Synovial tissue protease gene expression and joint erosions in early rheumatoid arthritis

Differential regulation of matrix metalloproteinase 2 and matrix metalloproteinase 9 by activated protein C: relevance to inflammation in rheumatoid arthritis

OBJECTIVE

To investigate the in vitro effect of activated protein C (APC), a natural anticoagulant and novel antiinflammatory agent, on the regulation of the gelatinases matrix metalloproteinase 2 (MMP-2) and MMP-9.

METHODS

Synovial fibroblasts and peripheral blood monocytes isolated from patients with rheumatoid arthritis (RA) or osteoarthritis (OA) and Mono Mac6 cells were used in this study. After treatment, cells and culture supernatants were collected for zymography, enzyme-linked immunosorbent assay, reverse transcription-polymerase chain reaction, and Western blot analysis.

RESULTS

Fibroblasts and monocytes from RA patients produced substantially more MMP-9 than did those from OA patients; however, there was no difference in MMP-2 production. The addition of recombinant APC markedly reduced MMP-9 at the gene and protein levels. In contrast, APC up-regulated and activated MMP-2. Using a blocking antibody to the endothelial protein C receptor (EPCR), we showed that the inhibition of MMP-9 by APC was EPCR-dependent. Furthermore, APC directly suppressed the production of tumor necrosis factor (TNF) and the activation of NF-kappaB and MAP kinase p38, and inhibitors of NF-kappaB or p38 reduced the production of MMP-9, suggesting that APC inhibits MMP-9 by blocking TNF, NF-kappaB, and p38. Thus, APC acts on MMP-9 by binding to EPCRs on the cell surface and, subsequently, inhibiting the intracellular activation of the proinflammatory signaling molecules NF-kappaB and p38.

CONCLUSION

APC appears to be the first physiologic agent to inhibit the production of proinflammatory MMP-9, yet increase antiinflammatory MMP-2 activity. Our results provide the initial evidence that APC may be beneficial in the prevention of inflammation and joint destruction in RA.

The ESPOIR cohort: a ten-year follow-up of early arthritis in France: methodology and baseline characteristics of the 813 included patients

OBJECTIVES

The French Society of Rheumatology initiated a large national multicenter, longitudinal and prospective cohort, the so-called "ESPOIR cohort study" in order to set up databases to allow various investigations on diagnosis, prognostic markers, epidemiology, pathogenesis and medico-economic factors in the field of early arthritis and rheumatoid arthritis.

METHODS

Patients were recruited if they had undifferentiated arthritis or rheumatoid arthritis, of less than 6 months disease duration and if they were DMARD and steroids naïve. Patients have then to be followed every 6 months during the first 2 years then every year during at least 10 years. Clinical, biological, radiographic and medico-economic databases have been constituted to fit in the different objectives of the project and more than 20 scientific studies have already been accepted by the scientific committee.

RESULTS

813 patients were included (76.75% were female). The mean age was 48.07+/-12.55 years. The mean delay from the onset of symptoms to referral to the rheumatologist was 74.8+/-76.6 days. Baseline swollen and tender joint counts were 7.19+/-5.37 and 8.43+/-7.01; DAS28 score was 5.11+/-1.31. CRP was abnormal in 38.9% of the patients; 44.2%, 45.8% and 38.8% had respectively IgM rheumatoid factor (RF), IgA RF and anti-CCP antibodies. HLA DRB1*01 or 04 genes were found in 56.7% of them. Finally, 22% of these patients had erosions on hand or feet at baseline.

Studies on the cell-immunosuppressive mechanism of Oridonin from Isodon serra

Distinct effects of Oridonin and Lasiodonin, which were extracted from Isodon serra was compared by the ratio of IC(50) versus EC(50), the therapeutic index. After choosing the more effective one, Oridonin, its immunosuppressive effect and mechanism were investigated using BALB/c mouse splenic lymphocytes both in vitro and in vivo. When murine splenic lymphocytes was incubated with Oridonin, the novel extract effectively suppress the overproduction of the cell stimulated by Concanavalin A in a dose and time-dependent manner. This inhibitive activity was mainly due to interfering DNA replication in G(1) stages and regulating cell cycle and minorly due to decreasing the CD4(+)/CD8(+) lymphocytes level, according to Flow cytometry analyses (FCAS) results. Xylene-induced mouse tumescence model result suggested that Oridonin depressed the murine ear-swelling extent and the level of Interleukin-2 in the blood serum of experimental animals. The exciting results of enzyme-linked immunosorbent assay (ELISA) indicated that Oridonin could inhibit the secretion of Interleukin-2, Interferon-gamma, Interleukin-12p40 and Tumor necrosis factor-alpha in murine splenic lymphocytes. Moreover, the results of reverse transcriptase-polymerase chain reaction (RT-PCR) confirmed that the inhibition was through decreasing the expression level of these cytokines mRNA. Consequently, the results of our research showed that Oridonin suppressed overproduction of murine splenic lymphocytes through interference of DNA replication, regulation of cell cycle and inhibition of cytokine secretion both at protein and mRNA level.

