Current understanding of gut microbiota alterations and related therapeutic intervention strategies in heart failure

Targeting gut-immune-heart modulate cardiac remodeling after acute myocardial infarction

The gut microbiota interacts with the host to regulate disease and health status. An increasing number of studies have recognized the bidirectional regulation between gut microbiota and immune cells, which plays a significant role in the etiology and prognosis of diseases. Gut microbiota is also a crucial regulatory factor in cardiovascular diseases. After acute myocardial infarction, myocardial and endothelial damage rapidly triggers an inflammatory response, activating the immune system and disrupting the gut microbiota ecology, thereby affecting cardiac remodeling after acute myocardial infarction and potentially leading to heart failure. We have elucidated the regulatory mechanisms of complex intercellular networks in the immune system during cardiac remodeling after acute myocardial infarction. Furthermore, this research examines the roles and mechanisms of gut microbiota, immune cells, and gut metabolites in relation to cardiac remodeling and heart failure after myocardial infarction. Finally, we discuss the potential of targeting gut immune cells as an effective approach to prevent and treat heart failure after acute myocardial infarction in the future, through methods such as dietary regulation, probiotic supplementation, and microbiota transplantation.

The heart of the matter: How gut microbiota-targeted interventions influence cardiovascular diseases

The human body is habitat to a wide spectrum of microbial populations known as microbiota, which play an important role in overall health. The considerable research has mostly focused on the gut microbiota due to its potential to impact numerous physiological functions and its correlation with a variety of disorders, such as cardiovascular diseases (CVDs). Imbalances in the gut microbiota, known as dysbiosis, have been linked to the development and progression of CVDs through various processes, including the generation of metabolites like trimethylamine-N-oxide and short-chain fatty acids. Studies have also looked at the idea of using therapeutic interventions, like changing your diet, taking probiotics or prebiotics, or even fecal microbiota transplantation (FMT), to change the gut microbiota's make-up and how it works in order to prevent or treat CVDs. Exploring the cause-and-effect connection between the gut microbiota and CVDs offers a hopeful path for creating innovative microbiome-centered strategies to prevent and cure CVDs. This review presents an in-depth review of the correlation between the gut microbiota and CVDs, as well as potential therapeutic approaches for manipulating the gut microbiota to enhance cardiovascular health.

Gut microbiota-derived metabolites: Potential targets for cardiorenal syndrome

The characteristic of cardiorenal syndrome (CRS) is simultaneous damage to both the heart and kidneys. CRS has caused a heavy burden of mortality and incidence rates worldwide. The regulation of host microbiota metabolism that triggers heart and kidney damage is an emerging research field that promotes a new perspective on cardiovascular risk. We summarize current studies from bench to bedside of gut microbiota-derived metabolites to better understand CRS in the context of gut microbiota-derived metabolites. We focused on the involvement of gut microbiota-derived metabolites in the pathophysiology of CRS, including lipid and cholesterol metabolism disorders, coagulation abnormalities and platelet aggregation, oxidative stress, endothelial dysfunction, inflammation, mitochondrial damage and energy metabolism disorders, vascular calcification and renal fibrosis, as well as emerging therapeutic approaches targeting CRS metabolism in gut microbiota-derived metabolites which provides an innovative treatment approach for CRS to improve patient prognosis and overall quality of life.

Short-Chain Fatty Acids and Their Metabolic Interactions in Heart Failure

Short-chain fatty acids (SCFAs), produced through fermentation of dietary fibers by gut bacteria, play a central role in modulating cardiovascular function and heart failure (HF) development. The progression of HF is influenced by intestinal barrier dysfunction and microbial translocation, where SCFAs serve as key mediators in the gut-heart axis. This review examines the complex metabolic interactions between SCFAs and other gut microbiota metabolites in HF, including their relationships with trimethylamine N-oxide (TMAO), aromatic amino acids (AAAs), B vitamins, and bile acids (BAs). We analyze the associations between SCFA production and clinical parameters of HF, such as left ventricular ejection fraction (LVEF), N-terminal pro-B-type natriuretic peptide (NT-proBNP), and glomerular filtration rate (GFR). Gaining insights into metabolic networks offers new potential therapeutic targets and prognostic markers for managing heart failure, although their clinical significance needs further exploration.

Shenmai injection revives cardiac function in rats with hypertensive heart failure: involvement of microbial-host co-metabolism

Heart failure (HF) is a complex syndrome marked by considerable expenditures and elevated mortality and morbidity rates globally. Shenmai injection (SMI), a form of Traditional Chinese Medicine-based therapy, has demonstrated effectiveness in treating HF. Recent research suggests that Traditional Chinese Medicine (TCM) may induce beneficial changes in microbial-host co-metabolism, potentially providing cardiovascular protection. This study used a rat model of hypertensive heart failure (H-HF) to explore the mechanism of SMI. The possible compounds and key targets of SMI against H-HF were investigated using network pharmacology. The pharmacodynamics of SMI were validated using the H-HF animal model, with analysis of fecal gut microbiota integrating metabolomics and 16S rRNA sequencing. Metorigin metabolite traceability analysis and the MetaboAnalyst platform were utilized to explore the action mechanism. To evaluate changes in serum TMAO levels, targeted metabolomics was performed. Finally, the study looked at the intrinsic relationships among modifications in the intestinal flora, metabolite profile changes, and the targets of SMI compounds to clarify how they might be used to treat H-HF. According to metabolomics and 16S rRNA sequencing, by reestablishing homeostasis in the gut microbiota, SMI affects vital metabolic pathways, such as energy metabolism, amino acid metabolism, and bile acid metabolism. Increased serum TMAO levels were identified to be a risk factor for H-HF, and SMI was able to downregulate the levels of TMAO-related metabolites. Network pharmacology analysis identified 13 active components of SMI targeting 46 proteins, resulting in differential expression changes in 8 metabolites and 24 gut microbes. In conclusion, this study highlights the effectiveness of SMI in alleviating H-HF and its potential to modulate microbial-host co-metabolism. Through a comprehensive discussion of the interconnected relationships among the components, targets, metabolites, and gut microbiota, it provided fresh light on the therapeutic mechanism of SMI on H-HF.

The Role of Short-Chain Fatty Acids in Myocardial Ischemia-Reperfusion Injury

PURPOSE OF REVIEW

This study aims to review the effects of short-chain fatty acids (SCFAs) in regulating the myocardial ischemia-reperfusion injury (MIRI).

RECENT FINDINGS

Coronary heart disease (CHD) is a well-known leading cause of death and disability worldwide. Cardiac substrate metabolism plays the determinant role in assessing the severity of heart injury due to the abruptly shifted energy production during the MIRI. Fatty acids are the main energy fuels for the heart, which are classified into long-, medium- and short chain fatty acids by the length of carbon chain. SCFAs are the main metabolites derived from the anaerobic bacterial fermentation of fiber-rich diets, which are shown to play a protective role in cerebrovascular disease previously. Meanwhile, accumulating evidences suggest that SCFAs can also play a crucial role in cardiac energy metabolism. Results of various studies revealed the cardioprotective effects of SCFAs by displaying anti-inflammatory and anti-ferroptotic function, connecting gut-brain neural circuit and regulating the intestinal flora.

