Relationship between elevated plasma trimethylamine N-oxide levels and increased stroke injury

Novel Insight into the Modulatory Effect of Traditional Chinese Medicine on Cerebral Ischemia-Reperfusion Injury by Targeting Gut Microbiota: A Review

Cerebral ischemia-reperfusion injury (CIRI) is clinically characterized by high rates of morbidity, disability, mortality, and recurrence as well as high economic burden. The clinical manifestations of CIRI are often accompanied by gastrointestinal symptoms such as intestinal bacterial dysbiosis and gastrointestinal bleeding. Gut microbiota plays an important role in the pathogenesis of CIRI, and its potential biological effects have received extensive attention. The gut microbiota not only affects intestinal barrier function but also regulates gastrointestinal immunity and host homeostasis. Traditional Chinese medicine (TCM), a multi-component and multi-targeted drug, has shown remarkable effects and few adverse reactions in the prevention and treatment of CIRI. Notably, the effect of TCM on CIRI by regulating gut microbiota and maintaining gastrointestinal homeostasis has gradually become a hot topic. This review summarizes the functional role of the gut microbiota in the development and progression of CIRI and the therapeutic effects of TCM on CIRI by improving gut microbiota dysbiosis, affecting gut microbiota metabolism, and maintaining host immunity. The active ingredients of TCM used for the treatment of CIRI in relevant studies were saponins, triterpenoids, phenolics, and alkaloids. In addition, the clinical effects of TCM used to treat CIRI were briefly discussed. This review established the clinical significance and development prospects of TCM-based CIRI treatments and provided the necessary theoretical support for the further development of TCM resources for the treatment of CIRI.

Microbiome-Derived Trimethylamine N-Oxide (TMAO) as a Multifaceted Biomarker in Cardiovascular Disease: Challenges and Opportunities

Biomarkers play a crucial role in various stages of disease management, including screening, diagnosis, prediction, prognosis, treatment, and safety monitoring. Although they are powerful tools in disease diagnosis, management, and drug development, identifying and validating reliable biomarkers remains a significant challenge. Among potential microbiome-derived biomarkers, trimethylamine N-oxide (TMAO) has gained notable attention for its link to atherosclerosis and cardiovascular risk. However, despite the growing body of research on TMAO, its practical application in clinical settings for disease management and patient outcome enhancement is still not a reality. This paper presents recent data on the utility of TMAO as a cardiovascular biomarker, categorized by its various roles: diagnostic, prognostic, susceptibility/risk, monitoring, pharmacodynamic/response, predictive, and safety. It also briefly discusses research on TMAO's potential role in cardiovascular disease development. While TMAO shows promise, particularly in prognostic applications, its reliability as a biomarker has been inconsistent across studies. These variances may result from several confounding factors that affect TMAO plasma levels, including diet, kidney function, and demographic variables. The review aims to elucidate the specific contexts in which TMAO can be valuable, potentially leading to more personalized and effective management of cardiovascular disease.

Gut Microbe-Generated Metabolite Trimethylamine-N-Oxide and Ischemic Stroke

Trimethylamine-N-oxide (TMAO) is a gut microbiota-derived metabolite, the production of which in vivo is mainly regulated by dietary choices, gut microbiota, and the hepatic enzyme flavin monooxygenase (FMO), while its elimination occurs via the kidneys. The TMAO level is positively correlated with the risk of developing cardiovascular diseases. Recent studies have found that TMAO plays an important role in the development of ischemic stroke. In this review, we describe the relationship between TMAO and ischemic stroke risk factors (hypertension, diabetes, atrial fibrillation, atherosclerosis, thrombosis, etc.), disease risk, severity, prognostic outcomes, and recurrence and discuss the possible mechanisms by which they interact. Importantly, TMAO induces atherosclerosis and thrombosis through lipid metabolism, foam cell formation, endothelial dysfunction (via inflammation, oxidative stress, and pyroptosis), enhanced platelet hyper-reactivity, and the upregulation and activation of vascular endothelial tissue factors. Although the pathogenic mechanisms underlying TMAO's aggravation of disease severity and its effects on post-stroke neurological recovery and recurrence risk remain unclear, they may involve inflammation, astrocyte function, and pro-inflammatory monocytes. In addition, this paper provides a summary and evaluation of relevant preclinical and clinical studies on interventions regarding the gut-microbiota-dependent TMAO level to provide evidence for the prevention and treatment of ischemic stroke through the gut microbe-TMAO pathway.

Trimethylamine N-Oxide Aggravates Neuro-Inflammation via lncRNA Fendrr/miR-145-5p/PXN Axis in Vascular Dementia Rats

Purpose

Vascular dementia (VaD) is the second most common dementia in the world. An increasing number of studies have demonstrated the important role of long non-coding RNAs (lncRNAs) in VaD. Our previous investigation demonstrated that Trimethylamine-N-oxide (TMAO) exacerbates cognitive impairment and neuropathological alterations in VaD rats. Thus, we hypothesized that TMAO could play an injury role in VaD by regulating lncRNAs.

Materials and Methods

The rats using the bilateral common carotid artery (2VO) model were administered TMAO (120 mg/kg) for 8 consecutive weeks, 4 weeks preoperatively and 4 weeks postoperatively. High-throughput sequencing was conducted to investigate the effects of TMAO treatment on lncRNA expression in rat hippocampus and bioinformatics analysis was performed to identify potential downstream targets. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was used to detect the levels of lncRNA fetal-lethal noncoding developmental regulatory RNA (Fendrr), miR-145-5p, and paxillin (PXN). Learning and spatial memory capacities were measured, as well as inflammatory factors. Nissl staining was used to observe neuronal injury in the CA1 area of the hippocampus. Furthermore, we used the Fendrr loss-of-function assay, miR-145-5p gain-of-function assays and PXN loss-of-function assay to explore the mechanisms by which TMAO acts on VaD.

Results

TMAO administration upregulated lncRNA Fendrr expression in the rat hippocampus, while the damaging effects of TMAO were counteracted after knockdown of Fendrr. Fendrr exhibits highly expressed in 2VO rats and sponged miR-145-5p, which targets PXN. Silencing of Fendrr or PXN, or promotion of miR-145-5p improved neurological function injury, reduced neuronal damage, as well as repressed inflammation response. Inhibition of miR-145-5p abrogated up Fendrr knockdown mediated influence on 2VO rats.

Conclusion

The results of this study indicated that TMAO inhibits the miR-145-5p/PXN axis by increasing the Fendrr expression, thus exacerbating the development of VaD.

Trimethylamine N-Oxide in Aquatic Foods

Trimethylamine N-oxide (TMAO), a characteristic nonprotein nitrogen compound, is widely present in seafood, which exhibits osmoregulatory effects for marine organisms in vivo and plays an important role in aquaculture and aquatic product preservation. However, much attention has been focused on the negative effect of TMAO since it has recently emerged as a putative promoter of chronic diseases. To get full knowledge and maximize our ability to balance the positive and negative aspects of TMAO, in this review, we comprehensively discuss the TMAO in aquatic products from the aspects of physiological functions for marine organisms, flavor, quality, the conversion of precursors, the influences on human health, and the seafood ingredients interaction consideration. Though the circulating TMAO level is inevitably enhanced after seafood consumption, dietary seafood still exhibits beneficial health effects and may provide nutraceuticals to balance the possible adverse effects of TMAO.

Trimethylamine-N-oxide and cerebral stroke risk: A review

Trimethylamine-N-oxide (TMAO) is a gut microbiota-derived metabolite produced by the action of gut microbiota and the hepatic enzyme Flavin Mono‑oxygenase 3 (FMO3). TMAO level has a positive correlation with the risk of cardiovascular events, including stroke, and their level is influenced mainly by dietary choice and the action of liver enzyme FMO3. TMAO plays a role in the development of atherosclerosis plaque, which is one of the causative factors of the stroke event. Preclinical and clinical investigations on the TMAO and associated stroke risk, severity, and outcomes are summarised in this review. In addition, mechanisms of TMAO-driven vascular dysfunction are also discussed, such as inflammation, oxidative stress, thrombus and foam cell formation, altered cholesterol and bile acid metabolism, etc. Post-stroke inflammatory cascades involving activation of immune cells, i.e., microglia and astrocytes, result in Blood-brain-barrier (BBB) disruption, allowing TMAO to infiltrate the brain and further aggravate inflammation. This event occurs as a result of the activation of the NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome pathway through the release of inflammatory cytokines and chemokines that further aggravate the BBB and initiate further recruitment of immune cells in the brain. Thus, it's likely that maintaining TMAO levels and associated gut microbiota could be a promising approach for treating and improving stroke complications.

