Intestinal microbiota via NLRP3 inflammasome dependent neuronal pyroptosis mediates anxiety-like behaviour in mice exposed to 3.5 GHz radiofrequency radiation

The rapid development of 5G communication technology has increased public concern about the potential adverse effects on human health. Till now, the impacts of radiofrequency radiation (RFR) from 5G communication on the central nervous system and gut-brain axis are still unclear. Therefore, we investigated the effects of 3.5 GHz (a frequency commonly used in 5G communication) RFR on neurobehavior, gut microbiota, and gut-brain axis metabolites in mice. The results showed that exposure to 3.5 GHz RFR at 50 W/m2 for 1 h over 35 d induced anxiety-like behaviour in mice, accompanied by NLRP3-dependent neuronal pyroptosis in CA3 region of the dorsal hippocampus. In addition, the microbial composition was widely divergent between the sham and RFR groups. 3.5 GHz RFR also caused changes in metabolites of feces, serum, and brain. The differential metabolites were mainly enriched in glycerophospholipid metabolism, tryptophan metabolism, and arginine biosynthesis. Further correlation analysis showed that gut microbiota dysbiosis was associated with differential metabolites. Based on the above results, we speculate that dysfunctional intestinal flora and metabolites may be involved in RFR-induced anxiety-like behaviour in mice through neuronal pyroptosis in the brain. The findings provide novel insights into the mechanism of 5G RFR-induced neurotoxicity.

Alternations in the human skin, gut and vaginal microbiomes in perimenopausal or postmenopausal Vulvar lichen sclerosus

Vulvar lichen sclerosus (VLS) is a chronic and progressive dermatologic condition that can cause physical dysfunction, disfigurement, and impaired quality of life. However, the etiology of VLS remains unknown. The vulvar skin, intestinal and vaginal microbiomes have been postulated to play important roles in the pathogenesis of this disease. The aim of this study was to compare the compositional characteristics of the vulvar skin, vagina, and gut microbiota between perimenopausal or postmenopausal VLS patients and healthy controls. The study involved six perimenopausal or postmenopausal VLS patients which were based on characteristic clinical manifestations and histologic confirmation and five healthy controls. The pruritus severity of each patient was evaluated using the NRS scale, and the dermatology-specific health-related quality of life was assessed using the Skindex-16. Metagenomic sequencing was performed, and the results were analyzed for alpha and beta diversity. LEfSe analysis were used to investigate the microbial alterations in vulvar skin, gut and vagina. KEGG databases were used to analyze differences in functional abundance. The study found significant differences in alpha diversity between the two groups in stool and vaginal samples (P < 0.05). Patients with VLS had a higher abundance of Enterobacter cloacae, Flavobacterium_branchiophilum, Mediterranea_sp._An20, Parabacteroides_johnsoniiand Streptococcus_bovimastitidis on the vulvar skin, while Corynebacterium_sp._zg-913 was less abundant compared to the control group. The relative abundance of Sphingomonas_sp._SCN_67_18, Sphingobium_sp._Ant17, and Pontibacter_sp_BT213 was significantly higher in the gut samples of patients with VLS.Paenibacillus_popilliae,Gemella_asaccharolytica, and Coriobacteriales_bacterium_DNF00809 compared to the control group. Additionally, the vaginal samples of patients with VLS exhibited a significantly lower relative abundance of Bacteroidales_bacterium_43_8, Bacteroides_sp._CAG:20, Blautia_sp._AM28-10, Fibrobacter_sp._UWB16, Lachnospiraceae_bacterium_AM25-39, Holdemania_filiformis, Lachnospiraceae_bacterium_GAM79, and Tolumonas_sp. Additionally, the butyrate-producing bacterium SS3/4 showed a significant difference compared to the controls. The study found a negative relationship between Sphingobium_sp._Ant17 in stool and Skindex-16 (P < 0.05), while Mediterranea_sp._An20 had a positive correlation with Skindex-16 (P < 0.05) in the skin. Additionally, our functional analysis revealed alterations in Aminoacyl_tRNA_biosynthesis, Glutathione_metabolism, the pentose phosphate pathway, and Alanine__aspartate_and_glutamate_metabolism in the VLS patient group. The study suggests that perimenopausal or postmenopausal patients with VLS have a modified microbiome in the vulvar skin, gut, and vagina. This modification is linked to abnormal energy metabolism, increased oxidative stress, and abnormal amino acid metabolism.

