Colonic Mucus Research Articles

Zinc Deficiency Does Not Correlate With Goblet Cell Depletion at Time of Fecal Transplant for Clostridium difficile Infection

Introduction:Clostridium difficile infections (CDI) are characterized by a colon mucus barrier defect facilitating C. difficile adherence and toxin delivery. Zinc deficiency has been associated with recurrence of CDI after fecal microbiota transplant (FMT), but the underlying mechanism is unknown. In mice, zinc deficiency associates with jejunal goblet cell (GC) depletion that reverses with zinc repletion. We hypothesize that zinc deficiency predisposes patients to FMT failure by inhibiting the restoration of a healthy mucus barrier following recurrent CDI (rCDI). We aim to investigate whether zinc deficiency is associated with crypt or surface epithelium GC depletion at time of FMT for rCDI. Methods: We performed a retrospective cohort study of 45 patients (mean age, 65; 36 women) undergoing colon biopsies at time of FMT for rCDI from 9/2013 - 9/2016 at a tertiary care center who had serum zinc measured <30 days before FMT; 30 subjects had a normal level and 15 subjects had a low level (< 0.66 μg/mL). Hematoxylin-eosin-stained histologic slides from formalin-fixed biopsy specimens were reviewed with light microscopy. Primary outcomes were colon crypt epithelium GC density (cells/crypt) and colon surface epithelium GC density (cells/mm). Secondarily, the impact of zinc supplementation in patients with deficiency was analyzed. Results: Zinc deficiency was not associated with reduced crypt GC density: normal zinc subjects had 64+25 GC/crypt (mean+SD) while low zinc subjects had 75+32 GC/crypt (P=0.349, Mann-Whitney U [U]). Likewise, surface GC density did not vary by zinc status: normal zinc subjects had 49+23 GC/mm while low zinc subjects had 53+37 GC/mm (P=0.959, U). Among low zinc subjects, 8/15 received zinc supplements prior to biopsy. Receipt of zinc supplements was not associated with increased crypt GC density (77+41 GC/crypt Supplemented vs. 72+19 GC/crypt Not Supplemented, P=0.855, U) or increased surface GC density (41+19 GC/mm Supplemented vs. 68+48 GC/mm Not Supplemented, P=0.203, U). Conclusion: Zinc deficiency was not associated with depletion of colon crypt or surface epithelium GC. Among low zinc patients, receipt of zinc supplements was not associated with increased GC density. Low serum zinc may reflect both zinc depletion and underlying inflammatory response, and a relationship between zinc and colon mucus production cannot be excluded. Further studies are required to identify whether zinc deficiency contributes mechanistically to FMT failure.

A Two-Component System Regulates Bacteroides fragilis Toxin to Maintain Intestinal Homeostasis and Prevent Lethal Disease

Intestinal microbes are recognized for their role in human disease. Enterotoxigenic Bacteroides fragilis (ETBF) has been implicated in inflammatory bowel disease and colorectal cancer; however, colonization alone is insufficient to cause these illnesses. We hypothesized that homeostasis in healthy carriers is maintained by colonic mucus, the major constituent of which is the glycoprotein Muc2. We found that Muc2-deficient mice succumb to lethal disease from ETBF colonization in a B.fragilis toxin (BFT)-dependent manner. We identify a toxin regulator, the two-component system RprXY, which suppresses BFT expression invitro and invivo. Overexpression of either component was sufficient to prevent lethal disease in Muc2-deficient mice. Our studies demonstrate that homeostasis in the context of ETBF colonization is dependent on a dynamic interaction between intestinal mucus, a bacterial toxin, and a toxin regulatory system. Regulation of virulence may offer a therapeutic target to maintain intestinal homeostasis in susceptible patients.

The effect of age on the intestinal mucus thickness, microbiota composition and immunity in relation to sex in mice.

