Mucosal Ecological Network of Epithelium and Immune Cells for Gut Homeostasis and Tissue Healing

Intestinal epithelial cell metabolism at the interface of microbial dysbiosis and tissue injury

The intestinal epithelium represents the most regenerative tissue in the human body, located in proximity to the dense and functionally diverse microbial milieu of the microbiome. Episodes of tissue injury and incomplete healing of the intestinal epithelium are a prerequisite for immune reactivation and account for recurrent, chronically progressing phenotypes of inflammatory bowel diseases (IBD). Mitochondrial dysfunction and associated changes in intestinal epithelial functions are emerging concepts in the pathogenesis of IBD, suggesting impaired metabolic flexibility of epithelial cells affects the regenerative capacity of the intestinal tissue. Next to rendering the intestinal mucosa susceptible to inflammatory triggers, metabolic reprogramming of the epithelium is implicated in shaping adverse microbial environments. In this review, we introduce the concept of "metabolic injury" as a cell autonomous mechanism of tissue wounding in response to mitochondrial perturbation. Furthermore, we highlight epithelial metabolism as intersection of microbiome, immune cells and epithelial regeneration.

Intestinal Barrier and Permeability in Health, Obesity and NAFLD

The largest surface of the human body exposed to the external environment is the gut. At this level, the intestinal barrier includes luminal microbes, the mucin layer, gastrointestinal motility and secretion, enterocytes, immune cells, gut vascular barrier, and liver barrier. A healthy intestinal barrier is characterized by the selective permeability of nutrients, metabolites, water, and bacterial products, and processes are governed by cellular, neural, immune, and hormonal factors. Disrupted gut permeability (leaky gut syndrome) can represent a predisposing or aggravating condition in obesity and the metabolically associated liver steatosis (nonalcoholic fatty liver disease, NAFLD). In what follows, we describe the morphological-functional features of the intestinal barrier, the role of major modifiers of the intestinal barrier, and discuss the recent evidence pointing to the key role of intestinal permeability in obesity/NAFLD.

The Probiotic Properties of Lactic Acid Bacteria and Their Applications in Animal Husbandry

The intestinal tract of animals is a complex ecosystem in which nutrients, microbiota and host cells interact extensively. Probiotics can be considered as part of the natural microbiota of the gut and are involved in improving homeostasis. Lactic acid bacteria (LAB) is a general term for a class of non-spore forming, gram-positive bacteria whose main product of fermented sugar is lactic acid. LAB are considered to be a type of probiotic due to their health-promoting effects on the host, and are very effective in the treatment of human and animal diseases. LAB have been widely used as a class of microbial agents in the field of livestock and poultry breeding. They are also considered to be the best substitutes for antibiotics to improve animal health. Here, we review the biological functions, probiotic characteristics and applications of LAB in livestock and poultry breeding. This review is designed to provide a theoretical base for the in-depth exploration and promotion of LAB use in animal diets.

The Correlation Between MYO9B Gene Polymorphism and Inflammatory Bowel Disease in the Guangxi Zhuang Population

Objective

To analyze the correlation between site rs962917 of the MYO9B gene and inflammatory bowel disease (IBD) in the Guangxi Zhuang nationality population.

Methods

The intestinal mucosa tissue of 153 IBD subjects (Han and Zhuang patients only) in the Guangxi Zhuang autonomous region comprised the case group, and the intestinal mucosa tissue of 155 healthy subjects (Han and Zhuang patients only) in the same region represented the control group. Deoxyribonucleic acid was extracted from the intestinal mucosa tissue of each experimental group, and the MYO9B gene-target fragment containing the single nucleotide polymorphism (SNP) site rs962917 was designed. Finally, polymerase chain reaction products were obtained by amplification, analyzed, and compared using the sequencing results.

Results

The results indicated that the genotype frequency of the MYO9B SNP site rs962917 between Crohn’s disease (CD) and control groups of Zhuang and Han participants differed significantly (P < 0.05). Furthermore, the genotype frequency of MYO9B site rs962917 differed significantly between the Zhuang and Han population groups (P < 0.05).

Conclusion

Site rs962917 of the MYO9B gene is related to CD susceptibility and incidence among the Guangxi Zhuang population.

Signature changes in gut microbiome are associated with increased susceptibility to HIV-1 infection in MSM

BACKGROUND

Men who have sex with men (MSM) have been disproportionately affected by HIV-1 since the beginning of the AIDS pandemic, particularly in the USA and Europe. Compared to men who have sex with women (MSW), MSM have a distinct fecal microbiome regardless of HIV-1 infection. However, it is unclear whether the MSM-associated gut microbiome affects the susceptibility and progression of HIV-1 infection. We studied fecal microbiome profiles, short-chain fatty acids, and blood plasma inflammatory cytokines of 109 HIV-1 seroconverters (SC) from the early, 1984-1985 phase of the HIV-1 pandemic in the Multicenter AIDS Cohort Study (MACS) before and after HIV-1 infection compared to 156 HIV-1-negative MACS MSM (negative controls [NC]).

RESULTS

We found that family Succinivibrionaceae, S24-7, Mogibacteriaceae, Coriobacteriaceae, and Erysipelotrichaceae were significantly higher (p<0.05), whereas Odoribacteraceae, Verucomicrobiaceae, Bacteroidaceae, Barnesiellaceae, and Rikenellaceae were significantly lower (p<0.05), in SC before HIV-1 infection compared to NC. At the species level, Prevotella stercorea, Eubacterium biforme, and Collinsella aerofaciens were significantly higher (p<0.05), and Eubacterium dolichum, Desulfovibrio D168, Alistipes onderdonkii, Ruminococcus torques, Bacteroides fragilis, Bacteroides caccae, Alistipes putredinis, Akkermansia muciniphila, Bacteroides uniformis, and Bacteroides ovatus were significantly lower (p<0.05) in SC before HIV-1 infection compared to NC. After HIV-1 infection, family Prevotellaceae and Victivallaceae and species Bacteroides fragilis and Eubacterium cylindroides were significantly higher (p<0.05) in SC who developed AIDS within 5 years compared to the SC who were AIDS free for more than 10 years without antiretroviral therapy (ART). In addition, family Victivallaceae and species Prevotella stercorea, Coprococcus eutactus, and Butyrivibrio crossotus were significantly higher (p<0.05) and Gemmiger formicilis and Blautia obeum were significantly lower (p<0.05) after HIV-1 infection in SC who developed AIDS within 5-10 years compared to the SC who were AIDS-free for more than 10 years without ART. Furthermore, plasma inflammatory cytokine levels of sCD14, sCD163, interleukin 6, and lipopolysaccharide binding protein were significantly higher in SC with p<0.05 before HIV-1 infection compared to NC.

CONCLUSIONS

Our results suggest that pathogenic changes in the gut microbiome were present in MSM several months prior to infection with HIV-1 in the early phase of the AIDS pandemic in the USA. This was associated with increased inflammatory biomarkers in the blood and risk for development of AIDS. Video abstract.

Mucosal vaccines: wisdom from now and then

The oral and nasal cavities are covered by the mucosal epithelium that starts at the beginning of the aero-digestive tract. These mucosal surfaces are continuously exposed to environmental antigens including pathogens and allergens and are thus equipped with a mucosal immune system that mediates initial recognition of pathogenicity and initiates pathogen-specific immune responses. At the dawn of our scientific effort to explore the mucosal immune system, dental science was one of the major driving forces as it provided insights into the importance of mucosal immunity and its application for the control of oral infectious diseases. The development of mucosal vaccines for the prevention of dental caries was thus part of a novel approach that contributed to building the scientific foundations of the mucosal immune system. Since then, mucosal immunology and vaccines have gone on a scientific journey to become one of the major entities within the discipline of immunology. Here, we introduce our past and current efforts and future directions for the development of mucosal vaccines, specifically a rice-based oral vaccine (MucoRice) and a nanogel-based nasal vaccine, with the aim of preventing and controlling gastrointestinal and respiratory infectious diseases using the interdisciplinary fusion of mucosal immunology with agricultural science and biomaterial engineering, respectively.

