The Gut Microbiome of Heart Failure With Preserved Ejection Fraction

The gut-immune axis during hypertension and cardiovascular diseases

The gut-immune axis is a relatively novel phenomenon that provides mechanistic links between the gut microbiome and the immune system. A growing body of evidence supports it is key in how the gut microbiome contributes to several diseases, including hypertension and cardiovascular diseases (CVDs). Evidence over the past decade supports a causal link of the gut microbiome in hypertension and its complications, including myocardial infarction, atherosclerosis, heart failure, and stroke. Perturbations in gut homeostasis such as dysbiosis (i.e., alterations in gut microbial composition) may trigger immune responses that lead to chronic low-grade inflammation and, ultimately, the development and progression of these conditions. This is unsurprising, as the gut harbors one of the largest numbers of immune cells in the body, yet is a phenomenon not entirely understood in the context of cardiometabolic disorders. In this review, we discuss the role of the gut microbiome, the immune system, and inflammation in the context of hypertension and CVD, and consolidate current evidence of this complex interplay, whilst highlighting gaps in the literature. We focus on diet as one of the major modulators of the gut microbiota, and explain key microbial-derived metabolites (e.g., short-chain fatty acids, trimethylamine N-oxide) as potential mediators of the communication between the gut and peripheral organs such as the heart, arteries, kidneys, and the brain via the immune system. Finally, we explore the dual role of both the gut microbiome and the immune system, and how they work together to not only contribute, but also mitigate hypertension and CVD.

Gut microbiota, blood metabolites, and left ventricular diastolic dysfunction in US Hispanics/Latinos

BACKGROUND

Left ventricular diastolic dysfunction (LVDD) is an important precursor of heart failure (HF), but little is known about its relationship with gut dysbiosis and microbial-related metabolites. By leveraging the multi-omics data from the Hispanic Community Health Study/Study of Latinos (HCHS/SOL), a study with population at high burden of LVDD, we aimed to characterize gut microbiota associated with LVDD and identify metabolite signatures of gut dysbiosis and incident LVDD.

RESULTS

We included up to 1996 Hispanic/Latino adults (mean age: 59.4 years; 67.1% female) with comprehensive echocardiography assessments, gut microbiome, and blood metabolome data. LVDD was defined through a composite criterion involving tissue Doppler assessment and left atrial volume index measurements. Among 1996 participants, 916 (45.9%) had prevalent LVDD, and 212 out of 594 participants without LVDD at baseline developed incident LVDD over a median 4.3 years of follow-up. Using multivariable-adjusted analysis of compositions of microbiomes (ANCOM-II) method, we identified 7 out of 512 dominant gut bacterial species (prevalence > 20%) associated with prevalent LVDD (FDR-q < 0.1), with inverse associations being found for Intestinimonas_massiliensis, Clostridium_phoceensis, and Bacteroide_coprocola and positive associations for Gardnerella_vaginali, Acidaminococcus_fermentans, Pseudomonas_aeruginosa, and Necropsobacter_massiliensis. Using multivariable adjusted linear regression, 220 out of 669 circulating metabolites with detection rate > 75% were associated with the identified LVDD-related bacterial species (FDR-q < 0.1), with the majority being linked to Intestinimonas_massiliensis, Clostridium_phoceensis, and Acidaminococcus_fermentans. Furthermore, 46 of these bacteria-associated metabolites, mostly glycerophospholipids, secondary bile acids, and amino acids, were associated with prevalent LVDD (FDR-q < 0.1), 21 of which were associated with incident LVDD (relative risk ranging from 0.81 [p = 0.001, for guanidinoacetate] to 1.25 [p = 9 × 10-5, for 1-stearoyl-2-arachidonoyl-GPE (18:0/20:4)]). The inclusion of these 21 bacterial-related metabolites significantly improved the prediction of incident LVDD compared with a traditional risk factor model (the area under the receiver operating characteristic curve [AUC] = 0.73 vs 0.70, p = 0.001). Metabolite-based proxy association analyses revealed the inverse associations of Intestinimonas_massilliensis and Clostridium_phoceensis and the positive association of Acidaminococcus_fermentans with incident LVDD.

CONCLUSION

In this study of US Hispanics/Latinos, we identified multiple gut bacteria and related metabolites linked to LVDD, suggesting their potential roles in this preclinical HF entity. Video Abstract.

Heart failure-induced microbial dysbiosis contributes to colonic tumour formation in mice

AIMS

Heart failure (HF) and cancer are the leading causes of death worldwide. Epidemiological studies revealed that HF patients are prone to develop cancer. Preclinical studies provided some insights into this connection, but the exact mechanisms remain elusive. In colorectal cancer (CRC), gut microbial dysbiosis is linked to cancer progression and recent studies have shown that HF patients display microbial dysbiosis. This current study focussed on the effects of HF-induced microbial dysbiosis on colonic tumour formation.

METHODS AND RESULTS

C57BL/6J mice were subjected to myocardial infarction (MI), with sham surgery as control. After six weeks faeces were collected, processed for 16 s rRNA sequencing, and pooled for faecal microbiota transplantation. CRC tumour growth was provoked in germ-free mice by treating them with Azoxymethane/Dextran sodium sulphate. The CRC mice were transplanted with faeces from MI or sham mice. MI-induced HF resulted in microbial dysbiosis, characterized by a decreased α-diversity and microbial alterations on the genus level, several of which have been associated with CRC. We then performed faecal microbiota transplantation with faeces from HF mice in CRC mice, which resulted in a higher endoscopic disease score and an increase in the number of tumours in CRC mice.

CONCLUSION

We demonstrated that MI-induced HF contributes to colonic tumour formation by altering the gut microbiota composition, providing a mechanistic explanation for the observed association between HF and increased risk for cancer. Targeting the microbiome may present as a tool to mitigate HF-associated co-morbidities, especially cancer.

