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Dubut J, Goin V, Derray C, Huguenin Y, Fiore M. Targeting tissue factor pathway inhibitor with concizumab to improve hemostasis in patients with Glanzmann thrombasthenia: an in vitro study. J Thromb Haemost 2024; 22:2589-2600. [PMID: 38880178 DOI: 10.1016/j.jtha.2024.05.033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Revised: 04/27/2024] [Accepted: 05/30/2024] [Indexed: 06/18/2024]
Abstract
BACKGROUND Glanzmann thrombasthenia (GT) is caused by an inherited defect of platelet αIIbβ3 integrin. Concizumab, a monoclonal antibody specific for tissue factor pathway inhibitor, abolishes its anticoagulant effect. OBJECTIVES To evaluate the in vitro ability of concizumab to improve hemostasis in GT. METHODS The effects of concizumab were evaluated in whole blood or platelet-rich plasma from GT patients (n = 5-9) using a thrombin generation assay, rotational thromboelastometry (ROTEM), a global fibrinolytic capacity assay, and a flow chamber assay (Total Thrombus formation Analysis System). Washed platelets (WPs) and 20 nM recombinant activated factor VII (rFVIIa) were included for comparison. RESULTS The lag time in the thrombin generation assay was significantly longer (+85%; P < .0001) in GT patients than in controls. WPs, rFVIIa, and concizumab each significantly improved thrombin generation profiles. The ROTEM clotting time (CT) was significantly longer in GT patients than in controls (677 seconds vs 523 seconds; P = .03). However, CT improved after adding WPs, rFVIIa, or concizumab. Under flow, occlusive thrombi were present in all healthy controls after 10 minutes, whereas platelet-fibrin depositions were not seen in GT patients. Subocclusive or occlusive thrombi formed when GT blood was mixed with WPs, rFVIIa, or concizumab. Clots in GT platelet-rich plasma were more susceptible to fibrinolysis and were improved by WPs, rFVIIa, or concizumab. CONCLUSION Concizumab enhanced thrombin generation, decreased the ROTEM CT, improved thrombus formation under flow, and reduced clot lysis. Our results demonstrate the potential of concizumab for subcutaneous prophylaxis in GT patients.
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Affiliation(s)
- Jade Dubut
- Department of Haematology, University Hospital of Bordeaux, Pessac, France; Institut National de la Santé et de la Recherche Médicale U1034, Biology of Cardiovascular Disease, Pessac, France
| | - Valérie Goin
- French Reference Centre for Inherited Platelet Disorders, University Hospital of Bordeaux, Pessac, France
| | - Cloé Derray
- Department of Haematology, University Hospital of Bordeaux, Pessac, France
| | - Yoann Huguenin
- Competence Centre for Inherited Bleeding Disorders, University Hospital of Bordeaux, Bordeaux, France
| | - Mathieu Fiore
- Department of Haematology, University Hospital of Bordeaux, Pessac, France; Institut National de la Santé et de la Recherche Médicale U1034, Biology of Cardiovascular Disease, Pessac, France; French Reference Centre for Inherited Platelet Disorders, University Hospital of Bordeaux, Pessac, France.
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2
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Baksamawi HA, Alexiadis A, Vigolo D, Brill A. Platelet accumulation in an endothelium-coated elastic vein valve model of deep vein thrombosis is mediated by GPIb α-VWF interaction. Front Cardiovasc Med 2023; 10:1167884. [PMID: 37180784 PMCID: PMC10174463 DOI: 10.3389/fcvm.2023.1167884] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Accepted: 03/28/2023] [Indexed: 05/16/2023] Open
Abstract
Deep vein thrombosis is a life-threatening disease that takes millions of people's lives worldwide. Given both technical and ethical issues of using animals in research, it is necessary to develop an appropriate in vitro model that would recapitulate the conditions of venous thrombus development. We present here a novel microfluidics vein-on-a-chip with moving valve leaflets to mimic the hydrodynamics in a vein, and Human Umbilical Vein Endothelial Cell (HUVEC) monolayer. A pulsatile flow pattern, typical for veins, was used in the experiments. Unstimulated human platelets, reconstituted with the whole blood, accumulated at the luminal side of the leaflet tips proportionally to the leaflet flexibility. Platelet activation by thrombin induced robust platelet accrual at the leaflet tips. Inhibition of glycoprotein (GP) IIb-IIIa did not decrease but, paradoxically, slightly increased platelet accumulation. In contrast, blockade of the interaction between platelet GPIbα and A1 domain of von Willebrand factor completely abolished platelet deposition. Stimulation of the endothelium with histamine, a known secretagogue of Weibel-Palade bodies, promoted platelet accrual at the basal side of the leaflets, where human thrombi are usually observed. Thus, platelet deposition depends on the leaflet flexibility, and accumulation of activated platelets at the valve leaflets is mediated by GPIbα-VWF interaction.
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Affiliation(s)
- Hosam Alden Baksamawi
- School of Chemical Engineering, University of Birmingham, Birmingham, United Kingdom
| | - Alessio Alexiadis
- School of Chemical Engineering, University of Birmingham, Birmingham, United Kingdom
- School of Biomedical Engineering, The University of Sydney, Sydney, NSW, Australia
| | - Daniele Vigolo
- School of Chemical Engineering, University of Birmingham, Birmingham, United Kingdom
- School of Biomedical Engineering, The University of Sydney, Sydney, NSW, Australia
- The University of Sydney Nano Institute, The University of Sydney, Sydney, NSW, Australia
| | - Alexander Brill
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
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3
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Bourguignon A, Tasneem S, Hayward CPM. Update on platelet procoagulant mechanisms in health and in bleeding disorders. Int J Lab Hematol 2022; 44 Suppl 1:89-100. [PMID: 36074709 DOI: 10.1111/ijlh.13866] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Accepted: 04/20/2022] [Indexed: 11/28/2022]
Abstract
Platelet procoagulant mechanisms are emerging to be complex and important to achieving haemostasis. The mechanisms include the release of procoagulant molecules from platelet storage granules, and strong agonist-induced expression of procoagulant phospholipids on the outer platelet membrane for tenase and prothrombinase assembly. The release of dense granule polyphosphate is important to platelet procoagulant function as it promotes the activation of factors XII, XI and V, inhibits tissue factor pathway inhibitor and fibrinolysis, and strengthens fibrin clots. Platelet procoagulant function also involves the release of partially activated factor V from platelets. Scott syndrome has provided important insights on the mechanisms that regulate procoagulant phospholipids expression on the external platelet membrane, which require strong agonist stimulation that increase cystolic calcium levels, mitochondrial calcium uptake, the loss of flippase function and activation of the transmembrane scramblase protein anoctamin 6. There have been advances in the methods used to directly and indirectly assess platelet procoagulant function in health and disease. Assessments of thrombin generation with platelet rich plasma samples has provided new insights on how platelet procoagulant function is altered in inherited platelet disorders, and how platelets influence the bleeding phenotype of a number of severe coagulation factor deficiencies. Several therapies, including desmopressin and recombinant factor VIIa, improve thrombin generation by platelets. There is growing interest in targeting platelet procoagulant function for therapeutic benefit. This review highlights recent advances in our understanding of platelet-dependent procoagulant mechanisms in health and in bleeding disorders.
