Longitudinal Plasma Measures of Trimethylamine N-Oxide and Risk of Atherosclerotic Cardiovascular Disease Events in Community-Based Older Adults

Colorectal Cancer in Inflammatory Bowel Disease: A Review of the Role of Gut Microbiota and Bacterial Biofilms in Disease Pathogenesis

The risk of colorectal cancer [CRC] is increased in patients with inflammatory bowel disease [IBD], particularly in extensive ulcerative colitis [UC] and Crohn's colitis. Gut microbiota have been implicated in the pathogenesis of CRC via multiple mechanisms, including the release of reactive oxygen species and genotoxins, and induction of inflammation, as well as activation of the immune response. Gut microbiota can enhance their carcinogenic and proinflammatory properties by organising into biofilms, potentially making them more resistant to the host's immune system and to antibiotics. Colonic biofilms have the capacity to invade colonic tissue and accelerate tumorigenesis in tumour-prone models of mice. In the context of IBD, the prevalence of biofilms has been estimated to be up to 95%. Although the relationship between chronic inflammation and molecular mediators that contribute to IBD-associated CRC is well established, the role of gut microbiota and biofilms in this sequence is not fully understood. Because CRC can still arise in the absence of histological inflammation, there is a growing interest in identifying chemopreventive agents against IBD-associated CRC. Commonly used in the treatment of UC, 5-aminosalicylates have antimicrobial and anticarcinogenic properties that might have a role in the chemoprevention of CRC via the inhibition or modulation of carcinogenic gut microbiota and potentially of biofilm formation. Whether biologics and other IBD-targeted therapies can decrease the progression towards dysplasia and CRC, via mechanisms independent of inflammation, is still unknown. Further research is warranted to identify potential new microbial targets in therapy for chemoprevention of dysplasia and CRC in IBD.

Gut matters in microgravity: potential link of gut microbiota and its metabolites to cardiovascular and musculoskeletal well-being

The gut microbiota and its secreted metabolites play a significant role in cardiovascular and musculoskeletal health and diseases. The dysregulation of the intestinal microbiota poses a significant threat to cardiovascular and skeletal muscle well-being. Nonetheless, the precise molecular mechanisms underlying these changes remain unclear. Furthermore, microgravity presents several challenges to cardiovascular and musculoskeletal health compromising muscle strength, endothelial dysfunction, and metabolic changes. The purpose of this review is to critically examine the role of gut microbiota metabolites on cardiovascular and skeletal muscle functions and dysfunctions. It also explores the molecular mechanisms that drive microgravity-induced deconditioning in both cardiovascular and skeletal muscle. Key findings in this review highlight that several alterations in gut microbiota and secreted metabolites in microgravity mirror characteristics seen in cardiovascular and skeletal muscle diseases. Those alterations include increased levels of Firmicutes/Bacteroidetes (F/B) ratio, elevated lipopolysaccharide levels (LPS), increased in para-cresol (p-cresol) and secondary metabolites, along with reduction in bile acids and Akkermansia muciniphila bacteria. Highlighting the potential, modulating gut microbiota in microgravity conditions could play a significant role in mitigating cardiovascular and skeletal muscle diseases not only during space flight but also in prolonged bed rest scenarios here on Earth.

Trimethylamine N-Oxide and Related Gut Microbe-Derived Metabolites and Incident Heart Failure Development in Community-Based Populations

BACKGROUND

Growing evidence indicates that trimethylamine N-oxide, a gut microbial metabolite of dietary choline and carnitine, promotes both cardiovascular disease and chronic kidney disease risk. It remains unclear how circulating concentrations of trimethylamine N-oxide and its related dietary and gut microbe-derived metabolites (choline, betaine, carnitine, γ-butyrobetaine, and crotonobetaine) affect incident heart failure (HF).

METHODS

We evaluated 11 768 participants from the Cardiovascular Health Study and the Multi-Ethnic Study of Atherosclerosis with serial measures of metabolites. Cox proportional hazard models were used to examine the associations between metabolites and incident HF, adjusted for cardiovascular disease risk factors.

RESULTS

In all, 2102 cases of HF occurred over a median follow-up of 15.9 years. After adjusting for traditional risk factors, higher concentrations of trimethylamine N-oxide (hazard ratio, 1.15 [95% CI, 1.09-1.20]; P<0.001), choline (hazard ratio, 1.44 [95% CI, 1.26-1.64]; P<0.001), and crotonobetaine (hazard ratio, 1.24 [95% CI, 1.16-1.32]; P<0.001) were associated with increased risk for incident HF. After further adjustment for renal function (potential confounder or mediator), these associations did not reach Bonferroni-corrected statistical significance (P=0.01, 0.049, and 0.006, respectively). Betaine and carnitine were nominally associated with a higher incidence of HF (P<0.05). In exploratory analyses, results were similar for subtypes of HF based on left ventricular ejection fraction, and associations appeared generally stronger among Black and Hispanic/Latino versus White adults, although there were no interactions for any metabolites with race.

CONCLUSIONS

In this pooled analysis of 2 well-phenotyped, diverse, community-based cohorts, circulating concentrations of gut microbe-derived metabolites such as trimethylamine N-oxide, choline, and crotonobetaine were independently associated with a higher risk of developing HF.

REGISTRATION

URL: https://www.clinicaltrials.gov/; Unique identifiers: NCT00005133 and NCT00005487.

α-Synuclein Overexpression and the Microbiome Shape the Gut and Brain Metabolome in Mice

Pathological forms of the protein α-synuclein contribute to a family of disorders termed synucleinopathies, which includes Parkinson's disease (PD). Most cases of PD are believed to arise from gene-environment interactions. Microbiome composition is altered in PD, and gut bacteria are causal to symptoms and pathology in animal models. To explore how the microbiome may impact PD-associated genetic risks, we quantitatively profiled nearly 630 metabolites from 26 biochemical classes in the gut, plasma, and brain of α-synuclein-overexpressing (ASO) mice with or without microbiota. We observe tissue-specific changes driven by genotype, microbiome, and their interaction. Many differentially expressed metabolites in ASO mice are also dysregulated in human PD patients, including amine oxides, bile acids and indoles. Notably, levels of the microbial metabolite trimethylamine N-oxide (TMAO) strongly correlate from the gut to the plasma to the brain, identifying a product of gene-environment interactions that may influence PD-like outcomes in mice. TMAO is elevated in the blood and cerebral spinal fluid of PD patients. These findings uncover broad metabolomic changes that are influenced by the intersection of host genetics and the microbiome in a mouse model of PD.

