Choline Metabolism and Risk of Atrial Fibrillation and Heart Failure in the PREDIMED Study

Trimethylamine N-oxide: a meta-organismal axis linking the gut and fibrosis

BACKGROUND

Tissue fibrosis is a common pathway to failure in many organ systems and is the cellular and molecular driver of myriad chronic diseases that are incompletely understood and lack effective treatment. Recent studies suggest that gut microbe-dependent metabolites might be involved in the initiation and progression of fibrosis in multiple organ systems.

MAIN BODY OF THE MANUSCRIPT

In a meta-organismal pathway that begins in the gut, gut microbiota convert dietary precursors such as choline, phosphatidylcholine, and L-carnitine into trimethylamine (TMA), which is absorbed and subsequently converted to trimethylamine N-oxide (TMAO) via the host enzyme flavin-containing monooxygenase 3 (FMO3) in the liver. Chronic exposure to elevated TMAO appears to be associated with vascular injury and enhanced fibrosis propensity in diverse conditions, including chronic kidney disease, heart failure, metabolic dysfunction-associated steatotic liver disease, and systemic sclerosis.

CONCLUSION

Despite the high prevalence of fibrosis, little is known to date about the role of gut dysbiosis and of microbe-dependent metabolites in its pathogenesis. This review summarizes recent important advances in the understanding of the complex metabolism and functional role of TMAO in pathologic fibrosis and highlights unanswered questions.

Systematic Mendelian Randomization Exploring Druggable Genes for Hemorrhagic Strokes

Patients with hemorrhagic stroke have high rates of morbidity and mortality, and drugs for prevention are very limited. Mendelian randomization (MR) analysis can increase the success rate of drug development by providing genetic evidence. Previous MR analyses only analyzed the role of individual drug target genes in hemorrhagic stroke; therefore, we used MR analysis to systematically explore the druggable genes for hemorrhagic stroke. We sequentially performed summary-data-based MR analysis and two-sample MR analysis to assess the associations of all genes within the database with intracranial aneurysm, intracerebral hemorrhage, and their subtypes. Validated genes were further analyzed by colocalization. Only genes that were positive in all three analyses and were druggable were considered desirable genes. We also explored the mediators of genes affecting hemorrhagic stroke incidence. Finally, the associations of druggable genes with other cardiovascular diseases were analyzed to assess potential side effects. We identified 56 genes that significantly affected hemorrhagic stroke incidence. Moreover, TNFSF12, SLC22A4, SPARC, KL, RELT, and ADORA3 were found to be druggable. The inhibition of TNFSF12, SLC22A4, and SPARC can reduce the risk of intracranial aneurysm, subarachnoid hemorrhage, and intracerebral hemorrhage. Gene-induced hypertension may be a potential mechanism by which these genes cause hemorrhagic stroke. We also found that blocking these genes may cause side effects, such as ischemic stroke and its subtypes. Our study revealed that six druggable genes were associated with hemorrhagic stroke, and the inhibition of TNFSF12, SLC22A4, and SPARC had preventive effects against hemorrhagic strokes.

Cohort-based strategies as an in-house tool to evaluate and improve phenotyping robustness of LC-MS/MS lipidomics platforms

In recent years, instrumental improvements have enabled the spread of mass spectrometry-based lipidomics platforms in biomedical research. In mass spectrometry, the reliability of generated data varies for each compound, contingent on, among other factors, the availability of labeled internal standards. It is challenging to evaluate the data for lipids without specific labeled internal standards, especially when dozens to hundreds of lipids are measured simultaneously. Thus, evaluation of the performance of these platforms at the individual lipid level in interlaboratory studies is generally not feasible in a time-effective manner. Herein, using a focused subset of sphingolipids, we present an in-house validation methodology for individual lipid reliability assessment, tailored to the statistical analysis to be applied. Moreover, this approach enables the evaluation of various methodological aspects, including discerning coelutions sharing identical selected reaction monitoring transitions, pinpointing optimal labeled internal standards and their concentrations, and evaluating different extraction techniques. While the full validation according to analytical guidelines for all lipids included in a lipidomics method is currently not possible, this process shows areas to focus on for subsequent method development iterations as well as the robustness of data generated across diverse methodologies.

An inverse association of dietary choline with atherosclerotic cardiovascular disease among US adults: a cross-sectional NHANES analysis

BACKGROUND

The role of diet choline in atherosclerotic cardiovascular disease (ASCVD) is uncertain. Findings from animal experiments are contradictory while there is a lack of clinical investigations. This study aimed to investigate the association between choline intake and ASCVD based on individuals from the National Health and Nutrition Examination Survey (NHANES) database.

METHODS

This cross-sectional study was conducted in 5525 individuals from the NHANES between 2011 and 2018. Participants were categorized into the ASCVD (n = 5015) and non-ASCVD (n = 510) groups. Univariable and multivariable-adjusted regression analyses were employed to investigate the relationship between diet choline and pertinent covariates. Logistic regression analysis and restricted cubic spline analysis were used to evaluate the association between choline intake and ASCVD.

