Plasma Trimethylamine N-oxide Levels Research Articles

Abstract 10334: The Association of Trimethylamine N-oxide (TMAO) with Findings of Vascular Brain Injury on Magnetic Resonance Imaging in the Cardiovascular Health Study (CHS)

Introduction: Findings on MRI of vascular brain injury, such as brain infarcts and white matter hyperintensities, are chronic manifestation of atherosclerosis. A gut-microbiome-generated metabolite, trimethylamine N-oxide (TMAO), is an independent predictor of clinical cardiovascular events. However, no study has examined associations between TMAO and subclinical vascular brain injury in the general population. Hypothesis: TMAO levels are positively associated with evidence of progressive subclinical vascular brain injury on serial MRI scans with incident brain infarcts and white matter worsening. Methods: The Cardiovascular Health Study (CHS) is a community-based prospective cohort study in adults aged >65 years. Plasma TMAO was measured using mass spectrometry from samples collected in 1992-1993 and 1996-1997. Brain MRI was performed at 1991-1994 and again at 1997-1999. White matter was graded on a 10-point scale, higher being worse, and white matter worsening (WMW) was defined by an increase of least one point comparing initial and follow up scans. In these analyses, participants with prior TIA or stroke were excluded. Those with serum TMAO and both MRI scans were included: n=1196 for incident brain infarct and n=1553 for white matter worsening. Logistic regression was used for the association of baseline TMAO levels and incident brain infarcts, and Poisson regression, for the change in TMAO levels and WMW. Models were adjusted for age, sex, race, alcohol use, intake of meat and vegetable, and vascular risk factors. Results: Between the two MRI scans, 191(15.9%) participants had subclinical incident brain infarcts, and 423 (27.2%) participants had WMW. Comparing the highest vs. lowest quartile, the first TMAO were not significantly associated with incident brain infarcts: odds ratio 0.78 (95% CI: 0.49 to 1.25). Again comparing the highest vs. lowest quartile, changes in TMAO were not associated with WMW: 1.08 (0.77 to 1.51). Conclusions: Baseline and changes in plasma TMAO levels were not associated with findings of subclinical vascular brain injury on MRI in older US adults. The associations of TMAO with the adverse clinical events seen in prior clinical samples of patients were not seen at the subclinical level in our population-based study.

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

Abstract Introduction Trimethylamine-N-oxide (TMAO) is a well characterized pro-atherogenic metabolite derived from the microbial processing of phosphatidylcholine and carnitine (usually present in red meat) and subsequent hepatic oxydation, which promotes endothelial dysfunction, platelet activation and thrombosis initiation. Its role concerning cerebral and cardiovascular adverse events has been assessed in various patient subpopulations but not for long term in patients with atrial fibrillation. Methods Baseline TMAO plasma levels were measured by high-performance liquid chromatography/mass spectrometry in plasmas of 2,379 subjects from our multicentric study. Among them, 1,722 participants at time of recruitment underwent brain MRI. Participants were stratified into TMAO tertiles and Cox PH models, linear mixed effect models or logistic mixed effect models were employed adjusting for several risk factors (age, sex, BMI, active and past smoke habit, cystatin c levels, heart failure, diabetes mellitus, hypertension, coronary artery disease and history of TIA/stroke). Subjects were prospectively followed with a median observation time of 4 years. Results Subjects in the highest tertile of TMAO were older (75.4 vs. 70.6 years in low tertile p<0.001) and had significantly more often comorbidities, (26.9% of subjects were diabetic vs. 9.1% in low tertile p<0.001), with higher BMI (28.1 vs 27.0, p<0.001) and worse renal function as assessed by serum cystatin C (1.46 vs 1.07, mg/dl; p<0.001). Heart failure was present in 37.9% participants in the upper compared to 15.8% in the lower tertile. (p<0.001). As shown in Figure 1, Kaplan Meier estimates showed increased cardiovascular mortality with increasing TMAO tertiles (p<0.0001). After adjustment for the abovementioned factors the upper tertile (T3) had an increased hazard ratio (HR) compared to the lowest one (HR 2.36 95% CI 1.56–3.58 p<0.01). Similar trends for global and ischemic stroke occurrences were not found although TMAO levels positively weakly correlated with NIHSS severity (Spearman's coefficient 0.31 p=0.02). Concerning brain MRI findings, TMAO tertiles identified individuals with different prevalence of small non-cortical infarcts (30.5%, 18.1% and 17.4% in high, middle and low tertiles respectively; p<0.001) and when present, larger white matter lesions volumes (5061 mm3, 4158 mm3 and 2970 mm3; p<0.001). After adjustment, the association with small non-cortical infarcts with TMAO levels remained significant in the highest tertile (T3) (OR 1.48 95% CI 1.07–2.05; p=0.02) and a trend towards larger white matter lesions volumes was observed (estimate 1307 95% CI −90–2705; p=0.07). Conclusions TMAO represents a robust prognostic independent biomarker identifying multimorbid, high risk patients for cardiovascular mortality and brain damage. Funding Acknowledgement Type of funding sources: Public Institution(s). Main funding source(s): Swiss National Science Foundation (SNSF) and Theodor und Ida Herzog-Egli Foundation Figure 1. CV mortality according to TMAOFigure 2. Brain lesions assessment

