The diet–microbe morbid union

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Guardians of Immunity: Advances in Primary Immunodeficiency Disorders and Management

Primary immunodeficiency disorders (PIDs) are a heterogeneous group of genetic conditions profoundly impacting immune function. The investigation spans various PID categories, offering insights into their distinct pathogenic mechanisms and clinical manifestations. Within the adaptive immune system, B-cell, T-cell, and combined immunodeficiencies are dissected, emphasizing their critical roles in orchestrating effective immune responses. In the realm of the innate immune system, focus is directed toward phagocytes and complement deficiencies, underscoring the pivotal roles of these components in initial defense against infections. Furthermore, the review delves into disorders of immune dysregulation, encompassing hemophagocytic lymphohistiocytosis (HLH), autoimmune lymphoproliferative syndrome (ALPS), immune dysregulation, polyendocrinopathy, enteropathy, and X-linked(IPEX), and autoimmunity polyendocrinopathy candidiasis-ectodermal dystrophy(APECED), elucidating the intricate interplay between immune tolerance and autoimmunity prevention. Diagnostic strategies for PIDs are explored, highlighting advancements in genetic and molecular techniques that enable precise identification of underlying genetic mutations and alterations in immune function. We have also outlined treatment modalities for PIDs, which often entail a multidisciplinary approach involving immunoglobulin replacement, antimicrobial prophylaxis, and, in select cases, hematopoietic stem cell transplantation. Emerging therapies, including gene therapy, hold promise for targeted interventions. In essence, this review encapsulates the complexity of PIDs, emphasizing the critical importance of early diagnosis and tailored therapeutic interventions. As research advances, a clearer understanding of these disorders emerges, fostering optimism for enhanced patient care and management in the future.

Neither Trimethylamine-N-Oxide nor Trimethyllysine Is Associated with Atherosclerosis: A Cross-Sectional Study in Older Japanese Adults

Recent evidence suggests that trimethylamine-N-oxide (TMAO), a metabolite of L-carnitine and choline, is linked to atherosclerosis and cardiovascular diseases. As TMAO content is very high in fish, we raised the following question: why do Japanese people, who consume lots of fish, show a low risk of atherosclerosis? To address this question, we investigated the effects of TMAO and other L-carnitine-related metabolites on carotid intima-media thickness (IMT). Participants were recruited from a small island and a mountainous region. Plasma L-carnitine, γ-butyrobetaine (γBB), TMAO, trimethyllysine (TML), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) levels were measured using liquid or gas chromatography-mass spectrometry. Plasma L-carnitine concentration was higher in men than in women. TMAO and TML were significantly higher in the residents of the island than in the mountainous people. In multiple linear regression analyses in all participants, TML showed a significant inverse association with max-IMT and plaque score (PS), whereas TMAO did not show any associations. In women, L-carnitine was positively associated with max-IMT and PS. TMAO was correlated with both EPA and DHA levels, implying that fish is a major dietary source of TMAO in Japanese people. Our study found that plasma TMAO was not an apparent risk factor for atherosclerosis in elderly Japanese people, whereas a low level of TML might be a potential risk. L-carnitine may be a marker for atherosclerosis in women.

Probiotics: Potential Novel Therapeutics Against Fungal Infections

The global infection rate of fungal diseases is increasing year by year, and it has gradually become one of the most serious infectious diseases threatening human health. However, the side effects of antifungal drugs and the fungal resistance to these drugs are gradually increasing. Therefore, the development of new broad-spectrum, safe, and economical alternatives to antibacterial drugs are essential. Probiotics are microorganisms that are beneficial for human health. They boost human immunity, resist pathogen colonization, and reduce pathogen infection. Many investigations have shown their inhibitory activity on a wide range of pathogenic fungi. However, their antibacterial mechanism is still a secret. This article reviews the progress of probiotics as a new method for the treatment of fungal diseases.

