Bone resorption and local interleukin-1 alpha and interleukin-1 beta synthesis induced by Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis lipopolysaccharide

Different types of periodontopathic bacterial lipopolysaccharide (LPS) exer t various biological activities in vitro. However, whether or not these act ivities also occur in vivo remains unclear, Thus the present study investig ates bone resorption, as well as local IL-1 alpha and IL-1 beta synthesis i nduced by Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis LPS in the periodontal tissue of mice. Both types of LPS were injected int o mouse gingiva every 48 h and the animals were sacrificed 6 h after the 1s t, 4th, 7th, 10th, 13th, 16th, 20th, or 24th injection. Bone resorption in the injected gingiva was histopathologically and histomorphometrically inve stigated and local concentrations of IL-1 alpha and IL-1 beta were detected using an enzyme-linked immunosorbent assay. The active resorption ratio wa s significantly higher in the group given the 10th injection of LPS from A. actinomycetemcomitans than in the group given P. gingivalis LPS. Furthermo re, A. actinomycetemcomitans LPS stimulated significantly more synthesis of IL-1 alpha than P. gingivalis LPS after the 4th and 10th injections, and o f IL-1 beta after the 4th, 7th, 10th, 13th, 16th and 20th injections. These results suggest that A. actinomycetemcomitans LPS is a more potent inducer of bone resorption and synthesis of IL-1 alpha and IL-1 beta in the short term than P. gingivalis LPS.