Deciphering the Chemical Lexicon of Host-Gut Microbiota Interactions

Impact of imidacloprid exposure on gestational hyperglycemia: A multi-omics analysis

Imidacloprid (IMI), a commonly utilized neonicotinoid insecticide, has been identified to adversely impact glucose homeostasis. Pregnant women are believed to be more sensitive to toxins than non-pregnant women, and the impact of IMI exposure on gestational hyperglycemia remain unclear. To explore the impact, pregnant mice fed a high-fat diet were exposed to different doses (0.06, 0.6, 6 mg/kg bw/day) of IMI by gavage. Glucose homeostasis-related parameters were measured. The glucose homeostasis influenced by IMI treatment was explored through integrating gut microbiota, metabolomic and transcriptomic analysis. Results showed that IMI-H (6 mg/kg bw/day) exposure notably restricted gestational weight gain and perturbed glucose homeostasis characterized by reduced glucose tolerance and insulin sensitivity, alongside elevated levels of fasting blood glucose and insulin. Multi-omics analysis revealed that IMI-H exposure induced significant changes in the richness and composition of the gut microbiome. The metabolite profiles of serum samples and cecal contents, and transcriptome of liver and ileum were all affected by IMI-H treatment. The altered gut microbiota, metabolites and genes exhibited significant correlations with glucose homeostasis-related parameters. These differential metabolites and genes were implicated in various metabolic pathways including bile secretion, glucagon signaling pathway, lipid metabolism, fatty acid metabolism. Significant correlations were observed between the altered gut microbiota and caecum metabolome as well as liver transcriptome. For example, the abundance of Oscillibacter was strongly correlated with gut microflora-related metabolites (Icosenoic acid, Lysosulfatide, and fluticasone) and liver differential genes (Grin3b, Lifr, and Spta1). Together, IMI exposure resulted in significant changes in microbial composition, along with alterations in certain metabolites and genes associated with metabolic process, which may promote gestational hyperglycemia.

Jianpi Jiedu decoction suppresses colorectal cancer growth by inhibiting M2 polarization of TAMs through the tryptophan metabolism-AhR pathway

BACKGROUND

Traditional Chinese medicine, JianpiJiedu decoction (JPJDF), has been utilized in colorectal cancer (CRC) treatment for over forty years. The potential of JPJDF to inhibit CRC through modulation of intestinal microbiota and their metabolites remains uncertain.

AIMS

This study aims to further investigate the therapeutic mechanisms of JPJDF in CRC.

METHODS

CAC mouse models were developed using azoxymethane (AOM) and dextran sulfate sodium (DSS). Intestinal tissues and contents underwent 16S rRNA gene sequencing and untargeted metabolomics analysis. Serum levels of IL-1β and TNF-α were measured using ELISA. Immunohistochemistry was utilized to assess the expression of Ki67, ZO-1, Occludin, CD68, and CD206. Furthermore, western blotting was performed to evaluate the protein expression of AhR and NF-κB.

RESULTS

JPJDF inhibited colorectal tumourigenesis in AOM/DSS treated mice, while also suppressing tumor cell proliferation and upregulating the expression of tight junction proteins. The results of 16S rRNA gene sequencing analysis revealed that JPJDF altered intestinal microbiota composition by increasing the abundance of beneficial bacteria. Additionally, JPJDF reduced tryptophan metabolites, effectively alleviating inflammation and significantly restoring intestinal barrier function in CAC mice. Molecular biology experiments confirmed that JPJDF suppressed the expression levels of AhR and M2-type tumor-associated macrophages, thereby promoting anti-tumor immunity and exerting inhibitory effects on CAC growth.

CONCLUSION

JPJDF can regulate the tryptophan metabolism-AhR pathway by modulating the gut microbiota, reducing intestinal inflammation, improving intestinal barrier function, enhancing anti-tumor immunity, and effectively inhibiting CAC growth.

Gut Microbiota Metabolite Messengers in Brain Function and Pathology at a View of Cell Type-Based Receptor and Enzyme Reaction

The human gastrointestinal (GI) tract houses a diverse microbial community, known as the gut microbiome comprising bacteria, viruses, fungi, and protozoa. The gut microbiome plays a crucial role in maintaining the body's equilibrium and has recently been discovered to influence the functioning of the central nervous system (CNS). The communication between the nervous system and the GI tract occurs through a two-way network called the gut-brain axis. The nervous system and the GI tract can modulate each other through activated neuronal cells, the immune system, and metabolites produced by the gut microbiome. Extensive research both in preclinical and clinical realms, has highlighted the complex relationship between the gut and diseases associated with the CNS, such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis. This review aims to delineate receptor and target enzymes linked with gut microbiota metabolites and explore their specific roles within the brain, particularly their impact on CNS-related diseases.

Cinnamic Acid, Perillic Acid, and Tryptophan Metabolites Differentially Regulate Ion Transport and Serotonin Metabolism and Signaling in the Mouse Ileum In Vitro

Phytochemicals and tryptophan (Trp) metabolites have been found to modulate gut function and health. However, whether these metabolites modulate gut ion transport and serotonin (5-HT) metabolism and signaling requires further investigation. The aim of this study was to investigate the effects of selected phytochemicals and Trp metabolites on the ion transport and 5-HT metabolism and signaling in the ileum of mice in vitro using the Ussing chamber technique. During the in vitro incubation, vanillylmandelic acid (VMA) reduced (p < 0.05) the short-circuit current, and 100 μM chlorogenic acid (CGA) (p = 0.12) and perillic acid (PA) (p = 0.14) had a tendency to reduce the short-circuit current of the ileum. Compared with the control, PA and N-acetylserotonin treatment upregulated the expression of tryptophan hydroxylase 1 (Tph1), while 100 μM cinnamic acid, indolelactic acid (ILA), and 10 μM CGA or indoleacetaldehyde (IAld) treatments downregulated (p < 0.05) the mRNA levels of Tph1. In addition, 10 μM IAld or 100 μM ILA upregulated (p < 0.05) the expression of monoamine oxidase A (Maoa). However, 10 μM CGA or 100 μM PA downregulated (p < 0.05) Maoa expression. All selected phytochemicals and Trp metabolites upregulated (p < 0.05) the expression of Htr4 and Htr7 compared to that of the control group. VMA and CGA reduced (p < 0.05) the ratios of Htr1a/Htr7 and Htr4/Htr7. These findings may help to elucidate the effects of phytochemicals and Trp metabolites on the regulation of gut ion transport and 5-HT signaling-related gut homeostasis in health and disease.

Effects of fermented sweet potato residue on nutrient digestibility, meat quality, and intestinal microbes in broilers

This study aimed to investigate the effects of different proportions of dietary fermented sweet potato residue (FSPR) supplementation as a substitute for corn on the nutrient digestibility, meat quality, and intestinal microbes of yellow-feathered broilers. Experiment 1 (force-feeding) evaluated the nutrient composition and digestibility of mixtures with different proportions of sweet potato residue (70%, 80%, 90%, and 100%) before and after fermentation. In Experiment 2 (metabolic growth), a total of 420 one-day-old yellow-feathered broilers were randomly allocated to 4 groups and fed corn-soybean meal-based diets with 0, 5%, 8%, and 10% FSPR as a substitute for corn. The force-feeding and metabolic growth experiments were performed for 9 and 70 d, respectively. The treatment of 70% sweet potato residue (after fermentation) had the highest levels of crude protein, ether extract, and crude fiber and improved the digestibility of crude protein and amino acids (P < 0.05). Although dietary FSPR supplementation at different levels had no significant effect on growth performance and intestinal morphology, it improved slaughter rate, half-chamber rate, full clearance rate, and meat color, as well as reduced cooking loss in the breast and thigh muscles (P < 0.05). Dietary supplementation with 8% and 10% FSPR increased the serum immunoglobulin M and immunoglobulin G levels in broilers (P < 0.05). Furthermore, 10% FSPR increased the Shannon index and Ruminococcaceae_UCG-014, Ruminococcaceae_UCG-010 and Romboutsia abundances and decreased Sutterella and Megamonas abundances (P < 0.05). Spearman's correlation analysis showed that meat color was positively correlated with Ruminococcaceae_UCG-014 (P < 0.05) and negatively correlated with Megamonas (P < 0.05). Collectively, 70% sweet potato residue (after fermentation) had the best nutritional value and nutrient digestibility. Dietary supplementation with 8% to 10% FSPR as a substitute for corn can improve the slaughter performance, meat quality, and intestinal microbe profiles of broilers. Our findings suggest that FSPR has the potential to be used as a substitute for corn-soybean meals to improve the meat quality and intestinal health of broilers.

