Metabolic Biomarkers in Heart Failure

Association between antioxidant metabolites and N-terminal fragment brain natriuretic peptides in insulin-resistant individuals

Objectives

Oxidative stress plays a pivotal role in the development of metabolic syndrome, including heart failure and insulin resistance. The N-terminal fragment of brain natriuretic peptide (NT-proBNP) has been associated with heightened oxidative stress in heart failure patients. Yet, its correlation with insulin resistance remains poorly understood. Our objective is to investigate the association between oxidative stress markers and NT-proBNP levels in insulin-resistant individuals.

Methods

In this cross-sectional study involving 393 participants from the Qatar Biobank, clinical and metabolic data were collected, and the association between NT-proBNP and 72 oxidative stress metabolites was compared between insulin-sensitive and insulin-resistant individuals.

Results

Our results showed significantly lower NT-proBNP levels in insulin-resistant individuals (median = 17 pg/ml; interquartile range = 10.3-29) when compared to their insulin-sensitive counterparts (median = 31 pg/ml; interquartile range = 19-57). Moreover, we revealed notable associations between NT-proBNP levels and antioxidant metabolic pathways, particularly those related to glutathione metabolism, in insulin-resistant, but not insulin-sensitive individuals.

Conclusion

The significant decrease in NT-proBNP observed in individuals with insulin resistance may be attributed to a direct or indirect enhancement in glutathione production, which is regarded as a compensatory mechanism against oxidative stress. This study could advance our understanding of the interplay between oxidative stress during insulin resistance and cardiovascular risk, which could lead to novel therapeutic approaches for managing cardiovascular diseases. Further investigations are needed to assess the practical utility of these potential metabolites and understand the causal nature of their association with NT-proBNP in the etiology of insulin resistance.

Thymic Atrophy and Immune Dysregulation in Infants with Complex Congenital Heart Disease

Congenital heart disease (CHD) is the most common birth defect, and up to 50% of infants with CHD require cardiovascular surgery early in life. Current clinical practice often involves thymus resection during cardiac surgery, detrimentally affecting T-cell immunity. However, epidemiological data indicate that CHD patients face an elevated risk for infections and immune-mediated diseases, independent of thymectomy. Hence, we examined whether the cardiac defect impacts thymus function in individuals with CHD. We investigated thymocyte development in 58 infants categorized by CHD complexity. To assess the relationship between CHD complexity and thymic function, we analyzed T-cell development, thymic output, and biomarkers linked to cardiac defects, stress, or inflammation. Patients with highly complex CHD exhibit thymic atrophy, resulting in low frequencies of recent thymic emigrants in peripheral blood, even prior to thymectomy. Elevated plasma cortisol levels were detected in all CHD patients, while high NT-proBNP and IL-6 levels were associated with thymic atrophy. Our findings reveal an association between complex CHD and thymic atrophy, resulting in reduced thymic output. Consequently, thymus preservation during cardiovascular surgery could significantly enhance immune function and the long-term health of CHD patients.

Metabolic Profiling Identifies 1-MetHis and 3-IPA as Potential Diagnostic Biomarkers for Patients With Acute and Chronic Heart Failure With Reduced Ejection Fraction

BACKGROUND

Metabolomics has become a valuable tool for identifying potential new biomarkers and metabolic profiles. It has the potential to improve the diagnosis and prognosis of different phenotypes of heart failure. To generate a distinctive metabolic profile, we assessed and compared the metabolic phenotypes of patients with acute decompensated heart failure (ADHF), patients with chronic heart failure (CHF), and healthy controls.

METHODS

Plasma metabolites were analyzed by liquid-chromatography mass spectrometry/mass spectrometry and the MxP Quant 500 kit in 15 patients with ADHF, 50 patients with CHF (25 with dilated cardiomyopathy, 25 with ischemic cardiomyopathy), and 13 controls.

RESULTS

Of all metabolites identified to be significantly altered, 3-indolepropionic acid and 1-methyl histidine showed the highest concentration differences in ADHF and CHF compared with control. Area under the curve-receiver operating characteristic analysis showed an area under the curve ≥0.8 for 3-indolepropionic acid and 1-methyl histidine, displaying good discrimination capabilities between control and patient cohorts. Additionally, symmetrical dimethylarginine (mean, 1.97±0.61 [SD]; P=0.01) was identified as a suitable biomarker candidate for ADHF and kynurenine (mean, 1.69±0.39 [SD]; P=0.009) for CHF when compared with control, both demonstrating an area under the curve ≥0.85.

CONCLUSIONS

Our study provides novel insights into the metabolic differences between ADHF and CHF and healthy controls. We here identify new metabolites for potential diagnostic and prognostic purposes.

Precision Medicine and the future of Cardiovascular Diseases: A Clinically Oriented Comprehensive Review

Cardiac diseases form the lion's share of the global disease burden, owing to the paradigm shift to non-infectious diseases from infectious ones. The prevalence of CVDs has nearly doubled, increasing from 271 million in 1990 to 523 million in 2019. Additionally, the global trend for the years lived with disability has doubled, increasing from 17.7 million to 34.4 million over the same period. The advent of precision medicine in cardiology has ignited new possibilities for individually personalized, integrative, and patient-centric approaches to disease prevention and treatment, incorporating the standard clinical data with advanced "omics". These data help with the phenotypically adjudicated individualization of treatment. The major objective of this review was to compile the evolving clinically relevant tools of precision medicine that can help with the evidence-based precise individualized management of cardiac diseases with the highest DALY. The field of cardiology is evolving to provide targeted therapy, which is crafted as per the "omics", involving genomics, transcriptomics, epigenomics, proteomics, metabolomics, and microbiomics, for deep phenotyping. Research for individualizing therapy in heart diseases with the highest DALY has helped identify novel genes, biomarkers, proteins, and technologies to aid early diagnosis and treatment. Precision medicine has helped in targeted management, allowing early diagnosis, timely precise intervention, and exposure to minimal side effects. Despite these great impacts, overcoming the barriers to implementing precision medicine requires addressing the economic, cultural, technical, and socio-political issues. Precision medicine is proposed to be the future of cardiovascular medicine and holds the potential for a more efficient and personalized approach to the management of cardiovascular diseases, contrary to the standardized blanket approach.