A mucus layer covers and protects the intestinal epithelial cells from direct contact with microbes. This mucus layer not only prevents inflammation but also plays an essential role in microbiota colonization, indicating the complex interplay between mucus composition-microbiota and intestinal health. However, it is unknown whether the mucus layer is influenced by age or sex and whether this contributes to reported differences in intestinal diseases in males and females or with ageing. Therefore, in this study we investigated the effect of age on mucus thickness, intestinal microbiota composition and immune composition in relation to sex. The ageing induced shrinkage of the colonic mucus layer was associated with bacterial penetration and direct contact of bacteria with the epithelium in both sexes. Additionally, several genes involved in the biosynthesis of mucus were downregulated in old mice, especially in males, and this was accompanied by a decrease in abundances of various Lactobacillus species and unclassified Clostridiales type IV and XIV and increase in abundance of the potential pathobiont Bacteroides vulgatus. The changes in mucus and microbiota in old mice were associated with enhanced activation of the immune system as illustrated by a higher percentage of effector T cells in old mice. Our data contribute to a better understanding of the interplay between mucus-microbiota-and immune responses and ultimately may lead to more tailored design of strategies to modulate mucus production in targeted groups.

Emerging oral targeted therapies in inflammatory bowel diseases: opportunities and challenges.

To improve quality of life and prevent long-term risks in patients with inflammatory bowel diseases (IBDs: Crohn's disease, ulcerative colitis), it is essential to suppress inflammatory activity adequately. However, corticosteroids are only suitable for therapy of acute flares and the evidence for positive effects of immunosuppressive substances like azathioprine or 6-mercapropurine is mainly limited to maintenance of remission. In addition, only subgroups of patients benefit from biologicals targeting tumour necrosis factor α or α4β7 integrins. In summary, until now the disease activity is not sufficiently controlled in a relevant fraction of the patients with IBD. Thus, there is an urge for the development of new substances in the therapy of ulcerative colitis and Crohn's disease. Fortunately, new oral and parenteral substances are in the pipeline. This review will focus on oral substances, which have already passed phase II studies successfully at this stage. In this article, we summarize data regarding AJM300, phosphatidylcholine (LT-02), mongersen, ozanimod, filgotinib and tofacitinib. AJM300 and ozanimod were tested in patients with ulcerative colitis and target lymphocyte trafficking through inhibition of the α subunit of integrin, respectively binding to the sphingosine-1-phosphate receptor (subtypes 1 and 5) on lymphocytes. Mongersen was utilized in patients with Crohn's disease and accelerates the degradation of SMAD7 mRNA, which consequently strengthens the mainly anti-inflammatory signalling pathway of transforming growth factor β1. Various Janus kinase (JAK) inhibitors were developed, which inhibit the intracellular signalling pathway of cytokines. For example, the JAK1 blocker filgotinib was tested in Crohn's disease, whereas the JAK1/3 inhibitor tofacitinib was tested in clinical trials for both Crohn's disease and ulcerative colitis. A different therapeutic approach is the substitution of phosphatidylcholine (LT-02), which might recover the colonic mucus. Taken together, clinical trials with these new agents have opened avenues for further clinical studies and it can be expected that at least some of these agents will be finally approved for clinical therapy.

Comparative Genomic Analysis of the Human Gut Microbiome Reveals a Broad Distribution of Metabolic Pathways for the Degradation of Host-Synthetized Mucin Glycans and Utilization of Mucin-Derived Monosaccharides.

The colonic mucus layer is a dynamic and complex structure formed by secreted and transmembrane mucins, which are high-molecular-weight and heavily glycosylated proteins. Colonic mucus consists of a loose outer layer and a dense epithelium-attached layer. The outer layer is inhabited by various representatives of the human gut microbiota (HGM). Glycans of the colonic mucus can be used by the HGM as a source of carbon and energy when dietary fibers are not sufficiently available. Both commensals and pathogens can utilize mucin glycans. Commensals are mostly involved in the cleavage of glycans, while pathogens mostly utilize monosaccharides released by commensals. This HGM-derived degradation of the mucus layer increases pathogen susceptibility and causes many other health disorders. Here, we analyzed 397 individual HGM genomes to identify pathways for the cleavage of host-synthetized mucin glycans to monosaccharides as well as for the catabolism of the derived monosaccharides. Our key results are as follows: (i) Genes for the cleavage of mucin glycans were found in 86% of the analyzed genomes, which significantly higher than a previous estimation. (ii) Genes for the catabolism of derived monosaccharides were found in 89% of the analyzed genomes. (iii) Comparative genomic analysis identified four alternative forms of the monosaccharide-catabolizing enzymes and four alternative forms of monosaccharide transporters. (iv) Eighty-five percent of the analyzed genomes may be involved in potential feeding pathways for the monosaccharides derived from cleaved mucin glycans. (v) The analyzed genomes demonstrated different abilities to degrade known mucin glycans. Generally, the ability to degrade at least one type of mucin glycan was predicted for 81% of the analyzed genomes. (vi) Eighty-two percent of the analyzed genomes can form mutualistic pairs that are able to degrade mucin glycans and are not degradable by any of the paired organisms alone. Taken together, these findings provide further insight into the inter-microbial communications of the HGM as well as into host-HGM interactions.

