Hypertrophic Heart Disease Research Articles

Deficiency of the Immunoproteasome LMP10 Subunit Attenuates Angiotensin II-Induced Cardiac Hypertrophic Remodeling via Autophagic Degradation of gp130 and IGF1R.

Background/AimHypertensive cardiac hypertrophy is the leading cause of cardiac remodeling and heart failure. We recently demonstrated that the immunoproteasome, an inducible form of the constitutive proteasome, plays a critical role in regulating cardiovascular diseases. However, the role of the immunoproteasome LMP10 (β2i) catalytic subunit in the regulation of angiotensin II (Ang II)-induced cardiac hypertrophic remodeling remains unclear.MethodsWild-type (WT) and LMP10 knockout (KO) mice were infused with Ang II 1,000 ng/kg/min for 2 weeks. Blood pressure was measured using a tail-cuff system. Cardiac function and hypertrophic remodeling were examined by echocardiography and histological staining. The expression levels of genes and proteins were examined with quantitative real-time PCR and immunoblotting analysis, respectively.ResultsLMP10 mRNA and protein expression was significantly increased in Ang II-stimulated hearts and primary cardiomyocytes. Moreover, Ang II infusion for 2 weeks increased systolic blood pressure, abnormal cardiac function, hypertrophy, fibrosis, and inflammation in WT mice, which were significantly reversed in KO mice. Moreover, a marked reduction in the protein levels of insulin growth factor-1 receptor (IGF1R), glycoprotein 130 (gp130), and phosphorylated AKT, mTOR, STAT3, and ERK1/2 and an increase in the LC3II/I ratio were also observed in LMP10 KO mice compared with WT mice after Ang II infusion. In vitro culture experiments confirmed that LMP10 knockdown activated autophagy and increased IGF1R and gp130 degradation, leading to the inhibition of cardiomyocyte hypertrophy. However, inhibiting autophagy with chloroquine reversed this effect.ConclusionThe results of this study indicate that LMP10 KO attenuates Ang II-induced cardiac hypertrophic remodeling via the autophagy-dependent degradation of IGF1R and gp130, and suggests that LMP10 may be a novel therapeutic target for hypertrophic heart diseases.

ZDHHC9‐mediated palmitoylation promotes hypertrophic signaling in the heart

Heart disease remains a leading cause of mortality in the United States, contributing to over 600,000 deaths per year in the United States. Notwithstanding, the molecular mechanisms underlying the pathophysiology of heart disease remain largely elusive. Receptors, ion channels, and signaling proteins that regulate cardiac contractility and physiology are modified by post‐translational modifications such as phosphorylation. Recent research into the roles of S‐acylation or palmitoylation, the reversible post‐translational modification of proteins with fatty acids, has demonstrated critical functions in the regulation of intracellular signaling in physiology and disease. Palmitoylation, which is catalyzed by the zinc finger Asp‐His‐His‐Cys (zDHHC) family of S‐acyl transferases, has been implicated in trafficking, stability, sorting and binding of proteins to cofactors. However, the roles of palmitoylation in cardiac signal transduction and cardiac pathogenesis are not well understood. In HEK‐293 cells, the Golgi‐localized acyl transferase, zDHHC9, was shown to palmitoylate and induce plasma membrane localization and activation of H‐Ras and N‐Ras, members of the Ras family of membrane‐localized GTPases. Activation of Ras enhances the activity of downstream pathways such as the ERK/MAP kinase pathway and c‐Jun N‐terminal kinases (JNK), which induce pathological cardiac remodeling in the heart. To investigate the potential roles of zDHHC9 in cardiac pathogenesis, we generated a transgenic mouse model with cardiomyocyte‐specific overexpression of zDHHC9 (Tg‐Zdhhc9). These mice exhibited cardiac hypertrophy with increased ventricular wall thickness at 6 months of age. At 8 months of age, Tg‐Zdhhc9 mice showed impaired cardiac contractile function and severe dilated cardiomyopathy. Interestingly, there were no significant differences in palmitoylation of H‐Ras in Tg‐Zdhhc9 hearts compared to control hearts, indicating that zDHHC9‐triggered cardiac hypertrophy may be due to palmitoylation of other substrates in cardiomyocytes. Ongoing work is utilizing unbiased quantitative palmitoyl proteomics to identify novel zDHHC9 substrates that mediate activation of hypertrophic signaling in the cardiomyocytes. Altogether, these data suggest zDHHC9‐mediated palmitoylation contributes to hypertrophic signaling and heart disease.Support or Funding InformationThis work was supported by National Heart, Lung and Blood Institute grant R00‐HL‐36695 (MJB).

