Bacteroides thetaiotaomicron relieves colon inflammation by activating aryl hydrocarbon receptor and modulating CD4+T cell homeostasis

Effect of Bacteroides on Crohn's disease

Crohn's disease (CD), also known as cicatrizing enteritis, is an inflammatory bowel disease that occurs in the distal ileum and right colon of unknown cause and is also called inflammatory bowel disease (IBD) with ulcerative colitis (UC). In recent years, intestinal biota have been confirmed to play a significant role in various gastrointestinal diseases. Studies have found that intestinal microbiota disorders are closely associated with the onset and progression of Crohn's disease. Bacteroidetes, the second largest microbiota in the intestine, are crucial for equilibrium in the microbiota and intestinal environment. Certain Bacteroides can induce the development of Crohn's disease and aggravate intestinal inflammation directly or through their metabolites. Conversely, certain Bacteroides can reduce intestinal inflammation and symptoms of Crohn's disease. This article reviews the effect of several intestinal Bacteroides in the onset and progression of Crohn's disease and their impact on its treatment.

Targeting CD4+ T cells through gut microbiota: therapeutic potential of traditional Chinese medicine in inflammatory bowel disease

Inflammatory Bowel Disease (IBD) is an autoimmune disease characterized by chronic relapsing inflammation of the intestinal tract. Gut microbiota (GM) and CD4+T cells are important in the development of IBD. A lot of studies have shown that GM and their metabolites like short-chain fatty acids, bile acids and tryptophan can be involved in the differentiation of CD4+T cells through various mechanisms, which in turn regulate the immune homeostasis of the IBD patients. Therefore, regulating CD4+T cells through GM may be a potential therapeutic direction for the treatment of IBD. Many studies have shown that Traditional Chinese Medicine (TCM) formulas and some herbal extracts can affect CD4+T cell differentiation by regulating GM and its metabolites. In this review, we mainly focus on the role of GM and their metabolites in regulating the differentiation of CD4+T cells and their correlation with IBD. We also summarize the current research progress on the regulation of this process by TCM.

Comparative Analysis of the Skin Microbiota of Rosacea, Steroid-Induced Rosacea and Perioral Dermatitis

Rosacea, steroid-induced rosacea, also known as corticosteroid-induced rosacea-like dermatitis, and perioral dermatitis cause erythema, red papules, and pustules on the face. Tetracycline therapy is often effective for these skin diseases, suggesting that skin bacteria may be involved in these pathogeneses. To explore the etiologic significance of skin bacteria, we examined the microbiota of rosacea, steroid-induced rosacea, and perioral dermatitis, as well as healthy participants (n = 50), using swab specimens that were obtained by rubbing the skin surface and vellus hair specimens that were collected from the perioral lesions. Skin microbiota was determined with short-amplicon sequence analysis for 16S rRNA gene (V1-V2 regions). Comparative analysis of the microbiota showed that the bacterial composition in perioral dermatitis cases was clearly different from that of rosacea cases and healthy participants but similar to that of some cases of steroid-induced rosacea. The uncultured Neisseriales bacterium was prevalent in the skin microbiota of some cases of steroid-induced rosacea and perioral dermatitis cases. After antibiotic therapy to steroid-induced rosacea and perioral dermatitis cases, the uncultured Neisseriales bacterium disappeared with improvement of the skin rash. These results indicate that the skin bacteria involving unculturable bacterium in the skin microbiota had a significant impact on steroid-induced rosacea and perioral dermatitis pathogeneses, and that microbiota-targeted treatment may be effective for steroid-induced rosacea and perioral dermatitis.

Gut microbiota is associated with persistence of longer-term BNT162b2 vaccine immunogenicity

Introduction

BNT162b2 immunogenicity wanes with time and we investigated association between gut microbiota and longer-term immunogenicity.

Methods

This cohort study prospectively recruited adult BNT162b2 two-dose recipients from three vaccination centers in Hong Kong. Blood samples were collected at baseline and day 180 after first dose, and tested for neutralizing antibodies (NAb) against receptor-binding domain (RBD) of wild type SARS-CoV-2 virus using chemiluminescence immunoassay. Shotgun DNA metagenomic sequencing was performed to characterize baseline stool microbiome. Baseline metabolites were measured by gas and liquid chromatography-tandem mass spectrometry (GC-MS/MS and LC-MS/MS). Primary outcome was persistent high NAb response (defined as top 25% of NAb level) at day 180. Putative bacterial species and metabolic pathways were identified using linear discriminant analysis [LDA] effect size analysis. Multivariable logistic regression adjusting for clinical factors was used to derive adjusted odds ratio (aOR) of outcome with bacterial species and metabolites.

Results

Of 242 subjects (median age: 50.2 years [IQR:42.5-55.6]; male:85 [35.1%]), 61 (25.2%) were high-responders while 33 (13.6%) were extreme-high responders (defined as NAb≥200AU/mL). None had COVID-19 at end of study. Ruminococcus bicirculans (log10LDA score=3.65), Parasutterella excrementihominis (score=2.82) and Streptococcus salivarius (score=2.31) were enriched in high-responders, while Bacteroides thetaiotaomicron was enriched in low-responders (score=-3.70). On multivariable analysis, bacterial species (R. bicirculans-aOR: 1.87, 95% CI: 1.02-3.51; P. excrementihominis-aOR: 2.2, 95% CI: 1.18-4.18; S. salivarius-aOR: 2.09, 95% CI: 1.13-3.94) but not clinical factors associated with high response. R. bicirculans positively correlated with most metabolic pathways enriched in high-responders, including superpathway of L-cysteine biosynthesis (score=2.25) and L-isoleucine biosynthesis I pathway (score=2.16) known to benefit immune system. Baseline serum butyrate (aOR:10.00, 95% CI:1.81-107.2) and isoleucine (aOR:1.17, 95% CI:1.04-1.35) significantly associated with extreme-high vaccine response.

Conclusion

Certain gut bacterial species, metabolic pathways and metabolites associate with longer-term COVID-19 vaccine immunogenicity.

Microbiota and metabolomic profiling coupled with machine learning to identify biomarkers and drug targets in nasopharyngeal carcinoma

Background

Nasopharyngeal carcinoma (NPC) is a prevalent malignancy in certain regions, with radiotherapy as the standard treatment. However, resistance to radiotherapy remains a critical challenge, necessitating the identification of novel biomarkers and therapeutic targets. The tumor-associated microbiota and metabolites have emerged as potential modulators of radiotherapy outcomes.

Methods

This study included 22 NPC patients stratified into radiotherapy-responsive (R, n = 12) and radiotherapy-non-responsive (NR, n = 10) groups. Tumor tissue and fecal samples were subjected to 16S rRNA sequencing to profile microbiota composition and targeted metabolomics to quantify short-chain fatty acids (SCFAs). The XGBoost algorithm was applied to identify microbial taxa associated with radiotherapy response, and quantitative PCR (qPCR) was used to validate key findings. Statistical analyses were conducted to assess differences in microbial diversity, relative abundance, and metabolite levels between the groups.

Results

Significant differences in alpha diversity at the species level were observed between the R and NR groups. Bacteroides acidifaciens was enriched in the NR group, while Propionibacterium acnes and Clostridium magna were more abundant in the R group. Machine learning identified Acidosoma, Propionibacterium acnes, and Clostridium magna as key predictors of radiotherapy response. Metabolomic profiling revealed elevated acetate levels in the NR group, implicating its role in tumor growth and immune evasion. Validation via qPCR confirmed the differential abundance of these microbial taxa in both tumor tissue and fecal samples.

Discussion

Our findings highlight the interplay between microbiota and metabolite profiles in influencing radiotherapy outcomes in NPC. These results suggest that targeting the microbiota-metabolite axis may enhance radiotherapy efficacy in NPC.

The mechanism of action of indole-3-propionic acid on bone metabolism

Indole-3-propionic acid (IPA), a metabolite produced by gut microbiota through tryptophan metabolism, has recently been identified as playing a pivotal role in bone metabolism. IPA promotes osteoblast differentiation by upregulating mitochondrial transcription factor A (Tfam), contributing to increased bone density and supporting bone repair. Simultaneously, it inhibits the formation and activity of osteoclasts, reducing bone resorption, possibly through modulation of the nuclear factor-κB (NF-κB) pathway and downregulation of osteoclast-associated factors, thereby maintaining bone structural integrity. Additionally, IPA provides indirect protection to bone health by regulating host immune responses and inflammation via activation of receptors such as the Aryl hydrocarbon Receptor (AhR) and the Pregnane X Receptor (PXR). This review summarizes the roles and signaling pathways of IPA in bone metabolism and its impact on various bone metabolic disorders. Furthermore, we discuss the therapeutic potential and limitations of IPA in treating bone metabolic diseases, aiming to offer novel strategies for clinical management.

Restoring the Multiple Sclerosis Associated Imbalance of Gut Indole Metabolites Promotes Remyelination and Suppresses Neuroinflammation

In multiple sclerosis (MS) the circulating metabolome is dysregulated, with indole lactate (ILA) being one of the most significantly reduced metabolites. We demonstrate that oral supplementation of ILA impacts key MS disease processes in two preclinical models. ILA reduces neuroinflammation by dampening immune cell activation as well as infiltration; and promotes remyelination and in vitro oligodendrocyte differentiation through the aryl hydrocarbon receptor (AhR). Supplementation of ILA, a reductive indole metabolite, restores the gut microbiome's oxidative/reductive metabolic balance by lowering circulating indole acetate (IAA), an oxidative indole metabolite, that blocks remyelination and oligodendrocyte maturation. The ILA-induced reduction in circulating IAA is linked to changes in IAA-producing gut microbiota taxa and pathways that are also dysregulated in MS. Notably, a lower ILA:IAA ratio correlates with worse MS outcomes. Overall, these findings identify ILA as a potential anti-inflammatory remyelinating agent and provide insights into the role of gut dysbiosis-related metabolic alterations in MS progression.

