A quantitative gene expression profile of matrix metalloproteinases (MMPS) and their inhibitors (TIMPS) in the myocardium of patients with deteriorating heart failure requiring left ventricular assist device support

Screening of Lipid Metabolism-Related Gene Diagnostic Signature for Patients With Dilated Cardiomyopathy

Background

Dilated cardiomyopathy (DCM) is characterized by enlarged ventricular dimensions and systolic dysfunction and poor prognosis. Myocardial lipid metabolism appears abnormal in DCM. However, the mechanism of lipid metabolism disorders in DCM remains unclear.

Methods

A gene set variation analysis (GSVA) were performed to estimate pathway activity related to DCM progression. Three datasets and clinical data downloaded from the Gene Expression Omnibus (GEO), including dilated cardiomyopathy and donor hearts, were integrated to obtain gene expression profiles and identify differentially expressed genes related to lipid metabolism. GO enrichment analyses of differentially expressed lipid metabolism-related genes (DELs) were performed. The clinical information used in this study were obtained from GSE21610 dataset. Data from the EGAS00001003263 were used for external validation and our hospital samples were also tested the expression levels of these genes through RT-PCR. Subsequently, logistic regression model with the LASSO method for DCM prediction was established basing on the 7 DELs.

Results

GSVA analysis showed that the fatty acid metabolism was closely related to DCM progression. The integrated dataset identified 19 DELs, including 8 up-regulated and 11 down-regulated genes. A total of 7 DELs were identified by further external validation of the data from the EGAS00001003263 and verified by RT-PCR. By using the LASSO model, 6 genes, including CYP2J2, FGF1, ETNPPL, PLIN2, LPCAT3, and DGKG, were identified to construct a logistic regression model. The area under curve (AUC) values over 0.8 suggested the good performance of the model.

Conclusion

Integrated bioinformatic analysis of gene expression in DCM and the effective logistic regression model construct in our study may contribute to the early diagnosis and prevention of DCM in people with high risk of the disease.

Sex differences in circulating proteins in heart failure with preserved ejection fraction

BACKGROUND

Many patients with heart failure with preserved ejection fraction (HFpEF) are women. Exploring mechanisms underlying the sex differences may improve our understanding of the pathophysiology of HFpEF. Studies focusing on sex differences in circulating proteins in HFpEF patients are scarce.

METHODS

A total of 415 proteins were analyzed in 392 HFpEF patients included in The Metabolic Road to Diastolic Heart Failure: Diastolic Heart Failure study (MEDIA-DHF). Sex differences in these proteins were assessed using adjusted logistic regression analyses. The associations between candidate proteins and cardiovascular (CV) death or CV hospitalization (with sex interaction) were assessed using Cox regression models.

RESULTS

We found 9 proteins to be differentially expressed between female and male patients. Women expressed more LPL and PLIN1, which are markers of lipid metabolism; more LHB, IGFBP3, and IL1RL2 as markers of transcriptional regulation; and more Ep-CAM as marker of hemostasis. Women expressed less MMP-3, which is a marker associated with extracellular matrix organization; less NRP1, which is associated with developmental processes; and less ACE2, which is related to metabolism. Sex was not associated with the study outcomes (adj. HR 1.48, 95% CI 0.83-2.63), p = 0.18.

CONCLUSION

In chronic HFpEF, assessing sex differences in a wide range of circulating proteins led to the identification of 9 proteins that were differentially expressed between female and male patients. These findings may help further investigations into potential pathophysiological processes contributing to HFpEF.

Activation of ALDH2 attenuates high glucose induced rat cardiomyocyte fibrosis and necroptosis

Necroptosis is one of a regulated programmed death mode, fibrosis is closely related with cell death. It has been reported that inhibition of necroptosis can play the protective role in cardiac ischemia and reperfusion injury, stroke and other diseases, but the mechanisms of aldehyde dehydrogenases 2 (ALDH2) against high glucose induced neonatal rat ventricular primary cardiomyocytes fibrosis and necroptosis had not been elucidated clearly. This study was to observe the effect of ALDH2 on high glucose (HG) induced myocardial fibrosis and necroptosis in primary rat cardiomyocytes model. In contrast to normal glucose group, in HG group, with the decreases of ALDH2 activity, mRNA and protein levels, the cardiomyocytes viability was decreased, reactive oxygen species (ROS), the inflammation factors - tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-1β (IL-1β) levels, collagen I (col I) and col III mRNA expressions and tissue inhibitors of matrix metalloproteinase 4 (TIMP4) protein expression were increased, while matrix metalloproteinase 14 (MMP14) protein level, the ratio of MMP14/TIMP4 were decreased, and the necroptosis key factors - the receptor interacting protein 1 (RIP1), RIP3 and mixed lineage kinase domain-like protein (MLKL) at mRNA and protein expressions were increased, the inflammasome core proteins - NLRP3 and ASC protein expressions were also increased, the apoptosis rate and necrosis rate were also increased. When the cardiomyocytes were treated with Alda-1 (the ALDH2 agonist) in HG intervention, the cell viability, ALDH2 activity, mRNA and protein levels, MMP14 protein level, the ratio of MMP14/TIMP4 were higher, ROS and TNF-α, IL-6, IL-1β levels, RIP1, RIP3, MLKL, NLRP3 and ASC expressions, col I and col III, TIMP4 expressions, the apoptosis rate and necrosis rate were lower than in HG group. Daidzin, the antagonist of ALDH2 abolished the role of Alda-1. In summary, ALDH2 maybe is a key regulator in high glucose induced cardiomyocytes injury. Activation of ALDH2 prevented the happening of fibrosis, apoptosis and necroptosis in high glucose induced primary cardiomyocytes injury model, the protective effects were related to the inhibiting of oxidative stress and inflammation, changing of MMP14 and TIMP4, then inhibiting the happening of fibrosis, apoptosis and necroptosis. These findings advance our understanding of the intensive mechanisms of ALDH2's cardioprotection, and provide the targeted basis for clinical diabetes treatment.

