Short-chain fatty acids: a link between prebiotics and microbiota in chronic kidney disease

Dietary mung bean as promising food for human health: gut microbiota modulation and insight into factors, regulation, mechanisms and therapeutics-an update

Plant-based functional foods have gained wider attention in current scenario with mung bean harboring several bioactive compounds with promising gut health benefits and pharmacological importance. Consumption of mung bean has a positive impact on beneficial gut microbes and microbial metabolite production. The effects of dietary mung bean on gut microbial homeostasis and the management of gut-related diseases along with the possible mechanism of action, have been highlighted through this review paving a way for a promising role of dietary mung bean as a functional food in the management of gut-related diseases for example mung bean peptides can help not only in treating prediabetes but also delaying the aging process by targeting the intestinal microflora. In addition, expanding our knowledge of how diets affect host health and disease, including the effects of mung bean dietary components on gut microbiota-derived metabolites, will eventually allow for the development of tailored diets and nutrients.

Production of Toxins by the Gut Microbiota: The Role of Dietary Protein

PURPOSE OF REVIEW

This narrative review will discuss how the intake of specific protein sources (animal and vegetable) providing specific amino acids can modulate the gut microbiota composition and generate toxins. A better understanding of these interactions could lead to more appropriate dietary recommendations to improve gut health and mitigate the risk of complications promoted by the toxic metabolites formed by the gut microbiota.

RECENT FINDINGS

Gut microbiota is vital in maintaining human health by influencing immune function and key metabolic pathways. Under unfavorable conditions, the gut microbiota can produce excess toxins, which contribute to inflammation and the breakdown of the integrity of the intestinal barrier. Genetic and environmental factors influence gut microbiota diversity, with diet playing a crucial role. Emerging evidence indicates that the gut microbiota significantly metabolizes amino acids from dietary proteins, producing various metabolites with beneficial and harmful effects. Amino acids such as choline, betaine, l-carnitine, tyrosine, phenylalanine, and tryptophan can increase the production of uremic toxins when metabolized by intestinal bacteria. The type of food source that provides these amino acids affects the production of toxins. Plant-based diets and dietary fiber are associated with lower toxin formation than animal-based diets due to the high amino acid precursors in animal proteins.

The effect of canagliflozin on gut microbiota and metabolites in type 2 diabetic mice

BACKGROUND

Sodium glucose cotransporter 2 inhibitor (SGLT2i) represent a new type of hypoglycemic medicine that can cause massive loss of glucose from the urine, which have several benefits of reducing body weight and improving the prognosis of cardiovascular and kidney diseases. Although they are oral medicated hypoglycemic agents, their effects on the gut microbiome and function have been unclear.

OBJECTIVE

In order to describe the effects of canagliflozin on intestinal flora and metabolites, diabetic mice were randomized to receive canagliflozin or isoconcentration carboxymethylcellulose sodium by gavage for 8 weeks. Feces were collected for 16 S rRNA gene and LC-MS/MS analysis and enriched metabolic pathways through Kyoto Encyclopedia of Genes and Genomes (KEGG). Liver, muscle, intestinal, fat were collected for qRT-PCR according to KEGG enriched metabolic pathways.

RESULTS

Our results showed that canagliflozin significantly increased GLP-1 level and impacted on the composition of gut microbiota and metabolites. It mainly increased Muribaculum, Ruminococcaceae_UCG_014, Lachnospiraceae-UCG-001, decreased ursodeoxycholic acids (UDCA) and hyodeoxycholic acids (HDCA), and increased fatty acids metabolites in feces.

CONCLUSION

In conclusion, we analyzed the changes of intestinal microbial composition and metabolites in diabetic mice after canagliflozin intervention and found that canagliflozin influenced intestinal fatty acid and bile acid (BA) metabolism. This study will provide reference for subsequent SGLT2i and intestinal related research.

Development and validation of derivatization-based LC-MS/MS method for quantification of short-chain fatty acids in human, rat, and mouse plasma

Short-chain fatty acids (SCFAs), the end products of gut microbial fermentation of dietary fibers and non-digestible polysaccharides, act as a link between the microbiome, immune system, and inflammatory processes. The importance of accurately quantifying SCFAs in plasma has recently emerged to understand their biological role. In this work, a sensitive and reproducible LC-MS/MS method is reported for SCFAs quantification in three different matrices such as human, rat and mouse plasma via derivatization, using as derivatizing agent O-benzylhydroxylamine (O-BHA), coupled with liquid-liquid extraction. First, the instrumental parameters of the mass spectrometer and then the chromatographic conditions were optimized using previously SCFAs derivatives synthetized and used as standards. After that, the best conditions for derivatization and extraction from plasma were studied and a series of determinations were performed on human, rat, and mouse plasma aliquots to validate the overall method (derivatization, extraction, and LC-MS/MS determination). The method showed good performance in terms of recovery (> 80%), precision (RSD <14%), accuracy (RE < ± 10%) and sensitivity (LOQ of 0.01 µM for acetic, butyric, propionic and isobutyric acid) in all plasma samples. The method thus developed and validated was applied to the quantification of major SCFAs in adult and aged mice, germ-free mice and in germ-free recipient mice subjected to fecal transplant from adult and aged donors. Results highlighted how plasma concentrations of SCFAs are correlated with age further highlighting the importance of developing a method that is reliable for the quantification of SCFAs to study their biological role.

Diet-mediated gut microbial community modulation and signature metabolites as potential biomarkers for early diagnosis, prognosis, prevention and stage-specific treatment of colorectal cancer

BACKGROUND

Over the last decade, studies have shown an increased incidence of colorectal cancer (CRC), particularly early onset colorectal cancer (EOCRC). Researchers have demonstrated that dietary behavior, especially among young adults, influences alterations in the gut microbial community, leading to an increased accumulation of pathogenic gut microbiota and a decrease in beneficial ones. Unfortunately, CRC is likely to be diagnosed at a late stage, increasing CRC-related mortality. However, this alteration in the gut microbiota (gut dysbiosis) can be harnessed as a biomarker for non-invasive diagnosis, prognosis, prevention, and treatment of CRC in an effort to prevent late diagnosis and poor prognosis associated with CRC.