Mucus organisation is shaped by colonic content; a new view

The colonic mucus barrier is commonly described as a continuous double layer covering the epithelium, separating the microbiota from the intestinal tissue. This model is currently considered valid throughout the colon. The colon is characterised by regional anatomo-functional specificities such as presence and consistency of contents and location. In this study, we characterised the organisation of the colonic mucus barrier in proximal and distal colon of rodents by histological and FISH staining, taking into account aforementioned specificities. By using longitudinal sections and imaging extensive areas of tissue with and without colonic contents, we have obtained a spatiotemporal overview of mucus organisation in the colon. We describe for the first time that the colonic mucus layer covers the faeces instead of the epithelium in the distal colon. This faecal mucus layer confines the microbiota to the faeces and prevents it from remaining in empty distal colon. In the proximal colon, the mucus did not form a separating layer between bacteria and epithelium. We conclude that the organisation of colonic mucus is reliant on the presence of the colonic content, and the location within the colon. Our findings reopen the discussion on the nature of the colonic mucus barrier.

Bacteria Tell Us How to Protect Our Intestine

The inner colon mucus layer capacity to separate bacteria from the epithelium is dependent on bacterial colonizers signaling to the host epithelium. In this issue of Cell Host & Microbe, Wlodarska etal. (2017) demonstrate that the mucin-utilizing Peptostreptococcus russellii protects the host from inflammatory disease via metabolite signals.

Rice Bran and Probiotics Alter the Porcine Large Intestine and Serum Metabolomes for Protection against Human Rotavirus Diarrhea.

Human rotavirus (HRV) is a leading cause of severe childhood diarrhea, and there is limited vaccine efficacy in the developing world. Neonatal gnotobiotic pigs consuming a prophylactic synbiotic combination of probiotics and rice bran (Pro+RB) did not exhibit HRV diarrhea after challenge. Multiple immune, gut barrier protective, and anti-diarrheal mechanisms contributed to the prophylactic efficacy of Pro+RB when compared to probiotics (Pro) alone. In order to understand the molecular signature associated with diarrheal protection by Pro+RB, a global non-targeted metabolomics approach was applied to investigate the large intestinal contents and serum of neonatal gnotobiotic pigs. The ultra-high performance liquid chromatography-tandem mass spectrometry platform revealed significantly different metabolites (293 in LIC and 84 in serum) in the pigs fed Pro+RB compared to Pro, and many of these metabolites were lipids and amino acid/peptides. Lipid metabolites included 2-oleoylglycerol (increased 293.40-fold in LIC of Pro+RB, p = 3.04E-10), which can modulate gastric emptying, andhyodeoxycholate (decreased 0.054-fold in the LIC of Pro+RB, p = 0.0040) that can increase colonic mucus production to improve intestinal barrier function. Amino acid metabolites included cysteine (decreased 0.40-fold in LIC, p = 0.033, and 0.62-fold in serum, p = 0.014 of Pro+RB), which has been found to reduce inflammation, lower oxidative stress and modulate mucosal immunity, and histamine (decreased 0.18-fold in LIC, p = 0.00030, of Pro+RB and 1.57-fold in serum, p = 0.043), which modulates local and systemic inflammatory responses as well as influences the enteric nervous system. Alterations to entire LIC and serum metabolic pathways further contributed to the anti-diarrheal and anti-viral activities of Pro+RB such as sphingolipid, mono/diacylglycerol, fatty acid, secondary bile acid, and polyamine metabolism. Sphingolipid and long chain fatty acid profiles influenced the ability of HRV to both infect and replicate within cells, suggesting that Pro+RB created a protective lipid profile that interferes with HRV activity. Polyamines act on enterocyte calcium-sensing receptors to modulate intracellular calcium levels, and may directly interfere with rotavirus replication. These results support that multiple host and probiotic metabolic networks, notably those involving lipid and amino acid/peptide metabolism, are important mechanisms through which Pro+RB protected against HRV diarrhea in neonatal gnotobiotic pigs.

