Plasma Trimethylamine N-oxide Research Articles

Correlation Between Plasma Trimethylamine N-Oxide and Lipid Levels in Hyperlipidemic Patients

To investigate the correlation between the plasma levels of trimethylamine N-oxide (TMAO) and lipid levels in hyperlipidemic patients. A total of 130 patients who received treatment and underwent coronary angiography at the Heart Center, the First Affiliated Hospital of Xinjiang Medical University between March 2019 and March 2021 were enrolled. Patients' plasma TMAO levels were determined by stable isotope liquid chromatography/mass spectrometry. The correlation between plasma TMAO levels and the levels of lipids, including triglycerides (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C), was analyzed. Patients with hyperlipidemia had higher plasma TMAO levels (μmol/L) than patients without hyperlipidemia did (6.73±5.40 vs. 3.82±2.65), with the difference being statistically significant ( P<0.05). After controlling for the effects of age and body mass index, partial correlation analysis revealed that plasma TMAO levels were positively correlated with plasma TG ( r=0.286, P<0.001) and negatively correlated with HDL-C ( r=-0.366, P<0.001). There is a correlation between plasma TMAO levels and lipid levels in hyperlipidemic patients.

Trimethylamine N-oxide and risk of inflammatory bowel disease: A Mendelian randomization study.

A previous study suggested that inflammatory bowel disease (IBD) patients have low plasma levels of trimethylamine N-oxide (TMAO). In the present study, we examined this hypothesis using Mendelian randomization analysis. We used summary statistics data for single-nucleotide polymorphisms associated with plasma levels of TMAO, and the corresponding data for IBD from a genome-wide association meta-analysis of 59,957 individuals (25,042 diagnosed IBD cases, 34,915 controls). The association between genetically predicted plasma TMAO levels and IBD showed odds ratios (95% confidence interval [CI]) per 1 interquartile range increment (per 2.4 μmol/L) in TMAO levels were 0.91 (0.81-1.01, P = .084) for IBD, 0.88 (0.76-1.02, P = .089) for ulcerative colitis, 0.91 (0.79-1.05, P = .210) for Crohn disease. There was no evidence for pleiotropy based on the Mendelian randomization-Egger regression analyses (P-intercept = 0.669 for IBD). Further investigations would be needed to understand the causal relationship between TMAO and IBD.

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

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

Effect of a 3-month L-carnitine supplementation and resistance training program on circulating markers and bone mineral density in postmenopausal women: a randomized controlled trial

BackgroundHigher circulating levels of trimethylamine N-oxide (TMAO), which is a metabolite that can be produced by the gut microbiota from L-carnitine (LC), have been associated with bone mineral density (BMD). Because LC supplementation can improve bone density and microstructural properties in animal models, this study aimed to examine the effects of 12 weeks of LC supplementation on BMD and selected blood markers involved in bone metabolism of postmenopausal women participating in a resistance training (RT) program.MethodsTwenty-seven postmenopausal women, who had not been treated for osteoporosis, with a total T-score above − 3.0 and no diet differences completed 12 weeks of RT. The participants’ diets were supplemented with either 1 g of LC-L-tartrate and 3 g of leucine per day (LC group) or 4 g of leucine per day as a placebo (PLA group), in a double-blind fashion.ResultsAfter the intervention in the LC group, plasma total carnitine and serum decorin levels were higher than the corresponding preintervention values (p = 0.040 and p = 0.042, respectively). Moreover, plasma TMAO and serum SPARC levels were higher in the LC group than the corresponding postintervention values in the PLA group (p < 0.001 and p = 0.030, respectively). No changes in the BMD were observed after 3 months of the intervention.ConclusionsTwelve weeks of LC supplementation during RT program increased plasma TMAO levels and appeared to affect signaling molecules, as indicated by the increase in the resting SPARC and decorin levels, with no significant modification in the BMD.Trial registrationRetrospectively registered at the ClinicalTrials.gov (NCT05120011).

