Gut microbiota production of trimethyl-5-aminovaleric acid reduces fatty acid oxidation and accelerates cardiac hypertrophy

Microbiota-derived acetylcholine can promote gut motility in Drosophila melanogaster

The gut microbiota is crucial for intestinal health, including gastrointestinal (GI) motility. How commensal bacterial species influence GI motility has not been fully elucidated. A major factor of GI motility is the gut contraction promoting the propulsive movement of orally ingested materials. Here, we developed a method to monitor and quantify gut contractions in living Drosophila melanogaster larvae. We found that the culture medium of an isolated strain Lactiplantibacillus plantarum Lsi promoted gut contraction in vivo, which was not observed in Leuconostoc sp. Leui nor Acetobacter persici Ai culture medium. To identify bacteria-derived metabolites, we performed metabolome analysis of the culture media by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Of the 66 metabolites detected, we found that some metabolites changed in a species-specific manner. Among them, acetylcholine was specifically produced by L. plantarum. Feeding exogenous acetylcholine increased the frequency of gut contractions, which was blocked by D-tubocurarine, an inhibitor of nicotinic acetylcholine receptors. In this study, we propose a mechanism by which the gut microbiota influences Drosophila gut motility. This article is part of the theme issue 'Sculpting the microbiome: how host factors determine and respond to microbial colonization'.

Lipotoxicity as a therapeutic target in obesity and diabetic cardiomyopathy

Unhealthy sources of fats, ultra-processed foods with added sugars, and a sedentary lifestyle make humans more susceptible to developing overweight and obesity. While lipids constitute an integral component of the organism, excessive and abnormal lipid accumulation that exceeds the storage capacity of lipid droplets disrupts the intracellular composition of fatty acids and results in the release of deleterious lipid species, thereby giving rise to a pathological state termed lipotoxicity. This condition induces endoplasmic reticulum stress, mitochondrial dysfunction, inflammatory responses, and cell death. Recent advances in omics technologies and analytical methodologies and clinical research have provided novel insights into the mechanisms of lipotoxicity, including gut dysbiosis, epigenetic and epitranscriptomic modifications, dysfunction of lipid droplets, post-translational modifications, and altered membrane lipid composition. In this review, we discuss the recent knowledge on the mechanisms underlying the development of lipotoxicity and lipotoxic cardiometabolic disease in obesity, with a particular focus on lipotoxic and diabetic cardiomyopathy.

Metabolomic profiles during early childhood and risk of food allergies and asthma in multiethnic children from a prospective birth cohort

BACKGROUND

There are increasing numbers of metabolomic studies in food allergy (FA) and asthma, which, however, are predominantly limited by cross-sectional designs, small sample size, and being conducted in European populations.

OBJECTIVE

We sought to identify metabolites unique to and shared by children with FA and/or asthma in a racially diverse prospective birth cohort, the Boston Birth Cohort.

METHODS

Mass spectrometry-based untargeted metabolomic profiling was performed using venous plasma collected in early childhood (n = 811). FA was diagnosed according to clinical symptoms consistent with an acute hypersensitivity reaction at food ingestion and food specific-IgE > 0.35 kU/L. Asthma was defined on the basis of physician diagnosis. Generalized estimating equations were applied to analyze metabolomic associations with FA and asthma, adjusting for potential confounders.

RESULTS

During a mean ± standard deviation follow-up of 11.8 ± 5.2 years from birth, 78 children developed FA and 171 developed asthma. Androgenic and pregnenolone steroids were significantly associated with a lower risk of FA, especially for egg allergy. N,N,N-trimethyl-5-aminovalerate (odds ratio [OR] = 0.65, 95% confidence interval [CI] = 0.48-0.87), and 1-oleoyl-2-arachidonoyl-sn-glycero-3-phosphoinositol (OR = 0.77; 95% CI = 0.66-0.90) were inversely associated with FA risk. Orotidine (OR = 4.73; 95% CI = 2.2-10.2) and 4-cholesten-3-one (OR = 0.52; 95% CI = 0.35-0.77) were the top 2 metabolites associated with risk of asthma, although they had no association with FA. In comparison, children with both FA and asthma exhibited an altered metabolomic profile that aligned with that of FA, including altered levels of lipids and steroids.

CONCLUSION

In this US multiethnic prospective birth cohort, unique and shared alterations in plasma metabolites during early childhood were associated with risk of developing FA and/or asthma. These findings await further validation.

Cardiac energy metabolism disorder mediated by energy substrate imbalance and mitochondrial damage upon tebuconazole exposure

Tebuconazole exposure has been described as an increasing hazard to human health. An increasing number of recent studies have shown a positive association between tebuconazole exposure and cardiovascular disease risk, which is characterized by the reduction of adenosine triphosphate (ATP) synthesis. However, researches on the damage of tebuconazole exposure to energy metabolism and the related molecular mechanisms are limited. In the present study, male C57BL/6 mice were treated with tebuconazole at different low concentrations for 4 weeks. The results indicated that tebuconazole could accumulate in the heart and further induce the decrease of ATP content in the mouse heart. Importantly, tebuconazole induced an obvious shift in substrate utilization of fatty acid and glucose by disrupting their corresponding transporters (GLUT1, GLUT4, CD36, FABP3 and FATP1) expression, and significantly repressed the expression of mitochondrial biogenesis (Gabpa and Tfam) and oxidative phosphorylation (CS, Ndufa4, Sdhb, Cox5a and Atp5b) related genes in a dose-dependent manner. Further investigation revealed that these alterations were related to the IRS1/AKT and PPARγ/RXRα pathways. These findings contribute to a better understanding of triazole fungicide-induced cardiovascular disease by revealing the key indicators associated with this phenomenon.

