Trimethylamine N-oxide Production Research Articles

Metabolomic and genomic insights into TMA degradation by a novel halotolerant strain - Paracoccus sp. PS1.

Trimethylamine N-oxide (TMAO) is a gut metabolite that acts as a biomarker for chronic diseases, and is generated by the oxidation of trimethylamine (TMA) produced by gut microflora. Since, microbial degradation of TMA is predicted to be used to restrict the production of TMAO, we aimed to isolate bacterial strains that could effectively degrade TMA before being oxidized to TMAO. As marine fish is considered to have a rich content of TMAO, we have isolated TMA degrading isolates from fish skin. Out of the fourteen isolates, depending on their rapid TMA utilization capability in mineral salt medium supplemented with TMA as a sole carbon and nitrogen source, isolate PS1 was selected as our desired isolate. Its TMA degrading capacity was further confirmed through spectrophotometric, Electrospray Ionization Time-of-Flight Mass Spectrometry (ESI TOF-MS) and High performance liquid chromatography (HPLC) analysis and in silico analysis of whole genome (WG) gave further insights of protein into its TMA degradation pathways. PS1 was taxonomically identified as Paracoccus sp. based on its 16S rRNA and whole genome sequence analysis. As PS1 possesses the enzymes required for degradation of TMA, clinical use of this isolate has the potential to reduce TMAO generation in the human gut.

Trimethylamine N-oxide impairs β-cell function and glucose tolerance

β-Cell dysfunction and β-cell loss are hallmarks of type 2 diabetes (T2D). Here, we found that trimethylamine N-oxide (TMAO) at a similar concentration to that found in diabetes could directly decrease glucose-stimulated insulin secretion (GSIS) in MIN6 cells and primary islets from mice or humans. Elevation of TMAO levels impairs GSIS, β-cell proportion, and glucose tolerance in male C57BL/6 J mice. TMAO inhibits calcium transients through NLRP3 inflammasome-related cytokines and induced Serca2 loss, and a Serca2 agonist reversed the effect of TMAO on β-cell function in vitro and in vivo. Additionally, long-term TMAO exposure promotes β-cell ER stress, dedifferentiation, and apoptosis and inhibits β-cell transcriptional identity. Inhibition of TMAO production improves β-cell GSIS, β-cell proportion, and glucose tolerance in both male db/db and choline diet-fed mice. These observations identify a role for TMAO in β-cell dysfunction and maintenance, and inhibition of TMAO could be an approach for the treatment of T2D.

Trimethylamine N-oxide generation process was influenced by the proportion and source of macronutrients in the diet

Trimethylamine N-oxide (TMAO) is a risk factor of various chronic diseases, which was produced by metabolism from precursors to trimethylamine (TMA) in gut and the oxidation from TMA in liver. The TMA generation was influenced by diet, mainly due to the rich TMAO precursors in diet. However, it was still unclear that the effects of different proportion and source of macronutrients in different dietary pattern on the production process of TMAO. Here, the generation of TMA from precursors and TMAO from TMA was determined after single oral choline chloride and intraperitoneal injection TMA, respectively, in mice fed with carbohydrates, proteins and fats in different proportion and sources. The results suggested that the generation of TMAO was increased by low non-meat protein and high fat via enhancing the production of TMAO from TMA, and decreased by plant protein and refined sugar via reducing TMA production from precursors in gut and TMAO transformation from TMA in liver. The high fat and high sugar diets accelerating the development of atherosclerosis did not increase the production of TMAO, the risk factor for atherosclerosis, which indicated that the dietary compositions rather than the elevated TMAO level might be a more key risk factor for atherosclerosis.

Identification of Polymethoxyflavones (PMFs) from Orange Peel and Their Inhibitory Effects on the Formation of Trimethylamine (TMA) and Trimethylamine-N-oxide (TMAO) Using cntA/B and cutC/D Enzymes and Molecular Docking.

