Large animal models of pressure overload-induced cardiac left ventricular hypertrophy to study remodelling of the human heart with aortic stenosis.

Pathologic cardiac hypertrophy is a common consequence of many cardiovascular diseases, including aortic stenosis (AS). AS is known to increase the pressure load of the left ventricle, causing a compensative response of the cardiac muscle, which progressively will lead to dilation and heart failure. At a cellular level, this corresponds to a considerable increase in the size of cardiomyocytes, known as cardiomyocyte hypertrophy, while their proliferation capacity is attenuated upon the first developmental stages. Cardiomyocytes, in order to cope with the increased workload (overload), suffer alterations in their morphology, nuclear content, energy metabolism, intracellular homeostatic mechanisms, contractile activity, and cell death mechanisms. Moreover, modifications in the cardiomyocyte niche, involving inflammation, immune infiltration, fibrosis, and angiogenesis, contribute to the subsequent events of a pathologic hypertrophic response. Considering the emerging need for a better understanding of the condition and treatment improvement, as the only available treatment option of AS consists of surgical interventions at a late stage of the disease, when the cardiac muscle state is irreversible, large animal models have been developed to mimic the human condition, to the greatest extend. Smaller animal models lack physiological, cellular and molecular mechanisms that sufficiently resemblance humans and in vitro techniques yet fail to provide adequate complexity. Animals, such as the ferret (Mustello purtorius furo), lapine (rabbit, Oryctolagus cunigulus), feline (cat, Felis catus), canine (dog, Canis lupus familiaris), ovine (sheep, Ovis aries), and porcine (pig, Sus scrofa), have contributed to research by elucidating implicated cellular and molecular mechanisms of the condition. Essential discoveries of each model are reported and discussed briefly in this review. Results of large animal experimentation could further be interpreted aiming at prevention of the disease progress or, alternatively, at regression of the implicated pathologic mechanisms to a physiologic state. This review summarizes the important aspects of the pathophysiology of LV hypertrophy and the applied surgical large animal models that currently better mimic the condition.

Stromal Cell-SLIT3/Cardiomyocyte-ROBO1 Axis Regulates Pressure Overload-Induced Cardiac Hypertrophy.

BACKGROUND: Recently shown to regulate cardiac development, the secreted axon guidance molecule SLIT3 maintains its expression in the postnatal heart. Despite its known expression in the cardiovascular system after birth, SLIT3's relevance to cardiovascular function in the postnatal state remains unknown. As such, the objectives of this study were to determine the postnatal myocardial sources of SLIT3 and to evaluate its functional role in regulating the cardiac response to pressure overload stress. METHODS: We performed in vitro studies on cardiomyocytes and myocardial tissue samples from patients and performed in vivo investigation with SLIT3 and ROBO1 (roundabout homolog 1) mutant mice undergoing transverse aortic constriction to establish the role of SLIT3-ROBO1 in adverse cardiac remodeling. RESULTS: We first found that SLIT3 transcription was increased in myocardial tissue obtained from patients with congenital heart defects that caused ventricular pressure overload. Immunostaining of hearts from WT (wild-type) and reporter mice revealed that SLIT3 is secreted by cardiac stromal cells, namely fibroblasts and vascular mural cells, within the heart. Conditioned media from cardiac fibroblasts and vascular mural cells both stimulated cardiomyocyte hypertrophy in vitro, an effect that was partially inhibited by an anti-SLIT3 antibody. Also, the N-terminal, but not the C-terminal, fragment of SLIT3 and the forced overexpression of SLIT3 stimulated cardiomyocyte hypertrophy and the transcription of hypertrophy-related genes. We next determined that ROBO1 was the most highly expressed roundabout receptor in cardiomyocytes and that ROBO1 mediated SLIT3's hypertrophic effects in vitro. In vivo, Tcf21+ fibroblast and Tbx18+ vascular mural cell-specific knockout of SLIT3 in mice resulted in decreased left ventricular hypertrophy and cardiac fibrosis after transverse aortic constriction. Furthermore, α-MHC+ cardiomyocyte-specific deletion of ROBO1 also preserved left ventricular function and abrogated hypertrophy, but not fibrosis, after transverse aortic constriction. CONCLUSIONS: Collectively, these results indicate a novel role for the SLIT3-ROBO1-signaling axis in regulating postnatal cardiomyocyte hypertrophy induced by pressure overload.

