Modified proenzymes as artificial substrates for proteolytic enzymes: colorimetric assay of bacterial collagenase and matrix metalloproteinase activity using modified pro-urokinase

Biosensors and bioassays for determination of matrix metalloproteinases: state of the art and recent advances

Matrix metalloproteinases (MMPs) are closely associated with various physiological and pathological processes, and have been regarded as potential biomarkers for severe diseases including cancer. Accurate determination of MMPs would advance our understanding of their roles in disease progression, and is of great significance for disease diagnosis, treatment and prognosis. In this review, we present a comprehensive overview of the developed bioassays/biosensors for detection of MMPs, and highlight the recent advancement in nanomaterial-based immunoassays for MMP abundance measurements and nanomaterial-based biosensors for MMP activity determination. Enzyme-linked immunosorbent assay (ELISA)-based immunoassays provide information about total levels of MMPs with high specificity and sensitivity, while target-based biosensors measure the amounts of active MMPs, and allow imaging of MMP activities in vivo. For multiplex and high-throughput analysis of MMPs, microfluidics and microarray-based assays are described. Additionally, we put forward the existing challenges and future prospects from our perspective.

Effects of Pentoxifylline on Peritoneal Fibroblasts and Silica-Induced Peritoneal Fibrosis

♦ Background

Peritoneal fibrosis is a long-term complication following continuous ambulatory peritoneal dialysis (CAPD). Peritoneal fibroblasts may play an important role in peritoneal fibrosis. Up to now, the treatment of peritoneal fibrosis in patients with CAPD remains unsatisfactory. Pentoxifylline (PTX) is a xanthine derivative and is used in the treatment of peripheral vascular and cerebrovascular diseases. Several studies have demonstrated that PTX can ameliorate fibrosis of the skin, liver, and kidney.

♦ Objective

To investigate the effect of PTX on in vitro growth and collagen synthesis of human peritoneal fibroblasts (HPFBs), and to evaluate the effects of PTX on silica-induced peritoneal fibrosis in vivo.

♦ Design and Measurements

In the in vitro study, HPFBs were cultured from human omentum. The effect of PTX on the growth of serum-stimulated HPFBs was evaluated by MTT assay. The effect of PTX on the collagen synthesis of HPFB was measured by [3H]-proline incorporation. Expression of type I and type III collagen mRNA was evaluated by Northern blotting. The effects of PTX on matrix metalloproteinase (MMP) activity and cAMP level in HPFBs were measured by immunoassays. In the in vivo study, Wistar rats were randomly divided into five groups. All rats received intraperitoneal (IP) injection of silica suspension (250 mg/100 g body weight) on day 0. The rats of group 1 (control group) were injected with vehicle IP every day for 14 days. The rats of groups 2, 3, and 4 were injected with PTX (4 mg/100 g body weight) IP every day for 3, 7, and 14 days, respectively. The rats in group 5 received an intravenous infusion of PTX (8 mg/100 g body weight) every day for 7 days. On the 15th day after silica injection, all rats were sacrificed. Their parietal and visceral peritoneums were removed and processed for pathology, and the severity of fibrosis was measured and scored. ♦ Results: In vitro, PTX inhibited serum-stimulated HPFB growth (maximum was 93% at 1 mg PTX/mL) in a dose-dependent manner. Collagen synthesis by HPFB was reduced (47% at 1 mg PTX/mL), and collagen I and III mRNA expression in HPFBs was suppressed by PTX. The PTX did not affect the MMP (including MMP-1, MMP-8, and MMP-13) activities of HPFBs. The mechanism of PTX was through increasing cAMP by its phosphodiesterase inhibiting activity. In vivo, the severity of fibrosis was significantly reduced in groups 4 and 5 compared to group 1 ( p < 0.05).

♦ Conclusion

These results suggest that PTX can inhibit growth of and collagen synthesis by HPFBs in vitro. The fibrosis derived from silica-induced peritonitis in vivo was also ameliorated by PTX. Therefore, pentoxifylline may have the potential to be used to treat peritoneal fibrosis in patients on CAPD.

One-step sensing of foodborne pathogenic bacteria using a 3D paper-based device

Managing food contamination from bacteria has been an ongoing issue in the public health and industrial fields. Enzymatic substrates possessing optical properties, e.g. fluorescence or color manifestation, are widely exploited in pathogenic/non-pathogenic bacteria culture methods. Recently, various chromogenic substrates have been utilized in the development of point-of-care diagnostic tools. Herein, four types of chromogenic substrates were exploited to develop paper-based sensors for major foodborne pathogens. We designed a compact sized three-dimensional paper device with a simple user interface. By inserting functional layers in the middle of multilayers, pre-lysis and pH regulation steps were excluded and the analysis time was subsequently reduced, while only one sample droplet was needed for the whole analysis process. After the enzymatic reactions had proceeded, target-specific colors appeared. When it was combined with enrichment, 101 cfu mL-1 of pathogens were successfully detected in 4-8 hours, while those in milk samples were readily sensed in 12 hours. The proposed bacteria sensor exhibited great advantages of low cost, portability and simple operation, while showing a respectable limit-of-detection as low as 101 cfu mL-1 and below. Significantly, we emphasize that it takes fewer steps than existing methods and provides a reduced analysis time owing to the layer functionalization.

Myosin-IIA heavy chain phosphorylation on S1943 regulates tumor metastasis

Nonmuscle myosin-IIA (NMHC-IIA) heavy chain phosphorylation has gained recognition as an important feature of myosin-II regulation. In previous work, we showed that phosphorylation on S1943 promotes myosin-IIA filament disassembly in vitro and enhances EGF-stimulated lamellipod extension of breast tumor cells. However, the contribution of NMHC-IIA S1943 phosphorylation to the modulation of invasive cellular behavior and metastasis has not been examined. Stable expression of phosphomimetic (S1943E) or non-phosphorylatable (S1943A) NMHC-IIA in breast cancer cells revealed that S1943 phosphorylation enhances invadopodia function, and is critical for matrix degradation in vitro and experimental metastasis in vivo. These studies demonstrate a novel link between NMHC-IIA S1943 phosphorylation, the regulation of extracellular matrix degradation and tumor cell invasion and metastasis.

Activatable T1 Relaxivity Recovery Nanoconjugates for Kinetic and Sensitive Analysis of Matrix Metalloprotease 2

Sensitive detection of matrix metalloproteinase 2 (MMP-2, an important cancer marker associated with tumor invasion and metastasis) activity in vitro and at cellular level is of great significance to clinical diagnosis and medical treatment. With unique physical properties, nanoparticles are emerging as a platform for the construction of conjugates of various biological molecules, which can be expected to generate new types of biosensors. In this work, Fe₃O₄ NPs were modified with Gd chelates via linking peptides to construct NP-substrate (Fe₃O₄-pep-Gd) conjugates for kinetic MMP-2 activity assessment in vitro at the cellular level and in vivo. Superparamagnetic Fe₃O₄ quenched the longitudinal relaxation effect (T₁ relaxivity) of the attached Gd chelates by perturbing proton relaxation process under an external magnetic field. MMP-2 cleaved the peptide substrates and released Gd chelates from the local magnetic fields accompanied by T₁ relaxivity recovery and T₁ contrast enhancement. Benefiting from signal amplification through binding multiple Gd chelates to one linking peptide, Fe₃O₄-pep-Gd conjugates exhibited high sensitivity for the detection of MMP-2 (as low as 0.5 nM). Enzymatic processes were in good agreement with the integrated Michaelis-Menten model, revealing an unexpected activity enhancement in the initial stage. Fe₃O₄-pep-Gd conjugates could also probe MMP-2 at cellular level and in vivo that indicates a great promise in in vitro diagnosis (IVD) and disease monitoring.

Effect of Nd:YAG laser-assisted non-surgical periodontal therapy on clinical periodontal and serum biomarkers in patients with and without coronary artery disease: A short-term pilot study

BACKGROUND/OBJECTIVE

We hypothesized that nonsurgical-periodontal-therapy (NSPT) with adjunct Nd:YAG laser therapy is more effective in reducing periodontal inflammatory parameters (plaque index [PI], bleeding-on-probing [BOP], and probing-pocket-depth [PPD]) and serum interleukin-1beta (IL-1β) and matrix metalloproteinase-9 (MMP-9) levels in patients with and without coronary artery disease (CAD) than NSPT alone. The aim of this short-term pilot study was to assess the effect of NSPT + Nd:YAG laser therapy on periodontal parameters and serum IL-1β and MMP-9 levels in patients with and without CAD.