This study investigates the inhibitory effects of polymethoxyflavones (PMFs) on enzymes involved in the production of trimethylamine (TMA) and trimethylamine-N-oxide (TMAO). PMFs were isolated from Valencia orange peel and identified using column separation and NMR techniques. The findings reveal that nobiletin and 3,6,7,8,2',5'-hexamethoxyflavone significantly suppress cntA/B and cutC/D, respectively. Furthermore, 3,6,7,8,2',5'-hexamethoxyflavone decreases the level of TMAO formation by suppressing the FMO3 mRNA level. This study elucidates that specific structural features of PMFs can contribute to their interactions with enzymes. Our study represents the first demonstration of the ability of PMFs to mitigate the risk of cardiovascular disease (CVD) by inhibiting enzymes responsible for TMA production, which are generated by gut microbiomes. Furthermore, we introduce a novel model system utilizing TMA-induced HepG2 cells to assess and compare the inhibitory effects of PMFs on TMAO production. These findings could pave the way for the development of novel therapeutic approaches to manage CVD.

Metaorganismal choline metabolism shapes olfactory perception

Microbes living in the intestine can regulate key signaling processes in the central nervous system that directly impact brain health. This gut-brain signaling axis is partially mediated by microbe-host-dependent immune regulation, gut-innervating neuronal communication, and endocrine-like small molecule metabolites that originate from bacteria to ultimately cross the blood-brain barrier. Given the mounting evidence of gut-brain crosstalk, a new therapeutic approach of "psychobiotics" has emerged, whereby strategies designed to primarily modify the gut microbiome have been shown to improve mental health or slow neurodegenerative diseases. Diet is one of the most powerful determinants of gut microbiome community structure, and dietary habits are associated with brain health and disease. Recently, the metaorganismal (i.e., diet-microbe-host) trimethylamine N-oxide (TMAO) pathway has been linked to the development of several brain diseases including Alzheimer's, Parkinson's, and ischemic stroke. However, it is poorly understood how metaorganismal TMAO production influences brain function under normal physiological conditions. To address this, here we have reduced TMAO levels by inhibiting gut microbe-driven choline conversion to trimethylamine (TMA), and then performed comprehensive behavioral phenotyping in mice. Unexpectedly, we find that TMAO is particularly enriched in the murine olfactory bulb, and when TMAO production is blunted at the level of bacterial choline TMA lyase (CutC/D), olfactory perception is altered. Taken together, our studies demonstrate a previously underappreciated role for the TMAO pathway in olfactory-related behaviors.

Dietary phenolics and their microbial metabolites are poor inhibitors of trimethylamine oxidation to trimethylamine N-oxide by hepatic flavin monooxygenase 3

High circulating levels of trimethylamine N-oxide (TMAO) have been associated with cardiovascular disease risk. TMAO is formed through a microbiome-host pathway utilizing primarily dietary choline as a substrate. Specific gut microbiota transform choline into trimethylamine (TMA), and, when absorbed, host hepatic flavin-containing monooxygenase 3 (FMO3) oxidizes TMA into TMAO. Chlorogenic acid and its metabolites reduce microbial TMA production in vitro. However, little is known regarding the potential for chlorogenic acid and its bioavailable metabolites to inhibit the last step: hepatic conversion of TMA to TMAO. We developed a screening methodology to study FMO3-catalyzed production of TMAO from TMA. HepG2 cells were unable to oxidize TMA into TMAO due to their lack of FMO3 expression. Although Hepa-1 cells did express FMO3 when pretreated with TMA and NADPH, they lacked enzymatic activity to produce TMAO. Rat hepatic microsomes contained active FMO3. Optimal reaction conditions were: 50 µM TMA, 0.2 mM NADPH, and 33 µL microsomes/mL reaction. Methimazole (a known FMO3 competitive substrate) at 200 µM effectively reduced FMO3-catalyzed conversion of TMA to TMAO. However, bioavailable chlorogenic acid metabolites did not generally inhibit FMO3 at physiological (1 µM) nor supra-physiological (50 µM) doses. Thus, the effects of chlorogenic acid in regulating TMAO levels in vivo are unlikely to occur through direct FMO3 enzyme inhibition. Potential effects on FMO3 expression remain unknown. Intestinal inhibition of TMA production and/or absorption are thus likely their primary mechanisms of action.

Meta-analysis of the impact of bariatric surgery on circulating TMAO levels as a predictor of cardiovascular disease risk.

