Epithelial IFNγ signalling and compartmentalized antigen presentation orchestrate gut immunity.

All nucleated cells express major histocompatibility complex I and interferon-γ (IFNγ) receptor1, but an epithelial cell-specific function of IFNγ signalling or antigen presentation by means of major histocompatibility complex I has not been explored. We show here that on sensing IFNγ, colonic epithelial cells productively present pathogen and self-derived antigens to cognate intra-epithelial T cells, which are critically located at the epithelial barrier. Antigen presentation by the epithelial cells confers extracellular ATPase expression in cognate intra-epithelial T cells, which limits the accumulation of extracellular adenosine triphosphate and consequent activation of the NLRP3 inflammasome in tissue macrophages. By contrast, antigen presentation by the tissue macrophages alongside inflammasome-associated interleukin-1α and interleukin-1ß production promotes a pathogenic transformation of CD4+ T cells into granulocyte-macrophage colony-stimulating-factor (GM-CSF)-producing T cells in vivo, which promotes colitis and colorectal cancer. Taken together, our study unravels critical checkpoints requiring IFNγ sensing and antigen presentation by epithelial cells that control the development of pathogenic CD4+ T cell responses in vivo.

Conserved γδ T cell selection by BTNL proteins limits progression of human inflammatory bowel disease.

Murine intraepithelial γδ T cells include distinct tissue-protective cells selected by epithelial butyrophilin-like (BTNL) heteromers. To determine whether this biology is conserved in humans, we characterized the colonic γδ T cell compartment, identifying a diverse repertoire that includes a phenotypically distinct subset coexpressing T cell receptor Vγ4 and the epithelium-binding integrin CD103. This subset was disproportionately diminished and dysregulated in inflammatory bowel disease, whereas on-treatment CD103+γδ T cell restoration was associated with sustained inflammatory bowel disease remission. Moreover, CD103+Vγ4+cell dysregulation and loss were also displayed by humans with germline BTNL3/BTNL8 hypomorphism, which we identified as a risk factor for penetrating Crohn's disease (CD). Thus, BTNL-dependent selection and/or maintenance of distinct tissue-intrinsic γδ T cells appears to be an evolutionarily conserved axis limiting the progression of a complex, multifactorial, tissue-damaging disease of increasing global incidence.

Lactobacillus rhamnosus KBL2290 Ameliorates Gut Inflammation in a Mouse Model of Dextran Sulfate Sodium-Induced Colitis.

Ulcerative colitis, a major form of inflammatory bowel disease (IBD) associated with chronic colonic inflammation, may be induced via overreactive innate and adaptive immune responses. Restoration of gut microbiota abundance and diversity is important to control the pathogenesis. Lactobacillus spp., well-known probiotics, ameliorate IBD symptoms via various mechanisms, including modulation of cytokine production, restoration of gut tight junction activity and normal mucosal thickness, and alterations in the gut microbiota. Here, we studied the effects of oral administration of Lactobacillus rhamnosus (L. rhamnosus) KBL2290 from the feces of a healthy Korean individual to mice with DSS-induced colitis. Compared to the dextran sulfate sodium (DSS) + phosphate-buffered saline control group, the DSS + L. rhamnosus KBL2290 group evidenced significant improvements in colitis symptoms, including restoration of body weight and colon length, and decreases in the disease activity and histological scores, particularly reduced levels of pro-inflammatory cytokines and an elevated level of anti-inflammatory interleukin-10. Lactobacillus rhamnosus KBL2290 modulated the levels of mRNAs encoding chemokines and markers of inflammation; increased regulatory T cell numbers; and restored tight junction activity in the mouse colon. The relative abundances of genera Akkermansia, Lactococcus, Bilophila, and Prevotella increased significantly, as did the levels of butyrate and propionate (the major short-chain fatty acids). Therefore, oral L. rhamnosus KBL2290 may be a useful novel probiotic.

Human seminal plasma stimulates the migration of CD11c+ mononuclear phagocytes to the apical side of the colonic epithelium without altering the junctional complexes in an ex vivo human intestinal model.

