Differential effects of arginine methylation on diastolic dysfunction and disease progression in patients with chronic systolic heart failure

Effects of short-term moderate intensity exercise on the serum metabolome in older adults: a pilot randomized controlled trial

BACKGROUND

We previously reported changes in the serum metabolome associated with impaired myocardial relaxation in an asymptomatic older community cohort. In this prospective parallel-group randomized control pilot trial, we subjected community adults without cardiovascular disease to exercise intervention and evaluated the effects on serum metabolomics.

METHODS

Between February 2019 to November 2019, thirty (83% females) middle-aged adults (53 ± 4 years) were randomized with sex stratification to either twelve weeks of moderate-intensity exercise training (Intervention) (n = 15) or Control (n = 15). The Intervention group underwent once-weekly aerobic and strength training sessions for 60 min each in a dedicated cardiac exercise laboratory for twelve weeks (ClinicalTrials.gov: NCT03617653). Serial measurements were taken pre- and post-intervention, including serum sampling for metabolomic analyses.

RESULTS

Twenty-nine adults completed the study (Intervention n = 14; Control n = 15). Long-chain acylcarnitine C20:2-OH/C18:2-DC was reduced in the Intervention group by a magnitude of 0.714 but increased in the Control group by a magnitude of 1.742 (mean difference -1.028 age-adjusted p = 0.004). Among Controls, alanine correlated with left ventricular mass index (r = 0.529, age-adjusted p = 0.018) while aspartate correlated with Lateral e' (r = -764, age-adjusted p = 0.016). C20:3 correlated with E/e' ratio fold-change in the Intervention group (r = -0.653, age-adjusted p = 0.004). Among Controls, C20:2/C18:2 (r = 0.795, age-adjusted p = 0.005) and C20:2-OH/C18:2-DC fold-change (r = 0.742, age-adjusted p = 0.030) correlated with change in E/A ratio.

CONCLUSIONS

Corresponding relationships between serum metabolites and cardiac function in response to exercise intervention provided pilot observations. Future investigations into cellular fuel oxidation or central carbon metabolism pathways that jointly impact the heart and related metabolic systems may be critical in preventive trials.

Hybrid Bayesian Optimization-Based Graphical Discovery for Methylation Sites Prediction

Protein methylation is one of the most important reversible post-translational modifications (PTMs), playing a vital role in the regulation of gene expression. Protein methylation sites serve as biomarkers in cardiovascular and pulmonary diseases, influencing various aspects of normal cell biology and pathogenesis. Nonetheless, the majority of existing computational methods for predicting protein methylation sites (PMSP) have been constructed based on protein sequences, with few methods leveraging the topological information of proteins. To address this issue, we propose an innovative framework for predicting Methylation Sites using Graphs (GraphMethySite) that employs graph convolution network in conjunction with Bayesian Optimization (BO) to automatically discover the graphical structure surrounding a candidate site and improve the predictive accuracy. In order to extract the most optimal subgraphs associated with methylation sites, we extend GraphMethySite by coupling it with a hybrid Bayesian optimization (together named GraphMethySite +) to determine and visualize the topological relevance among amino-acid residues. We evaluated our framework on two extended protein methylation datasets, and empirical results demonstrate that it outperforms existing state-of-the-art methylation prediction methods.

L-arginine and Its Derivatives Correlate with Exercise Capacity in Patients with Advanced Heart Failure

Methylated arginine metabolites interrupt nitric oxide synthesis, which can result in endothelium dysfunction and inadequate vasodilation. Since little is known about the dynamics of arginine derivatives in patients with heart failure (HF) during physical exercise, we aimed to determine this as well as its impact on the patient outcomes. Fifty-one patients with HF (left ventricle ejection fraction-LVEF ≤ 35%, mean 21.7 ± 5.4%) underwent the cardiopulmonary exercise test (CPET). Plasma concentrations of L-arginine, citrulline, ornithine, asymmetric dimethylarginine (ADMA), and symmetric dimethylarginine (SDMA) were measured before and directly after CPET. All patients were followed for a mean of 23.5 ± 12.6 months. The combined endpoint was: any death, urgent heart transplantation, or urgent LVAD implantation. L-arginine concentrations increased significantly after CPET (p = 0.02), when ADMA (p = 0.01) and SDMA (p = 0.0005) decreased. The parameters of better exercise capacity were positively correlated with post-CPET concentration of L-arginine and inversely with post-CPET changes in ADMA, SDMA, and baseline and post-CPET SDMA concentrations. Baseline and post-CPET SDMA concentrations increased the risk of endpoint occurrence (HR 1.02, 95% CI 1.009–1.03, p = 0.04 and HR 1.02, 95% CI 1.01–1.03, p = 0.02, respectively). In conclusion, in patients with HF, extensive exercise is accompanied by changes in arginine derivatives that can reflect endothelium function. These observations may contribute to the explanation of the pathophysiology of exercise intolerance in HF.

Blood metabolomes as non-invasive biomarkers and targets of metabolic interventions for doxorubicin and trastuzumab-induced cardiotoxicity

This study aimed to identify the alterations of blood metabolome levels and their association with cardiac dysfunction and cardiac injury following treatment with doxorubicin and trastuzumab. Eight-week-old male Wistar rats were divided into four groups (n = 6 per group) to receive intraperitoneal injection with either: (1) 1 mL of normal saline solution (NSS) at days 0, 4, 8, 15, 22, and 29 (control group for doxorubicin); (2) 3 mg/kg/day of doxorubicin at days 0, 4, 8, 15, 22, and 29 (doxorubicin group); (3) 1 mL of NSS at days 0-6 (control group for trastuzumab); or (4) 4 mg/kg/day of trastuzumab at days 0-6 (trastuzumab group). Four days after the last injected dose, cardiac function was determined. The rats were then euthanized to collect venous blood and the heart for the quantification of 107 serum and 100 cardiac metabolomes using mass spectrometry-based targeted metabolomics. We observed strong relationships between 72 cardiac versus 61 serum metabolomes in doxorubicin and trastuzumab groups. Moreover, significant correlations between cardiac function and the cardiac injury biomarker versus 28 and 58 serum metabolomes were revealed in doxorubicin and trastuzumab-treated rats, respectively. Interestingly, the patterns of both serum and cardiac metabolome alterations differed between doxorubicin and trastuzumab groups. Our findings emphasize the potential role of the constituents of the blood metabolome as non-invasive biomarkers to assess severity and prognosis of heart failure induced by doxorubicin and trastuzumab. These findings may contribute to the development of metabolic-targeted therapy specific for cardioprotection during different phases of cancer treatment.

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.

Laboratory and Metabolomic Fingerprint in Heart Failure with Preserved Ejection Fraction: From Clinical Classification to Biomarker Signature

Heart failure with preserved ejection fraction (HFpEF) remains a poorly characterized syndrome with many unknown aspects related to different patient profiles, various associated risk factors and a wide range of aetiologies. It comprises several pathophysiological pathways, such as endothelial dysfunction, myocardial fibrosis, extracellular matrix deposition and intense inflammatory system activation. Until now, HFpEF has only been described with regard to clinical features and its most commonly associated risk factors, disregarding all biological mechanisms responsible for cardiovascular deteriorations. Recently, innovations in laboratory and metabolomic findings have shown that HFpEF appears to be strictly related to specific cells and molecular mechanisms' dysregulation. Indeed, some biomarkers are efficient in early identification of these processes, adding new insights into diagnosis and risk stratification. Moreover, recent advances in intermediate metabolites provide relevant information on intrinsic cellular and energetic substrate alterations. Therefore, a systematic combination of clinical imaging and laboratory findings may lead to a 'precision medicine' approach providing prognostic and therapeutic advantages. The current review reports traditional and emerging biomarkers in HFpEF and it purposes a new diagnostic approach based on integrative information achieved from risk factor burden, hemodynamic dysfunction and biomarkers' signature partnership.

