Biotic Supplements for Renal Patients: A Systematic Review and Meta-Analysis

Lycibarbarspermidine L from the fruit of Lycium barbarum L. recovers intestinal barrier damage via regulating miR-195-3p

ETHNOPHARMACOLOGICAL RELEVANCE

The fruit of Lycium barbarum L. is widely employed with the traditional effect of tonic properties. According to the theory of traditional Chinese medicine, Gou Qi can be distributed in the meridian of stomach, as well as the liver and kidney, indicating its effect on the digestive system. Clinical studies found that Gou Qi enhanced gastrointestinal functions. Pharmacological research showed the extract of Lycium barbarum exhibiting a repaired effect on the intestine barrier. Lycibarbarspermidine L (LBS L), which belongs to polyamines, is separated from the fruit of Lycium barbarum. However, it is unknown whether LBS L can restore damaged intestinal barrier like other polyamines such as spermidine.

AIM OF THE STUDY

To elucidate the recovery effect of LBS L on damaged intestinal epithelium and its miRNA-related mechanism.

MATERIALS AND METHODS

IEC-6 cells were used in vitro to assess the therapeutic effect of LBS L on the injured intestine and the regulation of miR-195-3p. Spermidine (SPD) with intestinal mucosal repair effect was used as a positive control. Sprague Dawley (SD) rats were subjected to 48 h fasting to induce intestinal epithelial atrophy in vivo. To determine the therapeutic effect of LBS L on injured intestinal epithelium and explore the mechanism, the fasting model group rats were treated with LBS L (25 mg/kg) for 4 days.

RESULTS

Results in vitro showed that LBS L (10 μM) promoted cell proliferation and migration, affecting the S phase of the cell cycle. Western blot signals showed that LBS L raised the expression level of occludin. The miR-195-3p levels were decreased following LBS L treatment, which could be inversed by transfecting miR-195-3p mimic, demonstrating that LBS L inhibited miR-195-3p to improve cell growth. Results in vivo showed that LBS L could reverse the atrophic villi and inflammatory cell infiltration in the submucosa and restore miR-195-3p, occludin, and Ki67 levels in the intestine of mice in the fasting group.

CONCLUSIONS

LBS L restores injured intestinal epithelium by reducing the expression of miR-195-3p.

Exploring a Complex Interplay: Kidney-Gut Axis in Pediatric Chronic Kidney Disease

The human intestinal microbiota is a highly intricate structure with a crucial role in promoting health and preventing disease. It consists of diverse microbial communities that inhabit the gut and contribute to essential functions such as food digestion, nutrient synthesis, and immune system development. The composition and function of the gut microbiota are influenced by a variety of factors, including diet, host genetics, and environmental features. In pediatric patients, the gut microbiota is particularly dynamic and vulnerable to disruption from endogenous and exogenous factors. Recent research has focused on understanding the interaction between the gut and kidneys. In individuals with chronic kidney disease, there is often a significant disturbance in the gut microbiota. This imbalance can be attributed to factors like increased levels of harmful toxins from the gut entering the bloodstream, inflammation, and oxidative stress. This review looks at what is known about the link between a child's gut-kidney axis, how dysbiosis, or an imbalance in the microbiome, affects chronic kidney disease, and what treatments, both pharmaceutical and non-pharmaceutical, are available for this condition.

New Insights on the Role of Marinobufagenin from Bench to Bedside in Cardiovascular and Kidney Diseases

Marinobufagenin (MBG) is a member of the bufadienolide family of compounds, which are natural cardiac glycosides found in a variety of animal species, including man, which have different physiological and biochemical functions but have a common action on the inhibition of the adenosine triphosphatase sodium-potassium pump (Na+/K+-ATPase). MBG acts as an endogenous cardiotonic steroid, and in the last decade, its role as a pathogenic factor in various human diseases has emerged. In this paper, we have collated major evidence regarding the biological characteristics and functions of MBG and its implications in human pathology. This review focused on MBG involvement in chronic kidney disease, including end-stage renal disease, cardiovascular diseases, sex and gender medicine, and its actions on the nervous and immune systems. The role of MBG in pathogenesis and the development of a wide range of pathological conditions indicate that this endogenous peptide could be used in the future as a diagnostic biomarker and/or therapeutic target, opening important avenues of scientific research.

