Colonic Contents Research Articles

CNSC-38. INFLUENCE OF AGE, IMMUNOREGULATORY IDO, AND IMMUNOTHERAPY ON THE MICROBIOME IN MICE WITH AN EXPERIMENTAL BRAIN TUMOR

Abstract OBJECTIVE This study aimed to determine how IDO and subject age impact the gut microbiome and microbial metabolites during immunotherapy for glioblastoma (GBM). METHODS Serum and colon contents were collected from young 16-20- or older adult 92-118-week-old wild-type (WT; C57BL/6), IDO knockout (IDOKO), and IDO enzyme null (H350A) mice analyzed for 16S rRNA gut microbiome composition and microbial-derived aromatic amino acid metabolites via LC/MS/MS. Fecal samples from young 7-8 or older adult 81-85 week-old WT mice with intracranial GL261 brain tumors treated with or without brain radiation (RT) and PD-1 mAb were also analyzed. RESULTS Young and old IDOKO and H350A mice demonstrated a unique gut microbiome signature with an elevated abundance of Bifidobacterium and Helicobacter (p<0.05) and a reduced abundance of Ventriosum and Sireaum compared to WT mice (p<0.001). Prevotellaceae, Muribaculum, Alistipes, Enterohabdus, Clostridia, and Akkermansia were different in IDOKO and H350A mice compared to WT - but only in old mice. Serum aryl-lactates including phenyllactate, indolelacatate, and 4-hydroxyphenyllactate were increased in IDOKO mice compared to WT and H350A mice (p<0.001) – again, only in old mice. Older adult WT mice with GL261 showed lower fecal aryl-lactates compared to younger counterparts. Treatment with RT + PD-1 mAb decreased phenyllactate levels in old but not young mice with GL261 (p<0.05). CONCLUSIONS There are IDO enzyme- and non-enzyme-dependent effects on gut microbiota composition and bioactive microbial aromatic amino acid metabolites. These data warrant further investigation into how microbial metabolism affects immunotherapy efficacy and brain tumor survival across the lifespan.

Protective effect of a cocktail of lactic acid bacteria on DSS-induced ulcerative colitis via activating the TGR5/PKA pathway

Ulcerative colitis (UC), a persistent intestinal disorder, is now considered a global disease. The present study was designed to investigate the alleviative effects of a cocktail of lactic acid bacteria (CLAB; Lactobacillus rhamnosus MP108, L. paracasei CCFM2711, Bifidobacterium animalis BB-115, and B. longum BLI-02) on UC and its mechanisms through a UC mouse model triggered by dextran sulfate sodium (DSS). The results indicated that CLAB improved colitis symptoms, intestinal pathologic damage, and intestinal barrier in mice. Moreover, CLAB attenuated colonic inflammatory responses in mice by remodeling the homeostasis between pro-inflammatory and anti-inflammatory cytokines. In addition, CLAB improved the structure of the gut microbiota and augmented the proportion of secondary bile acid-producing bacteria. Untargeted metabolomics analysis revealed that CLAB altered the metabolic profile of colonic contents and, importantly, increased the content of lithocholic acid (LCA). Further, CLAB activated the TGR5/PKA pathway via significantly upregulating the protein expression of TGR5, PKA, and p-CREB. Thus, CLAB alleviated UC, probably by increasing secondary bile acid-producing bacteria, resulting in increased levels of LCA, which in turn activated the TGR5/PKA pathway, thereby reducing the inflammatory response. The present study will offer a theoretical foundation for developing probiotic products to mitigate UC.

Cordycepin mitigates dextran sulfate sodium-induced colitis through improving gut microbiota composition and modulating Th1/Th2 and Th17/Treg balance