STUDY DESIGN

A prospective randomized clinical study was conducted on 87 patients who were divided into two groups: Group-1: 44 patients with CAD and periodontal disease (PD) and Group-2: 43 patients with PD alone. Treatment-wise, these individuals were randomly divided into two subgroups: (i) NSPT alone and (ii) NSPT + Nd:YAG laser therapy. Demographic information was collected using a self-completed questionnaire. Periodontal parameters (PI, BOP, and PPD) and serum IL-1β and MMP-9 levels were measured at baseline and after 3 months of treatment. P-values <0.05 were considered statistically significant.

RESULTS

At 3 months follow-up, PI (P < 0.01), BOP (P < 0.01), PPD ≥ 4 mm (P < 0.01), and serum IL-1β (P < 0.01) and MMP-9 (P < 0.01) levels were significantly higher in patients treated with NSPT alone than those treated with NSPT + Nd:YAG laser therapy. Among patients that underwent NSPT + laser therapy in both groups, periodontal parameters and serum IL-1β, and MMP-9 levels were comparable at 3-months follow-up.

CONCLUSION

NSPT + Nd:YAG laser therapy may be more effective in reducing periodontal inflammation and serum IL-1β and MMP-9 levels in patients with and without CAD than NSPT alone. Lasers Surg. Med. 48:929-935, 2016. © 2016 Wiley Periodicals, Inc.

Effects of the immunosuppressant rapamycin on the expression of human α2(I) collagen and matrix metalloproteinase 1 genes in scleroderma dermal fibroblasts

BACKGROUND

Rapamycin has been shown to exert an anti-fibrotic effect on skin fibrosis in a certain subset of patients with systemic sclerosis (SSc) and in bleomycin-treated animal models.

OBJECTIVES

To investigate the mechanism responsible for the anti-fibrotic effect of rapamycin especially by focusing on human α2(I) collagen (COL1A2) and matrix metalloproteinase 1 (MMP1) genes in normal and systemic sclerosis (SSc) dermal fibroblasts.

METHODS

The expression levels of type I procollagen and MMP1 proteins were analyzed by immunoblotting and the mRNA levels of COL1A2 and MMP1 genes were evaluated by quantitative real-time RT-PCR. The activities of COL1A2 and MMP1 promoters were determined by reporter analysis.

RESULTS

Rapamycin significantly decreased the levels of type I procollagen protein and COL1A2 mRNA, while significantly increasing the levels of MMP1 protein and mRNA in normal dermal fibroblasts. Similar effects of rapamycin were also observed in SSc dermal fibroblasts. Importantly, the inhibitory and stimulatory effects of rapamycin on the mRNA levels of COL1A2 and MMP1 genes, respectively, were significantly greater in SSc dermal fibroblasts than in normal dermal fibroblasts. In SSc dermal fibroblasts, rapamycin affected the expression of COL1A2 gene at the post-transcriptional level. In contrast, rapamycin altered the expression of MMP1 gene at the transcriptional level through the JNK/c-Jun signaling pathway in those cells.

CONCLUSION

Rapamycin has a potential to directly regulate the deposition of type I collagen in extracellular matrix through inhibiting type I collagen synthesis and promoting its degradation by MMP1, suggesting that this drug is useful for the treatment of SSc.

Fluorometric immunocapture assay for the specific measurement of matrix metalloproteinase-9 activity in biological samples: application to brain and plasma from rats with ischemic stroke

BACKGROUND

Matrix metalloproteinases are important factors in the molecular mechanisms leading to neuronal injury in many neurological disorders. Matrix metalloproteinase (MMP)-9 is up-regulated after cerebral ischemia and neuroinflammation and is actively involved in blood-brain barrier disruption. Current methods of measuring MMP-9 activity, such as gelatin-substrate zymography, are unspecific and arduous. Here we developed an immunocapture assay with high efficiency, specificity, and sensitivity for quantifying endogenously active as well as total MMP-9 activity.

RESULTS

A fluorescence resonance energy transfer (FRET) peptide-based immunocapture assay was developed that enables the accurate assessment of total and active forms of MMP-9 in complex biological samples. The FRET assay demonstrated correct and efficient binding of MMP-9 to a mouse monoclonal MMP-9 antibody and high specificity of the immunocapture antibody for MMP-9. Total and active levels of MMP-9 were measured in rat brain homogenates, plasma, human HT-1080 conditioned media, and RBE4 endothelial cell lysates. The FRET immunocapture assay yielded highly similar results for total MMP-9 activity when compared to gelatin-substrate zymography.

CONCLUSIONS

We suggest that the new FRET peptide-based immunocapture assay is a viable replacement of zymography for sensitive and high throughput quantification of MMP-9 activity in biological samples.

Recent development of highly sensitive protease assay methods: Signal amplification through enzyme cascades

Proteases are involved in almost all biological processes, and therefore, aberrant activity of many of these enzymes is an important indicator of disease. Various methods have been developed to analyze protease activity, among which, protease assays based on resonance energy transfer are currently used most widely. However, quantitative methods with relatively higher sensitivity are needed, especially for disease diagnosis at early stages. One of the strategies to achieve higher sensitivity is to implement signal amplification of the protease activity. In this review, we briefly summarize the protease assay methods based on resonance energy transfer, and then elaborate the efforts to develop sensitive protease assays through signal amplification by using enzyme cascades.

Analytic study of three-dimensional single cell migration with and without proteolytic enzymes

Cell motility is a fundamental physiological process that regulates cellular fate in healthy and diseased systems. Cells cultured in 3D environments often exhibit biphasic dependence of migration speed with cell adhesion. Much is not understood about this very common behavior. A phenomenological model for 3D single-cell migration that exhibits biphasic behavior and highlights the important role of steric hindrance is developed and studied analytically. Changes in the biphasic behavior in the presence of proteolytic enzymes are investigated. Our methods produce a framework to determine analytic formulae for the mean cell speed, allowing general statements in terms of parameters to be explored, which will be useful when interpreting future experimental results. Our formula for mean cell speed as a function of ligand concentration generalizes and extends previous computational models that have shown good agreement with in vitro experiments.

Matrix metalloproteinases and their clinical relevance in urinary bladder cancer

Matrix metalloproteinases (MMPs) have important roles in several cancer-supporting cellular processes, such as extracellular matrix (ECM) remodeling, angiogenesis, apoptosis, epithelial-to-mesenchymal transition and cell proliferation. This broad range of activity has led to considerable interest in the use of MMPs in the clinical setting as diagnostic or prognostic biomarkers and as therapeutic targets. Levels of the different MMPs can be measured in several sample types, including paraffin-embedded or fresh frozen tissue, serum, plasma and urine, and by various analytical methodologies, such as immunohistochemistry, real-time PCR, western and northern blot analyses, enzyme-linked immunosorbent assay and zymography. Several MMPs have been identified as having potential diagnostic or prognostic utility, whether alone or in combination with currently available diagnostic tests or imaging modalities. Although the early broad-spectrum anti-MMP agents showed a lack of efficacy, our continually improving understanding of the complex physiologic and pathologic roles of MMPs might enable the development of new MMP-specific and tumor-specific therapies. Accordingly, MMPs will continue to be the subjects of intensive research in bladder cancer.

Matrix metalloproteinase-9 measured in urine from bladder cancer patients is an independent prognostic marker of poor survival

INTRODUCTION

Matrix metalloproteinase 9 (MMP-9) is an endopeptidase involved in various cellular processes, such as tumour development and metastatic spread. In biological samples, MMP-9 can occur as pro-MMP-9 and active MMP-9, or these factors complexed with the inhibitor TIMP-1. An assay, which can measure active and total MMP-9 in biological samples, has been used on the urine from bladder cancer patients and demonstrated a significant correlation between MMP-9 and clinical parameters. The prognostic value of these measurements has never been investigated. Using this assay we have investigated the prognostic influence of total and active MMP-9 in urine from bladder cancer patients.

MATERIAL AND METHODS

Fresh voided urines from 188 consecutive patients diagnosed with bladder cancer were collected and frozen at diagnosis. After 15 years follow-up 13 patients were still alive, and 175 patients had died. MMP-9 was measured with an immunocapture activity assay.

