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Mutch NJ, Medcalf RL. The fibrinolysis renaissance. J Thromb Haemost 2023; 21:3304-3316. [PMID: 38000850 DOI: 10.1016/j.jtha.2023.09.012] [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: 09/06/2023] [Revised: 09/13/2023] [Accepted: 09/13/2023] [Indexed: 11/26/2023]
Abstract
Fibrinolysis is the system primarily responsible for removal of fibrin deposits and blood clots in the vasculature. The terminal enzyme in the pathway, plasmin, is formed from its circulating precursor, plasminogen. Fibrin is by far the most legendary substrate, but plasmin is notoriously prolific and is known to cleave many other proteins and participate in the activation of other proteolytic systems. Fibrinolysis is often overshadowed by the coagulation system and viewed as a simplistic poorer relation. However, the primordial plasminogen activators evolved alongside the complement system, approximately 70 million years before coagulation saw the light of day. It is highly likely that the plasminogen activation system evolved with its roots in primordial immunity. Almost all immune cells harbor at least one of a dozen plasminogen receptors that allow plasmin formation on the cell surface that in turn modulates immune cell behavior. Similarly, numerous pathogens express their own plasminogen activators or contain surface proteins that provide binding sites for host plasminogen. The fibrinolytic system has been harnessed for clinical medicine for many decades with the development of thrombolytic drugs and antifibrinolytic agents. Our refined understanding and appreciation of the fibrinolytic system and its alliance with infection and immunity and beyond are paving the way for new developments and interest in novel therapeutics and applications. One must ponder as to whether the nomenclature of the system hampered our understanding, by focusing on fibrin, rather than the complex myriad of interactions and substrates of the plasminogen activation system.
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Affiliation(s)
- Nicola J Mutch
- Aberdeen Cardiovascular & Diabetes Centre, Institute of Medical Sciences, School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Foresterhill, Aberdeen, UK.
| | - Robert L Medcalf
- Australian Centre for Blood Diseases, Central Clinical School, Monash University, Melbourne, Victoria, Australia
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Morrow GB, Mutch NJ. Removing plasmin from the equation - Something to chew on…. J Thromb Haemost 2022; 20:280-284. [PMID: 34816576 DOI: 10.1111/jth.15590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Revised: 11/08/2021] [Accepted: 11/10/2021] [Indexed: 11/29/2022]
Affiliation(s)
- Gael B Morrow
- Aberdeen Cardiovascular & Diabetes Centre, Institute of Medical Sciences, School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Aberdeen, UK
- Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Nicola J Mutch
- Aberdeen Cardiovascular & Diabetes Centre, Institute of Medical Sciences, School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Aberdeen, UK
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Mathews NS, Suzuki Y, Honkura N, Sano H, Iwashita T, Urano T. Pre-administration of a carboxypeptidase inhibitor enhances tPA-induced thrombolysis in mouse microthrombi: Evidence from intravital imaging analysis. Thromb Res 2022; 210:78-86. [PMID: 35030422 DOI: 10.1016/j.thromres.2021.12.031] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 12/21/2021] [Accepted: 12/30/2021] [Indexed: 11/28/2022]
Abstract
INTRODUCTION Thrombolysis using recombinant tissue-type plasminogen activator (rt-PA) is the pharmacological treatment of choice in acute thrombotic events. However, a narrow therapeutic window and bleeding complications limit its use. We describe the role of carboxypeptidase inhibitor from potato tuber (PTCI), an inhibitor of activated thrombin-activatable fibrinolysis inhibitor (TAFIa), on Glu-plasminogen accumulation and microthrombus dynamics in vivo and demonstrate its influence on rt-PA-mediated thrombolysis. MATERIALS AND METHODS In conjunction with real-time intravital two-photon excitation fluorescence microscopy, we produced and imaged laser-induced microthrombi in the mesenteric venules of Green Fluorescent Protein (GFP)-expressing mice. We examined microthrombus dynamics and thrombolysis patterns in vivo by measuring the changes in the fluorescence intensity of labeled Glu-plasminogen following administration of epsilon aminocaproic acid (EACA), PTCI, and rt-PA. RESULTS PTCI enhanced Glu-plasminogen accumulation at the core of the thrombus by inhibiting TAFIa, while EACA inhibited this process. Exogenous rt-PA effectively triggered Glu-plasminogen activation within the thrombus and promoted thrombolysis. Administration of PTCI and rt-PA together showed no significant benefit on thrombolysis compared to rt-PA administration alone. However, early-phase systemic administration of PTCI before thrombolytic therapy by rt-PA expedited clot lysis as evidenced by significantly faster time to reach peak Glu-plasminogen fluorescence intensity and shorter time to achieve near-complete clot lysis (P = 0.014 and P = 0.003, respectively). CONCLUSIONS PTCI potentiates rt-PA-mediated thrombolysis when administered early in acute thrombotic events. Further studies are warranted to explore the potential of TAFI inhibitors as adjunct agents in thrombolysis or thromboprophylaxis.
