Abstract 14309: A Novel Fibroblast Activation Inhibitor, NM922, Attenuates Maladaptive Fibrotic Remodeling to Preserve Cardiac Function Following the Onset of Heart Failure

Background: Cardiac fibroblasts are critical mediators of fibrotic remodeling in the failing heart. These maladaptive structural changes can worsen cardiac function accelerating the progression to decompensated heart failure (HF). We investigated the effects of a novel inhibitor of the conversion of normal fibroblast to the myofibroblast phenotype in the setting of pressure overload induced HF. Methods: Male C57BL/6J mice (10 wks) were subjected to transverse aortic constriction (TAC; 27 g needle) and NM922 (NovoMedix, LLC50 mg/kg/d i.p.) or VEH (DMSO + HS-15) was administered daily starting at 6 wks post TAC. Echocardiography was assessed at baseline and for 16 wks post TAC. At the 16 wk endpoint, mice were sacrificed and hearts were collected for biochemical and molecular assessment. Results: NM922 significantly attenuated TAC-induced left ventricular (LV) dilation at 16 wks post TAC (LVEDD: 3.5 ± 0.1 vs. 4.5 ± 0.2 mm, p < 0.01; LVESD: 2.5 ± 0.2 vs. 3.8 ± 0.3 mm, p < 0.01) compared to VEH. NM922 treated mice displayed reduced wall thickening (LVPWd: 1.0 ± 0.03 vs. 1.2 ± 0.05 mm; p < 0.05) at 10 wks post TAC compared to VEH. LV ejection fraction (LVEF) was preserved in NM922 treated mice at 8-16 wks post TAC compared to VEH (*p < 0.05; **p < 0.001) compared to VEH. Treatment with NM922 resulted in reductions in heart (8.5 ± 0.5 vs. 12.0 ± 0.9 mg/mm; p < 0.01) and lung (8.2 ± 0.3 vs. 11.5 ± 0.6 mg/mm; p < 0.0001) weights compared to VEH. Picrosirius Red staining revealed that NM922 reduced cardiac interstitial collagen volume fraction by 50% (p < 0.05 vs. VEH). Circulating BNP levels trended toward lower (p = 0.08) in the NM922 mice when compared to VEH. Conclusion: Chronic treatment with NM922 following the onset of cardiac hypertrophy and HF resulted in attenuated myocardial collagen formation and adverse remodeling with preservation of LVEF. Future studies are aimed at further elucidation of the molecular and cellular mechanisms by which this novel agent protects the failing heart.

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An Electromechanical Left Ventricular Wedge Model to Study the Effects of Deformation on Repolarization during Heart Failure

BioMed Research International ◽

10.1155/2015/465014 ◽

2015 ◽

Vol 2015 ◽

pp. 1-12 ◽

Cited By ~ 1

Author(s):

B. M. Rocha ◽

E. M. Toledo ◽

L. P. S. Barra ◽

R. Weber dos Santos

Keyword(s):

Heart Failure ◽

Structural Changes ◽

Left Ventricular ◽

Cardiac Contraction ◽

Strongly Coupled ◽

Electromechanical Model ◽

Failing Heart ◽

Dispersion Of Repolarization ◽

Failure Conditions ◽

Transmural Dispersion

Heart failure is a major and costly problem in public health, which, in certain cases, may lead to death. The failing heart undergo a series of electrical and structural changes that provide the underlying basis for disturbances like arrhythmias. Computer models of coupled electrical and mechanical activities of the heart can be used to advance our understanding of the complex feedback mechanisms involved. In this context, there is a lack of studies that consider heart failure remodeling using strongly coupled electromechanics. We present a strongly coupled electromechanical model to study the effects of deformation on a human left ventricle wedge considering normal and hypertrophic heart failure conditions. We demonstrate through a series of simulations that when a strongly coupled electromechanical model is used, deformation results in the thickening of the ventricular wall that in turn increases transmural dispersion of repolarization. These effects were analyzed in both normal and failing heart conditions. We also present transmural electrograms obtained from these simulations. Our results suggest that the waveform of electrograms, particularly the T-wave, is influenced by cardiac contraction on both normal and pathological conditions.