RESULTS

Median MMP-9(total) was 173.7 units/10 g creatinine (range 0-34 792), and median MMP-9(active) was 14 units/10g creatinine (range, 0-294 757). The two factors were correlated (Spearman´s rho 0.74, p<0.0001). High MMP-9(total) and MMP-9(active) were significantly correlated with large tumour size and poor malignancy grade. Increasing tertiles of MMP-9(total) and MMP-9(active) were associated with poor overall survival (p<0.0001 and p=0.003, respectively). A Cox multivariate analysis using death as endpoint identified high tertiles of MMP-9(total) as independent prognostic markers with a relative risk 2.25 (95% confidence interval, 1.53-3.30).

CONCLUSION

MMP-9 measured in urine from bladder cancer patients was a strong independent prognostic marker of poor survival. This is the first time high levels of MMP-9 measured in urine from bladder cancer patients have been linked to poor prognosis. This may reflect MMP-9 playing a role in tumour invasion and metastasis. It may be possible to non-invasively measure tumour response to therapy and identify possible tumour recurrence in an early phase.

Correlation between the matrix metalloproteinase-9 activity and chondroitin sulfate concentrations in tear fluid after laser in situ keratomileusis

Aims:

The aim of the present study was to evaluate the correlation between matrix metalloproteinase-9 (MMP-9) and chondroitin sulfate (CS) concentrations in human tear fluid following laser in situ keratomileusis (LASIK).

Methods:

Twelve eyes from six patients who had no ocular complaints except for refractive errors, and who had undergone LASIK, were enrolled in this study. We measured the concentrations of chondroitin 4 sulfate (C4S), chondroitin 6 sulfate (C6S), and MMP-9 activity with an enzyme-linked immunosorbent assay and an enzyme immunocapture activity assay preoperatively and postoperatively on days 1 and 4, week 1, and at 1 and 3 months.

Results:

Although the preoperative MMP-9 activity and the C4S concentration were highly correlated (r = 0.900; P < 0.001), they were not postoperatively correlated at month 1. Although the preoperative MMP-9 activity and the C6S concentration were highly correlated (r = 0.885; P < 0.001), they were not postoperatively correlated at either week 1 or months 1 and 3.

Conclusions:

The correlation appeared to be collapsed by LASIK, and it did not recover to the preoperative score at 3 months post-surgery. Our study indicates that the corneal wound healing was not terminated at 3 months following LASIK.

A novel urokinase receptor-targeted inhibitor for plasmin and matrix metalloproteinases suppresses vein graft disease

AIMS

Matrix metalloproteinases (MMP) and plasminogen activator (PA)/plasmin-mediated proteolysis, especially at the cell surface, play important roles in matrix degeneration and smooth muscle cell migration, which largely contributes to vein graft failure. In this study, a novel hybrid protein was designed to inhibit both protease systems simultaneously. MMP and plasmin activity were inhibited at the cell surface by this hybrid protein, consisting of the receptor-binding amino-terminal fragment (ATF) of urokinase-type PA, linked to both the tissue inhibitor of metalloproteinases (TIMP-1) and bovine pancreas trypsin inhibitor (BPTI), a potent protease inhibitor. The effect of overexpression of this protein on vein graft disease was studied.

METHODS AND RESULTS

A non-viral expression vector encoding the hybrid protein TIMP-1.ATF.BPTI was constructed and validated. Next, cultured segments of human veins were transfected with this vector. Expressing TIMP-1.ATF.BPTI in vein segments resulted in a mean 36 ± 14% reduction in neointima formation after 4 weeks. In vivo inhibition of vein graft disease by TIMP-1.ATF.BPTI is demonstrated in venous interpositions placed into carotid arteries of hypercholesterolaemic APOE*3Leiden mice. After 4 weeks, vein graft thickening was significantly inhibited in mice treated with the domains TIMP-1, ATF, or BPTI (36-49% reduction). In the TIMP-1.ATF.BPTI-treated mice, vein graft thickening was reduced by 67±4%, which was also significantly stronger when compared with the individual components.

CONCLUSION

These data provide evidence that cell surface-bound inhibition of the PA and MMP system by the hybrid protein TIMP-1.ATF.BPTI, overexpressed in distant tissues after electroporation-mediated non-viral gene transfer, is a powerful approach to prevent vein graft disease.

Computational study of proteolysis-driven single cell migration in a three-dimensional matrix

Cell migration is a fundamental process that is crucial to a variety of physiological events. While traditional approaches have focused on two-dimensional (2D) systems, recent efforts have shifted to studying migration in three-dimensional (3D) matrices. A major distinction that has emerged is the increased importance of cell-matrix interactions in 3D environments. In particular, cell motility in 3D matrices is more dependent on matrix metalloproteinases (MMPs) to degrade steric obstacles than in 2D systems. In this study, we implement the effects of MMP-mediated proteolysis in a force-based computational model of 3D migration, testing two matrix ligand-MMP relationships that have been observed experimentally: linear and log-linear. The model for both scenarios predicts maximal motility at intermediate matrix ligand and MMP levels, with the linear case providing more physiologically compelling results. Recent experimental results suggesting MMP influence on integrin expression are also integrated into the model. While the biphasic behavior is retained, with MMP-integrin feedback peak cell speed is observed in a low ligand, high MMP regime instead of at intermediate ligand and MMP levels for both ligand-MMP relationships. The simulation provides insight into the expanding role of cell-matrix interactions in cell migration in 3D environments and has implications for cancer research.

Local cytokine profiles in knee osteoarthritis: elevated synovial fluid interleukin-15 differentiates early from end-stage disease

OBJECTIVE

Much of what is known about the inflammatory response in the synovial membrane (SM) of patients with osteoarthritis (OA) comes from studies of synovial tissues from end-stage disease. In this study, we sought to better characterize the inflammatory infiltrate in symptomatic patients with early signs of knee OA, and to determine how inflammatory cell populations relate to the pattern of cytokine and degradative enzyme production.

METHODS

Study populations comprised patients with degenerative meniscal tears and early cartilage thinning undergoing arthroscopic procedures (early OA) and patients undergoing total knee replacement for end-stage OA. Quantitative real-time polymerase chain reaction (PCR) was used to measure expression of SM cytokines and enzymes implicated in the pathogenesis of inflammatory arthritis and OA, as well as cell lineage-specific markers. We quantified synovial fluid (SF) cytokines and enzymes by enzyme-linked immunosorbent assay (ELISA) and SM cell populations by immunohistochemistry.

RESULTS

We found increased levels of SF interleukin-15 (IL-15) protein in the early knee OA patients when compared to end-stage OA. Both SF IL-15 protein and numbers of CD8 cells within SM correlated with matrix metalloproteinase-1 (MMP-1) and three levels. TNF-alpha, IL-6 and IL-21 were also detectable in the SF of the majority of patients, and IL-15 levels were associated with IL-6 levels.

CONCLUSION

IL-15 is elevated in early knee OA, suggesting activation of an innate immune response in the SM. The association of IL-15 expression with CD8 transcripts and MMPs implicates this cytokine in OA pathogenesis and as a candidate therapeutic target.

Functional proteomics on zinc-dependent metalloproteinases using inhibitor probes

Metzincins are a family of zinc(II)-dependent metalloproteinases with well known members such as the matrix metalloproteinases (MMPs) and A disintegrin and metalloproteinases (ADAMs). Metzincins are largely responsible for the modulation and regulation of the extracellular matrix by proteolytic degradation of extracellular matrix (ECM) proteins, and by liberation or production of biologically active proteins from their pro-forms. Since metzincin activity is strictly regulated in vivo, novel analysis methods are necessary to elucidate the role of the active enzymes in health and disease. This concept gives an overview of available methods, and describes an approach to use synthetic metzincin inhibitors as affinity probes for selective determination of active metzincins in biological and clinical samples.