Helicobacter pylori stimulates gastric epithelial cell MMP-1 secretion via CagA-dependent and -independent ERK activation

Because the mechanisms of Helicobacter pylori-induced gastric injury are incompletely understood, we examined the hypothesis that H. pylori induces matrix metalloproteinase-1 (MMP-1) secretion, with potential to disrupt gastric stroma. We further tested the role of CagA, an H. pylori virulence factor, in MMP-1 secretion. Co-incubation of AGS cells with Tx30a, an H. pylori strain lacking the cagA virulence gene, stimulated MMP-1 secretion, confirming cagA-independent secretion. Co-incubation with strain 147C (cagA(+)) resulted in CagA translocation into AGS cells and increased MMP-1 secretion relative to Tx30a. Transfection of cells with the recombinant 147C cagA gene also induced MMP-1 secretion, indicating that CagA can independently stimulate MMP-1 secretion. Co-incubation with strain 147A, containing a cagA gene that lacks an EPIYA tyrosine phosphorylation motif, as well as transfection with 147A cagA, yielded an MMP-1 secretion intermediate between no treatment and 147C, indicating that CagA tyrosine phosphorylation regulates cellular signaling in this model system. H. pylori induced activation of the MAP kinase ERK, with CagA-independent (early) and dependent (later) components. MEK inhibitors UO126 and PD98059 inhibited both CagA-independent and -dependent MMP-1 secretion, whereas p38 inhibition enhanced MMP-1 secretion and ERK activation, suggesting p38 negative regulation of MMP-1 and ERK. These data indicate H. pylori effects on host epithelial MMP-1 expression via ERK, with p38 playing a potential regulatory role.

Crucial role of macrophages in matrix metalloproteinase-mediated cartilage destruction during experimental osteoarthritis: involvement of matrix metalloproteinase 3

OBJECTIVE

To explore the involvement of synovial macrophages in early cartilage damage in osteoarthritis (OA), and to identify the role of matrix metalloproteinase 3 (MMP-3) in the pathology of early and late OA.

METHODS

The role of synovial macrophages in MMP-mediated damage in OA was studied by depleting synovial macrophages prior to elicitation of a collagenase-induced instability model of OA. The expression of MMP in synovium and cartilage was monitored using TaqMan analysis. In spontaneous and induced OA, cartilage pathology was scored in MMP-3-knockout mice and control mice, by histologic assessment and VDIPEN staining.

RESULTS

On day 14 following induction of OA, MMP-mediated neoepitopes were detected in cartilage from mice with mild experimental OA (mean +/- SD positively stained surface area 20 +/- 3.2%). Remarkably, by depleting synovial macrophages prior to induction of OA, the generation of MMP-induced neoepitopes was largely prevented (mean +/- SD positively stained surface area 5 +/- 1%; P< 0.001), indicating an important role for synovial macrophages in the occurrence of MMP-mediated cartilage damage. We observed a strong decrease in MMP-3 and MMP-9 expression in synovial but not cartilage tissue in macrophage-depleted joints. Among 2-year-old mice, spontaneous OA-like changes in the lining layer were significantly decreased in MMP-3-knockout mice compared with control mice. Even more striking was the 67% reduction in the occurrence of severe cartilage damage in MMP-3-knockout mice. In addition, MMP-mediated VDIPEN expression was significantly decreased, indicating reduced MMP-mediated cartilage breakdown.

CONCLUSION

The results of this study prove that MMP-3 is involved in the generation of severe cartilage damage in murine OA. Synovial macrophages are crucial in early MMP activity and appear to mediate MMP production in synovium rather than cartilage.

Use of molecular imaging to quantify response to IKK-2 inhibitor treatment in murine arthritis

OBJECTIVE

The NF-kappaB signaling pathway promotes the immune response in rheumatoid arthritis (RA) and in rodent models of RA. NF-kappaB activity is regulated by the IKK-2 kinase during inflammatory responses. To elucidate how IKK-2 inhibition suppresses disease development, we used a combination of in vivo imaging, transcription profiling, and histopathology technologies to study mice with antibody-induced arthritis.

METHODS

ML120B, a potent, small molecule inhibitor of IKK-2, was administered to arthritic animals, and disease activity was monitored. NF-kappaB activity in diseased joints was quantified by in vivo imaging. Quantitative reverse transcriptase-polymerase chain reaction was used to evaluate gene expression in joints. Protease-activated near-infrared fluorescence (NIRF) in vivo imaging was applied to assess the amounts of active proteases in the joints.

RESULTS

Oral administration of ML120B suppressed both clinical and histopathologic manifestations of disease. In vivo imaging demonstrated that NF-kappaB activity in inflamed arthritic paws was inhibited by ML120B, resulting in significant suppression of multiple genes in the NF-kappaB pathway, i.e., KC, epithelial neutrophil-activating peptide 78, JE, intercellular adhesion molecule 1, CD3, CD68, tumor necrosis factor alpha, interleukin-1beta, interleukin-6, inducible nitric oxide synthase, cyclooxygenase 2, matrix metalloproteinase 3, cathepsin B, and cathepsin K. NIRF in vivo imaging demonstrated that ML120B treatment dramatically reduced the amount of active proteases in the joints.

CONCLUSION

Our data demonstrate that IKK-2 inhibition in the murine model of antibody-induced arthritis suppresses both inflammation and joint destruction. In addition, this study highlights how gene expression profiling can facilitate the identification of surrogate biomarkers of disease activity and treatment response in an experimental model of arthritis.

The synovial membrane as a prognostic tool in rheumatoid arthritis

The ability to effectively treat patients with rheumatoid arthritis (RA) has become increasingly feasible with the use of powerful treatment regimens early on in the disease. The use of such regimens has, however, created a pressing requirement for better prognostic markers to allow the targeting of these treatments to those most at need, hence minimizing expense and toxicity. As the synovial membrane has been ever more recognised as the primary pathogenetic site in RA its role as a prognostic indicator has been explored. As yet no reliable single prognostic marker has been identified. This article discusses the range of pathological variables already examined and those markers holding most potential.

