Targeting the gut microbiota with inulin-type fructans: preclinical demonstration of a novel approach in the management of endothelial dysfunction

Gut Microbial Metabolite Imidazole Propionate Impairs Endothelial Cell Function and Promotes the Development of Atherosclerosis

BACKGROUND

The microbially produced amino acid-derived metabolite imidazole propionate (ImP) contributes to the pathogenesis of type 2 diabetes. However, the effects of ImP on endothelial cell (EC) physiology and its role in atherosclerotic coronary artery disease are unknown. Using both human and animal model studies, we investigated the potential contributory role of ImP in the development of atherosclerosis.

METHODS

Plasma levels of ImP were measured in patients undergoing elective cardiac angiography (n=831) by ultra-high performance liquid chromatography coupled to tandem mass spectrometry. Odds ratios and corresponding 95% confidence intervals for coronary artery disease were calculated based on the ImP quartiles using both univariable and multivariable logistic regression models. The effects of ImP on functional properties of ECs were assessed using HAECs (human aortic endothelial cells). In a mouse model of carotid artery injury, the impact of ImP on vascular regeneration was examined. Additionally, atheroprone Apoe-/- mice fed a high-fat diet were treated with and without ImP (800 µg), and aortic atherosclerotic lesion area was evaluated after 12 weeks. Next-generation sequencing, Western blot analysis, small interfering RNA-based gene knockdown, and tamoxifen-inducible Cre-loxP experiments were performed to investigate ImP-mediated molecular mechanisms.

RESULTS

Plasma ImP levels in subjects undergoing cardiac evaluation were associated with increased risk of prevalent coronary artery disease. We found that ImP dose dependently impaired migratory and angiogenic properties of human ECs and promoted an increased inflammatory response. Long-term exposure to ImP compromised the repair potential of the endothelium after an arterial insult. In atheroprone Apoe-/- (apolipoprotein E-/-) mice, ImP increased atherosclerotic lesion size. Mechanistically, ImP attenuated insulin receptor signaling by suppressing the PI3K (phosphoinositide 3-kinase)/AKT pathway leading to sustained activation of the FOXO1 (forkhead box protein O1) transcription factor. Genetic inactivation of endothelial FOXO1 signaling in ImP-treated mice enhanced the angiogenic activity and preserved the vascular repair capacity of ECs after carotid injury.

CONCLUSIONS

Our findings reveal a hitherto unknown role of the microbially produced histidine-derived metabolite ImP in endothelial dysfunction and atherosclerosis, suggesting that ImP metabolism is a potential therapeutic target in atherosclerotic cardiovascular disease.

Monospecies Bacteria-Induced Chronic Apical Periodontitis Triggers the Aortic Inflammatory Response Via Modulation of Systemic Inflammation and Lipid Metabolism

Cardiovascular disease (CVD) is the leading cause of death worldwide and has been confirmed to be associated with a common oral bacterial infection-chronic apical periodontitis (CAP). However, the detailed mechanisms remain controversial. CAP can potentially alter systemic inflammation, lipid metabolism, and gut microbiota, all of which contribute to the progression of the aortic inflammatory response. This study aimed to explore the differential effects between Enterococcus faecalis and Porphyromonas gingivalis-CAP on the aortic inflammatory response, which focused on changes in systemic inflammation, lipid metabolism, and gut microbiota, to explore potential mechanisms linking oral disease to CVD. Our results showed P. gingivalis-CAP could activate more serious aortic inflammatory cytokine micro RNA expression (TNF-α, MCP-1, and ICAM-1) than E. faecalis-CAP by promoting higher serum inflammation (TNF-α, IL-6, IL-1α, and MCP-1) and lipid (low-density lipoprotein cholesterol and total cholesterol) levels. Simultaneously, there was no significant change in gut microbiota between them. Furthermore, all serum inflammatory cytokines showed substantial correlations with aortic inflammatory cytokine micro RNA expression, and certain serum lipid indicators showed significant correlations, but only 2 gut microorganisms (Ruminococcaceae and Prevotellaceae) showed significant correlations. The combined results suggest that CAP might activate the aortic inflammatory response in association with changes in the 3 potential mechanisms. However, the promotion of gut microbiota might be relatively weak. Using experimental CAP induced by specific bacteria, in which bacteria are sequestered in the medullary cavity, avoids the direct influence of blood or intestinal pathways and provides new perspectives for studying the mechanism of CVD associated with oral disease. Overall, these findings suggest that CAP may exacerbate systemic inflammation and serum lipid levels in patients with CVD, highlighting the importance of educating such patients on oral hygiene.

Protective Effect of Dietary Fiber on Blood Pressure and Vascular Dysfunction Through Regulation of Sympathetic Tone and Immune Response in Genetic Hypertension

The mechanisms underlying the antihypertensive effect of dietary fibers remain poorly understood. This study investigates whether dietary fiber supplementation can prevent cardiovascular damage and high blood pressure in a genetic model of neurogenic hypertension. Six-week-old male spontaneously hypertensive rats (SHR) and their respective normotensive control, Wistar Kyoto rats (WKY), were divided into four groups: Untreated WKY, untreated SHR, SHR treated with resistant starch (SHR + RS), and SHR treated with inulin-type fructans (SHR + ITF) for 12 weeks. Additionally, a faecal microbiota transplantation (FMT) experiment was conducted, transferring faecal content from treated SHR donors to recipient SHRs. A diet rich in RS fiber reduced vascular oxidative stress, inflammation, and high blood pressure. These protective effects were associated with a reshaped gut microbiota, leading to increased short-chain fatty acid production, reduced endotoxemia, decreased sympathetic activity, and a restored balance between Th17 and Treg lymphocytes in mesenteric lymph nodes and aorta. Elevated plasma levels of acetate and butyrate in the SHR + RS group correlated with increased expression of aortic GPR41, GRP43 and PPARδ. Conversely, ITF treatment failed to prevent hypertension or endothelial dysfunction in SHR. FMT from the SHR + RS group to recipient SHR partially replicated these beneficial effects. This study highlights the antihypertensive benefits of dietary insoluble RS fiber, which are attributed to enhanced short-chain fatty acids production in the gut. This leads to improved gut permeability, reduced sympathetic tone, and diminished vascular T-cell accumulation. Therefore, dietary interventions with RS fiber may offer promising therapeutic strategies for preventing hypertension.

Beyond the gut: Unraveling the multifaceted influence of microbiome on cardiovascular health

Cardiovascular disease is one of the leading causes of death worldwide. Even while receiving adequate pharmacological treatment for their hypertension, people are nonetheless at greater risk for cardiovascular disease. There is growing evidence that the gut microbiota may have major positive and negative effects on blood pressure and illnesses related with it as more study into this topic is conducted. Trimethylamine n-oxide (TMAO) and short-chain fatty acids (SCFA) are two major by-products of the gut microbiota. TMAO is involved in the formation of other coronary artery diseases, including atherosclerosis and hypertension, while SCFAs play an important role in controlling blood pressure. Numerous investigations have confirmed the established link between dietary salt intake and hypertension. Reducing sodium in the diet is linked to lower rates of cardiovascular disease morbidity and mortality as well as lower rates of blood pressure and hypertension. In both human and animal research, high salt diets increase local and systemic tissue inflammation and compromise gut architecture. Given that the gut microbiota constantly interacts with the immune system and is required for the correct maturation of immune cells, it is scientifically conceivable that it mediates the inflammatory response. This review highlights the therapeutic possibilities for focusing on intestinal microbiomes as well as the potential functions of the gut microbiota and its metabolites in the development of hypertension.

