Prebiotic intervention with HAMSAB in untreated essential hypertensive patients assessed in a phase II randomized trial

Faecal metaproteomics analysis reveals a high cardiovascular risk profile across healthy individuals and heart failure patients

The gut microbiota is a crucial link between diet and cardiovascular disease (CVD). Using fecal metaproteomics, a method that concurrently captures human gut and microbiome proteins, we determined the crosstalk between gut microbiome, diet, gut health, and CVD. Traditional CVD risk factors (age, BMI, sex, blood pressure) explained < 10% of the proteome variance. However, unsupervised human protein-based clustering analysis revealed two distinct CVD risk clusters (low-risk and high-risk) with different blood pressure (by 9 mmHg) and sex-dependent dietary potassium and fiber intake. In the human proteome, the low-risk group had lower angiotensin-converting enzymes, inflammatory proteins associated with neutrophil extracellular trap formation and auto-immune diseases. In the microbial proteome, the low-risk group had higher expression of phosphate acetyltransferase that produces SCFAs, particularly in fiber-fermenting bacteria. This model identified severity across phenotypes in heart failure patients and long-term risk of cardiovascular events in a large population-based cohort. These findings underscore multifactorial gut-to-host mechanisms that may underlie risk factors for CVD.

Gut-Heart Axis: The Role of Gut Microbiota and Metabolites in Heart Failure

Heart failure is a global health issue with significant mortality and morbidity. There is increasing evidence that alterations in the gastrointestinal microbiome, gut epithelial permeability, and gastrointestinal disorders contribute to heart failure progression through various pathways, including systemic inflammation, metabolic dysregulation, and modulation of cardiac function. Moreover, several medications used to treat heart failure directly impact the microbiome. The relationship between the gastrointestinal tract and the heart is bidirectional, termed the gut-heart axis. It is increasingly understood that diet-derived microbial metabolites are key mechanistic drivers of the gut-heart axis. This includes, for example, trimethylamine N-oxide and short-chain fatty acids. This review discusses current insights into the interplay between heart failure, its associated risk factors, and the gut microbiome, focusing on key metabolic pathways, the role of dietary interventions, and the potential for gut-targeted therapies. Understanding these complex interactions could pave the way for novel strategies to mitigate heart failure progression and improve patient outcomes.

The Gut Microbiome as a Key Determinant of the Heritability of Body Mass Index

The pathogenesis of obesity is complex and incompletely understood, with an underlying interplay between our genetic architecture and obesogenic environment. The public understanding of the development of obesity is shrouded in myths with widespread societal misconceptions. Body Mass Index (BMI) is a highly heritable trait. However, despite reports from recent genome-wide association studies, only a small proportion of the overall heritability of BMI is known to be lurking within the human genome. Other non-genetic heritable traits may contribute to BMI. The gut microbiome is an excellent candidate, implicating complex interlinks with hypothalamic control of appetite and metabolism via entero-endocrine, autonomic, and neuro-humeral pathways. The neonatal gut microbiome derived from the mother via transgenerational transmission (vaginal delivery and breastfeeding) tends to have a permanence within the gut. Conversely, non-maternally derived gut microbiota manifest mutability that responds to changes in lifestyle and diet. We should all strive to optimize our lifestyles and ensure a diet that is replete with varied and unprocessed plant-based foods to establish and nurture a healthy gut microbiome. Women of reproductive age should optimize their gut microbiome, particularly pre-conception, ante- and postnatally to enable the establishment of a healthy neonatal gut microbiome in their offspring. Finally, we should redouble our efforts to educate the populace on the pathogenesis of obesity, and the role of heritable (but modifiable) factors such as the gut microbiome. Such renewed understanding and insights would help to promote the widespread adoption of healthy lifestyles and diets, and facilitate a transition from our current dispassionate and stigmatized societal approach towards people living with obesity towards one that is epitomized by understanding, support, and compassion.

The Influence of the Sympathetic Nervous System on Cardiometabolic Health in Response to Weight Gain or Weight Loss

Alterations in sympathetic nervous activity are evident in response to changes in body weight. Sympathetic nervous activity and sympathetic responses to weight change are regionalized, with alterations in end organ function dependent on the changes occurring in the brain regulatory pathways invoked and in the effector organs engaged. The obesity-induced activation of the sympathetic nervous system likely contributes to the initiation and worsening of cardiometabolic risk factors, including elevated blood pressure, cardiac dysfunction, dyslipidaemia, increased fasting blood glucose, insulin resistance, and non-alcoholic steatohepatitis. Unintended weight loss, as occurs in cachexia, is driven, at least in part, by the activation of sympathetic nervous-stimulated thermogenesis. The complexity of sympathetic nervous regulation renders the use of global measures of sympathetic activity problematic and the development of targeted therapies difficult, but these are not without promise or precedent. Knowledge of the central and peripheral pathways involved in sympathetic nervous regulation has opened up opportunities for pharmacological, surgical, and device-based approaches to mitigating the burden of disease development and progression. In this narrative review, we elaborate on sympathetic activity in response to changes in body weight, the brain pathways involved, and the cardiovascular and metabolic risks associated with perturbations in regional sympathetic activity.

"Gut Microbiota as a Therapeutic Target for Hypertension: Challenges and Insights for Future Clinical Applications" "Gut Microbiota and Hypertension Therapy"

PURPOSE OF REVIEW

Systemic hypertension is a major risk factor for cardiovascular disease and remains challenging to manage despite the widespread use of antihypertensive medications and lifestyle modifications. This review explores the role of gut microbiota in hypertension development and regulation, highlighting key mechanisms such as inflammation, gut-brain axis modulation, and bioactive metabolite production. We also assess the potential of microbiota-targeted therapies for hypertension management.

RECENT FINDINGS

Emerging evidence indicates that microbial dysbiosis, high-salt diets, and gut-derived metabolites such as short-chain fatty acids (SCFAs) and bile acids significantly influence blood pressure regulation. Preclinical and early clinical studies suggest that interventions targeting gut microbiota, including probiotics, prebiotics, synbiotics, fecal microbiota transplantation (FMT), and dietary modifications, may help modulate hypertension. However, variability in gut microbiota composition among individuals and limited human trial data pose challenges to translating these findings into clinical practice. While microbiota-based therapies show promise for hypertension management, further research is needed to establish their efficacy and long-term effects. Large-scale, standardized clinical trials are crucial for understanding the therapeutic potential and limitations of gut microbiota interventions. A deeper understanding of the gut-hypertension axis could lead to novel, personalized treatment strategies for hypertension.

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.

SCFA biotherapy delays diabetes in humanized gnotobiotic mice by remodeling mucosal homeostasis and metabolome

Type 1 diabetes (T1D) is linked to an altered gut microbiota characterized by reduced short-chain fatty acid (SCFA) production. Oral delivery of a SCFA-yielding biotherapy in adults with T1D was followed by increased SCFAs, altered gut microbiota and immunoregulation, as well as delaying diabetes in preclinical models. Here, we show that SCFA-biotherapy in humans is accompanied by remodeling of the gut proteome and mucosal immune homeostasis. Metabolomics showed arginine, glutamate, nucleotide and tryptophan metabolism were enriched following the SCFA-biotherapy, and found metabolites that correlated with glycemic control. Fecal microbiota transfer demonstrated that the microbiota of SCFA-responders delayed diabetes progression in humanized gnotobiotic mice. The protected mice increased similar metabolite pathways to the humans including producing aryl-hydrocarbon receptor ligands and reducing inflammatory mucosal immunity and increasing IgA production in the gut. These data demonstrate that a potent SCFA immunomodulator promotes multiple beneficial pathways and supports targeting the microbiota as an approach against T1D. Trial registration: Australia New Zealand Clinical Trials Registry ACTRN12618001391268.

