Rheumatoid arthritis.
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Antirheumatic Agents↗
Biomedical subjects
S Gay
Publications and source records attributed to S Gay.
Prevalence of TTV DNA and GBV-C RNA in patients with systemic sclerosis, rheumatoid arthritis, and osteoarthritis does not differ from that in healthy blood donors.
OBJECTIVE: To determine the prevalence of GB virus-C (GBV-C) RNA and TT virus (TTV) DNA in patients with systemic sclerosis (SSc), rheumatoid arthritis (RA), and osteoarthritis (OA) as well as to compare the autoantibody pattern in patients with SSc with and without evidence of viral infection. PATIENTS AND METHODS: The study included 168 patients (84 SSc, 41 RA, and 43 OA) diagnosed according to the American College of Rheumatology criteria and 122 volunteer blood donors. The presence of GBV-C RNA and TTV DNA in serum was assessed by nested reverse transcriptase-polymerase chain reaction (RT-PCR) and semi-nested PCR, respectively. Autoantibodies in patients with SSc were determined by enzyme linked immunosorbent assay (ELISA) and Hep-2 immunofluorescence. RESULTS: TTV-DNA was detected in 10/84 (12%) patients with SSc, 9/41 (22%) patients with RA, 3/43 (7%) patients with OA, and 16/122 (13%) blood donors. GBV-C RNA was present in 4/84 (5%) patients with SSc, 2/43 (5%) patients with OA, and 5/122 (4%) blood donors. No patient with RA was positive for GBV-C RNA. One patient with SSc and one patient with OA showed a double infection with GBV-C and TTV. 74/84 (88%) patients with SSc were positive for at least one autoantibody species tested: 18/84 (21%) showed anticentromeric autoantibodies, 55/84 (66%) a speckled (36/84 (43%) fine, 19/84 (23%) coarse), and 20/84 (24%) a homogeneous nuclear Hep-2 pattern, and 21/84 (25%) had antinucleolar autoantibodies. Anti-Scl-70 antibodies were found in 31/84 (37%) and anti-RNP antibodies in 5/84 (6%) patients with SSc. No differences in the autoantibody pattern in patients with SSc with or without viral infection could be detected. CONCLUSION: The prevalence of GBV-C RNA and TTV DNA in serum samples from patients with SSc, RA, and OA was low and comparable with that in blood donors. A continuing infection with TTV and or GBV-C was not associated with a significant change in the autoantibody pattern in patients with SSc. These data provide no evidence for an association between GBV-C and/or TTV infections and SSc and/or arthritis (RA and OA).
Adult↗
Dual inhibition of 5-lipoxygenase and cyclooxygenases 1 and 2 by ML3000 reduces joint destruction in adjuvant arthritis.
OBJECTIVE: To search for potential new therapies to inhibit the progression of joint destruction in patients with rheumatoid arthritis. METHODS: We evaluated the dual acting antiinflammatory drug ML3000 (2,2-dimethyl-6-(4-chlorophenyl)-7-phenyl-2,3-dihydro- H-pyrrolizine-5-yl) acetic acid, a dual inhibitor of 5-lipoxygenase (5-LOX) as well as both cyclooxygenases (COX-1 and COX-2) in the rat model of adjuvant arthritis. On Day 0, female Lewis rats (5 per group) were injected intradermally with complete Freund's adjuvant at base of the tail. Treatment began on Day 2; the rats received ML3000 (20 or 80 mg/kg/day) twice daily 7 h apart for 28 days and were then sacrificed. To reduce pain, the positive control group and 2 treatment groups received paracetamol (3 mg/ml water). Joint histology was scored for synovial cell proliferation, fibroproliferative pannus, and cartilage and bone erosions, as well as diffuse leukocyte infiltrates. RESULTS: Daily doses of 20 or 80 mg/kg ML3000 significantly reduced the arthritis associated deficiency of body growth, the edema/erythema score, and splenomegaly. In the ankle joint, ML3000 significantly reduced the overall histological score, synovial cell proliferation, and bone/cartilage erosions, and inhibited the appearance of fibroproliferative pannus. The addition of paracetamol in the drinking water had no influence. No side effects were noted. CONCLUSION: ML3000 is an antiarthritic drug with a high gastrointestinal tolerability, which can reduce synovial cell proliferation and joint erosion and is capable of markedly suppressing prostaglandin synthesis.
