title: Tetra- and penta-acylated lipid A structures of Porphyromonas gingivalis LPS differentially activate TLR4-mediated NF-κB signal transduction cascade and immuno-inflammatory response in human gingival fibroblasts.
abstract: BACKGROUND
  Porphyromonas gingivalis is a major pathogen of periodontal disease that affects a majority of adults worldwide. Increasing evidence shows that periodontal disease is linked to various systemic diseases like diabetes and cardiovascular disease, by contributing to increased systemic levels of inflammation. Lipopolysaccharides (LPS), as a key virulent attribute of P. gingivalis, possesses significant amount of lipid A heterogeneity containing tetra- (LPS1435/1449) and penta-acylated (LPS1690) structures. Hitherto, the exact molecular mechanism of P. gingivalis LPS involved in periodontal pathogenesis remains unclear, due to limited understanding of the specific receptors and signaling pathways involved in LPS-host cell interactions.
  
  
  RESULTS
  This study systematically investigated the effects of P. gingivalis LPS1435/1449 and LPS1690 on the expression of TLR2 and TLR4 signal transduction and the activation of pro-inflammatory cytokines IL-6 and IL-8 in human gingival fibroblasts (HGFs). We found that LPS1435/1449 and LPS1690 differentially modulated TLR2 and TLR4 expression. NF-κB pathway was significantly activated by LPS1690 but not by LPS1435/1449. In addition, LPS1690 induced significant expression of NF-κB and p38 MPAK pathways-related genes, such as NFKBIA, NFKB1, IKBKB, MAP2K4 and MAPK8. Notably, the pro-inflammatory genes including GM-CSF, CXCL10, G-CSF, IL-6, IL-8 and CCL2 were significantly upregulated by LPS1690 while down-regulated by LPS1435/1449. Blocking assays confirmed that TLR4-mediated NF-κB signaling was vital in LPS1690-induced expression of IL-6 and IL-8 in HGFs.
  
  
  CONCLUSIONS
  The present study suggests that the tetra- and penta-acylated lipid A structures of P. gingivalis LPS differentially activate TLR4-mediated NF-κB signaling pathway, and significantly modulate the expression of IL-6 and IL-8 in HGFs. The ability to alter the lipid A structure of LPS could be one of the strategies carried-out by P. gingivalis to evade innate host defense in gingival tissues, thereby contributing to periodontal pathogenesis.
authors.affiliation: Faculty of Dentistry, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China.
authors.forename: Thanuja D K
authors.initials: TD
authors.lastname: Herath
authors.forename: Richard P
authors.initials: RP
authors.lastname: Darveau
authors.forename: Chaminda J
authors.initials: CJ
authors.lastname: Seneviratne
authors.forename: Cun-Yu
authors.initials: CY
authors.lastname: Wang
authors.forename: Yu
authors.initials: Y
authors.lastname: Wang
authors.forename: Lijian
authors.initials: L
authors.lastname: Jin
mesh_terms: D000215:Acylation; D016207:Cytokines / Q000096:biosynthesis / Q000276:immunology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000235:genetics / Q000378:metabolism*; D005347:Fibroblasts; D005881:Gingiva / Q000276:immunology / Q000378:metabolism* / Q000382:microbiology / Q000473:pathology; D006801:Humans; D008050:Lipid A / Q000737:chemistry / Q000276:immunology / Q000494:pharmacology*; D020935:MAP Kinase Signaling System / Q000187:drug effects* / Q000276:immunology; D016328:NF-kappa B / Q000276:immunology / Q000378:metabolism*; D016966:Porphyromonas gingivalis / Q000737:chemistry* / Q000276:immunology; D051197:Toll-Like Receptor 4 / Q000276:immunology / Q000378:metabolism*