Role of the intestinal microbiome and its therapeutic intervention in cardiovascular disorder

The gut microbiome is a heterogeneous population of microbes comprising viruses, bacteria, fungi, and protozoa. Such a microbiome is essential for sustaining host equilibrium, and its impact on human health can be altered by a variety of factors such as external variables, social behavior, age, nutrition, and genetics. Gut microbes' imbalances are related to a variety of chronic diseases including cancer, obesity, and digestive disorders. Globally, recent findings show that intestinal microbes have a significant role in the formation of cardiovascular disease (CVD), which is still the primary cause of fatalities. Atherosclerosis, hypertension, diabetes, inflammation, and some inherited variables are all cardiovascular risk variables. However, studies found correlations between metabolism, intestinal flora, and dietary intake. Variations in the diversity of gut microbes and changes in their activity are thought to influence CVD etiology. Furthermore, the gut microbiota acts as an endocrine organ, producing bioactive metabolites such as TMA (trimethylamine)/TMAO (trimethylamine N-oxide), SCFA (short-chain fatty acids), and bile acids, which have a substantial impact on host wellness and disease by multiple mechanisms. The purpose of this overview is to compile current evidence highlighting the intricate links between gut microbiota, metabolites, and the development of CVD. It focuses on how intestinal dysbiosis promotes CVD risk factors such as heart failure, hypertension, and atherosclerosis. This review explores the normal physiology of intestinal microbes and potential techniques for targeting gut bacteria for CVD treatment using various microbial metabolites. It also examines the significance of gut bacteria in disease treatment, including supplements, prebiotics, probiotics, antibiotic therapies, and fecal transplantation, which is an innovative approach to the management of CVD. As a result, gut bacteria and metabolic pathways become increasingly attractive as potential targets for CVD intervention.

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.

Blood-Derived Lipid and Metabolite Biomarkers in Cardiovascular Research from Clinical Studies: A Recent Update

The primary prevention, early detection, and treatment of cardiovascular disease (CVD) have been long-standing scientific research goals worldwide. In the past decades, traditional blood lipid profiles have been routinely used in clinical practice to estimate the risk of CVDs such as atherosclerotic cardiovascular disease (ASCVD) and as treatment targets for the primary prevention of adverse cardiac events. These blood lipid panel tests often fail to fully predict all CVD risks and thus need to be improved. A comprehensive analysis of molecular species of lipids and metabolites (defined as lipidomics and metabolomics, respectively) can provide molecular insights into the pathophysiology of the disease and could serve as diagnostic and prognostic indicators of disease. Mass spectrometry (MS) and nuclear magnetic resonance (NMR)-based lipidomics and metabolomics analysis have been increasingly used to study the metabolic changes that occur during CVD pathogenesis. In this review, we provide an overview of various MS-based platforms and approaches that are commonly used in lipidomics and metabolomics workflows. This review summarizes the lipids and metabolites in human plasma/serum that have recently (from 2018 to December 2022) been identified as promising CVD biomarkers. In addition, this review describes the potential pathophysiological mechanisms associated with candidate CVD biomarkers. Future studies focused on these potential biomarkers and pathways will provide mechanistic clues of CVD pathogenesis and thus help with the risk assessment, diagnosis, and treatment of CVD.

Danger-associated metabolites trigger metaflammation: A crowbar in cardiometabolic diseases

Cardiometabolic diseases (CMDs) are characterized by a series of metabolic disorders and chronic low-grade inflammation. CMDs contribute to a high burden of mortality and morbidity worldwide. Host-microbial metabolic regulation that triggers metaflammation is an emerging field of study that promotes a new perspective for perceiving cardiovascular risks. The term metaflammation denotes the entire cascade of immune responses activated by a new class of metabolites known as "danger-associated metabolites" (DAMs). It is being proposed by the present review for the first time. We summarize current studies covering bench to bedside aspects of DAMs to better understand CMDs in the context of DAMs. We have focused on the involvement of DAMs in the pathophysiological development of CMDs, including the disruption of immune homeostasis and chronic inflammation-triggered damage leading to CMD-related adverse events, as well as emerging therapeutic approaches for targeting DAM metabolism in CMDs.

Fgf21-Dubosiella axis mediates the protective effects of exercise against NAFLD development

AIM

To explore the mechanism of gut microbiota mediates protective effects of exercise against non-alcoholic fatty liver disease (NAFLD) development.