Bacterial metabolites and cardiovascular risk in children with chronic kidney disease

Cardiovascular complications are the major cause of the marked morbidity and mortality associated with chronic kidney disease (CKD). The classical cardiovascular risk factors such as diabetes and hypertension undoubtedly play a role in the development of cardiovascular disease (CVD) in adult CKD patients; however, CVD is just as prominent in children with CKD who do not have these risk factors. Hence, the CKD-specific pathophysiology of CVD remains incompletely understood. In light of this, studying children with CKD presents a unique opportunity to analyze CKD-associated mechanisms of CVD more specifically and could help to unveil novel therapeutic targets.

Here, we comprehensively review the interaction of the human gut microbiome and the microbial metabolism of nutrients with host immunity and cardiovascular end-organ damage. The human gut microbiome is evolutionary conditioned and modified throughout life by endogenous factors as well as environmental factors. Chronic diseases, such as CKD, cause significant disruption to the composition and function of the gut microbiome and lead to disease-associated dysbiosis. This dysbiosis and the accompanying loss of biochemical homeostasis in the epithelial cells of the colon can be the result of poor diet (e.g., low-fiber intake), medications, and underlying disease. As a result of dysbiosis, bacteria promoting proteolytic fermentation increase and those for saccharolytic fermentation decrease and the integrity of the gut barrier is perturbed (leaky gut). These changes disrupt local metabolite homeostasis in the gut and decrease productions of the beneficial short-chain fatty acids (SCFAs). Moreover, the enhanced proteolytic fermentation generates unhealthy levels of microbially derived toxic metabolites, which further accumulate in the systemic circulation as a consequence of impaired kidney function. We describe possible mechanisms involved in the increased systemic inflammation in CKD that is associated with the combined effect of SCFA deficiency and accumulation of uremic toxins. In the future, a more comprehensive and mechanistic understanding of the gut–kidney–heart interaction, mediated largely by immune dysregulation and inflammation, might allow us to target the gut microbiome more specifically in order to attenuate CKD-associated comorbidities.

Lipid, fatty acid, carnitine- and choline derivative profiles in rheumatoid arthritis outpatients with different degrees of periodontal inflammation

Rheumatoid arthritis (RA) and periodontitis are chronic inflammatory diseases with several pathogenic pathways in common. Evidence supports an association between the diseases, but the exact underlying mechanisms behind the connection are still under investigation. Lipid, fatty acid (FA) and metabolic profile alterations have been associated with several chronic inflammatory diseases, including RA and periodontitis. Mitochondria have a central role in regulating cellular bioenergetic and whole-body metabolic homeostasis, and mitochondrial dysfunction has been proposed as a possible link between the two disorders. The aim of this cross-sectional study was to explore whole-blood FA, serum lipid composition, and carnitine- and choline derivatives in 78 RA outpatients with different degrees of periodontal inflammation. The main findings were alterations in lipid, FA, and carnitine- and choline derivative profiles. More specifically, higher total FA and total cholesterol concentrations were found in active RA. Elevated phospholipid concentrations with concomitant lower choline, elevated medium-chain acylcarnitines (MC-AC), and decreased ratios of MC-AC and long-chain (LC)-AC were associated with prednisolone medication. This may indicate an altered mitochondrial function in relation to the increased inflammatory status in RA disease. Our findings may support the need for interdisciplinary collaboration within the field of medicine and dentistry in patient stratification to improve personalized treatment. Longitudinal studies should be conducted to further assess the potential impact of mitochondrial dysfunction on RA and periodontitis.

The effect of egg and its derivatives on vascular function: A systematic review of interventional studies

BACKGROUND & AIMS

Cardiovascular diseases (CVDs) are considered as a major cause of health loss for all regions of the world. Atherosclerosis is one of the most important underlying causes of CVDs. Vascular dysfunction is the primary marker of atherosclerosis. Various studies have investigated the effect of egg intake on CVDs. This study aimed to determine the effect of egg and its derivatives consumption on vascular function.

METHODS

Using a comprehensive search strategy, the searching was conducted on PubMed, Scopus and Google Scholar search engines resources (from inception up to Feb 2020). Intended exposure and outcome were egg or its derivatives intake, and vascular function measuring methods, respectively.

