Protective effects of BMP-7 against aristolochic acid-induced apoptosis of renal tubular epithelial cells

Objective To investigate the toxicity of aristolochic acid(AA) at different concentrations on renal tubular epithelial cells(RTECs) and to evaluate the protective effects of BMP-7 on AA-induced apoptosis of RTECs. Methods (1) Human proximal tubular epithelial cells(HK-2 cells) were stimulated with AA at 5,10,20,40,80 and 160 μg/mL in vitro.Cellular apoptosis,morphological and nuclear morphological changes were assessed using lactate dehydrogenas(LDH) release assay,inverted phase contrast microscope and Hoechst 33258 staining,respectively.(2) AA(20 μg/mL and 40 μg/mL)-induced HK-2 cells were treated with BMP-7 in 300 ng/mL for 48 h.Cell apoptosis was subsequently assessed by Hoechst 33258 staining,and caspase-3 activity measured by spectrophotometry. Results LDH release significantly increased as AA reached 80 μg/mL(P0.001).Meanwhile,apoptotic rate significantly increased when AA reached 10 μg/mL,and peaked with AA at 40 μg/mL.BMP-7 treatment,however,significantly reduced AA-induced HK-2 cells apoptosis and caspase-3 activity(P0.01). Conclusion High-dose AA induces RTECs necrosis,while low dose of AA induces apoptosis.BMP-7 reduces AA-induced apoptosis,partly by inhibiting caspase-3 activity.