P2X deficiency reduces atherosclerosis and plaque inflammation in mice.

Extracellular adenosine-5'-triphosphate (ATP) acts as an import signaling molecule mediating inflammation via purinergic P2 receptors. ATP binds to the purinergic receptor P2X and promotes inflammation via increased expression of pro-inflammatory cytokines. Because of the central role of inflammation, we assumed a functional contribution of the ATP-P2X-axis in atherosclerosis. Expression of P2X was increased in atherosclerotic aortic arches from low-density lipoprotein receptor-deficient mice being fed a high cholesterol diet as assessed by real-time polymerase chain reaction and immunohistochemistry. To investigate the functional role of P2X in atherosclerosis, P2X-deficient mice were crossed with low-density lipoprotein receptor-deficient mice and fed high cholesterol diet. After 16 weeks, P2X-deficient mice developed smaller atherosclerotic lesions compared to P2X-competent mice. Furthermore, intravital microscopy showed reduced ATP-induced leukocyte rolling at the vessel wall in P2X-deficient mice. Mechanistically, we found a reduced RNA expression of CC chemokine ligand 2 (CCL-2), C-X-C motif chemokine-1 (CXCL-1), C-X-C motif chemokine-2 (CXCL-2), Interleukin-6 (IL-6) and tumor necrosis factor α (TNFα) as well as a decreased nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3)-inflammasome priming in atherosclerotic plaques from P2X-deficient mice. Moreover, bone marrow derived macrophages isolated from P2X-deficient mice revealed a reduced ATP-mediated release of CCL-2, CC chemokine ligand 5 (CCL-5), Interleukin-1β (IL-1β) and IL-6. Additionally, P2X-deficient mice shared a lower proportion of pro-inflammatory Ly6C monocytes and a higher proportion of anti-inflammatory Ly6C monocytes, and expressend less endothelial VCAM-1. Finally, increased P2X expression in human atherosclerotic lesions from carotid endarterectomy was found, indicating the importance of potential implementations of this study's findings for human atherosclerosis. Collectively, P2X deficiency reduced experimental atherosclerosis, plaque inflammation and inflammasome priming, pointing to P2X as a potential therapeutic target in the fight against atherosclerosis.