BackgroundImbalances in Th1/Th2 and Th17/Treg immune axes, coupled with disruptions in the gut microbiota (GM), play a pivotal role in the pathogenesis of inflammatory bowel disease (IBD). Cordycepin, a natural anti-inflammatory compound, holds promise in mitigating IBD by rebalancing these immune axes in conjunction with modulating the GM. The aim of this experiment is to investigate the potential of cordycepin in mitigating enteritis and elucidate the underlying mechanisms associated with its ameliorative effects on enteritis. MethodsOn the day of inducing experimental colitis with Dextran Sulfate Sodium (DSS), mice in the DSS + Cordycepin and Cordycepin groups received 50 mg/kg/day Cordycepin via intra-gastric administration (i.g.) for seven consecutive days, respectively. Mice in the DSS and control groups were treated with equal volumes of saline. On day 8, all mice were euthanized under pentobarbital sodium anesthesia. ResultsIn a DSS-induced colitis mouse model, Cordycepin treatment led to a significant reduction in the disease activity index (DAI), splenic weight, and colonic pathological injury while simultaneously improving body weight and colonic length. Furthermore, it positively impacted GM composition, resulting in decreased Th1 and Th17 cells, alongside an increase in Th2 and Treg cells. The contents of the mouse colon were extracted for microbial community analysis. Mouse blood was prepared into a single-cell suspension, and flow cytometry was used to assess the expressio of Treg, Th17, Th1, and Th2 immune cells. ConclusionsThese results underscored the effective intervention of cordycepin in ameliorating DSS-induced colitis by harmonizing the interplay between GM and immune homeostasis.

LC-MRM-MS-based lipidomics reveals differences in the digestion, absorption, and metabolism of phosphatidylcholines from Egg, Soy, and Krill in vivo

The acyl chain composition of dietary sources phosphatidylcholine (PC) is highly diverse. However, the effect of different PC intakes on the digestive products lysophosphatidylcholines (LPCs) and plasma metabolite species has not been elucidated. Here, LC-MRM-MS analysis was employed to identify and quantify 36 PC and 10 LPC molecular species in small intestinal contents, jejunum, plasma, and colonic contents within 12 h after administration of Egg-PC, Soy-PC, and Krill-PC. These results showed that the three PCs were rapidly hydrolyzed to LPCs within 0.5 h of reaching the small intestine, and the LPC species showed significant positive correlations with the corresponding fatty acid composition of the dietary PC. Notably, the abundance of plasma PUFA_PUFA PCs such as PC18:2_18:2 increased 5.8-fold after administration of Soy-PC for 2 h. Strikingly, administration of krill-PC for 2 h increased plasma LPC20:5 and PC16:0_20:5 by 23.6-fold and 26.6-fold, respectively, compared to 0 h, but the level of PC20:5_20:5 was low. In addition, correlation between the LPC species in small intestinal contents and plasma phospholipid species were analyzed, shedding light on the rules of re-esterification and absorption. These results could be useful for efficiently exploiting the nutritional functions of PCs with different acyl chains.

Dietary Bacteriophage Administration Alleviates Enterotoxigenic Escherichia coli-Induced Diarrhea and Intestinal Impairment through Regulating Intestinal Inflammation and Gut Microbiota in a Newly Weaned Mouse Model

This study aimed to investigate the effects of dietary bacteriophage administration on diarrhea and intestinal impairment induced by enterotoxigenic Escherichia coli (ETEC) in a newly weaned mouse model. Forty-four newly weaned C57BL/6 mice were divided into four treatment groups, where they were provided either the control diet or the bacteriophage-supplemented diet, with or without ETEC infection. The results show that the bacteriophage administration resulted in increased body weight, decreased diarrhea score, and improved jejunal histopathology in ETEC-infected mice. The bacteriophage administration enhanced the intestinal barrier function of the ETEC-infected mice, as indicated by the reduced serum DAO level and the increased expression of Claudin-1, Occludin, and ZO-1 at both the mRNA and protein levels in the jejunum. Also, the bacteriophage administration resulted in a decrease in serum TNF-α and IL-1β levels, a down-regulation of TNF-α and IL-6 mRNA levels in the jejunum, and the inhibition of jejunal TLR-4/NF-κB pathway activation induced by ETEC infection. Moreover, the bacteriophage administration increased the levels of acetic acid, propionic acid, butyric acid, and total short-chain fatty acids in the caecum content. The bacteriophage administration increased the Shannon index, increased the abundance of Bacteroidota and Muribaculaceae, and decreased the abundance of Verrucomicrobiota and Akkermansiaceae in the colon contents of the ETEC-infected mice. Spearman’s correlation analysis indicates that the protective effects of bacteriophage on ETEC-induced intestinal impairment, inflammation, and intestinal barrier function are associated with regulating the abundance of Bacteroidota and Muribaculaceae in the colon contents of mice. Collectively, bacteriophage administration alleviates ETEC-induced diarrhea and intestinal impairment through regulating intestinal inflammation and gut microbiota in newly weaned mice.

Ionizing Radiation Dose Differentially Affects the Host-Microbe Relationship over Time.