RESULTS

A total of 35 papers were found through search databases. Finally, seven trials were included, which were published between 2005 and 2018. Results showed that acute and chronic consumption of whole eggs did not have a significant adverse effect on flow-mediated dilatation (FMD). Also, lutein-enriched egg yolk and egg ovalbumin-derived protein hydrolysate did not have significant positive effects on FMD and pulse wave velocity (PWV), respectively. However, one month egg-yolk-derived phospholipid (PL) preparation intervention increased FMD by 3.4% (p < 0.05), and replacing a portion of a glucose challenge with whole eggs or egg whites improved postprandial FMD (p < 0.05).

CONCLUSIONS

We concluded that consumption of whole egg, despite being rich in cholesterol, has no adverse effect on vascular function, and even some of egg derivatives may improve vascular function. Further research is needed to justify the potential effects of egg or its derivatives on vascular function.

Archaea, specific genetic traits, and development of improved bacterial live biotherapeutic products: another face of next-generation probiotics

Trimethylamine (TMA) and its oxide TMAO are important biomolecules involved in disease-associated processes in humans (e.g., trimethylaminuria and cardiovascular diseases). TMAO in plasma (pTMAO) stems from intestinal TMA, which is formed from various components of the diet in a complex interplay between diet, gut microbiota, and the human host. Most approaches to prevent the occurrence of such deleterious molecules focus on actions to interfere with gut microbiota metabolism to limit the synthesis of TMA. Some human gut archaea however use TMA as terminal electron acceptor for producing methane, thus indicating that intestinal TMA does not accumulate in some human subjects. Therefore, a rational alternative approach is to eliminate neo-synthesized intestinal TMA. This can be achieved through bioremediation of TMA by these peculiar methanogenic archaea, either by stimulating or providing them, leading to a novel kind of next-generation probiotics referred to as archaebiotics. Finally, specific components which are involved in this archaeal metabolism could also be used as intestinal TMA sequesters, facilitating TMA excretion along with stool. Referring to a standard pharmacological approach, these TMA traps could be synthesized ex vivo and then delivered into the human gut. Another approach is the engineering of known probiotic strain in order to metabolize TMA, i.e., live engineered biotherapeutic products. These alternatives would require, however, to take into account the necessity of synthesizing the 22nd amino acid pyrrolysine, i.e., some specificities of the genetics of TMA-consuming archaea. Here, we present an overview of these different strategies and recent advances in the field that will sustain such biotechnological developments. KEY POINTS: • Some autochthonous human archaea can use TMA for their essential metabolism, a methyl-dependent hydrogenotrophic methanogenesis. • They could therefore be used as next-generation probiotics for preventing some human diseases, especially cardiovascular diseases and trimethylaminuria. • Their genetic capacities can also be used to design live recombinant biotherapeutic products. • Encoding of the 22nd amino acid pyrrolysine is necessary for such alternative developments.

Trimethylamine N-Oxide Generated by the Gut Microbiota Is Associated with Vascular Inflammation: New Insights into Atherosclerosis

Trimethylamine N-oxide (TMAO) is a biologically active molecule generated by the gut microbiota. Accumulating evidences have indicated a close association between high plasma TMAO levels and the risk of developing atherosclerosis (AS). AS is considered a chronic inflammatory disease initiated by vascular endothelial inflammatory injury. Both observational and experimental studies suggest that TMAO can cause endothelial inflammatory injury. However, a clear mechanistic link between TMAO and vascular inflammation of AS is not yet summarized. In this review, we discuss the association between TMAO and AS and focus on the potential role of TMAO in endothelial inflammatory injury. Finally, the utility of TMAO-targeted therapeutic strategies for the treatment of AS is also analyzed.

Trimethylamine-N-oxide has prognostic value in coronary heart disease: a meta-analysis and dose-response analysis

Background

Previous clinical studies have suggested that trimethylamine-N-oxide (TMAO) could contribute to the development of atherosclerosis cardiovascular disease. However, the synthetic analysis in coronary heart disease (CHD) was not yet performed. We aimed to clarify the relationship between elevated plasma concentrations of TMAO and the incidence of major adverse cardiovascular events (MACE) in CHD patients.

