MUC genes are differently expressed during onset and maintenance of inflammation in dextran sodium sulfate-treated mice

Safflower polysaccharide ameliorates acute ulcerative colitis by regulating STAT3/NF-κB signaling pathways and repairing intestinal barrier function

This study is to investigate the effect of SPS on the UC model. An animal model of UC induced by DSS was developed using C57BL/6 mice. The body weight was recorded every day, and the symptoms related to UC were detected. H&E staining, AB-PAS staining and PSR staining were used to evaluate the histopathological changes of the colon. Inflammation and mucosal barrier indicators were detected by qRT-PCR, and the 16 S rRNA sequence was used to detect the intestinal flora. SPS can significantly prevent and treat DSS-induced ulcerative colitis in animals. SPS significantly improved clinical symptoms, alleviated pathological damage, inhibited the infiltration of intestinal inflammatory cells. SPS treatment can protect goblet cells, enhance the expression of tight junction proteins and mucins, inhibit the expression of antimicrobial peptides, thereby improving intestinal barrier integrity. The prevention and treatment mechanism of SPS may be related to the inhibition of STAT3/NF-κB signaling pathway to regulate intestinal barrier function. In particular, SPS also significantly adjusted the structure of intestinal flora, significantly increasing the abundance of Akkermansia and Limosilactobacillus and inhibiting the abundance of Bacteroides. Overall, SPS has a significant therapeutic effect on ulcerative colitis mice, and is expected to play its value effectively in clinical treatment.

Digital spatial profiling identifies molecular changes involved in development of colitis-associated colorectal cancer

Objective

Chronic colonic inflammation seen in inflammatory bowel disease (IBD) is a risk factor for colorectal cancer (CRC). Colitis-associated cancers (CAC) are molecularly different from sporadic CRC. This study aimed to evaluate spatially defined molecular changes associated with neoplastic progression to identify mechanisms of action and potential biomarkers for prognostication.

Design

IBD patients who had undergone colectomy for treatment of their IBD or dysplasia were identified from an institutional database. Formalin-fixed paraffin embedded samples from areas of normal, inflamed, dysplastic and adenocarcinoma tissue were identified for digital spatial profiling using the Nanostring GeoMx™ Cancer Transcriptome Atlas. RNA expression and quantification of 1812 genes was measured and analysed in a spatial context to compare differences in gene expression.

Results

Sixteen patients were included, nine patients had CAC, two had dysplasia only and five had colitis only. Significant, step-wise differences in gene expression were seen between tissue types, mainly involving progressive over-expression of collagen genes associated with stromal remodelling. Similarly, MYC over-expression was associated with neoplastic progression. Comparison of normal and inflamed tissue from patients who progressed to those who did not also showed significant differences in immune-related genes, including under-expression of thte chemokines CCL18, CCL25 and IL-R7, as well as CD3, CD6 and lysozyme. The known oncogene CD24 was significantly overexpressed.

Conclusion

Both tissue types and patient groups are molecularly distinguishable on the basis of their gene expression patterns. Further prospective work is necessary to confirm these differences and establish their clinical significance and potential utility as biomarkers.

Preventive Effect of Ecklonia cava Extract on DSS-Induced Colitis by Elevating Intestinal Barrier Function and Improving Pathogenic Inflammation

Inflammatory bowel disease (IBD), including ulcerative colitis and Crohn's disease, is a complex gastrointestinal disorder with a multifactorial etiology, including environmental triggers, autoimmune mechanisms, and genetic predisposition. Despite advancements in therapeutic strategies for IBD, its associated mortality rate continues to rise, which is often attributed to unforeseen side effects of conventional treatments. In this context, we explored the potential of Ecklonia cava extract (ECE), derived from an edible marine alga known for its anti-inflammatory and antioxidant properties, in mitigating IBD. This study investigated the effectiveness of ECE as a preventive agent in a murine model of dextran sulfate sodium (DSS)-induced colitis. Our findings revealed that pretreatment with ECE significantly ameliorated colitis severity, as evidenced by increased colon length, reduced spleen weight, and histological improvements demonstrated by immunohistochemical analysis. Furthermore, ECE significantly attenuated the upregulation of inflammatory cytokines and mediators and the infiltration of immune cells known to be prominent features of colitis in mice. Notably, ECE alleviated dysbiosis of intestinal microflora and aided in the recovery of damaged intestinal mucosa. Mechanistically, ECE exhibited protective effects against pathogenic colitis by inhibiting the NLRP3/NF-κB pathways known to be pivotal regulators in the inflammatory signaling cascade. These compelling results suggest that ECE holds promise as a potential candidate for IBD prevention. It might be developed into a functional food for promoting gastrointestinal health. This research sheds light on the preventive potential of natural compounds like ECE in the management of IBD, offering a safer and more effective approach to combating this challenging disease.

Intestinal homeostasis disruption in mice chronically exposed to arsenite-contaminated drinking water

Chronic exposure to inorganic arsenic [As(III) and As(V)] affects about 200 million people, and is linked to a greater incidence of certain types of cancer. Drinking water is the main route of exposure, so, in endemic areas, the intestinal mucosa is constantly exposed to the metalloid. However, studies on the intestinal toxicity of inorganic As are scarce. The objective of this study was to evaluate the toxicity of a chronic exposure to As(III) on the intestinal mucosa and its associated microbiota. For this purpose, BALB/c mice were exposed during 6 months through drinking water to As(III) (15 and 30 mg/L). Treatment with As(III) increased reactive oxygen species (43-64%) and lipid peroxidation (8-51%). A pro-inflammatory response was also observed, evidenced by an increase in fecal lactoferrin (23-29%) and mucosal neutrophil infiltration. As(III) also induced an increase in the colonic levels of pro-inflammatory cytokines (24-201%) and the activation of some pro-inflammatory signaling pathways. Reductions in the number of goblet cells and mucus production were also observed. Moreover, As(III) exposure resulted in changes in gut microbial alpha diversity but no differences in beta diversity. This suggested that the abundance of some taxa was significantly affected by As(III), although the composition of the population did not show significant alterations. Analysis of differential taxa agreed with this, 21 ASVs were affected in abundance or variability, especially ASVs from the family Muribaculaceae. Intestinal microbiota metabolism was also affected, as reductions in fecal concentration of short-chain fatty acids were observed. The effects observed on different components of the intestinal barrier may be responsible of the increased permeability in As(III) treated mice, evidenced by an increase in fecal albumin (48-66%). Moreover, serum levels of Lipopolysaccharide binding proteins and TNF-α were increased in animals treated with 30 mg/L of As(III), suggesting a low-level systemic inflammation.

Diet-mediated metaorganismal relay biotransformation: health effects and pathways

In recent years, the concept of metaorganism expands our insight into how diet-microbe-host interactions contribute to human health and diseases. We realized that many biological metabolic processes in the host can be summarized into metaorganismal relay pathways, in which metabolites such as trimethylamine-N‑oxide, short-chain fatty acids and bile acids act as double-edged swords (beneficial or harmful effects) in the initiation and progression of diseases. Pleiotropic effects of metabolites are derived from several influencing factors including dose level, targeted organ of effect, action duration and species of these metabolites. Based on the pleiotropic effects of metabolites, personalized therapeutic approaches including microecological agents, enzymatic regulators and changes in dietary habits to govern related metabolite production may provide a new insight in promoting human health. In this review, we summarize our current knowledge of metaorganismal relay pathways and elaborate on the pleiotropic effects of metabolites in these pathways, with special emphasis on related therapeutic nutritional interventions.

Selection strategy of dextran sulfate sodium-induced acute or chronic colitis mouse models based on gut microbial profile

BACKGROUND

Dextran sulfate sodium (DSS) replicates ulcerative colitis (UC)-like colitis in murine models. However, the microbial characteristics of DSS-triggered colitis require further clarification. To analyze the changes in gut microbiota associated with DSS-induced acute and chronic colitis.

METHODS

Acute colitis was induced in mice by administering 3% DSS for 1 week in the drinking water, and chronic colitis was induced by supplementing drinking water with 2.5% DSS every other week for 5 weeks. Control groups received the same drinking water without DSS supplementation. The histopathological score and length of the colons, and disease activity index (DAI) were evaluated to confirm the presence of experimental colitis. Intestinal microbiota was profiled by 16S rDNA sequencing of cecal content.

RESULTS

Mice with both acute and chronic DSS-triggered colitis had significantly higher DAI and colon histopathological scores in contrast to the control groups (P < 0.0001, P < 0.0001), and the colon was remarkably shortened (P < 0.0001, P < 0.0001). The gut microbiota α-diversity was partly downregulated in both acute and chronic colitis groups in contrast to their respective control groups (Pielou index P = 0.0022, P = 0.0649; Shannon index P = 0.0022, P = 0.0931). The reduction in the Pielou and Shannon indices were more obvious in mice with acute colitis (P = 0.0022, P = 0.0043). The relative abundance of Bacteroides and Turicibacter was increased (all P < 0.05), while that of Lachnospiraceae, Ruminococcaceae, Ruminiclostridium, Rikenella, Alistipes, Alloprevotella, and Butyricicoccus was significantly decreased after acute DSS induction (all P < 0.05). The relative abundance of Bacteroides, Akkermansia, Helicobacter, Parabacteroides, Erysipelatoclostridium, Turicibacter and Romboutsia was also markedly increased (all P < 0.05), and that of Lachnospiraceae_NK4A136_group, Alistipes, Enterorhabdus, Prevotellaceae_UCG-001, Butyricicoccus, Ruminiclostridium_6, Muribaculum, Ruminococcaceae_NK4A214_group, Family_XIII_UCG-001 and Flavonifractor was significantly decreased after chronic DSS induction (all P < 0.05).

