Animal Models Of Heart Failure Research Articles

Renal denervation: a key approach to hypertension and cardiovascular disease.

Sympathetic activation plays a critical role in the development of hypertension and cardiovascular disease, including heart failure and arrhythmias. Renal nerves contribute to the regulation of blood pressure and fluid volume through renal sympathetic efferent nerves, and to the modulation of sympathetic outflow through renal sensory afferent nerves. Previous studies including ours suggest that selective afferent renal denervation with preservation of efferent renal nerves can significantly decrease central sympathetic outflow in animal models of hypertension with renal damage. In Dahl salt-sensitive rats fed high salt diet from an early age, a model of hypertensive heart failure, this central sympathoinhibition by afferent renal denervation may attenuate the development of heart failure without significant blood pressure reduction. Accumulating clinical evidence supports the efficacy of renal denervation as an antihypertensive treatment. However, it remains important to clarify the appropriate indications and predictors of responders to renal denervation in the treatment of hypertension. Several clinical studies suggest beneficial effects of renal denervation in patients with heart disease, with or without hypertension, although most were not sham-controlled. In particular, some clinical studies have demonstrated that renal denervation reduces the incidence of atrial fibrillation or cardiovascular events even without a significant antihypertensive effect. It is essential to accumulate more insightful data in patients undergoing renal denervation, to establish the efficacy of renal denervation in patients with cardiovascular disease in the clinical setting, and to elucidate the therapeutic mechanisms of renal denervation and the renal nerves-linked pathophysiology of cardiovascular disease in basic research. This review outlines the effects of renal denervation on sympathetic activity and organ damage in animal models of hypertension and hypertensive heart failure, including our own data. Beyond the antihypertensive effects, the beneficial effects of renal denervation on cardiovascular disease are also discussed based on clinical studies. Several animal and clinical studies suggest the cardioprotective effects of renal denervation even in the absence of significant blood pressure reduction, probably due to its sympathoinhibitory effects.

Proteomics couples electrical remodelling to inflammation in a murine model of heart failure with sinus node dysfunction.

In patients with heart failure (HF), concomitant sinus node dysfunction (SND) is an important predictor of mortality, yet its molecular underpinnings are poorly understood. Using proteomics, this study aimed to dissect the protein and phosphorylation remodelling within the sinus node in an animal model of HF with concurrent SND. We acquired deep sinus node proteomes and phosphoproteomes in mice with heart failure and SND and report extensive remodelling. Intersecting the measured (phospho)proteome changes with human genomics pharmacovigilance data, highlighted downregulated proteins involved in electrical activity such as the pacemaker ion channel, Hcn4. We confirmed the importance of ion channel downregulation for sinus node physiology using computer modelling. Guided by the proteomics data, we hypothesized that an inflammatory response may drive the electrophysiological remodeling underlying SND in heart failure. In support of this, experimentally induced inflammation downregulated Hcn4 and slowed pacemaking in the isolated sinus node. From the proteomics data we identified proinflammatory cytokine-like protein galectin-3 as a potential target to mitigate the effect. Indeed, in vivo suppression of galectin-3 in the animal model of heart failure prevented SND. Collectively, we outline the protein and phosphorylation remodeling of SND in heart failure, we highlight a role for inflammation in electrophysiological remodelling of the sinus node, and we present galectin-3 signalling as a target to ameliorate SND in heart failure.

Preload dependence in an animal model of mild heart failure with preserved ejection fraction (HFpEF).

Heart Failure with preserved Ejection Fraction (HFpEF) is characterized by diastolic dysfunction and reduced cardiac output, but its pathophysiology remains poorly understood. Animal models of HFpEF are challenging due to difficulties in assessing the degree of heart failure in small animals. This study aimed at inducing HFpEF in a mouse model to probe preload-dependency. Increased body mass and arterial hypertension were induced in mice using a Western diet and NO synthase inhibition. Preload dependence was tested exvivo. Mice with obesity and hypertension exhibited reduced cardiac output, indicating a failing heart. Increased left ventricular filling pressure during diastole suggested reduced compliance. Notably, the ejection fraction was preserved, suggesting the development of HFpEF. Spontaneous physical activity at night was reduced in HFpEF mice, indicating exercise intolerance; however, the cardiac connective tissue content was comparable between HFpEF and control mice. The HFpEF mice showed increased vulnerability to reduced preload exvivo, indicating that elevated left ventricular filling pressure compensated for the rigid left ventricle, preventing a critical decrease in cardiac output. This animal model successfully developed mild HFpEF with a reduced pump function that was dependent on a high preload. A model of mild HFpEF may serve as a valuable tool for studying disease progression and interventions aimed at delaying or reversing symptom advancement, considering the slow development of HFpEF in patients.

