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Hassan S, Baselli G, Mollica L, Rossi RL, Chand H, El-Beshlawy A, Elalfy M, Ramanan V, Eshghi P, Karimi M, Palla R, Rosendaal FR, Peyvandi F. Predicting inhibitor development using a random peptide phage-display library approach in the SIPPET cohort. Blood Adv 2024; 8:2880-2889. [PMID: 38593222 PMCID: PMC11176960 DOI: 10.1182/bloodadvances.2023011388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Revised: 03/28/2024] [Accepted: 03/28/2024] [Indexed: 04/11/2024] Open
Abstract
ABSTRACT Inhibitor development is the most severe complication of hemophilia A (HA) care and is associated with increased morbidity and mortality. This study aimed to use a novel immunoglobulin G epitope mapping method to explore the factor VIII (FVIII)-specific epitope profile in the SIPPET cohort population and to develop an epitope mapping-based inhibitor prediction model. The population consisted of 122 previously untreated patients with severe HA who were followed up for 50 days of exposure to FVIII or 3 years, whichever occurred first. Sampling was performed before FVIII treatment and at the end of the follow-up. The outcome was inhibitor development. The FVIII epitope repertoire was assessed by means of a novel random peptide phage-display assay. A least absolute shrinkage and selection operator (LASSO) regression model and a random forest model were fitted on posttreatment sample data and validated in pretreatment sample data. The predictive performance of these models was assessed by the C-statistic and a calibration plot. We identified 27 775 peptides putatively directed against FVIII, which were used as input for the statistical models. The C-statistic of the LASSO and random forest models were good at 0.78 (95% confidence interval [CI], 0.69-0.86) and 0.80 (95% CI, 0.72-0.89). Model calibration of both models was moderately good. Two statistical models, developed on data from a novel random peptide phage display assay, were used to predict inhibitor development before exposure to exogenous FVIII. These models can be used to set up diagnostic tests that predict the risk of inhibitor development before starting treatment with FVIII.
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Affiliation(s)
- Shermarke Hassan
- Department of Pathophysiology and Transplantation, Università degli Studi di Milano, Milan, Italy
- Department of Clinical Epidemiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Guido Baselli
- Department of Transfusion Medicine and Hematology, Translational Medicine, Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Luca Mollica
- Department of Medical Biotechnologies and Translational Medicine, LITA/University of Milan, Milan, Italy
| | - Riccardo L. Rossi
- Bioinformatics, Istituto Nazionale Genetica Molecolare “Romeo ed Enrica Invernizzi,” Milan, Italy
| | - Himani Chand
- Department of Pathophysiology and Transplantation, Università degli Studi di Milano, Milan, Italy
| | - Amal El-Beshlawy
- Pediatric Hematology Department, Cairo University Pediatric Hospital, Cairo, Egypt
| | - Mohsen Elalfy
- Faculty of Medicine, Ain Shams University, Department of Pediatrics, Cairo, Egypt
| | - Vijay Ramanan
- Department of Hematology, Jehangir Clinical Development Centre, Jehangir Hospital Premises, Pune, India
| | - Peyman Eshghi
- Congenital Pediatric Hematologic Disorders Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Mehran Karimi
- Pediatric Hematology-Oncology Department, American Hospital Dubai, Dubai, United Arab Emirates
| | - Roberta Palla
- Department of Pathophysiology and Transplantation, Università degli Studi di Milano, Milan, Italy
| | - Frits R. Rosendaal
- Department of Clinical Epidemiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Flora Peyvandi
- Department of Pathophysiology and Transplantation, Università degli Studi di Milano, Milan, Italy
- Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, Milan, Italy
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Mizumachi K, Nakajima Y, Shimonishi N, Furukawa S, Ogiwara K, Takeyama M, Nogami K. Hybrid human-porcine factor VIII proteins partially escape the inhibitory effects of anti-factor VIII inhibitor alloantibodies having A2 or C2 domain specificity. Haemophilia 2024; 30:140-150. [PMID: 38058226 DOI: 10.1111/hae.14911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 10/29/2023] [Accepted: 11/28/2023] [Indexed: 12/08/2023]
Abstract
INTRODUCTION Porcine factor (pF)VIII has low cross-reactivity with anti-human (h)FVIII inhibitor alloantibodies. Clinical trials of pFVIII in congenital haemophilia A patients with inhibitor (PwHA-I) are in progress. Most polyclonal anti-hFVIII inhibitors recognize its A2 and/or C2 domain(s), and recombinant human-porcine hybrid (hp)FVIII proteins may escape neutralization by these inhibitors. AIM To evaluate the ability of hpFVIII to limit the anti-FVIII activity of inhibitor alloantibodies. METHODS Three hybrid proteins were created by substituting the hFVIII A2, C2 domain or both with the corresponding domains of pFVIII [termed hp(A2), hp(C2) and hp(A2/C2), respectively]. The reactivity of these hybrids was assessed by one-stage clotting assays (OSA), thrombin generation assays (TGA) and rotational thromboelastometry (ROTEM) by adding them to FVIII-deficient samples. RESULTS OSA demonstrated that the hybrid proteins avoided neutralization by anti-FVIII A2 or C2 monoclonal antibodies (mAb) and polyclonal inhibitor-antibodies (polyAb) from PwHA-I. In TGA, thrombin generation with hp(A2) and hp(A2/C2) was not attenuated in the presence of patient IgG recognizing anti-A2 domain. In contrast, that with hFVIII and hp(C2) was suppressed by this IgG to levels equivalent to those of FVIII-deficient plasma. With anti-A2/C2 polyAb, the activity of hp(A2/C2) was unaffected. ROTEM demonstrated that the addition of hp(A2) or hp(A2/C2) to anti-A2 polyAb shortened clot times/clot formation times, whilst hFVIII or hp(C2) were ineffective. Similarly with anti-A2/C2 polyAb, hp(A2/C2) restored coagulation potential to a greater extent than hp(A2) and hp(C2). CONCLUSION Hybrid FVIII proteins containing porcine FVIII A2 and/or C2 domain(s) could support effective therapy in PwHA-I by avoiding neutralization.
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Affiliation(s)
| | - Yuto Nakajima
- Department of Pediatrics, Nara Medical University, Kashihara, Nara, Japan
- Advanced Medical Science of Thrombosis and Hemostasis, Nara Medical University, Kashihara, Nara, Japan
| | - Naruto Shimonishi
- Department of Pediatrics, Nara Medical University, Kashihara, Nara, Japan
- The Course of Thrombosis and Hemostasis Molecular Pathology, Nara Medical University, Kashihara, Nara, Japan
| | - Shoko Furukawa
- Department of Pediatrics, Nara Medical University, Kashihara, Nara, Japan
| | - Kenichi Ogiwara
- Department of Pediatrics, Nara Medical University, Kashihara, Nara, Japan
| | - Masahiro Takeyama
- Department of Pediatrics, Nara Medical University, Kashihara, Nara, Japan
| | - Keiji Nogami
- Department of Pediatrics, Nara Medical University, Kashihara, Nara, Japan
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Bashar S, Jeong HJ. Bacterial Production of Recombinant Coagulation Factor VIII Domains. MEDICINA (KAUNAS, LITHUANIA) 2023; 59:694. [PMID: 37109652 PMCID: PMC10143837 DOI: 10.3390/medicina59040694] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Revised: 03/24/2023] [Accepted: 03/30/2023] [Indexed: 04/05/2023]
Abstract
Factor VIII (F8) is a blood coagulation protein prearranged in six domains, and its deficiency causes hemophilia A. To fashion functional F8 therapeutics, development of a recombinant F8 (rF8) domain is essential not only for F8 substitution, but also to decipher the F8-related mechanisms. In this study, we generated Glutathione S-transferase (GST)-conjugated recombinant A2 and A3 domains of F8 using Escherichia coli. The high growth rate and economically advantageous protein production system in terms of inexpensive reagents and materials in E. coli cells facilitated the completion of entire process from protein expression to purification in 3-4 days with low production cost. Subsequent assessment of these purified proteins using enzyme-linked immunosorbent assay (ELISA) and antibodies against F8 revealed enhanced detection of rF8-A2 or rF8-A3 in a concentration dependent manner, indicating the presence of the antibody-binding epitopes in these proteins. Furthermore, these proteins are suitable for generating novel antibodies against the F8 domain and F8 domain-capturing affinity columns by enabling their conjugation to GST-capturing beads. Additionally, the recombinant F8 domains produced herein can be used for various studies, which include investigating the explicit roles of the F8 domain in the coagulation process, with domain-specific binding partners, and antibodies.
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Affiliation(s)
- Saima Bashar
- Industry-Academia Cooperation Foundation, Hongik University, 2639 Sejong-ro, Sejong-si 30016, Republic of Korea
| | - Hee-Jin Jeong
- Department of Biological and Chemical Engineering, Hongik University, 2639 Sejong-ro, Sejong-si 30016, Republic of Korea
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van Galen J, Freato N, Przeradzka MA, Ebberink EHTM, Boon-Spijker M, van der Zwaan C, van den Biggelaar M, Meijer AB. Hydrogen-Deuterium Exchange Mass Spectrometry Identifies Activated Factor IX-Induced molecular Changes in Activated Factor VIII. Thromb Haemost 2020; 121:594-602. [PMID: 33302303 DOI: 10.1055/s-0040-1721422] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Hydrogen-deuterium exchange mass spectrometry (HDX-MS) was employed to gain insight into the changes in factor VIII (FVIII) that occur upon its activation and assembly with activated factor IX (FIXa) on phospholipid membranes. HDX-MS analysis of thrombin-activated FVIII (FVIIIa) revealed a marked increase in deuterium incorporation of amino acid residues along the A1-A2 and A2-A3 interface. Rapid dissociation of the A2 domain from FVIIIa can explain this observation. In the presence of FIXa, enhanced deuterium incorporation at the interface of FVIIIa was similar to that of FVIII. This is compatible with the previous finding that FIXa contributes to A2 domain retention in FVIIIa. A2 domain region Leu631-Tyr637, which is not part of the interface between the A domains, also showed a marked increase in deuterium incorporation in FVIIIa compared with FVIII. Deuterium uptake of this region was decreased in the presence of FIXa beyond that observed in FVIII. This implies that FIXa alters the conformation or directly interacts with this region in FVIIIa. Replacement of Val634 in FVIII by alanine using site-directed mutagenesis almost completely impaired the ability of the activated cofactor to enhance the activity of FIXa. Surface plasmon resonance analysis revealed that the rates of A2 domain dissociation from FVIIIa and FVIIIa-Val634Ala were indistinguishable. HDX-MS analysis showed, however, that FIXa was unable to retain the A2 domain in FVIIIa-Val634Ala. The combined results of this study suggest that the local structure of Leu631-Tyr637 is altered by FIXa and that this region contributes to the cofactor function of FVIII.