Multifaceted role of cardiovascular biomarkers

Cardiovascular diseases, a global health issue, claim the lives of many every year. Lifestyle changes and genetic predisposition are the key drivers for the development of CVDs. In many of the patients, the disease is detected at the end stage making heart transplantation the only treatment option. Hence every attempt should be made to identify the risk at an early stage and initiate preventive measures to improve the quality of their life. Biomarkers are one of the critical factors that aid in the early diagnosis of CVDs. More specific and highly sensitive biomarkers have been discovered lately and have been employed for prognosis and diagnosis of CVDs. The present review briefs about the various categories of cardiovascular biomarkers with emphasis on novel biomarkers and discusses the biomarkers employed for different purposes in CVDs. The biomarkers have also helped in identifying COVID-19 patients with increased risk for developing cardiovascular complications. Being non-invasive makes biomarkers advantageous over other methods for evaluating the pathophysiological status of CVDs.

Metabolomics in gestational diabetes mellitus: A review

Gestational diabetes mellitus (GDM), a common complication of pregnancy, is a type of diabetes that is first detected and diagnosed during pregnancy. The incidence of GDM is increasing annually and is associated with many adverse pregnancy outcomes. Early prediction of the risk of GDM and intervention are thus important to reduce adverse pregnancy outcomes. Studies have revealed a correlation between the levels of amino acids, fatty acids, triglycerides, and other metabolites in early pregnancy and the occurrence of GDM. The development of high-throughput technologies used in metabolomics has enabled the detection of changes in the levels of small-molecule metabolites during early pregnancy, which can help reflect the overall physiological and pathological status of the body and explore the underlying mechanisms of the development of GDM. This review sought to summarize current research in this field and provide data for the development of strategies to manage GDM.

Application of Metabolomics in Childhood Leukemia Diagnostics

Metabolomics is a new field of science dealing with the study and analysis of metabolites formed in living cells. The biological fluids used in this test method are: blood, blood plasma, serum, cerebrospinal fluid, saliva and urine. The most popular methods of assessing the composition of metabolites include nuclear magnetic resonance spectroscopy and mass spectrometry (MS) in combination with gas chromatography–MS or liquid chromatography–MS. Metabolomics is used in many areas of medicine. The variability of biochemical processes in neoplastic cells in relation to healthy cells is the starting point for this type of research. The aim of the research currently being carried out is primarily to find biomarkers for quick diagnosis of the disease, assessment of its advancement and treatment effectiveness. The development of metabolomics may also contribute to the individualization of treatment of patients, adjusting drugs depending on the metabolic profile, and thus may improve the effectiveness of therapy, reduce side effects and help to improve the quality of life of patients. Here, we review the current and potential applications of metabolomics, focusing on its use as a biomarker method for childhood leukemia.

Graphic abstract

Role of Gut Microbiome in Cardiovascular Events: A Systematic Review

The gut microbiome helps maintain homeostasis in the body, but what if the gut experiences imbalance? It would lead to dysbiosis - which is involved in multiple diseases, including but not limited to cardiovascular diseases, the most common cause of mortality around the globe. This research paper aims to explain all the possible mechanisms known linking the gut microbiome to the contribution of worsening cardiovascular events. PubMed and Google Scholar were thoroughly explored to learn the role of the gut microbiome in cardiovascular events. A systematic review was performed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines to analyze the possible pathways and the metabolites included in the study. Thirteen review articles were selected based on the assessment of multiple systematic reviews (AMSTAR) and the scale for the assessment of non-systematic review articles (SANRA) checklist scores. In this article, we have discussed the role of the gut microbiome in atherosclerosis, hypertension, metabolic disorders such as diabetes and obesity, coronary artery disease, etc. Various pathways to modify the gut microbiome are also discussed, along with the use of probiotics. Finally, we discussed the role of trimethylamine N-oxide (TMAO), a gut microbiome metabolite, as a biomarker for the prognosis of various diseases. This study concluded that the gut microbiome does play a crucial role in the worsening of cardiovascular diseases and the metabolites of which can be used as biomarkers in the prognosis of cardiovascular events.

Understanding How Heart Metabolic Derangement Shows Differential Stage Specificity for Heart Failure with Preserved and Reduced Ejection Fraction

Heart failure (HF) is a clinical condition defined by structural and functional abnormalities in the heart that gradually result in reduced cardiac output (HFrEF) and/or increased cardiac pressures at rest and under stress (HFpEF). The presence of asymptomatic individuals hampers HF identification, resulting in delays in recognizing patients until heart dysfunction is manifested, thus increasing the chance of poor prognosis. Given the recent advances in metabolomics, in this review we dissect the main alterations occurring in the metabolic pathways behind the decrease in cardiac function caused by HF. Indeed, relevant preclinical and clinical research has been conducted on the metabolite connections and differences between HFpEF and HFrEF. Despite these promising results, it is crucial to note that, in addition to identifying single markers and reliable threshold levels within the healthy population, the introduction of composite panels would strongly help in the identification of those individuals with an increased HF risk. That said, additional research in the field is required to overcome the current drawbacks and shed light on the pathophysiological changes that lead to HF. Finally, greater collaborative data sharing, as well as standardization of procedures and approaches, would enhance this research field to fulfil its potential.

