title: Effects of inflammatory cytokine IL-27 on the activation of fibroblast-like synoviocytes in rheumatoid arthritis.
abstract: BACKGROUND
  Interleukin (IL)-27 is a novel member of the IL-6/IL-12 family cytokines that are produced early by antigen-presenting cells in T helper (Th)1-mediated inflammation. Elevated expression of IL-27 has been detected in the synovial membranes and fluid of rheumatoid arthritis (RA).
  
  
  METHODS
  We investigated the in vitro effects of IL-27, alone or in combination with inflammatory cytokine tumor necrosis factor (TNF)-α or IL-1 β on the pro-inflammatory activation of human primary fibroblast-like synoviocytes (FLS) from RA patients and normal control subjects, and the underlying intracellular signaling molecules were determined by intracellular staining using flow cytometry.
  
  
  RESULTS
  Significantly higher plasma concentration of IL-27 was found in RA patients (n = 112) than control subjects (n = 46). Both control and RA-FLS constitutively express functional IL-27 receptor heterodimer, gp130 and WSX-1, with more potent IL-27-mediated activation of signal transducers and activators of transcription (STAT)1 in RA-FLS. IL-27 was found to induce significantly higher cell surface expression of intercellular adhesion molecule (ICAM)-1 and vascular cell adhesion molecule (VCAM)-1 and release of inflammatory chemokine IL-6, CCL2, CXCL9, CXCL10 and matrix metalloproteinase-1 of RA-FLS than that of control FLS (all P < 0.05). Moreover, an additive or synergistic effect was observed in the combined treatment of IL-27 and TNF-α or IL-1 β on the surface expression of ICAM-1 and VCAM-1 and the release of CXCL9 and CXCL10 of RA-FLS. Further investigations showed that the expression of ICAM-1, VCAM-1 and chemokines stimulated by IL-27 was differentially regulated by intracellular activation of phosphatidylinositol 3-OH kinase-AKT, c-Jun amino-terminal kinase and Janus kinase pathways.
  
  
  CONCLUSIONS
  Our results therefore provide a new insight into the IL-27-activated immunopathological mechanisms mediated by distinct intracellular signal transductions in joint inflammation of RA.
authors.affiliation: Department of Chemical Pathology, The Chinese University of Hong Kong, Shatin, NT, Hong Kong. ck-wong@cuhk.edu.hk
authors.forename: Chun K
authors.initials: CK
authors.lastname: Wong
authors.forename: Da P
authors.initials: DP
authors.lastname: Chen
authors.forename: Lai S
authors.initials: LS
authors.lastname: Tam
authors.forename: Edmund K
authors.initials: EK
authors.lastname: Li
authors.forename: Yi B
authors.initials: YB
authors.lastname: Yin
authors.forename: Christopher W K
authors.initials: CW
authors.lastname: Lam
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001172:Arthritis, Rheumatoid / Q000276:immunology* / Q000473:pathology; D002478:Cells, Cultured; D050822:Cytokine Receptor gp130 / Q000235:genetics / Q000276:immunology; D005260:Female; D005347:Fibroblasts / Q000187:drug effects / Q000276:immunology* / Q000473:pathology; D005434:Flow Cytometry; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D053583:Interleukin-1beta / Q000276:immunology / Q000378:metabolism / Q000494:pharmacology; D007378:Interleukins / Q000097:blood / Q000276:immunology* / Q000494:pharmacology; D008297:Male; D008875:Middle Aged; D012333:RNA, Messenger / Q000378:metabolism; D018123:Receptors, Interleukin / Q000235:genetics / Q000276:immunology; D015398:Signal Transduction / Q000276:immunology; D013583:Synovial Membrane / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology / Q000378:metabolism / Q000494:pharmacology; D019010:Vascular Cell Adhesion Molecule-1 / Q000378:metabolism
chemical_list: C112441:IL27RA protein, human; D053583:Interleukin-1beta; D007378:Interleukins; C464565:MYDGF protein, human; D012333:RNA, Messenger; D018123:Receptors, Interleukin; D014409:Tumor Necrosis Factor-alpha; D019010:Vascular Cell Adhesion Molecule-1; D018799:Intercellular Adhesion Molecule-1; D050822:Cytokine Receptor gp130