Novel Therapeutic Target For Heart Failure Research Articles

Identification of diagnostic immune-related gene biomarkers for predicting heart failure after acute myocardial infarction.

Post-myocardial infarction heart failure (HF) is a major public health concern. Previous studies have reported the critical role of immune response in HF pathogenesis. However, limited studies have reported predictive immune-associated biomarkers for HF. So we attempted to identify potential immune-related indicators for HF early diagnosis and therapy guidance. This study identified two potential immune-related hub genes (IRHGs), namely CXCR5 and FOS, using bioinformatic approaches. The expression levels of CXCR5 and FOS and their ability to predict long-term HF were analyzed. Functional enrichment analysis revealed that the hub genes were enriched in immune system processes, including the interleukin-17 and nuclear factor-kappa B signaling pathways, which are involved in the pathogenesis of HF. Quantitative real-time polymerase chain reaction revealed that the Fos mRNA levels, but not the Cxcr5 mRNA levels, were downregulated in the mice of the HF group. This study successfully identified two IRHGs that were significantly and differentially expressed in the HF group and could predict long-term HF, providing novel insights for future studies on HF and developing novel therapeutic targets for HF.

Abstract P3195: Mitochondrial CaMKII Drives Cardiometabolic Dysfunction In Heart Failure

Background: Ca 2+ /calmodulin-dependent protein kinase II (CaMKII) is an established negative regulator of cardiac injury. Both the expression and activity levels of CaMKII delta, the primary cardiac isoform of this kinase, are elevated in models of heart failure (HF) such as ischemia-reperfusion (I/R) injury and following myocardial infarction (MI). This upregulation is due in part to CaMKII’s role in the regulation of excitation-contraction coupling, apoptosis, activation of hypertrophic programming, arrhythmias and pro-inflammatory signaling. Recently, a pool of mitochondrial CaMKII (mtCaMKII) has been identified; we have demonstrated that there is an observed increase in mitochondrial CaMKII activation with left ventricular dilation acutely following injury in a mouse model of MI. This deleterious post-MI phenotype is rescued with genetic mitochondrial CaMKII inhibition; conversely, mice with myocardial mitochondrial CaMKII overexpression present with a severe dilated cardiomyopathy phenotype, alterations in electron transport chain (ETC) activity, and decreased ATP production. Objective: To date, the molecular mechanisms by which CaMKII regulates mitochondrial energetics are unknown and present a novel therapeutic target for HF which we are currently studying. Methods: As we have identified changes in the activity of enzymes, particularly complexes I and II, in the mitochondrial ETC as well as TCA cycle in response to increased CaMKII levels or activity, we are in the process of assessing changes in the mitochondrial CaMKII interactome between uninjured and failing hearts. Utilizing liquid chromatography-mass spectrometry (LCMS) and proteomics analysis of both scaffolding interactions alongside a novel ATP analogue labeling technique, we have mapped novel mitochondrial proteins which interact with mtCaMKII. Significance: The identification of previously unknown mitochondrial pathways involving CaMKII may uncover promising pharmacological targets for cardiovascular therapeutics, as this kinase is a critical player in the progression of HF.

Mitochondrial GSNOR Alleviates Cardiac Dysfunction via ANT1 Denitrosylation.

