Two distinct gut microbial pathways contribute to meta-organismal production of phenylacetylglutamine with links to cardiovascular disease

Gut microbial genomes with paired isolates from China illustrate probiotic and cardiometabolic effects

The gut microbiome displays genetic differences among populations, and characterization of the genomic landscape of the gut microbiome in China remains limited. Here, we present the Chinese Gut Microbial Reference (CGMR) set, comprising 101,060 high-quality metagenomic assembled genomes (MAGs) of 3,707 nonredundant species from 3,234 fecal samples across primarily rural Chinese locations, 1,376 live isolates mainly from lactic acid bacteria, and 987 novel species relative to worldwide databases. We observed region-specific coexisting MAGs and MAGs with probiotic and cardiometabolic functionalities. Preliminary mouse experiments suggest a probiotic effect of two Faecalibacillus intestinalis isolates in alleviating constipation, cardiometabolic influences of three Bacteroides fragilis_A isolates in obesity, and isolates from the genera Parabacteroides and Lactobacillus in host lipid metabolism. Our study expands the current microbial genomes with paired isolates and demonstrates potential host effects, contributing to the mechanistic understanding of host-microbe interactions.

Type 3 resistant starch from Canna edulis reduce lipid levels in patients with mild hyperlipidemia through altering gut microbiome: A double- blind randomized controlled trial

Type 3 resistant starch from Canna edulis (Ce-RS3) is an insoluble dietary fiber which could improve blood lipids in animals, but clinically robust evidence is still lacking. We performed a double-blind randomized controlled trial to assess the effects of Ce-RS3 on lipids in mild hyperlipidemia. One hundred and fifteen patients were included followed the recruitment criteria, and were randomly allocated to receive Ce-RS3 or placebo (native starch from Canna edulis) for 12 weeks (20 g/day). In addition to serum lipids, complete blood counts, serum inflammatory factors, antioxidant indexes, and dietary survey, 16 S rRNA sequencing technique was utilized to analyze the gut microbiota alterations. Targeted quantitative metabolomics (TQM) was used to detect metabolite changes. Compared with the placebo, Ce- RS3 significantly decreased levels of total cholesterol, lowdensity lipoprotein cholesterol, and non-high-density lipoprotein cholesterol, and increased the glutathione peroxidase. Based on the 16 S rRNA sequencing, TQM, the correlation analysis, as well as the Kyoto Encyclopedia of Genes (KEGG) and Genomes and Human Metabolome Database (HMDB) analysis, we found that Ce-RS3 could increase the abundances of genera Faecalibacterium and Agathobacter, while reduce the abundances of genera norank_f_Ruminococcaceae and Christensenellaceae_R-7_ group to regulate phenylalanine metabolism, which could reduce the fatty acid biosynthesis and fatty acid elongation in the mitochondria to lower blood lipids. Conclusively, we firstly confirmed the feasibility of Ce-RS3 for clinical application, which presents a novel, effective therapy for the mild hyperlipidemia. (Chictr. org. cn. Clinical study on anti-mild hyperlipidemia of Canna edulis RS3 resistant starch, ID Number: ChiCTR2200062871).

Magnolol-driven microbiota modulation elicits changes in tryptophan metabolism resulting in reduced skatole formation in pigs

Skatole of gut origin has garnered significant attention as a malodorous pollutant due to its escalating emissions, recalcitrance to biodegradation and harm to animal and human health. Magnolol is a health-promoting polyphenol with potential to considerably mitigate the skatole production in the intestines. To investigate the impact of magnolol and its underlying mechanism on the skatole formation, in vivo and in vitro experiments were conducted in pigs. Our results revealed that skatole concentrations in the cecum, colon, and faeces decreased by 58.24% (P = 0.088), 44.98% (P < 0.05) and 43.52% (P < 0.05), respectively, following magnolol supplementation. Magnolol supplementation significantly decreased the abundance of Lachnospira, Faecalibacterium, Paramuribaculum, Faecalimonas, Desulfovibrio, Bariatricus, and Mogibacterium within the colon (P < 0.05). Moreover, a strong positive correlation (P < 0.05) between skatole concentration and Desulfovibrio abundance was observed. Subsequent in silico studies showed that magnolol could dock well with indolepyruvate decarboxylase (IPDC) within Desulfovibrio. Further in vitro investigation unveiled that magnolol addition led to less indole-3-pyruvate diverted towards the oxidative skatole pathway by the potential docking of magnolol towards IPDC, thereby diminishing the conversion of substrate into skatole. Our findings offer novel targets and strategies for mitigating skatole emission from the source.