HIGHER CIRCULATING GUT MICROBIOTA-DEPENDENT METABOLITE TRIMETHYLAMINE N-OXIDE PLAYS AN ADVERSE EFFECT ON PULMONARY HYPERTENSION

TOPIC: Pulmonary Vascular Disease TYPE: Original Investigations PURPOSE: The potential role of the gut microbiota-dependent metabolite trimethylamine N-oxide (TMAO) in pulmonary hypertension (PH) has never been elucidated. We aim to explore the association between TMAO and PH. METHODS: PH patients at Fuwai Hospital between October 2018 and February 2020 were enrolled. Patients received follow-up every three to six months through clinic visits. Plasma levels of TMAO were measured and associations with clinical markers including WHO-FC, NT-proBNP, hemodynamic parameters, and exercise capacity were explored. In monocrotaline (MCT)-induced PAH rat models, a normal diet and water supplemented with or without 1% 3,3-dimethyl-1-butanol (DMB), a kind of inhibitor of TMAO, were fed with for 4 weeks. Finally, rats received hemodynamic examinations, and after that blood serum as well as heart and lung tissues were collected. The ratio of right ventricle (RV) over left ventricle (LV) plus the septum was used as an index of RV hypertrophy (RVH). Elastic Van Gieson (EVG) stain was used to explore the changes of pulmonary vascular remodeling. RESULTS: One hundred and three consecutive PH patients were enrolled including patients with idiopathic/heritable pulmonary arterial hypertension (IPAH/HPAH, n=30), chronic thromboembolic PH (CTEPH, n=34), and congenital heart disease-associated PAH (CHD-PAH, n=39). After adjusting for confunders, TMAO levels were positively correlated with clinical disease severity assessed by WHO-FC, and also with NT-proBNP, hemodynamic parameters, and exercise capacity. TMAO responded to guideline-recommended treatment in patients with PH. It was noted that TMAO decreased significantly after treatment in patients with IPAH/HPAH. In linear correlation analysis, change in TMAO was positively associated with change in NT-proBNP (P=0.04) in IPAH/HPAH patients. Animal study showed that the level of TMAO in MCT-induced PH rats (22.2±8.7ng/mL) was higher than the MCT+DMB group (6.6±1.1ng/mL) and the control group (4.3±0.2ng/mL). Compared with MCT group, MCT+DMB group obtained a decreased RVH (30% vs 60%, p<0.001), right arterial pressure (4.4mmHg vs 6.2 mmHg, P=0.035), right ventricular systolic pressure (35.3mmHg vs 63.3mmHg, p<0.001), and mean pulmonary arterial pressure (22.5mmHg vs 39.5mmHg, p<0.001) as well as reduced vascular remodeling of lungs under pathological findings. CONCLUSIONS: TMAO was elevated in accordance with WHO-FC and decreased after guideline-recommended treatment in PH patients indicating higher TMAO might play an adverse effect on PH. The animal findings demonstrated that lower TMAO played a protective effect in MCT-induced PAH, which supported the clinical results. CLINICAL IMPLICATIONS: ①Demonstrated elevated TMAO was a risk factor for PH patients;②TMAO might be regarded as a novel indicator of PH patients. DISCLOSURES: No relevant relationships by Jianing Gao, source=Web Response no disclosure on file for Matthew C Konerman; no disclosure on file for Changming Xiong; No relevant relationships by Yicheng Yang, source=Web Response no disclosure on file for Qixian Zeng; no disclosure on file for Lemin Zheng

Addition of Plasma Myeloperoxidase and Trimethylamine N-Oxide to the GRACE Score Improves Prediction of Near-Term Major Adverse Cardiovascular Events in Patients With ST-Segment Elevation Myocardial Infarction.