Vascular endothelial growth factor and matrix metalloproteinase-2 expedite formation of endometriosis in the early stage ICR mouse model

OBJECTIVE

To establish a mouse model for endometriosis and to evaluate roles of vascular endothelial growth factor (VEGF) and matrix metalloproteinase-2 (MMP-2) in the formation of disease.

DESIGN

Experimental laboratory study.

SETTING

A women's hospital in China.

PATIENT(S) AND ANIMAL(S)

Ten women with endometriosis and 10 control women, as well as ICR mice.

INTERVENTION(S)

Endometrial fragments were transplanted in the peritoneal cavities of mice at minilaparotomy. Transplants were observed and then removed for the assessment of morphology and immunohistochemical staining of VEGF and MMP-2.

MAIN OUTCOME MEASURE(S)

Observation of transplants, expression of VEGF and MMP-2.

RESULT(S)

On days 1 and 2, glandular and stromal cells were viable at the margins of transplants. On day 3, the transplants were surrounded by mesothelial cells, and the endometrial glands and stromal cells were clearly viable at the interface. The scores of VEGF and MMP-2 of viable glandular cells of transplants were increased compared with the ones before transplantation. The scores of VEGF and MMP-2 of transplants from women with endometriosis were higher than those of control women.

CONCLUSION(S)

Endometrial transplants from the patients with endometriosis express more VEGF and MMP-2 than endometrium in control women, suggesting that VEGF and MMP-2 may expedite the formation of endometriosis in its early stage.

The -675 4G/5G plasminogen activator inhibitor-1 promoter polymorphism in house dust mite-sensitive allergic asthma patients

BACKGROUND

Plasminogen activator inhibitor (PAI)-1 plays an important role in inflammation and tissue remodeling. Recently, the -675 4G/5G PAI-1 polymorphism has been linked with asthma.

OBJECTIVE

This study was undertaken to evaluate associations of the -675 4G/5G PAI-1 polymorphism with functional and immunologic parameters of newly diagnosed house dust mite-sensitive allergic asthmatics (HDM-AAs).

METHODS

This study was performed in 127 HDM-AAs, who responded with at least 20% fall of forced expiratory volume during the first second (FEV(1)) to a bronchial challenge with Dermatophagoides pteronyssinus allergen and during the follow up observation fulfilled GINA criteria for mild-moderate asthma. About 89 healthy control nonatopic subjects (HCs) were used as controls.

RESULTS

The frequency of 4G allele was greater in HDM-AAs (0.69; 95% CI: 0.62-0.76) than in HCs (0.55; 95% CI: 0.48-0.62; P = 0.0034). The PAI-1 polymorphism was associated with an increased risk of HDM-AA; adjusted for sex and age odds ratio was 2.62; (95% CI: 1.16-5.92) for 4G/5G genotype and 3.48 (95% CI: 1.54-7.89) for 4G/4G genotype compared with 5G/5G genotype. Total serum immunoglobulin E (tsIgE) level in 4G/4G homozygotes (557 +/- 343 kU/l) was significantly greater than in 5G/5G homozygotes (241 +/- 288 kU/l; P < 0.001). Both nonspecific and allergen-specific bronchial reactivities were greater in 4G/4G homozygotes than in 5G/5G homozygotes. 4G/4G genotype was associated with significantly higher morning plasma PAI-1 concentration in HDM-AAs and HCs. Morning plasma PAI-1 concentration correlated significantly with log(PC20) (r = -0.39; P = 0.0001) and with log(tsIgE) (r = 0.247; P = 0.0117).

CONCLUSION

These results support the hypothesis linking the 4G/4G PAI-1 genotype with an increased risk of allergic asthma, bronchial hyperreactivity, and increased tsIgE levels.

Distinct immunosuppressive effect by Isodon serra extracts

Distinct effect of ent-Kaurene Diterpenoids from Isodon serra on abnormal proliferation of murine lymphocytes was examined with MTT assay and Flow Cytometry Analyses (FCAS). After choosing the most appropriate monomer from these Diterpenoids, we introduced mouse tumescence model to investigate whether it could impact cytokine production in vivo with ELISA assay. The result of MTT assay showed that four ent-Kaurene Diterpenoids could effectively suppress the murine splenic T lymphocytes overproduction stimulated by Concanavalin A, while inhibitive effect was softer on normal sleep lymphocytes than the stimulated ones. Among four ent-Kaurene Diterpenoids, Enmein was the most sensitive one with IC50/EC50 equaling to 1.55. This inhibitive activity was due to interfering DNA replication in G1-S stage and to regulating cell cycle according to flow cytometry analyses (FCAS) result. Xylene-induced mouse tumescence model result further suggested that Enmein depressed the murine ear swelling extent and the level of Interleukin-2 in blood serum in a dose-dependent manner. In conclusion, it demonstrated that four ent-Kaurene Diterpenoids from I. serra had distinct immunosuppressive effect in vitro and in vivo systems, which primarily differentiated Enmein from the others. The experimental results provided insight into a potential immunosuppressive action of Enmein as a promising drug, though profound mechanism remained to be further studied.