Methods

Meta-analysis and dose-response analysis of hazard ratio data from prospective observational studies reporting on the association between TMAO plasma concentrations and the incidence of MACE in patients with CHD were conducted.

Results

Of the 2369 published articles identified in the search, seven papers, with data from nine cohort studies (10,301 patients), were included in the meta-analysis. Combined data showed that elevated plasma TMAO concentrations could increase 58% higher risk of MACE in patients with CHD (hazard ratios [HR]: 1.58; 95% confidence interval [CI] = 1.35–1.84, P = 0.000). For follow-up ≥ 1 year, it was associated with 62% higher risk of MACE in patients with longer-term than shorter-term (HR for follow-up ≥ 4 years: 1.96; 95% CI = 1.52–2.52 vs one to 3 years: 1.34; 95% CI = 1.26–1.43, P = 0.004). The dose-response analysis revealed a ‘J’ shaped association between TMAO concentration and the incidence of MACE (P = 0.033), with the concentration above 5.1 μmol/L being associated with HR of > 1.

Conclusions

Elevated levels of TMAO are associated with an increased incidence of MACE in patients with CHD. TMAO concentration of 5.1 μmol/L may be a cut-off value for prognosis.

Potential Influences of Gut Microbiota on the Formation of Intracranial Aneurysm

Gut microbiota modulates metabolic and immunoregulatory axes and contributes to the pathophysiology of diseases with inflammatory components, such as atherosclerosis, diabetes mellitus, and ischemic stroke. Inflammation is emerging as a critical player in the pathophysiology of an intracranial aneurysm. Therefore, we hypothesized that the gut microbiota affects aneurysm formation by modulating inflammation. We induced intracranial aneurysms in mice by combining systemic hypertension and a single injection of elastase into the cerebrospinal fluid. Depletion of the gut microbiota was achieved via an oral antibiotic cocktail of vancomycin, metronidazole, ampicillin, and neomycin. Antibiotics were given 3 weeks before aneurysm induction and either continued until the end of the experiment or stopped 1 day before aneurysm induction. We also assessed the effects of the gut microbiota depletion on macrophage infiltration and mRNA levels of inflammatory cytokines. Gut microbiota depletion by antibiotics reduced the incidence when antibiotics were started 3 weeks before aneurysm induction and continued until the end of the experiment (83% versus 6%, P<0.001). Even when antibiotics were stopped 1 day before aneurysm induction, the gut microbiota depletion significantly reduced the incidence of aneurysms (86% versus 28%, P<0.05). Both macrophage infiltration and mRNA levels of inflammatory cytokines were reduced with gut microbiota depletion. These findings suggest that the gut microbiota contributes to the pathophysiology of aneurysms by modulating inflammation. Human studies are needed to determine the exact contribution of the gut microbiota to the pathophysiology of aneurysm formation and disease course in humans.

Metabolic products of the intestinal microbiome and extremes of atherosclerosis

BACKGROUND AND AIMS

There is increasing awareness that the intestinal microbiome plays an important role in human health. We investigated its role in the burden of carotid atherosclerosis, measured by ultrasound as total plaque area.

METHODS

Multiple regression with traditional risk factors was used to identify three phenotypes among 316/3056 patients attending vascular prevention clinics. Residual score (RES; i.e. the distance off the regression line, similar to standard deviation) was used to identify the 5% of patients with much less plaque than predicted by their risk factors (Protected, RES <-2), the 90% with about as much plaque as predicted (Explained, RES -2 to 2), and the 5% with much more plaque than predicted (Unexplained RES >2). Metabolic products of the intestinal microbiome that accumulate in renal failure - gut-derived uremic toxins (GDUT) - were assayed in plasma by ultra-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry.

RESULTS

Plasma levels of trimethylamine n-oxide (TMAO), p-cresyl sulfate, p-cresyl glucuronide, and phenylacetylglutamine were significantly lower among patients with the Protected phenotype, and higher in those with the Unexplained phenotype, despite no significant differences in renal function or in dietary intake of nutrient precursors of GDUT. In linear multiple regression with a broad panel of risk factors, TMAO (p = 0.011) and p-cresyl sulfate (p = 0.011) were significant independent predictors of carotid plaque burden.

