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Attachment to laminin-111 facilitates transforming growth factor β-induced expression of matrix metalloproteinase-3 in synovial fibroblasts
  1. Maik Hoberg1,
  2. Maximilian Rudert1,
  3. Thomas Pap2,
  4. Gerd Klein3,
  5. Steffen Gay4,
  6. Wilhelm K Aicher5
  1. 1Department of Orthopedic Surgery, CRONA University Hospital, Tübingen, Germany
  2. 2Division of Molecular Medicine of Musculoskeletal Tissue, Department of Orthopedics, Münster University Hospital, Münster, Germany
  3. 3Center for Medical Research (ZMF), Section for Transplantation Immunology, University of Tübingen, Tübingen, Germany
  4. 4WHO Center for Exp. Rheumatology, University Hospital Zürich, and Zürich Center for Integrative Human Physiology (ZIHP), Zürich, Switzerland
  5. 5Center for Medical Research (ZMF), Department of Orthopaedic Surgery, Eberhard-Karls-University Medical School, Tübingen, Germany
  1. Correspondence to:
    W K Aicher
    ZMF, Center for Medical Research, Eberhard-Karls-University Medical School, Waldhoernle Strasse 22, D 72072 Tuebingen, Germany; aicher{at}


Background: In the synovial membrane of patients with rheumatoid arthritis (RA), a strong expression of laminins and matrix degrading proteases was reported.

Aim: To investigate the regulation of matrix metalloproteinases (MMPs) in synovial fibroblasts (SFs) of patients with osteoarthritis (OA) and RA by attachment to laminin-1 (LM-111) and in the presence or absence of costimulatory signals provided by transforming growth factor β (TGFβ).

Methods: SFs were seeded in laminin-coated flasks and activated by addition of TGFβ. The expression of genes was investigated by quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR), immunocytochemistry and ELISA, and intracellular signalling pathways by immunoblotting, and by poisoning p38MAPK by SB203580, MEK-ERK by PD98059 and SMAD2 by A-83-01.

Results: Attachment of SF to LM-111 did not activate the expression of MMPs, but addition of TGFβ induced a fivefold higher expression of MMP-3. Incubation of SF on LM-111 in the presence of TGFβ induced a significant 12-fold higher expression of MMP-3 mRNA, and secretion of MMP-3 was elevated 20-fold above controls. Functional blocking of LM-111–integrin interaction reduced the laminin-activated MMP-3 expression significantly. Stimulation of SF by LM-111 and TGFβ activated the p38MAPK, ERK and SMAD2 pathways, and inhibition of these pathways by using SB203580, PD98059 or A-83-01 confirmed the involvement of these pathways in the regulation of MMP-3.

Conclusion: Attachment of SF to LM-111 by itself has only minor effects on the expression of MMP-1 or MMP-3, but it facilitates the TGFβ-induced expression of MMP-3 significantly. This mode of MMP-3 induction may therefore contribute to inflammatory joint destruction in RA independent of the proinflammatory cytokines interleukin (IL)1β or tumour necrosis factor (TNF)α.

  • JNK, jun-N kinase-1
  • LM, laminin
  • mAb, monoclonal antibody
  • MAP, mitogen-activated protein
  • MMP, matrix metalloproteinase
  • OA, osteoarthritis
  • qRT-PCR, quantitative reverse transcriptase-polymerase chain reaction
  • RA, rheumatoid arthritis
  • SAPK, stress-activated protein kinase
  • SF, synovial fibroblast
  • SMAD, transcription factor (homologue to mothers against DPP and SMA genes)
  • TGF, transforming growth factor
  • TIMP, tissue inhibitor of metalloproteinase
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  • Published Online First 23 November 2006

  • Funding: This project was supported by DFG-grants Ai16/10-2 and Ai16/14-1 to WKA and in part by institutional funding. SG was supported by the European Community’s FP6 funding. This publication reflects only the authors’ views. The European Community is not liable for any use that may be made of the information herein. There are no disclosures for this study by any of the authors.

  • Competing interests: None declared.

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