Cell-Specific Pathways Supporting Persistent Fibrosis in Heart Failure

BACKGROUND

Only limited data exist describing the histologic and noncardiomyocyte function of human myocardium in end-stage heart failure (HF).

OBJECTIVES

The authors sought to determine changes in noncardiomyocyte cellular activity in patients with end-stage HF after left ventricular assist device (LVAD)-induced remodeling to identify mechanisms impeding recovery.

METHODS

Myocardium was obtained from subjects undergoing LVAD placement and/or heart transplantation. Detailed histological analyses were performed, and, when feasible, mononuclear cells were isolated from fresh, dissociated myocardium for quantitative reverse transcription polymerase chain reaction studies. Echocardiographic and catheterization data were obtained during routine care.

RESULTS

Sixty-six subjects were enrolled; 54 underwent 8.0 ± 1.2 months of LVAD unloading. Despite effective hemodynamic unloading and remodeling, there were no differences after LVAD use in capillary density (0.78 ± 0.1% vs. 0.9 ± 0.1% capillary area; n = 42 and 28, respectively; p = 0.40), cardiac fibrosis (25.7 ± 2.4% vs. 27.9 ± 2.4% fibrosis area; n = 44 and 31, respectively; p = 0.50), or macrophage density (80.7 ± 10.4 macrophages/mm² vs. 108.6 ± 15 macrophages/mm²; n = 33 and 28, respectively; p = 0.1). Despite no change in fibrosis or myofibroblast density (p = 0.40), there was a 16.7-fold decrease (p < 0.01) in fibroblast-specific collagen expression. Furthermore, there was a shift away from pro-fibrotic/alternative pro-fibrotic macrophage signaling after LVAD use.

CONCLUSIONS

Despite robust cardiac unloading, capillary density and fibrosis are unchanged compared with loaded hearts. Fibroblast-specific collagen expression was decreased and might be due to decreased stretch and/or altered macrophage polarization. Dysfunctional myocardium may persist, in part, from ongoing inflammation and poor extracellular matrix remodeling. Understanding these changes could lead to improved therapies for HF.

Maternal nicotine exposure leads to decreased cardiac protein disulfide isomerase and impaired mitochondrial function in male rat offspring

Smoking throughout pregnancy can lead to complications during gestation, parturition and neonatal development. Thus, nicotine replacement therapies are a popular alternative thought to be safer than cigarettes. However, recent studies in rodents suggest that fetal and neonatal nicotine exposure alone results in cardiac dysfunction and high blood pressure. While it is well known that perinatal nicotine exposure causes increased congenital abnormalities, the mechanisms underlying longer-term deficits in cardiac function are not completely understood. Recently, our laboratory demonstrated that nicotine impairs placental protein disulfide isomerase (PDI) triggering an increase in endoplasmic reticulum stress, leading us to hypothesize that this may also occur in the heart. At 3 months of age, nicotine-exposed offspring had 45% decreased PDI levels in the absence of endoplasmic reticulum stress. Given the association of PDI and superoxide dismutase enzymes, we further observed that antioxidant superoxide dismutase-2 levels were reduced by 32% in these offspring concomitant with a 26-49% decrease in mitochondrial complex proteins (I, II, IV and V) and tissue inhibitor of metalloproteinase-4, a critical matrix metalloprotease for cardiac contractility and health. Collectively, this study suggests that perinatal nicotine exposure decreases PDI, which can promote oxidative damage and mitochondrial damage, associated with a premature decline in cardiac function.

Progressive Aortic Dilation Is Regulated by miR-17-Associated miRNAs

BACKGROUND

Patients with a bicuspid aortic valve (BAV) are at increased risk for progressive aortic dilation associated with extracellular matrix (ECM) degradation by matrix metalloproteinases (MMP). However, the mechanisms responsible for initiating this process are unknown. In the heart, MMP activity is regulated by micro-ribonucleic acid-17 (miR-17)-related downregulation of tissue inhibitors of metalloproteinases (TIMP); a similar process may exist in the aorta.

OBJECTIVES

This study sought to ascertain whether aortic matrix degradation in BAV patients progresses by miR-17-related miRNA regulation of TIMP-MMP.

METHODS

To eliminate confounding patient-related factors, severely dilated and less dilated aortic tissue samples were collected from 12 BAV patients. Gene and protein expression levels were evaluated in paired tissue samples from the same patient and were compared to aortic samples from 16 patients with aortas that appeared to be normal.

RESULTS

Gene expression analyses confirmed increased expression of miR-17-related miRNAs in less dilated compared with severely dilated tissue from the same patient or normal aortic sample. TIMP-1, -2, and -3 were significantly decreased, and MMP2 activity was significantly increased in less dilated samples, suggesting that this normal-looking tissue was in the early stages of ECM degradation. Smooth muscle cells isolated from normal or BAV aortas transfected with an miR-17 mimic had decreased TIMP-1 and -2 expression and increased MMP2 activity, whereas the opposite effects were seen with an miR-17 inhibitor, suggesting that miR-17 may control the TIMP-MMP balance in these tissues. Luciferase reporter assays demonstrated that miR-17 regulated TIMP-1 and -2 expression.

CONCLUSIONS

Our in vitro and in vivo studies taken together confirm that miR-17 directly regulates TIMP-1 and -2. Less dilated aortic BAV tissue may be in the initial stages of dilation under the control of miR-17-related miRNAs. New therapies that inhibit these miRNAs may prevent aortic dilation.

