AB0136 The effect of il-6 receptor antibody for the treatment of mch-lpr/lpr-ra1 mice that spontaneously developed ankylosing arthritis

Background McH-lpr/lpr-RA1 (RA1) mice are new strain mice which spontaneously developed arthritis in ankle and finally leads to ankylosis.1 There is no report that drug treatment has been applied to these mice. Objectives To examine the effect of mouse IL-6 receptor antibody MR16–1 for the treatment of RA-1 mice. Methods Male RA1 mice were randomly divided into treated and control groups. MR 16–1 was applied from 10 weeks of age for the treatment group. Saline was applied for the control group. The drug was administered every two weeks with the initial dose of 2 mg, then 0.5 mg. The effects were evaluated by histological synovitis score, in vivo imaging using ICG-encapsulated liposomes and the expression of serum SAA and IL-6. Results The tissue evaluation was carried out at 14 weeks, 17 weeks and 20 weeks of age. The histological score of treated groups were significantly improved compared with control group at every age. The interclass correlation coefficient was 0.771. In vivo imaging using ICG-encapsulated liposomes showed that significant signal decrease in treated groups at 14 weeks, but no significant difference was observed after 16 weeks. Blood SAA was significantly improved at 17 weeks of age. Conclusions IL-6 receptor antibody is effective for the treatment of ankylosing arthritis of RA1 mice. IL-6 might be a new potential target of treatment for ankylosing arthritis. Reference [1] Mori S, Tanda N, Ito MR, et al. Novel recombinant congenic mouse strain developing arthritis with enthesopathy. Pathol Int2008;58:407–414. Disclosure of Interest None declared