Heart Failure Disturbs Gut-Blood Barrier and Increases Plasma Trimethylamine, a Toxic Bacterial Metabolite

Cardiovascular protective effects of natural flavonoids on intestinal barrier injury

Natural flavonoids may be utilized as an important therapy for cardiovascular diseases (CVDs) caused by intestinal barrier damage. More research is being conducted on the protective properties of natural flavonoids against intestinal barrier injury, although the underlying processes remain unknown. Thus, the purpose of this article is to present current research on natural flavonoids to reduce the incidence of CVDs by protecting intestinal barrier injury, with a particular emphasis on intestinal epithelial barrier integrity (inhibiting oxidative stress, regulating inflammatory cytokine expression, and increasing tight junction protein expression). Furthermore, the mechanisms driving intestinal barrier injury development are briefly explored, as well as natural flavonoids having CVD-protective actions on the intestinal barrier. In addition, natural flavonoids with myocardial protective effects were docked with ZO-1 targets to find natural products with higher activity. These natural flavonoids can improve intestinal mechanical barrier function through anti-oxidant or anti-inflammatory mechanism, and then prevent the occurrence and development of CVDs.

Impacts of intestinal microbiota metabolite trimethylamine N-oxide on cardiovascular disease: a bibliometric analysis

Background

Trimethylamine N-oxide (TMAO), a metabolite dependent on intestinal microbiota, is closely related to the emergence, progression, and prognosis of cardiovascular disease (CVD), and has received increasing attention in recent years.

Objective

The current research hotspots and future development trends in TMAO and CVD field are found through bibliometrics analysis, which provides reference for further study.

Methods

The bibliometrics tools VOSviewer and CiteSpace were used to analyze the publications from the Web of Science Core Collection (WOSCC) database. The articles published from 2004 to 2024 about the relationship between TMAO and CVD were retrieved. Bibliometric analysis includes annual publications, countries/regions, institutions, authors and co-cited authors, journals and cited-journals, references and keywords.

Results

After searching and screening, 1,466 publications were included for subsequent bibliometric analysis. Since 2014, the number of publications exposing the relationship between TMAO and CVD has increased rapidly, as has the frequency of citations. China, USA and Italy are the countries that publish the most relevant research. Cleveland Clinic is the leading institution in this field. Stanley L Hazen, Zeneng Wang and W H Wilson Tang are the most prolific authors in this field, and the latter two have the closest academic cooperation. American Journal of Clinical Nutrition and Journal of the American Heart Association are influential journals that publish research in this field. "Gut Microbial Metabolite TMAO Enhances Platelet Hyperreactivity and Thrombosis Risk" is the most frequently cited article. Keyword analysis shows that gut microbiota, metabolism, phosphatidylcholine and atherosclerosis (AS) are the hotspots in this field.

Conclusion

This study summarizes the research situation of TMAO and CVD in the past 20 years, focusing on the effect of TMAO on pathogenesis of AS, predictive value of TMAO on CVD risk, and dietary and drug intervention for TMAO. Probiotics and natural products may be the research focus of preventing and treating CVD by intervening TMAO in the future.

Interactions between the gut microbiome, associated metabolites and the manifestation and progression of heart failure with preserved ejection fraction in ZSF1 rats

BACKGROUND

Heart failure with preserved ejection fraction (HFpEF) is associated with systemic inflammation, obesity, metabolic syndrome, and gut microbiome changes. Increased trimethylamine-N-oxide (TMAO) levels are predictive for mortality in HFpEF. The TMAO precursor trimethylamine (TMA) is synthesized by the intestinal microbiome, crosses the intestinal barrier and is metabolized to TMAO by hepatic flavin-containing monooxygenases (FMO). The intricate interactions of microbiome alterations and TMAO in relation to HFpEF manifestation and progression are analyzed here.

METHODS

Healthy lean (L-ZSF1, n = 12) and obese ZSF1 rats with HFpEF (O-ZSF1, n = 12) were studied. HFpEF was confirmed by transthoracic echocardiography, invasive hemodynamic measurements, and detection of N-terminal pro-brain natriuretic peptide (NT-proBNP). TMAO, carnitine, symmetric dimethylarginine (SDMA), and amino acids were measured using mass-spectrometry. The intestinal epithelial barrier was analyzed by immunohistochemistry, in-vitro impedance measurements and determination of plasma lipopolysaccharide via ELISA. Hepatic FMO3 quantity was determined by Western blot. The fecal microbiome at the age of 8, 13 and 20 weeks was assessed using 16s rRNA amplicon sequencing.

RESULTS

Increased levels of TMAO (+ 54%), carnitine (+ 46%) and the cardiac stress marker NT-proBNP (+ 25%) as well as a pronounced amino acid imbalance were observed in obese rats with HFpEF. SDMA levels in O-ZSF1 were comparable to L-ZSF1, indicating stable kidney function. Anatomy and zonula occludens protein density in the intestinal epithelium remained unchanged, but both impedance measurements and increased levels of LPS indicated an impaired epithelial barrier function. FMO3 was decreased (- 20%) in the enlarged, but histologically normal livers of O-ZSF1. Alpha diversity, as indicated by the Shannon diversity index, was comparable at 8 weeks of age, but decreased by 13 weeks of age, when HFpEF manifests in O-ZSF1. Bray-Curtis dissimilarity (Beta-Diversity) was shown to be effective in differentiating L-ZSF1 from O-ZSF1 at 20 weeks of age. Members of the microbial families Lactobacillaceae, Ruminococcaceae, Erysipelotrichaceae and Lachnospiraceae were significantly differentially abundant in O-ZSF1 and L-ZSF1 rats.

