Myocardial metabolism in heart failure: Purinergic signalling and other metabolic concepts

[Morphofunctional Analysis of the Role of Epicardial Adipose Tissue in the Formation of the Obesity Paradox in Chronic Heart Failure]

Based on the available modern medical literature, the article summarizes data on the morpho-functional significance of epicardial adipose tissue (EAT) in health and heart failure, analyzes the likelihood and reliability of the formation of the obesity paradox, and also discusses its possible morpho-functional mechanisms. The authors reviewed and analyzed the consequences of the obesity paradox in the aspect of the normal EAT phenotype protectivity. The review proposed ways of further research in this direction aimed at a deep anatomical and physiological analysis and at determining the morpho-functional role of EAT in the adaptive mechanisms of myocardial trophic provision, which may be an important part of the pathogenetic connection between obesity and CHF and, therefore, can improve outcomes in such patients.

Pannexin 1 Channels Control Cardiomyocyte Metabolism and Neutrophil Recruitment During Non-Ischemic Heart Failure

Pannexin 1 (PANX1), a ubiquitously expressed ATP release membrane channel, has been shown to play a role in inflammation, blood pressure regulation, and myocardial infarction. However, a possible role of PANX1 in cardiomyocytes in the progression of heart failure has not yet been investigated. We generated a novel mouse line with constitutive deletion of PANX1 in cardiomyocytes (Panx1 MyHC6 ). PANX1 deletion in cardiomyocytes had no effect on unstressed heart function but increased the glycolytic metabolism both in vivo and in vitro . In vitro , treatment of H9c2 cardiomyocytes with isoproterenol led to PANX1-dependent release of ATP and Yo-Pro-1 uptake, as assessed by pharmacological blockade with spironolactone and siRNA-mediated knock-down of PANX1. To investigate non-ischemic heart failure and the preceding cardiac hypertrophy we administered isoproterenol, and we demonstrate that Panx1 MyHC6 mice were protected from systolic and diastolic left ventricle volume increases and cardiomyocyte hypertrophy. Moreover, we found that Panx1 MyHC6 mice showed decreased isoproterenol-induced recruitment of immune cells (CD45 + ), particularly neutrophils (CD11b + , Ly6g + ), to the myocardium. Together these data demonstrate that PANX1 deficiency in cardiomyocytes impacts glycolytic metabolism and protects against cardiac hypertrophy in non-ischemic heart failure at least in part by reducing immune cell recruitment. Our study implies PANX1 channel inhibition as a therapeutic approach to ameliorate cardiac dysfunction in heart failure patients.

Advances in Metabolic Remodeling and Intervention Strategies in Heart Failure

The heart is the most energy-demanding organ throughout the whole body. Perturbations or failure in energy metabolism contributes to heart failure (HF), which represents the advanced stage of various heart diseases. The poor prognosis and huge economic burden associated with HF underscore the high unmet need to explore novel therapies targeting metabolic modulators beyond conventional approaches focused on neurohormonal and hemodynamic regulators. Emerging evidence suggests that alterations in metabolic substrate reliance, metabolic pathways, metabolic by-products, and energy production collectively regulate the occurrence and progression of HF. In this review, we provide an overview of cardiac metabolic remodeling, encompassing the utilization of free fatty acids, glucose metabolism, ketone bodies, and branched-chain amino acids both in the physiological condition and heart failure. Most importantly, the latest advances in pharmacological interventions are discussed as a promising therapeutic approach to restore cardiac function, drawing insights from recent basic research, preclinical and clinical studies.

Current Pharmacology and Modulation of the Purinergic System in Takotsubo Syndrome Triggered by Cytokine Storm

Studies show that with the COVID-19 pandemic, the world's population went through multiple stress and anxiety factors, generating serious psychological problems, in addition, the virus also caused damage and physical stress to those contaminated. In this way, the intense emotional experiences and stressful effects on the body caused by SARS-CoV-2 are capable of triggering the excessive release of catecholamines in the body. Thus, the framework of Takotsubo Syndrome is characterized by myocardial dysfunction as a response of cardiac receptors to the spillage of such hormones in an unregulated way in the human body. The purinergic system plays a central role in this process, as it actively participates in actions responsible for the syndromic cascade, such as the stress generated by the cytokine storm triggered by the virus and the stimulation of deregulated catecholamine release. Therefore, further pharmacological studies on the role of purines in this pathology should be developed in order to avoid the evolution of the syndrome and to modulate its P1 and P2 receptors aiming at developing means of reversing or treating the Takotsubo Syndrome.

Protective effect of empagliflozin against palmitate-induced lipotoxicity through AMPK in H9c2 cells

Sodium-glucose cotransporter 2 (SGLT2) inhibitors have recently emerged as novel cardioprotective agents. However, their direct impact on cardiomyocyte injury is yet to be studied. In this work, we investigate the underlying molecular mechanisms of empagliflozin (EMPA), an SGLT2 inhibitor, in mitigating palmitate (PA)-induced cardiomyocyte injury in H9c2 cells. We found that EMPA significantly attenuated PA-induced impairments in insulin sensitivity, ER stress, inflammatory cytokine gene expression, and cellular apoptosis. Additionally, EMPA elevated AMP levels, activated the AMPK pathway, and increased carnitine palmitoyl transferase1 (CPT1) gene expression, which collectively enhanced fatty acid oxidation and reduced stress signals. This study reveals a novel mechanism of EMPA's protective effects against PA-induced cardiomyocyte injury, providing new therapeutic insights into EMPA as a cardioprotective agent.

