LAUSR

Objective: Rheumatoid arthritis (RA) is a disease that typically induces secondary osteoporosis, which increases the risk of bone fractures. Anti-interleukin-6 (IL-6) receptor antibody is used to treat RA; however, its effect on bone strength is not clear. Therefore, we investigated the influence of MR16-1, an anti-mouse IL-6 receptor antibody, on bone structure and femoral strength in a collagen-induced arthritis (CIA) mouse model. Method: DBA/1J mice were immunized by intradermal injection of bovine type II collagen. MR16-1 was administered intraperitoneally at the same time as immunization. Thirty-five days after the first immunization, bone structure and bone strength were measured by micro-computed tomography and the three-point bending test. Results: In the CIA group, most bone mineral density and bone structure parameters in the foot, femur, and lumbar spine were significantly lower than in the normal group. Moreover, the maximum load of the femoral shaft in the CIA group was significantly lower than in the normal group. MR16-1 treatment significantly prevented the CIA-induced deterioration of bone structure and loss of bone strength. Conclusion: These results suggest that CIA systemically induces a deterioration of bone structure and loss of bone strength, and that IL-6 signalling plays an important role in these processes.