Matrix metalloproteinases-3, -8, -9 as markers of disease activity and joint damage progression in early rheumatoid arthritis

Endogenous MMP-9 and not MMP-2 promotes rheumatoid synovial fibroblast survival, inflammation and cartilage degradation

OBJECTIVE

The aim of this study was to investigate the effect of endogenous matrix metalloproteinases 2 and 9 (MMP-2 and MMP-9) on the invasive characteristics of RA synovial fibroblasts.

METHODS

Synovial fibroblasts isolated from patients with RA or OA were treated with MMP small interfering RNA (siRNA), inhibitors and recombinant proteins or TNF-α, with or without cartilage explants. Cell viability and proliferation were measured by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide and 5-bromo-2-deoxyuridine (BrdU) proliferation assays, respectively; apoptosis by an in situ cell death detection kit; migration and invasion by CytoSelect invasion assay, scratch migration and collagen gel assays; cartilage degradation by 1,9-dimethylmethylene blue assay; and inflammatory mediators and MMPs by ELISA, western blot and zymography.

RESULTS

MMP-2 was expressed by both OA and RA synovial fibroblasts, whereas only RA synovial fibroblasts expressed MMP-9. Suppressing MMP-2 or MMP-9 reduced RA synovial fibroblast proliferation equally. However, MMP-9 siRNA had greater effects compared with MMP-2 siRNA on promoting apoptosis and suppressing RA synovial fibroblast viability, migration and invasion. Suppression/inhibition of MMP-9 also decreased the production of IL-1β, IL-6, IL-8 and TNF-α, inactivated nuclear factor κB (NF-κB), extracellular signal-regulated kinase (ERK) and c-Jun NH2-terminal kinase (JNK) and suppressed RA synovial fibroblast-mediated cartilage degradation. In contrast, suppression/inhibition of MMP-2 stimulated TNF-α and IL-17 secretion and activated NF-κB, while recombinant MMP-2 (rMMP-2) inactivated NF-κB and suppressed RA synovial fibroblast-mediated cartilage degradation. Results using specific inhibitors and rMMPs provided supportive evidence for the siRNA results.

CONCLUSION

Endogenous MMP-2 or MMP-9 contribute to RA synovial fibroblast survival, proliferation, migration and invasion, with MMP-9 having more potent effects. Additionally, MMP-9 stimulates RA synovial fibroblast-mediated inflammation and degradation of cartilage, whereas MMP-2 inhibits these parameters. Overall, our data indicate that MMP-9 derived from RA synovial fibroblasts may directly contribute to joint destruction in RA.

A genetic variant in the region of MMP-9 is associated with serum levels and progression of joint damage in rheumatoid arthritis

OBJECTIVES

The severity of joint destruction is highly variable between rheumatoid arthritis (RA) patients. The majority of its heritability is still unexplained. Several autoimmune diseases share genetic risk variants that may also influence disease progression. We aimed to identify genetic risk factors for the severity of joint damage in RA by studying genetic susceptibility loci of several autoimmune diseases.

METHODS

In phase 1, 3143 sets of x-rays of 646 Dutch RA patients taken over 7 years (Sharp van der Heijde (SHS) scored) were studied. Genotyping was done by Immunochip. Associations of single-nucleotide polymorphisms (SNPs) with minor allele frequency (MAF) >0.01 and joint destruction were analysed. In phase 2, 686 North American RA patients with 926 SHS-scored x-rays over 15 years of follow-up were evaluated. In both phases multiple testing corrections were done for the number of uncorrelated SNPs; the thresholds for significance were p<1.1×10(-6) and p<0.0036. Matrix metalloproteinase 9 (MMP-9) levels were measured with ELISA in baseline serum samples.

RESULTS

In phase 1, 109 SNPs associated significantly with joint destruction (p<1.1×10(-6)). Of these, 76 were located in the HLA region; the 33 non-HLA variants were studied in phase 2. Here two variants were associated with the severity of joint destruction: rs451066 on chromosome 14 (p=0.002, MAF=0.20) and rs11908352 on chromosome 20 (p=0.002, MAF=0.21). Rs11908352 is located near the gene encoding MMP-9. Serum levels of MMP-9 were significantly associated with the rs11908352 genotypes (p=0.007).

CONCLUSIONS

These data indicate that two loci that confer risk to other autoimmune diseases also affect the severity of joint destruction in RA. Rs11908352 may influence joint destruction via MMP-9 production.

Knockdown of sphingosine kinase 1 inhibits the migration and invasion of human rheumatoid arthritis fibroblast-like synoviocytes by down-regulating the PI3K/AKT activation and MMP-2/9 production in vitro

To investigate the potential regulation of sphingosine kinase 1 (SPHK1) on the migration, invasion, and matrix metalloproteinase (MMP) expression in human rheumatoid arthritis fibroblast-like synoviocytes (RA-FLS). RA-FLS were transfected control siRNA or SPHK1 siRNA. The migration and invasion of unmanipulated control, control siRNA or SPHK1 siRNA- transfected RA-FLS in vitro were measured by the transwell system. The relative levels of SPHK1, PI3K, and AKT as well as AKT phosphorylation in RA-FLS were determined by Western blot. The levels of MMP-2/9 secreted by RA-FLS were detected by ELISA. Knockdown of SPHK1 significantly inhibited the spontaneous migration and invasion of RA-FLS, accompanied by significantly reduced levels of PI3K expression and AKT phosphorylation. Similarly, treatment with LY294002, an inhibitor of the PI3K/AKT pathway, inhibited the migration and invasion of RA-FLS. Knockdown of SPHK1 and treatment with the inhibitor synergistically inhibited the migration and invasion of RA-FLS, by further reducing the levels of PI3K expression and AKT phosphorylation. In addition, knockdown of SPHK1 or treatment with LY294002 inhibited the secretion of MMP-2 and MMP-9, and both synergistically reduced the production of MMP-2 and MMP-9 in RA-FLS in vitro. Knockdown of SPHK1 expression inhibits the PI3K/AKT activation, MMP-2 and MMP-9 expression, and human RA-FLS migration and invasion in vitro. Potentially, SPHK1 may be a novel therapeutic target for RA.

Matrix metalloproteinase-9: its interplay with angiogenic factors in inflammatory bowel diseases

Matrix metalloproteinase- (MMP-) 9 is one of the main metalloproteinases reported to be involved in extracellular matrix degradation and recently also in triggering of angiogenic switch in the course of inflammatory bowel diseases (IBD). The goal of our studies was to estimate in one experimental setting the levels of MMP-9 in sera of Crohn's Disease (CD) and ulcerative colitis (UC) patients and to evaluate its possible diagnostic potential in comparison with other biochemical markers and selected proinflammatory and angiogenic factors. The study group included 176 subjects (CD = 64, UC = 85, control = 27). Concentrations of serum MMP-9 were significantly higher in active than inactive forms of IBD, being higher in active UC than in active CD. Both in the case of CD and UC serum MMP-9 positively correlated with disease activity, IL-6 levels, platelet and leukocyte count, midkine, and PDGF-BB, as well as in UC with ESR and in CD with CRP, IL-1, and VEGF-A. Diagnostic accuracy of MMP-9 in distinguishing active UC from active CD was 66%, and displayed higher specificity than CRP (79.0% versus 61.6%, resp.). Evaluation of serum MMP-9 concentrations could aid in differentiation of active UC from active CD. MMP-9 correlated better with inflammatory and angiogenic parameters in CD than in UC.

Immune complexome analysis

Immune complexes (ICs) are produced during an immune response and may reflect some aspects of an ongoing immune response. Therefore, the identity of antigens incorporated into ICs provides the information that in the future may aid in the development of diagnosis and treatment strategies for autoimmune diseases, infection, cancer, and transplantation therapy, and this information might be more relevant than the information on free antigens. Because ICs may contain many antigens, comprehensive identification and profiling of such antigens are more effective than immunoblotting detection. Here, we introduced mass spectrometry (MS)-based two approaches (immunoproteomics and immune complexome analysis) to comprehensively identify the antigens. Immunoproteomics is a concept to identify disease-associated antigens that elicit immune responses by combining protein separation (two-dimensional electrophoresis, gel-free separation), immunological detection (Western blotting), and MS or by combining immunocapture and MS. Immune complexome analysis is designed for identifying antigens in circulating ICs and consists of ICs separation from serum and direct tryptic digestion followed by nano-liquid chromatography-tandem MS.

Leukocyte transmigration across endothelial and extracellular matrix protein barriers in liver ischemia/reperfusion injury

PURPOSE OF REVIEW

Hepatic ischemia reperfusion injury (IRI) linked to leukocyte recruitment and subsequent release of cytokines and free radicals remains a significant complication in organ transplantation. The aim of this review is to bring attention to advances made in our understanding of the mechanisms of leukocyte recruitment to sites of inflammatory stimulation in liver IRI.