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Affiliation(s)
- Alex Bourguignon
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Canada.,Hamilton Regional Laboratory Medicine Program, Hamilton, Canada
| | - Subia Tasneem
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Canada
| | - Catherine P M Hayward
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Canada.,Hamilton Regional Laboratory Medicine Program, Hamilton, Canada.,Department of Medicine, McMaster University, Hamilton, Canada
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4
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Aliotta A, Bertaggia Calderara D, Zermatten MG, Marchetti M, Alberio L. Thrombocytopathies: Not Just Aggregation Defects-The Clinical Relevance of Procoagulant Platelets. J Clin Med 2021; 10:jcm10050894. [PMID: 33668091 PMCID: PMC7956450 DOI: 10.3390/jcm10050894] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 01/31/2021] [Accepted: 02/12/2021] [Indexed: 01/08/2023] Open
Abstract
Platelets are active key players in haemostasis. Qualitative platelet dysfunctions result in thrombocytopathies variously characterized by defects of their adhesive and procoagulant activation endpoints. In this review, we summarize the traditional platelet defects in adhesion, secretion, and aggregation. In addition, we review the current knowledge about procoagulant platelets, focusing on their role in bleeding or thrombotic pathologies and their pharmaceutical modulation. Procoagulant activity is an important feature of platelet activation, which should be specifically evaluated during the investigation of a suspected thrombocytopathy.
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Affiliation(s)
- Alessandro Aliotta
- Hemostasis and Platelet Research Laboratory, Division of Hematology and Central Hematology Laboratory, Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), CH-1010 Lausanne, Switzerland; (A.A.); (D.B.C.); (M.G.Z.); (M.M.)
| | - Debora Bertaggia Calderara
- Hemostasis and Platelet Research Laboratory, Division of Hematology and Central Hematology Laboratory, Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), CH-1010 Lausanne, Switzerland; (A.A.); (D.B.C.); (M.G.Z.); (M.M.)
| | - Maxime G. Zermatten
- Hemostasis and Platelet Research Laboratory, Division of Hematology and Central Hematology Laboratory, Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), CH-1010 Lausanne, Switzerland; (A.A.); (D.B.C.); (M.G.Z.); (M.M.)
| | - Matteo Marchetti
- Hemostasis and Platelet Research Laboratory, Division of Hematology and Central Hematology Laboratory, Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), CH-1010 Lausanne, Switzerland; (A.A.); (D.B.C.); (M.G.Z.); (M.M.)
- Service de Médecine Interne, Hôpital de Nyon, CH-1260 Nyon, Switzerland
| | - Lorenzo Alberio
- Hemostasis and Platelet Research Laboratory, Division of Hematology and Central Hematology Laboratory, Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), CH-1010 Lausanne, Switzerland; (A.A.); (D.B.C.); (M.G.Z.); (M.M.)
- Correspondence:
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5
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Tohidi-Esfahani I, Lee CSM, Liang HPH, Chen VMY. Procoagulant platelets: Laboratory detection and clinical significance. Int J Lab Hematol 2021; 42 Suppl 1:59-67. [PMID: 32543068 DOI: 10.1111/ijlh.13197] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2020] [Accepted: 03/10/2020] [Indexed: 12/15/2022]
Abstract
Platelets play a critical role in both haemostasis and thrombosis, and it is now evident that not all platelets behave the same when they are called to action. A functionally distinct subpopulation of platelets forms in response to maximal agonist stimulation: the procoagulant platelet. This platelet subpopulation is defined by its ability to expose phosphatidylserine on its surface, allowing for coagulation factor complexes to form and generate bursts of thrombin and fibrin to stabilize platelet clots. Reduced levels of procoagulant platelets have been linked to bleeding in Scott's syndrome and haemophilia A patients, and elevated levels have been demonstrated in many thrombotic disorders, including identifying patients at higher risk for stroke recurrence. One obstacle for incorporating an assay for measuring procoagulant platelets into clinical management algorithms is the lack of consensus on the exact definition and markers for this subpopulation. This review will outline the biological characteristics of procoagulant platelets and the laboratory assays currently used to identify them in research settings. It will summarize the findings of clinical research demonstrating the relevance of measuring the procoagulant platelet levels in patients and will discuss how an appropriate assay can be used to elucidate the mechanism behind the formation of this subpopulation, facilitating novel drug discovery to improve upon current outcomes in cardiovascular and other thrombotic disorders.
