Abstract

The long-term objectives of this project are to identify and characterize pathogenic anticardiolipin antibodies (aCL) in the antiphospholipid syndrome (APS). Recently, we found 4/5 patient-derived, prothrombotic, monoclonal IgG aCL bind to plasmin, thrombin and activated protein C (APC). Of these 4 plasmin-reactive aCL, CL15 inhibits plasmin-mediated fibrinolysis and anticoagulant activity of APC, and causes fetal loss when injected into pregnant mice. It binds to plasmin with a relative Kd value of 7 x 10/-10 that is 3-4 logs higher than the affinity of IgG anti-beta2GPI antibodies (Ab) toward beta2GPI, the major autoantigen in APS. These data lead us to hypothesize that plasmin is an important autoantigen that drives certain IgG aCL in some APS patients, and that some of the plasmin-driven IgG aCL are prothrombotic (like CL15). To test these hypotheses, the specific aims are: 1. To study the prevalence, characteristics and pathogenic significance of the plasmin-reactive IgG aCL in APS patients. IgG will be purified and analyzed for Ab against CL and plasmin, and by cross inhibition to determine the presence of plasmin-reactive IgG aCL. The plasmin-reactive IgG aCL will be affinity purified and analyzed for binding affinity to plasmin, reactivity with thrombin an APC, and for lupus anticoagulant activity and pathogenicity. 2. To immunize mice with human plasmin and study the induced Ab and the pregnancy outcomes. Blood samples will be analyzed for IgG Ab against human plasmin and CL, and by cross inhibition to determine the presence of plasmin-reactive IgG aCL. Female mice with high titers of plasmin-reactive IgG aCL will be mated and the pregnancy outcomes will be examined to assess the pathogenicity of the plasmin-reactive IgG aCL. 3. To generate and study monoclonal plasmin-reactive aCL from immunized mice. The monoclonal Ab will be injected (individually or in pairs) into pregnant mice to study their pathogenic potentials, and be analyzed for reactivity with murine plasmin, and human thrombin and APC, and for relevant functional activity.

  Funding Agency

Agency
National Institute of Health (NIH)
Institute
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Type
Research Project (R01)
Project #
5R01AR042506-08
Application #
6886792
Study Section
Human Embryology and Development Subcommittee 1 (HED)
Program Officer
Gretz, Elizabeth
Project Start
1996-02-25
Project End
2008-03-31
Budget Start
2005-04-01
Budget End
2006-03-31
Support Year
8
Fiscal Year
2005
Total Cost
$271,480
Indirect Cost

  Institution

Name
University of California Los Angeles
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
092530369
City
Los Angeles
State
CA
Country
United States
Zip Code
90095

  Publications

Chen, P P; Wu, M; Hahn, B H (2010) Some antiphospholipid antibodies bind to various serine proteases in hemostasis and tip the balance toward hypercoagulant states. Lupus 19:365-9
Yang, Yao-Hsu; Chien, Daniel; Wu, Meifang et al. (2009) Novel autoantibodies against the activated coagulation factor IX (FIXa) in the antiphospholipid syndrome that interpose the FIXa regulation by antithrombin. J Immunol 182:1674-80
Ede, Kaleo; Hwang, Kwan-Ki; Wu, Chen-Ching et al. (2009) Plasmin immunization preferentially induces potentially prothrombotic IgG anticardiolipin antibodies in MRL/MpJ mice. Arthritis Rheum 60:3108-17
Pierangeli, Silvia S; Chen, Pojen P; Raschi, Elena et al. (2008) Antiphospholipid antibodies and the antiphospholipid syndrome: pathogenic mechanisms. Semin Thromb Hemost 34:236-50
Chen, P P; Yang, C D; Ede, K et al. (2008) Some antiphospholipid antibodies bind to hemostasis and fibrinolysis proteases and promote thrombosis. Lupus 17:916-21
Lin, Wei-Shiang; Chen, Pei-Chih; Yang, Cheng-De et al. (2007) Some antiphospholipid antibodies recognize conformational epitopes shared by beta2-glycoprotein I and the homologous catalytic domains of several serine proteases. Arthritis Rheum 56:1638-47
Chen, Xiao-Xiang; Gu, Yue-Ying; Li, Shu-Jie et al. (2007) Some plasmin-induced antibodies bind to cardiolipin, display lupus anticoagulant activity and induce fetal loss in mice. J Immunol 178:5351-6
Vega-Ostertag, Mariano; Liu, Xiaowei; Kwan-Ki, Hwang et al. (2006) A human monoclonal antiprothrombin antibody is thrombogenic in vivo and upregulates expression of tissue factor and E-selectin on endothelial cells. Br J Haematol 135:214-9
Yang, Yao-Hsu; Hwang, Kwan-Ki; FitzGerald, John et al. (2006) Antibodies against the activated coagulation factor X (FXa) in the antiphospholipid syndrome that interfere with the FXa inactivation by antithrombin. J Immunol 177:8219-25
Lu, Cai-Sheng; Horizon, Arash A; Hwang, Kwan-Ki et al. (2005) Identification of polyclonal and monoclonal antibodies against tissue plasminogen activator in the antiphospholipid syndrome. Arthritis Rheum 52:4018-27

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