Uncovering the Role of Gut Microbiota in Amino Acid Metabolic Disturbances in Heart Failure Through Metagenomic Analysis

The use of an in vitro fecal fermentation model to uncover the beneficial role of omega-3 and punicic acid in gut microbiota alterations induced by a Western diet

The influence of gut microbiota in the onset and development of several metabolic diseases has gained attention over the last few years. Diet plays an essential role in gut microbiota modulation. Western diet (WD), characterized by high-sugar and high-fat consumption, alters gut microbiome composition, diversity index, microbial relative levels, and functional pathways. Despite the promising health effects demonstrated by polyunsaturated fatty acids, their impact on gut microbiota is still overlooked. The effect of Fish oil (omega-3 source) and Pomegranate oil (punicic acid source), and a mixture of both oils in gut microbiota modulation were determined by subjecting the oil samples to in vitro fecal fermentations. Cecal samples from rats from two different dietary groups: a control diet (CD) and a high-fat high-sugar diet (WD), were used as fecal inoculum. 16S amplicon metagenomics sequencing showed that Fish oil + Pomegranate oil from the WD group increased α-diversity. This sample can also increase the relative abundance of the Firmicutes and Bacteroidetes phylum as well as Akkermansia and Blautia, which were affected by the WD consumption. All samples were able to increase butyrate and acetate concentration in the WD group. Moreover, tyrosine concentrations, a precursor for dopamine and norepinephrine, increase in the Fish oil + Pomegranate oil WD sample. GABA, an important neurotransmitter, was also increased in WD samples. These results suggest a potential positive impact of these oils' mixture on gut-brain axis modulation. It was demonstrated, for the first time, the great potential of using a mixture of both Fish and Pomegranate oil to restore the gut microbiota changes associated with WD consumption.

The Role of Gut Microbiota and Its Metabolites in Patients with Heart Failure

Heart failure (HF) is a significant health concern; early detection and prevention are crucial. Recent studies suggest that the gut microbiota and its metabolites may influence HF development and risk factors. We explored this relationship by examining changes in gut microbiota composition and metabolite levels in HF patients. HF patients often exhibit decreased alpha and beta diversity compared to controls, suggesting lower bacterial richness and community variation. Changes in specific bacterial phyla were observed, with decreases in Firmicutes (e.g., Ruminococcus) and Bacteroidetes (e.g., Prevotella) and increases in Proteobacteria (e.g., Escherichia, Shigella, and Klebsiella) and Actinobacteria. Gut-microbiota-related metabolites have been identified, potentially affecting various body systems, including the cardiovascular system. Among these are short-chain fatty acids (SCFAs), betaine, trimethylamine N-oxide (TMAO), phenylalanine, tryptophan-kynurenine, and phenylacetylgutamine (PAGIn). Although SCFAs positively affect our organisms, patients with HF have been observed to experience a decline in bacteria responsible for producing these chemical compounds. There have been indications of possible links between betaine, TMAO, phenylalanine, tryptophan-kynurenine, PAGIn, and heart failure. TMAO and phenylalanine, in particular, show promise as potential prognostic factors. However, their clinical significance has not yet been thoroughly evaluated and requires further investigation.

NAD metabolic therapy in metabolic dysfunction-associated steatotic liver disease: Possible roles of gut microbiota

Metabolic dysfunction-associated steatotic liver disease (MASLD), formerly named non-alcoholic fatty liver disease (NAFLD), is induced by alterations of hepatic metabolism. As a critical metabolites function regulator, nicotinamide adenine dinucleotide (NAD) nowadays has been validated to be effective in the treatment of diet-induced murine model of MASLD. Additionally, gut microbiota has been reported to have the potential to prevent MASLD by dietary NAD precursors metabolizing together with mammals. However, the underlying mechanism remains unclear. In this review, we hypothesized that NAD enhancing mitochondrial activity might reshape a specific microbiota signature, and improve MASLD progression demonstrated by fecal microbiota transplantation. Here, this review especially focused on the mechanism of Microbiota-Gut-Liver Axis together with NAD metabolism for the MASLD progress. Notably, we found significant changes in Prevotella associated with NAD in a gut microbiome signature of certain MASLD patients. With the recent researches, we also inferred that Prevotella can not only regulate the level of NAD pool by boosting the carbon metabolism, but also play a vital part in regulating the branched-chain amino acid (BCAA)-related fatty acid metabolism pathway. Altogether, our results support the notion that the gut microbiota contribute to the dietary NAD precursors metabolism in MASLD development and the dietary NAD precursors together with certain gut microbiota may be a preventive or therapeutic strategy in MASLD management.

