Therapeutic Strategy For Heart Failure Research Articles

Cardio-protective and Antioxidant Potential of Pterocarpus marsupium heartwood extract on Isoproterenol induced heart failure in rats

Heart failure (HF) is a clinical syndrome characterised by a constellation of symptoms(dyspnea, orthopnea, lower limb swelling) and signs (elevated jugular venous pressure, pulmonary congestion) which have underlying cardiac abnormality resulting in reduced cardiac output and/or elevated intra-cardiac pressures. HF is a leading cause of mortality globally and despite major therapeutic advances, HF continues to cause substantial morbidity and mortality. Therefore, there is a need to develop new prophylactic and therapeutic strategies for HF. Isoproterenol (ISO) is a synthetic non-selective beta adrenoceptor agonist and is widely used to model toxic cardiomyopathy and heart failure. It induces myocyte damage mimicking myocardial infarction. In the present study, we used ISO to induce heart failure in Wistar rats and study the effect of Pterocarpus marsupium (PM) heartwood extract on it. PM is a well-recognised herbal drug known for its beneficial effect in diabetes with potential anti-inflammatory and anti-oxidative properties.Hypothesis: PM treatment will favourably modulate the cardiac hemodynamic, anti-oxidative stress and anti-inflammatory parameters compared to standard drug and control rats in isoproterenol induced heart failure rats.Methods & Results. Animals were randomly divided into 10 groups.1: Normal control rats fed normal pellet diet, 2: Normal control rats treated with Fluvastatin (10 mg/kg; oral gavage) for 15 days 3: Normal control rats treated with PM Extract (100 mg/kg; oral gavage) for 15 days. 4: Normal control rats subcutaneously injected with ISO {Heart Failure (HF) group} 5: HF rats treated with Fluvastatin (10 mg/kg; oral gavage) for 15 days. 6: HF rats treated with PM Extract (100 mg/kg; oral gavage) for 15days 7: HF rats treated with PM Extract (200mg/kg; oral gavage) for 15 days. 8: Rats pretreated with Fluvastatin (10 mg/kg; oral gavage) for 15 days and at the 15th day subcutaneously injected with ISO and continued Fluvastatin treatment for another 15 days 9: Rats pretreated with PM Extract (100 mg/kg; oral gavage) for 15 days and at the 15th day subcutaneously injected with ISO and continued PM Extract treatment for another 15 days 10: Rats pretreated with PM Extract (200 mg/kg; oral gavage) for 15 days and at the 15th day subcutaneously injected with ISO and continued PM treatment for another 15 days. The groups were compared pre and post treatment for cardiac hemodynamic parameters, anti- oxidative stress parameters (superoxide dismutase, nitric oxide, malondialdehyde nitric oxide), cardiac injury markers, anti-inflammatory parameters (Interleukin-6 and Tumor Necrosis Factor-α).The results of the present study indicate that prophylactic and therapeutic treatment PM heartwood extract improved the altered hemodynamic and biochemical parameters in isoproterenol-induced HF rats suggesting its cardio-protective action. None declared. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Cardiac Remodeling: Novel Pathophysiological Mechanisms and Therapeutic Strategies.

Morphological and structural remodeling of the heart, including cardiac hypertrophy and fibrosis, has been considered a therapeutic target for heart failure for approximately three decades. Groundbreaking heart failure medications demonstrating reverse remodeling effects have contributed significantly to medical advancements. However, nearly 50% of heart failure patients still exhibit drug resistance, posing a challenge to the healthcare system. Recently, characteristics of heart failure resistant to ARBs and β-blockers have been defined, highlighting preserved systolic function despite impaired diastolic function, leading to the classification of heart failure with preserved ejection fraction (HFpEF). The pathogenesis and etiology of HFpEF may be related to metabolic abnormalities, as evidenced by its mimicry through endothelial dysfunction and excessive intake of high-fat diets. Our recent findings indicate a significant involvement of mitochondrial hyper-fission in the progression of heart failure. This mitochondrial pathological remodeling is associated with redox imbalance, especially hydrogen sulfide accumulation due to abnormal electron leak in myocardium. In this review, we also introduce a novel therapeutic strategy for heart failure from the current perspective of mitochondrial redox-metabolic remodeling.

