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Vidhya M. P2Y12 receptor residues crucial for thrombosis regulation. J Mol Recognit 2023; 36:e3056. [PMID: 37696759 DOI: 10.1002/jmr.3056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 07/01/2023] [Accepted: 08/28/2023] [Indexed: 09/13/2023]
Abstract
Thrombosis, or the formation of blood clots, can lead to serious medical conditions such as stroke, heart attack, and deep vein thrombosis. The purinoreceptor P2Y12 plays a critical role in the thrombotic pathway and is targeted for therapy to prevent clot formation. However, it is essential to balance the regulation of thrombosis to avoid adverse situations. This study focuses on the P2Y12 receptor and aims to discern the protein residue network and differentiate residues based on their intramolecular interactions. The study utilized a statistical analysis to characterize the significant residues involved in ligand interaction, which helps to identify critical residues that are essential for the function of the receptor. A parametric analysis of interactions of residues in the intraprotein interaction was conducted, which revealed significant residue-based contacts that facilitate protein interactions. By examining the interactions between residues, the mechanisms underlying protein interactions were studied and the importance of specific residues in facilitating these interactions was determined. This research provides important information on P2Y12, and the findings based on the network based significance of interacting residues may contribute to the development of new therapies that target the receptor to prevent clot formation while maintaining a balance in thrombosis regulation to avoid adverse outcomes. Ultimately, this study could lead to improved treatments for thrombotic disorders and better patient outcomes.
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Affiliation(s)
- M Vidhya
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, India
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Tyrosine Kinase Inhibitor Sunitinib Delays Platelet-Induced Coagulation: Additive Effects of Aspirin. Thromb Haemost 2021; 122:92-104. [PMID: 34130349 DOI: 10.1055/s-0041-1730312] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
BACKGROUND Sunitinib is a multitarget tyrosine kinase inhibitor (TKI) used for cancer treatment. In platelets, sunitinib affects collagen-induced activation under noncoagulating conditions. We investigated (1) the effects of sunitinib on thrombus formation induced by other TK-dependent receptors, and (2) the effects under coagulating conditions. Cardiovascular disease is a comorbidity in cancer patients, resulting in possible aspirin treatment. Sunitinib and aspirin are associated with increased bleeding risk, and therefore we also investigated (3) the synergistic effects of these compounds on thrombus and fibrin formation. METHODS Blood or isolated platelets from healthy volunteers or cancer patients were incubated with sunitinib and/or aspirin or vehicle. Platelet activation was determined by TK phosphorylation, flow cytometry, changes in [Ca2+]i, aggregometry, and whole blood perfusion over multiple surfaces, including collagen with(out) tissue factor (TF) was performed. RESULTS Sunitinib reduced thrombus formation and phosphatidylserine (PS) exposure under flow on collagen type I and III. Also, sunitinib inhibited glycoprotein VI-induced TK phosphorylation and Ca2+ elevation. Upon TF-triggered coagulation, sunitinib decreased PS exposure and fibrin formation. In blood from cancer patients more pronounced effects of sunitinib were observed in lung and pancreatic as compared to neuroglioblastoma and other cancer types. Compared to sunitinib alone, sunitinib plus aspirin further reduced platelet aggregation, thrombus formation, and PS exposure on collagen under flow with(out) coagulation. CONCLUSION Sunitinib suppresses collagen-induced procoagulant activity and delays fibrin formation, which was aggravated by aspirin. Therefore, we urge for awareness of the combined antiplatelet effects of TKIs with aspirin, as this may result in increased risk of bleeding.
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Liu W, Li YL, Feng MT, Zhao YW, Ding X, He B, Liu X. Application of Feedback System Control Optimization Technique in Combined Use of Dual Antiplatelet Therapy and Herbal Medicines. Front Physiol 2018; 9:491. [PMID: 29780330 PMCID: PMC5945866 DOI: 10.3389/fphys.2018.00491] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Accepted: 04/17/2018] [Indexed: 11/13/2022] Open
Abstract
Aim: Combined use of herbal medicines in patients underwent dual antiplatelet therapy (DAPT) might cause bleeding or thrombosis because herbal medicines with anti-platelet activities may exhibit interactions with DAPT. In this study, we tried to use a feedback system control (FSC) optimization technique to optimize dose strategy and clarify possible interactions in combined use of DAPT and herbal medicines. Methods: Herbal medicines with reported anti-platelet activities were selected by searching related references in Pubmed. Experimental anti-platelet activities of representative compounds originated from these herbal medicines were investigated using in vitro assay, namely ADP-induced aggregation of rat platelet-rich-plasma. FSC scheme hybridized artificial intelligence calculation and bench experiments to iteratively optimize 4-drug combination and 2-drug combination from these drug candidates. Results: Totally 68 herbal medicines were reported to have anti-platelet activities. In the present study, 7 representative compounds from these herbal medicines were selected to study combinatorial drug optimization together with DAPT, i.e., aspirin and ticagrelor. FSC technique first down-selected 9 drug candidates to the most significant 5 drugs. Then, FSC further secured 4 drugs in the optimal combination, including aspirin, ticagrelor, ferulic acid from DangGui, and forskolin from MaoHouQiaoRuiHua. Finally, FSC quantitatively estimated the possible interactions between aspirin:ticagrelor, aspirin:ferulic acid, ticagrelor:forskolin, and ferulic acid:forskolin. The estimation was further verified by experimentally determined Combination Index (CI) values. Conclusion: Results of the present study suggested that FSC optimization technique could be used in optimization of anti-platelet drug combinations and might be helpful in designing personal anti-platelet therapy strategy. Furthermore, FSC analysis could also identify interactions between different drugs which might provide useful information for research of signal cascades in platelet.
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Affiliation(s)
- Wang Liu
- Institute of Interdisciplinary Integrative Biomedical Research, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Yu-Long Li
- Institute for Personalized Medicine, State Key Laboratory of Oncogenes and Related Genes, School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Mu-Ting Feng
- Department of Cardiology, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Yu-Wei Zhao
- Department of Cardiology, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Xianting Ding
- Institute for Personalized Medicine, State Key Laboratory of Oncogenes and Related Genes, School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Ben He
- Department of Cardiology, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Xuan Liu
- Institute of Interdisciplinary Integrative Biomedical Research, Shanghai University of Traditional Chinese Medicine, Shanghai, China
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Florian P, Wonerow P, Harder S, Kuczka K, Dubar M, Graff J. Anti-GPVI Fab SAR264565 effectively blocks GPVI function in ex vivo human platelets under arterial shear in a perfusion chamber. Eur J Clin Pharmacol 2017; 73:949-956. [PMID: 28523478 DOI: 10.1007/s00228-017-2264-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Accepted: 05/03/2017] [Indexed: 12/21/2022]
Abstract
INTRODUCTION Glycoprotein VI (GPVI) is the major platelet receptor for collagen-mediated platelet adhesion and activation. SAR264565 is an anti-GPVI-Fab, binds to GPVI with high affinity, and blocks GPVI function in human platelets in vitro. METHODS The effect of SAR26456 on platelet responsiveness in the blood of 21 healthy male subjects was investigated using Sakariassen's ex vivo thrombogenesis perfusion chamber model on a collagen-coated surface under conditions mimicking arterial flow. Ex vivo effects of SAR264565 (10 and 100 μg/mL) were investigated before administration of aspirin or clopidogrel to study subjects (baseline), after aspirin (2× 300 mg) administration alone, and after combined aspirin (2× 300 mg)/clopidogrel (600 mg) administration. Additional ex vivo and in vitro platelet tests were also performed. RESULTS Addition of SAR264565 to the perfusion chamber dose-dependently reduced platelet and fibrin deposition, reaching statistical significance at 100 μg/mL (415 ± 67 compared to 137 ± 36 platelets/cm2, [p < 0.01] and fibrin 0.095 ± 0.014 compared to 0.032 ± 0.008 μg/cm2, [p < 0.001]). Aspirin administration caused an additive and dose-dependent reduction of SAR264565-induced platelet and fibrin deposition. Combined aspirin/clopidogrel administration did not lead to additional SAR264565-induced inhibition of platelet or fibrin deposition. CONCLUSION GPVI antagonism by the anti-GPVI-Fab fragment SAR264565 dose-dependently inhibits platelet adhesion and fibrin formation on a collagen surface under arterial shear. Additive inhibition is observed after prior aspirin administration with no further amplification on top of a combination of aspirin with clopidogrel. Ex vivo antiplatelet tests confirmed a selective inhibiting effect of SAR264565 on collagen-induced platelet activation.
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Affiliation(s)
- Peter Florian
- Sanofi-Aventis Deutschland GmbH, R&D, Industriepark Hoechst, Frankfurt am Main, Germany
| | - Peter Wonerow
- Sanofi-Aventis Deutschland GmbH, R&D, Industriepark Hoechst, Frankfurt am Main, Germany
| | - Sebastian Harder
- Pharmazentrum Frankfurt/ZAFES, Institute of Clinical Pharmacology, Johann Wolfgang Goethe University, Frankfurt/Main, Germany
| | - Karina Kuczka
- Pharmazentrum Frankfurt/ZAFES, Institute of Clinical Pharmacology, Johann Wolfgang Goethe University, Frankfurt/Main, Germany
| | - Michel Dubar
- Clinical Pharmacology and Exploratory Department, Sanofi-Aventis Recherche, Chilly-Mazarin, France
| | - Jochen Graff
- Pharmazentrum Frankfurt/ZAFES, Institute of Clinical Pharmacology, Johann Wolfgang Goethe University, Frankfurt/Main, Germany.
- Clinical Trial Centre Rhine-Main (KSRM) at the Pharmazentrum Frankfurt/ZAFES, Institute of Clinical Pharmacology, Johann Wolfgang Goethe University, Frankfurt/Main, Germany.
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Project Group Translational Medicine and Pharmacology TMP, Theodor-Stern-Kai 7, 60590, Frankfurt am Main, Germany.
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Van Aelst B, Feys HB, Devloo R, Vandekerckhove P, Compernolle V. Microfluidic Flow Chambers Using Reconstituted Blood to Model Hemostasis and Platelet Transfusion In Vitro. J Vis Exp 2016. [PMID: 27023054 DOI: 10.3791/53823] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Blood platelets prepared for transfusion gradually lose hemostatic function during storage. Platelet function can be investigated using a variety of (indirect) in vitro experiments, but none of these is as comprehensive as microfluidic flow chambers. In this protocol, the reconstitution of thrombocytopenic fresh blood with stored blood bank platelets is used to simulate platelet transfusion. Next, the reconstituted sample is perfused in microfluidic flow chambers which mimic hemostasis on exposed subendothelial matrix proteins. Effects of blood donation, transport, component separation, storage and pathogen inactivation can be measured in paired experimental designs. This allows reliable comparison of the impact every manipulation in blood component preparation has on hemostasis. Our results demonstrate the impact of temperature cycling, shear rates, platelet concentration and storage duration on platelet function. In conclusion, this protocol analyzes the function of blood bank platelets and this ultimately aids in optimization of the processing chain including phlebotomy, transport, component preparation, storage and transfusion.