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Affiliation(s)
- Nitty Skariah Mathews
- Department of Medical Physiology, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu city, Shizuoka 431-3192, Japan.
| | - Yuko Suzuki
- Department of Medical Physiology, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu city, Shizuoka 431-3192, Japan.
| | - Naoki Honkura
- Department of Medical Physiology, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu city, Shizuoka 431-3192, Japan.
| | - Hideto Sano
- Department of Medical Physiology, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu city, Shizuoka 431-3192, Japan.
| | - Toshihide Iwashita
- Department of Regenerative & Infectious Pathology, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu city, Shizuoka 431-3192, Japan.
| | - Tetsumei Urano
- Department of Medical Physiology, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu city, Shizuoka 431-3192, Japan; Shizuoka Graduate University of Public Health, 4-17-2, Kita-Ando, Aoi-ku Shizuoka 420-0882, Japan.
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4
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Ilich A, Kumar V, Henderson M, Mallick R, Wells P, Carrier M, Key NS. Biomarkers in cancer patients at risk for venous thromboembolism: data from the AVERT study. Thromb Res 2021; 191 Suppl 1:S31-S36. [PMID: 32736776 DOI: 10.1016/s0049-3848(20)30394-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2019] [Revised: 12/02/2019] [Accepted: 12/09/2019] [Indexed: 12/21/2022]
Abstract
BACKGROUND The mechanisms surrounding cancer-associated venous thromboembolism (VTE) are not well characterized. AVERT, a randomized placebo controlled thromboprophylaxis study in ambulatory cancer patients, provides a unique opportunity to gain insights into thrombotic mechanism(s). METHODS All available citrated platelet-free plasma samples collected at the point of randomization from individuals enrolled in the AVERT study were evaluated for the expression of D-dimer, soluble P-selectin (sP- selectin), active plasminogen activator inhibitor 1 (aPAI-1), clot lysis time (CLT) and activated factor XIa-C1 inhibitor complex (FXIa-C1). We compared the differential expression of sP-selectin, aPAI-1, CLT and FXIa-C1 among individual tumor types with normal controls. We evaluated the impact of disease type (hematologic versus solid organ malignancy) and stage (metastatic versus non-metastatic) on individual biomarker expression. RESULTS We included 449 AVERT participants in this analysis. Baseline expression of the selected thrombosis biomarkers differed significantly by individual tumor type compared with normal controls. Levels of aPAI-1, CLT, FXIa-C1 and sP-selectin were significantly elevated in individuals with lymphoma compared to individuals with non-metastatic solid organ malignancies (p<0.05). Individuals with metastatic solid organ disease had elevated levels of D-dimer and sP-selectin compared to those with non-metastatic disease (p<0.05). CONCLUSION Among a cohort of ambulatory patients at intermediate to high risk of VTE, these exploratory findings suggest that baseline activation of coagulation and fibrinolysis pathways vary significantly by tumor type and disease stage.