Gut microbiota and renal fibrosis

Renal fibrosis represents a critical pathological condition in the progression of renal dysfunction, characterized by aberrant accumulation of extracellular matrix (ECM) and structural alterations in renal tissue. Recent research has highlighted the potential significance of gut microbiota and demonstrated their influence on host health and disease mechanisms through the production of bioactive metabolites. This review examines the role of alterations in gut microbial composition and their metabolites in the pathophysiological processes underlying renal fibrosis. It delineates current therapeutic interventions aimed at modulating gut microbiota composition, encompassing dietary modifications, pharmacological approaches, and probiotic supplementation, while evaluating their efficacy in mitigating renal fibrosis. Through a comprehensive analysis of current research findings, this review enhances our understanding of the bidirectional interaction between gut microbiota and renal fibrosis, establishing a theoretical foundation for future research directions and potential clinical applications in this domain.

Underlying mechanisms of ketotherapy in heart failure: current evidence for clinical implementations

Heart failure (HF) is a life-threatening cardiac syndrome characterized by high morbidity and mortality, but current anti-heart failure therapies have limited efficacy, necessitating the urgent development of new treatment drugs. Exogenous ketone supplementation helps prevent heart failure development in HF models, but therapeutic ketosis in failing hearts has not been systematically elucidated, limiting the use of ketones to treat HF. Here, we summarize current evidence supporting ketotherapy in HF, emphasizing ketone metabolism in the failing heart, metabolic and non-metabolic therapeutic effects, and mechanisms of ketotherapy in HF, involving the dynamics within the mitochondria. We also discuss clinical strategies for therapeutic ketosis, aiming to deepen the understanding of the characteristics of ketone metabolism, including mitochondrial involvement, and its clinical therapeutic potential in HF.

Akkermansia muciniphila as a Potential Guardian against Oral Health Diseases: A Narrative Review

The oral microbiome is a diverse ecosystem containing a community of symbiotic, commensal, and pathogenic microorganisms. One key microorganism linked to periodontal disease (PD) is Porphyromonas gingivalis (P. gingivalis), a Gram-negative anaerobic bacterium known to have several virulence factors that trigger inflammation and immune evasion. On the other hand, Akkermansia muciniphila (A. muciniphila), a symbiotic bacterium, has been recently shown to play an important role in mitigating inflammation and reducing periodontal damage. In vivo and in vitro studies have shown that A. muciniphila decreases inflammatory mediators and improves immune responses, suggesting its role in mitigating PD and related inflammatory systemic conditions such as diabetes, hypertension, and obesity. This review discusses the anti-inflammatory effects of A. muciniphila, its impact on periodontal health, and its potential role in managing systemic diseases. The overall aim is to elucidate how this bacterium might help reduce inflammation, improve oral health, and influence broader health outcomes.

An Integrated Approach Based on Clinical Data Combined with Metabolites and Biomarkers for the Assessment of Post-Operative Complications after Cardiac Surgery

Background: Early diagnosis of post-operative complications is an urgent task, allowing timely prescribing of appropriate therapy and reducing the cost of patient treatment. The purpose of this study was to determine whether an integrated approach based on clinical data, along with metabolites and biomarkers, had greater predictive value than the models built on fewer data in the early diagnosis of post-operative complications after cardiac surgery. Methods: The study included patients (n = 62) admitted for planned cardiac surgery (coronary artery bypass grafting with cardiopulmonary bypass) with (n = 26) or without (n = 36) post-operative complications. Clinical and laboratory data on the first day after surgery were analyzed. Additionally, patients' blood samples were collected before and on the first day after surgery to determine biomarkers and metabolites. Results: Multivariate PLS-DA models, predicting the presence or absence of post-operative complications, were built using clinical data, concentrations of metabolites and biomarkers, and the entire data set (ROC-AUC = 0.80, 0.71, and 0.85, respectively). For comparison, we built univariate models using the EuroScore2 and SOFA scales, concentrations of lactate, the dynamic changes of 4-hydroxyphenyllactic acid, and the sum of three sepsis-associated metabolites (ROC-AUC = 0.54, 0.79, 0.62, 0.58, and 0.70, respectively). Conclusions: The proposed complex model using the entire dataset had the best characteristics, which confirms the expediency of searching for new predictive models based on a variety of factors.

Can Daily Dietary Choices Have a Cardioprotective Effect? Food Compounds in the Prevention and Treatment of Cardiometabolic Diseases

Cardiovascular diseases accompanying metabolic syndrome comprise one of the leading causes of death worldwide. The medical community undertakes attempts to improve treatment options and minimize cardiovascular diseases' numerous consequences and exacerbations. In parallel with pharmacotherapies provided by physicians, nutritionists are developing strategies for diet therapy and prevention based on lifestyle changes, with high success rates. Consumption of specified food compounds included in various products with proven protective properties can be helpful in this regard. Due to the wide possibilities of diet in metabolic health promotion, it seems necessary to systematize information about the metabolically protective and cardioprotective properties of fiber, probiotic bacteria, plant sterols, folic acid, vitamins B12, C, and E, PUFAs, lycopene, polyphenols, arginine, CoQ10, and allicin. The aim of this review was to present the food compounds with potential use in cardiometabolic prevention and diet therapy based on the latest available literature.

Altered Expression of Intestinal Tight Junction Proteins in Heart Failure Patients with Reduced or Preserved Ejection Fraction: A Pathogenetic Mechanism of Intestinal Hyperpermeability

Although intestinal microbiota alterations (dysbiosis) have been described in heart failure (HF) patients, the possible mechanisms of intestinal barrier dysfunction leading to endotoxemia and systemic inflammation are not fully understood. In this study, we investigated the expression of the intestinal tight junction (TJ) proteins occludin and claudin-1 in patients with HF with reduced (HFrEF) or preserved ejection fraction (HFpEF) and their possible association with systemic endotoxemia and inflammation. Ten healthy controls and twenty-eight patients with HF (HFrEF (n = 14), HFpEF (n = 14)) underwent duodenal biopsy. Histological parameters were recorded, intraepithelial CD3+ T-cells and the expression of occludin and claudin-1 in enterocytes were examined using immunohistochemistry, circulating endotoxin concentrations were determined using ELISA, and concentrations of cytokines were determined using flow cytometry. Patients with HFrEF or HFpEF had significantly higher serum endotoxin concentrations (p < 0.001), a significantly decreased intestinal occludin and claudin-1 expression (in HfrEF p < 0.01 for occludin, p < 0.05 for claudin-1, in HfpEF p < 0.01 occludin and claudin-1), and significantly increased serum concentrations of IL-6, IL-8, and IL-10 (for IL-6 and IL-10, p < 0.05 for HFrEF and p < 0.001 for HFpEF; and for IL-8, p < 0.05 for both groups) compared to controls. Occludin and claudin-1 expression inversely correlated with systemic endotoxemia (p < 0.05 and p < 0.01, respectively). Heart failure, regardless of the type of ejection fraction, results in a significant decrease in enterocytic occludin and claudin-1 expression, which may represent an important cellular mechanism for the intestinal barrier dysfunction causing systemic endotoxemia and inflammatory response.