Trimethylamine N-oxide (TMAO) is a metabolite of the gut microbiota that is considered a cardiovascular risk factor. Because bariatric surgery (BS) produces changes in the composition of the gut microbiota, the production of TMAO can be compromised. Thus, the purpose of this meta-analysis was to determine the effect of BS on circulating TMAO levels. A systematic search was carried on in Embase, PubMed, Web of Science, and Scopus databases. The meta-analysis was conducted using Comprehensive Meta-Analysis (CMA) V2 software. The overall effect size was determined by a random-effects meta-analysis and the leave-one-out approach. Random-effects meta-analysis of 5 studies consisting of 142 subjects demonstrated a significant increase in circulating TMAO levels after BS (SMD: 1.190, 95% CI: 0.521, 1.858, p<0.001; I2:89.30%). Considering that levels of TMAO are affected after BS due to gut microbial metabolism alteration, there has been a significant elevation in TMAO concentrations observed to occur after BS in obese subjects.

Trimethylamine-N-oxide: a potential biomarker and therapeutic target in ischemic stroke.

Ischemic stroke is by far the most common cerebrovascular disease and a major burden to the global economy and public health. Trimethylamine-N-oxide (TMAO), a small molecule compound produced by the metabolism of intestinal microorganisms, is reportedly associated with the risk of stroke, as well as the severity and prognosis of stroke; however, this conclusion remains contentious. This article reviews the production of TMAO, TMAO's relationship with different etiological types of ischemic stroke, and the possibility of reducing TMAO levels to improve the prognosis of ischemic stroke.

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

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

Probiotics as potential treatments to reduce myocardial remodelling and heart failure via the gut-heart axis: State-of-the-art review.

Probiotics are considered to represent important modulators of gastrointestinal health through increased colonization of beneficial bacteria thus altering the gut microflora. Although these beneficial effects of probiotics are now widely recognized, emerging evidence suggests that alterations in the gut microflora also affect numerous other organ systems including the heart through a process generally referred to as the gut-heart axis. Moreover, cardiac dysfunction such as that seen in heart failure can produce an imbalance in the gut flora, known as dysbiosis, thereby further contributing to cardiac remodelling and dysfunction. The latter occurs by the production of gut-derived pro-inflammatory and pro-remodelling factors which exacerbate cardiac pathology. One of the key contributors to gut-dependent cardiac pathology is trimethylamine N-oxide (TMAO), a choline and carnitine metabolic by-product first synthesized as trimethylamine which is then converted into TMAO by a hepatic flavin-containing monooxygenase. The production of TMAO is particularly evident with regular western diets containing high amounts of both choline and carnitine. Dietary probiotics have been shown to reduce myocardial remodelling and heart failure in animal models although the precise mechanisms for these effects are not completely understood. A large number of probiotics have been shown to possess a reduced capacity to synthesize gut-derived trimethylamine and therefore TMAO thereby suggesting that inhibition of TMAO is a factor mediating the beneficial cardiac effects of probiotics. However, other potential mechanisms may also be important contributing factors. Here, we discuss the potential benefit of probiotics as effective therapeutic tools for attenuating myocardial remodelling and heart failure.

Gut Microbiota and Coronary Artery Disease: Current Therapeutic Perspectives.

The human gut microbiota is the community of microorganisms living in the human gut. This microbial ecosystem contains bacteria beneficial to their host and plays important roles in human physiology, participating in energy harvest from indigestible fiber, vitamin synthesis, and regulation of the immune system, among others. Accumulating evidence suggests a possible link between compositional and metabolic aberrations of the gut microbiota and coronary artery disease in humans. Manipulating the gut microbiota through targeted interventions is an emerging field of science, aiming at reducing the risk of disease. Among the interventions with the most promising results are probiotics, prebiotics, synbiotics, and trimethylamine N-oxide (TMAO) inhibitors. Contemporary studies of probiotics have shown an improvement of inflammation and endothelial cell function, paired with attenuated extracellular matrix remodeling and TMAO production. Lactobacilli, Bifidobacteria, and Bacteroides are some of the most well studied probiotics in experimental and clinical settings. Prebiotics may also decrease inflammation and lead to reductions in blood pressure, body weight, and hyperlipidemia. Synbiotics have been associated with an improvement in glucose homeostasis and lipid abnormalities. On the contrary, no evidence yet exists on the possible benefits of postbiotic use, while the use of antibiotics is not warranted, due to potentially deleterious effects. TMAO inhibitors such as 3,3-dimethyl-1-butanol, iodomethylcholine, and fluoromethylcholine, despite still being investigated experimentally, appear to possess anti-inflammatory, antioxidant, and anti-fibrotic properties. Finally, fecal transplantation carries conflicting evidence, mandating the need for further research. In the present review we summarize the links between the gut microbiota and coronary artery disease and elaborate on the varied therapeutic measures that are being explored in this context.

