Myocardial Gene Research Articles

Sex-based differences in myocardial gene expression in recently deceased organ donors with no prior cardiovascular disease.

Sex differences in the development of the normal heart and the prevalence of cardiomyopathies have been reported. The molecular basis of these differences remains unclear. Sex differences in the human heart might be related to patterns of gene expression. Recent studies have shown that sex specific differences in gene expression in tissues including the brain, kidney, skeletal muscle, and liver. Similar data is limited for the heart. Herein we address this issue by analyzing donor and post-mortem adult human heart samples originating from 46 control individuals to study whole-genome gene expression in the human left ventricle. Using data from the genotype tissue expression (GTEx) project, we compared the transcriptome expression profiles of male and female hearts. We found that genes located on sex chromosomes were the most abundant ones among the sexually dimorphic genes. The majority of differentially expressed autosomal genes were those involved in the regulation of inflammation, which has been found to be an important contributor to left ventricular remodeling. Specifically, genes on autosomal chromosomes encoding chemokines with inflammatory functions (e.g. CCL4, CX3CL1, TNFAIP3) and a gene that regulates adhesion of immune cells to the endothelium (e.g., VCAM1) were identified with sex-specific expression levels. This study underlines the relevance of sex as an important modifier of cardiac gene expression. These results have important implications in the understanding of the differences in the physiology of the male and female heart transcriptome and how they may lead to different sex specific difference in human cardiac health and its control.

Effect of Disclosing Genetic Risk for Coronary Heart Disease on Information Seeking and Sharing: The MI-GENES Study (Myocardial Infarction Genes).

Whether disclosing genetic risk for coronary heart disease (CHD) to individuals influences information seeking and information sharing is not known. We hypothesized that disclosing genetic risk for CHD to individuals influences information seeking and sharing. The MI-GENES study (Myocardial Infarction Genes) randomized participants (n=203) aged 45 to 65 years who were at intermediate CHD risk based on conventional risk factors and not on statins to receive their conventional risk score alone or also a genetic risk score based on 28 variants. CHD risk was disclosed by a genetic counselor and then discussed with a physician. Surveys assessing information seeking were completed before and after risk disclosure. Information sharing was assessed post-disclosure. Six-month post-disclosure, genetic risk score participants were more likely than conventional risk score participants to visit a website to learn about CHD (odds ratio [OR], 4.88 [confidence interval (CI), 1.55-19.13]; P=0.01), use the internet for information about how genetic factors affect CHD risk (OR, 2.11 [CI, 1.03-4.47]; P=0.04), access their CHD risk via a patient portal (OR, 2.99 [CI, 1.35-7.04]; P=0.01), and discuss their CHD risk with others (OR, 3.13 [CI, 1.41-7.47]; P=0.01), particularly their siblings (OR, 1.92 [CI, 1.06-3.51]; P=0.03), extended family (OR, 3.8 [CI, 1.37-12.38]; P=0.01), coworkers (OR, 2.42 [CI, 1.09-5.76]; P=0.03), and primary care provider (PCP; OR, 2.00 [CI, 1.08-3.75]; P=0.03). Disclosure of a genetic risk score for CHD increased information seeking and sharing. URL: https://clinicaltrials.gov/. Unique identifier: NCT01936675.

Abstract 395: A Synonymous Coding SNP Alters SCN5A Regulation by miR-24 and Associates With Non-Arrhythmic Death in Heart Failure