Urolithin A protects severe acute pancreatitis-associated acute cardiac injury by regulating mitochondrial fatty acid oxidative metabolism in cardiomyocytes

Severe acute pancreatitis (SAP) often develops into acute cardiac injury (ACI), contributing to the high mortality of SAP. Urolithin A (UA; 3,8-dihydroxy-6H-dibenzopyran-6-one), a natural polyphenolic compound, has been extensively studied and shown to possess significant anti-inflammatory effects. Nevertheless, the specific effects of UA in SAP-associated acute cardiac injury (SACI) have not been definitively elucidated. Here, we investigated the therapeutic role and mechanisms of UA in SACI using transcriptomics and untargeted metabolomics analyses in a mouse model of SACI and in vitro studies. SACI resulted in severely damaged pancreatic and cardiac tissues with myocardial mitochondrial dysfunction and mitochondrial metabolism disorders. UA significantly reduced the levels of lipase, amylase and inflammatory factors, attenuated pathological damage to pancreatic and cardiac tissues, and reduced myocardial cell apoptosis and oxidative stress in SACI. Moreover, UA increased mitochondrial membrane potential and adenosine triphosphate production and restored mitochondrial metabolism, but the efficacy of UA was weakened by the inhibition of CPT1. Therefore, UA can attenuate cardiac mitochondrial dysfunction and reduce myocardial apoptosis by restoring the balance of mitochondrial fatty acid oxidation metabolism. CPT1 may be a potential target. This study has substantial implications for advancing our understanding of the pathogenesis and drug development of SACI.

Function and regulation of ubiquitin-like SUMO system in heart

The small ubiquitin-related modifier (SUMOylation) system is a conserved, reversible, post-translational protein modification pathway covalently attached to the lysine residues of proteins in eukaryotic cells, and SUMOylation is catalyzed by SUMO-specific activating enzyme (E1), binding enzyme (E2) and ligase (E3). Sentrin-specific proteases (SENPs) can cleave the isopeptide bond of a SUMO conjugate and catalyze the deSUMOylation reaction. SUMOylation can regulate the activity of proteins in many important cellular processes, including transcriptional regulation, cell cycle progression, signal transduction, DNA damage repair and protein stability. Biological experiments in vivo and in vitro have confirmed the key role of the SUMO conjugation/deconjugation system in energy metabolism, Ca2+ cycle homeostasis and protein quality control in cardiomyocytes. In this review, we summarized the research progress of the SUMO conjugation/deconjugation system and SUMOylation-mediated cardiac actions based on related studies published in recent years, and highlighted the further research areas to clarify the role of the SUMO system in the heart by using emerging technologies.

The ATP-dependent Pathways and Human Diseases

Adenosine triphosphate (ATP) is one of the most important molecules of life, present both inside the cells and extracellularly. It is an essential building block for nucleic acids biosynthesis and crucial intracellular energy storage. However, one of the most interesting functions of ATP is the role of a signaling molecule. Numerous studies indicate the involvement of ATP-dependent pathways in maintaining the proper functioning of individual tissues and organs. Herein, the latest data indicating the ATP function in the network of intra- and extracellular signaling pathways including purinergic signaling, MAP kinase pathway, mTOR and calcium signaling are collected. The main ATP-dependent processes maintaining the proper functioning of the nervous, cardiovascular and immune systems, as well as skin and bones, are summarized. The disturbances in the ATP amount, its cellular localization, or interaction with target elements may induce pathological changes in signaling pathways leading to the development of serious diseases. The impact of an ATP imbalance on the development of dangerous health dysfunctions such as neurodegeneration diseases, cardiovascular diseases (CVDs), diabetes mellitus, obesity, cancers and immune pathogenesis are discussed here.

Synergistic cardioprotective ability of co-administration of Moringa supplemented diets and acarbose in diabetic cardiomyopathy involves attenuation of cholinergic, purinergic, monoaminergic, renin-angiotensin system, and antioxidant pathways

One of the major complications of diabetes mellitus (DM) is diabetic cardiomyopathy (DCM) due to the multifaceted therapy involved. Here, we evaluated the combinatorial effect of Moringa leaf (ML) and seed (MS) supplemented diets plus acarbose (ACA) on cardiac acetylcholinesterase (AChE), adenosine triphosphatase (ATPase), adenosine deaminase (ADA), monoamine oxidase (MAO), arginase, angiotensin-I converting enzyme (ACE), and lactate dehydrogenase (LDH) activities, thiobarbituric acid reactive species (TBARS), and thiols levels. The diets and ACA (25 mg/kg) were administered for 14 days. The fasting blood glucose level (FBGL), cardiac AChE, ATPase, ADA, MAO, arginase, ACE, LDH activities, and TBARS and thiol levels were determined. Relative to the normal rats, the biomarkers were significantly increased in DM rats but were suppressed significantly in the diets plus ACA-treated rats while improving antioxidant status, with the 4% Moringa plus ACA proving outstanding compared to individual ML/MS and ACA. In addition, ML-supplemented diets with/without ACA had better effects compared to MS with/without ACA, respectively. In conclusion, the combination of ML/MS supplemented diets and ACA synergistically modulates the tested biochemicals. However, the effect on blood vessels and the nerves that control the heart, stiffness of left ventricular (LV) hypertrophy, fibrosis, cell signaling abnormalities, related gene expression, clinical trials, and echocardiology studies should be further investigated to affirm this claim. PRACTICAL APPLICATIONS: Moringa oleifera has been a vocal appetite in mitigating cardiovascular disease induced by diabetes, but the formulation of a medicinal diet as an ameliorative route of attention to the pathology is fairly addressed, not talking of its combination with the synthetic antidiabetic drug, such as ACA. Based on this experiment, it is imperative to explore such an idea. This research shows that co-administration of moringa leaf/seed formulated diets plus ACA exhibits a synergistic effect in DCM management. However, further research is needed in this field of experiment.

Targeting Myocardial Substrate Metabolism in the Failing Heart: Ready for Prime Time?

PURPOSE OF REVIEW

We review the clinical benefits of altering myocardial substrate metabolism in heart failure.

