Association of Circulating Metabolites in Plasma or Serum and Risk of Stroke: Meta-analysis From 7 Prospective Cohorts

Causal relationship between genetically determined plasma metabolites and stroke: A two sample Mendelian randomization study

INTRODUCTION

This study investigates the causal relationship between plasma metabolites and stroke.

METHOD

The primary analytical approach employed was the inverse variance weighted (IVW) method, complemented by the weighted median (WM) and MR Egger methods for Additionally, validation of the identified plasma metabolites was performed using the Steiger test and LD linkage disequilibrium score. Furthermore, the main results were confirmed through data from the UK Biobank.

RESULT

The IVW analysis revealed the most notable negative association found in X-17335 levels (OR [95 % CI]: 0.82 [0.72, 0.94]). On the other hand, the strongest positive effect was seen in the 5'-homophase (AMP) to phase ratio (OR [95 % CI]: 1.17 [1.03, 1.32]). Moving on to the validation dataset, the most significant positive effect was observed in the 13 HODE+9-HODE levels (OR [95 % CI]: 0.996 [0.993, 0.999]), whereas the most significant negative effect was seen in the Dihydroxide levels (OR [95 % CI]: 1.004 [1.00, 1.007]). Notably, Alpha ketoglutarate levels exhibited strong causal effects in both datasets (OR 0.908 [0.841, 0.981], p = 0.0144). Enrichment analysis highlighted the association of Alpha ketoglutarate levels with five plasma metabolites in metabolic pathways relevant to stroke, specifically Arginine biosynthesis, Butanoate metabolism, Citrate cycle (TCA cycle), Alanine, aspartate, and glutamate metabolism, and Lipid acid metabolism, all linked to oxoglutaric acid.

CONCLUSION

The discovery dataset showed the most significant positive effect of the 5'-homophase (AMP) to phase ratio, while the validation dataset revealed the most significant positive effect of the 13 HODE+9-HODE levels. Additionally, alpha ketoglutarate may offer a potential protective effect on stroke by influencing five metabolic pathways that intersect with Oxoglutaric acid during the progression of the condition.

Metabolomic discoveries for early diagnosis and traditional Chinese medicine efficacy in ischemic stroke

Ischemic stroke (IS), a devastating cerebrovascular accident, presents with high mortality and morbidity. Following IS onset, a cascade of pathological changes, including excitotoxicity, inflammatory damage, and blood-brain barrier disruption, significantly impacts prognosis. However, current clinical practices struggle with early diagnosis and identifying these alterations. Metabolomics, a powerful tool in systems biology, offers a promising avenue for uncovering early diagnostic biomarkers for IS. By analyzing dynamic metabolic profiles, metabolomics can not only aid in identifying early IS biomarkers but also evaluate Traditional Chinese Medicine (TCM) efficacy and explore its mechanisms of action in IS treatment. Animal studies demonstrate that TCM interventions modulate specific metabolite levels, potentially reflecting their therapeutic effects. Identifying relevant metabolites in cerebral ischemia patients holds immense potential for early diagnosis and improved outcomes. This review focuses on recent metabolomic discoveries of potential early diagnostic biomarkers for IS. We explore variations in metabolites observed across different ages, genders, disease severity, and stages. Additionally, the review examines how specific TCM extracts influence IS development through metabolic changes, potentially revealing their mechanisms of action. Finally, we emphasize the importance of integrating metabolomics with other omics approaches for a comprehensive understanding of IS pathophysiology and TCM efficacy, paving the way for precision medicine in IS management.

Associations of Plasma Metabolites With Risks of Incident Stroke and Its Subtypes in Chinese Adults

BACKGROUND

Metabolomics studies have identified various metabolic markers associated with stroke risk, yet much uncertainty persists regarding heterogeneity in these associations between different stroke subtypes. We aimed to examine metabolic profiles associated with incident stroke and its subtypes in Chinese adults.

METHODS AND RESULTS

We performed a nested case-control study within the Dongfeng-Tongji cohort, including 1029 and 266 incident cases of ischemic stroke (IS) and hemorrhagic stroke (HS), respectively, with a mean follow-up period of 6.1±2.3 years. Fifty-five metabolites in fasting plasma were measured by ultra-high-performance liquid chromatography-mass spectrometry. We examined the associations of metabolites with the risks of total stroke, IS, and HS, with a focus on the comparison of associations of plasma metabolite with IS and HS, using conditional logistic regression. We found that increased levels of asymmetrical/symmetrical dimethylarginine and glutamate were significantly associated with elevated risk of total stroke (odds ratios and 95%, 1.20 [1.08-1.34] and 1.22 [1.09-1.36], respectively; both Benjamini-Hochberg-adjusted P <0.05). When examining stroke subtypes, asymmetrical/symmetrical dimethylarginine was nominally associated with both IS and HS (odds ratios [95% CIs]: 1.16 [1.03-1.31] and 1.39 [1.07-1.81], respectively), while glutamate was associated with only IS (odds ratios [95% CI]: 1.26 [1.11-1.43]). The associations of glutamate with IS risk were significantly stronger among participants with hypertension and diabetes than among those without these diseases (both P for interaction <0.05).

CONCLUSIONS

This study validated the positive associations of asymmetrical/symmetrical dimethylarginine and glutamate with stroke risk, mainly that of IS, in a Chinese population, and revealed a novel unanimous association of with both IS and HS. Our findings provided potential intervention targets for stroke prevention.