Genetically determined gut microbiota associates with pulmonary arterial hypertension: a Mendelian randomization study

BACKGROUND

Emerging evidences have demonstrated that gut microbiota composition is associated with pulmonary arterial hypertension (PAH). However, the underlying causality between intestinal dysbiosis and PAH remains unresolved.

METHOD

An analysis using the two-sample Mendelian randomization (MR) approach was conducted to examine the potential causal relationship between gut microbiota and PAH. To assess exposure data, genetic variants associated with 196 bacterial traits were extracted from the MiBioGen consortium, which included a sample size of 18,340 individuals. As for the outcomes, summary statistics for PAH were obtained from the NHGRI-EBI GWAS Catalog, which conducted a meta-analysis of four independent studies comprising a total of 11,744 samples. Causal effects were estimated employing various methods, including inverse variance weighted (IVW), MR-Egger, weighted median, weight mode and simple mode, with sensitivity analyses also being implemented with Cochran's Q test, MR-Egger intercept test, MR-PRESSO, leave-one-out analysis, and funnel plots.

RESULTS

Following false discovery rate (FDR) correction, the genetically predicted genus Eubacterium fissicatena group (odds ratio (OR) 1.471, 95% confidence interval (CI) 1.178-1.837, q = 0.076) exhibited a causal association with PAH. In addition, the genus LachnospiraceaeUCG004 (OR 1.511, 95% CI 1.048-2.177) and genus RuminococcaceaeUCG002 (OR 1.407, 95% CI 1.040-1.905) showed a suggestive increased risk of PAH, while genus Eubacterium eligens group (OR 0.563, 95% CI 0.344-0.922), genus Phascolarctobacterium (OR 0.692, 95% CI 0.487-0.982), genus Erysipelatoclostridium (OR 0.757, 95% CI 0.579-0.989) and genus T-yzzerella3 (OR 0.768, 95% CI 0.624-0.945) were found to have nominal protective effect against PAH.

CONCLUSION

The findings from our MR study have revealed a potential causal relationship between gut microbiota and PAH. Specifically, we have identified four types of gut microbiota that exhibit a protective effect on PAH, as well as three types that have a detrimental impact on PAH, thereby offering valuable insights for future mechanistic and clinical investigations in the field of PAH.

Tryptophan Metabolism in Alzheimer's Disease with the Involvement of Microglia and Astrocyte Crosstalk and Gut-Brain Axis

Alzheimer's disease (AD) is an age-dependent neurodegenerative disease characterized by extracellular Amyloid Aβ peptide (Aβ) deposition and intracellular Tau protein aggregation. Glia, especially microglia and astrocytes are core participants during the progression of AD and these cells are the mediators of Aβ clearance and degradation. The microbiota-gut-brain axis (MGBA) is a complex interactive network between the gut and brain involved in neurodegeneration. MGBA affects the function of glia in the central nervous system (CNS), and microbial metabolites regulate the communication between astrocytes and microglia; however, whether such communication is part of AD pathophysiology remains unknown. One of the potential links in bilateral gut-brain communication is tryptophan (Trp) metabolism. The microbiota-originated Trp and its metabolites enter the CNS to control microglial activation, and the activated microglia subsequently affect astrocyte functions. The present review highlights the role of MGBA in AD pathology, especially the roles of Trp per se and its metabolism as a part of the gut microbiota and brain communications. We (i) discuss the roles of Trp derivatives in microglia-astrocyte crosstalk from a bioinformatics perspective, (ii) describe the role of glia polarization in the microglia-astrocyte crosstalk and AD pathology, and (iii) summarize the potential of Trp metabolism as a therapeutic target. Finally, we review the role of Trp in AD from the perspective of the gut-brain axis and microglia, as well as astrocyte crosstalk, to inspire the discovery of novel AD therapeutics.

Identification of avaC from Human Gut Microbial Isolates that Converts 5AVA to 2-Piperidone

2-piperidone is a crucial industrial raw material of high-value nylon-5 and nylon-6,5. Currently, a major bottleneck in the biosynthesis of 2-piperidone is the identification of highly efficient 2-piperidone synthases. In this study, we aimed to identify specific strains among 51 human gut bacterial strains capable of producing 2-piperidone and to elucidate its synthetic mechanism. Our findings revealed that four gut bacterial strains, namely Collinsella aerofaciens LFYP39, Collinsella intestinalis LFYP54, Clostridium bolteae LFYP116, and Clostridium hathewayi LFYP18, could produce 2-piperidone from 5-aminovaleric acid (5AVA). Additionally, we observed that 2-piperidone could be synthesized from proline through cross-feeding between Clostridium difficile LFYP43 and one of the four 2-piperidone producing strains, respectively. To identify the enzyme responsible for catalyzing the conversion of 5AVA to 2-piperidone, we utilized a gain-of-function library and identified avaC (5-aminovaleric acid cyclase) in C. intestinalis LFYP54. Moreover, homologous genes of avaC were validated in the other three bacterial strains. Notably, avaC were found to be widely distributed among environmental bacteria. Overall, our research delineated the gut bacterial strains and genes involved in 2-piperidone production, holding promise for enhancing the efficiency of industrial biosynthesis of this compound.

Microbial and metabolomic profiles of type 1 diabetes with depression: A case-control study

BACKGROUND

Depression is the most common psychological disorder in patients with type 1 diabetes (T1D). However, the characteristics of microbiota and metabolites in these patients remain unclear. This study aimed to investigate microbial and metabolomic profiles and identify novel biomarkers for T1D with depression.

METHODS

A case-control study was conducted in a total of 37 T1D patients with depression (TD+), 35 T1D patients without depression (TD-), and 29 healthy controls (HCs). 16S rRNA gene sequencing and liquid chromatography-mass spectrometry (LC-MS) metabolomics analysis were conducted to investigate the characteristics of microbiota and metabolites. The association between altered microbiota and metabolites was explored by Spearman's rank correlation and visualized by a heatmap. The microbial signatures to discriminate TD+ from TD- were identified by a random forest (RF) classifying model.

RESULTS

In microbiota, 15 genera enriched in TD- and 2 genera enriched in TD+, and in metabolites, 14 differential metabolites (11 upregulated and 3 downregulated) in TD+ versus TD- were identified. Additionally, 5 genera (including Phascolarctobacterium, Butyricimonas, and Alistipes from altered microbiota) demonstrated good diagnostic power (area under the curve [AUC] = 0.73; 95% CI, 0.58-0.87). In the correlation analysis, Butyricimonas was negatively correlated with glutaric acid (r = -0.28, p = 0.015) and malondialdehyde (r = -0.30, p = 0.012). Both Phascolarctobacterium (r = 0.27, p = 0.022) and Alistipes (r = 0.31, p = 0.009) were positively correlated with allopregnanolone.

CONCLUSIONS

T1D patients with depression were characterized by unique profiles of gut microbiota and serum metabolites. Phascolarctobacterium, Butyricimonas, and Alistipes could predict the risk of T1D with depression. These findings provide further evidence that the microbiota-gut-brain axis is involved in T1D with depression.

Bifidobacterium mediate gut microbiota-remedied intestinal barrier damage caused by cyproconazole in zebrafish (Danio rerio)

The widespread use of cyproconazole (CPZ) enhances food security but may pose potential risks to non-target organisms. Therefore, we applied Multi-omics techniques to reveal the response of the intestinal barrier to CPZ exposure and explore whether the Bifidobacterium intervention experiment can repair the damage. First, we found that exposure to CPZ at environmentally relevant concentrations led to intestinal injury phenotype, significantly down-regulated intestinal protein gene expression, and up-regulated pro-inflammatory gene expression, further causing intestinal dysbacteriosis and metabolic disorders. In particular, by combining analysis of gut microbiota and metabolites, we noticed acetate, a key metabolite, which decreased sharply after exposure to high concentration of CPZ. Expectedly, after supplementing with Bifidobacterium (a core bacterium that produces acetate), we noticed that the acetate content was quickly restored. Further, we also verified that the increase in acetate content after Bifidobacterium supplementation at least partially promoted IL-22 secretion, which in turn stimulated the secretion of β-defensins (zfbd-1, zfbd-2, zfbd-3), thereby repairing the intestinal damage. In conclusion, our work confirms the potential of Bifidobacterium to improve intestinal damage and metabolic dysbiosis caused by CPZ exposure. It provides directional recommendations for the application of probiotics to repair the toxicological risk of pesticide exposure.