Beyond Quadruple Therapy and Current Therapeutic Strategies in Heart Failure with Reduced Ejection Fraction: Medical Therapies with Potential to Become Part of the Therapeutic Armamentarium.

Heart failure with reduced ejection fraction (HFrEF) is a complex clinical syndrome with significant morbidity and mortality and seems to be responsible for approximately 50% of heart failure cases and hospitalizations worldwide. First-line treatments of patients with HFrEF, according to the ESC and AHA guidelines, include β-blockers, angiotensin receptor/neprilysin inhibitors, sodium-glucose cotransporter 2 inhibitors, and mineralocorticoid receptor antagonists. This quadruple therapy should be initiated during hospital stay and uptitrated to maximum doses within 6 weeks after discharge according to large multicenter controlled trials. Quadruple therapy improves survival by approximately 8 years for a 55-year-old heart failure patient. Additional therapeutic strategies targeting other signaling pathways such as ivabradine, digoxin, and isosorbide dinitrate and hydralazine combination for African Americans, as well as adjunctive symptomatic therapies, seem to be necessary in the management of HFrEF. Although second-line medications have not achieved improvements in mortality, they seem to decrease heart failure hospitalizations. There are novel medical therapies including vericiguat, omecamtiv mecarbil, genetic and cellular therapies, and mitochondria-targeted therapies. Moreover, mitraclip for significant mitral valve regurgitation, ablation in specific atrial fibrillation cases, omecamtiv mecarbil are options under evaluation in clinical trials. Finally, the HeartMate 3 magnetically levitated centrifugal left ventricular assist device (LVAD) has extended 5-year survival for stage D HF patients who are candidates for an LVAD.

Kielin/chordin-like protein deficiency aggravates pressure overload-induced cardiac dysfunction and remodeling via P53/P21/CCNB1 signaling in mice.

Targeting cardiac remodeling is regarded as a key therapeutic strategy for heart failure. Kielin/chordin-like protein (KCP) is a secretory protein with 18 cysteine-rich domains and associated with kidney and liver fibrosis. However, the relationship between KCP and cardiac remodeling remains unclear. Here, we aimed to investigate the role of KCP in cardiac remodeling induced by pressure overload and explore its potential mechanisms. Left ventricular (LV) KCP expression was measured with real-time quantitative PCR, western blotting, and immunofluorescence staining in pressure overload-induced cardiac remodeling in mice. Cardiac function and remodeling were evaluated in wide-type (WT) mice and KCP knockout (KO) mice by echocardiography, which were further confirmed by histological analysis with hematoxylin and eosin and Masson staining. RNA sequence was performed with LV tissue from WT and KO mice to identify differentially expressed genes and related signaling pathways. Primary cardiac fibroblasts (CFs) were used to validate the regulatory role and potential mechanisms of KCP during fibrosis. KCP was down-regulated in the progression of cardiac remodeling induced by pressure overload, and was mainly expressed in fibroblasts. KCP deficiency significantly aggravated pressure overload-induced cardiac dysfunction and remodeling. RNA sequence revealed that the role of KCP deficiency in cardiac remodeling was associated with cell division, cell cycle, and P53 signaling pathway, while cyclin B1 (CCNB1) was the most significantly up-regulated gene. Further investigation invivo and invitro suggested that KCP deficiency promoted the proliferation of CFs via P53/P21/CCNB1 pathway. Taken together, these results suggested that KCP deficiency aggravates cardiac dysfunction and remodeling induced by pressure overload via P53/P21/CCNB1 signaling in mice.

Integrated miRNA-mRNA networks underlie attenuation of chronic β-adrenergic stimulation-induced cardiac remodeling by minocycline.

