In Vitro and In Vivo Assessment of Intraintestinal Bacteriotherapy in Chronic Kidney Disease

A new generation of mesenchymal stromal/stem cells differentially trained by immunoregulatory probiotics in a lupus microenvironment

BACKGROUND

Increasing evidence suggests that multipotent mesenchymal stem/stromal cells (MSCs) are a promising intervention strategy in treating autoimmune inflammatory diseases. It should be stated that systemic immunoregulation is increasingly recognized among the beneficial effects of MSCs and probiotics in treating morbid autoimmune disorders such as lupus. This study aimed to determine if immunoregulatory probiotics L. rhamnosus or L. delbrueckii can change the immunomodulatory effects of MSCs in lupus-like disease.

METHODS

Pristane-induced lupus (PIL) mice model was created via intraperitoneal injection of Pristane and then confirmed. Naïve MSCs (N-MSCs) were coincubated with two Lactobacillus strains, rhamnosus (R-MSCs) or delbrueckii (D-MSCs), and/or a combination of both (DR-MSCs) for 48 h, then administrated intravenously in separate groups. Negative (PBS-treated normal mice) and positive control groups (PBS-treated lupus mice) were also investigated. At the end of the study, flow cytometry and enzyme-linked immunosorbent assay (ELISA) analysis were used to determine the percentage of Th cell subpopulations in splenocytes and the level of their master cytokines in sera, respectively. Moreover, lupus nephritis was investigated and compared. Analysis of variance (ANOVA) was used for multiple comparisons.

RESULTS

Abnormalities in serum levels of anti-dsDNA antibodies, creatinine, and urine proteinuria were significantly suppressed by MSCs transplantation, whereas engrafted MSCs coincubation with both L. strains did a lesser effect on anti-dsDNA antibodies. L. rhamnosus significantly escalated the ability of MSCs to scale down the inflammatory cytokines (IFN-ɣ, IL-17), while L. delbrueckii significantly elevated the capacity of MSCs to scale down the percentage of Th cell subpopulations. However, incubation with both strains induced MSCs with augmented capacity in introducing inflammatory cytokines (IFN-ɣ, IL-17). Strikingly, R-MSCs directly restored the serum level of TGF-β more effectively and showed more significant improvement in disease parameters than N-MSCs. These results suggest that R-MSCs significantly attenuate lupus disease by further skew the immune phenotype of MSCs toward increased immunoregulation.

CONCLUSIONS

Results demonstrated that Lactobacillus strains showed different capabilities in training/inducing new abilities in MSCs, in such a way that pretreated MSCs with L. rhamnosus might benefit the treatment of lupus-like symptoms, given their desirable properties.

Oral administration of vancomycin alleviates heart failure triggered by chronic kidney disease

Chronic kidney disease (CKD) induces an imbalance in the intestinal microbiota, affecting various physiological functions and leading to cardiovascular inflammation and fibrosis. However, the cardiotoxic impact of intestinal microbiota-derived uremic substances in advanced renal dysfunction remains unexplored. Therefore, we developed a 5/6 nephrectomy (5/6Nx) mouse model to investigate the intestinal microbiota and the effects of administering vancomycin (VCM) on the microbiota and the cardiac pathology associated with CKD. Despite VCM administration after the development of irreversible glomerulosclerosis and tubulointerstitial fibrosis, blood indoxyl sulfate and phenyl sulfate levels, which are intestinal bacteria-derived uremic substances, brain natriuretic peptide levels, and the fibrotic area in the heart were decreased. Moreover, VCM administration prevented 5/6Nx-induced weight loss and prolonged survival time. Our findings suggest that VCM-induced changes in the intestinal microbiota composition ameliorate heart failure and improve survival rates by reducing intestinal microbiota-derived cardiotoxic substances despite advanced renal dysfunction. This highlights the potential of using the intestinal microbiota as a target to prevent and treat cardiovascular conditions associated with CKD.

The ameliorating effect of limosilactobacillus fermentum and its supernatant postbiotic on cisplatin-induced chronic kidney disease in an animal model

BACKGROUND

Chronic kidney disease (CKD) is a worldwide public health problem affecting millions of people. Probiotics and postbiotics are associated with valuable compounds with antibacterial, anti-inflammatory, and immunomodulatory effects, preserving renal function in CKD patients. The current study is aimed to evaluate the efficacy of Limosilactobacillus fermentum (L. fermentum) and its postbiotic in an animal model of cisplatin-induced CKD.

METHODS

The animals were divided into four experimental groups (normal mice, CKD mice with no treatment, CKD mice with probiotic treatment, and CKD mice with postbiotic treatment). CKD mice were induced by a single dose of cisplatin 10 mg/kg, intraperitoneally. For 28 days, the cultured probiotic bacteria and its supernatant (postbiotic) were delivered freshly to the related groups through their daily water. Then, blood urea nitrogen (BUN) and creatinine (Cr) of plasma samples as well as glutathione (GSH), lipid peroxidation, reactive oxygen species, and total antioxidant capacity of kidneys were assessed in the experimental mice groups. In addition, histopathological studies were performed on the kidneys.

RESULTS

Application of L. fermentum probiotic, and especially postbiotics, significantly decreased BUN and Cr (P < 0.0001) as well as ROS formation and lipid peroxidation levels (P < 0.0001) along with increased total antioxidant capacity and GSH levels (P < 0.001). The histopathologic images also confirmed their renal protection effect. Interestingly, the postbiotic displayed more effectiveness than the probiotic in some assays. The improvement effect on renal function in the current model is mainly mediated by oxidative stress markers in the renal tissue.

CONCLUSIONS

In conclusion, it was found that the administration of L. fermentum probiotic, and particularly its postbiotic in cisplatin-induced CKD mice, showed promising effects and could successfully improve renal function in the animal model of CKD. Therefore, probiotics and postbiotics are considered as probably promising alternative supplements to be used for CKD.

