Indoxyl sulfate inhibits nitric oxide production and cell viability by inducing oxidative stress in vascular endothelial cells.
OBJECTIVE
Cardiovascular disease is a major cause of mortality in chronic kidney disease patients. Oxidative stress and nitric oxide (NO) deficiency play an important role in vascular endothelial cell dysfunction in chronic kidney disease. To determine if the uremic toxin indoxyl sulfate (IS) induces oxidative stress and inhibits NO production and cell viability in human umbilical vein endothelial cells (HUVEC).


METHODS
The production of reactive oxygen species (ROS), superoxide, NO and peroxynitrite was measured using a fluorescence microplate reader. The expression of NADPH oxidases (Nox4, Nox2) was analyzed by quantitative reverse transcription-polymerase chain reaction. Cell viability was examined by 4-[3-(4-iodophenyl)-2-(4-nitrophenyl)-2H-5-tetrazolio]-1,3-benzene disulfonate assay.


RESULTS
IS induced ROS generation in HUVEC. An inhibitor of NADPH oxidase showed an inhibitory effect on IS-induced ROS production. However, the inhibitors of xanthine oxidase, mitochondrial electron transport and NO synthase did not show any significant effect on IS-induced ROS production. Antioxidants such as vitamin E, N-acetyl-L-cysteine and vitamin C inhibited IS-induced ROS production. IS induced the expression of Nox4 mRNA and the production of superoxide and peroxynitrite in HUVEC. IS inhibited NO production in HUVEC. IS inhibited cell viability, and antioxidants preserve the inhibitory effect of IS on cell viability.


CONCLUSIONS
IS inhibits NO production and cell viability by inducing ROS through induction of Nox4 in HUVEC.
Tumur
Zohra
Z
Department of Clinical Preventive Medicine, Nagoya University Hospital, Nagoya, Japan.
Niwa
Toshimitsu
T
D002470:Cell Survival; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000166:cytology; D006801:Humans; D007200:Indican / Q000378:metabolism*; D019255:NADPH Oxidases / Q000378:metabolism; D009569:Nitric Oxide / Q000096:biosynthesis*; D018384:Oxidative Stress; D030421:Peroxynitrous Acid / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism
D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D030421:Peroxynitrous Acid; D009569:Nitric Oxide; D019255:NADPH Oxidases; D007200:Indican