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Affiliation(s)
- Ibrahim Tohidi-Esfahani
- ANZAC Research Institute, University of Sydney, Sydney, New South Wales, Australia.,Department of Haematology, Concord Repatriation General Hospital, Sydney, New South Wales, Australia
| | - Christine S M Lee
- ANZAC Research Institute, University of Sydney, Sydney, New South Wales, Australia
| | - Hai Po H Liang
- ANZAC Research Institute, University of Sydney, Sydney, New South Wales, Australia
| | - Vivien M Y Chen
- ANZAC Research Institute, University of Sydney, Sydney, New South Wales, Australia.,Department of Haematology, Concord Repatriation General Hospital, Sydney, New South Wales, Australia
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6
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Aliotta A, Krüsi M, Bertaggia Calderara D, Zermatten MG, Gomez FJ, Batista Mesquita Sauvage AP, Alberio L. Characterization of Procoagulant COAT Platelets in Patients with Glanzmann Thrombasthenia. Int J Mol Sci 2020; 21:E9515. [PMID: 33327658 PMCID: PMC7765091 DOI: 10.3390/ijms21249515] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Revised: 12/04/2020] [Accepted: 12/10/2020] [Indexed: 12/22/2022] Open
Abstract
Patients affected by the rare Glanzmann thrombasthenia (GT) suffer from defective or low levels of the platelet-associated glycoprotein (GP) IIb/IIIa, which acts as a fibrinogen receptor, and have therefore an impaired ability to aggregate platelets. Because the procoagulant activity is a dichotomous facet of platelet activation, diverging from the aggregation endpoint, we were interested in characterizing the ability to generate procoagulant platelets in GT patients. Therefore, we investigated, by flow cytometry analysis, platelet functions in three GT patients as well as their ability to generate procoagulant collagen-and-thrombin (COAT) platelets upon combined activation with convulxin-plus-thrombin. In addition, we further characterized intracellular ion fluxes during the procoagulant response, using specific probes to monitor by flow cytometry kinetics of cytosolic calcium, sodium, and potassium ion fluxes. GT patients generated higher percentages of procoagulant COAT platelets compared to healthy donors. Moreover, they were able to mobilize higher levels of cytosolic calcium following convulxin-plus-thrombin activation, which is congruent with the greater procoagulant activity. Further investigations will dissect the role of GPIIb/IIIa outside-in signalling possibly implicated in the regulation of platelet procoagulant activity.
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Affiliation(s)
| | | | | | | | | | | | - Lorenzo Alberio
- Division of Hematology and Central Hematology Laboratory, Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), Rue du Bugnon 46, CH-1011 Lausanne, Switzerland; (A.A.); (M.K.); (D.B.C.); (M.G.Z.); (F.J.G.); (A.P.B.M.S.)
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7
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Gutmann C, Joshi A, Mayr M. Platelet "-omics" in health and cardiovascular disease. Atherosclerosis 2020; 307:87-96. [PMID: 32646580 DOI: 10.1016/j.atherosclerosis.2020.05.022] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2020] [Revised: 04/28/2020] [Accepted: 05/27/2020] [Indexed: 12/21/2022]
Abstract
The importance of platelets for cardiovascular disease was established as early as the 19th century. Their therapeutic inhibition stands alongside the biggest achievements in medicine. Still, certain aspects of platelet pathophysiology remain unclear. This includes platelet resistance to antiplatelet therapy and the contribution of platelets to vascular remodelling and extends beyond cardiovascular disease to haematological disorders and cancer. To address these gaps in our knowledge, a better understanding of the underlying molecular processes is needed. This will be enabled by technologies that capture dysregulated molecular processes and can integrate them into a broader network of biological systems. The advent of -omics technologies, such as mass spectrometry proteomics, metabolomics and lipidomics; highly multiplexed affinity-based proteomics; microarray- or RNA-sequencing-(RNA-seq)-based transcriptomics, and most recently ribosome footprint-based translatomics, has enabled a more holistic understanding of platelet biology. Most of these methods have already been applied to platelets, and this review will summarise this information and discuss future developments in this area of research.
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Affiliation(s)
- Clemens Gutmann
- King's British Heart Foundation Centre, King's College London, 125 Coldharbour Lane, London, SE5 9NU, United Kingdom
| | - Abhishek Joshi
- King's British Heart Foundation Centre, King's College London, 125 Coldharbour Lane, London, SE5 9NU, United Kingdom
| | - Manuel Mayr
- King's British Heart Foundation Centre, King's College London, 125 Coldharbour Lane, London, SE5 9NU, United Kingdom.
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8
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Zhao Z, Zhou Y, Hilton T, Li F, Han C, Liu L, Yuan H, Li Y, Xu X, Wu X, Zhang F, Thiagarajan P, Cap A, Shi FD, Zhang J, Dong JF. Extracellular mitochondria released from traumatized brains induced platelet procoagulant activity. Haematologica 2019; 105:209-217. [PMID: 30975909 PMCID: PMC6939511 DOI: 10.3324/haematol.2018.214932] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Accepted: 04/09/2019] [Indexed: 01/10/2023] Open
Abstract
Coagulopathy often develops soon after acute traumatic brain injury and its cause remains poorly understood. We have shown that injured brains release cellular microvesicles that disrupt the endothelial barrier and induce consumptive coagulopathy. Morphologically intact extracellular mitochondria accounted for 55.2% of these microvesicles, leading to the hypothesis that these extracellular mitochondria are metabolically active and serve as a source of oxidative stress that activates platelets and renders them procoagulant. In testing this hypothesis experimentally, we found that the extracellular mitochondria purified from brain trauma mice and those released from brains subjected to freeze-thaw injury remained metabolically active and produced reactive oxygen species. These extracellular mitochondria bound platelets through the phospholipid-CD36 interaction and induced α-granule secretion, microvesiculation, and procoagulant activity in an oxidant-dependent manner, but failed to induce aggregation. These results define an extracellular mitochondria-induced and redox-dependent intermediate phenotype of platelets that contribute to the pathogenesis of traumatic brain injury-induced coagulopathy and inflammation.
