Description

Since its origin, the field of research identified as “osteoimmunology” encompasses an increasing number of topics and nowadays, encompasses many aspects of the crosstalk between bone and the immune system in various physiopathological conditions. A large part of research has long been focused on the effects elicited by adaptive immunity on bone, with rheumatoid arthritis as a prototypical disease condition. More recently however, the role of the innate arm of the immune system in bone homeostasis and disorders has received increasing attention. For example, (i) osteal macrophages have emerged as active and plastic players in skeletal remodeling and repair; (ii) dendritic cells have been demonstrated to be potential osteo-immune modulators, particularly in inflammation-induced bone loss, via their innate effector functions and their influence on adaptive immunity; (iii) mast cells exert pro-osteoclastogenic functions in inflammatory conditions; and (iv) complement signaling influences the activity of both osteoblasts and osteoclasts and their interaction. In parallel, novel concepts for specific bone cell types in regulating immunity have been proposed, such as osteoclasts as professional antigen presenting cells and inflammatory osteoclasts as a different population compared to homeostatic osteoclasts.

The overall picture on the interplay between innate immunity and bone remains highly complex and poorly understood. Advanced biofunctional systems combining diverse cell types and ad-hoc designed biomaterials are currently exploited in in vitro and in vivo studies to dig into this complexity by unravelling the cellular mechanisms, signaling pathways, metabolic factors and other molecular mediators, that tune cell fate and regulate immune responses, with the view of eventually developing innovative strategies for regenerative medicine applications.

In this Research Topic, we aim to focus on osteoimmunology from the perspective of the crosstalk between innate immune cells and bone cells. Namely, we will address: (i) recent advances in the elucidation of the roles of innate immunity in bone homeostasis and repair; (ii) emerging immunological functions of bone cells; (iii) current and emerging biotechnological approaches to dissect osteo-immunological interactions in a physiologically relevant engineered microenvironment and (iv) translational studies built upon this knowledge.