Pasteurized Akkermansia muciniphila Ameliorates Preeclampsia in Mice by Enhancing Gut Barrier Integrity, Improving Endothelial Function, and Modulating Gut Metabolic Dysregulation

Preeclampsia (PE) is a serious complication of pregnancy linked to endothelial dysfunction and an imbalance in the gut microbiota. While Akkermansia muciniphila (AKK) has shown promise in alleviating PE symptoms, the use of live bacteria raises safety concerns. This study explored the potential of pasteurized A. muciniphila (pAKK) as a safer alternative for treating PE, focusing on its effects on endothelial function and metabolic regulation. A PE mouse model was induced via the nitric oxide synthase inhibitor L-NAME, followed by treatment with either pAKK or live AKK. Fecal metabolomic profiling was performed via liquid chromatography-tandem mass spectrometry (LC-MS/MS), and in vivo and in vitro experiments were used to assess the effects of pAKK on endothelial function and metabolic pathways. pAKK exhibited therapeutic effects comparable to those of live AKK in improving L-NAME-induced PE-like phenotypes in mice, including enhanced gut barrier function and reduced endotoxemia. pAKK also promoted placental angiogenesis by restoring endothelial nitric oxide synthase (eNOS) activity and nitric oxide (NO) production. The in vitro experiments further confirmed that pAKK alleviated L-NAME-induced NO reduction and endothelial dysfunction in human umbilical vein endothelial cells (HUVECs). Metabolomic analysis revealed that both pAKK and live AKK reversed metabolic disturbances in PE by modulating key metabolites and pathways related to unsaturated fatty acid biosynthesis, folate, and linoleic acid metabolism. As a postbiotic, pAKK may support existing treatments for preeclampsia by improving gut barrier function, restoring endothelial function, and regulating metabolic dysregulation, offering a safer alternative to live bacteria. These findings highlight the potential clinical value of pAKK as an adjunctive therapy in managing PE.

The Role of Gut Microbiota Modification in Nonalcoholic Fatty Liver Disease Treatment Strategies

One of the most common chronic liver diseases is nonalcoholic fatty liver disease (NAFLD), which affects many people around the world. Gut microbiota (GM) dysbiosis seems to be an influential factor in the pathophysiology of NAFLD because changes in GM lead to fundamental changes in host metabolism. Therefore, the study of the effect of dysbiosis on the pathogenicity of NAFLD is important. European clinical guidelines state that the best advice for people with NAFLD is to lose weight and improve their lifestyle, but only 40% of people can achieve this goal. Accordingly, it is necessary to provide new treatment approaches for prevention and treatment. In addition to dietary interventions and lifestyle modifications, GM modification-based therapies are of interest. These therapies include probiotics, synbiotics, fecal microbiota transplantation (FMT), and next-generation probiotics. All of these treatments have had promising results in animal studies, and it can be imagined that acceptable results will be obtained in human studies as well. However, further investigations are required to generalize the outcomes of animal studies to humans.

Probiotics-role in alleviating the impact of alcohol liver disease and alcohol deaddiction: a systematic review

Background

There are few efficient treatment options for alcohol addiction, which continues to be a serious public health concern. The possible contribution of gut microbiota to the onset and progression of alcohol addiction has been brought to light by recent studies. Probiotics have become a cutting-edge intervention in the treatment of alcohol consumption disorder because of its favorable effects on gut health. The purpose of this systematic review is to assess the body of research on the advantages of probiotics in treating alcoholism and associated neuroinflammatory conditions.

Methods

To find pertinent research published from January 2012 to 2023, a thorough search of electronic databases, including PubMed, Scopus, Google Scholar and Web of Science, was carried out. Included were studies looking at how probiotics affect neuroinflammation, gut- brain axis regulation, alcohol addiction, and related behaviors.

Findings

Several investigations have shown how beneficial probiotics are in reducing systemic inflammation and alcoholic liver disease (ALD). Probiotic treatments successfully corrected the imbalance of microbiota, decreased intestinal permeability, and stopped the passage of bacterial constituents such lipopolysaccharides (LPS) into the bloodstream. Additionally, probiotics helped to regulate neurotransmitter pathways, especially those connected to GABA, glutamate, and dopamine, which are intimately linked to behaviors related to addiction. Furthermore, it was shown that probiotics altered the expression of neurotransmitter signaling and dopamine receptors.

Conclusion

There is strong evidence from this systematic study that probiotics have potential advantages in treating alcohol addiction. The potential of probiotic therapies is demonstrated by the way they modulate important neurotransmitter pathways implicated in addiction, decrease neuroinflammation, and restore the balance of gut flora. To fully investigate the therapeutic potential of probiotics in treating alcohol addiction and enhancing the general wellbeing of those afflicted by this condition, more research is necessary.

Oral Supplementation with the Short-Chain Fatty Acid Acetate Ameliorates Age-Related Arterial Dysfunction in Mice

Adverse changes in the gut microbiome with aging are an emerging mediator of arterial dysfunction, which contributes to cardiovascular disease (CVD) development. We investigated the therapeutic potential of enhancing the bioavailability of gut-derived short-chain fatty acids (SCFAs; produced from dietary fiber) for improving age-related arterial dysfunction. We performed gut microbial whole-genome sequencing in young (3 months) versus old (24 months) male C57BL/6N mice to explore changes in bacterial taxonomic abundance and functional pathways with aging and relations to arterial function. We then supplemented young and old mice with the SCFA acetate in drinking water versus controls and versus a high-fiber diet for 8-10 weeks to test the effects of these interventions on vascular function and explore potential mechanisms. Of the various differences in the gut microbiomes of old mice, lower SCFA-producing capacity (taxonomic abundance and functional pathways) stood out as a key feature related to worse arterial function after adjusting for age. Acetate supplementation and a high-fiber diet reversed ~30% of the age-related increase in aortic pulse wave velocity (stiffness) and fully restored carotid artery endothelium-dependent dilation (endothelial function) to young levels. Acetate and a high-fiber diet reduced age-related increases in systemic inflammation. We also found that improvements in endothelial function were likely mediated by suppressed early growth response-1 signaling using innovative siRNA-based knockdown in isolated arteries. There were no effects of the interventions in young mice. Acetate supplementation was comparably effective for ameliorating arterial dysfunction with aging as a high-fiber diet and thus shows promise for reducing CVD risk in older adults.

Applications of polysaccharides in enzyme-triggered oral colon-specific drug delivery systems: A review

Enzyme-triggered oral colon-specific drug delivery system (EtOCDDS1) can withstand the harsh stomach and small intestine environments, releasing encapsulated drugs selectively in the colon in response to colonic microflora, exerting local or systematic therapeutic effects. EtOCDDS boasts high colon targetability, enhanced drug bioavailability, and reduced systemic side effects. Polysaccharides are extensively used in enzyme-triggered oral colon-specific drug delivery systems, and its colon targetability has been widely confirmed, as their properties meet the demand of EtOCDDS. Polysaccharides, known for their high safety and excellent biocompatibility, feature modifiable structures. Some remain undigested in the stomach and small intestine, whether in their natural state or after modifications, and are exclusively broken down by colon-resident microbiota. Such characteristics make them ideal materials for EtOCDDS. This article reviews the design principles of EtOCDDS as well as commonly used polysaccharides and their characteristics, modifications, applications and specific mechanism for colon targeting. The article concludes by summarizing the limitations and potential of ETOCDDS to stimulate the development of innovative design approaches.