Acetates↗
Fibroblast biology. Role of synovial fibroblasts in the pathogenesis of rheumatoid arthritis.
There is growing evidence that activated synovial fibroblasts, as part of a complex cellular network, play an important role in the pathogenesis of rheumatoid arthritis. In recent years, significant progress has been made in elucidating the specific features of these fibroblasts. It has been understood that although macrophage and lymphocyte secreted factors contribute to their activation, rheumatoid arthritis synovial fibroblasts (RA-SFs) do not merely respond to stimulation by pro-inflammatory cytokines, but show a complex pattern of molecular changes also maintained in the absence of external stimulation. This pattern of activation is characterized by alterations in the expression of regulatory genes and signaling cascades, as well as changes in pathways leading to apoptosis. These together result in the upregulation of adhesion molecules that mediate the attachment of RA-SFs to the extracellular matrix and in the overexpression of matrix degrading enzymes that mediate the progressive destruction of the joints. In addition, activated RA-SFs exert specific effects on other cell types such as macrophages and lymphocytes. While the initiating step in the activation of RA-SFs remains elusive, several key pathways of RA-SF activation have been identified. However, there is so far no single, specific marker for this phenotype of RA-SF. It appears that activated RA-SFs are characterized by a set of specific properties which together lead to their aggressive behavior.
Animals↗
Activation of the IL-4 STAT pathway in rheumatoid synovium.
STATs act as second messenger after binding of a signaling molecule to its receptor. IL-4 STAT is directly involved in the IL-4-dependent gene transcription in the nucleus. We examined the expression and activation of IL-4 STAT and its related kinase Jak-1 in rheumatoid synovium. Rheumatoid arthritis (RA) synovial frozen sections of patients with short-term (<1 year) and long-term disease (>2 years) were examined using in situ hybridization and immunohistochemistry. IL-4 STAT mRNA could be detected in synovium of patients with short-term and long-term RA. The most intensive expression of IL-4 STAT mRNA could be seen in follicular inflammatory infiltrates. In the synovial lining, both fibroblasts and macrophages expressed IL-4 STAT mRNA. IL-4 STAT and Jak-1 protein was expressed by synoviocytes, and up-regulation could be induced after stimulation with IL-4. Activation of IL-4 STAT was reflected by phosphorylation of IL-4 STAT. The results indicate that IL-4 STAT is involved in key pathomechanisms in RA synovium and that IL-4 STAT-dependent pathways operate in early and late stages of the disease and presumably contribute to inhibitory immune mechanisms in RA synovium.
Arthritis, Rheumatoid↗
Regulation of CS1 fibronectin expression and function by IL-1 in endothelial cells.
VLA-4 is a critical adhesion molecule that regulates mononuclear cell trafficking to sites of inflammation. VCAM-1 is a primary ligand of VLA-4, although alternatively spliced fibronectin (FN) containing the CS1 region (CS1 FN) also binds to VLA-4. CS1 FN is expressed by rheumatoid arthritis (RA) synovial endothelial cells, but the factors that regulate CS1 FN expression are not known. We incubated human umbilical vein endothelial cells (HUVEC) with IL-1 (0.1-10 ng/ml) for 8-48 h and determined total FN and CS1 FN mRNA by Northern blot analysis. Both were constitutively expressed by HUVEC, and IL-1 increased total FN mRNA and the CS1-containing isoform (P < 0.05). IL-1 also increased CS1 FN protein expression on HUVEC as determined by Western blot analysis. An adhesion assay using (51)Cr-labeled Jurkat cells and IL-1-stimulated HUVEC was used to determine if IL-1-induced CS1 FN mediates cell binding. Cyclic CS1 peptide (10 microg/ml) blocked 49 +/- 5% of IL-1-induced Jurkat cell adhesion to HUVEC (P < 0.01), whereas anti-VCAM-1 antibody inhibited binding by only 35 +/- 5% (P < 0.01). CS1 peptide and anti-VCAM antibody treatment were not additive (50 +/- 7% inhibition), and 38 +/- 6% of new VLA-4-mediated adhesion to IL-1-treated HUVEC was due to an increase in CS1 FN. These data show that IL-1 increases CS1 FN expression by HUVEC and increases CS1-mediated cell adhesion. CS1 mimetics might have therapeutic efficacy by blocking recruitment of VLA-4-bearing cells.