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Affiliation(s)
- Josse van Galen
- Department of Molecular and Cellular Hemostasis, Sanquin Research, Amsterdam, The Netherlands
| | - Nadia Freato
- Department of Molecular and Cellular Hemostasis, Sanquin Research, Amsterdam, The Netherlands
| | - Małgorzata A Przeradzka
- Department of Molecular and Cellular Hemostasis, Sanquin Research, Amsterdam, The Netherlands
| | - Eduard H T M Ebberink
- Department of Molecular and Cellular Hemostasis, Sanquin Research, Amsterdam, The Netherlands
| | - Mariëtte Boon-Spijker
- Department of Molecular and Cellular Hemostasis, Sanquin Research, Amsterdam, The Netherlands
| | - Carmen van der Zwaan
- Department of Molecular and Cellular Hemostasis, Sanquin Research, Amsterdam, The Netherlands
| | | | - Alexander B Meijer
- Department of Molecular and Cellular Hemostasis, Sanquin Research, Amsterdam, The Netherlands.,Department of Biomolecular Mass Spectrometry and Proteomics, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands
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Brettschneider K, Schmidt A, Kahle J, Orlowski A, Stichel D, Schwabe D, Königs C. Elimination of factor VIII-specific B cells by immunotoxins composed of a single factor VIII domain fused to Pseudomonas exotoxin A. J Thromb Haemost 2018; 16:2223-2232. [PMID: 30152083 DOI: 10.1111/jth.14273] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Indexed: 01/19/2023]
Abstract
Essentials There is still a need for novel therapeutic approaches for hemophilia A patients with inhibitors. A factor VIII domain was used as the targeting moiety for elimination of FVIII-specific B cells. The immunodominant C2 domain was fused to exotoxin A from Pseudomonas aeruginosa (hC2-ETA). Murine C2 domain-specific B cells were selectively and efficiently eliminated by hC2-ETA ex vivo. SUMMARY: Background Today, the most serious complication for patients with hemophilia A undergoing factor VIII (FVIII) replacement therapy is the development of neutralizing antibodies (inhibitors). Although inhibitors can be eradicated by application of high doses of FVIII, the immune tolerance induction therapy fails in up to 30% of patients. Hence, there is still an urgent need for novel therapeutic approaches for patients with persisting inhibitors. Objectives In the present study, the potential use of immunotoxins containing exotoxin A (ETA) from Pseudomonas aeruginosa for selective elimination of FVIII-specific B cells was explored. Methods The immunodominant C2 domain of human FVIII was used as a targeting moiety instead of the full-length FVIII protein and the resulting human C2 domain-ETA fusion protein (hC2-ETA) was produced in Escherichia coli. Results Binding studies with monoclonal C2 domain-specific antibodies confirmed the conformational integrity of the C2 domain in hC2-ETA. The functionality of hC2-ETA was tested ex vivo by incubation of splenocytes from inhibitor-positive FVIII knockout mice with hC2-ETA and controls. FVIII-specific memory B cells from splenocytes were differentiated by FVIII stimulation in antibody-secreting cells (ASC) and detected by an enzyme-linked immunospot assay. Although the controls showed no effect, incubation of splenocytes with hC2-ETA reduced the number of C2-specific ASC in a dose-dependent fashion, indicating specific and efficient elimination of C2-specific memory B cells. Conclusions Overall, the results of the study support the fact that FVIII domain immunotoxins might be a potential new tool for the elimination of FVIII-specific B cells in patients with hemophilia A and persisting inhibitors.
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Affiliation(s)
- K Brettschneider
- Department of Pediatrics and Adolescent Medicine, University Hospital, Goethe University, Frankfurt am Main, Germany
- Faculty of Biological Science, Goethe University, Frankfurt am Main, Germany
| | - A Schmidt
- Department of Pediatrics and Adolescent Medicine, University Hospital, Goethe University, Frankfurt am Main, Germany
| | - J Kahle
- Department of Pediatrics and Adolescent Medicine, University Hospital, Goethe University, Frankfurt am Main, Germany
| | - A Orlowski
- Department of Pediatrics and Adolescent Medicine, University Hospital, Goethe University, Frankfurt am Main, Germany
| | - D Stichel
- Department of Pediatrics and Adolescent Medicine, University Hospital, Goethe University, Frankfurt am Main, Germany
| | - D Schwabe
- Department of Pediatrics and Adolescent Medicine, University Hospital, Goethe University, Frankfurt am Main, Germany
| | - C Königs
- Department of Pediatrics and Adolescent Medicine, University Hospital, Goethe University, Frankfurt am Main, Germany
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6
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Deng W, Wang Y, Druzak SA, Healey JF, Syed AK, Lollar P, Li R. A discontinuous autoinhibitory module masks the A1 domain of von Willebrand factor. J Thromb Haemost 2017; 15:1867-1877. [PMID: 28692141 PMCID: PMC5585049 DOI: 10.1111/jth.13775] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Indexed: 12/18/2022]
Abstract
Essentials The mechanism for the auto-inhibition of von Willebrand factor (VWF) remains unclear. Hydrogen exchange of two VWF A1 fragments with disparate activities was measured and compared. Discontinuous residues flanking A1 form a structural module that blocks A1 binding to the platelet. Our results suggest a potentially unified model of VWF activation. Click to hear an ISTH Academy presentation on the domain architecture of VWF and activation by elongational flow by Dr Springer SUMMARY: Background How von Willebrand factor (VWF) senses and responds to shear flow remains unclear. In the absence of shear flow, VWF or its fragments can be induced to bind spontaneously to platelet GPIbα. Objectives To elucidate the auto-inhibition mechanism of VWF. Methods Hydrogen-deuterium exchange (HDX) of two recombinant VWF fragments expressed from baby hamster kidney cells were measured and compared. Results The shortA1 protein contains VWF residues 1261-1472 and binds GPIbα with a significantly higher affinity than the longA1 protein that contains VWF residues 1238-1472. Both proteins contain the VWF A1 domain (residues 1272-1458). Many residues in longA1, particularly those in the N- and C-terminal sequences flanking the A1 domain, and in helix α1, loops α1β2 and β3α2, demonstrated markedly reduced HDX compared with their counterparts in shortA1. The HDX-protected region in longA1 overlaps with the GPIbα-binding interface and is clustered with type 2B von Willebrand disease (VWD) mutations. Additional comparison with the HDX of denatured longA1 and ristocetin-bound longA1 indicates the N- and C-terminal sequences flanking the A1 domain form cooperatively an integrated autoinhibitory module (AIM) that interacts with the HDX-protected region. Binding of ristocetin to the C-terminal part of the AIM desorbs the AIM from A1 and enables longA1 binding to GPIbα. Conclusion The discontinuous AIM binds the A1 domain and prevents it from binding to GPIbα, which has significant implications for the pathogenesis of type 2B VWD and the shear-induced activation of VWF activity.
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Affiliation(s)
- W Deng
- Aflac Cancer and Blood Disorders Center, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, USA
| | - Y Wang
- Aflac Cancer and Blood Disorders Center, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, USA
| | - S A Druzak
- Aflac Cancer and Blood Disorders Center, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, USA
| | - J F Healey
- Aflac Cancer and Blood Disorders Center, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, USA
| | - A K Syed
- Aflac Cancer and Blood Disorders Center, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, USA
| | - P Lollar
- Aflac Cancer and Blood Disorders Center, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, USA
| | - R Li
- Aflac Cancer and Blood Disorders Center, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, USA
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Frequency and epitope specificity of anti-factor VIII C1 domain antibodies in acquired and congenital hemophilia A. Blood 2017; 130:808-816. [PMID: 28507083 DOI: 10.1182/blood-2016-11-751347] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 04/16/2017] [Indexed: 12/28/2022] Open
Abstract
Several studies showed that neutralizing anti-factor VIII (anti-fVIII) antibodies (inhibitors) in patients with acquired hemophilia A (AHA) and congenital hemophilia A (HA) are primarily directed to the A2 and C2 domains. In this study, the frequency and epitope specificity of anti-C1 antibodies were analyzed in acquired and congenital hemophilia inhibitor patients (n = 178). The domain specificity of antibodies was studied by homolog-scanning mutagenesis (HSM) with single human domain human/porcine fVIII proteins and antibody binding to human A2, C1, and C2 domains presented as human serum albumin (HSA) fusion proteins. The analysis with HSA-fVIII domain proteins confirmed the results of the HSM approach but resulted in higher detection levels. The higher detection levels with HSA-fVIII domain proteins are a result of antibody cross-reactivity with human and porcine fVIII leading to false-negative HSM results. Overall, A2-, C1-, and C2-specific antibodies were detected in 23%, 78%, and 68% of patients with AHA (n = 115) and in 52%, 57%, and 81% of HA inhibitor patients (n = 63). Competitive binding of the human monoclonal antibody (mAb) LE2E9 revealed overlapping epitopes with murine C1-specific group A mAbs including 2A9. Mutational analyses identified distinct crucial binding residues for LE2E9 (E2066) and 2A9 (F2068) that are also recognized by anti-C1 antibodies present in patients with hemophilia. A strong contribution of LE2E9- and 2A9-like antibodies was particularly observed in patients with AHA. Overall, our study demonstrates that the C1 domain, in addition to the A2 and C2 domains, contributes significantly to the humoral anti-fVIII immune response in acquired and congenital hemophilia inhibitor patients.
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Evans MS, Donaldson KJ, Eyster ME. Development of a novel automated screening method for detection of FVIII Inhibitors. Int J Lab Hematol 2017; 39:185-190. [PMID: 28133956 DOI: 10.1111/ijlh.12601] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 09/23/2016] [Indexed: 11/28/2022]
Abstract
INTRODUCTION Factor VIII activity is routinely determined by measuring the activated partial thromboplastin time (aPTT) of a patient plasma sample and determining percent activity from a standard curve. To maximize the detection of a clotting factor inhibitor, a subjective assessment of parallelism of a patient curve compared with a standard curve is performed. We developed and validated an automated objective method to assess parallelism as a rapid screening tool for detection of an inhibitor to factor VIII during routine FVIII assays. METHODS We performed FVIII assays on a subset of FVIII-deficient patients with hemophilia A with and without inhibitors. Utilizing a ratio of the slopes from parallelism curves obtained by an independent Microsoft excel program in patients compared with a normal standard curve, we determined a cutoff ratio predictive for presence of an inhibitor. RESULTS A cutoff ratio of patient to control slopes of <0.45 for the detection of an inhibitor to FVIII was 100% sensitive and 91.6% specific, with a positive predictive value of 92.3% and a negative predictive value of 100%. CONCLUSION Utilizing a ratio of the slopes from parallelism curves in patients with and without an inhibitor, we developed and validated a rapid, automated, and objective method to assess parallelism as an added screening tool for detection of an inhibitor to factor VIII during routine FVIII assays on a STAGO-based coagulation platform. This simple automated method has the potential to detect inhibitors to other clotting factors.
