Peripheral blood levels of matrix metalloproteases-2 and -9 are elevated in patients with acute coronary syndromes

Positive correlation between CD137 expression and complex stenosis morphology in patients with acute coronary syndromes

BACKGROUND

CD137, a member of the tumor necrosis factor receptor superfamily, has been reported to be expressed highly in patients with acute coronary syndromes. However, limited information is available on the relationship between CD137 expression and complex stenosis morphology in patients with acute coronary syndromes.

METHODS

Our study included normal controls (n=50), patients with stable angina (SA) (n=80) and patients with acute coronary syndromes (ACS), including unstable angina (UA) (n=70) and acute myocardial infarction (AMI) (n=100). The expression of CD137 in peripheral monocytes was analyzed by flow cytometry. Serum soluble CD137 (sCD137), MMP-9 and MMP-3 levels were measured by enzyme-linked immunosorbent assay kit. All coronary stenoses with ≥50% diameter reduction were assessed by angiographic coronary stenosis morphology.

RESULTS

Patients with ACS(n=170) showed a significant increase of CD137 [23.6±5.7 mean fluorescence intensity (MFI)] expression in peripheral monocytes compared with control (8.4±2.6 MFI) and SA group (7.9±2.1 MFI) (p<0.001). sCD137 also showed higher level in patients with ACS(30.2±8.7 ng/ml) than in control (6.2±1.8 ng/ml) and SA group (7.1±2.1 ng/ml) (p<0.001). Serum MMP-3 and MMP-9 in patients with ACS were 2-times greater than those in control and SA group. A positive correlation was found between MMP-9, MMP-3 and CD137 expression in peripheral monocytes as well as sCD137 levels. An obvious correlation was also observed between soluble or membrane-bound CD137 expression and complex coronary stenoses (r1=0.5548, r2=0.4652, and p<0.001). In the logistic regression model, the independent predictors of ACS were sCD137 (odds ratio 2.671, 95% CI 1.718-4.153, P=0.000), MMP-9 (1.431, 1.043-1.964, P=0.026) and MMP-3 (1.368, 1.038-1.817, P=0.018).

CONCLUSION

Patients with ACS showed significantly positive correlation between CD137 expression and complex coronary stenosis morphology. We speculate that the increased CD137 expression might represent or reflect an instability of atherosclerotic plaques in patients with ACS.

Association of polymorphisms of zinc metalloproteinases with clinical response to stem cell therapy

AIM

The purpose of this study was to assess the associations of polymorphisms in two metalloproteinase genes-metalloproteinase-2 (MMP-2) and angiotensin converting enzyme (ACE)-with clinical response to autologous transplantation of mononuclear bone marrow cells (MBMC) in patients with acute myocardial infarction.

METHODS

The double centre study included 48 patients with a first acute myocardial infarction treated with primary coronary angioplasty, stent implantation and transplantation of MBMC. According to the changes in perfusion defect size, left ventricle ejection fraction, end-systolic volume and peak systolic velocity of the infracted wall (dSaMI) after cell therapy, the patients were retrospectively divided into group A (responders) and group B (non-responders). Genomic DNA was isolated from peripheral leukocytes by a standard technique using proteinase K. Three MMP-2 promoter (-1575G/A, -1306C/T and -790T/G) as well as I/D ACE gene polymorphisms were detected by PCR methods with restriction analyses (when necessary) according to standard protocols.

RESULTS

Of the 48 patients who received MBMC transplantation, 17 responded to the therapy. There were no significant differences in the prevalence of matrix metalloproteinase-2 triple genotype GGCCTT between responder/non-responder groups (71% versus 61%, p=0.375). Similarly, no differences in either genotype distribution or allelic frequencies of I/D ACE polymorphism between responders and non-responders to the cell therapy were observed (p=0.933). Compared to patients with ACE genotype ID or DD, the patients with ACE II genotype significantly improved in regional systolic LV function of the infarcted wall after implantations of MBMC (dSaMI - 0.4 versus 1.4 cm/s, p=0.037).

CONCLUSION

In our study, the ACE genotype II was associated with improvement of regional systolic LV function of the infarcted wall after implantations of MBMC. The detected polymorphism in matrix metalloproteinase-2 gene was not associated with clinical response to cell therapy.

Clinical significance of matrix metalloproteinase (MMP)-2 in patients with acute heart failure

The serum levels of matrix metalloproteinases (MMPs) increase during chronic heart failure (HF) and the MMP-2 are related to a poor prognosis. However, the roles of MMP-2 in acute HF (AHF) remain unclear. We investigated the change and clinical significance of MMP-2 in these conditions. The serum levels of MMP-2 were measured in 83 AHF patients before starting treatment (day 1), 3 (day 3) and 7 (day 7) days after admission, and before discharge (predischarge). MMP-2 decreased rapidly and significantly from day 3 to day 1 (902.9 ± 304.2 versus 1220.4 ± 330.5 ng/mL; P < 0.0001), whereas that of MMP-2 was not significantly different on day 7 and at predischarge (894.7 ± 278.9 and 920.0 ± 269.6 ng/mL, respectively) compared to day 3. We evaluated the relationships between ΔMMPs, defined as the changes in MMPs from day 1 to day 3 and HF events including cardiac death, readmission to hospital for HF, and uncontrollable HF. The MMP-2 value was significantly (P = 0.004) more decreased in the event-free group (381.4 ± 256.5 ng/mL) than in the event group (211.9 ± 225.5 ng/mL) between day 1 and day 3. The results of the multivariate logistic regression model for predicting HF events found that the specific factor for HF events was ΔMMP-2. Cutoff values of ΔMMP-2 were determined and event-free curves were constructed. Kaplan-Meier curves showed that the prognosis was significantly better among the patients with reductions in ΔMMP-2 values of more than 342 ng/mL. The serum levels of MMP-2 decreased with improvements in AHF. Rapid decreases in MMP-2 may be important for a better clinical outcome in patients with AHF.

Whole blood assay for elastase, chymotrypsin, matrix metalloproteinase-2, and matrix metalloproteinase-9 activity

The ability to measure protease activity in the blood is important for the development of future diagnostics and for biomedical research. Presently, protease assays require sample preparation, making them time-consuming, costly, less accurate, and unsuitable for point-of-care (POC) diagnostics. Recently, we demonstrated a unique method for measuring clinically relevant levels of trypsin activity in only a few microliters of whole blood. This assay utilizes a charge-changing fluorescent peptide substrate that produces a positively charged fluorescent product fragment upon cleavage by the target protease. Using a simple electrophoretic format, the fragments could be rapidly separated, concentrated, and detected directly from a whole blood sample. We now report on the development of new protease substrates for the measurement of elastase, chymotrypsin, matrix metalloproteinase (MMP)-2, and MMP-9 activity in whole blood. In these studies, detection limits ranging from 1 to 40 pg in 6 μL of 1× phosphate-buffered saline (PBS) (0.2-6 ng/mL) were achieved after a only 1 h reaction of enzyme and substrate. In subsequent experiments measuring spiked protease in whole blood (with endogenous protease present), detection limits ranging from 100 to 200 ng/mL were achieved after a 1 h reaction. Thus, these new substrates demonstrate broad applicability toward clinically relevant detection of important disease-relevant proteases.

