[Prospects of treatment using interferon for bone diseases]

Osteoblasts and osteoclasts produce a variety of cytokines to maintain bone homeostasis. One of the most important cytokines, receptor activator of nuclear factor-IkappaB ligand (RANKL), is essential for osteoclastogenesis. Recently, it was shown that activated T cells promote osteoclastogenesis through RANKL expression and also negatively affect osteoclastogenesis through interferon (IFN)-gamma production. Additionally, it was revealed that IFN-beta was involved in osteoclast regulation by signaling cross-talk with RANKL and that it contributed to the maintenance of normal bone mass. These studies indicate that there are complex regulatory interactions between bone-remodeling cells and immune cells, which depend on the balance between RANKL and IFN. Thus, the interaction between T cells and bone cells could be physiologically critical for the maintenance of normal bone metabolism, and IFN might be an attractive cytokine for use in therapy for bone disease in pathological bone resorptive conditions such as rheumatoid arthritis, osteoporosis, osteomyelitis and bone metastasis of cancers.