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Gantseva AR, Gantseva ER, Sveshnikova AN, Panteleev MA, Kovalenko TA. Kinetic analysis of prothrombinase assembly and substrate delivery mechanisms. J Theor Biol 2024; 594:111925. [PMID: 39142600 DOI: 10.1016/j.jtbi.2024.111925] [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: 05/23/2024] [Revised: 08/01/2024] [Accepted: 08/02/2024] [Indexed: 08/16/2024]
Abstract
Prothrombinase complex, composed of coagulation factors Xa (FXa) and Va (FVa) is a major enzyme of the blood coagulation network that produces thrombin via activation of its inactive precursor prothrombin (FII) on the surface of phospholipid membranes. However, pathways and mechanisms of prothrombinase formation and substrate delivery are still discussed. Here we designed a novel mathematical model that considered different potential pathways of FXa or FII binding (from the membrane or from solution) and analyzed the kinetics of thrombin formation in the presence of a wide range of reactants concentrations. We observed the inhibitory effect of large FVa concentrations and this effect was phospholipid concentration-dependent. We predicted that efficient FII activation occurred via formation of the ternary complex, in which FVa, FXa and FII were in the membrane-bound state. Prothrombin delivery was mostly membrane-dependent, but delivery from solution was predominant under conditions of phospholipid deficiency or FXa/FVa excess. Likewise, FXa delivery from solution was predominant in the case of FVa excess, but high FII did not switch the FXa delivery to the solution-dependent one. Additionally, the FXa delivery pathway did not depend on the phospholipid concentration, being the membrane-dependent one even in case of the phospholipid deficiency. These results suggest a flexible mechanism of prothrombinase functioning which utilizes different complex formation and even inhibitory mechanisms depending on conditions.
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Affiliation(s)
- A R Gantseva
- Department of Biological and Medical Physics, Moscow Institute of Physics and Technology, Institutskiy Pereulok, 9, Dolgoprudny, Moscow Oblast 141701, Russia
| | - E R Gantseva
- Faculty of Physics, Lomonosov Moscow State University, 1/2 Leninskie gory, Moscow 119991, Russia
| | - A N Sveshnikova
- Center for Theoretical Problems of Physico-Chemical Pharmacology, Russian Academy of Sciences, 30 Srednyaya Kalitnikovskaya str., Moscow 109029, Russia; National Medical Research Centre of Pediatric Hematology, Oncology and Immunology named after Dmitry Rogachev, 1 Samory Mashela St, 117198 Moscow, Russia; Faculty of Fundamental Physical and Chemical Engineering, Lomonosov Moscow State University, GSP-1, 1 Leninskiye Gory, Moscow 119991, Russia
| | - M A Panteleev
- Faculty of Physics, Lomonosov Moscow State University, 1/2 Leninskie gory, Moscow 119991, Russia; Center for Theoretical Problems of Physico-Chemical Pharmacology, Russian Academy of Sciences, 30 Srednyaya Kalitnikovskaya str., Moscow 109029, Russia; National Medical Research Centre of Pediatric Hematology, Oncology and Immunology named after Dmitry Rogachev, 1 Samory Mashela St, 117198 Moscow, Russia
| | - T A Kovalenko
- Center for Theoretical Problems of Physico-Chemical Pharmacology, Russian Academy of Sciences, 30 Srednyaya Kalitnikovskaya str., Moscow 109029, Russia; National Medical Research Centre of Pediatric Hematology, Oncology and Immunology named after Dmitry Rogachev, 1 Samory Mashela St, 117198 Moscow, Russia.