Promising dawn in the management of pulmonary hypertension: The mystery veil of gut microbiota

The gut microbiota is a complex community of microorganisms inhabiting the intestinal tract, which plays a vital role in human health. It is intricately involved in the metabolism, and it also affects diverse physiological processes. The gut-lung axis is a bidirectional pathway between the gastrointestinal tract and the lungs. Recent research has shown that the gut microbiome plays a crucial role in immune response regulation in the lungs and the development of lung diseases. In this review, we present the interrelated factors concerning gut microbiota and the associated metabolites in pulmonary hypertension (PH), a lethal disease characterized by elevated pulmonary vascular pressure and resistance. Our research team explored the role of gut-microbiota-derived metabolites in cardiovascular diseases and established the correlation between metabolites such as putrescine, succinate, trimethylamine N-oxide (TMAO), and N, N, N-trimethyl-5-aminovaleric acid with the diseases. Furthermore, we found that specific metabolites, such as TMAO and betaine, have significant clinical value in PH, suggesting their potential as biomarkers in disease management. In detailing the interplay between the gut microbiota, their metabolites, and PH, we underscored the potential therapeutic approaches modulating this microbiota. Ultimately, we endeavor to alleviate the substantial socioeconomic burden associated with this disease. This review presents a unique exploratory analysis of the link between gut microbiota and PH, intending to propel further investigations in the gut-lung axis.

Comprehensive analyses of a large human gut Bacteroidales culture collection reveal species and strain level diversity and evolution

Species of the Bacteroidales order are among the most abundant and stable bacterial members of the human gut microbiome with diverse impacts on human health. While Bacteroidales strains and species are genomically and functionally diverse, order-wide comparative analyses are lacking. We cultured and sequenced the genomes of 408 Bacteroidales isolates from healthy human donors representing nine genera and 35 species and performed comparative genomic, gene-specific, mobile gene, and metabolomic analyses. Families, genera, and species could be grouped based on many distinctive features. However, we also show extensive DNA transfer between diverse families, allowing for shared traits and strain evolution. Inter- and intra-specific diversity is also apparent in the metabolomic profiling studies. This highly characterized and diverse Bacteroidales culture collection with strain-resolved genomic and metabolomic analyses can serve as a resource to facilitate informed selection of strains for microbiome reconstitution.

Gut microbiota-dependent phenylacetylglutamine in cardiovascular disease: current knowledge and new insights

Phenylacetylglutamine (PAGln) is an amino acid derivate that comes from the amino acid phenylalanine. There are increasing studies showing that the level of PAGln is associated with the risk of different cardiovascular diseases. In this review, we discussed the metabolic pathway of PAGln production and the quantitative measurement methods of PAGln. We summarized the epidemiological evidence to show the role of PAGln in diagnostic and prognostic value in several cardiovascular diseases, such as heart failure, coronary heart disease/atherosclerosis, and cardiac arrhythmia. The underlying mechanism of PAGln is now considered to be related to the thrombotic potential of platelets via adrenergic receptors. Besides, other possible mechanisms such as inflammatory response and oxidative stress could also be induced by PAGln. Moreover, since PAGln is produced across different organs including the intestine, liver, and kidney, the cross-talk among multiple organs focused on the function of this uremic toxic metabolite. Finally, the prognostic value of PAGln compared to the classical biomarker was discussed and we also highlighted important gaps in knowledge and areas requiring future investigation of PAGln in cardiovascular diseases.