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.

Gut Microbiota in Ischemic Stroke: Role of Gut Bacteria-Derived Metabolites

Ischemic stroke (IS) remains a leading cause of death and long-term disability globally. Several mechanisms including glutamate excitotoxicity, calcium overload, neuroinflammation, oxidative stress, mitochondrial damage, and apoptosis are known to be involved in the pathogenesis of IS, but the underlying pathophysiology mechanisms of IS are not fully clarified. During the past decade, gut microbiota were recognized as a key regulator to affect the health of the host either directly or via their metabolites. Recent studies indicate that gut bacterial dysbiosis is closely related to hypertension, diabetes, obesity, dyslipidemia, and metabolic syndrome, which are the main risk factors for cardiovascular diseases. Increasing evidence indicates that IS can lead to perturbation in gut microbiota and increased permeability of the gut mucosa, known as "leaky gut," resulting in endotoxemia and bacterial translocation. In turn, gut dysbiosis and impaired intestinal permeability can alter gut bacterial metabolite signaling profile from the gut to the brain. Microbiota-derived products and metabolites, such as short-chain fatty acids (SCFAs), bile acids (BAs), trimethylamine N-oxide (TMAO), lipopolysaccharides (LPS), and phenylacetylglutamine (PAGln) can exert beneficial or detrimental effects on various extraintestinal organs, including the brain, liver, and heart. These metabolites have been increasingly acknowledged as biomarkers and mediators of IS. However, the specific role of the gut bacterial metabolites in the context of stroke remains incompletely understood. In-depth studies on these products and metabolites may provide new insight for the development of novel therapeutics for IS.

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.

Trimethylamine N-oxide predicts stroke severity in diabetic patients with acute ischaemic stroke and is related to glycemic variability

BACKGROUND AND PURPOSE

The present study analyzed the relationship between circulating trimethylamine N-oxide (TMAO) levels and stroke severity in diabetic patients with acute ischaemic stroke. A further aim was to investigate whether higher TMAO levels were associated with platelet aggregation and glycemic variability.

METHODS

This was a cross-sectional analysis of 108 patients with type 2 diabetes mellitus (DM) undergoing acute ischaemic stroke and 60 healthy controls. Fasting plasma TMAO was measured using high-performance liquid chromatography with online electrospray ionization tandem mass spectrometry.

RESULTS

Plasma TMAO levels of patients with acute ischaemic stroke were significantly higher than those of healthy controls. Amongst stroke patients, 50 were defined as undergoing mild stroke, and their plasma TMAO levels were lower compared to those with moderate to severe stroke. Platelet aggregation and mean amplitude of glycemic excursions were both correlated with plasma TMAO levels and these relationships remained significant in multiple linear regression analyses. Moreover, in streptozotocin-induced diabetic rats fed a diet enriched with choline to increase TMAO synthesis, platelet aggregation was significantly increased in the DM + choline and fluctuating DM (FDM) + choline groups compared to the control group. This increase was abolished in rats receiving oral antibiotics, which markedly reduced plasma TMAO levels. Importantly, compared with the DM + choline group, the FDM + choline group displayed significantly elevated TMAO levels and higher platelet aggregation.

CONCLUSIONS

Our results demonstrated that higher plasma TMAO levels were associated with stroke severity and suggested a novel link between plasma TMAO levels and glycemic variability in diabetic patients with acute ischaemic stroke.

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 Trimethylamine-N-Oxide and Incident Ischemic Stroke: The Cardiovascular Health Study and the Multi-Ethnic Study of Atherosclerosis

Background The association of circulating trimethylamine-N-oxide (TMAO) with stroke has received limited attention. To address this gap, we examined the associations of serial measures of plasma TMAO with incident ischemic stroke. Methods and Results We used a prospective cohort design with data pooled from 2 cohorts. The settings were the CHS (Cardiovascular Health Study), a cohort of older adults, and the MESA (Multi-Ethnic Study of Atherosclerosis), both in the United States. We measured plasma concentrations of TMAO at baseline and again during the follow-up using high-performance liquid chromatography and mass spectrometry. We assessed the association of plasma TMAO with incident ischemic stroke using proportional hazards regression adjusted for risk factors. The combined cohorts included 11 785 participants without a history of stroke, on average 73 (CHS) and 62 (MESA) years old at baseline, including 60% (CHS) and 53% (MESA) women. We identified 1031 total incident ischemic strokes during a median 15-year follow-up in the combined cohorts. In multivariable analyses, TMAO was significantly associated with incident ischemic stroke risk (hazard ratios comparing a doubling of TMAO: 1.11 [1.03-1.18], P=0.004). The association was linear over the range of TMAO concentrations and appeared restricted to those without diagnosed coronary heart disease. An association with hemorrhagic stroke was not found. Conclusions Plasma TMAO levels are associated with incident ischemic stroke in a diverse population. Registration URL: https://www.clinicaltrials.gov. Unique identifier: NCT00005133.

Increased plasma levels of circPTP4A2 and circTLK2 are associated with stroke injury

OBJECTIVE

Accumulating studies have shown that circulating circular RNAs (circRNAs) represent novel biomarkers for many human diseases. We investigated whether plasma circPTP4A2 and circTLK2 levels are associated with stroke severity, infarct volume, stroke etiology, and functional outcome in acute ischemic stroke (AIS) patients.

METHODS

We applied quantitative real-time PCR (qPCR) to measure plasma circPTP4A2 and circTLK2 levels of 236 AIS patients within 72 h of symptoms onset and 136 healthy controls. We further assessed the National Institutes of Health Stroke Scale (NIHSS), infarct size, the Trial of Org 10172 in Acute Stroke Treatment (TOAST) classification and the 90-day modified Rankin scale (mRS) for each patient.

RESULTS

At admission, plasma circPTP4A2 and circTLK2 levels in patients with moderate to severe stroke were significantly higher compared to those with mild stroke. Logistic regression and receiver-operating characteristic (ROC) curve analyses indicated that they might function as predictive biomarkers for moderate to severe stroke. We also observed a medium positive correlation between these two circRNAs and NIHSS. Plasma circPTP4A2 and circTLK2 levels were slight positively correlated with cerebral infarct volume only in anterior circulation infarction (ACI) patients. Levels of both circPTP4A2 and circTLK2 were closely related with large artery atherosclerosis (LAA) stroke. Moreover, changes within 7 days after admission in circPTP4A2 and circTLK2 were able to predict unfavorable clinical outcome 90 days after AIS.

INTERPRETATION

These results demonstrate that plasma circPTP4A2 and circTLK2 strongly correlated with severity, subtypes and prognosis of AIS, and they could serve as promising biomarkers.

Trimethylamine N-Oxide and White Matter Hyperintensity Volume Among Patients With Acute Ischemic Stroke

Importance

Although increasing evidence suggests that trimethylamine N-oxide (TMAO) is associated with atherosclerosis, little is known about whether TMAO and its related metabolites (ie, choline, betaine, and carnitine) are associated with small vessel disease.

Objective

To evaluate the association between TMAO and its related metabolites with features of cerebral small vessel disease, including white matter hyperintensity volume (WMHV) and acute lacunar infarction.

Design, Setting, and Participants

This cross-sectional study included patients enrolled in the Specialized Programs of Translational Research in Acute Stroke biorepository. The registry included 522 patients with acute ischemic stroke who were 18 years or older who presented at the Massachusetts General Hospital or Brigham and Women's Hospital within 9 hours after onset between January 2007 and April 2010. The analyses in this study were conducted between November 2022 and April 2023.

Exposures

Plasma TMAO, choline, betaine, and carnitine were measured by liquid chromatography-tandem mass spectrometry.

