title: Bacterial lipopolysaccharides form procollagen-endotoxin complexes that trigger cartilage inflammation and degeneration: implications for the development of rheumatoid arthritis.
abstract: BACKGROUND
  We have previously reported that bacterial toxins, especially endotoxins such as lipopolysaccharides (LPS), might be important causative agents in the pathogenesis of rheumatoid arthritis (RA) in an in vitro model that simulates the potential effects of residing in damp buildings. Since numerous inflammatory processes are linked with the nuclear factor-κB (NF-κB), we investigated in detail the effects of LPS on the NF-κB pathway and the postulated formation of procollagen-endotoxin complexes.
  
  
  METHODS
  An in vitro model of human chondrocytes was used to investigate LPS-mediated inflammatory signaling.
  
  
  RESULTS
  Immunoelectron microscopy revealed that LPS physically interact with collagen type II in the extracellular matrix (ECM) and anti-collagen type II significantly reduced this interaction. BMS-345541 (a specific inhibitor of IκB kinase (IKK)) or wortmannin (a specific inhibitor of phosphatidylinositol 3-kinase (PI-3K)) inhibited the LPS-induced degradation of the ECM and apoptosis in chondrocytes. This effect was completely inhibited by combining BMS-345541 and wortmannin. Furthermore, BMS-345541 and/or wortmannin suppressed the LPS-induced upregulation of catabolic enzymes that mediate ECM degradation (matrix metalloproteinases-9, -13), cyclooxygenase-2 and apoptosis (activated caspase-3). These proteins are regulated by NF-κB, suggesting that the NF-κB and PI-3K pathways are involved in LPS-induced cartilage degradation. The induction of NF-κB correlated with activation of IκBα kinase, IκBα phosphorylation, IκBα degradation, p65 phosphorylation and p65 nuclear translocation. Further upstream, LPS induced the expression of Toll-like receptor 4 (TLR4) and bound with TLR4, indicating that LPS acts through TLR4.
  
