title: Identification of target antigens of anti-endothelial cell and anti-vascular smooth muscle cell antibodies in patients with giant cell arteritis: a proteomic approach.
abstract: BACKGROUND
  Immunological studies of giant cell arteritis (GCA) suggest that a triggering antigen of unknown nature could generate a specific immune response. We thus decided to detect autoantibodies directed against endothelial cells (ECs) and vascular smooth muscle cells (VSMCs) in the serum of GCA patients and to identify their target antigens.
  
  
  METHODS
  Sera from 15 GCA patients were tested in 5 pools of 3 patients' sera and compared to a sera pool from 12 healthy controls (HCs). Serum immunoglobulin G (IgG) reactivity was analysed by 2-D electrophoresis and immunoblotting with antigens from human umbilical vein ECs (HUVECs) and mammary artery VSMCs. Target antigens were identified by mass spectrometry.
  
  
  RESULTS
  Serum IgG from GCA patients recognised 162 ± 3 (mean ± SD) and 100 ± 17 (mean ± SD) protein spots from HUVECs and VSMCs, respectively, and that from HCs recognised 79 and 94 protein spots, respectively. In total, 30 spots from HUVECs and 19 from VSMCs were recognised by at least two-thirds and three-fifths, respectively, of the pools of sera from GCA patients and not by sera from HCs. Among identified proteins, we found vinculin, lamin A/C, voltage-dependent anion-selective channel protein 2, annexin V and other proteins involved in cell energy metabolism and key cellular pathways. Ingenuity pathway analysis revealed that most identified target antigens interacted with growth factor receptor-bound protein 2.
  
  
  CONCLUSIONS
  IgG antibodies to proteins in the proteome of ECs and VSMCs are present in the sera of GCA patients and recognise cellular targets that play key roles in cell biology and maintenance of homeostasis. Their potential pathogenic role remains to be determined.
authors.affiliation: Inserm U1016, Institut Cochin, CNRS UMR 8104, 8 rue Méchain, F-75014 Paris, France.
authors.forename: Alexis
authors.initials: A
authors.lastname: Régent
authors.forename: Hanadi
authors.initials: H
authors.lastname: Dib
authors.forename: Kim H
authors.initials: KH
authors.lastname: Ly
authors.forename: Christian
authors.initials: C
authors.lastname: Agard
authors.forename: Mathieu C
authors.initials: MC
authors.lastname: Tamby
authors.forename: Nicolas
authors.initials: N
authors.lastname: Tamas
authors.forename: Babette
authors.initials: B
authors.lastname: Weksler
authors.forename: Christian
authors.initials: C
authors.lastname: Federici
authors.forename: Cédric
authors.initials: C
authors.lastname: Broussard
authors.forename: Loïc
authors.initials: L
authors.lastname: Guillevin
authors.forename: Luc
authors.initials: L
authors.lastname: Mouthon
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001323:Autoantibodies / Q000276:immunology*; D001324:Autoantigens / Q000276:immunology*; D002461:Cell Line, Transformed; D002478:Cells, Cultured; D016207:Cytokines / Q000276:immunology; D015180:Electrophoresis, Gel, Two-Dimensional / Q000379:methods; D042783:Endothelial Cells / Q000166:cytology / Q000276:immunology*; D005260:Female; D013700:Giant Cell Arteritis / Q000276:immunology*; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D015151:Immunoblotting / Q000379:methods; D007074:Immunoglobulin G / Q000276:immunology; D008297:Male; D008323:Mammary Arteries / Q000166:cytology / Q000276:immunology; D013058:Mass Spectrometry / Q000379:methods; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000276:immunology*; D040901:Proteomics / Q000379:methods*; D017978:Receptors, Growth Factor / Q000276:immunology; D016596:Vinculin / Q000276:immunology
chemical_list: D001323:Autoantibodies; D001324:Autoantigens; D016207:Cytokines; D007074:Immunoglobulin G; D017978:Receptors, Growth Factor; C488955:VCL protein, human; D016596:Vinculin