Gut microbiota-derived metabolites in the regulation of host immune responses and immune-related inflammatory diseases

On the Inheritance of Microbiome-Deficiency: Paediatric Functional Gastrointestinal Disorders, the Immune System and the Gut–Brain Axis

Like the majority of non-communicable diseases that have recently gained attention, functional gastrointestinal (GI) disorders (FGID) in both children and adults are caused by a variety of medical conditions. In general, while it is often thought that common conditions such as obesity may cause other problems, for example, asthma or mental health issues, more consideration needs to be given to the possibility that they could both be brought on by a single underlying problem. Based on the variations in non-communicable disease, in recent years, our group has been revisiting the exact role of the intestinal microbiome within the Vertebrata. While the metabolic products of the microbiome have a role to play in the adult, our tentative conclusion is that the fully functioning, mutualistic microbiome has a primary role: to transfer antigen information from the mother to the neonate in order to calibrate its immune system, allowing it to survive within the microbial environment into which it will emerge. Granted that the microbiome possesses such a function, logic suggests the need for a robust, flexible, mechanism allowing for the partition of nutrition in the mature animal, thus ensuring the continued existence of both the vertebrate host and microbial guest, even under potentially unfavourable conditions. It is feasible that this partition process acts by altering the rate of peristalsis following communication through the gut–brain axis. The final step of this animal–microbiota symbiosis would then be when key microbes are transferred from the female to her progeny, either live offspring or eggs. According to this scheme, each animal inherits twice, once from its parents’ genetic material and once from the mother’s microbiome with the aid of the father’s seminal microbiome, which helps determine the expression of the parental genes. The key point is that the failure of this latter inheritance in humans leads to the distinctive manifestations of functional FGID disorders including inflammation and gut motility disturbances. Furthermore, it seems likely that the critical microbiome–gut association occurs in the first few hours of independent life, in a process that we term handshaking. Note that even if obvious disease in childhood is avoided, the underlying disorders may intrude later in youth or adulthood with immune system disruption coexisting with gut–brain axis issues such as excessive weight gain and poor mental health. In principle, investigating and perhaps supplementing the maternal microbiota provide clinicians with an unprecedented opportunity to intervene in long-term disease processes, even before the child is born.

Azelaic Acid Regulates the Renin-Angiotensin System and Improves Colitis Based on Network Pharmacology and Experimentation

Inflammatory bowel disease (IBD), which encompasses Crohn's disease and ulcerative colitis, has a complicated etiology that might be brought on by metabolic dysbiosis. Previous metabonomic studies have found a correlation between decreased azelaic acid (AzA) and IBD. Herein, data from the Metabolomics Workbench showed that the content of AzA decreased in IBD patients (PR000639) and dextran sulfate sodium (DSS)-induced mice (PR000837). The effects of AzA on IBD were then examined using a DSS-induced mouse model, and the results demonstrated that AzA alleviated clinical activity, decreased pro-inflammatory cytokine production, and reduced CD4⁺CD25⁺Foxp3⁺Treg percentages in mesenteric lymph nodes. Through network pharmacology analysis, we discovered 99 candidate IBD-associated genes that are potentially regulated by AzA. After the enrichment analysis of the candidate genes, the renin-angiotensin system (RAS) pathway was one of the most substantially enriched pathways. Additionally, AzA reversed the increased expression of important RAS components (ACE, ACE2, and MAS1L) following DSS induction, suggesting that AzA exerts therapeutic effects possibly via the RAS pathway. This study suggests that AzA may be a promising drug for treating IBD.

Self-evidence-based digital care programme improves health-related quality of life in adults with a variety of autoimmune diseases and long COVID: a retrospective study

OBJECTIVE

To retrospectively investigate the feasibility and impact on health-related quality of life (HRQoL) of a digital care programme (DCP) designed to guide personalised diet and integrative interventions in a variety of autoimmune diseases and long COVID.

METHODS

Adults who participated in the DCP between April 2020 and June 2022, and for whom baseline (BL) and end-of-programme (EOP) Patient-Reported Outcomes Measurement Information System (PROMIS) scores were available, were included in this retrospective study. Changes from BL to EOP were calculated using standardised T-scores.

RESULTS

Two hundred two adults between 17 and 82 years old were included. Diagnoses included: rheumatoid arthritis (20.1%); long COVID (14.9%); psoriatic arthritis (10.9%); psoriasis (8.9%); systemic lupus erythematosus (6.4%); inflammatory bowel disease (5.9%); multiple sclerosis (5.9%); ankylosing spondylitis (5.4%) and other (23.3%). On average, individuals entered observations 7.6 times/day on 86% of programme days, attended 14 coach sessions and completed the programme in an average of 17.2 weeks. Statistically significant improvements were seen in all 10 PROMIS domains analysed. Individuals with higher severity of compromise at BL experienced greater average improvements than all-comers in all 10 PROMIS domains included.

CONCLUSION

An evidence-based DCP that uses patient data to help identify hidden symptom triggers and guide personalised dietary and other non-pharmacological interventions was associated with a high level of engagement and adherence and statistically significant, clinically meaningful improvements in HRQoL. Those with the least favourable PROMIS scores at BL experienced the greatest improvements.

Interactions of Nanomaterials with Gut Microbiota and Their Applications in Cancer Therapy

Cancer treatment is a challenge by its incredible complexity. As a key driver and player of cancer, gut microbiota influences the efficacy of cancer treatment. Modalities to manipulate gut microbiota have been reported to enhance antitumor efficacy in some cases. Nanomaterials (NMs) have been comprehensively applied in cancer diagnosis, imaging, and theranostics due to their unique and excellent properties, and their effectiveness is also influenced by gut microbiota. Nanotechnology is capable of targeting and manipulating gut microbiota, which offers massive opportunities to potentiate cancer treatment. Given the complexity of gut microbiota-host interactions, understanding NMs-gut interactions and NMs-gut microbiota interactions are important for applying nanotechnologies towards manipulating gut microbiota in cancer prevention and treatment. In this review, we provide an overview of NMs-gut interactions and NMs-gut microbiota interactions and highlight the influences of gut microbiota on the diagnosis and treatment effects of NMs, further illustrating the potential of nanotechnologies in cancer therapy. Investigation of the influences of NMs on cancer from the perspective of gut microbiota will boost the prospect of nanotechnology intervention of gut microbiota for cancer therapy.

Interplay between Phytochemicals and the Colonic Microbiota

Phytochemicals are natural compounds found in food ingredients with a variety of health-promoting properties. Phytochemicals improve host health through their direct systematic absorption into the circulation and modulation of the gut microbiota. The gut microbiota increases the bioactivity of phytochemicals and is a symbiotic partner whose composition and/or diversity is altered by phytochemicals and affects host health. In this review, the interactions of phytochemicals with the gut microbiota and their impact on human diseases are reviewed. We describe the role of intestinal microbial metabolites, including short-chain fatty acids, amino acid derivatives, and vitamins, from a therapeutic perspective. Next, phytochemical metabolites produced by the gut microbiota and the therapeutic effect of some selected metabolites are reviewed. Many phytochemicals are degraded by enzymes unique to the gut microbiota and act as signaling molecules in antioxidant, anti-inflammatory, anticancer, and metabolic pathways. Phytochemicals can ameliorate diseases by altering the composition and/or diversity of the gut microbiota, and they increase the abundance of some gut microbiota that produce beneficial substances. We also discuss the importance of investigating the interactions between phytochemicals and gut microbiota in controlled human studies.

The intratumoral microbiota: friend or foe?

The intratumoral microbiota has been recently identified as important in cancer evasion strategies. It can induce DNA damage, favor the epithelial-mesenchymal transition, inactivate drugs, polarize the immune system toward a protumorigenic profile, induce vascular reshaping and favor metastasis formation, and protect tumor cells from fluid shear stress during cell migration. However, recently also some positive effects of the intratumoral microbiota have been highlighted such as the activation of bacterial antigen-specific responses that could be harnessed to broaden not only the immune response to tumor antigens, but also the polarization of antitumorigenic responses. As in the gut, it is likely that the ratio between symbionts and pathobionts affects the outcome. More research is needed in this field to better understand this dual role.