Utility of Trimethylamine Oxide (TMAO) in Predicting Early Neurological Deterioration after Acute Ischemic Stroke.

To investigate whether plasma trimethylamine N-oxide (TMAO) levels might predict early neurological deterioration (END) in individuals with acute ischemic stroke. Cohort study. Place and Duration of the Study:Jiulongpo District Hospital of Traditional Chinese Medicine, Chongqing City, China, from January 2020 to December 2021. Patients presenting with ischemic stroke were classified into the END group and the non-END group. The National Institutes of Health Stroke Scale (NIHSS) total increasing by 2 points or more within 72 hours of admission was the definition of the END. Plasma TMAO levels were determined by high-performance liquid chromatographic and tandem mass spectrometry. Twenty-six (25%) of the 104 patients, diagnosed with END exhibited higher TMAO levels after admission (median 1.438 vs. 0.449 nmol/mL, p=0.001). Elevated plasma TMAO levels were significant predictors of END in univariate logistic analysis. After controlling for age, gender, and cardiovascular risk factors in the multivariate conditional logistic regression model, the plasma TMAO levels in the END group remained significantly higher than those in the non-END group (OR=6.646, 95% CI 2.434-18.147, p<0.001). In receiver operator characteristic (ROC) analysis, the sensitivity and specificity of TMAO in distinguishing the END group and the non-END group at 0.564 nmol/mL cutoff value were 0.885 and 0.679, respectively. According to this research, the development of END on admission in patients with acute ischemic stroke may be positively correlated with the elevation in plasma TMAO levels. Trimethylamine N-oxide level, Acute ischemic stroke, Early neurological deterioration, NIHSS score.

Plasma Carnitine, Choline, -Butyrobetaine, and Trimethylamine N-oxide, but not Zonulin, are reduced in overweight/obese Patients with Pre/diabetes or Impaired Glycemia

Background and Aims: Zonulin, carnitine, choline, g-butyrobetaine (g-BB), and trimethylamine N-oxide (TMAO) are intricately involved in metabolic anomalies and type 2 diabetes mellitus (T2D). This study aimed to compare and correlate the plasma levels of zonulin, carnitine, choline, g-butyrobetaine, and TMAO, along with the adiposity, atherogenicity, surrogate insulin resistance (sIR), and proinflammatory hematological indices of newly diagnosed drug-naive pre-diabetic and diabetic patients vs. apparently healthy normoglycemic controls.&#x0D; Methods: In a cross-sectional study, 30 normoglycemic subjects (controls) and 16 pre-diabetic (PreDM) and 14 type 2 diabetes (T2D) cases, that were gender and age-matched, were enrolled. Zonulin, carnitine, choline, g-BB, and TMAO plasma levels were appraised using colorimetric assays. A comparison between the study groups was conducted by ANOVA while Spearman rank correlations between the metabolic risk biomarkers and between the risk markers and adiposity, sIR, atherogenicity, and proinflammatory hematological indices were also examined.&#x0D; Results: Significant intergroup discrepancies in plasma carnitine, choline, g-BB, and TMAO (but not zonulin) could be recognized in the cases vs. controls. Fasting blood glucose (FPG), glycated hemoglobin (A1C), triglycerides (TG), body mass index (BMI), lipid accumulation product (LAP), visceral adiposity index (VAI), atherogenic index of plasma (AIP), and all sIR were outstandingly higher in the cases vs. controls. Blood indices lacked a scoring value to discriminate cases from controls. Inadvertently, no relation was found between plasma carnitine, choline, g-BB, TMAO, or zonulin in cases. Among the rest of the markers and sIR indices; The triglyceride-glucose-body mass index (TyG*BMI) related reciprocally to zonulin. Noticeably, among adiposity indices, TyG*BMI, triglyceride glucose-waist circumference (TyG*WC), and metabolic score for insulin resistance (MetS-IR) positively associated with waist circumference (WC), hip circumference (HC), BMI, body adiposity index (BAI), and waist-to-height ratio (WHtR). Exceptionally LAP proportionally correlated with all sIR. TyG*WC and MetS-IR correlated directly with the conicity index (CI). WHR directly associated with triglyceride-glucose (TyG) index and TyG*WC. Remarkably, the TyG index (but not TyG*BMI, TyG*WC, or MetS-IR) positively associated with all atherogenicity indices and RDW (but none of other blood indices). TMAO correlated inversely (P &lt; 0.05) and moderately with choline. Distinctively, carnitine associated negatively with TC (P &lt; 0.05). Both choline and carnitine related similarly and directly with PLR but inversely with lymphocytes (p &lt;0.05). Effectively, gButyrobetaine associated with both WC and the TyG-WC index equally negatively (P &lt; 0.05). Substantially, gButyrobetaine correlated inversely with both atherogenic LDL-C/HDL-C ratio and MPV (P &lt; 0.05). No pronounced relations were detected between the five microbiome signature determinants and glycemic control parameters (FBG and A1C %), sIR (TyG, TyG-BMI or MetS-IR), adiposity (WHR, WHtR, CI, BAI, LAP, or VAI), atherogenicity indices (TC/HDL-C ratio, non‑HDL‑C/HDL-C ratio, or AIP), or blood indices (NLR or MLR).Conclusion: Given the intergroup discrepancies in sIR, plasma zonulin, carnitine, choline, g-BB, and TMAO along with their elective correlations with indices and clinical parameters of metabolic dysregulations, our study cannot rule out any possible molecular crosstalk and interplay of the biomarkers studied with the pathophysiology of prediabetes/diabetes. All in all, plasma zonulin, carnitine, choline, g-BB, and TMAO with sIR can be putative surrogates for molecular cardiometabolic risk biomarkers to use as prognostic/predictive tools for the diagnosis/prevention and potential targets for prediabetes/diabetes management modalities.

