Time dependent alterations of serum matrix metalloproteinase-1 and metalloproteinase-1 tissue inhibitor after successful reperfusion of acute myocardial infarction

The Effects of Chronic Immunosuppressive Treatment on Morphological Changes in Cardiac Tissue and the Balance between Matrix Metalloproteinases (MMP-2 and MMP-9) and Their Inhibitors in the Rat Heart

Using different three-drug immunosuppressive treatment regimens in a rat model, we aimed to determine the effects of long-term therapy on metalloproteinase-2 and metalloproteinase-9 activity and the expression of their inhibitors, as well as to assess the morphology of the animals' cardiac tissue. Our results suggest that chronic use of immunosuppressive drugs disrupts the balance between the activity of MMPs and TIMPs. Depending on the type of drug regimen used, this leads to abnormalities in the cardiac structure, collagen fiber accumulation, or cardiomyocyte hypertrophy. The information obtained in the present study allows us to conclude that the chronic treatment of rats with the most common clinical immunosuppressive regimens may contribute to abnormalities in the myocardial structure and function. The results presented in this study may serve as a prelude to more in-depth analyses and additional research into the optimal selection of an immunosuppressive treatment with the lowest possible risk of cardiovascular complications for patients receiving organ transplants.

Bioresponsive Cytokine Delivery Responding to Matrix Metalloproteinases

Cytokines are regulated in acute and chronic inflammation, including rheumatoid arthritis (RA) and myocardial infarction (MI). However, the dynamic windows within which cytokine activity/inhibition is desirable in RA and MI change timely and locally during the disease. Therefore, traditional, static delivery regimens are unlikely to meet the idiosyncrasy of these highly dynamic pathophysiological and individual processes. Responsive delivery systems and biomaterials, sensing surrogate markers of inflammation (i.e., matrix metalloproteinases - MMPs) and answering with drug release, may present drug activity at the right time, manner, and place. This article discusses MMPs as surrogate markers for disease activity in RA and MI to clock drug discharge to MMP concentration profiles from MMP-responsive drug delivery systems and biomaterials.

The Effect of Calcineurin Inhibitors on MMPs Activity in Heart and Their Side Effects-A Review of Literature

This review focuses on the role of metalloproteinases in the pathogenesis of myocardial injury in various disease entities. It reveals how the expression and serum levels of metalloproteinases and their inhibitors change in many disease states. At the same time, the study offers a review of the impact of immunosuppressive treatment on this relationship. Modern immunosuppressive treatment is based mainly on the use of calcineurin inhibitors, including cyclosporine A and tacrolimus. The use of these drugs may carry a number of side effects, specifically to the cardiovascular system. The scale and degree of long-term influence on the organism remains unclear, but a significant risk of complications for transplant recipients who take immunosuppressive drugs as part of their daily treatment is to be expected. Therefore, the knowledge on this subject should be expanded and the negative effects of post-transplant therapy minimized. Immunosuppressive therapy plays an important role in the expression and activation of tissue metalloproteinases and their specific inhibitors, which leads to many tissue changes. The presented study is a collection of research results on the effects of calcineurin inhibitors on the heart, with particular emphasis placed on the participation of MMP-2 and MMP-9. It is also an analysis of the effects of specific heart diseases on myocardial remodeling through inductive or inhibitory effects on matrix metalloproteinases and their inhibitors.

Don't go breakin' my heart: cardioprotective alterations to the mechanical and structural properties of reperfused myocardium during post-infarction inflammation

Myocardial infarctions (MIs) kickstart an intense inflammatory response resulting in extracellular matrix (ECM) degradation, wall thinning, and chamber dilation that leaves the heart susceptible to rupture. Reperfusion therapy is one of the most effective strategies for limiting adverse effects of MIs, but is a challenge to administer in a timely manner. Late reperfusion therapy (LRT; 3 + hours post-MI) does not limit infarct size, but does reduce incidences of post-MI rupture and improves long-term patient outcomes. Foundational studies employing LRT in the mid-twentieth century revealed beneficial reductions in infarct expansion, aneurysm formation, and left ventricle dysfunction. The mechanism by which LRT acts, however, is undefined. Structural analyses, relying largely on one-dimensional estimates of ECM composition, have found few differences in collagen content between LRT and permanently occluded animal models when using homogeneous samples from infarct cores. Uniaxial testing, on the other hand, revealed slight reductions in stiffness early in inflammation, followed soon after by an enhanced resistance to failure for cases of LRT. The use of one-dimensional estimates of ECM organization and gross mechanical function have resulted in a poor understanding of the infarct's spatially variable mechanical and structural anisotropy. To resolve these gaps in literature, future work employing full-field mechanical, structural, and cellular analyses is needed to better define the spatiotemporal post-MI alterations occurring during the inflammatory phase of healing and how they are impacted following reperfusion therapy. In turn, these studies may reveal how LRT affects the likelihood of rupture and inspire novel approaches to guide scar formation.

The Role of Matrix Proteins in Cardiac Pathology

The extracellular matrix (ECM) and ECM-regulatory proteins mediate structural and cell-cell interactions that are crucial for embryonic cardiac development and postnatal homeostasis, as well as organ remodeling and repair in response to injury. These proteins possess a broad functionality that is regulated by multiple structural domains and dependent on their ability to interact with extracellular substrates and/or cell surface receptors. Several different cell types (cardiomyocytes, fibroblasts, endothelial and inflammatory cells) within the myocardium elaborate ECM proteins, and their role in cardiovascular (patho)physiology has been increasingly recognized. This has stimulated robust research dissecting the ECM protein function in human health and disease and replicating the genetic proof-of-principle. This review summarizes recent developments regarding the contribution of ECM to cardiovascular disease. The clear importance of this heterogeneous group of proteins in attenuating maladaptive repair responses provides an impetus for further investigation into these proteins as potential pharmacological targets in cardiac diseases and beyond.

Plasma matrix metalloproteinases (MMPs) and tissue inhibitors of MMPs and aging and lifelong exercise adaptations in ventricular and arterial stiffness

The age-associated increase in cardiac and central arterial stiffness is attenuated with lifelong (>25 years) endurance exercise in a dose-dependent manner. Remodelling of the extracellular matrix of cardiovascular structures may underpin these lifelong exercise adaptations in structural stiffness. The primary aim was to examine whether matrix metalloproteinases (MMPs) and tissue inhibitors of matrix metalloproteinases (TIMPs) levels are associated with aging and lifelong exercise-related changes in cardiac and central arterial stiffness. Plasma MMPs and TIMPs, left ventricular (LV) (LV stiffness constant) and central arterial stiffness (pulse wave velocity) were examined in healthy adults stratified into five groups based on age and lifelong weekly exercise frequency: (1) young sedentary adults (28-50 years), and older adults (>60 years) who had performed either: (a) sedentary (0-1 sessions/week), (b) casual (2-3 sessions/week), (c) committed (4-5 sessions/week) or (d) athletic (≥6 sessions/week) frequency of exercise. MMP-1 was significantly lower in young compared to older sedentary (p = 0.049). Except for TIMP-2 (p = 0.018 versus committed) and the ratio of MMP-2/TIMP-4 (p = 0.047 versus committed), MMP and TIMP expression was not significantly different in lifelong exercise groups (≥casual) compared to the older sedentary group. MMP-1, -3 had a weak positive relationship with central PWV (r = 0.17-0.25, p ≤ 0.050) but there were no significant relationships between MMPs or TIMPs and LV stiffness constant (p ≥ 0.148). In conclusion, there was not a clear or consistent difference in plasma MMPs and TIMPs with lifelong exercise dose despite exhibiting lower cardiovascular stiffness at the highest exercise levels.