Alternative Splicing↗
Expression of sentrin, a novel antiapoptotic molecule, at sites of synovial invasion in rheumatoid arthritis.
OBJECTIVE: Sentrin, a novel antiapoptotic molecule, has been shown to interact with the signal-competent form of Fas/APO-1 and tumor necrosis factor receptor I (TNFRI), and thereby, to protect cells against anti-Fas/APO-1- and TNF-induced cell death. Since reduced apoptosis in the synovial lining is supposed to contribute to synovial hyperplasia in rheumatoid arthritis (RA), we searched for the expression of sentrin-1 messenger RNA (mRNA) in synovium from patients with RA. METHODS: The expression of sentrin-1 mRNA was examined by in situ hybridization on snap-frozen sections of normal and RA synovial tissues as well as on paraffin-embedded RA synovial specimens, including the interface of cartilage-bone and invading synovium. Immunohistochemical double labeling after in situ hybridization was performed to further characterize sentrin-1 mRNA-expressing cells. In addition, quantitative analysis of sentrin-1 mRNA expression in RA synovial fibroblasts (RASF), osteoarthritis synovial fibroblasts (OASF), and normal fibroblasts was performed by quantitative real-time polymerase chain reaction. Expression levels were standardized to the expression of GAPDH. The in vivo maintenance of sentrin expression in RASF aggressively invading human cartilage was explored in the SCID mouse model of RA. RESULTS: A marked expression of sentrin-1 mRNA could be seen in all RA synovial specimens, predominantly in SF of the lining layer and at sites of invasion of RA synovium into cartilage. In normal synovial tissues, no sentrin-1 mRNA was detectable. RASF showed a maximum 32.5-fold (mean +/- SD 14.9 +/- 11.6) increase of sentrin-1 mRNA expression compared with normal fibroblasts and a maximum 31.4-fold (mean +/-SD 14.3 +/- 10.9) increase compared with OASF. When coimplanted with normal human cartilage in the SCID mouse model, invading RASF maintained their sentrin-1 mRNA expression for at least 60 days in vivo. CONCLUSION: The marked expression of sentrin in rheumatoid synovial tissue, but not in normal or OA synovial tissue, may contribute to the modulation of Fas- and TNFR-mediated apoptosis in RA synovium, and thereby extend the lifespan of invasive, cartilage-destructive SF.
Animals↗
Differential expression pattern of membrane-type matrix metalloproteinases in rheumatoid arthritis.
OBJECTIVE: To study the expression of messenger RNA (mRNA) for different membrane-type matrix metalloproteinases (MT-MMPs) and compare their expression pattern in rheumatoid arthritis (RA) and normal synovium. METHODS: Polymerase chain reaction (PCR) with specific primers was performed to analyze the presence of MT1-, MT2-, MT3-, and MT4-MMP in synovial tissue and synovial fibroblasts from 10 patients with RA and 4 subjects without arthritis. In addition, in situ hybridization with digoxigenin-labeled RNA probes was used to investigate the expression pattern of MT-MMPs in the synovium of these subjects. MT-MMP-expressing cells were characterized by immunohistochemical double labeling with anti-CD68 monoclonal antibodies. RESULTS: Reverse transcription-PCR revealed the expression of MT1-, MT2-, MT3-, and MT4-MMP mRNA in all tissues and cell cultures examined. However, in situ hybridization showed considerable differences in the expression pattern of the different MT-MMPs in RA synovium. MT1- and MT3-MMP mRNA were highly expressed in both the lining and the sublining layer, with more intense staining in the lining. Immunohistochemical double labeling demonstrated the presence of mRNA for MT1-MMP in fibroblasts and macrophages, as well as in osteoclast-like cells at sites of bone resorption. Expression of MT3-MMP mRNA was seen in fibroblasts and some macrophages. Expression of MT2- and MT4-MMP was characterized by staining of only a few CD68-negative fibroblasts, and no differences could be found between the lining and sublining. Normal synovial samples showed only limited staining for all MT-MMPs. CONCLUSION: Our results indicate a role for MT1-MMP not only in the matrix degradation by fibroblasts, but also in osteoclast-mediated bone resorption in RA. Given the ability of MT1-MMP to activate MMP-2 and MMP-13, the findings also point to a cooperation between fibroblasts and macrophages in degrading cartilage and bone. While MT3-MMP is also intensely expressed in RA synovium, MT2- and MT4-MMP appear not to be involved in rheumatoid joint destruction.