MAIN METHODS

The male C57BL/6 mice were fed with high fat food (HFD) or normal diet (CON) respectively, and the obese mice were randomly divided into sedentariness (HFD) and exercise groups (HFD + Exe). The total intervention period was 18 weeks. Antibiotic treatment and fecal microbiota transplantation were applied to evaluate gut microbiota mediates the protective effects of exercise against NAFLD development. 16S rDNA profiling of gut microbiota and extracorporeal rehydration of Dubosiella newyorkensis were performed to identify the crucial role of Dubosiella in NAFLD improvement during exercise training. FGF21 knock-out mice were used to reveal the potential mechanism of exercise increased the abundance of Dubosiella. RT-PCR, Western blot, Histopathological examinations and Biochemical testing were performed to evaluate the lipid deposition and function in the liver.

KEY FINDINGS

Treadmill exercise significantly ameliorated hepatic function and mitigated lipid accumulation in NAFLD mice, and these hepatoprotective benefits were mostly mediated by the Dubosiella. In addition, the increased abundance of Dubosiella during exercise training was modulated by FGF21 specifically.

SIGNIFICANCE

In short, Dubosiella, chiefly regulated by FGF21 signaling during exercise training, has been discovered to govern the protective impacts of exercising counter to the development of NAFLD and exhibits a promising treatment target for NAFLD.

Targeting gut microbiota in aging-related cardiovascular dysfunction: focus on the mechanisms

The global population is aging and age-related cardiovascular disease is increasing. Even after controlling for cardiovascular risk factors, readmission and mortality rates remain high. In recent years, more and more in-depth studies have found that the composition of the gut microbiota and its metabolites, such as trimethylamine N-oxide (TMAO), bile acids (BAs), and short-chain fatty acids (SCFAs), affect the occurrence and development of age-related cardiovascular diseases through a variety of molecular pathways, providing a new target for therapy. In this review, we discuss the relationship between the gut microbiota and age-related cardiovascular diseases, and propose that the gut microbiota could be a new therapeutic target for preventing and treating cardiovascular diseases.

Metabolic dynamics and prediction of sFGR and adverse fetal outcomes: a prospective longitudinal cohort study

BACKGROUND

Selective fetal growth restriction (sFGR) is an extreme complication that significantly increases the risk of perinatal mortality and long-term adverse neurological outcomes in offspring, affecting approximately 15% of monochorionic diamniotic (MCDA) twin pregnancies. The lack of longitudinal cohort studies hinders the early prediction and intervention of sFGR.

METHODS

We constructed a prospective longitudinal cohort study of sFGR, and quantified 25 key metabolites in 337 samples from maternal plasma in the first, second, and third trimester and from cord plasma. In particular, our study examined fetal growth and brain injury data from ultrasonography and used the Ages and Stages Questionnaire-third edition subscale (ASQ-3) to evaluate the long-term neurocognitive behavioral development of infants aged 2-3 years. Furthermore, we correlated metabolite levels with ultrasound data, including physical development and brain injury indicators, and ASQ-3 data using Spearman's-based correlation tests. In addition, special combinations of differential metabolites were used to construct predictive models for the occurrence of sFGR and fetal brain injury.

RESULTS

Our findings revealed various dynamic patterns for these metabolites during pregnancy and a maximum of differential metabolites between sFGR and MCDA in the second trimester (n = 8). The combination of L-phenylalanine, L-leucine, and L-isoleucine in the second trimester, which were closely related to fetal growth indicators, was highly predictive of sFGR occurrence (area under the curve [AUC]: 0.878). The combination of L-serine, L-histidine, and L-arginine in the first trimester and creatinine in the second trimester was correlated with long-term neurocognitive behavioral development and showed the capacity to identify fetal brain injury with high accuracy (AUC: 0.94).

CONCLUSIONS

The performance of maternal plasma metabolites from the first and second trimester is superior to those from the third trimester and cord plasma in discerning sFGR and fetal brain injury. These metabolites may serve as useful biomarkers for early prediction and promising targets for early intervention in clinical settings.