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Affiliation(s)
| | - Hendrik B Feys
- Transfusion Research Center, Belgium Red Cross-Flanders;
| | | | - Philippe Vandekerckhove
- Blood Service, Belgium Red Cross-Flanders; Department of Public Health and Primary Care, Catholic University of Leuven; Faculty of Medicine and Health Sciences, University of Ghent
| | - Veerle Compernolle
- Transfusion Research Center, Belgium Red Cross-Flanders; Blood Service, Belgium Red Cross-Flanders; Faculty of Medicine and Health Sciences, University of Ghent
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Blair TA, Moore SF, Hers I. Circulating primers enhance platelet function and induce resistance to antiplatelet therapy. J Thromb Haemost 2015; 13:1479-93. [PMID: 26039631 PMCID: PMC4599128 DOI: 10.1111/jth.13022] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2015] [Accepted: 05/08/2015] [Indexed: 01/16/2023]
Abstract
BACKGROUND Aspirin and P2Y12 antagonists are antiplatelet compounds that are used clinically in patients with thrombosis. However, some patients are 'resistant' to antiplatelet therapy, which increases their risk of developing acute coronary syndromes. These patients often present with an underlying condition that is associated with altered levels of circulating platelet primers and platelet hyperactivity. Platelet primers cannot stimulate platelet activation, but, in combination with physiologic stimuli, significantly enhance platelet function. OBJECTIVES To explore the role of platelet primers in resistance to antiplatelet therapy, and to evaluate whether phosphoinositide 3-kinase (PI3K) contributes to this process. METHODS AND RESULTS We used platelet aggregation, thromboxane A2 production and ex vivo thrombus formation as functional readouts of platelet activity. Platelets were treated with the potent P2Y12 inhibitor AR-C66096, aspirin, or a combination of both, in the presence or absence of the platelet primers insulin-like growth factor-1 (IGF-1) and thrombopoietin (TPO), or the Gz-coupled receptor ligand epinephrine. We found that platelet primers largely overcame the inhibitory effects of antiplatelet compounds on platelet functional responses. IGF-1-mediated and TPO-mediated, but not epinephrine-mediated, enhancements in the presence of antiplatelet drugs were blocked by the PI3K inhibitors wortmannin and LY294002. CONCLUSIONS These results demonstrate that platelet primers can contribute to antiplatelet resistance. Furthermore, our data demonstrate that there are PI3K-dependent and PI3K-independent mechanisms driving primer-mediated resistance to antiplatelet therapy.
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Affiliation(s)
- T A Blair
- School of Physiology and Pharmacology, University of Bristol, Bristol, UK
| | - S F Moore
- School of Physiology and Pharmacology, University of Bristol, Bristol, UK
| | - I Hers
- School of Physiology and Pharmacology, University of Bristol, Bristol, UK
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Van Aelst B, Devloo R, Vandekerckhove P, Compernolle V, Feys HB. Ultraviolet C light pathogen inactivation treatment of platelet concentrates preserves integrin activation but affects thrombus formation kinetics on collagen in vitro. Transfusion 2015; 55:2404-14. [DOI: 10.1111/trf.13137] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Revised: 03/03/2015] [Accepted: 03/18/2015] [Indexed: 12/21/2022]
Affiliation(s)
- Britt Van Aelst
- Transfusion Research CenterBelgian Red Cross‐FlandersGhent Belgium
| | - Rosalie Devloo
- Transfusion Research CenterBelgian Red Cross‐FlandersGhent Belgium
| | - Philippe Vandekerckhove
- Blood Service of the Belgian Red Cross‐FlandersMechelen Belgium
- Department of Public Health and Primary CareCatholic University of LeuvenLeuven Belgium
- Faculty of Medicine and Health SciencesUniversity of GhentGhent Belgium
| | - Veerle Compernolle
- Transfusion Research CenterBelgian Red Cross‐FlandersGhent Belgium
- Blood Service of the Belgian Red Cross‐FlandersMechelen Belgium
- Faculty of Medicine and Health SciencesUniversity of GhentGhent Belgium
| | - Hendrik B. Feys
- Transfusion Research CenterBelgian Red Cross‐FlandersGhent Belgium
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Discovering anti-platelet drug combinations with an integrated model of activator-inhibitor relationships, activator-activator synergies and inhibitor-inhibitor synergies. PLoS Comput Biol 2015; 11:e1004119. [PMID: 25875950 PMCID: PMC4405222 DOI: 10.1371/journal.pcbi.1004119] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Accepted: 01/08/2015] [Indexed: 12/01/2022] Open
Abstract
Identifying effective therapeutic drug combinations that modulate complex
signaling pathways in platelets is central to the advancement of effective
anti-thrombotic therapies. However, there is no systems model of the platelet
that predicts responses to different inhibitor combinations. We developed an
approach which goes beyond current inhibitor-inhibitor combination screening to
efficiently consider other signaling aspects that may give insights into the
behaviour of the platelet as a system. We investigated combinations of platelet
inhibitors and activators. We evaluated three distinct strands of information,
namely: activator-inhibitor combination screens (testing a panel of inhibitors
against a panel of activators); inhibitor-inhibitor synergy screens; and
activator-activator synergy screens. We demonstrated how these analyses may be
efficiently performed, both experimentally and computationally, to identify
particular combinations of most interest. Robust tests of activator-activator
synergy and of inhibitor-inhibitor synergy required combinations to show
significant excesses over the double doses of each component. Modeling
identified multiple effects of an inhibitor of the P2Y12 ADP receptor, and
complementarity between inhibitor-inhibitor synergy effects and
activator-inhibitor combination effects. This approach accelerates the mapping
of combination effects of compounds to develop combinations that may be
therapeutically beneficial. We integrated the three information sources into a
unified model that predicted the benefits of a triple drug combination targeting
ADP, thromboxane and thrombin signaling. Drugs are often used in combinations, but establishing the best combinations is a
considerable challenge for basic and clinical research. Anti-platelet therapies
reduce thrombosis and heart attacks by lowering the activation of platelet
cells. We wanted to find good drug combinations, but a full systems model of the
platelet is absent, so we had no good predictions of how particular combinations
might behave. Instead, we put together three sources of knowledge. The first
concerned what inhibitors act on what activators; the second concerned what
pairs of activators synergise together (having a bigger effect than expected);
and the third concerned what pairs of inhibitors synergise together. We
implemented an efficient experimental approach to collect this information from
experiments on platelets. We developed a statistical model that brought these
separate results together. This gave us insights into how platelet inhibitors
act. For example, an inhibitor of an ADP receptor showed multiple effects. We
also worked out from the model what further (triple) combinations of drugs may
be most efficient. We predicted, and then tested experimentally, the effects of
a triple drug combination. This simultaneously inhibited the platelet’s
responses to three stimulants that it encounters during coronary thrombosis,
namely ADP, thromboxane and thrombin.
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Goto S, Hasebe T, Takagi S. Platelets: Small in Size But Essential in the Regulation of Vascular Homeostasis – Translation From Basic Science to Clinical Medicine –. Circ J 2015; 79:1871-81. [DOI: 10.1253/circj.cj-14-1434] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Shinya Goto
- Department of Medicine (Cardiology), Tokai University School of Medicine
- Department of Metabolic Disease Research Center, Tokai University Graduate School of Medicine
| | - Terumitsu Hasebe
- Department of Radiology, Tokai University Hachioji Hospital, Tokai University School of Medicine
| | - Shu Takagi
- Graduate School of Engineering, The University of Tokyo
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Van Aelst B, Feys HB, Devloo R, Vanhoorelbeke K, Vandekerckhove P, Compernolle V. Riboflavin and amotosalen photochemical treatments of platelet concentrates reduce thrombus formation kineticsin vitro. Vox Sang 2014; 108:328-39. [DOI: 10.1111/vox.12231] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Revised: 11/12/2014] [Accepted: 11/12/2014] [Indexed: 01/23/2023]
Affiliation(s)
- B. Van Aelst
- Transfusion Research Center; Belgian Red Cross-Flanders; Ghent Belgium
| | - H. B. Feys
- Transfusion Research Center; Belgian Red Cross-Flanders; Ghent Belgium
| | - R. Devloo
- Transfusion Research Center; Belgian Red Cross-Flanders; Ghent Belgium
| | - K. Vanhoorelbeke
- Laboratory for Thrombosis Research; KU Leuven Kulak; Kortrijk Belgium
| | - P. Vandekerckhove
- Blood Service of the Belgian Red Cross-Flanders; Mechelen Belgium
- Department of Public Health and Primary Care; Catholic University of Leuven; Leuven Belgium
| | - V. Compernolle
- Transfusion Research Center; Belgian Red Cross-Flanders; Ghent Belgium
- Blood Service of the Belgian Red Cross-Flanders; Mechelen Belgium
- Faculty of Medicine and Health Sciences; University of Ghent; Ghent Belgium
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Würtz M, Nissen PH, Grove EL, Kristensen SD, Hvas AM. Genetic determinants of on-aspirin platelet reactivity: focus on the influence of PEAR1. PLoS One 2014; 9:e111816. [PMID: 25360888 PMCID: PMC4216141 DOI: 10.1371/journal.pone.0111816] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Accepted: 10/08/2014] [Indexed: 12/18/2022] Open
Abstract
Background Platelet aggregation during aspirin treatment displays considerable inter-individual variability. A genetic etiology likely exists, but it remains unclear to what extent genetic polymorphisms determine platelet aggregation in aspirin-treated individuals. Aim To identify platelet-related single nucleotide polymorphisms (SNPs) influencing platelet aggregation during aspirin treatment. Furthermore, we explored to what extent changes in cyclooxygenase-1 activity and platelet activation may explain such influence. Methods We included 985 Danish patients with stable coronary artery disease treated with aspirin 75 mg/day mono antiplatelet therapy. Patients were genotyped for 16 common SNPs in platelet-related genes using standard PCR-based methods (TaqMan). Platelet aggregation was evaluated by whole blood platelet aggregometry employing Multiplate Analyzer (agonists: arachidonic acid and collagen) and VerifyNow Aspirin. Serum thromboxane B2 was measured to confirm aspirin adherence and was used as a marker of cyclooxygenase-1 activity. Soluble P-selectin was used as marker of platelet activation. Platelet aggregation, cyclooxygenase-1 activity, and platelet activation were compared across genotypes in adjusted analyses. Results The A-allele of the rs12041331 SNP in the platelet endothelial aggregation receptor-1 (PEAR1) gene was associated with reduced platelet aggregation and increased platelet activation, but not with cyclooxygenase-1 activity. Platelet aggregation was unaffected by the other SNPs analyzed. Conclusion A common genetic variant in PEAR1 (rs12041331) reproducibly influenced platelet aggregation in aspirin-treated patients with coronary artery disease. The exact biological mechanism remains elusive, but the effect of this polymorphism may be related to changes in platelet activation. Furthermore, 14 SNPs previously suggested to influence aspirin efficacy were not associated with on-aspirin platelet aggregation. Clinical Trial Registration ClinicalTrials.gov NCT01383304
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Affiliation(s)
- Morten Würtz
- Department of Cardiology, Aarhus University Hospital, Aarhus, Denmark
- Department of Internal Medicine, Regional Hospital West Jutland, Herning, Denmark
| | - Peter H. Nissen
- Department of Clinical Biochemistry, Aarhus University Hospital, Aarhus, Denmark
| | | | | | - Anne-Mette Hvas
- Department of Clinical Biochemistry, Aarhus University Hospital, Aarhus, Denmark
- * E-mail:
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Wang Y, Fang C, Gao H, Bilodeau ML, Zhang Z, Croce K, Liu S, Morooka T, Sakuma M, Nakajima K, Yoneda S, Shi C, Zidar D, Andre P, Stephens G, Silverstein RL, Hogg N, Schmaier AH, Simon DI. Platelet-derived S100 family member myeloid-related protein-14 regulates thrombosis. J Clin Invest 2014; 124:2160-71. [PMID: 24691441 DOI: 10.1172/jci70966] [Citation(s) in RCA: 103] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Accepted: 01/30/2014] [Indexed: 01/12/2023] Open
Abstract
Expression of the gene encoding the S100 calcium-modulated protein family member MRP-14 (also known as S100A9) is elevated in platelets from patients presenting with acute myocardial infarction (MI) compared with those from patients with stable coronary artery disease; however, a causal role for MRP-14 in acute coronary syndromes has not been established. Here, using multiple models of vascular injury, we found that time to arterial thrombotic occlusion was markedly prolonged in Mrp14⁻/⁻ mice. We observed that MRP-14 and MRP-8/MRP-14 heterodimers (S100A8/A9) are expressed in and secreted by platelets from WT mice and that thrombus formation was reduced in whole blood from Mrp14⁻/⁻ mice. Infusion of WT platelets, purified MRP-14, or purified MRP-8/MRP-14 heterodimers into Mrp14⁻/⁻ mice decreased the time to carotid artery occlusion after injury, indicating that platelet-derived MRP-14 directly regulates thrombosis. In contrast, infusion of purified MRP-14 into mice deficient for both MRP-14 and CD36 failed to reduce carotid occlusion times, indicating that CD36 is required for MRP-14-dependent thrombosis. Our data identify a molecular pathway of thrombosis that involves platelet MRP-14 and CD36 and suggest that targeting MRP-14 has potential for treating atherothrombotic disorders, including MI and stroke.