Acylcarnitines: Nomenclature, Biomarkers, Therapeutic Potential, Drug Targets, and Clinical Trials

Acylcarnitines are fatty acid metabolites that play important roles in many cellular energy metabolism pathways. They have historically been used as important diagnostic markers for inborn errors of fatty acid oxidation and are being intensively studied as markers of energy metabolism, deficits in mitochondrial and peroxisomal β -oxidation activity, insulin resistance, and physical activity. Acylcarnitines are increasingly being identified as important indicators in metabolic studies of many diseases, including metabolic disorders, cardiovascular diseases, diabetes, depression, neurologic disorders, and certain cancers. The US Food and Drug Administration-approved drug L-carnitine, along with short-chain acylcarnitines (acetylcarnitine and propionylcarnitine), is now widely used as a dietary supplement. In light of their growing importance, we have undertaken an extensive review of acylcarnitines and provided a detailed description of their identity, nomenclature, classification, biochemistry, pathophysiology, supplementary use, potential drug targets, and clinical trials. We also summarize these updates in the Human Metabolome Database, which now includes information on the structures, chemical formulae, chemical/spectral properties, descriptions, and pathways for 1240 acylcarnitines. This work lays a solid foundation for identifying, characterizing, and understanding acylcarnitines in human biosamples. We also discuss the emerging opportunities for using acylcarnitines as biomarkers and as dietary interventions or supplements for many wide-ranging indications. The opportunity to identify new drug targets involved in controlling acylcarnitine levels is also discussed. SIGNIFICANCE STATEMENT: This review provides a comprehensive overview of acylcarnitines, including their nomenclature, structure and biochemistry, and use as disease biomarkers and pharmaceutical agents. We present updated information contained in the Human Metabolome Database website as well as substantial mapping of the known biochemical pathways associated with acylcarnitines, thereby providing a strong foundation for further clarification of their physiological roles.

The Gut Axis Involvement in Heart Failure: Focus on Trimethylamine N-oxide

A novel pathophysiological model of interest is the association between heart failure (HF) and the gastrointestinal system, the 'gut hypothesis'. The choline and carnitine metabolic by-product, Trimethylamine N-oxide (TMAO) is one of the more prominent molecules associated with the link between HF and the gut. Indeed, TMAO levels are increased in HF populations and higher TMAO levels are associated with poor prognosis, whereas low TMAO levels either at baseline/follow up confer better prognosis. Considering that TMAO levels seem not to be affected by guideline-HF treatment, this model could represent a novel and independent therapeutic target for HF.

Whole Blood Metabolite Profiles Reflect Changes in Energy Metabolism in Heart Failure

A variety of atherosclerosis and cardiovascular disease (ASCVD) phenotypes are tightly linked to changes in the cardiac energy metabolism that can lead to a loss of metabolic flexibility and to unfavorable clinical outcomes. We conducted an association analysis of 31 ASCVD phenotypes and 97 whole blood amino acids, acylcarnitines and derived ratios in the LIFE-Adult (n = 9646) and LIFE-Heart (n = 5860) studies, respectively. In addition to hundreds of significant associations, a total of 62 associations of six phenotypes were found in both studies. Positive associations of various amino acids and a range of acylcarnitines with decreasing cardiovascular health indicate disruptions in mitochondrial, as well as peroxisomal fatty acid oxidation. We complemented our metabolite association analyses with whole blood and peripheral blood mononuclear cell (PBMC) gene-expression analyses of fatty acid oxidation and ketone-body metabolism related genes. This revealed several differential expressions for the heart failure biomarker N-terminal prohormone of brain natriuretic peptide (NT-proBNP) in peripheral blood mononuclear cell (PBMC) gene expression. Finally, we constructed and compared three prediction models of significant stenosis in the LIFE-Heart study using (1) traditional risk factors only, (2) the metabolite panel only and (3) a combined model. Area under the receiver operating characteristic curve (AUC) comparison of these three models shows an improved prediction accuracy for the combined metabolite and classical risk factor model (AUC = 0.78, 95%-CI: 0.76–0.80). In conclusion, we improved our understanding of metabolic implications of ASCVD phenotypes by observing associations with metabolite concentrations and gene expression of the mitochondrial and peroxisomal fatty acid oxidation. Additionally, we demonstrated the predictive potential of the metabolite profile to improve classification of patients with significant stenosis.

Attenuation of Circulating Trimethylamine N-Oxide Prevents the Progression of Cardiac and Renal Dysfunction in a Rat Model of Chronic Cardiorenal Syndrome

Chronic heart failure (HF) frequently causes progressive decline in kidney function, known as cardiorenal syndrome-2 (CRS2). Current treatment options for CRS2 remain unacceptably limited. Trimethylamine-N-oxide (TMAO), a metabolite of gut microbiota, has recently been implicated in the pathogenesis of both HF and chronic kidney disease. Here we examined whether circulating TMAO is elevated in CRS2 and if so, whether attenuation of circulating TMAO would ameliorate the progression of CRS2. Sprague-Dawley rats underwent surgery for myocardial infarction (MI) or sham (week 0) followed by subtotal (5/6) nephrectomy (STNx) or sham at week 4 to induce CRS2 or control. At week 6, MI + STNx rats and control rats received vehicle or 1.0% 3,3-Dimethyl-1-butanol (DMB, a TMAO inhibitor) treatment for 8 weeks. Compared with control rats, MI + STNx rats exhibited elevated serum TMAO at week 6, which was increased further at week 14 but was attenuated by DMB treatment. MI + STNx rats showed cardiac dysfunction as assessed by echocardiography and renal dysfunction as evidenced by increased serum creatinine and urinary kidney injury molecule-1 and decreased creatinine clearance at week 6. The cardiac and renal dysfunction in MI + STNx rats was exacerbated at week 14 but was prevented by DMB treatment. Molecular and histological studies revealed myocyte hypertrophy and increases in interstitial myocardial fibrosis and gene expression of pro-hypertrophic and pro-fibrotic markers in both heart and kidney at week 14, which were accompanied by elevated gene expression of proinflammatory cytokines. The changes in molecular and histological parameters observed in MI + STNx rats were significantly reduced by DMB treatment. These findings suggest that rats with CRS2 have elevated circulating TMAO, which is associated with the exacerbation of cardiac and renal dysfunction. Attenuation of circulating TMAO can ameliorate cardiac and renal injury and prevents the progression of CRS2.