Effect on nutritional status and biomarkers of inflammation and oxidation of an oral nutritional supplement (with or without probiotics) in malnourished hemodialysis patients. A multicenter randomized clinical trial "Renacare Trial"

Background

Malnutrition in patients undergoing hemodialysis is frequent and associated with a reduction in muscular mass and strength, with an increment in biomarkers of inflammation and oxidation.

Materials and methods

Randomized, multicenter, parallel-group trial in malnourished hemodialysis patients with three groups [(1) control (C) individualized diet, (2) oral nutritional supplement-ONS- + placebo-SU- PL-, and (3) ONS + probiotics-SU-PR]; the trial was open regarding the intake of ONS or individualized diet recommendations, but double-blind for the intake of probiotics. We obtained, at baseline and after 3 and 6 months, anthropometric measurements, handgrip strength, bioelectrical impedance analysis (BIA), dietary records, and routine biochemical parameters. Inflammation and oxidation were determined using ELISA techniques (Versamax and ProcartaPlex multiplex Immunoassay). Results were analyzed by intention to treat.

Results

A total of 31 patients (11 corresponding to group C, 10 to SU-PL, and 10 to SU-PR) completed the 6-months trial. The two groups that took supplements significantly increased their protein calorie, fat (total and n-3), and fiber intake. Weight and fat-free mass (FFM) also increased significantly in the groups on supplements, both at 3 and 6 months, and dynamometry did so in the SU-PL group. At month 3, prealbumin and vitamin D were significantly increased in the SU-TOT (SU-PL + SU-PR) group. No changes were observed regarding levels of phosphorus and potassium in any of the groups. Urea increased significantly at 6 months in the SU-PL group. There were significant changes in some inflammation biomarkers in the groups on supplements during the intervention (brain-derived neurotrophic factor, bone morphogenetic protein-2, MCP-1, IL-1-beta, IL-10, IL-4, and IL-8). The total antioxidant capacity (TAC) increased significantly in the supplemented patients, with no significant changes observed in isoprostanes.

Conclusion

The specific ONS improved protein-calorie intake, nutritional status (mainly FFM), and some biomarkers of inflammation/oxidation. The addition of probiotics could have a synergistic effect with ONS in such biomarkers.

Clinical trail registration

https://clinicaltrials.gov/ct2/show/, identifier NCT03924089.

Gut microbiome studies in CKD: opportunities, pitfalls and therapeutic potential

Interest in gut microbiome dysbiosis and its potential association with the development and progression of chronic kidney disease (CKD) has increased substantially in the past 6 years. In parallel, the microbiome field has matured considerably as the importance of host-related and environmental factors is increasingly recognized. Past research output in the context of CKD insufficiently considered the myriad confounding factors that are characteristic of the disease. Gut microbiota-derived metabolites remain an interesting therapeutic target to decrease uraemic (cardio)toxicity. However, future studies on the effect of dietary and biotic interventions will require harmonization of relevant readouts to enable an in-depth understanding of the underlying beneficial mechanisms. High-quality standards throughout the entire microbiome analysis workflow are also of utmost importance to obtain reliable and reproducible results. Importantly, investigating the relative composition and abundance of gut bacteria, and their potential association with plasma uraemic toxins levels is not sufficient. As in other fields, the time has come to move towards in-depth quantitative and functional exploration of the patient's gut microbiome by relying on confounder-controlled quantitative microbial profiling, shotgun metagenomics and in vitro simulations of microorganism-microorganism and host-microorganism interactions. This step is crucial to enable the rational selection and monitoring of dietary and biotic intervention strategies that can be deployed as a personalized intervention in CKD.

Probiotics, Prebiotics, and Synbiotics for Patients on Dialysis: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

OBJECTIVE

The current systematic review and meta-analysis investigated the effects of probiotic, prebiotic, and synbiotic administration on inflammation, metabolic parameters, nutritional status, and uremic toxin in dialysis patients.

