High-throughput quantification of circulating metabolites improves prediction of subclinical atherosclerosis

Cross-sectional metabolic profiles of mental health in population-based cohorts of 11- to 12-year-olds and mid-life adults: The Longitudinal Study of Australian Children

OBJECTIVE

Poorer mental health in adulthood is associated with increased risk of cardiovascular disease and reduced life expectancy. However, little is known of the molecular pathways underpinning this relationship and how early in life adverse metabolite profiles relate to self-reported variation in mental health. We examined cross-sectional associations between mental health and serum metabolites indicative of cardiovascular health, in large Australian population-based cohorts at two stages of the life-course.

METHODS

We characterised cross-sectional serum nuclear magnetic resonance metabolite profiles of positively and negatively framed mental health in a large population-based sample of Australian 11- to 12-year-olds (n = 1172; 51% girls) and mid-life adults (n = 1322; mean age 45 years; 87% women). We examined multiple standard self-report mental health scales, spanning psychosocial health, general well-being, life satisfaction, and health-related quality of life. Linear regression was used to investigate the cross-sectional association between mental health and each metabolite (n = 73) in children and adults separately, unadjusted and adjusted for age, sex, socioeconomic position and body mass index.

RESULTS

Better child and adult mental health were associated with lower levels of the inflammatory marker glycoprotein acetyls, and a favourable, less atherogenic lipid/lipoprotein profile. Patterns of association in children were generally weaker than in adults. Associations were generally modest and partially attenuated when adjusted for body mass index.

CONCLUSIONS

In general, metabolite profiles associated with better child and adult mental health closely aligned with those predictive of better cardiovascular health in adults. Our findings support previous evidence for the likely bidirectional relationship between mental health and cardiovascular disease risk, by extending this evidence base to the molecular level and in children.

Consensus document of an expert group from the Spanish Society of Arteriosclerosis (SEA) on the clinical use of nuclear magnetic resonance to assess lipoprotein metabolism (Liposcale®)

The assessment and prevention of cardiovascular risk (CVR) that persists in patients with dyslipidaemia despite treatment and achievement of goals specific to the plasma concentration of cholesterol linked to low density (c-LDL) is a clinical challenge today, and suggests that conventional lipid biomarkers are insufficient for an accurate assessment of CVR. Apart from their lipid content, there are other lipid particle characteristics. The results of this study show that there are a number of lipoprotein compounds that determine atherogenic potential and its influence on the CVR. However, such additional characteristics cannot be analysed by the techniques commonly used in clinical laboratories. Nuclear Magnetic Resonance (NMR) is a technique that allows a detailed analysis to be made of the amount, composition, and size of lipoproteins, as well as providing more information about the detailed status of lipid metabolism and CVR in dyslipidaemia patients. In this article a group of lipidologists from the Spanish Society of Arteriosclerosis review the existing evidence on the atherogenic mechanisms of particles and describe the technical basis and interpretation of the profiles lipoproteins obtained by MRI, with special reference to the test available in Spain (Liposcale®). Likewise, the main patient profiles are defined as such that an analysis would provide information of greater clinical interest. These include: a) Suspected mismatch between lipid concentrations and particles, a common situation in diabetes, obesity, metabolic syndrome; b) Early atherothrombotic cardiovascular disease (ECVA) or recurrent without CVR factors to justify it; c) Lipid disorders, rare or complex, such as extreme concentrations of c-HDL, and d) Clinical situations where classical analytical techniques cannot be applied, such as very low c-LDL values.

Associations between serum metabolites and subclinical atherosclerosis in a Chinese population: the Taizhou Imaging Study

Metabolomics provides a promising tool for understanding the pathophysiology and identifying biomarkers of atherosclerosis. We aimed to estimate the associations between circulating metabolites and subclinical atherosclerosis in a Chinese cohort. The baseline serum levels of 38 metabolites of 489 individuals were measured using nuclear magnetic resonance. Associations between metabolites and brachial-ankle pulse wave velocity (baPWV) and carotid intima-media thickness (IMT) were determined using a linear regression. A multivariate logistic regression was used to evaluate the associations of metabolites and subclinical atherosclerosis defined as high baPWV (>median) and increased IMT (>median). After adjusting for covariates and multiple testing corrections (false discovery rate; FDR), two branched-chain amino acids (BCAAs; leucine and isoleucine), one ketone (acetoacetate), and two lipids were positively associated with baPWV. Lactate was inversely associated with IMT. Elevated acetoacetate levels (odds ratio: 1.53, 95% confidence interval: 1.20-1.97; FDR <0.001) and four other lipid features were associated with an increased risk of high baPWV. Alterations in circulating lipids and BCAAs were associated with the risk of arterial stiffness in the middle-aged Chinese population. Our findings provide clues to understanding the potential mechanisms of subclinical atherosclerosis; however, further validation in a broader population context and the exploration of potential clinical applications are warranted.

Central systolic pressure and a nonessential amino acid metabolomics profile: the African Prospective study on the Early Detection and Identification of Cardiovascular disease and Hypertension

OBJECTIVES

Early-life exposures to cardiovascular risk factors may manifest as early vascular ageing, a phenomenon to which black populations are more prone. The metabolome provides insight into the current state and regulation of physiological processes and was used to investigate the early molecular determinants of arterial stiffness.

METHODS

Black (N = 80) and white (N = 80) men and women (aged 20-30 years, clinic blood pressure <140 and 90 mmHg) across the arterial stiffness spectrum were included. Carotid-femoral pulse wave velocity, central SBP (cSBP) and central pulse pressure (cPP) were measured. NMR spectroscopy, liquid chromatography tandem mass spectrometry and gas chromatography-time of flight-mass spectrometry methods produced metabolomic data.

RESULTS

Differences (d ≥ 0.3) in 34 metabolites between black and white groups were found (adjusted for multiple comparisons). Only cSBP were higher in the black group (P = 0.003). Lower dietary protein intake (P < 0.001), but higher urinary nonessential amino acid levels were found in the black group (q ≤ 0.05). In multivariable-adjusted regression models cSBP and cPP inversely correlated with various nonessential amino acids, but only in black adults. These include associations of cSBP with 4-hydroxyproline (β = -0.24; P = 0.042), alanine: (β = -0.29; P = 0.015), glutamine (β = -0.25; P = 0.028), glycine (β = -0.26; P = 0.027), histidine (β = -0.30; P = 0.009), serine (β = -0.29; P = 0.012), and associations of cPP with alanine (β = -0.31; P = 0.005) and serine (β = -0.26; P = 0.019).

CONCLUSION

These amino acids play pivotal roles in collagen metabolism, glucose metabolism and oxidative stress and this ethnic-specific finding suggests that biosynthesis of nonessential amino acids may be upregulated to protect the vasculature against the onset of early vascular deterioration.

Precipitated sdLDL: An easy method to estimate LDL particle size

Background

LDL‐C lowering is the main measure in cardiovascular disease prevention but a residual risk of ischemic events still remains. Alterations of lipoproteins, specially, increase in small dense LDL (sdLDL) particles are related to this risk.

Objective

To investigate the potential use of sdLDL cholesterol concentration (sdLDL‐C) isolated by an easy precipitation method and to assess the impact of a set of clinical and biochemical variables determined by NMR on sdLDL concentration.

Methods

sdLDL‐C and NMR lipid profile were performed in 85 men samples. Association among them was evaluated using Pearson coefficients (r_xy). A multivariate regression was performed to identify the influence of NMR variables on sdLDL‐C.

Results

A strong association between sdLDL‐C and LDLLDL‐P (r_xy = 0.687) and with LDL‐Z (r_xy = −0.603) was found. The multivariate regression explained a 56.8% in sdLDL‐C variation (P = 8.77.10‐12). BMI, ApoB, triglycerides, FFA, and LDL‐Z showed a significant contribution. The most important ones were ApoB and LDL‐Z; a 1nm increase (LDL‐Z) leads to decrease 126 nmol/L in sdLDL‐C.

Conclusion

The association between sdLDL‐C, LDL‐Z, and LDL‐P is clear. From a large number of variables, especially LDL‐Z and apoB influence on sdLDL‐C. Results show that the smaller the LDL size, the higher their cholesterol concentration. Therefore, sdLDL‐C determination by using this easy method would be useful to risk stratification and to uncover cardiovascular residual risk.

