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

The role of matrix metalloproteinase-9 in cardiac remodeling and dysfunction and as a possible blood biomarker in heart failure

Heart failure (HF) is the leading cause of morbidity and mortality in cardiovascular diseases, being responsible for many hospitalizations annually. HF is considered a public health problem with significant economic and social impact, which makes searches essential for strategies that improve the ability to predict and diagnose HF. In this way, biomarkers can help in risk stratification for a more personalized approach to patients with HF. Preclinical and clinical evidence shows the participation of matrix metalloproteinase 9 (MMP-9) in the HF process. In this review, we will demonstrate the critical role that MMP-9 plays in cardiac remodeling and dysfunction. We will also show its importance as a blood biomarker in acute and chronic HF patients.

Clinical markers in heart failure: a narrative review

Heart failure is a complex clinical syndrome that is one of the causes of high mortality worldwide. Additionally, healthcare systems around the world are also being burdened by the aging population and subsequently, increasing estimates of patients with heart failure. As a result, it is crucial to determine novel ways to reduce the healthcare costs, rate of hospitalizations and mortality. In this regard, clinical biomarkers play a very important role in stratifying risk, determining prognosis or diagnosis and monitoring patient responses to therapy. This narrative review discusses the wide spectrum of clinical biomarkers, novel inventions of new techniques, their advantages and limitations as well as applications. As heart failure rates increase, cost-effective diagnostic tools such as B-type natriuretic peptide and N-terminal pro b-type natriuretic peptide are crucial, with emerging markers like neprilysin and cardiac imaging showing promise, though larger studies are needed to confirm their effectiveness compared with traditional markers.

Emerging biomarkers for the detection of cardiovascular diseases

Background

The prevalence of cardiovascular disease (CVD) has been continuously increasing, and this trend is projected to continue. CVD is rapidly becoming a significant public health issue. Every year there is a spike in hospital cases of CVD, a critical health concern in lower- and middle-income countries. Based on identification of novel biomarkers, it would be necessary to study and evaluate the diagnostic requirements or CVD to expedite early detection.

Main body

The literature review was written using a wide range of sources, such as well-known medical journals, electronic databases, manuscripts, texts, and other writings from the university library. After that, we analysed the specific markers of CVD and compiled a systematic review. A growing body of clinical research aims to identify people who are at risk for cardiovascular disease by looking for biomolecules. A small number of biomarkers have been shown to be useful and reliable in medicine. Biomarkers can be used for a variety of clinical applications, such as predicting heart disease risk, diagnosing disease, or predicting outcomes. As a result of the ability for a single molecule to act as a biomarker, its usefulness in medicine is expected to increase significantly.

Conclusions

Based on assessing the current trends in the application of CVD markers, we discussed and described the requirements for the application of CVD biomarkers in coronary heart disease, cerebrovascular disease, rheumatic heart disease, and other cardiovascular illnesses. Furthermore, the current review focuses on biomarkers for CVD and the procedures that should be considered to establish the comprehensive nature of the expression of biomarkers for cardiovascular illness.

Multidimensional Approach of Heart Failure Diagnosis and Prognostication Utilizing Cardiac Imaging with Biomarkers

Heart failure (HF) is a clinical syndrome caused by various etiologies that results in systolic and diastolic cardiac dysfunction with congestion. While evaluating HF and planning for treatment, physicians utilize various laboratory tests, including electrocardiography, diverse imaging tests, exercise testing, invasive hemodynamic evaluation, or endomyocardial biopsy. Among these, cardiac imaging modalities and biomarkers are the mainstays during HF diagnosis and treatment. Recent developments in non-invasive imaging modalities, such as echocardiography, computed tomography, magnetic resonance imaging, and nuclear imaging, have helped us understand the etiology, pathophysiology, and hemodynamics of HF, and determine treatment options and predict the outcomes. Due to the convenience of their use and potential impact on HF management, biomarkers are increasingly adopted in our clinical practice as well as research purpose. Natriuretic peptide is the most widely used biomarker for the diagnosis of HF, evaluation of treatment response, and prediction of future outcomes. Other cardiac biomarkers to evaluate the pathophysiological mechanisms of HF include myocardial injury, oxidative stress, inflammation, fibrosis, hypertrophy, and neurohormonal activation. Because HF results from complex cardiac disorders, it is essential to assess the disease status multidimensionally. The proper utilization of multimodality imaging and cardiac biomarkers can improve the quality of patient management and predict clinical outcomes in HF in the era of personalized medicine.