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Affiliation(s)
- M S Evans
- Department of Medicine, Division of Hematology/Oncology, Penn State Health-Milton S. Hershey Medical Center, Hershey, PA, USA
| | - K J Donaldson
- Department of Biochemistry and Molecular Biology, Penn State Health-Milton S. Hershey Medical Center, Hershey, PA, USA
| | - M E Eyster
- Department of Medicine, Division of Hematology/Oncology, Penn State Health-Milton S. Hershey Medical Center, Hershey, PA, USA
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Kahle J, Orlowski A, Stichel D, Healey JF, Parker ET, Donfield SM, Astermark J, Berntorp E, Lollar P, Schwabe D, Königs C. Anti-factor VIII antibodies in brothers with haemophilia A share similar characteristics. Haemophilia 2016; 23:292-299. [DOI: 10.1111/hae.13105] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/22/2016] [Indexed: 12/19/2022]
Affiliation(s)
- J. Kahle
- Department of Paediatrics; Clinical and Molecular Haemostasis and Immunodeficiency; University Hospital Frankfurt; Frankfurt am Main Germany
| | - A. Orlowski
- Department of Paediatrics; Clinical and Molecular Haemostasis and Immunodeficiency; University Hospital Frankfurt; Frankfurt am Main Germany
| | - D. Stichel
- Department of Paediatrics; Clinical and Molecular Haemostasis and Immunodeficiency; University Hospital Frankfurt; Frankfurt am Main Germany
| | - J. F. Healey
- Department of Pediatrics; Aflac Cancer and Blood Disorders Center; Children's Healthcare of Atlanta and Emory University; Atlanta GA USA
| | - E. T. Parker
- Department of Pediatrics; Aflac Cancer and Blood Disorders Center; Children's Healthcare of Atlanta and Emory University; Atlanta GA USA
| | - S. M. Donfield
- Department of Biostatistics; Rho Inc.; Chapel Hill NC USA
| | - J. Astermark
- Centre for Thrombosis and Haemostasis; Lund University; Skåne University Hospital; Malmö Sweden
| | - E. Berntorp
- Centre for Thrombosis and Haemostasis; Lund University; Skåne University Hospital; Malmö Sweden
| | - P. Lollar
- Department of Pediatrics; Aflac Cancer and Blood Disorders Center; Children's Healthcare of Atlanta and Emory University; Atlanta GA USA
| | - D. Schwabe
- Department of Paediatrics; Clinical and Molecular Haemostasis and Immunodeficiency; University Hospital Frankfurt; Frankfurt am Main Germany
| | - C. Königs
- Department of Paediatrics; Clinical and Molecular Haemostasis and Immunodeficiency; University Hospital Frankfurt; Frankfurt am Main Germany
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Young PA, Migliorini M, Strickland DK. Evidence That Factor VIII Forms a Bivalent Complex with the Low Density Lipoprotein (LDL) Receptor-related Protein 1 (LRP1): IDENTIFICATION OF CLUSTER IV ON LRP1 AS THE MAJOR BINDING SITE. J Biol Chem 2016; 291:26035-26044. [PMID: 27794518 DOI: 10.1074/jbc.m116.754622] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Revised: 10/25/2016] [Indexed: 11/06/2022] Open
Abstract
Hemophilia A is a bleeding disorder caused by a deficiency in coagulation factor VIII (fVIII) that affects 1 in 5,000 males. Current prophylactic replacement therapy, although effective, is difficult to maintain due to the cost and frequency of injections. Hepatic clearance of fVIII is mediated by the LDL receptor-related protein 1 (LRP1), a member of the LDL receptor family. Although it is well established that fVIII binds LRP1, the molecular details of this interaction are unclear as most of the studies have been performed using fragments of fVIII and LRP1. In the current investigation, we examine the binding of intact fVIII to full-length LRP1 to gain insight into the molecular interaction. Chemical modification studies confirm the requirement for lysine residues in the interaction of fVIII with LRP1. Examination of the ionic strength dependence of the interaction of fVIII with LRP1 resulted in a Debye-Hückel plot with a slope of 1.8 ± 0.5, suggesting the involvement of two critical charged residues in the interaction of fVIII with LRP1. Kinetic studies utilizing surface plasmon resonance techniques reveal that the high affinity of fVIII for LRP1 results from avidity effects mediated by the interactions of two sites in fVIII with complementary sites on LRP1 to form a bivalent fVIII·LRP1 complex. Furthermore, although fVIII bound avidly to soluble forms of clusters II and IV from LRP1, only soluble cluster IV competed with the binding of fVIII to full-length LRP1, revealing that cluster IV represents the major fVIII binding site in LRP1.
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Affiliation(s)
- Patricia A Young
- From the Center for Vascular and Inflammatory Disease and the Departments of Surgery and Physiology, University of Maryland School of Medicine, Baltimore, Maryland 21201
| | - Mary Migliorini
- From the Center for Vascular and Inflammatory Disease and the Departments of Surgery and Physiology, University of Maryland School of Medicine, Baltimore, Maryland 21201
| | - Dudley K Strickland
- From the Center for Vascular and Inflammatory Disease and the Departments of Surgery and Physiology, University of Maryland School of Medicine, Baltimore, Maryland 21201
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Tabriznia-Tabrizi S, Gholampour M, Mansouritorghabeh H. A close insight to factor VIII inhibitor in the congenital hemophilia A. Expert Rev Hematol 2016; 9:903-13. [PMID: 27367203 DOI: 10.1080/17474086.2016.1208554] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
INTRODUCTION Hemophilia A (HA) has an X-linked pattern of inheritance and is the most common of the hemorrhagic disorders. HA is caused by a decreased or deficiency of the functional clotting factor VIII (FVIII) and effects 1 in 5000-10,000 male births. The common treatment for hemophilia is replacement therapy by plasma-derived or recombinant FVIII. Approximately 20-30% of people with a severe type of HA develop an inhibitor and this phenomenon is the main challenge in the management of these patients. Genetic factors and environmental determinants contribute to inhibitor development. Here, the roles of various genetic and environmental factors such as the type of FVIII concentrate used, the number of exposure days, and peak treatment time will be discussed in detail. It seems this information is helpful for hematologists. AREAS COVERED A literature review was done in January 2016 on PubMed and Scopus using the following keywords:' h(a)emophilia A & factor VIII inhibitor', 'h(a)emophilia A & factor VIII alloantibody', 'h(a)emophilia A & inhibitor'. There was no time limitation; however, there was an English language limitation placed on the articles selected. Expert commentary: Influential genetic and environmental factors in developing inhibitors have been discussed. Most of the risk factors are related to previously untreated patients with hemophili.
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Affiliation(s)
| | - Marzie Gholampour
- a Haematology , Mashhad University of Medical sciences (MUMS) , Mashhad , Iran
| | - Hassan Mansouritorghabeh
- b Allergy Research Center, Ghaem hospital, School of Medicine , Mashhad University of Medical Sciences , Mashhad , Iran
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A subset of high-titer anti-factor VIII A2 domain antibodies is responsive to treatment with factor VIII. Blood 2016; 127:2028-34. [PMID: 26825708 DOI: 10.1182/blood-2015-09-670034] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2015] [Accepted: 01/20/2016] [Indexed: 11/20/2022] Open
Abstract
The primary B-cell epitopes of factor VIII (fVIII) are in the A2 and C2 domains. Within the C2 domain, antibody epitope and kinetics are more important than inhibitor titer in predicting pathogenicity in a murine bleeding model. To investigate this within the A2 domain, the pathogenicity of a diverse panel of antihuman fVIII A2 domain monoclonal antibodies (MAbs) was tested in the murine model. MAbs were injected into hemophilia A mice, followed by injection of human B domain-deleted fVIII. Blood loss after a 4-mm tail snip was measured. The following anti-A2 MAbs were tested: high-titer type 1 inhibitors 4A4, 2-76, and 1D4; 2-54, a high-titer type 2 inhibitor; B94, a type 2 inhibitor; and noninhibitory MAbs GMA-012, 4C7, and B25. All high-titer type 1 MAbs produced blood loss that was significantly greater than control mice, whereas all non-inhibitory MAbs produced blood loss that was similar to control. The type 2 MAbs were not pathogenic despite 2-54 having an inhibitor titer of 34 000 BU/mg immunoglobulin G. In addition, a patient with a high-titer type 2 anti-A2 inhibitor who is responsive to fVIII is reported. The discrepancy between inhibitor titer and bleeding phenotype combined with similar findings in the C2 domain stress the importance of inhibitor properties not detected in the standard Bethesda assay in predicting response to fVIII therapy.
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Pratt KP. Engineering less immunogenic and antigenic FVIII proteins. Cell Immunol 2015; 301:12-7. [PMID: 26566286 DOI: 10.1016/j.cellimm.2015.10.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Accepted: 10/22/2015] [Indexed: 01/03/2023]
Abstract
The development of neutralizing antibodies against blood coagulation factor VIII (FVIII), referred to clinically as "inhibitors", is the most challenging and deleterious adverse event to occur following intravenous infusions of FVIII to treat hemophilia A. Inhibitors occlude FVIII surfaces that must bind to activated phospholipid membranes, the serine proteinase factor IXa, and other components of the 'intrinsic tenase complex' in order to carry out its important role in accelerating blood coagulation. Inhibitors develop in up to one of every three patients, yet remarkably, a substantial majority of severe hemophilia A patients, who circulate no detectable FVIII antigen or activity, acquire immune tolerance to FVIII during initial infusions or else after intensive FVIII therapy to overcome their inhibitor. The design of less immunogenic FVIII proteins through identification and modification ("de-immunization") of immunodominant T-cell epitopes is an important goal. For patients who develop persistent inhibitors, modification of B-cell epitopes through substitution of surface-exposed amino acid side chains and/or attachment of bulky moieties to interfere with FVIII attachment to antibodies and memory B cells is a promising approach. Both experimental and computational methods are being employed to achieve these goals. Future therapies for hemophilia A, as well as other monogenic deficiency diseases, are likely to involve administration of less immunogenic proteins in conjunction with other novel immunotherapies to promote a regulatory cellular environment promoting durable immune tolerance.
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Affiliation(s)
- Kathleen P Pratt
- Department of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD, United States.