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Stanniocalcin-1 is a naturally occurring L-channel inhibitor in cardiomyocytes: relevance to human heart failure

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.01071.2002 ◽

2003 ◽

Vol 285 (1) ◽

pp. H442-H448 ◽

Cited By ~ 45

Author(s):

David Sheikh-Hamad ◽

Roger Bick ◽

Gang-Yi Wu ◽

Birgitte Mønster Christensen ◽

Peter Razeghi ◽

...

Keyword(s):

Heart Failure ◽

Structural Changes ◽

Cardiac Tissue ◽

Heart Tissue ◽

Left Ventricular ◽

Calcium Currents ◽

Human Heart Failure ◽

Rat Cardiomyocytes ◽

Failing Heart ◽

Mechanical Unloading

Cardiomyocytes of the failing heart undergo profound phenotypic and structural changes that are accompanied by variations in the genetic program and profile of calcium homeostatic proteins. The underlying mechanisms for these changes remain unclear. Because the mammalian counterpart of the fish calcium-regulating hormone stanniocalcin-1 (STC1) is expressed in the heart, we reasoned that STC1 might play a role in the adaptive-maladaptive processes that lead to the heart failure phenotype. We examined the expression and localization of STC1 in cardiac tissue of patients with advanced heart failure before and after mechanical unloading using a left ventricular assist device (LVAD), and we compared the results with those of normal heart tissue. STC1 protein is markedly upregulated in cardiomyocytes and arterial walls of failing hearts pre-LVAD and is strikingly reduced after LVAD treatment. STC1 is diffusely expressed in cardiomyocytes, although nuclear predominance is apparent. Addition of recombinant STC1 to the medium of cultured rat cardiomyocytes slows their endogenous beating rate and diminishes the rise in intracellular calcium with each contraction. Furthermore, using whole cell patch-clamp studies in cultured rat cardiomyocytes, we find that addition of STC1 to the bath causes reversible inhibition of transmembrane calcium currents through L-channels. Our data suggest differential regulation of myocardial STC1 protein expression in heart failure. In addition, STC1 may regulate calcium currents in cardiomyocytes and may contribute to the alterations in calcium homeostasis of the failing heart.

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A novel fibroblast activation inhibitor attenuates left ventricular remodeling and preserves cardiac function in heart failure

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00603.2017 ◽

2018 ◽

Vol 315 (3) ◽

pp. H563-H570 ◽

Cited By ~ 4

Author(s):

Jessica M. Bradley ◽

Pablo Spaletra ◽

Zhen Li ◽

Thomas E. Sharp ◽

Traci T. Goodchild ◽

...

Keyword(s):