Dubosiella newyorkensis modulates immune tolerance in colitis via the L-lysine-activated AhR-IDO1-Kyn pathway

Commensal bacteria generate immensely diverse active metabolites to maintain gut homeostasis, however their fundamental role in establishing an immunotolerogenic microenvironment in the intestinal tract remains obscure. Here, we demonstrate that an understudied murine commensal bacterium, Dubosiella newyorkensis, and its human homologue Clostridium innocuum, have a probiotic immunomodulatory effect on dextran sulfate sodium-induced colitis using conventional, antibiotic-treated and germ-free mouse models. We identify an important role for the D. newyorkensis in rebalancing Treg/Th17 responses and ameliorating mucosal barrier injury by producing short-chain fatty acids, especially propionate and L-Lysine (Lys). We further show that Lys induces the immune tolerance ability of dendritic cells (DCs) by enhancing Trp catabolism towards the kynurenine (Kyn) pathway through activation of the metabolic enzyme indoleamine-2,3-dioxygenase 1 (IDO1) in an aryl hydrocarbon receptor (AhR)-dependent manner. This study identifies a previously unrecognized metabolic communication by which Lys-producing commensal bacteria exert their immunoregulatory capacity to establish a Treg-mediated immunosuppressive microenvironment by activating AhR-IDO1-Kyn metabolic circuitry in DCs. This metabolic circuit represents a potential therapeutic target for the treatment of inflammatory bowel diseases.

Mood and microbes: a comprehensive review of intestinal microbiota's impact on depression

Depression is considered a multifaceted and intricate mental disorder of growing concern due to its significant impact on global health issues. The human gut microbiota, also known as the "second brain," has an important role in the CNS by regulating it through chemical, immunological, hormonal, and neurological processes. Various studies have found a significant bidirectional link between the brain and the gut, emphasizing the onset of depression therapies. The biological and molecular processes underlying depression and microbiota are required, as the bidirectional association may represent a novel study. However, profound insights into the stratification and diversity of the gut microbiota are still uncommon. This article investigates the emerging evidence of a bacterial relationship between the gut and the brain's neurological system and its potential pathogenicity and relevance. The interplay of microbiota, immune system, nervous system neurotransmitter synthesis, and neuroplasticity transitions is also widely studied. The consequences of stress, dietary fibers, probiotics, prebiotics, and antibiotics on the GB axis are being studied. Multiple studies revealed the processes underlying this axis and led to the development of effective microbiota-based drugs for both prevention and treatment. Therefore, the results support the hypothesis that gut microbiota influences depression and provide a promising area of research for an improved knowledge of the etiology of the disease and future therapies.

Human Amniotic Membrane-Derived Mesenchymal Stem Cells Prevent Acute Graft-Versus-Host Disease in an Intestinal Microbiome-Dependent Manner

Acute graft-versus-host disease (aGVHD) represents a fatal severe complication after allogeneic hematopoietic stem cell transplantation. As a promising cell therapeutic strategy of aGVHD, the mechanism of mesenchymal stem cells (MSC) to ameliorate aGVHD has not been fully clarified, especially in the field of intestinal homeostasis including the intestinal microbiome involved in the pathogenesis of aGVHD. The present study aimed to explore the effect of MSC on intestinal homeostasis including the intestinal barrier and intestinal microbiome and its metabolites, as well as the role of intestinal microbiome in the preventive process of hAMSCs ameliorating aGVHD. The preventive effects of human amniotic membrane-derived MSC (hAMSCs) was assessed in humanized aGVHD mouse models. Immunohistochemistry and RT-qPCR were used to evaluate intestinal barrier function. The 16S rRNA sequencing and targeted metabolomics assay were performed to observe the alternation of intestinal microbiome and the amounts of medium-chain fatty acids (MCFAs) and short-chain fatty acids (SCFAs), respectively. Flow cytometry was performed to analyze the frequencies of T immune cells. Through animal experiments, we found that hAMSCs had the potential to prevent aGVHD. HAMSCs could repair the damage of intestinal barrier structure and function, as well as improve the dysbiosis of intestinal microbiome induced by aGVHD, and meanwhile, upregulate the concentration of metabolites SCFAs, so as to reshape intestinal homeostasis. Gut microbiota depletion and fecal microbial transplantation confirmed the involvement of intestinal microbiome in the preventive process of hAMSCs on aGVHD. Our findings showed that hAMSCs prevented aGVHD in an intestinal microbiome-dependent manner, which might shed light on a new mechanism of hAMSCs inhibiting aGVHD and promote the development of new prophylaxis regimes for aGVHD prevention.

Flunitrazepam and its metabolites compromise zebrafish nervous system functionality: An integrated microbiome, metabolome, and genomic analysis

The psychotropic drug flunitrazepam (FLZ) is frequently detected in aquatic environments, yet its neurotoxicity to aquatic organisms has not received sufficient attention. In this study, microbiome, metabolome, and genome analyses were conducted to study the effects of FLZ and its metabolite 7-aminoflunitrazepam (7-FLZ) on the zebrafish nervous system and understand their toxic mechanisms. The results demonstrated that drug exposure induced gut dysbiosis, decreased short-chain fatty acids and promoted the production of lipopolysaccharides (LPS). LPS entered the brain and interacted with Toll-like receptors to cause neuroinflammation by upregulating the expression of proinflammatory cytokines TNFα and NF-κB. The increased ratio of S-adenosylmethionine to S-adenosylhomocysteine in brain tissues indicated abnormal expression of Dnmt1 gene. Whole-genome bisulfite sequencing displayed an increase in differentially methylated regions (DMRs) associated-genes and pertinent biological pathways encompassed the MAPK signaling pathway, calcium signaling pathway, and Wnt signaling pathway. Correlation analysis confirmed connections between gut microbiota, their metabolites, inflammatory factors, and DNA methylation-related markers in brain tissue. These findings indicate that while the toxicity is somewhat reduced in metabolized products, both FLZ and 7-FLZ can induce DNA methylation in brain tissue and ultimately affect the biological function of the nervous system by disrupting gut microbiota and their metabolites.

Polystyrene nanoparticles induced mammalian intestine damage caused by blockage of BNIP3/NIX-mediated mitophagy and gut microbiota alteration

Nanoplastics possess the capacity for cellular internalization, and consequentially disrupt mitochondrial functionality, precipitating aberrations in energy metabolism. Given this, the potential accumulation of nanoplastics in alimentary sources presents a considerable hazard to the mammalian gastrointestinal system. While mitophagy serves as a cytoprotective mechanism that sustains redox homeostasis through the targeted removal of compromised mitochondria, the regulatory implications of mitophagy in nanoplastic-induced toxicity remain an underexplored domain. In the present investigation, polystyrene (PS) nanoparticles, with a diameter of 80 nm employed as a representative model to assess their toxicological impact and propensity to instigate mitophagy in intestinal cells both in vitro and in vivo. Data indicated that PS nanoparticles elicited BNIP3/NIX-mediated mitophagy within the intestinal milieu. Strikingly, the impediment of this degradation process at elevated concentrations was correlated with exacerbated pathological ramifications. In vitro assays corroborated that high-dosage cellular uptake of PS nanoparticles obstructed the mitophagy pathway. Furthermore, treatment with PS nanoparticles engendered alterations in gut microbiota composition and manifested a proclivity to modulate nutritional metabolism. Collectively, these findings elucidate that oral exposure to PS nanoparticles culminates in the inhibition of mitophagy and induces perturbations in the intestinal microbiota. This contributes valuable insights into the toxicological repercussions of nanoplastics on mammalian gastrointestinal health.

Stress in the microbiome-immune crosstalk

The gut microbiota exerts a mutualistic interaction with the host in a fragile ecosystem and the host intestinal, neural, and immune cells. Perturbations of the gastrointestinal track composition after stress have profound consequences on the central nervous system and the immune system. Reciprocally, brain signals after stress affect the gut microbiota highlighting the bidirectional communication between the brain and the gut. Here, we focus on the potential role of inflammation in mediating stress-induced gut-brain changes and discuss the impact of several immune cells and inflammatory molecules of the gut-brain dialogue after stress. Understanding the impact of microbial changes on the immune system after stress might provide new avenues for therapy.