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.

Role of Posttranslational Modifications of Proteins in Cardiovascular Disease

Cardiovascular disease (CVD) has become a leading cause of mortality and morbidity globally, making it an urgent concern. Although some studies have been performed on CVD, its molecular mechanism remains largely unknown for all types of CVD. However, recent in vivo and in vitro studies have successfully identified the important roles of posttranslational modifications (PTMs) in various diseases, including CVD. Protein modification, also known as PTMs, refers to the chemical modification of specific amino acid residues after protein biosynthesis, which is a key process that can influence the activity or expression level of proteins. Studies on PTMs have contributed directly to improving the therapeutic strategies for CVD. In this review, we examined recent progress on PTMs and highlighted their importance in both physiological and pathological conditions of the cardiovascular system. Overall, the findings of this review contribute to the understanding of PTMs and their potential roles in the treatment of CVD.

Metabolic Snapshot of Plasma Samples Reveals New Pathways Implicated in SARS-CoV-2 Pathogenesis

Despite the scientific and human efforts to understand COVID-19, there are questions still unanswered. Variations in the metabolic reaction to SARS-CoV-2 infection could explain the striking differences in the susceptibility to infection and the risk of severe disease. Here, we used untargeted metabolomics to examine novel metabolic pathways related to SARS-CoV-2 susceptibility and COVID-19 clinical severity using capillary electrophoresis coupled to a time-of-flight mass spectrometer (CE-TOF-MS) in plasma samples. We included 27 patients with confirmed COVID-19 and 29 healthcare workers heavily exposed to SARS-CoV-2 but with low susceptibility to infection ("nonsusceptible"). We found a total of 42 metabolites of SARS-CoV-2 susceptibility or COVID-19 clinical severity. We report the discovery of new plasma biomarkers for COVID-19 that provide mechanistic explanations for the clinical consequences of SARS-CoV-2, including mitochondrial and liver dysfunction as a consequence of hypoxemia (citrulline, citric acid, and 3-aminoisobutyric acid (BAIBA)), energy production and amino acid catabolism (phenylalanine and histidine), and endothelial dysfunction and thrombosis (citrulline, asymmetric dimethylarginine (ADMA), and 2-aminobutyric acid (2-AB)), and we found interconnections between these pathways. In summary, in this first report several metabolic pathways implicated in SARS-CoV-2 susceptibility and COVID-19 clinical progression were found by CE-MS based metabolomics that could be developed as biomarkers of COVID-19.

Metabolic endophenotype associated with right ventricular glucose uptake in pulmonary hypertension

Alterations in metabolism and bioenergetics are hypothesized in the mechanisms leading to pulmonary vascular remodeling and heart failure in pulmonary hypertension (PH). To test this, we performed metabolomic analyses on 30 PH individuals and 12 controls. Furthermore, using 2-[18F]fluoro-2-deoxy-D-glucose positron emission tomography, we dichotomized PH patients into metabolic phenotypes of high and low right ventricle (RV) glucose uptake and followed them longitudinally. In support of metabolic alterations in PH and its progression, the high RV glucose group had higher RV systolic pressure (p < 0.001), worse RV function as measured by RV fractional area change and peak global longitudinal strain (both p < 0.05) and may be associated with poorer outcomes (33% death or transplantation in the high glucose RV uptake group compared to 7% in the low RV glucose uptake group at five years follow-up, log-ranked p = 0.07). Pathway enrichment analysis identified key metabolic pathways including fructose catabolism, arginine-nitric oxide metabolism, tricarboxylic acid cycle, and ketones metabolism. Integrative human protein-protein interactome network analysis of metabolomic and transcriptomic data identified key pathobiological pathways: arginine biosynthesis, tricarboxylic acid cycle, purine metabolism, hypoxia-inducible factor 1, and apelin signaling. These findings identify a PH metabolomic endophenotype, and for the first time link this to disease severity and outcomes.

The Correlation between Gut Microbiota and Serum Metabolomic in Elderly Patients with Chronic Heart Failure

OBJECTIVE

Chronic heart failure (CHF) refers to a state of persistent heart failure that can be stable, deteriorated, or decompensated. The mechanism and pathogenesis of myocardial remodeling remain unknown. Based on 16S rDNA sequencing and metabolomics technology, this study analyzed the gut microbiota and serum metabolome in elderly patients with CHF to provide new insights into the microbiota and metabolic phenotypes of CHF.

METHODS

Blood and fecal samples were collected from 25 elderly patients with CHF and 25 healthy subjects. The expression of inflammatory factors in blood was detected by ELISA. 16S rDNA sequencing was used to analyze the changes in microorganisms in the samples. The changes of small molecular metabolites in serum samples were analyzed by LC-MS/MS. Spearman correlation coefficients were used to analyze the correlation between gut microbiota and serum metabolites.

RESULTS

Our results showed that the IL-6, IL-8, and TNF-α levels were significantly increased, and the IL-10 level was significantly decreased in the elderly patients with CHF compared with the healthy subjects. The diversity of the gut microbiota was decreased in the elderly patients with CHF. Moreover, Escherichia Shigella was negatively correlated with biocytin and RIBOFLAVIN. Haemophilus was negatively correlated with alpha-lactose, cellobiose, isomaltose, lactose, melibiose, sucrose, trehalose, and turanose. Klebsiella was positively correlated with bilirubin and ethylsalicylate. Klebsiella was negatively correlated with citramalate, hexanoylcarnitine, inosine, isovalerylcarnitine, methylmalonate, and riboflavin.

CONCLUSION

The gut microbiota is simplified by the disease, and serum small-molecule metabolites evidently change in elderly patients with CHF. Serum and fecal biomarkers could be used for elderly patients with CHF screening.

Plasmatic Dimethylarginines in Dogs With Myxomatous Mitral Valve Disease

Plasmatic dimethylarginines, asymmetric dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA) are considered biomarkers of endothelial and renal dysfunction, respectively, in humans. We hypothesize that plasmatic concentration of dimethylarginines in dogs with myxomatous mitral valve disease (MMVD) is influenced by heart disease stage. Eighty-five client-owned dogs with MMVD, including 39, 19, and 27 dogs in ACVIM stages B1, B2, and C+D, respectively, and a control group of 11 clinically healthy dogs were enrolled. A prospective, multicentric, case-control study was performed. Each dog underwent a complete clinical examination, arterial blood pressure measurement, thoracic radiography, six-lead standard electrocardiogram, transthoracic echocardiography, CBC, biochemical profile, and urinalysis. Plasmatic concentration of dimethylarginines was determined through high-performance liquid chromatography coupled with tandem mass spectrometry. Median ADMA was significantly increased in dogs of group C+D (2.5 μmol/L [2.1–3.0]) compared to those of group B1 (1.8 μmol/L [1.6–2.3]; p < 0.001) and healthy dogs (1.9 μmol/L [1.7–2.3]; p = 0.02). Median SDMA was significantly increased in dogs of group C+D (0.7 μmol/L [0.5–0.9]) compared to those of groups B1 (0.4 μmol/L [0.3–0.5]; p < 0.001), B2 (0.4 μmol/L [0.3–0.6]; p < 0.01), and the control group (0.4 μmol/L [0.35–0.45]; p = 0.001). In the final multivariable analysis, ADMA and SDMA were significantly associated with left atrium to aorta ratio (p < 0.001), and creatinine (p < 0.001), respectively. Increased plasmatic concentrations of dimethylarginines suggest a possible role as biomarkers of disease severity in dogs with decompensated MMVD.