The Mediterranean Diet, Its Microbiome Connections, and Cardiovascular Health: A Narrative Review

The Mediterranean diet (MD), rich in minimally processed plant foods and in monounsaturated fats but low in saturated fats, meat, and dairy products, represents one of the most studied diets for cardiovascular health. It has been shown, from both observational and randomized controlled trials, that MD reduces body weight, improves cardiovascular disease surrogates such as waist-to-hip ratios, lipids, and inflammation markers, and even prevents the development of fatal and nonfatal cardiovascular disease, diabetes, obesity, and other diseases. However, it is unclear whether it offers cardiovascular benefits from its individual components or as a whole. Furthermore, limitations in the methodology of studies and meta-analyses have raised some concerns over its potential cardiovascular benefits. MD is also associated with characteristic changes in the intestinal microbiota, mediated through its constituents. These include increased growth of species producing short-chain fatty acids, such as Clostridium leptum and Eubacterium rectale, increased growth of Bifidobacteria, Bacteroides, and Faecalibacterium prausnitzii species, and reduced growth of Firmicutes and Blautia species. Such changes are known to be favorably associated with inflammation, oxidative status, and overall metabolic health. This review will focus on the effects of MD on cardiovascular health through its action on gut microbiota.

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.

Probiotics, gut microbiome, and cardiovascular diseases: An update

Cardiovascular diseases (CVD) are one of the most challenging diseases and many factors have been demonstrated to affect their pathogenesis. One of the major factors that affect CVDs, especially atherosclerosis, is the gut microbiota (GM). Genetics play a key role in linking CVDs with GM, in addition to some environmental factors which can be either beneficial or harmful. The interplay between GM and CVDs is complex due to the numerous mechanisms through which microbial components and their metabolites can influence CVDs. Within this interplay, the immune system plays a major role, mainly based on the immunomodulatory effects of microbial dysbiosis and its resulting metabolites. The resulting modulation of chronic inflammatory processes was found to reduce the severity of CVDs and to maintain cardiovascular health. To better understand the specific roles of GM-related metabolites in this interplay, this review presents an updated perspective on gut metabolites related effects on the cardiovascular system, highlighting the possible benefits of probiotics in therapeutic strategies.

Oral Cardiac Drug-Gut Microbiota Interaction in Chronic Heart Failure Patients: An Emerging Association

Regardless of the currently proposed best medical treatment for heart failure patients, the morbidity and mortality rates remain high. This is due to several reasons, including the interaction between oral cardiac drug administration and gut microbiota. The relation between drugs (especially antibiotics) and gut microbiota is well established, but it is also known that more than 24% of non-antibiotic drugs affect gut microbiota, altering the microbe's environment and its metabolic products. Heart failure treatment lies mainly in the blockage of neuro-humoral hyper-activation. There is debate as to whether the administration of heart-failure-specific drugs can totally block this hyper-activation, or whether the so-called intestinal dysbiosis that is commonly observed in this group of patients can affect their action. Although there are several reports indicating a strong relation between drug-gut microbiota interplay, little is known about this relation to oral cardiac drugs in chronic heart failure. In this review, we review the contemporary data on a topic that is in its infancy. We aim to produce scientific thoughts and questions and provide reasoning for further clinical investigation.

Gut microbiota and risk of endocarditis: a bidirectional Mendelian randomization study

Background

The associations between gut microbiota and cardiovascular disease have been reported in previous studies. However, the relationship between gut microbiota and endocarditis remains unclear.

Methods

A bidirectional Mendelian randomization (MR) study was performed to detect the association between gut microbiota and endocarditis. Inverse variance weighted (IVW) method was considered the main result. Simultaneously, heterogeneity and pleiotropy tests were conducted.

Results

Our study suggests that family Victivallaceae (p = 0.020), genus Eubacterium fissicatena group (p = 0.047), genus Escherichia Shigella (p = 0.024), genus Peptococcus (p = 0.028) and genus Sellimonas (p = 0.005) play protective roles in endocarditis. Two microbial taxa, including genus Blautia (p = 0.006) and genus Ruminococcus2 (p = 0.024) increase the risk of endocarditis. At the same time, endocarditis has a negative effect on genus Eubacterium fissicatena group (p = 0.048). Besides, no heterogeneity or pleiotropy was found in this study.

Conclusion

Our study emphasized the certain role of specific gut microbiota in patients with endocarditis and clarified the negative effect of endocarditis on gut microbiota.

Association between reduced left ventricular ejection fraction and peritoneal dialysis related peritonitis: a single center retrospective cohort study in Japan

We present a single-center retrospective analysis of 228 Japanese patients with peritoneal dialysis, in which we examined whether reduced left ventricular ejection fraction (LVEF) is a risk factor for peritonitis development. Time-dependent multivariable-adjusted Cox proportional hazards models revealed that reduced LVEF (LVEF < 50% vs. preserved LVEF ≥ 50%, hazard ratio (HR) 2.10; 95% confidence interval (CI) 1.16-3.82) was associated with peritonitis. Qualitatively, similar associations with reduced LVEF (< 50%) were observed for enteric peritonitis (adjusted HR 7.68; 95% CI 2.51-23.5) but not for non-enteric peritonitis (adjusted HR 1.15; 95% CI 0.54-2.44). Reduced LVEF is associated with a significantly higher risk of subsequent peritonitis, particularly enteric peritonitis. These results indicate that patients with reduced LVEF may be at risk of enteric peritonitis from bowel sources caused by intestinal involvement due to cardiac dysfunction.

Effects of Gut Microbiota on Hypertension and the Cardiovascular System

Cardiovascular diseases, which include hypertension and atherosclerosis, are a group of disorders that affect the heart and blood vessels [...].

Exercise and microbiome: From big data to therapy

Exercise is a vital component in maintaining optimal health and serves as a prospective therapeutic intervention for various diseases. The human microbiome, comprised of trillions of microorganisms, plays a crucial role in overall health. Given the advancements in microbiome research, substantial databases have been created to decipher the functionality and mechanisms of the microbiome in health and disease contexts. This review presents an initial overview of microbiomics development and related databases, followed by an in-depth description of the multi-omics technologies for microbiome. It subsequently synthesizes the research pertaining to exercise-induced modifications of the microbiome and diseases that impact the microbiome. Finally, it highlights the potential therapeutic implications of an exercise-modulated microbiome in intestinal disease, obesity and diabetes, cardiovascular disease, and immune/inflammation-related diseases.

