Pressure Overload-induced Heart Failure Research Articles

Exploring biomarkers and therapeutic targets for pressure overload induced heart failure based on microarray data.

Heart failure (HF) is an end stage heart condition with poor prognosis which brings about tremendous social medical cost. Along decades, mechanism and treatments of HF have been under restless research. In the present study, we first established pressure overload induced HF model using transaortic arch constriction (TAC) method in mice. The global expression profiles of long noncoding RNA (lncRNA), microRNA (miRNA) and messenger RNA (mRNA) were obtained by microarray probes, which were further confirmed by quantitative PCR (qPCR). Bioinformatics analysis was performed using multiple methods including volcano plotting, heatmapping and hierarchical clustering, Gene Ontology (GO) and pathway enrichment analysis, and competing endogenous RNA (ceRNA) regulatory network construction. Totally, 1,139 differentially expressed mRNAs (DEmRNAs), 3,830 lncRNAs (DElncRNAs) and 13 miRNAs (DEmiRNAs) were identified in HF group compared to control group, which could distinctly differentiate HF from normal control and were potential candidate biomarkers for HF. GO and pathway enrichment analysis revealed that multiple significant biological processes and pathways were involved in HF pathogenesis, such as extracellular matrix structural constituent, proteinaceous extracellular matrix, positive regulation of apoptotic process and integrin signaling pathway. Nine DElncRNAs, 3 DEmiRNAs and 25 DEmRNAs were filtrated out to construct a ceRNA network, which visually displayed their regulatory roles with therapeutic target potential. The present study identified differentially expressed RNAs that might be involved in the pathogenesis and progression of HF. The outcomes shed lights into the underlying mechanisms for HF and provided candidate biomarkers and intervention targets for further research.

Stimulation of exosome biogenesis by adiponectin, a circulating factor secreted from adipocytes.

Adiponectin is an adipocyte-derived circulating factor that protects various organs and tissues. Such a pleiotropic action mechanism has not yet been fully explained. Clinically important multimer adiponectin existing in serum bound to cells expressing T-cadherin, a glycosylphosphatidylinositol-anchored cadherin, but not to the cells expressing other known receptors, AdipoRs or calreticulin. Adiponectin bound to the cell-surface, accumulated inside of multivesicular bodies through T-cadherin, and increased exosome biogenesis and secretion from the cells. Such increased exosome production accompanied the reduction of cellular ceramides in endothelial cells and mouse aorta, and enhanced skeletal muscle regeneration. Significantly lower plasma exosome levels were found in mice genetically deficient in either adiponectin or T-cadherin. Therapeutic effects of mesenchymal stem cells (MSCs) for a pressure overload-induced heart failure in mice required the presence of adiponectin in plasma, T-cadherin expression and exosome biogenesis in MSCs themselves, accompanying an increase of plasma exosomes. Essentially all organs seem to have MSCs and/or their related somatic stem cells expressing T-cadherin. Our recent studies suggested the importance of exosome-stimulation by multimer adiponectin in its well-known pleiotropic organ protections.

LCZ696 Ameliorates Oxidative Stress and Pressure Overload-Induced Pathological Cardiac Remodeling by Regulating the Sirt3/MnSOD Pathway.

Aims We aimed to investigate whether LCZ696 protects against pathological cardiac hypertrophy by regulating the Sirt3/MnSOD pathway. Methods In vivo, we established a transverse aortic constriction animal model to establish pressure overload-induced heart failure. Subsequently, the mice were given LCZ696 by oral gavage for 4 weeks. After that, the mice underwent transthoracic echocardiography before they were sacrificed. In vitro, we introduced phenylephrine to prime neonatal rat cardiomyocytes and small-interfering RNA to knock down Sirt3 expression. Results Pathological hypertrophic stimuli caused cardiac hypertrophy and fibrosis and reduced the expression levels of Sirt3 and MnSOD. LCZ696 alleviated the accumulation of oxidative reactive oxygen species (ROS) and cardiomyocyte apoptosis. Furthermore, Sirt3 deficiency abolished the protective effect of LCZ696 on cardiomyocyte hypertrophy, indicating that LCZ696 induced the upregulation of MnSOD and phosphorylation of AMPK through a Sirt3-dependent pathway. Conclusions LCZ696 may mitigate myocardium oxidative stress and apoptosis in pressure overload-induced heart failure by regulating the Sirt3/MnSOD pathway.