RECENT FINDINGS

Leukocyte transmigration across endothelial and extracellular matrix barriers is dependent on adhesive events, as well as on focal matrix degradation mechanisms. Whereas adhesion molecules are critical for the successful promotion of leukocyte transmigration by providing leukocyte attachment to the vascular endothelium, matrix metalloproteinases (MMPs) are important for facilitating leukocyte movement across vascular barriers. Among different MMPs, MMP-9, an inducible gelatinase expressed by leukocytes during hepatic IRI, is emerging as an important mediator of leukocyte traffic to inflamed liver.

SUMMARY

It is generally accepted that the understanding of the molecular mechanisms involved in leukocyte recruitment will lead to the development of novel targeted therapeutic approaches for hepatic IRI and liver transplantation. Here, we review mechanisms of leukocyte traffic in liver IRI and the role of some of the proteins that are thought to be important for this process.

Detection of active matrix metalloproteinase-3 in serum and fibroblast-like synoviocytes of collagen-induced arthritis mice

The activity of rheumatoid arthritis (RA) correlates with the expression of proteases. Among several proteases, matrix metalloproteinase-3 (MMP-3) is one of the biological markers used to diagnose RA. The active form of MMP-3 is a key enzyme involved in RA-associated destruction of cartilage and bone. Thus, detection of active MMP-3 in serum or in vivo is very important for early diagnosis of RA. In this study, a soluble MMP-3 probe was prepared to monitor RA progression by detecting expression of active MMP-3 in collagen-induced arthritis (CIA) mice in vivo in both serum and fibroblast-like synoviocytes (FLSs). The MMP-3 probe exhibited strong sensitivity to MMP-3 and moderate sensitivity to MMP-7 at nanomolecular concentrations, but was not sensitive to other MMPs such as MMP-2, MMP-9, and MMP-13. In an optical imaging study, the MMP-3 probe produced early and strong NIR fluorescence signals prior to observation of erythema and swelling in CIA mice. The MMP-3 probe was able to rapidly and selectively detect and monitor active MMP-3 in diluted serum from CIA mice. Furthermore, histological data demonstrated that activated FLSs in arthritic knee joints expressed active MMP-3. Together, our results demonstrated that the MMP-3 probe may be useful for detecting active MMP-3 for diagnosis of RA. More importantly, the MMP-3 probe was able to detect active MMP-3 in diluted serum with high sensitivity. Therefore, the MMP-3 probe developed in this study may be a very promising probe, useful as a biomarker for early detection and diagnosis of RA.

Serum matrix metalloproteinase-3 in comparison with acute phase proteins as a marker of disease activity and radiographic damage in early rheumatoid arthritis

Matrix metalloproteinase-3 (MMP-3) is involved in the immunopathogenesis of rheumatoid arthritis (RA), but little is known about its relationship to genetic susceptibility and biomarkers of disease activity, especially acute phase reactants in early RA. MMP-3 was measured by ELISA in serum samples of 128 disease-modifying, drug-naïve patients and analysed in relation to shared epitope genotype, a range of circulating chemokines/cytokines, acute phase reactants, autoantibodies, cartilage oligomeric protein (COMP), and the simplified disease activity index (SDAI). MMP-3 was elevated >1.86 ng/ml in 56.25% of patients (P < 0.0001), correlated with several biomarkers, notably IL-8, IL-6, IFN γ , VEGF and COMP (r values = 0.22-0.33, P < 0.014-0.0001) and with CRP and SAA levels (r = 0.40 and 0.41, resp., P < 0.0000) and SDAI (r = 0.29, P < 0.0001), but not with erosions or nodulosis. However, the correlations of CRP and SAA with SDAI were stronger (respective values of 0.63 and 0.54, P < 0.001 for both). COMP correlated with smoking, RF, and MMP-3. MMP-3 is significantly associated with disease activity, inflammatory mediators and cartilage breakdown, making it a potential biomarker of disease severity, but seemingly less useful than CRP and SAA as a biomarker of disease activity in early RA.

Matrix metalloproteinase (MMP)-9: a proximal biomarker for cardiac remodeling and a distal biomarker for inflammation

Adverse cardiac remodeling following myocardial infarction (MI) remains a significant cause of congestive heart failure. Additional and novel strategies that improve our ability to predict, diagnose, or treat remodeling are needed. Numerous groups have explored single and multiple biomarker strategies to identify diagnostic prognosticators of remodeling progression, which will improve our ability to promptly and accurately identify high-risk individuals. The identification of better clinical indicators should further lead to more effective prediction and timely treatment. Matrix metalloproteinase (MMP-9) is one potential biomarker for cardiac remodeling, as demonstrated by both animal models and clinical studies. In animal MI models, MMP-9 expression significantly increases and is linked with inflammation, diabetic microvascular complications, extracellular matrix degradation and synthesis, and cardiac dysfunction. Clinical studies have also established a relationship between MMP-9 and post-MI remodeling and mortality, making MMP-9 a viable candidate to add to the multiple biomarker list. By definition, a proximal biomarker shows a close relationship with its target disease, whereas a distal biomarker exhibits non-targeted disease modifying outcomes. In this review, we explore the ability of MMP-9 to serve as a proximal biomarker for cardiac remodeling and a distal biomarker for inflammation. We summarize the current molecular basis and clinical platform that allow us to include MMP-9 as a biomarker in both categories.

NKG2D stimulated T-cell autoreactivity in giant cell arteritis and polymyalgia rheumatica

OBJECTIVE

To investigate functional expression of NKG2D on CD4 and CD8 T-cells in patients with giant cell arteritis (GCA) and polymyalgia rheumatica (PMR).

METHODS

Peripheral blood was drawn from patients with GCA (n=16), PMR (n=78) and healthy controls (HC, n=64). Tissue samples were obtained from GCA patients and controls. Proliferation and cytokine production assays were performed using CFSE and intracellular IFN-γ or TNF-α staining, respectively, and flow cytometry analysis. Immunofluorescence and immunohistology were applied to analyse the presence of NKG2D-expressing T-cells and NKG2D-ligands in temporal arteries, respectively. mRNA levels of NKG2D-ligands were determined by RT-PCR.

RESULTS

In both GCA and PMR patients, NKG2D was preferentially expressed on senescent CD4CD28(-) and CD8CD28(-), as well as on CD8CD28 T-cells. Frequencies of senescent T-cells were increased in GCA and PMR patients compared to HC. In GCA tissue samples, infiltrating T-cells were predominately CD28(-). NKG2D expressing T-cells concentrated around the vasa vasorum of the adventitia. Antigenic stimulation induced rapid up-regulation of NKG2D on CD4CD28(-) and CD4CD28 T-cells, whereas TNF-α and interleukin-15 enhanced NKG2D expression on senescent CD4 and CD8 T-cells only. NKG2D cross-linkage augmented anti-CD3 triggered proliferation, IFN-γ and TNF-α production of CD8 T-cells. In CD4CD28(-) T-cells, NKG2D ligation resulted in increased IFN-γ production only. NKG2D ligands were expressed in temporal arteries from GCA patients, particularly in the adventitial and medial layers of affected vessels.

CONCLUSIONS

NKG2D is functionally expressed on CD4CD28(-) and CD8 T-cells in GCA and PMR. NKG2D-ligands are present in temporal arteries and may co-stimulate NKG2D expressing T-cells.

Validation of a novel multibiomarker test to assess rheumatoid arthritis disease activity

Objective Quantitative assessment of disease activity in rheumatoid arthritis (RA) is important for patient management, and additional objective information may aid rheumatologists in clinical decision making. We validated a recently developed multibiomarker disease activity (MBDA) test relative to clinical disease activity in diverse RA cohorts.

Methods Serum samples were obtained from the Index for Rheumatoid Arthritis Measurement, Brigham and Women's Hospital Rheumatoid Arthritis Sequential Study, and Leiden Early Arthritis Clinic cohorts. Levels of 12 biomarkers were measured and combined according to a prespecified algorithm to generate the composite MBDA score. The relationship of the MBDA score to clinical disease activity was characterized separately in seropositive and seronegative patients using Pearson's correlations and the area under the receiver operating characteristic curve (AUROC) to discriminate between patients with low and moderate/high disease activity. Associations between changes in MBDA score and clinical responses 6–12 weeks after initiation of anti–tumor necrosis factor or methotrexate treatment were evaluated by the AUROC.

Results The MBDA score was significantly associated with the Disease Activity Score in 28 joints using the C-reactive protein level (DAS28-CRP) in both seropositive (AUROC 0.77, P < 0.001) and seronegative (AUROC 0.70, P < 0.001) patients. In subgroups based on age, sex, body mass index, and treatment, the MBDA score was associated with the DAS28-CRP (P < 0.05) in all seropositive and most seronegative subgroups. Changes in the MBDA score at 6–12 weeks could discriminate both American College of Rheumatology criteria for 50% improvement responses (P = 0.03) and DAS28-CRP improvement (P = 0.002). Changes in the MBDA score at 2 weeks were also associated with subsequent DAS28-CRP response (P = 0.02).

Conclusion Our findings establish the criterion and discriminant validity of a novel multibiomarker test as an objective measure of RA disease activity to aid in the management of RA in patients with this condition.

