Effects of a chemotactic factor and Bacteroides fragilis lipopolysaccharide on bone resorption in tissue culture.

Release of previously incorporated 45Ca from fetal rat bone in tissue culture was stimulated by preparations of the polymorphonuclear leukocyte chemotactic factor isolated from lipopolysaccharide (LPS)-induced inflammatory exudate in rabbits as well as by Bacteroides fragilis LPS. High concentrations of released hydroxyproline and lactate seemed to correlate well as a high percentage of 45Ca liberated into the culture medium. An active bone resorption was stimulated by a concentration of 1 microgram/ml of the chemotactic factor. The peak in amount of released 45Ca was at a concentration of 5 micrograms/ml of the chemotactic factor (LPS-CF) as well as of the LPS preparation, whereas the parathyroid hormone was most active at 1 IU/ml. Their effect was connected with the formation of osteoclasts. Neither LPS-CF nor LPS stimulated a release of 45Ca or hydroxyproline from heat-devitalized bones. Heparin added to LPS-CF did not enhance its resorptive potential, whereas when added to LPS it had a synergistic effect. It is suggested that the bone resorptive effect exerted by LPS may be caused by chemotactic factors elaborated by activation of the complement system, and that these factors may be of importance in the pathophysiology of periodontal disease.