Intestinal microbiota metabolism of L-carnitine, a nutrient in red meat, promotes atherosclerosis

Liver as a new target organ in Alzheimer's disease: insight from cholesterol metabolism and its role in amyloid-beta clearance

Alzheimer's disease, the primary cause of dementia, is characterized by neuropathologies, such as amyloid plaques, synaptic and neuronal degeneration, and neurofibrillary tangles. Although amyloid plaques are the primary characteristic of Alzheimer's disease in the central nervous system and peripheral organs, targeting amyloid-beta clearance in the central nervous system has shown limited clinical efficacy in Alzheimer's disease treatment. Metabolic abnormalities are commonly observed in patients with Alzheimer's disease. The liver is the primary peripheral organ involved in amyloid-beta metabolism, playing a crucial role in the pathophysiology of Alzheimer's disease. Notably, impaired cholesterol metabolism in the liver may exacerbate the development of Alzheimer's disease. In this review, we explore the underlying causes of Alzheimer's disease and elucidate the role of the liver in amyloid-beta clearance and cholesterol metabolism. Furthermore, we propose that restoring normal cholesterol metabolism in the liver could represent a promising therapeutic strategy for addressing Alzheimer's disease.

TMAO induces pyroptosis of vascular endothelial cells and atherosclerosis in ApoE-/- mice via MBOAT2-mediated endoplasmic reticulum stress

Trimethylamine N-oxide (TMAO), a metabolite produced by intestinal flora, is recognized as an independent risk factor for atherosclerosis and atherosclerotic cardiovascular diseases. However, the underlying mechanism remains poorly understood. Here, we showed that dietary TMAO supplementation accelerates atherosclerosis in ApoE-/- mice. Pyroptosis and the expression of phospholipid-modifying enzyme MBOAT2 were increased in endothelial cells within atherosclerotic lesions. Genetic upregulation of MBOAT2 via adeno-associated virus with endothelium-specific promoter results in increased atherosclerotic lesions in ApoE-/- mice. Mechanistically, the overexpression of MBOAT2 disrupted glycerophospholipid metabolism and induced endothelial cell pyroptosis in an Endoplasmic reticulum stress-dependent manner. These data reveal that TMAO promotes endothelial cell pyroptosis and the progression of atherosclerotic lesions through the upregulation of MBOAT2, indicating that MBOAT2 is a promising therapeutic target for atherosclerosis.

Trimethylamine N-oxide detection by electrochemical sensor based on screen printed electrode modified with molecularly imprinted polypyrrole-molybdenum(III) sulfide nanosheets

Trimethylamine N-oxide (TMAO) is a gut metabolite produced by dietary L-carnitine and choline metabolism. Its altered level in the serum has been implicated in human health and diseases such as colorectal cancer, chronic kidney diseases, cardiovascular diseases, etc. Early detection of TMAO in body fluids has been presumed to be significant in understanding the pathogenesis and treatment of many diseases. Hence, developing reliable and rapid technologies for its detection may augment our understanding of pathogenesis and diagnosis of diseases. Hence, in the present work, polypyrrole (Ppy)@molybdenum(III)sulfide (Mo2S3) nanosheets (NS) composite molecularly imprinted polymer (MIP) (Ppy@Mo2S3-MIP) based electrochemical sensor has been fabricated for the detection of TMAO. Polypyrrole (Ppy) and Mo2S3 NS have been synthesized by chemical oxidative polymerization and hydrothermal techniques, respectively. The synthesized nanocomposite has been validated using different techniques such as X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The fabricated Ppy@Mo2S3-MIP sensor showed a linear detection range from 30 µM to 210 µM, a sensitivity of 1.21 μA μM-1 cm-2 and a limit of detection as 1.4 μM for the detection of TMAO and found more robust and improved when compared with Ppy-MIP using identical parameters. The fabricated sensor is also highly selective towards TMAO. It can be further used to detect TMAO in human samples such as urine quickly.

Gut microbiota: Implications in pathogenesis and therapy to cardiovascular disease (Review)

The gut microbiota refers to the diverse bacterial community residing in the gastrointestinal tract. Recent data indicate a strong correlation between alterations in the gut microbiota composition and the onset of various diseases, notably cardiovascular disorders. Evidence suggests the gut-cardiovascular axis signaling molecules released by the gut microbiota play a pivotal role in regulation. This review systematically delineates the association between dysbiosis of the gut microbiota and prevalent cardiovascular diseases, including atherosclerosis, hypertension, myocardial infarction and heart failure. Furthermore, it provides an overview of the putative pathogenic mechanisms by which dysbiosis in the gut microbiota contributes to the progression of cardiovascular ailments. The potential modulation of gut microbiota as a preventive strategy against cardiovascular diseases through dietary interventions, antibiotic therapies and probiotic supplementation is also explored and discussed within the present study.

Dietary Dihydroquercetin Alleviated Colitis via the Short-Chain Fatty Acids/miR-10a-5p/PI3K-Akt Signaling Pathway

Gut microbiota provides an important insight into clarifying the mechanism of active substances with low bioavailability, but its specific action mechanism varied case by case and remained unclear. Dihydroquercetin (DHQ) is a bioactive flavonoid with low bioavailability, which showed beneficial effects on colitis alleviation and gut microbiota modulation. Herein, we aimed to explore the microbiota-dependent anticolitis mechanism of DHQ in sight of gut microbiota metabolites and their interactions with microRNAs (miRNAs). Dietary supplementation of DHQ alleviated dextran sulfate sodium-induced colitis phenotypes and improved gut microbiota dysbiosis. Fecal microbiota transplantation further revealed that the anticolitis activity of DHQ was mediated by gut microbiota. To clarify how the modulated gut microbiota alleviated colitis in mice, the tandem analyses of the microbiome and targeted metabolome were performed, and altered profiles of metabolite short-chain fatty acids (SCFAs) and bile acids and their producers were observed in DHQ-treated mice. In addition, SCFA treatment showed anticolitis activity compared to that of bile acids, along with the specific inhibition on the phosphoinositide-3-kinase (PI3K)-protein kinase B (Akt) pathway. Subsequently, the colonic miRNA profile of mice receiving SCFA treatment was sequenced, and a differentially expressed miR-10a-5p was identified. Both prediction analysis and dual-luciferase reporter assay indicated that miR-10a-5p directly bind to the 3'-untranslated regions of gene pik3ca, inhibit the PI3K-Akt pathway activation, and lead to colitis alleviation. Together, we proposed that gut microbiota mediated the anticolitis activity of DHQ through the SCFAs/miR-10a-5p/PI3K-Akt axis, and it provided a novel insight into clarifying the microbiota-dependent mechanism via the interaction between metabolites and miRNAs.

Gut microbiota-related modulation of immune mechanisms in post-infarction remodelling and heart failure

The immune system has long been recognized as a key driver in the progression of heart failure (HF). However, clinical trials targeting immune effectors have consistently failed to improve patient outcome across different HF aetiologies. The activation of the immune system in HF is complex, involving a broad network of pro-inflammatory and immune-modulating components, which complicates the identification of specific immune pathways suitable for therapeutic targeting. Increasing attention has been devoted to identifying gut microbial pathways that affect cardiac remodelling and metabolism and, thereby impacting the development of HF. In particular, gut microbiota-derived metabolites, absorbed by the host and transported to the peripheral circulation, can act as signalling molecules, influencing metabolism and immune homeostasis. Recent reports suggest that the gut microbiota plays a crucial role in modulating immune processes involved in HF. Here, we summarize recent advances in understanding the contributory role of gut microbiota in (auto-)immune pathways that critically determine the progression or alleviation of HF. We also thoroughly discuss potential gut microbiota-based intervention strategies to treat or decelerate HF progression.

Flavonoids, gut microbiota and cardiovascular disease: Dynamics and interplay

Cardiovascular disease (CVD) remains the leading cause of global morbidity and mortality. Extensive efforts have been invested to explicate mechanisms implicated in the onset and progression of CVD. Besides the usual suspects as risk factors (obesity, diabetes, and others), the gut microbiome has emerged as a prominent and essential factor in the pathogenesis of CVD. With its endocrine-like effects, the microbiome modulates many physiologic processes. As such, it is not surprising that dysbiosis-by generating metabolites, inciting inflammation, and altering secondary bile acid signaling- could predispose to or aggravate CVD. Nevertheless, various natural and synthetic compounds have been shown to modulate the microbiome. Prime among these molecules are flavonoids, which are natural polyphenols mainly present in fruits and vegetables. Accumulating evidence supports the potential of flavonoids in attenuating the development of CVD. The ascribed mechanisms of these compounds appear to involve mitigation of inflammation, alteration of the microbiome composition, enhancement of barrier integrity, induction of reverse cholesterol transport, and activation of farnesoid X receptor signaling. In this review, we critically appraise the methods by which the gut microbiome, despite being essential to the human body, predisposes to CVD. Moreover, we dissect the mechanisms and pathways underlying the cardioprotective effects of flavonoids.

Aucubin ameliorates atherosclerosis by modulating tryptophan metabolism and inhibiting endothelial-mesenchymal transitions via gut microbiota regulation

BACKGROUND

The gut microbiota is believed to influence atherosclerosis (AS), and Aucubin (Au), a natural compound found in the traditional Chinese medicine Eucommia ulmoides Oliver, is being explored as a potential treatment for cardiovascular disease. Yet, the specific impact of Au on AS through the gut microbiota remains unclear.

