Effect of probiotics on blood pressure: a systematic review and meta-analysis of randomized, controlled trials

Case Report: Miles Surgery Ameliorates High Blood Pressure in a Rectal Carcinoma Patient With Essential Hypertension

Hypertension is one of the major causes of public health problems. Multiple factors affecting gastrointestinal tract function are involved in hypertension. Emerging studies have manifested that gut intervention may play significant roles in regulating blood pressure but the underlying mechanisms are complex and not fully clear. Here, we report a case of 66 years old male who had a long history of hypertension and received Miles surgery for rectal carcinoma. The blood pressure of this patient was returned to normal levels after the operation. The possible reasons could be the modulation of sympathetic tone and the gut microbiota-brain axis. This report provides evidence about the relevance between hypertension and gut intervention particularly in the colorectal sites and gives hints for investigating the possible mechanisms of hypertension and the novel strategy for blood pressure control.

Impact of Gut Microbiota on the Risk of Cardiometabolic Diseases Development

Obesity is a multifactorial disease that leads to excessive adipose tissue accumulation, mainly visceral fat. Importance and prevalence of obesity has increased significantly in recent decades all over the world. Until now, the pandemic of obesity has been associated more to lifestyle changes: excessive eating and low physical activity. In recent years, special attention has been paid to studying of composition and functions of intestinal microbiota as major factor in development of obesity and related comorbidities, such as hypertension, cardiac ischemia, heart failure and others. It is proved that gut microbiota affects extraction, accumulation and consumption of energy derived from food, lipid metabolism and immune response. It is also revealed that composition of the microbiota is different in thin and obese people. Thus, study of the relationship between intestinal microbiota composition and risk factors for cardiovascular diseases, in particular obesity, is an actual task. The purpose of this review is analyzing of literature about assessment of relationship between composition and functions of intestinal microbiota in the diagnostics, prevention and treatment of obesity and cardiovascular diseases.

Interactive Effect of Probiotics Supplementation and Weight Loss Diet on Metabolic Syndrome Features in Patients With Coronary Artery Diseases: A Double-Blind, Placebo-Controlled, Randomized Clinical Trial

Background. Nutrition and probiotics supplementation are considered as nondrug strategies for the control of coronary artery disease (CAD). The aim of the present study was to investigate the interactive effects of probiotic supplementation and weight loss program on anthropometric and metabolic syndrome (MetS) indices in patients with CAD. Methods. A randomized, double-blind, placebo-controlled trial was performed in 44 overweight CAD patients. All the patients received weight loss program (5% to 10% of initial body weight) throughout the study course. The subjects were randomly assigned into intervention or placebo groups (n = 22, each) and received a probiotic or maltodextrin capsule/day, respectively, for 12 consecutive weeks. Anthropometric and MetS indices were assessed. Results. There was a significant decrease in total cholesterol (-30.7 ± 49.83 vs -5.9 ± 65 mmol/L, P = .043) and low-density lipoprotein cholesterol (-25.64 ± 51.7 vs -5.44 ± 70.1 mg/dL, P = .049) in the probiotic group compared to the placebo group. Other MetS feature indices and blood pressure did not differ significantly within or between groups. Conclusion. Probiotics supplementation improved total cholesterol and low-density lipoprotein cholesterol but had no effect on other lipid profile parameters and anthropometric indices. The weight loss diet plus probiotics supplementations resulted in more favorable decrease of cardiovascular risk factors compared to a weight loss program alone.

A Pilot Study of the Effect of Lactobacillus casei Obtained from Long-Lived Elderly on Blood Biochemical, Oxidative, and Inflammatory Markers, and on Gut Microbiota in Young Volunteers

Probiotic intake has been shown to improve certain physiological health indicators. We aimed to examine effects of Lactobacillus casei LTL1879, obtained from long-lived elderly volunteers, on blood biochemical, oxidative, and inflammatory markers and gut microbiota in twenty healthy, young volunteers. Volunteers were randomly divided into equal probiotic and placebo groups and changes in blood biochemical indicators, oxidative and inflammatory markers, and gut microbiota were examined after three weeks of probiotic intervention. The probiotic group’s antioxidant levels were significantly enhanced post-intervention. Total antioxidant capacity (T-AOC) levels were significantly increased (p < 0.0001), while malondialdehyde (MDA) levels decreased (p < 0.05), and total superoxide dismutase (T-SOD) levels increased, but with no significant difference. In addition, Interleukin-10 (IL-10) and tumor necrosis factor-α (TNF-α) levels were significantly up-regulated and down-regulated (p < 0.05, respectively). Escherichia coli, Enterococcus, and Bacteroides expression was significantly reduced (p < 0.05), while Clostridium leptum, Bifidobacterium, and Lactobacillus expression increased (p < 0.05). Volunteer health status was quantified using principal components and cluster analysis, indicating that the probiotic group’s overall score was higher than that of the placebo group. The results of this pilot study suggest L. casei LTL 1879 can significantly improve specific immune, oxidative, and gut microbiota characteristics related to health factors.

Association between gut dysbiosis and chronic kidney disease: a narrative review of the literature

Chronic kidney disease (CKD) is a serious non-communicable disease that poses a significant burden on healthcare and society. It is essential to devise new strategies to better treat patients with CKD. Research has illustrated that gut dysbiosis, describing an abnormal intestinal ecology, is closely associated with CKD. In this narrative review, we summarized the evidence of their mutual relationship and discussed the potential treatment options to correct gut dysbiosis in patients with CKD. Gut dysbiosis significantly increases the risk of CKD, especially in the older population. Gut dysbiosis also plays a role in CKD complications, such as hypertension, cardiovascular events, and cognitive dysfunction. The relationship between gut dysbiosis and CKD is bidirectional, and CKD itself can lead to changes in gut microecology. The usual therapies for CKD can also increase the incidence of gut dysbiosis. Meanwhile, probiotics and antibiotics are generally used to correct gut dysbiosis. Further studies are required to elaborate the association between gut dysbiosis and CKD, and more treatment options should be explored to prevent CKD in patients with gut dysbiosis.

Shaping the gut microbiota by bioactive phytochemicals: An emerging approach for the prevention and treatment of human diseases

The human digestive tract is the cottage to trillions of live microorganisms, which regulate health and illness. A healthy Gut Microbiota (GM) is necessary for preventing microbial growth, body growth, obesity, cancer, diabetes, and enhancing immunity. The equilibrium in GM's composition and the presence/absence of critical species enable specific responses to be essential for the host's better health condition. Research evidences revealed that the dietary plants and their bioactive phytochemicals (BPs) play an extensive and critical role in shaping the GM to get beneficial health effects. BPs are also known to improve gastrointestinal health and reduce the risk of several diseases by modulating GM-mediated cellular and molecular processes. Regular intake of BPs-rich vegetables, fruits, and herbal preparations promotes probiotic bacteria, including Bifidobacteria and Lactobacillus species, while inhibiting unwanted gut residents' development Escherichia coli, and Salmonella typhimurium etc. Upon consumption, BPs contact the GM that gets transformed before being absorbed from the gastrointestinal tract. Biotransformation of BPs by GM is linked with the enhancement of bioactivity/toxicity diminishment of the BPs compared to parental phytochemicals. Therefore, the current review focuses on the role of BPs in shaping GM for the prevention and treatment of human diseases.