Comparative profiling of gut microbiota and metabolome in diet-induced obese and insulin-resistant C57BL/6J mice

Diet-based models are commonly used to investigate obesity and related disorders. We conducted a comparative profiling of three obesogenic diets HFD, high fat diet; HFHF, high fat high fructose diet; and HFCD, high fat choline deficient diet to assess their impact on the gut microbiome and metabolome. After 20 weeks, we analyzed the gut microbiota and metabolomes of liver, plasma, cecal, and fecal samples. Fecal and plasma bile acids (BAs) and fecal short-chain fatty acids (SCFAs) were also examined. Significant changes were observed in fecal and cecal metabolites, with increased Firmicutes and decreased Bacteroidetes in the HFD, HFHF, and HFCD-fed mice compared to chow and LFD (low fat diet)-fed mice. Most BAs were reduced in plasma and fecal samples of obese groups, except taurocholic acid, which increased in HFCD mice's plasma. SCFAs like acetate and butyrate significantly decreased in obesogenic diet groups, while propionic acid specifically decreased in the HFCD group. Pathway analysis revealed significant alterations in amino acid, carbohydrate metabolism, and nucleic acid biosynthesis pathways in obese mice. Surprisingly, even LFD-fed mice showed distinct changes in microbiome and metabolite profiles compared to the chow group. This study provides insights into gut microbiome dysbiosis and metabolite alterations induced by obesogenic and LFD diets in various tissues. These findings aid in selecting suitable diet models to study the role of the gut microbiome and metabolites in obesity and associated disorders, with potential implications for understanding similar pathologies in humans.

Breaking the barriers: the role of gut homeostasis in Metabolic-Associated Steatotic Liver Disease (MASLD)

Obesity, insulin resistance (IR), and the gut microbiome intricately interplay in Metabolic-associated Steatotic Liver Disease (MASLD), previously known as Non-Alcoholic Fatty Liver Disease (NAFLD), a growing health concern. The complex progression of MASLD extends beyond the liver, driven by "gut-liver axis," where diet, genetics, and gut-liver interactions influence disease development. The pathophysiology of MASLD involves excessive liver fat accumulation, hepatocyte dysfunction, inflammation, and fibrosis, with subsequent risk of hepatocellular carcinoma (HCC). The gut, a tripartite barrier, with mechanical, immune, and microbial components, engages in a constant communication with the liver. Recent evidence links dysbiosis and disrupted barriers to systemic inflammation and disease progression. Toll-like receptors (TLRs) mediate immunological crosstalk between the gut and liver, recognizing microbial structures and triggering immune responses. The "multiple hit model" of MASLD development involves factors like fat accumulation, insulin resistance, gut dysbiosis, and genetics/environmental elements disrupting the gut-liver axis, leading to impaired intestinal barrier function and increased gut permeability. Clinical management strategies encompass dietary interventions, physical exercise, pharmacotherapy targeting bile acid (BA) metabolism, and microbiome modulation approaches through prebiotics, probiotics, symbiotics, and fecal microbiota transplantation (FMT). This review underscores the complex interactions between diet, metabolism, microbiome, and their impact on MASLD pathophysiology and therapeutic prospects.

Potential therapeutic implications of histidine catabolism by the gut microbiota in NAFLD patients with morbid obesity

The gut microbiota contributes to the pathophysiology of non-alcoholic fatty liver disease (NAFLD). Histidine is a key energy source for the microbiota, scavenging it from the host. Its role in NAFLD is poorly known. Plasma metabolomics, liver transcriptomics, and fecal metagenomics were performed in three human cohorts coupled with hepatocyte, rodent, and Drosophila models. Machine learning analyses identified plasma histidine as being strongly inversely associated with steatosis and linked to a hepatic transcriptomic signature involved in insulin signaling, inflammation, and trace amine-associated receptor 1. Circulating histidine was inversely associated with Proteobacteria and positively with bacteria lacking the histidine utilization (Hut) system. Histidine supplementation improved NAFLD in different animal models (diet-induced NAFLD in mouse and flies, ob/ob mouse, and ovariectomized rats) and reduced de novo lipogenesis. Fecal microbiota transplantation (FMT) from low-histidine donors and mono-colonization of germ-free flies with Enterobacter cloacae increased triglyceride accumulation and reduced histidine content. The interplay among microbiota, histidine catabolism, and NAFLD opens therapeutic opportunities.

