Effects of Probiotics on Patients with Hypertension: a Systematic Review and Meta-analysis

Efficacy of probiotics on improvement of health outcomes in cirrhotic liver disease patients: A systematic review and meta-analysis of randomised controlled trials

Liver cirrhosis is a chronic condition of the liver and is the 14th most common cause of death around the world; yet it remains an incurable disease. Probiotics have gained significant popularity as a potential treatment option for liver cirrhosis.

METHODS

A systematic review and meta-analysis was conducted to assess the effects of probiotics on liver cirrhosis. PubMed, Scopus, Cochrane Central Register for Controlled Trials (CENTRAL) and ProQuest Dissertation and Thesis were searched from 2000 to January 2024 for studies that evaluated the effects of probiotics on a variety of outcomes of liver disease.

RESULTS

A total of 22 randomised controlled trial studies were included in the meta-analysis. Probiotics significantly decreased Gamma-glutamyl transferase (effect size: 0.307, p = 0.024, 95% CI [-0.572, -0.040]) and Aspartate aminotransferase (p = 0.013, 95% CI [-17.927, -2.128]). Significant reduction in serum ammonia levels (effect size = -1.093, p = 0.000, 95% CI [-1.764, -0.423]) and endotoxin levels (effect size = -0.961, p = 0.000, 95% CI [-1.537, -0.385]) were also found.

SUMMARY

Overall probiotics could be recommended as a potential adjunct therapy for patients with cirrhosis, as they appear to have some benefit in improving liver function, and are well tolerated with minimal adverse effects. More comprehensive research with larger sample sizes is recommended to understand more about the widespread effects of probiotic use.

Recent progresses in gut microbiome mediates obstructive sleep apnea-induced cardiovascular diseases

Obstructive sleep apnea (OSA) is a multifactorial sleep disorder with a high prevalence in the general population. OSA is associated with an increased risk of developing cardiovascular diseases (CVDs), particularly hypertension, and is linked to worse outcomes. Although the correlation between OSA and CVDs is firmly established, the mechanisms are poorly understood. Continuous positive airway pressure is primary treatment for OSA reducing cardiovascular risk effectively, while is limited by inadequate compliance. Moreover, alternative treatments for cardiovascular complications in OSA are currently not available. Recently, there has been considerable attention on the significant correlation between gut microbiome and pathophysiological changes in OSA. Furthermore, gut microbiome has a significant impact on the cardiovascular complications that arise from OSA. Nevertheless, a detailed understanding of this association is lacking. This review examines recent advancements to clarify the link between the gut microbiome, OSA, and OSA-related CVDs, with a specific focus on hypertension, and also explores potential health advantages of adjuvant therapy that targets the gut microbiome in OSA.

The effects of prebiotic, probiotic or synbiotic supplementation on overweight/obesity indicators: an umbrella review of the trials' meta-analyses

Background

There is controversial data on the effects of prebiotic, probiotic, or synbiotic supplementations on overweight/obesity indicators. Thus, we aimed to clarify this role of biotics through an umbrella review of the trials' meta-analyses.

Methods

All meta-analyses of the clinical trials conducted on the impact of biotics on overweight/obesity indicators in general populations, pregnant women, and infants published until June 2023 in PubMed, Web of Sciences, Scopus, Embase, and Cochrane Library web databases included. The meta-analysis of observational and systematic review studies without meta-analysis were excluded. We reported the results by implementing the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) flowchart. The Assessment of Multiple Systematic Reviews-2 (AMSTAR2) and Grading of Recommendations Assessment, Development, and Evaluation (GRADE) systems were used to assess the methodological quality and quality of evidence.

Results

Overall, 97 meta-analysis studies were included. Most studies were conducted on the effect of probiotics in both genders. Consumption of prebiotic: 8-66 g/day, probiotic: 104 -1.35×1015 colony-forming unit (CFU)/day, and synbiotic: 106-1.5×1011 CFU/day and 0.5-300 g/day for 2 to 104 weeks showed a favorable effect on the overweight/obesity indicators. Moreover, an inverse association was observed between biotics consumption and overweight/obesity risk in adults in most of the studies. Biotics did not show any beneficial effect on weight and body mass index (BMI) in pregnant women by 6.6×105-1010 CFU/day of probiotics during 1-25 weeks and 1×109-112.5×109 CFU/capsule of synbiotics during 4-8 weeks. The effect of biotics on weight and BMI in infants is predominantly non-significant. Prebiotics and probiotics used in infancy were from 0.15 to 0.8 g/dL and 2×106-6×109 CFU/day for 2-24 weeks, respectively.