Lupus Nephritis and Dysbiosis

Lupus nephritis (LN) is one of the most common and serious complications of systemic lupus erythematosus (SLE). The risk factors for developing LN by SLE patients are not fully understood. They are considered to be a mix of genetic and environmental variables, one of them being dysbiosis, proposed recently to interfere with autoimmunity. As of yet, the relations between the human microbiome, its genetic determinants, individual variability and clinical consequences remain to be established. One of the major obstacles in studying them is the magnitude of confounders, such as diet, drugs, infections or antibiotics use. They also make comparison between the studies extremely complicated. We reviewed the available evidence for the interplay between microbiome, dysbiosis and mechanisms triggering the autoimmune responses and potentially contributing to LN development. One such mechanism is the stimulation of autoimmune responses by bacterial metabolites that can mimic autoantigens and cause antibody production. These mimicking microbial antigens seem to be a promising target for future interventions.

Bacteria-Induced Colloidal Encapsulation for Probiotic Oral Delivery

Probiotic oral delivery has crucial implications in biomedical engineering, but its oral bioavailability remains unsatisfactory because of the limited survival and colonization of probiotics in the harsh gastrointestinal tract. Here, a bacteria-induced encapsulation strategy is achieved by assembling metastable colloids to enhance the oral bioavailability of probiotics. The colloids (NTc) composed of amino-modified poly-β-cyclodextrin and tannic acid are formed based on the balance of host-guest interaction-driven attraction and electrostatic repulsion between colloids. Negatively charged probiotics electrostatically attract positively charged NTc to break the balance and induce further assembly surrounding the probiotics. Through a facile one-step mixing, 97% of bacteria are rapidly encapsulated into NTc shells within 10 s, with a high utilization rate of feeding colloids of 91%. More importantly, we show that the compact, thick, and positively charged NTc shells synergistically endow the encapsulated probiotics with strong resistance against simulated gastric fluid with an excellent survival rate of up to 19%, 7500 times superior to the commercial enteric material L100. Moreover, owing to the dynamically noncovalent and self-adaptive nature of host-guest interactions, NTc shells support the proliferation of the encapsulated EcN comparable with that of the naked EcN. In vitro and in vivo experiments also confirm that the NTc-encapsulated probiotics possess durable intestinal adhesion, continuous proliferation activity, enhanced oral bioavailability, good oral biosafety, and excellent therapeutic efficacy in a colitis mouse model. This facile bacteria-induced colloidal encapsulation strategy may extend to various microbes as oral bioagents for treating various diseases.

Immunomodulatory Properties of Probiotics and Their Derived Bioactive Compounds

Immune system modulation is an intriguing part of scientific research. It is well established that the immune system plays a crucial role in orchestrating cellular and molecular key mediators, thus establishing a powerful defense barrier against infectious pathogens. Gut microbiota represent a complex community of approximately a hundred trillion microorganisms that live in the mammalian gastrointestinal (GI) tract, contributing to the maintenance of gut homeostasis via regulation of the innate and adaptive immune responses. However, impairment in the crosstalk between intestinal immunity and gut microbiota may reflect on detrimental health issues. In this context, many studies have indicated that probiotics and their bioactive compounds, such as bacteriocins and short chain fatty acids (SCFAs), display distinct immunomodulatory properties through which they suppress inflammation and enhance the restoration of microbial diversity in pathological states. This review highlights the fundamental features of probiotics, bacteriocins, and SCFAs, which make them ideal therapeutic agents for the amelioration of inflammatory and autoimmune diseases. It also describes their underlying mechanisms on gut microbiota modulation and emphasizes how they influence the function of immune cells involved in regulating gut homeostasis. Finally, it discusses the future perspectives and challenges of their administration to individuals.

Lupus pathogenesis and autoimmunity are exacerbated by high fat diet-induced obesity in MRL/lpr mice

OBJECTIVE

SLE is an autoimmune disease characterised by persistent inflammation and autoantibody production. Genetic predisposition and environmental factors such as a high-fat diet (HFD) may contribute to lupus development. However, the immune cell profile and gender difference in response to HFD in lupus have not been reported. Here we investigated the impact of HFD on lupus pathogenesis and autoimmunity using lupus-prone mice.

METHODS

Thirty male and 30 female MRL/lymphoproliferation (lpr) mice were fed with regular diet (RD) or HFD. Body weights were recorded weekly. SLE progression was monitored by skin lesion, urine protein, titres of antidouble-strand DNA (dsDNA) and ANA. At week 14, kidney and skin tissue sections were stained with H&E and periodic acid-Schiff to detect histological kidney index and skin score. Splenocytes were identified by immunofluorescence staining and flow cytometry.

RESULTS

HFD significantly increased body weight and lipid levels compared with RD (p<0.01). Skin lesions were observed in 55.6% of the HFD group compared with 11.1% of the RD group, with greater histopathological skin scores in the female HFD group (p<0.01). Although both male and female mice had higher serum IgG in the HFD group than in the RD group, only the male HFD group showed an increased trend in anti-dsDNA Ab and ANA titres. Kidney pathological changes in the HFD group were more severe in male mice than in female mice (p<0.05), detected by proteinuria, kidney index and glomerular cell proliferation. Significant increases of germinal centre B cells and T follicular helper cells were observed in the spleens of HFD mice (p<0.05).

CONCLUSION

HFD induced an accelerated and exacerbated lupus development and autoimmunity in MRL/lpr mice. Our results parallel many known clinical lupus phenotypes and sexual dimorphism in which male patients are likelier to have a severe disease (nephritis) than female lupus patients who may have a broader range of lupus symptoms.

Effect of tea catechins on gut microbiota in high fat diet-induced obese mice

BACKGROUND

Tea catechins have been shown to have beneficial effects on the alleviation of obesity, the prevention of diabetes, and the amelioration of metabolic syndrome. The purpose of the present work is to explore the underlying mechanisms linking the intestinal microbiota and anti-obesity benefits of green tea, oolong tea, and black tea catechins in C57BL/6J mice fed with a high-fat diet (HFD).

RESULTS

The results indicated that, after the dietary intake of three tea catechins, obesity and low-grade inflammation were significantly alleviated. Hepatic steatosis was prevented, and this was accompanied by the upregulation of the mRNA and protein expressions of hepatic peroxisome proliferator-activated receptor α (PPARα). Metagenomic analysis of fecal samples suggested that the three tea catechins similarly changed the microbiota in terms of overall structure, composition, and protein functions by regulating the metabolites, facilitating the generation of short-chain fatty acids (SCFAs), and repressing lipopolysaccharides.

CONCLUSION

The anti-obese properties of three tea catechins were partially mediated by their positive effect on gut microbiota, hepatic steatosis alleviation, and anti-inflammatory activity. © 2023 Society of Chemical Industry.

Small molecule metabolites: discovery of biomarkers and therapeutic targets

Metabolic abnormalities lead to the dysfunction of metabolic pathways and metabolite accumulation or deficiency which is well-recognized hallmarks of diseases. Metabolite signatures that have close proximity to subject's phenotypic informative dimension, are useful for predicting diagnosis and prognosis of diseases as well as monitoring treatments. The lack of early biomarkers could lead to poor diagnosis and serious outcomes. Therefore, noninvasive diagnosis and monitoring methods with high specificity and selectivity are desperately needed. Small molecule metabolites-based metabolomics has become a specialized tool for metabolic biomarker and pathway analysis, for revealing possible mechanisms of human various diseases and deciphering therapeutic potentials. It could help identify functional biomarkers related to phenotypic variation and delineate biochemical pathways changes as early indicators of pathological dysfunction and damage prior to disease development. Recently, scientists have established a large number of metabolic profiles to reveal the underlying mechanisms and metabolic networks for therapeutic target exploration in biomedicine. This review summarized the metabolic analysis on the potential value of small-molecule candidate metabolites as biomarkers with clinical events, which may lead to better diagnosis, prognosis, drug screening and treatment. We also discuss challenges that need to be addressed to fuel the next wave of breakthroughs.