Trimethylamine N-Oxide Concentration and Blood Pressure in Young Healthy Men and Women: A Replicated Crossover Study.

Trimethylamine N-oxide (TMAO), a gut-derived metabolite and marker of gut dysbiosis, has been linked to hypertension. Blood pressure is proposed to be elevated in hormonal contraceptive users and males compared to age-matched eumenorrheic females, but the extent to which TMAO differs between these populations has yet to be investigated. Peripheral and central blood pressure were measured, with the latter determined via applanation tonometry, and plasma TMAO concentration was assessed using liquid chromatography-tandem mass spectrometry. The following variables were assessed on two occasions in each of the following conditions: the early follicular phase (EFP) and mid-luteal phase (MLP) in eumenorrheic women (n = 13), and the pill-free interval (INACTIVE) and pill consumption days (ACTIVE) in women using oral contraceptive pills (n = 12), and in men (n = 22). Briefly, 17-β-estradiol and progesterone concentrations were quantified via ELISA in all females. There were no differences in TMAO concentration between EFP (2.9 ± 1.7 μmol/L) and MLP (3.2 ± 1.1 μmol/L), between INACTIVE (3.3 ± 2.9 μmol/L) and ACTIVE (2.3 ± 1.1 μmol/L) days, or between men (3.0 ± 1.8 μmol/L), eumenorrheic women (3.0 ± 1.3 μmol/L) and contraceptive users (2.8 ± 1.4 μmol/L). Blood pressure was consistent across the menstrual cycle and pill days, but brachial systolic blood pressure was higher in males than females. There were no differences in brachial diastolic blood pressure or central blood pressure between the sexes. Repeated measures of TMAO, blood pressure, 17-β-estradiol and progesterone were consistent in all populations. These findings suggest that the link between TMAO and blood pressure is limited in healthy young adults.

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.

The roles of trimethylamine-N-oxide in atherosclerosis and its potential therapeutic aspect: A literature review.