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Affiliation(s)
- Anton Ilich
- Department of Medicine, University of North Carolina, Chapel Hill, NC, USA; These authors contributed equally
| | - Vaibhav Kumar
- Department of Medicine, University of North Carolina, Chapel Hill, NC, USA; These authors contributed equally
| | - Michael Henderson
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC, USA
| | - Ranjeeta Mallick
- Department of Medicine, University of Ottawa, Ottawa Hospital Research Institute, Ottawa, Canada
| | - Philip Wells
- Department of Medicine, University of Ottawa, Ottawa Hospital Research Institute, Ottawa, Canada
| | - Marc Carrier
- Department of Medicine, University of Ottawa, Ottawa Hospital Research Institute, Ottawa, Canada
| | - Nigel S Key
- Department of Medicine, University of North Carolina, Chapel Hill, NC, USA; Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC, USA.
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Morrow GB, Whyte CS, Mutch NJ. A Serpin With a Finger in Many PAIs: PAI-1's Central Function in Thromboinflammation and Cardiovascular Disease. Front Cardiovasc Med 2021; 8:653655. [PMID: 33937363 PMCID: PMC8085275 DOI: 10.3389/fcvm.2021.653655] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Accepted: 02/23/2021] [Indexed: 12/27/2022] Open
Abstract
Plasminogen activator inhibitor 1 (PAI-1) is a member of the serine protease inhibitor (serpin) superfamily. PAI-1 is the principal inhibitor of the plasminogen activators, tissue plasminogen activator (tPA), and urokinase-type plasminogen activator (uPA). Turbulence in the levels of PAI-1 tilts the balance of the hemostatic system resulting in bleeding or thrombotic complications. Not surprisingly, there is strong evidence that documents the role of PAI-1 in cardiovascular disease. The more recent uncovering of the coalition between the hemostatic and inflammatory pathways has exposed a distinct role for PAI-1. The storm of proinflammatory cytokines liberated during inflammation, including IL-6 and TNF-α, directly influence PAI-1 synthesis and increase circulating levels of this serpin. Consequently, elevated levels of PAI-1 are commonplace during infection and are frequently associated with a hypofibrinolytic state and thrombotic complications. Elevated PAI-1 levels are also a feature of metabolic syndrome, which is defined by a cluster of abnormalities including obesity, type 2 diabetes, hypertension, and elevated triglyceride. Metabolic syndrome is in itself defined as a proinflammatory state associated with elevated levels of cytokines. In addition, insulin has a direct impact on PAI-1 synthesis bridging these pathways. This review describes the key physiological functions of PAI-1 and how these become perturbed during disease processes. We focus on the direct relationship between PAI-1 and inflammation and the repercussion in terms of an ensuing hypofibrinolytic state and thromboembolic complications. Collectively, these observations strengthen the utility of PAI-1 as a viable drug target for the treatment of various diseases.
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Affiliation(s)
- Gael B Morrow
- Aberdeen Cardiovascular and Diabetes Centre, Institute of Medical Sciences, School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Aberdeen, United Kingdom.,Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Claire S Whyte
- Aberdeen Cardiovascular and Diabetes Centre, Institute of Medical Sciences, School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Aberdeen, United Kingdom
| | - Nicola J Mutch
- Aberdeen Cardiovascular and Diabetes Centre, Institute of Medical Sciences, School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Aberdeen, United Kingdom
