title: DKK1 expression by synovial fibroblasts in very early rheumatoid arthritis associates with lymphocyte adhesion in an in vitro flow co-culture system.
abstract: BACKGROUND
  Synovial fibroblasts play a key role in joint destruction and regulation of the inflammatory infiltrate in established rheumatoid arthritis (RA). The mechanisms by which this occurs in the earliest stages of RA are largely unknown. We investigated the role of Dickkopf-related protein 1 (DKK1) produced by synovial fibroblasts of patients with very early rheumatoid arthritis (VeRA).
  
  
  METHODS
  Fibroblasts were isolated from the disease-modifying anti-rheumatic drug-naive Birmingham early arthritis cohort of patients with new onset of clinically apparent arthritis and inflammatory symptoms of ≤12 weeks' duration, who at follow-up had either resolving arthritis or RA. Endothelial fibroblast co-cultures were formed using porous filters, and lymphocyte adhesion to co-cultures was assessed using phase-contrast microscopy. DKK1 gene expression and secretion were quantified by quantitative polymerase chain reaction and enzyme-linked immunosorbent assay, respectively.
  
  
  RESULTS
  Synovial fibroblasts from patients with VeRA expressed significantly higher levels of DKK1 messenger RNA than those from patients with resolving arthritis. A similar trend was observed for DKK1 protein secretion. In co-culture constructs, more DKK1 tended to be secreted in co-cultures incorporating fibroblasts from VeRA than in co-cultures from non-inflamed joints and resolving arthritis. DKK1 secretion during co-culture positively correlated with lymphocyte adhesion.
  
  
  CONCLUSIONS
  Alterations in DKK1 could be involved in the pathogenesis and perpetuation of the inflammatory response in the earliest clinically apparent stages of RA.
authors.affiliation: Rheumatology Research Group, Institute of Inflammation and Ageing (IIA), University of Birmingham, Queen Elizabeth Hospital, Birmingham, B15 2WB, UK. mariajuarezp@gmail.com.
authors.forename: Maria
authors.initials: M
authors.lastname: Juarez
authors.affiliation: Rheumatology Research Group, Institute of Inflammation and Ageing (IIA), University of Birmingham, Queen Elizabeth Hospital, Birmingham, B15 2WB, UK. H.M.McGettrick@bham.ac.uk.
authors.forename: Helen M
authors.initials: HM
authors.lastname: McGettrick
authors.affiliation: Rheumatology Research Group, Institute of Inflammation and Ageing (IIA), University of Birmingham, Queen Elizabeth Hospital, Birmingham, B15 2WB, UK. D.Scheel@bham.ac.uk.
authors.forename: Dagmar
authors.initials: D
authors.lastname: Scheel-Toellner
authors.affiliation: Rheumatology Research Group, Institute of Inflammation and Ageing (IIA), University of Birmingham, Queen Elizabeth Hospital, Birmingham, B15 2WB, UK. lorraineyeo1@gmail.com.
authors.forename: Lorraine
authors.initials: L
authors.lastname: Yeo
authors.affiliation: Rheumatology Research Group, Institute of Inflammation and Ageing (IIA), University of Birmingham, Queen Elizabeth Hospital, Birmingham, B15 2WB, UK. JXS116@student.bham.ac.uk.
authors.forename: Julia
authors.initials: J
authors.lastname: Spengler
authors.affiliation: Rheumatology Research Group, Institute of Inflammation and Ageing (IIA), University of Birmingham, Queen Elizabeth Hospital, Birmingham, B15 2WB, UK. banessina@hotmail.com.
authors.forename: Banesa
authors.initials: B
authors.lastname: de Paz
authors.affiliation: Centre for Endocrinology, Diabetes and Metabolism, University of Birmingham, Birmingham, B15 2TT, UK. R.Hardy@bham.ac.uk.
authors.forename: Rowan
authors.initials: R
authors.lastname: Hardy
authors.affiliation: ANZAC Research Institute, Concord Repatriation General Hospital, Concord, NSW, 2139, Australia. mark.cooper@sydney.edu.au.
authors.forename: Mark
authors.initials: M
authors.lastname: Cooper
authors.affiliation: Rheumatology Research Group, Institute of Inflammation and Ageing (IIA), University of Birmingham, Queen Elizabeth Hospital, Birmingham, B15 2WB, UK. razak@bham.ac.uk.|Sandwell and West Birmingham Hospitals NHS Trust, Birmingham, B18 7QH, UK. razak@bham.ac.uk.
authors.forename: Karim
authors.initials: K
authors.lastname: Raza
authors.affiliation: Rheumatology Research Group, Institute of Inflammation and Ageing (IIA), University of Birmingham, Queen Elizabeth Hospital, Birmingham, B15 2WB, UK. c.d.buckley@bham.ac.uk.|Sandwell and West Birmingham Hospitals NHS Trust, Birmingham, B18 7QH, UK. c.d.buckley@bham.ac.uk.
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Buckley
authors.affiliation: Rheumatology Research Group, Institute of Inflammation and Ageing (IIA), University of Birmingham, Queen Elizabeth Hospital, Birmingham, B15 2WB, UK. a.filer@bham.ac.uk.|University Hospitals Birmingham NHS Foundation Trust, Birmingham, B15 2WB, UK. a.filer@bham.ac.uk.
authors.forename: Andrew
authors.initials: A
authors.lastname: Filer
mesh_terms: D000328:Adult; D001172:Arthritis, Rheumatoid / Q000378:metabolism* / Q000473:pathology; D002448:Cell Adhesion / Q000502:physiology; D018920:Coculture Techniques / Q000379:methods; D042241:Early Diagnosis; D005260:Female; D005347:Fibroblasts / Q000378:metabolism* / Q000473:pathology; D005500:Follow-Up Studies; D005786:Gene Expression Regulation; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000096:biosynthesis*; D008214:Lymphocytes / Q000378:metabolism* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D013583:Synovial Membrane / Q000378:metabolism* / Q000473:pathology
chemical_list: C501126:DKK1 protein, human; D036341:Intercellular Signaling Peptides and Proteins