Steric Inhibition by Butyryl Groups on Gut Microbial Amylases Significantly Impacts In Vitro Fecal Fermentation of Butyrylated Starch

Colonic starch fermentation requires the assistance of gut microbial amylases (GMAs). However, it remains unknown whether chemically substituted butyryl groups induce a steric inhibitory effect on GMAs analogous to that observed with pancreatic amylase during the intestinal digestion of butyrylated starch. In this study, we investigated the in vitro fermentation and enzymatic hydrolysis performance of three types of butyrylated starch. The results showed that the esterolysis of butyryl groups was a rate-limiting process, and the fermentation of butyrylated starch was partially inhibited by steric inhibition of the butyryl groups on GMAs. X-ray photoelectron spectroscopy (XPS) results further confirmed the negative correlation between the fermentation rate of starch and the relative content of butyryl groups accessible to the gut microbiota. Moreover, analyses of the enzymatic characteristics and the resulting hydrolysate composition demonstrated that a relatively high multiple attack degree (MAD) made GMAs more susceptible to steric inhibition by butyryl groups, thus producing more malto-oligosaccharides, which are preferred by butyrate-producing bacteria. These findings provide important insights into the fermentation behavior of butyrylated starch from the perspective of interactions between microbial amylases and starch.

Gut Microbiota Alterations in Patients With Kawasaki Disease

The intestinal microbiota influences many host biological processes, including metabolism, intestinal barrier functions, and immune responses in the gut and distant organs. Alterations in its composition have been associated with the development of inflammatory disorders and cardiovascular diseases, including Kawasaki disease (KD). KD is an acute pediatric vasculitis of unknown etiology and the leading cause of acquired heart disease in children in the United States. The presence of gastrointestinal symptoms in the acute phase of KD has been associated with an increased risk of treatment resistance and the development of coronary artery aneurysms. Studies report alterations in fecal bacterial communities of patients with KD, characterized by the blooming of pathogenic bacteria and decreased relative abundance of short-chain fatty acid-producing bacteria. However, causality and functionality cannot be established from these observational patient cohorts of KD. This highlights the need for more advanced and rigorous studies to establish causality and functionality in both experimental models of KD vasculitis and patient cohorts. Here, we review the evidence linking an altered gut microbiota composition to the development of KD, assess the potential mechanisms involved in this process, and discuss the potential therapeutic value of these observations.

The influence of microplastics on hypertension-associated cardiovascular injury via the modulation of gut microbiota

Microplastics (MPs) have been found to interfere with the gut microbiota and compromise the integrity of the gut barrier. Excessive exposure to MPs markedly elevates the risk of cardiovascular disease, yet their influence on hypertension remains elusive, calling for investigation into their potential impacts on blood pressure (BP) regulation. In the present study, an increase in the concentration of MPs was observed in the fecal samples of individuals suffering from hypertension, as compared to the controls. Oral administration of MPs led to obvious increases in systolic, diastolic and mean BP levels in mice. MPs were associated with promoting myocardial hypertrophy, fibrosis, and cardiac remodeling through alterations in gut microbial composition, such as Prevotella and Coprobacillus, or fecal metabolites Betaine and Glycyrrhetinic acid. The hypertensive damage mediated by MPs was significantly mitigated by the high-fiber diet or antibiotics that targeted the gut microbiota. Notablely, fecal microbiota transplantation from mice treated with MPs led to an increase in systolic BP levels and the development of cardiac dysfunction. Our findings offer valuable insights into the complex interplay between MPs and the gut microbiome in the context of hypertension, and suggest potential strategies for reducing the vascular and cardiac injury caused by MPs.

Microbiome-Based Therapeutics for Salt-Sensitive Hypertension: A Scoping Review

The purpose of this scoping review was to provide a comprehensive understanding of the current knowledge concerning the gut microbiome and SCFAs as emerging treatments for salt-sensitive hypertension. Relevant animal and human studies were identified via PubMed through August 2024. Twenty-four human (n = 9) and animal (n = 15) trials were included. Most human studies were observational (n = 6), aiming to compare gut microbiota differences between hypertensive and normotensive individuals. Three human studies evaluated microbiome-based interventions either via a sodium-restricted diet (n = 2) or prebiotic supplementation (n = 1). Fifteen animal trials involving either mice or rats were identified, all of which were interventional. These included dietary changes (n = 9), probiotic treatments (n = 1), postbiotic primarily bacterial metabolites (n = 4), and live biotherapeutic products (n = 4). All interventions were effective in decreasing blood pressure. Microbiome-based therapies as biologic modifiers for salt-sensitive hypertension are emerging. Substantial knowledge gaps remain, warranting further research to fully explore this promising therapeutic avenue.

Butyrate increases cardiac output and causes vasorelaxation in a healthy porcine model

BACKGROUND

Butyrate, a short-chain fatty acid, has shown potential to improve left ventricular (LV) function and induce vasorelaxation in rodents. Butyrate may either be produced by the microbiome in the colon, be ingested or administered intravenously. This study aimed to evaluate effects of butyrate on cardiac output (CO) and associated hemodynamic variables in a porcine model.

METHODS

In a randomized, blinded crossover study, ten healthy 60-kg pigs were given three hour infusions of 600 mM butyrate and equimolar sodium chloride (control). CO was measured by thermodilution via a pulmonary artery catheter. LV contractility was assessed using pressure-volume admittance catheterization. Additionally, isolated porcine coronary arteries were exposed to butyrate in a wire myograph to evaluate vasorelaxation.

RESULTS

Butyrate infusion increased plasma butyrate concentration to 0.53 mM (95 % confidence interval (CI): 0.49 to 0.58 mM, P < 0.58 mM, P < 0.001) and CO by 1.6 L/min (95 % CI: 1.0 to 2.1 L/min, P < 0.001) compared with the control. Heart rate, LV ejection fraction, cardiac efficiency and dP/dtmax rose, while systemic vascular resistance, arterial elastance, mean arterial pressure and LV end-systolic volume decreased. Load-independent LV contractility and stroke volume did not significantly differ. In the myograph, porcine coronary arteries relaxed in response to butyrate in a concentration-dependent manner.

CONCLUSION

Butyrate increases cardiac output and lowers vascular resistance in a large animal model, through increased HR and systemic vasorelaxation. Load-independent LV contractility was not significantly altered. We observed indices of increased end-organ perfusion. These potentially beneficial cardiovascular properties of butyrate should be further studied.

