Inflammatory Stimulation of Porphyromonas Gingivalis Lipopolysaccharide on Human Gingival Fibroblasts

Objective To explore the effect and mechanism of Porphyromonas gingivalis (P. g) lipopolysaccharide (LPS) on the secretion of inflammatory cytokines in human gingival fibroblasts (HGFs). Methods HGFs were cultured in vitro. Tumor necrosis factor (TNF)-α and interleukin (IL)-1β were examined by enzyme-linked immunosorbent assay (ELISA) in HGFs at 6 h and 12 h after stimulation with different concentration of LPS (1 mg/L, 10 mg/L). Meanwhile, the expressions of toll-like receptor (TLR) 2 and TLR 4 in HGFs were examined by real-time PCR. Results Compared with control group (without LPS stimulation), the expression of TLR2 and secretions of TNF-α and IL-1β in HGFs were enhanced significantly at 6 h, 12 h after stimulation of LPS in P. g LPS group , with concentration-dependent manner (P 0.05). The secretions of TNF-α and IL-1β showed time-dependent manner after P. g LPS stimulation (P 0.05). The expression of TLR4 was enhanced significantly at 6 h after P. g LPS stimulation in a concentration-dependent manner (P 0.05). There was no significant difference in the expression of TLR4 at 12 h after LPS stimulation between P. g LPS group and control group (P 0.05). Conclusion Porphyromonas gingivalis LPS stimulates HGFs to secrete inflammatory cytokines mainly through TLR2 and TLR4 at early stage. The expression of TLR2 plays an important role in inflammatory reaction induced by P. g LPS in HGFs.