1994 Volume 40 Issue 1 Pages 52-60
We examined whether osteoblasts and bone marrow stromal cells mediate the effect of LPS (10μg/ml) and heparin (5μg/ml) in chick osteoclast activity in vitro, using disaggregated osteoclast resorption assay. LPS stimulated osteoclasts to excavate bone in culture without serum. The stimulation was blocked by cyclosporin A (0.1μ8/ml), but not indomethacin (10-5M). Although heparin elicited osteoclastic bone resorption with or without serum, cyclosporin A and indomethacin suppressed these stimulatory effects. Using the antibodies against : interleukin-1 (IL-1), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α) and tumor necrosis factor-beta (TNF-β), TNF-α antibody blunted the effect of LPS or heparin to chick osteoclastic bone resorption, whereas the antibodies against IL-1, IL-6 and TNF-β had no effect on LPS or heparin stimulation. Moreover, the osteoclasts cocultured bone marrowderived stromal cells (ST2) or clonal osteogenic cells (MC3T3-E1) and pretreated with LPS for 24hrs, showed increased activity, which was inhibited by TNF-α antibody. These results suggest that LPS and heparin cause an increase in bone resorption in vitro by releasing TNF-α from osteoblasts and bone marrow stromal cells.