A new perspective in the prevention and treatment of antitumor therapy-related cardiotoxicity: Intestinal microecology

The continuous development of antitumor therapy has significantly reduced the mortality of patients with malignancies. However, the antitumor-related cardiotoxicity has become the leading cause of long-term mortality in patients with malignancies. Besides, the pathogenesis of antitumor-related cardiotoxicity is still unclear, and practical means of prevention and treatment are lacking in clinical practice. Therefore, the major challenge is how to combat the cardiotoxicity of antitumor therapy effectively. More and more studies have shown that antitumor therapy kills tumor cells while causing damage to sensitive tissues such as the intestinal mucosa, leading to the increased permeability of the intestine and the dysbiosis of intestinal microecology. In addition, the dysbiosis of intestinal microecology contributes to the development and progression of cardiovascular diseases through multiple pathways. Thus, the dysbiosis of intestinal microecology may be a potential mechanism and target for antitumor-related cardiotoxicity. We summarized the characteristics of intestinal microecology disorders induced by antitumor therapy and the association between intestinal microecological dysbiosis and CVD. And on this basis, we hypothesized the potential mechanisms of intestinal microecology mediating the occurrence of antitumor-related cardiotoxicity. Then we reviewed the previous studies targeting intestinal microecology against antitumor-associated cardiotoxicity, aiming to provide a reference for future studies on the occurrence and prevention of antitumor-related cardiotoxicity by intestinal microecology.

Human Gut Microbiota in Heart Failure: Trying to Unmask an Emerging Organ

There is a bidirectional relationship between the heart and the gut. The gut microbiota, the community of gut micro-organisms themselves, is an excellent gut-homeostasis keeper since it controls the growth of potentially harmful bacteria and protects the microbiota environment. There is evidence suggesting that a diet rich in fatty acids can be metabolized and converted by gut microbiota and hepatic enzymes to trimethyl-amine N-oxide (TMAO), a product that is associated with atherogenesis, platelet dysfunction, thrombotic events, coronary artery disease, stroke, heart failure (HF), and, ultimately, death. HF, by inducing gut ischemia, congestion, and, consequently, gut barrier dysfunction, promotes the intestinal leaking of micro-organisms and their products, facilitating their entrance into circulation and thus stimulating a low-grade inflammation associated with an immune response. Drugs used for HF may alter the gut microbiota, and, conversely, gut microbiota may modify the pharmacokinetic properties of the drugs. The modification of lifestyle based mainly on exercise and a Mediterranean diet, along with the use of pre- or probiotics, may be beneficial for the gut microbiota environment. The potential role of gut microbiota in HF development and progression is the subject of this review.

Cardioprotective properties of quercetin in fescue toxicosis-induced cardiotoxicity via heart-gut axis in lambs (Ovis Aries)

The present study investigated whether quercetin mitigated fescue toxicosis-induced cardiovascular injury via the heart-gut axis. Twenty-four commercial Dorper lambs were stratified by body weight and assigned randomly to diets in one of four groups: endophyte-free without quercetin (E-,Q-), endophyte-positive without quercetin (E+,Q-), endophyte-positive plus 4 g/kg quercetin (E+,Q+) or endophyte-free plus 4 g/kg quercetin (E-,Q+) for 42 days. Body weight and average daily feed intake (ADFI) of lambs fed the endophyte-positive diets showed significant decreases. However, in the groups treated with quercetin, there were significant alterations of cardiac enzymes. Furthermore, reduced fescue toxicosis-induced histopathological lesions of heart and aorta were demonstrated in the E+,Q+ lambs. Results also suggested quercetin eased cardiovascular oxidative injury by inhibiting the increase of oxidative metabolites, and enhancing the levels of antioxidases. Quercetin reduced the inflammation response through suppressing NF-κB signaling pathway activation. Additionally, quercetin ameliorated fescue toxicosis-induced mitochondria dysfunction and improved mitochondrial quality control through enhancing PGC-1α-mediated mitochondrial biogenesis, maintaining the mitochondrial dynamics, and relieving aberrant Parkin/PINK-mediated mitophagy. Quercetin enhanced gastrointestinal microbial alpha and beta diversity, alleviated gut microbiota and microbiome derived metabolites-SCFAs dysbiosis by fescue toxicosis. These findings signified that quercetin may play a cardio-protective role via regulating the heart-gut microbiome axis.

Cardiometabolic Risk: Characteristics of the Intestinal Microbiome and the Role of Polyphenols

Cardiometabolic diseases like hypertension, type 2 diabetes mellitus, atherosclerosis, and obesity have been associated with changes in the gut microbiota structure, or dysbiosis. The beneficial effect of polyphenols on reducing the incidence of this chronic disease has been confirmed by numerous studies. Polyphenols are primarily known for their anti-inflammatory and antioxidant properties, but they can also modify the gut microbiota. According to recent research, polyphenols positively influence the gut microbiota, which regulates metabolic responses and reduces systemic inflammation. This review emphasizes the prebiotic role of polyphenols and their impact on specific gut microbiota components in patients at cardiometabolic risk. It also analyzes the most recent research on the positive effects of polyphenols on cardiometabolic health. While numerous in vitro and in vivo studies have shown the interaction involving polyphenols and gut microbiota, additional clinical investigations are required to assess this effect in people.

Bacterial toxins and heart function: heat-labile Escherichia coli enterotoxin B promotes changes in cardiac function with possible relevance for sudden cardiac death

Bacterial toxins can cause cardiomyopathy, though it is not its most common cause. Some bacterial toxins can form pores in the membrane of cardiomyocytes, while others can bind to membrane receptors. Enterotoxigenic E. coli can secrete enterotoxins, including heat-resistant (ST) or labile (LT) enterotoxins. LT is an AB5-type toxin that can bind to specific cell receptors and disrupt essential host functions, causing several common conditions, such as certain diarrhea. The pentameric B subunit of LT, without A subunit (LTB), binds specifically to certain plasma membrane ganglioside receptors, found in lipid rafts of cardiomyocytes. Isolated guinea pig hearts and cardiomyocytes were exposed to different concentrations of purified LTB. In isolated hearts, mechanical and electrical alternans and an increment of heart rate variability, with an IC50 of ~0.2 μg/ml LTB, were observed. In isolated cardiomyocytes, LTB promoted significant decreases in the amplitude and the duration of action potentials. Na+ currents were inhibited whereas L-type Ca2+ currents were augmented at their peak and their fast inactivation was promoted. Delayed rectifier K+ currents decreased. Measurements of basal Ca2+ or Ca2+ release events in cells exposed to LTB suggest that LTB impairs Ca2+ homeostasis. Impaired calcium homeostasis is linked to sudden cardiac death. The results are consistent with the recent view that the B subunit is not merely a carrier of the A subunit, having a role explaining sudden cardiac death in children (SIDS) infected with enterotoxigenic E. coli, explaining several epidemiological findings that establish a strong relationship between SIDS and ETEC E. coli.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12551-023-01100-6.

