Differential induction and regulation of matrix metalloproteinases in osteoarthritic tissue and fluid synovial fibroblasts.
OBJECTIVE
To investigate the secretion profiles of matrix metalloproteinases (MMP) and their inhibitors (TIMP) in synovial fluid-derived fibroblasts and to compare them with those of tissue-derived fibroblasts.


METHODS
Fibroblast cultures established from synovial tissues (TSC) and fluids (FSC) of the same OA patients were stimulated with tumor necrosis factor(TNF)-alpha, interleukin(IL)-1alpha, IL-1beta, IL-6 and a combination of TNFalpha and IL-1beta. Cocultures of fibroblasts and cartilage were stimulated either with the cytokine combination or with osteoarthritic synovial fluid. Secretion of MMP-1, MMP-3, MMP-8, MMP-13, TIMP-1, and TIMP-2 was measured by enzyme-linked immunosorbent assay. Gelatin zymography and immunoblotting were performed to demonstrate enzyme activity.


RESULTS
TNFalpha, IL-1alpha, and IL-1beta led to marked increases in MMP-1 and MMP-3 release (up to 4.2-fold and 547-fold, respectively) by synovial fibroblasts, whereas secretion of MMP-13 was induced by concomitant administration of TNFalpha and IL-1beta. Expression of intracellular MMP-8 was stimulated by cytokines, but adhesion of synovial fibroblasts to cartilage was required for the release. Throughout the study, significantly higher levels of secreted MMPs were observed in stimulated FSC compared to TSC cultures. Furthermore, increases in MMP secretion were not accompanied by increases in secreted TIMP-1 and TIMP-2, resulting in marked imbalances between enzyme and inhibitor levels.


CONCLUSIONS
The results provide strong evidence for a significant impact of synovial-derived MMPs on cartilage destruction in OA. In this context, fibroblasts present in the synovial fluid appeared to play an outstanding role.
Fuchs
S
S
Department of Orthopaedics, University Hospital of Muenster, Albert-Schweitzer-Strasse 33, D-48129 Muenster, Germany. fuchssu@uni-muenster.de
Skwara
A
A
Bloch
M
M
Dankbar
B
B
D000368:Aged; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D006801:Humans; D007378:Interleukins / Q000378:metabolism; D020782:Matrix Metalloproteinases / Q000378:metabolism*; D008875:Middle Aged; D013582:Synovial Fluid / Q000166:cytology* / Q000187:drug effects* / Q000502:physiology; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000378:metabolism; D019716:Tissue Inhibitor of Metalloproteinase-2 / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
D007378:Interleukins; D019715:Tissue Inhibitor of Metalloproteinase-1; D014409:Tumor Necrosis Factor-alpha; D019716:Tissue Inhibitor of Metalloproteinase-2; D020782:Matrix Metalloproteinases