Temporospatial expression of matrix metalloproteinases and tissue inhibitors of matrix metalloproteinases in mouse antigen-induced arthritis

Several lines of evidence speak for an important role of matrix metalloproteinases (MMPs) in the development of progressive joint destruction. To better understand the role of MMPs and their tissue inhibitors (TIMPs) in this process, we have used the antigen-induced arthritis model to study the temporospatial expression of several MMPs and TIMPs during the progression of arthritis. Arthritis was induced by a single intra-articular injection of methylated bovine serum albumin (mBSA) into one or both knee joints of adult mice previously immunised against mBSA. Samples were collected at 3, 7, 21 and 42 days after induction of arthritis for histology and RNA extraction, and analysed by Northern hybridisation, histochemistry and immunohistochemistry for production of several MMPs and TIMPs -1, -2 and -3. A systematic analysis of MMP and TIMP mRNA levels in mouse knee joints demonstrated a general upregulation of both MMPs and TIMPs during progression of arthritis. Upregulation of MMP-9, -13 and -14 coincided with the advancement of cartilage degeneration, but the expression patterns of MMP-9 and -13 also followed the course of synovial inflammation. TIMPs were steadily upregulated throughout the examination period. Immunohistochemical localisation of MMPs and TIMPs suggested the synovium to be the major source of MMP and TIMP production in arthritis, although articular cartilage chondrocytes also showed an increased production of both MMPs and TIMPs.

Hemoglobin stimulates the expression of matrix metalloproteinases, MMP-2 and MMP-9 by synovial cells: a possible cause of joint damage after intra-articular hemorrhage

Intra-articular bleeding causes degradation of articular cartilage leading to joint disorders, but the mechanisms is not well understood. The present study examined the effect of hemoglobin on the ability of synovial tissues to produce plasminogen activators and matrix metalloproteinases that play important roles in the degradation of articular cartilage. Human Hb added to primary cultures of human knee synovial cells markedly increased fibrinolytic activity and gelatinolytic activity. The fibrinolytic activity was due to an increase in uPA activity. Western blot analysis and gelatin zymography indicated that the increased gelatinolytic activity was due to increased MMP-2 and -9. In order to know whether the effect of Hb on cultured synovial tissue is also true in in vivo system or not, rabbit hemoglobin was injected into rabbit knee joints. Coinciding with in vitro study, hemoglobin elicited considerable increase in fibrinolytic and gelatinolytic activity. The level of proteoglycan fragments in the hemoglobin-treated joint fluid was significantly elevated, indicating cartilage matrix degradation. Cartilage damage after hemoglobin treatment was also confirmed by histological study. These findings suggest that hemoglobin stimulates the secretion of uPA, MMP-2 and MMP-9 by synovial tissues, and raise a possible role of hemoglobin in joint damage after intra-articular bleeding.

Expression of CD147 on monocytes/macrophages in rheumatoid arthritis: its potential role in monocyte accumulation and matrix metalloproteinase production

Monocytes/macrophages play an important role in rheumatoid arthritis (RA) pathogenesis. They can activate fibroblasts through many molecules, including IL-1 and tumor necrosis factor-alpha, but there have been very few reports on the role of CD147 in RA. In our study, the results of flow cytometry reveal that the mean fluorescence intensity (MFI) of CD147 expression on CD14+ monocytes of peripheral blood from RA patients was higher than that in normal control and ankylosing spondylitis (AS) patients. The MFI of CD147 expression on the CD14+ monocytes in RA synovial fluid was higher than that in RA peripheral blood. Immunohistochemical staining shows that CD147 expression in RA synovium correlated with matrix metalloproteinase (MMP)-1 expression. A double immunofluorescent assay shows that CD147 was expressed on CD68+ cells in RA synovium. The potential role of CD147 in cyclophilin A (CyPA)-mediated cell migration was studied using a chemotaxis assay in vitro and it was found that the addition of anti-CD147 antibody or a CD147 antagonistic peptide significantly decreased the chemotactic index of the mononuclear cells. The role of CD147 in MMP production and cell invasion in vitro were studied through the co-culture of human CD14+ monocytes or monocytic line THP-1 cells and human fibroblasts, as well as by gel zymography and an invasion assay. Significantly elevated release and activation of MMP-9 and/or MMP-2 were seen in the co-culture of human monocytes/THP-1 cells and fibroblasts compared with cultures of the cells alone. An increased number of cells invading through the filters in the invasion assays was also observed in the co-cultured cells. The addition of CD147 antagonistic peptide had some inhibitory effect, not only on MMP production but also on cell invasion in the co-culture. Our study demonstrates that the increased expression of CD147 on monocytes/macrophages in RA may be responsible for elevated MMP secretion, cell invasion and CyPA-mediated cell migration into the joints, all of which may contribute to the cartilage and bone destruction of RA. These findings, together with a better understanding of CD147, CyPA and RA, will help in the development of innovative therapeutic interventions for RA.

Characterization of histopathology and gene-expression profiles of synovitis in early rheumatoid arthritis using targeted biopsy specimens

The disease category of early rheumatoid arthritis (RA) has been limited with respect to clinical criteria. Pathological manifestations of synovitis in patients whose disease is clinically classified as early RA seem to be heterogeneous, with regular variations. To clarify the relation between the molecular and histopathological features of the synovitis, we analyzed gene-expression profiles in the synovial lining tissues to correlate them with histopathological features. Synovial tissues were obtained from knee joints of 12 patients with early RA by targeted biopsy under arthroscopy. Surgical specimens of long-standing RA (from four patients) were examined as positive controls. Each histopathological parameter characteristic of rheumatoid synovitis in synovial tissues was scored under light microscopy. Total RNAs from synovial lining tissues were obtained from the specimens selected by laser capture microdissection and the mRNAs were amplified by bacteriophage T7 RNA polymerase. Their cDNAs were analyzed in a cDNA microarray with 23,040 cDNAs, and the levels of gene expression in multilayered lining tissues, compared with those of normal-like lining tissues in specimens from the same person, were determined to estimate gene-expression profiles characteristic of the synovial proliferative lesions in each case. Based on cluster analysis of all cases, gene-expression profiles in the lesions in early RA fell into two groups. The groups had different expression levels of genes critical for proliferative inflammation, including those encoding cytokines, adhesion molecules, and extracellular matrices. One group resembled synovitis in long-standing RA and had high scores for some histopathological features – involving accumulations of lymphocytes and plasma cells – but not for other features. Possible differences in the histopathogenesis and prognosis of synovitis between the two groups are discussed in relation to the candidate genes and histopathology.

