Regional assessment of articular cartilage gene expression and small proteoglycan metabolism in an animal model of osteoarthritis

Abstract

Osteoarthritis (OA), the commonest form of arthritis and a major cause of morbidity, is characterized by progressive degeneration of the articular cartilage. Along with increased production and activation of degradative enzymes, altered synthesis of cartilage matrix molecules and growth factors by resident chondrocytes is believed to play a central role in this pathological process. We used an ovine meniscectomy model of OA to evaluate changes in chondrocyte expression of types I, II and III collagen; aggrecan; the small leucine-rich proteoglycans (SLRPs) biglycan, decorin, lumican and fibromodulin; transforming growth factor-β; and connective tissue growth factor. Changes were evaluated separately in the medial and lateral tibial plateaux, and were confirmed for selected molecules using immunohistochemistry and Western blotting. Significant changes in mRNA levels were confined to the lateral compartment, where active cartilage degeneration was observed. In this region there was significant upregulation in expession of types I, II and III collagen, aggrecan, biglycan and lumican, concomitant with downregulation of decorin and connective tissue growth factor. The increases in type I and III collagen mRNA were accompanied by increased immunostaining for these proteins in cartilage. The upregulated lumican expression in degenerative cartilage was associated with increased lumican core protein deficient in keratan sulphate side-chains. Furthermore, there was evidence of significant fragmentation of SLRPs in both normal and arthritic tissue, with specific catabolites of biglycan and fibromodulin identified only in the cartilage from meniscectomized joints. This study highlights the focal nature of the degenerative changes that occur in OA cartilage and suggests that altered synthesis and proteolysis of SLRPs may play an important role in cartilage destruction in arthritis.

Roles of inflammatory and anabolic cytokines in cartilage metabolism: signals and multiple effectors converge upon MMP-13 regulation in osteoarthritis

“…However, studies in animal models (Chambers et al , 2002; Matyas et al , 2002; Young et al , 2005) and analyses of cartilage samples or body fluids from OA patients (Aigner et al , 1999; Nelson et al , 1998; Rousseau et al , 2004) indicate that differential COL2A1 expression may depend upon the zone of cartilage analyzed in conjunction with the stage of OA progression (Aigner et al , 1997; Aigner et al , 2001). These observations are supported by recent large-scale expression profiling studies, including our own, using full-thickness cartilage, demonstrating that many collagen genes, including COL2A1 , are upregulated in late-stage OA (Aigner et al ., 2006; Ijiri et al ., 2008).…”

Histological and molecular characterisation of feline humeral condylar osteoarthritis

“…The patterns of identified molecular changes are dependent on the species [14], joint [15], location within the joint [16] and stage of the disease process [17,18] although broad similarities in patterns of differential gene expression in end-stage OA are observed between species [14]. …”

A hexadecylamide derivative of hyaluronan (HYMOVIS®) has superior beneficial effects on human osteoarthritic chondrocytes and synoviocytes than unmodified hyaluronan

“…Proteins were then precipitated with 5 volumes of ethanol at 4°C for 16 hours, redissolved in reducing SDS-PAGE buffer, boiled for 5 minutes and separated on 10% SDS-PAGE gels (Invitrogen). Separated proteins were transferred to nitrocellulose membranes and MMP-13 protein detected using a monoclonal antibody (Abcam 39012) [28,29]. …”