Exploring the causal association between genetically determined circulating metabolome and hemorrhagic stroke

Background

Hemorrhagic stroke (HS), a leading cause of death and disability worldwide, has not been clarified in terms of the underlying biomolecular mechanisms of its development. Circulating metabolites have been closely associated with HS in recent years. Therefore, we explored the causal association between circulating metabolomes and HS using Mendelian randomization (MR) analysis and identified the molecular mechanisms of effects.

Methods

We assessed the causal relationship between circulating serum metabolites (CSMs) and HS using a bidirectional two-sample MR method supplemented with five ways: weighted median, MR Egger, simple mode, weighted mode, and MR-PRESSO. The Cochran Q-test, MR-Egger intercept test, and MR-PRESSO served for the sensitivity analyses. The Steiger test and reverse MR were used to estimate reverse causality. Metabolic pathway analyses were performed using MetaboAnalyst 5.0, and genetic effects were assessed by linkage disequilibrium score regression. Significant metabolites were further synthesized using meta-analysis, and we used multivariate MR to correct for common confounders.

Results

We finally recognized four metabolites, biliverdin (OR 0.62, 95% CI 0.40-0.96, PMVMR = 0.030), linoleate (18. 2n6) (OR 0.20, 95% CI 0.08-0.54, PMVMR = 0.001),1-eicosadienoylglycerophosphocholine* (OR 2.21, 95% CI 1.02-4.76, PMVMR = 0.044),7-alpha-hydroxy-3 -oxo-4-cholestenoate (7-Hoca) (OR 0.27, 95% CI 0.09-0.77, PMVMR = 0.015) with significant causal relation to HS.

Conclusion

We demonstrated significant causal associations between circulating serum metabolites and hemorrhagic stroke. Monitoring, diagnosis, and treatment of hemorrhagic stroke by serum metabolites might be a valuable approach.

NMR based Serum metabolomics revealed metabolic signatures associated with oxidative stress and mitochondrial damage in brain stroke

Brain stroke (BS, also known as a cerebrovascular accident), represents a serious global health crisis. It has been a leading cause of permanent disability and unfortunately, frequent fatalities due to lack of timely medical intervention. While progress has been made in prevention and management, the complexities and consequences of stroke continue to pose significant challenges, especially, its impact on patient's quality of life and independence. During stroke, there is a substantial decrease in oxygen supply to the brain leading to alteration of cellular metabolic pathways, including those involved in mitochondrial-damage, leading to mitochondrial-dysfunction. The present proof-of-the-concept metabolomics study has been performed to gain insights into the metabolic pathways altered following a brain stroke and discover new potential targets for timely interventions to mitigate the effects of cellular and mitochondrial damage in BS. The serum metabolic profiles of 108 BS-patients were measured using 800 MHz NMR spectroscopy and compared with 60 age and sex matched normal control (NC) subjects. Compared to NC, the serum levels of glutamate, TCA-cycle intermediates (such as citrate, succinate, etc.), and membrane metabolites (betaine, choline, etc.) were found to be decreased BS patients, whereas those of methionine, mannose, mannitol, phenylalanine, urea, creatine and organic acids (such as 3-hydroxybutyrate and acetone) were found to be elevated in BS patients. These metabolic changes hinted towards hypoxia mediated mitochondrial dysfunction in BS-patients. Further, the area under receiver operating characteristic curve (ROC) values for five metabolic features (methionine, mannitol, phenylalanine, mannose and urea) found to be more than 0.9 suggesting their high sensitivity and specificity for differentiating BS from NC subjects.

Causal role of lipid metabolome on the risk of ischemic stroke, its etiological subtypes, and long-term outcome: A Mendelian randomization study

BACKGROUND AND AIMS

The lipid profile is consistently associated with coronary artery disease (CAD) and ischemic stroke (IS). However, the lipoprotein subfractions have not been deeply explored in stroke subtypes, especially in IS outcome.

METHODS

We performed two-sample Mendelian randomization (MR) analysis using 92 lipid traits measured by nuclear magnetic resonance in 115,000 subjects from the UK Biobank. Data for genetic associations with IS, its subtypes, and long-term outcome (LTO) were obtained from three cohorts of European ancestry: GIGASTROKE (73,652 cases, 1,234,808 controls), GODS (n = 1791) and GISCOME (n = 6165). Results obtained using CARDIoGRAMPlusC4D were used to identify differences with CAD.

RESULTS

Genetically determined low concentration of medium high-density lipoprotein (HDL) particles (odds ratio (OR) = 0.92, 95% CI 0.88-0.96; p = 3.6 × 10-4) and its cholesterol content (OR = 0.92, 95% CI 0.88-0.96; p = 1.9 × 10-4) showed causal associations with an increased risk of stroke. Genetic predisposition to high apolipoprotein (apo)B to apoA-I ratio was causally associated with an increased risk of IS (OR = 1.12, 95% CI 1.06-1.18, p = 1.1 × 10-4), and a highly suggestive association was found between non-esterified cholesterol in low-density lipoprotein (LDL) and increased risk of atherothrombotic stroke (LAS) (OR = 1.35, 95% CI 1.10-1.66; p = 4.0 × 10-3). Low cholesterol in small and medium LDL was suggestively associated with poor LTO.

CONCLUSIONS

Our results support that low medium HDL concentration was causally associated with an increased stroke risk, while high levels of non-esterified cholesterol in LDL were suggestively associated with an increased risk of LAS and with a better LTO.