RECENT FINDINGS

Modulation of cardiac substrates (fatty acid, glucose, or ketone metabolism) offers a wide range of therapeutic possibilities which may be applicable to heart failure. Augmenting ketone oxidation seems to offer great promise as a new therapeutic modality in heart failure. The heart has long been recognized as metabolic omnivore, meaning it can utilize a variety of energy substrates to maintain adequate ATP production. The adult heart uses fatty acid as a major fuel source, but it can also derive energy from other substrates including glucose and ketone, and to some extent pyruvate, lactate, and amino acids. However, cardiomyocytes of the failing heart endure remarkable metabolic remodeling including a shift in substrate utilization and reduced ATP production, which account for cardiac remodeling and dysfunction. Research to understand the implication of myocardial metabolic perturbation in heart failure has grown in recent years, and this has raised interest in targeting myocardial substrate metabolism for heart failure therapy. Due to the interdependency between different pathways, the main therapeutic metabolic approaches include inhibiting fatty acid uptake/fatty acid oxidation, reducing circulating fatty acid levels, increasing glucose oxidation, and augmenting ketone oxidation.

β-Hydroxybutyrate in Cardiovascular Diseases : A Minor Metabolite of Great Expectations

Despite recent advances in therapies, cardiovascular diseases ( CVDs ) are still the leading cause of mortality worldwide. Previous studies have shown that metabolic perturbations in cardiac energy metabolism are closely associated with the progression of CVDs. As expected, metabolic interventions can be applied to alleviate metabolic impairments and, therefore, can be used to develop therapeutic strategies for CVDs. β-hydroxybutyrate (β-HB) was once known to be a harmful and toxic metabolite leading to ketoacidosis in diabetes. However, the minor metabolite is increasingly recognized as a multifunctional molecular marker in CVDs. Although the protective role of β-HB in cardiovascular disease is controversial, increasing evidence from experimental and clinical research has shown that β-HB can be a “super fuel” and a signaling metabolite with beneficial effects on vascular and cardiac dysfunction. The tremendous potential of β-HB in the treatment of CVDs has attracted many interests of researchers. This study reviews the research progress of β-HB in CVDs and aims to provide a theoretical basis for exploiting the potential of β-HB in cardiovascular therapies.

Mitochondria-Mediated Cardiovascular Benefits of Sodium-Glucose Co-Transporter 2 Inhibitors

Several recent cardiovascular trials of SGLT 2 (sodium-glucose cotransporter 2) inhibitors revealed that they could reduce adverse cardiovascular events in patients with T2DM (type 2 diabetes mellitus). However, the exact molecular mechanism underlying the beneficial effects that SGLT2 inhibitors have on the cardiovascular system is still unknown. In this review, we focus on the molecular mechanisms of the mitochondria-mediated beneficial effects of SGLT2 inhibitors on the cardiovascular system. The application of SGLT2 inhibitors ameliorates mitochondrial dysfunction, dynamics, bioenergetics, and ion homeostasis and reduces the production of mitochondrial reactive oxygen species, which results in cardioprotective effects. Herein, we present a comprehensive overview of the impact of SGLT2 inhibitors on mitochondria and highlight the potential application of these medications to treat both T2DM and cardiovascular diseases.

The Potential of Metabolism-Related Gene OGDHL as a Biomarker for Myocardial Remodeling in Dilated Cardiomyopathy

The development of dilated cardiomyopathy (DCM) is accompanied by a series of metabolic disorders, resulting in myocardial remodeling or exacerbation, while the mechanism remains not completely clear. This study was to find out the key metabolism-related genes involved in the onset of DCM, providing new insight into the pathogenesis of this disease. The datasets of GSE57338, GSE116250, and GSE5406 associated with hearts of patients with DCM were downloaded from the Gene Expression Omnibus database. GSE57338 was analyzed to screen out metabolism-related differentially expressed genes (DEGs), while GSE116250 and GSE5406 were utilized to verify the optimal genes through R software. Support vector machine recursive feature elimination algorithm and least absolute shrinkage and selection operator algorithm were used to determine key genes. Finally, 6 of 39 metabolism-related DEGs were screened out and identified as the optimal genes. After quantitative reverse-transcription polymerase chain reaction (qRT-PCR) validation performed on the samples drawn from the left ventricles of human hearts, it showed that only the expression of oxoglutarate dehydrogenase-like (OGDHL) increased while PLA2G2 decreased significantly in patients with DCM compared with non-failing donors, respectively. Furthermore, the higher OGDHL protein expression, except the change of PLA2G2, was also found in DCM hearts, and its mRNA expression was negatively correlated with myocardial Masson’s scores (r = –0.84, P = 0.009) and left ventricular end-diastolic diameter (LVEDd; r = –0.82, P = 0.014), which might be regulated by miR-3925-5p through further bioinformatics prediction and qRT-PCR verification. The data then suggested that the metabolism-related gene OGDHL was associated with myocardial fibrosis of DCM and probably a biomarker for myocardial remodeling in patients with DCM.

A deep learning model for early risk prediction of heart failure with preserved ejection fraction by DNA methylation profiles combined with clinical features

Background

Heart failure with preserved ejection fraction (HFpEF), affected collectively by genetic and environmental factors, is the common subtype of chronic heart failure. Although the available risk assessment methods for HFpEF have achieved some progress, they were based on clinical or genetic features alone. Here, we have developed a deep learning framework, HFmeRisk, using both 5 clinical features and 25 DNA methylation loci to predict the early risk of HFpEF in the Framingham Heart Study Cohort.

Results

The framework incorporates Least Absolute Shrinkage and Selection Operator and Extreme Gradient Boosting-based feature selection, as well as a Factorization-Machine based neural network-based recommender system. Model discrimination and calibration were assessed using the AUC and Hosmer–Lemeshow test. HFmeRisk, including 25 CpGs and 5 clinical features, have achieved the AUC of 0.90 (95% confidence interval 0.88–0.92) and Hosmer–Lemeshow statistic was 6.17 (P = 0.632), which outperformed models with clinical characteristics or DNA methylation levels alone, published chronic heart failure risk prediction models and other benchmark machine learning models. Out of them, the DNA methylation levels of two CpGs were significantly correlated with the paired transcriptome levels (R < −0.3, P < 0.05). Besides, DNA methylation locus in HFmeRisk were associated with intercellular signaling and interaction, amino acid metabolism, transport and activation and the clinical variables were all related with the mechanism of occurrence of HFpEF. Together, these findings give new evidence into the HFmeRisk model.

