title: Lipopolysaccharide-regulated production of bone sialoprotein and interleukin-8 in human periodontal ligament fibroblasts: the role of toll-like receptors 2 and 4 and the MAPK pathway.
abstract: OBJECTIVE
  Lipopolysaccharide (LPS) on the cell wall of periodontal pathogens is a major mediator of the inflammatory response and can enhance alveolar bone resorption in periodontitis. Bone sialoprotein is an early marker of osteoblast differentiation. The proinflammatory cytokine, interleukin-8 (IL-8), induces osteoclast differentiation, maturation and maintenance of bone resorption activity. However, the effects of LPS from periodontal pathogens on the expression of bone sialoprotein and IL-8 in human osteoblasts and the mechanism of periodontal bone metabolism regulation are rather unclear. The objectives of this study were to determine the effects of Porphyromonas gingivalis LPS on the production of bone sialoprotein and IL-8 in human periodontal ligament fibroblasts (hPDLFs), and to investigate whether toll-like receptor (TLR) 2, TLR4 and MAPKs pathways are involved in the regulation of production of bone sialoprotein and IL-8 by P. gingivalis LPS.
  
  
  METHODS
  The third-generation of hPDLFs were cultured with mineralization-inducing culture medium. After hPDLFs were treated with P. gingivalis LPS, bone sialoprotein and IL-8 mRNA expression were detected using Real time PCR. Then hPDLFs were transiently transfected with siTLR2 or siTLR4 (20 nm) or inhibited by MAPK signaling pathways inhibitors, and then bone sialoprotein and IL-8 mRNA and protein expression were also detected using Real time PCR and western blotting.
  
  
  RESULTS
  Treatments with 0.01 and 0.1 mg/L of P. gingivalis LPS for 8 h up-regulated bone sialoprotein mRNA expression, whereas 10 and 100 mg/L of P. gingivalis LPS induced a significant decrease in the expression of bone sialoprotein mRNA. In contrast, IL8 mRNA levels were increased significantly by 10 mg/L of P. gingivalis LPS. Interestingly, small interfering RNA (siRNA) knock down of the TLR2 and ERK1/2 inhibitor, PD98059, abolished the effects of P. gingivalis LPS on the bone sialoprotein mRNA level, whereas siRNA knock down of the TLR2 and p38 MAPK inhibitor, SB203580, blocked the effect of P. gingivalis LPS on IL-8 in hPDLFs.
  
  
  CONCLUSIONS
  This study suggests that in hPDLFs, P. gingivalis LPS suppresses bone sialoprotein and enhances IL-8 gene and protein expression via TLR2 and ERK1/2 or the p38 MAPK signaling pathway, respectively.
authors.affiliation: Department of Periodontology, Tianjin Stomatological Hospital, Tianjin, China.
authors.forename: Y
authors.initials: Y
authors.lastname: Zhang
authors.forename: X
authors.initials: X
authors.lastname: Li
mesh_terms: D000293:Adolescent; D002113:Calcification, Physiologic / Q000187:drug effects; D018929:Cell Culture Techniques; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005347:Fibroblasts / Q000187:drug effects; D005419:Flavonoids / Q000494:pharmacology; D055785:Gene Knockdown Techniques; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D058574:Integrin-Binding Sialoprotein / Q000187:drug effects*; D016209:Interleukin-8 / Q000187:drug effects*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D020935:MAP Kinase Signaling System / Q000187:drug effects*; D010513:Periodontal Ligament / Q000166:cytology / Q000187:drug effects*; D016966:Porphyromonas gingivalis / Q000502:physiology*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology; D034741:RNA, Small Interfering / Q000235:genetics; D051195:Toll-Like Receptor 2 / Q000187:drug effects* / Q000235:genetics; D051197:Toll-Like Receptor 4 / Q000187:drug effects* / Q000235:genetics; D055815:Young Adult
chemical_list: C508606:CXCL8 protein, human; D004791:Enzyme Inhibitors; D005419:Flavonoids; D007093:Imidazoles; D058574:Integrin-Binding Sialoprotein; D016209:Interleukin-8; D008070:Lipopolysaccharides; D047428:Protein Kinase Inhibitors; D011725:Pyridines; D034741:RNA, Small Interfering; C495342:TLR2 protein, human; C495345:TLR4 protein, human; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; C093642:SB 203580; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one
keywords: bone sialoprotein, interleukin 8; human periodontal ligament fibroblasts; lipopolysaccharide