Indoxyl Sulfate Induces Endothelial Cell Senescence by Increasing Reactive Oxygen Species Production and p53 Activity

Background/Aim: We have reported that indoxyl sulfate (IS), a uremic toxin, accelerates proximal tubular cell senescence. Asymmetric dimethylarginine (ADMA), an inhibitor of nitric oxide synthase, has been reported to induce endothelial cell senescence. This study aimed to determine whether IS induces endothelial cell senescence in comparison with ADMA, and to investigate its molecular mechanism. Methods: Human umbilical vein endothelial cells (HUVECs) were incubated with IS (250 mu M) and/or ADMA (10 mM). These concentrations were comparable with their mean serum levels in hemodialysis patients. Cell senescence was evaluated by measuring senescence-associated beta-galactosidase (SA-beta-gal) activity. N-acetylcysteine, an antioxidant, and pifithrin alpha p-nitro, a p53 inhibitor, were used to determine the role of reactive oxygen species (ROS) and p53 in the induction of cell senescence. Results: Both IS and ADMA significantly increased SA-b-gal activity in HUVECs. Further, some additional increase in SA-b-gal activity was observed when IS and ADMA were co-incubated. Preincubation of N-acetylcysteine or pifithrin alpha p-nitro significantly inhibited SA-b-gal activity induced by IS and ADMA in HUVECs. Thus, both IS and ADMA induced endothelial senescence through ROS and p53. Conclusion: IS induces endothelial cell senescence by increasing ROS production and p53 activity, like ADMA. (C) 2012 by the National Kidney Foundation, Inc. All rights reserved.