Effects of Nightshift Work on Blood Metabolites in Female Nurses and Paramedic Staff: A Cross-sectional Study

Nightshift work disturbs the circadian rhythm, which might contribute to the development of cardio-metabolic disorders. In this cross-sectional study, we aimed to gain insight into perturbations of disease relevant metabolic pathways due to nightshift work. We characterized the metabolic profiles of 237 female nurses and paramedic staff participating in the Klokwerk study using the Nightingale Health platform. We performed analyses on plasma levels of 225 metabolites, including cholesterol, triglycerides, fatty acids, and amino acids. Using both principal component- and univariate-regression, we compared metabolic profiles of nightshift workers to metabolic profiles from workers that did not work night shifts (defined as day workers). We also assessed whether differential effects were observed between recently started versus more experienced workers. Within the group of nightshift workers, we compared metabolic profiles measured right after a nightshift with metabolic profiles measured on a day when no nightshift work was conducted. We observed evidence for an impact of nightshift work on the presence of unfavorable fatty acid profiles in blood. Amongst the fatty acids, effects were most prominent for PUFA/FA ratios (consistently decreased) and SFA/FA ratios (consistently elevated). This pattern of less favorable fatty acid profiles was also observed in samples collected directly after a night shift. Amino acid levels (histidine, glutamine, isoleucine, and leucine) and lipoproteins (especially HDL-cholesterol, VLDL-cholesterol, and triglycerides) were elevated when comparing nightshift workers with day workers. Amino acid levels were decreased in the samples that were collected directly after working a nightshift (compared to levels in samples that were collected during a non-nightshift period). The observed effects were generally more pronounced in samples collected directly after the nightshift and among recently started compared to more experienced nightshift workers. Our finding of a suggested impact of shift work on impaired lipid metabolism is in line with evidence that links disruption of circadian rhythmicity to obesity and metabolic disorders.

Essential nutrients and cerebral small vessel diseases: a two-sample Mendelian randomization study

Background

Previous studies have suggested a potential association between nutrients and cerebral small vessel disease (CSVD), but this association has not been fully addressed.

Object

We intended to clarify the causal associations between four categories of essential nutrients (amino acids, polyunsaturated fatty acids, minerals and vitamins) and two acute manifestations of CSVD (intracerebral hemorrhage and small vessel stroke) using two-sample Mendelian randomization (MR) analysis.

Method

We obtained European-based large-scale genome-wide association studies (GWASs) related to CSVD (6,255 cases and 233,058 controls) and nutrient concentrations. Causality evaluation mainly included the results of the inverse variance-weighted (IVW) method. The simple median method, the weighted median method and the MR-Egger method were adopted for sensitivity analyses.

Results

For ICH or SVS, increased levels of phenylalanine (OR = 1.188, p < 0.001) and dihomo-gamma-linolenic acid (DGLA) (OR = 1.153, p = 0.001) showed risk effects, while docosapentaenoic acid (DPA) (OR = 0.501, p < 0.001), zinc (OR = 0.919, p < 0.001), and arachidonic acid (OR = 0.966, p = 0.007) showed protective effects. For lobar hemorrhage or SVS, AA (OR = 0.978, p < 0.001), zinc (OR = 0.918, p < 0.001), and retinol (OR = 0.753, p < 0.001) showed risk effects; DPA (OR = 0.682, p = 0.022), gamma-linolenic acid (OR = 0.120, p = 0.033) and 25(OH)D (OR = 0.874, p = 0.040) showed protective effects. For nonlobar hemorrhage or SVS, DGLA (OR = 1.088, p < 0.001) and phenylalanine (OR = 1.175, p = 0.001) showed risk effects.

Conclusion

Our study analyzed the effect of nutrients on CSVD risk from a genetic perspective, with implications for CSVD prevention through nutrient supplementation.

Association of Circulating Metabolites With Racial Disparities in Hypertension and Stroke in the REGARDS Study

BACKGROUND AND OBJECTIVES

In the United States, the risk of stroke is greater among Black compared with that among White individuals. However, the reasons for the difference in stroke incidence are not fully elucidated. We aimed to identify metabolites that account for higher prevalent hypertension and incident ischemic stroke among Black adults.

METHODS

We used a stroke case cohort nested within the REasons for Geographic and Racial Differences in Stroke (REGARDS) study. Targeted metabolomic profiling of 162 plasma metabolites was performed by liquid chromatography-tandem mass spectrometry. We identified metabolites that were associated with prevalent hypertension and incident ischemic stroke and mediated the relationship between hypertension and ischemic stroke by weighted logistic regression, Cox proportional hazard model, and inverse odds ratio weighting mediation analysis.

RESULTS

Incident ischemic stroke cases adjudicated through April 1, 2019 (n = 1,075) were included in the study. The random cohort sample was derived from the full cohort using stratified sampling (n = 968). Among 162 metabolites, gluconic acid was associated with prevalent hypertension in Black adults (odds ratio [OR] 1.86, 95% CI 1.39-2.47, p = 2.58 × 10-5) but not in White adults (OR 1.00, 95% CI 0.80-1.24, p = 0.97; p for interaction = 4.57 × 10-4). Gluconic acid also demonstrated an association with incident ischemic stroke among Black participants (hazard ratio [HR] 1.53, 95% CI 1.28-1.81, p = 1.76 × 10-6) but not White participants (HR 1.16, 95% CI 1.00-1.34, p = 0.057; p for interaction = 0.019). In mediation analysis, gluconic acid mediated 25.4% (95% CI 4.1%-46.8%, p = 0.02) of the association between prevalent hypertension and incident ischemic stroke among Black individuals. Specific socioeconomic factors were linked to elevated gluconic acid level among Black adults in multivariable analysis, including a Southern dietary pattern (β = 0.18, 95% CI 0.08-0.28, p < 0.001), lower educational attainment (β = 0.45, 95% CI 0.19-0.72, p = 0.001), and a lack of exercise (β = 0.26, 95% CI 0.01-0.51, p = 0.045).