Conclusion

It seems biotics consumption can result in favorable impacts on some anthropometric indices of overweight/obesity (body weight, BMI, waist circumference) in the general population, without any significant effects on birth weight or weight gain during pregnancy and infancy. So, it is recommended to intake the biotics as complementary medications for reducing anthropometric indices of overweight/obese adults. However, more well-designed trials are needed to elucidate the anti-obesity effects of specific strains of probiotics.

Therapeutic applications of gut microbes in cardiometabolic diseases: current state and perspectives

Cardiometabolic disease (CMD) encompasses a range of diseases such as hypertension, atherosclerosis, heart failure, obesity, and type 2 diabetes. Recent findings about CMD's interaction with gut microbiota have broadened our understanding of how diet and nutrition drive microbes to influence CMD. However, the translation of basic research into the clinic has not been smooth, and dietary nutrition and probiotic supplementation have yet to show significant evidence of the therapeutic benefits of CMD. In addition, the published reviews do not suggest the core microbiota or metabolite classes that influence CMD, and systematically elucidate the causal relationship between host disease phenotypes-microbiome. The aim of this review is to highlight the complex interaction of the gut microbiota and their metabolites with CMD progression and to further centralize and conceptualize the mechanisms of action between microbial and host disease phenotypes. We also discuss the potential of targeting modulations of gut microbes and metabolites as new targets for prevention and treatment of CMD, including the use of emerging technologies such as fecal microbiota transplantation and nanomedicine. KEY POINTS: • To highlight the complex interaction of the gut microbiota and their metabolites with CMD progression and to further centralize and conceptualize the mechanisms of action between microbial and host disease phenotypes. • We also discuss the potential of targeting modulations of gut microbes and metabolites as new targets for prevention and treatment of CMD, including the use of emerging technologies such as FMT and nanomedicine. • Our study provides insight into identification-specific microbiomes and metabolites involved in CMD, and microbial-host changes and physiological factors as disease phenotypes develop, which will help to map the microbiome individually and capture pathogenic mechanisms as a whole.

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

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

Probiotic Bacillus licheniformis ZW3 Alleviates DSS-Induced Colitis and Enhances Gut Homeostasis

Despite Bacillus species having been extensively utilized in the food industry and biocontrol as part of probiotic preparations, limited knowledge exists regarding their impact on intestinal disorders. In this study, we investigated the effect of Bacillus licheniformis ZW3 (ZW3), a potential probiotic isolated from camel feces, on dextran sulfate sodium (DSS)-induced colitis. The results showed ZW3 partially mitigated body weight loss, disease activity index (DAI), colon shortening, and suppressed immune response in colitis mice, as evidenced by the reduction in the levels of the inflammatory markers IL-1β, TNF-α, and IL-6 (p < 0.05). ZW3 was found to ameliorate DSS-induced dysfunction of the colonic barrier by enhancing mucin 2 (MUC2), zonula occluden-1 (ZO-1), and occludin. Furthermore, enriched beneficial bacteria Lachnospiraceae_NK4A136_group and decreased harmful bacteria Escherichia-Shigella revealed that ZW3 improved the imbalanced gut microbiota. Abnormally elevated uric acid levels in colitis were further normalized upon ZW3 supplementation. Overall, this study emphasized the protective effects of ZW3 in colitis mice as well as some potential applications in the management of inflammation-related diseases.

Effect of daily ingestion of Bifidobacterium and dietary fiber on vascular endothelial function: a randomized, double-blind, placebo-controlled, parallel-group comparison study

Bifidobacterium animalis subsp. lactis GCL2505 (GCL2505) improves the intestinal microbiota and reduces human visceral fat. This randomized, double-blind, placebo-controlled, parallel-group study was conducted to examine the effects of inulin, a prebiotic dietary fiber, and GCL2505 on vascular endothelial function in healthy subjects (n = 60). The test drink contained 2.0 g/100 g inulin and 1.0 × 1010 colony-forming units/100 g GCL2505 and was consumed daily for 12 weeks. Flow-mediated dilation was set as the primary endpoint. Subgroup analysis of vascular endothelial function demonstrated a significant increase in the change of flow-mediated dilation (%) from weeks 0 to 12 in the GCL2505 and inulin group (n = 24) compared with the placebo group (n = 23), while an improving trend in low-density lipoprotein cholesterol and plasminogen activator inhibitor-1 were confirmed. Our results indicated that the test drink had a positive effect on vascular endothelial function and related blood parameters.

