Plasma matrix metalloproteinase-9 and left ventricular remodelling after acute myocardial infarction in man: a prospective cohort study

Established and novel biomarkers in ST-elevation myocardial infarction

Cardiac biomarkers assist in the diagnosis of and risk stratification in acute coronary syndromes. In ST-elevation myocardial infarction (STEMI), rapid diagnosis and initiation of reperfusion via primary percutaneous coronary intervention or fibrinolysis is often based on the clinical history and presenting ECG, but measurement of biomarkers in the early and/or late phases of STEMI may allow the selection of patients who are at increased or decreased risk of subsequent complications. Although the measurement of only three biomarkers (troponin, natriuretic peptides and C-reactive protein) are currently included in practice guidelines, more than 20 other novel cardiac biomarkers have been proposed to provide improved risk stratification after a STEMI.

Proteomic analysis of plasma samples from patients with acute myocardial infarction identifies haptoglobin as a potential prognostic biomarker

Prognosis of clinical outcome following myocardial infarction is variable and difficult to predict. We have analyzed the plasma proteome of thirty patients with acute myocardial infarction to search for new prognostic biomarkers. Proteomic analyses of blood samples were performed by 2-D-DiGE after plasma depletion of albumin and immunoglobulins G. New York Heart Association (NYHA) class determined at 1-year follow-up was used to identify patients with heart failure. Principal component analysis and hierarchical clustering of proteomic data revealed that patients could be separated into 3 groups. The 22 differentially expressed proteins involved in this grouping were identified as haptoglobin (Hp) and respective isoforms. The 3 groups of patients had distinct Hp isoforms: patients from group 1 had the α1-α1, patients from group 2 the α2-α1, and patients from group 3 the α2-α2 genotype. This classification was also associated with different total plasma levels of Hp. The presence of the α2 genotype and low plasma levels of Hp was associated with a higher NYHA class and therefore with a detrimental functional outcome after myocardial infarction. A plasma level of Hp below 1.4g/L predicted the occurrence of heart failure (NYHA 2, 3, 4) at 1-year with 100% sensitivity.

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.

Plasma TIMP-4 predicts left ventricular remodeling after acute myocardial infarction

BACKGROUND

Alterations in the balance between matrix metalloproteinases and their endogenous tissue inhibitors (TIMPs) are associated with left ventricular (LV) remodeling after acute myocardial infarction (AMI). No relationships have been identified between TIMPs and serial postinfarction change in LV function.

METHODS AND RESULTS

Plasma concentrations of TIMP-1, -2, -4 were measured at baseline (mean 46 h) and at 24 weeks in 100 patients (age 58.9 ± 12 years, 77% male) admitted with AMI and LV dysfunction, with cardiac magnetic resonance imaging at each time point. TIMP-1 concentration was reduced, whereas TIMP-2 and -4 concentrations were elevated at baseline compared with a reference control population. TIMP-1 decreased and TIMP-2 increased significantly over time; there was an incremental trend in TIMP-4 concentration. Baseline TIMP-4 correlated with change in LV end-systolic volume index (∆LVESVI; r = 0.24; P = .023) and change in LV end-diastolic volume index (∆LVEDVI; r = 0.25; P = .015). ∆TIMP-4 also correlated with ∆LVESVI and with ∆LVEDVI, as did ∆TIMP-2. On multivariable analysis, baseline TIMP-4 concentration was an independent predictor of ∆LVESVI.

CONCLUSIONS

Plasma TIMP-4 concentration, measured early after AMI, may assist in the prediction of LV remodeling and therefore in the assessment of prognosis. Further study of the role of the TIMPs in the pathophysiology of postinfarction remodeling is warranted.

