Miho Suzuki1, Keisuke Tanaka1, Hiroto Yoshida1, Kenji Yogo2, Yoshihiro Matsumoto1. 1. Product Research Department, Fuji-Gotemba Research Laboratories, Chugai Pharmaceutical Co., Ltd., Shizuoka, Japan. 2. Product Research Department, Fuji-Gotemba Research Laboratories, Chugai Pharmaceutical Co., Ltd., Shizuoka, Japan. yogoknj@chugai-pharm.co.jp.
Abstract
OBJECTIVES: Obese rheumatoid arthritis patients often have higher disease activity and a poorer response to treatment than do non-obese patients. The present study aims to clarify the influence of obesity on the action of IL-6 and to evaluate the efficacy of IL-6 signalling blockade in arthritis with obesity. METHODS: Mice were fed a high-fat diet for 5 weeks, and the influence of this diet on macrophages and type II collagen-induced arthritis was investigated. RESULTS: The mice fed the high-fat diet showed greater expression of macrophage marker F4/80, not only in subcutaneous fat but also in knee synovium and the calcaneal region, than did the mice fed a normal diet. Furthermore, macrophages isolated from mice on the high-fat diet tended to show higher expression of cyclooxygenase-2 following IL-6 stimulation than did macrophages from mice fed the normal diet. Moreover, mice fed the normal or high-fat diet were immunised with type II collagen, and were treated with anti-mouse IL-6 receptor antibody (MR16-1). The anti-arthritis effect of MR16-1 was not reduced in mice fed the high-fat diet compared to mice fed the normal diet (inhibition ratio: 87% vs. 62%). Furthermore, at the peak of arthritis, cyclooxygenase-2 expression in the calcaneal region of mice fed the high-fat diet was higher than that in the mice fed the normal diet. CONCLUSIONS: These results suggested that a high-fat diet induces inflammatory changes in the synovium. We demonstrated that IL-6 signalling blockade by an anti-IL-6 receptor antibody can be effective in treating arthritis, even with obesity.
OBJECTIVES:Obese rheumatoid arthritispatients often have higher disease activity and a poorer response to treatment than do non-obesepatients. The present study aims to clarify the influence of obesity on the action of IL-6 and to evaluate the efficacy of IL-6 signalling blockade in arthritis with obesity. METHODS:Mice were fed a high-fat diet for 5 weeks, and the influence of this diet on macrophages and type II collagen-induced arthritis was investigated. RESULTS: The mice fed the high-fat diet showed greater expression of macrophage marker F4/80, not only in subcutaneous fat but also in knee synovium and the calcaneal region, than did the mice fed a normal diet. Furthermore, macrophages isolated from mice on the high-fat diet tended to show higher expression of cyclooxygenase-2 following IL-6 stimulation than did macrophages from mice fed the normal diet. Moreover, mice fed the normal or high-fat diet were immunised with type II collagen, and were treated with anti-mouseIL-6 receptor antibody (MR16-1). The anti-arthritis effect of MR16-1 was not reduced in mice fed the high-fat diet compared to mice fed the normal diet (inhibition ratio: 87% vs. 62%). Furthermore, at the peak of arthritis, cyclooxygenase-2 expression in the calcaneal region of mice fed the high-fat diet was higher than that in the mice fed the normal diet. CONCLUSIONS: These results suggested that a high-fat diet induces inflammatory changes in the synovium. We demonstrated that IL-6 signalling blockade by an anti-IL-6 receptor antibody can be effective in treating arthritis, even with obesity.