1
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Mitchell JL, Khan D, Rana RH, Kriek N, Unsworth AJ, Sage T, Bye AP, Laffan M, Shapiro S, Thakurta A, Grech H, Ramasamy K, Gibbins JM. Multiple myeloma and its treatment contribute to increased platelet reactivity. Platelets 2023; 34:2264940. [PMID: 37822056 DOI: 10.1080/09537104.2023.2264940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Accepted: 09/25/2023] [Indexed: 10/13/2023]
Abstract
Multiple myeloma (MM) and its precursor states, smoldering myeloma (SM) and monoclonal gammopathy of undetermined significance (MGUS) are associated with increased incidence of thrombosis, however the cause of this is unknown. Lenalidomide treatment of MM substantially improves patient survival, although significantly increases thrombotic risk by an unknown mechanism. This pilot study aimed to establish the impact of MM and its treatment with Lenalidomide on platelet function. We analyzed platelet function in MGUS, SM and MM compared to healthy controls. We report an increase in platelet reactivity in MGUS, SM, and MM where increases in fibrinogen binding, P-selectin exposure, altered receptor expression, elevated levels of aggregation and enhanced sensitivity to agonist stimulation were observed. We also demonstrate an increase in patient platelet reactivity post Lenalidomide treatment compared to pre-treatment. We show Lenalidomide treatment of platelets ex vivo increased reactivity that was associated with formation of larger thrombi at arterial shear rates but not venous shear rates. This study demonstrates a clear increase in platelet reactivity and prothrombotic potential in patients with MGUS, SM and MM which is elevated further upon treatment with Lenalidomide. Our observations suggest that more detailed studies are warranted to determine mechanisms of thrombotic complications to enable the development of new preventative strategies that specifically target platelets.
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Affiliation(s)
- Joanne L Mitchell
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, UK
- Institute for Cardiovascular Research, University of Birmingham, Birmingham, UK
| | - Dalia Khan
- Blood Theme Oxford Biomedical Research Centre, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Rekha H Rana
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, UK
| | - Neline Kriek
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, UK
| | - Amanda J Unsworth
- Department of Life Sciences, Manchester Metropolitan University, Manchester, UK
| | - Tanya Sage
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, UK
| | - Alexander P Bye
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, UK
| | - Michael Laffan
- Centre for Haematology, Department of Medicine, Imperial College London, London, UK
| | - Susan Shapiro
- Blood Theme Oxford Biomedical Research Centre, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
- Radcliffe Department of Medicine, Oxford University, Oxford, UK
| | - Anjan Thakurta
- Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences (NDORMS), University of Oxford, Oxford, UK
| | - Henri Grech
- Department of Haematology, Royal Berkshire Hospitals NHS Foundation Trust, Reading, UK
| | - Karthik Ramasamy
- Blood Theme Oxford Biomedical Research Centre, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Jonathan M Gibbins
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, UK
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2
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Geyer CE, Chen HJ, Bye AP, Manz XD, Guerra D, Caniels TG, Bijl TP, Griffith GR, Hoepel W, de Taeye SW, Veth J, Vlaar AP, Vidarsson G, Bogaard HJ, Aman J, Gibbins JM, van Gils MJ, de Winther MP, den Dunnen J. Identification of new drugs to counteract anti-spike IgG-induced hyperinflammation in severe COVID-19. Life Sci Alliance 2023; 6:e202302106. [PMID: 37699657 PMCID: PMC10497933 DOI: 10.26508/lsa.202302106] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Revised: 08/24/2023] [Accepted: 08/29/2023] [Indexed: 09/14/2023] Open
Abstract
Previously, we and others have shown that SARS-CoV-2 spike-specific IgG antibodies play a major role in disease severity in COVID-19 by triggering macrophage hyperactivation, disrupting endothelial barrier integrity, and inducing thrombus formation. This hyperinflammation is dependent on high levels of anti-spike IgG with aberrant Fc tail glycosylation, leading to Fcγ receptor hyperactivation. For development of immune-regulatory therapeutics, drug specificity is crucial to counteract excessive inflammation whereas simultaneously minimizing the inhibition of antiviral immunity. We here developed an in vitro activation assay to screen for small molecule drugs that specifically counteract antibody-induced pathology. We identified that anti-spike-induced inflammation is specifically blocked by small molecule inhibitors against SYK and PI3K. We identified SYK inhibitor entospletinib as the most promising candidate drug, which also counteracted anti-spike-induced endothelial dysfunction and thrombus formation. Moreover, entospletinib blocked inflammation by different SARS-CoV-2 variants of concern. Combined, these data identify entospletinib as a promising treatment for severe COVID-19.
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Affiliation(s)
- Chiara E Geyer
- https://ror.org/05grdyy37 Center for Experimental and Molecular Medicine, Amsterdam Institute for Infection and Immunity, Amsterdam University Medical Centers, Amsterdam, Netherlands
| | - Hung-Jen Chen
- https://ror.org/05grdyy37 Center for Experimental and Molecular Medicine, Amsterdam Institute for Infection and Immunity, Amsterdam University Medical Centers, Amsterdam, Netherlands
| | - Alexander P Bye
- Institute for Cardiovascular and Metabolic Research, and School of Biological Sciences, University of Reading, Reading, UK
- Molecular and Clinical Sciences Research Institute, St George's University, London, UK
- School of Pharmacy, University of Reading, Reading, UK
| | - Xue D Manz
- https://ror.org/05grdyy37 Pulmonary Medicine, Amsterdam University Medical Centers, Amsterdam, Netherlands
| | - Denise Guerra
- https://ror.org/05grdyy37 Medical Microbiology and Infection Prevention, Amsterdam Institute for Infection and Immunity, Amsterdam University Medical Centers, Amsterdam, Netherlands
| | - Tom G Caniels
- https://ror.org/05grdyy37 Medical Microbiology and Infection Prevention, Amsterdam Institute for Infection and Immunity, Amsterdam University Medical Centers, Amsterdam, Netherlands
| | - Tom Pl Bijl
- https://ror.org/05grdyy37 Medical Microbiology and Infection Prevention, Amsterdam Institute for Infection and Immunity, Amsterdam University Medical Centers, Amsterdam, Netherlands
| | - Guillermo R Griffith
- https://ror.org/05grdyy37 Department of Medical Biochemistry, Amsterdam Cardiovascular Sciences, Atherosclerosis & Ischemic Syndromes, Amsterdam Institute for Infection and Immunity, Inflammatory Diseases, Amsterdam University Medical Centers, Amsterdam, Netherlands
| | - Willianne Hoepel
- https://ror.org/05grdyy37 Center for Experimental and Molecular Medicine, Amsterdam Institute for Infection and Immunity, Amsterdam University Medical Centers, Amsterdam, Netherlands
