Expression of HO-1 in chronic renal insufficiency. Rat kidney and implication.

The expression, activity and clinical implication of heme oxygenase-1 (HO-1) in the chronic renal insufficiency (CRI) rat kidney and its mechanism were investigated. The 5/6 nephrectomized rats were assigned to sham operation group, CRI group and Hemin group. At the 8th week after second operation, blood pressure, urinary protein, serum creatinine (Scr) and BUN were measured. Renal pathologic changes were observed. The activity of HO and contents of erythropoietin (EPO) in serum and renal tissue were determined. Immunohistochemistry was used to detect the expression and distribution of HO-1 in the CRI rat kidney. As compared with CRI group, the urinary protein, blood pressure, Scr and BUN in Hemin group were reduced significantly (P < 0.05). The glomerular mesangial proliferation, inflammatory cellular infiltration of renal interstitium and interstitial fibrosis were ameliorated significantly. Immunohistochemistry and measurement of HO-1 activity revealed that the expression and activity of HO-1 was decreased in renal tissues and increased in serum in CRI group as compared with normal rats. HO-1 distributed mainly in tubular epithelial cells. The EPO contents in Hemin group were significantly higher than in CRI group. Through up-regulating the EPO level in serum and renal tissues, HO-1 retards the progression of CRI.