Manipulation of the gut microbiota by the use of prebiotic fibre does not override a genetic predisposition to heart failure

Gut Microbiota in Heart Failure-The Role of Inflammation

Heart failure (HF) has become an immense health concern affecting almost 1-2% of the population globally. It is a complex syndrome characterized by activation of the sympathetic nervous system and the Renin-Angiotensin-Aldosterone (RAAS) axis as well as endothelial dysfunction, oxidative stress, and inflammation. The recent literature points towards the interaction between the intestinal flora and the heart, also called the gut-heart axis. The human gastrointestinal tract is naturally inhabited by various microbes, which are distinct for each patient, regulating the functions of many organs. Alterations of the gut microbiome, a process called dysbiosis, may result in systemic diseases and have been associated with heart failure through inflammatory and autoimmune mechanisms. The disorder of intestinal permeability favors the translocation of microbes and many metabolites capable of inducing inflammation, thus further contributing to the deterioration of normal cardiac function. Besides diet modifications and exercise training, many studies have revealed possible gut microbiota targeted treatments for managing heart failure. The aim of this review is to demonstrate the impact of the inflammatory environment induced by the gut microbiome and its metabolites on heart failure and the elucidation of these novel therapeutic approaches.

Gut Microbiota and Gut-Brain Axis in Hypertension: Implications for Kidney and Cardiovascular Health-A Narrative Review

INTRODUCTION

Arterial hypertension is a major contributor to a wide range of health complications, with cardiac hypertrophy and chronic kidney disease being among the most prevalent. Consequently, novel strategies for the treatment and prevention of hypertension are actively being explored. Recent research has highlighted a potential link between hypertension and the gut-brain axis. A bidirectional communication between the microbiota and the brain via the vagus nerve, enteric nervous system, hypothalamus-pituitary-adrenal axis, secreted short-chain fatty acids, and neurotransmitter metabolism.

MATERIALS AND METHODS

A comprehensive literature search was conducted using databases such as PubMed to identify studies exploring the relationship between gut microbiota and hypertension, along with the effects of dietary interventions and probiotics on blood pressure regulation.

DISCUSSION

Studies in both animal models and human subjects have demonstrated a strong correlation between alterations in gut microbiota composition and the development of hypertension. By influencing blood pressure, the gut microbiota can potentially affect the progression of cardiovascular and kidney disorders. Modulating gut microbiota through dietary interventions and probiotics has shown promise in regulating blood pressure and reducing systemic inflammation, offering a novel approach to managing hypertension. Diets such as the Mediterranean diet, which is rich in polyphenols and omega-3 fatty acids and low in sodium, promote the growth of beneficial gut bacteria that support cardiovascular health. Additionally, probiotics have been found to enhance gut barrier function, reduce inflammation, and modulate the Renin-Angiotensin System, all of which contribute to lowering blood pressure.

CONCLUSIONS

Further research is needed to determine the mechanisms of action of the microbiota in hypertension. The aim of this study was to evaluate the influence of gut microbiota on blood pressure regulation and the progression of hypertension-related complications, such as cardiovascular and kidney disorders.

Heart Failure: a Punch from the Gut

PURPOSE OF REVIEW

This article seeks to elucidate the mechanisms underlying the bidirectional relationship between the gut and the heart, focusing on the pathophysiology of heart failure. We have previously demonstrated that Heart failure (HF) has significant effects on splanchnic vasculature and leads to key alterations in the gut microbiome, portending greater comorbidity with HF.

RECENT FINDINGS

A growing field of research is focused on the effects of a "leaky gut" in the development of disease across organ systems. The leaky gut hypothesis centers on intestinal epithelial barrier dysfunction causing increased permeability of the gut and subsequent alterations to gut composition by endotoxins and microbial metabolites. Changes in the quantities of metabolites including short-chain fatty acids, trimethylamine N-oxide and other amino acid metabolites, and various bile acid species have been shown to result in gut dysbiosis and worsening HF. The gut plays a highly significant role in HF prognosis and requires greater attention for future therapeutic interventions. Treatments targeting gut composition could have very beneficial effects on HF prognosis.

Dietary Fiber and Microbiota Metabolite Receptors Enhance Cognition and Alleviate Disease in the 5xFAD Mouse Model of Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative disorder with poorly understood etiology. AD has several similarities with other "Western lifestyle" inflammatory diseases, where the gut microbiome and immune pathways have been associated. Previously, we and others have noted the involvement of metabolite-sensing GPCRs and their ligands, short-chain fatty acids (SCFAs), in protection of numerous Western diseases in mouse models, such as Type I diabetes and hypertension. Depletion of GPR43, GPR41, or GPR109A accelerates disease, whereas high SCFA yielding diets protect in mouse models. Here, we extended the concept that metabolite-sensing receptors and SCFAs may be a more common protective mechanism against Western diseases by studying their role in AD pathogenesis in the 5xFAD mouse model. Both male and female mice were included. Depletion of GPR41 and GPR43 accelerated cognitive decline and impaired adult hippocampal neurogenesis in 5xFAD and WT mice. Lack of fiber/SCFAs accelerated a memory deficit, whereas diets supplemented with high acetate and butyrate (HAMSAB) delayed cognitive decline in 5xFAD mice. Fiber intake impacted on microglial morphology in WT mice and microglial clustering phenotype in 5xFAD mice. Lack of fiber impaired adult hippocampal neurogenesis in both W and AD mice. Finally, maternal dietary fiber intake significantly affects offspring's cognitive functions in 5xFAD mice and microglial transcriptome in both WT and 5xFAD mice, suggesting that SCFAs may exert their effect during pregnancy and lactation. Together, metabolite-sensing GPCRs and SCFAs are essential for protection against AD, and reveal a new strategy for disease prevention.Significance Statement Alzheimer's disease (AD) is one of the most common neurodegenerative diseases; currently, there is no cure for AD. In our study, short-chain fatty acids and metabolite receptors play an important role in cognitive function and pathology in AD mouse model as well as in WT mice. SCFAs also impact on microglia transcriptome, and immune cell recruitment. Out study indicates the potential of specialized diets (supplemented with high acetate and butyrate) releasing high amounts of SCFAs to protect against disease.