  
  CONCLUSIONS
  These results suggest that molecular associations between LPS/TLR4/collagen type II in chondrocytes upregulate the NF-κB and PI-3K signaling pathways and activate proinflammatory activity.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Lorenz
authors.forename: Constanze
authors.initials: C
authors.lastname: Buhrmann
authors.forename: Ali
authors.initials: A
authors.lastname: Mobasheri
authors.forename: Cora
authors.initials: C
authors.lastname: Lueders
authors.forename: Mehdi
authors.initials: M
authors.lastname: Shakibaei
mesh_terms: D000730:Androstadienes / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D001172:Arthritis, Rheumatoid / Q000378:metabolism; D001427:Bacterial Toxins / Q000378:metabolism*; D002356:Cartilage / Q000378:metabolism* / Q000473:pathology; D053148:Caspase 3 / Q000378:metabolism; D002478:Cells, Cultured; D019902:Chondrocytes / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D051546:Cyclooxygenase 2 / Q000378:metabolism; D005109:Extracellular Matrix / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D051550:I-kappa B Kinase / Q000037:antagonists & inhibitors / Q000378:metabolism; D007093:Imidazoles / Q000494:pharmacology; D015151:Immunoblotting; D008070:Lipopolysaccharides / Q000378:metabolism* / Q000494:pharmacology; D020782:Matrix Metalloproteinases / Q000378:metabolism; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D016328:NF-kappa B / Q000378:metabolism; D010007:Osteochondritis / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation / Q000187:drug effects; D011347:Procollagen / Q000378:metabolism*; D011810:Quinoxalines / Q000494:pharmacology; D051197:Toll-Like Receptor 4 / Q000378:metabolism; D000077191:Wortmannin
chemical_list: D000730:Androstadienes; D001427:Bacterial Toxins; D053148:Caspase 3; D051546:Cyclooxygenase 2; D051550:I-kappa B Kinase; D007093:Imidazoles; D008070:Lipopolysaccharides; D020782:Matrix Metalloproteinases; D016328:NF-kappa B; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011347:Procollagen; D011810:Quinoxalines; D051197:Toll-Like Receptor 4; D000077191:Wortmannin; C471109:4(2'-aminoethyl)amino-1,8-dimethylimidazo(1,2-a)quinoxaline; C496540:PTGS2 protein, human
references.citation: Biochem Pharmacol. 2008 Dec 1;76(11):1426-39
references.pmid: 18606398
references.citation: Histol Histopathol. 1993 Oct;8(4):715-23
references.pmid: 8305821
references.citation: J Immunol. 2000 Feb 1;164(3):1355-63
references.pmid: 10640750
references.citation: J Histochem Cytochem. 1995 Oct;43(10):1061-9
references.pmid: 7560884
references.citation: J Immunol. 2007 Nov 1;179(9):6246-54
references.pmid: 17947700
references.citation: J Mol Med (Berl). 2004 Jul;82(7):434-48
references.pmid: 15175863
references.citation: Mol Cancer Res. 2008 Jun;6(6):1059-70
references.pmid: 18567808
references.citation: J Biol Chem. 2000 Aug 11;275(32):24255-63
references.pmid: 10823826
references.citation: Nature. 1995 Aug 17;376(6541):599-602
references.pmid: 7637810
references.citation: Curr Biol. 1999 Jun 3;9(11):601-4
references.pmid: 10359702
references.citation: Connect Tissue Res. 1999;40(1):1-11
references.pmid: 10770646
references.citation: Innate Immun. 2008 Aug;14(4):233-46
references.pmid: 18669609
references.citation: J Biol Chem. 2003 Jan 17;278(3):1450-6
references.pmid: 12403772
references.citation: Biochimie. 2010 Feb;92(2):204-15
references.pmid: 19879319
references.citation: Arthritis Rheum. 1997 Apr;40(4):598-609
references.pmid: 9125240
references.citation: N Engl J Med. 1997 Apr 10;336(15):1066-71
references.pmid: 9091804
references.citation: Curr Opin Immunol. 2002 Feb;14(1):123-8
references.pmid: 11790542
references.citation: Nature. 2003 May 15;423(6937):356-61
references.pmid: 12748655
references.citation: Arthritis Res Ther. 2009;11(6):R165
references.pmid: 19889203
references.citation: Osteoarthritis Cartilage. 2012 Dec;20(12):1583-90
references.pmid: 22917743
references.citation: Clin Rev Allergy Immunol. 2010 Aug;39(1):10-9
references.pmid: 19707891
references.citation: J Invest Dermatol. 2010 Aug;130(8):2110-9
references.pmid: 20393484
references.citation: Indoor Air. 2000 Sep;10(3):138-45
references.pmid: 10979195
references.citation: J Leukoc Biol. 2002 Oct;72(4):711-7
references.pmid: 12377940
references.citation: Biochem Pharmacol. 2007 May 1;73(9):1434-45
references.pmid: 17291458
references.citation: J Biol Chem. 1997 Nov 14;272(46):29167-73
references.pmid: 9360994
references.citation: Arthritis Rheum. 2008 Oct;58(10):2936-48
references.pmid: 18821703
references.citation: Eur Respir J. 2001 Dec;18(6):951-8
references.pmid: 11829101
references.citation: J Biol Chem. 2012 Nov 2;287(45):38050-63
references.pmid: 22936809
references.citation: Biochem J. 1999 Sep 15;342 Pt 3:615-23
references.pmid: 10477272
references.citation: Curr Pharm Des. 2005;11(5):581-611
references.pmid: 15720277
references.citation: J Exp Med. 1999 Jun 7;189(11):1777-82
references.pmid: 10359581
references.citation: Springer Semin Immunopathol. 2003 Aug;25(1):3-18
references.pmid: 12904888
references.citation: Arthritis Rheum. 2001 Oct;44(10):2218-20
references.pmid: 11665960
references.citation: Clin Sci (Lond). 2012 Dec;123(11):627-34
references.pmid: 22888972
references.citation: Nature. 1999 Nov 18;402(6759):304-9
references.pmid: 10580503
references.citation: Am J Physiol Endocrinol Metab. 2007 Mar;292(3):E740-7
references.pmid: 17090751
references.citation: Am J Physiol. 1998 Jun;274(6):R1594-603
references.pmid: 9608013
references.citation: J Biol Chem. 2011 Aug 12;286(32):28556-66
references.pmid: 21669872
references.citation: J Cell Biochem. 2009 Jan 1;106(1):83-92
references.pmid: 19009563
references.citation: FASEB J. 2003 Nov;17(14):1986-95
references.pmid: 14597668
references.citation: Nature. 1999 Sep 2;401(6748):86-90
references.pmid: 10485711
references.citation: Cell. 2002 Apr;109 Suppl:S81-96
references.pmid: 11983155
references.citation: Best Pract Res Clin Rheumatol. 2008 Apr;22(2):239-52
references.pmid: 18455682
references.citation: Annu Rev Immunol. 2001;19:163-96
references.pmid: 11244034
references.citation: Proc Natl Acad Sci U S A. 2012 Jan 3;109(1):267-72
references.pmid: 22187458
references.citation: J Biol Chem. 2001 Jul 20;276(29):27740-4
references.pmid: 11356844
references.citation: Exp Cell Res. 1998 Apr 10;240(1):95-106
references.pmid: 9570925
references.citation: Innate Immun. 2010 Feb;16(1):48-63
references.pmid: 19710088
references.citation: J Inflamm. 1995-1996;47(1-2):90-6
references.pmid: 8913935
references.citation: Arthritis Rheum. 1996 Apr;39(4):583-91
references.pmid: 8630106
references.citation: Arthritis Rheum. 2006 Jul;54(7):2152-63
references.pmid: 16802353
references.citation: Annu Rev Immunol. 1995;13:437-57
references.pmid: 7542010
references.citation: Rheumatol Int. 2006 May;26(7):641-54
references.pmid: 16362367
references.citation: Immunol Today. 1997 Jul;18(7):329-34
references.pmid: 9238836
references.citation: Trends Genet. 2004 Jan;20(1):33-43
references.pmid: 14698617
references.citation: J Clin Invest. 1976 May;57(5):1148-57
references.pmid: 1262462
references.citation: J Biol Chem. 2001 Apr 20;276(16):13289-94
references.pmid: 11278768
references.citation: Arch Biochem Biophys. 2009 Nov;491(1-2):7-15
references.pmid: 19800307
references.citation: Inflamm Allergy Drug Targets. 2008 Mar;7(1):53-66
references.pmid: 18473901
references.citation: N Engl J Med. 2007 Jun 7;356(23):2419-20
references.pmid: 17554126
references.citation: Arthritis Rheum. 2003 May;48(5):1249-60
references.pmid: 12746898