Microorganisms that colonize in or on a host play significant roles in regulating the host's immunological fitness and bioenergy production, thus controlling the host's stress responses. Radiation elicits a pro-inflammatory and bioenergy-expensive state, which could influence the gut microbial compositions and, therefore, the host-microbe bidirectional relationship. To test this hypothesis, young adult mice were exposed to total body irradiation (TBI) at doses of 9.5 Gy and 11 Gy, respectively. The irradiated mice were euthanized on days 1, 3, and 9 post TBI, and their descending colon contents (DCCs) were collected. The 16S ribosomal RNAs from the DCCs were screened to find the differentially enriched bacterial taxa due to TBI. Subsequently, these data were analyzed to identify the metagenome-specific biofunctions. The bacterial community of the DCCs showed increased levels of diversity as time progressed following TBI. The abundance profile was the most divergent at day 9 post 11 Gy TBI. For instance, an anti-inflammatory and energy-harvesting bacterium, namely, Firmicutes, became highly abundant and co-expressed in the DCC with pro-inflammatory Deferribacteres at day 9 post 11 Gy TBI. A systems evaluation found a diverging trend in the regulation profiles of the functional networks that were linked to the bacteria and metabolites of the DCCs, respectively. Additionally, the network clusters associated with lipid metabolism and bioenergy synthesis were found to be activated in the DCC bacteria but inhibited in the metabolite space at day 9 post 11 Gy. Taking these results together, the present analysis indicated a disrupted mouse-bacteria symbiotic relationship as time progressed after lethal irradiation. This information can help develop precise interventions to ameliorate the symptoms triggered by TBI.

A step‐by‐step progressive strategy exploring whole metabolic profiles in vivo for Polygalae Radix with/without licorice

AbstractIntroductionPolygalae Radix (PR) is known to relieve toxicity and increase efficiency in various diseases after processing. However, there were few studies for aromatic carboxylic acids (ACAs) due to the limited detection, especially for the metabolites within m/z 100–2000.ObjectivesThis study aims to elucidate the whole metabolism of PR with/without licorice (LP), focusing on metabolites within m/z 100–2000 and pharmacodynamics in vivo.Material and methodsThis study was established by the combination of multidimensional ultra‐high performance liquid chromatography coupled with a mass spectrometer (UPLC–MS) technology with protein sedimentation method to analyze metabolites in plasma, brain, colon, and stomach contents. Quantitative monitoring ACAs was enhanced with our novel stable isotope derivatization (SILD) technique. And then the pharmacokinetics (PK) study of relatively large metabolites was carried out. A targeted network pharmacology approach was established to avoid false positive results, mapping interactions relevant to Alzheimer's disease (AD), and other conditions.ResultsThe 85 polygala metabolites were qualitatively analyzed in plasma, brain, colon, and stomach contents. The 11 types of relatively large metabolites and 8 types of ACAs were quantitatively monitored. Among them, nine types of relatively large metabolites were assessed through PK studies. In targeted network pharmacology, it highlighted the significance of small molecular metabolites, including ACAs et al, which were frequently overlooked. LP may play a more key role mainly through neural active ligand‐receptor interaction, AD, and pertussis pathways. These findings have outlined a step‐by‐step strategy for in‐depth research in vivo, laying a foundation for further verification of biological function.

Immunomodulatory Mechanisms of Tea Leaf Polysaccharide in Mice with Cyclophosphamide-Induced Immunosuppression Based on Gut Flora and Metabolomics.

Tea polysaccharides (TPSs) are receiving increasing attention because of their diverse pharmacological and biological activities. Here, we explored the immunoregulatory mechanisms of TPSs from fresh tea leaves in a mouse model of cyclophosphamide (CTX)-induced immunosuppression in terms of gut microbiota and metabolites. We observed that TPSs significantly increased the body weight and alleviated CTX-induced thymus atrophy in the immunosuppressed mice; they also increased the plasma levels of immunoglobulins A and M, interleukin (IL) 1β, IL-6, inducible nitric oxide synthase, and tumor necrosis factor α. Furthermore, we conducted 16S rDNA sequencing of cecal contents, resulting in the acquisition of 5008 high-quality bacterial 16S rDNA gene reads from the sequencing of mouse fecal samples. By analyzing the data, we found that TPSs regulated the gut microbiota structure and diversity and alleviated the CTX-induced dysregulation of gut microbiota. The colonic contents of mice were subjected to analysis using the UPLC-Q-TOF/MS/MS technique for the purpose of untargeted metabolomics. In the course of our metabolite identification analysis, we identified a total of 2685 metabolites in positive ion mode and 1655 metabolites in negative ion mode. The analysis of these metabolites indicated that TPSs improved CTX-induced metabolic disorders by regulating the levels of metabolites related to tryptophan, arginine, and proline metabolism. In conclusion, TPSs can alleviate CTX-induced immunosuppression by regulating the structural composition of gut microbiota, indicating the applicability of TPSs as novel innate immune modulators in health foods or medicines.