Results of the alcohol septal ablation in combination with simultaneous endoprosthesis of coronary arteries in treatment of patients, suffering obstructive hypertrophic cardiomyopathy and concurrent ischemic heart disease

Objective. To study the immediate and remote follow-up results of treatment in patients, suffering obstructive hypertrophic cardiomyopathy and concurrent ischemic heart disease, using the alcohol septal ablation in combination with simultaneous endoprosthesis of coronary arteries.
 Materials and methods. In the investigation were included 129 patients, suffering obstructive hypertrophic cardiomyopathy, to whom the alcohol septal ablation was performed in 2009 - 2018 yrs in M. M. Amosov National Institute of Cardiovascular Surgery. All the patients were distributed into two groups: the first -14 (10.9%) patients with concurrent ischemic heart disease and the second -115 (89.1%) patients without concurrent ischemic heart disease.
 Results. Reduction of the systolic pressure gradient in the exit tract of the left ventriculus, mitral regurgitation, and the functional class characteristic in accordance to criteria of a New-York Association of Cardiologists in both groups in immediate and late periods of observation have appeared statistically proved. In a remote period of follow-up in 13 (92.9%) patients, suffering the ischemic heart disease, a satisfactory hemodynamical result was registered, and in 1 (7.1%) - poor. Conditionally poor results in this group of patients were absent. The patients without an ischemic heart disease (n=107) in accordance to the above mentioned indices were distributed in a follow manner: 74 (69.2%), 28 (26.2%) and 5 (4.7%), accordingly. Statistically significant difference in accordance to hemodynamical results between two groups of patients was absent in immediate and remote periods of follow-up.
 Conclusion. Simultaneous conduction of the alcohol septal ablation in combination with endoprosthesis of coronary arteries in patients, suffering obstructive hypertrophic cardiomyopathy and concurrent ischemic heart disease, constitutes a safe proved combined intervention procedure, which owes good immediate results, persisting in the remote period.

Repurposing an anti-cancer agent for the treatment of hypertrophic heart disease.

Coronary microvascular dysfunction combined with maladaptive cardiomyocyte morphology and energetics is a major contributor to heart failure advancement. Thus, dually enhancing cardiac angiogenesis and targeting cardiomyocyte function to slow, or reverse, the development of heart failure is a logical step towards improved therapy. We present evidence for the potential to repurpose a former anti‐cancer Arg‐Gly‐Asp (RGD)‐mimetic pentapeptide, cilengitide, here used at low doses. Cilengitide targets αvβ3 integrin and this protein is upregulated in human dilated and ischaemic cardiomyopathies. Treatment of mice after abdominal aortic constriction (AAC) surgery with low‐dose cilengitide (ldCil) enhances coronary angiogenesis and directly affects cardiomyocyte hypertrophy with an associated reduction in disease severity. At a molecular level, ldCil treatment has a direct effect on cardiac endothelial cell transcriptomic profiles, with a significant enhancement of pro‐angiogenic signalling pathways, corroborating the enhanced angiogenic phenotype after ldCil treatment. Moreover, ldCil treatment of Angiotensin II‐stimulated AngII‐stimulated cardiomyocytes significantly restores transcriptomic profiles similar to those found in normal human heart. The significance of this finding is enhanced by transcriptional similarities between AngII‐treated cardiomyocytes and failing human hearts. Taken together, our data provide evidence supporting a possible new strategy for improved heart failure treatment using low‐dose RGD‐mimetics with relevance to human disease. © 2019 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

GW29-e0907 Nap1l1 Regulates Cardiac Fibrosis in Hypertrophic Heart Disease by Regulating the TGF-β/Smad Signaling Pathway

Cardiac hypertrophy is a common pathological condition that can progress to myocardial fibrosis and heart failure. We demonstrated that protein levels of nucleosome assembly protein 1-like-1 (Nap1l1) in cardiac tissue from patients with hypertrophic cardiomyopathy (HCM) and mice subjected to

CDC20 regulates cardiac hypertrophy via targeting LC3-dependent autophagy.

