Associations of plasma TMAO and its precursors with stroke risk in the general population: A nested case-control study

The Tryptophan Index Is Associated with Risk of Ischemic Stroke: A Community-Based Nested Case-Control Study

BACKGROUND

The relative availability of the essential amino acid tryptophan in the brain, as indicated by the tryptophan index, which is the ratio of tryptophan to its competing amino acids (CAAs) in circulation, has been related to major depression. However, it remains unknown whether tryptophan availability is involved in the pathogenesis of ischemic stroke.

AIMS

We aimed to investigate the relationship between the tryptophan index and the risk of ischemic stroke.

METHODS

We performed a nested case-control study within a community-based cohort in eastern China over the period 2013 to 2018. The analysis included 321 cases of ischemic stroke and 321 controls matched by sex and date of birth. The plasma levels of tryptophan and CAAs, including tyrosine, valine, phenylalanine, leucine, and isoleucine, were measured by ultra-high-performance liquid chromatography-tandem mass spectrometry. Conditional logistic regression analyses were employed to determine incidence rate ratios (IRRs) and their 95% confidence intervals (CIs).

RESULTS

After adjustment for body mass index, current smoking status, educational attainment, physical activity, family history of stroke, hypertension, diabetes, hyperlipidemia, and estimated glomerular filtration rate, an elevated tryptophan index was significantly associated with a reduced risk of ischemic stroke in a dose-response manner (IRR, 0.76; 95% CI, 0.63-0.93, per standard deviation increment). The plasma tryptophan or CAAs were not separately associated with the risk of ischemic stroke.

CONCLUSIONS

The tryptophan index was inversely associated with the risk of ischemic stroke. Our novel observations suggest that the availability of the essential amino acid tryptophan in the brain is involved in the pathogenesis of ischemic stroke.

Bibliometric analysis of the gut microbiota and stroke from 2002 to 2022

Stroke is the fifth leading cause of death worldwide, and the functional status of the gut plays a key role in patients' prognosis. Recent publications have explored the gut association with stroke, but few articles have been published that specifically address a comprehensive bibliometric analysis of the gut microbiota and its association with stroke. To address this gap, we used bibliometric methods to examine the landscape of research concerning the gut and stroke over approximately two decades, utilizing the Web of Science Core Collection (WoSCC). On November 1, 2022, a search was conducted for English-language articles published between 2002 and 2022, with only including original articles. Visual and statistical analyses were performed using CiteSpace, VOSviewer, and Bibliometrix 4.1.0 Package. After screening relevant articles, the results revealed that the number of articles published in this field has progressively increased during the last two decades. In particular, the total number of publications rapidly increased year by year from 2014. Among them, China ranked first in the world with a total of 227 publications. Authorship analysis highlighted Wang Z as the most prolific author, with 18 publications and an H-index of 14, highlighting significant contributions to this field. Meanwhile, the Southern Medical University of China was identified as the most productive institution. Moreover, analysis of keywords revealed that 'cerebral ischemia', 'intestinal microbiota', 'gut microbiota', and 'trimethylamine N-oxide' were popular topics searched, and research on the relationship between stroke and the gut continues to be a research hotspot. In summary, this study presents an overview of the progress and emerging trends in research on the relationship between stroke and gut health over the past two decades, providing a valuable resource for researchers aiming to understand the current state of the field and identify potential directions for future studies.

Dietary choline intake and health outcomes in U.S. adults: exploring the impact on cardiovascular disease, cancer prevalence, and all-cause mortality

BACKGROUND

Choline, an indispensable nutrient, plays a pivotal role in various physiological processes. The available evidence regarding the nexus between dietary choline intake and health outcomes, encompassing cardiovascular disease (CVD), cancer, and all-cause mortality, is limited and inconclusive. This study aimed to comprehensively explore the relationship between dietary choline intake and the aforementioned health outcomes in adults aged > 20 years in the U.S.

METHODS

This study utilized data from the National Health and Nutrition Examination Survey between 2011 and 2018. Dietary choline intake was evaluated using two 24-h dietary recall interviews. CVD and cancer status were determined through a combination of standardized medical status questionnaires and self-reported physician diagnoses. Mortality data were gathered from publicly available longitudinal Medicare and mortality records. The study utilized survey-weighted logistic and Cox regression analyses to explore the associations between choline consumption and health outcomes. Restricted cubic spline (RCS) analysis was used for dose‒response estimation and for testing for nonlinear associations.

