UCP1-dependent brown adipose activation accelerates cardiac metabolic remodeling and reduces initial hypertrophic and fibrotic responses to pathological stress.

Brown adipose tissue (BAT) is correlated to cardiovascular health in rodents and humans, but the physiological role of BAT in the initial cardiac remodeling at the onset of stress is unknown. Activation of BAT via 48 h cold (16°C) in mice following transverse aortic constriction (TAC) reduced cardiac gene expression for LCFA uptake and oxidation in male mice and accelerated the onset of cardiac metabolic remodeling, with an early isoform shift of carnitine palmitoyltransferase 1 (CPT1) toward increased CPT1a, reduced entry of long chain fatty acid (LCFA) into oxidative metabolism (0.59 ± 0.02 vs. 0.72 ± 0.02 in RT TAC hearts, p < .05) and increased carbohydrate oxidation with altered glucose transporter content. BAT activation with TAC reduced early hypertrophic expression of ß-MHC by 61% versus RT-TAC and reduced pro-fibrotic TGF-ß1 and COL3α1 expression. While cardiac natriuretic peptide expression was yet to increase at only 3 days TAC, Nppa and Nppb expression were elevated in Cold TAC versus RT TAC hearts 2.7- and 2.4-fold, respectively. Eliminating BAT thermogenic activation with UCP1 KO mice eliminated differences between Cold TAC and RT TAC hearts, confirming effects of BAT activation rather than autonomous cardiac responses to cold. Female responses to BAT activation were blunted, with limited UCP1 changes with cold, partly due to already activated BAT in females at RT compared to thermoneutrality. These data reveal a previously unknown physiological mechanism of UCP1-dependent BAT activation in attenuating early cardiac hypertrophic and profibrotic signaling and accelerating remodeled metabolic activity in the heart at the onset of cardiac stress.

Resolvin D2/GPR 18 axis ameliorates pressure overload-induced heart failure by inhibiting pro-inflammatory macrophage polarization.

Accumulating evidence has revealed that chronic unresolved inflammation can cause significant tissue damage and can be a key mediator of advanced heart failure (HF). Resolvin (Rv) D2, a member of specialized pro-resolving lipid mediators (SPMs), plays a protective role in various diseases by facilitating resolution. However, whether RvD2 participates in the pathogenesis of HF is still unclear. Our study demonstrated that RvD2 treatment mitigated cardiac remodeling and improved cardiac function in HF mice induced by pressure overload. The absence of G protein-coupled receptor 18 (GPR18), an endogenous receptor for RvD2, abolished the beneficial effects of RvD2 on HF. Additionally, RvD2 inhibited inflammatory responses and Ly6Chigh macrophage polarization during both early and late inflammatory stages involved in HF. Further investigation revealed that bone marrow transplantation from GPR18 deficient mice into WT mice blocked the protective effects of RvD2 in HF mice. Moreover, GPR18 deficiency impeded RvD2's capacity to downregulate inflammatory responses and Ly6Chigh macrophage polarization. Consistent with experiments in vivo, RvD2 treatment in bone marrow-derived macrophages (BMDMs) reduced inflammatory responses through its receptor GPR18. Mechanistically, RvD2 suppressed the phosphorylation of STAT1 and NF-κB p65, and the effects of RvD2 were reversed by the application of STAT1 or NF-κB p65 agonists in BMDMs. In conclusion, RvD2/GPR18 axis improved cardiac remodeling and function in pressure overload-induced HF mice by modulating macrophages phenotype via STAT1 and NF-κB p65 pathways. Our findings underscore the anti-inflammatory potential of RvD2/GPR18 axis, which may be a promising strategy for reducing the burden of HF.

Characteristics of Myocardial Structure and Central Carbon Metabolism during the Early and Compensatory Stages of Cardiac Hypertrophy.