PURPOSE

This study aimed to highlight the potential of Au in improving AS by influencing gut microbiota and investigating its potential mechanisms by which it and its metabolites of gut microbiota regulate lipid metabolism, inflammation and endothelial dysfunction.

METHODS

The impact of Au on AS in ApoE-/- mice was examined, followed by a fecal microbiota transplantation experiment to confirm the influence of Au on AS through gut microbiota. Subsequent analysis of fecal and serum samples using 16S rRNA gene sequencing and metabolomics revealed distinct features of gut microbiota and metabolites. Identified metabolites were then utilized in vivo experiments to investigate underlying mechanisms.

RESULTS

Au treatment effectively reduced dietary-induced dyslipidemia and endothelial dysfunction in a dose-dependent manner in atherosclerotic mice. It also improved vascular plaque accumulation and inflammation, increased aortic valve fibrous cap thickness, and decreased necrotic core and collagen fiber area. Subsequently, we observed a substantial increase in indole-3-acrylic acid (IAA), a microbe-derived metabolite, in cecal contents and serum, along with a significant rise in Lactobacillus abundance responsible for IAA production. Our findings demonstrated that IAA played a crucial role in alleviating AS. Furthermore, we discovered that IAA activated the Aryl hydrocarbon receptor (AhR) and suppressed the TGF-β/Smad pathway, potentially ameliorating endothelial-mesenchymal transitions in atherosclerotic mice.

CONCLUSION

These findings suggested that Au's anti-atherosclerotic effects were primarily due to elevated Lactobacillus-derived IAA, thereby potentially contributing to alleviating AS.

Impact of a legumes diet on the human gut microbiome articulated with fecal and plasma metabolomes: A pilot study

BACKGROUND & AIMS

Legumes intake is known to be associated with several health benefits the origins of which is still a matter of debate. This paper addresses a pilot small cohort to probe for metabolic aspects of the interplay between legumes intake, human metabolism and gut microbiota.

METHODS

Untargeted nuclear magnetic resonance (NMR) metabolomics of blood plasma and fecal extracts was carried out, in tandem with qPCR analysis of feces, to assess the impact of an 8-week pilot legumes diet intervention on the fecal and plasma metabolomes and gut microbiota of 19 subjects.

RESULTS

While the high inter-individual variability hindered the detection of statistically significant changes in the gut microbiome, increased fecal glucose and decreased threonine levels were noted. Correlation analysis between the microbiome and fecal metabolome lead to putative hypotheses regarding the metabolic activities of prevalent bacteria groups (Clostridium leptum subgroup, Roseburia spp., and Faecalibacterium prausnitzii). These included elevated fecal glucose as a preferential energy source, the involvement of valerate/isovalerate and reduced protein degradation in gut microbiota. Plasma metabolomics advanced mannose and betaine as potential markers of legume intake and unveiled a decrease in formate and ketone bodies, the latter suggesting improved energy utilization through legume carbohydrates. Amino acid metabolism was also apparently affected, as suggested by lowered urea, histidine and threonine levels.

CONCLUSIONS

Despite the high inter-individual gut microbiome variability characterizing the small cohort addressed, combination of microbiological measurements and untargeted metabolomics unveiled several metabolic effects putatively related to legumes intake. If confirmed in larger cohorts, our findings will support the inclusion of legumes in diets and contribute valuable new insight into the origins of associated health benefits.

Understanding the role of the human gut microbiome in overweight and obesity

The gut microbiome may be related to the prevalence of overweight and obesity, but high interindividual variability of the human microbiome complicates our understanding. Obesity often occurs concomitantly with micronutrient deficiencies that impair energy metabolism. Microbiota composition is affected by diet. Host-microbiota interactions are bidirectional. We propose three pathways whereby these interactions may modulate the gut microbiome and obesity: (1) ingested compounds or derivatives affecting small intestinal transit, endogenous secretions, digestion, absorption, microbiome balance, and gut barrier function directly affect host metabolism; (2) substrate availability affecting colonic microbial composition and contact with the gut barrier; and (3) microbial end products affecting host metabolism. The quantity/concentration, duration, and/or frequency (circadian rhythm) of changes in these pathways can alter the gut microbiome, disrupt the gut barrier, alter host immunity, and increase the risk of and progression to overweight and obesity. Host-specific characteristics (e.g., genetic variations) may further affect individual sensitivity and/or resilience to diet- and microbiome-associated perturbations in the colonic environment. In this narrative review, the effects of selected interventions, including fecal microbiota transplantation, dietary calorie restriction, dietary fibers and prebiotics, probiotics and synbiotics, vitamins, minerals, and fatty acids, on the gut microbiome, body weight, and/or adiposity are summarized to help identify mechanisms of action and research opportunities.

Intestinal microbiome as a diagnostic marker of coronary artery disease: a systematic review and meta-analysis

Background

The intestinal microbiome has been recently linked to several metabolic and chronic disorders, one of which is coronary artery disease (CAD). Our study aimed to analyze the intestinal microbiome of CAD patients and assess the eligibility of dysbiosis as a diagnostic marker of CAD.

Methods

PubMed, Scopus, Embase, and Web of Science were searched using terms, such as 'CAD' and 'microbiome'. Only observational controlled studies were included. R version 4.2.2 was used for the analysis.

Results

A significant association was found between the CAD group and increased Simpson and Shannon Indices compared with the control group (MD=0.04, 95% CI=0.03-0.05, and MD=0.11, 95% CI=0.01-0.22, respectively). Our analysis yielded a statistically significant association between the CAD group and increased Prevotella genus (MD=13.27, 95% CI=4.12-22.42, P-value=0.004), Catenibacterium genus (MD=0.09, 95% CI=0.09-0.10), Pseudomonas genus (MD=0.54, 95% CI=0.29-0.78, P-value), and Subdoligranulum (MD=-0.06, 95% CI=-0.06 to -0.06) compared with the control group. Another significant association was detected between the CAD group and decreased Bacteroides vulgatus and Bacteroides dorei (MD=-10.31, 95% CI=-14.78 to -5.84, P-value <0.00001).

Conclusion

Dysbiosis is an acceptable diagnostic marker of CAD. Decreased B. dorei and B. vulgatus among CAD patients suggests a protective role of these bacteria. Future clinical trials are necessary to investigate the potential benefit of supplementation of these bacteria in treating or preventing CAD.

The human gut microbiome in health and disease: time for a new chapter?

The gut microbiome, composed of the colonic microbiota and their host environment, is important for many aspects of human health. A gut microbiome imbalance (gut dysbiosis) is associated with major causes of human morbidity and mortality. Despite the central part our gut microbiome plays in health and disease, mechanisms that maintain homeostasis and properties that demarcate dysbiosis remain largely undefined. Here we discuss that sorting taxa into meaningful ecological units reveals that the availability of respiratory electron acceptors, such as oxygen, in the host environment has a dominant influence on gut microbiome health. During homeostasis, host functions that limit the diffusion of oxygen into the colonic lumen shelter a microbial community dominated by primary fermenters from atmospheric oxygen. In turn, primary fermenters break down unabsorbed nutrients into fermentation products that support host nutrition. This symbiotic relationship is disrupted when host functions that limit the luminal availability of host-derived electron acceptors become weakened. The resulting changes in the host environment drive alterations in the microbiota composition, which feature an elevated abundance of facultatively anaerobic microbes. Thus, the part of the gut microbiome that becomes imbalanced during dysbiosis is the host environment, whereas changes in the microbiota composition are secondary to this underlying cause. This shift in our understanding of dysbiosis provides a novel starting point for therapeutic strategies to restore microbiome health. Such strategies can either target the microbes through metabolism-based editing or strengthen the host functions that control their environment.

The association between the gut microbiota metabolite trimethylamine N-oxide and heart failure

This systematic review explores the relationship between the gut microbiota metabolite trimethylamine N-oxide (TMAO) and heart failure (HF), given the significant impact of TMAO on cardiovascular health. A systematic search and meta-analysis of peer-reviewed studies published from 2013 to 2024 were conducted, focusing on adult patients with heart failure and healthy controls. The review found that elevated levels of TMAO are associated with atherosclerosis, endothelial dysfunction, and increased cardiovascular disease risk, all of which can exacerbate heart failure. The analysis also highlights that high TMAO levels are linked to reduced left ventricular ejection fraction (LVEF) and glomerular filtration rate (GFR), further supporting TMAO's role as a biomarker in heart failure assessment. The findings suggest that interventions targeting gut microbiota to reduce TMAO could potentially benefit patients with heart failure, although further research is needed to evaluate the effectiveness of such approaches.