Unraveling interindividual variation of trimethylamine N-oxide and its precursors at the population level

Trimethylamine N-oxide (TMAO) is a circulating microbiome-derived metabolite implicated in the development of atherosclerosis and cardiovascular disease (CVD). We investigated whether plasma levels of TMAO, its precursors (betaine, carnitine, deoxycarnitine, choline), and TMAO-to-precursor ratios are associated with clinical outcomes, including CVD and mortality. This was followed by an in-depth analysis of their genetic, gut microbial, and dietary determinants. The analyses were conducted in five Dutch prospective cohort studies including 7834 individuals. To further investigate association results, Mendelian Randomization (MR) was also explored. We found only plasma choline levels (hazard ratio [HR] 1.17, [95% CI 1.07; 1.28]) and not TMAO to be associated with CVD risk. Our association analyses uncovered 10 genome-wide significant loci, including novel genomic regions for betaine (6p21.1, 6q25.3), choline (2q34, 5q31.1), and deoxycarnitine (10q21.2, 11p14.2) comprising several metabolic gene associations, for example, CPS1 or PEMT. Furthermore, our analyses uncovered 68 gut microbiota associations, mainly related to TMAO-to-precursors ratios and the Ruminococcaceae family, and 16 associations of food groups and metabolites including fish-TMAO, meat-carnitine, and plant-based food-betaine associations. No significant association was identified by the MR approach. Our analyses provide novel insights into the TMAO pathway, its determinants, and pathophysiological impact on the general population.

Sleep apnoea, gut dysbiosis and cognitive dysfunction

Sleep disorders are becoming increasingly common, and their distinct effects on physical and mental health require elaborate investigation. Gut dysbiosis (GD) has been reported in sleep-related disorders, but sleep apnoea is of particular significance because of its higher prevalence and chronicity. Cumulative evidence has suggested a link between sleep apnoea and GD. This review highlights the gut-brain communication axis that is mediated via commensal microbes and various microbiota-derived metabolites (e.g. short-chain fatty acids, lipopolysaccharide and trimethyl amine N-oxide), neurotransmitters (e.g. γ-aminobutyric acid, serotonin, glutamate and dopamine), immune cells and inflammatory mediators, as well as the vagus nerve and hypothalamic-pituitary-adrenal axis. This review also discusses the pathological role underpinning GD and altered gut bacterial populations in sleep apnoea and its related comorbid conditions, particularly cognitive dysfunction. In addition, the review examines the preclinical and clinical evidence, which suggests that prebiotics and probiotics may potentially be beneficial in sleep apnoea and its comorbidities through restoration of eubiosis or gut microbial homeostasis that regulates neural, metabolic and immune responses, as well as physiological barrier integrity via the gut-brain axis.

The Gut Microbial Metabolite Trimethylamine N -oxide, Incident CKD, and Kidney Function Decline

Key Points

In community-based US adults, higher plasma trimethylamine N -oxide levels associated with higher risk of incident CKD and greater rate of kidney function decline. Findings from our study support future clinical trials to examine whether lowering plasma trimethylamine N -oxide levels may prevent CKD development and progression.

Background

Trimethylamine N -oxide (TMAO) is a gut microbiota–derived metabolite of dietary phosphatidylcholine and carnitine. Experimentally, TMAO causes kidney injury and tubulointerstitial fibrosis. Little is known about prospective associations between TMAO and kidney outcomes, especially incident CKD. We hypothesized that higher plasma TMAO levels would be associated with higher risk of incident CKD and greater rate of kidney function decline.

Methods

We included 10,564 participants from two community-based, prospective cohorts with eGFR ≥60 ml/min per 1.73 m2 to assess incident CKD. TMAO was measured using targeted mass spectrometry at baseline and one follow-up visit. Creatinine and cystatin C were measured up to four times during follow-up and used to compute eGFR. Incident CKD was defined as an eGFR decline ≥30% from baseline and a resulting eGFR <60 ml/min per 1.73 m2. Time-varying Cox models assessed the association of serial TMAO measures with incident CKD, adjusting for sociodemographic, lifestyle, diet, and cardiovascular disease risk factors. Linear mixed models assessed the association with annualized eGFR change in 10,009 participants with at least one follow-up eGFR measure without exclusions for baseline eGFR levels.

Results

During a median follow-up of 9.4 years (interquartile range, 9.1–11.6 years), 979 incident CKD events occurred. Higher TMAO levels were associated with higher risk of incident CKD (second to fifth versus first quintile hazard ratio [95% confidence interval]=1.65 [1.22 to 2.23], 1.68 [1.26 to 2.25], 2.28 [1.72 to 3.02], and 2.24 [1.68 to 2.98], respectively) and greater annualized eGFR decline (second to fifth versus first quintile annualized eGFR change=−0.21 [−0.32 to −0.09], −0.17 [−0.29 to −0.05], −0.35 [−0.47 to −0.22], and −0.43 [−0.56 to −0.30] ml/min per 1.73 m2, respectively) with monotonic dose–response relationships. These associations were consistent across different racial/ethnic groups examined. The association with eGFR decline was similar to or larger than that seen for established CKD risk factors, including diabetes, per 10 mm Hg of higher systolic BP, per 10 years of older age, and Black race.

Conclusions

In community-based US adults, higher serial measures of plasma TMAO were associated with higher risk of incident CKD and greater annualized kidney function decline.

Gut microbiota metabolites and risk of major adverse cardiovascular events and death: A systematic review and meta-analysis

BACKGROUND

Gut microbial metabolites such as trimethylamine N-oxide (TMAO) and its precursors, namely betaine, L-carnitine, and choline, have been implicated as risk factors for cardiovascular events and mortality development. Therefore, we aim to perform a systematic review and meta-analysis to assess the validity of these associations.

METHODS

MEDLINE and Scopus were queried from their inception to August 2023 to identify studies that quantified estimates of the associations of TMAO with the development of major adverse cardiovascular events (MACE) or death. A random-effects meta-analysis was conducted to pool unadjusted or multivariable-adjusted hazard ratios (HR) and their 95% confidence intervals. The primary endpoint was the risk of MACE and all-cause death.

RESULTS

30 prospective observational studies (n = 48 968) were included in the analysis. Elevated TMAO levels were associated with a significantly greater risk of MACE and all-cause death compared to low TMAO levels (HR: 1.41, 95% CI 1.2-1.54, P < .00001, I2 = 43%) and (HR: 1.55, 95% CI 1.37-1.75, P < .00001, I2 = 46%), respectively. Furthermore, high levels of either L-carnitine or choline were found to significantly increase the risk of MACE. However, no significant difference was seen in MACE in either high or low levels of betaine.