DISCUSSION

Gluconic acid is associated with prevalent hypertension and incident ischemic stroke and mediates the relationship between hypertension and ischemic stroke in Black but not White adults. Gluconic acid is a biomarker that is associated with social determinants of health including a Southern diet, low educational attainment, and low physical activity.

Exploration of Metabolic Biomarkers Linking Red Meat Consumption to Ischemic Heart Disease Mortality in the UK Biobank

Growing evidence suggests that red meat consumption is a risk factor for cardiovascular health, with potential sex disparity. The metabolic mechanisms have not been fully understood. Using the UK Biobank, first we examined the associations of unprocessed red meat and processed meat with ischemic heart disease (IHD) mortality overall and by sex using logistic regression. Then, we examined the overall and sex-specific associations of red meat consumption with metabolites using multivariable regression, as well as the associations of selected metabolites with IHD mortality using logistic regression. We further selected metabolic biomarkers that are linked to both red meat consumption and IHD, with concordant directions. Unprocessed red meat and processed meat consumption was associated with higher IHD mortality overall and in men. Thirteen metabolites were associated with both unprocessed red meat and IHD mortality overall and showed a consistent direction, including triglycerides in different lipoproteins, phospholipids in very small very-low-density lipoprotein (VLDL), docosahexaenoic acid, tyrosine, creatinine, glucose, and glycoprotein acetyls. Ten metabolites related to triglycerides and VLDL were positively associated with both unprocessed red meat consumption and IHD mortality in men, but not in women. Processed meat consumption showed similar results with unprocessed red meat. Triglycerides in lipoproteins, fatty acids, and some nonlipid metabolites may play a role linking meat consumption to IHD. Triglycerides and VLDL-related lipid metabolism may contribute to the sex-specific associations. Sex differences should be considered in dietary recommendations.

Circulating citric acid cycle metabolites and risk of cardiovascular disease in the PREDIMED study

BACKGROUND AND AIM

Plasma citric acid cycle (CAC) metabolites might be likely related to cardiovascular disease (CVD). However, studies assessing the longitudinal associations between circulating CAC-related metabolites and CVD risk are lacking. The aim of this study was to evaluate the association of baseline and 1-year levels of plasma CAC-related metabolites with CVD incidence (a composite of myocardial infarction, stroke or cardiovascular death), and their interaction with Mediterranean diet interventions.

METHODS AND RESULTS

Case-cohort study from the PREDIMED trial involving participants aged 55-80 years at high cardiovascular risk, allocated to MedDiets or control diet. A subcohort of 791 participants was selected at baseline, and a total of 231 cases were identified after a median follow-up of 4.8 years. Nine plasma CAC-related metabolites (pyruvate, lactate, citrate, aconitate, isocitrate, 2-hydroxyglutarate, fumarate, malate and succinate) were measured using liquid chromatography-tandem mass spectrometry. Weighted Cox multiple regression was used to calculate hazard ratios (HRs). Baseline fasting plasma levels of 3 metabolites were associated with higher CVD risk, with HRs (for each standard deviation, 1-SD) of 1.46 (95%CI:1.20-1.78) for 2-hydroxyglutarate, 1.33 (95%CI:1.12-1.58) for fumarate and 1.47 (95%CI:1.21-1.78) for malate (p of linear trend <0.001 for all). A higher risk of CVD was also found for a 1-SD increment of a combined score of these 3 metabolites (HR = 1.60; 95%CI: 1.32-1.94, p trend <0.001). This result was replicated using plasma measurements after one-year. No interactions were detected with the nutritional intervention.

CONCLUSION

Plasma 2-hydroxyglutarate, fumarate and malate levels were prospectively associated with increased cardiovascular risk.

CLINICAL TRIAL NUMBER

ISRCTN35739639.

Advancing Stroke Research on Cerebral Thrombi with Omic Technologies

Cerebrovascular diseases represent a leading cause of disability, morbidity, and death worldwide. In the last decade, the advances in endovascular procedures have not only improved acute ischemic stroke care but also conceded a thorough analysis of patients' thrombi. Although early anatomopathological and immunohistochemical analyses have provided valuable insights into thrombus composition and its correlation with radiological features, response to reperfusion therapies, and stroke etiology, these results have been inconclusive so far. Recent studies applied single- or multi-omic approaches-such as proteomics, metabolomics, transcriptomics, or a combination of these-to investigate clot composition and stroke mechanisms, showing high predictive power. Particularly, one pilot studies showed that combined deep phenotyping of stroke thrombi may be superior to classic clinical predictors in defining stroke mechanisms. Small sample sizes, varying methodologies, and lack of adjustments for potential confounders still represent roadblocks to generalizing these findings. However, these techniques hold the potential to better investigate stroke-related thrombogenesis and select secondary prevention strategies, and to prompt the discovery of novel biomarkers and therapeutic targets. In this review, we summarize the most recent findings, overview current strengths and limitations, and present future perspectives in the field.

