Objective: Osteoimmunology investigates interactions between skeleton
and immune system. In the light of recent discoveries in this field, a new
reading register of osteoporosis is actually emerging, in which bone and immune
cells are strictly interconnected. Osteoporosis could therefore be considered a
chronic immune mediated disease which shares with other age related disorders a
common inflammatory background. Here, we highlight these recent discoveries
and the new landscape that is emerging.
Method: Extensive literature search in PubMed central.
Results: While the inflammatory nature of osteoporosis has been clearly recognized,
other interesting aspects of osteoimmunology are currently emerging. In addition, mounting
evidence indicates that the immunoskeletal interface is involved in the regulation of important
body functions beyond bone remodeling. Bone cells take part with cells of the immune system in
various immunological functions, configuring a real expanded immune system, and are therefore
variously involved not only as target but also as main actors in various pathological conditions
affecting primarily the immune system, such as autoimmunity and immune deficiencies, as well as
in aging, menopause and other diseases sharing an inflammatory background.
Conclusion: The review highlights the complexity of interwoven pathways and shared mechanisms
of the crosstalk between the immune and bone systems. More interestingly, the interdisciplinary
field of osteoimmunology is now expanding beyond bone and immune cells, defining new
homeostatic networks in which other organs and systems are functionally interconnected. Therefore,
the correct skeletal integrity maintenance may be also relevant to other functions outside its
involvement in bone mineral homeostasis, hemopoiesis and immunity.