Cardiovascular mechanobiology-a Special Issue to look at the state of the art and the newest insights into the role of mechanical forces in cardiovascular development, physiology and disease

There has been much progress recently in the area of cardiovascular mechanobiology and this Special Issue aims at taking stock. This editorial gives context of the main motivation for this special issue as well as a brief summary of its content.

Trimethylamine/Trimethylamine-N-Oxide as a Key Between Diet and Cardiovascular Diseases

Trimethylamine (TMA) is a gut microbiota-derived metabolite which comes from diets rich of choline, betaine or L-carnitine and could be further converted to Trimethylamine-N-oxide (TMAO) in the liver. As the function of gut microbiota and its metabolites being explored so far, studies suggest that TMAO may be a potential risk factor of cardiovascular diseases independent of other traditional risk factors. However, the precise role of TMAO is controversial as some converse results were discovered. In recent studies, it is hypothesized that TMA may also participate in the progression of cardiovascular diseases and some cytotoxic effect of TMA has been discovered. Thus, exploring the relationship between TMA, TMAO and CVD may bring a novel insight into the diagnosis and therapy of cardiovascular diseases. In this review, we discussed the factors which influence the TMA/TMAO's process of metabolism in the human body. We have also summarized the pathogenic effect of TMA/TMAO in cardiovascular diseases, as well as the limitation of some controversial discoveries.

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.

Performance of a cardiac lipid panel compared to four prognostic scores in chronic heart failure

The cardiac lipid panel (CLP) is a novel panel of metabolomic biomarkers that has previously shown to improve the diagnostic and prognostic value for CHF patients. Several prognostic scores have been developed for cardiovascular disease risk, but their use is limited to specific populations and precision is still inadequate. We compared a risk score using the CLP plus NT-proBNP to four commonly used risk scores: The Seattle Heart Failure Model (SHFM), Framingham risk score (FRS), Barcelona bio-HF (BCN Bio-HF) and Meta-Analysis Global Group in Chronic Heart Failure (MAGGIC) score. We included 280 elderly CHF patients from the Cardiac Insufficiency Bisoprolol Study in Elderly trial. Cox Regression and hierarchical cluster analysis was performed. Integrated area under the curves (IAUC) was used as criterium for comparison. The mean (SD) follow-up period was 81 (33) months, and 95 (34%) subjects met the primary endpoint. The IAUC for FRS was 0.53, SHFM 0.61, BCN Bio-HF 0.72, MAGGIC 0.68, and CLP 0.78. Subjects were partitioned into three risk clusters: low, moderate, high with the CLP score showing the best ability to group patients into their respective risk cluster. A risk score composed of a novel panel of metabolite biomarkers plus NT-proBNP outperformed other common prognostic scores in predicting 10-year cardiovascular death in elderly ambulatory CHF patients. This approach could improve the clinical risk assessment of CHF patients.

Mitochondrial Homeostasis Mediates Lipotoxicity in the Failing Myocardium

Heart failure remains the most common cause of death in the industrialized world. In spite of new therapeutic interventions that are constantly being developed, it is still not possible to completely protect against heart failure development and progression. This shows how much more research is necessary to understand the underlying mechanisms of this process. In this review, we give a detailed overview of the contribution of impaired mitochondrial dynamics and energy homeostasis during heart failure progression. In particular, we focus on the regulation of fatty acid metabolism and the effects of fatty acid accumulation on mitochondrial structural and functional homeostasis.

L-Carnitine and Acylcarnitines: Mitochondrial Biomarkers for Precision Medicine

Biomarker discovery and implementation are at the forefront of the precision medicine movement. Modern advances in the field of metabolomics afford the opportunity to readily identify new metabolite biomarkers across a wide array of disciplines. Many of the metabolites are derived from or directly reflective of mitochondrial metabolism. L-carnitine and acylcarnitines are established mitochondrial biomarkers used to screen neonates for a series of genetic disorders affecting fatty acid oxidation, known as the inborn errors of metabolism. However, L-carnitine and acylcarnitines are not routinely measured beyond this screening, despite the growing evidence that shows their clinical utility outside of these disorders. Measurements of the carnitine pool have been used to identify the disease and prognosticate mortality among disorders such as diabetes, sepsis, cancer, and heart failure, as well as identify subjects experiencing adverse drug reactions from various medications like valproic acid, clofazimine, zidovudine, cisplatin, propofol, and cyclosporine. The aim of this review is to collect and interpret the literature evidence supporting the clinical biomarker application of L-carnitine and acylcarnitines. Further study of these metabolites could ultimately provide mechanistic insights that guide therapeutic decisions and elucidate new pharmacologic targets.

Comprehensive plasma metabolites profiling reveals phosphatidylcholine species as potential predictors for cardiac resynchronization therapy response

Aims

This study aimed to identify the plasma metabolite fingerprint in patients with heart failure and to develop a prediction tool based on differential metabolites for predicting the response to cardiac resynchronization therapy (CRT).

