The effect of interleukin-1β, tumour necrosis factor α and particle phagocytosis on monocyte-osteoclast differentiation

Abstract

Interleukin-1 (IL-1) and tumour necrosis factor (TNF) are inflammatory cytokines which are known to influence osteoclastic bone resorption. To determine the effect of these cytokines on inflammatory macrophage-osteoclast differentiation, we added IL-1β and TNFα to long term co-cultures of mouse monocytes and osteoblastic cells. IL-1β (10 and 100 pg/ml) stimulated osteoclast formation as measured by expression of TRAP and the extent of lacunar bone resorption whereas TNFα (10 and 100 ng/ml) inhibited macrophage-osteoclast differentiation and bone resorption. Particle phagocytosis (which is known to stimulate the release of these cytokines) did not influence the extent of osteoclast formation. IL-1β stimulation of osteoclast formation may in part account for the increase in bone resorption associated with this inflammatory cytokine; TNFα inhibition of osteoclast formation may be due to interruption of the interaction between osteoblasts and osteoclast precursors