A detailed lipoprotein profile in relation to intima-media thickness and echogenicity of three major arteries

OBJECTIVE

To investigate differences in risk-factor profile, with special emphasis on detailed characterization of the lipoprotein profile, for intima-media thickness (IMT) and echogenicity of the intima-media complex (IM-GSM) in three major arteries: the carotid, femoral and brachial arteries.

METHODS

IMT and IM-GSM were measured by ultrasound in the carotid, femoral and brachial arteries in 778 subjects, all aged 75 years (50% women), in the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study, in which a detailed lipoprotein profile was also determined by nuclear magnetic resonance spectroscopy.

RESULTS

First, IMT was considerably lower, and IM-GSM higher, in the brachial artery compared to the other two arteries. Second, IMT and IM-GSM in the arteries were related to each other. Third, significant different traditional risk-factor profiles were seen for both IMT and IM-GSM, with generally weaker relationships for IMT in the femoral and brachial arteries compared with the carotid artery. Fourth, the strength of associations between an atherogenic lipoprotein profile and IMT in the carotid artery was attenuated in the femoral artery and virtually absent in the brachial artery. Fifth, slightly different lipoprotein profiles were seen for IM-GSM in the three arteries.

CONCLUSION

Differences between the carotid, femoral and brachial artery IMT and IM-GSM were seen regarding the traditional risk factors, as well as the lipoprotein profile.

Atherosclerotic metabolites: basic science is progressing, so we need to think about clinical implications

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Serum metabolic signatures of coronary and carotid atherosclerosis and subsequent cardiovascular disease

AIMS

To characterize serum metabolic signatures associated with atherosclerosis in the coronary or carotid arteries and subsequently their association with incident cardiovascular disease (CVD).

METHODS AND RESULTS

We used untargeted one-dimensional (1D) serum metabolic profiling by proton nuclear magnetic resonance spectroscopy (1H NMR) among 3867 participants from the Multi-Ethnic Study of Atherosclerosis (MESA), with replication among 3569 participants from the Rotterdam and LOLIPOP studies. Atherosclerosis was assessed by coronary artery calcium (CAC) and carotid intima-media thickness (IMT). We used multivariable linear regression to evaluate associations between NMR features and atherosclerosis accounting for multiplicity of comparisons. We then examined associations between metabolites associated with atherosclerosis and incident CVD available in MESA and Rotterdam and explored molecular networks through bioinformatics analyses. Overall, 30 1H NMR measured metabolites were associated with CAC and/or IMT, P = 1.3 × 10-14 to 1.0 × 10-6 (discovery) and P = 5.6 × 10-10 to 1.1 × 10-2 (replication). These associations were substantially attenuated after adjustment for conventional cardiovascular risk factors. Metabolites associated with atherosclerosis revealed disturbances in lipid and carbohydrate metabolism, branched chain, and aromatic amino acid metabolism, as well as oxidative stress and inflammatory pathways. Analyses of incident CVD events showed inverse associations with creatine, creatinine, and phenylalanine, and direct associations with mannose, acetaminophen-glucuronide, and lactate as well as apolipoprotein B (P < 0.05).

CONCLUSION

Metabolites associated with atherosclerosis were largely consistent between the two vascular beds (coronary and carotid arteries) and predominantly tag pathways that overlap with the known cardiovascular risk factors. We present an integrated systems network that highlights a series of inter-connected pathways underlying atherosclerosis.

Application of Metabolomics to Epidemiological Studies of Atherosclerosis and Cardiovascular Disease

Metabolomics has developed as a powerful tool for investigating the complex pathophysiology underlying atherosclerosis and cardiovascular disease. Many epidemiological studies have applied this technique to accurately and comprehensively assess the effects of environmental factors on health outcomes, which used to be a perpetual challenge. Metabolites are defined as small molecules which are intermediate products of metabolic reactions catalyzed by numerous enzymes occurring within cells. Consequent to both genetic variation and environment, they allow us to explore the gene–environment interactions and to gain a better understanding of multifactorial diseases like cardiovascular disease. This review article highlights the findings of well-known prospective cohort studies around the world that have utilized metabolomics for a wide range of purposes, including biomarker discovery, improving cardiovascular risk prediction and early disease diagnosis, and exploring detailed mechanisms of disease onset and progression. However, technical challenges still exist in applying them clinically. One limitation is due to various analytical platforms that are used based on the judgment of each study; comparative assessments among different platforms need to be conducted in order to correctly interpret and validate each data externally. Secondly, metabolite levels obtained in most high-throughput metabolomics profiling studies are often semiquantitative rather than fully quantitative concentrations, which makes it difficult to compare and combine results among different studies and to determine the levels for practical use. In 2014, the Consortium of Metabolomics Studies was developed, which is expected to take the lead in overcoming these issues.

A Cross-Cohort Study Examining the Associations of Metabolomic Profile and Subclinical Atherosclerosis in Children and Their Parents: The Child Health CheckPoint Study and Avon Longitudinal Study of Parents and Children

Background High-throughput nuclear magnetic resonance profiling of circulating metabolites is suggested as an adjunct for cardiovascular risk evaluation. The relationship between metabolites and subclinical atherosclerosis remains unclear, particularly among children. Therefore, we examined the associations of metabolites with carotid intima-media thickness ( cIMT ) and arterial pulse wave velocity ( PWV ). Methods and Results Data from two independent population-based studies was examined; (1) cross-sectional associations with cIMT and PWV in 1178 children (age 11-12 years, 51% female) and 1316 parents (mean age 45 years, 87% female) from the CheckPoint study (Australia); and (2) longitudinal associations in 4249 children (metabolites at 7-8 years, PWV at 10-11 years, 52% female), and cross-sectional associations in 4171 of their mothers (mean age 48 years, cIMT data) from ALSPAC (The Avon Longitudinal Study of Parents and Children; UK ). Metabolites were measured by the same nuclear magnetic resonance platform in both studies, comprising of 69 biomarkers. Biophysical assessments included body mass index, blood pressure, cIMT and PWV . In linear regression analyses adjusted for age, sex, body mass index, and blood pressure, there was no evidence of metabolite associations in either children or adults for cIMT at a 10% false discovery threshold. In CheckPoint adults, glucose was positively, and some high-density lipoprotein-cholesterol derived measures and amino acids (glutamine, histidine, tyrosine) inversely associated with PWV. Conclusions These data suggest that in children circulating metabolites have no consistent association with cIMT and PWV once adjusted for body mass index and blood pressure. In their middle-aged parents, some evidence of metabolite associations with PWV were identified that warrant further investigation.

Metabolomics study in severe extracranial carotid artery stenosis

BACKGROUND

Significant genetic association has been found in patients with severe carotid artery stenosis (CAS). The present study wished to investigate if metabolites may also act as biomarkers for CAS.

METHODS

Consecutive patients with at least one carotid artery stenosis > = 60% on cerebral angiography were prospectively recruited from May 2007 to January 2016. Normal controls were recruited from outpatient clinic who had no stroke and coronary artery disease (CAD) history, and the brain magnetic resonance or computed tomographic angiography showed bilateral CAS < 30%. Risk factor profile, clinical characteristics, age, and clinical features were recorded. All subjects were male, and none had diabetes. ¹H-NMR spectroscopy-based metabolomics analysis was carried out for plasma samples.

RESULTS

Totally, 130 male subjects were recruited. Age had no significant difference between the controls and CAS group (60.2 ± 5.9 vs. 63.3 ± 6.0, p = 0.050). The CAS group had significantly higher frequency of CAD, hypertension, smoking and alcohol but lower body mass index than the controls (p < 0.05). The laboratory tests showed CAS group had significantly higher level of homocysteine but lower levels of cholesterol, high-density lipoprotein and hemoglobin than the controls (p < 0.05). The ¹H-NMR based plasma metabolomics analysis indicated that choline was significantly lower in CAS patients. The VIP values of lipids were greater than 1.0, which were considered significantly different.

CONCLUSIONS

Our results suggest homocysteine, choline and lipids in association with traditional risk factors may be involved in the pathogenesis of CAS. Diet adjustment to control homocysteine, choline and lipids may be helpful for the prevention of CAS.

Sex and puberty-related differences in metabolomic profiles associated with adiposity measures in youth with obesity

BACKGROUND

Specific patterns of metabolomic profiles relating to cardiometabolic disease are associated with increased weight in adults. In youth with obesity, metabolomic data are sparse and associations with adiposity measures unknown.

