Safari, FatemehFatemehSafari0000-0001-5060-8186Yeoh, Wen JieWen JieYeoh0000-0001-5406-8471Perret-Gentil-dit-Maillard, SaskiaSaskiaPerret-Gentil-dit-MaillardKlenke, Frank M.Frank M.KlenkeDolder, SilviaSilviaDolderHofstetter, WilhelmWilhelmHofstetterKrebs, PhilippePhilippeKrebs0000-0003-4918-66542024-10-262024-10-262024-05https://boris-portal.unibe.ch/handle/20.500.12422/174665Inflammation and skeletal homeostasis are closely intertwined. Inflammatory diseases are associated with local and systemic bone loss, and post-menopausal osteoporosis is linked to low-level chronic inflammation. Phosphoinositide-3-kinase signalling is a pivotal pathway modulating immune responses and controlling skeletal health. Mice deficient in Src homology 2-containing inositol phosphatase 1 (SHIP1), a negative regulator of the phosphoinositide-3-kinase pathway, develop systemic inflammation associated with low body weight, reduced bone mass, and changes in bone microarchitecture. To elucidate the specific role of the immune system in skeletal development, a genetic approach was used to characterise the contribution of SHIP1-controlled systemic inflammation to SHIP1-dependent osteoclastogenesis. Lymphocyte deletion entirely rescued the skeletal phenotype in Rag2 -/- /Il2rg -/- /SHIP1 -/- mice. Rag2 -/- /Il2rg -/- /SHIP1 -/- osteoclasts, however, displayed an intermediate transcriptomic signature between control and Rag2 +/+ /Il2rg +/+ /SHIP1 -/- osteoclasts while exhibiting aberrant in vitro development and functions similar to Rag2 +/+ /Il2rg +/+ /SHIP1 -/- osteoclasts. These data establish a cell-intrinsic role for SHIP1 in osteoclasts, with inflammation as the key driver of the skeletal phenotype in SHIP1-deficient mice. Our findings demonstrate the central role of the immune system in steering physiological skeletal development.en500 - Science::570 - Life sciences; biology600 - Technology::610 - Medicine & healtharticle10.48350/1931893838817310.26508/lsa.202302297