Su1510 - Colonic Load Differentiates Organization of Mucus in Colon of Mouse and Rat; a Remodelling

Su1510 - Colonic Load Differentiates Organization of Mucus in Colon of Mouse and Rat; a Remodelling

Tu1905 - Gram-Positive Bacteria are held at a Distance in the Colon Mucus by the Lectin-Like Protein Zg16

Tu1905 - Gram-Positive Bacteria are held at a Distance in the Colon Mucus by the Lectin-Like Protein Zg16

Loss of Sprouty2 in the colonic epithelium limits inflammatory cytokine production and enhances Muc2 and Lgr5 expression during colitis

OBJECTIVESprouty2 (Spry2) is an intracellular modulator of MAPK signaling. Its expression is suppressed by tumor necrosis factor (TNF) in airway epithelium, but its regulation and activity in the intestinal tract are unknown. Aberrant MAPK signaling is associated with increased inflammatory cytokine production in diseases including inflammatory bowel disease, raising the possibility that Spry2 may play a role in regulating cytokine expression in the colon. MAPK is also an important regulator of secretory cell differentiation in the intestine. Here we tested the hypothesis that Spry2 regulation of MAPK signaling during colitis controls inflammatory cytokine production and goblet cell function, and thus impacts intestinal response to injury.METHODSWe generated VillinCre;Spry2FLOXXED mice that lack Spry2 in the intestinal epithelium (Spry2KOIE) and LysMCre;Spry2FLOXXED mice that lack Spry2 in cells of myeloid lineage. Mice were given 3% dextran sodium sulfate (DSS) in drinking water for 4 days followed by 3 days without DSS and colitis severity was assessed. Cytokine levels were determined by qPCR. Epithelial crypt cultures (colonoids) were generated to assess regulation of ISC and cell lineages. The role of MAPK signaling was tested with MEK inhibitor U0126.RESULTSDSS colitis caused a 59% reduction of colonic Spry2 (p&lt;0.05). Spry2KOIE mice subjected to DSS had decreased levels of TNF, CXCL2, IL1β, and IFNγ versus wildtype littermates, and were protected from histological damage (injury score reduced by 30%, p=0.037), weight loss, and colon shortening. In contrast, mice with Spry2 deletion in myeloid cells developed acute colitis similar to controls, suggesting an epithelial specific effect of Spry2 in colitis. Spry2KOIE mice showed higher colonic Lgr5 (ISC marker) and Muc2 (goblet cell marker) levels. In vitro, Spry2KOIE‐derived colonoids also showed a 3‐fold increase (p=0.005) in Muc2 expression and elevated Lgr5 expression. Because goblet cell differentiation is thought to be dependent upon MAPK signaling, we analyzed colonoids treated with the MAPK inhibitor, U0126, but surprisingly did not see reversal of the elevated Muc2 in Spry2KOIE colonoids.CONCLUSIONOur work demonstrates that Spry2 is robustly expressed in the colonic epithelium, and expression is regulated by injury and inflammation. This may represent a protective mechanism against tissue injury by limiting inflammatory cytokine production, thus supporting Lgr5+ ISCs and inducing expression of the protective mucin, Muc2. Elevated Muc2 in Spry2KOIE colonoids was independent of MAPK activation, suggesting loss of Spry2 may elicit colonic protection through an alternative route of inhibiting inflammatory cytokine production.Support or Funding InformationNIH R01DK095004 (MRF)

Tu1902 - The Protein Composition of the Human Colonic Mucus: Reduced Levels of Core Structural Components in Ulcerative Colitis

Tu1902 - The Protein Composition of the Human Colonic Mucus: Reduced Levels of Core Structural Components in Ulcerative Colitis

Tu1904 - Cross-Linking of the MUC2 Mucin by Isopeptide Bonds Stabilizes the Colon Mucus and is Altered in Patients with Ulcerative Colitis