Microbiome-based risk prediction in incident heart failure: a community challenge

Heart failure (HF) is a major public health problem. Early identification of at-risk individuals could allow for interventions that reduce morbidity or mortality. The community-based FINRISK Microbiome DREAM challenge (synapse.org/finrisk) evaluated the use of machine learning approaches on shotgun metagenomics data obtained from fecal samples to predict incident HF risk over 15 years in a population cohort of 7231 Finnish adults (FINRISK 2002, n=559 incident HF cases). Challenge participants used synthetic data for model training and testing. Final models submitted by seven teams were evaluated in the real data. The two highest-scoring models were both based on Cox regression but used different feature selection approaches. We aggregated their predictions to create an ensemble model. Additionally, we refined the models after the DREAM challenge by eliminating phylum information. Models were also evaluated at intermediate timepoints and they predicted 10-year incident HF more accurately than models for 5- or 15-year incidence. We found that bacterial species, especially those linked to inflammation, are predictive of incident HF. This highlights the role of the gut microbiome as a potential driver of inflammation in HF pathophysiology. Our results provide insights into potential modeling strategies of microbiome data in prospective cohort studies. Overall, this study provides evidence that incorporating microbiome information into incident risk models can provide important biological insights into the pathogenesis of HF.

Gut-derived short-chain fatty acids bridge cardiac and systemic metabolism and immunity in heart failure

Heart failure (HF) represents a group of complex clinical syndromes with high morbidity and mortality and has a significant global health burden. Inflammation and metabolic disorders are closely related to the development of HF, which are complex and depend on the severity and type of HF and common metabolic comorbidities such as obesity and diabetes. An increasing body of evidence indicates the importance of short-chain fatty acids (SCFAs) in regulating cardiac function. In addition, SCFAs represent a unique class of metabolites and play a distinct role in shaping systemic immunity and metabolism. In this review, we reveal the role of SCFAs as a link between metabolism and immunity, which regulate cardiac and systemic immune and metabolic systems by acting as energy substrates, inhibiting the expression of histone deacetylase (HDAC) regulated genes and activating G protein-coupled receptors (GPCRs) signaling. Ultimately cardiac efficiency is improved, cardiac inflammation alleviated and cardiac function in failing hearts enhanced. In conclusion, SCFAs represent a new therapeutic approach for HF.

Akkermansia muciniphila participates in the host protection against helminth-induced cardiac fibrosis via TLR2

Helminth Trichinella spiralis (Ts) is one of the major pathogens of human infective myocarditis that can lead to cardiac fibrosis (CF). The gut microbiota involved in this pathology are of interest. Here, we use mice infected with Ts as a model to examine the interactions between gut microbes and host protection to CF. Infected mice show enhanced CF severity. We find that antibiotics treatment to deplete the microbiota aggravates the disease phenotype. Attempts to restore microbiota using fecal microbiota transplantation ameliorates helminth-induced CF. 16S rRNA gene sequencing and metagenomics sequencing reveal a higher abundance of Akkermansia muciniphila in gut microbiomes of Ts-infected mice. Oral supplementation with alive or pasteurized A. muciniphila improves CF via TLR2. This work represents a substantial advance toward our understanding of causative rather than correlative relationships between the gut microbiota and CF.

Importance of gut microbiota metabolites in the development of cardiovascular diseases (CVD)

Cardiovascular disease (CVD) remains the most common cause of death worldwide and has become a public health concern. The proven notable risk factors for CVD are atherosclerosis, hypertension, diabetes, dyslipidemia, inflammation, and some genetic defects. However, research has shown a correlation between metabolic health, gut microbiota, and dietary risk factors. The gut microbiota makes an important contribution to human functional metabolic pathways by contributing enzymes that are not encoded by the human genome, for instance, the breakdown of polysaccharides, polyphenols and vitamins synthesis. TMAO and SCFAs, human gut microbiota compounds, have respective immunomodulatory and pro-inflammatory effects. Choline and l-carnitine are abundant in high-fat diets and are transformed into TMA by gut bacteria. The liver's phase of metabolism then changes TMA into TMAO. In turn, TMAO promotes the activation of macrophages, damages vascular endothelium, and results in CVD-however, dysbiosis decreases SCFAs and bile acids, which raises intestinal permeability. Congestion in the portal vein, a drop in cardiac output, a reduction in intestinal perfusion, and intestinal leakage are all caused by heart failure. These factors induce systemic inflammation by increasing intestinal leakage. By raising CRP and pro-inflammatory reactions, human gut dysbiosis and elevated TMAO levels promote the development of arterial plaque, hasten the beginning of atherosclerosis, and raise the risk of CAD. A healthy symbiosis between the gut microbiota and host is a key factor in shaping the biochemical profile of the diet, therefore which are crucial for maintaining the intestinal epithelial barrier, growing mucosa, reducing inflammation, and controlling blood pressure.

Gut Microbiota and Derived Short-Chain Fatty Acids Are Linked to Evolution of Heart Failure Patients

There is a lack of direct evidence regarding gut microbiota dysbiosis and changes in short-chain fatty acids (SCFAs) in heart failure (HF) patients. We sought to assess any association between gut microbiota composition, SCFA production, clinical parameters, and the inflammatory profile in a cohort of newly diagnosed HF patients. In this longitudinal prospective study, we enrolled eighteen newly diagnosed HF patients. At admission and after 12 months, blood samples were collected for the assessment of proinflammatory cytokines, monocyte populations, and endothelial dysfunction, and stool samples were collected for analysis of gut microbiota composition and quantification of SCFAs. Twelve months after the initial HF episode, patients demonstrated improved clinical parameters and reduced inflammatory state and endothelial dysfunction. This favorable evolution was associated with a reversal of microbiota dysbiosis, consisting of the increment of health-related bacteria, such as genus Bifidobacterium, and levels of SCFAs, mainly butyrate. Furthermore, there was a decrease in the abundance of pathogenic bacteria. In vitro, fecal samples collected after 12 months of follow-up exhibited lower inflammation than samples collected at admission. In conclusion, the favorable progression of HF patients after the initial episode was linked to the reversal of gut microbiota dysbiosis and increased SCFA production, particularly butyrate. Whether restoring butyrate levels or promoting the growth of butyrate-producing bacteria could serve as a complementary treatment for these patients deserves further studies.