Amino acids in piglet diarrhea: Effects, mechanisms and insights

Piglet diarrhea is among one of the most serious health problems faced by the pig industry, resulting in significant economic losses. Diarrheal disease in piglets has a multifactorial etiology that is affected by physiology, environment, and management strategy. Diarrhea is the most apparent symptom of intestinal dysfunction. As a key class of essential nutrients in the piglet diet, amino acids confer a variety of beneficial effects on piglets in addition to being used as a substrate for protein synthesis, including maintaining appropriate intestinal integrity, permeability and epithelial renewal, and alleviating morphological damage and inflammatory and oxidative stress. Thus, provision of appropriate levels of amino acids could alleviate piglet diarrhea. Most amino acid effects are mediated by metabolites, gut microbes, and related signaling pathways. In this review, we summarize the current understanding of dietary amino acid effects on gut health and diarrhea incidence in piglets, and reveal the mechanisms involved. We also provide ideas for using amino acid blends and emphasize the importance of amino acid balance in the diet to prevent diarrhea in piglets.

Alterations in gut microbiota and host transcriptome of patients with coronary artery disease

BACKGROUND

Coronary artery disease (CAD) is a widespread heart condition caused by atherosclerosis and influences millions of people worldwide. Early detection of CAD is challenging due to the lack of specific biomarkers. The gut microbiota and host-microbiota interactions have been well documented to affect human health. However, investigation that reveals the role of gut microbes in CAD is still limited. This study aims to uncover the synergistic effects of host genes and gut microbes associated with CAD through integrative genomic analyses.

RESULTS

Herein, we collected 52 fecal and 50 blood samples from CAD patients and matched controls, and performed amplicon and transcriptomic sequencing on these samples, respectively. By comparing CAD patients with health controls, we found that dysregulated gut microbes were significantly associated with CAD. By leveraging the Random Forest method, we found that combining 20 bacteria and 30 gene biomarkers could distinguish CAD patients from health controls with a high performance (AUC = 0.92). We observed that there existed prominent associations of gut microbes with several clinical indices relevant to heart functions. Integration analysis revealed that CAD-relevant gut microbe genus Fusicatenibacter was associated with expression of CAD-risk genes, such as GBP2, MLKL, and CPR65, which is in line with previous evidence (Tang et al., Nat Rev Cardiol 16:137-154, 2019; Kummen et al., J Am Coll Cardiol 71:1184-1186, 2018). In addition, the upregulation of immune-related pathways in CAD patients were identified to be primarily associated with higher abundance of genus Blautia, Eubacterium, Fusicatenibacter, and Monoglobus.

CONCLUSIONS

Our results highlight that dysregulated gut microbes contribute risk to CAD by interacting with host genes. These identified microbes and interacted risk genes may have high potentials as biomarkers for CAD.

Structural characterization of slow digestion dextrin synthesized by a combination of α-glucosidase and cyclodextrin glucosyltransferase and its prebiotic potential on the gut microbiota in vitro

Starch-based dietary fibers are at the forefront of functional ingredient research. In this study, a novel water-soluble slow digestion dextrin (SDD) was synthesized by synergy of α-glucosidase and cyclodextrin glucosyltransferase and characterized. Results showed that SDD exhibited high solubility, low viscosity, and resistance to digestive enzymes, and also showed an increased dietary fiber content of 45.7% compared with that of α-glucosidase catalysis alone. Furthermore, SDD was used as the sole carbon source to ferment selected intestinal strains and human fecal microflora in vitro to investigate its prebiotic effects. It was found that SDD could markedly enriched the abundance of Bifidobacterium, Veillonella, Dialister, and Blautia in human gut microflora and yielded higher total organic acid. The combination of α-glucosidase and cyclodextrin glucosyltransferase in this study showed valuable potential for the preparation of a novel slow digestion dextrin with good physicochemical properties and improved prebiotic effects.