RESULTS

In our study of 14,289 participants (mean age 48.08 years, 47.71% male), compared with those in the lowest quintile (Q1), the adjusted odds ratios (ORs) of CVD risk in the fourth (Q4) and fifth (Q5) quintiles of choline intake were 0.70 (95% CI 0.52, 0.95) and 0.65 (95% CI 0.47, 0.90), respectively (p for trend = 0.017). Each 100 mg increase in choline intake was associated with a 9% reduced risk of CVD. RCS analysis revealed a linear correlation between choline intake and CVD risk. Moderate choline intake (Q3) was associated with a reduced risk of mortality, with an HR of 0.75 (95% CI 0.60-0.94) compared with Q1. RCS analysis demonstrated a significant nonlinear association between choline intake and all-cause mortality (P for nonlinearity = 0.025). The overall cancer prevalence association was nonsignificant, except for colon cancer, where each 100 mg increase in choline intake indicated a 23% reduced risk.

CONCLUSION

Elevated choline intake demonstrates an inverse association with CVD and colon cancer, while moderate consumption exhibits a correlated reduction in mortality. Additional comprehensive investigations are warranted to elucidate the broader health implications of choline.

Trimethylamine N-oxide, β-alanine, tryptophan index, and vitamin B6-related dietary patterns in association with stroke risk

BACKGROUND AND AIMS

The aim of this study was to examine the associations of dietary patterns derived by reduced-rank regression (RRR) model reflecting variation in novel biomarkers (trimethylamine N-oxide, β-alanine, tryptophan index, and vitamin B6) with stroke risk.

METHODS AND RESULTS

We performed analyses based on a community-based cohort study "the Prospective Follow-up Study on Cardiovascular Morbidity and Mortality in China (PFS-CMMC)". Factor loadings were calculated by RRR using 11 food groups collected via a validated food frequency questionnaire and the four response variables based on its nested case-control data (393 cases of stroke vs. 393 matched controls). Dietary pattern scores were derived by applying the factor loadings to the food groups in the entire cohort (n = 15,518). The associations of dietary pattern with the stroke risk were assessed using Cox proportional hazards models. The dietary pattern characterized with higher intakes of red meat and poultry but lower intakes of fresh vegetables, fresh fruits, and fish/seafoods were identified for further analyses. The hazard ratios (HR) for the highest vs. lowest quartile was 1.55 [95 % confidence interval (CI): 1.18-2.03, P trend = 0.001] for total stroke, 2.96 [95 % CI: 1.53-5.71, P trend <0.001] for non-ischemic stroke, after adjustment for sex, age, educational attainment, current smoking, current drinking, body mass index, total energy intake, family history of stroke, hypertension, diabetes, hyperlipidemia, and estimated glomerular filtration rate.

CONCLUSION

Our findings highlight the importance of limited meat intake and increased intakes of fresh vegetables, fruits, and fish/seafoods in the prevention of stroke among Chinese adults.

Plasma levels of urea cycle related amino acids in association with risk of ischemic stroke: Findings from a nested case-control study

OBJECTIVES

The role of urea cycle related amino acids in the development of ischemic stroke (IS) remains unclear. The study aimed to evaluate the association of these amino acids with IS.

MATERIALS AND METHODS

We conducted a case-control study nested within a cohort study in Changshu, Eastern China. A total of 321 cases and 321 controls matched by age and gender were finally included. Plasma levels of ornithine, arginine, spermidine, and proline were measured using ultra-high performance liquid chromatography-tandem mass-spectrometry (UHPLC-MS/MS). Odds ratios (ORs) and their 95 % confidence intervals (CIs) were calculated by conditional logistic regression analyses.

RESULTS

Plasma ornithine was inversely associated with risk of IS [crude OR: 0.62 (95 % CI: 0.40-0.97)]. After adjustment for body mass index, smoking, hypertension, family history of stroke, estimated glomerular filtration rate, and total cholesterol, the corresponding ORs for the highest compared to the lowest quartiles was essentially unchanged [adjusted OR: 0.62 (95 % CI: 0.39-0.99)]. The risk association remained significant after repeating the analyses by excluding the first two years of follow-up. Plasma arginine, spermidine, and proline were not associated with the risk of IS.

CONCLUSION

We observed that higher plasma levels of ornithine were associated with a lower risk of incident IS. Our novel findings suggest a protective role of ornithine in the pathogenesis of IS.

Effect of TMAO on the incidence and prognosis of cerebral infarction: a systematic review and meta-analysis

Objective

This study aimed to evaluate the effect of trimethylamine oxide (TMAO) on the incidence and prognosis of cerebral infarction.