Microbiota-derived tryptophan metabolism and AMPK/mTOR pathway mediate antidepressant-like effect of Shugan Hewei Decoction.

Depression is a common psychological disorder, accompanied by a disturbance of the gut microbiota and its metabolites. Recently, microbiota-derived tryptophan metabolism and AMPK/mTOR pathway were found to be strongly linked to the development of depression. Shugan Hewei Decoction (SHD) is a classical anti-depression traditional Chinese medicine formula. Although, we have shown that SHD exerted antidepressant effects via cecal microbiota and cecum NLRP3 inflammasome, the specific mechanism of SHD on metabolism driven by gut microbiota is unknown. In this study, we focus on the tryptophan metabolism and AMPK/mTOR pathway to elucidate the multifaceted mechanisms of SHD. Male rats were established to the chronic unpredictable stress (CUS)/social isolation for 6weeks, and SHD-L (7.34g/kg/d), SHD-H (14.68g/kg/d), Fructooligosaccharide (FOS) (3.15g/kg/d) were given by intragastric administration once daily during the last 2weeks. Behavioral experiments were carried out to evaluate the model. The colonic content was taken out for shotgun metagenomic sequencing combined with the untargeted metabolomics, the targeted tryptophan metabolomics. ELISA was used to detect the levels of zonula occludens 1 (ZO-1), Occludin in colon, as well as lipopolysaccharide (LPS), diamine oxidase (DAO), D-lactate (DLA) in serum. The expressions of mRNA and proteins of adenosine monophosphate-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR) pathway of autophagy were examined using RT-qPCR and Western blot in colon. SHD modulated gut microbiota function and biological pathways, which were related to tryptophan metabolism. In addition, SHD could regulate microbiota-derived tryptophan production (such as reduction of 3-HK, 3-HAA etc., increment of ILA, IAA etc.), which metabolites belong to kynurenine (KYN) and indole derivatives. Further, SHD reduced intestinal permeability and enhanced the intestinal barrier function. Moreover, SHD could upregulate the levels of AMPK, microtubule associated protein light chain 3 (LC3), autophagy related protein 5 (ATG5) and Beclin1, downregulate the levels of mTOR, p62, promoted autophagy in colon. Spearman's analysis illustrated the close correlation between tryptophan metabolites and intestinal barrier, AMPK/mTOR pathway. SHD may exert antidepressant-like effects by regulating microbiota-derived tryptophan metabolism, and triggering the AMPK/mTOR pathway of autophagy, enhancing the intestinal barrier function.

Interplay between fluorine and cadmium on intestinal accumulation, oxidative stress, permeability and inflammatory response in rats

Fluorine (F) and Cadmium (Cd) have given rise to public concern regarding their adverse impacts on the environment and human beings. Yet, the toxic interplay between F and Cd on the intestine is still vague. Aiming to investigate the role of F on Cd-damaged intestine, a total of five groups of 30 SD rats were picked at random to be gavaged for 90 days: Control group (Ultra-pure water), Cd (Cd 1 mg/kg), Cd+LF (Cd 1 mg/kg+F 15 mg/kg), Cd+MF (Cd 1 mg/kg+F 45 mg/kg), and Cd+HF (Cd 1 mg/kg+F 75 mg/kg). It demonstrated that Cd enriched in the intestine and disordered intestinal barrier of rats. Interestingly, two side effects of F were observed resisting to the Cd toxicity. The Cd levels in colon contents were attenuated by 45.45 %, 28.11 %, and 19.54 % by F supplement, respectively. In the Cd+LF group, SOD, GSH-Px, and CAT activities elevated by 0.93, 1.76, and 1.78 times, respectively, and the MDA content reduced 0.67 times; the expressions of NQO1, SOD2, and GSH-Px mRNA markedly enhanced, as well as the Keap1 mRNA significantly decreased. Nevertheless, all indexes above in the Cd+HF group showed the opposite trends. Furthermore, LPS levels decreased by 45.93 % for the Cd+LF group and increased by 12.70 % in that the Cd+HF group. The ZO-1 expression in the Cd+LF group increased, whereas the Cd+HF group's expressions of Claudin-1, Occludin, and ZO-1 were all diminished by 35.46 %, 27.23 %, and 16.32 %, respectively. Moreover, the levels of TNF-α, IL-1β and TLR-4 decreased and IL-10 level promoted, while all showed opposite trends in the Cd+HF group. Collectively, it indicated there is a twofold interplay between F and Cd on intestinal damage and mainly depends on F dosages.

