Project description:Background: Vitamin D deficiency is associated with cardiac hypertrophy and heart failure, and vitamin D therapy prevents the progression of cardiac hypertrophy in animal models. Here, we examine whether vitamin D therapy regresses pre-existing cardiac hypertrophy, and prevents the progression to heart failure. Methods and Results: When male Dahl salt-sensitive (DSS) rats are fed a high salt (HS) diet, all rats develop cardiac hypertrophy after 5 weeks (H). Thereafter, rats were treated with vehicle (V), paricalcitol (PC, an active vitamin D analog at 200ng, IP 3x/wk), enalapril (EP, 90ug/day), and PC+EP. All groups were continued on the HS diet and evaluated after 4 weeks of therapy. The PC and PC+EP, but not the V and EP-only groups, showed significant regression of pre-existing cardiac hypertrophy. The signs of decompensated heart failure were evident in the vehicle-treated group; these heart failure parameters significantly improved with PC, EP or PC+EP therapy. The expression of PKCe, which is regulated by Ca2+ and known to stimulate cardiac hypertrophy, was significantly increased in the vehicle group, and PC, EP or PC+EP effectively decreased PKCe activation. We also observed normalization of genetic alterations during progression to heart failure with PC treatment. Conclusions: PC treatment resulted in both the regression of pre-existing cardiac hypertrophy, and the attenuation of the progression to heart failure, compared to improvement in progression to heart failure by EP alone. These beneficial findings in the heart were associated with inhibition of PKCe activation, and reversal of gene alterations.
Project description:Background: Vitamin D deficiency is associated with cardiac hypertrophy and heart failure, and vitamin D therapy prevents the progression of cardiac hypertrophy in animal models. Here, we examine whether vitamin D therapy regresses pre-existing cardiac hypertrophy, and prevents the progression to heart failure. Methods and Results: When male Dahl salt-sensitive (DSS) rats are fed a high salt (HS) diet, all rats develop cardiac hypertrophy after 5 weeks (H). Thereafter, rats were treated with vehicle (V), paricalcitol (PC, an active vitamin D analog at 200ng, IP 3x/wk), enalapril (EP, 90ug/day), and PC+EP. All groups were continued on the HS diet and evaluated after 4 weeks of therapy. The PC and PC+EP, but not the V and EP-only groups, showed significant regression of pre-existing cardiac hypertrophy. The signs of decompensated heart failure were evident in the vehicle-treated group; these heart failure parameters significantly improved with PC, EP or PC+EP therapy. The expression of PKCe, which is regulated by Ca2+ and known to stimulate cardiac hypertrophy, was significantly increased in the vehicle group, and PC, EP or PC+EP effectively decreased PKCe activation. We also observed normalization of genetic alterations during progression to heart failure with PC treatment. Conclusions: PC treatment resulted in both the regression of pre-existing cardiac hypertrophy, and the attenuation of the progression to heart failure, compared to improvement in progression to heart failure by EP alone. These beneficial findings in the heart were associated with inhibition of PKCe activation, and reversal of gene alterations. Male Dahl salt-sensitive rats (Harlan Sprague–Dawley, Somerville, NJ) were bred and fed a normal diet until 6 weeks of age. To generate pressure overload cardiac hypertrophy, they were then fed a high salt (6%NaCl) diet for the next 5 weeks. Data for baseline hypertrophic group (H) was obtained at the end of 11 weeks. Among H group animals, they were divided as follows and treated for an additional 4 weeks: 1) continuation of the HS diet with vehicle injection (H+V); 2) continuation of the HS diet with paricalcitol (19-nor-1,25-(OH)2 D2) (PC) (200ng IP 3x/wk) injection (H+PC); 3) continuation of the HS diet with low dose enalapril (EP), an angiotensin-converting enzyme inhibitor, infusion via osmotic pump and vehicle injection (H+EP+V); and 4) continuation of the HS diet with low dose EP infusion via osmotic pump and PC (200ng IP 3x/wk) injection (H+EP+PC). PC was prepared with 95% propylene glycol and 5% ethyl alcohol solution and administered three times a week on Monday, Wednesday, and Friday for 4 consecutive weeks. Vehicle groups received vehicle injections on the same schedule. Two groups of rats were implanted with pumps to deliver EP for 4 weeks. Since the reduction in blood pressure (BP) from high doses of EP would have effects on cardiac hypertrophy and progression to heart failure, we used low dose EP at 90ug/day, a maximum dose that did not significantly decrease BP in these rats, to study the effects of EP and PC that are independent of BP.