Adenovirus-mediated sphingomyelin synthase 2 increases atherosclerotic lesions in ApoE KO mice

Background

Sphingomyelin synthase 2 (SMS2) contributes to de novo sphingomyelin (SM) biosynthesis. Its activity is related to SM levels in the plasma and the cell membrane. In this study, we investigated the possibility of a direct relationship between SMS and atherosclerosis.

Methods

The Adenovirus containing SMS2 gene was given into 10-week ApoE KO C57BL/6J mice by femoral intravenous injection. In the control group, the Adenovirus containing GFP was given. To confirm this model, we took both mRNA level examination (RT-PCR) and protein level examination (SMS activity assay).

Result

We generated recombinant adenovirus vectors containing either human SMS2 cDNA (AdV-SMS2) or GFP cDNA (AdV-GFP). On day six after intravenous infusion of 2 × 10¹¹ particle numbers into ten-week-old apoE KO mice, AdV-SMS2 treatment significantly increased liver SMS2 mRNA levels and SMS activity (by 2.7-fold, 2.3-fold, p < 0.001, respectively), compared to AdV-GFP treated mice. Moreover, plasma total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), triglyceride (TG), and sphingomyelin (SM) levels were significantly increased by 39% (p < 0.05), 42% (p < 0.05), 68% (p < 0.001), and 45% (p < 0.05), respectively. Plasma high-density lipoprotein cholesterol (HDL-C), phosphatidylcholine (PC), and PC/SM ratio were decreased by 42% (p < 0.05), 18% (p < 0.05), and 45% (p < 0.05), respectively. On day 30, the atherosclerotic lesions on the aortic arch of AdV-SMS2 treated mice were increased, and the lesion areas on the whole aorta and in the aortic root were significantly increased (p < 0.001). Furthermore, the collagen content in the aorta root was significantly decreased (p < 0.01).

Conclusions

Our results present direct morphological evidence for the pro-atherogenic capabilities of SMS2. SMS2 could be a potential target for treating atherosclerosis.

Elevated levels of circulating matrix metalloproteinase-9 are associated with a dysregulated cortisol rhythm--A case-control study of coronary artery disease

A dysregulated cortisol pattern has been found to be associated with systemic inflammatory activity in patients with coronary artery disease (CAD). Matrix metalloproteinase (MMP)-9 is involved in both inflammation and matrix degradation and considered a main contributor to coronary plaque rupture. In this study, we hypothesized that a dysfunctional cortisol response also involved a failure to regulate systemic MMP-9 levels in CAD patients. Total MMP-9, active MMP-9 and the endogenous inhibitor TIMP-1 were measured in 30 CAD patients and 30 healthy controls. Morning and evening cortisol was measured in repeated saliva samples. Patients had higher levels of total and active MMP-9 (both p<0.01) and increased 24-h cortisol output (p<0.05) characterized by higher levels of evening cortisol (p=0.011). MMP-9 was associated with evening cortisol (p<0.001) independent of smoking and inflammatory markers. Compared with controls, patients also showed a blunted cortisol response to stress. After stress, the levels of MMP-9 became significantly reduced in controls whereas they remained unchanged in patients. The data indicate that MMP-9 is differently regulated in patients due to a dysfunctional hypothalamic-pituitary-adrenal (HPA) axis and emphasize the role of MMP-9 as a possible link between stress and cardiovascular disease.

Matrix metalloproteinases and membrane damage markers in sera of patients with acute myocardial infarction

Coronary artery disease is a multifunctional disease and represents one of the leading causes of death worldwide. Oxidative stress appears as an etiological factor for myocardial damage during acute myocardial infarction. Some data suggest that acute coronary syndromes may also be influenced by matrix metalloproteinases through degradation of the fibrous cap of vulnerable atherosclerotic lesions. It has been indicated that gelatinases A and B play a key role in acute myocardial infarction and deoxyribonuclease I has been postulated to be a novel early phase marker of disease. The aim was to study activity of gelatinases A and B in acute myocardial infarction and its association with some membrane damage markers. Seventy-five patients with disease and seventy-five healthy controls were enrolled. Activities of lactate dehydrogenase, malate dehydrogenase, and deoxyribonuclease I were estimated using standard spectrophotometric assay and isoforms of lactate and malate dehydrogenases were determined using direct zymography. Activity of dehydrogenases was significantly higher in patients, while deoxyribonuclease I was lower. Isoform 2 of lactate dehydrogenase was significantly higher in the patient group. Gelatinases A and B were detected only in patients group. The results suggest determination of serum malate dehydrogenase activity to be used as an additional parameter for acute myocardial infarction diagnosis. Those findings suggest important role of gelatinases A and B as biomarkers of early stage of acute myocardial infarction together with membrane damage parameters.

Nitroglycerin alters matrix remodeling proteins in THP-1 human macrophages and plasma metalloproteinase activity in rats