Mutations disrupting SCN5A coding sequence cause inherited arrhythmias and cardiomyopathy, and SNPs linked to SCN5A splicing, localization and function associate with heart failure-related sudden cardiac death. However, the clinical relevance of SNPs that modulate SCN5A expression levels remains understudied. Recently, we generated a transcriptome-wide map of microRNA (miR) binding sites in human heart and evaluated their interface with polymorphisms. Among >500 common SNPs residing within miR target regions, we identified a synonymous SNP (rs1805126) adjacent to a miR-24 site within SCN5A coding sequence. This SNP is known to reproducibly associate with heart rhythm measurements, but is not considered to be “causal”. Here, we show that miR-24 potently suppresses SCN5A and that rs1805126 modulates this regulation. In further exploring the clinical significance of this, we found that rs1805126 minor allele homozygosity associates with decreased cardiac SCN5A expression and increased mortality in heart failure patients. Unexpectedly, this risk was not linked with arrhythmic sudden cardiac death, but rather, with clinical signs of worsening heart failure (e.g. reduced ejection fraction) and myocardial gene expression changes related to bioenergetics, inflammation and extracellular remodeling. Together, these data attribute a molecular mechanism to this firmly-established GWAS SNP and highlight a novel and surprising link between common variations in SCN5A expression and non-arrhythmic death in heart failure.

Erratum to: Changes of myocardial gene expression and protein composition in patients with dilated cardiomyopathy after immunoadsorption with subsequent immunoglobulin substitution.

Unfortunately, the original version of this article contains an error. Table 1 contains the wrong information on the number of males in the non-responder group. All parameter values calculated for the non-responder group were correct and based on 13 non-responders. Additionally, the abbreviation of the statistical test for NYHA subclasses in responders and non-responders was changed to “f” (Fisher’s exact test, two-tailed) to display the test applied correctly. The corrected table is given below and the correct number of male subjects is given in bold. (Table Presented.).

Myeloid-related protein-14 regulates deep vein thrombosis.

Using transcriptional profiling of platelets from patients presenting with acute myocardial infarction, we identified myeloid-related protein-14 (MRP-14, also known as S100A9) as an acute myocardial infarction gene and reported that platelet MRP-14 binding to platelet CD36 regulates arterial thrombosis. However, whether MRP-14 plays a role in venous thrombosis is unknown. We subjected WT and Mrp-14-deficient (Mrp-14-/-) mice to experimental models of deep vein thrombosis (DVT) by stasis ligation or partial flow restriction (stenosis) of the inferior vena cava. Thrombus weight in response to stasis ligation or stenosis was reduced significantly in Mrp-14-/- mice compared with WT mice. The adoptive transfer of WT neutrophils or platelets, or the infusion of recombinant MRP-8/14, into Mrp-14-/- mice rescued the venous thrombosis defect in Mrp-14-/- mice, indicating that neutrophil- and platelet-derived MRP-14 directly regulate venous thrombogenesis. Stimulation of neutrophils with MRP-14 induced neutrophil extracellular trap (NET) formation, and NETs were reduced in venous thrombi harvested from Mrp-14-/- mice and in Mrp-14-/- neutrophils stimulated with ionomycin. Given prior evidence that MRP-14 also regulates arterial thrombosis, but not hemostasis (i.e., reduced bleeding risk), MRP-14 appears to be a particularly attractive molecular target for treating thrombotic cardiovascular diseases, including myocardial infarction, stroke, and venous thromboembolism.

128 Genomic insights of ecg strain patten in aortic stenosis: t wave inversion and st-segment depression are underlined by different molecular pathways

BackgroundECG strain pattern is frequently presented in AS patients as a marker of LV hypertrophy and is emerging as one of the predictors for AVR. Our previous study had demonstrated...

Analysis of region specific gene expression patterns in the heart and systemic responses after experimental myocardial ischemia.

AimsIschemic myocardial injury leads to the activation of inflammatory mechanisms and results in ventricular remodeling. Although great efforts have been made to unravel the molecular and cellular processes taking place in the ischemic myocardium, little is known about the effects on the surrounding tissue and other organs. The aim of this study was to determine region specific differences in the myocardium and in distant organs after experimental myocardial infarction by using a bioinformatics approach.Methods and ResultsA porcine closed chest reperfused acute myocardial infarction model and mRNA microarrays have been used to evaluate gene expression changes. Myocardial infarction changed the expression of 8903 genes in myocardial-, 856 in hepatic- and 338 in splenic tissue. Identification of myocardial region specific differences as well as expression profiling of distant organs revealed clear gene-regulation patterns within the first 24 hours after ischemia. Transcription factor binding site analysis suggested a strong role for Kruppel like factor 4 (Klf4) in the regulation of gene expression following myocardial infarction, and was therefore investigated further by immunohistochemistry. Strong nuclear Klf4 expression with clear region specific differences was detectable in porcine and human heart samples after myocardial infarction.ConclusionApart from presenting a post myocardial infarction gene expression database and specific response pathways, the key message of this work is that myocardial ischemia does not end at the injured myocardium. The present results have enlarged the spectrum of organs affected, and suggest that a variety of organ systems are involved in the co-ordination of the organism´s response to myocardial infarction.