Current research supports the evidence that the gut microbiome (GM), which consist of gut microbiota and their biologically active metabolites, is associated with atherosclerosis development. Trimethylamine-N-oxide (TMAO), a metabolite produced by the GM through trimethylamine (TMA) oxidation, significantly enhances the formation and vulnerability of atherosclerotic plaques. TMAO promotes inflammation and oxidative stress in endothelial cells, leading to vascular dysfunction and plaque formation. Dimethyl-1-butanol (DMB), iodomethylcholine (IMC) and fluoromethylcholine (FMC) have been recognized for their ability to reduce plasma TMAO by inhibiting trimethylamine lyase, a bacterial enzyme involved in the choline cleavage anaerobic process, thus reducing TMA formation. Conversely, indole-3-carbinol (I3C) and trigonelline inhibit TMA oxidation by inhibiting flavin-containing monooxygenase-3 (FMO3), resulting in reduced plasma TMAO. The combined use of inhibitors of choline trimethylamine lyase and flavin-containing monooxygenase-3 could provide novel therapeutic strategies for cardiovascular disease prevention by stabilizing existing atherosclerotic plaques. This review aims to present the current evidence of the roles of TMA/TMAO in atherosclerosis as well as its potential therapeutic prevention aspects.

Association of urine and plasma ADMA with atherosclerotic risk in DKD cardiovascular disease risk in diabetic kidney disease: findings from the Chronic Renal Insufficiency Cohort (CRIC) study.

Chronic kidney disease (CKD) is associated with atherosclerotic cardiovascular disease (ASCVD) risk, especially among those with diabetes. Altered metabolism of solutes that accumulate in CKD [asymmetric dimethylarginine (ADMA), symmetric dimethylarginine (SDMA) and trimethylamine N-oxide (TMAO)] may reflect pathways linking CKD with ASCVD. This case-cohort study included Chronic Renal Insufficiency Cohort participants with baseline diabetes, estimated glomerular filtration rate <60mL/min/1.73 m2, and without prior history for each outcome. The primary outcome was incident ASCVD (time to first myocardial infarction, stroke or peripheral artery disease event) and secondary outcome was incident heart failure. The subcohort comprised randomly selected participants meeting entry criteria. Plasma and urine ADMA, SDMA and TMAO concentrations were determined by liquid chromatography-tandem mass spectrometry. Associations of uremic solute plasma concentrations and urinary fractional excretions with outcomes were evaluated by weighted multivariable Cox regression models, adjusted for confounding covariables. Higher plasma ADMA concentrations (per standard deviation) were associated with ASCVD risk [hazard ratio (HR) 1.30, 95% confidence interval (CI) 1.01-1.68]. Lower fractional excretion of ADMA (per standard deviation) was associated with ASCVD risk (HR 1.42, 95% CI 1.07-1.89). The lowest quartile of ADMA fractional excretion was associated with greater ASCVD risk (HR 2.25, 95% CI 1.08-4.69) compared with the highest quartile. Plasma SDMA and TMAO concentration and fractional excretion were not associated with ASCVD. Neither plasma nor fractional excretion of ADMA, SDMA and TMAO were associated with incident heart failure. These data suggest that decreased kidney excretion of ADMA leads to increased plasma concentrations and ASCVD risk.

Ginger essential oil and citral ameliorates atherosclerosis in ApoE−/− mice by modulating trimethylamine-N-oxide and gut microbiota

