Myocardial substrate metabolism in the normal and failing heart

A stratified study of human blood metabolites and coronary artery diseases-A Mendelian randomization study

BACKGROUND AND AIMS

Metabolic dysregulation is closely associated with coronary artery diseases (CAD). Exploring the relationship between metabolites and CAD is helpful in identifying changes in energy metabolism during disease progression.

METHODS AND RESULTS

We use Mendelian Randomization (MR) analysis to assess the relationships between 275 serum metabolites and CAD such as angina pectoris, post-myocardial infarction complications, coronary atherosclerosis, myocardial infarction (MI), and unstable angina pectoris (UA). The inverse variance-weighted method (IVW) served as the primary approach for causal analysis, with MR-Egger and weighted median (WM) as supplementary methods. Sensitivity analyses were conducted to assess heterogeneity and multiple effects. We also analyzed potentially related metabolic pathways.We identified causal relationships between 42 known metabolites and CAD. Among them, the genetic susceptibility to elevated levels of amino acid Isobutyrylcarnitine is associated with an increased risk of coronary artery atherosclerosis; but it provides protection against the development of MI. Genetic susceptibility to elevated levels of fatty acids Stearate, Caprylate is associated with higher risk of angina pectoris, while Threonate has a protective effect in the development of angina; Stearate is associated with an increased risk of UA, whereas higher levels of the lipids Choline, 1-arachidonoylglycerophosphoinositol∗, Hexadecanedioate, Tetradecanedioate play a protective role in UA.Metabolic pathway analysis identified 6 pathways that may be associated with CAD.

CONCLUSION

We identified causal relationships between 42 serum metabolites and CAD. Specifically, changes in metabolites such as Isobutyrylcarnitine, Caprylate, and Stearate were associated with risks of CAD. These findings provide new insights into the metabolic mechanisms of CAD.

Proteomic and metabolomic analyses of the human adult myocardium reveal ventricle-specific regulation in end-stage cardiomyopathies

The left and right ventricles of the human heart are functionally and developmentally distinct such that genetic or acquired insults can cause dysfunction in one or both ventricles resulting in heart failure. To better understand ventricle-specific molecular changes influencing heart failure development, we first performed unbiased quantitative mass spectrometry on pre-mortem non-diseased human myocardium to compare the metabolome and proteome between the normal left and right ventricles. Constituents of gluconeogenesis, glycolysis, lipogenesis, lipolysis, fatty acid catabolism, the citrate cycle and oxidative phosphorylation were down-regulated in the left ventricle, while glycogenesis, pyruvate and ketone metabolism were up-regulated. Inter-ventricular significance of these metabolic pathways was then found to be diminished within end-stage dilated cardiomyopathy and ischaemic cardiomyopathy, while heart failure-associated pathways were increased in the left ventricle relative to the right within ischaemic cardiomyopathy, such as fluid sheer-stress, increased glutamine-glutamate ratio, and down-regulation of contractile proteins, indicating a left ventricular pathological bias.

SGLT2 inhibition alters substrate utilization and mitochondrial redox in healthy and failing rat hearts

Previous studies highlight the potential for sodium-glucose cotransporter type 2 (SGLT2) inhibitors (SGLT2i) to exert cardioprotective effects in heart failure by increasing plasma ketones and shifting myocardial fuel utilization toward ketone oxidation. However, SGLT2i have multiple in vivo effects and the differential impact of SGLT2i treatment and ketone supplementation on cardiac metabolism remains unclear. Here, using gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) methodology combined with infusions of [13C6]glucose or [13C4]βOHB, we demonstrate that acute SGLT2 inhibition with dapagliflozin shifts relative rates of myocardial mitochondrial metabolism toward ketone oxidation, decreasing pyruvate oxidation with little effect on fatty acid oxidation in awake rats. Shifts in myocardial ketone oxidation persisted when plasma glucose levels were maintained. In contrast, acute βOHB infusion similarly augmented ketone oxidation, but markedly reduced fatty acid oxidation and did not alter glucose uptake or pyruvate oxidation. After inducing heart failure, dapagliflozin increased relative rates of ketone and fatty acid oxidation, but decreased pyruvate oxidation. Dapagliflozin increased mitochondrial redox and reduced myocardial oxidative stress in heart failure, which was associated with improvements in left ventricular ejection fraction after 3 weeks of treatment. Thus, SGLT2i have pleiotropic effects on systemic and heart metabolism, which are distinct from ketone supplementation and may contribute to the long-term cardioprotective benefits of SGLT2i.

Advances in myocardial energy metabolism: metabolic remodelling in heart failure and beyond

The very high energy demand of the heart is primarily met by adenosine triphosphate (ATP) production from mitochondrial oxidative phosphorylation, with glycolysis providing a smaller amount of ATP production. This ATP production is markedly altered in heart failure, primarily due to a decrease in mitochondrial oxidative metabolism. Although an increase in glycolytic ATP production partly compensates for the decrease in mitochondrial ATP production, the failing heart faces an energy deficit that contributes to the severity of contractile dysfunction. The relative contribution of the different fuels for mitochondrial ATP production dramatically changes in the failing heart, which depends to a large extent on the type of heart failure. A common metabolic defect in all forms of heart failure [including heart failure with reduced ejection fraction (HFrEF), heart failure with preserved EF (HFpEF), and diabetic cardiomyopathies] is a decrease in mitochondrial oxidation of pyruvate originating from glucose (i.e. glucose oxidation). This decrease in glucose oxidation occurs regardless of whether glycolysis is increased, resulting in an uncoupling of glycolysis from glucose oxidation that can decrease cardiac efficiency. The mitochondrial oxidation of fatty acids by the heart increases or decreases, depending on the type of heart failure. For instance, in HFpEF and diabetic cardiomyopathies myocardial fatty acid oxidation increases, while in HFrEF myocardial fatty acid oxidation either decreases or remains unchanged. The oxidation of ketones (which provides the failing heart with an important energy source) also differs depending on the type of heart failure, being increased in HFrEF, and decreased in HFpEF and diabetic cardiomyopathies. The alterations in mitochondrial oxidative metabolism and glycolysis in the failing heart are due to transcriptional changes in key enzymes involved in the metabolic pathways, as well as alterations in redox state, metabolic signalling and post-translational epigenetic changes in energy metabolic enzymes. Of importance, targeting the mitochondrial energy metabolic pathways has emerged as a novel therapeutic approach to improving cardiac function and cardiac efficiency in the failing heart.

CRISPRi/a screens in human iPSC-cardiomyocytes identify glycolytic activation as a druggable target for doxorubicin-induced cardiotoxicity

Doxorubicin is limited in its therapeutic utility due to its life-threatening cardiovascular side effects. Here, we present an integrated drug discovery pipeline combining human induced pluripotent stem cell (iPSC)-derived cardiomyocytes (iCMs), CRISPR interference and activation (CRISPRi/a) bidirectional pooled screens, and a small-molecule screening to identify therapeutic targets mitigating doxorubicin-induced cardiotoxicity (DIC) without compromising its oncological effects. The screens revealed several previously unreported candidate genes contributing to DIC, including carbonic anhydrase 12 (CA12). Genetic inhibition of CA12 protected iCMs against DIC by improving cell survival, sarcomere structural integrity, contractile function, and calcium handling. Indisulam, a CA12 antagonist, can effectively attenuate DIC in iCMs, engineered heart tissue, and animal models. Mechanistically, doxorubicin-induced CA12 potentiated a glycolytic activation in cardiomyocytes, contributing to DIC by interfering with cellular metabolism and functions. Collectively, our study provides a roadmap for future drug discovery efforts, potentially leading to more targeted therapies with minimal off-target toxicity.

Huangqi-Danshen decoction improves heart failure by regulating pericardial adipose tissue derived extracellular vesicular miR-27a-3p to activate AMPKα2 mediated mitophagy

BACKGROUND

Huangqi-Danshen decoction (HDD) is a classic traditional Chinese medicine for treating heart failure. Pericardial adipose tissue (PAT) has recently gained increasing attention in cardiovascular diseases.

PURPOSE

This study aimed to investigate the effect of pericardial adipose tissue-derived extracellular vesicles on heart failure, the protective effect of HDD on myocardial remodel in heart failure rats, and identify the potential molecular mechanisms involved.

METHODS

UPLC-MS/MS identified active components of HDD. Extracellular vesicles (EVs) from pericardial adipose tissue of sham-operated and HF rats were identified through transmission electron microscopy, nanoparticle tracking analysis and western blot. EVs were co-cultured with H9c2 cardiomyocytes in order to examine their uptake and effects. MicroRNA sequencing, dual-luciferase reporter assay and PCR were conducted for exploring specific mechanisms of EVs on hypertrophic cardiomyocytes. In vivo, heart failure was modeled in rats via transverse aortic constriction (TAC). In vitro, the hypertrophic cardiomyocyte model were established using Ang II-induced H9c2 cardiomyocytes.

RESULTS

UPLC-MS/MS identified 11 active components in serum of HDD administrated rats. Echocardiography showed HDD improved cardiac function in TAC model rats. HE and Masson staining indicated HDD ameliorated myocardial hypertrophy and fibrosis. MicroRNA sequencing found that HDD treatment resulted in 37 differentially expressed miRNAs (DMEs) (p < 0.05 and |log2FC| ≥ 1). KEGG analysis revealed that DEMs were enriched in the AMPK signaling pathway. PCR identified miR-27a-3p with the greatest difference in AMPK-related DMEs. Dual-luciferase reporter assay and Targetscan website were utilized to identify the target relationship between miR-27a-3p and PRKAA2 (AMPKα2). The miR-27a-3p negatively regulated AMPKα2 to inhibit mitophagy mediated by PINK1/Parkin pathway. HDD inhibited miR-27a-3p secretion from failing heart pericardial adipose tissue-derived extracellular vesicles, thereby improving inflammation, cardiac function, and myocardial remodeling through above pathways.

