title: Cross-reactivity between annexin A2 and Beta-2-glycoprotein I in animal models of antiphospholipid syndrome.
abstract: Antiphospholipid syndrome (APS) affects coagulation and the brain by autoimmune mechanisms. The major antigen in APS is beta-2-glycoprotein I (β2-GPI) is known to complex with annexin A2 (ANXA2), and antibodies to ANXA2 have been described in APS. We measured these antibodies in mice with experimental APS (eAPS) induced by immunization with β2-GPI. Sera of these mice reacted significantly with recombinant ANXA2 by enzyme-linked immunosorbent assay (ELISA) and the eAPS mice had significantly high levels of immunoglobulin G (IgG) in the brain by immunoblot assays compared to adjuvant immunized controls. Immunoprecipitation performed by mixing eAPS brain tissue with protein-G beads resulted in identification of two autoantigens unique to the eAPS group, one of which was ANXA2. In order to study more directly and methodically the specific role of anti-ANXA2 antibodies in APS, we immunized mice with β2-GPI which contained no ANXA2 or with ANXA2 and measured antibodies to these proteins. Levels of antibodies to ANXA2 measured by ELISA were 0.72 ± 0.007 arbitrary units (a.u), 0.24 ± 0.03 and 0.02 ± 0.01 a.u for sera from ANXA2, β2-GPI and control mice, respectively (p < 0.0001 and p = 0.037 for the comparison of the ANXA2 and β2-GPI groups to the controls). Purified IgG from β2-GPI sera did not show cross-binding with ANXA2. Antibodies to β2-GPI and phospholipids were found in the β2-GPI immunized group only. The present study suggests an immune response to the β2-GPI-ANXA2 complex in eAPS and provides a novel ANXA2 immunization model which will serve to study the role of ANXA2 antibodies in of APS.
authors.affiliation: Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel.|Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.
authors.forename: R
authors.initials: R
authors.lastname: Weiss
authors.affiliation: Department of Molecular Microbiology and Biotechnology, Tel-Aviv University, Tel Aviv, Israel.
authors.forename: A
authors.initials: A
authors.lastname: Bitton
authors.affiliation: Department of Molecular Microbiology and Biotechnology, Tel-Aviv University, Tel Aviv, Israel.
authors.forename: L
authors.initials: L
authors.lastname: Nahary
authors.affiliation: Zabludowicz Center for Autoimmune Diseases, Sheba Medical Center, 52621, Tel Hashomer, Ramat Gan, Israel.|Doctoral Program in Biomedical Sciences, Universidad del Rosario, Bogotá, Colombia.
authors.forename: M T
authors.initials: MT
authors.lastname: Arango
authors.affiliation: Department of Molecular Microbiology and Biotechnology, Tel-Aviv University, Tel Aviv, Israel.
authors.forename: I
authors.initials: I
authors.lastname: Benhar
authors.affiliation: Zabludowicz Center for Autoimmune Diseases, Sheba Medical Center, 52621, Tel Hashomer, Ramat Gan, Israel.
authors.forename: M
authors.initials: M
authors.lastname: Blank
authors.affiliation: Zabludowicz Center for Autoimmune Diseases, Sheba Medical Center, 52621, Tel Hashomer, Ramat Gan, Israel.|Incumbent of the Laura Schwarz-Kip Chair for Research of Autoimmune Diseases, Sackler Faculty of Medicine, Tel-Aviv University, 69978, Ramat Aviv, Tel Aviv, Israel.
authors.forename: Y
authors.initials: Y
authors.lastname: Shoenfeld
authors.affiliation: Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel. joab.chapman@sheba.health.gov.il.|Zabludowicz Center for Autoimmune Diseases, Sheba Medical Center, 52621, Tel Hashomer, Ramat Gan, Israel. joab.chapman@sheba.health.gov.il.|Incumbent of Robert and Martha Harden Chair in Mental and Neurological Diseases, Sackler Faculty of Medicine, Tel Aviv University, 69978, Ramat Aviv, Tel Aviv, Israel. joab.chapman@sheba.health.gov.il.|Department of Neurology, The Chaim Sheba Medical Center, Sackler Faculty of Medicine, Tel Aviv University, 52621, Tel Hashomer, Israel. joab.chapman@sheba.health.gov.il.
authors.forename: J
authors.initials: J
authors.lastname: Chapman
mesh_terms: D000818:Animals; D017306:Annexin A2 / Q000276:immunology*; D017152:Antibodies, Antiphospholipid / Q000097:blood; D016736:Antiphospholipid Syndrome / Q000097:blood / Q000276:immunology*; D001921:Brain / Q000276:immunology; D003429:Cross Reactions; D004195:Disease Models, Animal; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D007074:Immunoglobulin G / Q000097:blood; D008807:Mice, Inbred BALB C; D053482:beta 2-Glycoprotein I / Q000276:immunology*
chemical_list: D017306:Annexin A2; D017152:Antibodies, Antiphospholipid; D007074:Immunoglobulin G; D053482:beta 2-Glycoprotein I
keywords: Annexin; Anticardiolipin; Antiphospholipid syndrome; Autoantibodies; Autoimmune; Beta-2-glycoprotein