Recently, the role of the gut microbiota in diseases, including cardiovascular disease (CVD), has gained considerable research attention. Trimethylamine-N-oxide (TMAO), which is formed during ʟ-carnitine metabolism, promotes the formation of atherosclerotic plaques, causing thrombosis. Here, we elucidated the anti-atherosclerotic effect and mechanism of ginger (Zingiber officinale Roscoe) essential oil (GEO) and its bioactive compound citral in Gubra Amylin NASH (GAN) diet with ʟ-carnitine-induced atherosclerosis female ApoE−/− mice. Treatment with GEO at both low and high doses and citral inhibited the formation of aortic atherosclerotic lesions, improved plasma lipid profile, reduced blood sugar, improved insulin resistance, decreased plasma TMAO levels, and inhibited plasma inflammatory cytokines, especially interleukin-1β. Additionally, GEO and citral treatment modulated gut microbiota diversity and composition by increasing the abundance of beneficial microbes and decreasing the abundance of CVD-related microbes. Overall, these results showed that GEO and citral may serve as potential dietary supplements for CVD prevention by improving gut microbiota dysbiosis.

C86 ASSOCIATION OF PLASMA TMAO VALUES WITH ANOTHER ISCHEMIC EVENT DURING LONG–TERM FOLLOW–UP IN PATIENTS WITH MYOCARDIAL INFARCTION

Abstract Background Elevated plasma trimethylamine N–oxide (TMAO) levels, a metabolite derived from the intestinal microbiota, are closely related to atherosclerosis due to its involvement in increased inflammation, oxidative stress and cholesterol reverse transport. Objectives Blood samples were collected at admission from 81 patients who survived acute myocardial infarction (AMI) and from 10 healthy individuals. TMAO concentrations were measured by means of liquid chromatography–tandem mass spectrometry with an aim to evaluate the predictive value of this biomarker in terms of another major event during long–term follow–up. Results Patients with AMI have significantly higher median plasma TMAO concentration compared to healthy individuals (respectively, 1.62 (1.37 – 2.25) µM vs 0.55 (0.35 – 0.74) µM, p &amp;lt; 0.0001). Considering only patients with AMI, TMAO values positively correlated with pro–inflammatory markers CRP and TNF–α. In addition, TMAO positively correlated with creatinine and negatively correlated with GFR. Moreover, we noted the trend of higher TMAO values among patients with diabetes mellitus compared to patients without (1.68 (1.44 – 5.43) µM vs 1.59 (1.33 – 2.099) µM, p=0.065). During a median follow–up of 61.74 (59.34 – 64.24) months, 10 patients suffered another infarction. Those individuals had significantly higher TMAO values compared to subjects without another ischemic event (respectively, 2.29 (1.60 – 6.49) µM vs 1.60 (1.34 – 2.09) µM, p = 0.026). Kaplan–Meier analysis confirmed that elevated values of TMAO were associated with the risk of another infarction (p=0.029), whereas multivariate Cox regression analysis did not demonstrate the prognostic value of TMAO towards re–infarction probably due to the small cohort. Conclusions Higher plasma TMAO values at admission in patients with AMI are associated with re–infarction at long–term follow–up.

The Gut Microbial Metabolite Trimethylamine N-Oxide is Linked to Specific Complications of Systemic Sclerosis.

Systemic sclerosis (SSc) is a rare immune-mediated connective tissue disease characterized by fibrosis of the skin and internal organs, whose pathogenesis is not fully understood. Recent studies have revealed dysbiosis in patients with systemic sclerosis and have indicated the possible role of the microbiota and its metabolites in the pathogenesis of the disease. Trimethylamine N-oxide (TMAO) is a compound produced by dysbiotic microbiota observed at higher concentrations in several autoimmune diseases. To determine concentrations of the bacteria-derived metabolite TMAO in patients with systemic sclerosis and to assess possible correlation between TMAO and a specific manifestation of the disease. The study included 63 patients with SSc and 47 matched control subjects. The concentration of TMAO was measured with high-performance liquid chromatography. Plasma TMAO level was significantly increased in patients with SSc (283.0 [188.5-367.5] ng/mL versus 205.5 [101.0-318.0] ng/mL; p < 0.01). An increased concentration of TMAO was observed in patients with concomitant interstitial lung disease (ILD) (302.0 ng/mL [212.0-385.5] ng/mL versus 204.0 [135.5-292.0] ng/mL; p < 0.01) and esophageal dysmotility (289.75 [213.75-387.5] ng/mL versus 209.5 ng/mL [141.5-315.0] ng/mL; p < 0.05) compared to patients without these complications. Furthermore, TMAO concentration exhibited significant correlation with markers of heart involvement (left ventricle ejection fraction, NT-proBNP), marker of ILD severity and Scleroderma Clinical Trials Consortium Damage Index. The concentration of TMAO, gut microbiota-associated metabolite, is increased in systemic sclerosis, particularly in patients with advanced organ involvement. This is the first study evaluating plasma TMAO in systemic sclerosis. Bacterial metabolites may be a link between dysbiosis and organ involvement in the course of the disease. Modulation of gut bacterial-derived metabolites may represent a new therapeutic approach in the management of systemic sclerosis.