Methods and results

We prospectively recruited 32 healthy individuals and 42 consecutive patients with HF who underwent CRT between January 2018 and January 2019. Peripheral venous blood samples, clinical data, and echocardiographic signatures were collected before CRT implantation. Liquid chromatography‐mass spectrometry was used to perform untargeted metabolites profiling for peripheral plasma under ESI+ and ESI− modes. After 6 month follow‐up, patients were categorized as CRT responders or non‐responders based on the alterations of echocardiographic characteristics. Compared with healthy individuals, patients with HF had distinct metabolomic profiles under both ESI+ and ESI− modes, featuring increased free fatty acids, carnitine, β‐hydroxybutyrate, and dysregulated lipids with heterogeneous alterations such as phosphatidylcholines (PCs) and sphingomyelins. Disparities of baseline metabolomics profile were observed between CRT responders and non‐responders under ESI+ mode but not under ESI− mode. Further metabolites analysis revealed that a group of 20 PCs metabolites under ESI+ mode were major contributors to the distinct profiles between the two groups. We utilized LASSO regression model and identified a panel of four PCs metabolites [including PC (20:0/18:4), PC (20:4/20:0), PC 40:4, and PC (20:4/18:0)] as major predictors for CRT response prediction. Among our whole population (n = 42), receive operating characteristics analysis revealed that the four PCs‐based model could nicely discriminate the CRT responders from non‐responders (area under the curve = 0.906) with a sensitivity of 83.3% and a specificity of 90.0%. Cross‐validation analysis also showed a satisfactory and robust performance of the model with the area under the curve of 0.910 in the training dataset and 0.880 in the testing dataset.

Conclusions

Patients with HF held significantly altered plasma metabolomics profile compared with the healthy individuals. Within the HF group, the non‐responders had a distinct plasma metabolomics profile in contrast to the responders to CRT, which was characterized by increased PCs species. A novel predictive model incorporating four PCs metabolites performed well in identifying CRT non‐responders. These four PCs might severe as potential biomarkers for predicting CRT response. Further validations are needed in multi‐centre studies with larger external cohorts.

Metabolic Modulation and Potential Biomarkers of the Prognosis Identification for Severe Aortic Stenosis after TAVR by a Metabolomics Study

Objectives

To investigate the metabolic profile in patients with aortic stenosis (AS) after transcatheter aortic valve replacement (TAVR) and explore the potential biomarkers to predict prognosis after TAVR based on metabolomics.

Methods and Results

Fifty-nine consecutive AS patients were prospectively recruited. Blood samples from the ascending aorta, coronary sinus, and peripheral vein at before and after TAVR were collected, respectively. Liquid chromatography-mass spectrometry and gas chromatography-mass spectrometry were performed to analyze the metabolic profile before and after TAVR. Influential metabolites were identified by integrating the univariate test, multivariate analysis, and weighted gene coexpression network analysis (WGCNA) algorithm. PLS-DA analysis revealed a significant extremely early (within 30 minutes after TAVR) alterations of metabolites in the ascending aorta, coronary sinus, and peripheral vein. The early (within 7 days after TAVR) changed metabolites in the peripheral vein were involved in purine metabolism, primary bile acid biosynthesis, glycerolipid metabolism, amino sugar and nucleotide sugar metabolism, one carbon pool by folate and alanine, and the aspartate and glutamate metabolism pathway. We used volcano plots to find that the cardiac-specific changed metabolites were enriched to the sphingolipid metabolism pathway after TAVR. Besides, WGCNA algorithm was performed to reveal that arginine and proline metabolites could reflect left ventricle regression to some extent.

Conclusion

This is the first study to reveal systemic and cardiac metabolites changed significantly in patients with AS after TAVR. Some altered metabolites involved in the arginine and proline metabolism pathway in the peripheral vein could predict left ventricle regression, which merited further study.

Optimism, pessimism, and health biomarkers in older couples

OBJECTIVE

Studies have demonstrated the importance of optimism in predicting perceived general health. However, the handful of studies focusing on cardiovascular biomarkers show inconsistent effects. Additionally, no study examined whether spousal levels of optimism and pessimism affect an individual's biological markers of cardiovascular health. Thus, our objectives were to examine whether partners' optimism and pessimism affect individual biological markers, differentiating between between-dyad associations and within-dyad predictive processes.

METHODS

Three waves of the Health and Retirement Study collected in 2006, 2010, and 2014 were used to test actor and partner effects of optimism and pessimism on C-reactive protein (CRP) and high-density lipoprotein. Multilevel longitudinal actor-partner models were used to examine the contribution of a partner's optimism and pessimism to each biomarker, adjusting for respondent's age, sex, depression, body mass index, daily activity levels, and a summary score of respondent's doctor-diagnosed chronic conditions.

RESULTS

Partners' pessimism and optimism levels were moderately associated. Results for within-person effects were all non-significant, both within and across waves. Associations at the between-person level were also non-significant, with the exception of a positive association between husbands' pessimism and their own CRP, and husbands' optimism and their wives' CRP.

CONCLUSIONS

Results suggest that optimism and pessimism may not play a pertinent role in within variability of biomarkers of cardiovascular diseases and have a minor role in predicting to between-person variability of biomarkers of cardiovascular diseases.

Decreases in Circulating Concentrations of Short-Chain Acylcarnitines are Associated with Systolic Function Improvement After Decompensated Heart Failure

Impaired fatty acid metabolism is associated with heart failure (HF) prognosis. However, specific changes in acylcarnitine profiles and their potential clinical value have not been well explored in patients recovering from acute decompensation.This study recruited 79 HF patients hospitalized because of acute decompensation with a left ventricular ejection fraction (LVEF) of < 40% and 51 normal controls. Patients were dichotomized into two groups, namely, the "improved (IMP) " and the "non-improved (NIMP) " groups, as defined by the changes in LVEF from baseline to 12 months after discharge. Mass spectrometry was used to quantify the acylcarnitine concentrations at baseline and 6 and 12 months after discharge. The IMP and NIMP groups contained 42 and 37 patients, respectively. At baseline, HF patients had higher plasma concentrations of specific long-, medium-, and short-chain acylcarnitines compared to normal controls. From baseline to 12 months post-discharge, the IMP group showed significant decreases in long- and short-chain acylcarnitine concentrations, but significant increases in medium-chain acylcarnitines. In the NIMP group, none of the acylcarnitines significantly decreased, and significant increases were noted in long-, medium-, and short-chain acylcarnitines. Generalized estimating equations demonstrated that nine acylcarnitines could discriminate the IMP group from the NIMP group, including three long-chain (C18:1, C16, and C16:1) and six short-chain acylcarnitines (C5, C5-OH, C4, C4:1-DC, C3, and C2). After adjusting for age, the six short-chain acylcarnitines remained significant. Changes in short-chain acylcarnitine profiles are independently associated with the improvement in cardiac systolic function after acute decompensation.