Versatility of bacterial outer membrane vesicles in regulating intestinal homeostasis

Outer membrane vesicles (OMVs) play vital roles in bacterial communication both intraspecifically and interspecifically. However, extracellular mechanisms of gut microbiota-derived OMVs in the intestine remain poorly understood. Here, we report that OMVs released from Akkermansia muciniphila are able to (i) restore disturbed balance of the gut microbiota by selectively promoting the proliferation of beneficial bacteria through membrane fusion, (ii) elicit mucosal immunoglobulin A response by translocating into Peyer's patches and subsequently activating B cells and dendritic cells, and (iii) maintain the integrity of the intestinal barrier by entering intestinal epithelial cells to stimulate the expressions of tight junctions and mucus. We demonstrate that transplantation of gut microbiota-associated OMVs to the intestine can alleviate colitis and enhance anti-programmed cell death protein 1 therapy against colorectal cancer by regulating intestinal homeostasis. This work discloses the importance of gut microbiota-derived OMVs in intestinal ecology, providing an alternative target for disease intervention and treatment.

The high dose of inulin exacerbated food allergy through the excess accumulation of short-chain fatty acids in a BABL/c mouse model

Inulin dietary supplement is conventionally beneficial to gut health and can potentially prevent food allergy (FA). This study aimed to determine how dietary inulin interventions at different doses affect the OVA-induced FA in a BALB/c mouse model. Although the middle dose of inulin (50 mg per mouse) showed the best therapeutic effect on FA, high-inulin supplementation (80 mg per mouse) provoked severe allergic and intestinal inflammatory responses, which were characterized by elevated serum allergic inflammation-related factor levels, dysfunctional gut barrier, unbalanced luminal pH value, decrease in intestinal antioxidant capacity, and disordered gut microecology. Moreover, profiling of SCFAs indicated that the high-inulin-induced excess accumulation of SCFAs in the colon was responsible for the gut immune disorders. Spearman correlation analysis unraveled that the featured bacterial taxa in the high-inulin-treated mice were Ruminococcaceae and Bifidobacterium, of which the relative abundance was negatively correlated with expression of tight junction proteins and improvement of T cell homeostasis, and positively correlated with levels of allergic inflammation-related indexes. Our work suggested that high-inulin dietary supplementation can be detrimental to allergic individuals and highlighted the importance for personalized use of inulin-type dietary supplements to safely improve human health.

IBD disease-modifying therapies: insights from emerging therapeutics

Inflammatory bowel disease (IBD) pathogenesis is associated with gut mucosal inflammation, epithelial damage, and dysbiosis leading to a dysregulated gut mucosal barrier. However, the extent and underlying mechanisms remain largely unknown. Current treatment regimens have focused mainly on treating IBD symptoms; however, such treatment strategies do not address mucosal epithelial repair, barrier homeostasis, or intestinal dysbiosis. Although attempts have been made to identify new therapeutic modalities to enhance gut barrier functions, these are at an early developmental stage and have not been wholly successful. We review conventional therapies, the possible relevant role of gut barrier-protecting agents, and biomaterial strategies relating to combination therapies that may pave the way towards developing new therapeutic approaches for IBD.

Herba Origani alleviated DSS-induced ulcerative colitis in mice through remolding gut microbiota to regulate bile acid and short-chain fatty acid metabolisms

This study aimed to investigate the protective effect of Herba Origani, the dried whole herb of Origanum vulgare L., on dextran sodium sulfate (DSS)-induced ulcerative colitis in mice and explore its mechanisms of action through analyzing the intestinal microbiota in cecum contents and metabolites in colonic tissues. HOEP alleviated colitis symptoms, colonic inflammation and pathological injury as well as repaired intestinal barrier function in DSS-induced UC mice. The intestinal microbiota analysis showed that HOEP restored the gut microbiota dysbiosis in DSS-treated mice by increasing the alpha diversity of the intestinal microbiota, increasing the abundance of the Bacteroidota community and adjusting short-chain fatty acids (SCFAs), which maintain mucosal immunity and intestinal barrier. Metabolomic analysis revealed that HOEP promoted bile acids absorption and regulated bile acids metabolism in the intestine, thereby maintaining intestinal mucosal immune homeostasis. In addition, HOEP might also regulate the intestinal immune system through the phosphatidylinositol signaling system. These findings suggested that HOEP exerted promising protection against DSS-induced ulcerative mice through remolding gut microbiota to regulate bile acid and SCFA metabolism, and that HOEP have a potential to be utilized for the treatment of inflammatory intestinal diseases.

The Role of Microbiota-Derived Vitamins in Immune Homeostasis and Enhancing Cancer Immunotherapy

Not all cancer patients who receive immunotherapy respond positively and emerging evidence suggests that the gut microbiota may be linked to treatment efficacy. Though mechanisms of microbial contributions to the immune response have been postulated, one likely function is the supply of basic co-factors to the host including selected vitamins. Bacteria, fungi, and plants can produce their own vitamins, whereas humans primarily obtain vitamins from exogenous sources, yet despite the significance of microbial-derived vitamins as crucial immune system modulators, the microbiota is an overlooked source of these nutrients in humans. Microbial-derived vitamins are often shared by gut bacteria, stabilizing bioenergetic pathways amongst microbial communities. Compositional changes in gut microbiota can affect metabolic pathways that alter immune function. Similarly, the immune system plays a pivotal role in maintaining the gut microbiota, which parenthetically affects vitamin biosynthesis. Here we elucidate the immune-interactive mechanisms underlying the effects of these microbially derived vitamins and how they can potentially enhance the activity of immunotherapies in cancer.

Antibiotics-induced dysbiosis in gut microbiota affects bumblebee health via regulating host amino acid metabolism

The gut bacteria can provide nutrition for the host, and regulate host physiological functions and host behavior. In this study, we specifically examined the important roles of free amino acids in the gut microbiota-host interaction. Bumblebees were treated with different concentrations of antibiotics (ampicillin combined with low/high concentrations of tetracycline). Then the effect of antibiotic treatments on the host body weight, gut microbiota, and the free amino acid profiles in the hindgut, hemolymph and brain of bees was evaluated. The results showed that antibiotic treatments resulted in a significant decrease in the host body weight at 11 days of age, the total bacterial load and the abundance of Bifidobacterium bohemicum and Gilliamella apicola in the bumblebee's hindgut. Additionally, the higher the concentration of antibiotics (tetracycline), the greater their impact on the body weight and intestinal microbiota of bumblebees. Further, we found that antibiotic treatments caused changes of free amino acids in different tissues, especially in the hindgut and hemolymph, including particularly the decrease of several types of essential amino acids and branched-chain amino acids. Our results suggest that the gut microbiota may modulate the host growth via specific essential amino acids and branched-chain amino acids, which further reveals the crucial roles of free amino acids in the gut microbiota-host interplay.

Intrinsic STING Switches off Pathogenetic Programs of Th1 Cells to Inhibit Colitis

BACKGROUND & AIMS

T helper 1 (Th1) effector cells are implicated in inflammatory bowel disease. The stimulator of interferon genes (STING), an intracellular DNA sensor, has been shown to regulate infection and various cancers. However, whether and how intrinsic STING signaling in Th1 cells regulates colitis is still unknown.

METHODS

Dextran sodium sulfate-induced colitis and wild-type/STING-deficient CD4+T cell adoptive transfer models were used to analyze the role of STING in regulating colitis. The effect of STING on Th1 cells was determined by flow cytometry, RNA sequencing, metabolic assays, and mitochondrial functions. 16S ribosomal RNA sequencing and germ-free mice were used to investigate whether the microbiota were involved. The in vivo effect of STING agonist in murine colitis was determined. The expression and role of STING in human T cells were also determined.