CONCLUSIONS

The intestinal microbiome appears to play an important role in atherosclerosis. These findings raise the possibility of novel approaches to treatment of atherosclerosis such as fecal transplantation and probiotics.

Plant-based diets and cardiovascular health

Plant-based diets, defined in terms of low frequency of animal food consumption, have been increasingly recommended for their health benefits. Numerous studies have found plant-based diets, especially when rich in high quality plant foods such as whole grains, fruits, vegetables, and nuts, to be associated with lower risk of cardiovascular outcomes and intermediate risk factors. This review summarizes the current evidence base examining the associations of plant-based diets with cardiovascular endpoints, and discusses the potential biological mechanisms underlying their health effects, practical recommendations and applications of this research, and directions for future research. Healthful plant-based diets should be recommended as an environmentally sustainable dietary option for improved cardiovascular health.

Gut microbiota and chronic kidney disease: implications for novel mechanistic insights and therapeutic strategies

The complicated communities of microbiota colonizing the human gastrointestinal tract exert a strong function in health maintenance and disease prevention. Indeed, accumulating evidence has indicated that the intestinal microbiota plays a key role in the pathogenesis and development of chronic kidney disease (CKD). Modulation of the gut microbiome composition in CKD may contribute to the accumulation of gut-derived uremic toxins, high circulating level of lipopolysaccharides and immune deregulation, all of which play a critical role in the pathogenesis of CKD and CKD-associated complications. In this review, we discuss the recent findings on the potential impact of gut microbiota in CKD and the underlying mechanisms by which microbiota can influence kidney diseases and vice versa. Additionally, the potential efficacy of pre-, pro- and synbiotics in the restoration of healthy gut microbia is described in detail to provide future directions for research.

Vertebrate food products as a potential source of prion-like α-synuclein

The aberrant aggregation of the protein α-synuclein is thought to be involved in Parkinson’s disease (PD). However, the factors that lead to initiation and propagation of α-synuclein aggregation are not clearly understood. Recently, the hypothesis that α-synuclein aggregation spreads via a prion-like mechanism originating in the gut has gained much scientific attention. If α-synuclein spreads via a prion-like mechanism, then an important question becomes, what are the origins of this prion-like species? Here we review the possibility that α-synuclein aggregation could be seeded via the ingestion of a prion-like α-synuclein species contained within food products originating from vertebrates. To do this, we highlight current evidence for the gut-to-brain hypothesis of PD, and put this in context of available routes of α-synuclein prion infectivity via the gastrointestinal (GI) tract. We then discuss meat as a ready exogenous source of α-synuclein and how certain risk factors, including inflammation, may allow for dietary α-synuclein to pass from the GI lumen into the host to induce pathology. Lastly, we review epidemiological evidence that dietary factors may be involved in PD. Overall, research to date has yet to directly test the contribution of dietary α-synuclein to the mechanism of initiation and progression of the disease. However, numerous experimental findings, including the potent seeding and spreading behavior of α-synuclein fibrils, seem to support, at least in part, the feasibility of an infection with a prion α-synuclein particle via the GI tract. Further studies are required to determine whether dietary α-synuclein contributes to seeding pathology in the gut.

Beneficial effects of apple peel polyphenols on vascular endothelial dysfunction and liver injury in high choline-fed mice

This study was designed to investigate the preventive effects of Red Fuji apple peel polyphenolic extract (APP) on vascular endothelial dysfunction and liver injury in mice fed a high choline diet. The mice were fed 3% dietary choline in drinking water for 8 weeks and displayed vascular dysfunction and liver damage (p < 0.01). The administration of APP at 600 and 900 mg per kg bw significantly elevated serum NO, HDL and 6-Keto-PGF1a levels and lowered serum TC, TG, LDL, ET-1 and TXB2 levels in the HC-fed mice. Besides, APP also caused the reduction of AST, ALT activities and MDA, CRP, TNF-α levels, and increased the hepatic GSH-Px and SOD activities of the HC-fed mice. Furthermore, the histopathology of the liver by conventional H&E and oil red O staining confirmed the liver steatosis induced by a choline diet and the hepatoprotective effect of APP. The experiment results indicated that the polyphenolic extract from apple peel might be regarded as a preventive and therapeutic product for the amelioration of HC diet-induced vascular dysfunction and hepatic injury.

