Hydronephrosis Promotes Expression of Hypoxia-Inducible Factor 1α

Abstract

Background: Obstructive uropathy is argued to involve an ischemia-type tissue injury. Further, hypoxia-inducible factor 1α (HIF-1α) constitutes a nuclear transcription factor normally upregulated under hypoxic conditions. We hypothesized that HIF-1α is expressed in the hydronephrotic renal pelvis, as a result of tissue hypoxia. Patients and Methods: Renal pelvis tissue specimens were obtained from 2 patient groups. Group 1 (controls, n = 10) consisted of patients who underwent nephrectomy due to nonobstructive renal malignancy. Group 2 (n = 18) consisted of patients who underwent open procedures due to intractable hydronephrosis, not amenable to conservative measures. HIF-1α detection was conducted via immunohistochemical techniques, while histological alterations in both groups were also recorded. Results: Smooth muscle hypertrophy and urothelial hyperplasia were major findings in group 2. HIF-1α-positive cells (fibroblasts and occasionally macrophages), mainly localized in the stroma, were also found to a greater extent in group 2 (p = 0.0066). Conclusion: We conclude that HIF-1α is mainly expressed in stroma fibroblasts of the hydronephrotic renal pelvis, implying the presence of significant tissue hypoxia at the dilated upper urinary tract.