title: Synovial fluid from patients with early osteoarthritis modulates fibroblast-like synoviocyte responses to toll-like receptor 4 and toll-like receptor 2 ligands via soluble CD14.
abstract: OBJECTIVE
  Synovial inflammation, a feature of both osteoarthritis (OA) and meniscal injury, is hypothesized to be triggered in part via stimulation of Toll-like receptors (TLRs). We undertook this study to test whether a TLR-2- or TLR-4-stimulating factor in synovial fluid (SF) from patients with early knee OA with meniscal injury could lead to inflammatory activation of synoviocytes.
  
  
  METHODS
  SF was obtained from patients with early OA cartilage damage undergoing arthroscopic meniscal procedures. SF was used to stimulate primary cultures of fibroblast-like synoviocytes (FLS) and cell lines transfected with TLR-2 or TLR-4. SF was used either alone or in combination with a TLR-2 stimulus (palmitoyl-3-cysteine-serine-lysine-4 [Pam3CSK4]) or a TLR-4 stimulus (lipopolysaccharide [LPS]). In blocking experiments, SF was preincubated with anti-CD14 antibody.
  
  
  RESULTS
  SF from these patients did not stimulate interleukin-8 (IL-8) release from TLR transfectants. Compared with SF on its own, SF (at concentrations of 0.09-25%) in combination with TLR-2 or TLR-4 ligands resulted in significant augmentation of IL-8 release from both transfectants and primary FLS. Soluble CD14 (sCD14), a coreceptor for TLRs, was measured in SF from patients with early OA at levels comparable to those in patients with advanced OA and patients with rheumatoid arthritis. Blockade with anti-CD14 antibody abolished the ability of SF to augment IL-8 production in response to LPS, and diminished Pam3CSK4 responses.
  
  
  CONCLUSIONS
  SF augments FLS responses to TLR-2 and TLR-4 ligands. This effect was largely due to sCD14. Our results demonstrate that sCD14 in the setting of OA and meniscal injury sensitizes FLS to respond to inflammatory stimuli such as TLR ligands.
authors.affiliation: Rush University Medical Center, Chicago, Illinois 60612, USA.
authors.forename: Anjali
authors.initials: A
authors.lastname: Nair
authors.forename: Veero
authors.initials: V
authors.lastname: Kanda
authors.forename: Charles
authors.initials: C
authors.lastname: Bush-Joseph
authors.forename: Nikhil
authors.initials: N
authors.lastname: Verma
authors.forename: Susan
authors.initials: S
authors.lastname: Chubinskaya
authors.forename: Katalin
authors.initials: K
authors.lastname: Mikecz
authors.forename: Tibor T
authors.initials: TT
authors.lastname: Glant
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Malfait
authors.forename: Mary K
authors.initials: MK
authors.lastname: Crow
authors.forename: Greg T
authors.initials: GT
authors.lastname: Spear
authors.forename: Alison
authors.initials: A
authors.lastname: Finnegan
authors.forename: Carla R
authors.initials: CR
authors.lastname: Scanzello
mesh_terms: D000368:Aged; D001172:Arthritis, Rheumatoid / Q000378:metabolism / Q000473:pathology; D005260:Female; D006801:Humans; D055666:Lipopeptides / Q000494:pharmacology; D018950:Lipopolysaccharide Receptors / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000378:metabolism* / Q000473:pathology; D013582:Synovial Fluid / Q000187:drug effects / Q000378:metabolism*; D013583:Synovial Membrane / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D051195:Toll-Like Receptor 2 / Q000819:agonists / Q000378:metabolism*; D051197:Toll-Like Receptor 4 / Q000819:agonists / Q000378:metabolism*
chemical_list: D055666:Lipopeptides; D018950:Lipopolysaccharide Receptors; D008070:Lipopolysaccharides; C508075:Pam(3)CSK(4) peptide; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4