Major Contribution of the P2Y 1 Receptor in Purinergic Regulation of TNFα-Induced Vascular Inflammation

Abstract

Background— Atherosclerosis is an inflammatory disease, and extracellular nucleotides are one of the factors possibly involved in vascular inflammation. The P2Y 1 receptor for adenosine 5|o:-diphosphate has been shown to be involved in the development of atherosclerosis in apolipoprotein E–deficient mice. Our aim is to determine whether the endothelial P2Y 1 receptor plays a role in leukocyte recruitment during vascular inflammation and characterize underlying mechanisms. Methods and Results— We show here that the P2Y 1 receptor plays a role in leukocyte recruitment in inflamed mouse femoral arteries. Moreover, in wild-type bone marrow–transplanted chimeric P2Y 1 -deficient mice with an apolipoprotein E–deficient background, a strong reduction of adhesion molecule–dependent leukocyte recruitment was observed after local injection of tumor necrosis factor α and interleukin 1β, excluding a role for the platelet or other hematopoietic cell type P2Y 1 in these events. Similarly, the in vitro adhesion of isolated mouse monocytes to tumor necrosis factor α–stimulated murine endothelial cell monolayers and their migration across the cell layers were strongly reduced in P2Y 1 -deficient compared with wild-type endothelial cells, as was the expression of the adhesion molecules P-selectin, Vascular cell adhesion molecule 1, and intercellular adhesion molecule 1. Pharmacological inhibition using the selective antagonist MRS2500 also resulted in decreased expression of adhesion molecules. These events are related to the p38 mitogen-activated protein kinase and activating transcription factor 2 pathway. Finally, in vivo administration of MRS2500 resulted in strong reduction of leukocyte recruitment in inflamed femoral arteries of apolipoprotein E–deficient mice. Conclusions— The data highlight a key role of the endothelial P2Y 1 receptor in acute vascular inflammation. Pharmacological targeting the P2Y 1 receptor could represent a promising approach for the treatment of vascular inflammation.