| | - Steven W de Taeye
- https://ror.org/05grdyy37 Medical Microbiology and Infection Prevention, Amsterdam Institute for Infection and Immunity, Amsterdam University Medical Centers, Amsterdam, Netherlands
| | - Jennifer Veth
- https://ror.org/05grdyy37 Center for Experimental and Molecular Medicine, Amsterdam Institute for Infection and Immunity, Amsterdam University Medical Centers, Amsterdam, Netherlands
| | - Alexander Pj Vlaar
- https://ror.org/05grdyy37 Department of Intensive Care Medicine, Amsterdam Institute for Infection and Immunity, Amsterdam University Medical Centers, Amsterdam, Netherlands
| | - Gestur Vidarsson
- Experimental Immunohematology, Sanquin Research, Amsterdam, Netherlands
- Department of Biomolecular Mass Spectrometry and Proteomics, Utrecht Institute for Pharmaceutical Sciences and Bijvoet Center for Biomolecular Research, Utrecht University, Utrecht, Netherlands
| | - Harm Jan Bogaard
- https://ror.org/05grdyy37 Pulmonary Medicine, Amsterdam University Medical Centers, Amsterdam, Netherlands
| | - Jurjan Aman
- https://ror.org/05grdyy37 Pulmonary Medicine, Amsterdam University Medical Centers, Amsterdam, Netherlands
| | - Jonathan M Gibbins
- Institute for Cardiovascular and Metabolic Research, and School of Biological Sciences, University of Reading, Reading, UK
| | - Marit J van Gils
- https://ror.org/05grdyy37 Medical Microbiology and Infection Prevention, Amsterdam Institute for Infection and Immunity, Amsterdam University Medical Centers, Amsterdam, Netherlands
| | - Menno Pj de Winther
- https://ror.org/05grdyy37 Department of Medical Biochemistry, Amsterdam Cardiovascular Sciences, Atherosclerosis & Ischemic Syndromes, Amsterdam Institute for Infection and Immunity, Inflammatory Diseases, Amsterdam University Medical Centers, Amsterdam, Netherlands
| | - Jeroen den Dunnen
- https://ror.org/05grdyy37 Center for Experimental and Molecular Medicine, Amsterdam Institute for Infection and Immunity, Amsterdam University Medical Centers, Amsterdam, Netherlands
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3
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Mitchell JL, Little G, Bye AP, Gaspar RS, Unsworth AJ, Kriek N, Sage T, Stainer A, Sangowawa I, Morrow GB, Bastos RN, Shapiro S, Desborough MJ, Curry N, Gibbins JM, Whyte CS, Mutch NJ, Jones CI. Platelet factor XIII-A regulates platelet function and promotes clot retraction and stability. Res Pract Thromb Haemost 2023; 7:100200. [PMID: 37601014 PMCID: PMC10439398 DOI: 10.1016/j.rpth.2023.100200] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Revised: 05/16/2023] [Accepted: 05/23/2023] [Indexed: 08/22/2023] Open
Abstract
Background Factor XIII (FXIII) is an important proenzyme in the hemostatic system. The plasma-derived enzyme activated FXIII cross-links fibrin fibers within thrombi to increase their mechanical strength and cross-links fibrin to fibrinolytic inhibitors, specifically α2-antiplasmin, to increase resistance to fibrinolysis. We have previously shown that cellular FXIII (factor XIII-A [FXIII-A]), which is abundant in the platelet cytoplasm, is externalized onto the activated membrane and cross-links extracellular substrates. The contribution of cellular FXIII-A to platelet activation and platelet function has not been extensively studied. Objectives This study aims to identify the role of platelet FXIII-A in platelet function. Methods We used normal healthy platelets with a cell permeable FXIII inhibitor and platelets from FXIII-deficient patients as a FXIII-free platelet model in a range of platelet function and clotting tests. Results Our data demonstrate that platelet FXIII-A enhances fibrinogen binding to the platelet surface upon agonist stimulation and improves the binding of platelets to fibrinogen and aggregation under flow in a whole-blood thrombus formation assay. In the absence of FXIII-A, platelets show reduced sensitivity to agonist stimulation, including decreased P-selectin exposure and fibrinogen binding. We show that FXIII-A is involved in platelet spreading where a lack of FXIII-A reduces the ability of platelets to fully spread on fibrinogen and collagen. Our data demonstrate that platelet FXIII-A is important for clot retraction where clots formed in its absence retracted to a lesser extent. Conclusion Overall, this study shows that platelet FXIII-A functions during thrombus formation by aiding platelet activation and thrombus retraction in addition to its antifibrinolytic roles.
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Affiliation(s)
- Joanne L. Mitchell
- Institute for Cardiovascular Research, University of Birmingham, Birmingham, UK
| | - Gemma Little
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, UK
| | | | - Renato S. Gaspar
- Heart Institute, University of Sao Paulo School of Medicine, Sao Paulo, Brazil
| | - Amanda J. Unsworth
- Department of Life Sciences, Faculty of Science and Engineering, Manchester Metropolitan University, Manchester, UK
| | - Neline Kriek
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, UK
| | - Tanya Sage
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, UK
| | - Alexander Stainer
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, UK
| | - Ibidayo Sangowawa
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, UK
| | - Gael B. Morrow
- Oxford University Hospitals NHS Foundation Trust, Blood Theme Oxford Biomedical Research Centre, Oxford, UK
- Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | | | - Susan Shapiro
- Oxford University Hospitals NHS Foundation Trust, Blood Theme Oxford Biomedical Research Centre, Oxford, UK
- Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Michael J.R. Desborough
- Oxford University Hospitals NHS Foundation Trust, Blood Theme Oxford Biomedical Research Centre, Oxford, UK
| | - Nicola Curry
- Oxford University Hospitals NHS Foundation Trust, Blood Theme Oxford Biomedical Research Centre, Oxford, UK
- Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Jonathan M. Gibbins
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, UK
| | - Claire S. Whyte
- Aberdeen Cardiovascular & Diabetes Centre, School of Medicine, Medical Sciences and Nutrition, Institute of Medical Sciences, University of Aberdeen, Aberdeen, UK
| | - Nicola J. Mutch
- Aberdeen Cardiovascular & Diabetes Centre, School of Medicine, Medical Sciences and Nutrition, Institute of Medical Sciences, University of Aberdeen, Aberdeen, UK
| | - Christopher I. Jones
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, UK
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4
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Bye AP, Kriek N, Sage T, Rawlings SJ, Prodger C, Kesavan M, Lees C, Booth S, Cowen LG, Shefferd K, Desborough MJ, Gibbins JM, Eyre TA. Pirtobrutinib results in reversible platelet dysfunction compared to ibrutinib and acalabrutinib. Haematologica 2023; 108:1429-1435. [PMID: 36519322 PMCID: PMC10153540 DOI: 10.3324/haematol.2022.281402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Accepted: 12/05/2022] [Indexed: 12/23/2022] Open
Affiliation(s)
- Alexander P Bye
- Molecular and Clinical Sciences Research Institute, St George's University, Cranmer Terrace, London, United Kingdom; Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, RG6 6EX.