Enhanced expression and fucosylation of ficolin3 in plasma of RA patients

OBJECTIVES

The aim of this work was to detect low abundant proteins, which may be potential biomarkers of rheumatoid arthritis (RA) at the early stage. We compared plasma protein profiles of RA patients with healthy individuals in two dimensional gel electrophoresis after removal of abundant proteins (albumin and IgG) using depletion kit and Aleuria aurantia lectin (AAL) affinity chromatography.

DESIGN AND METHODS

Forty plasma samples each from healthy control individuals and RA patients were used in this study.

RESULTS

We found ficolin 3, haptoglobin alpha chain, IgM chain, alpha-1-antitrypsin and hemopexin precursor to be up regulated in the plasma of RA patients. These proteins were identified by matrix assisted laser desorption ionization-time of flight (MALDI-TOF) from several reproducible 2D gels. Ficolin 3, which was not at all visible in albumin and IgG depleted gels, but detected in AAL bound fractions, was further verified by immunobloting and enzyme immunoassay. Elevated fucosylation in ficolin 3 was detected using high performance anion exchange chromatography-pulse amperometric detection (HPAEC-PAD), lectin blotting and enzyme linked lectin binding assay.

CONCLUSIONS

Altered fucosylation and elevated level of Ficolin 3 might be exploited to be a potential marker for diagnosis of RA.

Performance of a multi-biomarker score measuring rheumatoid arthritis disease activity in the CAMERA tight control study

OBJECTIVES

To evaluate the performance of individual biomarkers and a multi-biomarker disease activity (MBDA) score in the early rheumatoid arthritis (RA) patient population from the computer assisted management in early rheumatoid arthritis (CAMERA) study.

METHODS

Twenty biomarkers were measured in the CAMERA cohort, in which patients were treated with either intensive or conventional methotrexate-based treatment strategies. The MBDA score was calculated using the concentrations of 12 biomarkers (SAA, IL-6, TNF-RI, VEGF-A, MMP-1, YKL-40, MMP-3, EGF, VCAM-1, leptin, resistin and CRP) according to a previously trained algorithm. The performance of the scores was evaluated relative to clinical disease activity assessments. Change in MBDA score over time was assessed by paired Wilcoxon rank sum test. Logistic regression was used to evaluate the ability of disease activity measures to predict radiographic progression.

RESULTS

The MBDA score had a significant correlation with the disease activity score based on 28 joints-C reactive protein (DAS28-CRP) (r=0.72; p<0.001) and an area under the receiver operating characteristic curve for distinguishing remission/low from moderate/high disease activity of 0.86 (p<0.001) using a DAS28-CRP cut-off of 2.7. In multivariate analysis the MBDA score, but not CRP, was an independent predictor of disease activity measures. Additionally, mean (SD) MBDA score decreased from 53 (18) at baseline to 39 (16) at 6 months in response to study therapy (p<0.0001). Neither MBDA score nor clinical variables were predictive of radiographic progression.

CONCLUSIONS

This multi-biomarker test performed well in the assessment of disease activity in RA patients in the CAMERA study. Upon further validation, this test could be used to complement currently available disease activity measures and improve patient care and outcomes.

Synovium CD20 expression is a potential new predictor of bone erosion progression in very-early arthritis treated by sequential DMARDs monotherapy -- a pilot study from the VErA cohort

OBJECTIVE

Because available biomarkers (rheumatoid factors [RF], anti-cyclic citrullinated autoantibodies [anti-CCP2], erythrocyte sedimentation rate at 1st hour [ESR]/C-reactive peptide [CRP] and bone erosions) are insufficient to predict rheumatoid arthritis (RA) structural damage, to determine whether synovium expression of greater or equal to 1 markers could constitute new prognostic factor(s).

METHOD

The study was conducted on 18 prospectively enrolled disease-modifying anti-rheumatic drug (DMARD)- and glucocorticoid-naïve, VErA cohort patients with very-early arthritis (median duration: 4months). Recorded at baseline were: clinical and biological (serum ESR, CRP, RF-isotypes, anti-CCP2, osteoprotegerin, receptor activator of nuclear κB-ligand [RANK-L] and cartilage oligomeric matrix protein [COMP] levels) data; synovium expression (HLA-DR, CD163, CD3, CD20, VEGF, osteoprotegerin, RANK-L, Bcl2 and global inflammation index) for a metacarpophalangeal joint-synovium biopsy. Baseline and 3-year hand-and-foot X-rays were graded with the van der Heijde-modified-Sharp score; the judgment criterion was its progression during follow-up. Pearson's product moment correlation statistics were used to test for association between paired samples.

RESULTS

A baseline, a significant relationship was found between erosive damage and markers of B-cell activation, notably the synovium CD20 expression (r=0.68; P=0.0001). Quantified by the modified-Sharp erosion score variation, the 3-year structural damage progression was significantly correlated with: serum levels of RF-IgG (r=0.75; P=0.0003), -IgM (r=0.69; P=0.001), anti-CCP2 (r=0.53; P=0.02) and RANK-L (r=0.61; P=0.007); synovium CD20 expression (r=0.70; P=0.001).

CONCLUSION

This analysis of the prognostic value of a large panel of synovium markers in a limited sample of prospectively followed, well-documented patients suggested that both synovial CD20 and serum RANK-L levels might be new predictors of structural damage progression in very-early RA.

Early diagnosis of arthritis in mice with collagen-induced arthritis, using a fluorogenic matrix metalloproteinase 3-specific polymeric probe

OBJECTIVE

Early treatment based on an early diagnosis of rheumatoid arthritis (RA) could halt progression of the disease, but early diagnosis is often difficult. Matrix metalloproteinase 3 (MMP-3) is thought to be particularly important in the pathogenesis of RA. The aim of this study was to investigate whether an MMP-3-specific polymeric probe could be used for early diagnosis and for visualizing the progression of arthritis, using a near-infrared fluorescence (NIRF) imaging system.

METHODS

The MMP-3-specific polymeric probe was developed by conjugating NIRF dye, MMP substrate peptide, and dark quencher to self-assembled chitosan nanoparticles. One hour after intravenous administration of the probe, fluorescent images of mice with collagen-induced arthritis at different stages of disease development were obtained. The correlation between the fluorescence recovered in in vivo imaging when using an MMP-3-specific polymeric probe and up-regulated MMP-3 activity in the joint tissues was evaluated by Western blotting and immunohistochemical staining. Histologic analysis and micro-computed tomography (micro-CT) were also used to assess arthritis progression.

RESULTS

A significantly higher NIRF signal was recovered from arthritic joints compared with normal joints at 14 days after the first immunization, before any erythema or swelling could be observed with the naked eye or any erosion was detected by histologic analysis or micro-CT. The results of immunohistochemical analysis and Western blotting confirmed that the fluorescence recovered in the in vivo imaging was related to up-regulated MMP-3 activity in the joint tissues.

CONCLUSION

An MMP-3-specific polymeric probe provided clear early diagnosis of arthritis and visualization of arthritis progression using an NIRF imaging system. This approach could be used for early diagnosis and for monitoring drug and surgical therapies in individual cases.

Correlation of MMP-3 and MMP-9 with Crohn's disease activity in children

BACKGROUND

Recently published data indicate that the inflammation in Crohn's disease (CD) may be accompanied by elevated levels of matrix metalloproteinases.

AIMS

The goals of the present study were the estimation of MMP-3 and -9 concentrations in sera of children with Crohn's disease, the examination of correlation between the concentrations of MMP-3 and -9 and clinical activity of the disease in the relation to the control group and the evaluation of the utility of MMP-3 and -9 concentration measurements as markers of disease activity.

METHODS

Serum concentrations of MMP-3 and -9 were estimated in 82 children (45 CD patients divided into severe, moderate and mild subgroups; 37 controls) and correlated with disease activity estimated by the Pediatric Crohn's Disease Activity Index (PCDAI), CRP, seromucoid and ESR.

RESULTS

Mean MMP-3 concentrations were: 2.49 ng/ml (95% CI: 1.76-3.52) for mild, 16.44 ng/ml (95% CI: 10.34-26.15) for moderate, 5.25 ng/ml (95% CI: 2.73-10.11) for severe CD and 1.95 ng/ml (95% CI: 1.53-2.48) for the control group (differences between all three groups were statistically significant; P < 0.001). Median MMP-9 concentrations were: 2.14 ng/ml (95% CI: 0-8.9) for mild, 14.21 ng/ml (95% CI: 4.53-21.48) for moderate, 42.2 ng/ml (95% CI: 5.74-61.27) for severe CD and 1.3 ng/ml (95% CI: 0.7-2.18) for the control group. MMP-9 concentrations in moderate and severe CD differed from the concentrations in mild CD (P = 0.002) and control group (P = 0.0001). MMP-3 concentration significantly correlated with MMP-9, PCDAI and ESR, while MMP-9 concentration significantly positively correlated with MMP-3, PCDAI, and CRP. Diagnostic utilities of the tests were: MMP-3 accuracy 75%, positive likelihood ratio (LR+) = 4.11 and negative likelihood ratio (LR-) = 0.51, sensitivity 56%, specificity 87%, Youden index 0.43; for MMP-9, accuracy 73%, LR+ = 5.14 and LR- = 0.50, sensitivity 56%, specificity 89%, Youden index 0.45; and for CRP, accuracy 74%, LR+ = 8.56 and LR- = 0.54, sensitivity 49%, specificity 94%, Youden index 0.43.

