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Subramaniam S, Kothari H, Bosmann M. Tissue factor in COVID-19-associated coagulopathy. Thromb Res 2022; 220:35-47. [PMID: 36265412 PMCID: PMC9525243 DOI: 10.1016/j.thromres.2022.09.025] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 09/24/2022] [Accepted: 09/28/2022] [Indexed: 11/17/2022]
Abstract
Evidence of micro- and macro-thrombi in the arteries and veins of critically ill COVID-19 patients and in autopsies highlight the occurrence of COVID-19-associated coagulopathy (CAC). Clinical findings of critically ill COVID-19 patients point to various mechanisms for CAC; however, the definitive underlying cause is unclear. Multiple factors may contribute to the prothrombotic state in patients with COVID-19. Aberrant expression of tissue factor (TF), an initiator of the extrinsic coagulation pathway, leads to thrombotic complications during injury, inflammation, and infections. Clinical evidence suggests that TF-dependent coagulation activation likely plays a role in CAC. Multiple factors could trigger abnormal TF expression and coagulation activation in patients with severe COVID-19 infection. Proinflammatory cytokines that are highly elevated in COVID-19 (IL-1β, IL-6 and TNF-α) are known induce TF expression on leukocytes (e.g. monocytes, macrophages) and non-immune cells (e.g. endothelium, epithelium) in other conditions. Antiphospholipid antibodies, TF-positive extracellular vesicles, pattern recognition receptor (PRR) pathways and complement activation are all candidate factors that could trigger TF-dependent procoagulant activity. In addition, coagulation factors, such as thrombin, may further potentiate the induction of TF via protease-activated receptors on cells. In this systematic review, with other viral infections, we discuss potential mechanisms and cell-type-specific expressions of TF during SARS-CoV-2 infection and its role in the development of CAC.
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Sim MM, Banerjee M, Myint T, Garvy BA, Whiteheart SW, Wood JP. Total Plasma Protein S Is a Prothrombotic Marker in People Living With HIV. J Acquir Immune Defic Syndr 2022; 90:463-471. [PMID: 35616596 PMCID: PMC9246910 DOI: 10.1097/qai.0000000000002994] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Accepted: 03/21/2022] [Indexed: 01/30/2023]
Abstract
BACKGROUND HIV-1 infection is associated with multiple procoagulant changes and increased thrombotic risk. Possible mechanisms for this risk include heigthened expression of procoagulant tissue factor (TF) on circulating monocytes, extracellular vesicles, and viral particles and/or acquired deficiency of protein S (PS), a critical cofactor for the anticoagulant protein C (PC). PS deficiency occurs in up to 76% of people living with HIV-1 (PLWH). As increased ex vivo plasma thrombin generation is a strong predictor of mortality, we investigated whether PS and plasma TF are associated with plasma thrombin generation. METHODS We analyzed plasma samples from 9 healthy controls, 17 PLWH on first diagnosis (naive), and 13 PLWH on antiretroviral therapy (ART). Plasma thrombin generation, total and free PS, PC, C4b-binding protein, and TF activity were measured. RESULTS We determined that the plasma thrombin generation assay is insensitive to PS, because of a lack of PC activation, and developed a modified PS-sensitive assay. Total plasma PS was reduced in 58% of the naive and 38% of the ART-treated PLWH samples and correlated with increased thrombin generation in the modified assay. Conversely, plasma TF was not increased in our patient population, suggesting that it does not significantly contribute to ex vivo plasma thrombin generation. CONCLUSION These data suggest that reduced total plasma PS contributes to the thrombotic risk associated with HIV-1 infection and can serve as a prothrombotic biomarker. In addition, our refined thrombin generation assay offers a more sensitive tool to assess the functional consequences of acquired PS deficiency in PLWH.