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Marta-Enguita J, Navarro-Oviedo M, Muñoz R, Olier-Arenas J, Zalba G, Lecumberri R, Mendioroz M, Paramo JA, Roncal C, Orbe J. Inside the Thrombus: Association of Hemostatic Parameters With Outcomes in Large Vessel Stroke Patients. Front Neurol 2021; 12:599498. [PMID: 33692737 PMCID: PMC7937873 DOI: 10.3389/fneur.2021.599498] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Accepted: 01/14/2021] [Indexed: 01/19/2023] Open
Abstract
Background: Actual clinical management of ischemic stroke (IS) is based on restoring cerebral blood flow using tissue plasminogen activator (tPA) and/or endovascular treatment (EVT). Mechanical thrombectomy has permitted the analysis of thrombus structural and cellular classic components. Nevertheless, histological assessment of hemostatic parameters such as thrombin-activatable fibrinolysis inhibitor (TAFI) and matrix metalloproteinase 10 (MMP-10) remains unknown, although their presence could determine thrombus stability and its response to thrombolytic treatment, improving patient's outcome. Methods: We collected thrombi (n = 45) from large vessel occlusion (LVO) stroke patients (n = 53) and performed a histological analysis of different hemostatic parameters [TAFI, MMP-10, von Willebrand factor (VWF), and fibrin] and cellular components (erythrocytes, leukocytes, macrophages, lymphocytes, and platelets). Additionally, we evaluated the association of these parameters with plasma levels of MMP-10, TAFI and VWF activity and recorded clinical variables. Results: In this study, we report for the first time the presence of MMP-10 and TAFI in all thrombi collected from LVO patients. Both proteins were localized in regions of inflammatory cells, surrounded by erythrocyte and platelet-rich areas, and their content was significantly associated (r = 0.41, p < 0.01). Thrombus TAFI was lower in patients who died during the first 3 months after stroke onset [odds ratio (OR) (95%CI); 0.59 (0.36–0.98), p = 0.043]. Likewise, we observed that thrombus MMP-10 was inversely correlated with the amount of VWF (r = −0.30, p < 0.05). Besides, VWF was associated with the presence of leukocytes (r = 0.37, p < 0.05), platelets (r = 0.32, p < 0.05), and 3 months mortality [OR (95%CI); 4.5 (1.2–17.1), p = 0.029]. Finally, plasma levels of TAFI correlated with circulating and thrombus platelets, while plasma MMP-10 was associated with cardiovascular risk factors and functional dependence at 3 months. Conclusions: The present study suggests that the composition and distribution of thrombus hemostatic components might have clinical impact by influencing the response to pharmacological and mechanical therapies as well as guiding the development of new therapeutic strategies.
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Affiliation(s)
- Juan Marta-Enguita
- Laboratory of Atherothrombosis, CIMA-Universidad de Navarra, Instituto de Investigación Sanitaria de Navarra, IdisNA, Pamplona, Spain.,Neurology Service, Complejo Hospitalario de Navarra, IdisNA, Pamplona, Spain
| | - Manuel Navarro-Oviedo
- Laboratory of Atherothrombosis, CIMA-Universidad de Navarra, Instituto de Investigación Sanitaria de Navarra, IdisNA, Pamplona, Spain
| | - Roberto Muñoz
- Neurology Service, Complejo Hospitalario de Navarra, IdisNA, Pamplona, Spain.,Red de Investigación Cooperativa de Enfermedades Vasculares Cerebrales (INVICTUS PLUS), Madrid, Spain
| | - Jorge Olier-Arenas
- Radiology Service, Complejo Hospitalario de Navarra, IdisNA, Pamplona, Spain
| | - Guillermo Zalba
- Department of Biochemistry and Genetics, University of Navarra, IdiSNA, Pamplona, Spain
| | - Ramon Lecumberri
- Haematology Service, Clínica Universidad de Navarra, Pamplona, Spain
| | - Maite Mendioroz
- Neurology Service, Complejo Hospitalario de Navarra, IdisNA, Pamplona, Spain.,Neuroepigenetics Laboratory-Navarrabiomed, Complejo-Hospitalario de Navarra, Universidad Pública de Navarra-UPNA, IdiSNA, Pamplona, Spain
| | - Jose A Paramo
- Laboratory of Atherothrombosis, CIMA-Universidad de Navarra, Instituto de Investigación Sanitaria de Navarra, IdisNA, Pamplona, Spain.,Haematology Service, Clínica Universidad de Navarra, Pamplona, Spain.,CIBER Cardiovascular (CIBERCV), Instituto de Salud Carlos III, Madrid, Spain
