Renal expression of monocyte chemotactic protein-1 and epidermal growth factor in children with obstructive hydronephrosis

A systematic review of underlying genetic factors associated with ureteropelvic junction obstruction in stenotic human tissue

OBJECTIVE

Genetic factors are implicated in the development of ureteropelvic junction obstruction (UPJO). The aims of this study were: 1) condense and examine the existing data in studies containing information regarding differential gene expression in tissues from patients with UPJO and 2) investigate associations between genetic markers and their related pathways.

MATERIALS AND METHODS

A systematic review of studies published between January 2000 and September 2021 was conducted using the following databases: Ovid/Medline, PubMed, Wiley Cochrane Central Register of Controlled Trials, Web of Science, and Scopus. Of 249 studies, 10 were included in the final analysis. The search was performed using the terms "ureteropelvic junction obstruction", "genetic", "gene", and "gene expression". Literature pertaining to differential gene expression in UPJO patients as compared to healthy controls was identified. Studies containing gene expression and quantification of molecular data carried out directly on stenotic tissue samples were selected for analysis. Gene network connections and functional analyses were then determined using MetaScape software.

RESULTS

From the ten studies identified for analysis, fifteen genes were noted as differentially expressed. In UPJO patients, nine genes were upregulated (ET1, ACTA2, MCP-1, TGFB1, NFKB1, IL-6, HIF1A, S100A1, SYP) and six were downregulated (ADM, NOS2, EGF, PDGFRA, UCHL1, NGFR). These genes were principally involved in HIF-1 signaling pathway, blood vessel development, positive regulation of signaling receptor activity, and Ras signaling pathway.

CONCLUSIONS

A potential link exists between genes related to hypoxia, excessive fibrous tissue formation, and inflammation in the development of UPJO, and these connections merit more detailed, tissue level investigations in UPJO patients. The outcomes of this systematic review may lay the groundwork for the development of future targeted therapies and novel biomarker detection for treatments, early detection, and possible prediction and prevention of development of UPJO.

CDH12 as a Candidate Gene for Kidney Injury in Posterior Urethral Valve Cases: A Genome-wide Association Study Among Patients with Obstructive Uropathies

Background

Posterior urethral valves (PUVs) and ureteropelvic junction obstruction (UPJO) are congenital obstructive uropathies that may impair kidney development.

Objective

To identify genetic variants associated with kidney injury in patients with obstructive uropathy.

Design, setting, and participants

We included 487 patients born in 1981 or later who underwent pyeloplasty or valve resection before 18 yr of age in the discovery phase, 102 PUV patients in a first replication phase, and 102 in a second replication phase.

Outcome measurements and statistical analysis

Signs of kidney injury were defined as dialysis, nephrectomy, kidney transplantation, estimated glomerular filtration rate (eGFR) <60 ml/min/1.73 m², high blood pressure, antihypertensive medication use, proteinuria, and/or one kidney functioning at <45%. We used χ² tests to calculate p values and odds ratios for >600 000 single-nucleotide polymorphisms (SNPs) in the discovery sample comparing patients with and without signs of kidney injury within 5 yr after surgery. We performed stratified analyses for PUV and UPJO and Kaplan-Meier and Cox regression analyses in the discovery and two replication samples for the associated SNPs, and RNA and protein expression analyses for the associated gene in fetal tissues.

Results and limitations

Despite the small and nonhomogeneous sample, we observed suggestive associations for six SNPs in three loci, of which rs6874819 in the CDH12 gene was the most clear (p = 7.5 × 10^–7). This SNP also seemed to be associated with time to kidney injury in the PUV discovery and replication samples. RNA expression analyses showed clear CDH12 expression in fetal kidneys, which was confirmed by protein immunolocalization.

Conclusions

This study identified CDH12 as a candidate gene for kidney injury in PUV.

Patient summary

We found that variants of the CDH12 gene increase the risk of kidney injury in patients with extra flaps of tissue in the urethra (posterior urethral valves). This is the first report on this gene in this context. Our study provides interesting new information about the pathways involved and important leads for further research for this condition.