Exploratory Transcriptomic Profiling Reveals the Role of Gut Microbiota in Vascular Dementia.

Stroke is the second most common cause of cognitive impairment and dementia. Vascular dementia (VaD), a cognitive impairment following a stroke, is common and significantly impacts the quality of life. We recently demonstrated via gut microbe transplant studies that the gut microbe-dependent trimethylamine-N-oxide (TMAO) pathway impacts stroke severity, both infarct size and long-term cognitive outcomes. However, the molecular mechanisms that underly the role of the microbiome in VaD have not been explored in depth. To address this issue, we performed a comprehensive RNA-sequencing analysis to identify differentially expressed (DE) genes in the ischemic cerebral cortex of mouse brains at pre-stroke and post-stroke day 1 and day 3. A total of 4016, 3752 and 7861 DE genes were identified at pre-stroke and post-stroke day 1 and day 3, respectively. The Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis indicated pathways of neurodegeneration in multiple diseases, chemokine signaling, calcium signaling, and IL-17 signaling as the key enriched pathways. Inflammatory response genes interleukin-1 beta (Il-1β), chemokines (C-X-C motif chemokine ligand 10 (Cxcl10), chemokine ligand 2 (Ccl2)), and immune system genes (S100 calcium binding protein 8 (S100a8), lipocalin-2 (Lcn2)) were among the most significantly upregulated genes. Hypocretin neuropeptide precursor (Hcrt), a neuropeptide, and transcription factors such as neuronal PAS domain protein 4 (Npas4), GATA binding protein 3 (Gata3), and paired box 7 (Pax7) were among the most significantly downregulated genes. In conclusion, our results indicate that higher plasma TMAO levels induce differential mRNA expression profiles in the ischemic brain tissue in our pre-clinical stroke model, and the predicted pathways provide the molecular basis for regulating the TMAO-enhanced neuroinflammatory response in the brain.

Trimethylamine N-Oxide (TMAO) Inducing Endothelial Injury: UPLC-MS/MS-Based Quantification and the Activation of Cathepsin B-Mediated NLRP3 Inflammasome.

TMAO is a new risk biomarker for cardiovascular disease. With trimethylammonium as its main chemical skeleton, TMAO is structurally similar to many endogenous metabolites, such as acetylcholine, carnitine, phosphorylcholine, etc. The mechanism of TMAO on the pathological process of CVD is still unclear. In this study, the quantitative analysis of plasma TMAO is conducted, and the contribution of Cathepsin B and NLRP3 inflammasome during the process of TMAO-induced endothelial injury was proposed and investigated at animal and cellular levels. Immunofluorescence assay was applied to represent the protein expression of Cathepsin B and NLRP3 inflammasome located at endothelial cells. The results showed that TMAO could disrupt endothelial cells permeability to induce endothelial injury, meanwhile, TMAO could increase NLRP3 inflammasome activation and promote the activity and expression of Cathepsin B in vitro and in vivo, whereas inhibition of NLRP3 inflammasome activation by MCC950 could protect the endothelial cells from TMAO associated endothelial injury via Cathepsin B. The study reveals that TMAO can cause endothelial injury via Cathepsin B-dependent NLRP3 inflammasome, and inhibition of Cathepsin B and NLRP3 inflammasome can reduce the TMAO-induced damage. The results provide new insight into the role of TMAO in CVD, which can be a potential therapeutic target for disease treatment and drug design.

