Antibodies against citrullinated proteins enhance tissue injury in experimental autoimmune arthritis
Kristine A. Kuhn, … , William H. Robinson, V. Michael Holers
Kristine A. Kuhn, … , William H. Robinson, V. Michael Holers
Published April 3, 2006
Citation Information: J Clin Invest. 2006;116(4):961-973. https://doi.org/10.1172/JCI25422.
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Research Article Autoimmunity

Antibodies against citrullinated proteins enhance tissue injury in experimental autoimmune arthritis

Abstract

Antibodies against citrullinated proteins are specific and predictive markers for rheumatoid arthritis although the pathologic relevance of these antibodies remains unclear. To investigate the significance of these autoantibodies, collagen-induced arthritis (CIA) in mice was used to establish an animal model of antibody reactivity to citrullinated proteins. DBA/1J mice were immunized with bovine type II collagen (CII) at days 0 and 21, and serum was collected every 7 days for analysis. Antibodies against both CII and cyclic citrullinated peptide, one such citrullinated antigen, appeared early after immunization, before joint swelling was observed. Further, these antibodies demonstrated specific binding to citrullinated filaggrin in rat esophagus by indirect immunofluorescence and citrullinated fibrinogen by Western blot. To evaluate the role of immune responses to citrullinated proteins in CIA, mice were tolerized with a citrulline-containing peptide, followed by antigen challenge with CII. Tolerized mice demonstrated significantly reduced disease severity and incidence compared with controls. We also identified novel murine monoclonal antibodies specific to citrullinated fibrinogen that enhanced arthritis when coadministered with a submaximal dose of anti-CII antibodies and bound targets within the inflamed synovium of mice with CIA. These results demonstrate that antibodies against citrullinated proteins are centrally involved in the pathogenesis of autoimmune arthritis.

Authors

Kristine A. Kuhn, Liudmila Kulik, Beren Tomooka, Kristin J. Braschler, William P. Arend, William H. Robinson, V. Michael Holers

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Figure 3

Mice tolerized with a citrullinated peptide are significantly protected from CIA.

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Mice tolerized with a citrullinated peptide are significantly protected ...
(A and B) Six- to eight-week-old male DBA/1J mice were tolerized to OVA (n = 19), CII (n = 16), LXP (n = 16), or LKP (n = 12). After challenging these mice with immunization of CII in CFA, disease severity (A) and incidence (B) were measured. (C) Paws from mice in each tolerance group were analyzed for histologic parameters of arthritis as described in Methods. (D) Anti-CII antibodies were measured by ELISA, and (E) antibodies against citrullinated fibrinogen were determined by Western blot. All data are shown as group averages α SEM. Statistical significance was determined by 1-way ANOVA. *P < 0.05; **P < 0.01 in comparison with the OVA and LKP groups. (F) Sera from tolerized mice were applied to synovial antigen arrays to characterize the autoantibody response. The relative reactivities for the labeled antigens in a pool of sera from 9 mice in each LXP- and LKP-tolerized group are shown, as is the clustering of mice based on the relationships of antibody reactivity betwe the mice.