CONCLUSION

DSS-induced acute and chronic colitis demonstrated similar symptoms and histopathological changes. The changes in the gut microbiota of the acute colitis model were closer to that observed in UC. The acute colitis model had greater abundance of SCFAs-producing bacteria and lower α-diversity compared to the chronic colitis model.

Trefoil Factor Family (TFF) Peptides and Their Links to Inflammation: A Re-evaluation and New Medical Perspectives

Trefoil factor family peptides (TFF1, TFF2, TFF3), together with mucins, are typical exocrine products of mucous epithelia. Here, they act as a gastric tumor suppressor (TFF1) or they play different roles in mucosal innate immune defense (TFF2, TFF3). Minute amounts are also secreted as endocrine, e.g., by the immune and central nervous systems. As a hallmark, TFF peptides have different lectin activities, best characterized for TFF2, but also TFF1. Pathologically, ectopic expression occurs during inflammation and in various tumors. In this review, the role of TFF peptides during inflammation is discussed on two levels. On the one hand, the expression of TFF1-3 is regulated by inflammatory signals in different ways (upstream links). On the other hand, TFF peptides influence inflammatory processes (downstream links). The latter are recognized best in various Tff-deficient mice, which have completely different phenotypes. In particular, TFF2 is secreted by myeloid cells (e.g., macrophages) and lymphocytes (e.g., memory T cells), where it modulates immune reactions triggering inflammation. As a new concept, in addition to lectin-triggered activation, a hypothetical lectin-triggered inhibition of glycosylated transmembrane receptors by TFF peptides is discussed. Thus, TFFs are promising players in the field of glycoimmunology, such as galectins and C-type lectins.

Anti-inflammatory Bifidobacterium strains prevent dextran sodium sulfate induced colitis and associated gut microbial dysbiosis in mice

Crohn’s and ulcerative colitis are common inflammatory conditions associated with Inflammatory bowel disease. Owing to the importance of diet based approaches for the prevention of inflammatory gut conditions, the present study was aimed to screen the human isolates of Bifidobacterium strains based on their ability to reduce LPS-induced inflammation in murine macrophage (RAW 264.7) cells and to evaluate prioritized strains for their preventive efficacy against ulcerative colitis in mice. Twelve out of 25 isolated strains reduced the production of LPS-induced nitric oxide and inflammatory cytokines. Furthermore, three strains, B. longum Bif10, B. breve Bif11, and B. longum Bif16 conferred protection against dextran sodium sulfate induced colitis in mice. The three strains prevented shortening of colon, spleen weight, percentage body weight change and disease activity index relative to colitis mice. Lower levels of Lipocalin-2, TNF-α, IL-1β and IL-6 and improved SCFA levels were observed in Bifidobacterium supplemented mice relative to DSS counterparts. Bacterial composition of B. longum Bif10 and B. breve Bif11 fed mice was partly similar to the normal mice, while DSS and B. longum Bif16 supplemented mice showed deleterious alterations. At the genus level, Bifidobacterium supplementation inhibited the abundances of pathobionts such as Haemophilus, Klebsiella and Lachnospira there by conferring protection.

A single early-in-life antibiotic course increases susceptibility to DSS-induced colitis

Background

There is increasing evidence that the intestinal microbiota plays a crucial role in the maturation of the immune system and the prevention of diseases during childhood. Early-life short-course antibiotic use may affect the progression of subsequent disease conditions by changing both host microbiota and immunologic development. Epidemiologic studies provide evidence that early-life antibiotic exposures predispose to inflammatory bowel disease (IBD).

Methods

By using a murine model of dextran sodium sulfate (DSS)-induced colitis, we evaluated the effect on disease outcomes of early-life pulsed antibiotic treatment (PAT) using tylosin, a macrolide and amoxicillin, a beta-lactam. We evaluated microbiota effects at the 16S rRNA gene level, and intestinal T cells by flow cytometry. Antibiotic-perturbed or control microbiota were transferred to pups that then were challenged with DSS.

Results

A single PAT course early-in-life exacerbated later DSS-induced colitis by both perturbing the microbial community and altering mucosal immune cell composition. By conventionalizing germ-free mice with either antibiotic-perturbed or control microbiota obtained 40 days after the challenge ended, we showed the transferrable and direct effect of the still-perturbed microbiota on colitis severity in the DSS model.

Conclusions

The findings in this experimental model provide evidence that early-life microbiota perturbation may increase risk of colitis later in life.

Non-canonical HIF-1 stabilization contributes to intestinal tumorigenesis

The hypoxia-inducible transcription factor HIF-1 is appreciated as a promising target for cancer therapy. However, conditional deletion of HIF-1 and HIF-1 target genes in cells of the tumor microenvironment can result in accelerated tumor growth, calling for a detailed characterization of the cellular context to fully comprehend HIF-1's role in tumorigenesis. We dissected cell type-specific functions of HIF-1 for intestinal tumorigenesis by lineage-restricted deletion of the Hif1a locus. Intestinal epithelial cell-specific Hif1a loss reduced activation of Wnt/β-catenin, tumor-specific metabolism and inflammation, significantly inhibiting tumor growth. Deletion of Hif1a in myeloid cells reduced the expression of fibroblast-activating factors in tumor-associated macrophages resulting in decreased abundance of tumor-associated fibroblasts (TAF) and robustly reduced tumor formation. Interestingly, hypoxia was detectable only sparsely and without spatial association with HIF-1α, arguing for an importance of hypoxia-independent, i.e., non-canonical, HIF-1 stabilization for intestinal tumorigenesis that has not been previously appreciated. This adds a further layer of complexity to the regulation of HIF-1 and suggests that hypoxia and HIF-1α stabilization can be uncoupled in cancer. Collectively, our data show that HIF-1 is a pivotal pro-tumorigenic factor for intestinal tumor formation, controlling key oncogenic programs in both the epithelial tumor compartment and the tumor microenvironment.

High-fat diet reduces the level of secretory immunoglobulin A coating of commensal gut microbiota

Excessive fat intake is associated with changes in gut microbiota composition. In the present study, we focused on the secretory immunoglobulin A (SIgA) coating of gut microbiota as a mucosal immune response affecting the gut microbiota following a high-fat diet (HFD). The level of SIgA coating of gut microbiota was evaluated in normal-fat diet (NFD)- and HFD-fed mice. HFD significantly decreased the level of SIgA coating the gut microbiota compared with NFD. Of note, substitution of HFD with NFD resulted in a complete recovery of the level of SIgA coating. These findings suggest that dietary fat influences the SIgA coating of the gut microbiota. Furthermore, we analyzed the composition of the gut microbiota and the concentration of cecal short-chain fatty acids. HFD feeding changed the gut microbiota composition at the phylum and family levels. Pearson correlation analysis between the level of SIgA coating of gut microbiota and the relative abundance of gut microbiota showed that the relative abundances of Clostridiaceae, Mogibacteriaceae, Turicibacteraceae, and Bifidobacteriaceae were negatively correlated with the level of SIgA coating of gut microbiota. Conversely, the relative abundances of Desulfovibrionaceae, S24-7, and Lactobacillaceae were positively correlated with the level of SIgA coating. The concentrations of cecal acetate and butyrate were lower in HFD-fed mice and positively correlated with the level of SIgA coating of gut microbiota. Our observations suggest that a decrease in the level of SIgA coating of the gut microbiota through a HFD might relate to HFD-induced changes in microbial composition and microbial metabolites production.

Attenuating effect of melatonin on lipopolysaccharide-induced chicken small intestine inflammation

Enriched melatonin (MEL) has been found in the mammalian intestine and has been recently demonstrated to alleviate rodent colitis. In this study, the effect of MEL on lipopolysaccharide (LPS)-induced intestinal inflammations was investigated in new chicken hatchlings. The chicks were fed with a diet supplemented with MEL (12.5 mg/day) from D1 to D10. Meanwhile, the chicks in the LPS or MEL + LPS groups were injected with LPS (10 mg/kg BW, i.p.) at D10. LPS treatment for 6 h increased the expression of IL-6, IL-4, caspase-3 mRNAs and TUNEL-positive cell populations, but decreased populations of the goblet and PCNA+ cells, IgA production and the expression of MUC2 mRNA in the duodenum. Compared with the LPS group, MEL pre-feeding alleviated duodenal inflammation and decreased the expression of TNF-α mRNAs by 23.6% (P = 0.004), IL-6 mRNAs by 69.4% (P = 0.001), IL-4 mRNAs by 4.1% (P = 0.824) and caspase-3 mRNAs by 45.8% (P < 0.001). Conversely, MEL pre-feeding attenuated the LPS-induced changes of IgA production by 161.6% (P = 0.013) and PCNA+ cell populations by 172.1% (P < 0.001) in the duodenum. TLR4 mRNA was also up-regulated by LPS treatment but down-regulated by MEL pre-feeding. In conclusion, dietary MEL could attenuate LPS-induced chick duodenal inflammation by down-regulating the expression of inflammatory cytokines, promoting epithelial cell proliferation, improving the immunological barrier and inhibiting epithelial apoptosis via the mediation of TLR4.

Expression of Mucins and Claudins in the Colon during Acute and Chronic Experimental Colitis

We studied changes in the expression of mRNA for mucins and claudins in the medial part of the colon in male C57Bl/6 mice on the model of acute and chronic colitis induced by substitution of drinking water with 1% solution of dextran sodium sulphate for 5 days. In acute colitis, the expression of the main structural component of glycocalyx, mucin Muc3, decreased and expression of pore-forming claudin Cldn2 increased, which reflected enhanced permeability of tight junctions. In the chronic colitis group, in comparison with the normal group, we observed an increase in expression of mRNA of main structural mucus component Muc2, enhanced of expression of Muc1 associated with carcinogenesis, and reduced expression of Muc13, which led to a more severe course of colitis; the expression of pore-forming claudin Cldn2 was elevated. These findings indicate that the imbalance in the expression of mucins and claudins plays an important role in the mechanisms of development of acute and chronic colitis.

