Deletion of mucin 2 induces colitis with concomitant metabolic abnormalities in mice

Fucoxanthin Alleviates Dextran Sulfate Sodium-Induced Colitis and Gut Microbiota Dysbiosis in Mice

The purpose of this study was to evaluate the preventive role and underlying mechanisms of fucoxanthin (Fx) on dextran sulfate sodium (DSS)-induced colitis in mice. The present data demonstrated that oral administration of Fx (50 and 200 mg/kg body weight/day) for 36 days significantly alleviated the severity of colitis in DSS-treated mice, as evidenced by attenuating body weight loss, bloody stool, diarrhea, shortened colon length, colonic epithelium distortion, a thin mucus layer, goblet cell depletion, damaged crypts, and extensive infiltration of inflammatory cells in the colonic mucosa. Additionally, Fx notably relieved DSS-induced intestinal epithelial barrier dysfunction via maintaining the tight junction function and preventing excessive apoptosis of colonic epithelial cells. Moreover, Fx effectively diminished colonic inflammation and oxidative stress in DSS-treated mice, and its mechanisms might be due to blunting the activation of NF-κB and NLRP3 inflammasome signaling pathways. Furthermore, Fx also modulates DSS-induced gut microbiota dysbiosis via recovering the richness and diversity of gut microbiota and reshaping the structure of gut microbiota, such as increasing the Firmicutes and Bacteroidota (F/B) ratio and elevating the relative abundance of some potential beneficial bacteria, including Lactobacillaceae and Lachnospiraceae. Overall, Fx might be developed as a promising functional ingredient to prevent colitis and maintain intestinal homeostasis.

Antimicrobial activity of yak beta-defensin 116 against Staphylococcus aureus and its role in gut homeostasis

Staphylococcus aureus (S. aureus) is one of the most common food-borne poisoning microbial agent. However, the antimicrobial activity of β-defensin 116 in yak and its application in S. aureus-induced diarrheal disease have not been reported. In this study, 303 bp cDNA sequence of yak DEFB116 gene was obtained. In addition, the prokaryotic expression vector of DEFB116 protein with a molecular weight of 16 kDa was successfully constructed and expressed. The yak DEFB116 gene can encode 19 amino acids, the percentage of hydrophobic amino acids is 36 % and the total positive charge is 6, which has potential antibacterial potential. Sufficient DEFB116 protein concentration and time can destroy the integrity of the bacterial cell membrane, resulting in leakage of intracellular solutes and thus killing S. aureus. The intestinal histopathological features and the number of inflammatory cells were improved in the diarrhea mouse model under the action of DEFB116 protein. The decrease of goblet cells was reversed, the expression of mucoprotein was increased. DEFB116 protein increased the abundance of Lactobacillus johnsonii, Lactobacillus reuteri and Desulfovibrio, and inhibited the reproduction of pathogenic bacteria. These findings provide new insights into the potential future applications of yak β-defencins in the food industry and medical fields.

The gut mucus network: A dynamic liaison between microbes and the immune system

A complex mucus network made up of large polymers of the mucin-family glycoprotein MUC2 exists between the large intestinal microbial mass and epithelial and immune cells. This has long been understood as an innate immune defense barrier against the microbiota and other luminal threats that reinforces the barrier function of the epithelium and limits microbiota contact with the tissues. However, past and recent studies have provided new evidence of how critical the mucus network is to act as a 'liaison' between host and microbe to mediate anti-inflammatory, mutualistic interactions with the microbiota and protection from pathogens. This review summarizes historical and recent insights into the formation of the gut mucus network, how the microbes and immune system influence mucus, and in turn, how the mucus influences immune responses to the microbiota.

Pro-inflammatory Polarization of Macrophages Causes Intestinal Inflammation in Low-Birth-Weight Piglets and Mice

BACKGROUND

Low-birth-weight (LBW) animals suffer from intestinal damage and inflammation in their early life.

OBJECTIVES

The aim of this study was to investigate the role of macrophages in intestinal inflammation in LBW piglets and mice.