Role of Gut Microbial Metabolites in Cardiovascular Diseases-Current Insights and the Road Ahead

Cardiovascular diseases (CVDs) are the leading cause of premature morbidity and mortality globally. The identification of novel risk factors contributing to CVD onset and progression has enabled an improved understanding of CVD pathophysiology. In addition to the conventional risk factors like high blood pressure, diabetes, obesity and smoking, the role of gut microbiome and intestinal microbe-derived metabolites in maintaining cardiovascular health has gained recent attention in the field of CVD pathophysiology. The human gastrointestinal tract caters to a highly diverse spectrum of microbes recognized as the gut microbiota, which are central to several physiologically significant cascades such as metabolism, nutrient absorption, and energy balance. The manipulation of the gut microbial subtleties potentially contributes to CVD, inflammation, neurodegeneration, obesity, and diabetic onset. The existing paradigm of studies suggests that the disruption of the gut microbial dynamics contributes towards CVD incidence. However, the exact mechanistic understanding of such a correlation from a signaling perspective remains elusive. This review has focused upon an in-depth characterization of gut microbial metabolites and their role in varied pathophysiological conditions, and highlights the potential molecular and signaling mechanisms governing the gut microbial metabolites in CVDs. In addition, it summarizes the existing courses of therapy in modulating the gut microbiome and its metabolites, limitations and scientific gaps in our current understanding, as well as future directions of studies involving the modulation of the gut microbiome and its metabolites, which can be undertaken to develop CVD-associated treatment options. Clarity in the understanding of the molecular interaction(s) and associations governing the gut microbiome and CVD shall potentially enable the development of novel druggable targets to ameliorate CVD in the years to come.

The gut microbiota in thrombosis

The gut microbiota has emerged as an environmental risk factor that affects thrombotic phenotypes in several cardiovascular diseases. Evidence includes the identification of marker species by sequencing studies of the gut microbiomes of patients with thrombotic disease, the influence of antithrombotic therapies on gut microbial diversity, and preclinical studies in mouse models of thrombosis that have demonstrated the functional effects of the gut microbiota on vascular inflammatory phenotypes and thrombus formation. In addition to impaired gut barrier function promoting low-grade inflammation, gut microbiota-derived metabolites have been shown to act on vascular cell types and promote thrombus formation. Therefore, these meta-organismal pathways that link the metabolic capacities of gut microorganisms with host immune functions have emerged as potential diagnostic markers and novel drug targets. In this Review, we discuss the link between the gut microbiota, its metabolites and thromboembolic diseases.

Metabolic mediators: microbial-derived metabolites as key regulators of anti-tumor immunity, immunotherapy, and chemotherapy

The human microbiome has recently emerged as a focal point in cancer research, specifically in anti-tumor immunity, immunotherapy, and chemotherapy. This review explores microbial-derived metabolites, emphasizing their crucial roles in shaping fundamental aspects of cancer treatment. Metabolites such as short-chain fatty acids (SCFAs), Trimethylamine N-Oxide (TMAO), and Tryptophan Metabolites take the spotlight, underscoring their diverse origins and functions and their profound impact on the host immune system. The focus is on SCFAs' remarkable ability to modulate immune responses, reduce inflammation, and enhance anti-tumor immunity within the intricate tumor microenvironment (TME). The review critically evaluates TMAO, intricately tied to dietary choices and gut microbiota composition, assessing its implications for cancer susceptibility, progression, and immunosuppression. Additionally, the involvement of tryptophan and other amino acid metabolites in shaping immune responses is discussed, highlighting their influence on immune checkpoints, immunosuppression, and immunotherapy effectiveness. The examination extends to their dynamic interaction with chemotherapy, emphasizing the potential of microbial-derived metabolites to alter treatment protocols and optimize outcomes for cancer patients. A comprehensive understanding of their role in cancer therapy is attained by exploring their impacts on drug metabolism, therapeutic responses, and resistance development. In conclusion, this review underscores the pivotal contributions of microbial-derived metabolites in regulating anti-tumor immunity, immunotherapy responses, and chemotherapy outcomes. By illuminating the intricate interactions between these metabolites and cancer therapy, the article enhances our understanding of cancer biology, paving the way for the development of more effective treatment options in the ongoing battle against cancer.

Gut microbiota and myocardial infarction: A bibliometric analysis from 2004 to 2023

Background

In recent years, numerous studies have suggested that the gut microbiota and its metabolites are closely related to myocardial infarction. Utilizing insights from these research findings may be advantageous in the prevention, treatment, and prognosis of myocardial infarction. We have employed bibliometric methodology to summarize the progress made in this research area over the past 20 years, identify the hotspots, and highlight the developmental tendencies, providing a reference for future research in this field.

Methods

We searched the content related to this field in the Web of Science Core Collection database, with a time range from 2001 to 2023. We used VOSviewer, CiteSpace, and Scimago Graphica software to visualize the search results.

Results

We included 889 reports in this study. The country with the most publications was China, while the country with the greatest influence was the United States. An analysis of institutions showed that the Chinese Academy of Medical Sciences had the largest volume of publications, whereas the Cleveland Clinic had the most influential ones. An author analysis showed Stanley L Hazen to have published the most and to also have been the most influential researcher. An analysis of all the journals publishing articles related to the search terms showed that PLoS One journal had the highest number of publications (18 articles), while Atherosclerosis journal had the most influential articles. The results of our reference analysis showed a strong association between Trimethylamine N-oxide and myocardial infarction. We found that increased intestinal permeability may be related to the progression of cardiovascular diseases, a high-fiber diet may help in the prevention of diseases such as myocardial infarction, and populations with a high intake of red meat may have an increased risk of myocardial infarction. Keyword analysis suggested that 'cardiac fibrosis' and 'major bleeding' were promising research directions in the future, and supplementing food intake with short-chain fatty acids was looked upon as a promising approach to treating coronary heart disease.

Conclusion

The gut microbiota are closely related to myocardial infarction, and investigating this relationship is crucial for the prevention and treatment of myocardial infarction, where interdisciplinary research and international cooperation are indispensable.

Trimethylamine Oxidation into the Proatherogenic Trimethylamine N-Oxide Is Higher in Coronary Heart Disease Men: From the CORDIOPREV Study

PURPOSE

Cardiovascular disease (CVD) is more prevalent in men than women, but the mechanisms responsible for this are not fully understood. We aimed to evaluate differences in trimethylamine (TMA), a microbial metabolite and its oxidized form, trimethylamine N-oxide (TMAO), which is thought to promote atherosclerosis, between men and women with coronary heart disease (CHD), using as a reference a non-CVD population.

MATERIALS AND METHODS

This study was carried out within the framework of the CORDIOPREV study (NCT00924937; June 19, 2009), a clinical trial which included 827 men and 175 women with CHD, with a non-CVD population of 375 individuals (270 men and 105 women) as a reference group. Plasma TMA and TMAO were measured by HPLC-MS/MS. The carotid study was ultrasonically assessed bilaterally by the quantification of intima-media thickness of both common carotid arteries (IMT-CC).

RESULTS

We found higher TMAO levels and TMAO/TMA ratio in CHD men than CHD women (p=0.034 and p=0.026, respectively). No TMA sex differences were found in CHD patients. The TMA and TMAO levels and TMAO/TMA ratio were lower, and no differences between sexes were found in the non-CVD population. TMAO levels in CHD patients were consistent with higher IMT-CC and more carotid plaques (p=0.032 and p=0.037, respectively) and lower cholesterol efflux in CHD men than CHD women (p<0.001).

CONCLUSIONS

Our results suggest that CHD men have augmented TMAO levels compared with CHD women, presumably as a consequence of higher rate of TMA to TMAO oxidation, which could be associated with CVD, as these sex differences are not observed in a non-CVD population.

Targeting Gut Microbiota with Probiotics and Phenolic Compounds in the Treatment of Atherosclerosis: A Comprehensive Review

Atherosclerosis (AS) is a chronic inflammatory vascular disease. Dysregulated lipid metabolism, oxidative stress, and inflammation are the major mechanisms implicated in the development of AS. In addition, evidence suggests that gut dysbiosis plays an important role in atherogenesis, and modulation of the gut microbiota with probiotics and phenolic compounds has emerged as a promising strategy for preventing and treating AS. It has been shown that probiotics and phenolic compounds can improve atherosclerosis-related parameters by improving lipid profile, oxidative stress, and inflammation. In addition, these compounds may modulate the diversity and composition of the gut microbiota and improve atherosclerosis. The studies evaluated in the present review showed that probiotics and phenolic compounds, when consumed individually, improved atherosclerosis by modulating the gut microbiota in various ways, such as decreasing gut permeability, decreasing TMAO and LPS levels, altering alpha and beta diversity, and increasing fecal bile acid loss. However, no study was found that evaluated the combined use of probiotics and phenolic compounds to improve atherosclerosis. The available literature highlights the synergistic potential between phenolic compounds and probiotics to improve their health-promoting properties and functionalities. This review aims to summarize the available evidence on the individual effects of probiotics and phenolic compounds on AS, while providing insights into the potential benefits of nutraceutical approaches using probiotic strains, quercetin, and resveratrol as potential adjuvant therapies for AS treatment through modulation of the gut microbiota.

The Role of the Gut Microbiota in Complications among Hemodialysis Patients

The composition of the gut microbiota varies among end-stage renal disease (ESRD) patients on the basis of their mode of renal replacement therapy (RRT), with notably more pronounced dysbiosis occurring in those undergoing hemodialysis (HD). Interventions such as dialysis catheters, unstable hemodynamics, strict dietary restrictions, and pharmacotherapy significantly alter the intestinal microenvironment, thus disrupting the gut microbiota composition in HD patients. The gut microbiota may influence HD-related complications, including cardiovascular disease (CVD), infections, anemia, and malnutrition, through mechanisms such as bacterial translocation, immune regulation, and the production of gut microbial metabolites, thereby affecting both the quality of life and the prognosis of patients. This review focuses on alterations in the gut microbiota and its metabolites in HD patients. Additionally, understanding the impact of the gut microbiota on the complications of HD could provide insights into the development of novel treatment strategies to prevent or alleviate complications in HD patients.