METHODS

Up to June 2021, publications were searched in Cochrane Library, PubMed, EMBASE, and Web of Science databases. The protocol was submitted to the International Prospective Register of Systematic Reviews and was approved.

RESULTS

This meta-analysis included 18 randomized controlled trials which were eligible. This meta-analysis discovered that probiotic, prebiotic, and synbiotic supplements could reduce C-reactive protein (standardized mean difference (SMD), -0.38; 95% confidence interval (CI), -0.68 to -0.08; P = .01), interleukin 6 (SMD, -0.48; 95% CI, -0.76 to -0.20; P = .00), and indoxyl sulfate (SMD, -0.24; 95% CI, -0.48 to -0.01; P = .045) and increase high-density lipoprotein cholesterol (SMD, 0.25; 95% CI, 0.03 to 0.46; P = .025) compared with the control group but had no significant influence on tumor necrosis factor α, albumin, hemoglobin, triglyceride, total cholesterol, low-density lipoprotein cholesterol, calcium, phosphorus, uric acid, or p-cresyl sulfate in dialysis patients.

CONCLUSIONS

Probiotic, prebiotic, and synbiotic administration could reduce C-reactive protein, interleukin 6, and indoxyl sulfate and increase high-density lipoprotein cholesterol in dialysis patients. To better examine the impact, large-scale, long-term, controlled diets and well-designed randomized controlled trials are needed.

Microbial-Derived Tryptophan Catabolites, Kidney Disease and Gut Inflammation

Uremic metabolites, molecules either produced by the host or from the microbiota population existing in the gastrointestinal tract that gets excreted by the kidneys into urine, have significant effects on both health and disease. Tryptophan-derived catabolites are an important group of bacteria-produced metabolites with an extensive contribution to intestinal health and, eventually, chronic kidney disease (CKD) progression. The end-metabolite, indoxyl sulfate, is a key contributor to the exacerbation of CKD via the induction of an inflammatory state and oxidative stress affecting various organ systems. Contrastingly, other tryptophan catabolites positively contribute to maintaining intestinal homeostasis and preventing intestinal inflammation—activities signaled through nuclear receptors in particular—the aryl hydrocarbon receptor (AhR) and the pregnane X receptor (PXR). This review discusses the origins of these catabolites, their effect on organ systems, and how these can be manipulated therapeutically in the future as a strategy to treat CKD progression and gut inflammation management. Furthermore, the use of biotics (prebiotics, probiotics, synbiotics) as a means to increase the presence of beneficial short-chain fatty acids (SCFAs) to achieve intestinal homeostasis is discussed.

Short-Chain Fatty Acids in Chronic Kidney Disease: Focus on Inflammation and Oxidative Stress Regulation

Chronic Kidney Disease (CKD) is a debilitating disease associated with several secondary complications that increase comorbidity and mortality. In patients with CKD, there is a significant qualitative and quantitative alteration in the gut microbiota, which, consequently, also leads to reduced production of beneficial bacterial metabolites, such as short-chain fatty acids. Evidence supports the beneficial effects of short-chain fatty acids in modulating inflammation and oxidative stress, which are implicated in CKD pathogenesis and progression. Therefore, this review will provide an overview of the current knowledge, based on pre-clinical and clinical evidence, on the effect of SCFAs on CKD-associated inflammation and oxidative stress.

Probiotic Intake and Inflammation in Patients With Chronic Kidney Disease: An Analysis of the CKD-REIN Cohort

Background and Aims

Little is known about the effects of probiotics on inflammation in the context of chronic kidney disease (CKD). We investigated the association between probiotic intake and inflammation in patients with moderate-to-advanced CKD.

Methods

We performed a cross-sectional study of 888 patients with stage 3–5 CKD and data on serum C-reactive protein (CRP) levels and a concomitant food frequency questionnaire. We estimated the odds ratios (ORs) [95% confidence interval (CI)] for various CRP thresholds (>3, >4, >5, >6, and >7 mg/L) associated with three intake categories (no yoghurt, ordinary yoghurt, and probiotics from yoghurts or dietary supplements) and two frequency categories (daily or less than daily).