Main Outcomes and Measures

WMHV was quantified by a semiautomated approach using signal intensity threshold with subsequent manual editing. Ischemic stroke subtype was classified using the Causative Classification System.

Results

Among 351 patients included in this study, the mean (SD) age was 69 (15) years; 209 patients (59.5%) were male and had a median (IQR) admission National Institute of Health Stroke Scale of 6 (3-13). The magnetic resonance imaging subgroup consisted of 291 patients with a mean (SD) age of 67 (15) years. Among these, the median (IQR) WMHV was 3.2 (1.31-8.4) cm3. TMAO was associated with WMHV after adjustment for age and sex (β, 0.15; 95% CI, 0.01-0.29; P < .001). TMAO remained significant in a multivariate analysis adjusted for age, sex, hypertension, diabetes, and smoking (β, 0.14; 95% CI, 0-0.29; P = .05). TMAO was associated with lacunar stroke but not other ischemic stroke subtypes in a model adjusted for age, sex, hypertension, diabetes, and smoking (OR, 1.67; 95% CI, 1.05-2.66; P = .03).

Conclusions and Relevance

In this observational study, TMAO was associated with cerebral small vessel disease determined by WMHV and acute lacunar infarction. The association was independent of traditional vascular risk factors.

The Prognostic Biomarkers of Plasma Trimethylamine N-Oxide and Short-Chain Fatty Acids for Recanalization Therapy in Acute Ischemic Stroke

Bidirectional communication of the microbiota-gut-brain axis is crucial in stroke. Recanalization therapy, namely intravenous thrombolysis (IVT) and endovascular thrombectomy (EVT), are recommended for eligible patients with acute ischemic stroke (AIS). It remains unclear whether gut microbiota metabolites, namely trimethylamine N-oxide (TMAO) and short-chain fatty acids (SCFAs), can predict the prognosis after recanalization therapy. This prospective study recruited patients with AIS receiving IVT, EVT, or both. The National Institutes of Health Stroke Scale (NIHSS) and modified Rankin scale (mRS) scores were used to assess the severity and functional outcomes of AIS, respectively. A functional outcome of mild-to-moderate disability was defined as a mRS score of 0-3 at discharge. Plasma TMAO and SCFA levels were measured through liquid chromatography with triple-quadrupole mass spectrometry. Fifty-six adults undergoing recanalization therapy for AIS were enrolled. Results showed that TMAO levels were not associated with stroke severity and functional outcomes, while isovalerate levels (one of the SCFAs) were negatively correlated with NIHSS scores at admission and discharge. In addition, high isovalerate levels were independently associated with a decreased likelihood of severe disability. The study concluded that an elevated plasma isovalerate level was correlated with mild stroke severity and disability after recanalization therapy for AIS.

New insight into gut microbiota and their metabolites in ischemic stroke: A promising therapeutic target

The gut-brain axis has been shown to play a vital role in the prognosis and recovery of ischemic stroke (IS), which is associated with gut microbiota dysfunction and changes in the gastrointestinal system and epithelial barrier integrity. In turn, gut microbiota and its derived metabolites can influence stroke outcomes. In this review, we first describe the relationship between IS (clinical and experimental IS) and the gut microbiota. Second, we summarize the role and specific mechanisms of microbiota-derived metabolites in IS. Further, we discuss the roles of natural medicines targeting the gut microbiota. Finally, the potential use of the gut microbiota and derived metabolites as a promising therapeutic opportunity for stroke prevention, diagnosis, and treatment is explored.

Association of admission neutrophil serine proteinases levels with the outcomes of acute ischemic stroke: a prospective cohort study

BACKGROUND

Neutrophil serine proteinases (NSPs), released by activated neutrophils, are key proteins involved in the pathophysiologic processes of stroke. NSPs are also implicated in the process and response of thrombolysis. This study aimed to analyze three NSPs (neutrophil elastase, cathepsin G, and proteinase 3) in relation to acute ischemic stroke (AIS) outcomes and in relation to the outcomes of patients treated with intravenous recombinant tissue plasminogen activator (IV-rtPA).

METHODS

Among 736 patients prospectively recruited at the stroke center from 2018 to 2019, 342 patients diagnosed with confirmed AIS were included. Plasma neutrophil elastase (NE), cathepsin G (CTSG), and proteinase 3 (PR3) concentrations were measured on admission. The primary endpoint was unfavorable outcome defined as modified Rankin Scale score 3-6 at 3 months, and the secondary endpoints were symptomatic intracerebral hemorrhage (sICH) within 48 h, and mortality within 3 months. In the subgroup of patients who received IV-rtPA, post-thrombolysis early neurological improvement (ENI) (defined as National Institutes of Health Stroke Scale score = 0 or decrease of ≥ 4 within 24 h after thrombolysis) was also included as the secondary endpoint. Univariate and multivariate logistic regression analyses were performed to evaluate the association between NSPs levels and AIS outcomes.

RESULTS

Higher NE and PR3 plasma levels were associated with the 3-month mortality and 3-month unfavorable outcome. Higher NE plasma levels were also associated with the risk of sICH after AIS. After adjusting for potential confounders, plasma NE level > 229.56 ng/mL (odds ratio [OR] = 4.478 [2.344-8.554]) and PR3 > 388.77 ng/mL (OR = 2.805 [1.504-5.231]) independently predicted the 3-month unfavorable outcome. Regarding rtPA treatment, patients with NE plasma concentration > 177.22 ng/mL (OR = 8.931 [2.330-34.238]) or PR3 > 388.77 ng/mL (OR = 4.275 [1.045-17.491]) were over 4 times more likely to suffer unfavorable outcomes after rtPA treatment. The addition of NE and PR3 to clinical predictors of unfavorable functional outcome after AIS and the outcome after rtPA treatment improved discrimination as well as reclassification (integrated discrimination improvement = 8.2% and 18.1%, continuous net reclassification improvement = 100.0% and 91.8%, respectively).

CONCLUSIONS

Plasma NE and PR3 are novel and independent predictors of 3-month functional outcomes after AIS. Plasma NE and PR3 also possess predictive value to identify patients with unfavorable outcomes after rtPA treatment. NE is probably an important mediator of the effects of neutrophils on stroke outcomes, which worth further investigation.

Development and Validation of a Novel Nomogram to Predict Hypoalbuminemia among Patients with Stroke in the Neurocritical Care Unit

This study aimed to investigate hypoalbuminemia-related factors in patients with stroke in the neurocritical care unit (NCU) and to establish a nomogram model for hypoalbuminemia prediction. Data from 902 patients hospitalized for stroke in the NCU who had normal albumin levels on admission from March 2018 to December 2020 were analyzed. Logistic regression was used to identify the risk factors associated with hypoalbuminemia. A novel nomogram prediction model for hypoalbuminemia was constructed, and it was validated in an independent set (n = 233). The nomogram incorporated seven risk factors, including age, high comorbidity, mechanical ventilation, feeding routes, total protein, high-sensitivity C-reactive protein, and fibrinogen levels, and its area under the curve for predicting hypoalbuminemia in the developmental set and validation set were 0.856 and 0.870, respectively. The novel nomogram facilitates risk prediction of hypoalbuminemia among patients with stroke in the NCU, which might be useful for selecting treatment strategies and management.

Trimethylamine-N-oxide is associated with cardiovascular mortality and vascular brain lesions in patients with atrial fibrillation

OBJECTIVE

Trimethylamine-N-oxide (TMAO) is a metabolite derived from the microbial processing of dietary phosphatidylcholine and carnitine and the subsequent hepatic oxidation. Due to its prothrombotic and inflammatory mechanisms, we aimed to assess its role in the prediction of adverse events in a susceptible population, namely patients with atrial fibrillation.

METHODS

Baseline TMAO plasma levels were measured by liquid chromatography-tandem mass spectrometry in 2379 subjects from the ongoing Swiss Atrial Fibrillation cohort. 1722 underwent brain MRI at baseline. Participants were prospectively followed for 4 years (Q1-Q3: 3.0-5.0) and stratified into baseline TMAO tertiles. Cox proportional hazards and linear and logistic mixed effect models were employed adjusting for risk factors.