The gut microbiome as a modulator of arterial function and age-related arterial dysfunction

The arterial system is integral to the proper function of all other organs and tissues. Arterial function is impaired with aging, and arterial dysfunction contributes to the development of numerous age-related diseases, including cardiovascular diseases. The gut microbiome has emerged as an important regulator of both normal host physiological function and impairments in function with aging. The purpose of this review is to summarize more recently published literature demonstrating the role of the gut microbiome in supporting normal arterial development and function and in modulating arterial dysfunction with aging in the absence of overt disease. The gut microbiome can be altered due to a variety of exposures, including physiological aging processes. We explore mechanisms by which the gut microbiome may contribute to age-related arterial dysfunction, with a focus on changes in various gut microbiome-related compounds in circulation. In addition, we discuss how modulating circulating levels of these compounds may be a viable therapeutic approach for improving artery function with aging. Finally, we identify and discuss various experimental considerations and research gaps/areas of future research.

Conserved signatures of the canine faecal microbiome are associated with metronidazole treatment and recovery

Antibiotic resistance is recognised as one of the biggest global threats to human and animal health. Understanding the influence of antibiotics on the canine microbiome is important to know the potential mid-to-long term effects on dysbiosis and mitigate side-effects such as antibiotic-associated diarrhoea. In this study, metronidazole was prescribed to 22 dogs for suspected giardiasis after exhibiting gastrointestinal symptoms such as diarrhoea and/or vomiting. Faecal samples were collected before, during seven days of treatment, and six months post-cessation. Faecal microbiota was assessed with 16S rRNA sequencing. Shannon diversity was reduced for up to three days after the treatment ended, and an altered community persisted for four to six weeks. All dogs recovered to a similar microbiome composition as pre-treatment. Immediately after receiving metronidazole, an increase in the relative abundance of the genera Lactobacillus, Bifidobacterium, and Enterococcus was observed. This may be due to antibiotic resistance commonly exhibited by these organisms. One-to-two weeks post-cessation, several other genera that were sensitive to the antibiotic recovered in abundances, with taxa belonging to the Erysipelotrichaceae family particularly driving composition change. Many of the bacteria initially reduced were associated with carbohydrate fermentation. This suggests scope exists to explore interventions to augment gastrointestinal health and support the re-establishment of the microbiome.

Inulin-type fructans with different degrees of polymerization improve insulin resistance, metabolic parameters, and hormonal status in overweight and obese women with polycystic ovary syndrome: A randomized double-blind, placebo-controlled clinical trial

Polycystic ovary syndrome (PCOS) is associated with reproductive disorders and adverse cardiometabolic risk factors that can negatively impact the general health of women. Inulin-type fructans (ITFs) are proposed to beneficially affect risk factors associated with metabolic disorders. Whether ITFs can help with the management of PCOS by modifying insulin resistance (IR) and androgen levels has not yet been explored. The aim of this study was to investigate the effects of ITFs with different degrees of polymerization on insulin resistance, blood lipids, anthropometric measures, and hormonal status in overweight and obese women with PCOS. In a randomized double-blind placebo-controlled trial, seventy-five women with PCOS aged 18-40 years old were randomly assigned to receive 10 g/day of high-performance inulin (HPI) or oligofructose-enriched inulin (OEI) or maltodextrin for 12 weeks. Biochemical and clinical outcomes were measured at baseline and after the intervention. Participants in the HPI and OEI groups experienced improvements in waist circumference, total testosterone, free androgen index, sex hormone-binding globulin, and triglycerides compared to the placebo group. Also, the number of women with irregular menses or oligomenorrhoea decreased significantly in both ITF groups. Participants in the HPI group reported lower body mass, fasting insulin, and HOMA-IR, as well as a higher quantitative insulin sensitivity check index. ITF supplementation, especially with long-chain ITFs, when given for 12 weeks may improve metabolic outcomes, androgen status and clinical manifestations in women with PCOS.

Targeting the Gut Microbiome to Treat Cardiometabolic Disease

PURPOSE OF REVIEW

Cardiometabolic diseases, which include obesity, type 2 diabetes, and cardiovascular diseases, constitute a worldwide health crisis of unparalleled proportions. The human gut microbiota has emerged as a prominent topic of inquiry in the search for novel treatment techniques. This review summarizes current research on the potential of addressing the gut microbiota to treat cardiometabolic disease.

RECENT FINDINGS

Recent studies have highlighted a complex link between the gut microbiota and host physiology, shedding light on the several processes through which gut microorganisms impact metabolic health, inflammation, and cardiovascular function. Furthermore, a growing corpus of research is available on microbiome-based therapies such as dietary interventions, probiotics, prebiotics, synbiotics, and fecal microbiota transplantation. These therapies show promise as methods for reshaping the gut microbiota and, as a result, improving cardiometabolic outcomes. However, hurdles remain, ranging from the intricacies of microbiome research to the necessity for tailored treatments that take individual microbial variations into consideration, emphasizing the significance of furthering research to bridge the gap between microbiome science and clinical practice. The gut microbiome is a beacon of hope for improving the management of cardiometabolic disease in the age of precision medicine, since its association with their pathophysiology is constantly being unraveled and strengthened. Available studies point to the potential of gut microbiome-based therapeutics, which remains to be tested in appropriately designed clinical trials. Further preclinical research is, however, essential to provide answers to the existing obstacles, with the ultimate goal of enhancing patient care.

Resolution of inflammation in chronic disease via restoration of the heat shock response (HSR)

Effective resolution of inflammation via the heat shock response (HSR) is pivotal in averting the transition to chronic inflammatory states. This transition characterizes a spectrum of debilitating conditions, including insulin resistance, obesity, type 2 diabetes, nonalcoholic fatty liver disease, and cardiovascular ailments. This manuscript explores a range of physiological, pharmacological, and nutraceutical interventions aimed at reinstating the HSR in the context of chronic low-grade inflammation, as well as protocols to assess the HSR. Monitoring the progression or suppression of the HSR in patients and laboratory animals offers predictive insights into the organism's capacity to combat chronic inflammation, as well as the impact of exercise and hyperthermic treatments (e.g., sauna or hot tub baths) on the HSR. Interestingly, a reciprocal correlation exists between the expression of HSR components in peripheral blood leukocytes (PBL) and the extent of local tissue proinflammatory activity in individuals afflicted by chronic inflammatory disorders. Therefore, the Heck index, contrasting extracellular 70 kDa family of heat shock proteins (HSP70) (proinflammatory) and intracellular HSP70 (anti-inflammatory) in PBL, serves as a valuable metric for HSR assessment. Our laboratory has also developed straightforward protocols for evaluating HSR by subjecting whole blood samples from both rodents and human volunteers to ex vivo heat challenges. Collectively, this discussion underscores the critical role of HSR disruption in the pathogenesis of chronic inflammatory states and emphasizes the significance of simple, cost-effective tools for clinical HSR assessment. This understanding is instrumental in the development of innovative strategies for preventing and managing chronic inflammatory diseases, which continue to exert a substantial global burden on morbidity and mortality.

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.

Akkermansia muciniphila and Alcohol-Related Liver Diseases. A Systematic Review

SCOPE

Akkermansia muciniphila (A. muciniphila) are Gram negative commensal bacteria, degrading mucin in the intestinal mucosa, modulating intestinal permeability and inflammation in the digestive tract, liver, and blood. Some components can promote the relative abundance of A. muciniphila in the gut microbiota, but lower levels of A. muciniphila are more commonly found in people with obesity, diabetes, metabolic syndromes, or inflammatory digestive diseases. Over-intake of ethanol can also induce a decrease of A. muciniphila, associated with dysregulation of microbial metabolite production, impaired intestinal permeability, induction of chronic inflammation, and production of cytokines.