High-Fructose Diet Alters Intestinal Microbial Profile and Correlates with Early Tumorigenesis in a Mouse Model of Barrett’s Esophagus

Esophageal adenocarcinoma (EAC) is mostly prevalent in industrialized countries and has been associated with obesity, commonly linked with a diet rich in fat and refined sugars containing high fructose concentrations. In meta-organisms, dietary components are digested and metabolized by the host and its gut microbiota. Fructose has been shown to induce proliferation and cell growth in pancreas and colon cancer cell lines and also alter the gut microbiota. In a previous study with the L2-IL-1B mouse model, we showed that a high-fat diet (HFD) accelerated EAC progression from its precursor lesion Barrett’s esophagus (BE) through changes in the gut microbiota. Aiming to investigate whether a high-fructose diet (HFrD) also alters the gut microbiota and favors EAC carcinogenesis, we assessed the effects of HFrD on the phenotype and intestinal microbial communities of L2-IL1B mice. Results showed a moderate acceleration in histologic disease progression, a mild effect on the systemic inflammatory response, metabolic changes in the host, and a shift in the composition, metabolism, and functionality of intestinal microbial communities. We conclude that HFrD alters the overall balance of the gut microbiota and induces an acceleration in EAC progression in a less pronounced manner than HFD.

Mucin-Type O-Glycans: Barrier, Microbiota, and Immune Anchors in Inflammatory Bowel Disease

Inflammatory bowel disease (IBD), which affects about 7 million people globally, is a chronic inflammatory condition of the gastrointestinal tract caused by gut microbiota alterations, immune dysregulation, and genetic and environmental factors. The association of microbial and immune molecules with mucin-type O-glycans has been increasingly noticed by researchers. Mucin is the main component of mucus, which forms a protective barrier between the microbiota and immune cells in the colon. Mucin-type O-glycans alter the diversity of gastrointestinal microorganisms, which in turn increases the level of O-glycosylation of host intestinal proteins via the utilization of glycans. Additionally, alterations in mucin-type O-glycans not only increase the activity and stability of immune cells but are also involved in the maintenance of intestinal mucosal immune tolerance. Although there is accumulating evidence indicating that mucin-type O-glycans play an important role in IBD, there is limited literature that integrates available data to present a complete picture of exactly how O-glycans affect IBD. This review emphasizes the roles of the mucin-type O-glycans in IBD. This seeks to provide a better understanding and encourages future studies on IBD glycosylation and the design of novel glycan-inspired therapies for IBD.

Intestinal CD11b+ B Cells Ameliorate Colitis by Secreting Immunoglobulin A

The intestinal mucosal immune environment requires multiple immune cells to maintain homeostasis. Although intestinal B cells are among the most important immune cells, little is known about the mechanism that they employ to regulate immune homeostasis. In this study, we found that CD11b⁺ B cells significantly accumulated in the gut lamina propria and Peyer's patches in dextran sulfate sodium-induced colitis mouse models and patients with ulcerative colitis. Adoptive transfer of CD11b⁺ B cells, but not CD11b^-/- B cells, effectively ameliorated colitis and exhibited therapeutic effects. Furthermore, CD11b⁺ B cells were found to produce higher levels of IgA than CD11b^- B cells. CD11b deficiency in B cells dampened IgA production, resulting in the loss of their ability to ameliorate colitis. Mechanistically, CD11b⁺ B cells expressed abundant TGF-β and TGF-β receptor II, as well as highly activate phosphorylated Smad2/3 signaling pathway, consequently promoting the class switch to IgA. Collectively, our findings demonstrate that CD11b⁺ B cells are essential intestinal suppressive immune cells and the primary source of intestinal IgA, which plays an indispensable role in maintaining intestinal homeostasis.

Toll-Like Receptors as Drug Targets in the Intestinal Epithelium

Toll-like receptors (TLRs) receptors are responsible for initiation of inflammatory responses by their recognition of molecular patterns present in invading microorganisms (such as bacteria, viruses or fungi) or in molecules released following tissue damage in disease states. Expressed in the intestinal epithelium, they initiate an intracellular signalling cascade in response to molecular patterns resulting in the activation of transcription factors and the release of cytokines, chemokines and vasoactive molecules. Intestinal epithelial cells are exposed to microorganisms on a daily basis and form part of the primary defence against pathogens by using TLRs. TLRs and their accessory molecules are subject to tight regulation in these cells so as to not overreact or react in unnecessary circumstances. TLRs have more recently been associated with chronic inflammatory diseases as a result of inappropriate regulation, this can be damaging and lead to chronic inflammatory diseases such as inflammatory bowel disease (IBD). Targeting Toll-like receptors offers a potential therapeutic approach for IBD. In this review, the current knowledge on the TLRs is reviewed along with their association with intestinal diseases. Finally, compounds that target TLRs in animal models of IBD, clinic trials and their future merit as targets are discussed.

Microbial-Driven Immunological Memory and Its Potential Role in Microbiome Editing for the Prevention of Colorectal Cancer

Over the last several years, many advances have been made in understanding the role of bacteria in the pathogenesis of gastrointestinal cancers. Beginning with Helicobacter pylori being recognized as the first bacterial carcinogen and the causative agent of most gastric cancers, more recent studies have examined the role of enteric microbes in colorectal cancer. In the digestive tract, these communities are numerous and have a complex interrelationship with local immune/inflammatory responses that impact the health of the host. As modifying the microbiome in the stomach has decreased the risk of gastric cancer, modifying the distal microbiome may decrease the risk of colorectal cancers. To date, very few studies have considered the notion that mucosal lymphocyte-dependent immune memory may confound attempts to change the microbial components in these communities. The goal of this review is to consider some of the factors impacting host-microbial interactions that affect colorectal cancer and raise questions about how immune memory responses to the local microbial consortium affect any attempt to modify the composition of the intestinal microbiome.

Polysaccharides From the Roots of Millettia Speciosa Champ Modulate Gut Health and Ameliorate Cyclophosphamide-Induced Intestinal Injury and Immunosuppression

Cyclophosphamide (CTX), a common anticancer drug, can cause a variety of side effects such as immunosuppression and intestinal mucosal injury. Polysaccharides are the major bioactive components of the roots of Millettia Speciosa Champ and have gained attention for their immunomodulatory activity. This study was designed to evaluate the immunomodulatory effect of Millettia Speciosa Champ polysaccharide (MSCP) on CTX-induced mice and the possible mechanism. The results showed that MSCP attenuated the CTX-induced decrease in body weight and immune organ indices in mice and promoted the secretion of immune-related cytokines (IL-2, IL-4, IL-10, TNF-α, and IgG). Meanwhile, MSCP restored intestinal morphology, increased the ratio of villus height/crypt depth (V/C), and improved the number of goblet cells and mucins expression. At the mRNA level, MSCP activated the TLRs/MyD88/NF-κB p65 pathway and enhanced the expression of genes related to intestinal mucosal integrity (Occludin1, Claudin1, and MUC-2). In addition, MSCP as a prebiotic improved microbial community diversity, regulated the relative abundance of dominant microbiota from the phylum level to the genus level, restored CTX-induced gut microbial dysbiosis, and promoted short-chain fatty acid production in mice. Based on the present findings, MSCP may modulate the immune response depending on enhancing intestinal health, suggesting that MSCP holds promise as a promising immunostimulant in functional foods and drugs.

Dietary Supplementation With Lactobacillus plantarum Ameliorates Compromise of Growth Performance by Modulating Short-Chain Fatty Acids and Intestinal Dysbiosis in Broilers Under Clostridium perfringens Challenge

Clostridium perfringens is an important zoonotic pathogen associated with food contamination and poisoning, gas gangrene, necrotizing enterocolitis or necrotic enteritis in humans and animals. Dysbacteriosis is supposedly associated with the development of C. perfringens infection induced necrotic enteritis, but the detailed relationship between intestinal health, microbiome, and C. perfringens infection-induced necrotic enteritis remains poorly understood. This research investigated the effect of probiotics on the growth performance and intestinal health of broilers, and the involved roles of intestinal microbiota and microbial metabolic functions under C. perfringens infection. Results showed that subclinical necrotic enteritis was successfully induced as evidenced by the significant lower body weight (BW), suppressed feed conversion ratio (FCR), decreased ileal villus height and mucosal barrier function, and increased ileal histopathological score and bursal weight index. Lactobacillus plantarum or Paenibacillus polymyxa significantly attenuated C. perfringens-induced compromise of growth performance (BW, FCR) and ileal mucosa damage as illustrated by the increased ileal villus height and villus/crypt ratio, the decreased ileal histopathological score and the enhanced ileal mucosal barrier function. L. plantarum also significantly alleviated C. perfringens-induced enlarged bursa of fabricius and the decreased levels of ileal total SCFAs, acetate, lactate, and butyrate. Furthermore, dietary L. plantarum improved C. perfringens infection-induced intestinal dysbiosis as evidenced by significantly enriched short-chain fatty acids-producing bacteria (Lachnospiraceae, Ruminococcaceae, Oscillospira, Faecalibacterium, Blautia), reduced drug-resistant bacteria (Bacteroides, Alistipes) and enteric pathogens (Escherichia coli, Bacteroides fragilis) and bacterial metabolic dysfunctions as illustrated by significantly increased bacterial fatty acid biosynthesis, decreased bacterial lipopolysaccharide biosynthesis, and antibiotic biosynthesis (streptomycin and vancomycin). Additionally, the BW and intestinal SCFAs were the principal factors affecting the bacterial communities and microbial metabolic functions. The above findings indicate that dietary with L. plantarum attenuates C. perfringens-induced compromise of growth performance and intestinal dysbiosis by increasing SCFAs and improving intestinal health in broilers.