Gut microbiota and integrative traditional Chinese and western medicine in prevention and treatment of heart failure

BACKGROUND

Heart failure (HF) is the terminal stage of multiple cardiovascular diseases, with high mortality and morbidity. More and more studies have proved that gut microbiota may play a role in the process of HF, which is expected to become a new therapeutic target. The combination of traditional Chinese and Western medicine has vast therapeutic potential of complementation against HF.

PURPOSE

This manuscript expounds on the research progress of mechanisms of gut microbiota participating in the occurrence and prognosis of HF and the role of integrative traditional Chinese and Western medicine from 1987 to 2022. The combination of traditional Chinese and Western medicine in the prevention and treatment of HF from the perspective of gut microbiota has been discussed.

METHODS

Studies focusing on the effects and their mechanisms of gut microbiota in HF and the role of integrative traditional Chinese and Western medicine were identified and summarized, including contributions from February 1987 until August 2022. The investigation was carried out in accordance with the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines. We searched PubMed, Embase, Cochrane Library, CNKI, Wanfang, and VIP databases up to April 2023 by using the relevant keywords and operators.

RESULTS

A total of 34 articles were finally included in this review.16 RCTs and 13 basic researches, and 3 clinical research studies involving 7 relevant outcome indicators(cardiac function evaluation index, changes in gut microbiota, inflammatory factors, metabolites of gut microbiota, serum nutritional index protein, quality of life score, intestinal permeability and all-cause mortality). Compared with healthy controls, serum TNF-α and TMAO levels were significantly higher in patients with heart failure [MD = 5.77, 95%CI(4.97, 6.56), p < 0.0001; SMD = 1.92, 95%CI(1.70, 2.14), p < 0.0001]. Escherichia coli and Thick-walled bacteria increased significantly [SMD = -0.99, 95%CI(-1.38, -0.61), p < 0.0001, SMD = 2.58, 95%CI(2.23, 2.93), p < 0.0001];The number of bacteroides and lactobacillus decreased [SMD = -2.29, 95%CI(-2.54, -2.04), p < 0.0001; SMD = -1.55, 95%CI(-1.8, -1.3), p < 0.0001]. There was no difference in bifidobacterium [SMD = 0.16, 95%CI(-0.22, 0.54), p = 0.42]. In the published literature, it is not difficult to see that most of the results are studied and proved based on animal experiments or clinical trials, involving the cellular level, while the mechanism and mode of action of the molecular biology of traditional Chinese medicine are less elaborated, which is related to the characteristics of multi-components and multi-targets of traditional Chinese medicine. The above are the shortcomings of published literature, which can also be the direction of future research.

CONCLUSION

Heart failure patients have decreased beneficial bacteria such as Bacillus mimics and Lactobacillus in the intestinal flora and increased harmful flora like thick-walled flora. And increase the inflammatory response of the body and the expression of trimethylamine oxide (TMAO) in the serum. And The prevention and treatment of integrative traditional Chinese and Western medicine against heart failure based on gut microbiota and its metabolites is a promising research direction.

Microbiota Metabolism Failure as a Risk Factor for Postoperative Complications after Aortic Prosthetics

Postoperative complications in cardiovascular surgery remain an important unresolved problem, in particular in patients with aortic aneurysm. The role of the altered microbiota in such patients is of great interest. The aim of this pilot study was to determine whether the development of postoperative complications in patients with aortic aneurysm is related with initial or acquired disorders of microbiota metabolism by monitoring the level of some aromatic microbial metabolites (AMMs) circulating in the blood before the surgery and in the early postoperative period. The study comprised patients with aortic aneurysm (n = 79), including patients without complications (n = 36) and patients with all types of complications (n = 43). The serum samples from the patients were collected before and 6 h after the end of the surgery. The most significant results were obtained for the sum of three sepsis-associated AMMs. This level was higher before the surgery in comparison with that of healthy volunteers (n = 48), p < 0.001, and it was also higher in the early postoperative period in patients with all types of complications compared to those without complications, p = 0.001; the area under the ROC curve, the cut-off value, and the odds ratio were 0.7; 2.9 µmol/L, and 5.5, respectively. Impaired microbiota metabolism is important in the development of complications after complex reconstructive aortic surgery, which is the basis for the search for a new prevention strategy.

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.

Dysbiosis of Gut Microbiota Contributes to Uremic Cardiomyopathy via Induction of IFNγ-Producing CD4+ T Cells Expansion

Uremic cardiomyopathy (UCM) correlates with chronic kidney disease (CKD)-induced morbidity and mortality. Gut microbiota has been involved in the pathogenesis of certain cardiovascular disease, but the role of gut microbiota in the pathogenesis of UCM remains unknown. Here, we performed a case-control study to compare the gut microbiota of patients with CKD and healthy controls by 16S rRNA (rRNA) gene sequencing. To test the causative relationship between gut microbiota and UCM, we performed fecal microbiota transplantation (FMT) in 5/6th nephrectomy model of CKD. We found that opportunistic pathogens, particularly Klebsiella pneumoniae (K. pneumoniae), are markedly enriched in patients with CKD. FMT from CKD patients aggravated diastolic dysfunction in the mouse model. The diastolic dysfunction was associated with microbiome-dependent increases in heart-infiltrating IFNγ+ CD4+ T cells. Monocolonization with K. pneumoniae increased cardiac IFNγ+ CD4+ T cells infiltration and promoted UCM development of the mouse model. A probiotic Bifidobacterium animalis decreased the relative abundance of K. pneumoniae, reduced levels of cardiac IFNγ+ CD4+ T cells and ameliorated the severity of diastolic dysfunction in the mice. Thus, the aberrant gut microbiota in CKD patients, especially K. pneumoniae, contributed to UCM pathogenesis through the induction of heart-infiltrating IFNγ+ CD4+ T cells expansion, proposing that a Gut Microbiota-Gut-Kidney-Heart axis could play a critical role in elucidating the etiology of UCM, and suggesting that modulation of the gut bacteria may serve as a promising target for the amelioration of UCM. IMPORTANCE Uremic cardiomyopathy (UCM) correlates tightly with increased mortality in patients with chronic kidney disease (CKD), yet the pathogenesis of UCM remains incompletely understood, limiting therapeutic approaches. Our study proposed that a Gut Microbiota-Gut-Kidney-Heart axis could play a critical role in understanding etiology of UCM. There is a major need in future clinical trials of patients with CKD to explore if modulation of gut microbiota by fecal microbiota transplantation (FMT), probiotics or antibiotics can alleviate cardiac dysfunction, reduce mortality, and improve life quality.