Genetic determinants of circulating metabolites and the risk of stroke and its subtypes

BACKGROUND AND PURPOSE

Circulating metabolites have been implicated in stroke pathogenesis, but their genetic determinants are understudied. Using a Mendelian randomization approach, our aim was to provide evidence for the relationship of circulating metabolites and the risk of stroke and its subtypes.

METHODS

Genetic instruments of 102 circulating metabolites were obtained from a genome-wide association study, including 24,925 European individuals. Stroke was extracted from the MEGASTROKE dataset (67,162 cases; 454,450 controls) and a lacunar stroke dataset (7338 cases; 254,798 controls). The magnetic resonance imaging markers of cerebral small vessel disease and microstructural injury were evaluated by a genome-wide association study of white matter hyperintensities (N = 18,381), fractional anisotropy (N = 17,663), mean diffusivity (N = 17,467) and brain microbleeds (N = 25,862). The inverse-variance weighted method Mendelian randomization was used as the primary analytical method, and directional pleiotropy and heterogeneity were examined in sensitivity analyses.

RESULTS

A genetic predisposition to a higher level of cholesterol in small and low-density lipoprotein (LDL) was associated with risk of stroke (odds ratio [OR] 1.14, 95% confidence interval [CI] 1.08-1.21, p = 5.98 × 10-7 ), especially for large-artery atherosclerotic stroke (OR 1.34, 95% CI 1.19-1.52, p = 1.90 × 10-6 ). Total lipids in LDL particles were also associated with risk of stroke. A genetically determined higher cholesterol level in high-density lipoprotein (HDL-C) was associated with risk of intracerebral haemorrhage (OR 1.74, 95% CI 1.23-2.45, p = 1.66 × 10-3 ). No statistically significant association was found between genetic predisposition to circulating metabolites and magnetic resonance imaging markers of cerebral small vessel disease and microstructural injury.

CONCLUSIONS

Genetically determined levels of lipids in small LDL were associated with the risk of stroke, suggesting that a therapeutic strategy targeting small LDL levels may be crucial for stroke prevention. HDL-C was positively associated with the risk of intracerebral haemorrhage.

The therapeutic potential of triptolide and celastrol in neurological diseases

Neurological diseases are complex diseases affecting the brain and spinal cord, with numerous etiologies and pathogenesis not yet fully elucidated. Tripterygium wilfordii Hook. F. (TWHF) is a traditional Chinese medicine with a long history of medicinal use in China and is widely used to treat autoimmune and inflammatory diseases such as systemic lupus erythematosus and rheumatoid arthritis. With the rapid development of modern technology, the two main bioactive components of TWHF, triptolide and celastrol, have been found to have anti-inflammatory, immunosuppressive and anti-tumor effects and can be used in the treatment of a variety of diseases, including neurological diseases. In this paper, we summarize the preclinical studies of triptolide and celastrol in neurological diseases such as neurodegenerative diseases, brain and spinal cord injury, and epilepsy. In addition, we review the mechanisms of action of triptolide and celastrol in neurological diseases, their toxicity, related derivatives, and nanotechnology-based carrier system.

Primary Prevention of Ischemic Stroke

Ischemic stroke is by far the most common type of cerebrovascular event and remains a major cause of death and disability globally. Despite advancements in acute stroke care, primary prevention is still the most cost-effective approach in reducing the burden of ischemic stroke. The two main strategies for primary stroke prevention include population-wide versus high-risk group interventions. Interventions such as increasing access to primary care, regulation of salt and sugar contents in processed foods, public education, and campaigns to control cerebrovascular risk factors are examples of population-wide interventions. High-risk group interventions, on the other hand, focus on recognition of individuals at risk and aim to modify risk factors in a timely and multifaceted manner. This article provides an overview on conventional modifiable risk factors for ischemic stroke and highlights the emerging risk factors and approaches for high-risk group identification and treatment.

Circulating serum metabolites as predictors of dementia: a machine learning approach in a 21-year follow-up of the Whitehall II cohort study

BACKGROUND

Age is the strongest risk factor for dementia and there is considerable interest in identifying scalable, blood-based biomarkers in predicting dementia. We examined the role of midlife serum metabolites using a machine learning approach and determined whether the selected metabolites improved prediction accuracy beyond the effect of age.

METHODS

Five thousand three hundred seventy-four participants from the Whitehall II study, mean age 55.8 (standard deviation (SD) 6.0) years in 1997-1999 when 233 metabolites were quantified using nuclear magnetic resonance metabolomics. Participants were followed for a median 21.0 (IQR 20.4, 21.7) years for clinically-diagnosed dementia (N=329). Elastic net penalized Cox regression with 100 repetitions of nested cross-validation was used to select models that improved prediction accuracy for incident dementia compared to an age-only model. Risk scores reflecting the frequency with which predictors appeared in the selected models were constructed, and their predictive accuracy was examined using Royston's R², Akaike's information criterion, sensitivity, specificity, C-statistic and calibration.

RESULTS

Sixteen of the 100 models had a better c-statistic compared to an age-only model and 15 metabolites were selected at least once in all 16 models with glucose present in all models. Five risk scores, reflecting the frequency of selection of metabolites, and a 1-SD increment in all five risk scores was associated with higher dementia risk (HR between 3.13 and 3.26). Three of these, constituted of 4, 5 and 15 metabolites, had better prediction accuracy (c-statistic from 0.788 to 0.796) compared to an age-only model (c-statistic 0.780), all p<0.05.

CONCLUSIONS

Although there was robust evidence for the role of glucose in dementia, metabolites measured in midlife made only a modest contribution to dementia prediction once age was taken into account.