Results

The 888 study participants (median age: 70; men: 65%) had a median estimated glomerular filtration rate of 28.6 mL/min/1.73 m² and a median [interquartile range] CRP level of 3.0 [1.6, 7.0] mg/L. Fifty-seven percent consumed ordinary yoghurt and 30% consumed probiotic yoghurt. The median intake frequency for yoghurt and probiotics was 7 per week. Relative to participants not consuming yoghurt, the ORs [95% CI] for CRP > 6 or >7 mg/L were significantly lower for participants consuming ordinary yoghurt (0.58 [0.37, 0.93] and 0.57 [0.35, 0.91], respectively) and for participants consuming probiotics (0.54 [0.33, 0.9] and 0.48 [0.28, 0.81], respectively), independently of age, sex, body mass index, CKD stage, cardiovascular disease, and fibre, protein and total energy intakes. The ORs were not significantly lower for CRP thresholds >3, >4, and >5 mg/L and were not significantly greater in daily consumers than in occasional consumers.

Conclusion

We observed independent associations between the consumption of yoghurt or probiotics and lower levels of inflammation in patients with CKD. There was no evidence of a dose-effect relationship.

Clinical Trial Registration

[https://www.clinicaltrials.gov/ct2/show/NCT03381950], identifier [NCT03381950].

The Therapeutic Strategies for Uremic Toxins Control in Chronic Kidney Disease

Uremic toxins (UTs) are mainly produced by protein metabolized by the intestinal microbiota and converted in the liver or by mitochondria or other enzymes. The accumulation of UTs can damage the intestinal barrier integrity and cause vascular damage and progressive kidney damage. Together, these factors lead to metabolic imbalances, which in turn increase oxidative stress and inflammation and then produce uremia that affects many organs and causes diseases including renal fibrosis, vascular disease, and renal osteodystrophy. This article is based on the theory of the intestinal-renal axis, from bench to bedside, and it discusses nonextracorporeal therapies for UTs, which are classified into three categories: medication, diet and supplement therapy, and complementary and alternative medicine (CAM) and other therapies. The effects of medications such as AST-120 and meclofenamate are described. Diet and supplement therapies include plant-based diet, very low-protein diet, probiotics, prebiotics, synbiotics, and nutraceuticals. The research status of Chinese herbal medicine is discussed for CAM and other therapies. This review can provide some treatment recommendations for the reduction of UTs in patients with chronic kidney disease.

Dietary fibre intake is low in paediatric chronic kidney disease patients but its impact on levels of gut-derived uraemic toxins remains uncertain

BACKGROUND

Chronic kidney disease (CKD) in children is a pro-inflammatory condition leading to a high morbidity and mortality. Accumulation of organic metabolic waste products, coined as uraemic toxins, parallels kidney function decline. Several of these uraemic toxins are protein-bound (PBUT) and gut-derived. Gut dysbiosis is a hallmark of CKD, resulting in a state of increased proteolytic fermentation that might be counteracted by dietary fibre. Data on fibre intake in children with CKD are lacking. We aimed to assess dietary fibre intake in a paediatric CKD cohort and define its relationship with PBUT concentrations.

METHODS

In this multi-centre, cross-sectional observational study, 61 non-dialysis CKD patients (9 ± 5 years) were included. Dietary fibre intake was assessed through the use of 24-h recalls or 3-day food records and coupled to total and free levels of 4 PBUTs (indoxyl sulfate (IxS), p-cresyl sulfate (pCS), p-cresyl glucuronide (pCG) and indole acetic acid (IAA).

RESULTS

In general, fibre intake was low, especially in advanced CKD: 10 ± 6 g/day/BSA in CKD 4-5 versus 14 ± 7 in CKD 1-3 (p = 0.017). Lower concentrations of both total (p = 0.036) and free (p = 0.036) pCG were observed in the group with highest fibre intake, independent of kidney function.

CONCLUSIONS

Fibre intake in paediatric CKD is low and is even worse in advanced CKD stages. Current dietary fibre recommendations for healthy children are not being achieved. Dietary management of CKD is complex in which too restrictive diets carry the risk of nutritional deficiencies. The relation of fibre intake with PBUTs remains unclear and needs further investigation. Graphical abstract.