Adverse cardiac remodeling contributes to heart failure development and progression, partly due to inappropriate sympathetic nervous system activation. Although β-adrenergic receptor (β-AR) blockade is a common heart failure therapy, not all patients respond, prompting exploration of alternative treatments. Minocycline, an FDA-approved antibiotic, has pleiotropic properties beyond antimicrobial action. Recent evidence suggests it may alter gene expression via changes in miRNA expression. Thus, we hypothesized that minocycline could prevent adverse cardiac remodeling induced by the β-AR agonist isoproterenol, involving miRNA-mRNA transcriptome alterations. Male C57BL/6J mice received isoproterenol (30 mg/kg/day sc) or vehicle via osmotic minipump for 21 days, along with daily minocycline (50 mg/kg ip) or sterile saline. Isoproterenol induced cardiac hypertrophy without altering cardiac function, which minocycline prevented. Total mRNA sequencing revealed isoproterenol altering gene networks associated with inflammation and metabolism, with fibrosis activation predicted by integrated miRNA-mRNA sequencing, involving miR-21, miR-30a, miR-34a, miR-92a, and miR-150, among others. Conversely, the cardiac miRNA-mRNA transcriptome predicted fibrosis inhibition in minocycline-treated mice, involving antifibrotic shifts in Atf3 and Itgb6 gene expression associated with miR-194 upregulation. Picrosirius red staining confirmed isoproterenol-induced cardiac fibrosis, prevented by minocycline. These results demonstrate minocycline's therapeutic potential in attenuating adverse cardiac remodeling through miRNA-mRNA-dependent mechanisms, especially in reducing cardiac fibrosis. NEW & NOTEWORTHY We demonstrate that minocycline treatment prevents cardiac hypertrophy and fibrotic remodeling induced by chronic β-adrenergic stimulation by inducing antifibrotic shifts in the cardiac miRNA-mRNA transcriptome.

Renal denervation improves cardiac function independently of afterload and restores myocardial norepinephrine levels in a rodent heart failure model.

Renal nerves play a critical role in cardiorenal interactions. Renal denervation (RDN) improved survival in some experimental heart failure (HF) models. It is not known whether these favorable effects are indirect, explainable by a decrease in vascular afterload, or diminished neurohumoral response in the kidneys, or whether RDN procedure per se has direct myocardial effects in the failing heart. To elucidate mechanisms how RDN affects failing heart, we studied load-independent indexes of ventricular function, gene markers of myocardial remodeling, and cardiac sympathetic signaling in HF, induced by chronic volume overload (aorto-caval fistula, ACF) of Ren2 transgenic rats. Volume overload by ACF led to left ventricular (LV) hypertrophy and dysfunction, myocardial remodeling (upregulated Nppa, MYH 7/6 genes), increased renal and circulating norepinephrine (NE), reduced myocardial NE content, increased monoaminoxidase A (MAO-A), ROS production and decreased tyrosine hydroxylase (+) nerve staining. RDN in HF animals decreased congestion in the lungs and the liver, improved load-independent cardiac function (Ees, PRSW, Ees/Ea ratio), without affecting arterial elastance or LV pressure, reduced adverse myocardial remodeling (Myh 7/6, collagen I/III ratio), decreased myocardial MAO-A and inhibited renal neprilysin activity. RDN increased myocardial expression of acetylcholinesterase (Ache) and muscarinic receptors (Chrm2), decreased circulating and renal NE, but increased myocardial NE content, restoring so autonomic control of the heart. These changes likely explain improvements in survival after RDN in this model. The results suggest that RDN has remote, load-independent and favorable intrinsic myocardial effects in the failing heart. RDN therefore could be a useful therapeutic strategy in HF.

Shenfu injection improves isoproterenol-induced heart failure in rats by modulating co-metabolism and regulating the trimethylamine-N-oxide - inflammation axis.

Heart failure (HF) is a chronic condition that progressively worsens and continues to be a major financial burden and public health concern. The "gut-heart" axis provides an innovative perspective and therapeutic strategy for preventing and treating heart failure. Shenfu injection (SFI) is a Traditional Chinese Medicine-based treatment demonstrating potential as a therapeutic strategy for heart failure. However, the precise therapeutic mechanisms of SFI in heart failure are not completely characterized. In this study, HF models were established utilizing subcutaneous multipoint injection of isoproterenol (ISO) at a dosage of 5mgkg-1·d-1 for 7days. Serum levels of inflammatory biomarkers were quantified using protein microarrays. Rat feces were analyzed using untargeted metabolomics research and 16S rRNA sequencing. The link between gut microbiota and metabolites was examined using a MetOrigin and Spearman correlation analysis. Our results show that Shenfu injection effectively enhances cardiac function in rats with ISO-induced heart failure by potentially modulating pro-/anti-inflammatory imbalance and reducing serum and urine Trimethylamine-N-oxide (TMAO) levels. Moreover, SFI significantly increases the abundance of Bacteroidota at the phylum level, thereby improving disrupted gut microbiota composition. Additionally, SFI supplementation enriches specific genera known for their capacity to produce short-chain fatty acids. SFI was found to be associated with three key metabolic pathways, as revealed by fecal metabonomics analysis, including the pentose phosphate pathway, pyrimidine metabolism, and purine metabolism. Metabolite tracing analysis revealed that Taurine and hypotaurine metabolism was found to be specific to the microbial community. The biosynthesis of Pyrimidine metabolism, Purine metabolism, beta-alanine metabolism, Naphthalene degradation, Pantothenate, and CoA biosynthesis were identified as co-metabolic pathways between microbes and host. The Spearman correlation analysis was also significantly correlated to differentially expressed metabolites regulated by SFI and the gut microbiota. These results suggest that SFI improves ISO-induced heart failure by modulating co-metabolism and regulating the TMAO-inflammation axis.