Metabolomic Profiling of Adults with Congenital Heart Disease

Metabolomic analysis may provide an integrated assessment in genetically and pathologically heterogeneous populations. We used metabolomic analysis to gain mechanistic insight into the small and diverse population of adults with congenital heart disease (ACHD). Consecutive ACHD patients seen at a single institution were enrolled. Clinical variables and whole blood were collected at regular clinical visits. Stored plasma samples were analyzed for the concentrations of 674 metabolites and metabolic markers using mass spectrometry with internal standards. These samples were compared to 28 simultaneously assessed healthy non-ACHD controls. Principal component analysis and multivariable regression modeling were used to identify metabolites associated with clinical outcomes in ACHD. Plasma from ACHD and healthy control patients differed in the concentrations of multiple metabolites. Differences between control and ACHD were greater in number and in degree than those between ACHD anatomic groups. A metabolite cluster containing amino acids and metabolites of amino acids correlated with negative clinical outcomes across all anatomic groups. Metabolites in the arginine metabolic pathway, betaine, dehydroepiandrosterone, cystine, 1-methylhistidine, serotonin and bile acids were associated with specific clinical outcomes. Metabolic markers of disease may both be useful as biomarkers for disease activity and suggest etiologically related pathways as possible targets for disease-modifying intervention.

Effects of AGXT2 variants on blood pressure and blood sugar among 750 older Japanese subjects recruited by the complete enumeration survey method

Background

Alanine:glyoxylate aminotransferase 2 (AGXT2; EC 2.6.1.44) is the only enzyme that degrades the R-form of 3-aminoisobutyrate, an intermediate metabolite of thymine. AGXT2, as well as diaminoarginine dimethylaminohydrolase 1 (DDAH1; EC 3.5.3.18), works as an enzyme that degrades asymmetric dimethylarginine (ADMA), which competitively inhibits the nitric oxide synthase family. Thus, these two enzyme activities may change vascular vulnerability for a lifetime via the nitric oxide (NO) system. We investigated the association between vascular conditions and diseases such as hypertension and diabetes mellitus and polymorphisms of these two genes in 750 older Japanese subjects (mean age ± standard deviation, 77.0 ± 7.6 years) recruited using the complete enumeration survey method in the Nakayama study. Demographic and biochemical data, such as blood pressure (BP) and casual blood sugar (CBS), were obtained. Four functional single nucleotide polymorphisms (SNPs; rs37370, rs37369, rs180749, and rs16899974) of AGXT2 and one functional insertion/deletion polymorphism in the promotor region with four SNPs (rs307894, rs669173, rs997251, and rs13373844) of DDAH1 were investigated. Plasma ADMA was also analyzed in 163 subjects.

Results

The results of multiple regression analysis showed that a loss of the functional haplotype of AGXT2, CAAA, was significantly positively correlated with BP (systolic BP, p = 0.034; diastolic BP, p = 0.025) and CBS (p = 0.021). No correlation was observed between DDAH1 and either BP or CBS. ADMA concentrations were significantly elevated in subjects with two CAAA haplotypes compared with subjects without the CAAA haplotype (p = 0.033).

Conclusions

Missense variants of AGXT2, but not DDAH1, may be related to vulnerability to vascular diseases such as hypertension and DM via the NO system.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-021-07612-3.

Metabolomic Profiles and Heart Failure Risk in Black Adults: Insights From the Jackson Heart Study

BACKGROUND

Heart failure (HF) is a heterogeneous disease characterized by significant metabolic disturbances; however, the breadth of metabolic dysfunction before the onset of overt disease is not well understood. The purpose of this study was to determine the association of circulating metabolites with incident HF to uncover novel metabolic pathways to disease.

METHODS

We performed targeted plasma metabolomic profiling in a deeply phenotyped group of Black adults from the JHS (Jackson Heart Study; n=2199). We related metabolites associated with incident HF to established etiological mechanisms, including increased left ventricular mass index and incident coronary heart disease. Furthermore, we evaluated differential associations of metabolites with HF with preserved ejection fraction versus HF with reduced ejection fraction.

RESULTS

Metabolites associated with incident HF included products of posttranscriptional modifications of RNA, as well as polyamine and nitric oxide metabolism. A subset of metabolite-HF associations was independent of well-established HF pathways such as increased left ventricular mass index and incident coronary heart disease and included homoarginine (per 1 SD increase in metabolite level, hazard ratio, 0.77; P=1.2×10-3), diacetylspermine (hazard ratio, 1.34; P=3.4×10-3), and uridine (hazard ratio, 0.79; P, 3×10-4). Furthermore, metabolites involved in pyrimidine metabolism (orotic acid) and collagen turnover (N-methylproline) among others were part of a distinct metabolic signature that differentiated individuals with HF with preserved ejection fraction versus HF with reduced ejection fraction.

CONCLUSIONS

The integration of clinical phenotyping with plasma metabolomic profiling uncovered novel metabolic processes in nontraditional disease pathways underlying the heterogeneity of HF development in Black adults.

Prognostic Value of Asymmetric Dimethylarginine in Patients with Heart Failure: A Systematic Review and Meta-analysis

Objective

Asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide (NO) synthesis, is reported to be a risk factor for cardiovascular disease. The purpose of the present study is to investigate whether ADMA is an independent predictor for future mortality and adverse clinical events among patients with heart failure (HF).

Methods

Electronic literature databases (Central, MEDLINE, and Embase) were searched for relevant observational studies on the prognostic value of ADMA in HF patients published before January 2019. Pooled hazard ratios (HRs) or odds ratio and the corresponding 95% confidence interval (CI) were calculated for risk evaluation.

Results

10 studies with 2195 participants were identified and analyzed. The pooled HR of composite clinical events for the highest vs. lowest quartiles from categorical variable results was 1.34 (95% CI: 1.15-1.57, P < 0.001, I² = 0%), which is 1.31 (95% CI: 1.10-1.55, P < 0.005, I² = 0%) in the subgroup of acute decompensated HF. The pooled HR of composite clinical events from continuous variable results was 1.41 (95% CI: 1.21-1.63, P < 0.001, I² = 21.9%), with 0.1 μM increment accounting for the increasing 25% risk for composite adverse clinical events. The pooled HR for all-cause mortality was 2.38 (95% CI: 1.48-3.82, P < 0.001, I² = 0%) after sensitivity analysis. Two studies reporting the HR of inhospital mortality in HF patients regarded it as a prognostic indicator, with categorical variable HR as 1.26 (95% CI: 1.07-1.84, P < 0.05) and continuous variable OR as 2.15 (95% CI: 1.17–4.29, P < 0.05).

Conclusions

ADMA is an independent predictor for composite clinical outcomes among HF patients with both short-term and long-term prognostic value.