| | - Neline Kriek
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, RG6 6EX
| | - Tanya Sage
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, RG6 6EX
| | - Suzannah J Rawlings
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading,
| | - Catherine Prodger
- Department of Clinical Haematology, Cancer and Haematology Centre, Churchill Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, OX3 7LE
| | - Murali Kesavan
- Department of Clinical Haematology, Cancer and Haematology Centre, Churchill Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, OX3 7LE
| | - Charlotte Lees
- Department of Clinical Haematology, Cancer and Haematology Centre, Churchill Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, OX3 7LE
| | - Stephen Booth
- Department of Clinical Haematology, Royal Berkshire Hospital NHS Foundation Trust, Reading, RG1 5AN
| | - Louise G Cowen
- Haematology Late Phase Clinical Trial Unit, Oxford University Hospitals NHS Foundation Trust, Oxford, OX3 7LE
| | - Kirsty Shefferd
- Haematology Late Phase Clinical Trial Unit, Oxford University Hospitals NHS Foundation Trust, Oxford, OX3 7LE
| | - Michael J Desborough
- Department of Clinical Haematology, Oxford University Hospitals NHS Foundation Trust, Oxford, OX3 7LE
| | - Jonathan M Gibbins
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, RG6 6EX
| | - Toby A Eyre
- Department of Clinical Haematology, Cancer and Haematology Centre, Churchill Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford,
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5
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Mitchell JL, Dunster JL, Kriek N, Unsworth AJ, Sage T, Mohammed YMM, De Simone I, Taylor KA, Bye AP, Ólafsson G, Brunton M, Mark S, Dymott LD, Whyte A, Ruparelia N, Mckenna C, Gibbins JM, Jones CI. The rate of platelet activation determines thrombus size and structure at arterial shear. J Thromb Haemost 2023:S1538-7836(23)00333-1. [PMID: 37085037 DOI: 10.1016/j.jtha.2023.03.044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Revised: 03/02/2023] [Accepted: 03/28/2023] [Indexed: 04/23/2023]
Abstract
BACKGROUND The response of platelets to activating stimuli and pharmaceutical agents varies greatly within the normal population. Current platelet function tests measure endpoint levels of platelet activation without taking the speed at which platelets activate into account, potentially missing vital metrics to characterise platelet reactivity. OBJECTIVES To identify variability, to agonist and between individuals, in platelet activation kinetics and assess the impact of this on thrombus formation. METHODS We have developed a bespoke real-time flow cytometry assay and analysis package that measures the rate of platelet activation over time using two parameters of platelet activation, fibrinogen binding and P-selectin exposure. RESULTS The rate of platelet activation varied considerably within the normal population but did not correlate with maximal platelet activation, demonstrating that platelet activation rate is a separate and novel metric to describe platelet reactivity. The relative rate of platelet response between agonists was strongly correlated, suggesting a central control mechanism regulates the rate of platelet response to all agonists. CONCLUSIONS For the first time, we have shown that platelet response rate corresponds to thrombus size and structure, where faster responders form larger, more densely packed thrombi at arterial, but crucially not venous shear. We have demonstrated that the rate of platelet activation is an important metric in stratifying individual platelet responses and will provide a novel focus for the design and development of anti-platelet therapy, targeting high shear thrombosis without exacerbating bleeding at low shear.
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Affiliation(s)
- Joanne L Mitchell
- School of Biological Sciences, University of Reading, UK; Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, UK
| | | | - Neline Kriek
- School of Biological Sciences, University of Reading, UK
| | | | - Tanya Sage
- School of Biological Sciences, University of Reading, UK
| | | | | | - Kirk A Taylor
- School of Biological Sciences, University of Reading, UK
| | - Alexander P Bye
- Molecular and Clinical Sciences Research Institute, St George's University, Cranmer Terrace, London, UK
| | - Geir Ólafsson
- Bristol Composites Institute, Faculty of Civil, Aerospace and Mechanical Engineering, University of Bristol, UK
| | - Mark Brunton
- University Department of Cardiology, Royal Berkshire Hospital, UK
| | - Sharon Mark
- University Department of Cardiology, Royal Berkshire Hospital, UK
| | - Leanne D Dymott
- University Department of Cardiology, Royal Berkshire Hospital, UK
| | - Abigail Whyte
- University Department of Cardiology, Royal Berkshire Hospital, UK
| | - Neil Ruparelia
- School of Biological Sciences, University of Reading, UK; University Department of Cardiology, Royal Berkshire Hospital, UK
| | - Charlie Mckenna
- University Department of Cardiology, Royal Berkshire Hospital, UK
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6
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Gwozdz AM, Black SA, Bye AP, Gibbins JM, Patel AS, Modara B, Smith A, Saha P. O079 Predictive value for elevated platelet-derived SGPVI in venous in-stent stenosis in patients with post-thrombotic syndrome. Br J Surg 2022. [DOI: 10.1093/bjs/znac242.079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Abstract
Introduction
In-stent stenosis following intervention for post-thrombotic syndrome (PTS) occurs in ∼30% of cases, despite therapeutic anticoagulation. Our aim was to investigate whether platelets are involved.
Methods
Blood was taken from case-matched patients before and after venous stenting. Flow-cytometry was used to assess platelet activation (P-selectin and/or phosphatidylserine exposure) while= functional activity was measured by plate-based aggregation and through a flow-cell model of thrombus formation. Soluble glycoprotein VI (sGPVI) was measured in plasma. Patients with in-stent stenosis requiring reintervention (>50% diameter reduction) were compared with those who did not.
Results
Forty-five patients were recruited (median age: 43yrs (33–55yrs); 65% female), and 19/45 (42%) required reintervention (median time: 3wks (1day-3mths)). There was no difference in platelet activation or reactivity after stenting, but P-selectin exposure pre-stent was significantly higher in patients who developed in-stent stenosis (2.7%±0.4 vs 1.7%±0.2; P<0.05). Pre-stent sGPVI levels were increased in patients who developed in-stent stenosis (18.9±3.6ng/mL vs. 7.4±0.9ng/mL; P<0.01). Platelet reactivity to collagen-related peptide, a GPVI-specific platelet agonist, was reduced in patients who developed in-stent stenosis (logEC50 = -6.5M±0.3 vs -7.2M±0.2; P<0.05; n=33). Pre-stent platelet accumulation (26.6AU±0.5 vs 19.0AU±8.1; P=0.04) was significantly increased in PTS patients compared with healthy controls.
Conclusion
Venous stenting does not activate platelets, but patients who developed in-stent stenosis exhibited greater levels of pre-stent platelet activation, greater loss of platelet surface GPVI in the form of sGPVI and reduction in reactivity to GPVI activation. sGPVI may have potential to risk stratify patients undergoing venous stenting and predict who requires closer surveillance.
Take-home message
Soluble GPVI may have potential to risk-stratify patients undergoing deep venous reconstruction and predict who requires closer surveillance.
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Affiliation(s)
- AM Gwozdz
- Academic Department of Vascular Surgery, Section of Vascular Risk and Surgery, School of Cardiovascular Medicine and Science, St Thomas’ Hospital, King’s College London
| | - SA Black
- Academic Department of Vascular Surgery, Section of Vascular Risk and Surgery, School of Cardiovascular Medicine and Science, St Thomas’ Hospital, King’s College London
| | - AP Bye
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading
| | - JM Gibbins
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading
| | - AS Patel
- Academic Department of Vascular Surgery, Section of Vascular Risk and Surgery, School of Cardiovascular Medicine and Science, St Thomas’ Hospital, King’s College London
| | - B Modara
- Academic Department of Vascular Surgery, Section of Vascular Risk and Surgery, School of Cardiovascular Medicine and Science, St Thomas’ Hospital, King’s College London
| | - A Smith
- Academic Department of Vascular Surgery, Section of Vascular Risk and Surgery, School of Cardiovascular Medicine and Science, St Thomas’ Hospital, King’s College London
| | - P Saha
- Academic Department of Vascular Surgery, Section of Vascular Risk and Surgery, School of Cardiovascular Medicine and Science, St Thomas’ Hospital, King’s College London
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7
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Kriek N, Nock SH, Sage T, Khalifa B, Bye AP, Mitchell JL, Thomson S, McLaughlin MG, Jones S, Gibbins JM, Unsworth AJ. Cucurbitacins Elicit Anti-Platelet Activity via Perturbation of the Cytoskeleton and Integrin Function. Thromb Haemost 2022; 122:1115-1129. [PMID: 35253142 PMCID: PMC9385249 DOI: 10.1055/a-1788-5322] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Accepted: 11/06/2021] [Indexed: 11/23/2022]
Abstract
Cucurbitacins are dietary compounds that have been shown to elicit a range of anti-tumour, anti-inflammatory and anti-atherosclerotic activities. Originally identified as signal transducer and activator of transcription, STAT, inhibitors, a variety of mechanisms of action have since been described, including dysregulation of the actin cytoskeleton and disruption of integrin function. Integrin outside-in signalling and cytoskeletal rearrangements are critical for the propagation of stable thrombus formation and clot retraction following platelet adhesion at the site of vessel damage. The effects of cucurbitacins on platelet function and thrombus formation are unknown. We report for the first time anti-platelet and anti-thrombotic effects of cucurbitacins B, E and I in human platelets. Treatment of platelets with cucurbitacins resulted in attenuation of platelet aggregation, secretion and fibrinogen binding following stimulation by platelet agonists. Cucurbitacins were also found to potently inhibit other integrin- and cytoskeleton-mediated events, including adhesion, spreading and clot retraction. Further investigation of cytoskeletal dynamics found treatment with cucurbitacins altered cofilin phosphorylation, enhanced activation and increased F actin polymerisation and microtubule assembly. Disruption to cytoskeletal dynamics has been previously shown to impair integrin activation, platelet spreading and clot retraction. Anti-platelet properties of cucurbitacins were found to extend to a disruption of stable thrombus formation, with an increase in thrombi instability and de-aggregation under flow. Our research identifies novel, anti-platelet and anti-thrombotic actions of cucurbitacins that appear to be linked to dysregulation of cytoskeletal dynamics and integrin function.