Microbe-derived uremic solutes enhance thrombosis potential in the host

p-Cresol sulfate (pCS) and indoxyl sulfate (IS), gut microbiome-derived metabolites, are traditionally associated with cardiovascular disease (CVD) risks in the setting of impaired kidney function. While pharmacologic provision of pCS or IS can promote pro-thrombotic phenotypes, neither the microbial enzymes involved nor direct gut microbial production have been linked to CVD. Untargeted metabolomics was performed on a discovery cohort (n = 1,149) with relatively preserved kidney function, followed by stable isotope-dilution mass spectrometry quantification of pCS and IS in an independent validation cohort (n = 3,954). Genetic engineering of human commensals to produce p-cresol and indole gain-of-function and loss-of-function mutants, followed by colonization of germ-free mice, and studies on host thrombosis were performed. Systemic pCS and IS levels were independently associated with all-cause mortality. Both in vitro and within colonized germ-free mice p-cresol productions were recapitulated by collaboration of two organisms: a Bacteroides strain that converts tyrosine to 4-hydroxyphenylacetate, and a Clostridium strain that decarboxylates 4-hydroxyphenylacetate to p-cresol. We then engineered a single organism, Bacteroides thetaiotaomicron, to produce p-cresol, indole, or both metabolites. Colonizing germ-free mice with engineered strains, we show the gut microbial genes for p-cresol (hpdBCA) and indole (tryptophanase) are sufficient to confer a pro-thrombotic phenotype in vivo. Moreover, human fecal metagenomics analyses show that abundances of hpdBCA and tryptophanase are associated with CVD. These studies show that pCS and IS, two abundant microbiome-derived metabolites, play a broader potential role in CVD than was previously known. They also suggest that therapeutic targeting of gut microbial p-cresol- and indole-producing pathways represent rational targets for CVD.IMPORTANCEAlterations in gut microbial composition and function have been linked to numerous diseases. Identifying microbial pathways responsible for producing molecules that adversely impact the host is an important first step in the development of therapeutic interventions. Here, we first use large-scale clinical observations to link blood levels of defined microbial products to cardiovascular disease risks. Notably, the previously identified uremic toxins p-cresol sulfate and indoxyl sulfate were shown to predict 5-year mortality risks. After identifying the microbes and microbial enzymes involved in the generation of these uremic toxins, we used bioengineering technologies coupled with colonization of germ-free mice to show that the gut microbial genes that generate p-cresol and indole are sufficient to confer p-cresol sulfate and indoxyl sulfate formation, and a pro-thrombotic phenotype in vivo. The findings and tools developed serve as a critical step in both the study and targeting of these gut microbial pathways in vivo.

The potential mechanism of gut microbiota-microbial metabolites-mitochondrial axis in progression of diabetic kidney disease

Diabetic kidney disease (DKD), has become the main cause of end-stage renal disease (ESRD) worldwide. Lately, it has been shown that the onset and advancement of DKD are linked to imbalances of gut microbiota and the abnormal generation of microbial metabolites. Similarly, a body of recent evidence revealed that biological alterations of mitochondria ranging from mitochondrial dysfunction and morphology can also exert significant effects on the occurrence of DKD. Based on the prevailing theory of endosymbiosis, it is believed that human mitochondria originated from microorganisms and share comparable biological characteristics with the microbiota found in the gut. Recent research has shown a strong correlation between the gut microbiome and mitochondrial function in the occurrence and development of metabolic disorders. The gut microbiome's metabolites may play a vital role in this communication. However, the relationship between the gut microbiome and mitochondrial function in the development of DKD is not yet fully understood, and the role of microbial metabolites is still unclear. Recent studies are highlighted in this review to examine the possible mechanism of the gut microbiota-microbial metabolites-mitochondrial axis in the progression of DKD and the new therapeutic approaches for preventing or reducing DKD based on this biological axis in the future.

Dysbiotic Gut Microbiota-Derived Metabolites and Their Role in Non-Communicable Diseases

Dysbiosis, generally defined as the disruption to gut microbiota composition or function, is observed in most diseases, including allergies, cancer, metabolic diseases, neurological disorders and diseases associated with autoimmunity. Dysbiosis is commonly associated with reduced levels of beneficial gut microbiota-derived metabolites such as short-chain fatty acids (SCFA) and indoles. Supplementation with these beneficial metabolites, or interventions to increase their microbial production, has been shown to ameliorate a variety of inflammatory diseases. Conversely, the production of gut 'dysbiotic' metabolites or by-products by the gut microbiota may contribute to disease development. This review summarizes the various 'dysbiotic' gut-derived products observed in cardiovascular diseases, cancer, inflammatory bowel disease, metabolic diseases including non-alcoholic steatohepatitis and autoimmune disorders such as multiple sclerosis. The increased production of dysbiotic gut microbial products, including trimethylamine, hydrogen sulphide, products of amino acid metabolism such as p-Cresyl sulphate and phenylacetic acid, and secondary bile acids such as deoxycholic acid, is commonly observed across multiple diseases. The simultaneous increased production of dysbiotic metabolites with the impaired production of beneficial metabolites, commonly associated with a modern lifestyle, may partially explain the high prevalence of inflammatory diseases in western countries.

Transmembrane protein 117 knockdown protects against angiotensin-II-induced cardiac hypertrophy

Mitochondrial dysfunction plays a critical role in the pathogenesis of pathological cardiac hypertrophy. Transmembrane protein 117 modulate mitochondrial membrane potential that may be involved in the regulation of oxidative stress and mitochondrial function. However, its role in the development of angiotensin II (Ang-II)-induced cardiac hypertrophy is unclear. Cardiac-specific TMEM117-knockout and control mice were subjected to cardiac hypertrophy induced by Ang-II infusion. Small-interfering RNAs against TMEM117 or adenovirus-based plasmids encoding TMEM117 were delivered into left ventricles of mice or incubated with neonatal murine ventricular myocytes (NMVMs) before Ang-II stimulation. We found that TMEM117 was upregulated in hypertrophic hearts and cardiomyocytes and TMEM117 deficiency attenuated Ang-II-induced cardiac hypertrophy in vivo. Consistently, the in vitro data demonstrated that Ang-II-induced cardiomyocyte hypertrophy significantly alleviated by TMEM117 knockdown. Conversely, overexpression of TMEM117 exacerbated cardiac hypertrophy and dysfunction. An Ang II-induced increase in cardiac (cardiomyocyte) oxidative stress was alleviated by cardiac-specific knockout (knockdown) of TMEM117 and was worsened by TMEM117 supplementation (overexpression). In addition, TMEM117 knockout decreased endoplasmic reticulum stress induced by Ang-II, which was reversed by TMEM117 supplementation. Furthermore, TMEM117 deficiency mitigated mitochondrial injury in hypertrophic hearts and cardiomyocyte, which was abolished by TMEM117 supplementation (overexpression). Taken together, these findings suggest that upregulation of TMEM117 contributes to the development of cardiac hypertrophy and the downregulation of TMEM117 may be a new therapeutic strategy for the prevention and treatment of cardiac hypertrophy.

