Obesity and the gut microbiota: does up-regulating colonic fermentation protect against obesity and metabolic disease?

Gastrointestinal Permeability After Bariatric Surgery: A Systematic Review

Gastrointestinal permeability refers to the movement of substances across the gut wall. This is mediated by endotoxemia (bacterial products entering the systemic circulation), and is associated with metabolic disease. The effect of bariatric surgery on permeability remains uncertain; the associated dietary, metabolic and weight changes are suggested to influence, or trigger, altered permeability. The primary aim of this study is to synthesize evidence and analyze the effect of bariatric surgery on permeability. A systematic review was performed, searching MEDLINE, EMBASE, and Scopus until February 2023, using MESH terms "intestinal permeability", "bariatric", for studies reporting in vivo assessment of permeability. Three cohort studies and two case series were identified (n=96). Data was heterogeneous; methodology and controls preclude meta-analysis. Gastroduodenal permeability reduced post-sleeve gastrectomy (SG). Two studies showed an increase in small intestinal permeability after biliopancreatic diversion. Two studies revealed a decrease in post-Roux-en-Y gastric bypass. One study identified increased colonic permeability six months post-SG. Evidence regarding permeability change after bariatric surgery is conflicting, notably for the small intestine. Impaired colonic permeability post-SG raises concerns regarding colonic protein fermentation and harmful dietary sequelae. There are multiple interacting variables confounding gastrointestinal permeability change; procedure type, altered microbiota and metabolic response to surgery. Further understanding of this important aspect of obesity is required, both before and after bariatric surgery.

The causal impact of gut microbiota on circulating adipokine concentrations: a two-sample Mendelian randomization study

PURPOSE

Evidence from previous experimental and observational research demonstrates that the gut microbiota is related to circulating adipokine concentrations. Nevertheless, the debate as to whether gut microbiome composition causally influences circulating adipokine concentrations remains unresolved. This study aimed to take an essential step in elucidating this issue.

METHODS

We used two-sample Mendelian randomization (MR) to causally analyze genetic variation statistics for gut microbiota and four adipokines (including adiponectin, leptin, soluble leptin receptor [sOB-R], and plasminogen activator inhibitor-1 [PAI-1]) from large-scale genome-wide association studies (GWAS) datasets. A range of sensitivity analyses was also conducted to assess the stability and reliability of the results.

RESULTS

The composite results of the MR and sensitivity analyses revealed 22 significant causal associations. In particular, there is a suggestive causality between the family Clostridiaceae1 (IVW: β = 0.063, P = 0.034), the genus Butyrivibrio (IVW: β = 0.029, P = 0.031), and the family Alcaligenaceae (IVW: β=-0.070, P = 0.014) and adiponectin. Stronger causal effects with leptin were found for the genus Enterorhabdus (IVW: β=-0.073, P = 0.038) and the genus Lachnospiraceae (NK4A136 group) (IVW: β=-0.076, P = 0.01). Eight candidate bacterial groups were found to be associated with sOB-R, with the phylum Firmicutes (IVW: β = 0.235, P = 0.03) and the order Clostridiales (IVW: β = 0.267, P = 0.028) being of more interest. In addition, the genus Roseburia (IVW: β = 0.953, P = 0.022) and the order Lactobacillales (IVW: β=-0.806, P = 0.042) were suggestive of an association with PAI-1.

CONCLUSION

This study reveals a causal relationship between the gut microbiota and circulating adipokines and may help to offer novel insights into the prevention of abnormal concentrations of circulating adipokines and obesity-related diseases.

Tuning Expectations to Reality: Don't Expect Increased Gut Microbiota Diversity with Dietary Fiber

Dietary approaches, particularly those including fiber supplementation, can be used to promote health benefits by shaping gut microbial communities. Whereas community diversity measures, such as richness and evenness, are often used in microbial ecology to make sense of these complex and vast microbial ecosystems, it is less clear how these concepts apply when dietary fiber supplementation is given. In this perspective, we summarize and demonstrate how factors including experimental approach, number of bacteria sharing a dietary fiber, and initial relative abundances of bacteria that use a fiber can significantly affect diversity outcomes in fiber fermentation studies. We also show that a reduction in alpha diversity is possible, and perhaps expected, for most approaches that use fermentable fibers to beneficially shape the gut microbial community while still achieving health-related improvements.

Dysregulation of Ruminococcaceae and Megamonas could be predictive markers for rapid progression of mild cognitive impairment

BACKGROUND

Intestinal flora dysregulation may affect the development of Alzheimer's disease (AD). However, the correlation between intestinal flora and rapid progression of mild cognitive impairment (MCI) is rarely reported. Our aim was to investigate the features of the intestinal flora in patients with rapidly progressive MCI.

METHOD

A total of 1013 participants were screened, in which 87 patients with MCI were followed up for two years. At the baseline time point, fecal samples of the patients were sequenced via the microbial diversity high-throughput 16 s-rDNA.

RESULTS

After a two-year follow-up, 30 patients with MCI presented rapidly progressive cognitive impairment, whereas the 57 patients remained unprogressive. Analyses of their fecal samples showed that the abundance of 11 intestinal microflora were significantly different between the two groups at the baseline time point. Further analyses revealed that the decrease of Ruminococcaceae abundance and the increase of Megamonas abundance were significantly correlated with the progression of MCI. Also, the decreased Ruminococcaceae was independently associated with several factors such as P-tau181, and the increased Megamonas was independently associated with diabetes, low-density lipoprotein, median cell count.

CONCLUSION

The decrease of Ruminococcaceae and the increase of Megamonas could act as predictive markers for the rapidly progressive MCI.

Partially defatted rather than native poppy seeds beneficially alter lipid metabolism in rats fed a high-fat diet

Partially defatted poppy seeds, a by-product of poppy oil cold pressing, could be an interesting dietary supplement for obesity management. The aim of this study was to compare the effects of dietary supplementation with a small amount of native or partially defatted poppy seeds on gastrointestinal function and lipid metabolism in rats fed a high-fat diet. The defatted poppy seeds had, among others, lower fat content and higher fibre and protein content than native poppy seeds. The rats fed with a high-fat diet were characterised by severe metabolic disorders, especially in the liver, and poppy seeds were unable to prevent them. However, depending on the seed form, dietary supplementation with poppy seeds differentially affected the microbial and endogenous lipid metabolism in rats. In the distal intestine, both dietary seed forms stimulated microbial acetate production, and the supplementation with partially defatted poppy seeds additionally inhibited isobutyrate and isovalerate formation, which indicates a reduction in putrefaction. Both dietary seed forms increased cholesterol accumulation in the liver. Only dietary supplementation with partially defatted poppy seeds attenuated visceral fat and hepatic triglyceride accumulations and lowered blood triglyceride concentrations, and at the transcriptional level, the inhibition of SREBP-1c, which upregulates genes responsible for de novo lipogenesis, was additionally observed in this organ. In conclusion, a low and regular consumption of partially defatted poppy seeds may be beneficial in managing obesity-related disorders.

Effects of probiotic administration on overweight or obese children: a meta-analysis and systematic review

BACKGROUND

This paper aimed to examine the effects of probiotics on eight factors in overweight or obese children by meta-analysis, namely, body mass index (BMI), total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), adiponectin, leptin and tumor necrosis factor-α (TNF-α) and summarize the mechanisms of action of probiotics based on the existing researches.

METHODS

Six databases (PubMed, Web of Science, Embase, Cochrane Library, SinoMed and CNKI) were searched until March 2023. Review Manager 5.4 was used for meta-analysis. The data were analysed using weighted mean differences (WMDs) or standardized mean differences (SMDs) under a fixed effect model or random effect model to observe the effects of probiotic administration on the included indicators.