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Jewell MP, Ashour Z, Baird CH, Manco Johnson M, Warren BB, Wufsus AR, Pallini C, Dockal M, Kjalke M, Neeves KB. Concizumab improves clot formation in hemophilia A under flow. J Thromb Haemost 2024; 22:2438-2448. [PMID: 38815755 PMCID: PMC11343664 DOI: 10.1016/j.jtha.2024.05.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Revised: 05/01/2024] [Accepted: 05/15/2024] [Indexed: 06/01/2024]
Abstract
BACKGROUND Inhibition of tissue factor pathway inhibitor (TFPI) is an emerging therapeutic strategy for treatment of hemophilia. Concizumab is a monoclonal antibody that binds TFPI and blocks its inhibition of factor (F)Xa thereby extending the initiation of coagulation and compensating for lack of FVIII or FIX. OBJECTIVES The objective of this in vitro study was to evaluate how concizumab affects clot formation in hemophilia A under flow. METHODS Blood was collected from normal controls or people with hemophilia A. An anti-FVIII antibody was added to normal controls to simulate hemophilia A with inhibitory antibodies to FVIII. Whole blood and recombinant activated FVII (rFVIIa, 25 nM) or concizumab (200, 1000, and 4000 ng/mL) were perfused at 100 s-1 over a surface micropatterned with tissue factor (TF) and collagen-related peptide. Platelet and fibrin(ogen) accumulation were measured by confocal microscopy. Static thrombin generation in plasma was measured in response to rFVIIa and concizumab. RESULTS Concizumab (1000 and 4000 ng/mL) and rFVIIa both rescued (93%-101%) total platelet accumulation, but only partially rescued (53%-63%) fibrin(ogen) incorporation to normal control levels in simulated hemophilia A. Results using congenital hemophilia A blood confirmed effects of rFVIIa and concizumab. While these 2 agents had similar effect on clot formation under flow, concizumab enhanced thrombin generation in plasma under static conditions to a greater extent than rFVIIa. CONCLUSION TFPI inhibition by concizumab enhanced activation and aggregation of platelets and fibrin clot formation in hemophilia A to levels comparable with that of rFVIIa.
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Affiliation(s)
- Megan P Jewell
- Department of Bioengineering, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado, USA
| | - Zaina Ashour
- Department of Bioengineering, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado, USA
| | - Christine H Baird
- Department of Pediatrics, Section of Hematology, Oncology, and Bone Marrow Transplant, University of Colorado, Anschutz Medical Campus, Aurora, Colorado, USA; Hemophilia and Thrombosis Center, University of Colorado, Anschutz Medical Campus, Aurora, Colorado, USA
| | - Marilyn Manco Johnson
- Department of Pediatrics, Section of Hematology, Oncology, and Bone Marrow Transplant, University of Colorado, Anschutz Medical Campus, Aurora, Colorado, USA; Hemophilia and Thrombosis Center, University of Colorado, Anschutz Medical Campus, Aurora, Colorado, USA
| | - Beth Boulden Warren
- Department of Pediatrics, Section of Hematology, Oncology, and Bone Marrow Transplant, University of Colorado, Anschutz Medical Campus, Aurora, Colorado, USA; Hemophilia and Thrombosis Center, University of Colorado, Anschutz Medical Campus, Aurora, Colorado, USA
| | - Adam R Wufsus
- Rare Blood Disorders, Medical Affairs Rare Disease, Novo Nordisk Inc, Plainsboro, New Jersey, USA
| | - Chiara Pallini
- Rare Blood Disorders, Rare Disease Research, Novo Nordisk, Måløv, Denmark
| | - Michael Dockal
- Rare Blood Disorders, Rare Disease Research, Novo Nordisk, Måløv, Denmark
| | - Marianne Kjalke
- Rare Blood Disorders, Rare Disease Research, Novo Nordisk, Måløv, Denmark
| | - Keith B Neeves
- Department of Bioengineering, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado, USA; Department of Pediatrics, Section of Hematology, Oncology, and Bone Marrow Transplant, University of Colorado, Anschutz Medical Campus, Aurora, Colorado, USA; Hemophilia and Thrombosis Center, University of Colorado, Anschutz Medical Campus, Aurora, Colorado, USA.