Project description:Numerous studies found intestinal microbiota alterations which are thought to affect the development of various diseases through the production of gut-derived metabolites. However, the specific metabolites and their pathophysiological contribution to cardiac hypertrophy or heart failure progression still remain unclear. N,N,N-trimethyl-5-aminovaleric acid (TMAVA), derived from trimethyllysine through the gut microbiota, was elevated with gradually increased risk of cardiac mortality and transplantation in a prospective heart failure cohort (n=1647). TMAVA treatment aggravated cardiac hypertrophy and dysfunction in high-fat diet-fed mice. Decreased fatty acid oxidation (FAO) is a hallmark of metabolic reprogramming in the diseased heart and contributes to impaired myocardial energetics and contractile dysfunction. Proteomics uncovered that TMAVA disturbed cardiac energy metabolism, leading to inhibition of FAO and myocardial lipid accumulation. TMAVA treatment altered mitochondrial ultrastructure, respiration and FAO and inhibited carnitine metabolism. Mice with γ-butyrobetaine hydroxylase (BBOX) deficiency displayed a similar cardiac hypertrophy phenotype, indicating that TMAVA functions through BBOX. Finally, exogenous carnitine supplementation reversed TMAVA induced cardiac hypertrophy. These data suggest that the gut microbiota-derived TMAVA is a key determinant for the development of cardiac hypertrophy through inhibition of carnitine synthesis and subsequent FAO.
Project description:Epigenetic status has been linked to cardiac hypertrophy and heart failure. Histone deacetylase inhibitors are promising drugs for preventing cardiac remodeling. We previously demonstrated very different patterns of histone H3 lysine 9 trimethylation (H3K9me3) and histone H3 lysine 4 trimethylation (H3K4me3) in failing hearts compared to control hearts in both animal models and clinical heart specimens. Here, we focused on a heart failure-specific histone modification, H3K9me3, and investigated the prognostic efficacy of administering a histone H3K9 methyltransferase inhibitor, chaetocin, to Dahl salt-sensitive rats, an animal model of heart failure. Chaetocin delayed the timing of transition from cardiac hypertrophy to heart failure, and prolonged survival in this animal model. Mitochondrial dysfunction was improved with inhibitor use in the failing heart. ChIP-seq analysis demonstrated that heart failure caused an increase in H3K9me3 alignments in thousands of repetitive elements, including regions neighboring mitochondrial genes, and a corresponding reduction of this effect with inhibitor use. However, at 35 loci, heart failure was conversely associated with a reduction in H3K9me3 alignments, and inhibitor use reversed this effect. These data suggest that excessive heterochromatinization of repetitive elements in the failing heart might impair pumping function with mitochondrial gene silencing. H3K9 methyltransferase inhibitors may be a promising novel therapy for chronic heart failure.
Project description:Heart failure is characterized by the inability of the heart to pump effectively and generate proper blood circulation to meet the body's needs; it is a devastating condition that affects more than 100 million people globally. In spite of this, little is known about the mechanisms regulating the transition from cardiac hypertrophy to heart failure. Previously, we identified a cardiomyocyte-enriched gene, CIP, which regulates cardiac homeostasis under pathological stimulation. Here, we show that the cardiac transcriptional factor GATA4 binds the promotor of CIP gene and regulates its expression. We further determined that both CIP mRNA and protein decrease in diseased human hearts. In a mouse model, induced cardiac-specific overexpression of CIP after the establishment of cardiac hypertrophy protects the heart by inhibiting disease progression toward heart failure. Transcriptome analyses revealed that the IGF, mTORC2 and TGFβ signaling pathways mediate the inhibitory function of CIP on pathologic cardiac remodeling. Our study demonstrates GATA4 as an upstream regulator of CIP gene expression in cardiomyocytes, as well as the clinical significance of CIP expression in human heart disease. More importantly, our investigation suggests CIP is a key regulator of the transition from cardiac hypertrophy to heart failure. The ability of CIP to intervene in the onset of heart failure suggests a novel therapeutic avenue of investigation forthe prevention of heart disease progression.