Role of Cardiac Energetics in Aortic Stenosis Disease Progression: Identifying the High-risk Metabolic Phenotype.

BACKGROUND: Severe aortic stenosis (AS) is associated with left ventricular (LV) hypertrophy and cardiac metabolic alterations with evidence of steatosis and impaired myocardial energetics. Despite this common phenotype, there is an unexplained and wide individual heterogeneity in the degree of hypertrophy and progression to myocardial fibrosis and heart failure. We sought to determine whether the cardiac metabolic state may underpin this variability. METHODS: We recruited 74 asymptomatic participants with AS and 13 healthy volunteers. Cardiac energetics were measured using phosphorus spectroscopy to define the myocardial phosphocreatine to adenosine triphosphate ratio. Myocardial lipid content was determined using proton spectroscopy. Cardiac function was assessed by cardiovascular magnetic resonance cine imaging. RESULTS: Phosphocreatine/adenosine triphosphate was reduced early and significantly across the LV wall thickness quartiles (Q2, 1.50 [1.21-1.71] versus Q1, 1.64 [1.53-1.94]) with a progressive decline with increasing disease severity (Q4, 1.48 [1.18-1.70]; P=0.02). Myocardial triglyceride content levels were overall higher in all the quartiles with a significant increase seen across the AV pressure gradient quartiles (Q2, 1.36 [0.86-1.98] versus Q1, 1.03 [0.81-1.56]; P=0.034). While all AS groups had evidence of subclinical LV dysfunction with impaired strain parameters, impaired systolic longitudinal strain was related to the degree of energetic impairment (r=0.219; P=0.03). Phosphocreatine/adenosine triphosphate was not only an independent predictor of LV wall thickness (r=-0.20; P=0.04) but also strongly associated with myocardial fibrosis (r=-0.24; P=0.03), suggesting that metabolic changes play a role in disease progression. The metabolic and functional parameters showed comparable results when graded by clinical severity of AS. CONCLUSIONS: A gradient of myocardial energetic deficit and steatosis exists across the spectrum of hypertrophied AS hearts, and these metabolic changes precede irreversible LV remodeling and subclinical dysfunction. As such, cardiac metabolism may play an important and potentially causal role in disease progression.

Deletion of Endothelial TRPV4 Protects Heart From Pressure Overload-Induced Hypertrophy.

BACKGROUND: Left ventricular hypertrophy is a bipolar response, starting as an adaptive response to the hemodynamic challenge, but over time develops maladaptive pathology partly due to microvascular rarefaction and impaired coronary angiogenesis. Despite the profound influence on cardiac function, the mechanotransduction mechanisms that regulate coronary angiogenesis, leading to heart failure, are not well known. METHODS: We subjected endothelial-specific knockout mice of mechanically activated ion channel, TRPV4 (transient receptor potential cation channel subfamily V member 4; TRPV4ECKO) to pressure overload via transverse aortic constriction and examined cardiac function, cardiomyocyte hypertrophy, cardiac fibrosis, and apoptosis. Further, we measured microvascular density and underlying TRPV4 mechanotransduction mechanisms using human microvascular endothelial cells, extracellular matrix gels of varying stiffness, unbiased RNA sequencing, small interfering RNA, Western blot, quantitative-PCR, and confocal immunofluorescence techniques. RESULTS: We demonstrate that endothelial-specific deletion of TRPV4 preserved cardiac function, cardiomyocyte structure, and reduced cardiac fibrosis compared with TRPV4lox/lox mice, 28 days post-transverse aortic constriction. Interestingly, comprehensive RNA sequencing analysis revealed an upregulation of proangiogenic factors (VEGFα [vascular endothelial growth factor α], NOS3 [nitric oxide synthase 3], and FGF2 [fibroblast growth factor 2]) with concomitant increase in microvascular density in TRPV4ECKO hearts after transverse aortic constriction compared with TRPV4lox/lox. Further, an increased expression of VEGFR2 (vascular endothelial growth factor receptor 2) and activation of the YAP (yes-associated protein) pathway were observed in TRPV4ECKO hearts. Mechanistically, we found that downregulation of TRPV4 in endothelial cells induced matrix stiffness-dependent activation of YAP and VEGFR2 via the Rho/Rho kinase/large tumor suppressor kinase pathway. CONCLUSIONS: Our results suggest that endothelial TRPV4 acts as a mechanical break for coronary angiogenesis, and uncoupling endothelial TRPV4 mechanotransduction attenuates pathological cardiac hypertrophy by enhancing coronary angiogenesis.

