Collagenase at Sites of Cartilage Erosion in the Rheumatoid Joint

Abstract

Immunolocalization studies of rheumatoid tissues employing specific synovial collagenase antibody have demonstrated immunoreactive enzyme at the cartilage/pannus junction. Collagenase was not detected in chondrocytes or the cartilage matrix remote from the resorbing front, and relatively little enzyme was observed in the hypertrophied synovial membrane itself. These observations directly support the idea that synovial collagenase participates in cartilage erosion in rheumatoid arthritis.A fundamental feature of the joint damage that occurs in rheumatoid arthritis is progressive erosion of the articular cartilage by the hypertrophic synovium or pannus (1,2). This process involves both proteoglycan and collagen removal, but because the turnover of cartilage proteoglycan is significantly greater than the turnover of collagen, it is likely that irreversible cartilage damage is attributable to collagen breakdown. The observation that rheumatoid synovial tissue in culture produces large quantities of neutral collagenase (3) has led to speculation on the role of this enzyme in the joint erosion of rheumatoid arthritis (43). Highly purified synovial collagenase has been shown to degrade cartilage collagen (6,7), insoluble collagen fibers (8), and slices of human articular cartilage (9), and it is relatively unaffected by cartilage proteoglycans (10). However more definitive evidence of collagenase involvement has awaited the demonstration and localization of the enzyme directly in rheumatoid tissues. This report presents our findings with a specific anticollagenase antibody for immunolocalization studies of joint tissues in rheumatoid arthritis. MATERIALS AND METHODS MaterialsDulbecco's modified Eagle's medium containing HEPES buffer and 0.85 g/L sodium bicarbonate was supplied by Flow Laboratories, Irvine, Scotland. Rabbit anti-(sheep serum proteins) serum was purchased from Dakopatts, A/S, Denmark. FITC-labeled rabbit antibodies to sheep IgG were acquired from Wellcome Reagents Ltd, Beckenham, England, and unlabeled rabbit antibodies to sheep IgG were purchased from Miles-Yeda Ltd, Rehovot, Israel. Rheumatoid Synovial CollagenaseRheumatoid synovial tissue removed by synovectomy was cut into fragments and explanted into culture flasks containing Dulbecco's modified Eagle's medium with HEPES buf-

Histopathology of the rheumatoid lesion

“…Fassbender (4,18) has recently described immature mesenchymal cells as being responsible for cartilage erosion in very early rheumatoid disease, and mast cells and PMNs were the first to appear in very early stages of rat adjuvant arthritis (29). However, our observations of collagenase at thc cartilage-pannus interface in joints from patients with advanced rheumatoid disease suggest that cartilage erosion is not limited to the early stages of disease activity (8,9).…”

“…This is particularly well-demonstrated in Figure 4, where PMNs and macrophages are each shown to be locally concentrated at different micro-foci of the same junction. Moreover, we believe that cartilage erosion may represent a transient, discontinuous process occurring in local regions along the cartilage-pannus junction (8,9), and it is probably determined at any one time by specific cell types and their reaction to microenvironmental conditions. Although our studies suggest that the cellular composition of the rheumatoid lesion is subject to change, we do not know the sequence of cellular events, or the relative time that each cell type occupies the junctional region.…”

Immunohistochemical detection and immunochemical analysis of type II collagen degradation in human normal, rheumatoid, and osteoarthritic articular cartilages and in explants of bovine articular cartilage cultured with interleukin 1.

“…Most rheumatoid cartilage was examined from sites at or close to the cartilage-synovial junction. The data indicate that not only may type II collagen degradation occur at the cartilage-synovial junction, associated with mononuclear cell infiltration and pannus formation (3,(45)(46)(47), but that it also occurs around the chondrocytes more remote from the articular surface and remote from the synovium and synovial fluid. Earlier, ultramorphological studies of rheumatoid articular cartilage, using cationic dyes, also showed that proteoglycans were lost and collagen was damaged in the deep zone cartilage (4).…”

Matrix Metalloproteinase Production by COOH-Terminal Heparin-Binding Fibronectin Fragment in Rheumatoid Synovial Cells

“…IL-1, found in the elevated levels in RA synovium (Wang et al, 1997) and synovial fluid (Kahle et al, 1992), is considered to be one of those factors. Up-regulation and overexpression of MMPs are commonly found in rheumatoid joint destruction (Firestein et al, 1991), and increased levels of collagenase are found in RSF at the cartilage-pannus junction (Wooley et al, 1977). Of these enzymes, particular attention has focused on MMP-1 (collagenase 1) and MMP-13 (collagenase 3) because they are induced in response to IL-1 and tumor necrosis factor (Vincenti, 2001).…”

“…RSF extend out over the articular surface of cartilage, including the point of cartilage-pannus junction, where they express elevated collagenase levels (Wooley et al, 1977). Matrix metalloproteinases (MMPs) are thought to be critical players in rheumatoid joint destruction (Firestein et al, 1991).…”