RESULTS

Subjects in the highest TMAO tertile were older (75.4±8.1 vs 70.6±8.5 years, p<0.01), had poorer renal function (median glomerular filtration rate: 49.0 mL/min/1.73 m² (35.6-62.5) vs 67.3 mL/min/1.73 m² (57.8-78.9), p<0.01), were more likely to have diabetes (26.9% vs 9.1%, p<0.01) and had a higher prevalence of heart failure (37.9% vs 15.8%, p<0.01) compared with patients in the lowest tertile. Oral anticoagulants were taken by 89.1%, 94.0% and 88.2% of participants, respectively (from high to low tertiles). Cox models, adjusting for baseline covariates, showed increased total mortality (HR 1.65, 95% CI 1.17 to 2.32, p<0.01) as well as cardiovascular mortality (HR 1.86, 95% CI 1.21 to 2.88, p<0.01) in the highest compared with the lowest tertile. When present, subjects in the highest tertile had more voluminous, large, non-cortical and cortical infarcts on MRI (log-transformed volumes; exponentiated estimate 1.89, 95% CI 1.11 to 3.21, p=0.02) and a higher chance of small non-cortical infarcts (OR 1.61, 95% CI 1.16 to 2.22, p<0.01).

CONCLUSIONS

High levels of TMAO are associated with increased risk of cardiovascular mortality and cerebral infarction in patients with atrial fibrillation.

TRIAL REGISTRATION NUMBER

NCT02105844.

Gut-brain axis: Mechanisms and potential therapeutic strategies for ischemic stroke through immune functions

After an ischemic stroke (IS) occurs, immune cells begin traveling to the brain and immune system from the gut and gastrointestinal tract, where most of them typically reside. Because the majority of the body's macrophages and more than 70% of the total immune cell pool are typically found within the gut and gastrointestinal tract, inflammation and immune responses in the brain and immune organs require the mobilization of a large number of immune cells. The bidirectional communication pathway between the brain and gut is often referred to as the gut-brain axis. IS usually leads to intestinal motility disorders, dysbiosis of intestinal microbiota, and a leaky gut, which are often associated with poor prognosis in patients with IS. In recent years, several studies have suggested that intestinal inflammation and immune responses play key roles in the development of IS, and thus may become potential therapeutic targets that can drive new therapeutic strategies. However, research on gut inflammation and immune responses after stroke remains in its infancy. A better understanding of gut inflammation and immune responses after stroke may be important for developing effective therapies. This review discusses the immune-related mechanisms of the gut-brain axis after IS and compiles potential therapeutic targets to provide new ideas and strategies for the future effective treatment of IS.

The association between neutrophil counts and neutrophil-to-lymphocyte ratio and stress hyperglycemia in patients with acute ischemic stroke according to stroke etiology

BACKGROUND AND PURPOSE

Stress hyperglycemia ratio (SHR), which is used to assess stress hyperglycemia, is associated with the functional outcome of ischemic stroke (IS). IS can induce the inflammatory response. Neutrophil counts and neutrophil-to-lymphocyte ratio (NLR) as good and easily available inflammatory biomarkers, the relationship between neutrophil counts and NLR and SHR were poorly explored in IS. We aimed to systemically and comprehensively explore the correlation between various blood inflammation markers (mainly neutrophil counts and NLR) and SHR.

METHODS

Data from 487 patients with acute IS(AIS) in Xiangya Hospital were retrospectively reviewed. High/low SHR groups according to the median of SHR (≤1.02 versus >1.02). Binary logistic regression analysis was used to evaluate the correlation between neutrophil counts and NLR and high SHR group. Subgroup analyses were performed in the TOAST classification and functional prognosis.

RESULTS

The neutrophil counts and NLR were all clearly associated with SHR levels in different logistic analysis models. In the subgroup analysis of TOAST classification, the higher neutrophil counts and NLR were the independent risk factors for high SHR patients with large-artery atherosclerosis (LAA) (neutrophil: adjusted OR:2.047, 95% CI: 1.355-3.093, P=0.001; NLR: adjusted OR:1.315, 95% CI: 1.129-1.530, P<0.001). The higher neutrophil counts were the independent risk factor for high SHR patients with cardioembolism (CE) (adjusted OR:2.413, 95% CI: 1.081-5.383, P=0.031). ROC analysis showed that neutrophil counts was helpful for differentiating high SHR group with CE and low SHR group with CE (neutrophil: AUC =0.776, P=0.002). However, there were no difference in levels of neutrophil counts and NLR between patients with SVO and without SVO. The higher neutrophil counts and NLR independently associated with high SHR patients with mRS ≤2 at 90 days from symptom onset, (neutrophil: adjusted OR:2.284, 95% CI: 1.525-3.420, P<0.001; NLR: adjusted OR:1.377, 95% CI: 1.164-1.629, P<0.001), but not in patients with mRS >2.

CONCLUSIONS

This study found that the neutrophil counts and NLR are positively associated with SHR levels in AIS patients. In addition, the correlation between neutrophil counts and NLR and different SHR levels are diverse according to TOAST classification and functional prognosis.

Trimethylamine-N-oxide: a potential biomarker and therapeutic target in ischemic stroke

Ischemic stroke is by far the most common cerebrovascular disease and a major burden to the global economy and public health. Trimethylamine-N-oxide (TMAO), a small molecule compound produced by the metabolism of intestinal microorganisms, is reportedly associated with the risk of stroke, as well as the severity and prognosis of stroke; however, this conclusion remains contentious. This article reviews the production of TMAO, TMAO's relationship with different etiological types of ischemic stroke, and the possibility of reducing TMAO levels to improve the prognosis of ischemic stroke.

Neutrophilic noncoding RNAs predict outcomes of acute ischemic stroke patients treated with recombinant tissue plasminogen activator

There’s no evidence demonstrating the association between noncoding RNAs levels before IV recombinant tissue plasminogen activator (rtPA) administration and the outcomes of acute ischemic stroke (AIS). 145 AIS patients received rtPA treatment were recruited at the stroke center from 2018 to 2019, and 103 patients were included in this study. A panel of noncoding RNAs (miRNA-23a, miRNA-193a, miRNA-128, miRNA-99a, miRNA-let-7a, miRNA-494, miRNA-424, and lncRNA H19) were measured in the circulating neutrophils of AIS patients before rtPA treatment. Endpoints included excellent outcome (modified Rankin Scale score [mRS] 0–1) or poor outcome (mRS &gt; 1) at 3 months and symptomatic intracerebral hemorrhage (sICH) after rtPA treatment. Among the eight noncoding RNAs detected in circulating neutrophils of the 103 participants, miRNA-23a levels were associated with the stroke severity on admission and symptom progression at 24 h after rtPA treatment. A noncoding RNA score composed of miRNA-23a, miRNA-99a, and lncRNA H19 was screened to predict the functional outcome at 3 months and the incidence of sICH after rtPA treatment. In the logistic regression analysis, the noncoding RNA score ≥ −0.336 (OR = 2.862 [1.029–7.958], p = 0.044) was an independent predictor of the poor outcome at 3 months after adjustment of clinical variables, the addition of the noncoding RNA score to the clinical model improved the discrimination (IDI% = 4.68 [0.65–8.71], p = 0.020), as well as the net reclassification (NRI% = 33.04 [0.54–71.49], p = 0.016). The noncoding RNA score ≥ −0.336 (OR = 5.250 [1.096–25.135], p = 0.038) was also independently predicted the sICH, the addition of the noncoding RNA score to the clinical variables improved discrimination and reclassification as well. The noncoding RNA score was also associated with the infarct volume and symptom improvement at 7 days after rtPA treatment. In conclusion, a higher neutrophilic noncoding RNA score provides predictive value to identify AIS patients with worse outcomes after rtPA treatment. miRNA-23a, miRNA-99a, and lncRNA H19 are worth further investigation for their effects in thrombolysis after AIS.

Plasmatic trimethylamine N-oxide and its relation to stroke: A systematic review and dose-response meta-analysis

BACKGROUND

Elevated circulating concentrations of the gut metabolite, trimethylamine N-oxide (TMAO), were found in patients who experienced stroke. However, it has not been reported whether a high level of TMAO is associated with a significantly increased risk of stroke. This study aimed to review the available scientific evidence about the relationship between TMAO levels and the risk of stroke in a dose-response meta-analysis.