Gut Microbiota-Derived Trimethylamine N-Oxide Contributes to Abdominal Aortic Aneurysm Through Inflammatory and Apoptotic Mechanisms.

Large-scale human and mechanistic mouse studies indicate a strong relationship between the microbiome-dependent metabolite trimethylamine N-oxide (TMAO) and several cardiometabolic diseases. This study aims to investigate the role of TMAO in the pathogenesis of abdominal aortic aneurysm (AAA) and target its parent microbes as a potential pharmacological intervention. TMAO and choline metabolites were examined in plasma samples, with associated clinical data, from 2 independent patient cohorts (N=2129 total). Mice were fed a high-choline diet and underwent 2 murine AAA models, angiotensin II infusion in low-density lipoprotein receptor-deficient (Ldlr-/-) mice or topical porcine pancreatic elastase in C57BL/6J mice. Gut microbial production of TMAO was inhibited through broad-spectrum antibiotics, targeted inhibition of the gut microbial choline TMA lyase (CutC/D) with fluoromethylcholine, or the use of mice genetically deficient in flavin monooxygenase 3 (Fmo3-/-). Finally, RNA sequencing of in vitro human vascular smooth muscle cells and in vivo mouse aortas was used to investigate how TMAO affects AAA. Elevated TMAO was associated with increased AAA incidence and growth in both patient cohorts studied. Dietary choline supplementation augmented plasma TMAO and aortic diameter in both mouse models of AAA, which was suppressed with poorly absorbed oral broad-spectrum antibiotics. Treatment with fluoromethylcholine ablated TMAO production, attenuated choline-augmented aneurysm initiation, and halted progression of an established aneurysm model. In addition, Fmo3-/- mice had reduced plasma TMAO and aortic diameters and were protected from AAA rupture compared with wild-type mice. RNA sequencing and functional analyses revealed choline supplementation in mice or TMAO treatment of human vascular smooth muscle cells-augmented gene pathways associated with the endoplasmic reticulum stress response, specifically the endoplasmic reticulum stress kinase PERK. These results define a role for gut microbiota-generated TMAO in AAA formation through upregulation of endoplasmic reticulum stress-related pathways in the aortic wall. In addition, inhibition of microbiome-derived TMAO may serve as a novel therapeutic approach for AAA treatment where none currently exist.

Gut-Derived Metabolite, Trimethylamine-N-oxide (TMAO) in Cardio-Metabolic Diseases: Detection, Mechanism, and Potential Therapeutics.

Trimethylamine N-oxide (TMAO) is a biologically active gut microbiome-derived dietary metabolite. Recent studies have shown that high circulating plasma TMAO levels are closely associated with diseases such as atherosclerosis and hypertension, and metabolic disorders such as diabetes and hyperlipidemia, contributing to endothelial dysfunction. There is a growing interest to understand the mechanisms underlying TMAO-induced endothelial dysfunction in cardio-metabolic diseases. Endothelial dysfunction mediated by TMAO is mainly driven by inflammation and oxidative stress, which includes: (1) activation of foam cells; (2) upregulation of cytokines and adhesion molecules; (3) increased production of reactive oxygen species (ROS); (4) platelet hyperreactivity; and (5) reduced vascular tone. In this review, we summarize the potential roles of TMAO in inducing endothelial dysfunction and the mechanisms leading to the pathogenesis and progression of associated disease conditions. We also discuss the potential therapeutic strategies for the treatment of TMAO-induced endothelial dysfunction in cardio-metabolic diseases.

Consumption of Fish in Chronic Kidney Disease - A Matter of Depth.

