Parabacteroides distasonis ameliorates insulin resistance via activation of intestinal GPR109a

Fucoidan ameliorates alcohol-induced liver injury in mice through Parabacteroides distasonis-mediated regulation of the gut-liver axis

Polysaccharides can benefit the liver via modulation of the gut microbiota, but the exact mechanism is still unclear. This study demonstrated that the effect of Scytosiphon lomentaria fucoidan (SLF) on alcohol-induced liver injury can be closely related to the level of Parabacteroides distasonis (Pd) via in vivo and in vitro models. Further mice experiment showed that Pd alleviated liver injury and inflammation by suppressing the NF-κB/MAPK pathways and activating Nrf2 pathway. The underlying mechanism can be closely associated with modulation of the gut microbiota, particularly an increase in microbiota diversity and beneficial bacteria and a reduction in Proteobacteria. Targeted metabolomics indicated that Pd ameliorated alcohol-induced dysbiosis of microbiota metabolites profile, primarily affecting amino acid metabolism. Moreover, Pd reduced the level of total bile acids (BAs) and improved BAs profile, affecting the expression levels of BA-associated genes in the liver and ileum involved in BA synthesis, transport, and reabsorption. This study suggests that SLF can benefit alcohol-induced liver injury via P. distasonis-mediated regulation of the gut-liver axis.

High-fat diet promotes type 2 diabetes mellitus by disrupting gut microbial rhythms and short-chain fatty acid synthesis

Diabetes ranks among the top 10 causes of death globally, with over 90% of individuals diagnosed with diabetes having type 2 diabetes mellitus (T2DM). It is acknowledged that a high-fat diet (HFD) poses a serious risk for T2DM. The imbalance of intestinal flora, mediated by HFD, can potentially exacerbate the onset and progression of T2DM. However, the impact of HFD on pathological indicators and the intestinal microbiome in the development of T2DM has not been systematically investigated. Therefore, a HFD mouse model and a T2DM mouse model were established, respectively, in this study. The role of HFD as a driving factor in the development of T2DM was assessed using various measures, including basic pathological indicators of T2DM, lipid metabolism, liver oxidative stress, intestinal permeability, levels of inflammatory factors, gut microbiota, and short-chain fatty acids (SCFAs). The findings indicated that HFD could influence the aforementioned measures to align with T2DM changes, but the contribution of HFD varied across different pathological metrics of T2DM. The impact of HFD on low-density lipoprotein cholesterol, glutathione peroxidase, malondialdehyde, and tumor necrosis factor-α did not show a statistically significant difference from those observed in T2DM during its development. In addition, regarding gut microbes, HFD primarily influenced the alterations in bacteria capable of synthesizing SCFAs. The notable decrease in SCFA content in both serum and cecal matter further underscored the effect of HFD on SCFA-synthesising bacteria in mice. Hence, this research provided a systematic assessment of HFD's propelling role in T2DM's progression. It was inferred that gut microbes, particularly those capable of synthesizing SCFAs, could serve as potential targets for the future prevention and treatment of T2DM instigated by HFD.

Effects of Clostridium butyricum and inulin supplementation on intestinal microbial composition in high-fat diet fed mice

Obesity has become a serious epidemic problem in the world, and probiotics and prebiotics have been used to treat obesity. The effectiveness of diet therapy such as Clostridium butyricum (CB) and inulin supplementation in obesity and whether they can cooperate to produce better effects are still unclear. And during this process, intestinal flora play an important role, while the bacteria involved and the metabolic mechanism need to be explored. In this study, we successfully established a mouse obesity model with a high-fat diet (HFD) and divided it into three experimental groups: 7% CB (CB7), 7% CB + 1% inulin (C7G1), and 10% CB + 1% inulin (C10G). Dietary supplementation with CB and inulin could improve the glucose tolerance and intestinal microbial composition of obese mice, among which the simultaneous supplementation with 7% CB and 1% inulin (C7G1) has the most significant effect on obese mice fed with a HFD. It could significantly reduce the amount of total cholesterol, triglyceride, and low-density lipoprotein, improve abnormal glucose tolerance, and reduce abnormal blood glucose in obese mice. The intestinal flora of obese mice changed significantly, among which Lachnospiraceae_unclassified, Porphyromonaceae_unclassified, Olsenella, Bacteria_unclassified and Clostridiales_unclassified decreased due to the HFD, while Megamonas and Clostridium XIVa increased. After the supplementation with CB and inulin, the enrichment of three kinds of beneficial bacteria, Parabacteroides, Bacteroides, and Ruminococcaceae unclassified increased. The high-fat diet could upregulate the expression of FGF21, and the Clostridium butyricum and inulin supplemented diet could decrease the upregulation.