Rationale: Sustained cardiac hypertrophy often leads to heart failure (HF). Understanding the regulation of cardiomyocyte growth is crucial for the treatment of adverse ventricular remodeling and HF. Cell division cycle 20 (CDC20) is an anaphase-promoting complex activator that is essential for cell division and tumorigenesis, but the role of CDC20 in cardiac hypertrophy is unknown. We aimed to test whether CDC20 participates in the regulation of pathological cardiac hypertrophy and investigate the underlying mechanism in vitro and in vivo.Methods: Male C57BL/6 mice were administered a recombinant adeno-associated virus serotype 9 (rAAV9) vector expressing CDC20 or a siRNA targeting CDC20 and their respective controls by tail intravenous injection.Results: Microarray analysis showed that CDC20 was significantly upregulated in the heart after angiotensin II infusion. Knockdown of CDC20 in cardiomyocytes and in the heart reduced cardiac hypertrophy upon agonist stimulation or transverse aortic constriction (TAC). Conversely, enforced expression of CDC20 in cardiomyocytes and in the heart aggravated the hypertrophic response. Furthermore, we found that CDC20 directly targeted LC3, a key regulator of autophagy, and promoted LC3 ubiquitination and degradation by the proteasome, which inhibited autophagy leading to hypertrophy. Moreover, knockdown of LC3 or inhibition of autophagy attenuated Ang II-induced cardiomyocyte hypertrophy after deletion of CDC20 in vitro.Conclusions: Our study reveals a novel cardiac hypertrophy regulatory mechanism that involves CDC20, LC3 and autophagy, and suggests that CDC20 could be a new therapeutic target for patients with hypertrophic heart diseases.

Non-coding RNA-linked epigenetic regulation in cardiac hypertrophy.

Cardiac hypertrophy is an adaptive enlargement of myocardium in response to pressure overload caused various pathological insults, which is accompanied by alteration of a complex cascade of signaling pathways. During the hypertrophy process, many changes occur at cellular level including gene reprogramming by turning off chromatin regulators. Studies from the past decade have demonstrated that the abnormal epigenetic modifications, such as DNA methylation, histone modification, and oxidative modification of nucleic acid, could lead to changes in chromosome structure and cardiac dysfunction. Increasing evidence indicates that non-coding RNAs (ncRNAs) have functional significance in modulating the gene expression during those pathological events in the heart. Emerging evidences have highlighted that ncRNAs might serve as a signal for changing the state of chromatin, however, the knowledge about the ncRNA-linked epigenetic regulatory mechanisms in cardiac pathologies is still largely unexplored. In this review, we summarize the current information on association between ncRNAs and epigenetic modifications in cardiac hypertrophy, and we have discussed their crosstalk. In addition, this review provides insights into their therapeutic and diagnostic potential for treating hypertrophic heart disease.

Transthyretin Cardiac Amyloidosis.

Transthyretin (TTR)-related cardiac amyloidosis is a progressive infiltrative cardiomyopathy that mimics hypertensive, hypertrophic heart disease and may go undiagnosed. Transthyretin-derived amyloidosis accounts for 18% of all cases of cardiac amyloidosis. Thus, the study's purpose is to provide a comprehensive review of transthyretin cardiac amyloidosis. Wild-type transthyretin (ATTRwt) protein causes cardiac amyloidosis sporadically, with 25 to 36% of the population older than 80years of age are at risk to develop a slowly progressive, infiltrative amyloid cardiomyopathy secondary to ATTRwt. In contrast, hereditary amyloidosis (ATTRm) is an autosomal dominant inherited disease associated with more than 100 point mutations in the transthyretin gene and has a tendency to affect the heart and nervous system. Up to 4% of African-Americans carry the Val122Ile mutation in the transthyretin gene, the most prevalent cause of hereditary cardiac amyloidosis in the USA. Identifying transthyretin cardiac amyloidosis requires increased awareness of the prevalence, signs and symptoms, and diagnostic tools available for discrimination of this progressive form of cardiomyopathy associated with left ventricular hypertrophy. While there are no FDA-approved medical treatments, investigation is underway on agents to reduce circulating mutated transthyretin.

C1q-TNF-Related Protein-9 Promotes Cardiac Hypertrophy and Failure.