CONCLUSION

Elevated concentrations of TMAO were associated with increased risks of MACE and all-cause mortality. High levels of L-carnitine/choline were also significantly associated with an increased risk of MACE. However, no significant difference was found between high or low levels of betaine for the outcome of MACE.

Intra-hospital variation of gut microbiota product, trimethylamine N-oxide (TMAO), predicts future major adverse cardiovascular events after myocardial infarction

OBJECTIVE

Trimethylamine N-oxide (TMAO) has been associated with atherosclerosis and poor outcome. We evaluated the prognostic impact of intra-hospital TMAO variation on patient outcome.

METHODS AND RESULTS

Blood samples from 149 patients with acute myocardial infarction (AMI) were taken on admission and discharge. Plasma TMAO was determined by HPLC-MS. The endpoint was a composite three-point MACE (major adverse cardiovascular events), including all-cause mortality, re-infarction, or heart failure (HF) development. Median TMAO concentration on admission was significantly higher than on discharge (respectively, 7.81 [3.47-19.98] vs 3.45 [2.3-4.78] μM, p < 0.001). After estimating the 3.45 μM TMAO cut-off with the analysis of the continuous hazard ratio, we divided our cohort into two groups. The first group included 75 (50.3%) patients whose TMAO levels remained below or decreased under cut-off (low-low/high-low; LL/HL), while the second group included 74 (49.7%) patients whose TMAO levels remained high or increased above the cut-off during hospitalisation (high-high/low-high; HH/LH). During the median 30-month follow-up, 21.5% of patients experienced the composite endpoint. At Kaplan-Meier analysis, a trend of increasing MACE risk was observed in patients in the HH/LH group (p = 0.05). At multivariable Cox analysis, patients from the HH/LH group had more than two times higher risk of MACE during the follow-up than the LL/HL group (HR = 2.15 [95% CI, 1.03-4.5], p = 0.04). Other independent predictors of MACE were older age and worse left ventricular systolic function.

CONCLUSION

In patients with AMI, permanently high or increasing TMAO levels during hospitalisation are associated with a higher risk of MACE during long-term follow-up.

Red meat intake, faecal microbiome, serum trimethylamine N-oxide and hepatic steatosis among Chinese adults

BACKGROUND AND AIMS

Emerging evidence suggests a detrimental impact of high red meat intake on hepatic steatosis. We investigated the potential interplay between red meat intake and gut microbiome on circulating levels of trimethylamine N-oxide (TMAO) and hepatic steatosis risk.

METHODS

This cross-sectional study was conducted in a representative sample of 754 community-dwelling adults in Huoshan, China. Diet was collected using 4 quarterly 3 consecutive 24-h dietary (12-day) recalls. We profiled faecal microbiome using 16S ribosomal RNA sequencing and quantified serum TMAO and its precursors using LC-tandem MS (n = 333). We detected hepatic steatosis by FibroScan. The adjusted odds ratios (aORs) and 95% confidence intervals (CIs) were calculated using logistic regression.

RESULTS

TMAO levels but not its precursors were positively associated with the likelihood of hepatic steatosis (aOR per 1-SD increment 1.86, 95% CI 1.04-3.32). We identified 14 bacterial genera whose abundance was associated with TMAO concentration (pFDR < .05) belonging to the phyla Firmicutes, Bacteroidetes, Actinobacteria and Proteobacteria families. Per 10 g/day increase in red meat intake was positively associated with TMAO levels among participants who had higher red meat intake (>70 g/day) and higher TMAO-predicting microbial scores (TMS, β = .045, p = .034), but not among others (pinteraction = .030). TMS significantly modified the positive association between red meat and steatosis (pinteraction = .032), with a stronger association being observed among participants with higher TMS (aOR 1.30, 95% CI 1.07-1.57).

CONCLUSIONS

The bacterial genera that predicted TMAO levels may jointly modify the association between red meat intake and TMAO levels and the subsequent risk of hepatic steatosis.

The Mediterranean Diet, Its Microbiome Connections, and Cardiovascular Health: A Narrative Review

The Mediterranean diet (MD), rich in minimally processed plant foods and in monounsaturated fats but low in saturated fats, meat, and dairy products, represents one of the most studied diets for cardiovascular health. It has been shown, from both observational and randomized controlled trials, that MD reduces body weight, improves cardiovascular disease surrogates such as waist-to-hip ratios, lipids, and inflammation markers, and even prevents the development of fatal and nonfatal cardiovascular disease, diabetes, obesity, and other diseases. However, it is unclear whether it offers cardiovascular benefits from its individual components or as a whole. Furthermore, limitations in the methodology of studies and meta-analyses have raised some concerns over its potential cardiovascular benefits. MD is also associated with characteristic changes in the intestinal microbiota, mediated through its constituents. These include increased growth of species producing short-chain fatty acids, such as Clostridium leptum and Eubacterium rectale, increased growth of Bifidobacteria, Bacteroides, and Faecalibacterium prausnitzii species, and reduced growth of Firmicutes and Blautia species. Such changes are known to be favorably associated with inflammation, oxidative status, and overall metabolic health. This review will focus on the effects of MD on cardiovascular health through its action on gut microbiota.

Research development on gut microbiota and vulnerable atherosclerotic plaque

The relationship between gut microbiota and its metabolites with cardiovascular disease (CVD) has been proven. In this review, we aim to conclude the potential mechanism of gut microbiota and its metabolites on inducing the formation of vulnerable atherosclerotic plaque, and to discuss the effect of intestinal metabolites, including trimethylamine-N-oxide (TMAO), lipopolysaccharide (LPS), phenylacetylglutamine (PAG), short-chain fatty acids (SCFAs) on plaque stability. Finally, we include the impact of gut microbiota and its metabolites on plaque stability, to propose a new therapeutic direction for coronary heart disease. Gut microbiota regulation intervenes the progress of arteriosclerosis, especially on coronary atherosclerosis, by avoiding or reducing the formation of vulnerable plaque, to lower the morbidity rate of myocardial infarction.

Choline metabolites and incident cardiovascular disease in a prospective cohort of adults: Coronary Artery Risk Development in Young Adults (CARDIA) Study

BACKGROUND

The potential role for choline metabolite trimethylamine N-oxide (TMAO) in cardiovascular disease (CVD) has garnered much attention, but there have been limited data from diverse population-based cohorts. Furthermore, few studies have included circulating choline and betaine, which can serve as precursors to TMAO and may independently influence CVD.

OBJECTIVE

We quantified prospective associations between 3 choline metabolites and 19-y incident CVD in a population-based cohort and tested effect modification of metabolite-CVD associations by kidney function.