Common Variants in the ARG1 Gene Contribute to the Risk of Dilated Cardiomyopathy in the Han Chinese Population

Background: Arginase I, encoded by the ARG1 gene, is an enzyme that catalyzes the conversion of arginine to ornithine in the urea cycle; mutations in this gene has recently been reported to be associated with dilated cardiomyopathy (DCM) in Pakistan. The present study aimed to investigate the relationship between ARG1 gene mutations and DCM in the Han Chinese population. Methods: A total of 488 DCM cases and 924 matched-healthy controls were recruited. All subjects were genotyped for 12 tag single nucleotide polymorphisms (SNPs) within the ARG1 gene. Genetic association studies, including SNP and haplotype analyses, were performed. Further analyses were conducted to examine the correlations between the associated SNPs and specific clinical characteristics. Results: Only the rs2781666 and rs2781667 loci in the ARG1 gene were found to be significantly associated with DCM compared to the healthy controls. The risk of DCM at both of these loci for T allele carriers was ∼1.42-fold higher than that for carriers of the alternative alleles. There were significant differences in end-diastolic interventricular septal diameter, end-diastolic left ventricular posterior wall diameter, left ventricular end-diastolic diameter, left ventricular end-systolic diameter, and left ventricular ejection fraction among the genotype distributions of both SNPs. Furthermore, we found that the T alleles at the rs2781666 and rs2781667 loci were significantly associated with DCM in gender subgroups and the subgroup of patients <58 years of age. The haplotype T-T (rs2781666-rs2781667) also showed a significant association with DCM. Conclusion: Our results support the hypothesis that alleles and haplotypes of the ARG1 gene are significantly involved in the etiology of DCM in the Han Chinese population, but further research is necessary to elucidate the mechanism governing this association.

A metabolomic study for chronic heart failure patients based on a dried blood spot mass spectrometry approach

Objective: a dried blood spot (DBS) method integrated with direct infusion mass spectrometry (MS) focused on a metabolomic analysis was applied to detect and compare the difference of metabolites between the heart failure (HF) patients and non-HF patients in order to facilitate the early detection of heart failures, provide targeted intervention and offer prognostic insights. Methods: the method we used was an untargeted metabolic approach. The dry blood spot mass spectrometry (DBS) was used to analyze 23 types of amino acids and 26 types of carnitine in blood samples. In the current study, 49 metabolites were selected to establish the PLS-DA model to compare the differences between the 117 HF patients and 118 non-HF patients, which inclined to detect the difference between the two groups. Multiple algorithms were run for selecting different metabolites as potential biomarkers. Ten-fold cross validation method was used to verify and evaluate the selected potential biomarkers. Results: through significant analysis of the microarrays (SAM) and analysis of 9 parameters, 8 metabolites showed significant discrepancies between the HF and non-HF groups. Among these metabolites, the levels of 5 metabolites were increased, and the other 3 metabolites were decreased in the HF group compared with the non-HF group. However, 7 metabolites including Asn, C0, C14, C4DC, C5-OH, C6 and Glu were selected to distinguish the HF group from the non-HF group with specificity and sensitivity of 0.8475 and 0.8974, respectively. Conclusion: metabolomic study for chronic heart failure (CHF) patients based on the dried blood spot mass spectrometry approach would be beneficial to understand the metabolic pathway of HF, and probably work as biomarkers to predict the prognosis of HF and provide the basis for an individualized treatment.

A dried blood spot method with mass spectrometry focused on metabolomics analysis was applied to detect and compare the difference in metabolites between heart failure (HF) patients and non-HF patients in order to facilitate the early detection and treatment of heart failure.

After another decade: LC-MS/MS became routine in clinical diagnostics

Tandem mass spectrometry - especially in combination with liquid chromatography (LC-MS/MS) - is applied in a multitude of important diagnostic niches of laboratory medicine. It is unquestioned in its routine use and is often unreplaceable by alternative technologies. This overview illustrates the development in the past decade (2009-2019) and intends to provide insight into the current standing and future directions of the field. The instrumentation matured significantly, the applications are well understood, and the in vitro diagnostics (IVD) industry is shaping the market by providing assay kits, certified instruments, and the first laboratory automated LC-MS/MS instruments as an analytical core. In many settings the application of LC-MS/MS is still burdensome with locally lab developed test (LDT) designs relying on highly specialized staff. The current routine applications cover a wide range of analytes in therapeutic drug monitoring, endocrinology including newborn screening, and toxicology. The tasks that remain to be mastered are, for example, the quantification of proteins by means of LC-MS/MS and the transition from targeted to untargeted omics approaches relying on pattern recognition/pattern discrimination as a key technology for the establishment of diagnostic decisions.

Novel Findings From a Metabolomics Study of Left Ventricular Diastolic Function: The Bogalusa Heart Study

Background

Diastolic dysfunction is one important causal factor for heart failure with preserved ejection fraction, yet the metabolic signature associated with this subclinical phenotype remains unknown.