Causal relationships between the gut microbiome, blood lipids, and heart failure: a Mendelian randomization analysis

AIMS

Studies have linked gut microbiome and heart failure (HF). However, their causal relationships and potential mediating factors have not been well defined. To investigate the causal relationships between the gut microbiome and HF and the mediating effect of potential blood lipids by using genetics.

METHODS AND RESULTS

We performed a bidirectional and mediation Mendelian randomization (MR) study using summary statistics from the genome-wide association studies of gut microbial taxa (Dutch Microbiome Project, n = 7738), blood lipids (UK Biobank, n = 115 078), and a meta-analysis of HF (115 150 cases and 1550 331 controls). We applied the inverse-variance weighted estimation method as the primary method, with several other estimators as complementary methods. The multivariable MR approach based on Bayesian model averaging (MR-BMA) was used to prioritize the most likely causal lipids. Six microbial taxa are suggestively associated with HF causally. The most significant taxon was the species Bacteroides dorei [odds ratio = 1.059, 95% confidence interval (CI) = 1.022-1.097, P-value = 0.0017]. The MR-BMA analysis showed that apolipoprotein B (ApoB) was the most likely causal lipid for HF (the marginal inclusion probability = 0.717, P-value = 0.005). The mediation MR analysis showed that ApoB mediated the causal effects of species B. dorei on HF (proportion mediated = 10.1%, 95% CI = 0.2-21.6%, P-value = 0.031).

CONCLUSION

The study suggested a causal relationship between specific gut microbial taxa and HF and that ApoB might mediate this relationship as the primary lipid determinant of HF.

Gut Microbiota and Microbial Metabolism in Early Risk of Cardiometabolic Disease

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

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.

Effects of Empagliflozin on Gut Microbiota in Heart Failure with a Preserved Ejection Fraction: The Design of a Pragmatic Randomized, Open-Label Controlled Trial (EMPAGUM)

Although empagliflozin has been recommended for individuals with heart failure, its effects on heart failure with preserved ejection fraction (HFpEF) remain uncertain from a physiopathological standpoint. The metabolites produced by gut microbiota have been shown to have a crucial role in the development of heart failure. Sodium-glucose cotransporter-2 inhibitors (SGLT2) have been shown to change the make-up of the gut microbiota in rodent studies. There is mixed evidence from similar studies investigating whether or not SGLT2 can affect the microbiota in the human gut. This trial is a pragmatic, randomized, open-label controlled study with empagliflozin as an intervention. We will enroll 100 patients with HFpEF and randomly assign them to one of two groups to receive either empagliflozin or a placebo. Patients in the Empagliflozin group will be given 10 mg of the drug daily, while those in the Control group will not be given empagliflozin or any other SGLT2. The purpose of the trial is to validate the changes that occur in gut microbiota in patients with HFpEF who take empagliflozin and to investigate the function of gut microbiota and their metabolites in the process.

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.

Gut Failure: A Review of the Pathophysiology and Therapeutic Potentials in the Gut-Heart Axis

Despite considerable advances in the field, heart failure (HF) still poses a significant disease burden among affected individuals since it continues to cause high morbidity and mortality rates. Inflammation is considered to play a key role in disease progression, but the exact underlying pathophysiological mechanisms involved have not yet been fully elucidated. The gut, as a potential source of inflammation, could feasibly explain the state of low-grade inflammation seen in patients with chronic HF. Several derangements in the composition of the microbiota population, coupled with an imbalance between favorable and harmful metabolites and followed by gut barrier disruption and eventually bacterial translocation, could contribute to cardiac dysfunction and aggravate HF. On the other hand, HF-associated congestion and hypoperfusion alters intestinal function, thereby creating a vicious cycle. Based on this evidence, novel pharmaceutical agents have been developed and their potential therapeutic use has been tested in both animal and human subjects. The ultimate goal in these efforts is to reverse the aforementioned intestinal derangements and block the inflammation cascade. This review summarizes the gut-related causative pathways implicated in HF pathophysiology, as well as the associated therapeutic interventions described in the literature.

Microbiota and Cardiovascular Diseases: Mechanisms of Influence and Correction Possibilities

The term "microbiota"  refers to the microbial  community  occupying a specific  habitat  with  defined  physical  and  chemical  properties  and  forming specific  ecological  niches.  The adult  intestinal  microbiota  is diverse.  It mainly  consists  of bacteria  of Bacteroidetes  and  Firmicutes  types.  The link between the gut microbiota  and cardiovascular disease (CVD) is being actively discussed.  Rapid progress  in this field is explained  by the development of new generation  sequencing methods and the use of sterile gut mice in experiments.  More and more data are being published about the influence of microbiota  on the development  and course of hypertension, coronary  heart disease (IHD), myocardial  hypertrophy, chronic heart failure (CHF) and atrial fibrillation (AF). Diet therapy,  antibacterial drugs,  pro- and prebiotics are successfully  used as tools to correct the structure of the gut microbiota of the macroorganism. Correction  of gut microbiota  in an experiment  on rats with coronary  occlusion  demonstrates  a significant  reduction in necrotic area. A study  involving  patients  suffering  from  CHF  reveals a significant  reduction  in the level of uric acid,  highly  sensitive C-reactive protein,  and creatinine. In addition to structural and laboratory changes  in patients with CVD when modifying the microbiota  of the gut, also revealed the effect on the course of arterial hypertension. Correction  of gut microbiota  has a beneficial  effect on the course of AF. We assume  that further active study of issues of influence and interaction of gut microbiota  and macroorganism may in the foreseeable future make significant  adjustments  in approaches to treatment of such patients.

Oral and gut microbiome alterations in heart failure: Epidemiology, pathogenesis and response to advanced heart failure therapies

Despite significant advances in therapies, heart failure (HF) remains a progressive disease that, once advanced, is associated with significant death and disability. Cardiac replacement therapies with left ventricular assist device (LVAD) and heart transplantation (HT) are the only treatment options for advanced HF, while lifesaving they can also be lifespan limiting due to the associated complications. Systemic inflammation is mechanistically important in HF pathophysiology and progression. However, directly targeting inflammation in HF has not been beneficial thus far. These failed attempts at therapeutics might be related to our limited understanding of the factors that cause inflammation in HF, and, therefore, to our inability to investigate these triggers in interventional studies. Observational studies have consistently demonstrated associations between alterations in the digestive (gut and oral) microbiome, inflammation and HF risk and progression. Additionally, recent data indicate that these microbial perturbations persist following LVAD and HT, along with residual inflammation and oxidative stress. Furthermore, there is rising recognition of the critical contribution of the microbiome to the metabolism of immunosuppressive drugs after HT. Cumulatively, these findings might posit a mechanistic link between microbiome alterations, systemic inflammation, and adverse outcomes in HF patients before and after cardiac replacement therapies. This review (1) provides an update on available data linking changes in digestive tract microbiota, inflammation, and oxidative stress, to HF pathogenesis and progression; (2) describes evolution of these relationships following LVAD and HT; and (3) outlines present and future intervention strategies that can manipulate the microbiome and possibly modify HF disease trajectory.