Myocardial endothelial cells promote cardiomyocyte hypertrophy, possibly through the release of growth factors. The identity of these factors, however, remains largely unknown, and we hypothesized here that the secreted CTRP9 (C1q-tumor necrosis factor-related protein-9) might act as endothelial-derived protein to modulate heart remodeling in response to pressure overload. To examine the source of cardiac CTRP9 and its function during pressure overload. CTRP9 was mainly derived from myocardial capillary endothelial cells. CTRP9 mRNA expression was enhanced in hypertrophic human hearts and in mouse hearts after transverse aortic constriction (TAC). CTRP9 protein was more abundant in the serum of patients with severe aortic stenosis and in murine hearts after TAC. Interestingly, heterozygous and especially homozygous knock-out C1qtnf9 (CTRP9) gene-deleted mice were protected from the development of cardiac hypertrophy, left ventricular dilatation, and dysfunction during TAC. CTRP9 overexpression, in turn, promoted hypertrophic cardiac remodeling and dysfunction after TAC in mice and induced hypertrophy in isolated adult cardiomyocytes. Mechanistically, CTRP9 knock-out mice showed strongly reduced levels of activated prohypertrophic ERK5 (extracellular signal-regulated kinase 5) during TAC compared with wild-type mice, while CTRP9 overexpression entailed increased ERK5 activation in response to pressure overload. Inhibition of ERK5 by a dominant negative MEK5 mutant or by the ERK5/MEK5 inhibitor BIX02189 blunted CTRP9 triggered hypertrophy in isolated adult cardiomyocytes in vitro and attenuated mouse cardiomyocyte hypertrophy and cardiac dysfunction in vivo, respectively. Downstream of ERK5, we identified the prohypertrophic transcription factor GATA4, which was directly activated through ERK5-dependent phosphorylation. The upregulation of CTRP9 during hypertrophic heart disease facilitates maladaptive cardiac remodeling and left ventricular dysfunction and might constitute a therapeutic target in the future.

Transthyretin Cardiac Amyloidosis in Black Americans.

Transthyretin-related cardiac amyloidosis is a progressive infiltrative cardiomyopathy that mimics hypertensive and hypertrophic heart disease and often goes undiagnosed. In the United States, the hereditary form disproportionately afflicts black Americans, who when compared with whites with wild-type transthyretin amyloidosis, a phenotypically similar condition, present with more advanced disease despite having a noninvasive method for early identification (genetic testing). Although reasons for this are unclear, this begs to consider the inadequate access to care, societal factors, or a biological basis. In an effort to improve awareness and explore unique characteristics, we review the pathophysiology, epidemiology, and therapeutic strategies for transthyretin amyloidosis and highlight diagnostic pitfalls and clinical pearls for identifying patients with amyloid heart disease.

Hypoxia-driven glycolytic and fructolytic metabolic programs: Pivotal to hypertrophic heart disease

Pathologic cardiac growth is an adaptive response of the myocardium to various forms of systemic (e.g. pressure overload) or genetically-based (e. g. mutations in genes encoding sarcomeric proteins) stress. It represents a key aspect of different types of heart disease including aortic stenosis (AS) and hypertrophic cardiomyopathy (HCM). While many of the pathophysiological and hemodynamical aspects of pathologic cardiac hypertrophy have been uncovered during the last decades, its underlying metabolic determinants are only beginning to come into focus. Here, we review the epidemiological evidence and pathological features of hypertrophic heart disease in AS and HCM and consider in this context the development of microenvironmental tissue hypoxia as a key component of the heart's growth response to pathologic stress. We particularly reflect on recent evidence illustrating how activation of hypoxia-inducible factor (HIF) drives glycolytic and fructolytic metabolic programs to maintain ATP generation and support anabolic growth of the pathologically-stressed heart. Finally we discuss how this metabolic programs, when protracted, deprive the heart of energy leading ultimately to heart failure. This article is part of a Special Issue entitled: Cardiomyocyte Biology: Integration of Developmental and Environmental Cues in the Heart edited by Marcus Schaub and Hughes Abriel.

4-PBA prevents pressure overload-induced myocardial hypertrophy and interstitial fibrosis by attenuating endoplasmic reticulum stress