RESULTS

ASCVD participants had higher choline intake compared to those without ASCVD. In the higher tertiles of choline intake, there was a greater proportion of males, married individuals, highly educated individuals, and those with increased physical activity, but a lower proportion of smokers and drinkers. In the higher tertiles of choline intake, a lower proportion of individuals had a history of congestive heart failure and stroke. After adjusting for age, gender, race, ethnicity, and physical activity, an inverse association between choline intake and heart disease, stroke, and ASCVD was found. A restricted cubic spline analysis showed a mirrored J-shaped relationship between choline and ASCVD, stroke and congestive heart failure in males. There was no association between dietary choline and metabolic syndrome.

CONCLUSION

An inverse association was observed between choline intake and ASVCD among U.S. adults. Further large longitudinal studies are needed to test the causal relationship of choline and ASVCD.

Association between dietary macronutrient composition and plasma one-carbon metabolites and B-vitamin cofactors in patients with stable angina pectoris

Elevated plasma concentrations of several one-carbon metabolites are associated with increased CVD risk. Both diet-induced regulation and dietary content of one-carbon metabolites can influence circulating concentrations of these markers. We cross-sectionally analysed 1928 patients with suspected stable angina pectoris (geometric mean age 61), representing elevated CVD risk, to assess associations between dietary macronutrient composition (FFQ) and plasma one-carbon metabolites and related B-vitamin status markers (GC-MS/MS, LC-MS/MS or microbiological assay). Diet-metabolite associations were modelled on the continuous scale, adjusted for age, sex, BMI, smoking, alcohol and total energy intake. Average (geometric mean (95 % prediction interval)) intake was forty-nine (38, 63) energy percent (E%) from carbohydrate, thirty-one (22, 45) E% from fat and seventeen (12, 22) E% from protein. The strongest associations were seen for higher protein intake, i.e. with higher plasma pyridoxal 5'-phosphate (PLP) (% change (95 % CI) 3·1 (2·1, 4·1)), cobalamin (2·9 (2·1, 3·7)), riboflavin (2·4 (1·1, 3·7)) and folate (2·1 (1·2, 3·1)) and lower total homocysteine (tHcy) (-1·4 (-1·9, -0·9)) and methylmalonic acid (MMA) (-1·4 (-2·0, -0·8)). Substitution analyses replacing MUFA or PUFA with SFA demonstrated higher plasma concentrations of riboflavin (5·0 (0·9, 9·3) and 3·3 (1·1, 5·6)), tHcy (2·3 (0·7, 3·8) and 1·3 (0·5, 2·2)) and MMA (2·0 (0·2, 3·9) and 1·7 (0·7, 2·7)) and lower PLP (-2·5 (-5·3, 0·3) and -2·7 (-4·2, -1·2)). In conclusion, a higher protein intake and replacing saturated with MUFA and PUFA were associated with a more favourable metabolic phenotype regarding metabolites associated with CVD risk.

Choline induced cardiac dysfunction by inhibiting the production of endogenous hydrogen sulfide in spontaneously hypertensive rats

To investigate the exact effects of dietary choline on hypertensive heart disease (HHD) and explore the potential mechanisms, male spontaneously hypertensive rats (SHR) and Wistar Kyoto rats (WKY) were randomly divided into five groups as follows: WKY group, WKY + Choline group, SHR group, SHR + Choline group, and SHR + Choline + NaHS group. In choline treatment groups, rats were fed with 1.3% (w/v) choline in the drinking water for 3 months. The rats in the SHR + Choline + NaHS group were intraperitoneally injected with NaHS (100 micromol/kg/day, a hydrogen sulfide (H2S) donor) for 3 months. After 3 months, left ventricular ejection fraction (LVEF) and fractional shortening (LVFS), the indicators of cardiac function measured by echocardiography, were increased significantly in SHR as compared to WKY, although there was no significant difference in collagen volumes and Bax/Bcl-2 ratio between the two groups, indicating the early stage of cardiac hypertrophy. There was a significant decrease in LVEF and LVFS and an increase in collagen volumes and Bax/Bcl-2 ratio in SHR fed with choline, meanwhile, plasma H2S levels were significantly decreased significantly in SHR fed with choline accompanying by the decrease of cystathionine-gamma-lyase (CSE) activity. Three months of NaHS significantly increased plasma H2S levels, ameliorated cardiac dysfunction and inhibited cardiac fibrosis and apoptosis in SHR fed with choline. In conclusion, choline aggravated cardiac dysfunction in HHD through inhibiting the production of endogenous H2S, which was reversed by supplementation of exogenous H2S donor.

Gut-Lung Axis in Focus: Deciphering the Impact of Gut Microbiota on Pulmonary Arterial Hypertension

Recent advancements in the understanding of pulmonary arterial hypertension (PAH) have highlighted the significant role of the gut microbiota (GM) in its pathogenesis. This comprehensive review delves into the intricate relationship between the GM and PAH, emphasizing the influence of gut microbial composition and the critical metabolites produced. We particularly focus on the dynamic interaction between the gut and lung, examining how microbial dysbiosis contributes to PAH development through inflammation, altered immune responses, and changes in the gut-lung axis. Noteworthy findings include variations in the ratios of key bacterial groups such as Firmicutes and Bacteroidetes in PAH and the pivotal roles of metabolites like trimethylamine N-oxide (TMAO), short-chain fatty acids (SCFAs), and serotonin in the disease's progression. Additionally, the review elucidates potential diagnostic biomarkers and novel therapeutic approaches, including the use of probiotics and fecal microbiota transplantation, which leverage the gut microbiota for managing PAH. This review encapsulates the current state of research in this field, offering insights into the potential of gut microbiota modulation as a promising strategy in PAH diagnosing and treatment.