CONCLUSIONS

In the ZSF1 HFpEF rat model, increased dietary intake is associated with alterations in gut microbiome composition and bacterial metabolites, an impaired intestinal barrier, and changes in pro-inflammatory and health-predictive metabolic profiles. HFpEF as well as its most common comorbidities obesity and metabolic syndrome and the alterations described here evolve in parallel and are likely to be interrelated and mutually reinforcing. Dietary adaption may have a positive impact on all entities.

Kidney-tonifying blood-activating decoction delays ventricular remodeling in rats with chronic heart failure by regulating gut microbiota and metabolites and p38 mitogen-activated protein kinase/p65 nuclear factor kappa-B/aquaporin-4 signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Myocardial infarction has likely contributed to the increased prevalence of heart failure(HF).As a result of ventricular remodeling and reduced cardiac function, colonic blood flow decreases, causing mucosal ischemia and hypoxia of the villous structure of the intestinal wall.This damage in gut barrier function increases bowel wall permeability, leading to fluid metabolism disorder,gut microbial dysbiosis, increased gut bacteria translocation into the circulatory system and increased circulating endotoxins, thus promoting a typical inflammatory state.Traditional Chinese Medicine plays a key role in the prevention and treatment of HF.Kidney-tonifying Blood-activating(KTBA) decoction has been proved for clinical treatment of chronic HF.However,the mechanism of KTBA decoction on chronic HF is still unclear.

AIMS OF THE STUDY

The effect of KTBA decoction on gut microbiota and metabolites and p38MAPK/p65NF-κB/AQP4 signaling in rat colon was studied to investigate the mechanism that KTBA decoction delays ventricular remodeling and regulates water metabolism disorder in rats with HF after myocardial infarction based on the theory of "Kidney Storing Essence and Conducting Water".

MATERIAL AND METHODS

In vivo,a rat model of HF after myocardial infarction was prepared by ligating the left anterior descending coronary artery combined with exhaustive swimming and starvation.The successful modeling rats were randomly divided into five groups:model group, tolvaptan group(gavaged 1.35mg/(kg•D) tolvaptan),KTBA decoction group(gavaged 15.75g/(kg•D) of KTBA decoction),KTBA decoction combined with SB203580(p38MAPK inhibitor) group(gavaged 15.75g/(kg•D) of KTBA decoction and intraperitoneally injected 1.5mg/(kg•D) of SB203580),and KTBA decoction combined with PDTC(p65NF-kB inhibitor) group(gavaged 15.75g/(kg•D) of KTBA decoction and intraperitoneally injected 120mg/(kg•D) of PDTC).The sham-operation group and model group were gavaged equal volume of normal saline.After 4 weeks of intervention with KTBA decoction,the effect of KTBA decoction on the cardiac structure and function of chronic HF model rats was observed by ultrasonic cardiogram.General state and cardiac index in rats were evaluated.Enzyme linked immunosorbent assay(ELISA) was used to measure N-terminal pro-brain natriuretic peptide (NT-proBNP) concentration in rat serum.Hematoxylin and eosin(H&E) staining,and transmission electron microscope(TEM) were used to observe the morphology and ultrastructure of myocardial and colonic tissue,and myocardial fibrosis was measured by Masson's staining.Cardiac E-cadherin level was detected by Western blot.The mRNA expression and protein expression levels of p38MAPK,I-κBα, p65NF-κB,AQP4,Occludin and ZO-1 in colonic tissue were detected by reverse transcription-quantitative real-time polymerase chain reaction(RT-qPCR) and immunohistochemistry. Protein expression of p38MAPK, p-p38MAPK,I-κBα,p-I-κBα,p65NF-κB, p-p65NF-κB,AQP4,Occludin and ZO-1 in rat colon was detected using Western blot.Colonic microbiota and serum metabolites were respectively analyzed by amplicon sequencing and liquid chromatography-mass spectrometry.In vitro, CCD-841CoN cell was placed in the ischemic solution under hypoxic conditions (94%N2,5%CO2,and 1%O2) in a 37 °C incubator to establish an ischemia and hypoxia model.The CCD-841CoN cells were divided into 7 groups, namely blank group and model group with normal rat serum plus control siRNA, tolvaptan group with rat serum containing tolvaptan plus control siRNA, KTBA group with rat serum containing KTBA plus control siRNA, KTBA plus p38MAPK siRNA group, KTBA plus p65NF-κB siRNA group,and KTBA plus AQP4siRNA group.After 24h and 48h of intervention with KTBA decoction,RT-qPCR,immunofluorescence and Western blot was used to detect the mRNA expression and protein expression levels of p38MAPK,I-κBα,p65NF-κB,AQP4, Occludin and ZO-1 in CCD-841CoN cells.