Natural products targeting Nrf2/ARE signaling pathway in the treatment of inflammatory bowel disease

Inflammatory bowel disease (IBD) is a special chronic intestinal inflammatory disease, which is mainly divided into Crohn's disease (CD) and ulcerative colitis (UC). Its occurrence is a complex process that regulated by multiple signaling pathways, including nuclear factor erythroid 2-related factor (Nrf2)/ antioxidant response element (ARE) signaling pathway. Nrf2/ARE pathway as the central defense mechanism against oxidative stress controls the expression of many antioxidant and anti-inflammatory genes in the nucleus, and plays a crucial role in the treatment of IBD. Various studies have proved that many natural compounds target Nrf2/ARE signaling pathway to treat IBD. Here, we introduced the regulatory mechanism of the Nrf2/ARE pathway, and its role in IBD and IBD complications (intestinal fibrosis and colorectal cancer (CRC)); summarized the research progress of Nrf2 targeted natural compounds and extracts in the treatment of IBD; and finally described the intestinal microbiota that alleviate or treat IBD via activating Nrf2/ARE signaling pathway. This review highlights the potential for targeting Nrf2/ARE pathway to treat IBD.

Effect of green-lipped mussel (Perna canaliculus) supplementation on faecal microbiota, body composition and iron status markers in overweight and obese postmenopausal women: a randomised, double-blind, placebo-controlled trial

The present study aimed to determine the effect of whole meat GSM powder on gut microbiota abundance, body composition and iron status markers in healthy overweight or obese postmenopausal women. This was a 3-months trial involving forty-nine healthy postmenopausal women with body mass index (BMI) between 25 and 35 kg/m² who were randomly assigned to receive 3 g/d of either GSM powder (n 25) or placebo (n 24). The gut microbe abundance, serum iron status markers and body composition were measured at the baseline and the end of the study. The between-group comparison at the baseline showed a lower abundance of Bacteroides and Clostridium XIVa in the GSM group compared with the placebo (P = 0⋅04). At the baseline, the body fat (BF)% and gynoid fat% were higher in the GSM group compared with the placebo (P < 0⋅05). No significant changes were found in any of the outcome measures, except for ferritin levels that showed a significant reduction over time (time effect P = 0⋅01). Some trend was observed in bacteria including Bacteroides and Bifidobacterium which tended to increase in the GSM group while their abundance decreased or remained at their baseline level in the control group. Supplementation with GSM powder did not result in any significant changes in gut microbe abundance, body composition and iron markers compared with placebo. However, some commensal bacteria such as Bacteroides and Bifidobacteria tended to increase following supplementation with GSM powder. Overall, these findings can expand the knowledge surrounding the effects of whole GSM powder on these outcome measures in healthy postmenopausal women.

What happens to gut microorganisms and potential repair mechanisms when meet heavy metal(loid)s

Heavy metal (loid) pollution is a significant threat to human health, as the intake of heavy metal (loid)s can cause disturbances in intestinal microbial ecology and metabolic disorders, leading to intestinal and systemic diseases. Therefore, it is important to understand the effects of heavy metal (loid)s on intestinal microorganisms and the necessary approaches to restore them after damage. This review provides a summary of the effects of common toxic elements, such as lead (Pb), cadmium (Cd), chromium (Cr), and metalloid arsenic (As), on the microbial community and structure, metabolic pathways and metabolites, and intestinal morphology and structure. The effects of heavy metal (loid)s on metabolism are focused on energy, nitrogen, and short-chain fatty acid metabolism. We also discussed the main solutions for recovery of intestinal microorganisms from the effects of heavy metal (loid)s, namely the supplementation of probiotics, recombinant bacteria with metal resistance, and the non-toxic transformation of heavy metal (loid) ions by their own intestinal flora. This article provides insight into the toxic effects of heavy metals and As on gut microorganisms and hosts and provides additional therapeutic options to mitigate the damage caused by these toxic elements.

Bile acids and microbes in metabolic disease

Bile acids (BAs) serve as physiological detergents that enable the intestinal absorption and transportation of nutrients, lipids and vitamins. BAs are primarily produced by humans to catabolize cholesterol and play crucial roles in gut metabolism, microbiota habitat regulation and cell signaling. BA-activated nuclear receptors regulate the enterohepatic circulation of BAs which play a role in energy, lipid, glucose, and drug metabolism. The gut microbiota plays an essential role in the biotransformation of BAs and regulates BAs composition and metabolism. Therefore, altered gut microbial and BAs activity can affect human metabolism and thus result in the alteration of metabolic pathways and the occurrence of metabolic diseases/syndromes, such as diabetes mellitus, obesity/hypercholesterolemia, and cardiovascular diseases. BAs and their metabolites are used to treat altered gut microbiota and metabolic diseases. This review explores the increasing body of evidence that links alterations of gut microbial activity and BAs with the pathogenesis of metabolic diseases. Moreover, we summarize existing research on gut microbes and BAs in relation to intracellular pathways pertinent to metabolic disorders. Finally, we discuss how therapeutic interventions using BAs can facilitate microbiome functioning and ease metabolic diseases.