Methods

We searched PubMed, Embase, and Cochrane databases for all clinical studies on the association of TMAO with cerebral infarction incidence and prognosis from inception to April 2023. A systematic review and meta-analysis were conducted using the meta-analysis of observational studies in epidemiology (MOOSE) declaration list. The Newcastle-Ottawa Scale (NOS) was used to assess the quality of the study. This study protocol was registered on the PROSPERO database with the ID: CRD42023459661. The extracted data included the OR value of the effect of TMAO on the incidence and prognosis of cerebral infarction, the HR value between TMAO and underlying diseases, the RR value, 95% confidence intervals, and the AUC value of TMAO in the prediction model of cerebral infarction.

Results

Fifteen studies including 40,061 patients were included. All the patients were from China or Germany. The TMAO level was significantly correlated with the Modified Rankin Score (mRS) 3 months after the onset of cerebral infarction (OR, 1.581; 95% CI, 1.259-1.987; p < 0.01). The TMAO level was significantly correlated with the rate of first-time incidence and recurrence of cerebral infarction (OR, 1.208; 95% CI, 1.085-1.344; p < 0.01 and HR, 1.167; 95% CI, 1.076-1.265; p < 0.01, respectively). The TMAO level was also highly correlated with disease severity at onset (National Institutes of Health Stroke Scale, NIHSS >5) (OR, 5.194; 95% CI, 1.206-22.363; p < 0.05), but had no significant correlation with mortality after cerebral infarction (p > 0.05). Correlation analysis of TMAO with underlying diseases in the population indicated that TMAO had a significant correlation with histories of hypertension, diabetes mellitus, coronary artery disease, and cerebral infarction (p < 0.05), but not with hyperlipidemia (p > 0.05). Six risk prediction models of TMAO for cerebral infarction reported in four studies were systematically evaluated; five of them had good predictive value (AUC ≥ 0.7).

Conclusion

TMAO is an independent risk factor affecting the onset, prognosis, and severity of cerebral infarction.

Stroke and Vascular Cognitive Impairment: The Role of Intestinal Microbiota Metabolite TMAO

The gut microbiome interacts with the brain bidirectionally through the microbiome-gutbrain axis, which plays a key role in regulating various nervous system pathophysiological processes. Trimethylamine N-oxide (TMAO) is produced by choline metabolism through intestinal microorganisms, which can cross the blood-brain barrier to act on the central nervous system. Previous studies have shown that elevated plasma TMAO concentrations increase the risk of major adverse cardiovascular events, but there are few studies on TMAO in cerebrovascular disease and vascular cognitive impairment. This review summarized a decade of research on the impact of TMAO on stroke and related cognitive impairment, with particular attention to the effects on vascular cognitive disorders. We demonstrated that TMAO has a marked impact on the occurrence, development, and prognosis of stroke by regulating cholesterol metabolism, foam cell formation, platelet hyperresponsiveness and thrombosis, and promoting inflammation and oxidative stress. TMAO can also influence the cognitive impairment caused by Alzheimer's disease and Parkinson's disease via inducing abnormal aggregation of key proteins, affecting inflammation and thrombosis. However, although clinical studies have confirmed the association between the microbiome-gut-brain axis and vascular cognitive impairment (cerebral small vessel disease and post-stroke cognitive impairment), the molecular mechanism of TMAO has not been clarified, and TMAO precursors seem to play the opposite role in the process of poststroke cognitive impairment. In addition, several studies have also reported the possible neuroprotective effects of TMAO. Existing therapies for these diseases targeted to regulate intestinal flora and its metabolites have shown good efficacy. TMAO is probably a new target for early prediction and treatment of stroke and vascular cognitive impairment.

The association between trimethylamine N-oxide levels and ischemic stroke occurrence: a meta-analysis and Mendelian randomization study

BACKGROUND

Trimethylamine-N-oxide (TMAO), an intestinal microbiota-derived choline metabolite, has been found to be associated with ischemic stroke (IS) in more and more studies. However, the causal role of TMAO on IS occurrence remains perplexing.

