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Invasive properties of fibroblast-like synoviocytes: correlation with growth characteristics and expression of MMP-1,
T C A Tolboom1, E Pieterman, W H van der Laan
1Department of Rheumatology, Leiden University Medical Centre, The Netherlands.
Background:
Matrix metalloproteinases (MMPs) have a pivotal role in the destruction of cartilage in rheumatoid arthritis (RA), which is mediated by the fibroblast-like synoviocytes (FLS).
Objective:
To examine the in vitro invasiveness of synoviocytes obtained from inflamed joints of patients with arthritis in relation to the expression of MMP 1-14, 17, 19, cathepsin-K, the tissue inhibitors of matrix metalloproteinases TIMP-1 and TIMP-2 by FLS.
Methods:
FLS were derived from 56 patients (30 with RA, 17 with osteoarthritis (OA), and nine with avascular necrosis (AVN)). Invasive growth of FLS through an artificial matrix (Matrigel) was measured in a transwell system. The number of cells that migrated through the matrix were counted. Proliferation rate was determined by counting the FLS after seven days of culturing. Expression of MMPs, cathepsin-K and TIMPs was investigated with reverse transcriptase-polymerase chain reaction and related to the expression of a household gene, beta-actin.
Results:
FLS from RA showed greater invasive growth than FLS from OA and AVN. The median number of cells that grew through the matrix membrane was 4788 for RA, significantly higher than the number for OA, 1875 (p<0.001) and for AVN, 1530 (p=0.014). The median rate of proliferation of RA FLS was 0.27 per day compared with OA 0.22 per day (p= 0.012) and AVN 0.25 per day, but there was no correlation between the rate of proliferation and invasive growth in vitro. FLS from RA and OA that expressed MMP-1, MMP-3, or MMP-10 were significantly more invasive (median number of invasive cells: 3835, 4248, 4990, respectively) than cells that did not express these MMPs (1605, p=0.03; 1970, p=0.004; 2360, p=0.012, respectively). There was also a significant relationship between the expression of MMP-1 and MMP-9 and the diagnosis RA (both p=0.013). The expression levels of mRNA for MMP-1 and MMP-2 correlated with the protein levels produced by the synoviocytes as measured by an enzyme linked immunosorbent assay (ELISA).
Conclusion:
FLS of RA invade more aggressively in a Matrigel matrix than OA and AVN FLS; this is not because of a higher rate of proliferation of RA FLS. The significant correlation between the expression of MMP-1, MMP-3, and MMP-10 and invasive growth in a Matrigel transwell system suggests that these MMPs play a part in the invasive growth of FLS obtained from patients with RA.
Insights
Fibroblast-like synoviocytes (FLS) from rheumatoid arthritis (RA) patients show more aggressive invasion than those from osteoarthritis (OA) and avascular necrosis (AVN) patients. Matrix metalloproteinases (MMPs) like MMP-1, MMP-3, and MMP-10 are linked to this increased invasiveness in RA.
Area of Science:
- Rheumatology
- Cell Biology
- Biochemistry
Background:
- Fibroblast-like synoviocytes (FLS) mediate cartilage destruction in rheumatoid arthritis (RA).
- Matrix metalloproteinases (MMPs) are implicated in the pathogenesis of RA.
Purpose of the Study:
- To investigate the in vitro invasiveness of FLS from arthritis patients.
- To correlate FLS invasiveness with the expression of MMPs, cathepsin-K, and tissue inhibitors of metalloproteinases (TIMPs).
Main Methods:
- FLS were isolated from 56 patients with RA, osteoarthritis (OA), or avascular necrosis (AVN).
- In vitro invasiveness was assessed using a Matrigel transwell system.
- Gene expression of MMPs, cathepsin-K, and TIMPs was analyzed via reverse transcriptase-polymerase chain reaction (RT-PCR).
Main Results:
- FLS from RA patients exhibited significantly greater invasive growth compared to OA and AVN FLS.
- A positive correlation was found between the expression of MMP-1, MMP-3, and MMP-10 and FLS invasiveness.
- FLS invasiveness was not correlated with proliferation rate, and MMP-1 and MMP-9 expression was significantly associated with RA diagnosis.
Conclusions:
- FLS from RA patients demonstrate enhanced invasive capabilities in vitro.
- Specific MMPs, including MMP-1, MMP-3, and MMP-10, are likely involved in the invasive behavior of RA FLS.
- These findings highlight the role of MMPs in the destructive processes of rheumatoid arthritis.