Conclusion

Our study proposes an early risk assessment framework for HFpEF integrating both clinical and epigenetic features, providing a promising path for clinical decision making.

Integrated bioinformatic analysis reveals immune molecular markers and potential drugs for diabetic cardiomyopathy

Diabetic cardiomyopathy (DCM) is a pathophysiological condition induced by diabetes mellitus that often causes heart failure (HF). However, their mechanistic relationships remain unclear. This study aimed to identify immune gene signatures and molecular mechanisms of DCM. Microarray data from the Gene Expression Omnibus (GEO) database from patients with DCM were subjected to weighted gene co-expression network analysis (WGCNA) identify co-expression modules. Core expression modules were intersected with the immune gene database. We analyzed and mapped protein-protein interaction (PPI) networks using the STRING database and MCODE and filtering out 17 hub genes using cytoHubba software. Finally, potential transcriptional regulatory factors and therapeutic drugs were identified and molecular docking between gene targets and small molecules was performed. We identified five potential immune biomarkers: proteosome subunit beta type-8 (PSMB8), nuclear factor kappa B1 (NFKB1), albumin (ALB), endothelin 1 (EDN1), and estrogen receptor 1 (ESR1). Their expression levels in animal models were consistent with the changes observed in the datasets. EDN1 showed significant differences in expression in both the dataset and the validation model by real-time quantitative PCR (qPCR) and Western blotting(WB). Subsequently, we confirmed that the potential transcription factors upstream of EDN1 were PRDM5 and KLF4, as its expression was positively correlated with the expression of the two transcription factors. To repurpose known therapeutic drugs, a connectivity map (CMap) database was retrieved, and nine candidate compounds were identified. Finally, molecular docking simulations of the proteins encoded by the five genes with small-molecule drugs were performed. Our data suggest that EDN1 may play a key role in the development of DCM and is a potential DCM biomarker.

Metabolic Therapy of Heart Failure: Is There a Future for B Vitamins?

Heart failure (HF) is a plague of the aging population in industrialized countries that continues to cause many deaths despite intensive research into more effective treatments. Although the therapeutic arsenal to face heart failure has been expanding, the relatively short life expectancy of HF patients is pushing towards novel therapeutic strategies. Heart failure is associated with drastic metabolic disorders, including severe myocardial mitochondrial dysfunction and systemic nutrient deprivation secondary to severe cardiac dysfunction. To date, no effective therapy has been developed to restore the cardiac energy metabolism of the failing myocardium, mainly due to the metabolic complexity and intertwining of the involved processes. Recent years have witnessed a growing scientific interest in natural molecules that play a pivotal role in energy metabolism with promising therapeutic effects against heart failure. Among these molecules, B vitamins are a class of water soluble vitamins that are directly involved in energy metabolism and are of particular interest since they are intimately linked to energy metabolism and HF patients are often B vitamin deficient. This review aims at assessing the value of B vitamin supplementation in the treatment of heart failure.

Traditional Chinese medicine enhances myocardial metabolism during heart failure

The prognosis of various cardiovascular diseases eventually leads to heart failure (HF). An energy metabolism disorder of cardiomyocytes is important in explaining the molecular basis of HF; this will aid global research regarding treatment options for HF from the perspective of myocardial metabolism. There are many drugs to improve myocardial metabolism for the treatment of HF, including angiotensin receptor blocker-neprilysin inhibitor (ARNi) and sodium glucose cotransporter 2 (SGLT-2) inhibitors. Although Western medicine has made considerable progress in HF therapy, the morbidity and mortality of the disease remain high. Therefore, HF has attracted attention from researchers worldwide. In recent years, the application of traditional Chinese medicine (TCM) in HF treatment has been gradually accepted, and many studies have investigated the mechanism whereby TCM improves myocardial metabolism; the TCMs studied include Danshen yin, Fufang Danshen dripping pill, and Shenmai injection. This enables the clinical application of TCM in the treatment of HF by improving myocardial metabolism. We systematically reviewed the efficacy of TCM for improving myocardial metabolism during HF as well as the pharmacological effects of active TCM ingredients on the cardiovascular system and the potential mechanisms underlying their ability to improve myocardial metabolism. The results indicate that TCM may serve as a complementary and alternative approach for the prevention of HF. However, further rigorously designed randomized controlled trials are warranted to assess the effect of TCM on long-term hard endpoints in patients with cardiovascular disease.

Glycolysis Inhibition Alleviates Cardiac Fibrosis After Myocardial Infarction by Suppressing Cardiac Fibroblast Activation

Objective: To explore the role of glycolysis in cardiac fibroblast (CF) activation and cardiac fibrosis after myocardial infarction (MI).

Method:In vivo: 2-Deoxy-D-glucose (2-DG), a glycolysis inhibitor, was injected into the abdominal cavity of the MI or sham mice every day. On the 28th day, cardiac function was measured by ultrasonic cardiography, and the hearts were harvested. Masson staining and immunofluorescence (IF) were used to evaluate the fibrosis area, and western blot was used to identify the glycolytic level. In vitro, we isolated the CF from the sham, MI and MI with 2-DG treatment mice, and we also activated normal CF with transforming growth factor-β1 (TGF-β1) and block glycolysis with 2-DG. We then detected the glycolytic proteins, fibrotic proteins, and the concentrations of lactate and glucose in the culture medium. At last, we further detected the fibrotic and glycolytic markers in human fibrotic and non-fibrotic heart tissues with masson staining, IF and western blot.

Result: More collagen and glycolytic protein expressions were observed in the MI mice hearts. The mortality increased when mice were treated with 2-DG (100 mg/kg/d) after the MI surgery (Log-rank test, P < 0.05). When the dosage of 2-DG declined to 50 mg/kg/d, and the treatment was started on the 4th day after MI, no statistical difference of mortality between the two groups was observed (Log-rank test, P = 0.98). The collagen volume fraction was smaller and the fluorescence signal of α-smooth muscle actin (α-SMA) was weaker in mice treated with 2-DG than PBS. In vitro, 2-DG could significantly inhibit the increased expression of both the glycolytic and fibrotic proteins in the activated CF.