The correlation between gut microbiome and atrial fibrillation: pathophysiology and therapeutic perspectives

Regulation of gut microbiota and its impact on human health is the theme of intensive research. The incidence and prevalence of atrial fibrillation (AF) are continuously escalating as the global population ages and chronic disease survival rates increase; however, the mechanisms are not entirely clarified. It is gaining awareness that alterations in the assembly, structure, and dynamics of gut microbiota are intimately engaged in the AF progression. Owing to advancements in next-generation sequencing technologies and computational strategies, researchers can explore novel linkages with the genomes, transcriptomes, proteomes, and metabolomes through parallel meta-omics approaches, rendering a panoramic view of the culture-independent microbial investigation. In this review, we summarized the evidence for a bidirectional correlation between AF and the gut microbiome. Furthermore, we proposed the concept of "gut-immune-heart" axis and addressed the direct and indirect causal roots between the gut microbiome and AF. The intricate relationship was unveiled to generate innovative microbiota-based preventive and therapeutic interventions, which shed light on a definite direction for future experiments.

Alterations of the gut microbiome and metabolic profile in CVB3-induced mice acute viral myocarditis

BACKGROUND

Acute viral myocarditis (AVMC) is an inflammatory disease of the myocardium. Evidence indicates that dysbiosis of gut microbiome and related metabolites intimately associated with cardiovascular diseases through the gut-heart axis.

METHODS

We built mouse models of AVMC, then applied 16 S rDNA gene sequencing and UPLC-MS/MS metabolomics to explore variations of gut microbiome and disturbances of cardiac metabolic profiles.

RESULTS

Compared with Control group, analysis of gut microbiota showed lower diversity in AVMC, decreased relative abundance of genera mainly belonging to the phyla Bacteroidetes, and increased of phyla Proteobacteria. Metabolomics analysis showed disturbances of cardiac metabolomics, including 62 increased and 84 decreased metabolites, and mainly assigned to lipid, amino acid, carbohydrate and nucleotide metabolism. The steroid hormone biosynthesis, cortisol synthesis and secretion pathway were particularly enriched in AVMC. Among them, such as estrone 3-sulfate, desoxycortone positively correlated with disturbed gut microbiome.

CONCLUSION

In summary, both the structure of the gut microbiome community and the cardiac metabolome were significantly changed in AVMC. Our findings suggest that gut microbiome may participate in the development of AVMC, the mechanism may be related to its role in dysregulated metabolites such as steroid hormone biosynthesis.

Associations of serum betaine with blood pressure and hypertension incidence in middle-aged and older adults: a prospective cohort study

The impact of betaine on the development of hypertension remains unclear, and prospective data are sparse. We aimed to investigate the association of serum betaine with repeated measurements of blood pressure (BP) and hypertension incidence. This study was based on the Guangzhou Nutrition and Health Study (GNHS), a community-based prospective cohort study in China. Baseline serum betaine was measured by high-performance liquid chromatography-tandem mass spectrometry. BP and hypertension status were assessed at the baseline and 3-year intervals. Linear mixed-effects models (LMEMs) were used to analyze the longitudinal association of serum betaine with BP (n = 1996). Cox proportional hazard models were used to evaluate the association of baseline serum betaine with hypertension incidence (n = 1339). LMEMs showed that compared with the lowest quartile group, the higher quartile groups had lower systolic blood pressure (SBP), diastolic blood pressure (DBP) and pulse pressure (all P-trend < 0.05). Each standard deviation (16.3 μmol L^-1) increase in serum betaine was associated with -0.92 (-1.52, -0.32) mmHg of SBP, -0.49 (-0.84, -0.13) mmHg of DBP and -0.43 (-0.81, -0.05) mmHg of pulse pressure. During a median follow-up of 9.2 years, 371 incident cases of hypertension were identified. Serum betaine was associated with lower risk of hypertension only when comparing the third quartile level with the lowest quartile (HR, 0.74; 95% CI, 0.56-0.99). A nonlinear association between serum betaine and the risk of hypertension was found (P-nonlinear = 0.040). A higher serum betaine level was associated with lower risk of hypertension below 54.5 μmol L^-1. Our findings suggested that higher serum betaine was associated with favorable blood pressure in middle-aged and older Chinese adults. Higher concentrations of serum betaine were related to lower hypertension risk in people with relatively low serum betaine concentrations.

Gut Microbiota and Atrial Fibrillation: Pathogenesis, Mechanisms and Therapies

Over the past decade there has been an interest in understanding the role of gut microbiota in the pathogenesis of AF. A number of studies have linked the gut microbiota to the occurrence of traditional AF risk factors such as hypertension and obesity. However, it remains unclear whether gut dysbiosis has a direct effect on arrhythmogenesis in AF. This article describes the current understanding of the effect of gut dysbiosis and associated metabolites on AF. In addition, current therapeutic strategies and future directions are discussed.

Association of gut microbiome dysbiosis with the progression of atrial fibrillation: A systematic review

OBJECTIVE

Many clinical and preclinical studies have implicated an association between atrial fibrillation (AF) and its progression to imbalances in the gut microbiome composition. The gut microbiome is a diverse and complex ecosystem containing billions of microorganisms that produce biologically active metabolites influencing the host disease development.