Our previous study indicated that attenuation of endoplasmic reticulum (ER) stress by administration of 4-phenylbutyric acid (4-PBA) could prevent cardiac rupture and remodeling in a mouse model of myocardial infarction (MI). However, whether 4-PBA is protective in hypertrophic heart disease is unclear. Thus, we tested the therapeutic effect of 4-PBA on pressure-overload induced myocardial hypertrophy. Transverse aortic constriction (TAC) was used to create myocardial hypertrophy in C57BL/6 male mice for 4 weeks. Immediately after surgery, the mice were administrated either 4-PBA (20 mg/kg/day) or 0.9% NaCl by intraperitoneal injection. At the end of 4 weeks, the mice underwent high-resolution echocardiographic imaging. Our results showed that both the left ventricular posterior wall thickness at end systole (LVPWs) and diastole (LVPWd) were increased in the TAC group, compared to control. 4-PBA administration attenuated hypertrophy and decreased the heart weight over body weight ratio. Masson's trichrome staining showed that myocardial interstitial fibrosis and collagen deposition were also decreased by 4-PBA. We next detected the ER stress response in the heart tissues of TAC mice in different time points. Western blotting showed that the expression of ER stress marker, GRP78, CHOP and phosphor-PERK, were persistently increased 4 weeks after TAC. The treatment of 4-PBA inhibited the expression of ER stress markers. We also demonstrated that the 4-PBA at 20 mg/kg/day had no effect on histone 3 deacetylation inhibition, while attenuating ER stress and TAC-induced hypertrophy. These findings suggest that 4-PBA may be a therapeutic strategy to consider in preventing pressure-overload induced myocardial hypertrophy and interstitial fibrosis by selectively attenuating ER stress.

Abstract 30: 4-PBA Prevents TAC-induced Myocardial Hypertrophy and Interstitial Fibrosis by Attenuating ER Stress in Mice

Background: Recently, 4-phenylbutyric acid (4-PBA) has been recognized as a potent ER stress inhibitor and a histone deacetylase inhibitor, but its therapeutic effect in cardiovascular diseases is still not fully understood. Our previous study indicated that attenuation of ER stress by administration of low dosage of 4-PBA (20 mg/kg/d) prevented post-infarction-induced cardiac rupture and remodeling through modulating both cardiac apoptosis and fibrosis in the mouse model of myocardial infarction. However, little is known whether the administration of 4-PBA is effective for hypertrophic heart disease. The aim of this study is therefore to test the therapeutic effect of 4-PBA on pressure-overload induced myocardial hypertrophy. Methods and Results: Transverse aortic constriction (TAC) was used to produce pressure-overload in C57BL/6 male mice for 4 weeks. After surgery, 4-PBA (20mg/kg/d) or 0.9% NaCL was intraperitoneally injected daily. At the end of 4 weeks, the survivals were underwent high-resolution echocardiographic imaging observation. The results showed that the left ventricular posterior wall thickness at end systole (LVPWs) and left ventricular posterior wall thickness at end diastole (LVPWd) were increased in TAC group. Administration of 4-PBA ameliorated this hypertrophic effect. Autopsy also confirmed the anti-hypertrophic effect of 4-PBA. Masson-staining found that there was no difference in perivascular fibrosis between TAC and TAC+4-PBA groups. However, myocardial interstitial fibrosis and collagen deposition were significant decreased by 4-PBA. We finally detected the ER stress and histone acetylation using western blotting. Our results showed that 4-PBA, at the dosage of 20 mg/kg/day, decreased the expression of CHOP and had no effect on histone 3 acetylation. Conclusion: These findings indicate that attenuating ER stress by 4-PBA maybe a promising therapeutic strategy to prevent pressure-overload induced myocardial hypertrophy and interstitial fibrosis.

Phosphodiesterase 9A controls nitric-oxide-independent cGMP and hypertrophic heart disease.

Cyclic guanosine monophosphate (cGMP) is a second messenger molecule that transduces nitric oxide (NO) and natriuretic peptide (NP) coupled signaling, stimulating phosphorylation changes by protein kinase G (PKG). Enhancing cGMP synthesis or blocking its degradation by phosphodiesterase type 5A (PDE5A) protects against cardiovascular disease1,2. However, cGMP stimulation alone is limited by counter-adaptions including PDE upregulation3. Furthermore, though PDE5A regulates NO-generated cGMP4,5, NO-signaling is often depressed by heart disease6. PDEs controlling NP-coupled cGMP remain uncertain. Here we show that cGMP-selective PDE9A7,8 is expressed in mammalian heart including humans, and is upregulated by hypertrophy and cardiac failure. PDE9A regulates NP rather than NO-stimulated cGMP in heart myocytes and muscle, and its genetic or selective pharmacological inhibition protects against pathological responses to neuro-hormones, and sustained pressure-overload stress. PDE9A inhibition reverses pre-established heart disease independent of NO-synthase (NOS) activity, whereas PDE5A inhibition requires active NOS. Transcription factor activation and phospho-proteome analyses of myocytes with each PDE selectively inhibited reveals substantial differential targeting, with phosphorylation changes from PDE5A inhibition being more sensitive to NOS activation. Thus, unlike PDE5A, PDE9A can regulate cGMP signaling independent of the NO-pathway, and its role in stress-induced heart disease suggests potential as a therapeutic target.

