Similarities in the pathologies of autoimmune diseases and cancer have been noted for at least 30 years. Inflammatory cytokines and growth factors mediate cell proliferation, and proteinases, especially the collagenase, Matrix Metalloproteinase-1 (MMP-1), contribute to disease progression by remodeling the extracellular matrix and modulating the microenvironment. This review focuses on two cancers (melanoma and breast) and on the autoimmune disorder, rheumatoid arthritis (RA), and discusses the activated stromal cells found in these diseases. MMP-1 was originally thought to function only to degrade interstitial collagens, but recent studies have revealed novel roles for MMP-1 involving the G protein-coupled receptors: the chemokine receptor, CXCR-4, and Protease Activated Receptor-1 (PAR-1). Cooperativity between MMP-1 and CXCR4/SDF-1 signaling influences the behavior of activated fibroblasts in both RA and cancer. Further, MMP-1 is a vital part of an autocrine/paracrine MMP-1/PAR-1 signal transduction axis, a function that amplifies its potential to remodel the matrix and to modify cell behavior. Finally, new therapeutic agents directed at MMP-1 and G protein-coupled receptors are emerging. Even though these agents are more specific in their targets than past therapies, these targets are often shared between RA and cancer, underscoring fundamental similarities between autoimmune disorders and some cancers.
rheumatoid arthritis; collagenase; CXCR4; PAR-1; synovial fibroblasts; carcinoma associated fibroblasts; endothelial cells
Matrix metalloproteinase-13 (collagenase-3), a member of the family of matrix metalloproteinases (MMPs), plays a major pathological role in the cartilage destruction of arthritis. A dramatic up-regulation of MMP-13 by inflammatory cytokines such as interleukin (IL)-1β or by fibronectin fragments has been observed in chondrocytes. In this study, we investigated the inhibitory effects of insulin-like growth factor-1 (IGF-1) and osteogenic protein-1 (OP-1) on the expression of MMP-13, which was induced by fibronectin fragment or IL-1β in human immortalized or human primary chondrocytes. IGF-1 and OP-1 each significantly reduced the basal level as well as fibronectin fragment- or IL-1β-stimulated transcription of the MMP-13 gene in a dose-dependent fashion with the corresponding decreases in the protein level of MMP-13. The most prominent suppressive effect was observed by the combination of IGF-1 and OP-1, which decreased the basal promoter activity by 60% and almost completely abrogated the fibronectin fragment-stimulated MMP-13 promoter activity. OP-1 was found to enhance mRNA levels of IGF-1 and the IGF-1 receptor, the latter of which appeared to be responsible for the combined effect of IGF-1 and OP-1. The suppressive effect of IGF-1 and OP-1 on MMP-13 expression was due in part to down-regulation of the expression of pro-inflammatory cytokines and the activity of their intermediate molecules, including NF-κB and AP-1 factors. We propose that IGF-1 and OP-1 could be key physiological regulators of MMP-13 gene expression and that the combination of IGF-1 and OP-1 may be useful in controlling the excess catabolic activity in arthritis.
Matrix metalloproteinases (MMPs) are zinc-containing endopeptidases. They degrade proteins by cleavage of peptide bonds. More than twenty MMPs have been identified and are separated into six groups based on their structure and substrate specificity (collagenases, gelatinases, membrane type [MT-MMP], stromelysins, matrilysins, and others). MMPs play a critical role in cell invasion, cartilage degradation, tissue remodeling, wound healing, and embryogenesis. They therefore participate in both normal processes and in the pathogenesis of many diseases, such as rheumatoid arthritis, cancer, or chronic obstructive pulmonary disease1-6. Here, we will focus on MMP-2 (gelatinase A, type IV collagenase), a widely expressed MMP. We will demonstrate how to detect MMP-2 in cell culture supernatants by zymography, a commonly used, simple, and yet very sensitive technique first described in 1980 by C. Heussen and E.B. Dowdle7-10. This technique is semi-quantitative, it can therefore be used to determine MMP levels in test samples when known concentrations of recombinant MMP are loaded on the same gel11.
Solutions containing MMPs (e.g. cell culture supernatants, urine, or serum) are loaded onto a polyacrylamide gel containing sodium dodecyl sulfate (SDS; to linearize the proteins) and gelatin (substrate for MMP-2). The sample buffer is designed to increase sample viscosity (to facilitate gel loading), provide a tracking dye (bromophenol blue; to monitor sample migration), provide denaturing molecules (to linearize proteins), and control the pH of the sample. Proteins are then allowed to migrate under an electric current in a running buffer designed to provide a constant migration rate. The distance of migration is inversely correlated with the molecular weight of the protein (small proteins move faster through the gel than large proteins do and therefore migrate further down the gel). After migration, the gel is placed in a renaturing buffer to allow proteins to regain their tertiary structure, necessary for enzymatic activity. The gel is then placed in a developing buffer designed to allow the protease to digest its substrate. The developing buffer also contains p-aminophenylmercuric acetate (APMA) to activate the non-proteolytic pro-MMPs into active MMPs. The next step consists of staining the substrate (gelatin in our example). After washing the excess dye off the gel, areas of protease digestion appear as clear bands. The clearer the band, the more concentrated the protease it contains. Band staining intensity can then be determined by densitometry, using a software such as ImageJ, allowing for sample comparison.