METHODS

For this review, a literature search was conducted using digital databases to systematically identify the studies reporting the association of gut microbiota with AF progression.

RESULTS

In a total of 14 studies, 2479 patients were recruited for the final analysis. More than half (n = 8) of the studies reported alterations in alpha diversity in atrial fibrillation. As for the beta diversity, 10 studies showed significant alterations. Almost all studies that assessed gut microbiota alterations reported major taxa associated with atrial fibrillation. Most studies focused on short-chain fatty acids (SCFAs), whereas three studies evaluated TMAO levels in the blood, which is the breakdown product of dietary l-carnitine, choline, and lecithin. Moreover, an independent cohort study assessed the relationship between phenylacetylglutamine (PAGIn) and AF.

CONCLUSION

Intestinal dysbiosis is a modifiable risk factor that might provide newer treatment strategies for AF prevention. Well-designed research and prospective randomized interventional studies are required to target the gut dysbiotic mechanisms and determine the gut dysbiotic-AF relationship.

Gut Molecules in Cardiometabolic Diseases: The Mechanisms behind the Story

Atherosclerotic cardiovascular disease is the most common cause of morbidity and mortality worldwide. Diabetes mellitus increases cardiovascular risk. Heart failure and atrial fibrillation are associated comorbidities that share the main cardiovascular risk factors. The use of incretin-based therapies promoted the idea that activation of alternative signaling pathways is effective in reducing the risk of atherosclerosis and heart failure. Gut-derived molecules, gut hormones, and gut microbiota metabolites showed both positive and detrimental effects in cardiometabolic disorders. Although inflammation plays a key role in cardiometabolic disorders, additional intracellular signaling pathways are involved and could explain the observed effects. Revealing the involved molecular mechanisms could provide novel therapeutic strategies and a better understanding of the relationship between the gut, metabolic syndrome, and cardiovascular diseases.

Intestinal Barrier Dysfunction and Microbial Translocation in Patients with First-Diagnosed Atrial Fibrillation

BACKGROUND

According to the leaky gut concept, microbial products (e.g., lipopolysaccharide, LPS) enter the circulation and mediate pro-inflammatory immunological responses. Higher plasma LPS levels have been reported in patients with various cardiovascular diseases, but not specifically during early atrial fibrillation (AF).

METHODS

We studied data and blood samples from patients presenting with first-diagnosed AF (FDAF) (n = 80) and 20 controls.

RESULTS

Circulating biomarkers that are suggestive of mucosal inflammation (zonulin, mucosal adhesion molecule MAdCAM-1) and intestinal epithelium damage (intestinal fatty acid binding protein, IFABP) were increased in the plasma of patients with FDAF when compared to patients with chronic cardiovascular diseases but without AF. Surrogate plasma markers of increased intestinal permeability (LPS, CD14, LPS-binding protein, gut-derived LPS-neutralising IgA antibodies, EndoCAbs) were detected during early AF. A reduced ratio of IgG/IgM EndoCAbs titres indicated chronic endotoxaemia. Collagen turnover biomarkers, which corresponded to the LPS values, suggested an association of gut-derived low-grade endotoxaemia with adverse structural remodelling. The LPS concentrations were higher in FDAF patients who experienced a major adverse cardiovascular event.

CONCLUSIONS

Intestinal barrier dysfunction and microbial translocation accompany FDAF. Improving gut permeability and low-grade endotoxaemia might be a potential therapeutic approach to reducing the disease progression and cardiovascular complications in FDAF.

Epidemiology and modifiable risk factors for atrial fibrillation

The global prevalence of atrial fibrillation (AF) has increased substantially over the past three decades and is currently approximately 60 million cases. Incident AF and its clinical consequences are largely the result of risk factors that can be modified by lifestyle changes. In this Review, we provide evidence that the lifetime risk of AF is modified not only by sex and race but also through the clinical risk factor and comorbidity burden of individual patients. We begin by summarizing the epidemiology of AF, focusing on non-modifiable and modifiable risk factors, as well as targets and strategies for the primary prevention of AF. Furthermore, we evaluate the role of modifiable risk factors in the secondary prevention of AF as well as the potential effects of risk factor interventions on the frequency and severity of subsequent AF episodes. We end the Review by proposing strategies that require evaluation as well as global policy changes that are needed for the prevention of incident AF and the management of recurrent episodes in patients already affected by AF.

Dietary precursors and cardiovascular disease: A Mendelian randomization study

Background

The Dietary precursor has been identified as a contributor in the development of cardiovascular disease. However, it is inconsistent if dietary precursors could affect the process of cardiovascular disease.

Methods

Here we performed Mendelian randomization (MR) analysis of the data from genome-wide association study of European ancestry to evaluate the independent effects of three dietary precursors on cardiovascular disease (CVD), myocardial infarction (MI), heart failure (HF), atrial fibrillation (AF), and valvular disease (VHD). Inverse variance weighting method was used for the MR estimation. Sensitivity was determined by MR-PRESSO analysis, weighted median analysis, MR-Egger analysis, and Leave-one-out analysis.