METHODS

Major genes involved in intestinal barrier function such as claudin-1, zonula occludens-1 (ZO-1), occludin, and mucin 2 and inflammatory cytokines such as IL-1β, TNF-α, IL-10, and IL-13 were evaluated in 21-day-old, normal birth weight (NBW) and LBW piglets and mice. Macrophage markers such as CD16/32, CD163, and CD206 were also assessed by immunofluorescence and flow cytometry. Polarized and unpolarized macrophages were further transferred into NBW and LBW mice, followed by evaluation of intestinal permeability and inflammation.

RESULTS

Claudin-1 mRNA in LBW piglets as well as claudin-1, occludin, ZO-1 and mucin 2 mRNAs in LBW mice was significantly downregulated. IL-1β and TNF-α were significantly upregulated in LBW piglets (P < 0.05). LBW mice showed a reduced expression of IL-10 and IL-13 (P < 0.05), with a heightened IL-6 level (P < 0.01) in the jejunum. CD16, a marker for M1 macrophages, was significantly elevated in the jejunum of LBW piglets, whereas CD163, a marker for M2 macrophages, was significantly decreased (P < 0.05). Similarly, LBW mice had more CD11b+CD16/32+ M1 macrophages (P < 0.05) and fewer CD206+ M2 macrophages (P < 0.01) than NBW mice. Moreover, transfer of M1 macrophages exacerbated intestinal inflammation in LBW mice. Furthermore, two major glycolysis-associated genes, hexokinase 2 (HK2) and lactate dehydrogenase A (LDHA), were significantly upregulated in LBW piglets and mice (P < 0.05).

CONCLUSIONS

This study revealed for the first time that the intestinal macrophages are polarized towards a pro-inflammatory phenotype in LBW piglets and mice, contributing to intestinal inflammation. The findings of this study provide new options for the management of intestinal inflammation in LBW animals.

Identification of Critical Modules and Biomarkers of Ulcerative Colitis by Using WGCNA

Background

Ulcerative colitis (UC) is a chronic inflammatory disease of the colon and rectum that has no exact cause and is characterized by relapsing and remitting episodes. We aimed to find biomarkers of UC and its causes.

Methods

We got GSE73661 from the GEO database and used WGCNA to find DEGs that were expressed in the same way in both normal and UC samples. To identify the co-expression modules, we used Weighted Gene Co-Expression Network Analysis. Next, we selected genes that were both DEGs and parts of main modules. Later, three datasets were used to find the hub genes, and qRT-PCR was utilized to confirm the in-silico findings. Additionally, we analyzed the connection between the hub genes and the filtration of immune cells in UC. Using the databases, we made predictions about the miRNAs and lncRNAs that regulate the hub genes and predicted possible therapeutic drugs.

Results

We found 822 DEGs and three main modules related to immunity, endoplasmic reticulum, and metabolism. Using another three datasets and human samples to confirm the mRNA expression of these genes in UC patients, XBP1 and PLPP1 were selected as hub genes, and had excellent diagnostic potential. According to the findings of the immune infiltration, patients with UC exhibited a larger proportion of immune cells. And hub genes, particularly XBP1, were closely linked to a number of immune cell infiltrations. Based on the databases and hub genes, a lncRNA-miRNA-mRNA network, including two miRNAs (miR-214-3p and miR-93-5p), two hub genes, and 124 lncRNAs, and potential therapeutic medicine were identified.

Conclusion

We found two new genes, XBP1 and PLPP1, that are involved in UC and can help diagnose and measure the disease. XBP1 also relates to clinical scores and immune cells. We suggested a gene network and possible drugs based on them.