Gut microbiota contributes to the intestinal and extraintestinal immune homeostasis by balancing Th17/Treg cells

Gut microbiota is generally considered to play an important role in host health due to its extensive immunomodulatory activities. Th17 and Treg cells are two important CD4+ T cell subsets involved in immune regulation, and their imbalance is closely tied to many immune diseases. Recently, abundant researches have highlighted the importance of gut microbiota in supporting intestinal and extraintestinal immunity through the balance of Th17 and Treg cells. Here, we presented a comprehensive review of these findings. This review first provided an overview of gut microbiota, along with Th17/Treg cell differentiation and cytokine production. Subsequently, the review summarized the regulatory effects of gut microbiota (in terms of species, components, and metabolites) on the Th17/Treg cell balance in the local intestines and extraintestinal organs, such as lung, liver, brain, kidney, and bone. Specifically, the Th17 and Treg cells that can be modulated by gut microbiota originate not only from the gut and extraintestinal organs, but also from peripheral blood and spleen. Then, the microbial therapeutics, including probiotics, prebiotics, postbiotics, and fecal microbiota transplantation (FMT), were also reviewed because of their therapeutic potentials in addressing intestinal and extraintestinal diseases via the Th17/Treg axis. Finally, the review discussed the clinical applications and future study prospects of microbial therapeutics by targeting the Th17/Treg cell balance. In conclusion, this review focused on elucidating the regulatory effects of gut microbiota in balancing Th17/Treg cells to maintain intestinal and extraintestinal immune homeostasis, contributing to the further development and promotion of microbial therapeutics.

A disturbed metabolite-GPCR axis is associated with microbial dysbiosis in IBD patients: Potential role of GPR109A in macrophages

Inflammatory Bowel Disease (IBD) is a chronic inflammatory disorder of the gastrointestinal tract characterized by disrupted immune function. Indeed, gut microbiota dysbiosis and metabolomic profile alterations, are hallmarks of IBD. In this scenario, metabolite-sensing G-protein coupled receptors (GPCRs), involved in several biological processes, have emerged as pivotal players in the pathophysiology of IBD. The aim of this study was to characterize the axis microbiota-metabolite-GPCR in intestinal surgical resections from IBD patients. Results showed that UC patients had a lower microbiota richness and bacterial load, with a higher proportion of the genus Cellulosimicrobium and a reduced proportion of Escherichia, whereas CD patients showed a decreased abundance of Enterococcus. Furthermore, metabolomic analysis revealed alterations in carboxylic acids, fatty acids, and amino acids in UC and CD samples. These patients also exhibited upregulated expression of most metabolite-sensing GPCRs analysed, which positively correlated with pro-inflammatory and pro-fibrotic markers. The role of GPR109A was studied in depth and increased expression of this receptor was detected in epithelial cells and cells from lamina propria, including CD68+ macrophages, in IBD patients. The treatment with β-hydroxybutyrate increased gene expression of GPR109A, CD86, IL1B and NOS2 in U937-derived macrophages. Besides, when GPR109A was transiently silenced, the mRNA expression and secretion of IL-1β, IL-6 and TNF-α were impaired in M1 macrophages. Finally, the secretome from siGPR109A M1 macrophages reduced the gene and protein expression of COL1A1 and COL3A1 in intestinal fibroblasts. A better understanding of metabolite-sensing GPCRs, such as GPR109A, could establish their potential as therapeutic targets for managing IBD.

Structural characterization, antioxidant activity, and fermentation characteristics of Flammulina velutipes residue polysaccharide degraded by ultrasonic assisted H2O2-Vc technique

Adhere to the concept of low-carbon environmental protection and turning waste into treasure, polysaccharides from Flammulina velutipes residue polysaccharide (FVRP) has been developed and possesses diverse bioactivities, comprising antioxidant, hypoglycemic, and relieving heavy metal damage, which still has the disadvantages of high molecular weight and low bioavailability. The current work is the first to prepare a degraded polysaccharide (FVRPV) from FVRP by ultrasonic assisted H2O2-Vc technique in order to reduce its molecular weight, thereby improving its activity and bioavailability. Our results found that the molecular weight and average particle size were declined, but the monosaccharide composition and characteristic functional group types of FVRPV had no impact. The structural changes of polysaccharides analyzed by XRD, Congo Red test, I2-KI, SEM, and methylation analysis indicated that the surface morphology and glycosidic bond composition of FVRPV possessed longer side chains and a greater number of branches with an amorphous crystal structure devoid of a triple helix configuration, and had experienced notable alterations after ultrasonic assisted H2O2-Vc treatment. Meanwhile, the in vitro antioxidant capacity of FVRPV had significantly increased compared to FVRP, implying ultrasonic assisted H2O2-Vc technique maybe a effective method to enhance the bioactivity of polysaccharides. In addition, the content of polysaccharide, reducing sugar, and uronic acid in FVRPV was significantly decreased, but antioxidant capacity of fermentation broth was stronger by in vitro human fecal fermentation. The 16S rDNA sequencing data displayed that FVRPV can enrich probiotics and reduce the abundance of pathogenic bacteria through different metabolic pathways mediated by gut microbiota, thereby exerting its potential probiotic effects. The interesting work provides a novel degraded polysaccharide by ultrasonic assisted H2O2-Vc technique, laying a foundation for developing FVRPV as a new antioxidant and prebiotic.

Endoplasmic reticulum stress in intestinal microecology: A controller of antineoplastic drug-related cardiovascular toxicity

Endoplasmic reticulum (ER) stress is extensively studied as a pivotal role in the pathological processes associated with intestinal microecology. In antineoplastic drug treatments, ER stress is implicated in altering the permeability of the mechanical barrier, depleting the chemical barrier, causing dysbiosis, exacerbating immune responses and inflammation in the immune barrier. Enteric dysbiosis and intestinal dysfunction significantly affect the circulatory system in various heart disorders. In antineoplastic drug-related cardiovascular (CV) toxicity, ER stress constitutes a web of relationships in the host-microbiome symbiotic regulatory loop. Therefore, understanding the holobiont perspective will help de-escalate spatial and temporal restrictions. This review investigates the role of ER stress-mediated gut microecological alterations in antineoplastic treatment-induced CV toxicity.

Maternal probiotic mixture supplementation optimizes the gut microbiota structure of offspring piglets through the gut-breast axis

Delivery and weaning are major stressful events in sows and piglets, adversely affecting production and growth performance and causing economic losses to swine farms. Probiotics as safe antibiotic alternatives have great potential for use across all stages of livestock farming. Here, 18 pregnant sows from clinical farms randomly were divided into two groups: one fed a basal diet (CON group) and the other fed a basal diet plus a probiotic mixture CBB-mix (containing 1×1012 CFU/g of Lactobacillus johnsonii [CJ21], 1×109 CFU/g of Bacillus subtilis [BS15], and 1×109 CFU/g of Bacillus licheniformis [BL21]), for 20 days before delivery. The effects of maternal CBB-mix supplementation on sow colostrum metabolome and offspring piglets' clinical performance, immune status, and gut microbiota were investigated. Additionally, 177 piglets were randomly divided into 4 groups, including CC group (piglets and sows fed a basal diet, n = 40 from 5 litters), CP group (piglets fed the basal diet plus CBB-mix and sows fed the basal diet, n = 38 from 4 litters), PC group (piglets fed the basal diet and sows fed the basal diet plus CBB-mix, n = 50 from 4 litters), and PP group (both piglets and sows fed the basal diet plus CBB-mix, n = 49 from 5 litters). Among that, CP and PP groups were added CBB-mix in the creep feed from 11 days of age for 18 days to study the direct effects of CBB-mix on the growth performance of piglets. Maternal CBB-mix supplementation improved sow production performance, including litter size at birth and litter weight at birth (P < 0.05). Piglets born from CBB-mix-fed sows exhibited increased litter size at weaning and reduced diarrhea incidence from 1 to 10 days of age (P < 0.05). Additionally, systemic immune status and antioxidant capabilities were improved in both sows and piglets. Maternal CBB-mix supplementation reconstituted the gut microbiota structure and increased the Sobs index and Shannon index of fecal microbiota in both sows and piglets (P < 0.05). The relative abundance of Firmicutes and Clostridium_sensu_stricro_1 in sow feces was decreased after feeding CBB-mix (P < 0.05). In piglets, 10-day-old feces had relatively more Lactobacillus but less Escherichia-Shigella than 1-day-old feces (P < 0.05), indicating that maternal feeding CBB-mix alone affects the gut microbiota community of offspring piglets via the gut-breast axis. Piglets born from CBB-mix-fed sows had continuously decreased the relative abundance of fecal Escherichia-Shigella at 28 days of age (P < 0.05). Consistently, the metabolite profile in sow milk was also changed by CBB-mix. Colostrum metabolome showed that CBB-mix significantly regulated tryptophan metabolism and primary bile acid biosynthesis. Our data demonstrated that maternal CBB-mix supplementation effectively improved the production performance of sows and their offsprings' growth performance. Through the gut-breast axis (interaction between gut microbiota and mammary glands), feeding CBB-mix to sows impacted the gut microbiota of their offspring. This study provides strategy and evidence for maternal probiotic supplementation to improve immune status and gut microbiota homeostasis in response to delivery and weaning.

Effect of Probiotics on Gastrointestinal Health Through the Aryl Hydrocarbon Receptor Pathway: A Systematic Review

Probiotics are living microorganisms recognized for conferring health benefits on the host by modulating the gut microbiota. They interact with various signaling pathways, including the aryl hydrocarbon receptor (AhR), which plays a crucial role in maintaining intestinal homeostasis and immune function. The activation of AhR by probiotics has been associated with benefits such as improved intestinal barrier function, reduced inflammation, and modulation of immune responses. This systematic review aims to summarize current knowledge on the signaling of AhR, mediated by probiotics in physiological conditions and gastrointestinal pathologies. We conducted a comprehensive search across databases, including PubMed and Embase, up until July 2024. Out of 163 studies screened, 18 met the inclusion criteria. Our findings revealed in healthy populations that probiotic consumption increases the production of AhR ligands promoting intestinal immune tolerance. Furthermore, in populations with gastrointestinal pathologies, probiotics ameliorated symptoms through AhR activation by Trp metabolites, leading to the upregulation of the anti-inflammatory response.