Cardiac hypertrophy is a classical forerunner of heart failure and myocardial structural and metabolic remodeling are closely associated with cardiac hypertrophy. We aim to investigate the characteristics of myocardial structure and central carbon metabolism of cardiac hypertrophy at different stages. Using echocardiography and pathological staining, early and compensatory cardiac hypertrophy were respectively defined as within 7 days and from 7 to 14 days after transverse aortic constriction (TAC) in mice. Among mass-spectrometry-based metabolomics, we identified 45 central carbon metabolites. Differential metabolite analysis showed that six metabolites, including citrate, cis-aconitate and so on, decreased significantly on day 1 after TAC. Ten metabolites, including l-lactate, (S)-2-hydroxyglutarate and so on, were obviously changed on days 10 and 14. Pathway analysis showed that these metabolites were involved in seven metabolic pathways, including carbohydrates, amino acids and so on. Western blot showed the expression of ATP-citrate lyase, malate dehydrogenase 1 and lactate dehydrogenase A in myocardium changed markedly on day 3, while the phosphorylation level of AMP-activated protein kinase did not show significantly difference. We hope our research will promote deeper understanding and early diagnosis of cardiac hypertrophy in clinical practice. All raw data were deposited in MetaboLights (MTBLS10555).

Simple model of pulmonary hypertension secondary to left heart pressure overload induced by partial intravascular occlusion of the ascending aorta.

Pulmonary hypertension is a group of diseases characterized by elevated pulmonary artery pressure and pulmonary vascular resistance with significant morbidity and mortality. The most prevalent type is pulmonary hypertension secondary to left heart disease (PH-LHD). The available experimental models of PH-LHD use partial pulmonary clamping by technically nontrivial open-chest surgery with lengthy recovery. We present a simple model in which the reduction of the cross-sectional area of the ascending aorta is achieved not by external clamping but by partial intravascular obstruction without opening the chest. In anesthetized rats, a blind polyethylene tubing was advanced from the right carotid artery to just above the aortic valve. The procedure is quick and easy to learn. Three weeks after the procedure, left heart pressure overload was confirmed by measuring left ventricular end-diastolic pressure by puncture (1.3 ± 0.2 vs. 0.4 ± 0.3 mmHg in controls, mean ± SD, P < 0.0001). The presence of pulmonary hypertension was documented by measuring pulmonary artery pressure by catheterization (22.3 ± 2.3 vs. 16.9 ± 2.7 mmHg, P = 0.0282) and by detecting right ventricular hypertrophy and increased muscularization of peripheral pulmonary vessels. Contributions of a precapillary vascular segment and vasoconstriction to the increased pulmonary vascular resistance were demonstrated, respectively, by arterial occlusion technique and by normalization of resistance by a vasodilator, sodium nitroprusside, in isolated lungs. These changes were comparable, but not additive, to those induced by an established pulmonary hypertension model, chronic hypoxic exposure. Intravascular partial aortic obstruction offers an easy model of pulmonary hypertension induced by left heart disease that has a vasoconstrictor and precapillary component.NEW & NOTEWORTHY We present a new, simple model of a clinically important type of pulmonary hypertension, that induced by left heart failure. Left ventricular pressure overload is induced in rats by inserting a blinded cannula into the ascending aorta via carotid artery access. This partial intravascular aortic obstruction, which does not require opening of the chest and prolonged recovery, causes pulmonary hypertension, which has a precapillary and vasoconstrictor as well as a vascular remodeling component.

Loss of ADAM15 in female mice does not worsen pressure overload cardiomyopathy, independent of ovarian hormones.