OBJECTIVES

Primary, to determine associations between adiposity measures and metabolomic profiles with increased cardiometabolic risks in youth with obesity. Secondary, to stratify associations by sex and puberty.

METHODS

Participants were from COBRA (Childhood Overweight BioRepository of Australia; a paediatric cohort with obesity). Adiposity measures (BMI, BMI z-score, %truncal and %whole body fat, waist circumference and waist/height ratio), puberty staging and NMR metabolomic profiles from serum were assessed. Statistics included multivariate analysis (principal component analysis, PCA) and multiple linear regression models with false discovery rate adjustment.

RESULTS

214 participants had metabolomic profiles analyzed, mean age 11.9 years (SD ± 3.1), mean BMI z-score 2.49 (SD ± 0.24), 53% females. Unsupervised PCA identified no separable clusters of individuals. Positive associations included BMI z-score and phenylalanine, total body fat % and lipids in medium HDL, and waist circumference and tyrosine; negative associations included total body fat % and the ratio of docosahexaenoic acid/total fatty acids and histidine. Stratifying by sex and puberty, patterns of associations with BMI z-score in post-pubertal males included positive associations with lipid-, cholesterol- and triglyceride-content in VLDL lipoproteins; total fatty acids; total triglycerides; isoleucine, leucine and glycoprotein acetyls.

CONCLUSION

In a paediatric cohort with obesity, increased adiposity measures, especially in post-pubertal males, were associated with distinct patterns in metabolomic profiles.

Ambient fine particulate matter exposure induces cardiac functional injury and metabolite alterations in middle-aged female mice

Plenty of epidemiological studies have shown that exposure to ambient particulate matter (PM_2.5) is linked to cardiovascular diseases (CVDs) in older even in middle-aged populations; however, experimental evidence through intuitive metabolic analysis to confirm the age susceptibility and explain the related molecular mechanism of PM_2.5-induced cardiotoxicity is relatively rare. In the present study, C57BL/6 mice (adult (4-month) and middle-aged (10-month)) were given 3 mg/kg PM_2.5 every other day by oropharyngeal aspiration for 4 weeks, and then, body and cardiac parameter, containing weight data, cardiac function, ultrastructure, metabolic analysis, and molecular detection were conducted to investigate the PM_2.5-induced cardiotoxicity. The results indicated that middle-aged mice were more susceptible to PM_2.5, displaying slow cardiac growth, cardiac dysfunction, abnormal mitochondrial structure and function, and cardiac metabolic disorders. The altered metabolites were enriched in carbohydrate metabolism, fatty acid metabolism, amino acid metabolism, nucleotide metabolism and nicotinate and nicotinamide metabolism. In conclusion, we speculated that the cardiac metabolic disorders may be important factors in PM_2.5-induced cardiac dysfunction and mitochondrial structure destruction in middle-aged mice, providing a new direction for the study of the association between PM_2.5 and CVDs.

Interaction of clopidogrel and fufang danshen dripping pills assay in coronary heart disease based on non-target metabolomics

ETHNOPHARMACOLOGICAL RELEVANCE

Clopidogrel is the recommended treatment by current clinical practice guidelines to prevent adverse cardiovascular events in patients with coronary heart disease (CHD), but this treatment regimen still fails and 5-40% patients display inadequate antiplatelet responses. Fufang Danshen Dripping Pill (FDDP), a Chinese patient drug, was used as the combination with clopidogrel to improve the therapeutic effect. However, the mechanism of the interaction between clopidogrel and FDDP has not been elucidated.

MATERIALS AND METHODS

We have used non-targeted metabolism method based on GC-MS and LC-MS for the investigation of drug interactions between clopidogrel and FDDP. 63 patients were divided into four groups with different dosage regimen and the serum samples were collected for the analysis.

RESULTS

We have found 5 and 55 differential metabolites between health volunteer group and CHD patients group, respectively. The contents of these differential metabolites had diverse changes in clopidogrel group, FDDP group, and drug combination group, indicating that the clopidogrel and FDDP combination can adjust the glycometabolism, lipid metabolism, and phospholipid metabolism, sequentially made the content of downstream related metabolites towards to the health volunteer group.

CONCLUSION

This work has explained the mechanism of the interaction between clopidogrel and FDDP from the point of view of metabolic product change, and revealed the potential metabolic pathways it affects, which provided the new ideas for clinical medication.

Specific Amino Acids Affect Cardiovascular Diseases and Atherogenesis via Protection against Macrophage Foam Cell Formation: Review Article

The strong relationship between cardiovascular diseases (CVD), atherosclerosis, and endogenous or exogenous lipids has been recognized for decades, underestimating the contribution of other dietary components, such as amino acids, to the initiation of the underlying inflammatory disease. Recently, specific amino acids have been associated with incident cardiovascular disorders, suggesting their significant role in the pathogenesis of CVD. Special attention has been paid to the group of branched-chain amino acids (BCAA), leucine, isoleucine, and valine, since their plasma values are frequently found in high concentrations in individuals with CVD risk. Nevertheless, dietary BCAA, leucine in particular, have been associated with improved indicators of atherosclerosis. Therefore, their potential role in the process of atherogenesis and concomitant CVD development remains unclear. Macrophages play pivotal roles in the development of atherosclerosis. They can accumulate high amounts of circulating lipids, through a process known as macrophage foam cell formation, and initiate the atherogenesis process. We have recently screened for anti- or pro-atherogenic amino acids in the macrophage model system. Our study showed that glycine, cysteine, alanine, leucine, glutamate, and glutamine significantly affected macrophage atherogenicity mainly through modulation of the cellular triglyceride metabolism. The anti-atherogenic properties of glycine and leucine, and the pro-atherogenic effects of glutamine, were also confirmed in vivo. Further investigation is warranted to define the role of these amino acids in atherosclerosis and CVD, which may serve as a basis for the development of anti-atherogenic nutritional and therapeutic approaches.

Leucine supplementation attenuates macrophage foam-cell formation: Studies in humans, mice, and cultured macrophages

Whereas atherogenicity of dietary lipids has been largely studied, relatively little is known about the possible contribution of dietary amino acids to macrophage foam-cell formation, a hallmark of early atherogenesis. Recently, we showed that leucine has antiatherogenic properties in the macrophage model system. In this study, an in-depth investigation of the role of leucine in macrophage lipid metabolism was conducted by supplementing humans, mice, or cultured macrophages with leucine. Macrophage incubation with serum obtained from healthy adults supplemented with leucine (5 g/d, 3 weeks) significantly decreased cellular cholesterol mass by inhibiting the rate of cholesterol biosynthesis and increasing cholesterol efflux from macrophages. Similarly, leucine supplementation to C57BL/6 mice (8 weeks) resulted in decreased cholesterol content in their harvested peritoneal macrophages (MPM) in relation with reduced cholesterol biosynthesis rate. Studies in J774A.1 murine macrophages revealed that leucine dose-dependently decreased cellular cholesterol and triglyceride mass. Macrophages treated with leucine (0.2 mM) showed attenuated uptake of very low-density lipoproteins and triglyceride biosynthesis rate, with a concurrent down-regulation of diacylglycerol acyltransferase-1, a key enzyme catalyzing triglyceride biosynthesis in macrophages. Similar effects were observed when macrophages were treated with α-ketoisocaproate, a key leucine metabolite. Finally, both in vivo and in vitro leucine supplementation significantly improved macrophage mitochondrial respiration and ATP production. The above studies, conducted in human, mice, and cultured macrophages, highlight a protective role for leucine attenuating macrophage foam-cell formation by mechanisms related to the metabolism of cholesterol, triglycerides, and energy production. © 2018 BioFactors, 44(3):245-262, 2018.

