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-1␤ (IL-1␤)-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-1␤.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-1␤. Among all proteases, MMP-3 was by far the most strongly expressed, although it was strongly downregulated in late-stage OA specimens. Expression of MMP-3 was higher in vitro than in vivo and was up-regulated by IL-1␤. 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-1␤.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-1␤ stimulation of articular chondrocytes might not be a good model for the matrix catabolism in OA cartilage.Osteoarthritic (OA) cartilage degeneration as well as cartilage destruction in rheumatoid arthritis depend, at least to a significant degree, on enzymatic degradation of matrix components. Two types of molecules, collagen fibrils and the proteoglycan aggrecan, represent the major targets in terms of enzymatic activity and functional loss of the cartilage matrix as a result of damage to these molecules. Whereas degradation of collagen fibrils leads to matrix instability with tissue swelling, degradation of proteoglycans leads to cartilage softening and loss of fixed charges (1), both of which are classic features of cartilage destruction.Catabolism of both types of molecules is supposed to involve different types of enzymes, largely from 2 protease families: matrix metalloproteinases (MMPs) and the "A disintegrin and metalloproteinases with thrombospondin type 1 motif" (ADAM-TS). The initial degradation of collagen fibrils (within the triple-helical region) depends on cleavage at the collagenase site, for which there exist 2 major candidate enzymes...

Hsp90 mediates insulin‐like growth factor 1 and interleukin‐1β signaling in an age‐dependent manner in equine articular chondrocytes

“…Studies of human articular chondrocytes have shown that in vivo levels of MMP13 are significantly lower than in cells cultured in vitro, but the responses to IL-1␤ are similar (49). Our analysis of MMP13 mRNA expression levels in articular chondrocytes showed that basal levels were lowest in the youngest animals and increased ϳ3-fold in adult and mature animals.…”

Matrix‐degrading proteases ADAMTS4 and ADAMTS5 (disintegrins and metalloproteinases with thrombospondin motifs 4 and 5) are expressed in human glioblastomas

“…35 In chondrocytes, ADAMTS4 was induced by Il-1b. 36 ADAMTS4 and 5 inductions in glioblastoma cells is partly similar, but not completely identical as in mesenchymal cells. It is well known that TGF-b is a major cytokine produced by high grade gliomas and is, therefore, an example for the regulation of these proteases in the tumor microenvironment.…”

Selective and non-selective metalloproteinase inhibitors reduce IL-1-induced cartilage degradation and loss of mechanical properties

“…Proinflammatory stimuli may upregulate transcription of aggrecanase genes (Bau, et al, 2002;Koshy, et al, 2002), and there is mounting evidence for substantial post-translational processing of the enzymes that alter aggrecanase activity and specificity (Pratta, et al, 2003a). In human chondrosarcoma cells and bovine cartilage explants, MMP-17 (MT4-MMP) appears to be responsible for C-terminal truncation of ADAMTS-4, a process which converts the enzyme from one which can cleave only the sGAG-rich region to one which can also cleave the interglobular domain (IGD) (Gao, et al, 2004;Patwari, et al, 2005).…”