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Zakas P, Vanijcharoenkarn K, Markovitz R, Meeks S, Doering C. Expanding the ortholog approach for hemophilia treatment complicated by factor VIII inhibitors. J Thromb Haemost 2015; 13:72-81. [PMID: 25315236 PMCID: PMC4295011 DOI: 10.1111/jth.12755] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Accepted: 09/26/2014] [Indexed: 01/18/2023]
Abstract
BACKGROUND The formation of neutralizing antibodies (inhibitors) directed against human coagulation factor VIII (hFVIII) is a life-threatening pathogenic response that occurs in 20-30% of severe congenital hemophilia A patients and 0.00015% of the remaining population (i.e. acquired hemophilia A). Interspecies amino acid sequence disparity among FVIII orthologs represents a promising strategy to mask FVIII from existing inhibitors while retaining procoagulant function. Evidence for the effectiveness of this approach exists in clinical data obtained for porcine FVIII (pFVIII) products, which have demonstrated efficacy in the setting of congenital and acquired hemophilia. OBJECTIVES In the current study, recombinant (r) ovine FVIII (oFVIII) was evaluated for antigenicity and procoagulant activity in the context of human patient-derived and murine model-generated FVIII inhibitors. METHODS The antigenicity of roFVIII was assessed using (i) inhibitor patient plasma samples, (ii) murine anti-FVIII MAbs, (iii) immunized murine hemophilia A plasmas and (iv) an in vivo model of acquired hemophilia A. RESULTS Overall, roFVIII demonstrated reduced reactivity to, and inhibition by, anti-hFVIII immunoglobulin in patient plasmas. Additionally, several hFVIII epitopes were predicted and empirically shown not to exist within roFVIII. In a murine hemophilia A model designed to mimic clinical inhibitor formation, it was demonstrated that inhibitor titers to roFVIII were significantly reduced when compared with the orthologous immunogens, rhFVIII or rpFVIII. Furthermore, in a murine model of acquired hemophilia A, roFVIII administration conferred protection from bleeding following tail transection. CONCLUSION These data support the investigation of FVIII orthologs as treatment modalities in both the congenital and acquired FVIII inhibitor settings.
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Affiliation(s)
- P.M. Zakas
- Graduate Program in Molecular and Systems Pharmacology, Laney Graduate School, Emory University, Atlanta, GA
| | | | - R.C. Markovitz
- Graduate Program in Immunology and Molecular Pathogenesis, Laney Graduate School, Emory University, Atlanta, GA
| | - S.L. Meeks
- Aflac Cancer and Blood Disorders Center, Emory University/Children’s Healthcare of Atlanta, Atlanta, GA
| | - C.B. Doering
- Aflac Cancer and Blood Disorders Center, Emory University/Children’s Healthcare of Atlanta, Atlanta, GA
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Lebreton A, Simon N, Moreau V, Demolombe V, Cayzac C, Nguyen C, Schved JF, Granier C, Lavigne-Lissalde G. Computer-predicted peptides that mimic discontinuous epitopes on the A2 domain of factor VIII. Haemophilia 2014; 21:e193-e201. [PMID: 25422151 DOI: 10.1111/hae.12575] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/28/2014] [Indexed: 12/21/2022]
Abstract
Development of antibodies (Abs) against factor VIII (FVIII) is a severe complication of haemophilia A treatment. Recent publications suggest that domain specificity of anti-FVIII antibodies, particularly during immune tolerance induction (ITI), might be related to the outcome of the treatment. Obtaining suitable tools for a fine mapping of discontinuous epitopes could thus be helpful. The aim of this study was to map discontinuous epitopes on FVIII A2 domain using a new epitope prediction functionality of the PEPOP bioinformatics tool and a peptide inhibition assay based on the Luminex technology. We predicted, selected and synthesized 40 peptides mimicking discontinuous epitopes on the A2 domain of FVIII. A new inhibition assays using Luminex technology was performed to identify peptides able to inhibit the binding of anti-A2 Abs to A2 domain. We identified two peptides (IFKKLYHVWTKEVG and LYSRRLPKGVKHFD) able to block the binding of anti-A2 allo-antibodies to this domain. The three-dimensional representation of these two peptides on the A2 domain revealed that they are localized on a limited region of A2. We also confirmed that residues 484-508 of the A2 domain define an antigenic site. We suggest that dissection of the antibody response during ITI using synthetic peptide epitopes could provide important information for the management of patients with inhibitors.
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Affiliation(s)
- A Lebreton
- UMR 3145 SysDiag CNRS/Bio-Rad, Parc Euromédecine, Montpellier, France; CHU Clermont-Ferrand, Service d'Hématologie Biologique, Clermont-Ferrand, France
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Nguyen PCT, Lewis KB, Ettinger RA, Schuman JT, Lin JC, Healey JF, Meeks SL, Lollar P, Pratt KP. High-resolution mapping of epitopes on the C2 domain of factor VIII by analysis of point mutants using surface plasmon resonance. Blood 2014; 123:2732-9. [PMID: 24591205 PMCID: PMC3999758 DOI: 10.1182/blood-2013-09-527275] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Accepted: 02/09/2014] [Indexed: 11/20/2022] Open
Abstract
Neutralizing anti-factor VIII (FVIII) antibodies that develop in patients with hemophilia A and in murine hemophilia A models, clinically termed "inhibitors," bind to several distinct surfaces on the FVIII-C2 domain. To map these epitopes at high resolution, 60 recombinant FVIII-C2 proteins were generated, each having a single surface-exposed residue mutated to alanine or a conservative substitution. The binding kinetics of these muteins to 11 monoclonal, inhibitory anti-FVIII-C2 antibodies were evaluated by surface plasmon resonance and the results compared with those obtained for wild-type FVIII-C2. Clusters of residues with significantly altered binding kinetics identified "functional" B-cell epitopes, defined as those residues contributing appreciable antigen-antibody avidity. These antibodies were previously shown to neutralize FVIII activity by interfering with proteolytic activation of FVIII by thrombin or factor Xa, or with its binding to phospholipid surfaces, von Willebrand factor, or other components of the intrinsic tenase complex. Fine mapping of epitopes by surface plasmon resonance also indicated surfaces through which FVIII interacts with proteins and phospholipids as it participates in coagulation. Mutations that significantly altered the dissociation times/half-lives identified functionally important interactions within antigen-antibody interfaces and suggested specific sequence modifications to generate novel, less antigenic FVIII proteins with possible therapeutic potential for treatment of inhibitor patients.
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Zimmermann MA, Oldenburg J, Müller CR, Rost S. Expression studies of mutant factor VIII alleles with premature termination codons with regard to inhibitor formation. Haemophilia 2014; 20:e215-21. [DOI: 10.1111/hae.12388] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/27/2014] [Indexed: 01/21/2023]
Affiliation(s)
- M. A. Zimmermann
- Department of Human Genetics; University of Würzburg; Würzburg Germany
| | - J. Oldenburg
- Institute of Experimental Haematology and Transfusion Medicine; University of Bonn; Bonn Germany
| | - C. R. Müller
- Department of Human Genetics; University of Würzburg; Würzburg Germany
| | - S. Rost
- Department of Human Genetics; University of Würzburg; Würzburg Germany
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Abstract
Approximately 30% of patients with severe hemophilia A develop inhibitory anti-factor VIII (fVIII) antibodies (Abs). We characterized 29 anti-human A2 monoclonal Abs (mAbs) produced in a murine hemophilia A model. A basis set of nonoverlapping mAbs was defined by competition enzyme-linked immunosorbent assay, producing 5 major groups. The overlapping epitopes covered nearly the entire A2 surface when mapped by homolog-scanning mutagenesis. Most group A mAbs recognized a previously described epitope bounded by Arg484-Ile508 in the N-terminal A2 subdomain, resulting in binding to activated fVIII and noncompetitive inhibition of the intrinsic fXase complex. Group B and C mAbs displayed little or no inhibitory activity. Group D and E mAbs recognized epitopes in the C-terminal A2 subdomain. A subset of group D mAbs inhibited the activation of fVIII by interfering with thrombin-catalyzed cleavage at Arg372 at the A1-A2 domain junction. Other group D mAbs displayed indeterminate or no inhibitory activity despite inhibiting cleavage at Arg740 at the A2-B domain junction. Group E mAbs inhibited fVIII light-chain cleavage at Arg1689. Inhibition of cleavages at Arg372 and Arg1689 represent novel mechanisms of inhibitor function and, along with the extensive epitope spectrum identified in this study, reveal hitherto unrecognized complexity in the immune response to fVIII.
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Doshi BS, Gangadharan B, Doering CB, Meeks SL. Potentiation of thrombin generation in hemophilia A plasma by coagulation factor VIII and characterization of antibody-specific inhibition. PLoS One 2012; 7:e48172. [PMID: 23144741 PMCID: PMC3483154 DOI: 10.1371/journal.pone.0048172] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2012] [Accepted: 09/20/2012] [Indexed: 11/18/2022] Open
Abstract
Development of inhibitory antibodies to coagulation factor VIII (fVIII) is the primary obstacle to the treatment of hemophilia A in the developed world. This adverse reaction occurs in 20-30% of persons with severe hemophilia A treated with fVIII-replacement products and is characterized by the development of a humoral and neutralizing immune response to fVIII. Patients with inhibitory anti-fVIII antibodies are treated with bypassing agents including recombinant factor VIIa (rfVIIa). However, some patients display poor hemostatic response to bypass therapy and improved treatment options are needed. Recently, we demonstrated that fVIII inhibitors display widely variable kinetics of inhibition that correlate with their respective target epitopes. Thus, it was hypothesized that for antibodies that display slow rates of inhibition, supplementation of rfVIIa with fVIII would result in improved thrombin generation and be predictive of clinical responses to this novel treatment regimen. In order to test this hypothesis, 10 murine monoclonal antibodies (MAbs) with non-overlapping epitopes spanning fVIII, differential inhibition titers, and inhibition kinetics were studied using a thrombin generation assay. Of the 3 MAbs with high inhibitory titers, only the one with fast and complete (classically defined as "type I") kinetics displayed significant inhibition of thrombin generation with no improvement upon supplementation of rfVIIa with fVIII. The other two MAbs that displayed incomplete (classically defined as "type II") inhibition did not suppress the potentiation of thrombin generation by fVIII. All antibodies that did not completely inhibit fVIII activity demonstrated potentiation of thrombin generation by the addition of fVIII as compared to rfVIIa alone. In conclusion, fVIII alone or in combination with rfVIIa corrects the thrombin generation defect produced by the majority of anti-fVIII MAbs better than single agent rfVIIa. Therefore, combined fVIII/rfVIIa therapy may provide better hemostatic control than current therapy in some patients with anti-fVIII inhibitors.