METHODS

The PubMed, Embase, Cochrane library, and China National Knowledge Infrastructure databases were searched for studies starting from September 1996 to December 2020. Nine studies including 4402 subjects were reviewed in this study.

RESULTS

The results of meta-analysis showed that high levels of circulating TMAO were associated with an increased risk of stroke in patients in the random-effects model (odds ratio [OR], 1.64; 95% confidence interval [CI], 1.12-2.41; P = 0.047). The OR for the prevalence of stroke increased by 48% per 5-μmol/L increment (OR, 1.05; 95% CI, 1.16-1.78; P < 0.001) and by 132% per 10-μmol/L increment (OR, 2.32; 95% CI, 1.38-3.86; P < 0.001) in circulating TMAO concentration according to the dose-response meta-analysis.

CONCLUSION

There was a significant association between higher plasma TMAO concentrations and the risk of stroke. Further in-depth studies are warranted to validate this interaction and explore potential mechanisms.

Gut microbiota-derived metabolite trimethylamine-N-oxide and multiple health outcomes: an umbrella review and updated meta-analysis

BACKGROUND

Trimethylamine-N-oxide (TMAO) is a gut microbiota-derived metabolite produced from dietary nutrients. Many studies have discovered that circulating TMAO concentrations are linked to a wide range of health outcomes.

OBJECTIVES

This study aimed to summarize health outcomes related to circulating TMAO concentrations.

METHODS

We searched the Embase, Medline, Web of Science, and Scopus databases from inception to 15 February, 2022 to identify and update meta-analyses examining the associations between TMAO and multiple health outcomes. For each health outcome, we estimated the summary effect size, 95% prediction CI, between-study heterogeneity, evidence of small-study effects, and evidence of excess-significance bias. These metrics were used to evaluate the evidence credibility of the identified associations.

RESULTS

This umbrella review identified 24 meta-analyses that investigated the association between circulating TMAO concentrations and health outcomes including all-cause mortality, cardiovascular diseases (CVDs), diabetes mellitus (DM), cancer, and renal function. We updated these meta-analyses by including a total of 82 individual studies on 18 unique health outcomes. Among them, 14 associations were nominally significant. After evidence credibility assessment, we found 6 (33%) associations (i.e., all-cause mortality, CVD mortality, major adverse cardiovascular events, hypertension, DM, and glomerular filtration rate) to present highly suggestive evidence.

CONCLUSIONS

TMAO might be a novel biomarker related to human health conditions including all-cause mortality, hypertension, CVD, DM, cancer, and kidney function. Further studies are needed to investigate whether circulating TMAO concentrations could be an intervention target for chronic disease.This review was registered at www.crd.york.ac.uk/prospero/ as CRD42021284730.

Diet-Induced High Serum Levels of Trimethylamine-N-oxide Enhance the Cellular Inflammatory Response without Exacerbating Acute Intracerebral Hemorrhage Injury in Mice

Trimethylamine-N-oxide (TMAO), an intestinal flora metabolite of choline, may aggravate atherosclerosis by inducing a chronic inflammatory response and thereby promoting the occurrence of cerebrovascular diseases. Knowledge about the influence of TMAO-related inflammatory response on the pathological process of acute stroke is limited. This study was designed to explore the effects of TMAO on neuroinflammation, brain injury severity, and long-term neurologic function in mice with acute intracerebral hemorrhage (ICH). We fed mice with either a regular chow diet or a chow diet supplemented with 1.2% choline pre- and post-ICH. In this study, we measured serum levels of TMAO with ultrahigh-performance liquid chromatography-tandem mass spectrometry at 24 h and 72 h post-ICH. The expression level of P38-mitogen-protein kinase (P38-MAPK), myeloid differentiation factor 88 (MyD88), high-mobility group box1 protein (HMGB1), and interleukin-1β (IL-1β) around hematoma was examined by western blotting at 24 h. Microglial and astrocyte activation and neutrophil infiltration were examined at 72 h. The lesion was examined on days 3 and 28. Neurologic deficits were examined for 28 days. A long-term choline diet significantly increased serum levels of TMAO compared with a regular diet at 24 h and 72 h after sham operation or ICH. Choline diet-induced high serum levels of TMAO did not enhance the expression of P38-MAPK, MyD88, HMGB1, or IL-1β at 24 h. However, it did increase the number of activated microglia and astrocytes around the hematoma at 72 h. Contrary to our expectations, it did not aggravate acute or long-term histologic damage or neurologic deficits after ICH. In summary, choline diet-induced high serum levels of TMAO increased the cellular inflammatory response probably by activating microglia and astrocytes. However, it did not aggravate brain injury or worsen long-term neurologic deficits. Although TMAO might be a potential risk factor for cerebrovascular diseases, this exploratory study did not support that TMAO is a promising target for ICH therapy.

Phenylacetylglutamine, a Novel Biomarker in Acute Ischemic Stroke

Background: To discover novel metabolic biomarkers of ischemic stroke (IS), we carried out a two-stage metabolomic profiling of IS patients and healthy controls using untargeted and targeted metabolomic approaches.

Methods: We applied untargeted liquid chromatography-mass spectrometry (LC-MS) to detect the plasma metabolomic profiles of 150 acute IS patients and 50 healthy controls. The candidate differential microbiota-derived metabolite phenylacetylglutamine (PAGln) was validated in 751 patients with IS and 200 healthy controls. We evaluated the associations between PAGln levels and the severity and functional outcomes of patients with IS. Clinical mild stroke was defined as the National Institutes of Health Stroke Scale (NIHSS) score 0–5, and moderate-severe stroke as NIHSS score >5. A favorable outcome at 3 months after IS was defined as the modified Rankin Scale (mRS) score 0–2, and unfavorable outcome as mRS score 3–6.

Results: In untargeted metabolomic analysis, we detected 120 differential metabolites between patients with IS and healthy controls. Significantly altered metabolic pathways were purine metabolism, TCA cycle, steroid hormone biosynthesis, and pantothenate and CoA biosynthesis. Elevated plasma PAGln levels in IS patients, compared with healthy controls, were observed in untargeted LC-MS analysis and confirmed by targeted quantification (median 2.0 vs. 1.0 μmol/L; p < 0.001). Patients with moderate-severe stroke symptoms and unfavorable short-term outcomes also had higher levels of PAGln both in discovery and validation stage. After adjusting for potential confounders, high PAGln levels were independently associated with IS (OR = 3.183, 95% CI 1.671–6.066 for the middle tertile and OR = 9.362, 95% CI 3.797–23.083 for the highest tertile, compared with the lowest tertile) and the risk of unfavorable short-term outcomes (OR = 2.286, 95% CI 1.188–4.401 for the highest tertile).

Conclusions: IS patients had higher plasma levels of PAGln than healthy controls. PAGln might be a potential biomarker for IS and unfavorable functional outcomes in patients with IS.

Non-alcoholic fatty liver disease as an independent factor of cardiometabolic risk of cardiovascular diseases

Non-alcoholic fatty liver disease (NAFLD) is a pressing public health problem affecting up to a third of the world's adult population. The main reasons for its high mortality rate are cardiovascular diseases. They are caused by subclinical atherosclerosis characteristic of NAFLD, venous thromboembolic complications, functional and structural myocardial disorders, calcification of heart valves, heart rhythm and conduction disturbances. At the same time, NAFLD can serve as an independent factor of the cardiometabolic risk of their development, which is associated with atherogenic dyslipidemia, as well as the release of numerous pro-inflammatory mediators both from the pathologically altered liver and as a result of systemic endotoxemia, which is the result of disturbance of the intestinal microbiota, accompanied by a decrease in intestinal microbial gene richness., a change in its composition and function, followed by bacterial translocation. Considering that most patients with NAFLD die from cardiovascular complications, it becomes obvious that exclusively “liver-oriented” principles of their treatment cannot be sufficient, but require a multidisciplinary team approach involving cardiologists, cardiac surgeons and doctors of other related specialties.