Introduction: Human immunodeficiency virus type 1 (HIV) transmission mostly occurs through the genital and intestinal mucosae. Although HIV-1 transmission has been extensively investigated, gaps remain in understanding the initial steps of HIV entry through the colonic mucosa. We previously showed that HIV can selectively trigger mononuclear phagocytes (MNP) to migrate within colonic epithelial cells to sample virions. Mucosal exposure to human seminal plasma (HSP), rich in pro- and anti-inflammatory cytokines, chemokines and growth factors, may as well induce alterations of the colonic mucosa and recruit immune cells, hence, affecting pathogen sampling and transmission. Methods: Here, we studied the role of HSP on the paracellular intestinal permeability by analyzing the distribution of two proteins known to play a key role in controlling the intestinal barrier integrity, namely the tight junctions-associated junctional adhesion molecule (JAM-A) and the adherents junction associated protein E-cadherin (E-CAD), by immunofluorescence and confocal microscopy. Also, we evaluated if HSP promotes the recruitment of MNP cells, specifically, the CD11c and CD64 positive MNPs, to the apical side of the human colonic mucosa. At this scope, HSP of HIV-infected and uninfected individuals with known fertility status was tested for cytokines, chemokines and growth factors concentration and used in an ex vivo polarized colonic tissue culture system to mimic as closely as possible the physiological process. Results: HSP showed statistically significant differences in cytokines and chemokines concentrations between the three groups of donors, i.e. HIV infected, or uninfected fertile or randomly identified. Nevertheless, we showed that in the ex vivo tissue culture HSP in general, neither affected the morphological structure of the colonic mucosa nor modulated the paracellular intestinal permeability. Interestingly, CD11c+ MNP cells migrated to the apical surface of the colonic epithelium regardless, if incubated with HIV-infected or -uninfected HSPs, while CD64+ MNP cells, did not change their distribution within the colonic mucosa. Discussion: In conclusion, even if HSP did not perturb the integrity of the human colonic mucosa, it affected the migration of a specific subset of MNPs that express CD11c towards the apical side of the colonic mucosa, which in turn may be involved in pathogen sampling.

Hypoxia Attenuates Colonic Innate Immune Response and Inhibits TLR4/NF-κB Signaling Pathway in Lipopolysaccharide-Induced Colonic Epithelial Injury Mice.

High altitude hypoxia can lead to a spectrum of gastrointestinal problems. As the first line of host immune defense, innate immune response in the intestinal mucosa plays a pivotal role in maintaining intestinal homeostasis and protecting against intestinal injury at high altitude. This study aimed to investigate the effect of hypoxia on the colonic mucosal barrier and toll-like receptor 4 (TLR4)-mediated innate immune responses in the colon. The mice were exposed to a hypobaric chamber to simulate a 5,000 m plateau environment for 7 days, and the colonic mucosa changes were recorded. At the same time, the inflammation model was established by lipopolysaccharide (LPS) to explore the effects of hypoxia on the TLR4/nuclear factor kappa B (NF-κB) signaling pathway and its downstream inflammatory factors [tumor necrosis factor-α, interleukin (IL)-1ß, IL-6, and interferon (IFN)-γ] in the colon. We found that hypoxic exposure caused weight loss and structural disturbance of the colonic mucosa in mice. Compared with the control group, the protein levels of TLR4 [fold change (FC) = 0.75 versus FC = 0.23], MyD88 (FC = 0.80 versus FC = 0.30), TIR-domain-containing adaptor protein inducing interferon-ß (TRIF: FC = 0.89 versus FC = 0.38), and NF-κB p65 (FC = 0.75 versus FC = 0.24) in the colon of mice in the hypobaric hypoxia group were significantly decreased. LPS-induced upregulation of the TLR4/NF-κB signaling and its downstream inflammatory factors was inhibited by hypoxia. Specifically, compared with the LPS group, the protein levels of TLR4 (FC = 1.18, FC = 0.86), MyD88 (FC = 1.20, FC = 0.80), TRIF (FC = 1.20, FC = 0.86), and NF-κB p65 (FC = 1.29, FC = 0.62) and the mRNA levels of IL-1ß (FC = 7.38, FC = 5.06), IL-6 (FC = 16.06, FC = 9.22), and IFN-γ (FC = 2.01, FC = 1.16) were reduced in the hypobaric hypoxia plus LPS group. Our findings imply that hypoxia could lead to marked damage of the colonic mucosa and a reduction of TLR4-mediated colonic innate immune responses, potentially reducing host defense responses to colonic pathogens.