Gut Microbiota and Cardiovascular Disease: Evidence on the Metabolic and Inflammatory Background of a Complex Relationship

Several studies in recent years have demonstrated that gut microbiota-host interactions play an important role in human health and disease, including inflammatory and cardiovascular diseases. Dysbiosis has been linked to not only well-known inflammatory diseases, such as inflammatory bowel diseases, rheumatoid arthritis, and systemic lupus erythematous, but also to cardiovascular risk factors, such as atherosclerosis, hypertension, heart failure, chronic kidney disease, obesity, and type 2 diabetes mellitus. The ways the microbiota is involved in modulating cardiovascular risk are multiple and not only related to inflammatory mechanisms. Indeed, human and the gut microbiome cooperate as a metabolically active superorganism, and this affects host physiology through metabolic pathways. In turn, congestion of the splanchnic circulation associated with heart failure, edema of the intestinal wall, and altered function and permeability of the intestinal barrier result in the translocation of bacteria and their products into the systemic circulation, further enhancing the pro-inflammatory conditions underlying cardiovascular disorders. The aim of the present review is to describe the complex interplay between gut microbiota, its metabolites, and the development and evolution of cardiovascular diseases. We also discuss the possible interventions intended to modulate the gut microbiota to reduce cardiovascular risk.

Positive Health Outcomes Associated with Live Microbe Intake from Foods, Including Fermented Foods, Assessed using the NHANES Database

BACKGROUND

Live dietary microbes have been hypothesized to contribute to human health but direct evidence is lacking.

OBJECTIVES

This study aimed to determine whether the dietary consumption of live microbes is linked to improved health outcomes.

METHODS

Data from the NHANES 2001-2018 were used to assess microbial intake and their adjusted associations with selected physiological parameters (e.g., blood pressure, anthropometric measures, and biomarkers) among adults aged 19 y and older. Regression models were constructed to assess the microbial intake with each physiological parameter and adjusted for demographics and other covariates. Microbial intake was assessed as both a continuous variable and a 3-level categorical variable. Fermented foods were assessed in a separate model.

RESULTS

In continuous models, an additional 100-g intake of microbe-containing foods was associated with a lower systolic blood pressure (regression coefficient: -0.331; 95% CI: -0.447, -0.215 mm Hg), C-reactive protein (-0.013; 95% CI: -0.019, -0.008 mg/dL), plasma glucose -0.347; 95% CI: -0.570, -0.124 mg/dL), plasma insulin (-0.201; 95% CI: -0.304, -0.099 μU/mL), triglyceride (-1.389; 95% CI: -2.672, -0.106 mg/dL), waist circumference (-0.554; 95% CI: -0.679, -0.428 cm), and BMI -0.217; 95% CI: -0.273, -0.160 kg/m2) levels and a higher level of high density lipoprotein cholesterols (0.432; 95% CI: 0.289, 0.574 mg/dL). Patterns were broadly similar when microbial intake was assessed categorically and when fermented foods were assessed separately.

CONCLUSIONS

To our knowledge, this study is the first to quantify, in a nationally representative data set of American adults and using stable sets of covariates in the regression models, the adjusted associations of dietary intakes of live microbes with a variety of outcomes, such as anthropometric measures, biomarkers, and blood pressure levels. Our findings suggest that foods with higher microbial concentrations are associated with modest health improvements across a range of outcomes.

Effects of probiotics supplementation on blood pressure: An umbrella meta-analysis of randomized controlled trials

AIMS

Several meta-analyses have revealed that probiotics could lower blood pressure (BP), but the findings were inconsistent. In this regard, an umbrella meta-analysis was carried out to provide a more accurate estimate of the overall impacts of probiotics supplementation on BP.