Matrix metalloproteinase-9 functional promoter polymorphism 1562C>T increased risk of early-onset coronary artery disease

The Matrix metalloproteinase-9 functional promoter polymorphism 1562C>T may be considered an important genetic determinant of early-onset coronary artery disease (ECAD). In this study, association between MMP-9 1562C>T allele with plasma MMP-9 activity, homocysteine and lipid-lipoproteins level and ECAD in Iranian subjects was investigated. This case-control study consisted of 53 ECAD patients (age < 55 years) and unrelated late-onsets CAD (age>70 years) who angiographically had at least 50% stenosis. MMP-9 1562C>T polymorphism was detected by PCRRFLP, plasma MMP-9 activity, serum lipid and homocysteine levels were determined by gelatin gel zymography, enzyme assay and by HPLC, respectively. The presence of MMP-9 1562C>T allele was found to be associated with ECAD (OR=3.2, P=0.001). The ECAD patients with MMP-9 1562C>T allele had higher MMP-9 activity (P=0.001), LDL-C (P=0.045), TC (P=0.02) and homocysteine (P=0.01) levels than the LCAD subjects. MMP-9 1562C>T allele is a risk factor for ECAD. The carriers of this allele have high levels of MMP-9 activity, LDL-C, TC and homocysteine (P=0.01), thus, are more likely to develop myocardial infarction and CAD at young age (less than 55 years).

Combining experimental and mathematical modeling to reveal mechanisms of macrophage-dependent left ventricular remodeling

Background

Progressive remodeling of the left ventricle (LV) following myocardial infarction (MI) can lead to congestive heart failure, but the underlying initiation factors remain poorly defined. The objective of this study, accordingly, was to determine the key factors and elucidate the regulatory mechanisms of LV remodeling using integrated computational and experimental approaches.

Results

By examining the extracellular matrix (ECM) gene expression and plasma analyte levels in C57/BL6J mice LV post-MI and ECM gene responses to transforming growth factor (TGF-β₁) in cultured cardiac fibroblasts, we found that key factors in LV remodeling included macrophages, fibroblasts, transforming growth factor-β₁, matrix metalloproteinase-9 (MMP-9), and specific collagen subtypes. We established a mathematical model to study LV remodeling post-MI by quantifying the dynamic balance between ECM construction and destruction. The mathematical model incorporated the key factors and demonstrated that TGF-β₁ stimuli and MMP-9 interventions with different strengths and intervention times lead to different LV remodeling outcomes. The predictions of the mathematical model fell within the range of experimental measurements for these interventions, providing validation for the model.

Conclusions

In conclusion, our results demonstrated that the balance between ECM synthesis and degradation, controlled by interactions of specific key factors, determines the LV remodeling outcomes. Our mathematical model, based on the balance between ECM construction and destruction, provides a useful tool for studying the regulatory mechanisms and for predicting LV remodeling outcomes.

Markers of progenitor cell recruitment and differentiation rise early during ischemia and continue during resuscitation in a porcine acute ischemia model

Clinical administration of bone marrow-derived stem cells in the setting of acute myocardial infarction (AMI) leads to improved left ventricular ejection fraction. Thymosin beta-4 (TB4) and vascular endothelial growth factor (VEGF) are linked to adult epicardial progenitor cell mobilization and neovascularization and is cardioprotective after myocardial ischemia. This study investigated the time course of TB4 and VEGF during AMI, cardiac arrest, and resuscitation. Fifteen anesthetized and instrumented domestic swine underwent balloon occlusion of the proximal left anterior descending coronary artery. During occlusion, venous blood samples were collected from the right atrium at 5-min intervals until 15 min after the onset of cardiopulmonary resuscitation (CPR). Plasma levels of TB4, VEGF, and matrix metalloproteinase-9 (MMP-9, selected as a marker for remodeling and repair) were measured by ELISA. Generalized linear mixed models were employed to model the time-dependent change in plasma concentration. All variables were natural log transformed, except TB4 values, to normalize distributions. Fifteen animals successfully underwent balloon occlusion of the left anterior descending coronary artery and samples were collected from these subjects. The average onset of spontaneous ventricular fibrillation was 28 min. TB4, VEGF, and MMP-9 demonstrated a statistically significant, time-dependent increase in concentration during ischemia. Following arrest and throughout the first 15 min of resuscitation, MMP-9 had an unchanged rate of rise when compared with the prearrest, ischemic period, with VEGF showing a deceleration in its time-dependent concentration trajectory and TB4 demonstrating an acceleration. Endogenous TB4 and VEGF increase shortly after the onset of AMI and increase through cardiac arrest and resuscitation in parallel to remodeling proteases. These markers continue to rise during successful resuscitation and may represent an endogenous mechanism to recruit undifferentiated stem cells to areas of myocardial injury.