Associations of imbalance of intestinal flora with severity of disease, inflammatory factors, adiponectin, and vascular endothelial function of hypertension patients

To explore the relationship between the severity of hypertension and the imbalanced intestinal flora, inflammatory factors, adiponectin (ADPN) and vascular endothelial function in primary hypertension patients. According to the grading criteria for hypertension, in total of 60 patients with primary hypertension in our hospital from April to July, 2020 were divided into Grade 1 group (n = 20), Grade 2 group (n = 20), and Grade 3 group (n = 20). The feces of the research subjects were collected to extract the deoxyribonucleic acid (DNA) and detect its composition of intestinal flora. Subsequently, the peripheral blood was collected to determine the changes in inflammatory factors interleukin-2 (IL-2), IL-4, tumor necrosis factor-α (TNF-α) and IL-1β, serum immunoglobulin G (IgG) and IgM, ADPN and vascular endothelial function-related endothelin-1 (ET-1), nitric oxide (NO), vascular endothelial growth factor (VEGF), and intercellular adhesion molecule-1 (ICAM-1). There were no significant differences in the gender, age, and body mass index (BMI), the proportion of smokers, diet habit, probiotics and antihypertensive medication use, and number of diabetic cases among groups (p > 0.05). We found an inverse association between blood pressure measures and microbial diversity, in particular microbial richness (p < 0.05). Among the four major kinds of intestinal flora, the composition of firmicutes (p < 0.05) and bacteroidetes (p < 0.05) showed obvious differences among the three groups, and they had consistent trends with the changes in the abundance of firmicutes and bacteroidetes. Intestinal flora imbalance is closely related to the severity of hypertension, inflammatory factors, ADPN, and vascular endothelial function.

Probiotic yogurt blunts the increase of blood pressure in spontaneously hypertensive rats via remodeling of the gut microbiota

Dietary intake of probiotic yogurt, which has beneficial effects on intestinal microecology, is associated with a lower incidence of hypertension. Recent studies have shown that the gut microbiota plays a vital role in the development of hypertension. However, the impact of the gut microbiota in the antihypertensive effect of probiotic yogurt remains unclear. Here, we evaluated the impact of the gut microbiota in the antihypertensive effect of probiotic yogurt in spontaneously hypertensive rats (SHR). SHR were treated with probiotic yogurt (0.2 mL per 100 g body weight) (SHR-Y group) for seven weeks and compared with whole milk-treated (0.2 mL per 100 g body weight) SHR (SHR group) and with normotensive Wistar-Kyoto rats (WKY group). The blood pressure and heart function of the rats in the WKY, SHR, and SHR-Y groups were measured. Fecal microbiota was assessed by 16S ribosomal RNA (16S rRNA) gene sequencing. To investigate whether probiotic yogurt prevents hypertension in spontaneously hypertensive rats through the gut microbiota, we co-housed SHR rats (SHR^COH) with SHR-Y rats (SHR^COH-Y), thus allowing the transfer of microbiota via coprophagy. Compared with whole milk, supplementation of probiotic yogurt significantly reduced the blood pressure, heart rate (HR), and cardiac function. We found that the probiotic yogurt modified the gut microbiota populations and increased the alpha diversity. Gut microbiota remodeling by co-housing partly rescued the increase of blood pressure and impaired the cardiac function of SHR rats. Moreover, probiotic yogurt modulated the gut microbiota in mice by increasing the abundance of short-chain fatty acid (SCFA)-producing bacteria and SCFA levels (acetic acid, propionic acid, butyric acid, and valeic acid) in the feces. Together, the presented data revealed that probiotic yogurt exhibited antihypertensive effects in SHR rats via remodeling of the gut microbiota.

The gut microbiota and nervous system: Age-defined and age-defying

Even healthy older adults experience gastrointestinal (GI) and neurological changes. In fact, the aging process of these two systems are interrelated due the extensive, multifaceted communication network connecting them, termed the gut-brain axis. Age-related modification of the GI environment can influence the bacterial species that survive and thrive there. Additionally, the lifestyle common to older adults in the West, including sedentariness, polypharmacy, and a poor diet, can compound the effect of aging on the GI tract, gut microbiota, and nervous system. Emerging animal and human findings suggest that GI organisms play a major role in gut-brain communication, ultimately shaping neurological aging trajectories by either helping to maintain nervous system function into late life or promoting pathology. Aging and age-related behaviors help to define the gut microbiota's composition and function, but, conversely, the gut microbiota may help to determine late-life functionality and may be harnessed to limit the prevalence of steep neurological decline and diseases. Focusing primarily on clinical research, this review first defines the gut-brain axis, then details age-related GI and nervous system changes, and discusses the impact of age-related lifestyle factors on the GI and nervous systems. The remainder of this review describes cutting-edge research that positions the gut microbiota as an arbiter of age-related neurological decline.

Effects of probiotics on body adiposity and cardiovascular risk markers in individuals with overweight and obesity: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND & AIMS

Evidence suggests that gut microbiota is a potential factor in the pathophysiology of both obesity and related metabolic disorders. While individual randomized controlled trials (RCTs) have evaluated the effects of probiotics on adiposity and cardiovascular disease (CVD) risk factors in subjects with overweight and obesity, the results are inconsistent. Thus, this systematic review and meta-analysis aimed to evaluate the effects of probiotic supplementation on body weight, body adiposity and CVD risk markers in overweight and obese subjects.

METHODS

A systematic search for RCTs published up to December 2020 was conducted in MEDLINE (via PubMed), EMBASE, Scopus and LILACS. Meta-analysis using a random-effects model was chosen to analyze the impact of combined trials.

RESULTS

Twenty-six RCTs (n = 1720) were included. Data pooling showed a significant effect of probiotics in reducing body weight (MD:-0.70 kg; 95%CI:-1.04,-0.35 kg; P < 0.0001), body mass index (BMI) (MD:-0.24 kg/m²; 95%CI:-0.35,-0.12 kg/m²; P = 0.0001), waist circumference (WC) (MD:-1.13 cm; 95%CI:-1.54,-0.73 cm; P < 0.0001), fat mass (MD:-0.71 kg; 95%CI:-1.10,-0.32 kg; P = 0.0004), tumor necrosis factor-α (MD:-0.16 pg/ml; 95%CI:-0.24,-0.08 pg/ml; P = 0.0001), insulin (MD:-0.85mcU/ml; 95%CI:-1.50,-0.21mcU/ml; P = 0.010), total cholesterol (MD:-0.16 mmol/l; 95%CI:-0.26,-0.05 mmol/l; P = 0.003) and LDL (MD:-0.09 mmol/l; 95%CI:-0.16,-0.03 mmol/l; P = 0.006) compared with control groups. There was a significant decrease in body weight, BMI and WC in studies using both single and multi-bacterial species. Decreases in body adiposity parameters were only observed in studies using a probiotic dose of ≥ 10¹⁰ CFU and for ≥8 weeks duration.

CONCLUSIONS

The present meta-analysis suggests that probiotics consumption may be helpful for improving body weight, body adiposity and some CVD risk markers in individuals with overweight and obesity. The review was registered on PROSPERO (International prospective register of systematic reviews): CRD42020183136.

Cigarette smoking status alters dysbiotic gut microbes in hypertensive patients

Smoking not only is one of the most important risk factors of hypertension (HTN), but also alters the composition of gut microbiota (GM) in previous studies. Although dysbiosis of GM has been implicated in HTN, how GM alters in patients with HTN under smoking status is still not clear. This study aimed to explore the difference in intestinal microflora among smokers with HTN (S-HTN), nonsmokers with HTN (NS-HTN), and smokers without HTN (S-CTR) and identify whether cigarette smoking led to disordered intestinal microbiota in patients with HTN. Metagenomic sequencing analysis of fecal specimens was conducted in nonsmokers without HTN (NS-CTR, n = 9), S-CTR (n = 9), NS-HTN (n = 18), and S-HTN (n = 23). Compared with S-CTR or NS-HTN, the GM in S-HTN was disordered, with lower microbial α-diversity and significant difference of β-diversity on axes as compared to S-CTR at genus and species level. The microbial enterotype in S-HTN was inclined to Prevotella-dominant type. Dramatic changes in the intestinal genera and species composition were observed in S-HTN, including reduced enrichment of Phycisphaera and Clostridium asparagiforme. Moreover, the intestinal function altered in S-HTN. Therefore, the findings of the present study revealed GM disorders in S-HTN and clarified the role of smoking in impairing the intestinal microbiome in HTN. Tobacco control is particularly important for improving GM in patients with HTN, and might be beneficial in preventing future cardiovascular events.