Adiponectin protects against cerebral ischemia-reperfusion injury through anti-inflammatory action

Adiponectin (APN), a circulating adipose-derived hormone regulating inflammation and energy metabolism, has beneficial actions on cardio- and cerebrovascular disorders. Hypoadiponectinemia is associated with ischemic cerebrovascular disease, however, little is known about the cerebroprotective action of APN as well as its molecular mechanisms. In the present study, the role of APN in the pathogenesis of acute cerebral injury was investigated. Rats were divided into three groups: (i) a sham operation group; (ii) an ischemia/reperfusion (I/R) group, rats were subjected to 1 h middle cerebral artery occlusion followed by 23 h reperfusion (I/R); (iii) a APN-treated group, two bolus of 5 microg APN was administered through jugular vein before and after operation. I/R resulted in obvious cerebral infarct size, neurological deficits, and increased expression of endogenous immunoglobin G and matrix metalloproteinase 9, which can be significantly diminished by administration of APN. We also found that APN can significantly inhibited cerebral expression of myeloperoxidase, a distinct indicator of inflammatory cell infiltration, and inflammatory cytokines, interleukin (IL)-1beta, tumor necrosis factor-alpha and IL-8 in response to I/R, suggesting that APN exerts potent anti-inflammatory actions. Furthermore, nuclear factor (NF)-kappaB (p65), a critical transcription factor involved in inflammatory reactions, was observed predominantly located in the nucleus after I/R, whereas APN can obviously inhibit its translocation from cytoplasm into the nucleus. Results of this study demonstrate that APN exerts a potent cerebroprotective function through its anti-inflammatory action, and NF-kappaB (p65) is a key component in this process. APN might be potential molecular targets for ischemic stroke therapy.

1alpha,25-dihydroxyvitamin D3 inhibits matrix metalloproteinases induced by Mycobacterium tuberculosis infection

Matrix metalloproteinases (MMP) can degrade all components of pulmonary extracellular matrix. Mycobacterium tuberculosis induces production of a number of these enzymes by human macrophages, and these are implicated in the pathogenesis of pulmonary cavitation in tuberculosis. The active metabolite of vitamin D, 1alpha,25-dihydroxyvitamin D(3) [1alpha,25(OH)(2)D(3)], has previously been reported to inhibit secretion of MMP-9 in human monocytes (MN), but its influence on the secretion and gene expression of MMP and tissue inhibitors of MMP (TIMP) in M. tuberculosis-infected cells has not previously been investigated. We therefore determined the effects of 1alpha,25(OH)(2)D(3) on expression, secretion and activity of a number of MMP and TIMP in M. tuberculosis-infected human leucocytes; we also investigated the effect of 1alpha,25(OH)(2)D(3) on the secretion of interleukin-10 (IL-10) and prostaglandin E(2) (PGE(2)), both transcriptional regulators of MMP expression. We found that M. tuberculosis induced expression of MMP-1, MMP-7 and MMP-10 in MN and MMP-1 and MMP-10 in peripheral blood mononuclear cells (PBMC). 1alpha,25(OH)(2)D(3) significantly attenuated M. tuberculosis-induced increases in expression of MMP-7 and MMP-10, and suppressed secretion of MMP-7 by M. tuberculosis-infected PBMC. MMP-9 gene expression, secretion and activity were significantly inhibited by 1alpha,25(OH)(2)D(3) irrespective of infection. In contrast, the effects of 1alpha,25(OH)(2)D(3) on the expression of TIMP-1, TIMP-2 and TIMP-3 and secretion of TIMP-1 and TIMP-2 were small and variable. 1alpha,25(OH)(2)D(3) also induced secretion of IL-10 and PGE(2) from M. tuberculosis-infected PBMC. These findings represent a novel immunomodulatory role for 1alpha,25(OH)(2)D(3) in M. tuberculosis infection.

Advances in assays of matrix metalloproteinases (MMPs) and their inhibitors

Matrix metalloproteinases (MMPs) play an important role in many physiological and pathological processes. To assay the activities of MMPs is important in diagnosis and therapy of the MMPs associated diseases, such as neoplastic, rheumatic and cardiovascular diseases. Several assay systems have been developed, which include bioassay, zymography assay, immunoassay, fluorimetric assay, radio isotopic assay, phage-displayed assay, multiple-enzyme/multiple-reagent assay and activity-based profiling assay. The principle, application, advantage and disadvantage of these assays have been reviewed in this article.

Effects of anticoagulants on the activity of gelatinases

OBJECTIVES

To identify the best procedure for preanalytical blood collection in the determination of matrix metalloproteinase (MMP)-2 and -9 by testing the effects of anticoagulants on their activity.

DESIGN AND METHODS

Active forms of both gelatinases were measured by specific activity assay systems in serum, plasma EDTA, plasma-heparin and plasma-citrate obtained from 20 healthy volunteers, as well as in a pooled serum sample before and after anticoagulant treatment.

RESULTS

: Active MMP-2 and MMP-9 mean concentrations were similar in serum and in plasma-citrate, higher in plasma EDTA than in serum, in plasma-heparin and in plasma-citrate, and lower in plasma-heparin than in serum and plasma-citrate. A similar trend was observed in untreated and treated pooled serum samples.

CONCLUSIONS

Our results indicate that MMP-2 and MMP-9 in their active forms are not released by platelets during blood clotting, whereas the use of calcium chelating anticoagulants can profoundly alter the activity of endogenous gelatinases. This suggests that the determination of active forms of MMP-2 and MMP-9 in serum samples represents a suitable procedure.

Efferent vagal nerve stimulation induces tissue inhibitor of metalloproteinase-1 in myocardial ischemia-reperfusion injury in rabbit

Vagal nerve stimulation has been suggested to ameliorate left ventricular (LV) remodeling in heart failure. However, it is not known whether and to what degree vagal nerve stimulation affects matrix metalloproteinase (MMP) and tissue inhibitor of MMP (TIMP) in myocardium, which are known to play crucial roles in LV remodeling. We therefore investigated the effects of electrical stimulation of efferent vagal nerve on myocardial expression and activation of MMPs and TIMPs in a rabbit model of myocardial ischemia-reperfusion (I/R) injury. Anesthetized rabbits were subjected to 60 min of left coronary artery occlusion and 180 min of reperfusion with (I/R-VS, n = 8) or without vagal nerve stimulation (I/R, n = 7). Rabbits not subjected to coronary occlusion with (VS, n = 7) or without vagal stimulation (sham, n = 7) were used as controls. Total MMP-9 protein increased significantly after left coronary artery occlusion in I/R-VS and I/R to a similar degree compared with VS and sham values. Endogenous active MMP-9 protein level was significantly lower in I/R-VS compared with I/R. TIMP-1 mRNA expression was significantly increased in I/R-VS compared with the I/R, VS, and sham groups. TIMP-1 protein was significantly increased in I/R-VS and VS compared with the I/R and sham groups. Cardiac microdialysis technique demonstrated that topical perfusion of acetylcholine increased dialysate TIMP-1 protein level, which was suppressed by coperfusion of atropine. Immunohistochemistry demonstrated a strong expression of TIMP-1 protein in cardiomyocytes around the dialysis probe used to perfuse acetylcholine. In conclusion, in a rabbit model of myocardial I/R injury, vagal nerve stimulation induced TIMP-1 expression in cardiomyocytes and reduced active MMP-9.

Collagen degradation in the abdominal aneurysm: a conspiracy of matrix metalloproteinase and cysteine collagenases

Growth and rupture of abdominal aortic aneurysms (AAAs) result from increased collagen turnover. Collagen turnover critically depends on specific collagenases that cleave the triple helical region of fibrillar collagen. As yet, the collagenases responsible for collagen degradation in AAAs have not been identified. Increased type I collagen degradation products confirmed collagen turnover in AAAs (median values: <1, 43, and 108 ng/mg protein in control, growing, and ruptured AAAs, respectively). mRNA and protein analysis identified neutrophil collagenase [matrix metalloproteinase (MMP)-8] and cysteine collagenases cathepsin K, L, and S as the principle collagenases in growing and ruptured AAAs. Except for modestly increased MMP-14 mRNA levels, collagenase expression was similar in growing and ruptured AAAs (anterior-lateral wall). Evaluation of posttranslational regulation of protease activity showed a threefold increase in MMP-8, a fivefold increase in cathepsins K and L, and a 30-fold increase in cathepsin S activation in growing and ruptured AAAs. The presence of the osteoclastic proton pump indicated optimal conditions for extracellular cysteine protease activity. Protease inhibitor mRNA expression was similar in AAAs and controls, but AAA protein levels of cystatin C, the principle cysteine protease inhibitor, were profoundly reduced (>80%). We found indications that this secondary deficiency relates to cystatin C degradation by (neutrophil-derived) proteases.

Effect of the anti-tumor necrosis factor-alpha antibody infliximab on the ex vivo mucosal matrix metalloproteinase-proteolytic phenotype in inflammatory bowel disease

BACKGROUND

Previous studies have shown an upregulation of matrix metalloproteinases (MMPs) in intestinal tissue of patients with inflammatory bowel disease (IBD) and significant clinical improvement after administration of the anti-TNF-a antibody infliximab. The aims of our study were to determine expression and secretion of MMP-1, -2, -3, -9, and their inhibitors TIMP-1, -2 by IBD versus control intestinal mucosa ex vivo and to assess the regulatory capacity by infliximab of the proteolytic phenotype.