Modulation of P2Y6R expression exacerbates pressure overload-induced cardiac remodeling in mice

Cardiac tissue remodeling caused by hemodynamic overload is a major clinical outcome of heart failure. Uridine-responsive purinergic P2Y6 receptor (P2Y6R) contributes to the progression of cardiovascular remodeling in rodents, but it is not known whether inhibition of P2Y6R prevents or promotes heart failure. We demonstrate that inhibition of P2Y6R promotes pressure overload-induced sudden death and heart failure in mice. In neonatal cardiomyocytes, knockdown of P2Y6R significantly attenuated hypertrophic growth and cell death caused by hypotonic stimulation, indicating the involvement of P2Y6R in mechanical stress-induced myocardial dysfunction. Unexpectedly, compared with wild-type mice, deletion of P2Y6R promoted pressure overload-induced sudden death, as well as cardiac remodeling and dysfunction. Mice with cardiomyocyte-specific overexpression of P2Y6R also exhibited cardiac dysfunction and severe fibrosis. In contrast, P2Y6R deletion had little impact on oxidative stress-mediated cardiac dysfunction induced by doxorubicin treatment. These findings provide overwhelming evidence that systemic inhibition of P2Y6R exacerbates pressure overload-induced heart failure in mice, although P2Y6R in cardiomyocytes contributes to the progression of cardiac fibrosis.

Longitudinal Strain Reflects Ventriculoarterial Coupling Rather Than Mere Contractility in Rat Models of Hemodynamic Overload–Induced Heart Failure

Longitudinal strain (LS) is a sensitive marker of systolic function. Recent findings suggest that both myocardial contractility and loading conditions determine LS. The aim of this study was to investigate whether LS reflects the connection of cardiac contractility to afterload (termed ventriculoarterial coupling [VAC]) rather than mere contractility in rat models of hemodynamic overload-induced heart failure (HF). Pressure overload-induced HF was evoked by transverse aortic constriction (TAC; n=14). Volume overload-induced HF was established by an aortocaval fistula (ACF; n=12). Age-matched sham-operated animals served as controls for TAC (n=14) and ACF (n=12), respectively. Pressure-volume analysis was carried out to compute contractility (slope of end-systolic pressure-volume relationship [ESPVR]), afterload (arterial elastance [Ea]), and VAC (Ea/ESPVR). Preload was evaluated by meridional end-diastolic wall stress. Speckle-tracking echocardiography was performed to assess LS. The TAC group presented with maintained ESPVR, increased Ea, and enhanced meridional end-diastolic wall stress. In contrast, the ACF group was characterized by reduced ESPVR, decreased Ea, and enhanced meridional end-diastolic wall stress. VAC increased in both HF groups. Furthermore, LS was also impaired in both HF models (-5.9±0.6% vs -12.9±0.5%, TAC vs Shamt [P<.001], and -11.7±0.7% vs -13.5±0.4%, ACF vs Shama[P=.048]). Statistical analysis revealed that strain parameters were determined predominantly by afterload in the TAC group and by contractility in the ACF group, while preload had a minor effect. In the entire study population, LS showed a correlation with VAC (R=0.654, P<.001) but not with ESPVR (R=0.058, P=.668). Under pathophysiologic conditions when both contractility and afterload become altered, LS reflects VAC rather than mere contractility.

Genomic characterization reveals novel mechanisms underlying the valosin-containing protein-mediated cardiac protection against heart failure

Chronic hypertension is a key risk factor for heart failure. However, the underlying molecular mechanisms are not fully understood. Our previous studies found that the valosin-containing protein (VCP), an ATPase-associated protein, was significantly decreased in the hypertensive heart tissues. In this study, we tested the hypothesis that restoration of VCP protected the heart against pressure overload-induced heart failure. With a cardiac-specific transgenic (TG) mouse model, we showed that a moderate increase of VCP was able to attenuate chronic pressure overload-induced maladaptive cardiac hypertrophy and dysfunction. RNA sequencing and a comprehensive bioinformatic analysis further demonstrated that overexpression of VCP in the heart normalized the pressure overload-stimulated hypertrophic signals and repressed the stress-induced inflammatory response. In addition, VCP overexpression promoted cell survival by enhancing the mitochondria resistance to the oxidative stress via activating the Rictor-mediated-gene networks. VCP was also found to be involved in the regulation of the alternative splicing and differential isoform expression for some genes that are related to ATP production and protein synthesis by interacting with long no-coding RNAs and histone deacetylases, indicating a novel epigenetic regulation of VCP in integrating coding and noncoding genomic network in the stressed heart. In summary, our study demonstrated that the rescuing of a deficient VCP in the heart could prevent pressure overload-induced heart failure by rectifying cardiac hypertrophic and inflammatory signaling and enhancing the cardiac resistance to oxidative stress, which brought in novel insights into the understanding of the mechanism of VCP in protecting patients from hypertensive heart failure.