[The role of inflammation in heart failure with preserved ejection fraction].

Heart failure with preserved ejection fraction (HFpEF) is a type of heart failure characterized by left ventricular diastolic dysfunction with preserved ejection fraction. With the aging of the population and the increasing prevalence of metabolic diseases, such as hypertension, obesity and diabetes, the prevalence of HFpEF is increasing. Compared with heart failure with reduced ejection fraction (HFrEF), conventional anti-heart failure drugs failed to reduce the mortality in HFpEF due to the complex pathophysiological mechanism and multiple comorbidities of HFpEF. It is known that the main changes of cardiac structure of in HFpEF are cardiac hypertrophy, myocardial fibrosis and left ventricular hypertrophy, and HFpEF is commonly associated with obesity, diabetes, hypertension, renal dysfunction and other diseases, but how these comorbidities cause structural and functional damage to the heart is not completely clear. Recent studies have shown that immune inflammatory response plays a vital role in the progression of HFpEF. This review focuses on the latest research progress in the role of inflammation in the process of HFpEF and the potential application of anti-inflammatory therapy in HFpEF, hoping to provide new research ideas and theoretical basis for the clinical prevention and treatment in HFpEF.

Bioinformatics exploration of potential common therapeutic targets for systemic and pulmonary arterial hypertension-induced myocardial hypertrophy.

Systemic and pulmonary arterial hypertension (PAH) can induce left and right ventricular hypertrophy, respectively, but common therapeutic targets for both left and right hypertrophy are limited. In this study, we attempt to explore potential common therapeutic targets and screen out potential target drugs for further study. Cardiac mRNA expression profiles in mice with transverse aortic constriction (TAC) and pulmonary arterial constriction (PAC) are obtained from online databases. After bioinformatics analyses, we generate TAC and PAC mouse models to validate the phenotypes of cardiac remodelling as well as the identified hub genes. Bioinformatics analyses show that there are 214 independent differentially expressed genes (DEGs) in GSE136308 (TAC related) and 2607 independent DEGs in GSE30922 (PAC related), while 547 shared DEGs are associated with the function of the extracellular matrix (ECM) or involved in the PI3K-Akt signaling pathway, cytokine-cytokine receptor interactions, and ECM-receptor interactions. We identifyd Fn1, Il6, Col1a1, Igf1, Col1a2, Timp1, Col3a1, Cd44, Ctgf and Postn as hub genes of the shared DEGs, and most of them are associated with myocardial fibrosis. Those hub genes and phenotypes of cardiac remodelling are validated in our TAC and PAC mouse models. Furthermore, we identify dehydroisoandrosterone (DHEA), iloprost and 4,5-dianilinophthalimide (DAPH) as potential therapeutic drugs targeting both left and right ventricular hypertrophy and validate the effect of DHEA. These findings suggest that DHEA could be an effective drug for pressure overload-induced left or right ventricular hypertrophy by regulating the shared hub differentially expressed genes associated with fibrosis.

The role of inflammation in heart failure with preserved ejection fraction / 生理学报

Heart failure with preserved ejection fraction (HFpEF) is a type of heart failure characterized by left ventricular diastolic dysfunction with preserved ejection fraction. With the aging of the population and the increasing prevalence of metabolic diseases, such as hypertension, obesity and diabetes, the prevalence of HFpEF is increasing. Compared with heart failure with reduced ejection fraction (HFrEF), conventional anti-heart failure drugs failed to reduce the mortality in HFpEF due to the complex pathophysiological mechanism and multiple comorbidities of HFpEF. It is known that the main changes of cardiac structure of in HFpEF are cardiac hypertrophy, myocardial fibrosis and left ventricular hypertrophy, and HFpEF is commonly associated with obesity, diabetes, hypertension, renal dysfunction and other diseases, but how these comorbidities cause structural and functional damage to the heart is not completely clear. Recent studies have shown that immune inflammatory response plays a vital role in the progression of HFpEF. This review focuses on the latest research progress in the role of inflammation in the process of HFpEF and the potential application of anti-inflammatory therapy in HFpEF, hoping to provide new research ideas and theoretical basis for the clinical prevention and treatment in HFpEF.