Temporal cardiac remodeling post-myocardial infarction: dynamics and prognostic implications in personalized medicine

Despite dramatic improvements in short-term mortality rates following myocardial infarction (MI), long-term survival for MI patients who progress to heart failure remains poor. MI occurs when the left ventricle (LV) is deprived of oxygen for a sufficient period of time to induce irreversible necrosis of the myocardium. The LV response to MI involves significant tissue, cellular, and molecular level modifications, as well as substantial hemodynamic changes that feedback negatively to amplify the response. Inflammation to remove necrotic myocytes and fibroblast activation to form a scar are key wound healing responses that are highly variable across individuals. Few biomarkers of early remodeling stages are currently clinically adopted. The discovery of underlying pathophysiological mechanisms and associated novel biomarkers has the potential of improving prognostic capability and therapeutic monitoring. Combining these biomarkers with other prominent ones could constitute a powerful diagnostic and prognostic tool that directly reflects the pathophysiological remodeling of the LV. Understanding temporal remodeling at the tissue, cellular, and molecular level and its link to a well-defined set of biomarkers at early stages post-MI is a prerequisite for improving personalized care and devising more successful therapeutic interventions. Here we summarize the integral mechanisms that occur during early cardiac remodeling in the post-MI setting and highlight the most prominent biomarkers for assessing disease progression.

Canopy 2 attenuates the transition from compensatory hypertrophy to dilated heart failure in hypertrophic cardiomyopathy

AIMS

A mismatch between adequate angiogenesis and overgrowth of myocytes may be a critical mechanism controlling the transition from adaptive hypertrophy to heart failure. Canopy 2 (CNPY2) was recently identified as a secreted, HIF-1α-regulated angiogenic growth factor. As angiogenic factors play important roles in the development of myocardial hypertrophy, we investigated the role of CNPY2 in molecular and functional changes during development of chronic heart failure using cardiac-specific transgenic (TG) mice that overexpress human CNPY2.

METHODS AND RESULTS

We generated TG mice that constitutively express CNPY2 in the myocardium. Cardiomyopathy was induced in TG and wild-type (WT) mice by transverse aortic constriction (TAC). WT mice developed significant ventricular hypertrophy at 4 weeks and severe dilatation and heart failure at 12 weeks after TAC. However, TG mice preserved much better cardiac structure and function, with less severe ventricular dilatation and markedly reduced cardiac apoptosis and fibrosis following TAC. Excess CNPY2 in TG mice prevented significant loss of vasculature up to 12 weeks after TAC injury, resulting in a better local myocardial environment that facilitated myocyte survival and prevented excessive matrix remodelling compared with WT mice. TG mice had less accumulation of endogenous tumor suppressor p53 after TAC, indicating intrinsic activation of the p53-mediated repression of HIF-1α, and Cnpy2 was diminished in TG mice compared with WT controls.

CONCLUSION

Our study showed a correlation between downregulation of endogenous mouse Cnpy2 and p53-mediated HIF-1α inhibition during late-stage hypertrophic development. Additional CNPY2 attenuated the transition from compensatory hypertrophic response to maladaptive ventricular dilatation and heart failure.

Influence of glutathione-S-transferase (GST) inhibition on lung epithelial cell injury: role of oxidative stress and metabolism

Oxidant-mediated tissue injury is key to the pathogenesis of acute lung injury. Glutathione- S-transferases (GSTs) are important detoxifying enzymes that catalyze the conjugation of glutathione with toxic oxidant compounds and are associated with acute and chronic inflammatory lung diseases. We hypothesized that attenuation of cellular GST enzymes would augment intracellular oxidative and metabolic stress and induce lung cell injury. Treatment of murine lung epithelial cells with GST inhibitors, ethacrynic acid (EA), and caffeic acid compromised lung epithelial cell viability in a concentration-dependent manner. These inhibitors also potentiated cell injury induced by hydrogen peroxide (H2O2), tert-butyl-hydroperoxide, and hypoxia and reoxygenation (HR). SiRNA-mediated attenuation of GST-π but not GST-μ expression reduced cell viability and significantly enhanced stress (H2O2/HR)-induced injury. GST inhibitors also induced intracellular oxidative stress (measured by dihydrorhodamine 123 and dichlorofluorescein fluorescence), caused alterations in overall intracellular redox status (as evidenced by NAD+/NADH ratios), and increased protein carbonyl formation. Furthermore, the antioxidant N-acetylcysteine completely prevented EA-induced oxidative stress and cytotoxicity. Whereas EA had no effect on mitochondrial energetics, it significantly altered cellular metabolic profile. To explore the physiological impact of these cellular events, we used an ex vivo mouse-isolated perfused lung model. Supplementation of perfusate with EA markedly affected lung mechanics and significantly increased lung permeability. The results of our combined genetic, pharmacological, and metabolic studies on multiple platforms suggest the importance of GST enzymes, specifically GST-π, in the cellular and whole lung response to acute oxidative and metabolic stress. These may have important clinical implications.

Shear stress and VEGF enhance endothelial differentiation of human adipose-derived stem cells

Herein we combine chemical and mechanical stimulation to investigate the effects of vascular endothelial growth factor (VEGF) and physiological shear stress in promoting the differentiation human adipose derived stem cells (ADSCs) into endothelial cells. ADSCs were isolated and characterized; endothelial differentiation was promoted by culturing confluent cells in 50 ng/ml VEGF under physiological shear stress for up to 14 days. Afterwards, endothelial cells were seeded onto collagen or acellular aortic valve matrices and exposed to four culture conditions: shear stress + VEGF; shear stress - VEGF; static + VEGF and static - VEGF. After 7 days, phenotype was investigated. ADSCs subjected to shear stress and VEGF express a comprehensive range of specific endothelial markers (vWF, eNOS and FLT-1 after 7 days and CD31, FLk-1 and VE-cadherin after 14 days) and maintain the phenotype when seeded onto scaffolds. Our protocol proved to be an efficient source of endothelial-like cells for tissue engineering based on autologous ADSC.