METHODS

Intestinal mucosal explants from 20 IBD and 15 control patients were cultured with or without infliximab and/or the T-cell activator pokeweed mitogen (PWM). Explants and culture supernatants were analyzed for MMPs, TIMPs, and TNF-alpha protein, activity and/or mRNA levels. All patients were genotyped for functional TNF-alpha, MMP, and TIMP single nucleotide polymorphism (SNP) loci.

RESULTS

Expression of MMP and TIMP protein/activity in basal medium was higher in IBD versus control explants. Dependent on genotype at SNP loci, infliximab downregulated MMP-1, -3, and -9 relative to TIMP-1 and -2 and also decreased MMP-1 and -3 activities, while PWM enhanced these levels, partly counteracted again by infliximab. The expression of MMP-2 relative to TIMP did not change by treatment with infliximab and/or PWM.

CONCLUSIONS

The high expression of MMPs in patients with IBD suggests a role for these proteinases in the pathogenesis of this disease. Infliximab seems to induce a genotype-associated matrix protective phenotype, which may contribute to the observed therapeutic efficacy of this drug in IBD, particularly at the mucosal surface.

Urokinase-type plasminogen activator gene therapy in liver cirrhosis is mediated by collagens gene expression down-regulation and up-regulation of MMPs, HGF and VEGF

Human urokinase-type plasminogen activator (uPA) gene administration via an adenoviral (Ad)-vector induced cirrhosis regression and ameliorated hepatic dysfunction in a model of experimental liver cirrhosis. The administration of a single dose of 6 x 10(11) viral particles per kilogram of a clinical-grade Ad-vector was evaluated after the onset of rat liver cirrhosis via degradation of deposited collagen and a substantial decrease of alpha-sma-positive cells. Also, gene expression for pro-fibrogenic molecules (Col I, III, IV, TIMP-1 and PAI-1) was clearly down-regulated. In contrast, gene expression for collagen-degrading enzymes such as MMP-13 and MMP-2 was up-regulated. These events correlated with increased amounts of proteic free-TIMP-1, i.e. non-complexed with metalloproteinases (MMPs), indicating the presence of higher amounts of active MMPs inside the liver of cirrhotic animals treated with Ad-huPA. The harmonized and concerted expression of HGF and c-met resulted in exacerbated hepatocyte proliferation, although these events did not induce an abnormal liver growth. Angiogenesis, i.e. formation of new blood vessels, was evaluated by vascular endothelial growth factor (VEGF) expression which was notably detected to be 10 times higher during the first 6 days after Ad-huPA-treatment in cirrhotic animals as compared with controls. These events provide a clearer rationale as to how Ad-huPA-induced liver regeneration on CCl(4)-induced liver fibrosis takes place.

Infiltration of inflammatory cells plays an important role in matrix metalloproteinase expression and activation in the heart during sepsis

Septicemia is an emerging pathological condition involving, among other effects, refractory hypotension and heart dysfunction. Here we have investigated the contribution of resident nonmyocytic cells to heart alterations after lipopolysaccharide administration. These cells contributed to the rapid infiltration of additional inflammatory cells that enhance the onset of heart disease through the release of inflammatory mediators. Early activation of resident monocytic cells played a relevant role on the infiltration process, mainly of major histocompatibility complex class II- and CD11b-positive cells. This infiltration was significantly impaired in animals lacking the nitric-oxide synthase-2 (NOS-2) gene or after pharmacological in-hibition of NOS-2 or cylooxygenase-2, suggesting a significant contribution of nitric oxide and prostanoids to the infiltration process. Under these conditions, the expression of NOS-2 and cylooxygenase-2 in the whole organ was attenuated because cardiomyocytes failed to express these enzymes. However, cardiomyocytes expressed and activated matrix metalloproteinase-9 through mechanisms regulated, at least in part, by nitric oxide and prostaglandins in an additive way. These results directly link the inflammatory response in the heart and extracellular matrix remodeling by the matrix metalloproteinases released by the cardiomyocytes, suggesting that activation and recruitment of inflammatory cells to the heart is a major early event in cardiac dysfunction promoted by septicemia.

Circulating MMP2 and MMP9 in breast cancer -- potential role in classification of patients into low risk, high risk, benign disease and breast cancer categories

Matrix metalloproteinase (MMP) 2 and 9 are involved in cancer invasion and metastasis, and increased levels occur in serum and plasma of breast cancer (BC) patients. It is, however, unclear whether changes in serum levels can be exploited for early detection or classification of patients into different risk/disease categories. In our study, we measured concentration and activity of MMP2/9 in sera of 345 donors classified as low risk (Gail score <1.7), high risk (HR) (Gail score > or =1.7), benign disease or BC. Kruskal-Wallis and Mann-Whitney nonparametric tests showed that total-MMP2 concentration is higher in HR compared to control (p = 0.012), benign (p = 0.001) and cancer (p = 0.007). Active MMP2 (aMMP2) concentration is higher in control than benign and cancer (p < 0.001, respectively). Total and aMMP9 concentrations are higher in cancer than benign (p < 0.001, p = 0.002, respectively). Total-MMP2 and total-MMP9 activities are lower in control than benign (p < 0.001, p = 0.002, respectively) and cancer (p < 0.001, respectively). Total-MMP2 and MMP9 activities are also higher in cancer than benign (p = 0.004, p < 0.001) and HR (p = 0.008, p = 0.007, respectively). These results were not affected by age or inclusion/exclusion of donors with noninvasive cancer or atypical hyperplasia. Linear discriminant analysis revealed that HR donors are characterized by lower total-MMP2 and higher aMMP2. Overall group classification accuracy was 64.5%. Independent validation based on the leave-one-out cross validation approach gave an overall classification of 63%. Our study provides evidence supporting the potential role of serum MMP2/9 as biomarkers for breast disease classification.

Role of Focal Adhesion Kinase and Phosphatidylinositol 3′-Kinase in Integrin Fibronectin Receptor-Mediated, Matrix Metalloproteinase-1–Dependent Invasion by Metastatic Prostate Cancer Cells

alpha(5)beta(1) Integrin interacts with the PHSRN sequence of plasma fibronectin, causing constitutive invasion by human prostate cancer cells. Inhibition of this process reduces tumorigenesis and prevents metastasis and recurrence. In this study, naturally serum-free basement membranes were used as in vitro invasion substrates. Immunoassays were employed to dissect the roles of focal adhesion kinase (FAK), phosphatidylinositol 3'-kinase (PI3K), and protein kinase Cdelta (PKC delta) in alpha(5)beta(1)-mediated, matrix metalloproteinase-1 (MMP-1)-dependent invasion by metastatic human DU 145 prostate cancer cells. We found that a peptide composed of the PHSRN sequence induced rapid FAK phosphorylation at Tyr(397) (Y397), a site whose phosphorylation is associated with kinase activation. The technique of RNA silencing [small interfering RNA (siRNA)] confirmed the role of FAK in PHSRN-induced invasion. PHSRN also induced the association of the p85-regulatory subunit of PI3K with FAK at a time corresponding to FAK phosphorylation and activation, and maximal PI3K activity occurred at this same time. The necessity of PI3K activity in both PHSRN-induced invasion and MMP-1 expression was confirmed by using specific PI3K inhibitors. By employing a specific inhibitor, Rottlerin, and by using siRNA, we also found that PKC delta, a PI3K substrate found in focal adhesions, functions in PHSRN-induced invasion. In addition, the induction of MMP-1 in PHSRN-treated DU 145 cells was shown by immunoblotting, and the role of MMP-1 in PHSRN-induced invasion was confirmed by the use of blocking anti-MMP-1 monoclonal antibody. Finally, a close temporal correspondence was observed between PHSRN-induced invasion and PHSRN-induced MMP-1 activity in DU 145 cells.

Statin Treatment Is Not Associated With Consistent Alterations in Inflammatory Status of Carotid Atherosclerotic Plaques

BACKGROUND AND PURPOSE

Anti-inflammatory qualities are held partially responsible for the reduction of cardiovascular events after statin treatment. We examined the phenotype of carotid atherosclerotic plaques harvested during carotid endarterectomy in relation to the previous use of different statins prescribed in clinical practice.