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Affiliation(s)
- Martha M.S. Sim
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY
| | - Meenakshi Banerjee
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY
| | - Thein Myint
- Division of Infectious Diseases, Department of Internal Medicine, University of Kentucky, Lexington, KY
- Bluegrass Care Clinic, Kentucky Clinic, University of Kentucky, Lexington, KY
| | - Beth A. Garvy
- Department of Microbiology, Immunology and Molecular Genetics, University of Kentucky, Lexington, KY
| | - Sidney W. Whiteheart
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY
- Lexington Veterans’ Affairs Healthcare System, Lexington, KY
| | - Jeremy P. Wood
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY
- Gill Heart and Vascular Institute, Division of Cardiovascular Medicine, Department of Internal Medicine, University of Kentucky, Lexington, KY
- Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY
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3
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Hess CN, Capell WH, Bristow MR, Ruf W, Szarek M, Morrow DA, Nicolau JC, Graybill CA, Marshall D, Hsia J, Bonaca MP. Rationale and design of a study to assess the safety and efficacy of rNAPc2 in COVID-19: the Phase 2b ASPEN-COVID-19 trial. Am Heart J 2022; 246:136-143. [PMID: 34986394 PMCID: PMC8720379 DOI: 10.1016/j.ahj.2021.12.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 12/11/2021] [Accepted: 12/21/2021] [Indexed: 12/22/2022]
Abstract
Background The interaction between thrombosis and inflammation appears central to COVID-19-associated coagulopathy and likely contributes to poor outcomes. Tissue factor is a driver of disordered coagulation and inflammatory signaling in viral infections and is important for viral replication; therefore, tissue factor may be an important therapeutic target in COVID-19. Study Design ASPEN-COVID-19 (NCT04655586) is a randomized, prospective open-label blinded endpoint (PROBE), active comparator Phase 2b trial to evaluate the safety and efficacy of recombinant Nematode Anticoagulant Protein c2 (rNAPc2), a potent tissue factor inhibitor, in patients hospitalized with COVID-19 with elevated D-dimer levels. This report describes the design of the Phase 2b dose ranging and proof of concept study. Participants are randomly assigned, in a 1:1:2 ratio, to lower or higher dose rNAPc2 by subcutaneous injection on days 1, 3, and 5 or to heparin according to local standard of care; randomization is stratified by baseline D-dimer level (at 2X upper limit of normal). The primary efficacy endpoint for Phase 2b is proportional change in D-dimer concentration from baseline to Day 8 or day of discharge, whichever is earlier. The primary safety endpoint is major or non-major clinically relevant bleeding through Day 8. Phase 2b enrollment began in December 2020 and is projected to complete ∼160 participants by Q4 2021. Conclusions ASPEN-COVID-19 will provide important data on a novel therapeutic approach that may improve outcomes in hospitalized COVID-19 patients beyond available anticoagulants by targeting tissue factor, with potential effects on not only thrombosis but also inflammation and viral propagation.
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Qin B, Peng Y, Zhong C, Cai Y, Zhou S, Chen H, Zhuang J, Zeng H, Xu C, Xu H, Li J, Ying G, Gu C, Chen G, Wang L. Mast Cells Mediate Inflammatory Injury and Aggravate Neurological Impairment in Experimental Subarachnoid Hemorrhage Through Microglial PAR-2 Pathway. Front Cell Neurosci 2021; 15:710481. [PMID: 34646122 PMCID: PMC8503547 DOI: 10.3389/fncel.2021.710481] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2021] [Accepted: 08/19/2021] [Indexed: 11/30/2022] Open
Abstract
Subarachnoid hemorrhage (SAH) is a devastating cerebrovascular disease with high mortality and disability. Aberrant neuroinflammation has been identified as a critical factor accounting for the poor prognosis of SAH patients. Mast cells (MCs), the sentinel cells of the immune system, play a critical in the early immune reactions and participate in multiple pathophysiological process. However, the exact role of MCs on the pathophysiological process after SAH has not been fully understood. The current study was conducted to determine the role of MCs and MC stabilization in the context of SAH. Mouse SAH model was established by endovascular perforation process. Mice received saline or cromolyn (MC stabilizer) or compound 48/80 (MCs degranulator). Post-SAH evaluation included neurobehavioral test, western blot, immunofluorescence, and toluidine blue staining. We demonstrated that SAH induced MCs activation/degranulation. Administration of MC stabilizer cromolyn conferred a better neurologic outcome and decreased brain edema when compared with SAH+vehicle group. Furthermore, cromolyn significantly inhibited neuroinflammatory response and alleviated neuronal damage after SAH. However, pharmacological activation of MCs with compound 48/80 dramatically aggravated SAH-induced brain injury and exacerbated neurologic outcomes. Notably, pharmacological inhibition of microglial PAR-2 significantly reversed MCs-induced inflammatory response and neurological impairment. Additionally, the effect of MCs-derived tryptase in mediating neuroinflammation was also abolished by the microglial PAR-2 blockage in vitro. Taken together, MCs yielded inflammatory injury through activating microglia-related neuroinflammation after SAH. These data shed light on the notion that MCs might be a novel and promising therapeutic target for SAH.