Cardiac hypertrophy is a common feature in several cardiomyopathies. We previously reported that loss of ADAM15 (disintegrin and metalloproteinase 15) worsened cardiac hypertrophy and dilated cardiomyopathy following cardiac pressure overload. Here, we investigated the impact of ADAM15 loss in female mice following cardiac pressure overload induced by transverse aortic constriction (TAC). Female Adam15-/- mice developed the same degree of cardiac hypertrophy, dilation, and dysfunction as the parallel female wild-type (WT) mice at 6 wk post-TAC. To determine if this is due to the protective effects of estrogen, which could mask the negative impact of Adam15 loss, WT and Adam15-/- mice underwent ovariectomy (OVx) 2 wk before TAC. Cardiac structure and function analyses were performed at 6 wk post-TAC. OVx similarly impacted females of both genotypes post-TAC. Calcineurin (Cn) activity was increased post-OVx-TAC, and more in Adam15-/- mice; however, this increase was not reflected in the total-to-phospho-NFAT levels. Integrin-α7 expression, which was upstream of Cn activation in male Adam15-/- -TAC mice, remained unchanged in female mice. However, activation of the mitogen-activated protein kinases (ERK, JNK, P38) was greater in Adam15-/--OVx-TAC than in WT-OVx-TAC mice. In addition, ADAM15 protein levels were significantly increased post-TAC in male but not in female WT mice. Myocardial fibrosis was comparable in non-OVx WT-TAC and Adam15-/- -TAC mice. OVx increased the perivascular fibrosis more in Adam15-/- compared with WT mice post-TAC. Our data demonstrate that loss of ovarian hormones did not fully replicate the male phenotype in the female Adam15-/- mice post-TAC. As ADAM15 levels were increased in males but not in females post-TAC, it is plausible that ADAM15 does not play a prominent role in post-TAC events in female mice. Our findings highlight the significance of factors other than sex hormones in mediating cardiomyopathies in females, which require a more thorough understanding.NEW & NOTEWORTHY Loss of ADAM15 in female mice, unlike the male mice, does not worsen the cardiomyopathy following cardiac pressure overload. Ovariectomy does not worsen the post-TAC cardiomyopathy in female Adam15-/- mice compared with female WT mice. Lack of deleterious impact of Adam15 deficiency in female mice is not because of the protective effects of ovarian hormones but could be due to a less prominent role of ADAM15 in cardiac response to post-TAC remodeling in female mice.

Cardiac fibroblasts: answering the call.

Cardiac fibroblasts play a pivotal role in maintaining heart homeostasis by depositing extracellular matrix (ECM) to provide structural support for the myocardium, vasculature, and neuronal network and by contributing to essential physiological processes. In response to injury such as myocardial infarction or pressure overload, fibroblasts become activated, leading to increased ECM production that can ultimately drive left ventricular remodeling and progress to heart failure. Recently, the American Journal of Physiology-Heart and Circulatory Physiology issued a call for papers on cardiac fibroblasts that yielded articles with topics spanning fibroblast physiology, technical considerations, signaling pathways, and interactions with other cell types. This mini-review summarizes those articles and places the new findings in the context of what is currently known for cardiac fibroblasts and what future directions remain.

Fibroblasts under pressure: cardiac fibroblast responses to hypertension and antihypertensive therapies.

Approximately 50% of Americans have hypertension, which significantly increases the risk of heart failure. In response to increased peripheral resistance in hypertension, intensified mechanical stretch in the myocardium induces cardiomyocyte hypertrophy and fibroblast activation to withstand increased pressure overload. This changes the structure and function of the heart, leading to pathological cardiac remodeling and eventual progression to heart failure. In the presence of hypertensive stimuli, cardiac fibroblasts activate and differentiate to myofibroblast phenotype capable of enhanced extracellular matrix secretion in coordination with other cell types, mainly cardiomyocytes. Both systemic and local renin-angiotensin-aldosterone system activation lead to increased angiotensin II stimulation of fibroblasts. Angiotensin II directly activates fibrotic signaling such as transforming growth factor ß/SMAD and mitogen-activated protein kinase (MAPK) signaling to produce extracellular matrix comprised of collagens and matricellular proteins. With the advent of single-cell RNA sequencing techniques, heterogeneity in fibroblast populations has been identified in the left ventricle in models of hypertension and pressure overload. The various clusters of fibroblasts reveal a range of phenotypes and activation states. Select antihypertensive therapies have been shown to be effective in limiting fibrosis, with some having direct actions on cardiac fibroblasts. The present review focuses on the fibroblast-specific changes that occur in response to hypertension and pressure overload, the knowledge gained from single-cell analyses, and the effect of antihypertensive therapies. Understanding the dynamics of hypertensive fibroblast populations and their similarities and differences by sex is crucial for the advent of new targets and personalized medicine.

Disruption of the interaction between caveolae and Piezo1 promotes pressure overload-induced cardiac remodeling.

