 1.9% among 534 consecutively screened cases. Patients with ADCK4 mutations showed a largely renal-limited phenotype, with three subjects exhibiting occasional seizures, one subject exhibiting mild mental retardation, and one subject exhibiting retinitis pigmentosa. ADCK4 nephropathy presented during adolescence (median age, 14.1 years) with nephrotic-range proteinuria in 44% of patients and advanced CKD in 46% of patients at time of diagnosis. Renal biopsy specimens uniformly showed FSGS. Whereas 47% and 36% of patients with mutations in WT1 and NPHS2, respectively, progressed to ESRD before 10 years of age, ESRD occurred almost exclusively in the second decade of life in ADCK4 nephropathy. However, CKD progressed much faster during adolescence in ADCK4 than in WT1 and NPHS2 nephropathy, resulting in similar cumulative ESRD rates (>85% for each disorder) in the third decade of life. In conclusion, ADCK4-related glomerulopathy is an important novel differential diagnosis in adolescents with SRNS/FSGS and/or CKD of unknown origin.

An easily missed diagnosis: 17-alpha-hydroxylase/17,20-lyase deficiency.

The CYP17A1 gene encodes the enzyme P450c17, which mediates both 17α-hydroxylase and 17,20-lyase activities and is essential for production of cortisol and sex steroids. Loss-of-function mutations of this gene cause 17α-hydroxylase/17,20-lyase deficiency, characterized by hypertension, hypokalemia and sexual infantilism. A 6-year-old phenotypically female patient presented with hypertension and hyperpigmentation. Her blood test results showed low cortisol and high adrenocorticotropic hormone (ACTH), progesterone, deoxycorticosterone and gonadotropin levels and were consistent with the diagnosis of 17α-hydroxylase/17,20-lyase deficiency. Her karyotype was 46XY. Genetic studies of the patient revealed a novel homozygous point mutation, c.1307G>A, within the coding sequence of the CYP17A1 gene. 17α-hydroxylase/17,20-lyase deficiency should be considered in the differential diagnosis of hypertension in children and adolescents, and physical examination of these patients should be done very carefully.

Development of a medication adherence scale for familial Mediterranean fever (MASIF) in a cohort of Turkish children.

OBJECTIVES: To develop and assess the validity and reliability of an adherence scale concerning medical treatment in paediatric FMF patients. METHODS: The Medication Adherence Scale in FMF Patients (MASIF) is a 18-item questionnaire that evaluates adherence to medication in four domains. Validation of the instrument was accomplished in paediatric FMF patients (aged 2-18 years) under medication at least for 6 months. The first step was to build up the scale through qualitative approach (with interviews using semi-structured questions). Validation analyses included assessment of feasibility, face and content validity; construct validity, internal consistency and test-retest reliability. RESULTS: One hundred and fifty patients with FMF were enrolled in the study. The mean age of the patients was 11.11±4.02 years and 48.7% of them were male. The MASIF was found to be feasible and valid for both face and content. It correlated with the Morisky Medication Adherence Scale as a gold standard thereby demonstrating good construct validity (r=0.515, p<0.001). Assessment of content validity identified four subscales. The internal consistency, Cronbach's alpha was 0.728. There was a positive and significant correlation between test and retest scores (r=0.843; p<0.001). Also, a significant correlation between parents' and children's reports (r=0.781, p<0.001). CONCLUSIONS: Based on these results, the use of this scale to assess and follow up the adherence to treatment in paediatric FMF patients under medical treatment is recommended.

Pathogens causing urinary tract infections in infants: a European overview by the ESCAPE study group.

