Lipoprotein oxidation,
inflammation, and immune responses involving the vascular endothelium and immune cells contribute to the pathogenesis of
atherosclerosis. In an atherosclerotic animal model,
P2Y2 receptor (P2Y2R) upregulation and stimulation were previously shown to induce intimal
hyperplasia and increased intimal monocyte infiltration. Thus, we investigated the role of P2Y2R in
oxidized low-density lipoprotein (
oxLDL)-mediated oxidative stress and the subsequent interaction between endothelial cells (ECs) and immune cells. The treatment of human ECs with
oxLDL caused the rapid release of
ATP (maximum after 5 min). ECs treated with
oxLDL or the P2Y2R agonists
ATP/
UTP for 1h exhibited significant
reactive oxygen species (ROS) production, but this effect was not observed in P2Y2R
siRNA-transfected ECs. In addition,
oxLDL and
ATP/
UTP both induced RAGE expression, which was P2Y2R dependent.
Oxidized LDL- and
ATP/
UTP-mediated ROS production was diminished in RAGE
siRNA-transfected ECs, suggesting that RAGE is an important mediator in P2Y2R-mediated ROS production. Treatment with
oxLDL for 24h induced P2Y2R expression in the human monocyte cell line THP-1 and increased THP-1 cell migration toward ECs. The addition of
apyrase, an
enzyme that hydrolyzes
nucleotides, or
diphenyleneiodonium (DPI), a well-known inhibitor of
NADPH oxidase, significantly inhibited the increase in cell migration caused by
oxLDL. P2Y2R
siRNA-transfected THP-1 cells did not migrate in response to
oxLDL or
ATP/
UTP treatment, indicating a critical role for P2Y2R and
nucleotide release in
oxLDL-induced monocyte migration. Last,
oxLDL and
ATP/
UTP effectively increased
ICAM-1 and
VCAM-1 expression and the subsequent binding of THP-1 cells to ECs, which was inhibited by pretreatment with DPI or by
siRNA against P2Y2R or RAGE, suggesting that P2Y2R is an important mediator in
oxLDL-mediated monocyte adhesion to ECs through the regulation of ROS-dependent adhesion molecule expression in ECs. Taken together, our findings suggest that P2Y2R could be a therapeutic target for the prevention of vascular disorders, including
atherosclerosis.