Multi-omics provide mechanistic insight into the Pb-induced changes in tadpole fitness-related traits and environmental water quality

Water pollution from lead/Pb²⁺ poses a significant threat to aquatic ecosystems, and its repercussions on aquatic animals have received considerable attention. Although Pb²⁺ has been found to affect numerous aspects of animals, including individual fitness, metabolic status, and symbiotic microbiota, few studies have focused on the associations between Pb²⁺-induced variations in fitness, metabolome, symbiotic microbiome, and environmental parameters in the same system, limiting a comprehensive understanding of ecotoxicological mechanisms from a holistic perspective. Moreover, most ecotoxicological studies neglected the potential contributions of anions to the consequences generated by inorganic lead compounds. We investigated the effects of Pb(NO₃)₂ at environmentally relevant concentrations on the Rana omeimontis tadpoles and the water quality around them, using blank and NaNO₃-treated groups as control. Results showed that Pb(NO₃)₂ not only induced a rise in water nitrite level, but exposure to this chemical also impaired tadpole fitness-related traits (e.g., growth and development). The impacts on tadpoles were most likely a combination of Pb²⁺ and NO₃^-. Tissue metabolomics revealed that Pb(NO₃)₂ exposure influenced animal substrate (i.e., carbohydrate, lipid, and amino acid) and prostaglandin metabolism. Pb(NO₃)₂ produced profound shifts in gut microbiota, with increased Proteobacteria impairing Firmicutes, resulting in higher aerobic and possibly pathogenic bacteria. NaNO₃ also influenced tadpole metabolome and gut microbiome, in a manner different to that of Pb(NO₃)₂. The presence of NO₃^- seemed to counteract some changes caused by Pb²⁺, particularly on the microbiota. Piecewise structural equation model and correlation analyses demonstrated connections between tissue metabolome and gut microbiome, and the variations in tadpole phenotypic traits and water quality were linked to changes in tissue metabolome and gut microbiome. These findings emphasized the important roles of gut microbiome in mediating the effects of toxin on aquatic ecosystem. Moreover, it is suggested to consider the influences of anions in the risk assessment of heavy metal pollutions.

Characterizing serum amino acids in schizophrenic patients: Correlations with gut microbes

Amino acid abnormalities have been suggested to be a key pathophysiological mechanism in schizophrenia (SZ). Recently, gut microbes were found to be critically involved in mental and metabolic diseases. However, the relationship between serum amino acid levels and gut microbes in SZ is rarely studied. Here, we analyzed serum amino acid levels in 76 untreated SZ patients and 79 healthy controls (HC). Serum levels of 10 amino acids were significantly altered in patients with SZ. We further classified the cut-off values for serum arginine, leucine, glutamine, and methionine levels to distinguish SZ patients from controls. These classifiers were shown to be effective in another validation cohort (49 SZ and 48 HC). The correlation between serum amino acids and clinical symptoms and cognitive functions was also analyzed. Arginine, leucine, glutamine, and methionine levels were significantly correlated with clinical symptoms and cognitive impairments in SZ patients. By metagenome shotgun sequencing of fecal samples, we found that patients with SZ with a low level of serum amino acids have higher richness and evenness of the gut microbiota. At the genus level, the abundances of Mitsuokella and Oscillibacter are significantly abnormal. At the mOTU level, 15 mOTUs in the low-level SZ group were significantly different from the HC group. In addition, Mitsuokella multacida was correlated with glutamine and methionine, respectively. Our research revealed that alterations in serum amino acid levels are critically related to changes in gut microbiota composition in SZ patients. These findings may shed light on new strategies for the diagnosis and treatment of SZ.