UNLABELLED: Knowledge of the distribution spectrum of causative organisms and their resistance patterns has become a core requirement for the rational and effective management of urinary tract infections. In the context of a prospective trial on the use of antibiotic prophylaxis in infants with underling kidney malformations, we conducted an online survey among paediatric nephrologists on positive urine cultures (July 2010-June 2012) from both hospitalized and non-hospitalized infants under 24 months of age. We collected 4745 urine cultures (UCs) at 18 units in 10 European countries. Escherichia coli was the most frequent bacterium isolated from UCs; however, in 10/16 hospitals and in 6/15 community settings, E. coli was isolated in less than 50% of the total positive UCs. Other bacterial strains were Klebsiella, Enterococcus, Proteus and Pseudomonas not only from hospital settings. E. coli showed a high resistance to amoxicillin and trimethoprim and variable to cephalosporin. Nitrofurantoin had a good rate of efficacy, with 11/16 hospitals and 11/14 community settings reporting a resistance lower than 5%. CONCLUSION: E. coli is the most common organism causing UTIs in infants; however, other bacterial strains are frequently isolated. As a result, antibiotic prophylaxis should be more elastic and adaptable over time in order to guarantee maximum efficacy.

Relationship between clinical findings and genetic mutations in patients with familial Mediterranean fever.

BACKGROUND: Familial Mediterranean fever (FMF) is one of the most frequent genetic diseases encountered in the Mediterranean region. We aimed to investigate the correlation between genetic mutations and the clinical findings in 562 patients with FMF. METHODS: In this retrospective cross-sectional study conducted with patients' files between 2006, and 2013, reverse hybridization assay for MEFV gene mutations was used and the 12 most frequent mutations were screened. Mutation types and clinical findings were compared with variance analysis. RESULTS: The mean age was 6.9 ± 3.4 years (range, 1.8-11.6 years). The most common symptom was fever (97.3%). Thirty-four of the patients (6.04%) were admitted with periodic fever only. Of these patients, M694V was the most common mutation type (73.5%). The percentage of the patients predominantly presenting with recurrent abdominal pain was 77.78% and the most frequent mutations were M694V and E148Q. The rate of arthritis and arthralgia was significantly higher in patients with M694V and E148Q mutations. Chest pain was reported more often in patients homozygous for M694V (61.4%). Pericardial effusion was documented in the echocardiography of 10.9% of the 229 children with chest pain. Some patients had both FMF and Henoch Schönlein purpura (HSP), and were more likely to harbor either homozygote M694V or E148Q mutations. The frequency of episodes was higher in patients with homozygous M694V mutations (number of attacks = 4.4 ± 1.6/month). Proteinuria was detected in 106 patients of cases (29.2%), at an average of 854 ± 145 mg/L. Most of the patients with proteinuria and elevated serum amyloid-A had homozygous M694V mutation. CONCLUSION: The most common mutation in children in Turkey with FMF is the M694V mutation. Recurrent abdominal pain, arthritis or arthralgia, chest pain, and pericarditis were commonly seen in patients with M694V and E148Q mutations.

Clinical importance of renal calyceal microlithiasis in children.

BACKGROUND: Renal calyceal microlithiasis refers to a hyperechogenic spot in renal calyces <3 mm in diameter detected on renal sonography. These spots possibly represent the first step in calculus formation. The aim of this study was to analyze the clinical presentation, predisposing factors, prognosis and clinical importance of these hyperechogenic spots in renal calyces, renal calyceal microlithiasis, during childhood. METHODS: The data of 292 children (135 girls, 157 boys) with microlithiasis diagnosed between January 1998 and December 2010 were evaluated retrospectively. Demographic data, serum biochemistry, urinary metabolic factors, and renal sonography results were obtained from patient files. A total of 228 patients were re-evaluated at least 6 months after the first observation of renal calyceal microlithiasis and at 6-12 month intervals thereafter. RESULTS: Mean age was 16.8 ± 14.9 months, and mean follow-up duration was 14.6 ± 5.9 months. Presenting symptoms were abdominal or flank pain (41.1%), hematuria (35.6%), dysuria (24.7%) and urinary tract infection (34.6%). Previous ultrasounds were normal in 35% of the children. Metabolic and anatomic abnormalities were found in 55.5% and 17.8%, respectively. Hypercalciuria was the most common metabolic abnormality (88.9%). Among 228 patients who had been re-evaluated, microlithiasis disappeared in 37.7%; decreased in number or size in 23.7%; progressed to renal stone formation in 10.6%; increased in number of microlithiasis in 19.0%; and remained unchanged on radiology in 9.0%. CONCLUSION: Renal calyceal microlithiasis represents a spectrum of clinical situations and underlying metabolic abnormalities that need further investigation in children.