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.

Anti-apolipoprotein A-1 IgG predicts major cardiovascular events in patients with rheumatoid arthritis

OBJECTIVE

To determine whether anti-apolipoprotein A-1 (anti-Apo A-1) IgG are associated with major cardiovascular events in patients with rheumatoid arthritis (RA).

METHODS

We determined anti-Apo A-1 IgG levels and the concentrations of cytokines, oxidized low-density lipoprotein (LDL), and matrix metalloproteinase 1 (MMP-1) MMP-2, MMP-3, and MMP-9 in sera from 133 patients with RA who did not have cardiovascular disease at baseline, all of whom were longitudinally followed up over a median period of 9 years. A major cardiovascular event was defined as a fatal or nonfatal stroke or acute coronary syndrome. The proinflammatory effects of anti-Apo A-1 IgG were assessed on human macrophages in vitro.

RESULTS

During followup, the overall incidence of major cardiovascular events was 15% (20 of 133 patients). At baseline, anti-Apo A-1 IgG positivity was 17% and was associated with a higher incidence of major cardiovascular events (adjusted hazard ratio 4.2, 95% confidence interval 1.5-12.1). Patients who experienced a subsequent major cardiovascular event had higher circulating levels of anti-Apo A-1 IgG at baseline compared with those who did not have a major cardiovascular event. Receiver operating curve analysis showed that anti-Apo A-1 IgG was the strongest of all tested biomarkers for the prediction of a subsequent major cardiovascular event, with an area under the curve value of 0.73 (P = 0.0008). At the predefined and previously validated cutoff levels, the specificity and sensitivity of anti-Apo A-1 IgG to predict major cardiovascular events were 50% and 90%, respectively. Anti-Apo A-1 IgG positivity was associated with higher median circulating levels of interleukin-8 (IL-8), oxidized LDL, and MMP-9 and higher proMMP-9 activity as assessed by zymography. On human macrophages, anti-Apo A-1 IgG induced a significant dose-dependent increase in IL-8 and MMP-9 levels and proMMP-9 activity.

CONCLUSION

Anti-Apo A-1 IgG is an independent predictor of major cardiovascular events in RA, possibly by affecting vulnerability to atherosclerotic plaque.

Usefulness of plasma tissue inhibitors of metalloproteinases as markers of prognosis after acute myocardial infarction

Alterations in the balance of matrix metalloproteinase to tissue inhibitor of metalloproteinase (TIMP) are seen after acute myocardial infarction (AMI) and are associated with adverse left ventricular remodeling and prognosis in this setting. We aimed to investigate the association between TIMP levels and the occurrence of major adverse cardiac events (MACEs) after AMI. We measured plasma TIMP-1, -2, and -4 levels in 1,313 patients presenting with AMI. Subjects were followed over a median period of 520 days for the occurrence of MACEs. Clinical risk was assessed using the Global Registry of Acute Coronary Events (GRACE) score. All TIMP levels correlated with patient age and inversely with estimated glomerular filtration rate (all p values <0.001). Levels were higher in women versus men (p <0.001) and in subjects with a history of diabetes (TIMP-1, p <0.001; TIMP-2, p = 0.002; TIMP-4, p <0.001) or hypertension (TIMP-1, p = 0.031; TIMP-2, p <0.001; TIMP-4, p <0.001). TIMP-1 and TIMP-4 were higher in subjects with previous MI or angina (p <0.001). TIMP levels increased incrementally with quartiles of GRACE score (p <0.001). All TIMPs showed univariate association with the occurrence of MACEs (p <0.001). Areas under the receiver operator characteristic curve for prediction of MACE at 1 year were 0.61 for TIMP-1, 0.57 for TIMP-2, and 0.64 for TIMP-4. Combination of TIMPs with GRACE risk score revealed a greater area under the curve than GRACE score alone (0.72 vs 0.69, p = 0.0015). On multivariable Cox proportional hazards analysis, GRACE score (p <0.001) and plasma TIMPs (log TIMP-1, p = 0.017; log TIMP-2, p <0.001; log TIMP-4, p = 0.011) independently predicted MACEs. Using Kaplan-Meier analysis, the risk of MACEs increased incrementally with the number of TIMPs above their respective median (p <0.001 for all comparisons, log-rank test). In conclusion, higher plasma TIMP-1, -2, and -4 after AMI are associated with MACEs and provide additional prognostic information to that obtained from GRACE clinical risk scores alone.