RESULTS

Four publications with a total of 206 overweight or obesity children were included. According to the meta-analysis, probiotics were able to significantly decrease the levels of HDL-C (MD, 0.06; 95% CI 0.03, 0.09; P = 0.0001), LDL-C (MD, - 0.06; 95% CI - 0.12, - 0.00; P = 0.04), adiponectin (MD, 1.39; 95% CI 1.19, 1.59; P < 0.00001), leptin (MD, - 2.72; 95% CI - 2.9, - 2.54; P < 0.00001) and TNF-α (MD, - 4.91; 95% CI - 7.15, - 2.67; P < 0.0001) compared to those in the placebo group. Still, for BMI, the palcebo group seemed to be better than the probiotic group (MD, 0.85; 95% CI 0.04, 1.66; P = 0.04). TC (MD, - 0.05; 95% CI - 0.12, 0.02; P = 0.14) and TG (MD, - 0.16; 95% CI - 0.36, 0.05; P = 0.14) were not different between two groups.

CONCLUSIONS

This review drew that probiotics might act as a role in regulating HDL-C, LDL-C, adiponectin, leptin and TNF-α in overweight or obesity children. Additionally, our systematic review yielded that probiotics might regulate lipid metabolism and improve obese associated symptoms by some paths. This meta-analysis has been registered at PROSPERO with ID: CRD42023408359.

Gut microbiota and cognitive development in infant mice: Quantity and source of potable water

Not only the water quantity consumed but also the source of drinking water has been considered for their health benefits, but there is limited evidence. We aimed to determine whether the amount and type of drinking water affect physiological and biological functions, including brain function, by confirming how it affects gut microbiota which has an important regulatory role in host physiology. Three-week-old infant mice were subjected to 1) a water restriction experiment (control group, ad libitum consumption of distilled water; dehydration group, time-limited access to distilled water [15 min/day]) and 2) different water source experiment (distilled water, purified water, spring water, and tap water groups). The gut microbiota and cognitive development were analyzed using the 16S ribosomal ribonucleic acid sequencing method and the Barnes maze, respectively. The relative abundance of Firmicutes and Bacteroidetes and the Firmicutes-to-Bacteroidetes ratio (F/B ratio) changed depending on age (juveniles vs. infants). Insufficient water intake reversed these developmental changes, showing that the relative abundances of Bacteroidetes and Firmicutes and the F/B ratio in dehydrated juvenile mice were similar to those in normal infant mice. Additionally, clustering analysis revealed no significant differences in the intestinal flora in the mice from the different drinking water sources; however, dehydration significantly altered the composition of the genera compared to the other water source groups wherein water was provided ad libitum. Moreover, cognitive development was significantly disrupted by insufficient water intake, although the type of drinking water had no significant influence. Cognitive decline, measured by relative latency, was positively associated with the relative abundance of unclassified Erysipelotrichaceae that were in significantly high relative abundance in the dehydration group. These results suggest that the water quantity consumed, rather than the mineral content of drinking water, is imperative for shaping the early gut microbiota associated with cognitive development during infancy.

Anti-Obesity Effects of SPY Fermented with Lactobacillus rhamnosus BST-L.601 via Suppression of Adipogenesis and Lipogenesis in High-Fat Diet-Induced Obese Mice

In this research, the potential anti-obesity efficacy of Lactobacillus rhamnosus BST-L.601 and its fermented product (named SPY) with mashed sweet potato paste were investigated using 3T3-L1 preadipocytes and high-fat diet (HD)-induced obese mice. SPY (0-0.5 mg/mL) dose-dependently and significantly reduced lipid accumulation and TG content and the expression of adipogenic markers (C/EBPα, PPAR-γ, and aP2) and fatty acid synthetic pathway proteins (ACC and FAS) in 3T3-L1 adipocytes, demonstrating that SPY suppresses adipocyte differentiation and lipogenesis. Oral administration of SPY (4 × 10⁷ CFU/kg body weight) to HD-induced obese mice for 12 weeks significantly reduced the body and liver weight, the size of adipocytes, and the weight of epididymal, visceral, and subcutaneous fat tissues. SPY was more effective in decreasing body weight gain in HD mice than in treatment with BST-L.601 alone. Administration of SPY or BST-L.601 also reduced the serum level of total cholesterol and LDL cholesterol and leptin secretion at a similar level. These results revealed that both SPY and BST-L.601 effectively suppress HD-induced adipogenesis and lipogenesis, suggesting that these materials would be useful in the functional foods industry to ameliorate and/or prevent obesity.

Characterization of gut microbiota in adults with coronary atherosclerosis

Background

Cardiovascular disease, which is mainly caused by coronary atherosclerosis, is one of the leading causes of death and disability worldwide. Gut microbiota likely play an important role in coronary atherosclerosis. This study aims to investigate the microbiota profile of adults with coronary atherosclerosis to provide a theoretical basis for future research.

Methods

Fecal samples were collected from 35 adult patients diagnosed with coronary atherosclerosis and 32 healthy adults in Nanjing, China, and the V3-V4 region of 16S rDNA genes was sequenced using high-throughput sequencing. Differences in alpha diversity, beta diversity, and gut microbiota composition between the two groups were then compared.

Results

A beta diversity analysis revealed significant differences between adults with coronary atherosclerosis and controls, but there was no statistical difference in alpha diversity between the two groups. There were also differences in the composition of the gut microbiota between the two groups. The genera, Megamonas, Streptococcus, Veillonella, Ruminococcus_torques_group, Prevotella_2, Tyzzerella_4, were identified as potential biomarkers for coronary atherosclerosis.

Conclusion

There are some differences in the gut microbiota of adults with coronary atherosclerosis compared to healthy adults. The insights from this study could be used to explore microbiome-based mechanisms for coronary atherosclerosis.

Anthocyanins ameliorate obesity-associated metainflammation: Preclinical and clinical evidence

The growing rates of obesity worldwide call for intervention strategies to help control the pathophysiological consequences of weight gain. The use of natural foods and bioactive compounds has been suggested as such a strategy because of their recognized antioxidant and anti-inflammatory properties. For example, polyphenols, especially anthocyanins, are candidates for managing obesity and its related metabolic disorders. Obesity is well known for the presence of metainflammation, which has been labeled as an inflammatory activation that leads to a variety of metabolic disorders, usually related to increased oxidative stress. Considering this, anthocyanins may be promising natural compounds able to modulate several intracellular mechanisms, mitigating oxidative stress and metainflammation. A wide variety of foods and extracts rich in anthocyanins have become the focus of research in the field of obesity. Here, we bring together the current knowledge regarding the use of anthocyanins as an intervention tested in vitro, in vivo, and in clinical trials to modulate metainflammation. Most recent research applies a wide variety of extracts and natural sources of anthocyanins, in diverse experimental models, which represents a limitation of the research field. However, the literature is sufficiently consistent to establish that the in-depth molecular analysis of gut microbiota, insulin signaling, TLR4-triggered inflammation, and oxidative stress pathways reveals their modulation by anthocyanins. These targets are interconnected at the cellular level and interact with one another, leading to obesity-associated metainflammation. Thus, the positive findings with anthocyanins observed in preclinical models might directly relate to the positive outcomes in clinical studies. In summary and based on the entirety of the relevant literature, anthocyanins can mitigate obesity-related perturbations in gut microbiota, insulin resistance, oxidative stress and inflammation and therefore may contribute as a therapeutic tool in people living with obesity.

Effects of chlorogenic acid on growth, metabolism, antioxidation, immunity, and intestinal flora of crucian carp (Carassius auratus)

In recent years, with the harm caused by the abuse of antibiotics and the increasing demand for green and healthy food, people gradually began to look for antibiotic alternatives for aquaculture. As a Chinese herbal medicine, leaf extract chlorogenic acid (CGA) of Eucommia ulmoides Oliver can improve animal immunity and antioxidant capacity and can improve animal production performance. In this study, crucian carp (Carassius auratus) was fed with complete feed containing 200 mg/kg CGA for 60 days to evaluate the antioxidant, immuno-enhancement, and regulation of intestinal microbial activities of CGA. In comparison to the control, the growth performance indexes of CGA-added fish were significantly increased, including final body weight, weight gain rate, and specific growth rate (P < 0.01), while the feed conversion rate was significantly decreased (P < 0.01). Intestinal digestive enzyme activity significantly increased (P < 0.01); the contents of triglyceride in the liver (P < 0.01) and muscle (P > 0.05) decreased; and the expression of lipid metabolism-related genes in the liver was promoted. Additionally, the non-specific immune enzyme activities of intestinal and liver tissues were increased, but the expression level of the adenylate-activated protein kinase gene involved in energy metabolism was not affected. The antioxidant capacity of intestinal, muscle, and liver tissues was improved. Otherwise, CGA enhanced the relative abundance of intestinal microbes, Fusobacteria and Firmicutes and degraded the relative abundance of Proteobacteria. In general, our data showed that supplementation with CGA in dietary had a positive effect on Carassius auratus growth, immunity, and balance of the bacteria in the intestine. Our findings suggest that it is of great significance to develop and use CGA as a natural non-toxic compound in green and eco-friendly feed additives.