METHODS

Data were from the Coronary Artery Risk Development in Young Adults (CARDIA) Study, a prospective cohort with recruitment from 4 US urban centers (year 0: 1985-1986, n = 5115, ages 18-30). The analytic sample included 3444 White and Black males and females, aged 33 to 45, who attended the year 15 follow-up exam and did not have prevalent CVD. TMAO, choline, and betaine were quantitated from stored plasma (-70°C) using liquid-chromatography mass-spectrometry. Nineteen-year incident CVD events (n = 221), including coronary heart disease and stroke, were identified through adjudicated hospitalization records and linkage with the National Death Register.

RESULTS

Plasma choline was positively associated with CVD in Cox proportional hazards regression analysis adjusted for demographics, health behaviors, CVD risk factors, and metabolites (hazard ratio: 1.24; 95% CI: 1.09, 1.40 per standard deviation-unit choline). TMAO and betaine were not associated with CVD in an identically adjusted analysis. There was statistical evidence for effect modification by kidney function with CVD positively associated with TMAO and negatively associated with betaine at lower values of estimated glomerular filtration rate (interaction P values: 0.0046 and 0.020, respectively).

CONCLUSIONS

Our findings are consistent with a positive association between plasma choline and incident CVD. Among participants with lower kidney function, TMAO was positively, and betaine negatively, associated with CVD. These results further our understanding of the potential role for choline metabolism on CVD risk.

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

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

Blood-Derived Lipid and Metabolite Biomarkers in Cardiovascular Research from Clinical Studies: A Recent Update

The primary prevention, early detection, and treatment of cardiovascular disease (CVD) have been long-standing scientific research goals worldwide. In the past decades, traditional blood lipid profiles have been routinely used in clinical practice to estimate the risk of CVDs such as atherosclerotic cardiovascular disease (ASCVD) and as treatment targets for the primary prevention of adverse cardiac events. These blood lipid panel tests often fail to fully predict all CVD risks and thus need to be improved. A comprehensive analysis of molecular species of lipids and metabolites (defined as lipidomics and metabolomics, respectively) can provide molecular insights into the pathophysiology of the disease and could serve as diagnostic and prognostic indicators of disease. Mass spectrometry (MS) and nuclear magnetic resonance (NMR)-based lipidomics and metabolomics analysis have been increasingly used to study the metabolic changes that occur during CVD pathogenesis. In this review, we provide an overview of various MS-based platforms and approaches that are commonly used in lipidomics and metabolomics workflows. This review summarizes the lipids and metabolites in human plasma/serum that have recently (from 2018 to December 2022) been identified as promising CVD biomarkers. In addition, this review describes the potential pathophysiological mechanisms associated with candidate CVD biomarkers. Future studies focused on these potential biomarkers and pathways will provide mechanistic clues of CVD pathogenesis and thus help with the risk assessment, diagnosis, and treatment of CVD.

Nutri-microbiome epidemiology, an emerging field to disentangle the interplay between nutrition and microbiome for human health

Diet and nutrition have a substantial impact on the human microbiome, and interact with the microbiome, especially gut microbiome, to modulate various diseases and health status. Microbiome research has also guided the nutrition field to a more integrative direction, becoming an essential component of the rising area of precision nutrition. In this review, we provide a broad insight into the interplay among diet, nutrition, microbiome, and microbial metabolites for their roles in the human health. Among the microbiome epidemiological studies regarding the associations of diet and nutrition with microbiome and its derived metabolites, we summarize those most reliable findings and highlight evidence for the relationships between diet and disease-associated microbiome and its functional readout. Then, the latest advances of the microbiome-based precision nutrition research and multidisciplinary integration are described. Finally, we discuss several outstanding challenges and opportunities in the field of nutri-microbiome epidemiology.

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

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

Expanding germ-organ theory: Understanding non-communicable diseases through enterobacterial translocation

Diverse microbial communities colonize different habitats of the human body, including gut, oral cavity, nasal cavity and tissues. These microbial communities are known as human microbiome, plays a vital role in maintaining the health. However, changes in the composition and functions of human microbiome can result in chronic low-grade inflammation, which can damage the epithelial cells and allows pathogens and their toxic metabolites to translocate into other organs such as the liver, heart, and kidneys, causing metabolic inflammation. This dysbiosis of human microbiome has been directly linked to the onset of several non-communicable diseases. Recent metabolomics studies have revealed that pathogens produce several uraemic toxins. These metabolites can serve as inter-kingdom signals, entering the circulatory system and altering host metabolism, thereby aggravating a variety of diseases. Interestingly, Enterobacteriaceae, a critical member of Proteobacteria, has been commonly associated with several non-communicable diseases, and the abundance of this family has been positively correlated with uraemic toxin production. Hence, this review provides a comprehensive overview of Enterobacterial translocation and their metabolites role in non-communicable diseases. This understanding may lead to the identification of novel biomarkers for each metabolic disease as well as the development of novel therapeutic drugs.

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

AIMS

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.

METHODS AND RESULTS

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.

CONCLUSION

Plasma TMAO levels were positively associated with mortality, especially deaths due to cardiovascular and renal disease, in a multi-ethnic US cohort.

Gut microbiota dependant trimethylamine N-oxide and hypertension

The human gut microbiota environment is constantly changing and some specific changes influence the host's metabolic, immune, and neuroendocrine functions. Emerging evidence of the gut microbiota's role in the development of cardiovascular disease (CVD) including hypertension is remarkable. There is evidence showing that alterations in the gut microbiota and especially the gut-dependant metabolite trimethylamine N-oxide is associated with hypertension. However, there is a scarcity of literature addressing the role of trimethylamine N-oxide in hypertension pathogenesis. In this review, we discuss the impact of the gut microbiota and gut microbiota dependant trimethylamine N-oxide in the pathogenesis of hypertension. We present evidence from both human and animal studies and further discuss new insights relating to potential therapies for managing hypertension by altering the gut microbiota.

