• Ramune Zilinskaite Tamasauske, Vytis Kazlauskas, Povilas Barasa, Natalija Krestnikova, Darius Dasevicius, Vytautas Bilius, and Gilvydas Verkauskas.
• Clinic of Gastroenterology, Nephrourology and Surgery, Institute of Clinical Medicine, Faculty of Medicine, Vilnius University, 10257 Vilnius, Lithuania.
• Medicina (Kaunas). 2023 Sep 27; 59 (10).

AbstractBackground and Objectives: Congenital ureteral stenosis is one of the leading causes of impaired urinary drainage and subsequent dilatation of the urinary collecting system, known as hydronephrosis or ureterohydronephrosis. The mechanism that leads to obstruction is not clearly known. Multiple studies in rat models have shown increased angiotensin II and TGFβ levels in obstructed ureteral tissue. The aim of the study is to investigate the expression of fibrosis-related genes in obstructive and normal ureteral tissue. Material and Methods: It is a monocentric pilot study in which nineteen patients were selected prospectively. 17 patients underwent Hynes-Anderson pyeloplasty due to the PUJO; two patients underwent ureteroneocystostomy due to ureterovesical junction obstruction (UVJO); and six patients were chosen for the control group: five underwent nephrectomies due to the kidney tumor and one underwent upper pole heminephrectomy due to the duplex kidney with normal pyeloureteric junctions in all. Tissue RNA was chemically extracted after freezing the biopsy samples in liquid nitrogen, with cDNA synthesis performed immediately after nucleic acid isolation. qPCR was performed to evaluate the relative expression of Tgfb1, Mmp1, Timp1, Pai1, Ctgf, and Vegfa. Expression levels of the Gapdh and Gpi genes (geometric average) were used to calculate the relative expression of the investigated genes. Outliers were removed prior to calculating confidence intervals for the experimental groups, and a Wilcoxon rank-sum test was performed to determine the statistical significance of the differences. Results: Significant differences between healthy and stenotic tissue samples in Ctgf gene expression levels were observed, with the samples from afflicted tissue showing lower expression. No statistical difference in expression levels of Tgfb1, Timp1, Vegfa, Mmp1, and Pai1 was found. Conclusions: These findings suggest that tissue fibrosis, similar to other tissues and organs, is not the leading cause of stenosis, at least at the moment of surgery. Decreased CTGF expression is indicative of the developmental origin of obstruction.

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