Gut Microbiota and Time-Restricted Feeding/Eating: A Targeted Biomarker and Approach in Precision Nutrition

Each individual has a unique gut microbiota; therefore, the genes in our microbiome outnumber the genes in our genome by about 150 to 1. Perturbation in host nutritional status influences gut microbiome composition and vice versa. The gut microbiome can help in producing vitamins, hormones, and other active metabolites that support the immune system; harvest energy from food; aid in digestion; protect against pathogens; improve gut transit and function; send signals to the brain and other organs; oscillate the circadian rhythm; and coordinate with the host metabolism through multiple cellular pathways. Gut microbiota can be influenced by host genetics, medications, diet, and lifestyle factors from preterm to aging. Aligning with precision nutrition, identifying a personalized microbiome mandates the provision of the right nutrients at the right time to the right patient. Thus, before prescribing a personalized treatment, it is crucial to monitor and count the gut flora as a focused biomarker. Many nutritional approaches that have been developed help in maintaining and restoring an optimal microbiome such as specific diet therapy, nutrition interventions, and customized eating patterns. One of these approaches is time-restricted feeding/eating (TRF/E), a type of intermittent fasting (IF) in which a subject abstains from food intake for a specific time window. Such a dietary modification might alter and restore the gut microbiome for proper alignment of cellular and molecular pathways throughout the lifespan. In this review, we have highlighted that the gut microbiota would be a targeted biomarker and TRF/E would be a targeted approach for restoring the gut-microbiome-associated molecular pathways such as hormonal signaling, the circadian system, metabolic regulators, neural responses, and immune-inflammatory pathways. Consequently, modulation of the gut microbiota through TRF/E could contribute to proper utilization and availability of the nutrients and in this way confer protection against diseases for harnessing personalized nutrition approaches to improve human health.

Effects of the probiotic Lactiplantibacillus plantarum IMC 510® on body composition, biochemical parameters, gut microbiota composition and function, and clinical symptoms of overweight/obese subjects

Background and aim

In recent decades, obesity prevalence has reached epidemic proportions and considering the pivotal role of gut microbiota (GM) in the regulation of energy balance, alternative non-pharmacological approaches involving probiotics' administration have been proposed. The aim of the present study was to evaluate the effect of Lactiplantibacillus plantarum IMC 510® supplementation on anthropometric and biochemical parameters, GM composition and functionality, and gastrointestinal and general symptoms of overweight/obese subjects.

Methods

Forty overweight/obese subjects were randomly assigned to daily consume the probiotic Lactiplantibacillus plantarum IMC 510® or placebo for 3 months. Before and after the administration period, anthropometric and biochemical parameters, self-administered questionnaires, and plasma and stool samples were obtained from each participant. The GM characterization was performed with 16S rRNA sequencing, while fecal short (SCFAs) and medium (MCFAs) chain fatty acids were analyzed with a gas chromatography-mass spectrometry protocol.

Results

Compared to placebo, probiotic supplementation determined a significant decrease in body weight, BMI, waist circumference, waist-to-height ratio, and blood glucose. Moreover, probiotic administration produced a significant decrease of the genera Hafnia-Obesumbacterium and Romboutsia and an increase of Succiniclasticum spp.; conversely, placebo administration resulted in the decrease of Actinomycetaceae and an increase of both Alloprevotella spp. and of the levels of pro-inflammatory hexanoic and heptanoic acids.

Conclusion

Thanks to its effect in increasing some beneficial gut bacteria and lowering effects on waist circumference, fasting glucose levels and gastrointestinal symptoms of obese subjects, Lactiplantibacillus plantarum IMC 510® supplementation could represent a future and encouraging strategy for the prevention or treatment of obesity.

Obesity and Its Multiple Clinical Implications between Inflammatory States and Gut Microbiotic Alterations

Obesity is a chronic multifactorial disease that has become a serious health problem and is currently widespread over the world. It is, in fact, strongly associated with many other conditions, including insulin resistance, type 2 diabetes, cardiovascular and neurodegenerative diseases, the onset of different types of malignant tumors and alterations in reproductive function. According to the literature, obesity is characterized by a state of low-grade chronic inflammation, with a substantial increase in immune cells, specifically macrophage infiltrates in the adipose tissue which, in turn, secrete a succession of pro-inflammatory mediators. Furthermore, recent studies on microbiota have postulated new possible mechanisms of interaction between obesity and unbalanced nutrition with inflammation. This intestinal "superorganism" complex seems to influence not only the metabolic balance of the host but also the immune response, favoring a state of systemic inflammation and insulin resistance. This review summarizes the major evidence on the interactions between the gut microbiota, energetic metabolism and host immune system, all leading to a convergence of the fields of immunology, nutrients physiology and microbiota in the context of obesity and its possible clinical complications. Finally, possible therapeutic approaches aiming to rebalance the intestinal microbial ecosystem are evaluated to improve the alteration of inflammatory and metabolic states in obesity and related diseases.

The relationship of Megamonas species with nonalcoholic fatty liver disease in children and adolescents revealed by metagenomics of gut microbiota

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in children and adolescents. The gut microbiota plays an important role in the pathophysiology of NAFLD through the gut-liver axis. Therefore, we aimed to investigate the genus and species of gut microbiota and their functions in children and adolescents with NAFLD. From May 2017 to July 2018, a total of 58 children and adolescents, including 27 abnormal weight (AW) (obese) NAFLD patients, 16 AW non-NAFLD children, and 15 healthy children, were enrolled in this study at Shenzhen Children's Hospital. All of them underwent magnetic resonance spectroscopy (MRS) to quantify the liver fat fraction. Stool samples were collected and analysed with metagenomics. According to body mass index (BMI) and MRS proton density fat fraction (MRS-PDFF), we divided the participants into BMI groups, including the AW group (n = 43) and the Lean group (n = 15); MRS groups, including the NAFLD group (n = 27) and the Control group (n = 31); and BMI-MRS 3 groups, including NAFLD_AW (AW children with NAFLD) (n = 27), Ctrl_AW (n = 16) (AW children without NAFLD) and Ctrl_Lean (n = 15). There was no difference in sex or age among those groups (p > 0.05). In the BMI groups, at the genus level, Dialister, Akkermansia, Odoribacter, and Alistipes exhibited a significant decrease in AW children compared with the Lean group. At the species level, Megamonas hypermegale was increased in the AW group, while Akkermansia muciniphila, Dialister invisus, Alistipes putredinis, Bacteroides massiliensis, Odoribacter splanchnicus, and Bacteroides thetaiotaomicron were decreased in AW children, compared to the Lean group. Compared with the Control group, the genus Megamonas, the species of Megamonas hypermegale and Megamonas rupellensis, increased in the NAFLD group. Furthermore, the genus Megamonas was enriched in the NAFLD_AW group, while Odoribacter, Alistipes, Dialister, and Akkermansia were depleted compared with the Ctrl_Lean or Ctrl_AW group at the genus level. Megamonas hypermegale and Megamonas rupellensis exhibited a significant increase in NAFLD_AW children compared with the Ctrl_Lean or Ctrl_AW group at the species level. Compared with healthy children, the pathways of P461-PWY contributed by the genus Megamonas were significantly increased in NAFLD_AW. We found that compared to healthy children, the genus Megamonas was enriched, while Megamonas hypermegale and Megamonas rupellensis were enriched at the species level in children and adolescents with NAFLD. This indicates that the NAFLD status and/or diet associated with NAFLD patients might lead to the enrichment of the genus Megamonas or Megamonas species.