METHODS AND RESULTS

Using a PRISMA search strategy, a review is performed on the bacteriological characteristics of A. muciniphila, the factors capable of modulating its relative abundance in the digestive tract and its probiotic use in alcohol-related liver diseases (alcoholic hepatitis, cirrhosis, hepatocellular carcinoma, hepatic transplantation, partial hepatectomy).

CONCLUSION

Several studies have shown that supplementation with A. muciniphila can improve ethanol-related hepatic pathologies, and highlight the interest in using this bacterial species as a probiotic.

Protective effect of microbiota-derived short chain fatty acids on vascular dysfunction in mice with systemic lupus erythematosus induced by toll like receptor 7 activation

Our objective was to investigate whether short-chain fatty acids (SCFAs), specifically acetate and butyrate, could prevent vascular dysfunction and elevated blood pressure (BP) in mice with systemic lupus erythematosus (SLE) induced by TLR7 activation using imiquimod (IMQ). Treatment with both SCFAs and dietary fibers rich in resistant starch (RS) or inulin-type fructans (ITF) effectively prevented the development of hypertension and cardiac hypertrophy. Additionally, these treatments improved aortic relaxation induced by acetylcholine and mitigated vascular oxidative stress. Acetate and butyrate treatments also contributed to the maintenance of colonic integrity, reduced endotoxemia, and decreased the proportion of helper T (Th)17 cells in mesenteric lymph nodes (MLNs), blood, and aorta in TLR7-induced SLE mice. The observed changes in MLNs were correlated with increased levels of GPR43 mRNA in mice treated with acetate and increased GPR41 levels along with decreased histone deacetylase (HDAC)- 3 levels in mice treated with butyrate. Notably, the effects attributed to acetate, but not butyrate, were nullified when co-administered with the GPR43 antagonist GLPG-0974. T cell priming and differentiation into Th17 cells in MLNs, as well as increased Th17 cell infiltration, were linked to aortic endothelial dysfunction and hypertension subsequent to the transfer of faecal microbiota from IMQ-treated mice to germ-free (GF) mice. These effects were counteracted in GF mice through treatment with either acetate or butyrate. To conclude, these findings underscore the potential of SCFA consumption in averting hypertension by restoring balance to the interplay between the gut, immune system, and vascular wall in SLE induced by TLR7 activation.

Targeting the gut microbiota with dietary fibers: a novel approach to prevent the development cardiovascular complications linked to systemic lupus erythematosus in a preclinical study

This study is to investigate whether dietary fiber intake prevents vascular and renal damage in a genetic mouse model of systemic lupus erythematosus (SLE), and the contribution of gut microbiota in the protective effects. Female NZBWF1 (SLE) mice were treated with resistant-starch (RS) or inulin-type fructans (ITF). In addition, inoculation of fecal microbiota from these experimental groups to recipient normotensive female C57Bl/6J germ-free (GF) mice was performed. Both fiber treatments, especially RS, prevented the development of hypertension, renal injury, improved the aortic relaxation induced by acetylcholine, and the vascular oxidative stress. RS and ITF treatments increased the proportion of acetate- and butyrate-producing bacteria, respectively, improved colonic inflammation and integrity, endotoxemia, and decreased helper T (Th)17 proportion in mesenteric lymph nodes (MLNs), blood, and aorta in SLE mice. However, disease activity (splenomegaly and anti-ds-DNA) was unaffected by both fibers. T cell priming and Th17 differentiation in MLNs and increased Th17 infiltration was linked to aortic endothelial dysfunction and hypertension after inoculation of fecal microbiota from SLE mice to GF mice, without changes in proteinuria and autoimmunity. All these effects were lower in GF mice after fecal inoculation from fiber-treated SLE mice. In conclusion, these findings support that fiber consumption prevented the development of hypertension by rebalancing of dysfunctional gut-immune system-vascular wall axis in SLE.

The correlation between gut microbiome and atrial fibrillation: pathophysiology and therapeutic perspectives

Regulation of gut microbiota and its impact on human health is the theme of intensive research. The incidence and prevalence of atrial fibrillation (AF) are continuously escalating as the global population ages and chronic disease survival rates increase; however, the mechanisms are not entirely clarified. It is gaining awareness that alterations in the assembly, structure, and dynamics of gut microbiota are intimately engaged in the AF progression. Owing to advancements in next-generation sequencing technologies and computational strategies, researchers can explore novel linkages with the genomes, transcriptomes, proteomes, and metabolomes through parallel meta-omics approaches, rendering a panoramic view of the culture-independent microbial investigation. In this review, we summarized the evidence for a bidirectional correlation between AF and the gut microbiome. Furthermore, we proposed the concept of "gut-immune-heart" axis and addressed the direct and indirect causal roots between the gut microbiome and AF. The intricate relationship was unveiled to generate innovative microbiota-based preventive and therapeutic interventions, which shed light on a definite direction for future experiments.

Modulation of the nitric oxide/cGMP pathway in cardiac contraction and relaxation: Potential role in heart failure treatment

Evidence exists that heart failure (HF) has an overall impact of 1-2 % in the global population being often associated with comorbidities that contribute to increased disease prevalence, hospitalization, and mortality. Recent advances in pharmacological approaches have significantly improved clinical outcomes for patients with vascular injury and HF. Nevertheless, there remains an unmet need to clarify the crucial role of nitric oxide/cyclic guanosine 3',5'-monophosphate (NO/cGMP) signalling in cardiac contraction and relaxation, to better identify the key mechanisms involved in the pathophysiology of myocardial dysfunction both with reduced (HFrEF) as well as preserved ejection fraction (HFpEF). Indeed, NO signalling plays a crucial role in cardiovascular homeostasis and its dysregulation induces a significant increase in oxidative and nitrosative stress, producing anatomical and physiological cardiac alterations that can lead to heart failure. The present review aims to examine the molecular mechanisms involved in the bioavailability of NO and its modulation of downstream pathways. In particular, we focus on the main therapeutic targets and emphasize the recent evidence of preclinical and clinical studies, describing the different emerging therapeutic strategies developed to counteract NO impaired signalling and cardiovascular disease (CVD) development.

Alterations of gut microbiome and metabolism induced by inulin associated with weight loss in obese female mice

Our previous work revealed the microbiota-dependent beneficial effects of inulin in obese male mice, but the effects in obese female mice were not determined. High-fat diet (HFD)-induced obese female mice were switched to normal diets and gavaged with normal saline or inulin for 10 weeks. Inulin supplementation significantly accelerated weight loss and reversed HFD-induced gut microbiota dysbiosis in obese female mice, and also reduced the ratio of Firmicutes/Bacteroidetes and enriched the abundance of norank_f_Muribaculaceae and Alistipes. In addition, 52 key serum metabolites were distinctly altered after inulin supplementation. Among them, andrographolide and monoacylglycerols (18:4) increased more than 9-fold and 14-fold, respectively, while phosphatidylcholine (PC) (18:1e/2:0), PC (20:1/20:2) and PC (19:1/19:1) decreased. In conclusion, gut microbiota and metabolites were closely associated with the beneficial effects of inulin in accelerating weight loss in obese female mice.