Gut Microbiota Metabolites Sensed by Host GPR41/43 Protect Against Hypertension

BACKGROUND

Fermentation of dietary fiber by the gut microbiota leads to the production of metabolites called short-chain fatty acids, which lower blood pressure and exert cardioprotective effects. Short-chain fatty acids activate host signaling responses via the functionally redundant receptors GPR41 (G-protein-coupled receptor 41) and GPR43 (G-protein-coupled receptor 43), which are highly expressed by immune cells. Whether and how these receptors protect against hypertension or mediate the cardioprotective effects of dietary fiber remains unknown.

METHODS

Cardiovascular phenotype was assessed in untreated and Ang II (angiotensin II) treated hypertensive wild-type and GPR41/43 knockout (KO) double knockout male mice fed diets with different levels of fiber content. Some mice received TLR4 (toll-like receptor 4)-antagonist treatment and bone marrow chimeras. SNPs (single-nucleotide polymorphisms) associated with GPR41 and GPR43 expression were assessed in UK Biobank participants.

RESULTS

Untreated GPR41/43KO mice had unaltered blood pressure but had greater cardiac and renal collagen deposition with higher macrophage numbers in the kidney compared with wild-type mice. Ang II-treated GPR41/43KO mice showed higher systolic blood pressure, cardiorenal weights and collagen deposition, and increased gut permeability, which allows the translocation of gastrointestinal bacterial components such as lipopolysaccharides into the circulation. The use of an antagonist to the lipopolysaccharide receptor, TLR4, a potent proinflammatory signaling molecule, restored the cardiovascular phenotype in GPR41/43KO mice. The lack of GPR41/43 expression in the immune compartment was sufficient to lead to a worsened hypertensive phenotype. We also demonstrate that GPR41/43 is, at least partially, responsible for the blood pressure-lowering and cardioprotective effects of a high-fiber diet. Finally, using the UK Biobank, we provide translational evidence that variants associated with lower expression of both GPR41 and GPR43 are more prevalent in participants with hypertension.

CONCLUSIONS

Our findings highlight that lack of short-chain fatty acid-receptor signaling via both GPR41 and GPR43 increases risk of high blood pressure, suggesting treatments that target these receptors could be a novel strategy to prevent or treat hypertension.

Walnut peptide relieves hypertension and associated kidney and heart injury by regulating the renin-angiotensin-aldosterone system and intestinal microbiota

BACKGROUND

Hypertension is a chronic disease with high morbidity and mortality. Previously, we screened a walnut meal peptide FDWLR (PEP) with significant angiotensin-converting enzyme inhibitory activity. The present study further investigated the anti-hypertensive effects of PEP in vivo using spontaneously hypertensive rats.

RESULTS

The results indicated that PEP reduced blood pressure and the indices in the renin-angiotensin-aldosterone system (RAAS) including angiotensin-converting enzyme (ACE) (decreased by 15.36%), angiotensin II (Ang II) (decreased by 31.56%), angiotensinogen (AGT) (decreased by 58.84%) and aldosterone (ALD) (decreased by 18.27%), whereas NO levels increased by 54.96%. The pathological analysis showed that PEP relieved cardiac and renal damage. PEP also alleviated oxidative stress, inflammation and fibrosis in the heart and kidney. Mechanistically, PEP mitigated cardiac and renal damage by simultaneously regulating ACE-Ang II-AT1R and the ACE2-Ang (1-7)-MAS axis. Additionally, PEP increased the levels of short chain fatty acids by 224.16% and improved gut microbiota by increasing the abundance of Prevotella, Phascolarctobacterium, Clostridium_sensu_stricto and Bifidobacterium, at the same time as decreasing Bacteroides and Alistipes abundances.

CONCLUSION

This study indicated that PEP prevented hypertension and associated heart and kidney damage by modulating the RAAS system and gut microbiota, which is valuable in guiding future development and optimal utilization of walnut meal. © 2024 Society of Chemical Industry.

Sex differences in gut microbiota, hypertension, and cardiovascular risk

The intricate ecosystem of the gut microbiome exhibits sex-specific differences, influencing the susceptibility to cardiovascular diseases (CVD). Imbalance within the gut microbiome compromises the gut barrier, activates inflammatory pathways, and alters the production of metabolites, all of which initiate chronic diseases including CVD. In particular, the interplay between lifestyle choices, hormonal changes, and metabolic byproducts uniquely affects sex-specific gut microbiomes, potentially shaping the risk profiles for hypertension and CVD differently in men and women. Understanding the gut microbiome's role in CVD risk offers informative reasoning behind the importance of developing tailored preventative strategies based on sex-specific differences in CVD risk. Furthermore, insight into the differential impact of social determinants and biological factors on CVD susceptibility emphasizes the necessity for more nuanced approaches. This review also outlines specific dietary interventions that may enhance gut microbiome health, offering a glimpse into potential therapeutic avenues for reducing CVD risk that require greater awareness. Imbalance in natural gut microbiomes may explain etiologies of chronic diseases; we advocate for future application to alter the gut microbiome as possible treatment of the aforementioned diseases. This review mentions the idea of altering the gut microbiome through interventions such as fecal microbiota transplantation (FMT), a major application of microbiome-based therapy that is first-line for Clostridium difficile infections and patient-specific probiotics highlights more innovative approaches to hypertension and CVD prevention. Through increased analysis of gut microbiota compositions along with patient-centric probiotics and microbiome transfers, this review advocates for future preventative strategies for hypertension.

IUPHAR themed review: The gut microbiome in schizophrenia

Gut microbial dysbiosis or altered gut microbial consortium, in schizophrenia suggests a pathogenic role through the gut-brain axis, influencing neuroinflammatory and neurotransmitter pathways critical to psychotic, affective, and cognitive symptoms. Paradoxically, conventional psychotropic interventions may exacerbate this dysbiosis, with antipsychotics, particularly olanzapine, demonstrating profound effects on microbial architecture through disruption of bacterial phyla ratios, diminished taxonomic diversity, and attenuated short-chain fatty acid synthesis. To address these challenges, novel therapeutic strategies targeting the gut microbiome, encompassing probiotic supplementation, prebiotic compounds, faecal microbiota transplantation, and rationalised co-pharmacotherapy, show promise in attenuating antipsychotic-induced metabolic disruptions while enhancing therapeutic efficacy. Harnessing such insights, precision medicine approaches promise to transform antipsychotic prescribing practices by identifying patients at risk of metabolic side effects based on their microbial profiles. This IUPHAR review collates the current literature landscape of the gut-brain axis and its intricate relationship with schizophrenia while advocating for integrating microbiome assessments and therapeutic management. Such a fundamental shift in proposing microbiome-informed psychotropic prescriptions to optimise therapeutic efficacy and reduce adverse metabolic impacts would align antipsychotic treatments with microbiome safety, prioritising 'gut-neutral' or gut-favourable drugs to safeguard long-term patient outcomes in schizophrenia therapy.

