Expression of cysteine proteinases cathepsins B and K and of cysteine proteinase inhibitor cystatin C in giant cell tumor of tendon sheath.

The expression of cysteine proteinases cathepsins B and K and of the endogenous inhibitor of cysteine proteinases, cystatin C, was investigated in tissue specimens of patients with giant cell tumor of tendon sheath (GCTTS). Expression of both enzymes was examined by immunohistochemistry in tissue specimens of 14 patients with GCTTS. Applying double-labeling techniques, the coexpression of cathepsin B and its major endogenous inhibitor cystatin C was additionally studied. Cells expressing the respective proteins were further characterized with the macrophage markers HAM56 and anti-CD68 (clone PG-M1). Cathepsin B could be detected in numerous HAM56-positive mononuclear cells (MC), but only in very few giant cells (GC). In contrast, cathepsin K was predominantly identified in GC that were also strongly immunoreactive for cystatin C and CD68. Coexpression of cathepsin B and cystatin C occurred only in a few MC. The strong expression of both cathepsin B and K suggests that in GCTTS, bone erosion might be mediated not only by pressure of the proliferative tissue, but also by matrix-degrading cysteine proteinases. Because previous studies showed that osteoclasts express high levels of CD68, cathepsin K, and cystatin C but not of cathepsin B, our study contributes to the view that GC of GCTTS and osteoclasts are closely associated.

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

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.

Comparative analysis of cathepsin L, cathepsin D, and collagenase messenger RNA expression in synovial tissues of patients with rheumatoid arthritis and osteoarthritis, by in situ hybridization.

OBJECTIVE: To compare the expression of cathepsin L, cathepsin D, and collagenase messenger RNA (mRNA) in synovial specimens from patients with rheumatoid arthritis (RA) and osteoarthritis (OA). METHODS: The expression of cathepsins L and D as well as collagenase mRNA in synovial tissues from 8 patients with RA, 6 patients with OA, and 2 patients with noninflamed joints was evaluated using in situ hybridization with digoxigenin-labeled RNA probes. RESULTS: Both RA and OA synovial tissue expressed cathepsins L and D as well as collagenase mRNA. The expression of the cathepsins was markedly higher in interstitial regions and, to some extent, in perivascular infiltrates of RA synovial tissue compared with OA specimens. CONCLUSION: Cathepsins L and D mRNA are expressed differently in RA and OA synovial tissues, supporting the concept that these enzymes may contribute to the influx of mononuclear cells into RA synovium. Moreover, the data reveal that the expression of collagenase and cathepsins in RA and OA synovial lining is otherwise largely similar, and suggest that the adhesion of synovial cells to cartilage mediates the invasive destructive process in RA.

Expression of E-selectin messenger RNA and protein in rheumatoid arthritis.

OBJECTIVE: To examine the de novo synthesis and cellular distribution of the E-selectin adhesion molecule in synovial tissues obtained from patients with rheumatoid arthritis (RA). METHODS: Immunohistochemistry techniques combined with in situ hybridization were used to examine RA synovium. RESULTS: There were numerous endothelial cells positive for E-selectin and E-selectin messenger RNA in the RA synovial membranes. Moreover, E-selectin expression appeared to correlate with inflammatory activity. CONCLUSION: The strong vascular expression of E-selectin indicates an activation of endothelial cells in the recruitment of cells associated with the chronic inflammation of RA.

Expression of vascular cell adhesion molecule-1 mRNA and protein in rheumatoid synovium demonstrated by in situ hybridization and immunohistochemistry.