Piezo1 channels are activated by mechanical stress and play a significant role in cardiac hypertrophy and fibrosis. However, the molecular mechanisms underlying Piezo1 activation on the cell membrane following pressure overload remain unclear. Caveolae are known to mitigate mechanical forces and regulate Piezo1 function. Therefore, this study aimed to investigate the interaction between caveolae and Piezo1 in the development of pressure overload-induced cardiac remodeling. We observed reduced colocalization between Piezo1 and Caveolin-3 in hypertrophic cardiomyocytes following abdominal aortic constriction and Angiotensin-II treatment, accompanied by increased Piezo1 function and expression. Furthermore, enhanced Piezo1 function was also noted upon caveolae disruption using methyl-beta-cyclodextrin (mßCD). Thus, our findings suggested that pressure overload led to Piezo1 translocation from caveolae, thereby augmenting its function and expression, which may contribute to cardiac remodeling.

CEAM is a mitochondrial-localized, amyloid-like motif-containing microprotein expressed in human cardiomyocytes.

Microproteins synthesized through non-canonical translation pathways are frequently found within mitochondria. However, the functional significance of these mitochondria-localized microproteins in energy-intensive organs such as the heart remains largely unexplored. In this study, we demonstrate that the long non-coding RNA CD63-AS1 encodes a mitochondrial microprotein. Notably, in ribosome profiling data of human hearts, there is a positive correlation between the expression of CD63-AS1 and genes associated with cardiomyopathy. We have termed this microprotein CEAM (CD63-AS1 encoded amyloid-like motif containing microprotein), reflecting its sequence characteristics. Our biochemical assays show that CEAM forms protease-resistant aggregates within mitochondria, whereas deletion of the amyloid-like motif transforms CEAM into a soluble cytosolic protein. Overexpression of CEAM triggers mitochondrial stress responses and adversely affect mitochondrial bioenergetics in cultured cardiomyocytes. In turn, the expression of CEAM is reciprocally inhibited by the activation of mitochondrial stresses induced by oligomycin. When expressed in mouse hearts via adeno-associated virus, CEAM impairs cardiac function. However, under conditions of pressure overload-induced cardiac hypertrophy, CEAM expression appears to offer a protective benefit and mitigates the expression of genes associated with cardiac remodeling, presumably through a mechanism that suppresses stress-induced translation reprogramming. Collectively, our study uncovers a hitherto unexplored amyloid-like microprotein expressed in the human cardiomyocytes, offering novel insights into myocardial hypertrophy pathophysiology.

Fibrosis and expression of extracellular matrix proteins in human interventricular septum in aortic valve stenosis and regurgitation.

Valvular heart disease leads to ventricular pressure and/or volume overload. Pressure overload leads to fibrosis, which might regress with its resolution, but the limits and details of this reverse remodeling are not known. To gain more insight into the extent and nature of cardiac fibrosis in valve disease, we analyzed needle biopsies taken from the interventricular septum of patients undergoing surgery for valve replacement focusing on the expression and distribution of major extracellular matrix protein involved in this process. Proteomic analysis performed using mass spectrometry revealed an excellent correlation between the expression of collagen type I and III, but there was little correlation with the immunohistochemical staining performed on sister sections, which included antibodies against collagen I, III, fibronectin, sarcomeric actin, and histochemistry for wheat germ agglutinin. Surprisingly, the immunofluorescence intensity did not correlate significantly with the gold standard for fibrosis quantification, which was performed using Picrosirius Red (PSR) staining, unless multiplexed on the same tissue section. There was also little correlation between the immunohistochemical markers and pressure gradient severity. It appears that at least in humans, the immunohistochemical pattern of fibrosis is not clearly correlated with standard Picrosirius Red staining on sister sections or quantitative proteomic data, possibly due to tissue heterogeneity at microscale, comorbidities, or other patient-specific factors. For precise correlation of different types of staining, multiplexing on the same section is the best approach.

Large animal models to study effectiveness of therapy devices in the treatment of heart failure with preserved ejection fraction (HFpEF).