Myocardial tissue-specific Dnmt1 knockout in rats protects against pathological injury induced by Adriamycin

Novel molecular mechanisms of the pathophysiology of heart failure (HF) are continuously being discovered, including epigenetic regulation. Among epigenetic marks, the role of DNA hypomethylation in shaping heart morphology and function in vivo and the pathogenesis of cardiomyopathy and/or HF, especially in adults, has not been clearly established. Here we show that the strong expression of DNA methyltransferase 1 (Dnmt1) is obviously downregulated in the WT adult rat heart with age. By contrast, the expression of Dnmt1 is upregulated suddenly in heart tissues from pressure overload-induced HF mice and adriamycin-induced cardiac injury and HF mice, consistent with the increased expression of Dnmt1 observed in familial hypertrophic cardiomyopathy (FHCM) patients. To further assess the role of Dnmt1, we generated myocardium-specific Dnmt1 knockout (Dnmt1 KO) rats using CRISPR-Cas9 technology. Echocardiographic and histopathological examinations demonstrated that Dnmt1 deficiency is associated with resistance to cardiac pathological changes and protection at the global and organization levels in response to pathological stress. Furthermore, Dnmt1 deficiency in the myocardium restricts the expressional reprogramming of genes and activates pathways involved in myocardial protection and anti-apoptosis in response to pathological stress. Transcriptome and genome-wide DNA methylation analyses revealed that these changes in regulation are linked to alterations in the methylation status of genes due to Dnmt1 knockout. The present study is the first to investigate in vivo the impact of genome-wide cardiac DNA methyltransferase deficiency on physiological development and the pathological processes of heart tissues in response to stress. The exploration of the role of epigenetics in the development, modification, and prevention of cardiomyopathy and HF is in a very preliminary stage but has an infinite future.

Nuclear localization of a novel calpain-2 mediated junctophilin-2 C-terminal cleavage peptide promotes cardiomyocyte remodeling.

Heart failure (HF) is a leading cause of morbidity and mortality worldwide. Patients with HF exhibit a loss of junctophilin-2 (JPH2), a structural protein critical in forming junctional membrane complexes in which excitation-contraction takes place. Several mechanisms have been proposed to mediate the loss of JPH2, one being cleavage by the calcium-dependent protease calpain. The downstream mechanisms underlying HF progression after JPH2 cleavage are presently poorly understood. In this study, we used Labcas to bioinformatically predict putative calpain cleavage sites on JPH2. We identified a cleavage site that produces a novel C-terminal JPH2 peptide (JPH2-CTP) using several domain-specific antibodies. Western blotting revealed elevated JPH2-CTP levels in hearts of patients and mice with HF, corresponding to increased levels of calpain-2. Moreover, immunocytochemistry demonstrated nuclear localization of JPH2-CTP within ventricular myocytes isolated from a murine model of pressure overload-induced HF as well as rat ventricular myocytes treated with isoproterenol. Nuclear localization of JPH2-CTP and cellular remodeling were abrogated by a genetic mutation of the nuclear localization sequence within JPH2-CTP. Taken together, our studies identified a novel C-terminal fragment of JPH2 (JPH2-CTP) generated by calpain-2 mediated cleavage which localizes within the cardiomyocyte nucleus during HF. Blocking nuclear localization of JPH2-CTP protects cardiomyocytes from isoproterenol-induced hypertrophy in vitro. Future in vivo studies of the nuclear role of JPH2-CTP may reveal a causal association with adverse remodeling during HF and establish CTP as a therapeutic target.

Molecular Mechanism of HSF1-Upregulated ALDH2 by PKC in Ameliorating Pressure Overload-Induced Heart Failure in Mice.