Gut vascular barrier in the pathogenesis and resolution of Crohn's disease: A novel link from origination to therapy

The gut vascular barrier (GVB) is the deepest layer of the gut barrier. It mainly comprised gut vascular endothelial cells, enteric glial cells, and pericytes. The GVB facilitates nutrient absorption and blocks bacterial translocation through its size-restricted permeability. Accumulating evidence suggests that dysfunction of this barrier correlates with several clinical pathologies including Crohn's disease (CD). Significant progress has been made to elucidate the mechanism of GVB dysfunction and to confirm the participation of disrupted GVB in the course of CD. However, further analyses are required to pinpoint the specific roles of GVB in CD pathogenesis. Many preclinical models and clinical trials have demonstrated that various agents are effective in protecting the GVB integrity and thus providing a potential CD treatment strategy. Through this review, we established a systemic understanding of the role of GVB in CD pathogenesis and provided novel insights for GVB-targeting strategies in CD treatment.

Electroacupuncture treatment ameliorates metabolic disorders in obese ZDF rats by regulating liver energy metabolism and gut microbiota

Metabolic disorders represent a major therapeutic challenge to public health worldwide due to their dramatically increasing prevalence. Acupuncture is widely used as adjuvant therapy for multiple metabolic diseases. However, detailed biological interpretation of the acupuncture stimulations is still limited. The gut and the liver are intrinsically connected and related to metabolic function. Microbial metabolites might affect the gut-liver axis through multiple mechanisms. Liver metabolomics and 16S rRNA sequencing were used to explore the specific mechanism of electroacupuncture in treating ZDF rats in this study. Electroacupuncture effectively improved glycolipid metabolism disorders of the ZDF rats. Histopathology confirmed that electroacupuncture improved diffuse hepatic steatosis and hepatocyte vacuolation, and promoted glycogen accumulation in the liver. The treatment significantly improved microbial diversity and richness and upregulated beneficial bacteria that maintain intestinal epithelial homeostasis and decreased bacteria with detrimental metabolic features on host metabolism. Liver metabolomics showed that the main effects of electroacupuncture include reducing the carbon flow and intermediate products in the TCA cycle, regulating the metabolism of various amino acids, and inhibiting hepatic glucose output and de novo lipogenesis. The gut-liver axis correlation analysis showed a strong correlation between the liver metabolites and the gut microbiota, especially allantoin and Adlercreutzia. Electroacupuncture treatment can improve abnormal energy metabolism by reducing oxidative stress, ectopic fat deposition, and altering metabolic fluxes. Our results will help us to further understand the specific mechanism of electroacupuncture in the treatment of metabolic diseases.

Helicobacter pylori infection selectively attenuates endothelial function in male mice via exosomes-mediated ROS production

Background

Substantial sex differences exist in atherosclerosis. Excessive reactive oxygen species (ROS) formation could lead to endothelial dysfunction which is critical to atherosclerosis development and progression. Helicobacter pylori (H. pylori) infection has been shown to attenuate endothelial function via exosomes-mediated ROS formation. We have demonstrated that H. pylori infection selectively increases atherosclerosis risk in males with unknown mechanism(s). The present study was to test the hypothesis that H. pylori infection impaired endothelial function selectively in male mice through exosome-mediated ROS formation.

Methods and results

Age-matched male and female C57BL/6 mice were infected with CagA+ H. pylori to investigate sex differences in H. pylori infection-induced endothelial dysfunction. H. pylori infection attenuated acetylcholine (ACh)-induced endothelium-dependent aortic relaxation without changing nitroglycerine-induced endothelium-independent relaxation in male but not female mice, associated with increased ROS formation in aorta compared with controls, which could be reversed by N-acetylcysteine treatment. Treatment of cultured mouse brain microvascular endothelial cells with exosomes from H. pylori infected male, not female, mice significantly increased intracellular ROS production and impaired endothelial function with decreased migration, tube formation, and proliferation, which could be prevented with N-acetylcysteine treatment.

Conclusions

H. pylori infection selectively impairs endothelial function in male mice due to exosome-mediated ROS formation.

Perigestational exposure of a combination of a high-fat diet and pesticide impacts the metabolic and microbiotic status of dams and pups; a preventive strategy based on prebiotics

PURPOSE

Metabolic changes during the perinatal period are known to promote obesity and type-2 diabetes in adulthood via perturbation of the microbiota. The risk factors for metabolic disorders include a high-fat diet (HFD) and exposure to pesticide residues. The objective of the present study was to evaluate the effects of perigestational exposure to a HFD and chlorpyrifos (CPF) on glycemia, lipid profiles, and microbial populations in Wistar dams and their female offspring. We also tested a preventive strategy based on treatment with the prebiotic inulin.

METHODS

From 4 months before gestation to the end of the lactation period, six groups of dams were exposed to either a standard diet, a HFD alone, CPF alone, a combination of a HFD and CPF, and/or inulin supplementation. All female offspring were fed a standard diet from weaning to adulthood. We measured the impacts of these exposures on glycemia, the lipid profile, and the microbiota (composition, metabolite production, and translocation into tissues).

RESULTS

HFD exposure and CPF + HFD co-exposure induced dysmetabolism and an imbalance in the gut flora in both the dams and the female offspring. Inulin mitigated the impact of exposure to a HFD alone but not that of CPF + HFD co-exposure.

CONCLUSION

Our results provide a better understanding of the complex interactions between environmental pollutants and diet in early life, including in the context of metabolic diseases.

Prebiotic inulin nanocoating for pancreatic islet surface engineering

Pancreatic islet surface engineering has been proposed as an "easy-to-adopt" approach to enhance post-transplantation islet engraftment for treatment against diabetes. Inulin is an FDA-approved dietary prebiotic with reported anti-diabetic, anti-inflammatory, anti-hypoxic and pro-angiogenic properties. We therefore assessed whether inulin would be a viable option for islet surface engineering. Inulin was oxidized to generate inulin-CHO, which would bind to the cell membrane via covalent bond formation between -CHO and -NH₂ across the islet cell membrane. In vitro assessments demonstrated enhanced islet viability and better glucose-induced insulin secretion from inulin-coated (5 mg mL^-1) islets, which was accompanied by enhanced revascularization, shown as significantly enhanced tube formation and branching of islet endothelial MS1 cells following co-culture with inulin-coated islets. Reduction of cytokine-induced cell death was also observed from inulin-coated islets following exposure to pro-inflammatory cytokine LPS. LPS-induced ROS production was significantly dampened by 44% in inulin-coated islets when compared to controls. RNA-seq analysis of inulin-coated and control islets identified expression alterations of genes involved in islet function, vascular formation and immune regulation, supporting the positive impact of inulin on islet preservation. In vivo examination using streptozotocin (STZ)-induced hyperglycemic mice further showed moderately better maintained plasma glucose levels in mice received transplantation of inulin-coated islets, attributable to ameliorated CD45⁺ immune cell infiltration and improved in vivo graft vascularization. We therefore propose islet surface engineering with inulin as safe and beneficial, and further assessment is required to verify its applicability in clinical islet transplantation.

6α-hydroxylated bile acids mediate TGR5 signalling to improve glucose metabolism upon dietary fiber supplementation in mice

OBJECTIVE

Dietary fibres are essential for maintaining microbial diversity and the gut microbiota can modulate host physiology by metabolising the fibres. Here, we investigated whether the soluble dietary fibre oligofructose improves host metabolism by modulating bacterial transformation of secondary bile acids in mice fed western-style diet.