Protein Arginine Methyltransferases in Cardiovascular and Neuronal Function

The methylation of arginine residues by protein arginine methyltransferases (PRMTs) is a type of post-translational modification which is important for numerous cellular processes, including mRNA splicing, DNA repair, signal transduction, protein interaction, and transport. PRMTs have been extensively associated with various pathologies, including cancer, inflammation, and immunity response. However, the role of PRMTs has not been well described in vascular and neurological function. Aberrant expression of PRMTs can alter its metabolic products, asymmetric dimethylarginine (ADMA), and symmetric dimethylarginine (SDMA). Increased ADMA levels are recognized as an independent risk factor for cardiovascular disease and mortality. Recent studies have provided considerable advances in the development of small-molecule inhibitors of PRMTs to study their function under normal and pathological states. In this review, we aim to elucidate the particular roles of PRMTs in vascular and neuronal function as a potential target for cardiovascular and neurological diseases.

Soluble angiotensin converting enzyme 2 levels in chronic heart failure is associated with decreased exercise capacity and increased oxidative stress-mediated endothelial dysfunction

The aim of this study was to explore the relationship between serum soluble angiotensin converting enzyme 2 (sACE2), parameters of cardiopulmonary exercise testing and plasma asymmetric dimethylarginine (ADMA), a marker of oxidative stress-induced endothelial dysfunction. This has not been previously evaluated. We assessed 50 consecutive ambulatory patients with chronic systolic heart failure and left ventricular ejection fraction (LVEF) ≤45%. Their blood samples were collected for sACE2 and ADMA tests before they underwent symptom-limited cardiopulmonary exercise testing and transthoracic echocardiography. The majority of our study subjects had New York Heart Association functional class II (74%) and III (18%) presentation, and 42% of patients had ischemic etiology. Median sACE2 activity was 10.36 (7.00-14.47) ng/mL and mean ADMA was 0.90 ± 0.22. sACE2 activity was inversely correlated with pVO₂ (r = -0.42, P = 0.00283), exercise time (r = -0.35, P = 0.0138) and LVEF (r = -0.548, P < 0.001), and positively correlated with VE/VCO₂ slope (r = 0.294, P = 0.0405), ΔDBP (r = 0.315, P = 0.0278), mitral E/Ea ratio (r = 0.442, P = 0.00158) and ADMA levels (r = 0.351, P = 0.0134). Meanwhile, we observed a negative correlation between ADMA and pVO₂ (r = -0.424, P = 0.00227) and positive correlations between ADMA and VE/VCO₂ slope (r = 0.515, P < 0.001), ΔDBP (r = 0.391, P = 0.00568), mitral E/Ea ratio (r = 0.426, P = 0.00219). In multivariate logistic regression analysis, sACE2 was independently associated with peak oxygen uptake (% predicted) after adjusting for body mass index (BMI) and mitral E/Ea ratio (odds ratio [OR] 0.81 (0.58-0.94), P = 0.041) and associated with oxygen pulse (VO₂/HR) (%) after adjusting for age, gender, BMI and mitral E/Ea ratio (OR 0.83 [0.68-0.95], P = 0.025). Therefore in stable chronic systolic heart failure patients, higher sACE2 activity is independently associated with diminished exercise capacity and correlates with elevated systemic oxidative stress-mediated endothelial dysfunction.

Association of Asymmetric Dimethylarginine and Diastolic Dysfunction in Patients with Hypertrophic Cardiomyopathy

Despite genetic heterogeneity, early manifestation of diastolic dysfunction (DD) is common in hypertrophic cardiomyopathy (HCM). Nitric oxide (NO) may contribute to myocardial relaxation. NO synthases (NOS) use l-arginine (Arg) as a substrate, as asymmetric dimethylarginine (ADMA) is a direct endogenous inhibitor of NOS. This study aimed to analyze the association of Arg and its derivates, i.e., l-homoarginine (hArg), ADMA and symmetric dimethylarginine (SDMA), with DD in HCM patients. In 215 HCM patients (mean age 54 ± 15 years, 58% male) transmitral and mitral annulus velocities were echocardiographically analyzed. Plasma concentrations of Arg derivatives were measured by liquid chromatography tandem-mass spectrometry. In 143 (70%) patients suffering from DD, ADMA showed the strongest association with DD (0.66 ± 0.16, 0.72 ± 0.24, and 0.76 ± 0.26 µmol/L, p < 0.01 for trend). In linear regression analyses, positive association per standard deviation increase of ADMA was found with E-wave (beta coefficient (95% confidence interval): 4.72 (0.43–9.01); p < 0.05) and mean E/E’ (1.76 (0.73–2.79) p < 0.001). Associations were adjusted for age, sex, body mass index (BMI), diabetes mellitus, coronary artery disease, and arterial hypertension. Elevated ADMA is associated with the severity of DD in HCM. Higher ADMA level might lead to decreased NO production and thus an impaired myocardial relaxation pattern.

Association between asymmetric dimethylarginine serum levels and left ventricular longitudinal deformation in patients with normal ejection fractions: a two-dimensional speckle-tracking echocardiography examination

OBJECTIVES

Nitric oxide is an endogenous substance that preserves the myocardial function in patients with heart failure. Asymmetric dimethylarginine (ADMA) is a competitive inhibitor of endogenous nitric oxide synthase. We sought to explore the association between the left ventricular (LV) function as assessed with two-dimensional echocardiography and the serum level of ADMA in nondiabetic patients without significant coronary artery disease.

PATIENTS AND METHODS

Eighty-seven consecutive patients with normal LV ejection fractions were included in this cross-sectional study. The ADMA serum level was measured, and the longitudinal deformation indices of the LV myocardium were evaluated using two-dimensional speckle-tracking echocardiography (2DSTE).

RESULTS

The systolic strain, the systolic strain rate, and the early and late diastolic strain rates as evaluated with 2DSTE were not statistically significantly different between the patients with normal ADMA serum levels and those with increased ADMA serum levels. The two study groups were also not significantly different in terms of the systolic and diastolic myocardial velocities obtained with tissue Doppler.

CONCLUSION

Our findings showed no statistically significant correlations between the serum ADMA level and the 2DSTE-derived indices of the longitudinal deformation of the LV myocardium in our nondiabetic patients without significant coronary artery stenosis and with normal LV ejection fractions.

Metabolomic Approach to Redox and Nitrosative Reactions in Cardiovascular Diseases

Metabolomics, also referred to as metabonomics, is one of the most recent innovative technologies in medicine. It offers a direct functional read-out of phenotypes by the detection, identification, and quantification of a large number of metabolites within a biological sample such as urine and blood. Metabolites (<1500 Da) represent the output of cellular metabolism, accounting for expression and activity of genes, transcripts, and proteins, and offering unique insights into small molecule regulation, which may uncover new biochemical patterns. Metabolomics research has considerable potential for translating the metabolic fingerprint into personalized therapeutic strategies. Within the field of interest, cardiovascular disease (CVD) is one of the most developed areas. However, CVD remains the leading cause of death worldwide with a marked increase in mortality rates over the past six decades. In this scenario, recent findings indicate the important role of redox and nitrosative (RN) reactions in CVD development and progression. RN reactions are generally involved in the homeostatic modulation of a wide number of cellular and organ functions. Conversely, the imbalance of these reactions may lead to a condition of allostasis that in turn can cause CVD. The aim of this review is to highlight how the use of metabolomics may be useful for the study of RN reactions related to CVD, providing a tool to understand the mechanisms underlying reactions that could lead to impaired ROS or RNS formation.