METHODS

Three hundred and seventy-eight patients were included. Atherosclerotic plaques were harvested, immunohistochemically stained and semiquantitively examined for the presence of macrophages (CD68), smooth muscle cells, collagen and fat. Adjacent atherosclerotic plaques were used to study protease activity and interleukin levels. Patients' demographics were recorded and blood samples were stored.

RESULTS

Serum cholesterol, low-density lipoprotein, apolipoprotein B, and C-reactive protein levels were lower in patients treated with statins compared with patients without statin treatment. Atheromatous plaques were less prevalent in patients receiving statins compared with patients without statin therapy (29% versus 42%, P=0.04). An increase of CD68 positive cells was observed in patients receiving statins compared with nonstatin treatment (P=0.05). This effect was specifically related to atorvastatin treatment. In patients treated with atorvastatin, the increased amount of CD68 positive cells were not associated with increased protease activity. In contrast, a dose-dependent decrease in protease activity was shown in the atorvastatin group. Interleukin 6 expression was lower in plaques obtained from patients treated with statins (P=0.04).

CONCLUSIONS

Statin use may exert pleiotropic effects on plaque phenotype. However, not the presence of macrophages but activation with subsequent protease and cytokine release may be attenuated by statin use.

Detection of a soluble form of BACE-1 in human cerebrospinal fluid by a sensitive activity assay

BACKGROUND

Formation of deposits of the insoluble amyloid beta-peptide is believed to be causally related with neurodegeneration in Alzheimer disease (AD). The beta-peptide originates from a larger amyloid precursor protein (APP) by the action of proteolytic enzymes. The first proteolytic event leading to amyloid formation is the cleavage of APP by the membrane-bound aspartyl protease BACE-1, also known as memapsin-2. Inhibition of BACE-1 is thought to be a therapeutic approach to AD. Measuring BACE-1 activity in biological samples would be useful to elucidate the mechanism of AD and for development of AD drugs.

METHODS

We developed a sensitive and specific activity assay for BACE-1. The assay is based on a genetically engineered proenzyme that is specifically activated by BACE-1. The resulting active enzyme is measured with a chromogenic substrate. The use of 2 coupled reactions produces a detection limit as low as 0.4 pmol/L.

RESULTS

The assay detected BACE-1 activity in extracts of human brain tissue as well as, unexpectedly, in human cerebrospinal fluid (CSF). Gel electrophoresis and Western blotting identified the BACE-1 present in CSF as a truncated soluble form of the originally membrane-bound BACE-1.

CONCLUSION

Detection of the soluble form of BACE-1 in CSF, a relatively easily accessible biological fluid, may be useful for monitoring the effects of drug candidates in vivo and may have diagnostic or prognostic applications.

In vitro characterization of an in situ microdialysis sampling assay for elastase activity detection

A microdialysis sampling method has been developed to detect the in vitro presence of a proteolytic enzyme, porcine elastase, external to a microdialysis probe. Elastase converts the substrate, succinyl(Ala)(3)-p-nitroanilide (suc(Ala)(3)-p-NA), to p-nitroaniline (p-NA). The substrate, suc(Ala)(3)-p-NA, was locally delivered through the microdialysis probe to external solutions containing different elastase activities (0.025-0.5 units/mL). The product, p-NA, was recovered back into the probe. Dialysates containing both suc(Ala)(3)-p-NA and p-NA were quantified using HPLC-UV. Different microdialysis suc(Ala)(3)-p-NA extraction efficiencies (EE) were observed among different elastase-containing solutions (buffer and 0.3% agar solutions). The p-NA concentrations recovered back into the microdialysis probe correlated with the elastase activity external to the microdialysis probe. The greatest fraction of p-NA recovered as compared to substrate lost occurred with the highest flow rate used (5.0 microL/min). However, the highest concentrations of p-NA recovered occurred at the lowest flow rates. This method may allow for microdialysis sampling to be used as a means to study localized enzyme activity.

Carotid atherosclerotic plaques in patients with transient ischemic attacks and stroke have unstable characteristics compared with plaques in asymptomatic and amaurosis fugax patients

INTRODUCTION

Atherosclerotic carotid artery disease is responsible for a variety of clinical presentations, ranging from asymptomatic to cerebral ischemic events. Considering the upcoming use of noninvasive imaging modalities, plaque characteristics could serve as a marker in the selection of patients eligible for carotid endarterectomy (CEA). This would be more likely if characteristics corresponded with clinical manifestations and were predictive of future events. In this study, we hypothesized that plaque characteristics correlate with the clinical presentation of carotid artery disease.

METHODS

We included 404 patients undergoing a carotid endarterectomy (CEA). Ipsilateral clinical symptoms and duplex measurements were recorded. Patients could be asymptomatic (23.5%) or symptomatic with stroke (26.5%), transient ischemic attack (TIA) (36.1%), or amaurosis fugax (AFX) (13.9%). Plaques were stained and semi-quantitatively analyzed for the presence of macrophages, smooth muscle cells, collagen, calcifications, and thrombus. Plaques were categorized in three phenotypes by their overall presentation and the amount of fat. In addition, plaque matrix metalloproteinase (MMP) activity and cytokines expressions were measured.

RESULTS

Fibrous, fibro-atheromatous, and atheromatous plaques were observed in 30.2%, 35.6%, and 34.2%, respectively. Atheromatous plaques were more prevalent in patients with stroke and TIA compared with asymptomatic patients or patients with AFX (P = .001). Collagen staining was less evident in patients with TIA and stroke compared with asymptomatic patients or patients with AFX (P < .001). Plaques of patients with TIA and stroke showed significantly higher activity levels of MMP-8 and MMP-9 and higher levels of interleukin-8 compared with asymptomatic and AFX patients.

CONCLUSION

Plaque phenotype of patients with TIA is comparable to that of patients with stroke; whereas, the plaque phenotype of patients with AFX resembles the plaque phenotype of asymptomatic patients. Follow-up studies should be encouraged to determine whether plaque characteristics visualized by imaging techniques might help to identify patients most likely to benefit from CEA.

Assays of matrix metalloproteinases (MMPs) activities: a review

Measurement of matrix metalloproteinase (MMP) activity often remains a challenge, mainly in complex media. Two sets of methods are currently used. The first one measures the hydrolysis of natural protein substrates (labeled or not) and includes the popular zymography. These techniques which are quite sensitive, cannot generally be carried out on a continuous basis. The second one takes mainly advantage of the increase of fluorescence, which is associated to the hydrolysis of initially quenched fluorogenic peptide substrates. Quite recently, another group, which is a compromise between the other two, has been developed. It measures the hydrolysis of synthetic triple-helical peptide substrates. These different methods are described and discussed.

Matrix metalloproteinase-1 up-regulation by hepatocyte growth factor in human dermal fibroblasts via ERK signaling pathway involves Ets1 and Fli1

In this study, we clarified the molecular mechanism(s) underlying the regulation of matrix metalloproteinase (MMP)-1 gene by hepatocyte growth factor (HGF) in cultured human dermal fibroblasts. HGF induced MMP-1 protein as well as mRNA at a transcriptional level via extracellular signal-regulated kinase (ERK) signaling pathway. The region in the MMP-1 promoter mediating the inducible responsiveness to HGF, defined by the transient transfection analysis of the serial 5′ deletion constructs, contained an Ets binding site. Mutation of this Ets binding site abrogated the HGF-inducible promoter activity. Ets1 up-regulated the expression of MMP-1 promoter activity, whereas Fli1 had antagonistic effects on them. After HGF treatment, the protein level and the binding activity of Ets1 was increased and those of Fli1 was decreased, which were canceled by PD98059. These results suggest that HGF up-regulates MMP-1 expression via ERK signaling pathway through the balance of Ets1 and Fli1, which may be a novel mechanism of regulating MMP-1 gene expression.

Matrix metalloproteinase 8 (neutrophil collagenase) in the pathogenesis of abdominal aortic aneurysm

Background

Loss of elastin is the initiating event in abdominal aortic aneurysm (AAA) formation, whereas loss of collagen is required for continued expansion. The elastolytic matrix metalloproteinases (MMPs) 2 and 9 are well described, but the source of excessive collagenolysis remains undefined. The aim of this study was to determine the expression of MMP-8, a potent type I collagenase, in normal aorta and AAA.

Methods

Infrarenal aortic biopsies were taken from 40 AAA and ten age-matched normal aortas. The concentrations of MMP-8 protein and its inhibitors, tissue inhibitor of metalloproteinase (TIMP) 1 and TIMP-2, were quantified by enzyme-linked immunosorbent assay. Immunohistochemistry was used to localize MMP-8 expression.