AIM OF REVIEW

This review discusses identification of potential biomarkers by targeting diet-mediated gut dysbiosis for the stage-specific diagnosis, prognosis, treatment, and prevention of CRC. Our findings provide a comprehensive insight into the potential of protumorigenic bacteria (e.g.pathogenic Escherichia coli,enterotoxigenic Bacteroides fragilis and Fusobacterium nucleatum) and their metabolites (e.g., colibactin and B. fragilis toxin) from gut dysbiosis as biomarkers for the diagnosis of CRC.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Collectively, a detailed understanding of the available data from current studies suggests that, further research on quantification of metabolites and stage-specific pathogenic microbial abundance is required for the diagnosis and treatment of CRC based on microbial dysbiosis. Specifically, future studies on faecal samples, from patient with CRC, should be conducted for F. nucleatum among different opportunistic bacteria, given its repeated occurrence in faecal samples and CRC biopsies in numerous studies. Finally, we discuss the potential of faecal microbial transplantation (FMT) as an intervention to restore damaged gut microbiota during CRC treatment and management.

Gut Microbiota Interventions to Retain Residual Kidney Function

Residual kidney function for patients with chronic kidney disease (CKD) is associated with better quality of life and outcome; thus, strategies should be implemented to preserve kidney function. Among the multiple causes that promote kidney damage, gut dysbiosis due to increased uremic toxin production and endotoxemia need attention. Several strategies have been proposed to modulate the gut microbiota in these patients, and diet has gained increasing attention in recent years since it is the primary driver of gut dysbiosis. In addition, medications and faecal transplantation may be valid strategies. Modifying gut microbiota composition may mitigate chronic kidney damage and preserve residual kidney function. Although various studies have shown the influential role of diet in modulating gut microbiota composition, the effects of this modulation on residual kidney function remain limited. This review discusses the role of gut microbiota metabolism on residual kidney function and vice versa and how we could preserve the residual kidney function by modulating the gut microbiota balance.

FTZ polysaccharides ameliorate kidney injury in diabetic mice by regulating gut-kidney axis

BACKGROUND

The Fufang-zhenzhu-tiaozhi formula (FTZ), a traditional Chinese medicine (TCM) commonly used to treat metabolic diseases, potentially impacts the microbial ecosystem. Increasing evidence suggests that polysaccharides, bioactive components of TCMs, have great potential on kinds of diseases such as DKD by regulating intestinal flora.

PURPOSE

This study aimed to investigate whether the polysaccharide components in FTZ (FTZPs) have beneficial effects in DKD mice via the gut-kidney axis.

STUDY DESIGN AND METHODS

The DKD model in mice was established by streptozotocin combined with a high-fat diet (STZ/HFD). Losartan was used as a positive control, and FTZPs were administered at doses of 100 and 300 mg/kg daily. Renal histological changes were measured by H&E and Masson staining. Western blotting, quantitative real-time polymerase chain reaction (q-PCR) and immunohistochemistry were performed to analyze the effects of FTZPs on renal inflammation and fibrosis, which were further confirmed using RNA sequencing. Immunofluorescence was used to analyze the effects of FTZPs on colonic barrier function in DKD mice. Faecal microbiota transplantation (FMT) was used to evaluate the contribution of intestinal flora. 16S rRNA sequencing was utilized to analyze the composition of intestinal bacteria, and UPLC-QTOF-MS-based untargeted metabolomics was used to identify the metabolite profiles.

RESULTS

Treatment with FTZPs attenuated kidney injury, as indicated by the decreased urinary albumin/creatinine ratio and improved renal architecture. FTZPs downregulated the expression of renal genes associated with inflammation, fibrosis, and systematically blunted related pathways. FTZPs also restored the colonic mucosal barrier and increased the expression of tight junction proteins (E-cadherin). The FMT experiment confirmed the substantial contribution of the FTZPs-reshaped microbiota to relieving DKD symptoms. Moreover, FTZPs elevated the content of short-chain fatty acids (propionic acid and butanoic acid) and increased the level of the SCFAs transporter Slc22a19. Intestinal flora disorders caused by diabetes, including the growth of the genera Weissella, Enterococcus and Akkermansia, were inhibited by FTZPs treatment. Spearman's analysis revealed that these bacteria were positively correlated with indicators of renal damage.

CONCLUSION

These results show that oral administration of FTZPs, by altering SCFAs levels and the gut microbiome, is a therapeutic strategy for the treatment of DKD.

Effects of prebiotics on intestinal physiology, neuropsychological function, and exercise capacity of mice with sleep deprivation

People suffered from insufficient or disrupted sleep due to night shifts, work pressure, and irregular lifestyles. Sleep deprivation caused by inadequate quantity or quality of sleep has been associated with not only increased risk of metabolic diseases, gut dysbiosis, and emotional disorders but also decreased work and exercise performance. In this study, we used the modified multiple platform method (MMPM) to induce pathological and psychological characteristics of sleep deprivation with C57BL/6J male mice, and investigated whether supplementing a prebiotics mixture of short-chain galactooligosaccharides (scGOS) and long-chain fructooligosaccharides (lcFOS) (9:1 ratio) could improve the impacts of sleep deprivation on intestinal physiology, neuropsychological function, inflammation, circadian rhythm, and exercise capacity. Results showed that sleep deprivation caused intestinal inflammation (increased TNFA and IL1B) and decreased intestinal permeability with a significant decrease in the tight junction genes (OCLN, CLDN1, TJP1, and TJP2) of intestine and brain. The prebiotics significantly increased the content of metabolite short-chain fatty acids (acetate and butyrate) while recovering the expression of indicated tight junction genes. In hypothalamus and hippocampus, clock (BMAL1 and CLOCK) and tight junction (OCLN and TJP2) genes were improved by prebiotics, and corticotropin-releasing hormone receptor genes, CRF1 and CRF2, were also significantly regulated for mitigation of depression and anxiety caused by sleep deprivation. Also, prebiotics brought significant benefits on blood sugar homeostasis and improvement of exercise performance. Functional prebiotics could improve physiological modulation, neuropsychological behaviors, and exercise performance caused by sleep deprivation, possibly through regulation of inflammation and circadian rhythm for health maintenance. However, the microbiota affected by prebiotics and sleep deprivation should warrant further investigation.