Probiotic-Fermented Distillers Grain Alters the Rumen Microbiome, Metabolome, and Enzyme Activity, Enhancing the Immune Status of Finishing Cattle

A total of 30 Simmental crossbred cattle (6.50 months old, 265.0 ± 22.48 kg) were randomly divided into three groups, with 10 heads per group, and fed for 45 days. The diet treatments consisted of the Control group without PFDG supplementation, the PFDG-15% group with 15% PFDG substituting for 15% concentrate, and PFDG-30% group with 30% PFDG substituting for 30% concentrate. The results showed that compared with the Control group, the average daily gain (ADG) of the cattle in the PFDG-30% group decreased significantly (0.890 vs. 0.768 kg/d, p = 0.005). The serum malondialdehyde content of cattle in the PFDG-15% and PFDG-30% groups decreased significantly (p = 0.047) compared to that of the Control group. However, the serum superoxide dismutase activity of cattle in the PFDG-30% group was significantly higher than that of the Control group (p = 0.047). Meanwhile, both the PFDG-15% and PFDG-30% groups (1758.47 vs. 2061.30 μg/mL) showed higher serum levels of immunoglobulin G, while the interleukin-10 concentration was lower in the PFDG-30% group (p = 0.027). In addition, the PFDG-15% and PFDG-30% groups shifted the rumen microbiota by improving the abundances of F082 (related to propionic acid production) and fiber-degrading bacteria (Lachnospiraceae_UGG-009 and Prevotellaceae_UCG-001) and reducing the abundance of the disease-associated bacteria Selenomonas. A Kyoto encyclopedia of genes and genomes (KEGG) analysis illustrated that three key metabolic pathways, including phenylalanine metabolism, pyrimidine metabolism, and tryptophan metabolism, were enriched in the PFDG-15% group, but eight key metabolic pathways, including arachidonic acid metabolism, were enriched in the PFDG-30% group. Importantly, both the PFDG-15% and PFDG-30% groups increased (p < 0.01) the activities of cellulase, lipase, and protease in the rumen. Finally, the different bacterial abundance in the rumen was associated with changes in the ADG, serum antioxidant capacity, immune status, rumen enzyme activity, and metabolites. These results suggest that PFDG alters rumen microbiome abundance, metabolome, and enzyme activity for enhancing serum antioxidant capacity and the immune status, but when the supplemental level reaches 30%, it has a negative effect on ADG and the anti-inflammatory factors in finishing cattle.

Microbiota: A key factor affecting and regulating the efficacy of immunotherapy

BACKGROUND

Immunotherapy has made significant progress in cancer treatment; however, the responsiveness to immunotherapy varies widely among patients. Growing evidence has demonstrated the role of the gut microbiota in the efficacy of immunotherapy.

MAIN BODY

Herein, we summarise the changes in the microbiota in different cancers under various immunotherapies. The microbial-host signal transmission on immunotherapeutic responses and mechanisms associated with microbial translocation to tumours in the context of immunotherapy are also discussed. In addition, we have highlighted the clinical application value of methods for regulating the microbiota. Finally, we elaborate on the relationship between the microbiota, host and immunotherapy, and provide potential directions for future research.

CONCLUSION

Different microbiota cause changes in the tumour microenvironment through microbial signals thereby affecting immunotherapy efficacy. Translocation of gut microbiota and the role of extraintestinal microbiota in immunotherapy deserve attention. Microbiota regulation is a novel strategy for combination therapy with immunotherapy. Although there are several aspects that deserve further refinement and exploration with regard to administration and clinical translation. Nevertheless, it is foreseeable that the microbiota will become an integral part of cancer treatment.

Exploring the in vitro anti-inflammatory activity of gross saponins of Tribulus terrestris L. fruit by using liquid chromatography-mass spectrometry-based cell metabolomics approach

Our previous studies confirmed the efficacy of gross saponins of Tribulus terrestris L. fruit in treating cerebral ischemia. This study aimed to investigate the related mechanisms in vitro. The lipopolysaccharide-induced BV2 cells model was constructed and treated with gross saponins at different concentrations to explore its anti-inflammatory activity. The cell metabolite changes were tracked by liquid chromatography-mass spectrometry (LC-MS)-based metabolomics, and the metabolic biomarkers and related metabolic pathways were analyzed. Molecular biochemistry analysis was further used to verify the relevant inflammatory pathways. The results showed that the saponins reduced nitric oxide release and the secretion of tumor necrosis factor-alpha, interleukin-1β, and interleukin-6 from lipopolysaccharide-induced BV2 cells. Metabolic perturbations occurred in lipopolysaccharide-treated BV2 cells, which could be reversed by drug treatment via mainly regulating glycerophospholipid metabolism, tryptophan metabolism, purine metabolism pathways, etc. The western blot analysis demonstrated that saponin could suppress the activation of the inflammatory-related signaling pathway. The present study explored the in vitro anti-inflammatory mechanism of gross saponins of Tribulus terrestris L. fruit using an LC-MS-based cell metabolomics approach, which confirms the great potential of LC-MS for drug efficacy evaluation and can be applied in other herbal medicine-related analyses.

Ginsenoside Rg3 enriches SCFA-producing commensal bacteria to confer protection against enteric viral infection via the cGAS-STING-type I IFN axis

The microbiota-associated factors that influence host susceptibility and immunity to enteric viral infections remain poorly defined. We identified that the herbal monomer ginsenoside Rg3 (Rg3) can shape the gut microbiota composition, enriching robust short-chain fatty acid (SCFA)-producing Blautia spp. Colonization by representative Blautia coccoides and Blautia obeum could protect germ-free or vancomycin (Van)-treated mice from enteric virus infection, inducing type I interferon (IFN-I) responses in macrophages via the MAVS-IRF3-IFNAR signaling pathway. Application of exogenous SCFAs (acetate/propionate) reproduced the protective effect of Rg3 and Blautia spp. in Van-treated mice, enhancing intracellular Ca2+- and MAVS-dependent mtDNA release and activating the cGAS-STING-IFN-I axis by stimulating GPR43 signaling in macrophages. Our findings demonstrate that macrophage sensing of metabolites from specific commensal bacteria can prime the IFN-I signaling that is required for antiviral functions.

Hexadecanamide alleviates Staphylococcus aureus-induced mastitis in mice by inhibiting inflammatory responses and restoring blood-milk barrier integrity

Subacute ruminal acidosis (SARA) has been demonstrated to promote the development of mastitis, one of the most serious diseases in dairy farming worldwide, but the underlying mechanism is unclear. Using untargeted metabolomics, we found hexadecanamide (HEX) was significantly reduced in rumen fluid and milk from cows with SARA-associated mastitis. Herein, we aimed to assess the protective role of HEX in Staphylococcus aureus (S. aureus)- and SARA-induced mastitis and the underlying mechanism. We showed that HEX ameliorated S. aureus-induced mastitis in mice, which was related to the suppression of mammary inflammatory responses and repair of the blood-milk barrier. In vitro, HEX depressed S. aureus-induced activation of the NF-κB pathway and improved barrier integrity in mouse mammary epithelial cells (MMECs). In detail, HEX activated PPARα, which upregulated SIRT1 and subsequently inhibited NF-κB activation and inflammatory responses. In addition, ruminal microbiota transplantation from SARA cows (S-RMT) caused mastitis and aggravated S. aureus-induced mastitis, while these changes were reversed by HEX. Our findings indicate that HEX effectively attenuates S. aureus- and SARA-induced mastitis by limiting inflammation and repairing barrier integrity, ultimately highlighting the important role of host or microbiota metabolism in the pathogenesis of mastitis and providing a potential strategy for mastitis prevention.

Propionic Acid Driven by the Lactobacillus johnsonii Culture Supernatant Alleviates Colitis by Inhibiting M1 Macrophage Polarization by Modulating the MAPK Pathway in Mice

In this study, we investigated the effects of Lactobacillus johnsonii on the mouse colitis model. The results showed that the supernatant of the L. johnsonii culture alleviated colitis and remodeled gut microbiota, represented by an increased abundance of bacteria producing short-chain fatty acids, leading to an increased concentration of propionic acid in the intestine. Further studies revealed that propionic acid inhibited activation of the MAPK signaling pathway and polarization of M1 macrophages. Macrophage clearance assays confirmed that macrophages are indispensable for alleviating colitis through propionic acid. In vitro experiments showed that propionic acid directly inhibited the MAPK signaling pathway in macrophages and reduced M1 macrophage polarization, thereby inhibiting the secretion of pro-inflammatory cytokines. These findings improve our understanding of how L. johnsonii attenuates inflammatory bowel disease (IBD) and provide valuable insights for identifying molecular targets for IBD treatment in the future.

Analysis of the gut microbiota in children with gastroesophageal reflux disease using metagenomics and metabolomics

Background

There is no direct evidence of gut microbiota disturbance in children with gastroesophageal reflux disease (GERD). This study aimed to provide direct evidence and a comprehensive understanding of gut microbiota disturbance in children with GERD through combined metagenomic and metabolomic analysis.