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Affiliation(s)
- Neline Kriek
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, United Kingdom
| | - Sophie H. Nock
- Department of Life Sciences, Faculty of Science and Engineering, Manchester Metropolitan University, Manchester, United Kingdom
| | - Tanya Sage
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, United Kingdom
| | - Badrija Khalifa
- Department of Life Sciences, Faculty of Science and Engineering, Manchester Metropolitan University, Manchester, United Kingdom
| | - Alexander P. Bye
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, United Kingdom
| | - Joanne L. Mitchell
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, United Kingdom
| | - Steven Thomson
- Department of Life Sciences, Faculty of Science and Engineering, Manchester Metropolitan University, Manchester, United Kingdom
| | - Mark G. McLaughlin
- Department of Chemistry, Lancaster University, Lancaster, United Kingdom
| | - Sarah Jones
- Department of Life Sciences, Faculty of Science and Engineering, Manchester Metropolitan University, Manchester, United Kingdom
| | - Jonathan M. Gibbins
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, United Kingdom
| | - Amanda J. Unsworth
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, United Kingdom
- Department of Life Sciences, Faculty of Science and Engineering, Manchester Metropolitan University, Manchester, United Kingdom
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8
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Alatawi KA, Ravishankar D, Patra PH, Bye AP, Stainer AR, Patel K, Widera D, Vaiyapuri S. 1,8-Cineole Affects Agonists-Induced Platelet Activation, Thrombus Formation and Haemostasis. Cells 2021; 10:2616. [PMID: 34685597 PMCID: PMC8533741 DOI: 10.3390/cells10102616] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Revised: 09/27/2021] [Accepted: 09/30/2021] [Indexed: 02/06/2023] Open
Abstract
1,8-cineole, a monoterpenoid is a major component of eucalyptus oil and has been proven to possess numerous beneficial effects in humans. Notably, 1,8-cineole is the primary active ingredient of a clinically approved drug, Soledum® which is being mainly used for the maintenance of sinus and respiratory health. Due to its clinically valuable properties, 1,8-cineole has gained significant scientific interest over the recent years specifically to investigate its anti-inflammatory and antioxidant effects. However, the impact of 1,8-cineole on the modulation of platelet activation, thrombosis and haemostasis was not fully established. Therefore, in this study, we demonstrate the effects of 1,8-cineole on agonists-induced platelet activation, thrombus formation under arterial flow conditions and haemostasis in mice. 1,8-cineole largely inhibits platelet activation stimulated by glycoprotein VI (GPVI) agonists such as collagen and cross-linked collagen-related peptide (CRP-XL), while it displays minimal inhibitory effects on thrombin or ADP-induced platelet aggregation. It inhibited inside-out signalling to integrin αIIbβ3 and outside-in signalling triggered by the same integrin as well as granule secretion and intracellular calcium mobilisation in platelets. 1,8-cineole affected thrombus formation on collagen-coated surface under arterial flow conditions and displayed a minimal effect on haemostasis of mice at a lower concentration of 6.25 µM. Notably, 1,8-cineole was found to be non-toxic to platelets up to 50 µM concentration. The investigation on the molecular mechanisms through which 1,8-cineole inhibits platelet function suggests that this compound affects signalling mediated by various molecules such as AKT, Syk, LAT, and cAMP in platelets. Based on these results, we conclude that 1,8-cineole may act as a potential therapeutic agent to control unwarranted platelet reactivity under various pathophysiological settings.
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Affiliation(s)
- Kahdr A. Alatawi
- School of Pharmacy, University of Reading, Reading RG6 6UB, UK; (K.A.A.); (D.R.); (P.H.P.); (D.W.)
| | - Divyashree Ravishankar
- School of Pharmacy, University of Reading, Reading RG6 6UB, UK; (K.A.A.); (D.R.); (P.H.P.); (D.W.)
| | - Pabitra H. Patra
- School of Pharmacy, University of Reading, Reading RG6 6UB, UK; (K.A.A.); (D.R.); (P.H.P.); (D.W.)
| | - Alexander P. Bye
- School of Biological Sciences, University of Reading, Reading RG6 6UB, UK; (A.P.B.); (A.R.S.); (K.P.)
| | - Alexander R. Stainer
- School of Biological Sciences, University of Reading, Reading RG6 6UB, UK; (A.P.B.); (A.R.S.); (K.P.)
| | - Ketan Patel
- School of Biological Sciences, University of Reading, Reading RG6 6UB, UK; (A.P.B.); (A.R.S.); (K.P.)
| | - Darius Widera
- School of Pharmacy, University of Reading, Reading RG6 6UB, UK; (K.A.A.); (D.R.); (P.H.P.); (D.W.)
| | - Sakthivel Vaiyapuri
- School of Pharmacy, University of Reading, Reading RG6 6UB, UK; (K.A.A.); (D.R.); (P.H.P.); (D.W.)
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9
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Unsworth AJ, Bye AP, Sage T, Gaspar RS, Eaton N, Drew C, Stainer A, Kriek N, Volberding PJ, Hutchinson JL, Riley R, Jones S, Mundell SJ, Cui W, Falet H, Gibbins JM. Antiplatelet properties of Pim kinase inhibition are mediated through disruption of thromboxane A2 receptor signaling. Haematologica 2021; 106:1968-1978. [PMID: 32467143 PMCID: PMC8252961 DOI: 10.3324/haematol.2019.223529] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Indexed: 12/17/2022] Open
Abstract
Pim kinases are upregulated in several forms of cancer, contributing to cell survival and tumor development, but their role in platelet function and thrombotic disease has not been explored. We report for the first time that Pim-1 kinase is expressed in human and mouse platelets. Genetic deletion or pharmacological inhibition of Pim kinase results in reduced thrombus formation but is not associated with impaired hemostasis. Attenuation of thrombus formation was found to be due to inhibition of the thromboxane A2 receptor as effects on platelet function were non-additive to inhibition caused by the cyclo-oxygenase inhibitor indomethacin or the thromboxane A2 receptor antagonist GR32191. Treatment with Pim kinase inhibitors caused reduced surface expression of the thromboxane A2 receptor and resulted in reduced responses to thromboxane A2 receptor agonists, indicating a role for Pim kinase in the regulation of thromboxane A2 receptor function. Our research identifies a novel, Pim kinase-dependent regulatory mechanism for the thromboxane A2 receptor and represents a new targeting strategy that is independent of cyclo-oxygenase-1 inhibition or direct antagonism of the thromboxane A2 receptor that, while attenuating thrombosis, does not increase bleeding.