BACKGROUND: Vascular cell adhesion molecule-1 (VCAM-1) is expressed in synovial tissue of patients with rheumatoid arthritis. VCAM-1-protein has been demonstrated in nonvascular cells beside a vascular expression of this molecule. There are conflicting results about the nonvascular cell types expressing VCAM-1. EXPERIMENTAL DESIGN: For the evaluation of VCAM-1 expression in rheumatoid synovium, this molecule has been demonstrated by alkaline phosphatase anti-alkaline phosphatase (APAAP) technique. Furthermore, VCAM-1 mRNA has been demonstrated by in situ hybridization to evaluate de novo synthesis of this molecule in vivo. To elucidate the nature of the cell types expressing VCAM-1 mRNA, this molecule has been shown by combined in situ hybridization for VCAM-1 and immunohistochemistry in the same tissue section. Double labeling has been performed with anti-collagen type IV monoclonal antibodies to delineate endothelial cells and pericytes and with anti-CD68 antibodies to elucidate the expression of VCAM-1 mRNA in fibroblast-like (type B) or macrophage-like (type A) synoviocytes. RESULTS: Although it has been reported that VCAM-1 occurs on endothelial cells after cytokine stimulation, we show that vascular expression of VCAM-1 mRNA and protein was minimal and restricted to small vessels beneath the lining cell layer. Further expression of VCAM-1 mRNA could be demonstrated in pericytes outside the collagen type IV containing vascular basement membrane. With respect to the expression of VCAM-1 in the synovial lining layer, we could clearly demonstrate by combined in situ hybridization and immunohistochemistry that CD68 positive cells of the monocyte/macrophage lineage in the lining layer (type A cells) do not express VCAM-1 mRNA and that the expression of VCAM-1 mRNA in the lining layer was restricted to fibroblast-like synoviocytes (type B cells). Scattered stromal cells revealing VCAM-1 mRNA were also CD68 negative. CONCLUSIONS: The strong expression of VCAM-1 in the fibroblast-like cells of RA synovium and the lack of expression in the vascular endothelium suggest that the major role of VCAM-1 appears to be associated with the proliferating synovial cells prone to attach and subsequently invade articular cartilage.

Detection of insulin-like growth factor I and II in synovial tissue specimens of patients with rheumatoid arthritis and osteoarthritis by in situ hybridization.

OBJECTIVE: To study the expression of insulin-like growth factor I and II (IGF I and II) in synovial tissue specimen of patients with rheumatoid arthritis (RA) and osteoarthritis (OA). METHODS: Synovial tissue sections were examined for the expression of IGF I and II by in situ hybridization using digoxigenin labeled antisense and sense RNA probes. RESULTS: The antisense probe of IGF I reacted with all specimens. IGF II mRNA was expressed in 7/7 RA and 4/5 OA tissues. Cells of the synovial lining and subsynovial layer bound both antisense probes, whereas inflammatory infiltrates of RA tissues were labeled rarely. CONCLUSION: The significant number of cells in the synovium that express IGF I and II mRNA suggests a role of IGF in repair mechanisms of articular cartilage in response to injury and effects on fibroblast growth within the synovium.

A new model for rheumatoid arthritis generated by engraftment of rheumatoid synovial tissue and normal human cartilage into SCID mice.

OBJECTIVE: A new animal model was used to study the interaction between rheumatoid synovial cells and cartilage and to explore the cellular basis of rheumatoid joint destruction. METHODS: Fresh synovial tissue derived from patients with rheumatoid arthritis was implanted with normal human cartilage into SCID mice, either subcutaneously or under the renal capsule, for up to 304 days. The implants were analyzed by light and electron microscopy, as well as by immunohistochemistry and in situ hybridization. RESULTS: Human synovial tissue and cartilage implanted in SCID mice are maintained by the animals for up to 304 days. After 35 days, focal erosions occur at the site of attachment of synovial lining cells to the cartilage. After 105 days, a pannus-like formation, consisting of proliferating synovial fibroblast-like cells invading the cartilage, is observed. The fibroblast nature of these cells was supported by observation of only focal expression of the macrophage markers CD14 and CD68. Cells at the immediate site of cartilage destruction express messenger RNA for cathepsin L, whereas cathepsin D messenger RNA was detected in subsynovial regions away from the site of destruction. The human origin of the tissue involved in cartilage destruction was demonstrated using monoclonal antibodies to HLA-ABC and human type IV collagen. CONCLUSION: The present approach introduces a novel in vivo model of rheumatoid arthritis for the study of the molecular and cellular mechanisms of rheumatoid joint destruction at sites of synovial attachment to cartilage. In this model, the SCID mouse acts as a useful host for studying the properties of rheumatoid synovium in the absence of circulating human blood components.

Cytokines and oncogenes in cellular interactions of rheumatoid arthritis.

Rheumatoid arthritis (RA) is a chronic systemic disorder of unknown etiology. Most of its debilitation sequelae are derived from progressive destruction of joints. The affected joints exhibit inflammation, abnormal immune responses and synovial hyperplasia. Although growth factors and cytokines derived from macrophages and endothelial cells contribute to the perpetuation of the inflammatory process, activated transformed-appearing synovial fibroblasts mediate cartilage and bone destruction. Based on the observation that synovial hyperplasia is associated with a transformed-appearing phenotype and an upregulated expression of protooncogenes and matrix degrading enzymes, the present studies are designed to explore the role of a heretofore unknown (retro) virus-like particle in the pathogenesis of RA.