title: Proof-of-concept study demonstrating the pathogenicity of affinity-purified IgG antibodies directed to domain I of β2-glycoprotein I in a mouse model of anti-phospholipid antibody-induced thrombosis.
abstract: OBJECTIVE
  IgG aPL against domain I of β2-glycoprotein I (β2GPI) [anti-DI (aDI)] is associated with the pathogenesis of APS, an autoimmune disease defined by thrombosis and pregnancy morbidity. To date, however, no study has demonstrated direct pathogenicity of IgG aDI in vivo. In this proof-of-concept study, we designed a novel system to affinity purify polyclonal aDI aPL in order to assess its prothrombotic ability in a well-characterized mouse microcirculation model for APS.
  
  
  METHODS
  Two polyclonal IgG fractions were isolated from serum of a patient with APS, both with high aPL activity but differing in aDI activity (aDI-rich and aDI-poor). These IgG fractions were tested for their pathogenic ability in an in vivo mouse model of thrombosis. Male CD1 mice were injected intraperitoneally with either aDI-rich or aDI-poor IgG; as a control, IgG isolated from healthy serum was used. A pinch injury was applied to the right femoral vein and thrombus dynamics and tissue factor activity in isolated tissue were evaluated.
  
  
  RESULTS
  Both aDI-rich and aDI-poor IgG retained aCL and anti-β2GPI activity, while only aDI-rich IgG displayed high aDI activity, as defined by our in-house cut-offs for positivity in each assay. aDI-rich IgG induced significantly larger thrombi in vivo compared with aDI-poor IgG (P < 0.0001). Similarly, aDI-rich IgG significantly enhanced the procoagulant activity of carotid artery endothelium and peritoneal macrophages isolated from experimental animals (P < 0.01).
  
