Urinary transforming growth factor-β1 in children with obstructive uropathy

Protein Biomarkers in Chronic Kidney Disease in Children-What Do We Know So Far?

Chronic kidney disease (CKD) in children is a major concern of medical care and public health as it is related to high morbidity and mortality due to progression to end-stage kidney disease (ESKD). It is essential to identify patients with a risk of developing CKD to implement therapeutic interventions. Unfortunately, conventional markers of CKD, such as serum creatinine, glomerular filtration rate (GFR) and proteinuria, have many limitations in serving as an early and specific diagnostic tool for this condition. Despite the above, they are still the most frequently utilized as we do not have better. Studies from the last decade identified multiple CKD blood and urine protein biomarkers but mostly assessed the adult population. This article outlines some recent achievements and new perspectives in finding a set of protein biomarkers that might improve our ability to prognose CKD progression in children, monitor the response to treatment, or even become a potential therapeutic target.

The Usefulness of Urinary Periostin, Cytokeratin-18, and Endoglin for Diagnosing Renal Fibrosis in Children with Congenital Obstructive Nephropathy

Congenital obstructive nephropathy (CON) leads to renal fibrosis and chronic kidney disease. The aim of the study was to investigate the predictive value of urinary endoglin, periostin, cytokeratin-18, and transforming growth factor-β1 (TGF-β1) for assessing the severity of renal fibrosis in 81 children with CON and 60 controls. Children were divided into three subgroups: severe, moderate scars, and borderline lesions based on 99mTc-ethylenedicysteine scintigraphy results. Periostin, periostin/Cr, and cytokeratin-18 levels were significantly higher in the study group compared to the controls. Children with severe scars had significantly higher urinary periostin/Cr levels than those with borderline lesions. In multivariate analysis, only periostin and cytokeratin-18 were independently related to the presence of severe and moderate scars, and periostin was independently related to borderline lesions. However, periostin did not differentiate advanced scars from borderline lesions. In ROC analysis, periostin and periostin/Cr demonstrated better diagnostic profiles for detection of advanced scars than TGF-β1 and cytokeratin-18 (AUC 0.849; 0.810 vs. 0.630; 0.611, respectively) and periostin for detecting borderline lesions than endoglin and periostin/Cr (AUC 0.777 vs. 0.661; 0.658, respectively). In conclusion, periostin seems to be a promising, non-invasive marker for assessing renal fibrosis in children with CON. CK-18 and TGF-β1 demonstrated low utility, and endoglin was not useful for diagnosing advanced scars.

HMGB-1 and TGFβ-1 highlight immuno-inflammatory and fibrotic processes before proteinuria onset in pediatric patients with Alport syndrome

INTRODUCTION

Alport syndrome (ALP) is a rare genetic condition characterized by progressive involvement of the basal membranes and renal dysfunction. The purpose of the study was to evaluate urinary (u) and serum (s) levels of tumor growth factor (TGF)-beta(β) and high mobility group box (HMGB)-1 in ALP patients with normal renal function, albuminuria and proteinuria.

METHODS

A prospective, single-center study was performed with a follow-up period of 12 months, enrolling 11 pediatric ALP patients and 10 healthy subjects (HS). Normal values of serum creatinine, albuminuria and proteinuria, as well as unaltered estimated glomerular filtration rate (eGFR) were required at enrollment.

RESULTS

ALP patients had significantly higher levels of serum and urinary HMGB1 compared to HS. The same trend was observed for TGF-β1, with higher values in ALP patients than in HS. HMGB1 and TGF-β1 correlated with each other and with markers of renal function and damage. Urinary biomarkers did not correlate with eGFR, whereas sHMGB1 and sTGF-β1 were negatively related to filtration rate (r: - 0.66; p = 0.02, r: - 0.96; p < 0.0001, respectively). Using proteinuria as a dependent variable in a multiple regression model, only the association with sTGF-β1 (β = 0.91, p < 0.0001) remained significant.