Matrix metalloproteinase secretion by gastric epithelial cells is regulated by E prostaglandins and MAPKs

Because matrix metalloproteinases (MMPs) play roles in inflammatory tissue injury, we asked whether MMP secretion by gastric epithelial cells may contribute to gastric injury in response to signals involved in Helicobacter pylori-induced inflammation and/or cyclooxygenase inhibition. Tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, and epidermal growth factor (EGF) stimulated gastric cell MMP-1 secretion, indicating that MMP-1 secretion occurs in inflammatory as well as non-inflammatory situations. MMP-1 secretion required activation of the MAPK Erk and subsequent protein synthesis but was down-regulated by the alternate MAPK, p38. In contrast, secretion of MMP-13 was stimulated by TNF-alpha/IL-1beta but not EGF and was Erk-independent and mediated by p38. MMP-13 secretion was more rapid (peak, 6 h) than MMP-1 (peak > or =30 h) and only partly depended on protein synthesis, suggesting initial release of a pre-existing MMP-13 pool. Therefore, MMP-1 and MMP-13 secretion are differentially regulated by MAPKs. MMP-1 secretion was regulated by E prostaglandins (PGEs) in an Erk-dependent manner. PGEs enhanced Erk activation and MMP-1 secretion in response to EGF but inhibited Erk and MMP-1 when TNF-alpha and IL-1beta were the stimuli, indicating that the effects of PGEs on gastric cell responses are context-dependent. These data show that secretion of MMPs is differentially regulated by MAPKs and suggest mechanisms through which H. pylori infection and/or cyclooxygenase inhibition may induce epithelial cell signaling to contribute to gastric ulcerogenesis.

In vivo imaging of protease activity in arthritis: A novel approach for monitoring treatment response

OBJECTIVE

Sensitive noninvasive strategies for monitoring treatment response in rheumatoid arthritis (RA) would be valuable for facilitating appropriate therapy and dosing, evaluating clinical outcome, and developing more effective drugs. Because different proteases are highly up-regulated in RA and contribute significantly to joint destruction, in the present study we investigated whether such enzymes are suitable in vivo imaging biomarkers for early evaluation of treatment response in a murine model of RA.

METHODS

Using a protease-activated near-infrared fluorescence (NIRF) imaging "smart" probe, we examined the presence and distribution of fluorescence in arthritic joints of mice with collagen-induced arthritis by both noninvasive fluorescence imaging and histology. Proteases that target the Lys-Lys cleavage site, including cathepsin B, activate probe fluorescence. Treatment monitoring data were obtained following methotrexate (MTX) therapy.

RESULTS

Twenty-four hours after intravenous injection of the protease sensor, affected toes and paws of arthritic mice showed significantly higher fluorescence intensity than did toes and paws of healthy mice. Fluorescence from the protease probe and cathepsin B antibody histologic staining were localized in the vast majority of cells in the inflamed synovium. In arthritic animals treated with MTX (35 mg of MTX/kg 48 hours prior to probe injection), a significantly lower fluorescent signal (inflamed paws 50%, inflamed toes 70%) was observed as compared with untreated arthritic animals.

CONCLUSION

Protease-activated NIRF probes are sensitive means of imaging the presence of target enzymes in arthritic joints and can be used for early monitoring of treatment response to antirheumatic drugs such as MTX.

Local expression of the serum amyloid A and formyl peptide receptor-like 1 genes in synovial tissue is associated with matrix metalloproteinase production in patients with inflammatory arthritis

OBJECTIVE

To evaluate the regulation of acute-phase serum amyloid A (A-SAA) production in inflamed synovial tissue, and to elucidate a possible pathophysiologic role in the induction of matrix metalloproteinase (MMP) release by fibroblast-like synoviocytes (FLS).

METHODS

Synovial tissue samples were obtained by arthroscopic biopsy from the knee joints of patients with inflammatory arthritis. Primary cultures of FLS from patients with rheumatoid arthritis (RA), psoriatic arthritis, sarcoid arthritis, and undifferentiated arthritis were established. Total RNA was extracted from FLS and analyzed by reverse transcription-polymerase chain reaction (PCR) using specific primers for A-SAA and formyl peptide receptor-like 1 (FPRL1), an A-SAA receptor. Southern blot analysis confirmed the PCR products generated. Immunohistochemical analysis demonstrated the expression of A-SAA protein production by several synovial cell populations, and immunofluorescence analysis confirmed A-SAA colocalization with the macrophage marker CD68. Primary FLS cultures stimulated with recombinant human A-SAA resulted in dose-dependent MMP-1 and MMP-3 production, as measured by an enzyme-linked immunosorbent assay.

RESULTS

A-SAA messenger RNA (mRNA) and FPRL1 mRNA were present in FLS, macrophages, and endothelial cells isolated from the synovial tissue of patients with RA and other categories of inflammatory arthritis. A-SAA expression was regulated by proinflammatory cytokines and occurred in association with FPRL1 expression in FLS and endothelial cells, which is consistent with a biologic role at the sites of inflammation. Recombinant human A-SAA induced both MMP-1 and MMP-3 secretion by FLS. The mean fold increases in A-SAA-induced MMP-1 and MMP-3 production were 2.6 and 10.6, respectively, compared with 7.6-fold and 41.9-fold increases in interleukin-1 beta-induced MMP-1 and MMP-3 production.