Gut-Kidney-Heart: A Novel Trilogy

The microbiota represents a key factor in determining health and disease. Its role in inflammation and immunological disorders is well known, but it is also involved in several complex conditions, ranging from neurological to psychiatric, from gastrointestinal to cardiovascular diseases. It has recently been hypothesized that the gut microbiota may act as an intermediary in the close interaction between kidneys and the cardiovascular system, leading to the conceptualization of the "gut-kidney-heart" axis. In this narrative review, we will discuss the impact of the gut microbiota on each system while also reviewing the available data regarding the axis itself. We will also describe the role of gut metabolites in this complex interplay, as well as potential therapeutical perspectives.

Dapagliflozin-affected endothelial dysfunction and altered gut microbiota in mice with heart failure

Aim

To investigate the potential microbiome profile of a mouse model with heart failure (HF) during dapagliflozin treatment.

Method

An HF model was constructed in 8-week-old male mice, and cardiac tissues were analyzed using histological staining. Hemodynamic indexes were measured, and fecal samples were collected for 16S rDNA sequencing. Chao1, Shannon, and Simpson were used for α-diversity analysis. b-Diversity analysis was conducted using principal coordinate analysis (PCoA) and non-metric multidimensional scaling (NMDS) based on the Bray-Curtis distance. Linear discriminant analysis coupled with effect size measurements (LEfSe) was used to identify signature gut microbiota, and phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt) was used to predict the function of altered gut microbiota.

Result

Dapagliflozin treatment reduced inflammation, infarction area, and cardiac fibrosis in HF mice. It also increased endothelial-dependent dilation and inflammation in mice with HF. Dapagliflozin decreased the ratio of Firmicutes/Bacteroidetes, which was increased in HF mice. There was no significant statistical difference in α-diversity among the control, HF, and HF+dapagliflozin groups. Desulfovibrio, AF12, and Paraprevotella were enriched in HF+dapagliflozin, while Rikenella and Mucispirillum were enriched in HF based on LEfSe. KEGG analysis revealed that altered gut microbiota was associated with fermentation, amino acid biosynthesis, nucleoside and nucleotide biosynthesis/degradation, fatty acid and lipid biosynthesis, carbohydrate biosynthesis/degradation, and cofactor/prosthetic group/electron carrier/vitamin biosynthesis.

Conclusion

Understanding the microbiome profile helps elucidate the mechanism of dapagliflozin for HF. The signature genera identified in this study could be used as a convenient method to distinguish between HF patients and healthy individuals.

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.

Pain sensation and gut microbiota profiles in older adults with heart failure

Objectives

Patients with heart failure (HF) experience severe pain and may have altered pain sensation; however, the underlying mechanisms of these symptoms are not yet fully understood. Identifying pain sensation and genomic biomarkers of pain in older adults with HF is a critical step toward developing personalized interventions to improve pain management and outcomes. This study aimed to investigate the differences in pain sensation, gut microbiota, self-reported pain, and symptoms in older adults with and without HF.

Methods

Twenty older adults with HF and age-matched healthy controls (HCs) were recruited in the Northeastern United States. Quantitative sensory testing and conditioned pain modulation were performed on the nondominant upper arm to detect the mechanical, thermal, and pressure pain thresholds and pain modulations. Stool samples were collected, and the 16S rRNA V4 gene region of stool samples was sequenced and processed using the Mothur 1.42.3 pipeline. Self-reported pain and symptoms were measured by the Brief Pain Inventory and the NIH Patient-reported Outcomes Measurement Information System. The associations between pain sensation, gut microbiota α-diversity indices, and pain and symptoms were explored using the Spearman correlations.

Results

The HF and HC subjects' mean ages were 73.50 (SD = 8.33) and 67.10 (SD = 7.64), respectively. The HF subjects reported significantly higher pain intensity and interference, sleep disturbance, fatigue, anxiety, and depression than the HCs. The HF subjects also had a significantly lower level of physical function and participation in social roles and activities. Compared with the HCs, the HF subjects had significantly altered conditioned pain modulation heat effect and gut microbiota compositions and predicted metabolic functions. The Statistical Analysis Of Metagenomic Profiles indicated that the HF subjects had a significantly decreased cardiac muscle contraction pathway compared with the HCs. The correlation analysis showed that the quantitative sensory testing profiles and gut microbiota diversity index were significantly associated with pain and symptoms in older adults with HF.

Conclusions

Older adults with HF had more severe self-reported pain and symptoms, altered pain sensation, and different gut microbiota composition and function compared with age-matched HCs. Pain sensation and gut microbiota may contribute to pain and symptoms in older adults with HF and could serve as biomarkers of pain and symptoms of HF. Further research with a larger sample size is warranted to confirm these findings.