Dietary Patterns, Gut Microbiota Remodeling, and Cardiometabolic Disease

The cardiovascular and metabolic disorders, collectively known as cardiometabolic disease (CMD), are high morbidity and mortality pathologies associated with lower quality of life and increasing health-care costs. The influence of the gut microbiota (GM) in dictating the interpersonal variability in CMD susceptibility, progression and treatment response is beginning to be deciphered, as is the mutualistic relation established between the GM and diet. In particular, dietary factors emerge as pivotal determinants shaping the architecture and function of resident microorganisms in the human gut. In turn, intestinal microbes influence the absorption, metabolism, and storage of ingested nutrients, with potentially profound effects on host physiology. Herein, we present an updated overview on major effects of dietary components on the GM, highlighting the beneficial and detrimental consequences of diet-microbiota crosstalk in the setting of CMD. We also discuss the promises and challenges of integrating microbiome data in dietary planning aimed at restraining CMD onset and progression with a more personalized nutritional approach.

DEHP exposure elevated cardiovascular risk in obese mice by disturbing the arachidonic acid metabolism of gut microbiota

Phthalate esters (PAEs) are one of the significant classes of emerging contaminants that are increasingly detected in environmental and human samples. Nevertheless, the current toxicity studies rarely report how PAEs affect the cardiovascular system, especially in obese individuals. In this study, diet-induced obese mice and corresponding normal mice were exposed to di(2-ethylhexyl) phthalate (DEHP) by oral gavage at environmentally relevant concentrations and key characteristics of cardiovascular risk were examined. The 16S rRNA and high-resolution mass spectrometry were used to investigate the alterations in the gut microbial profile and metabolic homeostasis. The results indicated that the cardiovascular system of fat individuals was more susceptible to DEHP exposure than mice in the lean group. 16S rRNA-based profiling and correlation analysis collectively suggested DEHP-induced gut microbial remodeling in fed a high-fat diet mice, represented by the abundance of the genus Faecalibaculum. Using metagenomic approaches, Faecalibaculum rodentium was identified as the top-ranked candidate bacterium. Additionally, metabolomics data revealed that DEHP exposure altered the gut metabolic homeostasis of arachidonic acid (AA), which is associated with adverse cardiovascular events. Finally, cultures of Faecalibaculum rodentium were treated with AA in vitro to verify the role of Faecalibaculum rodentium in altering AA metabolism. Our findings provide novel insights into DEHP exposure induced cardiovascular damage in obese individuals and suggest that AA could be used as a potential modulator of gut microbiota to prevent related diseases.

Gut-muscle axis and sepsis-induced myopathy: The potential role of gut microbiota

Sepsis is described as an immune response disorder of the host to infection in which microorganisms play a non-negligible role. Most survivors of sepsis experience ICU-acquired weakness, also known as septic myopathy, characterized by skeletal muscle atrophy, weakness, and irreparable damage/regenerated or dysfunctional. The mechanism of sepsis-induced myopathy is currently unclear. It has been believed that this state is triggered by circulating pathogens and their related harmful factors, leading to impaired muscle metabolism. Sepsis and its resulting alterations in the intestinal microbiota are associated with sepsis-related organ dysfunction, including skeletal muscle wasting. There are also some studies on interventions targeting the flora, including fecal microbiota transplants, the addition of dietary fiber and probiotics in enteral feeding products, etc., aiming to improve sepsis-related myopathy. In this review, we critically assess the potential mechanisms and therapeutic prospects of intestinal flora in the development of septic myopathy.

The regulatory role of metabolic organ-secreted factors in the nonalcoholic fatty liver disease and cardiovascular disease

Nonalcoholic fatty liver disease (NAFLD) is a chronic metabolic disease characterized by an excessive accumulation of fat in the liver, which is becoming a major global health problem, affecting about a quarter of the population. In the past decade, mounting studies have found that 25%-40% of NAFLD patients have cardiovascular disease (CVD), and CVD is one of the leading causes of death in these subjects. However, it has not attracted enough awareness and emphasis from clinicians, and the underlying mechanisms of CVD in NAFLD patients remain unclear. Available research reveals that inflammation, insulin resistance, oxidative stress, and glucose and lipid metabolism disorders play indispensable roles in the pathogenesis of CVD in NAFLD. Notably, emerging evidence indicates that metabolic organ-secreted factors, including hepatokines, adipokines, cytokines, extracellular vesicles, and gut-derived factors, are also involved in the occurrence and development of metabolic disease and CVD. Nevertheless, few studies have focused on the role of metabolic organ-secreted factors in NAFLD and CVD. Therefore, in this review, we summarize the relationship between metabolic organ-secreted factors and NAFLD as well as CVD, which is beneficial for clinicians to comprehensive and detailed understanding of the association between both diseases and strengthen management to improve adverse cardiovascular prognosis and survival.