Long-Term Maintenance of Normal Serum Vitamin B1 Levels Is Associated with Better Outcomes in Patients with Heart Failure.

Deficiency of vitamin B1 (VB1), an essential micronutrient, causes heart failure (HF). A recent randomized controlled trial failed to show any improvement in HF prognosis after short-term VB1 supplementation. In the current study, we investigated the efficacy of long-term maintenance of normal blood VB1 levels in preventing adverse outcomes in patients with HF.This study included 88 consecutive patients with HF who received guideline-directed medical therapy at Arida Municipal Hospital. The patients were divided into 3 groups: a control group with normal VB1 levels and no VB1 supplementation (normal group, n = 25), and those presenting with VB1 deficiency, who either required short-term VB1 supplementation (short-term supplementation group, n = 25), or long-term maintenance of normal blood VB1 levels (long-term maintenance group, n = 38). The time to the first appearance of composite outcomes, including cardiovascular death and hospitalization for HF, was compared between the 3 groups.VB1 deficiency was observed in 63 (72%) patients. The Kaplan-Meier curve showed that the long-term maintenance group had better outcomes than the other 2 groups. In the multivariate analysis, long-term maintenance of normal blood VB1 levels and age were independent predictors of composite outcomes.VB1 deficiency is frequently observed, and the long-term maintenance of normal blood VB1 levels may result in better outcomes in patients with HF. Our results suggest that the detection of VB1 deficiency and long-term restoration of VB1 levels may be part of the overall therapeutic strategy for HF.

Arginine vasopressin induces ferroptosis to promote heart failure via activation of the V1aR/CaN/NFATC3 pathway.

Arginine vasopressin (AVP) is a key contributor to heart failure (HF), but the underlying mechanisms remain unclear. In the present study, a mouse model of HF and human cardiomyocyte (HCM) cells treated with dDAVP are generated in vivo and in vitro, respectively. Hematoxylin and eosin (HE) staining is used to evaluate the morphological changes in the myocardial tissues. A colorimetric method is used to measure the iron concentration, Fe 2+ concentration and malondialdehyde (MDA) level. Western blot analysis is used to examine the protein levels of the V1a receptor (V1aR), calcineurin (CaN), nuclear factor of activated T cells isoform C3 (NFATC3), glutathione peroxidase 4 (GPX4) and acyl-CoA synthase long chain family member 4 (ACSL4). Immunoprecipitation (IP) and luciferase reporter assays are performed to determine the interaction between NFATC3 and ACSL4. Both in vivo and in vitro experiments reveal that the V1aR-CaN-NFATC3 signaling pathway and ferroptosis are upregulated in HFs, which are verified by the elevated protein levels of V1aR, CaN, NFATC3 and ACSL4; reduced GPX4 protein level; and enhanced Fe 2+ and MDA levels. We further find that inhibiting NFATC3 by suppressing the V1aR/CaN/NFATC3 pathway via V1aR/CaN inhibitors or sh-NFATC3 not only alleviates HF but also inhibits AVP-induced ferroptosis. Mechanistically, sh-NFATC3 significantly reverses the increase in AVP-induced ACSL4 protein level, Fe 2+ concentration, and MDA level by directly interacting with ACSL4. Our results demonstrate that AVP enhances ACSL4 expression by activating the V1aR/CaN/NFATC3 pathway to induce ferroptosis, thus contributing to HF. This study may lead to the proposal of a novel therapeutic strategy for HF.

