INFLAMMATORY CYTOKINE GENE-EXPRESSION IN HUMAN PERIODONTAL-LIGAMENT FIBROBLASTS STIMULATED WITH BACTERIAL LIPOPOLYSACCHARIDES

The effects of Porphyromonas gingivalis lipopolysaccharide (P-LPS) and Escherichia coli lipopolysaccharide (E-LPS) on the gene expression and production of inflammatory cytokines of human periodontal ligament fibroblasts (HPLF) were examined by a Northern (RNA blot) assay and enzyme-linked immunosorbent assay, respectively. mRNAs for interleukin-6 (IL-6), IL-8, and transforming growth factor beta (TGP-P) were detected in HPLF cells, but IL-1 alpha, IL-1 beta, tumor necrosis factor alpha, transforming growth factor alpha, and granulocyte-macrophage colony-stimulating factor were not detected by reverse transcription-PCR. The expression of TGF-P mRNA was not influenced by either LPS, P-LPS (1 to 10 mu g/ml) and E-LPS (100 mu g/ml) markedly stimulated the expression of IL-6 and IL-8 mRNAs compared with the control. The synthesis of IL-6 and IL-8 was also stimulated by 10 and 100 mu g of both LPSs per mi, but IL-8 synthesis was not stimulated with E-LPS at 1 mu g/ml. Secretion of IL-6 and IL-8 into the culture medium was detected at 6 and 3 h, respectively, after exposure to P-LPS (10 mu g/ml). These findings suggested that P. gingivalis leads to periodontal tissue destruction and alveolar bone resorption through IL-6 and IL-8 released from HPLF cells stimulated with its LPS.