In vitro gut microbiome response to carbohydrate supplementation is acutely affected by a sudden change in diet

BACKGROUND

Interactions between diet, stress and the gut microbiome are of interest as a means to modulate health and performance. Here, in vitro fermentation was used to explore the effects of a sudden change in diet, 21 days sole sustenance on the Meal, Ready-to-Eat (MRE) U.S. military combat ration, on inter-species competition and functional potential of the human gut microbiota. Human fecal samples collected before and after MRE intervention or consuming a habitual diet (HAB) were introduced to nutrient-rich media supplemented with starch for in vitro fermentation under ascending colon conditions. 16S rRNA amplicon and Whole-metagenome sequencing (WMS) were used to measure community composition and functional potential. Specific statistical analyses were implemented to detect changes in relative abundance from taxa, genes and pathways.

RESULTS

Differential changes in relative abundance of 11 taxa, Dorea, Lachnospira, Bacteroides fragilis, Akkermansia muciniphila, Bifidobacterium adolescentis, Betaproteobacteria, Enterobacteriaceae, Bacteroides egerthii, Ruminococcus bromii, Prevotella, and Slackia, and nine Carbohydrate-Active Enzymes, specifically GH13_14, over the 24 h fermentation were observed as a function of the diet intervention and correlated to specific taxa of interest.

CONCLUSIONS

These findings suggest that consuming MRE for 21 days acutely effects changes in gut microbiota structure in response to carbohydrate but may induce alterations in metabolic capacity. Additionally, these findings demonstrate the potential of starch as a candidate supplemental strategy to functionally modulate specific gut commensals during stress-induced states.

A bibliometric analysis of research on heart failure comorbid with depression from 2002 to 2021

Heart failure (HF) with depression is a common comorbidity associated with worse clinical status and quality of life. Although there have been numerous high-quality studies and relevant reviews on HF comorbid with depression, few bibliometric analyses of this field have been reported. In order to understand the development process, research hotspots and future directions, this review analyzes the papers on HF comorbid with depression from January 2002 to December 2021 through CiteSpace and VOSviewer. Visual cooperative networks between countries, authors and institutions were conducted to understand the basic development status of HF comorbid with depression. Furthermore, we performed co-occurrence analysis, burst detection, and timeline analysis for keywords to understand this field's research directions and hotspots. Finally, a detailed review and analysis of the classical literature in this field were conducted based on co-citation analysis. This bibliometric analysis provides an overview of studies on HF comorbid with depression and emphasizes the research on comorbidity mechanisms and more effective interventions as a priority for future research.

The Role of Gut Microbiota in Heart Failure: When Friends Become Enemies

Heart failure is a complex health issue, with important consequences on the overall wellbeing of patients. It can occur both in acute and chronic forms and, in the latter, the immune system appears to play an important role in the pathogenesis of the disease. In particular, in the forms with preserved ejection fraction or with only mildly reduced ejection fraction, some specific associations with chronic inflammatory diseases have been observed. Another interesting aspect that is worth considering is the role of microbiota modulation, in this context: given the importance of microbiota in the modulation of immune responses, it is possible that changes in its composition may somewhat influence the progression and even the pathogenesis of heart failure. In this narrative review, we aim to examine the relationship between immunity and heart failure, with a special focus on the role of microbiota in this pathological condition.

The impact of probiotic yogurt versus ordinary yogurt on serum sTWEAK, sCD163, ADMA, LCAT and BUN in patients with chronic heart failure: a randomized, triple-blind, controlled trial

BACKGROUND

To date, no study has investigated the effects of probiotic yogurt as a functional food in patients with chronic heart failure (CHF). Therefore, the aim of this study was to compare the impact of probiotic yogurt versus ordinary yogurt on inflammatory, endothelial, lipid and renal indices in CHF patients. In this randomized, triple-blind clinical trial, 90 patients with CHF were randomly allocated into two groups to take either probiotic or ordinary yogurt for 10 weeks. Serum levels of soluble tumor necrosis factor-like weak inducer of apoptosis (sTWEAK), soluble cluster of differentiation 163 (sCD163), asymmetric dimethylarginine (ADMA), and lecithin cholesterol acyltransferase (LCAT) were measured by using ELISA kits, and blood urea nitrogen (BUN) was measured by calorimetry method at baseline and at the end of trial. The P-value <0.05 was defined as statistically significant.

RESULTS

Seventy-eight patients completed the study. At the end of the intervention, the levels of sTWEAK in both groups increased significantly, and this increase was greater in the probiotic yogurt group [691.84 (335.60, 866.95)] compared to control group [581.96 (444.99, 929.40)], and the difference between the groups was statistically significant after adjusting for confounders (P-value: 0.257, adjusted P-value: 0.038). However, no significant differences were found between the groups in the cases of other study indices.

CONCLUSION

Probiotic yogurt may be useful for improving the inflammatory status in patients with CHF through increasing sTWEAK levels, however, further studies are needed in this area. © 2022 Society of Chemical Industry.

The potential impact of a probiotic: Akkermansia muciniphila in the regulation of blood pressure—the current facts and evidence

Akkermansia muciniphila (A. muciniphila) is present in the human gut microbiota from infancy and gradually increases in adulthood. The potential impact of the abundance of A. muciniphila has been studied in major cardiovascular diseases including elevated blood pressure or hypertension (HTN). HTN is a major factor in premature death worldwide, and approximately 1.28 billion adults aged 30–79 years have hypertension. A. muciniphila is being considered a next-generation probiotic and though numerous studies had highlighted the positive role of A. muciniphila in lowering/controlling the HTN, however, few studies had highlighted the negative impact of increased abundance of A. muciniphila in the management of HTN. Thus, in the review, we aimed to discuss the current facts, evidence, and controversy about the role of A. muciniphila in the pathophysiology of HTN and its potential effect on HTN management/regulation, which could be beneficial in identifying the drug target for the management of HTN.

Gut Microbiota Modulation as a Novel Therapeutic Strategy in Cardiometabolic Diseases

The human gut harbors microbial ecology that is in a symbiotic relationship with its host and has a vital function in keeping host homeostasis. Inimical alterations in the composition of gut microbiota, known as gut dysbiosis, have been associated with cardiometabolic diseases. Studies have revealed the variation in gut microbiota composition in healthy individuals as compared to the composition of those with cardiometabolic diseases. Perturbation of host-microbial interaction attenuates physiological processes and may incite several cardiometabolic disease pathways. This imbalance contributes to cardiometabolic diseases via metabolism-independent and metabolite-dependent pathways. The aim of this review was to elucidate studies that have demonstrated the complex relationship between the intestinal microbiota as well as their metabolites and the development/progression of cardiometabolic diseases. Furthermore, we systematically itemized the potential therapeutic approaches for cardiometabolic diseases that target gut microbiota and/or their metabolites by following the pathophysiological pathways of disease development. These approaches include the use of diet, prebiotics, and probiotics. With the exposition of the link between gut microbiota and cardiometabolic diseases, the human gut microbiota therefore becomes a potential therapeutic target in the development of novel cardiometabolic agents.