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Sveshnikova AN, Shibeko AM, Kovalenko TA, Panteleev MA. Kinetics and regulation of coagulation factor X activation by intrinsic tenase on phospholipid membranes. J Theor Biol 2024; 582:111757. [PMID: 38336240 DOI: 10.1016/j.jtbi.2024.111757] [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: 08/28/2023] [Revised: 12/13/2023] [Accepted: 01/31/2024] [Indexed: 02/12/2024]
Abstract
BACKGROUND Factor X activation by the phospholipid-bound intrinsic tenase complex is a critical membrane-dependent reaction of blood coagulation. Its regulation mechanisms are unclear, and a number of questions regarding diffusional limitation, pathways of assembly and substrate delivery remain open. METHODS We develop and analyze here a detailed mechanism-driven computer model of intrinsic tenase on phospholipid surfaces. Three-dimensional reaction-diffusion-advection and stochastic simulations were used where appropriate. RESULTS Dynamics of the system was predominantly non-stationary under physiological conditions. In order to describe experimental data, we had to assume both membrane-dependent and solution-dependent delivery of the substrate. The former pathway dominated at low cofactor concentration, while the latter became important at low phospholipid concentration. Factor VIIIa-factor X complex formation was the major pathway of the complex assembly, and the model predicted high affinity for their lipid-dependent interaction. Although the model predicted formation of the diffusion-limited layer of substrate for some conditions, the effects of this limitation on the fXa production were small. Flow accelerated fXa production in a flow reactor model by bringing in fIXa and fVIIIa rather than fX. CONCLUSIONS This analysis suggests a concept of intrinsic tenase that is non-stationary, employs several pathways of substrate delivery depending on the conditions, and is not particularly limited by diffusion of the substrate.
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Affiliation(s)
- Anastasia N Sveshnikova
- National Medical and Research Center of Pediatric Hematology, Oncology and Immunology Named After Dmitry Rogachev, 1 Samory Mashela St, Moscow, 117198, Russia; Faculty of Fundamental Physico-Chemical Engineering, Lomonosov Moscow State University, 1/51 Leninskie Gory, 119991 Moscow, Russia; Department of Normal Physiology, Sechenov First Moscow State Medical University, 8/2 Trubetskaya St., 119991 Moscow, Russia; Center for Theoretical Problems of Physicochemical Pharmacology, Russian Academy of Sciences, 4 Kosygina St, Moscow, 119991, Russia
| | - Alexey M Shibeko
- National Medical and Research Center of Pediatric Hematology, Oncology and Immunology Named After Dmitry Rogachev, 1 Samory Mashela St, Moscow, 117198, Russia; Center for Theoretical Problems of Physicochemical Pharmacology, Russian Academy of Sciences, 4 Kosygina St, Moscow, 119991, Russia
| | - Tatiana A Kovalenko
- National Medical and Research Center of Pediatric Hematology, Oncology and Immunology Named After Dmitry Rogachev, 1 Samory Mashela St, Moscow, 117198, Russia; Center for Theoretical Problems of Physicochemical Pharmacology, Russian Academy of Sciences, 4 Kosygina St, Moscow, 119991, Russia
| | - Mikhail A Panteleev
- National Medical and Research Center of Pediatric Hematology, Oncology and Immunology Named After Dmitry Rogachev, 1 Samory Mashela St, Moscow, 117198, Russia; Center for Theoretical Problems of Physicochemical Pharmacology, Russian Academy of Sciences, 4 Kosygina St, Moscow, 119991, Russia; Faculty of Physics, Lomonosov Moscow State University, 1/2 Leninskie Gory, Moscow, 119991, Russia.