Prognostic value of gut microbe-generated metabolite phenylacetylglutamine in patients with heart failure

AIM

Phenylacetylglutamine (PAGln) is a phenylalanine-derived metabolite produced by gut microbiota with mechanistic links to heart failure (HF)-relevant phenotypes. We sought to investigate the prognostic value of PAGln in patients with stable HF.

METHODS AND RESULTS

Fasting plasma PAGln levels were measured by stable-isotope-dilution liquid chromatography-tandem mass spectrometry (LC-MS/MS) in patients with stable HF from two large cohorts. All-cause mortality was assessed at 5-year follow-up in the Cleveland cohort, and HF, hospitalization, or mortality were assessed at 3-year follow-up in the Berlin cohort. Within the Cleveland cohort, median PAGln levels were 4.2 (interquartile range [IQR] 2.4-6.9) μM. Highest quartile of PAGln was associated with 3.09-fold increased mortality risk compared to lowest quartile. Following adjustments for traditional risk factors, as well as race, estimated glomerular filtration rate, amino-terminal pro-B-type natriuretic peptide, high-sensitivity C-reactive protein, left ventricular ejection fraction, ischaemic aetiology, and HF drug treatment, elevated PAGln levels remained predictive of 5-year mortality in quartile comparisons (adjusted hazard ratio [HR] [95% confidence interval, CI] for Q4 vs Q1: 1.64 [1.07-2.53]). In the Berlin cohort, a similar distribution of PAGln levels was observed (median 3.2 [IQR 2.0-4.8] μM), and PAGln levels were associated with a 1.92-fold increase in 3-year HF hospitalization or all-cause mortality risk (adjusted HR [95% CI] for Q4 vs Q1: 1.92 [1.02-3.61]). Prognostic value of PAGln appears to be independent of trimethylamine N-oxide levels.

CONCLUSION

High levels of PAGln are associated with adverse outcomes independent of traditional cardiac risk factors and cardio-renal risk markers.

Role of the Gut Bacteria-Derived Metabolite Phenylacetylglutamine in Health and Diseases

Over the past few decades, it has been well established that gut microbiota-derived metabolites can disrupt gut function, thus resulting in an array of diseases. Notably, phenylacetylglutamine (PAGln), a bacterial derived metabolite, has recently gained attention due to its role in the initiation and progression of cardiovascular and cerebrovascular diseases. This meta-organismal metabolite PAGln is a byproduct of amino acid acetylation of its precursor phenylacetic acid (PAA) from a range of dietary sources like egg, meat, dairy products, etc. The microbiota-dependent metabolism of phenylalanine produces PAA, which is a crucial intermediate that is catalyzed by diverse microbial catalytic pathways. PAA conjugates with glutamine and glycine in the liver and kidney to predominantly form phenylacetylglutamine in humans and phenylacetylglycine in rodents. PAGln is associated with thrombosis as it enhances platelet activation mediated through the GPCRs receptors α2A, α2B, and β2 ADRs, thereby aggravating the pathological conditions. Clinical evidence suggests that elevated levels of PAGln are associated with pathology of cardiovascular, cerebrovascular, and neurological diseases. This Review further consolidates the microbial/biochemical synthesis of PAGln and discusses its role in the above pathophysiologies.

Advancing lifelong precision medicine for cardiovascular diseases through gut microbiota modulation

The gut microbiome is known as the tenth system of the human body that plays a vital role in the intersection between health and disease. The considerable inter-individual variability in gut microbiota poses both challenges and great prospects in promoting precision medicine in cardiovascular diseases (CVDs). In this review, based on the development, evolution, and influencing factors of gut microbiota in a full life circle, we summarized the recent advances on the characteristic alteration in gut microbiota in CVDs throughout different life stages, and depicted their pathological links in mechanism, as well as the highlight achievements of targeting gut microbiota in CVDs prevention, diagnosis and treatment. Personalized strategies could be tailored according to gut microbiota characteristics in different life stages, including gut microbiota-blood metabolites combined prediction and diagnosis, dietary interventions, lifestyle improvements, probiotic or prebiotic supplements. However, to fulfill the promise of a lifelong cardiovascular health, more mechanism studies should progress from correlation to causality and decipher novel mechanisms linking specific microbes and CVDs. It is also promising to use the burgeoning artificial intelligence and machine learning to target gut microbiota for developing diagnosis system and screening for new therapeutic interventions.