Tissue plasminogen activator antigen predicts medium-term left ventricular end-systolic volume after acute myocardial infarction

Von Willebrand factor (VWF) and tissue plasminogen activator (t-PA) predict adverse cardiovascular outcome following acute myocardial infarction (AMI) and are weakly associated with pre-discharge left ventricular ejection fraction (LVEF). We examined the relationships between VWF, t-PA antigen, matrix metalloproteinase (MMP)-2,-3, and -9, and B-type natriuretic peptide (BNP), and their predictive effect on serial change in LV volumes in a cohort of patients admitted with AMI. Plasma VWF, t-PA antigen, MMP-2,-3,-9, and BNP were measured at a mean 46 h after AMI in 100 patients (mean age 58.9 +/- 12 years, 77% male) with depressed LVEF. Cardiac magnetic resonance (CMR) imaging was then performed. Biomarker measurement and CMR were repeated at 12 and 24 weeks. Plasma concentrations of VWF, BNP and MMP-9 were elevated while t-PA antigen concentration was at the upper limits of normal; over 24 weeks VWF, t-PA antigen, MMP-9 and BNP decreased significantly. Baseline VWF correlated with BNP (r = 0.35, P < 0.001) and MMP-3 (r = 0.24, P = 0.019) as did t-PA antigen (r = 0.27, P = 0.007 for BNP; r = 0.40, P < 0.001 for MMP-3). t-PA antigen, VWF, MMP-3 and BNP were univariate predictors of LV end-systolic volume at 24 weeks; tPA antigen and BNP remained significant independent predictors on multivariate analysis. t-PA antigen and VWF are related to medium-term LV volumes after AMI, and to MMP-3. This novel link between the coagulation-fibrinolysis system and matrix turnover merits further study in understanding the pathophysiology of adverse ventricular remodeling after AMI.

Biomarkers in acute myocardial infarction

Myocardial infarction causes significant mortality and morbidity. Timely diagnosis allows clinicians to risk stratify their patients and select appropriate treatment. Biomarkers have been used to assist with timely diagnosis, while an increasing number of novel markers have been identified to predict outcome following an acute myocardial infarction or acute coronary syndrome. This may facilitate tailoring of appropriate therapy to high-risk patients. This review focuses on a variety of promising biomarkers which provide diagnostic and prognostic information. Heart-type Fatty Acid Binding Protein and copeptin in combination with cardiac troponin help diagnose myocardial infarction or acute coronary syndrome in the early hours following symptoms. An elevated N-Terminal Pro-B-type Natriuretic Peptide has been well validated to predict death and heart failure following a myocardial infarction. Similarly other biomarkers such as Mid-regional pro-Atrial Natriuretic Peptide, ST2, C-Terminal pro-endothelin 1, Mid-regional pro-Adrenomedullin and copeptin all provide incremental information in predicting death and heart failure. Growth differentiation factor-15 and high-sensitivity C-reactive protein predict death following an acute coronary syndrome. Pregnancy associated plasma protein A levels following chest pain predicts risk of myocardial infarction and revascularisation. Some biomarkers such as myeloperoxidase and high-sensitivity C-reactive protein in an apparently healthy population predicts risk of coronary disease and allows clinicians to initiate early preventative treatment. In addition to biomarkers, various well-validated scoring systems based on clinical characteristics are available to help clinicians predict mortality risk, such as the Thrombolysis In Myocardial Infarction score and Global Registry of Acute Coronary Events score. A multimarker approach incorporating biomarkers and clinical scores will increase the prognostic accuracy. However, it is important to note that only troponin has been used to direct therapeutic intervention and none of the new prognostic biomarkers have been tested and proven to alter outcome of therapeutic intervention. Novel biomarkers have improved prediction of outcome in acute myocardial infarction, but none have been demonstrated to alter the outcome of a particular therapy or management strategy. Randomised trials are urgently needed to address this translational gap before the use of novel biomarkers becomes common practice to facilitate tailored treatment following an acute coronary event.