Results

We found that elevated choline level had a causal relationship with VHD [odds ratio (OR) = 1.087, 95% confidence interval (CI), 1.003-1.178, P = 0.041] and MI (OR = 1.250, 95% CI, 1.041-1.501, P = 0.017) by single-variable MR analysis. Furthermore, elevated carnitine level was associated with MI (OR = 5.007, 95% CI, 1.693-14.808, P = 0.004) and HF (OR = 2.176, 95% CI, 1.252-3.780, P = 0.006) risk. In addition, elevated phosphatidylcholine level can increase the risk of MI (OR = 1.197, 95% CI, 1.026-1.397, P = 0.022).

Conclusion

Our data show that choline increases VHD or MI risk, carnitine increases the risk of MI or HF, and phosphatidylcholine increases HF risk. These findings suggest the possibility that decrease in choline level in circulation may be able to reduce overall VHD or MI risk, reduce in carnitine level could be decrease MI and HF risks as well as decrease in phosphatidylcholine could reduce MI risk.

The role of the gut microbiota in health and cardiovascular diseases

The gut microbiota is critical to human health, such as digesting nutrients, forming the intestinal epithelial barrier, regulating immune function, producing vitamins and hormones, and producing metabolites to interact with the host. Meanwhile, increasing evidence indicates that the gut microbiota has a strong correlation with the occurrence, progression and treatment of cardiovascular diseases (CVDs). In patients with CVDs and corresponding risk factors, the composition and ratio of gut microbiota have significant differences compared with their healthy counterparts. Therefore, gut microbiota dysbiosis, gut microbiota-generated metabolites, and the related signaling pathway may serve as explanations for some of the mechanisms about the occurrence and development of CVDs. Several studies have also demonstrated that many traditional and latest therapeutic treatments of CVDs are associated with the gut microbiota and its generated metabolites and related signaling pathways. Given that information, we summarized the latest advances in the current research regarding the effect of gut microbiota on health, the main cardiovascular risk factors, and CVDs, highlighted the roles and mechanisms of several metabolites, and introduced corresponding promising treatments for CVDs regarding the gut microbiota. Therefore, this review mainly focuses on exploring the role of gut microbiota related metabolites and their therapeutic potential in CVDs, which may eventually provide better solutions in the development of therapeutic treatment as well as the prevention of CVDs.

Plasma trimethylamine-N-oxide, its precursors and risk of cardiovascular events in patients with acute coronary syndrome: Mediating effects of renal function

Aims

To examine associations of the gut microbial metabolite trimethylamine-N-oxide (TMAO) and its precursors with risk of cardiovascular events in acute coronary syndrome (ACS), and determine whether these associations were mediated by renal function.

Methods

In this prospective cohort study, we included 309 patients with ACS. During a mean follow-up of 6.7 years, 131 patients developed major adverse cardiovascular events (MACE) (myocardial infarction, hospitalization for heart failure, and all-cause mortality). Plasma concentrations of TMAO, trimethylamine (TMA), choline, betaine, dimethylglycine and L-carnitine were profiled by liquid chromatography tandem mass spectrometry. Hazard ratios were estimated with multivariable Cox regression models. The mediating role of estimated glomerular filtration rate (eGFR) was tested under a counterfactual framework.

Results

After adjustment for traditional cardiovascular risk factors and medications, participants in the highest tertile vs. the lowest tertile of baseline TMAO and dimethylglycine concentrations had a higher risk of MACE [(HR: 1.83; 95% CI: 1.08, 3.09) and (HR: 2.26; 95% CI: 1.17, 3.99), respectively]. However, with regards to TMAO these associations were no longer significant, whereas for dimethylglycine, the associations were attenuated after additional adjustment for eGFR. eGFR mediated the associations of TMAO (58%) and dimethylglycine (32%) with MACE incidence. The associations between dimethylglycine and incident MACE were confirmed in an internal validation. No significant associations were found for TMA, choline, betaine and L-carnitine.

Conclusion

These findings suggest that renal function may be a key mediator in the association of plasma TMAO with the development of cardiovascular events after ACS. The present findings also support a role of dimethylglycine in the pathogenesis of MACE, which may be mediated, at least partially, by renal function.

Microbial metabolites and heart failure: Friends or enemies?

Heart failure (HF), a global health issue characterized by structural or functional cardiac dysfunction, which was found to be associated with the gut microbiome recently. Although multiple studies suggested that the gut microbiome may have an impact on the development of cardiovascular diseases, the underlying mechanism of the gut microbiome in HF remains unclear. The study of metabolites from gut microbiota influenced by dietary nutrition uptake suggested that gut microbiota may affect the process of HF. However, on the basis of the microbiota’s complicated roles and their interactions with metabolites, studies of microbial metabolites in HF had rarely been described so far. In this review, we focused on dietary nutrition-related factors that were involved in the development and progression of HF, such as trimethylamine N-oxide (TMAO), short-chain fatty acids (SCFAs), and bile acids (BAs), to summarize their advances and several potential targets in HF. From a therapeutic standpoint, we discussed microbial metabolites as a potential strategy and their applications in HF as well.