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.
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.
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.
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.
Degradation of collagenous extracellular matrix by collagenase 1 (also known as matrix metalloproteinase 1 [MMP-1]) plays a role in the pathogenesis of various destructive disorders, such as rheumatoid arthritis, chronic ulcers, and tumor invasion and metastasis. Here, we have investigated the role of distinct mitogen-activated protein kinase (MAPK) pathways in the regulation of MMP-1 gene expression. The activation of the extracellular signal-regulated kinase 1 (ERK1)/ERK2 (designated ERK1,2) pathway by oncogenic Ras, constitutively active Raf-1, or phorbol ester resulted in potent stimulation of MMP-1 promoter activity and mRNA expression. In contrast, activation of stress-activated c-Jun N-terminal kinase and p38 pathways by expression of constitutively active mutants of Rac, transforming growth factor β-activated kinase 1 (TAK1), MAPK kinase 3 (MKK3), or MKK6 or by treatment with arsenite or anisomycin did not alone markedly enhance MMP-1 promoter activity. Constitutively active MKK6 augmented Raf-1-mediated activation of the MMP-1 promoter, whereas active mutants of TAK1 and MKK3b potently inhibited the stimulatory effect of Raf-1. Activation of p38 MAPK by arsenite also potently abrogated stimulation of MMP-1 gene expression by constitutively active Ras and Raf-1 and by phorbol ester. Specific activation of p38α by adenovirus-delivered constitutively active MKK3b resulted in potent inhibition of the activity of ERK1,2 and its upstream activator MEK1,2. Furthermore, arsenite prevented phorbol ester-induced phosphorylation of ERK1,2 kinase-MEK1,2, and this effect was dependent on p38-mediated activation of protein phosphatase 1 (PP1) and PP2A. These results provide evidence that activation of signaling cascade MKK3-MKK3b→p38α blocks the ERK1,2 pathway at the level of MEK1,2 via PP1-PP2A and inhibits the activation of MMP-1 gene expression.
Interleukin-1 (IL-1), IL-17 and tumor necrosis factor alpha (TNF-α) are the main proinflammatory cytokines implicated in cartilage breakdown by matrix metalloproteinase (MMPs) in arthritic joints. We studied the impact of an anti-neoplastic antibiotic, mithramycin, on the induction of MMPs in chondrocytes. MMP-3 and MMP-13 gene expression induced by IL-1β, TNF-α and IL-17 was downregulated by mithramycin in human chondrosarcoma SW1353 cells and in primary human and bovine femoral head chondrocytes. Constitutive and IL-1-stimulated MMP-13 levels in bovine and human cartilage explants were also suppressed. Mithramycin did not significantly affect the phosphorylation of the mitogen-activated protein kinases, extracellular signal-regulated kinase, p38 and c-Jun N-terminal kinase. Despite effective inhibition of MMP expression by mithramycin and its potential to reduce cartilage degeneration, the agent might work through multiple unidentified mechanisms.
OBJECTIVES--To investigate whether interstitial collagenase (MMP-1) concentration in synovial fluid can be useful as a marker for disease activity in rheumatoid arthritis (RA), to determine the main route by which collagenase degrades the matrix of articular cartilage, and to investigate if an imbalance between metalloproteinases (MMPs) and tissue inhibitor of metalloproteinases (TIMP) is responsible for the activity of MMPs in RA. METHODS--Collagenase concentrations were measured in synovial fluid and paired serum samples using a specific sandwich enzyme linked immunosorbent assay. Collagenase activities were also assayed in synovial fluid samples. Synovial tissues obtained from the same patient were examined by immunohistochemical staining and the numbers of cells expressing collagenase were counted. RESULTS--Collagenase concentrations in synovial fluid did not correlate with C reactive protein and collagenase levels in serum, but did correlate positively with the degree of synovial inflammation, and increased with increasing numbers of cells identified as expressing collagenase in synovial tissue. Collagenase activities did not correlate with TIMP-1 concentrations, but did correlate strongly with the ratios of collagenase concentration to TIMP-1 (r = 0.73). CONCLUSION--The collagenase concentration in synovial fluid cannot be used as a marker for systemic disease activity, but can be used as a marker for the degree of synovial inflammation in the joint from which the sample is aspirated. In advanced RA, most of the collagenase is probably produced in synovial lining cells and released into synovial fluid, where it degrades the matrix of articular cartilage. An imbalance between MMP and TIMP may be of importance in the degradation of extracellular matrix of articular cartilage in RA.
Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by destruction of bone and cartilage, which is mediated, in part, by synovial fibroblasts. Matrix metalloproteinases (MMPs) are a large family of proteolytic enzymes responsible for matrix degradation. Macrophage migration inhibitory factor (MIF) is a cytokine that induces the production of a large number of proinflammatory molecules and has an important role in the pathogenesis of RA by promoting inflammation and angiogenesis.
In the present study, we determined the role of MIF in RA synovial fibroblast MMP production and the underlying signaling mechanisms. We found that MIF induces RA synovial fibroblast MMP-2 expression in a time-dependent and concentration-dependent manner. To elucidate the role of MIF in MMP-2 production, we produced zymosan-induced arthritis (ZIA) in MIF gene-deficient and wild-type mice. We found that MMP-2 protein levels were significantly decreased in MIF gene-deficient compared with wild-type mice joint homogenates. The expression of MMP-2 in ZIA was evaluated by immunohistochemistry (IHC). IHC revealed that MMP-2 is highly expressed in wild-type compared with MIF gene-deficient mice ZIA joints. Interestingly, synovial lining cells, endothelial cells, and sublining nonlymphoid mononuclear cells expressed MMP-2 in the ZIA synovium. Consistent with these results, in methylated BSA (mBSA) antigen-induced arthritis (AIA), a model of RA, enhanced MMP-2 expression was also observed in wild-type compared with MIF gene-deficient mice joints. To elucidate the signaling mechanisms in MIF-induced MMP-2 upregulation, RA synovial fibroblasts were stimulated with MIF in the presence of signaling inhibitors. We found that MIF-induced RA synovial fibroblast MMP-2 upregulation required the protein kinase C (PKC), c-jun N-terminal kinase (JNK), and Src signaling pathways. We studied the expression of MMP-2 in the presence of PKC isoform-specific inhibitors and found that the PKCδ inhibitor rottlerin inhibits MIF-induced RA synovial fibroblast MMP-2 production. Consistent with these results, MIF induced phosphorylation of JNK, PKCδ, and c-jun. These results indicate a potential novel role for MIF in tissue destruction in RA.
Degradation of ECM, particularly interstitial collagen, promotes plaque instability, rendering atheroma prone to rupture. Previous studies implicated matrix metalloproteinases (MMPs) in these processes, suggesting that dysregulated MMP activity, probably due to imbalance with endogenous inhibitors, promotes complications of atherosclerosis. We report here that the serine proteinase inhibitor tissue factor pathway inhibitor-2 (TFPI-2) can function as an MMP inhibitor. TFPI-2 diminished the ability of the interstitial collagenases MMP-1 and MMP-13 to degrade triple-helical collagen, the primary load-bearing molecule of the ECM within human atheroma. In addition, TFPI-2 also reduced the activity of the gelatinases MMP-2 and MMP-9. In contrast to the “classical” tissue inhibitors of MMPs (TIMPs), TFPI-2 expression in situ correlated inversely with MMP levels in human atheroma. TFPI-2 colocalized primarily with smooth muscle cells in the normal media as well as the plaque’s fibrous cap. Conversely, the macrophage-enriched shoulder region, the prototypical site of matrix degradation and plaque rupture, stained only weakly for TFPI-2 but intensely for gelatinases and interstitial collagenases. Evidently, human mononuclear phagocytes, an abundant source of MMPs within human atheroma, lost their ability to express this inhibitor during differentiation in vitro. These findings establish a new, anti-inflammatory function of TFPI-2 of potential pathophysiological significance for human diseases, including atherosclerosis.
Fibroblast growth factor – 2 (FGF2) and interleukin – 1β IL-1β) stimulate the expression of matrix metalloproteinases (MMPs) in articular chondrocytes, which may contribute to cartilage degradation and development of osteoarthritis. Histone deacetylases (HDACs) have recently been implicated in the regulation of MMP gene expression. To investigate the functional involvement of HDACs in the signaling pathway of FGF2 and IL-1β, we examined the effects of HDAC inhibition on activities of FGF2 or IL-1β on gene expression of MMP-1, MMP-3, MMP-13, a disintegrin and metalloproteinase with thrombospondin motifs – 5 (ADAMTS5), collagen type II, and aggrecan. Human articular chondrocyte cultures were treated with FGF2 or IL-1β in the presence or absence of HDAC inhibitor (trichostatin A, TSA). Gene expression levels after treatments were assessed using quantitative real time PCR. Results showed that FGF2 and IL-1β both increased MMP-1 and -13 expression, while IL-1βalso increased MMP-3 mRNA levels. These effects were attenuated in the presence of TSA in a dose dependent manner. In contrast to the effects on MMPs, FGF2 decreased mRNA levels of ADAMTS–5, which was not affected by HDAC inhibition. FGF2, IL-1β, and TSA inhibited expression of aggrecan, while TSA also decreased mRNA levels of collagen type II. These findings showed that HDAC inhibition antagonized FGF2 and IL-1β induced MMP expression. Combination of FGF2 and the HDAC inhibitor decreases both anabolic and catabolic genes, which may slow the cartilage turnover and be beneficial for maintaining cartilage integrity.