Structure similarity and molecular networking analysis for the discovery of polyphenol biotransformation products of gut microbes

Intestinal bacteria can metabolize polyphenols into highly bioavailable derivatives, which provide potential health-promoting effects to the host. However, the metabolic pathways and related products in this process are still largely unclear. Polyphenols are generally characterized by the presence of many phenolic structural units, which makes it possible to explore correlations among compounds based on similar molecular networks. In this study, we developed a standard-oriented/database-assisted molecular networking (SODA-MN) method for iterative compound annotation analysis to explore the metabolic profiles of polyphenol-rich black raspberry extract metabolized by representative gut bacteria. Starting from a group of polyphenol metabolites, the SODA-MN method predicted the possible polyphenol derivatives by adding or deducting common biotransformation groups and iterative annotating of structure similarity based on fragmentation spectra. Our results showed that 48 polyphenol derivatives in the first round of analysis alone (fragmentation match≥5, spec score >0.5) can be annotated, which were associated with 13 detected polyphenol standards that served as seed compounds. Meanwhile, this method was applied to a time-course study to show the time-dependent changes of polyphenols metabolized by a mix of gut bacteria. In addition, the metabolic capabilities of polyphenols among four representative gut bacteria were compared via our newly developed method and differential polyphenol metabolites were detected. In summary, the SODA-MN method provides a new approach for the annotation of unknown compounds by structure similarity and molecular networking analysis. Our analysis results could provide identification of key polyphenol derivatives that may contribute to the mechanistic investigations of their functions and assist our understanding of how polyphenols and gut bacteria interact to promote human health.

Consistent Alterations of Human Fecal Microbes After Transplantation into Germ-free Mice

Fecal microbiota transplantation (FMT) of human fecal samples into germ-free (GF) mice is useful for establishing causal relationships between the gut microbiota and human phenotypes. However, due to the intrinsic differences between human and mouse intestines and the different diets of the two organisms, it may not be possible to replicate human phenotypes in mice through FMT; similarly, treatments that are effective in mouse models may not be effective in humans. In this study, we aimed to identify human gut microbes that undergo significant and consistent changes (i.e., in relative abundances) after transplantation into GF mice in multiple experimental settings. We collected 16S rDNA-seq data from four published studies and analyzed the gut microbiota profiles from 1713 human-mouse pairs. Strikingly, on average, we found that only 47% of the human gut microbes could be re-established in mice at the species level, among which more than 1/3 underwent significant changes (referred to as "variable taxa"). Most of the human gut microbes that underwent significant changes were consistent across multiple human-mouse pairs and experimental settings. Consequently, about 1/3 of human samples changed their enterotypes, i.e., significant changes in their leading species after FMT. Mice fed with a controlled diet showed a lower enterotype change rate (23.5%) than those fed with a noncontrolled diet (49.0%), suggesting a possible solution for rescue. Most of the variable taxa have been reported to be implicated in human diseases, with some recognized as the causative species. Our results highlight the challenges of using a mouse model to replicate human gut microbiota-associated phenotypes, provide useful information for researchers using mice in gut microbiota studies, and call for additional validations after FMT. An online database named FMT-DB is publicly available at http://fmt2mice.humangut.info/#/.

Metagenomic analysis of gut microbiome reveals a dynamic change in Alistipes onderdonkii in the preclinical model of pancreatic cancer, suppressing its proliferation

Pancreatic cancer is a lethal cancer with aggressive and invasive characteristics. By the time it is diagnosed, patients already have tumors extended to other organs and show extremely low survival rates. The gut microbiome is known to be associated with many diseases and its imbalance affects the pathogenesis of pancreatic cancer. In this study, we established an orthotopic, patient-derived xenograft model to identify how the gut microbiome is linked to pancreatic ductal adenocarcinoma (PDAC). Using the 16S rDNA metagenomic sequencing, we revealed that the levels of Alistipes onderdonkii and Roseburia hominis decreased in the gut microbiome of the PDAC model. To explore the crosstalk between the two bacteria and PDAC cells, we collected the supernatant of the bacteria or cancer cell culture medium and treated it in a cross manner. While the cancer cell medium did not affect bacterial growth, we observed that the A. onderdonkii medium suppressed the growth of the pancreatic primary cancer cells. Using the bromodeoxyuridine/7-amino-actinomycin D (BrdU/7-AAD) staining assay, we confirmed that the A. onderdonkii medium inhibited the proliferation of the pancreatic primary cancer cells. Furthermore, RNA-seq analysis revealed that the A. onderdonkii medium induced unique transcriptomic alterations in the PDAC cells, compared to the normal pancreatic cells. Altogether, our data suggest that the reduction in the A. onderdonkii in the gut microbiome provides a proliferation advantage to the pancreatic cancer cells. KEY POINTS: • Metagenome analysis of pancreatic cancer model reveals A. onderdonkii downregulation. • A. onderdonkii culture supernatant suppressed the proliferation of pancreatic cancer cells. • RNA seq data reveals typical gene expression changes induced by A. onderdonkii.