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Kovalenko TA, Panteleev MA, Sveshnikova AN. Different modeling approaches in the simulation of extrinsic coagulation factor X activation: Limitations and areas of applicability. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2023; 39:e3689. [PMID: 36802118 DOI: 10.1002/cnm.3689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 01/16/2023] [Accepted: 02/07/2023] [Indexed: 06/18/2023]
Abstract
Proteolytic reactions on the phospholipid membrane surface, so-called "membrane-dependent" reactions, play central role in the process of blood clotting. One particularly important example is FX activation by the extrinsic tenase (VIIa/TF). Here we constructed three mathematical models of FX activation by VIIa/TF: (A) a homogeneous "well-mixed" model, (B) a two-compartment "well-mixed" model, (C) a heterogeneous model with diffusion, to investigate the impact and importance of inclusion of each complexity level. All models provided good description of the reported experimental data and were equivalently applicable for <40 μM of phospholipids. Model C provided better predictions than A, B in the presence of TF-negative phospholipid microparticles. Models predicted that for high TF surface density (STF ) and FX deficiency the FX activation rate was limited by the rate of FX binding to the membrane. For low STF and excess of FX the reaction rate was limited by the tenase formation rate. The analysis of the substrate delivery pathways revealed that FX bound to VIIa/TF predominantly from solution for STF >2.8 × 10-3 nmol/cm2 and from the membrane for lower STF . We proposed the experimental setting to distinguish between the collision-limited and non-collision-limited binding. The analysis of models in flow and non-flow conditions revealed that the model of a vesicle in flow might be substituted by model C in the absence of the substrate depletion. Together, this study was the first which provided the direct comparison of more simple and more complex models. The reaction mechanisms were studied in a wide range of conditions.
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Affiliation(s)
- Tatiana A Kovalenko
- Center for Theoretical Problems of Physico-Chemical Pharmacology, Russian Academy of Sciences, Moscow, Russia
- National Medical Research Centre of Pediatric Hematology, Oncology and Immunology named after Dmitry Rogachev, Moscow, Russia
| | - Mikhail A Panteleev
- Center for Theoretical Problems of Physico-Chemical Pharmacology, Russian Academy of Sciences, Moscow, Russia
- National Medical Research Centre of Pediatric Hematology, Oncology and Immunology named after Dmitry Rogachev, Moscow, Russia
- Faculty of Physics, Lomonosov Moscow State University, Moscow, Russia
| | - Anastasia N Sveshnikova
- Center for Theoretical Problems of Physico-Chemical Pharmacology, Russian Academy of Sciences, Moscow, Russia
- National Medical Research Centre of Pediatric Hematology, Oncology and Immunology named after Dmitry Rogachev, Moscow, Russia
- Faculty of Fundamental Physical and Chemical Engineering, Lomonosov Moscow State University, Moscow, Russia
- Department of Normal Physiology, Sechenov First Moscow State Medical University, Moscow, Russia
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Modeling thrombosis in silico: Frontiers, challenges, unresolved problems and milestones. Phys Life Rev 2018; 26-27:57-95. [PMID: 29550179 DOI: 10.1016/j.plrev.2018.02.005] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Revised: 02/21/2018] [Accepted: 02/24/2018] [Indexed: 12/24/2022]
Abstract
Hemostasis is a complex physiological mechanism that functions to maintain vascular integrity under any conditions. Its primary components are blood platelets and a coagulation network that interact to form the hemostatic plug, a combination of cell aggregate and gelatinous fibrin clot that stops bleeding upon vascular injury. Disorders of hemostasis result in bleeding or thrombosis, and are the major immediate cause of mortality and morbidity in the world. Regulation of hemostasis and thrombosis is immensely complex, as it depends on blood cell adhesion and mechanics, hydrodynamics and mass transport of various species, huge signal transduction networks in platelets, as well as spatiotemporal regulation of the blood coagulation network. Mathematical and computational modeling has been increasingly used to gain insight into this complexity over the last 30 years, but the limitations of the existing models remain profound. Here we review state-of-the-art-methods for computational modeling of thrombosis with the specific focus on the analysis of unresolved challenges. They include: a) fundamental issues related to physics of platelet aggregates and fibrin gels; b) computational challenges and limitations for solution of the models that combine cell adhesion, hydrodynamics and chemistry; c) biological mysteries and unknown parameters of processes; d) biophysical complexities of the spatiotemporal networks' regulation. Both relatively classical approaches and innovative computational techniques for their solution are considered; the subjects discussed with relation to thrombosis modeling include coarse-graining, continuum versus particle-based modeling, multiscale models, hybrid models, parameter estimation and others. Fundamental understanding gained from theoretical models are highlighted and a description of future prospects in the field and the nearest possible aims are given.