Epithelial chemerin-CMKLR1 signaling restricts microbiota-driven colonic neutrophilia and tumorigenesis by up-regulating lactoperoxidase.

Intestinal barrier immunity is essential for controlling gut microbiota without eliciting harmful immune responses, while its defect contributes to the breakdown of intestinal homeostasis and colitis development. Chemerin, which is abundantly expressed in barrier tissues, has been demonstrated to regulate tissue inflammation via CMKLR1, its functional receptor. Several studies have reported the association between increased expression of chemerin-CMKLR1 and disease severity and immunotherapy resistance in inflammatory bowel disease (IBD) patients. However, the pathophysiological role of endogenous chemerin-CMKLR1 signaling in intestinal homeostasis remains elusive. We herein demonstrated that deficiency of chemerin or intestinal epithelial cell (IEC)-specific CMKLR1 conferred high susceptibility to microbiota-driven neutrophilic colon inflammation and subsequent tumorigenesis in mice following epithelial injury. Unexpectedly, we found that lack of chemerin-CMKLR1 signaling specifically reduced expression of lactoperoxidase (LPO), a peroxidase that is predominantly expressed in colonic ECs and utilizes H2O2 to oxidize thiocyanates to the antibiotic compound, thereby leading to the outgrowth and mucosal invasion of gram-negative bacteria and dysregulated CXCL1/2-mediated neutrophilia. Importantly, decreased LPO expression was causally linked to aggravated microbiota-driven colitis and associated tumorigenesis, as LPO supplementation could completely rescue such phenotypes in mice deficient in epithelial chemerin-CMKLR1 signaling. Moreover, epithelial chemerin-CMKLR1 signaling is necessary for early host defense against bacterial infection in an LPO-dependent manner. Collectively, our study reveals that the chemerin-CMKLR1/LPO axis represents an unrecognized immune mechanism that potentiates epithelial antimicrobial defense and restricts harmful colonic neutrophilia and suggests that LPO supplementation may be beneficial for microbiota dysbiosis in IBD patients with a defective innate antimicrobial mechanism.

Trifolirhizin regulates the balance of Th17/Treg cells and inflammation in the ulcerative colitis mice through inhibiting the TXNIP-mediated activation of NLRP3 inflammasome.

Ulcerative colitis (UC) is a chronic and recurrent autoimmune disease, characterized by recurrence and remission of mucosal inflammation. Although the understanding of the pathogenesis of UC has been improved, effective therapeutic drugs are required for treating patients with UC. In current work, the mouse model of colitis was established. Trifolirhizin was demonstrated to improve symptom in dextran sulfate sodium (DSS)-induced colitis mice. The body weight of mice was elevated, whereas the disease activity index (DAI) was reduced. Moreover, trifolirhizin was involved in inhibition of inflammation and regulation of the balance of T helper 17 (Th 17) cells and regulatory T (Treg) cells in DSS-induced colitis mice. Further, the activation NLRP3 inflammasome was suppressed by trifolirhizin in DSS-induced colitis mice. Trifolirhizin was also identified to regulate AMP-activated protein kinase (AMPK)-thioredoxin-interacting protein (TXNIP) pathway. The trifolirhizin-mediated anti-inflammatory effect was inhibited by suppressing AMPK in DSS-induced UC mice. In summary, the research suggested that administration of trifolirhizin significantly improved the symptoms and the pathological damage in DSS-induced UC mice. Trifolirhizin regulated the balance of Th17/Treg cells and inflammation in the UC mice through inhibiting the TXNIP-mediated activation of NLRP3 inflammasome.