Biomarkers in vesicoureteral reflux: an overview

Aim: This article aimed to review the role of cytokines, chemokines, growth factors and cellular adhesion molecules as biomarkers for vesicoureteral reflux (VUR) and reflux nephropathy (RN). Methods: We reviewed articles from 1979 onward by searching PubMed and Scopus utilizing the combination of words: 'VUR' or 'RN' and each one of the biomarkers. Results: Genetic, inflammatory, fibrogenic, environmental and epigenetic factors responsible for renal scarring need to be better understood. TGF-β, IL-10, IL-6, IL-8 and TNF seem to exert a role in VUR particularly in RN based on the current literature. Serum levels of procalcitonin have been also associated with high-grade VUR and RN. These molecules should be more intensively evaluated as potential biomarkers for renal scarring in VUR. Conclusion: Further studies are necessary to define which molecules will really be of utility in clinical decisions and as therapeutic targets for VUR and RN.

The molecular biology of pelvi-ureteric junction obstruction

Over recent years routine ultrasound scanning has identified increasing numbers of neonates as having hydronephrosis and pelvi-ureteric junction obstruction (PUJO). This patient group presents a diagnostic and management challenge for paediatric nephrologists and urologists. In this review we consider the known molecular mechanisms underpinning PUJO and review the potential of utilising this information to develop novel therapeutics and diagnostic biomarkers to improve the care of children with this disorder.

Emerging urinary markers of renal injury in obstructive nephropathy

The effects of obstruction on renal function are the consequence of many factors that profoundly alter all components of glomerular function. Besides the acute effects on glomerular filtration rate and tubule function, a chronic obstruction induces tubular and interstitial injury that results from the activation of different pathways. The progression of tubulointerstitial injury leads to chronic renal damage characterized by tubular atrophy, inflammatory cell infiltration, and interstitial fibrosis. Obstructive nephropathy is an evolving disease in which the renal damage continues even after relief of the obstruction. In particular, it has been demonstrated that the time of relief is the most important factor in predicting long-term renal function deterioration. In this setting, the EGF/MCP-1 ratio, urinary NGAL, and urinary KIM-1 are useful early biomarkers of progressive renal damage and could have a potential role in predicting the long-term renal outcome. This minireview summarizes the role of these emerging urinary biomarkers of obstructive nephropathy based on the current understanding of the pathophysiology of renal injury.

Emerging biomarkers and metabolomics for assessing toxic nephropathy and acute kidney injury (AKI) in neonatology

Identification of novel drug-induced toxic nephropathy and acute kidney injury (AKI) biomarkers has been designated as a top priority by the American Society of Nephrology. Increasing knowledge in the science of biology and medicine is leading to the discovery of still more new biomarkers and of their roles in molecular pathways triggered by physiological and pathological conditions. Concomitantly, the development of the so-called "omics" allows the progressive clinical utilization of a multitude of information, from those related to the human genome (genomics) and proteome (proteomics), including the emerging epigenomics, to those related to metabolites (metabolomics). In preterm newborns, one of the most important factors causing the pathogenesis and the progression of AKI is the interaction between the individual genetic code, the environment, the gestational age, and the disease. By analyzing a small urine sample, metabolomics allows to identify instantly any change in phenotype, including changes due to genetic modifications. The role of liquid chromatography-mass spectrometry (LC-MS), proton nuclear magnetic resonance (1H NMR), and other emerging technologies is strategic, contributing basically to the sudden development of new biochemical and molecular tests. Urine neutrophil gelatinase-associated lipocalin (uNGAL) and kidney injury molecule-1 (KIM-1) are closely correlated with the severity of kidney injury, representing noninvasive sensitive surrogate biomarkers for diagnosing, monitoring, and quantifying kidney damage. To become routine tests, uNGAL and KIM-1 should be carefully tested in multicenter clinical trials and should be measured in biological fluids by robust, standardized analytical methods.

Chemokines as potential markers in pediatric renal diseases

Glomerular diseases and obstructive uropathies are the two most frequent causes of chronic kidney disease (CKD) in children. Recently, biomarkers have become a focus of clinical research as potentially useful diagnostic tools in pediatric renal diseases. Among several putative biomarkers, chemokines emerge as promising molecules since they play relevant roles in the pathophysiology of pediatric renal diseases. The evaluation of these inflammatory mediators might help in the management of diverse renal diseases in children and the detection of patients at high risk to develop CKD. The aim of this paper is to revise general aspects of chemokines and the potential link between chemokines and the most common pediatric renal diseases by including experimental and clinical evidence.