The Implication of the Gut Microbiome in Heart Failure

Heart failure is a worldwide health problem with important consequences for the overall wellbeing of affected individuals as well as for the healthcare system. Over recent decades, numerous pieces of evidence have demonstrated that the associated gut microbiota represent an important component of human physiology and metabolic homeostasis, and can affect one's state of health or disease directly, or through their derived metabolites. The recent advances in human microbiome studies shed light on the relationship between the gut microbiota and the cardiovascular system, revealing its contribution to the development of heart failure-associated dysbiosis. HF has been linked to gut dysbiosis, low bacterial diversity, intestinal overgrowth of potentially pathogenic bacteria and a decrease in short chain fatty acids-producing bacteria. An increased intestinal permeability allowing microbial translocation and the passage of bacterial-derived metabolites into the bloodstream is associated with HF progression. A more insightful understanding of the interactions between the human gut microbiome, HF and the associated risk factors is mandatory for optimizing therapeutic strategies based on microbiota modulation and offering individualized treatment. The purpose of this review is to summarize the available data regarding the influence of gut bacterial communities and their derived metabolites on HF, in order to obtain a better understanding of this multi-layered complex relationship.

Re-defining the Gut Heart Axis: A Systematic Review of the Literature on the Role of Gut Microbial Dysbiosis in Patients With Heart Failure

Heart failure (HF) contributes to the cardiovascular health burden worldwide. Patients with heart failure have been recently studied to possess unique changes in the gut microbiome that affect immune homeostasis and metabolism. In this systematic review of the literature, we aim to identify the impact of gut dysbiosis on heart failure. We used Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines to conduct our systematic review. We searched the literature on databases such as PubMed, PubMed Central (PMC), Medline, and ScienceDirect. Ten articles were included for review. There were significant differences in the gut microbiome composition in heart failure. Relative abundance of Ruminococcus gnavus, Escherichia Shigella, Streptococcus sp, Veillonella sp, and Actinobacteria, and relative depletion of Eubacterium, Prevotella, Faecalibacterium, SMB53, and Megamonas. The composition varied according to age, heart failure stage, and decompensation level. The composition remained unaltered with ejection fraction. There was an increased expression of genes responsible for the metabolism of amino acids, carbohydrates, choline trimethylamine-lyase (TMA-lyase), lipopolysaccharide (LPS) biosynthesis, tryptophan, and lipid metabolism. The resultant changes affected the levels of metabolites, such as trimethylamine N-oxide (TMAO), indoxyl sulfate (IS), and LPS, and inflammatory markers in the feces and plasma, which contributed to heart failure. These biomarkers of heart failure could serve as targets for the prevention and treatment of heart failure. Patients with heart failure harbor a unique constellation of gut microbiota that affect the pathogenesis of heart failure. Further studies are needed to understand the causal relationship between dysbiosis and heart failure.

Dapagliflozin modulates the faecal microbiota after myocardial infarction in non-diabetic mice

The gut microbiota seems to be a major modulator of cardiovascular diseases, such as myocardial infarction. Dapagliflozin, a sodium glucose cotransporter 2 inhibitor (SGLT2i), is an antidiabetic agent that was recently utilized in patients with cardiovascular diseases. This study aims to investigate the effects of dapagliflozin on the faecal microbiota of postinfarction non-diabetic mice. A total of 19 male mice were randomly divided into three groups, where two groups were enduced with myocardial infarction (MI) by left anterior descending ligation. One day after the surgery, each group was administered normal saline (15 mL/kg/day, 0.9%) or dapagliflozin (1.5 mg/kg/day) for 4 weeks. Echocardiography was obtained on day 28 post MI. Masson's trichrome staining was used to determine the degree of fibrosis. Faecal samples were collected to assess the microbiome by 16S ribosomal RNA gene sequencing. We found that dapagliflozin significantly improved cardiac function in the non-diabetic myocardial infarction mice model after the 28-day treatment, especially in ejection fraction and fractional shortening (p < 0.01). Enterotypes were composed of Muribaculaceae and Lactobacillaceae after dapagliflozin treatment, while Muribaculaceae and Erysipelotrichaceae were the main enterotypes post-MI. Dapagliflozin increased the abundance of beneficial bacteria like Lactobacillaceae, while decreasing the abundance of beneficial bacteria like Bifidobacteriaceae. It was interesting to discover that Proteobacteria (especially Desulfovibrionaceae) were enriched after the dapagliflozin treatment for myocardial infarction. Dapagliflozin increased the abundance of the main beneficial bacteria. In post-myocardial infarction treatments, using dapagliflozin could positively contribute to the improvement of cardiac function and alter the structure of faecal microbiota.