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Affiliation(s)
- Amanda J Unsworth
- University of Reading and Dept. of Life Sciences, Manchester Metropolitan University Manchester, UK
| | - Alexander P Bye
- Institute for Cardiovascular, Metabolic Research, University of Reading, Reading, UK
| | - Tanya Sage
- Institute for Cardiovascular and Metabolic Research, University of Reading, Reading, UK
| | - Renato S Gaspar
- Institute for Cardiovascular and Metabolic Research, University of Reading, Reading, UK
| | - Nathan Eaton
- Blood Research Institute and Medical College of Wisconsin, Versiti, Milwaukee, WI, USA
| | - Caleb Drew
- Blood Research Institute, Versiti, Milwaukee, WI, USA
| | - Alexander Stainer
- Institute for Cardiovascular and Metabolic Research, University of Reading, Reading, UK
| | - Neline Kriek
- Institute for Cardiovascular and Metabolic Research, University of Reading, Reading, UK
| | - Peter J Volberding
- Blood Research Institute and Medical College of Wisconsin, Versiti, Milwaukee, WI, USA
| | - James L Hutchinson
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| | - Ryan Riley
- Department of Life Sciences, Manchester Metropolitan University, Manchester, UK
| | - Sarah Jones
- Department of Life Sciences, Manchester Metropolitan University, Manchester, UK
| | - Stuart J Mundell
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| | - Weiguo Cui
- Blood Research Institute, Versiti and Medical College of Wisconsin, Milwaukee, WI, USA
| | - Hervé Falet
- Blood Research Institute, Versiti and Medical College of Wisconsin, Milwaukee, WI, USA
| | - Jonathan M Gibbins
- Institute for Cardiovascular and Metabolic Research, University of Reading, Reading, UK
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10
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Dunster JL, Unsworth AJ, Bye AP, Haining EJ, Sowa MA, Di Y, Sage T, Pallini C, Pike JA, Hardy AT, Nieswandt B, García Á, Watson SP, Poulter NS, Gibbins JM, Pollitt AY. Interspecies differences in protein expression do not impact the spatiotemporal regulation of glycoprotein VI mediated activation. J Thromb Haemost 2020; 18:485-496. [PMID: 31680418 PMCID: PMC7027541 DOI: 10.1111/jth.14673] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Revised: 10/29/2019] [Accepted: 10/30/2019] [Indexed: 12/13/2022]
Abstract
BACKGROUND Accurate protein quantification is a vital prerequisite for generating meaningful predictions when using systems biology approaches, a method that is increasingly being used to unravel the complexities of subcellular interactions and as part of the drug discovery process. Quantitative proteomics, flow cytometry, and western blotting have been extensively used to define human platelet protein copy numbers, yet for mouse platelets, a model widely used for platelet research, evidence is largely limited to a single proteomic dataset in which the total amount of proteins was generally comparatively higher than those found in human platelets. OBJECTIVES To investigate the functional implications of discrepancies between levels of mouse and human proteins in the glycoprotein VI (GPVI) signalling pathway using a systems pharmacology model of GPVI. METHODS The protein copy number of mouse platelet receptors was determined using flow cytometry. The Virtual Platelet, a mathematical model of GPVI signalling, was used to determine the consequences of protein copy number differences observed between human and mouse platelets. RESULTS AND CONCLUSION Despite the small size of mouse platelets compared to human platelets they possessed a greater density of surface receptors alongside a higher concentration of intracellular signalling proteins. Surprisingly the predicted temporal profile of Syk activity was similar in both species with predictions supported experimentally. Super resolution microscopy demonstrates that the spatial distribution of Syk is similar between species, suggesting that the spatial distribution of receptors and signalling molecules in activated platelets, rather than their copy number, is important for signalling pathway regulation.
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Affiliation(s)
- Joanne L. Dunster
- Institute for Cardiovascular and Metabolic Research (ICMR)School of Biological SciencesUniversity of ReadingReadingUK
| | - Amanda J. Unsworth
- Institute for Cardiovascular and Metabolic Research (ICMR)School of Biological SciencesUniversity of ReadingReadingUK
- Department of Life SciencesSchool of Science and EngineeringManchester Metropolitan UniversityManchesterUK
| | - Alexander P. Bye
- Institute for Cardiovascular and Metabolic Research (ICMR)School of Biological SciencesUniversity of ReadingReadingUK
| | - Elizabeth J. Haining
- Institute of Cardiovascular Sciences (ICVS)College of Medical and Dental SciencesUniversity of BirminghamBirminghamUK
| | - Marcin A. Sowa
- Institute for Cardiovascular and Metabolic Research (ICMR)School of Biological SciencesUniversity of ReadingReadingUK
- Platelet Proteomics GroupCenter for Research in Molecular Medicine and Chronic Diseases (CIMUS)Universidade de Santiago de CompostelaSantiago de CompostelaSpain
| | - Ying Di
- Institute of Cardiovascular Sciences (ICVS)College of Medical and Dental SciencesUniversity of BirminghamBirminghamUK
| | - Tanya Sage
- Institute for Cardiovascular and Metabolic Research (ICMR)School of Biological SciencesUniversity of ReadingReadingUK
| | - Chiara Pallini
- Institute of Cardiovascular Sciences (ICVS)College of Medical and Dental SciencesUniversity of BirminghamBirminghamUK
| | - Jeremy A. Pike
- Centre of Membrane Proteins and Receptors (COMPARE)Universities of Birmingham and NottinghamMidlandsBirminghamUK
| | - Alexander T. Hardy
- Institute of Cardiovascular Sciences (ICVS)College of Medical and Dental SciencesUniversity of BirminghamBirminghamUK
| | - Bernhard Nieswandt
- Department of Experimental BiomedicineUniversity HospitalUniversity of WürzburgWürzburgGermany
| | - Ángel García
- Platelet Proteomics GroupCenter for Research in Molecular Medicine and Chronic Diseases (CIMUS)Universidade de Santiago de CompostelaSantiago de CompostelaSpain
| | - Steve P. Watson
- Institute of Cardiovascular Sciences (ICVS)College of Medical and Dental SciencesUniversity of BirminghamBirminghamUK
- Centre of Membrane Proteins and Receptors (COMPARE)Universities of Birmingham and NottinghamMidlandsBirminghamUK
| | - Natalie S. Poulter
- Institute of Cardiovascular Sciences (ICVS)College of Medical and Dental SciencesUniversity of BirminghamBirminghamUK
- Centre of Membrane Proteins and Receptors (COMPARE)Universities of Birmingham and NottinghamMidlandsBirminghamUK
| | - Jonathan M. Gibbins
- Institute for Cardiovascular and Metabolic Research (ICMR)School of Biological SciencesUniversity of ReadingReadingUK
| | - Alice Y. Pollitt
- Institute for Cardiovascular and Metabolic Research (ICMR)School of Biological SciencesUniversity of ReadingReadingUK
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11
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Bye AP, Gibbins JM, Mahaut-Smith MP. Ca 2+ waves coordinate purinergic receptor-evoked integrin activation and polarization. Sci Signal 2020; 13:13/615/eaav7354. [PMID: 31964805 DOI: 10.1126/scisignal.aav7354] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Cells sense extracellular nucleotides through the P2Y class of purinergic G protein-coupled receptors (GPCRs), which stimulate integrin activation through signaling events, including intracellular Ca2+ mobilization. We investigated the relationship between P2Y-stimulated repetitive Ca2+ waves and fibrinogen binding to the platelet integrin αIIbβ3 (GPIIb/IIIa) through confocal fluorescence imaging of primary rat megakaryocytes. Costimulation of the receptors P2Y1 and P2Y12 generated a series of Ca2+ transients that each induced a rapid, discrete increase in fibrinogen binding. The peak and net increase of individual fibrinogen binding events correlated with the Ca2+ transient amplitude and frequency, respectively. Using BAPTA loading and selective receptor antagonists, we found that Ca2+ mobilization downstream of P2Y1 was essential for ADP-evoked fibrinogen binding, whereas P2Y12 and the kinase PI3K were also required for αIIbβ3 activation and enhanced the number of Ca2+ transients. ADP-evoked fibrinogen binding was initially uniform over the cell periphery but subsequently redistributed with a polarity that correlated with the direction of the Ca2+ waves. Polarization of αIIbβ3 may be mediated by the actin cytoskeleton, because surface-bound fibrinogen is highly immobile, and its motility was enhanced by cytoskeletal disruption. In conclusion, spatial and temporal patterns of Ca2+ increase enable fine control of αIIbβ3 activation after cellular stimulation. P2Y1-stimulated Ca2+ transients coupled to αIIbβ3 activation only in the context of P2Y12 coactivation, thereby providing an additional temporal mechanism of synergy between these Gq- and Gi-coupled GPCRs.