CONCLUSIONS

MMP-9 serum concentration increasing along with the activity of the disease, exhibiting high specificity and correlating well with the indices of inflammation might be of better usefulness in the prediction of CD activity status in children than MMP-3.

Baseline serum MMP-3 levels in patients with Rheumatoid Arthritis are still independently predictive of radiographic progression in a longitudinal observational cohort at 8 years follow up

Introduction

At present, there is no reliable tool for predicting disease outcome in patients with rheumatoid arthritis (RA). We previously demonstrated an association between specific baseline biomarkers/clinical measures including matrix metalloproteinase-3 (MMP-3) and 2-year radiographic progression in patients with RA. This study further evaluates the predictive capability of these baseline variables with outcome extended over 8-years.

Methods

Fifty-eight of the original cohort (n = 118) had radiographic progression from baseline to mean 8.2-years determined using the van der Heijde modified Sharp method. The contribution of each predictor variable towards radiographic progression was assessed with univariate and multivariate analyses.

Results

Traditional factors (including erythrocyte sedimentation rate, C-reactive protein, anti-cyclic citrullinated peptide (anti-CCP), and rheumatoid factor) and biomarkers of tissue destruction (including MMP-3, C-telopeptide of type II collagen, cartilage oligomeric matrix protein, and tissue inhibitor of metalloproteinase 1) measured at baseline were associated with radiographic progression at endpoint. Multivariate logistic regression identified anti-CCP seropositivity [OR 9.29, 95%CI: 2.29-37.64], baseline elevated MMP-3 [OR 8.25, 95%CI: 2.54-26.78] and baseline radiographic damage [OR 5.83, 95%CI: 1.88-18.10] as the strongest independent predictors of radiographic progression. A model incorporating these variables had a predictive accuracy of 0.87, assessed using the area under the receiver operating characteristic curve.

Conclusion

In our cohort with onset of RA symptoms < 2-years, multivariate analysis identified anti-CCP status and baseline MMP-3 as the strongest independent predictors of radiographic disease outcome at 8.2-years. This finding suggests determination of baseline MMP-3, in conjunction with traditional serologic markers, may provide additional prognostic information for patients with RA. Furthermore, these findings highlight the importance of continued research into a broad range of biomarkers as potential predictors of joint damage.

Human matrix metalloproteinases: an ubiquitarian class of enzymes involved in several pathological processes

Human matrix metalloproteinases (MMPs) belong to the M10 family of the MA clan of endopeptidases. They are ubiquitarian enzymes, structurally characterized by an active site where a Zn(2+) atom, coordinated by three histidines, plays the catalytic role, assisted by a glutamic acid as a general base. Various MMPs display different domain composition, which is very important for macromolecular substrates recognition. Substrate specificity is very different among MMPs, being often associated to their cellular compartmentalization and/or cellular type where they are expressed. An extensive review of the different MMPs structural and functional features is integrated with their pathological role in several types of diseases, spanning from cancer to cardiovascular diseases and to neurodegeneration. It emerges a very complex and crucial role played by these enzymes in many physiological and pathological processes.

Matrix metalloproteinase-9 inhibition reduces inflammation and improves motility in murine models of postoperative ileus

BACKGROUND & AIMS

Matrix metalloproteinase (MMP)-9, a member of the gelatinase family of MMPs, mediates leukocyte migration during inflammation. Inflammation contributes to development of postoperative ileus (POI), which is caused by physical disturbances to the bowel during abdominal surgery. We evaluated the role of MMP-9 in POI and investigated whether disruption of MMP-9 or administration of an inhibitor of MMP-9 activity reduced cellular inflammation and bowel dysmotility in rat and mouse models of POI.

METHODS

Mice and rats underwent laparotomy and bowel manipulation; bowel tissues were collected 3 to 24 hours later and analyzed by real-time reverse-transcriptase polymerase chain reaction, immunoblot, in situ zymography, and functional analyses.

RESULTS

Bowel manipulation resulted in a time-dependent increase in MMP-9 expression within the intestinal muscularis; increases in MMP-9 messenger RNA were inducible nitric oxide synthase dependent. Immunoblot analyses confirmed the presence of the proenzyme and the catalytically active form of MMP-9. Administration of MMP-2/MMP-9 II, a dual active-site inhibitor, reduced the number of myeloperoxidase-positive immune cells that infiltrated the muscularis and prevented the surgically induced reduction in bowel smooth muscle contractility. Zymography analysis, performed in muscularis whole mounts in situ, indicated that MMP-9 and not MMP-2 mediated the gelatinase activity observed in infiltrating cells. MMP-9 knockout mice were protected from the inflammation and dysmotility associated with POI.

CONCLUSIONS

MMP-9 mediates cellular inflammatory responses within the intestinal muscularis in mouse and rat models of POI. Inhibition of MMP-9 activity reduced recruitment of immune cells to the intestinal muscularis, preventing loss of smooth muscle contractility. Induction of MMP-9 expression requires inducible nitric oxide synthase.

The Effect of Synovial Fluid Enzymes on the Biodegradability of Collagen and Fibrin Clots

Recently there has been a great deal of interest in the use of biomaterials to stimulate wound healing. This is largely due to their ability to centralize high concentrations of compounds known to promote wound healing at a needed location. Joints present a unique challenge to using scaffolds because of the presence of enzymes in synovial fluid which are known to degrade materials that would be stable in other parts of the body. The hypothesis of this study was that atelocollagen scaffolds would have greater resistance to enzymatic degradation than scaffolds made of gelatin, fibrin and whole blood. To test this hypothesis, collagen and fibrin-based scaffolds were placed in matrix metallopeptidase-1 (MMP-1), elastase, and plasmin solutions at physiologic concentrations, and the degradation of each scaffold was measured at varying time points. The atelocollagen scaffolds had a significantly greater resistance to degradation by MMP-1, elastase and plasmin over the fibrin based scaffolds. The results suggest that atelocollagen-based scaffolds may provide some protection against premature degradation by synovial fluid enzymes over fibrin-based matrices.

Inhibiting effects of Leflunomide metabolite on overexpression of CD147, MMP-2 and MMP-9 in PMA differentiated THP-1 cells

Recent studies have reported elevated expression of cluster of differentiation (CD) 147 on CD14(+) monocytes of the peripheral blood of patients with active rheumatoid arthritis and a correlation of CD147 expression with Disease Activity Score. Thus, CD147 may be a new target for treatment of rheumatoid arthritis. Leflunomide is a disease-modifying antirheumatic drug that is commonly used to treat rheumatoid arthritis. The effect of leflunomide in blocking the up-regulation of CD147 and in blocking the down-regulation of metalloproteinases (MMP)-2 and MMP-9 in active macrophages has not yet been established. In this study we investigated the effect of A771726, the active metabolite of leflunomide, on expression of CD147 and on the gelatinolytic activity of MMP-2 and MMP-9 in phorbol myristate acetate (PMA) differentiated THP-1 cells. The expression of CD147, MMP-2, and MMP-9 mRNAs were determined by real-time quantitative reverse transcription PCR, the levels of cellular surface expression of CD147 were determined by flow cytometry, and the gelatinolytic activity of MMP-2 and MMP-9 were determined by zymography. Our results showed that A771726 significantly inhibited the expression of CD147 on the cell surface of activated THP-1 cells in a dose-dependent manner (P<0.01), inhibited the expression of MMP-2 and MMP-9 mRNAs in a dose-dependent manner (P<0.01), and inhibited the gelatinolytic activity of MMP-2 and MMP-9 at concentration of 15 μg/ml and 45 μg/ml (P<0.01). Our results indicate that A771726, the active metabolite of leflunomide, inhibited CD147 expression at the protein level and inhibited gelatinolytic activity of MMP-2 and MMP-9 in PMA-differentiated THP-1 cells.

Matrix metalloproteinase-8 deficiency increases joint inflammation and bone erosion in the K/BxN serum-transfer arthritis model

Introduction

Rheumatoid arthritis is an autoimmune disease in which joint inflammation leads to progressive cartilage and bone erosion. Matrix metalloproteinases (MMPs) implicated in homeostasis of the extracellular matrix play a central role in cartilage degradation. However, the role of specific MMPs in arthritis pathogenesis is largely unknown. The aim of the present study was to investigate the role of Mmp-8 (collagenase-2) in an arthritis model.

Methods

Arthritis was induced in Mmp8-deficient and wildtype mice by K/BxN serum transfer. Arthritis severity was measured by a clinical index and ankle sections were scored for synovial inflammation, cartilage damage and bone erosion. cDNA microarray analysis, real-time PCR and western blot were performed to identify differential changes in gene expression between mice lacking Mmp8 and controls.