Melatonin mitigates chemotherapy-induced small intestinal atrophy in rats and reduces cytotoxicity in murine intestinal organoids.

Cancer continues to pose a significant global health challenge, with gastrointestinal (GI) cancers among the most prevalent and deadly forms. These cancers often lead to high mortality rates and demand the use of potent cytotoxic chemotherapeutics. For example, 5-fluorouracil (5-FU) forms the backbone of chemotherapy regimens for various GI cancers, including colorectal cancer. While these chemotherapeutics efficiently kill cancer cells, they frequently cause off-target effects such as chemotherapy-induced mucositis (CIM), characterized by debilitating symptoms like pain, nausea, and diarrhoea, necessitating medical intervention. In this study, we elucidated the potential of melatonin and misoprostol to reduce 5-FU-induced small intestinal mucositis. Morphological and cellular changes in the jejunum, along with colonic faecal water content were quantified in rats as markers for CIM. Additionally, the effects of melatonin were investigated in vitro on 5-FU treated murine intestinal organoids. The results showed that melatonin prevented villus atrophy in the rat jejunal mucosa and upheld cell viability in murine intestinal organoids. In contrast, misoprostol alone or in combination with melatonin did not significantly affect CIM caused by 5-FU. These in vivo and in vitro experiments provided promising insights that melatonin may be used as a preventive and/or adjuvant combination therapy to prevent and reduce CIM, holding the potential to enhance cancer treatment outcomes and improve patient quality-of-life.

Moxibustion with seed-size moxa cones alleviates colonic injury in mice with ulcerative colitis by regulating TLR4/MyD88/NF-κB signaling pathway.

To observe the effect of moxibustion with seed-size moxa cones on the Toll-like receptor 4(TLR4)/myeloid differentiation factor 88(MyD88)/nuclear transcription factor-κB(NF-κB) signaling pathway in mice with ulcerative colitis(UC), so as to explore the therapeutic mechanism of moxibustion with seed-size moxa cones on colonic injury in UC. Forty male C57BL/6 mice were randomly divided into blank group, model group, moxibustion group, and western medicine group, with 10 mice in each group. The UC mouse model was established by 3% DSS solution by free drinking for 7 consecutive days. Mice in the moxibustion group were treated with seed-size moxa cones at "Zhongwan"(CV12), "Tianshu"(ST25) and "Shangjuxu"(ST37), 3 moxa cones per point, with each cone applied for approximately 30 s, while mice in the western medicine group were orally administered with 300 mg/kg mesalazine solution, which were both conducted once a day for 7 consecutive days. The general condition of mice was observed every 2 days, and the disease activity index (DAI) score was calculated. HE staining was used to observe the morphology of colonic tissue in mice. ELISA was used to detect the serum interleukin(IL)-1β, tumor necrosis factor(TNF)-α, IL-6, and IL-8 contents. Immunohistochemistry was used to detect the positive expression of TLR4 and MyD88 in colonic tissue of mice. Real-time fluorescence quantitative PCR was used to detect the expression levels of TLR4, MyD88, and NF-κB p65 mRNAs in colonic tissue. Compared with the blank group, varying degrees of soft or watery stools were observed, colon length and body weight were decreased(P<0.01) in mice of the model group, while DAI score, colon weight index, mucosal damage score, colonic pathological score, serum IL-1β, TNF-α, IL-6, and IL-8 contents, positive expressions of TLR4 and MyD88, and TLR4, MyD88, and NF-κB p65 mRNA expressions in colonic tissue were increased(P<0.01). Compared with the model group, improved fecal characteristics were observed, colon length and body weight were increased(P<0.01) in mice of the moxibustion group and western medicine group, while DAI scores, colon weight indexes, mucosal damage scores, colonic pathological score, serum contents of IL-1β, TNF-α, IL-6, and IL-8, positive expressions of TLR4 and MyD88, and TLR4, MyD88, and NF-κB p65 mRNA expressions in colonic tissue were decreased(P<0.01, P<0.05). There was no significant difference in the above indicators between the moxibustion group and the western medicine group. Moxibustion with seed-size moxa cones may alleviate colonic injury in UC mice by regulating the TLR4/MyD88/NF-κB signaling pathway and reducing the release of inflammatory factors.

