Composition of human colonic mucin. Selective alteration in inflammatory bowel disease

Purified mucins in drug delivery research

One of the main challenges in the field of drug delivery remains the development of strategies to efficiently transport pharmaceuticals across mucus barriers, which regulate the passage and retention of molecules and particles in all luminal spaces of the body. A thorough understanding of the molecular mechanisms, which govern such selective permeability, is key for achieving efficient translocation of drugs and drug carriers. For this purpose, model systems based on purified mucins can contribute valuable information. In this review, we summarize advances that were made in the field of drug delivery research with such mucin-based model systems: First, we give an overview of mucin purification procedures and discuss the suitability of model systems reconstituted from purified mucins to mimic native mucus. Then, we summarize techniques to study mucin binding. Finally, we highlight approaches that made use of mucins as building blocks for drug delivery platforms or employ mucins as active compounds.

Vibrio cholerae motility in aquatic and mucus-mimicking environments

Cholera disease is caused by Vibrio cholerae infecting the lining of the small intestine and results in severe diarrhea. V. cholerae’s swimming motility is known to play a crucial role in pathogenicity and may aid the bacteria in crossing the intestinal mucus barrier to reach sites of infection, but the exact mechanisms are unknown. The cell can be either pushed or pulled by its single polar flagellum, but there is no consensus on the resulting repertoire of motility behaviors. We use high-throughput three-dimensional (3D) bacterial tracking to observe V. cholerae swimming in buffer, in viscous solutions of the synthetic polymer PVP, and in mucin solutions that may mimic the host environment. We perform a statistical characterization of its motility behavior on the basis of large 3D trajectory data sets. We find that V. cholerae performs asymmetric run-reverse-flick motility, consisting of a sequence of a forward run, reversal, and a shorter backward run, followed by a turn by approximately 90°, called a flick, preceding the next forward run. Unlike many run-reverse-flick swimmers, V. cholerae’s backward runs are much shorter than its forward runs, resulting in an increased effective diffusivity. We also find that the swimming speed is not constant but subject to frequent decreases. The turning frequency in mucin matches that observed in buffer. Run-reverse-flick motility and speed fluctuations are present in all environments studied, suggesting that these behaviors also occur in natural aquatic habitats as well as the host environment.

IMPORTANCE Cholera disease produces vomiting and severe diarrhea and causes approximately 100,000 deaths per year worldwide. The disease is caused by the bacterium Vibrio cholerae colonizing the lining of the small intestine. V. cholerae’s ability to swim is known to increase its infectivity, but the underlying mechanisms are not known. One possibility is that swimming aids in crossing the protective mucus barrier that covers the lining of the small intestine. Our work characterizing how V. cholerae swims in environments that mimic properties of the host environment may advance the understanding of how motility contributes to infection.

Intestinal Organoids as a Novel Complementary Model to Dissect Inflammatory Bowel Disease

Inflammatory bowel diseases (IBDs) include colitis ulcerosa and Crohn's disease, besides the rare microscopic colitis. Both diseases show a long-lasting, relapsing-remitting, or even chronic active course with tremendous impact on quality of life. IBDs frequently cause disability, surgical interventions, and high costs; as in other autoimmune diseases, their prevalent occurrence at an early phase of life raises the burden on health care systems. Unfortunately, our understanding of the pathogenesis is still incomplete and treatment therefore largely focuses on suppressing the resulting excessive inflammation. One obstacle for deciphering the causative processes is the scarcity of models that parallel the development of the disease, since intestinal inflammation is mostly induced artificially; moreover, the intestinal epithelium, which strongly contributes to IBD pathogenesis, is difficult to assess. Recently, the development of intestinal epithelial organoids has overcome many of those problems. Here, we give an overview on the current understanding of the pathogenesis of IBDs with reference to the limitations of previous well-established experimental models. We highlight the advantages and detriments of recent organoid-based experimental setups within the IBD field and suggest possible future applications.