Conclusion: Cardiac fibrosis is along with the enhancement of CF activation and glycolysis. Glycolysis inhibition can alleviate cardiac fibroblast activation and cardiac fibrosis after myocardial infarction.

Pharmacological Tuning of Adenosine Signal Nuances Underlying Heart Failure With Preserved Ejection Fraction

Heart failure with preserved ejection fraction (HFpEF) roughly represents half of the cardiac failure events in developed countries. The proposed 'systemic microvascular paradigm' has been used to explain HFpHF presentation heterogeneity. The lack of effective treatments with few evidence-based therapeutic recommendations makes HFpEF one of the greatest unmet clinical necessities worldwide. The endogenous levels of the purine nucleoside, adenosine, increase significantly following cardiovascular events. Adenosine exerts cardioprotective, neuromodulatory, and immunosuppressive effects by activating plasma membrane-bound P1 receptors that are widely expressed in the cardiovascular system. Its proven benefits have been demonstrated in preclinical animal tests. Here, we provide a comprehensive and up-to-date critical review about the main therapeutic advantages of tuning adenosine signalling pathways in HFpEF, without discounting their side effects and how these can be seized.

Heart Metabolism in Sepsis-Induced Cardiomyopathy-Unusual Metabolic Dysfunction of the Heart

Due to the need for continuous work, the heart uses up to 8% of the total energy expenditure. Due to the relatively low adenosine triphosphate (ATP) storage capacity, the heart's work is dependent on its production. This is possible due to the metabolic flexibility of the heart, which allows it to use numerous substrates as a source of energy. Under normal conditions, a healthy heart obtains approximately 95% of its ATP by oxidative phosphorylation in the mitochondria. The primary source of energy is fatty acid oxidation, the rest of the energy comes from the oxidation of pyruvate. A failed heart is characterised by a disturbance in these proportions, with the contribution of individual components as a source of energy depending on the aetiology and stage of heart failure. A unique form of cardiac dysfunction is sepsis-induced cardiomyopathy, characterised by a significant reduction in energy production and impairment of cardiac oxidation of both fatty acids and glucose. Metabolic disorders appear to contribute to the pathogenesis of cardiac dysfunction and therefore are a promising target for future therapies. However, as many aspects of the metabolism of the failing heart remain unexplained, this issue requires further research.

Long-Term High-Fat Diet Inhibits the Recovery of Myocardial Mitochondrial Function After Chronic Hypoxia Reoxygenation in Rats

Yan, Jun, Kang Song, Sisi Zhou, and Ri-Li Ge. Long-term high-fat diet inhibits the recovery of myocardial mitochondrial function after chronic hypoxia reoxygenation in rats. High Alt Med Biol. 16:000-000, 2021. Aims: A high-fat diet (HFD) is associated with cardiovascular diseases and mitochondrial dysfunction. Obesity incidence is low at high altitudes, but the impact of HFD, which is closely associated with obesity at high altitudes, and the effects of reoxygenation on the heart are unclear. In this study, we investigated the effects of long-term HFD consumption on mitochondrial function in the myocardium after chronic hypoxia reoxygenation. Main Methods: Sprague-Dawley rats were randomized into the following six groups: normoxia groups, including a control group and HFD group; chronic hypoxia groups, including a normal chow diet (CH-CD) group and an HFD (CH-HFD) group; and hypoxic-reoxygenated (HR) groups, including a hypoxia-reoxygenation normal chow diet (HR-CD) group and a hypoxia-reoxygenation HFD (HR-HFD) group. All rats were euthanized in this study. Results: We found that chronic hypoxia aggravated myocardial mitochondrial dysfunction. The Flameng score (in which the higher the score, the more severe the mitochondrial damage) was used to assess the extent of mitochondrial structural damage. Compared with the control group and HFD group, the Flameng scores of the CH-CD and CH-HFD groups were significantly increased, respectively [1.260 ± 0.063 vs. 0.68 ± 0.05 (p < 0.05); 2.03 ± 0.07 vs. 1.48 ± 0.05 (p < 0.05)]. Moreover, progressive reoxygenation facilitated the recovery of myocardial mitochondrial function; this process was inhibited by long-term HFD. After reoxygenation, the Flameng scores in the HR-CD group became comparable to those in the CH-CD group [0.86 ± 0.05 vs. 1.26 ± 0.06 (p < 0.05)]. However, no significant changes were observed in the Flameng score between the HR-HFD and CH-HFD groups. Significance: Long-term HFD consumption inhibits myocardial mitochondrial function after reoxygenation. This finding may be helpful for the prevention and control of risk factors related to cardiovascular diseases in plateau residents.

Metabolism and Chronic Inflammation: The Links Between Chronic Heart Failure and Comorbidities

Heart failure (HF) patients often suffer from multiple comorbidities, such as diabetes, atrial fibrillation, depression, chronic obstructive pulmonary disease, and chronic kidney disease. The coexistance of comorbidities usually leads to multi morbidity and poor prognosis. Treatments for HF patients with multi morbidity are still an unmet clinical need, and finding an effective therapy strategy is of great value. HF can lead to comorbidity, and in return, comorbidity may promote the progression of HF, creating a vicious cycle. This reciprocal correlation indicates there may be some common causes and biological mechanisms. Metabolism remodeling and chronic inflammation play a vital role in the pathophysiological processes of HF and comorbidities, indicating metabolism and inflammation may be the links between HF and comorbidities. In this review, we comprehensively discuss the major underlying mechanisms and therapeutic implications for comorbidities of HF. We first summarize the potential role of metabolism and inflammation in HF. Then, we give an overview of the linkage between common comorbidities and HF, from the perspective of epidemiological evidence to the underlying metabolism and inflammation mechanisms. Moreover, with the help of bioinformatics, we summarize the shared risk factors, signal pathways, and therapeutic targets between HF and comorbidities. Metabolic syndrome, aging, deleterious lifestyles (sedentary behavior, poor dietary patterns, smoking, etc.), and other risk factors common to HF and comorbidities are all associated with common mechanisms. Impaired mitochondrial biogenesis, autophagy, insulin resistance, and oxidative stress, are among the major mechanisms of both HF and comorbidities. Gene enrichment analysis showed the PI3K/AKT pathway may probably play a central role in multi morbidity. Additionally, drug targets common to HF and several common comorbidities were found by network analysis. Such analysis has already been instrumental in drug repurposing to treat HF and comorbidity. And the result suggests sodium-glucose transporter-2 (SGLT-2) inhibitors, IL-1β inhibitors, and metformin may be promising drugs for repurposing to treat multi morbidity. We propose that targeting the metabolic and inflammatory pathways that are common to HF and comorbidities may provide a promising therapeutic strategy.