Matrix Metalloproteinases in Myocardial Infarction and Heart Failure

Cardiovascular disease is the leading cause of death, accounting for 600,000 deaths each year in the United States. In addition, heart failure accounts for 37% of health care spending. Matrix metalloproteinases (MMPs) increase after myocardial infarction (MI) and correlate with left ventricular dysfunction in heart failure patients. MMPs regulate the remodeling process by facilitating extracellular matrix turnover and inflammatory signaling. Due to the critical role MMPs play during cardiac remodeling, there is a need to better understand the pathophysiological mechanism of MMPs, including the biological function of the downstream products of MMP proteolysis. Future studies developing new therapeutic targets that inhibit specific MMP actions to limit the development of heart failure post-MI are warranted. This chapter focuses on the role of MMPs post-MI, the efficiency of MMPs as biomarkers for MI or heart failure, and the future of MMPs and their cleavage products as targets for prevention of post-MI heart failure.

Matrix metalloproteinases in coronary artery disease

Matrix metalloproteinases (MMP) are a family of zinc-containing endoproteinases that degrade extracellular matrix (ECM) components. MMP have important roles in the development, physiology and pathology of cardiovascular system. Metalloproteases also play key roles in adverse cardiovascular remodeling, atherosclerotic plaque formation and plaque instability, vascular smooth muscle cell (SMC) migration and restenosis that lead to coronary artery disease (CAD), and progressive heart failure. The study of MMP in developing animal model cardiovascular systems has been helpful in deciphering numerous pathologic conditions in humans. Increased peripheral blood MMP-2 and MMP-9 in acute coronary syndrome (ACS) may be useful as noninvasive tests for detection of plaque vulnerability. MMP function can be modulated by certain pharmacological drugs that can be exploited for treatment of ACS. CAD is a polygenic disease and hundreds of genes contribute toward its predisposition. A large number of sequence variations in MMP genes have been identified. Case-control association studies have highlighted their potential association with CAD and its clinical manifestations. Although results thus far are inconsistent, meta-analysis has demonstrated that MMP-3 Glu45Lys and MMP-9 1562C/T gene polymorphisms were associated with CAD risk.

Interleukin-33, matrix metalloproteinase-9, and tissue inhibitor [corrected] of matrix metalloproteinase-1 in myocardial infarction

BACKGROUND/AIMS

Acute coronary syndrome (ACS) is characterized by increased inflammatory processes and endothelial activation. We investigated the association between ACS and inflammatory mediators and matrix-degrading enzymes.

METHODS

We prospectively enrolled 55 consecutive patients with ACS: 25 with unstable angina (UA) and 30 with non-ST elevated myocardial infarction (NSTEMI). For comparison, 25 age- and sex-matched subjects with no significant coronary artery stenosis were included as the control group. Peripheral serum levels of interleukin (IL)-33, matrix metalloproteinase (MMP)-9, tissue inhibitor of MMP-1, and C-reactive protein (CRP) were measured on admission, and at 12, 24, 48, and 72 hours after the initial evaluation.

RESULTS

Compared to serum levels in the control group, serum levels of IL-33 decreased in the NSTEMI group (p < 0.05), and levels of MMP-9 and tissue inhibitor of matrix metalloproteinase (TIMP)-1 increased in the UA group (p < 0.01, p < 0.05, respectively) and NSTEMI group (p < 0.05, p < 0.05, respectively). IL-33 levels were significantly lower on admission than at 12 hours after the initial evaluation (p < 0.05). IL-33 levels were negatively correlated with MMP-9 levels (r = -0.461, p < 0.05) and CRP levels (r = -0.441, p < 0.05).

CONCLUSIONS

Elevated levels of MMP-9, TIMP-1, and decreased levels of IL-33 play a role in the development and progression of ACS.

Matrix metalloproteinase inhibition protects CyPD knockout mice independently of RISK/mPTP signalling: a parallel pathway to protection

The mitochondrial permeability transition pore (mPTP) is widely accepted as an end-effector mechanism of conditioning protection against injurious ischaemia/reperfusion. However, death can be initiated in cells without pre-requisite mPTP opening, implicating alternate targets for ischaemia/reperfusion injury amelioration. Matrix metalloproteinases (MMP) are known to activate extrinsic apoptotic cascades and therefore we hypothesised that MMP activity represents an mPTP-independent target for augmented attenuation of ischaemia/reperfusion injury. In ex vivo and in vivo mouse hearts, we investigated whether the MMP inhibitor, ilomastat (0.25 μmol/l), administered upon reperfusion could engender protection in the absence of cyclophilin-D (CyPD), a modulator of mPTP opening, against injurious ischaemia/reperfusion. Ilomastat attenuated infarct size in wild-type (WT) animals [37 ± 2.8 to 22 ± 4.3 %, equivalent to ischaemic postconditioning (iPostC), used as positive control, 27 ± 2.1 %, p < 0.05]. Control CyPD knockout (KO) hearts had smaller infarcts than control WT (28 ± 4.2 %) and iPostC failed to confer additional protection, yet ilomastat significantly attenuated infarct size in KO hearts (11 ± 3.0 %, p < 0.001), and similar protection was also seen in isolated cardiomyocytes. Moreover, ilomastat, unlike the cyclophilin inhibitor cyclosporine-A, had no impact upon reactive oxygen species-mediated mPTP opening. While MMP inhibition was associated with increased Akt and ERK phosphorylation, neither Wortmannin nor PD98059 abrogated ilomastat-mediated protection. We demonstrate that MMP inhibition is cardioprotective, independent of Akt/ERK/CyPD/mPTP activity and is additive to the protection observed following inhibition of mPTP opening, indicative of a parallel pathway to protection in ischaemic/reperfused heart that may have clinical applicability in attenuating injury in acute coronary syndromes and deserve further investigation.

Imbalance between tissue inhibitor of metalloproteinase 1 and matrix metalloproteinase 9 after cardiopulmonary resuscitation

AIMS

This study aimed to determine whether (a) there was an imbalance between matrix metalloproteinase 9 (MMP-9) and tissue inhibitor of metalloproteinase 1 (TIMP-1) after cardiopulmonary resuscitation (CPR) in a canine model of prolonged ventricular fibrillation (VF); (b) with the duration of VF, the degree of the imbalance would be greater; and (c) there was a relationship between the level of MMP-9 or TIMP-1 and the cardiac function.

METHODS AND RESULTS

Ventricular fibrillation was electrically induced in 24 dogs. The animals were randomly divided into 3 groups (sham control, n = 8; 8-minute VF, n = 8; 12-minute VF, n = 8). Echocardiographic measurement and hemodynamic variables were recorded before VF and after return of spontaneous circulation. Tissue inhibitor of metalloproteinase 1 (TIMP-1) and MMP-9 were analyzed by Western blot and immunohistochemistry. Compared with sham controls, dogs under VF and CPR showed significantly decreased level of TIMP-1 (P < .001), and with the duration of VF, the level of TIMP-1 declined (P < .01). The level of MMP-9 did not achieve statistical significance in the 3 groups (P > .05); however, they were higher in VF and longer duration VF groups. The ratios of TIMP-1/MMP-9 were lower in VF groups (P < .05). There was a negative correlation between TIMP-1 and left atrium dimension and left ventricular diastolic dimensions (r = -0.83 and r = -0.96, respectively; P < .01) and a positive correlation between TIMP-1 and left ventricular ejection fraction (r = 0.85; P < .01).