Evaluation of Tyrosine Kinase Inhibitors Loaded Injectable Hydrogels for Improving Connexin43 Gap Junction Intercellular Communication.

Myocardial infarction (MI) is one of the leading causes of death in the developed world, and the loss of cardiomyocytes plays a critical role in the pathogenesis of heart failure. Implicated in this process is a decrease in gap junction intercellular communication due to remodeling of Connexin43 (Cx43). We previously identified that intraperitoneal injection of the Pyk2 inhibitor PF4618433 reduced infarct size, maintained Cx43 at the intercalated disc in left ventricle hypertrophic myocytes, and improved cardiac function in an MI animal model of heart failure. With the emergence of injectable hydrogels as a therapeutic toward the regeneration of cardiac tissue after MI, here, we provide proof of concept that the release of tyrosine kinase inhibitors from hydrogels could have beneficial effects on cardiomyocytes. We developed an injectable hydrogel consisting of thiolated hyaluronic acid and P123-maleimide micelles that can incorporate PF4618433 as well as the Src inhibitor Saracatinib and achieved sustained release (of note, Src activates Pyk2). Using neonatal rat ventricular myocytes in the presence of a phorbol ester, endothelin-1, or phenylephrine to stimulate cardiac hypertrophy, the release of PF4618433 from the hydrogel had the same ability to decrease Cx43 tyrosine phosphorylation and maintain Cx43 localization at the plasma membrane as when directly added to the growth media. Additional beneficial effects included decreases in apoptosis, the hypertrophic marker atrial natriuretic peptide (ANP), and serine kinases upregulated in hypertrophy. Finally, the presence of both PF4618433 and Saracatinib further decreased the level of ANP and apoptosis than each inhibitor alone, suggesting that a combinatorial approach may be most beneficial. These findings provide the groundwork to test if tyrosine kinase inhibitor release from hydrogels will have a beneficial effect in an animal model of MI-induced heart failure.

Preclinical Proof-of-Concept of a Minimally Invasive Direct Cardiac Compression Device for Pediatric Heart Support

PurposeFor pediatric patients, extracorporeal membrane oxygenation (ECMO) remains the predominant mechanical circulatory support (MCS) modality for heart failure (HF) although survival to discharge rates remain between 50 and 60% for these patients. The device-blood interface and disruption of physiologic hemodynamics are significant contributors to poor outcomes.MethodsIn this study, we evaluate the preclinical feasibility of a minimally invasive, non-blood-contacting pediatric DCC prototype for temporary MCS. Proof-of-concept is demonstrated in vivo in an animal model of HF. Hemodynamic pressures and flows were examined.ResultsMinimally invasive deployment on the beating heart was successful without cardiopulmonary bypass or anticoagulation. During HF, device operation resulted in an immediate 43% increase in cardiac output while maintaining pulsatile hemodynamics. Compared to the pre-HF baseline, the device recovered up to 95% of ventricular stroke volume. At the conclusion of the study, the device was easily removed from the beating heart.ConclusionsThis preclinical proof-of-concept study demonstrated the feasibility of a DCC device on a pediatric scale that is minimally invasive and non-blood contacting, with promising hemodynamic support and durability for the initial intended duration of use. The ability of DCC to maintain pulsatile MCS without blood contact represents an opportunity to mitigate the mortality and morbidity observed in non-pulsatile, blood-contacting MCS.

Abstract 18258: Leucine Supplementation Improves Myocardial Function in a HFpEF Rat Model