chemical_list: D016207:Cytokines; D008050:Lipid A; D016328:NF-kappa B; C495345:TLR4 protein, human; D051197:Toll-Like Receptor 4; D048049:Extracellular Signal-Regulated MAP Kinases
references.citation: J Biol Chem. 1991 Oct 15;266(29):19490-8
references.pmid: 1918061
references.citation: Analyst. 2000 Apr;125(4):651-6
references.pmid: 10892021
references.citation: J Clin Periodontol. 2009 Aug;36(8):619-26
references.pmid: 19558463
references.citation: Cell Microbiol. 2007 Apr;9(4):1028-38
references.pmid: 17166236
references.citation: Clin Chim Acta. 2002 Sep;323(1-2):59-72
references.pmid: 12135807
references.citation: Nat Rev Immunol. 2003 Feb;3(2):169-76
references.pmid: 12563300
references.citation: In Vitro Cell Dev Biol Anim. 2010 Sep;46(8):718-25
references.pmid: 20607620
references.citation: Oral Microbiol Immunol. 2008 Feb;23(1):60-9
references.pmid: 18173800
references.citation: Biochem Biophys Res Commun. 2000 Jul 14;273(3):1161-7
references.pmid: 10891389
references.citation: J Immunol. 2007 Jan 15;178(2):1151-7
references.pmid: 17202379
references.citation: J Dent Res. 2006 Aug;85(8):733-8
references.pmid: 16861291
references.citation: J Periodontol. 1972 May;43(5):270-6
references.pmid: 4503430
references.citation: J Immunol. 2006 Dec 15;177(12):8296-300
references.pmid: 17142724
references.citation: Innate Immun. 2009 Dec;15(6):325-35
references.pmid: 19675119
references.citation: Infect Immun. 1998 Jul;66(7):3043-9
references.pmid: 9632564
references.citation: J Periodontal Res. 2005 Oct;40(5):407-16
references.pmid: 16105094
references.citation: Infect Immun. 1998 Apr;66(4):1660-5
references.pmid: 9529095
references.citation: J Periodontol. 2008 Jul;79(7):1241-7
references.pmid: 18597607
references.citation: Nat Immunol. 2002 Apr;3(4):354-9
references.pmid: 11912497
references.citation: J Med Microbiol. 2004 Aug;53(Pt 8):735-740
references.pmid: 15272059
references.citation: Clin Exp Immunol. 2007 Jun;148(3):529-36
references.pmid: 17335558
references.citation: Int Immunol. 2002 Nov;14(11):1325-32
references.pmid: 12407023
references.citation: Innate Immun. 2008 Apr;14(2):99-107
references.pmid: 18713726
references.citation: Infect Immun. 2000 Jun;68(6):3731-5
references.pmid: 10816537
references.citation: Infect Immun. 2011 Jan;79(1):203-10
references.pmid: 20974832
references.citation: Org Biomol Chem. 2008 Sep 21;6(18):3371-81
references.pmid: 18802645
references.citation: Infect Immun. 2004 Sep;72(9):5041-51
references.pmid: 15321997
references.citation: Nature. 2009 Apr 30;458(7242):1191-5
references.pmid: 19252480
references.citation: Infect Immun. 1995 Dec;63(12):4686-94
references.pmid: 7591124
references.citation: J Clin Periodontol. 2011 Aug;38(8):694-701
references.pmid: 21752043
references.citation: J Immunol. 2002 Apr 15;168(8):4012-7
references.pmid: 11937558
references.citation: Blood. 2000 Aug 1;96(3):1039-46
references.pmid: 10910920
references.citation: Trends Immunol. 2002 Mar;23(3):135-9
references.pmid: 11864841
references.citation: Trends Immunol. 2002 Jun;23(6):301-4
references.pmid: 12072369
references.citation: Infect Immun. 2002 Apr;70(4):1867-73
references.pmid: 11895949
references.citation: J Periodontol. 1992 Apr;63(4 Suppl):322-31
references.pmid: 1573546
references.citation: J Endod. 2011 Jun;37(6):812-8
references.pmid: 21787495