Microbiota Effect on Trimethylamine N-Oxide Production: From Cancer to Fitness-A Practical Preventing Recommendation and Therapies.

Trimethylamine N-oxide (TMAO) is a microbial metabolite derived from nutrients, such as choline, L-carnitine, ergothioneine and betaine. Recently, it has come under the spotlight for its close interactions with gut microbiota and implications for gastrointestinal cancers, cardiovascular disease, and systemic inflammation. The culprits in the origin of these pathologies may be food sources, in particular, high fat meat, offal, egg yolk, whole dairy products, and fatty fish, but intercalated between these food sources and the production of pro-inflammatory TMAO, the composition of gut microbiota plays an important role in modulating this process. The aim of this review is to explain how the gut microbiota interacts with the conversion of specific compounds into TMA and its oxidation to TMAO. We will first cover the correlation between TMAO and various pathologies such as dysbiosis, then focus on cardiovascular disease, with a particular emphasis on pro-atherogenic factors, and then on systemic inflammation and gastrointestinal cancers. Finally, we will discuss primary prevention and therapies that are or may become possible. Possible treatments include modulation of the gut microbiota species with diets, physical activity and supplements, and administration of drugs, such as metformin and aspirin.

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

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

PS-BPB09-5: BROWN ADIPOSE TISSUE DYSFUNCTION PROMOTES METABOLIC DISORDER IN A FAILING HEART.

Objective: Low body temperature predicts poor clinical outcomes in patients with heart failure, however, underlying mechanisms and pathological implications are largely unknown. Brown adipose tissue (BAT) was initially characterized as a heat generating organ, and studies suggest it has crucial roles for maintaining systemic metabolic health. The purpose of this study was to determine whether alteration of BAT function contributes to development of heart failure. Design and method: We generated two murine heart failure models, thoracic aortic constriction (TAC) and myocardial infarction (MI). We analyzed cardiac function, thermogenic response, and pathological findings in the hearts of these mice. We also performed comprehensive metabolomic analyses in the heart, BAT, and plasma samples from sham- and TAC-operated mice. Results: We found murine models with TAC or MI induced BAT dysfunction, and this led to a significant reduction in body temperature. Chronic activation of adrenergic signaling induced apoptosis in brown adipocytes, and surgical denervation of sympathetic nerves innervating BAT improved thermogenic response and cardiac systolic dysfunction. Gain of BAT function model, generated with BAT implantation into peritoneal cavity, improved thermogenesis and ameliorated cardiac dysfunction in TAC. In contrast, systolic function was reduced in genetically BAT dysfunctional model, and this associated with poor survival rate in this model. Metabolomic analyses showed that BAT dysfunction led to an increase of choline and its downstream metabolite, trimethylamine N-oxide (TMAO) that promoted metabolic dysfunction in the failing heart. TMAO administration resulted in a significant reduction in phosphocreatine or ATP level in cardiac tissues, and this was mediated by the suppression of complex IV activity in mitochondria. Genetic or pharmacological inhibition of TMAO production ameliorated cardiac dysfunction during left ventricular pressure overload. Dilated cardiomyopathy patients had lower body temperature, and this associated with an increase in circulating choline and TMAO level. Conclusions: Alteration of BAT function contributes to the development of heart failure via increased TMAO. Our findings suggest that maintenance of BAT homeostasis and reducing TMAO production could be potential next-generation therapies for heart failure.

Intestinal Flora Derived Metabolites Affect the Occurrence and Development of Cardiovascular Disease.

In recent years, increasing evidence has shown that the gut microbiota and their metabolites play a pivotal role in human health and diseases, especially the cardiovascular diseases (CVDs). Intestinal flora imbalance (changes in the composition and function of intestinal flora) accelerates the progression of CVDs. The intestinal flora breaks down the food ingested by the host into a series of metabolically active products, including trimethylamine N-Oxide (TMAO), short-chain fatty acids (SCFAs), primary and secondary bile acids, tryptophan and indole derivatives, phenylacetylglutamine (PAGln) and branched chain amino acids (BCAA). These metabolites participate in the occurrence and development of CVDs via abnormally activating these signaling pathways more swiftly when the gut barrier integrity is broken down. This review focuses on the production and metabolism of TMAO and SCFAs. At the same time, we summarize the roles of intestinal flora metabolites in the occurrence and development of coronary heart disease and hypertension, pulmonary hypertension and other CVDs. The theories of "gut-lung axis" and "gut-heart axis" are provided, aiming to explore the potential targets for the treatment of CVDs based on the roles of the intestinal flora in the CVDs.