Several studies suggested that long-term nitrate therapy may produce negative outcomes in patient mortality and morbidity. A possible mechanism may involve nitrate-mediated activation of various extracellular matrix (ECM) proteases, particularly matrix metalloproteinase-9 (MMP-9), and adhesion molecules in human macrophages, leading to the destabilization of atherosclerotic plaques. We examined the gene and protein regulating effects on THP-1 human macrophages by repeated exposure to therapeutically relevant concentrations of nitroglycerin (NTG) and possible involvement of nuclear factor (NF)-κB signaling mechanism in mediating some of these observed effects. THP-1 human macrophages repeatedly exposed to NTG (at 10 nM, added on days 1, 4 and 7) exhibited extensive alterations in the expression of multiple genes encoding ECM proteases and adhesion molecules. These effects were dissimilar to those produced by a direct nitric oxide donor, diethylenetriamine NONOate. NTG exposure significantly up-regulated NF-κB DNA nuclear binding activity and MMP-9 protein expression, and reduced tissue inhibitor of metalloproteinase-1 (TIMP-1) expression; these effects were abrogated in the presence of the NF-κB inhibitor parthenolide (a chemical inhibitor derived from the feverfew plant). Further, we examined whether our in vitro findings (an elevated MMP-9/TIMP-1 ratio and gelatinase activity) can be translated to in vivo effects, in a rat model. Sprague-Dawley rats exposed continuously to NTG subcutaneously for 8 days via mini-osmotic pumps showed significant induction of plasma MMP-9 dimer concentrations and the expression of a complex of MMP-9 with lipocalin-2 or neutrophil gelatinase associated lipocalin (NGAL). Plasma gelatinase activity was significantly increased by NTG over the entire study period, attaining peak elevation at day 6. Plasma TIMP-1 protein was down-regulated significantly by day 2 and days 4-7 in the NTG-treated rats. Pharmacokinetic monitoring of NTG and its dinitrate metabolites indicated that concentrations were well within therapeutic levels observed in humans. Our studies indicate that clinically relevant concentrations of NTG not only altered ECM matrix by changing the expression of multiple genes that govern cellular integrity, affecting cellular MMP-9/TIMP-1 balance in THP-1 human macrophages possibly via NF-κB activation, but also led to systemic changes in MMP-9/TIMP-1 expression and gelatinase activity in rats. These effects may contribute to extracellular matrix degradation and possible atherosclerotic plaque destabilization.

The effects of obesity and polycystic ovary syndrome on serum lipocalin-2 levels: a cross-sectional study

BACKGROUND

Lipocalin-2 is a novel adipokine that appears to play a role in the development of insulin resistance. Serum lipocalin-2 levels are elevated in obese patients. Obesity and insulin resistance are cardinal characteristics of the polycystic ovary syndrome (PCOS). However, there are limited data on serum lipocalin-2 levels in patients with PCOS. The aim of the present study was to assess serum lipocalin-2 levels in PCOS.

METHODS

We studied 200 patients with PCOS and 50 healthy female volunteers.

RESULTS

Serum lipocalin-2 levels were slightly higher in women with PCOS compared with controls (65.4 +/- 34.3 vs. 60.3 +/- 26.0 ng/ml, respectively) but this difference did not reach statistical significance. In contrast, lipocalin-2 levels were higher in overweight/obese women with PCOS than in normal weight women with the syndrome (76.2 +/- 37.3 vs. 54.5 +/- 27.2 ng/ml, respectively; p < 0.001). Serum lipocalin-2 levels were also higher in overweight/obese controls compared with normal weight controls (70.1 +/- 24.9 vs. 50.5 +/- 23.7 ng/ml, respectively; p = 0.004). In the total study population (patients with PCOS and controls), lipocalin-2 levels were independently correlated with the body mass index (p < 0.001). In women with PCOS, lipocalin-2 levels were independently correlated with the waist (p < 0.001).

CONCLUSIONS

Obesity is associated with elevated serum lipocalin-2 levels. In contrast, PCOS does not appear to affect lipocalin-2 levels.

Positive correlation between pregnancy-associated plasma protein-A level and OX40 ligand expression in patients with acute coronary syndromes

OBJECTIVE

Increasing evidence show that serum pregnancy-associated plasma protein-A (PAPP-A) and OX40 ligand (OX40L) expression have been implicated in acute coronary syndromes (ACS). We investigated the relationship between PAPP-A level and OX40L in serum and membrane-bound OX40L in patients with ACS.

METHODS

The present study included normal controls (n=30), patients with stable angina (SA) (n=60) and patients with ACS, including unstable angina (UA) (n=50) and acute myocardial infarction (AMI) (n=30). Serum concentrations of PAPP-A and soluble OX40L (sOX40L) were determined with Elisa, whereas the expression of OX40L on monocytes were analyzed with flow cytometry.

RESULTS

The expression of OX40L in peripheral monocytes in patients with UA [25.6±5.5 mean fluorescence intensity (MFI)] and AMI (29.4±6.3MFI) were significantly higher than those in patients with SA (10.6±2.8MFI) and controls (11.1±3.5MFI). Both sOX40L and PAPP-A in patients with UA (15.7±4.9ng/mL, 25.4±6.8μg/mL, respectively) and AMI (17.1±5.3ng/mL, 26.3±5.6μg/mL, respectively) were significantly higher than those in patients with SA (3.4±1.4ng/mL, 9.6±2.1μg/mL, respectively) and controls (3.9±1.3ng/mL, 8.5±2.8μg/mL, respectively) (P<0.001). Interestingly, a positive correlation was found between sOX40L, membrane-bound OX40L and serum PAPP-A levels (r(1)=0.54, r(2)=0.51; P<0.0001). Both serum and membrane-bound OX40L and PAPP-A levels significantly correlated with complex coronary stenosis (r(1)=0.56, r(2)=0.55, r(3)=0.40; P<0.001).

CONCLUSION

PAPP-A level was significantly related to soluble and membrane-bound OX40L in patients with ACS. Enhanced level of serum PAPP-A and sOX40L might represent a prognostic marker for coronary disease activity.

Platelets release matrix metalloproteinase-2 in the coronary circulation of patients with acute coronary syndromes: possible role in sustained platelet activation

AIMS

To investigate whether selected matrix metalloproteinases (MMPs) are released in the coronary circulation of patients with acute coronary syndrome (ACS), whether this release is related to platelet activation, and whether it contributes to sustained platelet activation.

METHODS AND RESULTS

Blood from the aorta (Ao) and the coronary sinus (Cs) was obtained from 21 controls (non-cardiac chest pain), 24 stable angina (SA), and 30 ACS patients, before performing percutaneous transluminal coronary angioplasty. Selected MMPs, some platelet activation- and atheroma-related markers, and the platelet activation-potentiating activity of plasma were measured. Total MMP-2, active MMP-2, and MMP-9 were released in the coronary circulation of patients with ACS, but not of those with SA or controls. Similarly, transcoronary gradients of β-thromboglobulin (β-TG) and platelet factor 4, two platelet-specific proteins, and of soluble CD40L and secretory phospholipase A₂ (sPLA₂), markers of inflammation and platelet activation, were higher in ACS patients than in the other groups. In contrast, plasma monocyte chemoattractant protein-1, a platelet-unrelated marker of atherogenesis, was not increased in the Cs compared with Ao in any of the groups. Transcoronary gradients of both β-TG and sPLA₂ correlated with those of total and active MMP-2 in ACS, but not in controls or SA. Plasma from the Cs of ACS patients potentiated platelet activation, an effect suppressed by the specific MMP-2-inhibitor, tissue inhibitor of MMP-2 (TIMP-2).

CONCLUSION

Matrix metalloproteinase-2 is released in the coronary circulation of ACS patients, derives in part from activated platelets, and may contribute to sustained intracoronary platelet activation.

