Table 2.

The role of classical pro-inflammatory cytokines in osteoimmunology.

Pro-inflammatory cytokines	Cellular sources	Role in bone biology
IL-6	OBs, OCs, Stromal cells, OYs, DCs, ILCs Macrophages, etc.	RANK-L mediated OCs activation, OCs transmigration (43, 44)
TNF-α	Osteoblast, T cells, B cells, macrophages, monocytes, NK cells, etc.	Increases RANK expression on the macrophage (45), increases RANKL production by the stromal cell (45), induces sclerostin in OYs (46), expand OCP pool (47), inhibiting differentiation, proliferation, and activities of osteoblast (48–50), degradation of osterix (48), inhibits differentiation of MSCs (50)
IFN-γ	T cells, NK cells, B cells, ILC1, Neutrophils, Monocytes, Macrophages, MSCs, etc.	Fusion of OCs, T cell activation (51)
IL-1β	Osteoblast, T cells, B cells, Macrophages, etc.	OCs migration and activation (52–54) Plasminogen cathepsin-B and collagenase secretion (55), Downregulation ALP (56)