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Hosokawa K, Ohnishi T, Sameshima H, Miura N, Koide T, Maruyama I, Tanaka KA. Comparative evaluation of direct thrombin and factor Xa inhibitors with antiplatelet agents under flow and static conditions: an in vitro flow chamber model. PLoS One 2014; 9:e86491. [PMID: 24497951 PMCID: PMC3908954 DOI: 10.1371/journal.pone.0086491] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Accepted: 12/10/2013] [Indexed: 12/29/2022] Open
Abstract
Dabigatran and rivaroxaban are novel oral anticoagulants that specifically inhibit thrombin and factor Xa, respectively. The aim of this study is to elucidate antithrombotic properties of these anticoagulant agents under arterial and venous shear conditions. Whole blood samples treated with dabigatran or rivaroxaban at 250, 500, and 1000 nM, with/without aspirin and AR-C66096, a P2Y12 antagonist, were perfused over a microchip coated with collagen and tissue thromboplastin at shear rates of 240 and 600 s(-1). Fibrin-rich platelet thrombus formation was quantified by monitoring flow pressure changes. Dabigatran at higher concentrations (500 and 1000 nM) potently inhibited thrombus formation at both shear rates, whereas 1000 nM of rivaroxaban delayed, but did not completely inhibit, thrombus formation. Dual antiplatelet agents weakly suppressed thrombus formation at both shear rates, but intensified the anticoagulant effects of dabigatran and rivaroxaban. The anticoagulant effects of dabigatran and rivaroxaban were also evaluated under static conditions using thrombin generation (TG) assay. In platelet-poor plasma, dabigatran at 250 and 500 nM efficiently prolonged the lag time (LT) and moderately reduce peak height (PH) of TG, whereas rivaroxaban at 250 nM efficiently prolonged LT and reduced PH of TG. In platelet-rich plasma, however, both anticoagulants efficiently delayed LT and reduced PH of TG. Our results suggest that dabigatran and rivaroxaban may exert distinct antithrombotic effects under flow conditions, particularly in combination with dual antiplatelet therapy.
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Affiliation(s)
- Kazuya Hosokawa
- Research Institute, Fujimori Kogyo Co., Yokohama, Kanagawa, Japan
- Department of System Biology in Thromboregulation, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Tomoko Ohnishi
- Research Institute, Fujimori Kogyo Co., Yokohama, Kanagawa, Japan
| | - Hisayo Sameshima
- Research Institute, Fujimori Kogyo Co., Yokohama, Kanagawa, Japan
| | - Naoki Miura
- Joint Faculty of Veterinary Medicine, Kagoshima University, Kagoshima, Japan
| | - Takehiko Koide
- Department of System Biology in Thromboregulation, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Ikuro Maruyama
- Department of System Biology in Thromboregulation, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Kenichi A. Tanaka
- Department of Anesthesiology, Vascular Medicine Institute, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
- * E-mail:
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15
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Morgan DR, Arrow J, Smith MP. Combining aspirin with cholecalciferol (vitamin D3)--a potential new tool for controlling possum populations. PLoS One 2013; 8:e70683. [PMID: 23950982 PMCID: PMC3739777 DOI: 10.1371/journal.pone.0070683] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Accepted: 06/21/2013] [Indexed: 11/18/2022] Open
Abstract
The introduced Australian brushtail possum is a major vertebrate pest in New Zealand, with impacts on conservation and agriculture being managed largely through poisoning operations. Cholecalciferol (vitamin D3) is registered for use in controlling possums and despite its many advantages it is expensive and relatively inhumane. Combination of a high proportion of aspirin with a low proportion of cholecalciferol was effective in killing high proportions of groups of acclimatised, caged possums: this is attributed to both an unexpectedly high toxicity of the type of cholecalciferol used, and a proposed synergistic mechanism between the two compounds. Death was caused by localised damage to heart ventricles by aspirin, and inhibition of tissue repair by both aspirin and cholecalciferol. The observed toxicosis had lower impact on the welfare of possums than either compound administered alone, particularly aspirin alone. Residue analyses of bait remains in the GI tract suggested a low risk of secondary poisoning by either compound. The combination of cholecalciferol and aspirin has the potential to meet key requirements of cost-effectiveness and humaneness in controlling possum populations, but the effect of the combination in non-target species has yet to be tested.
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Purinergic mechanisms and pain--an update. Eur J Pharmacol 2013; 716:24-40. [PMID: 23524093 DOI: 10.1016/j.ejphar.2013.01.078] [Citation(s) in RCA: 94] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2012] [Revised: 12/11/2012] [Accepted: 01/09/2013] [Indexed: 12/12/2022]
Abstract
There is a brief summary of the background literature about purinergic signalling. The review then considers purinergic mechanosensory transduction involved in visceral, cutaneous and musculoskeletal nociception and on the roles played by P2X3, P2X2/3, P2X4, P2X7 and P2Y₁₂ receptors in neuropathic and inflammatory pain. Current developments of compounds for the therapeutic treatment of both visceral and neuropathic pain are discussed.
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Keinan D, Leigh NJ, Nelson JW, De Oleo L, Baker OJ. Understanding resolvin signaling pathways to improve oral health. Int J Mol Sci 2013; 14:5501-18. [PMID: 23528855 PMCID: PMC3634469 DOI: 10.3390/ijms14035501] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2012] [Revised: 02/19/2013] [Accepted: 02/22/2013] [Indexed: 12/15/2022] Open
Abstract
The discovery of resolvins has been a major breakthrough for understanding the processes involved in resolution of inflammation. Resolvins belong to a family of novel lipid mediators that possess dual anti-inflammatory and pro-resolution actions. Specifically, they protect healthy tissue during immune-inflammatory responses to infection or injury, thereby aiding inflammation resolution and promoting tissue healing. One of the major concerns in modern medicine is the management and treatment of oral diseases, as they are related to systemic outcomes impacting the quality of life of many patients. This review summarizes known signaling pathways utilized by resolvins to regulate inflammatory responses associated with the oral cavity.
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Affiliation(s)
- David Keinan
- Department of Periodontics and Endodontics, School of Dental Medicine, University at Buffalo, the State University of New York, Buffalo, NY 14214-3932, USA; E-Mail:
- Department of Oral Biology, School of Dental Medicine, University at Buffalo, the State University of New York, Buffalo, NY 14214-3932, USA; E-Mails: (N.J.L.); (J.W.N.); (L.D.O.)
| | - Noel J. Leigh
- Department of Oral Biology, School of Dental Medicine, University at Buffalo, the State University of New York, Buffalo, NY 14214-3932, USA; E-Mails: (N.J.L.); (J.W.N.); (L.D.O.)
| | - Joel W. Nelson
- Department of Oral Biology, School of Dental Medicine, University at Buffalo, the State University of New York, Buffalo, NY 14214-3932, USA; E-Mails: (N.J.L.); (J.W.N.); (L.D.O.)
| | - Laura De Oleo
- Department of Oral Biology, School of Dental Medicine, University at Buffalo, the State University of New York, Buffalo, NY 14214-3932, USA; E-Mails: (N.J.L.); (J.W.N.); (L.D.O.)
| | - Olga J. Baker
- Department of Oral Biology, School of Dental Medicine, University at Buffalo, the State University of New York, Buffalo, NY 14214-3932, USA; E-Mails: (N.J.L.); (J.W.N.); (L.D.O.)
- To whom correspondence should be addressed; E-Mail: ; Tel.: +1-716-829-3667; Fax: +1-716-829-3942
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Abstract
Because novel direct acting anticoagulants are being tested in the secondary prevention of cardiovascular events, we assessed potential effects of a direct acting antagonist of Factor Xa on platelet function. Blood from patients with known coronary artery disease who were treated with aspirin but no other antithrombotic agent was spiked in vitro with rivaroxaban alone or in combination with a direct acting P2Y12 antagonist (cangrelor). To limit cofounding effects of anticoagulants and to enable interaction between coagulation factors, blood was anticoagulated only with a specific inhibitor of Factor XIIa, corn trypsin inhibitor. Polymerization of fibrin was prevented with the peptide GPRP. Activation of platelets was determined with the use of flow cytometry in response to lipidated tissue factor, thrombin, the collagen mimetic convulxin, and adenosine diphosphate (ADP). Rivaroxaban inhibited the activation of platelets induced by tissue factor and to a lesser extent activation induced by thrombin, effects that were accentuated when combined with cangrelor. Rivaroxaban did not attenuate convulxin-induced activation of platelets; however, a limited but consistent attenuation of ADP-induced platelet activation was seen with blood anticoagulated with rivaroxaban. Effects of rivaroxaban on ADP-induced platelet activation were not mediated by thrombin, tissue factor, or platelet-leukocyte aggregation. In conclusion, rivaroxaban attenuated in vitro the activation of platelets mediated by thrombin. In light of the pivotal role of thrombin in platelet activation after rupture of an atherosclerotic plaque, rivaroxaban should attenuate platelet activation in vivo, an effect that is accentuated by combination with a P2Y12 antagonist.