CONCLUSION

The up-regulation of the A-SAA and FPRL1 genes in inflamed synovial tissue suggests an important role in the pathophysiology of inflammatory arthritis. A-SAA induces the production of MMPs. Therapeutic targeting of A-SAA, or FPRL1, may modulate pathophysiologic pathways that are associated with matrix degradation in patients with RA and other forms of progressive inflammatory arthritis.

Increased synovial tissue NF-kappa B1 expression at sites adjacent to the cartilage-pannus junction in rheumatoid arthritis

OBJECTIVE

To compare the expression of the Rel/NF-kappa B subunits, NF-kappa B1 (p50) and RelA (p65), in paired synovial tissue samples selected from sites adjacent to and remote from the cartilage-pannus junction (CPJ) in patients with inflammatory arthritis.

METHODS

Synovial tissue was selected at arthroscopy from sites adjacent to the CPJ and from the suprapatellar pouch of patients who were referred to an early arthritis clinic. Tissue samples from patients with osteoarthritis (OA) undergoing knee arthroplasty were also studied. Rel/NF-kappa B subunit activation and expression were measured by electrophoretic mobility shift assay and supershift analyses and by immunohistochemistry.

RESULTS

Tissue samples were obtained from 10 patients with rheumatoid arthritis (RA), 7 with a seronegative arthropathy (SnA), and 6 with OA. Rel/NF-kappa B was abundantly expressed in all samples. In both RA and SnA synovial tissue, the absolute number of NF-kappa B1+ cells at the CPJ was significantly higher than at non-CPJ sites (P = 0.006 and P = 0.02, respectively). The proportion of cells expressing NF-kappa B1 was also significantly higher at the CPJ compared with non-CPJ sites (P = 0.003 in RA, P = 0.009 in SnA). The numbers of RelA+ cells were consistently lower throughout. In RA synovial tissue, but not in SnA synovial tissue, both the absolute number and the proportion of RelA+ cells were significantly higher at the CPJ than at non-CPJ sites (P = 0.003 and P = 0.01, respectively). In OA synovial tissue, the numbers of cells expressing NF-kappa B1 and RelA were similar to those observed at the non-CPJ sites in all inflammatory tissues studied.

CONCLUSION

In this study of early inflammatory arthritis, expression of NF-kappa B1 in synovial tissue was highest at sites most likely to be associated with joint erosion. These observations are consistent with a critical role of NF-kappa B1 in joint destruction, and support the rationale for specific therapeutic inhibition of NF-kappa B in RA.

The plasmin system in airway remodeling

Recent studies suggest that the plasmin system plays an active role in tissue remodeling. Plasmin degrades the extracellular matrix (ECM), either directly removing glycoproteins from ECM or by activating matrix metalloproteinases (MMPs). PAI-1 blocking MMPs may prevent ECM degradation, but inhibiting fibrinolysis leads to fibrin accumulation and fibrosis. Components of the plasmin system including tissue plasminogen activator (t-PA), urokinase plasminogen activator (u-PA), and plasminogen activator inhibitors PAI-1 and PAI-2 are synthesised by airway cells, and inflammatory mediators affect their expression. The plasmin system, in turn, actively influences the production of inflammatory mediators and growth factors, extending pathological structural changes in the airway. Modulation of the plasmin system might be a new pharmacological strategy that could inhibit the development of airway remodeling.

Association of a specific haplotype across the genes MMP1 and MMP3 with radiographic joint destruction in rheumatoid arthritis

The genetic background of rheumatoid arthritis (RA) is only partly understood, and several genes seem to be involved. The matrix metalloproteinases MMP1 (interstitial collagenase) and MMP3 (stromelysin 1) are thought to be important in destructive joint changes seen in RA. In the present study, functional relevant promoter polymorphisms of MMP1 and MMP3 were genotyped in 308 patients and in 110 controls, to test whether the polymorphisms contribute to the severity of the disease measured by radiographic progression of joint destruction. For comparison, the shared epitope of HLA DR4 and DR1 (SE) was determined by polymerase chain reaction. There was no association of MMP polymorphisms with susceptibility to RA. However, a strong linkage disequilibrium was observed between the 1G/2G (MMP1) and the 5A/6A (MMP3) polymorphisms (P << 10^-6; linkage disequilibrium index D' = 0.46). In factorial regression, the degree of radiographic joint destruction correlated significantly with the 1G-5A haplotype (P = 0.0001) and the interaction term 'estimated number of 1G-5A haplotypes × duration of disease' (P = 0.0007). This association was phasic, indicating that possession of the 1G-5A haplotype has a protective effect over a period of about 15 years of RA, but might be associated with a more pronounced radiographic progression later on. Similar results were also found with the 1G allele of MMP1 alone (P = 0.015) and with the interaction term 'estimated number of 1G alleles × duration of disease' (P = 0.014). The correlation of SE with the Ratingen score was comparable (0.044). The regression model of MMP haplotypes explained 35% of the variance of the radiographic score, whereas the SE explained 29%. The 1G-5A haplotype across the closely linked MMP1 and MMP3 gene loci is a newly described genetic factor strongly associated with the progression of joint damage in RA. Our findings suggest that there are haplotypes in a MMP cluster region that modify the joint destruction in RA in a phasic manner.