RESULTS

Compared with the model, KTBA decoction improved the general state, decraesed the serum NT-proBNP level,HW/BW ratio, LVIDd and LVIDs, increased E-cadherin level,EF and FS,reduced number of collagen fibers deposited in the myocardial interstitium,and recovered irregular arrangement of myofibril and swollen or vacuolated mitochondria with broken crista in myocardium.Moreover, KTBA decoction inhibited the expression of p38MAPK,I-κBα,and p65NF-κB and upregulated AQP4, Occludin and ZO-1 in colon tissues and CCD-841CoN cells.Additionally,p38siRNA or SB203580, p65siRNA or PDTC, and AQP4siRNA partially weakened the protective effects of KTBA in vitro and vivo.Notably,The LEfSe analysis results showed that there were six gut biomaker bacteria in model group, including Allobaculum, Bacillales,Turicibacter, Turicibacterales,Turicibacteraceae,and Bacilli. Besides, three gut biomaker bacteria containing Deltaproteobacteria, Desulfovibrionaceae,and Desulfovibrionales were enriched by KTBA treatment in chronic HF model.There were five differential metabolites, including L-Leucine,Pelargonic acid, Capsidiol,beta-Carotene,and L- Erythrulose, which can be regulated back in the same changed metabolic routes by the intervention of KTBA.L-Leucine had the positive correlation with Bacillales, Turicibacterales,Turicibacteraceae,and Turicibacter.L-Leucine significantly impacts Protein digestion and absorption, Mineral absorption,and Central carbon metabolism in cancer regulated by KTBA, which is involved in the expression of MAPK and tight junction in intestinal epithelial cells.

CONCLUSIONS

KTBA decoction manipulates the expression of several key proteins in the p38MAPK/p65NF-κB/AQP4 signaling pathway, modulates gut microbiota and metabolites toward a more favorable profile, improves gut barrier function, delays cardiomyocyte hypertrophy and fibrosis,and improves cardiac function.

Spontaneously hypertensive rats exhibit increased liver flavin monooxygenase expression and elevated plasma TMAO levels compared to normotensive and Ang II-dependent hypertensive rats

Background: Flavin monooxygenases (FMOs) are enzymes responsible for the oxidation of a broad spectrum of exogenous and endogenous amines. There is increasing evidence that trimethylamine (TMA), a compound produced by gut bacteria and also recognized as an industrial pollutant, contributes to cardiovascular diseases. FMOs convert TMA into trimethylamine oxide (TMAO), which is an emerging marker of cardiovascular risk. This study hypothesized that blood pressure phenotypes in rats might be associated with variations in the expression of FMOs. Methods: The expression of FMO1, FMO3, and FMO5 was evaluated in the kidneys, liver, lungs, small intestine, and large intestine of normotensive male Wistar-Kyoto rats (WKY) and two distinct hypertensive rat models: spontaneously hypertensive rats (SHRs) and WKY rats with angiotensin II-induced hypertension (WKY-ANG). Plasma concentrations of TMA and TMAO were measured at baseline and after intravenous administration of TMA using liquid chromatography-mass spectrometry (LC-MS). Results: We found that the expression of FMOs in WKY, SHR, and WKY-ANG rats was in the descending order of FMO3 > FMO1 >> FMO5. The highest expression of FMOs was observed in the liver. Notably, SHRs exhibited a significantly elevated expression of FMO3 in the liver compared to WKY and WKY-ANG rats. Additionally, the plasma TMAO/TMA ratio was significantly higher in SHRs than in WKY rats. Conclusion: SHRs demonstrate enhanced expression of FMO3 and a higher plasma TMAO/TMA ratio. The variability in the expression of FMOs and the metabolism of amines might contribute to the hypertensive phenotype observed in SHRs.

Gut microbiota connects the brain and the heart: potential mechanisms and clinical implications

Nowadays, high morbidity and mortality of cardiovascular diseases (CVDs) and high comorbidity rate of neuropsychiatric disorders contribute to global burden of health and economics. Consequently, a discipline concerning abnormal connections between the brain and the heart and the resulting disease states, known as psychocardiology, has garnered interest among researchers. However, identifying a common pathway that physicians can modulate remains a challenge. Gut microbiota, a constituent part of the human intestinal ecosystem, is likely involved in mutual mechanism CVDs and neuropsychiatric disorder share, which could be a potential target of interventions in psychocardiology. This review aimed to discuss complex interactions from the perspectives of microbial and intestinal dysfunction, behavioral factors, and pathophysiological changes and to present possible approaches to regulating gut microbiota, both of which are future directions in psychocardiology.