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Affiliation(s)
- Zilong Zhao
- BloodWorks Research Institute, Seattle, WA, USA.,Tianjin Institute of Neurology, Departments of Neurosurgery and Neurology, Tianjin Medical University General Hospital, Tianjin, China
| | - Yuan Zhou
- BloodWorks Research Institute, Seattle, WA, USA.,Tianjin Institute of Neurology, Departments of Neurosurgery and Neurology, Tianjin Medical University General Hospital, Tianjin, China
| | | | - Fanjian Li
- Tianjin Institute of Neurology, Departments of Neurosurgery and Neurology, Tianjin Medical University General Hospital, Tianjin, China
| | - Cha Han
- BloodWorks Research Institute, Seattle, WA, USA
| | - Li Liu
- Tianjin Institute of Neurology, Departments of Neurosurgery and Neurology, Tianjin Medical University General Hospital, Tianjin, China
| | - Hengjie Yuan
- Tianjin Institute of Neurology, Departments of Neurosurgery and Neurology, Tianjin Medical University General Hospital, Tianjin, China
| | - Ying Li
- Tianjin Institute of Neurology, Departments of Neurosurgery and Neurology, Tianjin Medical University General Hospital, Tianjin, China
| | - Xin Xu
- BloodWorks Research Institute, Seattle, WA, USA
| | - Xiaoping Wu
- BloodWorks Research Institute, Seattle, WA, USA
| | - Fangyi Zhang
- Department of Neurosurgery, University of Washington School of Medicine, Seattle, WA, USA
| | - Perumal Thiagarajan
- Departments of Medicine and Pathology, Michael E. DeBakey VA Medical Center and Baylor College of Medicine, Houston, TX, USA
| | - Andrew Cap
- US Army Institute of Surgical Research, San Antonio, TX, USA
| | - Fu-Dong Shi
- Tianjin Institute of Neurology, Departments of Neurosurgery and Neurology, Tianjin Medical University General Hospital, Tianjin, China.,Department of Neurology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ, USA
| | - Jianning Zhang
- Tianjin Institute of Neurology, Departments of Neurosurgery and Neurology, Tianjin Medical University General Hospital, Tianjin, China
| | - Jing-Fei Dong
- BloodWorks Research Institute, Seattle, WA, USA .,Division of Hematology, Department of Medicine, University of Washington, School of Medicine, Seattle, WA, USA
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9
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Unsworth AJ, Bye AP, Tannetta DS, Desborough MJR, Kriek N, Sage T, Allan HE, Crescente M, Yaqoob P, Warner TD, Jones CI, Gibbins JM. Farnesoid X Receptor and Liver X Receptor Ligands Initiate Formation of Coated Platelets. Arterioscler Thromb Vasc Biol 2017; 37:1482-1493. [PMID: 28619996 PMCID: PMC5526435 DOI: 10.1161/atvbaha.117.309135] [Citation(s) in RCA: 15] [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: 01/30/2017] [Accepted: 05/30/2017] [Indexed: 12/20/2022]
Abstract
OBJECTIVES The liver X receptors (LXRs) and farnesoid X receptor (FXR) have been identified in human platelets. Ligands of these receptors have been shown to have nongenomic inhibitory effects on platelet activation by platelet agonists. This, however, seems contradictory with the platelet hyper-reactivity that is associated with several pathological conditions that are associated with increased circulating levels of molecules that are LXR and FXR ligands, such as hyperlipidemia, type 2 diabetes mellitus, and obesity. APPROACH AND RESULTS We, therefore, investigated whether ligands for the LXR and FXR receptors were capable of priming platelets to the activated state without stimulation by platelet agonists. Treatment of platelets with ligands for LXR and FXR converted platelets to the procoagulant state, with increases in phosphatidylserine exposure, platelet swelling, reduced membrane integrity, depolarization of the mitochondrial membrane, and microparticle release observed. Additionally, platelets also displayed features associated with coated platelets such as P-selectin exposure, fibrinogen binding, fibrin generation that is supported by increased serine protease activity, and inhibition of integrin αIIbβ3. LXR and FXR ligand-induced formation of coated platelets was found to be dependent on both reactive oxygen species and intracellular calcium mobilization, and for FXR ligands, this process was found to be dependent on cyclophilin D. CONCLUSIONS We conclude that treatment with LXR and FXR ligands initiates coated platelet formation, which is thought to support coagulation but results in desensitization to platelet stimuli through inhibition of αIIbβ3 consistent with their ability to inhibit platelet function and stable thrombus formation in vivo.
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Affiliation(s)
- Amanda J Unsworth
- From the Institute of Cardiovascular and Metabolic Research, School of Biological Sciences (A.J.U., A.P.B., N.K., T.S., M.C., C.I.J., J.M.G.) and Department of Food and Nutritional Sciences (D.S.T., P.Y.), University of Reading, United Kingdom; Oxford Haemophilia and Thrombosis Centre, Oxford Biomedical Research Centre, Churchill Hospital, United Kingdom (M.J.R.D.); Nuffield Division of Clinical Laboratory Sciences, University of Oxford, United Kingdom (M.J.R.D.); and Blizard Institute, Barts & the London School of Medicine & Dentistry, United Kingdom (H.E.A., M.C., T.D.W.)
| | - Alexander P Bye
- From the Institute of Cardiovascular and Metabolic Research, School of Biological Sciences (A.J.U., A.P.B., N.K., T.S., M.C., C.I.J., J.M.G.) and Department of Food and Nutritional Sciences (D.S.T., P.Y.), University of Reading, United Kingdom; Oxford Haemophilia and Thrombosis Centre, Oxford Biomedical Research Centre, Churchill Hospital, United Kingdom (M.J.R.D.); Nuffield Division of Clinical Laboratory Sciences, University of Oxford, United Kingdom (M.J.R.D.); and Blizard Institute, Barts & the London School of Medicine & Dentistry, United Kingdom (H.E.A., M.C., T.D.W.)
| | - Dionne S Tannetta
- From the Institute of Cardiovascular and Metabolic Research, School of Biological Sciences (A.J.U., A.P.B., N.K., T.S., M.C., C.I.J., J.M.G.) and Department of Food and Nutritional Sciences (D.S.T., P.Y.), University of Reading, United Kingdom; Oxford Haemophilia and Thrombosis Centre, Oxford Biomedical Research Centre, Churchill Hospital, United Kingdom (M.J.R.D.); Nuffield Division of Clinical Laboratory Sciences, University of Oxford, United Kingdom (M.J.R.D.); and Blizard Institute, Barts & the London School of Medicine & Dentistry, United Kingdom (H.E.A., M.C., T.D.W.)