Introduction: We previously documented that leucine supplementation protects from skeletal muscle atrophy by increasing skeletal muscle mass and force during hind limb immobilization. One of the proposed underlying mechanisms was the suppression of HDAC4 protein expression and increased nuclei accretion. Hypothesis: The present study aimed to examine whether the protective effects of leucine supplementation are also observed in the myocardium in an animal model of heart failure with preserved ejection fraction (HFpEF) and to assess the role of HDAC4 modulation. Methods: Female ZSF1 lean (control, con) and obese (HFpEF) rats were randomized at an age of 20 weeks to one of three groups: lean rats receiving standard chow (con), obese rats receiving standard chow (HFpEF), and obese rats receiving leucine-supplemented chow (3% w/w) for 12 weeks (HFpEF/leu). All animals underwent echocardiography at baseline and after 6 and 12 weeks. Prior to organ harvest left ventricular (LV) hemodynamics were measured invasively, blood samples were taken, cardiac mitochondrial function was assessed and LV tissue was collected for molecular and histological analyses. Results: Assessment of diastolic function revealed a 20% reduction of E/é in the HFpEF/leu group compared to untreated HFpEF. While no alterations of left ventricular hemodynamics were observed between the groups, stiffness factor β was significantly reduced in leucine-treated rats. Left ventricular mRNA levels of Collagen type I a1 and matrix metalloproteinase 2 were reduced by 25% and 22%, respectively. Assessment of mitochondrial oxidative phosphorylation revealed a significant improvement of complex-I- and complex-II mediated respiration in leucine-treated rats compared to HFpEF. Finally, HDAC4 protein expression levels were reduced by 40% in the HFpEF/leu group compared to HFpEF. Conclusions: This study presents beneficial effects of leucine supplementation on cardiac function, remodeling, and metabolic parameters in an HFpEF rat model. These benefits may be attributed to suppressed HDAC4 expression.

Abstract 15137: microRNA-132 Inhibition Improves Cardiac Function and Reduces Remodeling in Patients With Heart Failure With Reduced Ejection Fraction (HFrEF): An Exploratory Subgroup Analysis of the CDR132L First-in-Human Study

Background: The CDR132L first-in-human (FiH) study examined safety, tolerability, pharmacokinetic, and exploratory pharmacodynamic effects of different ascending doses of the novel antisense oligonucleotide CDR132L targeting microRNA-132-3p (miR-132) in patients with stable heart failure (HF) of ischemic origin receiving standard-of-care (n=28). The study population was not stratified according to their left-ventricular ejection fraction (LVEF), and therefore heterogenous, but equally distributed among heart failure with reduced or preserved ejection fraction (HFrEF or HFpEF). Research question: In an exploratory post-hoc analysis of pharmacodynamic parameters we specifically focused on patients with HFrEF (with a LVEF<45% at baseline, n=14) and, based on our predictive PK/PD modeling, categorized patients into ‘non-pharmacodynamically active’ (non-PD active; placebo and 0.32 mg/kg CDR132L group) and 'pharmacodynamically active' (PD active; patients receiving 1, 3, or 10 mg/kg CDR132L). Results: The PD active group showed a significant median reduction in NT-proBNP by 37.1% between baseline and study endpoint (day 112) while this HF biomarker was increased by 17.7% in the non-PD active group (p=0.0152, Mann-Whitney U test). CDR132L treatment provoked a trend towards 6.1% improvement in LVEF. For the non-PD active group only +1.4% were noted. An additional biomarker related to HF and cardiac fibrosis, lipocalin-2 (NGAL), tended to decrease in the PD active, but not in the non-PD active group. Conclusion: Analysis of the HFrEF subgroup in this FiH trial, although limited by the small patient numbers, indicatively underlines the encouraging benefits of CDR132L, a novel antisense drug, on LV function and cardiac remodeling as established in previous large animal HF models.

Leucine Supplementation Improves Diastolic Function in HFpEF by HDAC4 Inhibition.

Heart failure with preserved ejection fraction (HFpEF) is a complex syndrome associated with a high morbidity and mortality rate. Leucine supplementation has been demonstrated to attenuate cardiac dysfunction in animal models of cachexia and heart failure with reduced ejection fraction (HFrEF). So far, no data exist on leucine supplementation on cardiac function in HFpEF. Thus, the current study aimed to investigate the effect of leucine supplementation on myocardial function and key signaling pathways in an established HFpEF rat model. Female ZSF1 rats were randomized into three groups: Control (untreated lean rats), HFpEF (untreated obese rats), and HFpEF_Leu (obese rats receiving standard chow enriched with 3% leucine). Leucine supplementation started at 20 weeks of age after an established HFpEF was confirmed in obese rats. In all animals, cardiac function was assessed by echocardiography at baseline and throughout the experiment. At the age of 32 weeks, hemodynamics were measured invasively, and myocardial tissue was collected for assessment of mitochondrial function and for histological and molecular analyses. Leucine had already improved diastolic function after 4 weeks of treatment. This was accompanied by improved hemodynamics and reduced stiffness, as well as by reduced left ventricular fibrosis and hypertrophy. Cardiac mitochondrial respiratory function was improved by leucine without alteration of the cardiac mitochondrial content. Lastly, leucine supplementation suppressed the expression and nuclear localization of HDAC4 and was associated with Protein kinase A activation. Our data show that leucine supplementation improves diastolic function and decreases remodeling processes in a rat model of HFpEF. Beneficial effects were associated with HDAC4/TGF-β1/Collagenase downregulation and indicate a potential use in the treatment of HFpEF.