Matrine protects against DSS-induced murine colitis by improving gut barrier integrity, inhibiting the PPAR-α signaling pathway, and modulating gut microbiota

Matrine is a naturally occurring quinolizidine alkaloid with various bioactivities. However, little is known of its function on ulcerative colitis (UC). Here, we investigated the effect and underlying mechanisms of matrine on dextran sulfate sodium (DSS)-induced UC mice. In this study, different concentrations of matrine were given to mice with DSS-induced colitis for a week. The symptoms of colitis, colonic pathology, inflammation-related indicators, and intestinal mucosal barrier function were detected and analyzed. Moreover, RNA-seq analysis in colon tissues was conducted, and 16S rDNA sequencing was carried out to evaluate the gut microbiota of colon contents. The results showed that matrine significantly alleviated clinical activity and histological changes of UC mice, inhibited the production of the pro-inflammatory cytokines, and improved gut barrier integrity. Moreover, RNA-seq analysis and experimental verification showed that matrine significantly inhibited the peroxisome proliferator-activated receptor-α (PPAR-α) signaling pathway. 16S rDNA sequencing revealed that matrine altered the composition and functions of gut microbiota, increased the abundance of Barnesiella intestinihominis and decreased the abundance of Helicobacter ganmani at the species level. In conclusion, matrine ameliorated DSS-induced colitis by improving gut barrier integrity, inhibiting the PPAR-α signaling pathway, and modulating gut microbiota. These suggested that matrine may be a therapeutic agent for UC treatment.

Irisin attenuates inflammation in a mouse model of ulcerative colitis by altering the intestinal microbiota

Evidence has demonstrated that the gut microbiota, which consists of probiotics and pathogenic microorganisms, is involved in the initiation of ulcerative colitis (UC) via the dysregulation of intestinal microflora and normal immune interactions, which ultimately leads to intestinal mucosal dysfunction. Irisin is released from muscle cells and displays anti-inflammatory effects; however, the mechanisms underlying irisin-mediated anti-inflammatory effects in UC have not been previously reported. In the present study, mice were divided into the following four groups: i) Control; ii) irisin; iii) dextran sulfate sodium (DSS) salt; and iv) DSS + irisin. Subsequently, the effects of irisin were investigated by observing alterations in intestinal microbes. Irisin significantly reduced the degree of inflammation in UC by reversing alterations to the macroscopic score, histological score, number of CD64⁺ cells and inflammatory cytokine alterations (P<0.05). Analysis of the microbial diversity in the stools of mice with active UC indicated that the five bacteria that displayed the greatest alterations in relative abundance were Alloprevotella, Bacteroides, Lachnospiraceae-UCG-001, Prebotellaceae-UCG-001 and Rikenellaceae-RCB-gut-group. Furthermore, Bactoroides were positively correlated with the histopathological score (P=0.001; R=0.977) and interleukin (IL)-23 levels (P=0.008; R=0.924). Alloprevotella (P=0.001; R=-0.943), Lachnospiraceae-UCG-001 (P=0.000; R=-0.973) and Rikenollaceae-RC8-gut-group (P=0.001; R=-0.971) were negatively correlated with the histopathological score. Furthermore, Lachnospiraceae-UCG-001 (P=0.01; R=-0.873) and Rikenollaceae-RC8-gut-group (P=0.049; R=-0.814) were negatively correlated with IL-23 levels. In summary, the results of the present study suggested that irisin improved inflammation in a UC mouse model potentially via altering the gut microbiota.

MALAT1 Maintains the Intestinal Mucosal Homeostasis in Crohn's Disease via the miR-146b-5p-CLDN11/NUMB Pathway

BACKGROUND AND AIMS

Intestinal homeostasis disorder is critical for developing Crohn's disease [CD]. Maintaining mucosal barrier integrity is essential for intestinal homeostasis, preventing intestinal injury and complications. Among the remarkably altered long non-coding RNAs [lncRNAs] in CD, we aimed to investigate whether metastasis-associated lung adenocarcinoma transcript 1 [MALAT1] modulated CD and consequent disruption of intestinal homeostasis.

METHODS

Microarray analyses on intestinal mucosa of CD patients and controls were performed to identify dysregulated lncRNAs. MALAT1 expression was investigated via qRT-PCR and its distribution in intestinal tissues was detected using BaseScope. Intestines from MALAT1 knockout mice with colitis were investigated using histological, molecular, and biochemical approaches. Effects of intestinal epithelial cells, transfected with MALAT1 lentiviruses and Smart Silencer, on monolayer permeability and apical junction complex [AJC] proteins were analysed. MiR-146b-5p was confirmed as a critical MALAT1 mediator in cells transfected with miR-146b-5p mimic/inhibitor and in colitis mice administered agomir-146b-5p/antagomir-146b-5p. Interaction between MALAT1 and miR-146b-5p was predicted via bioinformatics and validated using Dual-luciferase reporter assay and Ago2-RIP.

RESULTS

MALAT1 was aberrantly downregulated in the intestine mucosa of CD patients and mice with experimental colitis. MALAT1 knockout mice were hypersensitive to DSS-induced experimental colitis. MALAT1 regulated the intestinal mucosal barrier and regained intestinal homeostasis by sequestering miR-146b-5p and maintaining the expression of the AJC proteins NUMB and CLDN11.

CONCLUSIONS

Downregulation of MALAT1 contributed to the pathogenesis of CD by disrupting AJC. Thus, a specific MALAT1-miR-146b-5p-NUMB/CLDN11 pathway that plays a vital role in maintaining intestinal mucosal homeostasis may serve as a novel target for CD treatment.

Histological Hallmarks of Mucosal Healing in Inflammatory Bowel Diseases in the Era of Monoclonal Antibodies Therapy: New Insights and Perspectives

BACKGROUND

Chronic inflammatory bowel diseases (IBDs) are gaining increasing attention, both because they can severely reduce the quantity and quality of life, and because the advent of monoclonal antibodies has profoundly changed the natural history of these diseases. In recent years, the concept of mucosal healing has assumed a certain importance, and there are more and more clinical and pharmacological trials that consider this parameter among their endpoints, so much so that it may soon be included among the desirable clinical outcomes of patients with IBD.

METHODS

We performed a literature review of the Pubmed, Medline, and Web of Science (WoS) databases.

RESULTS

We selected 88 articles and then removed 6 duplicates; the final sample after accurate application of the inclusion criteria numbered 73 articles, with a level of evidence rating of three or four, according to Oxfords Evidence-based medicine. Our aim was to study the histological impact of monoclonal antibody therapies on mucosal healing, taking into consideration the few studies present in the literature. To perform this review, we compared studies that examined patients with Crohn's disease (CD) and/or ulcerative colitis (UC) undergoing monoclonal therapy versus patients undergoing other non-biological therapies (PICO statements).

CONCLUSIONS

We try to delineate how monoclonal antibodies have changed the natural history of IBD, acting at the microscopic level, and we believe that a careful analysis of the histopathology and the definition of the objective criteria for "Mucosa Healing" should enable this concept to be included among the clinical endpoints of patients affected by IBD, thus contributing to a better therapeutic management of these patients.

Intestinal microbiota participates in nonalcoholic fatty liver disease progression by affecting intestinal homeostasis

Nonalcoholic fatty liver disease (NAFLD) is a chronic liver disease with a pathogenesis that has not been fully elucidated. With the development of the theory of the gut-liver axis and the deepening of related research, the role of the intestinal tract in the pathogenesis of NAFLD has been investigated more. Intestinal microbiota, intestinal metabolites, and intestinal epithelial and immune-based barriers constitute the intestinal environment, which uses crosstalk to maintain the homeostasis of the intestinal environment. This paper reviews the progress in the study of intestinal microbiota, intestinal environment, and NAFLD and suggests that repair of intestinal functional balance may be a new idea for early prevention and intervention of NAFLD.