Methods

30 children with GERD and 30 healthy controls (HCs) were continuously enrolled, and the demographic and clinical characteristics of the subjects were collected. First, 16S rRNA sequencing was used to evaluate differences in the gut microbiota between children with GERD and HC group, and 10 children with GERD and 10 children in the HC group were selected for metagenomic analysis. Nontargeted metabolomic analysis was performed using liquid chromatography/mass spectrometry (LC/MS), and metagenomic and metabolomic data were analyzed together.

Results

There were significant differences in the gut microbiota diversity and composition between children with GERD and HCs. The dominant bacteria in children with GERD were Proteobacteria and Bacteroidota. At the species level, the top three core bacterial groups were Bacteroides stercoris, Bacteroides vulgatus and Alistipes putredinis. The main differential pathways were identified to be related to energy, amino acid, vitamin, carbohydrate and lipid metabolism. LC/MS detected 288 different metabolites in the positive and negative ion modes between children with GERD and HCs, which were mainly involved in arachidonic acid (AA), tyrosine, glutathione and caffeine metabolism.

Conclusion

This study provides new evidence of the pathogenesis of GERD. There are significant differences in the gut microbiota, metabolites and metabolic pathways between HCs and children with GERD, and the differences in metabolites are related to specific changes in bacterial abundance. In the future, GERD may be treated by targeting specific bacteria related to AA metabolism.

Effects of dietary supplementation of Anoectochilus roxburghii extract (ARE) on growth performance, abdominal fat deposition, meat quality, and gut microbiota in broilers

The broiler industry frequently encounters 2 common problems: excessive deposition of abdominal fat and poor quality of meat. However, there are limited nutritional manipulation strategies to address these issues. While Anoectochilus roxburghii (Wall.) Lindl., a traditional Chinese herb, has been shown to have multiple beneficial effects in humans, its potential roles in broiler chickens remain unexplored. In this study, the effects of dietary supplementation with Anoectochilus roxburghii extract (ARE) on growth performance, abdominal fat deposition, meat quality, blood indices, and gut microbiota were investigated in yellow-feather broiler chickens. A total of 90 twenty-one-day-old yellow-feather broilers were randomly divided into 3 treatments, and each treatment included 5 replicates with 6 birds per replicate. Birds were fed a basal diet supplemented with 0, 0.15, or 0.30% ARE for 6 wk. The results showed that the inclusion of ARE in the diet did not have any significant effect on meat yield (P > 0.05). However, it did lead to a reduction in abdominal fat deposition and an improvement in meat quality (P < 0.05). Mechanistically, the addition of ARE inhibited lipid biosynthesis and enhanced lipid breakdown in both the liver and adipose tissue of the broilers. Furthermore, ARE supplementation increased the antioxidase activities in the muscle and serum of the broilers (P < 0.05). In addition, the supplementation of ARE optimized the diversity and composition of the cecal microbiota, particularly by lowering the ratio of Firmicutes to Bacteroidetes (P < 0.05). Moreover, the abundance of some bacteria that were positively correlated with abdominal fat deposition was reduced by ARE, and vice versa (P < 0.05). Collectively, the results suggest that ARE is a promising candidate as a feed additive for reducing abdominal fat deposition and improving meat quality in the broiler industry.

Hybridization altered the gut microbiota of pigs

Mammalian gut microbiota plays an important role in the host's nutrient metabolism, growth, and immune regulation. Hybridization can enable a progeny to acquire superior traits of the parents, resulting in the hybridization advantage. However, studies on the effects of hybridization on the pigs' gut microbiota are lacking. Therefore, this study used multi-omics technologies to compare and analyze the gut microbiota of the primary wild boar and its offspring. The 16S rRNA gene sequencing results revealed that the gut microbiota of F4 exhibited a host-like dominance phenomenon with a significant increase in the abundance of Lactobacillus and Bifidobacterium. The beta diversity of Duroc was significantly different from those of F0, F2, and F4; after the host hybridization, the similarity of the beta diversity in the progeny decreased with the decrease in the similarity of the F0 lineage. The metagenomic sequencing results showed that the significantly enriched metabolic pathways in F4, such as environmental, circulatory system, fatty acid degradation adaptation, and fatty acid biosynthesis, were similar to those in F0. Moreover, it also exhibited similar significantly enriched metabolic pathways as those in Duroc, such as carbohydrate metabolism, starch and sucrose metabolism, starch-degrading CAZymes, lactose-degrading CAZymes, and various amino acid metabolism pathways. However, the alpha-amylase-related KOs, lipid metabolism, and galactose metabolism in F4 were significantly higher than those in Duroc and F0. Non-targeted metabolome technology analysis found that several metabolites, such as docosahexaenoic acid, arachidonic acid, and citric acid were significantly enriched in the F4 pigs as compared to those in F0. Based on Spearman correlation analysis, Lactobacillus and Bifidobacterium were significantly positively correlated with these metabolites. Finally, the combined metagenomic and metabolomic analysis suggested that the metabolic pathways, such as valine, leucine, and isoleucine biosynthesis and alanine aspartate and glutamate metabolism were significantly enriched in F4 pigs. In conclusion, the gut microbiota of F4 showed a similar host "dominance" phenomenon, which provided reference data for the genetics and evolution of microbiota and the theory of microbial-assisted breeding.

Enterogenic metabolomics signatures of depression: what are the possibilities for the future

INTRODUCTION

An increasing number of studies indicate that the microbiota-gut-brain axis is an important pathway involved in the onset and progression of depression. The responses of the organism (or its microorganisms) to external cues cannot be separated from a key intermediate element: their metabolites.

AREAS COVERED

In recent years, with the rapid development of metabolomics, an increasing amount of metabolites has been detected and studied, especially the gut metabolites. Nevertheless, the increasing amount of metabolites described has not been reflected in a better understanding of their functions and metabolic pathways. Moreover, our knowledge of the biological interactions among metabolites is also incomplete, which limits further studies on the connections between the microbial-entero-brain axis and depression.

EXPERT OPINION

This paper summarizes the current knowledge on depression-related metabolites and their involvement in the onset and progression of this disease. More importantly, this paper summarized metabolites from the intestine, and defined them as enterogenic metabolites, to further clarify the function of intestinal metabolites and their biochemical cross-talk, providing theoretical support and new research directions for the prevention and treatment of depression.

Advances in gut microbiome in metabonomics perspective: based on bibliometrics methods and visualization analysis

Background and aims

Gastrointestinal microbial metabolomics is closely related to the state of the organism and has significant interaction with the pathogenesis of many diseases. Based on the publications in Web of Science Core Collection(WoSCC) from 2004 to 2022, this study conducted a bibliometric analysis of this field, aiming to understand its development trend and frontier, and provide basic information and potential points for in-depth exploration of this field.

Methods

All articles on gastrointestinal flora and metabolism published from 2004 to 2022 were collected and identified in WoCSS. CiteSpace v.6.1 and VOSviewer v.1.6.15.0 were used to calculate bibliometric indicators, including number of publications and citations, study categories, countries/institutions, authors/co-cited authors, journals/co-cited journals, co-cited references, and keywords. A map was drawn to visualize the data based on the analysis results for a more intuitive view.

Results

There were 3811 articles in WoSCC that met our criteria. Analysis results show that the number of publications and citations in this field are increasing year by year. China is the country with the highest number of publications and USA owns the highest total link strength and citations. Chinese Acad Sci rank first for the number of institutional publications and total link strength. Journal of Proteome Research has the most publications. Nicholson, Jeremy K. is one of the most important scholars in this field. The most cited reference is "Gut flora metabolism of phosphatidylcholine promotes cardiovascular disease". Burst detection indicates that Urine, spectroscopy, metabonomic and gut microflora are long-standing hot topics in this field, while autism spectrum disorder and omics are likely to be at the forefront of research. The study of related metabolic small molecules and the application of gastrointestinal microbiome metabolomics in various diseases are currently emerging research directions and frontier in this field.

Conclusion

This study is the first to make a bibliometric analysis of the studies related to gastrointestinal microbial metabolomics and reveal the development trends and current research hotspots in this field. This can contribute to the development of the field by providing relevant scholars with valuable and effective information about the current state of the field.