CONCLUSIONS

High levels of HMGB1 and TGF-β1 characterized ALP patients with normal renal function, highlighting the subclinical pro-fibrotic and inflammatory mechanisms triggered before the onset of proteinuria. Further studies are needed to evaluate the role of HMGB1 and TGFβ-1 in ALP patients.

Emerging biomarkers of chronic kidney disease in children

Chronic kidney disease (CKD) has become a significant public health concern, as it is associated with substantial morbidity. Prior research has evaluated multiple novel CKD biomarkers to supplement serum creatinine and proteinuria. The ultimate goal of this research is to find biomarkers that can be used to accurately predict CKD progression and to better time outpatient follow-up, and referral for transplant. Also, an optimal panel of biomarkers can augment the predictive value of proteinuria and serum creatinine by enriching patient enrollment in clinical trials. In this review, we discuss salient findings on 12 candidate plasma and urine biomarkers and their reported association with CKD. We explore the common pathways of CKD progression and the pathophysiologic processes of tubulointerstitial injury, inflammation, repair, and fibrosis that are potentially classified by specific biomarkers. We describe both pediatric and adult findings and highlight the paucity of pediatric research in CKD progression. It will be important for cohorts with longitudinal follow-up to evaluate these CKD biomarkers for potential use in pediatric clinical trials and routine CKD management.

Interleukin-10-1082A/G polymorphism is associated with renal parenchymal damage in congenital anomalies of the kidney and urinary tract

AIM

The aim of the study was to investigate whether the functional IL10-1082A/G polymorphism exert a role in congenital anomalies of the kidney and urinary tract (CAKUT) in children. Also, the serum IL-10 and its association with genotype and renal parenchymal damage in CAKUT were explored.

METHODS

In the current case-control study, 134 paediatric cases of CAKUT and 382 unrelated controls were included. The genotyping of IL10-1082A/G polymorphism was performed by amplification refractory mutation system-PCR and IL-10 serum level was determined by ELISA.

RESULTS

Although, the genotype and allelic frequencies of IL10-1082 A/G polymorphism in cases and controls were similar (χ²  = 0.459; P = 0.79 and χ²  = 0.426; P = 0.51, respectively), significant different genotype distribution between patients with or without parenchymal damage/reduction was observed (χ²  = 6.9; P = 0.032). The GG-genotype was more frequent in cases with renal parenchymal damage/reduction compared to patients with preserved parenchyma (22% vs. 9%; OR = 2.987; 95% CI = 0.979-9.468; P = 0.031). On the contrary, the heterozygous genotype was less frequent among cases with parenchymal damage/reduction compared to cases with preserved parenchyma (39% vs. 59%; OR = 0.453; 95% CI = 0.214-0.958; P = 0.024). Additionally, the serum IL-10 was significantly higher in CAKUT patients compared to age-sex-matched controls (median 11.98; IQR: 7.14-31.6 vs. 5.92; IQR: 4.68-14.8; P = 0.0057). Among carriers of GG-genotype significantly higher IL-10 level was detected in cases with parenchymal damage/reduction, than cases with preserved parenchyma (P = 0.028).

CONCLUSION

Our results suggested that the functional -1082A/G polymorphism in IL10 is associated with risk of renal parenchymal damage/reduction rather than genetic predisposition to CAKUT. Additionally, our study supposes that immunoregulatory cytokine IL-10 might have a significant role in CAKUT.

