Trimethylamine N-oxide Concentrations Research Articles

Development of a novel method for the simultaneous detection of trimethylamine N-oxide and creatinine in the saliva of patients with chronic kidney disease – Its utility in saliva as an alternative to blood

Chronic kidney disease (CKD) is associated with increased levels of creatinine and other uremic toxins (UTs), which impaired kidneys cannot filtrate. Typically, CKD is diagnosed by calculating the estimated glomerular filtration rate using serum creatinine or cystatin C levels. In pursuit of more sensitive and reliable biomarkers of kidney dysfunction, scientific attention has turned towards other UTs, such as trimethylamine N-oxide (TMAO), successfully quantified in standard matrices, blood and urine. However, less invasive monitoring of kidney function can be performed using an alternative diagnostic biofluid, saliva, which has been shown to contain clinically relevant concentrations of renal function markers. Accurate quantitative estimation of serum biomarkers using saliva measurements can only be achieved provided that there is a tight saliva-serum correlation for the analyte of interest. Therefore, we aimed to verify the correlation between saliva and serum levels of TMAO in CKD patients using newly developed and validated quantitative liquid chromatography coupled to mass spectrometry (LC-MS) method for simultaneous detection of TMAO, and creatinine – the conventional marker of renal impairment. Secondly, we applied this method to quantify TMAO and creatinine levels in the resting saliva of CKD patients collected with a standardised method involving swab-based collectors. A good linear correlation was obtained between the concentration of creatinine in serum and resting saliva of CKD patients (r = 0.72, p = 0.029) and even better in the case of TMAO (r = 0.81, p = 0.008). The analysed validation criteria were fulfilled. No significant influence of the type of swab in the Salivette® device on creatinine and TMAO concentrations in saliva was detected. Our study indicates that saliva can be successfully used in the non-invasive monitoring of renal failure in CKD by measuring salivary TMAO concentrations.

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.

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.

Regular Consumption of Cocoa and Red Berries as a Strategy to Improve Cardiovascular Biomarkers via Modulation of Microbiota Metabolism in Healthy Aging Adults.

The aim of the present study was to analyze the effects of cocoa flavanols and red berry anthocyanins on cardiovascular biomarkers, such as homocysteine, angiotensin-converting enzyme (ACE), nitric oxide (NO), flow-mediated vasodilation (FMD), blood pressure and lipid profile. Additionally, we aimed to ascertain their possible interactions with microbiota related metabolites, such as secondary bile acids (SBA), short-chain fatty acids (SCFA) and trimethylamine N-oxide (TMAO). A randomized, parallel-group study, single-blind for the research team, was performed on 60 healthy volunteers between the ages of 45 and 85, who consumed 2.5 g/day of cocoa powder (9.59 mg/day of total flavanols), 5 g/day of a red berry mixture (13.9 mg/day of total anthocyanins) or 7.5 g/day of a combination of both for 12 weeks. The group that had consumed cocoa showed a significant reduction in TMAO (p = 0.03) and uric acid (p = 0.01) levels in serum, accompanied by an increase in FMD values (p = 0.03) and total polyphenols. corrected by creatinine (p = 0.03) after the intervention. These latter values negatively correlated with the TMAO concentration (R = -0.57, p = 0.02). Additionally, we observed an increase in carbohydrate fermentation in the groups that had consumed cocoa (p = 0.04) and red berries (p = 0.04) between the beginning and the end of the intervention. This increase in carbohydrate fermentation was correlated with lower levels of TC/HDL ratio (p = 0.01), systolic (p = 0.01) and diastolic blood pressure (p = 0.01). In conclusion, our study showed a positive modulation of microbiota metabolism after a regular intake of cocoa flavanols and red berry anthocyanins that led to an improvement in cardiovascular function, especially in the group that consumed cocoa.

Trimethylamine N-Oxide Exacerbates Neuroinflammation and Motor Dysfunction in an Acute MPTP Mice Model of Parkinson's Disease.