Role of the Gut Microbiota in Stroke Pathogenesis and Potential Therapeutic Implications

BACKGROUND

Major advances have been made in stroke treatment and prevention in the past decades. However, the burden of stroke remains high. Identification of novel targets and establishment of effective interventions to improve stroke outcomes are, therefore, needed. Recent research highlights the contribution of the gut microbiota to stroke pathogenesis.

SUMMARY

Compositional and functional alterations of the gut microbiota, termed dysbiosis, are linked to stroke risk factors, such as obesity, metabolic diseases, and atherosclerosis. In acute cerebral ischemia, the gut microbiota plays a key role in bidirectional interactions between the gut and brain, referred to as the microbiota-gut-brain axis. Gut dysbiosis prior to ischemic stroke affects outcomes. Additionally, the brain affects the gut microbiota during acute ischemic brain injury, which in turn impacts outcomes. Interactions between the gut microbiota and stroke pathogenesis are mediated by several factors including bacterial components (e.g., lipopolysaccharide), gut microbiota-related metabolites (e.g., short-chain fatty acids and trimethylamine N-oxide), and the immune and nervous systems. Clinical studies have reported that patients with acute ischemic stroke exhibit gut dysbiosis, which is associated with host metabolism and inflammation, as well as functional outcomes. Modulation of the gut microbiota or its metabolites improves conditions related to stroke pathogenesis, including inflammation, cardiometabolic disease, atherosclerosis, and thrombosis. Key Messages: Accumulating evidence indicates that the gut microbiota plays a possible role in stroke pathogenesis. Modulation of the gut microbiota may provide a novel therapeutic strategy for the treatment and prevention of stroke.

Effects of probiotic supplementation on anthropometric and metabolic characteristics in adults with metabolic syndrome: A systematic review and meta-analysis of randomized clinical trials

AIMS

We conducted a systematic review and meta-analysis to evaluate evidence from randomized controlled trials (RCTs) documenting the effectiveness of supplementation with pro-/synbiotics versus placebo controls on anthropometric and metabolic (glucoregulatory status, lipid profile) indices in adults with metabolic syndrome (MetS).

METHODS

Databases of MEDLINE, Scopus, Embase, Web of Science, and Cochrane Library were searched through March 2020 to identify eligible RCTs evaluating the effects of pro-/synbiotic consumption in adults (≥18 years) with MetS. Mean differences (MDs) and 95% confidence intervals (CIs) were pooled using random-effects models.

RESULTS

Ten eligible publications (9 RCTs, n = 344 participants) were included. Supplementation with pro-/synbiotics reduced total cholesterol (TC) in adults with MetS versus placebo (MD: -6.66 mg/dL, 95% CI: -13.25 to -0.07, P = 0.04, I² = 28.8%, n = 7), without affecting weight, body mass index, waist circumference, fasting blood sugar, homeostasis model assessment for insulin resistance, insulin, triglyceride, low-density lipoprotein cholesterol, or high-density lipoprotein cholesterol (P > 0.05).

CONCLUSIONS

Pro-/synbiotic consumption may be beneficial in reducing TC levels in adults with MetS. However, our observations do not support the effectiveness of pro-/synbiotics consumption on other anthropometric or metabolic outcomes of MetS. Further investigations with larger sample sizes are required to confirm these findings.

Impact of the Gut Microbiota Balance on the Health-Disease Relationship: The Importance of Consuming Probiotics and Prebiotics

Gut microbiota is a group of microorganisms that are deposited throughout the entire gastrointestinal tract. Currently, thanks to genomic tools, studies of gut microbiota have pointed towards the understanding of the metabolism of important bacteria that are not cultivable and their relationship with human homeostasis. Alterations in the composition of gut microbiota could explain, at least in part, some epidemics, such as diabetes and obesity. Likewise, dysbiosis has been associated with gastrointestinal disorders, neurodegenerative diseases, and even cancer. That is why several studies have recently been focused on the direct relationship that these types of conditions have with the specific composition of gut microbiota, as in the case of the microbiota-intestine-brain axis. In the same way, the control of microbiota is related to the diet. Therefore, this review highlights the importance of gut microbiota, from its composition to its relationship with the human health-disease condition, as well as emphasizes the effect of probiotic and prebiotic consumption on the balance of its composition.

Bifidobacterium reduction is associated with high blood pressure in children with type 1 diabetes mellitus

Children with Type 1 diabetes mellitus (T1DM) have an elevated risk of abnormal blood pressure (BP) measurements and patterns. Both hypertension and T1DM are well-known risk factors for cardiovascular disease and kidney failure. The human microbiome has been linked to both diabetes and hypertension, but the relationship between the gut microbiome and BP in children with T1DM is not well-understood. In this cross-sectional study, we examined the relationship between resting office BP and gut microbiota composition, diversity, and richness in children with T1DM and healthy controls. We recruited 29 pediatric subjects and divided them into three groups: healthy controls (HC, n = 5), T1DM with normal BP (T1DM-Normo, n = 17), and T1DM with elevated BP (T1DM-HBP, n = 7). We measured the BP, dietary and clinical parameters for each subject. We collected fecal samples to perform the 16s rDNA sequencing and to measure the short-chain fatty acids (SCFAs) level. The microbiome downstream analysis included the relative abundance of microbiota, alpha and beta diversity, microbial markers using Linear Discriminant effect size analysis (LEfSe), potential gut microbial metabolic pathways using Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) and metabolic pathways validation using Statistical Inference of Associations between Microbial Communities And host phenotype (SIAMCAT) machine learning toolbox. Our study results showed that T1DM-HBP group had distinct gut microbial composition (at multiple taxonomic levels) and reduced diversity (richness and abundance) compared with T1DM-Normo and HC groups. Children with T1DM-HBP showed a significant reduction of Bifidobacterium levels (especially B. adolescentis, B. bifidum, and B. longum) compared to the T1DM-Normo group. We also observed unique gut-microbial metabolic pathways, such as elevated lipopolysaccharide synthesis and glutathione metabolism in children with T1DM-HBP compared to T1DM-Normo children. We can conclude that the reduction in the abundance of genus Bifidobacterium could play a significant role in elevating the BP in pediatric T1DM subjects. More studies are needed to corroborate our findings and further explore the potential contributing mechanisms we describe.

Sex differences in the intestinal microbiome: interactions with risk factors for atherosclerosis and cardiovascular disease

Background

There are clearly sex differences in cardiovascular disease. On average, women experience cardiovascular events at an older age, and at any age, women, on average, have less atherosclerotic plaque than men. The role of the human intestinal microbiome in health and disease has garnered significant interest in recent years, and there have been indications of sex differences in the intestinal microbiome. The purpose of this narrative review was to evaluate evidence of sex differences in the interaction between the intestinal microbiome and risk factors for cardiovascular disease. Several studies have demonstrated changes in microbiota composition and metabolic profile as a function of diet, sex hormones, and host metabolism, among other factors. This dysbiosis has consequently been associated with several disease states, including atherosclerosis and cardiovascular disease. In this respect, there is a growing appreciation for the microbiota and its secreted metabolites, including trimethylamine N-oxide (TMAO), derived from intestinal bacterial metabolic pathways involving dietary choline and l-carnitine, as novel risk factors for atherosclerosis and cardiovascular outcomes. Although traditional risk factors for vascular disease have been studied broadly over the years, there exists little research to evaluate interactions of cardiovascular risk factors with a potentially sexually dimorphic intestinal microbiome. This review evaluates the role of sex differences in the composition of the intestinal microbiome, including effects of sex hormones on the microbiome, and the effects of these sex differences on cardiovascular risk factors. Diabetes and obesity exhibit sexual dimorphism, while the data concerning hypertension and dyslipidemia remain inconclusive based on the available literature. In addition, an increased proportion of gram-negative species capable of driving metabolic endotoxemia and a low-grade inflammatory response, as well as decreased numbers of butyrate-producing species, have been observed in relation to traditional vascular risk factors. In this context, circulating SCFAs and TMAO are recognized as key metabolites of the intestinal microbiome that can be readily measured in the blood for the evaluation of metabolic profile.