Methods and Results

Ultra‐high‐performance liquid chromatography–tandem mass spectroscopy was used to conduct untargeted metabolomic analysis of fasting serum samples in 1050 white and black participants of the BHS (Bogalusa Heart Study). After quality control, 1202 metabolites were individually tested for association with 5 echocardiographic measures of left ventricular diastolic function using multivariable‐adjusted linear regression. Measures of left ventricular diastolic function included the ratio of peak early filling velocity to peak late filling velocity, ratio of peak early filling velocity to mitral annular velocity, deceleration time, isovolumic relaxation time, and left atrial maximum volume index (LAVI). Analyses adjusted for multiple cardiovascular disease risk factors and used Bonferroni‐corrected alpha thresholds. Eight metabolites robustly associated with left ventricular diastolic function in the overall population and demonstrated consistent associations in white and black study participants. N‐formylmethionine (B=0.05; P=1.50×10⁻⁷); 1‐methylhistidine (B=0.05; P=1.60×10⁻⁷); formiminoglutamate (B=0.07; P=5.60×10⁻⁷); N2, N5‐diacetylornithine (B=0.05; P=1.30×10⁻⁷); N‐trimethyl 5‐aminovalerate (B=0.04; P=5.10×10⁻⁶); 5‐methylthioadenosine (B=0.04; P=1.40×10⁻⁵); and methionine sulfoxide (B=0.04; P=3.80×10⁻⁶) were significantly associated with the natural log of the ratio of peak early filling velocity to mitral annular velocity. Butyrylcarnitine (B=3.18; P=2.10×10⁻⁶) was significantly associated with isovolumic relaxation time.

Conclusions

The current study identified novel findings of metabolite associations with left ventricular diastolic function, suggesting that the serum metabolome, and its underlying biological pathways, may be implicated in heart failure with preserved ejection fraction pathogenesis.

The gut microbiome and heart failure: A better gut for a better heart

Despite the development of new drugs and therapeutic strategies, mortality and morbidity related to heart failure (HF) remains high. It is also the leading cause of global mortality. Several concepts have been proposed to explore the underlying pathogenesis of HF, but there is still a strong need for more specific and complementary therapeutic options. In recent years, accumulating evidence has demonstrated that changes in the composition of gut microbiota, referred to as dysbiosis, might play a pivotal role in the development of several diseases, including HF. HF-associated decreased cardiac output, resulting in bowell wall oedema and intestine ischaemia, can alter gut structure, peamibility and function. These changes would favour bacterial translocation, exacerbating HF pathogenesis at least partly through activation of systemic inflammation. Although our knowledge of the precise molecular mechanisms by which gut dysbiosis influance HF is still limited, a growing body of evidence has recently demonstrated the impact of a series of gut microbiome-derived metabolites, such as trimetylamine N-oxide, short-chain fatty acids or secondary bile acids, which have been shown to play critical roles in cardiac health and disease. This review will summarize the role of gut microbiota and its metabolites in the pathogenesis of HF. Current and future preventive and therapeutic strategies to prevent HF by an adequate modulation of the microbiome and its derived metabolites are also discussed.

Mammalian RNA switches: Molecular rheostats in gene regulation, disease, and medicine

Alteration of RNA structure by environmental signals is a fundamental mechanism of gene regulation. For example, the riboswitch is a noncoding RNA regulatory element that binds a small molecule and causes a structural change in the RNA, thereby regulating transcription, splicing, or translation of an mRNA. The role of riboswitches in metabolite sensing and gene regulation in bacteria and other lower species was reported almost two decades ago, but riboswitches have not yet been discovered in mammals. An analog of the riboswitch, the protein-directed RNA switch (PDRS), has been identified as an important regulatory mechanism of gene expression in mammalian cells. RNA-binding proteins and microRNAs are two major executors of PDRS via their interaction with target transcripts in mammals. These protein-RNA interactions influence cellular functions by integrating environmental signals and intracellular pathways from disparate stimuli to modulate stability or translation of specific mRNAs. The discovery of a riboswitch in eukaryotes that is composed of a single class of thiamine pyrophosphate (TPP) suggests that additional ligand-sensing RNAs may be present to control eukaryotic or mammalian gene expression. In this review, we focus on protein-directed RNA switch mechanisms in mammals. We offer perspectives on the potential discovery of mammalian protein-directed and compound-dependent RNA switches that are related to human disease and medicine.

Reductions in gut microbiota‑derived metabolite trimethylamine N‑oxide in the circulation may ameliorate myocardial infarction‑induced heart failure in rats, possibly by inhibiting interleukin‑8 secretion

Myocardial infarction (MI) is a common cause of chronic heart failure (HF). Increasing evidence has revealed that trimethylamine N‑oxide (TMAO), a gut‑microbiota‑derived metabolite, contributes to the pathogenesis of cardiovascular disease by promoting inflammation. Elevated levels of circulating TMAO have been reported in patients following MI and were associated with unfavorable outcomes. The present study examined whether reductions in circulating TMAO could attenuate the progression of HF in rats following MI. Sprague‑Dawley rats underwent coronary ligation to induce MI or a sham operation. Echocardiography confirmed MI and cardiac dysfunction one day following coronary ligation. MI and sham rats were then treated with either vehicle (tap water) or 1.0% 3,3‑dimethyl‑1‑butanol (DMB, a trimethylamine formation inhibitor) in tap water, for 8 weeks. At the end of the experiment, TMAO plasma levels were markedly elevated in vehicle‑treated MI rats compared with vehicle‑treated sham rats; however, TMAO plasma levels were reduced in DMB‑treated MI rats compared with vehicle‑treated MI rats. Both MI groups exhibited cardiac hypertrophy, lung congestion, left ventricular remodeling and impaired cardiac function, according to the results of anatomical analysis, echocardiography and left ventricular hemodynamics; however, these manifestations of MI‑induced HF were significantly improved in DMB‑treated MI rats compared with vehicle‑treated MI rats. The plasma levels of the chemokine interleukin (IL)‑8, and cardiac expression of IL‑8 and its receptors were significantly increased in vehicle‑treated MI rats compared with vehicle‑treated sham rats; however, these were normalized in DMB‑treated MI rats. In addition, elevated TMAO plasma level was positively correlated with increased IL‑8 plasma level in MI groups. Notably, DMB treatment of sham rats also reduced plasma TMAO, but did not alter other parameters. These results indicated that reducing circulating TMAO may ameliorate the development of chronic HF following MI in rats, potentially by inhibiting IL‑8 secretion. The results from the present study suggested that inhibition of TMAO synthesis may be considered as a novel therapeutic approach for the prevention and treatment of patients with chronic MI‑induced HF.