Intestinal mucosal barrier: a potential target for traditional Chinese medicine in the treatment of cardiovascular diseases

Cardiovascular disease (CVD) is a serious public health problem, and among non-communicable diseases, CVD is now the leading cause of mortality and morbidity worldwide. CVD involves multiple organs throughout the body, especially the intestinal tract is the first to be involved. The impairment of the intestinal mucosal barrier is considered a significant pathological alteration in CVD and also contributes to the accelerated progression of the disease, thereby offering novel insights for CVD prevention and treatment. The treatment of Chinese medicine is characterized by multi-metabolites, multi-pathways, and multi-targets. In recent years, the studies of Traditional Chinese Medicine (TCM) in treating CVD by repairing the intestinal mucosal barrier have gradually increased, showing great therapeutic potential. This review summarizes the studies related to the treatment of CVD by TCM (metabolites of Chinese botanical drugs, TCM formulas, and Chinese patent medicine) targeting the repair of the intestinal mucosal barrier, as well as the potential mechanisms. We have observed that TCM exerts regulatory effects on the structure and metabolites of gut microbiota, enhances intestinal tight junctions, improves intestinal dyskinesia, repairs intestinal tissue morphology, and preserves the integrity of the intestinal vascular barrier through its anti-inflammatory, antioxidant, and anti-apoptotic properties. These multifaceted attributes position TCM as a pivotal modulator of inhibiting myocardial fibrosis, and hypertrophy, and promoting vascular repairment. Moreover, there exists a close association between cardiovascular risk factors such as hyperlipidemia, obesity, and diabetes mellitus with CVD. We also explore the mechanisms through which Chinese botanical drugs impact the intestinal mucosal barrier and regulate glucose and lipid metabolism. Consequently, these findings present novel insights and methodologies for treating CVD.

Hypertensive rats show increased renal excretion and decreased tissue concentrations of glycine betaine, a protective osmolyte with diuretic properties

Hypertension leads to water-electrolyte disturbances and end-organ damage. Betaine is an osmolyte protecting cells against electrolyte imbalance and osmotic stress, particularly in the kidneys. This study aimed to evaluate tissue levels and hemodynamic and renal effects of betaine in normotensive and hypertensive rats. Betaine levels were assessed using high-performance liquid chromatography-mass spectrometry (HPLC-MS) in normotensive rats (Wistar-Kyoto, WKYs) and Spontaneously Hypertensive rats (SHRs), a model of genetic hypertension. Acute effects of IV betaine on blood pressure, heart rate, and minute diuresis were evaluated. Gene and protein expression of chosen kidney betaine transporters (SLC6a12 and SLC6a20) were assessed using real-time PCR and Western blot. Compared to normotensive rats, SHRs showed significantly lower concentration of betaine in blood serum, the lungs, liver, and renal medulla. These changes were associated with higher urinary excretion of betaine in SHRs (0.20 ± 0.04 vs. 0.09 ± 0.02 mg/ 24h/ 100g b.w., p = 0.036). In acute experiments, betaine increased diuresis without significantly affecting arterial blood pressure. The diuretic response was greater in SHRs than in WKYs. There were no significant differences in renal expression of betaine transporters between WKYs and SHRs. Increased renal excretion of betaine contributes to decreased concentration of the protective osmolyte in tissues of hypertensive rats. These findings pave the way for studies evaluating a causal relation between depleted betaine and hypertensive organ damage, including kidney injury.

Mechanistic Review on the Role of Gut Microbiota in the Pathology of Cardiovascular Diseases

Cardiovascular diseases (CVDs), which stand as the primary contributors to illness and death on a global scale, include vital risk factors like hyperlipidemia, hypertension, diabetes, and smoking, to name a few. However, conventional cardiovascular risk factors offer only partial insight into the complexity of CVDs. Lately, a growing body of research has illuminated that the gut microbiome and its by-products are also of paramount importance in the initiation and progression of CVDs. The gastrointestinal tract houses trillions of microorganisms, commonly known as gut microbiota, that metabolize nutrients, yielding substances like trimethylamine-N-oxide (TMAO), bile acids (BAs), short-chain fatty acids (SCFAs), indoxyl sulfate (IS), and so on. Strategies aimed at addressing these microbes and their correlated biological pathways have shown promise in the management and diagnosis of CVDs. This review offers a comprehensive examination of how the gut microbiota contributes to the pathogenesis of CVDs, particularly atherosclerosis, hypertension, heart failure (HF), and atrial fibrillation (AF), explores potential underlying mechanisms, and highlights emerging therapeutic prospects in this dynamic domain.

LuQi Formula relieves ventricular remodeling through improvement of HIF-1α-mediated intestinal barrier integrity

BACKGROUND

Ventricular remodeling is the adaptive process in which the heart undergoes changes due to stress, leading to heart failure (HF). The progressive decline in cardiac function is considered to contribute to intestinal barrier impairment. LuQi Formula (LQF) is a traditional Chinese medicine preparation widely used in the treatment of ventricular remodeling and HF. However, the role of LQF in the impairment of intestinal barrier function induced by ventricular remodeling remains unclear.