CONCLUSION

HDD inhibited the PAT-derived extracellular vesicular miR-27a-3p in failing hearts to activate AMPK/PINK1/Parkin signaling-mediated mitophagy, which improved cardiomyocyte energy metabolism, myocardial remodeling and heart failure.

Nitric oxide and mitochondrial function in cardiovascular diseases

Nitric oxide (NO) has been highlighted as an important factor in cardiovascular system. As a signaling molecule in the cardiovascular system, NO can relax blood vessels, lower blood pressure, and prevent platelet aggregation. Mitochondria serve as a central hub for cellular metabolism and intracellular signaling, and their dysfunction can lead to a variety of diseases. Accumulating evidence suggests that NO can act as a regulator of mitochondria, affecting mitochondrial function and cellular activity, which in turn mediates the onset and progression of disease. However, there is a lack of comprehensive understanding of how NO regulates mitochondrial function in the cardiovascular system. This review aims to summarize the regulation of mitochondrial function by nitric oxide in cardiovascular related diseases, as well as the multifaceted and complex roles of NO in the cardiovascular system. Understanding the mechanism of NO mediated mitochondrial function can provide new insights for the prevention and treatment of cardiovascular diseases.

Proteomic and ubiquitinome analysis reveal that microgravity affects glucose metabolism of mouse hearts by remodeling non-degradative ubiquitination

Long-term exposure to a microgravity environment leads to structural and functional changes in hearts of astronauts. Although several studies have reported mechanisms of cardiac damage under microgravity conditions, comprehensive research on changes at the protein level in these hearts is still lacking. In this study, proteomic analysis of microgravity-exposed hearts identified 156 differentially expressed proteins, and ubiquitinomic analysis of these hearts identified 169 proteins with differential ubiquitination modifications. Integrated ubiquitinomic and proteomic analysis revealed that differential proteomic changes caused by transcription affect the immune response in microgravity-exposed hearts. Additionally, changes in ubiquitination modifications under microgravity conditions excessively activated certain kinases, such as hexokinase and phosphofructokinase, leading to cardiac metabolic disorders. These findings provide new insights into the mechanisms of cardiac damage under microgravity conditions.

Effects of In Ovo Taurine Injection on Embryo Development, Antioxidant Status, and Bioactive Peptide Content in Chicken Embryos (Gallus gallus domesticus)

Stress in birds disrupts the homeostasis of the organism, leading to an inability to neutralize reactive oxygen species. Taurine, an effective antioxidant, affects various cellular mechanisms, including cation modulation, protein phosphorylation, and cell proliferation. The aim of the study was to evaluate the effect of colloid with taurine applied in ovo to Albumin on embryonic development, oxidative stress indicators and the content of bioactive peptides-carnosine and anserine-in the pectoral muscle. The research materials were eggs of the parent flock (Ross 308) divided into four groups (K (without injection), T50-concentration of taurine hydrocolloid 50 ppm (mg/L); T100-colloid concentration 100 ppm (mg/L) taurine; T500-colloid concentration of 500 ppm (mg/L) taurine). The experimental solutions were injected in an amount of 0.3 mL into egg white. Eggs were incubated under standard incubation conditions. The addition of 100 and 500 ppm taurine had a highly significant (p = 0.001) effect on the plasma antioxidant potential in chicks. The level of anserine increased with increasing concentrations of taurine. These changes were highly significant (p = 0.007). The level of anserine in the T2 and T3 groups was determined to be 2.5 times higher than in the pectoral muscles of embryos not treated with taurine colloid. An analysis of the results showed that the administration of an increased dose of hydrocolloid with taurine increased the content of carnosine and anserine in the pectoral muscle. Colloid with taurine applied in ovo to chicken white egg reduces oxidative stress and increases homeostasis of the organism.

Reduced in utero substrate supply decreases mitochondrial abundance and alters the expression of metabolic signalling molecules in the fetal sheep heart

Babies born with fetal growth restriction (FGR) are at higher risk of developing cardiometabolic diseases across the life course. The reduction in substrate supply to the developing fetus that causes FGR not only alters cardiac growth and structure but may have deleterious effects on metabolism and function. Using a sheep model of placental restriction to induce FGR, we investigated key cardiac metabolic and functional markers that may be altered in FGR. We also employed phase-contrast magnetic resonance imaging MRI to assess left ventricular cardiac output (LVCO) as a measure of cardiac function. We hypothesized that signalling molecules involved in cardiac fatty acid utilisation and contractility would be impaired by FGR and that this would have a negative impact on LVCO in the late gestation fetus. Key glucose (GLUT4 protein) and fatty acid (FATP, CD36 gene expression) substrate transporters were significantly reduced in the hearts of FGR fetuses. We also found reduced mitochondrial numbers as well as abundance of electron transport chain complexes (complexes II and IV). These data suggest that FGR diminishes metabolic and mitochondrial capacity in the fetal heart; however, alterations were not correlated with fetal LVCO. Overall, these data show that FGR alters fetal cardiac metabolism in late gestation. If sustained ex utero, this altered metabolic profile may contribute to poor cardiac outcomes in FGR-born individuals after birth. KEY POINTS: Around the time of birth, substrate utilisation in the fetal heart switches from carbohydrates to fatty acids. However, the effect of fetal growth restriction (FGR) on this switch, and thus the ability of the fetal heart to effectively metabolise fatty acids, is not fully understood. Using a sheep model of early onset FGR, we observed significant downregulation in mRNA expression of fatty acid receptors CD36 and FABP in the fetal heart. FGR fetuses also had significantly lower cardiac mitochondrial abundance than controls. There was a reduction in abundance of complexes II and IV within the electron transport chain of the FGR fetal heart, suggesting altered ATP production. This indicates reduced fatty acid metabolism and mitochondrial function in the heart of the FGR fetus, which may have detrimental long-term implications and contribute to increased risk of cardiovascular disease later in life.

Compartmentalization in cardiomyocytes modulates creatine kinase and adenylate kinase activities

Intracellular molecules are transported by motor proteins or move by diffusion resulting from random molecular motion. Cardiomyocytes are packed with structures that are crucial for function, but also confine the diffusional spaces, providing cells with a means to control diffusion. They form compartments in which local concentrations are different from the overall, average concentrations. For example, calcium and cyclic AMP are highly compartmentalized, allowing these versatile second messengers to send different signals depending on their location. In energetic compartmentalization, the ratios of AMP and ADP to ATP are different from the average ratios. This is important for the performance of ATPases fuelling cardiac excitation-contraction coupling and mechanical work. A recent study suggested that compartmentalization modulates the activity of creatine kinase and adenylate kinase in situ. This could have implications for energetic signaling through, for example, AMP-activated kinase. It highlights the importance of taking compartmentalization into account in our interpretation of cellular physiology and developing methods to assess local concentrations of AMP and ADP to enhance our understanding of compartmentalization in different cell types.

A novel 3D imaging approach for quantification of GLUT4 levels across the intact myocardium

Cellular heterogeneity is a well-accepted feature of tissues, and both transcriptional and metabolic diversity have been revealed by numerous approaches, including optical imaging. However, the high magnification objective lenses needed for high-resolution imaging provides information from only small layers of tissue, which can result in poor cell statistics. There is therefore an unmet need for an imaging modality that can provide detailed molecular and cellular insight within intact tissue samples in 3D. Using GFP-tagged GLUT4 as proof of concept, we present here a novel optical mesoscopy approach that allows precise measurement of the spatial location of GLUT4 within specific anatomical structures across the myocardium in ultrathick sections (5 mm×5 mm×3 mm) of intact mouse heart. We reveal distinct GLUT4 distribution patterns across cardiac walls and highlight specific changes in GLUT4 expression levels in response to high fat diet-feeding, and we identify sex-dependent differences in expression patterns. This method is applicable to any target that can be labelled for light microscopy, and to other complex tissues when organ structure needs to be considered simultaneously with cellular detail.

Multifaceted Impact of SGLT2 Inhibitors in Heart Failure Patients: Exploring Diverse Mechanisms of Action

Heart failure (HF) is a growing concern due to the aging population and increasing prevalence of comorbidities. Despite advances in treatment, HF remains a significant burden, necessitating novel therapeutic approaches. Sodium-glucose cotransporter 2 inhibitors (SGLT2is) have emerged as a promising treatment option, demonstrating benefits across the entire spectrum of HF, regardless of left ventricular ejection fraction (LVEF). This review explores the multifaceted mechanisms through which SGLT2is exert cardioprotective effects, including modulation of energy metabolism, reduction of oxidative stress, attenuation of inflammation, and promotion of autophagy. SGLT2is shift myocardial energy substrate utilization from carbohydrates to more efficient fatty acids and ketone bodies, enhancing mitochondrial function and reducing insulin resistance. These inhibitors also mitigate oxidative stress by improving mitochondrial biogenesis, reducing reactive oxygen species (ROS) production, and regulating calcium-signaling pathways. Inflammation, a key driver of HF progression, is alleviated through the suppression of proinflammatory cytokines and modulation of immune cell activity. Additionally, SGLT2is promote autophagy, facilitating the clearance of damaged cellular components and preserving myocardial structure and function. Beyond their glucose-lowering effects, SGLT2is provide significant benefits in patients with chronic kidney disease (CKD) and HF, reducing the progression of CKD and improving overall survival. The pleiotropic actions of SGLT2is highlight their potential as a cornerstone in HF management. Further research is needed to fully elucidate their mechanisms and optimize their use in clinical practice.