Effects of telmisartan on markers of ventricular remodeling in patients with acute myocardial infarction: comparison with enalapril

Enalapril is effective in the suppression of left ventricular remodeling after acute myocardial infarction (AMI), but the effect of telmisartan is unclear. The consecutive 163 AMI patients underwent primary percutaneous coronary intervention and were randomized to telmisartan (n = 82) or enalapril (n = 81). Left ventriculography was performed in the acute and chronic (6 months) phases. Matrix metalloproteinase (MMP)-2 and MMP-9 activities were measured by zymography in the acute (days 1, 7, and 14) and chronic (6 months) phases. Plasma pentraxin3 (PTX3), a marker of vascular inflammation, was also measured. There were no adverse effects in the telmisartan group. The analysis of the left ventriculograms in the acute and chronic phases revealed no difference between the two groups. MMP-9 activities at days 7 and 14 and in the chronic phase were decreased compared to that at day 1 in both groups. MMP-2 activity was also decreased in the acute phase, but increased in the chronic phase in both groups. There was no difference in the plasma PTX3 level in the acute phase, but in the chronic phase, PTX3 was significantly lower in telmisartan than in enalapril group (2.6 ± 1.4 vs. 3.2 ± 1.6 ng/ml, p = 0.04). Telmisartan is well tolerated, shows similar effects on the markers of left ventricular remodeling to those of enalapril, and suppresses vascular inflammation more effectively than enalapril in AMI patients. Telmisartan can be an alternative to angiotensin converting enzyme inhibitor in patients with AMI.

[Gelatinases A and B activities in the serum of patients with various coronary artery disease stages]

BACKGROUND/AIM

The main characteristic of matrix metalloproteinases (MMPs) is the degradation of extracellular matrix. Synthesis of MMPs has been reported in coronary atherosclerotic lesions in patients with coronary disease (CD) suggesting a pathogenic role of MMPs in its development. Recently there is increasing evidence that gelatinase A (pro MMP-2) and gelatinase B (proMMP-9) play a pathogenic role in the development of the atherosclerotic plaques. The aim of the study was to determine, by the use of a gel image system, a possible presence of active gelatinases in the serum of the patients with CD, as well as if their activity is higher in these patients than in healthy people.

METHODS

By gelatin zymography we analyzed the activity of proMMP-2 and proMMP-9 in the serum of 50 patients with various coronary artery disease stages and in the serum of 15 healthy controls. The activity was measured by using a gel image system (Kodak Image 1D 3.6.).

RESULTS

ProMMP-2 and proMMP-9 activity was significantly higher in the serum of patients with CD compared to controls. There was higher activity of MMP-2 and MMP-9 in the serum of patients with acute myocardial infarction (AMI) compared to patients with stable angina pectoris, as well as higher proMMP-9 activity in patients with unstable angina pectoris compared to patients with stable angina pectoris.

CONCLUSION

ProMMP-2 and proMMP-9 participate in processes associated with destabilizing plaques and understanding the processes of MMPs activation and regulation may have significant benefits in clinical interpretation. The reported higher proMMP-2 and proMMP-9 activity in the serum of patients with CD suggests a role of proMMP-2 and proMMP-9 in prognostic stratification of these patients and in designing new drugs.

A timely diagnosis of myocardial infarction

The diagnosis of acute myocardial infarction currently rests on the measurement of troponin, a biomarker of myocardial necrosis. Unfortunately, the current generation troponin assays detect troponin only 6-9 h after symptom onset. This can lead to a delay in diagnosis and also excessive resource utilization when triaging patients who, ultimately, have noncardiac causes of acute chest pain. For these reasons, there has been extensive research interest in biomarkers that can detect and rule out myocardial infarction early after symptom onset. These include markers of myocardial injury, such as myoglobin, heart-type fatty acid binding protein, glycogen phosphorylase BB; hemostatic markers, such as D-dimer; and finally, inflammatory markers, such as matrix metalloproteinase 9. Recently, highly sensitive troponin assays have reported an early sensitivity for myocardial infarction of greater than 95%, although at a cost of reduced specificity. The optimal strategy with which to use these novel biomarkers and highly sensitive troponins has yet to be determined, and interpretation of their results in light of thorough clinical assessment remains essential.

Cardiac biomarkers - the old and the new: a review

Biomarkers are biological parameters that can be objectively measured and quantified as indicators of normal biologic processes, pathogenic processes, or responses to a therapeutic intervention. Typically thought of as disease process screening, diagnosing, or monitoring tools, biomarkers may also be used to determine disease susceptibility and eligibility for specific therapies. Cardiac biomarkers are protein components of cell structures that are released into circulation when myocardial injury occurs. They play a pivotal role in the diagnosis, risk stratification, and treatment of patients with chest pain and suspected acute coronary syndrome and those with acute exacerbations of heart failure. Cardiac markers are central to the new definition of acute myocardial infarction put forward by the American College of Cardiology and the European Society of Cardiology. Active investigation has brought forward an increasingly large number of novel candidate markers but few have withstood the test of time and become integrated into contemporary clinical care because of their readily apparent diagnostic, prognostic, or therapeutic utility.

Adiposity and low-grade systemic inflammation modulate matrix metalloproteinase-9 levels in Greek children with sleep apnea

BACKGROUND

Matrix metalloproteinase-9 (MMP-9) plasma levels correlate with C-reactive protein (CRP) concentrations and they are both increased in adults with obstructive sleep apnea (OSA). No studies have evaluated MMP-9 levels in children with sleep apnea and CRP is not consistently elevated in pediatric OSA. The aim of this investigation was to evaluate the association of severity of OSA, adiposity, and CRP with MMP-9 plasma levels in Greek children.

METHODS

Consecutive children with snoring who underwent polysomnography and were found to have OSA (obstructive apnea-hypopnea index-OAHI > or = 1 episode/hr) were recruited. Subjects without OSA (OAHI < 1 episode/hr) were included for comparison. Morning plasma MMP-9 and CRP were measured.

RESULTS

Twenty-nine children with moderate-to-severe OSA (age 5.4 +/- 1.5 years; OAHI 13.9 +/- 13.0 episodes/hr), 55 participants with mild OSA (6.4 +/- 2.6 years; OAHI 2.4 +/- 1.1 episodes/hr) and 22 subjects without OSA (6.8 +/- 2.6 years; OAHI 0.6 +/- 0.2 episodes/hr) were studied. Children with moderate-to-severe OSA were similar to those with mild OSA or without OSA regarding ln-transformed MMP-9 values (5.87 +/- 0.60 vs. 5.84 +/- 0.55 vs. 5.80 +/- 0.46; P > 0.05) and CRP concentrations (0.22 +/- 0.29 mg/dl vs. 0.21 +/- 0.36 vs. 0.13 +/- 0.16 mg/dl; P > 0.05). In multiple linear regression, body mass index (P = 0.027) and CRP levels (P = 0.008), but not OAHI or SpO(2) nadir (P > 0.05), were significantly related to MMP-9 values.