Identification and exploration of aging-related subtypes and distinctive role of SERPINE1 in heart failure based on single-cell and bulk RNA sequencing data.

Aging is a major risk factor for heart failure (HF) and is the leading cause of death worldwide. Currently, the nature of the relationship between aging and HF is not entirely clear. Herein, this study aimed to explore new diagnostic biomarkers, molecular typing and therapeutic strategies for HF by investigating the biological significance of aging-related genes in HF. A total of 157 differentially expressed genes (DEGs) were screened totally between HF and normal samples, and functional enrichment analysis of DEGs revealed the strong association of HF progression with aging, immune processes and metabolism. Six HF-specific aging-related genes were further identified, and a diagnostic model was developed and validated for good diagnostic efficacy. In addition, we collected blood samples from 10 normal controls and 10 HF patients for RT-qPCR analysis to verify the bioinformation. We also identified two aging-associated subtypes with distinctly different immune infiltration and metabolic microenvironment. Further single-cell sequencing analysis conducted in the study identified SERPINE1 as a key gene in HF. The distinctive role of SERPINE1 fibroblasts was revealed, including three main findings: (I) fibroblasts had a higher proportion and expression of SERPINE1 levels in HF; (II) the ligand-receptor pair MDK-LRP1 made the most contributions in high interactions with other cell types in SERPINE1 fibroblasts; and (III) SERPINE1 fibroblasts were associated with the interaction of extracellular matrix and receptor and may be regulated by the transcription factor EGR1. In conclusion, this study highlights the importance of aging-related genes in diagnosing HF and regulating immune infiltration. We also identified different HF subtypes and a potentially crucial gene, which may provide a better understanding of the molecular-level mechanisms of aging-related HF and aid in developing effective therapeutic strategies.

Combined Inhibition of Phosphodiesterase-5 and -9 in Experimental Heart Failure

BackgroundIntracellular second messenger cyclic guanosine monophosphate (cGMP) mediates bioactivity of the natriuretic peptides and nitric oxide, and is key to circulatory homeostasis and protection against cardiovascular disease. Inhibition of cGMP-degrading phosphodiesterases (PDEs) PDE5 and PDE9 are emerging as pharmacological targets in heart failure (HF). ObjectivesThe present study investigated dual enhancement of cGMP in experimental HF by combining inhibition of PDE-5 (P5-I) and PDE-9 (P9-I). MethodsEight sheep with pacing-induced HF received on separate days intravenous P5-I (sildenafil), P9-I (PF-04749982), P5-I+P9-I, and vehicle control, in counterbalanced order. ResultsCompared with control, separate P5-I and P9-I significantly increased circulating cGMP concentrations in association with reductions in mean arterial pressure (MAP), left atrial pressure (LAP), and pulmonary arterial pressure (PAP), with effects of P5-I on cGMP, MAP, and PAP greater than those of P9-I. Only P5-I decreased pulmonary vascular resistance. Combination P5-I+P9-I further reduced MAP, LAP, and PAP relative to inhibition of either phosphodiesterase alone. P9-I and, especially, P5-I elevated urinary cGMP levels relative to control. However, whereas inhibition of either enzyme increased urine creatinine excretion and clearance, only P9-I induced a significant diuresis and natriuresis. Combined P5-I+P9-I further elevated urine cGMP with concomitant increases in urine volume, sodium and creatinine excretion, and clearance similar to P9-I alone, despite the greater MAP reductions induced by combination treatment. ConclusionsCombined P5-I+P9-I amalgamated the superior renal effects of P9-I and pulmonary effects of P5-1, while concurrently further reducing cardiac preload and afterload. These findings support combination P5-I+P9-I as a therapeutic strategy in HF.

Novel Therapeutic Strategies in Heart Failure in Adult Congenital Heart Disease: of Medicines and Devices.

