Osteoclastbiology and osteoimmunology

Lorenzo et al. [1] summarized the multiple overlapping and interacting mechanisms evolved in the regulation of both bone and immune system: 1) that cells related to osteoblasts, which form bone, are critical regulators of the hematopoietic stem cell (HSC) niche from which all blood and immune cells derive; and 2) that osteoclasts, which are the cells that resorb bone, appear to share a common origin with the myeloid precursor cells that also gives rise to macrophages and myeloid dendritic cells. It has also been shown in vitro that cells that are relatively far along in their differentiation toward antigen-presenting dendritic cells retain the ability to form mature bone-resorbing osteoclasts [2]. Finally, over the last 30 yr, it has become well established that multiple soluble mediators of immune cell function including cytokines, chemokines, and growth factors also regulate osteoblast and osteoclast activity [3].

1. Lorenzo J, Horowitz M, Choi Y (2008) Osteoimmunology: interactions of the bone and immune system. Endocr Rev 29:403-440

2. Alnaeeli M, Penninger JM, Teng YT (2006) Immune interactions with CD4+ T cells promote the development of functional osteoclasts from murine CD11c+ dendritic cells. J Immunol 177:3314-3326

3. Horowitz MC, Lorenzo J, Bilezikian J, Raisz L, Rodan G (1996) Local regulators of bone: IL-1, TNF, and lymphotoxin, interferon  , IL-8, IL-10, IL-4, the LIF/IL-6 family and additional cytokines. In: Bilezikian JP, Raisz LG, Rodan GA, eds. Principals of bone biology, 2nd ed. San Diego: Academic Press; 961–977