Innate lymphoid cells: The missing part of a puzzle in food allergy

Food allergy is an increasingly prevalent disease driven by uncontrolled type 2 immune response. Currently, knowledge about the underlying mechanisms that initiate and promote the immune response to dietary allergens is limited. Patients with food allergy are commonly sensitized through the skin in their early life, later on developing allergy symptoms within the gastrointestinal tract. Food allergy results from a dysregulated type 2 response to food allergens, characterized by enhanced levels of IgE, IL-4, IL-5, and IL-13 with infiltration of mast cells, eosinophils, and basophils. Recent studies raised a possible role for the involvement of innate lymphoid cells (ILCs) in driving food allergy. Unlike lymphocytes, ILCs lack They represent a group of lymphocytes that lack specific antigen receptors. ILCs contribute to immune responses not only by releasing cytokines and other mediators but also by responding to cytokines produced by activated cells in their local microenvironment. Due to their localization at barrier surfaces of the airways, gut, and skin, ILCs form a link between the innate and adaptive immunity. This review summarizes recent evidence on how skin and gastrointestinal mucosal immune system contribute to both homeostasis and the development of food allergy, as well as the involvement of ILCs toward inflammatory processes and regulatory mechanisms.

Application of biomaterials in periodontal tissue repair and reconstruction in the presence of inflammation under periodontitis through the foreign body response: Recent progress and perspectives

Periodontitis would cause dental tissue damage locally. Biomaterials substantially affect the surrounding immune microenvironment through treatment-oriented local inflammatory remodeling in dental periodontitis. This remodeling process is conducive to wound healing and periodontal tissue regeneration. Recent progress in understanding the foreign body response (FBR) and immune regulation, including cell heterogeneity, and cell-cell and cell-material interactions, has provided new insights into the design criteria for biomaterials applied in treatment of periodontitis. This review discusses recent progress and perspectives in the immune regulation effects of biomaterials to augment or reconstruct soft and hard tissue in an inflammatory microenvironment of periodontitis.

Differential analysis revealing APOC1 to be a diagnostic and prognostic marker for liver metastases of colorectal cancer

BACKGROUND

Colorectal cancer (CRC) is one of the most malignant gastrointestinal cancers worldwide. The liver is the most important metastatic target organ, and liver metastasis is the leading cause of death in patients with CRC. Owing to the lack of sensitive biomarkers and unclear molecular mechanism, the occurrence of liver metastases cannot be predicted and the clinical outcomes are bad for liver metastases. Therefore, it is very important to identify the diagnostic or prognostic markers for liver metastases of CRC.

AIM

To investigate the highly differentially expressed genes (HDEGs) and prognostic marker for liver metastases of CRC.

METHODS

Data from three NCBI Gene Expression Omnibus (GEO) datasets were used to show HDEGs between liver metastases of CRC and tumour or normal samples. These significantly HDEGs of the three GEO datasets take the interactions. And these genes were screened through an online tool to explore the prognostic value. Then, TIMER and R package were utilized to investigate the immunity functions of the HDEGs and gene set enrichment analysis was used to explore their potential functions.

RESULTS

Based on the selection criteria, three CRC datasets for exploration (GSE14297, GSE41258, and GSE49355) were chosen. Venn diagrams were used to show HDEGs common to the six groups and 47 HDEGs were obtained. The HDEGs were shown by using STRING and Cytoscape software. Based on the TCGA database, APOC1 showed significantly different expression between N2 and N0, and N2 and N1. And there was also a significant difference in expression between T2 and T4, and between T2 and T3. In 20 paired CRC and normal tissues, quantitative real-time polymerase chain reaction illustrated that the APOC1 mRNA was strongly upregulated in CRC tissues (P = 0.014). PrognoScan and GEPIA2 revealed the prognostic value of APOC1 for overall survival and disease-free survival in CRC (P < 0.05). TIMER showed that APOC1 has a close relationship with immune infiltration (P < 0.05).

CONCLUSION

APOC1 is a biomarker that is associated with both the diagnosis and prognosis of liver metastases of CRC.

Microbiome-Metabolomics Analysis Reveals the Protection Mechanism of α-Ketoacid on Adenine-Induced Chronic Kidney Disease in Rats

Objectives: As nitrogen-free precursors of corresponding essential amino, α-ketoacid have been widely prescribed to end-stage renal disease patients together with a low protein diet However, the impact of α-ketoacid on intestinal microbiota in chronic kidney disease (CKD) individuals is unknown. The study aims at investigating the variation in the intestinal microbiota and metabolic profile in response to α-ketoacid treatment in an adenine-induced CKD rat model. Design: Rats in the treatment groups were given solution of compound α-ketoacid tablets. At the end of the study, blood, feces, colon tissues and kidney tissues were collected and processed for biochemical analyses, histological and western blot analyses, 16S rRNA sequence and untargeted metabolomic analyses. Results: α-Ketoacid treatment reduced serum creatinine, blood urea nitrogen and 24 h urine protein, and alleviated tubular atrophy, glomerulosclerosis and interstitial fibrosis in adenine-induced CKD rats. Moreover, α-ketoacid significantly improved intestinal barrier and increased the abundance of Methanobrevibacter, Akkermansia, Blautia and Anaerositipes while reduced the abundance of Anaerovorax and Coprococcus_3 at the genus level. In addition, our results also demonstrated that α-ketoacid significantly reduced the concentrations of indoxyl sulfate, betaine, choline and cholesterol. Spearman's correlation analysis revealed that the abundance of Coprococcus_3 was positively correlated with serum level of betaine, trimethylamine N-oxide, indoxyl sulfate, cholic acid and deoxycholic acid. Conclusion: α-Ketoacid has a reno-protective effect against adenine-induced CKD, which may be mediated regulation of serum metabolic profiles via affecting intestinal microbial community.

Gut-Liver Axis in Nonalcoholic Fatty Liver Disease: the Impact of the Metagenome, End Products, and the Epithelial and Vascular Barriers

Nonalcoholic fatty liver disease (NAFLD) is a systemic, dynamic, heterogeneous, and multiaxis entity, the pathogenesis of which is still uncertain. The gut-liver axis is regulated and stabilized by a complex network encompassing a metabolic, immune, and neuroendocrine cross-talk between the gut, the microbiota, and the liver. Changes in the gut-liver axis affect the metabolism of lipids and carbohydrates in the hepatocytes, and they impact the balance of inflammatory mediators and cause metabolic deregulation, promoting NAFLD and its progression to nonalcoholic steatohepatitis. Moreover, the microbiota and its metabolites can play direct and indirect roles in gut barrier function and fibrosis development. In this review, we will highlight findings from the recent literature focusing on the gut-liver axis and its relation to NAFLD. Finally, we will discuss the impact of technical issues, design bias, and other limitations on current knowledge of the gut microbiota in the context of NAFLD.

Human antigen R (HuR) and Cold inducible RNA-binding protein (CIRP) influence intestinal mucosal barrier function in ulcerative colitis by competitive regulation on Claudin1

To investigate the effects of RNA-binding proteins cold-inducible RNA binding protein (CIRP) and human antigen R (HuR) on expression of Claudin1 and mucosal barrier function in ulcerative colitis (UC). The clinical specimens of UC patients and healthy volunteers were collected. In the clinical experiments, the expressions of CIRP, Claudin1, and HuR, along with their correlations in tissues of UC patients were analyzed by qRT-PCR, Western blot and Pearson correlation coefficient, respectively. The chi-square test was utilized to assess the relevance between CIRP/HuR/Claudin1 level and clinicopathological characteristics of UC patients. The in vitro and in vivo models of UC were established by lipopolysaccharide treatment or dextran sulfate sodium injection. For cell experiments, after loss- and gain-of-function, the roles of CIRP or HuR in the apoptosis and proliferation of enterocytes were examined by flow cytometry and CCK-8 assay. The intestinal epithelial barrier function was inspected after determination on transepithelial electrical resistance value, horseradish peroxidase permeability and expressions of tight junction proteins (Occludin, ZO-1, and JAM-1). The relationship between HuR, CIRP, and Claudin1 was performed by RNA immunoprecipitation and dual-luciferase reporter gene assay. For in vivo experiments, the disease activity index score, weight loss and colon length of mice were assessed to observe the effect of CIRP or HuR on the UC mouse models. Histological analysis of colon tissues was conducted by H&E staining. FITC-dextran tracking was applied to inspect the intestinal mucosal barrier function of UC mouse models. In this study, high expression of CIRP and low expressions of HuR and Claudin1 were observed in patients, cells and mouse models of UC. The expressions of CIRP, HuR, and Claudin1 were correlated with the severity of patients with UC. There was a negative correlation between CIRP and Claudin1, and as a positive correlation between HuR and Claudin1. Claudin1 can be suppressed by CIRP, while enhanced by HuR. HuR and CIRP can competitively bind to Claudin1. HuR upregulation or CIRP downregulation promoted proliferation, suppressed apoptosis and ameliorated the damage of the barrier function in enterocytes. The in vivo experiments verified that the ameliorated damage of the intestinal mucosal barrier function in UC mice occurred with HuR overexpression or CIRP knockdown. CIRP and HuR confer pivotal effect on the intestinal mucosal barrier function of UC through competitively binding to Claudin1 mRNA.