MATERIALS AND METHODS

Ventricular remodeling was induced in rats by permanently ligating the left anterior descending branch coronary artery, and cardiac function indexes were assessed using echocardiography. Heart and colon tissue morphology were observed by hematoxylin-eosin, Masson's trichrome and Alcian Blue Periodic acid Schiff staining. Myocardial cell apoptosis was detected using TUNEL and immunohistochemistry. Circulatory levels of brain natriuretic peptide (BNP), intestinal permeability markers endotoxin, D-lactate and zonulin, as well as inflammatory cytokines tumor necrosis factor alpha and interleukin-1 beta were measured by Enzyme-linked immunosorbent assay. Expression levels of tight junction (TJ) proteins and hypoxia-inducible factor-1 alpha (HIF-1α) in colon tissue were detected by immunofluorescence, immunohistochemistry and western blotting. Cardiac function indexes and intestinal permeability markers of patients with HF were analyzed before and after 2-4 months of LQF treatment.

RESULTS

LQF protected cardiac function and alleviated myocardial fibrosis and apoptosis in rats with ventricular remodeling. LQF protected the intestinal barrier integrity in ventricular remodeling rats, including maintaining colonic tissue morphology, preserving the number of goblet cells and normal expression of TJ proteins. Furthermore, LQF upregulated the expression of HIF-1α protein in colon tissue. Intervention with a HIF-1α inhibitor weakened the protective effect of LQF on intestinal barrier integrity. Moreover, a reduction of HIF-1α aggravated ventricular remodeling, which could be alleviated by LQF. Correspondingly, the circulating levels of intestinal permeability markers and BNP in HF patients were significantly decreased, and cardiac function markedly improved following LQF treatment.

CONCLUSIONS

We demonstrated that LQF effectively protected cardiac function by preserving intestinal barrier integrity caused by ventricular remodeling, at least partially through upregulating HIF-1α expression.

The Association of Circulating L-Carnitine, γ-Butyrobetaine and Trimethylamine N-Oxide Levels with Gastric Cancer

Our study aimed to evaluate the association between gastric cancer (GC) and higher concentrations of the metabolites L-carnitine, γ-butyrobetaine (GBB) and gut microbiota-mediated trimethylamine N-oxide (TMAO) in the circulation. There is evidence suggesting that higher levels of TMAO and its precursors in blood can be indicative of either a higher risk of malignancy or indeed its presence; however, GC has not been studied in this regard until now. Our study included 83 controls without high-risk stomach lesions and 105 GC cases. Blood serum L-carnitine, GBB and TMAO levels were measured by ultra-high-performance liquid chromatography–mass spectrometry (UPLC/MS/MS). Although there were no significant differences between female control and GC groups, we found a significant difference in circulating levels of metabolites between the male control group and the male GC group, with median levels of L-carnitine reaching 30.22 (25.78–37.57) nmol/mL vs. 37.38 (32.73–42.61) nmol/mL (p < 0.001), GBB–0.79 (0.73–0.97) nmol/mL vs. 0.97 (0.78–1.16) nmol/mL (p < 0.05) and TMAO–2.49 (2.00–2.97) nmol/mL vs. 3.12 (2.08–5.83) nmol/mL (p < 0.05). Thus, our study demonstrated the association between higher blood levels of L-carnitine, GBB, TMAO and GC in males, but not in females. Furthermore, correlations of any two investigated metabolites were stronger in the GC groups of both genders in comparison to the control groups. Our findings reveal the potential role of L-carnitine, GBB and TMAO in GC and suggest metabolic differences between genders. In addition, the logistic regression analysis revealed that the only significant factor in terms of predicting whether the patient belonged to the control or to the GC group was the blood level of L-carnitine in males only. Hence, carnitine might be important as a biomarker or a risk factor for GC, especially in males.

Phenylacetylglutamine increases the susceptibility of ventricular arrhythmias in heart failure mice by exacerbated activation of the TLR4/AKT/mTOR signaling pathway

BACKGROUND

Intestinal microbial metabolites are a risk factor for cardiovascular diseases, and phenylacetylglutamine (PAGln) is a newly discovered intestinal metabolite in the latest study. In addition, elevated plasma PAGln concentration was associated with increased mortality and hospitalization rates in patients with heart failure (HF). However, the mechanism of PAGln leading to increased HF mortality is unclear. The present study was performed to investigate whether the PAGln deteriorated the susceptibility of ventricular arrhythmias (VAs) in the setting of HF.

METHODS

Thoracic aortic coarctation (TAC) was used to construct an animal model of HF in mice. Intraperitoneal injection of PAGln for 4 weeks intervened in HF mice. The concentration of PAGln was quantitatively determined by liquid chromatography-tandem mass spectrometry. Cardiac function was assessed by echocardiography; assessment of cardiac electrophysiological indexes was measured by electrocardiogram (ECG) and programmed electrical stimulation in isolated cardiac perfusion. Masson was stained for collagen deposition, and wheat germ agglutinin (WGA) was stained for the cross-sectional area of the myocytes. The qRT-PCR and Western Blotting were used to determine target gene expression in vivo and in vitro.

RESULTS

PAGln promoted the activation of cardiac inflammation and fibrosis and deteriorated cardiac function in HF mice. Moreover, PAGln extended APD90, shortened the ERP/APD90 and increased the incidence of VAs following HF in isolated heart perfusion. Mechanistically, PAGln significantly enhanced the activation of the TLR4/AKT/mTOR signaling pathway in vivo and in vitro.