| | - Michael J R Desborough
- From the Institute of Cardiovascular and Metabolic Research, School of Biological Sciences (A.J.U., A.P.B., N.K., T.S., M.C., C.I.J., J.M.G.) and Department of Food and Nutritional Sciences (D.S.T., P.Y.), University of Reading, United Kingdom; Oxford Haemophilia and Thrombosis Centre, Oxford Biomedical Research Centre, Churchill Hospital, United Kingdom (M.J.R.D.); Nuffield Division of Clinical Laboratory Sciences, University of Oxford, United Kingdom (M.J.R.D.); and Blizard Institute, Barts & the London School of Medicine & Dentistry, United Kingdom (H.E.A., M.C., T.D.W.)
| | - Neline Kriek
- From the Institute of Cardiovascular and Metabolic Research, School of Biological Sciences (A.J.U., A.P.B., N.K., T.S., M.C., C.I.J., J.M.G.) and Department of Food and Nutritional Sciences (D.S.T., P.Y.), University of Reading, United Kingdom; Oxford Haemophilia and Thrombosis Centre, Oxford Biomedical Research Centre, Churchill Hospital, United Kingdom (M.J.R.D.); Nuffield Division of Clinical Laboratory Sciences, University of Oxford, United Kingdom (M.J.R.D.); and Blizard Institute, Barts & the London School of Medicine & Dentistry, United Kingdom (H.E.A., M.C., T.D.W.)
| | - Tanya Sage
- From the Institute of Cardiovascular and Metabolic Research, School of Biological Sciences (A.J.U., A.P.B., N.K., T.S., M.C., C.I.J., J.M.G.) and Department of Food and Nutritional Sciences (D.S.T., P.Y.), University of Reading, United Kingdom; Oxford Haemophilia and Thrombosis Centre, Oxford Biomedical Research Centre, Churchill Hospital, United Kingdom (M.J.R.D.); Nuffield Division of Clinical Laboratory Sciences, University of Oxford, United Kingdom (M.J.R.D.); and Blizard Institute, Barts & the London School of Medicine & Dentistry, United Kingdom (H.E.A., M.C., T.D.W.)
| | - Harriet E Allan
- From the Institute of Cardiovascular and Metabolic Research, School of Biological Sciences (A.J.U., A.P.B., N.K., T.S., M.C., C.I.J., J.M.G.) and Department of Food and Nutritional Sciences (D.S.T., P.Y.), University of Reading, United Kingdom; Oxford Haemophilia and Thrombosis Centre, Oxford Biomedical Research Centre, Churchill Hospital, United Kingdom (M.J.R.D.); Nuffield Division of Clinical Laboratory Sciences, University of Oxford, United Kingdom (M.J.R.D.); and Blizard Institute, Barts & the London School of Medicine & Dentistry, United Kingdom (H.E.A., M.C., T.D.W.)
| | - Marilena Crescente
- From the Institute of Cardiovascular and Metabolic Research, School of Biological Sciences (A.J.U., A.P.B., N.K., T.S., M.C., C.I.J., J.M.G.) and Department of Food and Nutritional Sciences (D.S.T., P.Y.), University of Reading, United Kingdom; Oxford Haemophilia and Thrombosis Centre, Oxford Biomedical Research Centre, Churchill Hospital, United Kingdom (M.J.R.D.); Nuffield Division of Clinical Laboratory Sciences, University of Oxford, United Kingdom (M.J.R.D.); and Blizard Institute, Barts & the London School of Medicine & Dentistry, United Kingdom (H.E.A., M.C., T.D.W.)
| | - Parveen Yaqoob
- From the Institute of Cardiovascular and Metabolic Research, School of Biological Sciences (A.J.U., A.P.B., N.K., T.S., M.C., C.I.J., J.M.G.) and Department of Food and Nutritional Sciences (D.S.T., P.Y.), University of Reading, United Kingdom; Oxford Haemophilia and Thrombosis Centre, Oxford Biomedical Research Centre, Churchill Hospital, United Kingdom (M.J.R.D.); Nuffield Division of Clinical Laboratory Sciences, University of Oxford, United Kingdom (M.J.R.D.); and Blizard Institute, Barts & the London School of Medicine & Dentistry, United Kingdom (H.E.A., M.C., T.D.W.)
| | - Timothy D Warner
- From the Institute of Cardiovascular and Metabolic Research, School of Biological Sciences (A.J.U., A.P.B., N.K., T.S., M.C., C.I.J., J.M.G.) and Department of Food and Nutritional Sciences (D.S.T., P.Y.), University of Reading, United Kingdom; Oxford Haemophilia and Thrombosis Centre, Oxford Biomedical Research Centre, Churchill Hospital, United Kingdom (M.J.R.D.); Nuffield Division of Clinical Laboratory Sciences, University of Oxford, United Kingdom (M.J.R.D.); and Blizard Institute, Barts & the London School of Medicine & Dentistry, United Kingdom (H.E.A., M.C., T.D.W.)
| | - Chris I Jones
- From the Institute of Cardiovascular and Metabolic Research, School of Biological Sciences (A.J.U., A.P.B., N.K., T.S., M.C., C.I.J., J.M.G.) and Department of Food and Nutritional Sciences (D.S.T., P.Y.), University of Reading, United Kingdom; Oxford Haemophilia and Thrombosis Centre, Oxford Biomedical Research Centre, Churchill Hospital, United Kingdom (M.J.R.D.); Nuffield Division of Clinical Laboratory Sciences, University of Oxford, United Kingdom (M.J.R.D.); and Blizard Institute, Barts & the London School of Medicine & Dentistry, United Kingdom (H.E.A., M.C., T.D.W.)
| | - Jonathan M Gibbins
- From the Institute of Cardiovascular and Metabolic Research, School of Biological Sciences (A.J.U., A.P.B., N.K., T.S., M.C., C.I.J., J.M.G.) and Department of Food and Nutritional Sciences (D.S.T., P.Y.), University of Reading, United Kingdom; Oxford Haemophilia and Thrombosis Centre, Oxford Biomedical Research Centre, Churchill Hospital, United Kingdom (M.J.R.D.); Nuffield Division of Clinical Laboratory Sciences, University of Oxford, United Kingdom (M.J.R.D.); and Blizard Institute, Barts & the London School of Medicine & Dentistry, United Kingdom (H.E.A., M.C., T.D.W.).