Inter-trophic Interaction of Gut Microbiota in a Tripartite System

Gut microbiota can be transmitted either environmentally or socially and vertically at intraspecific level; however, whether gut microbiota interact along trophic levels has been largely overlooked. Here, we characterized the gut bacterial communities of weevil larvae of Curculio arakawai that infest acorns of Mongolian oak (Quercus mongolica) as well as acorn-eating mammals, Siberian chipmunk (Tamias sibiricus), to test whether consumption of seed-borne larvae remodels the gut bacterial communities of T. sibiricus. Ingestion of weevil larvae of C. arakawai significantly altered the gut bacterial communities of T. sibiricus. Consequently, T. sibiricus fed larvae of C. arakawai showed higher capability to counter the negative effects of tannins, in terms of body weight maintenance, acorn consumption, N content in feces, urine pH, and blood ALT activity. Our results may first show that seed-borne insects as hidden players have a potential to alter the gut microbiota of seed predators in the tripartite system.

Gut health: The results of microbial and mucosal immune interactions in pigs

There are a large number of microorganisms in the porcine intestinal tract. These microorganisms and their metabolites contribute to intestinal mucosal immunity, which is of great importance to the health of the host. The host immune system can regulate the distribution and composition of intestinal microorganisms and regulate the homeostasis of intestinal flora by secreting a variety of immune effector factors, such as mucin, secretory immunoglobulin A (sIgA), regenerating islet-derived III (RegIII)γ, and defensin. Conversely, intestinal microorganisms can also promote the differentiation of immune cells including regulatory T cells (T_reg) and Th17 cells through their specific components or metabolites. Studies have shown that imbalances in the intestinal flora can lead to bacterial translocation and compromised intestinal barrier function, affecting the health of the body. This review focuses on the composition of the pig intestinal flora and the characteristics of intestinal mucosal immunity, discusses the interaction mechanism between the flora and intestinal mucosal immunity, as well as the regulation through fecal microbiota transplantation (FMT), dietary nutritional composition, probiotics and prebiotics of pig intestinal microecology. Finally, this review provides insights into the relationship between intestinal microorganisms and the mucosal immune system.

Structural basis for the exolytic activity of polysaccharide lyase family 6 alginate lyase BcAlyPL6 from human gut microbe Bacteroides clarus

Alginate is the structural polysaccharide of the cell wall of brown algae, which is an important carbon source for marine life. The depolymerization of alginate is dependent on alginate lyases. Recent studies showed that the alginate utilization ability had been obtained by human gut microbes. In contrast to the great number of studies on alginate lyases from marine/soil organisms, studies on alginate lyases from gut microbes are still limited. Here, the structure of a polysaccharide lyase family 6 (PL6) alginate lyase from human gut microbe Bacteroides clarus was solved by X-ray crystallography, which represents the cluster of two-domain PL6 alginate lyases from Bacteroidetes. Similar with the two-domain alginate lyase AlyGC originated from marine bacterium, both the N terminal domain (NTD) and C terminal domain (CTD) of BcAlyPL6 show right-handed parallel β-helix fold. However, unlike AlyGC, which forms a homodimer, BcAlyPL6 functions as a monomer. Biochemical analysis indicates that the substrate binding affinity is mainly contributed by the NTD while the CTD of BcAlyPL6 is involved in the formation of -1 subsite, which is essential for substrate turnover rate. Furthermore, CTD is involved in shaping a closed catalytic pocket, and deletion of it leads to increased activity towards highly polymerized substrate. Structure comparison of PL6 family alginate lyases implies that the linkers of two-domain alginate lyases might have evolutionary relationship with the N/C terminal extension of single-domain lyases.

Nanocolloids in drinking water increase the risk of obesity in mice by modulating gut microbes