CONCLUSIONS

Adiposity and systemic inflammation unrelated to OSA severity, modulate MMP-9 levels in Greek children.

CD40 ligand shedding is regulated by interaction between matrix metalloproteinase-2 and platelet integrin alpha(IIb)beta(3)

BACKGROUND

CD40 ligand (CD40L, CD154) in the circulatory system is mainly contained in platelets, and surface-expressed CD40L on activated platelets is subsequently cleaved by proteolytic activity to generate soluble CD40L (sCD40L). However, the enzyme responsible for the shedding of CD40L in activated platelets has not been clearly identified yet. We have recently found that molecular interaction of matrix metalloproteinase-2 (MMP-2) with integrin alpha(IIb)beta(3) is required for the enhancement of platelet activation.

OBJECTIVES

To elucidate the biochemical mechanism of MMP-2-associated sCD40L release.

METHODS

Localization of MMP-2 and CD40L in platelets was analyzed by flow cytometry and fluorescence microscopy. The release of sCD40L from activated platelets was measured by enzyme-linked immunosorbent assay. MMP-2 binding to alpha(IIb)beta(3) was analyzed by immunoprecipitation and western blotting. Recombinant hemopexin-like domain and MMP-2-specific inhibitor were used to characterize the nature of MMP-2 binding and catalytic activity.

RESULTS

It was revealed that interaction of MMP-2 with alpha(IIb)beta(3) is required for effective production of sCD40L in activated human platelets. Platelet activation and release of sCD40L were significantly affected by inhibition of platelet-derived MMP-2 activity or by inhibition of binding between the enzyme and the integrin. It was also found in platelet-rich plasma that MMP-2 activity is responsible for generating sCD40L.

CONCLUSIONS

The results presented here strongly suggest that MMP-2 interacts with alpha(IIb)beta(3) to regulate the shedding of CD40L exposed on the surfaces of activated human platelets.

Activation of peripheral blood mononuclear cells and extracellular matrix and inflammatory gene profile in acute myocardial infarction

Inflammation and ECM (extracellular matrix) remodelling play important roles in LV (left ventricular) remodelling following acute MI (myocardial infarction). Previous studies show elevated plasma MMP (matrix metalloproteinase) levels in patients with acute MI, but their sources are not clear. The recruitment of mononuclear cells into the infarcted myocardium is critical for inflammatory responses, but their exact roles in LV remodelling have not been fully investigated, as it is difficult to isolate and study the function of regional inflammatory cells. To address these questions, we isolated PBMCs (peripheral blood mononuclear cells) from blood samples of patients with acute MI or stable angina, or healthy controls (n=14, 8 and 12 respectively). PBMCs were cultured for 24 h and the MMP9 level in the culture medium was measured by gelatin zymography, and MMP9 gene expression was measured by real-time PCR. Two superarrays (ECM and adhesion molecules, and common cytokines; 84 genes included in each array) were employed to screen gene expression profiles by PBMCs in five patients with acute MI and five controls. We found that MMP9 expression by PBMCs at both the mRNA and protein levels was increased 2-fold (both P<0.05) in patients with acute MI compared with the two control groups. Notably, MMP2 was not expressed by PBMCs. Superarray screening revealed that PBMCs not only expressed MMPs, TIMPs (tissue inhibitors of metalloproteinases) and matrix proteins, but also served as an important source of cell adhesion molecules, inflammatory cytokines and growth factors. A total of 42 genes were differentially expressed in patients with acute MI compared with controls. Expression of selected genes was confirmed by real-time PCR. In conclusion, PBMCs constitute a key cellular source for elevated plasma MMP9, but not for MMP2. PBMCs also contribute to systemic and regional inflammation and matrix remodelling in acute MI.

An electrophoretic method for the detection of chymotrypsin and trypsin activity directly in whole blood

In biomedical research and clinical diagnostics, it is a major challenge to measure disease-related degradative enzyme activity directly in whole blood. Present techniques for assaying degradative enzyme activity require sample preparation, which makes the assays time-consuming and costly. This study now describes a simple and rapid electrophoretic method that allows detection of degradative enzyme activity directly in whole blood using charge-changing fluorescent peptide substrates. Charge-changing substrates eliminate the need for sample preparation by producing positively charged cleavage fragments that can be readily separated from the oppositely charged fluorescent substrate and blood components by electrophoresis. Two peptide substrates have been developed for pancreatic alpha-chymotrypsin and trypsin. For the first substrate, a detection limit of 3 ng for both alpha-chymotrypsin and trypsin was achieved in whole rat blood using a 4% agarose gel. This substrate had minimal cross-reactivity with the trypsin-like proteases thrombin, plasmin, and kallikrein. For the second substrate (trypsin-specific), a detection limit of about 10-20 pg was achieved using thinner higher resolution 20 and 25% polyacrylamide gels. Thus, the new charge changing peptide substrates enable a simple electrophoretic assay format for the measurement of degradative enzyme activity, which is an important step toward the development of novel point-of-care diagnostics.

Interleukin-6 release after carotid artery stenting and periprocedural new ischemic lesions

Carotid artery stenting (CAS) is currently a standard procedure to treat severe carotid artery stenosis. This procedure causes mechanical plaque rupture, potentially releasing soluble factors into the circulating blood. The purpose of this study is to clarify whether inflammation factors are released from an atherosclerotic plaque after CAS and whether local release of inflammation factors is associated with periprocedural new ischemic lesions. The study consisted of 35 patients with 40 severely stenotic carotid arteries who underwent CAS. Blood samples were obtained from the aorta before the procedure and from the carotid plaque site just after the procedure. Blood levels of interleukin-6 (IL-6), interleukin-18, matrix metalloproteinase (MMP)-2, and tissue inhibitor of MMP-1 were determined. Diffusion-weighted magnetic resonance imaging was performed before and after the procedure. Among inflammatory markers, IL-6 levels markedly increased at the plaque site in comparison to those at the aorta (P<0.001). The IL-6 levels in the local samples were significantly higher in symptomatic lesions than those in asymptomatic lesions. More importantly, higher local IL-6 levels were associated with the appearance of new ischemic lesions (P=0.003). The association remained significant (P=0.030) after controlling for potential risk factors for CAS. Association of local IL-6 levels and periprocedural new ischemic lesions suggests that massive release from the plaque and entry into the cerebral circulation of IL-6 might be one of important factors on periprocedural complications related to CAS.