Dietary Fibre Intake Is Associated with Serum Levels of Uraemic Toxins in Children with Chronic Kidney Disease

Imbalanced colonic microbial metabolism plays a pivotal role in generating protein-bound uraemic toxins (PBUTs), which accumulate with deteriorating kidney function and contribute to the uraemic burden of children with chronic kidney disease (CKD). Dietary choices impact the gut microbiome and metabolism. The aim of this study was to investigate the relation between dietary fibre and gut-derived PBUTs in paediatric CKD. Sixty-one (44 male) CKD children (9 ± 5 years) were prospectively followed for two years. Dietary fibre intake was evaluated by either 24-h recalls (73%) or 3-day food records (27%) at the same time of blood sampling for assessment of total and free serum levels of different PBUTs using liquid chromatography. We used linear mixed models to assess associations between fibre intake and PBUT levels. We found an inverse association between increase in fibre consumption (g/day) and serum concentrations of free indoxyl sulfate (−3.1% (−5.9%; −0.3%) (p = 0.035)), free p-cresyl sulfate (−2.5% (−4.7%; −0.3%) (p = 0.034)), total indole acetic acid (IAA) (−1.6% (−3.0%; −0.3%) (p = 0.020)), free IAA (−6.6% (−9.3%; −3.7%) (p < 0.001)), total serum p-cresyl glucuronide (pCG) (−3.0% (−5.6%; −0.5%) (p = 0.021)) and free pCG levels (−3.3% (−5.8%; −0.8%) (p = 0.010)). The observed associations between dietary fibre intake and the investigated PBUTs highlight potential benefits of fibre intake for the paediatric CKD population. The present observational findings should inform and guide adaptations of dietary prescriptions in children with CKD.

Challenges of reducing protein-bound uremic toxin levels in chronic kidney disease and end stage renal disease

The prevalence of chronic kidney disease (CKD) in the worldwide population is currently estimated between 11% and 13%. Adequate renal clearance is compromised in these patients and the accumulation of a large number of uremic retention solutes results in an irreversible worsening of renal function which can lead to end stage renal disease (ESRD). Approximately three million ESRD patients currently receive renal replacement therapies (RRTs), such as hemodialysis, which only partially restore kidney function, as they are only efficient in removing mainly small, unbound solutes from the circulation while leaving larger and protein-bound uremic toxins (PBUTs) untouched. The accumulation of PBUTs in patients highly increases the risk of cardiovascular events and is associated with higher mortality and morbidity in CKD and ESRD. In this review, we address several strategies currently being explored toward reducing PBUT concentrations, including clinical and medical approaches, therapeutic techniques, and recent developments in RRT technology. These include preservation of renal function, limitation of colon derived PBUTs, oral sorbents, adsorbent RRT technology, and use of albumin displacers. Despite the promising results of the different approaches to promote enhanced removal of a small percentage of the more than 30 identified PBUTs, on their own, none of them provide a treatment with the required efficiency, safety and cost-effectiveness to prevent CKD-related complications and decrease mortality and morbidity in ESRD.

Systematic Review of Nutrition Supplements in Chronic Kidney Diseases: A GRADE Approach

Chronic kidney disease (CKD) is cumulative worldwide and an increasing public health issue. Aside from the widely known protein restriction and medical therapy, less evident is the renal protection of nutrition supplements in CKD patients. This systematic review (SR), using a Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach, aims to summarize and quantify evidence about the prevention effects of vitamin D and analogues, omega-3 polyunsaturated fatty acid (omega-3 PUFA), dietary fiber, coenzyme Q10 (CoQ10), and biotics on CKD progression. This study was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement to examine SRs and/or meta-analysis of clinical controlled trials identified from PubMed, Embase, and the Cochrane Library. Finally, seventeen SRs were included in the qualitative analysis. The beneficial effects of these nutrition supplements in CKD patients mostly seem to be at low to very low evidence on proteinuria, kidney function, and inflammations and did not appear to improve CKD prognosis. The recommendation of nutrition supplements in CKD patients needs to discuss with physicians and consider the benefits over the adverse effects. Longer follow-up of larger randomized trials is necessary to clarify the benefits of nutrition supplements in CKD patients.