Arthritis, Rheumatoid↗
Expression of osteopontin messenger RNA and protein in rheumatoid arthritis: effects of osteopontin on the release of collagenase 1 from articular chondrocytes and synovial fibroblasts.
OBJECTIVE: Osteopontin (OPN) is an extracellular matrix protein that has been implicated in the interactions between tumor cells and host matrix, including those involved in invasion and spread of tumor cells. Because joint destruction in rheumatoid arthritis (RA) is mediated by the invasive growth of synovial tissue through its attachment to cartilage, we examined the expression of OPN in the synovia of patients with RA and the effect of OPN on the production of collagenase 1 in rheumatoid synovial fibroblasts and articular chondrocytes. METHODS: The expression of OPN messenger RNA (mRNA) and protein in synovia from 10 RA patients was examined by in situ hybridization and immunohistochemistry. Synovial fibroblasts from RA patients and articular chondrocytes from patients without joint disease were cultured in the presence of various concentrations of OPN, and levels of collagenase 1 in the culture supernatants were measured by enzyme-linked immunosorbent assay. RESULTS: The expression of OPN mRNA and protein was observed in 9 of 10 specimens obtained from patients with RA. OPN was expressed in the synovial lining and sublining layer and at the interface of cartilage and invading synovium. Double labeling revealed that the majority of OPN-expressing cells were positive for the fibroblast-specific enzyme prolyl 4-hydroxylase and negative for the macrophage marker CD68, while only a few, single OPN-expressing cells were positive for CD68 at sites of synovial invasion into cartilage. OPN staining was not observed in lymphocytic infiltrates or leukocyte common antigen (CD45)-positive cells. Three of 3 cultures of human articular chondrocytes secreted detectable basal amounts of collagenase, with a dose-dependent increase upon OPN stimulation, while synovial fibroblast cultures produced much lower levels of collagenase, with only 2 of 4 fibroblast cultures responding in a dose-dependent manner. CONCLUSION: These findings suggest that OPN produced by synovial fibroblasts in the synovial lining layer and at sites of cartilage invasion not only mediates attachment of these cells to cartilage, but also contributes to matrix degradation in RA by stimulating the secretion of collagenase 1 in articular chondrocytes.
Aged↗
Cartilage degradation and invasion by rheumatoid synovial fibroblasts is inhibited by gene transfer of a cell surface-targeted plasmin inhibitor.
OBJECTIVE: Joint destruction in rheumatoid arthritis (RA) is a result of degradation and invasion of the articular cartilage by the pannus tissue. The present study was undertaken to examine the role of the plasminogen activation system in cartilage degradation and invasion by synovial fibroblasts and investigate a novel gene therapeutic approach using a cell surface-targeted plasmin inhibitor (ATF.BPTI). METHODS: Adenoviral vectors were used for gene transfer. The effects of ATF.BPTI gene transfer on RA synovial fibroblast-dependent cartilage degradation were studied in vitro, and cartilage invasion was studied in vivo in the SCID mouse coimplantation model. RESULTS: The results indicate that cartilage matrix degradation by rheumatoid synovial fibroblasts is plasmin mediated and depends on urokinase-type plasminogen activator for activation. Targeting plasmin inhibition to the cell surface of the fibroblasts by gene transfer of a cell surface-binding plasmin inhibitor resulted in a significant reduction of cartilage matrix degradation in vitro and of cartilage invasion in vivo. Compared with uninfected rheumatoid synovial fibroblasts, the mean +/-SEM cartilage degradation in vitro was reduced to 87.9+/-0.9% after LacZ gene transfer versus a reduction to 24.0+/-1.6% after ATF.BPTI gene transfer (P<0.0001). The mean +/- SEM in vivo cartilage invasion score was 3.1+/-0.4 in the control-transduced fibroblasts and 1.8+/-0.4 in the ATF.BPTI-transduced fibroblasts (P<0.05). CONCLUSION: These results indicate a role of the plasminogen activation system in synovial fibroblast-dependent cartilage degradation and invasion in RA, and demonstrate an effective way to inhibit this by gene transfer of a cell surface-targeted plasmin inhibitor.