RUNX1 facilitates heart failure progression through regulating TGF-β-induced cardiac remodeling.

Heart failure is caused by acute or chronic cardiovascular diseases with limited treatments and unclear pathogenesis. Therefore, it is urgent to explore new therapeutic targets and reveal new pathogenesis for heart failure. We carried out heart failure animal model by transverse aortic arch constriction (TAC) in mice. The left ventricular internal diameter diastole (LVIDd), left ventricular internal diameter systole (LVIDs), and ejection fraction (EF) value were detected using ultrasound and myocardial fibrosis was evaluated by Masson stain assay. Cell apoptosis in myocardial tissues were detected by TUNEL immunofluorescence stain. Signal pathway analysis was performed by dual-luciferase reporter assay and western blot. Our results showed that inhibition of RUNX1 led to remission of cardiac enlargement induced by TAC in mice. Inhibition of RUNX1 also caused raise of EF and FS value under TAC-induced condition. Besides, RUNX1 inhibition mice showed decreased myocardial fibrosis area under TAC-induced condition. RUNX1 inhibition caused decrease of apoptotic cell rate in myocardial tissues under TAC. Interestingly, we found that RUNX1 could promote the activation of TGF-β/Smads in dual-luciferase reporter assay. We illustrated that RUNX1 could be considered as a new regulator of myocardial remodeling by activating TGF-β/Smads signaling. Based on this, we concluded that RUNX1 may be developed as a new therapeutic target against heart failure in the future. In addition, this study also provide a new insight for the etiological study on heart failure.

The effect of zofenopril on the cardiovascular system of spontaneously hypertensive rats treated with the ACE2 inhibitor MLN-4760

BackgroundAngiotensin converting enzyme 2 (ACE2) plays a crucial role in the infection cycle of SARS-CoV-2 responsible for formation of COVID-19 pandemic. In the cardiovascular system, the virus enters the cells by binding to the transmembrane form of ACE2 causing detrimental effects especially in individuals with developed hypertension or heart disease. Zofenopril, a H2S-releasing angiotensin-converting enzyme inhibitor (ACEI), has been shown to be effective in the treatment of patients with essential hypertension; however, in conditions of ACE2 inhibition its potential beneficial effect has not been investigated yet. Therefore, the aim of the study was to determine the effect of zofenopril on the cardiovascular system of spontaneously hypertensive rats, an animal model of human essential hypertension and heart failure, under conditions of ACE2 inhibition induced by the administration of the specific inhibitor MLN-4760 (MLN).ResultsZofenopril reduced MLN-increased visceral fat to body weight ratio although no changes in systolic blood pressure were recorded. Zofenopril administration resulted in a favorable increase in left ventricle ejection fraction and improvement of diastolic function regardless of ACE2 inhibition, which was associated with increased H2S levels in plasma and heart tissue. Similarly, the acute hypotensive responses induced by acetylcholine, L-NAME (NOsynthase inhibitor) and captopril (ACEI) were comparable after zofenopril administration independently from ACE2 inhibition. Although simultaneous treatment with zofenopril and MLN led to increased thoracic aorta vasorelaxation, zofenopril increased the NO component equally regardless of MLN treatment, which was associated with increased NO-synthase activity in aorta and left ventricle. Moreover, unlike in control rats, the endogenous H2S participated in maintaining of aortic endothelial function in MLN-treated rats and the treatment with zofenopril had no impact on this effect.ConclusionsZofenopril treatment reduced MLN-induced adiposity and improved cardiac function regardless of ACE2 inhibition. Although the concomitant MLN and zofenopril treatment increased thoracic aorta vasorelaxation capacity, zofenopril increased the participation of H2S and NO in the maintenance of endothelial function independently from ACE2 inhibition. Our results confirmed that the beneficial effects of zofenopril were not affected by ACE2 inhibition, moreover, we assume that ACE2 inhibition itself can lead to the activation of cardiovascular compensatory mechanisms associated with Mas receptor, nitrous and sulfide signaling.

