Clin Res Cardiol (2022). https://doi.org/10.1007/s00392-022-02002-5
P2Y12 receptor blockers are anti-inflammatory drugs inhibiting both circulating monocytes and resident macrophages
P. M. Siegel1, L. Sander2, A. Fricke2, J. Stamm2, X. Wang2, P. Sharma2, N. Bassler2, Y.-L. Ying2, C. Olivier1, S. Eisenhardt3, C. Bode1, I. Ahrens4, P. Diehl5, K. Peter6
1Klinik für Kardiologie und Angiologie I, Universitäts-Herzzentrum Freiburg - Bad Krozingen GmbH, Freiburg im Breisgau; 2Baker Heart Research Institute, Central Melbourne, AU; 3Klinik für Plastische Chirurgie und Handchirurgie, Universitätsklinikum Freiburg, Freiburg; 4Klinik für Kardiologie und internistische Intensivmedizin, Krankenhaus der Augustinerinnen, Akademisches Lehrkrankenhaus, Köln; 5Kardiologie, Ortenau-Klinikum Lahr-Ettenheim, Lahr/Schwarzwald; 6Centre of Thrombosis and Myocardial Infarction, Baker Heart Research Institute, Central Melbourne, AU;
Introduction: P2Y12 receptor blockade improves patient outcomes after myocardial infarction. In addition to well described antithrombotic effects, anti-inflammatory effects may contribute to these clinical benefits. The conformation-specific single chain variable fragment (scFv) MAN-1 detects the activated conformation of the leukocyte integrin Mac-1 on monocytes and macrophages and therefore represents a unique tool to assess the activation level of these cells. The aim of this study was to identify potential anti-inflammatory effects of P2Y12 receptor blockers on monocytes and macrophages. 
Methods: Using flow cytometry, migration assays, flow chambers and RNA microarrays, we investigated the effects of adenosine diphosphate (ADP) and P2Y12 receptor blockers on blood monocytes obtained by different isolation methods, THP-1 monocytes and THP-1 cells after differentiation to macrophages. 
Results: Platelets, which endogenously express P2Y12 receptors, form aggregates with monocytes in circulating blood at various degrees depending on the method of monocyte isolation. Mediated by platelet P2Y12 receptors, ADP stimulation leads to activation of the leukocyte integrin Mac 1 on blood monocytes within platelet-monocyte-aggregates, as detected by the conformation-specific scFv MAN-1. ADP stimulation via the same association with platelets also promotes THP-1 monocyte adhesion to the endothelial intercellular adhesion molecule 1 (ICAM-1). P2Y12 receptor blockers, for example cangrelor, prevent these ADP effects on monocytes. In contrast to monocytes, THP-1 cells, which have been differentiated to macrophages, express the P2Y12 receptor endogenously and consequently ADP was found to be a potent activator and chemoattractant. P2Y12 receptor blockers inhibited this effect. Accordingly, stimulation of THP-1 macrophages with ADP caused a significant change in gene expression patterns and upregulation of several genes associated with inflammation and atherosclerosis. 
Conclusion: P2Y12 receptor blockers exert potent anti-inflammatory effects on monocytes and macrophages, although by different mechanisms. These findings provide a novel explanation for the reduction of cardiovascular risk by P2Y12 receptor blockers as observed in large clinical trials. 

 
Figure 1. ADP-stimulated monocyte platelet aggregates bind to ICAM-1 under shear flow. Binding is reduced by incubation with different P2Y12 receptor blockers (2MesAMP, cangrelor and the active metabolite of prasugrel. n = 5, p represents the significance level as determined by ANOVA and a Tukey’s post hoc test.
https://dgk.org/kongress_programme/jt2022/aP1955.html