Tu1904 - Cross-Linking of the MUC2 Mucin by Isopeptide Bonds Stabilizes the Colon Mucus and is Altered in Patients with Ulcerative Colitis

Giardia duodenalis Alters Intestinal Mucin Transcription and Disrupts the Mucus Layer in a Cysteine Protease‐dependent Manner

ObjectiveGiardia duodenalis is a diarrheagenic protozoan parasite that infects humans and animals across the world. Giardiasis is responsible for both acute and chronic illnesses, including post‐infectious irritable bowel syndrome (PI‐IBS) and extra‐intestinal complications. The mechanisms by which these occur remain unclear. Gastrointestinal mucus is mostly composed of MUC5AC mucin in the stomach and MUC2 in the intestine. We hypothesized that Giardia was able to overcome the protective functions of mucus to facilitate the onset and propagation of disease. Our aim was to assess whether and how Giardia proteases may impair the protective function of mucus.MethodsMuc2−/− (KO‐inf) and C57BL/6 (WT‐inf) mice were gavaged with Giardia trophozoites. Seven days post‐infection, tissues were collected for histology, qPCR, and analysis of bacterial translocation. Human colonic biopsies from healthy donors were exposed to Giardia trophozoites, and amounts of intracellular mucins were quantified. In vitro, Giardia trophozoites were incubated with a human mucus‐producing cell line, LS174T, to assess intracellular mucin content and MUC2 transcription. Trophozoites were incubated with or without E64 inhibitor to assess the role of its cysteine proteases. Lastly, Giardia's secreted products were incubated with purified human MUC2 to assess proteolysis via western blot.ResultsKO‐inf mice had a higher parasitic load compared to WT‐inf mice and lost weight over the period of infection. Compared to non‐infected mice, WT‐inf mice exhibited novel transcription of Muc5ac and decreased transcription of Muc2 in the jejunum. Both Muc2 and Muc5ac mRNA were increased in the colon. Muc5ac transcription was not induced in KO‐inf mice. WT‐inf mice had larger colonic mucus granules but a thinner mucus layer as demonstrated by staining with periodic‐acid Schiff/Alcian blue, wheat germ agglutinin, and fluorescent in situ hybridization for the location of commensal bacteria. Infected mice had bacterial translocation into the liver and spleen. Giardia spent media degraded human MUC2 in vitro. This was attenuated by E64. Human colonic biopsies exposed to Giardia had less intracellular mucin content. Giardia reduced intracellular mucin content in LS174T cells after 20, 40, and 60 minutes post‐infection, whereas it increased mucin content by 3 hours post‐infection. These effects were cysteine protease‐dependent and involved cellular protein kinase C. In vitro, Giardia increased MUC2 transcription after 1 hour post‐infection in a cysteine protease‐dependent manner.ConclusionsMuc2 protects against Giardia accumulation and induced weight loss. Giardia disrupts this mucosal protective barrier by direct proteolysis of the mucus layer and by altering mucin gene transcription‐specifically an increase of Muc5ac and Muc2 in the colon, and a decrease of Muc2 in the jejunum. The resultant loss of the mucus barrier was associated with increased bacterial translocation. Giardia‐induced alterations in mucin transcription, in addition to mucin degradation and depletion, were attenuated by a cysteine protease inhibitor, indicating a potential target to reduce Giardia‐induced pathology. Future research is needed to determine how these effects may contribute to acute and chronic disease.Support or Funding InformationHost‐Parasite Interactions NSERC CREATE and the Canadian Association of Gastroenterology

Brachyspira hyodysenteriae Infection Regulates Mucin Glycosylation Synthesis Inducing an Increased Expression of Core-2 O-Glycans in Porcine Colon.

Brachyspira hyodysenteriae causes swine dysentery (SD), leading to global financial losses to the pig industry. Infection with this pathogen results in an increase in B. hyodysenteriae binding sites on mucins, along with increased colonic mucin secretion. We predict that B. hyodysenteriae modifies the glycosylation pattern of the porcine intestinal mucus layer to optimize its host niche. We characterized the swine colonic mucin O-glycome and identified the differences in glycosylation between B. hyodysenteriae-infected and noninfected pigs. O-Glycans were chemically released from soluble and insoluble mucins isolated from five infected and five healthy colon tissues and analyzed using porous graphitized carbon liquid chromatography tandem mass spectrometry. In total, 94 O-glycans were identified, with healthy pigs having higher interindividual variation, although a larger array of glycan structures was present in infected pigs. This implied that infection induced loss of individual variation and that specific infection-related glycans were induced. The dominating structures shifted from core-4-type O-glycans in noninfected pigs toward core-2-type O-glycans in infected animals, which correlated with increased levels of the C2GnT glycosyl transferase. Overall, glycan chains from infected pigs were shorter and had a higher abundance of structures that were neutral or predominantly contained NeuGc instead of NeuAc, whereas they had a lower abundance of structures that were fucosylated, acidic, or sulfated than those from noninfected pigs. Therefore, we conclude that B. hyodysenteriae plays a major role in regulating colonic mucin glycosylation in pigs during SD. The changes in mucin O-glycosylation thus resulted in a glycan fingerprint in porcine colonic mucus that may provide increased exposure of epitopes important for host-pathogen interactions. The results from this study provide potential therapeutic targets and a platform for investigations of B. hyodysenteriae interactions with the host via mucin glycans.

MUC2 Mucin and Butyrate Contribute to the Synthesis of the Antimicrobial Peptide Cathelicidin in Response to Entamoeba histolytica- and Dextran Sodium Sulfate-Induced Colitis.

Embedded in the colonic mucus are cathelicidins, small cationic peptides secreted by colonic epithelial cells. Humans and mice have one cathelicidin-related antimicrobial peptide (CRAMP) each, LL-37/hCAP-18 and Cramp, respectively, with related structure and functions. Altered production of MUC2 mucin and antimicrobial peptides is characteristic of intestinal amebiasis. The interactions between MUC2 mucin and cathelicidins in conferring innate immunity against Entamoeba histolytica are not well characterized. In this study, we quantified whether MUC2 expression and release could regulate the expression and secretion of cathelicidin LL-37 in colonic epithelial cells and in the colon. The synthesis of LL-37 was enhanced with butyrate (a product of bacterial fermentation) and interleukin-1β (IL-1β) (a proinflammatory cytokine in colitis) in the presence of exogenously added purified MUC2. The LL-37 responses to butyrate and IL-1β were higher in high-MUC2-producing cells than in lentivirus short hairpin RNA (shRNA) MUC2-silenced cells. Activation of cyclic adenylyl cyclase (AMP) and mitogen-activated protein kinase (MAPK) signaling pathways was necessary for the simultaneous expression of MUC2 and cathelicidins. In Muc2 mucin-deficient (Muc2-/-) mice, murine cathelicidin (Cramp) was significantly reduced compared to that in Muc2+/- and Muc2+/+ littermates. E. histolytica-induced acute inflammation in colonic loops stimulated high levels of cathelicidin in Muc2+/+ but not in Muc2-/- littermates. In dextran sodium sulfate (DSS)-induced colitis in Muc2+/+ mice, which depletes the mucus barrier and goblet cell mucin, Cramp expression was significantly enhanced during restitution. These studies demonstrate regulatory mechanisms between MUC2 and cathelicidins in the colonic mucosa where an intact mucus barrier is essential for expression and secretion of cathelicidins in response to E. histolytica- and DSS-induced colitis.

Establishment and effect observation on three kinds of Ti-Xu with constipation rat models