Female rats with severe left ventricle volume overload exhibit more cardiac hypertrophy but fewer myocardial transcriptional changes than males

Aortic valve regurgitation (AR) imposes a volume overload (VO) to the left ventricle (LV). Male rats with a pathological heart overload usually progress more quickly towards heart failure than females. We examined whether a sexual dimorphism exists in the myocardial transcriptional adaptations to AR. Adult Wistar male and female rats either underwent a sham operation or were induced with AR and then followed for 26 weeks. Female AR rats gained relatively more LV mass than males (75 vs. 42%). They had a similar increase in LV chamber dimensions compared to males but more wall thickening. On the other hand, fatty acid oxidation (FAO)-related LV enzyme activity was only decreased in AR males. The expression of genes encoding FAO-related enzymes was only reduced in AR males and not in females. A similar situation was observed for the expression of genes involved in mitochondrial biogenesis or function as well as for genes encoding for transcription factors implicated in the control of bioenergetics and mitochondrial function (Errα, Errγ or Pgc1α). Although females develop more LV hypertrophy from severe VO, their myocardial gene expression remains closer to normal. This could provide survival benefits for females with severe VO.

Motivation, Perception, and Treatment Beliefs in the Myocardial Infarction Genes (MI‐GENES) Randomized Clinical Trial

Little is known about individuals' motivation, perception, and treatment beliefs towards the use of genetic information in risk estimates for coronary heart disease (CHD). In this study, participants at intermediate 10-year risk of CHD were randomized to receive either their estimated conventional risk score (CRS) alone, or a CRS and a genetic risk score (GRS), by a genetic counselor. Surveys on motivation to participate in and perception of genetic testing for CHD were administered at 3months and treatment beliefs at 6months following risk disclosure. Survey responses used Likert scales. Linear and logistic regression were used for analysis. Overall, motivation to participate in genomic clinical trials was favorable and did not differ between the CRS and GRS groups (16.95±0.82 vs. 17.58±0.83, p=0.091), but participants who initially received their GRS indicated a greater desire to find ways to improve health as a reason for participation (OR: 0.53 (95%CI: 0.29, 0.94), p=0.028). Perception of genetic testing was also favorable in both groups (15.29±0.39 vs. 15.12±0.40, p=0.835). Participants who initially received their GRS were more inclined to recommend genetic testing to family and friends (9.95±1.88 vs. 10.52±2.17, p=0.023). In the MI-GENES study, motivation to participate in and perception of genetic testing among study participants were overall favorable. Genetic risk disclosure was associated with increased motivation to recommend genetic testing to family and friends.