The interaction between dietary nitrates/nitrites intake and gut microbial metabolites on metabolic syndrome: a cross-sectional study

Background

Metabolic syndrome (MetS) prevalence has increased globally.The evidence shows thatdiet and gut microbial metabolites includingtrimethylamine N-oxide (TMAO) and kynurenine (KYN) play an important role in developing MetS. However, there is a lack of evidence on associations between between diet and these metabolites. This study aimed to investigate the interaction between dietary nitrate/nitrite and gut microbial metabolites (TMAO, KYN) on MetS and its components.

Methods

This cross-sectional study included 250 adults aged 20-50 years. Dietary intake was assessed using food frequency questionnaires (FFQ), and serum TMAO and KYN levels were measured. MetS was defined usingthe National Cholesterol Education Program Adult Treatment Panel (NCEP ATP III) criteria.

Result

The ATPIII index revealed an 11% prevalence of metabolic syndrome among the study participants. After adjusting for confounders, significant positive interactions were found: High animal-source nitrate intake and high TMAO levels with elevated triglycerides (TG) (p interaction = 0.07) and abdominal obesity (p interaction = 0.08). High animal-source nitrate intake and high KYN levels with increased TG (p interaction = 0.01) and decreased high-density lipoprotein cholesterol (HDL) (p interaction = 0.01).Individuals with high animal-source nitrite intake and high TMAO levels showed increased risk of hypertriglyceridemia (OR: 1.57, 95%CI: 0.35-2.87, p = 0.05), hypertension (OR: 1.53, 95%CI: 0.33-2.58, p = 0.06), and lower HDL (OR: 1.96, 95%CI: 0.42-2.03, p = 0.04). Similarly, high animal-source nitrite intake with high KYN levels showed lower HDL (OR: 2.44, 95%CI: 1.92-3.89, p = 0.07) and increased risk of hypertension (OR: 2.17,95%CI: 1.69-3.40, p = 0.05). Conversely, Negative interactions were found between high plant-source nitrate/nitrite intake with high KYN and TMAO levels on MetS and some components.

Conclusion

There is an interaction between dietary nitrate/nitrite source (animal vs. plant) and gut microbial metabolites (TMAO and KYN) on the risk of of MetS and its components. These findings highlight the importance of considering diet, gut microbiome metabolites, and their interactions in MetS risk assessment.

Trimethylamine-N-oxide and 5-year mortality: the role of gut microbiota-generated metabolite from the CORE-Thailand cohort

The gut microbiota metabolite trimethylamine-N-oxide (TMAO)-derived from dietary phosphatidylcholine-is mechanistically linked to cardiovascular disease (CVD) and increased cardiovascular risk. This study examined the relationship between fasting plasma TMAO levels and 5-year all-cause mortality in a cohort of patients at high risk of cardiovascular events (CORE-Thailand Registry). Of the 134 patients, 123 (92%) had established cardiovascular disease, and 11 (8%) had multiple risk factors. Fasting plasma TMAO levels were measured using nuclear magnetic resonance spectroscopy. Within this prospective cohort study, the median TMAO was 3.81 μM [interquartile range (IQR) 2.89-5.50 μM], with a mean age of 65 ± 11 years; 61% were men, and 39.6% had type II diabetes. Among 134 patients, 65 (49%) were identified as the high-TMAO group (≥ 3.8 μM), and 69 (51%) were identified as the low-TMAO group (< 3.8 μM). After a median follow-up of 58.8 months, the high-TMAO group was associated with a 2.88-fold increased mortality risk. Following adjustment for traditional risk factors, high-sensitivity cardiac troponin-T, estimated glomerular filtration rate, angiotensin-converting enzyme (ACEI), or angiotensin-receptor blocker (ARB) use, the high-TMAO group remained predictive of 5-year all-cause mortality risk (the high-TMAO vs. the low-TMAO group, adjusted hazard ratio 2.73, 95% CI 1.13-6.54; P = 0.025). Among Thai patients at high risk of cardiovascular events, increased plasma TMAO levels portended greater long-term mortality risk.

Semi-supervised meta-learning elucidates understudied molecular interactions

Many biological problems are understudied due to experimental limitations and human biases. Although deep learning is promising in accelerating scientific discovery, its power compromises when applied to problems with scarcely labeled data and data distribution shifts. We develop a deep learning framework-Meta Model Agnostic Pseudo Label Learning (MMAPLE)-to address these challenges by effectively exploring out-of-distribution (OOD) unlabeled data when conventional transfer learning fails. The uniqueness of MMAPLE is to integrate the concept of meta-learning, transfer learning and semi-supervised learning into a unified framework. The power of MMAPLE is demonstrated in three applications in an OOD setting where chemicals or proteins in unseen data are dramatically different from those in training data: predicting drug-target interactions, hidden human metabolite-enzyme interactions, and understudied interspecies microbiome metabolite-human receptor interactions. MMAPLE achieves 11% to 242% improvement in the prediction-recall on multiple OOD benchmarks over various base models. Using MMAPLE, we reveal novel interspecies metabolite-protein interactions that are validated by activity assays and fill in missing links in microbiome-human interactions. MMAPLE is a general framework to explore previously unrecognized biological domains beyond the reach of present experimental and computational techniques.

Consumption of different types of meat and the risk of chronic limb-threatening ischemia: the Singapore Chinese Health Study

BACKGROUND

Although red meat consumption has been associated with risk of atherosclerotic coronary artery disease and stroke, no prospective study has examined this with the risk of chronic limb-threatening ischemia (CLTI).

METHODS

In a prospective study of 63,257 Chinese in Singapore, who were aged 45-74 years old at recruitment, diet was assessed via a validated semi-quantitative food frequency questionnaire. Incident CLTI cases were ascertained via linkage with nationwide hospital records for lower extremity amputation or angioplasty for peripheral arterial disease. Multivariable Cox models were used to examine associations between quartiles of meat intake and CLTI risk.

RESULTS

After a mean follow-up of 18.8 years, there were 1069 cases of CLTI. Higher intake of red meat intake was associated with increased risk of CLTI in a stepwise manner. Comparing extreme quartiles of red meat intake, the hazard ratio (HR) for the association with CLTI risk was 1.24 [95% confidence interval (CI) = 1.03-1.49; P-trend = 0.02]. In stratified analysis, red meat intake had a stronger association with CLTI risk among those without diabetes [HR (95% CI) comparing extreme quartiles = 1.41 (1.10-1.80); P-trend = 0.03] than among those with diabetes at baseline [HR (95% CI) comparing extreme quartiles = 1.04 (0.79-1.38); P-trend = 0.05] (P-interaction = 0.03). Otherwise, the associations were not different by sex, BMI, smoking status, hypertension, alcohol consumption, or history of cardiovascular diseases. Using a theoretical model in substitution analysis that substituted three servings per week of red meat with poultry or fish/shellfish, the relative risk of CLTI was reduced by 13-14%.

CONCLUSIONS

Consumption of red meat was associated with higher CLTI risk in this Asian cohort. Substituting red meat with poultry or fish/shellfish may reduce this risk.

Treatment with Gac Fruit Extract and Probiotics Reduces Serum Trimethylamine N-Oxide in Chronic Kidney Disease Rats

Chronic kidney disease (CKD) affects more than 850 million people worldwide, contributing to morbidity and mortality, particularly through cardiovascular disease (CVD). The altered composition in CKD patients leads to increased production and absorption of uremic toxins such as trimethylamine (TMA) and its oxidized form, trimethylamine N-oxide (TMAO), which are associated with cardiovascular risks. This study investigated the potential of supplementary interventions with high-carotenoid-content gac fruit extract and probiotics to mitigate serum TMAO by modulating the gut microbiota. We conducted an animal study involving 48 male Wistar rats, divided into six groups: the control, CKD control, and four treatment groups receiving gac fruit extract, carotenoid extract, or combinations with Ligilactobacillus salivarius and Lactobacillus crispatus and Lactobacillus casei as a standard probiotic. CKD was induced in rats using cisplatin and they were supplemented with choline to enhance TMA production. The measures included serum creatinine, TMAO levels, gut microbiota composition, and the expression of fecal TMA lyase and intestinal zonula occluden-1 (ZO-1). CKD rats showed increased TMA production and elevated serum levels of TMAO. Treatment with gac fruit extract and selective probiotics significantly altered the composition of the gut microbiota by decreasing Actinobacteriota abundance and increasing the abundance of Bacteroides. This combination effectively promoted ZO-1 expression, reduced fecal TMA lyase, and subsequently lowered serum TMAO levels, demonstrating the therapeutic potential of these interventions. Our results highlight the benefits of gac fruit extract combined with probiotics for the effective reduction in serum TMAO levels in rats with CKD, supporting the further exploration of dietary and microbial interventions to improve outcomes in patients with CKD.

Association of Serum Trimethylamine-N-Oxide Concentration from Childhood to Early Adulthood with Age and Sex

BACKGROUND

Primary prevention is the cornerstone of cardiometabolic health. In the randomized, controlled Special Turku Coronary Risk Factor Intervention Project (STRIP), dietary counseling intervention was given to children from infancy to 20 years of age and a follow-up was completed at age 26 years. We investigated the associations of age, sex, gut microbiome, and dietary intervention with the gut metabolite and the cardiac biomarker trimethylamine-N-oxide (TMAO).

