title: MyD88 or TRAM knockdown regulates interleukin (IL)-6, IL-8, and CXCL12 mRNA expression in human gingival and periodontal ligament fibroblasts.
abstract: BACKGROUND
  In a previous report, it was shown that Toll-like receptor (TLR) 2 knockdown modulates interleukin (IL)-6 and IL-8 but not the chemokine CXCL12, an important mediator with inflammatory and proangiogenic effects, in human gingival fibroblasts (HGF) and human periodontal ligament fibroblasts (HPDLF). This study investigates whether knocking down two important TLR adaptor molecules, such as myeloid differentiation protein 88 (MyD88) and TRIF-related adaptor molecule (TRAM), could affect mRNA expression of IL-6, IL-8, and CXCL12 in HGF and HPDLF.
  
  
  METHODS
  After small interfering (si) RNA-mediated silencing of MyD88 or TRAM, HGF and HPDLF were stimulated with Porphyromonas gingivalis (Pg) lipopolysaccharide (LPS) or two synthetic ligands of TLR2 (Pam2CSK4 and Pam3CSK4) for 6 hours. IL-6, IL-8, and CXCL12 mRNAs were evaluated by quantitative polymerase chain reaction.
  
  
  RESULTS
  Knockdown of MyD88 or TRAM partially impaired the IL-8 mRNA upregulation in both fibroblast subpopulations. Similarly, IL-6 upregulation was partially prevented by siMyD88 or siTRAM in HGF stimulated with Pg LPS, as well as in both fibroblast subtypes challenged with Pam2CSK4. Conversely, constitutive CXCL12 mRNA levels were upregulated by MyD88 or TRAM knockdown in non-stimulated cells.
  
  
  CONCLUSIONS
  These results suggest that TLR adaptor molecules knockdown, such as MyD88 or TRAM, can decrease IL-6 and IL-8 mRNA and increase CXCL12 mRNA expression in HGF and HPDLF. This can be an important step for better understanding the mechanisms that control the inflammatory cytokine and chemokine expression, which in turn contributes to periodontal pathogenesis.
authors.affiliation: Department of Biological Sciences, Bauru School of Dentistry, University of São Paulo, Bauru, São Paulo, Brazil.
authors.forename: Ana Carolina
authors.initials: AC
authors.lastname: Morandini
authors.forename: Pedro Paulo
authors.initials: PP
authors.lastname: Chaves Souza
authors.forename: Erivan Schnaider
authors.initials: ES
authors.lastname: Ramos-Junior
authors.forename: Carlos Alberto
authors.initials: CA
authors.lastname: Souza Costa
authors.forename: Carlos Ferreira
authors.initials: CF
authors.lastname: Santos
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000187:drug effects / Q000235:genetics*; D000293:Adolescent; D000328:Adult; D018929:Cell Culture Techniques; D002470:Cell Survival / Q000502:physiology; D054377:Chemokine CXCL12 / Q000235:genetics*; D005260:Female; D005347:Fibroblasts / Q000276:immunology*; D005786:Gene Expression Regulation / Q000235:genetics; D055785:Gene Knockdown Techniques / Q000379:methods*; D005881:Gingiva / Q000166:cytology / Q000276:immunology*; D006801:Humans; D015850:Interleukin-6 / Q000235:genetics*; D016209:Interleukin-8 / Q000235:genetics*; D008024:Ligands; D055666:Lipopeptides / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000276:immunology; D008297:Male; D053594:Myeloid Differentiation Factor 88 / Q000187:drug effects / Q000235:genetics*; D010513:Periodontal Ligament / Q000166:cytology / Q000276:immunology*; D016966:Porphyromonas gingivalis / Q000276:immunology; D012333:RNA, Messenger / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics; D051195:Toll-Like Receptor 2 / Q000819:agonists; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics; D055815:Young Adult
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C515255:CXCL12 protein, human; C508606:CXCL8 protein, human; D054377:Chemokine CXCL12; C508600:IL6 protein, human; D015850:Interleukin-6; D016209:Interleukin-8; D008024:Ligands; D055666:Lipopeptides; D008070:Lipopolysaccharides; C507779:MYD88 protein, human; D053594:Myeloid Differentiation Factor 88; C508075:Pam(3)CSK(4) peptide; C560312:Pam2CSK4 lipopeptide; D012333:RNA, Messenger; D034741:RNA, Small Interfering; C480228:TICAM2 protein, human; D051195:Toll-Like Receptor 2