Polysaccharides to postbiotics: Nurturing bone health via modulating "gut-immune axis"

The increasing prevalence of individuals affected by bone pathologies globally has sparked catastrophic concerns. Ankylosing spondylitis, osteoporosis, rheumatoid arthritis, osteoarthritis, and fractures alone impact an estimated 1.71 billion people worldwide. The gut microbiota plays a crucial role in interacting with the host through the synthesis of a diverse range of metabolites called gut-associated metabolites (GAMs), which originate from external dietary substrates or endogenous host compounds. Many metabolic disorders have been linked to alterations in the gut microbiota's activity and composition. The development of metabolic illnesses has been linked to certain microbiota-derived metabolites, such as branched-chain amino acids, bile acids, short-chain fatty acids, tryptophan, trimethylamine N-oxide, and indole derivatives. Moreover, the modulation of gut microbiota through biotics (prebiotics, probiotics and postbiotics) presents a promising avenue for therapeutic intervention. Biotics selectively promote the growth of beneficial gut bacteria, thereby enhancing the production of GAMs with potential beneficial effects on bone metabolism. Understanding the intricate interplay between GAMs, and bone-associated genes through molecular informatics holds significant promise for early diagnosis, prognosis, and novel treatment strategies for various bone disorders.

Exogenous MSC based tissue regeneration: a review of immuno-protection strategies from biomaterial scaffolds

Mesenchymal stem cell (MSC)-based tissue engineering holds great potential for regenerative medicine as a means of replacing damaged or lost tissues to restore their structure and function. However, the efficacy of MSC-based regeneration is frequently limited by the low survival rate and limited survival time of transplanted MSCs. Despite the inherent immune privileges of MSCs, such as low expression of major histocompatibility complex antigens, tolerogenic properties, local immunosuppressive microenvironment creation, and induction of immune tolerance, immune rejection remains a major obstacle to their survival and regenerative potential. Evidence suggests that immune protection strategies can enhance MSC therapeutic efficacy by prolonging their survival and maintaining their biological functions. Among various immune protection strategies, biomaterial-based scaffolds or cell encapsulation systems that mediate the interaction between transplanted MSCs and the host immune system or spatially isolate MSCs from the immune system for a specific time period have shown great promise. In this review, we provide a comprehensive overview of these biomaterial-based immune protection strategies employed for exogenous MSCs, highlighting the crucial role of modulating the immune microenvironment. Each strategy is critically examined, discussing its strengths, limitations, and potential applications in MSC-based tissue engineering. By elucidating the mechanisms behind immune rejection and exploring immune protection strategies, we aim to address the challenges faced by MSC-based tissue engineering and pave the way for enhancing the therapeutic outcomes of MSC therapies. The insights gained from this review will contribute to the development of more effective strategies to protect transplanted MSCs from immune rejection and enable their successful application in regenerative medicine.

TolDC Restores the Balance of Th17/Treg via Aryl Hydrocarbon Receptor to Attenuate Colitis

BACKGROUND

Tolerogenic dendritic cells (TolDCs) have been evidenced to trigger regulatory T cell's (Treg's) differentiation and be involved in the pathogenesis of Crohn's disease (CD). Aryl hydrocarbon receptor (AhR) plays a crucial role in the differentiation of TolDCs, although the mechanism remains vague. This study aimed to evaluate the role of AhR in TolDCs formation, which may affect Th17/Treg balance in CD.

METHODS

Colon biopsy specimens were obtained from healthy controls and patients with CD. Wild type (WT) and AhR-/- mice were induced colitis by drinking dextran sulphate sodium (DSS) with or without 6-formylindolo 3,2-b carbazole (FICZ) treatment. Wild type and AhR-/- bone marrow-derived cells (BMDCs) were cultured under TolDCs polarization condition. Ratios of DCs surface markers were determined by flow cytometry. Enzyme-linked immunosorbent assay (ELISA) was performed to quantify the levels of interleukin (IL)-1β, transforming growth factor (TGF)-β and IL-10. Tolerogenic dendritic cells differentiated from BMDCs of WT or AhR-/- mice were adoptively transferred to DSS-induced WT colitis mice.

RESULTS

Patients with CD showed less AhR expression and activation in their inflamed colon regions. Compared with WT mice, AhR-/- mice experienced more severe colitis. Tolerogenic dendritic cells and Tregs were both decreased in the colon of AhR-/- colitis mice, while Th17 cells were upregulated. In vitro, compared with WT DCs, AhR-deficient DCs led to less TolDC formation. Furthermore, intestinal inflammation in WT colitis mice, which transferred with AhR-/- TolDCs, showed no obvious improvement compared with those transferred with WT TolDCs, as evidenced by no rescues of Th17/Treg balance.

CONCLUSIONS

Activation of AhR attenuates experimental colitis by modulating the balance of TolDCs and Th17/Treg. The AhR modulation of TolDCs may be a viable therapeutic approach for CD.

Current Treatments, Emerging Therapeutics, and Natural Remedies for Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a chronic, lifelong disorder characterized by inflammation of the gastrointestinal (GI) tract. The exact etiology of IBD remains incompletely understood due to its multifaceted nature, which includes genetic predisposition, environmental factors, and host immune response dysfunction. Currently, there is no cure for IBD. This review discusses the available treatment options and the challenges they present. Importantly, we examine emerging therapeutics, such as biologics and immunomodulators, that offer targeted treatment strategies for IBD. While many IBD patients do not respond adequately to most biologics, recent clinical trials combining biologics with small-molecule drugs (SMDs) have provided new insights into improving the IBD treatment landscape. Furthermore, numerous novel and specific therapeutic targets have been identified. The high cost of IBD drugs poses a significant barrier to treatment, but this challenge may be alleviated with the development of more affordable biosimilars. Additionally, emerging point-of-care protein biomarkers from serum and plasma are showing potential for enhancing the precision of IBD diagnosis and prognosis. Several natural products (NPs), including crude extracts, small molecules, and peptides, have demonstrated promising anti-inflammatory activity in high-throughput screening (HTS) systems and advanced artificial intelligence (AI)-assisted platforms, such as molecular docking and ADMET prediction. These platforms are advancing the search for alternative IBD therapies derived from natural sources, potentially leading to more affordable and safer treatment options with fewer side effects.

From ancient wisdom to modern science: Gut microbiota sheds light on property theory of traditional Chinese medicine

The property theory of traditional Chinese medicine (TCM) has been practiced for thousands of years, playing a pivotal role in the clinical application of TCM. While advancements in energy metabolism, chemical composition analysis, machine learning, ion current modeling, and supercritical fluid technology have provided valuable insight into how aspects of TCM property theory may be measured, these studies only capture specific aspects of TCM property theory in isolation, overlooking the holistic perspective inherent in TCM. To systematically investigate the modern interpretation of the TCM property theory from multidimensional perspectives, we consulted the Chinese Pharmacopoeia (2020 edition) to compile a list of Chinese materia medica (CMM). Then, using the Latin names of each CMM and gut microbiota as keywords, we searched the PubMed database for relevant research on gut microbiota and CMM. The regulatory patterns of different herbs on gut microbiota were then summarized from the perspectives of the four natures, the five flavors and the meridian tropism. In terms of the four natures, we found that warm-natured medicines promoted the colonization of specific beneficial bacteria, while cold-natured medicines boosted populations of some beneficial bacteria while suppressing pathogenic bacteria. Analysis of the five flavors revealed that sweet-flavored and bitter-flavored CMMs positively influenced beneficial bacteria while inhibiting harmful bacteria. CMMs with different meridian tropism exhibited complex modulative patterns on gut microbiota, with Jueyin (Liver) and Taiyin (Lung) meridian CMMs generally exerting a stronger effect. The gut microbiota may be a biological indicator for characterizing the TCM property theory, which not only enhances our understanding of classic TCM theory but also contributes to its scientific advancement and application in healthcare. Please cite this article as: Yang YN, Zhan JG, Cao Y, Wu CM. From ancient wisdom to modern science: Gut microbiota sheds light on property theory of traditional Chinese medicine. J Integr Med 2024; 22(4): 413-445.

Tryptophan metabolism and piglet diarrhea: Where we stand and the challenges ahead

The intestinal architecture of piglets is vulnerable to disruption during weaning transition and leads to diarrhea, frequently accompanied by inflammation and metabolic disturbances (including amino acid metabolism). Tryptophan (Trp) plays an essential role in orchestrating intestinal immune tolerance through its metabolism via the kynurenine, 5-hydroxytryptamine, or indole pathways, which could be dictated by the gut microbiota either directly or indirectly. Emerging evidence suggests a strong association between piglet diarrhea and Trp metabolism. Here we aim to summarize the intricate balance of microbiota-host crosstalk by analyzing alterations in both the host and microbial pathways of Trp and discuss how Trp metabolism may affect piglet diarrhea. Overall, this review could provide valuable insights to explore effective strategies for managing piglet diarrhea and the related challenges.

A decade of insight: bibliometric analysis of gut microbiota's role in osteoporosis (2014-2024)

Purpose

Osteoporosis represents a profound challenge to public health, underscoring the critical need to dissect its complex etiology and identify viable targets for intervention. Within this context, the gut microbiota has emerged as a focal point of research due to its profound influence on bone metabolism. Despite this growing interest, the literature has yet to see a bibliometric study addressing the gut microbiota's contribution to both the development and management of osteoporosis. This study aims to fill this gap through an exhaustive bibliometric analysis. Our objective is to uncover current research hotspots, delineate key themes, and identify future research trends. In doing so, we hope to provide direction for future studies and the development of innovative treatment methods.

Methods

Relevant publications in this field were retrieved from the Web of Science Core Collection database. We used VOSviewer, CiteSpace, an online analysis platform and the R package "Bibliometrix" for bibliometric analysis.

Results

A total of 529 publications (including 351 articles and 178 reviews) from 61 countries, 881 institutions, were included in this study. China leads in publication volume and boast the highest cumulative citation. Shanghai Jiao Tong University and Southern Medical University are the leading research institutions in this field. Nutrients contributed the largest number of articles, and J Bone Miner Res is the most co-cited journal. Of the 3,166 scholars who participated in the study, Ohlsson C had the largest number of articles. Li YJ is the most co-cited author. "Probiotics" and "inflammation" are the keywords in the research.

Conclusion

This is the first bibliometric analysis of gut microbiota in osteoporosis. We explored current research status in recent years and identified frontiers and hot spots in this research field. We investigate the impact of gut microbiome dysregulation and its associated inflammation on OP progression, a topic that has garnered international research interest in recent years. Additionally, our study delves into the potential of fecal microbiota transplantation or specific dietary interventions as promising avenues for future research, which can provide reference for the researchers who focus on this research filed.

Exploring potential polysaccharide utilization loci involved in the degradation of typical marine seaweed polysaccharides by Bacteroides thetaiotaomicron

Introduction

Research on the mechanism of marine polysaccharide utilization by Bacteroides thetaiotaomicron has drawn substantial attention in recent years. Derived from marine algae, the marine algae polysaccharides could serve as prebiotics to facilitate intestinal microecological balance and alleviate colonic diseases. Bacteroides thetaiotaomicron, considered the most efficient degrader of polysaccharides, relates to its capacity to degrade an extensive spectrum of complex polysaccharides. Polysaccharide utilization loci (PULs), a specialized organization of a collection of genes-encoded enzymes engaged in the breakdown and utilization of polysaccharides, make it possible for Bacteroides thetaiotaomicron to metabolize various polysaccharides. However, there is still a paucity of comprehensive studies on the procedure of polysaccharide degradation by Bacteroides thetaiotaomicron.

Methods

In the current study, the degradation of four kinds of marine algae polysaccharides, including sodium alginate, fucoidan, laminarin, and Pyropia haitanensis polysaccharides, and the underlying mechanism by Bacteroides thetaiotaomicron G4 were investigated. Pure culture of Bacteroides thetaiotaomicron G4 in a substrate supplemented with these polysaccharides were performed. The change of OD600, total carbohydrate contents, and molecular weight during this fermentation were determined. Genomic sequencing and bioinformatic analysis were further performed to elucidate the mechanisms involved. Specifically, Gene Ontology (GO) annotation, Clusters of Orthologous Groups (COG) annotation, and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment were utilized to identify potential target genes and pathways.

Results

Underlying target genes and pathways were recognized by employing bioinformatic analysis. Several PULs were found that are anticipated to participate in the breakdown of these four polysaccharides. These findings may help to understand the interactions between these marine seaweed polysaccharides and gut microorganisms.

Discussion

The elucidation of polysaccharide degradation mechanisms by Bacteroides thetaiotaomicron provides valuable insights into the utilization of marine polysaccharides as prebiotics and their potential impact on gut health. Further studies are warranted to explore the specific roles of individual PULs and their contributions to polysaccharide metabolism in the gut microbiota.

Bacteroides thetaiotaomicron and Faecalibacterium prausnitzii served as key components of fecal microbiota transplantation to alleviate colitis

Fecal microbiota transplantation (FMT) is a promising therapy for inflammatory bowel disease (IBD) via rectifying gut microbiota. The aim of this study was to identify a mechanism of how specific bacteria-associated immune response contributes to alleviated colitis. Forty donors were divided into high (donor H) and low (donor L) groups according to the diversity and the abundance of Bacteroides and Faecalibacterium by 16S rRNA sequencing. FMT was performed on dextran sulfate sodium (DSS)-induced colitis in mice. Mice with colitis showed significant improvement in intestinal injury and immune imbalance after FMT with group donor H (P < 0.05). Bacteroides thetaiotaomicron and Faecalibacterium prausnitzii were identified as targeted strains in donor feces by real-time PCR and droplet digital PCR. Mice with colitis were treated with mono- or dual-bacterial gavage therapy. Dual-bacterial therapy significantly ameliorated intestinal injury compared with mono-bacterial therapy (P < 0.05). Dual-bacterial therapy increased the M2/M1 macrophage polarization and improved the Th17/Treg imbalance and elevated IL-10 production by Tregs compared with the DSS group (P < 0.05). Metabolomics showed increased abundance of lecithin in the glycerophospholipid metabolism pathway. In conclusion, B. thetaiotaomicron and F. prausnitzii, as the key bacteria in donor feces, alleviate colitis in mice. The mechanism may involve increasing lecithin and regulating IL-10 production of intestinal Tregs.NEW & NOTEWORTHY We demonstrate that donors with high abundance of Bacteroides and Faecalibacterium ameliorate dextran sulfate sodium (DSS)-induced colitis in mice by fecal microbiota transplantation (FMT). The combination therapy of Bacteroides thetaiotaomicron and Faecalibacterium prausnitzii is superior to mono-bacterial therapy in ameliorating colitis in mice, of which mechanism may involve promoting lecithin and inducing IL-10 production of intestinal Tregs.

Pretreatment with an antibiotics cocktail enhances the protective effect of probiotics by regulating SCFA metabolism and Th1/Th2/Th17 cell immune responses

BACKGROUND

Probiotics are a potentially effective therapy for inflammatory bowel disease (IBD); IBD is linked to impaired gut microbiota and intestinal immunity. However, the utilization of an antibiotic cocktail (Abx) prior to the probiotic intervention remains controversial. This study aims to identify the effect of Abx pretreatment from dextran sulfate sodium (DSS)-induced colitis and to evaluate whether Abx pretreatment has an enhanced effect on the protection of Clostridium butyricum Miyairi588 (CBM) from colitis.

RESULTS

The inflammation, dysbiosis, and dysfunction of gut microbiota as well as T cell response were both enhanced by Abx pretreatment. Additionally, CBM significantly alleviated the DSS-induced colitis and impaired gut epithelial barrier, and Abx pretreatment could enhance these protective effects. Furthermore, CBM increased the benefit bacteria abundance and short-chain fatty acids (SCFAs) level with Abx pretreatment. CBM intervention after Abx pretreatment regulated the imbalance of cytokines and transcription factors, which corresponded to lower infiltration of Th1 and Th17 cells, and increased Th2 cells.

CONCLUSIONS

Abx pretreatment reinforced the function of CBM in ameliorating inflammation and barrier damage by increasing beneficial taxa, eliminating pathogens, and inducing a protective Th2 cell response. This study reveals a link between Abx pretreatment, microbiota, and immune response changes in colitis, which provides a reference for the further application of Abx pretreatment before microbiota-based intervention.

Gut microbiota-based discovery of Houttuyniae Herba as a novel prebiotic of Bacteroides thetaiotaomicron with anti-colitis activity

Ulcerative colitis (UC) represents an inflammatory disease characterized by fluctuations in severity, posing substantial challenges in treatment. The gut microbiota plays a pivotal role in the pathogenesis of UC. This study sought to identify drugs specifically targeting the gut microbiota to mitigate UC. We initiated a meta-analysis on gut microbiota in UC patients to identify UC-associated bacterial strains. Subsequently, we screened 164 dietary herbal medicines in vitro to identify potential prebiotics for the UC-associated bacterium, Bacteroides thetaiotaomicron. The DSS-induced colitis mouse model was utilized to evaluate the anti-colitis efficacy of the identified dietary herbal medicine. Full-length 16 S rRNA amplicon sequencing was employed to observe changes in gut microbiota following dietary herbal medicine intervention. The relative abundance of Bacteroides was notably diminished in UC patients compared to their healthy counterparts. B. thetaiotaomicron exhibited an inverse relationship with UC symptoms, indicating its potential as an anti-colitis agent. In vitro assessments revealed that H. Herba significantly bolstered the proliferation of B. thetaiotaomicron. Further experiments showed that treating DSS-induced mice with an aqueous extract of H. Herba considerably alleviated colitis indicators such as weight loss, colon shortening, disease activity score (DAI), and systemic inflammation. Microbial analysis revealed B. thetaiotaomicron as the sole bacterium substantially augmented by H. Herba in vivo. Overall H. Herba emerges as a promising prebiotic for B. thetaiotaomicron, offering significant anti-colitis benefits. Employing a gut microbiota-centric approach proves valuable in the quest for drug discovery.This study provides a new paradigm for drug discovery that targets the gut microbiota to treat UC.

The dynamic shifts of IL-10-producing Th17 and IL-17-producing Treg in health and disease: a crosstalk between ancient "Yin-Yang" theory and modern immunology

The changes in T regulatory cell (Treg) and T helper cell (Th) 17 ratios holds paramount importance in ensuring internal homeostasis and disease progression. Recently, novel subsets of Treg and Th17, namely IL-17-producing Treg and IL-10-producing Th17 have been identified. IL-17-producing Treg and IL-10-producing Th17 are widely considered as the intermediates during Treg/Th17 transformation. These "bi-functional" cells exhibit plasticity and have been demonstrated with important roles in multiple physiological functions and disease processes. Yin and Yang represent opposing aspects of phenomena according to the ancient Chinese philosophy "Yin-Yang" theory. Furthermore, Yin can transform into Yang, and vice versa, under specific conditions. This theory has been widely used to describe the contrasting functions of immune cells and molecules. Therefore, immune-activating populations (Th17, M1 macrophage, etc.) and immune overreaction (inflammation, autoimmunity) can be considered Yang, while immunosuppressive populations (Treg, M2 macrophage, etc.) and immunosuppression (tumor, immunodeficiency) can be considered Yin. However, another important connotation of "Yin-Yang" theory, the conversion between Yin and Yang, has been rarely documented in immune studies. The discovery of IL-17-producing Treg and IL-10-producing Th17 enriches the meaning of "Yin-Yang" theory and further promotes the relationship between ancient "Yin-Yang" theory and modern immunology. Besides, illustrating the functions of IL-17-producing Treg and IL-10-producing Th17 and mechanisms governing their differentiation provides valuable insights into the mechanisms underlying the dynamically changing statement of immune statement in health and diseases.

peu-MIR2916-p3-enriched garlic exosomes ameliorate murine colitis by reshaping gut microbiota, especially by boosting the anti-colitic Bacteroides thetaiotaomicron

Plant-derived exosome-like nanoparticles (ELNs) have drawn considerable attention for oral treatment of colonic diseases. However, the roles of ELNs derived from garlic on colitis remain unclear. Here, we demonstrate that garlic ELNs (GELNs), with desirable particle sizes (79.60 nm) and trafficking large amounts of functional proteins and microRNAs, stably roam in the gut and confer protection against ulcerative colitis (UC). In mice with DSS-induced colitis, orally administered GELNs effectively ameliorated bloody diarrhea, normalized the production of proinflammatory cytokines, and prevented colonic barrier impairment. Mechanistically, GELNs were taken up by gut microbes and reshaped DSS-induced gut microbiota dysbiosis, in which Bacteroides was the dominant respondent genus upon GELNs treatment. Notably, GELNs-enriched peu-MIR2916-p3 specifically promoted the growth of Bacteroides thetaiotaomicron, an intestinal symbiotic bacterium with palliative effects on colitis. Our findings provide new insights into the medicinal application of GELNs and highlight their potential as natural nanotherapeutic agents for preventing and treating UC.

Bacteroides thetaiotaomicron and its inactivated bacteria ameliorate colitis by inhibiting macrophage activation

BACKGROUND

Studies have demonstrated that Bacteroides thetaiotaomicron (BT) has protective effect against colon inflammation in murine models. Macrophages play an important role in gut immunity. However, the specific mechanisms of BT on macrophage are still unelucidated. Thus, our study investigates the anti-inflammatory effect of BT and its heat-treated inactivated bacteria on experimental colitis and macrophages.

METHODS

A dextran sulfate sodium (DSS)-induced acute colitis model with male C57BL/6 mice, BT (ATCC29148) strain, THP1 cell lines were used in this study. Live and heat-treated inactivated BT (IBT) solution (1 × 10^9cfu/ml) were intragastrically gavaged daily for 14 days. Colonic inflammation was determined by the disease activity index (DAI) score, colon length, histological score, and inflammatory factors. THP1 cells were induced towards M1, then treated with different concentrations of inactivated BT solution and p38 inhibitor. Western blotting, immunohistochemistry, immunofluorescence and qRT-PCR were performed to assess the levels of inflammatory cytokines and molecules of MAPK pathway including IL-6, TNF-α, IL-1β, IL-22, p38 and phosphor-p38 expressions. Moreover, 16S rRNA sequencing of colitis murine fecal samples was applied to investigate the influence of supplementation of BT to the gut microbiota homeostasis.

RESULTS

Both live and heat-treated inactivated BT decreased the DAI and histological scores as well as levels of inflammatory factors, particularly IL-6 while increasing IL-22 of DSS-induced colitis murine models. The cell experiments showed that inactivated BT downregulates IL-6 expression in THP1 via inhibiting p38 phosphorylation and affecting M1 polarization. Moreover, the 16S rRNA sequencing results showed that BT and IBT gavage could increase beta-diversity of gut flora in DSS-induced colitis mice. Furthermore, the significance test for differences between the groups showed that BT could increase Faecalebaculum, Lactobacillus and Bacteroides, while decreasing Akkermansia.

CONCLUSION

In summary, our findings imply that BT and its heat-treated inactivated bacteria exert a protective effect by suppressing macrophage-induced IL-6 through the inhibition of p38 MAPK pathway and ameliorating intestinal gut dysbiosis in experimental colitis.

Bacteroides methylmalonyl-CoA mutase produces propionate that promotes intestinal goblet cell differentiation and homeostasis

Propionate is a short-chain fatty acid that is generated upon microbiome-mediated fiber fermentation in the intestine. By modulating immune and metabolic pathways, propionate exerts many health benefits. Key bacterial species, such as Bacteroides thetaiotaomicron, generate propionate, but the biochemical pathways and specific functions remain undetermined. We identified a gene operon-encoding methylmalonyl-CoA mutase (MCM) that contributes to propionate biosynthesis in B. thetaiotaomicron. Colonization of germ-free mice with wild-type or MCM-deficient strains as well as in vitro examination demonstrated that MCM-mediated propionate production promotes goblet cell differentiation and mucus-related gene expression. Intestinal organoids lacking the propionate receptor, GPR41, showed reduced goblet cell differentiation upon MCM-mediated propionate production. Furthermore, although wild-type B. thetaiotaomicron alleviated DSS-induced intestinal inflammation, this effect was abolished in mice receiving the MCM-deficient strain but restored upon propionate supplementation. These data emphasize the critical role of MCM-mediated propionate biosynthesis in goblet cell differentiation, offering potential pathways to ameliorate colitis.

Atractylodes macrocephala Koidz polysaccharide improves glycolipid metabolism disorders through activation of aryl hydrocarbon receptor by gut flora-produced tryptophan metabolites

Polysaccharides are known to confer protection against glycolipid metabolism disorders (GMD) by regulating intestinal flora. In this study, a heterogeneous acidic heteropolysaccharide with high molecular weight mainly composed of fructose was isolated from Atractylodes macrocephala Koidz (AMP). Supplementation with AMP was shown to improve diet-induced GMD in a rat model, including decreasing the levels of serum triglycerides, total cholesterol, and glucose, and improving hepatic lipidosis and islet cells morphologies. AMP-treated rats also exhibited modified intestinal flora with enrichments of intestinal Lactobacillus and Rothia species, which was accompanied by increased tryptophan metabolites such as indole-3-propionic acid, indole, tryptamine, and tryptophol. These metabolites promote the expression of intestinal aryl hydrocarbon receptor (AhR) in nuclear fractions. AhR activation increased the expression levels of IL-22 and GLP-1 proteins and mRNA. IL-22 reduced systemic LPS by upregulating the expression of tight junction proteins, antimicrobial peptides, and mucin to ameliorate intestinal barrier function, and activated the hepatic IL-22R/Stat3/Acox1 signaling pathway to improve lipid metabolism. GLP-1 activated the pancreatic GLP-1R/p-CREB signaling pathway to ameliorate β-cell injury and improve insulin resistance. Therefore, the intestinal microbial-tryptophan metabolism-AhR pathway was deduced to be a mechanism by which this polysaccharide improves GMD.

Gut microbiome, metabolome, host immunity associated with inflammatory bowel disease and intervention of fecal microbiota transplantation

Gut dysbiosis has been associated with inflammatory bowel disease (IBD), one of the most common gastrointestinal diseases. The microbial communities play essential roles in host physiology, with profound effects on immune homeostasis, directly or via their metabolites and/or components. There are increasing clinical trials applying fecal microbiota transplantation (FMT) with Crohn's disease (CD) and ulcerative colitis (UC). The restoration of dysbiotic gut microbiome is considered as one of the mechanisms of FMT therapy. In this work, latest advances in the alterations in gut microbiome and metabolome features in IBD patients and experimental mechanistic understanding on their contribution to the immune dysfunction were reviewed. Then, the therapeutic outcomes of FMT on IBD were summarized based on clinical remission, endoscopic remission and histological remission of 27 clinical trials retrieved from PubMed which have been registered on ClinicalTrials.gov with the results been published in the past 10 years. Although FMT is established as an effective therapy for both subtypes of IBD, the promising outcomes are not always achieved. Among the 27 studies, only 11 studies performed gut microbiome profiling, 5 reported immune response alterations and 3 carried out metabolome analysis. Generally, FMT partially restored typical changes in IBD, resulted in increased α-diversity and species richness in responders and similar but less pronounced shifts of patient microbial and metabolomics profiles toward donor profiles. Measurements of immune responses to FMT mainly focused on T cells and revealed divergent effects on pro-/anti-inflammatory functions. The very limited information and the extremely confounding factors in the designs of the FMT trials significantly hindered a reasonable conclusion on the mechanistic involvement of gut microbiota and metabolites in clinical outcomes and an analysis of the inconsistencies.

Human umbilical cord mesenchymal stem cells alleviated TNBS-induced colitis in mice by restoring the balance of intestinal microbes and immunoregulation

AIMS

Human umbilical cord mesenchymal stem cells (HUMSCs) have been documented to be effective for several immune disorders including inflammatory bowel diseases (IBD). However, it remains unclear how HUMSCs function in regulating immune responses and intestinal flora in the trinitrobenzene sulfonic acid (TNBS)-induced IBD model.

MATERIALS AND METHODS

We assessed the regulatory effects of HUMSCs on the gut microbiota, T lymphocyte subpopulations and related immune cytokines in the TNBS-induced IBD model. The mice were divided into the normal, TNBS, and HUMSC-treated groups. The effect of HUMSCs was evaluated by Hematoxylin and Eosin (H&E) staining, fluorescence-activated cell sorting (FACS), and enzyme-linked immunosorbent assay (ELISA) analyses. Metagenomics Illumina sequencing was conducted for fecal samples.

KEY FINDINGS

We demonstrated that the disease symptoms and pathological changes in the colon tissues of TNBS-induced colitis mice were dramatically ameliorated by HUMSCs, which improved the gut microbiota and rebalanced the immune system, increasing the abundance of healthy bacteria (such as Lactobacillus murinus and Lactobacillus johnsonii), the Firmicutes/Bacteroidetes ratio, and the proportion of Tregs; the Th1/Th17 ratio was decreased. Consistently, the expression levels of IFN-γ and IL-17 were significantly decreased, and transforming growth factor-β1 (TGF-β1) levels were significantly increased in the plasma of colitis mice HUMSC injection.

