Relative messenger RNA expression profiling of collagenases and aggrecanases in human articular chondrocytes in vivo and in vitro

• Published in: Arthritis and rheumatism Vol. 46; no. 10; pp. 2648 - 2657
• Main Authors: Bau, Brigitte, Gebhard, Pia M., Haag, Jochen, Knorr, Thomas, Bartnik, Eckart, Aigner, Thomas
• Format: Journal Article
• Language: English
• Published: New York Wiley Subscription Services, Inc., A Wiley Company 01-10-2002; Wiley
• Subjects: ADAM Proteins; ADAMTS4 Protein; ADAMTS5 Protein; Adult; Aged; Aged, 80 and over; Alginates; Biological and medical sciences; Cartilage, Articular - cytology; Cartilage, Articular - enzymology; Cells, Cultured; Chondrocytes - cytology; Chondrocytes - drug effects; Chondrocytes - enzymology; Collagenases - genetics; Diseases of the osteoarticular system; Gene Expression Profiling; Gene Expression Regulation, Enzymologic; Glucuronic Acid; Hexuronic Acids; Humans; In Vitro Techniques; Interleukin-1 - pharmacology; Matrix Metalloproteinase 1 - genetics; Matrix Metalloproteinase 13; Matrix Metalloproteinase 3 - genetics; Matrix Metalloproteinases, Membrane-Associated; Medical sciences; Metalloendopeptidases - genetics; Microspheres; Middle Aged; Osteoarthritis; Procollagen N-Endopeptidase; RNA, Messenger - analysis; Taq Polymerase; Human; Stromelysin 1; Chondrocyte; Enzyme; Pathogenesis; Cytokine; Diseases of the osteoarticular system; Metalloendopeptidases; Interleukin 1β; Gene expression; In vitro; Peptidases; In vivo; Regulation(control); Messenger RNA; Articular cartilage; Arthropathy; Hydrolases; Degenerative disease; Molecular biology; Osteoarthritis; Interstitial collagenase; Quantitative analysis
• ISSN: 0004-3591; 1529-0131
• DOI: 10.1002/art.10531

Objective
Osteoarthritic (OA) cartilage destruction depends on collagen‐ and aggrecan‐degrading proteases such as collagenases (MMP‐1 and MMP‐13), stromelysin (MMP‐3), MMP‐14, as well as the so‐called aggrecanases (ADAM‐TS4 and ADAM‐TS5). In this study, we tried to clarify whether these proteases are expressed in vivo in human normal and OA cartilage (and whether they are up‐regulated or down‐regulated during the disease process) and in interleukin‐1β (IL‐1β)–stimulated chondrocytes in vitro.
Methods
Quantitative polymerase chain reaction assays were developed and performed on RNA isolated directly from normal and degenerative cartilage tissue as well as from primary human articular chondrocytes cultured with and without IL‐1β.
Results
In vivo, MMP‐1 was detectable only at very low levels in any condition. MMP‐13 expression was low in normal and early degenerative cartilage but was strongly up‐regulated in late‐stage OA specimens. MMP‐1 and MMP‐13 were expressed much higher in vitro than in vivo and were up‐regulated by IL‐1β. Among all proteases, MMP‐3 was by far the most strongly expressed, although it was strongly down‐regulated in late‐stage OA specimens. Expression of MMP‐3 was higher in vitro than in vivo and was up‐regulated by IL‐1β. ADAM‐TS5 and MMP‐14 were expressed in all sample groups. Expression of ADAM‐TS4 was very low in vivo and was induced in vitro after stimulation by IL‐1β.
Conclusion
Our expression data clearly support MMP‐13 as the major collagenase in OA cartilage. The most strongly expressed aggrecanase was ADAM‐TS5. ADAM‐TS4 was expressed only at a very low level in normal cartilage and was only slightly up‐regulated in OA cartilage, casting doubt on this enzyme being the relevant aggrecanase of articular cartilage. Results of our study show that expression of many enzymes is significantly different in vitro and in vivo and suggest that IL‐1β stimulation of articular chondrocytes might not be a good model for the matrix catabolism in OA cartilage.