Determination of gelatinase-A (MMP-2) activity using a novel immunocapture assay

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.

In situ and multisubstrate detection of elastase enzymatic activity external to microdialysis sampling probes using LC-ESI-MS

Extracellular proteases play significant roles in mammalian development and disease. Enzymatic activity external to a microdialysis sampling probe can be determined by infusing judicious choices of substrates followed by collecting and measuring the products. Porcine pancreatic elastase was used as a model enzyme with two substrates possessing different cleavage sites, N-methoxysuccinyl-Ala-Ala-Pro-Val-7-amino-4-methylcoumarin (FL-substrate) and N-succinyl-Ala-Ala-Ala-p-nitroanilide (UV-substrate). These substrates were infused through the microdialysis sampling probe to a solution containing elastase. The resulting four products and the remaining two substrates were collected into the dialysate and were subsequently analyzed off-line using liquid chromatography-mass spectrometry (LC-MS) with electrospray ionization (ESI). All analytes were identified using extracted ion chromatograms of m/z 628 (FL-substrate), m/z 452 (UV-substrate), m/z 471 (N-methoxysuccinyl-Ala-Ala-Pro-Val, FL-NTP), m/z 332 (N-succinyl-Ala-Ala-Ala, UV-NTP), m/z 176 (7-amino-4-methylcoumarin, AMC), and m/z 139 (p-nitroaniline, pNA). FL-NTP and FL-substrate exhibited 10-fold higher ion production as compared to AMC with equimolar standards. Microdialysis sampling combined with LC-ESI-MS detection allowed for in situ determination of the enzymatic activity of a protease external to the microdialysis probe when using different peptide-based substrates.

Increased mucosal matrix metalloproteinase-1, -2, -3 and -9 activity in patients with inflammatory bowel disease and the relation with Crohn's disease phenotype

BACKGROUND AND OBJECTIVE

Matrix metalloproteinases are associated with matrix turnover in both physiological and pathological conditions. We postulate an association between aberrant matrix metalloproteinases proteolytic activity and the intestinal tissue destruction, seen in patients with Crohn's disease and/or ulcerative colitis.

MATERIALS AND METHODS

Surgically resected inflamed and non-inflamed ileum and colon with/without extensive fibrosis from 122 Crohn's disease, 20 ulcerative colitis and 62 control patients were homogenized. Protein levels of matrix metalloproteinases and tissue inhibitor of metalloproteinases were measured by enzyme-linked immunosorbent assays (ELISA), while matrix metalloproteinases and myeloperoxidase activity were measured by specific activity assays.

RESULTS

Expression of total levels of matrix metalloproteinases-1, -2, -3 and -9 relative to tissue inhibitor of metalloproteinases-1 and -2 was increased in inflamed inflammatory bowel disease compared to non-inflamed inflammatory bowel disease and control intestinal mucosa. Also, net matrix metalloproteinases-1, -2, -3 and -9 activity in inflamed inflammatory bowel disease was increased, with similar expression profiles in Crohn's disease and ulcerative colitis. Within inflamed inflammatory bowel disease, a close correlation of matrix metalloproteinases with myeloperoxidase was observed. The expression of matrix metalloproteinases and tissue inhibitor of metalloproteinases was similar in inflamed Crohn's disease tissue with or without extensive fibrosis and not related to fistulizing disease.

CONCLUSIONS

We have shown increased net matrix metalloproteinases activity in intestinal inflammatory bowel disease tissue, likely to contribute to the tissue damage and remodelling seen in inflammatory bowel disease.

Platelets release active matrix metalloproteinase-2in vivoin humans at a site of vascular injury: lack of inhibition by aspirin

When stimulated in vitro, human platelets release matrix metalloproteinase-2 (MMP-2) that, in turn, potentiates platelet activation. The present study investigated if MMP-2 is released from activated platelets in vivo in humans and whether aspirin inhibits this release. MMP-2 levels were measured by zymography, immunoblotting, flow-cytometry and an activity assay system, in plasma prepared from blood emerging from a skin wound inflicted for the measurement of the bleeding time (shed blood) and simultaneously from venous blood in 27 healthy human volunteers. In a subgroup, the same measurements were carried out before and 1 h after aspirin intake. MMP-2 was significantly higher in shed blood than in venous blood and increased progressively, consistent with ongoing platelet activation. A significant correlation was evident between platelet number and MMP-2 in shed blood; platelet MMP-2 content in shed blood was lower than that of platelets in venous blood. The level of active MMP-2 released by activated platelets in vivo was within the range of concentrations that potentiate platelet activation. Aspirin did not reduce MMP-2 release in vivo. In conclusion, MMP-2 is released from platelets in vivo in humans at a localised site of vessel wall damage in amounts sufficient to potentiate platelet aggregation; aspirin does not reduce this release.

