title: Signaling pathways activation by primary endodontic infectious contents and production of inflammatory mediators.
abstract: BACKGROUND
  This study investigated the bacterial community involved in primary endodontic diseases, evaluated its ability to activate the macrophage Toll-like receptor 4 receptor through p38 mitogen-activated protein kinase (MAPK) and nuclear factor kappa B (NF-κB) signaling pathways, and determined the levels of endotoxins and interleukins (interleukin [IL]-6 and -10) produced by endodontic content-stimulated macrophages.
  
  
  METHODS
  Samples were taken from 21 root canals by using sterile/apyrogenic paper points. Raw 264.7 macrophages were stimulated with root canal contents. Checkerboard DNA-DNA hybridization was used for bacterial analysis and the limulus amebocyte lysate assay for endotoxin measurement; p38 MAPK and NF-κB activation was determined by Western blot analysis. IL-6 and IL-10 were measured using the enzyme-linked immunosorbent assay.
  
  
  RESULTS
  Bacteria and endotoxins were detected in 100% of the samples (21/21). The most frequently observed species were Parvimonas micra (16/21, 76%), Fusobacterium nucleatum ssp. nucleatum (15/21, 71%), and Porphyromonas endodontalis (14/21, 66%). Correlations were found between endotoxins and IL-6 and IL-10 (P < .05); p38 phosphorylation had a peak at 60 minutes, and NF-κB was quickly activated after 10 minutes of stimulation.
  
  
  CONCLUSIONS
  It was concluded that the complex bacterial community was shown to be a potent activator of TLR-4 determined by the p38 MAPK and NF-κB signaling pathways, culminating in a high antigenicity against macrophages through the levels of IL-6 and IL-10, all significantly affected by endotoxin levels.
authors.affiliation: Department of Restorative Dentistry, Endodontics Division, UNESP-UNIV Estadual Paulista, São José dos Campos Dental School, São José dos Campos, São Paulo, Brazil; Department of Restorative Dentistry, Endodontics Division, Piracicaba Dental School, State University of Campinas, UNICAMP, Piracicaba, São Paulo, Brazil.
authors.forename: Frederico C
authors.initials: FC
authors.lastname: Martinho
authors.affiliation: Department of Semiology and Clinics, Periodontics Division, Federal University of Pelotas, School of Dentistry, UFPel, Pelotas, Rio Grande do Sul, Brazil.
authors.forename: Fabio R M
authors.initials: FR
authors.lastname: Leite
authors.affiliation: Department of Restorative Dentistry, Endodontics Division, Amazonas State University, Manaus, Amazonas, Brazil.
authors.forename: Wanderson M M
authors.initials: WM
authors.lastname: Chiesa
authors.affiliation: Department of Semiology and Clinics, Periodontics Division, Federal University of Pelotas, School of Dentistry, UFPel, Pelotas, Rio Grande do Sul, Brazil.
authors.forename: Gustavo G
authors.initials: GG
authors.lastname: Nascimento
authors.affiliation: Dental Research Division, Department of Periodontology, Guarulhos University, Guarulhos, São Paulo, Brazil.
authors.forename: Magda
authors.initials: M
authors.lastname: Feres
authors.affiliation: Department of Restorative Dentistry, Endodontics Division, Piracicaba Dental School, State University of Campinas, UNICAMP, Piracicaba, São Paulo, Brazil. Electronic address: bpgomes@fop.unicamp.br.
authors.forename: Brenda P F A
authors.initials: BP
authors.lastname: Gomes
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000942:Antigens, Bacterial / Q000276:immunology; D002460:Cell Line; D003786:Dental Pulp Cavity / Q000382:microbiology; D003790:Dental Pulp Necrosis / Q000276:immunology / Q000382:microbiology*; D004731:Endotoxins / Q000032:analysis; D005674:Fusobacterium Infections / Q000276:immunology; D016967:Fusobacterium nucleatum / Q000276:immunology / Q000302:isolation & purification; D016905:Gram-Negative Bacterial Infections / Q000276:immunology; D016908:Gram-Positive Bacterial Infections / Q000276:immunology; D006801:Humans; D018836:Inflammation Mediators / Q000276:immunology*; D016753:Interleukin-10 / Q000032:analysis; D015850:Interleukin-6 / Q000032:analysis; D008264:Macrophages / Q000276:immunology*; D008875:Middle Aged; D016328:NF-kappa B / Q000276:immunology; D010462:Peptostreptococcus / Q000276:immunology / Q000302:isolation & purification; D045202:Porphyromonas endodontalis / Q000276:immunology / Q000302:isolation & purification; D015398:Signal Transduction / Q000276:immunology*; D013997:Time Factors; D051197:Toll-Like Receptor 4 / Q000276:immunology; D055815:Young Adult; D048051:p38 Mitogen-Activated Protein Kinases / Q000032:analysis
chemical_list: D000942:Antigens, Bacterial; D004731:Endotoxins; C508609:IL10 protein, human; C508600:IL6 protein, human; D018836:Inflammation Mediators; D015850:Interleukin-6; D016328:NF-kappa B; C495345:TLR4 protein, human; D051197:Toll-Like Receptor 4; D016753:Interleukin-10; D048051:p38 Mitogen-Activated Protein Kinases
keywords: Endotoxin; interleukin; macrophage; root canal; signaling pathways