Heart Failure ◽

Left Ventricular Ejection Fraction ◽

Ejection Fraction ◽

Cardiac Function ◽

Left Ventricular ◽

Left Ventricular Ejection ◽

Transverse Aortic Constriction ◽

Aortic Constriction ◽

Ventricular Ejection Fraction ◽

Failing Heart

Cardiac fibroblasts are critical mediators of fibrotic remodeling in the failing heart and transform into myofibroblasts in the presence of profibrotic factors such as transforming growth factor-β. Myocardial fibrosis worsens cardiac function, accelerating the progression to decompensated heart failure (HF). We investigated the effects of a novel inhibitor (NM922; NovoMedix, San Diego, CA) of the conversion of normal fibroblasts to the myofibroblast phenotype in the setting of pressure overload-induced HF. NM922 inhibited fibroblast-to-myofibroblast transformation in vitro via a reduction of activation of the focal adhesion kinase-Akt-p70S6 kinase and STAT3/4E-binding protein 1 pathways as well as via induction of cyclooxygenase-2. NM922 preserved left ventricular ejection fraction ( P < 0.05 vs. vehicle) and significantly attenuated transverse aortic constriction-induced LV dilation and hypertrophy ( P < 0.05 compared with vehicle). NM922 significantly ( P < 0.05) inhibited fibroblast activation, as evidenced by reduced myofibroblast counts per square millimeter of tissue area. Picrosirius red staining demonstrated that NM922 reduced ( P < 0.05) interstitial fibrosis compared with mice that received vehicle. Similarly, NM922 hearts had lower mRNA levels ( P < 0.05) of collagen types I and III, lysyl oxidase, and TNF-α at 16 wk after transverse aortic constriction. Treatment with NM922 after the onset of cardiac hypertrophy and HF resulted in attenuated myocardial collagen formation and adverse remodeling with preservation of left ventricular ejection fraction. Future studies are aimed at further elucidation of the molecular and cellular mechanisms by which this novel antifibrotic agent protects the failing heart. NEW & NOTEWORTHY Our data demonstrated that a novel antifibrotic agent, NM922, blocks the activation of fibroblasts, reduces the formation of cardiac fibrosis, and preserves cardiac function in a murine model of heart failure with reduced ejection fraction.

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Experimentally observed phenomena on cardiac energetics in heart failure emerge from simulations of cardiac metabolism

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.0812768106 ◽

2009 ◽

Vol 106 (17) ◽

pp. 7143-7148 ◽

Cited By ~ 47

Author(s):

Fan Wu ◽

Jianyi Zhang ◽

Daniel A. Beard

Keyword(s):

Heart Failure ◽

Cardiac Function ◽

Negative Impact ◽

Adenine Nucleotide ◽

Energy State ◽

Left Ventricular ◽

Emergent Properties ◽

Resonance Spectroscopy ◽

Failing Heart ◽

Adenine Nucleotide Pool

The failing heart is hypothesized to suffer from energy supply inadequate for supporting normal cardiac function. We analyzed data from a canine left ventricular hypertrophy model to determine how the energy state evolves because of changes in key metabolic pools. Our findings—confirmed by in vivo 31P-magnetic resonance spectroscopy—indicate that the transition between the clinically observed early compensatory phase and heart failure and the critical point at which the transition occurs are emergent properties of cardiac energy metabolism. Specifically, analysis reveals a phenomenon in which low and moderate reductions in metabolite pools have no major negative impact on oxidative capacity, whereas reductions beyond a critical tipping point lead to a severely compromised energy state. The transition point corresponds to reductions in the total adenine nucleotide pool (TAN) of ≈30%, corresponding to the reduction observed in humans in heart failure [Ingwall JS, Weiss RG (2004) Is the failing heart energy starved? On using chemical energy to support cardiac function. Circ Res 95(2):135–145]. At given values of TAN and the total exchangeable phosphate pool during hypertrophic remodeling, the creatine pool attains a value that is associated with optimal ATP hydrolysis potential. Thus, both increases and decreases to the creatine pool are predicted to result in diminished energetic state unless accompanied by appropriate simultaneous changes in the other pools.

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Direct Myocardial Implantation of Human Fetal Stem Cells in Heart Failure Patients: Long-term Results

The Heart Surgery Forum ◽

10.1532/hsf98.20091130 ◽

2010 ◽

Vol 13 (1) ◽

pp. 31 ◽

Cited By ~ 13

Author(s):

Federico Benetti ◽

Ernesto Pe�herrera ◽

Teodoro Maldonado ◽

Yan Duarte Vera ◽

Valvanur Subramanian ◽

...

Keyword(s):