Gut microbiota and cardiac arrhythmia

One of the most prevalent cardiac diseases is cardiac arrhythmia, however the underlying causes are not entirely understood. There is a lot of proof that gut microbiota (GM) and its metabolites have a significant impact on cardiovascular health. In recent decades, intricate impacts of GM on cardiac arrythmia have been identified as prospective approaches for its prevention, development, treatment, and prognosis. In this review, we discuss about how GM and its metabolites might impact cardiac arrhythmia through a variety of mechanisms. We proposed to explore the relationship between the metabolites produced by GM dysbiosis including short-chain fatty acids(SCFA), Indoxyl sulfate(IS), trimethylamine N-oxide(TMAO), lipopolysaccharides(LPS), phenylacetylglutamine(PAGln), bile acids(BA), and the currently recognized mechanisms of cardiac arrhythmias including structural remodeling, electrophysiological remodeling, abnormal nervous system regulation and other disease associated with cardiac arrythmia, detailing the processes involving immune regulation, inflammation, and different types of programmed cell death etc., which presents a key aspect of the microbial-host cross-talk. In addition, how GM and its metabolites differ and change in atrial arrhythmias and ventricular arrhythmias populations compared with healthy people are also summarized. Then we introduced potential therapeutic strategies including probiotics and prebiotics, fecal microbiota transplantation (FMT) and immunomodulator etc. In conclusion, the GM has a significant impact on cardiac arrhythmia through a variety of mechanisms, offering a wide range of possible treatment options. The discovery of therapeutic interventions that reduce the risk of cardiac arrhythmia by altering GM and metabolites is a real challenge that lies ahead.

Indole metabolites and colorectal cancer: Gut microbial tryptophan metabolism, host gut microbiome biomarkers, and potential intervention mechanisms

Tryptophan (Trp) functions in host-disease interactions. Its metabolism is a multi-pathway process. Indole and its derivatives are Trp metabolites unique to the human gut microbiota. Changes in Trp metabolism have also been detected in colorectal cancer (CRC). Here, combined with the existing CRC biomarkers, we ascribed it to the altered bacteria having the indole-producing ability by making a genomic prediction. We also reviewed the anti-inflammatory and possible anti-cancer mechanisms of indoles, including their effects on tumor cells, the ability to repair the gut barrier, regulation of the host immune system, and provide resistance against oxidative stress. Indole and its derivatives, along with related bacteria, could be targeted as auxiliary strategies to restrain cancer development in the future.

Bamboo Shoots Modulate Gut Microbiota, Eliminate Obesity in High-Fat-Diet-Fed Mice and Improve Lipid Metabolism

Bamboo shoots (BS) have a variety of nutritional benefits; however, their anti-obesity effect and its underlying mechanism of action are still unclear. In this study, we investigated the protective effect of BS against high-fat diet (HFD)-induced gut dysbiosis in mice. After 12 weeks of feeding C57BL/6J mice either on a normal or an HFD with or without BS, metabolic indicators, including blood lipids and glucose tolerance, were measured. 16S rRNA gene sequencing and metabolomics were used to identify alterations in gut microbiota composition and fecal metabolic profiling. The results demonstrated that BS supplementation reduced body weight by 30.56%, mitigated liver damage, and improved insulin resistance and inflammation in obese mice. In addition, BS increased short-chain fatty acid (SCFA) levels and SCFA-producing bacteria (e.g., Lachnospiraceae_NK4A136_group and Norank_f_Muribaculaceae), and reduced levels of harmful bacteria (e.g., Blautia and Burkholderia-Paraburkholderia). Finally, BS increased many beneficial fecal metabolites, such as fatty acids and bile acids, which are highly relevant to the altered gut microbiota. Based on the modulatory effect of BS on microbiota composition and gut metabolite levels observed in this study, we suggest that BS may be beneficial in treating obesity and its related complications.

Gut microbiota and its metabolites in depression: from pathogenesis to treatment

Major depressive disorder is one of the most disabling mental disorders worldwide. Increasing preclinical and clinical studies have highlighted that compositional and functional (e.g., metabolite) changes in gut microbiota, known as dysbiosis, are associated with the onset and progression of depression via regulating the gut-brain axis. However, the gut microbiota and their metabolites present a double-edged sword in depression. Dysbiosis is involved in the pathogenesis of depression while, at the same time, offering a novel therapeutic target. In this review, we describe the association between dysbiosis and depression, drug-microbiota interactions in antidepressant treatment, and the potential health benefits of microbial-targeted therapeutics in depression, including dietary interventions, fecal microbiota transplantation, probiotics, prebiotics, synbiotics, and postbiotics. With the emergence of microbial research, we describe a new direction for future research and clinical treatment of depression.

The effects of traditional Chinese medicine and dietary compounds on digestive cancer immunotherapy and gut microbiota modulation: A review

Digestive tract-related cancers account for four of the top ten high-risk cancers worldwide. In recent years, cancer immunotherapy, which exploits the innate immune system to attack tumors, has led to a paradigm shifts in cancer treatment. Gut microbiota modification has been widely used to regulate cancer immunotherapy. Dietary compounds and traditional Chinese medicine (TCM) can alter the gut microbiota and its influence on toxic metabolite production, such as the effect of iprindole on lipopolysaccharide (LPS), and involvement in various metabolic pathways that are closely associated with immune reactions. Therefore, it is an effective strategy to explore new immunotherapies for gastrointestinal cancer to clarify the immunoregulatory effects of different dietary compounds/TCMs on intestinal microbiota. In this review, we have summarized recent progress regarding the effects of dietary compounds/TCMs on gut microbiota and their metabolites, as well as the relationship between digestive cancer immunotherapy and gut microbiota. We hope that this review will act as reference, providing a theoretical basis for the clinical immunotherapy of digestive cancer via gut microbiota modulation.

Azoxystrobin Disrupts Colonic Barrier Function in Mice via Metabolic Disorders Mediated by Gut Microbiota

The widespread use of azoxystrobin (AZO) over the past few decades has drawn great attention to its environmental health effects. The objective of the present study was to explore the effects of AZO on intestinal barrier function in mice from the perspective of gut microbiota. Specifically, exposure to AZO could cause colonic barrier dysfunction in mice. Meanwhile, AZO could also cause dysbiosis of gut microbiota. Further studies revealed that the metabolic profile of the microbiota was significantly disturbed with AZO exposure. Last but not least, we confirmed that the gut microbiota played a central role in AZO-induced colonic barrier dysfunction through the gut microbiota transplantation experiment. Gut microbiota mediated colonic barrier dysfunction induced by AZO via inducing dysbiosis of the microbiota metabolic profile. The findings of this study strongly support a new insight that the gut microbiota can be a key target of health risks of pesticides.

The Impact of Food Additives on the Abundance and Composition of Gut Microbiota

The gut microbiota has been confirmed as an important part in human health, and is even take as an 'organ'. The interaction between the gut microbiota and host intestinal environment plays a key role in digestion, metabolism, immunity, inflammation, and diseases. The dietary component is a major factor that affects the composition and function of gut microbiota. Food additives have been widely used to improve the color, taste, aroma, texture, and nutritional quality of processed food. The increasing variety and quantity of processed food in diets lead to increased frequency and dose of food additives exposure, especially artificial food additives, which has become a concern of consumers. There are studies focusing on the impact of food additives on the gut microbiota, as long-term exposure to food additives could induce changes in the microbes, and the gut microbiota is related to human health and disease. Therefore, the aim of this review is to summarize the interaction between the gut microbiota and food additives.

Short Chain Fatty Acid Metabolism in Relation to Gut Microbiota and Genetic Variability

It is widely accepted that the gut microbiota plays a significant role in modulating inflammatory and immune responses of their host. In recent years, the host-microbiota interface has gained relevance in understanding the development of many non-communicable chronic conditions, including cardiovascular disease, cancer, autoimmunity and neurodegeneration. Importantly, dietary fibre (DF) and associated compounds digested by the microbiota and their resulting metabolites, especially short-chain fatty acids (SCFA), were significantly associated with health beneficial effects, such as via proposed anti-inflammatory mechanisms. However, SCFA metabolic pathways are not fully understood. Major steps include production of SCFA by microbiota, uptake in the colonic epithelium, first-pass effects at the liver, followed by biodistribution and metabolism at the host's cellular level. As dietary patterns do not affect all individuals equally, the host genetic makeup may play a role in the metabolic fate of these metabolites, in addition to other factors that might influence the microbiota, such as age, birth through caesarean, medication intake, alcohol and tobacco consumption, pathogen exposure and physical activity. In this article, we review the metabolic pathways of DF, from intake to the intracellular metabolism of fibre-derived products, and identify possible sources of inter-individual variability related to genetic variation. Such variability may be indicative of the phenotypic flexibility in response to diet, and may be predictive of long-term adaptations to dietary factors, including maladaptation and tissue damage, which may develop into disease in individuals with specific predispositions, thus allowing for a better prediction of potential health effects following personalized intervention with DF.