SIGNIFICANCE

Our experiment revealed that HUMSCs mitigate acute colitis by regulating the rebalance of Th1/Th17/Treg cells and related cytokines and remodeling the gut microbiota, providing potential future therapeutic targets in IBD.

The interplay between the microbiota, diet and T regulatory cells in the preservation of the gut barrier in inflammatory bowel disease

Inflammatory bowel disease (IBD) is becoming more common in the Western world due to changes in diet-related microbial dysbiosis, genetics and lifestyle. Incidences of gut permeability can predate IBD and continued gut barrier disruptions increase the exposure of bacterial antigens to the immune system thereby perpetuating chronic inflammation. Currently, most of the approved IBD therapies target individual pro-inflammatory cytokines and pathways. However, they fail in approximately 50% of patients due to their inability to overcome the redundant pro inflammatory immune responses. There is increasing interest in the therapeutic potential of T regulatory cells (Tregs) in inflammatory conditions due to their widespread capability to dampen inflammation, promote tolerance of intestinal bacteria, facilitate healing of the mucosal barrier and ability to be engineered for more targeted therapy. Intestinal Treg populations are inherently shaped by dietary molecules and gut microbiota-derived metabolites. Thus, understanding how these molecules influence Treg-mediated preservation of the intestinal barrier will provide insights into immune tolerance-mediated mucosal homeostasis. This review comprehensively explores the interplay between diet, gut microbiota, and immune system in influencing the intestinal barrier function to attenuate the progression of colitis.

Tryptophan Metabolism and Gut Microbiota: A Novel Regulatory Axis Integrating the Microbiome, Immunity, and Cancer

Tryptophan metabolism and gut microbiota form an integrated regulatory axis that impacts immunity, metabolism, and cancer. This review consolidated current knowledge on the bidirectional interactions between microbial tryptophan processing and the host. We focused on how the gut microbiome controls tryptophan breakdown via the indole, kynurenine, and serotonin pathways. Dysbiosis of the gut microbiota induces disruptions in tryptophan catabolism which contribute to disorders like inflammatory conditions, neuropsychiatric diseases, metabolic syndromes, and cancer. These disruptions affect immune homeostasis, neurotransmission, and gut-brain communication. Elucidating the mechanisms of microbial tryptophan modulation could enable novel therapeutic approaches like psychobiotics and microbiome-targeted dietary interventions. Overall, further research on the microbiota-tryptophan axis has the potential to revolutionize personalized diagnostics and treatments for improving human health.

Interactions between dietary cholesterol and intestinal flora and their effects on host health

The interactions between dietary cholesterol and intestinal microbiota strongly affect host health. In recent years, relevant studies have greatly advanced this field and need to be summarized to deepen the understanding of dietary cholesterol-intestinal microbiota interactions and their effects on host health. This review covers the most recent frontiers on the effects of dietary cholesterol on the intestinal microbiota and its metabolites, the metabolism of cholesterol by the intestinal microbiota, and the effects of the interactions on host health. Several animal-feeding studies reported that dietary cholesterol altered different intestinal microbiota in the body, while mainly causing alterations in intestinal microbial metabolites such as bile acids, short-chain fatty acids, and tryptophan derivatives. Alterations in these metabolites may be a novel mechanism mediating cholesterol-related diseases. The cholesterol microbial metabolite, coprostanol, has a low absorption rate and is excreted in the feces. Thus, microbial conversion of cholesterol-to-coprostanol may be an important way of cholesterol-lowering by the organism. Cholesterol-3-sulfate is a recently discovered microbial metabolite of cholesterol, mainly metabolized by Bacteroides containing the Bt_0416 gene. Its effects on host health have been preliminarily characterized and are mainly related to immune modulation and repair of the intestinal epithelium.

Effects of dietary supplement with licorice and rutin mixture on production performance, egg quality, antioxidant capacity, and gut microbiota in quails (Turnix tanki)

This study was conducted to evaluate the effect of licorice and rutin on production performance, egg quality, and mucosa antioxidant levels in Chinese yellow quail. A total of 240 Chinese Yellow Quail (400-day-old) were randomly distributed into 5 groups: the Control group, fed with a basic diet; the LR1 group, fed with basal diet supplemented with 300 + 100 mg licorice and rutin mixture/kg diet; the LR2 group, fed with basal diet supplemented with 300 + 200 mg licorice and rutin mixture/kg diet; the LR3 group, fed with basal diet supplemented with 600 + 100 mg licorice and rutin mixture/kg diet and the LR4 group, fed with basal diet supplemented with 600 + 200 mg licorice and rutin mixture/kg diet. Compared with the control, supplementation with the licorice and rutin mixture improved the laying rate and eggshell thickness whereas decreased the feed conversion ratio of quails. Moreover, dietary supplementation with the licorice and rutin mixture improved the antioxidant capacity by increasing the activity of the superoxide dismutase (SOD) level and decreasing the concentration of malondialdehyde (MDA) in the jejunal mucosa. The licorice and rutin mixture altered the composition of intestinal microbiota by influencing the relative abundances of Bacteroidetes and Bacteroides. The relative abundances of the Bacteroidetes were significantly related to the laying rate of quails. In addition, the mixture of licorice and rutin was also effective in reducing the relative abundance of intestinal Proteobacteria and Enterobacter in quails, reducing the accumulation of antibiotic-resistance genes. The results revealed that supplementation of licorice and rutin mixture to the diet improved production performance, egg quality, and antioxidant capacity and modified the composition of intestinal microbiota in quails. This study provides a reference for Chinese herbal additives to promote production performance by modulating quail gut microbes.

Modulation of tryptophan metabolism via AHR-IL22 pathway mediates the alleviation of DSS-induced colitis by chitooligosaccharides with different degrees of polymerization

Oral administration of chitooligosaccharides (COS) has been reported to alleviate colitis in mice. However, the mechanism of action of COS with specific polymerization degree on gut inflammation and metabolism remains unclear. This study aimed to investigate the effects of chitobiose (COS2), chitotetraose (COS4), and chitohexaose (COS6) on colitis, and to elucidate their underlying mechanisms. COS2, COS4, and COS6 were able to significantly alleviate colonic injury and inflammation levels. COS6 has the best anti-inflammatory effect. Furthermore, COS6 could down-regulate the level of indoleamine-2,3-dioxygenase1 (IDO1) and restore the levels of indole, indoleacetic-3-acid (IAA), and indole-3-carbaldehyde (I3A) in the cecum of chronic colitis mice (p < 0.05), thereby regulating tryptophan metabolism. In the aromatic hydrocarbon receptor-IL-22 (AHR-IL-22) pathway, although there were differences between chronic colitis and acute colitis mice, COS intervention could restore the AHR-IL-22 pathway to normal, promote the expression of MUC2, and repair the intestinal mucosal barrier. In conclusion, the results of this study suggested that COS had a good inhibitory effect on IDO1 under inflammation and the changes of AHR and IL-22 levels at different stages of disease development. This provides new insights into the potential use of COS as a functional food for improving intestinal inflammation and metabolism.

In Vitro Fermentation of Polysaccharide from Edible Alga Enteromorpha clathrata by the Gut Microbiota of Patients with Ulcerative Colitis

Dietary intake of the sulfated polysaccharide from edible alga E. clathrata (ECP) has recently been illustrated to attenuate ulcerative colitis (UC) by targeting gut dysbiosis in mice. However, ECP is not easily absorbed in the gut and, as a potential candidate for next-generation prebiotics development, how it is fermented by human gut microbiota has not been characterized. Here, using in vitro anaerobic fermentation and 16S high-throughput sequencing, we illustrate for the first time the detailed fermentation characteristics of ECP by the gut microbiota of nine UC patients. Our results indicated that, compared to that of glucose, fermentation of ECP by human gut microbiota produced a higher amount of anti-inflammatory acetate and a lower amount of pro-inflammatory lactate. Additionally, ECP fermentation helped to shape a more balanced microbiota composition with increased species richness and diversity. Moreover, ECP significantly stimulated the growth of anti-colitis bacteria in the human gut, including Bacteroides thetaiotaomicron, Bacteroides ovatus, Blautia spp., Bacteroides uniformis, and Parabacteroides spp. Altogether, our study provides the first evidence for the prebiotic effect of ECP on human gut microbiota and sheds new light on the development of ECP as a novel prebiotic candidate for the prevention and potential treatment of UC.

Intestinal microbiota controls graft-versus-host disease independent of donor-host genetic disparity

Acute graft-versus-host disease (aGVHD) remains a major limitation of allogeneic stem cell transplantation (SCT), and severe intestinal manifestation is the major cause of early mortality. Intestinal microbiota control MHC class II (MHC-II) expression by ileal intestinal epithelial cells (IECs) that promote GVHD. Here, we demonstrated that genetically identical mice of differing vendor origins had markedly different intestinal microbiota and ileal MHC-II expression, resulting in discordant GVHD severity. We utilized cohousing and antibiotic treatment to characterize the bacterial taxa positively and negatively associated with MHC-II expression. A large proportion of bacterial MHC-II inducers were vancomycin sensitive, and peri-transplant oral vancomycin administration attenuated CD4+ T cell-mediated GVHD. We identified a similar relationship between pre-transplant microbes, HLA class II expression, and both GVHD and mortality in a large clinical SCT cohort. These data highlight therapeutically tractable mechanisms by which pre-transplant microbial taxa contribute to GVHD independently of genetic disparity.

Tryptophan metabolism in health and disease

Tryptophan (Trp) metabolism primarily involves the kynurenine, 5-hydroxytryptamine, and indole pathways. A variety of bioactive compounds produced via Trp metabolism can regulate various physiological functions, including inflammation, metabolism, immune responses, and neurological function. Emerging evidence supports an intimate relationship between Trp metabolism disorder and diseases. The levels or ratios of Trp metabolites are significantly associated with many clinical features. Additionally, studies have shown that disease progression can be controlled by modulating Trp metabolism. Indoleamine-2,3-dioxygenase, Trp-2,3-dioxygenase, kynurenine-3-monooxygenase, and Trp hydroxylase are the rate-limiting enzymes that are critical for Trp metabolism. These key regulatory enzymes can be targeted for treating several diseases, including tumors. These findings provide novel insights into the treatment of diseases. In this review, we have summarized the recent research progress on the role of Trp metabolites in health and disease along with their clinical applications.