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Affiliation(s)
- Bing Qin
- Department of Neurosurgery, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, China
| | - Yucong Peng
- Department of Neurosurgery, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, China
| | - Chen Zhong
- Department of Neurosurgery, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, China
| | - Yong Cai
- Department of Neurosurgery, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, China
| | - Shengjun Zhou
- Department of Neurosurgery, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, China
| | - Huaijun Chen
- Department of Neurosurgery, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, China
| | - Jianfeng Zhuang
- Department of Neurosurgery, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, China
| | - Hanhai Zeng
- Department of Neurosurgery, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, China
| | - Chaoran Xu
- Department of Neurosurgery, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, China
| | - Hangzhe Xu
- Department of Neurosurgery, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, China
| | - Jianru Li
- Department of Neurosurgery, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, China
| | - Guangyu Ying
- Department of Neurosurgery, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, China
| | - Chi Gu
- Department of Neurosurgery, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, China
| | - Gao Chen
- Department of Neurosurgery, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, China
| | - Lin Wang
- Department of Neurosurgery, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, China
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Subramaniam S, Ruf W, Bosmann M. Advocacy of targeting protease-activated receptors in severe coronavirus disease 2019. Br J Pharmacol 2021; 179:2086-2099. [PMID: 34235728 PMCID: PMC8794588 DOI: 10.1111/bph.15587] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 05/19/2021] [Accepted: 05/27/2021] [Indexed: 12/23/2022] Open
Abstract
Identifying drug targets mitigating vascular dysfunction, thrombo-inflammation and thromboembolic complications in COVID-19 is essential. COVID-19 coagulopathy differs from sepsis coagulopathy. Factors that drive severe lung pathology and coagulation abnormalities in COVID-19 are not understood. Protein-protein interaction studies indicate that the tagged viral bait protein ORF9c directly interacts with PAR2, which modulates host cell IFN and inflammatory cytokines. In addition to direct interaction of SARS-CoV-2 viral protein with PARs, we speculate that activation of PAR by proteases plays a role in COVID-19-induced hyperinflammation. In COVID-19-associated coagulopathy elevated levels of activated coagulation proteases may cleave PARs in association with TMPRSS2. PARs activation enhances the release of cytokines, chemokines and tissue factor expression to propagate IFN-dependent inflammation, leukocyte-endothelial interaction, vascular permeability and coagulation responses. This hypothesis, corroborated by in vitro findings and emerging clinical evidence, will focus targeted studies of PAR1/2 blockers as adjuvant drugs against cytokine release syndrome and COVID-19-associated coagulopathy.
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Affiliation(s)
- Saravanan Subramaniam
- Pulmonary Center, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Wolfram Ruf
- Center for Thrombosis and Hemostasis, University Medical Center of the Johannes Gutenberg-University, Mainz, Germany.,Department of Immunology and Microbiology, Scripps Research, La Jolla, California, USA
| | - Markus Bosmann
- Pulmonary Center, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA.,Center for Thrombosis and Hemostasis, University Medical Center of the Johannes Gutenberg-University, Mainz, Germany
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Gülcü O, Aksakal E, Aydemir S, Doğan R, Saraç İ, Aydın SŞ, Öztürk M, Aksu U, Kalkan K, Tanboğa İH. Association between previous anticoagulant use and mortality among hospitalized patients with COVID-19. J Thromb Thrombolysis 2021; 53:88-95. [PMID: 34080103 PMCID: PMC8171228 DOI: 10.1007/s11239-021-02489-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/20/2021] [Indexed: 02/07/2023]
Abstract
Although COVID-19 disease primarily affects the respiratory system, it has been seen in many studies that it causes thromboembolic (TE) events in many tissues and organs. So that, to prevent TE can reduce mortality and morbidity. In this context, this study aimed to investigate the relationship between the previous use of warfarin or other new direct oral anticoagulants (OAC) and mortality in patients hospitalized with a diagnosis of COVID-19 before hospitalization. A total of 5575 patients who were diagnosed with COVID-19 were hospitalized and started treatment between March 21 and November 30, 2020 were included in the study. The primary outcome was in-hospital all-cause mortality. A retrospective cohort study design was planned. Patients were followed up until death or censoring on November 30, 2020. The candidate predictors for primary outcome should be clinically and biologically plausible, and their relationships with all-cause death should be demonstrated in previous studies. We considered all candidate predictors included in the model in accordance with these principles. The main candidate predictor was previous OAC use. The primary analysis method was to compare the time to deaths of patients using and not using previous OAC by a multivariable Cox proportional hazard model (CPHM). In the CPHM, previous OAC use was found to be associated with a significantly lower mortality risk (adjusted hazard ratio 0.62, 95% CI 0.42-0.92, p = 0.030). In hospitalized COVID-19 patients, in patients who previously used anticoagulantswas associated with lower risk of in-hospital death than in those who did not.
