New developments in osteoimmunology.

Investigations into interactions between the skeletal and immune systems were developed during research into arthritis, with characterization of T-cell-mediated regulation of osteoclastogenesis. A new interdisciplinary field--osteoimmunology--was created, and has since expanded to encompass disciplines including signal transduction, stem cell niches and fundamental immunology. We have witnessed rapid progress in understanding the mechanisms of bone damage in arthritis and the roles of immune molecules in bone, but comparatively less evidence has been provided for the role of bone-derived factors in the immune system. Nevertheless, regulation of immune cells, including haematopoietic stem cells, by bone cells is now a hot topic in this field. Here, I discuss recent advances in osteoimmunology and emerging avenues of basic and clinical investigation.