Matrix metalloproteinases in premature coronary atherosclerosis: influence of inhibitors, inflammation, and genetic polymorphisms

Matrix metalloproteinases (MMPs) are thought to participate in the pathogenesis of coronary artery disease (CAD), particularly in the occurrence of acute coronary syndrome (ACS). Little is known about human in vivo MMP regulation in CAD. The expression and regulation of MMPs and their tissue inhibitors (TIMPs) were evaluated in premature CAD. The distribution of MMP-3 5A/6A and MMP-9 C/T promoter polymorphisms and MMP-9 A/G exon-6 polymorphism were investigated in 200 consecutive male premature CAD patients (aged < or = 55 years) and 201 age-matched male blood donors. Plasma concentrations/activities of MMP-2 and MMP-9 were also measured, as were plasma concentrations of MMP-3, TIMP-1, and TIMP-2 in 80 patients (49 with ACSs and 31 with stable CAD) and 40 controls. Inflammation markers were also obtained. MMP genetic polymorphism distributions did not vary between patients and controls and did not seem to influence their respective MMP plasma levels. Patients showed increased MMP-9 and TIMP-1 concentrations and decreased TIMP-2 concentration and MMP-2 total activity (all P < or = 0.002). Overall, TIMP-1 correlated with C-reactive protein (CPR) (r = 0.594, P < 0.001) and haptoglobin (r = 0.276, P = 0.005), whereas MMP-2 activity correlated inversely with haptoglobin (r = -0.195, P = 0.032). Blood glucose correlated positively with TIMP-1 concentration (r = 0.711, P < 0.001) and negatively with MMP-2 activity (r = -0.250, P = 0.006). In conclusion, MMP and TIMP plasma levels in premature CAD are linked to clinical presentation and markers of inflammation and metabolic disorders rather than to genetic polymorphisms.

Vaginal versus oral indomethacin in a rabbit model for non-infection-mediated preterm birth: an alternate tocolytic approach

OBJECTIVE

We examined the hypotheses that vaginal indomethacin is more effective for prolonging gestation, and mediates its tocolytic actions via changes in cervical matrix metalloproteinase (MMP) activity, compared to oral.

STUDY DESIGN

Pregnant rabbits induced with mifepristone received oral or vaginal indomethacin; or oral or vaginal vehicle once daily for 2 days. Premature delivery, fetal ductus arteriosus, and cervical MMP activity were assessed.

RESULTS

Vaginal indomethacin delayed delivery >72 hours in 100% of the rabbits, extending gestation to 28.2 +/- 0.5 (P < .01) versus 26.4 +/- 0.3, 25.8 +/- 0.5, and 26.5 +/- 0.3 days, for vaginal placebo, oral indomethacin, and oral vehicle, respectively. Fetal ductus arteriosus was patent in all groups. Vaginal indomethacin decreased MMP-1, -8, and -9 activities and increased TIMP-1 levels in the cervix.

CONCLUSION

Vaginal indomethacin is more effective than oral for prolonging gestation in the rabbit. Its tocolytic effects may be mediated, in part, by alterations in cervical MMP activity.

Effects of Antenatal Betamethasone on Maternal and Fetoplacental Matrix Metalloproteinases 2 and 9 Activities in Human Singleton Pregnancies

BACKGROUND

A single course of antenatal betamethasone is administered to women at risk of preterm labor to advance fetal lung maturation. Matrix metalloproteinases (MMPs) are collagen-degrading enzymes that remodel extracellular matrix components during lung development. We tested the hypothesis that the effects of betamethasone on fetal lung maturation involve changes in MMP activity.

