Renal expression of hypoxia inducible factor-1α in patients with chronic kidney disease

Background & objectives: Hypoxia inducible factor-1α (HIF-1α) has been shown to play a role in the pathogenesis of renal interstitial fibrosis. However, the relationship of HIF-1α expression intensity in human renal tissue with the degree of renal function or renal fibrosis has not been investigated. We therefore, undertook this study to assess the relationship between HIF-1α expression and degree of renal impairment and renal fibrosis using renal tissue from nephrectomized kidneys from patients with chronic kidney disease. Methods: This retrospective study was performed with 70 patients undergoing unilateral or bilateral nephrectomy because of renal cell carcinoma, urothelial cell carcinoma, or renal abscess. Immunohistochemical analysis of HIF-1α expression in non-tumourous or non-abscess renal parenchyma was performed. The patients were divided into two groups: group 1 (n=37) with low intensity HIF-1α expression and group 2 (n=33) with high intensity HIF-1α expression. Results: The intensity of renal HIF-1α expression was significantly associated with serum creatinine level (P=0.005), estimated glomerular filtration rate (P=0.02), fibrosis score of the interstitium (P=0.004) and glomerular sclerosis (P=0.013). A high intensity of HIF-1α expression tended to be associated with lower serum creatinine, higher estimated glomerular filtration rate, low interstitial fibrosis score and low glomerular sclerosis. In addition, multivariate analysis by step-wise logistic regression demonstrated that interstitial fibrosis was the only independent factor associated with the intensity of renal HIF-1α expression (OR 4.107, CI 1.535-11.313, P=0.005). Interpretation & conclusions: This study demonstrated a correlation between intensity of HIF-1α expression and degree of renal interstitial fibrosis. The association demonstrated an elevated HIF-1α expression in less severe kidney disease. The intensity of HIF-1α renal expression plays a role in the pathogenesis of chronic kidney disease.