Sialic acid exacerbates gut dysbiosis-associated mastitis through the microbiota-gut-mammary axis by fueling gut microbiota disruption

BACKGROUND

Mastitis is one of the most severe diseases in humans and animals, especially on dairy farms. Mounting evidence indicates that gastrointestinal dysbiosis caused by induction of subacute ruminal acidosis (SARA) by high-grain diet consumption and low in dietary fiber is associated with mastitis initiation and development, however, the underlying mechanism remains unknown.

RESULTS

In the present study, we found that cows with SARA-associated mastitis have altered metabolic profiles in the rumen, with increased sialic acids level in particular. Consumption of sialic acid (SA) in antibiotic-treated mice, but not healthy mice, induced marked mastitis. SA treatment of antibiotic-treated mice also induced mucosal and systemic inflammatory responses, as evidenced by increased colon and liver injuries and several inflammatory markers. In addition, gut dysbiosis caused by antibiotic impaired gut barrier integrity, which was aggravated by SA treatment. SA potentiated serum LPS level caused by antibiotic treatment, leading to increased activation of the TLR4-NF-κB/NLRP3 pathways in the mammary gland and colon. Moreover, SA facilitated gut dysbiosis caused by antibiotic, and especially enhanced Enterobacteriaceae and Akkermansiaceae, which correlated with mastitis parameters. Fecal microbiota transplantation from SA-antibiotic-treated mice mimicked mastitis in recipient mice. In vitro experiments showed that SA prompted Escherichia coli growth and virulence gene expression, leading to higher proinflammatory cytokine production in macrophages. Targeting the inhibition of Enterobacteriaceae by sodium tungstate or treating with the commensal Lactobacillus reuteri alleviated SA-facilitated mastitis. In addition, SARA cows had distinct ruminal microbial structure by the enrichment of SA-utilizing opportunistic pathogenic Moraxellaceae and the depletion of SA-utilizing commensal Prevotellaceae. Treating mice with the specific sialidase inhibitor zanamivir reduced SA production and Moraxellaceae abundance, and improved mastitis in mice caused by ruminal microbiota transplantation from cows with SARA-associated mastitis.

CONCLUSIONS

This study, for the first time, indicates that SA aggravates gut dysbiosis-induced mastitis by promoting gut microbiota disturbance and is regulated by commensal bacteria, indicating the important role of the microbiota-gut-mammary axis in mastitis pathogenesis and suggesting a potential strategy for mastitis intervention based on gut metabolism regulation. Video Abstract.

Diabetic vascular diseases: molecular mechanisms and therapeutic strategies

Vascular complications of diabetes pose a severe threat to human health. Prevention and treatment protocols based on a single vascular complication are no longer suitable for the long-term management of patients with diabetes. Diabetic panvascular disease (DPD) is a clinical syndrome in which vessels of various sizes, including macrovessels and microvessels in the cardiac, cerebral, renal, ophthalmic, and peripheral systems of patients with diabetes, develop atherosclerosis as a common pathology. Pathological manifestations of DPDs usually manifest macrovascular atherosclerosis, as well as microvascular endothelial function impairment, basement membrane thickening, and microthrombosis. Cardiac, cerebral, and peripheral microangiopathy coexist with microangiopathy, while renal and retinal are predominantly microangiopathic. The following associations exist between DPDs: numerous similar molecular mechanisms, and risk-predictive relationships between diseases. Aggressive glycemic control combined with early comprehensive vascular intervention is the key to prevention and treatment. In addition to the widely recommended metformin, glucagon-like peptide-1 agonist, and sodium-glucose cotransporter-2 inhibitors, for the latest molecular mechanisms, aldose reductase inhibitors, peroxisome proliferator-activated receptor-γ agonizts, glucokinases agonizts, mitochondrial energy modulators, etc. are under active development. DPDs are proposed for patients to obtain more systematic clinical care requires a comprehensive diabetes care center focusing on panvascular diseases. This would leverage the advantages of a cross-disciplinary approach to achieve better integration of the pathogenesis and therapeutic evidence. Such a strategy would confer more clinical benefits to patients and promote the comprehensive development of DPD as a discipline.

Dysregulated amino acid metabolism in heart failure: role of gut microbiome

PURPOSE OF REVIEW

The importance of amino acid metabolism in heart failure has often been overlooked, especially in advanced stages. Metabolism of dietary compounds by gut microbiota generates a wide range of metabolites that can directly or indirectly modulate end-organ functions in their hosts. Herein, we describe recently discovered mechanistic links between various gut microbial metabolic pathways of amino acids and their derivatives in the pathophysiology of heart failure.