Comparison of modified Matyash method to conventional solvent systems for polar metabolite and lipid extractions

In the last decade, metabolomics has experienced significant advances in the throughput and robustness of analytical methodologies. Yet the preparation of biofluids and low-mass tissue samples remains a laborious and potentially inconsistent manual process, and a significant bottleneck for high-throughput metabolomics. To address this, we have compared three different sample extraction solvent systems in three diverse sample types with the purpose of selecting an optimum protocol for subsequent automation of sample preparation. We have investigated and re-optimised the solvent ratios in the recently introduced methyl tert-butyl ether (MTBE)/methanol/water solvent system (here termed modified Matyash; 2.6/2.0/2.4, v/v/v) and compared it to the original Matyash method (10/3/2.5, v/v/v) and the conventional chloroform/methanol/water (stepwise Bligh and Dyer, 2.0/2.0/1.8, v/v/v) using two biofluids (human serum and urine) and one tissue (whole Daphnia magna). This is the first report of the use of the Matyash method for extracting metabolites from the US National Institutes of Health (NIH) model organism D. magna. Extracted samples were analysed by non-targeted direct infusion mass spectrometry metabolomics or LC-MS metabolomics. Overall, the modified Matyash method yielded a higher number of peaks and putatively annotated metabolites compared to the original Matyash method (1-29% more peaks and 1-30% more metabolites) and the Bligh and Dyer method (4-20% more peaks and 1-41% more metabolites). Additionally the modified Matyash method was superior when considering metabolite intensities. The reproducibility of the modified Matyash method was higher than other methods (in 10 out of 12 datasets, compared to the original Matyash method; and in 8 out of 12 datasets, compared to the Bligh and Dyer method), based upon the observation of a lower mRSD of peak intensities. In conclusion, the modified Matyash method tended to provide a higher yield and reproducibility for most sample types in this study compared to two widely used methods.

Effect of Dietary Counseling on a Comprehensive Metabolic Profile from Childhood to Adulthood

OBJECTIVES

To study the effects of repeated, infancy-onset dietary counseling on a detailed metabolic profile. Effects of dietary saturated fat replacement on circulating concentrations of metabolic biomarkers still remain unknown.

STUDY DESIGN

The Special Turku Coronary Risk Factor Intervention Project (STRIP) study is a longitudinal, randomized atherosclerosis prevention trial in which repeated dietary counseling aimed at reducing the proportion of saturated fat intake. Nuclear magnetic resonance metabolomics quantified circulating metabolites from serum samples assessed at age 9 (n = 554), 11 (n = 553), 13 (n = 508), 15 (n = 517), 17 (n = 457), and 19 (n = 417) years.

RESULTS

The intervention reduced dietary intake of saturated fat (mean difference in daily percentage of total energy intake: -2.1 [95% CI -1.9 to -2.3]) and increased intake of polyunsaturated fat (0.6 [0.5-0.7]). The dietary counseling intervention led to greater serum proportions of polyunsaturated fatty acids (P < .001), with greater proportions of both circulating omega-3 (P = .02) and omega-6 (P < .001) fatty acids. The proportion of saturated fatty acids in serum was lower for both boys and girls in the intervention group (P < .001), whereas the serum proportion of monounsaturated fat was lower for boys in the intervention group only (P < .001). The intervention also reduced circulating intermediate-density lipoprotein and low-density lipoprotein lipid concentrations (P < .01). Dietary intervention effects on nonlipid biomarkers were minor except from greater concentrations of glutamine in the intervention group.

CONCLUSIONS

Repeated dietary counseling from infancy to early adulthood yielded favorable effects on multiple circulating fatty acids and lipoprotein subclass lipids, particularly in boys. These molecular effects substantiate the beneficial role of saturated fat replacement on the metabolic risk profile.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT00223600.

Metabolic profiling of intra- and extracranial carotid artery atherosclerosis

BACKGROUND AND AIMS

Increasing evidence shows that intracranial carotid artery atherosclerosis may develop under the influence of a differential metabolic risk factor profile than atherosclerosis in the extracranial part of the carotid artery. To further elucidate these differences, we investigated associations of a wide range of circulating metabolites with intracranial and extracranial carotid artery atherosclerosis.

METHODS

From the population-based Rotterdam Study, blood samples from 1111 participants were used to determine a wide range of metabolites by proton nuclear magnetic resonance (NMR). Moreover, these participants underwent non-contrast computed tomography of the neck and head to quantify the amount of extra- and intracranial carotid artery calcification (ECAC and ICAC), as a proxy of atherosclerosis. We assessed associations of the metabolites with ICAC and ECAC and compared the metabolic association patterns of the two.

RESULTS

We found that one standard deviation (SD) increase in concentration of 3-hydroxybutyrate, a ketone body, was significantly associated with a 0.11 SD increase in ICAC volume (p = 1.8 × 10^-4). When we compared the metabolic association pattern of ICAC with that of ECAC, we observed differences in glycolysis-related metabolite measures, lipoprotein subfractions, and amino acids. Interestingly, glycoprotein acetyls were associated with calcification in both studied vessel beds. These associations were most prominent in men.

CONCLUSIONS

We found that a higher circulating level of 3-hydroxybutyrate was associated with an increase in ICAC. Furthermore, we found differences in metabolic association patterns of ICAC and ECAC, providing further evidence for location-specific differences in the etiology of atherosclerosis.

Whole-Transcriptome Sequencing: a Powerful Tool for Vascular Tissue Engineering and Endothelial Mechanobiology

Among applicable high-throughput techniques in cardiovascular biology, whole-transcriptome sequencing is of particular use. By utilizing RNA that is isolated from virtually all cells and tissues, the entire transcriptome can be evaluated. In comparison with other high-throughput approaches, RNA sequencing is characterized by a relatively low-cost and large data output, which permits a comprehensive analysis of spatiotemporal variation in the gene expression profile. Both shear stress and cyclic strain exert hemodynamic force upon the arterial endothelium and are considered to be crucial determinants of endothelial physiology. Laminar blood flow results in a high shear stress that promotes atheroresistant endothelial phenotype, while a turbulent, oscillatory flow yields a pathologically low shear stress that disturbs endothelial homeostasis, making respective arterial segments prone to atherosclerosis. Severe atherosclerosis significantly impairs blood supply to the organs and frequently requires bypass surgery or an arterial replacement surgery that requires tissue-engineered vascular grafts. To provide insight into patterns of gene expression in endothelial cells in native or bioartificial arteries under different biomechanical conditions, this article discusses applications of whole-transcriptome sequencing in endothelial mechanobiology and vascular tissue engineering.

Increased Levels of Circulating Fatty Acids Are Associated with Protective Effects against Future Cardiovascular Events in Nondiabetics

Cardiovascular disease (CVD) is a major cause of morbidity and mortality worldwide, particularly in individuals with diabetes. The current study objective was to determine the circulating metabolite profiles associated with the risk of future cardiovascular events, with emphasis on diabetes status. Nontargeted metabolomics analysis was performed by LC-HRMS in combination with targeted quantification of eicosanoids and endocannabinoids. Plasma from 375 individuals from the IMPROVE pan-European cohort was included in a case-control study design. Following data processing, the three metabolite data sets were concatenated to produce a single data set of 267 identified metabolites. Factor analysis identified six factors that described 26.6% of the variability in the given set of predictors. An association with cardiovascular events was only observed for one factor following adjustment (p = 0.026). From this factor, we identified a free fatty acid signature (n = 10 lipids, including saturated, monounsaturated, and polyunsaturated fatty acids) that was associated with lower risk of future cardiovascular events in nondiabetics only (OR = 0.65, 0.27-0.80 95% CI, p = 0.030), whereas no association was observed among diabetic individuals. These observations support the hypothesis that increased levels of circulating omega-6 and omega-3 fatty acids are associated with protective effects against future cardiovascular events. However, these effects were only observed in the nondiabetic population, further highlighting the need for patient stratification in clinical investigations.

Improvement of myocardial infarction risk prediction via inflammation-associated metabolite biomarkers

OBJECTIVE

The comprehensive assaying of low-molecular-weight compounds, for example, metabolomics, provides a unique tool to uncover novel biomarkers and understand pathways underlying myocardial infarction (MI). We used a targeted metabolomics approach to identify biomarkers for MI and evaluate their involvement in the pathogenesis of MI.

METHODS AND RESULTS

Using three independent, prospective cohorts (KORA S4, KORA S2 and AGES-REFINE), totalling 2257 participants without a history of MI at baseline, we identified metabolites associated with incident MI (266 cases). We also investigated the association between the metabolites and high-sensitivity C reactive protein (hsCRP) to understand the relation between these metabolites and systemic inflammation. Out of 140 metabolites, 16 were nominally associated (p<0.05) with incident MI in KORA S4. Three metabolites, arginine and two lysophosphatidylcholines (LPC 17:0 and LPC 18:2), were selected as biomarkers via a backward stepwise selection procedure in the KORA S4 and were significant (p<0.0003) in a meta-analysis comprising all three studies including KORA S2 and AGES-REFINE. Furthermore, these three metabolites increased the predictive value of the Framingham risk score, increasing the area under the receiver operating characteristic score in KORA S4 (from 0.70 to 0.78, p=0.001) and AGES-REFINE study (from 0.70 to 0.76, p=0.02), but was not observed in KORA S2. The metabolite biomarkers attenuated the association between hsCRP and MI, indicating a potential link to systemic inflammatory processes.