New insights into bacterial mechanisms and potential intestinal epithelial cell therapeutic targets of inflammatory bowel disease

The global incidence of inflammatory bowel disease (IBD) has increased rapidly in recent years, but its exact etiology remains unclear. In the past decade, IBD has been reported to be associated with dysbiosis of gut microbiota. Although not yet proven to be a cause or consequence of IBD, the common hypothesis is that at least some alterations in the microbiome are protective or pathogenic. Furthermore, intestinal epithelial cells (IECs) serve as a protective physical barrier for gut microbiota, essential for maintaining intestinal homeostasis and actively contributes to the mucosal immune system. Thus, dysregulation within the intestinal epithelium increases intestinal permeability, promotes the entry of bacteria, toxins, and macromolecules, and disrupts intestinal immune homeostasis, all of which are associated with the clinical course of IBD. This article presents a selective overview of recent studies on bacterial mechanisms that may be protective or promotive of IBD in biological models. Moreover, we summarize and discuss the recent discovery of key modulators and signaling pathways in the IECs that could serve as potential IBD therapeutic targets. Understanding the role of the IECs in the pathogenesis of IBD may help improve the understanding of the inflammatory process and the identification of potential therapeutic targets to help ameliorate this increasingly common disease.

Gut microbiota in ischemic stroke: Where we stand and challenges ahead

Gut microbiota is increasingly recognized to affect host health and disease, including ischemic stroke (IS). Here, we systematically review the current understanding linking gut microbiota as well as the associated metabolites to the pathogenesis of IS (e.g., oxidative stress, apoptosis, and neuroinflammation). Of relevance, we highlight that the implications of gut microbiota-dependent intervention could be harnessed in orchestrating IS.

Chronic lead exposure exacerbates hepatic glucolipid metabolism disorder and gut microbiota dysbiosis in high-fat-diet mice

Lead (Pb) and obesity are co-occurring risk factors for metabolic disorders. However, there is still a lack of study on the combined effects of both stressors on metabolism. C57BL/6J mice were exposed to 200 mg/L Pb or/and HFD for 24 weeks and were used to investigate the effects and underlying mechanisms of chronic Pb exposure on obese mice. The results showed that Pb significantly increased body weight, visceral obesity, fasting blood glucose levels, and insulin resistance, and aggravated liver damage, hepatic lipid accumulation and steatosis in HFD-fed mice. Further analysis showed that Pb significantly inhibited insulin signaling pathway PI3K/AKT and fatty acid β-oxidation, and accelerated fatty acid synthesis. Moreover, Pb exacerbated HFD-induced disruption of gut microbiota homeostasis, manifested by increased proportions of pathogenic genera such as Desulfovibrio, Alistipes and Helicobacter, and decreased proportions of beneficial microbes Akkermansia and Barnesiella, which were negatively associated with obesity. These results indicated that Pb exposure exacerbated the disruption of liver glucolipid metabolism in HFD mice possibly by disrupting gut microbiota.

Comparison of Changes in Gut Microbiota in Wild Boars and Domestic Pigs Using 16S rRNA Gene and Metagenomics Sequencing Technologies

Simple Summary

The microbiota co-evolves with the host and plays an important role in the host's health, immunity, and nutrient absorption. Wild boars are the ancestors of domestic pigs. During the long evolutionary process, the physiological structure and living habits of modern pigs have undergone tremendous changes. However, there are few studies on the evolution of gut microbiota of wild boars and domestic pigs. In this study, by comparing the changes in the composition and function of the gut microbiota of wild boars and domestic pigs, it was found that there were significant differences between the two groups, which indicated that the gut microbiota had changed during the evolution process. This study provides some data references for the evolution of gut microbiota.

Abstract

Gut microbiota diversity is a result of co-evolution between microorganisms and their hosts. However, there are few studies on the evolution of the gut microbiota of wild boars and domestic pigs. Therefore, this study aimed to analyze the composition and function of the gut microbiota of wild boars and domestic pigs using 16S rRNA gene V3-V4 region sequencing, 16S rRNA gene full-length sequencing, and metagenomic sequencing. This study showed that after a long evolution, as compared to wild boars, the domestic pigs exhibited significantly increased relative abundances of Lactobacillus, Lactobacillus reuteri, Lactobacillus johnsonii, Lactobacillus sp.DJF_WC5, and Lactobacillus; s_uncultured bacterium, while the relative abundances of Bifidobacterium and Methanococcaceae decreased significantly. In addition, the relative abundances of “carbohydrate metabolism”, “starch and sucrose metabolism”, “valine, leucine, and isoleucine biosynthesis”, “lysine biosynthesis”, and starch-degrading CAZymes were significantly increased in the domestic pigs, while the relative abundances of “environmental adaptation”, “immune system”, “fatty acid degradation and synthesis”, and cellulose-hemicellulose-degrading CAZymes were significantly increased in the wild boars. Finally, the diversity of ARGs and the “antimicrobial resistance genes” in domestic pigs also increased significantly. This study illustrates that the gut microbiota composition and function of wild boars and domestic pigs changed during the long evolution process. These findings provide a basic research theory for the evolution of gut microbiota and the treatment of health and disease.

Dietary Tryptophan-Mediated Aryl Hydrocarbon Receptor Activation by the Gut Microbiota Alleviates Escherichia coli-Induced Endometritis in Mice

Intestinal microbiota-mediated aryl hydrocarbon receptor (AhR) activation plays an important role in host-microbiota interactions and disease development. However, whether AhR activation mediates infection-induced inflammation in remote organs is not clear. The purpose of this study is to assess the effects and underlying mechanism of AhR activation and gut microbiota-mediated dietary tryptophan (Trp) metabolism on infection-induced inflammation using an Escherichia coli (E. coli)-induced endometritis model in mice. We found that AhR activation by 6-formylindolo (3,2-b) carbazole (Ficz), which is an AhR agonist derived from the photooxidation of Trp, alleviated E. coli-induced endometritis by repairing barrier function and inhibiting inflammatory responses, while inhibition of AhR by CH223191, which is a synthetic AhR antagonist, aggravated E. coli-induced endometritis. Gut dysbiosis damaged AhR activation and exacerbated E. coli-induced endometritis in mice, which responded to the reduced abundance of AhR ligand producers, such as Lactobacillus spp. Supplementation with dietary Trp ameliorated E. coli-induced endometritis in a microbiota-dependent manner, which was associated with the production of AhR ligands. Administration of AhR ligands, including indole and indole aldehyde, but not indole-3-propionic acid, rescued the protective effect of Trp on E. coli-induced endometritis in dysbiotic mice. Moreover, consumption of Lactobacillus reuteri (L. reuteri) containing AhR ligand-producing capability also alleviated E. coli-induced endometritis in mice in an AhR-dependent manner. Our results demonstrate that microbiota-mediated AhR activation is a key factor in fighting pathogen-caused inflammation, which leads to a potential strategy to regulate the gut microbiota and metabolism by dietary Trp or probiotics for the intervention of infectious diseases and reproductive health. IMPORTANCE Infection-induced endometritis is a common and frequently occurring disease in humans and animals. Accumulating evidence suggests an important role of the gut microbiota in the development of infection-induced inflammation. Whether and how gut microbiota-mediated AhR activation regulates the pathogenesis of pathogen-induced endometritis remains unknown. The current study found that AhR activation ameliorated E. coli-induced endometritis, and inhibition of AhR produced negative results. Gut dysbiosis reduced the abundance of AhR ligand producers including Lactobacillus spp., damaged AhR activation, and exacerbated E. coli-induced endometritis. Supplementation with dietary Trp, AhR ligands, and L. reuteri containing AhR ligand-producing capability alleviated E. coli-induced endometritis in mice. Our results suggest an important role of microbiota-mediated AhR activation in the pathogenesis of endometritis and provide potential strategies for the intervention of infectious diseases and reproductive health by regulating the gut microbiota and metabolism.