PREBIOTIC: a study protocol of a randomised controlled trial to assess prebiotic supplementation in kidney transplant recipients for preventing infections and gastrointestinal upset - a feasibility study

BACKGROUND

Modulating the microbiota in the large intestine of kidney transplant recipients through prebiotic supplementation may prevent infectious complications from occurring. To date, there have been no interventional trials which have investigated this novel treatment in kidney transplantation. The aim of PREBIOTIC is to assess the feasibility of performing a randomised controlled trial of prebiotics in reducing infections and gastrointestinal symptoms in kidney transplant recipients.

METHODS

Sixty kidney transplant patients will be recruited to a double-blind, placebo-controlled, randomised feasibility trial. Patients will be provided with prebiotic therapy or placebo for 4 to 6 weeks. Outcomes will include recruitment, adherence, tolerance, retention, laboratory parameters (including serum indoxyl sulphate, ρ-cresyl sulphate and stool collection), patients' self-assessed quality of life, gastrointestinal symptoms and clinical outcomes.

DISCUSSION

This trial will assess the feasibility of prebiotic supplementation in kidney transplant recipients. Prebiotics not only may alter the gut microbiota and their inherent metabolism and production of uraemic toxins but also may prevent infections from occurring in kidney transplant recipients.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry number ACTRN12618001057279p. The date of registration was 25th June 2018, https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=375370&isReview=true .

Archaea from the gut microbiota of humans: Could be linked to chronic diseases?

Archaea comprise a unique domain of organisms with distinct biochemical and genetic differences from bacteria. Methane-forming archaea, methanogens, constitute the predominant group of archaea in the human gut microbiota, with Methanobrevibacter smithii being the most prevalent. However, the effect of methanogenic archaea and their methane production on chronic disease remains controversial. As perturbation of the microbiota is a feature of chronic conditions, such as cardiovascular disease, neurodegenerative diseases and chronic kidney disease, assessing the influence of archaea could provide a new clue to mitigating adverse effects associated with dysbiosis. In this review, we will discuss the putative role of archaea in the gut microbiota in humans and the possible link to chronic diseases.

Faecal Microbiota Transplantation and Chronic Kidney Disease

Faecal microbiota transplantation (FMT) has attracted increasing attention as an intervention in many clinical conditions, including autoimmune, enteroendocrine, gastroenterological, and neurological diseases. For years, FMT has been an effective second-line treatment for Clostridium difficile infection (CDI) with beneficial outcomes. FMT is also promising in improving bowel diseases, such as ulcerative colitis (UC). Pre-clinical and clinical studies suggest that this microbiota-based intervention may influence the development and progression of chronic kidney disease (CKD) via modifying a dysregulated gut–kidney axis. Despite the high morbidity and mortality due to CKD, there are limited options for treatment until end-stage kidney disease occurs, which results in death, dialysis, or kidney transplantation. This imposes a significant financial and health burden on the individual, their families and careers, and the health system. Recent studies have suggested that strategies to reverse gut dysbiosis using FMT are a promising therapy in CKD. This review summarises the preclinical and clinical evidence and postulates the potential therapeutic effect of FMT in the management of CKD.

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.

Lactiplantibacillus plantarum J-15 reduced calcium oxalate kidney stones by regulating intestinal microbiota, metabolism, and inflammation in rats

The prevention role of Lactiplantibacillus plantarum against the formation of kidney stones has been increasingly recognized; its mechanism, however, has mainly been focused on inhibiting the inflammation in the colon in the gastrointestinal (GI) system, and the intestinal metabolites from microflora have not been revealed fully with regarding to the stone formation. In this study, we investigated the effect of L. plantarum J-15 on kidney stone formation in renal calcium oxalate (CaOx) rats induced by ethylene glycol and monitored the changes of intestinal microflora and their metabolites detected by 16S rRNA sequencing and widely targeted analysis, followed by the evaluation of the intestinal barrier function and inflammation levels in the colon, blood and kidney. The results showed that L. plantarum J-15 effectively reduced renal crystallization and urinary oxalic acid. Ten microbial genera, including anti-inflammatory and SCFAs-related Faecalibaculum, were enriched in the J-15 treatment group. There are 136 metabolites from 11 categories significantly different in the J-15 supplementation group compared with CaOx model rats, most of which were enriched in the amino acid metabolic and secondary bile acid pathways. The expression of intestinal tight junction protein Occludin and the concentration of pro-inflammatory cytokines and prostaglandin were decreased in the intestine, which further reduced the translocated lipopolysaccharide and inflammation levels in the blood upon J-15 treatment. Thus, the inflammation and injury in the kidney might be alleviated by downregulating TLR4/NF-κB/COX-2 signaling pathway. It suggested that L. plantarum J-15 might reduce kidney stone formation by restoring intestinal microflora and metabolic disorder, protecting intestinal barrier function, and alleviating inflammation. This finding provides new insights into the therapies for renal stones.

Phenylalanine Butyramide Is a New Cosmetic Ingredient with Soothing and Anti-Reddening Potential

Human skin is colonized by diverse commensal microbes, making up the skin microbiota (SM), contributing to skin integrity and homeostasis. Many of the beneficial effects aroused by the SM are exerted by microbial metabolites such as short-chain fatty acids (SCFAs), including butyric acid. The SCFAs can be used in cosmetic formulations against skin diseases to protect SM by preserving and/or restoring their natural balance. Unpleasant sensorial properties and unfavorable physico-chemical properties of butyrate strongly limit its cosmetic use. In contrast, some butyrate derivatives, including phenylalanine butyramide (C13H18N2O2, FBA), a solid form of butyric acid, are odorless while retaining the pharmacokinetic properties and safety profile of butyric acid. This study assessed the FBA's permeation across the skin and its soothing and anti-reddening potential to estimate its cosmetic application. The dosage method used to estimate FBA's levels was validated to be sure of analytical results. The FBA diffusion tests were estimated in vitro using a Franz-type vertical diffusion cell. The soothing action was evaluated in vivo by Colorimeter CL400, measuring the erythema index. The results suggest that the FBA represents an innovative way to exploit the benefits of butyric acid in the cosmetic fields since it cannot reach the bloodstream, is odorless, and has a significative soothing action (decrease the erythema index -15.7% after 30', and -17.8% after 60').