Biomarkers and echocardiography for evaluating the improvement of the ventricular diastolic function after surgical relief of hydronephrosis

The pathophysiology of cardio-renal syndrome (CRS) is complex. Hydronephrosis caused by urolithiasis may cause cytokine release and lead to cardiac dysfunction. The aim of this study was to evaluate cardiac function changes observed in patients who received double J placement using feasible biomarkers and echocardiography. This was a prospective, single-center study. Eighty-seven patients who presented with acute unilateral hydronephrosis and received ureteroscope stone manipulation were enrolled. Echocardiography and cytokines were measured on the day of the operation and 24 hours after the procedure. Changes before and after surgery were assessed by the paired t-test and Wilcoxon test. Correlation analyses between echocardiographic diastolic indices and cytokine levels were performed using Pearson’s correlation coefficients. Patients with hydronephrosis showed a higher left atrium volume index (LAVI), decreased E', and increased E/ E' ratio, which indicated diastolic dysfunction. Patients with hydronephrosis also exhibited decreased global strain rates during isovolumetric relaxation (SR_IVR) and E/ SR_IVR, which confirmed the diastolic dysfunction. Significant reductions in LAVI, increases in SR_IVR and decreases in E/ SR_IVR were observed after the operation. Biomarkers, such as TGF-β and serum NT-proBNP, were significantly decreased after surgery. In addition, a significant correlation was observed between the post-surgical decrease in TGF-β1 and increase in SR_IVR. Unilateral hydronephrosis causes cardiac diastolic dysfunction, and relieving hydronephrosis could improve diastolic function. Improvements in cardiac dysfunction can be evaluated by echocardiography and measuring cytokine levels. The results of this study will inform efforts to improve the early diagnosis of CRS and prevent further deterioration of cardiac function when treating patients with hydronephrosis.

Urine interleukin-6, interleukin-8 and transforming growth factor β1 in infants with urinary tract infection and asymptomatic bacteriuria

INTRODUCTION

Urinary tract infection (UTI) occurs in 1.1% of girls and 1.4% of boys during the first year of life. Asymptomatic bacteriuria (ABU) is usually detected incidentally in 0.9% of girls and 2.5% of boys at this age. The aim of the study was to assess the usefulness of measurement of pro-inflammatory urine interleukin (IL)-6 and IL-8 concentrations and anti-inflammatory transforming growth factor β1 (TGF-β1) level in infants with febrile UTI, non-febrile UTI and ABU.

MATERIAL AND METHODS

A total of 35 children, mean age 6.14 ±3.47 months, were divided into three groups: group I - febrile UTI (n = 13), group II - non-febrile UTI (n = 13) and group III - ABU (n = 9). At the time of enrollment urine IL-6, IL-8, TGF-β1 and serum C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and white blood cell count (WBC) were measured. Renal ultrasound was performed in all children, 99mTc-dimercaptosuccinic acid scintigraphy (DMSA) and voiding cystourethrography in children with UTI.

RESULTS

Urine concentrations of IL-6 and IL-8 were significantly higher in febrile UTI compared to those with non-febrile UTI and ABU (p < 0.5, p < 0.01) and positively correlated with CRP, ESR and WBC (p < 0.01). Urine levels of TGF-β1 were significantly higher in children with febrile UTI compared to those with ABU (p < 0.05) and positively correlated with WBC (p < 0.01). Inflammatory changes in the DMSA scan were detected in 66.6% of children with UTI. No significant difference in frequency of an abnormal DMSA scan compared to a normal scan was found in groups with febrile and non-febrile UTI. No relations between urine cytokines, systemic inflammatory markers and changes in DMSA scan were observed. The cutoff value for detection of inflammatory changes in the DMSA scan for IL-8 was 120 pg/mg creatinine (Cr) and 40 pg/mg Cr for TGF-β1. Based on this value, the sensitivity for IL-8 was 58.3%, specificity 100% and for TGF-β1 66.7% and 83.7%, respectively.

CONCLUSIONS

We found significant differences in children with febrile UTI and ABU regarding urine IL-6, IL-8 and TGF-β1 levels. Urine cytokines and systemic inflammatory markers do not differentiate between upper and lower UTI in infants.