| | - Carmen Roncal
- Laboratory of Atherothrombosis, CIMA-Universidad de Navarra, Instituto de Investigación Sanitaria de Navarra, IdisNA, Pamplona, Spain.,CIBER Cardiovascular (CIBERCV), Instituto de Salud Carlos III, Madrid, Spain
| | - Josune Orbe
- Laboratory of Atherothrombosis, CIMA-Universidad de Navarra, Instituto de Investigación Sanitaria de Navarra, IdisNA, Pamplona, Spain.,CIBER Cardiovascular (CIBERCV), Instituto de Salud Carlos III, Madrid, Spain
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Altered fibrinolysis in autosomal dominant thrombomodulin-associated coagulopathy. Blood 2016; 128:1879-1883. [PMID: 27436851 DOI: 10.1182/blood-2016-05-716092] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Accepted: 07/06/2016] [Indexed: 11/20/2022] Open
Abstract
Thrombomodulin-associated coagulopathy (TM-AC) is a newly recognized dominant bleeding disorder in which a p.Cys537Stop variant in the thrombomodulin (TM) gene THBD, results in high plasma TM levels and protein C-mediated suppression of thrombin generation. Thrombin in complex with TM also activates thrombin-activatable fibrinolysis inhibitor (TAFI). However, the effect of the high plasma TM on fibrinolysis in TM-AC is unknown. Plasma from TM-AC cases and high-TM model control samples spiked with recombinant soluble TM showed reduced tissue factor-induced thrombin generation. Lysis of plasma clots from TM-AC cases was significantly delayed compared with controls but was completely restored when TM/thrombin-mediated TAFI activation was inhibited. Clots formed in blood from TM-AC cases had the same viscoelastic strength as controls but also showed a TAFI-dependent delay in fibrinolysis. Delayed fibrinolysis was reproduced in high-TM model plasma and blood samples. Partial restoration of thrombin generation with recombinant activated factor VII or activated prothrombin complex concentrate did not alter the delayed fibrinolysis in high-TM model blood. Our finding of a previously unrecognized fibrinolytic phenotype indicates that bleeding in TM-AC has a complex pathogenesis and highlights the pivotal role of TM as a regulator of hemostasis.
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Innovative thrombolytic strategy using a heterodimer diabody against TAFI and PAI-1 in mouse models of thrombosis and stroke. Blood 2014; 125:1325-32. [PMID: 25540192 DOI: 10.1182/blood-2014-07-588319] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Circulating thrombin-activatable fibrinolysis inhibitor (TAFI) and plasminogen activator inhibitor-1 (PAI-1) are causal factors for thrombolytic failure. Therefore, we evaluated an antibody-engineered bispecific inhibitor against TAFI and PAI-1 (heterodimer diabody, Db-TCK26D6x33H1F7) in several mouse models of thrombosis and stroke. Prophylactic administration of the diabody (0.8 mg/kg) in a thromboplastin-induced model of thromboembolism led to decreased lung fibrin deposition. In a model of cerebral ischemia and reperfusion, diabody administration (0.8 mg/kg, 1 hour postocclusion) led to a mitigated cerebral injury with a 2.3-fold reduced lesion and improved functional outcomes. In a mouse model of thrombin-induced middle cerebral artery occlusion, the efficacy of the diabody was compared to the standard thrombolytic treatment with recombinant tissue-type plasminogen activator (tPA). Early administration of diabody (0.8 mg/kg) caused a twofold decrease in brain lesion size, whereas that of tPA (10 mg/kg) had a much smaller effect. Delayed administration of diabody or tPA had no effect on lesion size, whereas the combined administration of diabody with tPA caused a 1.7-fold decrease in lesion size. In contrast to tPA, the diabody did not increase accumulative bleeding. In conclusion, administration of a bispecific inhibitor against TAFI and PAI-1 results in a prominent profibrinolytic effect in mice without increased bleeding.