Impact of Caloric Restriction and Exercise on Trimethylamine N-Oxide Metabolism in Women with Obesity

Trimethylamine N-oxide (TMAO) is linked to cardiovascular disease (CVD) through partly altered central hemodynamics. We sought to examine if a low-calorie diet plus interval exercise (LCD+INT) intervention reduces TMAO more than a low-calorie diet (LCD) program alone in relation to hemodynamics, prior to clinically meaningful weight loss. Women with obesity were randomized to 2 weeks of LCD (n = 12, ~1200 kcal/d) or LCD+INT (n = 11; 60 min/d, 3 min at 90% and 50% HRpeak, respectively). A 180 min 75 g OGTT was performed to assess fasting TMAO and precursors (carnitine, choline, betaine, and trimethylamine (TMA)) as well as insulin sensitivity. Pulse wave analysis (applanation tonometry) including augmentation index (AIx75), pulse pressure amplification (PPA), forward (Pf) and backward pressure (Pb) waveforms, and reflection magnitude (RM) at 0, 60, 120, and 180 min was also analyzed. LCD and LCD+INT comparably reduced weight (p < 0.01), fasting glucose (p = 0.05), insulin tAUC180min (p < 0.01), choline (p < 0.01), and Pf (p = 0.04). Only LCD+INT increased VO2peak (p = 0.03). Despite no overall treatment effect, a high baseline TMAO was associated with decreased TMAO (r = -0.45, p = 0.03). Reduced TMAO was related to increased fasting PPA (r = -0.48, p = 0.03). Lowered TMA and carnitine correlated with higher fasting RM (r = -0.64 and r = -0.59, both p < 0.01) and reduced 120 min Pf (both, r = 0.68, p < 0.01). Overall, treatments did not lower TMAO. Yet, people with high TMAO pre-treatment reduced TMAO after LCD, with and without INT, in relation to aortic waveforms.

Intestinal Flora Metabolite Trimethylamine Oxide Is Inextricably Linked to Coronary Heart Disease

ABSTRACT

Atherosclerotic coronary heart disease is a common cardiovascular disease with high morbidity and mortality. In recent years, the incidence of coronary heart disease has gradually become younger, and biomarkers for predicting coronary heart disease have demonstrated valuable clinical prospects. Several studies have established an association between coronary heart disease and intestinal flora metabolites, including trimethylamine oxide (TMAO), which has attracted widespread attention from researchers. Investigations have also shown that plasma levels of TMAO and its precursors can predict cardiovascular risk in humans; however, TMAO's mechanism of action in causing coronary heart disease is not fully understood. This review examines TMAO's generation, the mechanism through which it causes coronary heart disease, and the approaches used to treat TMAO-caused coronary heart disease to possible avenues for future research on coronary heart disease and find new concepts for the treatment of the condition.

Bacterial Metabolites: A Link between Gut Microbiota and Dermatological Diseases

Dysbiosis has been identified in many dermatological conditions (e.g., psoriasis, atopic dermatitis, systemic lupus erythematosus). One of the ways by which the microbiota affect homeostasis is through microbiota-derived molecules (metabolites). There are three main groups of metabolites: short-chain fatty acids (SCFAs), tryptophan metabolites, and amine derivatives including trimethylamine N-oxide (TMAO). Each group has its own uptake and specific receptors through which these metabolites can exert their systemic function. This review provides up-to-date knowledge about the impact that these groups of gut microbiota metabolites may have in dermatological conditions. Special attention is paid to the effect of microbial metabolites on the immune system, including changes in the profile of the immune cells and cytokine disbalance, which are characteristic of several dermatological diseases, especially psoriasis and atopic dermatitis. Targeting the production of microbiota metabolites may serve as a novel therapeutic approach in several immune-mediated dermatological diseases.

Blood metabolomes as non-invasive biomarkers and targets of metabolic interventions for doxorubicin and trastuzumab-induced cardiotoxicity

This study aimed to identify the alterations of blood metabolome levels and their association with cardiac dysfunction and cardiac injury following treatment with doxorubicin and trastuzumab. Eight-week-old male Wistar rats were divided into four groups (n = 6 per group) to receive intraperitoneal injection with either: (1) 1 mL of normal saline solution (NSS) at days 0, 4, 8, 15, 22, and 29 (control group for doxorubicin); (2) 3 mg/kg/day of doxorubicin at days 0, 4, 8, 15, 22, and 29 (doxorubicin group); (3) 1 mL of NSS at days 0-6 (control group for trastuzumab); or (4) 4 mg/kg/day of trastuzumab at days 0-6 (trastuzumab group). Four days after the last injected dose, cardiac function was determined. The rats were then euthanized to collect venous blood and the heart for the quantification of 107 serum and 100 cardiac metabolomes using mass spectrometry-based targeted metabolomics. We observed strong relationships between 72 cardiac versus 61 serum metabolomes in doxorubicin and trastuzumab groups. Moreover, significant correlations between cardiac function and the cardiac injury biomarker versus 28 and 58 serum metabolomes were revealed in doxorubicin and trastuzumab-treated rats, respectively. Interestingly, the patterns of both serum and cardiac metabolome alterations differed between doxorubicin and trastuzumab groups. Our findings emphasize the potential role of the constituents of the blood metabolome as non-invasive biomarkers to assess severity and prognosis of heart failure induced by doxorubicin and trastuzumab. These findings may contribute to the development of metabolic-targeted therapy specific for cardioprotection during different phases of cancer treatment.

Gut Microbiota-Derived TMAO: A Causal Factor Promoting Atherosclerotic Cardiovascular Disease?

Trimethylamine-N-oxide (TMAO) is the main diet-induced metabolite produced by the gut microbiota, and it is mainly eliminated through renal excretion. TMAO has been correlated with an increased risk of atherosclerotic cardiovascular disease (ASCVD) and related complications, such as cardiovascular mortality or major adverse cardiovascular events (MACE). Meta-analyses have postulated that high circulating TMAO levels are associated with an increased risk of cardiovascular events and all-cause mortality, but the link between TMAO and CVD remains not fully consistent. The results of prospective studies vary depending on the target population and the outcome studied, and the adjustment for renal function tends to decrease or reverse the significant association between TMAO and the outcome studied, strongly suggesting that the association is substantially mediated by renal function. Importantly, one Mendelian randomization study did not find a significant association between genetically predicted higher TMAO levels and cardiometabolic disease, but another found a positive causal relationship between TMAO levels and systolic blood pressure, which-at least in part-could explain the link with renal function. The mechanisms by which TMAO can increase this risk are not clearly elucidated, but current evidence indicates that TMAO induces cholesterol metabolism alterations, inflammation, endothelial dysfunction, and platelet activation. Overall, there is no fully conclusive evidence that TMAO is a causal factor of ASCVD, and, especially, whether TMAO induces or just is a marker of hypertension and renal dysfunction requires further study.

A Heart-Healthy Diet for Cardiovascular Disease Prevention: Where Are We Now?

Purpose of Review

The relationship between cardiovascular health and diet is evolving. Lifestyle modifications including diet changes are the primary approach in managing cardiometabolic risk factors. Thus, understanding different diets and their impact on cardiovascular health is important in guiding primary and secondary prevention of cardiovascular disease (CVD). Yet, there are many barriers and limitations to adopting a heart healthy diet.