CONCLUSIONS

There was an imbalance between TIMP-1 and MMP-9 after CPR. It may partly contribute to the postresuscitation cardiac dysfunction.

Myocardial remodeling: cellular and extracellular events and targets

The focus of this review is on translational studies utilizing large-animal models and clinical studies that provide fundamental insight into cellular and extracellular pathways contributing to post-myocardial infarction (MI) left ventricle (LV) remodeling. Specifically, both large-animal and clinical studies have examined the potential role of endogenous and exogenous stem cells to alter the course of LV remodeling. Interestingly, there have been alterations in LV remodeling with stem cell treatment despite a lack of long-term cell engraftment. The translation of the full potential of stem cell treatments to clinical studies has yet to be realized. The modulation of proteolytic pathways that contribute to the post-MI remodeling process has also been examined. On the basis of recent large-animal studies, there appears to be a relationship between stem cell treatment post-MI and the modification of proteolytic pathways, generating the hypothesis that stem cells leave an echo effect that moderates LV remodeling.

Increased serum levels of tissue inhibitor of metalloproteinase-1 in patients with acute myocardial infarction

It has been suggested that matrix-metalloproteinases (MMPs) and their inhibitors (tissue inhibitors of metalloproteinases (TIMPs) play a major role in the regulation of myocardial remodeling. Myocardial extracellular matrix (ECM) is highly susceptible to ischemic injury in acute myocardial infarction (AMI).We measured serum levels of TIMP-1 in the early hours of AMI to study the kinetics of these enzymes in an early ischemic phase.TIMP-1 was measured in 25 patients with AMI and 116 healthy controls. Blood samples were obtained during the first 12 hours after hospital admission. Left ventricular function (LVF) and hemodynamic data were collected during coronary intervention.TIMP-1 was significantly elevated in patients with AMI within the first hours compared to controls (P<0.05). No significant difference was observed between patients with preserved LVF and with impaired LVF. Elevated TIMP-1 levels did not correlate with increased levels of CK or CK-MB band during the first hours after AMI.Increased TIMP-1 can be detected within 12 hours in patients with AMI, suggesting early onset of remodeling. Elevation of TIMP-1 may be a surrogate marker for increased ECM-turnover. The prognostic relevance needs to be proved in long-term studies.

Matrix metalloproteinases and cardiovascular diseases

Matrix metalloproteinases (MMPs) are extracellular enzymes that are important in many physiologic and pathologic processes. Their activity is regulated mainly by tissue inhibitors of metalloproteinases (TIMPs). MMPs expression is related with the classical cardiovascular risk factors as well as with inflammation. They play a central role in atherosclerosis, plaque formation, platelet aggregation, acute coronary syndrome, restenosis, aortic aneurysms and peripheral vascular disease. Many studies have shown that commonly prescribed antihypertensive medications, glitazones and statins may influence MMPs activity. The aim of the review is to present literature data on the role of MMPs and their inhibitors in cardiovascular disease.

Plasma tissue inhibitor of metalloproteinase-1 and matrix metalloproteinase-9: novel indicators of left ventricular remodelling and prognosis after acute myocardial infarction

AIMS

Matrix metalloproteinase (MMP) activity is central to the development of left ventricular (LV) remodelling and dysfunction after acute myocardial infarction (AMI). We assessed the relationships with LV structure and function and outcome, of tissue inhibitors of metalloproteinase-1 (TIMP-1) and MMP-9, and compared with N-terminal pro-B-type natriuretic peptide (NTproBNP).

METHODS AND RESULTS

We studied 404 patients with AMI. Primary outcome measures were the associations of TIMP-1, MMP-9, and NTproBNP with death or heart failure, and with LV dimensions, function and remodelling (ΔLVEDV, change in LV end-diastolic volume between discharge and follow-up). Cut-off concentrations for prediction of death or heart failure were identified from receiver operator characteristic (ROC) curves. In multivariable analysis, TIMP-1 and NTproBNP had predictive value for LV ejection fraction pre-discharge (TIMP-1 P = 0.023; N-BNP P = 0.007) and at follow-up (TIMP-1 P = 0.001; N-BNP P = 0.003). MMP-9, TIMP-1, and NTproBNP correlated directly with LV volumes. MMP-9 (P = 0.005) and TIMP-1 (P = 0.036), but not NTproBNP, correlated with ΔLVEDV. For the combined endpoint of death or heart failure the area under the ROC curve was 0.640 for MMP-9, 0.799 for NTproBNP and 0.811 for TIMP-1. Patients with TIMP-1 > 135 ng/mL (P < 0.001) or NTproBNP >1472 fmol/mL (P < 0.001) had increased risk of endpoint. Consideration of both NTproBNP and TIMP-1 further improved risk stratification.

CONCLUSION

TIMP-1 and MMP-9 correlate with echocardiographic parameters of LV dysfunction and remodelling after AMI and may identify patients at risk of subsequent LV remodelling and adverse prognosis.

Inhibiting metalloproteases with PD 166793 in heart failure: impact on cardiac remodeling and beyond

Metalloproteinases (MMPs, also called matrixins) are extracellular proteolytic enzymes involved in the degradation of both matrix and nonmatrix proteins. Currently, 25 MMPs have been identified in humans, and the overexpression of one or more MMPs has been implicated in several pathologies, spanning from cancer to rheumathoid arthritis to cardiovascular disease. While research over the past 20 years has focused on understanding MMP biology and selectively inhibiting MMP activity, key issues that remain to be addressed include MMP roles in the context of normal versus pathological conditions and whether globally inhibiting MMPs improves or deteriorates overall organ function. In terms of cardiovascular disease, increased MMP expression has been demonstrated in the setting of myocardial ischemia, reperfusion injury, and during the progression to congestive heart failure. MMPs are also major contributors to the progression of atherosclerotic lesions. In this review, we focus on cardiovascular effects produced by PD 166793, a wide-broad spectrum MMP inhibitor, originally developed by Parke-Davis (now Pfizer). We will briefly review its structure, mechanism of action, and inhibitory capacity. Finally, we will illustrate the cardiac contexts, both in vivo and in vitro, in which PD166793 administration has proven beneficial.

Matrix metalloproteinase-1 and tissue inhibitors do not predict incident coronary artery disease in the atherosclerosis risk in communities (ARIC) study

Matrix metalloproteinases (MMPs) and tissue inhibitors of matrix metalloproteinases (TIMPs) are thought to be associated with coronary artery disease. The association of these markers with incident coronary artery disease has not been well described. Using a case-cohort design, we selected 216 individuals who had incident coronary artery disease (case group) and 225 individuals from a cohort random sample (comparison group) from participants enrolled in the Atherosclerosis Risk in Communities study. We measured plasma levels of MMP-1 and TIMP-1, traditional risk factors, and other markers of inflammation. We found no significant difference in TIMP-1 levels between the case group (827.8 +/- 23.8 ng/mL) and the comparison group (819.31 +/- 16.1 ng/mL) (P=0.77), and no significant difference in the frequency of MMP-1 levels that were dichotomized at the minimum detectable value of 1.7 ng/mL (P=0.49). In models adjusted for age, sex, race, body mass index, hypertension, diabetes, total cholesterol, high-density lipoprotein cholesterol, triglycerides, fibrinogen, von Willebrand factor, and white blood cell count, the hazard-rate ratio for incident coronary artery disease was 1.14 (95% confidence interval, 0.63-2.04; P=0.67) for individuals whose TIMP-1 levels were above, versus at or below the mean, and 1.17 (95% confidence interval, 0.63-2.19; P=0.62) for individuals whose MMP-1 levels were above 1.7 ng/mL. We conclude that TIMP-1 and MMP-1 levels in plasma were not predictive of incident coronary artery disease in a case-cohort random sample of the Atherosclerosis Risk in Communities study, a population study of asymptomatic middle-aged adults who had no prevalent atherosclerosis upon enrollment.