Gut microbiome is associated with metabolic syndrome accompanied by elevated gamma-glutamyl transpeptidase in men

It is predicted that by 2035, metabolic syndrome (MS) will be found in nearly more than half of our adult population, seriously affecting the health of our body. MS is usually accompanied by the occurrence of abnormal liver enzymes, such as elevated gamma-glutamyl transpeptidase (GGT). More and more studies have shown that the gut microbiota is involved in MS; however, the correlation between gut microbiota and MS with elevated GGT has not been studied comprehensively. Especially, there are few reports about its role in the physical examination of the population of men with MS and elevated GGT. By using the whole-genome shotgun sequencing technology, we conducted a genome-wide association study of the gut microbiome in 66 participants diagnosed as having MS accompanied by high levels of GGT (case group) and 66 participants with only MS and normal GGT level (control group). We found that the number of gut microbial species was reduced in participants in the case group compared to that of the control group. The overall microbial composition between the two groups is of significant difference. The gut microbiota in the case group is characterized by increased levels of “harmful bacteria” such as Megamonas hypermegale, Megamonas funiformis, Megamonas unclassified, Klebsiella pneumoniae, and Fusobacterium mortiferum and decreased levels of “beneficial bacteria” such as Faecalibacterium prausnitzii, Eubacterium eligens, Bifidobacterium longum, Bifidobacterium pseudocatenulatum, Bacteroides dorei, and Alistipes putredinis. Moreover, the pathways of POLYAMSYN-PWY, ARG+POLYAMINE-SYN, PWY-6305, and GOLPDLCAT-PWY were also increased in the case group, which may play a role in the elevation of GGT by producing amine, polyamine, putrescine, and endogenous alcohol. Taken together, there are apparent changes in the composition of the gut microbiome in men with MS and abnormal GGT levels, and it is high time to discover specific gut microbiome as a potential therapeutic target in that population. More in-depth studies of relevant mechanism could offer some new methods for the treatment of MS with elevated GGT.

Intestinal ‘Infant-Type’ Bifidobacteria Mediate Immune System Development in the First 1000 Days of Life

Immune system maturation begins early in life, but few studies have examined how early-life gut microbiota colonization educates the neonatal immune system. Bifidobacteria predominate in the intestines of breastfed infants and metabolize human milk oligosaccharides. This glycolytic activity alters the intestinal microenvironment and consequently stimulates immune system maturation at the neonatal stage. However, few studies have provided mechanistic insights into the contribution of ‘infant-type’ Bifidobacterium species, especially via metabolites such as short-chain fatty acids. In this review, we highlight the first 1000 days of life, which provide a window of opportunity for infant-type bifidobacteria to educate the neonatal immune system. Furthermore, we discuss the instrumental role of infant-type bifidobacteria in the education of the neonatal immune system by inducing immune tolerance and suppressing intestinal inflammation, and the potential underlying mechanism of this immune effect in the first 1000 days of life. We also summarize recent research that suggests the administration of infant-type bifidobacteria helps to modify the intestinal microecology and prevent the progress of immune-mediated disorders.

Pivotal Dominant Bacteria Ratio and Metabolites Related to Healthy Body Index Revealed by Intestinal Microbiome and Metabolomics

Various body indexes, especially body fat percentage (BFP), are widely used as effective indicators to measure our health. BFP is used in medicine to assess obesity, which is a body fat mass disorder accompanied with changes of the gut microbiota. However, the relationship between BFP and the gut microbiota has not been studied so far. To address this problem, we examined how gut microbiota and metabolome associated with body indices in healthy people. Microbial and metabolomics data based on 16S rDNA sequencing and LC-MS were obtained from stool samples of 20 healthy adults. Bioinformatics analysis was performed to explore the correlations between the body indices and gut microbial characteristics. Significantly different microbes were further validated via qPCR. Differential characteristics were filtered by building machine learning models to predict body status. Our data showed that abundance of Prevotella and the Prevotella/Bacteroides (P/B) ratio in the gut were markedly higher in high-BFP individuals than in low-BFP individuals. Microbial and metabolomics data consistently suggested significant differences in fatty acid metabolism in stool samples from the two groups. The P/B ratio and fatty acids are discriminative for people with different index levels by cross validation tests with machine learning models. These results suggest using Prevotella and fecal fatty acids as predictors may offer an alternative method for evaluating health status or weight loss.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s12088-021-00989-5.

The Gut Microbial Signature of Gestational Diabetes Mellitus and the Association With Diet Intervention

Gestational diabetes mellitus (GDM) is a high-risk pregnancy complication that is associated with metabolic disorder phenotypes, such as abnormal blood glucose and obesity. The link between microbiota and diet management contributes to metabolic homeostasis in GDM. Therefore, it is crucial to understand the structure of the gut microbiota in GDM and to explore the effect of dietary management on the microbiota structure. In this study, we analyzed the composition of the gut microbiota between 27 GDM and 30 healthy subjects at two time points using Illumina HiSeq 2500 platform. The taxonomy analyses suggested that the overall bacteria clustered by diabetes status, rather than diet intervention. Of particular interest, the phylum Acidobacteria in GDM was significantly increased, and positively correlated with blood glucose levels. Moreover, Partial least-squares discriminant analysis (PLS-DA) revealed that certain genera in the phyla Firmicutes, Bacteroidetes, Proteobacteria, and Lentisphaerae characterized the GDM gut microbiota. Correlation analysis indicated that blood glucose levels and BMI index were correlated with the relative abundance of SCFAS-producing genera. Through the comparison between the GDM and healthy samples with or without diet intervention, we discovered that the role of short-term diet management in GDM processes is associated with the change in the Firmicutes/Bacteroidetes ratio and some specific taxa, rather than an alternative gut microbial pattern. Our study have important implications for understanding the beneficial effects of diet intervention on the specific gut microbiota and thus possibly their metabolism in pregnant women with GDM.

Intestinal Barrier and Permeability in Health, Obesity and NAFLD

The largest surface of the human body exposed to the external environment is the gut. At this level, the intestinal barrier includes luminal microbes, the mucin layer, gastrointestinal motility and secretion, enterocytes, immune cells, gut vascular barrier, and liver barrier. A healthy intestinal barrier is characterized by the selective permeability of nutrients, metabolites, water, and bacterial products, and processes are governed by cellular, neural, immune, and hormonal factors. Disrupted gut permeability (leaky gut syndrome) can represent a predisposing or aggravating condition in obesity and the metabolically associated liver steatosis (nonalcoholic fatty liver disease, NAFLD). In what follows, we describe the morphological-functional features of the intestinal barrier, the role of major modifiers of the intestinal barrier, and discuss the recent evidence pointing to the key role of intestinal permeability in obesity/NAFLD.

Differential Effect of Light and Dark Period Sleep Fragmentation on Composition of Gut Microbiome and Inflammation in Mice

Bi-directional interactions amongst the gut microbiota, immune system, and brain function are thought to be critical mediators of health and disease. The role sleep plays in mediating these interactions is not known. We assessed the effects of sleep fragmentation (SF) on the microbiota–gut–brain axis. Male C57BL/6NCrl mice (4 to 5 per cage, fed standard lab chow) experienced SF via mechanical stimulation at 2 min intervals during the light (SF) and dark (DD, dark disturbances) periods. Home cage (HC) controls were undisturbed. After 10 days, fecal samples were collected at light onset, midday, light offset, and midnight. Samples were also collected after 10 days without SF. Subsequently, the mice were randomized across groups and allowed 20 additional days of recovery followed by 10 days of SF or DD. To assess effects on the microbiota, 16S rRNA sequencing was used, and mesenteric lymph nodes (MLNs) and cortex and medial prefrontal cortex were analyzed using cytokine arrays. SF and DD produced significant alterations in the microbiota compared to HC, and DD had greater impact than SF on some organisms. SF produced marked suppression in MLNs of chemokines that regulate inflammation (CCL3, CCL4 and their receptor CCR5) and maintain the immune mucosal barrier (Cxcl13) at the same time that cortical cytokines (IL-33) indicated neuroinflammation. DD effects on immune responses were similar to HC. These data suggest that SF alters the microbiome and suppresses mucosal immunity at the same time that mediators of brain inflammation are upregulated. The translational implications for potential application to clinical care are compelling.