Effect of formulations and fermentation processes on volatile organic compounds and prebiotic potential of gluten-free bread fortified by spirulina (Arthrospira platensis)

Gluten free (GF) foods, designed and marketed for the needs of people who are unable to metabolize gluten, in recent years have aroused growing interest that has led to the conquest of important market segments, with a strongly growing trend. Given the low protein content of standard GF flours, it is particularly important to fortify GF foods, and to study the effect that this process exerts on functional and sensorial characteristics. In this work, fortification of GF bakery goods was done with the addition of Arthrospira platensis (spirulina) flour. Two different dough formulations (with and without fortification) were fermented by four different processes, including spontaneous, single strains and sourdough starters. The baked products were then subjected to "consumer's tests". During the process, fermentation performances, prebiotic activity, and the VOC (Volatile Organic Compound) profiles were analyzed and compared through robust multivariate statistics. The results obtained evidenced that fortification led to a product with more abundant (medium organic acids) and exclusive bioactives (thymol, borneol, and nicotinic acid), which were correlated to the prebiotic activity of spirulina breads. This work, for the first time indicates that spirulina can be used to fortify GF bakery, improving also its functional potential.

Therapeutic Effects of Prebiotics on Constipation: A Schematic Review

Constipation is a highly prevalent functional gastrointestinal disorder that may significantly affect the quality of life and health care costs. Treatment for constipation has been broadly reviewed by cognitive therapies, medications, and surgical interventions. Gut microbiota such as Bifidobacterium, Clostridium, Bacteroidetes, and Lactobacilli have been demonstrated in functional gastrointestinal disorders and prebiotics to play a role in augmenting their presence. Prebiotics are ingredients in foods that remain undigested, stimulating the bacteria. There are a variety of prebiotics; however, there exists only a handful of studies that describe their efficacy for chronic constipation. The purpose of this study is to review the available literature on the utility of different commercially available prebiotics in patients with functional and chronic idiopathic constipation. To fulfil the objectives of the study, published articles in the English language on databases such as Pubmed, Ovid Medline, and EMBASE were searched. The terms prebiotics, constipation, chronic constipation, functional constipation were used. We reviewed and included 21 randomized controlled trials exploring the role of prebiotics in constipated adults. Prebiotics are effective treatments for chronic idiopathic constipation and showed improvement in the stool consistency, number of bowel moments and bloating. Although which prebiotic formulary would promote improved symptoms of constipation is still not clear.

The Effects of Gum Acacia on the Composition of the Gut Microbiome and Plasma Levels of Short-Chain Fatty Acids in a Rat Model of Chronic Kidney Disease

Chronic kidney disease (CKD) may be fatal for its victims and is an important long-term public health problem. The complicated medical procedures and diet restrictions to which patients with CKD are subjected alter the gut microbiome in an adverse manner, favoring over-accumulation of proteolytic bacteria that produce ammonia and other toxic substances. The present study aimed to investigate the effect of GA on 1) the composition of the gut microbiome and 2) on plasma levels of short-chain fatty acids. Male Wister rats were divided into four groups (six each) and treated for 4 weeks based on the following: control, dietary adenine (0.75%, w/w) to induce CKD, GA in the drinking water (15%, w/v), and both adenine and GA. At the end of the treatment period, plasma, urine, and fecal samples were collected for determination of several biochemical indicators of renal function and plasma levels of short-chain fatty acids (SCFAs) as well as characterization of the gut microbiome. Dietary adenine induced the typical signs of CKD, i.e., loss of body weight and impairment of renal function, while GA alleviated these effects. The intestine of the rats with CKD contained an elevated abundance of pathogenic Proteobacteria, Actinobacteria, and Verrucomicrobia but lowered proportions of Lactobacillaceae belonging to the Firmicutes phylum. Plasma levels of propionate and butyrate were lowered by dietary adenine and restored by GA. A negative association (Spearman's p-value ≤ 0.01, r ≤ 0.5) was observed between Firmicutes and plasma creatinine, urea, urine N-acetyl-beta-D-glucosaminidase (NAG) and albumin. Phylum Proteobacteria on the other hand was positively associated with these markers while Phylum Bacteroidetes was positively associated with plasma SCFAs. In conclusion, the adverse changes in the composition of the gut microbiome, plasma levels of SCFAs, and biochemical indicators of renal function observed in the rats with CKD induced by dietary adenine were mitigated by GA. These findings are indicative of a link between uremia and the composition of the microbiome in connection with this disease. Dietary administration of GA to patients with CKD may improve their renal function via modulating the composition of their microbiome-a finding that certainly warrants further investigation.

Intestinal alkaline phosphatase modulation by food components: predictive, preventive, and personalized strategies for novel treatment options in chronic kidney disease

Alkaline phosphatase (AP) is a ubiquitous membrane-bound glycoprotein that catalyzes phosphate monoesters' hydrolysis from organic compounds, an essential process in cell signaling. Four AP isozymes have been described in humans, placental AP, germ cell AP, tissue nonspecific AP, and intestinal AP (IAP). IAP plays a crucial role in gut microbial homeostasis, nutrient uptake, and local and systemic inflammation, and its dysfunction is associated with persistent inflammatory disorders. AP is a strong predictor of mortality in the general population and patients with cardiovascular and chronic kidney disease (CKD). However, little is known about IAP modulation and its possible consequences in CKD, a disease characterized by gut microbiota imbalance and persistent low-grade inflammation. Mitigating inflammation and dysbiosis can prevent cardiovascular complications in patients with CKD, and monitoring factors such as IAP can be useful for predicting those complications. Here, we review IAP's role and the results of nutritional interventions targeting IAP in experimental models to prevent alterations in the gut microbiota, which could be a possible target of predictive, preventive, personalized medicine (PPPM) to avoid CKD complications. Microbiota and some nutrients may activate IAP, which seems to have a beneficial impact on health; however, data on CKD remains scarce.