CONCLUSIONS

We identified three metabolite biomarkers, which in combination increase the predictive value of the Framingham risk score. The attenuation of the hsCRP-MI association by these three metabolites indicates a potential link to systemic inflammation.

Peripheral blood mitochondrial DNA content in relation to circulating metabolites and inflammatory markers: A population study

Mitochondrial DNA (mtDNA) content might undergo significant changes caused by metabolic derangements, oxidative stress and inflammation that lead to development and progression of cardiovascular diseases. We, therefore, investigated in a general population the association of peripheral blood mtDNA content with circulating metabolites and inflammatory markers. We examined 310 subjects (50.6% women; mean age, 53.3 years) randomly selected from a Flemish population. Relative mtDNA content was measured by quantitative real-time PCR in peripheral blood cells. Peak circulating metabolites were quantified using nuclear magnetic resonance spectroscopy. The level of inflammation was assessed via established inflammatory markers. Using Partial Least Squares analysis, we constructed 3 latent factors from the 44 measured metabolites that explained 62.5% and 8.5% of the variance in the contributing metabolites and the mtDNA content, respectively. With adjustments applied, mtDNA content was positively associated with the first latent factor (P = 0.002). We identified 6 metabolites with a major impact on the construction of this latent factor including HDL3 apolipoproteins, tyrosine, fatty acid with αCH2, creatinine, β-glucose and valine. We summarized them into a single composite metabolite score. We observed a negative association between the composite metabolic score and mtDNA content (P = 0.001). We also found that mtDNA content was inversely associated with inflammatory markers including hs-CRP, hs-IL6, white blood cell and neutrophil counts as well as neutrophil-to-lymphocyte ratio (P≤0.0024). We demonstrated that in a general population relative peripheral blood mtDNA content was associated with circulating metabolites indicative of perturbed lipid metabolism and with inflammatory biomarkers.

Clinical usefulness of metabolic risk factors to identify young asymptomatic women adults with subclinical atherosclerosis: A cross-sectional study

Interventions of cardiovascular disease should be implemented in early ages. But most studies were performed in middle aged or elderly adults because of the low prevalence in young, especially for women. We investigate the association between metabolic risk factors and subclinical atherosclerosis in young asymptomatic women adults, using carotid intima-media thickness (CIMT) as a marker of the atherosclerotic process.We performed a cross-sectional study of 950 Chinese young asymptomatic women adults (37.28 ± 5.16 years) who underwent a routine health screening examination. Triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), total cholesterol (TC), fasting blood glucose (FBG), homocysteine (HCY), gamma glutamyltransferase (GGT), uric acid, and CIMT were measured.Out of 950 subjects, 16 (1.7%) were detected with increased CIMT. Significant differences existed in the indicators including age, body mass index (BMI), TC, TG, LDL-C, LDL-C/HDL-C, non-HDL-C, and TC/HDL-C. Although TG, LDL-C, non-HDL-C, TC/HDL-C, and TG/HDL-C were the significant indicators when adjusted for age only, age, LDL-C/HDL-C, FBG, and GGT were the only independent relative indicators of increased CMIT that entered the multivariate model. The area under receiver operating characteristic curve for a linear combination of age, LDL-C/HDL-C, FBG, and GGT was 0.809 (95% confidence interval = 0.712-0.906), superior to any of the variables taken alone (age, AUC = 0.707; FBG, AUC = 0.710; LDL-C/HDL-C, AUC = 0.695; GGT, AUC = 0.648).The combined assessment of age, LDL-C/HDL-C, FBG, and GGT contributes to an early detection for subclinical atherosclerosis, providing guidance to clinicians for women's early interventions of latent cardiovascular disease. Neither of the above four individual indicators is qualified alone.

Metabolic profiling of fatty liver in young and middle-aged adults: Cross-sectional and prospective analyses of the Young Finns Study

Nonalcoholic fatty liver is associated with obesity-related metabolic disturbances, but little is known about the metabolic perturbations preceding fatty liver disease. We performed comprehensive metabolic profiling to assess how circulating metabolites, such as lipoprotein lipids, fatty acids, amino acids, and glycolysis-related metabolites, reflect the presence of and future risk for fatty liver in young adults. Sixty-eight lipids and metabolites were quantified by nuclear magnetic resonance metabolomics in the population-based Young Finns Study from serum collected in 2001 (n = 1,575), 2007 (n = 1,509), and 2011 (n = 2,002). Fatty liver was diagnosed by ultrasound in 2011 when participants were aged 34-49 years (19% prevalence). Cross-sectional associations as well as 4-year and 10-year risks for fatty liver were assessed by logistic regression. Metabolites across multiple pathways were strongly associated with the presence of fatty liver (P < 0.0007 for 60 measures in age-adjusted and sex-adjusted cross-sectional analyses). The strongest direct associations were observed for extremely large very-low-density lipoprotein triglycerides (odds ratio [OR] = 4.86 per 1 standard deviation, 95% confidence interval 3.48-6.78), other very-low-density lipoprotein measures, and branched-chain amino acids (e.g., leucine OR = 2.94, 2.51-3.44). Strong inverse associations were observed for high-density lipoprotein measures, e.g., high-density lipoprotein size (OR = 0.36, 0.30-0.42) and several fatty acids including omega-6 (OR = 0.37, 0.32-0.42). The metabolic associations were attenuated but remained significant after adjusting for waist, physical activity, alcohol consumption, and smoking (P < 0.0007). Similar aberrations in the metabolic profile were observed already 10 years before fatty liver diagnosis.

CONCLUSION

Circulating lipids, fatty acids, and amino acids reflect fatty liver independently of routine metabolic risk factors; these metabolic aberrations appear to precede the development of fatty liver in young adults. (Hepatology 2017;65:491-500).

Effect of Metformin on Metabolites and Relation With Myocardial Infarct Size and Left Ventricular Ejection Fraction After Myocardial Infarction

Background—

Left ventricular ejection fraction (LVEF) and infarct size (ISZ) are key predictors of long-term survival after myocardial infarction (MI). However, little is known about the biochemical pathways driving LV dysfunction after MI. To identify novel biomarkers predicting post-MI LVEF and ISZ, we performed metabolic profiling in the GIPS-III randomized clinical trial (Glycometabolic Intervention as Adjunct to Primary Percutaneous Intervention in ST Elevation Myocardial Infarction). We also investigated the metabolic footprint of metformin, a drug associated with improved post-MI LV function in experimental studies.

Methods and Results—

Participants were patients with ST-segment–elevated MI who were randomly assigned to receive metformin or placebo for 4 months. Blood samples were obtained on admission, 24 hours post-MI, and 4 months post-MI. A total of 233 metabolite measures were quantified using nuclear magnetic resonance spectrometry. LVEF and ISZ were assessed 4 months post-MI. Twenty-four hours post-MI measurements of high-density lipoprotein (HDL) triglycerides (HDL-TG) predicted LVEF (β=1.90 [95% confidence interval (CI), 0.82 to 2.98]; P =6.4×10 −4 ) and ISZ (β=−0.41 [95% CI, −0.60 to −0.21]; P =3.2×10 −5 ). In addition, 24 hours post-MI measurements of medium HDL-TG (β=−0.40 [95% CI, −0.60 to −0.20]; P =6.4×2×10 −5 ), small HDL-TG (β=−0.34 [95% CI, −0.53 to −0.14]; P =7.3×10 −4 ), and the triglyceride content of very large HDL (β=−0.38 [95% CI, −0.58 to −0.18]; P =2.7×10 −4 ) were associated with ISZ. After the 4-month treatment, the phospholipid content of very large HDL was lower in metformin than in placebo-treated patients (28.89% versus 38.79%; P =7.5×10 −5 ); alanine levels were higher in the metformin group (0.46 versus 0.44 mmol/L; P =2.4×10 −4 ).