Exploiting the Metabolism of the Gut Microbiome as a Vehicle for Targeted Drug Delivery to the Colon

The prevalence of colon-associated diseases has increased significantly over the past several decades, as evidenced by accumulated literature on conditions such as Crohn’s disease, irritable bowel syndrome, colorectal cancer, and ulcerative colitis. Developing therapeutics for these diseases is challenging due to physiological barriers of the colon, systemic side effects, and the intestinal environment. Therefore, in a search for novel methods to overcome some of these problems, researchers discovered that microbial metabolism by gut microbiotia offers a potential method for targeted drug delivery This overview highlights several drug delivery systems used to modulate the microbiota and improve colon-targeted drug delivery. This technology will be important in developing a new generation of therapies which harness the metabolism of the human gut microflora.

Xanthohumol Requires the Intestinal Microbiota to Improve Glucose Metabolism in Diet-Induced Obese Mice

SCOPE

The polyphenol xanthohumol (XN) improves dysfunctional glucose and lipid metabolism in diet-induced obesity animal models. Because XN changes intestinal microbiota composition, the study hypothesizes that XN requires the microbiota to mediate its benefits.

METHODS AND RESULTS

To test the hypothesis, the study feeds conventional and germ-free male Swiss Webster mice either a low-fat diet (LFD, 10% fat derived calories), a high-fat diet (HFD, 60% fat derived calories), or a high-fat diet supplemented with XN at 60 mg kg-1 body weight per day (HXN) for 10 weeks, and measure parameters of glucose and lipid metabolism. In conventional mice, the study discovers XN supplementation decreases plasma insulin concentrations and improves Homeostatic Model Assessment of Insulin Resistance (HOMA-IR). In germ-free mice, XN supplementation fails to improve these outcomes. Fecal sample 16S rRNA gene sequencing analysis suggests XN supplementation changes microbial composition and dramatically alters the predicted functional capacity of the intestinal microbiota. Furthermore, the intestinal microbiota metabolizes XN into bioactive compounds, including dihydroxanthohumol (DXN), an anti-obesogenic compound with improved bioavailability.

CONCLUSION

XN requires the intestinal microbiota to mediate its benefits, which involves complex diet-host-microbiota interactions with changes in both microbial composition and functional capacity. The study results warrant future metagenomic studies which will provide insight into complex microbe-microbe interactions and diet-host-microbiota interactions.

Intestinal, liver and lipid disorders in genetically obese rats are more efficiently reduced by dietary milk thistle seeds than their oil

We hypothesized that milk thistle seed or seed oil dietary supplementation reduces intestinal, liver and lipid disorders specific to genetic obesity, and the seeds can be more efficient in doing so. Lean and obese male Zucker rats were allocated to 4 groups: the lean (LC) and obese control (OC) groups fed a standard diet and the other 2 obese groups fed a diet supplemented with milk thistle seed oil (O + MTO) or milk thistle seeds (O + MTS). After 5 weeks of feeding, the cecal SCFA pool was slightly and significantly lower in OC and O + MTO compared with LC and O + MTS. The liver fat content was greater in OC, O + MTO and O + MTS compared with LC; however, it was significantly lower in O + MTS than in OC and O + MTO. The plasma cholesterol was greater in OC compared with LC, O + MTO and O + MTS; however, it was significantly greater in O + MTO and O + MTS compared with LC. The plasma bilirubin was detected in OC and O + MTO, whereas it was not present in LC and O + MTS. Milk thistle seeds can improve fermentation events in the distal intestine and reduce other disorders specific to genetically obese rats, and the seed PUFAs are responsible for that to a lesser extent.

Inflammatory Mediators and Gut Microbial Toxins Drive Colon Tumorigenesis by IL-23 Dependent Mechanism

Simple Summary

Western-style diet, rich in high fat, is the major cause of obesity and enhanced risk of colon cancer in the USA and worldwide. The inflammatory molecules are a well-established link between obesity and the modulation of colon tumorigenesis. In particular, IL-23 plays an important role in the impact of a western-style diet on obesity, the gut microbiome, and colon tumorigenesis. However, the underlying mechanism of IL-23 production for colon tumor progression and whether IL-23 can be a potential target is not clear. Our findings signify the role of pro-tumorigenic innate immune cells, including dendritic cells and macrophages in IL-23 production by bacterial toxins and eicosanoids. IL-23 knockdown in the tumorigenic dendritic cells and macrophages inhibited the colon tumor cell and organoids growth. Taken together, targeting IL-23 may be a promising option for the prevention and treatment of high-fat/obesity-associated colon cancer in clinical trials.

Abstract

Obesity-associated chronic inflammation predisposes colon cancer risk development. Interleukin-23 (IL-23) is a potential inflammatory mediator linking obesity to chronic colonic inflammation, altered gut microbiome, and colon carcinogenesis. We aimed to elucidate the role of pro-inflammatory eicosanoids and gut bacterial toxins in priming dendritic cells and macrophages for IL-23 secretion to promote colon tumor progression. To investigate the association of IL-23 with obesity and colon tumorigenesis, we utilized TCGA data set and colonic tumors from humans and preclinical models. To understand IL-23 production by inflammatory mediators and gut microbial toxins, we performed several in vitro mechanistic studies to mimic the tumor microenvironment. Colonic tumors were utilized to perform the ex vivo experiments. Our findings showed that IL-23 is elevated in obese individuals, colonic tumors and correlated with reduced disease-free survival. In vitro studies showed that IL-23 treatment increased the colon tumor cell self-renewal, migration, and invasion while disrupting epithelial barrier permeability. Co-culture experiments of educated dendritic cells/macrophages with colon cancer cells significantly increased the tumor aggression by increasing the secretory levels of IL-23, and these observations are further supported by ex vivo rat colonic tumor organotypic experiments. Our results demonstrate gut microbe toxins and eicosanoids facilitate IL-23 production, which plays an important role in obesity-associated colonic tumor progression. This newly identified nexus represents a potential target for the prevention and treatment of obesity-associated colon cancer.

Effects of Potential Probiotic Strains on the Fecal Microbiota and Metabolites of D-Galactose-Induced Aging Rats Fed with High-Fat Diet

Both aging and diet play an important role in influencing the gut ecosystem. Using premature senescent rats induced by D-galactose and fed with high-fat diet, this study aims to investigate the effects of different potential probiotic strains on the dynamic changes of fecal microbiome and metabolites. In this study, male Sprague-Dawley rats were fed with high-fat diet and injected with D-galactose for 12 weeks to induce aging. The effect of Lactobacillus plantarum DR7, L. fermentum DR9, and L. reuteri 8513d administration on the fecal microbiota profile, short-chain fatty acids, and water-soluble compounds were analyzed. It was found that the administration of the selected strains altered the gut microbiota diversity and composition, even at the phylum level. The fecal short-chain fatty acid content was also higher in groups that were administered with the potential probiotic strains. Analysis of the fecal water-soluble metabolites revealed that administration of L. plantarum DR7 and L. reuteri 8513d led to higher fecal content of compounds related to amino acid metabolism such as tryptophan, leucine, tyrosine, cysteine, methionine, valine, and lysine; while administration of L. fermentum DR9 led to higher prevalence of compounds related to carbohydrate metabolism such as erythritol, xylitol, and arabitol. In conclusion, it was observed that different strains of lactobacilli can cause difference alteration in the gut microbiota and the metabolites, suggesting the urgency to explore the specific metabolic impact of specific strains on the host.