Fibroblast growth factor; interleukin –1β; histone deacetylase; matrix metalloproteinase; articular chondrocyte; trichostatin A
Matrix metalloproteinases (MMPs) participate in extracellular matrix remodeling and degradation and have been implicated in playing important roles during organ development and pathological processes. Although it has been hypothesized for > 30 years that collagenase activities are responsible for collagen degradation during tadpole tail resorption, none of the previously cloned amphibian MMPs have been biochemically demonstrated to be collagenases. Here, we report a novel matrix metalloproteinase gene from metamorphosing Xenopus laevis tadpoles. In vitro biochemical studies demonstrate that this Xenopus enzyme is an interstitial collagenase and has an essentially identical enzymatic activity toward a collagen substrate as the human interstitial collagenase. Sequence comparison of this enzyme to other known MMPs suggests that the Xenopus collagenase is not a homologue of any known collagenases but instead represents a novel collagenase, Xenopus collagenase-4 (xCol4, MMP-18). Interestingly, during development, xCol4 is highly expressed only transiently in whole animals, at approximately the time when tadpole feeding begins, suggesting a role during the maturation of the digestive tract. More importantly, during metamorphosis, xCol4 is regulated in a tissue-dependent manner. High levels of its mRNA are present as the tadpole tail resorbs. Similarly, its expression is elevated during hindlimb morphogenesis and intestinal remodeling. In addition, when premetamorphic tadpoles are treated with thyroid hormone, the causative agent of metamorphosis, xCol4 expression is induced in the tail. These results suggest that xCol4 may facilitate larval tissue degeneration and adult organogenesis during amphibian metamorphosis.
The extracellular matrix is a dynamic environment that constantly undergoes remodelling and degradation during vital physiological processes such as angiogenesis, wound healing, and development. Unbalanced extracellular matrix breakdown is associated with many diseases such as arthritis, cancer and fibrosis. Interstitial collagen is degraded by matrix metalloproteinases with collagenolytic activity by MMP-1, MMP-8 and MMP-13, collectively known as the collagenases. Matrix metalloproteinase 1 (MMP-1) plays a pivotal role in degradation of interstitial collagen types I, II, and III. Here, we report the crystal structure of the active form of human MMP-1 at 2.67 Å resolution. This is the first MMP-1 structure that is free of inhibitor and a water molecule essential for peptide hydrolysis is observed coordinated with the active site zinc. Comparing this structure with the human proMMP-1 shows significant structural differences, mainly in the relative orientation of the hemopexin domain, between the pro form and active form of the human enzyme.
MMP, matrix metalloproteinase; ECM, extracellular matrix; matrix metalloproteinases; fibroblast collagenase; collagen; X-ray crystallography; inhibitor-free
Matrix Metalloproteinases (MMPs) comprise a family of more than 20 members, each with the ability to degrade components of the extracellular matrix. The interstitial collagenases have the unique capacity to degrade the stromal collagens, types I, II and III, the body's most abundant proteins. These collagenases include MMP-1, MMP-8, MMP-13 and MMP-14. MMP-1, with a very broad expression pattern, has major roles in mediating matrix destruction in many diseases. We have described a single nucleotide polymorphism (SNP) in the MMP-1 promoter that augments transcription. This SNP is the presence or absence of an extra guanine (G) at -1607 bp, which creates the sequence 5'-GGAA-3'(2G allele), and which is an ETS binding site. Compared to the 1G allele (5'-GAA-3'), the 2G SNP is associated with enhanced transcription of MMP-1 and increased enzymatic activity.
Although murine systems are often used to model human diseases, mice have only distant homologues of human MMP-1. Therefore, we used a technique for the targeted insertion of a single copy of a gene at the HPRT locus to compare expression of the 1G and 2G alleles. We generated transgenic mice with -4372 bp of the human MMP-1 promoter containing either the 1G or 2G SNP in front of the Lac Z (E.coli ß-galactosidase) gene. We measured relative expression of the transgenes in vitro in embryonic stem (ES) cells and in fibroblasts derived from embryonic mice. Our data show modest constitutive expression of ß-galactosidase mRNA and protein from these alleles, with the 2G allele more transcriptionally active than the 1G allele. We conclude that these mice represent a model for integration of a single copy of the human MMP-1 promoter into the murine genome, and could be used to study MMP-1 gene expression in a murine system.
mRNA; ß-galactosidase; gene expression; single nucleotide polymorphism; fibroblasts
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.
allelic polymorphism; matrix metalloproteinase; radiographic progression; rheumatoid arthritis
Secretory phospholipase A2 (sPLA2) and matrix metalloproteinase (MMP) inhibitors are potent modulators of inflammation with therapeutic potential, but have limited efficacy in rheumatoid arthritis (RA). The objective of this study was to understand the inhibitory mechanism of phospholipase inhibitor from python (PIP)-18 peptide in cultured synovial fibroblasts (SF), and to evaluate its therapeutic potential in a human tumor necrosis factor (hTNF)-driven transgenic mouse (Tg197) model of arthritis.