Results

Mmp8 deficiency increased the severity of arthritis, although the incidence of disease was similar in control and deficient mice. Increased clinical score was associated with exacerbated synovial inflammation and bone erosion. We also found that the absence of Mmp8 led to increased expression of IL-1β, pentraxin-3 (PTX3) and prokineticin receptor 2 (PROKR2) in arthritic mice joints.

Conclusions

Lack of Mmp-8 is accompanied by exacerbated synovial inflammation and bone erosion in the K/BxN serum-transfer arthritis model, indicating that this Mmp has a protective role in arthritis.

Angiopoietin-2 is highly correlated with inflammation and disease activity in recent-onset rheumatoid arthritis and could be predictive for cardiovascular disease

OBJECTIVE

To investigate whether serum levels of endothelial cell activation markers in early RA patients can serve as biomarkers for inflammation and disease activity, and are associated with radiological progression and development of cardiovascular disease (CVD).

METHODS

Serum levels of VEGF, soluble vascular cell adhesion molecule (sVCAM)-1 and angiopoietin-2 (Angpt-2) were measured by ELISA in 176 patients with recent-onset RA, at the time of diagnosis and after 2 years. Markers of inflammation and disease activity were assessed, as well as radiological damage of hands and feet, at diagnosis and after 2 years. Prevalence of CVD of all patients after 12.5 years disease duration was retrieved from medical records.

RESULTS

Patients with RA had higher levels of VEGF and Angpt-2 at disease onset compared with healthy controls, which correlated with markers of inflammation, but were not predictive of radiological progression after 2 years. Angpt-2 levels, moreover, significantly correlated with measures of disease activity. Nearly 18% of RA patients developed CVD after an average of 12.5 years of disease, and these patients had a significantly higher level of Angpt-2 at the onset of RA compared with patients who did not develop CVD.

CONCLUSIONS

In early RA, markers of endothelial activation are highly correlated with inflammation and disease activity, but not with radiological progression. Angpt-2 could be predictive for the development of CVD since Angpt-2 levels were significantly higher in CVD patients than in non-CVD patients.

Anti-apolipoprotein A-1 IgG predicts major cardiovascular events in patients with rheumatoid arthritis

OBJECTIVE

To determine whether anti-apolipoprotein A-1 (anti-Apo A-1) IgG are associated with major cardiovascular events in patients with rheumatoid arthritis (RA).

METHODS

We determined anti-Apo A-1 IgG levels and the concentrations of cytokines, oxidized low-density lipoprotein (LDL), and matrix metalloproteinase 1 (MMP-1) MMP-2, MMP-3, and MMP-9 in sera from 133 patients with RA who did not have cardiovascular disease at baseline, all of whom were longitudinally followed up over a median period of 9 years. A major cardiovascular event was defined as a fatal or nonfatal stroke or acute coronary syndrome. The proinflammatory effects of anti-Apo A-1 IgG were assessed on human macrophages in vitro.

RESULTS

During followup, the overall incidence of major cardiovascular events was 15% (20 of 133 patients). At baseline, anti-Apo A-1 IgG positivity was 17% and was associated with a higher incidence of major cardiovascular events (adjusted hazard ratio 4.2, 95% confidence interval 1.5-12.1). Patients who experienced a subsequent major cardiovascular event had higher circulating levels of anti-Apo A-1 IgG at baseline compared with those who did not have a major cardiovascular event. Receiver operating curve analysis showed that anti-Apo A-1 IgG was the strongest of all tested biomarkers for the prediction of a subsequent major cardiovascular event, with an area under the curve value of 0.73 (P = 0.0008). At the predefined and previously validated cutoff levels, the specificity and sensitivity of anti-Apo A-1 IgG to predict major cardiovascular events were 50% and 90%, respectively. Anti-Apo A-1 IgG positivity was associated with higher median circulating levels of interleukin-8 (IL-8), oxidized LDL, and MMP-9 and higher proMMP-9 activity as assessed by zymography. On human macrophages, anti-Apo A-1 IgG induced a significant dose-dependent increase in IL-8 and MMP-9 levels and proMMP-9 activity.

CONCLUSION

Anti-Apo A-1 IgG is an independent predictor of major cardiovascular events in RA, possibly by affecting vulnerability to atherosclerotic plaque.

Soluble biomarkers of cartilage and bone metabolism in early proof of concept trials in psoriatic arthritis: effects of adalimumab versus placebo

BACKGROUND

There is growing interest in soluble biomarkers that could be used on the group level for screening purposes in small proof of principle studies during early drug development. We investigated early changes in serum levels of several candidate biomarkers involved in cartilage and bone metabolism following the initiation of adalimumab as a prototypic active treatment in psoriatic arthritis (PsA) compared to placebo.

MATERIALS AND METHODS

Twenty-four PsA patients were randomized to receive either adalimumab 40 mg s.c. every other week or placebo for 4 weeks, followed by an open label extension phase. Serum samples were obtained at baseline and after 4 and 12 weeks of treatment and analyzed for levels of CPII and PINP (synthesis of type II and type I procollagen), melanoma inhibitory activity (MIA) (chondrocyte anabolism), matrix metalloproteinase (MMP)-3, C2C and cartilage oligomeric matrix protein (COMP) (type II collagen degradation), osteocalcin (OC) (bone formation), NTX-I and ICTP (both type I collagen degradation).

RESULTS

After 4 weeks, there was a significant decrease in serum MMP-3 levels in adalimumab-treated patients (P<0.005), while no change was observed in the placebo group. A significant increase in serum MIA was noted after adalimumab therapy (P<0.005) but not after placebo treatment. After 12 weeks, there was a marked reduction in serum MMP-3 in both groups (P<0.005), whereas other markers did not show significant changes compared to baseline.

CONCLUSION

MMP-3 and MIA could serve as soluble biomarkers associated with inflammation as well as joint remodelling and destruction and may, together with clinical evaluation and in combination with other biomarkers, assist in distinguishing between effective and ineffective therapy in small, proof-of-principle studies of short duration in PsA.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN23328456.

The role of biomarkers in the management of patients with rheumatoid arthritis

In recent years, patient outcomes have improved dramatically with the availability of effective treatments for the management of rheumatoid arthritis (RA). RA, however, is a heterogeneous disease with variable disease progression and treatment response. Whereas some patients respond to a single disease-modifying antirheumatic drug, others require more intensive treatment strategies. Assessing disease severity at diagnosis and monitoring disease activity on an individual level would be a more accurate way of tailoring therapy, ensuring optimal treatment for those at greatest risk of disease progression, long-term disability, and joint damage without unnecessary overtreatment. Assessment of disease activity and severity is currently based on a combination of clinical and laboratory parameters that aid treatment decisions. Use of biomarkers may provide a more accurate means of objectively assessing the disease. This article reviews the role of biomarkers in the management of RA.

Contribution of cyclophilin A to the regulation of inflammatory processes in rheumatoid arthritis

INTRODUCTION

Previous studies show that cyclophilin A (CypA) acts as a strong chemotactic cytokine to neutrophils, eosinophils, and monocytes in rheumatoid arthritis (RA).

METHODS

In this study, monocytes were stimulated by purified CypA and the production of matrix metalloproteinase (MMPs), the cell invasion and the release of inflammatory cytokines were detected respectively by gelatin zymography, invasion assay, and cytometric bead array FCM.

RESULTS

The elevated level of inflammatory cytokine IL-8 was also detected. Results showed that CypA significantly promoted the invasion of THP-1 cells and increased the production of MMP-2 and MMP-9, which displayed a biphasic concentration dependency. In vivo experiments found that the cartilage erosion scores in CypA injection group were significantly higher than those in control group (P < 0.05).

CONCLUSION

Our findings suggest that CypA significantly enhances the secretion of MMP-2 and MMP-9, the cell invasion, and the inflammatory cytokines production of monocytes. Our findings may shed some new light on the inflammatory process and the degradation of cartilage and bone in RA.

Testing of the OMERACT 8 Draft Validation Criteria for a Soluble Biomarker Reflecting Structural Damage in Rheumatoid Arthritis: A Systematic Literature Search on 5 Candidate Biomarkers

Objective.

To test the OMERACT 8 draft validation criteria for soluble biomarkers by assessing the strength of literature evidence in support of 5 candidate biomarkers.

Methods.

A systematic literature search was conducted on the 5 soluble biomarkers RANKL, osteoprotegerin (OPG), matrix metalloprotease (MMP-3), urine C-telopeptide of types I and II collagen (U-CTX-I and U CTX-II), focusing on the 14 OMERACT 8 criteria. Two electronic voting exercises were conducted to address: (1) strength of evidence for each biomarker as reflecting structural damage according to each individual criterion and the importance of each individual criterion; (2) overall strength of evidence in support of each of the 5 candidate biomarkers as reflecting structural damage endpoints in rheumatoid arthritis (RA) and identification of omissions to the criteria set.

Results.