The gut microbiome and hypertension

A large body of evidence has emerged in the past decade supporting a role for the gut microbiome in the regulation of blood pressure. The field has moved from association to causation in the last 5 years, with studies that have used germ-free animals, antibiotic treatments and direct supplementation with microbial metabolites. The gut microbiome can regulate blood pressure through several mechanisms, including through gut dysbiosis-induced changes in microbiome-associated gene pathways in the host. Microbiota-derived metabolites are either beneficial (for example, short-chain fatty acids and indole-3-lactic acid) or detrimental (for example, trimethylamine N-oxide), and can activate several downstream signalling pathways via G protein-coupled receptors or through direct immune cell activation. Moreover, dysbiosis-associated breakdown of the gut epithelial barrier can elicit systemic inflammation and disrupt intestinal mechanotransduction. These alterations activate mechanisms that are traditionally associated with blood pressure regulation, such as the renin-angiotensin-aldosterone system, the autonomic nervous system, and the immune system. Several methodological and technological challenges remain in gut microbiome research, and the solutions involve minimizing confounding factors, establishing causality and acting globally to improve sample diversity. New clinical trials, precision microbiome medicine and computational methods such as Mendelian randomization have the potential to enable leveraging of the microbiome for translational applications to lower blood pressure.

Diet-Induced Microbiome's Impact on Heart Failure: A Double-Edged Sword

Heart failure (HF) is a debilitating disease with a significant clinical and economic impact worldwide. Multiple factors seem to increase the risk of developing HF, such as hypertension, obesity and diabetes. Since chronic inflammation plays a significant role in HF pathophysiology and gut dysbiosis is associated with low-grade chronic inflammation, the risk of cardiovascular diseases is likely modulated by the gut microbiome (GM). Considerable progress has been made in HF management. However, there is a need to find new strategies to reduce mortality and increase the quality of life, mainly of HFpEF patients, since its prevalence continues to rise. Recent studies validate that lifestyle changes, such as diet modulation, represent a potential therapeutic approach to improve several cardiometabolic diseases, although their effects on the GM and its indirect cardiac impact still warrant further research. Hence, in this paper, we aim to clarify the link between HF and the human microbiome.

Cardiac metabolism in HFpEF: from fuel to signalling

Heart failure (HF) is marked by distinctive changes in myocardial uptake and utilization of energy substrates. Among the different types of HF, HF with preserved ejection fraction (HFpEF) is a highly prevalent, complex, and heterogeneous condition for which metabolic derangements seem to dictate disease progression. Changes in intermediate metabolism in cardiometabolic HFpEF-among the most prevalent forms of HFpEF-have a large impact both on energy provision and on a number of signalling pathways in the heart. This dual, metabolic vs. signalling, role is played in particular by long-chain fatty acids (LCFAs) and short-chain carbon sources [namely, short-chain fatty acids (SCFAs) and ketone bodies (KBs)]. LCFAs are key fuels for the heart, but their excess can be harmful, as in the case of toxic accumulation of lipid by-products (i.e. lipotoxicity). SCFAs and KBs have been proposed as a potential major, alternative source of energy in HFpEF. At the same time, both LCFAs and short-chain carbon sources are substrate for protein post-translational modifications and other forms of direct and indirect signalling of pivotal importance in HFpEF pathogenesis. An in-depth molecular understanding of the biological functions of energy substrates and their signalling role will be instrumental in the development of novel therapeutic approaches to HFpEF. Here, we summarize the current evidence on changes in energy metabolism in HFpEF, discuss the signalling role of intermediate metabolites through, at least in part, their fate as substrates for post-translational modifications, and highlight clinical and translational challenges around metabolic therapy in HFpEF.

The Interaction of Gut Microbiota and Heart Failure with Preserved Ejection Fraction: From Mechanism to Potential Therapies

Heart failure with preserved ejection fraction (HFpEF) is a disease for which there is no definite and effective treatment, and the number of patients is more than 50% of heart failure (HF) patients. Gut microbiota (GMB) is a general term for a group of microbiota living in humans' intestinal tracts, which has been proved to be related to cardiovascular diseases, including HFpEF. In HFpEF patients, the composition of GMB is significantly changed, and there has been a tendency toward dysbacteriosis. Metabolites of GMB, such as trimethylamine N-oxide (TMAO), short-chain fatty acids (SCFAs) and bile acids (BAs) mediate various pathophysiological mechanisms of HFpEF. GMB is a crucial influential factor in inflammation, which is considered to be one of the main causes of HFpEF. The role of GMB in its important comorbidity-metabolic syndrome-also mediates HFpEF. Moreover, HF would aggravate intestinal barrier impairment and microbial translocation, further promoting the disease progression. In view of these mechanisms, drugs targeting GMB may be one of the effective ways to treat HFpEF. This review focuses on the interaction of GMB and HFpEF and analyzes potential therapies.

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.

The Role of Intestinal Flora and Its Metabolites in Heart Failure

Intestinal flora is a complex collection of microbial communities that participate in the physiological and pathological activities of the human body through various pathways. In recent years, numerous studies have reported that intestinal flora are involved in the occurrence and development of heart failure (HF) and its metabolic products could play an important role in this progression, suggesting a great value in the clinical treatment of this condition. This study reported the interaction between intestinal flora and HF, and with intestinal flora metabolites, such as short-chain fatty acids, trimethylamine N-oxide and bile acids and urotoxins, considered as the starting point, the mechanism of the roles in HF was summarized. Additionally, the current research status and the development prospects of applying flora and metabolites to the clinical therapeutic decision of HF were discussed.