10 Macrophage-derived wnts are required for scar-free regeneration of the neonatal mouse myocardium

Objective In contrast to the adult, neonatal mice regenerate their myocardium following injury, at least during the first week after birth. 1 Macrophages (Mx) contribute to vessel formation and scar removal following neonatal myocardial infarction (MI) 2 . In the kidney 3 liver 4,7 and gut 5 Mx-derived WNTs are required for scar free regeneration following injury. Secretion of WNTs is dependent on acylation by Porcupine (PORCN). In the present study it was hypothesised that neonatal cardiac regeneration would be impaired in mice with Csf1r-Cre driven Mx specific Porcn deletion. 5 Methods Csf1r-EGFP(MacGreen), Porcn fl/ Csf1r Cre-ve and Porcn fl /Csf1r Cre+ve mice underwent coronary artery ligation at post-natal day 1 (P1). Functional loss 1 day after MI, and recovery by P21 were assessed by high-resolution ultrasound. Heart sections were stained with isolectin B4 (vessel density) and picrosirius res (fibrosis). Myocardial gene expression was determined by PCR array in wild-type (WT) mice after injury. Results At day 1 and day 7 post-MI, Csf1r-expressing cells accumulated within the injured myocardium, consistent with a role in regeneration. 2 At day 1 post-MI, fractional area change (FAC) decreased from 40.9% ± 1.6 to 18.0% ± 2.4% (p Porcn fl/ Csf1r Cre-ve and Porcnfl/Csf1rCre-ve mice respectively. By 21 days after MI, FAC had recovered to 47.4% ± 2.5% (p Porcn fl/ Csf1r Cre-ve and 45.8% ± 1.9% (p Porcn fl/ Csf1r Cre-ve littermates. Coronary vascularisation was restored in the infarct area by 21 days in both lines, but interstitial fibrosis was significantly higher in Porcn fl/ Csf1r Cre-ve (6.0 ± 0.9% LV) compared to Porcn fl/ Csf1r Cre-ve (3.8 ± 0.5% LV, p Wnt5b and Fzd2 , genes associated with regulation of fibrosis. 8 Conclusion Mx-derived WNTs are not required for re-vascularisation or restoration of myocardial function after neonatal myocardial injury, but are necessary for scar removal during regeneration. References Porrello et al . PNAS 2013; 110 :p187–92. Aurora et al . JCI 2014; 124 :p1382–92. Lin et al . PNAS 2010; 107 :p4194–99. Boulter et al . Nat Med 2012; 18 :572–9. Saha et al . Nat Com 2016; 7 :1–16. Derlindati et al . PLoS ONE 2015; 10 :1–17. Irvine et al . Fibrogenesis Tissue Repair 2015; 8 :19–32. Laeremans et al . Cardiovascular Research 2010; 87 :514–523.

Therapeutic Hypothermia Reduces the Inflammatory Response Following Ischemia/Reperfusion Injury in Rat Hearts.

Therapeutic hypothermia (TH) is known to protect against ischemia/reperfusion (I/R) injury. One mechanism of I/R injury includes secondary injury due to the inflammatory cascade. We hypothesized that TH reduces the inflammatory response following I/R injury. Rats were randomized to sham, normothermic, or hypothermic groups and subjected to 1 hour of coronary artery occlusion and 48 hours of reperfusion. Hypothermia was initiated, using the ThermoSuit® device, 2 minutes after the onset of coronary artery occlusion to a core temperature of 32°C, and then the rats were allowed to rewarm. After 48 hours, rats in the hypothermia group demonstrated a preserved left ventricular fractional shortening by echocardiography. TH decreased the inflammatory cytokines in the risk zone of the heart, which included monocyte chemoattractant protein-1, interleukin-6, tumor necrosis factor-α, and inducible nitric oxide synthase gene expression, and altered expression of the remodeling genes of matrix metalloproteinase and tissue inhibitor of metalloproteinase. Furthermore, rat inflammatory cytokines & receptors PCR array was performed and the data showed that 71 out of 84 genes were upregulated in the risk zone of normothermia hearts versus shams. The upregulation was largely reversed in the risk zone of hypothermia hearts compared to normothermia. TH preserves cardiac function, decreases excessive inflammatory gene expression, and regulates myocardial matrix remodeling related genes.

Chronically elevated bilirubin protects from cardiac reperfusion injury in the male Gunn rat.