Evidences abound that HSF1 and ALDH2 are of cardioprotective effect, yet there is still no report on whether HSF1 can regulate ALDH2 to delay the occurrence of heart failure. We first established the pressure overload-induced heart failure model of mice by transverse aortic constriction (TAC) and discovered that, in the forming period of heart failure, changes of HSF1 and ALDH2 expression recorded the consistent trend. When HSF1 was upregulated/downregulated to delay/promote the occurrence of heart failure, PKC and ALDH2 also showed increased/decreased expression. And when ALDH2 was upregulated/downregulated, the role of HSF1 in delaying the occurrence of heart failure strengthened/weakened. Next, we used mechanical stretch to establish a pressure-stimulated myocardial hypertrophy model and discovered an increased expression of both HSF1 and ALDH2. When HSF1 was upregulated/downregulated to increase/decrease the expression of myocardial hypertrophy gene beta-MHC, PKC and ALDH2 recorded an increased/decreased expression. When an inhibitor was used to downregulate the expression of PKC in cardiomyocytes, we found that the role of HSF1 in upregulating ALDH2 beta-MHC weakened. These findings suggest that HSF1 can upregulate the expression of ALDH2 via PKC to promote pressure-stimulated myocardial compensatory hypertrophy, which is an important molecular pathway for HSF1 to ameliorate heart failure.

Peroxiredoxin-1 ameliorates pressure overload-induced cardiac hypertrophy and fibrosis

BackgroundPrevious studies have demonstrated that Peroxiredoxin 1 (Prdx1) is a modulator of physiological and pathophysiological cardiovascular events. However, the roles of Prdx1 in cardiac hypertrophy and heart failure (HF) have barely been explored. Thus, this study aimed to investigate whether Prdx1 participates in cardiac hypertrophy and to elucidate the possible associated mechanisms. MethodsMice were subjected to transverse aortic constriction (TAC) for four weeks to induce pathological cardiac hypertrophy. Cardiomyocyte-specific Prdx1 overexpression in mice was achieved using an adeno-associated virus system. Morphological examination; echocardiography; and hemodynamic, biochemical and histological analyses were used to evaluate the roles of Prdx1 in pressure overload-induced cardiac hypertrophy and HF. ResultsFirst, the results showed that Prdx1 expression was noticeably upregulated in hypertrophic mouse hearts and cardiomyocytes with phenylephrine (PE)-induced hypertrophy in vitro. Prdx1 overexpression exerted protective effects against cardiac hypertrophy and fibrosis and ameliorated cardiac dysfunction in mice subjected to pressure overload. In addition, Prdx1 overexpression decreased pressure overload-induced cardiac inflammation and oxidative stress. Further studies demonstrated that Prdx1 overexpression increased the levels of nuclear factor-erythroid 2-related factor 2 (Nrf2) and its downstream antioxidant protein, heme oxygenase-1 (HO-1), in mice. Moreover, Nrf2 knockdown offset the antihypertrophic and anti-oxidative stress effects of Prdx1 overexpression. ConclusionsPrdx1 protects against pressure overload-induced cardiac hypertrophy and HF by activating Nrf2/HO-1 signaling. These data indicate that targeting Prdx1 may be an attractive pharmacotherapeutic strategy for the treatment of cardiac hypertrophy and HF.

Endothelial Sirtuin 3 Dictates Glucose Transport to Cardiomyocyte and Sensitizes Pressure Overload-Induced Heart Failure.

BackgroundAlterations of energetic metabolism are suggested to be an important contributor to pressure overload (PO)‐induced heart failure. Our previous study reveals that knockout of endothelial Sirtuin 3 (SIRT3) alters glycolysis and impairs diastolic function. We hypothesize that endothelial SIRT3 regulates glucose utilization of cardiomyocytes and sensitizes PO‐induced heart failure.Methods and Results SIRT3 endothelial cell knockout mice and their control SIRT3 LoxP mice were subjected to PO by transverse aortic constriction for 7 weeks. The ratio of heart weight to tibia length was increased in both strains of mice, in which SIRT3 endothelial cell knockout mice+transverse aortic constriction exhibited more severe cardiac hypertrophy. Coronary blood flow and systolic function were significantly decreased in SIRT3 endothelial cell knockout mice+transverse aortic constriction compared with SIRT3 LoxP mice+transverse aortic constriction, as evidenced by lower systolic/diastolic ratio, ejection fraction, and fractional shortening. PO‐induced upregulation of apelin and glucose transporter 4 were significantly reduced in the hearts of SIRT3 endothelial cell knockout mice. In vitro, levels of hypoxia‐inducible factor‐1α and glucose transporter 1 and glucose uptake were significantly reduced in SIRT3 knockout endothelial cells. Furthermore, hypoxia‐induced apelin expression was abolished together with reduced apelin‐mediated glucose uptake in SIRT3 knockout endothelial cells. Exposure of cardiomyocyte with apelin increased expression of glucose transporter 1 and glucose transporter 4. This was accompanied by a significant increase in glycolysis. Supplement of apelin in SIRT3 knockout hypoxic endothelial cell media increased glycolysis in the cardiomyocytes.ConclusionsKnockout of SIRT3 disrupts glucose transport from endothelial cells to cardiomyocytes, reduces cardiomyocyte glucose utilization via apelin in a paracrine manner, and sensitizes PO‐induced heart failure. Endothelial SIRT3 may regulate cardiomyocyte glucose availability and govern the function of the heart.