Arabinoxylan Alleviates Obesity by Regulating Gut Microbiota and Bile Acid Metabolism

Overweight and obesity are major and increasingly global public health concern. High intake of dietary fiber is negatively correlated with obesity and obesity-related metabolic diseases. Here, we investigated the impact of arabinoxylan on obesity based on the modification of gut microecology. Arabionxylan reduced body weight and improved glucose metabolism, as well as intestinal barrier function and metabolic endotoxemia in obese mice. Supplementation with arabinoxylan increased the relative abundance of Prevotellaceae_UCG_001, Lachnospiraceae_NK4A136_group, Clostridia_UCG_014, Alistipes, Bacteroides, and Ruminococcus, which was associated with the upregulated 7α-dehydroxylation function and production of secondary bile acids (deoxycholic acid and lithocholic acid). The modification of gut microbiota by arabinoxylan also influenced the production of SCFAs, genistein, daidzein, indolelactic acid, and indoleacetic acid, contributing to the amelioration of obesity. Our study highlights the antiobesity effects of arabinoxylan through the modification of gut microbiota and the production of bioactive metabolites.

The general glycan profiling of Dendrobium officinale and their protective effects on MIN6 cells via ERK signaling pathway

Based on structural elucidation of natural and hydrolyzed glycans, the general glycans profiling of D. officinale were unequivocally established for the first time as follows: The results indicated that the structure of D. officinale glycans with low degree of polymerization (DP ≤ 22) was linear α-D-1,4-glucan, whereas the structure of glycans with high degree of polymerization (DP > 24) was linear acetylated 1,4-glucomannan. The content of acetyl groups and mannose to glucose (M/G) ratio increased with the degree of polymerization of D. officinale glycans. In addition, this study showed that natural D. officinale glycans protected pancreatic β-cell damage induced by glucotoxicity through the extracellular signal-regulated kinase (ERK)1/2 pathway.

Increased intestinal permeability and lipopolysaccharide contribute to swainsonine-induced systemic inflammation

Long-term consumption of swainsonine could be poisonous to livestock, including facilitating apoptosis by impairing lysosomal function and inhibiting autophagic degradation, leading to liver inflammation and even death in livestock. However, the mechanism by swainsonine induced systemic inflammatory responses remained unclear, especially the effects of swainsonine on intestinal permeability, lipopolysaccharide (LPS) level and oxidative stress response were unknown. In this study, swainsonine increased intestinal permeability as evidenced by the significant down-regulation of colonic goblet cells, Akkermansia muciniphila and intestinal tight junction protein Occludin, Claudin 1 and ZO-1, and the significant up-regulation of mRNA expression level of the intestinal permeability indicator protein tyrosine phosphatase receptor type H (Ptprh) in the ileum of mice. Simultaneously, the elevated LPS biosynthetic genes in intestinal microbiota and increased intestinal permeability facilitated more bacterial endotoxin LPS to enter the blood. High concentration of free-form LPS induced high levels of proinflammatory cytokines and oxidative stress response, thereby causing the systemic inflammation. These findings provided a new perspective on swainsonine-induced systemic inflammation, suggesting that intestinal permeability and free-form LPS level may be the potential trigger factors.

Bacteroides uniformis degrades β-glucan to promote Lactobacillus johnsonii improving indole-3-lactic acid levels in alleviating colitis

BACKGROUND

Intake of dietary fiber is associated with a reduced risk of inflammatory bowel disease. β-Glucan (BG), a bioactive dietary fiber, has potential health-promoting effects on intestinal functions; however, the underlying mechanism remains unclear. Here, we explore the role of BG in ameliorating colitis by modulating key bacteria and metabolites, confirmed by multiple validation experiments and loss-of-function studies, and reveal a novel bacterial cross-feeding interaction.