Biomarkers in mechanical circulatory support

Heart failure is a complex multifaceted syndrome occurring as a result of impaired cardiac function. Understanding the neurohormonal, inflammatory and molecular pathways involved in the pathophysiology of this syndrome has led to the development of effective and widely used pharmacological treatments. Despite this, mortality and hospitalization rates associated with this condition remain high. The natural course of this illness is usually progressive, often leading inexorably to end stage heart failure, for which orthotopic heart transplant is a treatment option but one with limited resource. In the past decade, mechanical circulatory support has emerged as a potential therapy for certain patients with advanced heart failure. This article reviews the published data regarding biomarkers in the setting of mechanical circulatory support, and highlights areas of ongoing work and potential future areas of interest.

Epicardial adipose tissue and atrial fibrillation

Atrial fibrillation (AF) is the most frequent cardiac arrhythmia in clinical practice. AF is often associated with profound functional and structural alterations of the atrial myocardium that compose its substrate. Recently, a relationship between the thickness of epicardial adipose tissue (EAT) and the incidence and severity of AF has been reported. Adipose tissue is a biologically active organ regulating the metabolism of neighbouring organs. It is also a major source of cytokines. In the heart, EAT is contiguous with the myocardium without fascia boundaries resulting in paracrine effects through the release of adipokines. Indeed, Activin A, which is produced in abundance by EAT during heart failure or diabetes, shows a marked fibrotic effect on the atrial myocardium. The infiltration of adipocytes into the atrial myocardium could also disorganize the depolarization wave front favouring micro re-entry circuits and local conduction block. Finally, EAT contains progenitor cells in abundance and therefore could be a source of myofibroblasts producing extracellular matrix. The study on the role played by adipose tissue in the pathogenesis of AF is just starting and is highly likely to uncover new biomarkers and therapeutic targets for AF.

Molecular changes after left ventricular assist device support for heart failure

Heart failure is associated with remodeling that consists of adverse cellular, structural, and functional changes in the myocardium. Until recently, this was thought to be unidirectional, progressive, and irreversible. However, irreversibility has been shown to be incorrect because complete or partial reversal can occur that can be marked after myocardial unloading with a left ventricular assist device (LVAD). Patients with chronic advanced heart failure can show near-normalization of nearly all structural abnormalities of the myocardium or reverse remodeling after LVAD support. However, reverse remodeling does not always equate with clinical recovery. The molecular changes occurring after LVAD support are reviewed, both those demonstrated with LVAD unloading alone in patients bridged to transplantation and those occurring in the myocardium of patients who have recovered enough myocardial function to have the device removed. Reverse remodeling may be attributable to a reversal of the pathological mechanisms that occur in remodeling or the generation of new pathways. A reduction in cell size occurs after LVAD unloading, which does not necessarily correlate with improved cardiac function. However, some of the changes in both the cardiac myocyte and the matrix after LVAD support are specific to myocardial recovery. In the myocyte, increases in the cytoskeletal proteins and improvements in the Ca²⁺ handling pathway seem to be specifically associated with myocardial recovery. Changes in the matrix are complex, but excessive scarring appears to limit the ability for recovery, and the degree of fibrosis in the myocardium at the time of implantation may predict the ability to recover.

Cardiac matrix: a clue for future therapy

Cardiac muscle is unique because it contracts ceaselessly throughout the life and is highly resistant to fatigue. The marvelous nature of the cardiac muscle is attributed to its matrix that maintains structural and functional integrity and provides ambient micro-environment required for mechanical, cellular and molecular activities in the heart. Cardiac matrix dictates the endothelium myocyte (EM) coupling and contractility of cardiomyocytes. The matrix metalloproteinases (MMPs) and their tissue inhibitor of metalloproteinases (TIMPs) regulate matrix degradation that determines cardiac fibrosis and myocardial performance. We have shown that MMP-9 regulates differential expression of micro RNAs (miRNAs), calcium cycling and contractility of cardiomyocytes. The differential expression of miRNAs is associated with angiogenesis, hypertrophy and fibrosis in the heart. MMP-9, which is involved in the degradation of cardiac matrix and induction of fibrosis, is also implicated in inhibition of survival and differentiation of cardiac stem cells (CSC). Cardiac matrix is distinct because it renders mechanical properties and provides a framework essential for differentiation of cardiac progenitor cells (CPC) into specific lineage. Cardiac matrix regulates myocyte contractility by EM coupling and calcium transients and also directs miRNAs required for precise regulation of continuous and synchronized beating of cardiomyocytes that is indispensible for survival. Alteration in the matrix homeostasis due to induction of MMPs, altered expression of specific miRNAs or impaired signaling for contractility of cardiomyocytes leads to catastrophic effects. This review describes the mechanisms by which cardiac matrix regulates myocardial performance and suggests future directions for the development of treatment strategies in cardiovascular diseases.

miR-17 targets tissue inhibitor of metalloproteinase 1 and 2 to modulate cardiac matrix remodeling