Bilirubin is associated with reduced risk of cardiovascular disease, as evidenced in conditions of mild hyperbilirubinaemia (Gilbert's Syndrome). Little is known regarding myocardial stress resistance in hyperbilirubinaemic conditions or whether life-long exposure modifies cardiac function, which might contribute to protection from cardiovascular disease. Hyperbilirubinaemic rats and littermate controls underwent echocardiography at 3, 6 and 12 months of age, with hearts subsequently assessed for resistance to 30 min of ischaemia. Heart tissue was then collected for assessment of bilirubin content. No difference in baseline cardiac function was evident until 6 months onwards, where Gunn rats demonstrated aortic dilatation and reduced peak ejection velocities. Additionally, duration of ventricular ejection increased progressively, indicating a negative inotropic effect of bilirubin in vivo. Ex vivo analysis of baseline function revealed reduced left ventricular pressure development (LVDP) and contractility in hyperbilirubinaemic rats. Furthermore, stress resistance was improved in Gunn hearts: post-ischaemic recoveries of LVDP (76 ± 22% vs. 29 ± 17% Control, P < 0.01) and coronary flow (96 ± 9% vs. 86 ± 16% Control, P < 0.01) were improved in Gunn hearts, accompanied by reduced infarct area (21 ± 5% vs. 47 ± 15% Control, P < 0.01), and ventricular malondialdehyde and protein carbonyl content. Expression of myocardial nitric oxide-regulating genes including Nos1 and Noa1 were not significantly different. These data reveal life-long hyperbilirubinaemia induces age-dependent hypocontractility in male Gunn rats, and improved stress resistance. In addition, bilirubin exerts sex-independent effects on vascular structure, myocardial function and ischaemic tolerance, the latter likely mediated via bilirubin's antioxidant properties.

Pressure overload leads to an increased accumulation and activity of mast cells in the right ventricle.

Right ventricular (RV) remodeling represents a complex set of functional and structural adaptations in response to chronic pressure or volume overload due to various inborn defects or acquired diseases and is an important determinant of patient outcome. However, the underlying molecular mechanisms remain elusive. We investigated the time course of structural and functional changes in the RV in the murine model of pressure overload‐induced RV hypertrophy in C57Bl/6J mice. Using magnetic resonance imaging, we assessed the changes of RV structure and function at different time points for a period of 21 days. Pressure overload led to significant dilatation, cellular and chamber hypertrophy, myocardial fibrosis, and functional impairment of the RV. Progressive remodeling of the RV after pulmonary artery banding (PAB) in mice was associated with upregulation of myocardial gene markers of hypertrophy and fibrosis. Furthermore, remodeling of the RV was associated with accumulation and activation of mast cells in the RV tissue of PAB mice. Our data suggest possible involvement of mast cells in the RV remodeling process in response to pressure overload. Mast cells may thus represent an interesting target for the development of new therapeutic approaches directed specifically at the RV.

Increased Plasma ACE2 Activity is a Marker of Subclinical LV Systolic Dysfunction in Patients With Aortic Stenosis

Background: Subclinical left ventricular systolic dysfunction (LVSD) determined by global longitudinal strain (GLS) portends a poor prognosis in patients with aortic stenosis (AS). Angiotensin converting enzyme 2 (ACE2) is a membrane bound protein highly expressed in the human heart and functions to degrade the vasoconstrictor, profibrotic peptide, angiotensin II. Plasma ACE2 levels are elevated in patients with heart failure. In patients with AS, it is not known if early maladaptive processes within the myocardium are associated with changes in plasma and/or tissue ACE2. Aim/Methods: To investigate if subclinical LVSD in patients with AS is associated with elevated plasma ACE2 activity and/or reduced myocardial ACE2 gene expression. Plasma ACE2 activity was measured in 111 patients with AS and normal LV ejection fraction with satisfactory (≤ -15%, n = 77) and abnormal (> -15%, n = 34) GLS. Gene expression of ACE2 was measured in atrial samples collected from a subset of patients during aortic valve replacement (n = 20). Results: Median [25th, 75th quartile] plasma ACE2 activity was significantly higher in patients with abnormal versus normal GLS (29.0 [18.5, 45.25] vs. 20.8 [12.8, 35.04] pmol/ml/min; p = 0.03). Myocardial ACE2 gene expression was significantly reduced (0.5-fold, p = 0.01) in those with abnormal GLS (n = 10) compared to normal GLS (n = 10). Plasma ACE2 activity correlated negatively with ACE2 mRNA (R = - 0.45, p = 0.047). Conclusions: In patients with AS, elevated plasma ACE2 activity is associated with subclinical LVSD and reduced myocardial ACE2 gene expression. Approaches to enhance cardiac ACE2 may have a role in preventing progression to overt LV dysfunction in AS.