METHODS

We comprehensively screened the related clinical studies on PubMed, Web of Science, and Embase. Case-control and cohort studies that reported the TMAO levels of both IS patients and healthy controls were included, and the risk of bias was assessed according to the criteria by the Centre for Evidence-Based Medicine in Oxford, UK. A meta-analysis of the retrieved publications was performed with a random-effect model to analyze the connection between TMAO levels and IS events. Besides, a Mendelian randomization (MR) analysis was performed to study the causal effect of TMAO on IS, with pooled data of TMAO and IS obtained from genome-wide association studies (GWAS). The following methods were used: MR-Egger, weighted median, inverse-variance weighted, simple mode, and weighted mode. The study has been registered in INPLASY (Registration number: INPLASY2023100027).

RESULTS

Eight cohort or case-control studies covering 2444 cases and 1707 controls were identified. The pooled data indicated that the IS patients tended to have higher TMAO levels compared with the controls (mean difference: 1.97 μM; 95% confidence interval [CI]: 0.87, 3.07; P = 0.0005), while distinctive heterogeneity (I2 = 96%, P < 0.00001) was observed. Sub-group analysis revealed that the heterogeneity of the studies might be derived from the studies themselves. However, no causal effect of TMAO on IS was observed (P > 0.05) in the Mendelian randomization analysis of this study.

CONCLUSION

We confirmed that IS patients tend to have higher TMAO levels than healthy individuals, while our findings of MR analysis did not support the causal role of TMAO in IS occurrence. Therefore, more studies are required for a better understanding of the relationship between TMAO levels and IS onset.

The relationship between trimethylamine-N-oxide and the risk of acute ischemic stroke: A dose‒response meta-analysis

BACKGROUND

Although trimethylamine-N-oxide (TMAO) shows a notable correlation with cardiovascular disease, its association with acute ischemic stroke (AIS) remains uncertain and necessitates further investigation.

OBJECTIVE

A meta-analysis was conducted to assess the relationship between trimethylamine-N-oxide and acute ischemic stroke.

METHODS

We conducted a comprehensive search in PubMed, Embase, Cochrane, CNKI, VIP, Wanfang, and CBM, spanning from their inception to 23 September 2023. The search was consistently updated and supplemented by bibliographies of retrieved articles and previous reviews. A total of 20 eligible studies, including 17 case‒controls and 3 cohort studies, were selected, involving 9141 participants (5283 case group, 3858 control group). For the dose‒response analysis, three case-control studies were eligible. We extracted and pooled TMAO mean and standard deviation from observational studies for control and ischemic stroke groups. The effect sizes were combined using the random-effects model. Where possible, dose‒response analysis was performed.

RESULT

Overall, the pooled standardized mean difference (SMD) demonstrated significantly higher concentrations of serum/plasma TMAO in AIS compared to the control group (SMD = 1.27; 95% CI: 0.9, 1.61, P<0.001). Additionally, the dose‒response meta-analysis revealed a 12.1% relative increase in the risk of acute ischemic stroke per 1 μmol/L rise in TMAO concentration (RR = 1.12; 95% CI 1.07-1.17; P<0.05; I2 = 1.6%, P = 0.4484).

CONCLUSION

These findings indicate a potential increased risk of AIS associated with elevated TMAO levels.

Plasma β-Alanine is Positively Associated With Risk of Ischemic Stroke: a Nested Case-Control Study

BACKGROUND

Previous studies suggested that β-alanine as a neurotransmitter could affect the pathogenesis of ischemic damage. However, the association between circulating β-alanine and risk of ischemic stroke (IS) has not been evaluated in populations.

OBJECTIVES

We aimed to examine the association between β-alanine and IS risk in a nested case-control study.

METHODS

We performed a case-control study nested within a prospective community-based cohort (n = 16457; median follow-up time: 5.3 y), which included 321 incident IS cases and 321 controls matched by age and sex. Β-alanine and other metabolites were measured in plasma after overnight fasting by LC-MS/MS. The association of β-alanine with risk of IS was evaluated by conditional logistic regression. BMI, current smoking, educational attainment, physical activity, total energy intake, family history of stroke, hypertension, diabetes, hyperlipidemia, and estimated GFR were adjusted in multivariable models.

RESULTS

There was a significant Spearman partial correlation between β-alanine and 4-pyridoxic acid (ρ = 0.239; P < 0.001). Participants with elevated β-alanine levels were more likely to develop IS with an adjusted OR of 1.26 (95% CI: 1.06-1.51; P = 0.011) (per standard deviation increment). This association remained significant after excluding the first 2 y of follow-up, and after further adjustment for red meat intake, total protein intake, medication use, or vitamin B6 indicators.

CONCLUSIONS

Our novel findings revealed that plasma β-alanine at baseline were positively associated with risk of IS and may function as an early biomarker of IS risk.