Toll-like receptor 4-mediated signal pathway induced by Porphyromonas gingivalis lipopolysaccharide in human gingival fibroblasts.
The lipopolysaccharide (LPS) secreted by Porphyromonas gingivalis is implicated in the initiation and progression of periodontitis. Human gingival fibroblasts (HGFs) are the major constituent of gingival connective tissue. In this study, we examined the expression of Toll-like receptor 4 (TLR4) on HGFs by flow cytometric analysis, and studied the signal transduction induced by LPS stimulation of HGFs by enzyme-linked immunosorbent assay, Western blotting, and immunoprecipitation. We show that LPS binds to HGFs, and that HGFs express TLR4 and myeloid differentiation primary response gene 88 (MyD88). P. gingivalis LPS-induced interleukin (IL)-1 production in HGFs was inhibited by anti-TLR4 antibody. P. gingivalis LPS treatment of HGFs activated several intracellular proteins including protein tyrosine kinases, and upregulated the expression of IL-1 receptor-associated kinase (IRAK), nuclear factor-kappaB (NF-kappaB), and activating protein-1 (AP-1), and these events were suppressed by anti-TLR4 monoclonal antibody. Our findings suggest that the binding of P. gingivalis LPS to TLR4 on HGFs activates various second messenger systems.
Wang
P L
PL
Department of Pharmacology, Osaka Dental University, 8-1 Kuzuhahanazono-cho Hirakata, Osaka, 573-1121, Japan. wang@cc.osaka-dent.ac.jp
Azuma
Y
Y
Shinohara
M
M
Ohura
K
K
D000911:Antibodies, Monoclonal / Q000276:immunology; D001483:Base Sequence; D015342:DNA Probes; D029721:Drosophila Proteins; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism; D005881:Gingiva / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D008070:Lipopolysaccharides / Q000378:metabolism / Q000494:pharmacology*; D008562:Membrane Glycoproteins / Q000276:immunology / Q000502:physiology*; D016966:Porphyromonas gingivalis / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000276:immunology / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology*; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors
D000911:Antibodies, Monoclonal; D015342:DNA Probes; D029721:Drosophila Proteins; D008070:Lipopolysaccharides; D008562:Membrane Glycoproteins; D011956:Receptors, Cell Surface; C495345:TLR4 protein, human; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors