Ruminococcus gnavus plays a pathogenic role in diarrhea-predominant irritable bowel syndrome by increasing serotonin biosynthesis

Why do babies cry? Exploring the role of the gut microbiota in infantile colic, constipation, and cramps in the KOALA birth cohort study

Gastrointestinal symptoms are common during infancy, including infantile colic. Colic can be loosely defined as prolonged and recurrent crying without obvious cause. The cause indeed remains unclear despite much research. Results on infant nutrition are inconclusive, but prior work has linked maternal mental health to infant crying. Recently, several small studies have described associations between gut microbiota and colic. We used a larger cohort to examine the role of the microbiota in infant gastrointestinal health, while also accounting for other biopsychosocial factors. Using fecal 16S rRNA gene amplicon sequencing data from 1,012 infants in the KOALA birth cohort, we examined associations between the 1-month gut microbiota and parent-reported functional gastrointestinal symptoms throughout infancy, including colic, constipation, and cramps. These analyses were adjusted for biopsychosocial factors that were associated with symptoms in a broader analysis involving 2,665 participants. In 257 infants, we also explored associations between breastmilk human milk oligosaccharides (HMOs) and gastrointestinal symptoms. Higher relative abundance of Staphylococcus at one month was associated with less constipation in the first three months of life. Conversely, Ruminococcus gnavus group abundance was associated with more colicky symptoms, particularly between four and seven months. Breastmilk concentrations of the HMOs lacto-N-hexaose (LNH) and lacto-N-neohexaose (LNnH) were associated with less constipation in the first three months. Our results support the conclusion that gut microbiota are relevant in infantile colic and constipation. However more work is needed to elucidate the underlying mechanisms, and explore their interplay with other relevant biopsychosocial factors such as maternal mental health.

Mechanosensory Piezo2 regulated by gut microbiota participates in the development of visceral hypersensitivity and intestinal dysmotility

The gut microbiota plays a crucial role in the manifestation of intestinal dysfunction associated with irritable bowel syndrome (IBS). The mechanosensory Piezo2 has been implicated in the regulation of intestinal function. However, it remains unclear whether Piezo2 is modulated by the gut microbiota, thus contributing to the development of visceral hypersensitivity and gut dysmotility. The study enrolled patients with diarrhea-predominant IBS (IBS-D) alongside healthy controls (HC). Questionnaires, rectal barostat test, and colonoscopy with mucosal biopsy were conducted. Fecal microbiota transplantation (FMT) was performed using samples from HC or IBS-D patients, and interventions with Akkermansia muciniphila or Fusobacterium varium were carried out on colon- or dorsal root ganglion (DRG)- Piezo2 knockdown pseudo-germ-free mice. Visceral sensitivity and intestinal motility were assessed. Piezo2 levels were detected using western blot and immunofluorescence. Fecal 16S rRNA sequencing and cecum untargeted metabolomics analysis, followed by molecular docking predictions of Piezo2, were also performed. The ratio of Piezo2+/5-HT+ cells was lower in IBS-D patients, positively correlated with visceral sensation and intestinal dysbiosis. The mice that received FMT from IBS-D patients exhibited colonic dysmotility and visceral hypersensitivity, along with elevated Piezo2 protein levels in the colon and DRG. Knockdown of Piezo2 in the colon or DRG ameliorated the FMT-induced colonic dysmotility and visceral hypersensitivity. Fecal 16S rRNA sequencing revealed distinct microbiota composition. Notably, Fusobacterium varium, but not Akkermansia muciniphila, induced gut dysmotility and visceral hypersensitivity, effects that could be alleviated by colon or DRG Piezo2 knockdown. Additionally, Fusobacterium varium lead to increased Piezo2 protein levels, as well as elevated levels of indole-3-acetic acid and indole-3-acrylic acid, which were predicted to bind to Piezo2, causing disturbances. Piezo2 can be regulated by gut microbiota and involved in visceral hypersensitivity and colonic dysmotility, with Fusobacterium varium playing a crucial role.

Modulating autism spectrum disorder pathophysiology using a trace amine-focused approach: targeting the gut

Autism spectrum disorder (ASD) affects approximately 1% of the population directly, but also a much higher proportion (family and caregivers) indirectly. Although ASD is characterized by high prevalence of anxiety and poor gastrointestinal health, current treatment strategies are mainly focused on neurological symptomatic treatment, with little to no attention to gut health. Furthermore, many psychiatric drugs used for management of secondary neurological symptoms, are known to exacerbate gut health issues and neurological dysregulation across the gut-brain axis.Trace amines are neurotransmitter-like substances synthesized endogenously in the human brain - in trace amounts - but also in high abundance by the microbiome. Emerging evidence suggests dysregulation of the trace amine system in ASD. Since trace aminergic signalling is central to regulatory system homeostasis, we hypothesize targeting this system in the ASD context. Given the various sources of trace amines, we suggest that normalization of functional dysbiosis in terms of trace aminergic signalling - rather than microbial compositional dysbiosis - should be a focus in medicines development. In addition, a holistic consideration including also other factors at play in determining trace aminergic signalling outcome - such as receptor binding, enzymatic role players, etc. - is required to fully elucidate and therapeutically modify the pathophysiology of regulatory systems implicated in ASD.This review firstly provides a brief overview of trace amine dysregulation in ASD for context. Secondly, we formulate our hypothesis on how this may therapeutically address symptomology, with consideration of cellular and molecular mechanism interplay across the gut-brain axis. Finally, we provide a critical assessment of advances in therapeutics development and drug re-purposing, gaps in knowledge and priorities for medicines development going forward.

The relationship between tryptophan metabolism and gut microbiota: Interaction mechanism and potential effects in infection treatment

Human health is influenced by the gut microbiota, particularly in aspects of host immune homeostasis and intestinal immune response. Tryptophan (Trp) not only acts as a nutrient enhancer but also plays a critical role in the balance between host immune tolerance and gut microbiota maintenance. Both endogenous and bacterial metabolites of Trp, exert significant effects on gut microbial composition, microbial metabolism, the host immunity and the host-microbiome interface. Trp metabolites regulate host immunity by activating aryl hydrocarbon receptor (AhR), thereby contributing to immune homeostasis. Among Trp metabolites, AhR ligands include endogenous metabolites (such as kynurenine), and bacterial metabolites (such as indole and its derivatives). Here, we present a comprehensive analysis of the relationships between Trp metabolism and 14 key microbiota, encompassing fungi (e.g., Candida albicans, Aspergillus), bacteria (e.g., Ruminococcus gnavus, Bacteroides, Prevotella copri, Clostridium difficile, Escherichia coli, lactobacilli, Mycobacterium tuberculosis, Pseudomonas aeruginosa, Staphylococcus aureus, Helicobacter. Pylori), and viruses (e.g., SARS-CoV-2, influenza virus). This review clarifies how the gut microbiota regulates Trp metabolism and uncovers the underlying mechanisms of these interactions. And increased mechanistic insight into how the microbiota modulate the host immune system through Trp metabolism may allow for the identification of innovative therapies that are specifically designed to target Trp absorption, Trp metabolites, the gut microbiota, or interactions between Trp and gut microbiota to treat both intestinal and extra-intestinal inflammation as well as microbial infections.

Chinese yam (Dioscorea) polysaccharide ameliorates ulcerative colitis in mice via modulating disorders of intestinal microecology and metabolism

Clinical research has demonstrated that non-starch polysaccharides from natural sources exhibit protective and therapeutic effects on ulcerative colitis (UC). In this study, a non-starch polysaccharide (CYP-A) with a molecular weight of 1.54 × 103 kDa was isolated from a speciality Chinese yam (Dioscorea) variety, the Ma yam, consisting mainly of mannose and glucose. The results indicated that CYP-A alleviated colitis symptoms induced by dextran sulfate sodium (DSS), repaired the mucus barrier, and protected the integrity of the intestinal mechanical barrier. Furthermore, CYP-A suppressed pro-inflammatory cytokine production, reduced oxidative stress, and modulated the biological barriers by facilitating the colonization of norank_f-_Muribaculaceae, Dubosella, Faecalibaculum and Enterorhabdus, while reducing Escherichia-Shigella and Bacteroides. Notably, CYP-A reshaped the metabolic pathways related to steroid hormone biosynthesis as well as phenylalanine, tyrosine, and histidine metabolism. These findings highlight the potential of CYP-A as a nutraceutical for targeting UC and improving gut health.

Circadian rhythm perturbation causes IBS-like characteristics and altered fecal metabolome in mice

BACKGROUND

Circadian rhythm disturbance is associated with functional gastrointestinal disorders such as irritable bowel syndrome (IBS). This study aimed to explore the effects of dysregulated circadian rhythm on visceral sensitivity, colonic permeability, gut microbial composition, and metabolism in mice.

METHODS

A murine model of circadian rhythm disturbance was built by performing a 6-hour phase delay. Visceral sensitivity was assessed using the abdominal withdrawal reflex score through colorectal distention. Colonic permeability was determined by measuring transepithelial resistance (TEER) and the permeability of fluorescent dextran 4 kDa. To gain insight into gut microbial composition and metabolism, 16S rRNA sequencing and untargeted metabolomics were conducted, respectively.

RESULTS

Circadian rhythm disturbance led to IBS-like characteristics in mice, including visceral hypersensitivity and colonic hyperpermeability. Disrupted circadian rhythm also resulted in a decrease in intestinal microbial diversity and alterations in microbial structure. Several microbial genera were influenced by circadian rhythm disturbance, such as Bacteroides, Bifidobacterium, Desulfovibrio, Dubosiella, and Erysipelatoclostridium. Moreover, disrupted circadian rhythm altered metabolic profiles of gut microbiota and affected the levels of various metabolites, including 1-methylhistamine, nitrosylhaem, 3-aminocaproic acid, boviquinone, and carboplatin. Finally, circadian rhythm disturbance altered the relationship between microbial genera and metabolites.

CONCLUSION

Circadian rhythm disturbance contributes to visceral hypersensitivity and colonic hyperpermeability, while also altering the composition and metabolism of gut microbiota.

Gut Expansion of a Human Lupus Pathobiont is Associated With Autoantibody Production and T Cell Dysregulation

OBJECTIVE

The mechanisms by which the gut microbiome contributes to lupus pathogenesis remain poorly understood. The anaerobe Ruminococcus gnavus (RG) expands in patients with lupus in association with flares. The goal of this study was to determine the mechanisms by which candidate pathobiont lipoglycan-producing RG2 may contribute to autoimmunity and to identify factors promoting its expansion.

METHODS

The consequences of RG colonization or depletion were evaluated in the B6.Sle1.Sle2.Sle3 triple congenic (TC) lupus model by flow cytometry and enzyme-linked immunosorbent assay. RG lysates were tested on Treg cells in vitro. Fecal microbiota transfers evaluated the contribution of the microbiome origin from lupus or control donors and dietary tryptophan. RG1 and RG2 growth and metabolome were evaluated in response to tryptophan in vitro.

RESULTS

Only RG2 stably colonized TC mice, in which it induced autoantibody production and T cell activation. Depletion of anaerobes had the opposite effect, with an increased Treg frequency. RG2 induced Treg apoptosis in cocultures with dendritic cells. RG is present in TC microbiota, from which it is amplified by tryptophan. The combination of TC microbiota and high dietary tryptophan induced autoimmune activation and intestinal inflammation in healthy control mice. Finally, tryptophan enhanced RG2 growth and production of immunomodulatory metabolites.

CONCLUSION

RG2 contributes to autoimmune activation, at least by inducing Treg apoptosis. The expansion of this pathobiont is promoted by host genetic factors and tryptophan metabolism. Thus, targeted RG2 depletion may improve disease outcomes in patients with lupus.

Suppression of Alzheimer's disease by Agaricus sinodeliciosus var. Chaidam exopolysaccharide with amyloid-β clearance activity via gut microbiota-metabolite regulation

Amyloid-β (Aβ) aggregation is a hallmark of Alzheimer's disease (AD), characterized by cognitive impairment, and there remains a lack of effective functional compound with Aβ clearance activity. To elucidate the effect of exopolysaccharide (EPS) extracted from Agaricus sinodeliciosus var. Chaidam on Aβ1-42- induced AD rat and uncover the underlying mechanism, the neuroprotective activity of EPS was evaluated using immunofluorescence, immunohistochemistry, western blot, RT-qPCR, microbiomics and metabolomics. The results demonstrated that EPS exhibited significant anti-AD efficacy, as evidenced by improved cognitive function and spatial memory, balanced brain redox status, suppressed neuroinflammatory responses. EPS substantially reduced Aβ1-42 accumulation in the hippocampus by activating Aβ-phagocytic microglia through the mTOR-HIF-1α pathway. Importantly, EPS reconstructed gut microbiota composition by increasing the relative abundance of Ruminococcaceae and reduced Erysipelotrichaceae. The reshaped gut microbiome and the formation of the metabolite serotonin were associated with behavioral alterations, neuroinflammation, and brain oxidative status. Thus, EPS significantly alleviated cognitive deficit and neuroinflammation in Aβ1-42-induced AD rats, potentially by enhancing microglial phagocytosis of Aβ1-42 and modulating the gut microbiome and serotonin production. Collectively, EPS from A. sinodeliciosus var. Chaidam polysaccharide may serve as a novel Aβ1-42-targeted approach for anti-AD therapy.

Mechanistic Implications of the Mediterranean Diet in Patients With Newly Diagnosed Crohn's Disease: Multiomic Results From a Prospective Cohort

BACKGROUND & AIMS

To decipher the mechanisms underlying the protective role of the Mediterranean diet (MED) in Crohn's disease (CD), we explored the implications of adherence to MED on CD course, inflammatory markers, and microbial and metabolite composition.

METHODS

Patients with newly diagnosed CD were recruited and followed prospectively. MED adherence was assessed by repeated food frequency questionnaires (FFQs) using a predefined inflammatory bowel disease Mediterranean diet score (IBDMED score), alongside validated MED adherence screeners. Crohn's disease activity index (CDAI), C-reactive protein, fecal calprotectin, and microbial composition (16S-ribosomal RNA sequencing) were assessed each visit. Baseline serum and fecal samples were analyzed for targeted quantitative metabolomics.

RESULTS

Consecutive patients: 271 (52% men, average age 31 ± 12 years, B1 phenotype 75%). FFQs collected: 636 (range 1-5 FFQs per patient). Adherence to MED was associated with a noncomplicated CD course, and inversely correlated with CDAI, fecal calprotectin, C-reactive protein, and microbial dysbiosis index (all P < .05). Increasing adherence to MED over time correlated with reduced CDAI and inflammatory markers (P < .05). Adherence to MED correlated with a microbial cluster of commensals and short-chain fatty acid producers including Faecalibacterium, and with plant metabolites, vitamin derivatives, and amino acids. Conversely, adherence to MED inversely correlated with a cluster of oral genera, Escherichia coli and Ruminococcus gnavus, known CD-associated species, and with tryptophan metabolites, ceramides, and primary bile acids (false discovery rate < 0.2).

CONCLUSION

Adherence to MED is associated with beneficial clinical outcomes and decreased inflammatory markers. These may be driven by lower levels of primary bile acids and microbial dysbiosis and a beneficial microbial and metabolite composition. Randomized controlled trials are needed to evaluate the role of MED in CD management.

Human gut microbiota adaptation to high-altitude exposure: longitudinal analysis over acute and prolonged periods

This study investigated the longitudinal effects of acute (7-day) and prolonged (3-month) high-altitude exposure on gut microbiota in healthy adult males, addressing the limited data available in human populations. A cohort of 406 healthy adult males was followed, and fecal samples were collected at three time points: baseline at 800 m (406 samples), 7 days after ascending to 4,500 m (406 samples), and 2 weeks post-return to 800 m following 3 months at high altitude (186 samples). High-throughput 16S ribosomal DNA sequencing was employed to analyze microbiota composition and diversity. Results revealed significant changes in alpha- and beta-diversity, with acute high-altitude exposure inducing more pronounced effects compared to prolonged exposure. Specifically, acute exposure increased opportunistic pathogens (Ruminococcus and Oscillibacter) but decreased beneficial short-chain fatty acid producers (Faecalibacterium and Bifidobacterium). Notably, these changes in microbiota persisted even after returning to low altitude, indicating long-term remodeling. Functional analyses revealed substantial changes in metabolic pathways, suggesting microbiota-driven adaptations to energy utilization under high-altitude hypoxic conditions. In summary, acute high-altitude exposure caused dramatic changes in gut microbiota, while prolonged exposure led to structural and functional reshaping. These findings enhance our understanding of how high-altitude environments reshape gut microbiota.

IMPORTANCE

This study is the first to investigate the impact of high-altitude exposure on gut microbiota adaptation in a large-scale longitudinal cohort. It seeks to enhance understanding of how high-altitude environments reshape gut microbiota. Acute exposure to high altitude significantly affected both α-diversity and β-diversity of gut microbiota, with acute exposure causing more pronounced changes than prolonged adaptation, indicating temporary disruptions in microbial communities. Notable shifts in microbial abundance were observed, including increased levels of genera linked to hypoxic stress (e.g., Gemmiger, Ruminococcus, and Parabacteroides) and decreased levels of beneficial bacteria (e.g., Faecalibacterium, Roseburia, and Bifidobacterium), suggesting possible adverse health effects. Functional analysis indicated changes in metabolism-related pathways post-exposure, supporting the idea that high-altitude adaptations involve metabolic adjustments for energy management. These findings enhance understanding of high-altitude physiology, illustrating the role of gut microbiota in hypoxic health.

Subtractive proteomics and reverse-vaccinology approaches for novel drug targets and designing a chimeric vaccine against Ruminococcus gnavus strain RJX1120

Mediterraneibacter gnavus, also known as Ruminococcus gnavus, is a Gram-positive anaerobic bacterium that resides in the human gut microbiota. Notably, this bacterium plays dual roles in health and disease. On one side it supports nutrient metabolism essential for bodily functions and on the other it contributes to the development of Inflammatory Bowel Disease (IBD) and other gastrointestinal disorders. R. gnavus strain RJX1120 is an encapsulated strain and has been linked to develop IBD. Despite the advances made on its role in gut homeostasis, limited information is available on strain-specific virulence factors, metabolic pathways, and regulatory mechanisms. The study of such aspects is crucial to make microbiota-targeted therapy and understand its implications in host health. A multi-epitope vaccine against R. gnavus strain RJX1120 was designed using reverse vaccinology-based subtractive proteomics approach. Among the 3,219 proteins identified in the R. gnavus strain RJX1120, two critical virulent and antigenic proteins, a Single-stranded DNA-binding protein SSB (A0A2N5PT08) and Cell division ATP-binding protein FtsE (A0A2N5NK05) were screened and identified as potential targets. The predicted B-cell and T-cell epitopes from these proteins were screened for essential immunological properties such as antigenicity, allergenicity, solubility, MHC binding affinity, and toxicity. Epitopes chosen were cross-linked using suitable spacers and an adjuvant to develop a multi-epitope vaccine. Structural refinement of the construct revealed that 95.7% of the amino acid residues were located in favored regions, indicating a high-quality structural model. Molecular docking analysis demonstrated a robust interaction between the vaccine construct and the human Toll-like receptor 4 (TLR4), with a binding energy of -1277.0 kcal/mol. The results of molecular dynamics simulations further confirmed the stability of the vaccine-receptor complex under physiological conditions. In silico cloning of the vaccine construct yielded a GC content of 48% and a Codon Adaptation Index (CAI) value of 1.0, indicating optimal expression in the host system. These results indicate the possibility of the designed vaccine construct as a candidate for the prevention of R. gnavus-associated diseases. However, experimental validation is required to confirm its immunogenicity and protective efficacy.

Classification of Irritable Bowel Syndrome Using Brain Functional Connectivity Strength and Machine Learning

BACKGROUND

Irritable Bowel Syndrome (IBS) is a prevalent condition characterized by dysregulated brain-gut interactions. Despite its widespread impact, the brain mechanism of IBS remains incompletely understood, and there is a lack of objective diagnostic criteria and biomarkers. This study aims to investigate brain network alterations in IBS patients using the functional connectivity strength (FCS) method and to develop a support vector machine (SVM) classifier for distinguishing IBS patients from healthy controls (HCs).

METHODS

Thirty-one patients with IBS and thirty age and sex-matched HCs were enrolled in this study and underwent resting-state functional magnetic resonance imaging (fMRI) scans. We applied FCS to assess global brain functional connectivity changes in IBS patients. An SVM-based machine - learning approach was then used to evaluate whether the altered FCS regions could serve as fMRI-based markers for classifying IBS patients and HCs.

RESULTS

Compared to the HCs, patients with IBS showed significantly increased FCS in the left medial orbitofrontal cortex (mOFC) and decreased FCS in the bilateral cingulate cortex/precuneus (PCC/Pcu) and middle cingulate cortex (MCC). The machine-learning model achieved a classification accuracy of 91.9% in differentiating IBS patients from HCs.

CONCLUSION

These findings reveal a unique pattern of FCS alterations in brain areas governing pain regulation and emotional processing in IBS patients. The identified abnormal FCS features have the potential to serve as effective biomarkers for IBS classification. This study may contribute to a deeper understanding of the neural mechanisms of IBS and aid in its diagnosis in clinical practice.

Serotonin signaling to regulate energy metabolism: a gut microbiota perspective

Serotonin is one of the most potent gastrointestinal, peripheral, and neuronal signaling molecules and plays a key role in regulating energy metabolism. Accumulating evidence has shown the complex interplay between gut microbiota and host energy metabolism. In this review, we summarize recent findings on the role of gut microbiota in serotonin metabolism and discuss the complicated mechanisms by which serotonin, working in conjunction with the gut microbiota, affects total body energy metabolism in the host. Gut microbiota affects serotonin synthesis, storage, release, transport, and catabolism. In addition, serotonin plays an indispensable role in regulating host energy homeostasis through organ crosstalk and microbe-host communication, particularly with a wide array of serotonergic effects mediated by diverse serotonin receptors with unique tissue specificity. This fresh perspective will help broaden the understanding of serotonergic signaling in modulating energy metabolism, thus shedding light on the design of innovative serotonin-targeting strategies to treat metabolic diseases.

The role of colonic microbiota amino acid metabolism in gut health regulation

The human gut microbiota plays a critical role in maintaining host homeostasis through metabolic activities. Among these, amino acid (AA) metabolism by the microbiota in the large intestine is highly heterogeneous and relevant to host health. Despite increasing interest, microbial AA metabolism remains relatively unexplored. This review highlights recent advances in colonic microbial AA metabolism, including auxotrophies, AA synthesis, and dissimilatory AA metabolites, and their implications in gut health, focusing on major gastrointestinal diseases including colorectal cancer, inflammatory bowel disease, and irritable bowel syndrome.

Construction and validation of machine learning-based predictive model for colorectal polyp recurrence one year after endoscopic mucosal resection

BACKGROUND

Colorectal polyps are precancerous diseases of colorectal cancer. Early detection and resection of colorectal polyps can effectively reduce the mortality of colorectal cancer. Endoscopic mucosal resection (EMR) is a common polypectomy procedure in clinical practice, but it has a high postoperative recurrence rate. Currently, there is no predictive model for the recurrence of colorectal polyps after EMR.

AIM

To construct and validate a machine learning (ML) model for predicting the risk of colorectal polyp recurrence one year after EMR.

METHODS

This study retrospectively collected data from 1694 patients at three medical centers in Xuzhou. Additionally, a total of 166 patients were collected to form a prospective validation set. Feature variable screening was conducted using univariate and multivariate logistic regression analyses, and five ML algorithms were used to construct the predictive models. The optimal models were evaluated based on different performance metrics. Decision curve analysis (DCA) and SHapley Additive exPlanation (SHAP) analysis were performed to assess clinical applicability and predictor importance.

RESULTS

Multivariate logistic regression analysis identified 8 independent risk factors for colorectal polyp recurrence one year after EMR (P < 0.05). Among the models, eXtreme Gradient Boosting (XGBoost) demonstrated the highest area under the curve (AUC) in the training set, internal validation set, and prospective validation set, with AUCs of 0.909 (95%CI: 0.89-0.92), 0.921 (95%CI: 0.90-0.94), and 0.963 (95%CI: 0.94-0.99), respectively. DCA indicated favorable clinical utility for the XGBoost model. SHAP analysis identified smoking history, family history, and age as the top three most important predictors in the model.

CONCLUSION

The XGBoost model has the best predictive performance and can assist clinicians in providing individualized colonoscopy follow-up recommendations.

Emerging Clostridioides difficile ribotypes have divergent metabolic phenotypes

Clostridioides difficile is a gram-positive spore-forming pathogen that commonly causes diarrheal infections in the developed world. Although C. difficile is a genetically diverse species, certain ribotypes are overrepresented in human infections, and it is unclear if metabolic adaptations are essential for the emergence of these epidemic ribotypes. To identify ribotype-specific metabolic differences, we therefore tested carbon substrate utilization by 88 C. difficile isolates and looked for differences in growth between 22 ribotypes. As expected, C. difficile was capable of growing on a variety of carbon substrates. Further, C. difficile strains clustered by phylogenetic relationship and displayed ribotype-specific and clade-specific metabolic capabilities. Surprisingly, we observed that two emerging lineages, ribotypes 023 and 255, have divergent metabolic phenotypes. In addition, although C. difficile Clade 5 is the most evolutionary distant clade and often detected in animals, it displayed robust growth on simple sugars similar to Clades 1-4. Altogether, our results corroborate the generalist metabolic strategy of C. difficile but also demonstrate lineage-specific metabolic capabilities.IMPORTANCEThe gut pathogen Clostridioides difficile utilizes a wide range of carbon sources. Microbial communities can be rationally designed to combat C. difficile by depleting its preferred nutrients in the gut. However, C. difficile is genetically diverse with hundreds of identified ribotypes, and most of its metabolic studies were performed with lab-adapted strains. To identify ribotype-specific metabolic differences, we profiled carbon metabolism by a myriad of C. difficile clinical isolates. While the metabolic capabilities of these isolates clustered by their genetic lineage, we observed surprising metabolic divergence between two emerging lineages. We also found that genetically newer and older clades grew to a similar level on simple sugars, which contrasts with recent findings that newer clades experienced positive selection on genes involved in simple sugar metabolism. Altogether, our results underscore the importance of considering the metabolic diversity of pathogens in the study of their evolution and the rational design of therapeutic interventions.

Research Status and Trends of Gut Microbiota and Intestinal Diseases Based on Bibliometrics

Gut microbiota plays an important role in gut health, and its dysbiosis is closely related to the pathogenesis of various intestinal diseases. The field of gut microbiota and intestinal diseases has not yet been systematically quantified through bibliometric methods. This study conducted bibliometric analysis to delineate the evolution of research on gut microbiota and intestinal diseases. Data were sourced from the Web of Science Core Collection database from 2009 to 2023 and were scientometrically analyzed using CiteSpace. We have found that the number of annual publications has been steadily increasing and showing an upward trend. China and the Chinese Academy of Sciences are the country and institution with the most contributions, respectively. Frontiers in Microbiology and Nutrients are the journals with the most publications, while Plos One and Nature are the journals with the most citations. The field has shifted from focusing on traditional descriptive analysis of gut microbiota composition to exploring the causal relationship between gut microbiota and intestinal diseases. The research hotspots and trends mainly include the correlation between specific intestinal diseases and gut microbiota diversity, the mechanism of gut microbiota involvement in intestinal diseases, the exploration of important gut microbiota related to intestinal diseases, and the relationship between gut microbiota and human gut health. This study provides a comprehensive knowledge map of gut microbiota and intestinal diseases, highlights key research areas, and outlines potential future directions.

Specific microbial ratio in the gut microbiome is associated with multiple sclerosis

Gut microbiota dysbiosis is associated with multiple sclerosis (MS), but the causal relationship between specific gut bacteria and MS pathogenesis remains poorly understood. Therefore, we profiled the stool microbiome of people with MS (PwMS) and healthy controls (HC) using shotgun metagenomic sequencing. PwMS showed a distinct microbiome compared to HC, with Prevotella copri (PC) and Blautia species as drivers of microbial communities in HC and PwMS, respectively. Administration of MS-driving Blautia species (Blautia wexlerae; BW) to mice resulted in increased levels of gut inflammatory markers and altered microbiota with increased capacity to induce proinflammatory cytokines. Utilizing experimental autoimmune encephalomyelitis (EAE), an animal model of MS, we identified a lower gut Bifidobacterium to Akkermansia ratio as a hallmark of the disease. BW-administered mice also showed a lower Bifidobacterium to Akkermansia ratio pre-EAE induction which correlated with increased disease severity post-EAE induction. The importance of the Bifidobacterium to Akkermansia ratio at the species level, lower Bifidobacterium adolescentis to Akkermansia muciniphila (BA:AM), was validated in our MS cohort and a large International Multiple Sclerosis Microbiome Study. Thus, our findings highlight the BA:AM ratio as a potential gut microbial marker in PwMS, opening avenues for microbiome-based diagnosis, prognosis, and therapy in MS.

Microbiota in inflammatory bowel disease: mechanisms of disease and therapeutic opportunities

Perturbations in the intestinal microbiome are strongly linked to the pathogenesis of inflammatory bowel disease (IBD). Bacteria, fungi and viruses all make up part of a complex multi-kingdom community colonizing the gastrointestinal tract, often referred to as the gut microbiome. They can exert various effects on the host that can contribute to an inflammatory state. Advances in screening, multiomics and experimental approaches have revealed insights into host-microbiota interactions in IBD and have identified numerous mechanisms through which the microbiota and its metabolites can exert a major influence on the gastrointestinal tract. Looking into the future, the microbiome and microbiota-associated processes will be likely to provide unparalleled opportunities for novel diagnostic, therapeutic and diet-inspired solutions for the management of IBD through harnessing rationally designed microbial communities, powerful bacterial and fungal metabolites, individually or in combination, to foster intestinal health. In this Review, we examine the current understanding of the cross-kingdom gut microbiome in IBD, focusing on bacterial and fungal components and metabolites. We examine therapeutic and diagnostic opportunities, the microbial metabolism, immunity, neuroimmunology and microbiome-inspired interventions to link mechanisms of disease and identify novel research and therapeutic opportunities for IBD.

Lacidophilin tablets relieve irritable bowel syndrome in rats by regulating gut microbiota dysbiosis and intestinal inflammation

Irritable bowel syndrome (IBS) is a common clinical functional gastrointestinal disease. It has a complex pathophysiological mechanism, in which the imbalance of gut microbiota might play an important role. Lacidophilin tablets (LH) can regulate gut microbiota, but their effect on IBS is unknown. In this study, the IBS model was established by acetic acid enema combined with the constrained stress method, and rats were fed LH for 2 weeks. LH significantly reduced visceral sensitivity and intestinal propulsion rate and improved IBS-induced anxiety and depressive behavior in IBS rats. LH elevated the expression levels of mucin 2, claudin1, and occludin, and ameliorated IBS-induced structural damage to colonic tissues. The gut microbiota analysis revealed that LH altered the structure and composition of the gut microbiota in IBS rats. In addition, LH reduced the expression levels of inflammatory factor-related genes. These results suggest that LH could significantly improve the visceral sensitivity and intestinal motility disorders of IBS rats, relieve anxiety and depression levels, and alleviate the symptoms of IBS rats by regulating gut microbiota and reducing intestinal inflammation.

The role of the gut microbiome in disorders of gut-brain interaction

Disorders of Gut-Brain Interaction (DGBI) are widely prevalent and commonly encountered in gastroenterology practice. While several peripheral and central mechanisms have been implicated in the pathogenesis of DGBI, a recent body of work suggests an important role for the gut microbiome. In this review, we highlight how gut microbiota and their metabolites affect physiologic changes underlying symptoms in DGBI, with a particular focus on their mechanistic influence on GI transit, visceral sensitivity, intestinal barrier function and secretion, and CNS processing. This review emphasizes the complexity of local and distant effects of microbial metabolites on physiological function, influenced by factors such as metabolite concentration, duration of metabolite exposure, receptor location, host genetics, and underlying disease state. Large-scale in vitro work has elucidated interactions between host receptors and the microbial metabolome but there is a need for future research to integrate such preclinical findings with clinical studies. The development of novel, targeted therapeutic strategies for DGBI hinges on a deeper understanding of these metabolite-host interactions, offering exciting possibilities for the future of treatment of DGBI.

Comparative Analysis of Gut Microbiota in Patients with Irritable Bowel Syndrome and Healthy Controls

Background/Objectives: Growing evidence highlights the pivotal role of gut dysbiosis in the pathophysiology of irritable bowel syndrome (IBS). Despite this, the identification of an "IBS microbiota signature" remains elusive, primarily due to the influence of genetic, dietary, and environmental factors. To address these confounding variables, it is critical to perform comparative analyses using a control group derived from the same community as the IBS patients. This study aimed to evaluate and contrast the gut microbiota composition of IBS patients with healthy controls. Methods: We compared the gut microbiota from stool samples of 25 IBS patients diagnosed according to the Rome IV criteria, and 110 healthy subjects without acute or chronic diseases and not on continuous medication. The high-throughput sequencing of the V3-V4 regions of the 16S rRNA gene was conducted for microbiota analysis. Results: The IBS gut microbiota was richer but exhibited lower alpha diversity compared to the control group, suggesting simplification and imbalance. A beta diversity analysis revealed overall compositional differences between the two groups. A heat tree analysis highlighted key IBS-associated changes, including a decrease in Firmicutes, mainly due to Clostridia, and an increase in Bacteroidota, driven by an expansion of Bacteroidales families. Differential expression analyses identified important genera within these taxa like Bacteroides, Faecalibacterium, and Blautia, which could serve as microbiota-based biomarkers for IBS. Conclusions: Our results reveal both statistically and clinically significant differences in gut microbiota composition and diversity between IBS patients and healthy controls from the same community. These findings provide a deeper understanding of how alterations in the gut microbiota may contribute to IBS symptoms, offering new insights into the diagnosis and potential treatments.

Microbiota governs host chenodeoxycholic acid glucuronidation to ameliorate bile acid disorder induced diarrhea

BACKGROUND

Disorder in bile acid (BA) metabolism is known to be an important factor contributing to diarrhea. However, the pathogenesis of BA disorder-induced diarrhea remains unclear.

METHODS

The colonic BA pool and microbiota between health piglets and BA disorder-induced diarrheal piglets were compared. Fecal microbiota transplantation and various cell experiments further indicated that chenodeoxycholic acid (CDCA) metabolic disorder produced CDCA-3β-glucuronide, which is the main cause of BA disorder diarrhea. Non-targeted metabolomics uncovered the inhibition of the BA glucuronidation by Lactobacillus reuteri (L. reuteri) is through deriving indole-3-carbinol (I3C). In vitro, important gene involved in the reduction of BA disorder induced-diarrhea were screened by RNA transcriptomics sequencing, and activation pathway of FXR-SIRT1-LKB1 to alleviate BA disorder diarrhea and P53-mediated apoptosis were proposed in vitro by multifarious siRNA interference, CO-IP, immunofluorescence, and so on, which mechanism was also verified in a variety of mouse models.

RESULTS

Here, we reveal for the first time that core microbiota derived I3C represses gut epithelium glucuronidation, particularly 3β-glucuronic CDCA production, which reaction is mediated by host UDP glucuronosyltransferase family 1 member A4 (UGT1A4) and necessary of BA disorder induced diarrhea. Mechanistically, L. reuteri derived I3C activates aryl hydrocarbon receptor to decrease UGT1A4 transcription and CDCA-3β-glucuronide content, thereby upregulating FXR-SIRT1-LKB1 signal. LKB1 binds with P53 based on protein interaction, ultimately resists to apoptosis and diarrhea. Moreover, I3C assists CDCA to attain the ameliorative effects of FXR activation in BA disorder diarrhea, through reversion of abnormal metabolism pathway, improving the outcomes of CDCA supplement.

CONCLUSION

These findings uncover the crucial interplay between gut epithelial cells and microbes, highlighting UGT1A4-mediated conversion of CDCA-3β-glucuronide as a key target for ameliorating BA disorder-induced diarrhea. Video Abstract.

Gut microbiome and metabolome characteristics of patients with cholesterol gallstones suggest the preventive potential of prebiotics

Cholesterol gallstones (CGS) still lack effective noninvasive treatment. The etiology of experimentally proven cholesterol stones remains underexplored. This cross-sectional study aims to comprehensively evaluate potential biomarkers in patients with gallstones and assess the effects of microbiome-targeted interventions in mice. Microbiome taxonomic profiling was conducted on 191 samples via V3-V4 16S rRNA sequencing. Next, 60 samples (30 age- and sex-matched CGS patients and 30 controls) were selected for metagenomic sequencing and fecal metabolite profiling via liquid chromatography-mass spectrometry. Microbiome and metabolite characterizations were performed to identify potential biomarkers for CGS. Eight-week-old male C57BL/6J mice were given a lithogenic diet for 8 weeks to promote gallstone development. The causal relationship was examined through monocolonization in antibiotics-treated mice. The effects of short-chain fatty acids such as sodium butyrate, sodium acetate (NaA), sodium propionate, and fructooligosaccharides (FOS) on lithogenic diet-induced gallstones were investigated in mice. Gut microbiota and metabolites exhibited distinct characteristics, and selected biomarkers demonstrated good diagnostic performance in distinguishing CGS patients from healthy controls. Multi-omics data indicated associations between CGS and pathways involving butanoate and propanoate metabolism, fatty acid biosynthesis and degradation pathways, taurine and hypotaurine metabolism, and glyoxylate and dicarboxylate metabolism. The incidence of gallstones was significantly higher in the Clostridium glycyrrhizinilyticum group compared to the control group in mice. The grade of experimental gallstones in control mice was significantly higher than in mice treated with NaA and FOS. FOS could completely inhibit the formation of gallstones in mice. This study characterized gut microbiome and metabolome alterations in CGS. C. glycyrrhizinilyticum contributed to gallstone formation in mice. Supplementing with FOS could serve as a potential approach for managing CGS by altering the composition and functionality of gut microbiota.

Metagenomic global survey and in-depth genomic analyses of Ruminococcus gnavus reveal differences across host lifestyle and health status

Ruminococcus gnavus is a gut bacterium found in > 90% of healthy individuals, but its increased abundance is also associated with chronic inflammatory diseases, particularly Crohn's disease. Nevertheless, its global distribution and intraspecies genomic variation remain understudied. By surveying 12,791 gut metagenomes, we recapitulated known associations with metabolic diseases and inflammatory bowel disease. We uncovered a higher prevalence and abundance of R. gnavus in Westernized populations and observed bacterial relative abundances up to 83% in newborns. Next, we built a resource of R. gnavus isolates (N = 45) from healthy individuals and Crohn's disease patients and generated complete R. gnavus genomes using PacBio circular consensus sequencing. Analysis of these genomes and publicly available high-quality draft genomes (N = 333 genomes) revealed multiple clades which separated Crohn's-derived isolates from healthy-derived isolates. Presumed R. gnavus virulence factors could not explain this separation. Bacterial genome-wide association study revealed that Crohn's-derived isolates were enriched in genes related to mobile elements and mucin foraging. Together, we present a large R. gnavus resource that will be available to the scientific community and provide novel biological insights into the global distribution and genomic variation of R. gnavus.

Probiotic administration aggravates dextran sulfate sodium salt-induced inflammation and intestinal epithelium disruption in weaned pig

BACKGROUND

A. muciniphila (AKK) has attracted extensive research interest as a potential next-generation probiotics, but its role in intestinal pathology is remains unclear. Herein, this study was conducted to investigate the effects of A. muciniphila DSM 22,959 on growth performance, intestinal barrier function, microecology and inflammatory response of weaned piglets stimulated by dextran sulfate sodium salt (DSS).

METHOD

Twenty-four Duroc × Landrace × Yorkshire (DLY) weaned piglets used for a 2 × 2 factorial arrangement of treatments were divided into four groups with six piglets in each group. From 1 to 15 d, the CA and DA groups were orally fed with 1.0 × 1011 colony-forming units A. muciniphila per day, while the CON and DCON groups were received gastric infusion of anaerobic sterile saline per day. The pigs were orally challenged (DCON, DA) or not (CON, CA) with DSS from day 9 to the end of the experiment and slaughtered on day 16.

RESULTS

Presence of A. muciniphila in DSS-challenged weaned pigs resulted in numerically increased diarrhea rate, blood neutrophilic granulocyte, serum C-reactive protein and immunoglobulin M levels, and numerically reduced final weight, average daily feed intake and average daily gain. The decrease in intestinal villus height, villous height: crypt depth ratio and digestibility was accompanied by lower expression of ZO1, ZO2, Claudin1, DMT1, CAT1, SGLT1 and PBD114 genes, as well as decreased enzyme activities of intestinal alkaline phosphatase, lactase, sucrase and maltase of piglets in DA group compared to piglets in DCON group. The abundance of Bifdobacterium, Lactobacillus, A. muciniphila, Ruminococcus gnavus was numerically higher in digesta of pigs in DA group than those in DCON group. The inflammatory responses of piglets were dramatically changed by the simultaneous presence of A. muciniphila and DSS: expression level of IL17A, IL17F, IL23, RORγt, Stat3 was elevated in DA pigs compared to the other pig groups.

CONCLUSIONS

Our result showed that the oral A. muciniphila aggravates DSS-induced health damage of weaned piglet, which may attribute to the deteriorating intestinal morphology, dysbiosis of microbiota and inflammatory response disorders.

Timing of standard chow exposure determines the variability of mouse phenotypic outcomes and gut microbiota profile

Standard chow diets influence reproducibility in animal model experiments because chows have different nutrient compositions, which can independently influence phenotypes. However, there is little evidence of the role of timing in the extent of variability caused by chow exposure. Here we measured the impact of different diets (5V5M, 5V0G, 2920X and 5058) and timing of exposure (adult exposure (AE), lifetime exposure (LE) and developmental exposure (DE)) on growth and development, metabolic health indicators and gut bacterial microbiota profiles across genetically identical C57BL/6J mice. Diet drove differences in macro- and micronutrient intake for all exposure models. AE had no effect on phenotypic outcomes. However, LE mice exhibited significant sex-dependent diet effects on growth, body weight and body composition. LE effects were mostly absent in the DE model, where mice were exposed to chow differences only from conception to weaning. Both AE and LE models exhibited similar diet-driven beta diversity profiles for the gut bacterial microbiota, with 5058 diet driving the most distinct profile. However, compared with AE, LE effects on beta diversity were sex dependent, and LE mice exhibited nine times more differentially abundant bacterial genera, the majority of which were inversely affected by 2920X and 5058 diets. Our findings demonstrate that LE to different chow diets has the greatest impact on the reproducibility of several experimental measures commonly used in preclinical mouse model studies. Importantly, weaning mice from different diets onto the same diet for maturation may be an effective way to reduce unwanted phenotypic variability among experimental models.

Adenosine regulates depressive behavior in mice with chronic social defeat stress through gut microbiota

Major depressive disorder (MDD) is recognized as the most prevalent affective disorder worldwide. Metagenomic studies increasingly support a critical role for dysbiosis of gut microbiota in the development of depression. Previous studies have demonstrated that adenosine alleviates gut dysbiosis, suggesting that elevating adenosine levels could be a novel intervention for MDD; however, the mechanisms underlying this effect remain unclear. This study utilized 16S rRNA gene sequencing, fecal microbiota transplantation (FMT) and ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) to test the hypothesis that increased adenosine alleviates depressive behaviors in male mice subjected to chronic social defeat stress (CSDS) through alterations to gut microbiota. The data showed that depression-susceptible (SUS) mice exhibited gut dysbiosis, and FMT from SUS mice increased depression-like behaviors in healthy recipients. In SUS mice, adenosine supplementation ameliorated both depression-like behaviors and abnormalities in gut microbiota, and co-administration of probiotics and adenosine not only mitigated depression-like behaviors but also enhanced gut barrier integrity. By including 83 depressed adolescents and 67 healthy controls, this study found that the level of short-chain fatty acids (SCFAs) in the depression group was reduced, this finding parallels reductions seen in SUS mice and in recipient mice after FMT from SUS donors. Conversely, supplementation with either adenosine or probiotics led increased SCFAs concentrations in the serum of SUS mice. These findings suggest that adenosine may alleviate depression-like behaviors in CSDS mice by modulating the gut microbiota. This effect is likely associated with increased serum SCFAs, metabolites produced by the gut microbiota, following adenosine supplementation. This article is part of the Special Issue on "Personality Disorders".

The Role of Gut Microbiome in Irritable Bowel Syndrome: Implications for Clinical Therapeutics

Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder (FGID) characterized by chronic or recurrent gastrointestinal symptoms without organic changes, and it is also a common disorder of gut-brain interaction (DGBIs).. The symptoms of IBS not only affect the quality of life for individual patients but also place a significant burden on global healthcare systems. The lack of established and universally applicable biomarkers for IBS, along with the substantial variability in symptoms and progression, presents challenges in developing effective clinical treatments. In recent years, preclinical and clinical studies have linked the pathogenesis of IBS to alterations in the composition and function of the intestinal microbiota. Within the complex microbial community of the gut, intricate metabolic and spatial interactions occur among its members and between microbes and their hosts. Amid the multifaceted pathophysiology of IBS, the role of intestinal microenvironment factors in symptom development has become more apparent. This review aims to delve into the changes in the composition and structure of the gut microbiome in individuals with IBS. It explores how diet-mediated alterations in intestinal microbes and their byproducts play a role in regulating the pathogenesis of IBS by influencing the "brain-gut" axis, intestinal barrier function, immune responses, and more. By doing so, this review seeks to lay a theoretical foundation for advancing the development of clinical therapeutics for IBS.

Functional Analysis of TAAR1 Expression in the Intestine Wall and the Effect of Its Gene Knockout on the Gut Microbiota in Mice

Currently, the TAAR1 receptor has been identified in various cell groups in the intestinal wall. It recognizes biogenic amine compounds like phenylethylamine or tyramine, which are products of decarboxylation of phenylalanine and tyrosine by endogenous or bacterial decarboxylases. Since several gut bacteria produce these amines, TAAR1 is suggested to be involved in the interaction between the host and gut microbiota. The purpose of this present study was to clarify the TAAR1 function in the intestinal wall and estimate the TAAR1 gene knockout effect on gut microbiota composition. By analyzing public transcriptomic data of the GEO repository, we identified TAAR1 expression in enterocytes, enteroendocrine cells, tuft cells, and myenteric neurons in mice. The analysis of genes co-expressed with TAAR1 in enteroendocrine cells allows us to suggest the TAAR1 involvement in enteroendocrine cell maturation. Also, in myenteric neurons, we identified the co-expression of TAAR1 with calbindin, which is specific for sensory neurons. The 16S rRNA gene-based analysis of fecal microbiota revealed a slight but significant impact of TAAR1 gene knockout in mice on the gut microbial community, which manifests in the higher diversity, accompanied by low between-sample variability and reorganization of the microbial co-occurrence network.

Saccharomyces cerevisiae and Kluyveromyces marxianus yeast co-cultures modulate the ruminal microbiome and metabolite availability to enhance rumen barrier function and growth performance in weaned lambs

In lambs, weaning imposes stress that can contribute to impaired rumen epithelial barrier functionality and immunological dysregulation. In this study, the effects of a yeast co-culture consisting of Saccharomyces cerevisiae and Kluyveromyces marxianus (NM) on rumen health in lambs was evaluated, with a focus on parameters including growth performance, ruminal fermentation, and epithelial barrier integrity, ruminal metabolic function, and the composition of the ruminal bacteria. In total, 24 lambs were grouped into four groups of six lambs including a control (C) group fed a basal diet, and N, M, and NM groups in which lambs were fed the basal diet respectively supplemented with S. cerevisiae yeast cultures (30 g/d per head), K. marxianus yeast cultures (30 g/d per head), and co-cultures of both yeasts (30 g/d per head), the experiment lasted for 42 d. Subsequent analyses revealed that relative to the C group, the average daily gain (ADG) of lambs in the NM group was significantly greater and exhibited significant increases in a range of mRNA relative expression including monocarboxylate transporter 1 (MCT1), (Na+)/hydrogen (H+) exchanger 1 (NHE1), (Na+)/hydrogen (H+) exchanger 3 (NHE3), proton-coupled amino acid transporter 1 (PAT1), vacuolar H+-ATPase (vH+ ATPase), claudin-1, occludin in the rumen epithelium (P < 0.05). Compared with the C group, the pH of the rumen contents in the NM group was significantly decreased , and the concentrations of acetate, propionate, and butyrate were significantly increased (P < 0.05). Analysis of the rumen bacteria showed that the NM group exhibited increases in the relative abundance of Prevotella, Treponema, Moryella, Fibrobacter, CF231 and Ruminococcus (P < 0.05). Metabolomics analyses revealed an increase in the relative content of phthalic acid and cinnamaldehyde in the NM group as compared to the C group (P < 0.05), together with the greater relative content of L-tyrosine, L-dopa, rosmarinic acid, and tyrosol generated by the tyrosine metabolic pathway (P < 0.05). Spearman's correlation analyses revealed relative abundance levels of Fibrobacter and Ruminococcus were positively correlated with the mRNA relative expression levels of PAT1, NHE3, and zonula occluden-1 (ZO-1), as well as with tyrosol, phthalic acid, and cinnamaldehyde levels (P < 0.05). Ultimately, these results suggest that dietary supplementation with NM has a wide range of beneficial effects on weaned lambs and is superior to single bacterial fermentation. These effects include improvements in daily gain and rumen epithelial barrier integrity, as well as improvements in the composition of the rumen microbiome, and alterations in tyrosine metabolic pathways.

Chinese Herbal Medicine for Irritable Bowel Syndrome: A Perspective of Local Immune Actions

Irritable bowel syndrome (IBS) is the functional gastrointestinal disorder, characterized by abdominal pain and altered bowel habits. The interest in intestinal immune activation as a potential disease mechanism for IBS has increased exponentially in recent years. This study was designed to summarize the Chinese herbal medicine (CHM) that potentially exert protective effects against IBS through inhibition of intestinal immune activation. We detailed the current evidence that immune activation contributes to the pathology of IBS and discussed the potential mechanisms involved. Then, therapeutic effects and possible mechanisms related to immune response of herbal medicine prescriptions, extracts, and monomers were analyzed. The reasons leading to the aberrant and persistent immune activation noted in IBS are mainly associated with the increased number of mast cells, CD3[Formula: see text] T cells, and CD4[Formula: see text] T cells. The mechanisms mainly focused on the gut microbiota disorder induced alteration of the PGE2/COX2/SERT/5-HT, TLR4/MyD88/NF-κB, and BDNF/TrkB pathways. Most of the CHM alleviated IBS through interventions of intestinal immune activation via gut microbiota related to the TLR4/MyD88/NF-κB and SCF/c-kit pathways. We hope this review will provide some clues for the further development of novel candidate agents for IBS and other intestinal immune disorders.

Microbiome Shifts and Their Impact on Gut Physiology in Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is one of the most prevalent functional gastrointestinal disorders characterized by recurrent abdominal pain and altered bowel habits. The exact pathophysiological mechanisms for IBS development are not completely understood. Several factors, including genetic predisposition, environmental and psychological influences, low-grade inflammation, alterations in gastrointestinal motility, and dietary habits, have been implicated in the pathophysiology of the disorder. Additionally, emerging evidence highlights the role of gut microbiota in the pathophysiology of IBS. This review aims to thoroughly investigate how alterations in the gut microbiota impact physiological functions such as the brain-gut axis, immune system activation, mucosal inflammation, gut permeability, and intestinal motility. Our research focuses on the dynamic "microbiome shifts", emphasizing the enrichment or depletion of specific bacterial taxa in IBS and their profound impact on disease progression and pathology. The data indicated that specific bacterial populations are implicated in IBS, including reductions in beneficial species such as Lactobacillus and Bifidobacterium, along with increases in potentially harmful bacteria like Firmicutes and Proteobacteria. Emphasis is placed on the imperative need for further research to delineate the role of specific microbiome alterations and their potential as therapeutic targets, providing new insights into personalized treatments for IBS.

Immunoglobulin-coating patterns reveal altered humoral responses to gut bacteria in pediatric cow milk allergies

BACKGROUND

Pediatric cow milk allergies (CMA) can occur in immunoglobulin (Ig) E and non-IgE-mediated forms. Unlike IgE-mediated allergies, the mechanisms of disease pathogenesis in non-IgE-mediated food allergy and an association with microbiome has not been well established. Previous studies have identified the presence of altered humoral responses to gut bacteria in IgE mediated allergies. Here, we analyzed IgA, IgE and IgG responses to gut bacteria in subjects with either IgE or non-IgE mediated CMA to identify relative proportions of Ig-coated bacteria and characterize unique disease specific microbial signatures.

METHODS

Multi-parametric flow cytometry analysis was used to identify IgA, IgE and IgG responses to gut bacteria in CMA patients. Cell sorting of Ig coated gut bacteria was subsequently performed followed by high throughput 16S rRNA gene sequencing and specific patterns of humoral responses to gut bacteria assessed in each study group.

RESULTS

We identified significant alterations in IgA and IgG gut bacterial coating patterns in CMA subjects. Proportions of IgA-coated bacteria were decreased in IgE mediated CMA subjects without atopic dermatitis (ALL) and non-IgE mediated CMA subjects (ENP), compared to healthy controls (CON). In comparison, IgG-coated bacteria was significantly elevated in CMA subjects with atopic dermatitis (AD). Alpha and beta diversities displayed significant differences in IgA-, IgE-, and IgG-coated bacteria in AD and ENP groups. Significant differences in bacteria coated by IgA, IgE and IgG were detected at Phyla, Genus and Species levels and associated bacterial dysbiosis in IgE and non-IgE mediated allergies were identified. Linear discriminant analysis (LDA) effect size (LEFse) revealed unique disease associated bacterial signatures, including several pathogenic bacteria namely Bacteroides fragilis, Ruminococcus gnavus, Eubacterium dolichum, Fusobacterium, Clostridium neonatale and Robinsoniella peoriensis. Receiver operating characteristic curve analysis confirmed the efficiency of using the bacterial signatures identified as biomarkers for disease.

CONCLUSIONS

Altered IgA and IgG responses to gut bacteria were identified in CMA subjects. The disease-specific responses were associated with alterations in bacterial diversity and concomitant dysbiosis of Ig-coated bacteria in IgE-mediated and non-IgE-mediated CMA pediatric subjects. The identification of pathogenic bacteria uniquely associated with different classes of allergic disease indicates a role of these bacteria in driving disease-specific pathological phenotypes.

Unveiling the therapeutic potential and mechanism of inulin in DSS-induced colitis mice

Inulin has been reported to alleviate colitis. In this study, colitis patients' feces were used to simulate fermentation to demonstrate changes in the microbiota profile in the presence of inulin. We found inulin can reshape the gut microbiota profile of colitis patients, especially by altering the abundance of Faecalibacterium and Blautia. Interestingly, the subsequent co-culture with inulin demonstrated that inulin promoted the growth of these two strains of bacteria. The dextran sodium sulfate (DSS)-induced mouse model was used to examine the effect of inulin and its combination with two probiotics on colitis. Results showed that all three treatments can alleviate the clinical symptoms, including weight-losing, colon-shortening, and the Disease Activity Index (DAI) score. Further investigations showed that the administrations regulate colitis mice's pro- and anti-inflammatory cytokines, such as TNF-α, IL-1β, IL-6, IL-10, and IL-17. Also, they alter the relative abundance of Faecalibacterium and Blautia, change the short-chain fatty acids (SCFAs) profile in the cecum and colon, and improve the intestinal barrier; specifically, the intervention increased the expressions of Claudin, Occludin, Zonula Occludens (ZO)-1, and Mucin (MUC)-2 in colonic tissues, thus restoring the colonic tissue structure and morphology of colitis mice. Collectively, our results confirm that inulin can alter the colitis patients' characteristic microbial community, and they can ameliorate experimental colitis by inhibiting the TRL4/MyD88/NF-κB signaling pathway-improving the inflammatory response and enhancing the intestinal barrier. In conclusion, we propose that inulin may hold promise as a functional food therapeutic approach for the treatment of colitis.

Cross-Cohort Gut Microbiome Signatures of Irritable Bowel Syndrome Presentation and Treatment

Irritable bowel syndrome (IBS) is a prevalent disorder of gut-brain interaction without a reliable cure. Evidence suggests that an alteration of the gut microbiome may contribute to IBS pathogenesis, motivating the development of microbiome-targeted therapies to alleviate IBS symptoms. However, IBS-specific microbiome signatures are variable across cohorts. A total of 9204 datasets were meta-analyzed, derived from fourteen IBS microbiome discovery cohorts, three validation cohorts for diet-microbiome interactions, and five rifaximin therapy cohorts. The consistent bacterial species and functional signatures associated with IBS were identified. Network analysis revealed two distinct IBS-enriched microbiota clusters; obligate anaerobes that are found commonly in the gut, and facultative anaerobes typically present in the mouth, implying a possible association between oral bacterial translocation to gut and IBS pathogenesis. By analyzing diet-microbiome interactions, microbiota-targeted diets that can potentially modulate the altered gut microbiota of IBS subjects toward a healthy status were identified. Furthermore, rifaximin treatment of IBS subjects was linked with a reduction in the abundance of facultatively anaerobic pathobionts. Gut microbiome signatures were identified across IBS cohorts that may inform the development of therapies for microbiome modulation in IBS. The microbiota-targeted diet patterns described may enable nutritional intervention trials in IBS and for assisting dietary management.

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

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

The role of the gut microbiota in neurodegenerative diseases targeting metabolism

In recent years, the incidence of neurodegenerative diseases (NDs) has gradually increased over the past decades due to the rapid aging of the global population. Traditional research has had difficulty explaining the relationship between its etiology and unhealthy lifestyle and diets. Emerging evidence had proved that the pathogenesis of neurodegenerative diseases may be related to changes of the gut microbiota's composition. Metabolism of gut microbiota has insidious and far-reaching effects on neurodegenerative diseases and provides new directions for disease intervention. Here, we delineated the basic relationship between gut microbiota and neurodegenerative diseases, highlighting the metabolism of gut microbiota in neurodegenerative diseases and also focusing on treatments for NDs based on gut microbiota. Our review may provide novel insights for neurodegeneration and approach a broadly applicable basis for the clinical therapies for neurodegenerative diseases.

A New Strategy for Dietary Nutrition to Improve Intestinal Homeostasis in Diarrheal Irritable Bowel Syndrome: A Perspective on Intestinal Flora and Intestinal Epithelial Interaction

BACKGROUND AND OBJECTIVES

Although a reasonable diet is essential for promoting human health, precise nutritional regulation presents a challenge for different physiological conditions. Irritable Bowel Syndrome (IBS) is characterized by recurrent abdominal pain and abnormal bowel habits, and diarrheal IBS (IBS-D) is the most common, seriously affecting patients' quality of life. Therefore, the implementation of precise nutritional interventions for IBS-D has become an urgent challenge in the fields of nutrition and food science. IBS-D intestinal homeostatic imbalance involves intestinal flora disorganization and impaired intestinal epithelial barrier function. A familiar interaction is evident between intestinal flora and intestinal epithelial cells (IECs), which together maintain intestinal homeostasis and health. Dietary patterns, such as the Mediterranean diet, have been shown to regulate gut flora, which in turn improves the body's health by influencing the immune system, the hormonal system, and other metabolic pathways.

METHODS

This review summarized the relationship between intestinal flora, IECs, and IBS-D. It analyzed the mechanism behind IBS-D intestinal homeostatic imbalance by examining the interactions between intestinal flora and IECs, and proposed a precise dietary nutrient intervention strategy.

RESULTS AND CONCLUSION

This increases the understanding of the IBS-D-targeted regulation pathways and provides guidance for designing related nutritional intervention strategies.

Gut microbiota, a key to understanding the knowledge gaps on micro-nanoplastics-related biological effects and biodegradation

Micro-nanoplastics (MNPs) pollution as a global environmental issue has received increasing interest in recent years. MNPs can enter and accumulate in the organisms including human beings mainly via ingestion and inhalation, and large amounts of foodborne MNPs have been frequently detected in human intestinal tracts and fecal samples. MNPs regulate the structure composition and metabolic functions of gut microbiota, which may cause the imbalance of intestinal ecosystems of the hosts and further mediate the occurrence and development of various diseases. In addition, a growing number of MNPs-degrading strains have been isolated from organismal feces. MNPs-degraders colonize the plastic surfaces and form the biofilms, and the long-chain polymers of MNPs can be biologically depolymerized into short chains. In general, MNPs are gradually degraded into small molecule substances (e.g., N2, CH4, H2O, and CO2) via a series of enzymatic catalyses, mainly including biodeterioration, fragmentation, assimilation, and mineralization. In this review, we outline the current progress of MNPs effects on gut microbiota and MNPs degradation by gut microbiota, which provide a certain theoretical basis for fully understanding the knowledge gaps on MNPs-related biological effect and biodegradation.

Da-Jian-Zhong decoction alleviates diarrhea-predominant irritable bowel syndrome via modulation of gut microbiota and Th17/Treg balance

ETHNOPHARMACOLOGICAL RELEVANCE

Da-Jian-Zhong decoction (DJZD) is a herbal formula clinically used for abdominal pain and diarrhea induced by spleen-Yang deficiency syndrome. Recently, treatment of diarrhea-predominant irritable bowel syndrome (IBS-D) with DJZD has received increasing attention, but the underlying mechanism of action remains elusive.

AIM OF THE STUDY

We aimed to evaluate the therapeutic effect of DJZD on IBS-D rats and to elucidate the underlying mechanisms.

MATERIALS AND METHODS

An IBS-D rats model was constructed using a two-factor superposition method of neonatal maternal separation and Senna folium aqueous extract lavage. Moreover, the effect of DJZD was evaluated based on the body weight, rectal temperature, abdominal withdrawal reflex (AWR), and Bristol stool scale score (BSS). The factors that regulate the DJZD effects on IBS-D were estimated using whole microbial genome, transcriptome sequencing (RNA-Seq), flow cytometry, and quantitative reverse transcription polymerase chain reaction (RT-qPCR) analyses.

RESULTS

We found that DJZD alleviated the symptoms of IBS-D rats, with the low-dose (2.4 g/kg) as the better ones, as shown by the higher body weight and lower AWR score and BSS. At the phylum level, the relative abundance of Bacteroidetes was obviously increased, and at the genus level, Lactobacillus and Parabacteroides were increased, while that of Firmicutes_bacterium_424 and Ruminococcus gnavus was decreased in DJZD group. Furthermore, the significantly enriched GO terms after treatment with DJZD mainly included the immune response, positive regulation of activated T cell proliferation, and positive regulation of interleukin-17 (IL-17) production. Importantly, flow cytometry analysis further revealed that the T helper cell type 17/regulatory T cell (Th17/Treg) balance contributed to the DJZD-induced alleviation of IBS-D symptoms, as DJZD downregulated Th17/Treg ratio and Th17 cell-related cytokines IL-17 and IL-6 levels in the colon.

CONCLUSIONS

These results demonstrated that DJZD has a good therapeutic effect on IBS-D rats, probably by maintaining the homeostasis of gut microbiota and regulating Th17/Treg balance and its related inflammatory factors.

The Influence of Intestinal Microbiota on BDNF Levels

The regulation of neurogenesis, the complex process of producing and differentiating new brain tissue cells, is influenced by a complex interaction of internal and external factors. Over the past decade, extensive research has been conducted on neurotrophins and their key role in adult neurogenesis, as well as their impact on diseases such as depression. Among neurotrophins, the brain-derived neurotrophic factor (BDNF) has been the subject of comprehensive studies on adult neurogenesis, and scientific evidence supports its necessity for neurogenesis in the subventricular zone of the hippocampus. A novel area of research is the emerging role of gut microbiota as a significant contributor to neurogenesis and neurotrophin production. Studies have shown that reduced BDNF levels can lead to mood disorders, which are observed in intestinal dysbiosis, characterized by an imbalance in the composition and quantity of the intestinal microbiota. There is evidence in the literature that there is a link between brain function and gut microbiota. Physical activity, and especially the regularity and intensity of exercise, is important in relation to the level of BDNF and the intestinal microbiota. Probiotics, prebiotics and physical activity may have a positive effect on the intestinal microbiota, and therefore also on the level of the brain-derived neurotrophic factor.

Disturbances of the gut microbiota-derived tryptophan metabolites as key actors in vagotomy-induced mastitis in mice

Previous studies have demonstrated that gut microbiota dysbiosis promotes the development of mastitis. The interaction of the vagus nerve and gut microbiota endows host homeostasis and regulates disease development, but whether the vagus nerve participates in the pathogenesis of mastitis is unclear. Here, vagotomized mice exhibit disruption of the blood-milk barrier and mammary gland inflammation. Notably, mastitis and barrier damage caused by vagotomy are dependent on the gut microbiota, as evidenced by antibiotic treatment and fecal microbiota transplantation. Vagotomy significantly alters the gut microbial composition and tryptophan metabolism and reduces the 5-hydroxyindole acetic acid (5-HIAA) level. Supplementation with 5-HIAA alleviates vagotomy-induced mastitis, which is associated with the activation of the aryl hydrocarbon receptor (AhR) and subsequent inhibition of the NF-κB pathway. Collectively, our findings indicate the important role of the vagus-mediated gut-mammary axis in the pathogenesis of mastitis and imply a potential strategy for the treatment of mastitis by targeting the vagus-gut microbiota interaction.

Emerging Clostridioides difficile ribotypes have divergent metabolic phenotypes

Clostridioides difficile is a gram-positive spore-forming pathogen that commonly causes diarrheal infections in the developed world. Although C. difficile is a genetically diverse species, certain ribotypes are overrepresented in human infections. It is unknown if metabolic adaptations are essential for the emergence of these epidemic ribotypes. Here, we tested carbon substrate utilization by 88 C. difficile isolates and looked for differences in growth between 22 ribotypes. By profiling clinical isolates, we assert that C. difficile is a generalist species capable of growing on a variety of carbon substrates. Further, C. difficile strains clustered by phylogenetic relationship and displayed ribotype-specific and clade-specific metabolic capabilities. Surprisingly, we observed that two emerging lineages, ribotypes 023 and 255, have divergent metabolic phenotypes. In addition, although C. difficile Clade 5 is the most evolutionary distant clade and often detected in animals, it displayed more robust growth on simple dietary sugars than Clades 1-4. Altogether, our results corroborate the generalist metabolic strategy of C. difficile and demonstrate lineage-specific metabolic capabilities. In addition, our approach can be adapted to the study of additional pathogens to ascertain their metabolic niches in the gut.

IMPORTANCE

The gut pathogen Clostridioides difficile utilizes a wide range of carbon sources. Microbial communities can be rationally designed to combat C. difficile by depleting its preferred nutrients in the gut. However, C. difficile is genetically diverse with hundreds of identified ribotypes and most of its metabolic studies were performed with lab-adapted strains. Here, we profiled carbon metabolism by a myriad of C. difficile clinical isolates. While the metabolic capabilities of these isolates clustered by their genetic lineage, we observed surprising metabolic divergence between two emerging lineages. We also found that the most genetically distant clade grew robustly on simple dietary sugars, posing intriguing questions about the adaptation of C. difficile to the human gut. Altogether, our results underscore the importance of considering the metabolic diversity of pathogens in the study of their evolution and the rational design of therapeutic interventions.

Mechanisms of intestinal injury in polychaete Perinereis aibuhitensis caused by low-concentration fluorene pollution: Microbiome and metabonomic analyses

The polychaete Perinereis aibuhitensis is used for bioremediation; however, its ability to remove fluorene, a common environmental pollutant, from sediments remains unclear, especially at low concentrations of fluorene (10 mg/kg). In this study, we explored the mechanism of intestinal injury induced by low concentrations of fluorene and the reason intestinal injury is alleviated in high fluorene concentration groups (100 and 1000 mg/kg) using histology, ecological biomarkers, gut microbiome, and metabolic response analyses. The results show that P. aibuhitensis showed high tolerance to fluorene in sediments, with clearance rates ranging 25-50 %. However, the remediation effect at low fluorene concentrations (10 mg/kg) was poor. This is attributed to promoting the growth of harmful microorganisms such as Microvirga, which can cause metabolic disorders, intestinal flora imbalances, and the generation of harmful substances such as 2-hydroxyfluorene. These can result in severe intestinal injury in P. aibuhitensis, reducing its fluorene clearance rate. However, high fluorene concentrations (100 and 1000 mg/kg) may promote the growth of beneficial microorganisms such as Faecalibacterium, which can replace the dominant harmful microorganisms and improve metabolism to reverse the intestinal injury caused by low fluorene concentrations, ultimately restoring the fluorene-removal ability of P. aibuhitensis. This study demonstrates an effective method for evaluating the potential ecological risks of fluorene pollution in marine sediments and provides guidance for using P. aibuhitensis for remediation.

Microbiota-Short Chain Fatty Acid Relationships Underlie Clinical Heterogeneity and Identify Key Microbial Targets in Irritable Bowel Syndrome (IBS)

Background

Identifying microbial targets in irritable bowel syndrome (IBS) and other disorders of gut-brain interaction (DGBI) is challenging due to the dynamic nature of microbiota-metabolite-host interactions. SCFA are key microbial metabolites that modulate intestinal homeostasis and may influence IBS pathophysiology. We aimed to assess microbial features associated with short chain fatty acids (SCFA) and determine if features varied across IBS subtypes and endophenotypes. Among 96 participants who were screened, 71 completed the study. We conducted in-depth investigations of stool microbial metagenomes, stool SCFA, and measurable IBS traits (stool bile acids, colonic transit, stool form) in 41 patients with IBS (IBS with constipation [IBS-C] IBS with diarrhea [IBS-D]) and 17 healthy controls. We used partial canonical correspondence analyses (pCCA), conditioned on transit, to quantify microbe-SCFA associations across clinical groups. To explore relationships between microbially-derived SCFA and IBS traits, we compared gut microbiome-encoded potential for substrate utilization across groups and within a subset of participants selected by their stool characteristics as well as stool microbiomes of patients with and without clinical bile acid malabsorption.

Results

Overall stool microbiome composition and individual taxa abundances differed between clinical groups. Microbes-SCFA associations differed across groups and revealed key taxa including Dorea sp. CAG:317 and Bifidobacterium pseudocatenulatum in IBS-D and Akkermansia muciniphila and Prevotella copri in IBS-C that that may drive subtype-specific microbially-mediated mechanisms. Strongest microbe-SCFA associations were observed in IBS-D and several SCFA-producing species surprisingly demonstrated inverse correlations with SCFA. Fewer bacterial taxa were associated with acetate to butyrate ratios in IBS compared to health. In participants selected by stool form, we demonstrated differential abundances of microbial genes/pathways for SCFA metabolism and degradation of carbohydrates and mucin across groups. SCFA-producing taxa were reduced in IBS-D patients with BAM.

Conclusion

Keystone taxa responsible for SCFA production differ according to IBS subtype and traits and the IBS microbiome is characterized by reduced functional redundancy. Differences in microbial substrate preferences are also linked to bowel functions. Focusing on taxa that drive SCFA profiles and stool form may be a rational strategy for identifying relevant microbial targets in IBS and other DGBI.

Association between environmental phthalates exposure and gut microbiota and metabolome in dementia with Lewy bodies

BACKGROUND

Emerging evidence has shown the potential involvement of phthalates (PAEs) exposure in the development of dementia with Lewy bodies (DLB). Metabolomics can reflect endogenous metabolites variation in the progress of disease after chemicals exposure. However, little is known about the association between PAEs, gut microbiota and metabolome in DLB.

OBJECTIVE

We aim to explore the intricate relationship among urinary PAEs metabolites (mPAEs), dysbiosis of gut bacteria, and metabolite profiles in DLB.

METHODS

A total of 43 DLB patients and 45 normal subjects were included in this study. Liquid chromatography was used to analyze the levels of mPAEs in the urine of the two populations. High-throughput sequencing and liquid chromatography-mass spectrometry were used to analyze gut microbiota and the profile of gut metabolome, respectively. The fecal microbiota transplantation (FMT) experiment was performed to verify the potential role of mPAEs on gut dysbiosis contribute to aggravating cognitive dysfunction in α-synuclein tg DLB/PD mice.

RESULTS

The DLB patients had higher DEHP metabolites (MEOHP, MEHHP and MEHP), MMP and MnBP, lower MBP and MBzP than the control group and different microbiota. A significantly higher abundance of Ruminococcus gnavus and lower Prevotella copri, Prevotella stercorea and Bifidobacterium were observed in DLB. Higher 3 DEHP metabolites, MMP, MnBP and lower MBP and MBzP were significantly negatively associated with Prevotella copri, Prevotella stercorea and Bifidobacterium. Additionally, using metabolomics, we found that altered bile acids, short-chain fatty acids and amino acids metabolism are linked to these mPAEs. We further found that FMT of fecal microbiota from highest DEHP metabolites donors significantly impaired cognitive function in the germ-free DLB/PD mice.

CONCLUSION

Our study suggested that PAEs exposure may alter the microbiota-gut-brain axis and providing novel insights into the interactions among environmental perturbations and microbiome-host in pathogenesis of DLB.

Desulfovibrio vulgaris caused gut inflammation and aggravated DSS-induced colitis in C57BL/6 mice model

BACKGROUND

Sulfate-reducing bacteria (SRB) is a potential pathogen usually detected in patients with gastrointestinal diseases. Hydrogen sulfide (H2S), a metabolic byproduct of SRB, was considered the main causative agent that disrupted the morphology and function of gut epithelial cells. Associated study also showed that flagellin from Desulfovibrio vulgaris (DVF), the representative bacterium of the Desulfovibrio genus, could exacerbate colitis due to the interaction of DVF and LRRC19, leading to the secretion of pro-inflammatory cytokines. However, we still have limited understanding about the change of gut microbiota (GM) composition caused by overgrowth of SRB and its exacerbating effects on colitis.

RESULTS

In this study, we transplanted D. vulgaris into the mice treated with or without DSS, and set a one-week recovery period to investigate the impact of D. vulgaris on the mice model. The outcomes showed that transplanted D. vulgaris into the normal mice could cause the gut inflammation, disrupt gut barrier and reduce the level of short-chain fatty acids (SCFAs). Moreover, D. vulgaris also significantly augmented DSS-induced colitis by exacerbating the damage of gut barrier and the secretion of inflammatory cytokines, for instance, IL-1β, iNOS, and TNF-α. Furthermore, results also showed that D. vulgaris could markedly change GM composition, especially decrease the relative abundance of SCFAs-producing bacteria. Additionally, D. vulgaris significantly stimulated the growth of Akkermansia muciniphila probably via its metabolic byproduct, H2S, in vivo.

CONCLUSIONS

Collectively, this study indicated that transplantation of D. vulgaris could cause gut inflammation and aggravate the colitis induced by DSS.

Dopamine Receptors and TAAR1 Functional Interaction Patterns in the Duodenum Are Impaired in Gastrointestinal Disorders

Currently, there is a growing amount of evidence for the involvement of dopamine receptors and the functionally related trace amine-associated receptor, TAAR1, in upper intestinal function. In the present study, we analyzed their expression in the duodenum using publicly accessible transcriptomic data. We revealed the expression of DRD1, DRD2, DRD4, DRD5, and TAAR1 genes in different available datasets. The results of the gene ontology (GO) enrichment analysis for DRD2 and especially TAAR1 co-expressed genes were consistent with the previously described localization of D2 and TAAR1 in enteric neurons and secretory cells, respectively. Considering that co-expressed genes are more likely to be involved in the same biological processes, we analyzed genes that are co-expressed with TAAR1, DRD2, DRD4, and DRD5 genes in healthy mucosa and duodenal samples from patients with functional dyspepsia (FD) or diabetes-associated gastrointestinal symptoms. Both pathological conditions showed a deregulation of co-expression patterns, with a high discrepancy between DRDs and TAAR1 co-expressed gene sets in normal tissues and patients' samples and a loss of these genes' functional similarity. Meanwhile, we discovered specific changes in co-expression patterns that may suggest the involvement of TAAR1 and D5 receptors in pathologic or compensatory processes in FD or diabetes accordingly. Despite our findings suggesting the possible role of TAAR1 and dopamine receptors in functional diseases of the upper intestine, underlying mechanisms need experimental exploration and validation.

Forces Bless You: Mechanosensitive Piezo Channels in Gastrointestinal Physiology and Pathology

The gastrointestinal (GI) tract is an organ actively involved in mechanical processes, where it detects forces via a mechanosensation mechanism. Mechanosensation relies on specialized cells termed mechanoreceptors, which convert mechanical forces into electrochemical signals via mechanosensors. The mechanosensitive Piezo1 and Piezo2 are widely expressed in various mechanosensitive cells that respond to GI mechanical forces by altering transmembrane ionic currents, such as epithelial cells, enterochromaffin cells, and intrinsic and extrinsic enteric neurons. This review highlights recent research advances on mechanosensitive Piezo channels in GI physiology and pathology. Specifically, the latest insights on the role of Piezo channels in the intestinal barrier, GI motility, and intestinal mechanosensation are summarized. Additionally, an overview of Piezo channels in the pathogenesis of GI disorders, including irritable bowel syndrome, inflammatory bowel disease, and GI cancers, is provided. Overall, the presence of mechanosensitive Piezo channels offers a promising new perspective for the treatment of various GI disorders.