DESIGN

To assess the impact of dietary fibre supplementation on bile acid transformation by gut bacteria, we fed conventional wild-type and TGR5 knockout mice western-style diet enriched or not with cellulose or oligofructose. In addition, we used germ-free mice and in vitro cultures to evaluate the activity of bacteria to transform bile acids in the caecal content of mice fed with western-style diet enriched with oligofructose. Finally, we treated wild-type and TGR5 knockout mice orally with hyodeoxycholic acid to assess its antidiabetic effects.

RESULTS

We show that oligofructose sustains the production of 6α-hydroxylated bile acids from primary bile acids by gut bacteria when fed western-style diet. Mechanistically, we demonstrated that the effects of oligofructose on 6α-hydroxylated bile acids were microbiota dependent and specifically required functional TGR5 signalling to reduce body weight gain and improve glucose metabolism. Furthermore, we show that the 6α-hydroxylated bile acid hyodeoxycholic acid stimulates TGR5 signalling, in vitro and in vivo, and increases GLP-1R activity to improve host glucose metabolism.

CONCLUSION

Modulation of the gut microbiota with oligofructose enriches bacteria involved in 6α-hydroxylated bile acid production and leads to TGR5-GLP1R axis activation to improve body weight and metabolism under western-style diet feeding in mice.

Microbiota: A potential orchestrator of antidiabetic therapy

The gut microbiota, as a 'new organ' of humans, has been identified to affect many biological processes, including immunity, inflammatory response, gut-brain neural circuits, and energy metabolism. Profound dysbiosis of the gut microbiome could change the metabolic pattern, aggravate systemic inflammation and insulin resistance, and exacerbate metabolic disturbance and the progression of type 2 diabetes (T2D). The aim of this review is to focus on the potential roles and functional mechanisms of gut microbiota in the antidiabetic therapy. In general, antidiabetic drugs (α-glucosidase inhibitor, biguanides, incretin-based agents, and traditional Chinese medicine) induce the alteration of microbial diversity and composition, and the levels of bacterial component and derived metabolites, such as lipopolysaccharide (LPS), short chain fatty acids (SCFAs), bile acids and indoles. The altered microbial metabolites are involved in the regulation of gut barrier, inflammation response, insulin resistance and glucose homeostasis. Furthermore, we summarize the new strategies for antidiabetic treatment based on microbial regulation, such as pro/prebiotics administration and fecal microbiota transplantation, and discuss the need for more basic and clinical researches to evaluate the feasibility and efficacy of the new therapies for diabetes.

Inulin increases the beneficial effects of rhubarb supplementation on high-fat high-sugar diet-induced metabolic disorders in mice: impact on energy expenditure, brown adipose tissue activity, and microbiota

Consumption of prebiotics and plant-based compounds have many beneficial health effects through modulation of gut microbiota composition and are considered as promising nutritional strategy for the treatment of metabolic diseases. In the present study, we assessed the separated and combined effects of inulin and rhubarb on diet-induced metabolic disease in mice. We showed that supplementation with both inulin and rhubarb abolished the total body and fat mass gain upon high-fat and high-sucrose diet (HFHS) as well as several obesity-associated metabolic disorders. These effects were associated with increased energy expenditure, lower whitening of the brown adipose tissue, higher mitochondria activity and increased expression of lipolytic markers in white adipose tissue. Despite modifications of intestinal gut microbiota and bile acid compositions by inulin or rhubarb alone, combination of both inulin and rhubarb had minor additional impact on these parameters. However, the combination of inulin and rhubarb increased the expression of several antimicrobial peptides and higher goblet cell numbers, thereby suggesting a reinforcement of the gut barrier. Together, these results suggest that the combination of inulin and rhubarb in mice potentiates beneficial effects of separated rhubarb and inulin on HFHS-related metabolic disease and could be considered as nutritional strategy for the prevention and treatment of obesity and related pathologies.

Role of Gut Microbiome in Atherosclerosis: Molecular and Therapeutic Aspects

Atherosclerosis is one of the most relevant and prevalent cardiovascular diseases of our time. It is one of the pathological entities that increases the morbidity and mortality index in the adult population. Pathophysiological connections have been observed between atherosclerosis and the gut microbiome (GM), represented by a group of microorganisms that are present in the gut. These microorganisms are vital for metabolic homeostasis in humans. Recently, direct and indirect mechanisms through which GM can affect the development of atherosclerosis have been studied. This has led to research into the possible modulation of GM and metabolites as a new target in the prevention and treatment of atherosclerosis. The goal of this review is to analyze the physiopathological mechanisms linking GM and atherosclerosis that have been described so far. We also aim to summarize the recent studies that propose GM as a potential target in atherosclerosis management.

Effects of neutral polysaccharide from Platycodon grandiflorum on high-fat diet-induced obesity via the regulation of gut microbiota and metabolites

The obesity epidemic has become a global problem with far-reaching health and economic impact. Despite the numerous therapeutic efficacies of Platycodon grandiflorum, its role in modulating obesity-related metabolic disorders has not been clarified. In this study, a purified neutral polysaccharide, PGNP, was obtained from Platycodon grandiflorum. Based on methylation and NMR analyses, PGNP was found to be composed of 2,1-β-D-Fruf residues ending with a (1→2)-bonded α-D-Glcp. The protective effects of PGNP on high-fat HFD-induced obesity were assessed. According to our results, PGNP effectively alleviated the signs of metabolic syndrome, as demonstrated by reductions in body weight, hepatic steatosis, lipid profile, inflammatory response, and insulin resistance in obese mice. Under PGNP treatment, intestinal histomorphology and the tight junction protein, ZO-1, were well maintained. To elucidate the underlying mechanism, 16S rRNA gene sequencing and LC-MS were employed to assess the positive influence of PGNP on the gut microbiota and metabolites. PGNP effectively increased species diversity of gut microbiota and reversed the HFD-induced imbalance in the gut microbiota by decreasing the Firmicutes to Bacteroidetes ratio. The abundance of Bacteroides and Blautia were increased after PGNP treatment, while the relative abundance of Rikenella, Helicobacter were reduced. Furthermore, PGNP notably influenced the levels of microbial metabolites, including the increased levels of cholic and gamma-linolenic acid. Overall, PGNP might be a potential supplement for the regulation of gut microbiota and metabolites, further affecting obesity.

Stable isotope tracing in vivo reveals a metabolic bridge linking the microbiota to host histone acetylation

The gut microbiota influences acetylation on host histones by fermenting dietary fiber into butyrate. Although butyrate could promote histone acetylation by inhibiting histone deacetylases, it may also undergo oxidation to acetyl-coenzyme A (CoA), a necessary cofactor for histone acetyltransferases. Here, we find that epithelial cells from germ-free mice harbor a loss of histone H4 acetylation across the genome except at promoter regions. Using stable isotope tracing in vivo with 13C-labeled fiber, we demonstrate that the microbiota supplies carbon for histone acetylation. Subsequent metabolomic profiling revealed hundreds of labeled molecules and supported a microbial contribution to host fatty acid metabolism, which declined in response to colitis and correlated with reduced expression of genes involved in fatty acid oxidation. These results illuminate the flow of carbon from the diet to the host via the microbiota, disruptions to which may affect energy homeostasis in the distal gut and contribute to the development of colitis.

Microbial treatment of alcoholic liver disease: A systematic review and meta-analysis

Background and aims

Alcoholic liver disease (ALD) is characterized by impaired liver function due to chronic alcohol consumption, even fatal in severe cases. We performed a meta-analysis to determine whether microbial agents have therapeutic potential for ALD and elucidate the underlying mechanisms.