Leveraging metabolism for better outcomes in heart failure

Whilst metabolic inflexibility and substrate constraint have been observed in heart failure for many years, their exact causal role remains controversial. In parallel, many of our fundamental assumptions about cardiac fuel use are now being challenged like never before. For example, the emergence of sodium-glucose cotransporter 2 inhibitor therapy as one of the four 'pillars' of heart failure therapy is causing a revisit of metabolism as a key mechanism and therapeutic target in heart failure. Improvements in the field of cardiac metabolomics will lead to a far more granular understanding of the mechanisms underpinning normal and abnormal human cardiac fuel use, an appreciation of drug action, and novel therapeutic strategies. Technological advances and expanding biorepositories offer exciting opportunities to elucidate the novel aspects of these metabolic mechanisms. Methodologic advances include comprehensive and accurate substrate quantitation such as metabolomics and stable-isotope fluxomics, improved access to arterio-venous blood samples across the heart to determine fuel consumption and energy conversion, high quality cardiac tissue biopsies, biochemical analytics, and informatics. Pairing these technologies with recent discoveries in epigenetic regulation, mitochondrial dynamics, and organ-microbiome metabolic crosstalk will garner critical mechanistic insights in heart failure. In this state-of-the-art review, we focus on new metabolic insights, with an eye on emerging metabolic strategies for heart failure. Our synthesis of the field will be valuable for a diverse audience with an interest in cardiac metabolism.

Revisiting the Concepts of Prebiotic and Prebiotic Effect in Light of Scientific and Regulatory Progress-A Consensus Paper From the Global Prebiotic Association

The term prebiotic has been used for almost 3 decades and has undergone numerous updates over the years. The scientific literature reveals that despite continuous efforts to establish a globally unified definition to guide jurisdictional regulations and product innovations, ambiguity continues to surround the terms prebiotic and prebiotic effect, leading to products that lack in full regulatory adherence being marketed worldwide. Thus, to reflect the current state of scientific research and knowledge and for the continuous advancement of the category, an update to the current prebiotic definition is warranted. This update includes removing the term selectivity, considering additional locations of action besides the gut, highlighting prebiotic performance benefits such as cognitive and athletic, and providing a clear standalone definition for prebiotic effect. The Global Prebiotic Association (GPA) is a leading information and industry hub committed to raising awareness about prebiotics, their emerging and well-established health benefits, and prebiotic product integrity and efficacy. In this position paper, GPA builds on previous prebiotic definitions to propose the following expanded definition for prebiotic: "a compound or ingredient that is utilized by the microbiota producing a health or performance benefit." In addition to prebiotic, GPA also defines prebiotic effect as "a health or performance benefit that arises from alteration of the composition and/or activity of the microbiota, as a direct or indirect result of the utilization of a specific and well-defined compound or ingredient by microorganisms." With these 2 definitions, GPA aims to paint a clearer picture for the term prebiotic, and by incorporating an industry point of view, these updated definitions may be used alongside current scientific and regulatory perspectives to move the category forward.

Recent advancements in targeting the immune system to treat hypertension

Hypertension is the key leading risk factor for death globally, affecting ∼1.3 billion adults, particularly in low- and middle-income countries. Most people living with hypertension have uncontrolled high blood pressure, increasing their likelihood of cardiovascular events. Significant issues preventing blood pressure control include lack of diagnosis, treatment, and response to existing therapy. For example, monotherapy and combination therapy are often unable to lower blood pressure to target levels. New therapies are urgently required to tackle this issue, particularly those that target the mechanisms behind hypertension instead of treating its symptoms. Acting via an increase in systemic and tissue-specific inflammation, the immune system is a critical contributor to blood pressure regulation and is considered an early mechanism leading to hypertension development. Here, we review the immune system's role in hypertension, evaluate clinical trials that target inflammation, and discuss knowledge gaps in pre-clinical and clinical data. We examine the effects of anti-inflammatory drugs colchicine and methotrexate on hypertension and evaluate the blockade of pro-inflammatory cytokines IL-1β and TNF-α on blood pressure in clinical trials. Lastly, we highlight how we can move forward to target specific components of the immune system to lower blood pressure. This includes targeting isolevuglandins, which accumulate in dendritic cells to promote T cell activation and cytokine production in salt-induced hypertension. We discuss the potential of the dietary fibre-derived metabolites short-chain fatty acids, which have anti-inflammatory and blood pressure-lowering effects via the gut microbiome. This would limit adverse events, leading to improved medication adherence and better blood pressure control.

Metformin modulates microbiota and improves blood pressure and cardiac remodeling in a rat model of hypertension

AIMS

Metformin has been attributed to cardiovascular protection even in the absence of diabetes. Recent observations suggest that metformin influences the gut microbiome. We aimed to investigate the influence of metformin on the gut microbiota and hypertensive target organ damage in hypertensive rats.

METHODS

Male double transgenic rats overexpressing the human renin and angiotensinogen genes (dTGR), a model of angiotensin II-dependent hypertension, were treated with metformin (300 mg/kg/day) or vehicle from 4 to 7 weeks of age. We assessed gut microbiome composition and function using shotgun metagenomic sequencing and measured blood pressure via radiotelemetry. Cardiac and renal organ damage and inflammation were evaluated by echocardiography, histology, and flow cytometry.

RESULTS

Metformin treatment increased the production of short-chain fatty acids (SCFA) acetate and propionate in feces without altering microbial composition and diversity. It significantly reduced systolic and diastolic blood pressure and improved cardiac function, as measured by end-diastolic volume, E/A, and stroke volume despite increased cardiac hypertrophy. Metformin reduced cardiac inflammation by lowering macrophage infiltration and shifting macrophage subpopulations towards a less inflammatory phenotype. The observed improvements in blood pressure, cardiac function, and inflammation correlated with fecal SCFA levels in dTGR. In vitro, acetate and propionate altered M1-like gene expression in macrophages, reinforcing anti-inflammatory effects. Metformin did not affect hypertensive renal damage or microvascular structure.

CONCLUSION

Metformin modulated the gut microbiome, increased SCFA production, and ameliorated blood pressure and cardiac remodeling in dTGR. Our findings confirm the protective effects of metformin in the absence of diabetes, highlighting SCFA as a potential mediators.

Constipation is associated with an increased risk of major adverse cardiac events in a UK population

Traditional cardiovascular risk factors, including hypertension, only explain part of major adverse cardiac events (MACEs). Understanding what other risk factors contribute to MACE is essential for prevention. Constipation shares common risk factors with hypertension and is associated with an increased risk of several cardiovascular diseases. We hypothesized that constipation is an underappreciated risk factor for MACE. We used the population healthcare and genomic data in the UK Biobank (n = 408,354) to study the contribution of constipation (ICD10 K59.0) to the risk of MACE, defined by any episode of acute coronary syndrome (ACS), ischemic stroke, and heart failure (HF). Analyses were controlled for traditional cardiovascular risk factors. We also assessed genetic correlations (rg) between constipation and MACE. Constipation cases (n = 23,814) exhibited a significantly higher risk of MACE compared with those with normal bowel habits [odds ratio (OR) = 2.15, P < 1.00 × 10-300]. Constipation was also significantly associated with individual MACE subgroups, in order: HF (OR = 2.72, P < 1.00 × 10-300), ischemic stroke (OR = 2.36, P = 2.02 × 10-230), and ACS (OR = 1.62, P = 5.82 × 10-113). In comparison with patients with constipation-free hypertension, patients with hypertension with constipation showed significantly higher odds of MACE (OR = 1.68, P = 1.05 × 10-136) and a 34% increased risk of MACE occurrence (P = 2.3 × 10-50) after adjustment for medications that affect gut motility and other traditional cardiovascular risk factors. Finally, we detected positive genetic correlations between constipation and MACE subgroups ACS (rg = 0.27, P = 2.12 × 10-6), ischemic stroke (rg = 0.23, P = 0.011), and HF (rg = 0.21, P = 0.0062). We identified constipation as a potential risk factor independently associated with higher MACE prevalence. These findings warrant further studies on their causal relationship and identification of pathophysiological mechanisms.NEW & NOTEWORTHY Analyzing 408,354 participants of the UK Biobank, we show that constipation cases exhibited a significantly higher risk of major adverse cardiac events (MACEs) than those with regular bowel habits. In comparison with patients with constipation-free hypertension, patients with hypertension with constipation showed significantly higher odds of MACE and a 34% increased risk of subsequent MACE occurrence. Finally, we detected positive genetic correlations between constipation and MACE. This association holds potential for therapeutic exploitation and prevention based on individuals' risk assessment.