Heart Failure ◽

Stem Cells ◽

Cardiac Function ◽

Nyha Class ◽

Left Ventricular ◽

Long Term Results ◽

Walk Test ◽

The Mean ◽

6 Minute Walk Test ◽

Minute Walk

Background: End-stage heart failure (HF) is refractory to current standard medical therapy, and the number of donor hearts is insufficient to meet the demand for transplantation. Recent studies suggest autologous stem cell therapy may regenerate cardiomyocytes, stimulate neovascularization, and improve cardiac function and clinical status. Although human fetal-derived stem cells (HFDSCs) have been studied for the treatment of a variety of conditions, no clinical studies have been reported to date on their use in treating HF. We sought to determine the efficacy and safety of HFDSC treatment in HF patients.Methods and Results: Direct myocardial transplantation of HFDSCs by open-chest surgical procedure was performed in 10 patients with HF due to nonischemic, nonchagasic dilated cardiomyopathy. Before and after the procedure, and with no changes in their preoperative doses of medications (digoxin, furosemide, spironolactone, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, betablockers), patients were assessed for New York Heart Association (NYHA) class, performance in the exercise tolerance test (ETT), ejection fraction (EF), left ventricular end-diastolic dimension (LVEDD) via transthoracic echocardiography, performance in the 6-minute walk test, and performance in the Minnesota congestive HF test. All 10 patients survived the operation. One patient had a stroke 3 days after the procedure, and although she later recovered, she was unable to perform the follow-up tests. Another male patient experienced pericardial effusion 3 weeks after the procedure. Although it resolved spontaneously, the patient abandoned his control tests and died 5 months after the procedure. An autopsy of the myocardium suggested that new young cells were present in the cardiomyocyte mix. At 40 months, the mean (SD) NYHA class decreased from 3.4 0.5 to 1.33 0.5 (P = .001); the mean EF increased 31%, from 26.6% 4% to 34.8% 7.2% (P = .005); and the mean ETT increased 291.3%, from 4.25 minutes to 16.63 minutes (128.9% increase in metabolic equivalents, from 2.46 to 5.63) (P < .0001); the mean LVEDD decreased 15%, from 6.85 0.6 cm to 5.80 0.58 cm (P < .001); mean performance in the 6-minute walk test increased by 43.2%, from 251 113.1 seconds to 360 0 seconds (P = .01); the mean distance increased 64.4%, from 284.4 144.9 m to 468.2 89.8 m (P = .004); and the mean result in the Minnesota test decreased from 71 27.3 to 6 5.9 (P < .001).Conclusion: Although these initial findings suggest direct myocardial implantation of HFDSCs is feasible and improves cardiac function in HF patients at 40 months, more clinical research is required to confirm these observations.

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The link between left ventricular extracellular volume determined by T1 myocardial mapping and gut microbiota composition in individuals with heart failure and preserved ejection fraction

European Heart Journal ◽

10.1093/ehjci/ehaa946.0864 ◽

2020 ◽

Vol 41 (Supplement_2) ◽

Author(s):

A.N Kaburova ◽

O.M Drapkina ◽

S.M Uydin ◽

M.V Vishnyakova ◽

M.S Pokrovskaya ◽

...

Keyword(s):