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Haynes LM, Orfeo T, Mann KG, Everse SJ, Brummel-Ziedins KE. Probing the Dynamics of Clot-Bound Thrombin at Venous Shear Rates. Biophys J 2017; 112:1634-1644. [PMID: 28445754 DOI: 10.1016/j.bpj.2017.03.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Revised: 02/28/2017] [Accepted: 03/01/2017] [Indexed: 02/07/2023] Open
Abstract
In closed system models of fibrin formation, exosite-mediated thrombin binding to fibrin contributes to clot stability and is resistant to inhibition by antithrombin/heparin while still susceptible to small, active-site inhibitors. Each molecule of fibrin can bind ∼1.6 thrombin molecules at low-affinity binding sites (Kd = 2.8 μM) and ∼0.3 molecules of thrombin at high-affinity binding sites (Kd = 0.15 μM). The goal of this study is to assess the stability of fibrin-bound thrombin under venous flow conditions and to determine both its accessibility and susceptibility to inhibition. A parallel-plate flow chamber (7 × 50 × 0.25 mm) for studying the stability of thrombin (0-1400 nM) adhered to a fibrin matrix (0.1-0.4 mg/mL fibrinogen, 10 nM thrombin) under a variety of venous flow conditions was developed using the thrombin-specific, fluorogenic substrate SN-59 (100 μM). The flow within this system is laminar (Re < 1) and reaction rates are driven by enzyme kinetics (Pe = 100, Da = 7000). A subpopulation of active thrombin remains stably adhered to a fibrin matrix over a range of venous shear rates (46-184 s-1) for upwards of 30 min, and this population is saturable at loads >500 nM and sensitive to the initial fibrinogen concentration. These observations were also supported by a mathematical model of thrombin adhesion to fibrin, which demonstrates that thrombin initially binds to the low-affinity thrombin binding sites before preferentially equilibrating to higher affinity sites. Antithrombin (2.6 μM) plus heparin (4 U/mL) inhibits 72% of the active clot-bound thrombin after ∼10 min at 92 s-1, while no inhibition is observed in the absence of heparin. Dabigatran (20 and 200 nM) inhibits (50 and 93%) clot-bound thrombin reversibly (87 and 66% recovery). This model illustrates that clot-bound thrombin stability is the result of a constant rearrangement of thrombin molecules within a dense matrix of binding sites.
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Affiliation(s)
- Laura M Haynes
- Department of Biochemistry, Robert Larner M.D. College of Medicine, University of Vermont, Colchester, Vermont
| | - Thomas Orfeo
- Department of Biochemistry, Robert Larner M.D. College of Medicine, University of Vermont, Colchester, Vermont
| | | | - Stephen J Everse
- Department of Biochemistry, Robert Larner M.D. College of Medicine, University of Vermont, Colchester, Vermont
| | - Kathleen E Brummel-Ziedins
- Department of Biochemistry, Robert Larner M.D. College of Medicine, University of Vermont, Colchester, Vermont.