Circulating metabolites associated with incident myocardial infarction and stroke: A prospective cohort study of 90 438 participants

The relevance between circulating metabolites and vascular events remains controversial and comprehensive studies are lacking. We sought to investigate the prospective associations of plasma metabolomics with risks of incident stroke, ischemic stroke (IS), hemorrhagic stroke (HS), and myocardial infarction (MI). Within the UK Biobank cohort, 249 circulating metabolites were measured in 90 438 participants without baseline vascular diseases. Cox proportional hazards regressions were applied to estimate adjusted hazard ratios (HRs) for per 1 standard deviation increment in metabolites. The least absolute shrinkage and selection operator algorithm was used for selecting metabolite subsets. During a median of 9.0 years of follow-up, we documented 833 incident stroke and 1256 MI cases. Lipid constituents, comprising cholesterol, cholesteryl esters, free cholesterol, phospholipids, and total lipids, in very low- (VLDL), intermediate- (IDL), and low-density lipoprotein (LDL) particles were positively associated with MI risk (HR = 1.12 to 1.36; 95% CI = 1.06 to 1.44), while in high-density lipoprotein (HDL) particles showed inverse associations (HR = 0.68 to 0.81; 95% CI = 0.63 to 0.87). Similar association pattern with MI was also observed for VLDL, IDL, LDL, and HDL particles themselves. In contrast, triglycerides within all lipoproteins, including most HDL particles, were positively associated with MI risk (HR = 1.14 to 1.28; 95% CI = 1.08 to 1.35) and, to a slightly lesser extent, with stroke and IS. Unsaturation of fatty acids and albumin were inversely associated with risks of stroke, IS, and MI. In contrast, the linear association for HS is absent. When combining multiple metabolites, the metabolite risk score captured a drastically elevated risk of all vascular events, about twice that of any single metabolite. Taken together, circulating metabolites showed remarkably widespread associations with incident MI, but substantially weakened associations with risks of stroke and its subtypes. Exhaustive metabolomics profiling may shed light on vascular risk prediction and, in turn, guide pertinent strategies of intervention and treatment.

Nucleosides Associated With Incident Ischemic Stroke in the REGARDS and JHS Cohorts

BACKGROUND AND OBJECTIVES

Both genetic and environmental factors contribute to stroke risk. We sought to identify novel metabolites associated with incident stroke in the Reasons for Geographic and Racial Differences in Stroke (REGARDS) cohort and determine whether they reflected genetic or environmental variation.

METHODS

This was a stroke case-cohort observational study nested in REGARDS. Cases were defined as incident stroke and metabolomic profiles were compared to a randomly selected control cohort. In baseline plasma samples, 162 metabolites were measured using liquid chromatography-tandem mass spectrometry. Cox proportional hazards models were adjusted for age, sex, race, and age by race in the base model. Fully adjusted models included traditional stroke risk factors. Mediation analyses conducted for these stroke risk factors used the metabolite as mediator. Genome-wide associations with the leading candidate metabolites were calculated using array data. Replication analyses in the Jackson Heart Study (JHS) were conducted using random effects meta-analysis.

RESULTS

There were 2,043 participants who were followed over an average period of 7.1 years, including 1,075 stroke cases and 968 random controls. Nine metabolites were associated with stroke in the base model, 8 of which were measured and remained significant in meta-analysis with JHS. In the fully adjusted model in REGARDS, guanosine (hazard ratio [HR] 1.34, 95% CI 1.18-1.53; p = 7.26 × 10-6) and pseudouridine (HR 1.28, 95% CI 1.13-1.45; p = 1.03 × 10-4) were associated with incident ischemic stroke following Bonferroni adjustment. Guanosine also partially mediated the relationship between hypertension and stroke (17.6%) and pseudouridine did not mediate any risk factor. Genome-wide association analysis identified loci rs34631560 and rs34631560 associated with pseudouridine, but these did not explain the association of pseudouridine with stroke.

DISCUSSION

Guanosine and pseudouridine are nucleosides associated with incident ischemic stroke independently of other risk factors. Genetic and mediation analyses suggest that environmental exposures rather than genetic variation link nucleoside levels to stroke risk.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that guanosine and pseudouridine are associated with incident stroke.

Metabolomic Profiles Associated With Incident Ischemic Stroke

BACKGROUND AND OBJECTIVES

Women have higher lifetime risk of stroke than men, and metabolic factors seem more strongly associated with stroke for women than men. However, few studies in either men or women have evaluated metabolomic profiles and incident stroke.

METHODS

We applied liquid chromatography-tandem mass spectrometry to measure 519 plasma metabolites in a discovery set of women in the Nurses' Health Study (NHS; 454 incident ischemic stroke cases, 454 controls) with validation in 2 independent, prospective cohorts: Prevención con Dieta Mediterránea (PREDIMED; 118 stroke cases, 791 controls) and Nurses' Health Study 2 (NHS2; 49 ischemic stroke cases, 49 controls). We applied logistic regression models with stroke as the outcome to adjust for multiple risk factors; the false discovery rate was controlled through the q value method.