Manipulation of beta-adrenergic receptor in pressure-overloaded murine hearts mimics adverse and reverse cardiac remodeling

Transverse aortic constriction (TAC) has been widely used to create pressure overload induced heart failure in mice. However, this conventional model has some limitations such as low reproducibility and long creation period of cardiac failure.In order to establish a highly reproducible cardiac failure model that mimics adverse cardiac remodeling (ACR) we combined pressure overload and beta-adrenergic receptor stimuli using isoproterenol (ISO) and explored the optimal TAC model by changing the durations of TAC and the doses of ISO. Thus we constructed a suitable model for ACR with an effective combination of 3-week TAC and subsequent one-week ISO (3 mg/kg/day) infusion. Using RNA-Seq analyses, we identified that the up-regulated genes were mainly related to fibrosis including Fbn1, C1qtnf6 and Loxl2; and that the down-regulated genes were associated with mitochondrial function including Uqcrc1, Ndufs3, and Idh2 in failing hearts of our ACR model. Next, we followed the changes in cardiac function after ceasing ISO infusion. Left ventricular function gradually recovered after cessation of ISO, suggesting cardiac reverse remodeling (CRR). Gene expression signatures of hearts, which exhibited CRR, were almost identical to that of TAC hearts without ISO. In conclusion, our new model exhibits a transition to ACR and subsequent CRR with high reproducibility. This murine model might add new insights into the experiments of heart failure technically as well as scientifically.

Chemogenetic activation of intracardiac cholinergic neurons improves cardiac function in pressure overload-induced heart failure.

Heart failure (HF) is characterized by autonomic imbalance with sympathetic hyperactivity and loss of parasympathetic tone. Intracardiac ganglia (ICG) neurons represent the final common pathway for vagal innervation of the heart and strongly regulate cardiac functions. This study tests whether ICG cholinergic neuron activation mitigates the progression of cardiac dysfunction and reduces mortality that occurs in HF. HF was induced by transaortic constriction (TAC) in male transgenic Long-Evans rats expressing Cre recombinase within choline acetyltransferase (ChAT) neurons. ChAT neurons were selectively activated by expression and activation of excitatory designer receptors exclusively activated by designer receptors (DREADDs) by clozapine-N-oxide (TAC + treatment and sham-treated groups). Control animals expressed DREADDs but received saline (sham and TAC groups). A separate set of animals were telemetry instrumented to record blood pressure (BP) and heart rate (HR). Acute activation of ICG neurons resulted in robust reductions in BP (∼20 mmHg) and HR (∼100 beats/min). All groups of animals were subjected to weekly echocardiography and treadmill stress tests from 3 to 6 wk post-TAC/sham surgery. Activation of ICG cholinergic neurons reduced the left ventricular systolic dysfunction (reductions in ejection fraction, fractional shortening, stroke volume, and cardiac output) and cardiac autonomic dysfunction [reduced HR recovery (HRR) post peak effort] observed in TAC animals. Additionally, activation of ICG ChAT neurons reduced mortality by 30% compared with untreated TAC animals. These data suggest that ICG cholinergic neuron activation reduces cardiac dysfunction and improves survival in HF, indicating that ICG neuron activation could be a novel target for treating HF.NEW & NOTEWORTHY Intracardiac ganglia form the final common pathway for the parasympathetic innervation of the heart. This study has used a novel chemogenetic approach within transgenic ChAT-Cre rats [expressing only Cre-recombinase in choline acetyl transferase (ChAT) neurons] to selectively increase intracardiac cholinergic parasympathetic activity to the heart in a pressure overload-induced heart failure model. The findings from this study confirm that selective activation of intracardiac cholinergic neurons lessens cardiac dysfunction and mortality seen in heart failure, identifying a novel downstream cardiac-selective target for increasing cardioprotective parasympathetic activity in heart failure.

