title: Galectin 3 induces a distinctive pattern of cytokine and chemokine production in rheumatoid synovial fibroblasts via selective signaling pathways.
abstract: OBJECTIVE
  High expression of galectin 3 at sites of joint destruction in rheumatoid arthritis (RA) suggests that galectin 3 plays a role in RA pathogenesis. Previous studies have demonstrated the effects of galectins on immune cells, such as lymphocytes and macrophages. This study was undertaken to investigate the hypothesis that galectin 3 induces proinflammatory effects in RA by modulating the pattern of cytokine and chemokine production in synovial fibroblasts.
  
  
  METHODS
  Matched samples of RA synovial and skin fibroblasts were pretreated with galectin 3 or tumor necrosis factor alpha (TNFalpha), and the levels of a panel of cytokines, chemokines, and matrix metalloproteinases (MMPs) were determined using enzyme-linked immunosorbent assays and multiplex assays. Specific inhibitors were used to dissect signaling pathways, which were confirmed by Western blotting and NF-kappaB activation assay.
  
  
  RESULTS
  Galectin 3 induced secretion of interleukin-6 (IL-6), granulocyte-macrophage colony-stimulating factor, CXCL8, and MMP-3 in both synovial and skin fibroblasts. By contrast, galectin 3-induced secretion of TNFalpha, CCL2, CCL3, and CCL5 was significantly greater in synovial fibroblasts than in skin fibroblasts. TNFalpha blockade ruled out autocrine TNFalpha-stimulated induction of chemokines. The MAPKs p38, JNK, and ERK were necessary for IL-6 production, but phosphatidylinositol 3-kinase (PI 3-kinase) was required for selective CCL5 induction. NF-kappaB activation was required for production of both IL-6 and CCL5.
  
  
  CONCLUSIONS
  Our findings indicate that galectin 3 promotes proinflammatory cytokine secretion by tissue fibroblasts. However, galectin 3 induces the production of mononuclear cell-recruiting chemokines uniquely from synovial fibroblasts, but not matched skin fibroblasts, via a PI 3-kinase signaling pathway. These data provide further evidence of the role of synovial fibroblasts in regulating the pattern and persistence of the inflammatory infiltrate in RA and suggest a new and important functional consequence of the observed high expression of galectin 3 in the rheumatoid synovium.
authors.affiliation: University of Birmingham, Division of Immunity and Infection, Birmingham, UK. a.filer@bham.ac.uk
authors.forename: Andrew
authors.initials: A
authors.lastname: Filer
authors.forename: Magdalena
authors.initials: M
authors.lastname: Bik
authors.forename: Greg N
authors.initials: GN
authors.lastname: Parsonage
authors.forename: John
authors.initials: J
authors.lastname: Fitton
authors.forename: Emily
authors.initials: E
authors.lastname: Trebilcock
authors.forename: Katherine
authors.initials: K
authors.lastname: Howlett
authors.forename: Michelle
authors.initials: M
authors.lastname: Cook
authors.forename: Karim
authors.initials: K
authors.lastname: Raza
authors.forename: David L
authors.initials: DL
authors.lastname: Simmons
authors.forename: Andrew M C
authors.initials: AM
authors.lastname: Thomas
authors.forename: Mike
authors.initials: M
authors.lastname: Salmon
authors.forename: Dagmar
authors.initials: D
authors.lastname: Scheel-Toellner
authors.forename: Janet M
authors.initials: JM
authors.lastname: Lord
authors.forename: Gabriel A
authors.initials: GA
authors.lastname: Rabinovich
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Buckley
mesh_terms: D001172:Arthritis, Rheumatoid / Q000378:metabolism* / Q000473:pathology; D002478:Cells, Cultured; D018932:Chemokine CCL2 / Q000378:metabolism; D054405:Chemokine CCL3 / Q000378:metabolism; D018946:Chemokine CCL5 / Q000378:metabolism; D018925:Chemokines / Q000378:metabolism*; D016207:Cytokines / Q000378:metabolism*; D005347:Fibroblasts / Q000378:metabolism* / Q000473:pathology; D037502:Galectin 3 / Q000502:physiology*; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000378:metabolism; D006801:Humans; D015850:Interleukin-6 / Q000378:metabolism; D016209:Interleukin-8 / Q000378:metabolism; D019278:Matrix Metalloproteinase 3 / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D012867:Skin / Q000166:cytology / Q000378:metabolism; D013583:Synovial Membrane / Q000378:metabolism* / Q000473:pathology; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism / Q000494:pharmacology
chemical_list: D018932:Chemokine CCL2; D054405:Chemokine CCL3; D018946:Chemokine CCL5; D018925:Chemokines; D016207:Cytokines; D037502:Galectin 3; D015850:Interleukin-6; D016209:Interleukin-8; D014409:Tumor Necrosis Factor-alpha; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D019869:Phosphatidylinositol 3-Kinases; D019278:Matrix Metalloproteinase 3