Influence of angiotensin II on the gut microbiome: modest effects in comparison to experimental factors

AIMS

Animal models are regularly used to test the role of the gut microbiome in hypertension. Small-scale pre-clinical studies have investigated changes to the gut microbiome in the angiotensin II hypertensive model. However, the gut microbiome is influenced by internal and external experimental factors, which are not regularly considered in the study design. Once these factors are accounted for, it is unclear if microbiome signatures are reproduceable. We aimed to determine the influence of angiotensin II treatment on the gut microbiome using a large and diverse cohort of mice and to quantify the magnitude by which other factors contribute to microbiome variations.

METHODS AND RESULTS

We conducted a retrospective study to establish a diverse mouse cohort resembling large human studies. We sequenced the V4 region of the 16S rRNA gene from 538 samples across the gastrointestinal tract of 303 male and female C57BL/6J mice randomized into sham or angiotensin II treatment from different genotypes, diets, animal facilities, and age groups. Analysing over 17 million sequencing reads, we observed that angiotensin II treatment influenced α-diversity (P = 0.0137) and β-diversity (i.e. composition of the microbiome, P < 0.001). Bacterial abundance analysis revealed patterns consistent with a reduction in short-chain fatty acid producers, microbial metabolites that lower blood pressure. Furthermore, animal facility, genotype, diet, age, sex, intestinal sampling site, and sequencing batch had significant effects on both α- and β-diversity (all P < 0.001). Sampling site (6.8%) and diet (6%) had the largest impact on the microbiome, while angiotensin II and sex had the smallest effect (each 0.4%).

CONCLUSION

Our large-scale data confirmed findings from small-scale studies that angiotensin II impacted the gut microbiome. However, this effect was modest relative to most of the other factors studied. Accounting for these factors in future pre-clinical hypertensive studies will increase the likelihood that microbiome findings are replicable and translatable.

The gut-immune axis during hypertension and cardiovascular diseases

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

Recommendations for the Use of Dietary Fiber to Improve Blood Pressure Control

According to several international, regional, and national guidelines on hypertension, lifestyle interventions are the first-line treatment to lower blood pressure (BP). Although diet is one of the major lifestyle modifications described in hypertension guidelines, dietary fiber is not specified. Suboptimal intake of foods high in fiber, such as in Westernized diets, is a major contributing factor to mortality and morbidity of noncommunicable diseases due to higher BP and cardiovascular disease. In this review, we address this deficiency by examining and advocating for the incorporation of dietary fiber as a key lifestyle modification to manage elevated BP. We explain what dietary fiber is, review the existing literature that supports its use to lower BP and prevent cardiovascular disease, describe the mechanisms involved, propose evidence-based target levels of fiber intake, provide examples of how patients can achieve the recommended targets, and discuss outstanding questions in the field. According to the evidence reviewed here, the minimum daily dietary fiber for adults with hypertension should be >28 g/day for women and >38 g/day for men, with each extra 5 g/day estimated to reduce systolic BP by 2.8 mm Hg and diastolic BP by 2.1 mm Hg. This would support a healthy gut microbiota and the production of gut microbiota-derived metabolites called short-chain fatty acids that lower BP. Awareness about dietary fiber targets and how to achieve them will guide medical teams on better educating patients and empowering them to increase their fiber intake and, as a result, lower their BP and cardiovascular disease risk.

The role of gut microbiota in the development of salt-sensitive hypertension and the possible preventive effect of exercise

INTRODUCTION

The aim of the present study is to analyze the data indicating an association between high salt intake and the gastrointestinal microbiota in the development of salt-sensitive hypertension in animals and men. It is also, to discuss the preventive effects of exercise on gut-induced hypertension by favorably modifying the composition of gut microbiota.

AREAS COVERED

Salt sensitivity is quite common, accounting for 30%-60% in hypertensive subjects. Recently, a novel cause for salt-sensitive hypertension has been discovered through the action of gut microbiota by the secretion of several hormones and the action of short chain fatty acids (SCFAs). In addition, recent studies indicate that exercise might favorably modify the adverse effects of gut microbiota regarding their effects on BP. To identify the role of gut microbiota on the incidence of hypertension and CVD and the beneficial effect of exercise, a Medline search of the English literature was conducted between 2018 and 2023 and 42 pertinent papers were selected.

EXPERT OPINION

The analysis of data from the selected papers disclosed that the gut microbiota contribute significantly to the development of salt-sensitive hypertension and that exercise modifies their gut composition and ameliorates their adverse effects on BP.

Immune and inflammatory mechanisms in hypertension

Hypertension is a global health problem, with >1.3 billion individuals with high blood pressure worldwide. In this Review, we present an inflammatory paradigm for hypertension, emphasizing the crucial roles of immune cells, cytokines and chemokines in disease initiation and progression. T cells, monocytes, macrophages, dendritic cells, B cells and natural killer cells are all implicated in hypertension. Neoantigens, the NLRP3 inflammasome and increased sympathetic outflow, as well as cytokines (including IL-6, IL-7, IL-15, IL-18 and IL-21) and a high-salt environment, can contribute to immune activation in hypertension. The activated immune cells migrate to target organs such as arteries (especially the perivascular fat and adventitia), kidneys, the heart and the brain, where they release effector cytokines that elevate blood pressure and cause vascular remodelling, renal damage, cardiac hypertrophy, cognitive impairment and dementia. IL-17 secreted by CD4+ T helper 17 cells and γδ T cells, and interferon-γ and tumour necrosis factor secreted by immunosenescent CD8+ T cells, exert crucial effector roles in hypertension, whereas IL-10 and regulatory T cells are protective. Effector mediators impair nitric oxide bioavailability, leading to endothelial dysfunction and increased vascular contractility. Inflammatory effector mediators also alter renal sodium and water balance and promote renal fibrosis. These mechanisms link hypertension with obesity, autoimmunity, periodontitis and COVID-19. A comprehensive understanding of the immune and inflammatory mechanisms of hypertension is crucial for safely and effectively translating the findings to clinical practice.