Modulation of immunity by tryptophan microbial metabolites

Tryptophan (Trp) is an essential amino acid that can be metabolized via endogenous and exogenous pathways, including the Kynurenine Pathway, the 5-Hydroxyindole Pathway (also the Serotonin pathway), and the Microbial pathway. Of these, the Microbial Trp metabolic pathways in the gut have recently been extensively studied for their production of bioactive molecules. The gut microbiota plays an important role in host metabolism and immunity, and microbial Trp metabolites can influence the development and progression of various diseases, including inflammatory, cardiovascular diseases, neurological diseases, metabolic diseases, and cancer, by mediating the body's immunity. This review briefly outlines the crosstalk between gut microorganisms and Trp metabolism in the body, starting from the three metabolic pathways of Trp. The mechanisms by which microbial Trp metabolites act on organism immunity are summarized, and the potential implications for disease prevention and treatment are highlighted.

Diet-induced changes in fecal microbiota composition and diversity in dogs (Canis lupus familiaris): A comparative study of BARF-type and commercial diets

BACKGROUND

Diet is known to strongly modulate the composition of the gut microbiota, thereby affecting health conditions and disease. Natural BARF-type and commercial diets have been used for feeding pets (e.g. dogs and cats) promoting changes in the canine microbiota in terms of abundance, richness, and diversity that may favor certain metabolic processes and resistance to certain infectious agents. Therefore, the present study sought to identify microbiota changes in dogs fed with a BARF-type diet versus dogs fed with a commercial diet by sequencing the V4 region of the 16S rRNA gene.

METHODS

The microbiota of dogs fed with the BARF-diet (n = 20) and commercial-diet (n = 26) was studied using fecal samples. A metabarcoding strategy was employed by sequencing the V4 hypervariable region of the 16S rRNA gene using the Illumina HiSeq platform. DADA2 was used to assess the quality profile of the reads and to determine the core sample inference algorithm of the reads to infer amplicon sequence variants (ASVs). The taxonomic assignment was performed using sequences from the Silva v138 formatted reference database. The microbial diversity analysis was performed using the R package Phyloseq, which was used to calculate diversity and abundance indices and construct the respective graphs. Linear discriminant analysis (LDA) effect size analysis (LEfSe) was used to identify the differentially abundant taxa in the BARF group versus the commercial-diet group.

RESULTS

The diet causes changes in fecal microbiota composition and diversity, with richness and diversity being higher in BARF-fed dogs. Beta diversity analyses confirmed that diet is directly related to microbiota composition regardless of breed or sex. Differentially enriched taxa were identified in each of the diets as Fusobacterium, Bacteroides, and Clostridium perfringens in BARF-fed dogs and Prevotella, Turicibacter, Faecalibacterium, and Peptacetobacter (Clostridium) hiranonis, mostly relevant in carbohydrate metabolism, in commercial-fed dogs.

CONCLUSIONS

This study is the first one carried out in dogs from Colombia that seeks to identify changes in the intestinal microbiota concerning natural BARF type diet and commercial diet using a metabarcoding approach. Important differences were identified in terms of richness, diversity, and differentially enriched bacteria in each of the diets. The microbiota of dogs fed the BARF diet was characterized by higher richness and diversity compared to the commercial diet. However, it was identified that BARF-fed dogs can potentially acquire more opportunistic infections by pathogens of importance such as C. perfringens. Most of the taxa enriched in commercial diet-fed dogs are linked to carbohydrate metabolism, which may be directly related to diet composition.

Microbiome Alterations Driven by Trypanosoma cruzi Infection in Two Disjunctive Murine Models

Alterations caused by Trypanosoma cruzi in the composition of gut microbiome may play a vital role in the host-parasite interactions that shapes physiology and immune responses against infection. Thus, a better understanding of this parasite-host-microbiome interaction may yield relevant information in the comprehension of the pathophysiology of the disease and the development of new prophylactic and therapeutic alternatives. Therefore, we implemented a murine model with two mice strains (BALB/c and C57BL/6) to evaluate the impact of Trypanosoma cruzi (Tulahuen strain) infection on the gut microbiome utilizing cytokine profiling and shotgun metagenomics. Higher parasite burdens were observed in cardiac and intestinal tissues, including changes in anti-inflammatory (interleukin-4 [IL-4] and IL-10) and proinflammatory (gamma interferon, tumor necrosis factor alpha, and IL-6) cytokines. Bacterial species such as Bacteroides thetaiotaomicron, Faecalibaculum rodentium, and Lactobacillus johnsonii showed a decrease in relative abundance, while Akkermansia muciniphila and Staphylococcus xylosus increased. Likewise, as infection progressed, there was a decrease in gene abundances related to metabolic processes such as lipid synthesis (including short-chain fatty acids) and amino acid synthesis (including branched-chain amino acids). High-quality metagenomic assembled genomes of L. johnsonii and A. muciniphila among other species were reconstructed, confirming, functional changes associated with metabolic pathways that are directly affected by the loss of abundance of specific bacterial taxa. IMPORTANCE Chagas disease (CD) is caused by the protozoan Trypanosoma cruzi, presenting acute and chronic phases where cardiomyopathy, megaesophagus, and/or megacolon stand out. During the course of its life cycle, the parasite has an important gastrointestinal tract transit that leads to severe forms of CD. The intestinal microbiome plays an essential role in the immunological, physiological, and metabolic homeostasis of the host. Therefore, parasite-host-intestinal microbiome interactions may provide information on certain biological and pathophysiological aspects related to CD. The present study proposes a comprehensive evaluation of the potential effects of this interaction based on metagenomic and immunological data from two mice models with different genetic, immunological, and microbiome backgrounds. Our findings suggest that there are alterations in the immune and microbiome profiles that affect several metabolic pathways that can potentially promote the infection's establishment, progression, and persistence. In addition, this information may prove essential in the research of new prophylactic and therapeutic alternatives for CD.

Alleviative effects of natural plant polysaccharides against DSS-induced ulcerative colitis via inhibiting inflammation and modulating gut microbiota

Ulcerative colitis (UC) treatment usually involves either drug therapy or surgery. Natural food polysaccharides have showed great potential for preventing UC. In this study, the therapeutic effects of Cyclocarya paliurus (Batal.) Iljinskaja polysaccharide (CP) and Chinese yam polysaccharide (CYP) on dextran sodium sulfate (DSS)-induced mice UC model and their underlying mechanisms were explored. The results suggested that CP and CYP could improve colitis symptoms in DSS-induced mice, enhance the production of IL-10, inhibit cytokines (IL-1β, TNF-α) and reduce MPO activity. Furthermore, they maintained the integrity of intestine by improving the expression of mucin MUC-2, ZO-1 and occludin, which in turn reduced the contents of lipopolysaccharide binding protein (LBP) and endotoxin (ET) in serum and oxidative stress in liver. Finally, they modulated the composition and metabolism of gut microbiota. Notably, Alistipes and Bacteroides were the specific genera in CP and CYP groups, respectively. These findings indicated that polysaccharides might alleviate the development of colitis and inform other relevant studies.

Correlation between the intestinal microflora and peripheral blood Th1/Th2 balance in hypothyroidism during the first half of pregnancy

Objective

This study aimed to investigate the relationship between intestinal microflora characteristics and the peripheral blood T helper cell (Th)1/Th2 balance in patients with hypothyroidism during the first half of pregnancy.

Methods

The Th1/Th2 ratios in the peripheral blood of pregnant women in the hypothyroidism and control groups were determined using flow cytometry. The cytometric bead array assay was used to determine the serum levels of interleukin-2 (IL-2), IL-4, IL-6, IL-10, tumor necrosis factor (TNF)-α, and interferon (IFN)-γ. Moreover, 16S rRNA amplicon sequencing was used to determine the intestinal microbial composition in the two groups. Finally, the relationships between intestinal microflora, Th1/Th2 cells, cytokines, and clinical indicators were analyzed.

Results

C-reactive protein levels were higher in the hypothyroidism group than in the control group. In contrast to the control group, the hypothyroidism group showed an increase in Th1 cells and the Th1/Th2 ratio, and a decrease in Th2 cells. The hypothyroidism group had higher serum IL-2, TNF-α, and IFN-γ levels, and lower IL-10 levels, than the control group. The richness of the intestinal microflora in the hypothyroidism group increased whereas the diversity decreased. The linear discriminant analysis effect size revealed that the hypothyroidism group had a higher abundance of Prevotella and Faecalibacterium, but a lower abundance of Bacteroides, compared to the control group. Prevotella was positively correlated with Th1 cells, the Th1/2 ratio, and TNF-α. Bacteroides was positively correlated with Th2 cells and IL-10, but negatively correlated with Th1 cells, the Th1/2 ratio, TNF-α, and IFN-γ. The thyroid peroxidase antibody level was directly proportional to TNF-α.

Conclusion

A Th1/Th2 imbalance occurs in patients with hypothyroidism during the first half of pregnancy. Disorders of the intestinal microflora may lead to hypothyroidism during pregnancy by affecting the Th1/Th2 balance.

Gegen Qinlian decoction activates AhR/IL-22 to repair intestinal barrier by modulating gut microbiota-related tryptophan metabolism in ulcerative colitis mice

ETHNOPHARMACOLOGICAL RELEVANCE

Gegen Qinlian decoction (GQD) is a traditional Chinese medicine derived from Treatise on febrile diseases and is clinically used for the treatment of acute ulcerative colitis (UC). However, the potential mechanism of GQD treatment for UC remains elusive.

AIM OF STUDY

In this study, we aimed to explore the involvement of gut microbiota-related tryptophan metabolism in mediating protective effects of GQD against intestinal barrier damage.