Associations between the gut microbiome, gut microbiology and heart failure: Current understanding and future directions

The role of the gut microbiome in pathophysiology, prognostication and clinical management of heart failure (HF) patients is of great clinical and research interest. Both preclinical and clinical studies have shown promising results, and the gut microbiome has been implicated in other cardiovascular conditions that are risk factors for HF. There is an increasing interest in the use of biological compounds produced as biomarkers for prognostication as well as exploration of therapeutic options targeting the various markers and pathways from the gut microbiome that are implicated in HF. However, study variations exist, and targeted research for individual putative biomarkers is necessary. There is also limited evidence pertaining to decompensated HF in particular. In this review, we synthesize current understandings around pathophysiology, prognostication and clinical management of heart failure (HF) patients, and also provide an outline of potential areas of future research and scientific advances.

Knowledge Mapping of the Links Between the Gut Microbiota and Heart Failure: A Scientometric Investigation (2006–2021)

Background

There is considerable research value and extensive application perspectives to explore the link between gut microbiota and heart failure. The purpose of this study is to provide an overview of overall characteristics, evolutionary pathways, frontier research hotspots, and future trends in this field.

Methods

Research datasets were acquired from the Web of Science Core Collection (WoSCC) between January 1, 2006 and December 31, 2021. Three different analysis tools including one online platform, VOS viewer V1.6.17.0, and CiteSpace V5.8.R2 software were used in order to conduct collaboration network analysis, co-cited analysis, co-occurring analysis, and citation burst detection.

Results

A total of 873 publications in the WoSCC database met the requirement. The overall characteristics analysis showed that a steady growth trend in the number of publications and citations, with the predominant literature type being articles and the most frequent subject category being cardiac cardiovascular systems. The United States was the most prolific country and the center of national collaboration. Cleveland Clinic and Nathalie M. Delzenne provided the leading influence with publications, the cooperation between the institutes and authors were relatively weak. Moreover, gut microbiota, heart failure, risk factor, obesity, and inflammation were the keywords that appeared more frequently in the clustering analysis of reference co-citation and keyword co-occurrence. Burst detection analysis of top keywords showed that trimethylamine N-oxide (TMAO), bile acid, blood pressure, hypertension, and fermentation were the new research foci on the association between gut microbiota and heart failure. Strategies to improve gut microbiota hold promise as a new approach to treat heart failure.

Conclusion

The comprehensive bibliometric study indicates that the structured information may be helpful in understanding research trends in the link between gut microbiota and heart failure, and locating research hotspots and gaps in this domain, especially further advances in this field will lead to significant breakthroughs in the development of novel therapeutic tools for metabolic modulation of heart failure.

The Effect of Synbiotic Consumption on Serum NTproBNP, hsCRP and Blood Pressure in Patients With Chronic Heart Failure: A Randomized, Triple-Blind, Controlled Trial

BACKGROUND

In recent years, there has been a positive attitude toward gut microbiota and its effect on cardiovascular diseases, including heart failure.

OBJECTIVE

The purpose of this study was to evaluate the effect of synbiotics on left ventricular hypertrophy by measuring NT-proBNP, and their effect on blood pressure and hsCRP as an inflammatory biomarker in patients with chronic heart failure.

DESIGN

In this triple-blind randomized clinical trial, 90 eligible patients were included in the study. They were randomly assigned to receive one capsule (500 mg) of synbiotics or placebo per day for 10 weeks. NTproBNP, hsCRP and blood pressure were measured at the beginning and end of the study. Statistical analysis was performed on 80 patients by using SPSS 24, and p < 0.05 as statistically significant.

RESULT

At the end of the study, the level of NT-proBNP decreased significantly in the synbiotic group compared to the placebo group (r = -256.55; P = 0.04). However, hsCRP increased in both groups as compared to the beginning of the study, but only in the placebo group the increase in hsCRP was significant (P = 0.01). The results showed that the changes in hs-CRP was not significant between the two groups. No statistically significant differences were observed in systolic and diastolic blood pressure between the two groups at the end of the intervention.

CONCLUSION

Synbiotics have favorable effect on cardiac hypertrophy index (NT-proBNP). Although the inflammatory factor increased in both groups, the significant increase in hsCRP in the placebo group could indicate the beneficial effects of synbiotics on the inflammatory status of these patients.

CLINICAL TRIAL REGISTRATION

https://en.irct.ir/user/trial/42905/view, identifier: IRCT20091114002709N52.

Bacterial diversity in the intestinal mucosa of heart failure rats treated with Sini Decoction

Background

Sini Decoction (SND), a classic Chinese medicine prescription, has been proved to have a good effect on heart failure (HF), whereas its underlying mechanism is still unclear. In order to explore the therapeutic mechanism of SND, we combined with 16S rRNA gene sequencing to analyze the composition of gut microflora in rats with HF.

Material and methods

Twenty Sprague–Dawley (SD) rats were divided into four groups (n = 5): normal group, model group, SND treatment group (SNT group), and metoprolol (Met) treatment group (Meto group). All the rats except the normal group were intraperitoneally injected with doxorubicin (concentration 2 mg/mL, dose 0.15 mL/100 g) once a week to induce HF. After successfully modeling, SND and Met were gavaged to rats, respectively. After the treatment period, blood was collected for hematological analyses, myocardial tissue and colon tissues were collected for Hematoxylin–Eosin (H&E) staining, and mucosal scrapings were collected for Illumina Miseq high-throughput sequencing.

Results

Echocardiographic results suggested that both left ventricular ejection fraction (LVEF) and left ventricular fraction shortening (LVFS) in Model rats decreased compared with normal rats. The results of H&E staining showed that compared with the model group, the structures of myocardial tissue and colon tissue in the SNT group and Meto group showed a recovery trend. Alpha results showed that the model group had higher species diversity and richness compared with the normal group. After treatment, the richness and diversity of intestinal bacteria in the SNT group were significantly restored, and Met also showed the effect of adjusting bacterial diversity, but its effect on bacterial richness was not ideal. At the Family level, we found that the number of several bacteria associated with HF in the model group increased significantly. Excitingly, SND and Met had shown positive effects in restoring these HF-associated bacteria. Similarly, the results of Linear discriminant analysis (LDA) showed that both SND and Met could reduce the accumulation of bacteria in the model group caused by HF.

Conclusion

Collectively, SND can improve HF by regulating the intestinal flora. This will provide new ideas for the clinical treatment of patients with HF.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12906-022-03575-4.