Gut microbiota and metabolite interface-mediated hepatic inflammation

Immunologic and metabolic signals regulated by gut microbiota and relevant metabolites mediate bidirectional interaction between the gut and liver. Gut microbiota dysbiosis, due to diet, lifestyle, bile acids, and genetic and environmental factors, can advance the progression of chronic liver disease. Commensal gut bacteria have both pro- and anti-inflammatory effects depending on their species and relative abundance in the intestine. Components and metabolites derived from gut microbiota-diet interaction can regulate hepatic innate and adaptive immune cells, as well as liver parenchymal cells, significantly impacting liver inflammation. In this mini review, recent findings of specific bacterial species and metabolites with functions in regulating liver inflammation are first reviewed. In addition, socioeconomic and environmental factors, hormones, and genetics that shape the profile of gut microbiota and microbial metabolites and components with the function of priming or dampening liver inflammation are discussed. Finally, current clinical trials evaluating the factors that manipulate gut microbiota to treat liver inflammation and chronic liver disease are reviewed. Overall, the discussion of microbial and metabolic mediators contributing to liver inflammation will help direct our future studies on liver disease.

Gut microbiota dysbiosis -associated obesity and its involvement in cardiovascular diseases and type 2 diabetes. A systematic review

INTRODUCTION

Obesity is a complex, multifactorial disease caused by various factors. Recently, the role of the gut microbiota in the development of obesity and its complications has attracted increasing interest.

PURPOSE

This article focuses on the mechanisms by which gut microbiota dysbiosis induces insulin resistance, type 2 diabetes, and cardiovascular diseases linked to obesity, highlighting the mechanisms explaining the role of gut microbiota dysbiosis-associated inflammation in the onset of these pathologies.

METHODS

A systematic study was carried out to understand and summarize the published results on this topic. More than 150 articles were included in this search, including different types of studies, consulted by an online search in English using various electronic search databases and predefined keywords related to the objectives of our study.

RESULTS

We have summarized the data from the articles consulted in this search, and we have found a major gut microbiota alteration in obesity, characterized by a specific decrease in butyrate-producing bacteria and the production of metabolites and components that lead to metabolic impairments and affect the progression of various diseases associated with obesity through distinct signaling pathways, including insulin resistance, type 2 diabetes, and cardiovascular diseases (CVD). We have also focused on the major role of inflammation as a link between gut microbiota dysbiosis and obesity-associated metabolic complications by explaining the mechanisms involved.

CONCLUSION

Gut microbiota dysbiosis plays a crucial role in the development of various obesity-related metabolic abnormalities, among them type 2 diabetes and CVD, and represents a major challenge for chronic disease prevention and health. Indeed, the intestinal microbiota appears to be a promising target for the nutritional or therapeutic management of these diseases.

Advances in synthetic biology toolboxes paving the way for mechanistic understanding and strain engineering of gut commensal Bacteroides spp. and Clostridium spp

The gut microbiota plays a significant role in influencing human immunity, metabolism, development, and behavior by producing a wide range of metabolites. While there is accumulating data on several microbiota-derived small molecules that contribute to host health and disease, our knowledge regarding the molecular mechanisms underlying metabolite-mediated microbe-host interactions remains limited. This is primarily due to the lack of efficient genetic tools for most commensal bacteria, especially those belonging to the dominant phyla Bacteroides spp. and Clostridium spp., which hinders the application of synthetic biology to these gut commensal bacteria. In this review, we provide an overview of recent advances in synthetic biology tools developed for the two dominant genera, as well as their applications in deciphering the mechanisms of microbe-host interactions mediated by microbiota-derived small molecules. We also discuss the potential biomedical applications of engineering commensal bacteria using these toolboxes. Finally, we share our perspective on the future development of synthetic biology tools for a better understanding of small molecule-mediated microbe-host interactions and their engineering for biomedical purposes.