The Gut Microbial-Derived Metabolite Trimethylamine N-Oxide and Atrial Fibrillation: Relationships, Mechanisms, and Therapeutic Strategies

Accumulating evidence has demonstrated that gut microbial-derived metabolite trimethylamine N-oxide (TMAO) plays a crucial role in the pathogenesis of many diseases and can be served as a prognostic biomarker for several cardiovascular disorders, including arrhythmia. Recently, some studies have documented that TMAO was associated with the occurrence, progression, recurrence, and embolism risk of atrial fibrillation (AF). The activation of related inflammatory signal pathways and the cardiac sympathetic nervous system (CSNS) caused by elevated TAMO may be the underlying mechanism. It is worth noting that intervention in the metabolic pathway of TMAO may be an underlying therapeutic target of AF. In addition, standardized and individualized treatment strategies in clinical practice may be of great significance for AF patients, particularly those with high serum TMAO concentrations. However, there are also contradictions in the current research on TMAO and AF. Moreover, notwithstanding the positive preclinical and clinical findings, data supporting a direct association between TMAO and AF is a paucity. Thus, conclusive evidence from preclinical studies and multi-center randomized controlled trials to reveal the essential relationship between TMAO and AF is needy. In this review, we have attempted to summarize recent studies on TMAO and AF, highlighted the potential therapeutic strategies for AF patients, followed by a discussion on directions for future research in this field.

Trimethylamine N-Oxide and Stroke Recurrence Depends on Ischemic Stroke Subtypes

BACKGROUND AND PURPOSE

Trimethylamine N-oxide (TMAO) has been recognized as a risk factor for cardiovascular disease. However, the role of TMAO in ischemic stroke remains unclear. As we know, ischemic stroke is a heterogeneous disease with variable pathogenesis. Hence, we aimed to investigate the association between TMAO and stroke recurrence according to etiology subtypes.

METHODS

A total of 10 756 ischemic stroke/transient ischemic attack patients from the Third China National Stroke Registry were enrolled, and 1-year follow-up data for stroke recurrence were analyzed. TOAST (Trial of ORG 10172 in Acute Stroke Treatment) criteria was used to classify the etiology subtypes. Plasma TMAO levels were quantified by liquid chromatography-mass spectrometry. The association between TMAO and stroke outcomes was analyzed using Cox regression models. We also conducted a meta-analysis on the association of TMAO levels and stroke risk.

RESULTS

Elevated TMAO level was independently associated with the risk of stroke recurrence (Q4 versus Q1: adjusted hazard ratio, 1.37 [95% CI, 1.15-1.64]) in multivariate Cox regression model. After stratification by TOAST subtypes, there was a significant association between TMAO and stroke recurrence in small artery occlusion subtype (adjusted hazard ratio, 1.43 [95% CI, 1.03-2.00]) but not in the others subtype (large-artery atherosclerosis, 1.19 [0.95-1.48]; cardioembolism, 1.54 [0.95-2.48]; others, 1.19 [0.98-1.44]). The meta-analysis reported on stroke recurrence for the highest versus lowest TMAO levels with a pooled hazard ratio of 1.66 (95% CI, 0.91-3.01) and similarly found an increased risk of stroke recurrence.

CONCLUSIONS

Elevated TMAO level is associated with increased risk of stroke recurrence in patients with small artery occlusion subtype, but this association seems to be attenuated in large-artery atherosclerosis, cardioembolism, and others subtypes.

Associations between Upper Extremity Motor Function and Aphasia after Stroke: A Multicenter Cross-Sectional Study

METHODS

Patients with stroke were compared and correlated from overall and three periods (1-3 months, 4-6 months, and >6 months). Fugl-Meyer assessment for the upper extremity (FMA-UE) and action research and arm test (ARAT) were used to compare the UE motor status between patients with PSA and without PSA through a cross-sectional study among 435 patients. Then, the correlations between the evaluation scale scores of UE motor status and language function of patients with PSA were analyzed in various dimensions, and the language subfunction most closely related to UE motor function was analyzed by multiple linear regression analysis.

RESULTS

We found that the scores of FMA-UE and ARAT in patients with PSA were 14 points ((CI) 10 to 18, p < 0.001) and 11 points lower ((CI) 8 to 13, p < 0.001), respectively, than those without PSA. Their FMA-UE (r = 0.70, p < 0.001) and ARAT (r = 0.62, p < 0.001) scores were positively correlated with language function. Regression analysis demonstrated that spontaneous speech ability may account for UE motor function (R 2 = 0.51, p < 0.001; R 2 = 0.42, p < 0.001). Consistent results were also obtained from the analyses within the three time subgroups.

CONCLUSION

Stroke patients with PSA have worse UE motor performance. UE motor status and language function showed positive correlations, in which spontaneous speech ability significantly accounts for the associations.

CCL2 (C-C Motif Chemokine Ligand 2) Biomarker Responses in Central Versus Peripheral Compartments After Focal Cerebral Ischemia

Background and Purpose

Inflammatory mediators in blood have been proposed as potential biomarkers in stroke. However, a direct relationship between these circulating factors and brain-specific ischemic injury remains to be fully defined.

Methods

An unbiased screen in a nonhuman primate model of stroke was used to find out the most responsive circulating biomarker flowing ischemic stroke. Then this phenomenon was checked in human beings and mice. Finally, we observed the temporospatial responsive characteristics of this biomarker after ischemic brain injury in mice to evaluate the direct relationship between this circulating factor and central nervous system–specific ischemic injury.

Results

In a nonhuman primate model, an unbiased screen revealed CCL2 (C-C motif chemokine ligand 2) as a major response factor in plasma after stroke. In mouse models of focal cerebral ischemia, plasma levels of CCL2 showed a transient response, that is, rapidly elevated by 2 to 3 hours postischemia but then renormalized back to baseline levels by 24 hours. However, a different CCL2 temporal profile was observed in whole brain homogenate, cerebrospinal fluid, and isolated brain microvessels, with a progressive increase over 24 hours, demonstrating a mismatch between brain versus plasma responses. In contrast to the lack of correlation with central nervous system responses, 2 peripheral compartments showed transient profiles that matched circulating plasma signatures. CCL2 protein in lymph nodes and adipose tissue was significantly increased at 2 hours and renormalized by 24 hours.

Conclusions

These findings may provide a cautionary tale for biomarker pursuits in plasma. Besides a direct central nervous system response, peripheral organs may also contribute to blood signatures in complex and indirect ways.

Trimethylamine oxide and its possible role in the development and progression of cardiovascular disease

Cardiovascular diseases continue to be the leading cause of death throughout the world and in Russia. Therefore, new possible risk factors for their development and progression are being studied. To date, information have been accumulated on unfavorable prognostic effect of elevated trimethylamine oxide (TMAO) levels on cardiovascular events, and the possible role of phospholipids (PLs) is being discussed. The aim of this review was to analyze the literature data on the potential relationship of TMAO and PLs with cardiovascular risk (CVR), as well as possible solutions to this problem. The search and analysis of publications was performed using Elibrary, PubMed, Medline, and Google Scholar databases in the period from their creation to 2021. It was found that high TMAO concentrations can have pro-inflammatory effects, stimulate atherogenesis and increase platelet aggregation. An increase in the blood TMAO levels increases the risk of cardiovascular events in patients with coronary artery disease, is associated with an increased risk of cardiovascular and all-cause death in patients with peripheral arterial disease and heart failure, and correlates with the extent of brain regions involved in stroke. The most important part in TMAO formation is taken by the gut microbiota, which metabolizes substrates, including PLs, to trimethylamine, which, when absorbed, is converted into TMAO in the liver. The analysis of available studies shows that the excessive intake of PLs into the gastrointestinal tract and the increased TMAO production are potentially interrelated with an increase in CVR. At the same time, PLs are currently used as drugs, in particular, as hepatoprotective agents. In view of this, large-scale randomized clinical trials are needed to study the CVR profile in patients receiving such therapy. Currently, other hepatoprotective agents are available that are devoid of such potential risks, since they do not contain PLs. One of these agents is ursodeoxycholic acid, which has proven its effectiveness and safety, including in patients with high CVR in routine clinical practice.