We aimed to investigate the role of miR-17 in cardiac matrix remodeling following myocardial infarction (MI). Using real-time PCR, we quantified endogenous miR-17 in infarcted mouse hearts. Compared with related microRNAs, miR-17 was up-regulated most dramatically: 3.7-fold and 2.4-fold in the infarct region 3 and 7 d post-MI, respectively, and 2.4-fold in the border zone at d 3 compared to sham control (P<0.01). Chimeric luciferase reporter constructs were cloned for miR-17 target validation. miR-17 targeted the 3'-UTR of TIMP2 and the protein coding region of TIMP1. The miR-17 mimic decreased TIMP2 (P<0.01) and TIMP1 (P<0.05) protein expression compared with the scrambled control. Inhibition of endogenous miR-17 by in vivo antagomir delivery enhanced TIMP2 (P<0.01) and TIMP1 (P<0.05) protein expression compared to the mismatch group, decreased MMP9 activity (P<0.05), reduced infarct size as early as 7 d post-MI (P<0.05), and improved cardiac function (fractional shortening and fractional area contraction, P<0.05) at d 21 and 28 post-MI. Transgenic mice overexpressing miR-17 in the heart confirmed the deleterious role of miR-17 in matrix modulation. Our study suggests that miR-17 participates in the regulation of cardiac matrix remodeling and provides a novel therapeutic approach using miR-17 inhibitors to prevent remodeling and heart failure after MI.

Analysis of IL-17 gene polymorphisms in Chinese patients with dilated cardiomyopathy

Cardiomyopathy is one of the major causes of sudden death and/or progressive heart failure. Dilated cardiomyopathy (DCM), comprising 60% of the cases of identified cardiomyopathy, is the most common form of heart muscle disease. Interleukin 17 (IL-17) is a proinflammatory cytokine that has been implicated in the pathogenesis of various diseases. To evaluate the influence of IL-17A and IL-17F gene polymorphisms on the risk of DCM, a case-control study was conducted in a Chinese Han population. The TaqMan® SNP Genotyping Assay was used to genotype the SNP rs2275913 of IL-17A and SNP rs763780 of IL-17F in 288 DCM patients and 421 ethnicity-matched controls. No significant difference in genotypic and allelic frequencies between DCM patients and control subjects was observed. However, Results of stratified analysis revealed that rs763780 was associated with male DCM patients in a dominant genetic model (p=0.031, OR=1.83, 95% CI=1.04-3.22). Our results suggest that the tested two IL-17 SNPs, rs2275913 and rs763780, are not found to be associated with DCM in the Chinese population studied.

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.

Systems-based biological concordance and predictive reproducibility of gene set discovery methods in cardiovascular disease

The discovery of novel disease biomarkers is a crucial challenge for translational bioinformatics. Demonstration of both their classification power and reproducibility across independent datasets are essential requirements to assess their potential clinical relevance. Small datasets and multiplicity of putative biomarker sets may explain lack of predictive reproducibility. Studies based on pathway-driven discovery approaches have suggested that, despite such discrepancies, the resulting putative biomarkers tend to be implicated in common biological processes. Investigations of this problem have been mainly focused on datasets derived from cancer research. We investigated the predictive and functional concordance of five methods for discovering putative biomarkers in four independently-generated datasets from the cardiovascular disease domain. A diversity of biosignatures was identified by the different methods. However, we found strong biological process concordance between them, especially in the case of methods based on gene set analysis. With a few exceptions, we observed lack of classification reproducibility using independent datasets. Partial overlaps between our putative sets of biomarkers and the primary studies exist. Despite the observed limitations, pathway-driven or gene set analysis can predict potentially novel biomarkers and can jointly point to biomedically-relevant underlying molecular mechanisms.

Polymorphisms of matrix metalloproteinases in systolic heart failure: role on disease susceptibility, phenotypic characteristics, and prognosis

BACKGROUND

The role of matrix metalloproteinases (MMPs) polymorphisms on heart failure (HF) susceptibility, phenotypic characteristics, and prognosis has been poorly explored.

METHODS AND RESULTS

We studied 313 HF patients with left ventricular systolic dysfunction and 367 healthy control subjects. Genotyping of MMP-1 (-1607 1G/2G), MMP-3 (-1171 5A/6A), and MMP-9 (-1562 C/T) polymorphisms was performed by polymerase chain reaction. Allelic and genotypic frequencies of MMP-1, -3, and -9 were similar in HF patients and controls. MMP1 2G allele carriers were positively associated to ischemic etiology and history of myocardial infarction (all P values <.05). Patients were followed-up for a median of 40 months and 58 HF-related deaths occurred during this period. HF-related survival was significantly better in MMP1 2G allele carriers (71% versus 42% for 1G/1G patients, P = .002) and in MMP-3 6A allele carriers (70% versus 61% for 5A/5A patients, P = .064), particularly in non-ischemic patients (P = .039). MMP1 2G allele was independently associated to HF survival after adjustment for several other predictors of risk (hazard ratio 0.47, 95% confidence interval 0.27 to 0.82; P = .008).

CONCLUSIONS

MMP-1, -3, and -9 polymorphisms were not associated to HF susceptibility. However, MMP1 2G allele carriers were related to a higher prevalence of ischemic etiology among patients with systolic HF and better HF-related prognosis.

Zinc supplementation results in improved therapeutic potential of bone marrow-derived mesenchymal stromal cells in a mouse ischemic limb model

BACKGROUND AIMS

We wanted to determine whether zinc supplementation can inhibit bone marrow-derived mesenchymal stromal cell (MSC) apoptosis and enhance their tissue regenerative potential a in mouse ischemic hindlimb model.

METHODS

Rat bone marrow cells were cultured and the resulting MSC were passaged for 3-7 generations. The proliferation and apoptosis of MSC was examined by 3-[4,5-dimethyl-2-thiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay and flow cytometry analysis. The activation of protein kinases B (Akt) was determined by Western blots. Vascular endothelial growth factor (VEGF) levels were examined by enzyme-linked immunosorbent assay. The mouse hindlimb ischemic model was established by ligating the right femoral artery. Mice received MSC, zinc-treated MSC or vehicle. The blood flow was assessed by laser Doppler imaging. The survival rate of donor cells was quantified by real-time polymerase chain reaction for the sex-determining region of the Y-chromosome (Sry). Angiogenesis was assessed by histochemical staining and immunofluoresence staining.