The cardiac-protective role of GSNOR (S-nitrosoglutathione reductase) in the cytoplasm, as a denitrosylase enzyme of S-nitrosylation, has been reported in cardiac remodeling, but whether GSNOR is localized in other organelles and exerts novel effects remains unknown. We aimed to elucidate the effects of mitochondrial GSNOR, a novel subcellular localization of GSNOR, on cardiac remodeling and heart failure (HF). GSNOR subcellular localization was observed by cellular fractionation assay, immunofluorescent staining, and colloidal gold particle staining. Overexpression of GSNOR in mitochondria was achieved by mitochondria-targeting sequence-directed adeno-associated virus 9. Cardiac-specific knockout of GSNOR mice was used to examine the role of GSNOR in HF. S-nitrosylation sites of ANT1 (adenine nucleotide translocase 1) were identified using biotin-switch and liquid chromatography-tandem mass spectrometry. GSNOR expression was suppressed in cardiac tissues of patients with HF. Consistently, cardiac-specific knockout mice showed aggravated pathological remodeling induced by transverse aortic constriction. We found that GSNOR is also localized in mitochondria. In the angiotensin II-induced hypertrophic cardiomyocytes, mitochondrial GSNOR levels significantly decreased along with mitochondrial functional impairment. Restoration of mitochondrial GSNOR levels in cardiac-specific knockout mice significantly improved mitochondrial function and cardiac performance in transverse aortic constriction-induced HF mice. Mechanistically, we identified ANT1 as a direct target of GSNOR. A decrease in mitochondrial GSNOR under HF leads to an elevation of S-nitrosylation ANT1 at cysteine 160 (C160). In accordance with these findings, overexpression of either mitochondrial GSNOR or ANT1 C160A, non-nitrosylated mutant, significantly improved mitochondrial function, maintained the mitochondrial membrane potential, and upregulated mitophagy. We identified a novel species of GSNOR localized in mitochondria and found mitochondrial GSNOR plays an essential role in maintaining mitochondrial homeostasis through ANT1 denitrosylation, which provides a potential novel therapeutic target for HF.

Protein 4.1 family and ion channel proteins interact to regulate the process of heart failure in rats

Heart failure (HF) is a major cause of death in cardiovascular diseases worldwide, and its molecular mechanisms and effective prevention strategies remain to be further studied. The myocardial cytoskeleton plays a pivotal role in many heart diseases. However, little is known about the function of the membrane cytoskeleton 4.1 protein family and related regulatory mechanisms in the pathogenesis of HF. In this study, we detected the localization and expression of the protein 4.1 family and ion channel proteins in a rat HF model induced by doxorubicin (DOX), and studied the interactions between them. Our results showed that compared with the control group, the HF group displayed an increased expression level of protein 4.1R and decreased levels of protein 4.1 G and 4.1 N. The Nav1.5 protein levels were significantly increased, while the SERCA2a and Cav1.2 protein levels were significantly decreased in the HF group. Furthermore, there is co-localization and interaction between protein 4.1R and Nav1.5, protein 4.1 G and SERCA2a, protein 4.1 N and Cav1.2, respectively. Taken together, the results indicated that the protein 4.1 family might be involved in the occurrence and development of HF through its interaction with ion channel proteins, suggesting that 4.1 proteins may serve as a novel therapeutic target for HF.

Gut Microbiome and Precision Nutrition in Heart Failure: Hype or Hope?

Over the past decade, the gut microbiome has been shown to play an important role in the pathogenesis of heart failure (HF) and serves as a mediator that links host genomes and environmental exposure (especially dietary intake) to the development and progression of HF. Given that alterations in gut microbial composition and metabolism are commonly seen in patients with HF, the use of gut microbial metabolites as diagnostic and prognostic biomarkers, as well as novel therapeutic targets for HF, is promising. Alterations in gut microbial composition and function have bidirectional relationships with HF. Gut microbial metabolites, including short-chain fatty acids, bile acids, trimethylamine N-oxide (TMAO), and amino acid metabolites, have been shown to play a significant role in HF. For example, TMAO has been consistently demonstrated as an independent predictor of worse prognosis in patients with HF, and a potential therapeutic target for cardiac remodeling and HF. However, clinical studies on dietary interventions targeting gut microbial metabolites have demonstrated inconsistent findings, which could be from variations in the study population, gut microbial communities, and study designs. Measurement of gut microbial metabolites can improve risk stratification and potentially identify HF patients who are more likely to respond to personalized pharmacologic or dietary interventions targeting specific pathways associated with the gut microbiome.

Mir-30d Regulates Cardiac Remodeling by Intracellular and Paracrine Signaling.