High Acetate Concentration Protects Intestinal Barrier and Exerts Anti-Inflammatory Effects in Organoid-Derived Epithelial Monolayer Cultures from Patients with Ulcerative Colitis

Short-chain fatty acids as well as their bacterial producers are of increasing interest in inflammatory bowel diseases. Although less studied compared to butyrate, acetate might also be of interest as it may be less toxic to epithelial cells, stimulate butyrate-producing bacteria by cross-feeding, and have anti-inflammatory and barrier-protective properties. Moreover, one of the causative factors of the probiotic potency of Saccharomyces cerevisae var. boulardii is thought to be its high acetate production. Therefore, the objective was to preclinically assess the effects of high acetate concentrations on inflammation and barrier integrity in organoid-based monolayer cultures from ulcerative colitis patients. Confluent organoid-derived colonic epithelial monolayers (n = 10) were exposed to basolateral inflammatory stimulation or control medium. After 24 h, high acetate or control medium was administered apically for an additional 48 h. Changes in TEER were measured after 48 h. Expression levels of barrier genes and inflammatory markers were determined by qPCR. Pro-inflammatory proteins in the supernatant were quantified using the MSD platform. Increased epithelial resistance was observed with high acetate administration in both inflamed and non-inflamed conditions, together with decreased expression levels of IL8 and TNFα and CLDN1. Upon high acetate administration to inflamed monolayers, upregulation of HIF1α, MUC2, and MKI67, and a decrease of the majority of pro-inflammatory cytokines was observed. In our patient-derived human epithelial cell culture model, a protective effect of high acetate administration on epithelial resistance, barrier gene expression, and inflammatory protein production was observed. These findings open up new possibilities for acetate-mediated management of barrier defects and inflammation in IBD.

Dietary adherence to the Mediterranean diet pattern in a randomized clinical trial of patients with quiescent ulcerative colitis

Background

The Mediterranean diet pattern (MDP) is believed to improve health and promote balanced inflammation and metabolism. While unknown, compelling evidence suggests that MDP could benefit patients with inflammatory bowel disease (IBD). We aimed to evaluate the level of diet adherence, diet quality, and nutritional adequacy of the MDP in patients with Ulcerative Colitis (UC).

Methods

Adult participants (n = 32) with quiescent UC were randomized to follow a MDP (n = 18) or Canadian Habitual Diet (CHD) (n = 14) for 12 weeks. The MDP participants received tailored nutrition education from a Registered Dietitian. Demographic, clinical data, medical history, and quality of life were assessed with the Short Inflammatory Bowel Disease Questionnaire (SIBDQ), dietary adherence with the Mediterranean Diet Serving Score (MDSS), diet quality via the Healthy Eating Index-2015 (HEI-2015), and dietary intake (ASA-24) were completed at baseline and week 12.

Results

Participants' diets were analyzed (MDP n = 15, CHD n = 13). The MDP (n = 10, 67%) achieved a high level of adherence (MDSS score between 16 and 24) vs. CHD (n = 3), (p = 0.030). HEI-2015 significantly increased from baseline to week 12 (p = 0.007) in the MDP and was significantly higher at week 12 compared to the CHD (p = 0.0001). The SIBDQ (bowel domain) showed reductions in the passage of large amounts of gas (p = 0.01) and improvements in tenesmus (p = 0.03) in the MDP. Despite enhanced diet quality and adherence in the MDP, females had inadequate intakes of calcium, iron, vitamin D, vitamin E, and choline and males had inadequate intakes of fiber, vitamin D, vitamin E, and choline. No adverse events were reported.

Conclusion

With nutrition education, high adherence to the MDP was achieved without an increase in bowel symptoms. Following the MDP led to a higher diet quality; however, nutritional inadequacies were identified. Tailored dietary education focusing on nutrients of concern when following the MDP is recommended to ensure nutritional adequacy.

Clinical trial registration

[www.ClinicalTrials.gov], identifier [NCT03053713].