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Rana K, Neeves KB. Blood flow and mass transfer regulation of coagulation. Blood Rev 2016; 30:357-68. [PMID: 27133256 DOI: 10.1016/j.blre.2016.04.004] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Revised: 02/17/2016] [Accepted: 04/12/2016] [Indexed: 12/12/2022]
Abstract
Blood flow regulates coagulation and fibrin formation by controlling the transport, or mass transfer, of zymogens, co-factors, enzymes, and inhibitors to, from, and within a growing thrombus. The rate of mass transfer of these solutes relative to their consumption or production by coagulation reactions determines, in part, the rate of thrombin generation, fibrin deposition, and thrombi growth. Experimental studies on the influence of blood flow on specific coagulation reactions are reviewed here, along with a theoretical framework that predicts how flow influences surface-bound coagulation binding and enzymatic reactions. These flow-mediated transport mechanisms are also used to interpret the role of binding site densities and injury size on initiating coagulation and fibrin deposition. The importance of transport of coagulation proteins within the interstitial spaces of thrombi is shown to influence thrombi architecture, growth, and arrest.
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Affiliation(s)
- Kuldeepsinh Rana
- Chemical and Biological Engineering, Colorado School of Mines, Golden, CO, USA
| | - Keith B Neeves
- Chemical and Biological Engineering, Colorado School of Mines, Golden, CO, USA; Pediatrics, University of Colorado-Denver, Aurora, CO, USA.
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Panteleev MA, Dashkevich NM, Ataullakhanov FI. Hemostasis and thrombosis beyond biochemistry: roles of geometry, flow and diffusion. Thromb Res 2015; 136:699-711. [DOI: 10.1016/j.thromres.2015.07.025] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Revised: 07/22/2015] [Accepted: 07/26/2015] [Indexed: 11/16/2022]
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Leiderman K, Fogelson A. An overview of mathematical modeling of thrombus formation under flow. Thromb Res 2014; 133 Suppl 1:S12-4. [DOI: 10.1016/j.thromres.2014.03.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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10
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Larson MK, Tormoen GW, Weaver LJ, Luepke KJ, Patel IA, Hjelmen CE, Ensz NM, McComas LS, McCarty OJT. Exogenous modification of platelet membranes with the omega-3 fatty acids EPA and DHA reduces platelet procoagulant activity and thrombus formation. Am J Physiol Cell Physiol 2012; 304:C273-9. [PMID: 23174566 DOI: 10.1152/ajpcell.00174.2012] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Several studies have implicated the omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in inhibition of normal platelet function, suggesting a role for platelets in EPA- and DHA-mediated cardioprotection. However, it is unclear whether the cardioprotective mechanisms arise from alterations to platelet-platelet, platelet-matrix, or platelet-coagulation factor interactions. Our previous results led us to hypothesize that EPA and DHA alter the ability of platelets to catalyze the generation of thrombin. We tested this hypothesis by exogenously modifying platelet membranes with EPA and DHA, which resulted in compositional changes analogous to increased dietary EPA and DHA intake. Platelets treated with EPA and DHA showed reductions in the rate of thrombin generation and exposure of platelet phosphatidylserine. In addition, treatment of platelets with EPA and DHA decreased thrombus formation and altered the processing of thrombin precursor proteins. Furthermore, treatment of whole blood with EPA and DHA resulted in increased occlusion time and a sharply reduced accumulation of fibrin under flow conditions. These results demonstrate that EPA and DHA inhibit, but do not eliminate, the ability of platelets to catalyze thrombin generation in vitro. The ability of EPA and DHA to reduce the procoagulant function of platelets provides a possible mechanism behind the cardioprotective phenotype in individuals consuming high levels of EPA and DHA.
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Affiliation(s)
- Mark K Larson
- Department of Biology, Augustana College, Sioux Falls, SD 57197, USA.