RESULTS

BG intervention ameliorates colitis and reverses Lactobacillus reduction in colitic mice, and Lactobacillus abundance was significantly negatively correlated with the severity of colitis. It was confirmed by further studies that Lactobacillus johnsonii was the most significantly enriched Lactobacillus spp. Multi-omics analysis revealed that L. johnsonii produced abundant indole-3-lactic acid (ILA) leading to the activation of aryl hydrocarbon receptor (AhR) responsible for the mitigation of colitis. Interestingly, L. johnsonii cannot utilize BG but requires a cross-feeding with Bacteroides uniformis, which degrades BG and produces nicotinamide (NAM) to promote the growth of L. johnsonii. A proof-of-concept study confirmed that BG increases L. johnsonii and B. uniformis abundance and ILA levels in healthy individuals.

CONCLUSIONS

These findings demonstrate the mechanism by which BG ameliorates colitis via L. johnsonii-ILA-AhR axis and reveal the important cross-feeding interaction between L. johnsonii and B. uniformis. Video Abstract.

Interactions between Gut Microbiota and Natural Bioactive Polysaccharides in Metabolic Diseases: Review

The gut microbiota constitutes a complex ecosystem, comprising trillions of microbes that have co-evolved with their host over hundreds of millions of years. Over the past decade, a growing body of knowledge has underscored the intricate connections among diet, gut microbiota, and human health. Bioactive polysaccharides (BPs) from natural sources like medicinal plants, seaweeds, and fungi have diverse biological functions including antioxidant, immunoregulatory, and metabolic activities. Their effects are closely tied to the gut microbiota, which metabolizes BPs into health-influencing compounds. Understanding how BPs and gut microbiota interact is critical for harnessing their potential health benefits. This review provides an overview of the human gut microbiota, focusing on its role in metabolic diseases like obesity, type II diabetes mellitus, non-alcoholic fatty liver disease, and cardiovascular diseases. It explores the basic characteristics of several BPs and their impact on gut microbiota. Given their significance for human health, we summarize the biological functions of these BPs, particularly in terms of immunoregulatory activities, blood sugar, and hypolipidemic effect, thus providing a valuable reference for understanding the potential benefits of natural BPs in treating metabolic diseases. These properties make BPs promising agents for preventing and treating metabolic diseases. The comprehensive understanding of the mechanisms by which BPs exert their effects through gut microbiota opens new avenues for developing targeted therapies to improve metabolic health.

Bacterial extracellular vesicles: Vital contributors to physiology from bacteria to host

Bacterial extracellular vesicles (bEVs) represent spherical particles with diameters ranging from 20 to 400 nm filled with multiple parental bacteria-derived components, including proteins, nucleic acids, lipids, and other biomolecules. The production of bEVs facilitates bacteria interacting with their environment and exerting biological functions. It is increasingly evident that the bEVs play integral roles in both bacterial and host physiology, contributing to environmental adaptations to functioning as health promoters for their hosts. This review highlights the current state of knowledge on the composition, biogenesis, and diversity of bEVs and the mechanisms by which different bEVs elicit effects on bacterial physiology and host health. We posit that an in-depth exploration of the mechanistic aspects of bEVs activity is essential to elucidate their health-promoting effects on the host and may facilitate the translation of bEVs into applications as novel natural biological nanomaterials.

Analysis of the key genes of Lactobacillus reuteri strains involved in the protection against alcohol-induced intestinal barrier damage

Gastrointestinal inflammation and intestinal barrier function have important effects on human health. Alcohol, an important foodborne hazard factor, damages the intestinal barrier, increasing the risk of disease. Lactobacillus reuteri strains have been reported to reduce gastrointestinal inflammation and strengthen the intestinal barrier. In this study, we selected three anti-inflammatory L. reuteri strains to evaluate their role in the protection of the intestinal barrier and their immunomodulatory activity in a mouse model of gradient alcohol intake. Among the three strains tested (FSCDJY33M3, FGSZY33L6, and FCQHCL8L6), L. reuteri FSCDJY33M3 was found to protect the intestinal barrier most effectively, possibly due to its ability to reduce the expression of interleukin (IL)-1β, IL-6, and tumor necrosis factor-alpha (TNF-α) and increase the expression of tight junction proteins (occludin, claudin-3). Genomic analysis suggested that the protective effects of L. reuteri FSCDJY33M3 may be related to functional genes and glycoside hydrolases associated with energy production and conversion, amino acid transport and metabolism, carbohydrate transport and metabolism, and DNA replication, recombination, and repair. These genes include COG2856, COG1804, COG2071, and COG1061, which encode adenine deaminase, acyl-CoA transferases, glutamine amidotransferase, RNA helicase, and glycoside hydrolases, including GH13_20, GH53, and GH70. Our results identified functional genes that may be related to protection against alcohol-induced intestinal barrier damage, which might be useful for screening lactic acid bacterial strains that can protect the intestinal barrier.