Urine exoglycosidases are potential markers of renal tubular injury in children with ureteropelvic junction obstruction

AIM

Hydronephrosis caused by ureteropelvic junction obstruction (UPJO) is an important problem in children and young adults. The aim of this pilot study was to determine the urine profiles of a number of lysosomal exoglycosidases to see whether they indicated tubular renal damage in children with UPJO.

METHODS

We measured lysosomal exoglycosidases urine activities in 32 patients with UPJO, dividing them into three groups. The surgical group comprised 16 children with severe hydronephrosis who required surgery, the nonsurgical group comprised 16 patients with mild hydronephrosis, and the reference group comprised 42 healthy children. The following indicators were measured: N-acetyl-β-hexosaminidase and its A and B isoenzymes, α-fucosidase, β-galactosidase, α-mannosidase and β-glucuronidase.

RESULTS

The urine activities of all exoglycosidases were significantly higher in children with UPJO than children in the reference group (p < 0.01). A strong positive correlation was also found between most of the urine exoglycosidases and the urine albumin/creatinine ratio (p < 0.01).

CONCLUSION

Our findings demonstrated that children with UPJO showed increased renal activities of assessed exoglycosidases, which correlated positively with the urine albumin/creatinine ratio. A larger multicentre study is required to confirm the clinical applications of these observations.

Tumor suppressor ataxia telangiectasia mutated functions downstream of TGF-β1 in orchestrating profibrotic responses

Effective therapy to prevent organ fibrosis, which is associated with more than half of all mortalities, remains elusive. Involvement of tumor suppressor ataxia telangiectasia mutated (ATM) in the TGF-β1 pathway related to renal fibrosis is largely unknown. ATM activation (pATM(Ser1981)) increased 4-fold in the tubulointerstitial region of the unilateral ureteral obstruction-injured kidney in mice correlating with SMAD3 and p53(Ser15) phosphorylation and elevated levels of p22(phox) subunit of the NADPH oxidases (NOXs), and fibrotic markers, plasminogen activator inhibitor-1 (PAI-1), and fibronectin, when compared to contralateral (contra) or sham controls. In fact, ATM is rapidly phosphorylated at Ser(1981) by TGF-β1 stimulation. Stable silencing and pharmacologic inhibition of ATM ablated TGF-β1-induced p53 activation (>95%) and subsequent PAI-1, fibronectin, connective tissue growth factor, and p21 expression in human kidney 2 (HK-2) tubular epithelial cells and normal rat kidney-49 fibroblasts (NRK-49F). ATM or p53 depletion in HK-2 cells, moreover, bypassed TGF-β1-mediated cytostasis evident in control short hairpin RNA-expressing HK-2 cells. Interestingly, stable silencing of NOX subunits, p22(phox) and p47(phox), in HK-2 cells blocked TGF-β1-induced pATM(Ser1981) (>90%) and target gene induction via p53-dependent mechanisms. Furthermore, NRK-49F fibroblast proliferation triggered by conditioned media from TGF-β1-stimulated, control vector-transfected HK-2 cells decreased (∼ 50%) when exposed to conditioned media from ATM-deficient, TGF-β1-treated HK-2 cells. Thus, TGF-β1 promotes NOX-dependent ATM activation leading to p53-mediated fibrotic gene reprogramming and growth arrest in HK-2 cells. Furthermore, TGF-β1/ATM-initiated paracrine factor secretion by dysfunctional renal epithelium promotes interstitial fibroblast growth, suggesting a role of tubular ATM in mediating epithelial-mesenchymal cross-talk highlighting the translational benefit of targeting the NOX/ATM/p53 axis in renal fibrosis.

Evaluation of urinary biomarkers for the prognosis of drug-associated chronic tubulointerstitial nephritis

BACKGROUND

The efficacy of urinary biomarkers for predicting adverse clinical outcomes in drug-induced chronic tubulointerstitial nephritis (D-CTIN) has not been well described.