METHODS

We conducted a prospective, observational pilot study of three groups of singleton pregnancies. Group 1 (n = 21) was composed of women who were antenatally treated with a single course of betamethasone and who delivered < 37 weeks of gestation, group 2 (n = 7) was composed of matched untreated women who delivered < 37 weeks of gestation, and group 3 (n = 15) was composed of untreated women who delivered > 37 weeks of gestation. Maternal blood, mixed cord blood, and placental samples were collected at the time of delivery for MMP-2 and MMP-9 activity and tissue inhibitor of metalloproteinases (TIMP)-1 and -2 levels.

RESULTS

MMP-2 activity was significantly higher in the maternal, placental, and fetal compartments in group 1 compared with group 2 (p < .05). TIMP-2 levels were lower in groups 1 and 2 compared with group 3. Maternal TIMP-2 levels were higher (p < 0.003), whereas fetal TIMP-1 (p < .01) and MMP-9 to TIMP-1 ratios (p < .05) were lower when delivery was delayed more than 2 weeks following betamethasone treatment.

CONCLUSION

We conclude that elevated MMP-2 activity in the maternal and fetoplacental compartments may suggest a mechanism, in part, for betamethasone-induced fetal lung maturation.

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.

Inhibition of metalloproteinase activity by fruit extracts

While the metalloproteinase enzymes are essential for development and remodeling of tissues, aberrant over expression of these enzymes contributes to several pathologic conditions. In particular, metalloproteinase over expression in cancer plays a significant role in metastasis by providing a mechanism for invasion and spread. The data presented here indicate that water extracts of raspberries, blackberries and muscadine grapes inhibit the activities of metalloproteinases 2 and 9. This inhibition could contribute to the suppression of carcinogenesis by diets high in fruit content.

Assessment of serum matrix metalloproteinases MMP-2 and MMP-9 after human liver transplantation: increased serum MMP-9 level in acute rejection

BACKGROUND

Alterations in synthesis and breakdown of extracellular matrix components play a role in acute rejection after orthotopic liver transplantation (OLT). Matrix metalloproteinases (MMPs) are capable of degrading basement membranes and are involved in the process of tissue remodelling in inflammation and liver fibrosis.

METHODS

We examined MMP-2 and MMP-9 in serum of 33 patients before and during 1 year after OLT, in 60 controls as well as in some specimens of cirrhotic liver and control liver tissue.

RESULTS

Serum MMP-2 levels before OLT were significantly higher compared with controls and decreased approximately 50% after OLT. Also, the MMP-2 content of cirrhotic liver specimens was significantly higher compared with normal liver. MMP-9 in serum and liver tissue of patients were similar to controls, but serum levels showed a peak at 1 week after OLT. At this time-point, total and active/inhibitor-complexed MMP-9 was significantly higher in patients with rejection (n=13) compared with those without rejection (n=20). The relative amount of MMP-9 in the active/inhibitor-complexed form did not differ between each group over time. Immunohistochemical staining at 1 week after OLT showed increased numbers of MMP-9-positive inflammatory cells in the portal triads of patients with rejection.

CONCLUSIONS

Patients with acute allograft rejection have elevated serum levels of MMP-9 1 week after OLT, which was most likely derived from inflammatory cells. An increased MMP-2 serum level and liver tissue content was found in patients with cirrhosis, which decreased after OLT. These observations indicate active involvement of MMP-2 and -9 in end-stage liver disease and OLT.

Matrix-metalloproteinase Activity in First Trimester Placental Bed Biopsies in Further Complicated and Uncomplicated Pregnancies

Trophoblast invasion is partly regulated by matrix-metalloproteinases (MMPs). Aberrations in MMP-activity in early pregnancy are thought to play a role in the pathophysiology of pregnancy associated conditions like pre-eclampsia and intra-uterine growth restriction (IUGR). A direct relation however, has not been published. We tested the hypothesis that MMP activity in the decidua is compromised in the first trimester of pregnancies, which are complicated by hypertensive disorders or IUGR in later pregnancy. During chorionic villus biopsy, decidua is microscopically separated from the villi and stored. A selection of pregnancies complicated by pre-eclampsia or HELLP-syndrome or IUGR was made, with two matched controls each. Zymography was performed to identify the presence of MMPs, and subsequently immunohistochemistry for MMP-2 and -9 and cytokeratin 7 to examine differences between cases and controls. Next, a specific immuno-capture assay was used to determine the activity of MMP-1, -2, -3, -8, -9, and 13, total as well as active. Although presence of MMP-2 and MMP-9 was found, which corresponded with the immunohistochemistry, no significant differences could be demonstrated between activity of total MMP-2 and total MMP-9 in complicated and uncomplicated pregnancies. Activity of MMP-1, -3, -8 and -13 could not be detected.

