title: GDF-5 is suppressed by IL-1beta and enhances TGF-beta3-mediated chondrogenic differentiation in human rheumatoid fibroblast-like synoviocytes.
abstract: OBJECTIVE
  To investigate the expression of growth differentiation factor-5 (GDF-5) in chondrocytes (HC) and fibroblast-like synoviocytes (FLS) from humans with rheumatoid arthritis (RA) when stimulated with proinflammatory cytokines and to explore whether GDF-5 plays a role in regulating the differentiation of FLS-RA into chondrocytes.
  
  
  METHODS
  Expression of GDF-5 in synovium and cartilage in RA and osteoarthritis (OA) was assessed by immunohistochemistry. GDF-5 production in FLS-RA and HC-RA was examined through real-time quantitative RT-PCR (Q-PCR) and western blotting. Expressions of GDF-associated receptors on FLS-RA were determined by semiquantitative-PCR, and MTT assay was used to study the effects on FLS-RA proliferation. Effect of GDF-5 and TGF-beta3 on in vitro chondrogenic ability of FLS-RA was investigated using pellet-culture system, Q-PCR and histological analysis.
  
  
  RESULTS
  Immunohistochemical analysis demonstrated that GDF-5 expression in the synovium and cartilage from joints of RA patients was much lower than that of OA patients. Addition of IL-1beta or TNF-alpha appeared to downregulate the expression of GDF-5 in HC-RA and FLS-RA. Inhibition of GDF-5 expression by IL-1beta in RA-FLS was attenuated by pretreatment with MEK1/2 inhibitor. GDF-5-associated receptors were expressed in FLS-RA, but GDF-5 had no effect on FLS-RA proliferation. GDF-5 had a strong chondrogenic-promoting effect on TGF-beta3-induced chondrocyte differentiation in FLS-RA.
  
  
  CONCLUSIONS
  GDF-5 is expressed in FLS-RA and HC-RA, and its expression is strongly downregulated by proinflammatory cytokines. MEK-ERK pathway is a negative regulator of GDF-5 expression in FLS-RA. In FLS-RA, synergy between GDF-5 and TGF-beta3 enhances chondrogenesis. Anti-inflammatory drugs combined with GDF-5 might be a new therapeutic treatment for RA.
authors.affiliation: Graduate Institute of Medical Sciences, National Defense Medical Center, Taiwan, Republic of China.
authors.forename: Fei-Lan
authors.initials: FL
authors.lastname: Liu
authors.forename: Li-Hsiang
authors.initials: LH
authors.lastname: Lin
authors.forename: Huey-Kang
authors.initials: HK
authors.lastname: Sytwu
authors.forename: Deh-Ming
authors.initials: DM
authors.lastname: Chang
mesh_terms: D001172:Arthritis, Rheumatoid / Q000378:metabolism* / Q000473:pathology; D002358:Cartilage, Articular / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D002454:Cell Differentiation / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D019902:Chondrocytes / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D015536:Down-Regulation / Q000187:drug effects / Q000235:genetics; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D005786:Gene Expression Regulation / Q000187:drug effects; D055428:Growth Differentiation Factor 5 / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D007124:Immunoenzyme Techniques; D053583:Interleukin-1beta / Q000494:pharmacology*; D010003:Osteoarthritis / Q000378:metabolism* / Q000473:pathology; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013583:Synovial Membrane / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D053782:Transforming Growth Factor beta3 / Q000235:genetics / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
chemical_list: D055428:Growth Differentiation Factor 5; D053583:Interleukin-1beta; D012333:RNA, Messenger; D053782:Transforming Growth Factor beta3; D014409:Tumor Necrosis Factor-alpha