Kidney diseases and COVID-19 infection: causes and effect, supportive therapeutics and nutritional perspectives

Recently, the novel coronavirus disease 2019 (COVID-19), has attracted the attention of scientists where it has a high mortality rate among older adults and individuals suffering from chronic diseases, such as chronic kidney diseases (CKD). It is important to elucidate molecular mechanisms by which COVID-19 affects the kidneys and accordingly develop proper nutritional and pharmacological strategies. Although numerous studies have recently recommended several approaches for the management of COVID-19 in CKD, its impact on patients with renal diseases remains the biggest challenge worldwide. In this paper, we review the most recent evidence regarding causality, potential nutritional supplements, therapeutic options, and management of COVID-19 infection in vulnerable individuals and patients with CKD. To date, there is no effective treatment for COVID-19-induced kidney dysfunction, and current treatments are yet limited to anti-inflammatory (e.g. ibuprofen) and anti-viral medications (e.g. Remdesivir, and Chloroquine/Hydroxychloroquine) that may increase the chance of treatment. In conclusion, the knowledge about kidney damage in COVID-19 is very limited, and this review improves our ability to introduce novel approaches for future clinical trials for this contiguous disease.

The Efficacy of Lactobacillus-Containing Probiotic Supplementation in Hemodialysis Patients: A Randomized, Double-Blind, Placebo-Controlled Trial

OBJECTIVES

This study was performed to determine the effects of probiotic supplementation on cholesterol-triglyceride ratio, an indirect marker of insulin resistance, protein-bound uremic toxins, biomarkers of inflammation, and microbial translocation in end-stage renal disease patients on hemodialysis.

METHODS

Fifty-six patients aged 39-75 years were assigned into two groups to receive either probiotic sachets (n = 28) or a placebo (n = 28) in a randomized double-blinded placebo-controlled clinical trial. The patients in the probiotic group received twice daily sachets that contained a mixture of three viable and freeze-dried strains: Lactococcus lactis subsp. Lactis LL358, Lactobaccillus salivarius LS159, and Lactobaccillus pentosus LPE588 at high dose (100 billion; 1 × 10¹¹ cfu/day) for 6 months.

RESULTS

A total of 50 patients were available for final analysis. Probiotic supplementation did not have a significant influence on cholesterol-triglyceride ratio. Probiotic supplementation for 6 months caused a significant decrease in serum levels of indoxyl sulfate. Compared with the placebo, probiotic supplementation did not result in significant changes in hemoglobin levels, blood urea nitrogen, blood glucose, serum p-cresyl sulfate, inflammatory, and microbial translocation markers. No clinically significant changes in body composition were observed between the two groups during the study period. The probiotic supplementation was well tolerated by all subjects with minimal adverse effects during the 6-month-long study.

CONCLUSION

Our results suggest that high-dose multistrain lactobaccillus probiotic supplementation over 6 months as a monotherapy did not significantly decrease markers of insulin resistance, cholesterol-triglyceride ratio, and most of the studied markers, with the exception of levels of indoxyl sulfate in patients on HD.

Probiotics, prebiotics, and synbiotics for the improvement of metabolic profiles in patients with chronic kidney disease: A systematic review and meta-analysis of randomized controlled trials