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Affiliation(s)
- Oktay Gülcü
- Department of Cardiology, Erzurum Education and Research Hospital, University of Health Sciences, Erzurum, Turkey.
| | - Emrah Aksakal
- Department of Cardiology, Erzurum Education and Research Hospital, University of Health Sciences, Erzurum, Turkey
| | - Selim Aydemir
- Department of Cardiology, Maraşal Çakmak State Hospital, Erzurum, Turkey
| | - Remziye Doğan
- Department of Cardiology, Horasan State Hospital, Erzurum, Turkey
| | - İbrahim Saraç
- Department of Cardiology, Erzurum Education and Research Hospital, University of Health Sciences, Erzurum, Turkey
| | | | - Mustafa Öztürk
- Department of Cardiology, Erzurum Education and Research Hospital, University of Health Sciences, Erzurum, Turkey
| | - Uğur Aksu
- Department of Cardiology, Afyonkarahisar University of Health Science, Afyonkarahisar, Turkey
| | - Kamuran Kalkan
- Department of Cardiology, Erzurum Education and Research Hospital, University of Health Sciences, Erzurum, Turkey
| | - İbrahim Halil Tanboğa
- Department of Cardiology, Hisar Intercontinental Hospital, Nişantaşı University, Istanbul, Turkey
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7
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Conway EM, Pryzdial ELG. Is the COVID-19 thrombotic catastrophe complement-connected? J Thromb Haemost 2020; 18:2812-2822. [PMID: 32762081 PMCID: PMC7436532 DOI: 10.1111/jth.15050] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 07/15/2020] [Accepted: 07/31/2020] [Indexed: 02/06/2023]
Abstract
In December 2019, the world was introduced to a new betacoronavirus, referred to as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) for its propensity to cause rapidly progressive lung damage, resulting in high death rates. As fast as the virus spread, it became evident that the novel coronavirus causes a multisystem disease (COVID-19) that may involve multiple organs and has a high risk of thrombosis associated with striking elevations in pro-inflammatory cytokines, D-dimer, and fibrinogen, but without disseminated intravascular coagulation. Postmortem studies have confirmed the high incidence of venous thromboembolism, but also notably revealed diffuse microvascular thrombi with endothelial swelling, consistent with a thrombotic microangiopathy, and inter-alveolar endothelial deposits of complement activation fragments. The clinicopathologic presentation of COVID-19 thus parallels that of other thrombotic diseases, such as atypical hemolytic uremic syndrome (aHUS), that are caused by dysregulation of the complement system. This raises the specter that many of the thrombotic complications arising from SARS-CoV-2 infections may be triggered and/or exacerbated by excess complement activation. This is of major potential clinical relevance, as currently available anti-complement therapies that are highly effective in protecting against thrombosis in aHUS, could be efficacious in COVID-19. In this review, we provide mounting evidence for complement participating in the pathophysiology underlying the thrombotic diathesis associated with pathogenic coronaviruses, including SARS-CoV-2. Based on current knowledge of complement, coagulation and the virus, we suggest lines of study to identify novel therapeutic targets and the rationale for clinical trials with currently available anti-complement agents for COVID-19.
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Affiliation(s)
- Edward M Conway
- Centre for Blood Research, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Edward L G Pryzdial
- Centre for Blood Research, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
- Canadian Blood Services, Centre for Innovation, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada
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Pryzdial ELG, Sutherland MR, Lin BH, Horwitz M. Antiviral anticoagulation. Res Pract Thromb Haemost 2020; 4:774-788. [PMID: 32685886 PMCID: PMC7354393 DOI: 10.1002/rth2.12406] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 05/28/2020] [Accepted: 06/08/2020] [Indexed: 02/06/2023] Open
Abstract
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a novel envelope virus that causes coronavirus disease 2019 (COVID-19). Hallmarks of COVID-19 are a puzzling form of thrombophilia that has elevated D-dimer but only modest effects on other parameters of coagulopathy. This is combined with severe inflammation, often leading to acute respiratory distress and possible lethality. Coagulopathy and inflammation are interconnected by the transmembrane receptor, tissue factor (TF), which initiates blood clotting as a cofactor for factor VIIa (FVIIa)-mediated factor Xa (FXa) generation. TF also functions from within the nascent TF/FVIIa/FXa complex to trigger profound changes via protease-activated receptors (PARs) in many cell types, including SARS-CoV-2-trophic cells. Therefore, aberrant expression of TF may be the underlying basis of COVID-19 symptoms. Evidence suggests a correlation between infection with many virus types and development of clotting-related symptoms, ranging from heart disease to bleeding, depending on the virus. Since numerous cell types express TF and can act as sites for virus replication, a model envelope virus, herpes simplex virus type 1 (HSV1), has been used to investigate the uptake of TF into the envelope. Indeed, HSV1 and other viruses harbor surface TF antigen, which retains clotting and PAR signaling function. Strikingly, envelope TF is essential for HSV1 infection in mice, and the FXa-directed oral anticoagulant apixaban had remarkable antiviral efficacy. SARS-CoV-2 replicates in TF-bearing epithelial and endothelial cells and may stimulate and integrate host cell TF, like HSV1 and other known coagulopathic viruses. Combined with this possibility, the features of COVID-19 suggest that it is a TFopathy, and the TF/FVIIa/FXa complex is a feasible therapeutic target.