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.

Prediction of the outcome of antenatal hydronephrosis: significance of urinary EGF

BACKGROUND

Down-regulation of epidermal growth factor (EGF) in the renal parenchyma has been demonstrated in children who underwent pyeloplasty due to ureteropelvic junction obstruction (UPJO). Urine levels of EGF were confirmed to parallel this finding before and after surgery. The aim of our study was to evaluate the relationship between urinary EGF (uEGF) concentrations and Society of Fetal Urology (SFU) high-grade hydronephrosis in infants presenting unilateral antenatal hydronephrosis (ANH).

METHODS

This was a prospective study involving 45 infants (33 in the observational group, 12 in the surgical group) who presented with unilateral ANH. Postnatal evaluation included a clinical examination, renal ultrasonography, and voiding cystourethrography. Diuretic renal scans were performed in infants with an initial SFU grade 3 or 4 hydronephrosis or increasing hydronephrosis during follow-up. Pyeloplasty was performed when a well-tempered renogram showed an obstructive drainage curve with a half-life of >20 min and/or an obstructive washout curve pattern during the diuretic phase. We studied the longitudinal changes in SFU hydronephrosis grade and uEGF in each group and compared concentration levels at three time points in both groups. The enzyme-linked immunosorbent assay (ELISA) method was used to measure EGF concentrations in the urine. The results were normalized with urinary creatinine (Cr).

RESULTS

During the first 6 months, from 6 to 12 months, and in the second year of life, median SFU hydronephrosis grade and uEGF levels were 2, 2 (p = 0.015), and 1 (p < 0.01), and 50, 59 (p = 0.015), and 69.5 ng/mg Cr (p < 0.01), respectively, in the observational group. In the first 6 months, preoperatively and at 3-12 months postoperatively, the median SFU hydronephrosis grade and uEGF levels were 4, 4, and 3 (p > 0.05), and 38, 46, (p > 0.05), and 55 ng/mg Cr (p < 0.01), respectively, in the surgical group. uEGF levels in the first 6 months of life were significantly lower in the surgical group than in the observational group (p < 0.01). Patients in the observational group with SFU grade 3-4 hydronephrosis showed higher uEGF levels than those in the surgical group with SFU grade 3-4 in (p = 0.048).

CONCLUSIONS

Urinary EGF changes over time are associated with inverse changes in SFU hydronephrosis grade, which suggests a role for uEGF as a predictive marker of worsening hydronephrosis grades in infants with ANH. uEGF in the first 6 months of life may predict the need for surgery in infants with ANH.

Urinary NGAL, cystatin C, β2-microglobulin, and osteopontin significance in hydronephrotic children

BACKGROUND

Ureteropelvic junction obstruction (UPJO) accounts for 35 % of all congenital hydronephrosis cases. The challenge in managing childhood hydronephrosis is to distinguish obstructive from nonobstructive cases and, thereby, identify patients requiring surgical intervention. This study aimed to examine four urinary proteins as potential biomarkers of obstruction in hydronephrosis.

METHODS

Urine samples from 24 children with UPJO were collected pre-, peri-, and postoperatively, together with urine samples from healthy children. Neutrophil gelatinase-associated lipocalin (NGAL), cystatin C (CyC), β2-microglobulin (β2-M), and osteopontin (OPN) in the samples were measured simultaneously using multiplex sandwich immunoassay technology.

RESULTS

Compared with controls, NGAL and β2-M were significantly increased in urine from patients with obstructed kidneys at the time of surgery. This increase was followed by a decrease and stabilization to the same level as that of the controls. Furthermore, age was negatively correlated with preoperative urinary concentrations of CyC, β2-M, and OPN.

CONCLUSIONS

This study confirms increased concentrations of NGAL and β2-M in urine from obstructed kidneys and should be tested in larger studies to ascertain their ability to identify obstruction and to determine the importance of age-adjusted reference values.

Role of urinary biomarkers in the diagnosis of congenital upper urinary tract obstruction

Background:

Congenital obstructive uropathy constitutes a significant cause of morbidity in children. Currently, there is no reference standard for the diagnosis of renal obstruction in children. The noninvasive measurement of biomarkers in voided urine has considerable appeal as a potential application in children with congenital obstructive nephropathy. The aim of the present review is to explore the current role of biomarkers in the diagnosis and follow-up of obstructive uropathy in children.