The effect of Lonicerae flos and Rhizoma curcumae longae extract on the intestinal development and function of broilers

This study was conducted to explore effects of Lonicerae flos and Rhomoma curcumae longae extracts (LR) on intestinal function of broilers. Three hundred broiler chickens were randomly assigned to the following five groups. The control group were fed the basal diet; the antibiotic group were fed the basal diet supplemented with spectinomycin hydrochloride (50 million units/ton) + lincomycin hydrochloride (25 g/ton); the LRH, LRM and LRL groups were fed the basal diet supplemented with a high dose (750 g/ton of feed), normal dose (500 g/ton of feed), or low dose (250 g/ton of feed) of LR, respectively. The changes of intestinal structure, intestinal digestive enzyme activities, antioxidant enzyme activities, inflammatory cytokines, and bacterial abundances in the colon and cecum contents were determined. The results indicated that compared with the control group and the antibiotic group, LR significantly increased the villus length/crypt depth (VCR) of the intestine, and significantly inhibited oxidative stress and inflammatory responses in the broiler intestine. In addition, LR regulated intestinal function by increasing the abundance of the intestinal microorganisms in broilers. In conclusion, LR improved antioxidant capacity, intestinal morphology, and microorganisms, and inhibited inflammatory response. The effect of high and medium doses of LR was better than lower doses.

Age-related decline in goblet cell numbers and mucin content of the human colon: Implications for lower bowel functions in the elderly

Background & aimsOlder people experience a greater incidence of lower bowel disorders, including constipation. Causes can include factors associated with growing older, such as use of medications or disease, but compounded by degenerative changes within the bowel wall. It has been suggested that the latter is exacerbated by loss of an effective mucosal barrier to luminal contents. In human colon, little is known about the impact of ageing on key components of this barrier, namely the goblet cells and mucin content. MethodsChanges in the number of goblet cells and density of mucin content were investigated in macroscopically normal human ascending (AC; n = 13) and descending (DC; n = 14) colon from elderly (≥ 67 years) and younger adults (60 years and below). Samples were serially sectioned and stained for haematoxylin and eosin to assess tissue morphology, and alcian blue periodic acid Schiff (ABPAS) and MUC-2 antibody to identify goblet cells producing mucins. New procedures in visualization and identification of goblet cells and mucin contents were employed to ensure unbiased counting and densitometric analysis. ResultsCompared with the younger adults, the numbers of goblet cells per crypt were significantly lower in the elderly AC (72 ± 1.2 vs 51 ± 0.5) and DC (75 ± 2.6 vs. 54 ± 1.9), although this reduction did not reach statistical significance when assessed per mucosal area (AC: P = 0.068; DC: P = 0.096). In both regions from the elderly, numerous empty vesicles (normally containing mucins) were observed, and some areas of epithelium were devoid of goblet cells. Thus, the density of mucin content per unit mucosal area were significantly reduced with age. ConclusionsAgeing could result in a reduced number of goblet cells and development of degenerative changes in mucin production. Together, these have implications for the mucus barrier function in the colon of elderly individuals.

Intestinal microbiota in children with chronic viral hepatitis

The article is devoted to a review of the literature on the study of intestinal microbiota in chronic viral hepatitis in children. The results of recent studies of microbial diversity of colon contents using 16S ribosomal RNA sequencing are presented. Scientific research in recent years has proven the influence of changes in the microbiota and its individual representatives on the formation of complications in patients with chronic viral hepatitis, the development of fibrosis/cirrhosis. Changed quantitative and species ratios of microorganisms can lead to the launch of pathological reactions in the intestinal-liver axis system. A significant reduction in the number of bacteria such as Clostridia and Bacteroidia (Faecalibacterium, Roseburia inilinivorans, Roseburia intestinalis, Coprococcus comes) causes low production of short-chain fatty acid butyrate, which can interfere with the functioning of tight junction proteins. Leaks and increased intestinal permeability create conditions for the formation of inflammation due to the activity of pro-inflammatory cytokines. Violation of the intestinal barrier function creates the opportunity for the penetration of bacteria, lipopolysaccharide complexes, bacterial ligands and metabolites, leading to the development of immunopathological reactions. These changes in the pediatric population are less noticeable than in the adult cohort of patients, since the clinical course of chronic viral hepatitis in children has a smoother course. However, periods of exacerbation, which are characterized by clinical and laboratory changes, may maintain the risk of developing fibrogenesis activity in older age groups. Data on intestinal microbial diversity in adult patients with chronic viral hepatitis B and C are presented separately. The possibilities of using pre- and probiotic therapy in the complex treatment of chronic liver diseases in adults and children are considered.