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.

Gut Microbiota-Generated Phenylacetylglutamine and Heart Failure

BACKGROUND

The gut microbiota-dependent metabolite phenylacetylgutamine (PAGln) is both associated with atherothrombotic heart disease in humans, and mechanistically linked to cardiovascular disease pathogenesis in animal models via modulation of adrenergic receptor signaling.

METHODS

Here we examined both clinical and mechanistic relationships between PAGln and heart failure (HF). First, we examined associations among plasma levels of PAGln and HF, left ventricular ejection fraction, and N-terminal pro-B-type natriuretic peptide in 2 independent clinical cohorts of subjects undergoing coronary angiography in tertiary referral centers (an initial discovery US Cohort, n=3256; and a validation European Cohort, n=829). Then, the impact of PAGln on cardiovascular phenotypes relevant to HF in cultured cardiomyoblasts, and in vivo were also examined.

RESULTS

Circulating PAGln levels were dose-dependently associated with HF presence and indices of severity (reduced ventricular ejection fraction, elevated N-terminal pro-B-type natriuretic peptide) independent of traditional risk factors and renal function in both cohorts. Beyond these clinical associations, mechanistic studies showed both PAGln and its murine counterpart, phenylacetylglycine, directly fostered HF-relevant phenotypes, including decreased cardiomyocyte sarcomere contraction, and B-type natriuretic peptide gene expression in both cultured cardiomyoblasts and murine atrial tissue.

CONCLUSIONS

The present study reveals the gut microbial metabolite PAGln is clinically and mechanistically linked to HF presence and severity. Modulating the gut microbiome, in general, and PAGln production, in particular, may represent a potential therapeutic target for modulating HF.

REGISTRATION

URL: https://clinicaltrials.gov/; Unique identifier: NCT00590200 and URL: https://drks.de/drks_web/; Unique identifier: DRKS00020915.

Fecal microbiome transplantation and tributyrin improves early cardiac dysfunction and modifies the BCAA metabolic pathway in a diet induced pre-HFpEF mouse model

More than 50% of patients with heart failure present with heart failure with preserved ejection fraction (HFpEF), and 80% of them are overweight or obese. In this study we developed an obesity associated pre-HFpEF mouse model and showed an improvement in both systolic and diastolic early dysfunction following fecal microbiome transplant (FMT). Our study suggests that the gut microbiome-derived short-chain fatty acid butyrate plays a significant role in this improvement. Cardiac RNAseq analysis showed butyrate to significantly upregulate ppm1k gene that encodes protein phosphatase 2Cm (PP2Cm) which dephosphorylates and activates branched-chain α-keto acid dehydrogenase (BCKDH) enzyme, and in turn increases the catabolism of branched chain amino acids (BCAAs). Following both FMT and butyrate treatment, the level of inactive p-BCKDH in the heart was reduced. These findings show that gut microbiome modulation can alleviate early cardiac mechanics dysfunction seen in the development of obesity associated HFpEF.

Clostridium butyricum and Bifidobacterium pseudolongum Attenuate the Development of Cardiac Fibrosis in Mice

Cardiac fibrosis is an integral aspect of every form of cardiovascular diseases, which is one of the leading causes of death worldwide. It is urgent to explore new effective drugs and treatments. In this paper, transverse aortic constriction (TAC)-induced cardiac fibrosis was significantly alleviated by a cocktail of antibiotics to clear the intestinal flora, indicating that the gut microbiota was associated with the disease process of cardiac fibrosis. We transplanted feces from sham-operated and TAC-treated mice to mice treated with a cocktail of antibiotics. We found that TAC-treated gut microbiota dysbiosis cannot cause cardiac fibrosis on its own. Interestingly, healthy fecal microbiota transplantation could alleviate cardiac fibrosis, indicating that targeted probiotics and related metabolite intervention may restore a normal microenvironment for the treatment or prevention of cardiac fibrosis. We used 16S rRNA sequencing of fecal samples and discovered that butyric acid-producing bacteria and Bifidobacterium pseudolongum were the dominant bacteria in the group with the lowest degree of cardiac fibrosis. Moreover, we demonstrated that sodium butyrate prevented the development of cardiac fibrosis. The effect of Clostridium butyricum (butyric acid-producing bacteria) was better than that of B. pseudolongum on cardiac fibrosis. Surprisingly, the cocktail of two probiotics had a stronger ability than a single probiotic. In conclusion, therapies targeting the gut microbiota and metabolites such as probiotics present new strategies for treating cardiovascular disease. IMPORTANCE Cardiac fibrosis is a basic process in cardiac remodeling. It is related to almost all types of cardiovascular diseases (CVD) and has become an important global health problem. Basic research and a number of clinical studies have shown that myocardial fibrosis can be prevented and reversed to a certain extent. It is urgent to explore new effective drugs and treatments. We indicated a causal relationship between cardiac fibrosis and gut microbiota. Gut microbiota dysbiosis cannot cause cardiac fibrosis on its own. Interestingly, healthy fecal microbiota transplantation could alleviate cardiac fibrosis. According to our findings, the combined use of butyric acid-producing bacteria and B. pseudolongum can help prevent cardiac fibrosis. Therapies targeting the gut microbiota and metabolites, such as probiotics, represent new strategies for treating cardiovascular disease.

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

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

Diversities in the Gut Microbial Patterns in Patients with Atherosclerotic Cardiovascular Diseases and Certain Heart Failure Phenotypes