Our understanding of the complex pathophysiology of Heart failure with preserved ejection fraction (HFpEF) is limited by the lack of a robust in vivo model. Existing in-vivo models attempt to reproduce the four main phenotypes of HFpEF; ageing, obesity, diabetes mellitus and hypertension. To date, there is no in vivo model that represents all the haemodynamic characteristics of HFpEF, and only a few have proven to be reliable for the preclinical evaluation of potentially new therapeutic targets. HFpEF accounts for 50% of all the heart failure cases and its incidence is on the rise, posing a huge economic burden on the health system. Patients with HFpEF have limited therapeutic options available. The inadequate effectiveness of current pharmaceutical therapeutics for HFpEF has prompted the development of device-based treatments that target the hemodynamic changes to reduce the symptoms of HFpEF. However, despite the potential of device-based solutions to treat HFpEF, most of these therapies are still in the developmental stage and a relevant HFpEF in vivo model will surely expedite their development process. This review article outlines the major limitations of the current large in-vivo models in use while discussing how these designs have helped in the development of therapy devices for the treatment of HFpEF.

Myocardial transcriptomic analysis of diabetic patients with aortic stenosis: key role for mitochondrial calcium signaling.

BACKGROUND: Type 2 diabetes (T2D) is a frequent comorbidity encountered in patients with severe aortic stenosis (AS), leading to an adverse left ventricular (LV) remodeling and dysfunction. Metabolic alterations have been suggested as contributors of the deleterious effect of T2D on LV remodeling and function in patients with severe AS, but so far, the underlying mechanisms remain unclear. Mitochondria play a central role in the regulation of cardiac energy metabolism. OBJECTIVES: We aimed to explore the mitochondrial alterations associated with the deleterious effect of T2D on LV remodeling and function in patients with AS, preserved ejection fraction, and no additional heart disease. METHODS: We combined an in-depth clinical, biological and echocardiography phenotype of patients with severe AS, with (n = 34) or without (n = 50) T2D, referred for a valve replacement, with transcriptomic and histological analyses of an intra-operative myocardial LV biopsy. RESULTS: T2D patients had similar AS severity but displayed worse cardiac remodeling, systolic and diastolic function than non-diabetics. RNAseq analysis identified 1029 significantly differentially expressed genes. Functional enrichment analysis revealed several T2D-specific upregulated pathways despite comorbidity adjustment, gathering regulation of inflammation, extracellular matrix organization, endothelial function/angiogenesis, and adaptation to cardiac hypertrophy. Downregulated gene sets independently associated with T2D were related to mitochondrial respiratory chain organization/function and mitochondrial organization. Generation of causal networks suggested a reduced Ca2+ signaling up to the mitochondria, with the measured gene remodeling of the mitochondrial Ca2+ uniporter in favor of enhanced uptake. Histological analyses supported a greater cardiomyocyte hypertrophy and a decreased proximity between the mitochondrial VDAC porin and the reticular IP3-receptor in T2D. CONCLUSIONS: Our data support a crucial role for mitochondrial Ca2+ signaling in T2D-induced cardiac dysfunction in severe AS patients, from a structural reticulum-mitochondria Ca2+ uncoupling to a mitochondrial gene remodeling. Thus, our findings open a new therapeutic avenue to be tested in animal models and further human cardiac biopsies in order to propose new treatments for T2D patients suffering from AS. TRIAL REGISTRATION: URL: https://www. CLINICALTRIALS: gov ; Unique Identifier: NCT01862237.

SAA1 deficiency alleviates cardiac remodeling by inhibiting NF-κB/p38/JNK and TGFß/Smad pathways.