Background: The Global Registry of Acute Coronary Events (GRACE) risk score (GRS) is an established powerful model in predicting prognosis of patients with acute coronary syndrome. However, it does not contain pathophysiological biomarkers. Myeloperoxidase (MPO) and trimethylamine N-oxide (TMAO) are novel biomarkers of different pathophysiological processes of acute myocardial infarction, and each of them predicts risk of adverse clinical outcomes. We aimed to investigate whether the addition of MPO and TMAO could improve a GRS-based prediction model in patients with ST-segment elevation myocardial infarction (STEMI). Methods: A prospective cohort of 444 consecutive patients with STEMI who underwent primary percutaneous coronary intervention were enrolled in this study. Plasma levels of MPO and TMAO were measured using samples collected before the interventional procedure. GRS at admission was calculated. Death and nonfatal myocardial infarction were recorded as major adverse cardiac events (MACEs). Kaplan–Meier survival analysis with Cox proportional-hazards regression was used to identify predictive values of MPO and TMAO. Area under the receiver-operator characteristic curve (AUC) and net reclassification improvement (NRI) were calculated to evaluate the increment of predictive value for the combination of MPO and TMAO with GRS in predicting adverse clinical outcomes. Results: During 6 months follow-up, 27 patients suffered MACEs. Both MPO (hazard ratio [HR]: 2.55, 95% confidence interval [CI]: 1.11–5.87; p < 0.05) and TMAO (HR: 4.50, 95% CI: 1.78–11.40, p < 0.01) predicted MACEs at 6 months. The AUC for MPO, TMAO, GRS, and their combination in predicting risk of MACEs at 6 months is 0.642, 0.692, 0.736, and 0.760, respectively. The addition of MPO and TMAO significantly improved the net reclassification of GRS for predicting MACEs at 6 months (NRI: 0.42, p = 0.032). Conclusion: Plasma MPO and TMAO each predict near-term risk of adverse outcomes in patients with STEMI. Furthermore, the combination of MPO and TMAO with GRS enables more accurate prediction of cardiovascular events compared with GRS alone.

Association of plasma trimethylamine N-oxide levels with atherosclerotic cardiovascular disease and factors of the metabolic syndrome

Background and aimsThe association of plasma trimethylamine N-oxide (TMAO) with atherosclerotic cardiovascular disease (ASCVD), diabetes mellitus (DM) and its determinants, as well as the role of TMAO as a predictor for short and long-term mortality, is still under discussion. We investigated associations between four plasma metabolites of the TMAO pathway and different clinical manifestations of atherosclerosis, diabetes determinants, and risk of short and long-term mortality in patients with stable ASCVD, acute myocardial infarction (AMI), cardiogenic shock (CS), and DM in three independent cohorts. MethodsTMAO and its dietary precursors were simultaneously quantified by liquid chromatography-tandem mass spectrometry in a total of 2655 participants of the German Leipzig Research Center for Civilization Diseases (LIFE)-Heart study, LIFE-Adult study, and the European Culprit Lesion Only PCI versus Multivessel PCI in Cardiogenic Shock (CULPRIT-SHOCK) multicenter trial. Associations with ASCVD manifestations, metabolic syndrome, 30-day mortality of patients with AMI and CS, and long-term mortality of subjects with suspected coronary artery disease (CAD) were analyzed. ResultsTMAO plasma levels were not independently associated with stable ASCVD. Elevated TMAO plasma concentrations were independently associated with obesity (odds ratio, 1.23; p < 0.01) and DM (odds ratio, 1.37; p < 0.001) in LIFE-Heart. The latter association was confirmed in LIFE-Adult. We found no association of TMAO plasma levels with short-term mortality in patients with AMI and CS. However, TMAO plasma levels were independent predictors of long-term mortality in patients with suspected CAD (hazard ratio, 1.24; p < 0.05). ConclusionsPotential proatherogenic mechanisms of TMAO seem to have no short-term effect in AMI. Presented associations with diabetes mellitus and obesity suggest that TMAO might have a functional role in metabolic syndrome.

Higher Trimethylamine-N-Oxide Plasma Levels with Increasing Age Are Mediated by Diet and Trimethylamine-Forming Bacteria.

ABSTRACTThe gut microbiota-dependent metabolite trimethylamine-N-oxide (TMAO) is linked to an increased risk for cardiovascular diseases. Trimethylamine (TMA), which is subsequently oxidized to TMAO in the liver, is formed by intestinal bacteria via distinct biochemical routes from dietary precursors that are enriched in animal product-based foods. To get a full picture of the entire process of the diet > gut microbiota > TMAO axis, we quantified potential TMA-forming gut bacteria and plasma metabolites using gene-targeted assays and targeted metabolomics on a subsample (n = 425) of a German population-based cohort study. We specifically compared persons reporting daily meat intake with those that rarely or never consume meat. While meat intake did not predict TMAO plasma levels in our study, two major bacterial TMA-forming pathways were linked to the metabolite’s concentration. Furthermore, advancing age was strongly associated with TMAO. Construction of a structural equation model allowed us to disentangle the different routes that promote higher TMAO levels with increasing age, demonstrating, for the first time, a functional role of gut microbiota in the process, where specific food items augmented abundances of TMA-forming bacteria that were associated with higher TMAO plasma concentrations. Analyses stratified by age showed an association between carotid intima-media thickness and TMAO only in individuals >65 of age, indicating that this group is particularly affected by the metabolite.IMPORTANCE Many cohort studies have investigated the link between diet and plasma TMAO levels, reporting incongruent results, while gut microbiota were only recently included into analyses. In these studies, taxonomic data were recorded that are not a good proxy for TMA formation, as specific members of various taxa exhibit genes catalyzing this reaction, demanding function-based technologies for accurate quantification of TMA-synthesizing bacteria. Using this approach, we demonstrated that abundances of the main components leading to TMAO formation, i.e., TMA precursors and TMA-forming bacteria, are uncoupled and not governed by the same (dietary) factors. Results emphasize that all levels leading to TMA(O) formation should be considered for accurate risk assessment, rejecting the simple view that diets rich in TMA precursors directly lead to increased plasma levels of this hazardous compound. The results can assist in developing strategies to reduce TMAO levels, specifically in the elderly, who are prone to TMAO-associated diseases.