Biomarkers in Acute Heart Failure Syndromes: An Update

Heart failure is one of the leading healthcare problems in the world. Clinical data lacks sensitivity and specificity in the diagnosis of heart failure. Laboratory biomarkers are a non-invasive method of assessing suspected decompensated heart failure. Biomarkers such as natriuretic peptides have shown promising results in the management of heart failure. The literature does not provide comprehensive guidance in the utilization of biomarkers in the setting of acute heart failure syndrome. Many conditions that manifest with similar pathophysiology as acute heart failure syndrome may demonstrate positive biomarkers. The following is a review of biomarkers in heart failure, enlightening their role in diagnosis, prognosis and management of heart failure.

Matrix metalloproteinase-9 as a messenger in the cross talk between obstructive sleep apnea and comorbid systemic hypertension, cardiac remodeling, and ischemic stroke: a literature review

STUDY OBJECTIVES

OSA is a common sleep disorder. There is a strong link between sleep-related breathing disorders and cardiovascular and cerebrovascular diseases. Matrix metalloproteinase-9 (MMP-9) is a biological marker for extracellular matrix degradation, which plays a significant role in systemic hypertension, myocardial infarction and postmyocardial infarction heart failure, and ischemic stroke. This article reviews MMP-9 as an inflammatory mediator and a potential messenger between OSA and OSA-induced comorbidities.

METHODS

We reviewed the MEDLINE database (PubMed) for publications on MMP-9, OSA, and cardiovascular disease, identifying 1,592 studies and including and reviewing 50 articles for this work.

RESULTS

There is strong evidence that MMP-9 and tissue inhibitor of metalloproteinase-1 levels are elevated in patients with OSA (mainly MMP-9), systemic hypertension, myocardial infarction, and postmyocardial infarction heart failure. Our study showed variable results that could be related to the sample size or to laboratory methodology.

CONCLUSIONS

MMP-9 and its endogenous inhibitor, tissue inhibitor of metalloproteinase-1, are a common denominator in OSA, systemic hypertension, myocardial infarction, and heart failure. This characterization makes MMP-9 a target for developing novel selective inhibitors that can serve as adjuvant therapy in patients with OSA, which may ameliorate the cardiovascular and cerebrovascular mortality associated with OSA.

MMP9 inhibition increases autophagic flux in chronic heart failure

Increased matrix metalloprotease 9 (MMP9) after myocardial infarction (MI) exacerbates ischemia-induced chronic heart failure (CHF). Autophagy is cardioprotective during CHF; however, whether increased MMP9 suppresses autophagic activity in CHF is unknown. This study aimed to determine whether increased MMP9 suppressed autophagic flux and MMP9 inhibition increased autophagic flux in the heart of rats with post-MI CHF. Sprague-Dawley rats underwent either sham surgery or coronary artery ligation 6-8 wk before being treated with MMP9 inhibitor for 7 days, followed by cardiac autophagic flux measurement with lysosomal inhibitor bafilomycin A1. Furthermore, autophagic flux was measured in vitro by treating H9c2 cardiomyocytes with two independent pharmacological MMP9 inhibitors, salvianolic acid B (SalB) and MMP9 inhibitor-I, and CRISPR/cas9-mediated MMP9 genetic ablation. CHF rats showed cardiac infarct, significantly increased left ventricular end-diastolic pressure (LVEDP), and increased MMP9 activity and fibrosis in the peri-infarct areas of left ventricular myocardium. Measurement of the autophagic markers LC3B-II and p62 with lysosomal inhibition showed decreased autophagic flux in the peri-infarct myocardium. Treatment with SalB for 7 days in CHF rats decreased MMP9 activity and cardiac fibrosis but increased autophagic flux in the peri-infarct myocardium. As an in vitro corollary study, measurement of autophagic flux in H9c2 cardiomyocytes and fibroblasts showed that pharmacological inhibition or genetic ablation of MMP9 upregulates autophagic flux. These data are consistent with our observations that MMP9 inhibition upregulates autophagic flux in the heart of rats with CHF. In conclusion, the results in this study suggest that the beneficial outcome of MMP9 inhibition in pathological cardiac remodeling is in part mediated by improved autophagic flux.NEW & NOTEWORTHY This study elucidates that the improved cardiac extracellular matrix (ECM) remodeling and cardioprotective effect of matrix metalloprotease 9 (MMP9) inhibition in chronic heart failure (CHF) are via increased autophagic flux. Autophagy is cardioprotective; however, the mechanism of autophagy suppression in CHF is unknown. We for the first time demonstrated here that increased MMP9 suppressed cardiac autophagy and ablation of MMP9 increased cardiac autophagic flux in CHF rats. Restoring the physiological level of autophagy in the failing heart is a challenge, and our study addressed this challenge. The novelty and highlights of this report are as follows: 1) MMP9 regulates cardiomyocyte and fibroblast autophagy, 2) MMP9 inhibition protects CHF after myocardial infarction (MI) via increased cardiac autophagic flux, 3) MMP9 inhibition increased cardiac autophagy via activation of AMP-activated protein kinase (AMPK)α, Beclin-1, Atg7 pathway and suppressed mechanistic target of rapamycin (mTOR) pathway.