RECENT FINDINGS

Growing evidence points to incremental prognostic value in amino acid profiling in patients with heart failure. Reducing branched-chain amino acid levels in the failing heart may have a cardioprotective role. Gut microbiome-related amino acid, including amino acid supplementation, dietary interventions, or microbial enzyme inhibition, can be targeted to modify cardiovascular risks.

SUMMARY

Interplay between the gut microbiome and amino acid metabolism may contribute to disease progression in heart failure. Further investigations are warranted to uncover opportunities for intervention.

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.

Gut microbiome and metabolites, the future direction of diagnosis and treatment of atherosclerosis?

Over the past few decades, the treatment of atherosclerotic cardiovascular disease has mainly been through an LDL lowering strategy and treatments targeting other traditional risk factors for atherosclerosis, which has significantly reduced cardiovascular mortality. However, the overall benefit of targeting these risk factors has stagnated, and the discovery of new therapeutic targets for atherosclerosis remains a challenge. Accumulating evidence from clinical and animal experiments has revealed that the gut microbiome play a significant role in human health and disease, including cardiovascular diseases. The gut microbiome contribute to host health and disease through microbial composition and function. The gut microbiome function like an endocrine organ by generating bioactive metabolites that can impact atherosclerosis. In this review, we describe two gut microbial metabolites/pathways by which the gut affects atherosclerotic cardiovascular disease. On the one hand, we discuss the effects of trimethylamine oxide (TMAO), bile acids and aromatic amino acid metabolites on the development of atherosclerosis, and the protective effects of beneficial metabolites short chain amino acids and polyamines on atherosclerosis. On the other hand, we discuss novel therapeutic strategies for directly targeting gut microbial metabolites to improve cardiovascular outcomes. Reducing gut-derived TMAO levels and interfering with the bile acid receptor farnesoid X receptor (FXR) are new therapeutic strategies for atherosclerotic disease. Enzymes and receptors in gut microbiota metabolic pathways are potential new drug targets. We need solid insight into these underlying mechanisms to pave the way for therapeutic strategies targeting gut microbial metabolites/pathways for atherosclerotic cardiovascular disease.

Role of the Gut Microbiome in Skeletal Muscle Physiology and Pathophysiology

PURPOSE OF REVIEW

This review aims to summarize the recent findings about the contribution of the gut microbiome to muscle pathophysiology and discuss molecular pathways that may be involved in such process. Related findings in the context of cancer cachexia are outlined.

RECENT FINDINGS

Many bacterial metabolites have been reported to exert a beneficial or detrimental impact on muscle physiology. Most of the evidence concentrates on short-chain fatty acids (SCFAs), with an emerging role for bile acids, bacterial amino acid metabolites (bAAms), and bacterial polyphenol metabolites. Other molecular players worth considering include cytokines, hormones, lipopolysaccharides, and quorum sensing molecules. The current literature clearly establishes the ability for the gut microbiome to modulate muscle function and mass. The understanding of the mechanisms underlying this gut-muscle axis may lead to the delivery of novel therapeutic tools to tackle muscle wasting in cancer cachexia, chronic kidney disease, liver fibrosis, and age-related sarcopenia.

The Impact of Sleep Disturbance on Gut Microbiota, Atrial Substrate, and Atrial Fibrillation Inducibility in Mice: A Multi-Omics Analysis

This study examined the effect of sleep disturbance on gut microbiota (GM), atrial substrate, and atrial fibrillation (AF) inducibility. C57BL/6 mice were subjected to six weeks of sleep deprivation (SD) using the method of modified multiple-platform. Transesophageal burst pacing was performed to evaluate AF inducibility. Feces, plasma, and an atrium were collected and analyzed by 16s rRNA sequencing, liquid chromatography−mass spectrometry (LC-MS)-based metabolome, histological studies, and transcriptome. Higher AF inducibility (2/30 of control vs. 15/30 of SD, p = 0.001) and longer AF duration (p < 0.001), concomitant with aggravated fibrosis, collagen, and lipid accumulation, were seen in the SD mice compared to control mice. Meanwhile, elevated alpha diversity, higher abundance of Flavonifractor, Ruminococcus, and Alloprevotella, as well as imbalanced functional pathways, were observed in the gut of SD mice. Moreover, the global patterns for the plasma metabolome were altered, e.g., the decreased butanoate metabolism intermediates in SD mice. In addition, disrupted metabolic homeostasis in the SD atrium, such as fatty acid metabolism, was analyzed by the transcriptome. These results demonstrated that the crosstalk between GM and atrial metabolism might be a promising target for SD-mediated AF susceptibility.

The role of the gut microbiota in health and cardiovascular diseases

The gut microbiota is critical to human health, such as digesting nutrients, forming the intestinal epithelial barrier, regulating immune function, producing vitamins and hormones, and producing metabolites to interact with the host. Meanwhile, increasing evidence indicates that the gut microbiota has a strong correlation with the occurrence, progression and treatment of cardiovascular diseases (CVDs). In patients with CVDs and corresponding risk factors, the composition and ratio of gut microbiota have significant differences compared with their healthy counterparts. Therefore, gut microbiota dysbiosis, gut microbiota-generated metabolites, and the related signaling pathway may serve as explanations for some of the mechanisms about the occurrence and development of CVDs. Several studies have also demonstrated that many traditional and latest therapeutic treatments of CVDs are associated with the gut microbiota and its generated metabolites and related signaling pathways. Given that information, we summarized the latest advances in the current research regarding the effect of gut microbiota on health, the main cardiovascular risk factors, and CVDs, highlighted the roles and mechanisms of several metabolites, and introduced corresponding promising treatments for CVDs regarding the gut microbiota. Therefore, this review mainly focuses on exploring the role of gut microbiota related metabolites and their therapeutic potential in CVDs, which may eventually provide better solutions in the development of therapeutic treatment as well as the prevention of CVDs.