Gut Microbiome-Generated Phenylacetylglutamine from Dietary Protein is Associated with Crohn's Disease and Exacerbates Colitis in Mouse Model Possibly via Platelet Activation

OBJECTIVES

Our aims were to better understand the interplay of diet and gut microbiota in Crohn's disease [CD], taking advantage of a new-onset treatment-naïve CD cohort. We focus on phenylacetylglutamine [PAGln], a diet-derived meta-organismal prothrombotic metabolite.

DESIGN

We collected faecal and serum samples from a CD cohort [n = 136] and healthy controls [n = 126] prior to treatment, and quantified serum PAGln using LC-MS/MS. Diet was assessed using food-frequency questionnaires. Mice [C57BL/6] were fed high/low-protein diets and administered dextran sodium sulphate [DSS] to examine plasma PAGly, thrombosis potential, and colitis severity. PAGly or saline was administered to DSS-induced colitis mice, and colitis severity and colonic tissue gene expression were examined. P-selectin and CD40L expression were determined in human platelet-rich plasma [n = 5-6] after exposure to platelet agonists following PAGln priming. Bioinformatic analysis and bacterial culturing identified the main contributor of PAGln in CD.

RESULTS

PAGln, a meta-organismal prothrombotic metabolite, is associated with CD. Administration of PAGly exacerbated colitis in a mouse model and upregulated coagulation-related biological processes. Antiplatelet medicine, dipyridamole, attenuated PAGly-enhanced colitis susceptibility. PAGln enhanced platelet activation and CD40L expression in platelet-rich plasma ex vivo. Further study revealed that high dietary protein intake and increased abundance of phenylacetic acid [PAA]-producing Proteobacteria mediated by phenylpyruvate decarboxylase act in concert to cause the elevated PAGln levels in CD patients.

CONCLUSION

Taken together, ppdc-carrying Proteobacteria-generated PAGln from dietary protein is associated with CD and exacerbates colitis possibly via platelet-induced coagulation and inflammation These results suggest that PAGln is a potential early diagnostic marker and therapeutic target of CD.

Microbe-derived uremic solutes enhance thrombosis potential in the host

p-Cresol sulfate (pCS) and indoxyl sulfate (IS), gut microbiome-derived metabolites, are traditionally associated with cardiovascular disease (CVD) risks in the setting of impaired kidney function. While pharmacologic provision of pCS or IS can promote pro-thrombotic phenotypes, neither the microbial enzymes involved nor direct gut microbial production have been linked to CVD. Untargeted metabolomics was performed on a discovery cohort (n = 1,149) with relatively preserved kidney function, followed by stable isotope-dilution mass spectrometry quantification of pCS and IS in an independent validation cohort (n = 3,954). Genetic engineering of human commensals to produce p-cresol and indole gain-of-function and loss-of-function mutants, followed by colonization of germ-free mice, and studies on host thrombosis were performed. Systemic pCS and IS levels were independently associated with all-cause mortality. Both in vitro and within colonized germ-free mice p-cresol productions were recapitulated by collaboration of two organisms: a Bacteroides strain that converts tyrosine to 4-hydroxyphenylacetate, and a Clostridium strain that decarboxylates 4-hydroxyphenylacetate to p-cresol. We then engineered a single organism, Bacteroides thetaiotaomicron, to produce p-cresol, indole, or both metabolites. Colonizing germ-free mice with engineered strains, we show the gut microbial genes for p-cresol (hpdBCA) and indole (tryptophanase) are sufficient to confer a pro-thrombotic phenotype in vivo. Moreover, human fecal metagenomics analyses show that abundances of hpdBCA and tryptophanase are associated with CVD. These studies show that pCS and IS, two abundant microbiome-derived metabolites, play a broader potential role in CVD than was previously known. They also suggest that therapeutic targeting of gut microbial p-cresol- and indole-producing pathways represent rational targets for CVD.IMPORTANCEAlterations in gut microbial composition and function have been linked to numerous diseases. Identifying microbial pathways responsible for producing molecules that adversely impact the host is an important first step in the development of therapeutic interventions. Here, we first use large-scale clinical observations to link blood levels of defined microbial products to cardiovascular disease risks. Notably, the previously identified uremic toxins p-cresol sulfate and indoxyl sulfate were shown to predict 5-year mortality risks. After identifying the microbes and microbial enzymes involved in the generation of these uremic toxins, we used bioengineering technologies coupled with colonization of germ-free mice to show that the gut microbial genes that generate p-cresol and indole are sufficient to confer p-cresol sulfate and indoxyl sulfate formation, and a pro-thrombotic phenotype in vivo. The findings and tools developed serve as a critical step in both the study and targeting of these gut microbial pathways in vivo.