Activating Transcription Factors↗
Anti-interleukin-1 and anti-CD44 interventions producing significant inhibition of cartilage destruction in an in vitro model of cartilage invasion by rheumatoid arthritis synovial fibroblasts.
OBJECTIVE: To establish an in vitro model for the investigation of destructive processes in rheumatoid arthritis (RA), to study the interaction between fibroblasts, macrophages, and chondrocytes, and to evaluate strategies to inhibit joint destruction in RA. METHODS: Human and bovine chondrocytes cultured in sponges pretreated with native bovine embryonic extracellular matrix produced a cartilaginous matrix reflected by the incorporation of 35S into proteoglycans. The 3-dimensional culture system was optimized for the number of chondrocytes (10(5) cells/sponge), the timing of 35S incorporation (day 21 after chondrocyte isolation), and the medium (20% fetal calf serum). RA synovial fibroblasts (RASF; 10(5)) were added, and the matrix destruction mediated by these RASF was monitored by the release of 35S. The system was modulated by the addition of monocytes (U937 cells), cytokines (interleukin-1beta [IL-1beta] and tumor necrosis factor alpha [TNFalpha]), interleukin-1 receptor antagonist (IL-1Ra), and monoclonal antibodies against IL-1beta and CD44. RESULTS: RASF destroyed the bovine cartilaginous matrix within 2 weeks (days 5-12) and the human cartilaginous matrix within 3 weeks (days 10-18). Compared with the effect of RASF alone (mean +/- SD 948 +/-180 counts per minute/week), the addition of U937 cells (a monocytic cell line), IL-1beta, or TNFalpha to the incubation medium increased the destruction of human cartilaginous matrix by at least 71% up to 90% (ranging from 1,618+/-204 cpm/week to 1,802+/-307 cpm/week). IL-1Ra and anti-IL-1beta monoclonal antibodies reduced the destruction of human matrix by 45% and 35%, respectively; this was partially reversed by the addition of U937 cells. The pretreatment of RASF with anti-CD44 monoclonal antibody (an adhesion molecule and receptor for hyaluronic acid) inhibited the destruction of the cartilaginous matrix by an average of 41% over 3 weeks. CONCLUSION: This model is envisioned to study distinct aspects of human destructive joint diseases under in vitro conditions and to replace and/or supplement animal experiments in basic research and drug testing. Based on the fact that proinflammatory cytokines enhance destruction whereas IL-1Ra and antibodies against IL-1beta and CD44 inhibit the process, it is concluded that anti-IL-1- and anti-CD44-directed therapies may help prevent cartilage destruction in RA.
Animals↗
Expression of osteoclast differentiation factor in rheumatoid arthritis.
OBJECTIVE: To analyze the expression pattern of osteoclast differentiation factor (ODF) and its contribution to osteoclastogenesis in rheumatoid arthritis (RA). METHODS: The expression of ODF was analyzed by reverse transcriptase-polymerase chain reaction (RT-PCR) in RA synovial fibroblasts (RASF) isolated from 7 RA patients and in normal skin fibroblasts. Using RNA probes specific for ODF, in situ hybridization was performed. Immunohistochemical double labeling for CD68 was applied to characterize the ODF-expressing cells. ODF protein and messenger RNA (mRNA) expression by RASF with or without 1,25(OH)2D3 was studied by Western blot analysis and quantitative real-time PCR. In addition, we performed coculture experiments with RASF and normal peripheral blood mononuclear cells with or without 1,25(OH)2D3. RESULTS: By RT-PCR, ODF mRNA expression was found in all RASF investigated, but not in normal skin fibroblasts. In situ hybridization revealed that in RA synovial tissues, ODF mRNA was expressed mainly in the lining layer and at sites where synovium was attached to bone. Immunohistochemical double labeling demonstrated ODF mRNA expression mainly in CD68-fibroblast-like synoviocytes and CD68+ multinucleated osteoclast-like cells. By Western blotting, all RASF expressed ODF protein. However, different levels of ODF expression were found in the RASF from different patients. Interestingly, RASF expressing higher levels of ODF induced a larger number of osteoclast-like cells than did RASF expressing only low levels of ODF. Although 1,25(OH)2D3 did not alter the levels of ODF expression in RASF on either Western blot or quantitative real-time PCR, osteoclastogenesis required the presence of 1,25(OH)2D3. CONCLUSION: The present results suggest that activated RASF, by expressing ODF, play an important role in rheumatoid bone destruction. Moreover, the data provide evidence that RASF not only activate osteoclasts, but also contribute directly to osteoclastogenesis.