Established and Emerging Roles of Biomarkers in Heart Failure

Heart failure (HF) is a complex syndrome with an enormous societal burden in terms of cost, morbidity, and mortality. Natriuretic peptide testing is now widely used to support diagnosis, prognostication, and management of patients with HF and are incorporated into HF clinical practice guidelines. Beyond the natriuretic peptides, novel biomarkers may supplement traditional clinical and laboratory testing to improve understanding of the complex disease process of HF and possibly to personalize care for those affected through better individual phenotyping. In this review, we will discuss natriuretic peptides and the more novel biomarkers by dividing them into categories based on the major pathophysiologic pathways they represent. Given the complex physiology in HF, it is reasonable to expect that the future of biomarker testing lies in the application of multimarker testing panels, precision medicine to improve HF care delivery, and the use of biomarkers in proteomics and metabolomics to further improve HF care.

Left ventricular remodelling in chronic primary mitral regurgitation: implications for medical therapy

Surgical repair or replacement of the mitral valve is currently the only recommended therapy for severe primary mitral regurgitation. The chronic elevation of wall stress caused by the resulting volume overload leads to structural remodelling of the muscular, vascular and extracellular matrix components of the myocardium. These changes are initially compensatory but in the long term have detrimental effects, which ultimately result in heart failure. Understanding the changes that occur in the myocardium due to volume overload at the molecular and cellular level may lead to medical interventions, which potentially could delay or prevent the adverse left ventricular remodelling associated with primary mitral regurgitation. The pathophysiological changes involved in left ventricular remodelling in response to chronic primary mitral regurgitation and the evidence for potential medical therapy, in particular beta-adrenergic blockers, are the focus of this review.

Redefining biomarkers in heart failure

Heart failure (HF) is the end result of many different cardiac and non-cardiac abnormalities leading to a complex clinical entity. In this view, the use of biomarkers in HF should be deeply reconsidered; indeed, the same biomarker may carry a different significance in patients with preserved or reduced EF. The aim of this review is to reconsider the role of biomarkers in HF, based on the different clinical characteristics of this syndrome. The role of cardiac and non-cardiac biomarkers will be reviewed with respect of the different clinical manifestations of this syndrome.

Association between matrix metalloproteinase-9 and worsening heart failure events in patients with chronic heart failure

AIMS

Matrix metalloproteinase (MMP) is up-regulated during heart failure (HF) and influences ventricular remodeling. We hypothesized that disparity between MMP-9 and tissue inhibitors of MMP-1 (TIMP-1) results in clinical manifestations and is related to prognostic risk in patients with chronic HF.

METHODS AND RESULTS

Plasma levels of MMP-9, TIMP-1, and brain natriuretic peptide (BNP) were measured in 173 patients with chronic HF. Combined endpoints of worsening HF events were assessed during follow-up (median 109 months). MMP-9 and TIMP-1 levels and the MMP-9/TIMP-1 ratio increased with increasing severity of the New York Heart Association class (P for trend = 0.003, 0.011, and 0.005, respectively). Patients with HF events (n = 35) had significantly higher MMP-9 than those without HF events (P = 0.004). Kaplan-Meier analysis demonstrated a higher probability of HF events with high MMP-9 values (>23.2 ng/mL; P = 0.005). A multivariate Cox proportional hazard model showed that high MMP-9 values were an independent predictor of HF events (hazard ratio, 3.73; 95% confidence interval (CI), 1.03-13.46; P = 0.043). In patients with lower BNP levels (≤210 pg/mL), the adjusted hazard ratio for HF events was 3.63 (95% CI, 1.20-11.02; P = 0.023) among patients with high MMP-9 values compared with patients with low BNP and low MMP-9 values.

CONCLUSIONS

MMP-9 and TIMP-1 levels correlate with the severity of chronic HF. MMP-9 is a strong predictor of HF events, suggesting that a disparity between MMP-9 and TIMP-1 levels and increased MMP-9 levels may help predict HF events.