Gut commensals and their metabolites in health and disease

Purpose of review

This review comprehensively discusses the role of the gut microbiome and its metabolites in health and disease and sheds light on the importance of a holistic approach in assessing the gut.

Recent findings

The gut microbiome consisting of the bacteriome, mycobiome, archaeome, and virome has a profound effect on human health. Gut dysbiosis which is characterized by perturbations in the microbial population not only results in gastrointestinal (GI) symptoms or conditions but can also give rise to extra-GI manifestations. Gut microorganisms also produce metabolites (short-chain fatty acids, trimethylamine, hydrogen sulfide, methane, and so on) that are important for several interkingdom microbial interactions and functions. They also participate in various host metabolic processes. An alteration in the microbial species can affect their respective metabolite concentrations which can have serious health implications. Effective assessment of the gut microbiome and its metabolites is crucial as it can provide insights into one's overall health.

Summary

Emerging evidence highlights the role of the gut microbiome and its metabolites in health and disease. As it is implicated in GI as well as extra-GI symptoms, the gut microbiome plays a crucial role in the overall well-being of the host. Effective assessment of the gut microbiome may provide insights into one's health status leading to more holistic care.

Increased circulating phenylacetylglutamine concentration elevates the predictive value of cardiovascular event risk in heart failure patients

BACKGROUND

Phenylacetylglutamine (PAGln)-a newly discovered microbial metabolite produced by phenylalanine metabolism-is reportedly associated with cardiovascular events via adrenergic receptors. Nonetheless, its association with cardiovascular outcomes in heart failure (HF) patients remains unknown.

OBJECTIVES

This study aimed to prospectively investigate the prognostic value of PAGln for HF.

METHODS

Plasma PAGln levels were quantified by liquid chromatography-tandem mass spectrometry. We first assessed the association between plasma PAGln levels and the incidence of adverse cardiovascular events in 3152 HF patients (including HF with preserved and reduced ejection fraction) over a median follow-up period of 2 years. The primary endpoint was the composite of cardiovascular death or heart transplantation. We then assessed the prognostic role of PAGln in addition to the classic biomarker N-terminal pro-B-type natriuretic peptide (NT-proBNP). The correlation between PAGln levels and β-blocker use was also investigated.

RESULTS

In total, 520 cardiovascular deaths or heart transplantations occurred in the HF cohort. Elevated PAGln levels were independently associated with a higher risk of the primary endpoint in a dose-response manner, regardless of HF subtype. Concurrent assessment of PAGln and NT-proBNP levels enhanced risk stratification among HF patients. PAGln further showed prognostic value at low NT-proBNP levels. Additionally, the interaction effects between PAGln and β-blocker use were not significant.

CONCLUSIONS

Plasma PAGln levels are an independent predictor of an increased risk of adverse cardiovascular events in HF. Our work could provide joint and complementary prognostic value to NT-proBNP levels in HF patients.