Previous translational studies implicate plasma extracellular microRNA-30d (miR-30d) as a biomarker in left ventricular remodeling and clinical outcome in heart failure (HF) patients, although precise mechanisms remain obscure. To investigate the mechanism of miR-30d-mediated cardioprotection in HF. In rat and mouse models of ischemic HF, we show that miR-30d gain of function (genetic, lentivirus, or agomiR-mediated) improves cardiac function, decreases myocardial fibrosis, and attenuates cardiomyocyte (CM) apoptosis. Genetic or locked nucleic acid-based knock-down of miR-30d expression potentiates pathological left ventricular remodeling, with increased dysfunction, fibrosis, and cardiomyocyte death. RNA sequencing of in vitro miR-30d gain and loss of function, together with bioinformatic prediction and experimental validation in cardiac myocytes and fibroblasts, were used to identify and validate direct targets of miR-30d. miR-30d expression is selectively enriched in cardiomyocytes, induced by hypoxic stress and is acutely protective, targeting MAP4K4 (mitogen-associate protein kinase 4) to ameliorate apoptosis. Moreover, miR-30d is secreted primarily in extracellular vesicles by cardiomyocytes and inhibits fibroblast proliferation and activation by directly targeting integrin α5 in the acute phase via paracrine signaling to cardiac fibroblasts. In the chronic phase of ischemic remodeling, lower expression of miR-30d in the heart and plasma extracellular vesicles is associated with adverse remodeling in rodent models and human subjects and is linked to whole-blood expression of genes implicated in fibrosis and inflammation, consistent with observations in model systems. These findings provide the mechanistic underpinning for the cardioprotective association of miR-30d in human HF. More broadly, our findings support an emerging paradigm involving intercellular communication of extracellular vesicle-contained miRNAs (microRNAs) to transregulate distinct signaling pathways across cell types. Functionally validated RNA biomarkers and their signaling networks may warrant further investigation as novel therapeutic targets in HF.

A simplified herbal formula for the treatment of heart failure: Efficacy, bioactive ingredients, and mechanisms

Heart failure (HF) is a complex pathology for which single-agent therapy cannot provide comprehensive efficacy. Therefore, effective combination therapies for HF are increasingly emphasized. Multiple-component drugs derived from Chinese herbal formulae provide efficacy and safety when administered to patients with HF. Nuanxinkang (NXK) is a simplified Chinese herbal formula which has been widely applied in HF for decades. It exhibits comprehensive cardiac protective effects in HF patients as an adjuvant therapy, including improving heart function and quality-of-life, reducing inflammation, and regulating neurohormones. Nevertheless, the bioactive ingredients and mechanisms of action of NXK are unknown, which hinders its further application. Here, we examined the therapeutic efficacy of NXK in a mouse model of HF. Using transcriptome analysis and drug similarity analysis we found that NXK inhibits apoptosis and inflammation, while improving cardiac contraction and reversing myocardial fibrosis. In addition, we detected 21 bioactive species in NXK using UHPLC-MS analysis. Based on these data, we performed network pharmacology analysis to investigate ingredient-target-pathway interactions. We further confirmed 13 genes as potential targets, and assessed the effects of NXK on the AKT to validate the anti-apoptotic role of NXK both in vivo and in vitro. Thus, our work has identified a simplified herbal formula with efficacy against HF by exploring its constituents and mechanism of action, providing evidence for an innovative treatment strategy and novel therapeutic targets for HF.

A minireview of E4BP4/NFIL3 in heart failure.