Cardiac Aging in the Multi-Omics Era: High-Throughput Sequencing Insights

Cardiovascular diseases are a leading cause of mortality worldwide, and the risks of both developing a disease and receiving a poor prognosis increase with age. With increasing life expectancy, understanding the mechanisms underlying heart aging has become critical. Traditional techniques have supported research into finding the physiological changes and hallmarks of cardiovascular aging, including oxidative stress, disabled macroautophagy, loss of proteostasis, and epigenetic alterations, among others. The advent of high-throughput multi-omics techniques offers new perspectives on the molecular mechanisms and cellular processes in the heart, guiding the development of therapeutic targets. This review explores the contributions and characteristics of these high-throughput techniques to unraveling heart aging. We discuss how different high-throughput omics approaches, both alone and in combination, produce robust and exciting new findings and outline future directions and prospects in studying heart aging in this new era.

A simulation study on the role of mitochondria-sarcoplasmic reticulum Ca2+ interaction in cardiomyocyte energetics during exercise

Previous studies demonstrated that the mitochondrial Ca2+ uniporter MCU and the Na+-Ca2+ exchanger NCLX exist in proximity to the sarcoplasmic reticulum (SR) ryanodine receptor RyR and the Ca2+ pump SERCA, respectively, creating a mitochondria-SR Ca2+ interaction. However, the physiological relevance of the mitochondria-SR Ca2+ interaction has remained unsolved. Furthermore, although mitochondrial Ca2+ has been proposed to be an important factor regulating mitochondrial energy metabolism, by activating NADH-producing dehydrogenases, the contribution of the Ca2+-dependent regulatory mechanisms to cellular functions under physiological conditions has been controversial. In this study, we constructed a new integrated model of human ventricular myocyte with excitation-contraction-energetics coupling and investigated systematically the contribution of mitochondria-SR Ca2+ interaction, especially focusing on cardiac energetics during dynamic workload transitions in exercise. Simulation analyses revealed that the spatial coupling of mitochondria and SR, particularly via mitochondrial Ca2+ uniport activity-RyR, was the primary determinant of mitochondrial Ca2+ concentration, and that the Ca2+-dependent regulatory mechanism facilitated mitochondrial NADH recovery during exercise and contributed to the stability of NADH in the workload transition by about 40%, while oxygen consumption rate and cytoplasmic ATP level were not influenced. We concluded that the mitochondria-SR Ca2+ interaction, created via the uneven distribution of Ca2+ handling proteins, optimizes the contribution of the mitochondrial Ca2+-dependent regulatory mechanism to stabilizing NADH during exercise. KEY POINTS: The mitochondrial Ca2+ uniporter protein MCU and the Na+-Ca2+ exchanger protein NCLX are reported to exist in proximity to the sarcoplasmic reticulum (SR) ryanodine receptor RyR and the Ca2+ pump SERCA, respectively, creating a mitochondria-SR Ca2+ interaction in cardiomyocytes. Mitochondrial Ca2+ (Ca2+ mit) has been proposed to be an important factor regulating mitochondrial energy metabolism, by activating NADH-producing dehydrogenases. Here we constructed an integrated model of a human ventricular myocyte with excitation-contraction-energetics coupling and investigated the role of the mitochondria-SR Ca2+ interaction in cardiac energetics during exercise. Simulation analyses revealed that the spatial coupling particularly via mitochondrial Ca2+ uniport activity-RyR is the primary determinant of Ca2+ mit concentration, and that the activation of NADH-producing dehydrogenases by Ca2+ mit contributes to NADH stability during exercise. The mitochondria-SR Ca2+ interaction optimizes the contribution of Ca2+ mit to the activation of NADH-producing dehydrogenases.

Mitochondrial non-energetic function and embryonic cardiac development

The initial contraction of the heart during the embryonic stage necessitates a substantial energy supply, predominantly derived from mitochondrial function. However, during embryonic heart development, mitochondria influence beyond energy supplementation. Increasing evidence suggests that mitochondrial permeability transition pore opening and closing, mitochondrial fusion and fission, mitophagy, reactive oxygen species production, apoptosis regulation, Ca2+ homeostasis, and cellular redox state also play critical roles in early cardiac development. Therefore, this review aims to describe the essential roles of mitochondrial non-energetic function embryonic cardiac development.

Fat Embolism Does Not Alter Cardiac Structure or Induce Pathological Changes in a Rat Model

INTRODUCTION

Fat embolism (FE) encompasses conditions in which fatty substance becomes embedded in a tissue/organ. Fat emboli most commonly affect the lungs in a trauma setting. This can lead to both significant pathology locally and systemically including changes in structure, inflammatory response, activation of the renin-angiotensin system, and subsequent hypoxia. In fact, changes in skin, brain, lungs, and kidneys have been noted in FE syndrome. Because there is an extensive record of pathology reports on this condition without evidence of direct cardiac involvement, as well as our studies showing apparent complete recovery after the acute embolism, we hypothesized that structural changes similar to the lung and at the same time course would not be observed in the heart.

METHODS

We used a rat model of FE previously described by our group where we have documented significant lung pathology. In this study, we analyzed both pulmonary and cardiac structure, histology, and gene expression at 48 h and 10 wks post fat injection to mimic FE.

RESULTS

Despite severe inflammatory evidence and structural changes to the lung and vasculature up to 10 wks after FE, we found no significant alterations to cardiovascular morphometry including lumen patency ratio, adventitia/media ratio, fibrosis content, and heart chamber/wall dimensions in stained histological sections. Additionally, genetic markers of cardiac pathological hypertrophy were not significantly elevated 48 h or 10 wks after fat treatment. Oil Red O staining showed increased fat droplet content within lung and aorta tissue, but not in the myocardium.

CONCLUSIONS

Our study suggests that, in contrast to the lungs, the heart is more resistant to the inflammatory and remodeling responses that result from FE, possibly due to the organ-specific differences in fat retention.

Advances in understanding and managing pediatric heart failure and transplant

PURPOSE OF REVIEW

This article highlights the most recent advances in a review of the current literature in the field of pediatric heart failure and transplantation.

RECENT FINDINGS

Diagnostically, the identification of new genetic factors has contributed to a deeper understanding of cardiomyopathy in children. Novel medications like sacubitril/valsartan and Sodium-Glucose cotransporter-2 (SGLT2) inhibitors, which are now standard in the adult population are being studied in pediatric population and offer new promise of pediatric heart failure treatment. Ventricular assist devices are more commonly used in cardiomyopathy patients and single ventricle patients as a bridge to transplant. Recent pediatric heart transplant society (PHTS) data demonstrated that waitlist survival improved significantly over the past decades (i) and new treatments such as daratumumab and eculizumab have been used in high-risk populations and demonstrate promising results. TEAMMATE trial is the first multicenter randomized clinical trial (RCT) in pediatric heart transplant (HT) to evaluate the safety and efficacy of everolimus (EVL) and low-dose tacrolimus (TAC) compared to standard-dose TAC and mycophenolate mofetil (MMF). It will provide valuable information about the safety and efficacy of EVL, TAC, and MMF (ii).Donor cell-free DNA has been used more in pediatric transplant recipients and has significantly decreased invasive EMB (iii).

SUMMARY

This past 5 years have witness dramatic progress in the field of pediatric heart failure and transplantation including more use of mechanical support in heart failure patients with various underlying etiology, especially use of mechanical support in single ventricle patients and the use of sacubitril/valsartan and SGLT2 inhibitors in the pediatric population. The problem of the highly sensitized transplant recipient remains, although novel therapeutics have been added to our toolbox of options to maintain healthy allograft function. Ongoing research aims to further enhance our understanding and management of pediatric heart failure, emphasizing the need for continued innovation in this complex field.

Mitochondrial abnormalities in septic cardiomyopathy

Septic cardiomyopathy is a common complication in patients with sepsis, and is one of the indicators of poor prognosis. Its pathogenesis is complex, involving calcium ion imbalance in cardiomyocytes, nitric oxide (NO) synthesis disorder, mitochondrial abnormalities and immune inflammatory reaction, especially mitochondrial abnormalities. In this paper, the mechanism of mitochondrial abnormalities causing septic cardiomyopathy was discussed from the aspects of mitochondrial structure change, mitochondrial energy metabolism disorder, redox imbalance, mitochondrial calcium overload, mitochondrial biosynthesis and autophagy abnormalities.

Protective Mechanisms of SGLTi in Ischemic Heart Disease

Ischemic heart disease (IHD) is a common clinical cardiovascular disease with high morbidity and mortality. Sodium glucose cotransporter protein inhibitor (SGLTi) is a novel hypoglycemic drug. To date, both clinical trials and animal experiments have shown that SGLTi play a protective role in IHD, including myocardial infarction (MI) and ischemia/reperfusion (I/R). The protective effects may be involved in mechanisms of energy metabolic conversion, anti-inflammation, anti-fibrosis, ionic homeostasis improvement, immune cell development, angiogenesis and functional regulation, gut microbiota regulation, and epicardial lipids. Thus, this review summarizes the above mechanisms and aims to provide theoretical evidence for therapeutic strategies for IHD.