Regulation of gut microbiota: a novel pretreatment for complications in patients who have undergone kidney transplantation

Kidney transplantation is an effective method to improve the condition of patients with end-stage renal disease. The gut microbiota significantly affects the immune system and can be used as an influencing factor to change the prognoses of patients who have undergone kidney transplantation. Recipients after kidney transplantation showed a lower abundance of Firmicutes and Faecalibacterium prausnitzii and a higher proportion of Bacteroidetes and Proteobacteria. After using prebiotics, synbiotics, and fecal microbiota transplantation to regulate the microbial community, the prognoses of patients who underwent kidney transplantation evidently improved. We aimed to determine the relationship between gut microbiota and various postoperative complications inpatients who have undergone kidney transplantation in recent years and to explore how gut microecology affects post-transplant complications. An in-depth understanding of the specific functions of gut microbiota and identification of the actual pathogenic flora during complications in patients undergoing kidney transplantation can help physicians develop strategies to restore the normal intestinal microbiome of transplant patients to maximize their survival and improve their quality of life.

Evaluation of the effectiveness of two new strains of Lactobacillus on obesity-induced kidney diseases in BALB/c mice

Background

Kidney disease (KD) is a public health problem worldwide and is an important factor in peripheral vascular disease, arrhythmias, heart failure, acute myocardial infarction, stroke, and angina. Obesity has been indicated as an effective cause of kidney diseases. So, this study aims to use two new strains of Lactobacillus to reduce the metabolic disorders and kidney insufficiency associated with obesity.

Methods

Fifty BALB/c male mice were divided into five groups (control, obesity, obesity pro1, obesity pro2, and obesity mix). The bodyweight, cholesterol profile, urea, and creatinine levels in urine and serum were all measured. Histopathological analysis and expression of Opn, Vim, Ngal, Kim-1, and αKlotho genes for kidney tissues were performed.

Results

The results indicated that body weight, cholesterol profile, urea, and creatinine levels in serum and urine had the lowest significance (P ˂ 0.05) in the obesity mix group and the highest significance in the obesity group. HDL had the highest significance (P ˂ 0.05) in the obesity mix group and the lowest significance (P ˂ 0.05) in the obesity group. Expression of Opn, Vim, Ngal, and Kim-1 genes was the most upregulated in the obesity group compared with the other groups, and there were nonsignificant differences (P > 0.05) between the obesity pro1 and obesity mix groups and the control group. Expression of αKlotho gene was significantly reduced (P ˂ 0.05) in the obesity group compared with the control group.

Conclusion

This study demonstrated that the combination of pro1 and pro2 strains could reduce kidney inflammation and necrosis.

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.

Effectiveness of new selenium-enriched mutated probiotics in reducing inflammatory effects of piroxicam medication in liver and kidney

Piroxicam is used to treat the pain, swelling, and stiffness associated with osteoarthritis and rheumatoid arthritis, but it has many side effects, such as hypertension, elevation of liver enzymes, and hepatitis. This study used selenium-enriched probiotics to reduce the side effects of piroxicam on the liver and kidney tissues and functions. Forty-eight male albino mice were randomly assigned to control, piroxicam (P), piroxicam plus selenium-enriched Lactobacillus plantarum PSe40/60/1 (P + SP), piroxicam plus selenium-enriched Bifidobacterium longum BSe50/20/1 (P + SB), selenium-enriched L. plantarum PSe40/60/1 (SP), and selenium-enriched B. longum BSe50/20/1 (SB) groups. In this study, the function of the liver and kidney was biochemically determined; the histopathology of the liver and kidney tissues was microscopically examined and the expression of inflammatory and anti-inflammatory genes in liver and kidney tissues was determined by quantitative real-time polymerase chain reaction (qRT-PCR). Liver and kidney functions were significantly reduced in the piroxicam group compared with control. Liver and kidney tissues were damaged in the piroxicam group while they appeared more or less normal in the SB group. The expression of inflammatory genes was significantly up-regulated in the liver and kidney tissues of the piroxicam group compared to the control group. The expression of anti-inflammatory genes was significantly down-regulated in the liver and kidney of the piroxicam group and up-regulated in the liver and kidney of the SB group compared to the control group. Therefore, these mutated strains of probiotics were useful in reducing the side effects of the piroxicam drug on the liver and kidney.

Biotic Supplements in Patients With Chronic Kidney Disease: Meta-Analysis of Randomized Controlled Trials

OBJECTIVE

Gut flora imbalance characterizes patients with chronic kidney disease (CKD). Although biotic supplementation has been proposed to lessen inflammation and oxidative stress and, thus, reduce the risk of progressive kidney damage and cardiovascular disease, the effects remain controversial. We conducted a meta-analysis to assess the therapeutic benefits of biotics in CKD.

METHODS

PubMed, Embase, and Cochrane databases were systematically searched for randomized controlled trials that evaluated any biotic (prebiotic, probiotic, synbiotics) supplements in patients with CKD (CKD, stage 3-4 to end-stage renal disease). Primary endpoints included changes in renal function, markers of inflammation, and oxidative stress. Secondary endpoints included changes in levels of uremic toxins and variations in lipid metabolism.

RESULTS

Twenty-three eligible studies included 842 participants. In a pooled-analysis, biotics did not change estimated glomerular filtration rate (mean difference [MD] = 0.08, P = .92) or serum albumin (MD = -0.01, P = .86), although prebiotics reduced serum creatinine (standardized mean difference [SMD] = -0.23, P = .009) and blood urea nitrogen (MD = -6.05, P < .00001). Biotics improved total antioxidative capacity (SMD = 0.37, P = .007) and malondialdehyde (SMD = -0.96, P = .006) and reduced the inflammatory marker interleukin-6 (SMD = -0.30, P = .01) although not C-reactive protein (SMD = -0.22, P = .20). Biotic intervention reduced some uremic toxins, including p-cresol sulfate (SMD = -2.18, P < .0001) and indoxyl sulfate (MD = -5.14, P = .0009), which decreased in dialysis-dependent patients. Another toxin, indole-3-acetic acid (MD = -0.22, P = .63), did not change. Lipids were unaffected by biotic intervention (total cholesterol: SMD = -0.01, P = .89; high-density lipoprotein: SMD = -0.08, P = .76; low-density lipoprotein: MD = 3.54, P = .28; triglyceride: MD = -2.26, P = .58).