Unraveling the metabolic pathway of choline-TMA-TMAO: Effects of gypenosides and implications for the therapy of TMAO related diseases

Trimethylamine-N-oxide (TMAO) has emerged as a promising new therapeutic target for the treatment of central nervous system diseases, atherosclerosis and other diseases. However, its origin in the brain is unclear. Gynostemma pentaphyllum (Thunb.) Makino can reduce the increase of TMAO level caused by a high fat diet. But its effective chemical composition and specific mechanism have not been reported. The study confirmed that TMA was more easily to penetrate blood brain barrier than TMAO, the MAO enzyme was partly involved in the transformation of the TMA in brain, which further supplemented the choline-TMA-TMAO pathway. Based on the above metabolic pathway, using multi-omics approaches, such as microbiodiversity, metagenomics and lipidomics, it was demonstrated that the reduction of plasma TMAO levels by gypenosides did not act on FMO3 and MAO in the pathway, but remodeled the microbiota and affected the trimethylamine lyase needed in the conversion of choline to TMA in intestinal flora. At the same time, gypenosides interfered with enzymes associated with TCA and lipid metabolism, thus affecting TMAO and lipid metabolism. Considering the bidirectional transformation of phosphatidycholine and choline, lipid metabolism and TMAO metabolism could affected each other to some extent. In conclusion, our study revealed the intrinsic correlation between long-term application of gypenosides to lipid reduction and nervous system protection, and explained why gypenosides were used to treat brain diseases, even though they had a poor ability to enter the brain. Besides, it provided a theoretical basis for clinical application of gypenosides and the development of new drugs.

Gut microbiota dependent trimethylamine N-oxide aggravates angiotensin II–induced hypertension

Gut microbiota produce Trimethylamine N-oxide (TMAO) by metabolizing dietary phosphatidylcholine, choline, l-carnitine and betaine. TMAO is implicated in the pathogenesis of chronic kidney disease (CKD), diabetes, obesity and atherosclerosis. We test, whether TMAO augments angiotensin II (Ang II)-induced vasoconstriction and hence promotes Ang II-induced hypertension. Plasma TMAO levels were indeed elevated in hypertensive patients, thus the potential pathways by which TMAO mediates these effects were explored. Ang II (400 ng/kg−1min−1) was chronically infused for 14 days via osmotic minipumps in C57Bl/6 mice. TMAO (1%) or antibiotics were given via drinking water. Vasoconstriction of renal afferent arterioles and mesenteric arteries were assessed by microperfusion and wire myograph, respectively. In Ang II-induced hypertensive mice, TMAO elevated systolic blood pressure and caused vasoconstriction, which was alleviated by antibiotics. TMAO enhanced the Ang II-induced acute pressor responses (12.2 ± 1.9 versus 20.6 ± 1.4 mmHg; P < 0.05) and vasoconstriction (32.3 ± 2.6 versus 55.9 ± 7.0%, P < 0.001). Ang II-induced intracellular Ca2+ release in afferent arterioles (147 ± 7 versus 234 ± 26%; P < 0.001) and mouse vascular smooth muscle cells (VSMC, 123 ± 3 versus 157 ± 9%; P < 0.001) increased by TMAO treatment. Preincubation of VSMC with TMAO activated the PERK/ROS/CaMKII/PLCβ3 pathway. Pharmacological inhibition of PERK, ROS, CaMKII and PLCβ3 impaired the effect of TMAO on Ca2+ release. Thus, TMAO facilitates Ang II-induced vasoconstriction, thereby promoting Ang II-induced hypertension, which involves the PERK/ROS/CaMKII/PLCβ3 axis.