IN CONCLUSION

our study confirms the presence of MMP-2 and -9 in first trimester placental bed biopsies, but does not support the current concept of deranged MMP-activity in early pregnancy in further complicated pregnancies.

Up-regulation of matrix metalloproteinase expression and activation following cyclical compressive loading of articular cartilage in vitro

Osteoarthritis (OA) results in articular cartilage degeneration and subchondral bone remodeling. Excessive or abnormal loading of the joint may contribute to matrix destruction by creating an imbalance between proteinases and their inhibitors. This study investigates whether cyclical loading regulates expression and/or activation of metalloproteinases 2 and 9 (MMPs) in articular cartilage explants. Gelatin zymography, reverse zymography, and MMP activity assays of mechanically loaded bovine cartilage explants (0.5 MPa, 1 Hz, 3 h) showed increased expression and activation of MMPs 2 and 9, whereas expression of the tissue inhibitors of MMPs was unaffected. This shows, for the first time that mechanical loading can influence tissue homeostasis generating an imbalance of proteinases and their inhibitors inducing turnover and/or catabolic events in cartilage.

Development of matrix metalloproteinase inhibitors in cancer therapy

The matrix metalloproteinases (MMPs) are a family of zinc-dependent proteinases involved in the degradation of the extracellular matrix. The MMPs have been implicated in the processes of tumor growth, invasion, and metastasis; are frequently overexpressed in malignant tumors; and have been associated with an aggressive malignant phenotype and adverse prognosis in patients with cancer. A number of MMP inhibitors are being developed for the treatment of cancer. The most extensively studied class of MMP inhibitors includes collagen peptidomimetics and nonpeptidomimetic inhibitors of the MMP active site, tetracycline derivatives, and bisphosphonates. The hydroxamate peptidomimetic inhibitor batimastat and its orally bioavailable analogue marimastat, which bind covalently to the zinc atom at the MMP-active site, were the first MMP inhibitors to be studied in detail. Marimastat is currently being studied in randomized clinical trials. The nonpeptidic MMP inhibitors were synthesized in an attempt to improve the oral bioavailability and pharmaceutical properties of the peptidic inhibitors. Several members of this class of compounds are undergoing evaluation in phase III clinical trials. The tetracyclines and, particularly, the nonantibiotic chemically modified tetracyclines, interfere with several aspects of MMP expression and activation and inhibit tumor growth and metastases in preclinical models. A representative agent of this class, Col-3, is currently undergoing phase I clinical trials. The development of the MMP inhibitors, like that of other targeted and predominantly antiproliferative compounds, poses a challenge because the paradigms that have governed the design of clinical oncology trials may not be relevant to this new class of agents. The anticipated need for long-term administration of these drugs, together with their cytostatic mechanism of action, will require novel clinical trial design strategies.

Increased gelatinase-A and gelatinase-B activities in malignant vs. benign breast tumors

Matrix metalloproteinases (MMP) types 2 and 9 (also known as gelatinase A and B) are thought to be causally involved in cancer invasion and metastasis. In normal as well as in malignant tissue, both these MMPs occur in multiple forms such as inactive precursors, active enzymes and enzyme-inhibitor complexes. Using newly developed quantitative activity assays, the levels of active MMP-2, total (active and activatable) MMP-2 and total MMP-9 were found to be significantly higher in breast carcinomas than in fibroadenomas. In addition, active MMP-2 and MMP-9 were detected more frequently in malignant than in benign breast carcinoma. These new quantitative activity assays are likely to be of use in studying the mechanism of action of both MMP-2 and -9, assessing their potential prognostic value in different cancers and in the design of MMP inhibitors for preventing cancer metastasis.