Gene and protein expression of sPLA2-IIA, MMP-1, MMP-2, MMP-3, MMP-9, tissue inhibitor of metalloproteinase (TIMP)-1, and TIMP-2 were analyzed by real time PCR and ELISA respectively, in interleukin (IL)-1β stimulated rheumatoid arthritis (RA) and osteoarthritis (OA) synovial fibroblasts cells treated with or without inhibitors of sPLA2 (PIP-18, LY315920) or MMPs (MMP Inhibitor II). Phosphorylation status of mitogen-activated protein kinase (MAPK) proteins was examined by cell-based ELISA. The effect of PIP-18 was compared with that of celecoxib, methotrexate, infliximab and antiflamin-2 in Tg197 mice after ip administration (thrice weekly for 5 weeks) at two doses (10, 30 mg/kg), and histologic analysis of ankle joints. Serum sPLA2 and cytokines (tumor necrosis factor (TNF)α, IL-6) were measured by Escherichia coli (E coli) assay and ELISA, respectively.
PIP-18 inhibited sPLA2-IIA production and enzymatic activity, and suppressed production of MMPs in IL-1β-induced RA and OA SF cells. Treatment with PIP-18 blocked IL-1β-induced p38 MAPK phosphorylation and resulted in attenuation of sPLA2-IIA and MMP mRNA transcription in RA SF cells. The disease modifying effect of PIP-18 was evidenced by significant abrogation of synovitis, cartilage degradation and bone erosion in hTNF Tg197 mice.
Our results demonstrate the benefit that can be gained from using sPLA2 inhibitory peptide for RA treatment, and validate PIP-18 as a potential therapeutic in a clinically relevant animal model of human arthritis.
Members of the matrix metalloproteinase (MMP) family of proteases are required for the degradation of the basement membrane and extracellular matrix in both normal and pathological conditions. In vitro, MT1-MMP (MMP-14, membrane type-1-MMP) expression is higher in more invasive human breast cancer (HBC) cell lines, whilst in vivo its expression has been associated with the stroma surrounding breast tumours. MMP-1 (interstitial collagenase) has been associated with MDA-MB-231 invasion in vitro, while MMP-3 (stromelysin-1) has been localised around invasive cells of breast tumours in vivo. As MMPs are not stored intracellularly, the ability to localise their expression to their cells of origin is difficult.
We utilised the unique in situ-reverse transcription-polymerase chain reaction (IS-RT-PCR) methodology to localise the in vitro and in vivo gene expression of MT1-MMP, MMP-1 and MMP-3 in human breast cancer. In vitro, MMP induction was examined in the MDA-MB-231 and MCF-7 HBC cell lines following exposure to Concanavalin A (Con A). In vivo, we examined their expression in archival paraffin embedded xenografts derived from a range of HBC cell lines of varied invasive and metastatic potential. Mouse xenografts are heterogenous, containing neoplastic human parenchyma with mouse stroma and vasculature and provide a reproducible in vivo model system correlated to the human disease state.
In vitro, exposure to Con A increased MT1-MMP gene expression in MDA-MB-231 cells and decreased MT1-MMP gene expression in MCF-7 cells. MMP-1 and MMP-3 gene expression remained unchanged in both cell lines. In vivo, stromal cells recruited into each xenograft demonstrated differences in localised levels of MMP gene expression. Specifically, MDA-MB-231, MDA-MB-435 and Hs578T HBC cell lines are able to influence MMP gene expression in the surrounding stroma.
We have demonstrated the applicability and sensitivity of IS-RT-PCR for the examination of MMP gene expression both in vitro and in vivo. Induction of MMP gene expression in both the epithelial tumour cells and surrounding stromal cells is associated with increased metastatic potential. Our data demonstrate the contribution of the stroma to epithelial MMP gene expression, and highlight the complexity of the role of MMPs in the stromal-epithelial interactions within breast carcinoma.
OBJECTIVE—Matrix metalloproteinases (MMPs) are expressed in joint tissues of patients with rheumatoid arthritis (RA) and osteoarthritis (OA). The objective of this study was to define the steady state levels of seven different MMPs and two tissue inhibitors of metalloproteinases (TIMPs) as well as the potential metalloproteinase activity in the synovial fluid (SF) to provide more insight into the role of MMPs in cartilage destruction in RA and OA.