Both gut microbes and environmental contamination may cause metabolic disorders and obesity. However, the relationships among gut microbes, environmental contamination and obesity remain obscure. The drinking water on a national scale (31 cities in China) contained nanocolloid-pattern contamination at the mg/L level, a concentration that is 10- to 100-fold higher than commonly reported pollutants. Exposure to nanocolloids (environmentally related dose, 0.15 mg/kg) for three weeks increased the body weight and leptin levels of mice and decreased the expression of adiponectin. Nanocolloids increased the ratio of Firmicutes to Bacteroidetes, a typical obesity-related phenomenon, in the obese individuals. Oral administration of resveratrol verified the role of gut microbes in the tendency toward obesity induced by nanocolloids. The ratio of Firmicutes to Bacteroidetes is positively correlated with body weight and leptin levels. Compared to the control, the levels of triglycerides and high-density lipoprotein cholesterol were up- and downregulated by the tested nanocolloids at 0.15 mg/kg, respectively. Long-chain fatty acids, lipid metabolites and the expression of lipid synthesis-related genes (Fas, Srebp-1 and ACC-1) were also significantly increased by nanocolloids. The present study provides new insights that improve our understanding the risks of obesity associated with drinking water contamination that are mediated by gut microbes.

Enzyme functionalized microgels enable precise regulation of dissolved oxygen and anaerobe culture

Anaerobes are a major constituent of the gut microbiome and profoundly influence the overall health of humans. However, the lack of a simple, cost-effective, and scalable system that mimics the anaerobic conditions of the human gut is hindering research on the gut microbiome and the development of therapeutics. Here, we address this gap by using glucose oxidase and catalase containing gelatin microparticles (GOx-CAT-GMPs) to precisely regulate dissolved oxygen concentration [O2] via GOx-mediated consumption of oxygen. Fluorescence images generated using conjugated polymer afterglow nanoparticles showed that [O2] can be tuned from 257.9 ​± ​6.2 to 0.0 ​± ​4.0 ​μM using GOx-CAT-GMPs. Moreover, when the obligate anaerobe Bacteroides thetaiotaomicron was inoculated in media containing GOx-CAT-GMPs, bacterial growth under ambient oxygen was comparable to control conditions in an anaerobic chamber (5.4 ​× ​105 and 8.8 ​× ​105 colony forming units mL-1, respectively). Finally, incorporating GOx-CAT-GMPs into a bioreactor that permitted continuous radial diffusion of oxygen and glucose generated a gut-mimetic [O2] gradient of 132.4 ​± ​2.6 ​μM in the outer ring of the reactor to 7.9 ​± ​1.7 ​μM at the core. Collectively, these results indicate that GOx-CAT-GMPs are highly effective oxygen-regulating materials. These materials can potentially be leveraged to advance gut microbiome research and fecal microbiota transplantation, particularly in low-resource settings.

Dietary fiber and microbiota interaction regulates sow metabolism and reproductive performance

Dietary fiber is a critical nutrient in sow diet and has attracted interest of animal nutritionists for many years. In addition to increase sows’ satiety, dietary fiber has been found to involve in the regulation of multiple biological functions in the sow production. The interaction of dietary fiber and gut microbes can produce bioactive metabolites, which are of great significance to sows' metabolism and reproductive performance. This article reviewed the interaction between dietary fiber and gut microbes in regulating sows' gut microbial diversity, intestinal immune system, lactation, and production performance, with the aim to provide a new strategy for the use of dietary fiber in sow diets.

Arsenic transformation mediated by gut microbiota affects the fecundity of Caenorhabditis elegans

Arsenic biotransformation has been discovered in guts of soil invertebrates. Reproduction of invertebrates is sensitive to arsenic contamination in soils. However, little is known about the impact of gut microbe-mediated arsenic biotransformation on the fecundity of invertebrates. Here, Caenorhabditis elegans was firstly pre-fed with Escherichia coli BL21 possessing the capability of reducing arsenate [As(V)] or BL21M having the ability to reduce As(V) and methylate arsenite [As(III)], then inoculated worms were transferred to inactive E. coli AW3110 (harboring no arsenic transformation gene)-seeded plates treated with As(V) at different concentrations. Quantification of gut microbes showed that both E. coli BL21 and BL21M stably colonized in the guts after worms were cultured on inactive E. coli AW3110-seeded plates for 72 h. The analysis of arsenic species indicated that there was As(III) in C. elegans guts colonized with E. coli BL21, As(III) and dimethylarsinic acid [DMAs(V)] in C. elegans guts with E. coli BL21M exposed to As(V) for 6 h. After treatment of 100 μM As(V), decrease in brood sizes was observed for worms that were colonized with E. coli BL21 or BL21M compared to that with AW3110 in the guts. The levels of vitellogenin (VTG), glutathione S-transferases (GST) and superoxide dismutase (SOD), closely linked to reproduction and antioxidation-linked indicators, were the highest in worms whose guts colonized with E. coli BL21, followed by worms colonized with E. coli BL21M and worms colonized with inactive E. coli AW3110 exposed to As(V). Our results indicated the toxic impact of As(III) and DMAs(V) produced by gut microbes on reproduction of C. elegans. The work provides novel insight into the interplay between arsenic biotransformation mediated by gut microbes and the host fecundity in soils.