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Haynes LM, Orfeo T, Mann KG. Rivaroxaban delivery and reversal at a venous flow rate. Arterioscler Thromb Vasc Biol 2012; 32:2877-83. [PMID: 23023369 DOI: 10.1161/atvbaha.112.300053] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
OBJECTIVE Rivaroxaban is an oral anticoagulant that directly targets both free factor Xa and factor Xa in complex with its protein cofactor, factor Va, in the prothrombinase complex. It is approved in the United States for the prophylaxis of deep vein thrombosis and stroke in patients with atrial fibrillation; however, it also carries a black box warning regarding the risk of thrombosis after discontinuation of treatment. The purpose of this study was to determine the degree to which rivaroxaban, over a range of physiologically relevant free plasma concentrations, inhibits preassembled prothrombinase at a typical venous shear rate (100 s(-1)) and to determine the dynamics of rivaroxaban washout. METHODS AND RESULTS Prothrombinase was assembled on phospholipid-coated glass capillaries. Its activity was characterized with respect to the activation of prothrombin (mean plasma concentration, 1.4 μmol/L) in the absence and presence of rivaroxaban (2, 5, and 10 nmol/L). The degree of inactivation of preassembled prothrombinase is sensitive to the solution-phase rivaroxaban concentration; however, prothrombinase unmasking upon removal of rivaroxaban is concentration independent. CONCLUSIONS The model system presented suggests that when rivaroxaban plasma concentrations decrease after cessation of therapy, there will be an unmasking of thrombus-associated prothrombinase that may be related to the reported rebound phenomena.
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Affiliation(s)
- Laura M Haynes
- Department of Biochemistry, University of Vermont College of Medicine, Colchester, VT 05446, USA
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12
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Haynes LM, Bouchard BA, Tracy PB, Mann KG. Prothrombin activation by platelet-associated prothrombinase proceeds through the prethrombin-2 pathway via a concerted mechanism. J Biol Chem 2012; 287:38647-55. [PMID: 22989889 DOI: 10.1074/jbc.m112.407791] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The protease α-thrombin is a key enzyme of the coagulation process as it is at the cross-roads of both the pro- and anti-coagulant pathways. The main source of α-thrombin in vivo is the activation of prothrombin by the prothrombinase complex assembled on either an activated cell membrane or cell fragment, the most relevant of which is the activated platelet surface. When prothrombinase is assembled on synthetic phospholipid vesicles, prothrombin activation proceeds with an initial cleavage at Arg-320 yielding the catalytically active, yet effectively anticoagulant intermediate meizothrombin, which is released from the enzyme complex ∼30-40% of the time. Prothrombinase assembled on the surface of activated platelets has been shown to proceed through the inactive intermediate prethrombin-2 via an initial cleavage at Arg-271 followed by cleavage at Arg-320. The current work tests whether or not platelet-associated prothrombinase proceeds via a concerted mechanism through a study of prothrombinase assembly and function on collagen-adhered, thrombin-activated, washed human platelets in a flow chamber. Prothrombinase assembly was demonstrated through visualization of bound factor Xa by confocal microscopy using a fluorophore-labeled anti-factor Xa antibody, which demonstrated the presence of distinct platelet subpopulations capable of binding factor Xa. When prothrombin activation was monitored at a typical venous shear rate over preassembled platelet-associated prothrombinase neither potential intermediate, meizothrombin or prethrombin-2, was observed in the effluent. Collectively, these findings suggest that platelet-associated prothrombinase activates prothrombin via an efficient concerted mechanism in which neither intermediate is released.