A Feasibility Study of [18F]F-AraG Positron Emission Tomography (PET) for Cardiac Imaging-Myocardial Viability in Ischemia-Reperfusion Injury Model

PURPOSE

Myocardial infarction (MI) with subsequent inflammation is one of the most common heart conditions leading to progressive tissue damage. A reliable imaging marker to assess tissue viability after MI would help determine the risks and benefits of any intervention. In this study, we investigate whether a new mitochondria-targeted imaging agent, 18F-labeled 2'-deoxy-2'-18F-fluoro-9-β-d-arabinofuranosylguanine ([18F]F-AraG), a positron emission tomography (PET) agent developed for imaging activated T cells, is suitable for cardiac imaging and to test the myocardial viability after MI.

PROCEDURE

To test whether the myocardial [18F]-F-AraG signal is coming from cardiomyocytes or immune infiltrates, we compared cardiac signal in wild-type (WT) mice with that of T cell deficient Rag1 knockout (Rag1 KO) mice. We assessed the effect of dietary nucleotides on myocardial [18F]F-AraG uptake in normal heart by comparing [18F]F-AraG signals between mice fed with purified diet and those fed with purified diet supplemented with nucleotides. The myocardial viability was investigated in rodent model by imaging rat with [18F]F-AraG and 2-deoxy-2[18F]fluoro-D-glucose ([18F]FDG) before and after MI. All PET signals were quantified in terms of the percent injected dose per cc (%ID/cc). We also explored [18F]FDG signal variability and potential T cell infiltration into fibrotic area in the affected myocardium with H&E analysis.

RESULTS

The difference in %ID/cc for Rag1 KO and WT mice was not significant (p = ns) indicating that the [18F]F-AraG signal in the myocardium was primarily coming from cardiomyocytes. No difference in myocardial uptake was observed between [18F]F-AraG signals in mice fed with purified diet and with purified diet supplemented with nucleotides (p = ns). The [18F]FDG signals showed wider variability at different time points. Noticeable [18F]F-AraG signals were observed in the affected MI regions. There were T cells in the fibrotic area in the H&E analysis, but they did not constitute the predominant infiltrates.

CONCLUSIONS

Our preliminary preclinical data show that [18F]F-AraG accumulates in cardiomyocytes indicating that it may be suitable for cardiac imaging and to evaluate the myocardial viability after MI.

An intrinsic mechanism of metabolic tuning promotes cardiac resilience to stress

Defining the molecular mechanisms underlying cardiac resilience is crucial to find effective approaches to protect the heart. A physiologic level of ROS is produced in the heart by fatty acid oxidation, but stressful events can boost ROS and cause mitochondrial dysfunction and cardiac functional impairment. Melusin is a muscle specific chaperone required for myocardial compensatory remodeling during stress. Here we report that Melusin localizes in mitochondria where it binds the mitochondrial trifunctional protein, a key enzyme in fatty acid oxidation, and decreases it activity. Studying both mice and human induced pluripotent stem cell-derived cardiomyocytes, we found that Melusin reduces lipid oxidation in the myocardium and limits ROS generation in steady state and during pressure overload and doxorubicin treatment, preventing mitochondrial dysfunction. Accordingly, the treatment with the lipid oxidation inhibitor Trimetazidine concomitantly with stressful stimuli limits ROS accumulation and prevents long-term heart dysfunction. These findings disclose a physiologic mechanism of metabolic regulation in the heart and demonstrate that a timely restriction of lipid metabolism represents a potential therapeutic strategy to improve cardiac resilience to stress.

Association between appendicular skeletal muscle mass and myocardial glucose uptake measured by 18F-FDG PET

BACKGROUND

Low muscle mass is associated with high insulin resistance and an increased risk of cardiovascular disease. This study aims to determine whether low muscle mass affects the alterations in myocardial substrate metabolism that are associated with the development of cardiovascular disease.

METHOD

The study included 299 individuals (182 men and 117 women) who underwent examination at the Severance Health Check-up Center between January 2018 and February 2019. Myocardial glucose uptake was assessed using [18F]-fluorodeoxyglucose-positron emission tomography (18F-FDG PET/CT) scanning. Direct segmental bioimpedance analysis was used to measure appendicular skeletal muscle mass (ASM).

RESULTS

We analysed men and women separately owing to sex-related body composition differences. ASM/Ht2 was significantly positively correlated with myocardial glucose uptake measured by 18F-FDG PET/CT [ln (SUVheart/liver)] only in men (r = 0.154, P = 0.038 in men; r = -0.042, P = 0.652 in women, respectively). In men, myocardial glucose uptake was significantly associated with ASM/Ht2 even after adjusting for multiple confounders in a multivariable linear regression model (standardized β = 0.397, P = 0.004, in men; β = - 0.051, P = 0.698, in women). In women, age (β = -0.424 P = 0.029) was independent determinants of myocardial glucose uptake.

CONCLUSIONS

In men, ASM was strongly associated with myocardial glucose uptake as measured by 18F-FDG PET/CT. In women, age was significantly correlated with myocardial substrate utilization, but not with ASM.

New Insights into Mitochondria in Health and Diseases

Mitochondria are a unique type of semi-autonomous organelle within the cell that carry out essential functions crucial for the cell's survival and well-being. They are the location where eukaryotic cells carry out energy metabolism. Aside from producing the majority of ATP through oxidative phosphorylation, which provides essential energy for cellular functions, mitochondria also participate in other metabolic processes within the cell, such as the electron transport chain, citric acid cycle, and β-oxidation of fatty acids. Furthermore, mitochondria regulate the production and elimination of ROS, the synthesis of nucleotides and amino acids, the balance of calcium ions, and the process of cell death. Therefore, it is widely accepted that mitochondrial dysfunction is a factor that causes or contributes to the development and advancement of various diseases. These include common systemic diseases, such as aging, diabetes, Parkinson's disease, and cancer, as well as rare metabolic disorders, like Kearns-Sayre syndrome, Leigh disease, and mitochondrial myopathy. This overview outlines the various mechanisms by which mitochondria are involved in numerous illnesses and cellular physiological activities. Additionally, it provides new discoveries regarding the involvement of mitochondria in both disorders and the maintenance of good health.

Intermedin Alleviates Diabetic Cardiomyopathy by Up-Regulating CPT-1β through Activation of the Phosphatidyl Inositol 3 Kinase/Protein Kinase B Signaling Pathway

Diabetic cardiomyopathy (DCM), one of the most serious long-term consequences of diabetes, is closely associated with myocardial fatty acid metabolism. Carnitine palmitoyltransferase-1β (CPT-1β) is the rate-limiting enzyme responsible for β-oxidation of long-chain fatty acids. Intermedin (IMD) is a pivotal bioactive small molecule peptide, participating in the protection of various cardiovascular diseases. However, the role and underlying mechanisms of IMD in DCM are still unclear. In this study, we investigated whether IMD alleviates DCM via regulating CPT-1β. A rat DCM model was established by having rats to drink fructose water for 12 weeks. A mouse DCM model was induced by feeding mice a high-fat diet for 16 weeks. We showed that IMD and its receptor complexes levels were significantly down-regulated in the cardiac tissues of DCM rats and mice. Reduced expression of IMD was also observed in neonatal rat cardiomyocytes treated with palmitic acid (PA, 300 μM) in vitro. Exogenous and endogenous IMD mitigated cardiac hypertrophy, fibrosis, dysfunction, and lipid accumulation in DCM rats and IMD-transgenic DCM mice, whereas knockout of IMD worsened these pathological processes in IMD-knockout DCM mice. In vitro, IMD alleviated PA-induced cardiomyocyte hypertrophy and cardiac fibroblast activation. We found that CPT-1β enzyme activity, mRNA and protein levels, and acetyl-CoA content were increased in T2DM patients, rats and mice. IMD up-regulated the CPT-1β levels and acetyl-CoA content in T2DM rats and mice. Knockdown of CPT-1β blocked the effects of IMD on increasing acetyl-CoA content and on inhibiting cardiomyocyte hypertrophy and cardiac fibroblast activation. IMD receptor antagonist IMD17-47 and the phosphatidyl inositol 3 kinase (PI3K)/protein kinase B (Akt) inhibitor LY294002 reversed the effects of IMD on up-regulating CPT-1β and acetyl-CoA expression and on inhibiting cardiomyocyte hypertrophy and cardiac fibroblast activation. We revealed that IMD alleviates DCM by up-regulating CPT-1β via calcitonin receptor-like receptor/receptor activity-modifying protein (CRLR/RAMP) receptor complexes and PI3K/Akt signaling. IMD may serve as a potent therapeutic target for the treatment of DCM.

Hyperpolarized [1-13C]pyruvate cardiovascular magnetic resonance imaging identifies metabolic phenotypes in patients with heart failure

BACKGROUND

Hyperpolarized [1-13C]pyruvate cardiovascular magnetic resonance imaging (HP [1-13C]pyruvate CMR) visualizes key steps in myocardial metabolism. The present study aimed to examine patients with heart failure (HF) using HP [1-13C]pyruvate CMR.

METHODS

A cross-sectional study of patients with HF and healthy controls using HP [1-13C]pyruvate CMR. Metabolic imaging was obtained using a cardiac-gated spectral-spatial excitation with spiral read-out acquisition. The metabolite signal was analyzed for lactate, bicarbonate, and the alanine signal. Metabolite signal was normalized to the total carbon signal (TC). At the 1-year follow-up, echocardiography was performed in all patients and HP [1-13C]pyruvate MRI in two patients.