Blend of organic acids and medium chain fatty acids prevents the inflammatory response and intestinal barrier dysfunction in mice challenged with enterohemorrhagic Escherichia coli O157:H7

Impaired epithelial barrier function disrupts immune homeostasis and increases inflammation in intestines, leading to many intestinal diseases. The blend of organic acids (OAs) and medium chain fatty acids (MCFAs) has been shown to have synergistic bactericidal effect. In this study, we demonstrated that two blends of OAs and MCFAs (OM1 and OM2) could prevent the inflammatory response and intestinal barrier dysfunction in enterohemorrhagic Escherichia coli (EHEC)-infected mice. Treatments of OM1 and OM2 significantly reduced the body weight loss and production of IL-6 and TNF-α induced by EHEC. Mice treated with OM1 and OM2 showed decrease in serum D-lactic concentration, DAO activity and bacterial transfer to liver and spleen. Furthermore, OM1 and OM2 increased the expression of tight junction proteins occludin and ZO-1, mucus protein MUC-2, and host defense peptides mBD1, mBD2 and mBD3. Finally, OM1 and OM2 increased the population of Lactobacillus spp. and Bifidobacterium spp., but decreased that of E. coli in the cecum. These findings indicate that OM1 and OM2 may be used to develop a prophylactic agent for intestinal inflammation and injury in enteric pathogen infection.

Navy and black bean supplementation attenuates colitis-associated inflammation and colonic epithelial damage

The enriched levels of nondigestible fermentable carbohydrates and phenolic compounds found in common beans can exert immunomodulatory effects within the colon that improve gut health and mitigate the severity of colitis-associated inflammatory pathology. Prior to acute colitis onset, C57Bl/6 mice were prefed isocaloric 20% cooked navy bean (NB) or black bean (BB) diets for 3 weeks and switched to control basal diet (BD) 24 h prior to colitis induction via 5-day exposure to dextran sodium sulfate (2% w/v in drinking water)+3 days of fresh water. The severity of the acute colitis phenotype was attenuated by bean prefeeding, evidenced by reduced colon tissue inflammatory transcription factor activation (NFκB, STAT3) and inflammatory mediator levels in the colon (IL-1β, IL-6, IL-18 and MCP-1) and serum (TNFα, IL-6, IL-1β, MCP-1) versus BD (P≤.05). Additionally, biomarkers of enhanced wound repair responses were increased by bean prefeeding including colon tissue protein levels of IL-22, IL-27 and activated (i.e., GTP-bound) Cdc42 and Rac1 versus BD (P≤.05). mRNA expressions of genes involved in normal colonic epithelial function and the promotion of epithelial barrier integrity, defense and/or restitution and wound closure including MUC1, RELMβ, IgA and REG3γ were all increased in NB and BB prefed mice versus BD (P≤.05). Collectively, bean supplementation prior to colitis induction (i.e., mimicking disease relapse) primes the colonic microenvironment to attenuate the severity of the colitis inflammatory phenotype and maintain aspects of epithelial barrier function.

Role of short-chain fatty acids in colonic inflammation, carcinogenesis, and mucosal protection and healing

Short-chain fatty acids (SCFAs), mainly acetate, propionate, and butyrate, produced by microbial fermentation of undigested food substances are believed to play a beneficial role in human gut health. Short-chain fatty acids influence colonic health through various mechanisms. In vitro and ex vivo studies show that SCFAs have anti-inflammatory and anticarcinogenic effects, play an important role in maintaining metabolic homeostasis in colonocytes, and protect colonocytes from external harm. Animal studies have found substantial positive effects of SCFAs or dietary fiber on colonic disease, but convincing evidence in humans is lacking. Most human intervention trials have been conducted in the context of inflammatory bowel disease. Only a limited number of those trials are of high quality, showing little or no favorable effect of SCFA treatment over placebo. Opportunities for future research include exploring the use of combination therapies with anti-inflammatory drugs, prebiotics, or probiotics; the use of prodrugs in the setting of carcinogenesis; or the direct application of SCFAs to improve mucosal healing after colonic surgery.

Dextran sodium sulfate colitis murine model: An indispensable tool for advancing our understanding of inflammatory bowel diseases pathogenesis

Inflammatory bowel diseases (IBD), including Crohn’s disease and ulcerative colitis, are complex diseases that result from the chronic dysregulated immune response in the gastrointestinal tract. The exact etiology is not fully understood, but it is accepted that it occurs when an inappropriate aggressive inflammatory response in a genetically susceptible host due to inciting environmental factors occurs. To investigate the pathogenesis and etiology of human IBD, various animal models of IBD have been developed that provided indispensable insights into the histopathological and morphological changes as well as factors associated with the pathogenesis of IBD and evaluation of therapeutic options in the last few decades. The most widely used experimental model employs dextran sodium sulfate (DSS) to induce epithelial damage. The DSS colitis model in IBD research has advantages over other various chemically induced experimental models due to its rapidity, simplicity, reproducibility and controllability. In this manuscript, we review the newer publicized advances of research in murine colitis models that focus upon the disruption of the barrier function of the intestine, effects of mucin on the development of colitis, alterations found in microbial balance and resultant changes in the metabolome specifically in the DSS colitis murine model and its relation to the pathogenesis of IBD.

Initial Gut Microbial Composition as a Key Factor Driving Host Response to Antibiotic Treatment, as Exemplified by the Presence or Absence of Commensal Escherichia coli

Antibiotics are important for treating bacterial infection; however, efficacies and side effects of antibiotics vary in medicine and experimental models. A few studies have correlated microbiota composition variations with health outcomes in response to antibiotics; however, no study has demonstrated causality. We had noted variation in colonic expression of C-type lectins, regenerating islet-derived protein 3β (Reg3β) and Reg3γ, after metronidazole treatment in a mouse model. To investigate the effects of specific variations in the preexisting microbiome on host response to antibiotics, mice harboring a normal microbiota were allocated to 4 treatments in a 2-by-2 factorial arrangement with or without commensal Escherichia coli and with or without metronidazole in drinking water. E. coli colonized readily without causing a notable shift in the microbiota or host response. Metronidazole administration reduced microbiota biodiversity, indicated by decreased Chao1 and Shannon index values, and altered microbiota composition. However, the presence of E. coli strongly affected metronidazole-induced microbiota shifts. Remarkably, this single commensal bacterium in the context of a complex population led to variations in host responses to metronidazole treatment, including increased expression of antimicrobial peptides Reg3β and Reg3γ and intestinal inflammation indicated by tumor necrosis factor alpha levels. Similar results were obtained from 2-week antibiotic exposure and with additional E. coli isolates. The results of this proof-of-concept study indicate that even minor variations in initial commensal microbiota can drive shifts in microbial composition and host response after antibiotic administration. As well as providing an explanation for variability in animal models using antibiotics, the findings encourage the development of personalized medication in antibiotic therapies.IMPORTANCE This work provides an understanding of variability in studies where antibiotics are used to alter the gut microbiota to generate a host response. Furthermore, although providing evidence only for the one antibiotic, the study demonstrated that initial gut microbial composition is a key factor driving host response to antibiotic administration, creating a compelling argument for considering personalized medication based on individual variations in gut microbiota.

Intestinal anti-inflammatory activity of Ground Cherry (Physalis angulata L.) standardized CO2 phytopharmaceutical preparation

AIM

To investigate the effects of Ground Cherry (Physalis angulata L.) standardized supercritical CO₂ extract in trinitrobenzenesulphonic acid (TNBS) model of rat intestinal inflammation.

METHODS

The animals were divided into groups that received vehicle or P. angulata extract (PACO₂) orally at the doses 25, 50 and 100 mg/kg daily by 5 d before TNBS damage. Protective effects of PACO₂ were assessed by macroscopic analysis, biochemical determinations of the levels of myeloperoxidase (MPO), alkaline phosphatase (ALP), glutathione and cytokines (such as INF-γ, IL-1β, IL-6, IL-10 and TNF-α), gene expression evaluation (including Hsp70, heparanase, NF-κB, mitogen-activated protein kinases (Mapk) 1, 3, 6 and 9, and the mucins genes Muc 1, 2, 3 and 4) and histopathological studies using optical, and electronic (transmission and scanning) microscopy.

RESULTS

PACO₂ extract promoted a significant reduction in MPO and ALP activities, reducing oxidative stress and neutrophil infiltration. These effects were accompanied by significant reduction of colonic levels of IFN-γ and IL-6 and down-regulation of heparanase, Hsp70, Mapk3, Mapk9, Muc1 and Muc2 genes expression when compared with TNBS-control animals. In addition, protective effects were also evidenced by reduced neutrophil infiltration, recovery of cell architecture and replacement of mucin by histopathological and ultrastructural analysis.

CONCLUSION

Physalis angulata supercritical CO₂ extract is an intestinal anti-inflammatory product that modulates oxidative stress, immune response and expression of inflammatory mediators, with potentially utility for treating inflammatory bowel disease.