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Tarandovskiy ID, Artemenko EO, Panteleev MA, Sinauridze EI, Ataullakhanov FI. Antiplatelet agents can promote two-peaked thrombin generation in platelet rich plasma: mechanism and possible applications. PLoS One 2013; 8:e55688. [PMID: 23405196 PMCID: PMC3566002 DOI: 10.1371/journal.pone.0055688] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Accepted: 01/02/2013] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Thrombin generation assay is a convenient and widely used method for analysis of the blood coagulation system status. Thrombin generation curve (TGC) is usually bell-shaped with a single peak, but there are exceptions. In particular, TGC in platelet-rich plasma (PRP) can sometimes have two peaks. OBJECTIVE We sought to understand the mechanism underlying the occurrence of two peaks in the PRP thrombin generation curve. METHODS Tissue factor-induced thrombin generation in PRP and platelet-poor plasma (PPP) was monitored using continuous measurement of the hydrolysis rate of the thrombin-specific fluorogenic substrate Z-Gly-Gly-Arg-AMC. Expression of phosphatidylserine (PS) and CD62P on the surface of activated platelets was measured by flow cytometry using corresponding fluorescently labeled markers. RESULTS The addition of the P(2)Y(12) receptor antagonist MeS-AMP (160 µM), 83 nM prostaglandin E(1) (PGE(1)), or 1.6% DMSO to PRP caused the appearance of two peaks in the TGC. The PS exposure after thrombin activation on washed platelets in a suspension supplemented with DMSO, PGE(1) or MeS-AMP was delayed, which could indicate mechanism of the second peak formation. Supplementation of PRP with 1.6% DMSO plus 830 nM PGE(1) mediated the disappearance of the second peak and decreased the amplitude of the first peak. Increasing the platelet concentration in the PRP promoted the consolidation of the two peaks into one. CONCLUSIONS Procoagulant tenase and prothrombinase complexes in PRP assemble on phospholipid surfaces containing PS of two types--plasma lipoproteins and the surface of activated platelets. Thrombin generation in the PRP can be two-peaked. The second peak appears in the presence of platelet antagonists as a result of delayed PS expression on platelets, which leads to delayed assembly of the membrane-dependent procoagulant complexes and a second wave of thrombin generation.
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Affiliation(s)
- Ivan D Tarandovskiy
- The Laboratory of the Molecular Mechanisms of Hemostasis, the Center for Theoretical Problems of Physicochemical Pharmacology RAS, Moscow, Russia.
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Heparin rescues factor V Leiden-associated placental failure independent of anticoagulation in a murine high-risk pregnancy model. Blood 2013; 121:2127-34. [PMID: 23325830 DOI: 10.1182/blood-2012-08-448209] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Low molecular weight heparin (LMWH) is being tested as an experimental drug for improving pregnancy outcome in women with inherited thrombophilia and placenta-mediated pregnancy complications, such as recurrent pregnancy loss. The role of thrombotic processes in these disorders remains unproven, and the issue of antithrombotic prophylaxis is intensely debated. Using a murine model of factor V Leiden-associated placental failure, we show that treatment of the mother with LMWH allows placental development to proceed and affords significant protection from fetal loss. Nonetheless, the therapeutic effect of LMWH is not replicated by anticoagulation; fondaparinux and a direct Xa inhibitor, C921-78, achieve anticoagulation similar to LMWH but produce little or no improvement in pregnancy outcome. Genetic attenuation of maternal platelet aggregation is similarly ineffective. In contrast, even a partial loss of thrombin sensitivity of maternal platelets protects pregnancies. Neonates born from these pregnancies are growth retarded, suggesting that placental function is only partially restored. The placentae are smaller but do not reveal any evidence of thrombosis. Our data demonstrate an anticoagulation-independent role of LMWH in protecting pregnancies and provide evidence against the involvement of thrombotic processes in thrombophilia-associated placental failure. Importantly, thrombin-mediated maternal platelet activation remains central in the mechanism of placental failure.
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Van Kruchten R, Cosemans JMEM, Heemskerk JWM. Measurement of whole blood thrombus formation using parallel-plate flow chambers - a practical guide. Platelets 2012; 23:229-42. [PMID: 22502645 DOI: 10.3109/09537104.2011.630848] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Custom-made and commercial parallel-plate flow chambers are widely used for studies of platelet activation and thrombus formation in whole blood at defined shear rates. When used in a reproducible way, such flow chamber devices give valuable information on the thrombogenic potential of human, mouse, or rat blood. This article aims to provide a practical guide for the use of parallel-plate flow chambers in combination with routine microscopic imaging techniques. The following methodological aspects are addressed: preparation of surface coatings, calculation of blood flow and shear rate, control of pre-analytical variables, protocols for routine performing of flow chamber tests with non-coagulating or coagulating blood, and procedures for real-time and end-point analysis of thrombus formation. Frequently encountered experimental problems and artifacts are discussed, as well as possibilities for using flow chamber devices as a diagnostic tool to test antithrombotic medication.
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Affiliation(s)
- Roger Van Kruchten
- Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, The Netherlands
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22
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Labarthe B, Babin J, Bryckaert M, Théroux P, Bonnefoy A. Effects of P2Y(1) receptor antagonism on the reactivity of platelets from patients with stable coronary artery disease using aspirin and clopidogrel. Br J Pharmacol 2012; 166:221-31. [PMID: 21950486 DOI: 10.1111/j.1476-5381.2011.01683.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND AND PURPOSE P2Y(1) is a purine receptor that triggers platelet aggregation. Its inhibition was studied in patients with stable coronary artery disease (CAD) receiving standard anti-platelet therapy. EXPERIMENTAL APPROACH Blood samples from 10 patients on aspirin therapy (ASA, 80 mg·day(-1) ) were withdrawn before and 24 h after the administration of 450 mg clopidogrel (ASA/C) and were anti-coagulated with citrate or hirudin/PPACK in the presence or absence of the P2Y(1 ) inhibitor MRS2179 (M, 100 µM). Platelet responses to ADP (2.5 µM) and TRAP (2.5 µM), and collagen-induced thrombosis under flow conditions were analysed. KEY RESULTS Compared with ASA, ASA + M strongly inhibited ADP-induced peak platelet aggregation (88%), late aggregation (84%), P-selectin expression (85%) and α(IIb) β(3) activation (62%) (28%, 65%, 70% and 51% inhibition, respectively, for ASA/C vs. ASA). ASA + M also inhibited platelet/monocyte and platelet/neutrophil conjugate formation by 69% and 71% (57% and 59% for ASA/C vs. ASA). In TRAP-activated blood, ASA + M unexpectedly inhibited α(IIb) b(3) activation by 30%. In blood perfused in collagen-coated glass capillaries (shear rate of 1500 s(-1) ), ASA/C prevented thrombus growth beyond 5 min in relation to thrombus fragments embolization. ASA + M with or without clopidogrel completely prevented thrombus formation. Finally, ex vivo addition of MRS2179 and ASA to the blood of healthy donors markedly blocked thrombus formation on collagen in flow conditions, in contrast to ASA plus the P2Y(12) inhibitor 2-MeSAMP. CONCLUSIONS AND IMPLICATIONS Through particularly efficient complementarities with ASA to inhibit platelet activation and thrombus formation, the inhibition of P2Y(1) in the blood of patients with CAD appears to play a more important role than previously anticipated.
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Affiliation(s)
- B Labarthe
- Department of Medicine, Montreal Heart Institute, Montreal, Quebec, Canada
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23
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Stephens G, He M, Wong C, Jurek M, Luedemann HC, Shapurian G, Munnelly K, Muir C, Conley PB, Phillips DR, Andre P. Development of a perfusion chamber assay to study in real time the kinetics of thrombosis and the antithrombotic characteristics of antiplatelet drugs. Thromb J 2012; 10:11. [PMID: 22852789 PMCID: PMC3502277 DOI: 10.1186/1477-9560-10-11] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Accepted: 07/18/2012] [Indexed: 11/13/2022] Open
Abstract
Background Arterial thrombosis triggered by vascular injury is a balance between thrombus growth and thrombus fragmentation (dethrombosis). Unbalance towards thrombus growth can lead to vascular occlusion, downstream ischemia and tissue damage. Here we describe the development of a simple methodology that allows for continuous real time monitoring and quantification of both processes during perfusion of human blood under arterial shear rate conditions. Using this methodology, we have studied the effects of antiplatelet agents targeting COX-1 (aspirin), P2Y12 (2-MeSAMP, clopidogrel), GP IIb-IIIa (eptifibatide) and their combinations on the kinetics of thrombosis over time. Results Untreated samples of blood perfused over type III collagen at arterial rates of shear promoted the growth of stable thrombi. Modulation by eptifibatide affected thrombus growth, while that mediated by 2-MeSAMP and aspirin affected thrombus stability. Using this technique, we confirmed the primacy of continuous signaling by the ADP autocrine loop acting on P2Y12 in the maintenance of thrombus stability. Analysis of the kinetics of thrombosis revealed that continuous and prolonged analysis of thrombosis is required to capture the role of platelet signaling pathways in their entirety. Furthermore, studies evaluating the thrombotic profiles of 20 healthy volunteers treated with aspirin, clopidogrel or their combination indicated that while three individuals did not benefits from either aspirin or clopidogrel treatments, all individuals displayed marked destabilization profiles when treated with the combination regimen. Conclusions These results show the utility of a simple perfusion chamber technology to assess in real time the activity of antiplatelet drugs and their combinations. It offers the opportunity to perform pharmacodynamic monitoring of arterial thrombosis in clinical trials and to investigate novel strategies directed at inhibiting thrombus stability in the management of cardiovascular disease.
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Affiliation(s)
- Gillian Stephens
- Portola Pharmaceuticals Inc, 270 E, Grand Avenue, Ste 22, South San Francisco, CA 94080, USA.