Etanercept protects rat cardiomyocytes against hypertrophy by regulating inflammatory cytokines secretion and cell apoptosis.

We aimed to investigate the effect of etanercept, a tumor necrosis factor-α (TNF-α) inhibitor, on rat cardiomyocyte hypertrophy and its underlying mechanism. Primary neonatal rat cardiomyocytes were isolated from Sprague-Dawley rats. The model of rat cardiomyocyte hypertrophy was induced by endothelin, and then treated with different concentrations of etanercept (1, 10, and 50 μM). After treatment, cell counts, viability and cell apoptosis were evaluated. The mRNA levels of myocardial hypertrophy marker genes, including atrial natriuretic factor (ANF), matrix metalloproteinase (MMP)-9 and MMP-13, were detected by qRT-PCR, and the expressions of apoptosis-related proteins (Bcl-2 and Bax) were measured by western blotting. The protein levels of transforming growth factor-β1 (TGF-β1), interleukin (IL)-1β, IL-6, leukemia inhibitory factor (LIF) and cardiotrophin-1 (CT-1) were determined using enzyme linked immunosorbent assay (ELISA) kits. In the present study, TNF-α level in cardiomyocytes with hypertrophy was significantly enhanced (P<0.05). Compared to the model group, cell number and viability were significantly increased and ratio of apoptotic cells was reduced by etanercept (P<0.05, P<0.01, or P<0.001). In addition, etanercept remarkably reduced the mRNA levels of ANF, MMP-9 and MMP-13, inhibited the expression of Bax, and increased the expression of Bcl-2 compared to the model group (P<0.05). ELISA results further showed that etanercept lowered the levels of IL-1β, IL-6, LIF and CT-1 but not TGF-β1 compared to the model group (P<0.05). Etanercept may protect rat cardiomyocytes from hypertrophy by inhibiting inflammatory cytokines secretion and cell apoptosis.

Molecular Cardiac Surgery with Recirculating Delivery (MCARD): Procedure and Vector Transfer.

Despite progress in clinical treatment, cardiovascular diseases are still the leading cause of morbidity and mortality worldwide. Therefore, novel therapeutic approaches are needed, targeting the underlying molecular mechanisms of disease with improved outcomes for patients. Gene therapy is one of the most promising fields for the development of new treatments for the advanced stages of cardiovascular diseases. The establishment of clinically relevant methods of gene transfer remains one of the principal limitations on the effectiveness of gene therapy. Recently, there have been significant advances in direct and transvascular gene delivery methods. The ideal gene transfer method should be explored in clinically relevant large animal models of heart disease to evaluate the roles of specific molecular pathways in disease pathogenesis. Characteristics of the optimal technique for gene delivery include low morbidity, an increased myocardial transcapillary gradient, esxtended vector residence time in the myocytes, and the exclusion of residual vector from the systemic circulation after delivery to minimize collateral expression and immune response. Here we describe myocardial gene transfer techniques with molecular cardiac surgery with recirculating delivery in a large animal model of post ischemic heart failure.

Allele-specific expression in the human heart and its application to postoperative atrial fibrillation and myocardial ischemia.