Serum interferon-gamma-inducible protein 10 level was increased in myocardial infarction patients, and negatively correlated with infarct size

OBJECTIVES

We examined the serum levels of interferon-gamma-inducible protein 10 (IP-10), an inflammation-induced chemokine, in acute myocardial infarction (AMI).

DESIGN AND METHODS

The subjects were 33 AMI patients, 20 stable angina pectoris patients (AP) and 20 normal subjects. In AMI patients, blood samples were collected before percutaneous coronary intervention (PCI) and on days 3, 7 and 28.

RESULTS

Patients with AMI showed significantly higher serum IP-10 levels (137.5+/-79.8 pg/mL) than control subjects (91.2+/-40.1 pg/mL) and patients with AP (93.3+/-41.1 pg/mL). The serum IP-10 level before PCI was negatively correlated with infarct size, as indicated by cumulative release of creatine kinase (CK) and peak CK and its isoenzyme CK-MB. Stepwise multiple regression analysis revealed that the serum IP-10 level before PCI was an independent predictor of cumulative CK release.

CONCLUSIONS

The serum IP-10 level was increased in AMI, and a higher level of serum IP-10 before PCI may be informative regarding infarct size.

Myocardial Matrix Remodeling and the Matrix Metalloproteinases: Influence on Cardiac Form and Function

It is now becoming apparent that dynamic changes occur within the interstitium that directly contribute to adverse myocardial remodeling following myocardial infarction (MI), with hypertensive heart disease and with intrinsic myocardial disease such as cardiomyopathy. Furthermore, a family of matrix proteases, the matrix metalloproteinases (MMPs) and the tissue inhibitors of MMPs (TIMPs), has been recognized to play an important role in matrix remodeling in these cardiac disease states. The purpose of this review is fivefold: 1) to examine and redefine the myocardial matrix as a critical and dynamic entity with respect to the remodeling process encountered with MI, hypertension, or cardiomyopathic disease; 2) present the remarkable progress that has been made with respect to MMP/TIMP biology and how it relates to myocardial matrix remodeling; 3) to evaluate critical translational/clinical studies that have provided a cause-effect relationship between alterations in MMP/TIMP regulation and myocardial matrix remodeling; 4) to provide a critical review and analysis of current diagnostic, prognostic, and pharmacological approaches that utilized our basic understanding of MMP/TIMPs in the context of cardiac disease; and 5) most importantly, to dispel the historical belief that the myocardial matrix is a passive structure and supplant this belief that the regulation of matrix protease pathways such as the MMPs and TIMPs will likely yield a new avenue of diagnostic and therapeutic strategies for myocardial remodeling and the progression to heart failure.

Matrix metalloproteinases and myocardial infarction

Acute myocardial infarction (AMI) is currently one of the most important health problems in many countries around the world. Following AMI, many cytokines and proteolytic enzymes are released. Among these, matrix metalloproteinases (MMPs) are important proteolytic enzymes that lead to degradation of the extracellular matrix and to changes in cardiomyocytes in both infarcted and noninfarcted myocardium. This process is known as cardiac remodelling. It has been demonstrated that more than one type of MMP is present in the circulation after cardiomyocyte injury. A number of studies have demonstrated the correlations between these MMP levels and the severity of a coronary lesion, the progression of left ventricular dimension and the survival rate following AMI in both animal and human studies. MMPs have also been proposed as a possible novel prognostic indicator for myocardial infarction patients. Although the use of MMP inhibitors to improve cardiac outcome in AMI patients has been investigated, discrepancies in the results from those studies indicate that further research is still needed to warrant their beneficial effects. In the present review article, the roles of MMPs as prognostic indicators, as well as the factors influencing MMP expression, are discussed. Current findings on the role of MMP inhibitors in cardiac remodelling and the prognosis after AMI in both animal models and clinical studies are also examined.

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.

Effects of Selective Matrix Metalloproteinase Inhibitor (PG-116800) to Prevent Ventricular Remodeling After Myocardial Infarction

OBJECTIVES

We sought to determine whether matrix metalloproteinase (MMP) inhibitor, PG-116800, reduced left ventricular (LV) remodeling after myocardial infarction (MI).

BACKGROUND

PG-116800 is an oral MMP inhibitor with significant antiremodeling effects in animal models of MI and ischemic heart failure.

METHODS

In an international, randomized, double-blind, placebo-controlled study, 253 patients with first ST-segment elevation MI and ejection fraction between 15% and 40% were enrolled 48+/- 24 h after MI and treated with placebo or PG-116800 for 90 days. Major efficacy end points were changes in LV volumes as determined by serial echocardiography, and clinical and safety outcomes were also collected.

RESULTS

In total, 203 patients (80%) completed 90 days of treatment and had evaluable baseline and 90-day echocardiograms. The proportion of patients with anterior MI (78% vs. 81%) and primary percutaneous coronary intervention (90% vs. 91%) along with baseline LV ejection fraction (35.5% vs. 36.8%) did not differ between PG-116800-treated and placebo-treated patients. There was no difference in the change in LV end-diastolic volume index from days 0 to 90 with PG-116800 versus placebo (5.09 +/- 1.45 ml/m(2) vs. 5.48 +/- 1.41 ml/m2, p = 0.42). Changes in LV diastolic volume, LV systolic volume, LV ejection fraction, sphericity index, plus rates of death or reinfarction were not significantly improved with PG-116800. PG-116800 was well tolerated; however, there was increased incidence of arthralgia and joint stiffness without significant increase in overall musculoskeletal adverse events (21% vs. 15%, p = 0.33).

CONCLUSIONS

Matrix metalloproteinase inhibition with PG-116800 failed to reduce LV remodeling or improve clinical outcomes after MI.

Cardiac support device modifies left ventricular geometry and myocardial structure after myocardial infarction

BACKGROUND

Whether mechanical restraint of the left ventricle (LV) can influence remodeling after myocardial infarction (MI) remains poorly understood. This study surgically placed a cardiac support device (CSD) over the entire LV and examined LV and myocyte geometry and function after MI.

METHODS AND RESULTS

Post-MI sheep (35 to 45 kg; MI size, 23+/-2%) were randomized to placement of the CorCap CSD (Acorn Cardiovascular, Inc) (MI+CSD; n=6) or remained untreated (MI only; n=5). Uninstrumented sheep (n=10) served as controls. At 3 months after MI, LV end-diastolic volume (by MRI) was increased in the MI only group compared with controls (98+/-8 versus 43+/-4 mL; P<0.05). In the MI+CSD group, LV end-diastolic volume was lower than MI only values (56+/-7 mL; P<0.05) but remained higher than controls (P<0.05). Isolated LV myocyte shortening velocity was reduced by 35% from control values (P<0.05) in both MI groups. LV myocyte beta-adrenergic response was reduced with MI but normalized in the MI+CSD group. LV myocyte length increased in the MI group and was reduced in the MI+CSD group. Relative collagen content was increased and matrix metalloproteinase-9 was decreased within the MI border region of the CSD group.

CONCLUSIONS

A CSD beneficially modified LV and myocyte remodeling after MI through both cellular and extracellular mechanisms. These findings provide evidence that nonpharmacological strategies can interrupt adverse LV remodeling after MI.