To establish three types constipation models with the syndrome of Xue-Xu, Yin-Xu and Yang-Xu in rats, and to compare the difference of colonic motility, colonic water metabolism, colonic mucus secretion and the level of aquaporin-2 (AQP2). Forty Sprague Dawley rats, male and female in half, were randomly divided into four groups:normal control group(N), Xue-Xu with constipation group(XC), Yin-Xu with constipation group(YC) and Yang-Xu with constipation group(YAC). Bloodletting and loperamide were used to induce the Xue-Xu with constipation in rats, thyroxin and loperamide were used to induce the Yin-Xu with constipation in rats, ice-water stimulation and loperamide were used to induce the Yang-Xu with constipation in rats. Bloodletting was coducted once a week,drug was ad-ministrated orally to rats once a day for continuous 42 days. Rats'state, body weights, stool character, transfer time between mouth and anal, small intestinal propulsion rate were measured. The colon tissues of rats were stained with alcian blue-periodic acid schiff (AB-PAS) to analyze the changes of mucus secretion. The aquaporin-2 expressions in proximal and distal colon of rats were measured by immunohistochemical method. Compared to normal control group, weight-increasing speed of the rats were reduced in three models. The order of indepen-dent movement change was YC, XC and YAC. Solid stool appeared at 30 d, fecal scores were increased. Transfer time between mouth and anal was significantly extended, small intestinal propulsion rate were significantly decreased(P < 0.05, P < 0.01). Water content in stool were significantly decreased in three type models(P < 0.05, P < 0.01), the content of water in colon were decreased in XC and YAC group (P < 0.05, P < 0.01). The colonic gland and goblet cells were narrowed in some extent, the mucus excretion were decreased. The levels of aquaporin-2 expressions in proximal and distal colon of rats were increased(P < 0.05, P < 0.01), increasing order of AQP2 expression in proximal colon was YAC, YC and XC, increasing order of AQP2 expression in distal colon was YAC, XC and YC. Long term stimulation of complex factors could induce Ti-Xu with constipation animal model, and there were some differences in colonic motility, water metabolism, colonic mucus secretion and AQP2 in rats.

Intestinal Muc2 mucin O-glycosylation is affected by microbiota and regulated by differential expression of glycosyltranferases.

Intestinal cells are covered by mucus. In the small intestine, a single unattached mucus is present whereas the colon has both an inner attached mucus layer and an outer loose mucus. The attached mucus of the colon is impenetrable to bacteria while the loose mucus acts as a habitat for commensal bacteria. In germ-free (GF) mice, small intestinal mucus is attached to the epithelium and the inner colon mucus is penetrable. O-glycosylation plays an important role in the host-microbiota interactions as the commensal bacteria use glycans as nutrient sources and attachment sites. While mucus protein composition is relatively homogenous along the intestine, its main component the Muc2 mucin shows regiospecific O-glycan patterns. We have now analyzed the glycosyltransferase relative concentrations in the epithelial cells along the intestine in GF and conventionally raised mice and compared this with the O-glycans formed. As Muc2 is the main O-glycosylated product in mucus, we made the simplified assumption that most of the glycosyltransferases found in the epithelial cells are involved in Muc2 O-glycan biosynthesis. The O-glycosyltransferase abundances along the intestine correlated well with the Muc2 O-glycan patterns. Some of the glycosyltransferases involved in the O-glycan elongation were decreased in GF mice, something that is in concordance with the observed shorter Muc2 O-glycans.

Relationship between colonic inner mucus layer and pathogenesis of ulcerative colitis

Relationship between colonic inner mucus layer and pathogenesis of ulcerative colitis

Carbohydrate composition of rat intestine surface mucus layer after ceftriaxone treatment.

The epidemiological studies have shown that antibiotic treatment increases the susceptibility to inflammatory bowel disease development. The disturbance of mucus layer integrity might be one of the possible mechanisms. The aim of the present study was to investigate the effect of antibiotic ceftriaxone treatment on glycoproteins level and its carbohydrate composition in surface mucus layer of rat intestine. The study was done on male Wistar rats (140-160 g). Ceftriaxone (300 mg/kg, i.m.) was administered once a day for 14 days. The surface mucus from terminal ileum and colon were collected on the 15th, 29th and 72nd days of the experiment. Total level of mucus glycoproteins, hexoses, hexosamines, fucose and sialic acids were measured. Ceftriaxone administration did not affect the levels of glycoproteins in rat ileum. In the colon, the levels of glycoprotein were 1.3-fold decreased (Р < 0.05) on the 72nd day of the experiment. These changes were accompanied by the 1.2-fold decrease of hexoses (Р < 0.05) and 3.1-fold (Р < 0.05) decrease of fucose level and 1.5-fold (Р < 0.05) increase of the levels of sialic acids in the surface mucus of the rat colon. Thus, ceftriaxone administration induces the long-term changes in the levels of glycoproteins and carbohydrates composition in the rat colon surface mucus. This could potentially explain the susceptibility to inflammatory bowel disea­ses development.