METHODS—Levels of MMP-1, MMP-2, MMP-3, MMP-7, MMP-8, MMP-9, MMP-13, TIMP-1, and TIMP-2 in SF aspirated from knee joints of 97 patients with RA and 103 patients with OA were measured by the corresponding one step sandwich enzyme immunoassays. Proteolytic activity of MMPs in these SFs was examined in an assay using [3H]carboxymethylated transferrin substrate in the presence of inhibitors of serine and cysteine proteinases after activation with p-aminophenylmercuric acetate (APMA). Destruction of RA knee joints was radiographically evaluated.
RESULTS—Levels of MMP-1, MMP-2, MMP-3, MMP-8, and MMP-9 were significantly higher in RA SF than in OA SF. MMP-7 and MMP-13 were detectable in more than 45% of RA SFs and in less than 20% of OA SFs, respectively. Among the MMPs examined, MMP-3 levels were extremely high compared with those of other MMPs. Direct correlations were seen between the levels of MMP-1 and MMP-3 and between those of MMP-8 and MMP-9 in RA SF. Although the levels of MMP-1 and MMP-3 increased even in the early stage of RA, those of MMP-8 and MMP-9 were low in the early stage and increased with the progression of RA. Molar ratios of the total amounts of the MMPs to those of the TIMPs were 5.2-fold higher in patients with RA than in OA, which was significant. APMA-activated metalloproteinase activity in SF showed a similar result, and a direct correlation was seen between the molar ratios and the activity in RA SF.
CONCLUSIONS—Our results show that high levels of MMP-1, MMP-2, MMP-3, MMP-8, MMP-9, and TIMP-1 are present in RA SF and suggest that once these MMPs are fully activated, they have an imbalance against TIMPs, which may contribute to the cartilage destruction in RA.
Infections of body tissue by Staphylococcus aureus are quickly followed by degradation of connective tissue. Patients with rheumatoid arthritis are more prone to S. aureus-mediated septic arthritis. Various types of collagen form the major structural matrix of different connective tissues of the body. These different collagens are degraded by specific matrix metalloproteinases (MMPs) produced by fibroblasts, other connective tissue cells, and inflammatory cells that are induced by interleukin-1 (IL-1) and tumor necrosis factor (TNF). To determine the host's contribution in the joint destruction of S. aureus-mediated septic arthritis, we analyzed the MMP expression profile in human dermal and synovial fibroblasts upon exposure to culture supernatant and whole cell lysates of S. aureus. Human dermal and synovial fibroblasts treated with cell lysate and filtered culture supernatants had significantly enhanced expression of MMP-1, MMP-2, MMP-3, MMP-7, MMP-10, and MMP-11 compared with the untreated controls (p < 0.05). In the S. aureus culture supernatant, the MMP induction activity was identified to be within the molecular-weight range of 30 to >50 kDa. The MMP expression profile was similar in fibroblasts exposed to a combination of IL-1/TNF. mRNA levels of several genes of the mitogen-activated protein kinase (MAPK) signal transduction pathway were significantly elevated in fibroblasts treated with S. aureus cell lysate and culture supernatant. Also, tyrosine phosphorylation was significantly higher in fibroblasts treated with S. aureus components. Tyrosine phosphorylation and MAPK gene expression patterns were similar in fibroblasts treated with a combination of IL-1/TNF and S. aureus. Mutants lacking staphylococcal accessory regulator (Sar) and accessory gene regulator (Agr), which cause significantly less severe septic arthritis in murine models, were able to induce expression of several MMP mRNA comparable with that of their isogenic parent strain but induced notably higher levels of tissue inhibitors of metalloproteinases (TIMPs). To our knowledge, this is the first report of induction of multiple MMP/TIMP expression from human dermal and synovial fibroblasts upon S. aureus treatment. We propose that host-derived MMPs contribute to the progressive joint destruction observed in S. aureus-mediated septic arthritis.
The rheumatic diseases continue to represent a significant healthcare burden in the 21st century. However, despite the best standard of care and recent therapeutic advances it is still not possible to consistently prevent the progressive joint destruction that leads to chronic disability. In rheumatoid arthritis and osteoarthritis this progressive cartilage and bone destruction is considered to be driven by an excess of the matrix metalloproteinase (MMP) enzymes. Consequently, a great number of potent small molecule MMP inhibitors have been examined. Several MMP inhibitors have entered clinical trials as a result of impressive data in animal models, although only one MMP inhibitor, Ro32-3555 (Trocade), a collagenase selective inhibitor, has been fully tested in the clinic, but it did not prevent progression of joint damage in patients with rheumatoid arthritis.