Cyclooxygenase-2-derived E prostaglandins down-regulate matrix metalloproteinase-1 expression in fibroblast-like synoviocytes via inhibition of extracellular signal-regulated kinase activation

We examined the regulation of matrix metalloproteinase (MMP) production by mitogen-activated protein kinases and cyclooxygenases (COXs) in fibroblast-like synoviocytes (FLSCs). IL-1beta and TNF-alpha stimulated FLSC extracellular signal-regulated kinase (ERK) activation as well as MMP-1 and -13 release. Pharmacologic inhibitors of ERK inhibited MMP-1, but not MMP-13 expression. Whereas millimolar salicylates inhibited both ERK and MMP-1, nonsalicylate COX and selective COX-2 inhibitors enhanced stimulated MMP-1 release. Addition of exogenous PGE(1) or PGE(2) inhibited MMP-1, reversed the effects of COX inhibitors, and inhibited ERK activation, suggesting that COX-2 activity tonically inhibits MMP-1 production via ERK inhibition by E PGs. Exposure of FLSCs to nonselective COX and selective COX-2 inhibitors in the absence of stimulation resulted in up-regulation of MMP-1 expression in an ERK-dependent manner. Moreover, COX inhibition sufficient to reduce PGE levels increased ERK activity. Our data indicate that: 1) ERK activation mediates MMP-1 but not MMP-13 release from FLSCs, 2) COX-2-derived E PGs inhibit MMP-1 release from FLSCs via inhibition of ERK, and 3) COX inhibitors, by attenuating PGE inhibition of ERK, enhance the release of MMP-1 by FLSC.

Regulation of endometrial stromal cell matrix metalloproteinase activity and invasiveness by interleukin-8

OBJECTIVE

To evaluate the effect of interleukin-8 (IL-8) on endometrial stromal cell metalloproteinase (MMP) activity and invasiveness.

DESIGN

Experimental laboratory study.

SETTING

University medical center.

PATIENT(S)

Reproductive age women without endometriosis.

INTERVENTION(S)

Endometrial stromal cells were grown in culture and treated with recombinant IL-8 (0.0001-10 ng/mL) for 24 to 48 hours. Supernatants were collected for soluble assay of collagenase activity and gelatin zymography. Endometrial stromal cells were plated on 8-microm pore membranes coated with Matrigel or human simple matrix and treated with IL-8 for 48 hours.

MAIN OUTCOME MEASURE(S)

Collagenase activity and MMP2 and 9 activity of control vs. IL-8 treated endometrial cells, and number of endometrial cells that invade through Matrigel or human simple matrix.

RESULT(S)

Collagenase activity in cells treated with IL-8 (1-10 ng/mL) was higher than in control cells. On gelatin zymograms, MMP2 and MMP9 activity of endometrial stromal cells was stimulated by IL-8 treatment (1-10 ng/mL). The number of cells that invaded the Matrigel or human simple matrix was 1.7-fold higher in the group treated with 10 ng/mL of IL-8 compared with the control group.

CONCLUSION(S)

IL-8 increases MMP activity and invasive capability of endometrial stromal cells in culture; IL-8 may be involved in the pathogenesis of endometriosis and menstrual physiology.

Involvement of matrix metalloproteinases and their inhibitors in peripheral synovitis and down-regulation by tumor necrosis factor ? blockade in spondylarthropathy

OBJECTIVE

To investigate the role of matrix metalloproteinases (MMPs) and tissue inhibitors of matrix metalloproteinases (TIMPs) in spondylarthropathy (SpA) synovitis.

METHODS

Paired samples of synovial biopsy tissue as well as serum and synovial fluid (SF) from 41 patients with SpA and 20 patients with rheumatoid arthritis (RA) and serum samples from 20 healthy controls were analyzed by immunohistochemistry and enzyme-linked immunosorbent assay for the presence of MMPs 1, 2, 3, and 9 and TIMPs 1 and 2. In addition, sera from 16 patients with ankylosing spondylitis (AS) and peripheral synovitis and 17 patients with AS and exclusively axial involvement were analyzed. An additional cohort of SpA patients was analyzed at baseline and after 12 weeks of infliximab treatment.

RESULTS

Staining for MMPs and TIMPs showed a cellular and interstitial pattern in the synovial lining and sublining layers that was similar between the RA and SpA patients. Involvement of MMPs and TIMPs in SpA synovitis was suggested by the correlation with cellular infiltration, vascularization, and cartilage degradation. Higher serum levels of MMPs 3 and 9 were revealed in SpA and RA patients as compared with healthy controls. Production of MMP-3, but not MMP-9, in the serum reflected the presence of peripheral synovitis, as indicated by 1) the correlation between serum levels, SF levels (which were 1,000-fold higher than the serum levels), and synovial expression of MMP-3, 2) the increased levels of MMP-3 in AS patients with peripheral disease and not exclusively axial involvement, and 3) the correlation of serum and SF MMP-3 with parameters of synovial, but not systemic, inflammation. The modulation of the MMP/TIMP system by tumor necrosis factor alpha (TNFalpha) blockade was confirmed by the down-regulation of all MMPs and TIMPs in the synovium and a pronounced and rapid decrease of serum MMP-3.

CONCLUSION

MMPs and TIMPs are highly expressed in SpA synovitis and mirror both the inflammatory and tissue-remodeling aspects of the local disease process. Serum MMP-3, originating from the inflamed joint, represents a valuable biomarker for peripheral synovitis. Modulation of the MMP/TIMP system by infliximab could contribute to the antiinflammatory and tissue-remodeling effects of TNFalpha blockade in SpA.