Short-Chain Fatty Acid Butyrate Is an Inotropic Agent With Vasorelaxant and Cardioprotective Properties

BACKGROUND

The heart can metabolize the microbiota-derived short-chain fatty acid butyrate. Butyrate may have beneficial effects in heart failure, but the underlying mechanisms are unknown. We tested the hypothesis that butyrate elevates cardiac output by mechanisms involving direct stimulation of cardiac contractility and vasorelaxation in rats.

METHODS AND RESULTS

We examined the effects of butyrate on (1) in vivo hemodynamics using parallel echocardiographic and invasive blood pressure measurements, (2) isolated perfused hearts in Langendorff systems under physiological conditions and after ischemia and reperfusion, and (3) isolated coronary arteries mounted in isometric wire myographs. We tested Na-butyrate added to injection solutions or physiological buffers and compared its effects with equimolar doses of NaCl. Butyrate at plasma concentrations of 0.56 mM increased cardiac output by 48.8±14.9%, stroke volume by 38.5±12.1%, and left ventricular ejection fraction by 39.6±6.2%, and lowered systemic vascular resistance by 33.5±6.4% without affecting blood pressure or heart rate in vivo. In the range between 0.1 and 5 mM, butyrate increased left ventricular systolic pressure by up to 23.7±3.4% in isolated perfused hearts and by 9.4±2.9% following ischemia and reperfusion, while reducing myocardial infarct size by 81.7±16.9%. Butyrate relaxed isolated coronary septal arteries concentration dependently with an EC50=0.57 mM (95% CI, 0.23-1.44).

CONCLUSIONS

We conclude that butyrate elevates cardiac output through mechanisms involving increased cardiac contractility and vasorelaxation. This effect of butyrate was not associated with adverse myocardial injury in damaged hearts exposed to ischemia and reperfusion.

Unravelling the Link between the Gut Microbiome and Autoimmune Kidney Diseases: A Potential New Therapeutic Approach

The gut microbiota and short chain fatty acids (SCFA) have been associated with immune regulation and autoimmune diseases. Autoimmune kidney diseases arise from a loss of tolerance to antigens, often with unclear triggers. In this review, we explore the role of the gut microbiome and how disease, diet, and therapy can alter the gut microbiota consortium. Perturbations in the gut microbiota may systemically induce the translocation of microbiota-derived inflammatory molecules such as liposaccharide (LPS) and other toxins by penetrating the gut epithelial barrier. Once in the blood stream, these pro-inflammatory mediators activate immune cells, which release pro-inflammatory molecules, many of which are antigens in autoimmune diseases. The ratio of gut bacteria Bacteroidetes/Firmicutes is associated with worse outcomes in multiple autoimmune kidney diseases including lupus nephritis, MPO-ANCA vasculitis, and Goodpasture's syndrome. Therapies that enhance SCFA-producing bacteria in the gut have powerful therapeutic potential. Dietary fiber is fermented by gut bacteria which in turn release SCFAs that protect the gut barrier, as well as modulating immune responses towards a tolerogenic anti-inflammatory state. Herein, we describe where the current field of research is and the strategies to harness the gut microbiome as potential therapy.

Microbial influence on blood pressure: unraveling the complex relationship for health insights

Hypertension, a critical global health concern, is characterized by persistent high blood pressure and is a major cause of cardiovascular events. This perspective explores the multifaceted implications of hypertension, its association with cardiovascular diseases, and the emerging role of the gut microbiota. The gut microbiota, a dynamic community in the gastrointestinal tract, plays a pivotal role in hypertension by influencing blood pressure through the generation of antioxidant, anti-inflammatory, and short-chain fatty acids metabolites, and the conversion of nitrates into nitric oxide. Antihypertensive medications interact with the gut microbiota, impacting drug pharmacokinetics and efficacy. Prebiotics and probiotics present promising avenues for hypertension management, with prebiotics modulating blood pressure through lipid and cholesterol modulation, and probiotics exhibiting a general beneficial effect. Personalized choices based on individual factors are crucial for optimizing prebiotic and probiotic interventions. In conclusion, the gut microbiota's intricate influence on blood pressure regulation offers innovative perspectives in hypertension therapeutics, with targeted strategies proving valuable for holistic blood pressure management and health promotion.

Lactobacillus induced by irbesartan on spontaneously hypertensive rat contribute to its antihypertensive effect

OBJECTIVE

Hypertension is linked to gut dysbiosis. Here, the impact of the angiotensin receptor antagonist irbesartan on the gut microbiota of spontaneously hypertensive rats (SHR) were investigated. In addition, we assessed their contribution to its antihypertensive effect.

METHODS

Eight-week-old Wistar-Kyoto (WKY) rats and SHR were administered irbesartan for 8 weeks. Fecal microbiota transplantation (FMT) was performed from SHR treated with irbesartan or untreated SHR to recipient untreated SHR. The preventive effect of Lactobacillus on hypertension in SHR was evaluated. Blood pressure (BP) was calculated using a tail-sleeve sphygmomanometer. To better assess the composition of the gut microbiota, the V3-V4 region of the 16S rRNA gene was amplified while short-chain fatty acids (SCFAs) in feces were tested by liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS).

RESULTS

Irbesartan restored gut dysbiosis, increased the abundance of Lactobacillus , and improved anti-inflammatory ability, antioxidative ability, intestinal integrity, and intestinal inflammation in SHR. The microbiota in SHR-treated irbesartan could reduce BP and improve antioxidative ability and gut integrity in SHR. Lactobacillus johnsonii ( L. johnsonii ) and Lactobacillus reuteri ( L. reuteri ) reduced BP, restored gut dysbiosis and improved anti-inflammatory ability, antioxidative ability, intestinal integrity in SHR. Most notably, irbesartan, L. johnsonii , and L. reuteri can significantly increase SCFA content in SHR feces.

CONCLUSION

The current study demonstrated that irbesartan treatment ameliorated gut dysbiosis in SHR. Irbesartan induced alterations in gut microbiota, with increased prevalence of Lactobacillus .

Unraveling the gut health puzzle: exploring the mechanisms of butyrate and the potential of High-Amylose Maize Starch Butyrate (HAMSB) in alleviating colorectal disturbances

Colorectal disturbances encompass a variety of disorders that impact the colon and rectum, such as colitis and colon cancer. Butyrate, a short-chain fatty acid, plays a pivotal role in supporting gut health by nourishing colonocytes, promoting barrier function, modulating inflammation, and fostering a balanced microbiome. Increasing colorectal butyrate concentration may serve as a critical strategy to improve colon function and reduce the risk of colorectal disturbances. Butyrylated high-amylose maize starch (HAMSB) is an edible ingredient that efficiently delivers butyrate to the colon. HAMSB is developed by esterifying a high-amylose starch backbone with butyric anhydride. With a degree of substitution of 0.25, each hydroxy group of HAMSB is substituted by a butyryl group in every four D-glucopyranosyl units. In humans, the digestibility of HAMSB is 68% (w/w), and 60% butyrate molecules attached to the starch backbone is absorbed by the colon. One clinical trial yielded two publications, which showed that HAMSB significantly reduced rectal O6-methyl-guanine adducts and epithelial proliferation induced by the high protein diet. Fecal microbial profiles were assessed in three clinical trials, showing that HAMSB supplementation was consistently linked to increased abundance of Parabacteroides distasonis. In animal studies, HAMSB was effective in reducing the risk of diet- or AOM-induced colon cancer by reducing genetic damage, but the mechanisms differed. HAMSB functioned through affecting cecal ammonia levels by modulating colon pH in diet-induced cancer, while it ameliorated chemical-induced colon cancer through downregulating miR19b and miR92a expressions and subsequently activating the caspase-dependent apoptosis. Furthermore, animal studies showed that HAMSB improved colitis via regulating the gut immune modulation by inhibiting histone deacetylase and activating G protein-coupled receptors, but its role in bacteria-induced colon colitis requires further investigation. In conclusion, HAMSB is a food ingredient that may deliver butyrate to the colon to support colon health. Further clinical trials are warranted to validate earlier findings and determine the minimum effective dose of HAMSB.