Circulating biomarkers of extracellular matrix remodeling and risk of atherosclerotic events

PURPOSE OF REVIEW

Disturbances of the synthesis and breakdown of the extracellular matrix of arterial walls have emerged as key features of the atherosclerotic process. Altered levels of circulating extracellular matrix markers have frequently been observed in relation to manifestations of atherosclerotic disease and its risk factors.

RECENT FINDINGS

Research has been focused on the matrix-degrading metalloproteinases, their tissue inhibitors, and procollagen peptides. The most promising matrix metalloproteinase is matrix metalloproteinase-9, which has been observed to predict rapid coronary artery narrowing, ischemic heart disease incidence, abdominal aortic aneurysm expansion, worse outcome in stroke patients, and cardiovascular death. The use of tissue inhibitors of metalloproteinases for prognostication is uncertain thus far. The procollagen marker with most prognostic potential is the marker for type III collagen turnover rate, the N-terminal propeptide PIIINP, higher levels of which predict an adverse outcome after a myocardial infarction and in chronic heart failure, and portend abdominal aortic aneurysm expansion and risk of rupture. Also, the marker for type I collagen synthesis, the C-terminal propeptide PICP, predicts adverse outcomes following myocardial infarction and in chronic heart failure. Extracellular matrix remodeling is also a promising therapeutic target, being favorably affected by several conventional cardiovascular drugs and select dietary interventions. Synthetic matrix metalloproteinase inhibitors are also under development.

SUMMARY

Circulating matrix markers have emerged as candidate biomarkers for predicting risk of subsequent atherosclerotic events. Future large longitudinal observational and intervention studies will determine the role of matrix biomarkers in diagnosis and prognostication, and as targets for intervention in cardiovascular diseases.

Statins and postoperative risk of atrial fibrillation following coronary artery bypass grafting

Atrial fibrillation (AF) is a common complication after coronary artery bypass grafting. Atrial remodeling has been observed in AF and has been associated with the development of this arrhythmia. Because 3-hydroxy-3-methylglutaryl coenzyme A inhibitors (statins) have been demonstrated to modify remodeling, we hypothesized a protective role of statins against postoperative AF. We also hypothesized that extracellular matrix turnover and brain natriuretic peptide (BNP) might be related to such atrial remodeling. We studied 234 consecutive patients who underwent coronary artery bypass grafting (173 men; 65 +/- 9 years of age) in whom the occurrence of postoperative AF was monitored. In a subgroup of 66 patients, we measured plasma levels of matrix metalloproteinase-1 (MMP-1), its inhibitor, tissue inhibitor matrix metalloproteinase-1 (TIMP-1; as indexes of extracellular matrix remodeling), and N-terminus pro-BNP (related to left ventricular function) at baseline and at 24 hours after surgery. Of 234 patients, 66 (28.2%) developed postoperative AF. In multivariate analysis, previous AF was related to an increase in the development of AF (odds ratio 11.92, 95% confidence interval 2.37 to 59.98, p = 0.026), whereas statin use was related to a decrease in arrhythmia (odds ratio 0.52, 95% confidence interval 0.28 to 0.96, p = 0.038). A higher TIMP-1/MMP-1 ratio at 24 hours after surgery was present in those who did not develop postoperative AF (p = 0.043). Statin use was associated with increased TIMP-1 levels and TIMP-1/MMP-1 ratio (p = 0.027 and 0.036, respectively). No significant relations to N-terminus pro-BNP were seen. In conclusion, previous AF and nonuse of statins are significantly associated with AF after coronary artery bypass grafting. Statin use may be protective against AF after coronary artery bypass grafting, possibly due to alterations in the extracellular matrix and remodeling after coronary artery bypass grafting.

Matrix metalloproteinases and failed fracture healing

During fracture healing and the resulting formation of new bone, an extensive amount of extracellular matrix is synthesized which subsequently undergoes enzymatic remodeling and then mineralization. The remodeling process of mostly collagenous molecules is largely attributable to matrix metalloproteinases (MMPs). A variety of members of this protease family and its respective inhibitors - termed tissue inhibitors of matrix metalloproteinases (TIMP) - have been found to be closely related to the fracture healing process. Delays in bone healing or even nonunion could be related to the concentrations of these enzymes or their behavior over time. In this study, serum samples were prospectively collected from patients who had undergone surgical treatment for limb fracture. Serum probes from 15 patients with nonunion of fractures 4 months after surgery have been compared to 15 matched patients with normal bone healing. Postoperative time courses of serum concentrations of MMP-1/-2/-3/-8/-9/-13 as well as TIMP-1/-2 were analyzed using commercially available enzyme immunoassays. Comparison between both collectives revealed significantly elevated serum concentrations of proMMP-1 in the nonunion group at 2 and 24 weeks after surgery. Similar findings were found for MMP-8 at 2, 4 and 8 weeks. At 1 week after surgery, TIMP-1 serum concentrations were significantly lower in nonunion patients when compared to patients with normal bone repair. We have been able to show for the first time the course of serum concentrations of MMPs and TIMPs during normal and delayed fracture healing. Characteristic time courses of systemic MMP- and TIMP-levels could be a reflection of local enzyme regulatory mechanisms during fracture healing. An altered balance of the MMP/TIMP system in favor of proteolytic activity as shown in our investigation may be involved in the pathophysiological processes leading to fracture nonunion.

Prognostic value of tissue inhibitor of metalloproteinase-1 for cardiovascular death among patients with cardiovascular disease: results from the AtheroGene study

AIMS

Metalloproteinases are proteolytic enzymes, which decompose the extracellular matrix, influence cardiac remodelling, and are inhibited by tissue inhibitor of metalloproteinases (TIMPs). Little is known about the prognostic impact of the TIMP-1/matrix metalloproteinase complex in patients with future cardiovascular death.

METHODS AND RESULTS

In 1979 patients with suspected coronary artery disease (CAD), TIMP-1 has been determined at baseline. Among 1945 (98.4%) patients with a mean follow-up period of 2.6+/-1.2 years, 75 patients died because of cardiovascular causes. Mean concentrations of TIMP-1 were higher among patients who experienced a fatal cardiovascular event than among those who did not (820 vs. 692 ng/mL; P<0.001). Age and sex adjusted hazard ratio of future cardiovascular death associated with one standard deviation of TIMP-1 level, was 1.37 (95% CI: 1.17-1.61; P<0.001). The hazard ratio remained nearly identical after adjustment for clinical and therapeutic confounders. B-type natriuretic peptide (2.75, 95% CI: 1.94-3.89; P<0.001), C-reactive protein (1.79, 95% CI: 1.43-2.24; P<0.001), and TIMP-1 (1.30, 95% CI: 1.07-1.58; P=0.008) were independently associated with future cardiovascular death.

CONCLUSION

In patients with CAD, TIMP-1 proves as an independent predictor for future cardiovascular death.

Infarct Size Reduction and Attenuation of Global Left Ventricular Remodeling with the CorCapTM Cardiac Support Device Following Acute Myocardial Infarction in Sheep

BACKGROUND

Whether mechanical restraint of the left ventricle (LV) can influence remodeling following myocardial infarction (MI) remains poorly understood. The following discussion details three studies examining the effects of surgically placing a cardiac support device (CSD) over the entire epicardial surface, on infarct expansion, global cardiac function and myocyte geometry and function post-MI.

