Pelviureteral junction obstruction: correlation of renal cell apoptosis and differential renal function

We evaluated the relationship between renal biopsy changes and preoperative and postoperative renal scans in 29 male and 14 female infants with prenatal severe hydronephrosis and unilateral ureteropelvic junction obstruction. We also verified on immunohistochemical studies glomerular changes, degeneration of the epithelium of the proximal tubules, interstitial fibrosis and inflammation and apoptotic nuclei.

In the children, all with prenatal diagnosis of hydronephrosis, ureteropelvic junction obstruction was diagnosed with 99mtechnetium mercaptoacetyltriglycine renal scan performed in all patients at ages 4 to 6 weeks to establish baseline differential renal function. All patients underwent renal biopsies at the time of pyeloplasty. The biopsy samples were examined with histological and immunohistochemical methods for antigens associated with apoptosis, such as clusterin, CD95, TDAG51 and bcl-2. Renograms were performed 3 months after surgical repair.

The male-to-female ratio was 2.1:1. There was no difference between males and females in regard to baseline differential renal function of the affected kidney. All biopsy samples confirmed degeneration of the epithelium of the proximal tubules, interstitial focal fibrosis was found in 4 samples, mild chronic inflammation with lymphoid aggregates in 4 and focal Bowman's space dilatation in 1. No specimen demonstrated apoptotic nuclei as confirmed by immunohistochemical study which showed the presence of bcl-2 and absence of CD95, TDAG51 and clusterin, probably because there was no dysplasia in the samples examined.

These results indicate absence of apoptosis in the kidney with preoperative uptake less than 40% and minimal histological changes.