Resistant Starch Type-2 Supplementation Does Not Decrease Trimethylamine N-Oxide (TMAO) Plasma Level in Hemodialysis Patients

Purpose: Dysbiosis is recognized as a new cardiovascular disease (CVD) risk factor in hemodialysis (HD) patients because it is linked to increased generation in the gut of uremic toxins such as trimethylamine N-Oxide (TMAO) from dietary precursors (choline, betaine, or L-carnitine). Nutritional strategies have been proposed to modulate the gut microbiota and reduce the production of these toxins. This study aimed to evaluate the effect of amylose-resistant starch (RS) supplementation on TMAO plasma levels in HD patients. Methods: We conducted a randomized, double-blind, placebo-controlled trial (NCT02706808) with patients undergoing HD enrolled in a previous pilot study. The participants were allocated to RS or placebo groups to receive 16 g/d of RS or placebo for 4 weeks. Plasma TMAO, choline, and betaine levels were measured with LC-MS/MS. Fecal microbiome composition was evaluated by 16S ribosomal RNA sequencing, followed by a search for TMA-associated taxa. Anthropometric, routine biochemical parameters, and food intake were evaluated. Results: Twenty-five participants finished the study, 13 in the RS group, and 12 in the placebo group. RS supplementation did not reduce TMAO plasma levels. Moreover, no significant alterations were observed in choline, betaine, anthropometric, biochemical parameters, or food intake in both groups. Likewise, RS was not found to exert any influence on the proportion of potential TMA-producing bacterial taxa in fecal matter. Conclusion: RS supplementation did not influence plasma TMAO, choline, betaine, or fecal taxa potentially linked to TMAO. Thus, RS does not seem to modify the TMA-associated bacterial taxa, precursors of TMAO. Supplemental data for this article is available online at https://doi.org/10.1080/07315724.2021.1967814 .

Fasting and postprandial trimethylamine N-oxide in sedentary and endurance-trained males following a short-term high-fat diet.

Gut bacteria release trimethylamine (TMA) from dietary substrates. TMA is absorbed and is subsequently oxidized in the liver to produce trimethylamine N‐oxide (TMAO). Plasma TMAO levels are positively correlated with risk for type 2 diabetes (T2D) and cardiovascular disease (CVD). High‐fat diet (HFD) consumption has been reported to increase fasting and postprandial TMAO in sedentary individuals. However, whether the increase in TMAO with consumption of an HFD is observed in endurance‐trained males is unknown. Healthy, sedentary (n = 17), and endurance‐trained (n = 7) males consumed a 10‐day eucaloric diet comprised of 55% carbohydrate, 30% total fat, and <10% saturated fat prior to baseline testing. Blood samples were obtained in a fasted state and for a 4‐hour high‐fat challenge (HFC) meal at baseline and then again following 5‐day HFD (30% carbohydrate, 55% total fat, and 25% saturated fat). Plasma TMAO and TMA‐moiety (choline, betaine, L‐carnitine) concentrations were measured using isocratic ultraperformance liquid chromatography‐tandem mass spectrometry. Age (23 ±3 vs. 22 ± 2 years) and body mass index (23.0 ± 3.0 vs. 23.5 ± 2.1 kg/m2) were similar (both p > 0.05) in the sedentary and endurance‐trained group, respectively. VO2max was significantly higher in the endurance‐trained compared with sedentary males (56.7 ± 8.2 vs. 39.9 ± 6.0 ml/kg/min). Neither the HFC nor the HFD evoked a detectable change in plasma TMAO (p > 0.05) in either group. Future studies are needed to identify the effects of endurance training on TMAO production.

Plasm trimethylamine-N-oxide level and association with lesion severity in coronary heart disease patients with type 2 diabetes mellitus

Objective: To investigate the association between trimethylamine-N-oxide (TMAO) and the degree of coronary atherosclerosis in coronary heart diseases (CHD) patients with type 2 diabetes mellitus. Methods: Consecutive patients, who underwent coronary angiography due to suspected CHD in Beijing Hospital from November 2016 to January 2018, were screened in this cross-sectional study. According to blood glucose level, previous medical history and coronary angiography results, they were divided into CHD without type2 diabetes mellitus(CHD-nDM) group and CHD with type2 diabetes mellitus(CHD-DM) group. Plasma TMAO levels in each group were measured by LC-MS/MS. Spearman correlation analysis was used to evaluate the correlation between TMAO and the number of diseased vessels and Gensini scores. Multivariate logistic regression was used to analyze the correlation between TMAO and high Gensini scores. Results: A total of 590 patients were enrolled in the study, including 238 patients in CHD-DM group and 352 patients in CHD-nDM group. Patients were older, body mass index, blood pressure level, prevalence of history of hypertension and statins use were higher in CHD-DM group than in CHD-nDM group (all P<0.05). The proportion of patients with multivessel disease (2 or more vessels) was also higher in CHD-DM group than in CHD-nDM group (P<0.001). Gensini score was higher in CHD-DM group than in CHD-nDM group (P<0.05). Fasting blood glucose, glycosylated hemoglobin and urea were significantly higher, while low-density lipoprotein cholesterol and hemoglobin were significantly lower in CHD-DM group than in CHD-nDM group (all P<0.05). The levels of TMAO was significantly higher in CHD-DM group than in CHD-nDM group (P<0.001). Spearman correlation analysis showed that TMAO was positively correlated with the number of diseased vessels, Gensini score, age and blood glucose level (r=0.178, 0.189, 0.260, 0.111, respectively, all P<0.01). Multivariate logistic regression analysis showed that, TMAO level was still positively correlated with high Gensini score in CHD-DM group (OR=2.25, 95%CI 1.16-4.38, P=0.017), but not in CHD-nDM group (OR=1.29, 95%CI 0.72-2.31, P=0.386) after adjusting for age, sex, body mass index, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, total cholesterol, triglyceride, history of hypertension, hyperlipidemia, smoking and statin use. Conclusions: In CHD patients with tupe 2 diabetes mellitus, the plasma TMAO level is significantly increased and is independent and positively correlated with the degree of coronary artery disease.