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Affiliation(s)
- Bhavya S. Doshi
- Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Bagirath Gangadharan
- Aflac Cancer Center and Blood Disorders Service, Children’s Healthcare of Atlanta and Emory University, Atlanta, Georgia, United States of America
| | - Christopher B. Doering
- Aflac Cancer Center and Blood Disorders Service, Children’s Healthcare of Atlanta and Emory University, Atlanta, Georgia, United States of America
| | - Shannon L. Meeks
- Aflac Cancer Center and Blood Disorders Service, Children’s Healthcare of Atlanta and Emory University, Atlanta, Georgia, United States of America
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21
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A major determinant of the immunogenicity of factor VIII in a murine model is independent of its procoagulant function. Blood 2012; 120:2512-20. [PMID: 22855607 DOI: 10.1182/blood-2012-02-412361] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
A main complication of treatment of patients with hemophilia A is the development of anti-factor VIII (fVIII) antibodies. The immunogenicity of fVIII potentially is a function of its procoagulant activity, which may result in danger signals that drive the immune response. Alternatively, intrinsic structural elements in fVIII may be particularly immunogenic. Finally, VWF, the carrier protein for fVIII in plasma, may play a role in immune recognition. We compared the immunogenicity of wild-type (wt) B domain-deleted fVIII and 2 inactive fVIII molecules, R372A/R1689A fVIII and V634M fVIII in fVIII(-/-) and fVIII(-/-)/VWF(-/-) mice. R372A/R1689A fVIII lacks proteolytic recognition sites and is not released from VWF. In contrast, V634M fVIII undergoes proteolytic cleavage and dissociation from VWF. No significant difference was observed in the immunogenicity of wt fVIII and V634M fVIII. R372A/R1689A fVIII was slightly less immunogenic in a subset of immunization regimens tested. High doses of wt fVIII were required to produce an immune response in fVIII(-/-)/VWF(-/-) mice. Our results indicate that a main component of the immune response to fVIII is independent of its procoagulant function, is both positively and negatively affected by its association with VWF, and may involve intrinsic elements of fVIII structure.
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Peng A, Kosloski MP, Nakamura G, Ding H, Balu-Iyer SV. PEGylation of a factor VIII-phosphatidylinositol complex: pharmacokinetics and immunogenicity in hemophilia A mice. AAPS JOURNAL 2011; 14:35-42. [PMID: 22173945 DOI: 10.1208/s12248-011-9309-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Accepted: 11/02/2011] [Indexed: 11/30/2022]
Abstract
Hemophilia A is an X-linked bleeding disorder caused by the deficiency of factor VIII (FVIII). Exogenous FVIII is administered therapeutically, and due to a short half-life, frequent infusions are often required. Fifteen to thirty-five percent of severe hemophilia A patients develop inhibitory antibodies toward FVIII that complicate clinical management of the disease. Previously, we used phosphatidylinositol (PI) containing lipidic nanoparticles to improve the therapeutic efficacy of recombinant FVIII by reducing immunogenicity and prolonging the circulating half-life. The objective of this study is to investigate further improvements in the FVIII-PI formulation resulting from the addition of polyethylene glycol (PEG) to the particle. PEGylation was achieved by passive transfer of PEG conjugated lipid into the FVIII-PI complex. PEGylated FVIII-PI (FVIII-PI/PEG) was generated with high association efficiency. Reduced activity in vitro and improved retention of activity in the presence of antibodies suggested strong shielding of FVIII by the particle; thus, in vivo studies were conducted in hemophilia A mice. Following intravenous administration, the apparent terminal half-life was improved versus both free FVIII and FVIII-PI, but exposure determined by area under the curve was reduced. The formation of inhibitory antibodies after subcutaneous immunization with FVIII-PI/PEG was lower than free FVIII but resulted in a significant increase in inhibitors following intravenous administration. Passive transfer of PEG onto the FVIII-PI complex does not provide any therapeutic benefit.
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Affiliation(s)
- Aaron Peng
- Department of Pharmaceutical Sciences, University at Buffalo, State University of New York, Amherst, 14260, USA
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Griffiths AE, Wang W, Hagen FK, Fay PJ. Use of affinity-directed liquid chromatography-mass spectrometry to map the epitopes of a factor VIII inhibitor antibody fraction. J Thromb Haemost 2011; 9:1534-40. [PMID: 21668738 PMCID: PMC3154976 DOI: 10.1111/j.1538-7836.2011.04397.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND Neutralizing factor (F) VIII antibodies develop in approximately 30% of individuals with hemophilia A and show specificity to multiple sites in the FVIII protein. METHODS Reactive epitopes to an immobilized IgG fraction prepared from a high-titer, FVIII inhibitor plasma were determined after immuno-precipitation (IP) of tryptic and chymotryptic peptides derived from digests of the A1 and A2 subunits of FVIIIa and FVIII light chain. Peptides were detected and identified using highly sensitive liquid chromatography-mass spectrometry (LC-MS). RESULTS Coverage maps of the A1 subunit, A2 subunit and light chain represented 79%, 69% and 90%, respectively, of the protein sequences. Dot blots indicated that the inhibitor IgG reacted with epitopes contained within each subunit of FVIIIa. IP coupled with LC-MS identified 19 peptides representing epitopes from all FVIII A and C domains. The majority of peptides (10) were derived from the A2 domain. Three peptides mapped to the C2 domain, while two mapped to the A1 and A3 domains, and single peptides mapped to the a1 segment and C1 domain. Epitopes were typically defined by peptide sequences of < 12 residues. CONCLUSIONS IP coupled with LC-MS identified extensive antibody reactivity at high resolution over the entire functional FVIII molecule and yielded sequence lengths of < 15 residues. A number of the peptides identified mapped to known sequences involved in functionally important protein-protein and protein-membrane interactions.
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Affiliation(s)
- Amy E. Griffiths
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine, Rochester, NY 14642 USA
| | - Wensheng Wang
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine, Rochester, NY 14642 USA
| | - Fred K. Hagen
- Proteomics Center, University of Rochester School of Medicine, Rochester, NY 14642 USA
| | - Philip J. Fay
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine, Rochester, NY 14642 USA
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VAN HELDEN PMW, KAIJEN PHP, MAUSER-BUNSCHOTEN EP, FISCHER K, VAN DEN BERG HM, VOORBERG J. Domain specificity of factor VIII inhibitors during immune tolerance induction in patients with haemophilia A. Haemophilia 2010; 16:892-901. [DOI: 10.1111/j.1365-2516.2010.02272.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Gershom ES, Sutherland MR, Lollar P, Pryzdial ELG. Involvement of the contact phase and intrinsic pathway in herpes simplex virus-initiated plasma coagulation. J Thromb Haemost 2010; 8:1037-43. [PMID: 20128864 DOI: 10.1111/j.1538-7836.2010.03789.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
SUMMARY BACKGROUND A hemostatic response to vascular injury is initiated by the extrinsic pathway of coagulation and amplified by the intrinsic pathway. We previously reported that purified herpes simplex virus type-1 (HSV1) has constitutive extrinsic pathway tissue factor (TF) and anionic phospholipid on its surface derived from the host cell, and can consequently bypass strict cellular control of coagulation. OBJECTIVE The current work addresses the hypothesis that HSV1-induced plasma coagulation also involves intrinsic pathway, factor VIII (FVIII), and upstream contact activation pathway, factor XII (FXII). RESULTS HSV1-initiated clotting was accelerated when purified FVIII was added to FVIII-deficient plasma and in normal plasma attenuated by an inhibitory anti-FVIII antibody (Ab). High HSV1 concentrations predictably reduced the effect of FVIII due to the availability of excess viral TF. To further define TF-independent clotting mechanisms initiated by HSV1, the extrinsic pathway was disabled using factor VII-deficient plasma. The intrinsic pathway is triggered by activation of FXII associated with surface-bound kallikrein, which subsequently activates factor XI. Here we found that an inhibitor of activated FXII, corn trypsin inhibitor, and anti-FXII, anti-kallikrein and anti-FXI Abs inhibited HSV1-initiated clotting. HSV1-enhanced activation of purified FXII was confirmed by Western blot, but required prekallikrein. CONCLUSION The current work shows that HSV1 can trigger and amplify coagulation through the contact phase and intrinsic pathway, and suggests an additional mechanism that may contribute to vascular pathology.
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Affiliation(s)
- E S Gershom
- Department of Pathology and Laboratory Medicine, Centre for Blood Research, University of British Columbia, British Columbia, Canada
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Rational design of a fully active, long-acting PEGylated factor VIII for hemophilia A treatment. Blood 2010; 116:270-9. [PMID: 20194895 DOI: 10.1182/blood-2009-11-254755] [Citation(s) in RCA: 176] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
A long-acting factor VIII (FVIII) as a replacement therapy for hemophilia A would significantly improve treatment options for patients with hemophilia A. To develop a FVIII with an extended circulating half-life, but without a reduction in activity, we have engineered 23 FVIII variants with introduced surface-exposed cysteines to which a polyethylene glycol (PEG) polymer was specifically conjugated. Screening of variant expression level, PEGylation yield, and functional assay identified several conjugates retaining full in vitro coagulation activity and von Willebrand factor (VWF) binding.PEGylated FVIII variants exhibited improved pharmacokinetics in hemophilic mice and rabbits. In addition, pharmacokinetic studies in VWF knockout mice indicated that larger molecular weight PEG may substitute for VWF in protecting PEGylated FVIII from clearance in vivo. In bleeding models of hemophilic mice, PEGylated FVIII not only exhibited prolonged efficacy that is consistent with the improved pharmacokinetics but also showed efficacy in stopping acute bleeds comparable with that of unmodified rFVIII. In summary site-specifically PEGylated FVIII has the potential to be a long-acting prophylactic treatment while being fully efficacious for on-demand treatment for patients with hemophilia A.
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Characteristics, mechanisms of action, and epitope mapping of anti-factor VIII antibodies. Clin Rev Allergy Immunol 2009; 37:67-79. [PMID: 19172415 DOI: 10.1007/s12016-009-8119-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
The development of anti-factor VIII (FVIII) antibodies (Abs), also called inhibitors, is currently one of the most serious complications arising during the treatment of hemophilia A patients. Improved prevention and eradication of these Abs remain a challenge both for clinicians and scientists. Numerous studies in the literature have reported on their epitope specificity, on their mechanism of FVIII inactivation, as well as on the methods used for their detection. In this review, we summarize the current knowledge on the nature (isotypes, kinetic properties), epitope properties, and mechanisms of action of anti-FVIII Abs. Furthermore, we present methods for detection and epitope characterization of anti-FVIII Abs with emphasis on the Luminex technique susceptible to facilitate the monitoring of changes in the epitope specificity of these Abs.
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Healey JF, Parker ET, Barrow RT, Langley TJ, Church WR, Lollar P. The comparative immunogenicity of human and porcine factor VIII in haemophilia A mice. Thromb Haemost 2009; 102:35-41. [PMID: 19572065 DOI: 10.1160/th08-12-0818] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Inhibitory antibodies to factor VIII (FVIII inhibitors) are the most significant complication in the management of haemophilia A. The immunogenicity of FVIII may be driven in part by structural determinants within the FVIII molecule itself. Regions of nonidentity between human and porcine FVIII possibly could drive differential immune responses. The goal of this study was to compare the overall antibody response and levels of antibodies to the individual FVIII domains in naïve haemophilia A mice immunised with human or porcine FVIII. Haemophilia A mice were immunised with human or porcine FVIII using a protocol that mimics human clinical use. Inhibitor and total anti-FVIII antibody titers were measured and the domain-specificity of antibodies from 1,759 anti-FVIII hybridomas was determined. The overall immunogenicity of human and porcine FVIII was similar but significant differences in domain recognition were discovered. Anti-A2 and anti-C2 antibodies constituted the majority of inhibitors in both the human and porcine FVIII groups, similar to inhibitors that develop in humans. The proportions of anti-A2 or anti-C2 antibodies were not significantly different between the two groups. However, the specific inhibitory activity of anti-A2 antibodies was higher in the human FVIII group. Additionally, proportion of anti-C1 antibodies was significantly higher in the human FVIII group. In contrast, anti-A3 antibodies were more common in the porcine FVIII group. The differential immune response to human and porcine FVIII suggests that it may be possible to reduce the immunogenicity of FVIII by mutagenesis of the A2, A3 and C1 domains.