RESULTS

Supplementation with physiologic amounts of zinc caused a marked attenuation of cell apoptosis, enhanced cell viabilities, increased VEGF release and up-regulated Akt activation. Zinc-treated MSC delivered into ischemic hindlimbs resulted in significant improvements in limb blood perfusion by increased implanted MSC survival and stimulated angiogenesis.

CONCLUSIONS

This study demonstrates the potential of zinc supplement to enhance survival of engrafted MSC and ameliorate their tissue regenerative potential in a mouse ischemic hindlimb model.

Temporal and spatial expression of matrix metalloproteinases and tissue inhibitors of metalloproteinases following myocardial infarction

Following a myocardial infarction (MI), the homeostatic balance between matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) is disrupted as part of the left ventricle (LV) response to injury. The full complement of responses to MI has been termed LV remodeling and includes changes in LV size, shape and function. The following events encompass the LV response to MI: (1) inflammation and LV wall thinning and dilation, (2) infarct expansion and necrotic myocyte resorption, (3) accumulation of fibroblasts and scar formation, and (4) endothelial cell activation and neovascularization. In this review, we will summarize MMP and TIMP roles during these events, focusing on the spatiotemporal localization and MMP and TIMP effects on cellular and tissue-level responses. We will review MMP and TIMP structure and function, and discuss specific MMP roles during both the acute and chronic phases post-MI, which may provide insight into novel therapeutic targets to limit adverse remodeling in the MI setting.

The Treg/Th17 imbalance in patients with idiopathic dilated cardiomyopathy

To assess whether Treg/Th17 balance was broken in patients with idiopathic dilated cardiomyopathy (DCM). We studied 25 patients who were diagnosed as idiopathic DCM (18 men and seven women, mean age 35.6 +/- 5.2) and 25 normal persons (18 men and seven women, mean age 33.8 +/- 4.9). Then, we detected Treg/Th17 functions on different levels including cell frequencies, related cytokine secretion and key transcription factors in patients with idiopathic DCM and controls. The results demonstrated that patients with idiopathic DCM revealed significant increase in peripheral Th17 number, Th17-related cytokines (IL-17, IL-6, IL-23) and transcription factor (RORgammat) levels and obvious decrease in Treg number, Treg-related cytokines (TGF-beta1 and IL-10) and transcription factor (Foxp3) levels when compared to normal persons. Results indicated that Treg/Th17 functional imbalance existed in patients with idiopathic DCM, suggesting a potential role for Treg/Th17 imbalance in the development of idiopathic DCM.

Intramyocardial fibroblast myocyte communication

Cardiac fibroblasts are emerging as key components of normal cardiac function, as well as the response to stressors and injury. These most numerous cells of the heart interact with myocytes via paracrine mechanisms, alterations in extracellular matrix homeostasis, and direct cell-cell interactions. It is possible that they are a contributor to the inability of adult myocytes to proliferate and may influence cardiac progenitor biology. Furthering our understanding of how cardiac fibroblasts and myocytes interact may provide an avenue to novel treatments for heart failure prevention. This review discusses the most recent concepts in cardiac fibroblast-myocyte communication and areas of potential future research.

Age-dependent increases in interstitial collagenase and MAP Kinase levels are exacerbated by superoxide dismutase deficiencies

Many age-associated degenerative diseases commonly involve degradation of the extracellular matrix and aberrant matrix metalloproteinase-1 (MMP-1) expression. In diverse cell lines MMP-1 or interstitial collagenase (CL) expression is tightly regulated through a network of signals involving reactive oxygen species (ROS). However, whether the in vivo age-associated increase in CL expression is also sensitive to ROS-mediated signaling has not been established. To evaluate the contribution of ROS to the age-dependent increase in CL we monitored the levels of murine CL in two well-established models of oxidant stress. Analysis of murine CL levels in mice deficient in either of the intracellular superoxide dismutases (Sod2(+/-) or Sod1(-/-)) revealed its age- and redox-dependent expression relative to WT controls. Both age- and redox-dependent increases in murine CL expression were associated with elevations in phosphorylation of the MAP Kinases, Erk, JNK and p38. CL expression was highest in renal and skeletal muscle tissue from the aged Sod1(-/-) mice and was associated with a decrease in collagen staining. These findings suggest that MAPK signaling and CL production are both age- and redox-responsive. The redox sensitivity of age-associated CL expression suggests that degenerative disease associated with aberrant matrix remodeling and oxidant stress may be amenable to antioxidant-based therapies.

Overexpression of the transcription factor Hand1 causes predisposition towards arrhythmia in mice

Elevated levels of the cardiac transcription factor Hand1 have been reported in several adult cardiac diseases but it is unclear whether this change is itself maladaptive with respect to heart function. To test this possibility, we have developed a novel, inducible transgenic system, and used it to overexpress Hand1 in adult mouse hearts. Overexpression of Hand1 in the adult mouse heart leads to mild cardiac hypertrophy and a reduction in life expectancy. Treated mice show no significant fibrosis, myocyte disarray or congestive heart failure, but have a greatly reduced threshold for induced ventricular tachycardia, indicating a predisposition to cardiac arrhythmia. Within 48 h, they show a significant loss of connexin43 protein from cardiac intercalated discs, with increased intercalated disc beta-catenin expression at protein and RNA levels. These changes are sustained during prolonged Hand1 overexpression. We propose that cardiac overexpression of Hand1 offers a useful mouse model of arrhythmogenesis and elevated HAND1 may provide one of the molecular links between the failing heart and arrhythmia.