Safety Evaluation and In vivo Strain-Specific Functionality of Bacillus Strains Isolated from Korean Traditional Fermented Foods

Unveiling and understanding differences in physiological features below the species level may serve as an essential fast-screening tool for selecting strains that can promote a specific probiotic effect. To study the intra-species diversity of Bacillus, a genus with a wide range of enzyme activities and specificity, 190 Bacillus strains were isolated from traditional Korean fermented food products. Altogether, in the preliminary safety screening, 8 of these strains were found negative for lecithinase and hemolysis activity and were selected for further investigations. On the basis of different levels of enzyme functionalities (high or low proteolytic, amylolytic, and lipolytic (PAL) activities), two Bacillus subtilis strains were selected for an in vivo study. Each of the two strains was separately administered at a level of 1 × 10⁸ CFU per day to C57BL/6 mice that were fed 60% high-fat diet ad libitum for 8 weeks, while Xenical, an anti-obesity drug, was used as a positive control in the experimental setup. B. subtilis M34 and B. subtilis GS40a with low and high amylolytic activities, respectively, induced significantly different and contrasting physiological effects. The production of short-chain fatty acids appeared to be closely associated with a shift in the gut microbiota.

Protective and ameliorating effects of probiotics against diet-induced obesity: A review

Diet-induced obesity is one of the major public health concerns all over the world, and obesity also contributes to the development of other chronic diseases such as non-alcoholic fatty acid liver disease, type 2 diabetes mellitus and cardiovascular diseases. Evidence shows that the pathogenesis of obesity and obesity-associated chronic diseases are closely related to dysregulation of lipid metabolism, glucose metabolism and cholesterol metabolism, and oxidative stress, endoplasmic reticulum stress, abnormal gut microbiome and chronic low-grade inflammation. Recently, in view of potential effects on lipid metabolism, glucose metabolism, cholesterol metabolism and intestinal microbiome, as well as anti-oxidative and anti-inflammatory activities, natural probiotics, including live and dead probiotics, and probiotic components and metabolites, have attracted increasing attention and are considered as novel strategies for preventing and ameliorating obesity and obesity-related chronic diseases. Specifically, this review is presented on the anti-obesity effects of probiotics and underlying molecular mechanisms, which will provide a theoretical basis of anti-obesity probiotics for the development of functional foods.

Cross-sectional comparisons of gut microbiome and short-chain fatty acid levels among children with varied weight classifications

BACKGROUND

Limited studies associate changes in microbiota composition and metabolites among children and adolescents with obesity. Decreases in compositional diversity, increases in the proportion of Firmicutes and Bacteroidetes (F/B ratio) and increases in short-chain fatty acids (SCFAs) have been proposed as contributing factors in the pathophysiology of obesity.

OBJECTIVES

The aim of the current study was to characterize the faecal microbiota composition, diversity, F/B ratio and SCFA levels in different weight categories (lean, overweight, obesity classes 1-3) of children ages 5 to 12 years.

METHODS

We collected and processed 83 samples from different weight categories (27.7% lean, 11% overweight, 15%, 17% and 17% of obesity classes 1, 2, and 3, respectively). Microbiota content was determined by sequencing the V4 region of the 16S rRNA gene, and SCFA content was analyzed.

RESULTS

Microbiota compositions showed no significant differences in diversity or F/B ratios between weight categories. However, a relative abundance of Proteobacteria and lack of Verrucomicrobia were demonstrated when comparing severe obesity to the leaner groups. Faecal butyrate, propionate and isopentanoate concentrations increased progressively with weight category demonstrating significance in the class 3 obesity group.

CONCLUSIONS

Our results show that severe childhood obesity in our study population was associated with changes in gut microbiome composition correlated to previously reported cardiometabolic disease states in obesity. Increased SCFA levels correlate with obesity-related microbiome metabolic function without a reduction in diversity characterized at a phyla level. Further characterization of these specimens at a species level and longitudinal studies are needed to elucidate these relationships.

Dietary Fibre Modulates the Gut Microbiota

Dietary fibre has long been established as a nutritionally important, health-promoting food ingredient. Modern dietary practices have seen a significant reduction in fibre consumption compared with ancestral habits. This is related to the emergence of low-fibre “Western diets” associated with industrialised nations, and is linked to an increased prevalence of gut diseases such as inflammatory bowel disease, obesity, type II diabetes mellitus and metabolic syndrome. The characteristic metabolic parameters of these individuals include insulin resistance, high fasting and postprandial glucose, as well as high plasma cholesterol, low-density lipoprotein (LDL) and high-density lipoprotein (HDL). Gut microbial signatures are also altered significantly in these cohorts, suggesting a causative link between diet, microbes and disease. Dietary fibre consumption has been hypothesised to reverse these changes through microbial fermentation and the subsequent production of short-chain fatty acids (SCFA), which improves glucose and lipid parameters in individuals who harbour diseases associated with dysfunctional metabolism. This review article examines how different types of dietary fibre can differentially alter glucose and lipid metabolism through changes in gut microbiota composition and function.

The Association between Early-Life Gut Microbiota and Long-Term Health and Diseases

Early life gut microbiota have been increasingly recognized as major contributors to short and/or long-term human health and diseases. Numerous studies have demonstrated that human gut microbial colonization begins at birth, but continues to develop a succession of taxonomic abundances for two to three years until the gut microbiota reaches adult-like diversity and proportions. Several factors, including gestational age (GA), delivery mode, birth weight, feeding types, antibiotic exposure, maternal microbiome, and diet, influence the diversity, abundance, and function of early life gut microbiota. Gut microbial life is essential for assisting with the digestion of food substances to release nutrients, exerting control over pathogens, stimulating or modulating the immune system, and influencing many systems such as the liver, brain, and endocrine system. Microbial metabolites play multiple roles in these interactions. Furthermore, studies provide evidence supporting that imbalances of the gut microbiota in early life, referred to as dysbiosis, are associated with specific childhood or adult disease outcomes, such as asthma, atopic dermatitis, diabetes, allergic diseases, obesity, cardiovascular diseases (CVD), and neurological disorders. These findings support that the human gut microbiota may play a fundamental role in the risk of acquiring diseases that may be programmed during early life. In fact, it is critical to explore the role of the human gut microbiota in early life.

In vitro colonic fermentation of red kidney beans depends on cotyledon cells integrity and microbiota adaptation

In the present study we investigated the effect of cellular integrity on microbial utilization of proteins and carbohydrates by gut microbiota. Cotyledon cells from red kidney beans with different levels of structural integrity were fermented in-vitro by microbial communities previously adapted to the conditions of ascending, transverse and descending colon. The effect of bacterial adaptation to substrate was also assessed by using microbiota exposed to a diet rich in bean cells. Microscopy analyses indicate that cell integrity was maintained during fermentation. The amount of gas generated and the rate of total gas production was higher in broken cells compared to intact cells which suggest a faster and more extensive utilization of nutrients when cell wall is broken. A significantly higher butyric and propionic acid level was detected in broken cells at the end of the fermentation. Moreover, adapted bacterial communities were more efficient in fermenting bean cells where higher amounts of butyrate were produced in all colon regions independently of sample integrity. Bacterial communities of the distal colon appeared to be the most efficient in carbohydrate and protein fermentation as witnessed by the higher levels of gas, and short chain fatty acids. It was also found that cell integrity and adaptation to bean cells modulate the hierarchy of nutrient utilization, with non-starch polysaccharides preferred over starch and proteins by microbiota exposed to bean cells. Our results demonstrated that structural aspects of foods, such as cell integrity in plant tissues, may modulate nutrients utilization by gut microbiota.