Energy metabolism disorders and potential therapeutic drugs in heart failure

Heart failure (HF) is a global public health problem with high morbidity and mortality. A large number of studies have shown that HF is caused by severe energy metabolism disorders, which result in an insufficient heart energy supply. This deficiency causes cardiac pump dysfunction and systemic energy metabolism failure, which determine the development of HF and recovery of heart. Current HF therapy acts by reducing heart rate and cardiac preload and afterload, treating the HF symptomatically or delaying development of the disease. Drugs aimed at cardiac energy metabolism have not yet been developed. In this review, we outline the main characteristics of cardiac energy metabolism in healthy hearts, changes in metabolism during HF, and related pathways and targets of energy metabolism. Finally, we discuss drugs that improve cardiac function via energy metabolism to provide new research ideas for the development and application of drugs for treating HF.

SGLT2 inhibitors break the vicious circle between heart failure and insulin resistance: targeting energy metabolism

Heart failure (HF) often coexists with insulin resistance (IR), and the incidence of HF in type 2 diabetes mellitus (T2DM) patients is significantly higher. The reciprocal relationship between HF and IR has long been recognized, and the integration complicates the therapy of both. A number of mechanisms ascribe to the progression of cardiac IR, in which the main factors are the shift of myocardial substrate metabolism. Studies have found that SGLT2 inhibitors, an anti-diabetic drug, can improve the cardiac prognosis of patients with T2DM, which may be at least partially due to the relief of cardiac IR. Basic and clinical studies have revealed the important role of cardiac IR in the pathogenesis and progression of HF, and studies suggest that energy metabolism plays an important role in the pathogenesis of cardiac IR and HF. SGLT2 inhibitors mediated cardiovascular benefits through various mechanisms such as improving substrate utilization and improving myocardial energy. The regulation of SGLT2 inhibitors on cardiac energy status including carbohydrates, fatty acids (FA), amino acids and ketones, ATP transfer to the cytoplasm, and mitochondrial functional status have received extensive attention in HF, but its specific mechanism of action is still unclear. Therefore, this article reviews the relationship between IR and HF from the perspective of energy metabolism; subsequently, targeting energy metabolism discusses the pivotal role of SGLT2 inhibitors in improving cardiac IR and HF based on basic and clinical research evidences, and sought to clarify the molecular mechanism involved. (Fig. 1).

Cardiac Connexin-43 Hemichannels and Pannexin1 Channels: Provocative Antiarrhythmic Targets

Cardiac connexin-43 (Cx43) creates gap junction channels (GJCs) at intercellular contacts and hemi-channels (HCs) at the peri-junctional plasma membrane and sarcolemmal caveolae/rafts compartments. GJCs are fundamental for the direct cardiac cell-to-cell transmission of electrical and molecular signals which ensures synchronous myocardial contraction. The HCs and structurally similar pannexin1 (Panx1) channels are active in stressful conditions. These channels are essential for paracrine and autocrine communication through the release of ions and signaling molecules to the extracellular environment, or for uptake from it. The HCs and Panx1 channel-opening profoundly affects intracellular ionic homeostasis and redox status and facilitates via purinergic signaling pro-inflammatory and pro-fibrotic processes. These conditions promote cardiac arrhythmogenesis due to the impairment of the GJCs and selective ion channel function. Crosstalk between GJCs and HCs/Panx1 channels could be crucial in the development of arrhythmogenic substrates, including fibrosis. Despite the knowledge gap in the regulation of these channels, current evidence indicates that HCs and Panx1 channel activation can enhance the risk of cardiac arrhythmias. It is extremely challenging to target HCs and Panx1 channels by inhibitory agents to hamper development of cardiac rhythm disorders. Progress in this field may contribute to novel therapeutic approaches for patients prone to develop atrial or ventricular fibrillation.

Inhibition of angiotensin II-induced hypertrophy and cardiac dysfunction by North American ginseng (Panax quinquefolius)

We determined whether North American ginseng (Panax quinquefolius L.) mitigates the effect of angiotensin II on hypertrophy and heart failure. Angiotensin II (0.3 mg/kg) was administered to rats for 2 or 4 weeks in the presence or absence of ginseng pretreatment. The effect of ginseng (10 μg/mL) on angiotensin II (100 nM) - induced hypertrophy was also determined in neonatal rat ventricular myocytes. We also determined effects of ginseng on fatty acid and glucose oxidation by measuring gene and protein expression levels of key factors. Angiotensin II treatment for 2 and 4 weeks induced cardiac hypertrophy as evidenced by increased heart weights, as well as the upregulation of the hypertrophy-related fetal gene expression levels, with all effects being abolished by ginseng. Ginseng also reduced abnormalities in left ventricular function as well as the angiotensin II-induced increased blood pressure. In myocytes, ginseng abolished the hypertrophic response to angiotensin II as assessed by surface area and gene expression of molecular markers of hypertrophy. Ginseng modulated angiotensin II-induced abnormalities in gene expression and protein levels of CD36, CPT1M, Glut4, and PDK4 in vivo and in vitro. In conclusion, ginseng suppresses angiotensin II-induced cardiac hypertrophy and dysfunction which is related to normalization of fatty acid and glucose oxidation.