Fecal microbiota from children with vitamin A deficiency impair colonic barrier function in germ-free mice: The possible role of alterative bile acid metabolites

OBJECTIVE

This study explores the effects of fecal microbiota from children with vitamin A (VA) deficiency on colonic mucosal barrier function.

METHODS

The composition of gut microbes was identified in children with different VA levels, then feces from children with normal VA or VA deficiency was collected separately and transplanted into germ-free (GF) mice, respectively. Three weeks after transplantation, the colon morphology, colonic tight junction proteins, gut microbes, and metabolites were evaluated.

RESULTS

In children, Bifidobacterium and Bacteroides were positively correlated with VA levels. Colonization of VA deficiency fecal microbiota markedly impaired colonic development in GF mice, down-regulated colonic tight junction-related proteins occludin and claudin-1, and reduced immunoglobulin A secretion. Furthermore, fecal microbiota transplantation with different VA levels altered composition of gut microbes and bile acid metabolism pathways in GF mice.

CONCLUSION

These data suggest that fecal microbiota from children with VA deficiency attenuates colonic barrier function in GF mice, which may be achieved by changing the bile acid metabolic pathways.

Interleukin-11-expressing fibroblasts have a unique gene signature correlated with poor prognosis of colorectal cancer

Interleukin (IL)-11 is a member of the IL-6 family of cytokines and is involved in multiple cellular responses, including tumor development. However, the origin and functions of IL-11-producing (IL-11⁺) cells are not fully understood. To characterize IL-11⁺ cells in vivo, we generate Il11 reporter mice. IL-11⁺ cells appear in the colon in murine tumor and acute colitis models. Il11ra1 or Il11 deletion attenuates the development of colitis-associated colorectal cancer. IL-11⁺ cells express fibroblast markers and genes associated with cell proliferation and tissue repair. IL-11 induces the activation of colonic fibroblasts and epithelial cells through phosphorylation of STAT3. Human cancer database analysis reveals that the expression of genes enriched in IL-11⁺ fibroblasts is elevated in human colorectal cancer and correlated with reduced recurrence-free survival. IL-11⁺ fibroblasts activate both tumor cells and fibroblasts via secretion of IL-11, thereby constituting a feed-forward loop between tumor cells and fibroblasts in the tumor microenvironment.

The stromal fibroblast population in the colon is composed of heterogeneous and distinct cell subtypes that play a crucial role in the development of colitis and colon cancer. Here the authors generate IL-11 reporter mice and characterize the origin and phenotype of inflammatory IL-11⁺ fibroblasts in colitis and colon cancer preclinical models.

Complement C5a promotes antigen cross-presentation by Peyer's patch monocyte-derived dendritic cells and drives a protective CD8+ T cell response

The complement fragment C5a is closely associated with adaptive immune induction in the mucosa. However, the mechanisms that control CD8⁺ T cell responses by C5a have not been extensively explored. This study reveals that C5/C5a in the Peyer's patch (PP) subepithelial dome increases upon oral Listeria infection. We hypothesize that C5aR⁺ PP cells play an important role in the induction of antigen-specific T cell immunity. Using single-cell RNA sequencing, we identify C5aR- and lysozyme-expressing dendritic cells (C5aR⁺ LysoDCs) in PP and examine their role in CD8⁺ T cell immune induction. Stimulation of C5aR⁺ LysoDCs by C5a increases reactive oxygen species levels, leading to efficient antigen cross-presentation, which elicits an antigen-specific CD8⁺ T cell response. In C5-deficient mice, oral co-administration of C5a and Listeria enhances Listeria-specific cytotoxic T cell levels. Collectively, these findings suggest a role of the complement system in intestinal T cell immunity.

Mammalian Neuropeptides as Modulators of Microbial Infections: Their Dual Role in Defense versus Virulence and Pathogenesis

The regulation of infection and inflammation by a variety of host peptides may represent an evolutionary failsafe in terms of functional degeneracy and it emphasizes the significance of host defense in survival. Neuropeptides have been demonstrated to have similar antimicrobial activities to conventional antimicrobial peptides with broad-spectrum action against a variety of microorganisms. Neuropeptides display indirect anti-infective capacity via enhancement of the host’s innate and adaptive immune defense mechanisms. However, more recently concerns have been raised that some neuropeptides may have the potential to augment microbial virulence. In this review we discuss the dual role of neuropeptides, perceived as a double-edged sword, with antimicrobial activity against bacteria, fungi, and protozoa but also capable of enhancing virulence and pathogenicity. We review the different ways by which neuropeptides modulate crucial stages of microbial pathogenesis such as adhesion, biofilm formation, invasion, intracellular lifestyle, dissemination, etc., including their anti-infective properties but also detrimental effects. Finally, we provide an overview of the efficacy and therapeutic potential of neuropeptides in murine models of infectious diseases and outline the intrinsic host factors as well as factors related to pathogen adaptation that may influence efficacy.

Distinct Age-Specific miRegulome Profiling of Isolated Small and Large Intestinal Epithelial Cells in Mice

The intestinal epithelium serves as a dynamic barrier to protect the host tissue from exposure to a myriad of inflammatory stimuli in the luminal environment. Intestinal epithelial cells (IECs) encompass differentiated and specialized cell types that are equipped with regulatory genes, which allow for sensing of the luminal environment. Potential inflammatory cues can instruct IECs to undergo a diverse set of phenotypic alterations. Aging is a primary risk factor for a variety of diseases; it is now well-documented that aging itself reduces the barrier function and turnover of the intestinal epithelium, resulting in pathogen translocation and immune priming with increased systemic inflammation. In this study, we aimed to provide an effective epigenetic and regulatory outlook that examines age-associated alterations in the intestines through the profiling of microRNAs (miRNAs) on isolated mouse IECs. Our microarray analysis revealed that with aging, there is dysregulation of distinct clusters of miRNAs that was present to a greater degree in small IECs (22 miRNAs) compared to large IECs (three miRNAs). Further, miRNA-mRNA interaction network and pathway analyses indicated that aging differentially regulates key pathways between small IECs (e.g., toll-like receptor-related cascades) and large IECs (e.g., cell cycle, Notch signaling and small ubiquitin-related modifier pathway). Taken together, current findings suggest novel gene regulation pathways by epithelial miRNAs in aging within the gastrointestinal tissues.

Intestinal Barrier Dysfunction Participates in the Pathophysiology of Ischemic Stroke

The gastrointestinal tract is a major organ for the body to absorb nutrients, water and electrolytes. At the same time, it is a tight barrier to resist the invasion of harmful substances and maintain the homeostasis of the internal environment. Destruction of the intestinal barrier is linked to the digestive system, cardiovascular system, endocrine system and other systemic diseases. Mounting evidence suggests that ischemic stroke not only changes the intestinal microbes, but also increases the permeability of the intestinal barrier, leading to bacterial translocation, infection, and even sepsis. The intestinal barrier, as part of the gut-brain axis, has also been proven to participate in the pathophysiological process of ischemic stroke. However, little attention has been paid to it. Since ischemic stroke is a major public health issue worldwide, there is an urgent need to know more about the disease for better prevention, treatment and prognosis. Therefore, understanding the pathophysiological relationship between ischemic stroke and the intestinal barrier will help researchers further uncover the pathophysiological mechanism of ischemic stroke and provide a novel therapeutic target for the treatment of ischemic stroke. Here, we review the physiology and pathology between ischemic stroke and intestinal barrier based on related articles published in the past ten years about the relationship between ischemic stroke, stroke risk factors and intestinal flora, intestinal barrier, and discuss the following parts: the intestinal barrier; possible mechanisms of intestinal barrier destruction in ischemic stroke; intestinal barrier destruction caused by stroke-related risk factors; intestinal barrier dysfunction in ischemic stroke; targeting the intestinal barrier to improve stroke; conclusions and perspectives.