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9
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Wyseure T, Declerck PJ. Novel or expanding current targets in fibrinolysis. Drug Discov Today 2014; 19:1476-82. [PMID: 24886765 DOI: 10.1016/j.drudis.2014.05.025] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Accepted: 05/23/2014] [Indexed: 12/27/2022]
Abstract
Globally the leading cause of long-term disability and mortality stems from cardiovascular diseases, which creates an enormous economic burden. Currently available treatments for intravascular thrombosis consist of a large repertoire of antithrombotic agents targeting coagulation and platelet function. However, the only agents available to enhance fibrinolysis are recombinant or modified forms of plasminogen activators. Their clinical use is limited by low efficacy, life-threatening side-effects (primarily caused by the high systemic dose required) and the inapplicability for prophylactic use. This review provides an update on the latest advances in targeting the antifibrinolytic proteins, plasminogen activator inhibitor-1 and thrombin-activatable fibrinolysis inhibitor, and will highlight novel therapeutic avenues to enhance fibrinolysis.
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Affiliation(s)
- Tine Wyseure
- Laboratory for Therapeutic and Diagnostic Antibodies, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium
| | - Paul J Declerck
- Laboratory for Therapeutic and Diagnostic Antibodies, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium.
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10
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Hendrickx MLV, Zatloukalova M, Hassanzadeh-Ghassabeh G, Muyldermans S, Gils A, Declerck PJ. In vitro and in vivo characterisation of the profibrinolytic effect of an inhibitory anti-rat TAFI nanobody. Thromb Haemost 2014; 111:824-32. [PMID: 24402608 DOI: 10.1160/th13-08-0645] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Accepted: 12/03/2013] [Indexed: 11/05/2022]
Abstract
One of the main disadvantages of current t-PA thrombolytic treatment is the increased bleeding risk. Upon activation, thrombin activatable fibrinolysis inhibitor (TAFI) is a very powerful antifibrinolytic enzyme. Therefore, co-administration of a TAFI inhibitor during thrombolysis could reduce the required t-PA dose without compromising the thrombolytic efficacy. In this study we generated and characterised a nanobody that is inhibitory towards rat TAFI and evaluated its profibrinolytic property in vitro and in vivo. Nanobody VHH-rTAFI-i81 inhibits (at a 16-fold molar ratio nanobody over TAFI) the thrombin/thrombomodulin (T/TM)-mediated activation of rat TAFI (rTAFI) by 83 ± 1.8% with an IC50 of 0.46 (molar ratio nanobody over TAFI). The affinity (KA) of VHH-rTAFI-i81 for rTAFI, as determined by surface plasmon resonance (Biacore®), is 2.5 ± 0.2 x 10(10) M(-1) and illustrates a very strong binding. In an in vitro clot lysis assay, administration of VHH-rTAFI-i81 strongly enhances the degree of lysis and reduces time to reach full lysis of t-PA-mediated clot lysis. Epitope mapping discloses that Lys392 is of primary importance for the nanobody/rTAFI interaction besides minor contributions of Tyr175 and Glu183. In vivo application of VHH-rTAFI-i81 in a tissue factor-induced mouse thromboembolism model significantly decreases fibrin deposition in the lungs in the absence of exogenous administered t-PA. Nanobody VHH-rTAFI-i81 is a very potent inhibitor of T/TM-mediated TAFI activation. Co-administration of this nanobody and t-PA enhances the fibrinolytic efficacy. In an in vivo mouse thromboembolism model, VHH-rTAFI-i81 reduces fibrin deposition in the lungs.