Cytosolic DNA sensor cGAS plays an essential pathogenetic role in pressure overload-induced heart failure.

Growing evidence shows that activation of inflammation in the heart provokes left ventricular (LV) remodeling and dysfunction in humans and experimental animals with heart failure (HF). Moreover, recent studies found that cyclic GMP-AMP synthase (cGAS), serving as a cytosolic DNA sensor, was essential for activating innate immunity against infection and cellular damage by initiating the STING-IRFs-type I IFN signaling cascade, which played important roles in regulating the inflammatory response. However, the pathophysiological role of cGAS in pressure overload-induced HF is unclear. Wild-type C57BL/6J mice and cGAS inhibition mice were subjected to transverse aortic constriction (TAC) to induce HF or sham operation. Inhibition of cGAS in the murine heart was performed using adeno-associated virus 9 (AAV9). Alterations of the cGAS/STING pathway were examined by qPCR and Western blotting. Cardiac remodeling was assessed by echocardiography as well as histological and molecular phenotyping. Compared with sham-operated mice, the cGAS/STING pathway was activated in LV tissues in TAC mice. Whereas TAC mice exhibited significant pathological cardiac remodeling and LV dysfunction, inhibition of cGAS improved early survival rates after TAC, preserved LV contractile function, and blunted pathological remodeling, including cardiac hypertrophy, fibrosis, and apoptosis. Furthermore, downregulation of cGAS diminished early inflammatory cell infiltration and inflammatory cytokine expression in response to TAC. These results demonstrated that cGAS played an essential pathogenetic role in pressure overload-induced HF to promote pathological cardiac remodeling and dysfunction. Our results suggest that inhibition of cGAS may be a novel therapeutic approach for HF.NEW & NOTEWORTHY In this study, we first revealed a novel role of cGAS in the regulation of pathological cardiac remodeling and dysfunction upon pressure overload. We found that the cGAS/STING pathway was activated during pressure overload. Moreover, we also demonstrated that inhibition of the cGAS/STING pathway alleviated pathological cardiac remodeling and downregulated the early inflammatory response during pressure overload-induced HF. Together, these findings will provide a new therapeutic target for HF.

The Synthetic Curcumin Analogue GO-Y030 Effectively Suppresses the Development of Pressure Overload-induced Heart Failure in Mice

Curcumin is a naturally occurring p300-histone acetyltransferase (p300-HAT) inhibitor that suppresses cardiomyocyte hypertrophy and the development of heart failure in experimental animal models. To enhance the therapeutic potential of curcumin against heart failure, we produced a series of synthetic curcumin analogues and investigated their inhibitory activity against p300-HAT. The compound with the strongest activity was further evaluated to determine its effects on cardiomyocyte hypertrophy and pressure overload-induced heart failure in mice. We synthesised five synthetic curcumin analogues and found that a compound we have named GO-Y030 most strongly inhibited p300-HAT activity. Furthermore, 1 μM GO-Y030, in a manner equivalent to 10 µM curcumin, suppressed phenylephrine-induced hypertrophic responses in cultured cardiomyocytes. In mice undergoing transverse aortic constriction surgery, administration of GO-Y030 at a mere 1% of an equivalently-effective dose of curcumin significantly attenuated cardiac hypertrophy and systolic dysfunction. In addition, this low dose of GO-Y030 almost completely blocked histone H3K9 acetylation and eliminated left ventricular fibrosis. A low dose of the synthetic curcumin analogue GO-Y030 effectively inhibits p300-HAT activity and markedly suppresses the development of heart failure in mice.