Vegan nutrition: a preliminary guide for health professionals

Since the beginning of the 21st century, interest in vegan diets has been rapidly increasing in most countries. Misconceptions about vegan diets are widespread among the general population and health professionals. Vegan diets can be health-promoting and may offer certain important advantages compared to typical Western (and other mainstream) eating patterns. However, adequate dietary sources/supplements of nutrients of focus specific to vegan diets should be identified and communicated. Without supplements/fortified foods, severe vitamin B12 deficiency may occur. Other potential nutrients of focus are calcium, vitamin D, iodine, omega-3 fatty acids, iron, zinc, selenium, vitamin A, and protein. Ensuring adequate nutrient status is particularly important during pregnancy, lactation, infancy, and childhood. Health professionals are often expected to be able to provide advice on the topic of vegan nutrition, but a precise and practical vegan nutrition guide for health professionals is lacking. Consequently, it is important and urgent to provide such a set of dietary recommendations. It is the aim of this article to provide vegan nutrition guidelines, based on current evidence, which can easily be communicated to vegan patients/clients, with the goal of ensuring adequate nutrient status in vegans.

Commercial Extruded Plant-Based Diet Lowers Circulating Levels of Trimethylamine N-Oxide (TMAO) Precursors in Healthy Dogs: A Pilot Study

Elevations in circulating trimethylamine N-oxide (TMAO) and its precursors are observed in humans and dogs with heart failure and are associated with adverse outcomes in people. Dietary intervention that reduces or excludes animal ingredients results in rapid reduction of plasma TMAO and TMAO precursors in people, but the impact of diet in dogs has not been studied. The objective of the current study was to determine the effect of diet on plasma TMAO and 2 of its precursors (choline and betaine) in dogs fed a commercial extruded plant-based diet (PBD) or a commercial extruded traditional diet (TD) containing animal and plant ingredients. Sixteen healthy adult mixed breed dogs from a university colony were enrolled in a randomized, 2-treatment, 2-period crossover weight-maintenance study. Mean (SD) age and body weight of the dogs were 2.9 years (± 1.7) and 14.5 kg (± 4.0), respectively. Eight dogs were female (3 intact, 5 spayed) and 8 dogs were male (4 intact, 4 castrated). Plasma choline, betaine and TMAO were quantified by LC-SID-MRM/MS at baseline, and after 4 weeks on each diet. Choline and betaine were also quantified in the diets. Plasma choline levels were significantly lower (P = 0.002) in dogs consuming a PBD (Mean ± SD, 6.8 μM ± 1.2 μM) compared to a TD (Mean ± SD, 7.8 μM ± 1.6 μM). Plasma betaine levels were also significantly lower (P = 0.03) in dogs consuming a PBD (Mean ± SD, 109.1 μM ± 25.3 μM) compared to a TD (Mean ± SD, 132.4 μM ± 32.5 μM). No difference (P = 0.71) in plasma TMAO was detected in dogs consuming a PBD (Median, IQR, 2.4 μM, 2.1 μM) compared to a TD (Median, IQR, 2.3 μM, 1.1 μM). Betaine content was lower in the PBD than in the TD while choline content was similar in the diets. Our findings indicate consumption of a commercial extruded PBD for 4 weeks reduces circulating levels of the TMAO precursors choline and betaine, but not TMAO, in healthy adult dogs.

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.

The heart and gut relationship: a systematic review of the evaluation of the microbiome and trimethylamine-N-oxide (TMAO) in heart failure

There is an expanding body of research on the bidirectional relationship of the human gut microbiome and cardiovascular disease, including heart failure (HF). Researchers are examining the microbiome and gut metabolites, primarily trimethylamine-N-oxide (TMAO), to understand clinically observed outcomes. This systematic review explored the current state of the science on the evaluation and testing of the gut biome in persons with HF. Using electronic search methods of Medline, Embase, CINAHL, and Web of Science, until December 2021, we identified 511 HF biome investigations between 2014 and 2021. Of the 30 studies included in the review, six were 16S rRNA and nineteen TMAO, and three both TMAO and 16S rRNA, and two bacterial cultures. A limited range of study designs were represented, the majority involving single cohorts (n = 10) and comparing individuals with HF to controls (n = 15). Patients with HF had less biodiversity in fecal samples compared to controls. TMAO is associated with age, BNP, eGFR, HF severity, and poor outcomes including hospitalizations and mortality. Inconsistent across studies was the ability of TMAO to predict HF development, the independent prognostic value of TMAO when controlling for renal indices, and the relationship of TMAO to LVEF and CRP. Gut microbiome dysbiosis is associated with HF diagnosis, disease severity, and prognostication related to hospitalizations and mortality. Gut microbiome research in patients with HF is developing. Further longitudinal and multi-centered studies are required to inform interventions to promote clinical decision-making and improved patient outcomes.

The Emerging Role of the Gut Microbiome in Cardiovascular Disease: Current Knowledge and Perspectives

The collection of normally non-pathogenic microorganisms that mainly inhabit our gut lumen shapes our health in many ways. Structural and functional perturbations in the gut microbial pool, known as “dysbiosis”, have been proven to play a vital role in the pathophysiology of several diseases, including cardiovascular disease (CVD). Although therapeutic regimes are available to treat this group of diseases, they have long been the main cause of mortality and morbidity worldwide. While age, sex, genetics, diet, tobacco use, and alcohol consumption are major contributors (World Health Organization, 2018), they cannot explain all of the consequences of CVD. In addition to the abovementioned traditional risk factors, the constant search for novel preventative and curative tools has shed light on the involvement of gut bacteria and their metabolites in the pathogenesis of CVD. In this narrative review, we will discuss the established interconnections between the gut microbiota and CVD, as well as the plausible therapeutic perspectives.

