title: Relative messenger RNA expression profiling of collagenases and aggrecanases in human articular chondrocytes in vivo and in vitro.
abstract: 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-1beta (IL-1beta)-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-1beta.
  
  
  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-1beta. 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-1beta. 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-1beta.
  
  
  CONCLUSIONS
  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-1beta stimulation of articular chondrocytes might not be a good model for the matrix catabolism in OA cartilage.
authors.affiliation: Cartilage Research, Department of Pathology, University of Erlangen-Nuremberg, Krankenhausstrasse 8-10, D-91054 Erlangen, Germany.
authors.forename: Brigitte
authors.initials: B
authors.lastname: Bau
authors.forename: Pia M
authors.initials: PM
authors.lastname: Gebhard
authors.forename: Jochen
authors.initials: J
authors.lastname: Haag
authors.forename: Thomas
authors.initials: T
authors.lastname: Knorr
authors.forename: Eckart
authors.initials: E
authors.lastname: Bartnik
authors.forename: Thomas
authors.initials: T
authors.lastname: Aigner
mesh_terms: D051722:ADAM Proteins; D000071121:ADAMTS4 Protein; D000071116:ADAMTS5 Protein; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000464:Alginates; D002358:Cartilage, Articular / Q000166:cytology / Q000201:enzymology; D002478:Cells, Cultured; D019902:Chondrocytes / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D017364:Collagenases / Q000235:genetics*; D020869:Gene Expression Profiling; D015971:Gene Expression Regulation, Enzymologic; D020723:Glucuronic Acid; D006603:Hexuronic Acids; D006801:Humans; D066298:In Vitro Techniques; D007375:Interleukin-1 / Q000494:pharmacology; D020781:Matrix Metalloproteinase 1 / Q000235:genetics; D053509:Matrix Metalloproteinase 13; D019278:Matrix Metalloproteinase 3 / Q000235:genetics; D053504:Matrix Metalloproteinases, Membrane-Associated; D008666:Metalloendopeptidases / Q000235:genetics*; D008863:Microspheres; D008875:Middle Aged; D011348:Procollagen N-Endopeptidase; D012333:RNA, Messenger / Q000032:analysis; D019914:Taq Polymerase
chemical_list: D000464:Alginates; D006603:Hexuronic Acids; D007375:Interleukin-1; D012333:RNA, Messenger; D020723:Glucuronic Acid; D019914:Taq Polymerase; D051722:ADAM Proteins; D000071116:ADAMTS5 Protein; C121532:ADAMTS5 protein, human; D017364:Collagenases; C507079:MMP13 protein, human; D053509:Matrix Metalloproteinase 13; D053504:Matrix Metalloproteinases, Membrane-Associated; D008666:Metalloendopeptidases; D011348:Procollagen N-Endopeptidase; D019278:Matrix Metalloproteinase 3; D020781:Matrix Metalloproteinase 1; D000071121:ADAMTS4 Protein