BackgroundAllele-specific expression (ASE) is differential expression of each of the two chromosomal alleles of an autosomal gene. We assessed ASE patterns in the human left atrium (LA, n = 62) and paired samples from the left ventricle (LV, n = 76) before and after ischemia, and tested the utility of differential ASE to identify genes associated with postoperative atrial fibrillation (poAF) and myocardial ischemia.MethodsFollowing genotyping from whole blood and whole-genome sequencing of LA and LV samples, we called ASE using sequences overlapping heterozygous SNPs using rigorous quality control to minimize false ASE calling. ASE patterns were compared between cardiac chambers and with a validation cohort from cadaveric tissue. ASE patterns in the LA were compared between patients who had poAF and those who did not. Changes in ASE in the LV were compared between paired baseline and post-ischemia samples.ResultsASE was found for 3404 (5.1%) and 8642 (4.0%) of SNPs analyzed in the LA and LV, respectively. Out of 6157 SNPs with ASE analyzed in both chambers, 2078 had evidence of ASE in both LA and LV (p < 0.0001). The SNP with the greatest ASE difference in the LA of patients with and without postoperative atrial fibrillation was within the gelsolin (GSN) gene, previously associated with atrial fibrillation in mice. The genes with differential ASE in poAF were enriched for myocardial structure genes, indicating the importance of atrial remodeling in the pathophysiology of AF. The greatest change in ASE between paired post-ischemic and baseline samples of the LV was in the zinc finger and homeodomain protein 2 (ZHX2) gene, a modulator of plasma lipids. Genes with differential ASE in ischemia were enriched in the ubiquitin ligase complex pathway associated with the ischemia-reperfusion response.ConclusionsOur results establish a pattern of ASE in the human heart, with a high degree of shared ASE between cardiac chambers as well as chamber-specific ASE. Furthermore, ASE analysis can be used to identify novel genes associated with (poAF) and myocardial ischemia.Electronic supplementary materialThe online version of this article (doi:10.1186/s13073-016-0381-1) contains supplementary material, which is available to authorized users.

Targeted myocardial gene expression in failing hearts by RNA sequencing

BackgroundMyocardial recovery with left ventricular assist device (LVAD) therapy is highly variable and difficult to predict. Next generation ribonucleic acid (RNA) sequencing is an innovative, rapid, and quantitative approach to gene expression profiling in small amounts of tissue. Our primary goal was to identify baseline transcriptional profiles in non-ischemic cardiomyopathies that predict myocardial recovery in response to LVAD therapy. We also sought to verify transcriptional differences between failing and non-failing human hearts.MethodsRNA was isolated from failing (n = 16) and non-failing (n = 8) human hearts. RNA from each patient was reverse transcribed and quantitatively sequenced on the personal genome machine (PGM) sequencer (Ion torrent) for 95 heart failure candidate genes. Coverage analysis as well as mapping the reads and alignment was done using the Ion Torrent Browser Suite™. Differential expression analyses were conducted by empirical analysis of digital gene expression data in R (edgeR) to identify differential expressed genes between failing and non-failing groups, and between responder and non-responder groups respectively. Targeted cardiac gene messenger RNA (mRNA) expression was analyzed in proportion to the total number of reads. Gene expression profiles from the PGM sequencer were validated by performing RNA sequencing (RNAseq) with the Illumina Hiseq2500 sequencing system.ResultsThe failing sample population was 75% male with an average age of 50 and a left ventricular ejection fraction (LVEF) of 16%. Myosin light chain kinase (MYLK) and interleukin (IL)-6 genes expression were significantly higher in LVAD responders compared to non-responders. Thirty-six cardiac genes were expressed differentially between failing and non-failing hearts (23 decreased, 13 elevated). MYLK, Beta-1 adrenergic receptor (ADRB1) and myosin heavy chain (MYH)-6 expression were among those significantly decreased in failing hearts compared to non-failing hearts. Natriuretic peptide B (NPPB) and IL-6 were significantly elevated. Targeted gene expression profiles obtained from the Ion torrent PGM sequencer were consistent with those obtained from Illumina HiSeq2500 sequencing system.ConclusionsHeart failure is associated with a network of transcriptional changes involving contractile proteins, metabolism, adrenergic receptors, protein phosphorylation, and signaling factors. Myocardial MYLK and IL-6 expression are positively correlated with ejection fraction (EF) response to LVAD placement. Targeted RNA sequencing of myocardial gene expression can be utilized to predict responders to LVAD therapy and to better characterize transcriptional changes in human heart failure.