RESULTS

We included six patients with ischemic heart disease (IHD), six with dilated cardiomyopathy, and six healthy controls. In patients, left ventricular ejection fraction (LVEF) correlated with lactate/bicarbonate (r = -0.6, p = 0.03) and lactate/TC (r = -0.7, p = 0.01). In patients with LVEF <30%, lactate/TC was increased (p = 0.01) and bicarbonate/TC reduced (p = 0.03). Circumferential strain correlated with metabolite ratios: lactate/bicarbonate, r = 0.87 (p = 0.0002); lactate/TC, r = 0.85 (p = 0.0005); bicarbonate/TC, r = -0.82 (p = 0.001). In patients with IHD, a strong correlation was found between baseline metabolite ratios and the change in LVEF at follow-up: lactate/bicarbonate (p = 0.001), lactate/TC (p = 0.011), and bicarbonate/TC (p = 0.012).

CONCLUSIONS

This study highlighted the ability of HP [1-13C]pyruvate CMR to detect changes in metabolism in HF. HP [1-13C]pyruvate CMR has the potential for metabolic phenotyping of patients with HF and for predicting treatment response.

TRIAL REGISTRATION

EUDRACT, 2018-003533-15. Registered December 4, 2018, https://www.clinicaltrialsregister.eu/ctr-search/search?query=2018-003533-15.

Alpha-ketoglutarate is required for chronic hypoxia-induced cardiac remodeling

Chronic hypoxia (CH) is commonly associated with various cardiovascular diseases, with cardiac hypertrophy being the most frequently observed alteration. Metabolic remodeling is another consequence seen in the hypoxic heart. However, the mechanistic linkage between metabolic remodeling and cardiac hypertrophy in the hypoxic heart remains unclear. In this study, wild-type C57BL/6J mice were subjected to CH for 4 wk. Echocardiography and morphological analysis were used to assess the cardiac effects. We found that 4 wk of CH led to significant cardiac hypertrophy in the mice, whereas cardiac function remained unchanged compared with normoxic mice. In addition, CH induced an elevation in cardiac alpha-ketoglutarate (α-KG) content. Promoting α-KG degradation in the CH hearts prevented CH-induced cardiac hypertrophy but led to noticeable cardiac dysfunction. Mechanistically, α-KG promoted the transcription of hypertrophy-related genes by regulating histone methylation. Silencing lysine-specific demethylase 5 (KDM5), a histone demethylation enzyme, blunted α-KG-induced transcription of hypertrophy-related genes. These data suggest that α-KG is required for CH-induced cardiac remodeling, thus establishing a connection between metabolic changes and cardiac remodeling in hypoxic hearts.NEW & NOTEWORTHY We reported that alpha-ketoglutarate (α-KG) is indispensable for chronic hypoxia (CH)-induced cardiac remodeling, which builds the bridge between metabolic intermediates and cardiac remodeling.

Evidence for enduring cardiac and multiorgan toxicity after repeated exposure to the synthetic cannabinoid JWH-018 in male rats

The use of synthetic cannabinoid receptor agonists (SCRAs) represents a public health concern. Besides abuse liability and cognitive impairments, SCRAs consumption is associated with serious medical consequences in humans, including cardiotoxicity. The precise mechanisms underlying cardiac or other toxicities induced by SCRAs are not well understood. Here, we used in silico, in vivo, and ex vivo approaches to investigate the toxicological consequences induced by exposure to the SCRA JWH-018. Along with in silico predictive toxicological screening of 36 SCRAs by MC4PC software, adult male Sprague-Dawley rats were repeatedly exposed to JWH-018 (0.25 mg/kg ip) for 14 consecutive days, with body temperature and cardiovascular parameters measured over the course of treatment. At 1 and 7 days after JWH-018 discontinuation, multiorgan tissue pathologies and heart mitochondria bioenergetics were assessed. The in silico findings predicted risk of cardiac adverse effects specifically for JWH-018 and other aminoalkylindole SCRAs (i.e., electrocardiogram abnormality and QT prolongation). The results from rats revealed that repeated, but not single, JWH-018 exposure induced hypothermia and cardiovascular stimulation (e.g., increased blood pressure and heart rate) which persisted throughout treatment. Post-mortem findings demonstrated cardiac lesions (i.e., vacuolization, waving, edema) 1 day after JWH-018 discontinuation, which may contribute to lung, kidney, and liver tissue degeneration observed 7 days later. Importantly, repeated JWH-018 exposure induced mitochondrial dysfunction in cardiomyocytes, i.e., defective lipid OXPHOS, which may represent one mechanism of JWH-018-induced toxicity. Our results demonstrate that repeated administration of even a relatively low dose of JWH-018 is sufficient to affect cardiovascular function and induce enduring toxicological consequences, pointing to risks associated with SCRA consumption.

Metabolic Choreography of Energy Substrates During DCD Heart Perfusion

Background

The number of patients waiting for heart transplant far exceeds the number of hearts available. Donation after circulatory death (DCD) combined with machine perfusion can increase the number of transplantable hearts by as much as 48%. Emerging studies also suggest machine perfusion could enable allograft "reconditioning" to optimize outcomes. However, a detailed understanding of the energetic substrates and metabolic changes during perfusion is lacking.

Methods

Metabolites were analyzed using 1-dimensional 1H and 2-dimensional 13C-1H heteronuclear spectrum quantum correlation nuclear magnetic resonance spectroscopy on serial perfusate samples (N = 98) from 32 DCD hearts that were successfully transplanted. Wilcoxon signed-rank and Kruskal-Wallis tests were used to test for significant differences in metabolite resonances during perfusion and network analysis was used to uncover altered metabolic pathways.

Results

Metabolite differences were observed comparing baseline perfusate to samples from hearts at time points 1-2, 3-4, and 5-6 h of perfusion and all pairwise combinations. Among the most significant changes observed were a steady decrease in fatty acids and succinate and an increase in amino acids, especially alanine, glutamine, and glycine. This core set of metabolites was also altered in a DCD porcine model perfused with a nonblood-based perfusate.

Conclusions

Temporal metabolic changes were identified during ex vivo perfusion of DCD hearts. Fatty acids, which are normally the predominant myocardial energy source, are rapidly depleted, while amino acids such as alanine, glutamine, and glycine increase. We also noted depletion of ketone, β-hydroxybutyric acid, which is known to have cardioprotective properties. Collectively, these results suggest a shift in energy substrates and provide a basis to design optimal preservation techniques during perfusion.

Assessing the importance and safety of hypoxia conditioning for patients with occupational pulmonary diseases: A recent clinical perspective

Occupational pulmonary diseases (OPDs) pose a significant global health challenge, contributing to high mortality rates. This review delves into the pathophysiology of hypoxia and the safety of intermittent hypoxic conditioning (IHC) in OPD patients. By examining sources such as PubMed, Relemed, NLM, Scopus, and Google Scholar, the review evaluates the efficacy of IHC in clinical outcomes for OPD patients. It highlights the complexities of cardiovascular and respiratory regulation dysfunctions in OPDs, focusing on respiratory control abnormalities and the impact of intermittent hypoxic exposures. Key areas include the physiological effects of hypoxia, the role of hypoxia-inducible factor-1 alpha (HIF-1α) in occupational lung diseases, and the links between brain ischemia, stroke, and OPDs. The review also explores the interaction between intermittent hypoxic exposures, mitochondrial energetics, and lung physiology. The potential of IHE to improve clinical manifestations and underlying pathophysiology in OPD patients is thoroughly examined. This comprehensive analysis aims to benefit molecular pathologists, pulmonologists, clinicians, and physicians by enhancing understanding of IHE's clinical benefits, from research to patient care, and improving clinical outcomes for OPD patients.

Etomoxir-carnitine, a novel pharmaco-metabolite of etomoxir, inhibits phospholipases A2 and mitochondrial respiration

Mitochondrial fatty acid oxidation serves as an essential process for cellular survival, differentiation, proliferation, and energy metabolism. Numerous studies have utilized etomoxir (ETO) for the irreversible inhibition of carnitine palmitoylcarnitine transferase 1 (CPT1), which catalyzes the rate-limiting step for mitochondrial long-chain fatty acid β-oxidation to examine the bioenergetic roles of mitochondrial fatty acid metabolism in many tissues in multiple diverse disease states. Herein, we demonstrate that intact mitochondria robustly metabolize ETO to etomoxir-carnitine (ETO-carnitine) prior to nearly complete ETO-mediated inhibition of CPT1. The novel pharmaco-metabolite, ETO-carnitine, was conclusively identified by accurate mass, fragmentation patterns, and isotopic fine structure. On the basis of these data, ETO-carnitine was successfully differentiated from isobaric structures (e.g., 3-hydroxy-C18:0 carnitine and 3-hydroxy-C18:1 carnitine). Mechanistically, generation of ETO-carnitine from mitochondria required exogenous Mg2+, ATP or ADP, CoASH, and L-carnitine, indicating that thioesterification by long-chain acyl-CoA synthetase to form ETO-CoA precedes its conversion to ETO-carnitine by CPT1. CPT1-dependent generation of ETO-carnitine was substantiated by an orthogonal approach using ST1326 (a CPT1 inhibitor), which effectively inhibits mitochondrial ETO-carnitine production. Surprisingly, purified ETO-carnitine potently inhibited calcium-independent PLA2γ and PLA2β as well as mitochondrial respiration independent of CPT1. Robust production and release of ETO-carnitine from HepG2 cells incubated in the presence of ETO was also demonstrated. Collectively, this study identifies the chemical mechanism for the biosynthesis of a novel pharmaco-metabolite of ETO, ETO-carnitine, that is generated by CPT1 in mitochondria and likely impacts multiple downstream (non-CPT1 related) enzymes and processes in multiple subcellular compartments.