To continue progress in the treatment of cardiovascular disease, there is a need to improve the overall understanding of the processes that contribute to the pathogenesis of cardiovascular disease (CVD). Exploring the role of gut microbiota in various heart diseases is a topic of great interest since it is not so easy to find such reliable connections despite the fact that microbiota undoubtedly affect all body systems. The present study was conducted to investigate the composition of gut microbiota in patients with atherosclerotic cardiovascular disease (ASCVD) and heart failure syndromes with reduced ejection fraction (HFrEF) and HF with preserved EF (HFpEF), and to compare these results with the microbiota of individuals without those diseases (control group). Fecal microbiota were evaluated by three methods: living organisms were determined using bacterial cultures, total DNA taxonomic composition was estimated by next generation sequencing (NGS) of 16S rRNA gene (V3-V4) and quantitative assessment of several taxa was performed using qPCR (quantitative polymerase chain reaction). Regarding the bacterial culture method, all disease groups demonstrated a decrease in abundance of Enterococcus faecium and Enterococcus faecalis in comparison to the control group. The HFrEF group was characterized by an increased abundance of Streptococcus sanguinus and Streptococcus parasanguinis. NGS analysis was conducted at the family level. No significant differences between patient's groups were observed in alpha-diversity indices (Shannon, Faith, Pielou, Chao1, Simpson, and Strong) with the exception of the Faith index for the HFrEF and control groups. Erysipelotrichaceae were significantly increased in all three groups; Streptococcaceae and Lactobacillaceae were significantly increased in ASCVD and HFrEF groups. These observations were indirectly confirmed with the culture method: two species of Streptococcus were significantly increased in the HFrEF group and Lactobacillus plantarum was significantly increased in the ASCVD group. The latter observation was also confirmed with qPCR of Lactobacillus sp. Acidaminococcaceae and Odoribacteraceae were significantly decreased in the ASCVD and HFrEF groups. Participants from the HFpEF group showed the least difference compared to the control group in all three study methods. The patterns found expand the knowledge base on possible correlations of gut microbiota with cardiovascular diseases. The similarities and differences in conclusions obtained by the three methods of this study demonstrate the need for a comprehensive approach to the analysis of microbiota.

Significance of Gut Microbiota and Short-Chain Fatty Acids in Heart Failure

Heart failure (HF), as the terminal stage of various heart diseases, seriously threatens an individual’s life, health, and quality of life. Emerging evidence has shown that the gut microbiota comprises an important component of human physiology and metabolic homeostasis, and can directly or indirectly affect the metabolic health of the host through metabolites. Upon in-depth study of intestinal microecology, the “gut-heart axis” appears to provide a novel direction for HF research. Thus, this review primarily focuses on the relationship between the gut microbiota and its major metabolites—i.e., short-chain fatty acids (SCFAs)—and HF. It explores the mechanisms underlying HF and its effective treatment by targeting SCFAs to optimize current HF treatment and thus improve the quality of patients’ lives.

Mechanisms shared between cancer, heart failure, and targeted anti-cancer therapies

Heart failure (HF) and cancer are the leading causes of death worldwide and accumulating evidence demonstrates that HF and cancer affect one another in a bidirectional way. Patients with HF are at increased risk for developing cancer, and HF is associated with accelerated tumour growth. The presence of malignancy may induce systemic metabolic, inflammatory, and microbial alterations resulting in impaired cardiac function. In addition to pathophysiologic mechanisms that are shared between cancer and HF, overlaps also exist between pathways required for normal cardiac physiology and for tumour growth. Therefore, these overlaps may also explain the increased risk for cardiotoxicity and HF as a result of targeted anti-cancer therapies. This review provides an overview of mechanisms involved in the bidirectional connection between HF and cancer, specifically focusing upon current 'hot-topics' in these shared mechanisms. It subsequently describes targeted anti-cancer therapies with cardiotoxic potential as a result of overlap between their anti-cancer targets and pathways required for normal cardiac function.

Gut Microbiota and Coronary Plaque Characteristics

Background The relationship between gut microbiota and in vivo coronary plaque characteristics has not been reported. This study was conducted to investigate the relationship between gut microbiota and coronary plaque characteristics in patients with coronary artery disease. Methods and Results Patients who underwent both optical coherence tomography and intravascular ultrasound imaging and provided stool and blood specimens were included. The composition of gut microbiota was evaluated using 16S rRNA sequencing. A total of 55 patients were included. At the genus level, 2 bacteria were associated with the presence of thin-cap fibroatheroma, and 9 bacteria were associated with smaller fibrous cap thickness. Among them, some bacteria had significant associations with inflammatory/prothrombotic biomarkers. Dysgonomonas had a positive correlation with interleukin-6, Paraprevotella had a positive correlation with fibrinogen and negative correlation with high-density lipoprotein cholesterol, Succinatimonas had positive correlations with fibrinogen and homocysteine, and Bacillus had positive correlations with fibrinogen and high-sensitivity C-reactive protein. In addition, Paraprevotella, Succinatimonas, and Bacillus were also associated with greater plaque volume. Ten bacteria were associated with larger fibrous cap thickness. Some were associated with protective biomarker changes; Anaerostipes had negative correlations with trimethylamine N-oxide, tumor necrosis factor α, and interleukin-6, and Dielma had negative correlations with trimethylamine N-oxide, white blood cells, plasminogen activator inhibitor-1, and homocysteine, and a positive correlation with high-density lipoprotein cholesterol. Conclusions Bacteria that were associated with vulnerable coronary plaque phenotype and greater plaque burden were identified. These bacteria were also associated with elevated inflammatory or prothrombotic biomarkers. Registration URL: https://www.umin.ac.jp/ctr/; Unique identifier: UMIN000041692.

Microbial metabolites and heart failure: Friends or enemies?

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

Association Between the Gut Microbiome and Their Metabolites With Human Blood Pressure Variability

BACKGROUND

Blood pressure (BP) variability is an independent risk factor for cardiovascular events. Recent evidence supports a role for the gut microbiota in BP regulation. However, whether the gut microbiome is associated with BP variability is yet to be determined. Here, we aimed to investigate the interplay between the gut microbiome and their metabolites in relation to BP variability.

METHODS

Ambulatory BP monitoring was performed in 69 participants from Australia (55.1% women; mean±SD, 59.8±7.26 years; body mass index, 25.2±2.83 kg/m²). These data were used to determine nighttime dipping, morning BP surge (MBPS) and BP variability as SD. The gut microbiome was determined by 16S ribosomal RNA (rRNA) sequencing and metabolite levels by gas chromatography.

RESULTS

We identified specific taxa associated with systolic BP variability, nighttime dipping, and MBPS. Notably, Alistipesfinegoldii and Lactobacillus spp. were only present in participants within the normal ranges of BP variability, MBPS and dipping, while Prevotella spp. and Clostridium spp., were found to be present in extreme dippers and the highest quartiles of BP SD and MBPS. There was a negative association between MBPS and microbial α-diversity (r=-0.244, P=0.046). MBPS was also negatively associated with plasma levels of microbial metabolites called short-chain fatty acids (r=-0.305, P=0.020), particularly acetate (r=-0.311, P=0.017).