DATA SYNTHESIS

We searched the following international databases till November 2021: PubMed, Scopus, EMBASE, Web of Science, and Google Scholar. A random-effects model was applied to evaluate the effects of probiotics on BP. Sensitivity analysis was performed by using the leave-one-out method. Grading of Recommendations Assessment, Development, and Evaluation (GRADE) was used to evaluate the certainty of evidence. Pooled effect size of 14 meta-analyses with 15,494 participants indicated significant decreases in both systolic (Weighted mean difference (WMD) = -1.96 mmHg; 95% confidence interval (CI): -2.78, -1.14, p < 0.001, and standardized mean difference (SMD) = -2.62; 95% CI: -4.96, -0.28, p < 0.001) and diastolic BP (WMD = -1.28 mmHg; 95% CI: -1.76, -0.79, p < 0.001, and SMD = -0.60 mmHg; 95% CI: -1.08, -0.12, p = 0.014) following probiotics supplementation. Greater effects on SBP were revealed in trials with a mean age of >50 years and the duration of intervention ≤10 weeks. DBP was also more reduced in studies with a dosage of ≥10¹⁰ colony forming unit (CFU), and SBP was decreased in patients with hypertension or diabetes analyzing WMD.

CONCLUSION

The present umbrella meta-analysis suggests probiotics supplementation to improve BP and claims that probiotics could be used as a complementary therapy for controlling high BP.

PROSPERO ID

CRD42022306560.

Long-term use of probiotics for the management of office and ambulatory blood pressure: A systematic review and meta-analysis of randomized, controlled trials

Previous studies showed a controversial result on the relationship between probiotics treatment duration and blood pressure (BP). The present meta-analysis is performed to summarize the effects of long-term (≥8 weeks) use of probiotics on office and ambulatory BP using combined evidence from randomized, controlled trials. We searched PubMed, Embase, Cochrane library, and the ClinicalTrials.gov till January, 2021 to identify eligible articles. Primary outcomes were changes in office BP. In the presence of heterogeneity, a random-effects model was used to calculate the combined treatment effect. Begg's funnel plots and Egger's regression test were used to assess the publication bias. Meta-analysis of 26 trials in 1624 participants demonstrated that probiotic consumption significantly decreased office systolic BP by 2.18 mmHg (95% confidence interval [CI], -3.41 to -0.94 mmHg) and diastolic BP by 1.07 mmHg (95% CI, -1.72 to -0.41 mmHg). The analysis on ambulatory BP from three trials showed a similar reduction by -2.35/-1.61 mmHg (p ≤ .052). Subgroup analysis in hypertensive and diabetic patients showed a significant reduction in systolic and diastolic BP (p ≤ .02). The reductions in diabetic and hypertensive patients were comparatively larger than nondiabetic and normotensive patients (p ≥ .052). With the increase of age, baseline body mass index (BMI), treatment duration, and systolic BP, the effects of probiotics on BP did not increase significantly (p trend ≥ .18). The present meta-analysis suggests a beneficial effect of probiotics on BP by a modest degree, especially in the diabetes mellitus and hypertension. Prolonging the treatment duration could not improve the antihypertensive effect.

Limosilactobacillus fermentum prevents gut-kidney oxidative damage and the rise in blood pressure in male rat offspring exposed to a maternal high-fat diet

Oxidative stress along the gut-kidney axis is a risk factor for developing arterial hypertension in offspring from dams fed a high-fat diet. Considering the antioxidant capacity of probiotic strains, this study evaluated the effects of a daily multistrain formulation with Limosilactobacillus fermentum 139, 263, and 296 on blood pressure (BP), renal function, and oxidative stress and along the gut-kidney axis in male offspring from dams fed a high-fat high-cholesterol (HFHC) diet during pregnancy and lactation. Dams were fed a diet control or HFHC diet during pregnancy and lactation. At 100 days of age, part of the male offspring from dams fed a HFHC diet received Limosilactobacillus fermentum formulation for 4 weeks (HFHC + Lf) daily. After the 4-week intervention, BP (tail-cuff plethysmography) and urinary and biochemical variables were measured. In addition, malondialdehyde levels, enzymatic activities of superoxide dismutase, catalase, glutathione-S-transferase, and nonenzymatic antioxidant defense (thiols content) were measured in the colon and renal cortex. Male offspring from dams fed a HFHC had increased blood pressure, impaired renal function, and oxidative stress along the gut-kidney axis. Administration of Limosilactobacillus fermentum reduced systolic, diastolic, and mean blood pressure levels and alleviated renal function impairment and oxidative stress along the gut-kidney axis in male offspring from dams fed a HFHC diet. Administration of Limosilactobacillus fermentum formulation attenuated programmed hypertension in the HFHC group through oxidative stress modulation along the gut-kidney axis.