Immunological effects of reduced mucosal integrity in the early life of BALB/c mice

Certain stimuli at the gut barrier may be necessary in early life to establish a proper balance of immune tolerance. We evaluated a compromised barrier in juvenile mice in relation to microbiota and local and systemic immunity. BALB/c mice were treated with a low dose of dextran sulfate sodium (DSS) with or without ampicillin and lipopolysaccharide (LPS) to clarify the importance of microbial antigens and interaction between microbial-associated patterns and toll-like receptors. The barrier breach resulted in increased plasma LPS, which was highest in mice treated simultaneously with ampicillin. Adding LPS in the food reduced its levels in plasma. Regulatory T cells were acutely increased in mesenteric lymph nodes (MLN) and spleen during DSS treatment regardless of simultaneous ampicillin treatment. In contrast, NK T and NK cells decreased in MLN and in spleen. This acute DSS effect was reflected in fold changes of haptoglobin and Il1a in colon, and this was also more pronounced in mice simultaneously treated with ampicillin. On day 1 post-treatment, major upregulations of Ifng, Foxp3, Il1b, Il2, and Il6 genes in colon were only observed in the mice simultaneously treated with ampicillin. A two-fold upregulation of colonic Foxp3 and Il1a was evident 25 days post-treatment. DSS skewed the microbiota in favor of Gram negative phyla. Therefore, increased permeability induced tolerogenic immunity independent of microbiota, and this was enhanced by LPS stimulation.

Dietary tryptophan alleviates dextran sodium sulfate-induced colitis through aryl hydrocarbon receptor in mice

Ulcerative colitis is the typical progression of chronic inflammatory bowel disease. Amino acids, particularly tryptophan, have been reported to exert a protective effect against colitis induced by dextran sodium sulfate (DSS), but the precise underlying mechanisms remain incompletely clarified. Tryptophan metabolites are recognized to function as endogenous ligands for aryl hydrocarbon receptor (Ahr), which is a critical regulator of inflammation and immunity. Thus, we conducted this study to investigate whether dietary tryptophan supplementation protects against DSS-induced colitis by acting through Ahr. Female wild-type (WT) and Ahr-deficient (knockout; KO) mice (10-12 weeks old) were divided into four groups and fed either a control or 0.5% tryptophan diet. The tryptophan diet ameliorated DSS-induced colitis symptoms and severity in WT mice but not in KO mice, and the diet reduced the mRNA expression of Il-6, Tnfα, Il-1β and the chemokines Ccl2, Cxcl1 and Cxcl2 in the WT groups. Furthermore, Il-22 and Stat3 mRNA expression in the colon was elevated in WT mice fed with the tryptophan diet, which mainly protected epithelial layer integrity, and Ahr also modulated immune homeostasis by regulating Foxp3 and Il-17 mRNA expression. These data suggest that tryptophan-containing diet might ameliorate DSS-induced acute colitis and regulate epithelial homeostasis through Ahr. Thus, tryptophan could serve as a promising preventive agent in the treatment of ulcerative colitis.

Cathelicidin-WA Improves Intestinal Epithelial Barrier Function and Enhances Host Defense against Enterohemorrhagic Escherichia coli O157:H7 Infection

Impaired epithelial barrier function disrupts immune homeostasis and increases inflammation in intestines, leading to many intestinal diseases. Cathelicidin peptides suppress intestinal inflammation and improve intestinal epithelial barrier function independently of their antimicrobial activity. In this study, we investigated the effects of Cathelicidin-WA (CWA) on intestinal epithelial barrier function, as well as the underlying mechanism, by using enterohemorrhagic Escherichia coli (EHEC)-infected mice and intestinal epithelial cells. The results showed that CWA attenuated EHEC-induced clinical symptoms and intestinal colitis, as did enrofloxacin (Enro). CWA decreased IL-6 production in the serum, jejunum, and colon of EHEC-infected mice. Additionally, CWA alleviated the EHEC-induced disruption of mucin-2 and goblet cells in the intestine. Interestingly, CWA increased the mucus layer thickness, which was associated with increasing expression of trefoil factor 3, in the jejunum of EHEC-infected mice. CWA increased the expression of tight junction proteins in the jejunum of EHEC-infected mice. Using intestinal epithelial cells and a Rac1 inhibitor in vitro, we demonstrated that the CWA-mediated increases in the tight junction proteins might depend on the Rac1 pathway. Furthermore, CWA improved the microbiota and short-chain fatty acid concentrations in the cecum of EHEC-infected mice. Although Enro and CWA had similar effects on intestinal inflammation, CWA was superior to Enro with regard to improving intestinal epithelial barrier and microbiota in the intestine. In conclusion, CWA attenuated EHEC-induced inflammation, intestinal epithelial barrier damage, and microbiota disruption in the intestine of mice, suggesting that CWA may be an effective therapy for many intestinal diseases.

Purified rutin and rutin-rich asparagus attenuates disease severity and tissue damage following dextran sodium sulfate-induced colitis

SCOPE

This study investigated the effects of cooked whole asparagus (ASP) versus its equivalent level of purified flavonoid glycoside, rutin (RUT), on dextran sodium sulfate (DSS)-induced colitis and subsequent colitis recovery in mice.

METHODS AND RESULTS

C57BL/6 male mice were fed an AIN-93G basal diet (BD), or BD supplemented with 2% cooked ASP or 0.025% RUT for 2 wks prior to and during colitis induction with 2% DSS in water for 7 days, followed by 5 days colitis recovery. In colitic mice, both ASP and RUT upregulated mediators of improved barrier integrity and enhanced mucosal injury repair (e.g. Muc1, IL-22, Rho-A, Rac1, and Reg3γ), increased the proportion of mouse survival, and improved disease activity index. RUT had the greatest effect in attenuating DSS-induced colonic damage indicated by increased crypt and goblet cell restitution, reduced colonic myeloperoxidase, as well as attenuated DSS-induced microbial dysbiosis (reduced Enterobacteriaceae and Bacteroides, and increased unassigned Clostridales, Oscillospira, Lactobacillus, and Bifidobacterium).

CONCLUSION

These findings demonstrate that dietary cooked ASP and its flavonoid glycoside, RUT, may be useful in attenuating colitis severity by modulating the colonic microenvironment resulting in reduced colonic inflammation, promotion of colonic mucosal injury repair, and attenuation of colitis-associated microbial dysbiosis.

Diets enriched with cranberry beans alter the microbiota and mitigate colitis severity and associated inflammation

Common beans are rich in phenolic compounds and nondigestible fermentable components, which may help alleviate intestinal diseases. We assessed the gut health priming effect of a 20% cranberry bean flour diet from two bean varieties with differing profiles of phenolic compounds [darkening (DC) and nondarkening (NDC) cranberry beans vs. basal diet control (BD)] on critical aspects of gut health in unchallenged mice, and during dextran sodium sulfate (DSS)-induced colitis (2% DSS wt/vol, 7 days). In unchallenged mice, NDC and DC increased (i) cecal short-chain fatty acids, (ii) colon crypt height, (iii) crypt goblet cell number and mucus content and (iv) Muc1, Klf4, Relmβ and Reg3γ gene expression vs. BD, indicative of enhanced microbial activity and gut barrier function. Fecal 16S rRNA sequencing determined that beans reduced abundance of the Lactobacillaceae (Ruminococcus gnavus), Clostridiaceae (Clostridium perfringens), Peptococcaceae, Peptostreptococcaceae, Rikenellaceae and Pophyromonadaceae families, and increased abundance of S24-7 and Prevotellaceae. During colitis, beans reduced (i) disease severity and colonic histological damage, (ii) increased gene expression of barrier function promoting genes (Muc1-3, Relmβ, and Reg3γ) and (iii) reduced colonic and circulating inflammatory cytokines (IL-1β, IL-6, IFNγ and TNFα). Therefore, prior to disease induction, bean supplementation enhanced multiple concurrent gut health promoting parameters that translated into reduced colitis severity. Moreover, both bean diets exerted similar effects, indicating that differing phenolic content did not influence the endpoints assessed. These data demonstrate a proof-of-concept regarding the gut-priming potential of beans in colitis, which could be extended to mitigate the severity of other gut barrier-associated pathologies.

Dietary flaxseed modulates the colonic microenvironment in healthy C57Bl/6 male mice which may alter susceptibility to gut-associated diseases

Understanding how dietary components alter the healthy baseline colonic microenvironment is important in determining their roles in influencing gut health and gut-associated diseases. Dietary flaxseed (FS) has demonstrated anti-colon cancer effects in numerous rodent models, however, exacerbated acute colonic mucosal injury and inflammation in a colitis model. This study investigates whether FS alters critical aspects of gut health in healthy unchallenged mice, which may help explain some of the divergent effects observed following different gut-associated disease challenges. Four-week-old C57Bl/6 male mice were fed an AIN-93G basal diet (BD) or an isocaloric BD+10% ground FS diet for 3 weeks. FS enhanced colon goblet cell density, mucus production, MUC2 mRNA expression, and cecal short chain fatty acid levels, indicative of beneficial intestinal barrier integrity responses. Additionally, FS enhanced colonic regenerating islet-derived protein 3 gamma (RegIIIγ) and reduced MUC1 and resistin-like molecule beta (RELMβ) mRNA expression which may indicate altered responses in regulating microbial defense and injury repair responses. FS diet altered the fecal microbial community structure (16S rRNA gene profiling), including a 20-fold increase in Prevotella spp. and a 30-fold reduction in Akkermansia muciniphila abundance. A 10-fold reduction in A. muciniphila abundance by FS was also demonstrated in the colon tissue-associated microbiota (quantitative PCR). Furthermore, fecal branched chain fatty acids were increased by FS, indicative of increased microbial-derived putrefactive compounds. In conclusion, consumption of a FS-supplemented diet alters the baseline colonic microenvironment of healthy mice which may modify subsequent mucosal microbial defense and injury-repair responses leading to altered susceptibility to different gut-associated diseases.