Observational studies have shown abnormal changes in trimethylamine N-oxide (TMAO) levels in the peripheral circulatory system of Parkinson's disease (PD) patients. TMAO is a gut microbiota metabolite that can cross the blood-brain barrier and is strongly related to neuroinflammation. Neuroinflammation is one of the pathological drivers of PD. Herein, we investigated the effect of TMAO on 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD model mice. TMAO pretreatment was given by adding 1.5% (w/v) TMAO to the drinking water of the mice for 21 days; then, the mice were administered MPTP (20 mg/kg, i.p.) four times a day to construct an acute PD model. Their serum TMAO concentrations, motor function, dopaminergic network integrity, and neuroinflammation were then assayed. The results showed that TMAO partly aggravated the motor dysfunction of the PD mice. Although TMAO had no effect on the dopaminergic neurons, TH protein content, and striatal DA level in the PD mice, it significantly reduced the striatal 5-HT levels and aggravated the metabolism of DA and 5-HT. Meanwhile, TMAO significantly activated glial cells in the striatum and the hippocampi of the PD mice and promoted the release of inflammatory cytokines in the hippocampus. In summary, higher-circulating TMAO had adverse effects on the motor capacity, striatum neurotransmitters, and striatal and hippocampal neuroinflammation in PD mice.

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.

TMAO: Protecting proteins from feeling the heat

Osmolytes are ubiquitous in the cell and play an important role in controlling protein stability under stress. The natural osmolyte trimethylamine N-oxide (TMAO) is used by marine animals to counteract the effect of pressure denaturation at large depths. The molecular mechanism of TMAO stabilization against pressure and urea denaturation has been extensively studied, but unlike the case of other osmolytes, the ability of TMAO to protect proteins from high temperature has not been quantified. To reveal the effect of TMAO on folded and unfolded protein ensembles and the hydration shell at different temperatures, we study a mutant of the well-characterized, fast-folding model protein B (PRB). We carried out, in total, >190 μs all-atom simulations of thermal folding/unfolding of PRB at multiple temperatures and concentrations of TMAO. The simulations show increased thermal stability of PRB in the presence of TMAO. Partly structured, compact ensembles are favored over the unfolded state. TMAO forms two shells near the protein: an outer shell away from the protein surface has altered H-bond lifetimes of water molecules and increases hydration of the protein to help stabilize it; a less-populated inner shell with an opposite TMAO orientation closer to the protein surface binds exclusively to basic side chains. The cooperative cosolute effect of the inner and outer shell TMAO has a small number of TMAO molecules “herding” water molecules into two hydration shells at or near the protein surface. The stabilizing effect of TMAO on our protein saturates at 1 M despite higher TMAO solubility, so there may be little evolutionary pressure for extremophiles to produce higher intracellular TMAO concentrations, if true in general.

Gut microbiota-derived metabolite trimethylamine N-oxide and biomarkers of inflammation are linked to endothelial and coronary microvascular function in patients with inflammatory bowel disease.

Inflammatory bowel disease (IBD), which is an umbrella term used for ulcerative colitis (UC) and Crohn's disease (CD), is associated with an increased risk for atherosclerotic cardiovascular disease (CVD). We aimed to investigate the association of local and systemic biomarkers of inflammation and gut microbiota-derived metabolite trimethylamine N-oxide (TMAO) with endothelial and coronary microvascular dysfunction in IBD. A total of 56 patients with IBD (20 with UC and 36 with CD) and 34 age and gender matched controls were included. For all participants, samples were collected to analyze faecal calprotectin, and TMAO concentrations. Ultrasound-based examinations were done to measure flow-mediated vasodilatation (FMD) and coronary flow velocity reserve (CFVR). Patients with IBD had lower CFVR (2.07 (1.82-2.40)) and FMD (8.7±3.7) as compared to controls (2.30 (2.07-2.74), p=0.005 and 11.9±6.8, p=0.03). In patients with IBD, TMAO concentration (r=-0.30, p=0.03), C-reactive protein (r=-0.29, p=0.03) and WBC count (r=-0.37, p=0.006) had a significant negative correlation with CFVR, and TMAO (β=-0.27, 95% CI: -0.23 to -0.02) and WBC count (β=-0.31, 95% CI: -0.56 to -0.06) were significant predictors of CFVR after multivariate adjustment. None of the biomarkers of inflammation or TMAO showed significant correlations with FMD. In patients with UC, TMAO showed a significant correlation with both CFVR (r=-0.55, p=0.01) and FMD (r=-0.60, p=0.005) while only WBC count had a statistically significant correlation with CFVR (r=-0.49, p=0.004) in patients with CD. Gut microbiota-derived metabolite TMAO and biomarkers of systemic inflammation are associated with measures of endothelial/coronary microvascular dysfunction in patients with IBD.