METHODS

The effects of passive constraint on infarct expansion and global cardiac function/myocardial energetics were investigated in 10 sheep (5 MI only; 5 MI + CSD) using pressure-volume analysis and magnetic resonance imaging (MRI). Additionally, 11 sheep (5 MI only; 6 MI + CSD) were used to study the effects of passive restraint on myocyte geometry and function post-MI, with 10 additional uninstrumented sheep serving as controls. Baseline data was collected followed by the creation of an anterior infarct. 1 week post-infarct the animals underwent a second set of data collection studies followed by placement of the CSD in the experimental groups. Additional data was collected at 2 and 3 months post-MI. The animals in the myocyte function group underwent additional studies immediately following the 3 month time point.

RESULTS

Infarct expansion was diminished as a result of the CSD. At 1 week post-MI the akinetic area was similar in both groups. At the terminal time-point, the akinetic area in the control group was similar to the 1-week time-point whereas, in the CSD group, the area of akinesis decreased (P = 0.001). A comparison of the two groups at the terminal time-point demonstrates a significantly diminished area of akinesis in the CSD group (P = 0.004). The relative area of akinesis followed a similar pattern. The CSD group also exhibited a decrease in end-diastolic volume (control 110.3 +/- 19.8 mL vs. CSD 67.6 +/- 4.7 mL, P = .006) and an improved ejection fraction (control 15.5% +/- 5.7% vs. CSD 29.46% +/- 4.42%, P = .008) relative to the control group. Myocardial energetics were also enhanced in the CSD group as evidenced by significant improvements in potential energy (control 2,015 +/- 503 mL x mm Hg/beat vs. CSD 885 +/- 220 mL x Hg/beat, P = .006), efficiency (control 39.4% +/- 13.6% vs. CSD 59.8% +/- 8.5%, P = .044), and oxygen consumption (control 0.072 +/- 0.013 mL O(2)/beat vs. CSD 0.052 +/- 0.007 mL O(2)/beat, P = .034). Isolated LV myocyte shortening velocity was reduced by 35% from control values (P < 0.05) in both MI groups. LV myocyte beta-adrenergic response was reduced with MI, but normalized in the MI + CSD group. Relative collagen content was increased and matrix metalloproteinase-9 was decreased within the MI border region of the CSD group.

CONCLUSIONS

The CorCap cardiac support device retarded infarct expansion, improved global and regional cardiac function and beneficially modified LV and myocyte remodeling post-MI. These findings provide evidence that non-pharmacological strategies can interrupt adverse LV remodeling post-MI.

Time-dependent changes in plasma osteopontin levels in patients with anterior-wall acute myocardial infarction after successful reperfusion: Correlation with left-ventricular volume and function

Osteopontin is a secreted extracellular-matrix glycoprotein that plays a role in the healing of remodeling tissue. We examined the relationship of plasma osteopontin levels with left-ventricular (LV) volume and function in 18 consecutive patients who underwent successful reperfusion after anterior-wall acute myocardial infarction (AMI). The plasma osteopontin level was within the control range at admission (mean +/- SD 420 +/- 195 ng/mL), began to increase on day 2 (935 +/- 464 ng/mL), and reached a maximum around day 3 (1139 +/- 482 ng/mL). The level remained high on days 4, 5, and 7 ( approximately 1000 ng/mL) and then decreased on day 14. Maximal plasma osteopontin levels and the difference between maximal and minimal levels were positively correlated with LV end-systolic volume index (r = .58, P < .05; and r = .65, P < .01, respectively) and negatively correlated with LV ejection fraction (r = -.52, P < .05; and r = -.60, P < .01, respectively). The area under the curve of plasma osteopontin levels for 14 days after AMI was significantly correlated with LV end-systolic volume index (r = .66, P < .01), LV end-diastolic volume index (r = .50, P < .05), and LV ejection fraction (r = -.55, P < .05). In subgroup patients with the same area of risk for myocardial infarction (ie, responsible lesions located at the same proximal left anterior descending coronary artery), essentially the same or a closer relationship between plasma osteopontin level and LV volume and function was noted. Plasma osteopontin levels were correlated substantially with plasma levels of high-sensitivity C-reactive protein (hsCRP) and weakly with serum creatine kinase release. In conclusion, the plasma level of osteopontin changes in a time-dependent fashion and is correlated with LV volumes and function and associated substantially with the extent of the inflammatory response indicated by the plasma hsCRP level and weakly with infarct size estimated on the basis of cardiac-enzyme release.

Ischaemia–reperfusion injury activates matrix metalloproteinases in the human heart

AIMS

Matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) regulate matrix remodelling in the heart and play a pivotal role in myocardial dysfunction immediately following ischaemia-reperfusion injury ex vivo in rats. We investigated the changes in MMPs and TIMPs in acute myocardial ischaemia-reperfusion injury in humans.

METHODS AND RESULTS

Fifteen patients with stable angina undergoing coronary artery bypass graft surgery with cardiopulmonary bypass were enrolled. Left ventricular stroke work index was monitored prior to bypass and for 24 h following reperfusion. Left atrial biopsy samples were obtained at the start of bypass before cardioplegia and within 10 min after removal of the aortic cross-clamp. Plasma samples were collected from the radial artery and coronary sinus 1, 5, and 10 min following removal of the cross-clamp. In cardiac biopsies there was a marked increase in 72 kDa MMP-2 and 92 kDa MMP-9 activities, and a decrease in TIMP-1 upon reperfusion. Increased MMP activity correlated positively with cross-clamp duration and inversely with cardiac mechanical function 3 h following reperfusion. TIMP-1 correlated inversely with cross-clamp time and positively with cardiac mechanical function. Plasma samples revealed a significant increase in both 92 kDa MMP-9 and 64 kDa MMP-2 activities 1 min following removal of cross-clamp.

CONCLUSION

Reperfusion following cardioplegia activates MMPs in the myocardium and plasma of patients undergoing coronary artery bypass grafting. This is the first correlation of MMP myocardial activity with cardiac function in humans. The early increase in MMP activity produces a proteolytic environment that may contribute to myocardial stunning injury in humans.

Matrix metalloproteinase-1 promoter polymorphisms and changes in left ventricular volume following acute myocardial infarction

The relation between matrix metalloproteinase-1 promoter genotype and remodeling was studied in 42 patients after their first acute myocardial infarctions. Patients possessing 2 GG alleles were at increased risk for remodeling compared with homozygotes for the G allele and heterozygotes possessing 1 G and 1 GG allele.

Plasma MMP-9 and MMP-2 following acute myocardial infarction in man: correlation with echocardiographic and neurohumoral parameters of left ventricular dysfunction

BACKGROUND

Left ventricular dilatation and elevated plasma natriuretic peptide levels predict adverse prognosis and the development of congestive heart failure after myocardial infarction. Altered matrix metalloproteinase (MMP) activity has been implicated in the structural changes associated with development of heart failure after myocardial injury. The aims of this study were to investigate plasma MMP-2, MMP-9, and tissue inhibitor of metalloproteinase (TIMP)-1 concentrations following acute myocardial infarction and their relationships with measures of left ventricular function.

METHODS AND RESULTS

Plasma MMP-2, MMP-9, TIMP-1, and N-terminal proBNP (N-BNP) were quantified on 5 consecutive days in 60 patients with acute myocardial infarction (39 anterior). N-BNP was measured on day 3. Echocardiographic assessment of left ventricular wall motion index and volumes was performed during admission and 6 weeks later. Plasma MMP-9 showed peaks on days 1 and 4. MMP-2 levels, similar on each day, were higher after inferior myocardial infarction. Plasma MMP-2 showed strong, inverse correlation with left ventricular volumes during and after admission. Plasma MMP-9 correlated directly with N-BNP (P=.022) and inversely with wall motion index during admission (P=.05). TIMP-1 levels were higher after anterior (1269, 870-1466 ng/mL) compared with inferior (1183, 856-1419 ng/mL, P=.05) acute myocardial infarction and fell from day 1 through 5 (P <.0005).