Asymmetric dimethylarginine (ADMA) as an important risk factor for the increased cardiovascular diseases and heart failure in chronic kidney disease

Patients with chronic kidney disease have an increased cardiovascular morbidity and mortality. It has been recognized that the traditional cardiovascular risk factors could only partially explain the increased cardiovascular morbidity and mortality in patients with chronic kidney disease. Asymmetric dimethylarginine (ADMA) and N-monomethy l-arginine (L-NMMA) are endogenous inhibitors of nitric oxide synthases that attenuate nitric oxide production and enhance reactive oxidative specie generation. Increased plasma ADMA and/or L-NMMA are strong and independent risk factor for chronic kidney disease, and various cardiovascular diseases such as hypertension, coronary artery disease, atherosclerosis, diabetes, and heart failure. Both ADMA and L-NMMA are also eliminated from the body through either degradation by dimethylarginine dimethylaminohydrolase-1 (DDAH1) or urine excretion. This short review will exam the literature of ADMA and L-NMMA degradation and urine excretion, and the role of chronic kidney diseases in ADMA and L-NMMA accumulation and the increased cardiovascular disease risk. Based on all available data, it appears that the increased cardiovascular morbidity in chronic kidney disease may relate to the dramatic increase of systemic ADMA and L-NMMA after kidney failure.

Serum concentrations of asymmetric and symmetric dimethylarginine are associated with mortality in acute heart failure patients

BACKGROUND

Serum concentrations of asymmetric (ADMA) and symmetric (SDMA) dimethylarginine are established predictors of total and cardiovascular mortality. However, the predictive capacity of ADMA and SDMA for hospital and 3-months mortality of patients with acute heart failure (AHF) is unknown.

METHODS & RESULTS

Out of 152 included AHF patients, 79 (52%) were female, and the mean patient age was 75.2 ± 10.3 years. Hospital and three-month mortality rates were 14.5% and 27.4%, respectively. Serum ADMA and SDMA levels at admission, determined by reversed phase high performance liquid chromatography, were higher in patients having at least one of the three signs implying venous volume overload (enlarged liver, ascites, peripheral edema), a consequence of right-sided heart failure, compared to patients without those signs. Univariable logistic regression analyses revealed a significant positive association of ADMA and SDMA concentrations with hospital mortality [odds ratio (OR) and 95% confidence interval (CI) per standard deviation (SD) increase: 2.22 (1.37-3.79), p = 0.002, and 2.04 (1.34-3.18), p = 0.001, respectively], and 3-months mortality [2.06 (1.36-3.26), p = 0.001, and 2.52 (1.67-4.04), p < 0.001, respectively]. These associations remained significant after adjusting for age, sex, mean arterial pressure, low-density lipoprotein cholesterol, glomerular filtration rate, and N-terminal pro-brain natriuretic peptide.

CONCLUSIONS

We conclude that ADMA and SDMA concentrations are associated with hospital and 3-month mortality and are increased by venous volume overload in AHF patients.

Metabolic Biomarkers in Heart Failure

Metabolomics is the study of small, organic molecules within biochemical pathways. With advancement of technology, nuclear magnetic resonance, gas chromatography, and mass spectrometry have allowed for the discovery and analysis of large databases of metabolites implicated in heart failure. Metabolomics also explores the patient and environment interactions and unlocks the link between environmental exposures and the development of cardiovascular disease. Although a relatively new field, metabolomics is poised to become a clinically impactful field that develops novel biomarkers and explores new therapeutic interventions in heart failure.

Effects of Xin-Ji-Er-Kang on Anticardiovascular Remodeling in L-NAME Induced Hypertensive Mice and Its Potential Mechanisms

Background

Xin-Ji-Er-Kang (XJEK) shows protective effects on the myocardial ischemic diseases in our previous reports. We hypothesized that XJEK may exert preventing effects on L-NAME induced hypertensive mice by ameliorating oxidative stress (OS) and endothelial dysfunction (ED).

Methods

After treatment with XJEK for four weeks, cardiac function and cardiovascular pathology changes were evaluated. Then, endothelial-dependent vascular relaxation and serum NO, eNOS, AMDA, SOD, MDA content, and cardiac tissue eNOS expression were detected.

Results

The hypertensive mice displayed distinct cardiovascular remodeling including increased HW/BW index (4.7 ± 0.33 versus 5.2 ± 0.34), cross-section area, and collagen deposition. In addition, ED was found manifested by decreased serum NO (20.54 ± 8.05 versus 6.29 ± 2.33), eNOS (28.34 ± 2.36 versus 20.37 ± 2.30), content, and decreased eNOS expression in cardiac tissue and damaged endothelium-dependent diastolic function. Moreover, OS was detected confirmed by decreased SOD activity and increased MDA content in serum. However, treatment with XJEK for 4 wk could reverse cardiovascular remodeling (HW/BW index normalized from 5.2 ± 0.34 to 4.59 ± 0.25), ameliorate and preserve endothelial function (NO: 16.67 ± 7.24 versus 6.29 ± 2.33; eNOS: 16.67 ± 7.24 versus 6.29 ± 2.33), and suppress OS.

Conclusion

XJEK has protective effects against cardiovascular remodeling in L-NAME induced hypertensive mice.

Metabolomic analysis of oxidative stress: Superoxide dismutase mutation and paraquat induced stress in Drosophila melanogaster

Oxidative stress results in substantial biochemical and physiological perturbations in essentially all organisms. To determine the broad metabolic effects of oxidative stress, we have quantified the response in Drosophila melanogaster to both genetically and environmentally derived oxidative stress. Flies were challenged with loss of Superoxide dismutase activity or chronic or acute exposure to the oxidizing chemical paraquat. Metabolic changes were then quantified using a recently developed chemical isotope labeling (CIL) liquid chromatography - mass spectrometry (LC-MS) platform that targets the carboxylic acid and amine/phenol submetabolomes with high metabolic coverage. We discovered wide spread changes in both submetabolomes in response to all three types of stresses including: changes to the urea cycle, tryptophan metabolism, porphyrin metabolism, as well as a series of metabolic pathways involved in glutathione synthesis. Strikingly, while there are commonalities across the conditions, all three resulted in different metabolomic responses, with the greatest difference between the genetic and environmental responses. Genetic oxidative stress resulted in substantially more widespread effects, both in terms of the percent of the metabolome altered, and the magnitude of changes in individual metabolites. Chronic and acute environmental stress resulted in more similar responses although both were distinct from genetic stress. Overall, these results indicate that the metabolomic response to oxidative stress is complex, reaching across multiple metabolic pathways, with some shared features but with more features unique to different, specific stressors.

AGXT2 rs37369 polymorphism predicts the renal function in patients with chronic heart failure

Patients with chronic heart failure (CHF) are often accompanied with varying degrees of renal diseases. The purpose of this study was to identify rs37369 polymorphism of AGXT2 specific to the renal function of CHF patients. A total of 1012 southern Chinese participants, including 487 CHF patients without history of renal diseases and 525 healthy volunteers, were recruited for this study. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was used to determine the genotypes of AGXT2 rs37369 polymorphism. Levels of blood urea nitrogen (BUN) and serum creatinine (SCr) were detected to indicate the renal function of the participants. BUN level was significantly higher in CHF patients without history of renal diseases compared with healthy volunteers (p=0.000). And the similar result was also obtained for SCr (p=0.000). Besides, our results indicated that the level of BUN correlated significantly with SCr in both the CHF patients without renal diseases (r=0.4533, p<0.0001) and volunteers (r=0.2489, p<0.0001). Furthermore, we found that the AGXT2 rs37369 polymorphism could significantly affect the level of BUN in CHF patients without history of renal diseases (p=0.036, AA+AG vs GG). Patients with rs37369 GG genotype showed a significantly reduced level of BUN compared to those with the AA genotype (p=0.024), and the significant difference was still observed in the smokers of CHF patients without renal diseases (p=0.023). In conclusion, we found that CHF might induce the impairment of kidney and cause deterioration of renal function. AGXT2 rs37369 polymorphism might affect the renal function of CHF patients free from renal diseases, especially in patients with cigarette smoking.

