Treatment of collagen-induced arthritis with an anti-osteopontin monoclonal antibody through promotion of apoptosis of both murine and human activated T cells.
OBJECTIVE
To test the effects of a novel monoclonal antibody (mAb) against human osteopontin (OPN) in the prevention and treatment of collagen-induced arthritis (CIA) and to elucidate the underlying mechanisms of these effects.


METHODS
DBA/1J mice immunized with type II collagen to induce CIA were monitored to assess the effects of anti-OPN mAb on the clinical severity of the disease, and pathologic changes in the joints were examined histologically. The effects of anti-OPN mAb on survival of activated T cells from arthritic mice and from the synovial fluid of patients with rheumatoid arthritis (RA) were determined by TUNEL assay or annexin V assay. The levels of apoptosis-related proteins (Bim, Bax, and Bcl-2) and NF-kappaB were detected by immunoblot analysis.


RESULTS
One anti-OPN mAb, 23C3, was effective in inhibiting the development of CIA and even reversing established disease in DBA/1J mice. Monoclonal antibody 23C3 reduced the levels of serum type II collagen-specific autoantibodies and proinflammatory cytokines, and suppressed T cell recall responses to type II collagen. Mechanistic studies demonstrated that OPN prevented the death of type II collagen-activated murine T cells and synovial T cells from RA patients. Monoclonal antibody 23C3 promoted apoptosis of the activated T cells, particularly CD4+ T cells, by inhibiting activation of NF-kappaB and by altering the balance among the proapoptotic proteins Bim and Bax and the antiapoptotic protein Bcl-2. Screening of a phage display peptide library led to identification of the epitope ATWLNPDPSQKQ as being recognized by this novel antibody.


CONCLUSIONS
Because of its ability to effectively promote apoptosis of activated T cells, mAb 23C3 may be a novel therapeutic agent for the treatment of RA.
Fan
Kexing
K
Second Military Medical University, Shanghai, China.
Dai
Jianxin
J
Wang
Hao
H
Wei
Huafeng
H
Cao
Zhiguo
Z
Hou
Sheng
S
Qian
Weizhu
W
Wang
Huaqing
H
Li
Bohua
B
Zhao
Jian
J
Xu
Huji
H
Yang
Chengde
C
Guo
Yajun
Y
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D001168:Arthritis / Q000188:drug therapy* / Q000276:immunology; D001172:Arthritis, Rheumatoid / Q000188:drug therapy; D003094:Collagen / Q000276:immunology; D006801:Humans; D008297:Male; D051379:Mice; D008811:Mice, Inbred DBA; D053495:Osteopontin / Q000276:immunology*; D013583:Synovial Membrane / Q000276:immunology; D013601:T-Lymphocytes / Q000187:drug effects* / Q000502:physiology
D000911:Antibodies, Monoclonal; D053495:Osteopontin; D003094:Collagen