The search identified 111 articles. The strength of evidence in support of these biomarkers reflecting structural damage was low for all biomarkers and was rated highest for U-CTX-II [score of 6.5 (numerical rating scale 0–10)]. The lowest scores for retention of specific criteria in the draft set went to criteria that refer to the importance of animal studies, correlations with other biomarkers reflecting damage, and an understanding of the metabolism of the biomarker.

Conclusion.

Evidence in support of any of the 5 tested biomarkers (MMP-3, CTX-I, CTX-II, OPG, RANKL) was inadequate to allow their substitution for radiographic endpoints in RA. Three of the criteria in the draft criteria set might not be required, but few omissions were identified.

Inducible nitric oxide synthase deficiency impairs matrix metalloproteinase-9 activity and disrupts leukocyte migration in hepatic ischemia/reperfusion injury

Matrix metalloproteinase 9 (MMP-9) is a critical mediator of leukocyte migration in hepatic ischemia/reperfusion (I/R) injury. To test the relevance of inducible nitric oxide synthase (iNOS) expression on the regulation of MMP-9 activity in liver I/R injury, our experiments included both iNOS-deficient mice and mice treated with ONO-1714, a specific iNOS inhibitor. The inability of iNOS-deficient mice to generate iNOS-derived nitric oxide (NO) profoundly inhibited MMP-9 activity and depressed leukocyte migration in livers after I/R injury. While macrophages expressed both iNOS and MMP-9 in damaged wild-type livers, neutrophils expressed MMP-9 and were virtually negative for iNOS; however, exposure of isolated murine neutrophils and macrophages to exogenous NO increased MMP-9 activity in both cell types, suggesting that NO may activate MMP-9 in leukocytes by either autocrine or paracrine mechanisms. Furthermore, macrophage NO production through the induction of iNOS was capable of promoting neutrophil transmigration across fibronectin in a MMP-9-dependent manner. iNOS expression in liver I/R injury was also linked to liver apoptosis, which was reduced in the absence of MMP-9. These results suggest that MMP-9 activity induced by iNOS-derived NO may also lead to detachment of hepatocytes from the extracellular matrix and cell death, in addition to regulating leukocyte migration across extracellular matrix barriers. These data provide evidence for a novel mechanism by which MMP-9 can mediate iNOS-induced liver I/R injury.

Plasma levels of matrix metalloproteinase-9 are independently associated with psychosocial factors in a middle-aged normal population

OBJECTIVE

To test the association between psychosocial factors and circulating levels of matrix metalloproteinase-9 (MMP-9) in a normal population sample. Psychosocial factors have been associated with inflammatory markers and are of prognostic significance for coronary artery disease (CAD). The degrading enzyme MMP-9 is upregulated in inflammatory processes and hypothesized to play a role in the rupture of atherosclerotic plaques.

METHODS

A total of 402 participants (50% women), aged 45 to 69 years, were drawn randomly from a normal population. Psychosocial instruments covered depression (Center for Epidemiological Studies Depression Questionnaire, CES-D), vital exhaustion, hostile affect, cynicism, mastery, self-esteem, sense of coherence (SOC), emotional support, and social integration. Plasma MMP-9 was measured by an enzyme-linked immunosorbent assay method. Linear regression models were adjusted for age, sex, known CAD, rheumatoid arthritis, cancer, cardiovascular risk factors including C-reactive protein and ongoing medication.

RESULTS

After full adjustment, there were independent associations of elevated MMP-9 levels with CES-D (+2.9 ng/ml per SD, p = .02), hostile affect (+3.0 ng/ml per SD, p = .02), cynicism (+3.5 ng/ml per SD, p = .006), and SOC (-2.5 ng/ml per SD, p = .046). A principal component analysis extracted three components. The first was mainly extracted from CES-D, vital exhaustion, self-esteem, mastery, and SOC; the second was mainly extracted from hostile affect and cynicism. Both were independently associated with MMP-9 (p = .02, p = .04) when run in the same model.

CONCLUSIONS

MMP-9 levels were associated with psychosocial factors in a middle-aged normal population sample, independently of traditional risk factors. The findings may constitute a possible link between psychosocial factors and cardiovascular risk.

Common inflammatory mediators orchestrate pathophysiological processes in rheumatoid arthritis and atherosclerosis

RA is characterized by a systemic inflammatory state, in which immune cells and soluble mediators play a crucial role. These inflammatory processes resemble those in other chronic inflammatory diseases, such as atherosclerosis. The chronic systemic inflammation in RA can be considered as an independent risk factor for the development of atherosclerosis, and represents an important field to investigate the reasons of the increase of acute cardiovascular events in RA. In the present review, we focused on several mediators of autoimmunity, inflammation and endothelial dysfunction, which can be considered the most promising targets to prevent atherogenesis in RA. Among several mediators, the pro-inflammatory cytokine TNF-alpha has been shown as a crucial factor to induce atherosclerosis in RA patients.

Mesenchymal cell targeting by TNF as a common pathogenic principle in chronic inflammatory joint and intestinal diseases

Tumor necrosis factor (TNF) is key to the pathogenesis of various arthritic diseases and inflammatory bowel disease (IBD). Anti-TNF therapies have proved successful in the clinical treatment of these diseases, but a mechanistic understanding of TNF function is still lacking. We have investigated early cellular mechanisms of TNF function in these diseases using an established TNF transgenic model, which develops a spondyloarthritis-like disease characterized by peripheral joint arthritis, sacroiliitis, enthesitis, and Crohn's-like IBD. Bone marrow grafting experiments demonstrated that development of arthritis requires TNF receptor I (TNFRI) expression in the radiation-resistant compartment, which is also known to be a sufficient target of TNF in the development of Crohn's-like IBD in the same model. Early activation of synovial fibroblasts and intestinal myofibroblasts could also be demonstrated by perturbed expression of matrix metalloproteases and their inhibitors. Notably, selective Cre/loxP-mediated TNFRI expression in mesenchymal cells resulted in a fully arthritic–spondyloarthritic and intestinal phenotype, indicating that mesenchymal cells are primary and sufficient targets of TNF in these pathologies. Our results offer a novel mechanistic perspective for TNF function in gut and joint pathologies and indicate early common cellular pathways that may also explain the often observed synovial–gut axis in human disease.

Metalloproteinase-9 deficiency protects against hepatic ischemia/reperfusion injury

Leukocyte transmigration across endothelial and extracellular matrix protein barriers is dependent on adhesion and focal matrix degradation events. In the present study we investigated the role of metalloproteinase-9 (MMP-9/gelatinase B) in liver ischemia/reperfusion (I/R) injury using MMP-9-deficient (MMP-9(-/-)) animals and mice treated with a specific anti-MMP-9 neutralizing antibody or with a broad gelatinase inhibitor for both MMP-9 and metalloproteinase-2 (MMP-2/gelatinase A). Compared to wild-type mice, MMP-9(-/-) mice and mice treated with an anti-MMP-9 antibody showed significantly reduced liver damage. In contrast, mice treated with a broad gelatinase inhibitor showed rather inferior protection against I/R injury and were characterized by persistent ongoing liver inflammation, suggesting that MMP-2 and MMP-9 may have distinct roles in this type of injury. MMP-9 was mostly detected in Ly-6G and macrophage antigen-1 leukocytes adherent to the vessel walls and infiltrating the damaged livers of wild-type mice after liver I/R injury. Leukocyte traffic and cytokine expression were markedly impaired in livers of MMP-9(-/-) animals and in livers of mice treated with anti-MMP-9 antibody after I/R injury; however, initiation of the endothelial adhesion cascades was similar in both MMP-9(-/-) and control livers. We also showed that MMP-9-specific inhibition disrupted neutrophil migration across fibronectin in transwell filters and depressed myeloperoxidase (MPO) activation in vitro.

CONCLUSION

These results support critical functions for MMP-9 in leukocyte recruitment and activation leading to liver damage. Moreover, they provide the rationale for identifying inhibitors to specifically target MMP-9 in vivo as a potential therapeutic approach in liver I/R injury.

Serum levels of matrix metalloproteinase 3 (stromelysin 1) for monitoring synovitis in rheumatoid arthritis

CONTEXT

Matrix metalloproteinase 3 (MMP-3) is expressed in synovial tissues and involved in cartilage destruction in rheumatoid arthritis and osteoarthritis.

OBJECTIVE

To study whether measurement of MMP-3 serum concentrations is useful to monitor the activity of rheumatoid synovitis.

DESIGN

Levels of MMP-3 in serum and synovial tissue samples obtained from 29 rheumatoid arthritis patients and 20 osteoarthritis patients were measured by the 1-step sandwich enzyme immunoassay system.

RESULTS

Levels of MMP-3 in the serum and synovial samples were significantly higher in rheumatoid arthritis than in osteoarthritis (P < .001), and the levels correlated directly with each other (r = 0.712, P < .001; N = 49). Immunohistochemistry demonstrated almost exclusive localization of MMP-3 to the lining cells in rheumatoid synovium. The immunoreactivity correlated directly with the scores of synovial inflammatory cell infiltration (r = 0.606, P < .001; n = 29) and the MMP-3 levels in the synovial tissues (r = 0.564, P = .001; n = 29) and those in the serum samples (r = 0.529, P = .003; n = 29) in rheumatoid arthritis. Levels of MMP-3 in rheumatoid serum samples dropped to low values at 1 and 2 weeks after total knee arthroplasty, while the levels of C-reactive protein increased at 1 week and the erythrocyte sedimentation rate and counts of white blood cells and platelets were unchanged at 1 and 2 weeks postoperative.