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24
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Hosokawa K, Ohnishi T, Kondo T, Fukasawa M, Koide T, Maruyama I, Tanaka KA. A novel automated microchip flow-chamber system to quantitatively evaluate thrombus formation and antithrombotic agents under blood flow conditions. J Thromb Haemost 2011; 9:2029-37. [PMID: 21827607 DOI: 10.1111/j.1538-7836.2011.04464.x] [Citation(s) in RCA: 112] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND AND AIMS In the present study, we describe a newly developed microchip-based analytical system to evaluate white thrombus formation (WTF). Efficacies of various antithrombotic agents were compared under different flow conditions. METHODS Whole blood containing corn trypsin inhibitor was perfused over a microchip coated with collagen and tissue thromboplastin at the lower and higher shear rates of 240 and 600 s(-1) , and WTF process inside the microchip was quantified by monitoring a flow pressure. Parameters of T(10) (time to 10 kPa), T(10-80) (time from 10 to 80 kPa) and OT (occlusion time; time to 80 kPa) were used to evaluate the onset and the growth rate of WTF, and the capillary occlusion, respectively. RESULTS After perfusion was started, white thrombus composed of activated platelets and fibrin was formed on the coated surface. Thrombus gradually increased in size and eventually occluded the capillary. Among anticoagulants, heparin (0.5-1.0 U mL(-1)) potently prolonged T(10) at both shear rates, whereas low molecular weight heparin (1.0-2.0 IU mL(-1)) inhibited the growth of WTF at the lower shear rate. Among antiplatelet agents, abciximab (1-2 μg mL(-1)) significantly reduced the size and number of thrombi, which was additively enhanced in the presence of heparin (0.5 U mL(-1) ). OS-1 (specific GPIbα-antagonist) prevented the complete capillary occlusion. CONCLUSION The novel monitoring system of WTF may be useful in preclinical and clinical evaluations of different types of antithrombotic strategies, and their effects in combination.
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Affiliation(s)
- K Hosokawa
- Research Institute, Fujimori Kogyo Co., Yokohama, Kanagawa, Japan
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25
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Théorêt JF, Yacoub D, Hachem A, Gillis MA, Merhi Y. P-selectin ligation induces platelet activation and enhances microaggregate and thrombus formation. Thromb Res 2011; 128:243-50. [DOI: 10.1016/j.thromres.2011.04.018] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2011] [Revised: 03/24/2011] [Accepted: 04/25/2011] [Indexed: 11/27/2022]
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Does Platelet Function Testing Predict Bleeding?-Con. POINT OF CARE 2011. [DOI: 10.1097/poc.0b013e318228bea1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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27
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Abstract
Although current antiplatelet therapies provide potent antithrombotic effects, their efficacy is limited by a heightened risk of bleeding and failure to affect vascular remodeling after injury. New lines of research suggest that thrombosis and hemorrhage may be uncoupled at the interface of pathways controlling thrombosis and inflammation. Here, as one remarkable example, studies using a novel and highly selective pharmacologic inhibitor of the spleen tyrosine kinase Syk [PRT060318; 2-((1R,2S)-2-aminocyclohexylamino)-4-(m-tolylamino)pyrimidine-5-carboxamide] coupled with genetic experiments, demonstrate that Syk inhibition ameliorates both the acute and chronic responses to vascular injury without affecting hemostasis. Specifically, lack of Syk (murine radiation chimeras) attenuated shear-induced thrombus formation ex vivo, and PRT060318 strongly inhibited arterial thrombosis in vivo in multiple animal species while having minimal impact on bleeding. Furthermore, leukocyte-platelet-dependent responses to vascular injury, including inflammatory cell recruitment and neointima formation, were markedly inhibited by PRT060318. Thus, Syk controls acute and long-term responses to arterial vascular injury. The therapeutic potential of Syk may be exemplary of a new class of antiatherothrombotic agents that target the interface between thrombosis and inflammation.
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28
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Haberstock-Debic H, Andre P, Mills S, Phillips DR, Conley PB. A clopidogrel-insensitive inducible pool of P2Y12 receptors contributes to thrombus formation: inhibition by elinogrel, a direct-acting, reversible P2Y12 antagonist. J Pharmacol Exp Ther 2011; 339:54-61. [PMID: 21730013 DOI: 10.1124/jpet.111.184143] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
It is known that hepatic metabolism limits the antiaggregatory activity of clopidogrel and, as a consequence, its clinical benefits. In this study, we investigated whether other factors exist that could account for clopidogrel's suboptimal antithrombotic activity. Using an in vivo murine FeCl(3) thrombosis model coupled with intravital microscopy, we found that at equivalent, maximal levels of inhibition of ADP-induced platelet aggregation, clopidogrel (50 mg/kg p.o.) failed to reproduce the phenotype associated with P2Y(12) deficiency. However, elinogrel (60 mg/kg p.o.), a direct-acting reversible P2Y(12) antagonist, achieved maximal levels of inhibition in vivo, and its administration (1 mg/kg i.v.) abolished residual thrombosis associated with clopidogrel dosing. Because elinogrel is constantly present in the plasma, whereas the active metabolite of clopidogrel exists for ∼2 h, we evaluated whether an intracellular pool of P2Y(12) exists that would be inaccessible to clopidogrel and contribute to its limited antithrombotic activity. Using saturation [(3)H]2-(methylthio)ADP ([(3)H]2MeSADP) binding studies, we first demonstrated that platelet stimulation with thrombin and convulxin (mouse) and thrombin receptor activating peptide (TRAP) (human) significantly increased surface expression of P2Y(12) relative to that of resting platelets. We next found that clopidogrel dose-dependently inhibited ADP-induced aggregation, signaling (cAMP), and surface P2Y(12) on resting mouse platelets, achieving complete inhibition at the highest dose (50 mg/kg), but failed to block this inducible pool. Thus, an inducible pool of P2Y(12) exists on platelets that can be exposed upon platelet activation by strong agonists. This inducible pool is not blocked completely by clopidogrel, contributes to thrombosis in vivo, and can be blocked by elinogrel.
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Affiliation(s)
- Helena Haberstock-Debic
- Portola Pharmaceuticals Inc, 270 East Grand Avenue, South San Francisco, California 94080, USA
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29
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André P, DeGuzman F, Haberstock-Debic H, Mills S, Pak Y, Inagaki M, Pandey A, Hollenbach S, Phillips DR, Conley PB. Thienopyridines, but Not Elinogrel, Result in Off-Target Effects at the Vessel Wall That Contribute to Bleeding. J Pharmacol Exp Ther 2011; 338:22-30. [DOI: 10.1124/jpet.110.178574] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
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Golański J, Michalska M, Polowinczak-Przybyłek J, Krajewska U, Watała C. Can we extrapolate the outcomes of in vitro studies on murine endothelium to studies of human platelet-endothelium interactions? A technical note. Arch Med Sci 2011; 7:34-7. [PMID: 22291730 PMCID: PMC3258691 DOI: 10.5114/aoms.2011.20601] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2009] [Revised: 08/30/2009] [Accepted: 09/21/2009] [Indexed: 11/17/2022] Open
Abstract
INTRODUCTION Interactions between vascular endothelium and blood platelets play a crucial role in cardiovascular diseases. Ex vitro models which use endothelial cells and platelets were the essential tools to investigate these interactions and their impact on haemostasis. The impaired interplay between vascular endothelium, blood platelets and leukocytes is believed to contribute to the development of cardiovascular disease. In this study we compared the ability of human (HUVECs) and murine (HECa10) endothelial cells to inhibit human platelet function and reactivity under in vitro conditions. MATERIAL AND METHODS The aliquots of platelet-rich plasma obtained from 20 healthy donors were incubated with murine endothelial cell line HECa10 or human umbilical vein endothelial cells (HUVECs) (10 min, 37°C) prior to agonizing platelets with 5 µM ADP and monitoring platelet reactivity for 10 min using optical aggregation. RESULTS Significant reduction in ADP-induced platelet aggregation in the presence of endothelial cell cultures remained independent of cell count. HUVECs appeared much more effective in the inhibition of platelet aggregation compared to HECa10 (35.2 ±2.3 AU vs. 43.7 ±2.0 AU, p= 0.025). CONCLUSIONS HECa10 cells have much lower potential to inhibit platelet aggregation than HUVECs. This implies that these two cell lines may not be freely used interchangeably in in vitro experiments. These findings clearly indicate that the outcomes of in vitro studies performed with murine EC lines cannot be unreservedly extrapolated to human platelet-endothelium interactions.
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Affiliation(s)
- Jacek Golański
- Department of Haemostasis and Haemostatic Disorders, Medical University of Lodz, Poland
| | - Marta Michalska
- Department of Hypertension, Medical University of Lodz, Poland
| | | | - Urszula Krajewska
- Molecular Biology Laboratory, Department of Pharmaceutical Biochemistry, Medical University of Lodz, Poland
| | - Cezary Watała
- Department of Haemostasis and Haemostatic Disorders, Medical University of Lodz, Poland
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31
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Mendolicchio GL, Zavalloni D, Bacci M, Corrada E, Marconi M, Lodigiani C, Presbitero P, Rota L, Ruggeri ZM. Variable effect of P2Y12 inhibition on platelet thrombus volume in flowing blood. J Thromb Haemost 2011; 9:373-82. [PMID: 21083646 PMCID: PMC3030676 DOI: 10.1111/j.1538-7836.2010.04144.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
BACKGROUND AND OBJECTIVES Patients treated with percutaneous coronary intervention receive aspirin and P2Y12 ADP receptor inhibitors to reduce thrombotic complications. The choice of methodology for monitoring the effects of treatment and assessing its efficacy is still a topic of debate. We evaluated how decreased P2Y12 function influences platelet aggregate (thrombus) size measured ex vivo. METHODS AND RESULTS We used confocal videomicroscopy to measure in real time the volume of platelet thrombi forming upon blood perfusion over fibrillar collagen type I at a wall shear rate of 1500 s(-1). The average volume was significantly smaller in 31 patients receiving aspirin and clopidogrel (19) or ticlopidine (12) than in 21 controls, but individual values were above the lower limit of the normal distribution, albeit mostly within the lower quartile, in 61.3% of cases. Disaggregation of platelet thrombi at later perfusion times occurred frequently in the patients. Vasodilator-stimulated phosphoprotein phosphorylation, reflecting P2Y12 inhibition, was also decreased in the patient group, and only 22.6% of individual values were above the lower normal limit. We found no correlation between volume of thrombus formed on collagen fibrils and level of P2Y12 inhibition, suggesting that additional and individually variable factors can influence the inhibitory effect of treatment on platelet function. CONCLUSIONS Measurements of platelet thrombus formation in flowing blood reflects the consequences of antiplatelet therapy in a manner that is not proportional to P2Y12 inhibition. Combining the results of the two assays may improve the assessment of thrombotic risk.
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Affiliation(s)
- G L Mendolicchio
- Thrombosis Center, IRCCS Istituto Clinico Humanitas, Rozzano, Milan, Italy.