METHODS

Overall, 592 healthy participants (females 46%) from STRIP were investigated. Compared to the control group, the intervention group had received dietary counseling between ages 7 months and 20 years focused on low intakes of saturated fat and cholesterol and the promotion of fruit, vegetable, and whole-grain consumption. TMAO serum concentrations were measured by a liquid chromatography-tandem mass spectrometry method at ages 11, 13, 15, 17, 19, and 26 years. Microbiome composition was assessed using 16S rRNA gene sequencing at 26 years of age.

RESULTS

TMAO concentrations increased from age 11 to 26 years in both sexes. At all measurement time points, males showed significantly higher serum TMAO concentrations compared to females, but concentrations were similar between the intervention and control groups. A direct association between TMAO concentrations and reported fiber intake was found in females. Gut microbiome analysis did not reveal associations with TMAO.

CONCLUSIONS

TMAO concentration increased from childhood to early adulthood but was not affected by the given dietary intervention. In females, TMAO concentrations could be directly associated with higher fiber intake suggesting sex-specific differences in TMAO metabolism.

eIF6 deficiency regulates gut microbiota, decreases systemic inflammation, and alleviates atherosclerosis

Altered composition of the gut microbiota affects immunity and metabolism. This study previously found that eIF6 gene knockdown changes the composition of the intestinal flora in the eIF6 gene knockdown mouse model. Lactobacillus acidophilus is significantly increased in the model. This study was designed to investigate the role of L. acidophilus in the pathogenesis of atherosclerosis. Transcriptomic data from 117 patients with coronary artery disease (CAD) and 79 healthy individuals were obtained. ApoE-/- and ApoE-/-/eIF6+/- mice on normal chow diet or a high-fat diet were treated for 16 weeks; eIF6 deficiency was evaluated atherosclerosis. ApoE-/- mice on normal chow diet or a high-fat diet were treated with L. acidophilus by daily oral gavage for 16 weeks. Moreover, one group was treated with lipopolysaccharide at 12 weeks. The levels of eIF6, RNASE3, and RSAD2 were notably higher in the patients with CAD than in the healthy individuals. eIF6 deficiency altered the composition of gut microbiota. eIF6 deficiency reduced the atherosclerotic lesion formation in ApoE-/-/eIF6+/- mice compared with the ApoE-/- mice. The microbial sequencing and metabolomics analysis demonstrated some beneficial bacterial (L. acidophilus, Ileibacterium, and Bifidobacterium) and metabolic levels significantly had deference in ApoE-/-/eIF6+/- mice compared with the ApoE-/- mice. Correlational studies indicated that L. acidophilus had close correlations with low-density lipoprotein cholesterol, lesion area, and necrotic area. L. acidophilus inhibited high-fat diet-induced inflammation and atherosclerotic lesion, increasing the expression of tight junction proteins (ZO-1 and claudin-1) and reducing the gut permeability. However, lipopolysaccharide reversed the protective effect of L. acidophilus against atherosclerosis. eIF6 deficiency protected against atherosclerosis by regulating the composition of gut microbiota and metabolites. L. acidophilus attenuated atherosclerotic lesions by reducing inflammation and increasing gut permeability.IMPORTANCEeIF6 deficiency modulates the gut microbiota and multiple metabolites in atherosclerotic ApoE-/- mice. L. acidophilus was reduced in the gut of atherosclerotic ApoE-/- mice, but administration of Lactobacillus acidophilus reversed intestinal barrier dysfunction and vascular inflammation. Our findings suggest that targeting individual species is a beneficial therapeutic strategy to prevent inflammation and atherosclerosis.

We Are What, When, And How We Eat: The Evolutionary Impact of Dietary Shifts on Physical and Cognitive Development, Health, and Disease

"We are what, when, and how we eat": the evolution of human dietary habits mirrors the evolution of humans themselves. Key developments in human history, such as the advent of stone tool technology, the shift to a meat-based diet, control of fire, advancements in cooking and fermentation techniques, and the domestication of plants and animals, have significantly influenced human anatomical, physiological, social, cognitive, and behavioral changes. Advancements in scientific methods, such as the analysis of microfossils like starch granules, plant-derived phytoliths, and coprolites, have yielded unprecedented insights into past diets. Nonetheless, the isolation of ancient food matrices remains analytically challenging. Future technological breakthroughs and a more comprehensive integration of paleogenomics, paleoproteomics, paleoglycomics, and paleometabolomics will enable a more nuanced understanding of early human ancestors' diets, which holds the potential to guide contemporary dietary recommendations and tackle modern health challenges, with far-reaching implications for human well-being, and ecological impact on the planet.

The Gut Microbiota and Diabetes: Research, Translation, and Clinical Applications-2023 Diabetes, Diabetes Care, and Diabetologia Expert Forum

This article summarizes the state of the science on the role of the gut microbiota (GM) in diabetes from a recent international expert forum organized by Diabetes, Diabetes Care, and Diabetologia, which was held at the European Association for the Study of Diabetes 2023 Annual Meeting in Hamburg, Germany. Forum participants included clinicians and basic scientists who are leading investigators in the field of the intestinal microbiome and metabolism. Their conclusions were as follows: 1) the GM may be involved in the pathophysiology of type 2 diabetes, as microbially produced metabolites associate both positively and negatively with the disease, and mechanistic links of GM functions (e.g., genes for butyrate production) with glucose metabolism have recently emerged through the use of Mendelian randomization in humans; 2) the highly individualized nature of the GM poses a major research obstacle, and large cohorts and a deep-sequencing metagenomic approach are required for robust assessments of associations and causation; 3) because single-time point sampling misses intraindividual GM dynamics, future studies with repeated measures within individuals are needed; and 4) much future research will be required to determine the applicability of this expanding knowledge to diabetes diagnosis and treatment, and novel technologies and improved computational tools will be important to achieve this goal.

Metabolomics Characterization of Disease Markers in Diabetes and Its Associated Pathologies

With the change in lifestyle of people, there has been a considerable increase in diabetes, which brings with it certain follow-up pathological conditions, which lead to a substantial medical burden. Identifying biomarkers that aid in screening, diagnosis, and prognosis of diabetes and its associated pathologies would help better patient management and facilitate a personalized treatment approach for prevention and treatment. With the advancement in techniques and technologies, metabolomics has emerged as an omics approach capable of large-scale high throughput data analysis and identifying and quantifying metabolites that provide an insight into the underlying mechanism of the disease and its progression. Diabetes and metabolomics keywords were searched in correspondence with the assigned keywords, including kidney, cardiovascular diseases and critical illness from PubMed and Scopus, from its inception to Dec 2023. The relevant studies from this search were extracted and included in the study. This review is focused on the biomarkers identified in diabetes, diabetic kidney disease, diabetes-related development of CVD, and its role in critical illness.

Mendelian randomization study to assess causality between diet and phenotype of aging

BACKGROUND AND OBJECTIVES

Observational research findings have demonstrated correlations between diet and the process of aging. Nevertheless, there remains uncertainty regarding possible disruption caused by confounding variables. To elucidate the connections between diet and aging, we employed the Mendelian randomization analysis.

METHODS AND STUDY DESIGN

The exposure factor was the daily diet, whereas accelerated aging was measured through telomere length, facial aging (FA), frailty index (FI), and senescence-associated secretory phenotypes (SASPs), representing the outcome factors. The primary analysis employed IVW analysis, with additional MR-Egger and Weighted Median analyses conducted to assess the reliability of the findings. Furthermore, we analyzed the heterogeneity and pleiotropy of the results.

RESULTS

The results revealed that the consumption of salad/raw vegetables and oily fish exhibited a negative correlation with FA, whereas coffee intake showed a positive correlation with FA. On the other hand, the intake of cheese, oily fish, dried fruit, and cereal showed negative associations with FI. Additionally, coffee, alcohol, and pork intake were positively associated with FI. Lastly, the intake of bread exhibited a positively correlated with SASPs, while the intake of cheese and coffee showed a negative correlation with SASPs.

CONCLUSIONS

Our study revealed that the consumption of cheese, vegetables, oily fish, dried fruit, bread, coffee, and alcohol was associated with the aging process. Interestingly, our findings suggest that coffee intake may accelerate aging, whereas intake of oily fish may delay the aging process. However, it is important to note that further well-designed prospective studies are required to validate our findings in the future.

Effects of resveratrol on changes in trimethylamine-N-oxide and circulating cardiovascular factors following exercise training among older adults

PURPOSE

Trimethylamine-N-oxide (TMAO) is a gut-derived metabolite associated with cardiovascular disease (CVD). In preclinical and observational studies, resveratrol and exercise training have been suggested as potential strategies to reduce the systemic levels of TMAO. However, evidence from experimental studies in humans remains unknown. This project examined the dose-dependent effects of a combined resveratrol intervention with exercise training on circulating TMAO and other related metabolite signatures in older adults with high CVD risk.