Tongbian formula alleviates slow transit constipation by increasing intestinal butyric acid to activate the 5-HT signaling

Slow transit constipation (STC) is a long-lasting and prevalent intestinal condition, marked by hard, dry feces. The primary cause of STC may be attributed to an imbalance in the gut’s microbial community and alterations in its metabolic byproducts. Tongbian formula (TB), a traditional Chinese medicinal formula, has been used to treat STC and shows a great effect on relieving constipation. The role of TB in regulating intestinal microbiota has not been fully elucidated. Herein, we investigated the potential effect of TB on gut microbiota and further explored the potential mechanism behind its effects. Our study demonstrated that TB significantly increased fecal water content and intestinal ink propulsion rate in loperamide (Lope)-induced STC rats. 5-HT signaling was suppressed in STC colon tissue, and the abundance of butyric acid (BA) in colonic contents was significantly down-regulated after Lope treatment. Notably, TB administration led to the restoration of microbial dysbiosis and the up-regulation of BA content, subsequently activating 5-HT signaling pathways. When BA was combined with a tryptophan hydroxylase-1 (TPH1) inhibitor, which is crucial for 5-HT synthesis, its therapeutic efficacy for treating STC was compromised. TB alleviates STC by reversing the intestinal microbiota imbalance and activating the 5-HT signaling in the colon through increasing BA levels. These findings suggest that TB is an ideal candidate for STC treatment.

Apple polyphenols prevent patulin-induced intestinal damage by modulating the gut microbiota and metabolism of the gut-liver axis

Patulin (PAT), a foodborne toxin, causes severe intestinal damage. To mitigate this health threat, mice were pretreated with apple polyphenols (AP) in their drinking water (0.01 % and 0.05 %) for eight weeks, followed by exposure to PAT during the last two weeks. Subsequently, histopathological and biochemical evaluations of intestinal tissues were conducted, alongside assessments of alterations in gut microbiota, colonic content metabolome, and hepatic metabolome. Consequently, AP alleviated PAT-induced villus and crypt injury, mucus depletion, GSH level decline, GSH-Px and SOD activity reduction, and MPO activity elevation. Notably, AP counteracted PAT-mediated microbiota disruptions and promoted the abundance of beneficial bacteria (Dubosiella, Akkermansia, Lachnospiraceae, and Lactobacillus). Furthermore, AP counteracted PAT-induced metabolic disorders in the colonic contents and liver. Ultimately, AP prevented intestinal injury by regulating the gut microbiota and amino acid, purine, butanoate, and glycerophospholipid metabolism in the gut-liver axis. These results underscore the potential of AP to prevent foodborne toxin-induced intestinal damage.

Modulation of anxiety-like behavior in galactooligosaccharide-fed mice: A potential role for bacterial tryptophan metabolites and reduced microglial reactivity

Prebiotic galactooligosaccharides (GOS) reduce anxiety-like behaviors in mice and humans. However, the biological pathways behind these behavioral changes are not well understood. To begin to study these pathways, we utilized C57BL/6 mice that were fed a standard diet with or without GOS supplementation for 3 weeks prior to testing on the open field. After behavioral testing, colonic contents and serum were collected for bacteriome (16S rRNA gene sequencing, colonic contents only) and metabolome (UPLC-MS, colonic contents and serum data) analyses. As expected, GOS significantly reduced anxiety-like behavior (i.e., increased time in the center) and decreased cytokine gene expression (Tnfa and Ccl2) in the prefrontal cortex. Notably, time in the center of the open field was significantly correlated with serum methyl-indole-3-acetic acid (methyl-IAA). This metabolite is a methylated form of indole-3-acetic acid (IAA) that is derived from bacterial metabolism of tryptophan. Sequencing analyses showed that GOS significantly increased Lachnospiraceae UCG006 and Akkermansia; these taxa are known to metabolize both GOS and tryptophan. To determine the extent to which methyl-IAA can affect anxiety-like behavior, mice were intraperitoneally injected with methyl-IAA. Mice given methyl-IAA had a reduction in anxiety-like behavior in the open field, along with lower Tnfa in the prefrontal cortex. Methyl-IAA was also found to reduce TNF-α (as well as CCL2) production by LPS-stimulated BV2 microglia. Together, these data support a novel pathway through which GOS reduces anxiety-like behaviors in mice and suggests that the bacterial metabolite methyl-IAA reduces microglial cytokine and chemokine production, which in turn reduces anxiety-like behavior.