Application of Differential Network Enrichment Analysis for Deciphering Metabolic Alterations

Modern analytical methods allow for the simultaneous detection of hundreds of metabolites, generating increasingly large and complex data sets. The analysis of metabolomics data is a multi-step process that involves data processing and normalization, followed by statistical analysis. One of the biggest challenges in metabolomics is linking alterations in metabolite levels to specific biological processes that are disrupted, contributing to the development of disease or reflecting the disease state. A common approach to accomplishing this goal involves pathway mapping and enrichment analysis, which assesses the relative importance of predefined metabolic pathways or other biological categories. However, traditional knowledge-based enrichment analysis has limitations when it comes to the analysis of metabolomics and lipidomics data. We present a Java-based, user-friendly bioinformatics tool named Filigree that provides a primarily data-driven alternative to the existing knowledge-based enrichment analysis methods. Filigree is based on our previously published differential network enrichment analysis (DNEA) methodology. To demonstrate the utility of the tool, we applied it to previously published studies analyzing the metabolome in the context of metabolic disorders (type 1 and 2 diabetes) and the maternal and infant lipidome during pregnancy.

Prebiotics in vitro digestion by gut microbes, products' chemistry, and clinical relevance

Several investigations have elucidated the chemistry of prebiotics based on their fermentation by the colonic microbes, which release metabolites that are often implicated in host's gut and whole body health. The present study aims at providing a preview of prebiotics and their interactions with the colonic microbiota for a slow fermentation in vitro. The metabolites produced, mainly short chain fatty acids (SCFA), their chemistry, interactions with prebiotic structural mechanisms, and beneficial impacts on the host were also reported. The present review further considers the clinical relevance of the SCFAs produced. It was deduced that the physicochemical properties of prebiotics would influence their colonic fermentation rate, microbial choice, and growth as well as SCFA type and ratios. This will in turn be of utmost clinical significance. KEY POINTS: • Prebiotics affect the composition of gut microorganisms. • The chemistry of short chain fatty acids are described. • Microbial and clinical applications of SCFAs were provided.

Paraprobiotics and Postbiotics of Probiotic Lactobacilli, Their Positive Effects on the Host and Action Mechanisms: A Review

Lactobacilli comprise an important group of probiotics for both human and animals. The emerging concern regarding safety problems associated with live microbial cells is enhancing the interest in using cell components and metabolites derived from probiotic strains. Here, we define cell structural components and metabolites of probiotic bacteria as paraprobiotics and postbiotics, respectively. Paraprobiotics and postbiotics produced from Lactobacilli consist of a wide range of molecules including peptidoglycans, surface proteins, cell wall polysaccharides, secreted proteins, bacteriocins, and organic acids, which mediate positive effect on the host, such as immunomodulatory, anti-tumor, antimicrobial, and barrier-preservation effects. In this review, we systematically summarize the paraprobiotics and postbiotics derived from Lactobacilli and their beneficial functions. We also discuss the mechanisms underlying their beneficial effects on the host, and their interaction with the host cells. This review may boost our understanding on the benefits and molecular mechanisms associated with paraprobiotics and probiotics from Lactobacilli, which may promote their applications in humans and animals.

High-sugar diet intake, physical activity, and gut microbiota crosstalk: Implications for obesity in rats

This study aims to evaluate the effect of long-term high-sugar diet (HSD) intake and regular physical activity on gut microbiota as well as its health impact. Weaned male Wistar rats were fed with standard chow diet (SSD) or HSD ad libitum and subjected or not to regular swimming training with a workload (2% of body weight) for 15 weeks. Feces samples were used on microbiome analysis using 16S rRNA amplicon sequencing. HSD increased body mass, adipose cushions, and the serum levels of triglycerides and VLDL, also changed the bacteria taxons associated with metabolic disorders (increase taxons belonging to Proteobacteria phylum and decrease Pediococcus genus); the swim training reverted these changes. SSD intake increased the abundance of bacteria associated with metabolization of dietary fiber. Training in association with SSD consumption beneficially modulated the microbiota, increasing the Bacteroidetes, Bacteroidaceae, Porphyromonadaceae, Parabacteroides, and Lactobacillaceae, and decreasing the Firmicute/Bacteroidetes ratio; training was not able to maintain this profile in animals SHD-fed. Physical training modulates the gut microbiota reversing the obesogenic response caused by SHD. However, training itself is not efficient for up-regulating the probiotic bacteria in comparison to its association with a balanced diet.

Early life disruption of the microbiota affects organ development and cytokine gene expression in threespine stickleback

The microbiota that inhabits vertebrates exerts strong effects on host physiology and can be crucial to the development of a normal phenotype. This includes development of the immune system, somatic growth and maintenance, and morphogenesis. However, the genetic background of the host can also affect these life history traits. To this end, we investigated the effects of the microbiota on growth, development, and immune gene expression on two populations of threespine stickleback (Gasterosteus aculeatus), one anadromous and one freshwater. We tested the hypotheses that microbial colonization and the genetic background of the host would affect survival, cytokine gene expression, growth, and development. We raised in vitro crosses of stickleback larvae with and without conventional microbiota. We then exposed all these treatments to Vibrio anguillarum, a potential fish pathogen, in a full factorial design. We found stickleback raised without conventional microbiota had smaller swim bladders relative to those raised with conventional microbiota. Stickleback raised with conventional microbiota exhibited small increases in cytokine gene expression. We found no differences in growth or survival regardless of treatment. These results are consistent with other investigations that show microbiota disruption, in early life, can alter host organ and tissue development and immune responses.

Proteome and microbiota analysis highlight Lactobacillus plantarum TWK10 supplementation improves energy metabolism and exercise performance in mice

Lactobacillus plantarum TWK10 (LP10) is a probiotic known to improve endurance exercise performance. Here, we analyze the proteomics and metagenomic changes in a LP10 supplemented mouse model. Male ICR mice were divided into two groups (n = 8) to receive by oral gavage either vehicle or of LP10 for 6 weeks. Proteins changes by LP10 treatment were subjected to the Ingenuity Pathway Analysis (IPA) to provide corroborative evidence for differential regulation of molecular and cellular functions affecting metabolic processes. Fecal samples were obtained from each mouse, and the microbial community profile analyzed by pyrosequencing of the 16S rRNA genes. Of the 880 identified proteins, 25 proteins were significantly downregulated and 44 proteins were significantly upregulated in the LP10 treated compared to vehicle group. LP10 supplementation shift in the gut microbiota to butyrate-producing members and provided from lipid oxidation since peroxisomal fatty acid oxidation in liver.

The Firmicutes/Bacteroidetes Ratio: A Relevant Marker of Gut Dysbiosis in Obese Patients?

The gut microbiota is emerging as a promising target for the management or prevention of inflammatory and metabolic disorders in humans. Many of the current research efforts are focused on the identification of specific microbial signatures, more particularly for those associated with obesity, type 2 diabetes, and cardiovascular diseases. Some studies have described that the gut microbiota of obese animals and humans exhibits a higher Firmicutes/Bacteroidetes ratio compared with normal-weight individuals, proposing this ratio as an eventual biomarker. Accordingly, the Firmicutes/Bacteroidetes ratio is frequently cited in the scientific literature as a hallmark of obesity. The aim of the present review was to discuss the validity of this potential marker, based on the great amount of contradictory results reported in the literature. Such discrepancies might be explained by the existence of interpretative bias generated by methodological differences in sample processing and DNA sequence analysis, or by the generally poor characterization of the recruited subjects and, more particularly, the lack of consideration of lifestyle-associated factors known to affect microbiota composition and/or diversity. For these reasons, it is currently difficult to associate the Firmicutes/Bacteroidetes ratio with a determined health status and more specifically to consider it as a hallmark of obesity.