Circulating tissue inhibitor of matrix metalloproteinase-4 (TIMP-4) in systemic sclerosis patients with elevated pulmonary arterial pressure

Decreased levels of matrix metalloproteinases (MMPs) or excess levels of their tissue inhibitors (TIMPs) may contribute to dysregulation of extracellular matrix turnover in systemic sclerosis (SSc). In a cross-sectional study of 106 SSc patients, we measured serum levels of TIMP-4 which is preferentially expressed in cardiovascular structures and searched for correlations with simultaneously performed echocardiography measurements of pulmonary artery systolic pressure (PASP), myocardial performance, and pulmonary function tests. TIMP-4, but not MMP-9, levels were significantly raised in patients with SSc than controls. However, in the subgroup of patients with PASP measurements lower to 40 mmHg (n = 69), TIMP-4 levels were comparable to controls irrespective of the presence of diffuse or limited skin involvement, or lung fibrosis. Individual PASP measurements suggestive of pulmonary hypertension were associated with increased TIMP-4 serum levels (P = .03), independently of age, extent of skin sclerosis, or lung fibrosis, suggesting a cardiopulmonary vasculature-specific role of TIMP-4 activation in SSc.

Choice of cell-delivery route for skeletal myoblast transplantation for treating post-infarction chronic heart failure in rat

BACKGROUND

Intramyocardial injection of skeletal myoblasts (SMB) has been shown to be a promising strategy for treating post-infarction chronic heart failure. However, insufficient therapeutic benefit and occurrence of ventricular arrhythmias are concerns. We hypothesised that the use of a retrograde intracoronary route for SMB-delivery might favourably alter the behaviour of the grafted SMB, consequently modulating the therapeutic effects and arrhythmogenicity.

METHODS AND RESULTS

Three weeks after coronary artery ligation in female wild-type rats, 5x10(6) GFP-expressing SMB or PBS only (control) were injected via either the intramyocardial or retrograde intracoronary routes. Injection of SMB via either route similarly improved cardiac performance and physical activity, associated with reduced cardiomyocyte-hypertrophy and fibrosis. Grafted SMB via either route were only present in low numbers in the myocardium, analysed by real-time PCR for the Y-chromosome specific gene, Sry. Cardiomyogenic differentiation of grafted SMB was extremely rare. Continuous ECG monitoring by telemetry revealed that only intramyocardial injection of SMB produced spontaneous ventricular tachycardia up to 14 days, associated with local myocardial heterogeneity generated by clusters of injected SMB and accumulated inflammatory cells. A small number of ventricular premature contractions with latent ventricular tachycardia were detected in the late-phase of SMB injection regardless of the injection-route.

CONCLUSION

Retrograde intracoronary injection of SMB provided significant therapeutic benefits with attenuated early-phase arrhythmogenicity in treating ischaemic cardiomyopathy, indicating the promising utility of this route for SMB-delivery. Late-phase arrhythmogenicity remains a concern, regardless of the delivery route.

Left ventricular assist device-induced molecular changes in the failing myocardium

PURPOSE OF REVIEW

There is considerable increase in the use of left ventricular assist devices for the treatment of severe heart failure. Traditionally viewed as a bridge to transplantation and more recently as a destination therapy, left ventricular assist device support is now recognized to offer potential for myocardial recovery through reverse remodeling, a potential that is further enhanced by combination with pharmacologic therapy. In this study, we examine the molecular changes associated with left ventricular assist device support and how these may contribute to the recovery process.

RECENT FINDINGS

Studies in both patients and experimental models have demonstrated that improved function is associated with alterations in several key pathways including cell survival, cytokine signaling, calcium handling, adrenergic receptor signaling, cytoskeletal and contractile proteins, energy metabolism, extracellular matrix, and endothelial and microvascular functions. Moreover, the unique research opportunities offered by left ventricular assist device analysis are beginning to distinguish changes associated with recovery from those of mechanical unloading alone and identify potential predictors and novel therapeutic targets capable of enhancing myocardial repair.

SUMMARY

Significant progress has been made toward revealing molecular changes associated with myocardial recovery from heart failure. These studies also offer new insight into the pathogenesis of heart failure and point to novel therapeutic strategies.

Plasma biomarkers of myocardial fibrosis and remodeling in terminal heart failure patients supported by mechanical circulatory support devices

BACKGROUND

In this study we analyzed putative biomarkers for myocardial remodeling in plasma from 55 endstage heart failure patients with the need for mechanical circulatory support (MCS). We compared our data to 40 healthy controls and examined if MCS by either ventricular assist devices or total artificial hearts has an impact on plasma concentrations of remodeling biomarkers.

METHODS & RESULTS

Plasma biomarkers were analysed pre and 30 days post implantation of a MCS device using commercially available enzyme linked immunosorbent assays (ELISA). We observed that the plasma concentrations of remodeling biomarkers: tissue inhibitor of metalloproteinase 1 (TIMP1), tenascin C (TNC), galectin 3 (LGALS3), osteopontin (OPN) and of neurohumoral biomarker brain natriuretic peptide (BNP), are significantly elevated in patients with terminal heart failure compared to healthy controls. We did not find elevated plasma concentrations for matrix metalloproteinase 2 (MMP2) and procollagen I C-terminal peptide (PCIP). However, only BNP plasma levels were reduced by MCS, whereas the concentrations of remodeling biomarkers remained elevated or even increased further 30 days after MCS. LGALS3 plasma concentrations at device implantation were significantly higher in patients who did not survive MCS due to multi organ failure (MOF).

CONCLUSIONS

Our findings indicate that mechanical unloading in endstage heart failure is not reflected by a rapid reduction of remodeling plasma biomarkers.