METHODS

A total of 54 patients with D-CTIN were prospectively followed-up in this study. The urinary excretion of α1-microglobulin and transforming growth factor-β1 and the activity of urinary N-acetyl-β-D-glucosaminidase (NAG) and matrix metalloproteinases (MMPs) 2 and 9 at baseline were measured. Changes in the estimated glomerular filtration rate (GFR) over a period of 11 to 54 months (median, 38 months) of follow-up were recorded. The efficacy of urinary biomarkers for differentiating patients with various outcomes was tested. Ten patients with IgA nephropathy and 20 healthy volunteers were enrolled as controls.

RESULTS

The areas under the receiver operating characteristic curve for urinary NAG, MMP-9, MMP-2 and α1-microglobulin for predicting deterioration of the estimated GFR were 0.879, 0.867, 0.735 and 0.709, respectively (P < 0.05 for all). Partial regression coefficient results demonstrated that urinary NAG (P = 0.02), MMP-2 (P = 0.046) and MMP-9 (P = 0.041) were inversely correlated with the rate of GFR decline.

CONCLUSIONS

Urinary NAG, MMP-2 and MMP-9 may be considered as possible candidates for forecasting the progression rate of D-CTIN.

Interactions between cytokines, congenital anomalies of kidney and urinary tract and chronic kidney disease

Fetal hydronephrosis is the most common anomaly detected on antenatal ultrasound, affecting 1-5% of pregnancies. Postnatal investigation has the major aim in detecting infants with severe urinary tract obstruction and clinically significant urinary tract anomalies among the heterogeneous universe of patients. Congenital uropathies are frequent causes of pediatric chronic kidney disease (CKD). Imaging techniques clearly contribute to this purpose; however, sometimes, these exams are invasive, very expensive, and not sufficient to precisely define the best approach as well as the prognosis. Recently, biomarkers have become a focus of clinical research as potentially useful diagnostic tools in pediatric urological diseases. In this regard, recent studies suggest a role for cytokines and chemokines in the pathophysiology of CAKUT and for the progression to CKD. Some authors proposed that the evaluation of these inflammatory mediators might help the management of postnatal uropathies and the detection of patients with high risk to developed chronic kidney disease. Therefore, the aim of this paper is to revise general aspects of cytokines and the link between cytokines, CAKUT, and CKD by including experimental and clinical evidence.

Less expression of prohibitin is associated with increased caspase-3 expression and cell apoptosis in renal interstitial fibrosis rats

AIMS

Prohibitin (PHB), a ubiquitous protein, is involved in a variety of molecular functions. Renal interstitial fibrosis (RIF) is a hallmark of common progressive chronic diseases that lead to renal failure. This study was performed to investigate whether PHB was associated with caspase-3 expression/cell apoptosis in RIF rats.

METHODS

Twenty-four male Wistar rats were randomly divided into two groups: sham operation group (SHO) and model group subjected to unilateral ureteral obstruction (GU), n = 12, respectively. The model was established by left ureteral ligation. Renal tissues were collected at 14 days and 28 days after surgery. RIF index, cell apoptosis index, protein expression of PHB, transforming growth factor-βl (TGF-β1), collagen-IV (Col-IV), fibronectin (FN) or caspase-3 in renal interstitium, and mRNA expression of PHB in renal tissue were detected.

RESULTS

Compared with that in the SHO group, the PHB expression (mRNA and protein) was significantly reduced (P < 0.01). Protein expressions of TGF-β1, Col-IV, FN and caspase-3, and RIF index or cell apoptosis index in GU group were markedly elevated compared with those in SHO group (all P < 0.01). The protein expression of PHB had a negative correlation with the protein expression of TGF-β1, Col-IV, FN or caspase-3, and RIF index or cell apoptosis index (each P < 0.01).

CONCLUSIONS

Less expression of PHB is associated with increased caspase-3 expression/cell apoptosis in RIF rats. However, further research is needed to determine the effect of PHB on caspase-3 expression/cell apoptosis and to determine the potential of PHB as a therapeutic target.