Animal models of heart failure with preserved ejection fraction (HFpEF): from metabolic pathobiology to drug discovery.

Heart failure (HF) with preserved ejection fraction (HFpEF) is currently a preeminent challenge for cardiovascular medicine. It has a poor prognosis, increasing mortality, and is escalating in prevalence worldwide. Despite accounting for over 50% of all HF patients, the mechanistic underpinnings driving HFpEF are poorly understood, thus impeding the discovery and development of mechanism-based therapies. HFpEF is a disease syndrome driven by diverse comorbidities, including hypertension, diabetes and obesity, pulmonary hypertension, aging, and atrial fibrillation. There is a lack of high-fidelity animal models that faithfully recapitulate the HFpEF phenotype, owing primarily to the disease heterogeneity, which has hampered our understanding of the complex pathophysiology of HFpEF. This review provides an updated overview of the currently available animal models of HFpEF and discusses their characteristics from the perspective of energy metabolism. Interventional strategies for efficiently utilizing energy substrates in preclinical HFpEF models are also discussed.

Imaging characterization of myocardial function, fibrosis, and perfusion in a nonhuman primate model with heart failure-like features.

The availability of a human-like chronic heart failure (HF) animal model was critical for affiliating development of novel therapeutic drug treatments. With the close physiology relatedness to humans, the non-human primate (NHP) HF model would be valuable to better understand the pathophysiology and pharmacology of HF. The purpose of this work was to present preliminary cardiac image findings using echocardiography and cardiovascular magnetic resonance (CMR) in a HF-like cynomolgus macaque model. The NHP diet-induced model developed cardiac phenotypes that exhibited diastolic dysfunction with reduced left ventricular ejection fraction (LVEF) or preserved LVEF. Twenty cynomolgus monkeys with cardiac dysfunction were selected by echocardiography and subsequently separated into two groups, LVEF < 65% (termed as HFrEF, n = 10) and LVEF ≥ 65% with diastolic dysfunction (termed as HFpEF, n = 10). Another group of ten healthy monkeys was used as the healthy control. All monkeys underwent a CMR study to measure global longitudinal strain (GLS), myocardial extracellular volume (ECV), and late gadolinium enhancement (LGE). In healthy controls and HFpEF group, quantitative perfusion imaging scans at rest and under dobutamine stress were performed and myocardial perfusion reserve (MPR) was subsequently obtained. No LGE was observed in any monkey. Monkeys with HF-like features were significantly older, compared to the healthy control group. There were significant differences among the three groups in ECV (20.79 ± 3.65% in healthy controls; 27.06 ± 3.37% in HFpEF group, and 31.11 ± 4.50% in HFrEFgroup, p < 0.001), as well as for stress perfusion (2.40 ± 0.34 ml/min/g in healthy controls vs. 1.28 ± 0.24 ml/min/g in HFpEF group, p < 0.01) and corresponding MPR (1.83 ± 0.3 vs. 1.35 ± 0.29, p < 0.01). After adjusting for age, ECV (p = 0.01) and MPR (p = 0.048) still showed significant differences among the three groups. Our preliminary imaging findings demonstrated cardiac dysfunction, elevated ECV, and/or reduced MPR in this HF-like NHP model. This pilot study laid the foundation for further mechanistic research and the development of a drug testing platform for distinct HF pathophysiology.

Abstract P2139: The Adiponectin Receptor Agonist ALY688 Prevents Pressure Overload-induced Cardiac Dysfunction And Adverse Cardiac Remodeling

Adiponectin has been shown to mediate multiple cardioprotective effects. Since the use of adiponectin protein as a practical therapeutic is associated with multiple challenges, we examined the functional significance of targeting adiponectin signaling with ALY688, a small peptide-based adiponectin mimetic, in a mouse model of cardiac dysfunction caused by left ventricular pressure overload (PO) induced by minimally invasive transverse aortic banding (MTAB). Following daily administration of ALY688 over 5 weeks after induction of PO, echocardiography showed that significantly attenuated PO-induced reduction in ejection fraction and other indices of cardiac function compared with vehicle. ALY688 also significantly reduced cardiac hypertrophic remodeling (heart weight-to-tibia length), cardiomyocyte cross sectional area, and myocardial and circulating levels of serum natriuretic peptide A. ALY688 reduced PO-induced increases in myofibroblasts, and scar tissue collagen content based upon immunofluorescence staining for α-smooth muscle actin and vimentin, scanning electron microscopy, and picrosirius red staining. ALY688 reduced PO-induced myocardial expression of 14 pro-inflammatory genes and circulating IL-12, IL-15, IL-17, and MIP-3α levels. Targeted metabolomics revealed that ALY688 increased myocardial fatty acid oxidation, with increased mobilization of cardiac triacylglycerols and a decrease in sphingomyelin, fatty acids and lysophospholipids. In conclusion, the adiponectin analogue ALY688 is cardioprotective in a preclinical animal model of heart failure and cardiac remodeling, with beneficial metabolic, anti-fibrotic, anti-hypertrophic and anti-inflammatory properties leading to improved cardiac function.