Prognostic value of gut microbiota-derived trimethylamine N-oxide in patients with ischemic stroke: A meta-analysis

Objective: This study aimed to evaluate the relationship between the intestinal microbial metabolite trimethylamine N-oxide (TMAO) level in the plasma and the outcomes of patients with ischemic stroke (IS). Methods: The PubMed, Web of Science, Cochrane Library, and Embase databases were systematically searched until July 1, 2022 to identify clinical studies on TMAO levels and prognosis of IS. The identified studies were then screened according to the inclusion and exclusion criteria, and a meta-analysis on the final included studies was performed using the Stata (version 17.0) software to investigate the effects of TMAO level on the prognosis of IS. Results: Four studies involving 1,026 participants from 2019 to 2022 were considered. The results indicated an association between high circulating TMAO concentration and poor functional outcomes (rate ratio [RR]: 2.76; 95% confidence interval [CI]:1.33,5.72; P = 0.006; I2 = 72.7%; P-heterogeneity = 0.012; random-effects model), mortality (RR: 5.37; 95%CI: 2.63,10.97; P &lt; 0.001; I2 = 0.0%; P-heterogeneity = 0.704; fixed-effects model), and recursive ischemic events (RR: 2.71; 95%CI: 1.68,4.36; P &lt; 0.001; I2 = 0.0%; P heterogeneity = 0.779; fixed-effects model) 3 months after IS. Conclusions: Elevated TMAO level may be an adverse prognostic indicator in patients with IS.

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.

Correlation between Saliva Levels and Serum Levels of Free Uremic Toxins in Healthy Volunteers

The objective of the present study was to investigate the putative correlation between the saliva concentration and free serum concentration for 10 uremic toxins (UTs; eight protein-bound solutes: 3-carboxy-4-methyl-5-propyl-2-furanpropanoic acid (CMPF), hippuric acid (HA), indole-3-acetic acid (3-IAA), indoxyl sulfate (I3S), kynurenic acid (KA), kynurenine (KYN), p-cresyl glucuronide (pCG), and p-cresyl sulfate (pCS); two free, water-soluble, low-molecular weight solutes: phenylacetylglutamine (PAGN) and trimethylamine N-oxide (TMAO); and three precursors: tyrosine (Tyr), phenylalanine, and tryptophan). Saliva samples and blood samples were collected simultaneously from 18 healthy volunteers. After the addition of internal standards, 50 µL of saliva or serum were precipitated with methanol. UTs and precursors were quantified using a validated LC-MS/MS method. The saliva-serum correlation was statistically significant (according to Spearman's coefficient) for six UTs (TMAO, HA, I3S, pCS, 3-IAA, and CMPF). Tyr presented a weak saliva-serum correlation (p = 0.08), whereas the other two precursors did not show a saliva-serum correlation. For three UTs (KYN, KA and pCG), we were unable to test the correlation since the saliva or serum levels were too low in many of the volunteers. The present study is the first to report on the saliva concentrations of TMAO, KYN, HA, PAGN, pCG, and 3-IAA.

Trimethylamine N-Oxide and Related Metabolites in the Serum and Risk of Type 2 Diabetes in the Chinese Population: A Case-Control Study.

Trimethylamine N-oxide (TMAO) and its precursors have an association with type 2 diabetes mellitus (T2DM); however, the evidence is unclear. The current study examined the association of serial measures of serum TMAO and related metabolite concentrations with the risk of T2DM. Our study was designed as a community case-control study with 300 participants (150 T2DM and 150 non-T2DM). We examined the association of serum concentrations of TMAO and its related metabolites [trimethylamine, choline, betaine, and L-carnitine] using UPLC-MS/MS. The association between these metabolites and the risk of T2DM was analyzed using a restricted cubic spline and binary logistic regression. A higher serum choline concentration was significantly associated with an increased risk of T2DM. Serum choline > 22.62 μmol/L was independently associated with an increased risk of T2DM, and the odds ratio was 3.615 [95% CI: (1.453,8.993), P = 0.006]. Similarly, serum betaine and L-carnitine concentrations had a markedly decreased risk of T2DM even after adjusting for the traditional risk factors for T2DM and betaine (0.978 [95% CI:0.964-0.992], P = 0.002) and L-carnitine (0.949 [95% CI: 0.9222-0.978], P = 0.001), respectively. Choline, betaine, and L-carnitine are associated with the risk of T2DM and may be appropriate risk markers to protect high-risk individuals from T2DM.

Trimethylamine N-Oxide Response to a Mixed Macronutrient Tolerance Test in a Cohort of Healthy United States Adults.