Impact of Caveolin-Mediated Endocytosis on the Trafficking of HIV within the Colonic Barrier.

In the United States, most new cases of human immunodeficiency virus (HIV) belong to the at-risk group of gay and bisexual men. Developing therapies to reverse viral latency and prevent spread is paramount for the HIV cure agenda. In gay and bisexual men, a major, yet poorly characterized, route of HIV entry is via transport across the colonic epithelial barrier. While colonic tears and paracellular transport contribute to infection, we hypothesize that HIV entry through the colonic mucosa proceeds via a process known as transcytosis, involving (i) virion binding to the apical surface of the colonic epithelium, (ii) viral endocytosis, (iii) transport of virions across the cell, and (iv) HIV release from the basolateral membrane. Using Caco-2 colonic epithelial cells plated as a polarized monolayer in transwells, we characterized the mechanism of HIV transport. After exposing the monolayer to HIV apically, reverse transcription quantitative PCR (RT-qPCR) of the viral genome present in the basolateral chamber revealed that transport is dose dependent, cooperative, and inefficient, with released virus first detectable at 12 h. Inefficiency may be associated with >50% decline in detectable intracellular virus that correlates temporally with increased association of the virion with lysosomal-associated membrane protein 1 (LAMP-1+) endosomes. Microscopy revealed green fluorescent protein (GFP)-labeled HIV within the confines of the epithelial monolayer, with no virus detectable between cells, suggesting that viral transport is transcellular. Treatment of the monolayer with endocytosis inhibitors, cholesterol reducing agents, and small interfering RNA (siRNA) to caveolin showed that viral endocytosis is mediated by caveolin-coated endosomes contained in lipid rafts. These results indicate that HIV transport across the intestinal epithelial barrier via transcytosis is a viable mechanism for viral spread and a potential therapeutic target. IMPORTANCE Despite the success of combination antiretroviral therapy in suppressing HIV replication and the emergence and effectiveness of PrEP-based prevention strategies, in 2018, 37,968 people in the United States received a new HIV diagnosis, accompanied by 15,820 deaths. While the annual number of new diagnoses decreased 7% from 2014 to 2018, 14% of people with HIV did not know they were infected. Gay and bisexual men accounted for 69% of all HIV diagnoses and 83% of diagnoses among males. Due to the scope of the HIV epidemic, determining and understanding precise routes of infection and the mechanisms of viral spread are paramount to ending the epidemic. Since transcellular transport of HIV across an intact colonic epithelial barrier is poorly understood, our overall goal is to characterize the molecular events involved in HIV transcytosis across the intestinal epithelial cell.

Presence of Natural Killer B Cells in Simian Immunodeficiency Virus-Infected Colon That Have Properties and Functions Similar to Those of Natural Killer Cells and B Cells but Are a Distinct Cell Population.

Here, we report the appearance of natural killer B (NKB) cells within the colon during simian immunodeficiency virus (SIV) infection of susceptible monkeys. Using RNA sequencing (RNAseq) and flow cytometry, we show that NKB cells are unique cells with features and functions of both NK and B cells. NKB cells express receptors and ligands found on B cells that are important for (i) antigen presentation; (ii) activities associated with class switching, affinity maturation, and B-cell memory formation in secondary lymphoid follicles; and (iii) antigen recognition. The predominant immunoglobulins (Igs) expressed on NKB cells are IgA, although NKB cells can express surface IgM and IgG. There is dominant lambda expression over the kappa light chain characteristic of mucosal B cells. In addition to B-cell aspects, NKB cells express NK cell activation receptors and Fas ligand. We show in this study that NKB cells express perforin and granzymes and lyse cells in a lytic assay. In addition to NK cell cytolytic function, NKB cells also produce the inflammatory cytokines interferon gamma, tumor necrosis factor alpha, and interleukin-18 (IL-18). Finally, we noted the increased capacity of NKB cells to proliferate compared to NK cells and CD8+ T cells from the SIV-infected colon. The increased proliferation and inflammatory cytokine production may be related to the relatively high expression levels of IL-15 receptor beta, IL-7 receptor, IL-18 receptor, and 41BB relative to the same receptors on CD8 and NK cells. The properties of NKB cells may point to their role in the enhanced inflammation observed in the SIV-infected gut. IMPORTANCE There is low-level but significant mucosal inflammation in the gastrointestinal tract secondary to human immunodeficiency virus (HIV) infection that has long-term consequences for the infected host. This inflammation most likely originates from the immune response that appears as a consequence of HIV. Here, we show in an animal model of HIV that the chronically SIV-infected gut contains cytotoxic natural killer B cells that produce inflammatory cytokines and proliferate during infection.