Mice deficient in Muc4 are resistant to experimental colitis and colitis-associated colorectal cancer

MUC4, a large transmembrane mucin normally expressed in the small and large intestine, is differentially expressed during inflammatory and malignant conditions of the colon. However, the expression pattern and the role of MUC4 in colitis and colorectal cancer (CRC) are inconclusive. Therefore, the aim of this study was to understand the role of Muc4 during inflammatory and malignant conditions of the colon. Here, we generated Muc4(-/-) mice and addressed its role in colitis and colitis-associated CRC using dextran sodium sulfate (DSS) and azoxymethane (AOM)-DSS experimental models, respectively. Muc4(-/-) mice were viable, fertile with no apparent defects. Muc4(-/-) mice displayed increased resistance to DSS-induced colitis compared with wild-type (WT) littermates that was evaluated by survival rate, body weight loss, diarrhea and fecal blood score, and histological score. Reduced infiltration of inflammatory cells, that is, CD3(+) lymphocytes and F4/80(+) macrophages was observed in the inflamed mucosa along with reduction in the mRNA levels of inflammatory cytokines interleukin (IL)-1β and tumor necrosis factor (TNF)-α and anti-microbial genes Lysozyme M and SLPI in the colon of Muc4(-/-) mice compared with WT littermates. Compensatory upregulation of Muc2 and Muc3 mucins under basal and DSS treatment conditions partly explains the resistance observed in Muc4(-/-) mice. Accordingly, Muc4(-/-) mice exhibited significantly reduced tumor burden compared with WT mice assessed in a colitis-induced tumor model using AOM/DSS. An increased percentage of Ki67(+) nuclei was observed in the tumors from WT compared with Muc4(-/-) mice suggesting Muc4 to be critical in intestinal cell proliferation during tumorigenesis. Taken together, we conclusively demonstrate for the first time the role of Muc4 in driving intestinal inflammation and inflammation-associated tumorigenesis using a novel Muc4(-/-) mouse model.

Chronic cigarette smoke exposure induces microbial and inflammatory shifts and mucin changes in the murine gut

Inflammatory bowel diseases (IBD) are complex multifactorial diseases characterized by an inappropriate host response to an altered commensal microbiome and dysfunctional mucus barrier. Cigarette smoking is the best known environmental risk factor in IBD. Here, we studied the influence of chronic smoke exposure on the gut microbiome, mucus layer composition and immune factors in conventional mice. We compared smoke-exposed with air-exposed mice (n = 12) after a smoke exposure of 24 weeks. Both Illumina sequencing (n = 6) and denaturing gradient gel electrophoresis (n = 12) showed that bacterial activity and community structure were significantly altered in the colon due to smoke exposure. Interestingly, an increase of Lachnospiraceae sp. activity in the colon was observed. Also, the mRNA expression of Muc2 and Muc3 increased in the ileum, whereas Muc4 increased in the distal colon of smoke-exposed mice (n = 6). Furthermore, we observed increased Cxcl2 and decreased Ifn-γ in the ileum, and increased Il-6 and decreased Tgf-β in the proximal colon. Tight junction gene expression remained unchanged. We infer that the modulating role of chronic smoke exposure as a latently present risk factor in the gut may be driven by the altered epithelial mucus profiles and changes in microbiome composition and immune factors.

The Goblet Cell Protein Clca1 (Alias mClca3 or Gob-5) Is Not Required for Intestinal Mucus Synthesis, Structure and Barrier Function in Naive or DSS-Challenged Mice

The secreted, goblet cell-derived protein Clca1 (chloride channel regulator, calcium-activated-1) has been linked to diseases with mucus overproduction, including asthma and cystic fibrosis. In the intestine Clca1 is found in the mucus with an abundance and expression pattern similar to Muc2, the major structural mucus component. We hypothesized that Clca1 is required for the synthesis, structure or barrier function of intestinal mucus and therefore compared wild type and Clca1-deficient mice under naive and at various time points of DSS (dextran sodium sulfate)-challenged conditions. The mucus phenotype in Clca1-deficient compared to wild type mice was systematically characterized by assessment of the mucus protein composition using proteomics, immunofluorescence and expression analysis of selected mucin genes on mRNA level. Mucus barrier integrity was assessed in-vivo by analysis of bacterial penetration into the mucus and translocation into sentinel organs combined analysis of the fecal microbiota and ex-vivo by assessment of mucus penetrability using beads. All of these assays revealed no relevant differences between wild type and Clca1-deficient mice under steady state or DSS-challenged conditions in mouse colon. Clca1 is not required for mucus synthesis, structure and barrier function in the murine colon.

Dietary intervention with serum-derived bovine immunoglobulins protects barrier function in a mouse model of colitis

Dietary supplementation with immunoglobulins from animal plasma has anti-inflammatory effects on intestinal and lung models of acute inflammation. Here, we aimed to establish whether dietary intervention with serum-derived bovine immunoglobulin (SBI) can prevent alterations in intestinal barrier function in a mouse model with a genetic predisposition to inflammatory bowel disease (IBD). Wild-type (WT) mice and mice lacking the mdr1a gene (KO) were fed diets supplemented with either SBI (2% wt/wt) or milk proteins (control diet), from day 21 (weaning) until day 56. The epithelial permeability of distal colon crypts was measured by confocal microscopy using a fluorescent marker. The expression of junctional epithelial E-cadherin and β-catenin proteins were determined by Western blot and zonula occludens-1 (ZO-1) by immunofluorescence. Mucins (MUC1, MUC2, MUC4), TFF3, cytokines (TNF-α, IFN-γ), and inducible nitric oxide synthase RNA expression were quantified by real-time PCR. SBI blocked the increase in colon crypt permeability and partially prevented the reduction in E-cadherin and ZO-1 expression that characterize the KO mouse model (both P < 0.05). SBI inclusion also reduced the mucosal expression of the inflammatory markers TNF-α, IFN-γ, and inducible nitric oxide synthase (all P < 0.005). The number of goblet cells in the colon of KO mice was low and correlated well with MUC2 and TFF3 expression (P < 0.001), whereas dietary supplementation with SBI attenuated these effects (all P < 0.05). In short, dietary SBI ameliorated colonic barrier alterations and reduced the expression of mucosal inflammatory markers in a genetic model of IBD.

Preventive and therapeutic effects of Lactobacillus paracasei B21060-based synbiotic treatment on gut inflammation and barrier integrity in colitic mice

BACKGROUND

Although gut microbiota perturbation is recognized as a main contributing factor to the pathogenesis of inflammatory bowel disease, synbiotic therapies, as prevention or treatment, have remained overlooked.

OBJECTIVE

To verify whether Lactobacillus paracasei B21060-based synbiotic therapy could prevent or repair colon damage in a mouse model of colitis, we performed treatments before and after colitis induction.

METHODS

The experimental study lasted 19 d. Experimental colitis was induced in BALB/c mice by giving them dextran sodium sulfate (DSS, 2.5%) in drinking water (days 7-12) followed by DSS-free water (days 13-19) (DSS group). L. paracasei B21060 (2.5 × 10(7) bacteria/10 g body weight) was orally administered 7 d before DSS [synbiotic as preventive treatment (P-SYN) group] or 2 d after DSS [synbiotic as therapeutic treatment (T-SYN) group] until day 19. Another group was not treated with DSS or synbiotic and was given tap water (control group), for a total of 4 groups.

RESULTS

Compared with the DSS group, both synbiotic-treated groups had significantly less pronounced weight loss and colon damage. Consistently, mRNA levels of chemokine (C-C motif) ligand 5 in the colon were reduced in both P-SYN and T-SYN mice compared with the DSS group (51%, P < 0.05 and 72%, P < 0.001, respectively). In the P-SYN and T-SYN groups, neutrophil elastase transcription was also reduced (51%, P < 0.01 and 59%, P < 0.001, respectively). Accordingly, oxidative/nitrosative stress was lower in P-SYN and T-SYN mice than in the DSS group. In P-SYN and T-SYN mice, colonic gene expression of tumor necrosis factor (47%, P < 0.01 and 61%, P < 0.001, respectively) and prostaglandin-endoperoxide synthase 2 (45%, P < 0.01 and 35%, P < 0.05, respectively) was lower, whereas interleukin 10 mRNA was doubled compared with the DSS group (both P < 0.5). Remarkably, epithelial barrier integrity (zonulin and occludin) and gut protection (β-defensin and mucin expression) were completely restored in P-SYN and T-SYN mice.

CONCLUSIONS

Our data highlight the beneficial effects of this synbiotic formulation in acutely colitic mice, suggesting that it may have therapeutic and possibly preventive efficacy in human colitis.

MUC1-C activates the TAK1 inflammatory pathway in colon cancer

The mucin 1 (MUC1) oncoprotein has been linked to the inflammatory response by promoting cytokine-mediated activation of the NF-κB pathway. The TGF-β-activated kinase 1 (TAK1) is an essential effector of proinflammatory NF-κB signaling that also regulates cancer cell survival. The present studies demonstrate that the MUC1-C transmembrane subunit induces TAK1 expression in colon cancer cells. MUC1 also induces TAK1 in a MUC1(+/-)/IL-10(-/-) mouse model of colitis and colon tumorigenesis. We show that MUC1-C promotes NF-κB-mediated activation of TAK1 transcription and, in a positive regulatory loop, MUC1-C contributes to TAK1-induced NF-κB signaling. In this way, MUC1-C binds directly to TAK1 and confers the association of TAK1 with TRAF6, which is necessary for TAK1-mediated activation of NF-κB. Targeting MUC1-C thus suppresses the TAK1NF-κB pathway, downregulates BCL-XL and in turn sensitizes colon cancer cells to MEK inhibition. Analysis of colon cancer databases further indicates that MUC1, TAK1 and TRAF6 are upregulated in tumors associated with decreased survival and that MUC1-C-induced gene expression patterns predict poor outcomes in patients. These results support a model in which MUC1-C-induced TAK1NF-κB signaling contributes to intestinal inflammation and colon cancer progression.