Conclusion

Novel strategies focused on resolving intestinal dysbiosis as a means to slow progression of atherosclerosis and reduce the risk of cardiovascular disease should be evaluated through a lens of sex differences.

Impact of Nutritional Epigenetics in Essential Hypertension: Targeting microRNAs in the Gut-Liver Axis

PURPOSE OF REVIEW

To review the current knowledge on interactions between dietary factors and microRNAs (miRNAs) in essential hypertension (EH) pathogenesis.

RECENT FINDINGS

There exists an integration of maintenance signals generated by genetic, epigenetic, immune, and environmental (e.g., dietary) factors that work to sustain balance in the gut-liver axis. It is well established that an imbalance in this complex, intertwined system substantially increases the risk for EH. As such, pertinent research has been taken to decipher how each signal operates in isolation and together in EH progression. Recent literature indicates that both macro- and micronutrients interrupt regulatory miRNA expressions and thus, alter multiple cellular processes that contribute to EH and its comorbidities. We highlight how carbohydrates, lipids, proteins, salt, and potassium modify miRNA signatures during EH. The disruption in miRNA expression can negatively impact communication systems such as over activating the renin-angiotensin-aldosterone system, modulating the vascular smooth muscle cell phenotype, and promoting angiogenesis to favor EH. We also delineate the prognostic value of miRNAs in EH and discuss the pros and cons of surgical vs dietary prophylactic approaches in EH prevention. We propose that dietary-dependent perturbation of the miRNA profile is one mechanism within the gut-liver axis that dictates EH development.

The emerging role of gut microbiota in cardiovascular diseases

There is mounting evidence which suggests the involvement of gut microbiota dysbiosis in the pathogenesis of various cardiovascular diseases (CVD) and associated risk states such as hypertension, type 2 diabetes, obesity and dyslipidaemia, atherosclerosis, heart failure and atrial fibrillation. The current review comprehensively summarizes the various pathogenetic mechanisms of dysbiosis in these conditions and discusses the key therapeutic implications. Further deeper understanding of the pathogenetic links between CVD and gut microbiota dysbiosis can aid in the development of novel microbiota-based targets for the management of CVDs.

Effects of probiotic therapy on cardio-metabolic parameters and autonomic modulation in hypertensive women: a randomized, triple-blind, placebo-controlled trial

BACKGROUND AND AIMS

We assessed the effects of probiotic therapy for 8 weeks on cardiometabolic variables and autonomic function in women medically diagnosed with arterial hypertension.

METHODS AND RESULTS

Forty women with arterial hypertension, 20-50 years, were assigned to two groups in this randomized, triple-blind, placebo-controlled clinical trial. Patients in the probiotic group received a daily sachet containing Lactobacillus para casei LPC-37, Lactobacillus rhamnosus HN001, Lactobacillus acidophilus NCFM, and Bifidobacterium lactis HN019 (109 CFU of each strain) for 8 weeks. Patients in the placebo group received identical sachets with polydextrose (1 g day-1, for 8 weeks). Anthropometric, BP, electrocardiogram, biochemical measurements, fecal microbiota composition, and glucose hydrogen breath test were assessed at baseline and after 8 weeks intervention. Anthropometric variables (weight, BMI, and waist circumference) were similar between the two groups (p > 0.05). Probiotic supplementation significantly reduced fasting glucose (change -10.3 mg dL-1, p < 0.05) and cholesterol levels (change -23.6 mg dL-1, p < 0.05), and increased the HDL-cholesterol (change 6.5 mg dL-1, p < 0.05) compared with the baseline condition. Probiotic supplementation lowered, although without statistical significance, systolic BP by about 5 mmHg and diastolic BP by about 2 mmHg in hypertensive women. Lastly, probiotic administration reduced the low frequency (LF) oscillation and LF/high frequency (HF) ratio (p < 0.05) in the frequency domain of heart rate variability, suggesting an improvement in autonomic modulation.

CONCLUSION

Probiotic therapy for 8 weeks reduced fasting glucose levels, and improved the lipid profile and autonomic modulation in hypertensive women.

Could the Gut Microbiota Serve as a Therapeutic Target in Ischemic Stroke?

The brain-gut axis is a relatively recent discovery of a two-way regulation system between the gut and brain, suggesting that the gut microbiota may be a promising targeted prevention and treatment strategy for patients with a high risk of acute cerebral ischemia/reperfusion injury. There are many risk factors for ischemic stroke, and many studies have shown that the gut microbiota affects the absorption and metabolism of the body, as well as the risk factors of stroke, such as blood pressure, blood glucose, blood lipids, and atherosclerosis, either directly or indirectly. Furthermore, the gut microbiota can affect the occurrence and prognosis of ischemic stroke by regulating risk factors or immune responses. Therefore, this study aimed to collect evidence of the interaction between gut microbiota and ischemic stroke, summarize the interaction mechanism between the two, and explore the gut microbiota as a new targeted prevention and treatment strategy for patients with high ischemic risk.

Invited review: Effect of antihypertensive fermented milks on gut microbiota

Hypertension is a risk factor for the development of other cardiovascular diseases and remains one of the leading causes of death worldwide. Although genetic and environmental factors are associated with the development of hypertension, it has been recently recognized that gut microbiota (GM) may also have an effect on human health. In this sense, gut dysbiosis (a marked decrease in richness and diversity of GM) has been linked to different metabolic diseases, such as hypertension. Therefore, different studies have been pursued to reduce gut dysbiosis and diminish hypertension. Different strategies to maintain a balanced GM, particularly through diet and the use of probiotics, are being evaluated. Most recently, the effect of antihypertensive fermented milks on GM has been addressed. New evidence suggests that antihypertensive fermented milks may modulate GM. Thus, the aim of this review is to present available information related to the effect of antihypertensive fermented milks on gut microbiota.

The effect of probiotic fermented milk products on blood lipid concentrations: A systematic review and meta-analysis of randomized controlled trials

AIM

Fermented milk products are suggested as a supplementary therapy to help reduce blood lipid levels. However, the results of clinical studies are conflicting.

DATA SYNTHESIS

This study systematically reviewed 39 randomized controlled trials (n = 2237 participants) to investigate the effect of probiotic fermented milk products on blood lipids. A meta-analysis was performed using random effects models, with weighted mean differences (WMDs) and 95% confidence interval (CI). Statistically significant reductions in blood low-density lipoprotein cholesterol (LDL-C) (WMD: -7.34 mg/dL, 95% CI: from -10.04 to -4.65, and P < 0.001) and total cholesterol (TC) concentrations (WMD: -8.30 mg/dL, 95% CI: from -11.42 to -5.18, and P < 0.001) were observed. No statistically significant effect of probiotic fermented milk was observed on blood high-density lipoprotein cholesterol (HDL-C) and triacylglycerol (TAG) levels. The effect on TC and LDL-C level was more pronounced in men, and a greater reduction in TAG was observed in trials with longer interventions (≥8 weeks) as compared to their counterparts.