Alterations of Lipid Metabolism in the Heart in Spontaneously Hypertensive Rats Precedes Left Ventricular Hypertrophy and Cardiac Dysfunction.

Disturbances in cardiac lipid metabolism are associated with the development of cardiac hypertrophy and heart failure. Spontaneously hypertensive rats (SHRs), a genetic model of primary hypertension and pathological left ventricular (LV) hypertrophy, have high levels of diacylglycerols in cardiomyocytes early in development. However, the exact effect of lipids and pathways that are involved in their metabolism on the development of cardiac dysfunction in SHRs is unknown. Therefore, we used SHRs and Wistar Kyoto (WKY) rats at 6 and 18 weeks of age to analyze the impact of perturbations of processes that are involved in lipid synthesis and degradation in the development of LV hypertrophy in SHRs with age. Triglyceride levels were higher, whereas free fatty acid (FA) content was lower in the LV in SHRs compared with WKY rats. The expression of de novo FA synthesis proteins was lower in cardiomyocytes in SHRs compared with corresponding WKY controls. The higher expression of genes that are involved in TG synthesis in 6-week-old SHRs may explain the higher TG content in these rats. Adenosine monophosphate-activated protein kinase phosphorylation and peroxisome proliferator-activated receptor α protein content were lower in cardiomyocytes in 18-week-old SHRs, suggesting a lower rate of ß-oxidation. The decreased protein content of α/ß-hydrolase domain-containing 5, adipose triglyceride lipase (ATGL) activator, and increased content of G0/G1 switch protein 2, ATGL inhibitor, indicating a lower rate of lipolysis in the heart in SHRs. In conclusion, the present study showed that the development of LV hypertrophy and myocardial dysfunction in SHRs is associated with triglyceride accumulation, attributable to a lower rate of lipolysis and ß-oxidation in cardiomyocytes.

Aurintricarboxylic acid protects isoproterenol induced left ventricular hypertrophy by modulating TWEAK signaling.

BACKGROUND: Cardiac hypertrophy is regarded as a compensation mechanism to overcome the increased workload. Aurintricarboxylic acid (ATA) is a derivative of quinomethanes and a selective inhibitor of TWEAK/Fn14 pathway. In this study, we investigated the effect of ATA on isoproterenol (ISO)-induced pathological cardiac hypertrophy. METHODS: Cardiac hypertrophy in H9C2 cells was induced using ISO 20 µM dissolved in PBS. H9C2 cells were treated with ATA (5 µM, 10 µM, 20 µM) followed by ISO stimulation for 24 h. Male SD rats were injected ISO (5 mg/kg/day, s.c) for 21 days and followed by treatment with ATA (10 mg/kg, i.p.) for 14 days. Cardiac functions were assessed. After sacrifice, hearts were subjected to histopathological and western blot analysis. RESULTS: In in-vitro results, upon ATA treatment, ICC results showed significant decrease in TWEAK and ANP expression. In in-vivo results, echocardiography showed significant restoration of cardiac function in ATA treated rats. Histopathological analysis showed a significant decrease in left ventricular wall thickness, cardiomyocytes width and reduced fibrosis in ATA treated rats. Western blotting showed decreased expression of the cardiac hypertrophy maker ANP, inflammatory markers including TWEAK and apoptotic markers after ATA treatment. CONCLUSION: These findings suggested that the TWEAK/Fn14 pathway could be a potential target for therapeutic exploration in ISO induced cardiac hypertrophy. ATA, as an inhibitor of this pathway, exerted significant cardioprotective effect against ISO-induced cardiac hypertrophy in rats.

Lessons from effect of etelcalcetide on left ventricular hypertrophy in patients with end-stage kidney disease.

