title: Expression and regulation of toll-like receptors (TLRs) in human intervertebral disc cells.
abstract: OBJECTIVE
  Although inflammatory processes play an essential role in painful intervertebral disc (IVD) degeneration, the underlying regulatory mechanisms are not well understood. This study was designed to investigate the expression, regulation and importance of specific toll-like receptors (TLRs)--which have been shown to play an essential role e.g. in osteoarthritis--during degenerative disc disease.
  
  
  METHODS
  The expression of TLRs in human IVDs was measured in isolated cells as well as in normal or degenerated IVD tissue. The role of IL-1β or TNF-α in regulating TLRs (expression/activation) as well as in regulating activity of down-stream pathways (NF-κB) and expression of inflammation-related genes (IL-6, IL-8, HSP60, HSP70, HMGB1) was analyzed.
  
  
  RESULTS
  Expression of TLR1/2/3/4/5/6/9/10 was detected in isolated human IVD cells, with TLR1/2/4/6 being dependent on the degree of IVD degeneration. Stimulation with IL-1β or TNF-α moderately increased TLR1/TLR4 mRNA expression (TNF-α only), and strongly increased TLR2 mRNA expression (IL-1β/TNF-α), with the latter being confirmed on the protein level. Stimulation with IL-1β, TNF-α or Pam3CSK4 (a TLR2-ligand) stimulated IL-6 and IL-8, which was inhibited by a TLR2 neutralizing antibody for Pam3CSK4; IL-1β and TNF-α caused NF-κB activation. HSP60, HSP70 and HMGB1 did not increase IL-6 or IL-8 and were not regulated by IL-1β/TNF-α.
  
  
  CONCLUSIONS
  We provide evidence that several TLRs are expressed in human IVD cells, with TLR2 possibly playing the most crucial role. As TLRs mediate catabolic and inflammatory processes, increased levels of TLRs may lead to aggravated disc degeneration, chronic inflammation and pain development. Especially with the identification of more endogenous TLR ligands, targeting these receptors may hold therapeutic promise.
authors.affiliation: Competence Center for Applied Biotechnology and Molecular Medicine, University of Zurich, Zurich, Switzerland, marina.klawitter@cabmm.uzh.ch.
authors.forename: Marina
authors.initials: M
authors.lastname: Klawitter
authors.forename: Michiyuki
authors.initials: M
authors.lastname: Hakozaki
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kobayashi
authors.forename: Olga
authors.initials: O
authors.lastname: Krupkova
authors.forename: Lilian
authors.initials: L
authors.lastname: Quero
authors.forename: Caroline
authors.initials: C
authors.lastname: Ospelt
authors.forename: Steffen
authors.initials: S
authors.lastname: Gay
authors.forename: Oliver
authors.initials: O
authors.lastname: Hausmann
authors.forename: Thomas
authors.initials: T
authors.lastname: Liebscher
authors.forename: Ullrich
authors.initials: U
authors.lastname: Meier
authors.forename: Miho
authors.initials: M
authors.lastname: Sekiguchi
authors.forename: Shin-ichi
authors.initials: S
authors.lastname: Konno
authors.forename: Norbert
authors.initials: N
authors.lastname: Boos
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Ferguson
authors.forename: Karin
authors.initials: K
authors.lastname: Wuertz
mesh_terms: D002478:Cells, Cultured; D018834:Chaperonin 60 / Q000235:genetics; D005786:Gene Expression Regulation / Q000187:drug effects / Q000276:immunology; D024243:HMGB1 Protein / Q000235:genetics; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics; D006801:Humans; D018836:Inflammation Mediators / Q000494:pharmacology; D053583:Interleukin-1beta / Q000494:pharmacology; D015850:Interleukin-6 / Q000235:genetics; D016209:Interleukin-8 / Q000235:genetics; D007403:Intervertebral Disc / Q000166:cytology / Q000276:immunology* / Q000502:physiology*; D055959:Intervertebral Disc Degeneration / Q000235:genetics* / Q000276:immunology* / Q000473:pathology; D055666:Lipopeptides / Q000494:pharmacology; D024101:Mitochondrial Proteins / Q000235:genetics; D016328:NF-kappa B / Q000235:genetics; D010003:Osteoarthritis / Q000276:immunology / Q000473:pathology / Q000503:physiopathology; D051193:Toll-Like Receptors / Q000235:genetics* / Q000276:immunology*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
chemical_list: C508606:CXCL8 protein, human; D018834:Chaperonin 60; D024243:HMGB1 Protein; C585491:HMGB1 protein, human; D018840:HSP70 Heat-Shock Proteins; C060293:HSPD1 protein, human; C508600:IL6 protein, human; D018836:Inflammation Mediators; D053583:Interleukin-1beta; D015850:Interleukin-6; D016209:Interleukin-8; D055666:Lipopeptides; D024101:Mitochondrial Proteins; D016328:NF-kappa B; C508075:Pam(3)CSK(4) peptide; D051193:Toll-Like Receptors; D014409:Tumor Necrosis Factor-alpha