Gastrointestinal Microbiome and Multiple Health Outcomes: Umbrella Review

In recent years, there has been growing concern about the impact of the gastrointestinal microbiome on human health outcomes. To clarify the evidence for a link between the gastrointestinal microbiome and a variety of health outcomes in humans, we conducted an all-encompassing review of meta-analyses and systematic reviews that included 195 meta-analyses containing 950 unique health outcomes. The gastrointestinal microbiome is related to mortality, gastrointestinal disease, immune and metabolic outcomes, neurological and psychiatric outcomes, maternal and infant outcomes, and other outcomes. Existing interventions for intestinal microbiota (such as probiotics, fecal microbiota transplant, etc.) are generally safe and beneficial to a variety of human health outcomes, but the quality of evidence is not high, and more detailed and well-designed randomized controlled trials are necessary.

Probiotic Intervention in the Treatment of Diabetes Mellitus: A Review

Diabetes is a noncommunicable lifestyle condition that impacts millions of individuals worldwide. Diabetes is a physiological illness that affects several different organs in the human body. Several studies have found a direct relationship between gut microbiota and diabetes control. Probiotic intervention in the treatment of diabetes mellitus has been the center of focus in the current scenario. Alteration in composition and metabolic activity of gut microbiota significantly contributes to human health. However, the key mechanism of gut microbiota in the inhibition of diabetes is not fully understood. This review discusses the effect of probiotics on diabetes and the role of gut microbiota. It emphasizes on the pharmacological effects of probiotics on diabetic symptoms like glycemic response, hypercholesterolemia, hypertension, as well as gestational diabetes.

Probiotic therapy, a novel and efficient adjuvant approach to improve glycemic status: An umbrella meta-analysis

BACKGROUND

Probiotics exert several promoting effects on the glycemic status, however, the results of meta-analyses are inconsistent. we conducted an umbrella meta-analysis, across existing systematic reviews and meta-analyses of clinical trials to determine the definite effects of supplementation with probiotics on glycemic indices.

METHODS

A comprehensive systematic search of PubMed/Medline, Scopus, EMBASE, and Web of Science was carried out till August 2021. The random-effects model was employed to conduct meta-analysis. Meta-analysis studies of randomized clinical trials examining the impacts of probiotics supplementation on glycemic indices were qualified in the current umbrella meta-analysis.

RESULTS

48 articles out of 693 in the literature search qualified for inclusion in the umbrella meta-analysis. Pooled effects of probiotics on fasting plasma glucose (FPG), hemoglobin A1C (HbA1c), homeostatic model assessment for insulin resistance (HOMA-IR), and insulin levels were reported in articles 45, 21, 35, and 33, respectively. The analysis indicated a significant decrease of FPG (ES= -0.51 mg/dL; 95% CI: -0.63, -0.38, p < 0.001), HbA1c (ES = -0.32 mg/dL; 95% CI: -0.44, -0.20, p < 0.001), HOMA-IR (ES= -0.56; 95% CI: -0.66, -0.47, p < 0.001), and insulin levels (ES= -1.09 IU/mL; 95% CI: -1.37, -0.81, p = 0.006) by probiotics supplementation.

CONCLUSION

Probiotics have amending effects on FPG, HbA1c, HOMA-IR, and insulin levels. A < 8-week period of probiotic supplementation in the moderate dosages (10⁸ or 10⁹ CFU) is an efficacious approach in improving glycemic parameters. Overall, probiotics could be recommended as an adjuvant anti-hyperglycemic agent.

Maternal High-Fat Diet and Offspring Hypertension

The incidence of hypertension has increased to epidemic levels in the past decades. Increasing evidence reveals that maternal dietary habits play a crucial role in the development of hypertension in adult offspring. In humans, increased fat consumption has been considered responsible for obesity and associated diseases. Maternal diets rich in saturated fats have been widely employed in animal models to study various adverse offspring outcomes. In this review, we discussed current evidence linking maternal high-fat diet to offspring hypertension. We also provided an in-depth overview of the potential mechanisms underlying hypertension of developmental origins that are programmed by maternal high-fat intake from animal studies. Furthermore, this review also presented an overview of how reprogramming interventions can prevent maternal high-fat-diet-induced hypertension in adult offspring. Overall, recent advances in understanding mechanisms behind programming and reprogramming of maternal high-fat diet on hypertension of developmental origins might provide the answers to curtail this epidemic. Still, more research is needed to translate research findings into practice.