Colitis-associated intestinal microbiota regulates brain glycine and host behavior in mice

Inflammatory bowel diseases (IBD) are chronic and relapsing inflammatory disorders of the gastrointestinal tract with complex etiology and no strategies for complete cure. IBD are often complicated by mental disorders like anxiety and depression, indicating substantial shifts in the microbiota gut-brain axis. However, the mechanisms connecting IBD to mental diseases are still under debate. Here we use Muc2 knockout mouse model of chronic colitis to uncouple the effects of the intestinal microbiota on host behavior from chronic inflammation in the gut. Muc2 knockout male mice exhibit high exploratory activity, reduced anxiety-related behaviors, impaired sensorimotor gating, and altered social preference towards males and females. Microbial transfer to wild-type mice via littermate co-housing shows that colitis-associated microbiota rather than inflammation per se defines behavioral features in Muc2 colitis model. Metagenomic profiling and combination of antibiotic treatments revealed that bacterial species Akkermansia muciniphila is associated with the behavioral phenotype in mutants, and that its intestinal abundance correlates with social preference towards males. Metabolomic analysis together with pharmacological inhibition of Gly and NMDA receptors helped us to determine that brain glycine is responsible for the behavioral phenotype in Muc2 mice. Blood and brain metabolic profiles suggest that microbiota-dependent changes in choline metabolism might be involved in regulation of central glycine neurotransmission. Taken together, our data demonstrates that colitis-associated microbiota controls anxiety, sensorimotor gating and social behavior via metabolic regulation of the brain glycinergic system, providing new venues to combat neurological complications of IBD.

Rab11FIP1-deficient mice develop spontaneous inflammation and show increased susceptibility to colon damage

The small GTPase, Rab11a, regulates vesicle trafficking and cell polarity in epithelial cells through interaction with Rab11 family-interacting proteins (Rab11-FIPs). We hypothesized that deficiency of Rab11-FIP1 would affect mucosal integrity in the intestine. Global Rab11FIP1 knockout (KO) mice were generated by deletion of the second exon. Pathology of intestinal tissues was analyzed by immunostaining of colonic sections and RNA-sequencing of isolated colonic epithelial cells. A low concentration of dextran sodium sulfate (DSS, 2%) was added to drinking water for 5 days, and injury score was compared between Rab11FIP1 KO, Rab11FIP2 KO, and heterozygous littermates. Rab11FIP1 KO mice showed normal fertility and body weight gain. More frequent lymphoid patches and infiltration of macrophages and neutrophils were identified in Rab11FIP1 KO mice before the development of rectal prolapse compared with control mice. The population of trefoil factor 3 (TFF3)-positive goblet cells was significantly lower, and the ratio of proliferative to nonproliferative cells was higher in Rab11FIP1 KO colons. Transcription signatures indicated that Rab11FIP1 deletion downregulated genes that mediate stress tolerance response, whereas genes mediating the response to infection were significantly upregulated, consistent with the inflammatory responses in the steady state. Lack of Rab11FIP1 also resulted in abnormal accumulation of subapical vesicles in colonocytes and the internalization of transmembrane mucin, MUC13, with Rab14. After DSS treatment, Rab11FIP1 KO mice showed greater body weight loss and more severe mucosal damage than those in heterozygous littermates. These findings suggest that Rab11FIP1 is important for cytoprotection mechanisms and for the maintenance of colonic mucosal integrity.NEW & NOTEWORTHY Although Rab11FIP1 is important in membrane trafficking in epithelial cells, the gastrointestinal phenotype of Rab11FIP1 knockout (KO) mice had never been reported. This study demonstrated that Rab11FIP1 loss induces mistrafficking of Rab14 and MUC13 and decreases in colonic goblet cells, resulting in impaired mucosal integrity.

A Mediterranean-like fat blend protects against the development of severe colitis in the mucin-2 deficient murine model