Gut microbiota-generated metabolite, trimethylamine-N-oxide, and subclinical myocardial damage: a multicenter study from Thailand

Plasma Trimethylamine-N-oxide (TMAO), a gut microbiota metabolite from dietary phosphatidylcholine, is mechanistically linked to cardiovascular disease (CVD) and adverse cardiovascular events. We aimed to examine the relationship between plasma TMAO levels and subclinical myocardial damage using high-sensitivity cardiac troponin-T (hs-cTnT). We studied 134 patients for whom TMAO data were available from the Cohort Of patients at a high Risk of Cardiovascular Events—Thailand (CORE-Thailand) registry, including 123 (92%) patients with established atherosclerotic disease and 11 (8%) with multiple risk factors. Plasma TMAO was measured by NMR spectroscopy. In our study cohort (mean age 64 ± 8.9 years; 61% men), median TMAO was 3.81 μM (interquartile range [IQR] 2.89–5.50 μM), and median hs-cTnT was 15.65 ng/L (IQR 10.17–26.67). Older patients and those with diabetic or hypertension were more likely to have higher TMAO levels. Plasma TMAO levels correlated with those of hs-cTnT (r = 0.54; p < 0.0001) and were significantly higher in patients with subclinical myocardial damage (hs-cTnT ≥ 14 ng/L; 4.48 μM vs 2.98 μM p < 0.0001). After adjusting for traditional risk factors, elevated TMAO levels remained independently associated with subclinical myocardial damage (adjusted odds ratio [OR]: 1.58; 95% CI 1.24–2.08; p = 0.0007). This study demonstrated that plasma TMAO was an independent predictor for subclinical myocardial damage in this study population.

FMO3-TMAO axis modulates the clinical outcome in chronic heart-failure patients with reduced ejection fraction: evidence from an Asian population.

The association among plasma trimethylamine-N-oxide (TMAO), FMO3 polymorphisms, and chronic heart failure (CHF) remains to be elucidated. TMAO is a microbiota-dependent metabolite from dietary choline and carnitine. A prospective study was performed including 955 consecutively diagnosed CHF patients with reduced ejection fraction, with the longest follow-up of 7 years. The concentrations of plasma TMAO and its precursors, namely, choline and carnitine, were determined by liquid chromatography-mass spectrometry, and the FMO3 E158K polymorphisms (rs2266782) were genotyped. The top tertile of plasma TMAO was associated with a significant increment in hazard ratio (HR) for the composite outcome of cardiovascular death or heart transplantation (HR = 1.47, 95% CI = 1.13-1.91, P = 0.004) compared with the lowest tertile. After adjustments of the potential confounders, higher TMAO could still be used to predict the risk of the primary endpoint (adjusted HR = 1.33, 95% CI = 1.01-1.74, P = 0.039). This result was also obtained after further adjustment for carnitine (adjusted HR = 1.33, 95% CI = 1.01-1.74, P = 0.039). The FMO3 rs2266782 polymorphism was associated with the plasma TMAO concentrations in our cohort, and lower TMAO levels were found in the AA-genotype. Thus, higher plasma TMAO levels indicated increased risk of the composite outcome of cardiovascular death or heart transplantation independent of potential confounders, and the FMO3 AA-genotype in rs2266782 was related to lower plasma TMAO levels.

Trimethylamine N-Oxide Exacerbates Renal Inflammation and Fibrosis in Rats With Diabetic Kidney Disease.

The gut microbiota plays a pivotal role in the onset and development of diabetes and its complications. Trimethylamine N-oxide (TMAO), a gut microbiota-dependent metabolite of certain nutrients, is associated with type 2 diabetes and its complications. Diabetic kidney disease (DKD) is one of the most serious microvascular complications. However, whether TMAO accelerates the development of DKD remains unclear. We tested the hypothesis that TMAO accelerates the development of DKD. A high-fat diet/low-dose streptozotocin-induced diabetes rat model was established, with or without TMAO in the rats’ drinking water. Compared to the normal rats, the DKD rats showed significantly higher plasma TMAO levels at the end of the study. TMAO treatment not only exacerbated the kidney dysfunction of the DKD rats, but also renal fibrosis. Furthermore, TMAO treatment activated the nucleotide-binding domain, leucine-rich-containing family, pyrin domain-containing-3 (NLRP3) inflammasome and resulted in the release of interleukin (IL)-1β and IL-18 to accelerate renal inflammation. These results suggested that TMAO aggravated renal inflammation and fibrosis in the DKD rats, which provides a new perspective to understand the pathogenesis of DKD and a potential novel target for preventing the progression of DKD.