RESULTS

Twenty-three metabolites were significantly associated with incident stroke in NHS after adjustment for traditional risk factors (q < 0.05). Of these, 14 metabolites were available in PREDIMED and 3 were significantly associated with incident stroke: methionine sulfoxide, N6-acetyllysine, and sucrose (q < 0.05). In NHS2, one of the 23 metabolites (glucuronate) was significantly associated with incident stroke (q < 0.05). For all 4 metabolites, higher levels were associated with increased risk. These 4 metabolites were used to create a stroke metabolite score (SMS) in the NHS and tested in PREDIMED. Per unit of standard deviation of SMS, the odds ratio for incident stroke was 4.12 (95% confidence interval [CI] 2.26-7.51) in PREDIMED, after adjustment for risk factors. In PREDIMED, the area under the receiver operating characteristic curve (AUC) for the model including SMS and traditional risk factors was 0.70 (95% CI 0.75-0.79) vs the AUC for the model including the traditional risk factors only of 0.65 (95% CI 0.70-0.75), corresponding to a 5% improvement in risk prediction with SMS (p < 0.005).

DISCUSSION

Metabolites associated with stroke included 2 amino acids, a carboxylic acid, and sucrose. A composite SMS including these metabolites was associated with ischemic stroke and showed improvement in risk prediction beyond traditional risk factors.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that a SMS accurately predicts incident ischemic stroke risk.

Integrated Analysis of the Cecal Microbiome and Plasma Metabolomics to Explore NaoMaiTong and Its Potential Role in Changing the Intestinal Flora and Their Metabolites in Ischemic Stroke

Ischemic stroke (IS), as a leading cause of disability worldwide, affects intestinal bacterial communities and their metabolites, while recent discoveries have highlighted the importance of the intestinal microflora in the development of IS. Systematic investigations of complex intestinal bacterial communities and their metabolites during ischemic brain injury contribute to elucidate the promising therapeutic targets for IS. However, the associations between intestinal microbiota and related circulating metabolic processes in IS remained unclear. Hence, to identify the changed microflora and their metabolites in IS of NaoMaiTong (NMT), an effective clinical medication, we established the middle cerebral artery occlusion/reperfusion (MCAO/R) model using conventionalized and pseudo-germ-free (PGF) rats. Subsequently, we systematically screen the microflora and related metabolites changing in IS via an integrated approach of cecal 16S rRNA sequencing combined with plasma metabolomics. We found that NMT relied on intestinal flora to improve stroke outcome in conventionalized rats while the protection of NMT was reduced in PGF rats. Total 35 differential bacterial genera and 26 differential microbial metabolites were regulated by NMT. Furthermore, L-asparagine and indoleacetaldehyde were significantly negatively correlated with Lachnospiraceae_UCG.001 and significantly positively correlated with Lachnoclostridium. Indoleacetaldehyde also presented a negative correlation with Lactobacillus and Bifidobacterium. 2-Hydroxybutyric acid was strongly negatively correlated with Ruminococcus, Lachnospiraceae_UCG.001 and Lachnospiraceae_UCG.006. Creatinine was strongly negatively correlated with Akkermansia. In summary, the research provided insights into the intricate interaction between intestinal microbiota and metabolism of NMT in IS. We identified above differential bacteria and differential endogenous metabolites which could be as prebiotic and probiotic substances that can influence prognosis in stroke and have potential to be used as novel therapeutic targets or exogenous drug supplements.

Celastrol Protects against Cerebral Ischemia/Reperfusion Injury in Mice by Inhibiting Glycolysis through Targeting HIF-1α/PDK1 Axis

Cerebral ischemia/reperfusion (I/R) injury is closely related to dysfunctional glucose metabolism. Celastrol is a bioactive compound that has been found to exhibit neuroprotective effects in cerebral ischemia, while whether it can protect against cerebral I/R injury by regulating glycolysis remains unclear. The goal of this study is to investigate the role of celastrol on cerebral I/R injury and its underlying mechanisms in transient middle cerebral artery occlusion (tMCAO) mice. Methods. To observe the protective effect of celastrol and select its optimal dosage for further study, neurological score, TTC staining, and HE staining were used to evaluate neurological function, cerebral infarct volume, and cortical cell damage, respectively. QRT-PCR and Western blot were used to detect the mRNA and protein expression of hypoxia inducible factor-1α (HIF-1α), pyruvate dehydrogenasekinase1 (PDK1), lactate dehydrogenase A (LDHA), glucose transporter1 (GLUT1), and hexokinase2 (HK2), respectively. The lactate production, ATP level, and glucose content were assessed by assay kits. Results. Our results indicated that celastrol dose-dependently improved neurological function and reduced cerebral infarct volume and cortical cell death of tMCAO mice, and its optimal dosage was 4.5 mg/kg. In addition, celastrol significantly blocked I/R-induced increase of LDHA, GLUT1, HK2, and lactate production as well as decrease of ATP level and glucose content. Moreover, celastrol inhibited the I/R-induced upregulation of HIF-1α and PDK1. Overexpression of HIF-1α by DMOG reversed the protective effect of celastrol on cerebral I/R injury and blocked celastrol-induced suppression of glycolysis. Conclusions. Taken together, these results suggested that celastrol protected against cerebral I/R injury through inhibiting glycolysis via the HIF-1α/PDK1 axis.

