Identification of Target Antigens of Anti-Endothelial Cell Antibodies in Patients with ANCA-Associated Systemic Vasculitis: A Proteomic Approach

Alexis Régent¹, Hanadi Dib², Guillaume Bussone¹, Mathieu C. Tamby¹, Nicolas Tamas², Christian Federici³, Cédric Broussard³, Loic Guillevin⁴ and Luc Mouthon¹, ¹Internal Medicine, Hopital Cochin, Paris, France, ²Université Paris Descartes, Paris, France, ³Institut Cochin, INSERM U1016, CNRS UMR 8104, Université Paris Descartes, Paris, France, ⁴Department of Internal Medicine, Referral Center for Rare Autoimmune and Systemic Diseases, Hôpital Cochin, AP–HP, Université Paris Descartes, Paris, France, Paris, France

Meeting: 2012 ACR/ARHP Annual Meeting

Keywords: ANCA, autoantibodies, autoantigens and vasculitis, B cells

Session Information

Title: B-cell Biology and Targets in Autoimmune Disease

Session Type: Abstract Submissions (ACR)

Background/Purpose: Anti-endothelial cell antibodies (AECA) are frequently detected in anti-neutrophil cytoplasm antibodies (ANCA)-associated systemic vasculitis (AAV) and are considered to play pathological roles but their antigenic specificities are still unknown. We used a proteomic approach combining two-dimensional electrophoresis and immunoblotting to identify the target antigens of AECA in patients with ANCA-associated vasculitis.

Methods: Sera from 30 ANCA-associated vasculitis patients (12 with Granulomatosis with polyangeitis (GPA), 9 with microscopic polyangeitis (MPA), 9 with Churg Strauss syndrome (CSS)), tested in pools of 3 sera, were compared to a sera pool from 12 healthy controls (HC). Serum IgG reactivity was analyzed by use of a 2-D electrophoresis and immunoblotting technique with normal human umbilical vein endothelial cell (HUVEC) antigens.

Results: Serum IgG in the HC sera pool recognized 85 protein spots and serum IgG from patients with AAV recognized 134±65 different protein spots. We focused on protein recognized by at least 3/4 pools of patients with GPA and 2/3 pools of patients with MPA and CSS and not by HC and identified 20, 7 and 8 proteins, respectively. In addition, among the 330 spots recognized by at least one pool of patients with AAV, ten different spots were recognized by at least 6/10 pools. Among identified proteins, IgG reactivity was detected against alpha-enolase, lamin A/C and protein disulfide-isomerase A3. Interestingly, Ingenuity Pathway Analysis revealed that most of these antigens interact with TGF-β, immunoglobins and inflammatory complexes such as Jun and MAPK

Conclusion: AECA detected in patients with AAV recognize cellular targets playing key roles in cell biology. Target antigens interact with protein and complexes known to play a crucial role in AAV pathophysiology.

Disclosure:

A. Régent,
None;

H. Dib,
None;

G. Bussone,
None;

M. C. Tamby,
None;

N. Tamas,
None;

C. Federici,
None;

C. Broussard,
None;

L. Guillevin,
None;

L. Mouthon,
None.

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