Materials and Methods:

The literature database (PubMed) was searched from inception to May 2007 regarding the role of urinary biomarkers in the diagnosis and follow-up of children with congenital obstructive uropathy.

Results:

The review included 23 experimental and 33 prospective controlled clinical studies. Several cytokines, peptides, enzymes and microproteins were identified as major contributors to or ensuing from obstruction-induced renal fibrosis and apoptosis. The most important biomarkers were transforming growth factor-β₁ (TGFβ₁), epidermal growth factor (EGF), endothelin-1 (ET-1), urinary tubular enzymes [N-acetyl-β-D-glucosaminidase (NAG), γ-glutamyl transferase (GGT) and alkaline phosphatase (ALP)], and microproteins [β₂-microglobulin (β₂M), microalbumin (M. Alb) and micrototal protein (M.TP)]. All biomarkers showed different degrees of success but the most promising markers were TGFβ₁, ET-1 and a panel of tubular enzymes. These biomarkers showed sensitivity of 74.3% to 100%, specificity of 80% to 90% and overall accuracy of 81.5% to 94% in the diagnosis of congenital obstructive uropathy in children. Moreover, some of the markers were valuable in differentiation between dilated non-obstructed kidneys in need of conservative management and obstructed kidneys in need of surgical correction. Some studies demonstrated that urinary biomarkers are helpful in the evaluation of success of treatment of children with congenital renal obstruction. Some limitations of the previous studies include lack of different types of controls and small sample size. Larger studies with variable controls are invited to confirm the clinical usefulness of biomarkers in the diagnosis and follow-up of children with congenital obstructive uropathy.

Conclusion:

Urinary biomarkers are a promising tool that could be used as a noninvasive assessment of congenital renal obstruction in children.

Urinary biomarkers in prenatally diagnosed unilateral hydronephrosis

The introduction of prenatal ultrasonography as a screening method entails an increasing number of infants diagnosed with prenatal hydronephrosis. Ureteropelvic junction obstruction accounts for 35% of prenatal hydronephrotic cases. Urinary tract obstruction that occurs during early kidney development affects renal morphogenesis, maturation and growth, and in the most severe cases this will ultimately cause renal insufficiency. A major challenge in the clinical management of these patients is to preserve renal function by selection of the 15%-20% who require early surgical intervention, leaving those for whom watchful waiting may be appropriate because of spontaneous resolution/stabilization without significant loss of renal function. Today, this requires medical surveillance, including repetitive invasive diuretic renograms relying on arbitrary threshold values, and therefore there is a need for non-arbitrary, non-invasive urinary biomarkers that may be used as predictors for renal structural changes and/or decreasing renal function, and thereby provide the surgeon with more clear indications for surgical intervention. In this review, we summarize the currently well-known facts about urinary biomarkers in ureteropelvic junction obstruction concerning renal function, and we also suggest potential novel urinary biomarkers.

Urinary epidermal growth factor, monocyte chemotactic protein-1, and β2-microglobulin in children with ureteropelvic junction obstruction

BACKGROUND/PURPOSE

We demonstrated down-regulation of epidermal growth factor (EGF) and up-regulation of monocyte chemotactic protein-1 (MCP-1) in the renal parenchyma in children who underwent pyeloplasty for ureteropelvic junction obstruction (UPJO). These findings were paralleled by urinary levels of EGF and MCP-1 before and after surgery. The aim of this study is to evaluate the urinary excretion of these cytokines and β2-microglobulin (β2M) in children with urine flow impairment at the ureteropelvic junction or who underwent pyeloplasty.

METHODS

Seventy-six patients with UPJO and 30 normal children (CTRL) were enrolled in the study. The UPJO patients were divided into obstructive (12), functional (36), and operated (28). Epidermal growth factor, MCP-1, and β2M urinary levels were measured by enzyme-linked immunosorbent assay and normalized to urine creatinine.

RESULTS

Urinary β2M and MCP-1 increased significantly in the UPJO groups compared with the CTRL and significantly improved in the operated group. The obstructive group displayed reduced EGF excretion compared with the CTRL group. The urinary (u)EGF/uMCP-1, and uEGF/uβ2M ratios significantly decreased in both untreated groups. In the operated group, these ratios improved significantly.