This paper reviews the latest literature on the growing field of heart failure in the adult congenital heart disease population. After highlighting the increasing prevalence and a few of the unique potential causes, including the concept of early senescence, this review begins with novel medical management strategies such as the angiotensin II receptor blocker and neprilysin inhibitors and sodium glucose cotransporter-2 inhibitors. Then, it addresses the latest applications of percutaneous techniques like implantable hemodynamic monitoring, transcatheter pulmonary and aortic valve replacement, and mitral clips. Cardiac resynchronization therapy and novel lymphatic system imaging and intervention are then described. Finally, the use of mechanical support devices, temporary and durable, is discussed as well as heart and combined heart and liver transplantation. There have been recent exciting advances in the strategies used to manage adult congenital heart disease patients with heart failure. As this population continues to grow, it is likely we will see further rapid evolution in this field.

Targeting epicardial adipose tissue: A potential therapeutic strategy for heart failure with preserved ejection fraction with type 2 diabetes mellitus.

Heart failure with preserved ejection fraction (HFpEF) is a heterogeneous syndrome with various comorbidities, multiple cardiac and extracardiac pathophysiologic abnormalities, and diverse phenotypic presentations. Since HFpEF is a heterogeneous disease with different phenotypes, individualized treatment is required. HFpEF with type 2 diabetes mellitus (T2DM) represents a specific phenotype of HFpEF, with about 45%-50% of HFpEF patients suffering from T2DM. Systemic inflammation associated with dysregulated glucose metabolism is a critical pathological mechanism of HFpEF with T2DM, which is intimately related to the expansion and dysfunction (inflammation and hypermetabolic activity) of epicardial adipose tissue (EAT). EAT is well established as a very active endocrine organ that can regulate the pathophysiological processes of HFpEF with T2DM through the paracrine and endocrine mechanisms. Therefore, suppressing abnormal EAT expansion may be a promising therapeutic strategy for HFpEF with T2DM. Although there is no treatment specifically for EAT, lifestyle management, bariatric surgery, and some pharmaceutical interventions (anti-cytokine drugs, statins, proprotein convertase subtilisin/kexin type 9 inhibitors, metformin, glucagon-like peptide-1 receptor agonists, and especially sodium-glucose cotransporter-2 inhibitors) have been shown to attenuate the inflammatory response or expansion of EAT. Importantly, these treatments may be beneficial in improving the clinical symptoms or prognosis of patients with HFpEF. Accordingly, well-designed randomized controlled trials are needed to validate the efficacy of current therapies. In addition, more novel and effective therapies targeting EAT are needed in the future.

HIPK1 Inhibition Protects against Pathological Cardiac Hypertrophy by Inhibiting the CREB-C/EBPβ Axis.

Inhibition of pathological cardiac hypertrophy is recognized as an important therapeutic strategy for heart failure, although effective targets are still lacking in clinical practice. Homeodomain interacting protein kinase 1 (HIPK1) is a conserved serine/threonine kinase that can respond to different stress signals, however, whether and how HIPK1 regulates myocardial function is not reported. Here, it is observed that HIPK1 is increased during pathological cardiac hypertrophy. Both genetic ablation and gene therapy targeting HIPK1 are protective against pathological hypertrophy and heart failure in vivo. Hypertrophic stress-induced HIPK1 is present in the nucleus of cardiomyocytes, while HIPK1 inhibition prevents phenylephrine-induced cardiomyocyte hypertrophy through inhibiting cAMP-response element binding protein (CREB) phosphorylation at Ser271 and inactivating CCAAT/enhancer-binding protein β (C/EBPβ)-mediated transcription of pathological response genes. Inhibition of HIPK1 and CREB forms a synergistic pathway in preventing pathological cardiac hypertrophy. In conclusion, HIPK1 inhibition may serve as a promising novel therapeutic strategy to attenuate pathological cardiac hypertrophy and heart failure.

Integrated proteomics reveals alterations in sarcomere composition and developmental processes during postnatal swine heart development

The neonatal swine heart possesses an endogenous ability to regenerate injured myocardium through the proliferation of pre-existing cardiomyocyte (CM) populations. However, this regenerative capacity is lost shortly after birth. Normal postnatal developmental processes and the regenerative capacity of mammalian hearts are tightly linked, but not much is known about how the swine cardiac proteome changes throughout postnatal development. Herein, we integrated robust and quantitative targeted “top-down” and global “bottom-up” proteomic workflows to comprehensively define the dynamic landscape of the swine cardiac proteome throughout postnatal maturation. Using targeted top-down proteomics, we were able to identify significant alterations in sarcomere composition, providing new insight into the proteoform landscape of sarcomeres that can disassemble, a process necessary for productive CM proliferation. Furthermore, we quantified global changes in protein abundance using bottom-up proteomics, identified over 700 differentially expressed proteins throughout postnatal development, and mapped these proteins to changes in developmental and metabolic processes. We envision these results will help guide future investigations to comprehensively understand endogenous cardiac regeneration toward the development of novel therapeutic strategies for heart failure.