Phlorizin ameliorates obesity-associated endotoxemia and insulin resistance in high-fat diet-fed mice by targeting the gut microbiota and intestinal barrier integrity

Phlorizin (PHZ) is one of phytonutrients in apples that contributes to the health-promoting effect implicated by the saying, 'an apple a day keeps the doctor away'. PHZ was firstly identified as a competitive inhibitor of sodium-glucose co-transporters-2 (SGLT2); however, its low bioavailability makes it hard to fully explain its pharmacological mechanisms. This study aimed to investigate the ameliorating effect of PHZ on high-fat diet (HFD)-induced obesity via modulating the "gut microbiota-barrier axis". Firstly, C57BL/6 J mice were fed a normal chow diet (NCD) or HFD coadministered with or without PHZ for 12 weeks. Our results showed that PHZ supplementation significantly reduced HFD-induced body weight gain (P < .001), alleviated metabolic disorders (MDs) like insulin resistance (P < .001) and elevation of serum lipopolysaccharides (LPS) (P < .001), attenuated HFD-induced gut microbiota alterations, enhanced short-chain fatty acids (SCFAs) production (P < .001), and inhibited fecal LPS production (P < .001). To investigate the role of the fecal microbiota in the observed beneficial effects, a fecal microbiota transplantation (FMT) experiment was performed by transplanting the feces of the four groups of mice (as donor mice) daily collected from the fourth week to a new batch of acclimatized HFD-fed mice. Our results confirmed that feeding the gut contents of the PHZ-modulated mice could attenuate HFD-induced MDs, accompanied by enhanced glucagon-like peptide 2 (GLP-2) secretion (P < .001) and restoration of HFD-induced damage in the gut epithelial barrier. This study has provided evidence that the "gut microbiota-barrier axis" was an alternative target for the anti-obesity effect of PHZ. This work has also provided an explanation for the high efficacy of PHZ despite the low bioavailability, and PHZ holds great potential to be developed as a functional food ingredient.

Dose-Dependent Effects of Dietary Xylooligosaccharides Supplementation on Microbiota, Fermentation and Metabolism in Healthy Adult Cats

In order to investigate the effect and appropriate dose of prebiotics, this study evaluated the effect of two levels of xylooligosaccharides (XOS) in cats. Twenty-four healthy adult cats were divided into three groups: no-XOS control diet with 1% cellulose; low XOS supplementation (LXOS) with 0.04% XOS and 0.96% cellulose; and high XOS supplementation (HXOS) with 0.40% XOS and 0.60% cellulose. Both XOS groups increased blood 3-hydroxybutyryl carnitine levels and decreased hexadecanedioyl carnitine levels. Both XOS treatments displayed an increased bacterial abundance of Blautia, Clostridium XI, and Collinsella and a decreased abundance of Megasphaera and Bifidobacterium. LXOS groups increased fecal pH and bacterial abundance of Streptococcus and Lactobacillus, decreased blood glutaryl carnitine concentration, and Catenibacterium abundance. HXOS group showed a more distinct microbiome profile and higher species richness, and an increased bacterial abundance of Subdoligranulum, Ruminococcaceae genus (unassigned genus), Erysipelotrichaceae genus, and Lachnospiraceae. Correlations between bacterial abundances and blood and fecal parameters were also observed. In conclusion, XOS could benefit feline gut health by altering microbiota; its effects dependant on the dose. The higher-dose XOS increased bacterial populations that possibly promoted intestinal fermentation, while the lower dose altered populations of carbohydrate-metabolic microbiota and possibly modulated host metabolism. Low-dose prebiotics may become a trend in future studies.

Gluten free sourdough bread enriched with cricket flour for protein fortification: Antioxidant improvement and Volatilome characterization

Insects represent a novel source of edible high nutritional value proteins which are gaining increasing interest as an alternative to traditional animal foods. In this work, cricket flour was used to produce gluten-free sourdough breads, suitable for celiac people and "source of proteins". The doughs were fermented by different methods and pH and microbial growth, volatile compounds, protein profile, and antioxidant activity, before and after baking, were analyzed and compared to standard gluten-free doughs. The results showed that cricket-enriched doughs and the standard had similar fermentation processes. Cricket enrichment conferred to the breads a typical flavoring profile, characterized by a unique bouquet of volatile compounds, made by nonanoic acid, 2,4-nonadienal (E,E), 1-hexanol, 1-heptanol, and 3-octen-2-one, expressed in different amounts depending on the type of inoculum. Finally, antioxidant activities were significantly enhanced in cricket breads, indicating that cricket powder provides to bakery gluten-free goods high nutritional value proteins and antioxidant properties.

Plant-based diets to manage the risks and complications of chronic kidney disease

Traditional dietary recommendations for patients with chronic kidney disease (CKD) focus on the quantity of nutrients consumed. Without appropriate dietary counselling, these restrictions can result in a low intake of fruits and vegetables and a lack of diversity in the diet. Plant nutrients and plant-based diets could have beneficial effects in patients with CKD: increased fibre intake shifts the gut microbiota towards reduced production of uraemic toxins; plant fats, particularly olive oil, have anti-atherogenic effects; plant anions might mitigate metabolic acidosis and slow CKD progression; and as plant phosphorus has a lower bioavailability than animal phosphorus, plant-based diets might enable better control of hyperphosphataemia. Current evidence suggests that promoting the adoption of plant-based diets has few risks but potential benefits for the primary prevention of CKD, as well as for delaying progression in patients with CKD G3-5. These diets might also help to manage and prevent some of the symptoms and metabolic complications of CKD. We suggest that restriction of plant foods as a strategy to prevent hyperkalaemia or undernutrition should be individualized to avoid depriving patients with CKD of these potential beneficial effects of plant-based diets. However, research is needed to address knowledge gaps, particularly regarding the relevance and extent of diet-induced hyperkalaemia in patients undergoing dialysis.