Role of AMPK in Atrial Metabolic Homeostasis and Substrate Preference

Atrial fibrillation is the most common clinical arrhythmia and may be due in part to metabolic stress. Atrial specific deletion of the master metabolic sensor, AMP-activated protein kinase (AMPK), induces atrial remodeling culminating in atrial fibrillation in mice, implicating AMPK signaling in the maintenance of atrial electrical and structural homeostasis. However, atrial substrate preference for mitochondrial oxidation and the role of AMPK in regulating atrial metabolism are unknown. Here, using LC-MS/MS methodology combined with infusions of [ 13 C 6 ]glucose and [ 13 C 4 ]β-hydroxybutyrate in conscious mice, we demonstrate that conditional deletion of atrial AMPK catalytic subunits shifts mitochondrial atrial metabolism away from fatty acid oxidation and towards pyruvate oxidation. LC-MS/MS-based quantification of acyl-CoAs demonstrated decreased atrial tissue content of long-chain fatty acyl-CoAs. Proteomic analysis revealed a broad downregulation of proteins responsible for fatty acid uptake (LPL, CD36, FABP3), acylation and oxidation. Atrial AMPK deletion reduced expression of atrial PGC1-α and downstream PGC1-α/PPARα/RXR regulated gene transcripts. In contrast, atrial [ 14 C]2-deoxyglucose uptake and GLUT1 expression increased with fasting in mice with AMPK deletion, while the expression of glycolytic enzymes exhibited heterogenous changes. Thus, these results highlight the crucial homeostatic role of AMPK in the atrium, with loss of atrial AMPK leading to downregulation of the PGC1-α/PPARα pathway and broad metabolic reprogramming with a loss of fatty acid oxidation, which may contribute to atrial remodeling and arrhythmia.

Exploring the impact of metabolites function on heart failure and coronary heart disease: insights from a Mendelian randomization (MR) study

BACKGROUND

Heart failure (HF) and coronary heart disease (CHD) are major causes of morbidity and mortality worldwide. While traditional risk factors such as hypertension, diabetes, and smoking have been extensively studied, the role of metabolite functions in the development of these cardiovascular conditions has been less explored. This study employed a Mendelian randomization (MR) approach to investigate the impact of metabolite functions on HF and CHD.

METHODS

To assess the causal impacts of specific metabolite risk factors on HF and CHD, this study utilized genetic variants associated with these factors as instrumental variables. Comprehensive genetic and phenotypic data from diverse cohorts, including genome-wide association studies (GWAS) and cardiovascular disease registries, were incorporated into the research.

RESULTS

Our results encompass 61 metabolic cell phenotypes, with ten providing strong evidence of the influence of metabolite functions on the occurrence of HF and CHD. We found that elevated levels of erucate (22:1n9), lower levels of α-tocopherol, an imbalanced citrulline-to-ornithine ratio, elevated γ-glutamyl glycine levels, and elevated 7-methylguanine levels independently increased the risk of these cardiovascular conditions. These findings were consistent across different populations and robust to sensitivity analyses.

CONCLUSION

This MR study provides valuable insights into the influence of metabolite functions on HF and CHD. However, further investigation is needed to fully understand the precise mechanisms by which these metabolite factors contribute to the onset of these conditions. Such research could pave the way for the development of targeted therapeutic strategies.

Voluntary Wheel Running Reduces Cardiometabolic Risks in Female Offspring Exposed to Lifelong High-Fat, High-Sucrose Diet

PURPOSE

Maternal and postnatal overnutrition has been linked to an increased risk of cardiometabolic diseases in offspring. This study investigated the impact of adult-onset voluntary wheel running to counteract cardiometabolic risks in female offspring exposed to a life-long high-fat, high-sucrose (HFHS) diet.

METHODS

Dams were fed either an HFHS or a low-fat, low-sucrose (LFLS) diet starting from 8 wk before pregnancy and continuing throughout gestation and lactation. Offspring followed their mothers' diets. At 15 wk of age, they were divided into sedentary (Sed) or voluntary wheel running (Ex) groups, resulting in four groups: LFLS/Sed ( n = 10), LFLS/Ex ( n = 5), HFHS/Sed ( n = 6), HFHS/Ex ( n = 5). Cardiac function was assessed at 25 wk, with tissue collection at 26 wk for mitochondrial respiratory function and protein analysis. Data were analyzed using two-way ANOVA.

RESULTS

Although maternal HFHS diet did not affect the offspring's body weight at weaning, continuous HFHS feeding postweaning resulted in increased body weight and adiposity, irrespective of the exercise regimen. HFHS/Sed offspring showed increased left ventricular wall thickness and elevated expression of enzymes involved in fatty acid transport (CD36, FABP3), lipogenesis (DGAT), glucose transport (GLUT4), oxidative stress (protein carbonyls, nitrotyrosine), and early senescence markers (p16, p21). Their cardiac mitochondria displayed lower oxidative phosphorylation (OXPHOS) efficiency and reduced expression of OXPHOS complexes and fatty acid metabolism enzymes (ACSL5, CPT1B). However, HFHS/Ex offspring mitigated these effects, aligning more with LFLS/Sed offspring.

CONCLUSIONS

Adult-onset voluntary wheel running effectively counteracts the detrimental cardiac effects of a lifelong HFHS diet, improving mitochondrial efficiency, reducing oxidative stress, and preventing early senescence. This underscores the significant role of physical activity in mitigating diet-induced cardiometabolic risks.

Programmed spontaneously beating cardiomyocytes in regenerative cardiology

Stem cells have gained attention as a promising therapeutic approach for damaged myocardium, and there have been efforts to develop a protocol for regenerating cardiomyocytes (CMs). Certain cells have showed a greater aptitude for yielding beating CMs, such as induced pluripotent stem cells, embryonic stem cells, adipose-derived stromal vascular fraction cells and extended pluripotent stem cells. The approach for generating CMs from stem cells differs across studies, although there is evidence that Wnt signaling, chemical additives, electrical stimulation, co-culture, biomaterials and transcription factors triggers CM differentiation. Upregulation of Gata4, Mef2c and Tbx5 transcription factors has been correlated with successfully induced CMs, although Mef2c may potentially play a more prominent role in the generation of the beating phenotype, specifically. Regenerative research provides a possible candidate for cardiac repair; however, it is important to identify factors that influence their differentiation. Altogether, the spontaneously beating CMs would be monumental for regenerative research for cardiac repair.

Insulin-Heart Axis: Bridging Physiology to Insulin Resistance

Insulin signaling is vital for regulating cellular metabolism, growth, and survival pathways, particularly in tissues such as adipose, skeletal muscle, liver, and brain. Its role in the heart, however, is less well-explored. The heart, requiring significant ATP to fuel its contractile machinery, relies on insulin signaling to manage myocardial substrate supply and directly affect cardiac muscle metabolism. This review investigates the insulin-heart axis, focusing on insulin's multifaceted influence on cardiac function, from metabolic regulation to the development of physiological cardiac hypertrophy. A central theme of this review is the pathophysiology of insulin resistance and its profound implications for cardiac health. We discuss the intricate molecular mechanisms by which insulin signaling modulates glucose and fatty acid metabolism in cardiomyocytes, emphasizing its pivotal role in maintaining cardiac energy homeostasis. Insulin resistance disrupts these processes, leading to significant cardiac metabolic disturbances, autonomic dysfunction, subcellular signaling abnormalities, and activation of the renin-angiotensin-aldosterone system. These factors collectively contribute to the progression of diabetic cardiomyopathy and other cardiovascular diseases. Insulin resistance is linked to hypertrophy, fibrosis, diastolic dysfunction, and systolic heart failure, exacerbating the risk of coronary artery disease and heart failure. Understanding the insulin-heart axis is crucial for developing therapeutic strategies to mitigate the cardiovascular complications associated with insulin resistance and diabetes.

Enhancing mitochondrial pyruvate metabolism ameliorates ischemic reperfusion injury in the heart

The clinical therapy for treating acute myocardial infarction is primary percutaneous coronary intervention (PPCI). PPCI is effective at reperfusing the heart; however, the rapid reintroduction of blood can cause ischemia-reperfusion (I/R). Reperfusion injury is responsible for up to half of the total myocardial damage, but there are no pharmacological interventions to reduce I/R. We previously demonstrated that inhibiting monocarboxylate transporter 4 (MCT4) and redirecting pyruvate toward oxidation can blunt hypertrophy. We hypothesized that this pathway might be important during I/R. Here, we establish that the pyruvate-lactate axis plays a role in determining myocardial salvage following injury. After I/R, the mitochondrial pyruvate carrier (MPC), required for pyruvate oxidation, is upregulated in the surviving myocardium. In cardiomyocytes lacking the MPC, there was increased cell death and less salvage after I/R, which was associated with an upregulation of MCT4. To determine the importance of pyruvate oxidation, we inhibited MCT4 with a small-molecule drug (VB124) at reperfusion. This strategy normalized reactive oxygen species (ROS), mitochondrial membrane potential (ΔΨ), and Ca2+, increased pyruvate entry to the TCA cycle, increased oxygen consumption, and improved myocardial salvage and functional outcomes following I/R. Our data suggest normalizing pyruvate-lactate metabolism by inhibiting MCT4 is a promising therapy to mitigate I/R injury.

PPAR-α regulates metabolic remodelling and participates in myocardial fibrosis in patients with atrial fibrillation of rheumatic heart disease

Introduction

This study will explore the correlation of peroxisome proliferator activated receptor-α (PPAR-α) regulation of metabolic remodelling in the myocardial fibrosis of atrial fibrillation (AF) in rheumatic heart disease.