Local and systemic effects of microbiome‐derived metabolites

Commensal microbes form distinct ecosystems within their mammalian hosts, collectively termed microbiomes. These indigenous microbial communities broadly expand the genomic and functional repertoire of their host and contribute to the formation of a “meta‐organism.” Importantly, microbiomes exert numerous biochemical reactions synthesizing or modifying multiple bioactive small molecules termed metabolites, which impact their host's physiology in a variety of contexts. Identifying and understanding molecular mechanisms of metabolite–host interactions, and how their disrupted signaling can contribute to diseases, may enable their therapeutic application, a modality termed “postbiotic” therapy. In this review, we highlight key examples of effects of bioactive microbe‐associated metabolites on local, systemic, and immune environments, and discuss how these may impact mammalian physiology and associated disorders. We outline the challenges and perspectives in understanding the potential activity and function of this plethora of microbially associated small molecules as well as possibilities to harness them toward the promotion of personalized precision therapeutic interventions.

Psoriasis: Interplay between dysbiosis and host immune system

With advancement in human microbiome research, an increasing number of scientific evidences have endorsed the key role of both gut and skin microbiota in the pathogenesis of psoriasis. Microbiome dysbiosis, characterized by altered diversity and composition, as well as rise of pathobionts, have been identified as possible triggers for recurrent episodes of psoriasis. Mechanistically, gut dysbiosis leads to "leaky gut syndrome" via disruption of epithelial bilayer, thereby, resulting in translocation of bacteria and other endotoxins to systemic circulation, which in turn, results in inflammatory response. Similarly, skin dysbiosis disrupts the cutaneous homeostasis, leading to invasion of bacteria and other pathogens to deeper layers of skin or even systemic circulation further enhanced by injury caused by pruritus-induced scratching, and elicit innate and adaptive inflammation. The present review explores the correlation of both skin and gut microbiota dysbiosis with psoriasis. Also, the studies highlighting the potential of bacteriotherapeutic approaches including probiotics, prebiotics, metabiotics, and fecal microbiota transplantation for the management of psoriasis have been discussed.

The Role of Branched-Chain Amino Acids and Branched-Chain α-Keto Acid Dehydrogenase Kinase in Metabolic Disorders

Branched-chain amino acids (BCAAs), composed of leucine, isoleucine, and valine, are important essential amino acids in human physiology. Decades of studies have revealed their roles in protein synthesis, regulating neurotransmitter synthesis, and the mechanistic target of rapamycin (mTOR). BCAAs are found to be related to many metabolic disorders, such as insulin resistance, obesity, and heart failure. Also, many diseases are related to the alteration of the BCAA catabolism enzyme branched-chain α-keto acid dehydrogenase kinase (BCKDK), including maple syrup urine disease, human autism with epilepsy, and so on. In this review, diseases and the corresponding therapies are discussed after the introduction of the catabolism and detection methods of BCAAs and BCKDK. Also, the interaction between microbiota and BCAAs is highlighted.

Heart Failure Severity Closely Correlates with Intestinal Dysbiosis and Subsequent Metabolomic Alterations

Growing evidence suggests an altered gut microbiome in patients with heart failure (HF). However, the exact interrelationship between microbiota, HF, and its consequences on the metabolome are still unknown. We thus aimed here to decipher the association between the severity and progression of HF and the gut microbiome composition and circulating metabolites. Using a mouse model of transverse aortic constriction (TAC), gut bacterial diversity was found to be significantly lower in mice as early as day 7 post-TAC compared to Sham controls (p = 0.03), with a gradual progressive decrease in alpha-diversity on days 7, 14, and 42 (p = 0.014, p = 0.0016, p = 0.0021) compared to day 0, which coincided with compensated hypertrophy, maladaptive hypertrophy, and overtly failing hearts, respectively. Strikingly, segregated analysis based on the severity of the cardiac dysfunction (EF < 40% vs. EF 40−55%) manifested marked differences in the abundance and the grouping of several taxa. Multivariate analysis of plasma metabolites and bacterial diversity produced a strong correlation of metabolic alterations, such as reduced short-chain fatty acids and an increase in primary bile acids, with a differential abundance of distinct bacteria in HF. In conclusion, we showed that HF begets HF, likely via a vicious cycle of an altered microbiome and metabolic products.