Oat Dietary Fiber Delays the Progression of Chronic Kidney Disease in Mice by Modulating the Gut Microbiota and Reducing Uremic Toxin Levels

Chronic kidney disease (CKD) has emerged as a significant public health concern. In this article, we investigated the mechanism of oat dietary fiber in regulating CKD. Our findings indicated that the gut microbiota of CKD patients promoted gut microbiota dysbiosis and kidney injury in CKD mice. Intervention with oat-resistant starch prepared by ultrasonic combined enzymatic hydrolysis (ORSU) and oat β-glucan with a molecular weight of 5 × 104 Da (OBGM) elevated the levels of short-chain fatty acids (SCFAs) and regulated gut dysbiosis in the gut-humanized CKD mice. ORSU and OBGM also reduced CKD-related uremic toxins such as creatinine, indoxyl sulfate (IS), and p-cresol sulfate (PCS) levels; reinforced the intestinal barrier function of the gut-humanized CKD mice; and mitigated renal inflammation and fibrosis via the NF-κB/TGF-β pathway. Therefore, ORSU and OBGM might delay the progression of CKD by modulating the gut microbiota to reduce uremic toxins levels. Our results explain the mechanism of oat dietary fiber aimed at mitigating CKD.

Valine induces inflammation and enhanced adipogenesis in lean mice by multi-omics analysis

Introduction

The branched-chain amino acids (BCAAs) are essential to mammalian growth and development but aberrantly elevated in obesity and diabetes. Each BCAA has an independent and specific physio-biochemical effect on the host. However, the exact molecular mechanism of the detrimental effect of valine on metabolic health remains largely unknown.

Methods and results

This study showed that for lean mice treated with valine, the hepatic lipid metabolism and adipogenesis were enhanced, and the villus height and crypt depth of the ileum were significantly increased. Transcriptome profiling on white and brown adipose tissues revealed that valine disturbed multiple signaling pathways (e.g., inflammation and fatty acid metabolism). Integrative cecal metagenome and metabolome analyses found that abundances of Bacteroidetes decreased, but Proteobacteria and Helicobacter increased, respectively; and 87 differential metabolites were enriched in several molecular pathways (e.g., inflammation and lipid and bile acid metabolism). Furthermore, abundances of two metabolites (stercobilin and 3-IAA), proteins (AMPK/pAMPK and SCD1), and inflammation and adipogenesis-related genes were validated.

Discussion

Valine treatment affects the intestinal microbiota and metabolite compositions, induces gut inflammation, and aggravates hepatic lipid deposition and adipogenesis. Our findings provide novel insights into and resources for further exploring the molecular mechanism and biological function of valine on lipid metabolism.

Large Yellow Tea Polysaccharide Alleviates HFD-Induced Intestinal Homeostasis Dysbiosis via Modulating Gut Barrier Integrity, Immune Responses, and the Gut Microbiome

Long-term high-fat diet (HFD) will induce dysbiosis and a disturbance of intestinal homeostasis. Large yellow tea polysaccharide (LYP) has been shown to improve obesity-associated metabolic disease via modulation of the M2 polarization. However, the contribution of LYP to intestinal barrier impairment and improvement mechanisms in obesity caused by an HFD are still not clear. In this study, we evaluated the impacts of LYP on the mucosal barrier function and microbiota composition in HFD-feeding mice. Results exhibited that dietary LYP supplement could ameliorate the physical barrier function via maintaining intestinal mucosal integrity and elevating tight-junction protein production, strengthen the chemical barrier function via up-regulating the levels of glucagon-like peptide-1 and increasing mucin-producing goblet cell numbers, and enhance the intestinal immune barrier function though suppressing immune cell subsets and cytokines toward pro-inflammatory phenotypes. Moreover, LYP reshaped the constitution and metabolism of intestinal flora by enriching probiotics that produce short-chain fatty acids. Overall, LYP might be used as a critical regulator of intestinal homeostasis to improve host health by promoting gut barrier integrity, modulating intestinal immune response, and inhibiting bowel inflammation.