CONCLUSIONS

The present study substantiates the role of urinary EGF, MCP-1, and β2M as markers of tubulointerstitial damage in human obstructive nephropathy. Furthermore, it suggests that surgical intervention is effective in the management of children with UPJO.

Obstructive renal injury: from fluid mechanics to molecular cell biology

Urinary tract obstruction is a frequent cause of renal impairment. The physiopathology of obstructive nephropathy has long been viewed as a mere mechanical problem. However, recent advances in cell and systems biology have disclosed a complex physiopathology involving a high number of molecular mediators of injury that lead to cellular processes of apoptotic cell death, cell injury leading to inflammation and resultant fibrosis. Functional studies in animal models of ureteral obstruction using a variety of techniques that include genetically modified animals have disclosed an important role for the renin-angiotensin system, transforming growth factor-β1 (TGF-β1) and other mediators of inflammation in this process. In addition, high throughput techniques such as proteomics and transcriptomics have identified potential biomarkers that may guide clinical decision-making.

[Prognostic markers for congenital hydronephroses]

Watchful waiting has become the standard therapy in most cases of asymptomatic unilateral congenital hydronephroses with normal renal function. Simple, reliable, and noninvasive prognostic parameters that predict an increased risk of functional deterioration either at the initial evaluation or during follow-up would be most useful. At the moment the diameter of the renal pelvis and especially its increase is the most useful prognostic parameter, while an "obstructed" washout at furosemide isotope renography is of limited prognostic value. Preclinical and preliminary clinical studies indicate that the measurement of molecules in the urine of affected children such as TGF-31 and MCP-1 that are involved in the signal transduction during hydronephrotic atrophy might become well accepted as useful prognostic parameters in the near future.

Complete Unilateral Ureteral Obstruction in the Fetal Lamb. Part II: Long-Term Outcomes of Renal Tissue Development

PURPOSE

We analyzed the dynamics of the renal tissue response to experimental fetal urinary flow impairment concerning renal morphology, extracellular matrix composition, regulators of connective tissue degradation and PAX2 protein expression.

MATERIALS AND METHODS

A total of 26 fetal lambs underwent surgical unilateral ureteral obstruction at 90 days of gestation and 14 twin matched animals served as controls. Kidneys were harvested 10, 20 and 40 days after the prior procedure in groups 1 to 3, respectively and in 1-month-old lambs (group 4). Morphological analysis was done using light microscopy. Picrosirius red staining was used to evaluate the area occupied by extracellular matrix components. Collagen I, III and IV, alpha-smooth muscle actin, MMP-1, 2 and 9, TIMP-1 and 2 and PAX2 protein were assessed using immunochemistry.

RESULTS

All obstructed kidneys were hydronephrotic without dysplasia. Hypoplasia resulting from a decreased NGG was observed. The inflammatory response to obstruction was poor in fetal obstructed kidneys. From 10 days after obstruction interstitial fibrosis was noted and confirmed by an increase in picrosirius red staining. In obstructed kidneys immunochemistry showed an increase in collagen deposition beginning from the papillae and extending through the whole parenchyma. Aberrant interstitial collagen IV deposition was observed. The increase in alpha-smooth muscle actin staining was mainly localized in the blastema and interstitial cells in obstructed kidneys. MMP and TIMP immunostaining was mainly present in tubules throughout the whole nephrogenic period and persisted in mature kidneys. Beginning from 20 days after obstruction a progressive increase in MMP and TIMP expression was noted. This was associated with ectopic expression in the medullary tubules. PAX2 protein was highly expressed in the nephrogenic zone, decreasing progressively to being markedly decreased in control lamb kidneys. No difference was found in PAX2 expression during the fetal period when comparing unobstructed and obstructed kidneys, it but remained strongly expressed in the dilated collecting ducts of obstructed lambs.

CONCLUSIONS

Complete unilateral ureteral obstruction performed in fetal lambs at 90 days of gestation led to pure hydronephrotic transformation, hypoplasia and a marked increase in connective tissue deposition. Inflammatory infiltrates and PAX2 dysregulation were not seen as having a decisive role in these modifications.

