Cytokines play a pivotal role in maintaining bone homeostasis. Osteoclasts (OCs), the sole bone resorbing cells, are regulated by numerous cytokines. Macrophage colony-stimulating factor and receptor activator of NF-κB ligand play a central role in OC differentiation, which is also termed osteoclastogenesis. Osteoclastogenic cytokines, including tumor necrosis factor-α, IL-1, IL-6, IL-7, IL-8, IL-11, IL-15, IL-17, IL-23, and IL-34, promote OC differentiation, whereas anti-osteoclastogenic cytokines, including interferon (IFN)-α, IFN-β, IFN-γ, IL-3, IL-4, IL-10, IL-12, IL-27, and IL-33, downregulate OC differentiation. Therefore, dynamic regulation of osteoclastogenic and anti-osteoclastogenic cytokines is important in maintaining the balance between bone-resorbing OCs and bone-forming osteoblasts (OBs), which eventually affects bone integrity. This review outlines the osteoclastogenic and anti-osteoclastogenic properties of cytokines with regard to osteoimmunology, and summarizes our current understanding of the roles these cytokines play in osteoclastogenesis.
Cytokines ; Homeostasis ; Interferons ; Interleukin-1 ; Interleukin-10 ; Interleukin-11 ; Interleukin-12 ; Interleukin-15 ; Interleukin-17 ; Interleukin-23 ; Interleukin-27 ; Interleukin-3 ; Interleukin-33 ; Interleukin-4 ; Interleukin-6 ; Interleukin-7 ; Interleukin-8 ; Macrophage Colony-Stimulating Factor ; Necrosis ; Osteoblasts ; Osteoclasts ; RANK Ligand