Heart failure (HF) remains a major cause of morbidity and mortality worldwide. The primary cause identified for HF is impaired left ventricular myocardial function, and clinical manifestations may lead to severe conditions like pulmonary congestion, splanchnic congestion, and peripheral edema. Development of new therapeutic strategies remains the need of the hour for controlling the problem of HF worldwide. Deeper insights into the molecular mechanisms involved in etiopathology of HF indicate the significant role of calcium signaling, autocrine signaling pathways, and insulin-like growth factor-1 signaling that regulates the physiologic functions of heart growth and development such as contraction, metabolism, hypertrophy, cytokine signaling, and apoptosis. In view of these facts, a transcription factor (TF) regulating the myriad of these signaling pathways may prove as a lead candidate for development of therapeutics. Adenovirus E4 promoter-binding protein (E4BP4), also known as nuclear-factor, interleukin 3 regulated (NFIL3), a type of basic leucine zipper TF, is known to regulate the signaling processes involved in the functioning of heart. The current review discusses about the expression, structure, and functional role of E4BP4 in signaling processes with emphasis on calcium signaling mechanisms, autocrine signaling, and insulin-like growth factor II receptor-mediated processes regulated by E4BP4 that may regulate the pathogenesis of HF. We propose that E4BP4, being the critical component for the regulation of the above signaling processes, may serve as a novel therapeutic target for HF, and scientific investigations are merited in this direction.

Abstract 93: Genetic Deletion of Slc8b1, the Mitochondrial Sodium/Calcium Exchanger, Causes Sudden Cardiac Death and Overexpression Protects Against Myocardial Infarction and Pressure-Overload Heart Failure

Mitochondrial calcium ( m Ca 2+ ) signaling is critical for both energy production and the activation of cell death pathways in the heart. Further, m Ca 2+ overload is hypothesized to be a significant contributor to the development and progression of heart failure (HF). The mitochondrial sodium/calcium exchanger (mNCX) is hypothesized to be the primary mechanism of m Ca 2+ efflux, but to date no study has genetically confirmed its identity or function in an in vivo system. To investigate the role of mNCX in HF, we generated mutant mice with loxP sites flanking exons 5-7 of the candidate gene, Slc8b1 (also known as NCLX) , and crossed them with a tamoxifen (tamox)-inducible cardiac-specific Cre mouse to delete mNCX in the adult heart (mNCX-cKO). Cardiomyocytes isolated from mNCX-cKO mice displayed a significant reduction in m Ca 2+ efflux rate and Ca 2+ uptake capacity. Tamoxifen-induced ablation of mNCX resulted in sudden death with only 54% of mice surviving 8d post-tamoxifen treatment (Fig 1). Assessment of mNCX-cKO hearts 2d post-tamox revealed significant remodeling characterized by dilation and a decrease in %EF (Fig 2). Next, we generated a conditional, cardiac-specific mNCX overexpression mouse model (mNCX-Tg) to evaluate if increased m Ca 2+ efflux would alter the progression of HF. mNCX-Tg and controls were subjected to both myocardial infarction (LCA ligation) and pressure-overload induced HF (transverse aortic constriction). mNCX-Tg mice displayed preserved LV function, structure and a reduction in HF indices in both models. For the first time we show that mNCX is essential for m Ca 2+ efflux in cardiomyocytes and that mNCX represents a novel therapeutic target in HF.

Epigenetic mechanisms in heart failure pathogenesis.

Although neurohormonal antagonist and device therapies have improved outcomes in patients with systolic heart failure (HF), residual morbidity and mortality remain high.1,2 Novel HF therapeutic approaches thus remain an unmet clinical need of pressing urgency. Such approaches depend, in turn, on keener understanding of the molecular pathways underlying HF pathogenesis. Although a number of novel myocardial signaling effectors have been implicated as drivers of HF pathogenesis,1,3 translating these findings into human therapies has remained extremely challenging. Gene expression profiling studies in animal HF models4 and in human failing hearts5 consistently demonstrate aberrant gene control in HF. The term epigenetics—a fusion of epigenesis and genetics—was coined ≥50 years ago to describe the process of cell fate commitment during development.6 Today, the epigenome denotes the totality of sequence-independent processes that modulate cell-state–specific gene expression (eg, post-translational histone or DNA modifications and noncoding RNA/protein complex interactions with chromatin).7–10 The epigenome may differ between cell types, drive local formation of higher order chromatin structures, modulate transcription factor (TF) access to DNA, and preserve memory of past transcriptional activities.10 This review focuses on the chromatin-specific epigenetic regulatory mechanisms that may inform novel therapeutic targets in HF. We specifically highlight examples of chromatin remodeling, biochemical modifications to histones, and integrated features of chromatin-dependent signal transduction that are pertinent to cardiac biology. Other epigenetic pathways in HF, including miRNAs, have been extensively reviewed elsewhere.11,12 Eukaryotic cell identity or more broadly, cellular state, is largely governed by precise spatiotemporal coordination of gene expression.9 Pathological transformation from a normal to a diseased cardiomyocyte (eg, hypertrophied and hypocontractile) represents a cell state transition driven by defined transcriptional events. Dynamic interplay among …