Recent Findings

Diets rich in fruits, vegetables, legumes, whole grains, and lean protein sources, with minimization/avoidance of processed foods, trans-fats, and sugar sweetened beverages, are recommended by prevention guidelines. The Mediterranean, DASH, and plant-based diets have all proven cardioprotective in varying degrees and are endorsed by professional healthcare societies, while other emerging diets such as the ketogenic diet and intermittent fasting require more long-term study. The effects of diet on the gut microbiome and on cardiovascular health have opened a new path for precision medicine to improve cardiometabolic risk factors. The effects of certain dietary metabolites, such as trimethylamine N-oxide, on cardiometabolic risk factors, along with the changes in the gut microbiome diversity and gene pathways in relation to CVD management, are being explored.

Summary

In this review, we provide a comprehensive up-to-date overview on established and emerging diets in cardiovascular health. We discuss the effectiveness of various diets and most importantly the approaches to nutritional counseling where traditional and non-traditional approaches are being practiced, helping patients adopt heart healthy diets. We address the limitations to adopting a heart healthy diet regarding food insecurity, poor access, and socioeconomic burden. Lastly, we discuss the need for a multidisciplinary team-based approach, including the role of a nutrition specialist, in implementing culturally-tailored dietary recommendations. Understanding the limitations and finding ways to overcome the barriers in implementing heart-healthy diets will take us miles in the path to CVD prevention and management.

Circulating Omega-3 and Omega-6 Fatty Acids, Cognitive Decline, and Dementia in Older Adults

BACKGROUND

Comprising nearly 35% of brain lipids, polyunsaturated fatty acids (PUFA) are essential for optimal brain function. However, the role of PUFA on cognitive health outcomes later in life is largely unknown.

OBJECTIVE

We investigated prospective associations of plasma phospholipid omega-3 (ALA [18 : 3], EPA [20 : 5], DPA [22 : 5], DHA [22 : 6]) and omega-6 (LA [18 : 2], AA [20 : 4]) PUFA with cognitive decline, risk of cognitive impairment and dementia among adults aged≥65 years in the Cardiovascular Health Study.

METHODS

Circulating fatty acid concentrations were measured serially at baseline (1992/1993), 6 years, and 13 years later. Cognitive decline and impairment were assessed using the 100-point Modified Mini-Mental State Examination (3MSE) up to 7 times. Clinical dementia was identified using adjudicated neuropsychological tests, and ICD-9 codes.

RESULTS

Among 3,564 older adults free of stroke and dementia at baseline, cognitive function declined annually by approximately -0.5 3MSE points; 507 participants developed cognitive impairment and 499 dementia over up to 23 years of follow-up. In multivariable models, higher circulating arachidonic acid (AA) concentrations were associated with slower cognitive decline and lower dementia risk, with associations growing stronger with greater length of follow-up (hazard ratio [HR,95% CI] of dementia per interquintile range, 0.74 [0.56-0.97] at 5 years, and 0.53 [0.37-0.77] at 15 years). Circulating docosapentaenoic (DPA) concentrations were associated with slower cognitive decline and lower risk of cognitive impairment (extreme-quintile HR, 0.72 [95% CI: 0.55, 0.95]). Findings were generally null or inconsistent for other omega-3 or omega-6 PUFA.

CONCLUSION

Circulating AA and DPA, but not other PUFA, are associated with slower rate of cognitive decline and lower risk of dementia or cognitive impairment later in life.

Circulating trimethylamine N-oxide levels do not predict 10-year survival in patients with or without coronary heart disease

BACKGROUND

Trimethylamine N-oxide (TMAO) is an amine oxide generated by gut microbial metabolism. TMAO may contribute to atherothrombosis and systemic inflammation. However, the prognostic value of circulating TMAO for risk stratification is uncertain.

METHODS

We assessed prospective relationships of plasma TMAO with long-term risk of all-cause, cardiovascular (CV), and non-CV mortality in the Western Norway Coronary Angiography Cohort (WECAC; 4132 patients with suspected coronary artery disease) and the Hordaland Health Study (HUSK; 6393 community-based subjects). Risk associations were examined using Cox regression analyses.

RESULTS

Mean follow-up was 9.8 and 10.5 years in WECAC and HUSK, respectively. Following adjustments for established CV risk factors and indices of renal function in WECAC, the hazard ratios (HRs) (95% confidence intervals [CIs]) per one standard deviation increase in log-transformed plasma TMAO were 1.04 (0.97-1.12), 1.06 (0.95-1.18), and 1.03 (0.93-1.13) for all-cause, CV, and non-CV mortality, respectively. Essentially similar results were obtained in patients with angiographically significant coronary artery disease and patients with reduced left ventricular ejection fraction. Corresponding HRs (95% CIs) in the HUSK cohort were 1.03 (0.96-1.10), 1.01 (0.89-1.13), and 1.03 (0.95-1.12) for all-cause-, CV, and non-CV mortality, respectively.

CONCLUSIONS

Circulating TMAO did not predict long-term all-cause, CV, or non-CV mortality in patients with coronary heart disease or in community-based adults. This large study does not support a role of TMAO for patient risk stratification in primary or secondary prevention.

Association between trimethylamine N-oxide and prognosis of patients with acute myocardial infarction and heart failure

AIMS

This study aimed to investigate the association between trimethylamine N-oxide (TMAO) and the prognosis and association between high-sensitivity C-reactive protein (hsCRP) and TMAO-associated cardiovascular risk in patients with acute myocardial infarction (AMI) complicated by heart failure (HF).

METHODS AND RESULTS

A total of 985 patients presenting with AMI and HF were consecutively enrolled at the Fuwai Hospital between March 2017 and January 2020. Patients were stratified into groups according to tertiles of TMAO levels and the median hsCRP levels. The primary endpoint was major adverse cardiac events (MACE), including all-cause death, recurrence of myocardial infarction, and rehospitalization due to HF. During a median follow-up of 716 days, 138 (14.0%) patients experienced MACE. Cox regression analyses showed that the adjusted hazard ratio (HR) for MACE was higher in patients in tertile 3 [TMAO > 9.52 μmol/L, HR: 1.85, 95% confidence interval (CI): 1.18-2.89; P = 0.007] than in tertile 1 (TMAO < 4.74 μmol/L), whereas no significant differences were detected between the patients in tertiles 1 and 2 (TMAO = 4.74-9.52 μmol/L, HR: 0.96, 95% CI: 0.59-1.58; P = 0.874). Restricted cubic spline regression depicted an S-shaped association between TMAO and MACE (P for nonlinearity = 0.012). In the setting of hsCRP above the median level (6.68 mg/L), per unit increase of TMAO was associated with a 20% increase of MACE risk (HR: 1.20, 95% CI: 1.05-1.37, P = 0.009); increasing tertiles of TMAO were significantly associated with a higher risk of MACE (adjusted P = 0.007 for interaction; P < 0.001 for trend across tertiles). The Kaplan-Meier analysis indicated that patients in tertile 3 had a significantly lower event-free survival (P = 0.001) when the hsCRP level was above the median level. No similar association between TMAO and MACE was observed when the hsCRP level was below the median level.