Solute Carrier Transporters as Potential Targets for the Treatment of Metabolic Disease

The solute carrier (SLC) superfamily comprises more than 400 transport proteins mediating the influx and efflux of substances such as ions, nucleotides, and sugars across biological membranes. Over 80 SLC transporters have been linked to human diseases, including obesity and type 2 diabetes (T2D). This observation highlights the importance of SLCs for human (patho)physiology. Yet, only a small number of SLC proteins are validated drug targets. The most recent drug class approved for the treatment of T2D targets sodium-glucose cotransporter 2, product of the SLC5A2 gene. There is great interest in identifying other SLC transporters as potential targets for the treatment of metabolic diseases. Finding better treatments will prove essential in future years, given the enormous personal and socioeconomic burden posed by more than 500 million patients with T2D by 2040 worldwide. In this review, we summarize the evidence for SLC transporters as target structures in metabolic disease. To this end, we identified SLC13A5/sodium-coupled citrate transporter, and recent proof-of-concept studies confirm its therapeutic potential in T2D and nonalcoholic fatty liver disease. Further SLC transporters were linked in multiple genome-wide association studies to T2D or related metabolic disorders. In addition to presenting better-characterized potential therapeutic targets, we discuss the likely unnoticed link between other SLC transporters and metabolic disease. Recognition of their potential may promote research on these proteins for future medical management of human metabolic diseases such as obesity, fatty liver disease, and T2D. SIGNIFICANCE STATEMENT: Given the fact that the prevalence of human metabolic diseases such as obesity and type 2 diabetes has dramatically risen, pharmacological intervention will be a key future approach to managing their burden and reducing mortality. In this review, we present the evidence for solute carrier (SLC) genes associated with human metabolic diseases and discuss the potential of SLC transporters as therapeutic target structures.

Qiliqiangxin Capsules Optimize Cardiac Metabolism Flexibility in Rats With Heart Failure After Myocardial Infarction

Metabolic modulation is a promising therapy for ischemic heart disease and heart failure. This study aimed to clarify the regional modulatory effect of Qiliqiangxin capsules (QLQX), a traditional Chinese medicine, on cardiac metabolic phenotypes. Sprague-Dawley rats underwent left anterior descending coronary artery ligation and were treated with QLQX and enalapril. Striking global left ventricular dysfunction and left ventricular remodeling were significantly improved by QLQX. In addition to the posterior wall, QLQX also had a unique beneficial effect on the anterior wall subject to a severe oxygen deficit. Cardiac tissues in the border and remote areas were separated for detection. QLQX enhanced the cardiac ¹⁸F-fluorodeoxyglucose uptake and the levels and translocation of glucose transport 4 (GLUT4) in the border area. Meanwhile, it also suppressed glucose transport 1 (GLUT1) in both areas, indicating that QLQX encouraged border myocytes to use more glucose in a GLUT4-dependent manner. It was inferred that QLQX promoted a shift from glucose oxidation to anaerobic glycolysis in the border area by the augmentation of phosphorylated pyruvate dehydrogenase, pyruvate dehydrogenase kinases 4, and lactic dehydrogenase A. QLQX also upregulated the protein expression of fatty acid translocase and carnitine palmitoyl transferase-1 in the remote area to possibly normalize fatty acid (FA) uptake and oxidation similar to that in healthy hearts. QLQX protected global viable cardiomyocytes and promoted metabolic flexibility by modulating metabolic proteins regionally, indicating its potential for driving the border myocardium into an anaerobic glycolytic pathway against hypoxia injuries and urging the remote myocardium to oxidize FA to maximize energy production.

Metabolomic Profile in HFpEF vs HFrEF Patients

BACKGROUND

Heart failure with preserved ejection fraction (HFpEF) and HF with reduced ejection fraction (HFrEF) are associated with metabolic derangements, which may have different pathophysiological implications.

METHODS AND RESULTS

In new-onset HFpEF (EF of ≥50%, n = 46) and HFrEF (EF of <40%, n = 75) patients, 109 endogenous plasma metabolites including amino acids, phospholipids and acylcarnitines were assessed using targeted metabolomics. Differentially altered metabolites and associations with clinical characteristics were explored. Patients with HFpEF were older, more often female with hypertension, atrial fibrillation, and diabetes compared with patients with HFrEF. Patients with HFpEF displayed higher levels of hydroxyproline and symmetric dimethyl arginine, alanine, cystine, and kynurenine reflecting fibrosis, inflammation and oxidative stress. Serine, cGMP, cAMP, l-carnitine, lysophophatidylcholine (18:2), lactate, and arginine were lower compared with patients with HFrEF. In patients with HFpEF with diabetes, kynurenine was higher (P = .014) and arginine lower (P = .014) vs patients with no diabetes, but did not differ with diabetes status in HFrEF. Decreasing kynurenine was associated with higher eGFR only in HFpEF (P_interaction = .020).

CONCLUSIONS

Patients with new-onset HFpEF compared with patients with new-onset HFrEF display a different metabolic profile associated with comorbidities, such as diabetes and kidney dysfunction. HFpEF is associated with indices of increased inflammation and oxidative stress, impaired lipid metabolism, increased collagen synthesis, and downregulated nitric oxide signaling. Together, these findings suggest a more predominant systemic microvascular endothelial dysfunction and inflammation linked to increased fibrosis in HFpEF compared with HFrEF.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov NCT03671122 https://clinicaltrials.gov.

Deficiency of bone morphogenetic protein-3b induces metabolic syndrome and increases adipogenesis

Bone morphogenetic protein (BMP) receptor signaling is critical for the regulation of the endocrine system and cardiovascular structure and function. The objective of this study was to investigate whether Bmp3b, a glycoprotein synthetized and secreted by adipose tissue, is necessary to regulate glucose and lipid metabolism, adipogenesis, and cardiovascular remodeling. Over the course of 4 mo, Bmp3b-knockout (Bmp3b^-/-) mice gained more weight than wild-type (WT) mice. The plasma levels of cholesterol and triglycerides were higher in Bmp3b^-/- mice than in WT mice. Bmp3b^-/- mice developed insulin resistance and glucose intolerance. The basal heart rate was higher in Bmp3b^-/- mice than in WT mice, and echocardiography revealed eccentric remodeling in Bmp3b^-/- mice. The expression of adipogenesis-related genes in white adipose tissue was higher in Bmp3b^-/- mice than in WT control mice. In vitro studies showed that Bmp3b modulates the activity of the C/ebpα promoter, an effect mediated by Smad2/3. The results of this study suggest that Bmp3b is necessary for the maintenance of homeostasis in terms of age-related weight gain, glucose metabolism, and left ventricular (LV) remodeling and function. Interventions that increase the level or function of BMP3b may decrease cardiovascular risk and pathological cardiac remodeling.

