Treponema denticola peptidoglycan induces the production of inflammatory mediators and matrix metalloproteinase 9 in macrophage-like cells.
OBJECTIVE
Treponema denticola is a key pathogen associated with periodontitis, a chronic inflammatory disease affecting tooth-supporting tissues. In the present study, we investigated the response of human macrophage-like cells to stimulation by peptidoglycan isolated from T. denticola. We also studied the effect of the peptidoglycan preparation on the phosphorylation state of kinases.


METHODS
Monoblastic leukemia cells (U937 strain) were differentiated into adherent macrophage-like cells using phorbol myristic acid prior to being stimulated for 6 or 24 h with various amounts of T. denticola peptidoglycan. Secreted inflammatory mediators were quantified by enzyme-linked immunosorbent assays. The phosphorylation state of kinases was determined by immunoblotting.


RESULTS
The T. denticola peptidoglycan preparation, which was non-toxic for macrophage-like U937 leukemia cells at the concentration used, significantly increased, in a dose-dependent manner, the secretion of the pro-inflammatory cytokines tumor necrosis factor alpha, interleukin-1beta and interleukin-6. It also increased the secretion of two potent chemokines, interleukin-8 (IL-8) and regulated on activation normal T cell expressed and secreted (RANTES). T. denticola peptidoglycan also induced a significant increase in the secretion of prostaglandin E(2) and matrix metalloproteinase 9 by macrophage-like cells. The phosphorylation state of several kinases, including extracellular regulated protein-serine kinase 2 (+99%), G protein-coupled receptor-serine kinase 2 (+50%), Yes-related protein-tyrosine kinase (+44%) and extracellular regulated protein-serine kinase 1 (+30%) also increased following stimulation with the peptidoglycan preparation.


CONCLUSIONS
T. denticola peptidoglycan activates intracellular signaling pathways, leading to an increased production of inflammatory mediators by macrophage-like cells.
Tanabe
S-I
SI
Groupe de Recherche en Ecologie Buccale, Faculté de Médecine Dentaire, Université Laval, Quebec City, Quebec, Canada.
Bodet
C
C
Grenier
D
D
D002454:Cell Differentiation; D045744:Cell Line, Tumor; D002470:Cell Survival; D018946:Chemokine CCL5 / Q000032:analysis; D015232:Dinoprostone / Q000032:analysis; D054769:G-Protein-Coupled Receptor Kinase 2 / Q000032:analysis; D006801:Humans; D018836:Inflammation Mediators / Q000032:analysis*; D053583:Interleukin-1beta / Q000032:analysis; D015850:Interleukin-6 / Q000032:analysis; D008213:Lymphocyte Activation / Q000276:immunology; D008264:Macrophages / Q000276:immunology*; D020780:Matrix Metalloproteinase 9 / Q000032:analysis*; D019950:Mitogen-Activated Protein Kinase 1 / Q000032:analysis; D048052:Mitogen-Activated Protein Kinase 3 / Q000032:analysis; D010457:Peptidoglycan / Q000276:immunology*; D010518:Periodontitis / Q000382:microbiology; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000032:analysis; D013601:T-Lymphocytes / Q000276:immunology; D013997:Time Factors; D048373:Treponema denticola / Q000276:immunology*; D014409:Tumor Necrosis Factor-alpha / Q000032:analysis; D019061:src-Family Kinases / Q000032:analysis
C483024:CCL5 protein, human; D018946:Chemokine CCL5; D018836:Inflammation Mediators; D053583:Interleukin-1beta; D015850:Interleukin-6; D010457:Peptidoglycan; D014409:Tumor Necrosis Factor-alpha; C060902:lyn protein-tyrosine kinase; D019061:src-Family Kinases; D017346:Protein Serine-Threonine Kinases; C496567:GRK2 protein, human; D054769:G-Protein-Coupled Receptor Kinase 2; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020780:Matrix Metalloproteinase 9; D015232:Dinoprostone