Arthritis, Rheumatoid↗
Modulation of fibroblast-mediated cartilage degradation by articular chondrocytes in rheumatoid arthritis.
OBJECTIVE: To determine the role of chondrocytes and factors released from chondrocytes in cartilage destruction by fibroblast-like synoviocytes (FLS) derived from patients with rheumatoid arthritis (RA). METHODS: RA FLS from 2 patients were implanted into SCID mice, together with fresh articular cartilage or with cartilage that had been stored for 24 hours at 4 degrees C or at 37 degrees C. The invasion of the same RA FLS into the fresh and stored cartilage was compared histologically using a semiquantitative scoring system. In addition, we investigated whether protein synthesis in chondrocytes affects the invasion of RA FLS in vitro. A 3-dimensional cartilage-like matrix formed by cultured chondrocytes was labeled with 35S. After formation of the cartilage-like matrix, protein synthesis was blocked with cycloheximide. The invasion of RA FLS from 6 patients into cycloheximide-treated and untreated matrix was assessed by measuring the released radioactivity in coculture with and without interleukin-1beta (IL-1beta) and tumor necrosis factor alpha (TNFalpha). RESULTS: The SCID mouse experiments showed a significant invasion of RA FLS into the cartilage (overall mean score 3.2) but revealed significant differences when the invasion of the same RA FLS into fresh and stored cartilage was compared. RA FLS that were implanted with fresh articular cartilage showed a significantly higher invasiveness than those implanted with pieces of cartilage that had been stored for 24 hours (overall mean score 2.3). Storage at 37 degrees C and 4 degrees C resulted in the same reduction of invasion (35% and 37%, respectively). In the in vitro experiments, RA FLS rapidly destroyed the cartilage-like matrix. Blocking of chondrocyte protein biosynthesis significantly decreased the invasion of RA FLS, as shown by a decreased release of radioactivity. Addition of IL-1beta, but not TNFalpha, to the cocultures partially restored the invasiveness of RA FLS. CONCLUSION: These data underline the value of the SCID mouse in vivo model of rheumatoid cartilage destruction and demonstrate that chondrocytes contribute significantly to the degradation of cartilage by releasing factors that stimulate RA FLS. Among those, IL-1beta-mediated mechanisms might be of particular importance.
Animals↗
Retrotransposable L1 elements expressed in rheumatoid arthritis synovial tissue: association with genomic DNA hypomethylation and influence on gene expression.
OBJECTIVE: Rheumatoid arthritis (RA) is characterized by a progressive destruction of joints by invasive synovial fibroblasts (SF). We searched for retroviral sequences in RA synovial fluid pellets, identified a sequence similar to that of open reading frame 2 (ORF2)/L1 retrotransposable elements, explored the expression of L1 in RA synovial tissues and cultured RA SF, and investigated the link to genomic DNA hypomethylation and the influence of functional L1 on gene expression. METHODS: RA synovial fluid pellets were screened by reverse transcriptase-polymerase chain reaction (RT-PCR) using degenerated pol primers. The sequences were identified by GenBank search. Riboprobes to ORF2/L1 and galectin-3 and antibodies to the ORF1/L1-related p40 protein were used for in situ hybridization and immunohistochemistry of synovial tissues and cultured RA SF. Real-time quantitative RT-PCR was used for detecting ORF1 messenger RNA (mRNA). Since DNA hypomethylation occurs in inflammatory diseases, we incubated cells with the methylation inhibitor 5-aza-2'-deoxycytidine (5-azaC) and compared RA SF and osteoarthritis (OA) SF. L1-negative RA SF were transfected with the functional L1.2 construct, and differential gene expression was analyzed by subtractive hybridization combined with nested PCR. RESULTS: RNA sequences similar to those of ORF2/L1 retrotransposable elements, THE1 transposon, human endogenous retrovirus (ERV)-E, human ERV-HC2, and gibbon ape leukemia virus pol genes were isolated from different RA synovial fluid pellets. In RA synovial tissues, ORF2/L1 transcripts were detected in the sublining layer and at sites of cartilage and bone destruction. Galectin-3 mRNA and L1-related ORF1/ p40 protein showed similar expression patterns. In contrast, OA synovial tissues in situ and cultures in vitro were negative. Real-time quantitative RT-PCR confirmed the presence of ORF1 mRNA in cultured RA SF (30-300-fold the amount in normal SF), demonstrating the existence of a nondegenerated and functional L1 element. In vitro, the majority of RA SF expressed ORF2/L1 mRNA. After incubation of SF with 5-azaC, L1 mRNA appeared in a time- and dose-dependent manner. Compared with OA SF, RA SF were more sensitive to 5-azaC. After transfection of RA SF with a functional L1.2 element, human stress-activated protein kinase 2 delta (SAPK2delta [or SAPK4]), met protooncogene, and galectin-3 binding protein genes were differentially expressed. The transcription of the SAPK2delta gene, favored also by DNA hypomethylation in vitro, was confirmed in RA synovial tissues. CONCLUSION: Taken together, these data suggest that L1 elements and SAPK2delta pathways play a role in the activation of RA SF.