Conclusions—

HDL triglyceride concentrations predict post-MI LVEF and ISZ. Metformin increases alanine levels and reduces the phospholipid content in very large HDL particles.

Clinical Trial Registration—

URL: https://clinicaltrials.gov/ct2/show/NCT01217307 . Unique Identifier: NCT01217307.

Metabolomic Signature of Coronary Artery Disease in Type 2 Diabetes Mellitus

Coronary artery disease (CAD) is a common complication of type 2 diabetes mellitus (T2D). This case-control study was done to identify metabolites with different concentrations between T2D patients with and without CAD and to characterise implicated metabolic mechanisms relating to CAD. Fasting serum samples of 57 T2D subjects, 26 with (cases) and 31 without CAD (controls), were targeted for metabolite profiling of 163 metabolites. To assess the association between metabolite levels and CAD, partial least squares (PLS) analysis and multivariate logistic regression analysis with adjustment for CAD risk factors and medications were performed. We observed a separation of cases and controls with two classes of metabolites being significantly associated with CAD, including phosphatidylcholines, and serine. Four metabolites being independent from the common CAD risk factors displaying best separation between cases and controls were further selected. Addition of the metabolite concentrations to risk factor analysis raised the area under the receiver-operating-characteristic curve from 0.72 to 0.88 (p = 0.020), providing improved sensitivity and specificity for CAD classification. Serum phospholipid and serine levels independently discriminate T2D patients with and without CAD. Oxidative stress and reduced antioxidative capacity lead to lower metabolite concentrations probably due to changes in membrane composition and accelerated phospholipid degradation.

A Recent Update of Clinical and Research Topics Concerning Adult Moyamoya Disease

A better understanding of moyamoya disease (MMD), such as natural clinical course, surgical outcomes and research, has been obtained. This review article focuses on an giving an update for adult MMD in the Korean population. In this paper, we mainly discuss the results of our domestic investigations including meta-analysis, and related subjects from other countries.

Metabolic profiling of alcohol consumption in 9778 young adults

Background: High alcohol consumption is a major cause of morbidity, yet alcohol is associated with both favourable and adverse effects on cardiometabolic risk markers. We aimed to characterize the associations of usual alcohol consumption with a comprehensive systemic metabolite profile in young adults.

Methods: Cross-sectional associations of alcohol intake with 86 metabolic measures were assessed for 9778 individuals from three population-based cohorts from Finland (age 24–45 years, 52% women). Metabolic changes associated with change in alcohol intake during 6-year follow-up were further examined for 1466 individuals. Alcohol intake was assessed by questionnaires. Circulating lipids, fatty acids and metabolites were quantified by high-throughput nuclear magnetic resonance metabolomics and biochemical assays.

Results: Increased alcohol intake was associated with cardiometabolic risk markers across multiple metabolic pathways, including higher lipid concentrations in HDL subclasses and smaller LDL particle size, increased proportions of monounsaturated fatty acids and decreased proportion of omega-6 fatty acids, lower concentrations of glutamine and citrate (P < 0.001 for 56 metabolic measures). Many metabolic biomarkers displayed U-shaped associations with alcohol consumption. Results were coherent for men and women, consistent across the three cohorts and similar if adjusting for body mass index, smoking and physical activity. The metabolic changes accompanying change in alcohol intake during follow-up resembled the cross-sectional association pattern (R²= 0.83, slope = 0.72 ± 0.04).

Conclusions: Alcohol consumption is associated with a complex metabolic signature, including aberrations in multiple biomarkers for elevated cardiometabolic risk. The metabolic signature tracks with long-term changes in alcohol consumption. These results elucidate the double-edged effects of alcohol on cardiovascular risk.

HDLs in crises

PURPOSE OF REVIEW

The clinical utility of HDLs has been scrutinized upon the publication of Mendelian randomization studies showing no effect of HDL-cholesterol (HDL-C) modifying variants on cardiovascular disease (CVD) outcome. The failures of randomized controlled HDL-C-directed intervention trials have further fueled this skepticism. This general criticism originates from oversimplification that has equated 'HDL-C' with 'HDL' and misconceived both as the 'good cholesterol'.

RECENT FINDINGS

HDL particles are heterogeneous and carry hundreds of different lipids, proteins, and microRNAs. Many of them but not cholesterol, that is, HDL-C, contributes to the multiple protective functions of HDLs that probably evolved to manage potentially life-threatening crises. Inflammatory processes modify the composition of HDL particles as well as their individual protein and lipid components, and, as a consequence, also their functionality. Gain of dominant-negative functions makes dysfunctional HDL a part rather than a solution of the endangering situation. Quantification of HDL particle numbers, distinct proteins or lipids, and modifications thereof as well as bioassays of HDL functionality are currently explored toward their diagnostic performance in risk prediction and monitoring of treatment response.

SUMMARY

Any successful clinical exploitation of HDLs will depend on the identification of the most relevant (dys)functions and their structural correlates. Stringent or prioritized structure-(dys)function relationships may provide biomarkers for better risk assessment and monitoring of treatment response. The most relevant agonists carried by either functional or dysfunctional HDLs as well as their cellular responders are interesting targets for drug development.

Associations of serum LDL particle concentration with carotid intima-media thickness and coronary artery calcification

BACKGROUND

Low-density lipoprotein particle (LDL-P) has recently been found to be a stronger predictor of cardiovascular disease (CVD) than LDL-cholesterol (LDL-C).

OBJECTIVES

Whether LDL-P is associated with subclinical atherosclerosis, independent of LDL-C, as well as other lipid measures has not been fully examined. We aimed to analyze LDL-P associations with measures of subclinical atherosclerosis.

METHODS

We examined 870 Japanese men randomly selected from Kusatsu City, Shiga, Japan, aged 40-79 years from 2006-2008, free of clinical CVD and not using lipid-lowering medication. Cross-sectional associations of lipid measures with carotid intima-media thickness (cIMT) and coronary artery calcification (CAC; >0 Agatston score) were examined.

RESULTS

LDL-P was significantly positively associated with cIMT and maintained this association after adjustments for LDL-C and other lipid measures. Although these lipid measures were positively associated with cIMT, model adjustment for LDL-P removed any significant relationships. Higher LDL-P was associated with a significantly higher odds ratio of CAC and further adjustment for LDL-C did not affect this relationship. In contrast, the LDL-C association with CAC was no longer significant after adjustment for LDL-P. Other lipid measures attenuated associations of LDL-P with CAC. Likewise, associations of these measures with CAC were attenuated when model adjustments for LDL-P were made.

CONCLUSIONS

In a community-based sample of Japanese men, free of clinical CVD, LDL-P was a robust marker for subclinical atherosclerosis, independent of LDL-C and other lipid measures. Associations of LDL-C and other lipid measures with either cIMT or CAC were generally not independent of LDL-P.

History and future of omega-3 fatty acids in cardiovascular disease

BACKGROUND/OBJECTIVES

Epidemiological, diet-based, and some interventional outcomes studies suggest that polyunsaturated omega-3 fatty acids (OM3FAs), specifically eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), confer cardiovascular protection in some patient populations. This review examines the historical context of OM3FAs in cardiovascular disease and future perspectives on the place of OM3FA products in reducing cardiovascular risk.

METHODS

Relevant articles were identified via PubMed/Medline and Google Scholar searches through 2015 and through reference lists of selected publications. Articles determined by the authors to be relevant to the topic of this review were included.

RESULTS

Review of the identified articles indicated that inconsistent results among interventional outcomes studies have been attributed to use of low doses of OM3FAs, patient cohorts with non-elevated triglyceride (TG) levels, differential use of concomitant statin therapy, and study designs with insufficient statistical power. Several prescription OM3FA products are now approved as an adjunct to diet to reduce TG levels in adults with severe (≥500 mg/dL) hypertriglyceridemia. Most formulations contain both EPA and DHA; one formulation contains purified EPA. In randomized controlled trials, these products significantly reduced TG levels in patients with very high TG levels (≥500 mg/dL [≥13.0 mmol/L]) and in statin-treated patients with high TG levels (200-499 mg/dL [5.2-12.9 mmol/L]). The DHA-containing products raised LDL-C levels in these studies, whereas the EPA-only product had no effect on LDL-C, suggesting that all OM3FA prescription products are not therapeutically equivalent. Besides lowering TG levels, OM3FAs (particularly EPA) exert anti-inflammatory effects and may slow multiple atherogenic processes. Two well designed interventional outcomes studies (REDUCE-IT and STRENGTH) are evaluating prescription-strength, high-dose OM3FAs (4 g/day) in statin-treated patients with persistently high TG levels.