Recent Advances in Understanding the Pathogenesis of Cardiovascular Diseases and Development of Treatment Modalities

Cardiovascular Diseases (CVDs) are a leading cause of morbidity and mortality worldwide. The underlying pathology for cardiovascular disease is largely atherosclerotic in nature and the steps include fatty streak formation, plaque progression and plaque rupture. While there is optimal drug therapy available for patients with CVD, there are also underlying drug delivery obstacles that must be addressed. Challenges in drug delivery warrant further studies for the development of novel and more efficacious medical therapies. An extensive understanding of the molecular mechanisms of disease in combination with current challenges in drug delivery serves as a platform for the development of novel drug therapeutic targets for CVD. The objective of this article is to review the pathogenesis of atherosclerosis, first-line medical treatment for CVD, and key obstacles in an efficient drug delivery.

Towards bioinspired in vitro models of intestinal mucus

Intestinal mucus is a biological structure that acts as a barrier between the external environment and the epithelium. It actively selects nutrient and drug intake, regulates the symbiosis with the intestinal microbiota and keeps the epithelium protected from the attack of pathogens. All these functions are closely connected to the chemical and structural complexity of this biological material, on which its viscoelastic and diffusive properties depend. Many models have been proposed to replicate these characteristics using glycoproteins in solution and possibly the addition of other mucus components, such as lipids and other proteins. In the field of mucus modelling, an overall view of the mucus as a material, having its own viscous, rheological and diffusive characteristics, has been undersized with respect to a pure biological-functional analysis. In this review, we propose a description of the mucus as a biomaterial, including a presentation of its chemical and structural complexity, and of its main viscoelastic-diffusive properties, in order to provide a synthesis of the characteristics necessary for the engineering of more advanced mucus models.

Intestinal mucus is an anisotropic biological structure that acts as a barrier between the external environment and the epithelium.

Utilization of carbon sources by clinical isolates of Aeromonas

Bacteria in the genus Aeromonas are primarily aquatic organisms; however, some species can cause diseases in humans, ranging from wound infections to septicemia, of which diarrhea is the most common condition. The ability to use a variety of carbon substrates is advantageous for pathogenic bacteria. Therefore, we used Biolog GN2 microplates to analyze the ability of 103 clinical, predominantly diarrheal, isolates of Aeromonas to use various carbon sources, and we verified whether, among the substrates metabolized by these strains, there were some endogenous to the human intestine. The results indicate that Aeromonas present great diversity in the utilization of carbon sources, and that they preferentially use carbohydrates and amino acids as carbon sources. Among the carbon sources metabolized by Aeromonas in vitro, some were found to be components of intestinal mucin, including aspartic acid, glutamic acid, l-serine, galactose, N-acetyl-glucosamine, and glucose, which were used by all strains tested. Additionally, mannose, d-serine, proline, threonine, and N-acetyl-galactosamine were used by several strains. The potential to metabolize substrates endogenous to the intestine may contribute to Aeromonas' capacity to grow in and colonize the intestine. We speculate that this may help explain the ability of Aeromonas to cause diarrhea.

TGF-β Signaling in Dendritic Cells Governs Colonic Homeostasis by Controlling Epithelial Differentiation and the Luminal Microbiota

Dendritic cells (DCs) mediate host immune responses to gut microbes and play critical roles in inflammatory bowel disease. In this study, we examined the role of TGF-β signaling in DCs in colonic homeostasis. CD11c-cre Tgfbr2fl/fl mice developed spontaneous colitis, and CD11c-cre Tgfbr2fl/+ mice exhibited susceptibility to dextran sulfate sodium–induced colitis. Colitis in these mice was characterized by goblet cell depletion and dysbiosis caused by Enterobacteriaceae enrichment. Wild-type mice gavaged with Enterobacteriaceae from CD11c-cre Tgfbr2fl/fl mice feces showed severe colitis after dextran sulfate sodium treatment, whereas those treated with Notch inhibitor exhibited attenuated colonic injury with increased goblet cell numbers, thickened mucus layer, and fewer fecal Enterobacteriaceae. Wild-type mice transplanted with CD11c-cre Tgfbr2fl/fl bone marrow developed colitis showing increased Jagged1 and Jagged2 in DCs, increased Hes1 levels in epithelium, and goblet cell depletion. These findings suggest that TGF-β signaling in DCs regulates intestinal homeostasis by modulating epithelial cell differentiation and fecal microbiota.