Cardiomyocyte dimethylarginine dimethylaminohydrolase-1 (DDAH1) plays an important role in attenuating ventricular hypertrophy and dysfunction

Asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of nitric oxide synthases that limits nitric oxide bioavailability. Dimethylarginine dimethylaminohydrolase-1 (DDAH1) exerts a critical role for ADMA degradation and plays an important role in NO signaling. In the heart, DDAH1 is observed in endothelial cells and in the sarcolemma of cardiomyocytes. While NO signaling is important for cardiac adaptation to stress, DDAH1 impact on cardiomyocyte homeostasis is not clear. Here we used the MerCreMer-LoxP model to specifically disrupt cardiomyocyte DDAH1 expression in adult mice to determine the physiological impact of cardiomyocyte DDAH1 under basal conditions and during hypertrophic stress imposed by transverse aortic constriction (TAC). Under control conditions, cardiomyocyte-specific DDAH1 knockout (cDDAH KO) had no detectable effect on plasma ADMA and left ventricular (LV) hypertrophy or function in adult or aging mice. In response to TAC, DDAH1 levels were elevated 2.5-fold in WT mice, which exhibited no change in LV or plasma ADMA content and moderate LV hypertrophy and LV dysfunction. In contrast, cDDAH1 KO mice exposed to TAC showed no increase in LV DDAH1 expression, slightly increased LV tissue ADMA levels, no increase in plasma ADMA, but significantly exacerbated LV hypertrophy, fibrosis, nitrotyrosine production, and LV dysfunction. These findings indicate cardiomyocyte DDAH1 activity is dispensable for cardiac function under basal conditions, but plays an important role in attenuating cardiac hypertrophy and ventricular remodeling under stress conditions, possibly through locally confined regulation of subcellular ADMA and NO signaling.

High-density lipoprotein-associated paraoxonase-1 activity for prediction of adverse outcomes in outpatients with chronic heart failure

AIMS

Decreased arylesterase (ArylE) activity of paraoxonase-1, a HDL-associated protein with anti-inflammatory and antioxidant properties, has been associated with increased risk of cardiac events in patients with ischaemic heart failure (HF). We aim to investigate the prognostic significance of changes in serum ArylE activity over time.

METHODS AND RESULTS

We examined the association between baseline and follow-up serum ArylE activity and HF outcomes (death, cardiac transplantation, or ventricular assist device implantation) in 299 patients with HF enrolled in a prospective cohort study from January 2008 to July 2009, with 145 patients having available follow-up levels at 1 year. A significant drop in ArylE activity on follow-up was defined as a drop of ≥25% vs. baseline levels. Mean baseline and follow-up ArylE activity levels were 110.6 ± 29.9 µmol/min/mL and 106.2 ± 29.9 µmol/min/mL, respectively. After a mean follow-up of 2.8 ± 1.1 years, low baseline ArylE activity was associated with increased risk of adverse HF events [hazard ratio (HR; lowest vs highest tertile) 2.6, 95% confidence interval (CI) 1.3-5.5, P = 0.01] and HF-related hospitalization [incidence rate ratio (lowest vs. highest tertile) 2.1, 95% CI 1.2-4.1, P = 0.016], which remained significant after adjustment for age, male gender, systolic blood pressure, diabetes, creatinine clearance, CAD, and HDL-cholesterol levels. Patients who had a significant drop in ArylE activity on follow-up (n = 18) had a significantly increased risk of HF events (HR 4.9, 95% CI 1.6-14.6, P = 0.005), even after adjustment for baseline levels of ArylE activity.

CONCLUSIONS

Reduced baseline ArylE activity and decreased levels on follow-up are associated with adverse outcomes in stable outpatients with HF.

Asymmetric dimethylarginine and all-cause mortality: a systematic review and meta-analysis

Asymmetrical dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthase (NOS), impairs the beneficial effect of NO. The predictive value of ADMA for all-cause mortality remains controversial, though it is important in the development of cardiovascular disease (CVD) and progression to dialysis in renal disease. This systematic review and meta-analysis was conducted to investigate the association between circulating ADMA and all-cause mortality. Studies with data pertinent to the association between circulating ADMA and all-cause mortality were reviewed and OR, HR or RR with 95% CI derived from multivariate Cox's proportional-hazards analysis were extracted. A total of 34 studies reporting 39137 participants were included in final analysis. The results demonstrated that circulating ADMA was independently associated with all-cause mortality (RR = 1.27, 95% CI: 1.20-1.34). The association was still statistically significant in patients with pre-existing renal disease (RR = 1.30, 95% CI: 1.19-1.43) and pre-existing CVD (RR = 1.26, 95% CI: 1.16-1.37). In those without pre-existing renal or CVD, ADMA also predicted all-cause mortality (RR = 1.31, 95% CI: 1.13-1.53). The present study suggests a positive association of circulating ADMA with all-cause mortality. Further studies are needed to investigate the effects of interventions on ADMA, and the value of ADMA as a biomarker.

Toxic Dimethylarginines: Asymmetric Dimethylarginine (ADMA) and Symmetric Dimethylarginine (SDMA)

Asymmetric and symmetric dimethylarginine (ADMA and SDMA, respectively) are toxic, non-proteinogenic amino acids formed by post-translational modification and are uremic toxins that inhibit nitric oxide (NO) production and play multifunctional roles in many human diseases. Both ADMA and SDMA have emerged as strong predictors of cardiovascular events and death in a range of illnesses. Major progress has been made in research on ADMA-lowering therapies in animal studies; however, further studies are required to fill the translational gap between animal models and clinical trials in order to treat human diseases related to elevated ADMA/SDMA levels. Here, we review the reported impacts of ADMA and SDMA on human health and disease, focusing on the synthesis and metabolism of ADMA and SDMA; the pathophysiological roles of these dimethylarginines; clinical conditions and animal models associated with elevated ADMA and SDMA levels; and potential therapies against ADMA and SDMA. There is currently no specific pharmacological therapy for lowering the levels and counteracting the deleterious effects of ADMA and SDMA. A better understanding of the mechanisms underlying the impact of ADMA and SDMA on a wide range of human diseases is essential to the development of specific therapies against diseases related to ADMA and SDMA.

Increased Symmetric Dimethylarginine Level Is Associated with Worse Hospital Outcomes through Altered Left Ventricular Ejection Fraction in Patients with Acute Myocardial Infarction

Objectives

We aimed to investigate whether SDMA- symmetric dimethylarginine -the symmetrical stereoisomer of ADMA- might be a marker of left ventricular function in AMI.

Background

Asymmetric dimethylarginine (ADMA) has been implicated in the prognosis after acute myocardial infarction (AMI) and heart failure (HF).

Methods

Cross sectional prospective study from 487 consecutive patients hospitalized <24 hours after AMI. Patients with HF on admission were excluded. Serum levels of ADMA, SDMA and L-arginine were determined using HPLC. Glomerular filtration rate (eGFR) was estimated based on creatinine levels. Outcomes were in-hospital severe HF, as defined by Killip class >2, and death.