The alteration of protein prenylation induces cardiomyocyte hypertrophy through Rheb-mTORC1 signalling and leads to chronic heart failure.

G protein-regulated cell function is crucial for cardiomyocytes, and any deregulation of its gene expression or protein modification can lead to pathological cardiac hypertrophy. Herein, we report that protein prenylation, a lipidic modification of G proteins that facilitates their association with the cell membrane, might control the process of cardiomyocyte hypertrophy. We found that geranylgeranyl diphosphate synthase (GGPPS), a key enzyme involved in protein prenylation, played a critical role in postnatal heart growth by regulating cardiomyocyte size. Cardiac-specific knockout of GGPPS in mice led to spontaneous cardiac hypertrophy, beginning from week 4, accompanied by the persistent enlargement of cardiomyocytes. This hypertrophic effect occurred by altered prenylation of G proteins. Evaluation of the prenylation, membrane association and hydrophobicity showed that Rheb was hyperactivated and increased mTORC1 signalling pathway after GGPPS deletion. Protein farnesylation or mTORC1 inhibition blocked GGPPS knockdown-induced mTORC1 activation and suppressed the larger neonatal rat ventricle myocyte size and cardiomyocyte hypertrophy in vivo, demonstrating a central role of the FPP-Rheb-mTORC1 axis for GGPPS deficiency-induced cardiomyocyte hypertrophy. The sustained cardiomyocyte hypertrophy progressively provoked cardiac decompensation and dysfunction, ultimately causing heart failure and adult death. Importantly, GGPPS was down-regulated in the hypertrophic hearts of mice subjected to transverse aortic constriction (TAC) and in failing human hearts. Moreover, HPLC-MS/MS detection revealed that the myocardial farnesyl diphosphate (FPP):geranylgeranyl diphosphate (GGPP) ratio was enhanced after pressure overload. Our observations conclude that the alteration of protein prenylation promotes cardiomyocyte hypertrophic growth, which acts as a potential cause for pathogenesis of heart failure and may provide a new molecular target for hypertrophic heart disease clinical therapy.

Abstract 19428: TRAF3IP2 Mediates Aldosterone-induced Cardiac Hypertrophy and Fibrosis

Background: Aldosterone (Aldo) is a key regulator of blood pressure and electrolyte balance. Aldo/salt has been shown to induce oxidative stress, inflammation, cardiac hypertrophy and fibrosis. TRAF3 interacting protein 2 (TRAF3IP2) is a cytoplasmic redox-sensitive adaptor molecule and an upstream regulator of NF-κB and AP-1. It plays a critical role in the regulation of various proinflammatory cytokines that exert prohypertrophic and profibrotic effects. Therefore, we hypothesized that TRAF3IP2 is a critical mediator of Aldo/salt-induced cardiac hypertrophy and fibrosis. Methods: TRAF3IP2-null and wild type (WT) mice (male, 12-13 weeks) were infused continuously with Aldo for 4 weeks via mini-osmotic pumps (0.2 mg/Kg/day; n = 6-8). Mice were fed 1% NaCl in drinking water. Salt alone served as control. Systolic blood pressure (SBP) was measured by tail-cuff plethysmography, myocardial function by echocardiography, cardiac hypertrophy by heart weight to body weight ratios, cardiac fibrosis by trichrome Gomori, and gene and protein expression by RT-qPCR, immunoblotting and ELISA. Results: Aldo/salt elevated SBP to a similar extent in both TRAF3IP2-null and WT mice. Aldo/salt upregulated TRAF3IP2 expression in left ventricular homogenates from WT mice, and TRAF3IP2 gene deletion (vs. WT) blunted cardiac hypertrophy by 54% (p < 0.05), suppressed ANP expression by 3.5 fold (p < 0.05), prevented concentric LV remodeling (decreased LVPWs; 93%; p < 0.01, LVPWd; 95%; p < 0.05, LVAWs; 29.8%; p < 0.05 and LVAWd; 26.2%, and increased LVIDs; 19.2%; p < 0.01 and LVIDd; 8.53%) and markedly reduced both interstitial and perivascular fibrosis. Further, TRAF3IP2 gene deletion inhibited Aldo/salt-induced p65 and c-Jun activation, and expression of inflammatory cytokine (IL-18 and IL-6), matrix metalloproteinase (MMP2) and extracellular matrix proteins (collagen Iα1 and IIIα1). TRAF3IP2 gene deletion also blunted mRNA and protein expression of lysyl oxidase, an enzyme involved in collagen crosslinking. Conclusions: TRAF3IP2 gene deletion blunts Aldo/salt-induced cardiac hypertrophy and fibrosis by inhibiting proinflammatory, prohypertrophic, and profibrotic effects, signifying its potential as a therapeutic target in hypertrophic heart diseases.