CONCLUSION

The results highlight the favorable influence of biotics on circulating markers of creatinine, oxidant stress (malondialdehyde, total antioxidative capacity), inflammation (interleukin-6), and uremic toxins (p-cresol sulfate) in patients with CKD. Biotics did not affect estimated glomerular filtration rate, albumin, indole-3-acetic acid, or lipids in either predialysis or dialysis patients.

Therapeutic Prospective of a Spore-Forming Probiotic-Bacillus clausii UBBC07 Against Acetaminophen-Induced Uremia in Rats

To screen Bacillus clausii UBBC07 as a putative probiotic strain and to examine the protective effect of probiotic-B. clausii UBBC07 spore on uremia on rats induced by acetaminophen. In vitro tests performed to screen potential probiotic strains were gastric and bile acid resistance and ability to reduce pathogen adhesion to surfaces. An in vivo study was performed on rats (n = 18) which were randomly divided into three groups: group I, control-receives normal food and water, groups II and III receive acetaminophen i.p. at the dose of 550 mg/kg/day for 10 days, groups III was treated with B. clausii UBBC07 at a dose of 1 × 10⁹ CFU/day for 15 days. Urea, creatinine, malondialdehyde (MDA), and GSH levels and antioxidant enzymes like super oxide dismutase (SOD) and catalase activity were considered to analyze renal failure. Plasma urea and creatinine levels (p < 0.05) significantly increase and SOD, catalase, and GSH activity level significantly decrease in group II as compared with the control group. After treatment with probiotic, there was a significant increase in SOD and catalase (p < 0.05) and a significant decrease in serum urea, creatinine, and MDA (p < 0.05) in group III in response to group II. The results also revealed that probiotic was able to tolerate pH 3.0-9.0 and 0.3% bile salt. The present study suggests that B. clausii UBBC07 could be used as a novel alternative natural therapy for uremia, a major syndrome of CKD.

Effect of a Probiotic Combination in an Experimental Mouse Model and Clinical Patients With Chronic Kidney Disease: A Pilot Study

The aim of the present study was to evaluate whether probiotic administration could slow declining renal function. C57BL/6 mice (6–8 weeks of age, male) were fed a diet supplemented with adenine to induce chronic kidney disease (CKD). The experimental groups were additionally supplemented with 10⁹ colony-forming units (CFU)/day (high-dose) and 10⁷ CFU/day (low-dose) probiotics containing Lactobacillus acidophilus (TYCA06), Bifidobacterium longum subspecies infantis (BLI-02), and B. bifidum (VDD088). Renal function and histology were examined. Patients with stage 3–5 CKD and not on dialysis were recruited from July 2017 to January 2019. Two capsules of probiotics containing 2.5 × 10⁹ CFU with the same composition were administered twice daily for 6 months. The decline in the estimated glomerular filtration rate (eGFR) was measured before and after the intervention. In addition, changes in the serum endotoxin and cytokine levels, gastrointestinal symptom scores, and the stool microbiota were measured. Probiotics could attenuate renal fibrosis and improve renal function in CKD mice. Thirty-eight patients completed the 6-month study. The mean baseline eGFR was 30.16 ± 16.52 ml/min/1.73 m². The rate of decline in the eGFR was significantly slower, from −0.54 (−0.18, −0.91) to 0.00 (0.48, −0.36) ml/min/1.73 m²/month (P = 0.001) after 6 months of treatment. The serum levels of TNF-α, IL-6, IL-18, and endotoxin were significantly decreased after probiotic administration. Borborygmus and flatulence scores, as well as stool formation improved significantly. The abundance of B. bifidum and B. breve in the stool microbiota increased significantly. In conclusion, a combination of probiotics might attenuate renal function deterioration in CKD mice and human patients.

Gut Microbial Changes in Diabetic db/db Mice and Recovery of Microbial Diversity upon Pirfenidone Treatment

The leptin receptor-deficient db/db mouse model is an accepted in vivo model to study obesity, type 2 diabetes, and diabetic kidney disease. Healthy gastrointestinal (GI) microbiota has been linked to weight loss, improved glycemic control, and physiological benefits. We investigated the effect of various drugs on the GI microbiota of db/db mice as compared to control db/m mice. Treatment with long-acting pirfenidone (PFD) increased gut microbial diversity in diabetic db/db mice. Firmicutes, the most abundant phylum in db/m mice, decreased significantly in abundance in db/db mice but showed increased abundance with long-acting PFD treatment. Several bacterial taxa, including Lactobacillus and some Bacteroides, were less abundant in db/db mice and more abundant in long-acting-PFD-treated db/db mice. Long-acting PFD treatment reduced the abundance of Akkermansia muciniphila (5%) as compared to db/db mice (~15%). We conclude that gut microbial dysbiosis observed in db/db mice was partially reversed by long-acting PFD treatment and hypothesize that PFD has beneficial effects, in part, via its influence on the gut microbial metabolite profile. In quantitatively assessing urine metabolites, we observed a high abundance of diabetic ketoacidosis biomarkers, including 3-hydroxybutyric acid and acetoacetic acid in db/db mice, which were less abundant in the long-acting-PFD-treated db/db mice.

Pilot Study of Probiotic Supplementation on Uremic Toxicity and Inflammatory Cytokines in Chronic Kidney Patients

Background:

Bacterial metabolism contributes to the generation of uremic toxins in patients with chronic kidney disease (CKD). It has been investigated the use of probiotics in the reduction of uremic toxins intestinal production.

Objective:

The aim of this pilot study was to evaluate the effect of probiotic supplementation on reducing the production of uremic toxins and the inflammatory profile of CKD patients.

Methods:

We performed a randomized, blind, placebo-controlled, crossover study on patients with CKD stages 3 and 4. The intervention was a probiotic formulation composed of Lactobacillus acidophilus strains given orally three times a day for 3 months. Changes in uremic toxins (p-Cresylsulfate and Indoxyl Sulfate) and serum inflammatory cytokines were the primary endpoints.

