Abstract
The biological effect of lipopolysaccharides LPS from Porphyromonas gingivalis (P. gingivalis) on murine periodontal tissue was assessed in comparison with the effect of LPS from Escherichia coli (E. coli). P. gingivalis LPS was injected into non-immunized or LPS-preimmunized mouse gingiva different numbers of times (1, 4, 7, 10, 13 or 20), and E. coli LPS was injected into non-immunized or LPS-preimmunized mouse gingiva in a similar manner. Before LPS was injected into the gingiva, serum levels of antibody against LPS were measured by enzyme-linked immunosorbent assay ELISA. Destruction of gingival tissue and osteoclastic bone resorption were assessed histopathologically. The results showed that the inflammatory changes in LPS-preimmunized mice gingiva were more severe than in non-immunized mice when E. coli LPS was injected 1 time. After 4 injections, gingival inflammation became more severe and osteoclastic bone resorption was increasingly observed equally in non-immunized and LPS -preimmunized mice . On the other hand, in the P. gingivalis LPS injection group, milder inflammatory changes and less alveolar bone resorption were observed, and there was little difference between the histological changes in the non-immunized mice and the LPS-preimmunized mice. These findings suggest that the in vivo biological activity of P. gingivalis LPS, which induces destruction of gingival tissue and osteoclastic bone resorption, is weaker than that of E. coli LPS.