RESULTS

Activation of STING transformed proinflammatory IFNγ+Th1 cells into IL-10+IFNγ+Th1 cells, which were dramatically less pathogenic in inducing colitis. STING promoted Th1 interleukin (IL)-10 production by inducing STAT3 translocation into nuclear and mitochondria, which promoted Blimp1 expression and mitochondrial oxidation, respectively. Blockade of glucose or glutamine-derived oxidation, but not lipid-derived oxidation, suppressed STING induction of IL-10. Gut microbiota were changed in STING-/- mice, but the altered microbiota did not mediate STING effects on intestinal CD4+T cell production of IL-10. Translationally, STING agonists suppressed both acute and chronic colitis. Intestinal STING+ CD4+T cells were increased in inflammatory bowel disease patients, and STING agonists upregulated IL-10 production in human CD4+T cells.

CONCLUSIONS

These findings establish a crucial role of T cell-intrinsic STING in switching off the pathogenic programs of Th1 cells in intestinal inflammation.

Gut Microbial Metabolites on Host Immune Responses in Health and Disease

Intestinal microorganisms interact with various immune cells and are involved in gut homeostasis and immune regulation. Although many studies have discussed the roles of the microorganisms themselves, interest in the effector function of their metabolites is increasing. The metabolic processes of these molecules provide important clues to the existence and function of gut microbes. The interrelationship between metabolites and T lymphocytes in particular plays a significant role in adaptive immune functions. Our current review focuses on 3 groups of metabolites: short-chain fatty acids, bile acids metabolites, and polyamines. We collated the findings of several studies on the transformation and production of these metabolites by gut microbes and explained their immunological roles. Specifically, we summarized the reports on changes in mucosal immune homeostasis represented by the Tregs and Th17 cells balance. The relationship between specific metabolites and diseases was also analyzed through latest studies. Thus, this review highlights microbial metabolites as the hidden treasure having potential diagnostic markers and therapeutic targets through a comprehensive understanding of the gut-immune interaction.

Strategizing the human microbiome for small molecules: Approaches and perspectives

Studies of the human microbiome are providing a deeper understanding of its significance to human health, and increasing evidence links the microbiota with several diseases. Nevertheless, the exact mechanisms involved in human-microbe interactions are mostly undefined. The genomic potential of the human microbiome to biosynthesize distinct molecules outmatches its known chemical space, and small-molecule discovery in this context remains in its infancy. The profiling of microbiome-derived small molecules and their contextualization through cause-effect mechanistic studies may provide a better understanding of host-microbe interactions, guide new therapeutic interventions, and modulate microbiome-based therapies. This review describes the advances, approaches, and allied challenges in mining new microbial scaffolds from the human microbiome using genomic, microbe cultivation, and chemical analytic platforms. In the future, the complete biological characterization of a single microbe-derived molecule that has a specific therapeutic application could resolve the current limitations of microbiota-modulating therapies.

A single-cell map of peripheral alterations after FMT treatment in patients with systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is characterized by loss of self-tolerance and persistent self-aggression, sustained chronic inflammation, production of autoantibodies and multi-system damage, and is largely incurable to date. The gut microbiota and its metabolites, now recognized as crucial environmental triggers of local/systemic immune reactions, have been implicated in the development and progression of SLE. Fecal microbiota transplantation (FMT) is restoration of disturbed microbiota by transplanting foreign gut microbiota from healthy individuals into the gastrointestinal tract of diseased individuals. Our previous clinical trial suggests that FMT is a potentially safe and effective treatment for SLE. In order to elucidate the potential effect of FMT on peripheral immune cells of patients with SLE, we collected PBMCs (n = 30) of 13 SLE patients who participated in the clinical trial before and after the FMT-treatment, and performed single-cell RNA sequencing. The results first revealed that peripheral T lymphocytes of SLE patients decreased and NK cells increased after the FMT treatment. Then, sub-clustering analysis discovered that total CD4⁺ T cells highly expressed genes of IL7R, CD28, and CD8⁺ T cells highly expressed genes of GZMH and NKG7 after FMT treatment. Moreover, FMT treatment reduced the expression of interferon-related genes (IRGs) in CD4⁺ T, CD8⁺ T, DP, NK, and B cells of SLE patients. More importantly, interferon-related pathways were more enriched in cells of the FMT non-responder group, and further the interferon genes expression of lymphocytes and myeloid cells was negatively correlated with the efficiency of FMT treatment. Collectively, our data identified various immunophenotypic and associated gene set changes following FMT treatment, illustrating the heterogeneity of response to FMT treatment in SLE.

Discussion on the common controversies of Helicobacter pylori infection

BACKGROUND

Helicobacter pylori ( H. pylori ) can persistently colonize on the gastric mucosa after infection and cause gastritis, atrophy, metaplasia, and even gastric cancer (GC).

METHODS

Therefore, the detection and eradication of H. pylori are the prerequisite.

RESULTS

Clinically, there are some controversial issues, such as why H. pylori infection is persistent, why it translocases along with the lesser curvature of the stomach, why there is oxyntic antralization, what the immunological characteristic of gastric chronic inflammation caused by H. pylori is, whether H. pylori infection is associated with extra-gastric diseases, whether chronic atrophic gastritis (CAG) is reversible, and what the potential problems are after H. pylori eradication. What are the possible answers?

CONCLUSION

In the review, we will discuss these issues from the attachment to eradication in detail.

Metabolites from specific intestinal bacteria in vivo fermenting Lycium barbarum polysaccharide improve collagenous arthritis in rats

Rheumatoid arthritis (RA) is an autoimmune disease affected patients' quality of life severely. Our previous study found Lycium barbarum polysaccharide (LBP) alleviated RA, but it remains unknown whether gut microbiota is necessary for the alleviation. Here, RA models were established in rats with microbiota and rats treated by antibiotic cocktail, and LBP was applied for the intervention on rats. The biochemical test, 16S rDNA sequencing and metabolome analysis were applied to analyze the effects of LBP on gut microbiota, their metabolites and hosts. Results showed the LBP intervention improved RA by inhibiting pro-inflammatory cytokines IL-1α, IL-1β, TNF-α and IL-6 only in rats with microbiota, but not in pseudo-germ-free rats. The abundance of specific bacteria, including Romboutsia, Lactobacillus, Turicibacter, Clostridium_sensu_stricto_1, Faecalibacterium and Adlercreutzia, and several metabolites, including O-desmethylangolensin, 3-hydroxydodecanedioic acid, N-formyl-L-methionine, suberic acid, (S)-oleuropeic acid, prolyl-histidine, 13,14-dihydro PGF-1a, (R)-pelletierine and short-chain fatty acids increased only in RA rats with microbiota after the intervention. Our results suggest that intestinal bacteria are necessary for LBP alleviating RA alleviation. The fermentation metabolite acts on the host instead of LBP itself, which may be the reason for the improvement of RA.

Effects of low protein diet with a balanced amino acid pattern on growth performance, meat quality and cecal microflora of finishing pigs

BACKGROUND

The present study aimed to investigate the effects of low protein diets balanced with four amino acids on growth performance, meat quality and cecal microflora of finishing pigs. Fifty-four healthy hybrid barrows (Duroc × Landrace × Yorkshire) with an average body weight of 70.12 ± 4.03 kg were randomly assigned to one of the three dietary treatments with six replicate pens per treatment (three barrows per pen). The three dietary treatments included a normal protein diet (NP), a low protein diet (LP) and a very low protein diet (VLP).