Gut Microbiota and Metabolites in Atrial Fibrillation Patients and Their Changes after Catheter Ablation

The gut microbiota has been shown to be associated with multiple cardiovascular diseases, but there is little research on the gut microbiota and atrial fibrillation (AF); thus, how the gut microbiota and metabolites change in AF patients after catheter ablation is unclear. In this study, we used 16S rRNA high-throughput sequencing and nontargeted metabolomic detection to conduct horizontal and longitudinal analyses of the gut microbiota and metabolites of AF patients. Compared with a control group, species richness and diversity increased significantly in AF patients. Among them, opportunistic pathogenic bacteria, such as Klebsiella, Haemophilus, Streptococcus, and Enterococcus, were significantly increased, and symbiotic bacteria, such as Agathobacter and Butyrivibrio, were significantly reduced. After catheter ablation, intestinal symbiotic bacteria (Lactobacillus, Agathobacter, Lachnospira, etc.) were increased in most AF patients, while pathogenic bacteria (Ruminococcus, etc.) were reduced. Moreover, in AF patients, caffeine, which was negatively correlated with Klebsiella, was downregulated, and estradiol and ascorbic acid, which were positively correlated with Agathobacter, were also downregulated. After catheter ablation, citrulline, which was positively correlated with Ralstonia and Lactobacillus, was increased. Oleanolic acid, which was negatively correlated with Ralstonia was downregulated. In conclusion, our results not only show overall changes in the gut microbiota and metabolites in AF patients but also indicate their changes in the short term after catheter ablation. These data will provide novel possibilities for the future clinical diagnosis and treatment of AF.

IMPORTANCE Gut microbiota and metabolites play a very important role in human health and can not only assess human health but also treat and prevent diseases. We analyzed the characteristics of the microbiota and metabolites in the human gut and found the effect of disease on gut microbiota and metabolites, which may be of important value in the pathogenesis of atrial fibrillation. At the same time, we also observed dynamic changes in gut microbiota and metabolites with the intervention of catheter ablation, which was not available in previous studies.

Metabolites and novel compounds with anti-microbial or antiaging activities from Cordyceps fumosorosea

High-resolution mass spectrometry (HRMS) and nuclear magnetic resonance (NMR) analysis revealed that there are 20 main components in spores and mycelia extract of Cordyceps fumosorosea strain RCEF 6672 including mannitol (1), uridine (2), adenine (3). N⁶-(2-hydroxyethyl)-adenosine (4). N⁶-(2-hydroxyethylacetate)-adenosine (5), fumosoroseanoside A (6) and B (7), ovalicin-4α-alcohol (8), 1-linoleoyl-sn-glycero-3-phosphocholine (9) and its isomer (10), fumosoroseain A (11) and its isomer (12), 5 non-ribosomal peptides (13 to 17) and 3 fatty acids (18 to 20). The compounds 5, 6, 7, 9 and 11 were prepared with preparative and semi-preparative HPLC and identified with 1D and 2D NMR. Compounds 4 and 5 were the first time identified from C. fumosorosea. Compounds 6, 7 and 11 are novel compounds. Compounds 6 and 7 showed antibacterial and antifungal activities, and 11 showed antiaging activity. All the secondary metabolites (4 to 8 and 11 to 17) have strong bioactivities indicating that the metabolites have pharmaceutical development potentiality.

Clarified small molecular metabolites of C. fumosorosea for the first time.

Identified three novel compounds with antimicrobial or antiaging activities.

The fungus has development potentiality for rich in bioactive metabolites.

Effects of Gut Microbiota and Metabolites on Heart Failure and Its Risk Factors: A Two-Sample Mendelian Randomization Study

Introduction

Previous observational studies have indicated that gut microbiota and metabolites may contribute to heart failure and its risk factors. However, with the limitation of reverse causality and confounder in observational studies, such relationship remains unclear. This study aims to reveal the causal effect of gut microbiota and metabolites on heart failure and its risk factors.

Methods

This study collected summary statistics regarding gut microbiota and metabolites, heart failure, diabetes, hypertension, chronic kidney disease, myocardial infarction, atrial fibrillation, hypertrophic cardiomyopathy, dilated cardiomyopathy, coronary heart disease, valvular heart disease, and myocarditis. Two-sample Mendelian randomization analysis was performed using MR-Egger, inverse variance weighted (IVW), MR-PRESSO, maximum likelihood, and weighted median.

Results

Results from gene prediction showed that among all gut microbiota, candida, shigella, and campylobacter were not associated with higher incidence of heart failure. However, genetic prediction suggested that for every 1 unit increase in shigella concentration, the relative risk increased by 38.1% for myocarditis and 13.3% for hypertrophic cardiomyopathy. Besides, for every 1 unit increased in candida concentration, the relative risk of chronic kidney disease increased by 7.1%. As for intestinal metabolites, genetic prediction results suggested that for every 1 unit increase in betaine, the relative risk of heart failure and myocardial infarction increased by 1.4% and 1.7%, separately.

Conclusions

This study suggested new evidence of the relationship between gut microbiota and heart failure and its risk factors, which may shed light on designing microbiome- and microbiome-dependent metabolite interventions on heart failure and its risk factors in clinical trials in the future.

Higher circulating Trimethylamine N-oxide levels are associated with worse severity and prognosis in pulmonary hypertension: a cohort study

BACKGROUND

Trimethylamine N-oxide (TMAO), the gut microbiota-dependent metabolite, is a potential biomarker in several cardiovascular diseases. However, no study has investigated its value in pulmonary hypertension (PH). Therefore, this study aimed to explore the association between plasma TMAO levels and prognosis in patients with PH.