This systematic review and meta-analysis of randomized controlled trials (RCTs) was performed to quantify the effects of probiotic, prebiotic, and synbiotic supplementation on biomarkers of inflammation and oxidative stress, as well as lipid profiles among patients with chronic kidney disease (CKD). Electronic databases, including PubMed, the Cochrane Database, and the Web of Science were searched from January 1, 2000, to May 15, 2019. All RCTs that investigated the effect of prebiotics, probiotics, and synbiotics on a circulating (serum and plasma) inflammatory marker (C-reactive protein [CRP]), oxidative stress indicators (malondialdehyde [MDA], glutathione [GSH], and total anti-oxidant capacity [TAC]); and lipid profiles (total cholesterol [TC], triglycerides [TG], low-density lipoprotein cholesterol [LDL-c], and high-density lipoprotein cholesterol [HDL-c]) among patients with CKD were included. Data were pooled and expressed as a standardized mean difference (SMD) with a 95% confidence interval (CI). The protocol for this meta-analysis is registered with PROSPERO; No. CRD42019139090. Thirteen trials that included 671 patients were identified for analysis. The methodological quality varied across studies. Meta-analysis indicated that microbial therapies significantly reduced CRP (SMD, -0.75; 95% CI, -1.03 to -0.47; p = 0.000), MDA (SMD, -1.06; 95% CI, -1.59 to -0.52; p = 0.000), TC (SMD, -0.33; 95% CI, -0.52 to -0.13; p = 0.000), and LDL-c (SMD, -0.44; 95% CI, -0.86 to -0.02; p = 0.000) levels; they also increased the GSH (SMD, 0.44; 95% CI, 0.25 to 0.65; p = 0.000), TAC (SMD, 0.61; 95% CI, 0.07 to 1.15; p = 0.000), and HDL-c (SMD, 0.45; 95% CI, 0.03 to 0.87; p = 0.000) levels in CKD patients, as compared to the placebo groups; however, there was no statistically significant TG concentration among patients with CKD. Subgroup analyses showed that other key factors, such as the duration of intervention, participants' baseline body mass index (BMI), type of intervention, and age, had an effect of microbial therapies on outcomes. This meta-analysis supports the potential use of probiotic, prebiotic, and synbiotic supplements in the improvement of established biomarkers of inflammation and oxidative stress, as well as lipid profiles among patients with CKD, which are well-known cardiovascular risk factors. Further research into these interventions should consider the limitations of our study to explore the effect of long-term administration of these supplements in the CKD population.

The International Scientific Association for Probiotics and Prebiotics (ISAPP) consensus statement on the definition and scope of synbiotics

In May 2019, the International Scientific Association for Probiotics and Prebiotics (ISAPP) convened a panel of nutritionists, physiologists and microbiologists to review the definition and scope of synbiotics. The panel updated the definition of a synbiotic to "a mixture comprising live microorganisms and substrate(s) selectively utilized by host microorganisms that confers a health benefit on the host". The panel concluded that defining synbiotics as simply a mixture of probiotics and prebiotics could suppress the innovation of synbiotics that are designed to function cooperatively. Requiring that each component must meet the evidence and dose requirements for probiotics and prebiotics individually could also present an obstacle. Rather, the panel clarified that a complementary synbiotic, which has not been designed so that its component parts function cooperatively, must be composed of a probiotic plus a prebiotic, whereas a synergistic synbiotic does not need to be so. A synergistic synbiotic is a synbiotic for which the substrate is designed to be selectively utilized by the co-administered microorganisms. This Consensus Statement further explores the levels of evidence (existing and required), safety, effects upon targets and implications for stakeholders of the synbiotic concept.

Gut Dysbiosis and the Intestinal Microbiome: Streptococcus thermophilus a Key Probiotic for Reducing Uremia

In the intestines, probiotics can produce antagonistic effects such as antibiotic–like compounds, bactericidal proteins such as bacteriocins, and encourage the production of metabolic end products that may assist in preventing infections from various pathobionts (capable of pathogenic activity) microbes. Metabolites produced by intestinal bacteria and the adoptions of molecular methods to cross-examine and describe the human microbiome have refreshed interest in the discipline of nephology. As such, the adjunctive administration of probiotics for the treatment of chronic kidney disease (CKD) posits that certain probiotic bacteria can reduce the intestinal burden of uremic toxins. Uremic toxins eventuate from the over manifestation of glucotoxicity and lipotoxicity, increased activity of the hexosamine and polyol biochemical and synthetic pathways. The accumulation of advanced glycation end products that have been regularly associated with a dysbiotic colonic microbiome drives the overproduction of uremic toxins in the colon and the consequent local pro-inflammatory processes. Intestinal dysbiosis associated with significant shifts in abundance and diversity of intestinal bacteria with a resultant and maintained uremia promoting an uncontrolled mucosal pro-inflammatory state. In this narrative review we further address the efficacy of probiotics and highlighted in part the probiotic bacterium Streptococcus thermophilus as an important modulator of uremic toxins in the gut of patients diagnosed with chronic kidney disease. In conjunction with prudent nutritional practices it may be possible to prevent the progression of CKD and significantly downregulate mucosal pro-inflammatory activity with the administration of probiotics that contain S. thermophilus.