METHODS

Forty-one older adults [mean (±SD) age of 72.1 (6.8) years] participated in a 12-week supervised center-based, multi-component exercise training intervention [2×/week; 80 min/session] and were randomized to one of two resveratrol dosages [Low: 500 vs. High:1000 mg/day] or a cellulose-based placebo. Serum/plasma were collected at baseline and post-intervention and evaluated for TMAO and associated analytes.

RESULTS

After the 12-week intervention, TMAO concentration increased over time, regardless of treatment [mean (±SD) Placebo: 11262 (±3970); Low:13252 (±1193); High: 12661(±3359) AUC; p = 0.04]. Each resveratrol dose produced different changes in metabolite signatures. Low dose resveratrol upregulated metabolites associated with bile acids biosynthesis (i.e., glycochenodeoxycholic acid, glycoursodeoxycholic acid, and glycocholic acid). High dose resveratrol modulated metabolites enriched for glycolysis, and pyruvate, propanoate, β-alanine, and tryptophan metabolism. Different communities tightly correlated to TMAO and resveratrol metabolites were associated with the lipid and vascular inflammatory clinical markers [|r| > 0.4, p < 0.05].

CONCLUSION

These findings suggest a distinct dose-dependent adaptation response to resveratrol supplementation on circulating metabolite signatures but not on TMAO among high-risk CVD older adults when combined with an exercise training intervention.

The metabolic and endocrine impact of diet-derived gut microbiota metabolites on ageing and longevity

Gut dysbiosis has been recently recognized as a hallmark of ageing. At this stage of life, gut microbiota becomes depleted from bacteria involved in the production of short-chain fatty acids (SCFA), indole and its derivative indole-3-propionic acid (IPA), metabolites shown to improve host glycemic control as well as insulin sensitivity and secretion. Moreover, gut microbiota becomes enriched in pathobiont bacteria involved in the production of imidazole propionate, phenols and trimethylamine, metabolites that promote host insulin resistance and atherosclerosis. The magnitude of these changes is much more pronounced in unhealthy than in healthy ageing. On the other hand, a distinct gut microbiota signature is displayed during longevity, the most prominent being an enrichment in both SCFA and IPA bacterial producers. This short Review discusses, in an innovative and integrative way, cutting-edge research on the composition of gut microorganisms and profile of metabolites secreted by them, that are associated with a healthy and unhealthy ageing pattern and with longevity. A detailed description of the positive or detrimental metabolic effects, in the ageing host, of diet-derived gut microbial metabolites is provided. Finally, microbiota-targeted interventions that counteract gut dysbiosis associated with ageing, are briefly outlined.

Microbiome miracles and their pioneering advances and future frontiers in cardiovascular disease

Cardiovascular diseases (CVDs) represent a significant global health challenge, underscoring the need for innovative approaches to prevention and treatment. Recent years have seen a surge in interest in unraveling the complex relationship between the gut microbiome and cardiovascular health. This article delves into current research on the composition, diversity, and impact of the gut microbiome on CVD development. Recent advancements have elucidated the profound influence of the gut microbiome on disease progression, particularly through key mediators like Trimethylamine-N-oxide (TMAO) and other microbial metabolites. Understanding these mechanisms reveals promising therapeutic targets, including interventions aimed at modulating the gut microbiome's interaction with the immune system and its contribution to endothelial dysfunction. Harnessing this understanding, personalized medicine strategies tailored to individuals' gut microbiome profiles offer innovative avenues for reducing cardiovascular risk. As research in this field continues to evolve, there is vast potential for transformative advancements in cardiovascular medicine, paving the way for precision prevention and treatment strategies to address this global health challenge.

Microbiota alterations associated with vascular diseases: postbiotics as a next-generation magic bullet for gut-vascular axis

The intestinal microbiota represents a key element in maintaining the homeostasis and health conditions of the host. Vascular pathologies and other risk factors such as aging have been recently associated with dysbiosis. The qualitative and quantitative alteration of the intestinal microbiota hinders correct metabolic homeostasis, causing structural and functional changes of the intestinal wall itself. Impairment of the intestinal microbiota, combined with the reduction of the barrier function, worsen the pathological scenarios of peripheral tissues over time, including the vascular one. Several experimental evidence, collected in this review, describes in detail the changes of the intestinal microbiota in dysbiosis associated with vascular alterations, such as atherosclerosis, hypertension, and endothelial dysfunction, the resulting metabolic disorders and how these can impact on vascular health. In this context, the gut-vascular axis is considered, for the first time, as a merged unit involved in the development and progression of vascular pathologies and as a promising target. Current approaches for the management of dysbiosis such as probiotics, prebiotics and dietary modifications act mainly on the intestinal district. Postbiotics, described as preparation of inanimate microorganisms and/or their components that confers health benefits on the host, represent an innovative strategy for a dual management of intestinal dysbiosis and vascular pathologies. In this context, this review has the further purpose of defining the positive effects of the supplementation of bacterial strains metabolites (short‑chain fatty acids, exopolysaccharides, lipoteichoic acids, gallic acid, and protocatechuic acid) restoring intestinal homeostasis and acting directly on the vascular district through the gut-vascular axis.

The gut microbiota and diabetes: research, translation, and clinical applications - 2023 Diabetes, Diabetes Care, and Diabetologia Expert Forum

This article summarises the state of the science on the role of the gut microbiota (GM) in diabetes from a recent international expert forum organised by Diabetes, Diabetes Care, and Diabetologia, which was held at the European Association for the Study of Diabetes 2023 Annual Meeting in Hamburg, Germany. Forum participants included clinicians and basic scientists who are leading investigators in the field of the intestinal microbiome and metabolism. Their conclusions were as follows: (1) the GM may be involved in the pathophysiology of type 2 diabetes, as microbially produced metabolites associate both positively and negatively with the disease, and mechanistic links of GM functions (e.g. genes for butyrate production) with glucose metabolism have recently emerged through the use of Mendelian randomisation in humans; (2) the highly individualised nature of the GM poses a major research obstacle, and large cohorts and a deep-sequencing metagenomic approach are required for robust assessments of associations and causation; (3) because single time point sampling misses intraindividual GM dynamics, future studies with repeated measures within individuals are needed; and (4) much future research will be required to determine the applicability of this expanding knowledge to diabetes diagnosis and treatment, and novel technologies and improved computational tools will be important to achieve this goal.

Role of L-carnitine in Cardiovascular Health: Literature Review

Cardiovascular diseases (CVDs) remain the leading cause of morbidity and mortality worldwide. Secondary preventive measures, like anti-platelet medications, B-blockers, and angiotensin-converting enzyme (ACE) inhibitors, have been found to dramatically lower the risk of cardiovascular disease. However, prolonged usage of these drugs has been linked to multiple adverse impacts. Hence, finding more efficient treatments, especially dietary strategies for long-term use in daily life, is advantageous for primary prevention and treatment. L-carnitine, a naturally occurring amino acid derivative normally synthesized in the liver and kidney, is believed to have a considerable influence on cardiovascular health. L-carnitine can enhance both contractile performance and structural integrity of the cardiac muscle by maintaining efficient energy production and reducing oxidative stress. This literature review aims to address several pressing questions regarding the role of L-carnitine in cardiovascular health: what are the physiological functions of L-carnitine, particularly in relation to cardiovascular health; how effective and safe is L-carnitine supplementation in the management of various cardiovascular diseases, primarily ischemic heart disease, heart failure, and peripheral vascular disease; what are the underlying mechanisms through which L-carnitine exerts its cardioprotective effects; what controversies exist in the current research; and finally, what should be the future directions? Through this comprehensive analysis, the review aims to enrich our understanding of L-carnitine's role in cardiovascular health, providing a robust foundation for future academic and clinical endeavors. PubMed, Embase, and Google Scholar have been used to search the following keywords: L-carnitine, cardiovascular health, mitochondrial function, and L-carnitine side effects. Then, using the existing search engine formats, some keyword combinations were used to find the related articles included and every possibility, including using every first keyword combination with another keyword, using every keyword in every place at each given box, etc. Around 308 articles were reviewed using this process, including systemic reviews, meta-analysis studies, randomized controlled trials, and literature review articles. In the end, after leaving the pure articles related to the topic as 35 articles, which are attached below with direct citation, the majority of them were very fresh articles, as recent as 2010, and back words, except just one paper related to the impact of L-carnitine post-myocardial infarction, as its data provided us with a positive and promising impact of L-carnitine in this field. L‑carnitine seems to have a pivotal role in cardiovascular health due to its energy metabolism, anti-oxidative stress, and endothelial role. The safety and effectiveness of L-carnitine administration remain an issue for scientific investigation. One of the major concerns is that the intestinal metabolism of L-carnitine generates trimethylamine-N-oxide (TMAO), a compound that has been linked with faster atherosclerosis progression.

The Gut Microbiota and Diabetes: Research, Translation, and Clinical Applications-2023 Diabetes, Diabetes Care, and Diabetologia Expert Forum

This article summarizes the state of the science on the role of the gut microbiota (GM) in diabetes from a recent international expert forum organized by Diabetes, Diabetes Care, and Diabetologia, which was held at the European Association for the Study of Diabetes 2023 Annual Meeting in Hamburg, Germany. Forum participants included clinicians and basic scientists who are leading investigators in the field of the intestinal microbiome and metabolism. Their conclusions were as follows: 1) the GM may be involved in the pathophysiology of type 2 diabetes, as microbially produced metabolites associate both positively and negatively with the disease, and mechanistic links of GM functions (e.g., genes for butyrate production) with glucose metabolism have recently emerged through the use of Mendelian randomization in humans; 2) the highly individualized nature of the GM poses a major research obstacle, and large cohorts and a deep-sequencing metagenomic approach are required for robust assessments of associations and causation; 3) because single-time point sampling misses intraindividual GM dynamics, future studies with repeated measures within individuals are needed; and 4) much future research will be required to determine the applicability of this expanding knowledge to diabetes diagnosis and treatment, and novel technologies and improved computational tools will be important to achieve this goal.