RESULTS

The average daily gain, average daily feed intake and feed conversion ratio of pigs were not significantly changed with the LP and VLP diets compared to the NP diet (P > 0.05). The water holding capacity and shear force of longissimus dorsi muscle were decreased, whereas the intramuscular fat content of the longissimus dorsi muscle was increased (P < 0.05) in pigs fed with the LP and VLP diets compared to the NP diet. The contents of saturated fatty acids in muscle were decreased (P < 0.05), whereas the content of polyunsaturated fatty acids in muscle was increased (P < 0.01) with the VLP diet compared to the NP diet. The contents of histamine, spermidine, spermine and tyramine of muscle were decreased with the VLP diet compared to the NP diet (P < 0.05). The relative abundance of Turicibacter, Terrisporobacter, Clostridium_sensu_stricto_1 and UCG-005 was higher (P < 0.05), whereas the relative abundance of Lactobacillus and Streptococcus was lower (P < 0.05) in pigs fed with the LP and VLP diets compared to the NP diet. Based on the correlation of cecal microbiota and cecal biogenic amine, the contents of tyramine, spermidine and histamine were negatively correlated with the abundance of Terrisporobacter (P < 0.01) and the content of histamine was positively correlated with the abundance of Lactobacillus (P < 0.01).

CONCLUSION

Balanced with four essential amino acids, the VLP diet with crude protein levels decreased by > 4% increased the intramuscular fat content, changed the fatty acid and amino acid composition of longissimus dorsi muscle and the profile of cecum microbiota, and reduced the content of cecum bioamine, with no negative effect on the growth performance of pigs. © 2022 Society of Chemical Industry.

Gut Microbial-Derived Metabolites as Immune Modulators of T Helper 17 and Regulatory T Cells

The gut microbiota and its derived metabolites greatly impact the host immune system, both innate and adaptive responses. Gut dysbiosis and altered levels of microbiota-derived metabolites have been described in several immune-related and immune-mediated diseases such as intestinal bowel disease, multiple sclerosis, or colorectal cancer. Gut microbial-derived metabolites are synthesized from dietary compounds ingested by the host or host-produced metabolites, and additionally, some bacterial products can be synthesized de novo. In this review, we focus on the two first metabolites families including short-chain fatty acids, indole metabolites, polyamines, choline-derived compounds, and secondary bile acids. They all have been described as immunoregulatory molecules that specifically affect the adaptive immune system and T helper 17 and regulatory T cells. We discuss the mechanisms of action and the consequences in health and diseases related to these gut microbial-derived metabolites. Finally, we propose that the exogenous administration of these molecules or other compounds that bind to their immunoregulatory receptors in a homologous manner could be considered therapeutic approaches.

Heptadecanoic acid and pentadecanoic acid crosstalk with fecal-derived gut microbiota are potential non-invasive biomarkers for chronic atrophic gastritis

Background

Chronic atrophic gastritis (CAG), premalignant lesions of gastric cancer (GC), greatly increases the risk of GC. Gastroscopy with tissue biopsy is the most commonly used technology for CAG diagnosis. However, due to the invasive nature, both ordinary gastroscope and painless gastroscope result in a certain degree of injury to the esophagus as well as inducing psychological pressure on patients. In addition, patients need fast for at least half a day and take laxatives.

Methods

In this study, fecal metabolites and microbiota profiles were detected by metabolomics and 16S rRNA V4-V5 region sequencing.

Results

Alteration of fecal metabolites and microbiota profiles was found in CAG patients, compared with healthy volunteers. To identify the most relevant features, 7 fecal metabolites and 4 microbiota were selected by random forest (RF), from A and B sample sets, respectively. Furthermore, we constructed support vector machines (SVM) classifification model using 7 fecal metabolites or 4 gut microbes, or 7 fecal metabolites with 4 gut microbes, respectively, on C sample set. The accuracy of classifification model was 0.714, 0.857, 0.857, respectively, and the AUC was 0.71, 0.88, 0.9, respectively. In C sample set, Spearman's rank correlation analysis demonstrated heptadecanoic acid and pentadecanoic acid were signifificantly negatively correlated to Erysipelotrichaceae_UCG-003 and Haemophilus, respectively. We constructed SVM classifification model using 2 correlated fecal metabolites and 2 correlated gut microbes on C sample set. The accuracy of classification model was 0.857, and the AUC was 0.88.

Conclusion

Therefore, heptadecanoic acid and pentadecanoic acid, crosstalk with fecal-derived gut microbiota namely Erysipelotrichaceae_UCG-003 and Haemophilus, are potential non-invasive biomarkers for CAG diagnosis.

Effect of Echinacea on gut microbiota of immunosuppressed ducks

Introduction

Immunosuppression puts animals in a susceptible state and disrupts the balance of intestinal flora, which can increase the risk of disease and cause serious harm to the farm. Echinacea can exert its immunomodulatory effect in various ways, but its influence on intestinal flora is unclear.

Methods

Therefore, we investigated the effect of Echinacea extract (EE) on gut microbiota in immunosuppressed ducks by 16s-RNA sequencing in this experiment.

Results

The results showed that EE significantly improved the weight gain of immunosuppressed ducks (p<0.001). It also increased the immune organ index (p<0.01) and upregulated the levels of TNF-α and IFN-γ (p<0.05) as well as IL-2 in the serum. The lesions of the bursa were evident compared to the spleen and thymus. After treatment in the EE group, the lymphocyte count of the bursa returned to healthy levels and the lesions were significantly improved. The diversity analysis showed that neither of the alpha-diversity indices showed a significant difference (p>0.05). However, the EE group had a trend closer to the healthy group compared to the M group. β-diversity analysis revealed a high degree of sample separation between the healthy and immunosuppressed groups. The sequencing result showed a significantly higher relative abundance of Prevotella and Prevotella_UCG_001 in the dexamethasone-treated group, which could be potential biomarkers of dexamethasone-induced immunosuppression. EE increased the relative abundance of Akkermansia, Bacteroides, and Alistipes and significantly decreased the relative abundance of Megamonas, Streptococcus, and Enterococcus (p<0.05).

Conclusion

The results showed that Echinacea extract improves the development of immunosuppressed ducks and modulates intestinal immune function by increasing the abundance of beneficial bacterial genera in the intestine.

Probiotic powder ameliorates colorectal cancer by regulating Bifidobacterium animalis, Clostridium cocleatum, and immune cell composition

Based on the relationship between the gut microbiota and colorectal cancer, we developed a new probiotic powder for treatment of colorectal cancer. Initially, we evaluated the effect of the probiotic powder on CRC using hematoxylin and eosin staining, and evaluated mouse survival rate and tumor size. We then investigated the effects of the probiotic powder on the gut microbiota, immune cells, and apoptotic proteins using 16S rDNA sequencing, flow cytometry, and western blot, respectively. The results showed that the probiotic powder improved the intestinal barrier integrity, survival rate, and reduced tumor size in CRC mice. This effect was associated with changes in the gut microbiota. Specifically, the probiotic powder increased the abundance of Bifidobacterium animalis and reduced the abundance of Clostridium cocleatum. In addition, the probiotic powder resulted in decreased numbers of CD4+ Foxp3+ Treg cells, increased numbers of IFN-γ+ CD8+ T cells and CD4+ IL-4+ Th2 cells, decreased expression of the TIGIT in CD4+ IL-4+ Th2 cells, and increased numbers of CD19+ GL-7+ B cells. Furthermore, the expression of the pro-apoptotic protein BAX was significantly increased in tumor tissues in response to the probiotic powder. In summary, the probiotic powder ameliorated CRC by regulating the gut microbiota, reducing Treg cell abundance, promoting the number of IFN-γ+ CD8+ T cells, increasing Th2 cell abundance, inhibiting the expression of TIGIT in Th2 cells, and increasing B cell abundance in the immune microenvironment of CRC, thereby increasing the expression of BAX in CRC.

Elucidating a fresh perspective on the interplay between exosomes and rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by chronic synovitis and the destruction of bones and joints. Exosomes are nanoscale lipid membrane vesicles originating from multivesicular bodies and are used as a vital means of intercellular communication. Both exosomes and the microbial community are essential in RA pathogenesis. Multiple types of exosomes from different origins have been demonstrated to have effects on various immune cells through distinct mechanisms in RA, which depend on the specific cargo carried by the exosomes. Tens of thousands of microorganisms exist in the human intestinal system. Microorganisms exert various physiological and pathological effects on the host directly or through their metabolites. Gut microbe-derived exosomes are being studied in the field of liver disease; however, information on their role in the context of RA is still limited. Gut microbe-derived exosomes may enhance autoimmunity by altering intestinal permeability and transporting cargo to the extraintestinal system. Therefore, we performed a comprehensive literature review on the latest progress on exosomes in RA and provided an outlook on the potential role of microbe-derived exosomes as emerging players in clinical and translational research on RA. This review aimed to provide a theoretical basis for developing new clinical targets for RA therapy.