The key stages and challenges associated with the development of an MMP inhibitor in the rheumatic diseases are presented below with particular reference to Trocade. It is concluded that the future success of MMP inhibitors necessitates a greater understanding of the joint destructive process and it is hoped that their development may be accompanied with clearer, more practical, outcome measures to test these drugs for, what remains, an unmet medical need.
Collagenase 3 (MMP-13) is a recently identified member of the matrix metalloproteinase (MMP) gene family that is expressed at high levels in diverse human carcinomas and in articular cartilage from arthritic patients. In addition to its expression in pathological conditions, collagenase 3 has been detected in osteoblasts and hypertrophic chondrocytes during fetal ossification. In this work, we have evaluated the possibility that Cbfa1 (core binding factor 1), a transcription factor playing a major role in the expression of osteoblastic specific genes, is involved in the expression of collagenase 3 during bone formation. We have functionally characterized a Cbfa motif present in the promoter region of collagenase 3 gene and demonstrated, by cotransfection experiments and gel mobility shift assays, that this element is involved in the inducibility of the collagenase 3 promoter by Cbfa1 in osteoblastic and chondrocytic cells. Furthermore, overexpression of Cbfa1 in osteoblastic cells unable to produce collagenase 3 leads to the expression of this gene after stimulation with transforming growth factor β. Finally, we show that mutant mice deficient in Cbfa1, lacking mature osteoblasts but containing hypertrophic chondrocytes which are also a major source of collagenase 3, do not express this protease during fetal development. These results provide in vivo evidence that collagenase 3 is a target of the transcriptional activator Cbfa1 in these cells. On the basis of these transcriptional regulation studies, together with the potent proteolytic activity of collagenase 3 on diverse collagenous and noncollagenous bone and cartilage components, we proposed that this enzyme may play a key role in the process of bone formation and remodeling.
A hallmark of rheumatoid arthritis (RA) is invasion of the synovial pannus into cartilage and this step requires degradation of the collagen matrix. The aim of this study was to explore the role of one of the collagen-degrading matrix metalloproteinases (MMPs), membrane-type 1 MMP (MT1-MMP), in synovial pannus invasiveness.
Expression and localization of MT1-MMP in human RA pannus were investigated by Western blot analysis of primary synovial cells and immunohistochemistry of RA joints specimens. The functional role of MT1-MMP was analyzed by 3D collagen invasion assays and a cartilage invasion assay in the presence or absence of tissue inhibitor of metalloproteinase (TIMP)-1, TIMP-2, or GM6001. The effect of adenoviral expression of a dominant negative MT1-MMP construct lacking a catalytic domain was also examined.
MT1-MMP was highly expressed at the pannus-cartilage junction of RA joints. Freshly isolated rheumatoid synovial tissues and isolated RA synovial fibroblasts invaded into a 3D collagen matrix in an MT1-MMP-dependent manner. Invasion was blocked by TIMP-2 and GM6001, but not by TIMP-1. It was also inhibited by the over-expression of a dominant negative MT1-MMP which inhibits collagenolytic activity and proMMP-2 activation by MT1-MMP on the cell surface. Synovial fibroblasts also invaded into cartilage in an MT1-MMP-dependent manner. This process was further enhanced by removing aggrecan from the cartilage matrix.
MT1-MMP is an essential collagen-degrading proteinase during pannus invasion in human RA. Specific inhibition of MT1-MMP-dependent invasion may form a novel therapeutic strategy for RA.
MT1-MMP; synovial pannus; rheumatoid arthritis
Matrix metalloproteinases (MMPs) are proteolytic enzymes that degrade various components of the extracellular matrix (ECM). MMPs could also regulate the activity of several non-ECM bioactive substrates, and consequently affect different cellular functions. Members of the MMPs family include collagenases, gelatinases, stromelysins, matrilysins, membrane-type MMPs and others. Pro-MMPs are cleaved into active MMPs, which in turn act on various substrates in the ECM and on the cell surface. MMPs play an important role in the regulation of numerous physiological processes including vascular remodeling and angiogenesis. MMPs may also be involved in vascular diseases such as hypertension, atherosclerosis, aortic aneurysm, and varicose veins. MMPs also play a role in the hemodynamic and vascular changes associated with pregnancy and preeclampsia. The role of MMPs is commonly assessed by measuring their gene expression, protein amount, and proteolyic activity using gel zymography. Because there are no specific activators of MMPs, MMP inhibitors are often used to investigate the role of MMPs in different physiologic processes and in the pathogenesis of specific diseases. MMP inhibitors include endogenous tissue inhibitors (TIMPs) and pharmacological inhibitors such as zinc chelators, doxycycline and marimastat. MMP inhibitors have been evaluated as diagnostic and therapeutic tools in cancer, autoimmune and cardiovascular disease. Although several MMP inhibitors have been synthesized and tested both experimentally and clinically, only on MMP inhibitor, i.e. doxycycline, is currently approved by the Food and Drug Administration. This is mainly due to the undesirable side effects of MMP inhibitors especially on the musculoskeletal system. While most experimental and clinical trials of MMP inhibitors have not demonstrated significant benefits, some trials still showed promising results. With the advent of new genetic and pharmacological tools, disease-specific MMP inhibitors with fewer undesirable effects are being developed and could be useful in the management of vascular disease.