Heart Failure ◽

Ejection Fraction ◽

Gut Microbiota ◽

Myocardial Fibrosis ◽

Volume Fraction ◽

Extracellular Volume ◽

Left Ventricular ◽

Diffuse Myocardial Fibrosis ◽

Rrna Gene ◽

Preserved Ejection Fraction

Abstract Introduction Heart failure with preserved ejection fraction (HFpEF) represents a major challenge in modern cardiology. As described previously, in HFpEF comorbidities promote a systemic inflammatory state, leading to diffuse myocardial fibrosis resulting in myocardial stiffening. Gut dysbiosis which is considered as the novel source of chronic systemic inflammation has been actively investigated as the risk factor for the development and aggravation of cardiovascular diseases including heart failure. Cardiac magnetic resonance T1-mapping is a novel tool, which allows noninvasive quantification of the extracellular space and diffuse myocardial fibrosis. Moreover, the extracellular volume (ECV) fraction can be calculated, providing information on the relative expansion of the extracellular matrix, thus being a noninvasive alternative to myocardial biopsy studies. Purpose The research was aimed at investigating the correlation between the left ventricular ECV and gut microbial genera in patients with HFpEF. Methods 42 patients with confirmed HF-pEF (mediana and interquartile range of age 67 [64; 72] years, 47% men, body mass index <35 kg/m2 with no history of myocardial infarction or diabetes mellitus) were enrolled in the study. The patients underwent transthoracic echocardiography with Doppler study, HF-pEF was confirmed according to the recent ESC guidelines (based on E/e' ratio, N-terminal pro-B type natriuretic peptide >125 pg/ml and symptoms of heart failure). The intestinal microbiome was investigated using high-throughput sequencing of bacterial 16S rRNA gene. As the last step of research T1-myocardial mapping with the modified look-locker inversion-recovery protocol (MOLLI) sequence at 1.5 Tesla was performed to assess left ventricular extracellular volume fraction. Results The mean±std in ECV was 31.02±4.4%. The relative abundance (%) of the most prevalent phyla in gut microbiota was 48±22.5 for Firmicutes, 47.4±22.8 for Bacteroidetes and 1.5 [1.5; 2.5] for Proteobacteria. The analysis showed significant negative correlations between ECV and the following bacterial genera: Faecalibacterium (r=−0.35), Blautia (r=−0.43), Lachnoclostridium (r=−0.32). Moreover ECV positively correlated with Holdemania (r=0.4), Victivallis (r=0.38), Dehalobacterium (r=0.38), Enterococcus (r=0.33) and Catabacter (r=0.32). All correlation values with p<0.05. Conclusion We discovered both negative and positive significant correlations between ECV – the non-invasive marker of myocardial fibrosis and several bacterial genera, which may have negative impact on myocardial remodeling in HF-pEF. Funding Acknowledgement Type of funding source: None

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A Randomized Controlled Trial to Study the Effect of Yoga Therapy on Cardiac Function and N Terminal Pro BNP in Heart Failure

Integrative Medicine Insights ◽

10.4137/imi.s13939 ◽

2014 ◽

Vol 9 ◽

pp. IMI.S13939 ◽

Cited By ~ 12

Author(s):

Bandi Hari Krishna ◽

Pravati Pal ◽

G. K. Pal ◽

J. Balachander ◽

E. Jayasettiaseelon ◽

...

Keyword(s):

Heart Failure ◽

Cardiac Function ◽

Medical Therapy ◽

Left Ventricular ◽

Left Ventricular Ejection ◽

Control Group ◽

Tei Index ◽

Ventricular Ejection Fraction ◽

Yoga Therapy ◽

Standard Medical Therapy

Aims The purpose of this study was to evaluate whether yoga training in addition to standard medical therapy can improve cardiac function and reduce N terminal pro B-type natriuretic peptide (NT pro BNP) in heart failure (HF). Methods 130 patients were recruited and randomized into two groups: Control Group (CG) ( n = 65), Yoga Group (YG). In YG, 44 patients and in CG, 48 patients completed the study. Cardiac function using left ventricular ejection fraction (LVEF), myocardial performance index (Tei index), and NT pro BNP, a biomarker of HF, was assessed at baseline and after 12 weeks. Result Improvement in LVEF, Tei index, and NT pro BNP were statistically significant in both the groups. Furthermore, when the changes in before and after 12 weeks were in percentage, LVEF increased 36.88% in the YG and 16.9% in the CG, Tei index was reduced 27.87% in the YG and 2.79% in the CG, NT pro BNP was reduced 63.75% in the YG and 10.77% in the CG. The between group comparisons from pre to post 12 weeks were significant for YG improvements (LVEF, P < 0.01, Tei index, P < 0.01, NT pro BNP, P < 0.01). Conclusion These results indicate that the addition of yoga therapy to standard medical therapy for HF patients has a markedly better effect on cardiac function and reduced myocardial stress measured using NT pro BNP in patients with stable HF.

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Long-term levosimendan treatment improves systolic function and myocardial relaxation in mice with cardiomyocyte-specific disruption of the Serca2 gene

Journal of Applied Physiology ◽

10.1152/japplphysiol.01044.2012 ◽

2013 ◽

Vol 115 (10) ◽

pp. 1572-1580 ◽

Cited By ~ 7

Author(s):

Vigdis Hillestad ◽

Frank Kramer ◽

Stefan Golz ◽

Andreas Knorr ◽

Kristin B. Andersson ◽

...