CONCLUSIONS

The results of the ongoing prescription-strength, high-dose OM3FA interventional trials will help define the potential role of OM3FAs in addressing residual cardiovascular risk despite statin therapy.

Quantitative serum nuclear magnetic resonance metabolomics in cardiovascular epidemiology and genetics

Metabolomics is becoming common in epidemiology due to recent developments in quantitative profiling technologies and appealing results from their applications for understanding health and disease. Our team has developed an automated high-throughput serum NMR metabolomics platform that provides quantitative molecular data on 14 lipoprotein subclasses, their lipid concentrations and composition, apolipoprotein A-I and B, multiple cholesterol and triglyceride measures, albumin, various fatty acids as well as on numerous low-molecular-weight metabolites, including amino acids, glycolysis related measures and ketone bodies. The molar concentrations of these measures are obtained from a single serum sample with costs comparable to standard lipid measurements. We have analyzed almost 250 000 samples from around 100 epidemiological cohorts and biobanks and the new international set-up of multiple platforms will allow an annual throughput of more than 250 000 samples. The molecular data have been used to study type 1 and type 2 diabetes etiology as well as to characterize the molecular reflections of the metabolic syndrome, long-term physical activity, diet and lipoprotein metabolism. The results have revealed new biomarkers for early atherosclerosis, type 2 diabetes, diabetic nephropathy, cardiovascular disease and all-cause mortality. We have also combined genomics and metabolomics in diverse studies. We envision that quantitative high-throughput NMR metabolomics will be incorporated as a routine in large biobanks; this would make perfect sense both from the biological research and cost point of view - the standard output of over 200 molecular measures would vastly extend the relevance of the sample collections and make many separate clinical chemistry assays redundant.

Metabolomics reveals impaired maturation of HDL particles in adolescents with hyperinsulinaemic androgen excess

Hyperinsulinaemic androgen excess (HIAE) in prepubertal and pubertal girls usually precedes a broader pathological phenotype in adulthood that is associated with anovulatory infertility, metabolic syndrome and type 2 diabetes. The metabolic derangements that determine these long-term health risks remain to be clarified. Here we use NMR and MS-based metabolomics to show that serum levels of methionine sulfoxide in HIAE girls are an indicator of the degree of oxidation of methionine-148 residue in apolipoprotein-A1. Oxidation of apo-A1 in methionine-148, in turn, leads to an impaired maturation of high-density lipoproteins (HDL) that is reflected in a decline of large HDL particles. Notably, such metabolic alterations occur in the absence of impaired glucose tolerance, hyperglycemia and hypertriglyceridemia, and were partially restored after 18 months of treatment with a low-dose combination of pioglitazone, metformin and flutamide.

Sex hormone-binding globulin associations with circulating lipids and metabolites and the risk for type 2 diabetes: observational and causal effect estimates

BACKGROUND

The causal role of circulating sex hormone-binding globulin (SHBG) for type 2 diabetes is controversial. Information on the relations between SHBG and new biomarkers of cardiometabolic risk is scarce.

METHODS

We applied quantitative nuclear magnetic resonance metabolomics in three Finnish population-based cohorts to comprehensively profile circulating lipids and metabolites and study their associations with SHBG. Mendelian randomization was used to examine potential causality of SHBG on the metabolic measures and insulin resistance. Prospective associations and causal effect estimates of SHBG on type 2 diabetes were assessed via meta-analysis including summary statistics from the DIAGRAM consortium.

RESULTS

In cross-sectional analysis in 6475 young adults (mean age 31, 57% men), higher SHBG was linked with a more favourable cardiometabolic risk profile, including associations with lipoprotein subclasses, fatty acid composition, amino acids, ketone bodies and inflammation-linked glycoproteins. Prospective analysis of 1377 young adults with 6-year follow-up indicated that SHBG is also associated with future insulin resistance. Mendelian randomization suggested only minor, if any, causal effects of SHBG on lipid and metabolite measures and insulin resistance(n = 10,895).Causal effect estimates on type 2 diabetes for 41,439 cases and 103,870 controls indicated a causative protective role of SHBG (OR = 0.83 per 1-SD, 95% CI: 0.76, 0.91); however, effects were considerably weaker than observed in meta-analysis of prospective studies [hazard ratio (HR) = 0.47 per 1-SD, 95% CI: 0.41, 0.53].

CONCLUSION

Circulating SHBG is strongly associated with systemic metabolism and predictive for insulin resistance and diabetes. The weaker causal estimates suggest that the observational associations are partly confounded rather than conferred directly via circulating SHBG.

1H-NMR-based metabolomic analysis of cerebrospinal fluid from adult bilateral moyamoya disease: comparison with unilateral moyamoya disease and atherosclerotic stenosis

Although metabolomics has been increasingly used to observe metabolic pattern and disease-specific metabolic markers, metabolite profiling for moyamoya disease (MMD) has not yet been done in adults. This study investigated cerebrospinal fluid (CSF) metabolites specific to bilateral MMD (B-MMD) and compared them to those of unilateral MMD (U-MMD) or atherosclerotic stenosis with hydrogen-1 nuclear magnetic resonance spectroscopy to identify metabolic biomarkers associated with MMD in adults.CSF samples of B-MMD (n = 29), U-MMD (n = 11), and atherosclerotic cerebrovascular disease (ACVD) (n = 8) were recruited. Principal component analysis, partial least square discriminant analysis, and orthogonal projections to latent structure discriminant analysis (OPLS-DA) were done for the comparisons. Diagnostic performance was acquired by prediction of 1 left-out sample from the distinction model constructed with the rest of the samples.B-MMD showed an increase in glutamine (P < 0.001) and taurine (P = 0.004), and a decrease in glucose (P < 0.001), citrate (P = 0.002), and myo-inositol (P = 0.006) than those in ACVD. U-MMD showed a higher level of glutamine (P = 0.005) and taurine (P = 0.034), and a lower level of glutamate (P < 0.004) than those in ACVD. No difference at the metabolite level was observed between B-MMD and U-MMD. Cross-validation with the OPLS-DA model showed a high accuracy for the prediction of MMD.The results of the study suggest that a metabolomics approach may be helpful in confirming MMD and providing a better understanding of MMD pathogenesis. Elevated glutamine in the CSF may be associated with MMD pathogenesis, which was different from ACVD.

Metabolomics in cardiovascular diseases

Cardiovascular diseases (CVDs) are the main cause of death globally. There is a need for the development of specific diagnostic methods, more effective therapeutic procedures as well as drugs, which can decrease the risk of deaths in the course of CVDs. For this reason, better understanding and explanation of molecular pathomechanisms of CVDs are essential. Metabolomics is focused on analysis of metabolites, small molecules which reflect the state of an organism in a certain point of time. Application of metabolomics approach in the investigation of molecular processes responsible for CVDs development may provide valuable information. In this article we overviewed recent reports employing application of untargeted and targeted metabolomic analyses in particular CVDs. Moreover, we focused on applications of various analytical platforms and metabolomics approaches which may contribute to the explanation of the pathomechanisms of different cardiovascular diseases.

The association of metabolic syndrome and its components with brachial-ankle pulse wave velocity in south China

BACKGROUND

Brachial-ankle pulse wave velocity (baPWV) can reflect both central and peripheral arterial stiffness. Metabolic syndrome (MS) and its components may increase arterial stiffness and the risks of cardiovascular diseases. However, the correlation of MS and its components with arterial stiffness has not been not well studied. The aim of this study was to investigate the correlation between MS/its components and arterial stiffness by the measurement of baPWV in south China population.

METHODS

A total of 8599 subjects were selected from those who underwent health examination in our hospital. MS was defined by Joint Scientific Statement. BaPWV, waist circumference, blood pressure (BP), fasting plasma glucose (FPG), lipid profile and serum uric acid (UA) were measured. The relationship between baPWV and MS/its components was analyzed.

RESULTS

BaPWV was significantly higher in the subjects with MS than in those without MS (P < 0.001 for both genders). By multivariate regression analysis, all the metabolic components were correlated to baPWV in the male and female subjects except low HDL-C and high UA in the male group. BP and FPG had the strongest correlation factors. The values of baPWV were positively correlated with the advanced age (P < 0.001) and the values of the MS components, and this correlation was stronger in the females than in the males (P < 0.001).