Integrated Analysis of Ulcerative Colitis Revealed an Association between PHLPP2 and Immune Infiltration.

Ulcerative colitis (UC) is a progressive intestine inflammatory disease that is prone to recur. Herein, we utilize microarray technology and bioinformatics to reveal the underlying pathogenesis of UC and provide novel markers. Colonic biopsies were taken from eight UC patients and eight healthy controls. Three differentially expressed miRNAs (DEMIs) and 264 differentially expressed genes (DEGs) were screened using mRNA and miRNA microarray. Most DEGs were significantly associated with immune response and were markedly enriched in the IL-17 signaling pathway. Among the target genes of DEMIs, PHLPP2 overlapped with DEGs and the downregulation of PHLPP2 group was mainly involved in the epithelial-mesenchymal transition. PHLPP2 was downregulated in UC patients, which was validated in 5 GEO datasets and qRT-PCR. The ROC curve demonstrated that PHLPP2 has a perfect ability to distinguish UC patients from healthy controls. Moreover, PHLPP2 was low expression in patients with active UC. CIBERSORT algorithm indicated that the abundance of gamma delta T cells (P = 0.04), M0 macrophages (P = 0.01), and activated mast cells (P < 0.01) was significantly greater than that of the control group. The Spearman correlation analysis showed that PHLPP2 was positively correlated with the proportion of activated NK cells (rho = 0.62, P = 0.013) and Tregs (rho = 0.55, P = 0.03), but negatively correlated with those of activated mast cells (rho = -0.8, P < 0.01) and macrophages (rho = -0.73, P < 0.01). These results indicate that PHLPP2 is associated with immune cells in the pathogenesis of UC, as well as provide new prospects and future directions of investigation.

Single-cell transcriptomic analysis of human colonic macrophages reveals niche-specific subsets.

Macrophages are a heterogeneous population of cells involved in tissue homeostasis, inflammation, and cancer. Although macrophages are densely distributed throughout the human intestine, our understanding of how gut macrophages maintain tissue homeostasis is limited. Here we show that colonic lamina propria macrophages (LpMs) and muscularis macrophages (MMs) consist of monocyte-like cells that differentiate into multiple transcriptionally distinct subsets. LpMs comprise subsets with proinflammatory properties and subsets with high antigen-presenting and phagocytic capacity. The latter are strategically positioned close to the surface epithelium. Most MMs differentiate along two trajectories: one that upregulates genes associated with immune activation and angiogenesis, and one that upregulates genes associated with neuronal homeostasis. Importantly, MMs are located adjacent to neurons and vessels. Cell-cell interaction and gene network analysis indicated that survival, migration, transcriptional reprogramming, and niche-specific localization of LpMs and MMs are controlled by an extensive interaction with tissue-resident cells and a few key transcription factors.

Colon stroma mediates an inflammation-driven fibroblastic response controlling matrix remodeling and healing.