  
  CONCLUSIONS
  These data directly demonstrate that the ability to cause thrombosis in vivo is concentrated in the aDI fraction of aPL.
authors.affiliation: Centre for Rheumatology Research, Division of Medicine, University College London, London, UK, Division of Rheumatology, Department of Internal Medicine, University of Texas Medical Branch, Galveston, TX, USA, Structural Biology, Medical Research Council National Institute for Medical Research and Arthritis Research UK Centre for Adolescent Rheumatology, University College London Hospital and Great Ormond Street Hospital, London, UK.
authors.forename: Charis
authors.initials: C
authors.lastname: Pericleous
authors.affiliation: Centre for Rheumatology Research, Division of Medicine, University College London, London, UK, Division of Rheumatology, Department of Internal Medicine, University of Texas Medical Branch, Galveston, TX, USA, Structural Biology, Medical Research Council National Institute for Medical Research and Arthritis Research UK Centre for Adolescent Rheumatology, University College London Hospital and Great Ormond Street Hospital, London, UK.
authors.forename: Patricia
authors.initials: P
authors.lastname: Ruiz-Limón
authors.affiliation: Centre for Rheumatology Research, Division of Medicine, University College London, London, UK, Division of Rheumatology, Department of Internal Medicine, University of Texas Medical Branch, Galveston, TX, USA, Structural Biology, Medical Research Council National Institute for Medical Research and Arthritis Research UK Centre for Adolescent Rheumatology, University College London Hospital and Great Ormond Street Hospital, London, UK.
authors.forename: Zurina
authors.initials: Z
authors.lastname: Romay-Penabad
authors.affiliation: Centre for Rheumatology Research, Division of Medicine, University College London, London, UK, Division of Rheumatology, Department of Internal Medicine, University of Texas Medical Branch, Galveston, TX, USA, Structural Biology, Medical Research Council National Institute for Medical Research and Arthritis Research UK Centre for Adolescent Rheumatology, University College London Hospital and Great Ormond Street Hospital, London, UK.
authors.forename: Ana Carrera
authors.initials: AC
authors.lastname: Marín
authors.affiliation: Centre for Rheumatology Research, Division of Medicine, University College London, London, UK, Division of Rheumatology, Department of Internal Medicine, University of Texas Medical Branch, Galveston, TX, USA, Structural Biology, Medical Research Council National Institute for Medical Research and Arthritis Research UK Centre for Adolescent Rheumatology, University College London Hospital and Great Ormond Street Hospital, London, UK.
authors.forename: Acely
authors.initials: A
authors.lastname: Garza-Garcia
authors.affiliation: Centre for Rheumatology Research, Division of Medicine, University College London, London, UK, Division of Rheumatology, Department of Internal Medicine, University of Texas Medical Branch, Galveston, TX, USA, Structural Biology, Medical Research Council National Institute for Medical Research and Arthritis Research UK Centre for Adolescent Rheumatology, University College London Hospital and Great Ormond Street Hospital, London, UK.
authors.forename: Lucy
authors.initials: L
authors.lastname: Murfitt
authors.affiliation: Centre for Rheumatology Research, Division of Medicine, University College London, London, UK, Division of Rheumatology, Department of Internal Medicine, University of Texas Medical Branch, Galveston, TX, USA, Structural Biology, Medical Research Council National Institute for Medical Research and Arthritis Research UK Centre for Adolescent Rheumatology, University College London Hospital and Great Ormond Street Hospital, London, UK.
authors.forename: Paul C
authors.initials: PC
authors.lastname: Driscoll
authors.affiliation: Centre for Rheumatology Research, Division of Medicine, University College London, London, UK, Division of Rheumatology, Department of Internal Medicine, University of Texas Medical Branch, Galveston, TX, USA, Structural Biology, Medical Research Council National Institute for Medical Research and Arthritis Research UK Centre for Adolescent Rheumatology, University College London Hospital and Great Ormond Street Hospital, London, UK.
authors.forename: David S
authors.initials: DS
authors.lastname: Latchman
authors.affiliation: Centre for Rheumatology Research, Division of Medicine, University College London, London, UK, Division of Rheumatology, Department of Internal Medicine, University of Texas Medical Branch, Galveston, TX, USA, Structural Biology, Medical Research Council National Institute for Medical Research and Arthritis Research UK Centre for Adolescent Rheumatology, University College London Hospital and Great Ormond Street Hospital, London, UK.
authors.forename: David A
authors.initials: DA
authors.lastname: Isenberg
authors.affiliation: Centre for Rheumatology Research, Division of Medicine, University College London, London, UK, Division of Rheumatology, Department of Internal Medicine, University of Texas Medical Branch, Galveston, TX, USA, Structural Biology, Medical Research Council National Institute for Medical Research and Arthritis Research UK Centre for Adolescent Rheumatology, University College London Hospital and Great Ormond Street Hospital, London, UK.
authors.forename: Ian
authors.initials: I
authors.lastname: Giles
authors.affiliation: Centre for Rheumatology Research, Division of Medicine, University College London, London, UK, Division of Rheumatology, Department of Internal Medicine, University of Texas Medical Branch, Galveston, TX, USA, Structural Biology, Medical Research Council National Institute for Medical Research and Arthritis Research UK Centre for Adolescent Rheumatology, University College London Hospital and Great Ormond Street Hospital, London, UK. Centre for Rheumatology Research, Division of Medicine, University College London, London, UK, Division of Rheumatology, Department of Internal Medicine, University of Texas Medical Branch, Galveston, TX, USA, Structural Biology, Medical Research Council National Institute for Medical Research and Arthritis Research UK Centre for Adolescent Rheumatology, University College London Hospital and Great Ormond Street Hospital, London, UK.
authors.forename: Yiannis
authors.initials: Y
authors.lastname: Ioannou
authors.affiliation: Centre for Rheumatology Research, Division of Medicine, University College London, London, UK, Division of Rheumatology, Department of Internal Medicine, University of Texas Medical Branch, Galveston, TX, USA, Structural Biology, Medical Research Council National Institute for Medical Research and Arthritis Research UK Centre for Adolescent Rheumatology, University College London Hospital and Great Ormond Street Hospital, London, UK.
authors.forename: Anisur
authors.initials: A
authors.lastname: Rahman
authors.affiliation: Centre for Rheumatology Research, Division of Medicine, University College London, London, UK, Division of Rheumatology, Department of Internal Medicine, University of Texas Medical Branch, Galveston, TX, USA, Structural Biology, Medical Research Council National Institute for Medical Research and Arthritis Research UK Centre for Adolescent Rheumatology, University College London Hospital and Great Ormond Street Hospital, London, UK. c.pericleous@ucl.ac.uk.
authors.forename: Silvia S
authors.initials: SS
authors.lastname: Pierangeli
mesh_terms: D000818:Animals; D017152:Antibodies, Antiphospholipid / Q000276:immunology / Q000494:pharmacology*; D016736:Antiphospholipid Syndrome / Q000139:chemically induced* / Q000150:complications / Q000276:immunology; D004195:Disease Models, Animal; D007074:Immunoglobulin G / Q000276:immunology / Q000494:pharmacology*; D008297:Male; D051379:Mice; D017434:Protein Structure, Tertiary; D013927:Thrombosis / Q000139:chemically induced* / Q000150:complications / Q000276:immunology; D053482:beta 2-Glycoprotein I / Q000276:immunology*
chemical_list: D017152:Antibodies, Antiphospholipid; D007074:Immunoglobulin G; D053482:beta 2-Glycoprotein I
keywords: anti-phospholipid antibodies; anti-phospholipid syndrome; domain I; mouse model; venous thrombosis; β2-glycoprotein I