MATERIALS AND METHODS

Mice with colitis were treated with 3% dextran sulfate sodium (DSS) for 6 days. The therapeutic effects of GQD in UC mice were examined based on body weight, disease activity index (DAI), organ index, length and pathological changes in the colon. The distribution of fluorescein isothiocyanate dextran (FITC-dextran) in the intestinal tract was observed using small animal imaging, while concentration of FITC-dextran in serum was detected using a fluorescein microplate analyser. Bacterial infiltration in colon tissues was observed by fluorescence in situ hybridisation (FISH), and the bacterial load in mesenteric lymph nodes (MLNs) was further examined through bacterial culture. Subsequently, colonic goblet cells were detected using Alcian blue staining. The tight junctions of the colonic epithelium were observed using transmission electron microscopy, and the expression of tight junction proteins was detected by immunofluorescence (IF) and western blot. In addition, flow cytometry was used to analyse the proportion of interleukin-22-positive (IL-22⁺) ILC3 cells in lamina propria lymphocytes, and the content of IL-22 in colon homogenates was determined using an ELISA kit. In addition, targeted tryptophan metabolomics was used to detect the concentration of indole derivatives produced by tryptophan metabolism in faeces, and 16S rDNA was used to investigate the composition and abundance of gut microbiota-related tryptophan metabolism.

RESULTS

Administration of GQD significantly alleviated the pathological symptoms, including weight loss, increased DAI score, changes in organ index, colon shortening, and colon pathological injury in UC mice. In addition, GQD reduced the diffusion of FITC-dextran in the intestinal tract, the content of FITC-dextran in serum, and bacterial infiltration in MLNs and colon tissues. Additionally, GQD significantly increased the number of colonic goblet cells, repaired the structure of epithelial tight junctions and increased the expression of tight junction proteins. Furthermore, GQD significantly increased the proportion of IL-22⁺ ILC3 in the lamina propria, the expression of CYP1A1 protein in colon tissue, and the level of IL-22 in colon homogenates. However, the above protective effects of GQD were inhibited by co-administration of GQD and aryl hydrocarbon receptor (AhR) antagonist. Additionally, GQD restored the content of indole derivatives generated by tryptophan metabolism, regulated the diversity of the gut microbiota, and significantly increased the abundance of genes related to tryptophan metabolism.

CONCLUSION

Our results confirmed that GQD repaired the damaged intestinal barrier in UC mice by regulating gut microbiota-related tryptophan metabolism and restoring the generation of indole derivatives to activate AhR-mediated IL-22 production.

Microbial Components and Effector Molecules in T Helper Cell Differentiation and Function

The mammalian intestines harbor trillions of commensal microorganisms composed of thousands of species that are collectively called gut microbiota. Among the microbiota, bacteria are the predominant microorganism, with viruses, protozoa, and fungi (mycobiota) making up a relatively smaller population. The microbial communities play fundamental roles in the maturation and orchestration of the immune landscape in health and disease. Primarily, the gut microbiota modulates the immune system to maintain homeostasis and plays a crucial role in regulating the pathogenesis and pathophysiology of inflammatory, neuronal, and metabolic disorders. The microbiota modulates the host immune system through direct interactions with immune cells or indirect mechanisms such as producing short-chain acids and diverse metabolites. Numerous researchers have put extensive efforts into investigating the role of microbes in immune regulation, discovering novel immunomodulatory microbial species, identifying key effector molecules, and demonstrating how microbes and their key effector molecules mechanistically impact the host immune system. Consequently, recent studies suggest that several microbial species and their immunomodulatory molecules have therapeutic applicability in preclinical settings of multiple disorders. Nonetheless, it is still unclear why and how a handful of microorganisms and their key molecules affect the host immunity in diverse diseases. This review mainly discusses the role of microbes and their metabolites in T helper cell differentiation, immunomodulatory function, and their modes of action.

Indole-3-propionic acid alleviates chondrocytes inflammation and osteoarthritis via the AhR/NF-κB axis

BACKGROUND

Osteoarthritis (OA) is a common chronic disease characterized by chronic inflammation and extracellular matrix degradation. Indole-3-propionic acid (IPA) is a tryptophan metabolite secreted by intestinal flora, which can exert anti-inflammatory effects in a variety of diseases. In this study, we further investigated the potential therapeutic role of IPA in OA and the underlying mechanism.

METHODS

IL-1β was utilized to induce chondrocyte inflammation. Then, the cytotoxicity of IPA on rat chondrocytes was assessed. Meanwhile, RT-qPCR, Griess reaction, ELISA, Western blot and immunofluorescence were performed to evaluate the expression of inflammatory factors and stromal proteins, and the NF-κB pathway in chondrocytes treated with IL-1β alone, with IPA or with aryl hydrocarbon receptor (AhR) knockdown. An OA rat model was established by anterior cruciate ligament transection, and hematoxylin-eosin staining, Safranin-O/Fast Green staining and immunochemistry were applied to estimate OA severity.

RESULTS

IPA did not affect cellular viability at concentrations up to 80 µM. IPA significantly inhibited the IL-1β-induced expression of inflammatory factors (Nitric oxide, PGE2, TNF-α, IL-6, iNOS and COX-2) and matrix-degrading enzymes (MMP-3, MMP-13 and ADAMTS-5), upregulated the expression of anabolic markers (aggrecan and collagen-II) and inactivated the NF-κB pathway. However, AhR knockdown could abolish the above protection capabilities and the suppression of the NF-κB pathway induced by IPA. Furthermore, IPA significantly reduced serum inflammatory cytokines expression, cartilage destruction and synovitis in vivo, demonstrating its protective role in OA progression.

CONCLUSION

IPA improved IL-1β-induced chondrocyte inflammation and extracellular matrix degradation through the AhR/NF-κB axis, which provides an innovative therapeutic strategy for OA.

Extracellular vesicles produced by the human gut commensal bacterium Bacteroides thetaiotaomicron elicit anti-inflammatory responses from innate immune cells

Bacterial extracellular vesicles (BEVs) produced by gut commensal bacteria have been proposed to play an important role in maintaining host homeostasis via interactions with the immune system. Details of the mediators and pathways of BEV-immune cell interactions are however incomplete. In this study, we provide evidence for the anti-inflammatory and immunomodulatory properties of extracellular vesicles produced by the prominent human gut commensal bacterium Bacteroides thetaiotaomicron (Bt BEVs) and identify the molecular mechanisms underlying their interaction with innate immune cells. Administration of Bt BEVs to mice treated with colitis-inducing dextran sodium sulfate (DSS) ameliorates the symptoms of intestinal inflammation, improving survival rate and reducing weight loss and disease activity index scores, in association with upregulation of IL-10 production in colonic tissue and in splenocytes. Pre-treatment (conditioning) of murine bone marrow derived monocytes (BMDM) with Bt BEVs resulted in higher ratio of IL-10/TNFα production after an LPS challenge when compared to LPS pre-conditioned or non-conditioned BMDM. Using the THP-1 monocytic cell line the interactions between Bt BEVs and monocytes/macrophages were shown to be mediated primarily by TLR2. Histone (H3K4me1) methylation analysis showed that Bt BEVs induced epigenetic reprogramming which persisted after infectious challenge, as revealed by increased levels of H3K4me1 in Bt BEV-conditioned LPS-challenged BMDM. Collectively, our findings highlight the important role of Bt BEVs in maintaining host immune homeostasis and raise the promising possibility of considering their use in immune therapies.

Ameliorative Effect of Saccharomyces cerevisiae JKSP39 on Fusobacterium nucleatum and Dextran Sulfate Sodium-Induced Colitis Mouse Model

The aim of this study was to evaluate the ability of the Saccharomyces cerevisiae strain with probiotic properties isolated from Tibetan kefir grains to ameliorate Fusobacterium nucleatum (Fn) infection and dextran sulfate sodium (DSS) treatment-induced murine model of colitis. The tolerance to simulated gastrointestinal conditions, hydrophobicity test, autoaggregation assay, and the antioxidant effect of strains was used to screen one strain with colonization and probiotic potential. The murine model of colitis was established by giving 10⁹ cfu Fn 3 weeks by intragastric administration and 3% DSS in water 1 week before sacrifice. The results indicated that S. cerevisiae JKSP39 (SC) possessed optimal probiotic characteristics in vitro. Supplementation with SC increased the body weight and the expression of anti-inflammatory cytokines (IL-4 and IL-10), while decreasing the disease activity index score and expression of proinflammatory cytokines (TNF-α, IL-6, and IL-17F) in mice undergoing experimental colitis as compared with the colitis model group. Additionally, tight junction proteins and the number of goblet cells per crypt were significantly increased in the SC group, which indicated that the gut barrier was well repaired. The mechanism of SC ameliorating Fn-DSS-induced colitis could be related to the decreased levels of reactive oxygen species (myeloperoxidase, total superoxide dismutase, catalase, H₂O₂, and malondialdehyde) in the colon, the inhibition of endoplasmic reticulum stress, and the regulation of gut microbiota.

The Therapeutic Role of Short-Chain Fatty Acids Mediated Very Low-Calorie Ketogenic Diet-Gut Microbiota Relationships in Paediatric Inflammatory Bowel Diseases

The very low-calorie ketogenic diet (VLCKD) has been recognized as a promising dietary regimen for the treatment of several diseases. Short-chain fatty acids (SCFAs) produced by anaerobic bacterial fermentation of indigestible dietary fibre in the gut have potential value for their underlying epigenetic role in the treatment of obesity and asthma-related inflammation through mediating the relationships between VLCKD and the infant gut microbiota. However, it is still unclear how VLCKD might influence gut microbiota composition in children, and how SCFAs could play a role in the treatment of inflammatory bowel disease (IBD). To overcome this knowledge gap, this review aims to investigate the role of SCFAs as key epigenetic metabolites that mediate VLCKD-gut microbiota relationships in children, and their therapeutic potential in IBD.