An Analysis of the Gut Microbiota and Related Metabolites following PCSK9 Inhibition in Statin-Treated Patients with Elevated Levels of Lipoprotein(a)

BACKGROUND

Atherosclerotic cardiovascular disease (ASCVD) is a leading cause of global mortality, often associated with high blood levels of LDL cholesterol (LDL-c). Medications like statins and PCSK9 inhibitors, are used to manage LDL-c levels and reduce ASCVD risk. Recent findings connect the gut microbiota and its metabolites to ASCVD development. We showed that statins modulate the gut microbiota including the production of microbial metabolites involved in the regulation of cholesterol metabolism such as short chain fatty acids (SCFAs) and bile acids (BAs). Whether this pleiotropic effect of statins is associated with their antimicrobial properties or it is secondary to the modulation of cholesterol metabolism in the host is unknown. In this observational study, we evaluated whether alirocumab, a PCSK9 inhibitor administered subcutaneously, alters the stool-associated microbiota and the profiles of SCFAs and BAs.

METHODS

We used stool and plasma collected from patients enrolled in a single-sequence study using alirocumab. Microbial DNA was extracted from stool, and the bacterial component of the gut microbiota profiled following an amplicon sequencing strategy targeting the V3-V4 region of the 16S rRNA gene. Bile acids and SCFAs were profiled and quantified in stool and plasma using mass spectrometry.

RESULTS

Treatment with alirocumab did not alter bacterial alpha (Shannon index, p = 0.74) or beta diversity (PERMANOVA, p = 0.89) in feces. Similarly, circulating levels of SCFAs (mean difference (95% confidence interval (CI)), 8.12 [-7.15-23.36] µM, p = 0.25) and BAs (mean difference (95% CI), 0.04 [-0.11-0.19] log10(nmol mg-1 feces), p = 0.56) were equivalent regardless of PCSK9 inhibition. Alirocumab therapy was associated with increased concentration of BAs in feces (mean difference (95% CI), 0.20 [0.05-0.34] log10(nmol mg-1 feces), p = 0.01).

CONCLUSION

In statin-treated patients, the use of alirocumab to inhibit PCSK9 leads to elevated levels of fecal BAs without altering the bacterial population of the gut microbiota. The association of alirocumab with increased fecal BA concentration suggests an additional mechanism for the cholesterol-lowering effect of PCSK9 inhibition.

Dietary fiber intake impacts gut bacterial and viral populations in a hypertensive mouse model

The gut microbiome is an emerging factor in preventing hypertension, yet the influence of gut bacteriophages, viruses infecting bacteria, on this condition remains unclear. Bacteriophage-bacteria interactions, which impact the gut microbiome, are influenced differentially by temperate and virulent bacteriophages. However, the standard technique for studying viral populations, viral-like particles (VLPs)-metagenomes, often overlook prophages, the intracellular stage of temperate bacteriophages, creating a knowledge gap. To address this, we investigated alterations in extracellular and intracellular bacteriophages, alongside bacterial populations, in the angiotensin II-hypertension model. We sequenced VLPs and bulk DNA from cecal-colonic samples collected from male C57BL/6J mice implanted with minipumps containing saline or angiotensin II. We assembled 106 bacterial and 816 viral genomes and found that gut viral and bacterial populations remained stable between hypertensive and normotensive mice. A higher number of temperate viruses were observed across all treatments. Although temperate viruses outnumbered virulent viruses, sequencing of both VLPs and bulk revealed that virions from virulent viruses were more abundant in the murine gut. We then evaluated the impact of low- and high-fiber intake on gut microbiome composition in the angiotensin II model. Fiber intake significantly influenced the gut microbiome composition and hypertension development. Mice receiving high-fiber had lower blood pressure, a higher bacterial-encoded carbohydrate-associated enzyme, and a higher total relative abundance of temperate viruses than those receiving low-fiber. Our findings suggest that phages are not associated with hypertension development in the angiotensin II model. However, they support a complex diet-bacteria/phage interaction that may be involved in blood pressure regulation.

Salty Subjects: Unpacking Racial Differences in Salt-Sensitive Hypertension

PURPOSE OF REVIEW

To review underlying mechanisms and environmental factors that may influence racial disparities in the development of salt-sensitive blood pressure.

RECENT FINDINGS

Our group and others have observed racial differences in diet and hydration, which may influence salt sensitivity. Dietary salt elicits negative alterations to the gut microbiota and immune system, which may increase hypertension risk, but little is known regarding potential racial differences in these physiological responses. Antioxidant supplementation and exercise offset vascular dysfunction following dietary salt, including in Black adults. Furthermore, recent work proposes the role of racial differences in exposure to social determinants of health, and differences in health behaviors that may influence risk of salt sensitivity. Physiological and environmental factors contribute to the mechanisms that manifest in racial differences in salt-sensitive blood pressure. Using this information, additional work is needed to develop strategies that can attenuate racial disparities in salt-sensitive blood pressure.

Lifestyle management of hypertension: International Society of Hypertension position paper endorsed by the World Hypertension League and European Society of Hypertension

Hypertension, defined as persistently elevated systolic blood pressure (SBP) >140 mmHg and/or diastolic blood pressure (DBP) at least 90 mmHg (International Society of Hypertension guidelines), affects over 1.5 billion people worldwide. Hypertension is associated with increased risk of cardiovascular disease (CVD) events (e.g. coronary heart disease, heart failure and stroke) and death. An international panel of experts convened by the International Society of Hypertension College of Experts compiled lifestyle management recommendations as first-line strategy to prevent and control hypertension in adulthood. We also recommend that lifestyle changes be continued even when blood pressure-lowering medications are prescribed. Specific recommendations based on literature evidence are summarized with advice to start these measures early in life, including maintaining a healthy body weight, increased levels of different types of physical activity, healthy eating and drinking, avoidance and cessation of smoking and alcohol use, management of stress and sleep levels. We also discuss the relevance of specific approaches including consumption of sodium, potassium, sugar, fibre, coffee, tea, intermittent fasting as well as integrated strategies to implement these recommendations using, for example, behaviour change-related technologies and digital tools.

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.

Gut Microbiota and Its Role in the Brain-Gut-Kidney Axis in Hypertension

PURPOSE OF REVIEW

The role of the gut microbiota in modulating blood pressure is increasingly being recognized, currently. The purpose of this review is to summarize recent findings about the mechanisms involved in hypertension with regard to the phenomenon of "gut dysbiosis."