Probiotics: Protecting Our Health from the Gut

The gut microbiota (GM) comprises billions of microorganisms in the human gastrointestinal tract. This microbial community exerts numerous physiological functions. Prominent among these functions is the effect on host immunity through the uptake of nutrients that strengthen intestinal cells and cells involved in the immune response. The physiological functions of the GM are not limited to the gut, but bidirectional interactions between the gut microbiota and various extraintestinal organs have been identified. These interactions have been termed interorganic axes by several authors, among which the gut-brain, gut-skin, gut-lung, gut-heart, and gut-metabolism axes stand out. It has been shown that an organism is healthy or in homeostasis when the GM is in balance. However, altered GM or dysbiosis represents a critical factor in the pathogenesis of many local and systemic diseases. Therefore, probiotics intervene in this context, which, according to various published studies, allows balance to be maintained in the GM, leading to an individual's good health.

Anti-obesity properties of probiotics; a considerable medical nutrition intervention: Findings from an umbrella meta-analysis

Although several studies have indicated that consumption of probiotics is effective in the treatment of obesity, the results in this regard have yielded controversial findings. The current umbrella meta-analysis was performed to evaluate the effects of probiotics supplementation on obesity indices in adults. Scopus, PubMed, Web of Science, Embase and Google Scholar were searched for relevant studies published till November 2021. Meta-analysis was conducted using the random-effects model. Sensitivity and subgroup analyses were performed. In total, 29 meta-analyses with 14,366 participants, including 112, 78, and 38 unique trials for body mass index (BMI), body weight (BW), and waist circumference (WC), were included in the study, respectively. The findings demonstrated that the probiotics supplementation was significantly effective on decreasing of BMI (ES = -0.21; 95% CI: -0.30, -0.13, p < 0.001; I² = 83.0%, p < 0.001), BW (ES = -0.38, 95% CI: -0.60, -0.16; p < 0.001; I² = 81.8%, p < 0.001), and WC (ES = -0.60; 95% CI: -0.89, -0.31; p < 0.001; I² = 89.1%, p < 0.001). Greater effects on BW were observed when intervention duration was >8 weeks and on obese individuals. BMI was also greatly modified in participants with metabolic syndrome and when intervention duration lasted for ≥12 weeks. The methodological quality (AMSTAR2) was moderate in 83%, low in 10%, and critically low in 7% of included studies. The current umbrella meta-analysis indicated that supplementation of probiotics in adults led to a meaningful reduction in BW, BMI, and WC. Therefore, our findings strongly recommend supplementation with probiotics as a potent intervention in the management of obesity.

The Effects of Probiotics on Inflammation, Endothelial Dysfunction, and Atherosclerosis Progression: A Mechanistic Overview

INTRODUCTION

The relationship between the intestinal microbiota dysbiosis, inflammation, and cardiovascular disorders (CVDs) has become evident, based on a growing body of literature from animal models and human studies. On the other hand, probiotics are believed to have promising effects on modifying dysbiosis and protecting against CVDs.

OBJECTIVE

This narrative review provides an overview of the link between gut microbiota, inflammation, endothelial dysfunction, and atherosclerosis. The influences of probiotic supplementation on biomarkers contributing to these conditions as the primary underlying risk factors for developing CVDs are also discussed.

METHODS

An up-to-date review was performed of the available evidence from experimental studies, clinical trials, and meta-analyses, considering their challenges and limitations. It also aimed to provide mechanistic insight into the likely mechanisms of probiotics that could prevent atherosclerosis initiation and progression.

RESULTS

Probiotic supplementation seems to be associated with reduced levels of inflammation and oxidative stress biomarkers (C-reactive protein, tumour necrosis factor-α, interleukin (IL)-6, IL-12, and malondialdehyde). Further, these agents might enhance antioxidant factors (IL-10, total antioxidant status, total antioxidant capacity, glutathione, and nitric oxide). Probiotics also appear to improve intestinal barrier integrity, reduce leakage of harmful metabolites (e.g., lipopolysaccharides), inhibit pro-inflammatory signalling pathways, and possibly suppress the formation of trimethylamine/trimethylamine oxide. Probiotics have also been found to enhance endothelial function and halter thrombosis.

CONCLUSION

The current clinical evidence underlines belief that probiotics might be associated with reduced levels of inflammation biomarkers. Experimental evidence reports that the beneficial effects of probiotics seem to be mainly imposed by triggering the secretion of short-chain fatty acids and bile acids, in addition to suppressing the NF-κB signalling pathway. However, the current studies are still in their infancy and it is of high priority to design further research on the topic.