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Affiliation(s)
- John F Healey
- Aflac Cancer Center and Blood Disorders Service, Department of Pediatrics, Children's Healthcare of Atlanta and Emory University, Atlanta, Georgia, USA
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Pratt KP, Thompson AR. B-Cell and T-Cell Epitopes in Anti-factor VIII Immune Responses. Clin Rev Allergy Immunol 2009; 37:80-95. [DOI: 10.1007/s12016-009-8120-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Ramani K, Purohit V, Miclea R, Gaitonde P, Straubinger RM, Balu-Iyer SV. Passive transfer of polyethylene glycol to liposomal-recombinant human FVIII enhances its efficacy in a murine model for hemophilia A. J Pharm Sci 2008; 97:3753-64. [PMID: 18300296 DOI: 10.1002/jps.21266] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The replacement therapy using recombinant human FVIII (rFVIII) is the first line of therapy for hemophilia A. Approximately 15-30% of the patients develop inhibitory antibodies. Recently, we reported that liposomes composed of phosphatidylserine (PS) could reduce the immunogenicity of rFVIII. However, PS containing liposomal-rFVIII is likely to reduce the systemic exposure and efficacy of FVIII due to rapid uptake of the PS containing liposomes by the reticuloendothelial system (RES). Here, we investigated whether phosphatidylserine (PS) liposomes containing Polyethylene glycol (PEG) (PEGylated), could reduce the immunogenicity of rFVIII and reverse the reduction in systemic exposure of rFVIII. Animals given PEGylated liposomal-rFVIII had lower total and inhibitory anti-rFVIII antibody titers, compared to animals treated with rFVIII alone. The mean stimulation index of CD4+ T-cells from animals given PEGylated liposomal-rFVIII also was lower than for animals that were given rFVIII alone. Pharmacokinetic studies following intravenous dosing indicated that the systemic exposure (area under the activity curve, AUAC(0-24h)) of PEGylated liposomal-rFVIII was approximately 59 IU/mL x h and significantly higher than that of non-PEGylated liposomal-rFVIII (AUAC(0-24h) approximately 36 IU/mL x h). Based on these studies, we speculate that PEGylated PS-containing liposomal rFVIII may improve efficacy of rFVIII.
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Affiliation(s)
- Karthik Ramani
- Department of Pharmaceutical Sciences, 521 Hochstetter Hall, University at Buffalo, State University of New York, Amherst, New York 14260, USA
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Interaction of coagulation factor VIII with members of the low-density lipoprotein receptor family follows common mechanism and involves consensus residues within the A2 binding site 484–509. Blood Coagul Fibrinolysis 2008; 19:543-55. [DOI: 10.1097/mbc.0b013e3283068859] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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The binding sites for the very low density lipoprotein receptor and low-density lipoprotein receptor-related protein are shared within coagulation factor VIII. Blood Coagul Fibrinolysis 2008; 19:166-77. [PMID: 18277139 DOI: 10.1097/mbc.0b013e3282f5457b] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Coagulation factor VIII (FVIII) is a ligand for two members of the low-density lipoprotein receptor family, low-density lipoprotein receptor-related protein (LRP) and low-density lipoprotein receptor, which cooperate in regulating clearance of FVIII from the circulation. This study was aimed to explore the mechanism of interaction of FVIII with very low density lipoprotein receptor (VLDLR), another member of the family, and map receptor-binding sites. Binding of plasma-derived FVIII and its fragments to recombinant soluble ectodomain of VLDLR (sVLDLR) was studied in solid-phase and surface plasmon resonance assays. Full-length FVIII and its light chain bound to sVLDLR with similar affinities (KD = 114 +/- 14 and 95 +/- 11 nmol/l, respectively); in contrast, exposure of high-affinity VLDLR-binding site within the heavy chain (KD = 30 +/- 2 nmol/l) required proteolytic cleavage by thrombin. The VLDLR-binding sites within heavy and light chains were mapped to the A2 domain residues 484-509 and the A3-C1 fragment, based on the inhibitory effects of anti-A2 monoclonal antibody 413 and anti-A3-C1 antibody fragment scFv KM33, respectively, previously shown to inhibit FVIII/LRP interaction. Soluble ligand-binding fragment of VLDLR inhibited activation of factor X by the intrinsic Xase in purified system. In cell culture, a higher Xase activity was associated with wild-type human embryonic kidney cells compared with transfected cells that express VLDLR on the cell surface. We conclude that the binding sites for VLDLR and LRP within FVIII overlap and the A2 site becomes exposed upon physiological activation of FVIII. A functional role of FVIII/VLDLR interaction may be related to regulation of intrinsic Xase activity.
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Planque S, Escobar MA, Smith KC, Taguchi H, Nishiyama Y, Donnachie E, Pratt KP, Paul S. Covalent inactivation of factor VIII antibodies from hemophilia A patients by an electrophilic FVIII Analog. J Biol Chem 2008; 283:11876-86. [PMID: 18337255 PMCID: PMC2335366 DOI: 10.1074/jbc.m800589200] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2008] [Revised: 03/05/2008] [Indexed: 11/06/2022] Open
Abstract
The antigen-binding sites of antibodies (Abs) can express enzyme-like nucleophiles that react covalently with electrophilic compounds. We examined the irreversible and specific inactivation of antibodies (Abs) to Factor VIII (FVIII) responsible for failure of FVIII replacement therapy in hemophilia A (HA) patients. Electrophilic analogs of FVIII (E-FVIII) and its C2 domain (E-C2) were prepared by placing the strongly electrophilic phosphonate groups at surface-exposed Lys side chains of diverse antigenic epitopes. IgG Abs to FVIII from HA patients formed stable immune complexes with E-FVIII and E-C2 that were refractory to dissociation by SDS treatment and boiling, procedures that dissociate noncovalent Ab-antigen complexes. The rate-limiting step in the reaction was formation of the initial noncovalent complexes. Conversion of the initial complexes to the irreversible state occurred rapidly. The antigenic epitopes of E-FVIII were largely intact, and most of the Abs were consumed covalently. E-FVIII expressed poor FVIII cofactor activity in clotting factor assays. Nonspecific interference by E-FVIII in clotting factor function was not evident. Treatment with E-FVIII, and to a lesser extent E-C2, irreversibly relieved the FVIII inhibitory effect of HA IgG in clotting factor assays. Small FVIII peptides did not display useful reactivity, highlighting the diverse epitope specificities of the Abs and the conformational character of FVIII epitopes. E-FVIII is a prototype reagent able to attain irreversible and specific inactivation of pathogenic Abs.
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Affiliation(s)
- Stephanie Planque
- Chemical Immunology Research Center, Department of Pathology, University of Texas-Houston Medical School, Houston, Texas 77030, USA
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Nogami K, Nishiya K, Saenko EL, Takeyama M, Tanaka I, Yoshioka A, Shima M. Identification of a plasmin-interactive site within the A2 domain of the factor VIII heavy chain. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2008; 1784:753-63. [DOI: 10.1016/j.bbapap.2008.01.019] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2007] [Revised: 01/30/2008] [Accepted: 01/31/2008] [Indexed: 11/28/2022]
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35
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Nogami K, Saenko EL, Takeyama M, Giddings JC, Yoshioka A, Shima M. Identification of a thrombin-interactive site within the FVIII A2 domain that is responsible for the cleavage at Arg372. Br J Haematol 2007; 140:433-43. [PMID: 18081893 DOI: 10.1111/j.1365-2141.2007.06935.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
FVIII is activated by cleavage at Arg(372), Arg(740), and Arg(1689) by thrombin. This study showed that an anti-A2 monoclonal antibody, with a specific epitope for residues 484-509, and anti-FVIII inhibitor alloantibodies with similar A2 epitopes, inhibited thrombin-catalyzed FVIII activation. Sodium dodecyl sulphate polyacrylamide gel electrophoresis analysis showed that cleavage at Arg(372) but not at Arg(740) occurred at approximately fourfold decreased rate in the presence of anti-A2 antibody. Peptide 484-509 also inhibited co-factor activation, consistent with inhibition of cleavage at Arg(372). Direct binding studies using active-site modified thrombin showed that a 484-509 peptide as well as the anti-A2 antibodies blocked the A2-thrombin binding. Furthermore, covalent cross-linking was observed between the 484-509 peptide and thrombin following reaction with 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide. Mutant A2 molecules in which the clustered basic residues in this sequence were converted to alanine were used to assess the binding reactions in a surface plasmon resonance-based assay. Mutants R484A, R489A, R490A, H497A and K499A possessed two to fivefold lower affinity than wild-type A2. These findings demonstrate that clustered basic residues within the 484-509 region of the A2 domain play a part of key role in thrombin-binding, which is responsible for thrombin-catalyzed FVIII activation by cleavage at Arg(372).
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Affiliation(s)
- Keiji Nogami
- Department of Paediatrics, Nara Medical University, Kashihara, Nara, Japan.
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James EA, Kwok WW, Ettinger RA, Thompson AR, Pratt KP. T-cell responses over time in a mild hemophilia A inhibitor subject: epitope identification and transient immunogenicity of the corresponding self-peptide. J Thromb Haemost 2007; 5:2399-407. [PMID: 18034765 DOI: 10.1111/j.1538-7836.2007.02762.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND Antibodies that neutralize factor (F) VIII activity, clinically referred to as 'inhibitors', complicate the treatment of hemophilia A patients; current tolerance and bypass strategies are extremely costly and sometimes ineffective. The development of inhibitors requires T-cell help. OBJECTIVES We characterized T-cell responses of a subject with mild hemophilia A with missense genotype A2201P for one year following his initial inhibitor response, with the goals of defining the primary epitope(s) and its (their) MHC Class II restriction. We investigated the possible involvement of regulatory T cells in modulating immune responses. PATIENTS/METHODS The subject developed high-titer FVIII-neutralizing antibodies (250 BU mL(-1)) that declined over time to 8 BU ml(-1). His clotting activity was initially impaired (3%) but returned to baseline (8-10%) within four weeks. MHC Class II tetramers were used to analyze his CD4 T cells, which were stimulated with peptides spanning the C2 domain. Responses of total and CD25-depleted CD4 cells to sequences containing A2201 (native), P2201 (hemophilic), and other predicted T-cell epitopes were evaluated. RESULTS AND CONCLUSIONS An HLA-DRA-DRB1*0101 restricted T-cell epitope containing the wild-type A2201 sequence was identified. Interestingly, peptides containing A2201 were recognized by CD4 T cells at all time points, whereas a P2201 peptide was recognized only near the initial peak response. The responsiveness of CD25-depleted CD4 cells to an A2201 peptide was enhanced 11 and 19 weeks following inhibitor detection, suggesting the possible involvement of CD4+CD25+ regulatory T cells in modulating immune responses. Patient-derived T-cell clones proliferated in response to C2 protein and to peptides containing A2201 but not P2201.
