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J Rheumatol. 2000 Apr;27(4):859-65.

Cathepsin B and its endogenous inhibitor cystatin C in rheumatoid arthritis synovium.

Author information

1
Institute of Pathology and the Clinic of Orthopedics, University of Mainz, Germany.

Abstract

OBJECTIVE:

To compare the expression of cathepsin B and its endogenous inhibitor cystatin C in synovial tissue of patients with rheumatoid arthritis (RA) and to determine the cell type expressing cystatin C.

METHODS:

The expression of cathepsin B and cystatin C was studied by immunohistochemistry in synovial tissue of 10 patients with RA and compared to healthy controls. Applying double labeling methods, the expression of cathepsin B was compared to that of cystatin C. To determine the cell type expressing cystatin C, double labeling with anti-CD68 (PG-M1) was performed.

RESULTS:

Both cystatin C and cathepsin B were strongly expressed in synoviocytes of patients with RA. Furthermore, fibroproliferative tissue at the site of cartilage and bone destruction contained fibroblast-like and macrophage-like cells positive for cystatin C and cathepsin B, whereas normal synovial tissue exhibited only limited expression of these molecules. Osteoclasts revealed positive staining for CD68 and cystatin C, but not for cathepsin B.

CONCLUSION:

Cystatin C is a product of both macrophage-like and fibroblast-like synoviocytes. The strong expression of both the matrix degrading cysteine proteinase cathepsin B and the cysteine proteinase inhibitor cystatin C in rheumatoid synovium, particularly at the sites of bone and cartilage erosion, suggests that cystatin C--although increased--is not sufficient to prevent matrix degradation by cathepsin B.

PMID:
10782807
[Indexed for MEDLINE]

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