PURPOSE OF REVIEW: Patients with end-stage kidney disease (ESKD) frequently develop left ventricular hypertrophy (LVH), which is associated with an exceptionally high risk of cardiovascular events and mortality. This review focuses on interventional studies that modify levels of fibroblast growth factor 23 (FGF23) and examine effects on myocardial hypertrophy, cardiovascular events and mortality. RECENT FINDINGS: Quantitative evaluations of trials of calcimimetics found no effects on cardiovascular events and cardiovascular and all-cause mortality when compared with placebo. However, a recent randomized, controlled trial of etelcalcetide versus alfacalcidol showed that etelcalcetide effectively inhibited the progression of LVH in comparison to vitamin D in patients on haemodialysis after 1 year of treatment. Prior to that, oral calcimimetic treatment has already been shown to reduce left ventricular mass in patients on haemodialysis, whereas treatment with active vitamin D or mineralocorticoids was ineffective in patients with ESKD. SUMMARY: Data from a recent trial of etelcalcetide on LVH suggest that FGF23 may be a possible therapeutic target for cardiac risk reduction in patients on haemodialysis. If these findings are confirmed by further research, it might be speculated that a treatment shift from active vitamin D towards FGF23-lowering therapy may occur in patients on haemodialysis.

Wnt Signaling Interactor WTIP (Wilms Tumor Interacting Protein) Underlies Novel Mechanism for Cardiac Hypertrophy.

BACKGROUND: The study of hypertrophic cardiomyopathy (HCM) can yield insight into the mechanisms underlying the complex trait of cardiac hypertrophy. To date, most genetic variants associated with HCM have been found in sarcomeric genes. Here, we describe a novel HCM-associated variant in the noncanonical Wnt signaling interactor WTIP (Wilms tumor interacting protein) and provide evidence of a role for WTIP in complex disease. METHODS: In a family affected by HCM, we used exome sequencing and identity-by-descent analysis to identify a novel variant in WTIP (p.Y233F). We knocked down WTIP in isolated neonatal rat ventricular myocytes with lentivirally delivered short hairpin ribonucleic acids and in Danio rerio via morpholino injection. We performed weighted gene coexpression network analysis for WTIP in human cardiac tissue, as well as association analysis for WTIP variation and left ventricular hypertrophy. Finally, we generated induced pluripotent stem cell-derived cardiomyocytes from patient tissue, characterized size and calcium cycling, and determined the effect of verapamil treatment on calcium dynamics. RESULTS: WTIP knockdown caused hypertrophy in neonatal rat ventricular myocytes and increased cardiac hypertrophy, peak calcium, and resting calcium in D rerio. Network analysis of human cardiac tissue indicated WTIP as a central coordinator of prohypertrophic networks, while common variation at the WTIP locus was associated with human left ventricular hypertrophy. Patient-derived WTIP p.Y233F-induced pluripotent stem cell-derived cardiomyocytes recapitulated cellular hypertrophy and increased resting calcium, which was ameliorated by verapamil. CONCLUSIONS: We demonstrate that a novel genetic variant found in a family with HCM disrupts binding to a known Wnt signaling protein, misregulating cardiomyocyte calcium dynamics. Further, in orthogonal model systems, we show that expression of the gene WTIP is important in complex cardiac hypertrophy phenotypes. These findings, derived from the observation of a rare Mendelian disease variant, uncover a novel disease mechanism with implications across diverse forms of cardiac hypertrophy.

Lipocalin-2: a novel link between the injured kidney and the bone.

PURPOSE OF REVIEW: Fibroblast growth factor 23 (FGF23) excess is associated with left ventricular hypertrophy (LVH) and early mortality in patients with chronic kidney disease (CKD) and in animal models. Elevated Lipocalin-2 (LCN2), produced by the injured kidneys, contributes to CKD progression and might aggravate cardiovascular outcomes. The current review aims to highlight the role of LCN2 in CKD, particularly its interactions with FGF23. RECENT FINDINGS: Inflammation, disordered iron homeostasis and altered metabolic activity are common complications of CKD, and are associated with elevated levels of kidney-produced LCN2 and bone-secreted FGF23. A recent study shows that elevated LCN2 increases FGF23 production, and contributes to cardiac injury in patients and animals with CKD, whereas LCN2 reduction in mice with CKD reduces FGF23, improves cardiovascular outcomes and prolongs lifespan. SUMMARY: In this manuscript, we discuss the potential pathophysiological functions of LCN2 as a major kidney-bone crosstalk molecule, linking the progressive decline in kidney function to excessive bone FGF23 production. We also review associations of LCN2 with kidney, cardiovascular and bone and mineral alterations. We conclude that the presented data support the design of novel therapeutic approaches to improve outcomes in CKD.