Gut microbiota composition in patients with advanced malignancies experiencing immune-related adverse events

Introduction

The gut microbiota is implicated in the occurrence and severity of immune-related adverse events (irAEs), but the role it plays as well as its causal relationship with irAEs has yet to be established.

Methods

From May 2020 to August 2021, 93 fecal samples were prospectively collected from 37 patients with advanced thoracic cancers treated with anti-PD-1 therapy, and 61 samples were collected from 33 patients with various cancers developing different irAEs. 16S rDNA amplicon sequencing was performed. Antibiotic-treated mice underwent fecal microbiota transplantation (FMT) with samples from patients with and without colitic irAEs.

Results

Microbiota composition was significantly different in patients with and without irAEs (P=0.001) and with and without colitic-type irAEs (P=0.003). Bifidobacterium, Faecalibacterium, and Agathobacter were less abundant and Erysipelatoclostridium more abundant in irAE patients, while Bacteroides and Bifidobacterium were less abundant and Enterococcus more abundant in colitis-type irAE patients. Major butyrate-producing bacteria were also less abundant in patients with irAEs than those without (P=0.007) and in colitic vs. non-colitic irAE patients (P=0.018). An irAE prediction model had an AUC of 86.4% in training and 91.7% in testing. Immune-related colitis was more common in colitic-irAE-FMT (3/9) than non-irAE-FMT mice (0/9).

Conclusions

The gut microbiota is important in dictating irAE occurrence and type, especially for immune-related colitis, possibly by modulating metabolic pathways.

The heightened importance of the microbiome in cancer immunotherapy

The human microbiome is recognized as a key factor in health and disease. This has been further corroborated by identifying changes in microbiome composition and function as a novel hallmark in cancer. These effects are exerted through microbiome interactions with host cells, impacting a wide variety of developmental and physiological processes. In this review, we discuss some of the latest findings on how the bacterial component of the microbiome can influence outcomes for different cancer immunotherapy modalities, highlighting identified mechanisms of action. We also address the clinical efforts to utilize this knowledge to achieve better responses to immunotherapy. A refined understanding of microbiome variations in patients and microbiome-host interactions with cancer therapies is essential to realize optimal clinical responses.

Gut Microbiota Alterations and Primary Glomerulonephritis in Children: A Review

The article summarizes the current evidence on the impact of microbiota alterations on immune-mediated primary glomerulonephritis in children. In particular, the focus is on the link between dysbiosis and the onset or recurrence of idiopathic nephrotic syndrome, immunoglobulin A nephropathy, and membranous nephropathy. The aim is to describe possible pathomechanisms, differences in gut microbiota composition between pediatric patients and healthy controls, and possible usage of microbiota manipulations in supportive therapy. On this basis, we attempt to indicate directions for further research in that field.

Voglibose Regulates the Secretion of GLP-1 Accompanied by Amelioration of Ileal Inflammatory Damage and Endoplasmic Reticulum Stress in Diabetic KKAy Mice

Voglibose is an α-glycosidase inhibitor that improves postprandial hyperglycemia and increases glucagon-like peptide-1 (GLP-1) secretion in patients with type 2 diabetes. Recently, there has been increasing interest in the anti-inflammatory effects of voglibose on the intestine, but the underlying mechanism is not clear. This study evaluated the effects and mechanisms of voglibose on glycemic control and intestinal inflammation. Type 2 diabetic KKAy mice were treated with voglibose (1 mg/kg) by oral gavage once daily. After 8 weeks, glucose metabolism, levels of short-chain fatty acids (SCFAs), systematic inflammatory factors, intestinal integrity and inflammation were evaluated using hematoxylin and eosin staining, immunohistochemistry, immunofluorescence and Western blot analysis. Voglibose ameliorated glucose metabolism by enhancing basal- and glucose-dependent GLP-1 secretion. Several beneficial SCFAs, such as acetic acid and propionic acid, were increased by voglibose in the fecal sample. Additionally, voglibose notably decreased the proportion of pro-inflammatory macrophages and the expression of nuclear factor kappa B but increased the expression of tight junction proteins in the ileum, thus markedly improving intestinal inflammatory damage and reducing the systematic inflammatory factors. Ileal genomics and protein validation suggested that voglibose attenuated inositol-requiring protein 1α-X-box binding protein 1-mediated endoplasmic reticulum stress (ERS). Together, these results showed that voglibose enhanced the secretion of GLP-1, which contributed to the glycemic control in KKAy mice at least in part by regulating intestinal inflammation and the expression of ERS factors.

Immune mechanism of gut microbiota and its metabolites in the occurrence and development of cardiovascular diseases

The risk of cardiovascular disease (CVD) is associated with unusual changes in the human gut microbiota, most commonly coronary atherosclerotic heart disease, hypertension, and heart failure. Immune mechanisms maintain a dynamic balance between the gut microbiota and the host immune system. When one side changes and the balance is disrupted, different degrees of damage are inflicted on the host and a diseased state gradually develops over time. This review summarizes the immune mechanism of the gut microbiota and its metabolites in the occurrence of common CVDs, discusses the relationship between gut-heart axis dysfunction and the progression of CVD, and lists the currently effective methods of regulating the gut microbiota for the treatment of CVDs.

Gut Microbiota Alterations in Trace Amine-Associated Receptor 9 (TAAR9) Knockout Rats

Trace amine-associated receptors (TAAR1-TAAR9) are a family of G-protein-coupled monoaminergic receptors which might have great pharmacological potential. It has now been well established that TAAR1 plays an important role in the central nervous system. Interestingly, deletion of TAAR9 in rats leads to alterations in the periphery. Previously, we found that knockout of TAAR9 in rats (TAAR9-KO rats) decreased low-density lipoprotein cholesterol levels in the blood. TAAR9 was also identified in intestinal tissues, and it is known that it responds to polyamines. To elucidate the role of TAAR9 in the intestinal epithelium, we analyzed TAAR9-co-expressed gene clusters in public data for cecum samples. As identified by gene ontology enrichment analysis, in the intestine, TAAR9 is co-expressed with genes involved in intestinal mucosa homeostasis and function, including cell organization, differentiation, and death. Additionally, TAAR9 was co-expressed with genes implicated in dopamine signaling, which may suggest a role for this receptor in the regulation of peripheral dopaminergic transmission. To further investigate how TAAR9 might be involved in colonic mucosal homeostasis, we analyzed the fecal microbiome composition in TAAR9-KO rats and their wild-type littermates. We identified a significant difference in the number of observed taxa between the microbiome of TAAR9-KO and wild-type rats. In TAAR9-KO rats, the gut microbial community became more variable compared with the wild-type rats. Furthermore, it was found that the family Saccharimonadaceae, which is one of the top 10 most abundant families in TAAR9-KO rat feces, is almost completely absent in wild-type animal fecal samples. Taken together, these data indicate a role of TAAR9 in intestinal function.

Oral Microbiota and Tumor-A New Perspective of Tumor Pathogenesis

Microorganisms have long been known to play key roles in the initiation and development of tumors. The oral microbiota and tumorigenesis have been linked in epidemiological research relating to molecular pathology. Notably, some bacteria can impact distal tumors by their gastrointestinal or blood-borne transmission under pathological circumstances. Certain bacteria drive tumorigenesis and progression through direct or indirect immune system actions. This review systemically discusses the recent advances in the field of oral microecology and tumor, including the oncogenic role of oral microbial abnormalities and various potential carcinogenesis mechanisms (excessive inflammatory response, host immunosuppression, anti-apoptotic activity, and carcinogen secretion) to introduce future directions for effective tumor prevention.