Results:

Of the 44 patients randomized, 25 completed the study (mean age 51 ± 9.34, 64% female, mean eGFR 36 ± 14.26 mL/min/1.73m², mean BMI 28.5 ± 5.75 kg/m²). At 3 months, there were no significant changes in any of the studied biomarkers including p-cresylsulfate (p = 0.57), Indoxyl sulfate (p = 0.08) and interleukin-6 (p = 0.55).

Conclusion:

Lactobacillus acidophilus strains given as probiotic were not able to reduce serum levels of uremic toxins and biomarkers of inflammation in CKD patients in stage 3 and 4.

Intestinal microbiota alterations in chronic kidney disease and the influence of dietary components

In chronic kidney disease, as in many other diseases, dysbiosis of intestinal microbiota has been reported as a disturbance or imbalance of the normal microbiome content that could disrupt the symbiotic relationship between the host and associated microbes, a disruption that can result in diseases. The disruption of gut barrier function allows the translocation of endotoxins and bacterial metabolites to the organism, thus contributing to uremic toxicity, inflammation and progression of chronic kidney disease. Increased intake of some nutrients and different nutritional strategies have been proposed to modulate gut microbiota, thus offering the opportunity for therapeutic interventions modifying the diet, decreasing uremic toxins production, increasing toxin excretion and finally modifying the normal microbiome content. The use of probiotics, prebiotics and low protein diets, among other approaches, could also improve this imbalance and/or decrease permeability of the intestinal barrier. In this review, the link between nutrients, microbiota and uremic toxins with chronic kidney disease progression has been studied thoroughly. Furthermore, this review outlines potential mechanisms of action and efficacy of probiotics, prebiotics and low protein diets as a new chronic kidney disease management tool.

Gut microbiota and chronic kidney disease: evidences and mechanisms that mediate a new communication in the gastrointestinal-renal axis

Chronic kidney disease (CKD) represents a growing public health problem associated with loss of kidney function and cardiovascular disease (CVD), the main leading cause of morbidity and mortality in CKD. It is well established that CKD is associated with gut dysbiosis. Over the past few years, there has been a growing interest in studying the composition of the gut microbiota in patients with CKD as well as the mechanisms by which gut dysbiosis contributes to CKD progression, in order to identify possible therapeutic targets to improve the morbidity and survival in CKD. The purpose of this review is to explore the clinical evidence and the mechanisms involved in the gut-kidney crosstalk as well as the possible interventions to restore a normal balance of the gut microbiota in CKD. It is well known that the influence of the gut microbiota on the gut-kidney axis acts in a reciprocal way: on the one hand, CKD significantly modifies the composition and functions of the gut microbiota. On the other hand, gut microbiota is able to manipulate the processes leading to CKD onset and progression through inflammatory, endocrine, and neurologic pathways. Understanding the complex interaction between these two organs (gut microbiota and kidney) may provide novel nephroprotective interventions to prevent the progression of CKD by targeting the gut microbiota. The review is divided into three main sections: evidences from clinical studies about the existence of a gut microbiota dysbiosis in CKD; the complex mechanisms that explain the bidirectional relationship between CKD and gut dysbiosis; and reports regarding the effects of prebiotic, probiotic, and synbiotic supplementation to restore gut microbiota balance in CKD.

Inflammation in Renal Diseases: New and Old Players

Inflammation, a process intimately linked to renal disease, can be defined as a complex network of interactions between renal parenchymal cells and resident immune cells, such as macrophages and dendritic cells, coupled with recruitment of circulating monocytes, lymphocytes, and neutrophils. Once stimulated, these cells activate specialized structures such as Toll-like receptor and Nod-like receptor (NLR). By detecting danger-associated molecules, these receptors can set in motion major innate immunity pathways such as nuclear factor ĸB (NF-ĸB) and NLRP3 inflammasome, causing metabolic reprogramming and phenotype changes of immune and parenchymal cells and triggering the secretion of a number of inflammatory mediators that can cause irreversible tissue damage and functional loss. Growing evidence suggests that this response can be deeply impacted by the crosstalk between the kidneys and other organs, such as the gut. Changes in the composition and/or metabolite production of the gut microbiota can influence inflammation, oxidative stress, and fibrosis, thus offering opportunities to positively manipulate the composition and/or functionality of gut microbiota and, consequentially, ameliorate deleterious consequences of renal diseases. In this review, we summarize the most recent evidence that renal inflammation can be ameliorated by interfering with the gut microbiota through the administration of probiotics, prebiotics, and postbiotics. In addition to these innovative approaches, we address the recent discovery of new targets for drugs long in use in clinical practice. Angiotensin II receptor antagonists, NF-ĸB inhibitors, thiazide diuretics, and antimetabolic drugs can reduce renal macrophage infiltration and slow down the progression of renal disease by mechanisms independent of those usually attributed to these compounds. Allopurinol, an inhibitor of uric acid production, has been shown to decrease renal inflammation by limiting activation of the NLRP3 inflammasome. So far, these protective effects have been shown in experimental studies only. Clinical studies will establish whether these novel strategies can be incorporated into the arsenal of treatments intended to prevent the progression of human disease.

Impact of Gut Microbiota Composition on Onset and Progression of Chronic Non-Communicable Diseases

In recent years, mounting scientific evidence has emerged regarding the evaluation of the putative correlation between the gut microbiota composition and the presence of chronic non-communicable diseases (NCDs), such as diabetes mellitus, chronic kidney disease, and arterial hypertension. The aim of this narrative review is to examine the current literature with respect to the relationship between intestinal dysbiosis and the insurgence/progression of chronic NCDs, analyzing the physiopathological mechanisms that can induce microbiota modification in the course of these pathologies, and the possible effect induced by microbiota alteration upon disease onset. Therapy based on probiotics, prebiotics, synbiotics, postbiotics, and fecal microbiota transplant can represent a useful therapeutic tool, as has been highlighted on animal studies. To this moment, clinical studies that intended to demonstrate the beneficial effect induced by this kind of oral supplementation on the gut microbiota composition, and subsequent amelioration of signs and symptoms of chronic NCDs have been conducted on limited sample populations for a limited follow-up period. Therefore, to fully evaluate the therapeutic value of this kind of intervention, it would be ideal to design ample population; randomized clinical trials with a lengthy follow up period.