Inhibition of P2X7 Purinergic Receptor Ameliorates Cardiac Fibrosis by Suppressing NLRP3/IL-1β Pathway

P2X7 purinergic receptor (P2X7R) has been implicated in several cardiovascular diseases. However, whether it regulates cardiac fibrosis remains elusive. Herein, its involvement in the development of cardiac fibrosis was examined using a transverse aortic constriction (TAC) mice model and cardiac fibroblasts (CFs) hyperstimulated by TGF-β1 for 48 hours. Results showed that TAC and TGF-β1 treatment increased the expression of P2X7R. Silencing of P2X7R expression with siP2X7R ameliorated TGF-β1 effects on fibroblasts activation. Similarly, P2X7R inhibition by Brilliant Blue G (BBG) reduced mRNA and protein levels of profibrosis markers, while the P2X7R agonist BzATP accelerated the TGF-β1-induced CFs activation. Moreover, it was found that TGF-β1-induced CFs activation was mediated by the NLRP3/IL-1β inflammasome pathway. BBG or siP2X7R treatment suppressed NLRP3/IL-1β pathway signaling. In vivo, BBG significantly alleviated TAC-induced cardiac fibrosis, cardiac dysfunction, and NLRP3/IL-1β activation. Collectively, our findings imply that suppressing P2X7R may limit cardiac fibrosis and abnormal activation of CFs.

Shenmai Injection Improves Energy Metabolism in Patients With Heart Failure: A Randomized Controlled Trial

Background

In recent years, the application of Shenmai (SM) injection, a traditional Chinese medicine (TCM), to treat heart failure (HF) has been gradually accepted in China. However, whether SM improves energy metabolism in patients with HF has not been determined due to the lack of high-quality studies. We aimed to investigate the influence of SM on energy metabolism in patients with HF.

Methods

This single-blind, controlled study randomly assigned 120 eligible patients equally into three groups receiving SM, trimetazidine (TMZ), or control in addition to standard medical treatment for HF for 7 days. The primary endpoints were changes in free fatty acids (FFAs), glucose, lactic acid (LA), pyroracemic acid (pyruvate, PA) and branched chain amino acids (BCAAs) in serum. The secondary outcomes included the New York Heart Association (NYHA) functional classification, TCM syndrome score (TCM-s), left ventricular injection fraction (LVEF), left ventricular internal diastolic diameter (LVIDd), left ventricular internal dimension systole (LVIDs), and B-type natriuretic peptide (BNP).

Results

After treatment for 1 week, the NYHA functional classification, TCM-s, and BNP level gradually decreased in the patients in all three groups, but these metrics were significantly increased in the patients in the SM group compared with those in the patients in the TMZ and control groups (P < 0.05). Moreover, energy metabolism was improved in the NYHA III–IV patients in the SM group compared with those in the patients in the TMZ and control groups as evidenced by changes in the serum levels of FFA, LA, PA, and BCAA.

Conclusions

Integrative treatment with SM in addition to standard medical treatment for HF was associated with improved cardiac function compared to standard medical treatment alone. The benefit of SM in HF may be related to an improvement in energy metabolism, which seems to be more remarkable than that following treatment with TMZ.

Integrated UPLC-Q/TOF-MS Technique and MALDI-MS to Study of the Efficacy of YiXinshu Capsules Against Heart Failure in a Rat Model

Background: Yixinshu Capsules (YXSC) are widely used in Chinese medicine for the treatment of cardiovascular diseases. However, the therapeutic mechanisms of action are not well understood.

Method: In this study, a metabonomic approach based on integrated UPLC-Q/TOF-MS technique and MALDI-MS was utilized to explore potential metabolic biomarkers that may help increase the understanding of heart failure (HF) and in order to assess the potential mechanisms of YXSC against HF. Plasma metabolic profiles were analyzed by UPLC-Q/TOF-MS with complementary hydrophilic interaction chromatography and reversed-phase liquid chromatography. Moreover, time-course analysis at the 2nd, 4th, and 10th week after permanent occlusion was conducted. In an effort to identify a more reliable potential metabolic marker, common metabolic markers of the 2nd, 4th, and 10th week were selected through multivariate data analysis. Furthermore, MALDI-MS was applied to identify metabolic biomarkers in the blood at apoptotic positions of heart tissues.

Results: The results showed that HF appeared at the fourth week after permanent occlusion based on echocardiographic assessment. Clear separations were observed between the sham and model group by loading plots of orthogonal projection to latent structure discrimination analysis (OPLS-DA) at different time points after permanent occlusion. Potential markers of interest were extracted from the combining S-plots, variable importance for the projections values (VIP > 1), and t-test (p < 0.05). Twenty-one common metabolic markers over the course of the development and progression of HF after permanent occlusion were identified. These were determined to be mainly related to disturbances in fatty acids, phosphatidylcholine, bile acids, amino acid metabolism, and pyruvate metabolism. Of the metabolic markers, 16 metabolites such as palmitoleic acid, arachidonic acid, and lactic acid showed obvious changes (p < 0.05) and a tendency for returning to baseline values in YXSC-treated HF rats at the 10th week. Moreover, four biomarkers, including palmitoleic acid, palmitic acid, arachidonic, acid and lactic acid, were further validated at the apoptotic position of heart tissue using MALDI-MS, consistent to the variation trends in the plasma.

Conclusions: Taken in concert, our proposed strategy may contribute to the understanding of the complex pathogenesis of ischemia-induced HF and the potential mechanism of YXSC.