A soybean and fish oil mixture with different n-6/n-3 PUFA ratios modulates the inflammatory reaction in mice with dextran sulfate sodium-induced acute colitis

BACKGROUND & AIMS

Inflammatory bowel disease is a recurrent disease of the gastrointestinal tract. n-3 polyunsaturated fatty acids (PUFAs) are proved to have anti-inflammatory and immunomodulatory properties. This study evaluated the effects of different dietary n-6/n-3 PUFA ratios on the mechanism of alleviating the inflammatory response in mice with dextran sulfate sodium (DSS)-induced colitis.

METHODS

Mice were randomly assigned to 6 groups including 3 non-colitis groups (C, LF, and HF) and 3 colitis groups (DC, DLF, and DHF). Mice in the C and DC groups were fed a common semipurified diet with soybean oil as the fat source. The other groups received an identical component except that part of the soybean oil was replaced by different amounts of fish oil. The n-6/n-3 PUFA ratio of the LF and DLF groups was 4:1, the ratio of the HF and DHF groups was 2:1. After feeding the respective diets for 2 weeks, the colitis groups were given distilled water containing 2% DSS, while the non-colitis groups were given distilled water for 5 days. After that, all mice were sacrificed at the recovery phase after drinking distilled water for another 5 days.

RESULTS

Colitis resulted in higher expressions of colonic inflammatory mediators in colon tissues and colon lavage fluid. Also, colonic peroxisome proliferator-activated receptor (PPAR)-γ and the IκBα/nuclear factor (NF)-κB p65 ratio were lower than those of the non-colitis groups. Compared to the DC group, fish oil-enriched colitis groups had lower inflammatory mediator expressions and higher PPAR-γ protein levels and IκBα/NF-κB p65 ratios in colon tissues. The DHF group had even lower colonic inflammatory gene and higher PPAR-γ protein expressions than did the DLF group.

CONCLUSIONS

These findings suggest that diets enriched with fish oil upregulated PPAR-γ and decreased NF-κB activation that may consequently have reduced luminal inflammatory mediator production. Compared to a n-6/n-3 PUFA ratio 4:1, a ratio of 2:1 was more effective in reducing inflammatory reactions in DSS-induced colitis.

Effects of dietary glutamine on the homeostasis of CD4+ T cells in mice with dextran sulfate sodium-induced acute colitis

This study investigated the effects of dietary glutamine (Gln) on T-helper (Th) and T regulatory (Treg) cell homeostasis and colonic inflammatory mediator expression in mice with dextran sulfate sodium (DSS)-induced colitis. Mice were randomly assigned to 4 groups with 2 normal control (C and G) and 2 DSS-treated groups (DC and DG). The C and DC groups were fed a common semipurified diet, while the G and DG groups received an identical diet except that part of the casein was replaced by Gln, which provided 25% of the total amino acid nitrogen. Mice were fed the diets for 10 days. On day 6, mice in the normal control groups were given distilled water, while those in the DSS groups were given distilled water containing 1.5% DSS for 5 d. At the end of the experiment, the mice were sacrificed for further examination. Results showed that DC group had higher plasma haptoglobin, colonic weight, immunoglobulin G, inflammatory cytokine and nuclear factor (NF)-κB protein levels. Gln administration lowered inflammatory mediators and NF-κB/IκBα ratio in colitis. Compared with the DC group, the percentages of interleukin-17F and interferon-γ in blood and transcription factors, T-bet and RAR-related orphan receptor-γt, gene expressions in mesenteric lymph nodes were lower, whereas blood Foxp3 was higher in the DG group. Also, DG group had lower colon injury score. These results suggest that Gln administration suppressed Th1/Th17 and Th-associated cytokine expressions and upregulated the expression of Tregs, which may modulate the balance of Th/Treg and reduce inflammatory reactions in DSS-induced colitis.

MUC4 as a diagnostic marker in cancer

BACKGROUND

Mucins are high molecular mass glycoproteins whose role in diagnosis, prognosis and therapy is being increasingly recognized owing to their altered expression in a variety of carcinomas. MUC4, a membrane-bound mucin encoded by a gene located on chromosome locus 3q29, is aberrantly expressed in several cancers including those of the bile duct, breast, colon, esophagus, ovary, lung, prostate, stomach and pancreas.

OBJECTIVE

This review considers the potential use of the MUC4 expression pattern in the diagnosis and prognosis of various cancers.

RESULTS/CONCLUSION

MUC4 expression is a specific marker of epithelial tumors and its expression correlates positively with the degree of differentiation in several cancers. Importantly, MUC4 has emerged as a specific marker of dysplasia, being expressed in the earliest dysplastic lesions preceding several malignancies, including lethal pancreatic cancer. The presence of MUC4-specific antibodies in the serum and of the transcript in peripheral blood mononuclear cells of cancer patients raises the possibility of it emerging as a new diagnostic biomarker for bedside application in high-risk individuals and those with established cancer.

Dendritic cells administered intrarectally penetrate the intestinal barrier to break intestinal tolerance via Th2-medeiated colitis in mice

Intestinal lamina propria dendritic cells (LPDCs) in mice are known to extend dendrites between the intestinal epithelia and the luminal side when processing luminal antigens. We conducted intrarectal cell transfer experiments of bone marrow-derived dendritic cells (BMDCs) in mice to assess dendritic cell penetration of the intestine. Intrarectally administered GFP(+) BMDCs localized in the colonic LP within 3h and the spleen within 12h after administration. 72h after administration, recipient C57BL/6 mice showed acute diarrhea, and administration of BMDCs (once weekly for 3 weeks) induced intestinal inflammation with increased numbers of recipient macrophages and CD4(+) T cells exhibiting a Th2-mediated immune response. These results demonstrate that DCs actively communicate across the intestinal barrier, and highlight a potential technique for controlling colonic immune tolerance.

Urinary proteome analysis of irritable bowel syndrome (IBS) symptom subgroups

Irritable bowel syndrome (IBS) is a functional gastrointestinal (GI) disorder characterized by chronic abdominal pain associated with alterations in bowel function. Given the heterogeneity of the symptoms, multiple pathophysiologic factors are suspected to play a role. We classified women with IBS into four subgroups based on distinct symptom profiles. In-depth shotgun proteomic analysis was carried out to profile the urinary proteomes to identify possible proteins associated with these subgroups. First void urine samples with urine creatinine level≥100 mg/dL were used after excluding samples that tested positive for blood. Urine from 10 subjects representing each symptom subgroup was pooled for proteomic analysis. The urine proteome was analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) using a data-independent method known as Precursor Acquisition Independent From Ion Count (PAcIFIC) that allowed extended detectable dynamic range. Differences in protein quantities were determined by peptide spectral counting followed by validation of select proteins with ELISA or a targeted single reaction monitoring (LC-SRM/MS) approach. Four IBS symptom subgroups were selected: (1) Constipation, (2) Diarrhea+Low Pain, (3) Diarrhea+High Pain, and (4) High Pain+High Psychological Distress. A fifth group consisted of Healthy Control subjects. From comparisons of quantitative spectral counting data among the symptom subgroups and controls, a total of 18 proteins that showed quantitative differences in relative abundance and possible physiological relevance to IBS were selected for further investigation. Three of the 18 proteins were chosen for validation by either ELISA or SRM. An elevated expression of gelsolin (GSN) was associated with the high pain groups. Trefoil Factor 3 (TFF3) levels were higher in IBS groups compared to controls. In this study, the IBS patients subclassified by predominant symptoms showed differences in urine proteome levels. Proteins showing distinctive changes are involved in homeostasis of intestinal function and inflammatory response. These findings warrant future studies with larger, independent cohorts to enable more extensive assessment and validation of urinary protein markers as a diagnostic tool in adults with IBS.

Avaliação do número de células caliciformes nas criptas da mucosa colônica com e sem trânsito intestinal

OBJETIVO: Medir a espessura das criptas e quantificar o número de células caliciformes comparando a mucosa cólica com e sem trânsito intestinal, relacionando-as ao tempo de exclusão. MÉTODOS: Sessenta ratos Wistar, foram distribuídos em três grupos com 20 animais segundo a operação final para a retirada dos cólons, realizadas em seis, 12 ou 18 semanas. Em cada grupo, 15 animais foram submetidos à derivação do trânsito por colostomia proximal no cólon esquerdo e fístula mucosa distal e cinco apenas à laparotomia (controle). Os cólons com e sem trânsito fecal foram removidos, processados, submetidos a cortes histológicos corados pela hematoxilina-eosina. A altura das criptas colônicas e o número de células caliciformes foram mensurados por morfometria computadorizada. Foram utilizados os testes t de Student e Kruskal-Wallis para comparação e análise de variância, estabelecendo-se nível de significância de 5% (p<0,05). RESULTADOS: A altura das criptas diminui nos segmentos sem trânsito fecal (p=0,0001), reduzindo entre seis e 12 semanas de exclusão (p=0,0003), estabilizando-se após este período. O número de células caliciformes nas criptas é menor nos segmentos sem trânsito após 12 e 18 semanas (p=0,0001), porém aumenta com o decorrer do tempo de exclusão (p=0,04) CONCLUSÃO: A exclusão do trânsito intestinal diminui a espessura das criptas colônicas e o número de células caliciformes nos segmentos sem trânsito. Existe aumento do número de células caliciformes com o decorrer do tempo de exclusão.