Project description:Cardiac hypertrophy is an important and independent risk factor for the development of cardiac myopathy that may lead to heart failure. Cardiac hypertrophy manifests as an enlargement of the individual cardiomyocytes, which impairs the function of the heart. The only way to cure end-stage cardiac myopathy is by heart transplantation, a possibility limited due to lack of donor hearts. Therefore, early diagnosis of cardiac hypertrophy is needed in order to be able to initiate interventions that may prevent further progression of the disease. The mechanisms underlying the development of cardiac hypertrophy are yet not well understood. To increase the knowledge about mechanisms and regulatory pathways involved in the progression of cardiac hypertrophy, we have developed a human induced pluripotent stem cell (hiPSC)-based in vitro model of cardiac hypertrophy and performed extensive characterization of the model using multi-omics analyses. In a series of experiments, hiPSC-derived cardiomyocytes were stimulated with Endothelin-1 for 8, 24, 48 and 72 hours and their transcriptome and secreted proteome were analyzed thoroughly. The transcriptomic data show many enriched canonical pathways related to cardiac hypertrophy already at the earliest time point, e.g., cardiac hypertrophy signaling, actin cytoskeleton signaling and PI3K/AKT signaling. Cluster analysis of the differentially expressed genes showed that there are numerous clusters of genes that are dysregulated over the time period of 8 to 72h. An integrated transcriptome-secretome analysis enabled the identification of multimodal biomarkers of high relevance for monitoring early cardiac hypertrophy progression. Taken together, the results from this study demonstrate that our in vitro model displays a hypertrophic response on transcriptomic- and secreted proteomic level. The results also provide novel insight into the underlying mechanisms of cardiac hypertrophy and novel putative early cardiac hypertrophy biomarkers have been identified that will be further validated to assess their clinical relevance.
Project description:To investigate molecular mechanisms involved in the development of cardiac hypertrophy and heart failure, a tetracycline-regulated transgenic system to conditionally switch a constitutively-active form of the Akt1 protein kinase on or off in the adult heart was developed. Short-term activation (2 weeks) of Akt1 resulted in completely reversible hypertrophy with maintained contractility. In contrast, chronic Akt1 activation (6 weeks) induced extensive cardiac hypertrophy, severe contractile dysfunction, and massive interstitial fibrosis. The focus of this study was to create a transcript expression profile of the heart as it undergoes reversible Akt1-mediated hypertrophy and during the transition from compensated hypertrophy to heart failure. Heart tissue was analyzed before transgene induction, 2 weeks after transgene induction, 2 weeks of transgene induction followed by 2 days of repression, 6 weeks after transgene induction and 6 weeks of transgene induction followed by 2 weeks of repression. Acute over expression of Akt1 (2 weeks) leads to changes in the expression of 826 transcripts relative to non-induced hearts, whereas chronic induction (6 weeks) led to changes in the expression of 1611, of which 65% represented transcripts that were regulated during the pathological phase of heart growth. Another set of genes identified were uniquely regulated during heart regression but not growth, indicating that non-overlapping transcription programs participate in the processes of cardiac hypertrophy and atrophy. These data define the gene regulatory programs downstream of Akt that control heart size and contribute to the transition from compensatory hypertrophy to heart failure. Keywords: transgenic mice, Akt1, time course, cardiac hypertrophy and contractile dysfunction, DNA microarrays
Project description:Atherosclerosis and pressure overload are major risk factors for the development of heart failure in patients. Cardiac hypertrophy often precedes the development of heart failure. However, underlying mechanisms are incompletely understood. To investigate pathomechanisms underlying the transition from cardiac hypertrophy to heart failure we used experimental models of atherosclerosis- and pressure overload-induced cardiac hypertrophy and failure, i.e. apolipoprotein E (apoE)-deficient mice, which develop heart failure at an age of 18 months, and non-transgenic C57BL/6J (B6) mice with heart failure triggered by 6 months of pressure overload induced by abdominal aortic constriction (AAC). The development of heart failure was monitored by echocardiography, invasive hemodynamics and histology. The microarray gene expression study of cardiac genes was performed with heart tissue from failing hearts relative to hypertrophic and healthy heart tissue, respectively. The microarray study revealed that the onset of heart failure was accompanied by a strong up-regulation of cardiac lipid metabolism genes involved in fat synthesis, storage and oxidation.
