Inhibition of disease progression by a novel retinoid antagonist in animal models of arthritis.

Objective. To investigate the usefulness of a novel retinoic acid receptor (RAR) antagonist (BMS-189453) in animal models of arthritis. . BMS-189453 was tested in HIG-82 rabbit synovial fibroblasts to determine its ability to repress collagenase (matrix metalloproteinase-1, MMP-1) mRNA expression in vitro. Cells were stimulated with phorbol myristate acetate or interleukin 113 and mRNA quantified by slot-blot analysis. In vivo, BMS-189453 was evaluated in 2 animal models of arthritis: collagen induced arthritis (CIA) in mice and streptococcal cell wall induced arthritis (SCWA) in rats. Clinical scores for arthritis were recorded weekly. At the end of each study, limbs were evaluated histologically. In CIA, these results were correlated with mRNA levels for collagenase-3 (MMP-13) and stromelysin-1 (MMP-3) as determined by Northern blot. Results. BMS-189453 reduced MMP-1 expression in HIG-82 synovial fibroblasts in culture. BMS-189453 treatment blocked the clinical progression of arthritis beyond soft tissue inflammation in the CIA model. In the SCWA model, BMS-189453 treatment resulted in significantly reduced swelling with no notable progression to joint distortion/destruction. Histological evaluation of the joints from animals in both models confirmed this result. Analysis of mRNA from the CIA paws showed that BMS-189453 prevented the overexpression of MMP-13 and MMP-3 in arthritic joints. Conclusion. Improvement in clinical and histologic variables in 2 separate animal models, along with simultaneous reduction in MMP expression in the affected joint, suggests that RAR antagonists such as BMS-189453 may be useful as agents to treat rheumatoid arthritis and for determining the role of MMP in disease progression. This is the first study to show the clinical potential of RAR antagonists in arthritis.