Results

MMP-8 concentrations were significantly raised in AAA compared with normal aorta (active MMP-8: 4·5 versus 0·5 ng per mg protein, P &lt; 0·001; total MMP-8: 16·6 versus 2·8 ng per mg protein, P &lt; 0·001). Levels of TIMP-1 and TIMP-2 were significantly lower in AAA than in normal aortic samples (TIMP-1: 142·2 versus 302·8 ng per mg protein; P = 0·010; TIMP-2: 9·2 versus 33·1 ng per mg protein, P &lt; 0·001). Immunohistochemistry localized MMP-8 to mesenchymal cells within the adventitia of the aortic wall.

Conclusion

The high concentration of MMP-8 in aortic aneurysms represents a potent pathway for collagen degradation, and hence aneurysm formation and expansion.

Age-related changes in plaque composition

OBJECTIVE

The extent of atherosclerotic plaque burden and the incidence of atherosclerosis-related cardiovascular events accelerate with increasing age. The composition of the plaque is associated with plaque thrombosis and acute coronary occlusion. Surprisingly, however, the relation between advancing age and atherosclerotic plaque composition is still unclear. In the present study, we investigated the association between plaque characteristics and advancing age in a population of patients with haemodynamically significant carotid artery stenosis.

METHODS

Patients (N=383), ages 39-89 years, underwent carotid endarterectomy (CEA). Morphometric analysis was performed on the dissected atherosclerotic plaques to study the prevalence of fibrous and atheromatous plaques. Picro sirius red, haematoxylin eosin, alfa actin and CD68 stainings were performed to investigate the extent of collagen, calcification, smooth muscle cells and macrophages in carotid plaques, respectively. The presence of metalloproteinases-2 and -9 was assessed by ELISA.

RESULTS

With aging, a decrease in fibrous plaques and an increase in atheromatous plaques were observed. This was accompanied by an age-associated decrease in smooth muscle cell content in carotid plaques. Macrophage content slightly increased with age. In addition, total matrix metalloprotease (MMP)-2 was negatively and MMP-9 positively related with age. Differences in plaque phenotype were most prominent for the youngest age quartile compared with older age quartiles.

CONCLUSIONS

With increasing age, the morphology of atherosclerotic plaques from patients with carotid artery stenosis changes. Plaques become more atheromatous and contain less smooth muscle cells with increasing age. Local inflammation and MMP-9 levels slightly increased with age in plaques obtained from patients suffering from haemodynamically significant advanced atherosclerotic lesions.

Effects of hepatocyte growth factor on the expression of type I collagen and matrix metalloproteinase-1 in normal and scleroderma dermal fibroblasts

We investigated the direct effect of hepatocyte growth factor (HGF) on the expression of type I collagen in normal and scleroderma dermal fibroblasts, and analyzed the mechanisms underlying the effect in vitro. HGF did not change the protein expression of type I procollagen in the medium of normal human fibroblasts, whereas it reduced the expression in scleroderma fibroblasts. But mRNA levels and the promoter activity of alpha2(I) collagen gene were not significantly affected by HGF in either of the cells. On the other hand, matrix metalloproteinase-1 expression or activity was increased by HGF in both cells, but HGF had stronger effects in scleroderma fibroblasts than normal fibroblasts. Scleroderma fibroblasts overexpressed c-met protein, the receptor for HGF. The overexpression in scleroderma fibroblasts was abolished by the addition of antisense transforming growth factor (TGF)-beta1 oligonucleotide. Our study indicated that HGF may reduce type I collagen accumulation only in scleroderma fibroblasts by enhancing collagenolysis activity, probably because of the overexpression of c-met because of autocrine TGF-beta signaling. Thus, further investigation of the effects of HGF on collagen metabolism may contribute to the treatment of fibrosis in scleroderma.

Regulation of fibrogenic/fibrolytic genes by platelet-derived growth factor C, a novel growth factor, in human dermal fibroblasts

Platelet-derived growth factor (PDGF) is a potent mitogenic and chemotactic cytokine, and PDGF-C is a novel growth factor belonging to the PDGF family. In this study, to determine whether this growth factor can contribute to fibrosis and tissue remodeling, we examined the effect of PDGF-CC on the expression of fibrogenic/fibrolytic genes such as type I collagen, fibronectin (FN), matrix metalloproteinases (MMPs), and their inhibitors (TIMPs) in normal human dermal fibroblasts in vitro. PDGF elevated the levels of MMP-1 or TIMP-1 protein as well as mRNA, whereas this cytokine had no influence on the expression of type I collagen, FN, or TIMP-2. PDGF-CC also increased the levels of MMP-1 catalytic activity in the cultured media and mRNA expression, which was paralleled that on the levels of promoter activation. Additionally, PDGF-CC induced the mitogenic and migratory activity of human dermal fibroblasts in a dose-dependent manner. On the other hand, we also determined the specificity of the inhibitory effect of monoclonal antibodies against PDGF-CC generated by immunizing balb/c mice with recombinant human PDGF-CC. This antibody could inhibit the regulatory effects of MMP-1 or TIMP-1 synthesis as well as the mitogenic effects on human dermal fibroblasts induced by PDGF-CC, whereas this antibody did not affect those induced by other PDGF forms such as PDGF-AA, -AB, or -BB. These results suggest that this cytokine plays a role in the tissue remodeling.

Metalloproteinase inhibition by batimastat does not reduce neointimal thickening in stented atherosclerotic porcine femoral arteries

BACKGROUND

Vascular injury results in specific temporal patterns of increased matrix metalloproteinase (MMP) activity. MMPs are known to play a role in remodeling and neointimal (NI) thickening. Although in vitro data on the role of metalloproteinases and their inhibitors on smooth muscle cell migration and proliferation are compelling, evidence for inhibition of NI thickening in vivo is inconsistent and is mostly generated in models of balloon angioplasty instead of the more prevalent stent placement. Data from atherosclerotic models are scarce. The objective of the study was to investigate whether the nonspecific MMP inhibitor batimastat, in concentrations known to influence remodeling, could also inhibit NI thickening following stent placement in an atherosclerotic model.

METHODS

Stents were placed in atherosclerotic femoral arteries in Yucatan micropigs on a high cholesterol diet and followed for 6 weeks. Batimastat or vehicle was administered intraperitoneally. NI thickening was assessed by morphometry.

RESULTS

The main finding was that batimastat did not result in a significant decrease in NI thickness. Only following correlation to the amount of preexisting plaque was the difference of 146 microm (19%) statistically significant. Batimastat did not impair wound healing following stenting.

CONCLUSION

Batimastat does not significantly influence the degree of NI thickening at 6 weeks following stenting of atherosclerotic porcine femoral arteries, except when correlated to plaque thickness. Batimastat does not affect vascular wound healing.

Cathepsin K is the principal protease in giant cell tumor of bone

Giant cell tumor (GCT) of bone is a neoplasm of bone characterized by a localized osteolytic lesion. The nature of GCT is an enigma and the cell type(s) and protease(s) responsible for the extensive localized clinicoradiological osteolysis remain unresolved. We evaluated protease expression and cellular distribution of the proteolytic machinery responsible for the osteolysis. mRNA profiles showed that cathepsin K, cathepsin L, and matrix metalloproteinase (MMP)-9 were the preferentially expressed collagenases. Moderate expression was found for MMP-13, MMP-14, and cathepsin S. Specific protease activity assays revealed high cathepsin K activity but showed that MMP-9 was primarily present (98%) as inactive proenzyme. Activities of MMP-13 and MMP-14 were low. Immunohistochemistry revealed a clear spatial distribution: cathepsin K, its associated proton pump V-H(+)-ATPase, and MMP-9 were exclusively expressed in osteoclast-like giant cells, whereas cathepsin L expression was confined to mononuclear cells. To explore a possible role of cathepsin L in osteolysis, GCT-derived, cathepsin L-expressing, mononuclear cells were cultured on dentine disks. No evidence of osteolysis by these cells was found. These results implicate cathepsin K as the principal protease in GCT and suggest that osteoclast-like giant cells are responsible for the osteolysis. Inhibition of cathepsin K or its associated proton-pump may provide new therapeutic opportunities for GCT.