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10
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Topalov NN, Yakimenko AO, Canault M, Artemenko EO, Zakharova NV, Abaeva AA, Loosveld M, Ataullakhanov FI, Nurden AT, Alessi MC, Panteleev MA. Two Types of Procoagulant Platelets Are Formed Upon Physiological Activation and Are Controlled by Integrin α
IIb
β
3. Arterioscler Thromb Vasc Biol 2012; 32:2475-83. [DOI: 10.1161/atvbaha.112.253765] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Objective—
Phosphatidylserine (PS) externalization by platelets upon activation is a key event in hemostasis and thrombosis. It is currently believed that strong stimulation of platelets forms 2 subpopulations, only 1 of which expresses PS.
Methods and Results—
Here, we demonstrate that physiological stimulation leads to the formation of not 1 but 2 types of PS-expressing activated platelets, with dramatically different properties. One subpopulation sustained increased calcium level after activation, whereas another returned to the basal low-calcium state. High-calcium PS-positive platelets had smaller size, high surface density of fibrin(ogen), no active integrin α
IIb
β
3
, depolarized mitochondrial membranes, gradually lost cytoplasmic membrane integrity, and were poorly aggregated. In contrast, the low-calcium PS-positive platelets had normal size, retained mitochondrial membrane potential and cytoplasmic membrane integrity, and combined retention of fibrin(ogen) with active α
IIb
β
3
and high proaggregatory function. Formation of low-calcium PS-positive platelets was promoted by platelet concentration increase or shaking and was decreased by integrin α
IIb
β
3
antagonists, platelet dilution, or in platelets from kindlin-3–deficient and Glanzmann thrombasthenia patients.
Conclusion—
Identification of a novel PS-expressing platelet subpopulation with low calcium regulated by integrin α
IIb
β
3
can be important for understanding the mechanisms of PS exposure and thrombus formation.
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Affiliation(s)
- Nikolay N. Topalov
- From the Center for Theoretical Problems of Physicochemical Pharmacology, Moscow, Russia (N.N.T., E.O.A., N.V.Z., A.A.A., F.I.A., M.A.P.); HemaCore LLC, Moscow, Russia (A.O.Y., F.I.A., M.A.P.); Université de la Méditerranée, Marseille Cedex, France (M.C., M.L., M-C.A.); INSERM Unité Mixte de Recherche, Marseille Cedex, France (M.C., M.L., M-C.A.); Laboratoire d’Hématologie, Hôpital de la Timone, Marseille Cedex, France (M.C., M.L., M-C.A.); National Research Centre for Hematology, Moscow, Russia (F
| | - Alena O. Yakimenko
- From the Center for Theoretical Problems of Physicochemical Pharmacology, Moscow, Russia (N.N.T., E.O.A., N.V.Z., A.A.A., F.I.A., M.A.P.); HemaCore LLC, Moscow, Russia (A.O.Y., F.I.A., M.A.P.); Université de la Méditerranée, Marseille Cedex, France (M.C., M.L., M-C.A.); INSERM Unité Mixte de Recherche, Marseille Cedex, France (M.C., M.L., M-C.A.); Laboratoire d’Hématologie, Hôpital de la Timone, Marseille Cedex, France (M.C., M.L., M-C.A.); National Research Centre for Hematology, Moscow, Russia (F
| | - Matthias Canault
- From the Center for Theoretical Problems of Physicochemical Pharmacology, Moscow, Russia (N.N.T., E.O.A., N.V.Z., A.A.A., F.I.A., M.A.P.); HemaCore LLC, Moscow, Russia (A.O.Y., F.I.A., M.A.P.); Université de la Méditerranée, Marseille Cedex, France (M.C., M.L., M-C.A.); INSERM Unité Mixte de Recherche, Marseille Cedex, France (M.C., M.L., M-C.A.); Laboratoire d’Hématologie, Hôpital de la Timone, Marseille Cedex, France (M.C., M.L., M-C.A.); National Research Centre for Hematology, Moscow, Russia (F
| | - Elena O. Artemenko
- From the Center for Theoretical Problems of Physicochemical Pharmacology, Moscow, Russia (N.N.T., E.O.A., N.V.Z., A.A.A., F.I.A., M.A.P.); HemaCore LLC, Moscow, Russia (A.O.Y., F.I.A., M.A.P.); Université de la Méditerranée, Marseille Cedex, France (M.C., M.L., M-C.A.); INSERM Unité Mixte de Recherche, Marseille Cedex, France (M.C., M.L., M-C.A.); Laboratoire d’Hématologie, Hôpital de la Timone, Marseille Cedex, France (M.C., M.L., M-C.A.); National Research Centre for Hematology, Moscow, Russia (F
| | - Natalia V. Zakharova
- From the Center for Theoretical Problems of Physicochemical Pharmacology, Moscow, Russia (N.N.T., E.O.A., N.V.Z., A.A.A., F.I.A., M.A.P.); HemaCore LLC, Moscow, Russia (A.O.Y., F.I.A., M.A.P.); Université de la Méditerranée, Marseille Cedex, France (M.C., M.L., M-C.A.); INSERM Unité Mixte de Recherche, Marseille Cedex, France (M.C., M.L., M-C.A.); Laboratoire d’Hématologie, Hôpital de la Timone, Marseille Cedex, France (M.C., M.L., M-C.A.); National Research Centre for Hematology, Moscow, Russia (F
| | - Anastasia A. Abaeva
- From the Center for Theoretical Problems of Physicochemical Pharmacology, Moscow, Russia (N.N.T., E.O.A., N.V.Z., A.A.A., F.I.A., M.A.P.); HemaCore LLC, Moscow, Russia (A.O.Y., F.I.A., M.A.P.); Université de la Méditerranée, Marseille Cedex, France (M.C., M.L., M-C.A.); INSERM Unité Mixte de Recherche, Marseille Cedex, France (M.C., M.L., M-C.A.); Laboratoire d’Hématologie, Hôpital de la Timone, Marseille Cedex, France (M.C., M.L., M-C.A.); National Research Centre for Hematology, Moscow, Russia (F
| | - Marie Loosveld
- From the Center for Theoretical Problems of Physicochemical Pharmacology, Moscow, Russia (N.N.T., E.O.A., N.V.Z., A.A.A., F.I.A., M.A.P.); HemaCore LLC, Moscow, Russia (A.O.Y., F.I.A., M.A.P.); Université de la Méditerranée, Marseille Cedex, France (M.C., M.L., M-C.A.); INSERM Unité Mixte de Recherche, Marseille Cedex, France (M.C., M.L., M-C.A.); Laboratoire d’Hématologie, Hôpital de la Timone, Marseille Cedex, France (M.C., M.L., M-C.A.); National Research Centre for Hematology, Moscow, Russia (F
| | - Fazoil I. Ataullakhanov
- From the Center for Theoretical Problems of Physicochemical Pharmacology, Moscow, Russia (N.N.T., E.O.A., N.V.Z., A.A.A., F.I.A., M.A.P.); HemaCore LLC, Moscow, Russia (A.O.Y., F.I.A., M.A.P.); Université de la Méditerranée, Marseille Cedex, France (M.C., M.L., M-C.A.); INSERM Unité Mixte de Recherche, Marseille Cedex, France (M.C., M.L., M-C.A.); Laboratoire d’Hématologie, Hôpital de la Timone, Marseille Cedex, France (M.C., M.L., M-C.A.); National Research Centre for Hematology, Moscow, Russia (F