CONCLUSIONS

High plasma TMAO levels were independently correlated with poor prognosis in patients with AMI complicated by HF, especially in those with higher hsCRP levels. There was an S-shaped relationship between TMAO and HR for MACE.

Dietary Meat, Trimethylamine N-Oxide-Related Metabolites, and Incident Cardiovascular Disease Among Older Adults: The Cardiovascular Health Study

BACKGROUND

Effects of animal source foods (ASF) on atherosclerotic cardiovascular disease (ASCVD) and underlying mechanisms remain controversial. We investigated prospective associations of different ASF with incident ASCVD and potential mediation by gut microbiota-generated trimethylamine N-oxide, its L-carnitine-derived intermediates γ-butyrobetaine and crotonobetaine, and traditional ASCVD risk pathways.

METHODS

Among 3931 participants from a community-based US cohort aged 65+ years, ASF intakes and trimethylamine N-oxide-related metabolites were measured serially over time. Incident ASCVD (myocardial infarction, fatal coronary heart disease, stroke, other atherosclerotic death) was adjudicated over 12.5 years median follow-up. Cox proportional hazards models with time-varying exposures and covariates examined ASF-ASCVD associations; and additive hazard models, mediation proportions by different risk pathways.

RESULTS

After multivariable-adjustment, higher intakes of unprocessed red meat, total meat, and total ASF associated with higher ASCVD risk, with hazard ratios (95% CI) per interquintile range of 1.15 (1.01-1.30), 1.22 (1.07-1.39), and 1.18 (1.03-1.34), respectively. Trimethylamine N-oxide-related metabolites together significantly mediated these associations, with mediation proportions (95% CI) of 10.6% (1.0-114.5), 7.8% (1.0-32.7), and 9.2% (2.2-44.5), respectively. Processed meat intake associated with a nonsignificant trend toward higher ASCVD (1.11 [0.98-1.25]); intakes of fish, poultry, and eggs were not significantly associated. Among other risk pathways, blood glucose, insulin, and C-reactive protein, but not blood pressure or blood cholesterol, each significantly mediated the total meat-ASCVD association.

CONCLUSIONS

In this large, community-based cohort, higher meat intake associated with incident ASCVD, partly mediated by microbiota-derived metabolites of L-carnitine, abundant in red meat. These novel findings support biochemical links between dietary meat, gut microbiome pathways, and ASCVD.

Psoriasis: Interplay between dysbiosis and host immune system

With advancement in human microbiome research, an increasing number of scientific evidences have endorsed the key role of both gut and skin microbiota in the pathogenesis of psoriasis. Microbiome dysbiosis, characterized by altered diversity and composition, as well as rise of pathobionts, have been identified as possible triggers for recurrent episodes of psoriasis. Mechanistically, gut dysbiosis leads to "leaky gut syndrome" via disruption of epithelial bilayer, thereby, resulting in translocation of bacteria and other endotoxins to systemic circulation, which in turn, results in inflammatory response. Similarly, skin dysbiosis disrupts the cutaneous homeostasis, leading to invasion of bacteria and other pathogens to deeper layers of skin or even systemic circulation further enhanced by injury caused by pruritus-induced scratching, and elicit innate and adaptive inflammation. The present review explores the correlation of both skin and gut microbiota dysbiosis with psoriasis. Also, the studies highlighting the potential of bacteriotherapeutic approaches including probiotics, prebiotics, metabiotics, and fecal microbiota transplantation for the management of psoriasis have been discussed.

Gut Microbiota-Derived Metabolites and Cardiovascular Disease Risk: A Systematic Review of Prospective Cohort Studies

Gut microbiota-derived metabolites have recently attracted considerable attention due to their role in host-microbial crosstalk and their link with cardiovascular health. The MEDLINE-PubMed and Elsevier’s Scopus databases were searched up to June 2022 for studies evaluating the association of baseline circulating levels of trimethylamine N-oxide (TMAO), secondary bile acids, short-chain fatty acids (SCFAs), branched-chain amino acids (BCAAs), tryptophan and indole derivatives, with risk of cardiovascular disease (CVD). A total of twenty-one studies were included in the systematic review after evaluating 1210 non-duplicate records. There were nineteen of the twenty-one studies that were cohort studies and two studies had a nested case–control design. All of the included studies were of high quality according to the “Newcastle–Ottawa Scale”. TMAO was positively associated with adverse cardiovascular events and CVD/all-cause mortality in some, but not all of the included studies. Bile acids were associated with atrial fibrillation and CVD/all-cause mortality, but not with CVD. Positive associations were found between BCAAs and CVD, and between indole derivatives and major adverse cardiovascular events, while a negative association was reported between tryptophan and all-cause mortality. No studies examining the relationship between SCFAs and CVD risk were identified. Evidence from prospective studies included in the systematic review supports a role of microbial metabolites in CVD.

Targeting Trimethylamine N-Oxide: A New Therapeutic Strategy for Alleviating Atherosclerosis

Atherosclerosis (AS) is one of the most common cardiovascular diseases (CVDs), and there is currently no effective drug to reverse its pathogenesis. Trimethylamine N-oxide (TMAO) is a metabolite of the gut flora with the potential to act as a new risk factor for CVD. Many studies have shown that TMAO is involved in the occurrence and development of atherosclerotic diseases through various mechanisms; however, the targeted therapy for TMAO remains controversial. This article summarizes the vital progress made in relation to evaluations on TMAO and AS in recent years and highlights novel probable approaches for the prevention and treatment of AS.

Host-microbial interactions in metabolic diseases: from diet to immunity

Growing evidence suggests that the gut microbiome is an important contributor to metabolic diseases. Alterations in microbial communities are associated with changes in lipid metabolism, glucose homeostasis, intestinal barrier functions, and chronic inflammation, all of which can lead to metabolic disorders. Therefore, the gut microbiome may represent a novel therapeutic target for obesity, type 2 diabetes, and nonalcoholic fatty liver disease. This review discusses how gut microbes and their products affect metabolic diseases and outlines potential treatment approaches via manipulation of the gut microbiome. Increasing our understanding of the interactions between the gut microbiome and host metabolism may help restore the healthy symbiotic relationship between them.

