In vitro inhibition of lipopolysaccharide-induced bone resorption by polymyxin B

Lipopolysaccharide (LPS) purified from Haemophilus actinomycetemcomitans stimulates resorption and inhibits collagen synthesis in mouse calvaria bones in vitro. Addition of polymyxin B caused a dose-related inhibition of LPS-stimulated bone resorption and reversal of the inhibition of collagen synthesis. A polymyxin B to LPS ratio of 2:1 prevented bone resorption and restored collagen synthesis to control levels. The activity of polymyxin B was specific for LPS as bone resorption induced by prostaglandin E2 or parathyroid hormone was unaffected at similar concentrations. These results indicate that polymyxin B and its analogues may have potential in the treatment of periodontal disease by reducing bone loss induced by lipopolysaccharides.