Akebia saponin D ameliorates metabolic syndrome (MetS) via remodeling gut microbiota and attenuating intestinal barrier injury

Metabolic syndrome (MetS) is a complex, multifactorial disease which lead to an increased risk of cardiovascular disease, type 2 diabetes, and stroke. However, selective, and potent drugs for the treatment of MetS are still lacking. Previous studies have found that Akebia saponin D (ASD) has beneficial effects on metabolic diseases such as obesity, atherosclerosis, and non-alcoholic fatty liver disease (NAFLD). Therefore, our study was designed to determine the effect and mechanism of action of ASD against MetS in a high-fat diet (HFD) induced mouse model. ASD significantly decreased plasma lipid and insulin resistance in these mice, and a targeted approach using metabolomic analyses of plasma and feces indicated that glucose and lipids in these mice crossed the damaged intestinal barrier into circulation. Furthermore, ASD was able to increase lipid excretion and inhibit intestinal epithelial lipid absorption. Results for gut microbiota composition showed that ASD significantly reduced HFD-associated Alistipes, Prevotella, and enhanced the proportions of Butyricimonas, Ruminococcus, and Bifidobacterium. After 14 weeks of ASD/fecal microbiota transplantation (FMT) interventions the developed gut barrier dysfunction was restored. Additionally, RNA-seq revealed that ASD reduced the lipid-induced tight junction (TJ) damage in intestinal epithelial cells via down-regulation of the PPAR-γ-FABP4 pathway in vitro and that use of the PPAR-γ inhibitor (T0070907) was able to partially block the effects of ASD, indicating that the PPAR-γ/FABP4 pathway is a critical mediator involved in the improvement of MetS. Our results demonstrated that ASD not only modifies the gut microbiome but also ameliorates the HFD-induced gut barrier disruption via down-regulation of the PPAR-γ-FABP4 pathway. These findings suggest a promising, and novel therapeutic strategy for gut protection against MetS.

Reflections on the Use of an Invertebrate Chordate Model System for Studies of Gut Microbial Immune Interactions

The functional ecology of the gastrointestinal tract impacts host physiology, and its dysregulation is at the center of various diseases. The immune system, and specifically innate immunity, plays a fundamental role in modulating the interface of host and microbes in the gut. While humans remain a primary focus of research in this field, the use of diverse model systems help inform us of the fundamental principles legislating homeostasis in the gut. Invertebrates, which lack vertebrate-style adaptive immunity, can help define conserved features of innate immunity that shape the gut ecosystem. In this context, we previously proposed the use of a marine invertebrate, the protochordate Ciona robusta, as a novel tractable model system for studies of host-microbiome interactions. Significant progress, reviewed herein, has been made to fulfill that vision. We examine and review discoveries from Ciona that include roles for a secreted immune effector interacting with elements of the microbiota, as well as chitin-rich mucus lining the gut epithelium, the gut-associated microbiome of adults, and the establishment of a large catalog of cultured isolates with which juveniles can be colonized. Also discussed is the establishment of methods to rear the animals germ-free, an essential technology for dissecting the symbiotic interactions at play. As the foundation is now set to extend these studies into the future, broadening our comprehension of how host effectors shape the ecology of these microbial communities in ways that establish and maintain homeostasis will require full utilization of "multi-omics" approaches to merge computational sciences, modeling, and experimental biology in hypothesis-driven investigations.

MyD88 in myofibroblasts enhances colitis-associated tumorigenesis via promoting macrophage M2 polarization

The signal adaptor MyD88, an essential component of TLR signaling, plays an important role in gut-microbiome interactions. However, its contribution to colitis-associated cancer (CAC) is still controversial. Far less is known about the specific effects of MyD88 signaling in myofibroblasts in CAC development. Here, we used a CAC mouse model in which MyD88 was selectively depleted in myofibroblasts. Myofibroblast MyD88-deficient mice are resistant to azoxymethane (AOM)/dextran sodium sulfate (DSS)-induced tumorigenesis, as evidenced by the decrease in the number and sizes of tumors. MyD88 deficiency in myofibroblasts attenuates intestinal epithelial cell (IEC) proliferation after acute DSS-induced colitis. Furthermore, MyD88 signaling in myofibroblasts increases the secretion of osteopontin (OPN), which promotes macrophage M2 polarization through binding to α_vβ₃ and CD44, leading to activation of the STAT3/PPARγ pathway. Thus, MyD88 signaling in myofibroblasts crucially contributes to colorectal cancer development and provides a promising therapeutic target for the prevention of colitis-associated carcinogenesis.

Liver biopsy findings in patients on immune checkpoint inhibitors

Immune checkpoint inhibitors (ICI) can induce a durable response against a wide range of malignancies but cause immune related adverse events. The purpose of this study was to evaluate whether the pattern of inflammation in a liver biopsy in patients on ICIs is likely to be related to ICIs or other causes, and whether the pattern correlates with LFT abnormalities, imaging findings, and responsiveness to steroids. Cancer patients on ICIs who underwent liver biopsy were identified. Clinical data were obtained from electronic records. Liver biopsies were recorded as hepatitic, cholangitic, mixed, steatotic, or as mild nonspecific changes. In total, 28 liver biopsies had a predominantly hepatitic pattern of inflammation, including 11 biopsies with granulomas and 10 with endothelialitis. Eight biopsies had a mixed hepatocytic and cholangitic pattern of injury, including 6 with granulomas and 4 with endothelialitis. Sixteen patients had a predominantly cholangitic pattern, with portal-based inflammation. Three patients had a pattern resembling fatty liver, and five had mild nonspecific changes. The three most common histologic patterns correlated with the pattern of LFT abnormalities. The majority of patients with a cholangitic pattern had competing causes for elevated LFTs, including disease progression or concomitant chemotherapy. The cholangitic pattern was more likely to have bile duct dilatation or narrowing on liver imaging. The pattern of inflammation, degree of lobular injury, or presence of granulomas or endothelialitis did not predict response to steroids or the need for secondary immunosuppression. In this retrospective study, the pattern of inflammation did not predict the need for steroids, the length of time that steroids is required, or the need for secondary immunosuppression. A cholangitic pattern was seen when the pattern of LFTs was cholestatic, and was associated with imaging abnormalities of the bile duct, but a similar pattern was seen in bile duct obstruction and other drug reactions.

Immune Privilege: The Microbiome and Uveitis

Immune privilege (IP), a term introduced to explain the unpredicted acceptance of allogeneic grafts by the eye and the brain, is considered a unique property of these tissues. However, immune responses are modified by the tissue in which they occur, most of which possess IP to some degree. The eye therefore displays a spectrum of IP because it comprises several tissues. IP as originally conceived can only apply to the retina as it contains few tissue-resident bone-marrow derived myeloid cells and is immunologically shielded by a sophisticated barrier – an inner vascular and an outer epithelial barrier at the retinal pigment epithelium. The vascular barrier comprises the vascular endothelium and the glia limitans. Immune cells do not cross the blood-retinal barrier (BRB) despite two-way transport of interstitial fluid, governed by tissue oncotic pressure. The BRB, and the blood-brain barrier (BBB) mature in the neonatal period under signals from the expanding microbiome and by 18 months are fully established. However, the adult eye is susceptible to intraocular inflammation (uveitis; frequency ~200/100,000 population). Uveitis involving the retinal parenchyma (posterior uveitis, PU) breaches IP, while IP is essentially irrelevant in inflammation involving the ocular chambers, uveal tract and ocular coats (anterior/intermediate uveitis/sclerouveitis, AU). Infections cause ~50% cases of AU and PU but infection may also underlie the pathogenesis of immune-mediated “non-infectious” uveitis. Dysbiosis accompanies the commonest form, HLA-B27–associated AU, while latent infections underlie BRB breakdown in PU. This review considers the pathogenesis of uveitis in the context of IP, infection, environment, and the microbiome.

The role of the Hippo pathway in the pathogenesis of inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic and recurrent inflammatory disorder that primarily comprises Crohn's disease (CD) and ulcerative colitis (UC). Owing to its increasing prevalence in Eastern countries and the intractable challenges faced during IBD treatment, extensive research on IBD has been carried out over the last few years. Although the precise aetiology of IBD is undefined, the currently accepted hypothesis for IBD pathogenesis considers it to be a combination of environment, genetic predisposition, gut microbiota, and abnormal immunity. A recently emerged signalling pathway, the Hippo pathway, acts as a key regulator of cell growth, tissue homoeostasis, organ size, and has been implicated in several human cancers. In the past few years, studies have revealed the importance of the Hippo pathway in gastrointestinal tract physiology and gastrointestinal diseases, such as colorectal cancer and IBD. However, the role of the Hippo pathway and its exact impact in IBD remains to be elucidated. This review summarises the latest scientific literature on the involvement of this pathway in IBD from the following perspectives that account for the IBD pathogenesis: intestinal epithelial cell regeneration, immune regulation, gut microbiota, and angiogenesis. A comprehensive understanding of the specific role of the Hippo pathway in IBD will provide novel insights into future research directions and clinical implications of the Hippo pathway.