Melatonin relieves hepatic lipid dysmetabolism caused by aging via modifying the secondary bile acid pattern of gut microbes.

It has been reported that aging-generated gut microecosystem may promote host hepatic lipid dysmetabolism through shaping the pattern of secondary bile acids (BAs). Then as an oral drug, melatonin (Mel)-mediated beneficial efforts on the communication between gut microbiota and aging host are still not clearly. Here, we show that aging significantly shapes the pattern of gut microbiota and BAs, whereas Mel treatment reverses these phenotypes (P < 0.05), which is identified to depend on the existence of gut microbiota. Mechanistically, aging-triggered high-level expression of ileac farnesoid X receptor (FXR) is significantly decreased through Mel-mediated inhibition on Campylobacter jejuni (C. jejuni)-induced deconjugation of tauroursodeoxycholic acid (TUDCA) and glycoursodeoxycholic acid (GUDCA) (P < 0.05). The aging-induced high-level of serum taurine chenodeoxycholic acid (TCDCA) activate trimethylamine-N-oxide (TMAO)-triggered activating transcriptional factor 4 (ATF4) signaling via hepatic FXR, which further regulates hepatic BAs metabolism, whereas TUDCA inhibits aging-triggered high-level of hepatic ATF4. Overall, Mel reduces C. jejuni-mediated deconjugation of TUDCA to inhibit aging-triggered high-level expression of hepatic FXR, which further decreases hepatic TMAO production, to relieve hepatic lipid dysmetabolism.

Brown adipose tissue dysfunction promotes heart failure via a trimethylamine N-oxide-dependent mechanism

Low body temperature predicts a poor outcome in patients with heart failure, but the underlying pathological mechanisms and implications are largely unknown. Brown adipose tissue (BAT) was initially characterised as a thermogenic organ, and recent studies have suggested it plays a crucial role in maintaining systemic metabolic health. While these reports suggest a potential link between BAT and heart failure, the potential role of BAT dysfunction in heart failure has not been investigated. Here, we demonstrate that alteration of BAT function contributes to development of heart failure through disorientation in choline metabolism. Thoracic aortic constriction (TAC) or myocardial infarction (MI) reduced the thermogenic capacity of BAT in mice, leading to significant reduction of body temperature with cold exposure. BAT became hypoxic with TAC or MI, and hypoxic stress induced apoptosis of brown adipocytes. Enhancement of BAT function improved thermogenesis and cardiac function in TAC mice. Conversely, systolic function was impaired in a mouse model of genetic BAT dysfunction, in association with a low survival rate after TAC. Metabolomic analysis showed that reduced BAT thermogenesis was associated with elevation of plasma trimethylamine N-oxide (TMAO) levels. Administration of TMAO to mice led to significant reduction of phosphocreatine and ATP levels in cardiac tissue via suppression of mitochondrial complex IV activity. Genetic or pharmacological inhibition of flavin-containing monooxygenase reduced the plasma TMAO level in mice, and improved cardiac dysfunction in animals with left ventricular pressure overload. In patients with dilated cardiomyopathy, body temperature was low along with elevation of plasma choline and TMAO levels. These results suggest that maintenance of BAT homeostasis and reducing TMAO production could be potential next-generation therapies for heart failure.

Gut-Flora-Dependent Metabolite Trimethylamine-N-Oxide Promotes Atherosclerosis-Associated Inflammation Responses by Indirect ROS Stimulation and Signaling Involving AMPK and SIRT1.