Management of anemia in children receiving chronic peritoneal dialysis.

Little information exists regarding the efficacy, modifiers, and outcomes of anemia management in children with CKD or ESRD. We assessed practices, effectors, and outcomes of anemia management in 1394 pediatric patients undergoing peritoneal dialysis (PD) who were prospectively followed in 30 countries. We noted that 25% of patients had hemoglobin levels below target (<10 g/dl or <9.5 g/dl in children older or younger than 2 years, respectively), with significant regional variation; levels were highest in North America and Europe and lowest in Asia and Turkey. Low hemoglobin levels were associated with low urine output, low serum albumin, high parathyroid hormone, high ferritin, and the use of bioincompatible PD fluid. Erythropoiesis-stimulating agents (ESAs) were prescribed to 92% of patients, and neither the type of ESA nor the dosing interval appeared to affect efficacy. The weekly ESA dose inversely correlated with age when scaled to weight but did not correlate with age when normalized to body surface area. ESA sensitivity was positively associated with residual diuresis and serum albumin and inversely associated with serum parathyroid hormone and ferritin. The prevalence of hypertension and left ventricular hypertrophy increased with the degree of anemia. Patient survival was positively associated with achieved hemoglobin and serum albumin and was inversely associated with ESA dose. In conclusion, control of anemia in children receiving long-term PD varies by region. ESA requirements are independent of age when dose is scaled to body surface area, and ESA resistance is associated with inflammation, fluid retention, and hyperparathyroidism. Anemia and high ESA dose requirements independently predict mortality.

Genetic screening in adolescents with steroid-resistant nephrotic syndrome.

Genetic screening paradigms for congenital and infantile nephrotic syndrome are well established; however, screening in adolescents has received only minor attention. To help rectify this, we analyzed an unselected adolescent cohort of the international PodoNet registry to develop a rational screening approach based on 227 patients with nonsyndromic steroid-resistant nephrotic syndrome aged 10-20 years. Of these, 21% had a positive family history. Autosomal dominant cases were screened for WT1, TRPC6, ACTN4, and INF2 mutations. All other patients had the NPHS2 gene screened, and WT1 was tested in sporadic cases. In addition, 40 sporadic cases had the entire coding region of INF2 tested. Of the autosomal recessive and the sporadic cases, 13 and 6%, respectively, were found to have podocin-associated nephrotic syndrome, and 56% of them were compound heterozygous for the nonneutral p.R229Q polymorphism. Four percent of the sporadic and 10% of the autosomal dominant cases had a mutation in WT1. Pathogenic INF2 mutations were found in 20% of the dominant but none of the sporadic cases. In a large cohort of adolescents including both familial and sporadic disease, NPHS2 mutations explained about 7% and WT1 4% of cases, whereas INF2 proved relevant only in autosomal dominant familial disease. Thus, screening of the entire coding sequence of NPHS2 and exons 8-9 of WT1 appears to be the most rational and cost-effective screening approach in sporadic juvenile steroid-resistant nephrotic syndrome.

Comparison of recombinant human erythropoietin and darbepoetin alpha in children.