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32
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Roles and interactions among protease-activated receptors and P2ry12 in hemostasis and thrombosis. Proc Natl Acad Sci U S A 2010; 107:18605-10. [PMID: 20930120 DOI: 10.1073/pnas.1013309107] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Toward understanding their redundancies and interactions in hemostasis and thrombosis, we examined the roles of thrombin receptors (protease-activated receptors, PARs) and the ADP receptor P2RY12 (purinergic receptor P2Y G protein-coupled 12) in human and mouse platelets ex vivo and in mouse models. Par3(-/-) and Par4(+/-) mouse platelets showed partially decreased responses to thrombin, resembling those in PAR1 antagonist-treated human platelets. P2ry12(+/-) mouse platelets showed partially decreased responses to ADP, resembling those in clopidogrel-treated human platelets. Par3(-/-) mice showed nearly complete protection against carotid artery thrombosis caused by low FeCl(3) injury. Par4(+/-) and P2ry12(+/-) mice showed partial protection. Increasing FeCl(3) injury abolished such protection; combining partial attenuation of thrombin and ADP signaling, as in Par3(-/-):P2ry12(+/-) mice, restored it. Par4(-/-) mice, which lack platelet thrombin responses, showed still better protection. Our data suggest that (i) the level of thrombin driving platelet activation and carotid thrombosis was low at low levels of arterial injury and increased along with the contribution of thrombin-independent pathways of platelet activation with increasing levels of injury; (ii) although P2ry12 acts downstream of PARs to amplify platelet responses to thrombin ex vivo, P2ry12 functioned in thrombin/PAR-independent pathways in our in vivo models; and (iii) P2ry12 signaling was more important than PAR signaling in hemostasis models; the converse was noted for arterial thrombosis models. These results make predictions being tested by ongoing human trials and suggest hypotheses for new antithrombotic strategies.
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Streamlining the design of promising clinical trials: in-vitro testing of antithrombotic regimens and multiple agonists of platelet activation. Coron Artery Dis 2009; 20:175-8. [PMID: 19194284 DOI: 10.1097/mca.0b013e32831edcd1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Platelets are activated in vivo by multiple agonists; however, platelet function testing in vitro has been performed predominantly with only one or two agonists of platelet activation. Greater insight into anticipated effects of antithrombotic regimens should enhance the design of successful clinical trials. To test this concept, we assessed platelet activation induced by multiple agonists and two antithrombotic regimens, unfractionated heparin (UFH) and eptifibatide compared with bivalirudin and cangrelor. Blood samples from 10 patients with coronary artery disease were spiked with pharmacologic concentrations achieved in vivo of either UFH (1.2 U/ml) and eptifibatide (1.7 microg/ml), or with bivalirudin (8 microg/ml) and cangrelor (500 nmol/l). Platelet function was assessed with the use of flow cytometry. Agonists included thrombin (50 nmol/l), adenosine diphosphate (1 micromol/l), the collagen-mimetic convulxin (5 ng/ml), and platelet-activating factor (10 nmol/l). When platelet activation was identified by the surface expression of P-selectin in response to multiple agonists, the combination of bivalirudin and cangrelor suppressed activation more than UFH and eptifibatide. When platelet activation was identified by the activation of glycoprotein IIb-IIIa (PAC-1 binding), the combination of bivalirudin and cangrelor was more effective in suppressing activation in response to thrombin and adenosine diphosphate, whereas UFH and eptifibatide more effectively prevented binding of PAC-1 when platelets were activated with the collagen-mimetic convulxin. In conclusion, bivalirudin and cangrelor suppressed platelet activation in response to diverse agonists in vitro more than UFH and eptifibatide. These results and this approach to selection of promising interventions should be helpful in streamlining the design of clinical trials.
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Becker RC, Moliterno DJ, Jennings LK, Pieper KS, Pei J, Niederman A, Ziada KM, Berman G, Strony J, Joseph D, Mahaffey KW, Van de Werf F, Veltri E, Harrington RA. Safety and tolerability of SCH 530348 in patients undergoing non-urgent percutaneous coronary intervention: a randomised, double-blind, placebo-controlled phase II study. Lancet 2009; 373:919-28. [PMID: 19286091 DOI: 10.1016/s0140-6736(09)60230-0] [Citation(s) in RCA: 206] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
BACKGROUND An antithrombotic drug is needed that safely reduces cardiovascular events in patients undergoing percutaneous coronary intervention (PCI). We therefore assessed the tolerability and safety of SCH 530348-an oral platelet protease-activated receptor-1 antagonist. METHODS We randomly assigned patients aged 45 years or older and undergoing non-urgent PCI or coronary angiography with planned PCI to an oral loading dose of SCH 530348 (10 mg, 20 mg, or 40 mg) or matching placebo in a 3:1 ratio in a multicentre international study. Those in the SCH 530348 group who subsequently underwent PCI (primary PCI cohort) continued taking an oral maintenance dose (0.5 mg, 1.0 mg, or 2.5 mg per day), and patients in the placebo group continued placebo for 60 days. The primary endpoint was the incidence of clinically significant major or minor bleeding according to the thrombolysis in myocardial infarction (TIMI) scale. Both investigators and patients were unaware of treatment allocation. Analysis was by intention to treat. This study is registered with ClinicalTrials.gov, number NCT00132912. FINDINGS 257 patients were assigned to placebo and 773 to SCH 530348. The primary endpoint occurred in 2 (2%) of 129, 3 (3%) of 120, and 7 (4%) of 173 patients, respectively, in the SCH 530348 10 mg, 20 mg, and 40 mg groups compared with 5 (3%) of 151 patients in the placebo group (p=0.5786). TIMI major plus minor bleeding occurred in 3 (2%) of 136, 5 (4%) of 139, and 4 (3%) of 138 patients given SCH 530348 0.5 mg, 1.0 mg, and 2.5 mg once per day, respectively (p=0.7561). INTERPRETATION Oral SCH 530348 was generally well tolerated and did not cause increased TIMI bleeding, even when administered concomitantly with aspirin and clopidogrel. Further testing in phase III trials to accurately define the safety and efficacy of SCH 530348 is warranted.
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Gori AM, Marcucci R, Migliorini A, Valenti R, Moschi G, Paniccia R, Buonamici P, Gensini GF, Vergara R, Abbate R, Antoniucci D. Incidence and clinical impact of dual nonresponsiveness to aspirin and clopidogrel in patients with drug-eluting stents. J Am Coll Cardiol 2008; 52:734-9. [PMID: 18718420 DOI: 10.1016/j.jacc.2008.05.032] [Citation(s) in RCA: 147] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2008] [Revised: 05/05/2008] [Accepted: 05/06/2008] [Indexed: 01/28/2023]
Abstract
OBJECTIVES This study sought to determine the incidence of aspirin nonresponsiveness in addition to clopidogrel nonresponsiveness and whether this association identifies patients at an increased risk of drug-eluting stent (DES) thrombosis. BACKGROUND Nonresponsiveness to clopidogrel is a predictor of DES thrombosis. No prospective data exist about the possible association of dual nonresponsiveness to clopidogrel and aspirin with DES thrombosis. METHODS Platelet function was assessed after a loading dose of 600 mg clopidogrel in 746 patients who had successful DES implantation followed by 6-month dual-antiplatelet therapy. Platelet reactivity was assessed by light transmittance aggregometry using adenosine 5'-diphosphate, arachidonic acid, and collagen. The primary end point was definite/probable DES thrombosis at 6 months. The secondary end point was the composite of cardiac mortality and DES thrombosis. RESULTS The incidence of dual nonresponsiveness to aspirin and clopidogrel was 6%. Definite/probable DES thrombosis was significantly higher in dual aspirin and clopidogrel nonresponders (11.1%) than in clopidogrel and aspirin responders (2.1%, p < 0.001), isolated clopidogrel nonresponders (2.2%, p < 0.05), or aspirin nonresponders (2.3%, p < 0.05). The incidence of the secondary end point was 4.4% in isolated clopidogrel nonresponders, 2.3% in isolated aspirin nonresponders, and 13.3% in dual aspirin and clopidogrel nonresponders. Dual clopidogrel and aspirin nonresponsiveness was an independent predictor of DES thrombosis (hazard ratio: 3.18, 95% confidence interval: 1.14 to 8.83, p = 0.027) and the composite of cardiac mortality and DES thrombosis (hazard ratio: 2.94, 95% confidence interval: 1.16 to 7.41, p = 0.022). CONCLUSIONS Dual nonresponsiveness to aspirin and clopidogrel is a relatively infrequent condition that identifies patients at a very high risk of DES thrombosis or death.
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Affiliation(s)
- Anna Maria Gori
- Department of Medical and Surgical Critical Care, University of Florence, Florence, Italy
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Greenbaum AB, Ohman EM, Gibson CM, Borzak S, Stebbins AL, Lu M, Le May MR, Stankowski JE, Emanuelsson H, Weaver WD. Preliminary experience with intravenous P2Y12 platelet receptor inhibition as an adjunct to reduced-dose alteplase during acute myocardial infarction: results of the Safety, Tolerability and Effect on Patency in Acute Myocardial Infarction (STEP-AMI) angiographic trial. Am Heart J 2007; 154:702-9. [PMID: 17892995 DOI: 10.1016/j.ahj.2007.06.001] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2005] [Accepted: 06/04/2007] [Indexed: 11/20/2022]
Abstract
BACKGROUND Fibrinolytic therapy for acute myocardial infarction (AMI) results in normal flow in only about half of patients. Adjunctive treatment with potent antiplatelet and antithrombin agents increases arterial patency but is associated with excessive bleeding. Cangrelor (formerly AR-C69931MX) is a rapidly acting, specific antagonist of platelet aggregation via binding to the adenosine diphosphate P2Y12 receptor subtype. The aim of this study was to assess the safety and coronary artery patency of cangrelor as an adjunct to alteplase (tissue plasminogen activator [t-PA]). METHODS Patients with AMI received aspirin, heparin, and an intravenous infusion of either cangrelor alone, full-dose t-PA alone, or 1 of 3 doses of cangrelor along with half-dose t-PA. The primary end point was Thrombolysis in Myocardial Infarction (TIMI) grade 3 flow at 60 minutes. Secondary end points included TIMI frame count, TIMI myocardial perfusion grade, extent of ST-segment resolution, composite clinical events, and bleeding. RESULTS Ninety-two of planned 180 patients were enrolled. The combination of cangrelor and half-dose t-PA resulted in similar 60-minute patency as full-dose t-PA alone (55% vs 50%, P = not significant) and greater patency than with cangrelor alone (55% vs 18%, P < .05). The percentage of patients achieving >70% ST-segment resolution at 60 minutes tended to be greater with combination therapy than with either cangrelor or t-PA alone (28% vs 13%, P = .13 and 28% vs 14%, P = .30, respectively). Bleeding and adverse clinical events were comparable among the groups. CONCLUSION This first experience with the intravenous P2Y12 receptor inhibitor, cangrelor, suggests the potential of this compound as an adjunct to fibrinolysis during treatment of AMI.
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Sakariassen KS. Thrombus formation on apex of arterial stenoses: the need for a fluid high shear stenosis diagnostic device. Future Cardiol 2007; 3:193-201. [DOI: 10.2217/14796678.3.2.193] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
This review is focused upon the studies of thrombus formation in human non-anticoagulated blood on an apex of an eccentric stenosis positioned in the blood flow channel of a parallel-plate perfusion chamber. Thrombus formation in blood from healthy individuals and patients with various bleeding disorders, as well as the effects of a diet supplement and pharmacological interventions, are discussed in view of thrombus-forming mechanisms under these complex blood-flow conditions. Hallmarks of this significantly enhanced thrombus formation are the apparent dependence on thrombin generation, shear-induced platelet activation, induction of platelet procoagulant activity and pronounced platelet microparticle formation that parallel the growth of these fibrin-rich thrombi. The development of miniature models of these blood-flow devices for diagnostic purposes is suggested for the assessment and monitoring of the efficacy of antithrombotic regimens in blood from patients with atherosclerotic disease in parallel with assessments of platelet microparticle formation, shear-induced platelet activation and platelet procoagulant activity.