Material and methods

The left atrial appendage tissues were evaluated by Masson staining for fibrosis degree, and Western Blot was used to detect the expression of proteins related to glucose metabolism disorder, lipid metabolism abnormality, and mitochondrial dysfunction. The myocardial fibroblasts were established by stimulation with ANG II, and the PPAR-α agonist GW7647 was administered. The changes of phenotype transformation of myocardial fibroblasts were detected by cellular immunofluorescence, the secretion level of supernatant collagen was detected by ELISA. Finally, the correlation between PPAR-α protein expression and myocardial fibrosis was analysed and a conclusion was drawn.

Results

Masson staining showed that the degree of myocardial fibrosis in patients with AF was significantly increased; WB analysis showed that there were statistically significant differences in protein expression related to glucose metabolism disorder, lipid metabolism abnormality, and mitochondrial dysfunction. There was a correlation between PPAR-α protein expression and myocardial fibrosis (r = -0.5322, p < 0.0001). After stimulation with PPAR-α agonist GW7647, the phenotypic differentiation of myocardial fibro-blasts into myofibroblasts was inhibited. The protein expression related to mitochondrial dysfunction was statistically different.

Conclusions

This study found that there is a negative correlation between the expression of PPAR-α protein and myocardial fibrosis in rheumatic heart disease AF, which plays a protective role. PPAR-α may participate in the pathogenesis of myocardial fibrosis in rheumatic heart disease AF by regulating glucose metabolism, lipid metabolism, and mitochondrial function.

Independent effects of the glucose-to-glycated hemoglobin ratio on mortality in critically ill patients with atrial fibrillation

BACKGROUND

The glucose-to-glycated hemoglobin ratio (GAR) represents stress hyperglycemia, which has been closely associated with adverse outcomes in cardio-cerebrovascular diseases. No studies have examined the association between stress hyperglycemia and atrial fibrillation (AF) in critically ill patients. This study aims to explore the relationship between GAR and the prognosis of critically ill patients with AF.

METHODS

A retrospective cohort of patients was selected from the Medical Information Mart for Intensive Care IV (MIMIC-IV) database. The GAR was calculated based on fasting blood glucose and glycated hemoglobin levels measured after admission. The primary outcome was the 30-day mortality rate, with secondary outcomes being the 90-day and 365-day mortality rates. The GAR was divided into tertiles, and Kaplan-Meier analysis was employed to compare differences in mortality rates between groups. The Cox proportional hazards model and restricted cubic splines (RCS) were utilized to evaluate the relationship between the GAR and mortality. Subsequently, a segmented regression model was constructed to analyze threshold effects in cases where nonlinear relationships were determined.

RESULTS

In this cohort, the second tertile of the GAR exhibited lower mortality rates at 30 days (10.56% vs 6.33% vs 14.51%), 90 days (17.11% vs 10.09% vs 17.88%), and 365 days (25.30% vs 16.15% vs 22.72%). In the third tertile, the risk of mortality at 30 days increased by 165% (HR = 2.65, 95% CI 1.99-3.54, p < 0.001), at 90 days increased by 113% (HR = 2.13, 95% CI 1.68-2.70, p < 0.001), and at 365 days increased by 70% (HR = 1.70, 95% CI 1.68-2.70, p < 0.001). The association between the GAR and patient mortality demonstrated a "J-shaped" non-linear correlation. Once the GAR exceeded 15.915, each incremental unit increase in the ratio was associated with a 27.2% increase in the risk of 30-day mortality in critically ill atrial fibrillation patients (HR = 1.262, 95% CI 1.214-1.333, p < 0.001).

CONCLUSION

The GAR is associated with both short-term and long-term mortality in critically ill patients with AF in a J-shaped relationship. Both low and excessively high GAR values indicate poor prognosis.

Bromuconazole exposure induces cardiac dysfunction by upregulating the expression LEF1

With the wide application of bromuconazole (BRO), a kind of triazole fungicide, the environmental problems caused by BRO have been paid more and more attention. In this study, adult male zebrafish were exposed to environmental related concentration and the maximum non-lethal concentration for zebrafish larvae (0,50 ng/L and 7.5 mg/L) for 7 days, respectively. Zebrafish exposed to BRO exhibited a significant reduction in body length and an increase in fatness index, indicating adverse physiological changes. Notably, the exposed zebrafish showed enlarged heart ventricular volumes and thinner heart walls. Transcriptome analysis of heart samples showed that BRO exposure mainly affected pathways related to cardiac energy metabolism. In addition, the amount of ATP in the heart tissue was correspondingly reduced, and the expression levels of genes related to controlling ion balance and myosin synthesis in the heart were also altered. The study extended its findings to the rat cardiomyocytes (H9C2), where similar cardiotoxic effects including changes in transcription of genes related to energy metabolism and heart function were also observed, suggesting a potential universal mechanism of BRO-induced cardiotoxicity. In a doxorubicin (DOX) induced larval zebrafish heart failure model, the expression of lymphoid enhancer-binding factor 1(LEF1), a key gene in the Wnt/β-catenin signaling pathway, was significantly increased in larval zebrafish and adult fish heart tissues and cardiomyocytes, suggesting that LEF1 might play an important role in BRO-induced cardiotoxicity. Taken together, BRO exposure could interfere with cardiac function and metabolic capacity by abnormal activation the expression of LEF1. The study emphasized the urgent need for monitoring and regulating BRO due to its harmful effects on the hearts of aquatic organisms.

Cardiomyopathy in Duchenne Muscular Dystrophy and the Potential for Mitochondrial Therapeutics to Improve Treatment Response

Duchenne muscular dystrophy (DMD) is a progressive neuromuscular disease caused by mutations to the dystrophin gene, resulting in deficiency of dystrophin protein, loss of myofiber integrity in skeletal and cardiac muscle, and eventual cell death and replacement with fibrotic tissue. Pathologic cardiac manifestations occur in nearly every DMD patient, with the development of cardiomyopathy-the leading cause of death-inevitable by adulthood. As early cardiac abnormalities are difficult to detect, timely diagnosis and appropriate treatment modalities remain a challenge. There is no cure for DMD; treatment is aimed at delaying disease progression and alleviating symptoms. A comprehensive understanding of the pathophysiological mechanisms is crucial to the development of targeted treatments. While established hypotheses of underlying mechanisms include sarcolemmal weakening, upregulation of pro-inflammatory cytokines, and perturbed ion homeostasis, mitochondrial dysfunction is thought to be a potential key contributor. Several experimental compounds targeting the skeletal muscle pathology of DMD are in development, but the effects of such agents on cardiac function remain unclear. The synergistic integration of small molecule- and gene-target-based drugs with metabolic-, immune-, or ion balance-enhancing compounds into a combinatorial therapy offers potential for treating dystrophin deficiency-induced cardiomyopathy, making it crucial to understand the underlying mechanisms driving the disorder.

Exercise Hemodynamics and Mitochondrial Oxidative Capacity in Disease Stages of Wild-Type Transthyretin Amyloid Cardiomyopathy

BACKGROUND

Wild-type transthyretin amyloid (ATTRwt) cardiomyopathy is increasingly recognized in the development of heart failure. The link between cardiac performance, hemodynamics, and mitochondrial function in disease stages of ATTRwt has not previously been studied but may provide new insights into the pathophysiology and clinical performance of the patients.

METHODS AND RESULTS

The study investigated 47 patients diagnosed with ATTRwt at Aarhus University Hospital, Denmark. Patients were stratified according to the disease stages of the National Amyloidosis Centre (NAC) as NAC I with low levels of NT-proBNP (N-terminal pro-B-type natriuretic peptide) (NAC I-L, n=14), NAC I with high levels NT-proBNP (NAC I-H, n=20), and NAC II-III (n=13). Exercise testing with simultaneous right heart catheterization was performed in all patients. Endomyocardial biopsies were collected from the patients and the mitochondrial oxidative phosphorylation capacity was assessed. All NAC disease groups, even in the NAC I-L group, a significant abnormal increase in biventricular filling pressures were noted during exercise while the filling pressures was normal or near normal at rest. The inotropic response to exercise was reduced with diminished increase in cardiac output which was significantly more pronounced in the NAC I-H (Diff. -2.4, 95% CI (-4.2: -0.7), P=0.00) and the NAC II-III group (Diff: -3.1 L/min, 95% CI (-5.2: -1.1), P=0.00) compared with the NAC I-L group. The pulmonary artery wedge pressure to cardiac output ratio at peak exercise was significantly different between NAC I-L and NAC II-III (Diff: 1.6 mm Hg*min/L, 95% CI (0.01:3.3, P=0.04)). Patients with ATTRwt had a reduced oxidative phosphorylation capacity which correlated to left ventricular mass but not to cardiac output capacity.

CONCLUSIONS

An abnormal restrictive left ventricle and right ventricle response to exercise was demonstrated, even present in patients with early-stage ATTRwt. In more advanced disease stages a progressive impairment of the pressure-flow relationship was noted. The myocyte energetics is deranged but not associated to the contractile reserve or restrictive filling characteristics in ATTRwt.

Human cardiac metabolism

The heart is the most metabolically active organ in the human body, and cardiac metabolism has been studied for decades. However, the bulk of studies have focused on animal models. The objective of this review is to summarize specifically what is known about cardiac metabolism in humans. Techniques available to study human cardiac metabolism are first discussed, followed by a review of human cardiac metabolism in health and in heart failure. Mechanistic insights, where available, are reviewed, and the evidence for the contribution of metabolic insufficiency to heart failure, as well as past and current attempts at metabolism-based therapies, is also discussed.