Chronic inflammation is often associated with the development of tissue fibrosis, but how mesenchymal cell responses dictate pathological fibrosis versus resolution and healing remains unclear. Defining stromal heterogeneity and identifying molecular circuits driving extracellular matrix deposition and remodeling stands to illuminate the relationship between inflammation, fibrosis, and healing. We performed single-cell RNA-sequencing of colon-derived stromal cells and identified distinct classes of fibroblasts with gene signatures that are differentially regulated by chronic inflammation, including IL-11-producing inflammatory fibroblasts. We further identify a transcriptional program associated with trans-differentiation of mucosa-associated fibroblasts and define a functional gene signature associated with matrix deposition and remodeling in the inflamed colon. Our analysis supports a critical role for the metalloprotease Adamdec1 at the interface between tissue remodeling and healing during colitis, demonstrating its requirement for colon epithelial integrity. These findings provide mechanistic insight into how inflammation perturbs stromal cell behaviors to drive fibroblastic responses controlling mucosal matrix remodeling and healing.

Identification of an ACK1/TNK2-based prognostic signature for colon cancer to predict survival and inflammatory landscapes.

Activated Cdc42-associated kinase 1 (ACK1), a kind of tyrosine kinase, is considered to be an oncogene in many cancers, and it is likely to become a potential target for cancer treatment. We found that the expression of the ACK1 gene in colon cancer was higher than that in normal tissues adjacent to cancer, and high expression of the ACK1 gene was associated with poor prognosis of patients. We assessed the prognosis of colon cancer based on ACK1-related genes and constructed a model that can predict the prognosis of colon cancer patients in colon cancer data from The Cancer Genome Atlas (TCGA) database. We then explored the relationship between ACK1 and the immune microenvironment of colon cancer. The overexpression of ACK1 might hinder the function of antigen-presenting cells. The colon cancer prognosis prediction model we constructed has certain significance for clinicians to judge the prognosis of patients with colon cancer. The expression of the ACK1 gene might affect the infiltration level of a variety of immune cells and immunomodulators in the immune microenvironment.

Integrated bioinformatics and network pharmacology to identify the therapeutic target and molecular mechanisms of Huangqin decoction on ulcerative Colitis.

Huangqin decoction (HQD) is a Traditional Chinese Medicine formula for ulcerative colitis. However, the pharmacology and molecular mechanism of HQD on ulcerative colitis is still unclear. Combined microarray analysis, network pharmacology, and molecular docking for revealing the therapeutic targets and molecular mechanism of HQD against ulcerative colitis. TCMSP, DrugBank, Swiss Target Prediction were utilized to search the active components and effective targets of HQD. Ulcerative colitis effective targets were obtained by microarray data from the GEO database (GSE107499). Co-targets between HQD and ulcerative colitis are obtained by Draw Venn Diagram. PPI (Protein-protein interaction) network was constructed by the STRING database. To obtain the core target, topological analysis is exploited by Cytoscape 3.7.2. GO and KEGG enrichment pathway analysis was performed to Metascape platform, and molecular docking through Autodock Vina 1.1.2 finished. 161 active components with 486 effective targets of HQD were screened. 1542 ulcerative colitis effective targets were obtained with |Log2FC|> 1 and adjusted P-value < 0.05. The Venn analysis was contained 79 co-targets. Enrichment analysis showed that HQD played a role in TNF signaling pathway, IL-17 signaling pathway, Th17 cell differentiation, etc. IL6, TNF, IL1B, PTGS2, ESR1, and PPARG with the highest degree from PPI network were successfully docked with 19 core components of HQD, respectively. According to ZINC15 database, quercetin (ZINC4175638), baicalein (ZINC3871633), and wogonin (ZINC899093) recognized as key compounds of HQD on ulcerative colitis. PTGS2, ESR1, and PPARG are potential therapeutic targets of HQD. HQD can act on multiple targets through multi-pathway, to carry out its therapeutic role in ulcerative colitis.

IL-17RD/sef exacerbates experimental mouse colitis and inflammation-associated tumorigenesis by regulating the proportion of T cell subsets.