Antigens, Differentiation↗
Gene therapy in osteoarthritis.
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Animals↗
Increased serum levels of non-collagenous matrix proteins (cartilage oligomeric matrix protein and melanoma inhibitory activity) in marathon runners.
OBJECTIVE: Marathon runners have an increased risk of developing joint disease. During and after a 42-km run, elevation of multiple cytokines occurs in the blood, reflecting inflammatory processes. We compared this cytokine response with serum levels of cartilage oligomeric matrix protein (COMP) and melanoma inhibitory activity (MIA), two markers for joint metabolism and/or damage. METHODS: Serum from eight endurance-trained runners was collected shortly before the start of a marathon run, after 31 km, 42 km, 2 h after the end, on the first and on the second morning after the run. For comparison, serum was obtained from 35 healthy controls and 80 patients with knee joint injury, rheumatoid arthritis or osteoarthritis. Serum levels of C-reactive protein (CRP), interleukin-1beta (IL-1beta), interleukin-1 receptor antagonist (IL-1RA), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), soluble interleukin-6 receptor (sIL-6R, gp80), soluble tumor necrosis factor receptor II (sTNFRII, p75), COMP and MIA were measured by ELISA. RESULTS: Compared with healthy controls, the runner's baseline serum levels of TNF-alpha, sIL-6R, COMP and MIA were significantly increased. COMP and MIA levels, higher than the upper normal limits of 5 microg/ml and 6 ng/ml respectively, were found in seven and five of eight runners. The elevated levels of COMP were similar to those found in joint injury or osteoarthritis, and the elevated levels of MIA were comparable to those reported in rheumatoid arthritis. During the run, the serum levels of IL-1RA, IL-6, TNF-alpha and COMP rose significantly, and gradually returned to baseline within 24 h. Only modest changes of CRP, sIL-6R, sTNFRII and MIA occurred during the run. Late elevations of CRP and MIA were observed after 24 and 48 h. The correlation analysis suggests associations between COMP, sIL-6R, TNF-alpha, IL-1RA on one hand and sTNFRII, and MIA and CRP on the other hand. CONCLUSIONS: Elevated baseline levels of COMP and MIA might reflect increased joint matrix turnover and/or damage due to prior extreme physical training. During the run, COMP was increasing possibly due to the severe physical strain on joint structures, associated with the early inflammation. After the run, MIA and CRP increased within 24 h, suggesting a correlation with later inflammatory processes. Thus, our data suggest that COMP and MIA are markers for distinct aspects of joint metabolism and/or damage in both disease and sport.
Adult↗
Activation of synoviocytes.
The evaluation of molecular pathways has revealed various novel insights into rheumatoid arthritis pathophysiology during the past year. In addition, there is an increasing tendency toward analysis not merely of a single mechanism but rather of data addressing a substantial part of the cascade of events leading to cellular activation. Because synovial fibroblasts are key cells involved in joint destruction, this review outlines the events that trigger or inhibit the crucial pathways leading to their aggressive behavior. Major topics include cellular and humoral interactions (frequently modulated by cytokines), intracellular signaling and upregulation of gene transcription, and the deleterious effects on articular homeostasis.
Animals↗