TIMP; endothelium; vascular smooth muscle; extracellular matrix; angiogenesis; atherosclerosis; hypertension; aneurysm; varicose veins; pregnancy; preeclampsia
Osteoarthritic chondrocytes secrete matrix metalloproteinase-13 (MMP-13) in response to interleukin-1 (IL-1), causing digestion of type II collagen in cartilage. Using chondrocytic cells, we previously determined that IL-1 induced a strong MMP-13 transcriptional response that requires p38 MAPK, JNK and the transcription factor NF-κB. Now, we have studied the tissue-specific transcriptional regulation of MMP-13. Constitutive expression of the transcription factor Runx-2 correlated with the ability of a cell type to express MMP-13 and was required for IL-1 induction; moreover, Runx-2 enhanced IL-1 induction of MMP-13 transcription by synergizing with the p38 MAPK signaling pathway. Transiently transfected MMP-13 promoters were not IL-1 inducible. However, –405 bp of stably integrated promoter was sufficient for 5- to 6-fold IL-1 induction of reporter activity and this integrated reporter required the same p38 MAPK pathway as the endogenous gene. Finally, mutation of the proximal Runx binding site and the proximal AP-1 site blunted the transcriptional response to IL-1, and double mutation synergistically decreased reporter activity. In summary, our data suggest that the transcriptional MMP-13 response to IL-1 is controlled by the p38 pathway interacting at the MMP-13 promoter through the tissue-specific transcription factor Runx-2 and the ubiquitous AP-1 transcription factor.
Metalloproteinases produced by connective tissue cells may play a key part in the destruction of joints in rheumatoid arthritis. Matrix metalloproteinase 3 (MMP-3; stromelysin) capable of degrading cartilage proteoglycans and type IX collagen and of activating procollagenase was immunolocalised in hyperplastic synovial lining cells in rheumatoid synovium, but not in the cells of normal synovium. Cells responsible for synthesis of MMP-3 have the phenotype of synovioblasts (B cells) by immunoelectron microscopy, but not of phagocytic synovial macrophages (A cells). Cultured monolayer of rheumatoid synovial cells synthesises MMP-3 only under treatment with macrophage conditioned medium. Immunolocalisation of MMP-3 in rheumatoid synovium and cultured synovial cells was possible when the specimens were treated with a monovalent ionophore, monensin. These results suggest that MMP-3 is synthesised and secreted continuously without storage from hyperplastic synovioblasts stimulated by factor(s) derived from activated macrophages present in the synovium.
Objective: To clarify the effect of interleukin (IL) 18 on cartilage degeneration by studying the profile of IL18 receptor (IL18R) on chondrocytes and the direct effect of IL18 on production of matrix metalloproteinases (MMPs), aggrecanases, and tissue inhibitors of metalloproteinases (TIMPs) in articular chondrocytes.
Methods: Monolayer cultured human articular chondrocytes were isolated from non-arthritic subjects and patients with rheumatoid arthritis or osteoarthritis. Gene expression of IL18, IL18Rα, IL18Rß, MMPs, and aggrecanases was detected by RT-PCR. Protein levels of IL18Rα were analysed by flow cytometry. Protein levels of IL18, MMPs, and TIMPs were measured by ELISA. Aggrecanase-2 mRNA expression was quantitatively analysed by real time RT-PCR. Protein levels of signalling molecules were assayed by western blotting.
Results: IL18 mRNA was constitutively expressed in chondrocytes, and was enhanced by IL1ß stimulation. Flow cytometric analysis showed that IL1ß, tumour necrosis factor α, and IL18 up regulated IL18Rα expression levels. The level of IL18Rß mRNA was much lower than that of IL18Rα, and was slightly up regulated by IL1ß. In chondrocytes responding to IL18, IL18 (1–100 ng/ml) slightly increased the production of MMP-1, MMP-3, and MMP-13, which was blocked by NF-κB inhibitor and p38 mitogen activated protein kinase inhibitor. IL18 up regulated mRNA expression of aggrecanase-2, but not aggrecanase-1. IL18 also slightly stimulated TIMP-1 production?through extracellular signal regulated kinase activation.
Conclusion: IL18 induces production of MMPs from chondrocytes in inflammatory arthritis. Although the direct effect of IL18 on chondrocytes may not be pivotal for the induction of cartilage degeneration, IL18 seems to play some part in the degradation of articular cartilage in arthritis.