Moringa oleifera Lam. Peptide Remodels Intestinal Mucosal Barrier by Inhibiting JAK-STAT Activation and Modulating Gut Microbiota in Colitis

Ulcerative colitis is a chronic inflammatory bowel disease (IBD), but progress in exploring its pathogenesis and finding effective drugs for its prevention and treatment has stalled in recent years. The seeds of Moringa oleifera Lam. are rich in proteins known to have multiple physiological activities. In our earlier work, we had isolated and purified a peptide (MOP) having the sequence KETTTIVR, from M. oleifera seeds; however, its anti-inflammatory activity and mechanism in vivo were unclear. Here we used the dextran sulfate sodium (DSS)-induced colitis model to study the anti-inflammatory activity and mechanism of this MOP. Our results are the first to show that MOP can ameliorate the pathological phenotype, inflammation, and intestinal barrier disruption in mice with colitis. Furthermore, RNA sequencing revealed that MOP inhibits the Janus kinase/signal transducer and activator of transcription (JAK-STAT) pathway activation. Next, by using 16s rRNA gene sequencing, we found that MOP can ameliorate DSS-induced gut microbiota dysbiosis. In addition, an untargeted metabolomics analysis suggested that MOP is able to modulate the level of lipid and amino acid metabolites in IBD-stricken mice. Altogether, these results indicate that MOP ameliorates colitis by remodeling intestinal mucosal barrier by inhibiting JAK-STAT pathway’s activation and regulating gut microbiota and its metabolites, thus providing a basis for further processing and design of bioactive foods from M. oleifera seeds.

Bile acids promote the caveolae-associated entry of swine acute diarrhea syndrome coronavirus in porcine intestinal enteroids

Intestinal microbial metabolites have been increasingly recognized as important regulators of enteric viral infection. However, very little information is available about which specific microbiota-derived metabolites are crucial for swine enteric coronavirus (SECoV) infection in vivo. Using swine acute diarrhea syndrome (SADS)-CoV as a model, we were able to identify a greatly altered bile acid (BA) profile in the small intestine of infected piglets by untargeted metabolomic analysis. Using a newly established ex vivo model–the stem cell-derived porcine intestinal enteroid (PIE) culture–we demonstrated that certain BAs, cholic acid (CA) in particular, enhance SADS-CoV replication by acting on PIEs at the early phase of infection. We ruled out the possibility that CA exerts an augmenting effect on viral replication through classic farnesoid X receptor or Takeda G protein-coupled receptor 5 signaling, innate immune suppression or viral attachment. BA induced multiple cellular responses including rapid changes in caveolae-mediated endocytosis, endosomal acidification and dynamics of the endosomal/lysosomal system that are critical for SADS-CoV replication. Thus, our findings shed light on how SECoVs exploit microbiome-derived metabolite BAs to swiftly establish viral infection and accelerate replication within the intestinal microenvironment.

Bile acids (BAs), a commonly studied category of microbial metabolites, have long been acknowledged to have proviral or antiviral activities. Recent studies using different swine enteric coronaviruses (SECoVs) showed that BA play an important role in regulating viral replication in vitro. A mechanistic understanding of how BA regulates SECoV replication in small intestinal enterocytes is lacking. Herein, we utilized an emerging highly pathogenic SECoV, swine acute diarrhea syndrome (SADS)-CoV, which possesses the potential for zoonotic transmission, to investigate the crucial role of BA in modulating viral replication in porcine intestinal enteroids (PIEs). Our observations explain how BAs acts on epithelial cells to enhance SADS-CoV replication by inducing caveolae-mediated endocytosis and endosomal acidification, altering the dynamics of viral trafficking through the cellular endosomal/lysosomal system. Our results shed light on the role of BAs in the rapid establishment of SECoV infection within the intestinal microenvironment.

Polysaccharides from soybean residue fermented by Neurospora crassa alleviate DSS-induced gut barrier damage and microbiota disturbance in mice

Soluble polysaccharides derived from microbial fermentation of agricultural by-products were considered as potential functional ingredients, primarily having probiotic properties. Herein, soluble polysaccharides (FSRP) were isolated from soybean residue fermented by Neurospora crassa, and FSRP mainly contained rhamnose, arabinose, fucose, mannose, glucose, and galactose, according to GC-MS analysis. To further investigate the protective effect of FSRP against colitis, dextran sulfate sodium induction (DSS)-treated mice were orally gavaged with FSRP (200 mg kg-1 d-1) or inulin (400 mg kg-1 d-1, a positive control) for 7 d. The results showed that DSS-treated mice displayed symptoms of body weight loss, atrophy, and histopathological changes of colon, as well as gut barrier damage, which were recovered after FSRP supplementation (similar to inulin). Furthermore, the beneficial effects of FSRP were linked to a decreased inflammatory response and increased protein expression of E-cadherin, claudin-1 and ZO-1. Illumina-MiSeq sequencing analysis revealed that FSRP increased microbial diversity and altered community structure. Specifically, FSRP could modulate the abundance of inflammation-related bacteria (such as Tenericutes, Clostridia, and Bacilli) to ameliorate colitis symptoms. Therefore, FSRP can relieve DSS-induced colitis, which is closely associated with reduced levels of inflammatory factors, improved gut barrier function and gut microbiota homeostasis.

Pu-erh Tea Restored Circadian Rhythm Disruption by Regulating Tryptophan Metabolism

Pu-erh tea is a healthy beverage rich in phytochemicals, and its effect on the risk of inducing circadian rhythm disorders (CRD) is unclear. In this study, healthy mice were given water or 0.25% (w/v) Pu-erh tea for 7 weeks, followed by a 40 day disruption of the light/dark cycle. CRD caused dysregulation of neurotransmitter secretion and clock gene oscillations, intestinal inflammation, and disruption of intestinal microbes and metabolites. Pu-erh tea boosted the indole and 5-hydroxytryptamine pathways of tryptophan metabolism via the gut-liver-brain axis. Furthermore, its metabolites (e.g., IAA, Indole, 5-HT) enhanced hepatic glycolipid metabolism and down-regulated intestinal oxidative stress by improving the brain hormone release. Tryptophan metabolites and bile acids also promoted liver lipid metabolism and inhibited intestinal inflammation (MyD88/NF-κB) via the enterohepatic circulation. Collectively, 0.25% (w/v) Pu-erh tea has the potential to prevent CRD by promoting indole and 5-HT pathways of tryptophan metabolism and signaling interactions in the gut-liver-brain axis.

Fucoidan Is Not Completely Dependent on Degradation to Fucose to Relieve Ulcerative Colitis

Recently, fucoidan has been proposed for use as a potential anti-inflammatory drug. The purpose of this study was to investigate the mechanism of fucoidan in the treatment of ulcerative colitis. We compared the anti-inflammatory effects of fucoidan and fucose induced by dextran sulfate sodium, and the effects of fucoidan and fucose on the gut microbiota of mice. Our results showed that low-dose fucoidan significantly improved weight loss, disease activity index scores, colonic shortening, colonic histopathological damage, intestinal fatty acid binding protein 2 levels, and the expression of Occludin, Claudin-4, and Claudin-1. However, both high-dose fucoidan and fucose did not perform as well as low-dose fucoidan as described above. In addition, 16S rDNA high-throughput sequencing showed that low-dose fucoidan significantly increased the abundance of Alloprevotella, and fucose significantly increased Ruminococcaceae, but neither significantly reversed the imbalance in the gut microbiota. Therefore, we inferred that the regulation of fucoidan on colitis has a unique and complex mechanism, and it is not completely dependent on degradation to fucose to relieve ulcerative colitis, nor is it achieved only by regulating the gut microbiota. The mechanism by which fucoidan treats colitis may also include reducing inflammatory cell infiltration and increasing intestinal barrier function.

Chemogenetics defines a short-chain fatty acid receptor gut-brain axis

Volatile small molecules, including the short-chain fatty acids (SCFAs), acetate and propionate, released by the gut microbiota from the catabolism of nondigestible starches, can act in a hormone-like fashion via specific G-protein-coupled receptors (GPCRs). The primary GPCR targets for these SCFAs are FFA2 and FFA3. Using transgenic mice in which FFA2 was replaced by an altered form called a Designer Receptor Exclusively Activated by Designer Drugs (FFA2-DREADD), but in which FFA3 is unaltered, and a newly identified FFA2-DREADD agonist 4-methoxy-3-methyl-benzoic acid (MOMBA), we demonstrate how specific functions of FFA2 and FFA3 define a SCFA-gut-brain axis. Activation of both FFA2/3 in the lumen of the gut stimulates spinal cord activity and activation of gut FFA3 directly regulates sensory afferent neuronal firing. Moreover, we demonstrate that FFA2 and FFA3 are both functionally expressed in dorsal root- and nodose ganglia where they signal through different G proteins and mechanisms to regulate cellular calcium levels. We conclude that FFA2 and FFA3, acting at distinct levels, provide an axis by which SCFAs originating from the gut microbiota can regulate central activity.