T helper cells, especially Th1 and Th17 cells, were reported to play a pivotal role in the pathogenesis of inflammatory bowel disease (IBD). However, the underlying factors regulating T cell functions in IBD progression remain to be fully elucidated. Here, we revealed that IL-17RD/Sef exacerbates DSS-induced colitis by regulating the balance of T cell subsets and their secretion of associated cytokines. We also observed that IL-17RD/Sef promotes colitis-associated tumorigenesis and negatively correlates with survival in both mouse and colorectal cancer patients. Our results suggested that IL-17RD/Sef functions as a regulator of T cell subsets to promote the inflammatory responses in the pathogenesis of IBD and colitis-associated colon cancer.

GPR15-C10ORF99 functional pairing initiates colonic Treg homing in amniotes.

Regulatory T lymphocyte (Treg) homing reactions mediated by G protein-coupled receptor (GPCR)-ligand interactions play a central role in maintaining intestinal immune homeostasis by restraining inappropriate immune responses in the gastrointestinal tract. However, the origin of Treg homing to the colon remains mysterious. Here, we report that the C10ORF99 peptide (also known as CPR15L and AP57), a cognate ligand of GPR15 that controls Treg homing to the colon, originates from a duplication of the flanking CDHR1 gene and is functionally paired with GPR15 in amniotes. Evolutionary analysis and experimental data indicate that the GPR15-C10ORF99 pair is functionally conserved to mediate colonic Treg homing in amniotes and their expression patterns are positively correlated with herbivore diet in the colon. With the first herbivorous diet in early amniotes, a new biological process (herbivorous diet short-chain fatty acid-C10ORF99/GPR15-induced Treg homing colon immune homeostasis) emerged, and we propose an evolutionary model whereby GPR15-C10ORF99 functional pairing has initiated the first colonic Treg homing reaction in amniotes. Our findings also highlight that GPCR-ligand pairing leads to physiological adaptation during vertebrate evolution.

Weilan gum oligosaccharide ameliorates dextran sulfate sodium­induced experimental ulcerative colitis.

Ulcerative colitis (UC) is a global disease, characterized by periods of relapse that seriously affects the quality of life of patients. Oligosaccharides are considered to be a prospective strategy to alleviate the symptoms of UC. The present study aimed to evaluate the effect of weilan gum oligosaccharide (WLGO) on a mouse UC model induced by dextran sulfate sodium (DSS). WLGO structural physical properties were characterized by electrospray mass spectrometry and fourier tansform infrared spectroscopy. MTT assays were performed to evaluate the non­toxic concentration of WLGO. RT­qPCR and ELISAs were conducted to determine the levels of inflammatory factors. The clinical symptoms and mucosal integrity of the DSS­induced UC model were assessed by DAI and histological assessment. LPS­induced Caco­2 cells and DSS­induced UC mice were used to explore the effects of WLGO on UC. Treatment of the mice with 4.48 g/kg/day WLGO via gavage for 7 days significantly relieved the symptoms of DSS­induced UC model mice, whereas significant effects were not observed for all symptoms of DSS­induced UC in the WLGO­low group. The disease activity index score was decreased and the loss of body weight was reduced in DSS­induced UC model mice treated with WLGO. Moreover, colonic damage and abnormally short colon length shortenings were relieved following WLGO treatment. WLGO treatment also reduced the concentration and mRNA expression levels of proinflammatory cytokines, including interleukin­1ß, interleukin­6 and tumor necrosis factor α, in DSS­induced UC model mice and lipopolysaccharide­treated Caco­2 cells. These results indicated that WLGO may be an effective strategy for UC treatment.

Ten-week high fat and high sugar diets in mice alter gut-brain axis cytokines in a sex-dependent manner.