Aortic Banding and Low‐Intensity Exercise Training do not Alter Autophagy in a Yucatan Mini‐Swine Model of Pressure Overload‐Induced Heart Failure

The autophagy‐lysosome system is an essential intracellular proteolytic process mediating recycling of dysfunctional proteins and organelles. This process is important to cellular renovation, and activation of autophagy by exercise training (ET) is considered essential to the maintenance of cellular vitality. However, the implications of chronic low‐intensity ET on autophagic function in an experimental setting of heart failure (HF) remains unclear. The purpose of this study was to determine if autophagy contributes to cardiovascular dysfunction that is treatable by ET in a pre‐clinical model of pressure overload‐induced HF. We hypothesized ET would prevent aortic banding‐induced decreases in autophagy in the heart, coronary vasculature, and skeletal muscle. Male Yucatan mini‐swine (29–32 kg; 8 mo‐old) were assigned to the following groups (6–7 pigs/groups): control (CON), heart failure (HF), heart failure low‐intensity continuous ET (HF‐CT), and heart failure low‐intensity interval ET (HF‐IT). Chronic pressure overload was induced by an aortic band placed on the ascending aorta proximal to the brachiocephalic artery. Two months post‐surgery and after the development of pathological hypertrophic remodeling, animals began treadmill ET 3 times/week at 55 minutes/session for 17 weeks. Autophagic markers measured by protein level of LC3B (a marker of autophagosome formation), p62 (autophagosome cargo receptor) and Beclin 1 (regulation of autophagy initiation), were assessed in the left ventricle (LV), right ventricle (RV), left circumflex artery (LCX), right coronary artery (RCA), deltoid, and long head of the triceps (TLH). We found no changes in autophagic markers (LC3B‐I, LC3B‐II, LC3B‐II/I ratio, p62, and Beclin 1) in LV, RV, LCX, RCA, deltoid, and TLH when comparing HF group with CON group (p&gt;0.05). Similarly, ET of any intensity did not alter autophagic markers in LV, RV, LCX, RCA, deltoid, and TLH compared to CON and HF groups (p&gt;0.05). Contrary to our hypothesis, protein levels of a number of different well‐established markers of autophagy were not decreased in the HF group. Further, our results do not demonstrate any change in this important cellular recycling mechanism following chronic low‐intensity ET. Although activation of autophagy is considered a positive adaptation of ET in a setting of physiological health, these data suggest autophagy may not be a mechanism by which ET of an intensity tolerable to a heart failure patient improves cardiovascular and skeletal muscle health in a pre‐clinical model of pressure overload‐induced HF.Support or Funding InformationCraig A. Emter – NIH/NHLBI R01 HL112998, and Kleiton A. S. Silva – AHA: 18POST33960472

Prevention and rescue of cardiac dysfunction by methanocarba adenosine monophosphonate derivatives.

Accumulating evidence supports a therapeutic role of purinergic signaling in cardiac diseases. Previously, efficacy of systemically infused MRS2339, a charged methanocarba derivative of 2-Cl-adenosine monophosphate, was demonstrated in animal models of heart failure. We now test the hypothesis that an uncharged adenine nucleoside phosphonate, suitable as an oral agent with a hydrolysis-resistant phospho moiety, can prevent the development of cardiac dysfunction in a post-infarction ischemic or pressure overload-induced heart failure model in mice. The diester-masked uncharged phosphonate MRS2978 was efficacious in preventing cardiac dysfunction with improved left ventricular (LV) fractional shortening when administered orally at the onset of ischemic or pressure overload-induced heart failure. MRS2925, the charged, unmasked MRS2978 analog, prevented heart dysfunction when infused subcutaneously but not by oral gavage. When administered orally or systemically, MRS2978 but not MRS2925 could also rescue established cardiac dysfunction in both ischemic and pressure overload heart failure models. The diester-masked phosphate MRS4074 was highly efficacious at preventing the development of dysfunction as well as in rescuing pressure overload-induced and ischemic heart failure. MRS2978 was orally bioavailable (57-75%) giving rise to MRS2925 as a minor metabolite in vivo, tested in rats. The data are consistent with a novel therapeutic role of adenine nucleoside phosphonates in systolic heart failure.

Effects of Lycium barbarum L. Polysaccharides on Inflammation and Oxidative Stress Markers in a Pressure Overload-Induced Heart Failure Rat Model.