CONCLUSIONS

PAGln increased the susceptibility of VAs in HF mice by activating the TLR4/AKT/mTOR signaling pathway.

Gut Molecules in Cardiometabolic Diseases: The Mechanisms behind the Story

Atherosclerotic cardiovascular disease is the most common cause of morbidity and mortality worldwide. Diabetes mellitus increases cardiovascular risk. Heart failure and atrial fibrillation are associated comorbidities that share the main cardiovascular risk factors. The use of incretin-based therapies promoted the idea that activation of alternative signaling pathways is effective in reducing the risk of atherosclerosis and heart failure. Gut-derived molecules, gut hormones, and gut microbiota metabolites showed both positive and detrimental effects in cardiometabolic disorders. Although inflammation plays a key role in cardiometabolic disorders, additional intracellular signaling pathways are involved and could explain the observed effects. Revealing the involved molecular mechanisms could provide novel therapeutic strategies and a better understanding of the relationship between the gut, metabolic syndrome, and cardiovascular diseases.

Dityrosine in food: A review of its occurrence, health effects, detection methods, and mitigation strategies

Protein and amino acid oxidation in food products produce many new compounds, of which the reactive and toxic compound dityrosine, derived from oxidized tyrosine, is the most widely studied. The high reactivity of dityrosine enables this compound to induce oxidative stress and disrupt thyroid hormone function, contributing to the pathological processes of several diseases, such as obesity, diabetes, cognitive dysfunction, aging, and age-related diseases. From the perspective of food safety and human health, protein-oxidation products in food are the main concern of consumers, health management departments, and the food industry. This review highlights the latest research on the formation pathways, toxicity, detection methods, occurrence in food, and mitigation strategies for dityrosine. Furthermore, the control of dityrosine in family cooking and food-processing industry has been discussed. Food-derived dityrosine primarily originates from high-protein foods, such as meat and dairy products. Considering its toxicity, combining rapid high sensitivity dityrosine detection techniques with feasible control methods could be an effective strategy to ensure food safety and maintain human health. However, the current dityrosine detection and mitigation strategies exhibit some inherent characteristics and limitations. Therefore, developing technologies for rapid and effective dityrosine detection and control at the industrial level is necessary.

Inhibiting Intestinal Krüppel-Like Factor 5 Impairs the Beneficial Role of Renal Denervation in Gut Microbiota in Rats with Heart Failure

Krüppel-like factor 5 (KLF5) is critical in maintaining intestinal barrier function, and renal denervation (RDN) mitigates gut microbiota aberrations in rats with heart failure (HF). It is unclear whether intestinal KLF5 can be regulated by RDN and whether inhibiting intestinal KLF5 weakens the beneficial role of RDN on gut microbiota. Sprague-Dawley rats were distributed into a CG (sham transverse aortic constriction [TAC] and sham RDN), HF (induced by TAC), or RDN (underwent RDN after TAC) group or a CG.M, HF.M, or RDN.M group, which included the administration of the KLF5 inhibitor to the CG, HF, or RDN group, respectively. Transmission electron microscopy, mRNA, and protein expression of KLF5 and desmoglein 2 (DSG2) in jejunum and sequencing of the 16S rRNA gene in fecal samples were evaluated. KLF5 expression was lower in the RDN group than in the HF group (P < 0.001). The microvillus length, density, length-to-width ratio, and DSG2 expression were lower in the RDN.M group than in the RDN group, and the same trend was observed between the HF.M and HF groups (all P < 0.05). The gut bacterial community structure was altered after administration of a KLF5 inhibitor. The abundances of Proteobacteria, Gammaproteobacteria, Sutterella, and Prevotellaceae were higher, and the abundance of Firmicutes was lower in the RDN.M group than in the RDN group (all P < 0.05). These findings indicated that RDN suppressed intestinal KLF5 expression, and inhibiting intestinal KLF5 expression exacerbated the gut microbiota by impairing the intestinal barrier function in HF rats following RDN, which weakened the beneficial role of RDN on gut microbiota. IMPORTANCE Krüppel-like factor 5 (KLF5) is critical for the maintenance of intestinal barrier function. It is unclear whether intestinal KLF5 expression can be affected by renal denervation (RDN) in heart failure (HF) and whether inhibiting intestinal KLF5 expression exacerbates the gut microbiome and weakens the role of RDN in mitigating gut microbiome aberrations in HF rats after RDN. We demonstrated that RDN significantly suppressed intestinal KLF5 expression and that inhibiting intestinal expression of KLF5 exacerbated the gut microbiota and weakened the role of RDN in mitigating microbiota aberrations by impairing intestinal barrier function, resulting in an increase in bacteria harmful to cardiac function and a decrease in beneficial bacteria in HF rats following RDN. This study highlighted the important roles of intestinal KLF5 in modulating gut microbiota in HF and suggested that the influence of RDN on intestinal KLF5 was another possible role of RDN in HF besides downregulating the sympathetic nerve.

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.