CONCLUSIONS

Available evidence suggests that probiotic fermented milk products may help to reduce serum TC and LDL-C cholesterol levels, particularly in men and when they are consumed for ≥8 weeks.

The Role and Mechanism of Intestinal Flora in Blood Pressure Regulation and Hypertension Development

Significance: Hypertension (HTN) has a complex etiology that is characterized by genetic and environmental factors. It has become a global health burden leading to cardiovascular diseases and kidney diseases, ultimately progressing to premature death. Accumulating evidence indicated that gut microbiome was associated with metabolic disorders and inflammation, which were closely linked to HTN. Recent Advances: Recent studies using bacterial genomic analysis and fecal microbiota transplantation as well as many lines of seminal evidence demonstrated that aberrant gut microbiome was significantly associated with HTN. The intestinal microbiome of both patients and animals with HTN had decreased bacterial diversity, disordered microbial structure and functions, and altered end products of fermentation. Gut dysbiosis and metabolites of the gut microbiota play an important role in blood pressure (BP) control, and they are therefore responsible for developing HTN. Critical Issues: This study aimed at focusing on the recent advances in understanding the role played by gut bacteria and the mechanisms underlying the pathological milieu that induced elevated BP and led to HTN pathogenesis. Potential intervention strategies targeting the correction of gut dysbiosis to improve HTN development were summarized. Future Directions: Larger numbers of fecal transplants from participants with HTN should be carried out to examine the magnitude of BP changes with the replacement of the gut microbiome. The proposed mechanisms for the gut in regulating BP remain to be verified. Whether intervention strategies using probiotics, dietary interventions, bacteriophages, and fecal transplants are feasible for individuals with HTN remains to be explored. Antioxid. Redox Signal. 34, 811-830.

Haematological, biochemical, enzymological and histological responses of Labeo rohita exposed to methyl orange dye solution treated with Oedogonium subplagiostomum AP1

The present investigation is an attempt to assess the impact of untreated methyl orange and Oedogonium subplagiostomum AP1 treated methyl orange dye solutions on Labeo rohita. The behavioural response, mortality, haematological (red blood corpuscles (RBC), packed cell volume (PCV), haemoglobin (Hb), white blood corpuscles (WBC), mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH) and mean corpuscular haemoglobin concentration (MCHC)), biochemical (plasma glucose and protein), enzymological (aspartate amino transaminases (AST) and alanine amino transaminases (ALT)) and histological examination (gills, liver and kidney) of Labeo rohita are exposed to untreated and treated methyl orange dye solutions were assessed on 7th day. The fish exposed to tap water and treated dye solution showed normal behavioural response whereas abnormal behaviour was noted in fish exposed to untreated dye solution. Similar trend was recorded in the mortality rate of the fishes. Fish exposed to untreated dye solution showed reduction in RBC, PCV, Hb, MCHC, plasma glucose and plasma protein, increased level of WBC, MCV and MCH and also alteration in AST and ALT thereby indicating the toxicity of the dye. No such reduction and alteration were observed in haematological, biochemical and enzymological levels of fishes exposed to tap water and treated dye solution indicating the non-toxic nature of the degraded metabolites of dye. Histological examination of fishes exposed to methyl orange dye revealed necrosis and haemorrhage in the gills and hepatocytes, congested and shrunken glomeruli in kidney thereby indicating the toxicity of the dye. The histoarchitecture of control and algae-treated fishes showed no structural changes indicating the non-toxic nature of the degraded metabolites of the dye. The results concluded that methyl orange dye solution treated with O. subplagiostomum AP1 can be explored for aquacultural purposes owing to its non-toxic nature.

The Gut Microbiome in Hypertension: Recent Advances and Future Perspectives

The pathogenesis of hypertension is known to involve a diverse range of contributing factors including genetic, environmental, hormonal, hemodynamic and inflammatory forces, to name a few. There is mounting evidence to suggest that the gut microbiome plays an important role in the development and pathogenesis of hypertension. The gastrointestinal tract, which houses the largest compartment of immune cells in the body, represents the intersection of the environment and the host. Accordingly, lifestyle factors shape and are modulated by the microbiome, modifying the risk for hypertensive disease. One well-studied example is the consumption of dietary fibers, which leads to the production of short-chain fatty acids and can contribute to the expansion of anti-inflammatory immune cells, consequently protecting against the progression of hypertension. Dietary interventions such as fasting have also been shown to impact hypertension via the microbiome. Studying the microbiome in hypertensive disease presents a variety of unique challenges to the use of traditional model systems. Integrating microbiome considerations into preclinical research is crucial, and novel strategies to account for reciprocal host-microbiome interactions, such as the wildling mouse model, may provide new opportunities for translation. The intricacies of the role of the microbiome in hypertensive disease is a matter of ongoing research, and there are several technical considerations which should be accounted for moving forward. In this review we provide insights into the host-microbiome interaction and summarize the evidence of its importance in the regulation of blood pressure. Additionally, we provide recommendations for ongoing and future research, such that important insights from the microbiome field at large can be readily integrated in the context of hypertension.

Gut Dysbiosis and Western Diet in the Pathogenesis of Essential Arterial Hypertension: A Narrative Review

Metabolic syndrome is a cluster of the most dangerous cardiovascular (CV) risk factors including visceral obesity, insulin resistance, hyperglycemia, alterations in lipid metabolism and arterial hypertension (AH). In particular, AH plays a key role in the complications associated with metabolic syndrome. High salt intake is a well-known risk factor for AH and CV diseases. Vasoconstriction, impaired vasodilation, extracellular volume expansion, inflammation, and an increased sympathetic nervous system (SNS) activity are the mechanisms involved in the pathogenesis of AH, induced by Western diet. Gut dysbiosis in AH is associated with reduction of short chain fatty acid-producing bacteria: acetate, butyrate and propionate, which activate different pathways, causing vasoconstriction, impaired vasodilation, salt and water retention and a consequent high blood pressure. Moreover, increased trimethylamine N-oxide and lipopolysaccharides trigger chronic inflammation, which contributes to endothelial dysfunction and target organs damage. Additionally, a high salt-intake diet impacts negatively on gut microbiota composition. A bidirectional neuronal pathway determines the “brain–gut” axis, which, in turn, influences blood pressure levels. Then, we discuss the possible adjuvant novel treatments related to gut microbiota modulation for AH control.

Microbiota and Metabolites as Factors Influencing Blood Pressure Regulation

The study of microbes has rapidly expanded in recent years due to a surge in our understanding that humans host a plethora of commensal microbes, which reside in their bodies and depending upon their composition, contribute to either normal physiology or pathophysiology. This article provides a general foundation for learning about host-commensal microbial interactions as an emerging area of research. The article is divided into two sections. The first section is dedicated to introducing commensal microbiota and its known effects on the host. The second section is on metabolites, which are biochemicals that the host and the microbes use for bi-directional communication with each other. Together, the sections review what is known about how microbes interact with the host to impact cardiovascular physiology, especially blood pressure regulation. © 2021 American Physiological Society. Compr Physiol 11:1731-1757, 2021.