Trimethyllysine, a trimethylamine N-oxide precursor, predicts the presence, severity, and prognosis of heart failure

Background and aims

Intestinal flora metabolites are associated with cardiovascular (CV) diseases including heart failure (HF). The carnitine precursor trimethyllysine (TML), which participates in the generation of the atherogenic-related metabolite trimethylamine N-oxide (TMAO), was found to be related to poor prognosis in patients with CV diseases. The aim of the present study was to examine the relationship between TML and stable chronic HF.

Methods and results

In total, 956 subjects including 471 stable chronic HF and 485 non-HF patients were enrolled in the present cohort study and subjects with stable HF were followed up for 2.0 ± 1.1 years. Serum levels of TML and TMAO were measured by liquid chromatography mass spectrometry in tandem. TML levels were significantly elevated in patients with HF compared with non-HF patients and were positively correlated with N-terminal pro-brain natriuretic peptide (NTproBNP) levels (r = 0.448, P < 0.001). TML was associated with the presence of HF after adjusting for age, sex, complications, traditional clinical factors, and TMAO (tertile 3 (T3), adjusted odds ratio (OR) 1.93, 95% confidence interval (CI) 1.19–3.13, and P = 0.007). In patients with HF, increased TML levels were associated with a composite endpoint of CV death and HF hospitalization during follow-up (T3, adjusted hazard ratio (HR) 1.93, 95% CI 1.27–2.93, and P = 0.002). Increased TML levels indicated a higher risk of CV death, re-hospitalization, and all-cause mortality.

Conclusion

Serum TML levels were associated with the presence and severity of HF in all subjects. High levels of TML can indicate complications and poor prognosis in HF patients.

Protective Effect of Shengmaiyin in Myocardial Hypertrophy-Induced Rats: A Genomic Analysis by 16S rDNA

Background

The gut-cardiac axis theory provides new insights into the complex mechanisms of cardiac hypertrophy and provides new therapeutic targets. Cardiac hypertrophy is a risk factor for heart failure. Shengmaiyin (SMY) is a traditional Chinese medicine formula with clear effects in the treatment and prevention of cardiac hypertrophy, but the mechanism by which it improves cardiac hypertrophy is still unclear. Therefore, this study aimed to investigate the protective effect and mechanism of SMY on isoproterenol (ISO)-induced myocardial hypertrophy in rats.

Methods

First, various pharmacodynamic methods were used to evaluate the therapeutic effect of SMY on ISO-induced myocardial hypertrophy in rats. Then, 16S rDNA amplicon sequencing technology was used to study the effect of SMY on the intestinal flora of rats with myocardial hypertrophy. Finally, the mechanism underlying the effect of SMY on cardiac hypertrophy was predicted by bioinformatics network analysis and verified by Western blotting.

Results

SMY increased ejection fraction (EF%) and left ventricular fractional shortening (FS%), ameliorated myocardial cell injury and fibrosis, regulated blood lipids and energy metabolism, and decreased cardiac hypertrophy marker gene expression. The gut microbiota of ISO-induced myocardial hypertrophy rats were significantly changed, while SMY effectively ameliorated the dysbiosis of the intestinal flora in rats with myocardial hypertrophy, especially Prevotella 9, Lactobacillus, and Clostridium. Mechanistic studies have shown that the anticardiac hypertrophy effect of SMY is related to the inhibition of the expression of HIF1α/PPAR signalling pathway-related proteins.

Conclusion

SMY significantly improves cardiac function, relieves myocardial cell fibrosis and necrosis, resists cardiac hypertrophy, improves blood lipid metabolism and energy metabolism, regulates intestinal microbial disturbance, and protects the heart.

Diet- and microbiota-related metabolite, 5-aminovaleric acid betaine (5-AVAB), in health and disease

5-Aminovaleric acid betaine (5-AVAB) is a trimethylated compound associated with the gut microbiota, potentially produced endogenously, and related to the dietary intake of certain foods such as whole grains. 5-AVAB accumulates within the metabolically active tissues and has been typically found in higher concentrations in the heart, muscle, and brown adipose tissue. Furthermore, 5-AVAB has been associated with positive health effects such as fetal brain development, insulin secretion, and reduced cancer risk. However, it also has been linked with some negative health outcomes such as cardiovascular disease and fatty liver disease. At the cellular level, 5-AVAB can influence cellular energy metabolism by reducing β-oxidation of fatty acids. This review will focus on the metabolic role of 5-AVAB with respect to both physiology and pathology. Moreover, the analytics and origin of 5-AVAB and related compounds will be reviewed.