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.

Coordinated modular functionality and prognostic potential of a heart failure biomarker-driven interaction network

Background

The identification of potentially relevant biomarkers and a deeper understanding of molecular mechanisms related to heart failure (HF) development can be enhanced by the implementation of biological network-based analyses. To support these efforts, here we report a global network of protein-protein interactions (PPIs) relevant to HF, which was characterized through integrative bioinformatic analyses of multiple sources of "omic" information.

Results

We found that the structural and functional architecture of this PPI network is highly modular. These network modules can be assigned to specialized processes, specific cellular regions and their functional roles tend to partially overlap. Our results suggest that HF biomarkers may be defined as key coordinators of intra- and inter-module communication. Putative biomarkers can, in general, be distinguished as "information traffic" mediators within this network. The top high traffic proteins are encoded by genes that are not highly differentially expressed across HF and non-HF patients. Nevertheless, we present evidence that the integration of expression patterns from high traffic genes may support accurate prediction of HF. We quantitatively demonstrate that intra- and inter-module functional activity may be controlled by a family of transcription factors known to be associated with the prevention of hypertrophy.

Conclusion

The systems-driven analysis reported here provides the basis for the identification of potentially novel biomarkers and understanding HF-related mechanisms in a more comprehensive and integrated way.

Plasma matrix metalloproteinase-9 better predicts outcome than N-terminal protype-B natriuretic peptide in patients with systolic heart failure and a high prevalence of coronary artery disease

Metalloproteinases have been proposed as biochemical markers of left ventricular (LV) remodeling in systolic heart failure (HF). However, their role in the prognostic stratification of these patients remains controversial. In the present study, we aimed at investigating the value of plasma metalloproteinases-3 and -9 in comparison with N-terminal protype-B natriuretic peptide in patients with systolic HF. One hundred and 27 consecutive patients hospitalized for systolic HF (LV ejection fraction < 45%) were enrolled. Coronary artery disease (CAD) was the aetiology in 67% of the study patients. Plasma metalloproteinases-3 and -9 and N-terminal protype-B natriuretic peptide levels were assessed. A complete echocardiographic and Doppler examination was also performed. Follow-up period was 24-15 months. On univariate analysis, a number of measurements predicted cardiac events in the following order of power: NYHA class >2, LV ejection fraction < 25%, metalloproteinases-9 > 238 ng/ml, mitral E wave deceleration time < 150 ms, N-terminal protype-B natriuretic peptide > 1586 pg/ml and metalloproteinases-3 > 15 ng/ml. However, on multivariate analysis the only independent variables of cardiac events were NYHA class (OR=2.26, p=0.059) and plasma metalloproteinases-9 (OR=2.00, p=0.029). On Kaplan-Meier survival analysis, patients with elevated levels of metalloproteinases-9 exhibited a significantly worse event free-survival at 45 months than those without (21% vs. 54%, log-rank: 13.93, p=0.0002). A worse survival was also observed in patients with elevated N-terminal protype-B natriuretic peptide levels with respect to those without (18% vs. 46%, log-rank: 9.11, p=0.025). Our results demonstrated the value of plasma metalloproteinases-9 levels for prognostication of patients with systolic HF and a high prevalence of CAD.

