Porphyromonas gingivalis lipopolysaccharide activated bone resorption of osteoclasts by inducing IL-1, TNF, and PGE.

AIM

To study the effects of Porphyromonas gingivalis lipopolysaccharide (Pg-LPS) on inducing interleukin-1 (IL-1), tumor necrosis factor (TNF), prostaglandin E (PGE), and activating osteoclasts, in order to understand mechanism of osteoclast activation.

METHODS

Pg-LPS was prepared by phenol-water method. IL-1, TNF, and PGE induced by Pg-LPS were isolated by chromatography. Ca2+ concentration was detected by atomic absorption spectrophotometry. Acid phosphatase and carbonic anhydrase in periodontal membranes were examined by histochemistry.

RESULTS

Pg-LPS was able to stimulate peripheral blood mononuclear cells (PBMC) or the cells from human periodontal tissue secreting IL-1, TNF, and PGE. The outputs of these cytokines were increased in pace with the enhancement of Pg-LPS at the dose range of 0.5 - 5.0 mg/L. All of the three cytokines showed activities of accelerating Ca2+ release from rat calvarial bones, and the activity of PGE was the strongest. The amounts of both the acid phosphatase and carbonic anhydrase in the periodontal membranes of Pg-LPS injected rats were obviously increased (P < 0.01). In the periodontal membranes of Pg-LPS injected rats, the amount of activated osteoclasts were obviously increased in pace with Pg-LPS injection times (P < 0.01). However, the activating rates of osteoclasts were stable to approximately 65 % because of the increase of inactivated osteoclasts.

CONCLUSION

Pg-LPS possessed strong activities to induce human PBMC and the cells from human periodontal tissue to produce IL-1, TNF, and PGE in a dose-dependent m anner within a certain concentration range of the LPS. Pg-LPS could efficiently activate osteoclasts, and the mechanism of osteoclast activation was probably associated with the increase of acid phosphatase and carbonic anhydrase.