Protective effect of erythropoietin against aristolochic acid-induced apoptosis in renal tubular epithelial cells

The goal of this research was to investigate the renoprotective effect of erythropoietin against aristolochic acid-induced apoptosis in cultured LLC-PK1 cells as well as underlying mechanism. LLC-PK1 cells impaired by aristolochic acid were used in this study as the cell model of aristolochic acid nephropathy. Apoptosis was studied by different methods (transmission electron microscopy, fluorescence-activated cell sorting, TUNEL, caspase-3 activation). Cells showed apoptotic morphology when exposed to 10 mu g/ml aristolochic acid for 24 h, and the apoptotic index was increased (37.67%) compared with the control (6.09%). The presence of recombinant human erythropoietin (10, 20 U/ml, 24 h) significantly lowered the apoptotic index (22.41%, 14.63%) and the damage of cytoskeleton was also ameliorated. Studies on the apoptotic signaling showed that recombinant human erythropoietin inhibited the activation of caspase-3 and upregulated the expression of anti-apoptotic gene, Bcl-XL Moreover, recombinant human erythropoietin (10, 20 U/ml, 24 h) promoted the expression of proliferating cell nuclear antigen in renal tubular cells stimulated by 10 mu g/ml aristolochic acid (46.34%, 48.11% vs. 28.46%). Together, our data provide in vitro evidence that recombinant human erythropoietin mediated renoprotective effect against aristolochic acid injury in renal tubular cells by ameliorating the damage of cytoskeleton, reducing the number of apoptotic cells and promoting cell regeneration. So a possibility is suggested that recombinant human erythropoietin may be beneficial in preventing aristolochic acid-induced apoptosis and could be a new promising therapeutic strategy for aristolochic acid-induced kidney damage. (C) 2008 Elsevier B.V. All rights reserved.