Combination of polysaccharides from Astragalus membranaceus and Codonopsis pilosula ameliorated mice colitis and underlying mechanisms

ETHNOPHARMACOLOGICAL RELEVANCE

Astragalus membranaceus and Codonopsis pilosula which are two Chinese medicinal herbs are often combinedly used as monarch drugs in Traditional Chinese Medicine (TCM) prescriptions to treat ulcerative colitis (UC). However, the exact mechanisms and effective constituents of the two herbs remain unclear.

AIM OF THE STUDY

Polysaccharides are the main active ingredients of the two medicinal herbs and some specific polysaccharides extracted from the two medicinal herbs have been proven effective in relieving colitis. Hence, we speculated that polysaccharides of the two medicinal herbs may be the material basis for compatibility in TCM prescriptions to treat UC. In the research, total polysaccharides of A. membranaceus and C. pilosula extractum, named AERP and CERP respectively, were administrated to 2.5% dextran sulfate sodium (DSS)-induced acute colitis mice by dosing alone and in combination to test this hypothesis.

MATERIALS AND METHODS

5-aminosalicylic acid (5-ASA, 100 mg/kg/d) was selected as the positive drug. The basic indexes of colitis mice including body weight, stool bleeding, stool consistency and colon lengths were recorded. In addition, tissue inflammatory factors, mucosa-associated proteins, fecal short chain fatty acids (SCFAs) and gut microbiota were also analyzed.

RESULTS

The co-administration of AERP and CERP at specific doses could improve the clinical symptoms, reestablish the immune balance, and alleviate colonic mucosal injury in colitis mice. The unique efficacy of co-administration relied on activation of the aryl hydrocarbon receptor (AhR) and up-regulation of isovaleric acid and butyrate. In addition, the structure of intestinal flora was recovered in the co-administration group.

CONCLUSION

Our research proved the efficacy after co-administration of total polysaccharides from A. membranaceus and C. pilosula on colitis mice which provided a theoretical basis for their compatibility in TCM prescriptions to treat UC.

Alhagi honey polysaccharides attenuate intestinal injury and immune suppression in cyclophosphamide-induced mice

Cyclophosphamide (CY), extensively used as an anti-cancer agent, could cause diverse side effects, such as immunosuppression and intestinal barrier damage. Alhagi honey polysaccharides (AH), polysaccharides isolated from Alhagi honey, are widely known for their anti-tumor and immunomodulatory activities. Herein, AH are evaluated for their ability to protect mice from CY-induced toxicity. The results demonstrated that treatment with AH could prevent the reduction in spleen and thymus indices as well as body weight, and significantly increase the Peyer's patch count in CY-induced mice and the levels of IL-2, IL-6, and TNF-α in serum, suggesting the role of Alhagi honey polysaccharides in alleviating the immunosuppression induced by CY. Moreover, administration of AH significantly increased the SOD activity and the expression level of β-defensin while decreasing the MDA content and DAO activity in CY-treated mice, which suggested a protective effect of AH on the intestinal barrier. Simultaneously, a CY-induced decrease in the ratio of villi length/crypt depth and the number of intraepithelial lymphocytes and goblet cells was reversed by AH treatment, as were the alterations in the expression of ZO-1, mucin-2, E-cadherin and occludin in the intestine and the concentrations of SCFAs in the colon. Furthermore, AH have the ability to regulate the MAPK pathway in CY-mice models to reduce CY-induced toxicity, evidenced by the increased expression of p-ERK and inhibited production of both p-JNK and p-p38. Overall, these results showed that AH could be used as protective agents to mitigate intestinal injury and immune suppression in mice induced by CY.

Regulatory effect of non-starch polysaccharides from purple sweet potato on intestinal microbiota of mice with antibiotic-associated diarrhea

Antibiotic treatment causes antibiotic-associated diarrhea (AAD), which is usually accompanied by disorders of the intestinal flora, aggravating the patient's condition. Recently, more attention has been devoted to the ability of plant polysaccharides to improve the body's flora and enhance immunity. However, reports on whether purple sweet potato polysaccharides (PSPPs) can improve AAD are scarce. This study aimed to extract a non-starch polysaccharide from purple sweet potato and analyze its structure and ability to regulate the intestinal flora of mice with AAD. The diarrhea model was established via intragastric administration of lincomycin and different concentrations of PSPPs (0.1 g kg-1, 0.2 g kg-1, and 0.4 g kg-1) to Balb/C mice. The results showed that PSPP was a pyran polysaccharide with 1 → 2, 1 → 2, 6, 1 → 4, 1 → 4, 6 glycosidic bonds in an α-configuration. In vivo experiments showed that PSPP could relieve diarrhea and improve the structural damage in the ileum caused by lincomycin hydrochloride. In addition, treatment with PSPPs decreased the levels of IL-1β, IL-6 and TNF-α but increased the level of IL-10 in the intestines of mice (p < 0.01). The results of 16S rRNA sequencing showed that PSPPs changed the composition and diversity of the intestinal flora of mice with AAD. In addition, PSPP treatment increased the content of short-chain fatty acids (p < 0.01). These results revealed that PSPPs regulated the intestinal flora, balanced fatty acid metabolism, and relieved the symptoms of diarrhea to a certain extent in mice.

Ileo-colonic lymphoma: presentation, diagnosis, and management

PURPOSE OF REVIEW

The gut-associated lymphoid tissue (GALT), the bulk of which is located in the ileo-colonic region comprises the lymphoid cells of the gastrointestinal tract and confers specific immunological responses. Repetitive antigenic stimulation of these cells predispose to a monoclonal proliferation of this tissue and the eventual development of lymphoma. The gastrointestinal tract is the most commonly involved site of extranodal lymphomas. This review will focus primarily on lymphomas of the ileo-colonic region (defined as the terminal ileum, the colon, and the rectum). We will discuss the epidemiology, pathogenesis, and presentation as well as current practices in diagnosis and management.

RECENT FINDINGS

Despite the majority of the GALT to be located in the ileo-colonic region of the gut, the lymphomas in this location are relatively rare. However, the overall annual incidence of ileo-colonic lymphomas is steadily increasing. This entity has a varied spectrum of clinical presentations. Ileo-colonoscopy with adequate targeted biopsies can serve as a gold standard for definitive diagnosis. Ileo-colonic lymphomas may be managed with chemotherapy alone while surgery is reserved for highly aggressive tumors or clinical emergencies. Radiation is not a preferred adjuvant treatment for lymphomas in this location of the gut. Adequate endoscopic surveillance measures and tools to potentially prevent recurrence and improve the overall prognosis of this disease are lacking.

SUMMARY

Ileo-colonic lymphomas are rare and can present with varied symptoms and signs. Endoscopy with adequate sampling can aid in making a definitive diagnosis. Chemotherapy can be highly effective in management while surgery is indicated for emergency presentations. Adequate endoscopic surveillance tools are lacking, yet imperative to prevent recurrence and improve prognosis.

Hallmarks of Health

Health is usually defined as the absence of pathology. Here, we endeavor to define health as a compendium of organizational and dynamic features that maintain physiology. The biological causes or hallmarks of health include features of spatial compartmentalization (integrity of barriers and containment of local perturbations), maintenance of homeostasis over time (recycling and turnover, integration of circuitries, and rhythmic oscillations), and an array of adequate responses to stress (homeostatic resilience, hormetic regulation, and repair and regeneration). Disruption of any of these interlocked features is broadly pathogenic, causing an acute or progressive derailment of the system coupled to the loss of numerous stigmata of health.

Beneficial effects of Strongyloides venezuelensis antigen extract in acute experimental toxoplasmosis

BACKGROUND

Toxoplasma gondii is a protozoan with worldwide distribution and triggers a strong Th1 immune response in infected susceptible hosts. On the contrary, most helminth infections are characterized by Th2 immune response and the use of helminth-derived antigens to regulate immune response in inflammatory disorders has been broadly investigated.

OBJECTIVES

The aim of this study was to investigate whether treatment with Strongyloides venezuelensis antigen extract (SvAg) would alter immune response against T gondii.

METHODS

C57BL/6 mice were orally infected with T gondii and treated with SvAg, and parasitological, histological and immunological parameters were investigated.