The Gut Microbial-Derived Metabolite Trimethylamine N-Oxide and Atrial Fibrillation: Relationships, Mechanisms, and Therapeutic Strategies

Accumulating evidence has demonstrated that gut microbial-derived metabolite trimethylamine N-oxide (TMAO) plays a crucial role in the pathogenesis of many diseases and can be served as a prognostic biomarker for several cardiovascular disorders, including arrhythmia. Recently, some studies have documented that TMAO was associated with the occurrence, progression, recurrence, and embolism risk of atrial fibrillation (AF). The activation of related inflammatory signal pathways and the cardiac sympathetic nervous system (CSNS) caused by elevated TAMO may be the underlying mechanism. It is worth noting that intervention in the metabolic pathway of TMAO may be an underlying therapeutic target of AF. In addition, standardized and individualized treatment strategies in clinical practice may be of great significance for AF patients, particularly those with high serum TMAO concentrations. However, there are also contradictions in the current research on TMAO and AF. Moreover, notwithstanding the positive preclinical and clinical findings, data supporting a direct association between TMAO and AF is a paucity. Thus, conclusive evidence from preclinical studies and multi-center randomized controlled trials to reveal the essential relationship between TMAO and AF is needy. In this review, we have attempted to summarize recent studies on TMAO and AF, highlighted the potential therapeutic strategies for AF patients, followed by a discussion on directions for future research in this field.

Interplay Between Gut Microbiota and Amino Acid Metabolism in Heart Failure

Heart failure (HF) is a complex clinical syndrome of which the incidence is on the rise worldwide. Cardiometabolic disorders are associated with the deterioration of cardiac function and progression of HF. Recently, there has been renewed interest in gut microbiota (GM) and its metabolites in the cardiovascular disease. HF-caused hypoperfusion could increase intestinal permeability, and a “leaky” bowel leads to bacterial translocation and make its metabolites more easily enter the circulation. Considerable evidence shows that the composition of microbiota and amino acids (AAs) has been altered in HF patients, and AAs could serve as a diagnostic and prognostic biomarker in HF. The findings indicate that the gut–amino acid–HF axis may play a key role in the progression of HF. In this paper, we focus on the interrelationship between the AA metabolism and GM alterations during the development of heart failure. We also discuss the potential prognostic and therapeutic value of the gut–amino acid–HF axis in the cortex of HF.

The Protective Role of the Long Pentraxin PTX3 in Spontaneously Hypertensive Rats with Heart Failure

Pentraxin 3 (PTX3) is synthesized locally and released into the circulation, reflecting local inflammation in the cardiovascular system. Therefore, we conducted a study to explore the effect of PTX3 in spontaneously hypertensive heart failure (SHHF) rats. Sprague Dawley (SD) and SHHF rats were treated with recombinant PTX3 protein, and the blood pressure (BP) and echocardiographic parameters were collected. Radioimmunoassay, enzyme immunoassay and enzyme-linked immunosorbent assay (ELISA) were applied to detect plasma levels of atrial/B-type natriuretic peptide (ANP/BNP) and PTX3. The pathological changes in the myocardial tissues were observed by hematoxylin and eosin (HE) and Masson stainings. The mRNA and protein expressions were detected by quantitative real-time reverse-transcription polymerase chain reaction (qPCR) and western blotting. Cardiomyocyte apoptosis was evaluated by TUNEL staining and DNA fragmentation test. Increased plasma concentrations of PTX3 were found in SHHF rats compared with SD rats, which was further enhanced by recombinant PTX3 protein. After injection with recombinant PTX3 protein, the heart function was improved in SHHF rats with the decreased systolic and diastolic BP, and the reduced plasma levels of ANP and BNP. Moreover, PTX3 improved the myocardial damage and interstitial fibrosis in SHHF rats with reduced cardiomyocyte apoptosis and decreased mRNA expressions of pro-inflammatory factors in myocardial tissues. PTX3 could decrease the BP and plasma levels of ANP and BNP in SHHF rats, as well as improve the inflammation, cardiomyocyte apoptosis, and pathological changes of myocardial tissues, suggesting it may be a useful intervention in the treatment of SHHF.

Emerging role of trimethylamine-N-oxide (TMAO) in colorectal cancer

Among gut microbiota-derived metabolites, trimethylamine-N-oxide (TMAO) is receiving increased attention due to its possible role in the carcinogenesis of colorectal cancer (CRC). In spite of numerous reports implicating TMAO with CRC, there is a lack of empirical mechanistic evidences to concretize the involvement of TMAO in the carcinogenesis of CRC. Possible mechanisms such as inflammation, oxidative stress, DNA damage, and protein misfolding by TMAO have been discussed in this review in the light of the latest advancements in the field. This review is an attempt to discuss the probable correlation between TMAO and CRC but this linkage can be concretized only once we get sufficient empirical evidences from the mechanistic studies. We believe, this review will augment the understanding of linking TMAO with CRC and will motivate researchers to move towards mechanistic study for reinforcing the idea of implicating TMAO with CRC causation. KEY POINTS: • TMAO is a gut bacterial metabolite which has been implicated in CRC in recent years. • The valid mechanistic approach of CRC causation by TMAO is unknown. • The article summarizes the possible mechanisms which need to be explored for validation.

