Triantafyllopoulou and Diefenbach will analyse innate immune circuits for bone maintenance and regeneration. There is ample evidence that in tissues other than bone, innate lymphoid cells (ILC) and myeloid cell crosstalk plays a major role in tissue regeneration. Triantafyllopoulou and Diefenbach will investigate the role of the microbiota and type I interferons in regulating osteoclast development and maintenance. They hypothesise that the balance of bone marrow resident ILC1, secreting TNF and IFNγ and ILC2, secreting type 2 cytokines, crucially regulate macrophage precursor cell fate decisions in the bone marrow and thus osteoclastogenesis. Their goal is to determine the role of the microbiota-ILC-osteoclast progenitor axis in bone regeneration under physiological conditions and in the context of compromised healing.