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Denis CV, Wagner DD. Platelet adhesion receptors and their ligands in mouse models of thrombosis. Arterioscler Thromb Vasc Biol 2007; 27:728-39. [PMID: 17272754 DOI: 10.1161/01.atv.0000259359.52265.62] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Platelet adhesion and aggregation at sites of vascular injury are two key events in hemostasis and thrombosis. Because of exciting advances in genetic engineering, the mouse has become an important and frequently used model to unravel the molecular mechanisms underlying the multistep process leading to the formation of a stable platelet plug. In gene-targeted mice, the crucial importance of platelet adhesion receptors such as glycoprotein Ib alpha or the alphaIIb beta3 integrin has been confirmed and further clarified. Their absence leads to highly impaired thrombus formation, independent of the model used to induce vascular injury. In contrast, the relative contribution of other receptors, such as glycoprotein VI, or of various platelet ligands may be regulated by the severity of injury, the type of vessel injured, and the signaling pathways that are generated. Murine models have also helped improve understanding of the second wave of events that leads to stabilization of the platelet aggregate. Despite the current limitations due to lack of standardization and the virtual absence of thrombosis models in diseased vessels, there is no doubt that the mouse will play a key role in the discovery and characterization of the next generation of antithrombotic agents. This review focuses on key findings about the molecular mechanisms supporting hemostasis and thrombosis that have been obtained with genetically engineered mouse models deficient in various platelet adhesion receptors and ligands. Combination of these models with sophisticated methods allowing direct visualization of platelet-vessel wall interactions after injury greatly contributed to recent advances in the field.
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Sakariassen KS. Blood flow devices in medical research and clinical testing in humans: are we approaching personalized medicine? Future Cardiol 2007; 3:71-90. [DOI: 10.2217/14796678.3.1.71] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
This review focuses on studies of blood flow devices employed in man to unravel the mechanisms of bleeding and thrombotic disorders, and on the characterization of novel experimental antithrombotic entities and drug candidates in biopharmaceutical research and development. Clinical studies with drug candidates and new therapeutic strategies have also been performed, and the predictability of these experimental approaches to clinical situations is excellent. Based on the solid validation of these flow devices, miniature flow devices employing nonanticoagulated blood drawn directly from an antecubital vein should be developed for diagnostic purposes. It is anticipated that such a diagnostic flow device could develop into a personalized medicine approach.
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Stone GW, McLaurin BT, Cox DA, Bertrand ME, Lincoff AM, Moses JW, White HD, Pocock SJ, Ware JH, Feit F, Colombo A, Aylward PE, Cequier AR, Darius H, Desmet W, Ebrahimi R, Hamon M, Rasmussen LH, Rupprecht HJ, Hoekstra J, Mehran R, Ohman EM. Bivalirudin for patients with acute coronary syndromes. N Engl J Med 2006; 355:2203-16. [PMID: 17124018 DOI: 10.1056/nejmoa062437] [Citation(s) in RCA: 1008] [Impact Index Per Article: 56.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
BACKGROUND Current guidelines for patients with moderate- or high-risk acute coronary syndromes recommend an early invasive approach with concomitant antithrombotic therapy, including aspirin, clopidogrel, unfractionated or low-molecular-weight heparin, and glycoprotein IIb/IIIa inhibitors. We evaluated the role of thrombin-specific anticoagulation with bivalirudin in such patients. METHODS We assigned 13,819 patients with acute coronary syndromes to one of three antithrombotic regimens: unfractionated heparin or enoxaparin plus a glycoprotein IIb/IIIa inhibitor, bivalirudin plus a glycoprotein IIb/IIIa inhibitor, or bivalirudin alone. The primary end points were a composite ischemia end point (death, myocardial infarction, or unplanned revascularization for ischemia), major bleeding, and the net clinical outcome, defined as the combination of composite ischemia or major bleeding. RESULTS Bivalirudin plus a glycoprotein IIb/IIIa inhibitor, as compared with heparin plus a glycoprotein IIb/IIIa inhibitor, was associated with noninferior 30-day rates of the composite ischemia end point (7.7% and 7.3%, respectively), major bleeding (5.3% and 5.7%), and the net clinical outcome end point (11.8% and 11.7%). Bivalirudin alone, as compared with heparin plus a glycoprotein IIb/IIIa inhibitor, was associated with a noninferior rate of the composite ischemia end point (7.8% and 7.3%, respectively; P=0.32; relative risk, 1.08; 95% confidence interval [CI], 0.93 to 1.24) and significantly reduced rates of major bleeding (3.0% vs. 5.7%; P<0.001; relative risk, 0.53; 95% CI, 0.43 to 0.65) and the net clinical outcome end point (10.1% vs. 11.7%; P=0.02; relative risk, 0.86; 95% CI, 0.77 to 0.97). CONCLUSIONS In patients with moderate- or high-risk acute coronary syndromes who were undergoing invasive treatment with glycoprotein IIb/IIIa inhibitors, bivalirudin was associated with rates of ischemia and bleeding that were similar to those with heparin. Bivalirudin alone was associated with similar rates of ischemia and significantly lower rates of bleeding. (ClinicalTrials.gov number, NCT00093158 [ClinicalTrials.gov].).
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Affiliation(s)
- Gregg W Stone
- Columbia University Medical Center and the Cardiovascular Research Foundation, New York, NY 10022, USA.
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Greenbaum AB, Grines CL, Bittl JA, Becker RC, Kereiakes DJ, Gilchrist IC, Clegg J, Stankowski JE, Grogan DR, Harrington RA, Emanuelsson H, Weaver WD. Initial experience with an intravenous P2Y12 platelet receptor antagonist in patients undergoing percutaneous coronary intervention: results from a 2-part, phase II, multicenter, randomized, placebo- and active-controlled trial. Am Heart J 2006; 151:689.e1-689.e10. [PMID: 16504633 DOI: 10.1016/j.ahj.2005.11.014] [Citation(s) in RCA: 159] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2004] [Accepted: 11/30/2005] [Indexed: 11/17/2022]
Abstract
BACKGROUND Platelet-initiated acute thrombosis and coronary embolization are fundamental in the pathophysiology of complications during percutaneous coronary intervention (PCI). Cangrelor (formerly AR-C69931MX) is a novel, rapidly acting, intravenous, specific antagonist of platelet aggregation via binding to the adenosine diphosphate (ADP) P2Y12 receptor subtype. The primary aims of this study were to assess the initial safety and pharmacodynamics of cangrelor in patients undergoing PCI. METHODS In part 1, patients undergoing PCI were randomized to an 18- to 24-hour of either placebo, 1-, 2-, or 4-microg/kg per minute cangrelor in addition to aspirin and heparin beginning before PCI. In part 2, patients were randomized to receive either cangrelor (4 microg/kg per minute) or abciximab before PCI. The primary end point was the composite incidence of major and minor bleeding through 7 days. Secondary end points included the occurrence of major adverse coronary events (death, MI, and unplanned repeat coronary intervention) through 30 days plus ex vivo platelet aggregation and bleeding times. RESULTS Two hundred patients (3 dosage groups and placebo) were studied in part 1, and 199 additional patients were then randomized in the second part, comparing 1 dose of cangrelor and abciximab. Combined major and minor bleeding occurred in 13% of those receiving cangrelor and in 8% in those randomized to placebo (P = non significant [NS]) during part 1 and in 7% receiving cangrelor compared with 10% randomized to abciximab (P = NS), during part 2. The 30-day composite incidence of adverse cardiac events was similar between those receiving cangrelor and those receiving abciximab during part 2 (7.6% vs 5.3%, respectively, P = NS). Mean inhibition of ex vivo platelet aggregation in response to 3 micromol/L ADP at steady state was 100% for both cangrelor 4 microg/kg per minute and abciximab groups in part 2. After termination of infusion, platelet aggregation returned to baseline response more rapidly with cangrelor compared with abciximab. There was a trend toward longer bleeding time prolongation and lower platelet count with abciximab compared with cangrelor. CONCLUSIONS This initial experience with intravenous cangrelor during PCI suggests an acceptable risk of bleeding and adverse cardiac events while achieving rapid, reversible inhibition of platelet aggregation via competitive binding to the ADP P2Y12 platelet receptor with less prolongation of bleeding time then the glycoprotein IIb/IIIa receptor antagonist abciximab.
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Aktas B, Pozgajova M, Bergmeier W, Sunnarborg S, Offermanns S, Lee D, Wagner DD, Nieswandt B. Aspirin Induces Platelet Receptor Shedding via ADAM17 (TACE). J Biol Chem 2005; 280:39716-22. [PMID: 16179345 DOI: 10.1074/jbc.m507762200] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Aspirin is effective in the therapy of cardiovascular diseases, because it causes acetylation of cyclooxygenase 1 (COX-1) leading to irreversible inhibition of platelets. Additional mechanisms can be suspected, because patients treated with other platelet COX inhibitors such as indomethacin do not display an increased bleeding tendency as observed for aspirin-treated patients. Recently, aspirin and other anti-inflammatory drugs were shown to induce shedding of L-selectin in neutrophils in a metalloproteinase-dependent manner. Therefore, we investigated the effects of aspirin on the von Willebrand Factor receptor complex glycoprotein (GP) Ib-V-IX, whose lack or dysfunction causes bleeding in patients. As quantified by fluorescence-activated cell sorting analysis in whole blood, aspirin, but not its metabolite salicylic acid, induced dose-dependent shedding of human and murine GPIbalpha and GPV from the platelet surface, whereas other glycoproteins remained unaffected by this treatment. Biotinylated fragments of GPV were detected by immunoprecipitation in the supernatant of washed mouse platelets, and the expression level of GPIbalpha was decreased in these platelets as measured by Western blot analysis. Although shedding occurred normally in COX-1-deficient murine platelets, shedding was completely blocked by a broad-range metalloproteinase inhibitor and, more importantly, in mouse platelets expressing an inactive form of ADAM17. Shed fragments of GPIbalpha and GPV were elevated in the plasma of aspirin-injected mice compared with animals injected with control buffer. These data demonstrate that aspirin at high concentrations induces shedding of GPIbalpha and GPV by an ADAM17-dependent mechanism and that this process can occur in vivo.
