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=-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 ␣ and interleukin 1␤, 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 ␣-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. (Circulation. 2011;123:2404-2413.)Key Words: inflammation Ⅲ atherosclerosis Ⅲ receptors, purinergic P2 Ⅲ apolipoproteins Ⅲ endothelial cells V ascular inflammation is now considered to be the link between risk factors for atherosclerosis and the biology underlying its complications, among which arterial thrombosis is life threatening. 1 One of the key inflammatory responses of the endothelium is the exposure of adhesion molecules to recruit subsets of leukocytes, including neutrophils and monocytes, which play a pivotal role in the initiation and progression of atherosclerosis. [2][3][4] Members of the selectin family, like P-and E-selectin 5 and the immunoglobulin (Ig) family, notably intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1), 4,6 promote irreversible adhesion of monocytes to the endothelium and their transmigration into the subendothelial space. These adhesion molecules are upregulated by proinflammatory cytokines, such as tumor necrosis factor ␣ (TNF␣), the effects of which also include the i...

P2 receptors and platelet function

“…We recently reported that the P2Y 1 receptor contributes to the upregulation of adhesion molecule (P-selectin, VCAM-1 and ICAM-1) exposure in TNFα-stimulated ECs by a mechanism involving p38 MAP kinase signalling pathway, which in turn facilitates recruitment of monocytes and their transmigration. In addition, we found that the endothelial P2Y 1 receptor contributes to TNFα-induced leukocyte recruitment in experimentally inflamed arteries in a mouse model in vivo [127]. Thus, the P2Y 1 receptor might be an original target for new anti-inflammatory strategies.…”

“…It is worthy to note that inhibition of the P2Y 1 receptor results in only moderate prolongation of the bleeding time, which could be advantageous in terms of safety. Additional advantages of targeting the P2Y 1 receptor rely on its role in vascular inflammation [127] and in atherosclerosis [128] (see below). As a consequence, this receptor could represent an attractive and original target for drugs with multiple sites of action in atherothrombosis and beyond in other inflammatory diseases.…”

Function and Regulation of Pannexin 1 Channels in the Vascular Endothelium

“…In addition, TNFα upregulated P2Y6 receptor expression in endothelial cells, further suggesting a direct role for purinergic signaling in this inflammation model [16]. In a separate study, endothelial cell P2Y1 receptors were shown to regulate TNFα-and IL-1β-induced adhesion molecule expression on cultured ECs and genetic ablation of P2Y1 decreased leukocyte rolling and adhesion in response to infusion of the cytokines [17]. Together, these studies point towards a direct role for purinergic receptors in promoting an inflammatory endothelial cell phenotype.…”

“…The effects of ATP signaling have been observed throughout the vasculature in both homeostatic and pathological conditions, including: reactive hyperemia [7,8], hypoxiainduced vasodilation [9,10], alpha-adrenergic receptor mediated vasoconstriction [11], hypertension [12], VSMC proliferation in atherosclerosis and vascular inflammation [13][14][15][16][17]. Elucidation of the mechanisms regulating purine nucleotide release in the cells comprising the vascular wall is critical for both understanding the pathogenesis of vascular diseases and the identification of novel drug interventions.…”

“…In addition, neutrophils themselves can release ATP to modulate the relative permeability of the vascular endothelium supplying inflamed tissues [79]. At the level of the vascular endothelium, purinergic P2Y6 and P2Y1 receptor signaling has been directly linked to the acute inflammatory response [16,17]. Genetic deletion of endothelial cell P2Y6 receptors potently inhibited neutrophil interactions with the venous endothelium in response to a lipopolysaccharide (LPS) model of systemic inflammation.…”