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Affiliation(s)
- Edward L. G. Pryzdial
- Center for InnovationCanadian Blood ServicesVancouverBCCanada
- Centre for Blood Research and Department of Pathology and Laboratory MedicineUniversity of British ColumbiaVancouverBCCanada
| | - Michael R. Sutherland
- Center for InnovationCanadian Blood ServicesVancouverBCCanada
- Centre for Blood Research and Department of Pathology and Laboratory MedicineUniversity of British ColumbiaVancouverBCCanada
| | - Bryan H. Lin
- Center for InnovationCanadian Blood ServicesVancouverBCCanada
- Centre for Blood Research and Department of Pathology and Laboratory MedicineUniversity of British ColumbiaVancouverBCCanada
| | - Marc Horwitz
- Department of Microbiology and ImmunologyUniversity of British ColumbiaVancouverBCCanada
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Lin BH, Sutherland MR, Rosell FI, Morrissey JH, Pryzdial ELG. Coagulation factor VIIa binds to herpes simplex virus 1-encoded glycoprotein C forming a factor X-enhanced tenase complex oriented on membranes. J Thromb Haemost 2020; 18:1370-1380. [PMID: 32145149 PMCID: PMC7647453 DOI: 10.1111/jth.14790] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 01/28/2020] [Accepted: 03/04/2020] [Indexed: 12/28/2022]
Abstract
BACKGROUND The cell membrane-derived initiators of coagulation, tissue factor (TF) and anionic phospholipid (aPL), are constitutive on the herpes simplex virus type 1 (HSV1) surface, bypassing physiological regulation. TF and aPL accelerate proteolytic activation of factor (F) X to FXa by FVIIa to induce clot formation and cell signaling. Thus, infection in vivo is enhanced by virus surface TF. HSV1-encoded glycoprotein C (gC) is implicated in this tenase activity by providing viral FX binding sites and increasing FVIIa function in solution. OBJECTIVE To examine the biochemical influences of gC on FVIIa-dependent FX activation. METHODS Immunogold electron microscopy (IEM), kinetic chromogenic assays and microscale thermophoresis were used to dissect tenase biochemistry. Recombinant TF and gC were solubilized (s) by substituting the transmembrane domain with poly-histidine, which could be orientated on synthetic unilamellar vesicles containing Ni-chelating lipid (Ni-aPL). These constructs were compared to purified HSV1 TF±/gC ± variants. RESULTS IEM confirmed that gC, TF, and aPL are simultaneously expressed on a single HSV1 particle where the contribution of gC to tenase activity required the availability of viral TF. Unlike viral tenase activity, the cofactor effects of sTF and sgC on FVIIa was additive when bound to Ni-aPL. FVIIa was found to bind to sgC and this was enhanced by FX. Orientation of sgC on a lipid membrane was critical for FVIIa-dependent FX activation. CONCLUSIONS The assembly of gC with FVIIa/FX parallels that of TF and may involve other constituents on the HSV1 envelope with implications in virus infection and pathology.
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Affiliation(s)
- Bryan H Lin
- Center for Innovation, Canadian Blood Services, Vancouver, BC, Canada
- Centre for Blood Research and Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Michael R Sutherland
- Center for Innovation, Canadian Blood Services, Vancouver, BC, Canada
- Centre for Blood Research and Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Federico I Rosell
- Centre for Blood Research and Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada
| | - James H Morrissey
- Departments of Biological Chemistry & Internal Medicine, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Edward L G Pryzdial
- Center for Innovation, Canadian Blood Services, Vancouver, BC, Canada
- Centre for Blood Research and Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada
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