There is a growing appreciation that the interaction between diet, the gut microbiota and the immune system contribute to the development and progression of inflammatory bowel disease (IBD). A mounting body of scientific evidence suggests that high-fat diets exacerbate IBD; however, there is a lack of information on how specific types of fat impact colitis. The Mediterranean diet (MD) is considered a health-promoting diet containing approximately 40% total fat. It is not known if the blend of fats found in the MD contributes to its beneficial protective effects. Mice deficient in the mucin 2 gene (Muc 2^-/-) were weaned to 40% fat, isocaloric, isonitrogenous diets. We compared the MD fat blend (high monounsaturated, 2:1 n-6:n-3 polyunsaturated and moderate saturated fat) to diets composed of corn oil (CO, n-6 polyunsaturated-rich), olive oil (monounsaturated-rich) or milk fat (MF, saturated-rich) on spontaneous colitis development in Muc2^-/- mice. The MD resulted in lower clinical and histopathological scores and induced tolerogenic CD103+ CD11b+ dendritic, Th22 and IL-17+ IL-22+ cells necessary for intestinal barrier repair. The MD was associated with beneficial microbes and associated with higher cecal acetic acid levels negatively correlated with colitogenic microbes like Akkermansia muciniphila. In contrast, CO showed a higher prevalence of mucin-degraders including A. muciniphila and Enterobacteriaceae, which have been associated with colitis. A dietary blend of fats mimicking the MD, reduces disease activity, inflammation-related biomarkers and improves metabolic parameters in the Muc2^-/- mouse model. Our findings suggest that the MD fat blend could be incorporated into a maintenance diet for colitis.

Crohn's disease therapeutic dietary intervention (CD-TDI): study protocol for a randomised controlled trial

INTRODUCTION

Dietary patterns that might induce remission in patients with active Crohn's disease (CD) are of interest to patients, but studies are limited in the published literature. We aim to explore the efficacy of the CD therapeutic dietary intervention (CD-TDI), a novel dietary approach developed from best practices and current evidence, to induce clinical and biomarker remission in adult patients with active CD.

METHODS AND ANALYSIS

This study is a 13-week, multicentre, randomised controlled trial in patients with mild-to-moderate active CD at baseline. One hundred and two patients will be block randomised, by sex, 2:1 to the intervention (CD-TDI) or conventional management. Coprimary outcomes are clinical and biomarker remission, defined as a Harvey Bradshaw Index of <5 and a faecal calprotectin of <250 µg/g, respectively.Secondary outcomes include gut microbiota diversity and composition, faecal short-chain fatty acids, regulatory macrophage function, serum and faecal metabolomics, C reactive protein, peripheral blood mononuclear cell gene expression profiles, quality of life, sedentary time and physical activity at 7 and/or 13 weeks. Predictive models of clinical response to a CD-TDI will be investigated.

ETHICS AND DISSEMINATION

The research protocol was approved by the Conjoint Health Research Ethics Board at the University of Calgary (REB19-0402) and the Health Research Ethics Board-Biomedical Panel at the University of Alberta (Pro00090772). Study findings will be presented at national and international conferences, submitted for publication in abstracts and manuscripts, shared on social media and disseminated through patient-education materials.

TRIAL REGISTRATION NUMBER

NCT04596566.

Fat of the Gut: Epithelial Phospholipids in Inflammatory Bowel Diseases

Inflammatory bowel diseases (IBD) comprise a distinct set of clinical symptoms resulting from chronic inflammation within the gastrointestinal (GI) tract. Despite the significant progress in understanding the etiology and development of treatment strategies, IBD remain incurable for thousands of patients. Metabolic deregulation is indicative of IBD, including substantial shifts in lipid metabolism. Recent data showed that changes in some phospholipids are very common in IBD patients. For instance, phosphatidylcholine (PC)/phosphatidylethanolamine (PE) and lysophosphatidylcholine (LPC)/PC ratios are associated with the severity of the inflammatory process. Composition of phospholipids also changes upon IBD towards an increase in arachidonic acid and a decrease in linoleic and a-linolenic acid levels. Moreover, an increase in certain phospholipid metabolites, such as lysophosphatidylcholine, sphingosine-1-phosphate and ceramide, can result in enhanced intestinal inflammation, malignancy, apoptosis or necroptosis. Because some phospholipids are associated with pathogenesis of IBD, they may provide a basis for new strategies to treat IBD. Current attempts are aimed at controlling phospholipid and fatty acid levels through the diet or via pharmacological manipulation of lipid metabolism.