Circulating matrix metalloproteinase-3 and metalloproteinase-9 and tissue Doppler measures of diastolic dysfunction to risk stratify patients with systolic heart failure

Abnormal matrix metalloproteinase (MMP) activity and diastolic dysfunction may affect left ventricular (LV) remodeling and prognosis, but it is not known whether the combined evaluation of MMP-3 and MMP-9 and variables of diastolic dysfunction are useful for the risk stratification of patients with systolic heart failure (HF). Therefore, this study was designed to assess the value of combining circulating levels of MMPs and tissue Doppler measures of LV diastolic dysfunction to risk-stratify patients with systolic HF. Consecutive patients with systolic HF due to either ischemic or nonischemic cardiomyopathy (n = 134) and LV ejection fractions <45% were submitted to complete echocardiographic and Doppler examinations. The ratio of mitral E peak velocity and averaged e' velocity (E/e') was calculated. Plasma levels of MMP-3 and MMP-9 were measured at the time of index echocardiography. All-cause mortality was defined as the end point. The mean LV ejection fraction was 28 +/- 9%. There was a total of 32 deaths during follow-up (24 +/- 14 months). Several clinical, biochemical, Doppler, and echocardiographic parameters were associated with the outcome on univariate Cox regression analysis. After statistical adjustment for the potentially confounding factors by multivariate analysis, E/e' (hazard ratio 1.11, p = 0.0028), ejection fraction (hazard ratio 0.92, p = 0.017), and MMP-9 (hazard ratio 1.01, p = 0.027) remained significant independent predictors of the end point. Kaplan-Meier curves showed that survival was worse in patients with E/e' ratios >/=13 and MMP-9 levels >89.9 ng/mL (p <0.0001). In conclusion, the assessment of circulating MMP levels and tissue Doppler measures of LV diastolic dysfunction may improve the prognostic stratification of patients with systolic HF.

Ghrelin inhibits post-infarct myocardial remodeling and improves cardiac function through anti-inflammation effect

Ghrelin is a novel growth hormone-releasing peptide, which has been shown to exert beneficial cardiac effects on chronic heart failure (CHF) recently. In this study, we attempted to investigate the mechanisms for the effect of ghrelin on ventricular remodeling following acute myocardial infarction (MI). Ligation of a coronary artery was used to create an MI in rats. One week after MI, ghrelin (100 microg/kg) or saline was injected subcutaneously twice a day for 4 weeks. When compared to sham groups, ghrelin administration significantly decreased left ventricular (LV) remodeling in post-MI rats, as indicated by increased LV maximum rate of pressure, LV fractional shortening and scar thickness; and decreased LV end-diastolic pressure, LV end-systolic diameter, LV end-diastolic diameter and cardiocytocytes apoptosis. Moreover, ghrelin inhibited the inflammatory response, as shown by decreased mRNA and protein levels of interleukin (IL)-1beta and tumor necrosis factor-alpha (TNF-alpha). Subsequently, the expression of matrix metalloproteinase (MMP)-2 and MMP-9 were also inhibited by ghrelin injection. Ghrelin alleviates LV dysfunction and ventricular remodeling in post-MI rats. This suggests that the beneficial effects of ghrelin on CHF may result from an inhibition of the inflammatory response.

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.

Left ventricular remodeling after acute myocardial infarction: does eplerenone have an effect?

AIMS

Aldosterone antagonism reduces cardiovascular morbidity and mortality in patients with left ventricular (LV) systolic dysfunction and heart failure or diabetes after acute myocardial infarction (AMI). The mechanism of this effect is unclear. We performed a contrast-enhanced cardiac magnetic resonance study to assess the effects of eplerenone on LV remodeling after AMI.