Choline and its metabolites are differently associated with cardiometabolic risk factors, history of cardiovascular disease, and MRI-documented cerebrovascular disease in older adults

Background: There is a potential role of choline in cardiovascular and cerebrovascular disease through its involvement in lipid and one-carbon metabolism.Objective: We evaluated the associations of plasma choline and choline-related compounds with cardiometabolic risk factors, history of cardiovascular disease, and cerebrovascular pathology.Design: A cross-sectional subset of the Nutrition, Aging, and Memory in Elders cohort who had undergone MRI of the brain (n = 296; mean ± SD age: 73 ± 8.1 y) was assessed. Plasma concentrations of free choline, betaine, and phosphatidylcholine were measured with the use of liquid-chromatography-stable-isotope dilution-multiple-reaction monitoring-mass spectrometry. A volumetric analysis of MRI was used to determine the cerebrovascular pathology (white-matter hyperintensities and small- and large-vessel infarcts). Multiple linear and logistic regression models were used to examine relations of plasma measures with cardiometabolic risk factors, history of cardiovascular disease, and radiologic evidence of cerebrovascular pathology.Results: Higher concentrations of plasma choline were associated with an unfavorable cardiometabolic risk-factor profile [lower high-density lipoprotein (HDL) cholesterol, higher total homocysteine, and higher body mass index (BMI)] and greater odds of large-vessel cerebral vascular disease or history of cardiovascular disease but lower odds of small-vessel cerebral vascular disease. Conversely, higher concentrations of plasma betaine were associated with a favorable cardiometabolic risk-factor profile [lower low-density lipoprotein (LDL) cholesterol and triglycerides] and lower odds of diabetes. Higher concentrations of plasma phosphatidylcholine were associated with characteristics of both a favorable cardiometabolic risk-factor profile (higher HDL cholesterol, lower BMI, lower C-reactive protein, lower waist circumference, and lower odds of hypertension and diabetes) and an unfavorable profile (higher LDL cholesterol and triglycerides).Conclusion: Choline and its metabolites have differential associations with cardiometabolic risk factors and subtypes of vascular disease, thereby suggesting differing roles in the pathogenesis of cardiovascular and cerebral large-vessel disease compared with that of small-vessel disease.

Understanding Luminal Microorganisms and Their Potential Effectiveness in Treating Intestinal Inflammation

The human intestine contains 10¹⁴ bacteria, which outnumber the mammalian cells 10-fold. Certain other commensal or infectious agents, like helminthic parasites, become members of this microbial ecosystem, especially in populations living under less hygienic conditions. Intestinal microbes, also called the microbiome or microbiota, shape the host immune reactivity to self and nonself throughout life. Changes in microbiome composition may impair the maturation of immune regulatory pathways and predispose the host to develop various forms of inflammatory disorders, like Crohn's disease or ulcerative colitis. The microbiome is also critical to successful transplantation of organs or grafts. After allogeneic hematopoietic stem cell transplantation, when the new donor cells, such as T lymphocytes learn to discriminate "the new self from nonself" in the transplant recipient, they need healthy microbiota-derived signals to preserve the immune homeostasis. Restoring microbiota through intestinal delivery of bacterial strains, helminths, fecal microbiota transplantation, or stool substitutes have the potential to improve and correct aberrant immune reactivity in various disorders.