Abstract P1024: Cardiomyocyte Mechanics In Animal Models Of Heart Failure With Preserved Ejection Fraction

Heart failure with preserved ejection fraction (HFpEF) has few effective therapies yet exacts substantial mortality. Its multi-system nature has made animal modeling difficult, but recent efforts combining diet-induced obesity and hemodynamic stress are popular: mouse - L-NAME/high-fat diet (HFD) and ovariectomized (OVX) females with HFD-induced obesity/cardiac pressure overload (PO) (HFD+OVX+PO), ZSF1 rat, and obese/hypertensive Göttingen minipigs. We reported human HFpEF myocyte defects including reduced Ca 2+ -activated maximum tension (T max ) negatively correlate with body mass index, reduced Hill coefficient (n H, e.g., cooperativity) and Ca 2+ at 50% T max (EC 50 ), and higher resting tension. Here we tested whether such deficits are found in HFpEF animal models. The L-NAME/HFD mouse had no differences in Ca 2+ -activated (p=0.20) or resting (p=0.75) tension. In obese ZSF-1 rats, while T max (p=0.23) and resting tension (p=0.39) were not different, n H was reduced (2±1 vs. 4±2 p=0.01). In HFD+OVX+PO mice, T max (15±2 vs. 20±2 mN/mm 2 , p=0.006) and EC 50 (1.9±0.6 vs. 2.4±0.7 μM, p=0.008) were reduced, but resting tension (p=0.70) was not different. In the Göttingen minipig HFpEF model, EC 50 (p=0.93) and n H (p=0.35) were not different, whereas T max was reduced (17±3 vs. 27±3 mN/mm 2 , p=2x10 -6 ) and tension less at physiologic Ca 2+ . Resting tension was lower (not greater) in this model (p=0.001). The HFD+OVX+PO and minipig HFpEF models recapitulate depressed Ca 2+ -activated tension as in obese human HFpEF, whereas none manifested increased resting tension ( Table 1 ). Studies investigating HFpEF sarcomere dysfunction should consider these findings in model selection.

Effects of Triiodothyronine Treatment in an Animal Model of Heart Failure with Preserved Ejection Fraction.

Background: Low levels of triiodothyronine (T3) are common in patients with heart failure (HF). Our aim was to evaluate the effects of supplementation with low and replacement doses of T3 in an animal model of HF with preserved ejection fraction (HFpEF). Methods: We evaluated four groups: ZSF1 Lean (n = 8, Lean-Ctrl), ZSF1 Obese (rat model of metabolic-induced HFpEF, n = 13, HFpEF), ZSF1 Obese treated with a replacement dose of T3 (n = 8, HFpEF-T3high), and ZSF1 Obese treated with a low-dose of T3 (n = 8, HFpEF-T3low). T3 was administered in drinking water from weeks 13 to 24. The animals underwent anthropometric and metabolic assessments, echocardiography, and peak effort testing with maximum O2 consumption (VO2max) determination at 22 weeks, and a terminal hemodynamic evaluation at 24 weeks. Afterwhile myocardial samples were collected for single cardiomyocyte evaluation and molecular studies. Results: HFpEF animals showed lower serum and myocardial thyroid hormone levels than Lean-Ctrl. Treatment with T3 did not normalize serum T3 levels, but increased myocardial T3 levels to normal levels in the HFpEF-T3high group. Body weight was significantly decreased in both the T3-treated groups, comparing with HFpEF. An improvement in glucose metabolism was observed only in HFpEF-T3high. Both the treated groups had improved diastolic and systolic function in vivo, as well as improved Ca2+ transients and sarcomere shortening and relaxation in vitro. Comparing with HFpEF animals, HFpEF-T3high had increased heart rate and a higher rate of premature ventricular contractions. Animals treated with T3 had higher myocardial expression of calcium transporter ryanodine receptor 2 (RYR2) and α-myosin heavy chain (MHC), with a lower expression of β-MHC. VO2max was not influenced by treatment with T3. Myocardial fibrosis was reduced in both the treated groups. Three animals died in the HFpEF-T3high group. Conclusions: Treatment with T3 was shown to improve metabolic profile, myocardial calcium handling, and cardiac function. While the low dose was well-tolerated and safe, the replacement dose was associated with increased heart rate, and increased risk of arrhythmias and sudden death. Modulation of thyroid hormones may be a potential therapeutic target in HFpEF; however, it is important to take into account the narrow therapeutic window of T3 in this condition.