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Affiliation(s)
| | | | | | | | | | - Paul J Declerck
- Paul Declerck, Laboratory for Therapeutic and Diagnostic Antibodies, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Campus Gasthuisberg, O&N2, PB 820, Herestraat 49, B-3000 Leuven, Belgium, Tel.: +32 16 32 34 31, Fax: +32 16 32 34 60, E-mail:
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11
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Wyseure T, Gils A, Declerck PJ. Evaluation of the profibrinolytic properties of a bispecific antibody-based inhibitor against human and mouse thrombin-activatable fibrinolysis inhibitor and plasminogen activator inhibitor-1. J Thromb Haemost 2013; 11:2069-71. [PMID: 24034450 DOI: 10.1111/jth.12399] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Accepted: 08/22/2013] [Indexed: 11/30/2022]
Affiliation(s)
- T Wyseure
- Department of Pharmaceutical and Pharmacological Sciences, Laboratory for Therapeutic and Diagnostic Antibodies, KU Leuven, Leuven, Belgium
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12
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Hendrickx MLV, DE Winter A, Buelens K, Compernolle G, Hassanzadeh-Ghassabeh G, Muyldermans S, Gils A, Declerck PJ. TAFIa inhibiting nanobodies as profibrinolytic tools and discovery of a new TAFIa conformation. J Thromb Haemost 2011; 9:2268-77. [PMID: 21883886 DOI: 10.1111/j.1538-7836.2011.04495.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND Because activated thrombin activatable fibrinolysis inhibitor (TAFIa) has very powerful antifibrinolytic properties, co-administration of t-PA and a TAFIa inhibitor enhances t-PA treatment. OBJECTIVE We aimed to generate nanobodies specifically inhibiting the TAFIa activity and to test their effect on t-PA induced clot lysis. RESULTS Five nanobodies, raised towards an activated more stable TAFIa mutant (TAFIa A(147) -C(305) -I(325) -I(329) -Y(333) -Q(335) ), are described. These nanobodies inhibit specifically TAFIa activity, resulting in an inhibition of up to 99% at a 16-fold molar excess of nanobody over TAFIa, IC(50) 's range between 0.38- and > 16-fold molar excess. In vitro clot lysis experiments in the absence of thrombomodulin (TM) demonstrate that the nanobodies exhibit profibrinolytic effects. However, in the presence of TM, one nanobody exhibits an antifibrinolytic effect whereas the other nanobodies show a slight antifibrinolytic effect at low concentrations and a pronounced profibrinolytic effect at higher concentrations. This biphasic pattern was highly dependent on TM and t-PA concentration. The nanobodies were found to bind in the active-site region of TAFIa and their time-dependent differential binding behavior during TAFIa inactivation revealed the occurrence of a yet unknown intermediate conformational transition. CONCLUSION These nanobodies are very potent TAFIa inhibitors and constitute useful tools to accelerate fibrinolysis. Our data also demonstrate that the profibrinolytic effect of TAFIa inhibition may be reversed by the presence of TM. The identification of a new conformational transition provides new insights into the conformational inactivation of the unstable TAFIa.
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Affiliation(s)
- M L V Hendrickx
- Laboratory for Pharmaceutical Biology, Faculty of Pharmaceutical Sciences, Katholieke Universiteit Leuven, Leuven, Belgium
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Luo D, Szaba FM, Kummer LW, Plow EF, Mackman N, Gailani D, Smiley ST. Protective roles for fibrin, tissue factor, plasminogen activator inhibitor-1, and thrombin activatable fibrinolysis inhibitor, but not factor XI, during defense against the gram-negative bacterium Yersinia enterocolitica. THE JOURNAL OF IMMUNOLOGY 2011; 187:1866-76. [PMID: 21724997 DOI: 10.4049/jimmunol.1101094] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Septic infections dysregulate hemostatic pathways, prompting coagulopathy. Nevertheless, anticoagulant therapies typically fail to protect humans from septic pathology. The data reported in this work may help to explain this discrepancy by demonstrating critical protective roles for coagulation leading to fibrin deposition during host defense against the Gram-negative bacterium Yersinia enterocolitica. After i.p. inoculation with Y. enterocolitica, fibrinogen-deficient mice display impaired cytokine and chemokine production in the peritoneal cavity and suppressed neutrophil recruitment. Moreover, both gene-targeted fibrinogen-deficient mice and wild-type mice treated with the anticoagulant coumadin display increased hepatic bacterial burden and mortality following either i.p. or i.v. inoculation with Y. enterocolitica. Mice with low tissue factor activity succumb to yersiniosis with a phenotype similar to fibrin(ogen)-deficient mice, whereas factor XI-deficient mice show wild-type levels of resistance. Mice deficient in plasminogen activator inhibitor-1 or thrombin-activatable fibrinolysis inhibitor display modest phenotypes, but mice deficient in both plasminogen activator inhibitor-1 and thrombin-activatable fibrinolysis inhibitor succumb to yersiniosis with a phenotype resembling fibrin(ogen)-deficient mice. These findings demonstrate critical protective roles for the tissue factor-dependent extrinsic coagulation pathway during host defense against bacteria and caution that therapeutics targeting major thrombin-generating or antifibrinolytic pathways may disrupt fibrin-mediated host defense during Gram-negative sepsis.