Fish is an excellent source of ω-3 polyunsaturated fatty acids (PUFAs), amino acids, collagen, vitamins, and iodine and its intake is associated with health benefits, mainly reduces risk of cardiovascular mortality. However, recent studies have shown that fish is also an important source of trimethylamine N-oxide (TMAO), a uremic toxin produced by the gut microbiota that promotes an increased risk of cardiovascular diseases. In patients with chronic kidney disease (CKD), TMAO levels are markedly increased due to gut dysbiosis and reduced kidney function. No study has yet evaluated the effects of a fish-rich diet on TMAO plasma levels and cardiovascular outcomes. This review discusses the pros and cons of a fish-rich diet in patients with CKD - a matter of depth.

Trimethylamine N-oxide is associated with long-term mortality risk: the multi-ethnic study of atherosclerosis.

Little is known about associations of trimethylamine N-oxide (TMAO), a novel gut microbiota-generated metabolite of dietary phosphatidylcholine and carnitine, and its changes over time with all-cause and cause-specific mortality in the general population or in different race/ethnicity groups. The study aimed to investigate associations of serially measured plasma TMAO levels and changes in TMAO over time with all-cause and cause-specific mortality in a multi-ethnic community-based cohort. The study included 6,785 adults from the Multi-Ethnic Study of Atherosclerosis. TMAO was measured at baseline and year 5 using mass spectrometry. Primary outcomes were adjudicated all-cause mortality and cardiovascular disease (CVD) mortality. Secondary outcomes were deaths due to kidney failure, cancer, or dementia obtained from death certificates. Cox proportional hazards models with time-varying TMAO and covariates assessed the associations with adjustment for sociodemographics, lifestyles, diet, metabolic factors, and comorbidities. During a median follow-up of 16.9 years, 1704 participants died and 411 from CVD. Higher TMAO levels associated with higher risk of all-cause mortality [hazard ratio (HR): 1.12, 95% confidence interval (CI): 1.08-1.17], CVD mortality (HR: 1.09, 95% CI: 1.00-1.09), and death due to kidney failure (HR: 1.44, 95% CI: 1.25-1.66) per inter-quintile range, but not deaths due to cancer or dementia. Annualized changes in TMAO levels associated with higher risk of all-cause mortality (HR: 1.10, 95% CI: 1.05-1.14) and death due to kidney failure (HR: 1.54, 95% CI: 1.26-1.89) but not other deaths. Plasma TMAO levels were positively associated with mortality, especially deaths due to cardiovascular and renal disease, in a multi-ethnic US cohort.

The role of gut-dependent molecule trimethylamine N-oxide as a novel target for the treatment of chronic kidney disease.

Trimethylamine N-oxide (TMAO) is an intestinal uremic toxin molecule mainly excreted by the kidney. Therefore, the plasma TMAO concentration is significantly increased in chronic kidney disease (CKD) patients, and plasma TMAO can be cleared by dialysis. Furthermore, TMAO damage the kidney mainly through three mechanisms: oxidative stress, inflammation and endoplasmic reticulum stress. Clinical experiments have indicated that higher TMAO levels are strongly related to the elevated incidence and mortality of cardiovascular (CV) events in CKD patients. Moreover, experimental data have shown that high levels of TMAO directly aggravate atherosclerosis, thrombosis and enhance myocardial contractility, resulting in myocardial ischemia and stroke. Specially, there are currently four potential ways to reduce blood TMAO concentration or block the effect of TMAO, including reducing the intake of trimethylamine (TMA) precursors in the diet, regulating the intestinal flora to reduce TMA production, interrupting the role of flavin-dependent monooxygenase isoforms (FMOs) to reduce the generation of TMAO, and blocking the TMAO receptor protein kinase R-like endoplasmic reticulum kinase (PERK). We hope that more clinical studies and clinicians will focus on clinical treatment to reduce the concentration of TMAO and alleviate renal damage.