Expression of EMMPRIN (CD147) on circulating platelets in vivo

BACKGROUND AND OBJECTIVES

EMMPRIN (CD147) is a matrix metalloproteinase inducer present on leukocytes and recently identified on platelets in vitro. We examined platelet CD147 expression in vivo and in correlation with markers of platelet activation and coronary artery disease (CAD).

PATIENTS/METHODS

This prospective observational study involved 70 subjects (55 patients with CAD and 15 controls). Platelet CD62P expression, PAC-1 expression, platelet-leukocyte aggregates and CD147 (both platelet and leukocyte) expression were assessed by flow cytometry, and soluble CD62P expression was assessed by enzyme-linked immunosorbent assay. A full blood count and high-sensitivity C-reactive protein test were performed.

RESULTS

CD147 was expressed on 20.45% +/- 1.63% (mean +/- standard error of the mean) of circulating platelets, whereas CD62P and PAC-1 were expressed on 0.87% +/- 0.12% and 0.90% +/- 0.27% of platelets, respectively. Platelet CD147 expression correlated with CD62P expression (r = 0.359, P = 0.002), PAC-1 expression (r = 0.428, P < 0.001), leukocyte CD147 expression (monocyte, r = 0.416, P = 0.001; granulocyte, r = 0.434, P < 0.001), C-reactive protein level and neutrophil/lymphocyte ratio (NLR). CAD patients had significantly higher CD147 mean fluorescence intensity than controls on circulating platelets (2.41 +/- 0.14 vs. 2.87 +/- 0.09, P = 0.014), monocytes (8.57 +/- 1.20 vs. 12.3 +/- 0.57, P = 0.006) and granulocytes (4.30 +/- 0.65 vs. 6.50 +/- 0.34, P = 0.005). Age adjustment eliminated the association between platelet CD147 expression and CAD, but the association between leukocyte CD147 expression and CAD persisted. According to multivariate analysis, the independent predictors of platelet CD147 expression were monocyte CD147 expression, NLR and age.

CONCLUSIONS

Platelet CD147 expression is evident in vivo and correlates moderately with traditional platelet activation markers and leukocyte CD147 expression. Platelet CD147 expression shows a stronger association with age, and leukocyte CD147 expression a stronger association with clinical CAD, suggesting differences in the regulation of platelet and leukocyte CD147 expression in vivo.

Association of circulating matrix metalloproteinases with carotid artery characteristics: the Atherosclerosis Risk in Communities Carotid MRI Study

OBJECTIVE

To examine the relationship of plasma levels of matrix metalloproteinases (MMPs) and tissue inhibitor of metalloproteinase 1 (TIMP-1) with carotid artery characteristics measured by MRI in a cross-sectional investigation among Atherosclerosis Risk in Communities Carotid MRI Study participants.

METHODS AND RESULTS

A stratified random sample was recruited based on intima-media thickness from a previous ultrasonographic examination. A high-resolution gadolinium-enhanced MRI examination of the carotid artery was performed from 2004 to 2005 on 1901 Atherosclerosis Risk in Communities cohort participants. Multiple carotid wall characteristics, including wall thickness, lumen area, calcium area, lipid core, and fibrous cap measures, were evaluated for associations with plasma MMPs 1, 2, 3, 7, 8, and 9 and TIMP-1. Plasma MMPs 1, 3, and 7 were significantly higher among participants in the high intima-media thickness group compared with those in the low intima-media thickness group. The normalized wall index was independently associated with MMPs 3 and 7 and TIMP-1. MMP-7 was positively associated with carotid calcification. The mean fibrous cap thickness was significantly higher in individuals with elevated TIMP-1 levels. In addition, TIMP-1 was positively associated with measures of lipid core.

CONCLUSION

Circulating levels of specific MMPs and TIMP-1 were associated with carotid wall remodeling and structural changes related to plaque burden in elderly participants.

MMP-9 inhibition by ACE inhibitor reduces oxidized LDL-mediated foam-cell formation

AIM

Angiotensin-converting enzyme inhibitors (ACEIs) have been shown to block matrix metalloproteinase (MMP)-9 activity, which plays a role in atherogenesis. MMP-9 activity of macrophages is increased during foam cell formation. To investigate the contribution of ACEIs to foam cell formation, we studied the effects of an ACEI, imidaprilat, on THP-1 macrophages and the underlying molecular mechanisms in vitro.

METHODS AND RESULTS

Pre-treatment of THP-1 macrophages with imidaprilat (100 nmol/L, 4 hours) significantly decreased foam cell formation induced by oxidized LDL (OxLDL). Imidaprilat reduced the protein level of MMP-9 in THP-1 macrophages and attenuated OxLDL-induced MMP-9 activity in the culture supernatants. Indeed, pretreatment of THP-1 macrophages with an MMP-2/9 inhibitor (20 micromol/L, 4 hours) attenuated OxLDL-induced foam-cell formation. Imidaprilat or the MMP-2/9 inhibitor blocked OxLDL-induced expressions of LOX-1 and scavenger receptor-A (SR-A), but not that of CD36, in THP-1 macrophages. In addition, OxLDL-induced activation of p38 mitogen-activated protein kinase (MAPK) and ERK, but not JNK, was blunted by imidaprilat or the MMP-2/9 inhibitor. Finally, siRNA against MMP-9 inhibited foam cell formation as well as lipid accumulation in THP-1 macrophages.

CONCLUSION

These findings suggest that imidaprilat reduces OxLDL-triggered foam-cell formation in THP-1 macrophages via modulation of MMP-9 activity and may indicate a novel antiinflamma-tory mechanism of imidaprilat in atherogenesis.