Hypertension of Developmental Origins: Consideration of Gut Microbiome in Animal Models

Hypertension is the leading cause of global disease burden. Hypertension can arise from early life. Animal models are valuable for giving cogent evidence of a causal relationship between various environmental insults in early life and the hypertension of developmental origins in later life. These insults consist of maternal malnutrition, maternal medical conditions, medication use, and exposure to environmental chemicals/toxins. There is a burgeoning body of evidence on maternal insults can shift gut microbiota, resulting in adverse offspring outcomes later in life. Emerging evidence suggests that gut microbiota dysbiosis is involved in hypertension of developmental origins, while gut microbiota-targeted therapy, if applied early, is able to help prevent hypertension in later life. This review discusses the innovative use of animal models in addressing the mechanisms behind hypertension of developmental origins. We will also highlight the application of animal models to elucidate how the gut microbiota connects with other core mechanisms, and the potential of gut microbiota-targeted therapy as a novel preventive strategy to prevent hypertension of developmental origins. These animal models have certainly enhanced our understanding of hypertension of developmental origins, closing the knowledge gap between animal models and future clinical translation.

Human microbiome and metabolic health: An overview of systematic reviews

To summarize the microbiome's role in metabolic disorders (insulin resistance, hyperglycemia, type 2 diabetes, obesity, hyperlipidemia, hypertension, nonalcoholic fatty liver disease [NAFLD], and metabolic syndrome), systematic reviews on observational or interventional studies (prebiotics/probiotics/synbiotics/transplant) were searched in MEDLINE and Embase until September 2020. The 87 selected systematic reviews included 57 meta-analyses. Methodological quality (AMSTAR2) was moderate in 62%, 12% low, and 26% critically low. Observational studies on obesity (10 reviews) reported less gut bacterial diversity with higher Fusobacterium, Lactobacillus reuteri, Bacteroides fragilis, and Staphylococcus aureus, whereas lower Methanobrevibacter, Lactobacillus plantarum, Akkermansia muciniphila, and Bifidobacterium animalis compared with nonobese. For diabetes (n = 1), the same was found for Fusobacterium and A. muciniphila, whereas higher Ruminococcus and lower Faecalibacterium, Roseburia, Bacteroides vulgatus, and several Bifidobacterium spp. For NAFLD (n = 2), lower Firmicutes, Rikenellaceae, Ruminococcaceae, whereas higher Escherichia and Lactobacillus were detected. Discriminating bacteria overlapped between metabolic disorders, those with high abundance being often involved in inflammation, whereas those with low abundance being used as probiotics. Meta-analyses (n = 54) on interventional studies reported 522 associations: 54% was statistically significant with intermediate effect size and moderate between-study heterogeneity. Meta-evidence was highest for probiotics and lowest for fecal transplant. Future avenues include better methodological quality/comparability, testing functional differences, new intervention strategies, and considerating other body habitats and kingdoms.

Probiotics in prevention and treatment of cardiovascular diseases

Increasing knowledge of the gut microbiota and its interference in human homeostasis in recent years has contributed to a better understanding of number of different interactions occurring in the gastrointestinal tract. Disruption of the microbiota is detrimental to health and contributes to the development of numerous diseases and may also be an accelerator of pathophysiological processes such as atherosclerosis. Cardiovascular diseases are the most common cause of death worldwide, so the development of new methods to support the treatment and prevention of these diseases becoms one of the priorities of modern medicine. Probiotics may constitute an important element of support in the treatment and prevention of CVD (cardiovascular diseases). A number of papers support such a statement, however, larger clinical trials are needed. Through a number of mechanisms including mitigating inflammation, sealing the intestinal epithelium, and affecting metabolism, probiotics may have a beneficial effect on general health and slow down the pathogenesis of many diseases, including those affecting the cardiovascular system. This article contains a review of current discoveries on the role of probiotics in the prevention and support of CVD treatment.

