Increased inorganic phosphate induces human endothelial cell apoptosis in vitro.
Chronic kidney disease with hyperphosphatemia is associated with accelerated atherosclerosis and endothelial dysfunction. However, the contribution of high serum phosphate levels to endothelial injury is incompletely understood. The aim of this work was to evaluate the responses of endothelial cells to elevated levels of extracellular phosphate in vitro. High phosphate in concentrations similar to those observed in uremia-associated hyperphosphatemia (>2.5 mM) induced apoptosis in two endothelial cell lines (EAhy926 cells and GM-7373 cells). This effect was enhanced when cells were incubated for 24 h in the presence of 2.8 mM calcium instead of 1.8 mM. By treating cells with 0.5 or 1.0 mM phosphonoformic acid, an inhibitor of the phosphate transporter, death was completely prevented. The process of phosphate-induced apoptosis was further characterized by increased oxidative stress, as detected by increased ROS generation and disruption of the mitochondrial membrane potential at approximately 2 h after treatment, followed by caspase activation. These findings show that hyperphosphatemia causes endothelial cell apoptosis, a process that impairs endothelial integrity. Endothelial cell injury induced by high phosphate concentrations may be an initial event leading to vascular complications in patients with chronic kidney disease.
Di Marco
G S
GS
Department of Internal Medicine, University Clinics Muenster, D48149 Münster, Germany. giodimarco@gmail.com
Hausberg
M
M
Hillebrand
U
U
Rustemeyer
P
P
Wittkowski
W
W
Lang
D
D
Pavenstädt
H
H
D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D050197:Atherosclerosis / Q000378:metabolism / Q000473:pathology; D002118:Calcium / Q000494:pharmacology; D061945:Caspase Inhibitors; D002478:Cells, Cultured; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D042783:Endothelial Cells / Q000166:cytology* / Q000187:drug effects*; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D054559:Hyperphosphatemia / Q000378:metabolism / Q000473:pathology*; D066298:In Vitro Techniques; D007676:Kidney Failure, Chronic / Q000378:metabolism / Q000473:pathology; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D010710:Phosphates / Q000494:pharmacology*; D017382:Reactive Oxygen Species / Q000378:metabolism; D050608:Sodium-Phosphate Cotransporter Proteins / Q000235:genetics; D014471:Umbilical Veins / Q000166:cytology
D000590:Amino Acid Chloromethyl Ketones; D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; D010710:Phosphates; D017382:Reactive Oxygen Species; D050608:Sodium-Phosphate Cotransporter Proteins; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D002118:Calcium