Heart failure (HF) is the end stage of the progression of many cardiovascular diseases. Cardiac remodeling is the main pathophysiological process of cardiac function deterioration in HF patients. Inflammation is a key factor that stimulates cardiomyocyte hypertrophy, fibroblast proliferation, and transformation leading to myocardial remodeling, which severity is significantly related to the prognosis of patients. SAA1 (Serum amyloid A1) is a lipid-binding protein that was an important regulator involved in inflammation, whose biological functions in the heart remain rarely known. In this research, we intended to test the role of SAA1 in SAA1-deficient (SAA1-/- ), and wild-type mice were exposed to transverse aortic banding surgery to establish the model of cardiac remodeling. Besides, we assessed the functional effects of SAA1 on cardiac hypertrophy and fibrosis. The expression of SAA1 was increased in the mice transverse aortic banding model induced by pressure overload. After 8 weeks of transverse aortic banding, SAA1-/- mice displayed a lower level of cardiac fibrosis than wild-type mice, but did not significantly influence the cardiomyocyte hypertrophy. In addition, there was also no significant difference in cardiac fibrosis severity between wild-type-sham and knockout-sham mice. These findings are the first to reveal SAA1 absence hinders cardiac fibrosis after 8 weeks of transverse aortic banding. Furthermore, SAA1 deficiency had no significant effect on cardiac fibrosis and hypertrophy in the sham group in this study.

Gene expression profiles, potential targets and treatments of cardiac remodeling.

Hypertensive and ischemic heart diseases have high morbidity all over the world, and they primarily contribute to heart failure associated with high mortality. Cardiac remodeling, as a basic pathological process in heart diseases, is mainly comprised of cardiac hypertrophy and fibrosis, as well as cell death which occurs especially in the ischemic cardiomyopathy. Myocardial remodeling has been widely investigated by a variety of animal models, including pressure overload, angiotensin II stimulation, and myocardial infarction. Pressure overload can cause compensatory cardiac hypertrophy at the early stage, followed by decompensatory hypertrophy and heart failure at the end. Recently, RNA sequencing and differentially expressed gene (DEG) analyses have been extensively employed to elucidate the molecular mechanisms of cardiac remodeling and related heart failure, which also provide potential targets for high-throughput drug screenings. In this review, we summarize recent advancements in gene expression profiling, related gene functions, and signaling pathways pertinent to myocardial remodeling induced by pressure overload at distinct stages, ischemia-reperfusion, myocardial infarction, and diabetes. We also discuss the effects of sex differences and inflammation on DEGs and their transcriptional regulatory mechanisms in cardiac remodeling. Additionally, we summarize emerging therapeutic agents and strategies aimed at modulating gene expression profiles during myocardial remodeling.

Effects of hemodynamic load on cardiac remodeling in fish and mammals: the value of comparative models.

The ability of the vertebrate heart to remodel enables the cardiac phenotype to be responsive to changes in physiological conditions and aerobic demand. Examples include exercise-induced cardiac hypertrophy, and the significant remodeling of the trout heart during thermal acclimation. Such changes are thought to occur in response to a change in hemodynamic load (i.e. the forces that the heart must work against to circulate blood). Variations in hemodynamic load are caused by either a volume overload (high volume of blood returning to the heart, impairing contraction) or a pressure overload (elevated afterload pressure that the heart must contract against). The changes observed in the heart during remodeling are regulated by multiple cellular signaling pathways. The cardiac response to these regulatory mechanisms occurs across levels of biological organization, affecting cardiac morphology, tissue composition and contractile function. Importantly, prolonged exposure to pressure overload can cause a physiological response - that improves function - to transition to a pathological response that causes loss of function. This Review explores the role of changes in hemodynamic load in regulating the remodeling response, and considers the cellular signals responsible for regulating remodeling, incorporating knowledge gained from studying biomedical models and comparative animal models. We specifically focus on the renin-angiotensin system, and the role of nitric oxide, oxygen free radicals and transforming growth factor beta. Through this approach, we highlight the strong conservation of the regulatory pathways of cardiac remodeling, and the specific conditions within endotherms that may be conducive to the development of pathological phenotypes.

Sphingosylphosphorylcholine alleviates pressure overload-induced myocardial remodeling in mice via inhibiting CaM-JNK/p38 signaling pathway.