Regression from pathological hypertrophy in mice is sexually dimorphic and stimulus specific.

Pathological cardiac hypertrophy is associated with increased morbidity and mortality. Understanding the mechanisms whereby pathological cardiac growth can be reversed could be of therapeutic value. Here, we show that pathways leading to regression of pathological cardiac hypertrophy are strongly dependent on the hypertrophic trigger and are significantly modified by sex. Two pathological stimuli causing hypertrophy via distinct pathways were administered to male and female mice: angiotensin II (ANG II) or isoproterenol (Iso). Stimuli were removed after 7 days of treatment, and left ventricles (LVs) were studied at 1, 4, and 7 days. ANG II-treated females did not show regression after stimulus removal. Iso-treated males showed rapid LV hypertrophy regression. Somewhat surprisingly, RNAseq analysis at day 1 after removal of triggers revealed only 45 differentially regulated genes in common among all the groups, demonstrating distinct responses. Ingenuity pathway analysis predicted strong downregulation of the TGFß1 pathway in all groups except for ANG II-treated females. Consistently, we found significant downregulation of Smad signaling after stimulus removal including in ANG II-treated females. In addition, the ERK1/2 pathway was significantly reduced in the groups showing regression. Finally, protein degradation pathways were significantly activated only in Iso-treated males 1 day after stimulus removal. Our data indicate that TGFß1 downregulation may play a role in the regression of pathological cardiac hypertrophy via downregulation of the ERK1/2 pathway and activation of autophagy and proteasome activity in Iso-treated males. This work highlights that the reversal of pathological hypertrophy does not use universal signaling pathways and that sex potently modifies this process.NEW & NOTEWORTHY Pathological cardiac hypertrophy is a major risk factor for mortality and is thought to be largely irreversible in many individuals. Although cardiac hypertrophy itself has been studied extensively, very little is understood about its regression. It is important that we have a better understanding of mechanisms leading to regression, why this process is not reversible in some individuals and that sex differences need to be considered when contemplating therapies.

Comprehensive bioinformatics analysis identifies LAPTM5 as a potential blood biomarker for hypertensive patients with left ventricular hypertrophy.

Left ventricular hypertrophy (LVH) is a pivotal manifestation of hypertensive organ damage associated with an increased cardiovascular risk. However, early diagnostic biomarkers for assessing LVH in patients with hypertension (HT) remain indefinite. Here, multiple bioinformatics tools combined with an experimental verification strategy were used to identify blood biomarkers for hypertensive LVH. GSE74144 mRNA expression profiles were downloaded from the Gene Expression Omnibus (GEO) database to screen candidate biomarkers, which were used to perform weighted gene co-expression network analysis (WGCNA) and establish the least absolute shrinkage and selection operator (LASSO) regression model, combined with support vector machine-recursive feature elimination (SVM-RFE) algorithms. Finally, the potential blood biomarkers were verified in an animal model. A total of 142 hub genes in peripheral blood leukocytes were identified between HT with LVH and HT without LVH, which were mainly involved in the ATP metabolic process, oxidative phosphorylation, and mitochondrial structure and function. Notably, lysosomal associated transmembrane protein 5 (LAPTM5) was identified as the potential diagnostic marker of hypertensive LVH, which showed strong correlations with diverse marker sets of reactive oxygen species (ROS) and autophagy. RT-PCR validation of blood samples and cardiac magnetic resonance imaging (CMRI) showed that the expression of LAPTM5 was significantly higher in the HT with LVH model than in normal controls, LAPTM5 demonstrated a positive association with the left ventricle wall thickness as well as electrocardiogram (ECG) parameters widths of the QRS complex and QTc interval. In conclusion, LAPTM5 may be a potential biomarker for the diagnosis of LVH in patients with HT, and it can provide new insights for future studies on the occurrence and the molecular mechanisms of hypertensive LVH.

Mitochondrial Creatine Kinase Attenuates Pathologic Remodeling in Heart Failure.

