Contribution of OX40/OX40 ligand interaction to the pathogenesis of rheumatoid arthritis

OX40 ligand (OX40L) and OX40 (CD134) are a pair of cell surface molecules b elonging to the TNF/TNF receptor family. Interaction of OX40L with its rece ptor OX40 is thought to be important in T cell activation through T cell/an tigen-presenting cell interaction. However, involvement of these molecules in the pathogenesis of rheumatoid arthritis (RA) remains unclear. To explor e the contribution of OX40/OX40L interaction to the pathogenesis of RA in v ivo, we evaluated the effect of a neutralizing anti-OX40L monoclonal antibo dy (mAb) on the development of collagen-induced arthritis (CIA) in DBA/1 mi ce as an animal model for RA. Administration of anti-OX40L mAb into type II collagen (CII) -immunized DBA/1 mice dramatically ameliorated the disease severity. In vivo treatment with anti-OX40L mAb did not inhibit the expansi on of CII-reactive T cells, but suppressed IFN-gamma and anti-CII IgG2a pro duction. Therefore, OX40/OX40L interaction appears to play a critical role in the development of CIA by enhancing Th1-type autoimmune response. In add ition, T lymphocytes in synovial fluid and synovial tissue from RA patients expressed OX40, while OX40L was expressed on sublining cells in synovial t issue. These results indicate that OX40/OX40L interaction may play a critic al role in the development of RA.