Apoptosis plays a critical role in the development of heart failure, and sphingosylphosphorylcholine (SPC) is a bioactive sphingolipid naturally occurring in blood plasma. Some studies have shown that SPC inhibits hypoxia-induced apoptosis in myofibroblasts, the crucial non-muscle cells in the heart. Calmodulin (CaM) is a known SPC receptor. In this study we investigated the role of CaM in cardiomyocyte apoptosis in heart failure and the associated signaling pathways. Pressure overload was induced in mice by trans-aortic constriction (TAC) surgery. TAC mice were administered SPC (10 µM·kg-1·d-1) for 4 weeks post-surgery. We showed that SPC administration significantly improved survival rate and cardiac hypertrophy, and inhibited cardiac fibrosis in TAC mice. In neonatal mouse cardiomyocytes, treatment with SPC (10 µM) significantly inhibited Ang II-induced cardiomyocyte hypertrophy, fibroblast-to-myofibroblast transition and cell apoptosis accompanied by reduced Bax and phosphorylation levels of CaM, JNK and p38, as well as upregulated Bcl-2, a cardiomyocyte-protective protein. Thapsigargin (TG) could enhance CaM functions by increasing Ca2+ levels in cytoplasm. TG (3 µM) annulled the protective effect of SPC against Ang II-induced cardiomyocyte apoptosis. Furthermore, we demonstrated that SPC-mediated inhibition of cardiomyocyte apoptosis involved the regulation of p38 and JNK phosphorylation, which was downstream of CaM. These results offer new evidence for SPC regulation of cardiomyocyte apoptosis, potentially providing a new therapeutic target for cardiac remodeling following stress overload.

Zonisamide attenuates pressure overload-induced myocardial hypertrophy in mice through proteasome inhibition.

Myocardial hypertrophy is a pathological thickening of the myocardium which ultimately results in heart failure. We previously reported that zonisamide, an antiepileptic drug, attenuated pressure overload-caused myocardial hypertrophy and diabetic cardiomyopathy in murine models. In addition, we have found that the inhibition of proteasome activates glycogen synthesis kinase 3 (GSK-3) thus alleviates myocardial hypertrophy, which is an important anti-hypertrophic strategy. In this study, we investigated whether zonisamide prevented pressure overload-caused myocardial hypertrophy through suppressing proteasome. Pressure overload-caused myocardial hypertrophy was induced in mice by trans-aortic constriction (TAC) surgery. Two days after the surgery, the mice were administered zonisamide (10, 20, 40 mg·kg-1·d-1, i.g.) for four weeks. We showed that zonisamide administration significantly mitigated impaired cardiac function. Furthermore, zonisamide administration significantly inhibited proteasome activity as well as the expression levels of proteasome subunit beta types (PSMB) of the 20 S proteasome (PSMB1, PSMB2 and PSMB5) and proteasome-regulated particles (RPT) of the 19 S proteasome (RPT1, RPT4) in heart tissues of TAC mice. In primary neonatal rat cardiomyocytes (NRCMs), zonisamide (0.3 µM) prevented myocardial hypertrophy triggered by angiotensin II (Ang II), and significantly inhibited proteasome activity, proteasome subunits and proteasome-regulated particles. In Ang II-treated NRCMs, we found that 18α-glycyrrhetinic acid (18α-GA, 2 mg/ml), a proteasome inducer, eliminated the protective effects of zonisamide against myocardial hypertrophy and proteasome. Moreover, zonisamide treatment activated GSK-3 through inhibiting the phosphorylated AKT (protein kinase B, PKB) and phosphorylated liver kinase B1/AMP-activated protein kinase (LKB1/AMPKα), the upstream of GSK-3. Zonisamide treatment also inhibited GSK-3's downstream signaling proteins, including extracellular signal-regulated kinase (ERK) and GATA binding protein 4 (GATA4), both being the hypertrophic factors. Collectively, this study highlights the potential of zonisamide as a new therapeutic agent for myocardial hypertrophy, as it shows potent anti-hypertrophic potential through the suppression of proteasome.

Hemodynamics During Development and Postnatal Life.