Impact of Gut Dysbiosis on Neurohormonal Pathways in Chronic Kidney Disease

Chronic kidney disease (CKD) is a worldwide major health problem. Traditional risk factors for CKD are hypertension, obesity, and diabetes mellitus. Recent studies have identified gut dysbiosis as a novel risk factor for the progression CKD and its complications. Dysbiosis can worsen systemic inflammation, which plays an important role in the progression of CKD and its complications such as cardiovascular diseases. In this review, we discuss the beneficial effects of the normal gut microbiota, and then elaborate on how alterations in the biochemical environment of the gastrointestinal tract in CKD can affect gut microbiota. External factors such as dietary restrictions, medications, and dialysis further promote dysbiosis. We discuss the impact of an altered gut microbiota on neuroendocrine pathways such as the hypothalamus⁻pituitary⁻adrenal axis, the production of neurotransmitters and neuroactive compounds, tryptophan metabolism, and the cholinergic anti-inflammatory pathway. Finally, therapeutic strategies including diet modification, intestinal alpha-glucosidase inhibitors, prebiotics, probiotics and synbiotics are reviewed.

Effects of Probiotics on Inflammation and Uremic Toxins Among Patients on Dialysis: A Systematic Review and Meta-Analysis

BACKGROUND/OBJECTIVES

We performed this systematic review and meta-analysis to evaluate effects of probiotics on inflammation, uremic toxins, and gastrointestinal (GI) symptoms in end-stage renal disease (ESRD) patients.

METHODS

A literature search was conducted utilizing MEDLINE, EMBASE, and Cochrane Database from inception through October 2017. We included studies that assessed assessing effects of probiotics on inflammatory markers, protein-bound uremic toxins (PBUTs), and GI symptoms in ESRD patients on dialysis. Effect estimates from the individual study were extracted and combined utilizing random effect, generic inverse variance method of DerSimonian and Laird. The protocol for this meta-analysis is registered with PROSPERO; No. CRD42017082137.

RESULTS

Seven clinical trials with 178 ESRD patients were enrolled. There was a significant reduction in serum C-reactive protein (CRP) from baseline to post-probiotic course (≥ 2 months after treatment) with standardized mean difference (SMD) of - 0.42 (95% CI - 0.68 to - 0.16, p = 0.002). When compared to control, patients who received probiotics also had a significant higher degree of reduction in CRP level with SMDs of - 0.37 (95% CI - 0.72 to 0.03, p = 0.04). However, there were no significant changes in serum TNF-alpha or albumin with SMDs of - 0.32 (95% CI - 0.92 to 0.28, p = 0.29) and 0.16 (95% CI - 0.20 to 0.53, p = 0.39), respectively. After probiotic course, there were also significant decrease in PBUTs and improvement in overall GI symptoms (reduction in GI symptom scores) with SMDs of - 0.61 (95% CI - 1.16 to - 0.07, p = 0.03) and - 1.04 (95% CI - 1.70 to - 0.38, p = 0.002), respectively.

CONCLUSION

Our study demonstrates potential beneficial effects of probiotics on inflammation, uremic toxins, and GI Symptoms in ESRD patients. Future large-scale clinical studies are required to assess its benefits on other important clinical outcomes including patient mortality.

Urea and chronic kidney disease: the comeback of the century? (in uraemia research)

Urea, a marker of uraemic retention in chronic kidney disease (CKD) and of adequacy of intradialytic solute removal, has traditionally been considered to be biologically inert. However, a number of recent experimental data suggest that urea is toxic at concentrations representative for CKD. First of all, at least five studies indicate that urea itself induces molecular changes related to insulin resistance, free radical production, apoptosis and disruption of the protective intestinal barrier. Second, urea is at the origin of the generation of cyanate, ammonia and carbamylated compounds, which as such all have been linked to biological changes. Especially carbamylation has been held responsible for post-translational protein modifications that are involved in atherogenesis and other functional changes. In observational clinical studies, these carbamylated compounds were associated with cardiovascular and overall morbidity and mortality. These findings shed new light on the validity of Kt/Vurea as a marker of dialysis adequacy. Yet, also the views that the kinetics of urea are not representative of the kinetics of several other uraemic retention solutes, and that urea cannot be held responsible for all complex metabolic and clinical changes responsible for the uraemic syndrome, still remain valid. Future efforts to improve the outcome of patients with CKD might be directed at further improving removal of solutes implied in the uraemic syndrome, including but not restricted to urea, also taking into account the impact of the intestine and (residual) renal function on solute concentration.

Inflammation-Related Mechanisms in Chronic Kidney Disease Prediction, Progression, and Outcome

Persistent, low-grade inflammation is now considered a hallmark feature of chronic kidney disease (CKD), being involved in the development of all-cause mortality of these patients. Although substantial improvements have been made in clinical care, CKD remains a major public health burden, affecting 10–15% of the population, and its prevalence is constantly growing. Due to its insidious nature, CKD is rarely diagnosed in early stages, and once developed, its progression is unfortunately irreversible. There are many factors that contribute to the setting of the inflammatory status in CKD, including increased production of proinflammatory cytokines, oxidative stress and acidosis, chronic and recurrent infections, altered metabolism of adipose tissue, and last but not least, gut microbiota dysbiosis, an underestimated source of microinflammation. In this scenario, a huge step forward was made by the increasing progression of omics approaches, specially designed for identification of biomarkers useful for early diagnostic and follow-up. Recent omics advances could provide novel insights in deciphering the disease pathophysiology; thus, identification of circulating biomarker panels using state-of-the-art proteomic technologies could improve CKD early diagnosis, monitoring, and prognostics. This review aims to summarize the recent knowledge regarding the relationship between inflammation and CKD, highlighting the current proteomic approaches, as well as the inflammasomes and gut microbiota dysbiosis involvement in the setting of CKD, culminating with the troubling bidirectional connection between CKD and renal malignancy, raised on the background of an inflammatory condition.