Matrix metalloproteinase-2 predicts mortality in patients with acute coronary syndrome

The aim of the present study was to investigate the predictive value of MMP (matrix metalloproteinase)-2, MMP-3 and MMP-9 levels in patients with acute coronary syndrome for death, readmission with HF (heart failure) or recurrent MI (myocardial infarction) and to compare them with established markers, NT-proBNP (N-terminal pro-B-type natriuretic peptide) and the GRACE (Global Registry of Acute Coronary Events) score. A single blood test was taken 4 days after admission in 1024 consecutive patients with acute MI with end points observed over 519 (134–1059) days [value is median (range)]. MMP-2 and MMP-3 were increased in patients who died (n=111) compared with survivors (P<0.006 and P=0.01 respectively), but were similar in patients with HF (n=106) or MI (n=138). MMP-9 levels were similar across study end points. Using Cox proportional hazards modelling, MMP-2 demonstrated an independent prediction of death [HR (hazard ratio) 6.60, P=0.001], along with NT-proBNP (HR 4.62, P<0.001) and the GRACE score (HR 1.03, P<0.001), but MMP-3, MMP-9 or log10-troponin I did not. For 1 year mortality, the areas under the receiver operating characteristic curves were 0.60 and 0.58 for MMP-2 and MMP-3 respectively, compared with 0.82 for NT-proBNP and 0.84 for the GRACE score (all P<0.001). Kaplan–Meier analysis revealed that MMP-2 levels in the top quartile were associated with higher mortality rates (log rank 12.49, P=0.006). On univariate analysis, MMP-2 and MMP-3 had a weak association with HF readmission, which was lost after adjustment for clinical factors. None of the MMPs tested predicted MI. In conclusion, this is the first single centre study that identifies MMP2 as an independent predictor of all-cause mortality post-ACS (acute coronary syndrome); however, NT-proBNP and the GRACE score are superior for risk stratification in this cohort.

Correlation of plasma MMP-1 and TIMP-1 levels and the colonic mucosa expressions in patients with ulcerative colitis

Background. Both plasma and mucosal levels of matrix metalloproteinase-1 (MMP-1) and tissue inhibitor of metalloproteinase-1 (TIMP-1) have been shown to be independently correlated with ulcerative colitis (UC), but their relationship with each other and to disease severity remains unclear. This study aims to evaluate the relationship between colonic mucosal and plasma levels of MMP-1 and TIMP-1 with each other and with the severity of ulcerative colitis (UC). Methods. Colonic mucosal lesions and venous blood samples were collected from 30 patients with UC and 15 normal subjects. Real-time reverse transcription-PCR and immunohistochemistry were used to determine colonic mucosal MMP-1 and TIMP-1 expression; ELISA was used to measure plasma levels of MMP-1 and TIMP-1. Results. Expression of colonic mucosal and plasma MMP-1 and TIMP-1 in patients with UC was significantly higher than that of controls (P < .05), and was positively correlated with disease severity (P < .05). Plasma MMP-1 and TIMP-1 levels were well correlated with their corresponding expression in colonic mucosa (P < .05, r = 0.805 and 0.908). Conclusion. Plasma MMP-1 and TIMP-1 levels reflect their colonic mucosal expression to some extent in patients with UC. Plasma MMP-1 and TIMP-1, in particular, demonstrate the potential to become biomarkers to clinically diagnose UC, predict its severity, and guide further therapy.

Serum levels of matrix metalloproteinases -1,-2,-3 and -9 in thoracic aortic diseases and acute myocardial ischemia

Background

Matrix metalloproteinases (MMPs) constitute a family of zinc-dependent proteases (endopeptidases) whose catalytic action is the degradation of the extracellular matrix components. In addition, they play the major role in the degradation of collagen and in the process of tissue remodeling. The present clinical study investigated blood serum levels of metalloproteinases- 1, -2, -3 and -9 in patients with acute and chronic aortic dissection, thoracic aortic aneurysm and acute myocardial ischemia compared to healthy individuals.

Methods

The blood serum levels of MMP-1, -2, -3 and -9 were calculated in 31 patients with acute aortic dissection, 18 patients with chronic aortic dissection, 18 patients with aortic aneurysm and in 13 patients with acute myocardial ischemia, as well as in 15 healthy individuals who served as the control group. Serum MMP levels were measured by using an ELISA technique.

Results

There were significantly higher levels of MMP-3 in patients with acute myocardial ischemia as compared to acute aortic dissection (17.33 ± 2.03 ng/ml versus 12.92 ± 1.01 ng/ml, p < 0.05). Significantly lower levels of MMP-1 were found in healthy controls compared to all groups of patients (1.1 ± 0.38 ng/ml versus 2.97 ± 0.68 in acute aortic dissection, 3.09 ± 0.98 in chronic dissection, 3.16 ± 0.51 in thoracic aortic aneurysm and 4.58 ± 1.04 in acute myocardial ischemia, p < 0.05). Higher levels of MMP-1 and MMP-3 were detected on males. There was a positive correlation with increasing age (r = 0.38, p < 0.05). In patients operated for acute type A aortic dissection, the levels of MMP-1, MMP-3 and MMP-9 increased immediately after surgery, while the levels of MMP-2 decrease. At 24 hours postoperatively, levels of MMP -1, -2 and -9 are almost equal to the preoperative ones.

Conclusion

Measurement of serum MMP levels in thoracic aortic disease and acute myocardial ischemia is a simple and relatively rapid laboratory test that could be used as a biochemical indicator of aortic disease or acute myocardial ischemia, when evaluated in combination with imaging techniques.

Broad regulation of matrix and adhesion molecules in THP-1 human macrophages by nitroglycerin

Although nitroglycerin (NTG) is effective for the acute relief in coronary ischemic diseases, its long-term benefits in mortality and morbidity have been questioned. The possibility has been raised that NTG may increase the activity of matrix metalloproteinases (MMP), which could lead to disruption and dislodging of atherosclerotic plaques. This study examined the broad effects of acute NTG exposure on the expression and activity of genes encoding MMP-9, as well as an array of ECM and adhesion molecules in THP-1 human macrophages. Gene array studies identified that while NTG exposure (100microM, 48h) did not significantly increase MMP-9 gene expression, genes encoding testican-1, integrin alpha-1, thrombospondin-3, fibronectin-1 and MMP-26 were significantly down-regulated. On the other hand, genes encoding catenin beta-1 and vascular cell-adhesion molecule-1 were up-regulated. Real-time PCR studies confirmed significant down-regulation of testican-1 gene expression, but its protein expression was not significantly altered. NTG exposure, caused a significant increase in total MMP-9 protein expression (1.96-fold) and active MMP-9 (3.7-fold) concentrations. Recombinant MMP-9 was significantly activated by NTG and its dinitrate metabolites, indicating post-translation modification of this protein by organic nitrates. These results indicate that NTG exposure could broadly affect the gene expression and activity of proteases that govern the ECM cascade, thereby potentially altering atherosclerotic plaque stability.