Circulating sphingolipids in heart failure.

Lack of significant advancements in early detection and treatment of heart failure have precipitated the need for discovery of novel biomarkers and therapeutic targets. Over the past decade, circulating sphingolipids have elicited promising results as biomarkers that premonish adverse cardiac events. Additionally, compelling evidence directly ties sphingolipids to these events in patients with incident heart failure. This review aims to summarize the current literature on circulating sphingolipids in both human cohorts and animal models of heart failure. The goal is to provide direction and focus for future mechanistic studies in heart failure, as well as pave the way for the development of new sphingolipid biomarkers.

Circulating immune checkpoints predict heart failure outcomes.

There are limited data examining the role of immune checkpoint (IC) ligands in the pathophysiology of heart failure (HF). Therefore, we explore this in three HF animal models and in three different human cohorts (healthy, stable, and worsening HF). Transcriptomic analyses of cardiac tissue of three different HF mouse models revealed differentially expressed IC receptors and their ligands compared with control mice. Based on this observation, serum levels of three well-known IC ligands (i.e. sPD-L1, sPD-L2 and galectin-9) were measured in stable HF patients from the Vitamin D Chronic Heart Failure (VitD-CHF) study (n=101), as well as healthy individuals from the Prevention of Renal and Vascular End-stage Disease (PREVEND) study (n=58). sPD-L1, sPD-L2, and galectin-9 were all associated with New York Heart Association classification. In multivariate linear regression analyses, all three IC ligands were associated with galectin-3 (β=0.230, β=0.283, and β=0.304, respectively). sPD-L1 and galectin-9 were also associated with hs-troponin-T (β=0.386 and β=0.314). Regarding prognosis, higher serum levels of sPD-L1 and galectin-9 were significantly associated with increased risk for HF hospitalization and all-cause mortality [hazard ratio 1.69 (1.09-2.59) and hazard ratio 1.50 (1.06-2.12)]. Furthermore, the importance of IC ligands was tested in another stage of HF, namely worsening HF patients. In the worsening HF cohort (The BIOlogy Study to Tailored Treatment in Chronic Heart Failure) (n=2032), sPD-L2 and galectin-9 were associated with New York Heart Association classification and significantly predicted outcome with an increased relative risk of 15% and 20%, after multivariable adjustment, respectively. IC ligands are expressed in cardiac disease models, and serum levels of IC ligands are elevated in HF patients, are associated with disease severity, and significantly predict prognosis. These data indicate a potential role for IC ligands in HF pathogenesis.

Understanding the Role of Vitamin D in Heart Failure

Vitamin D is now believed to have a significant role in cardiac signal transduction and regulation of gene expression, and thus influences normal cardiomyocyte function. It has been reported to provide cardioprotection through its anti-inflammatory, anti-apoptotic and anti-fibrotic actions; and to prevent cardiac remodeling, Ca2+-handling defects, and abnormal electrophysiological patterns. A vitamin D deficient state has been associated in the pathogenesis of heart failure; however, while many clinical studies report a benefit of vitamin D to heart function, other clinical studies are inconsistent with these findings. These uncertainties have led to a discord in the recommendation of vitamin D supplementation for the treatment of heart failure or as a preventive agent in patients deemed to be at risk for cardiac dysfunction. Accordingly, this article is intended to describe some of the mechanisms/sites of action of vitamin D in different animal models of heart failure, as well as to review the clinical observations and challenges in the interpretation and understanding of the clinical relevance of vitamin D in relation to heart function.