Effects of gut microbiota on immune responses and immunotherapy in colorectal cancer

Accumulating evidence suggests that gut microbial dysbiosis is implicated in colorectal cancer (CRC) initiation and progression through interaction with host immune system. Given the intimate relationship between the gut microbiota and the antitumor immune responses, the microbiota has proven to be effective targets in modulating immunotherapy responses of preclinical CRC models. However, the proposed putative mechanisms of how these bacteria affect immune responses and immunotherapy efficacy remains obscure. In this review, we summarize recent findings of clinical gut microbial dysbiosis in CRC patients, the reciprocal interactions between gut microbiota and the innate and/or the adaptive immune system, as well as the effect of gut microbiota on immunotherapy response in CRC. Increased understanding of the gut microbiota-immune system interactions will benefit the rational application of microbiota to the clinical promising biomarker or therapeutic strategy as a cancer immunotherapy adjuvant.

The multisensory regulation of unconventional T cell homeostasis

Unconventional T cells typically group γδ T cells, invariant Natural Killer T cells (NKT) and Mucosal Associated Invariant T (MAIT) cells. With their pre-activated status and biased tropism for non-lymphoid organs, they provide a rapid (innate-like) and efficient first line of defense against pathogens at strategical barrier sites, while they can also trigger chronic inflammation, and unexpectedly contribute to steady state physiology. Thus, a tight control of their homeostasis is critical to maintain tissue integrity. In this review, we discuss the recent advances of our understanding of the factors, from neuroimmune to inflammatory regulators, shaping the size and functional properties of unconventional T cell subsets in non-lymphoid organs. We present a general overview of the mechanisms common to these populations, while also acknowledging specific aspects of their diversity. We mainly focus on their maintenance at steady state and upon inflammation, highlighting some key unresolved issues and raising upcoming technical, fundamental and translational challenges.

A narrative review of the moderating effects and repercussion of exercise intervention on osteoporosis: ingenious involvement of gut microbiota and its metabolites

Osteoporosis (OP) is a systemic bone disease characterized by the decreased bone mass and destruction of bone microstructure, which tends to result in the enhanced bone fragility and related fractures, as well as high disability rate and mortality. Exercise is one of the most common, reliable and cost-effective interventions for the prevention and treatment of OP currently, and numerous studies have revealed the close association between gut microbiota (GM) and bone metabolism recently. Moreover, exercise can alter the structure, composition and abundance of GM, and further influence the body health via GM and its metabolites, and the changes of GM also depend on the choice of exercise modes. Herein, combined with relevant studies and based on the inseparable relationship between exercise intervention-GM-OP, this review is aimed to discuss the moderating effects and potential mechanisms of exercise intervention on GM and bone metabolism, as well as the interaction between them.

The Effect of Indole-3-Lactic Acid from Lactiplantibacillus plantarum ZJ316 on Human Intestinal Microbiota In Vitro

Microbiota-derived tryptophan metabolites are essential signals for maintaining gut homeostasis, yet the potential contribution to modulating gut microbiota has been rarely investigated. In this study, Lactiplantibacillus plantarum ZJ316 (CCTCC No. M 208077) with a high production (43.14 μg/mL) of indole-3-lactic acid (ILA) was screened. ILA with 99.00% purity was prepared by macroporous resin, Sephadex G–25 and reversed-phase high-performance liquid chromatography. Purified ILA can effectively inhibit foodborne pathogens such as Salmonella spp., Staphylococcus spp., Escherichia coli and Listeria monocytogenes. In an in vitro model of the human gut microbiota, a medium-dose ILA (172 mg/L) intervention increased the average relative abundance of phyla Firmicutes and Bacteroidota by 9.27% and 15.38%, respectively, while Proteobacteria decreased by 14.36% after 24 h fermentation. At the genus level, the relative abundance of Bifidobacterium and Faecalibacterium significantly increased to 5.36 ± 2.31% and 2.19 ± 0.77% (p < 0.01), respectively. Escherichia and Phascolarctobacterium decreased to 16.41 ± 4.81% (p < 0.05) and 2.84 ± 1.02% (p < 0.05), respectively. Intestinal short-chain fatty acids, especially butyric acid, were significantly increased (2.98 ± 0.72 µmol/mL, p < 0.05) and positively correlated with Oscillospira and Collinsella. Overall, ILA has the potential to regulate the gut microbiota, and an in-depth understanding of the relationship between tryptophan metabolites and gut microbiota is needed in the future.

RhoB affects colitis through modulating cell signaling and intestinal microbiome

BACKGROUND

The pathogenesis of inflammatory bowel diseases (IBD) is multifactorial, and diagnostic and treatment strategies for IBD remain to be developed. RhoB regulates multiple cell functions; however, its role in colitis is unexplored.

RESULTS

Here, we found RhoB was dramatically increased in colon tissues of ulcerative colitis (UC) patients and mice with DSS-induced colitis. Compared with wild type mice, RhoB^+/- and RhoB^-/- mice developed milder DSS-induced colitis and increased goblet cell numbers and IEC proliferation. Decreased RhoB promoted goblet cell differentiation and epithelial regeneration through inhibiting Wnt signaling pathway and activating p38 MAPK signaling pathway. Moreover, increased SCFA-producing bacteria and SCFA concentrations were detected in intestinal microbiome of both RhoB^+/- and RhoB^-/- mice and upregulated SCFA receptor expression was also observed.

CONCLUSIONS

Taken together, a higher level of RhoB is associated with UC, which also contributes to UC development through modulating cell signaling and altering intestinal bacterial composition and metabolites. These observations suggest that RhoB has potential as a biomarker and a treatment target for UC. Video Abstract.

Detection of Intestinal Dysbiosis in Post-COVID-19 Patients One to Eight Months after Acute Disease Resolution

The intestinal microbiota plays an important role in the immune response against viral infections, modulating both innate and adaptive immune responses. The cytokine storm is associated with COVID-19 severity, and the patient's immune status is influenced by the intestinal microbiota in a gut-lung bidirectional interaction. In this study, we evaluate the intestinal microbiota of Brazilian patients in different post-COVID-19 periods, and correlate this with clinical data and the antibiotic therapy used during the acute phase. DNA extracted from stool samples was sequenced and total anti-SARS-CoV-2 antibodies and C-reactive protein were quantified. Compared with controls, there were significant differences in the microbiota diversity in post-COVID-19 patients, suggesting an intestinal dysbiosis even several months after acute disease resolution. Additionally, we detected some genera possibly associated with the post-COVID-19 dysbiosis, including Desulfovibrio, Haemophillus, Dialister, and Prevotella, in addition to decreased beneficial microbes, associated with antibiotic-induced dysbiosis, such as Bifidobacterium and Akkermansia. Therefore, our hypothesis is that dysbiosis and the indiscriminate use of antibiotics during the pandemic may be associated with post-COVID-19 clinical manifestations. In our study, 39% (n = 58) of patients reported symptoms, including fatigue, dyspnea, myalgia, alopecia, anxiety, memory loss, and depression. These data suggest that microbiota modulation may represent a target for recovery from acute COVID-19 and a therapeutic approach for post-COVID-19 sequelae.

The Effects of Physical Activity on the Gut Microbiota and the Gut–Brain Axis in Preclinical and Human Models: A Narrative Review

Increasing evidence supports the importance of the gut microbiota (GM) in regulating multiple functions related to host physical health and, more recently, through the gut–brain axis (GBA), mental health. Similarly, the literature on the impact of physical activity (PA), including exercise, on GM and GBA is growing. Therefore, this narrative review summarizes and critically appraises the existing literature that delves into the benefits or adverse effects produced by PA on physical and mental health status through modifications of the GM, highlighting differences and similarities between preclinical and human studies. The same exercise in animal models, whether performed voluntarily or forced, has different effects on the GM, just as, in humans, intense endurance exercise can have a negative influence. In humans and animals, only aerobic PA seems able to modify the composition of the GM, whereas cardiovascular fitness appears related to specific microbial taxa or metabolites that promote a state of physical health. The PA favors bacterial strains that can promote physical performance and that can induce beneficial changes in the brain. Currently, it seems useful to prioritize aerobic activities at a moderate and not prolonged intensity. There may be greater benefits if PA is undertaken from a young age and the effects on the GM seem to gradually disappear when the activity is stopped. The PA produces modifications in the GM that can mediate and induce mental health benefits.