CONCLUSION

Plasma MMP-9 concentration correlates with neurohormonal and echocardiographic measures of left ventricular dysfunction after myocardial infarction. Higher left ventricular volumes are associated with lower plasma MMP-2 concentrations. Circulating MMP concentrations may provide insights into left ventricular remodeling after acute myocardial infarction.

Markers of Myocardial Damage, Tissue Healing, and Inflammation After Radiofrequency Catheter Ablation of Atrial Tachyarrhythmias

INTRODUCTION

Radiofrequency ablation produces a localized endomyocardial necrosis that may result in release of biochemical markers reflecting myocardial cell damage, inflammation, and tissue reparation. The aim of this study was to determine the extent of rise and time course of markers of inflammation and tissue reparation in patients undergoing radiofrequency catheter ablation.

METHODS AND RESULTS

Serial blood samples were taken from patients with AV nodal reentrant tachycardia (n = 5), Wolff-Parkinson-White syndrome (n = 3), and atrial flutter (n = 5) undergoing radiofrequency ablation. Blood was taken before ablation (day 0, baseline) and at day 1 and day 120 after ablation. The proinflammatory marker interleukin-6 (IL-6), troponin I (TNI), and myoglobin, as well as matrix metalloproteinase-9 (MMP-9), a marker for myocardial healing, were measured by enzyme-linked immunosorbent assay. Levels of IL-6, TNI, myoglobin, and MMP-9 were significantly elevated on day 1 after ablation compared to baseline levels. Seven of the 13 patients had troponin levels greater than the threshold of significant myocardial damage (>0.1 ng/mL) on day 1. Plasma levels of MMP-9 were still elevated on day 120 compared to values before ablation (P = 0.021).

CONCLUSION

Markers of inflammation, wound healing, and myocardial damage are increased in patients who undergo radiofrequency ablation. Levels of MMP-9, a marker for myocardial healing and repair, are still elevated 120 days after the procedure, suggesting that radiofrequency ablation induces tissue damage leading to a long-term process of reparation.

Increased serum matrix metalloproteinase 9 levels in systemic lupus erythematosus patients with neuropsychiatric manifestations and brain magnetic resonance imaging abnormalities

OBJECTIVE

To evaluate whether serum matrix metalloproteinase 9 (MMP-9) levels are associated with neuropsychiatric manifestations, particularly cognitive dysfunction, as evaluated by neuropsychological testing and brain magnetic resonance imaging (MRI) abnormalities in patients with systemic lupus erythematosus (SLE).

METHODS

MMP-9 determinations were made in 44 patients with SLE and 43 healthy controls who underwent a clinical neurologic and neuropsychological investigation in order to identify neuropsychiatric manifestations. Cerebral MRI scans with volumetric estimation of intracranial cerebrospinal fluid spaces, T1-weighted lesions, and T2-weighted lesions were performed for all subjects. SLE activity was assessed by the European Consensus Lupus Activity Measure (ECLAM) index, and accumulated neuropsychiatric abnormality was assessed by the Systemic Lupus International Collaborating Clinics (SLICC)/American College of Rheumatology damage index.

RESULTS

No significant difference was found in serum MMP-9 levels between the overall group of SLE patients and controls. However, SLE patients who had at least 1 neuropsychiatric manifestation (NPSLE patients) had significantly higher serum MMP-9 concentrations than did SLE patients without neuropsychiatric syndromes (P = 0.009). Among patients with NPSLE, those with cognitive deficits had significantly higher concentrations of serum MMP-9 than did those with normal cognitive function (P = 0.027). Furthermore, serum MMP-9 levels had a significant positive correlation with the volumes of T1-weighted and T2-weighted lesions in the brain MRI (P = 0.031 and P = 0.015, respectively). The concentration of serum MMP-9 correlated significantly with the SLICC index but not with the ECLAM index.

CONCLUSION

Elevated levels of serum MMP-9 in patients with SLE may reflect neuropsychiatric involvement, particularly cognitive dysfunction. The serum MMP-9 concentration may be associated with small- vessel cerebral vasculopathy and increased risk of cerebral ischemic events in patients with SLE.

Matrix metalloproteinases are not involved in early brain edema formation after cardiac arrest in rats

INTRODUCTION

Resuscitation from cardiac arrest (CA) often results in a poor neurological outcome possibly due to an incomplete understanding of the pathophysiology of brain injury following CA-induced global cerebral ischemia. Brain edema is an important manifestation after CA and is associated with significant morbidity and mortality. The matrix metalloproteinases (MMPs) contribute to brain edema formation following focal cerebral ischemia. The objective of this study was to investigate the role of an MMP inhibitor, GM6001, in CA-elicited brain edema.

METHODS

Eighteen rats were subjected to normothermic (37.5 +/- 0.5 degrees C) CA induced by eight minutes of asphyxiation and assigned to a CA-control group (CA), an alcohol-placebo group (CA + ETOH), or a GM6001-treated group (CA + GM6001). GM6001 in 100% alcohol or a vehicle was given i.v. before CA to achieve a whole blood concentration of 10 microM. Animals were resuscitated with CPR, ventilation and epinephrine. Brain edema was determined by brain wet-to-dry weight ratio at one hour after resuscitation.

FINDINGS

Brain wet-to-dry weight ratio was 4.86 +/- 0.09 in CA, 4.76 +/- 0.12 in CA + ETOH (p = 0.30 vs. CA), and 4.72 +/- 0.03 in CA + GM6001 (p = 0.17 vs. CA and 0.42 vs. CA + ETOH).

INTERPRETATION

MMPs are not involved in brain edema formation one hour following CA.

Profiles of matrix metalloproteinases, their inhibitors, and laminin in stroke patients: influence of different therapies

BACKGROUND AND PURPOSE

The goal of this study was to determine the temporal profile of several matrix metalloproteinases (MMPs), tissue inhibitors of MMPs (TIMPs), and laminin (an MMP substrate) in human stroke under different treatment paradigms, including thrombolysis and hypothermia.

METHODS

We serially measured the serum levels of MMP-2, MMP-3, MMP-9, MMP-13, TIMP-1, TIMP-2, and laminin in 50 patients with acute ischemic stroke using zymography or enzyme-linked immunosorbent assay. Patients were treated with heparin, therapeutic thrombolysis, or hypothermia. Scandinavian Stroke Scale scores were obtained at baseline. Infarct volume was measured with CT scanning on day 4 after stroke onset. Healthy persons were used as control subjects.

RESULTS

MMP-2 and MMP-9 increased during the course of ischemia, whereas intact laminin and TIMP-2 decreased significantly (P<0.05). MMP-9 and laminin levels varied significantly by infarct size (P=0.001) and therapy (P=0.0005). MMP-9 levels were significantly higher in patients treated with tissue plasminogen activator (tPA) compared with patients treated with hypothermia. The cleaved form of MMP-9 was found solely in 4 patients treated with tPA. Intact laminin levels were significantly lower in the tPA group than in the hypothermia group.

CONCLUSIONS

Selected MMPs and TIMPs are involved in the pathophysiology of acute stroke. This is also reflected by changes in laminin. Treatment paradigms differentially influence levels of MMP-9 and laminin. Combination therapies explicitly involving MMP inhibition could be of value in future treatment strategies.