Trimethylamine-N-oxide (TMAO), a gut-microbiota-dependent metabolite after ingesting dietary choline, has been identified as a novel risk factor for atherosclerosis through inducing vascular inflammation. However, the underlying molecular mechanism is poorly understood. Using an in vitro vascular cellular model, we found that the TMAO-induced inflammation responses were correlated with an elevation of ROS levels and downregulation of SIRT1 expression in VSMCs and HUVECs. The overexpression of SIRT1 could abrogate both the stimulation of ROS and inflammation. Further studies revealed that AMPK was also suppressed by TMAO and was a mediator upstream of SIRT1. Activation of AMPK by AICAR could reduce TMAO-induced ROS and inflammation. Moreover, the GSH precursor NAC could attenuate TMAO-induced inflammation. In vivo studies with mice models also showed that choline-induced production of TMAO and the associated glycolipid metabolic changes leading to atherosclerosis could be relieved by NAC and a probiotic LP8198. Collectively, the present study revealed an unrecognized mechanistic link between TMAO and atherosclerosis risk, and probiotics ameliorated TMAO-induced atherosclerosis through affecting the gut microbiota. Consistent with previous studies, our data confirmed that TMAO could stimulate inflammation by modulating cellular ROS levels. However, this was not due to direct cytotoxicity but through complex signaling pathways involving AMPK and SIRT1.

Influence of Gut Microbiota and Trimethylamine N-Oxide in Patients with Coronary Heart Disease.

In the current study, the gut microbiota of patients with and without coronary heart disease was compared and the relationship between gut microbiota distribution, intending to reveal the role of gut microbiota in the coronary atherosclerosis process, was investigated.This study included 50 patients diagnosed with coronary heart disease (CHD) who received conventional coronary angiography or computed tomography angiography and 50 patients with CHD at Changshu No. 2 People's Hospital, Suzhou, China, from May 2020 to January 2021. Trimethylamine N-oxide (TMAO) level was tested and feces were collected, the DNA of the gut microbiota was extracted, and the distribution by 16SrRNA gene sequencing was obtained from the two groups of patients.Plasma TMAO concentrations were significantly higher in patients with CHD (P < 0.001). In the CHD group, 22 patients with multivessel disease had a higher level of TMAO compared with the 28 patients who had the single-vessel disease (P < 0.001). No difference in the gut microbiota diversity was noted between the two groups (P < 0.001). Patients with CHD had a significantly lower proportion of Bacteroidetes phyla and more proportion of Epsilonbacteraeota phyla. At the genus level, patients with CHD had an increased abundance of Enterococcus, whereas healthy controls had significantly higher levels of Streptococcus. Phylogenetic Investigation of Communities by Reconstruction of Unobserved States 2 analysis found that, in the KEGG ORTHOLOGY, the level of choline trimethylamine-lyase gene expression correlated with TMAO production was higher in the fecal microbiome of the CHD group (P < 0.05).Gut microbiota and its product were expected to become a diagnostic marker and a new target for preventing CHD.

Berberine treats atherosclerosis via a vitamine-like effect down-regulating Choline-TMA-TMAO production pathway in gut microbiota

Trimethylamine-N-oxide (TMAO) derived from the gut microbiota is an atherogenic metabolite. This study investigates whether or not berberine (BBR) could reduce TMAO production in the gut microbiota and treat atherosclerosis. Effects of BBR on TMAO production in the gut microbiota, as well as on plaque development in atherosclerosis were investigated in the culture of animal intestinal bacterial, HFD-fed animals and atherosclerotic patients, respectively. We found that oral BBR in animals lowers TMAO biosynthesis in intestine through interacting with the enzyme/co-enzyme of choline-trimethylamine lyase (CutC) and flavin-containing monooxygenase (FMO) in the gut microbiota. This action was performed by BBR’s metabolite dihydroberberine (a reductive BBR by nitroreductase in the gut microbiota), via a vitamine-like effect down-regulating Choline-TMA-TMAO production pathway. Oral BBR decreased TMAO production in animal intestine, lowered blood TMAO and interrupted plaque formation in blood vessels in the HFD-fed hamsters. Moreover, 21 patients with atherosclerosis exhibited the average decrease of plaque score by 3.2% after oral BBR (0.5 g, bid) for 4 months (*P < 0.05, n = 21); whereas the plaque score in patients treated with rosuvastatin plus aspirin, or clopidogrel sulfate or ticagrelor (4 months, n = 12) increased by 1.9%. TMA and TMAO in patients decreased by 38 and 29% in faeces (*P < 0.05; *P < 0.05), and 37 and 35% in plasma (***P < 0.001; *P < 0.05), after 4 months on BBR. BBR might treat atherosclerotic plaque at least partially through decreasing TMAO in a mode of action similar to that of vitamins.