Breaking bugs: gut microbes metabolize dietary components and modulate vascular health

Gut microbiota modulates host physiology and pathophysiology through the production of microbial metabolites. Diet is a crucial factor in shaping the microbiome, and gut microbes interact with the host by producing beneficial or detrimental diet-derived microbial metabolites. Evidence from our lab and others indicates that the interaction between diet and gut microbes plays a pivotal role in modulating vascular health. Diet-derived microbial metabolites such as short-chain fatty acids and metabolites of phenolic acids improve vascular health, whereas trimethylamine oxide and certain amino acid-derived microbial metabolites impair the vasculature. These metabolites have been shown to regulate blood pressure, vascular inflammation, and atherosclerosis by acting on multiple targets. Nonetheless, there are substantial gaps in knowledge within this field. The microbial enzymes essential for the production of diet-derived metabolites, the role of the food matrix in regulating the bioavailability of metabolites, and the structure-activity relationships between metabolites and biomolecules in the vasculature are largely unknown. Potential diet-derived metabolites to improve vascular health can be identified through future studies that investigate the causal relationship between dietary components, gut microbes, diet-derived metabolites, and vascular health by using radiolabeled compounds, metabolomics, transcriptomics, and proteomics techniques.

Atlas of gut microbe-derived products from aromatic amino acids and risk of cardiovascular morbidity and mortality

AIMS

Precision microbiome modulation as a novel treatment strategy is a rapidly evolving and sought goal. The aim of this study is to determine relationships among systemic gut microbial metabolite levels and incident cardiovascular disease risks to identify gut microbial pathways as possible targets for personalized therapeutic interventions.

METHODS AND RESULTS

Stable isotope dilution mass spectrometry methods to quantitatively measure aromatic amino acids and their metabolites were used to examine sequential subjects undergoing elective diagnostic cardiac evaluation in two independent cohorts with longitudinal outcome data [US (n = 4000) and EU (n = 833) cohorts]. It was also used in plasma from humans and mice before vs. after a cocktail of poorly absorbed antibiotics to suppress gut microbiota. Multiple aromatic amino acid-derived metabolites that originate, at least in part, from gut bacteria are associated with incident (3-year) major adverse cardiovascular event (MACE) risks (myocardial infarction, stroke, or death) and all-cause mortality independent of traditional risk factors. Key gut microbiota-derived metabolites associated with incident MACE and poorer survival risks include: (i) phenylacetyl glutamine and phenylacetyl glycine (from phenylalanine); (ii) p-cresol (from tyrosine) yielding p-cresol sulfate and p-cresol glucuronide; (iii) 4-OH-phenyllactic acid (from tyrosine) yielding 4-OH-benzoic acid and 4-OH-hippuric acid; (iv) indole (from tryptophan) yielding indole glucuronide and indoxyl sulfate; (v) indole-3-pyruvic acid (from tryptophan) yielding indole-3-lactic acid and indole-3-acetyl-glutamine, and (vi) 5-OH-indole-3-acetic acid (from tryptophan).

CONCLUSION

Key gut microbiota-generated metabolites derived from aromatic amino acids independently associated with incident adverse cardiovascular outcomes are identified, and thus will help focus future studies on gut-microbial metabolic outputs relevant to host cardiovascular health.

Disturbed lipid profile in common variable immunodeficiency - a pathogenic loop of inflammation and metabolic disturbances

The relationship between metabolic and inflammatory pathways play a pathogenic role in various cardiometabolic disorders and is potentially also involved in the pathogenesis of other disorders such as cancer, autoimmunity and infectious diseases. Common variable immunodeficiency (CVID) is the most common primary immunodeficiency in adults, characterized by increased frequency of airway infections with capsulated bacteria. In addition, a large proportion of CVID patients have autoimmune and inflammatory complications associated with systemic inflammation. We summarize the evidence that support a role of a bidirectional pathogenic interaction between inflammation and metabolic disturbances in CVID. This include low levels and function of high-density lipoprotein (HDL), high levels of triglycerides (TG) and its major lipoprotein very low-density lipoprotein (VLDL), and an unfavorable fatty acid (FA) profile. The dysregulation of TG, VLDL and FA were linked to disturbed gut microbiota profile, and TG and VLDL levels were strongly associated with lipopolysaccharides (LPS), a marker of gut leakage in blood. Of note, the disturbed lipid profile in CVID did not include total cholesterol levels or high low-density lipoprotein levels. Furthermore, increased VLDL and TG levels in blood were not associated with diet, high body mass index and liver steatosis, suggesting a different phenotype than in patients with traditional cardiovascular risk such as metabolic syndrome. We hypothesize that these metabolic disturbances are linked to inflammation in a bidirectional manner with disturbed gut microbiota as a potential contributing factor.