Serum matrix metalloproteinase-3 and tissue inhibitor of metalloproteinases-1 as potential markers of carotid atherosclerosis in infraclinical hyperlipidemia

The proteolytic activity of proinflammatory matrix metalloproteinases (MMPs) is elevated in lipid-rich atherosclerotic plaques, thereby contributing to plaque fragility and rupture. We hypothesized that changes in circulating levels of MMPs and their specific inhibitors (TIMPs) could reflect the atherosclerotic process occurring within the arterial wall. We determined serum levels of MMP-3, MMP-9, TIMP-1 and TIMP-2 in dyslipidemic subjects and compared them to those of age- and sex-matched normolipidemic healthy controls. Serum levels of MMP-3, MMP-9 and TIMP-1 were significantly increased in hyperlipidemic subjects versus controls (+54, +29 and +15%, respectively; P<0.001). We also noted a trend to elevated serum MMP-3 levels in patients with atherosclerotic lesions when compared to patients free of atherosclerosis (P=0.07). Circulating levels of MMPs and TIMPs were associated neither with those of C-reactive protein, nor with those of alpha2-macroglobulin (a nonspecific MMP inhibitor), nor with intima-media thickness values. Nonetheless, when divided into tertiles, MMP-3 and TIMP-1 levels in the highest tertile were positively associated with the presence of carotid artery lesions (odds ratios=3.4 and 2.0, confidence intervals 1.7-13.9 and 1.3-7.9, respectively). Thus, serum levels of MMP-3, -9 and TIMP-1 are significantly elevated in asymptomatic hyperlipidemic subjects at high cardiovascular risk; however, MMP-3 and TIMP-1 levels are strongly positively associated with the presence of carotid lesions. Such elevations might reflect enhanced vascular matrix remodeling, a key feature of the progression of atherosclerotic disease.

Region- and type-specific induction of matrix metalloproteinases in post-myocardial infarction remodeling

BACKGROUND

Induction of matrix metalloproteinases (MMPs) contributes to adverse remodeling after myocardial infarction (MI). Whether a region- and type-specific distribution of MMPs occurs within the post-MI myocardium remained unknown.

METHODS AND RESULTS

Ten sheep were instrumented with a sonomicrometry array to measure dimensions in 7 distinct regions corresponding to the remote, transition, and MI regions. Eight sheep served as reference controls. The relative abundance of representative MMP types and the tissue inhibitors of the MMPs (TIMPs) was quantified by immunoblotting. Segment length increased from baseline in the remote (24.9+/-5.4%), transition (18.0+/-2.9%), and MI (53.8+/-11.0%) regions at 8 weeks after MI (P<0.05) and was greatest in the MI region (P<0.05). Region- and type-specific changes in MMPs occurred after MI. For example, MMP-1 and MMP-9 abundance was unchanged in the remote, fell to 3+/-2% in the transition, and was undetectable in the MI region (P<0.05). MMP-13, MMP-8, and MT1-MMP increased by >300% in the transition and MI regions (P<0.05). TIMP abundance decreased significantly in the transition region after MI and fell to undetectable levels within the MI region.

CONCLUSIONS

The unique findings of this study were 2-fold. First, changes in regional geometry after MI were associated with changes in MMP levels. Second, a region-specific portfolio of MMPs was induced after MI and was accompanied by a decline in TIMP levels, indicative of a loss of MMP inhibitory control. Targeting the regional imbalance between specific MMPs and TIMPs within the post-MI myocardium holds therapeutic potential.

Is thrombogenesis in atrial fibrillation related to matrix metalloproteinase-1 and its inhibitor, TIMP-1?

BACKGROUND AND PURPOSE

Decreased matrix metalloproteinase-1 (MMP-1) and increased levels of its inhibitor, tissue inhibitor of matrix metalloproteinase-1 (TIMP-1), reflect impaired matrix degradation with an increase in fibrosis. A prothrombotic state has been described in atrial fibrillation (AF), increasing the risk of stroke and thromboembolism. Because structural abnormalities and remodeling of atria have been observed in AF, we hypothesized that the prothrombotic state in AF may be related to abnormal indexes of matrix degradation.

METHODS

We studied 48 consecutive patients (30 men; age, 70.5+/-9.0 years) with chronic nonrheumatic AF who were not on anticoagulation. Plasma levels of MMP-1, TIMP-1, and prothrombin fragment 1+2 (F1+2, an index of thrombogenesis) were measured by enzyme-linked immunosorbent assay. M-mode, 2-dimensional, and Doppler echocardiographic studies were performed in all patients. Research indexes were compared with data from 32 control subjects in sinus rhythm who were of similar age and sex.

RESULTS

Patients with AF had lower levels of MMP-1 (P=0.011) but increased levels of TIMP-1 (P=0.033) and F1+2 (P<0.001) and a higher ratio of TIMP-1 to MMP-1 (P=0.009) compared with control subjects. After adjustment for sex, age, hypertension, and diabetes, TIMP-1 levels and the ratio of TIMP-1 to MMP-1 correlated with F1+2 levels (r=0.24, P=0.038; and r=0.26, P=0.023, respectively). In multivariate analysis, there was no independent relationship between MMP-1, TIMP-1, or ratio of TIMP-1 to MMP-1 and the presence of AF.

CONCLUSIONS

Patients with AF have evidence of impaired matrix degradation, but this was not independently associated with the presence of AF on multivariate analysis. However, an independent relationship was found between the MMP/TIMP system and prothrombotic state (assessed by F1+2 levels).

Increased serum matrix metalloproteinase-1 concentration predicts advanced left ventricular remodeling in patients with acute myocardial infarction

The left ventricular ejection fraction (LVEF) is one of the major prognostic factors after acute myocardial infarction (AMI) and matrix metalloproteinase-1 (MMP-1) is an enzyme responsible for extracellular collagen degradation and remodeling. The present study investigated whether the concentration of serum MMP-1 was associated with the LVEF after AMI. Blood was sampled on admission, and at 24 h, 3 days, 7 days, 2 weeks and 4 weeks in 24 patients with their first AMI. Left ventriculography was performed 4 weeks after the onset of AMI and the LVEF was calculated by center line method. MMP-1 concentrations were higher at 7 days and at 2 weeks than on admission (p<0.001), and at 7 days (r=-0.655, p=0.0005) and at 2 weeks (r=-0.636, p=0.0008) were negatively correlated with the LVEF. The patients with AMI were divided into high and low LVEF groups according to the results of left ventriculography. Although there were no differences in the clinical characteristics between the 2 LVEF groups, the MMP-1 concentrations at 24 h (p<0.01), 7 days (p<0.01) and 2 weeks (p<0.05) were lower in the high LVEF group than in low LVEF group. A high concentration of MMP-1 at the subacute phase after AMI predicts advanced left ventricular remodeling.

Matrix metalloproteinases and coronary artery diseases

Matrix metalloproteinases (MMPs) play an important role in cardiovascular remodeling by degrading the extracellular matrix. Enhanced MMP expression has been detected in the atherosclerotic plaque, and activation of MMPs appears to be involved in the vulnerability of the plaque. Circulating MMP levels are elevated in patients with acute myocardial infarction and unstable angina. Increased MMP expression is also observed after coronary angioplasty, which is related to late loss index after the procedure. These observations suggest that MMP expression may be not only related to instability of the plaque, but also to the formation of restenotic lesions. The development of therapeutic drugs targeted specifically against MMPs may be useful in the prevention of atherosclerotic lesion development, plaque rupture, and restenosis.