Methods and results

Forty-one studies were eligible for this meta-analysis after searching the PubMed, Cochrane, and Embase databases. The combined analysis showed that microbial therapy significantly decreased hepatic enzymatic parameters, including alanine transaminase [standardized mean difference (SMD): -2.70, 95% confidence interval (CI): -3.33 to -2.07], aspartate aminotransferase (SMD: -3.37, 95% CI: -4.25 to -2.49), γ-glutamyl transpeptidase (SMD: -2.07, 95% CI: -3.01 to -1.12), and alkaline phosphatase (SMD: -2.12, 95% CI: -3.32 to -0.92). Microbial agents endotoxin to enter the portal circulation and increasing reduced total cholesterol (SMD = -2.75, 95%CI -4.03 to -1.46) and triglycerides (SMD = -2.64, 95% CI: -3.22 to -2.06). Microbial agents increased amounts of the beneficial flora Lactobacillus (SMD: 4.40, 95% CI: 0.97-7.84) and Bifidobacteria (SMD: 3.84, 95% CI: 0.22-7.45), Bacteroidetes (SMD: 2.51, 95% CI: 0.29-4.72) and decreased harmful Proteobacteria (SMD: -4.18, 95% CI: -6.60 to -1.77), protecting the integrity of the intestinal epithelium and relieving endotoxin (SMD: -2.70, 95% CI: -3.52 to -2.17) into the portal vein, thereby reducing the production of inflammatory factors such as tumor necrosis factor-α (SMD: -3.35, 95% CI: -4.31 to -2.38), interleukin-6 (SMD: -4.28, 95% CI: -6.13 to -2.43), and interleukin-1β (SMD: -4.28, 95% CI: -6.37 to -2.19). Oxidative stress was also relieved, as evidenced by decreased malondialdehyde levels (SMD: -4.70, 95% CI: -6.21 to -3.20). Superoxide dismutase (SMD: 2.65, 95% CI: 2.16-3.15) and glutathione levels (SMD: 3.80, 95% CI: 0.95-6.66) were elevated.

Conclusion

Microbial agents can reverse dysbiosis in ALD, thus significantly interfering with lipid metabolism, relieving inflammatory response and inhibiting oxidative stress to improve liver function.

Gene and Protein Accumulation Changes Evoked in Porcine Aorta in Response to Feeding with Two Various Fructan Sources

In this study, two different ITFs sources were incorporated into a cereal-based diet to evaluate possible aortic protein and gene changes in nursery pigs. The animals were fed two different experimental diets from the 10th day of life, supplemented with either 4% of dried chicory root (CR) or with 2% of native inulin (IN). After a 40-day dietary intervention trial, pigs were sacrificed at day 50 and the aortas were harvested. Our data indicate that dietary ITFs have the potential to influence several structural and physiological changes that are reflected both in the mRNA and protein levels in porcine aorta. In contrast to our hypothesis, we could not show any beneficial effects of a CR diet on vascular functions. The direction of changes of several proteins and genes may indicate disrupted ECM turnover (COL6A1 and COL6A2, MMP2, TIMP3, EFEMP1), increased inflammation and lipid accumulation (FFAR2), as well as decreased activity of endothelial nitric oxide synthase (TXNDC5, ORM1). On the other hand, the IN diet may counteract a highly pro-oxidant environment through the endothelin-NO axis (CALR, TCP1, HSP8, PDIA3, RCN2), fibrinolytic activity (ANXA2), anti-atherogenic (CAVIN-1) and anti-calcification (LMNA) properties, thus contributing to the maintenance of vascular homeostasis.

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.

Secondary bile acids mediate high-fat diet-induced upregulation of R-spondin 3 and intestinal epithelial proliferation

A high-fat diet (HFD) contributes to the increased incidence of colorectal cancer, but the mechanisms are unclear. We found that R-spondin 3 (Rspo3), a ligand for leucine-rich, repeat-containing GPCR 4 and 5 (LGR4 and LGR5), was the main subtype of R-spondins and was produced by myofibroblasts beneath the crypts in the intestine. HFD upregulated colonic Rspo3, LGR4, LGR5, and β-catenin gene expression in specific pathogen-free rodents, but not in germ-free mice, and the upregulations were prevented by the bile acid (BA) binder cholestyramine or antibiotic treatment, indicating mediation by both BA and gut microbiota. Cholestyramine or antibiotic treatments prevented HFD-induced enrichment of members of the Lachnospiraceae and Rumincoccaceae, which can transform primary BA into secondary BA. Oral administration of deoxycholic acid (DCA), or inoculation of a combination of the BA deconjugator Lactobacillus plantarum and 7α-dehydroxylase-containing Clostridium scindens with an HFD to germ-free mice increased serum DCA and colonic Rspo3 mRNA levels, indicating that formation of secondary BA by gut microbiota is responsible for HFD-induced upregulation of Rspo3. In primary myofibroblasts, DCA increased Rspo3 mRNA via TGR5. Finally, we showed that cholestyramine or conditional deletion of Rspo3 prevented HFD- or DCA-induced intestinal proliferation. We conclude that secondary BA is responsible for HFD-induced upregulation of Rspo3, which, in turn, mediates HFD-induced intestinal epithelial proliferation.

Inulin accelerates weight loss in obese mice by regulating gut microbiota and serum metabolites

Several studies indicated that the gut microbiota might participate in the beneficial effect of inulin on obesity. However, the mechanisms involved were still largely unknown. Sixteen high-fat diets (HFDs)-induced obese C57BL/6 mice were converted to a normal diet and then randomized into two groups, OND (obese mice + normal diet) group gavage-fed for 10 weeks with normal saline and ONDI (obese mice + normal diet + inulin) group with inulin at 10 g/kg/day. The body weight of HFD-induced obese mice showed different degrees of decrease in both groups. However, the ONDI group lost more weight and returned to normal earlier. Compared to the OND group, inulin supplementation significantly shifted the composition and structure of gut microbiota, such as higher α diversity. The β diversity analysis also confirmed the changes in gut microbiota composition between groups. At the genus level, the abundance of Alistipes was considerably increased, and it was significantly correlated with inulin supplementation (r = 0.72, P = 0.002). Serum metabolite levels were distinctly altered after inulin supplementation, and 143 metabolites were significantly altered in the ONDI group. Among them, indole-3-acrylic acid level increased more than 500-fold compared to the OND group. It was also strongly positive correlation with Alistipes (r = 0.72, P = 0.002) and inulin supplementation (r = 0.99, P = 9.2e−13) and negatively correlated with obesity (r = −0.72, P = 0.002). In conclusion, inulin supplementation could accelerate body weight loss in obese mice by increasing Alistipes and indole-3-acrylic acid level.

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

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

Inulin intake and the incidence of cardiometabolic diseases: a prospective cohort study

Inulin is a prebiotic and has beneficial effects on health, such as improving the immune function, lipid profile, and gut microbiota. Some previous studies have assessed the effects of inulin supplementation on cardiometabolic diseases, but the relationship between dietary inulin and these diseases has not been investigated yet. Thus, this survey was designed to assess the potential association between the dietary intake of inulin and the incidence of cardiometabolic diseases, including cardiovascular disease (CVD), hypertension (HTN), chronic kidney disease (CKD), and type 2 diabetes (T2D) among adults. The present prospective cohort study was conducted on participants in the third wave of the Tehran Lipid and Glucose Study (2006-2008) and was followed up until March 2018. The dietary intake of inulin was estimated using a special database that reports values of inulin and oligofructose in grams per 100 g of each food. Cox proportional hazards regression showed that higher consumption of inulin was associated with a lower risk of HTN (HR: 0.79, 95% CI: 0.63 to 0.99) and T2D (HR: 0.94, 95% CI: 0.89 to 1.00). We found no relationship between higher consumption of dietary inulin and the incidence of CKD and CVD in our population. According to our results, it seems inulin from foods had a preventive effect against HTN and T2D, which are major risk factors for cardiovascular and renal events. However, more investigations are warranted.