Dietary Components That May Influence the Disturbed Gut Microbiota in Chronic Kidney Disease

Gut microbiota imbalance is common in patients with chronic kidney disease (CKD) and associates with factors such as increased circulating levels of gut-derived uremic toxins, inflammation, and oxidative stress, which are linked to cardiovascular disease and increased morbimortality. Different nutritional strategies have been proposed to modulate gut microbiota, and could potentially be used to reduce dysbiosis in CKD. Nutrients like proteins, fibers, probiotics, and synbiotics are important determinants of the composition of gut microbiota and specific bioactive compounds such as polyphenols present in nuts, berries. and fruits, and curcumin, may also play a key role in this regard. However, so far, there are few studies on dietary components influencing the gut microbiota in CKD, and it is therefore not possible to conclude which nutrients should be prioritized in the diet of patients with CKD. In this review, we discuss some nutrients, diet patterns and bioactive compounds that may be involved in the modulation of gut microbiota in CKD and provide the background and rationale for studies exploring whether nutritional interventions with these dietary components could be used to alleviate the gut dysbiosis in patients with CKD.

Supplementation of Short-Chain Fatty Acid, Sodium Propionate, in Patients on Maintenance Hemodialysis: Beneficial Effects on Inflammatory Parameters and Gut-Derived Uremic Toxins, A Pilot Study (PLAN Study)

BACKGROUND

In end-stage renal disease (ESRD), gut-derived uremic toxins play a crucial role in the systemic inflammation and oxidative stress promoting the excess morbidity and mortality. The biochemical derangement is in part a consequence of an insufficient generation of short-chain fatty acids (SCFA) due to the dysbiosis of the gut and an insufficient consumption of the fermentable complex carbohydrates.

AIM OF THE STUDY

The primary end-point was to evaluate the potential efficacy of SCFA (specifically, sodium propionate (SP)) for patients on maintenance hemodialysis (MHD) on systemic inflammation. Secondary end-points included potential attenuation of oxidative stress markers, insulin resistance and production of gut-derived uremic toxins indoxyl sulfate and p-cresol sulfate, as well as health status after SP supplementation.

STUDY DESIGN

We performed a single-center non-randomized pilot study in 20 MHD patients. They received the food additive SP with a daily intake of 2 × 500 mg in the form of capsules for 12 weeks. Pre-dialysis blood samples were taken at the beginning, after six weeks and at the end of the administration period, as well as four weeks after withdrawal of the treatment.

RESULTS

The subjects revealed a significant decline of inflammatory parameters C-reactive protein (-46%), interleukin IL-2 (-27%) and IL-17 (-15%). The inflammatory parameters IL-6 and IFN-gamma showed a mild non-significant reduction and the anti-inflammatory cytokine IL-10 increased significantly (+71%). While the concentration of bacterial endotoxins and TNF-α remained unchanged, the gut-derived uremic toxins, indoxyl sulfate (-30%) and p-cresyl sulfate (-50%), revealed a significant decline. The SP supplementation reduced the parameters of oxidative stress malondialdehyde (-32%) and glutathione peroxidase activity (-28%). The serum insulin levels dropped by 30% and the HOMA-index by 32%. The reduction of inflammatory parameters was associated with a lowering of ferritin and a significant increase in transferrin saturation (TSAT). Four weeks after the end of the treatment phase, all improved parameters deteriorated again. Evaluation of the psycho-physical performance with the short form 36 (SF-36) questionnaire showed an enhancement in the self-reported physical functioning, general health, vitality and mental health. The SP supplementation was well tolerated and without important side effects. No patient had left the study due to intolerance to the medication. The SP supplementation in MHD patients reduced pro-inflammatory parameters and oxidative stress and improved insulin resistance and iron metabolism. Furthermore, SP effectively lowered the important gut-derived uremic toxins indoxyl and p-cresol sulfate. These improvements were associated with a better quality of life. Further controlled studies are required in a larger cohort to evaluate the clinical outcome.