[CITATION][C] Perspectives: Interleukin‐6: An osteotropic factor?

GD Roodman - Journal of Bone and Mineral Research, 2020 - academic.oup.com
Journal of Bone and Mineral Research, 2020academic.oup.com
IL-6 is a recently described multifunctional cytokine that may have profound effects on bone.
It has been called many different names including BSF-2, 26 kD protein, interferon-@,,
hybridoma-plasmacytoma growth factor, and hepatocyte stimulating It is produced by a
variety of cell^(^-^) and has multiple biologic activities both in vivo and in~ itro.(~-~~) Several
lines of evidence suggest that IL-6 may be an osteotropic factor. IL-6 levels are increased in
the synovial fluid of patients with rheumatoid arthritis and other inflammatory In addition, IL-6 …
IL-6 is a recently described multifunctional cytokine that may have profound effects on bone. It has been called many different names including BSF-2, 26 kD protein, interferon-@,, hybridoma-plasmacytoma growth factor, and hepatocyte stimulating It is produced by a variety of cell^(^-^) and has multiple biologic activities both in vivo and in~ itro.(~-~~)
Several lines of evidence suggest that IL-6 may be an osteotropic factor. IL-6 levels are increased in the synovial fluid of patients with rheumatoid arthritis and other inflammatory In addition, IL-6 has been implicated as a mediator for the effects of interleukin-1,(24) a potent stimulator of bone resorption. Thus, IL-6 is an excellent candidate for an osteotropic factor. Feyen and coworkers were one of the first groups to demonstrate that osteoblasts produced IL-6 and that parathyroid hormone (PTH) enhanced the production of IL-6 by osteobla~ ts.(~~) They showed that PTH markedly increased IL-6 bioactivity in murine osteoblasts from neonatal mouse calvariae. However, PTH did not increase IL-6 production by the human osteosarcoma cell line SaOS-2, even though IL-6 activity was increased in SaOS cells in the presence of interleukin-1 or phorbol ester. Fang and Hahn (26’showed that IL-6 stimulated the growth of UMR-106-01 osteoblast-like cells. IL-6 induced a dose-dependent increase in tritiated thymidine incorporation in these cells. A minimum of 10 ng/ml of IL-6 was required to significantly increase thymidine incorporation in these cells, although the increase in thymidine incorporation was modest. These workers further showed that 1L-6 modestly decreased collagen and noncollagen protein synthesis in UMR cells. Similarly, Lowik and showed that UMR-106 cells produced IL-6 and that PTH and PTH-related peptide protein stimulated the production of IL-6 in a dose-dependent manner.
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