Prebiotic Therapy with Inulin Associated with Low Protein Diet in Chronic Kidney Disease Patients: Evaluation of Nutritional, Cardiovascular and Psychocognitive Parameters

A relationship between dysbiotic gut microbiome and chronic kidney disease (CKD) has been recently documented; it contributes to CKD-related complications, including cardiovascular disease. Aim: We tested how a low-protein diet (LPD)-with or without oral inulin supplementation as a prebiotic-modulates some inflammatory, atherosclerosis and endothelial dysfunction indices and nutritional markers, as well as psychocognitive functions in CKD patients. We conducted a prospective, case-control study on CKD patients on conservative therapy, divided in two groups: the intervention group treated with LPD (0.6 g/kg/day) plus inulin (19 g/day) and a control group treated with LPD without inulin, for six consecutive months. Clinical and hematochemical parameters as well as instrumental, and psychocognitive assessments (by SF-36 survey and MMSE, HAM-D, BDI-II) were recorded in all the participants at baseline (T0), at three months (T1) and at six months (T2). A total of 41 patients were enrolled: 18 in the intervention group and 23 in the control group. At T2, in both groups, we observed a significant reduction of serum nitrogen and phosphorus (p ≤ 0.01) and serum uric acid (p ≤ 0.03), and an improvement in metabolic acidosis (bicarbonates, p ≤ 0.01; base excess, p ≤ 0.02). Moreover, at T2 the intervention group showed a reduction in serum insulin (p = 0.008) and fasting glucose levels (p = 0.022), HOMA-IR (p = 0.004), as well as lower total serum cholesterol (p = 0.012), triglycerides (p = 0.016), C-reactive protein (p = 0.044) and homocysteine (p = 0.044) and higher HDL (p < 0.001) with respect to baseline. We also observed a significant amelioration of some quality of life and functional status indices (SF-36 survey) among the intervention group compared to controls, without a significant improvement in the cognitive state (MMSE). On the other hand, an amelioration in mood (by HAM-D and BDI-II) was found in the intervention group and in controls (only by BID-II). In conclusion, LPD in association with oral inulin supplementation improved glycemic and lipid metabolism and ameliorated the systemic inflammatory state, likely reducing cardiovascular risk in CKD patients and this may represent a promising therapeutic option, also improving quality of life and mood.

Resistant starch supplementation effects on plasma indole 3-acetic acid and aryl hydrocarbon receptor mRNA expression in hemodialysis patients: Randomized, double blind and controlled clinical trial

Introduction:

Gut microbiota imbalance is linked to high uremic toxins production such as indole-3-acetic acid (IAA) in chronic kidney disease patients. This toxin can activate the aryl hydrocarbon receptor (AhR), a ligand-activated transcription factor involved with inflammation. Strategies to restore gut microbiota balance can be associated with reduced production of IAA and its deleterious effects. This study aimed to evaluate prebiotic resistant starch (RS) supplementation effects on IAA plasma levels and AhR mRNA expression in CKD patients on hemodialysis (HD).

Methods:

This randomized, double-blind and placebo-controlled clinical trial evaluated forty-two stable HD patients allocated in RS (n=22) or placebo (n=20) groups. Patients received, alternately, cookies and sachets containing 16 g/day of RS (Hi-Maize 260^®) or manioc flour for four weeks. Fasting pre-dialysis blood samples were collected and IAA plasma levels measured by high performance liquid chromatography. Peripheral blood mononuclear cells were isolated and processed for AhR and nuclear factor kappa B (NF-κB) mRNA expression analyzes by quantitative real-time PCR. Anthropometric and biochemical parameters, as well as food intake were also evaluated.

Results:

Thirty-one patients completed the study, 15 in the RS group and 16 in the placebo group. Although there was no significant alteration in IAA plasma levels, neither in AhR mRNA expression and NF-κB mRNA expression after RS supplementation, a positive correlation (r=0.48; p=0.03) was observed between IAA plasma levels and AhR expression at baseline.

Conclusion:

Even though prebiotic RS supplementation did not influence IAA levels or AhR expression, their positive association reinforces a possible interaction between them.

Microbiota-independent immunological effects of non-digestible oligosaccharides in the context of inflammatory bowel diseases

The aim of the present paper is to review the effects of non-digestible oligosaccharides (NDO) on immunity, focusing on their microbiota-independent mechanisms of action, as well as to explore their potential beneficial role in inflammatory bowel diseases (IBD). IBD are chronic, inflammatory conditions of the gastrointestinal tract. Individuals with IBD have an aberrant immune response to commensal microbiota, resulting in extensive mucosal inflammation and increased intestinal permeability. NDO are prebiotic fibres well known for their role in supporting intestinal health through modulation of the gut microbiota. NDO reach the colon intact and are fermented by commensal bacteria, resulting in the production of SCFA with immunomodulatory properties. In disease states characterised by increased gut permeability, prebiotics may also bypass the gut barrier and directly interact with intestinal and systemic immune cells, as demonstrated in patients with IBD and in infants with an immature gut. In vitro models show that fructooligosaccharides, inulin and galactooligosaccharides exert microbiota-independent effects on immunity by binding to toll-like receptors on monocytes, macrophages and intestinal epithelial cells and by modulating cytokine production and immune cell maturation. Moreover, animal models and human supplementation studies demonstrate that some prebiotics, including inulin and lactulose, might reduce intestinal inflammation and IBD symptoms. Although there are convincing preliminary data to support NDO as immunomodulators in the management of IBD, their mechanisms of action are still unclear and larger standardised studies need to be performed using a wider range of prebiotics.

The Controversial Role of Human Gut Lachnospiraceae

The complex polymicrobial composition of human gut microbiota plays a key role in health and disease. Lachnospiraceae belong to the core of gut microbiota, colonizing the intestinal lumen from birth and increasing, in terms of species richness and their relative abundances during the host's life. Although, members of Lachnospiraceae are among the main producers of short-chain fatty acids, different taxa of Lachnospiraceae are also associated with different intra- and extraintestinal diseases. Their impact on the host physiology is often inconsistent across different studies. Here, we discuss changes in Lachnospiraceae abundances according to health and disease. With the aim of harnessing Lachnospiraceae to promote human health, we also analyze how nutrients from the host diet can influence their growth and how their metabolites can, in turn, influence host physiology.