Beyond Natriuretic Peptides for Diagnosis and Management of Heart Failure

BACKGROUND

Heart failure (HF) is a complex syndrome with an enormous societal burden in terms of cost and morbidity and mortality. Natriuretic peptide (NP) testing is now widely used to support diagnosis, prognostication, and management of patients with HF, but NPs come with limitations, including vulnerability to the presence of obesity, atrial fibrillation, and renal dysfunction, for example. Beyond the NPs, novel biomarkers may supplement traditional clinical and laboratory testing to improve understanding of the complex disease process of HF, and possibly to personalize care for those affected through better individual phenotyping.

CONTENT

In this review we discuss novel biomarkers by dividing them into categories based on major pathophysiologic pathways they represent including myocardial stretch/stress, cardiac extracellular matrix remodeling, cardiomyocyte injury/death, oxidative stress, inflammation, neurohumoral activation, and renal dysfunction.

SUMMARY

Given the limitations of NPs, along with the complex physiology in HF, it is logical to consider utilization of novel biomarkers providing orthogonal biological and clinical information. Several novel HF biomarkers have shown promise but have substantial expectations to meet before being used clinically. Nonetheless, it is reasonable to expect the future lies in the application of multibiomarker panels for the improvement in management of HF and the personalization of care.

Ablation of Matrix Metalloproteinase-9 Prevents Cardiomyocytes Contractile Dysfunction in Diabetics

Elevated expression and activity of matrix metalloproteinase-9 (MMP9) and decreased contractility of cardiomyocytes are documented in diabetic hearts. However, it is unclear whether MMP is involved in the regulation of contractility of cardiomyocytes in diabetic hearts. In the present study, we tested the hypothesis that MMP9 regulates contractility of cardiomyocytes in diabetic hearts, and ablation of MMP9 prevents impaired contractility of cardiomyocytes in diabetic hearts. To determine the specific role of MMP9 in cardiomyocyte contractility, we used 12–14 week male WT (normoglycemic sibling of Akita), Akita, and Ins^2+∕−/MMP9^−∕− (DKO) mice. DKO mice were generated by cross-breeding male Ins2^+∕− Akita (T1D) with female MMP9 knockout (MMP9^−∕−) mice. We isolated cardiomyocytes from the heart of the above three groups of mice and measured their contractility and calcium transients. Moreover, we determined mRNA and protein levels of sarco-endoplasmic reticulum calcium ATPase-2a (SERCA-2a), which is involved in calcium handling during contractility of cardiomyocytes in WT, Akita, and DKO hearts using QPCR, Western blotting and immunoprecipitation, respectively. Our results revealed that in Akita hearts where increased expression and activity of MMP9 is reported, the rates of shortening and re-lengthening (±dL/dt) of cardiomyocytes were decreased, time to 90% peak height and baseline during contractility was increased, rate of calcium decay was increased, and calcium transient was decreased as compared to WT cardiomyocytes. However, these changes in Akita were blunted in DKO cardiomyocytes. The molecular analyses of SERCA-2a in the hearts showed that it was downregulated in Akita as compared to WT but was comparatively upregulated in DKO. These results suggest that abrogation of MMP9 gene prevents contractility of cardiomyocytes, possibly by increasing SERCA-2a and calcium transients. We conclude that MMP9 plays a crucial role in the regulation of contractility of cardiomyocytes in diabetic hearts.

Circulating multimarker profile of patients with symptomatic heart failure supports enhanced fibrotic degradation and decreased angiogenesis

BACKGROUND

Heart failure (HF) involves myocardial fibrosis and dysregulated angiogenesis.

OBJECTIVE

We explored whether biomarkers of fibrosis and angiogenesis correlate with HF severity.

METHODS

Biomarkers of fibrosis [procollagen types I and III (PIP and P3NP), carboxyterminal-telopeptide of type I collagen (ICTP), matrix metalloproteases (MMP2 and MMP9), tissue inhibitor of MMP1 (TIMP1)]; and angiogenesis [placental growth factor (PGF), vascular endothelial growth factor (VEGF), soluble Fms-like tyrosine kinase-1 (sFlt1)] were measured in 52 HF patients and 19 controls.

RESULTS

P3NP, ICTP, MMP2, TIMP1, PGF, and sFlt1 levels were elevated in HF, while PIP/ICTP, PGF/sFlt1, and VEGF/sFlt1 ratios were reduced. PIP/ICTP, MMP-9/TIMP1, and VEGF/sFlt1 ratios were lowest among patients with severe HF.

CONCLUSIONS

Severe HF is associated with collagen breakdown and reduced angiogenesis. A multimarker approach may guide therapeutic targeting of fibrosis and angiogenesis in HF.