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Affiliation(s)
- E A James
- Benaroya Research Institute, Seattle, WA 98104, USA
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Abstract
Factor VIII (fVIII) is a serum protein in the coagulation cascade that nucleates the assembly of a membrane-bound protease complex on the surface of activated platelets at the site of a vascular injury. Hemophilia A is caused by a variety of mutations in the factor VIII gene and typically requires replacement therapy with purified protein. We have determined the structure of a fully active, recombinant form of factor VIII (r-fVIII), which consists of a heterodimer of peptides, respectively containing the A1-A2 and A3-C1-C2 domains. The structure permits unambiguous modeling of the relative orientations of the 5 domains of r-fVIII. Comparison of the structures of fVIII, fV, and ceruloplasmin indicates that the location of bound metal ions and of glycosylation, both of which are critical for domain stabilization and association, overlap at some positions but have diverged at others.
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Astermark J. Basic aspects of inhibitors to factors VIII and IX and the influence of non-genetic risk factors. Haemophilia 2007; 12 Suppl 6:8-13; discussion 13-4. [PMID: 17123388 DOI: 10.1111/j.1365-2516.2006.01360.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The appearance of polyclonal antibodies inhibiting the function of exogenous factors VIII (FVIII) and IX (FIX) continues to be a major challenge in the treatment of patients with congenital haemophilia. Why these inhibitors develop in 10-20% of patients with haemophilia A, and in 1-5% of patients with haemophilia B, remains largely unexplained. The antibodies, however, are characterized by several features that may have implications for the immune process by which they occur. The FVIII antibodies are mainly directed towards the A2, A3 and C2 domains, thereby interfering with the function of the factor Xase complex, the binding of FVIII to von Willebrand factor, and the binding of FVIII to phospholipid membranes. The FIX epitopes are localized to the NH(2)-terminal gamma-carboxyglutamic acid region and the serine protease domain. Genetic risk factors are known to be of importance in the development of inhibitors, whereas the impact of non-genetic factors is less clear. However, based on studies of related subjects, it is obvious that non-genetic factors are of importance as well. Putative factors currently debated include age at the start of treatment, treatment in association with immune challenges, the type of product, and the mode of administration. Most of the findings reported to date, however, derive from small cohorts that have not been sufficiently well characterized with respect to genetic risk profile. Therefore, additional studies are required to quantify the impact of non-genetic factors on the pathophysiologic process of inhibitor development.
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Affiliation(s)
- J Astermark
- Department for Coagulation Disorders, Malmö University Hospital, Malmö, Sweden.
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Nogami K, Shima M, Giddings JC, Takeyama M, Tanaka I, Yoshioka A. Relationship between the binding sites for von Willebrand factor, phospholipid, and human factor VIII C2 inhibitor alloantibodies within the factor VIII C2 domain. Int J Hematol 2007; 85:317-22. [PMID: 17483075 DOI: 10.1532/ijh97.06192] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Some factor VIII (FVIII) inhibitor alloantibodies block FVIII binding to von Willebrand factor (VWF) and phospholipid (PL) and recognize a C2 domain epitope that overlaps both binding sites. We previously showed that FVIII peptide 2315-2330 neutralized FVIII inhibitors and that Cys2326 and Glu2327 contributed to the maximum neutralizing effect. In the present study, we investigated the relationship between the essential binding sites for VWF, PL, and anti-C2 inhibitors by means of competitive-inhibition assays with overlapping synthetic peptides that span the C terminus of the C2 domain (residues 2288-2332). We identified 2 peptides (residues 2303-2317 and 2315-2330) that specifically blocked FVIII binding to VWF or PL by approximately 80% (50%-inhibitory concentration [IC50], 9.0 microM) and 95% (IC50, 0.12 microM), respectively. To examine in detail the residues responsible for PL binding, we prepared mutants of peptide 2315-2330 in which we sequentially substituted each residue with Gly. Two residues, Ile2317 and Met2321, were shown to be essential for PL binding. Their substitution with Gly reduced the inhibitory effect by >90%. The data suggest that the binding sites for VWF, PL, and anti-C2 inhibitors in the C2 domain are in very close proximity but are not identical.
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Affiliation(s)
- Keiji Nogami
- Department of Pediatrics, Nara Medical University, Kashihara, Nara, Japan
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Parker ET, Lollar P. Contribution of A1 subunit residue Q316 in thrombin-activated factor VIII to A2 subunit dissociation. Biochemistry 2007; 46:9737-42. [PMID: 17676877 PMCID: PMC2525606 DOI: 10.1021/bi700941w] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Blood coagulation factor VIII (fVIII) is activated by thrombin to form an A1/A2/A3-C1-C2 heterotrimer, which functions as a cofactor for factor IXa during intrinsic pathway factor X activation. Human thrombin-activated fVIII (fVIIIa) decays rapidly because of first-order dissociation of the A2 subunit, which may function to regulate the coagulation mechanism. The three fVIII A domains each consist of two cupredoxin-like subdomains. Substitution of the COOH-terminal A1 subdomain of porcine fVIIIa, which decays more slowly than human fVIIIa, reduces the dissociation rate constant for fVIIIa decay. Examination of a human fVIII A1-A2-A3 homology model [Pemberton, S., et al. (1997) Blood 89, 2413-2421) revealed a possible interaction between Q316 in the FG helix of the COOH-terminal A1 subdomain and M539 in the FG helix of the NH2-terminal A2 subdomain, which are sites where human and porcine fVIII differ. Decays of purified recombinant human and porcine fVIIIa and the human fVIIIa mutants Q316H, M539L and Q316H/M539L were compared at 23 and 37 degrees C. The decay rates of the Q316H and Q316H/M539L mutants, but not the M539L mutant, were significantly slower than human fVIIIa. These results indicate that the FG helix of the COOH-terminal A1 cupredoxin-like subdomain of fVIII may be under selective pressure by the requirements of hemostatic balance.
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Affiliation(s)
| | - Pete Lollar
- Address correspondence to: Pete Lollar, Room 426D, Emory Children's Center, 2015 Uppergate Drive, Atlanta, GA 30322. Tel.: 404-727-5569; Fax: 404-727-4859;
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Healey JF, Parker ET, Barrow RT, Langley TJ, Church WR, Lollar P. The humoral response to human factor VIII in hemophilia A mice. J Thromb Haemost 2007; 5:512-9. [PMID: 17181826 DOI: 10.1111/j.1538-7836.2007.02373.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
BACKGROUND Inhibitory antibodies (Abs) to factor VIII (FVIII inhibitors) constitute the most significant complication in the management of hemophilia A. The analysis of FVIII inhibitors is confounded by polyclonality and the size of FVIII. OBJECTIVES The goal of this study was to dissect the polyclonal response to human FVIII in hemophilia A mice undergoing a dosage schedule that mimics human use. METHODS Splenic B-cell hybridomas were obtained following serial i.v. injections of submicrogram doses of FVIII. Results of a novel, anti-FVIII domain-specific enzyme-linked immunosorbent assay were compared to Ab isotype and anti-FVIII inhibitory activity. RESULTS The robust immune response resulted in the production of approximately 300 hybridomas per spleen. We characterized Abs from 506 hybridomas, representing the most comprehensive analysis of a protein antigen to date. Similar to the human response to FVIII, anti-A2 and anti-C2 Abs constituted the majority of inhibitors. A novel epitope was identified in the A2 domain by competition ELISA. Anti-A2 and anti-C2 Abs were significantly associated with IgG(1) and IgG(2a) isotypes, respectively. Because the IgG(2a) isotype is associated with enhanced Fc receptor-mediated effector mechanisms, this result suggests that anti-C2 Abs and inflammation may be linked. Additionally, we identified a novel class of Abs with dual specificity for the A1 and A3 domains. Forty per cent of the Abs had no detectable inhibitory activity, indicating that they are prominent and potentially pathologically significant. CONCLUSION The expanded delineation of the humoral response to FVIII may lead to improved management of hemophilia A through mutagenesis of FVIII B-cell epitopes.
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Affiliation(s)
- J F Healey
- Aflac Cancer Center and Blood Disorders Service, Department of Pediatrics, Children's Healthcare of Atlanta and Emory University, Atlanta, GA 30322, USA
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Fang H, Wang L, Wang H. The protein structure and effect of factor VIII. Thromb Res 2007; 119:1-13. [PMID: 16487577 DOI: 10.1016/j.thromres.2005.12.015] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2005] [Revised: 11/06/2005] [Accepted: 12/26/2005] [Indexed: 11/23/2022]
Abstract
Factor VIII (FVIII) is a key component of the fluid phase of the blood coagulation system. The proteases efficiently cleave FVIII at three sites, two within the heavy and one within the light chain resulting in alteration of its covalent structure and conformation and yielding the active cofactor, FVIIIa. FVIIIa is a trimer composed of A1, A2 and A3-C1-C2 subunits. The role of FVIIIa is to markedly increase the catalytic efficiency of factor IXa in the activation of factor X. Variants of these factors frequently also lead to severe bleeding disorders.
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Affiliation(s)
- Hong Fang
- Department of Cardiology, Tongji Hospital, Tongji University, Shanghai 200065, China.
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Mersich C, Billes W, Pabinger I, Jungbauer A. Peptides derived from a secretory yeast library restore factor VIII activity in the presence of an inhibitory antibody. Biotechnol Bioeng 2007; 98:12-21. [PMID: 17390380 DOI: 10.1002/bit.21426] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The development of autoantibodies against factor VIII represents one of the major complications in the treatment of hemophilia A patients. We have employed a novel library system to obtain peptides that specifically neutralize the interaction between factor VIII and these inhibitors. The random peptides are presented as carboxy-terminal extensions of the eukaryotic initiation factor 5a, an intracellular protein with a molecular mass of 18 kDa. These random peptides formed an unique binding site, as demonstrated by molecular simulations using the computer programs InsightII and GROMACS. The library was screened to identify peptides binding to the murine monoclonal anti-factor VIII antibody ESH8 and to inhibitors derived from patients with factor VIII antibodies. Ten peptides binding to ESH8 were identified. Their specificity was confirmed by displacement assays. Two peptides with the sequences STKTLGRPLHGPAGPVEGGALAGVAEDADLVTAVSGR and YHCKREDLTDRDATCALRQPPQAVRGLGPRVTAVSGR showed the ability to restore the factor VIII activity from 33% up to approximately 90% in functional tests performed in vitro. Three candidates for binding to factor VIII antibodies derived from four different patient's sera were achieved. Three fusion proteins with the peptide sequences PQLGSRRSTTPSLTFQNASWFPAGGPCARSNRG, SGSRQVCKLARSLQPF and WERGRRVGAQVRHARHLVARVLDGAGHQARLTAVNGP bound to inhibitors derived from different patients. Furthermore, two of the obtained fusion proteins with the peptide sequences RHWTALGPAPTHTCADLNYPLLS and WERGRRVGAQVRHARHLVARVLDGAGHQARLTAVNGP did also bind to the monoclonal antibody ESH8. This study demonstrates the potential of this system to identify peptides that inhibit the activity of potent inhibitory antibodies and also shows potential as a method for screening of bioactive peptides.