RECENT FINDINGS

Gut dysbiosis, i.e., the imbalance between the gut microbiota and the host, is characterized by a disruption of the tight junction proteins, such as occludins, claudins, and JAMs (junctional adhesion molecules), resulting in increased gut permeability or the so called "leaky gut." Due to the influence of genetic as well as environmental factors, various metabolites produced by the gut microbiota, such as indole and p-cresol, are increased. Thereby, uremic toxins, such as indoxyl sulfates and p-cresol sulfates, accumulate in the blood and the urine, causing damage in the podocytes and the tubular cells. In addition, immunological mechanisms are implicated as well. In particular, a switch from M2 macrophages to M1 macrophages, which produce pro-inflammatory cytokines, occurs. Moreover, a higher level of Th17 cells, releasing large amounts of interleukin-17 (IL-17), has been reported, when a diet rich in salt is consumed. Therefore, apart from the aggravation of uremic toxins, which may account for direct harmful effects on the kidney, there is inflammation not only in the gut, but in the kidneys as well. This crosstalk between the gut and the kidney is suggested to play a crucial role in hypertension. Notably, the brain is also implicated, with an increasing sympathetic output. The brain-gut-kidney axis seems to be deeply involved in the development of hypertension and chronic kidney disease (CKD). The notion that, by modulating the gut microbiota, we could regulate blood pressure is strongly supported by the current evidence. A healthy diet, low in animal protein and fat, and low in salt, together with the utilization of probiotics, prebiotics, synbiotics, or postbiotics, may contribute to our fight against hypertension.

Microbiome-targeted interventions for the control of oral-gut dysbiosis and chronic systemic inflammation

Recent research has confirmed the strong connection between imbalances in the oral and gut microbiome (oral-gut dysbiosis), periodontitis, and inflammatory conditions such as diabetes, Alzheimer's disease, and cardiovascular diseases. Microbiome modulation is crucial for preventing and treating several autoimmune and inflammatory diseases, including periodontitis. However, the causal relationships between the microbiome and its derived metabolites that mediate periodontitis and chronic inflammation constitute a notable knowledge gap. Here we review the mechanisms involved in the microbiome-host crosstalk, and describe novel precision medicine for the control of systemic inflammation. As microbiome-targeted therapies begin to enter clinical trials, the success of these approaches relies upon understanding these reciprocal microbiome-host interactions, and it may provide new therapeutic avenues to reduce the risk of periodontitis-associated diseases.

The Gut-Organ Axis within the Human Body: Gut Dysbiosis and the Role of Prebiotics

The human gut microbiota (GM) is a complex microbial ecosystem that colonises the gastrointestinal tract (GIT) and is comprised of bacteria, viruses, fungi, and protozoa. The GM has a symbiotic relationship with its host that is fundamental for body homeostasis. The GM is not limited to the scope of the GIT, but there are bidirectional interactions between the GM and other organs, highlighting the concept of the "gut-organ axis". Any deviation from the normal composition of the GM, termed "microbial dysbiosis", is implicated in the pathogenesis of various diseases. Only a few studies have demonstrated a relationship between GM modifications and disease phenotypes, and it is still unknown whether an altered GM contributes to a disease or simply reflects its status. Restoration of the GM with probiotics and prebiotics has been postulated, but evidence for the effects of prebiotics is limited. Prebiotics are substrates that are "selectively utilized by host microorganisms, conferring a health benefit". This study highlights the bidirectional relationship between the gut and vital human organs and demonstrates the relationship between GM dysbiosis and the emergence of certain representative diseases. Finally, this article focuses on the potential of prebiotics as a target therapy to manipulate the GM and presents the gaps in the literature and research.

Lifestyle Medicine as a Treatment for Resistant Hypertension

PURPOSE OF REVIEW

Approximately 10% of the adults with hypertension fail to achieve the recommended blood pressure treatment targets on 3 antihypertensive medications or require ≥ 4 medications to achieve goal. These patients with 'resistant hypertension' have an increased risk of target organ damage, adverse clinical events, and all-cause mortality. Although lifestyle modification is widely recommended as a first-line approach for the management of high blood pressure, the effects of lifestyle modifications in patients with resistant hypertension has not been widely studied. This review aims to provide an overview of the emerging evidence on the benefits of lifestyle modifications in patients with resistant hypertension, reviews potential mechanisms by which lifestyles may reduce blood pressure, and discusses the clinical implications of the recent findings in this field.

RECENT FINDINGS

Evidence from single-component randomized clinical trials demonstrated that aerobic exercise, weight loss and dietary modification can reduce clinic and ambulatory blood pressure in patients with resistant hypertension. Moreover, evidence from multi-component trials involving exercise and dietary modification and weight management can facilitate lifestyle change, reduce clinic and ambulatory blood pressure, and improve biomarkers of cardiovascular risk. This new evidence supports the efficacy of lifestyle modifications added to optimized medical therapy in reducing blood pressure and improving cardiovascular risk biomarkers in patients with resistant hypertension. These findings need to be confirmed in larger studies, and the persistence of benefit over extended follow-up needs further study.

Novel mechanisms of salt-sensitive hypertension

A high dietary sodium-consumption level is considered the most important lifestyle factor that can be modified to help prevent an increase in blood pressure and the development of hypertension. Despite numerous studies over the past decades, the pathophysiology explaining why some people show a salt-sensitive blood pressure response and others do not is incompletely understood. Here, a brief overview of the latest mechanistic insights is provided, focusing on the mononuclear phagocytic system and inflammation, the gut-kidney axis, and epigenetics. The article also discusses the effects of 3 types of novel drugs on salt-sensitive hypertension-sodium-glucose cotransporter 2 inhibitors, nonsteroidal mineralocorticoid receptor antagonists, and aldosterone synthase inhibitors. The conclusion is that besides kidney-centered mechanisms, vasoconstrictor mechanisms are also relevant for both the understanding and treatment of this blood pressure phenotype.

Guidelines for microbiome studies in renal physiology

Gut microbiome research has increased dramatically in the last decade, including in renal health and disease. The field is moving from experiments showing mere association to causation using both forward and reverse microbiome approaches, leveraging tools such as germ-free animals, treatment with antibiotics, and fecal microbiota transplantations. However, we are still seeing a gap between discovery and translation that needs to be addressed, so that patients can benefit from microbiome-based therapies. In this guideline paper, we discuss the key considerations that affect the gut microbiome of animals and clinical studies assessing renal function, many of which are often overlooked, resulting in false-positive results. For animal studies, these include suppliers, acclimatization, baseline microbiota and its normalization, littermates and cohort/cage effects, diet, sex differences, age, circadian differences, antibiotics and sweeteners, and models used. Clinical studies have some unique considerations, which include sampling, gut transit time, dietary records, medication, and renal phenotypes. We provide best-practice guidance on sampling, storage, DNA extraction, and methods for microbial DNA sequencing (both 16S rRNA and shotgun metagenome). Finally, we discuss follow-up analyses, including tools available, metrics, and their interpretation, and the key challenges ahead in the microbiome field. By standardizing study designs, methods, and reporting, we will accelerate the findings from discovery to translation and result in new microbiome-based therapies that may improve renal health.