MMP-9 in atrial remodeling in patients with atrial fibrillation

INTRODUCTION

Atrial fibrillation (AF) is the most common arrhythmia and is associated with significant morbidity and mortality. The impact of matrix metalloproteinases (MMPs) on structural atrial remodeling and sustainment of AF in patients with persistent and permanent AF is unresolved.

OBJECTIVES

The aim was to evaluate MMP-9 and its tissue inhibitor-1 (TIMP-1) as markers of atrial remodeling in patients with persistent AF (PAF) who underwent electrical cardioversion (ECV) and in patients with permanent AF (continuous AF, CAF).

PATIENTS AND METHODS

Plasma levels of MMP-9 and TIMP-1, clinical findings, and echocardiographic parameters were evaluated in 39 patients with AF and in 14 controls with sinus rhythm.

RESULTS

The concentrations of MMP-9 were significantly higher in patients with PAF and CAF compared to controls. There was a significant increase of MMP-9 after ECV in the persistent AF group. The values of TIMP-1 were not significantly different between the groups. In patients with AF, MMP-9 levels were positively related to posterior wall thickness of the LV (r=0.356, P=0.049) and body mass index (r=0.367, P=0.046).

CONCLUSION

Elevated levels of MMP-9 were related to the occurrence and maintenance of AF. This suggests that MMP-9 can be a marker of atrial remodeling in patients with AF. Regulation of the extracellular collagen matrix might be a potential therapeutic target in AF.

Prognosis of new-onset heart failure outpatients and collagen biomarkers

BACKGROUND

Prognosis of heart failure patients has been defined in hospital-based or retrospective studies. This study aimed to characterize prognosis of outpatients with new-onset preserved or reduced ejection fraction heart failure; to explore the role of collagen turnover biomarkers (MMP2, MMP9, TIMP1) in predicting prognosis; and to analyse their relationship with echocardiographic parameters and final diagnosis.

METHODS

This is an observational, prospective, longitudinal study. Outpatients with new-onset heart failure symptoms referred to a one-stop clinic were included. Echocardiography and biomarkers plasma levels determination were performed at the inclusion. A prospective follow-up was conducted to report cardiovascular events. The discriminant analysis was applied to identify the parameters related to cardiovascular outcomes.

RESULTS

A total of 172 patients (75 ± 9 years) were included, 67% with heart failure (64% preserved and 36% with reduced ejection fraction). During follow-up (median 34.5 months), 32.6% had at least one cardiovascular event and 9.9% died. Heart failure groups showed no differences in cardiovascular outcomes with a higher rate of events than nonheart failure patients. MMP2 and TIMP1 were correlated with diastolic dysfunction (Rho 0.349 and 0.294, P < 0.001). In the discriminant analysis, the combination of biomarkers with clinical, biochemical and echocardiographic parameters was useful to predict cardiovascular outcomes (AUC ROC 0.806, Wilks lambda 0.7688, P < 0.001).

CONCLUSIONS

Prognosis of outpatients with new-onset heart failure symptoms is comparable between heart failure with preserved or reduced subgroups. The addition of biomarkers specially MMP2 and high sensitive troponin I to other clinical, biochemical and echocardiographic variables can predict cardiovascular prognosis at the time of diagnosis.

Dysregulation of Mfn2 and Drp-1 proteins in heart failure

Therapeutic approaches for cardiac regenerative mechanisms have been explored over the past decade to target various cardiovascular diseases (CVD). Structural and functional aberrations of mitochondria have been observed in CVD. The significance of mitochondrial maturation and function in cardiomyocytes is distinguished by their attribution to embryonic stem cell differentiation into adult cardiomyocytes. An abnormal fission process has been implicated in heart failure, and treatment with mitochondrial division inhibitor 1 (Mdivi-1), a specific inhibitor of dynamin related protein-1 (Drp-1), has been shown to improve cardiac function. We recently observed that the ratio of mitofusin 2 (Mfn2; a fusion protein) and Drp-1 (a fission protein) was decreased during heart failure, suggesting increased mitophagy. Treatment with Mdivi-1 improved cardiac function by normalizing this ratio. Aberrant mitophagy and enhanced oxidative stress in the mitochondria contribute to abnormal activation of MMP-9, leading to degradation of the important gap junction protein connexin-43 (Cx-43) in the ventricular myocardium. Reduced Cx-43 levels were associated with increased fibrosis and ventricular dysfunction in heart failure. Treatment with Mdivi-1 restored MMP-9 and Cx-43 expression towards normal. In this review, we discuss mitochondrial dynamics, its relation to MMP-9 and Cx-43, and the therapeutic role of fission inhibition in heart failure.