Metabolomics of Arterial Stiffness

Arterial stiffness (AS) is one of the earliest detectable signs of structural and functional alterations of the vessel wall and an independent predictor of cardiovascular events and death. The emerging field of metabolomics can be utilized to detect a wide spectrum of intermediates and products of metabolism in body fluids that can be involved in the pathogenesis of AS. Research over the past decade has reinforced this idea by linking AS to circulating acylcarnitines, glycerophospholipids, sphingolipids, and amino acids, among other metabolite species. Some of these metabolites influence AS through traditional cardiovascular risk factors (e.g., high blood pressure, high blood cholesterol, diabetes, smoking), while others seem to act independently through both known and unknown pathophysiological mechanisms. We propose the term 'arteriometabolomics' to indicate the research that applies metabolomics methods to study AS. The 'arteriometabolomics' approach has the potential to allow more personalized cardiovascular risk stratification, disease monitoring, and treatment selection. One of its major goals is to uncover the causal metabolic pathways of AS. Such pathways could represent valuable treatment targets in vascular ageing.

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

BACKGROUND

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

TMAO and Gut Microbial-Derived Metabolites TML and γBB Are Not Associated with Thrombotic Risk in Patients with Venous Thromboembolism

Background: The present work evaluates the association between circulating concentrations of Trimethylamine-N-oxide (TMAO), gamma butyrobetaine (γBB), and trimetyllisine (TML) in controls and patients with venous thromboembolism (VTE) with coagulation parameters. Methods: The study involved 54 VTE patients and 57 controls. Platelet function, platelet hyperreactivity, platelet adhesiveness, thrombosis-associated parameters, and thrombin generation parameters were studied. Plasma TMAO, γBB, and TML determination was performed using an ultra-high-performance liquid chromatography system coupled with mass spectrometry. Results: No differences were found for TMAO, γBB, or TML concentrations between controls and VTE patients. In thrombin generation tests, TMAO, γBB, and TML showed a positive correlation with lag time and time to peak. TMAO, γBB, and TML negatively correlated with peak height. No significant differences were observed regarding TMAO, γBB, and TML concentrations between the two blood withdrawals, nor when the control and VTE patients were analyzed separately. No correlation was observed between these gut metabolites and platelet function parameters. Conclusions: No differences were found regarding TMAO, γBB, and TML concentrations between the control and VTE groups. Some correlations were found; however, they were mild or went in the opposite direction of what would be expected if TMAO and its derivatives were related to VTE risk.

Risk of Heart Failure in Patients With Nonalcoholic Fatty Liver Disease: JACC Review Topic of the Week

Heart failure (HF) and nonalcoholic fatty liver disease (NAFLD) are 2 conditions that have become important global public health problems. Emerging evidence supports a strong and independent association between NAFLD and the risk of new-onset HF, and there are multiple potential pathophysiological mechanisms by which NAFLD may increase risk of new-onset HF. The magnitude of this risk parallels the underlying severity of NAFLD, especially the level of liver fibrosis. Patients with NAFLD develop accelerated coronary atherosclerosis, myocardial alterations (mainly cardiac remodeling and hypertrophy), and certain arrhythmias (mainly atrial fibrillation), which may precede and promote the development of new-onset HF. This brief narrative review aims to provide an overview of the association between NAFLD and increased risk of new-onset HF, discuss the underlying mechanisms that link these 2 diseases, and summarize targeted pharmacological treatments for NAFLD that might also reduce the risk of HF.

Longitudinal Associations of Plasma TMAO and Related Metabolites with Cognitive Impairment and Dementia in Older Adults: The Cardiovascular Health Study

BACKGROUND

Animal studies suggest that gut microbiome metabolites such as trimethylamine N-oxide (TMAO) may influence cognitive function and dementia risk. However potential health effects of TMAO and related metabolites remain unclear.

OBJECTIVE

We examined prospective associations of TMAO, γ-butyrobetaine, crotonobetaine, carnitine, choline, and betaine with risk of cognitive impairment and dementia among older adults aged 65 years and older in the Cardiovascular Health Study (CHS).

METHODS

TMAO and metabolites were measured in stored plasma specimens collected at baseline. Incident cognitive impairment was assessed using the 100-point Modified Mini-Mental State Examination administered serially up to 7 times. Clinical dementia was identified using neuropsychological tests adjudicated by CHS Cognition Study investigators, and by ICD-9 codes from linked Medicare data. Associations of each metabolite with cognitive outcomes were assessed using Cox proportional hazards models.

RESULTS

Over a median of 13 years of follow-up, 529 cases of cognitive impairment, and 522 of dementia were identified. After multivariable adjustment for relevant risk factors, no associations were seen with TMAO, carnitine, choline, or betaine. In contrast, higher crotonobetaine was associated with 20-32% higher risk of cognitive impairment and dementia per interquintile range (IQR), while γ-butyrobetaine was associated with ∼25% lower risk of the same cognitive outcomes per IQR.∥Conclusion:These findings suggest that γ-butyrobetaine, crotonobetaine, two gut microbe and host metabolites, are associated with risk of cognitive impairment and dementia. Our results indicate a need for mechanistic studies evaluating potential effects of these metabolites, and their interconversion on brain health, especially later in life.

Related factors based on non-targeted metabolomics methods in minor ischaemic stroke

OBJECTIVE

This study aimed to identify potential biomarkers associated with the occurrence of minor ischaemic stroke.

METHODS

Four hundred patients hospitalized with minor ischaemic stroke were enrolled in the department of neurological internal medicine in Taiyuan Central Hospital, and 210 healthy subjects examined at the Taiyuan Central Hospital Medical Center during the same period were selected. We collected information on the general demographic characteristics and fasting blood samples of the subjects. We then used untargeted metabolomic assay to measure blood glucose, blood lipids, homocysteine, and high-sensitivity C-reactive protein.

RESULTS

There were statistically significant differences between the mild ischemic stroke group and the healthy control group in smoking, hypertension, and physical activity (P< 0.05). Compared with the healthy group, the minor ischaemic stroke group showed increased lactate, pyruvate, trimetlylamine oxide levels, and lactic acid, pyruvic acid, and trimethylamine N-oxidation (TMAO) levels were statistically significant (P< 0.001). In the minor ischaemic stroke risk model, hypertension, physical activity, smoking, and elevated TMAO levels influenced the occurrence of minor stroke.

CONCLUSION

Increased levels of lactic acid, pyruvate, and TMAO may be related to the pathophysiological changes in the minor ischaemic stroke population. High blood pressure, a lack of physical activity, smoking, and increased TMAO level were the influencing factors for the occurrence of minor ischaemic stroke. The serum metabolite TMAO may be associated with MS occurrence.