Keyword(s):

Gene Expression ◽

Heart Failure ◽

Cardiac Function ◽

Diastolic Dysfunction ◽

Systolic Function ◽

Cytosolic Calcium ◽

Left Ventricular ◽

Pressure Measurements ◽

Human Heart Failure

In human heart failure (HF), reduced cardiac function has, at least partly, been ascribed to altered calcium homeostasis in cardiomyocytes. The effects of the calcium sensitizer levosimendan on diastolic dysfunction caused by reduced removal of calcium from cytosol in early diastole are not well known. In this study, we investigated the effect of long-term levosimendan treatment in a murine model of HF where the sarco(endo)plasmatic reticulum ATPase ( Serca) gene is specifically disrupted in the cardiomyocytes, leading to reduced removal of cytosolic calcium. After induction of Serca2 gene disruption, these mice develop marked diastolic dysfunction as well as impaired contractility. SERCA2 knockout (SERCA2KO) mice were treated with levosimendan or vehicle from the time of KO induction. At the 7-wk end point, cardiac function was assessed by echocardiography and pressure measurements. Vehicle-treated SERCA2KO mice showed significantly diminished left-ventricular (LV) contractility, as shown by decreased ejection fraction, stroke volume, and cardiac output. LV pressure measurements revealed a marked increase in the time constant (τ) of isovolumetric pressure decay, showing impaired relaxation. Levosimendan treatment significantly improved all three systolic parameters. Moreover, a significant reduction in τ toward normalization indicated improved relaxation. Gene-expression analysis, however, revealed an increase in genes related to production of the ECM in animals treated with levosimendan. In conclusion, long-term levosimendan treatment improves both contractility and relaxation in a heart-failure model with marked diastolic dysfunction due to reduced calcium transients. However, altered gene expression related to fibrosis was observed.

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Abstract 2883: Retroinfusion-facilitated Inotropic AAV9-S100A1 Gene Therapy Restores Global Cardiac Function In A Clinically Relevant Pig Heart Failure Model

Circulation ◽

10.1161/circ.118.suppl_18.s_792 ◽

2008 ◽

Vol 118 (suppl_18) ◽

Author(s):

Sven T Pleger ◽

Changguang Shan ◽

Jan Kziencek ◽

Oliver Mueller ◽

Raffi Bekeredjian ◽

...

Keyword(s):

Heart Failure ◽

Gene Therapy ◽

Gene Transfer ◽

Cardiac Function ◽

Left Ventricular ◽

Large Animal ◽

Circumflex Artery ◽

Cell Counts ◽

Clinical Conditions

Background: Cardiac expression of the Ca-dependent inotropic protein S100A1 is decreased in human end-stage heart failure (HF) and cardiomyocyte-targeted viral-based S100A1 gene transfer rescued failing myocardium in small animal models in vivo and in vitro via improved systolic and diastolic sarcoplasmic reticulum Ca-handling. We therefore hypothesized that cardioselective AAV9-S100A1 gene therapy will improve cardiac performance in a large animal experimental HF model under clinical conditions. Methods and Results: Left ventricular (LV) posterolateral myocardial infarction (MI) was induced in pigs by occlusion of the left coronary circumflex artery and resulted in LV failure (HF) 2 weeks post-MI reflected by a 40% and 27% reduction in LV +dp/dt max. and EF, respectively, as assessed by LV catheterization and echocardiography. Post-MI HF pigs were then randomized for retroinfusion of AAV9-luciferase (luc; n=6, 1.5×10 13 total viral particles, tvp) and AAV9-S100A1 (S100A1; n=6, 1.5×10 13 tvp) driven by a cardioselective promoter via the anterior cardiac vein while the left anterior descending artery was temporarily occluded. 14 weeks after cardiac gene transfer, the S100A1-treated HF group showed significantly enhanced S100A1 protein expression (+46.7±17.9%, P<0.05 vs. control groups) in targeted remote LV myocardium and improved indices of cardiac function and remodeling (luc vs. S100A1: +dp/dtmax: 983±81 vs. 1526±83 mmHg/s, EF: 39±2.1 vs. 61±3.7 %, P<0.05 S100A1 vs. luc, LV endsystolic diameter: luc 4.45±0.1 vs. S100A1 3.43 ±0.1 cm, P<0.05 S100A1 vs. luc, HR: 72±4 vs. 69±2, beats/min, P=n.s. S100A1 vs. luc). Importantly, analyses of renal, hepatic and hematopoetic function showed no alteration as assessed by unchanged transaminases, retention values and white blood cell counts compared to sham pigs. Conclusions: Our translational study provides proof of concept that AAV9-S100A1 based HF gene therapy is feasible and restores cardiac function in a large animal HF model under clinical conditions. Next, certified toxicological analysis and different AAV9-S100A1 dosage protocols will be assessed to eventually advance to first phase I/II clinical studies determining therapeutic efficiency of cardiac S100A1 gene therapy in HF patients.