METHODS

Inpatients with idiopathic/heritable pulmonary arterial hypertension (IPAH/HPAH), PAH associated with congenital heart disease (CHD-PAH), and chronic thromboembolic pulmonary hypertension (CTEPH) at Fuwai Hospital were enrolled after excluding those with relative comorbidities. The endpoint was defined as a composite outcome including death, rehospitalisation due to heart failure, and at least 15% decreased 6-min walk distance from the baseline. Fasting blood samples were collected to measure plasma levels of TMAO and other clinical indicators. The associations between TMAO levels with disease severity and patients' prognosis were investigated.

RESULTS

In total, 163 patients with PH were included, with a mean follow-up duration of 1.3 years. After adjusting for confounding factors, elevated TMAO levels were still associated with severe disease conditions. TMAO levels dynamically decreased in stable and improved patients after treatment [ΔTMAO = - 0.2 (- 1.6, 0.7) μmol/L, P = 0.006]. Moreover, high plasma TMAO levels predicted a poor prognosis in the PH cohort (P < 0.001), and the association remained significant after adjusting the confounders, including treatment, risk stratification, and PH subtypes.

CONCLUSION

Elevated plasma TMAO levels were associated with severe disease conditions and poor prognosis in patients with PH, indicating its potential biomarker role in PH.

Quantification of choline in serum and plasma using a clinical nuclear magnetic resonance analyzer

BACKGROUND

Choline, a gut microbiome metabolite, is associated with cardiovascular risk and other chronic illnesses. The aim was to develop a high-throughput nuclear magnetic resonance (NMR)-based assay to measure choline on the Vantera® Clinical Analyzer.

METHODS

A non-negative deconvolution algorithm was developed to quantify choline. Assay performance was evaluated using CLSI guidelines.

RESULTS

Deming regression analysis comparing choline concentrations by NMR and mass spectrometry (n = 28) exhibited a correlation coefficient of 0.998 (intercept = -9.216, slope = 1.057). The LOQ were determined to be 7.1 µmol/L in serum and 5.9 µmol/L in plasma. The coefficients of variation (%CV) for intra- and inter-assay precision ranged from 6.2 to 14.8% (serum) and 5.4-11.3% (plasma). Choline concentrations were lower in EDTA plasma by as much as 38% compared to serum, however, choline was less stable in serum compared to plasma. In a population of apparently healthy adults, the reference interval was <7.1-20.0 µmol/L (serum) and <5.9-13.1 µmol/L (plasma). Linearity was demonstrated well beyond these intervals. No interference was observed for a number of substances tested.

CONCLUSIONS

The newly developed, high-throughput NMR-based assay exhibited good performance characteristics enabling quantification of choline in serum and plasma for clinical use.

Gut Metabolite Trimethylamine-N-Oxide in Atherosclerosis: From Mechanism to Therapy

Atherosclerosis is associated with various pathological manifestations, such as ischemic heart disease, ischemic stroke, and peripheral arterial disease, and remains a leading cause of public health concern. Atherosclerosis is an inflammatory disease characterized by endothelial dysfunction; vascular inflammation; and the deposition of lipids, cholesterol, calcium, and cellular debris within the vessel wall intima. In-depth studies of gut flora in recent years have shown that bacterial translocation and the existence of bacterial active products in blood circulation can affect the inflammatory state of the whole blood vessel. The gut flora is considered to be a large “secretory organ,” which produces trimethylamine-N-oxide (TMAO), short-chain fatty acids and secondary bile acids by breaking down the ingested food. Studies have shown that TMAO is an independent risk factor for the occurrence of malignant adverse cardiovascular events, but whether it is harmful or beneficial to patients with cardiovascular diseases with mild or no clinical manifestations remains controversial. We review the relationship between TMAO and its precursor (L-carnitine) and coronary atherosclerosis and summarize the potential molecular mechanism and therapeutic measures of TMAO on coronary atherosclerosis.

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

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

Gut microbiota, dysbiosis and atrial fibrillation. Arrhythmogenic mechanisms and potential clinical implications

Recent preclinical and observational cohort studies have implicated imbalances in gut microbiota composition as a contributor to atrial fibrillation (AF). The gut microbiota is a complex and dynamic ecosystem containing trillions of microorganisms, which produces bioactive metabolites influencing host health and disease development. In addition to host-specific determinants, lifestyle-related factors such as diet and drugs are important determinants of the gut microbiota composition. In this review, we discuss the evidence suggesting a potential bidirectional association between AF and gut microbiota, identifying gut microbiota-derived metabolites as possible regulators of the AF substrate. We summarize the effect of gut microbiota on the development and progression of AF risk-factors, including heart failure, hypertension, obesity and coronary artery disease. We also discuss the potential antiarrhythmic effects of pharmacological and diet-induced modifications of gut microbiota composition, which may modulate and prevent the progression to AF. Finally, we highlight important gaps in knowledge and areas requiring future investigation. Although data supporting a direct relationship between gut microbiota and AF are very limited at the present time, emerging preclinical and clinical research dealing with mechanistic interactions between gut microbiota and AF is important as it may lead to new insights into AF pathophysiology and the discovery of novel therapeutic targets for AF.