Faecal DNA metabarcoding reveals novel bacterial community patterns of critically endangered Southern River Terrapin, Batagur affinis

Southern River Terrapin, Batagur affinis, is a freshwater turtle listed as critically endangered on the IUCN Red List since 2000. Many studies suggest that faecal DNA metabarcoding can shield light on the host-associated microbial communities that play important roles in host health. Thus, this study aimed to characterise and compare the faecal bacterial community between captive and wild B. affinis using metabarcoding approaches. A total of seven faeces samples were collected from captive (N = 5) and wild (N = 2) adult B. affinis aseptically, crossing the East and West coast of peninsular Malaysia. The DNA was extracted from the faeces samples, and the 16S rRNA gene (V3-V4 region) was amplified using polymerase chain reaction (PCR). The amplicon was further analysed using SILVA and DADA2 pipelines. In total, 297 bacterial communities taxonomic profile (phylum to genus) were determined. Three phyla were found in high abundance in all faeces samples, namely Firmicutes (38.69%), Bacteroidetes (24.52%), and Fusobacteria (6.95%). Proteobacteria were detected in all faeces samples (39.63%), except the wild sample, KBW3. Under genus level, Cetobacteriumwas found as the most abundant genus (67.79%), followed by Bacteroides (24.56%) and Parabacteroides (21.78%). The uncultured genus had the highest abundance (88.51%) even though not detected in the BK31 and KBW2 samples. The potential probiotic genera (75.00%) were discovered to be more dominant in B. affinis faeces samples. Results demonstrated that the captive B. affinis faeces samples have a greater bacterial variety and richness than wild B. affinis faeces samples. This study has established a starting point for future investigation of the gut microbiota of B. affinis.

Gut Microbiota in Heart Failure Patients With Preserved Ejection Fraction (GUMPTION Study)

Introduction: Heart failure with preserved ejection fraction (HFpEF) is associated with disrupted intestinal epithelial function, resulting from intestinal congestion. Intestinal congestion changes the morphology and permeability of the intestinal wall, and it becomes easy for the gut microbiota to change and transfer. Intervention on gut microbiota may become a new target for HFpEF treatment. However, the characteristics of gut microbiota in patients with HFpEF remain unknown. This preliminary report aims to detect the structure of gut microbiota in HFpEF patients so as to explore their characteristic changes, thereby providing a theoretical basis for future research. Methods: This research recruited 30 patients diagnosed with HFpEF and 30 healthy individuals. Stool specimens of research subjects were collected separately, and the microarray analyses of gut microbiota were conducted by Illumina high-throughput DNA sequencing. The differences in gut microbiota composition, alpha diversity, and beta diversity between the two groups were finally obtained. Results: The composition of gut microbiota was significantly different between the two groups. At the phylum classification level, the abundance of Synergistetes tended to be higher in the HFpEF group (P = 0.012). At genus classification level, the abundance of Butyricicoccus (P < 0.001), Sutterella (P = 0.004), Lachnospira (P = 0.003), and Ruminiclostridium (P = 0.009) in the HFpEF group were lower, while the abundance of Enterococcus (P < 0.001) and Lactobacillus (P = 0.005) were higher. According to the Chao index of alpha diversity analysis, HFpEF patients showed a nominally significant lower species richness when compared with controls (P = 0.046). However, there was no statistical difference in the Shannon index (P = 0.159) and Simpson index (P = 0.495), indicating that there was no difference in species diversity between the two groups. Beta diversity analysis revealed a highly significant separation of HFpEF patients and controls. Conclusions: An imbalance in the gut microbiota of HFpEF patients was observed. Patients with HFpEF have an increased abundance of microbiota associated with inflammation and a decreased abundance of microbiota associated with anti-inflammatory effects in the gut environment. In line with that, the species richness of gut microbiota in HFpEF patients tended to be lower.

The Identification of Key Genes and Biological Pathways in Heart Failure by Integrated Bioinformatics Analysis

Purpose

Heart failure (HF) is a clinical syndrome caused by ventricular insufficiency. In order to further explore the biomarkers related to HF, we apply the high-throughput database.

Materials and Methods

The GSE21610 was applied for the differentially expressed gene (DEG) analysis. The Database for Annotation, Visualization, and Integrated Discovery (DAVID) was performed to assess Gene ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses. The Gene Set Enrichment Analysis (GSEA) was used for gene expression profile GSE21610. The Protein-Protein Interaction (PPI) network and modules were also constructed for research. These hub gene function pathways were estimated in HF progression.

Result

We have identified 434 DEGs in total, including 304 downregulated DEGs and 130 upregulated DEGs. GO and KEGG illustrated that DEGs in HF were significantly enriched in G protein-coupled receptor binding, peroxisome, and cAMP signaling pathway. GSEA results showed gene set GSE21610 was gathered in lipid digestion, defense response to fungus, and intestinal lipid absorption. Finally, through analyzing the PPI network, we screened hub genes CDH1, TFRC, CCL2, BUB1B, and CD19 by the Cytoscape software.

Conclusion

This study uses a series of bioinformatics technologies to obtain hug genes and key pathways related to HF. These analysis results provide us with new ideas for finding biomarkers and treatment methods for HF.

Over-feeding the gut microbiome: A scoping review on health implications and therapeutic perspectives

The human gut microbiome has gained increasing attention over the past two decades. Several findings have shown that this complex and dynamic microbial ecosystem can contribute to the maintenance of host health or, when subject to imbalances, to the pathogenesis of various enteric and non-enteric diseases. This scoping review summarizes the current knowledge on how the gut microbiota and microbially-derived compounds affect host metabolism, especially in the context of obesity and related disorders. Examples of microbiome-based targeted intervention strategies that aim to restore and maintain an eubiotic layout are then discussed. Adjuvant therapeutic interventions to alleviate obesity and associated comorbidities are traditionally based on diet modulation and the supplementation of prebiotics, probiotics and synbiotics. However, these approaches have shown only moderate ability to induce sustained changes in the gut microbial ecosystem, making the development of innovative and tailored microbiome-based intervention strategies of utmost importance in clinical practice. In this regard, the administration of next-generation probiotics and engineered microbiomes has shown promising results, together with more radical intervention strategies based on the replacement of the dysbiotic ecosystem by means of fecal microbiota transplantation from healthy donors or with the introduction of synthetic communities specifically designed to achieve the desired therapeutic outcome. Finally, we provide a perspective for future translational investigations through the implementation of bioinformatics approaches, including machine and deep learning, to predict health risks and therapeutic outcomes.

