[IL-6 inhibitors prevent bone loss and cartilage degeneration in rheumatoid arthritis]

Dysregulation of cytokines, including interleukin-6 (IL-6), is involved in joint destruction in rheumatoid arthritis (RA). The concentration of IL-6 is increased not only in the affected joints but also in the serum. Locally, IL-6 provides the formation of pannus through the synthesis of vascular endothelial growth factor (VEGF). In addition, IL-6 contributes to the production of matrix metalloproteinases which digest collagen and proteoglycan of cartilage. Furthermore, IL-6 induces the differentiation and activation of osteoclasts. IL-6 can be delivered systemically to a similar extent as hormones, may induce systemic osteoporosis. Tocilizumab (TCZ), a humanized anti-IL-6 receptor antibody, inhibiting IL-6 signaling, has provided beneficial outcomes, such as achievement of clinical remission, protective effects against bone and cartilage destruction. Because of the beneficial outcomes, new drugs inhibiting IL-6 signaling are developed, and the clinical trials are ongoing.