Role of the microbiota in hypertension and antihypertensive drug metabolism

Recent evidence suggests that the gut microbiota plays an important role in the development and pathogenesis of hypertension. Dysbiosis, an imbalance in the composition and function of the gut microbiota, was shown to be associated with hypertension in both animal models and humans. In this review, we provide insights into host-microbiota interactions and summarize the evidence supporting the importance of the microbiota in blood pressure (BP) regulation. Metabolites produced by the gut microbiota, especially short-chain fatty acids (SCFAs), modulate BP and vascular responses. Harmful gut-derived metabolites, such as trimethylamine N-oxide and several uremic toxins, exert proatherosclerotic, prothrombotic, and proinflammatory effects. High-salt intake alters the composition of the microbiota, and this microbial alteration contributes to the pathogenesis of salt-sensitive hypertension. In addition, the microbiota may impact the metabolism of drugs and steroid hormones in the host. The drug-metabolizing activities of the microbiota affect the pharmacokinetic parameters of antihypertensive drugs and contribute to the pathogenesis of licorice-induced pseudohyperaldosteronism. Furthermore, the oral microbiota plays a role in BP regulation by producing nitric oxide, which lowers BP via its vasodilatory effects. Thus, antihypertensive intervention strategies targeting the microbiota, such as the use of prebiotics, probiotics, and postbiotics (e.g., SCFAs), are considered new therapeutic options for the treatment of hypertension.

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.

The Neuroimmune Role of Intestinal Microbiota in the Pathogenesis of Cardiovascular Disease

Currently, a bidirectional relationship between the gut microbiota and the nervous system, which is considered as microbiota-gut-brain axis, is being actively studied. This axis is believed to be a key mechanism in the formation of somatovisceral functions in the human body. The gut microbiota determines the level of activation of the hypothalamic-pituitary system. In particular, the intestinal microbiota is an important source of neuroimmune mediators in the pathogenesis of cardiovascular disease. This review reflects the current state of publications in PubMed and Scopus databases until December 2020 on the mechanisms of formation and participation of neuroimmune mediators associated with gut microbiota in the development of cardiovascular disease.

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.

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.

Probiotics, Prebiotics and Synbiotics-A Promising Strategy in Prevention and Treatment of Cardiovascular Diseases?

Recent evidence suggests that probiotics, prebiotics and synbiotics may serve as important dietary components in the prevention (especially) and treatment of cardiovascular diseases (CVD), but the recommendations for their use are often based on brief reports and small clinical studies. This review evaluates the current literature on the correlation between CVD and probiotics, prebiotics and synbiotics. Although research on probiotics, prebiotics and synbiotics has grown exponentially in recent years, particularly regarding the effect of probiotics on CVD, their mechanisms have not been clearly defined. It has been proposed that probiotics lower cholesterol levels, and may protect against CVD, by increasing bile salt synthesis and bile acid deconjugation. Similar effects have also been observed for prebiotics and synbiotics; however, probiotics also appear to have anti-oxidative, anti-platelet and anti-inflammatory properties. Importantly, probiotics not only have demonstrated effects in vitro and in animal models, but also in humans, where supplementation with probiotics decreases the risk factors of CVD. In addition, the properties of commercial probiotics, prebiotics and synbiotics remain undetermined, and further experimental research is needed before these substances can be used in the prevention and treatment of CVD. In particular, well-designed clinical trials are required to determine the influence of probiotics on trimethylamine-N-oxide (TMAO), which is believed to be a marker of CVDs, and to clarify the long-term effects, and action, of probiotic, prebiotic and synbiotic supplementation in combination with drug therapy (for example, aspirin). However, while it cannot be unequivocally stated whether such supplementation yields benefits in the prevention and treatment of CVDs, it is important to note that clinical studies performed to date have not identified any side-effects to use.

Implication of Gut Microbiota in Cardiovascular Diseases

Emerging evidence has identified the association between gut microbiota and various diseases, including cardiovascular diseases (CVDs). Altered intestinal flora composition has been described in detail in CVDs, such as hypertension, atherosclerosis, myocardial infarction, heart failure, and arrhythmia. In contrast, the importance of fermentation metabolites, such as trimethylamine N-oxide (TMAO), short-chain fatty acids (SCFAs), and secondary bile acid (BA), has also been implicated in CVD development, prevention, treatment, and prognosis. The potential mechanisms are conventionally thought to involve immune regulation, host energy metabolism, and oxidative stress. However, numerous types of programmed cell death, including apoptosis, autophagy, pyroptosis, ferroptosis, and clockophagy, also serve as a key link in microbiome-host cross talk. In this review, we introduced and summarized the results from recent studies dealing with the relationship between gut microbiota and cardiac disorders, highlighting the role of programmed cell death. We hope to shed light on microbiota-targeted therapeutic strategies in CVD management.