Dietary Patterns, Gut Microbiota Remodeling, and Cardiometabolic Disease

The cardiovascular and metabolic disorders, collectively known as cardiometabolic disease (CMD), are high morbidity and mortality pathologies associated with lower quality of life and increasing health-care costs. The influence of the gut microbiota (GM) in dictating the interpersonal variability in CMD susceptibility, progression and treatment response is beginning to be deciphered, as is the mutualistic relation established between the GM and diet. In particular, dietary factors emerge as pivotal determinants shaping the architecture and function of resident microorganisms in the human gut. In turn, intestinal microbes influence the absorption, metabolism, and storage of ingested nutrients, with potentially profound effects on host physiology. Herein, we present an updated overview on major effects of dietary components on the GM, highlighting the beneficial and detrimental consequences of diet-microbiota crosstalk in the setting of CMD. We also discuss the promises and challenges of integrating microbiome data in dietary planning aimed at restraining CMD onset and progression with a more personalized nutritional approach.

Gut Microbiota and Microbial Metabolism in Early Risk of Cardiometabolic Disease

Cardiometabolic disease comprises cardiovascular and metabolic dysfunction and underlies the leading causes of morbidity and mortality, both within the United States and worldwide. Commensal microbiota are implicated in the development of cardiometabolic disease. Evidence suggests that the microbiome is relatively variable during infancy and early childhood, becoming more fixed in later childhood and adulthood. Effects of microbiota, both during early development, and in later life, may induce changes in host metabolism that modulate risk mechanisms and predispose toward the development of cardiometabolic disease. In this review, we summarize the factors that influence gut microbiome composition and function during early life and explore how changes in microbiota and microbial metabolism influence host metabolism and cardiometabolic risk throughout life. We highlight limitations in current methodology and approaches and outline state-of-the-art advances, which are improving research and building toward refined diagnosis and treatment options in microbiome-targeted therapies.

Neuron-immunity communication: mechanism of neuroprotective effects in EGCG

Epigallocatechin gallate (EGCG), a naturally occurring active ingredient unique to tea, has been shown to have neuroprotective potential. There is growing evidence of its potential advantages in the prevention and treatment of neuroinflammation, neurodegenerative diseases, and neurological damage. Neuroimmune communication is an important physiological mechanism in neurological diseases, including immune cell activation and response, cytokine delivery. EGCG shows great neuroprotective potential by modulating signals related to autoimmune response and improving communication between the nervous system and the immune system, effectively reducing the inflammatory state and neurological function. During neuroimmune communication, EGCG promotes the secretion of neurotrophic factors into the repair of damaged neurons, improves intestinal microenvironmental homeostasis, and ameliorates pathological phenotypes through molecular and cellular mechanisms related to the brain-gut axis. Here, we discuss the molecular and cellular mechanisms of inflammatory signaling exchange involving neuroimmune communication. We further emphasize that the neuroprotective role of EGCG is dependent on the modulatory role between immunity and neurology in neurologically related diseases.

Microbiota-related metabolites fueling the understanding of ischemic heart disease

Up-to-date knowledge of gut microbial taxa associated with ischemic heart disease (IHD). Microbial metabolites for mechanistic dissection of IHD pathology. Microbiome-based therapies in IHD prevention and treatment.

Meta-organismal metabolism in cardiovascular disease

Host and microbe cooperate to generate bioactive metabolites with significant scientific and clinical importance. In this issue of Cell Host & Microbe, Zhu, Dwidar et al. identify parallel microbial pathways that transform dietary amino acids into the precursors of deleterious host-derived metabolites and confirm their correlation to adverse cardiovascular health.