Gut Microbiota as Early Predictor of Infectious Complications before Cardiac Surgery: A Prospective Pilot Study

Cardiac surgery remains a field of medicine with a high percentage of postoperative complications, including infectious ones. Modern data indicate a close relationship of infectious disorders with pathological changes in the composition of the gut microbiome; however, the extent of such changes in cardiac surgery patients is not fully clarified. In this prospective, observational, single center, pilot study, 72 patients were included, 12 among them with the infectious complications. We analyzed the features of the fecal microbiota before and in the early postoperative period, as one of the markers for predicting the occurrence of bacterial infection. We also discovered the significant change in microbial composition in the group of patients with infectious complications compared to the non-infectious group before and after cardiac surgery, despite the intra-individual variation in composition of gut microbiome. Our study demonstrated that the group of patients that had a bacterial infection in the early postoperative period already had an altered microbial composition even before the surgery. Further studies will evaluate the clinical significance of the identified proportions of individual taxa of the intestinal microbiota and consider the microbiota as a novel target for reducing the risk of infectious complications.

Dysbiosis, Host Metabolism, and Non-communicable Diseases: Trialogue in the Inborn Errors of Metabolism

Inborn errors of metabolism (IEMs) represent a complex system model, in need of a shift of approach exploring the main factors mediating the regulation of the system, internal or external and overcoming the traditional concept of biochemical and genetic defects. In this context, among the established factors influencing the metabolic flux, i.e., diet, lifestyle, antibiotics, xenobiotics, infectious agents, also the individual gut microbiota should be considered. A healthy gut microbiota contributes in maintaining human health by providing unique metabolic functions to the human host. Many patients with IEMs are on special diets, the main treatment for these diseases. Hence, IEMs represent a good model to evaluate how specific dietary patterns, in terms of macronutrients composition and quality of nutrients, can be related to a characteristic microbiota associated with a specific clinical phenotype (“enterophenotype”). In the present review, we aim at reporting the possible links existing between dysbiosis, a condition reported in IEMs patients, and a pro-inflammatory status, through an altered “gut-liver” cross-talk network and a major oxidative stress, with a repercussion on the health status of the patient, increasing the risk of non-communicable diseases (NCDs). On this basis, more attention should be paid to the nutritional status assessment and the clinical and biochemical signs of possible onset of comorbidities, with the goal of improving the long-term wellbeing in IEMs. A balanced intestinal ecosystem has been shown to positively contribute to patient health and its perturbation may influence the clinical spectrum of individuals with IEMs. For this, reaching eubiosis through the improvement of the quality of dietary products and mixtures, the use of pre-, pro- and postbiotics, could represent both a preventive and therapeutic strategy in these complex diseases.

A guide to human microbiome research: study design, sample collection, and bioinformatics analysis

The purpose of this review is to provide medical researchers, especially those without a bioinformatics background, with an easy-to-understand summary of the concepts and technologies used in microbiome research. First, we define primary concepts such as microbiota, microbiome, and metagenome. Then, we discuss study design schemes, the methods of sample size calculation, and the methods for improving the reliability of research. We emphasize the importance of negative and positive controls in this section. Next, we discuss statistical analysis methods used in microbiome research, focusing on problems with multiple comparisons and ways to compare β-diversity between groups. Finally, we provide step-by-step pipelines for bioinformatics analysis. In summary, the meticulous study design is a key step to obtaining meaningful results, and appropriate statistical methods are important for accurate interpretation of microbiome data. The step-by-step pipelines provide researchers with insights into newly developed bioinformatics analysis methods.

Changes of gut microbiome composition and metabolites associated with hypertensive heart failure rats

Background

The potential role of the gut microbiome (GM) in heart failure (HF) had recently been revealed. However, the underlying mechanisms of the GM and fecal metabolome in HF have not been characterized. The Dahl salt-sensitive rat model of hypertensive heart failure (H-HF) was used to study the clinical symptoms and characteristics. To elucidate the pathogenesis of HF, we combined 16S rRNA gene sequencing and metabolomics to analyze gut microbial compositions and fecal metabolomic profiles of rats with H-HF.

Results

PCoA of beta diversity shown that the gut microbiome composition profiles among the three groups were separated. Gut microbial composition was significantly altered in H-HF rats, the ratio of Firmicutes to Bacteroidetes(F/B) increased and the abundance of Muribaculaceae, Lachnospiraceae, and Lactobacillaceae decreased. Significantly altered levels of 17 genera and 35 metabolites were identified as the potential biomarker of H-HF. Correlation analysis revealed that specific altered genera were strongly correlated with changed fecal metabolites. The reduction in short-chain fatty acids (SCFA)-producing bacteria and trimethylamine N-oxide (TMAO) might be a notable characteristic for H-HF.

Conclusions

This is the first study to characterize the fecal microbiome of hypertensive heart failure by integrating 16S rRNA gene sequencing and LC–MS-based metabolomics approaches. Collectively, the results suggesting changes of gut microbiome composition and metabolites are associated with hypertensive heart failure rats.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-021-02202-5.

Exploring the Potential Role of the Gut Microbiome in Chemotherapy-Induced Neurocognitive Disorders and Cardiovascular Toxicity

Chemotherapy, targeting not only malignant but also healthy cells, causes many undesirable side effects in cancer patients. Due to this fact, long-term cancer survivors often suffer from late effects, including cognitive impairment and cardiovascular toxicity. Chemotherapy damages the intestinal mucosa and heavily disrupts the gut ecosystem, leading to gastrointestinal toxicity. Animal models and clinical studies have revealed the associations between intestinal dysbiosis and depression, anxiety, pain, impaired cognitive functions, and cardiovascular diseases. Recently, a possible link between chemotherapy-induced gut microbiota disruption and late effects in cancer survivors has been proposed. In this review, we summarize the current understanding of preclinical and clinical findings regarding the emerging role of the microbiome and the microbiota-gut-brain axis in chemotherapy-related late effects affecting the central nervous system (CNS) and heart functions. Importantly, we provide an overview of clinical trials evaluating the relationship between the gut microbiome and cancer survivorship. Moreover, the beneficial effects of probiotics in experimental models and non-cancer patients with neurocognitive disorders and cardiovascular diseases as well as several studies on microbiota modulations via probiotics or fecal microbiota transplantation in cancer patients are discussed.

Gut Microbiota Metabolism and Interaction with Food Components

The human gut contains trillions of microbes that play a central role in host biology, including the provision of key nutrients from the diet. Food is a major source of precursors for metabolite production; in fact, diet modulates the gut microbiota (GM) as the nutrients, derived from dietary intake, reach the GM, affecting both the ecosystem and microbial metabolic profile. GM metabolic ability has an impact on human nutritional status from childhood. However, there is a wide variability of dietary patterns that exist among individuals. The study of interactions with the host via GM metabolic pathways is an interesting field of research in medicine, as microbiota members produce myriads of molecules with many bioactive properties. Indeed, much evidence has demonstrated the importance of metabolites produced by the bacterial metabolism from foods at the gut level that dynamically participate in various biochemical mechanisms of a cell as a reaction to environmental stimuli. Hence, the GM modulate homeostasis at the gut level, and the alteration in their composition can concur in disease onset or progression, including immunological, inflammatory, and metabolic disorders, as well as cancer. Understanding the gut microbe–nutrient interactions will increase our knowledge of how diet affects host health and disease, thus enabling personalized therapeutics and nutrition.