Results

Patients were analysed based on SDMA tertiles. Sex, diabetes, dyslipidemia, and prior MI were similar for all tertiles. In contrast, age and hypertension increased across the tertiles (p<0.001). From the first to the last tertile, GRACE risk score was elevated while LVEF and eGFR was reduced. The rate of severe HF and death were gradually increased across the SDMA tertiles (from 0.6% to 7.4%, p = 0.006 and from 0.6% to 5.0%, p = 0.034, respectively). Backward logistic multivariate analysis showed that SDMA was an independent estimate of developing severe HF, even when adjusted for confounding (OR(95%CI): 8.2(3.0–22.5), p<0.001). Further, SDMA was associated with mortality, even after adjustment for GRACE risk score (OR(95%CI): 4.56(1.34–15.52), p = 0.015).

Conclusions

Our study showed for the first time that SDMA is associated with hospital outcomes, through altered LVEF and may have biological activity beyond renal function.

Asymmetric and Symmetric Dimethylarginine as Risk Markers for Total Mortality and Cardiovascular Outcomes: A Systematic Review and Meta-Analysis of Prospective Studies

Background

A growing number of studies linked elevated concentrations of circulating asymmetric (ADMA) and symmetric (SDMA) dimethylarginine to mortality and cardiovascular disease (CVD) events. To summarize the evidence, we conducted a systematic review and quantified associations of ADMA and SDMA with the risks of all-cause mortality and incident CVD in meta-analyses accounting for different populations and methodological approaches of the studies.

Methods

Relevant studies were identified in PubMed until February 2015. We used random effect models to obtain summary relative risks (RR) and 95% confidence intervals (95%CIs), comparing top versus bottom tertiles. Dose-response relations were assessed by restricted cubic spline regression models and potential non-linearity was evaluated using a likelihood ratio test. Heterogeneity between subgroups was assessed by meta-regression analysis.

Results

For ADMA, 34 studies (total n = 32,428) investigating associations with all-cause mortality (events = 5,035) and 30 studies (total n = 30,624) investigating the association with incident CVD (events = 3,396) were included. The summary RRs (95%CI) for all-cause mortality were 1.52 (1.37–1.68) and for CVD 1.33 (1.22–1.45), comparing high versus low ADMA concentrations. Slight differences were observed across study populations and methodological approaches, with the strongest association of ADMA being reported with all-cause mortality in critically ill patients. For SDMA, 17 studies (total n = 18,163) were included for all-cause mortality (events = 2,903), and 13 studies (total n = 16,807) for CVD (events = 1,534). High vs. low levels of SDMA, were associated with increased risk of all-cause mortality [summary RR (95%CI): 1.31 (1.18–1.46)] and CVD [summary RR (95%CI): 1.36 (1.10–1.68) Strongest associations were observed in general population samples.

Conclusions

The dimethylarginines ADMA and SDMA are independent risk markers for all-cause mortality and CVD across different populations and methodological approaches.

Pharmacological inhibition of arginine and lysine methyltransferases induces nuclear abnormalities and suppresses angiogenesis in human endothelial cells

Posttranslational modifications of histone tails can alter chromatin structure and regulate gene transcription. While recent studies implicate the lysine/arginine protein methyltransferases in the regulation of genes for endothelial metabolism, the role of AMI-1 and AMI-5 compounds in angiogenesis remains unknown. Here, we show that global inhibition of arginine and lysine histone methyltransferases (HMTs) by AMI-5 induced an angiostatic profile in human microvascular endothelial cells and human umbilical vein endothelial cells. Based on FACS analysis, we found that inhibition of HMTs significantly affects proliferation of endothelial cells, by suppressing cell cycle progression in the G₀/G₁ phase. Immunofluorescent studies of the endothelial cells replication pattern by 5-ethynyl-2'-deoxyuridine incorporation disclosed that AMI-5, and the arginine methyltransferase inhibitor AMI-1, induced heterochromatin formation and a number of nuclear abnormalities, such as formation of micronuclei (MNs) and nucleoplasmic bridges (NPBs), which are markers of chromosomal instability. In addition to the modification of the cell cycle machinery in response to AMIs treatment, also endothelial cells migration and capillary-like tube formation processes were significantly inhibited, implicating a stimulatory role of HMTs in angiogenesis.

Physiological Techniques and Pulmonary Hypertension - Left Heart Disease

Group 2 Pulmonary hypertension (PH) is associated with left heart disease (LHD;Group 2 PH) and is the most common form of PH. Group 2 PH represents an important subgroup of patients with LHD where the development of PH leads to a significant increase in morbidity and mortality. Early diagnosis may provide an opportunity to intervene and significantly delay progression. In addition to clinical suspicion, several approaches including hemodynamic assessment, exercise testing, and imaging techniques play an important role in better disease characterization and management. Here, we review the role of physiologic based hemodynamic and exercise assessments of Group 2 PH patients.

In vivo microvascular and macrovascular endothelial function is not associated with circulating dimethylarginines in patients with rheumatoid arthritis: a prospective analysis of the DRACCO cohort

OBJECTIVES

To examine associations between asymmetric (ADMA), symmetric dimethylarginine (SDMA) and ADMA:SDMA ratio with assessments of endothelial function and coronary artery perfusion in RA patients.

METHODS

ADMA and SDMA levels were measured in 197 RA individuals [144 (77.4%) females, median age: 66 years (quartiles: 59-73)]. Patients underwent assessments of microvascular endothelium-dependent and endothelium-independent function, macrovascular endothelium-dependent and endothelium-independent function and vascular morphology (pulse wave analysis, carotid intima-media thickness (cIMT), and carotid plaque). Coronary perfusion was assessed by subendocardial viability ratio (SEVR).

RESULTS

SEVR correlated with SDMA (r = 0.172, p = 0.026) and ADMA:SDMA (r = -0.160, p = 0.041) in univariable analysis, but not in multivariable analysis accounting for confounding factors. Neither ADMA:SDMA ratio nor SDMA were significantly correlated with microvascular or macrovascular endothelial function, or with arterial stiffness and cIMT. Within subgroup of patients (n = 26) with high inflammatory markers, a post-hoc analysis showed that SDMA and the ADMA:SDMA ratio were significantly associated with endothelium-dependent microvascular function in univariable analysis, with Pearson's r correlation coefficients of -0.440 (p = 0.031) and 0.511 (p = 0.011), respectively. Similar finding were established between ADMA:SDMA ratio and arterial stiffness in univariable analysis, with Pearson's r of 0.493, (p = 0.024).

CONCLUSION

Dimethylarginines were not found to be significantly associated with several assessments of vascular function and morphology in patients with RA, however, post-hoc analysis indicates that there may be associations in patients with raised inflammatory markers. Our results suggest that dysregulated NO metabolism may not be the sole mechanism for the development of preclinical atherosclerosis in RA.

Effect of asymmetric dimethylarginine (ADMA) on heart failure development

Asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of nitric oxide synthases that limits nitric oxide bioavailability and can increase production of NOS derived reactive oxidative species. Increased plasma ADMA is a one of the strongest predictors of mortality in patients who have had a myocardial infarction or suffer from chronic left heart failure, and is also an independent risk factor for several other conditions that contribute to heart failure development, including hypertension, coronary artery disease/atherosclerosis, diabetes, and renal dysfunction. The enzyme responsible for ADMA degradation is dimethylarginine dimethylaminohydrolase-1 (DDAH1). DDAH1 plays an important role in maintaining nitric oxide bioavailability and preserving cardiovascular function in the failing heart. Here, we examine mechanisms of abnormal NO production in heart failure, with particular focus on the role of ADMA and DDAH1.