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Affiliation(s)
- Christa Mersich
- Department of Biotechnology, University of Natural Resources and Applied Life Sciences Vienna, Vienna, Austria
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Parker ET, Doering CB, Lollar P. A1 subunit-mediated regulation of thrombin-activated factor VIII A2 subunit dissociation. J Biol Chem 2006; 281:13922-30. [PMID: 16513639 DOI: 10.1074/jbc.m513124200] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Factor VIII (fVIII) is the plasma protein that is missing or deficient in hemophilia A. In contrast, elevated levels of fVIII are associated with an increased risk of arterial and venous thrombosis. fVIII is activated by thrombin to form a non-covalently linked A1/A2/A3-C1-C2 heterotrimer. At physiological concentrations, fVIIIa decays as a result of A2 subunit dissociation, which may help regulate the balance between hemostasis and thrombosis. A2 subunit dissociation is faster in human fVIIIa than in porcine fVIIIa, which may represent an evolutionary adaptation associated with the development of the upright posture and venous stasis in the lower extremities. To investigate the basis for the different decay kinetics of human and porcine fVIIIa, hybrid fVIII molecules representing all possible combinations of human and porcine A domains were isolated. The kinetics of fVIIIa decay were measured and fit to a model describing a reversible bimolecular reaction in which the dissociation rate constant, k, and dissociation constant, Kd, were the fitted parameters. Substitution of the porcine A1 domain into human fVIIIa produced a dissociation rate constant indistinguishable from porcine fVIIIa. Subsequently, substitution of the second cupredoxin-like A1 subdomain resulted in a dissociation rate constant similar to porcine fVIIIa, whereas substitution of the first cupredoxin-like A1 subdomain resulted in a dissociation rate constant intermediate between human and porcine fVIIIa. We propose that cupredoxin-like A1 subdomains in fVIII contain inter-species differences that are a result of selective pressure on the dissociation rate constant.
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Affiliation(s)
- Ernest T Parker
- Aflac Cancer Center and Blood Disorders Service, Children's Healthcare of Atlanta, Georgia 30322, USA
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45
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Abstract
Factor VIII, a non-covalent heterodimer comprised of a heavy chain (A1-A2-B domains) and light chain (A3-C1-C2 domains), circulates as an inactive procofactor in complex with von Willebrand factor. Metal ions are critical to the integrity of factor VIII, with Cu and Ca ions stabilizing the heterodimer and generating the active conformation, respectively. Activation of factor VIII catalyzed by thrombin appears dependent upon interactions with both anion-binding exosites I and II, and converts the heterodimer to the active cofactor, factor VIIIa. This protein, comprised of A1, A2, and A3-C1-C2 subunits, is labile due to weak affinity of the A2 subunit. Association of factor VIIIa with factor IXa to form the intrinsic factor Xase complex is membrane-dependent and involves multiple inter-protein contacts that remain poorly characterized. This complex catalyzes the conversion of factor X to factor Xa, a reaction that is essential for the propagation phase of coagulation. The role of factor VIIIa in this complex is to increase the catalytic efficiency for factor Xa generation by several orders of magnitude. Mechanisms for the down-regulation of factor Xase focus upon inactivation of the cofactor and include dissociation of the A2 subunit as well as activated protein C-catalyzed proteolysis.
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Affiliation(s)
- Philip J Fay
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine, New York 14642, USA.
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Sarafanov AG, Makogonenko EM, Pechik IV, Radtke KP, Khrenov AV, Ananyeva NM, Strickland DK, Saenko EL. Identification of Coagulation Factor VIII A2 Domain Residues Forming the Binding Epitope for Low-Density Lipoprotein Receptor-Related Protein,. Biochemistry 2006; 45:1829-40. [PMID: 16460029 DOI: 10.1021/bi0520380] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Regulation of the coagulation factor VIII (fVIII) level in circulation involves a hepatic receptor low-density lipoprotein receptor-related protein (LRP). One of two major LRP binding sites in fVIII is located within the A2 domain (A2), likely exposed within the fVIII complex with von Willebrand factor and contributing to regulation of fVIII via LRP. This work aimed to identify A2 residues forming its LRP-binding site, previously shown to involve residues 484-509. Isolated A2 was subjected to alanine-scanning mutagenesis followed by expression of a set of mutants in a baculovirus system. In competition and surface plasmon resonance assays, affinities of A2 mutants K466A, R471A, R484A, S488A, R489A, R490A, H497A, and K499A for LRP were found to be decreased by 2-4-fold. This correlated with 1.3-1.5-fold decreases in the degree of LRP-mediated internalization of the mutants in cell culture. Combining these mutations into pairs led to cumulative effects, i.e., 7-13-fold decrease in affinity for LRP and 1.6-2.2-fold decrease in the degree of LRP-mediated internalization in cell culture. We conclude that the residues mentioned above play a key role in formation of the A2 binding epitope for LRP. Experiments in mice revealed an approximately 4.5 times shorter half-life for A2 in the circulation in comparison with that of fVIII. The half-lives of A2 mutant R471A/R484A or A2 co-injected with receptor-associated protein, a classical ligand of LRP, were prolonged by approximately 1.9 and approximately 3.5 times, respectively, compared to that of A2. This further confirms the importance of the mutated residues for interaction of A2 with LRP and suggests the existence of an LRP-dependent mechanism for removing A2 as a product of dissociation of activated fVIII from the circulation.
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Affiliation(s)
- Andrey G Sarafanov
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA.
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Kopecky EM, Greinstetter S, Pabinger I, Buchacher A, Römisch J, Jungbauer A. Mapping of FVIII inhibitor epitopes using cellulose-bound synthetic peptide arrays. J Immunol Methods 2006; 308:90-100. [PMID: 16376372 DOI: 10.1016/j.jim.2005.10.016] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2005] [Revised: 07/26/2005] [Accepted: 10/03/2005] [Indexed: 11/20/2022]
Abstract
Epitope mapping using antibodies against factor VIII (FVIII) has been performed using blotting techniques with truncated and/or digested FVIII molecules. Here, we focused on the precise mapping of affinity purified IgG from patients with an immune response against blood clotting FVIII using synthetic peptide arrays on cellulose membranes comprising the entire sequence of FVIII. The aim was to elucidate the epitope profile from different inhibitors and possibly detect new epitopes, which have not been described before. The epitope patterns from five patients showed reactivity with all domains in the FVIII molecule, but were different between various patients. These results included epitopes usually buried within the folded protein. However, in competition assays using FVIII as competitive agent in a mixture with inhibitor IgG, the most immunogenic regions were located in the FVIII light chain. Our results show that the C1 domain was the region with highest immunogenicity in all patients. Here, we demonstrate that the SPOT method is very well suited for the precise location of epitopes in the core of the protein, which usually cannot be detected by other methods.
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Affiliation(s)
- Eva-Maria Kopecky
- Department of Biotechnology, University of Natural Resources and Applied Life Sciences, Muthgasse 18, A-1190 Vienna, Austria
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48
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Abstract
Factor VIII, a metal ion-dependent heterodimer, circulates in complex with von Willebrand factor. At sites of vessel wall damage, this procofactor is activated to factor VIIIa by limited proteolysis and assembles onto an anionic phospholipid surface in complex with factor IXa to form the intrinsic factor Xase; an enzyme complex that efficiently converts factor X to factor Xa during the propagation phase of coagulation. Factor Xase activity is down-regulated by mechanisms that include self-dampening by dissociation of a critical factor VIIIa subunit and proteolytic inactivation by the activated protein C pathway. Recent studies identify putative metal ion coordination sites as well as ligands involved in the catabolism of the activated and procofactor forms of the protein. Our knowledge of these multiple intra- and inter-molecular interactions has been facilitated by the application of naturally occurring and site-directed mutations to study factor VIII structure and function. In this review, we document important and novel contributions following this line of investigation.
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Affiliation(s)
- Philip J Fay
- Department of Biochemistry, School of Medicine, University of Rochester, P.O. Box 712, 601 Elmwood Ave., Rochester, NY 14642, USA.
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Hu GL, Okita DK, Conti-Fine BM. T cell recognition of the A2 domain of coagulation factor VIII in hemophilia patients and healthy subjects. J Thromb Haemost 2004; 2:1908-17. [PMID: 15550021 DOI: 10.1111/j.1538-7836.2004.00918.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Hemophilia A patients treated with coagulation factor VIII (FVIII), and also some healthy subjects, may develop anti-FVIII antibodies (Ab), whose synthesis is driven by FVIII-specific CD4+ T cells. Some Ab block the procoagulant function of FVIII (inhibitors). Many inhibitors recognize epitopes on the FVIII A2 domain. Here, we have sought to identify A2 epitopes recognized by CD4+ T cells. We tested the proliferative response of CD4+ blood lymphocytes (BL) from hemophilia patients and healthy subjects, to overlapping synthetic peptides spanning the A2 domain sequence. Many A2 peptides induced proliferative responses of CD4+ BL from one or more subjects. The peptide-induced responses were strongest in hemophilia patients with inhibitors, weakest in healthy subjects. A2 peptides comprising residues 371-400, 621-650 and 671-690 elicited frequent and strong responses in hemophilia A patients, and especially in those with inhibitors. Healthy subjects recognized frequently only the sequence 371-400. A three-dimensional model of the A2 domain suggests that these CD4+ epitope sequences have structural features typical of 'universal' CD4+ T epitopes.
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Affiliation(s)
- G-L Hu
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, USA.
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Abstract
The development of inhibitory 'allo' antibodies to a deficient coagulation factor is arguably now the most severe and important complication of clotting factor concentrate exposure in haemophilia and other congenital coagulation disorders. Furthermore, development of an inhibitor to the factor VIII or factor IX transgene product remains a significant concern in gene therapy protocols for haemophilia. Although the development of an inhibitor does not usually change the rate, initial severity or pattern of bleeding, it does compromise the ability to manage haemorrhage in affected individuals, resulting in a greater rate of complications, cost and disability. The purpose of this review is to summarize current understanding of the epidemiology, immunobiology, laboratory evaluation and management of inhibitors arising in patients with congenital coagulation disorders. An attempt has been made to focus on recent advances in the immunology of inhibitors, and to speculate on their potential clinical application.
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Affiliation(s)
- Nigel S Key
- University of Minnesota Medical School, Minneapolis, MN, USA.
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