Recombinant human erythropoietin attenuates renal tubulointerstitial injury in murine adriamycin-induced nephropathy

Abstract

Erythropoietin (EPO) has been found to provide cytoprotection against acute ischemic and toxic renal tubulointerstitial injury. This study aimed to elucidate the mechanism(s) underlying EPO protection while examining whether EPO provides tubulointerstitial protection in a mouse model with adriamycin (ADR)-induced tubulointerstitial injury. Adriamycin nephropathy (AN) was induced by a single injection of ADR in the 2 experimental groups on day 0. The saline-control group and the AN-saline group were administered saline at days 7, 14, and 21, while the EPO-control group and the AN-EPO group were administered EPO at days 7, 14, and 21. Kidneys were harvested at days 14 and 28 after ADR injection to measure the expression levels of the EPO receptor (EPO-R), CD34, and phosphorylated Akt by immunohistochemistry; to determine the extent of apoptosis by terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) and active caspase-3 staining; and to map the hypoxic area by pimonidazole staining. EPO-R was detected in glomerular, tubular epithelial, and endothelial cells. EPO administration significantly improved tubulointerstitial injury, decreased the number of TUNEL-positive and active caspase-3-positive cells, and increased the phosphorylated-Akt-positive area in the tubulointerstitial area without increasing the hemoglobin or hematocrit levels. EPO provides renoprotection against AN by reducing apoptotic cell death and preserving peritubular capillaries, possibly by exerting pleiotropic effects independently of its hemopoietic effects.