Cytokine-Enzymatic Biomarkers for Restoration of the Functional State of Renal Parenchyma in Children After Reconstractive Correction of Congenital Defects of the Uretero-Vesical Segment

Abstract

The aim of this study was to study the peculiarities of changes in cytokine excretion levels of transforming growth factor b1 (TGF-b1), tumor necrosis factor a (TNF-a), monocytic chemoattractant protein 1 (MCP-1) and urinary activity of conditionally renospecific enzymes g-glutamyltranspeptidase (GGT) and neutral a-gtlucosidase (NG) as biomarkers of restoration of the functional state of the kidney parenchyma in children at different times after reconstructive correction of congenital defects of the uretero-vesical segment (UVS). 
 Materials and Methods. Prior to reconstructive correction of congenital defects of UVS the comprehensive clinical and laboratory study was conducted in 45 children aged 4 to 15 years (22 boys, 23 girls) who were diagnosed with megaureter (MU) according to visualization methods: 18 patients with non-refluxing MU (NRMU) and 27 patients with refluxing MU (RMU). 3-4 patients were examined 3-4 weeks after the operation and 24 patients 4-6 months later. The study did not include children with neurogenic bladder dysfunction and pyelonephritis. All patients underwent transvesical ureterocystoneostomy. The reference group consisted of 25 healthy children with normal urinalysis and without an uronephrological pathology. Determination of TNF-a, TGF-b1 and MCP-1 was carried out in urine by the enzyme immunoassay. The results were expressed in units of mass of the substance in terms of unit volume of urine (pg/ml). The activity of GGT and NG was determined by a colorimetric method in our modification using reagent kits. The activity of enzymes in urine was expressed in relative units – in micromoles of reaction products formed after 1 hour of incubation 1 mmol of urine creatinine (µmol/hour/mmol creatinine). We also took into account the fluctuation limits of all investigated indicators. 
 Results. The comparative analysis of TGF-b1, TNF-a, GGT and NG in children with congenital UVS defects before reconstructive operations and the control group demonstrated the statistically reliable difference (p < 0.001). It was stated that in urine of the control group the levels of pro-inflammatory cytokine MCP-1 are not defined at all. The study of this cytokine as a diagnostic and prognostic index of the functional state of renal parenchyma, according to our results, is not advisable. It was also stated that in patients with RMU (baseline) there is an increase in both TGF-b1 and TNF-a levels and the levels of GGT and NG activity compared with the group of patients with congenital NRMU. 3-4 weeks after reconstructive surgery, the levels of TNF-a and the levels of activity GGT and NG urine did not decrease, levels of TGF-b1, on the contrary, even increased. A personalized analysis of the results 4 to 6 months after the transvesical reconstruction revealed that 33.3% of patients showed normalization of TGF-b1 levels (p < 0.001) and a significant decrease in TNF-a, the levels of GGT and urinary NG activity practically reach the range of control. In other cases, despite the recovery of upper urinary tract dynamics, the levels of TNF-a, TGF-b1 and the activity of GGT and NG continued to remain at a fairly high level. 
 Conclusions. The levels of TNF-a and TGF-b1 as well as the levels of activity of conditionally renospecific enzymes GGT and NG of urine in children with congenital malformations of UVS are diagnostically informative biomarkers about progression of pathological process in the kidney and negative influence of pronounced dysfunction of urinary bladder on the pro-inflammatory and pro-fibrotic processes of renal parenchyma in the postoperative period. Taking into account that in 66.7% of cases in children with congenital UVS defects after ureterocystoneostomy disorders in the function of the tubular apparatus of the renal parenchyma and signs of tubulointerstitial fibrosis persist, it is advisable to distinguish these patients into a separate group to avoid the risk for the development of nephrosclerotic disease and to start modern renoprotective therapy timely.