Gut microbiota and chronic kidney disease: implications for novel mechanistic insights and therapeutic strategies

The complicated communities of microbiota colonizing the human gastrointestinal tract exert a strong function in health maintenance and disease prevention. Indeed, accumulating evidence has indicated that the intestinal microbiota plays a key role in the pathogenesis and development of chronic kidney disease (CKD). Modulation of the gut microbiome composition in CKD may contribute to the accumulation of gut-derived uremic toxins, high circulating level of lipopolysaccharides and immune deregulation, all of which play a critical role in the pathogenesis of CKD and CKD-associated complications. In this review, we discuss the recent findings on the potential impact of gut microbiota in CKD and the underlying mechanisms by which microbiota can influence kidney diseases and vice versa. Additionally, the potential efficacy of pre-, pro- and synbiotics in the restoration of healthy gut microbia is described in detail to provide future directions for research.

Current status of the microbiome in renal transplantation

PURPOSE OF REVIEW

An imbalance between pathogenic and protective microbiota characterizes dysbiosis. Presence of dysbiosis may affect immunity, tolerance, or disease depending on a variety of conditions. In the transplant patient population, the need for immunosuppression and widespread use of prophylactic and therapeutic antimicrobial agents create new posttransplant microbiota communities that remain to be fully defined.

RECENT FINDINGS

Studies in mice have demonstrated significant bidirectional interactions between microbiota-derived products and host immune cells. The stimulation of regulatory T cell and T helper cell type 17 cells by specific products leads to maintenance of immune homeostasis versus activation of inflammation, respectively. Dysbiosis may lead to development of antigen cross-reactivity, which may affect alloreactivity. Certain immunologic sequelae of microbiota are pronounced in chronic kidney disease, because of uremia and renal metabolism of microbiota metabolites. Dietary modifications, probiotics, and fecal microbiota transplant have been investigated for alteration of microbiota in humans.

SUMMARY

Researchers have begun to identify dysbioses associated with clinical conditions, including chronic kidney disease, posttransplant infection, and rejection. This information will allow clinicians not only to select at-risk patients for early intervention, but also to develop therapies that restore the microbiota to a state of homeostasis or tolerance.

Probiotic Supplementation in Chronic Kidney Disease: A Double-blind, Randomized, Placebo-controlled Trial

OBJECTIVE

The objective of the study was to evaluate the effects of probiotic supplementation on the gut microbiota profile and inflammatory markers in chronic kidney disease patients undergoing maintenance hemodialysis (HD).

DESIGN AND METHODS

This was a randomized, double-blind, placebo-controlled study. Forty-six HD patients were assigned to receive 1 of 2 treatments: probiotic (n = 23; Streptococcus thermophilus, Lactobacillus acidophilus e Bifidobacterialongum, 90 billion colony-forming units per day) or placebo (n = 23) daily for 3 months. Blood and feces were collected at baseline and after intervention. The inflammatory markers (C-reactive protein and interleukin-6) were analyzed by immunoenzymatic assay (enzyme-linked immunosorbent assay). Uremic toxins plasma levels (indoxyl sulfate, p-cresyl sulfate, and indole-3-acetic acid) were obtained by Reversed-Phase High-Performance Liquid Chromatography. Routine laboratory parameters were measured by standard techniques. Fecal pH was measured by the colorimetric method, and the gut microbiota profile was assessed by Denaturing Gradient Gel Electrophoresis analysis.

RESULTS

Sixteen patients remained in the probiotic group (11 men, 53.6 ± 11.0 year old, 25.3 ± 4.6 kg/m²) and 17 in the placebo group (10 men, 50.3 ± 8.5 year old, 25.2 ± 5.7 kg/m²). After probiotic supplementation there was a significant increase in serum urea (from 149.6 ± 34.2 mg/dL to 172.6 ± 45.0 mg/dL, P = .02), potassium (from 4.4 ± 0.4 mmol/L to 4.8 ± 0.4 mmol/L, P = .02), and indoxyl sulfate (from 31.2 ± 15.9 to 36.5 ± 15.0 mg/dL, P = .02). The fecal pH was reduced from 7.2 ± 0.8 to 6.5 ± 0.5 (P = .01). These parameters did not change significantly in placebo group. Changes in the percentage delta (Δ) between groups were exhibited with no statistical differences observed. The inflammatory markers and gut profile were not altered by supplementation.

CONCLUSIONS

Aprobiotic supplementation failed to reduce uremic toxins and inflammatory markers. Therefore, probiotic therapy should be chosen with caution in HD patients. Further studies addressing probiotic therapy in chronic kidney disease patients are needed.

Depletion of Gut Microbiota Protects against Renal Ischemia-Reperfusion Injury

An accumulating body of evidence shows that gut microbiota fulfill an important role in health and disease by modulating local and systemic immunity. The importance of the microbiome in the development of kidney disease, however, is largely unknown. To study this concept, we depleted gut microbiota with broad-spectrum antibiotics and performed renal ischemia-reperfusion (I/R) injury in mice. Depletion of the microbiota significantly attenuated renal damage, dysfunction, and remote organ injury and maintained tubular integrity after renal I/R injury. Gut flora-depleted mice expressed lower levels of F4/80 and chemokine receptors CX3CR1 and CCR2 in the F4/80⁺ renal resident macrophage population and bone marrow (BM) monocytes than did control mice. Additionally, compared with control BM monocytes, BM monocytes from gut flora-depleted mice had decreased migratory capacity toward CX3CL1 and CCL2 ligands. To study whether these effects were driven by depletion of the microbiota, we performed fecal transplants in antibiotic-treated mice and found that transplant of fecal material from an untreated mouse abolished the protective effect of microbiota depletion upon renal I/R injury. In conclusion, we show that depletion of gut microbiota profoundly protects against renal I/R injury by reducing maturation status of F4/80⁺ renal resident macrophages and BM monocytes. Therefore, dampening the inflammatory response by targeting microbiota-derived mediators might be a promising therapy against I/R injury.