The circadian clock remains intact, but with dampened hormonal output in heart failure

Circadian (24-h) rhythms are important regulators in physiology and disease, but systemic disease may disrupt circadian rhythmicity. Heart failure (HF) is a systemic disease affecting hormonal regulation. We investigate whether HF affects the rhythmic expression of melatonin and cortisol, main endocrine products of the central clock, and cardiac-specific troponin in patients. We corroborate the functionality of the peripheral clock directly in the organs of translational models, inaccessible in human participants. We included 46 HF patients (71.7% male, median age of 60 years, NYHA class II (32.6%) or III (67.4%), ischemic cardiomyopathy (43.5%), comorbidities: diabetes 21.7%, atrial fibrillation 30.4%), and 24 matched controls. Blood was collected at seven time-points during a 24-h period (totalling 320 HF and 167 control samples) for melatonin, cortisol, and cardiac troponin T (cTnT) measurements after which circadian rhythms were assessed through cosinor analyses, both on the individual and the group level. Next, we analysed peripheral circadian clock functionality using cosinor analysis in male animal HF models: nocturnal mice and diurnal zebrafish, based on expression of core clock genes in heart, kidneys, and liver, every 4h during a 24-h period in a light/darkness synchronised environment. Melatonin and cortisol concentrations followed a physiological 24-h pattern in both patients and controls. For melatonin, acrophase occurred during the night for both groups, with significantly decreased amplitude (median 5.2 vs 8.8, P=0.0001) and circadian variation ([maximum]/[minimum]) in heart failure patients. For cortisol, mesor showed a significant increase for HF patients (mean 331.9 vs 275.1, P=0.017) with a difference of 56.8 (95% CI 10.3-103.3) again resulting in a relatively lower variation: median 3.9 vs 6.3 (P=0.0058). A nocturnal blood pressure dip was absent in 77.8% of HF patients. Clock gene expression profiles (Bmal, Clock, Per, Cry) were similar and with expected phase relations in animal HF models and controls, demonstrating preserved peripheral clock functionality in HF. Furthermore, oscillations in diurnal zebrafish were expectedly in opposite phases to those of nocturnal mice. Concordantly, cTnT concentrations in HF patients revealed significant circadian oscillations. Central clock output is dampened in HF patients while the molecular peripheral clock, as confirmed in animal models, remains intact. This emphasises the importance of taking timing into account in research and therapy for HF, setting the stage for another dimension of diagnostic, prognostic and therapeutic approaches. Hartstichting.

Ascites in Animals With Right Heart Failure: Correlation With Lymphatic Dysfunction.

Background Congestive heart failure is a leading cause of morbidity and mortality worldwide. One of the signs of congestive heart failure is fluid overload including pulmonary edema, peripheral edema, and ascites. The cause of fluid overload remains incompletely understood, and management of these patients continues to be a challenge. The role of lymphatic circulation abnormalities in the cause and pathophysiology of fluid overload also remains unclear. Here we report on a study in a large animal model of right heart failure caused by severe tricuspid regurgitation comparing cardiovascular and lymphatic findings in a group of animals that did not develop ascites with a group of animals that developed ascites. Methods and Results Thirteen Yorkshire pigs were included in this study divided into 2 groups. Group 1 included 6 animals that did not develop ascites, and Group 2 included 7 animals that had developed ascites. The groups were compared on hemodynamic parameters as well as comparison of the animal's lymphatic anatomy and function. There was no difference between the groups in degree of tricuspid regurgitation and central venous pressure, with inferior vena cava pressure measuring 11.6±1.6 versus 13.2±3.7 (P=0.534) and superior vena cava pressure measuring 12.0±2.3 versus 13.7±3.2 (P=0.366). There was also no difference between the groups in all measured hemodynamic parameters, including right ventricular pressure, pulmonary artery pressure, and left ventricular function. The weighted liver size in the ascites group was significantly larger than in the nonascites group (30.3±12.4 versus 63.3±14.0 mL/kg, respectively; P=0.001). The 2 groups also differed in the number of animals with regurgitant thoracic duct flow (Group 1: 1/6,17% versus Group 2: 6/7, 86%; P=0.029) and the minimal thoracic duct diameter (Group 1: 2.3±0.3 versus Group 2: 4.2±2.2; P=0.035). Conclusions In animals with right heart failure caused by severe tricuspid regurgitation, fluid overload did not correlate with hemodynamic parameters but rather with changes in the lymphatic system, including regurgitant lymphatic flow, minimal thoracic duct diameter, and liver size. This study is consistent with lymphatic dysfunction and not cardiovascular function playing a significant role in the cause of fluid overload. Further studies are needed to confirm these findings.