Cardiac remodeling in obesity

The dramatic increase in the prevalence of obesity and its strong association with cardiovascular disease have resulted in unprecedented interest in understanding the effects of obesity on the cardiovascular system. A consistent, but puzzling clinical observation is that obesity confers an increased susceptibility to the development of cardiac disease, while at the same time affording protection against subsequent mortality (termed the obesity paradox). In this review we focus on evidence available from human and animal model studies and summarize the ways in which obesity can influence structure and function of the heart. We also review current hypotheses regarding mechanisms linking obesity and various aspects of cardiac remodeling. There is currently great interest in the role of adipokines, factors secreted from adipose tissue, and their role in the numerous cardiovascular complications of obesity. Here we focus on the role of leptin and the emerging promise of adiponectin as a cardioprotective agent. The challenge of understanding the association between obesity and heart failure is complicated by the multifaceted interplay between various hemodynamic, metabolic, and other physiological factors that ultimately impact the myocardium. Furthermore, the end result of obesity-associated changes in the myocardial structure and function may vary at distinct stages in the progression of remodeling, may depend on the individual pathophysiology of heart failure, and may even remain undetected for decades before clinical manifestation. Here we summarize our current knowledge of this complex yet intriguing topic.

Role and possible mechanisms of clenbuterol in enhancing reverse remodelling during mechanical unloading in murine heart failure

Aims

Combined left ventricular assist device (LVAD) and pharmacological therapy has been proposed to favour myocardial recovery in patients with end-stage heart failure (HF). Clenbuterol (Clen), a β₂-adrenoceptor (β₂-AR) agonist, has been used as a part of this strategy. In this study, we investigated the direct effects of clenbuterol on unloaded myocardium in HF.

Methods and results

Left coronary artery ligation or sham operation was performed in male Lewis rats. After 4–6 weeks, heterotopic abdominal transplantation of the failing hearts into normal recipients was performed to induce LV unloading (UN). Recipient rats were treated with saline (Sal) or clenbuterol (2 mg/kg/day) via osmotic minipumps (HF + UN + Sal or HF + UN + Clen) for 7 days. Non-transplanted HF animals were treated with Sal (Sham + Sal, HF + Sal) or clenbuterol (HF + Clen). LV myocytes were isolated and studied using optical, fluorescence, and electrophysiological techniques. Clenbuterol treatment improved in vivo LV function measured with echocardiography (LVEF (%): HF 35.9 ± 2 [16], HF + Clen 52.1 ± 1.4 [16]; P < 0.001; mean ± SEM [n]). In combination with unloading, clenbuterol increased sarcomere shortening (amplitude (µm): HF + UN + Clen 0.1 ± 0.01 [50], HF + UN + Sal 0.07 ± 0.01 [38]; P < 0.001) by normalizing the depressed myofilament sensitivity to Ca²⁺ (slope of the linear relationship between Ca²⁺ transient and sarcomere shortening hysteresis loop during relaxation (μm/ratio unit): HF + UN + Clen 2.13 ± 0.2 [52], HF + UN + Sal 1.42 ± 0.13 [38]; P < 0.05).

Conclusion

Clenbuterol treatment of failing rat hearts, alone or in combination with mechanical unloading, improves LV function at the whole-heart and cellular levels by affecting cell morphology, excitation–contraction coupling, and myofilament sensitivity to calcium. This study supports the use of this drug in the strategy to enhance recovery in HF patients treated with LVADs and also begins to elucidate some of the possible cellular mechanisms responsible for the improvement in LV function.

IL-17 stimulates MMP-1 expression in primary human cardiac fibroblasts via p38 MAPK- and ERK1/2-dependent C/EBP-beta , NF-kappaB, and AP-1 activation

Matrix metalloproteinases (MMPs) degrade collagen and mediate tissue remodeling. The novel cytokine IL-17 is expressed during various inflammatory conditions and modulates MMP expression. We investigated the effect of IL-17 on MMP-1 expression in primary human cardiac fibroblasts (HCF) and delineated the signaling pathways involved. HCF were treated with recombinant human IL-17. MMP-1 expression was analyzed by Northern blotting, RT-quantitative PCR, Western blotting, and ELISA; transcriptional induction and transcription factor binding by EMSA, ELISA, and reporter assay; and p38 MAPK and ERK1/2 activation by protein kinase assays and Western blotting. Signal transduction pathways were investigated using pharmacological inhibitors, small interfering RNA (siRNA), and adenoviral dominant-negative expression vectors. IL-17 stimulated MMP-1 gene transcription, net mRNA levels, protein, and promoter-reporter activity in HCF. This response was blocked by IL-17 receptor-Fc chimera and IL-17 receptor antibodies, but not by IL-6, TNF-alpha, or IL-1beta antibodies. IL-17-stimulated type I collagenase activity was inhibited by the MMP inhibitor GM-6001 and by siRNA-mediated MMP-1 knockdown. IL-17 stimulated activator protein-1 [AP-1 (c-Fos, c-Jun, and Fra-1)], NF-kappaB (p50 and p65), and CCAAT enhancer-binding protein (C/EBP)-beta DNA binding and reporter gene activities, effects attenuated by antisense oligonucleotides, siRNA-mediated knockdown, or expression of dominant-negative signaling proteins. Inhibition of AP-1, NF-kappaB, or C/EBP activation attenuated IL-17-stimulated MMP-1 expression. IL-17 induced p38 MAPK and ERK1/2 activation, and inhibition by SB-203580 and PD-98059 blunted IL-17-mediated transcription factor activation and MMP-1 expression. Our data indicate that IL-17 induces MMP-1 in human cardiac fibroblasts directly via p38 MAPK- and ERK-dependent AP-1, NF-kappaB, and C/EBP-beta activation and suggest that IL-17 may play a critical role in myocardial remodeling.