METHODS

One hundred patients (mean age, 58.9 +/- 12 years; 77% male) with LV systolic dysfunction but without heart failure or diabetes were randomized to 24 weeks' double-blind treatment with eplerenone or placebo started 1 to 14 days after AMI. Contrast-enhanced cardiac magnetic resonance was performed, and plasma concentrations of matrix metalloproteinase-2 (MMP-2) and MMP-9 were measured before randomization and at 12 and 24 weeks.

RESULTS

Baseline LV ejection fraction was, by chance, significantly higher in eplerenone than in placebo-treated patients. Eplerenone had no effect on the primary end point (change in LV end-systolic volume index); after covariate adjustment, the primary end point fell by 6.1 +/- 2.7 mL/m2 with eplerenone compared to placebo (P = .027), and LV end-diastolic volume index fell by 7.5 +/- 3.4 mL/m2 (P = .031); eplerenone did not significantly influence LV ejection fraction. Eplerenone, after covariate adjustment, significantly decreased MMP-2 and increased MMP-9 over 24 weeks relative to placebo.

CONCLUSIONS

In a population of patients with AMI with high uptake of contemporary antiremodeling therapy, eplerenone provides modest incremental protection against LV remodeling, only after covariate adjustment.

Transcription factor decoys for activator protein-1 (AP-1) inhibit oxidative stress-induced proliferation and matrix metalloproteinases in rat cardiac fibroblasts

Activator protein-1 (AP-1), which is a transcription factor, is implicated in the transcriptional regulation of a wide range of genes that participate in cell proliferation and extracellular matrix production. This investigation was performed to test the hypothesis that transfection of cardiac fibroblasts (CFs) with sufficient amounts of decoy oligodeoxynucleotides (ODNs) containing the AP-1-binding site would result in binding to the transfactor AP-1, which would thereby prevent CF proliferation and matrix metalloproteinase (MMP) expression. CFs from Sprague-Dawley rat hearts were cultured and exposed to different concentrations of xanthine + xanthine oxidase (XXO) and AP-1 decoy ODNs. MMP expression was assayed after oxidative stress and transfection with AP-1 decoy ODNs by real-time quantitative polymerase chain reaction and Western blot. Cell growth was determined by the cell count. XXO significantly increased the DNA-binding activity of AP-1 in a dose-dependent manner. We found that transfection with AP-1 decoy ODNs strongly inhibited XXO-induced CF proliferation and MMP gene expression in vitro. Taken together, our data demonstrate that AP-1 is a key transcription factor that mediates CF proliferation and MMP synthesis under oxidative stress. Transfection with AP-1 decoy ODNs may be a novel strategy to inhibit CF proliferation and MMP synthesis.

Potential novel pharmacological therapies for myocardial remodelling

Left ventricular (LV) remodelling remains an important treatment target in patients after myocardial infarction (MI) and chronic heart failure (CHF). Accumulating evidence has supported the concept that beneficial effects of current pharmacological treatment strategies to improve the prognosis in these patients, such as angiotensin-converting enzyme (ACE) inhibition, angiotensin type 1 receptor blocker therapy, and beta-blocker therapy, are related, at least in part, to their effects on LV remodelling and dysfunction. However, despite modern reperfusion therapy after MI and optimized treatment of patients with CHF, LV remodelling is observed in a substantial proportion of patients and is associated with an adverse clinical outcome. These observations call for novel therapeutic strategies to prevent or even reverse cardiac remodelling. Recent insights from experimental studies have provided new targets for interventions to prevent or reverse LV remodelling, i.e. reduced endothelial nitric oxide (NO) synthase-derived NO availability, activation of cardiac and leukocyte-dependent oxidant stress pathways, inflammatory pathway activation, matrix-metalloproteinase activation, or stem cell transfer and delivery of novel paracrine factors. An important challenge in translating these observations from preclinical studies into clinical treatment strategies relates to the fact that clinical studies are designed on top of established pharmacological therapy, whereas most experimental studies have tested novel interventions without concomitant drug regimens such as ACE inhibitors or beta-blockers. Therefore, animal studies may overestimate the effect of potential novel treatment strategies on LV remodelling and dysfunction, since established pharmacological therapies may act, in part, via identical or similar signalling pathways. Nevertheless, preclinical studies provide essential information for identifying potential novel targets, and their potential drawbacks, and are required for developing novel clinical treatment strategies to prevent or reverse LV remodelling and dysfunction.