The gut microbiome and serum metabolome are altered and interrelated in patients with intracranial atherosclerotic stenosis

OBJECTIVES

To evaluate the relationship among the gut microbiome, serum metabolites and the Intracranial atherosclerosis stenosis.

MATERIALS AND METHODS

Integrated analysis of 16S rDNA sequencing of fecal samples and untargeted serum metabolomics was applied to identify alterations in the gut microbiome and serum metabolome in 29 Intracranial atherosclerosis stenosis patients and 29 healthy control individuals.

RESULTS

Compared to healthy control individuals, the abundances of forty-five genera and one hundred seventy-seven metabolites were significantly altered in Intracranial atherosclerosis stenosis patients. At the species level, the Intracranial atherosclerosis stenosis group exhibited higher abundances of Bacteroidetes and lower abundances of Megaphaera and Muribacoccaceae. Microbial functional prediction analysis revealed enhanced activity of bacterial chemotaxis and oxidative phosphorylation within the Intracranial atherosclerosis stenosis group. In terms of metabolomic findings, the levels of dulcitol were significantly increased in the Intracranial atherosclerosis stenosis group. The levels of specific metabolites within the phosphatidylcholine and lysophosphatidylcholine families, such as PC (14:0e/24:4) and LPC 20:5, were increased, while the levels of certain other specific metabolites were decreased. Dysregulation of certain pathways, such as unsaturated fatty acid metabolism, arginine and proline metabolism may be involved in the development of Intracranial atherosclerosis stenosis. Correlation analysis of the gut microbiome and metabolites revealed a positive correlation between Bacteroides and multiple metabolites, such as Acar 12:3 and PC (8:0/22:6).

CONCLUSIONS

Our analysis revealed that Bacteroides is a key bacterial genus in gut dysbiosis and may be related to the development of Intracranial atherosclerosis stenosis.

Novel Targets and Strategies Addressing Residual Cardiovascular Risk in Post-acute Coronary Syndromes Patients

Despite the advancement in secondary cardiovascular prevention strategies for post-acute coronary syndrome (ACS) patients, the development of new drugs addressing dyslipidemia and the personalization of dual antiplatelet therapies (DAPT), these patients continue to suffer a significant incidence of recurrent ischemic events. Therefore, novel targets that can be tackled to reduce cardiovascular risk are needed to improve the outcome of this very high-risk population. The role of chronic inflammation and inflammasome in the development and progression of atherosclerosis has been broadly investigated in patients with established coronary artery disease (CAD) and recent randomized trials have highlighted the possibility to manage these targets with specific drugs such as colchicine and monocolonal antibodies with a significant improvement of cardiovascular outcomes in post-ACS patients. Lipoprotein(a) [Lp(a)] is the most promising non-traditional risk factor and has shown to predict worse outcome in post-ACS patients. Lowering Lp(a) through PCSK9 inhibitors and specific targeted therapies has shown positive results in reducing adverse cardiovascular events in patients with established CAD. The effect of microbiome and its alteration in gut dysbiosis seems to actively participate in residual cardiovascular risk of CAD patients; however, the risk-modifying effect of targeted-microbiome therapies hasn't been yet investigated in large population-based studies. Long-term outcome of post-ACS patients is a complex puzzle of multiple factors. In this minireview, we summarize the emerging risk factors that may interplay in the residual risk of post-ACS patients and their possible prognostic and therapeutic implications.

Gut microbiota alterations in renal transplant recipients and the risk of urinary tract infection and delayed graft function: A preliminary prospective study

BACKGROUND

The implication of gut microbiota in the gut-kidney axis affects the pathophysiology of chronic kidney disease (CKD). Gut microbiota composition changes during CKD. We aimed to determine the relative frequency of important gut microbiota members in end-stage renal disease (ERSD) patients before and after renal transplantation compared to healthy subjects.

METHODS

Fifteen kidney transplant patients and 10 healthy subjects were recruited in this case-control prospective study. Fecal samples were taken sequentially from all patients before kidney transplantation, 1 week, and 1 month after it. The relative frequency of Lactobacillus spp., Bifidobacterium spp., Akkermansia muciniphila, Bacteroides fragilis, Escherichia coli, and Faecalibacterium pruasnitzii were determined through quantitative PCR. The obtained data was statistically analyzed by Stata software (Stata Corporation, USA).

RESULTS

The mean log number of all bacteria was significantly higher in healthy individuals than kidney transplant recipients (p < 0.001) except for Lactobacillus where the mean levels were almost identical in the two groups (p = 0.67). Moreover, 20% (3) of patients developed a urinary tract infection. Besides, 2 (13.33%) patients were diagnosed with delayed graft function. There were no statistically significant differences regarding changing trends in bacteria log number of Akkermansia muciniphila (p = 0.12), Bacteroid fragilis (p = 0.75), Bifidobacterium (p = 0.99), Escherichia coli (p = 0.5), Faecalibacterium (p = 0.98), and Lactobacilli (p = 0.93) between patients with and without delayed graft function (DGF).

CONCLUSION

Gut microbiota composition in patients with ESRD was significantly different from those without it. However, the microbiota profile did not significantly differ in patients with and without DGF.

Deficiency of flavin-containing monooxygenase 3 protects kidney function after ischemia-reperfusion in mice

The kidney is vulnerable to ischemia and reperfusion (I/R) injury that can be fatal after major surgery. Currently, there are no effective treatments for I/R-induced kidney injury. Trimethylamine N-oxide (TMAO) is a gut-derived metabolite linked to many diseases, but its role in I/R-induced kidney injury remains unclear. Here, our clinical data reveals an association between preoperative systemic TMAO levels and postoperative kidney injury in patients after post-cardiopulmonary bypass surgery. By genetic deletion of TMAO-producing enzyme flavin-containing monooxygenase 3 (FMO3) and dietary supplementation of choline to modulate TMAO levels, we found that TMAO aggravated acute kidney injury through the triggering of endoplasmic reticulum (ER) stress and worsened subsequent renal fibrosis through TGFβ/Smad signaling activation. Together, our study underscores the negative role of TMAO in I/R-induced kidney injury and highlights the therapeutic potential through the modulation of TMAO levels by targeting FMO3, thereby mitigating acute kidney injury and preventing subsequent renal fibrosis.

Gut microbial metabolites: Shaping future diagnosis and treatment against gastrointestinal cancer

Gastrointestinal cancer is a worldwide health challenge due to its dramatically increasing prevalence and as a leading cause of cancer-related mortality. Increasing evidence has illustrated the vital role of gut microbes-derived metabolites in gastrointestinal cancer progression and treatment. Microbial metabolites are produced by the gut microbiota that utilizes both extrinsic dietary components and intrinsic host-generated compounds. Meanwhile, certain categories of metabolites such as short-chain fatty acids, bile acids, tryptophan, and indole derivatives, are linked to gastrointestinal malignancy. In this review, the major classes of microbial metabolites and their impacts on various gastrointestinal cancers including colorectal cancer, gastric cancer, and hepatocellular carcinoma, have been introduced. The application of microbial metabolites as predictive biomarkers for early diagnosis and prognosis of gastrointestinal cancer has also been explored. In addition, therapeutic potential of strategies that target microbial metabolites against gastrointestinal cancer is further evaluated.

Circulating Gut Microbe-Derived Metabolites Are Associated with Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the third leading cause of cancer death worldwide. The gut microbiome has been implicated in outcomes for HCC, and gut microbe-derived products may serve as potential non-invasive indices for early HCC detection. This study evaluated differences in plasma concentrations of gut microbiota-derived metabolites.

METHODS

Forty-one patients with HCC and 96 healthy controls were enrolled from surgical clinics at the Cleveland Clinic from 2016 to 2020. Gut microbiota-derived circulating metabolites detectable in plasma were compared between patients with HCC and healthy controls. Hierarchical clustering was performed for generating heatmaps based on circulating metabolite concentrations using ClustVis, with Euclidean and Ward settings and significant differences between metabolite concentrations were tested using a binary logistic regression model.

RESULTS

In patients with HCC, 25 (61%) had histologically confirmed cirrhosis. Trimethylamine (TMA)-related metabolites were found at higher concentrations in those with HCC, including choline (p < 0.001), betaine (p < 0.001), carnitine (p = 0.007), TMA (p < 0.001) and trimethylamine N-oxide (TMAO, p < 0.001). Notably, concentrations of P-cresol glucuronide (p < 0.001), indole-lactic acid (p = 0.038), 5-hydroxyindoleacetic acid (p < 0.0001) and 4-hydroxyphenyllactic acid (p < 0.001) were also increased in those with HCC compared to healthy controls. Hierarchical clustering of the metabolite panel separated patients based on the presence of HCC (p < 0.001), but was not able to distinguish between patients with HCC based on the presence of cirrhosis (p = 0.42).