Trimetazidine attenuates pressure overload-induced early cardiac energy dysfunction via regulation of neuropeptide Y system in a rat model of abdominal aortic constriction.

BackgroundMetabolism remodeling has been recognized as an early event following cardiac pressure overload. However, its temporal association with ventricular hypertrophy has not been confirmed. Moreover, whether trimetazidine could favorably affect this process also needs to be determined. The aim of the study was to explore the temporal changes of myocardial metabolism remodeling following pressure-overload induced ventricular hypertrophy and the potential favorable effect of trimetazidine on myocardial metabolism remodeling.MethodsA rat model of abdominal aortic constriction (AAC)-induced cardiac pressure overload was induced. These rats were grouped as the AAC (no treatment) or TMZ group according to whether oral trimetazidine (TMZ, 40 mg/kg/d, for 5 days) was administered. Changes in cardiac structures were sequentially evaluated via echocardiography. The myocardial ADP/ATP ratio was determined to reflect the metabolic status, and changes in serum neuropeptide Y systems were evaluated.ResultsMyocardial metabolic disorder was acutely induced as evidenced by an increased ADP/ATP ratio within 7 days of AAC before the morphological changes in the myocardium, accompanied by up-regulation of serum oxidative stress markers and expression of fetal genes related to hypertrophy. Moreover, the serum NPY and myocardial NPY-1R, 2R, and 5R levels were increased within the acute phase of AAC-induced cardiac pressure overload. Pretreatment with TMZ could partly attenuate myocardial energy metabolic homeostasis, decrease serum levels of oxidative stress markers, attenuate the induction of hypertrophy-related myocardial fetal genes, inhibit the up-regulation of serum NPY levels, and further increase the myocardial expression of NPY receptors.ConclusionsCardiac metabolic remodeling is an early change in the myocardium before the presence of typical morphological ventricular remodeling following cardiac pressure overload, and pretreatment with TMZ may at least partly reverse the acute metabolic disturbance, perhaps via regulation of the NPY system.

Abstract 13220: Distinct Disease Mechanisms Drive Pediatric and Adult Dilated Cardiomyopathy

Background: Numerous clinical studies have suggested that adult heart failure (HF) therapies are less effective in children with dilated cardiomyopathy (DCM). The mechanistic basis for this phenomenon is poorly defined. Collectively, adult HF therapeutics target a process termed adverse remodeling, a common pathway by which the adult heart responds to injury. We hypothesized that pediatric and adult DCM comprise distinct pathological entities in that children do not undergo adverse remodeling. Methods: LV specimens were obtained from donor pediatric and adult controls (24), pediatric DCM (31) and adult DCM patients (33). Pathological evidence of adverse remodeling including myocardial fibrosis, cardiomyocyte hypertrophy, and gene expression was examined using immunostaining, electron microscopy and RNA sequencing. Results: Consistent with the established pathophysiology of adult HF, adults with DCM displayed marked increases in myocardial fibrosis compared to donor controls (both p&lt;0.01)(Figure). In contrast, pediatric DCM had minimal evidence of fibrosis compared to both aged-matched controls and adults with DCM. Examination of cardiomyocyte hypertrophy and capillary density demonstrated less extensive cardiomyocyte hypertrophy and capillary rarefaction in pediatric compared to adult DCM patients. Electron microscopy revealed similar sarcomere thickness and length between control and pediatric DCM specimens. RNA sequencing demonstrated that genes associated with adverse remodeling were not up-regulated in pediatric DCM specimens. Conclusions: These findings demonstrate that children with DCM display minimal evidence of adverse remodeling; suggesting pediatric and adult DCM may represent different pathological entities. Collectively, these data provide a mechanistic basis to understand why adult HF therapeutics may not work in children, and suggest the possibility that distinct therapies may be needed for pediatric DCM.