| | - Alan T. Nurden
- From the Center for Theoretical Problems of Physicochemical Pharmacology, Moscow, Russia (N.N.T., E.O.A., N.V.Z., A.A.A., F.I.A., M.A.P.); HemaCore LLC, Moscow, Russia (A.O.Y., F.I.A., M.A.P.); Université de la Méditerranée, Marseille Cedex, France (M.C., M.L., M-C.A.); INSERM Unité Mixte de Recherche, Marseille Cedex, France (M.C., M.L., M-C.A.); Laboratoire d’Hématologie, Hôpital de la Timone, Marseille Cedex, France (M.C., M.L., M-C.A.); National Research Centre for Hematology, Moscow, Russia (F
| | - Marie-Christine Alessi
- From the Center for Theoretical Problems of Physicochemical Pharmacology, Moscow, Russia (N.N.T., E.O.A., N.V.Z., A.A.A., F.I.A., M.A.P.); HemaCore LLC, Moscow, Russia (A.O.Y., F.I.A., M.A.P.); Université de la Méditerranée, Marseille Cedex, France (M.C., M.L., M-C.A.); INSERM Unité Mixte de Recherche, Marseille Cedex, France (M.C., M.L., M-C.A.); Laboratoire d’Hématologie, Hôpital de la Timone, Marseille Cedex, France (M.C., M.L., M-C.A.); National Research Centre for Hematology, Moscow, Russia (F
| | - Mikhail A. Panteleev
- From the Center for Theoretical Problems of Physicochemical Pharmacology, Moscow, Russia (N.N.T., E.O.A., N.V.Z., A.A.A., F.I.A., M.A.P.); HemaCore LLC, Moscow, Russia (A.O.Y., F.I.A., M.A.P.); Université de la Méditerranée, Marseille Cedex, France (M.C., M.L., M-C.A.); INSERM Unité Mixte de Recherche, Marseille Cedex, France (M.C., M.L., M-C.A.); Laboratoire d’Hématologie, Hôpital de la Timone, Marseille Cedex, France (M.C., M.L., M-C.A.); National Research Centre for Hematology, Moscow, Russia (F
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11
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Topalov NN, Kotova YN, Vasil’ev SA, Panteleev MA. Identification of signal transduction pathways involved in the formation of platelet subpopulations upon activation. Br J Haematol 2012; 157:105-15. [DOI: 10.1111/j.1365-2141.2011.09021.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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12
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Knudsen T, Kjalke M, Tranholm M, Nichols TC, Jensen AL, Kristensen AT. Development of a flow cytometric assay for detection of coated platelets in dogs and evaluation of binding of coated platelets to recombinant human coagulation factor VIIa. Am J Vet Res 2011; 72:1007-14. [DOI: 10.2460/ajvr.72.8.1007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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13
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Dale GL, Remenyi G, Friese P. Tetraspanin CD9 is required for microparticle release from coated-platelets. Platelets 2010; 20:361-6. [PMID: 19658001 DOI: 10.1080/09537100903096692] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
CD9, a member of the tetraspanin superfamily, is the third most abundant protein on the platelet surface, but its function remains unknown. In this report, we demonstrate that CD9 is required for the release of microparticles from coated-platelets. Coated-platelets are formed as a result of dual agonist activation with collagen and thrombin, and each coated-platelet releases 15-25 microparticles averaging 0.4 microm in diameter. We report here that four separate monoclonal antibodies against CD9 inhibited microparticle release from coated-platelets by 72-102% with an IC(50) of approximately 500 ng/mL for ALB6 and SN4. In addition, the anti-alpha(IIb)beta(3) monoclonal antibody AP2 also inhibited microparticle release although additional anti-alpha(IIb)beta(3) monoclonals did not. These data support participation of the tetraspanin CD9, together with the integrin alpha(IIb)beta(3), in the membrane vesiculation process associated with platelet microparticle release.
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Affiliation(s)
- George L Dale
- Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma, OK 73104, USA.
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14
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Valaydon ZS, Lee P, Dale GL, Januszewski AS, Rowley KG, Nandurkar H, Karschimkus C, Best JD, Lyons TJ, Jenkins AJ. Increased coated-platelet levels in chronic haemodialysis patients. Nephrology (Carlton) 2009; 14:148-54. [PMID: 19076292 DOI: 10.1111/j.1440-1797.2008.01026.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
AIM To determine if levels of coated-platelets, which are potentially pro-thrombotic, are increased in end-stage renal disease patients on haemodialysis, a condition associated with high cardiovascular disease risk. METHODS In a cross-sectional observational study, coated-platelet levels were measured by flow cytometry in 25 end-stage renal failure haemodialysis patients and 25 controls without renal disease. Associations between coated-platelet levels and clinical and biochemical factors relevant to renal and cardiovascular disease were evaluated. RESULTS Mean +/- SD coated-platelet levels were higher in the dialysis group than in the control group (39.3+/-14.3% vs 30.9+/-10.3%, P=0.02). The number of subjects with high coated-platelet levels (>40%) was larger in the dialysis than in the control group (13/25 vs 4/25, chi(2) test, P=0.007). On univariate analysis, coated-platelet levels correlated with serum C-reactive protein levels in renal failure (r=0.47, P=0.02) and inversely with white cell count in the control group (r= -0.60, P=0.001). Coated-platelet levels were higher in dialysis patients reporting alcohol abstinence than among those reporting 'social' drinking (44.3+/-12.6 vs 28.8+/-13.5%, P=0.01). Age, gender, body weight, smoking, diabetes, lipid levels and lipid-lowering drugs were not associated with coated-platelet levels (all P>0.05). CONCLUSION Coated-platelet levels are increased in haemodialysis patients relative to subjects with normal renal function, and are related to inflammation and alcohol abstinence. Other vascular risk factors, such as smoking, lipids and diabetes, were not related to coated-platelet levels. Coated-platelets may be implicated in the increased thrombosis and vascular risk in end-stage renal disease.