Matrix metalloproteinase therapy in heart failure

Milestones in the progression to heart failure following myocardial infarction (MI) are changes in left ventricular (LV) geometry and function, termed post-MI remodeling. Critical to this adverse remodeling process are changes in the expression, synthesis, and degradation of myocardial extracellular matrix (ECM) proteins. The myocardial ECM is not a passive entity but a complex and dynamic microenvironment that represents an important structural and signaling system within the myocardium. In particular, basic and clinical studies have provided conclusive evidence that abnormal and persistent activation of the ECM degradation pathway, notably through the matrix metalloproteinases (MMPs), contribute to adverse post-MI remodeling. This review examines recent clinical studies that provide further support to the hypothesis that a specific portfolio of MMPs are diagnostic and likely contributory to LV remodeling and the progression to heart failure after MI. Future translational and clinical research focused on the molecular and cellular mechanisms regulating ECM structure and function likely will contribute to an improved understanding of post-MI LV remodeling and yield novel therapeutic targets.

Cross-sectional relations of multiple biomarkers representing distinct biological pathways to plasma markers of collagen metabolism in the community

OBJECTIVE

Hyperhomocysteinemia, neurohormonal activation, inflammation and altered fibrinolysis have been linked to atherothrombosis as well as to myocardial fibrosis and heart failure. Hence, we related a panel of biomarkers representing these pathways to plasma markers of collagen metabolism in a large community-based sample.

METHODS

We related nine biomarkers representing select biologic pathways (independent variables: C-reactive protein, B-type natriuretic peptide, N-terminal proatrial natriuretic peptide, aldosterone, renin, fibrinogen, D-dimer, plasminogen activator inhibitor-1 and homocysteine) to three plasma markers of collagen turnover [dependent variables, separate models for each: aminoterminal propeptide of type III collagen, tissue inhibitor of metalloproteinases-1 and matrix metalloproteinase-9 (present versus absent)] in 921 Framingham Heart study participants (mean age 57 years; 58% women). Participants were separated a priori into those with left ventricular end-diastolic dimensions and wall thickness below sex-specific median values (referent group) and either measure at least 90th sex-specific percentile ('remodeled' group). We used stepwise multivariable regression analysis adjusting for cardiovascular risk factors to relate the panel of systemic biomarkers to the three biomarkers of collagen metabolism.

RESULTS

Plasma homocysteine was positively related to all three markers of collagen metabolism in the remodeled group and to aminoterminal propeptide of type III collagen and tissue inhibitor of metalloproteinases-1 in the referent group. Plasminogen activator inhibitor-1 was positively related to aminoterminal propeptide of type III collagen and tissue inhibitor of metalloproteinases-1 in both groups, whereas the natriuretic peptides were associated positively with these collagen markers in the referent group.

CONCLUSION

In our large community-based sample, plasma homocysteine and plasminogen activator inhibitor-1 were positively related to circulating collagen biomarkers, consistent with experimental studies implicating these pathways in cardiovascular collagen turnover.

Influence of conjugated linoleic acids on functional properties of vascular cells

Conjugated linoleic acids (CLA) are biologically highly active lipid compounds that inhibit the development of atherosclerotic plaques in experimental animals. The underlying mechanisms of action, however, are only poorly understood. Since cell-culture experiments are appropriate to provide a detailed view into the mechanisms of action of a compound, the present review summarises results fromin vitrostudies dealing with the effects of CLA isomers and CLA mixtures on functional properties of cells of the vascular wall, such as endothelial cells, smooth muscle cells and monocyte-derived macrophages, which are amongst the major cells contributing to atherosclerotic lesion development. Based on these studies, it can be concluded that CLA exert several beneficial actions in cells of the vascular wall through the activation of nuclear PPAR. These actions of CLA, which may, at least partially, explain the inhibition of atherogenesis by dietary CLA, include modulation of vasoactive mediator release from endothelial cells, inhibition of inflammatory and fibrotic processes in activated smooth muscle cells, abrogation of inflammatory responses in activated macrophages, and reduction of cholesterol accumulation in macrophage-derived foam cells.

Quick identification of acute chest pain patients study (QICS)

Background

Patients with acute chest pain are often referred to the emergency ward and extensively investigated. Investigations are costly and could induce unnecessary complications, especially with invasive diagnostics. Nevertheless, chest pain patients have high mortalities. Fast identification of high-risk patients is crucial. Therefore several strategies have been developed including specific symptoms, signs, laboratory measurements, and imaging.

Methods/Design

The Quick Identification of acute Chest pain Study (QICS) will investigate whether a combined use of specific symptoms and signs, electrocardiography, routine and new laboratory measures, adjunctive imaging including electron beam (EBT) computed tomography (CT) and contrast multislice CT (MSCT) will have a high diagnostic yield for patients with acute chest pain. All patients will be investigated according a standardized protocol in the Emergency Department. Serum and plasma will be frozen for future analysis for a wide range of biomarkers at a later time point. The primary endpoint is the safe recognition of low-risk chest pain patients directly at presentation. Secondary endpoint is the identification of a wide range of sensitive predictive clinical markers, chemical biomarkers and radiological markers in acute chest pain patients. Chemical biomarkers will be compared to quantitative CT measurements of coronary atherosclerosis as a surrogate endpoint. Chemical biomarkers will also be compared in head to head comparison and for their additional value.

Discussion

This will be a very extensive investigation of a wide range of risk predictors in acute chest pain patients. New reliable fast and cheap diagnostic algorithm resulting from the test results might improve chest pain patients' prognosis, and reduce unnecessary costs and diagnostic complications.

Potential implications of matrix metalloproteinase-9 in assessment and treatment of coronary artery disease

BACKGROUND

Matrix metalloproteinase (MMP)-9, a member of the MMP superfamily is consistently implicated in the pathophysiology of atherosclerosis and plaque rupture, the most common mechanism responsible for acute coronary syndrome (ACS).

AIM

To summarize the role of MMP-9 in atherosclerosis and its potential implications in assessment and treatment of coronary artery disease (CAD).

METHODS

We reviewed the PubMed database for relevant data regarding the role of MMP-9 in the pathophysiology of atherosclerosis. In the light of these data, we postulate potential implications of MMP-9 in the management and treatment of CAD.

RESULTS AND CONCLUSIONS

Existing data strongly support the role of MMP-9 in plaque destabilization and rupture. Based on the current knowledge, MMP-9 can potentially serve as a diagnostic biomarker in ACS and a prognostic biomarker in ACS and chronic CAD patients. MMP-9 is reduced by therapies that are associated with favourable outcome in atherosclerosis and thus may serve as a surrogate biomarker of treatment efficacy. However, large morbidity and mortality trials are still required to confirm that MMP-9 reduction is associated with improved outcome independent of the traditional risk factors (i.e. low-density lipoprotein cholesterol). Given its role in plaque rupture, inhibition of MMP-9 may promote plaque stabilization and consequently reduce cardiovascular events. Yet, the efficacy and safety of MMPs inhibitors should be first studied in preclinical models of atherosclerosis.