BACKGROUND: The aim was to compare the clinical efficacy of recombinant human erythropoietin (rHuEPO) and darbepoetin alpha (DA) in the treatment of anemia in children with chronic kidney disease (CKD). METHOD: Thirty-four (13 female, 21 male) CKD patients were enrolled in the study. Mean age was 11.42 ± 4.05 years. Nine patients were on hemodialysis, 18 were on peritoneal dialysis and seven patients were in CKD stage 4. RESULTS: Seventeen patients received rHuEPO and the remaining 17 patients received DA. Hemoglobin (Hb) was not significantly different between the two groups during monthly follow up and at the end of 6 months (P > 0.05), but there was a significant increase within each group at the end of 6 months (P = 0.01 for rHuEPO; P = 0.02 for DA). Hb was not different between the patients on and not on dialysis in both groups at the end of the study (P > 0.05). The efficacy of the s.c. and i.v. routes was similar within each group (P > 0.05). Systolic hypertension was observed in only one patient in the DA group, no other adverse effect was observed in either groups. CONCLUSION: DA is a reasonable alternative to rHuEPO in the treatment of anemia in pediatric CKD patients, due to its clinical efficacy, convenience of use, patient compliance and tolerability.

Circulating suPAR in two cohorts of primary FSGS.

Overexpression of soluble urokinase receptor (suPAR) causes pathology in animal models similar to primary FSGS, and one recent study demonstrated elevated levels of serum suPAR in patients with the disease. Here, we analyzed circulating suPAR levels in two cohorts of children and adults with biopsy-proven primary FSGS: 70 patients from the North America-based FSGS clinical trial (CT) and 94 patients from PodoNet, the Europe-based consortium studying steroid-resistant nephrotic syndrome. Circulating suPAR levels were elevated in 84.3% and 55.3% of patients with FSGS patients in the CT and PodoNet cohorts, respectively, compared with 6% of controls (P<0.0001); inflammation did not account for this difference. Multiple regression analysis suggested that lower suPAR levels associated with higher estimated GFR, male sex, and treatment with mycophenolate mofetil. In the CT cohort, there was a positive association between the relative reduction of suPAR after 26 weeks of treatment and reduction of proteinuria, with higher odds for complete remission (P=0.04). In the PodoNet cohort, patients with an NPHS2 mutation had higher suPAR levels than those without a mutation. In conclusion, suPAR levels are elevated in geographically and ethnically diverse patients with FSGS and do not reflect a nonspecific proinflammatory milieu. The associations between a change in circulating suPAR with different therapeutic regimens and with remission support the role of suPAR in the pathogenesis of FSGS.

Matrix metalloproteinase 9 and tissue inhibitor of metalloproteinase 1 in vesicoureteral reflux.

The aim of this study was to investigate whether urine levels of matrix metalloproteinase 9 (uMMP9) and tissue inhibitor of metalloproteinase 1 (uTIMP1) are novel biomarkers of vesicoureteral reflux (VUR) and to determine the optimal cut-off levels of these enzymes to predict VUR in children. The study group consisted of 67 children with VUR and 20 healthy children. Urine MMP9 and TIMP1 levels were measured by an enzyme-linked immunosorbent assay. Children with VUR had significantly higher uMMP9 (1,539.8 vs. 256.4 pg/mL; p = 0.0001) and uTIMP1 (182 vs. 32.6 pg/mL; p = 0.0001) levels than healthy children. For the prediction of VUR, the sensitivity of uMMP9 was 67%, with a specificity of 85% [cut-off value 1,054 pg/mL; area under the curve (AUC) 0.77], and the sensitivity of uTIMP1 was 74%, with a specificity of 65% (cut-off value 18.7 pg/mL; AUC 0.73). Both uMMP9 and uTIMP1 levels were significantly higher in patients with renal scar (uMMP9: 3,117.3 vs. 1,234.15 pg/mL; p = 0.0001; uTIMP1: 551.05 vs. 128.64 pg/mL; p = 0.0001). Urine MMP9 levels had a sensitivity of 81.2%, with a specificity of 85% to predict renal scar in the VUR group (cut-off 1,054 pg/mL; AUC 0.88). The sensitivity of uTIMP1 was 75%, with a specificity of 90% to predict renal scar (cut-off 243.7 pg/mL; AUC 0.82). Based on these results, we suggest that uTIMP1 may be a useful marker to predict renal scarring with a different cut-off value from VUR and a high specificity at this cut-off point. Although uMMP9 seemingly cannot distinguish renal scar from VUR, the simultaneous increase in the level of both markers may indicate ongoing renal injury due to VUR.