Stimulatory effect on bone resorption of interleukin-1-like cytokine produced by an osteoblast-rich population of mouse calvarial cells.

We reported previously that an osteoblast-rich population of mouse calvarial cells treated with lipopolysaccharide produced on interleukin-1 (IL-1)-like cytokine that closely resembles IL-1. In the present study, we examined whether or not the IL-1-like cytokine stimulates bone resorption. As a result we found that the cytokine stimulate bone resorption significantly, and the stimulatory effect was dependent on cytokine dose and length of culture time. The stimulation of bone resorption and IL-1-like cytokine activity appear to be in parallel. Since the stimulatory effect of the cytokine was not abolished in the presence of indomethacin, the cytokine may stimulate bone resorption in a prostaglandin metabolite-independent manner. These results suggest the possibility that the IL-1-like cytokine may be involved as an autoregulatory factor in the bone-remodeling system.