CONCLUSIONS

Our results demonstrate that MMP-3 levels in the serum of rheumatoid arthritis patients correlate with the levels produced by the synovial lining cells and suggest that the activity of rheumatoid synovitis can be monitored by measuring serum levels of MMP-3.

Serum pro-matrix metalloproteinase-3 as an indicator of disease activity and severity in rheumatoid arthritis: comparison with traditional markers

Matrix metalloproteinase-3 (MMP-3) production increases in rheumatoid arthritis (RA) and has been proposed as a marker of disease activity and joint damage. The aim of this cross-sectional study is to examine the usefulness of serum proMMP-3 as an indicator of disease activity and severity in comparison with erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP). Serum proMMP-3 was measured by a quantitative ELISA in 85 RA patients and 70 healthy subjects. Clinical and laboratory measures of disease activity and severity were obtained. Radiological joint damage was assessed by the method of Larsen. Serum proMMP-3 was significantly higher in RA patients than that in the healthy subjects. The active RA patients had significantly higher serum proMMP-3 than the inactive patients. Serum proMMP-3 was significantly correlated with some parameters of disease activity including swollen joints count, proximal interphalangeal joint score, morning stiffness, and Health Assessment Questionnaire; however, ESR and serum CRP were better correlated with all indicators of the disease activity than proMMP-3. The analysis of receiver operating characteristic supported that ESR and CRP had higher performance for reflection of activity compared to proMMP-3. There were no significant associations among Larsen score and proMMP-3, ESR, and CRP. Our results suggest that the cross-sectional measurement of serum proMMP-3 could not give additional information about RA disease activity compared to ESR and CRP, and could not give any information about joint damage.

Matrix metalloproteinase expression in the spondyloarthropathies

PURPOSE OF REVIEW

Expression of matrix metalloproteinases and their tissue inhibitors has been an active area of investigation in rheumatoid arthritis and osteoarthritis. Only recently have investigators started to study these factors in spondyloarthropathy. The purpose of this review is to summarize these recent findings.

RECENT FINDINGS

Multiple matrix metalloproteinases and their tissue inhibitors are expressed in the synovial fluid as well as serum samples of spondyloarthropathy patients. Their degrees of expression in the synovia correlate with parameters of arthritis activity such as cell infiltration. In the synovial fluids, the factor which is expressed in very high level is matrix metalloproteinase-3. Two separate cohorts demonstrate that serum levels of matrix metalloproteinase-3 correlate with disease activity in ankylosing spondylitis. Their usefulness appears to exceed those of erythrocyte sedimentation rate and C-reactive protein. Multiple studies also indicate that serum levels of matrix metalloproteinase-3 are suppressed when patients are treated with the anti-tumor necrosis factor-alpha antibody infliximab.

SUMMARY

New biomarkers are in demand for spondyloarthropathy in deciding whether patients would benefit from treatment with tumor necrosis factoralpha blockers, monitoring response to treatment, or predicting potential of joint damage if untreated. Recent studies show that among the matrix metalloproteinase and their tissue inhibitors, serum MMP-3 is the one with potential usefulness.

Urine cartilage oligomeric matrix protein (COMP) measurement is useful in discriminating the osteoarthritic Thoroughbreds

OBJECTIVE

To quantify the urinary concentration of cartilage oligomeric matrix protein (COMP), and to evaluate the relationship between urinary COMP concentration and the catabolic activity of synovial fluid (SF) in diseased horses.

METHODS

COMP in horse urine was detected by immunoblotting with a monoclonal antibody (mAb; 14G4) raised against equine COMP from articular cartilage. Urine and serum samples were obtained from 83 Thoroughbred horses with aseptic joint diseases (AJD, 79 horses) or septic joint diseases (SJD, four horses) at the time of anesthesia induction, and samples of SF were obtained during surgery. Control samples of urine (n=111) were collected from normal horses free of any orthopedic diseases after they had been racing. COMP concentration was determined in all samples using inhibition enzyme-linked immunosorbent assay (ELISA) with mAb 14G4. SF samples were also used for the quantification of gelatinase activity.

RESULTS

Positive bands of COMP fragments were determined on the immunoblots with mAb 14G4. The urinary COMP concentrations in AJD and SJD horses (1.02+/-0.75 and 1.55+/-1.17 microg/100mg creatinine, respectively) were significantly higher than normal (0.57+/-0.29 microg/100mg creatinine). In 55 horses with fractures in the AJD group there was a logarithmic relationship (r=-0.45, P<0.001) between the urinary and SF COMP measurements, while the urinary COMP level was positively correlated with matrix metalloproteinase (MMP)-2 and -9 activities (r=0.30, P<0.05 and r=0.51, P<0.001, respectively) in SF.

CONCLUSIONS

The urinary COMP assay with mAb 14G4 is useful for discriminating horses with osteoarthritis. The higher COMP levels in urine from such horses would be indicative of enhanced proteolytic activity, in addition to the increased COMP levels in the diseased joints.

Levels and Activation of Matrix Metalloproteinases in Aqueous Humor Are Elevated in Uveitis-Related Secondary Glaucoma

PURPOSE

To measure the levels of matrix metalloproteinase (MMP)-2 and tissue inhibitors of metalloproteinases (TIMP)-2 and to study the expression pattern and molecular forms of MMP-2, 8, 9, 13, and 14 and TIMP-1 and 2 in aqueous humor samples in cases of uveitis-related secondary glaucoma (USG) with a history of up to 20 years by comparison with primary open-angle glaucoma (POAG) and cataracts.

METHODS

33 aqueous humor samples were collected during intraocular surgery. MMP-2 and TIMP-2 levels were analyzed by enzyme-linked immunosorbent assay. Molecular forms and activation degrees of MMPs and TIMPs were analyzed by Western immunoblotting and zymography. The results were related to the clinical data.

RESULTS

Enzyme-linked immunosorbent assay measurements of both MMP-2 and TIMP-2 were statistically significantly increased in the USG samples relative to POAG and cataracts (P=0.002). In Western blotting all the MMPs showed increased expression and conversion to their active forms in USG, whereas in the POAG and cataract samples MMPs were found mainly in their latent forms. MMP-8, 9, 13, and 14 showed statistically significantly elevated expression in USG relative to POAG and cataracts on densitometric scanning of Western blots. On zymography, MMP-2 and 9 activation was significantly enhanced in USG compared with POAG and cataracts.

CONCLUSIONS

Increased expression of MMPs and their conversion to active forms is characteristics of the aqueous humor in USG, even with a very long history. This emphasizes the fact that increased MMP expression reflects inflammatory disease activity and is probably associated with the development of USG and its complications. Although intraocular pressure is elevated in both glaucoma types, MMP expression in POAG more closely resembles that in cataracts, and therefore the role of MMPs in USG differs very markedly from that in POAG.

Matrix metalloproteinase-9 and autoimmune diseases

Matrix metalloproteinases (also named matrixin or MMPs) are a major group of enzymes that regulate cell-matrix composition by using zinc for their proteolytic activities. They are essential for various normal biological processes such as embryonic development, morphogenesis, reproduction tissue resorption, and remodeling. Metalloproteinases also play a role in pathological processes including inflammation, arthritis, cardiovascular diseases, pulmonary diseases and cancer. Herein we review the involvement of MMP-9 in a variety of autoimmune diseases including systemic lupus erythematosus, Sjogren's syndrome, systemic sclerosis, rheumatoid arthritis, multiple sclerosis, polymyositis and atherosclerosis. MMP-9 plays either a primary or secondary role in each one of those autoimmune diseases by its up or down-regulation. It is not expressed constantly but rather is induced or suppressed by many regulating molecules. This feature of MMP-9 along with its involvement in disease pathogenesis turns it into a target for therapy of autoimmune diseases.

Altered plasma matrix metalloproteinase-9/tissue metalloproteinase-1 concentration during the early postoperative period in patients with colorectal cancer

BACKGROUND

The authors have previously demonstrated that insulin-like growth factor binding protein-3 (IGFBP-3) is depleted in plasma for 1 to 3 days after major open surgery (OS), but not after laparoscopic surgery (LS). After surgery, IGFP-3 cleavage occurs rapidly and is likely attributable to altered plasma proteolytic activity. This study aimed to assess plasma proteolysis after both open and closed colorectal resection and, if possible, to identify a protease/protease inhibitor system affected by surgery.

METHODS

Plasma from 88 patients with colorectal cancer (stages I-III) who underwent resection was obtained preoperatively (pre-OP) and on postoperative days (POD) 1 to 3. Plasma proteolytic activity was assessed via zymography. On the basis of the results, specific protease and protease inhibitor concentrations were next measured via enzyme-linked immunoassay (ELISA). Statistical analysis was performed using Wilcoxon's test.