Despite recent advances in disease management and prevention, heart failure (HF) prevalence is still high. Hypertension, inflammation and oxidative stress are being investigated as important causative processes in HF. L. barbarum L. polysaccharides (LBPs) are widely used for their anti-inflammatory and antioxidant properties. Thus, the aim of the present study was to evaluate the effects of LBPs on inflammation and oxidative stress markers in a pressure overload-induced HF rat model, surgically induced by abdominal aorta banding in Wistar rats (AAB) (n = 28). Also, control rats (n = 10) were subjected to a sham operation. After echocardiographic confirmation of HF (week 24), AAB rats were divided into three groups: rats treated with LBPs for 12 weeks: 100 mg/kg body weight /day (AAB_100, n = 9), 200 mg/kg body weight /day (AAB_200, n = 7) and no-treatment group (control AAB, n = 12). After 12 weeks of treatment with LBPs, the decline of cardiac function was prevented compared to the control AAB rats. Treatment with 200 mg/kg body weight /day LBPs significantly reduced the inflammation as seen by cytokine levels (IL-6 and TNF-α) and the plasma lipid peroxidation, as seen by malondialdehyde levels. These results suggest that LBPs present anti-inflammatory and antioxidant effects with utility in a HF animal model and encourage further investigation of the cardioprotective effects of these polysaccharides.

Overexpression of mitochondrial creatine kinase preserves cardiac energetics without ameliorating murine chronic heart failure

Mitochondrial creatine kinase (Mt-CK) is a major determinant of cardiac energetic status and is down-regulated in chronic heart failure, which may contribute to disease progression. We hypothesised that cardiomyocyte-specific overexpression of Mt-CK would mitigate against these changes and thereby preserve cardiac function. Male Mt-CK overexpressing mice (OE) and WT littermates were subjected to transverse aortic constriction (TAC) or sham surgery and assessed by echocardiography at 0, 3 and 6 weeks alongside a final LV haemodynamic assessment. Regardless of genotype, TAC mice developed progressive LV hypertrophy, dilatation and contractile dysfunction commensurate with pressure overload-induced chronic heart failure. There was a trend for improved survival in OE-TAC mice (90% vs 73%, P = 0.08), however, OE-TAC mice exhibited greater LV dilatation compared to WT and no functional parameters were significantly different under baseline conditions or during dobutamine stress test. CK activity was 37% higher in OE-sham versus WT-sham hearts and reduced in both TAC groups, but was maintained above normal values in the OE-TAC hearts. A separate cohort of mice received in vivo cardiac 31P-MRS to measure high-energy phosphates. There was no difference in the ratio of phosphocreatine-to-ATP in the sham mice, however, PCr/ATP was reduced in WT-TAC but preserved in OE-TAC (1.04 ± 0.10 vs 2.04 ± 0.22; P = 0.007). In conclusion, overexpression of Mt-CK activity prevented the changes in cardiac energetics that are considered hallmarks of a failing heart. This had a positive effect on early survival but was not associated with improved LV remodelling or function during the development of chronic heart failure.

Endothelial S1pr1 regulates pressure overload-induced cardiac remodelling through AKT-eNOS pathway.

Cardiac vascular microenvironment is crucial for cardiac remodelling during the process of heart failure. Sphingosine 1‐phosphate (S1P) tightly regulates vascular homeostasis via its receptor, S1pr1. We therefore hypothesize that endothelial S1pr1 might be involved in pathological cardiac remodelling. In this study, heart failure was induced by transverse aortic constriction (TAC) operation. S1pr1 expression is significantly increased in microvascular endothelial cells (ECs) of post‐TAC hearts. Endothelial‐specific deletion of S1pr1 significantly aggravated cardiac dysfunction and deteriorated cardiac hypertrophy and fibrosis in myocardium. In vitro experiments demonstrated that S1P/S1pr1 praxis activated AKT/eNOS signalling pathway, leading to more production of nitric oxide (NO), which is an essential cardiac protective factor. Inhibition of AKT/eNOS pathway reversed the inhibitory effect of EC‐S1pr1‐overexpression on angiotensin II (AngII)‐induced cardiomyocyte (CM) hypertrophy, as well as on TGF‐β‐mediated cardiac fibroblast proliferation and transformation towards myofibroblasts. Finally, pharmacological activation of S1pr1 ameliorated TAC‐induced cardiac hypertrophy and fibrosis, leading to an improvement in cardiac function. Together, our results suggest that EC‐S1pr1 might prevent the development of pressure overload‐induced heart failure via AKT/eNOS pathway, and thus pharmacological activation of S1pr1 or EC‐targeting S1pr1‐AKT‐eNOS pathway could provide a future novel therapy to improve cardiac function during heart failure development.