Plasma trimethylamine n-oxide (TMAO) concentration increases in responses to feeding TMAO, choline, phosphatidylcholine, L-carnitine, and betaine but it is unknown whether concentrations change following a mixed macronutrient tolerance test (MMTT) with limited amounts of TMAO precursors. In this proof-of-concept study, we provided healthy female and male adults (n = 97) ranging in age (18-65 years) and BMI (18-44 kg/m2) a MMTT (60% fat, 25% sucrose; 42% of a standard 2000 kilo calorie diet) and recorded their metabolic response at fasting and at 30 min, 3 h, and 6 h postprandially. We quantified total exposure to TMAO (AUC-TMAO) and classified individuals by the blood draw at which they experienced their maximal TMAO concentration (TMAO-response groups). We related AUC-TMAO to the 16S rRNA microbiome, to two SNPs in the exons of the FMO3 gene (rs2266782, G>A, p.Glu158Lys; and rs2266780, A>G, p.Glu308Gly), and to a priori plasma metabolites. We observed varying TMAO responses (timing and magnitude) and identified a sex by age interaction such that AUC-TMAO increased with age in females but not in males (p-value = 0.0112). Few relationships between AUC-TMAO and the fecal microbiome and FMO3 genotype were identified. We observed a strong correlation between AUC-TMAO and TNF-α that depended on TMAO-response group. These findings promote precision nutrition and have important ramifications for the eating behavior of adults who could benefit from reducing TMAO exposure, and for understanding factors that generate plasma TMAO.

Iodomethylcholine Inhibits Trimethylamine-N-Oxide Production and Averts Maternal Chronic Kidney Disease-Programmed Offspring Hypertension.

Chronic kidney disease (CKD) affects 10% of the global population, including pregnant women. Adverse maternal conditions determine the developmental programming of many diseases later in life. We previously demonstrated that adult rat offspring born to dams with CKD developed hypertension and renal hypertrophy. Trimethylamine-N-oxide (TMAO), a uremic toxin derived from the gut microbiota, has been linked to hypertension. This study assesses the effects of TMAO inhibition by iodomethylcholine (IMC) treatment on offspring hypertension programmed by maternal CKD. Female rats were fed either a control or a 0.5% adenine diet before conception, with or without IMC treatment during pregnancy and lactation. Maternal IMC treatment averted maternal CKD-primed offspring hypertension and renal hypertrophy in 12-week-old offspring. Offspring hypertension is associated with increases in the plasma TMAO concentration and oxidative stress and shifts in gut microbiota. The beneficial effects of IMC are related to a reduction in TMAO; increases in genera Acetatifactor, Bifidobacterium, and Eubacterium; and decreases in genera Phocacecola and Bacteroides. Our findings afford insights into the targeting of the gut microbiota to deplete TMAO production, with therapeutic potential for the prevention of offspring hypertension programmed by maternal CKD, although these results still need further clinical translation.

Plasma concentration of TMAO is an independent predictor of adverse outcomes in patients after acute myocardial infarction.

Plasma concentrations of gut microbial metabolites are associated with cardiomyocyte viability and platelet reactivity. We hypothesized that increased concentrations of gut metabolites may predict major adverse cardiac and cerebrovascular events (MACCE) after acute myocardial infarction (AMI). The primary objective of this study was to evaluate the association between elevated plasma concentrations of gut metabolites and MACCE after AMI. We compared plasma concentrations of gut metabolites (trimethylamine-N-oxide (TMAO) and indoxyl sulphate (IS)) and platelet reactivity in 57 patients with AMI and 27 healthy controls. We assessed the predictive value of gut metabolites for MACCE (stroke, recurrent AMI, death) over a median of 3.5-years. The concentrations of TMAO and IS did not differ between AMI patients and controls. The concentrations of TMAO and IS were higher in patients who developed MACCE than in those who did not (p ≤ 0.015 for all). The concentration of TMAO was the only independent predictor of MACCE in a multivariate analysis (OR = 35.041, 95% CI: 1.269-967.307, p = 0.036). Patients with the concentration of TMAO and indoxyl sulphate above the cut-off value predictive of MACCE had higher platelet activity (p ≤ 0.149 for all). Increased plasma concentration of TMAO is an independent predictor of MACCE and may contribute to post-AMI cardiac dysfunction.