Brain to periphery in acute ischemic stroke: Mechanisms and clinical significance

The social and public health burdens of ischemic stroke have been increasing worldwide. In addition to focal brain damage, acute ischemic stroke (AIS) provokes systemic abnormalities across peripheral organs. AIS profoundly alters the autonomic nervous system, hypothalamic-pituitary-adrenal axis, and immune system, which further yield deleterious organ-specific consequences. Poststroke systemic pathological alterations in turn considerably contribute to the progression of ischemic brain injury, which accounts for the substantial impact of systemic complications on stroke outcomes. This review provides a comprehensive and updated pathophysiological model elucidating the systemic effects of AIS. To address their clinical significance and inform stroke management, we also outline the resulting systemic complications at particular stages of AIS and highlight the mechanisms. Future therapeutic strategies should attempt to integrate the treatment of primary brain lesions with interventions for secondary systemic complications, and should be tailored to patient individualized characteristics to optimize stroke outcomes.

Increased serum interleukin-34 levels as a novel diagnostic and prognostic biomarker in patients with acute ischemic stroke

BACKGROUND

Recent data reveal that interleukin-34 (IL-34) can drive inflammatory response, thereby participating in the pathogenesis of inflammatory diseases. However, the potential effect of IL-34 in acute ischemic stroke (AIS) remains unknown. The purpose of this study was to explore whether the levels of serum IL-34 were correlated with clinical severity or prognosis in AIS patients.

METHODS

In this prospective cohort study, serum IL-34 levels were detected in 150 healthy controls and 155 AIS patients. Univariate and multivariate logistic regression analysis were conducted to investigate the effect of IL-34 on the diagnosis and prognosis of AIS. ROC curve was utilized to evaluate predictive values for IL-34.

RESULTS

Serum IL-34 levels at admission were significantly higher in AIS patients than those in the healthy controls. Univariate and multivariate logistics regression analysis showed that IL-34 was an independent predictor of occurrence and functional outcome of AIS. The ROC curve demonstrated that IL-34 had a good predictive effect on the diagnosis and prognosis of AIS.

CONCLUSIONS

IL-34 can be used as a novel and independent diagnostic and predicting prognostic biomarker in AIS.

The Relationship of Large-Artery Atherothrombotic Stroke with Plasma Trimethylamine N-Oxide Level and Blood Lipid-Related Indices: A Cross-Sectional Comparative Study

Objective

The role of trimethylamine N-oxide (TMAO) in cardiovascular diseases has been highlighted. Nevertheless, the associations of large-artery atherosclerotic (LAA) stroke with TMAO and blood lipid-related indices are little investigated.

Methods

A cross-sectional comparative study was performed on 50 patients with LAA stroke and 50 healthy controls. Basic demographic data, common vascular risk factors, and blood lipid-related indices were collected. Plasma TMAO was detected through liquid chromatography tandem mass spectrometry. Multivariable unconditional logistic regression analyses were run to assess the associations of LAA stroke with plasma TMAO level and blood lipid-related indices. The area under the curve (AUC) of the receiver operating characteristic (ROC) was computed to assess the diagnostic performance of plasma TMAO level and blood lipid-related indices for LAA stroke.

Results

Compared with healthy controls, the elevated plasma TMAO level (odds ratio [OR], 7.03; 95% confidence interval [CI], 2.86, 17.25; p < 0.01) and Apo-B (OR, 1.74; 95% CI, 1.06, 2.85; p = 0.03) were observed in LAA stroke patients, while lower Apo-A1 (OR, 0.56; 95% CI, 0.34, 0.91; p = 0.02), Apo-A1 to Apo-B ratio (OR, 0.29; 95% CI, 0.15, 0.56; p < 0.01), and HDL-C (OR, 0.56; 95% CI, 0.35, 0.91; p = 0.02) were found in LAA stroke patients after adjusted for age and gender. Moreover, plasma TMAO (AUC, 0.89; 95% CI, 0.83, 0.95), Apo-A1 (AUC, 0.81; 95% CI, 0.72, 0.89), Apo-B (AUC, 0.81; 95% CI, 0.73, 0.90), Apo-A1 to Apo-B ratio (AUC, 0.85; 95% CI, 0.78, 0.93), and HDL-C (AUC, 0.81; 95% CI, 0.72, 0.89) showed good diagnostic values for LAA stroke in adjusted models.

Conclusions

The plasma TMAO level, Apo-A1, Apo-B, and HDL-C are important biomarkers for LAA stroke patients.

Nomogram to Predict Cognitive Dysfunction After a Minor Ischemic Stroke in Hospitalized-Population

An easily scoring system to predict the risk of cognitive impairment after minor ischemic stroke has not been available. We aimed to develop and externally validate a nomogram for predicting the probability of post-stroke cognitive impairment (PSCI) among hospitalized population with minor stroke. Moreover, the association of Trimethylamine N-oxide (TMAO) with PSCI is also investigated. We prospectively conducted a developed cohort on collected data in stroke center from June 2017 to February 2018, as well as an external validation cohort between June 2018 and February 2019. The main outcome is cognitive impairment defined as <22 Montreal Cognition Assessment (MoCA) score points 6 – 12 months following a minor stroke onset. Based on multivariate logistic models, the nomogram model was generated. Plasma TMAO levels were assessed at admission using liquid chromatography tandem mass spectrometry. A total of 228 participants completed the follow-up data for generating the nomogram. After multivariate logistic regression, seven variables remained independent predictors of PSCI to compose the nomogram included age, female, Fazekas score, educational level, number of intracranial atherosclerotic stenosis (ICAS), HbA1c, and cortical infarction. The area under the receiver-operating characteristic (AUC-ROC) curve of model was 0.829, C index was good (0.810), and the AUC-ROC of the model applied in validation cohort was 0.812. Plasma TMAO levels were higher in patients with cognitive impairment than in them without cognitive dysfunction (median 4.56 vs. 3.22 μmol/L; p ≤ 0.001). In conclusion, this scoring system is the first nomogram developed and validated in a stroke center cohort for individualized prediction of cognitive impairment after minor stroke. Higher plasma TMAO level at admission suggests a potential marker of PSCI.

Association of Trimethylamine N-Oxide and Its Precursor With Cerebral Small Vessel Imaging Markers

Background: High plasma levels of trimethylamine N-oxide (TMAO) and its precursor choline have been linked to stroke; however, their association with cerebral small vessel disease remains unclear. Here we evaluated the association of plasma levels of TMAO and choline with imaging markers of cerebral small vessel disease, including white matter hyperintensities, lacunes, and cerebral microbleeds.

Methods: We performed a baseline cross-sectional analysis of a multicenter hospital-based cohort study from 2015 to 2018. The data were collected from 30 hospitals in China and included 1,098 patients with ischemic stroke/transient ischemic attack aged ≥18 years. White matter hyperintensities, lacunes, and cerebral microbleeds were evaluated with the patients' demographic, clinical, and laboratory information removed. White matter hyperintensities were rated using the Fazekas visual grading scale, while the degree of severity of the lacunes and cerebral microbleeds was defined by the number of lesions.

Results: Increased TMAO levels were associated with severe white matter hyperintensities [adjusted odds ratio (aOR) for the highest vs. lowest quartile, 1.5; 95% confidence interval (CI), 1.0–2.1, p = 0.04]. High TMAO levels were more strongly associated with severe periventricular white matter hyperintensities (aOR for the highest vs. lowest quartile, 1.6; 95% CI, 1.1–2.3, p = 0.009) than deep white matter hyperintensities (aOR for the highest vs. lowest quartile, 1.3; 95% CI, 0.9–1.9, p = 0.16). No significant association was observed between TMAO and lacunes or cerebral microbleeds. Choline showed trends similar to that of TMAO in the association with cerebral small vessel disease.

Conclusions: In patients with ischemic stroke or transient ischemic attack, TMAO and choline appear to be associated with white matter hyperintensities, but not with lacunes or cerebral microbleeds; TMAO and choline were associated with increased risk of a greater periventricular, rather than deep, white matter hyperintensities burden.