CONCLUSIONS

Gut microbiota-derived metabolites were differentially abundant in patients with HCC versus healthy controls. The observed perturbations of the TMAO pathway in HCC seem particularly promising as a target of future research and may have both diagnostic and therapeutic implications.

Interactions between Gut Microbiota and Natural Bioactive Polysaccharides in Metabolic Diseases: Review

The gut microbiota constitutes a complex ecosystem, comprising trillions of microbes that have co-evolved with their host over hundreds of millions of years. Over the past decade, a growing body of knowledge has underscored the intricate connections among diet, gut microbiota, and human health. Bioactive polysaccharides (BPs) from natural sources like medicinal plants, seaweeds, and fungi have diverse biological functions including antioxidant, immunoregulatory, and metabolic activities. Their effects are closely tied to the gut microbiota, which metabolizes BPs into health-influencing compounds. Understanding how BPs and gut microbiota interact is critical for harnessing their potential health benefits. This review provides an overview of the human gut microbiota, focusing on its role in metabolic diseases like obesity, type II diabetes mellitus, non-alcoholic fatty liver disease, and cardiovascular diseases. It explores the basic characteristics of several BPs and their impact on gut microbiota. Given their significance for human health, we summarize the biological functions of these BPs, particularly in terms of immunoregulatory activities, blood sugar, and hypolipidemic effect, thus providing a valuable reference for understanding the potential benefits of natural BPs in treating metabolic diseases. These properties make BPs promising agents for preventing and treating metabolic diseases. The comprehensive understanding of the mechanisms by which BPs exert their effects through gut microbiota opens new avenues for developing targeted therapies to improve metabolic health.

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.

Broadening horizons: intestinal microbiota as a novel biomarker and potential treatment for hypertensive disorders of pregnancy

Hypertensive disorders of pregnancy (HDP) are severe complications of pregnancy with high morbidity and are a major cause of increased maternal and infant morbidity and mortality. Currently, there is a lack of effective early diagnostic indicators and safe and effective preventive strategies for HDP in clinical practice, except for monitoring maternal blood pressure levels, the degree of proteinuria, organ involvement and fetal conditions. The intestinal microbiota consists of the gut flora and intestinal environment, which is the largest microecosystem of the human body and participates in material and energy metabolism, gene expression regulation, immunity regulation, and other functions. During pregnancy, due to changes in hormone levels and altered immune function, the intestinal microecological balance is affected, triggering HDP. A dysregulated intestinal microenvironment influences the composition and distribution of the gut flora and changes the intestinal barrier, driving beneficial or harmful bacterial metabolites and inflammatory responses to participate in the development of HDP and promote its malignant development. When the gut flora is dysbiotic and affects blood pressure, supplementation with probiotics and dietary fiber can be used to intervene. In this review, the interaction between the intestinal microbiota and HDP was investigated to explore the feasibility of the gut flora as a novel biomarker of HDP and to provide a new strategy and basis for the prevention and treatment of clinical HDP.

Interactions between the gut microbiome, associated metabolites and the manifestation and progression of heart failure with preserved ejection fraction in ZSF1 rats

BACKGROUND

Heart failure with preserved ejection fraction (HFpEF) is associated with systemic inflammation, obesity, metabolic syndrome, and gut microbiome changes. Increased trimethylamine-N-oxide (TMAO) levels are predictive for mortality in HFpEF. The TMAO precursor trimethylamine (TMA) is synthesized by the intestinal microbiome, crosses the intestinal barrier and is metabolized to TMAO by hepatic flavin-containing monooxygenases (FMO). The intricate interactions of microbiome alterations and TMAO in relation to HFpEF manifestation and progression are analyzed here.

METHODS

Healthy lean (L-ZSF1, n = 12) and obese ZSF1 rats with HFpEF (O-ZSF1, n = 12) were studied. HFpEF was confirmed by transthoracic echocardiography, invasive hemodynamic measurements, and detection of N-terminal pro-brain natriuretic peptide (NT-proBNP). TMAO, carnitine, symmetric dimethylarginine (SDMA), and amino acids were measured using mass-spectrometry. The intestinal epithelial barrier was analyzed by immunohistochemistry, in-vitro impedance measurements and determination of plasma lipopolysaccharide via ELISA. Hepatic FMO3 quantity was determined by Western blot. The fecal microbiome at the age of 8, 13 and 20 weeks was assessed using 16s rRNA amplicon sequencing.

RESULTS

Increased levels of TMAO (+ 54%), carnitine (+ 46%) and the cardiac stress marker NT-proBNP (+ 25%) as well as a pronounced amino acid imbalance were observed in obese rats with HFpEF. SDMA levels in O-ZSF1 were comparable to L-ZSF1, indicating stable kidney function. Anatomy and zonula occludens protein density in the intestinal epithelium remained unchanged, but both impedance measurements and increased levels of LPS indicated an impaired epithelial barrier function. FMO3 was decreased (- 20%) in the enlarged, but histologically normal livers of O-ZSF1. Alpha diversity, as indicated by the Shannon diversity index, was comparable at 8 weeks of age, but decreased by 13 weeks of age, when HFpEF manifests in O-ZSF1. Bray-Curtis dissimilarity (Beta-Diversity) was shown to be effective in differentiating L-ZSF1 from O-ZSF1 at 20 weeks of age. Members of the microbial families Lactobacillaceae, Ruminococcaceae, Erysipelotrichaceae and Lachnospiraceae were significantly differentially abundant in O-ZSF1 and L-ZSF1 rats.

CONCLUSIONS

In the ZSF1 HFpEF rat model, increased dietary intake is associated with alterations in gut microbiome composition and bacterial metabolites, an impaired intestinal barrier, and changes in pro-inflammatory and health-predictive metabolic profiles. HFpEF as well as its most common comorbidities obesity and metabolic syndrome and the alterations described here evolve in parallel and are likely to be interrelated and mutually reinforcing. Dietary adaption may have a positive impact on all entities.

A metabolome-wide Mendelian randomization study prioritizes causal circulating metabolites for reproductive disorders including primary ovarian insufficiency, polycystic ovary syndrome, and abnormal spermatozoa

BACKGROUND

Accumulating studies have highlighted the significant role of circulating metabolomics in the etiology of reproductive system disorders. However, the causal effects between genetically determined metabolites (GDMs) and reproductive diseases, including primary ovarian insufficiency (POI), polycystic ovary syndrome (PCOS), and abnormal spermatozoa (AS), still await thorough clarification.

METHODS

With the currently most comprehensive genome-wide association studies (GWAS) data of metabolomics, systematic two-sample Mendelian randomization (MR) analyses were conducted to disclose causal associations between 1,091 blood metabolites and 309 metabolite ratios with reproductive disorders. The inverse-variance weighted (IVW) method served as the primary analysis approach, and multiple effective MR methods were employed as complementary analyses including MR-Egger, weighted median, constrained maximum likelihood (cML-MA), contamination mixture method, robust adjusted profile score (MR-RAPS), and debiased inverse-variance weighted method. Heterogeneity and pleiotropy were assessed via MR-Egger intercept and Cochran's Q statistical analysis. Outliers were detected by Radial MR and MR-PRESSO methods. External replication and metabolic pathway analysis were also conducted.

RESULTS

Potential causal associations of 63 GDMs with POI were unearthed, and five metabolites with strong causal links to POI were emphasized. Two metabolic pathways related to the pathogenesis of POI were pinpointed. Suggestive causal effects of 70 GDMs on PCOS were detected, among which 7 metabolites stood out for strong causality with elevated PCOS risk. Four metabolic pathways associated with PCOS mechanisms were recognized. For AS, 64 GDMs as potential predictive biomarkers were identified, particularly highlighting two metabolites for their strong causal connections with AS. Three pathways underneath the AS mechanism were identified. Multiple assessments were conducted to further confirm the reliability and robustness of our causal inferences.

CONCLUSION

By extensively assessing the causal implications of circulating GDMs on reproductive system disorders, our study underscores the intricate and pivotal role of metabolomics in reproductive ill-health, laying a theoretical foundation for clinical strategies from metabolic insights.

The Potential Role of Butyrate in the Pathogenesis and Treatment of Autoimmune Rheumatic Diseases

The gut microbiota is a complex ecosystem of microorganisms residing in the human gastrointestinal tract, playing a crucial role in various biological processes and overall health maintenance. Dysbiosis, an imbalance in the composition and function of the gut microbiota, is linked to systemic autoimmune diseases (SAD). Short-chain fatty acids (SCFAs), especially butyrate, produced by the gut microbiota through the fermentation of dietary fibers, play a significant role in immunomodulation and maintaining intestinal homeostasis. Butyrate is essential for colonocyte energy, anti-inflammatory responses, and maintaining intestinal barrier integrity. Studies show reduced butyrate-producing bacteria in SAD patients, suggesting that increasing butyrate levels could have therapeutic benefits. Butyrate's anti-inflammatory effects and its potential therapeutic role have been studied in rheumatoid arthritis, Sjogren's syndrome, systemic lupus erythematosus, systemic sclerosis, and Behçet's disease. Despite promising in vitro and animal model results, human studies are limited, and the optimal strategies for modulating dysbiosis in SADs remain elusive. This review explores the current evidence on the immunoregulatory role of butyrate and its potential therapeutic effects in SAD.