Prebiotic potential of hemp blended drinks fermented by probiotics

Plant-based drinks as substitute for milk consumption are raising striking interest in the food industry. Soy and rice drinks are the most studied and successful milk substitutes. An untapped source is hemp seed, which is a powerhouse of nutrients bearing bioactive compounds, but the production of derived drink is limited. The present work is about introducing new formulations of commercial hemp seed-derived drink to be fermented with probiotics (Lactobacillus fermentum, Lb. plantarum and Bifidobacterium bifidum). In this work for the first time the prebiotic activity of different hemp seed drinks was assessed by cultural and quantitative PCR methods. In addition, to better describe the prebiotic potential, VOCs alkenes and volatile organic acids were characterized by a metabolomic approach via GC-MS SPME. Obtained results showed that the hemp seed drinks had strong prebiotic activity, ability to support probiotics growth and to increase the content of some bioactive compounds. These outputs are in part due to the presence of different terpenes that inhibit the growth of enteropathogens and to high levels of acetate, propionate and butyrate produced during fermentation that support the growth of probiotics. Although the health potential of hemp seed is well known, derived drinks are hitherto scarcely transformed and distributed, thus this work could provide some basics to produce prebiotic and probiotic fermented hemp seed drinks.

Exploring the Benefit of 2-Methylbutyric Acid in Patients Undergoing Hemodialysis Using a Cardiovascular Proteomics Approach

Short-chain fatty acids (SCFAs) can reduce pro-inflammatory parameters and oxidative stress, providing potential cardiovascular (CV) benefits. Although some evidence links SCFAs with host metabolic health via several biological mechanisms, the role of SCFA on CV disease in patients with kidney disease remains unclear. Herein, we investigate the association between a SCFA, 2-methylbutyric acid, and target CV proteomics to explore the potential pathophysiology of SCFA-related CV benefit in patients with kidney disease. Circulating 2-methylbutyric acid was quantified by high-performance liquid chromatography and 181 CV proteins by a proximity extension assay in 163 patients undergoing hemodialysis (HD). The associations between 2-methylbutyric acid and CV proteins were evaluated using linear regression analysis with age and gender, and multiple testing adjustment. The selected CV protein in the discovery phase was further confirmed in multivariable-adjusted models and evaluated by continuous scale association. The mean value of circulating 2-methylbutyric acid was 0.22 ± 0.02 µM, which was negatively associated with bone morphogenetic protein 6 (BMP-6) according to the false discovery rate (FDR) multiple testing adjustment method. The 2-methylbutyric acid level remained negatively associated with BMP-6 (β coefficient -1.00, 95% confidence interval -1.45 to -0.55, p < 0.001) after controlling for other CV risk factors in multivariable models. The cubic spline curve demonstrated a linear relationship. In conclusion, circulating 2-methylbutyric acid level was negatively associated with BMP-6, suggesting that this pathway maybe involved in vascular health in patients undergoing HD. However, further in vitro work is still needed to validate the translation of the mechanistic pathways.

Effect of Low-Protein Diet and Inulin on Microbiota and Clinical Parameters in Patients with Chronic Kidney Disease

Introduction: The gut microbiota has coevolved with humans for a mutually beneficial coexistence and plays an important role in health and disease. A dysbiotic gut microbiome may contribute to progression to chronic kidney disease (CKD) and CKD-related complications such as cardiovascular disease. Microbiota modulation through the administration of prebiotics may represent an important therapeutic target. Aim: We sought to evaluate the effects of a low-protein diet (LPD) (0.6 g/kg/day) with or without the intake of the prebiotic inulin (19 g/day) on microbiota and clinical parameters in CKD patients. Materials and Methods: We performed a longitudinal, prospective, controlled, and interventional study on 16 patients: 9 patients treated with LPD (0.6 g/kg/day) and inulin (19 g/day) and 7 patients (control group) treated only with LPD (0.6 g/kg/day). Clinical evaluations were performed and fecal samples were collected for a subsequent evaluation of the intestinal microbiota in all patients. These tests were carried out before the initiation of LPD, with or without inulin, at baseline (T0) and at 6 months (T2). The microbiota of 16 healthy control (HC) subjects was also analyzed in order to identify potential dysbiosis between patients and healthy subjects. Results: Gut microbiota of CKD patients was different from that of healthy controls. The LPD was able to significantly increase the frequencies of Akkermansiaceae and Bacteroidaceae and decrease the frequencies of Christensenellaceae, Clostridiaceae, Lactobacillaceae, and Pasteurellaceae. Only Bifidobacteriaceae were increased when the LPD was accompanied by oral inulin intake. We showed a significant reduction of serum uric acid (SUA) and C-reactive protein (CRP) in patients treated with LPD and inulin (p = 0.018 and p = 0.003, respectively), an improvement in SF-36 (physical role functioning and general health perceptions; p = 0.03 and p = 0.01, respectively), and a significant increase of serum bicarbonate both in patients treated with LPD (p = 0.026) or with LPD and inulin (p = 0.01). Moreover, in patients treated with LPD and inulin, we observed a significant reduction in circulating tumor necrosis factor alpha (TNF-α) (p = 0.041) and plasma nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX2) (p = 0.027) levels. We did not find a significant difference in the circulating levels of Interleukin (IL)-1β (p = 0.529) and IL-6 (p = 0.828) in the two groups. Conclusions: LPD, associated or not with inulin, modified gut microbiota and modulated inflammatory and metabolic parameters in patients with CKD. Our results suggest that interventions attempting to modulate the gut microbiome may represent novel strategies to improve clinical outcomes in CKD patients and may provide useful therapeutic effects.

The Skin and Gut Microbiome and Its Role in Common Dermatologic Conditions

Microorganisms inhabit various areas of the body, including the gut and skin, and are important in maintaining homeostasis. Changes to the normal microflora due to genetic or environmental factors can contribute to the development of various disease states. In this review, we will discuss the relationship between the gut and skin microbiome and various dermatological diseases including acne, psoriasis, rosacea, and atopic dermatitis. In addition, we will discuss the impact of treatment on the microbiome and the role of probiotics.