BACKGROUND: Abnormalities in cardiac energy metabolism occur in heart failure (HF) and contribute to contractile dysfunction, but their role, if any, in HF-related pathologic remodeling is much less established. CK (creatine kinase), the primary muscle energy reserve reaction which rapidly provides ATP at the myofibrils and regenerates mitochondrial ADP, is down-regulated in experimental and human HF. We tested the hypotheses that pathologic remodeling in human HF is related to impaired cardiac CK energy metabolism and that rescuing CK attenuates maladaptive hypertrophy in experimental HF. METHODS: First, in 27 HF patients and 14 healthy subjects, we measured cardiac energetics and left ventricular remodeling using noninvasive magnetic resonance 31P spectroscopy and magnetic resonance imaging, respectively. Second, we tested the impact of metabolic rescue with cardiac-specific overexpression of either Ckmyofib (myofibrillar CK) or Ckmito (mitochondrial CK) on HF-related maladaptive hypertrophy in mice. RESULTS: In people, pathologic left ventricular hypertrophy and dilatation correlate closely with reduced myocardial ATP levels and rates of ATP synthesis through CK. In mice, transverse aortic constriction-induced left ventricular hypertrophy and dilatation are attenuated by overexpression of CKmito, but not by overexpression of CKmyofib. CKmito overexpression also attenuates hypertrophy after chronic isoproterenol stimulation. CKmito lowers mitochondrial reactive oxygen species, tissue reactive oxygen species levels, and upregulates antioxidants and their promoters. When the CK capacity of CKmito-overexpressing mice is limited by creatine substrate depletion, the protection against pathologic remodeling is lost, suggesting the ADP regenerating capacity of the CKmito reaction rather than CK protein per se is critical in limiting adverse HF remodeling. CONCLUSIONS: In the failing human heart, pathologic hypertrophy and adverse remodeling are closely related to deficits in ATP levels and in the CK energy reserve reaction. CKmito, sitting at the intersection of cardiac energetics and redox balance, plays a crucial role in attenuating pathologic remodeling in HF. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT00181259.

[Effect and mechanism of leonurine on pressure overload-induced cardiac hypertrophy in rats].

To investigate the effects of leonurine(Leo) on abdominal aortic constriction(AAC)-induced cardiac hypertrophy in rats and its mechanism. A rat model of pressure overload-induced cardiac hypertrophy was established by AAC method. After 27-d intervention with high-dose(30 mg·kg~(-1)) and low-dose(15 mg·kg~(-1)) Leo or positive control drug losartan(5 mg·kg~(-1)), the cardiac function was evaluated by hemodynamic method, followed by the recording of left ventricular systolic pressure(LVSP), left ventricular end-diastolic pressure(LVESP), as well as the maximum rate of increase and decrease in left ventricular pressure(±dp/dt_(max)). The degree of left ventricular hypertrophy was assessed based on heart weight index(HWI) and left ventricular mass index(LVWI). Myocardial tissue changes and the myocardial cell diameter(MD) were measured after hematoxylin-eosin(HE) staining. The contents of angiotensin Ⅱ(AngⅡ) and angiotensin Ⅱ type 1 receptor(AT1 R) in myocardial tissue were detected by ELISA. The level of Ca~(2+) in myocardial tissue was determined by colorimetry. The protein expression levels of phospholipase C(PLC), inositol triphosphate(IP3), AngⅡ, and AT1 R were assayed by Western blot. Real-time quantitative PCR(qRT-PCR) was employed to determine the mRNA expression levels of ß-myosin heavy chain(ß-MHC), atrial natriuretic factor(ANF), AngⅡ, and AT1 R. Compared with the model group, Leo decreased the LVSP, LVEDP, HWI, LVWI and MD values, but increased ±dp/dt_(max) of the left ventricle. Meanwhile, it improved the pathological morphology of myocardial tissue, reduced cardiac hypertrophy, edema, and inflammatory cell infiltration, decreased the protein expression levels of PLC, IP3, AngⅡ, AT1 R, as well as the mRNA expression levels of ß-MHC, ANF, AngⅡ, AT1 R, c-fos, and c-Myc in myocardial tissue. Leo inhibited AAC-induced cardiac hypertrophy possibly by influencing the RAS system.

O-ring-induced transverse aortic constriction (OTAC) is a new simple method to develop cardiac hypertrophy and heart failure in mice.