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Affiliation(s)
- Alexander P Bye
- Institute for Cardiovascular and Metabolic Research, University of Reading, Reading RG6 6AS, UK.
| | - Jonathan M Gibbins
- Institute for Cardiovascular and Metabolic Research, University of Reading, Reading RG6 6AS, UK
| | - Martyn P Mahaut-Smith
- Department of Molecular and Cell Biology, University of Leicester, Leicester LE1 7RH, UK.
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12
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Stainer AR, Sasikumar P, Bye AP, Unsworth AJ, Holbrook LM, Tindall M, Lovegrove JA, Gibbins JM. The Metabolites of the Dietary Flavonoid Quercetin Possess Potent Antithrombotic Activity, and Interact with Aspirin to Enhance Antiplatelet Effects. TH Open 2019; 3:e244-e258. [PMID: 31367693 PMCID: PMC6667742 DOI: 10.1055/s-0039-1694028] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Accepted: 06/24/2019] [Indexed: 01/09/2023] Open
Abstract
Quercetin, a dietary flavonoid, has been reported to possess antiplatelet activity. However, its extensive metabolism following ingestion has resulted in difficulty elucidating precise mechanisms of action. In this study, we aimed to characterize the antiplatelet mechanisms of two methylated metabolites of quercetin-isorhamnetin and tamarixetin-and explore potential interactions with aspirin. Isorhamnetin and tamarixetin inhibited human platelet aggregation, and suppressed activatory processes including granule secretion, integrin αIIbβ3 function, calcium mobilization, and spleen tyrosine kinase (Syk)/linker for activation of T cells (LAT) phosphorylation downstream of glycoprotein VI with similar potency to quercetin. All three flavonoids attenuated thrombus formation in an in vitro microfluidic model, and isoquercetin, a 3-O-glucoside of quercetin, inhibited thrombosis in a murine laser injury model. Isorhamnetin, tamarixetin, and quercetin enhanced the antiplatelet effects of aspirin more-than-additively in a plate-based aggregometry assay, reducing aspirin IC 50 values by an order of magnitude, with this synergy maintained in a whole blood test of platelet function. Our data provide mechanistic evidence for the antiplatelet activity of two quercetin metabolites, isorhamnetin and tamarixetin, and suggest a potential antithrombotic role for these flavonoids. In combination with their interactions with aspirin, this may represent a novel avenue of investigation for the development of new antithrombotic strategies and management of current therapies.
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Affiliation(s)
- Alexander R Stainer
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, United Kingdom
| | - Parvathy Sasikumar
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, United Kingdom.,Centre for Haematology, Imperial College London, London, United Kingdom
| | - Alexander P Bye
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, United Kingdom
| | - Amanda J Unsworth
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, United Kingdom.,School of Healthcare Science, Manchester Metropolitan University, Manchester, United Kingdom
| | - Lisa M Holbrook
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, United Kingdom.,School of Cardiovascular Medicine and Sciences, King's College London, London, United Kingdom
| | - Marcus Tindall
- Department of Mathematics and Statistics, University of Reading, Reading, United Kingdom
| | - Julie A Lovegrove
- Department of Food and Nutritional Sciences, Hugh Sinclair Unit of Human Nutrition, University of Reading, Reading, United Kingdom
| | - Jonathan M Gibbins
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, United Kingdom
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13
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Abstract
The MEK inhibitors cobimetinib and trametinib are used in combination with BRAF inhibitors to treat metastatic melanoma but increase rates of hemorrhage relative to BRAF inhibitors alone. Platelets express several members of the MAPK signalling cascade including MEK1 and MEK2 and ERK1 and ERK2 but their role in platelet function and haemostasis is ambiguous as previous reports have been contradictory. It is therefore unclear if MEK inhibitors might be causing platelet dysfunction and contributing to increased hemorrhage. In the present study we performed pharmacological characterisation of cobimetinib and trametinib in vitro to investigate potential for MEK inhibitors to cause platelet dysfunction. We report that whilst both cobimetinib and trametinib are potent inhibitors of platelet MEK activity, treatment with trametinib did not alter platelet function. Treatment with cobimetinib results in inhibition of platelet aggregation, integrin activation, alpha-granule secretion and adhesion but only at suprapharmacological concentrations. We identified that the inhibitory effects of high concentrations of cobimetinib are associated with off-target inhibition on Akt and PKC. Neither inhibitor caused any alteration in thrombus formation on collagen under flow conditions in vitro. Our findings demonstrate that platelets are able to function normally when MEK activity is fully inhibited, indicating MEK activity is dispensable for normal platelet function. We conclude that the MEK inhibitors cobimetinib and trametinib do not induce platelet dysfunction and are therefore unlikely to contribute to increased incidence of bleeding reported during MEK inhibitor therapy.
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Affiliation(s)
- Amanda J Unsworth
- a Institute for Cardiovascular and Metabolic Research , University of Reading, School of Biological Sciences , Reading , UK
| | - Alexander P Bye
- a Institute for Cardiovascular and Metabolic Research , University of Reading, School of Biological Sciences , Reading , UK
| | - Neline Kriek
- a Institute for Cardiovascular and Metabolic Research , University of Reading, School of Biological Sciences , Reading , UK
| | - Tanya Sage
- a Institute for Cardiovascular and Metabolic Research , University of Reading, School of Biological Sciences , Reading , UK
| | - Ashley A Osborne
- a Institute for Cardiovascular and Metabolic Research , University of Reading, School of Biological Sciences , Reading , UK
| | - Dillon Donaghy
- b Department of Microbiology Immunology and Pathology , Colorado State University , Fort Collins , CO , USA
| | - Jonathan M Gibbins
- a Institute for Cardiovascular and Metabolic Research , University of Reading, School of Biological Sciences , Reading , UK
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14
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Abstract
Existing methods for measuring the response of individual platelets to stimulation are limited. They either measure each platelet at one discrete time-point (flow cytometry) or rely on adhesive ligands to immobilize platelets that concomitantly generate activation signals (microscopy). Such methods of immobilization make it impossible to assess resting platelets, the changes that occur as platelets transition from resting to active states, or the signals generated by soluble agonists, such as ADP and thrombin, or by mechanical stimulus, independently from those generated by the adhesive ligand. Here we describe a microscopy method that allows the immobilization of platelets to a glass cover slip without triggering platelet activation. This method makes use of specific antibodies that bind platelet PECAM-1 without activating it. Platelets can therefore be immobilized to PECAM-1 antibody coated biochips without causing activation and perfused with agonists or inhibitors. Using this method, platelets can be stimulated by an array of soluble agonists at any concentration or combination, in the presence or absence of inhibitors or shear forces. This chapter describes in detail this PECAM-1 mediated immobilized platelet method and its use for measuring changes in Ca2+ signaling in individual platelets under a number of different conditions. While we focus on the measurement of Ca2+ dynamics in this chapter, it is important to consider that the basic method we describe will easily lend its self to other measures of platelet activation (integrin activation, shape change, actin dynamics, degranulation), and may, therefore, be used to measure almost any facet of platelet activation.