Intestinal Barrier Dysfunction Exacerbates Neuroinflammation via the TLR4 Pathway in Mice With Heart Failure

Aims

The present study aimed to investigate alterations in neuroinflammation after heart failure (HF) and explore the potential mechanisms.

Methods

Male wild-type (WT) and Toll-like receptor 4 (TLR4)-knockout (KO) mice were subjected to sham operation or ligation of the left anterior descending coronary artery to induce HF. 8 weeks later, cardiac functions were analyzed by echocardiography, and intestinal barrier functions were examined by measuring tight junction protein expression, intestinal permeability and plasma metabolite levels. Alterations in neuroinflammation in the brain were examined by measuring microglial activation, inflammatory cytokine levels and the proinflammatory signaling pathway. The intestinal barrier protector intestinal alkaline phosphatase (IAP) and intestinal homeostasis inhibitor L-phenylalanine (L-Phe) were used to examine the relationship between intestinal barrier dysfunction and neuroinflammation in mice with HF.

Results

Eight weeks later, WT mice with HF displayed obvious increases in intestinal permeability and plasma lipopolysaccharide (LPS) levels, which were accompanied by elevated expression of TLR4 in the brain and enhanced neuroinflammation. Treatment with the intestinal barrier protector IAP significantly attenuated neuroinflammation after HF while effectively increasing plasma LPS levels. TLR4-KO mice showed significant improvements in HF-induced neuroinflammation, which was not markedly affected by intestinal barrier inhibitors or protectors.

Conclusion

HF could induce intestinal barrier dysfunction and increase gut-to-blood translocation of LPS, which could further promote neuroinflammation through the TLR4 pathway.

The impact of gut microbiota metabolites on cellular bioenergetics and cardiometabolic health

Recent research demonstrates a reciprocal relationship between gut microbiota-derived metabolites and the host in controlling the energy homeostasis in mammals. On the one hand, to thrive, gut bacteria exploit nutrients digested by the host. On the other hand, the host utilizes numerous products of gut bacteria metabolism as a substrate for ATP production in the colon. Finally, bacterial metabolites seep from the gut into the bloodstream and interfere with the host’s cellular bioenergetics machinery. Notably, there is an association between alterations in microbiota composition and the development of metabolic diseases and their cardiovascular complications. Some metabolites, like short-chain fatty acids and trimethylamine, are considered markers of cardiometabolic health. Others, like hydrogen sulfide and nitrite, demonstrate antihypertensive properties. Scientific databases were searched for pre-clinical and clinical studies to summarize current knowledge on the role of gut microbiota metabolites in the regulation of mammalian bioenergetics and discuss their potential involvement in the development of cardiometabolic disorders. Overall, the available data demonstrates that gut bacteria products affect physiological and pathological processes controlling energy and vascular homeostasis. Thus, the modulation of microbiota-derived metabolites may represent a new approach for treating obesity, hypertension and type 2 diabetes.

Assessment of trimethylamine N-oxide (TMAO) as a potential biomarker of severe stress in patients vulnerable to posttraumatic stress disorder (PTSD) after acute myocardial infarction

Background: Posttraumatic stress disorder (PTSD) is a frequently observed stress-related disorder after acute myocardial infarction (AMI) and it is characterized by numerous symptoms, such as flashbacks, intrusions and anxiety, as well as uncontrollable thoughts and feelings related to the trauma. Biological correlates of severe stress might contribute to identifying PTSD-vulnerable patients at an early stage. Objective: Aims of the study were (1) to determine whether blood levels of trimethylamine N-oxide (TMAO) vary immediately after AMI in patients with/without AMI-induced PTSD symptomatology, (2) to investigate whether TMAO is a potential biomarker that might be useful in the prediction of PTSD and the PTSD symptom subclusters re-experiencing, avoidance and hyperarousal, and (3) to investigate whether TMAO varies immediately after AMI in patients with/without depression 6 months after AMI. Method: A total of 114 AMI patients were assessed with the Hamilton-Depression Scale after admission to the hospital and 6 months later. The Clinician Administered PTSD Scale for DSM-5 was used to explore PTSD-symptoms at the time of AMI and 6 months after AMI. To assess patients' TMAO status, serum samples were collected at hospitalization and 6 months after AMI. Results: Participants with PTSD-symptomatology had significantly higher TMAO levels immediately after AMI than patients without PTSD-symptoms (ANCOVA: TMAO(PTSD x time), F = 4.544, df = 1, p = 0.035). With the inclusion of additional clinical predictors in a hierarchical logistic regression model, TMAO became a significant predictor of PTSD-symptomatology. No significant differences in TMAO levels immediately after AMI were detected between individuals with/without depression 6 months after AMI. Conclusions: An elevated TMAO level immediately after AMI might reflect severe stress in PTSD-vulnerable patients, which might also lead to a short-term increase in gut permeability to trimethylamine, the precursor of TMAO. Thus, an elevated TMAO level might be a biological correlate for severe stress that is associated with vulnerability to PTSD.