Does our gut microbiome predict cardiovascular risk? A review of the evidence from metabolomics

Millions of microbes are found in the human gut, and are collectively referred as the gut microbiota. Recent studies have estimated that the microbiota genome contains 100-fold more genes than the host genome. These microbiota contribute to digestion by processing energy substrates unutilized by the host, with about half of the total genome of the gut microbiota being related to central carbon and amino acid metabolism as well as the biosynthesis of secondary metabolites. Therefore, the gut microbiome and its interaction with the host influences many aspects of health and disease, including the composition of biofluids such as urine and blood plasma. Metabolomics is uniquely suited to capture these functional host-microbe interactions. This review aims at providing an overview of recent metabolomics evidence of gut microbiota-host metabolic interactions with a specific focus on cardiovascular disease and related aspects of the metabolic syndrome. Furthermore, the emphasis is given on the complexities of translating these metabolite signatures as potential clinical biomarkers, as the composition and activity of gut microbiome change with many factors, particularly with diet, with special reference to trimethylamine-oxide.

Altered intestinal microbial flora and impaired epithelial barrier structure and function in CKD: the nature, mechanisms, consequences and potential treatment

Chronic kidney disease (CKD) results in systemic inflammation and oxidative stress which play a central role in CKD progression and its adverse consequences. Although many of the causes and consequences of oxidative stress and inflammation in CKD have been extensively explored, little attention had been paid to the intestine and its microbial flora as a potential source of these problems. Our recent studies have revealed significant disruption of the colonic, ileal, jejunal and gastric epithelial tight junction in different models of CKD in rats. Moreover, the disruption of the epithelial barrier structure and function found in uremic animals was replicated in cultured human colonocytes exposed to uremic human plasma in vitro We have further found significant changes in the composition and function of colonic bacterial flora in humans and animals with advanced CKD. Together, uremia-induced impairment of the intestinal epithelial barrier structure and function and changes in composition of the gut microbiome contribute to the systemic inflammation and uremic toxicity by accommodating the translocation of endotoxin, microbial fragments and other noxious luminal products in the circulation. In addition, colonic bacteria are the main source of several well-known pro-inflammatory uremic toxins such as indoxyl sulfate, p-cresol sulfate, trimethylamine-N-oxide and many as-yet unidentified retained compounds in end-stage renal disease patients. This review is intended to provide an overview of the effects of CKD on the gut microbiome and intestinal epithelial barrier structure and their role in the pathogenesis of systemic inflammation and uremic toxicity. In addition, potential interventions aimed at mitigating these abnormalities are briefly discussed.

Role of altered intestinal microbiota in systemic inflammation and cardiovascular disease in chronic kidney disease

The normal intestinal microbiota plays a major role in the maintenance of health and disease prevention. In fact, the alteration of the intestinal microbiota has been shown to contribute to the pathogenesis of several pathological conditions, including obesity and insulin resistance, among others. Recent studies have revealed profound alterations of the gut microbial flora in patients and animals with chronic kidney disease (CKD). Alterations in the composition of the microbiome in CKD may contribute to the systemic inflammation and accumulation of gut-derived uremic toxins, which play a central role in the pathogenesis of accelerated cardiovascular disease and numerous other CKD-associated complications. This review is intended to provide a concise description of the potential role of the CKD-associated changes in the gut microbiome and its potential role the pathogenesis of inflammation and uremic toxicity. In addition, the potential efficacy of pre- and pro-biotics in the restoration of the microbiome is briefly described.

Myricetin derived from Hovenia dulcis Thunb. ameliorates vascular endothelial dysfunction and liver injury in high choline-fed mice

The present study was conducted to explore the protective effects of myricetin (MYR) purified from Hovenia dulcis Thunb. against vascular endothelial dysfunction and liver injury in mice fed with 3% dietary choline water.

Egg consumption and risk of cardiovascular diseases and diabetes: a meta-analysis

OBJECTIVES

To assess the dose-response relationship between egg consumption and the risk of cardiovascular diseases (CVD) and diabetes.

METHODS

We systematically searched MEDLINE database through December 2012. Fixed- or random-effects model was used to pool the relative risks (RRs) and their 95% confidence intervals (CIs). Subgroup analyses was performed to explore the potential sources of heterogeneity. Weighted linear regression model was used to estimate the dose-response relationship.