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Affiliation(s)
- Zina S Valaydon
- Department of Medicine, St Vincent's Hospital, The University of Melbourne, Melbourne, Australia
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15
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Prodan CI, Joseph PM, Vincent AS, Dale GL. Coated-platelets in ischemic stroke: differences between lacunar and cortical stroke. J Thromb Haemost 2008; 6:609-14. [PMID: 18182039 DOI: 10.1111/j.1538-7836.2008.02890.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND Coated-platelets are a subset of platelets with procoagulant potential observed upon dual agonist stimulation with collagen and thrombin. OBJECTIVE The goal was to investigate if coated-platelet production differs between patients with lacunar ischemic stroke and non-lacunar (cortical) ischemic stroke as compared with controls. PATIENTS AND METHODS Blood samples from 60 patients with ischemic stroke (20 lacunar and 40 cortical) and 70 controls were analyzed for coated-platelet production. RESULTS Coated-platelet production was significantly lower in patients with lacunar stroke (21.8 +/- 11.4%, mean +/- 1 SD) as compared with either controls (31.6 +/- 13.2%, P = 0.008) or patients with cortical stroke (39.4 +/- 12.7%, P < 0.001). The increase in coated-platelets for patients with cortical stroke as compared with controls was also significant (P = 0.008). CONCLUSIONS Our results indicate a marked difference in coated-platelet synthesis in lacunar vs. non-lacunar stroke, thereby providing additional support for the existence of distinct pathological processes underlying these two subtypes of ischemic stroke. Further investigation of the role of coated-platelets in stroke, taking into account these preliminary findings, is warranted.
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Affiliation(s)
- C I Prodan
- VA Medical Center, Oklahoma City, OK, USA.
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16
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Serebruany V, Malinin A, Pokov A, Arora U, Atar D, Angiolillo D. Effects of escalating doses of tirofiban on platelet aggregation and major receptor expression in diabetic patients: Hitting the TARGET in the TENACITY trial? Thromb Res 2007; 119:175-81. [PMID: 16546241 DOI: 10.1016/j.thromres.2006.02.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2005] [Revised: 02/06/2006] [Accepted: 02/07/2006] [Indexed: 11/20/2022]
Abstract
INTRODUCTION Ongoing search for the optimal dosing regimens, and valid concerns that some GPIIb/IIIa inhibitors may cause rebound platelet activation are limiting the use of these agents in patients with acute vascular events. MATERIALS AND METHODS We assessed the in vitro effects of preincubation with escalating (12.5-200 ng/mL) concentrations of tirofiban on platelet biomarkers in 20 diabetic patients. Platelet activity was assessed by ADP-, and collagen-induced conventional plasma aggregometry, and by whole blood flow cytometry measuring expression of PECAM-1, GPIb, GP IIb/IIIa antigen and activity, vitronectin, P-selectin, LAMP-1, GP 37, LAMP-3, activated and intact PAR-1 thrombin receptors, GPIV, and platelet-monocyte formation. All patients were treated with aspirin (at least 81 mg daily for 1 month); other antiplatelet agents were not allowed. RESULTS Significant decrease of ADP-induced platelet aggregation was observed starting at the low 12.5 ng/mL concentration (p=0.0001), with total inhibition occurring at 50 ng/mL of tirofiban dose. Inhibition of collagen-induced platelet aggregability requires 25 ng/ml of tirofiban (p=0.002), and was complete at 100 ng/mL. Dose-dependent blockade of GP IIb/IIIa activity was observed with tirofiban concentrations over 50 ng/mL (p=0.003). Other receptors were unaffected even with the high doses of tirofiban (100-200 ng/mL). CONCLUSION Tirofiban completely inhibits ADP- and, with the higher dose, collagen-induced platelet aggregation. Higher loading dose of tirofiban used in the ongoing TENACITY trial (100 ng/mL) may be superior with regard to clinical outcomes to the regimens used in PRISM-PLUS (25 ng/mL), or TARGET (50 ng/mL). Selective inhibition of GPIIb/IIIa activity, and lack of alternative platelet activation beyond the GP IIb/IIIa blockade may represent the therapeutic advantage of tirofiban over other agents.
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Affiliation(s)
- Victor Serebruany
- HeartDrug Research Laboratories, Johns Hopkins University, Baltimore, 7600 Osler Drive, Suite 307, Towson, Maryland 21204, USA.
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17
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Abstract
Coated-platelets, formerly known as COAT-platelets, represent a subpopulation of cells observed after dual agonist stimulation of platelets with collagen and thrombin. This class of platelets retains on its surface high levels of several procoagulant proteins, including fibrinogen, von Willebrand factor, fibronectin, factor V and thrombospondin. Coated-platelets also express surface phosphatidylserine and strongly support prothrombinase activity. Retention of alpha-granule proteins on the surface of coated-platelets involves an unexpected derivatization of these proteins with serotonin and an interaction of serotonin-conjugated proteins with serotonin binding sites on fibrinogen and thrombospondin. This review will also detail experimental systems where coated-platelets are generated as a result of other agonist(s). Finally, the putative physiological consequences of coated-platelet formation will be discussed.
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Affiliation(s)
- G L Dale
- W.K. Warren Medical Research Institute, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
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