Renal expression of epidermal growth factor and transforming growth factor-beta1 in children with congenital hydronephrosis

OBJECTIVES

To study the potential role of pelviureteral junction obstruction (PUJO) in causing progressive renal damage in children through the renal expression of epidermal growth factor (EGF) and transforming growth factor-beta1 (TGF-beta1).

METHODS

The expression of EGF and TGF-beta1 was evaluated in the renal tissues of 25 children with congenital hydronephrosis by immunohistochemistry, in situ hybridization, and reverse transcriptase polymerase chain reaction techniques.

RESULTS

Children with PUJO had a significant increase in TGF-beta1 and a marked reduction in EGF expression compared with controls. The TGF-beta1/glyceraldehyde phosphate dehydrogenase ratio in the hydronephrotic kidney and normal kidney was 0.53 +/- 0.13 and 0.24 +/- 0.10 respectively, and the difference was significant (P = 0.000). The EGF/glyceraldehyde phosphate dehydrogenase ratio in the hydronephrotic kidney and normal kidney was 0.15 +/- 0.06 and 0.55 +/- 0.13, respectively, and the difference was also significant (P = 0.0001). Positive correlations were found between the TGF-beta1 gene and the drainage clearance half-time (r = 0.47; P = 0.018), TGF-beta1 protein and drainage clearance half-time (r = 0.44; P = 0.028), TGF-beta1 gene and histologic grade (r = 0.53; P = 0.006), and TGF-beta1 protein and histologic grade (r = 0.76; P = 0.000). Negative correlations were found between the EGF gene and drainage clearance half-time (r = -0.59; P = 0.002), EGF protein and drainage clearance half-time (r = -0.61; P = 0.001), EGF gene and histologic grade (r = -0.58; P = 0.003), and EGF protein and histologic grade (r = -0.47; P = 0.019).

CONCLUSIONS

TGF-beta1 expression was increased and EGF expression was decreased in the renal tissue after clinical PUJO. The alterations of TGF-beta1 and EGF may play a potential role in the pathogenesis of renal damage in PUJO.

Epidermal growth factor and monocyte chemotactic peptide-1 expression in reflux nephropathy

OBJECTIVES

Reflux nephropathy (RN) is recognised as a major cause of end stage renal failure in children and young adults. The histological findings of RN are tubular atrophy and interstitial monocyte infiltration. Epidermal growth factor (EGF) produced by tubular cells playing a pivotal role in the modulation of tubular cell growth, while monocyte chemotactic peptide-1 (MCP-1) is a powerful and specific chemotactic and activating factor for monocytes. It has been suggested that the modulation of local EGF production is directly involved in the pathogenesis of tubular damage. We designed this study to investigate the expression of EGF and MCP-1 in severe reflux nephropathy in order to further understand the pathogenesis of reflux nephropathy.

METHODS

The kidney specimens from 12 children with severe reflux nephropathy were obtained at the time of nephrectomy. Control material included normal kidney specimens obtained from three adult patients during partial nephrectomy for an incidentaloma. Single-label immunofluorescence histochemistry was carried out using polyclonal antibodies to EGF and MCP-1 employing laser scanning confocal microscopy. EGF and MCP-1 gene expression were evaluated by in situ hybridization (ISH). TUNEL method was utilized to assess tubular apoptosis.

RESULTS

In the normal kidney there was strong EGF immunoreactivity in the proximal tubules compared to the reflux nephropathy where there was lack of immunoreactivity in the proximal tubules. Normal kidney demonstrated lack of MCP-1 immunoreactivity, whereas reflux nephropathy kidney showed strong MCP-1 immunoreactivity in the proximal tubules and tubulointerstitial space. In the normal kidney there was marked EGF mRNA expression in the proximal tubules whereas EGF mRNA expression was undetectable in reflux nephropathy kidney. MCP-1 mRNA expression was undetectable in normal kidney, whereas there was strong MCP-1 mRNA expression at the tubulointerstitial level in reflux nephropathy kidney. Decreased EGF expression and increased MCP-1 expression at the tubulointerstitial levels in reflux nephropathy strongly correlated with severity of apoptosis in reflux nephropathy compared with controls.

CONCLUSIONS

Our data suggests that the downregulation of EGF with simultaneous upregulation of MCP-1 may be involved in the pathogenesis of tubulointerstitial damage in reflux nephropathy.