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Affiliation(s)
- Deyan Luo
- Trudeau Institute, Saranac Lake, NY 12983, USA
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Evaluation of the profibrinolytic properties of an anti-TAFI monoclonal antibody in a mouse thromboembolism model. Blood 2011; 117:4615-22. [PMID: 21343611 DOI: 10.1182/blood-2010-08-303677] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The enhancement of fibrinolysis constitutes a promising approach to treat thrombotic diseases. Activated thrombin activatable fibrinolysis inhibitor (TAFIa) attenuates fibrinolysis and is an attractive target to develop profibrinolytic drugs. TAFI can be activated by thrombin, thrombin/thrombomodulin, or plasmin, but the in vivo physiologic TAFI activator(s) are unknown. Here, we generated and characterized MA-TCK26D6, a monoclonal antibody raised against human TAFI, and examined its profibrinolytic properties in vitro and in vivo. In vitro, MA-TCK26D6 showed a strong profibrinolytic effect caused by inhibition of the plasmin-mediated TAFI activation. In vivo, MA-TCK26D6 significantly decreased fibrin deposition in the lungs of thromboembolism-induced mice. Moreover, in the presence of MA-TCK26D6, plasmin-α(2)-antiplasmin complexes in plasma of thromboembolism-induced mice were significantly increased compared with a control antibody, indicative of an acceleration of fibrinolysis through MA-TCK26D6. In this study, we show that plasmin is an important TAFI activator that hampers in vitro clot lysis. Furthermore, this is the first report on an anti-TAFI monoclonal antibody that demonstrates a strong profibrinolytic effect in a mouse thromboembolism model.
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Buelens K, Hassanzadeh-Ghassabeh G, Muyldermans S, Gils A, Declerck PJ. Generation and characterization of inhibitory nanobodies towards thrombin activatable fibrinolysis inhibitor. J Thromb Haemost 2010; 8:1302-12. [PMID: 20180900 DOI: 10.1111/j.1538-7836.2010.03816.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
BACKGROUND AND OBJECTIVE As activated thrombin-activatable fibrinolysis inhibitor (TAFIa) is a potent antifibrinolytic enzyme, the development of TAFI inhibitors is a new promising approach in the development of profibrinolytic drugs. We, therefore, aimed to generate nanobodies, camelid-derived single-domain antibodies towards TAFI. METHODS AND RESULTS This study reports the generation and characterization of a panel of 22 inhibitory nanobodies. This panel represents a wide diversity in mechanisms for interference with the functional properties of TAFI as the nanobodies interfere with various modes of TAFI activation, TAFIa activity and/or TAFI zymogen activity. Nanobodies inhibiting TAFIa activity and thrombin/thrombomodulin-mediated TAFI activation revealed profibrinolytic properties in a clot lysis experiment with exogenously added thrombomodulin (TM), whereas nanobodies inhibiting plasmin-mediated TAFI activation only revealed profibrinolytic properties in a clot lysis experiment without TM. The results of in vitro clot lysis experiments provided evidence that inhibitory nanobodies penetrate the clot better compared with inhibitory monoclonal antibodies. CONCLUSIONS These data suggest that the generated nanobodies are potent TAFI inhibitors and are a step forward in the development of a profibrinolytic drug. They might also be an excellent tool to unravel the role of the physiological activators of TAFI in various pathophysiological processes.
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Affiliation(s)
- K Buelens
- Laboratory for Pharmaceutical Biology, Faculty of Pharmaceutical Sciences, Katholieke Universiteit Leuven, Leuven, Belgium
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