RESULTS

It was observed that SvAg treatment improved survival rates of T gondii-infected mice. At day 7 post-infection, the parasite load was lower in the lung and small intestine of infected SvAg-treated mice than untreated infected mice. Remarkably, SvAg-treated mice infected with T gondii presented reduced inflammatory lesions in the small intestine than infected untreated mice and decreased intestinal and systemic levels of IFN-γ, TNF-α and IL-6. In contrast, SvAg treatment increased T gondii-specific IgA serum levels in infected mice.

CONCLUSIONS

S venezuelensis antigen extract has anti-parasitic and anti-inflammatory properties during T gondii infection suggesting as a possible alternative to parasite and inflammation control.

Noncoding RNA transcription alters chromosomal topology to promote isotype-specific class switch recombination

B cells undergo two types of genomic alterations to increase antibody diversity: introduction of point mutations into immunoglobulin heavy- and light-chain (IgH and IgL) variable regions by somatic hypermutation (SHM) and alteration of antibody effector functions by changing the expressed IgH constant region exons through IgH class switch recombination (CSR). SHM and CSR require the B cell-specific activation-induced cytidine deaminase (AID) protein, the transcription of germline noncoding RNAs, and the activity of the 3' regulatory region (3'RR) super-enhancer. Although many transcription regulatory elements (e.g., promoters and enhancers) reside inside the IgH and IgL sequences, the question remains whether clusters of regulatory elements outside IgH control CSR. Using RNA exosome-deficient mouse B cells where long noncoding RNAs (lncRNAs) are easily detected, we identified a cluster of three RNA-expressing elements that includes lncCSR^IgA (that expresses lncRNA-CSR^IgA). B cells isolated from a mouse model lacking lncRNA-CSR^IgA transcription fail to undergo normal levels of CSR to IgA both in B cells of the Peyer's patches and grown in ex vivo culture conditions. lncRNA-CSR^IgA is expressed from an enhancer site (lncCSR^IgA ) to facilitate the recruitment of regulatory proteins to a nearby CTCF site (CTCF^lncCSR) that alters the chromosomal interactions inside the TAD^lncCSRIgA and long-range interactions with the 3'RR super-enhancer. Humans with IgA deficiency show polymorphisms in the lncCSR^IgA locus compared with the normal population. Thus, we provide evidence for an evolutionarily conserved topologically associated domain (TAD^lncCSRIgA) that coordinates IgA CSR in Peyer's patch B cells through an lncRNA (lncRNA-CSR^IgA) transcription-dependent mechanism.

Recent Insights into Cellular Crosstalk in Respiratory and Gastrointestinal Mucosal Immune Systems

The human body is continuously threatened by pathogens, and the immune system must maintain a balance between fighting infection and becoming over-activated. Mucosal surfaces cover several anatomically diverse organs throughout the body, such as the respiratory and gastrointestinal tracts, and are directly exposed to the external environment. Various pathogens invade the body through mucosal surfaces, making the mucosa the frontline of immune defense. The immune systems of various mucosal tissues display distinctive features that reflect the tissues' anatomical and functional characteristics. This review discusses the cellular components that constitute the respiratory and gastrointestinal tracts; in particular, it highlights the complex interactions between epithelial and immune cells to induce Ag-specific immune responses in the lung and gut. This information on mucosal immunity may facilitate understanding of the defense mechanisms against infectious agents that invade mucosal surfaces, such as severe acute respiratory syndrome coronavirus 2, and provide insight into effective vaccine development.

Metabolites of microbiota response to tryptophan and intestinal mucosal immunity: A therapeutic target to control intestinal inflammation

In a complex, diverse intestinal environment, commensal microbiota metabolizes excessive dietary tryptophan to produce more bioactive metabolites connecting with kinds of diverse process, such as host physiological defense, homeostasis, excessive immune activation and the progression and outcome of different diseases, such as inflammatory bowel disease, irritable bowel syndrome and others. Although commensal microbiota includes bacteria, fungi, and protozoa and all that, they often have the similar metabolites in tryptophan metabolism process via same or different pathways. These metabolites can work as signal to activate the innate immunity of intestinal mucosa and induce the rapid inflammation response. They are critical in reconstruction of lumen homeostasis as well. This review aims to seek the potential function and mechanism of microbiota-derived tryptophan metabolites as targets to regulate and shape intestinal immune function, which mainly focused on two aspects. First, analyze the character of tryptophan metabolism in bacteria, fungi, and protozoa, and assess the functions of their metabolites (including indole and eight other derivatives, serotonin (5-HT) and d-tryptophan) on regulating the integrity of intestinal epithelium and the immunity of the intestinal mucosa. Second, focus on the mediator and pathway for their recognition, transfer and crosstalk between microbiota-derived tryptophan metabolites and intestinal mucosal immunity. Disruption of intestinal homeostasis has been described in different intestinal inflammatory diseases, available data suggest the remarkable potential of tryptophan-derived aryl hydrocarbon receptor agonists, indole derivatives on lumen equilibrium. These metabolites as preventive and therapeutic interventions have potential to promote proinflammatory or anti-inflammatory responses of the gut.

Stratified layer analysis reveals intrinsic leptin stimulates cryptal mesenchymal cells for controlling mucosal inflammation

Mesenchymal cells in the crypt play indispensable roles in the maintenance of intestinal epithelial homeostasis through their contribution to the preservation of stem cells. However, the acquisition properties of the production of stem cell niche factors by the mesenchymal cells have not been well elucidated, due to technical limitations regarding the isolation and subsequent molecular and cellular analyses of cryptal mesenchymal cells. To evaluate the function of mesenchymal cells located at the large intestinal crypt, we established a novel method through which cells are harvested according to the histologic layers of mouse colon, and we compared cellular properties between microenvironmental niches, the luminal mucosa and crypts. The gene expression pattern in the cryptal mesenchymal cells showed that receptors of the hormone/cytokine leptin were highly expressed, and we found a decrease in Wnt2b expression under conditions of leptin receptor deficiency, which also induced a delay in cryptal epithelial proliferation. Our novel stratified layer isolation strategies thus revealed new microenvironmental characteristics of colonic mesenchymal cells, including the intrinsic involvement of leptin in the control of mucosal homeostasis.

Quorum Sensing, Biofilm, and Intestinal Mucosal Barrier: Involvement the Role of Probiotic

The intestine is a particularly dynamic environment in which the host constantly interacts with trillions of symbiotic bacteria called the microbiota. Using quorum sensing (QS) communication, bacteria can coordinate their social behavior and influence host cell activities in a non-invasive manner. Nowadays, a large amount of research has greatly spurred the understanding of how bacterial QS communication regulates bacterial cooperative behaviors due to coexistence and host-microbe interactions. In this review, we discuss bacterial QS in the gut and its role in biofilm formation. As a biological barrier, the mucosal immune system can effectively prevent pathogenic microorganisms and other immunogenic components from entering the internal environment of the host. We focus on the relationship between biofilm and intestinal mucosal immunity, and how probiotic bacteria may regulate them. This review is to provide a theoretical basis for the development of new techniques including probiotics targeting the intestinal barrier function, thereby improving gut health.

Psychological Stress, Intestinal Barrier Dysfunctions, and Autoimmune Disorders: An Overview

Autoimmune disorders (ADs) are multifactorial diseases involving, genetic, epigenetic, and environmental factors characterized by an inappropriate immune response toward self-antigens. In the past decades, there has been a continuous rise in the incidence of ADs, which cannot be explained by genetic factors alone. Influence of psychological stress on the development or the course of autoimmune disorders has been discussed for a long time. Indeed, based on epidemiological studies, stress has been suggested to precede AD occurrence and to exacerbate symptoms. Furthermore, compiling data showed that most of ADs are associated with gastrointestinal symptoms, that is, microbiota dysbiosis, intestinal hyperpermeability, and intestinal inflammation. Interestingly, social stress (acute or chronic, in adult or in neonate) is a well-described intestinal disrupting factor. Taken together, those observations question a potential role of stress-induced defect of the intestinal barrier in the onset and/or the course of ADs. In this review, we aim to present evidences supporting the hypothesis for a role of stress-induced intestinal barrier disruption in the onset and/or the course of ADs. We will mainly focus on autoimmune type 1 diabetes, multiple sclerosis and systemic lupus erythematosus, ADs for which we could find sufficient circumstantial data to support this hypothesis. We excluded gastrointestinal (GI) ADs like coeliac disease to privilege ADs not focused on intestinal disorders to avoid confounding factors. Indeed, GIADs are characterized by antibodies directed against intestinal barrier actors.