The beneficial effects of cinnamon among patients with metabolic diseases: A systematic review and dose-response meta-analysis of randomized-controlled trials

This systematic review and meta-analysis aims to summarize and conclude the clinical evidence regarding the use of cinnamon among patients with metabolic diseases. A comprehensive literature search without any limitation on language was conducted using the following bibliographical databases: ISI Web of Science, Embase, Scopus, PubMed, and Google Scholar. Search was conducted up to 23 January 2020. A total of 35 clinical trials were included for final analysis. Pooling of results showed a significant reducing effect of cinnamon on total cholesterol (TC) (weighted mean difference (WMD) = -11.67 mg/dL; P = 0.010), triglyceride (TG) (WMD = -16.27 mg/dL; P < 0.001), low density lipoprotein-cholesterol (LDL-C) (WMD = -6.36 mg/dL; P < 0.001), serum glucose (WMD = -11.39 mg/dL; P < 0.001), serum insulin (WMD = -1.27 μIU/mL; P = 0.028), and waist circumstance (WC) (WMD = -1.68 cm; P = 0.016). These lowering effects on TG, TC, LDL-C, and serum glucose levels were robust in studies that used cinnamon supplementation dose ≤1.5 g. Also, our findings of the present meta-analysis showed that cinnamon supplementation could have favorable effects on high density lipoprotein-cholesterol (HDL-C, WMD = 1.35; P = 0.038) as well as systolic (WMD = -3.95 mmHg; P = 0.018) and diastolic (WMD = -3.36; P = 0.001) blood pressure among patients with metabolic diseases. The present meta-analysis suggests that cinnamon might exert beneficial effects on various cardiometabolic risk factors among patients with metabolic diseases.

Integrated metagenome and metabolome analyses of blood pressure studies in early postmenopausal Chinese women

OBJECTIVE

We carried out sensitivity analyses on gut microbiota metagenomic sequencing, untargeted metabolome, targeted metabolome for short-chain fatty acids (SCFAs) and human whole genome sequencing from 402 early postmenopausal Chinese women to search for early omics-biomarkers and gain novel insights into the potential mechanisms of BP regulation in postmenopausal women.

METHODS

Clusters of co-abundant gut bacterial species and serum untargeted metabolites were identified by weighted gene co-expression network analysis (WGCNA). Partial least square analysis and joint analysis were performed to detect BP-associated omics-variables. Partial Pearson correlation was conducted to identify the interactions of microbe--host for host BP variation. Mendelian randomization analysis and causal inference test were used to examine causal relationships among gut microbiota, metabolites and BP variation.

RESULTS

In the present study, 651 bacterial species and 296 metabolites were binned into 53 and 26 co-abundance clusters by WGCNA, respectively. Then, we totally identified four gut bacterial species, one host metabolites and two SCFAs that were significantly associated with both SBP and DBP. Moreover, we found that gut microbiota would play important roles in host metabolic activity. Finally, our results revealed that increased Bacteroides fragilis could elevate BP via decreased caproic acid, and phenylacetylglutamine mediated the causal relationships of both B. fragilis and Clostridium sp.CAG.226 on DBP variation.

CONCLUSION

Multi-omics datasets integration has the potential to capture complementary effect and their interactions for BP variation, revealed the potential pathogenesis of BP variation and may be useful for studying other complex diseases/traits.

Nutraceuticals and blood pressure control: a European Society of Hypertension position document

: High-normal blood pressure (BP) is associated with an increased risk of cardiovascular disease, however the cost-benefit ratio of the use of antihypertensive treatment in these patients is not yet clear. Some dietary components and natural products seems to be able to significantly lower BP without significant side effects. The aim of this position document is to highlight which of these products have the most clinically significant antihypertensive action and wheter they could be suggested to patients with high-normal BP. Among foods, beetroot juice has the most covincing evidence of antihypertensive effect. Antioxidant-rich beverages (teas, coffee) could be considered. Among nutrients, magnesium, potassium and vitamin C supplements could improve BP. Among nonnutrient-nutraceuticals, soy isoflavones could be suggested in perimenopausal women, resveratrol in insulin-resistant patients, melatonin in study participants with night hypertension. In any case, the nutracutical approach has never to substitute the drug treatment, when needed.

TMA/TMAO in Hypertension: Novel Horizons and Potential Therapies

Hypertension is the most prevalent chronic disease and a risk factor for various diseases. Although its mechanisms and therapies are constantly being updated and developed, they are still not fully clarified. In recent years, novel gut microbiota and its metabolites have attracted widespread attention. It is strongly linked with physiological and pathological systems, especially TMA and TMAO. TMA is formed by intestinal microbial metabolism of choline and L-carnitine and converted into TMAO by FMO3. This paper collected and collated the latest researches and mainly discussed the following four parts. It introduced gut microbiota; provided a focus on TMA, TMA-producing bacteria, and TMAO; summarized the alternations in hypertensive patients and animals; discussed the mechanisms of TMAO with two respects; and summarized the regulatory factors may be as new interventions and therapies of hypertension. And, more relevant studies are still prospected to be accomplished between hypertension and TMA/TMAO for further clinical services.

Gut Microbiome over a Lifetime and the Association with Hypertension

PURPOSE OF REVIEW

Microorganisms living within an ecosystem create microbial communities and play key roles in ecosystem functioning. During their lifespan, humans share their bodies with a variety of microorganisms. More than 10-100 trillion symbiotic microorganisms live on and within human beings, and the majority of these microorganisms populate the distal ileum and colon (referred to as the gut microbiota). Interactions between the gut microbiota and the host involve signaling via chemical neurotransmitters and metabolites, neuronal pathways, and the immune system. Hypertension is a complex and heterogeneous pathophenotype. A reductionist approach that assumes that all patients who have the same signs of a disease share a common disease mechanism and thus should be treated similarly is insufficient for optimal blood pressure management. Herein, we have highlighted the contribution of the gut microbiome to blood pressure regulation in humans.

RECENT FINDINGS

Gut dysbiosis-an imbalance in the composition and function of the gut microbiota-has been shown to be associated with hypertension. Gut dysbiosis occurs via environmental pressures, including caesarean section, antibiotic use, dietary changes, and lifestyle changes over a lifetime. This review highlights how gut dysbiosis may affect a host's blood pressure over a lifetime. The review also clarifies future challenges in studies of associations between the gut microbiome and hypertension.

Impact of functional foods and nutraceuticals on high blood pressure with a special focus on meta-analysis: review from a public health perspective

In recent times many researchers are expressing immense interest in nutraceuticals and functional foods for combating various diseases or abnormal conditions, especially against hypertension (HT). Persistent HT is medically referred to as chronic high blood pressure (BP) and considered to be one of the major risk factors for the deadliest diseases including cardiovascular disease (CVD) and cerebrovascular diseases. Hence HT poses a serious socio-economic burden worldwide, particularly to developing countries. The current treatment strategy for HT includes standard anti-hypertensive drugs, which are associated with many adverse effects and lower drug adherence rates. Therefore, an alternative or complementary natural therapy (functional foods or nutraceuticals or dietary supplements) would be the alternate choice along with a modified lifestyle pattern that might help to manage or combat HT and its related complications. During this review, the author would like to shed light on the basic science behind HT including pathophysiology and the impact of dietary salt on HT and the impact of various functional foods or nutraceuticals against HT in humans (meta-analysis and systemic review). This contribution gives a better idea (public health perspective) for choosing the best functional foods/nutraceuticals for the prevention, management or delaying the onset of HT and its associated conditions along with modified lifestyle patterns and standard anti-hypertensive drugs.

New Insights into Stroke Prevention and Treatment: Gut Microbiome

Stroke, a lethal neurological disease, accounts for a grave economic burden on society. Despite extensive basic and clinical studies on stroke prevention, a precise effective treatment approach for stroke at this stage remains unavailable. The majority of our body's gut microbiota plays a vital role in food digestion, immune regulation, and nervous system development, which is highly associated with the development of some diseases. Multiple clinical studies have documented variation in the composition of gut microbiota between stroke patients and healthy counterparts. Moreover, the intervention of intestinal symbiotic microorganisms via several mechanisms plays an active role in stroke prognosis. In the prevention and treatment of stroke, the gut microbiota gives off a seductive glow, this is a promising therapeutic target. This paper summarizes the current knowledge of stroke and gut microbiota, and systematically describes the possible mechanisms of interaction between stroke and gut microbiota, the relationship between stroke-related risk factors and gut microbiota, and the treatment of gut flora using microorganisms. Thus, it could valuably elucidate the correlation of gut microbiota with stroke incidence, providing stroke researchers with a new strategy for stroke prevention and treatment by regulating gut microbiota.

