The bone-resorbing activities in tissue culture of lipopolysaccharides from the bacteria Actinobacillus actinomycetemcomitans, Bacteroides gingivalis and Capnocytophaga ochracea isolated from human mouths.

The activities of lipopolysaccharides (LPS) were assessed by measuring the calcium release from mouse calvaria in vitro and compared to that of LPS from Salmonella typhimurium. Stimulation of bone resorption was maximal at an LPS concentration of 10 micrograms/ml and at this dose all oral LPS preparations showed similar levels of activity and less than that of LPS from S. typhimurium. Only S. typhimurium LPS and B. gingivalis LPS retained bone-resorbing activity at 0.1 microgram/ml. No bone-resorbing activity was observed against killed bone and histochemical observations of stable acid phosphatase activity indicated both mononuclear and multinuclear cells participating in bone removal. Addition of indomethacin to the culture medium did not inhibit calcium release from the bones by any of the LPS preparations except for that from A. actinomycetemcomitans. Fetal calf serum completely blocked the activities of all the LPS preparations whereas human serum did not inhibit the action of B. gingivalis LPS. Thus this particular LPS could be important in mediating bone loss in chronic periodontitis.