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Foley JH, Walton BL, Aleman MM, O'Byrne AM, Lei V, Harrasser M, Foley KA, Wolberg AS, Conway EM. Complement Activation in Arterial and Venous Thrombosis is Mediated by Plasmin. EBioMedicine 2016; 5:175-82. [PMID: 27077125 PMCID: PMC4816834 DOI: 10.1016/j.ebiom.2016.02.011] [Citation(s) in RCA: 93] [Impact Index Per Article: 11.6] [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: 11/03/2015] [Revised: 02/04/2016] [Accepted: 02/05/2016] [Indexed: 12/20/2022] Open
Abstract
Thrombus formation leading to vaso-occlusive events is a major cause of death, and involves complex interactions between coagulation, fibrinolytic and innate immune systems. Leukocyte recruitment is a key step, mediated partly by chemotactic complement activation factors C3a and C5a. However, mechanisms mediating C3a/C5a generation during thrombosis have not been studied. In a murine venous thrombosis model, levels of thrombin–antithrombin complexes poorly correlated with C3a and C5a, excluding a central role for thrombin in C3a/C5a production. However, clot weight strongly correlated with C5a, suggesting processes triggered during thrombosis promote C5a generation. Since thrombosis elicits fibrinolysis, we hypothesized that plasmin activates C5 during thrombosis. In vitro, the catalytic efficiency of plasmin-mediated C5a generation greatly exceeded that of thrombin or factor Xa, but was similar to the recognized complement C5 convertases. Plasmin-activated C5 yielded a functional membrane attack complex (MAC). In an arterial thrombosis model, plasminogen activator administration increased C5a levels. Overall, these findings suggest plasmin bridges thrombosis and the immune response by liberating C5a and inducing MAC assembly. These new insights may lead to the development of strategies to limit thrombus formation and/or enhance resolution. Thrombin is not a major direct contributor to C5a generation during venous thrombosis in mice. Plasmin, a protease generated in response to thrombin generation and fibrin deposition, efficiently cleaves C5 to C5a. In an arterial thrombosis model, administration of a plasminogen activator augments C5a plasma levels. Plasmin participates in immunothrombosis, liberating chemotactic C5a and inducing assembly of the procoagulant C5b-9.
Venous and arterial thrombosis are major causes of death and morbidity. Leukocytes are early and active participants in thrombus formation, recruited partly by complement factor C5a. We examined how C5a is generated in the setting of thrombosis. In venous thrombosis in mice, we show that thrombin, a key clot-promoting enzyme, is not a major contributor to C5a generation. Rather, plasmin, a fibrinolytic enzyme formed in response to thrombin generation and clot formation, efficiently generates C5a. The findings were validated in an arterial thrombosis model in mice. These insights may be valuable in developing therapeutic strategies to limit thrombus formation.
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Key Words
- Complement
- FDP, fibrin degradation product
- FeCl3, ferric chloride
- Fibrinolysis
- IL-8, interleukin-8
- IVC, inferior vena cava
- Leukocytes
- MAC, membrane attack complex
- MCP1-1, monocyte chemoattracant protein-1
- NETs, neutrophil extracellular traps
- PAR1, protease activated receptor 1
- PPACK, Phe-Pro-Arg-chloromethylketone
- R751, arginine 751
- TAT, thrombin antithrombin
- Thrombin
- Thrombosis
- VFKck, Val-Phe-Lys-chloromethylketone
- VWF, von Willebrand factor
- tPA, tissue-type plasminogen activator
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Affiliation(s)
- Jonathan H. Foley
- Centre for Blood Research, Department of Medicine, Life Sciences Institute, University of British Columbia, 2350 Health Sciences Mall, LSC4306, Vancouver V6T 1Z3, Canada
- Department of Haematology, UCL Cancer Institute, University College London, London, United Kingdom
- Katharine Dormandy Haemophilia Centre and Thrombosis Unit, Royal Free NHS Trust, London, United Kingdom
| | - Bethany L. Walton
- Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, 819 Brinkhous-Bullitt Building, CB# 7525, Chapel Hill, NC 27599-7525, USA
| | - Maria M. Aleman
- Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, 819 Brinkhous-Bullitt Building, CB# 7525, Chapel Hill, NC 27599-7525, USA
| | - Alice M. O'Byrne
- Centre for Blood Research, Department of Medicine, Life Sciences Institute, University of British Columbia, 2350 Health Sciences Mall, LSC4306, Vancouver V6T 1Z3, Canada
| | - Victor Lei
- Centre for Blood Research, Department of Medicine, Life Sciences Institute, University of British Columbia, 2350 Health Sciences Mall, LSC4306, Vancouver V6T 1Z3, Canada
| | - Micaela Harrasser
- Department of Haematology, UCL Cancer Institute, University College London, London, United Kingdom
| | - Kimberley A. Foley
- Cancer Care and Epidemiology, Queen's Cancer Research Institute, Queen's University, Kingston, Canada
| | - Alisa S. Wolberg
- Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, 819 Brinkhous-Bullitt Building, CB# 7525, Chapel Hill, NC 27599-7525, USA
| | - Edward M. Conway
- Centre for Blood Research, Department of Medicine, Life Sciences Institute, University of British Columbia, 2350 Health Sciences Mall, LSC4306, Vancouver V6T 1Z3, Canada
- Corresponding author at: Centre for Blood Research, 4306-2350 Health Sciences Mall, University of British Columbia, Vancouver, BC V6T 1Z3, Canada.Centre for Blood Research4306-2350 Health Sciences MallUniversity of British ColumbiaVancouverBCV6T 1Z3Canada
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