MicroRNA-150 directly targets MUC4 and suppresses growth and malignant behavior of pancreatic cancer cells

Pancreatic cancer (PC) has the worst prognosis among all cancers due to its late diagnosis and lack of effective therapies. Therefore, identification of novel gene targets, which are differentially expressed in PC and functionally involved in malignant phenotypes, is critical to achieve early diagnosis and development of effective therapeutic strategies. We have shown previously that MUC4, an aberrantly overexpressed transmembrane mucin, promotes growth, invasion and metastasis of PC cells, thus underscoring its potential as a clinical target. Here, we report a novel microRNA (miRNA)-mediated mechanism underlying aberrant expression of MUC4 in PC. We demonstrate that the 3' untranslated region of MUC4 contains a highly conserved miRNA-150 (miR-150) binding motif and its direct interaction with miR-150 downregulates endogenous MUC4 protein levels. We also show that miR-150-mediated MUC4 downregulation is associated with a concomitant decrease in human epidermal growth factor receptor 2 and its phosphorylated form, leading to reduced activation of downstream signaling. Furthermore, our findings demonstrate that miR-150 overexpression inhibits growth, clonogenicity, migration and invasion and enhances intercellular adhesion in PC cells. Finally, our data reveal a downregulated expression of miR-150 in malignant pancreatic tissues, which is inversely associated with MUC4 protein levels. Altogether, these findings establish miR-150 as a novel regulator of MUC4 and a tumor suppressor miRNA in PC.

Soy protein diet, but not Lactobacillus rhamnosus GG, decreases mucin-1, trefoil factor-3, and tumor necrosis factor-α in colon of dextran sodium sulfate-treated C57BL/6 mice

The incidence of inflammatory bowel diseases has increased during recent decades. Within the colon, the families of mucins (MUC) and trefoil factors (TFF) facilitate mucosal protection. Probiotic administration influences the intestinal MUC layer. Additionally, food components may affect gut microflora or have direct effects on the MUC barrier. Our objective was to determine whether diet and/or Lactobacillus rhamnosus GG (LGG) would mediate dextran sodium sulfate (DSS)-induced colitis by altering expression of the MUC and TFF genes. C57BL/6 mice were fed diets containing 20% (wt:wt) casein, soy, or whey proteins with or without LGG for 12 d. Seven days after starting LGG diets, the mice were given 2% DSS in drinking water for 4 d. Two additional casein groups with or without LGG were given tap water, for a total of 8 groups. One day after the DSS treatment, the mice were killed and the colon and cecum tissues and cecum contents were collected and analyzed by qRT-PCR. Whey protein significantly increased cecal LGG content compared with the other diets. In the casein diet groups, MUC1 and TFF-3 expression in colon was significantly induced by DSS independent of LGG. Compared with other DSS-treated groups, soy protein decreased MUC-1 and TFF-3 in the colon. Similarly, soy protein decreased the impact of DSS on inflammatory scores, TNFα gene expression, and colon shortening. There was no overall effect of LGG on these measurements. In conclusion, soy protein suppressed the DSS-induced inflammatory stimulation of MUC, TFF, and TNFα gene expression independently of LGG.

Antibiotic treatment alters the colonic mucus layer and predisposes the host to exacerbated Citrobacter rodentium-induced colitis

Antibiotics are often used in the clinic to treat bacterial infections, but the effects of these drugs on microbiota composition and on intestinal immunity are poorly understood. Citrobacter rodentium was used as a model enteric pathogen to investigate the effect of microbial perturbation on intestinal barriers and susceptibility to colitis. Streptomycin and metronidazole were used to induce alterations in the composition of the microbiota prior to infection with C. rodentium. Metronidazole pretreatment increased susceptibility to C. rodentium-induced colitis over that of untreated and streptomycin-pretreated mice, 6 days postinfection. Both antibiotic treatments altered microbial composition, without affecting total numbers, but metronidazole treatment resulted in a more dramatic change, including a reduced population of Porphyromonadaceae and increased numbers of lactobacilli. Disruption of the microbiota with metronidazole, but not streptomycin treatment, resulted in an increased inflammatory tone of the intestine characterized by increased bacterial stimulation of the epithelium, altered goblet cell function, and thinning of the inner mucus layer, suggesting a weakened mucosal barrier. This reduction in mucus thickness correlates with increased attachment of C. rodentium to the intestinal epithelium, contributing to the exacerbated severity of C. rodentium-induced colitis in metronidazole-pretreated mice. These results suggest that antibiotic perturbation of the microbiota can disrupt intestinal homeostasis and the integrity of intestinal defenses, which protect against invading pathogens and intestinal inflammation.

Aberrant upregulation of MUC4 mucin expression in cutaneous condyloma acuminatum and squamous cell carcinoma suggests a potential role in the diagnosis and therapy of skin diseases

AIM

Mucins comprise a family of high-molecular-weight glycoproteins. MUC4, a large transmembrane mucin, has recently emerged as a novel marker for diagnosis, prognosis and therapy in several malignancies. However, its role in skin pathologies remains unknown. The aim of this study was to analyse the expression of MUC4 in cutaneous pathologies by immunohistochemistry for potential diagnostic, prognostic and therapeutic applications.

METHODS

A total of 330 tissue spots representing the normal skin, and benign and malignant cutaneous diseases, were analysed after staining with the monoclonal antibody to human MUC4 (clone 8G7).

RESULTS

While the normal epidermis showed a negative to weak-positive expression of MUC4, its expression was significantly upregulated in squamous cell carcinomas (SCCs) where the intensity of staining correlated negatively with tumour grade and positively with age. A moderately strong MUC4 expression was also noted in 2/20 cancer adjacent normal skin and 2/21 chronically inflamed skin tissues, while 10/19 cases of vulval condyloma acuminate, 3/12 of vulval hyperplasia and 2 cases of verruca vulgaris also showed strong MUC4 positivity. Malignant melanoma, basal cell carcinoma and cutaneous cysts were negative.

CONCLUSION

The results indicate that MUC4 expression is aberrantly upregulated in cutaneous SCCs, vulval condylomas and verruca vulgaris. Further, it appears that MUC4 expression in the skin may be modulated by chronic inflammation and the presence of an adjacent cutaneous malignancy in certain cases. These observations suggest a novel role for MUC4 mucin in the pathogenesis of cutaneous SCC and a possible application as a diagnostic and/or prognostic marker in cutaneous pathologies.

Phaseolin from Phaseolus vulgaris bean modulates gut mucin flow and gene expression in rats

Dietary protein might modulate mucin flow and intestinal mucin gene expression. Since unheated phaseolin from Phaseolus vulgaris bean is resistant to digestion and increases gut endogenous protein losses, we hypothesised that unheated phaseolin influences mucin flow and gene expression, and that phaseolin heat treatment reverses these effects. The hypothesis was tested using a control diet containing casein as the sole protein source and three other diets with casein being replaced by 33 and 67 % of unheated and 67 % of heated phaseolin. The rats were fed for 6 d and euthanised. Digesta and faeces were collected for determining digestibility and mucin flow. Gut tissues were collected for mucin (Muc1, Muc2, Muc3 and Muc4) and Trefoil factor 3 (Tff3) gene expressions. Colonic mucin flow decreased linearly with increasing the dietary level of unheated phaseolin (P < 0·05). Unheated phaseolin increased N flow in ileum, colon and faeces (P < 0·05), and reduced apparent N digestibility linearly (P < 0·01). Heat treatment reversed all these changes (P < 0·05 to < 0·001), except mucin flow. The expressions of Muc mRNA in gut tissues were influenced by dietary phaseolin level (ileum and colon: Muc3 and Muc4) and thermal treatment (ileum: Muc2; colon: Muc2, Muc3, Muc4 and Tff3) (P < 0·05 to 0·001). In conclusion, phaseolin modulates mucin flow and Muc gene expression along the intestines differentially.

Early-stage blocking of Notch signaling inhibits the depletion of goblet cells in dextran sodium sulfate-induced colitis in mice

BACKGROUND

Goblet cells, which contribute to mucosal defense and repair in the intestinal epithelium, are depleted in human and rodent colitis. The Notch signal pathway regulates the differentiation of intestinal stem cells into epithelial cells and inhibits the differentiation of secretory lineages, including goblet cells. The aim of our study was to clarify whether the blocking of the Notch pathway at an early stage of colitis would preserve goblet cells and facilitate the healing process in dextran sulfate sodium (DSS)-induced colitis in mice.

METHODS

DSS was orally administered to C57/BL6 mice for 7 days, and dibenzazepine (DBZ), a Notch pathway blocker, was administered for 5 consecutive days, beginning on the first day of DSS treatment. Colonic mucosal inflammation was evaluated clinically, biochemically, and histologically. The expression of the goblet cell-associated genes Math1 and MUC2 and proinflammatory cytokines was evaluated by real-time reverse-transcriptase-PCR, with the expression of Math1 and MUC2 also visualized by immunohistochemical examination.

RESULTS

The administration of DBZ at 4 mumol/kg significantly reduced the severity of the colitis. Compared with the DSS only-treated intestine, the number of goblet cells was relatively sustained, and the expression of Math1 and MUC2 was also elevated in the DSS/DBZ-treated intestine. DBZ treatment suppressed the mRNA levels for interleukin-1beta and -6, and matrix metalloproteinases-3 and -9 in the DSS-treated intestine.

CONCLUSIONS

Early-stage blocking of Notch signaling may ameliorate acute DSS colitis by preventing reduction in the number of goblet cells.