Alterations in circulating activin A, GDF-15, TGF-beta3 and MMP-2, -3, and -9 during one year of left ventricular reverse remodelling in patients operated for severe aortic stenosis

BACKGROUND

Patients with aortic stenosis (AS) develop left ventricular remodelling with cardiomyocyte hypertrophy and increased fibrosis. Following aortic valve replacement (AVR) reverse remodelling usually takes place.

AIMS

To examine circulating levels of members of the transforming growth factor (TGF) beta superfamily and matrix metalloproteinases (MMP), known to have important effects on hypertrophy and extracellular matrix, in patients operated for AS.

METHODS

Circulating levels of activin A, GDF-15, TGF-beta3, MMP-2, -3, and -9 were measured in twenty-two patients undergoing AVR preoperatively, and 2 days, six months and 12 months postoperatively. Echocardiography and a six minute walking test evaluated reverse remodelling and physical performance.

RESULTS

Activin A increased at six (1081.00+/-98.05 pg/ml, p<0.05) and twelve months (1263.09+/-141.43 pg/ml, p<0.05) compared to the preoperative value (855.00+/-76.30 pg/ml) and correlated negatively to physical performance. The preoperative value was also increased compared to controls (639.54+/-63.05 pg/ml, p<0.05). GDF-15, MMP-3 and -9 were all increased at two days postoperatively (p<0.05). MMP-3 correlated with left ventricular end diastolic dimension (p<0.05). MMP-2 did not change during the study period. TGF-beta3 was only slightly reduced at six months postoperatively.

CONCLUSION

The observed alteration in circulating levels of members of the TGF-beta superfamily and MMPs might play a role in the reverse remodelling process following AVR for AS.

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.

Circulating stromelysin-1 (MMP-3): a novel predictor of LV dysfunction, remodelling and all-cause mortality after acute myocardial infarction

INTRODUCTION

Changes to cardiac matrix are central to ventricular remodelling after acute MI and matrix metalloproteinase expression is implicated in this process. We investigated the temporal profile of MMP-3 and its relationship to LV dysfunction and prognosis following AMI.

METHODS

We studied 382 patients with AMI. Plasma MMP-3 was measured at 0-12, 12-24 h and for subsequent 24 h periods during admission. LV function (LVEF) was assessed by echocardiography pre-discharge and at a median of 148 days and clinical endpoints at a median of 313 days.

RESULTS

MMP-3 peaked prior to discharge thus pre-discharge levels were used in analyses. MMP-3 was associated with patient age (p<0.001), creatinine (p<0.001) and was higher in males (p<0.001) and hypertensives (p<0.001). MMP-3 inversely correlated with LVEF at follow-up (p=0.043), was higher in subjects with LVEF <40% (p=0.017) and in subjects with increasing EDV (p=0.017) or ESV (p=0.007) compared to those in whom volumes fell between visits. In the 58 patients reaching the endpoint of death or heart failure, MMP-3 was higher (p<0.001). On Kaplan-Meier analysis, subjects with levels above optimum cut off identified via ROC curves were more likely to suffer a clinical event (p=0.037).

CONCLUSION

MMP-3 is associated with left ventricular dysfunction, adverse left ventricular remodelling and prognosis after AMI.

Structural aspects of Golgi function

Since its discovery, the Golgi complex has attracted the attention of cell biologists because of its 'fashionable' morphology and central position within the secretory system of the cell. Here, we discuss how the three-dimensional architecture of the Golgi complex relates to its multiple functions in protein sorting and processing, and how an analysis of the morphology of the Golgi complex can help to provide an understanding of the mechanisms involved in transport through this unique organelle.