Efficacy of synbiotic interventions on blood pressure: a systematic review and meta-analysis of clinical trials

PURPOSE

The present systematic review and meta-analysis aimed to evaluate the effect of synbiotic interventions on blood pressure levels in adults.

METHODS

A systematic literature search was conducted in the databases of MEDLINE, Scopus, Web of Science, and Cochrane through March 2020 to identify all randomized control trials (RCTs) investigating the effects of synbiotic interventions on blood pressure parameter, including systolic (SBP) and diastolic blood pressure (DBP). Grading of Recommendations Assessment, Development and Evaluation (GRADE) scale was used to assess the certainty of evaluated outcomes and determine the strength of recommendations.

RESULTS

Eleven RCTs were included in the meta-analysis. Synbiotic interventions significantly reduced SBP (-3.02 mmHg; 95% CI: -4.84, -1.21; I² = 55%) without changing DBP levels (-0.57 mmHg; 95% CI: -1.78, 0.64; I² = 50%). Subgroup analyses revealed that the SBP-lowering effects of synbiotic interventions were more pronounced wherein trials were longer (≥12 weeks), synbiotic interventions were administrated as a supplement, and participants were younger (<50 years old). Also, a significant improvement in both SBP and DBP levels was evident in subgroups with a lower (<30 kg/m²) body mass index.

CONCLUSIONS

Synbiotic interventions may significantly improve SBP levels in adults.

Innate Immune Cells and Hypertension: Neutrophils and Neutrophil Extracellular Traps (NETs)

Uncontrolled immune system activation amplifies end-organ injury in hypertension. Nonetheless, the exact mechanisms initiating this exacerbated inflammatory response, thereby contributing to further increases in blood pressure (BP), are still being revealed. While participation of lymphoid-derived immune cells has been well described in the hypertension literature, the mechanisms by which myeloid-derived innate immune cells contribute to T cell activation, and subsequent BP elevation, remains an active area of investigation. In this article, we critically analyze the literature to understand how monocytes, macrophages, dendritic cells, and polymorphonuclear leukocytes, including mast cells, eosinophils, basophils, and neutrophils, contribute to hypertension and hypertension-associated end-organ injury. The most abundant leukocytes, neutrophils, are indisputably increased in hypertension. However, it is unknown how (and why) they switch from critical first responders of the innate immune system, and homeostatic regulators of BP, to tissue-damaging, pro-hypertensive mediators. We propose that myeloperoxidase-derived pro-oxidants, neutrophil elastase, neutrophil extracellular traps (NETs), and interactions with other innate and adaptive immune cells are novel mechanisms that could contribute to the inflammatory cascade in hypertension. We further posit that the gut microbiota serves as a set point for neutropoiesis and their function. Finally, given that hypertension appears to be a key risk factor for morbidity and mortality in COVID-19 patients, we put forth evidence that neutrophils and NETs cause cardiovascular injury post-coronavirus infection, and thus may be proposed as an intriguing therapeutic target for high-risk individuals. © 2021 American Physiological Society. Compr Physiol 11:1575-1589, 2021.

Link between microbiota and hypertension: Focus on LPS/TLR4 pathway in endothelial dysfunction and vascular inflammation, and therapeutic implication of probiotics

High blood pressure (BP) presents a significant public health challenge. Recent findings suggest that altered microbiota can exert a hypertensive effect on the host. One of the possible mechanisms involved is the chronic translocation of its components, mainly lipopolysaccharides (LPS) into systemic circulation leading to metabolic endotoxemia. In animal models, LPS has been commonly used to induce endothelial dysfunction and vascular inflammation. In human studies, plasma LPS concentration has been positively correlated with hypertension, however, the mechanistic link has not been fully elucidated. It is hypothesised here that the LPS-induced direct alterations to the vascular endothelium and resulting hypertension are possible targets for probiotic intervention. The methodology of this review involved a systematic search of the literature with critical appraisal of papers. Three tranches of search were performed: 1) existing review papers; 2) primary mechanistic animal, in vitro and human studies; and 3) primary intervention studies. A total of 70 peer-reviewed papers were included across the three tranches and critically appraised using SIGN50 for human studies and the ARRIVE guidelines for animal studies. The extracted information was coded into key themes and summarized in a narrative analysis. Results highlight the role of LPS in the activation of endothelial toll-like receptor 4 (TLR4) initiating a cascade of interrelated signalling pathways including: 1) Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase/ Reactive oxygen species (ROS)/ Endothelial nitric oxide synthase (eNOS) pathway leading to endothelial dysfunction; and 2) Mitogen-Activated Protein Kinase (MAPK) and Nuclear factor kappa B (NF-κB) pathways leading to vascular inflammation. Findings from animal intervention studies suggest an improvement in vasorelaxation, vascular inflammation and hypertension following probiotic supplementation, which was mediated by downregulation of LPS-induced pathways. Randomised controlled trials (RCTs) and systematic reviews provided some evidence for the anti-inflammatory effect of probiotics with statistically significant antihypertensive effect in clinical samples and may offer a viable intervention for the management of hypertension.

Acute effects of increased gut microbial fermentation on the hypoxic ventilatory response in humans

NEW FINDINGS

What is the central question of this study? Is there a link between gut microbial fermentation and ventilatory responsiveness to hypoxia in humans? What is the main finding and its importance? Increased gut microbial fermentation is associated with augmented ventilatory (but not haemodynamic) responses to transient hypoxia. These findings imply a capacity for gut microbiota to modulate the peripheral chemoreflex response to hypoxia in humans.

ABSTRACT

Recent animal data indicate the presence of a bidirectional link between gut microbial activity and respiratory control. Nevertheless, the presence of a similar association between gut microbiota and peripheral chemoreceptor responsiveness to hypoxia in humans has not been reported to date. Therefore, we performed a within subject, placebo-controlled study in a group of 16 healthy individuals (eight men; mean ± SD age 25.9 ± 5.2 years). Participants underwent two tests (in a random order), receiving lactulose, which stimulates gut fermentation, or placebo. Ventilatory and haemodynamic responses to transient hypoxia were evaluated before and 2 h after the test meal. The magnitude of these responses was related to the net hydrogen content in the exhaled air, reflecting gut fermentation intensity. A lactulose meal, compared to placebo, caused an increase in the minute ventilation (Hyp-VI; l/min/ S p O 2 ) and breathing rate (Hyp-BR; breaths/min/ S p O 2 ) responses to hypoxia (for Hyp-VI, mean ± SD -0.03 ± 0.059 in placebo test vs. 0.05 ± 0.116 in lactulose test, P = 0.03; for Hyp-BR, -0.015 ± 0.046 vs. 0.034 ± 0.054, P = 0.01). The magnitude of these responses was positively correlated with the lactulose-induced hydrogen excretion (for Hyp-VI, r = 0.62, P = 0.01; for Hyp-BR, r = 0.73, P = 0.001). Changes in the resting parameters during normoxia did not differ significantly between the tests. Our results demonstrate that the increased gut microbial fermentation is associated with augmented ventilatory (but not haemodynamic) responses to the transient hypoxia, which implies a capacity for gut microbiota to modulate the peripheral chemoreflex in humans.