Our extended microbiome: The human-relevant metabolites and biology of fermented foods

One of the key modes of microbial metabolism occurring in the gut microbiome is fermentation. This energy-yielding process transforms common macromolecules like polysaccharides and amino acids into a wide variety of chemicals, many of which are relevant to microbe-microbe and microbe-host interactions. Analogous transformations occur during the production of fermented foods, resulting in an abundance of bioactive metabolites. In foods, the products of fermentation can influence food safety and preservation, nutrient availability, and palatability and, once consumed, may impact immune and metabolic status, disease expression, and severity. Human signaling pathways perceive and respond to many of the currently known fermented food metabolites, though expansive chemical novelty remains to be defined. Here we discuss several aspects of fermented food-associated microbes and metabolites, including a condensed history, current understanding of their interactions with hosts and host-resident microbes, connections with commercial probiotics, and opportunities for future research on human health and disease and food sustainability.

Navigating the B vitamins: Dietary diversity, microbial synthesis, and human health

B vitamins are intricately involved in various physiological processes vital for health. Their significance is complicated by the heterogeneous landscape of B vitamin distribution in diets and the contributions of the gut microbiota. Here, we delve into the impact of these factors on B vitamins and introduce strategies, with a focus on microbiota-based therapeutic options, to enhance their availability for improved well-being. Additionally, we provide an ecological and evolutionary perspective on the importance of B vitamins to human-microbiota interactions. In the dynamic realms of nutrition and microbiome science, these essential micronutrients continue to play a fundamental role in our understanding of disease development.

Clonal Parabacteroides from Gut Microfistulous Tracts as Transmissible Cytotoxic Succinate-Commensal Model of Crohn's Disease Complications

Crohn's disease (CD) has been traditionally viewed as a chronic inflammatory disease that cause gut wall thickening and complications, including fistulas, by mechanisms not understood. By focusing on Parabacteroides distasonis (presumed modern succinate-producing commensal probiotic), recovered from intestinal microfistulous tracts (cavernous fistulous micropathologies CavFT proposed as intermediate between 'mucosal fissures' and 'fistulas') in two patients that required surgery to remove CD-damaged ilea, we demonstrate that such isolates exert pathogenic/pathobiont roles in mouse models of CD. Our isolates are clonally-related; potentially emerging as transmissible in the community and mice; proinflammatory and adapted to the ileum of germ-free mice prone to CD-like ileitis (SAMP1/YitFc) but not healthy mice (C57BL/6J), and cytotoxic/ATP-depleting to HoxB8-immortalized bone marrow derived myeloid cells from SAMP1/YitFc mice when concurrently exposed to succinate and extracts from CavFT-derived E. coli , but not to cells from healthy mice. With unique genomic features supporting recent genetic exchange with Bacteroides fragilis -BGF539, evidence of international presence in primarily human metagenome databases, these CavFT Pdis isolates could represent to a new opportunistic Parabacteroides species, or subspecies (' cavitamuralis' ) adapted to microfistulous niches in CD.

mNFE: microbiome network flow entropy for detecting pre-disease states of type 1 diabetes

In the development of Type 1 diabetes (T1D), there are critical states just before drastic changes, and identifying these pre-disease states may predict T1D or provide crucial early-warning signals. Unlike gene expression data, gut microbiome data can be collected noninvasively from stool samples. Gut microbiome sequencing data contain different levels of phylogenetic information that can be utilized to detect the tipping point or critical state in a reliable manner, thereby providing accurate and effective early-warning signals. However, it is still difficult to detect the critical state of T1D based on gut microbiome data due to generally non-significant differences between healthy and critical states. To address this problem, we proposed a new method - microbiome network flow entropy (mNFE) based on a single sample from each individual - for detecting the critical state before seroconversion and abrupt transitions of T1D at various taxonomic levels. The numerical simulation validated the robustness of mNFE under different noise levels. Furthermore, based on real datasets, mNFE successfully identified the critical states and their dynamic network biomarkers (DNBs) at different taxonomic levels. In addition, we found some high-frequency species, which are closely related to the unique clinical characteristics of autoantibodies at the four levels, and identified some non-differential 'dark species' play important roles during the T1D progression. mNFE can robustly and effectively detect the pre-disease states at various taxonomic levels and identify the corresponding DNBs with only a single sample for each individual. Therefore, our mNFE method provides a new approach not only for T1D pre-disease diagnosis or preventative treatment but also for preventative medicine of other diseases by gut microbiome.