10Chronic kidney disease - an independent risk factor for sustained VT/VF in heart failure patients with primary prevention CRT-D devices

Introduction: Patients with impaired left ventricular (LV) function and heart failure are at increased risk of sudden cardiac death (SCD) due to ventricular arrhythmia (VA). Identifying the cohort at highest risk who benefit from ICD therapy is incompletely understood. Chronic kidney disease (CKD) has been shown to be a poor prognostic factor in patients with primary prevention ICDs but has not been formally assessed in patients with primary prevention CRT devices apart from sub-group analyses. Patients implanted with primary prevention CRT-D devices implanted over 6 years at a single-centre, were retrospectively studied to test the hypothesis that CKD is an independent risk factor for VA. Methods: All patients with CRT-D devices implanted between January 2005 and December 2010 were included, except those with hypertrophic cardiomyopathy (HCM), ion channelopathies and congenital heart disease. Secondary prevention patients were excluded. The cohort was divided into 2 groups- CKD group (patients with eGFR 60mls/min/1.73m2) based on blood results immediately prior to implantation. Evidence of VA during follow up was ascertained from device follow up and clinic consultation records. Results: A total of 155 patients were included, 80 in the CKD group and 75 patients in the non-CKD group. Mean follow up was 50.5 months (range 1-106). LV ejection fraction, NYHA class, gender, use of BB, ACE inhibitor and Amiodarone were similar between groups. The CKD group was older (mean 69.2yrs vs 61.4yrs, P<0.05) with a higher proprortion of patients with ischaemic cardiomyopathy (58% vs 38% P<0.05). 37.5% of CKD patients (30/80) developed VA resulting in appropriate device therapy compared to 21.3% (16/75) in the non-CKD group (p<0.05). Kaplan-Meier (KM) survival probability analysis showed a significant difference in the 5 year VT/VF event free survival between the two groups (63.4% vs 88%, CKD vs non-CKD group) with progression in survival difference over time (Log rank 0.003). Mean survival time was 59.7 months in the CKD group (CI 50.3-69.1 months) vs 81.2 months (CI 73.1-89.3 months) in the non-CKD arm. A cox proportional hazard model (backward stepwise conditional method) identified eGFR <60 as the only independent predictor of sustained VA occurrence in this cohort (p<0.003). Despite this, there was no significant difference in the mortality survival curves between the two groups (Log rank 0.34) Conclusions: >50% of patients with primary prevention CRT-D devices have CKD and CKD is an independent risk factor for developing ventricular arrhythmia resulting in device therapy in this study. The presence of CKD, however, did not influence mortality. Results suggest the presence of CKD should be incorporated into decision models for identifying patients with LV dysfunction likely to benefit from device therapy and used to identify those at greater risk of receiving ICD therapies after implant. ![Graphic][1] [1]: /embed/inline-graphic-1.gif

DIFFERENTIAL DIAGNOSIS OF HYPERTROPHIC CARDIOMYOPATHY AND HYPERTENSIVE HEART DISEASE BY EXERCISE TESTING

Aim. To assess the effectiveness of a bicycle ergometer exercise test in differentiation of hypertrophic cardiomyopathy (HCM) and hypertensive heart disease (HHD). Material and methods. 42 patients with HCM (mean age 49,8±15,3-28 male) and 25 patients with HHD (mean age 47,0±12,4-16 male) were studied. All patients underwent upright bicycle ergometer exercise test after withdrawal of drug therapy. Results. It is well-known that abnormal blood pressure response (ABPR) and ST depression with angina during exercise are the criteria for the termination of test (RTT) and are the HCM attributes (after ruling out the coronary atherosclerosis by coronarography). With the use of nonparametric statistics we found significant difference between HCM and HHD in systolic blood pressure (SBP) at the end of the test (174,6±30,8 and 210,4±21,1 mmHg; p=0,000006), time recovery after test (TR) (10,0±4,0 and 7,1±1,6 min; p=0,007), breathlessness as a RTT (38,4% and 4%, p=0,022); extrasystole as a RTT (12,5% and 0%). With the use of logistic regression we found a dependency for differential diagnosis of HCM and HHD: Diagnosis = 0,41*SBPe-40,79-3,65*TR-13,34*BR-41,87*EXT-1000*0 TH . Where SBPe is SBP at the end of the test; TR equals 1 if breathlessness was the RTT and 0 otherwise; EXT equals 1 if extrasystole was the RTT and 0 otherwise; OTH equals 1 if ABPR, ST depression or stenocardia were the RTT and 0 otherwise. Diagnosis is greater than 0 for HHD and less than 0 for HCM patients. For all patients included in our study the dependency provides correct result. Conclusion. The exercise testing gives useful information and can be applied for differential diagnosis of HCM and HDD.