Effects of Trimethylamine and Trimethylamine Oxide on Human Serum Albumin Observed by Tryptophan Fluorescence and Absorbance Spectroscopies

Trimethylamine (TMA) is an aliphatic tertiary amine produced by gut microbiota, starting from dietary precursors such as L-choline, L-carnitine and betaine. TMA and its metabolite trimethylamine-N-oxide (TMAO) are elevated in the plasma of cardiovascular disease (CVD) patients. Despite extensive literature on this topic, the scientific community is still divided on which of the two molecules is responsible for the harmful effects on human health. To assess whether the plasma levels of these molecules are also modulated by interactions with macromolecules present in the plasma, the weak bonds between TMA or/and TMAO with human serum albumin (HSA) were studied via molecular docking and spectrofluorimetric assay. The impact of TMA and TMAO on HSA and low-density lipoproteins (LDL) oxidation was also evaluated. Docking analysis shows three main binding sites for TMA and two for TMAO. Spectrofluorimetric results show interactions of HSA with TMA and TMAO; a significant (p = 0.010) decrease in Trp-214 intrinsic fluorescence of HSA was measured starting from the lowest concentrations of both TMA and TMAO (3.26 nM and 29.2 nM, respectively). Furthermore, at all concentrations tested, no significant effect on the formation of carbonyls in HSA was measured (p &gt; 0.05) in the presence of TMA or TMAO. However, 28.6 mM TMAO significantly increased (p &lt; 0.05) the degree of oxidation of LDL, suggesting that TMAO has a pro-oxidant role on LDL.

342 TMAO PLASMA LEVELS PREDICT RECURRENT ISCHEMIC EVENTS IN SURVIVORS OF MYOCARDIAL INFARCTION

Abstract Background Recent studies have highlighted a direct link between dietary nutrients, microbiota and cardiovascular disease (CVD). In this context, trimethylamine-N-oxide (TMAO), a metabolite derived from the intestinal microbiota, stands out, paving its way as one of the important biomarkers associated with atherosclerosis, increased risk of CVD, recurrent events and adverse outcomes. Methods 81 patients who survived acute myocardial infarction (AMI), (both STEMI 50 / NSTEMI 31) were enrolled in this study together with 10 healthy individuals. Further, we evaluated the relationship between plasma TMAO levels and cardiovascular events during the follow-up. The measurement of plasma levels of TMAO was performed using liquid chromatography-tandem mass spectrometry (LC-MS). Results The median plasma concentration of TMAO were significantly higher in patients with AMI compared with healthy control (1.62 (1.37–2.25) µM. vs 0.55 (0.35–0.74) µM, p &amp;lt; 0.0001). During a median follow-up of 61.74 (59.34–64.24) months, 10 out of 81 patients (12.3%) had a re-infarction. Patients who had another ischemic event had higher TMAO values compared with individuals who did not (2.29 (1.60–6.49) µM vs 1.60 (1.34–2.09) µM, p = 0.026). Further, TMAO values positively correlate with CRP, a pro-inflammatory marker. However, at multivariate Cox regression analysis, plasma TMAO values were not predictive of re-infarction. Conclusions The data of our pilot study show that higher TMAO values are associated with the risk of recurrent ischemic event. A future prospective study, including larger cohort is necessary to analyze this issue.

Changes in plasma and milk choline metabolite concentrations in response to the provision of various rumen-protected choline prototypes in lactating dairy cows.

Choline feeding in the form of rumen-protected choline (RPC) has been shown to increase milk production and improve measures of metabolic health (e.g., liver triglyceride) in dairy cows. The objective was to characterize changes in plasma and milk choline and choline metabolite concentrations, including microbial-derived trimethylamine N-oxide (TMAO), in response to increasing ruminal spot-doses, different types of RPC, and ruminal stability of RPC in lactating cows. For experiment 1, 12 mid-lactation (121 ± 16.3 d in milk) Holstein cows were balanced by total plasma choline concentrations and milk yields. Cows were assigned to 1 of 3 lipid-encapsulated RPC products (main plots): prototypes P1, P2, and P3 (containing 59, 56, and 30% choline chloride, respectively). Within each main plot, cows were assigned to a sequence of doses in a 4 × 4 Latin square design: 0, 18, 36, or 54 g of choline chloride. Treatments were preconditioned with ground corn and administered as a single ruminal bolus once per experimental period 1 h postfeeding of a total mixed ration. For experiment 2, we compared a control (0 g of choline chloride) versus P2, and P4 and P5 (60 and 62% choline chloride, respectively) in a repeated 4 × 4 Latin square design. Experiment 2 followed a similar design as experiment 1 with modifications: 12 late-lactation (228 ± 7.10 d in milk) Holstein cows were used; treatments were administered as part of a premeal; and cows received a daily allowance of a total mixed ration as equal provisions every 4 h within 24 h before and after treatment. For both experiments, plasma and milk samples were collected for choline and choline metabolite quantification. Data were analyzed using a mixed model including fixed effects of treatment, period, and time. Contrast statements were used to test for linearity of dose and differences between prototypes for experiment 1 and 2, respectively. Plasma and milk TMAO concentrations increased with RPC dose (peak by h). Milk choline and betaine yields increased with RPC dose in a quadratic manner; albeit, dependent upon RPC type. Milk phosphocholine (PCho) and glycerophosphorylcholine (GPC) yields changed by select RPC dose (experiment 1), however Met, PCho, GPC, phosphatidylcholine, and total choline concentrations in milk, and plasma Met and sphingomyelin concentrations were not responsive. We conclude that plasma or milk choline, betaine, and TMAO concentrations are responsive to RPC type, dose, and stage of lactation evaluated.