Effect of Grape Pomace Polyphenols With or Without Pectin on TMAO Serum Levels Assessed by LC/MS-Based Assay: A Preliminary Clinical Study on Overweight/Obese Subjects

Growing evidence suggests that trimethylamine N-oxide (TMAO) is recognized as a biomarker of increased cardiovascular risk. So far, the evaluation of TMAO serum levels in the clinical practice is limited due to the lack of developing new facile methods with reduced limitations. However, few approaches were achieved to determine TMAO in serum by using mass spectrometry-based technique, some limitations were reported including the use of internal standards. Therefore, in this work, a liquid chromatography-mass spectrometry (LC/MS) based-assay was developed to evaluate the effect of grape pomace extract (Taurisolo^®, group A) or Taurisolo^®+pectin (group B) on TMAO serum levels in a cohort of overweight/obese subjects. The serum levels of TMAO have been assessed before and after treatment, through LC/MS analysis. After 8-week treatment, in both intervention groups TMAO serum levels significantly decreased (-78.58% p = 0.006 and -76.76% p = 0.001, group A and group B, respectively). Moreover, we performed several analyses aimed to validate the LC/MS method we used. The method has high precision (% C.V = from 12.12 to 3.92% and from 8.25 to 1.07% for intraday and interday, respectively) and accuracy (% bias = from -5.52 to 0.5% and from -1.42 to 3.08% for intraday and interday, respectively). TMAO recoveries from serum ranged from 99 to 97%; LOD: 2 ng/ml and LOQ: 6 ng/ml. In conclusion, we demonstrated the efficacy of a novel nutraceutical formulation in reducing TMAO serum levels in high cardiovascular risk-subjects, and proposed a useful, versatile and rapid LC/MS method for identification and quantization of TMAO, without the use of marked/isotopic internal standards. It, thus, may represent a novel and practical method with applications in clinical practice and nutraceutical research. Clinical Trial Registration: This study is listed on the ISRCTN registry with ID ISRCTN10794277 (doi: 10.1186/ISRCTN10794277).

Gut microbiota signatures and lipids metabolism profiles by exposure to polyene phosphatidylcholine

The aim of the study was to address the causality links and identify specific features of the gut microbiota signatures contributing to host lipids metabolism in the presence or absence of polyene phosphatidylcholine (PPC) administration, and evaluate potential risk of PPC consumption. About 20 C57BL/6J mice were randomly allocated into two groups, normal diet group (CK) and PPC administration group (205.2 mg/kg). Compared with CK group, the contents of unsaturated fatty acids were increased and the saturated fatty acids were decreased in PPC group. The content of free fatty acids (FFA) and lipopolysaccharides (LPS) were significantly decreased (P < 0.05), and expression of carnitine palmitoyltransferase 1A (CPT1A), cluster of differentiation 36 (CD36), liver fatty acid binding protein (L-FABP), fatty acid transport protein 5 (FATP5), and fatty acid synthase (FASN) were significantly decreased in the mRNA and protein levels after treated by PPC (P < 0.05, P < 0.01). Also, we found that acetic acid in feces was significantly increased after consumption of PPC (P < 0.05). After PPC administration the relative abundances of Firmicutes and Clostridia were increased within the phylum level and the class level, respectively. Microbial abundances in genus level were dominated by Lachnospiraceae and Lachnospiraceae_NK4A136_group, whereas the proportion of sequences assigned to Bacteroidetes within the phylum level, class Bacteroidias and Mollicutes, order Anaeroplasmatalesl, genus Bacteroidales_S24-7_group were decreased in metagenomes of treated group with PPC and did not significantly influence on the accumulation of trimethylamine-N-oxide (TMAO). This study revealed that intake of PPC could regulate the gut microbiota signatures and lipids metabolism in mice without TMAO accumulations. © 2019 BioFactors, 45(3):439-449, 2019.

Mechanisms of Cardiovascular Disease in the Setting of HIV Infection

Although the initial reports of increased cardiovascular (CV) disease in the setting of advanced AIDS were reported approximately 30 years ago, advances in antiretroviral therapy and immediate initiation of therapy on diagnosis have transformed what was once a deadly infectious disease into a chronic health condition. Accordingly, the types of CV diseases occurring in HIV have shifted from pericardial effusions and dilated cardiomyopathy to atherosclerosis and heart failure. The underlying pathophysiology of HIV-associated CV disease remains poorly understood, partly because of the rapidly evolving nature of HIV treatment and because clinical endpoints take many years to develop. The gut plays an important role in the early pathogenesis of HIV infection as HIV preferentially infects CD4+ T cells, 80% of which are located in gut mucosa. The loss of these T cells damages gut mucosa resulting in increased gut permeability and microbial translocation, which incites chronic inflammation and immune activation. Antiretroviral therapy does not cure HIV infection and immune abnormalities persist. These abnormalities correlate with mortality and CV events. The effects of antiretroviral therapy on CV risk are complex; treatment reduces inflammation and other markers of CV risk but induces lipid abnormalities, most commonly hypertriglyceridemia. On a molecular level, monocytes/macrophages, platelet reactivity, and immune cell activation, which play a role in the general population, may be heightened in the setting of HIV and contribute to HIV-associated atherosclerosis. Chronic inflammation represents an inviting therapeutic target in HIV, as it does in uninfected persons with atherosclerosis.