CONCLUSIONS

Gut microbiome diversity, levels of microbial metabolites, and the bacteria Alistipesfinegoldii and Lactobacillus were associated with lower BP variability and Clostridium and Prevotella with higher BP variability. Thus, our findings suggest the gut microbiome and metabolites may be involved in the regulation of BP variability.

Understanding How Heart Metabolic Derangement Shows Differential Stage Specificity for Heart Failure with Preserved and Reduced Ejection Fraction

Heart failure (HF) is a clinical condition defined by structural and functional abnormalities in the heart that gradually result in reduced cardiac output (HFrEF) and/or increased cardiac pressures at rest and under stress (HFpEF). The presence of asymptomatic individuals hampers HF identification, resulting in delays in recognizing patients until heart dysfunction is manifested, thus increasing the chance of poor prognosis. Given the recent advances in metabolomics, in this review we dissect the main alterations occurring in the metabolic pathways behind the decrease in cardiac function caused by HF. Indeed, relevant preclinical and clinical research has been conducted on the metabolite connections and differences between HFpEF and HFrEF. Despite these promising results, it is crucial to note that, in addition to identifying single markers and reliable threshold levels within the healthy population, the introduction of composite panels would strongly help in the identification of those individuals with an increased HF risk. That said, additional research in the field is required to overcome the current drawbacks and shed light on the pathophysiological changes that lead to HF. Finally, greater collaborative data sharing, as well as standardization of procedures and approaches, would enhance this research field to fulfil its potential.

Gut microbiota in sarcopenia and heart failure

Sarcopenia is common in aging and in patients with heart failure (HF) who may experience worse outcomes. Patients with muscle wasting are more likely to experience falls and can have serious complications when undergoing cardiac procedures. While intensive nutritional support and exercise rehabilitation can help reverse some of these changes, they are often under-prescribed in a timely manner, and we have limited insights into who would benefit. Mechanistic links between gut microbial metabolites (GMM) have been identified and may contribute to adverse clinical outcomes in patients with cardio-renal diseases and aging. This review will examine the emerging evidence for the influence of the gut microbiome-derived metabolites and notable signaling pathways involved in both sarcopenia and HF, especially those linked to dietary intake and mitochondrial metabolism. This provides a unique opportunity to gain mechanistic and clinical insights into developing novel therapeutic strategies that target these GMM pathways or through tailored nutritional modulation to prevent progressive muscle wasting in elderly patients with heart failure.

The heart and gut relationship: a systematic review of the evaluation of the microbiome and trimethylamine-N-oxide (TMAO) in heart failure

There is an expanding body of research on the bidirectional relationship of the human gut microbiome and cardiovascular disease, including heart failure (HF). Researchers are examining the microbiome and gut metabolites, primarily trimethylamine-N-oxide (TMAO), to understand clinically observed outcomes. This systematic review explored the current state of the science on the evaluation and testing of the gut biome in persons with HF. Using electronic search methods of Medline, Embase, CINAHL, and Web of Science, until December 2021, we identified 511 HF biome investigations between 2014 and 2021. Of the 30 studies included in the review, six were 16S rRNA and nineteen TMAO, and three both TMAO and 16S rRNA, and two bacterial cultures. A limited range of study designs were represented, the majority involving single cohorts (n = 10) and comparing individuals with HF to controls (n = 15). Patients with HF had less biodiversity in fecal samples compared to controls. TMAO is associated with age, BNP, eGFR, HF severity, and poor outcomes including hospitalizations and mortality. Inconsistent across studies was the ability of TMAO to predict HF development, the independent prognostic value of TMAO when controlling for renal indices, and the relationship of TMAO to LVEF and CRP. Gut microbiome dysbiosis is associated with HF diagnosis, disease severity, and prognostication related to hospitalizations and mortality. Gut microbiome research in patients with HF is developing. Further longitudinal and multi-centered studies are required to inform interventions to promote clinical decision-making and improved patient outcomes.

Metformin and the heart: Update on mechanisms of cardiovascular protection with special reference to comorbid type 2 diabetes and heart failure

Metformin has been in clinical use for the management of type 2 diabetes for more than 60 years and is supported by a vast database of clinical experience: this includes evidence for cardioprotection from randomised trials and real-world studies. Recently, the position of metformin as first choice glucose-lowering agent has been supplanted to some extent by the emergence of newer classes of antidiabetic therapy, namely the sodium-glucose co-transporter-2 (SGLT2) inhibitors and glucagon-like peptide-1 (GLP-1) receptor agonists. These agents have benefitted through support from large cardiovascular outcomes trials with more modern trial designs than earlier studies conducted to assess metformin. Nevertheless, clinical research on metformin continues to further assess its many potentially advantageous effects. Here, we review the evidence for improved cardiovascular outcomes with metformin in the context of the current era of diabetes outcomes trials. Focus is directed towards the potentially cardioprotective actions of metformin in patients with type 2 diabetes and heart failure (HF), now recognised as the most common complication of diabetes.

Impact of the Gastrointestinal Tract Microbiota on Cardiovascular Health and Pathophysiology

ABSTRACT

The microbiota of the gastrointestinal tract (GIT) is an extremely diverse community of microorganisms, and their collective genomes (microbiome) provide a vast arsenal of biological activities, in particular enzymatic ones, which are far from being fully elucidated. The study of the microbiota (and the microbiome) is receiving great interest from the biomedical community as it carries the potential to improve risk-prediction models, refine primary and secondary prevention efforts, and also design more appropriate and personalized therapies, including pharmacological ones. A growing body of evidence, though sometimes impaired by the limited number of subjects involved in the studies, suggests that GIT dysbiosis, i.e. the altered microbial composition, has an important role in causing and/or worsening cardiovascular disease (CVD). Bacterial translocation as well as the alteration of levels of microbe-derived metabolites can thus be important to monitor and modulate, because they may lead to initiation and progression of CVD, as well as to its establishment as chronic state. We hereby aim to provide readers with details on available resources and experimental approaches that are used in this fascinating field of biomedical research, and on some novelties on the impact of GIT microbiota on CVD.

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.