Transcriptomic Biomarkers for Individual Risk Assessment in New-Onset Heart Failure

Prediction of prognosis remains a major unmet need in new-onset heart failure (HF). Although several clinical tests are in use, none accurately distinguish between patients with poor versus excellent survival. We hypothesized that a transcriptomic signature, generated from a single endomyocardial biopsy, could serve as a novel prognostic biomarker in HF. Endomyocardial biopsy samples and clinical data were collected from all patients presenting with new-onset HF from 1997 to 2006. Among a total of 350 endomyocardial biopsy samples, 180 were identified as idiopathic dilated cardiomyopathy. Patients with phenotypic extremes in survival were selected: good prognosis (event-free survival for at least 5 years; n=25) and poor prognosis (events [death, requirement for left ventricular assist device, or cardiac transplant] within the first 2 years of presentation with HF symptoms; n=18). We used human U133 Plus 2.0 microarrays (Affymetrix) and analyzed the data with significance analysis of microarrays and prediction analysis of microarrays. We identified 46 overexpressed genes in patients with good versus poor prognosis, of which 45 genes were selected by prediction analysis of microarrays for prediction of prognosis in a train set (n=29) with subsequent validation in test sets (n=14 each). The biomarker performed with 74% sensitivity (95% CI 69% to 79%) and 90% specificity (95% CI 87% to 93%) after 50 random partitions. These findings suggest the potential of transcriptomic biomarkers to predict prognosis in patients with new-onset HF from a single endomyocardial biopsy sample. In addition, our findings offer potential novel therapeutic targets for HF and cardiomyopathy.

Diacylglycerol Kinase .ZETA.Rescues G.ALPHA.q-Induced Heart Failure in Transgenic Mice

The G alpha q protein-coupled receptor (GPCR) signaling pathway, which includes diacylglycerol (DAG) and protein kinase C (PKC), plays a critical role in the development of cardiac hypertrophy and heart failure (HF). It has been reported that the expression of a constitutively active mutant of the G protein alpha q subunit in the hearts of transgenic mice (G alpha q-TG) induces cardiac hypertrophy and lethal HF. DAG kinase (DGK) catalyzes DAG and controls its cellular levels, thus acting as a regulator of GPCR signaling. It has been found that transgenic mice with cardiac-specific overexpression of DGK zeta (DGK zeta-TG) inhibit GPCR agonist-induced activation of the DAG-PKC signaling and subsequent cardiac hypertrophy, so this study tested the hypothesis that DGK zeta could rescue G alpha q-TG mice from developing HF. Double transgenic mice (G alpha q/DGK zeta-TG) with cardiac-specific overexpression of both DGK zeta and G alpha q were generated by crossing G alpha q-TG with DGK zeta-TG mice, and the pathophysiological consequences were analyzed. DGK zeta prevented cardiac dysfunction, determined by dilatation of left ventricular (LV) dimensions, reduction of LV fractional shortening, and marked increases in LV end-diastolic pressure in G alpha q-TG mice. Translocation of PKC isoforms, phosphorylation activity of c-jun N-terminal kinase and p38 mitogen-activated protein kinase in G alpha q-TG mice were attenuated by DGK zeta. DGK zeta improved the survival rate of G alpha q-TG mice. These results demonstrate the first evidence that DGK zeta blocks cardiac dysfunction and progression to lethal HF by activated G alpha q protein without detectable adverse effects in the in-vivo heart and suggest that DGK zeta is a novel therapeutic target for HF.