Quantitative biomarker analysis of synovial gene expression by real-time PCR

Synovial biomarker analysis in rheumatoid arthritis can be used to evaluate drug effect in clinical trials of novel therapeutic agents. Previous studies of synovial gene expression for these studies have mainly relied on histological methods including immunohistochemistry and in situ hybridization. To increase the reliability of mRNA measurements on small synovial tissue samples, we developed and validated real time quantitative PCR (Q-PCR) methods on biopsy specimens. RNA was isolated from synovial tissue and cDNA was prepared. Cell-based standards were prepared from mitogen-stimulated peripheral blood mononuclear cells. Real time PCR was performed using TaqMan chemistry to quantify gene expression relative to the cell-based standard. Application of the cellular standard curve method markedly reduced intra- and inter-assay variability and corrected amplification efficiency errors compared with the C(t) method. The inter-assay coefficient of variation was less than 25% over time. Q-PCR methods were validated by demonstrating increased expression of IL-1beta and IL-6 expression in rheumatoid arthritis synovial samples compared with osteoarthritis synovium. Based on determinations of sampling error and coefficient of variation, twofold differences in gene expression in serial biopsies can be detected by assaying approximately six synovial tissue biopsies from 8 to 10 patients. These data indicate that Q-PCR is a reliable method for determining relative gene expression in small synovial tissue specimens. The technique can potentially be used in serial biopsy studies to provide insights into mechanism of action and therapeutic effect of new anti-inflammatory agents.

Molecular regulation of human cathepsin B: implication in pathologies

Cathepsin B is a papain-family cysteine protease that is normally located in lysosomes, where it is involved in the turnover of proteins and plays various roles in maintaining the normal metabolism of cells. This protease has been implicated in pathological conditions, e.g., tumor progression and arthritis. In disease conditions, increases in the expression of cathepsin B occur at both the gene and protein levels. At the gene level, the altered expression results from gene amplification, elevated transcription, use of alternative promoters and alternative splicing. These molecular changes lead to increased cathepsin B protein levels and in turn redistribution, secretion and increased activity. Here we focus on the molecular regulation of cathepsin B and attendant implications for tumor progression and arthritis. The potential of cathepsin B as a therapeutic target is also discussed.

Comparison of synovial tissues from the knee joints and the small joints of rheumatoid arthritis patients: Implications for pathogenesis and evaluation of treatment

OBJECTIVE

Serial synovial biopsy samples are increasingly being used for the evaluation of novel therapies for rheumatoid arthritis (RA). Most studies have used tissues from knee biopsies, but technical improvements have made serial small joint arthroscopy feasible as well. Theoretically, there could be differences in the features of synovial inflammation between various joints as a result of mechanical factors, differences in innervation, and other factors. We therefore undertook this study to compare the cell infiltrate in paired synovial biopsy samples from inflamed knee joints and paired inflamed small joints of patients with RA.

METHODS

Nine RA patients with both an inflamed knee joint and an inflamed small joint (wrist or metacarpophalangeal joint) underwent an arthroscopic synovial biopsy of both joints on the same day. Multiple biopsy specimens were collected and stained for macrophages, T cells, plasma cells, fibroblast-like synoviocytes, and interleukin-6 (IL-6) by immunohistochemistry. Sections were evaluated by digital image analysis.

RESULTS

There were no significant differences in mean cell numbers for all markers investigated in samples from the knee joint compared with samples from the small joints. We detected statistically significant correlations for the numbers of sublining macrophages, T cells, and plasma cells, as well as for IL-6 expression, between the knee joint and the small joints. However, there was no significant correlation between different joints for the numbers of intimal macrophages or fibroblast-like synoviocytes.

CONCLUSION

The results of this study show that the inflammation in one inflamed joint is generally representative of that in other inflamed joints. Therefore, it is possible to use serial samples from the same joint, selecting either large or small joints, for the evaluation of antirheumatic therapies.

Immune features of seronegative and seropositive arthritis in early synovitis studies

Synovitis of recent onset is a challenging problem, both from a diagnostic and a mechanistic point of view. The role of the immune system in mediating the systemic and synovial inflammatory response remains an area of active investigation. Studies in early synovitis cohorts have confirmed the relatively specific association of rheumatoid factor positive polyarthritis with a number of autoantibodies, particularly anticyclical citrullinated peptide (CCP) antibodies, antifilaggarin antibodies (AFA), and anti-Sa antibodies. Immunopathologic studies of synovial tissue samples from patients with early synovitis have generally suggested quantitative rather than qualitative differences between various forms of synovitis. In particular, Th1 cytokines appear to predominate in rheumatoid arthritis and psoriatic synovitis, while Th2 cytokines are more often detectable in the synovium of reactive arthritis patients. This latter observation is consistent with an immune response profile that favors persistence of intracellular organisms.

Glucocorticoids in rheumatoid arthritis: effects on erosions and bone

Recently, four prospective placebo-controlled studies have further evaluated the disease-modifying properties of glucocorticoids in the treatment of rheumatoid arthritis. These studies irrefutably show that the use of (low) doses of glucocorticoids leads to a significant retardation of the progression of erosions, especially in early rheumatoid arthritis. This effect on erosions seems more impressive and probably more persistent than the well-known relief during low-dose glucocorticoid therapy of symptoms, such as pain, stiffness, and joint scores. The management of the (side) effects of glucocorticoids on bone has clearly improved in the last years. These two developments lead to a further optimizing of glucocorticoid treatment in patients with rheumatoid arthritis.