Vegetable-Based Diets for Chronic Kidney Disease? It Is Time to Reconsider

Traditional dietary recommendations to renal patients limited the intake of fruits and vegetables because of their high potassium content. However, this paradigm is rapidly changing due to the multiple benefits derived from a fundamentally vegetarian diet such as, improvement in gut dysbiosis, reducing the number of pathobionts and protein-fermenting species leading to a decreased production of the most harmful uremic toxins, while the high fiber content of these diets enhances intestinal motility and short-chain fatty acid production. Metabolic acidosis in chronic kidney disease (CKD) is aggravated by the high consumption of meat and refined cereals, increasing the dietary acid load, while the intake of fruit and vegetables is able to neutralize the acidosis and its deleterious consequences. Phosphorus absorption and bioavailability is also lower in a vegetarian diet, reducing hyperphosphatemia, a known cause of cardiovascular mortality in CKD. The richness of multiple plants in magnesium and vitamin K avoids their deficiency, which is common in these patients. These beneficial effects, together with the reduction of inflammation and oxidative stress observed with these diets, may explain the reduction in renal patients' complications and mortality, and may slow CKD progression. Finally, although hyperkalemia is the main concern of these diets, the use of adequate cooking techniques can minimize the amount absorbed.

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.

Endocrine organs of cardiovascular diseases: Gut microbiota

Gut microbiota (GM) is a collection of bacteria, fungi, archaea, viruses and protozoa, etc. They inhabit human intestines and play an essential role in human health and disease. Close information exchange between the intestinal microbes and the host performs a vital role in digestion, immune defence, nervous system regulation, especially metabolism, maintaining a delicate balance between itself and the human host. Studies have shown that the composition of GM and its metabolites are firmly related to the occurrence of various diseases. More and more researchers have demonstrated that the intestinal microbiota is a virtual 'organ' with endocrine function and the bioactive metabolites produced by it can affect the physiological role of the host. With deepening researches in recent years, clinical data indicated that the GM has a significant effect on the occurrence and development of cardiovascular diseases (CVD). This article systematically elaborated the relationship between metabolites of GM and its effects, the relationship between intestinal dysbacteriosis and cardiovascular risk factors, coronary heart disease, myocardial infarction, heart failure and hypertension and the possible pathogenic mechanisms. Regulating the GM is supposed to be a potential new therapeutic target for CVD.

Kefir Supplementation Modifies Gut Microbiota Composition, Reduces Physical Fatigue, and Improves Exercise Performance in Mice

The present study evaluated the potential beneficial effect of kefir (KF) against fatigue. Furthermore, the composition of the gut microbiota is related to health benefits in the host; therefore, the study also investigated the effect of KF on the gut microbiota composition. Male ICR mice from four groups (n = 8 per group) were orally administered KF once daily for four weeks at 0, 2.15, 4.31, and 10.76 g/kg/day and were designated as the vehicle, KF-1X, KF-2X, and KF-5X groups, respectively. The gut microbiota was analyzed using 16S rRNA gene sequencing. The results showed a significant clustering of cecum after treatment in the vehicle, KF-1X, KF-2X, and KF-5X groups. The KF-2X and KF-5X groups showed a decreased Firmicutes/Bacteroidetes ratio compared with the vehicle group. In addition, anti-fatigue activity and exercise performance were evaluated on the basis of exhaustive swimming time, forelimb grip strength, and levels of serum lactate, ammonia, glucose, blood urea nitrogen (BUN), and creatine kinase (CK) after a swimming exercise. The exhaustive swimming time for the KF-1X, KF-2X, and KF-5X groups was significantly longer than that for the vehicle group, and the forelimb grip strength of the KF-1X, KF-2X, and KF-5X groups was also significantly higher than that of the vehicle group. KF supplementation also decreased serum lactate, ammonia, BUN, and CK levels after the swimming test. However, tissue glycogen content, an important energy source for exercise, increased significantly with KF supplementation. Thus, KF supplementation can alter the gut microbiota composition, improve performance, and combat physical fatigue.

Nutrients, Nutraceuticals, and Xenobiotics Affecting Renal Health

Chronic kidney disease (CKD) affects 8–16% of the population worldwide. In developed countries, the most important risk factors for CKD are diabetes, hypertension, and obesity, calling into question the importance of educating and acting on lifestyles and nutrition. A balanced diet and supplementation can indeed support the maintenance of a general health status, including preservation of renal function, and can help to manage and curb the main risk factors for renal damage. While the concept of protein and salt restriction in nephrology is historically acknowledged, the role of some nutrients in renal health and the importance of nutrition as a preventative measure for renal care are less known. In this narrative review, we provide an overview of the demonstrated and potential actions of some selected nutrients, nutraceuticals, and xenobiotics on renal health and function. The direct and indirect effects of fiber, protein, fatty acids, curcumin, steviol glycosides, green tea, coffee, nitrates, nitrites, and alcohol on kidney health are reviewed here. In view of functional and personalized nutrition, understanding the renal and systemic effects of dietary components is essential since many chronic conditions, including CKD, are related to systemic dysfunctions such as chronic low-grade inflammation.

Gut microbiota, hypertension and chronic kidney disease: Recent advances

A large number of different microbial species populates intestine. Extensive research has studied the entire microbial population and their genes (microbiome) by using metagenomics, metatranscriptomics and metabolomic analysis. Studies suggest that the imbalances of the microbial community causes alterations in the intestinal homeostasis, leading to repercussions on other systems: metabolic, nervous, cardiovascular, immune. These studies have also shown that alterations in the structure and function of the gut microbiota play a key role in the pathogenesis and complications of Hypertension (HTN) and Chronic Kidney Disease (CKD). Increased blood pressure (BP) and CKD are two leading risk factors for cardiovascular disease and their treatment represents a challenge for the clinicians. In this Review, we discuss mechanisms whereby gut microbiota (GM) and its metabolites act on downstream cellular targets to contribute to the pathogenesis of HTN and CKD, and potential therapeutic implications.