The Severity of DSS-Induced Colitis Is Independent of the SCFA-FFAR2/3-GLP-1 Pathway Despite SCFAs Inducing GLP-1 Secretion via FFAR2/3.

Short-chain fatty acids (SCFAs) are the major microbial metabolites produced from the fermentation of dietary fiber in the gut. They are recognised as secretagogues of the glucagon-like peptides, GLP-1 and GLP-2, likely mediated by the activation of free fatty acid receptors 2 and 3 (FFAR2 and 3) expressed on enteroendocrine L-cells. Fiber-deficient diets are associated with decreased intestinal function and decreased colonic GLP-1 and GLP-2 content. Here, we speculated that the lowered colonic GLP-1 observed following a fiber-free diet was a consequence of decreased SCFA production and a subsequent decrease in FFAR2/3 activation. Furthermore, we explored the consequences of a fiber-free diet followed by intestinal injury, and we mechanistically explored the SCFA-FFAR2/3-GLP-1 pathway to explain the increased severity. Colonic luminal content from mice fed either a fiber-free or chow diet were analysed for SCFA content by LC-MS. FFAR2/3 receptor contributions to SCFA-mediated colonic GLP-1 secretion were assessed in isolated perfused preparations of the colon from FFAR2/3 double knockout (KO) and wild-type (WT) mice. Colitis was induced by the delivery of 3% dextran sulfate sodium (DSS) for 4 days in the drinking water of mice exposed to a fiber-free diet for 21 days. Colitis was induced by the delivery of 3% DSS for 7 days in FFAR2/3 KO mice. The removal of dietary fiber significantly decreased SCFA concentrations in the luminal contents of fiber-free fed mice compared to chow-fed mice. In the perfused colon, luminal SCFAs significantly increased colonic GLP-1 secretion in WT mice but not in FFAR2/3 KO mice. In the DSS-induced colitis model, the removal of dietary fiber increased the severity and prevented the recovery from intestinal injury. Additionally, colitis severity was similar in FFAR2/3 KO and WT mice after DSS application. In conclusion, the results confirm that the removal of dietary fiber is sufficient to decrease the colonic concentrations of SCFAs. Additionally, we show that a fiber-free diet predisposes the colon to increased intestinal injury, but this effect is independent of FFAR2 and FFAR3 signalling; therefore, it is unlikely that a fiber-free diet induces a decrease in luminal SCFAs and sensitivity to intestinal disease involves the SCFA-FFAR2/3-GLP-1 pathway.

Intracellular Polysaccharides of Eurotium cristatum Exhibited Anticolitis Effects in Association with Gut Tryptophan Metabolism.

This study is to investigate the protective effects of Eurotium cristatum intracellular polysaccharides (ECIP) on dextran sodium sulfate (DSS)-induced ulcerative colitis (UC). The oral administration of ECIP could downregulate the disease activity index (DAI) and ameliorate the colonic shortening, immune stress, and damage caused by DSS. In addition, ECIP treatment increased the colonic contents of SCFAs including acetic, propionic, and butyric acids in UC mice. Targeted and untargeted metabolic analysis suggested that ECIP dramatically altered the tryptophan metabolism in the feces of UC mice and promoted the conversion of tryptophan into indole metabolites including indolepyruvate and indole-3-acetic acid (IAA) and indolealdehyde (IAId). Moreover, ECIP observably increased the content of colonic IL-22 and stimulated the relative concentration and relative expression of tight junction molecules in mRNA and proteins levels. Conclusively, consumption of ECIP can improve colon damage and its related effects of UC by promoting the production of IAA and IAId to reinforce intestinal barriers.