Impact of Diet on Gut Microbiota Composition and Microbiota-Associated Functions in Heart Failure: A Systematic Review of In Vivo Animal Studies

Heart failure (HF) represents a cardiovascular disease with high mortality and morbidity. The latest evidence shows that changes in the composition of the gut microbiota might play a pivotal role in the prevention and management of HF. This systematic review aims at assessing the potential associations between the diet, gut microbiota, and derived metabolites with the outcomes of HF. A systematic literature search was performed up to July 2022 on the PubMed, Web of Science, and Scopus databases. The PRISMA guidelines were followed when possible. The risk of bias was assessed with the SYRCLE and ARRIVE tools. A total of nine pre-clinical studies on animal models, with considerable heterogeneity in dietary interventions, were included. High-fiber/prebiotic diets (n = 4) and a diet rich in polyphenols (n = 1) modified the gut microbiota composition and increased microbial metabolites' activities, linked with an improvement in HF outcomes, such as a reduction in systolic blood pressure, cardiac hypertrophy, and left ventricular thickness. A high-fat diet (n = 2) or a diet rich in choline (n = 2) induced an increase in TMAO and indole derivative production associated with a decrease in cardiac function, systemic endotoxemia, and inflammation and an increase in cardiac fibrosis and cardiac remodeling. Although results are retrieved from animal studies, this systematic review shows the key role of the diet-especially a high-fiber and prebiotic diet-on gut microbial metabolites in improving HF outcomes. Further studies on human cohorts are needed to identify personalized therapeutic dietary interventions to improve cardiometabolic health.

Short-Chain Fatty Acids in Gut-Heart Axis: Their Role in the Pathology of Heart Failure

Heart failure (HF) is a syndrome with global clinical and socioeconomic burden worldwide owing to its poor prognosis. Accumulating evidence has implicated the possible contribution of gut microbiota-derived metabolites, short-chain fatty acids (SCFAs), on the pathology of a variety of diseases. The changes of SCFA concentration were reported to be observed in various cardiovascular diseases including HF in experimental animals and humans. HF causes hypoperfusion and/or congestion in the gut, which may lead to lowered production of SCFAs, possibly through the pathological changes of the gut microenvironment including microbiota composition. Recent studies suggest that SCFAs may play a significant role in the pathology of HF, possibly through an agonistic effect on G-protein-coupled receptors, histone deacetylases (HDACs) inhibition, restoration of mitochondrial function, amelioration of cardiac inflammatory response, its utilization as an energy source, and remote effect attributable to a protective effect on the other organs. Collectively, in the pathology of HF, SCFAs might play a significant role as a key mediator in the gut-heart axis. However, these possible mechanisms have not been entirely clarified and need further investigation.

Microbial metabolites and heart failure: Friends or enemies?

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

Integrated omics analysis: the relationship between significantly increased Klebsiella post-hepatectomy and decreased hub-metabolite 3-methyl-2-oxobutanoic acid is associated with induced liver failure

BACKGROUND

This study sought to evaluate the association between intestinal Klebsiella and post-hepatectomy liver failure (PHLF) in patients with hepatitis B virus (HBV)-related hepatocellular carcinoma (B-HCC), and identify the inner relationship.

METHODS

Patients with B-HCC were divided into Groups A and B based on the presence or absence of PHLF. 16S ribosomal ribonucleic acid surveys were used to identify gut microbiome alterations. PICRUST2 was used to examine the metagenomic data in PHLF patients. Fecal and serum samples were processed by chromatography-mass spectrometry based non-targeted metabonomics, then comprehensively analyzed to obtain hub metabolites. A Spearman correlation analysis was then conducted to find any associations between fecal differential metabolites and the relative abundance of differential microbes.

RESULTS

Hepatectomies were significantly associated with a gut microbial imbalance in B-HCC patients, and a significant elevation of Klebsiella abundance was observed in PHLF patients. Klebsiella appears to act on 13 amino acid-related pathways, especially significantly observed in branched-chain amino acid (BCAA) metabolic pathways. Additionally, Klebsiella was found to be highly correlated with 3-methyl-2-oxobutanoic acid shared by feces and serum in the BCAA metabolic pathway.

CONCLUSIONS

Hepatectomy can lead to an imbalance of intestinal microflora in B-HCC patients. Due to its potential connections with 3-methyl-2-oxobutanoic acid in the BCAA pathway, significantly increased Klebsiella has the potential to be an evaluation indicator of PHLF in B-HCC patients. Moreover, 3-methyl-2-oxobutanoic acid has research value in PHLF-targeted treatments.