942-P: The Choline Metabolite TMAO Inhibits NETosis and Promotes Placental Development in GDM of Humans and Mice

Objective: Trimethylamine N-oxide (TMAO) is a choline metabolite and has been reported as a risk factor of gestational diabetes mellitus (GDM). Diabetes primes neutrophils to produce neutrophil extracellular traps (NETosis). We investigated the effect of TMAO and NETs on the placenta and revealed the role of TMAO and NETs in GDM. Methods: Peripheral plasma, cord plasma and placenta from normal pregnant and GDM women were collected. Plasma concentrations of TMAO, ds-DNA and myeloperoxidase (MPO) were compared and association analysis was performed. HTR-8/Svneo cells and GDM models of wild-type and PAD4-/- mice were used to observe the effect of TMAO and NETs on the placenta. Results: The peripheral and cord plasma TMAO levels of GDM women were significantly higher than those of control. BMI and glucose levels were positively correlated with the concentration of blood TMAO, especially the newborn weight and placental thickness were positively correlated with TMAO levels in cord blood. TMAO could promote proliferation, migration, invasion and angiogenesis of HTR-8/Svneo cells, and TMAO-treated neutrophils could resist NETosis stimulated by PMA or LPS. Plasma concentrations of ds-DNA and MPO in peripheral and cord blood were significantly higher in GDM women, and BMI and blood glucose levels were positively correlated with ds-DNA and MPO levels. MPO levels from GDM placenta were also higher than those in the control group. NETs inhibit the proliferation, migration, invasion and angiogenesis of HTR-8/Svneo cells. The placenta weight of PAD4-/- mice was significantly higher than that of wild-type mice. TMAO feeding also significantly increased the weight of the placenta and fetuses, and this increase did not affect the normal structure of the placenta. Conclusion: Higher TMAO levels and abnormal NETosis were associated with GDM. TMAO could not only promote the development of the placenta and fetus, but also inhibit NETosis to protect the placenta. Disclosure X. Lin: None. Y. Zhang: None. X. He: None. N. Chen: None. M. Wang: None. Y. Chen: None. X. Xiao: None. Funding National Natural Science Foundation of China (82071734, 81871222)

MO977POTENTIAL INTERACTIONS BETWEEN UREMIC TOXINS AND DRUGS: AN APPLICATION IN KIDNEY TRANSPLANT RECIPIENTS TREATED WITH CALCINEURIN INHIBITORS*

Abstract Background and Aims In addition to affecting glomerular filtration rate, chronic kidney disease (CKD) changes the absorption, distribution and nonrenal clearance of a number of drugs. The uremic toxins that accumulate with as renal function deteriorates can potentially affect drug pharmacokinetics. Given the requirement for therapeutic drug monitoring (TDM) with most immunosuppressants, the latter are good models for understanding the potential impact of uremic toxins on blood concentrations of drugs. We focused on two calcineurin inhibitors (tacrolimus and cyclosporine) with similar pharmacological properties: low but variable oral bioavailability, strong binding to plasma proteins (albumin for tacrolimus and lipoproteins for cyclosporine), metabolism by cytochrome P450 3A4/5, and excretion in the bile. Our starting hypothesis was that uremic toxins influence the exposure of immunosuppressants. The study’s objective was to determine whether plasma concentrations of certain uremic toxins were correlated with blood concentrations of the two immunosuppressants. Method DRUGTOX was a cross-sectional study of 403 adult patients followed up after kidney transplantation at Amiens University Medical Center (Amiens, France) and who had undergone TDM of calcineurin inhibitors between August 4th, 2019, and March 11th, 2020. The patients had been treated daily with oral tacrolimus or cyclosporine. Two groups were constituted: 203 patients with low uremic toxin levels (estimated glomerular filtration rate (eGFR) according to the Modification of Diet in Renal Disease equation &amp;gt;40 mL/min/1.73m2) and 200 patients with high uremic toxin levels (eGFR &amp;lt;40 mL/min/1.73m2). For each patient, immunosuppressant trough concentrations (C0) were measured in whole-blood samples and then normalized against the total daily dose: C0/D ratio. After centrifugation, the sample was assayed for five uremic toxins (urea, trimethylamine N-oxide (TMAO), indole acetic acid (IAA), para-cresylsulfate (PCS), and indoxylsulfate (IxS)) using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Univariate and multivariate logistic regressions were used to evaluate the associations between plasma uremic toxin levels and the blood tacrolimus or cyclosporine C0/D ratio. Results The median [interquartile range] age was 56 [48-66] and the median eGFR was 41 [30-57] ml/min/1.73 m2. The majority of the patients (56.5%) were at CKD stage 3. A total of 248 (61.5%) patients were being treated with tacrolimus and 155 (38.5%) were being treated with cyclosporine. The median time between transplantation and study inclusion was 6.5 years. Plasma urea, TMAO, IAA, PCS and IxS levels rose progressively with the CKD stage. In a univariate logistic analysis, age, sex, BMI, urea, IxS and PCS were significantly associated with an increment in the tacrolimus C0/D ratio. A multivariate analysis revealed an independent association with IxS (odds ratio [95% confidence interval]: 1.36 [1.00; 1.85], after adjustment for sex, age and BMI, whereas adjustment for age weakened the association for PCS (OR: 1.22 (0.99; 1.55)) and urea (OR: 1.71 (0.93; 3.16)). In a univariate logistic analysis, age, sex, BMI, and the TMAO level (but neither PCS, IxS, IAA nor urea) were significantly associated with an increment in the cyclosporine C0/D ratio. Conclusion Even though TDM and dose adaptation of immunosuppressants keeps levels within the therapeutic window, elevated exposure to tacrolimus (but not cyclosporine) is associated with an accumulation of PCS, IxS and urea. This might be explained by an interaction between tacrolimus and highly albumin-bound uremic toxins. Our findings may have implications for other drugs that bind with high affinity to albumin (since an elevated free fraction might lead to unexpected exposures, which can alter their efficacy and/or tolerance).