CONCLUSION

Metabolic syndrome and its individual components were positively correlated with baPWV. Monitoring baPWV is helpful to identify early stage of arterial stiffness in those people with MS.

Metabolite profiling and cardiovascular event risk: a prospective study of 3 population-based cohorts

BACKGROUND

High-throughput profiling of circulating metabolites may improve cardiovascular risk prediction over established risk factors.

METHODS AND RESULTS

We applied quantitative nuclear magnetic resonance metabolomics to identify the biomarkers for incident cardiovascular disease during long-term follow-up. Biomarker discovery was conducted in the National Finnish FINRISK study (n=7256; 800 events). Replication and incremental risk prediction was assessed in the Southall and Brent Revisited (SABRE) study (n=2622; 573 events) and British Women's Health and Heart Study (n=3563; 368 events). In targeted analyses of 68 lipids and metabolites, 33 measures were associated with incident cardiovascular events at P<0.0007 after adjusting for age, sex, blood pressure, smoking, diabetes mellitus, and medication. When further adjusting for routine lipids, 4 metabolites were associated with future cardiovascular events in meta-analyses: higher serum phenylalanine (hazard ratio per standard deviation, 1.18; 95% confidence interval, 1.12-1.24; P=4×10(-10)) and monounsaturated fatty acid levels (1.17; 1.11-1.24; P=1×10(-8)) were associated with increased cardiovascular risk, while higher omega-6 fatty acids (0.89; 0.84-0.94; P=6×10(-5)) and docosahexaenoic acid levels (0.90; 0.86-0.95; P=5×10(-5)) were associated with lower risk. A risk score incorporating these 4 biomarkers was derived in FINRISK. Risk prediction estimates were more accurate in the 2 validation cohorts (relative integrated discrimination improvement, 8.8% and 4.3%), albeit discrimination was not enhanced. Risk classification was particularly improved for persons in the 5% to 10% risk range (net reclassification, 27.1% and 15.5%). Biomarker associations were further corroborated with mass spectrometry in FINRISK (n=671) and the Framingham Offspring Study (n=2289).

CONCLUSIONS

Metabolite profiling in large prospective cohorts identified phenylalanine, monounsaturated fatty acids, and polyunsaturated fatty acids as biomarkers for cardiovascular risk. This study substantiates the value of high-throughput metabolomics for biomarker discovery and improved risk assessment.

Mendelian randomization of blood lipids for coronary heart disease

AIMS

To investigate the causal role of high-density lipoprotein cholesterol (HDL-C) and triglycerides in coronary heart disease (CHD) using multiple instrumental variables for Mendelian randomization.

METHODS AND RESULTS

We developed weighted allele scores based on single nucleotide polymorphisms (SNPs) with established associations with HDL-C, triglycerides, and low-density lipoprotein cholesterol (LDL-C). For each trait, we constructed two scores. The first was unrestricted, including all independent SNPs associated with the lipid trait identified from a prior meta-analysis (threshold P < 2 × 10(-6)); and the second a restricted score, filtered to remove any SNPs also associated with either of the other two lipid traits at P ≤ 0.01. Mendelian randomization meta-analyses were conducted in 17 studies including 62,199 participants and 12,099 CHD events. Both the unrestricted and restricted allele scores for LDL-C (42 and 19 SNPs, respectively) associated with CHD. For HDL-C, the unrestricted allele score (48 SNPs) was associated with CHD (OR: 0.53; 95% CI: 0.40, 0.70), per 1 mmol/L higher HDL-C, but neither the restricted allele score (19 SNPs; OR: 0.91; 95% CI: 0.42, 1.98) nor the unrestricted HDL-C allele score adjusted for triglycerides, LDL-C, or statin use (OR: 0.81; 95% CI: 0.44, 1.46) showed a robust association. For triglycerides, the unrestricted allele score (67 SNPs) and the restricted allele score (27 SNPs) were both associated with CHD (OR: 1.62; 95% CI: 1.24, 2.11 and 1.61; 95% CI: 1.00, 2.59, respectively) per 1-log unit increment. However, the unrestricted triglyceride score adjusted for HDL-C, LDL-C, and statin use gave an OR for CHD of 1.01 (95% CI: 0.59, 1.75).

CONCLUSION

The genetic findings support a causal effect of triglycerides on CHD risk, but a causal role for HDL-C, though possible, remains less certain.

Liposcale: a novel advanced lipoprotein test based on 2D diffusion-ordered 1H NMR spectroscopy

Determination of lipoprotein particle size and number using advanced lipoprotein tests (ALTs) is of particular importance to improve cardiovascular risk prediction. Here we present the Liposcale test, a novel ALT based on 2D diffusion-ordered (1)H NMR spectroscopy. Our method uses diffusion coefficients to provide a direct measure of the mean particle sizes and numbers. Using 177 plasma samples from healthy individuals and the concentration of ApoB and ApoA from isolated lipoprotein fractions, our test showed a stronger correlation between the NMR-derived lipoprotein particle numbers and apolipoprotein concentrations than the LipoProfile(®) test commercialized by Liposcience. We also converted LDL particle numbers to ApoB equivalents (milligrams per deciliter) and our test yielded similar values of LDL-ApoB to the LipoProfile(®) test (absolute mean bias of 8.5 and 7.4 mg/dl, respectively). In addition, our HDL particle number values were more concordant with the calibrated values determined recently using ion mobility. Finally, principal component analysis distinguished type 2 diabetic patients with and without atherogenic dyslipidemia (AD) on a second cohort of 307 subjects characterized using the Liposcale test (area under the curve = 0.88) and showed concordant relationships between variables explaining AD. Altogether, our method provides reproducible and reliable characterization of lipoprotein particles and it is applicable to pathological states such as AD.

Epidemiology: disease associations and modulators of HDL-related biomarkers

Epidemiological studies have shown an inverse association between high-density lipoprotein cholesterol (HDL-C) levels and risk of ischemic heart disease. In addition, a low level of HDL-C has been shown to be a risk factor for other diseases not related to atherosclerosis. However, recent studies have not supported a causal effect of HDL-C in the development of atherosclerosis. Furthermore, new drugs markedly elevating HDL-C levels have been disappointing with respect to clinical endpoints. Earlier, most studies have focused almost exclusively on the total HDL-C without regard to the chemical composition or multiple subclasses of HDL particles. Recently, there have been efforts to dissect the HDL fraction into as many well-defined subfractions and individual molecules of HDL particles as possible. On the other hand, the focus is shifting from the structure and composition to the function of HDL particles. Biomarkers and mechanisms that could potentially explain the beneficial characteristics of HDL particles unrelated to their cholesterol content have been sought with sophisticated methods such as proteomics, lipidomics, metabonomics, and function studies including efflux capacity. These new approaches have been used in order to resolve the complex effects of diseases, conditions, environmental factors, and genes in relation to the protective role of HDL but high-throughput methods are still needed for large-scale epidemiological studies.

Lipoprotein subclass metabolism in nonalcoholic steatohepatitis

Nonalcoholic steatohepatitis (NASH) is associated with increased synthesis of triglycerides and cholesterol coupled with increased VLDL synthesis in the liver. In addition, increased cholesterol content in the liver associates with NASH. Here we study the association of lipoprotein subclass metabolism with NASH. To this aim, liver biopsies from 116 morbidly obese individuals [age 47.3 ± 8.7 (mean ± SD) years, BMI 45.1 ± 6.1 kg/m², 39 men and 77 women] were used for histological assessment. Proton NMR spectroscopy was used to measure lipid concentrations of 14 lipoprotein subclasses in native serum samples at baseline and after obesity surgery. We observed that total lipid concentration of VLDL and LDL subclasses, but not HDL subclasses, associated with NASH [false discovery rate (FDR) < 0.1]. More specifically, total lipid and cholesterol concentration of VLDL and LDL subclasses associated with inflammation, fibrosis, and cell injury (FDR < 0.1), independent of steatosis. Cholesterol concentration of all VLDL subclasses also correlated with total and free cholesterol content in the liver. All NASH-related changes in lipoprotein subclasses were reversed by obesity surgery. High total lipid and cholesterol concentration of serum VLDL and LDL subclasses are linked to cholesterol accumulation in the liver and to liver cell injury in NASH.