LonP1 Links Mitochondria-ER Interaction to Regulate Heart Function.

Interorganelle contacts and communications are increasingly recognized to play a vital role in cellular function and homeostasis. In particular, the mitochondria-endoplasmic reticulum (ER) membrane contact site (MAM) is known to regulate ion and lipid transfer, as well as signaling and organelle dynamics. However, the regulatory mechanisms of MAM formation and their function are still elusive. Here, we identify mitochondrial Lon protease (LonP1), a highly conserved mitochondrial matrix protease, as a new MAM tethering protein. The removal of LonP1 substantially reduces MAM formation and causes mitochondrial fragmentation. Furthermore, deletion of LonP1 in the cardiomyocytes of mouse heart impairs MAM integrity and mitochondrial fusion and activates the unfolded protein response within the ER (UPRER). Consequently, cardiac-specific LonP1 deficiency causes aberrant metabolic reprogramming and pathological heart remodeling. These findings demonstrate that LonP1 is a novel MAM-localized protein orchestrating MAM integrity, mitochondrial dynamics, and UPRER, offering exciting new insights into the potential therapeutic strategy for heart failure.

Mechanisms of current therapeutic strategies for heart failure: more questions than answers?

Heart failure (HF) is a complex, multifactorial and heterogeneous syndrome with substantial mortality and morbidity. Over the last few decades, numerous attempts have been made to develop targeted therapies which may attenuate the known pathophysiological pathways responsible for causing progression of HF. However, therapies developed with this objective have sometimes failed to show benefit. The pathophysiological construct of HF with numerous etiologies suggests that interventions with broad mechanisms of action which simultaneously target more than one pathway maybe more effective in improving outcomes of patients with HF. Indeed, current therapeutics with clinical benefit in HF have targeted a wider range of intermediate phenotypes. Despite extensive scientific breakthroughs in HF research recently, questions persist regarding the ideal therapeutic targets which may help achieve maximum benefit. In this review, we evaluate the mechanism of action of current therapeutic strategies, the pathophysiological pathways they target and highlight remaining knowledge gaps regarding the mode of action of these interventions.

Abstract 10039: Cardiomyocyte N-myristoylation Plays an Essential Role During the Development of Heart Failure

Background: N-myristoylation is co- and post-translational modifications of proteins, which involve attachment of myristic acid to the N-terminal glycine. Although N-myristoylation plays important roles in physiological activities such as intracellular signaling, the precise regulation and functional relevance of N-myristoylation in the heart remain to be elucidated. Methods and Results: We applied a click chemistry-based approach to determine the global N-myristoylated protein profiling in the cardiomyocyte. Proteomics analysis identified 41 and 34 N-myristoylated proteins in H9c2 myocytes and neonatal rat cardiomyocytes, and 66.1% of them were discovered for the first time at endogenous levels. The levels of N-myristoylation were significantly decreased by the N-myristoyltransferase (NMT) 2 inhibition with siRNA or adenoviral shRNA knockdown, but not by the NMT1 inhibition. In response to angiotensin II (AII), N-myristoylated levels were differentially altered, and MARCKS was identified as the most down-regulated N-myristoylated protein. Wild-type MARCKS was localized to the cellular membrane, while the mutant MARKS with replacement of N-terminal glycine to alanine (G2A), which lacked the capacity of N-myristoylation, exhibited cytosolic distribution. Cardiomyocyte hypertrophy was exacerbated in mutant G2A MARCKS accompanied by increased levels of histone acetylation and phosphorylation of HDAC4 and CaMKII after AII. Gene transfer delivering NMT2 gene specific to the heart using adeno-associated virus 9 significantly improved pressure overload-induced left ventricular systolic dysfunction, cardiac hypertrophy, and myocardial fibrosis, associated with decreased levels of histone acetylation after the transverse aortic constriction in mice ( Fig ). Conclusion: Cardiomyocyte N-myristoylation plays an essential role in developing heart failure, and its modification by NMT2 may be a novel therapeutic strategy for heart failure.