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Abstract 1213: Cardiac Overexpression of Epac1 in Transgenic Mice Protects Heart from Lipopolysaccharide-induced Cardiac Dysfunction and Inhibits JAK-STAT Pathway

Circulation ◽

10.1161/circ.116.suppl_16.ii_246-b ◽

2007 ◽

Vol 116 (suppl_16) ◽

Author(s):

Satoshi Okumura ◽

Yunzhe Bai ◽

Meihua Jin ◽

Sayaka Suzuki ◽

Akiko Kuwae ◽

...

Keyword(s):

Heart Failure ◽

Cyclic Amp ◽

Transgenic Mice ◽

Cardiac Function ◽

Proinflammatory Cytokines ◽

Cardiac Dysfunction ◽

Left Ventricular ◽

Left Ventricular Ejection ◽

Ventricular Ejection Fraction ◽

Stat Pathway

The sympathetic nervous system and proinflammatory cytokines are believed to play independent roles in the pathophysiology of heart failure. However, the recent identification of Epac (exchange protein activated by cyclic AMP), a new cyclic AMP-binding protein that directly activates Rap1, have implicated that there may be a potential cross talk between the sympathetic and cytokine signals. In order to examine the role of Epac in cytokine signal to regulate cardiac function, we have generated transgenic mice expressing the human Epac1 gene under the control of alpha-cardiac myosin heavy chain promoter (Epac1-TG), and examined their response in lipopolysaccharide (LPS)-induced cardiac dysfunction, a well established model for sepsis-induced cardiac dysfunction. Sepsis-induced cardiac dysfunction results from the production of proinflammatory cytokines. At baseline, left ventricular ejection fraction (LVEF) was similar (TG vs. NTG, 67±1.7 vs. 69±2.1%, n =7–9). The degree of cardiac hypertrophy (LV(mg)/tibia(mm)) was also similar at 3 months old (TG vs. NTG 4.0±0.1 vs. 4.2±0.1, n =5–6), but it became slightly but significantly greater in Epac1-TG at 5 month old (TG vs. NTG 4.9±0.1 vs. 4.4±0.1, p< 0.05, n =5–7). LPS (5mg/kg) elicited a significant and robust reduction of LVEF in both Epac1-TG and NTG, but the magnitude of this decrease was much less in Epac1-TG at 6 hr after injection (TG vs. NTG 48±2.4 vs. 57±1.8%, p< 0.01, n =6–9). At 24 hr after injection, cardiac function was restored to the baseline in both Epac1-TG and NTG. We also examined the activation of JAK-STAT pathway at 24 hr after injection. The tyrosine phosphorylation of STAT1 (Tyr701) and STAT3 (Tyr705) in LV, which is an indicator of STAT activation, was reduced to a greater degree in Epac1-TG by 31±8.8% ( p< 0.05, n =4) and 29±5.9% ( p< 0.05, n =7), respectively, relative to that in NTG. Taken together, Epac1 protects the heart from the cytokine-induced cardiac dysfunction, at least in part, through the inhibition of the JAK-STAT pathway, suggesting the beneficial role played by sympathetic signal to antagonize proinflammatory cytokine signal in heart failure.

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