Exercise and food supplement of vitamin C ameliorate hypertension through improvement of gut microflora in the spontaneously hypertensive rats

AIMS

Exercise and food supplement of vitamin C (VC) are beneficial to human health, especially for those who suffer from hypertension. Here we tend to explore if gut microflora is involved in the anti-hypertensive effects of exercise and VC-supplement therapies.

MATERIALS AND METHODS

With the spontaneously hypertensive rat (SHR) model, the small intestine pathology and the fecal microbiota was analyzed along with the pro- and anti-inflammatory cytokines (PICs and AICs) and reactive oxygen species (ROS) in the hypothalamus paraventricular nucleus (PVN) and intestine.

KEY FINDINGS

We found that both exercise and VC intake, individually or combined, were able to alleviate the blood pressure in the SHRs comparing to the normotensive control Wistar-kyoto (WKY) rats. The expression level of PICs in the PVN and intestine of the SHRs was down-regulated while the AICs were up-regulated after treatments, together with down-regulation of ROS in the PVN. At meantime, the gut pathology was dramatically improved in the SHRs with exercise training or VC intake. Analysis of the gut microflora revealed significant changes in their composition. Several important micro-organisms that were deficient in the SHRs were found up-regulated by the treatments, including Turicibacter and Romboutsia which are involved in the short-chain fatty acid production.

SIGNIFICANCE

Exercise training and VC intake individually can modify the gut microflora composition and improve the inflammatory state in both PVN and intestine, which contribute to their anti-hypertensive function. Combination of the two treatments enhanced their effects and worth to be considered as a non-medical aid for the hypertensive patients.

Novel insights in the relationship of gut microbiota and coronary artery diseases

Atherosclerosis is a chronic, progressive, inflammatory disease in the vasculature and is common in both coronary and peripheral arteries. Human beings harbor a complex and dynamic population of microorganisms defined as the microbiota. Importantly, alterations in the bacterial composition (dysbiosis) and the metabolic compounds produced by these bacteria have been associated with the pathogenesis of many inflammatory diseases and infections. There is also a close relationship between intestinal microbiota and cardiovascular diseases. The aim of this review was to analyze how changes in the gut microbiota and their metabolites might affect coronary artery diseases. The most representative groups of bacteria that make up the intestinal microbiota are altered in coronary artery disease patients, resulting in a decrease in Bacteroidetes and an increase in Firmicutes. In relation to metabolites, trimethylamine-N-oxide plays an important role in atherosclerosis and may act as a cardiovascular risk predictor. In addition, the use of probiotics, prebiotics, diet modulation, and fecal transplantation, which may represent alternative treatments for these diseases, is thoroughly discussed. Finally, the role of lipid-lowering treatments is also analyzed as they may affect and alter the gut microbiota and, conversely, gut microbiota diversity could be associated with resistance or sensitivity to these treatments.

Washed Microbiota Transplantation Lowers Blood Pressure in Patients With Hypertension

BACKGROUND

Although transplantation of the fecal microbiota from normotensive donors has been shown to have an antihypertensive effect in hypertensive animal models, its effect on blood pressure in patients with hypertension is unclear. This study aimed to assess the effect of washed microbiota transplantation (WMT) from normotensive donors on blood pressure regulation in hypertensive patients.

METHODS

The clinical data of consecutive patients treated with washed microbiota transplantation (WMT) were collected retrospectively. The blood pressures of hypertensive patients before and after WMT were compared. The factors influencing the antihypertensive effect of WMT in hypertensive patients and fecal microbial composition of donors and hypertensive patients were also analyzed.

RESULTS

WMT exhibited an antihypertensive effect on blood pressure: the blood pressure at hospital discharge was significantly lower than that at hospital admission (change in systolic blood pressure: -5.09 ± 15.51, P = 0.009; change in diastolic blood pressure: -7.74 ± 10.42, P < 0.001). Hypertensive patients who underwent WMT via the lower gastrointestinal tract (β = -8.308, standard error = 3.856, P = 0.036) and those not taking antihypertensive drugs (β = -8.969, standard error = 4.256, P = 0.040) had a greater decrease in systolic blood pressure, and hypertensive patients not taking antihypertensive drugs also had a greater decrease in diastolic blood pressure (β = -8.637, standard error = 2.861, P = 0.004). After WMT, the Shannon Diversity Index was higher in six of eight hypertensive patients and the microbial composition of post-WMT samples tended to be closer to that of donor samples.

CONCLUSION

WMT had a blood pressure-lowering effect in hypertensive patients, especially in those who underwent WMT via the lower gastrointestinal tract and in those not taking antihypertensive drugs. Therefore, modulation of the gut microbiota by WMT may offer a novel approach for hypertension treatment.

Effect of a probiotic on blood pressure in grade 1 hypertension (HYPRO): protocol of a randomized controlled study

Background

Arterial hypertension is a major risk factor for cardiovascular disease and leads to target organ damage including stroke, heart failure, and kidney disease. About 1.5 billion people worldwide have hypertension, and it is estimated that it causes about 8 million deaths each year. Although there are several drugs available to lower blood pressure (BP), a great proportion of treated patients does not reach recommended treatment targets. Typical antihypertensive drugs target the vessels, the kidneys, and the heart. However, our gut microbiota also influences cardiovascular health, and gut dysbiosis is associated with hypertension. In this study protocol, we investigate the potential BP-lowering effect of a probiotic in patients with grade 1 hypertension.

Methods

This study is an exploratory, randomized, double-blind, placebo-controlled, parallel-group study. One hundred ten patients with grade 1 hypertension (treated or untreated) will be randomized to either the probiotic Vivomixx® or placebo. The primary endpoint is the nocturnal systolic BP measured by ambulatory blood pressure monitoring after 8 weeks adjusted for the baseline value. The secondary endpoints are changes from baseline in nocturnal diastolic BP, antihypertensive medication, fecal microbiome composition, fecal and serum metabolome, immune cell phenotypes, glucose variability after three standardized breakfasts, and health-related quality of life (PROMIS-29). We also assess the safety profile of the intervention.

Discussion

We postulate that various administrated bacteria (Lactobacilli, Bifidobacteria, and Streptococcus thermophilus) convert dietary components into active metabolites that positively affect immune cell function. A reduction of pro-inflammatory immune cell function could promote a BP-lowering effect.

Trial registration

ClinicalTrials.gov NCT03906578. Registered on 08 April 2019

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-020-04973-0.

Intestinal barrier dysfunction as a therapeutic target for cardiovascular disease

The gut microbiome and intestinal dysfunction have emerged as potential contributors to the development of cardiovascular disease (CVD). Alterations in gut microbiome are well documented in hypertension, atherosclerosis, and heart failure and have been investigated as a therapeutic target. However, a perhaps underappreciated but related role for intestinal barrier function has become evident. Increased intestinal permeability is observed in patients and mouse models of CVD. This increased intestinal permeability can enhance systemic inflammation, alter gut immune function, and has been demonstrated as predictive of adverse cardiovascular outcomes. The goal of this review is to examine the evidence supporting a role for intestinal barrier function in cardiovascular disease and its prospect as a novel therapeutic target. We outline key studies that have investigated intestinal permeability in hypertension, coronary artery disease, atherosclerosis, heart failure, and myocardial infarction. We highlight the central mechanisms involved in the breakdown of barrier function and look at emerging evidence for restored barrier function as a contributor to promising treatment strategies such as short chain fatty acid, probiotic, and renin angiotensin system-targeted therapeutics. Recent studies of more selective targeting of the intestinal barrier to improve disease outcomes are also examined. We suggest that although current data supporting a contribution of intestinal permeability to CVD pathogenesis are largely associative, it appears to be a promising avenue for further investigation. Additional studies of the mechanisms of barrier restoration in CVD and testing of intestinal barrier-targeted compounds will be required to confirm their potential as a new class of CVD therapeutic.