Macrophage MicroRNA-155 Promotes Cardiac Hypertrophy and Failure

Cardiac hypertrophy and subsequent heart failure triggered by chronic hypertension represent major challenges for cardiovascular research. Beyond neurohormonal and myocyte signaling pathways, growing evidence suggests inflammatory signaling pathways as therapeutically targetable contributors to this process. We recently reported that microRNA-155 is a key mediator of cardiac inflammation and injury in infectious myocarditis. Here, we investigated the impact of microRNA-155 manipulation in hypertensive heart disease. Genetic loss or pharmacological inhibition of the leukocyte-expressed microRNA-155 in mice markedly reduced cardiac inflammation, hypertrophy, and dysfunction on pressure overload. These alterations were macrophage dependent because in vivo cardiomyocyte-specific microRNA-155 manipulation did not affect cardiac hypertrophy or dysfunction, whereas bone marrow transplantation from wild-type mice into microRNA-155 knockout animals rescued the hypertrophic response of the cardiomyocytes and vice versa. In vitro, media from microRNA-155 knockout macrophages blocked the hypertrophic growth of stimulated cardiomyocytes, confirming that macrophages influence myocyte growth in a microRNA-155-dependent paracrine manner. These effects were at least partly mediated by the direct microRNA-155 target suppressor of cytokine signaling 1 (Socs1) because Socs1 knockdown in microRNA-155 knockout macrophages largely restored their hypertrophy-stimulating potency. Our findings reveal that microRNA-155 expression in macrophages promotes cardiac inflammation, hypertrophy, and failure in response to pressure overload. These data support the causative significance of inflammatory signaling in hypertrophic heart disease and demonstrate the feasibility of therapeutic microRNA targeting of inflammation in heart failure.

Abstract 181: Cardiac Hypertrophy And Heart Failure In K-channel Ancillary Subunit Depleted Mice

Down regulation of cardiac K+ currents has been described in hypertrophic heart disease and heart failure. However, so far no mutations in potassium channel genes have been found in patients with cardiac hypertrophy/heart failure. It therefore remains controversial whether K+ current down regulation represents a primary cause of cardiac hypertrophy/heart failure or epiphenomena. KCNE2 is a voltage gated potassium channel ancillary subunit that is associated with inherited and acquired long QT syndrome. We recently developed KCNE2-/- mice. KCNE2-/- mice have normal cardiac morphology and function at 3-6 months of age despite a repolarization defect caused by disruption of IKslow, 1 and Ito, f. However, aged KCNE2-/- mice (12 months and older) develop significant cardiac hypertrophy and severe heart failure assessed by echocardiography, isolated heart (Langendorff) and reduced cellular shortening (IonOptix). Furthermore, after Angiotensin II stimulation 3-6 months old KCNE2-/- mice also develop significant cardiac hypertrophy and fibrosis compared to age-matched KCNE2+/+ siblings. Taqman PCR revealed molecular remodelling in hypertrophied failing KCNE2-/- hearts with induction of the fetal gene program (ANF re-expression), significant up regulation of Sodium-Calcium Exchanger (NCX) and significant down regulation of phospholamban. Alterations in Calcium handling proteins were also recapitulated on protein level by Western Blotting. Furthermore, electrophysiological studies by patch clamp analysis of isolated cardiomyocytes revealed a decrease in current densities of the L-type Ca2+-current and a strongly diminished response to isoprenaline stimulation in hypertrophied failing KCNE2-/- cardiomyocytes. We therefore conclude that primary disruption of repolarizing Kv currents by KCNE2 deletion leads to altered Calcium handling and consecutive induction of cardiac hypertrophy/heart failure.