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Affiliation(s)
- Alexander P Bye
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, UK
| | - Zeki Ilkan
- Department of Molecular and Cell Biology, University of Leicester, Leicester, UK
| | - Amanda J Unsworth
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, UK
| | - Chris I Jones
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, UK.
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15
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Bye AP, Gibbins JM. Move along, nothing to see here: Btk inhibitors stop platelets sticking to plaques. J Thromb Haemost 2018; 16:1461-1463. [PMID: 30030898 DOI: 10.1111/jth.14201] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Indexed: 01/24/2023]
Affiliation(s)
- A P Bye
- Institute for Cardiovascular and Metabolic Research, University of Reading, Reading, UK
| | - J M Gibbins
- Institute for Cardiovascular and Metabolic Research, University of Reading, Reading, UK
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16
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Abstract
High-throughput assays are important biological research tools but are rarely utilized for platelet research. However, screening compounds for efficacy against a physiologically relevant cellular response in primary cells such as platelets can be an advantageous approach to compound screening and drug development. In this section we describe a panel of three high-throughput microtiter plate assays designed for platelets that can be used as the basis for compound screening, or be modified and used individually to increase throughput in platelet research laboratories. The platelet adhesion assay has the lowest requirement for platelet numbers and is therefore capable of the greatest throughput and so is suggested as the primary screen used to identify hits. A secondary screen against the "gold standard" of platelet function, aggregation, is used to confirm and further characterize hits. Finally, a Ca2+ assay is used for initial mechanistic characterization to begin the process of elucidating the mode of action of hit compounds.
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Affiliation(s)
- Alexander P Bye
- Institute for Metabolic and Cardiovascular Research, School of Biological Sciences, University of Reading, Reading, UK.
| | - Amanda J Unsworth
- Institute for Metabolic and Cardiovascular Research, School of Biological Sciences, University of Reading, Reading, UK
| | - Jonathan M Gibbins
- Institute for Metabolic and Cardiovascular Research, School of Biological Sciences, University of Reading, Reading, UK
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17
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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18
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Unsworth AJ, Flora GD, Sasikumar P, Bye AP, Sage T, Kriek N, Crescente M, Gibbins JM. RXR Ligands Negatively Regulate Thrombosis and Hemostasis. Arterioscler Thromb Vasc Biol 2017; 37:812-822. [PMID: 28254816 PMCID: PMC5405776 DOI: 10.1161/atvbaha.117.309207] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Accepted: 02/13/2017] [Indexed: 12/17/2022]
Abstract
Supplemental Digital Content is available in the text. Objective— Platelets have been found to express intracellular nuclear receptors including the retinoid X receptors (RXRα and RXRβ). Treatment of platelets with ligands of RXR has been shown to inhibit platelet responses to ADP and thromboxane A2; however, the effects on responses to other platelet agonists and the underlying mechanism have not been fully characterized. Approach and Results— The effect of 9-cis-retinoic acid, docosahexaenoic acid and methoprene acid on collagen receptor (glycoprotein VI [GPVI]) agonists and thrombin-stimulated platelet function; including aggregation, granule secretion, integrin activation, calcium mobilization, integrin αIIbβ3 outside-in signaling and thrombus formation in vitro and in vivo were determined. Treatment of platelets with RXR ligands resulted in attenuation of platelet functional responses after stimulation by GPVI agonists or thrombin and inhibition of integrin αIIbβ3 outside-in signaling. Treatment with 9-cis-retinoic acid caused inhibition of thrombus formation in vitro and an impairment of thrombosis and hemostasis in vivo. Both RXR ligands stimulated protein kinase A activation, measured by VASP S157 phosphorylation, that was found to be dependent on both cAMP and nuclear factor κ-light-chain-enhancer of activated B cell activity. Conclusions— This study identifies a widespread, negative regulatory role for RXR in the regulation of platelet functional responses and thrombus formation and describes novel events that lead to the upregulation of protein kinase A, a known negative regulator of many aspects of platelet function. This mechanism may offer a possible explanation for the cardioprotective effects described in vivo after treatment with RXR ligands.
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Affiliation(s)
- Amanda J Unsworth
- From the Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, United Kingdom
| | - Gagan D Flora
- From the Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, United Kingdom
| | - Parvathy Sasikumar
- From the Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, United Kingdom
| | - Alexander P Bye
- From the Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, United Kingdom
| | - Tanya Sage
- From the Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, United Kingdom
| | - Neline Kriek
- From the Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, United Kingdom
| | - Marilena Crescente
- From the Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, United Kingdom
| | - Jonathan M Gibbins
- From the Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, United Kingdom.
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19
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Bye AP, Unsworth AJ, Gibbins JM. Platelet signaling: a complex interplay between inhibitory and activatory networks. J Thromb Haemost 2016; 14:918-30. [PMID: 26929147 PMCID: PMC4879507 DOI: 10.1111/jth.13302] [Citation(s) in RCA: 99] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Accepted: 02/11/2016] [Indexed: 01/22/2023]
Abstract
The role of platelets in hemostasis and thrombosis is dependent on a complex balance of activatory and inhibitory signaling pathways. Inhibitory signals released from the healthy vasculature suppress platelet activation in the absence of platelet receptor agonists. Activatory signals present at a site of injury initiate platelet activation and thrombus formation; subsequently, endogenous negative signaling regulators dampen activatory signals to control thrombus growth. Understanding the complex interplay between activatory and inhibitory signaling networks is an emerging challenge in the study of platelet biology, and necessitates a systematic approach to utilize experimental data effectively. In this review, we will explore the key points of platelet regulation and signaling that maintain platelets in a resting state, mediate activation to elicit thrombus formation, or provide negative feedback. Platelet signaling will be described in terms of key signaling molecules that are common to the pathways activated by platelet agonists and can be described as regulatory nodes for both positive and negative regulators.
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Affiliation(s)
- A P Bye
- Institute of Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, UK
| | - A J Unsworth
- Institute of Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, UK
| | - J M Gibbins
- Institute of Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, UK
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20
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Bye AP, Unsworth AJ, Vaiyapuri S, Stainer AR, Fry MJ, Gibbins JM. Ibrutinib Inhibits Platelet Integrin αIIbβ3 Outside-In Signaling and Thrombus Stability But Not Adhesion to Collagen. Arterioscler Thromb Vasc Biol 2015; 35:2326-35. [PMID: 26359510 DOI: 10.1161/atvbaha.115.306130] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 08/28/2015] [Indexed: 01/16/2023]
Abstract
OBJECTIVE Ibrutinib is an irreversible Bruton tyrosine kinase inhibitor approved for treatment of Waldenstrom macroglobulinemia, chronic lymphocytic leukemia, and mantle cell lymphoma that increases the risk of bleeding among patients. Platelets from ibrutinib-treated patients exhibit deficiencies in collagen-evoked signaling in suspension; however, the significance of this observation and how it relates to bleeding risk is unclear, as platelets encounter immobile collagen in vivo. We sought to clarify the effects of ibrutinib on platelet function to better understand the mechanism underlying bleeding risk. APPROACH AND RESULTS By comparing signaling in suspension and during adhesion to immobilized ligands, we found that the collagen signaling deficiency caused by ibrutinib is milder during adhesion to immobilized collagen. We also found that platelets in whole blood treated with ibrutinib adhered to collagen under arterial shear but formed unstable thrombi, suggesting that the collagen signaling deficiency caused by ibrutinib may not be the predominant cause of bleeding in vivo. However, clot retraction and signaling evoked by platelet adhesion to immobilized fibrinogen were also inhibited by ibrutinib, indicating that integrin αIIbβ3 outside-in signaling is also effected in addition to GPVI signaling. When ibrutinib was combined with the P2Y12 inhibitor, cangrelor, thrombus formation under arterial shear was inhibited additively. CONCLUSIONS These findings suggest that (1) ibrutinib causes GPVI and integrin αIIbβ3 platelet signaling deficiencies that result in formation of unstable thrombi and may contribute toward bleeding observed in vivo and (2) combining ibrutinib with P2Y12 antagonists, which also inhibit thrombus stability, may have a detrimental effect on hemostasis.