Gut microbiota in renal physiology: focus on short-chain fatty acids and their receptors

A number of recent studies have begun to explore a new and exciting area: the interaction between the gut microbiome and renal physiology. In particular, multiple studies have focused on the role of microbially produced short chain fatty acids, which are generally thought to promote health. This review will focus on what is known to date regarding the influence of the microbiome on renal function, with emphasis on the cell biology, physiology, and clinical implications of short chain fatty acids and short chain fatty acid receptors. It is clear that microbe-host interactions are an exciting and ever-expanding field, which has implications for how we view diseases such as hypertension, acute kidney injury, and chronic kidney disease. However, it is important to recognize that although the potential promise of this area is extremely enticing, we are only the very edge of this new field.

Gut Microbiome and Kidney Disease in Pediatrics: Does Connection Exist?

Child development is a unique and continuous process that is impacted by genetics and environmental factors. Gut microbiome changes with development and depends on the stage of gut maturation, nutrition, and overall health. In spite of emerging data and active study in adults, the gut-renal axis in pediatrics has not been well considered and investigated. This review will focus on the current knowledge of gut microbiota impacts on kidney disease with extrapolation to the pediatric population.

The Role of the Gut Microbiome on Chronic Kidney Disease

Chronic kidney disease (CKD) is estimated to affect nearly 500 million people worldwide and cardiovascular (CV) disease is a major cause of death in this population. However, therapeutic interventions targeting traditional CV risks are not effective at lowering the incidence of CV events or at delaying the progression of the disease in CKD patients. In recent years, disturbances of normal gut microbiome were recognized in the pathogenesis of diverse chronic diseases. Gut dysbiosis is being unraveled in CKD and pointed as a nontraditional risk factor for CV risk and CKD progression. The most often reported changes in gut microbiome in CKD are related to the lower levels of Bifidobacteriaceae and Lactobacillaceae and to higher levels of Enterobacteriaceae. Although metagenomics brought us an amplified vision on the microbial world that inhabits the human host, it still lacks the sensitivity to characterize the microbiome up to species level, not revealing alterations that occur within specific genus. Here, we review the current state-of-the-art concerning gut dysbiosis in CKD and its role in pathophysiological mechanisms in CKD, particularly in relation with CV risk. Also, the strategies towards prevention and treatment of gut dysbiosis in CKD progression will be discussed.

Probiotics and chronic kidney disease

Probiotics are the focus of a thorough investigation as a natural biotreatment due to their various health-promoting effects and inherent ability to fight specific diseases including chronic kidney disease (CKD). Indeed, intestinal microbiota has recently emerged as an important player in the progression and complications of CKD. Because many of the multifactorial physiological functions of probiotics are highly strain specific, preselection of appropriate probiotic strains based on their expression of functional biomarkers is critical. The interest in developing new research initiatives on probiotics in CKD have increased over the last decade with the goal of fully exploring their therapeutic potentials. The efficacy of probiotics to decrease uremic toxin production and to improve renal function has been investigated in in vitro models and in various animal and human CKD studies. However to date, the quality of intervention trials investigating this novel CKD therapy is still lacking. This review outlines potential mechanisms of action and efficacy of probiotics as a new CKD management tool, with a particular emphasis on uremic toxin production and inflammation.

The effect of probiotics on serum levels of cytokine and endotoxin in peritoneal dialysis patients: a randomised, double-blind, placebo-controlled trial

Inflammatory markers such as interleukin (IL)-6 and tumour necrosis factor-alpha (TNF-α) are elevated in dialysis patients and can predict cardiovascular events and all-cause mortality. Endotoxin is an important source and also another marker of inflammation in patients with chronic kidney disease. The aim of this study was to evaluate the impact of oral probiotics on serum levels of endotoxemia and cytokines in peritoneal dialysis (PD) patients. The decline of residual renal function, peritonitis episodes, and cardiovascular events were also recorded. From July 2011 to June 2012, a randomised, double-blind, placebo-controlled trial was conducted in PD patients. The intervention group received one capsule of probiotics containing 10(9) cfu Bifobacterium bifidum A218, 10(9) cfu Bifidobacterium catenulatum A302, 10(9) cfu Bifidobacterium longum A101, and 10(9) cfu Lactobacillus plantarum A87 daily for six months, while the placebo group received similar capsules containing maltodextrin for the same duration. Levels of serum TNF-α, interferon gamma, IL-5, IL-6, IL-10, IL-17, and endotoxin were measured before and six months after intervention. 39 patients completed the study (21 in the probiotics group and 18 in the placebo group). In patients receiving probiotics, levels of serum TNF-α, IL-5, IL-6, and endotoxin significantly decreased after six months of treatment, while levels of serum IL-10 significantly increased. In contrast, there were no significant changes in levels of serum cytokines and endotoxin in the placebo group after six months. In addition, the residual renal function was preserved in patients receiving probiotics. In conclusion, probiotics could significantly reduce the serum levels of endotoxin, pro-inflammatory cytokines (TNF-α and IL-6), IL-5, increase the serum levels of anti-inflammatory cytokine (IL-10), and preserve residual renal function in PD patients.

The intestine and the kidneys: a bad marriage can be hazardous

The concept that the intestine and chronic kidney disease influence each other, emerged only recently. The problem is multifaceted and bidirectional. On one hand, the composition of the intestinal microbiota impacts uraemic retention solute production, resulting in the generation of essentially protein-bound uraemic toxins with strong biological impact such as vascular damage and progression of kidney failure. On the other hand, the uraemic status affects the composition of intestinal microbiota, the generation of uraemic retention solutes and their precursors and causes disturbances in the protective epithelial barrier of the intestine and the translocation of intestinal microbiota into the body. All these elements together contribute to the disruption of the metabolic equilibrium and homeostasis typical to uraemia. Several measures with putative impact on intestinal status have recently been tested for their influence on the generation or concentration of uraemic toxins. These include dietary measures, prebiotics, probiotics, synbiotics and intestinal sorbents. Unfortunately, the quality and the evidence base of many of these studies are debatable, especially in uraemia, and often results within one study or among studies are contradictory. Nevertheless, intestinal uraemic metabolite generation remains an interesting target to obtain in the future as an alternative or additive to dialysis to decrease uraemic toxin generation. In the present review, we aim to summarize (i) the role of the intestine in uraemia by producing uraemic toxins and by generating pathophysiologically relevant changes, (ii) the role of uraemia in modifying intestinal physiology and (iii) the therapeutic options that could help to modify these effects and the studies that have assessed the impact of these therapies.