A well-developed heart is essential for embryonic survival. There are constant interactions between cardiac tissue motion and blood flow, which determine the heart shape itself. Hemodynamic forces are a powerful stimulus for cardiac growth and differentiation. Therefore, it is particularly interesting to investigate how the blood flows through the heart and how hemodynamics is linked to a particular species and its development, including human. The appropriate patterns and magnitude of hemodynamic stresses are necessary for the proper formation of cardiac structures, and hemodynamic perturbations have been found to cause malformations via identifiable mechanobiological molecular pathways. There are significant differences in cardiac hemodynamics among vertebrate species, which go hand in hand with the presence of specific anatomical structures. However, strong similarities during development suggest a common pattern for cardiac hemodynamics in human adults. In the human fetal heart, hemodynamic abnormalities during gestation are known to progress to congenital heart malformations by birth. In this chapter, we discuss the current state of the knowledge of the prenatal cardiac hemodynamics, as discovered through small and large animal models, as well as from clinical investigations, with parallels gathered from the poikilotherm vertebrates that emulate some hemodynamically significant human congenital heart diseases.

Anserine, a Histidine-Containing Dipeptide, Suppresses Pressure Overload-Induced Systolic Dysfunction by Inhibiting Histone Acetyltransferase Activity of p300 in Mice.

Anserine, an imidazole dipeptide, is present in the muscles of birds and fish and has various bioactivities, such as anti-inflammatory and anti-fatigue effects. However, the effect of anserine on the development of heart failure remains unknown. We cultured primary cardiomyocytes with 0.03 mM to 10 mM anserine and stimulated them with phenylephrine for 48 h. Anserine significantly suppressed the phenylephrine-induced increases in cardiomyocyte hypertrophy, ANF and BNP mRNA levels, and histone H3K9 acetylation. An in vitro histone acetyltransferase (HAT) assay showed that anserine directly suppressed p300-HAT activity with an IC50 of 1.87 mM. Subsequently, 8-week-old male C57BL/6J mice were subjected to transverse aortic constriction (TAC) and were randomly assigned to receive daily oral treatment with anserine-containing material, Marine Active® (60 or 200 mg/kg anserine) or vehicle for 8 weeks. Echocardiography revealed that anserine 200 mg/kg significantly prevented the TAC-induced increase in left ventricular posterior wall thickness and the decrease in left ventricular fractional shortening. Moreover, anserine significantly suppressed the TAC-induced acetylation of histone H3K9. These results indicate that anserine suppresses TAC-induced systolic dysfunction, at least in part, by inhibiting p300-HAT activity. Anserine may be used as a pharmacological agent for human heart failure therapy.

Suppression of myeloid YAP antagonizes adverse cardiac remodeling during pressure overload stress.

Inflammation is an integral component of cardiovascular disease and is thought to contribute to cardiac dysfunction and heart failure. While ischemia-induced inflammation has been extensively studied in the heart, relatively less is known regarding cardiac inflammation during non-ischemic stress. Recent work has implicated a role for Yes-associated protein (YAP) in modulating inflammation in response to ischemic injury; however, whether YAP influences inflammation in the heart during non-ischemic stress is not described. We hypothesized that YAP mediates a pro-inflammatory response during pressure overload (PO)-induced non-ischemic injury, and that targeted YAP inhibition in the myeloid compartment is cardioprotective. In mice, PO elicited myeloid YAP activation, and myeloid-specific YAP knockout mice (YAPF/F;LysMCre) subjected to PO stress had better systolic function, and attenuated pathological remodeling compared to control mice. Inflammatory indicators were also significantly attenuated, while pro-resolving genes including Vegfa were enhanced, in the myocardium, and in isolated macrophages, of myeloid YAP KO mice after PO. Experiments using bone marrow-derived macrophages (BMDMs) from YAP KO and control mice demonstrated that YAP suppression shifted polarization toward a resolving phenotype. We also observed attenuated NLRP3 inflammasome priming and function in YAP deficient BMDMs, as well as in myeloid YAP KO hearts following PO, indicating disruption of inflammasome induction. Finally, we leveraged nanoparticle-mediated delivery of the YAP inhibitor verteporfin and observed attenuated PO-induced pathological remodeling compared to DMSO nanoparticle control treatment. These data implicate myeloid YAP as an important molecular nodal point that facilitates cardiac inflammation and fibrosis during PO stress and suggest that selective inhibition of YAP may prove a novel therapeutic target in non-ischemic heart disease.