references.citation: Eur J Biochem. 2000 Apr;267(7):2008-13
references.pmid: 10727940
references.citation: Curr Pharm Des. 2007;13(36):3665-75
references.pmid: 18220804
references.citation: J Clin Invest. 2001 Jan;107(1):3-6
references.pmid: 11134170
references.citation: J Bacteriol. 2008 Apr;190(8):2920-32
references.pmid: 18263730
references.citation: Microb Pathog. 2009 Aug;47(2):68-77
references.pmid: 19460428
references.citation: J Immunol. 2010 Feb 1;184(3):1455-62
references.pmid: 20042569
references.citation: J Dent Res. 2007 Mar;86(3):249-54
references.pmid: 17314257
references.citation: Nat Rev Microbiol. 2010 Jul;8(7):481-90
references.pmid: 20514045
references.citation: Trends Microbiol. 2004 Apr;12(4):186-92
references.pmid: 15051069
references.citation: Infect Immun. 2003 Dec;71(12):6799-807
references.pmid: 14638766
references.citation: Cell Host Microbe. 2011 Oct 20;10(4):302-6
references.pmid: 22018230
references.citation: J Bacteriol. 1995 Apr;177(8):2098-106
references.pmid: 7721702
references.citation: Infect Immun. 2006 Aug;74(8):4474-85
references.pmid: 16861633
references.citation: Lancet. 2005 Nov 19;366(9499):1809-20
references.pmid: 16298220
references.citation: Cell Microbiol. 2006 May;8(5):857-68
references.pmid: 16611234
references.citation: J Immunol. 2001 Nov 1;167(9):5278-85
references.pmid: 11673543
references.citation: J Dent Res. 2005 Jul;84(7):584-95
references.pmid: 15972584
references.citation: J Dent Res. 2009 Aug;88(8):741-5
references.pmid: 19734462
references.citation: Sci Am. 1992 Aug;267(2):54-61
references.pmid: 1641625
references.citation: Microbes Infect. 2009 May-Jun;11(6-7):637-45
references.pmid: 19348960
references.citation: Carbohydr Res. 1988 Apr 15;175(2):273-82
references.pmid: 2900066
references.citation: Infect Immun. 2002 Dec;70(12):6658-64
references.pmid: 12438339
references.citation: Chem Immunol. 2000;74:5-24
references.pmid: 10608079
references.citation: FASEB J. 1994 Feb;8(2):217-25
references.pmid: 8119492
references.citation: Acta Odontol Scand. 2001 Jun;59(3):131-8
references.pmid: 11501881
references.citation: Infect Immun. 2002 Aug;70(8):4092-8
references.pmid: 12117916
references.citation: Cell Microbiol. 2006 Jan;8(1):120-9
references.pmid: 16367871
references.citation: Oral Microbiol Immunol. 2003 Feb;18(1):14-23
references.pmid: 12588454
references.citation: J Oral Biosci. 2011;53(3):233-240
references.pmid: 22162663
references.citation: J Periodontal Res. 2009 Feb;44(1):21-7
references.pmid: 19515019
references.citation: Cardiovasc Res. 2007 Jan 1;73(1):181-9
references.pmid: 17156768
references.citation: J Periodontol. 2013 Apr;84(4):535-44
references.pmid: 22680301
references.citation: Infect Immun. 2001 Mar;69(3):1477-82
references.pmid: 11179315
references.citation: Minerva Stomatol. 2003 Mar;52(3):81-7, 87-91
references.pmid: 12783061
references.citation: Infect Immun. 1987 Jan;55(1):111-7
references.pmid: 3539799
references.citation: Microbes Infect. 2002 Jul;4(8):837-51
references.pmid: 12270731
references.citation: Infect Immun. 1996 Dec;64(12):4946-51
references.pmid: 8945531
references.citation: Infect Immun. 1992 Nov;60(11):4932-7
references.pmid: 1328062
references.citation: Biochem Biophys Res Commun. 2001 Nov 9;288(4):863-7
references.pmid: 11688988
references.citation: Cell Microbiol. 2009 Nov;11(11):1587-99
references.pmid: 19552698
references.citation: Crit Rev Oral Biol Med. 2002;13(2):132-42
references.pmid: 12097356