Association of Urinary and Plasma Levels of Trimethylamine N-Oxide (TMAO) with Foods.

Introduction: Trimethylamine N-oxide (TMAO) may play a key mediator role in the relationship between the diet, gut microbiota and cardiovascular diseases, particularly in people with kidney failure. The aim of this review is to evaluate which foods have a greater influence on blood or urinary trimethylamine N-oxide (TMAO) levels. Methods: 391 language articles were screened, and 27 were analysed and summarized for this review, using the keywords “TMAO” AND “egg” OR “meat” OR “fish” OR “dairy” OR “vegetables” OR “fruit” OR “food” in December 2020. Results: A strong correlation between TMAO and fish consumption, mainly saltwater fish and shellfish, but not freshwater fish, has been demonstrated. Associations of the consumption of eggs, dairy and meat with TMAO are less clear and may depend on other factors such as microbiota or cooking methods. Plant-based foods do not seem to influence TMAO but have been less investigated. Discussion: Consumption of saltwater fish, dark meat fish and shellfish seems to be associated with an increase in urine or plasma TMAO values. Further studies are needed to understand the relationship between increased risk of cardiovascular disease and plasma levels of TMAO due to fish consumption. Interventions coupled with long-term dietary patterns targeting the gut microbiota seem promising.

Dietary Choline Supplements, but Not Eggs, Raise Fasting TMAO Levels in Participants with Normal Renal Function: A Randomized Clinical Trial

BackgroundCholine is a dietary precursor to the gut microbial generation of the prothrombotic and proatherogenic metabolite trimethylamine-N-oxide (TMAO). Eggs are rich in choline, yet the impact of habitual egg consumption on TMAO levels and platelet function in human subjects remains unclear. MethodsHealthy volunteers (41% male, 81% Caucasian, median age 28 years) with normal renal function (estimated glomerular filtration rate >60) were recruited and assigned to 1 of 5 daily interventions for 4 weeks: 1) hardboiled eggs (n = 18); 2) choline bitartrate supplements (n = 20); 3) hardboiled eggs + choline bitartrate supplements (n = 16); 4) egg whites + choline bitartrate supplements (n = 18); 5) phosphatidylcholine supplements (n = 10). Fasting blood and urine samples were collected for quantification of TMAO, its precursors, and platelet aggregometry. ResultsParticipants’ plasma TMAO levels increased significantly in all 3 intervention arms containing choline bitartrate (all P < .0001), but daily ingestion of 4 large eggs (P = .28) or phosphatidylcholine supplements (P = .27) failed to increase plasma TMAO levels. Platelet reactivity also significantly increased in the 3 intervention arms containing choline bitartrate (all P < .01), but not with eggs (P = .10) or phosphatidylcholine supplements (P = .79). ConclusionsDespite high choline content in egg yolks, healthy participants consuming 4 eggs daily showed no significant increase in TMAO or platelet reactivity. However, choline bitartrate supplements providing comparable total choline raised both TMAO and platelet reactivity, demonstrating that the form and source of dietary choline differentially contributes to systemic TMAO levels and platelet responsiveness.

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.