Cardiac biomarkers in heart failure

BACKGROUND

Heart failure is a syndrome characterized by the inability of the heart to meet the body's circulatory demands. Heart failure is a growing health issue worldwide and the prevalence of heart failure is expected to rise as populations age. Therapies and interventions for a variety of cardiac conditions continue to advance and biomarkers will play an increasing role in patient management.

METHODS

This is a review of the clinical research in blood based biomarkers for diagnosis, prognosis and therapeutic guidance of heart failure. The focus of this review is biomarkers that are currently available for clinical measurement, and their current and potential for applications for managing heart failure patients.

RESULTS

The various biologic pathways and physiologic processes of heart failure biomarkers represent a host of different including inflammation, remodeling, strain, neurohormonal activation, metabolism and cardiac myocyte injury. The clinical characteristics and applications of each heart failure biomarker are discussed.

CONCLUSION

As populations age and effective treatments and interventions for coronary artery disease improve, heart failure will increase in incidence and prevalence. Blood biomarkers will play an increasing role in the early diagnosis, therapeutic monitoring and management of heart failure patients in the future.

Generating double knockout mice to model genetic intervention for diabetic cardiomyopathy in humans

Diabetes is a rapidly increasing disease that enhances the chances of heart failure twofold to fourfold (as compared to age and sex matched nondiabetics) and becomes a leading cause of morbidity and mortality. There are two broad classifications of diabetes: type1 diabetes (T1D) and type2 diabetes (T2D). Several mice models mimic both T1D and T2D in humans. However, the genetic intervention to ameliorate diabetic cardiomyopathy in these mice often requires creating double knockout (DKO). In order to assess the therapeutic potential of a gene, that specific gene is either overexpressed (transgenic expression) or abrogated (knockout) in the diabetic mice. If the genetic mice model for diabetes is used, it is necessary to create DKO with transgenic/knockout of the target gene to investigate the specific role of that gene in pathological cardiac remodeling in diabetics. One of the important genes involved in extracellular matrix (ECM) remodeling in diabetes is matrix metalloproteinase-9 (Mmp9). Mmp9 is a collagenase that remains latent in healthy hearts but induced in diabetic hearts. Activated Mmp9 degrades extracellular matrix (ECM) and increases matrix turnover causing cardiac fibrosis that leads to heart failure. Insulin2 mutant (Ins2+/-) Akita is a genetic model for T1D that becomes diabetic spontaneously at the age of 3-4 weeks and show robust hyperglycemia at the age of 10-12 weeks. It is a chronic model of T1D. In Ins2+/- Akita, Mmp9 is induced. To investigate the specific role of Mmp9 in diabetic hearts, it is necessary to create diabetic mice where Mmp9 gene is deleted. Here, we describe the method to generate Ins2+/-/Mmp9-/- (DKO) mice to determine whether the abrogation of Mmp9 ameliorates diabetic cardiomyopathy.

Role of various proteases in cardiac remodeling and progression of heart failure

It is believed that cardiac remodeling due to geometric and structural changes is a major mechanism for the progression of heart failure in different pathologies including hypertension, hypertrophic cardiomyopathy, dilated cardiomyopathy, diabetic cardiomyopathy, and myocardial infarction. Increases in the activities of proteolytic enzymes such as matrix metalloproteinases, calpains, cathepsins, and caspases contribute to the process of cardiac remodeling. In addition to modifying the extracellular matrix, both matrix metalloproteinases and cathepsins have been shown to affect the activities of subcellular organelles in cardiomyocytes. The activation of calpains and caspases has been identified to induce subcellular remodeling in failing hearts. Proteolytic activities associated with different proteins including caspases, calpain, and the ubiquitin-proteasome system have been shown to be involved in cardiomyocyte apoptosis, which is an integral part of cardiac remodeling. This article discusses and compares how the activities of various proteases are involved in different cardiac abnormalities with respect to alterations in apoptotic pathways, cardiac remodeling, and cardiac dysfunction. An imbalance appears to occur between the activities of some proteases and their endogenous inhibitors in various types of hypertrophied and failing hearts, and this is likely to further accentuate subcellular remodeling and cardiac dysfunction. The importance of inhibiting the activities of both extracellular and intracellular proteases specific to distinct etiologies, in attenuating cardiac remodeling and apoptosis as well as biochemical changes of subcellular organelles, in heart failure has been emphasized. It is suggested that combination therapy to inhibit different proteases may prove useful for the treatment of heart failure.