Elevated Plasma Marinobufagenin, An Endogenous Cardiotonic Steroid, Is Associated With Right Ventricular Dysfunction and Nitrative Stress in Heart Failure

BACKGROUND

Plasma levels of cardiotonic steroids are elevated in volume-expanded states, such as chronic kidney disease, but the role of these natriuretic hormones in subjects with heart failure (HF) is unclear. We sought to determine the prognostic role of the cardiotonic steroids marinobufagenin (MBG) in HF, particularly in relation to long-term outcomes.

METHODS AND RESULTS

We first measured plasma MBG levels and performed comprehensive clinical, laboratory, and echocardiographic assessment in 245 patients with HF. All-cause mortality, cardiac transplantation, and HF hospitalization were tracked for 5 years. In our study cohort, median (interquartile range) MBG was 583 (383-812) pM. Higher MBG was associated with higher myeloperoxidase (r=0.42, P<0.0001), B-type natriuretic peptide (r=0.25, P=0.001), and asymmetrical dimethylarginine (r=0.32, P<0.001). Elevated levels of MBG were associated with measures of worse right ventricular function (RV s', r=-0.39, P<0.0001) and predicted increased risk of adverse clinical outcomes (MBG≥574 pmol/L: hazard ratio 1.58 [1.10-2.31], P=0.014) even after adjustment for age, sex, diabetes mellitus, and ischemic pathogenesis. In mice, a left anterior descending coronary artery ligation model of HF lead to increases in MBG, whereas infusion of MBG into mice for 4 weeks lead to significant increases in myeloperoxidase, asymmetrical dimethylarginine, and cardiac fibrosis.

CONCLUSIONS

In the setting of HF, elevated plasma levels of MBG are associated with right ventricular dysfunction and predict worse long-term clinical outcomes in multivariable models adjusting for established clinical and biochemical risk factors. Infusion of MBG seems to directly contribute to increased nitrative stress and cardiac fibrosis.

Atrial Fibrillation Is Associated with a Marker of Endothelial Function and Oxidative Stress in Patients with Acute Myocardial Infarction

Background

Atrial fibrillation (AF), whether silent or symptomatic, is a frequent and severe complication of acute myocardial infarction (AMI). Asymmetric dimethylarginine (ADMA), an endogenous eNOS inhibitor, is a risk factor for endothelial dysfunction. We addressed the relationship between ADMA plasma levels and AF occurrence in AMI.

Methods

273 patients hospitalized for AMI were included. Continuous electrocardiographic monitoring (CEM) ≥48 hours was recorded and ADMA was measured by High Performance Liquid Chromatography on admission blood sample.

Results

The incidence of silent and symptomatic AF was 39(14%) and 29 (11%), respectively. AF patients were markedly older than patients without AF (≈ 20 y). There was a trend towards higher ADMA levels in patients with symptomatic AF than in patients with silent AF or no AF (0.53 vs 0.49 and 0.49 μmol/L, respectively, p = 0.18,). After matching on age, we found that patients with symptomatic AF had a higher heart rate on admission and a higher rate of patients with LV dysfunction (28% vs. 3%, p = 0.025). Patients who developed symptomatic AF had a higher ADMA level than patients without AF (0.53 vs. 0.43 μmol/L; p = 0.001). Multivariate logistic regression analysis to estimate symptomatic AF occurrence showed that ADMA was independently associated with symptomatic AF (OR: 2.46 [1.21–5.00], p = 0.013) beyond history of AF, LVEF<40% and elevated HR.

Conclusion

We show that high ADMA level is associated with the occurrence of AF. Although no causative role can be concluded from our observational study, our work further supports the hypothesis that endothelial dysfunction is involved in the pathogenesis of AF in AMI.

Intestinal microbiota-dependent phosphatidylcholine metabolites, diastolic dysfunction, and adverse clinical outcomes in chronic systolic heart failure

BACKGROUND

Trimethylamine-N-oxide (TMAO) has been linked to increased cardiovascular risk. We aimed to determine the prognostic value of TMAO and its dietary precursors, choline and betaine, in heart failure (HF).

METHODS AND RESULTS

In 112 patients with chronic systolic HF with comprehensive echocardiographic evaluation, we measured plasma TMAO, choline, and betaine by mass spectrometry. Median (interquartile range) TMAO levels, choline, and betaine levels were 5.8 (3.6-12.1) μmol/L, 10.9 (8.4-14.0) μmol/L, and 43.8 (37.1-53.0) μmol/L, respectively, and were correlated with each other (all P < .0001 for both). TMAO levels were significantly higher in patients with diabetes mellitus (9.4 [4.9-13.2] vs 4.8 [3.4-9.8] μmol/L; P = .005) and in subjects with New York Heart Association functional class III or greater (7.0 [4.7-14.8] vs 4.7 [3.4-11.3] μmol/L; P = .02). Elevated TMAO, choline, and betaine levels were each associated with higher plasma N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels and more advanced left ventricular diastolic dysfunction, but not systolic dysfunction or inflammatory and endothelial biomarkers. Higher choline (hazard ratio [HR] 1.64, 95% CI 1.22-2.20; P = .001), betaine (HR 1.51, 95% CI 1.10-2.08; P = .01), and TMAO (HR 1.48, 95% CI 1.10-1.96; P = .01) predicted increased risk for 5-year adverse clinical events (death/transplantation). Only higher TMAO levels predicted incident adverse clinical events independently from age, estimated glomerular filtration rate, mitral E/septal Ea, and NT-proBNP levels (HR 1.46, 95% CI 1.03-2.14; P = .03).

CONCLUSION

Elevated plasma TMAO, choline, and betaine levels are each associated with more advanced left ventricular diastolic dysfunction and portend poorer long-term adverse clinical outcomes in chronic systolic HF. However, only higher plasma TMAO was associated with poor prognosis after adjustment for cardiorenal indices.

Missense variants of the alanine:glyoxylate aminotransferase 2 gene are not associated with Japanese schizophrenia patients

Alanine:glyoxylate aminotransferase 2 (AGXT2) is the only enzyme that degrades D-3-aminoisobutyrate (D-AIB), which is an intermediate product of thymine, and 30-40% of Japanese lack AGXT2 activity genetically and excrete high amounts of D-AIB in their urine. Recently, AGXT2 is reported to metabolize asymmetric dimethyl arginine (ADMA), a competitive inhibitor of nitric oxide (NO) synthase. Since AGXT2 is expressed in the central nervous system, the loss of AGXT2 activity will be related to the vulnerability for neuropsychiatric disorders related to the NO system. In this study, we recruited 85 Japanese subjects to discover loss variants of the AGXT2 gene with the amount of D-AIB excretion in their urine. From the statistical relevance between them, we found three missense polymorphisms (rs37370, rs37369, and rs180749) independently related to AGXT2 activity (P<0.0001). Then, we performed a case-control association analysis of its missense polymorphisms with 1136 schizophrenia and 1908 control subjects because the NO system may be involved in the vulnerability of schizophrenia processes. We could not find any associations of three functional SNPs with schizophrenia pathogenesis in the analyses of either genotypic or allelic models. We concluded that the AGXT2 gene is not associated with schizophrenia in Japanese subjects.