Uncovering the Role of Gut Microbiota in Amino Acid Metabolic Disturbances in Heart Failure Through Metagenomic Analysis

Aims: Circulating amino acid (AA) abnormalities serve as predictors of adverse outcomes in patients with heart failure (HF). However, the role of the gut microbiota in AA disturbances remains unknown. Thus, we investigated gut microbial functions and their associations with AA metabolic alterations in patients with HF. Methods and Results: We performed whole-genome shotgun sequencing of fecal samples and mass spectrometry-based profiling of AAs in patients with compensated HF. Plasma levels of total essential AAs (EAAs) and histidine were significantly lower in patients with HF than in control subjects. HF patients also displayed increased and decreased abundance of gut microbial genes involved in the degradation and biosynthesis, respectively, of EAAs, including branched-chain AAs (BCAAs) and histidine. Importantly, a significant positive correlation was observed between the abundance of microbial genes involved in BCAA biosynthesis and plasma BCAA levels in patients with HF, but not in controls. Moreover, network analysis revealed that the depletion of Eubacterium and Prevotella, which harbor genes for BCAA and histidine biosynthesis, contributed to decreased abundance of microbial genes involved in the biosynthesis of those EAAs in patients with HF. Conclusions: The present study demonstrated the relationship between gut microbiota and AA metabolic disturbances in patients with HF.

The Association of 9 Amino Acids With Cardiovascular Events in Finnish Men in a 12-Year Follow-up Study

BACKGROUND AND AIMS

To investigate the significance of 9 amino acids as risk factors for incident cardiovascular disease events in 9584 Finnish men.

MATERIALS AND METHODS

A total of 9584 men (age 57.4 ± 7.0 years, body mass index 27.2 ± 4.2 kg/m2) from the Metabolic Syndrome in Men study without cardiovascular disease and type 1 diabetes at baseline were included in this study. A total of 662 coronary artery disease (CAD) events, 394 ischemic stroke events, and 966 cardiovascular disease (CVD; CAD and stroke combined) events were recorded in a 12.3-year follow-up. Amino acids were measured using nuclear magnetic resonance platform.

RESULTS

In Cox regression analysis, phenylalanine and tyrosine were significantly associated with increased risk of CAD and CVD events, and phenylalanine with increased risk of ischemic stroke after the adjustment for confounding factors. Glutamine was significantly associated with decreased risk of stroke and CVD events and nominally with CAD events. Alanine was nominally associated with CAD events.

CONCLUSION

We identified alanine as a new amino acid associated with increased risk of CAD and glutamine as a new amino acid associated with decreased risk of ischemic stroke. We also confirmed that phenylalanine and tyrosine were associated with CAD, ischemic stroke, and CVD events.

Metabolomic Profiles of Men and Women Ischemic Stroke Patients

Background: Stroke is known to affect both men and women; however, incidence and outcomes differ between them. Therefore, the discovery of novel, sex-specific, blood-based biomarkers for acute ischemic stroke (AIS) patients has the potential to enhance the understanding of the etiology of this deadly disease in the content of sex. The objective of this study was to identify serum metabolites associated with male and female AIS patients. Methods: Metabolites were measured with the use of untargeted, reverse-phase ultra-performance liquid chromatography-tandem mass spectrometry quantification from blood specimens collected from AIS patients. Samples were collected from 36 patients comprising each of 18 men and women with matched controls. Metabolic pathway analysis and principal component analysis (PCA) was used to differentiate metabolite profiles for male and female AIS patients from the control, while logistic regression was used to determine differences in metabolites between male and female AIS patients. Results: In female AIS patients, 14 distinct altered metabolic pathways and 49 corresponding metabolites were identified, while 39 metabolites and 5 metabolic pathways were identified in male patients. Metabolites that are predictive of ischemic stroke in female patients were 1-(1-enyl-palmitoyl)-2-arachidonoyl-GPC (P-16:0/20:4) (AUC = 0.914, 0.765–1.000), 1-(1-enyl-palmitoyl)-2-palmitoyl-GPC (P-16:0/16:0) (AUC = 0.840, 0.656–1.000), and 5,6-dihydrouracil (P-16:0/20:2) (AUC = 0.815, 0.601–1.000). Significant metabolites that were predictive of stroke in male patients were 5alpha-androstan-3alpha,17beta-diol disulfate (AUC = 0.951, 0.857–1.000), alpha-hydroxyisocaproate (AUC = 0.938, 0.832–1.000), threonate (AUC = 0.877, 0.716–1.000), and bilirubin (AUC = 0.817, 0.746–1.000). Conclusions: In the current study, the untargeted serum metabolomics platform identified multiple pathways and metabolites associated with male and female AIS patients. Further research is necessary to characterize how these metabolites are associated with the pathophysiology in male and female AIS patients.

Metabolomics and metabolites in ischemic stroke

Stroke is a major reason for disability and the second highest cause of death in the world. When a patient is admitted to a hospital, it is necessary to identify the type of stroke, and the likelihood for development of a recurrent stroke, vascular dementia, and depression. These factors could be determined using different biomarkers. Metabolomics is a very promising strategy for identification of biomarkers. The advantage of metabolomics, in contrast to other analytical techniques, resides in providing low molecular weight metabolite profiles, rather than individual molecule profiles. Technically, this approach is based on mass spectrometry and nuclear magnetic resonance. Furthermore, variations in metabolite concentrations during brain ischemia could alter the principal neuronal functions. Different markers associated with ischemic stroke in the brain have been identified including those contributing to risk, acute onset, and severity of this pathology. In the brain, experimental studies using the ischemia/reperfusion model (IRI) have shown an impaired energy and amino acid metabolism and confirmed their principal roles. Literature data provide a good basis for identifying markers of ischemic stroke and hemorrhagic stroke and understanding metabolic mechanisms of these diseases. This opens an avenue for the successful use of identified markers along with metabolomics technologies to develop fast and reliable diagnostic tools for ischemic and hemorrhagic stroke.