RESULTS

Early after surgery, zymography showed a predominant band representing a 92-kDa gelatinase corresponding to a proform of matrix metalloproteinase-9 (MMP-9), a protease known to cleave IGFBP-3. In OS patients, the mean concentration of plasma MMP-9 was significantly higher on POD 1 than at pre-OP (p < 0.003). On POD 2 and 3, no differences were noted. In the LS group, the mean levels of MMP-9 before and after surgery were comparable. The levels of a natural MMP-9 inhibitor, tissue inhibitor of metalloproteinase-1 (TIMP-1), also were measured. In the OS group, the level of TIMP-1 was significantly higher on POD 1 (p < 0.0003) and POD 2 (p < 0.01) and 3 (p < 0.01) than at pre-OP. In the LS group, a smaller but significant increase in TIMP-1 levels was found between the pre-OP sample and the POD 1 (p < 0.01) and POD 2 (p < 0.01) samples. No difference was noted on POD 3 (p = 0.1).

CONCLUSIONS

Open surgery, but not laparoscopic surgery, is accompanied by a short-lived significant increase in MMP-9 levels, which likely accounts for the decrease in IGFBP-3 levels observed after OS. The transitory nature of MMP-9 imbalance may be attributable to the increase in TIMP-1 levels postoperatively.

The Examination of Rheumatoid Factor and Other Serum Markers in Rheumatoid Arthritis

Rheumatoid factor (IgM-RF) has been widely used to diagnose rheumatoid arthritis (RA) in clinical practice. We investigated the RA diagnostic performances of anti-cyclic citrullinated peptide antibody (anti-CCP), matrix metalloproteinase-3 (MMP-3), anti-agalactosyl IgG antibody (CA*RF), and anti-calpastatin antibody (ACA) in comparison with IgM-RF. Among 68 RA patients, IgM-RF was positive in 31 (45.6%) and negative in 37 (54.4%). In the IgM-RF-positive group, positivity in anti-CCP, CA*RF, and ACA was 97%, 100%, and 97%, respectively, although that in MMP-3 (74%) was inferior to the others. On the other hand, in the IgM-RF-negative group, positivity in anti-CCP, MMP-3, and ACA was 73%, 81%, and 86%, respectively, although that in CA*RF was only 59%. We conclude that the combination of IgM-RF and anti-CCP/ACA will provide an accurate diagnosis of RA in clinical practice.

Opposing regulatory roles of complement factor 5 in the development of bleomycin-induced pulmonary fibrosis

The mechanisms of idiopathic pulmonary fibrosis pathogenesis, a chronic and progressive interstitial lung disease, remain elusive. The complement system, a crucial arm of the innate immune response, plays a pivotal role in several pathological disorders; however, the contribution of individual complement components to lung fibrosis has not yet been examined. Complement factor 5 (C5) and its cleavage product C5a are critical mediators in inflammatory diseases. Thus, to evaluate the role of C5 in lung fibrosis, we compared congenic C5-sufficient and C5-deficient mice in a well-characterized murine model of bleomycin-induced pulmonary fibrosis. C5-deficient mice had an exaggerated inflammatory phenotype compared with C5-sufficient mice during acute bleomycin-induced lung injury. These findings suggest a protective and anti-inflammatory role for C5, which was linked to the regulation of matrix metalloproteinases involved in cell migration. In contrast, C5 had a detrimental effect during chronic stages of bleomycin-induced injury, indicating a profibrotic role for C5. This deleterious activity for C5 was associated with expression of the fibrogenic cytokine TGF-beta1 and matrix metalloproteinase-3, an important mediator in fibroblast contraction. Altogether, our data reveal novel and opposing roles for C5 in both inflammation and tissue repair. Furthermore, these findings provide insight into the development of new therapeutic strategies for idiopathic pulmonary fibrosis patients.

Synovial proinflammatory cytokines and their correlation with matrix metalloproteinase-3 expression in Behçet's disease. Does interleukin-1beta play a major role in Behçet's synovitis?

The objective of this study has been the well established fact that proinflammatory cytokines and metalloproteinases play a crucial role in the pathogenesis of chronic arthritis as well as the development of pannus, with the eventual erosive changes. Among the proinflammatory cytokines, interleukin-18 (IL-18) has been shown to contribute to the pathogenesis of chronic synovitis by increasing the secretion of interleukin-1beta (IL-1beta) and the tumor necrosis factor-alpha (TNF-alpha) and also stimulating angiogenesis. The aim of this study is to investigate the synovial IL-18, IL-1beta, TNF-alpha and matrix metalloproteinase-3 (MMP-3) levels in patients with Behçet's disease (BD), and compare them with the levels of patients with rheumatoid arthritis (RA) and osteoarthritis (OA). 30 patients with BD, 20 with RA, and 20 with OA were included in the study. The synovial levels of IL-18, IL-1beta, TNF-alpha and MMP-3 were detected using the two-step sandwich ELISA method. The synovial IL-18, TNF-alpha and MMP-3 levels were significantly higher in RA patients than patients with BD (P=0.004, 0.019, 0.025, respectively) and with OA (P=0.004, 0.045, 0.032, respectively). There were no differences, with respect to the cytokine levels, when patients with BD were compared with those with OA. Patients with RA and BD had higher IL-1beta levels than patients with OA (P=0.017, 0.013, respectively). However, no such difference was found for IL-1beta between BD and RA patients. Among patients with RA, positive correlations were found between TNF-alpha and MMP-3 (r=0.683, P=0.001). Our results showed that MMP-3 and proinflammatory cytokines, except IL-1beta, were expressed in relatively small quantities in Behçet's synovitis. Detection of the lower levels of these cytokines and metalloproteinases might explain the non-erosive character of Behçet's arthritis. We suggest that IL-1beta may be involved in the pathogenesis of Behçet's synovitis.

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.

MMP protein and activity levels in synovial fluid from patients with joint injury, inflammatory arthritis, and osteoarthritis

OBJECTIVE

To determine protein and activity levels of matrix metalloproteinases 1 and 3 (MMP-1 and MMP-3) in synovial fluid of patients with knee joint injury, primary osteoarthritis, and acute pyrophosphate arthritis (pseudogout).

METHODS

Measurements were done on knee synovial fluid obtained in a cross sectional study of cases of injury (n = 283), osteoarthritis (n = 105), and pseudogout (n = 65), and in healthy controls (n = 35). Activity of MMP-1 and MMP-3 in alpha(2) macroglobulin complexes was measured using specific low molecular weight fluorogenic substrates. ProMMP-1, proMMP-3, and TIMP-1 (tissue inhibitor of metalloproteinase 1) were quantified by immunoassay.

RESULTS

Mean levels of proMMP-1, proMMP-3, and TIMP-1 were increased in injury, osteoarthritis, and pseudogout compared with controls. MMP-1 activity was increased in pseudogout and injury groups over control levels, whereas MMP-3 activity was increased only in the pseudogout group. The increase in MMP-1 activity coincided with a decrease in TIMP-1 levels in the injury group.

CONCLUSIONS

Patients with joint injury have a persistent increase in proMMP-1 and proMMP-3 in synovial fluid and an increase in activated MMPs, which are not inhibited by TIMP. The differences in activation and inhibition patterns between the study groups are consistent with disease specific patterns of MMP activation and/or inhibition in joint pathology.

Induction of host matrix metalloproteinases by Borrelia burgdorferi differs in human and murine lyme arthritis

Matrix metalloproteinases (MMPs) are induced from host tissues in response to Borrelia burgdorferi. Upregulation of MMPs may play a role in the dissemination of the organism through extracellular matrix tissues, but it can also result in destructive pathology. Although mice are a well-accepted model for Lyme arthritis, there are significant differences compared to human disease. We sought to determine whether MMP expression could account for some of these differences. MMP expression patterns following B. burgdorferi infection were analyzed in primary human chondrocytes, synovial fluid samples from patients with Lyme arthritis, and cartilage tissue from Lyme arthritis-susceptible and -resistant mice by using a gene array, real-time PCR, an enzyme-linked immunosorbent assay, and immunohistochemistry. B. burgdorferi infection significantly induced transcription of MMP-1, -3, -13, and -19 from primary human chondrocyte cells. Transcription of MMP-10 and tissue inhibitor of metalloprotease 1 was increased with B. burgdorferi infection, but protein expression was only minimally increased. The synovial fluid levels of MMPs from patients with high and low spirochete burdens were consistent with results seen in the in vitro studies. B. burgdorferi-susceptible C3H/HeN mice infected with B. burgdorferi showed induction of MMP-3 and MMP-19 but no other MMP or tissue inhibitor of metalloprotease. As determined by immunohistochemistry, MMP-3 expression was increased only in chondrocytes near the articular surface. The levels of MMPs were significantly lower in the more Lyme arthritis-resistant BALB/c and C57BL/6 mice. Differences between human and murine Lyme arthritis may be related to the lack of induction of collagenases, such MMP-1 and MMP-13, in mouse joints.