Comparative analysis and gut bacterial community assemblages of grass carp and crucian carp in new lineages from the Dongting Lake area

Gut microbiota are known to play an important role in health and nutrition of the host and have been attracting an increasing attention. Farming of new lineages of grass carp and crucian carp has been developed rapidly as these species were found to outperform indigenous ones in terms of growth rate and susceptibility to diseases. Despite this rapid development, no studies have addressed the characteristics of their gut microbiota as a potential factor responsible for the improved characteristics. To reveal whether microbiomes of the new lineages are different from indigenous ones, and therefore could be responsible for improved growth features, intestinal microbiota from the new lineages were subjected to high-throughput sequencing. While the phyla Firmicutes, Fusobacteria and Proteobacteria were representing the core bacterial communities that comprised more than 75% in all fish intestinal samples, significant differences were found in the microbial community composition of the new linages versus indigenous fish populations, suggesting the possibility that results in the advantages of enhanced disease resistance and rapid growth for the new fish lineages. Bacterial composition was similar between herbivorous and omnivorous fish. The relative abundance of Bacteroidetes and Actinobacteria was significantly higher in omnivores compared to that of herbivores, whereas Cetobacterium_sp. was abundant in herbivores. We also found that the gut microbiota of freshwater fish in the Dongting lake area was distinct from those of other areas. Network graphs showed the reduced overall connectivity of gut bacteria in indigenous fish, whereas the bacteria of the new fish lineage groups showed hubs with more node degree. A phylogenetic investigation of communities by reconstruction of unobserved states inferred function profile showed several metabolic processes were more active in the new lineages compared to indigenous fish. Our findings suggest that differences in gut bacterial community composition may be an important factor contributing to the rapid growth and high disease resistance of the new fish lineages.

Effect of time-restricted feeding on metabolic risk and circadian rhythm associated with gut microbiome in healthy males

Time-restricted feeding (TRF) confers protection against nutritional challenges that predispose obesity and metabolic risks through involvement of circadian locomotor output cycles protein kaput genes and gut microbiome, but the underlying mechanism is not clearly understood. Therefore, the present study examined the effects of TRF on metabolic markers and circadian rhythm associated with gut microbiota in healthy males. Two groups (TRF, n 56; non-TRF, n 24) of male adults were enrolled. The TRF group provided blood at pre-TRF and post-TRF, while non-TRF one time after 25 d of trial. Serum lipid and liver profiles were determined. Real time-PCR was applied for circadian and inflammatory gene expression. The 16S rRNA genes were sequenced on the Illumina Miseq v3 platform to comprehensively catalogue the composition and abundance of bacteria in stool. We showed that TRF ameliorated the serum lipid and liver profiles of the individuals. In the TRF group, gut microbial richness was significantly enhanced, with enrichment of Prevotellaceae and Bacteroideaceae. TRF enhanced circadian gene expression probably by activation of sirtuin-1, which is positively associated with gut microbiome richness. TRF could be a safe remedy for the prevention of metabolic diseases related to dyslipidaemia, as it regulates circadian rhythm associated with gut microbiome modulation.

Gut microbiota, dietary phytochemicals and benefits to human health

Purpose of the review

In this review, we discuss the roles of the gut microbiota, dietary phytochemicals in improving human health. Recent studies have reported that the human gut microbiota can be altered by dietary phytochemicals including phenolics, carotenoids, and dietary fibers. In addition, both pathogenic and nonpathogenic bacteria show regulatory effects with phytochemicals, suggesting potential synergistic effects in the improvement of human gut health and prevention of chronic diseases.

Recent findings

Numerous studies have been conducted on gut microbial alterations induced by phytochemicals, such as phenolics and carotenoids. Butyrate, a short-chain fatty acid produced via bacterial fermentation in the colon, also shows a significantly beneficial effect in the maintenance of gut microbial homeostasis. However, the molecular mechanisms underlying the effects of diets and the interactions of the gut microorganisms remain poorly understood. The gut microbiome profile changes have been observed in chronic inflammation-induced diseases including colitis, Crohn's disease, immune dysfunction, colon cancer, obesity and diabetes. The anti-inflammatory effects of dietary phytochemicals against these diseases may be partially mediated by regulation of microbial profiles. Latest advances in biomedical technology such as the next-generation sequencing (NGS), and continuous cost reduction associated with these technologies, enabled researchers to perform ever-increasing number of large-scale, high-throughput computational analyses to elucidate the potential mechanism of phytochemical-microbiome interactions.

Summary

Information obtained from these studies may provide valuable insights to guide future clinical research for the development of therapeutics, botanicals and drug efficacy testing, many of which will be discussed in this review.

Response of Beef Cattle Fecal Microbiota to Grazing on Toxic Tall Fescue

Tall fescue, the predominant southeastern United States cool-season forage grass, frequently becomes infected with an ergot alkaloid-producing toxic endophyte, Epichloë coenophialum Consumption of endophyte-infected fescue results in fescue toxicosis (FT), a condition that lowers beef cow productivity. Limited data on the influence of ergot alkaloids on rumen fermentation profiles or ruminal bacteria that could degrade the ergot alkaloids are available, but how FT influences the grazing bovine fecal microbiota or what role fecal microbiota might play in FT etiology and associated production losses has yet to be investigated. Here, we used 16S rRNA gene sequencing of fecal samples from weaned Angus steers grazing toxic endophyte-infected (E+; n = 6) or nontoxic (Max-Q; n = 6) tall fescue before and 1, 2, 14, and 28 days after pasture assignment. Bacteria in the Firmicutes and Bacteroidetes phyla comprised 90% of the Max-Q and E+ steer fecal microbiota throughout the trial. Early decreases in the Erysipelotrichaceae family and delayed increases of the Ruminococcaceae and Lachnospiraceae families were among the major effects of E+ grazing. E+ also increased abundances within the Planctomycetes, Chloroflexi, and Proteobacteria phyla and the Clostridiaceae family. Multiple operational taxonomic units classified as Ruminococcaceae and Lachnospiraceae were correlated negatively with weight gains (lower in E+) and positively with respiration rates (increased by E+). These data provide insights into how E+ grazing alters the Angus steer microbiota and the relationship of fecal microbiota dynamics with FT.IMPORTANCE Consumption of E+ tall fescue has an estimated annual $1 billion negative impact on the U.S. beef industry, with one driver of these costs being lowered weight gains. As global agricultural demand continues to grow, mitigating production losses resulting from grazing the predominant southeastern United States forage grass is of great value. Our investigation of the effects of E+ grazing on the fecal microbiota furthers our understanding of bovine fescue toxicosis in a real-world grazing production setting and provides a starting point for identifying easy-to-access fecal bacteria that could serve as potential biomarkers of animal productivity and/or FT severity for tall fescue-grazing livestock.

Monosodium L-glutamate and fats change free fatty acid concentrations in intestinal contents and affect free fatty acid receptors express profile in growing pigs

Background

Obesity and its related metabolic syndrome continue to be major public health problems. Monosodium L-glutamate (MSG) may cause metabolic diseases such as obesity. Meanwhile, the Chinese population has undergone rapid transition to a high-fat diet. There is little information available on the effect of MSG and fat alone, or in combination, on free fatty acids (FFAs), lipid metabolism and FFA receptors.

Objective

The aim of this study was to evaluate the effects of MSG and fat alone, or in combination, on intestinal luminal FFAs and expression of gastrointestinal FFA receptors. The aim was also to test whether dietary fat and/or MSG could affect expression of genes related to fatty acid metabolism.

Design

A total of 32 growing pigs were used and fed with four iso-nitrogenous and iso-caloric diets. Pigs in the four treatments received diets with one of two fat concentrations levels (4.4 and 9.4%) and one of two MSG dose levels (0 and 3%), in which most of the fat were brought by soybean oil. The concentration of short chain fatty acids (SCFAs) in cecum and colon, long chain fatty acids (LCFAs) in ileum, cecum and colon, and FFAs receptors expression in hypothalamus and gastrointestinal tract were determined.

Results

MSG and/or fat changed intestinal luminal SCFAs, levels of LCFAs, and showed an antagonistic effect on most of LCFAs. Simultaneously, MSG and/or fat decreased the expression of FFA receptors in hypothalamus and gastrointestinal tract. MSG and/or fat promoted fat deposition through different ways in back fat.

Conclusion

Our results support that MSG and/or fat can alter intestinal luminal FFAs composition and concentration, especially LCFAs, in addition, the expression of FFA receptors in ileum and hypothalamus could be decreased. Moreover, MSG and/or fat can promote protein deposition in back fat, and affect the distribution and metabolism of fatty acids in the body tissues and the body’s ability to perceive fatty acids; these results provide a reference for the occurrence of fat deposition and obesity caused by high-fat and monosodium glutamate diet.