Cadmium contributes to cardiac metabolic disruption by activating endothelial HIF1A-GLUT1 axis

Cadmium (Cd) is an environmental risk factor of cardiovascular diseases. Researchers have found that Cd exposure causes energy metabolic disorders in the heart decades ago. However, the underlying molecular mechanisms are still elusive. In this study, male C57BL/6 J mice were exposed to cadmium chloride (CdCl2) through drinking water for 4 weeks. We found that exposure to CdCl2 increased glucose uptake and utilization, and disrupted normal metabolisms in the heart. In vitro studies showed that CdCl2 specifically increased endothelial glucose uptake without affecting cardiomyocytic glucose uptake and endothelial fatty acid uptake. The glucose transporter 1 (GLUT1) as well as its transcription factor HIF1A was significantly increased after CdCl2 treatment in endothelial cells. Further investigations found that CdCl2 treatment upregulated HIF1A expression by inhibiting its degradation through ubiquitin-proteasome pathway, thereby promoted its transcriptional activation of SLC2A1. Administration of HIF1A small molecule inhibitor echinomycin and A-485 reversed CdCl2-mediated increase of glucose uptake in endothelial cells. In accordance with this, intravenous injection of echinomycin effectively ameliorated CdCl2-mediated metabolic disruptions in the heart. Our study uncovered the molecular mechanisms of Cd in contributing cardiac metabolic disruption by inhibiting HIF1A degradation and increasing GLUT1 transcriptional expression. Inhibition of HIF1A could be a potential strategy to ameliorate Cd-mediated cardiac metabolic disorders and Cd-related cardiovascular diseases.

Mitochondria and NLRP3 inflammasome in cardiac hypertrophy

Cardiac hypertrophy is the main adaptive response of the heart to chronic loads; however, prolonged or excessive hypertrophy promotes myocardial interstitial fibrosis, systolic dysfunction, and cardiomyocyte death, especially aseptic inflammation mediated by NLRP3 inflammasome, which can aggravate ventricular remodeling and myocardial damage, which is an important mechanism for the progression of heart failure. Various cardiac overloads can cause mitochondrial damage. In recent years, the mitochondria have been demonstrated to be involved in the inflammatory response during the development of cardiac hypertrophy in vitro and in vivo. As the NLRP3 inflammasome and mitochondria are regulators of inflammation and cardiac hypertrophy, we explored the potential functions of the NLRP3 inflammasome and mitochondrial dysfunction in cardiac hypertrophy. In particular, we proposed that the induction of mitochondrial dysfunction in cardiomyocytes may promote NLRP3-dependent inflammation during myocardial hypertrophy. Further in-depth studies could prompt valuable discoveries regarding the underlying molecular mechanisms of cardiac hypertrophy, reveal novel anti-inflammatory therapies for cardiac hypertrophy, and provide more desirable therapeutic outcomes for patients with cardiac hypertrophy.

Pyruvate Kinase M2: A Potential Regulator of Cardiac Injury Through Glycolytic and Non-glycolytic Pathways

ABSTRACT

Adult animals are unable to regenerate heart cells due to postnatal cardiomyocyte cycle arrest, leading to higher mortality rates in cardiomyopathy. However, reprogramming of energy metabolism in cardiomyocytes provides a new perspective on the contribution of glycolysis to repair, regeneration, and fibrosis after cardiac injury. Pyruvate kinase (PK) is a key enzyme in the glycolysis process. This review focuses on the glycolysis function of PKM2, although PKM1 and PKM2 both play significant roles in the process after cardiac injury. PKM2 exists in both low-activity dimer and high-activity tetramer forms. PKM2 dimers promote aerobic glycolysis but have low catalytic activity, leading to the accumulation of glycolytic intermediates. These intermediates enter the pentose phosphate pathway to promote cardiomyocyte proliferation and heart regeneration. Additionally, they activate adenosine triphosphate (ATP)-sensitive K + (K ATP ) channels, protecting the heart against ischemic damage. PKM2 tetramers function similar to PKM1 in glycolysis, promoting pyruvate oxidation and subsequently ATP generation to protect the heart from ischemic damage. They also activate KDM5 through the accumulation of αKG, thereby promoting cardiomyocyte proliferation and cardiac regeneration. Apart from glycolysis, PKM2 interacts with transcription factors like Jmjd4, RAC1, β-catenin, and hypoxia-inducible factor (HIF)-1α, playing various roles in homeostasis maintenance, remodeling, survival regulation, and neovascularization promotion. However, PKM2 has also been implicated in promoting cardiac fibrosis through mechanisms like sirtuin (SIRT) 3 deletion, TG2 expression enhancement, and activation of transforming growth factor-β1 (TGF-β1)/Smad2/3 and Jak2/Stat3 signals. Overall, PKM2 shows promising potential as a therapeutic target for promoting cardiomyocyte proliferation and cardiac regeneration and addressing cardiac fibrosis after injury.

An update of the molecular mechanisms underlying anthracycline induced cardiotoxicity

Anthracycline drugs mainly include doxorubicin, epirubicin, pirarubicin, and aclamycin, which are widely used to treat a variety of malignant tumors, such as breast cancer, gastrointestinal tumors, lymphoma, etc. With the accumulation of anthracycline drugs in the body, they can induce serious heart damage, limiting their clinical application. The mechanism by which anthracycline drugs cause cardiotoxicity is not yet clear. This review provides an overview of the different types of cardiac damage induced by anthracycline-class drugs and delves into the molecular mechanisms behind these injuries. Cardiac damage primarily involves alterations in myocardial cell function and pathological cell death, encompassing mitochondrial dysfunction, topoisomerase inhibition, disruptions in iron ion metabolism, myofibril degradation, and oxidative stress. Mechanisms of uptake and transport in anthracycline-induced cardiotoxicity are emphasized, as well as the role and breakthroughs of iPSC in cardiotoxicity studies. Selected novel cardioprotective therapies and mechanisms are updated. Mechanisms and protective strategies associated with anthracycline cardiotoxicity in animal experiments are examined, and the definition of drug damage in humans and animal models is discussed. Understanding these molecular mechanisms is of paramount importance in mitigating anthracycline-induced cardiac toxicity and guiding the development of safer approaches in cancer treatment.

The abnormalities of free fatty acid metabolism in patients with hypertrophic cardiomyopathy, a single-center retrospective observational study

BACKGROUND

Previous studies have shown the importance of energy deficiency and malfunctioning mitochondria in the pathophysiology of hypertrophic cardiomyopathy (HCM). There has been a little research into the relationship between plasma free fatty acids (FFA), one of the heart's main energy sources, and HCM. We evaluated its clinical importance in HCM to see if there was a link between plasma FFA metabolism and HCM.

METHODS

In a single-center retrospective observational study, we investigated 420 HCM patients diagnosed at Beijing Anzhen Hospital between January 1, 2018, and December 31, 2022. Meanwhile, 1372 individuals without HCM (non-HCM) were recruited. 391 non-HCM patients were chosen as controls via a propensity score matching (PSM) study with a 1:1 ratio.

RESULTS

FFA in HCM patients showed statistically significant correlations with creatinine (r = 0.115, p = 0.023), estimated GFR (r=-0.130, p = 0.010), BNP (r = 0.152, p = 0.007), LVEF (r=-0.227, p < 0.001), LVFS (r=-0.160, p = 0.002), and LAD (r = 0.112, p = 0.028). Higher FFA levels were found in HCM patients who had atrial fibrillation and NYHY functional classes III or IV (p = 0.015 and p = 0.022, respectively). In HCM patients, multiple linear regression analysis revealed that BNP and LVEF had independent relationships with increasing FFA (Standardized = 0.139, p = 0.013 and =-0.196, p < 0.001, respectively).

CONCLUSIONS

Among HCM patients, the plasma FFA concentration was lower, and those with AF and NYHY functional class III or IV had higher FFA levels, and LVEF and BNP were independently associated with increasing FFA. The findings of the study should help inspire future efforts to better understand how energy deficiency contributes to hypertrophic cardiomyopathy (HCM) development.

Neuroforensomics: metabolites as valuable biomarkers in cerebrospinal fluid of lethal traumatic brain injuries

Traumatic brain injury (TBI) is a ubiquitous, common sequela of accidents with an annual prevalence of several million cases worldwide. In forensic pathology, structural proteins of the cellular compartments of the CNS in serum and cerebrospinal fluid (CSF) have been predominantly used so far as markers of an acute trauma reaction for the biochemical assessment of neuropathological changes after TBI. The analysis of endogenous metabolites offers an innovative approach that has not yet been considered widely in the assessment of causes and circumstances of death, for example after TBI. The present study, therefore, addresses the question whether the detection of metabolites by liquid-chromatography-mass spectrometry (LC/MS) analysis in post mortem CSF is suitable to identify TBI and to distinguish it from acute cardiovascular control fatalities (CVF). Metabolite analysis of 60 CSF samples collected during autopsies was performed using high resolution (HR)-LC/MS. Subsequent statistical and graphical evaluation as well as the calculation of a TBI/CVF quotient yielded promising results: numerous metabolites were identified that showed significant concentration differences in the post mortem CSF for lethal acute TBI (survival times up to 90 min) compared to CVF. For the first time, this forensic study provides an evaluation of a new generation of biomarkers for diagnosing TBI in the differentiation to other causes of death, here CVF, as surrogate markers for the post mortem assessment of complex neuropathological processes in the CNS ("neuroforensomics").