Unstable Carotid Plaques Exhibit Raised Matrix Metalloproteinase-8 Activity

BACKGROUND

The fibrous cap of atherosclerotic plaques is composed predominantly of type I and III collagen. Unstable carotid plaques are characterized by rupture of their cap, leading to thromboembolism and stroke. The proteolytic mechanisms causing plaque disruption are undefined, but the collagenolytic matrix metalloproteinase (MMP) -1, -8, and -13 may be implicated. The aim of this study was to quantify the concentrations of these collagenases in carotid plaques and to determine their relationship to markers of plaque instability.

METHODS AND RESULTS

Atherosclerotic plaques were collected from 159 patients undergoing carotid endarterectomy. The presence and timing of carotid territory symptoms were ascertained. Preoperative embolization was recorded by transcranial Doppler. Each plaque was assessed for histological features of instability. Plaque MMP concentrations were quantified with ELISA. Significantly higher concentrations of active MMP-8 were observed in the plaques of symptomatic patients (20.5 versus 11.4 ng/g; P=0.0002), in plaques of emboli-positive patients (22.7 versus 13.5 ng/g; P=0.0037), and in those plaques showing histological evidence of rupture (20.8 versus 14.7 ng/g; P=0.0036). No differences were seen in the levels of MMP-1 and MMP-13. Immunohistochemistry, in situ hybridization, and colocalization studies confirmed the presence of MMP-8 protein and mRNA within the plaque, which colocalized with macrophages.

CONCLUSIONS

These data suggest that the active form of MMP-8 may be partly responsible for degradation of the collagen cap of atherosclerotic plaques. This enzyme represents an attractive target for drug therapy aimed at stabilizing vulnerable plaques.

Crosslinking and G-protein functions of transglutaminase 2 contribute differentially to fibroblast wound healing responses

Tissue transglutaminase (TG2) affects cell-matrix interactions in cell spreading, migration and extracellular matrix (ECM) reorganisation. Using fibroblasts deficient in TG2 or overexpressing normal or crosslinking-deficient enzyme, we show that the extracellular crosslinking activity and intracellular G-protein function in signal transduction contribute differentially to regulation of cell-matrix interactions. TG2-deficient cells displayed normal attachment but delayed spreading on ECM substrata and defects in motility unrelated to crosslinking. Blocking antibodies to TG2 failed to induce similar defects in normal fibroblasts. TG2-deficient fibroblasts had defects in focal adhesion turnover and stress fibre formation, showed changes in focal adhesion kinase (FAK) phosphorylation and failed to activate protein kinase C alpha (PKCalpha). Phospholipase C (PLC) and PKCalpha inhibitors blocked spreading of normal fibroblasts whilst PKC activators induced spreading in TG2-deficient cells. In contrast, ECM remodelling was not only compromised by TG2 deficiency but also by overexpression of dominant negative enzyme and TG inhibitors. TG2 activity increased matrix tension and was required for membrane type 1-MMP (MT1-MMP)-dependent activation of MMP-2. Our results demonstrate that TG2 is involved in the control of dynamic adhesion formation in cell spreading and migration via regulation of phospholipase C activity. By virtue of its crosslinking activity, the enzyme plays a central role in regulating ECM remodelling.

The matrix metalloproteinase inhibitor prinomastat enhances photodynamic therapy responsiveness in a mouse tumor model

Photodynamic therapy (PDT) clinical results are promising; however, tumor recurrences can occur and, therefore, methods for improving treatment efficacy are needed. PDT elicits direct tumor cell death and microvascular injury as well as expression of angiogenic, inflammatory, and prosurvival molecules. Preclinical studies combining antiangiogenic drugs or cyclooxygenase-2 inhibitors with PDT show improved treatment responsiveness (A. Ferrario et al., Cancer Res 2000;60:4066-9; A. Ferrario et al., Cancer Res 2002;62:3956-61). In the present study, we evaluated the role of Photofrin-mediated PDT in eliciting expression of matrix metalloproteinases (MMPs) and modulators of MMP activity. We also examined the efficacy of a synthetic MMP inhibitor, Prinomastat, to enhance tumoricidal activity after PDT, using a mouse mammary tumor model. Immunoblot analysis of extracts from PDT-treated tumors demonstrated strong expression of MMPs and extracellular MMP inducer along with a concomitant decrease in expression of tissue inhibitor of metalloproteinase-1. Gelatin zymography and enzyme activity assays performed on protein extracts from treated tumors confirmed the induction of both latent and enzymatically active forms of MMP-9. Immunohistochemical analysis indicated that infiltrating inflammatory cells and endothelial cells were primary sources of MMP-9 expression after PDT, whereas negligible expression was observed in tumor cells. Administration of Prinomastat significantly improved PDT-mediated tumor response (P = 0.02) without affecting normal skin photosensitization. Our results indicate that PDT induces MMPs and that the adjunctive use of an MMP inhibitor can improve PDT tumor responsiveness.

Characterization of Mca-Lys-Pro-Leu-Gly-Leu-Dpa-Ala-Arg-NH2, a fluorogenic substrate with increased specificity constants for collagenases and tumor necrosis factor converting enzyme

Matrix metalloproteinases (MMPs) and the related tumor necrosis factor converting enzyme (TACE) are involved in tissue remodeling, cell migration, and processing of signaling molecules, such as cytokines and adhesion molecules. Fluorescence-quenched peptide substrates have been widely used to quantitate the actual enzymatic activity of MMPs. However, the various MMPs have very different specific activities toward these substrates. This restricts their value for the determination of composite proteolytic activity of mixtures of metalloproteinases in biological fluids. The N-terminal elongation of the most widely used MMP substrate (FS-1) with a Lys to the sequence Mca-Lys-Pro-Leu-Gly-Leu-Dpa-Ala-Arg-NH(2) (FS-6) yields a fluorogenic peptide with improved substrate properties. As compared to FS-1, the specificity constant (kcat/Km) of FS-6 for collagenases (MMP-1, MMP-8, MMP-13) and MT1-MMP (MMP-14) is increased two- to ninefold and threefold, respectively, while those for gelatinases and matrilysin remain equally high. Using high-performance liquid chromatography-fluorescence detection, MMP activity can be quantitated in the picomolar range. FS-6 shows up to twofold higher specificity constants (kcat/Km of 0.8x10(6)M(-1)s(-1)) for TACE, as compared to standard substrates Mca-PLAQAV-Dpa-RSSSAR-NH(2) and Dabcyl-LAQAVRSSSAR-EDANS. FS-6 is fully water soluble and thus allows measurement of metalloproteinase activity in tissue culture conditions, e.g., on the surface of viable cells in situ.

The inhibitory receptor FcgammaRII reduces joint inflammation and destruction in experimental immune complex-mediated arthritides not only by inhibition of FcgammaRI/III but also by efficient clearance and endocytosis of immune complexes

Studies of FcgammaRII-/- mice identified the inhibitory function of this receptor in joint inflammation and cartilage destruction induced with immune complexes (ICs). To extend our insight in the role of FcgammaRII in arthritis, we explored the role of FcgammaRII in the absence of activating receptors I and III using FcgammaRI/III-/- as well as FcgammaRI/II/III-/- mice. When antigen-induced arthritis (AIA) was elicited, which is a mixture of T cell and IC-driven inflammation, arthritis was almost absent at day 7 in FcgammaRI/III-/- mice. Remarkably, in FcgammaRI/II/III-/- mice, this model induced a tremendously increased arthritis as compared to wild-type controls. This implies that FcgammaRII regulates joint inflammation also in the absence of activating FcgammaRI and III. To confirm the IC specificity of this finding, similar studies were done with ICs or zymosan as arthritogenic stimuli. Strongly elevated inflammation was found in FcgammaRI/II/III-/- mice with IC but not with zymosan. Clearance studies identified accumulation of IgG in the knee joint in the absence of FcgammaRII. Moreover, macrophages expressing only FcgammaRII showed prominent endocytosis of preformed soluble ICs not different from controls. In total absence of FcgammaR (FcgammaRI/II/III-/-), macrophages completely failed to endocytose ICs. Although joint inflammation was much higher in AIA arthritic knee joints of FcgammaRI/II/III-/- and the inflammatory cells still expressed an inflammatory phenotype, severe cartilage destruction (MMP-mediated neoepitopes in the matrix and chondrocyte death) was completely prevented in contrast to the marked destruction which was observed in the wild-type. Our study indicates that FcgammaRII reduces joint inflammation in the absence of activating FcgammaR by promoting endocytosis and clearance of ICs from the joint. Infiltrating cells, which fail to express activating FcgammaR although they still become stimulated are no longer capable of inducing severe cartilage destruction.