Matrix metalloproteinases 2 and 9 as diagnostic markers in the progression to Chagas cardiomyopathy

BACKGROUND

Infection with the Trypanosoma cruzi parasite is endemic in parts of Central and South America. Approximately 30% of those infected develop Chagas cardiomyopathy, the most common cause of heart failure in this region. No suitable biomarker is available that reflects the evolution of the disease. Although there is substantial evidence of a strong inflammatory reaction following infection that could activate matrix metalloproteinases (MMPs), their role in the development of Chagas cardiomyopathy is unknown.

METHODS

A cross-sectional study was conducted in Bucaramanga, Colombia, from 2002 to 2006, including 144 patients at different stages of Chagas disease and 44 control patients. The potential enzyme activities of MMP-2 and MMP-9 in plasma samples were determined by gelatin zymography. Clinical data including T cruzi serology, electrocardiograms, and echocardiograms were recorded for all patients.

RESULTS

Densitometric analysis of potential enzyme activities in plasma samples showed a significant increase of 72-kd MMP-2 (P < .001) and 92-kd MMP-9 (P < .001) in T cruzi seropositive patients compared with control subjects. Matrix metalloproteinase 9 showed significantly increased activity in patients with abnormal electrocardiogram (P < .004) and with dilated cardiomyopathy compared (P < .001) with controls. Analysis of the MMP-2 and MMP-9 results in relation to clinical data revealed that abnormal heart relaxation correlated positively with high MMP-2 levels in patients with dilated cardiomyopathy (r = 0.75, P < .01).

CONCLUSIONS

Plasma MMP-2 and MMP-9 both appear to be useful biomarkers for detecting the advent and progression of cardiomyopathy in T cruzi-infected individuals.

Cardiac stem cell niche, MMP9, and culture and differentiation of embryonic stem cells

Embryonic stem cells (ESC) are totipotent, self-renewing, and clonogenic, having potential to differentiate into a wide variety of cell types. Due to regenerative capability, it has tremendous potential for treating myocardial infarction (death of myocardial tissue) and type 1 diabetes (death of pancreatic beta cells). Understanding the components regulating ESC differentiation is the key to unlock the regenerative potential of ESC-based therapies. Both the stiffness of extracellular matrix (ECM) and surrounding niche/microenvironment play pivotal roles in ESC differentiation. Matrix metalloproteinase-9 (MMP9) induces fibrosis that causes stiffness of the ECM and impairs differentiation of cardiac stem cells into cardiomyocytes. Here, we describe the method of ESC culture and differentiation, and the expression of MMP9 and its inhibitor, tissue inhibitor of metalloproteinase-4 (TIMP4) in differentiating ESC.

Aldosterone and cardiovascular disease: the heart of the matter

Aldosterone contributes to the endocrine basis of heart failure, and studies on cardiac aldosterone signaling have reinforced its value as a therapeutic target. Recent focus has shifted to new roles of aldosterone that appear to depend on coexisting pathologic stimuli, cell type, and disease etiology. This review evaluates recent advances in mechanisms underlying aldosterone-induced cardiac disease and highlights the interplay between aldosterone and Ca(2+)/calmodulin dependent protein kinase II, whose hyperactivity during heart failure contributes to disease progression. Increasing evidence implicates aldosterone in diastolic dysfunction, and there is a need to develop more targeted therapeutics such as aldosterone synthase inhibitors and molecularly specific antioxidants. Despite accumulating knowledge, many questions still persist and will likely dictate areas of future research.

Cardiomyopathy in the dystrophin/utrophin-deficient mouse model of severe muscular dystrophy is characterized by dysregulation of matrix metalloproteinases

Cardiomyopathy is a significant component in Duchenne muscular dystrophy. Although mdx mice are deficient in dystrophin, they only develop mild indicators of cardiomyopathy before 1year-of-age, making therapeutic investigations using this model lengthy. In contrast, mdx mice also lacking utrophin (utrn(-/-);mdx) show severely reduced cardiac contractile function and histological indicators of cardiomyopathy by 8-10weeks-of-age. Here we demonstrate that utrn(-/-);mdx mice show a similar pattern of cardiac damage to that in dystrophic patients. Matrix metalloproteinases required for ventricular remodeling during the evolution of heart failure are upregulated in utrn(-/-);mdx mice concurrent with the onset of cardiac pathology by 10weeks-of-age. Matrix metalloproteinase activity is further dysregulated due to reduced levels of endogenous tissue inhibitors and co-localizes with fibroblasts and collagen I-containing scars. utrn(-/-);mdx mice are therefore a very useful model for investigating potential cardiac therapies.