Diets high in fat and sugar induce inflammation throughout the body, particularly along the gut-brain axis; however, the way these changes in immune signaling mediate one another remains unknown. We investigated cytokine changes in the brain and colon following prolonged high fat or sugar diet in female and male adult C57BL/6 mice. Ten weeks of high fat diet increased levels of TNFα, IL-1ß, IL-6, IFNγ, and IL-10 in the female hippocampus and altered cytokines in the frontal cortex of both sexes. High sugar diet increased hippocampal cytokines and decreased cytokines in the diencephalon and frontal cortex. In the colon, high fat diet changed cytokine expression in both sexes, while high sugar diet only increased TNFα in males. Causal mediation analysis confirmed that colon IL-10 and IL-6 mediate high fat diet-induced neuroimmune changes in the female hippocampus and male frontal cortex. Additionally, high fat diet increased food consumption and weight gain in both sexes, while high sugar diet decreased male weight gain. These findings reveal a novel causal link between gut and brain inflammation specific to prolonged consumption of high fat, not high sugar, diet. Importantly, this work includes females which have been under-represented in diet research, and demonstrates that diet-induced neuroinflammation varies by brain region between sexes. Furthermore, our data suggest female brains are more vulnerable than males to inflammatory changes following excessive fat and sugar consumption, which may help explain the increased risk of inflammation-associated psychiatric conditions in women who eat a Western Diet rich in both dietary components.

Polydopamine Nanoparticle-Mediated Dopaminergic Immunoregulation in Colitis.

Despite immunosuppression is critical for reducing immune overactivation, existing immunosuppressive agents are largely restricted by low inhibition efficiencies and unpredictable off-target toxicities. Here, the use of the dopaminergic system is reported to suppress hyperactive immune responses in local inflamed tissues. A polydopamine nanoparticular immunosuppressant (PDNI) is synthesized to stimulate regulatory T (Treg) cells and directly inhibit T helper 1 (Th1), Th2, and Th17 cells. Moreover, PDNI can inhibit the activation of dendritic cells to upregulate the ratio of Treg/Th17, which assists the reversion of inflammatory responses. The application of dopaminergic immunoregulation is further disclosed by combining with gut microbiota modulation for treating inflammations. The combination is implemented by coating living beneficial bacteria with PDNI. Following oral delivery, coated bacteria not only suppress the hyperactive immune responses but also positively modulate the gut microbiome in mice characterized with colitis. Strikingly, the combination demonstrates enhanced treatment efficacies in comparison with clinical aminosalicylic acid in two murine models of colitis. The use of the dopaminergic system opens a window to intervene immune responses and provides a versatile platform for the development of new therapeutics for treating inflammatory diseases.

Short-Chain Fatty Acid Decreases the Expression of CEBPB to Inhibit miR-145-Mediated DUSP6 and Thus Further Suppresses Intestinal Inflammation.

Intestinal inflammation is a common disease which can further lead to inflammatory bowel disease and even intestinal cancer. The increasing focus has come to the role of short-chain fatty acid (SCFA) in various bowel diseases. Hence, this study was designed to explore the specific role of SCFA in intestinal inflammation. In vivo and in vitro models of intestinal inflammation were constructed by lipopolysaccharide (LPS) injection in mice and LPS treatment on intestinal epithelial cells. A possible regulatory mechanism involving SCFA, CCAAT enhancer-binding protein beta (CEBPB), microRNA-145 (miR-145), and dual-specificity phosphatase 6 (DUSP6) in intestinal inflammation was verified by ChIP assay and dual-luciferase reporter gene assay. To evaluate the effects of SCFA on LPS-treated intestinal epithelial cells, the expression of relevant genes and inflammatory factors (IL-6, TNF-α, and IL-1ß) were determined. Last, the role of SCFA in vivo was explored through the scoring of disease activity index (DAI) and observation of colonic histology of LPS-treated mice. SCFA decreased the CEBPB expression in mouse colon tissues and small intestine epithelial cells induced by LPS. Furthermore, CEBPB could bind to the miR-145 promoter to inhibit its expression, thereby promoting the expression of DUSP6. In addition, SCFA improved the DAI, colonic histology, and the expression of serum inflammatory factors in LPS-treated mice and cells, noting that SCFA alleviated intestinal inflammation in vitro and in vivo. To sum up, SCFA inhibited DUSP6 by upregulating miR-145 through CEBPB repression and thus prevented the development of intestinal inflammation.