RESULTS

Fourteen studies involving 320,778 subjects were included. The pooled RRs of the risk of CVD, CVD for separated diabetes patients, and diabetes for the highest vs lowest egg intake were 1.19 (95% CI 1.02-1.38), 1.83 (95% CI 1.42-2.37), 1.68 (95% CI 1.41-2.00), respectively. For each 4/week increment in egg intake, the RRs of the risk for CVD, CVD for separated diabetes patients, diabetes was 1.06 (95% CI 1.03-1.10), 1.40 (95% CI 1.25-1.57), 1.29 (95% CI 1.21-1.37), respectively. Subgroup analyses showed that population in other western countries have increased CVD than ones in USA (RR 2.00, 95% CI 1.14 to 3.51 vs 1.13, 95% CI 0.98 to 1.30, P = 0.02 for subgroup difference).

CONCLUSIONS

Our study suggests that there is a dose-response positive association between egg consumption and the risk of CVD and diabetes.

Man and his spaceships: Vehicles for extraterrestrial colonization?

The resiliency and adaptive ability of microbial life in real time on Earth relies heavily upon horizontal gene transfer. Based on that knowledge, how likely is earth based microbial life to colonize extraterrestrial targets such as Mars? To address this question, we consider manned and unmanned space exploration, the resident microbiota that is likely to inhabit those vehicles, the adaptive potential of that microbiota in an extraterrestrial setting especially with regards to mobile genetic elements, and the likelihood that Mars like environments could initiate and sustain colonization.

The Use of High-Throughput Technologies to Investigate Vascular Inflammation and Atherosclerosis

The greatest challenge of scientific research is to understand the causes and consequences of disease. In recent years, great efforts have been devoted to unraveling the basic mechanisms of atherosclerosis (the underlying pathology of cardiovascular disease), which remains a major cause of morbidity and mortality worldwide. Because of the complex and multifactorial pathophysiology of cardiovascular disease, different research techniques have increasingly been combined to unravel genetic aspects, molecular pathways, and cellular functions involved in atherogenesis, vascular inflammation, and dyslipidemia to gain a multifaceted picture addressing this complexity. Thanks to the rapid evolution of high-throughput technologies, we are now able to generate large-scale data on the DNA, RNA, and protein levels. With the help of sophisticated computational tools, these data sets are integrated to enhance information extraction and are being increasingly used in a systems biology approach to model biological processes as interconnected and regulated networks. This review exemplifies the use of high-throughput technologies—such as genomics, transcriptomics, proteomics, and epigenomics—and systems biology to explore pathomechanisms of vascular inflammation and atherosclerosis.

Choline supplementation and measures of choline and betaine status: a randomised, controlled trial in postmenopausal women

Choline is an essential nutrient and can also be obtained by de novo synthesis via an oestrogen responsive pathway. Choline can be oxidised to the methyl donor betaine, with short-term supplementation reported to lower plasma total homocysteine (tHcy); however, the effects of longer-term choline supplementation are less clear. We investigated the effect of choline supplementation on plasma concentrations of free choline, betaine and tHcy and B-vitamin status in postmenopausal women, a group more susceptible to low choline status. We also assessed whether supplementation altered plasma lipid profiles. In this randomised, double-blinded, placebo-controlled study, forty-two healthy postmenopausal women received 1 g choline per d (as choline bitartrate), or an identical placebo supplement with their habitual diet. Fasting blood samples were collected at baseline, week 6 and week 12. Administration of choline increased median choline and betaine concentrations in plasma, with significant effects evident after 6 weeks of supplementation (P<0·001) and remaining significant at 12 weeks (P<0·001); no effect was observed on folate status or on plasma lipids. Choline supplementation induced a median (25th, 75th percentile) change in plasma tHcy concentration at week 6 of -0·9 (-1·6, 0·2) μmol, a change which, when compared to that observed in the placebo group 0·6 (-0·4, 1·9) μmol, approached statistical significance (P=0·058). Choline supplementation at a dose of 1 g/d significantly increases the circulating concentration of free choline, and can also significantly increase the concentration of the methyl donor, betaine, thereby potentially enhancing the betaine-homocysteine methyltransferase-mediated remethylation of tHcy.