Ablation of MMP9 induces survival and differentiation of cardiac stem cells into cardiomyocytes in the heart of diabetics: a role of extracellular matrix

The contribution of extracellular matrix (ECM) to stem cell survival and differentiation is unequivocal, and matrix metalloproteinase-9 (MMP9) induces ECM turn over; however, the role of MMP9 in the survival and differentiation of cardiac stem cells is unclear. We hypothesize that ablation of MMP9 enhances the survival and differentiation of cardiac stem cells into cardiomyocytes in diabetics. To test our hypothesis, Ins2(+/-) Akita, C57 BL/6J, and double knock out (DKO: Ins2(+/-)/MMP9(-/-)) mice were used. We created the DKO mice by deleting the MMP9 gene from Ins2(+/-). The above 3 groups of mice were genotyped. The activity and expression of MMP9 in the 3 groups were determined by in-gel gelatin zymography, Western blotting, and confocal microscopy. To determine the role of MMP9 in ECM stiffness (fibrosis), we measured collagen deposition in the histological sections of hearts using Masson's trichrome staining. The role of MMP9 in cardiac stem cell survival and differentiation was determined by co-immunoprecipitation (co-IP) of MMP9 with c-kit (a marker of stem cells) and measuring the level of troponin I (a marker of cardiomyocytes) by confocal microscopy in the 3 groups. Our results revealed that ablation of MMP9 (i) reduces the stiffness of ECM by decreasing collagen accumulation (fibrosis), and (ii) enhances the survival (elevated c-kit level) and differentiation of cardiac stem cells into cardiomyocytes (increased troponin I) in diabetes. We conclude that inhibition of MMP9 ameliorates stem cell survival and their differentiation into cardiomyocytes in diabetes.

Emerging biomarkers in heart failure

BACKGROUND

Until recently, biomarker testing in heart failure (HF) syndromes has been viewed as an elective supplement to diagnostic evaluation of patients suspected to suffer from this condition. This approach to the use of biomarker testing contrasts with other cardiovascular diagnoses such as acute myocardial infarction, for which biomarkers are integral to disease process definition, risk stratification, and in some cases treatment decision making.

CONTENT

In this review we consider various perspectives on the evaluation of biomarkers in HF. In addition, we examine recent advances in the understanding of established biomarkers in HF (such as the natriuretic peptides), the elucidation of novel biomarkers potentially useful for the evaluation and management of patients with HF, and the growing understanding of important and relevant comorbidities in HF. We also review candidate biomarkers from a number of classes: (a) myocyte stretch, (b) myocyte necrosis, (c) systemic inflammation, (d) oxidative stress, (e) extracellular matrix turnover, (f) neurohormones, and (g) biomarkers of extracardiac processes, such as renal function.

SUMMARY

Novel applications of established biomarkers of HF as well as elucidation and validation of emerging assays for HF syndromes have collectively led to a growing interest in the more widespread use of such testing in patients affected by the diagnosis.

Novel biomarkers in human terminal heart failure and under mechanical circulatory support

This review summarizes recent findings on novel biochemical plasma biomarkers in terminal heart failure patients, which might predict an advanced mortality risk or even recovery. Moreover, we discussed the regulation of these heart failure-related biomarkers under mechanical circulatory support.

Circulating serum matrix metalloproteinase-3 and metalloproteinase-9 are not associated with echocardiographic parameters of diastolic function in asymptomatic type 2 diabetic patients

Serum concentrations of matrix metalloproteinase (MMP) 3 and MMP9 were evaluated in 82 asymptomatic type 2 diabetes mellitus patients without cardiovascular complications and in 41 non-diabetic control subjects. In the asymptomatic diabetic patients, the correlations of these concentrations with diabetes duration, selected biochemical parameters such as glycated haemoglobin (HbA(1c)), and echocardiographic parameters of diastolic function were also assessed. Pulsed and tissue Doppler echocardiography was performed in the two groups. Mean ± SD age was 61 ± 6 years for the asymptomatic diabetic patients and 61 ± 5 years for controls. Mean ± SD concentrations of MMP3 and MMP9 were significantly higher in the asymptomatic diabetic patients (67.5 ± 10.4 and 77.8 ± 28.8 μg/l, respectively) than in controls (47.2 ± 6.1 and 51.1 ± 13.7 μg/l, respectively). In the asymptomatic diabetic patients, MMP3 correlated only with albuminuria (r = 0.341) and MMP9 only with HbA(1c) (r = 0.262); neither MMP was correlated with echocardiographic parameters of diastolic function. Thus, in asymptomatic type 2 diabetic patients without cardiovascular complications, serum MMP3 and MMP9 were elevated, MMP9 was associated with HbA(1c) and MMP3 was associated with albuminuria, however, MMP3 and MMP9 were not associated with echocardiographic parameters of diastolic function.