Role of gut-liver axis dysfunction in pathogenesis of non-alcoholic fatty liver disease: Implications for treatment strategies

Non-alcoholic fatty liver disease (NAFLD) is a chronic metabolic disease whose pathogenesis is not fully understood and involves multiple factors. Metabolic disorder caused by gut microbial imbalance is a key factor contributing to the development of NAFLD. Several studies show that gut barrier dysfunction will cause the occurrence of toxic metabolites in blood and bacterial translocation. The "dialogue" between the gut and the liver highlights the key role of the gut-liver axis in the process of NAFLD. This paper will summarize the relationship between the gut-liver axis and the pathogenesis of NAFLD, as well as its implications for the treatment of NAFLD.

Role of intestinal microorganisms in brain-gut axis and related diseases

There is a bidirectional communication system between the gut and brain, which is called the brain-gut axis. The influence of gut flora is not only limited to the gut but also expanded to the whole body including the cardiovascular system and metabolism via inflammation and immune reaction. On the other hand, the brain and gut influence each other, and the central system has an impact on the digestive system via the brain-gut axis. In this paper, we discuss the mechanism of interactions between the brain-gut axis and gut microbes, with an aim to provide ideas and clues for the treatment of related diseases.

Prevalence and genetic diversity of Blastocystis in family units living in the United States

The human gut is host to a diversity of microorganisms including the single-celled microbial eukaryote Blastocystis. Although Blastocystis has a global distribution, there is dearth of information relating to its prevalence and diversity in many human populations. The mode of Blastocystis transmission to humans is also insufficiently characterised, however, it is speculated to vary between different populations. Here we investigated the incidence and genetic diversity of Blastocystis in a US population and also the possibility of Blastocystis human-human transmission between healthy individuals using family units (N=50) living in Boulder, Colorado as our sample-set. Ten of the 139 (~7%) individuals in our dataset were positive for Blastocystis, nine of whom were adults and one individual belonging to the children/adolescents group. All positive cases were present in different family units. A number of different Blastocystis subtypes (species) were detected with no evidence of mixed infections. The prevalence of Blastocystis in this subset of the US population is comparatively low relative to other industrialised populations investigated to date; however, subtype diversity was largely consistent with that previously reported in studies of European populations. The distribution of Blastocystis within family units indicates that human-human transmission is unlikely to have occurred within families that participated in this study. It is not unexpected that given the world-wide variation in human living conditions and lifestyles between different populations, both the prevalence of Blastocystis and its mode of transmission to humans may vary considerably.

Diversity and composition of the bacterial community in Amphioxus feces

Amphioxus is a typical filter feeder animal and is confronted with a complex bacterial community in the seawater of its habitat. It has evolved a strong innate immune system to cope with the external bacterial stimulation, however, the ecological system of the bacterial community in Amphioxus remains unknown. Through massive parallel 16S rRNA gene tag pyrosequencing, the investigation indicated that the composition of wild and lab-cultured Amphioxus fecal bacteria was complex with more than 85,000 sequence tags being assigned to 12/13 phyla. The bacterial diversity between the two fecal samples was similar according to OTU richness of V4 tag, Chao1 index, Shannon index and Rarefaction curves, however, the most prominent bacteria in wild feces were genera Pseudoalteromonas (gamma Proteobacteria) and Arcobacter (epsilon Proteobacteria); the highly abundant bacteria in lab-cultured feces were other groups, including Leisingera, Phaeobacter (alpha Proteobacteria), and Vibrio (gamma Proteobacteria). Such difference indicates the complex fecal bacteria with the potential for multi-stability. The bacteria of habitat with 28 assigned phyla had the higher bacterial diversity and species richness than both fecal bacteria. Shared bacteria between wild feces and its habitat reached to approximately 90% (153/169 genera) and 28% (153/548 genera), respectively. As speculative, the less diversity of both fecal bacteria compared to its habitat partly because Amphioxus lives buried and the feces will ultimately end up in the sediment. Therefore, our study comprehensively investigates the complex bacterial community of Amphioxus and provides evidence for understanding the relationship of this basal chordate with the environment.