A red wine intervention does not modify plasma trimethylamine N-oxide but is associated with broad shifts in the plasma metabolome and gut microbiota composition

Gut microbiota profiles are closely related to cardiovascular diseases through mechanisms that include the reported deleterious effects of metabolites, such as trimethylamine N-oxide (TMAO), which have been studied as diagnostic and therapeutic targets. Moderate red wine (RW) consumption is reportedly cardioprotective, possibly by affecting the gut microbiota. To investigate the effects of RW consumption on the gut microbiota, plasma TMAO, and the plasma metabolome in men with documented coronary artery disease (CAD) using a multiomics assessment in a crossover trial. We conducted a randomized, crossover, controlled trial involving 42 men (average age, 60 y) with documented CAD comparing 3-wk RW consumption (250mL/d, 5 d/wk) with an equal period of alcohol abstention, both preceded by a 2-wk washout period. The gut microbiota was analyzed via 16S rRNA high-throughput sequencing. Plasma TMAO was evaluated by LC-MS/MS. The plasma metabolome of 20 randomly selected participants was evaluated by ultra-high-performance LC-MS/MS. The effect of RW consumption was assessed by individual comparisons using paired tests during the abstention and RW periods. Plasma TMAO did not differ between RW intervention and alcohol abstention, and TMAO concentrations showed low intraindividual concordance over time, with an intraclass correlation coefficient of 0.049 during the control period. After RW consumption, there was significant remodeling of the gut microbiota, with a difference in β diversity and predominance of Parasutterella, Ruminococcaceae, several Bacteroides species, and Prevotella. Plasma metabolomic analysis revealed significant changes in metabolites after RW consumption, consistent with improved redox homeostasis. Modulation of the gut microbiota may contribute to the putative cardiovascular benefits of moderate RW consumption. The low intraindividual concordance of TMAO presents challenges regarding its role as a cardiovascular risk biomarker at the individual level. This study was registered at clinical trials.gov as NCT03232099.

Higher serum trimethylamine-N-oxide levels are associated with increased abdominal aortic calcification in hemodialysis patients

Introduction Vascular calcification (VC) is high prevalent and predicts cardiovascular mortality in dialysis patients. The mechanisms are not known clearly. Trimethylamine-N-oxide (TMAO), a gut-microbiota derivate metabolite, is also associated with cardiovascular outcomes in hemodialysis (HD) patients. This study aims to evaluate serum TMAO levels and establish their relation to VC in HD patients. Methods Serum TMAO concentrations were measured by high-performance liquid chromatography–mass spectrometry. Vascular calcification was evaluated by abdominal aortic calcification (AAC) scores. Taking the AAC score value 5.5 as the cutoff value, the participants were divided into the high AAC score group and the low AAC score group. Results A total of 184 HD patients and 39 healthy controls were enrolled in this cross-sectional study. Serum Ln(TMAO) (the natural logarithm of TMAO) concentrations were significantly higher in HD patients than that of control subjects (1.82 ± 0.62 vs. −1.60 ± 0.77, p < 0.001). Compared with the group with low AAC scores, the HD patients with high AAC scores showed significantly higher serum Ln(TMAO) levels (2.09 ± 0.55 vs. 1.67 ± 0.54, p < 0.001). In the multivariate regression analysis, serum Ln(TMAO), HD vintage, with diabetic mellitus, age and plasma intact parathyroid hormone (iPTH) were independent determinant factors for VC in HD patients. Conclusions Higher serum TMAO levels, older age, longer HD vintage, higher plasma iPTH and with diabetes mellitus were independent risk factors for VC in HD patients. The underlying mechanism deserves further investigations and the finding hints at a new target for the treatment of VC.