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Affiliation(s)
- Alexander P Bye
- From the Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, United Kingdom
| | - Amanda J Unsworth
- From the Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, United Kingdom
| | - Sakthivel Vaiyapuri
- From the Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, United Kingdom
| | - Alexander R Stainer
- From the Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, United Kingdom
| | - Michael J Fry
- From the Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, United Kingdom
| | - Jonathan M Gibbins
- From the Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, United Kingdom.
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21
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Vaiyapuri S, Jones CI, Sasikumar P, Moraes LA, Munger SJ, Wright JR, Ali MS, Sage T, Kaiser WJ, Tucker KL, Stain CJ, Bye AP, Jones S, Oviedo-Orta E, Simon AM, Mahaut-Smith MP, Gibbins JM. Gap junctions and connexin hemichannels underpin hemostasis and thrombosis. Circulation 2012; 125:2479-91. [PMID: 22528526 PMCID: PMC3378664 DOI: 10.1161/circulationaha.112.101246] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Connexins are a widespread family of membrane proteins that assemble into hexameric hemichannels, also known as connexons. Connexons regulate membrane permeability in individual cells or couple between adjacent cells to form gap junctions and thereby provide a pathway for regulated intercellular communication. We have examined the role of connexins in platelets, blood cells that circulate in isolation but on tissue injury adhere to each other and the vessel wall to prevent blood loss and to facilitate wound repair. METHODS AND RESULTS We report the presence of connexins in platelets, notably connexin37, and that the formation of gap junctions within platelet thrombi is required for the control of clot retraction. Inhibition of connexin function modulated a range of platelet functional responses before platelet-platelet contact and reduced laser-induced thrombosis in vivo in mice. Deletion of the Cx37 gene (Gja4) in transgenic mice reduced platelet aggregation, fibrinogen binding, granule secretion, and clot retraction, indicating an important role for connexin37 hemichannels and gap junctions in platelet thrombus function. CONCLUSIONS Together, these data demonstrate that platelet gap junctions and hemichannels underpin the control of hemostasis and thrombosis and represent potential therapeutic targets.
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Affiliation(s)
- Sakthivel Vaiyapuri
- Institute for Cardiovascular & Metabolic Research, School of Biological Sciences, University of Reading, Reading, United Kingdom
| | - Chris I. Jones
- Institute for Cardiovascular & Metabolic Research, School of Biological Sciences, University of Reading, Reading, United Kingdom
| | - Parvathy Sasikumar
- Institute for Cardiovascular & Metabolic Research, School of Biological Sciences, University of Reading, Reading, United Kingdom
| | - Leonardo A. Moraes
- Institute for Cardiovascular & Metabolic Research, School of Biological Sciences, University of Reading, Reading, United Kingdom
| | | | - Joy R. Wright
- Dept of Cell Physiology & Pharmacology, University of Leicester, Leicester
| | - Marfoua S. Ali
- Institute for Cardiovascular & Metabolic Research, School of Biological Sciences, University of Reading, Reading, United Kingdom
| | - Tanya Sage
- Institute for Cardiovascular & Metabolic Research, School of Biological Sciences, University of Reading, Reading, United Kingdom
| | - William J. Kaiser
- Institute for Cardiovascular & Metabolic Research, School of Biological Sciences, University of Reading, Reading, United Kingdom
| | - Katherine L. Tucker
- Institute for Cardiovascular & Metabolic Research, School of Biological Sciences, University of Reading, Reading, United Kingdom
| | | | - Alexander P. Bye
- Dept of Cell Physiology & Pharmacology, University of Leicester, Leicester
| | - Sarah Jones
- Dept of Cell Physiology & Pharmacology, University of Leicester, Leicester
| | - Ernesto Oviedo-Orta
- Cardiovascular Biology Research, Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
| | | | | | - Jonathan M. Gibbins
- Institute for Cardiovascular & Metabolic Research, School of Biological Sciences, University of Reading, Reading, United Kingdom
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22
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Moore HD, Smith CA, Hartman TD, Bye AP. Visualization and characterization of the acrosome reaction of human spermatozoa by immunolocalization with monoclonal antibody. Gamete Res 1987; 17:245-9. [PMID: 3333757 DOI: 10.1002/mrd.1120170308] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
A monoclonal antibody generated against hamster epididymal spermatozoa and recognizing an antigen within the acrosome was used in conjunction with FITC-antimouse immunoglobulin as a marker of the human acrosome during sperm development, capacitation, and the acrosome reaction. The specificity of binding of the monoclonal antibody was assessed using immunolocalization by epi-fluorescence and electron microscopy. Immunofluorescence revealed that antibody bound over the entire anterior acrosome in hamster and human spermatozoa. Ultrastructural localization indicated that antigen was predominantly present on the inner face of the outer acrosomal membrane and within the acrosomal content. Qualitative specificity was studied using a highly purified preparation of hamster acrosomes in an enzyme-linked immunosorbent assay. Since the antibody rapidly visualized human acrosomes, it was used to detect abnormal acrosome morphology of mature spermatozoa and to mark spermatids present in the ejaculate. During incubation in capacitating medium, changes in the immunofluorescence of live or methanol fixed spermatozoa were correlated with incubation interval and the ability of spermatozoa to fuse with zona-free hamster oocytes. Spermatozoa bound to zona-free hamster oocytes displayed no fluorescence, confirming that acrosome loss occurred before spermatozoa attached to the vitellus.
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Affiliation(s)
- H D Moore
- MRC/AFRC Comparative Physiology Group, Zoological Society of London, England
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23
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Moore HD, Hartman TD, Bye AP, Lutjen P, De Witt M, Trounson AO. Monoclonal antibody against a sperm antigen Mr 95,000 inhibits attachment of human spermatozoa to the zona pellucida. J Reprod Immunol 1987; 11:157-66. [PMID: 3309284 DOI: 10.1016/0165-0378(87)90054-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
A murine monoclonal antibody raised against hamster spermatozoa was found to cross-react with human spermatozoa. By immunofluorescence, the antigen was visualized over the equatorial segment of human sperm heads. In the presence of antibody, sperm binding to the zona pellucida of salt-stored human oocytes was significantly inhibited (P less than or equal to 0.005) compared with other antibodies or control preparations. Using SDS-PAGE of whole spermatozoa and membrane preparations followed by Western blot analysis, the antigen was identified as a determinant with a relative molecular weight of 95,000.
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Affiliation(s)
- H D Moore
- MRC/AFRC Comparative Physiology Research Group, Zoological Society of London, U.K
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