Project description:Right ventricular heart failure (RVF) associated with pulmonary hypertension (PH) is characterized by a distinct gene expression pattern when compared with functional compensatory hypertrophy. Carvedilol treatment after RVF has been established reduces right ventricle (RV) hypertrophy and improves the RV function. In addition, carvedilol treatment has been shown to alter the gene expression of select genes. We sought to identify, on a genome-wide basis, the effect of carvedilol on gene expression. RVF was induced in male Sprague-Dawley rats by the combination of VEGF-receptor blockade and chronic hypoxia; thereafter, one group was treated with carvedilol. RNA was isolated from the RV and subjected to microarray analysis. A prediction analysis of the carvedilol-treated RVs showed that carvedilol treated RVs most resembled in their expression pattern the RVF pattern. However, an analysis beyond the boundaries of the prediction set revealed a small set of genes associated with carvedilol reversal of RVF. Pathway analysis of this set of genes revealed expression changes of genes involved in cardiac hypertrophy, mitochondrial dysfunction, protein ubiquitination, and sphingolipid metabolism. Genes encoding proteins in the cardiac hypertrophy and protein ubiquitination pathways were downregulated in the RV by carvedilol, while genes encoding proteins in the mitochondrial dysfunction and sphingolipid metabolism pathways were upregulated by carvedilol.
Project description:An important event in the pathogenesis of heart failure is the development of pathological cardiac hypertrophy. In cultured cardiac cardiomyocytes, the transcription factor Gata4 is required for agonist-induced cardiomyocyte hypertrophy. We hypothesized that in the intact organism Gata4 is an important regulator of postnatal heart function and of the hypertrophic response of the heart to pathological stress. To test this hypothesis, we studied mice heterozygous for deletion of the second exon of Gata4 (G4D). At baseline, G4D mice had mild systolic and diastolic dysfunction associated with reduced heart weight and decreased cardiomyocyte number. After transverse aortic constriction (TAC), G4D mice developed overt heart failure and eccentric cardiac hypertrophy, associated with significantly increased fibrosis and cardiomyocyte apoptosis. Inhibition of apoptosis by overexpression of the insulin-like growth factor 1 receptor prevented TAC-induced heart failure in G4D mice. Unlike WT-TAC controls, G4D-TAC cardiomyocytes hypertrophied by increasing in length more than width. Gene expression profiling revealed upregulation of genes associated with apoptosis and fibrosis, including members of the TGF? pathway. Our data demonstrate that Gata4 is essential for cardiac function in the postnatal heart. After pressure overload, Gata4 regulates the pattern of cardiomyocyte hypertrophy and protects the heart from load-induced failure. Experiment Overall Design: We reasoned that if Gata4 was a crucial regulator of pathways necessary for cardiac hypertrophy, then modest reductions of Gata4 activity should result in an observable cardiac phenotype. To test this hypothesis, we used gene targeted mice that express reduced levels of Gata4. We characterized these mice at baseline and after pressure Experiment Overall Design: overload.