The interleukin-1 receptor in normal and osteoarthritic human articular chondrocytes. Identification as the type I receptor and analysis of binding kinetics and biologic function

Authors

  • Johanne Martel-Pelletier PhD,

    Associate Professor of Medicine
    1. Rheumatic Disease Unit Research Laboratory, and the Allergy Research Laboratory, Notre-Dame Hospital Research Center, Montreal, Quebec, Canada, affiliated with the Department of Medicine, University of Montreal, and the Department of Biochemistry and Molecular Biology, Merck Sharp and Dohme Research Laboratories, Rahway, New Jersey.
    Search for more papers by this author
  • Robert Mccollum MSc,

    Research Assistant
    1. Rheumatic Disease Unit Research Laboratory, and the Allergy Research Laboratory, Notre-Dame Hospital Research Center, Montreal, Quebec, Canada, affiliated with the Department of Medicine, University of Montreal, and the Department of Biochemistry and Molecular Biology, Merck Sharp and Dohme Research Laboratories, Rahway, New Jersey.
    Search for more papers by this author
  • John Dibattista PhD,

    Fellow
    1. Rheumatic Disease Unit Research Laboratory, and the Allergy Research Laboratory, Notre-Dame Hospital Research Center, Montreal, Quebec, Canada, affiliated with the Department of Medicine, University of Montreal, and the Department of Biochemistry and Molecular Biology, Merck Sharp and Dohme Research Laboratories, Rahway, New Jersey.
    Search for more papers by this author
  • Marie-Pierre Faure MSc,

    Research Assistant
    1. Rheumatic Disease Unit Research Laboratory, and the Allergy Research Laboratory, Notre-Dame Hospital Research Center, Montreal, Quebec, Canada, affiliated with the Department of Medicine, University of Montreal, and the Department of Biochemistry and Molecular Biology, Merck Sharp and Dohme Research Laboratories, Rahway, New Jersey.
    Search for more papers by this author
  • Jayne A. Chin PhD,

    Research Scientist
    1. Rheumatic Disease Unit Research Laboratory, and the Allergy Research Laboratory, Notre-Dame Hospital Research Center, Montreal, Quebec, Canada, affiliated with the Department of Medicine, University of Montreal, and the Department of Biochemistry and Molecular Biology, Merck Sharp and Dohme Research Laboratories, Rahway, New Jersey.
    Search for more papers by this author
  • Sylvie Fournier MSc,

    student Allergy Research Laboratory
    1. Rheumatic Disease Unit Research Laboratory, and the Allergy Research Laboratory, Notre-Dame Hospital Research Center, Montreal, Quebec, Canada, affiliated with the Department of Medicine, University of Montreal, and the Department of Biochemistry and Molecular Biology, Merck Sharp and Dohme Research Laboratories, Rahway, New Jersey.
    Search for more papers by this author
  • Marika Sarfati MD, PhD,

    Assistant Professor of Medicine
    1. Rheumatic Disease Unit Research Laboratory, and the Allergy Research Laboratory, Notre-Dame Hospital Research Center, Montreal, Quebec, Canada, affiliated with the Department of Medicine, University of Montreal, and the Department of Biochemistry and Molecular Biology, Merck Sharp and Dohme Research Laboratories, Rahway, New Jersey.
    Search for more papers by this author
  • Jean-Pierre Pelletier MD, FRCP(C)

    Associate Professor of Medicine, Corresponding author
    1. Rheumatic Disease Unit Research Laboratory, and the Allergy Research Laboratory, Notre-Dame Hospital Research Center, Montreal, Quebec, Canada, affiliated with the Department of Medicine, University of Montreal, and the Department of Biochemistry and Molecular Biology, Merck Sharp and Dohme Research Laboratories, Rahway, New Jersey.
    • Unité Rhumatismale, Hǒpital Notre-Dame, 1560 est, rue Sherbrooke, Montréal, Québec, Canada H2L 4K8
    Search for more papers by this author

Abstract

Objective. To identify and investigate the kinetic binding properties of interleukin-1 receptors (IL-1R), and examine the abilities of the 2 IL-1 isoforms to stimulate metalloprotease synthesis, in normal and osteoarthritic (OA) chondrocytes.

Methods. Receptor affinity and density were determined using radioligand binding experiments and flow cytometry. Immunocytochemical analysis and affinity cross-linking studies were performed for characterization of IL-1R.

Results. While no difference in receptor affinity between normal and OA chondrocytes was noted in binding studies (kd ˜30 pM), a 2-fold increase in receptor density was found in OA chondrocytes as compared with normal chondrocytes (mean 4,069 sites/cell versus 2,315 sites/cell). Flow cytometry experiments also showed a significant increase in receptor density in OA cells, as well as an enhancement in the percentage of positive cells in diseased cartilage compared with normal. Binding data for both IL-1 isoforms revealed a single class of binding sites and receptor specificity. Factors such as IL-2, interferon-sγ, tumor necrosis factor α, and bovine insulin did not compete with IL-1β. By covalent ligand cross-linking and electrophoretic analysis, only type I IL-1R, a protein of 80 kd, was detected on chondrocytes. By immunocytochemical analysis, IL-1R was identified at the cell membrane level, in both normal and OA chondrocytes. The presence of nuclear staining was also observed, but only in OA chondrocytes. Recombinant human IL-1 (α and β) induced the secretion of stromelysin and collagenase in a dose-dependent manner. The IL-1 concentration required for half-maximal metalloprotease stimulation was 3–4 times lower in OA chondrocytes than in normal cells.

Conclusion. These results indicate that OA chondrocytes have a higher sensitivity to the stimulation of metalloprotease synthesis by IL-1 than do normal cells. This could be related to the increased levels of IL-1R expressed in the OA cells. The implications of these findings with regard to the possible roles of IL-1 and IL-1R in the pathogenesis of OA are discussed.

Ancillary