Immunomodulatory Cell Therapy Using αGalCer-Pulsed Dendritic Cells Ameliorates Heart Failure in a Murine Dilated Cardiomyopathy Model.

Dilated cardiomyopathy (DCM) is a life-threatening disease, resulting in refractory heart failure. An immune disorder underlies the pathophysiology associated with heart failure progression. Invariant natural killer T (iNKT) cell activation is a prospective therapeutic strategy for ischemic heart disease. However, its efficacy in nonischemic cardiomyopathy, such as DCM, remains to be elucidated, and the feasible modality for iNKT cell activation in humans is yet to be validated. Dendritic cells isolated from human volunteers were pulsed with α-galactosylceramide ex vivo, which were used as α-galactosylceramide-pulsed dendritic cells (αGCDCs). We treated DCM mice harboring mutated troponin TΔK210/ΔK210 with αGCDCs and evaluated the efficacy of iNKT cell activation on heart failure in DCM mice. Furthermore, we investigated the molecular basis underlying its therapeutic effects in these mice and analyzed primary cardiac cells under iNKT cell-secreted cytokines. The number of iNKT cells in the spleens of DCM mice was reduced compared with that in wild-type mice, whereas αGCDC treatment activated iNKT cells, prolonged survival of DCM mice, and prevented decline in the left ventricular ejection fraction for 4 weeks, accompanied by suppressed interstitial fibrosis. Mechanistically, αGCDC treatment suppressed TGF (transforming growth factor)-β signaling and expression of fibrotic genes and restored vasculature that was impaired in DCM hearts by upregulating angiopoietin 1 (Angpt1) expression. Consistently, IFNγ (interferon gamma) suppressed TGF-β-induced Smad2/3 signaling and the expression of fibrotic genes in cardiac fibroblasts and upregulated Angpt1 expression in cardiomyocytes via Stat1. Immunomodulatory cell therapy with αGCDCs is a novel therapeutic strategy for heart failure in DCM.

Effects of resistance exercise in the cardiac remodeling of myocardial infarction rats

Abstract Introduction Exercise is an important therapeutic strategy for heart failure (HF). However, the myocardial effects of resistance exercise during HF are not completely understood. In this study, we investigated the influence of resistance exercise on cardiac remodeling and molecular myocardial changes of rats with myocardial infarction (MI)-induced HF. Methods Three months after MI induction or simulated surgery, Wistar rats were divided into three groups: Sham (n=14); MI (n=9); and MI subjected to resistance exercise (MI-R, n=13). Exercised rats trained 3 times a week during 12 weeks performing four climbs in a ladder with progressive loads. Cardiac structure and left ventricular function were assessed by echocardiogram. Myocyte diameters were measured in histological sections. Energy metabolism, lipid hydroperoxide, antioxidant enzymes activity, malondialdehyde, and protein carbonylation were evaluated by spectrophotometry. NADPH oxidase subunits (Nox2, Nox4, p22phox and p47phox) gene expression was assessed by RT-PCR. Statistical analysis: ANOVA and Tukey test or Dunn's test. Results Mortality did not differ between MI-R and MI groups. MI-R and MI presented dilated left atrium and left ventricle with systolic and diastolic dysfunction. Exercise improved maximum carrying load with no changes in cardiac structure or left ventricle function. Myocyte diameter was lower in MI than Sham and MI-R. Lactate dehydrogenase and creatine kinase activities were lower in MI than Sham. Activity of citrate synthase and catalase was lower in MI and MI-R than Sham. Lipid hydroperoxide concentration was lower in MI-R than MI. Nox2 and p22phox gene expression was higher in MI-R than Sham. Gene expression of Nox4 was higher in both infarcted groups and gene expression of p47phox was lower in MI than Sham. Conclusion Resistance exercise is safe and well tolerated by infarcted rats. Exercise increases maximum carrying load and reduces myocardial oxidative stress with no changes in cardiac structure or left ventricle function of infarcted rats. Funding Acknowledgement Type of funding sources: Public Institution(s). Main funding source(s): CNPq - National Council for Scientific and Technological Development