Understanding Pathogenesis Intersects With Effective Treatment for Thyroid Eye Disease

CONTEXT

Thyroid eye disease (TED), a vision-threatening and disfiguring autoimmune process, has thwarted our efforts to understand its pathogenesis and develop effective and safe treatments. Recent scientific advances have facilitated improved treatment options.

OBJECTIVE

Review historically remote and recent advances in understanding TED.

DESIGN/SETTING/PARTICIPANTS

PubMed was scanned using search terms including thyroid-associated ophthalmopathy, thyroid eye disease, Graves' orbitopathy, autoimmune thyroid disease, and orbital inflammation.

MAIN OUTCOME MEASURES

Strength of scientific evidence, size, scope, and controls of clinical trials/observations.

RESULTS

Glucocorticoid steroids are widely prescribed systemic medical therapy. They can lessen inflammation-related manifestations of TED but fail to reliably reduce proptosis and diplopia, 2 major causes of morbidity. Other current therapies include mycophenolate, rituximab (anti-CD20 B cell-depleting monoclonal antibody), tocilizumab (interleukin-6 receptor antagonist), and teprotumumab (IGF-I receptor inhibitor). Several new therapeutic approaches have been proposed including targeting prostaglandin receptors, vascular endothelial growth factor, mTOR, and cholesterol pathways. Of potentially greater long-term importance are attempts to restore immune tolerance.

CONCLUSION

Despite their current wide use, steroids may no longer enjoy first-tier status for TED as more effective and better tolerated medical options become available. Multiple current and emerging therapies, the rationales for which are rooted in theoretical and experimental science, promise better options. These include teprotumumab, rituximab, and tocilizumab. Restoration of immune tolerance could ultimately become the most effective and safe medical management for TED.

Deferiprone has less benefits on gut microbiota and metabolites in high iron-diet induced iron overload thalassemic mice than in iron overload wild-type mice: A preclinical study

AIMS

This study aimed to investigate the changes in gut microbiota in iron-overload thalassemia and the roles of an iron chelator on gut dysbiosis/inflammation, and metabolites, including short-chain fatty acids (SCFAs) and trimethylamine N-oxide (TMAO).

MAIN METHODS

Adult male C57BL/6 mice both wild-type (WT: n = 15) and heterozygous β-thalassemia (BKO: n = 15) were fed on either a normal (ND: n = 5/group) or a high‑iron diet for four months (HFe: n = 10/group). HFe-treated WT and HFe-treated BKO groups were further subdivided into two subgroups and each subgroup given either vehicle (n = 5/subgroup) or deferiprone (n = 5/subgroup) during the last month. Gut microbiota profiles, gut barrier characteristics, levels of proinflammatory cytokines, and plasma SCFAs and TMAO were determined at the end of the study.

KEY FINDINGS

HFe-fed WT mice showed distinct gut microbiota profiles from those of ND-fed WT mice, whereas HFe-fed BKO mice showed slightly different gut microbiota profiles from ND-fed BKO. Gut inflammation and barrier disruption were found only in HFe-fed BKO mice, however, an increase in plasma TMAO levels and decreased levels of SCFAs were observed in both WT and BKO mice with HFe-feeding. Treatment with deferiprone, gut dysbiosis and disturbance of metabolites were attenuated in HFe-fed WT mice, but not in HFe-fed BKO mice. Increased Verrucomicrobia and Ruminococcaceae were associated with the beneficial effects of deferiprone.

SIGNIFICANCE

Iron-overload leads to gut dysbiosis/inflammation and disturbance of metabolites, and deferiprone alleviates those conditions more effectively in WT than in those that are thalassemic.

A balanced gut microbiota is essential to maintain health in captive sika deer

Certain animals harbor a high proportion of pathogens, particular the zoonotic pathogens, in their gut microbiome but are usually asymptomic; however, their carried pathogens may seriously threaten the public health. By understanding how the microbiome overcomes the negative effects of pathogens to maintain host health, we can develop novel solutions to control animal-mediated pathogen transmission including identification and application of beneficial microbes. Here, we analyzed the gut microbiota of 10 asymptomic captive sika deer individuals by full-length 16S rDNA sequencing. Twenty-nine known pathogens capable of infecting humans were identified, and the accumulated proportions of the identified pathogens were highly variable among individuals (2.33 to 39.94%). The relative abundances of several beneficial bacteria, including Lactobacillus and Bifidobacterium, were found to be positively correlated with the relative abundances of accumulated pathogens. Whole-genome metagenomic analysis revealed that the beneficial- and pathogenic-associated functions, such as genes involved in the synthesis of short chain fatty acids and virulence factors, were also positively correlated in the microbiome, indicating that the beneficial and pathogenic functions were maintained at a relatively balanced ratio. Furthermore, the bacteriophages that target the identified pathogens were found to be positively correlated with the pathogenic content in the microbiome. Several high-quality genomes of beneficial bacteria affiliated with Lactobacillus and Bifidobacterium and bacteriophages were recovered from the metagenomic data. Overall, this study provides novel insights into the interplay between beneficial and pathogenic content to ensure maintenance of a healthy gut microbiome, and also contributes to discovery of novel beneficial microbes and functions that control pathogens. KEY POINTS: • Certain asymptomic captive sika deer individuals harbor relatively high amounts of zoonotic pathogens. • The beneficial microbes and the beneficial functions are balanced with the pathogenic contents in the gut microbiome. • Several high-quality genomes of beneficial bacteria and bacteriophages are recovered by metagenomics.

Novel Sources of Bioactive Molecules: Gut Microbiome of Species Routinely Exposed to Microorganisms

Simple Summary

The majority of antibiotics available in the market are produced by bacteria isolated from soil. However, the low-hanging fruit has been picked; hence, there is a need to mine bacteria from unusual sources. With this in mind, it is important to note that animals and pests, such as cockroaches, snake, crocodiles, water monitor lizards, etc., come across pathogenic bacteria regularly, yet flourish in contaminated environments. These species must have developed methods to defend themselves against pathogens. Besides the immunity they may confer, bacteria associated with animals/pests may offer a potential source of novel antibacterial agents. This paper discusses the current knowledge of bacteria isolated from land and marine animals with antibacterial properties and proposes untapped sources for the isolation of bacteria to mine potentially novel antibiotic molecules.

Abstract

The development of novel bioactive molecules is urgently needed, especially with increasing fatalities occurring due to infections by bacteria and escalating numbers of multiple-drug-resistant bacteria. Several lines of evidence show that the gut microbiome of cockroaches, snakes, crocodiles, water monitor lizards, and other species may possess molecules that are bioactive. As these animals are routinely exposed to a variety of microorganisms in their natural environments, it is likely that they have developed methods to counter these microbes, which may be a contributing factor in their persistence on the planet for millions of years. In addition to the immune system, the gut microbiota of a host may thwart colonization of the gastro-intestine by pathogenic and/or foreign microorganisms through two mechanisms: (i) production of molecules with antibacterial potential targeting foreign microorganisms, or (ii) production of molecules that trigger host immunity targeting foreign microorganisms that penetrate the host. Herein, we discuss and deliberate on the current literature examining antibacterial activities that stem from the gut bacteria of animals such as crocodiles, cockroaches, and water monitor lizards, amongst other interesting species, which likely encounter a plethora of microorganisms in their natural environments. The overall aim is to unveil a potential library of novel bioactive molecules for the benefit of human health and for utilization against infectious diseases.