Toward the comprehensive understanding of the gut ecosystem via metabolomics-based integrated omics approach

Recent advances in DNA sequencing and mass spectrometry technologies have allowed us to collect more data on microbiome and metabolome to assess the influence of the gut microbiota on human health at a whole-systems level. Major advances in metagenomics and metabolomics technologies have shown that the gut microbiota contributes to host overall health status to a large extent. As such, the gut microbiota is often likened to a measurable and functional organ consisting of prokaryotic cells, which creates the unique gut ecosystem together with the host eukaryotic cells. In this review, we discuss in detail the relationship between gut microbiota and its metabolites like choline, bile acids, phenols, and short-chain fatty acids in the host health and etiopathogenesis of various pathological states such as multiple sclerosis, autism, obesity, diabetes, and chronic kidney disease. By integrating metagenomic and metabolomic information on a systems biology-wide approach, we would be better able to understand this interplay between gut microbiome and host metabolism. Integration of the microbiome, metatranscriptome, and metabolome information will pave the way toward an improved holistic understanding of the complex mammalian superorganism. Through the modeling of metabolic interactions between lifestyle, diet, and microbiota, integrated omics-based understanding of the gut ecosystem is the new avenue, providing exciting novel therapeutic approaches for optimal host health.

Intestinal microbiota-kidney cross talk in acute kidney injury and chronic kidney disease

The pathophysiology of acute kidney injury (AKI) involves multiple and overlapping immunological, biochemical, and hemodynamic mechanisms that modulate the effects of both the initial insult and the subsequent repair. Limited but recent experimental data have revealed that the intestinal microbiota significantly affects outcomes in AKI. Additional evidence shows significant changes in the intestinal microbiota in chronic kidney disease patients and in experimental AKI. In this minireview, we discuss the current status of the effect of intestinal microbiota on kidney diseases, the immunomodulatory effects of intestinal microbiota, and the potential mechanisms by which microbiota can modify kidney diseases and vice versa. We also propose future studies to clarify the role of intestinal microbiota in kidney diseases and to explore how the modification of gut microbiota may be a potential therapeutic tool.

Randomized controlled trial of strain-specific probiotic formulation (Renadyl) in dialysis patients

BACKGROUND

Primary goal of this randomized, double-blind, placebo-controlled crossover study of Renadyl in end-stage renal disease patients was to assess the safety and efficacy of Renadyl measured through improvement in quality of life or reduction in levels of known uremic toxins. Secondary goal was to investigate the effects on several biomarkers of inflammation and oxidative stress.

METHODS

Two 2-month treatment periods separated by 2-month washout and crossover, with physical examinations, venous blood testing, and quality of life questionnaires completed at each visit. Data were analyzed with SAS V9.2.

RESULTS

22 subjects (79%) completed the study. Observed trends were as follows (none reaching statistical significance): decline in WBC count (-0.51 × 10(9)/L, P = 0.057) and reductions in levels of C-reactive protein (-8.61 mg/L, P = 0.071) and total indoxyl glucuronide (-0.11 mg%, P = 0.058). No statistically significant changes were observed in other uremic toxin levels or measures of QOL.

CONCLUSIONS

Renadyl appeared to be safe to administer to ESRD patients on hemodialysis. Stability in QOL assessment is an encouraging result for a patient cohort in such advanced stage of kidney disease. Efficacy could not be confirmed definitively, primarily due to small sample size and low statistical power-further studies are warranted.

Lactobacillus bulgaricus mutants decompose uremic toxins

BACKGROUND/AIMS

We aim to obtain a probiotic strain from Lactobacillus bulgaricus by testing its capability to decompose uremic toxins to provide new intestinal bacteria for the treatment of chronic renal failure.

METHODS

Original L. bulgaricus was cultured with the serum of uremic patients and then mutated by physical (ultraviolet) and chemical (diethyl sulfate) methods repeatedly. Using creatinine decomposition rate as an observed index, we selected the best strains which decreased the most concentration of the creatinine. We then tested its ability to decompose urea, uric acid, serum phosphate, parathyroid hormone, and homocysteine and its genetic stability.

RESULTS

After inductive and mutagenic treatment, DUC3-17 was selected. Its decomposition rate of creatinine, urea nitrogen, uric acid, phosphorus, parathyroid hormone, and homocysteine were 17.23%, 36.02%, 9.84%, 15.73%, 78.26%, and 12.69%, respectively. The degrading capacity was sustained over five generations.

CONCLUSIONS

After directional induction and compound mutation, L. bulgaricus has greater capacity to decompose uremic toxins, with a stable inheritance.

Protein-bound uremic toxins: new culprits of cardiovascular events in chronic kidney disease patients

Chronic kidney disease (CKD) has been considered a major risk factor for cardiovascular diseases. Although great advances have recently been made in the pathophysiology and treatment of cardiovascular diseases, CKD remains a major global health problem. Moreover, the occurrence rates of cardiovascular events among CKD patients increase even in cases in which patients undergo hemodialysis, and the mechanisms underlying the so-called “cardiorenal syndrome” are not clearly understood. Recently, small-molecule uremic toxins have been associated with cardiovascular mortality in CKD and/or dialysis patients. These toxins range from small uncharged solutes to large protein-bound structures. In this review, we focused on protein-bound uremic toxins, such as indoxyl sulfate and p-cresyl sulfate, which are poorly removed by current dialysis techniques. Several studies have demonstrated that protein-bound uremic toxins, especially indoxyl sulfate, induce vascular inflammation, endothelial dysfunction, and vascular calcification, which may explain the relatively poor prognosis of CKD and dialysis patients. The aim of this review is to provide novel insights into the effects of indoxyl sulfate and p-cresyl sulfate on the pathogenesis of atherosclerosis.