Effects of inulin-type fructans with different degrees of polymerization on inflammation, oxidative stress and endothelial dysfunction in women with polycystic ovary syndrome: A randomized, double-blind, placebo-controlled trial

OBJECTIVE

Polycystic ovary syndrome (PCOS) is associated with several cardiovascular risk factors. Prebiotics were proposed to beneficially affect risk factors associated with metabolic disorders. The aim of this study was to investigate and compare the effects of inulin-type fructans (ITFs), as well-studied prebiotics, with different degrees of polymerization, on markers of inflammation, oxidative stress and endothelial dysfunction in PCOS patients.

DESIGN

A randomized, double-blind, placebo-controlled trial.

PATIENTS

Seventy-five PCOS women were randomly assigned to receive 10 g/day of either high-performance inulin (HPI) or oligofructose-enriched inulin (OEI) or placebo for 12 weeks.

MEASUREMENTS

Biochemical indices and blood pressure levelswere assessed before and after the intervention.

RESULTS

In the intent-to-treat analysis, high-sensitive C-reactive protein (hs-CRP) decreased in HPI and OEI groups, over the 12 weeks, and the changes were significant in the HPI group, compared to placebo (changes from baseline in the HPI group: -0.11 vs. placebo group: 0.004 mg/L [conversion factor to SI units (nmol/L): 9/5238]; p = .007). Serum levels of nitric oxide (NO) increased, and endothelin-1 and total oxidant status decreased in HPI and OEI groups, at the end of the trial; however, these changes were not significantly compared to placebo (p = .07, .36 and .22, respectively). No differences in systolic and diastolic blood pressure were found. Per-protocol analysis (n = 68) yielded consistent results for all endpoints, with the exception that the significant effect of ITFs on serum hs-CRP levels in the unadjusted ITT analysis became nonsignificant in the per-protocol analysis (p = .06).

CONCLUSION

A 12-week supplementation with long-chain ITFs had favourable effects on inflammatory status among PCOS patients.

Bile acid metabolism and signaling, the microbiota, and metabolic disease

The diversity, composition, and function of the bacterial community inhabiting the human gastrointestinal tract contributes to host health through its role in producing energy or signaling molecules that regulate metabolic and immunologic functions. Bile acids are potent metabolic and immune signaling molecules synthesized from cholesterol in the liver and then transported to the intestine where they can undergo metabolism by gut bacteria. The combination of host- and microbiota-derived enzymatic activities contribute to the composition of the bile acid pool and thus there can be great diversity in bile acid composition that depends in part on the differences in the gut bacteria species. Bile acids can profoundly impact host metabolic and immunological functions by activating different bile acid receptors to regulate signaling pathways that control a broad range of complex symbiotic metabolic networks, including glucose, lipid, steroid and xenobiotic metabolism, and modulation of energy homeostasis. Disruption of bile acid signaling due to perturbation of the gut microbiota or dysregulation of the gut microbiota-host interaction is associated with the pathogenesis and progression of metabolic disorders. The metabolic and immunological roles of bile acids in human health have led to novel therapeutic approaches to manipulate the bile acid pool size, composition, and function by targeting one or multiple components of the microbiota-bile acid-bile acid receptor axis.

Gut Microbiota Modulation as a Novel Therapeutic Strategy in Cardiometabolic Diseases

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

Evaluation of Full-Length Versus V4-Region 16S rRNA Sequencing for Phylogenetic Analysis of Mouse Intestinal Microbiota After a Dietary Intervention

The composition of microbial communities is commonly determined by sequence analyses of one of the variable (V) regions in the bacterial 16S rRNA gene. We aimed to assess whether sequencing the full-length versus the V4 region of the 16S rRNA gene affected the results and interpretation of an experiment. To test this, mice were fed a diet without and with the prebiotic inulin and from cecum samples, two primary data sets were generated: (1) a 16S rRNA full-length data set generated by the PacBio platform; (2) a 16S rRNA V4 region data set generated by the Illumina MiSeq platform. A third derived data set was generated by in silico extracting the 16S rRNA V4 region data from the 16S rRNA full-length PacBio data set. Analyses of the primary and derived 16S rRNA V4 region data indicated similar bacterial abundances, and α- and β-diversity. However, comparison of the 16S rRNA full-length data with the primary and derived 16S rRNA V4 region data revealed differences in relative bacterial abundances, and α- and β-diversity. We conclude that the sequence length of 16S rRNA gene and not the sequence analysis platform affected the results and may lead to different interpretations of the effect of an intervention that affects the microbiota.

Inulin-type fructans change the gut microbiota and prevent the development of diabetic nephropathy

Diabetic nephropathy (DN) is the most common cause of end-stage renal disease, and few treatment options that prevent the progressive loss of renal function are available. Studies have shown that dietary fiber intake improves kidney diseases and metabolism-related diseases, most likely through short-chain fatty acids (SCFAs). The present study aimed to examine the protective effects of inulin-type fructans (ITFs) on DN through 16 S rRNA gene sequencing, gas chromatographymass spectrometry (GCMS) analysis and fecal microbiota transplantation (FMT). The results showed that ITFs supplementation protected against kidney damage in db/db mice and regulated the composition of the gut microbiota. Antibiotic treatment and FMT experiments further demonstrated a key role of the gut microbiota in mediating the beneficial effects of ITFs. The ITFs treatment-induced changes in the gut microbiota led to an enrichment of SCFA-producing bacteria, especially the genera Akkermansia and Candidatus Saccharimonas, which increased the fecal and serum acetate concentrations. Subsequently, acetate supplementation improved glomerular damage and renal fibrosis by attenuating mitochondrial dysfunction and reducing toxic glucose metabolite levels. In conclusion, ITFs play a renoprotective role by modulating the gut microbiota and increasing acetate production. Furthermore, acetate mediates renal protection by regulating glucose metabolism, decreasing glycotoxic product levels and improving mitochondrial function.

Effect of daily co-exposure to inulin and chlorpyrifos on selected microbiota endpoints in the SHIME® model

The intestinal microbiota has a key role in human health via the interaction with the somatic and immune cells in the digestive tract environment. Food, through matrix effect, nutrient and non-nutrient molecules, is a key regulator of microbiota diversity. As a food contaminant, the pesticide chlorpyrifos (CPF) has an effect on the composition of the intestinal microbiota and induces perturbation of microbiota. Prebiotics (and notably inulin) are known for their ability to promote an equilibrium of the microbiota that favours saccharolytic bacteria. The SHIME® dynamic in vitro model of the human intestine was exposed to CPF and inulin concomitantly for 30 days, in order to assess variations in both the bacterial populations and their metabolites. Various analyses of the microbiota (notably temporal temperature gradient gel electrophoresis) revealed a protective effect of the prebiotic through inhibition of the enterobacterial (E. coli) population. Bifidobacteria were only temporarily inhibited at D15 and recovered at D30. Although other potentially beneficial populations (lactobacilli) were not greatly modified, their activity and that of the saccharolytic bacteria in general were highlighted by an increase in levels of short-chain fatty acids and more specifically butyrate. Given the known role of host-microbiota communication, CPF's impact on the body's homeostasis remains to be determined.