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Affiliation(s)
- Barsom Aktas
- Rudolf Virchow Center for Experimental Biomedicine, Versbacherstrasse 9, 97078 Würzburg, Germany
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Wu CC, Wang TW, Wang WY, Hsieh PW, Wu YC. 2-(2-Br-phenyl)-8-methoxy-benzoxazinone (HPW-RX2), a direct thrombin inhibitor with a suppressive effect on thromboxane formation in platelets. Eur J Pharmacol 2005; 527:37-43. [PMID: 16313903 DOI: 10.1016/j.ejphar.2005.10.023] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2005] [Revised: 10/06/2005] [Accepted: 10/18/2005] [Indexed: 11/15/2022]
Abstract
2-(2-Br-phenyl)-8-methoxy-benzoxazinone (HPW-RX2), a newly synthetic benzoxazinone derivative, has previously been shown to inhibit rabbit platelet aggregation caused by thrombin and arachidonic acid. In the present study, the mechanism for the antiplatelet effect of HPW-RX2 was further investigated. In human platelets, HPW-RX2 concentration-dependently inhibited platelet aggregation, ATP release, P-selectin expression, and intracellular calcium mobilization caused by thrombin. In contrast, HPW-RX2 had no significant effect on either SFLLRN- or GYPGKF-induced platelet aggregation, indicating that HPW-RX2 did not interfere with platelet thrombin receptors. Moreover, HPW-RX2 inhibited the amidolytic activity of thrombin and prolonged the fibrinogen clotting time. These results suggest that the inhibitory effect of HPW-RX2 on thrombin-induced platelet aggregation is via direct inhibition of thrombin proteolytic activity. Besides the inhibition on thrombin, HPW-RX2 also prevented platelet aggregation, ATP release, and increase in [Ca2+]i caused by arachidonic acid and low concentration collagen. In a parallel manner, both arachidonic acid-induced thromboxane B2 and prostaglandin D2 formations were decreased in platelets treated with HPW-RX2. This indicates that HPW-RX2 is able to inhibit the arachidonic acid cascade at the cyclooxygenase level. This is the first report of a benzoxazinone derivative possessing both thrombin and cyclooxygenase inhibitory properties. The dual effect of HPW-RX2 might provide extra therapeutic benefits for treatment of arterial thrombosis.
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Affiliation(s)
- Chin-Chung Wu
- Graduate Institute of Natural Products, Kaohsiung Medical University, Kaohsiung, Taiwan.
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Wang Y, Sakuma M, Chen Z, Ustinov V, Shi C, Croce K, Zago AC, Lopez J, Andre P, Plow E, Simon DI. Leukocyte engagement of platelet glycoprotein Ibalpha via the integrin Mac-1 is critical for the biological response to vascular injury. Circulation 2005; 112:2993-3000. [PMID: 16260637 DOI: 10.1161/circulationaha.105.571315] [Citation(s) in RCA: 142] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Leukocyte-platelet interactions are critical in the initiation and progression of atherosclerosis as well as restenosis. Although the leukocyte integrin Mac-1 (alphaMbeta2, CD11b/CD18) has been implicated in the firm adhesion and transmigration of leukocytes at sites of platelet deposition, the precise alphaMbeta2 counterligand responsible for mediating adhesion-strengthening interactions between neutrophils and platelets in vivo has not previously been identified. METHODS AND RESULTS Our previous studies have established the P201-K217 sequence in the alphaMI domain as the binding site for platelet glycoprotein (GP) Ibalpha. Here we report that antibody targeting of alphaM(P201-K217) reduced alphaMbeta2-dependent adhesion to GP Ibalpha but not other alphaMbeta2 ligands, including fibrinogen, intercellular adhesion molecule-1, and junctional adhesion molecule-3. Anti-alphaM(P201-K217) inhibited the firm adhesion of both human and murine leukocytes to adherent platelets under laminar flow conditions. In a mouse femoral artery wire injury model, antibody targeting of alphaM(P201-K217) reduced leukocyte accumulation after injury that was accompanied by inhibition of cellular proliferation and neointimal thickening. CONCLUSIONS This study demonstrates that GP Ibalpha is a physiologically relevant ligand for alphaMbeta2 and that integrin engagement of GP Ibalpha is critical to leukocyte function and the biological response to vascular injury. These observations establish a molecular target for selectively disrupting leukocyte-platelet complexes that promote inflammation in thrombosis and restenosis.
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Affiliation(s)
- Yunmei Wang
- Cardiovascular Division, Brigham and Women's Hospital, Boston, MA 02115, USA
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Abstract
The current standard of care for the treatment of arterial thrombosis includes anticoagulants and three classes of antiplatelet agents--aspirin, thienopyridines and glycoprotein IIb-IIIa antagonists. Although these drugs have had a significant impact on morbidity and mortality in several patient populations, up to 15% of the high risk patients with acute coronary syndrome continue to suffer from ischemic events. This problem may occur, in part, because the platelets in many patients are non-responsive to aspirin and clopidogrel. Murine models now indicate that platelets are not only responsible for arterial occlusion, they are also involved in the progression of atherosclerotic disease. New opportunities have emerged identifying potential targets and strategies for drug discovery suited to address these deficiencies by more effectively modulating platelet adhesion, thrombus growth, thrombus stability and the pro-inflammatory activity of platelets. In addition, a growing need has emerged for the development of bedside devices capable of bringing personalized medicine to patients being treated with antithrombotic drugs in order to measure the pharmacodynamic activities of new therapies, to assess the activities achieved by combined antithrombotic therapy, and to identify patients that fail to respond.
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Affiliation(s)
- D R Phillips
- Portola Pharmaceuticals, Inc., San Francisco, CA 94402, USA.
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Nanda N, Andre P, Bao M, Clauser K, Deguzman F, Howie D, Conley PB, Terhorst C, Phillips DR. Platelet aggregation induces platelet aggregate stability via SLAM family receptor signaling. Blood 2005; 106:3028-34. [PMID: 16037392 DOI: 10.1182/blood-2005-01-0333] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Platelet aggregation is a dynamic entity, capable of directing its own growth and stability via the activation of signaling cascades that lead to the expression and secretion of various secondary agonists. Here we show that the signaling pathways triggered during platelet aggregation include an intrinsic pro-thrombotic activity mediated by 2 homophilic adhesion molecules, CD84 and CD150 (SLAM [signaling lymphocyte activation molecule]), which are tyrosine phosphorylated in a platelet aggregation-dependent fashion. The 2 CD84/SLAM adapter proteins, SAP (SLAM-associated protein) and EAT-2 (EWS-activated transcript-2), were found in platelets; only SAP, however, was found to immunoprecipitate with tyrosine-phosphorylated SLAM. The immobilized extracellular domain of CD84 promoted microaggregate formation, while SAP-deficient platelets demonstrated defective spreading on immobilized CD84, demonstrating a functional role in platelets for SLAM family interactions. Finally, analysis of SLAM-deficient mice revealed an overall defect in platelet aggregation in vitro and a delayed arterial thrombotic process in vivo. The data indicate that signaling of the adhesion molecules in the SLAM family, activated by proximity during aggregation, further stabilize platelet-platelet interactions in thrombosis.
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Affiliation(s)
- Nisha Nanda
- Portola Pharmaceuticals, 270 E Grand Ave, Suite 22, San Francisco, CA 94080, USA
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Gachet C. The platelet P2 receptors as molecular targets for old and new antiplatelet drugs. Pharmacol Ther 2005; 108:180-92. [PMID: 15955565 DOI: 10.1016/j.pharmthera.2005.03.009] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2005] [Accepted: 03/24/2005] [Indexed: 12/15/2022]
Abstract
Platelet activation by ADP and ATP plays a crucial role in haemostasis and thrombosis, and their so-called P2 receptors are potential targets for antithrombotic drugs. The ATP-gated channel P2X1 and the 2 G protein-coupled P2Y1 and P2Y12 ADP receptors selectively contribute to platelet aggregation. The P2Y1 receptor is responsible for ADP-induced shape change and weak and transient aggregation, while the P2Y12 receptor is responsible for the completion and amplification of the response to ADP and to all platelet agonists, including thromboxane A2 (TXA2), thrombin, and collagen. The P2X1 receptor is involved in platelet shape change and in activation by collagen under shear conditions. Due to its central role in the formation and stabilization of a thrombus, the P2Y12 receptor is a well-established target of antithrombotic drugs like ticlopidine or clopidogrel, which have proved efficacy in many clinical trials and experimental models of thrombosis. Competitive P2Y12 antagonists have also been shown to be effective in experimental thrombosis as well as in several clinical trials. Studies in P2Y1 and P2X1 knockout mice and experimental thrombosis models using selective P2Y1 and P2X1 antagonists have shown that, depending on the conditions, these receptors could also be potential targets for new antithrombotic drugs.
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Affiliation(s)
- Christian Gachet
- INSERM U.311, Etablissement Français du Sang-Alsace, 10 rue Spielmann, B.P. No. 36, 67065 Strasbourg Cedex, France.
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Jefferson BK, Foster JH, McCarthy JJ, Ginsburg G, Parker A, Kottke-Marchant K, Topol EJ. Aspirin resistance and a single gene. Am J Cardiol 2005; 95:805-8. [PMID: 15757620 DOI: 10.1016/j.amjcard.2004.11.045] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/21/2004] [Revised: 11/11/2004] [Accepted: 11/11/2004] [Indexed: 10/25/2022]
Abstract
This study examined the association of single nucleotide polymorphisms in 4 candidate genes in a cohort of subjects with aspirin resistance. Aspirin resistance was significantly associated with genetic variation in the platelet surface adenosine 5-diphosphate receptor gene P2Y1.
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Schneider DJ, Whitaker DA, Sobel BE. Efficiency in clinical research: assessment in vitro of potential anti-thrombotic drug interactions. Coron Artery Dis 2004; 15:177-81. [PMID: 15096999 DOI: 10.1097/00019501-200405000-00007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To determine whether testing in vitro of combinations of anti-thrombotic agents can identify potentially important interactions, we evaluated the combination of rNAPc2 with antagonists of platelet GP IIb-IIIa to identify potentially altered anticoagulant properties, antiplatelet effects, or both. METHODS Blood was obtained from healthy subjects who were taking aspirin (325 mg/day). Selected concentrations of rNAPc2, enoxaparin, and GP IIb-IIIa inhibitors were added in vitro. Platelet function was assessed with the use of flow cytometry. RESULTS No effect on clotting or platelet inhibition was apparent when abciximab was added to the combination of aspirin, enoxaparin, and rNAPc2 at concentrations up to 250 ng/ml. A modest (less than 10%, P <0.02) effect on the time to clot assessed with the activated clotting time was demonstrated when either eptifibatide or tirofiban was combined with aspirin and enoxaparin plus rNAPc2. rNAPc2 did not alter antiplatelet effects of eptifibatide. By contrast, a modest, approximately 10%, increase in the inhibition of fibrinogen binding (P <0.01) was seen when rNAPc2 was added to the combination of aspirin, enoxaparin, and tirofiban. CONCLUSIONS The lack of an exaggerated effect on clotting and platelet function when GP IIb-IIIa inhibitors were combined with rNAPc2, aspirin, and enoxaparin suggests that no substantial increment in the incidence of bleeding would be observed when concentrations of rNAPc2 up to 250 ng/ml were to be used in clinical studies. More extensive use of testing in vitro in advance of large-scale clinical trials of anti-thrombotic agents and regimens is likely to enhance their design and implementation.
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Affiliation(s)
- David J Schneider
- Department of Medicine, University of Vermont, Burlington, Vermont, USA.
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