Trimethyllysine, vascular risk factors and outcome in acute ischemic stroke (MARK-STROKE)

Trimethyllysine (TML) is involved in the generation of the pro-atherogenic metabolite trimethylamine-N-oxide (TMAO) by gut microbiota. In clinical studies, elevated TML levels predicted major adverse cardiovascular events (MACE) in patients with acute or stable coronary artery disease (CAD). In contrast to cardiovascular patients, the role of TML in patients with acute cerebral ischemia is unknown. Here, we evaluated circulating TML levels in 374 stroke patients from the prospective biomarkers in stroke (MARK-STROKE) study. Compared with 167 matched healthy controls, acute ischemic stroke patients had lower median TML plasma concentrations, i.e. 0.71 vs. 0.47 µmol/L (p < 0.001) and this difference persisted after adjusting for age and sex. TML plasma concentrations were associated with age, serum creatinine, glucose, cholesterol and lysine. Patients with prevalent arterial hypertension, atrial fibrillation or a history of myocardial infarction had increased TML levels, but this observation was not independent of age, sex and GFR. In 274 patients, follow-up data were available. During a median follow-up of 284 [25th-75th percentile: 198, 431] days, TML was not associated with incident MACE (stroke, myocardial infarction, death). In summary, our data suggests a different role of TML in acute ischemic stroke compared with CAD patients.

Choline Pathway Nutrients and Metabolites and Cognitive Impairment After Acute Ischemic Stroke

BACKGROUND AND PURPOSE

Choline metabolism was suggested to play pathophysiological roles in nervous system and atherosclerosis development. However, little is known about the impacts of choline pathway nutrients and metabolites on poststroke cognitive impairment. We aimed to prospectively investigate the relationships between circulating choline, betaine, and trimethylamine N-oxide with cognitive impairment among acute ischemic stroke patients.

METHODS

We derived data from CATIS (China Antihypertensive Trial in Acute Ischemic Stroke). Plasma choline, betaine, and trimethylamine N-oxide concentrations at baseline were measured in 617 participants. Cognitive impairment was evaluated using the Mini-Mental State Examination and the Montreal Cognitive Assessment. Reclassification and calibration of models with choline-related biomarkers were evaluated.

RESULTS

Plasma choline and betaine were inversely associated with cognitive impairment. Compared with the lowest tertile, adjusted odds ratios of Mini-Mental State Examination-defined cognitive impairment for participants in the highest tertiles of choline and betaine were 0.59 (95% CI, 0.39-0.90) and 0.60 (95% CI, 0.39-0.92), respectively. In addition, both choline and betaine offered incremental predictive ability over the basic model with established risk factors, shown by increase in net reclassification improvement and integrated discrimination improvement. There were similar significant relationships between choline and betaine with cognitive impairment as defined by the Montreal Cognitive Assessment. However, plasma trimethylamine N-oxide was only associated with cognitive impairment evaluated using the Mini-Mental State Examination; the adjusted odds ratio was 1.33 (95% CI, 1.04-1.72) for each 1-SD increment of trimethylamine N-oxide.

CONCLUSIONS

Patients with higher choline and betaine levels had lower risk of cognitive impairment after ischemic stroke, supporting promising prognostic roles of choline pathway nutrients for poststroke cognitive impairment.

Microbiome and ischemic stroke: A systematic review

Background

Ischemic stroke is one of the non-communicable diseases that contribute to the significant number of deaths worldwide. However, the relationship between microbiome and ischemic stroke remained unknown. Hence, the objective of this study was to perform systematic review on the relationship between human microbiome and ischemic stroke.

Methods

A systematic review on ischemic stroke was carried out for all articles obtained from databases until 22^nd October 2020. Main findings were extracted from all the eligible studies.

Results

Eighteen eligible studies were included in the systematic review. These studies suggested that aging, inflammation, and different microbial compositions could contribute to ischemic stroke. Phyla Firmicutes and Bacteroidetes also appeared to manipulate post-stroke outcome. The important role of microbiota-derived short-chain fatty acids and trimethylamine N-oxide in ischemic stroke were also highlighted.

Conclusions

This is the first systematic review that investigates the relationship between microbiome and ischemic stroke. Aging and inflammation contribute to differential microbial compositions and predispose individuals to ischemic stroke.

Using matrix-induced ion suppression combined with LC-MS/MS for quantification of trimethylamine-N-oxide, choline, carnitine and acetylcarnitine in dried blood spot samples

Recently, there has been significant interest in the influences of the human gut microbiota on many diseases, such as cardiovascular disease (CVD) and metabolic disorders. Trimethylamine N-oxide (TMAO) is one of the most frequently discussed gut-derived metabolites. Dried blood spot (DBS) sampling has been regarded as an attractive alternative sampling strategy for clinical studies and offers many advantages. For DBS sample processing, whole-spot analysis could minimize hematocrit-related bias, but it requires blood volume calibration. This study developed a method combining matrix-induced ion suppression (MIIS) with liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) to estimate blood volume and quantify TMAO and its precursors and derivatives, including choline, carnitine and acetylcarnitine, in DBSs. The MIIS method used an ion suppression indicator (ISI) to measure the extent of ion suppression caused by the blood matrix, which was related to the blood volume. The results showed that the volume estimation accuracy of the MIIS method was within 91.7-109.7%. The combined MIIS and LC-MS/MS method for quantifying TMAO, choline, carnitine and acetylcarnitine was validated in terms of linearity, precision and accuracy. The quantification accuracy was within 91.2-113.2% (with LLOQ <119%), and the imprecision was below 8.0% for all analytes. A stability study showed that the analytes in DBSs were stable at all evaluated temperatures for at least 30 days. The validated method was applied to quantify DBS samples (n = 56). Successful application of the new method demonstrated the potential of this method for real-world DBS samples and to facilitate our understanding of the gut microbiota in human health.

NAFLD and increased risk of cardiovascular disease: clinical associations, pathophysiological mechanisms and pharmacological implications

Non-alcoholic fatty liver disease (NAFLD) is a public health problem, affecting up to a third of the world's adult population. Several cohort studies have consistently documented that NAFLD (especially in its more advanced forms) is associated with a higher risk of all-cause mortality and that the leading causes of death among patients with NAFLD are cardiovascular diseases (CVDs), followed by extrahepatic malignancies and liver-related complications. A growing body of evidence also indicates that NAFLD is strongly associated with an increased risk of major CVD events and other cardiac complications (ie, cardiomyopathy, cardiac valvular calcification and cardiac arrhythmias), independently of traditional cardiovascular risk factors. This narrative review provides an overview of the literature on: (1) the evidence for an association between NAFLD and increased risk of cardiovascular, cardiac and arrhythmic complications, (2) the putative pathophysiological mechanisms linking NAFLD to CVD and other cardiac complications and (3) the current pharmacological treatments for NAFLD that might also benefit or adversely affect risk of CVD.

High plasma levels of trimethylamine N-oxide are associated with poor outcome in intracerebral hemorrhage patients

BACKGROUND AND AIMS

As a gut microbiota-dependent metabolite, trimethylamine N-oxide (TMAO) has been implicated in cardiovascular diseases. We aimed to investigate the relationship between the clinical outcomes and plasma TMAO concentrations in patients with acute intracerebral hemorrhage.

METHODS

From January 2019 to October 2019, we prospectively enrolled intracerebral hemorrhage patients diagnosed within 6 h of symptoms onset. Plasma TMAO levels was measured for all patients within 24 h after admission. The primary outcome was functional outcome at 3 months. Patients were dichotomized as good (modified Rankin scale 0-3) and poor (modified Rankin scale 4-6). Secondary outcome included early neurological deterioration (END) and hematoma enlargement (HE).

RESULTS

There were 307 patients (57.7% male) with a mean age of 66.8 years included in the study. The median TMAO levels was 3.2 μmol/L. END, HE, and 3-month poor outcome were detected in 59 (19.2%), 54 (17.6%), and 139 (45.3%) patients, respectively. After adjusting for potential confounders, the odds ratio for the highest quartile of TMAO compared with the lowest quartile was 3.65 (95% confidence interval, 1.43-9.30) for 3-month poor outcome. Furthermore, multiple-adjusted spline regression model showed a linear association between TMAO levels and poor outcome at 3 months (P = 0.013 for linearity). Similar significant findings were observed when functional outcome was analyzed by continuous mRS score. No association was found between TMAO levels and END and HE.

CONCLUSIONS

The present study demonstrated that increased TMAO levels were independently correlated with 3-month function outcome after intracerebral hemorrhage.