Muc2 protects against lethal infectious colitis by disassociating pathogenic and commensal bacteria from the colonic mucosa

Despite recent advances in our understanding of the pathogenesis of attaching and effacing (A/E) Escherichia coli infections, the mechanisms by which the host defends against these microbes are unclear. The goal of this study was to determine the role of goblet cell-derived Muc2, the major intestinal secretory mucin and primary component of the mucus layer, in host protection against A/E pathogens. To assess the role of Muc2 during A/E bacterial infections, we inoculated Muc2 deficient (Muc2^−/−) mice with Citrobacter rodentium, a murine A/E pathogen related to diarrheagenic A/E E. coli. Unlike wildtype (WT) mice, infected Muc2^−/− mice exhibited rapid weight loss and suffered up to 90% mortality. Stool plating demonstrated 10–100 fold greater C. rodentium burdens in Muc2^−/− vs. WT mice, most of which were found to be loosely adherent to the colonic mucosa. Histology of Muc2^−/− mice revealed ulceration in the colon amid focal bacterial microcolonies. Metabolic labeling of secreted mucins in the large intestine demonstrated that mucin secretion was markedly increased in WT mice during infection compared to uninfected controls, suggesting that the host uses increased mucin release to flush pathogens from the mucosal surface. Muc2 also impacted host-commensal interactions during infection, as FISH analysis revealed C. rodentium microcolonies contained numerous commensal microbes, which was not observed in WT mice. Orally administered FITC-Dextran and FISH staining showed significantly worsened intestinal barrier disruption in Muc2^−/− vs. WT mice, with overt pathogen and commensal translocation into the Muc2^−/− colonic mucosa. Interestingly, commensal depletion enhanced C. rodentium colonization of Muc2^−/− mice, although colonic pathology was not significantly altered. In conclusion, Muc2 production is critical for host protection during A/E bacterial infections, by limiting overall pathogen and commensal numbers associated with the colonic mucosal surface. Such actions limit tissue damage and translocation of pathogenic and commensal bacteria across the epithelium.

Enteropathogenic E. coli (EPEC) and Enterohemorrhagic E. coli (EHEC) are important causes of diarrheal disease and other serious complications worldwide. Despite many studies addressing the pathogenic strategies used by these microbes, how the host protects itself from these pathogens is poorly understood. A critical question we address here is whether the thick mucus layer that overlies the intestinal surface plays a role in host protection. Since EPEC and EHEC do not infect mice efficiently, we used a related mouse pathogen called Citrobacter rodentium to infect and compare responses between wildtype mice and Muc2-deficient mice, which are defective in mucus production. We show that Muc2-deficient mice are extremely susceptible to C. rodentium infection-induced mortality and disease. Muc2-deficient mice were also colonized faster and had higher pathogen burdens throughout the experiment. Resident (non-pathogenic) bacteria were found to interact with C. rodentium and host tissues in Muc2-deficient mice, indicating Muc2 regulates all forms of intestinal microbiota at the gut surface. Deficiency in mucus production also contributed to increased leakiness of the gut, which allowed microbes to enter mucosal tissues. Our study shows that Muc2-dependent mucus production is critical for effective management of both pathogenic and non-pathogenic bacteria during infection by an EPEC/EHEC-like pathogen.

Effect of pro-inflammatory mediators on membrane-associated mucins expressed by human ocular surface epithelial cells

Membrane-associated mucins are altered on the ocular surface in non-Sjögren's dry eye. This study sought to determine if inflammatory mediators, present in tears of dry eye patients, regulate membrane-associated mucins MUC1 and -16 at the level of gene expression, protein biosynthesis and/or ectodomain release. A human corneal limbal epithelial cell line (HCLE), which produces membrane-associated mucins, was used. Cells were treated with interleukin (IL)-6, -8, or -17, tumor necrosis factor-alpha (TNF-alpha), and Interferon-gamma (IFN-gamma), or a combination of TNF-alpha and IFN-gamma, or IFN-gamma and IL-17, for 1, 6, 24, or 48 h. Presence of receptors for these mediators was verified by RT-PCR. Effects of the cytokines on expression levels of MUC1 and -16 were determined by real-time PCR, and on mucin protein biosynthesis and ectodomain release in cell lysates and culture media, respectively, by immunoblot analysis. TNF-alpha and IFN-gamma each significantly induced MUC1 expression, cellular protein content and ectodomain release over time. Combined treatment with the two cytokines was not additive. By comparison, one of the inflammatory mediators, IFN-gamma, affected all three parameters-gene expression, cellular protein, and ectodomain release-for MUC16. Combined treatment with TNF-alpha and IFN-gamma showed effects similar to IFN-gamma alone, except that ectodomain release followed that of TNF-alpha, which induced MUC16 ectodomain release. In conclusion, inflammatory mediators present in tears of dry eye patients can affect MUC1 and -16 on corneal epithelial cells and may be responsible for alterations of surface mucins in dry eye.

CaM kinase II in colonic smooth muscle contributes to dysmotility in murine DSS-colitis

BACKGROUND

Altered calcium mobilization has been implicated in the development of colonic dysmotility in inflammatory bowel disease. The aim of this study was to investigate the mechanisms by which disrupted intracellular Ca(2+) signalling contributes to the impaired contractility of colon circular smooth muscles.

METHODS

Acute colitis was induced in C57Bl/6 mice with dextran sulphate sodium (DSS) in the drinking water for 5 days.

KEY RESULTS

Spontaneous and acetylcholine-evoked contractions, caffeine-evoked hyperpolarization, and SERCA2 and phospholamban expression were reduced compared with controls. Tetrodotoxin did not restore control levels of contractile activity. The amplitudes, but not the frequency, of intracellular Ca(2+) waves were increased compared with controls. Caffeine abolished intracellular Ca(2+) waves in control smooth muscle cells, but not in smooth muscle cells from DSS-treated mice. CaM kinase II activity and cytosolic levels of HDAC4 were increased, and I kappaB alpha levels were decreased in distal colon smooth muscles from DSS-treated mice.

CONCLUSIONS & INFERENCES

These results suggest that disruptions in intracellular Ca(2+) mobilization due to down-regulation of SERCA2 and phospholamban expression lead to increased CaM kinase II activity and cytosolic HDAC4 that may contribute to the dysmotility of colonic smooth muscles in colitis by enhancing NF-kappaB activity.

Effects of galacto-oligosaccharide ingestion on the mucosa-associated mucins and sucrase activity in the small intestine of mice

BACKGROUND

Galacto-oligosaccharides (GOS) are non-digestible oligosaccharides with short galactosyl chain units produced by lactose fermentation which are considered as prebiotics. Only few studies have investigated the effects of GOS medium-term ingestion on the small intestinal epithelium characteristics.

AIM OF THE STUDY

In this study, we evaluated the consequences of GOS ingestion on small intestinal mucosal morphology, on brush-border membrane enzyme activities and on mucin content in BALB/c mice.

METHODS

Mice received the experimental diets for 4 weeks and then the small intestine was collected to measure sucrase, lactase and alkaline phosphatase activities, to study the villus heights in the jejunum mucosa and to determine mucosal mucin content as well as MUC-2 and MUC-4 mRNAs expression by qRT-PCR.

RESULTS

Our results showed that GOS has no detectable effect on the intestine villus height but increased the total protein content by twofold. Sucrase activity was significantly increased in the intestinal mucosa recovered from animals fed the GOS diet without any detectable modification of lactase and phosphatase activities. Interestingly, GOS was also able to increase sucrase activity in cultured Caco-2 cells raising the view that they likely act directly on these cells. Furthermore, GOS was found to markedly increase O-linked glycoproteins associated with the intestinal mucosa without modifying MUC-2, MUC-4 mRNAs expression. Lastly, TNF-alpha mRNA expression was also not modified after GOS ingestion.

CONCLUSIONS

These results suggest that, in BALB/c mice, 4-week GOS ingestion is able to increase the small intestinal mucosa-associated mucin content and enterocyte-associated sucrase activity without modifying villus height.

Glucocorticoid availability in colonic inflammation of rat

Recent in vitro studies have shown the involvement of pro-inflammatory cytokines in the regulation of the local metabolism of glucocorticoids via 11beta-hydroxysteroid dehydrogenase type 1 and type 2 (11HSD1 and 11HSD2). However, direct in vivo evidence for a relationship among the local metabolism of glucocorticoids, inflammation and steroid enzymes is still lacking. We have therefore examined the changes in the local metabolism of glucocorticoids during colonic inflammation induced by TNBS and the consequences of corticosterone metabolism inhibition by carbenoxolone on 11HSD1, 11HSD2, cyclooxygenase 2 (COX-2), mucin 2 (MUC-2), tumor necrosis factor alpha (TNF-alpha), and interleukin 1beta (IL-1beta). The metabolism of glucocorticoids was measured in tissue slices in vitro and their 11HSD1, 11HSD2, COX-2, MUC-2, TNF-alpha, and IL-1beta mRNA abundances by quantitative reverse transcription-polymerase chain reaction. Colitis produced an up-regulation of colonic 11HSD1 and down-regulation of 11HSD2 in a dose-dependent manner, and these changes resulted in a decreased capacity of the inflamed tissue to inactivate tissue corticosterone. Similarly, 11HSD1 transcript was increased in colonic intraepithelial lymphocytes of TNBS-treated rats. Topical intracolonic application of carbenoxolone stimulated 11HSD1 mRNA and partially inhibited 11HSD2 mRNA and tissue corticosterone inactivation and these changes were blocked by RU-486. The administration of budesonide mimicked the effect of carbenoxolone. In contrast to the local metabolism of glucocorticoids, carbenoxolone neither potentiates nor diminishes gene expression for COX-2, TNF-alpha, and IL-1beta, despite the fact that budesonide down-regulated all of them. These data indicate that inflammation is associated with the down-regulation of tissue glucocorticoid catabolism. However, these changes in the local metabolism of glucocorticoids do not modulate the expression of COX-2, TNF-alpha, and IL-1beta in inflamed tissue.