Evaluation of inflammatory change and bone erosion using a murine type II collagen-induced arthritis model

The exact mechanism of rheumatoid arthritis (RA) is unclear, but a combination of genetic, environmental and hormonal factors is thought to be involved. This study examined the progressive arthritic reaction of murine type II collagen-induced arthritis (CIA), a representative animal model of RA. Arthritic reactions, including inflammation and bone erosion were examined using an objective non-invasive method. Two scoring systems were used to evaluate changes in cutaneous inflammation and bone erosion during RA progression. The severity of inflammation was evaluated by visual scoring of erythema and edema, while the degree of bone erosion was quantified by macroradiographical erosion analysis of specific bones. A significant difference was observed in both visual (P = 0.0001, n = 7) and radiographic (P < 0.0001, n = 7) examinations for the RA group as compared to the control. The relationship between inflammatory change and erosive change in bone showed a significant positive correlation, r = 0.9550 (P < 0.0001, n = 7). The overall rate of asymmetry was 25.23% in both fore- and hindpaws. The results generated from these experiments show that murine CIA is a promising model for elucidating the mechanism of RA. In addition, the results of this study may be used for monitoring RA progression as well as screening therapy efficacy in the joint pathology.