Suture-based transverse aortic constriction (TAC) in mice is one of the most frequently used experimental models for cardiac pressure overload-induced heart failure. However, the incidence of heart failure in the conventional TAC depends on the operator's skill. To optimize and simplify this method, we proposed O-ring-induced transverse aortic constriction (OTAC) in mice. C57BL/6J mice were subjected to OTAC, in which an o-ring was applied to the transverse aorta (between the brachiocephalic artery and the left common carotid artery) and tied with a triple knot. We used different inner diameters of o-rings were 0.50 and 0.45 mm. Pressure overload by OTAC promoted left ventricular (LV) hypertrophy. OTAC also increased lung weight, indicating severe pulmonary congestion. Echocardiographic findings revealed that both OTAC groups developed LV hypertrophy within one week after the procedure and gradually reduced LV fractional shortening. In addition, significant elevations in gene expression related to heart failure, LV hypertrophy, and LV fibrosis were observed in the LV of OTAC mice. We demonstrated the OTAC method, which is a simple and effective cardiac pressure overload method in mice. This method will efficiently help us understand heart failure (HF) mechanisms with reduced LV ejection fraction (HFrEF) and cardiac hypertrophy.

Empagliflozin Disrupts a Tnfrsf12a-Mediated Feed Forward Loop That Promotes Left Ventricular Hypertrophy.

PURPOSE: Although the cardioprotective benefits of sodium-glucose cotransporter 2 (SGLT2) inhibitors are now widely appreciated, the mechanisms underlying these benefits remain unresolved. Tumor necrosis factor receptor superfamily member 12a (Tnfrsf12a) is a receptor for tumor necrosis factor superfamily member 12 (Tnfsf12). Tnfrsf12a is highly inducible and plays a key role in the development of cardiac hypertrophy and heart failure. Here we set out to determine if SGLT2 inhibition affects the Tnfsf12/Tnfrsf12a system in the stressed myocardium. METHODS: C57BL/6N mice that had undergone sham or transverse aortic constriction (TAC) surgery were treated with either the SGLT2 inhibitor empagliflozin (400 mg/kg diet; 60-65 mg/kg/day) or standard chow alone and were followed for 8 weeks. Tnfrsf12a expression in mouse hearts was assessed by in situ hybridization, qRT-PCR, and immunoblotting. RESULTS: Left ventricular (LV) mass, end-systolic volume, and end-diastolic volume were all increased in TAC mice and were significantly lower with empagliflozin. Myocyte hypertrophy and interstitial fibrosis in TAC hearts were similarly attenuated with empagliflozin. Tnfrsf12a expression was upregulated in mouse hearts following TAC surgery but not in the hearts of empagliflozin-treated mice. In cultured cardiomyocytes, Tnfrsf12a antagonism attenuated the increase in cardiomyocyte size that was induced by phenylephrine. CONCLUSION: Empagliflozin attenuates LV enlargement in mice with hypertrophic heart failure. This effect may be mediated, at least in part, by a reduction in loading conditions which limits upregulation of the inducible, proinflammatory, and prohypertrophic TNF superfamily receptor, Tnfrsf12a. Disruption of the Tnfsf12/Tnfrsf12a feed forward system may contribute to the cardioprotective benefits of SGLT2 inhibition.

The bone at the intersection of kidney and heart disease.

Systemic inflammation and elevations in the hormone fibroblast growth factor 23 (FGF23) contribute to cardiac injury and death in patients with kidney disease. A new mechanistic study by Courbon et al. suggests that the bone connects the damaged kidney with the damaged heart by serving as the target for a kidney-derived proinflammatory factor and responding with FGF23 secretion.

MicroRNAs Regulating Renin-Angiotensin-Aldosterone System, Sympathetic Nervous System and Left Ventricular Hypertrophy in Systemic Arterial Hypertension.

MicroRNAs are small non-coding RNAs that regulate gene and protein expression. MicroRNAs also regulate several cellular processes such as proliferation, differentiation, cell cycle, apoptosis, among others. In this context, they play important roles in the human body and in the pathogenesis of diseases such as cancer, diabetes, obesity and hypertension. In hypertension, microRNAs act on the renin-angiotensin-aldosterone system, sympathetic nervous system and left ventricular hypertrophy, however the signaling pathways that interact in these processes and are regulated by microRNAs inducing hypertension and the worsening of the disease still need to be elucidated. Thus, the aim of this review is to analyze the pattern of expression of microRNAs in these processes and the possible associated signaling pathways.