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Affiliation(s)
- Laura M Haynes
- Department of Biochemistry, University of Vermont College of Medicine, Burlington, Vermont 05405, USA
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Tormoen GW, Haley KM, Levine RL, McCarty OJT. Do circulating tumor cells play a role in coagulation and thrombosis? Front Oncol 2012; 2:115. [PMID: 22973557 PMCID: PMC3437466 DOI: 10.3389/fonc.2012.00115] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2012] [Accepted: 08/23/2012] [Indexed: 01/08/2023] Open
Abstract
Cancer induces a hypercoagulable state, and patients with cancer who suffer a thrombotic event have a worse prognosis than those who do not. Recurrent pathologic thrombi in patients with cancer are clinically managed with anticoagulant medications; however, anticoagulant prophylaxis is not routinely prescribed owing to a complex variety of patient and diagnosis related factors. Early identification of patients at risk for cancer-associated thrombosis would allow for personalization of anticoagulant prophylaxis and likely reduce morbidity and mortality for many cancers. The environment in which a thrombosis develops in a patient with cancer is complex and unique from patients without cancer, which creates therapeutic challenges but may also provide targets for the development of clinical assays in this context. Circulating tumor cells (CTCs) may play a role in the association between cancer and thrombosis. Cancer metastasis, the leading cause of cancer-related deaths, is facilitated by the hematogenous spread of CTCs, and CTCs accompany metastatic disease across all major types of carcinomas. The role of CTCs in the pathogenesis of thrombosis has not been studied due to the previous difficulty in identifying these rare cells, but the interaction between these circulating cells and the coagulation system is an area of study that demands attention. The development of CTC detection platforms presents a new tool by which to characterize the role for CTCs in cancer-related hypercoagulability. In addition, this area of study presents a new avenue for assessing the risk of cancer-associated thrombosis and represents a potential tool for predicting which patients may benefit from anticoagulant prophylaxis. In this review, we will discuss the evidence in support of CTC induced hypercoagulability, and highlight areas where CTC-detection platforms may provide prognostic insight into the risk of developing thrombosis for patients with cancer.
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Affiliation(s)
- Garth W. Tormoen
- Department of Biomedical Engineering, School of Medicine, Oregon Health & Science UniversityPortland, OR, USA
| | - Kristina M. Haley
- Division of Pediatric Hematology/Oncology, Department of Pediatrics, Oregon Health & Science UniversityPortland, OR, USA
| | - Ross L. Levine
- Human Oncology and Pathogenesis Program, Memorial Sloan–Kettering Cancer CenterNew York, NY, USA
| | - Owen J. T. McCarty
- Department of Biomedical Engineering, School of Medicine, Oregon Health & Science UniversityPortland, OR, USA
- Department of Cell & Developmental Biology, School of Medicine, Oregon Health & Science UniversityPortland, OR, USA
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14
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Affiliation(s)
- K G Mann
- Department of Biochemistry, University of Vermont, Colchester, VT 05446, USA.
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Flamm MH, Diamond SL. Multiscale systems biology and physics of thrombosis under flow. Ann Biomed Eng 2012; 40:2355-64. [PMID: 22460075 DOI: 10.1007/s10439-012-0557-9] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2012] [Accepted: 03/21/2012] [Indexed: 01/29/2023]
Abstract
Blood clotting under hemodynamic conditions involves numerous multiscale interactions from the molecular scale to macroscopic vessel and systemic circulation scales. Transmission of shear forces to platelet receptors such as GPIbα, P-selectin, α(2)β(1), and α(2b)β(3) controls adhesion dynamics. These forces also drive membrane tether formation, cellular deformation, and mechanosignaling in blood cells. Blood flow results in red blood cell (RBC) drift towards the center of the vessel along with a near-wall plasma layer enriched with platelets. RBC motions also dramatically enhance platelet dispersion. Trajectories of individual platelets near a thrombotic deposit dictate capture-activation-arrest dynamics as these newly arriving platelets are exposed to chemical gradients of ADP, thromboxane, and thrombin within a micron-scale boundary layer formed around the deposit. If shear forces are sufficiently elevated (>50 dyne/cm(2)), the largest polymers of von Willebrand Factor may elongate with concomitant shear-induced platelet activation. Finally, thrombin generation enhances platelet recruitment and clot strength via fibrin polymerization. By combination of coarse-graining, continuum, and stochastic algorithms, the numerical simulation of the growth rate, composition, and occlusive/embolic potential of a thrombus now spans multiscale phenomena. These simulations accommodate particular flow geometries, blood phenotype, pharmacological regimen, and reactive surfaces to help predict disease risk or response to therapy.
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Affiliation(s)
- Mathew H Flamm
- Department of Chemical and Biomolecular Engineering, Institute for Medicine and Engineering, 1024 Vagelos Research Laboratory, University of Pennsylvania, Philadelphia, PA 19104, USA
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