Curcumin half analog modulates interleukin-6 and tumor necrosis factor-alpha in inflammatory bowel disease

BACKGROUND

The present study was aimed at examining the effect of dehydrozingerone (DHZ), half analogue of curcumin which is the active constituent of turmeric (Curcuma longa) in the di-nitrochlorobenzene (DNCB) induced model for inflammatory bowel disease (IBD).

MATERIALS AND METHODS

Male Wistar rats (200-220 g) were divided into four groups (n = 6). Chemical induction of IBD was done by sensitizing with 300 µL of 20 g/L of DNCB (in acetone) onto the nape of rats for 14 days followed by intra-colonic instillation of 250 µL of DNCB (0.1% DNCB in 50% alcohol) solution on day 15. Rats in Group 1 (normal control) and Group 2 (DNCB control) were treated with vehicle. Rats in Group 3 were treated with DHZ (100 mg/kg, p.o.; 8 days) and Group 4 animals were treated with sulfasalazine (SS) (100 mg/kg, p.o.; 8 days). On 24(th) day, the rats were killed, colon removed and the macroscopic, biochemical, and histopathological evaluations were performed.

RESULTS

The levels of myeloperoxidase, thiobarbituric acid reactive substrate, and nitrite increased significantly (P < 0.05) in the DNCB group whereas reduced significantly in the DHZ and SS treated groups. Serum nitrite levels were found to be insignificant between the different groups. Interleukin-6, tumor necrosis factor-alpha level was significantly high in the DNCB group.

CONCLUSION

These findings show that DHZ can be a promising molecule for the treatment of IBD.

Colitogenic Bacteroides thetaiotaomicron Antigens Access Host Immune Cells in a Sulfatase-Dependent Manner via Outer Membrane Vesicles

Microbes interact with the host immune system via several potential mechanisms. One essential step for each mechanism is the method by which intestinal microbes or their antigens access specific host immune cells. Using genetically susceptible mice (dnKO) that develop spontaneous, fulminant colitis, triggered by Bacteroides thetaiotaomicron (B. theta), we investigated the mechanism of intestinal microbial access under conditions that stimulate colonic inflammation. B. theta antigens localized to host immune cells through outer membrane vesicles (OMVs) that harbor bacterial sulfatase activity. We deleted the anaerobic sulfatase maturating enzyme (anSME) from B. theta, which is required for post-translational activation of all B. theta sulfatase enzymes. This bacterial mutant strain did not stimulate colitis in dnKO mice. Lastly, access of B. theta OMVs to host immune cells was sulfatase dependent. These data demonstrate that bacterial OMVs and associated enzymes promote inflammatory immune stimulation in genetically susceptible hosts.

The levels of Brachyspira hyodysenteriae binding to porcine colonic mucins differ between individuals, and binding is increased to mucins from infected pigs with de novo MUC5AC synthesis

Brachyspira hyodysenteriae colonizes the pig colon, resulting in mucohemorrhagic diarrhea and growth retardation. Fecal mucus is a characteristic feature of swine dysentery; therefore, we investigated how the mucin environment changes in the colon during infection with B. hyodysenteriae and how these changes affect this bacterium's interaction with mucins. We isolated and characterized mucins, the main component of mucus, from the colon of experimentally inoculated and control pigs and investigated B. hyodysenteriae binding to these mucins. Fluorescence microscopy revealed a massive mucus induction and disorganized mucus structure in the colon of pigs with swine dysentery. Quantitative PCR (qPCR) and antibody detection demonstrated that the mucus composition of pigs with swine dysentery was characterized by de novo expression of MUC5AC and increased expression of MUC2 in the colon. Mucins from the colon of inoculated and control pigs were isolated by two steps of isopycnic density gradient centrifugation. The mucin densities of control and inoculated pigs were similar, whereas the mucin quantity was 5-fold higher during infection. The level of B. hyodysenteriae binding to mucins differed between pigs, and there was increased binding to soluble mucins isolated from pigs with swine dysentery. The ability of B. hyodysenteriae to bind, measured in relation to the total mucin contents of mucus in sick versus healthy pigs, increased 7-fold during infection. Together, the results indicate that B. hyodysenteriae binds to carbohydrate structures on the mucins as these differ between individuals. Furthermore, B. hyodysenteriae infection induces changes to the mucus niche which substantially increase the amount of B. hyodysenteriae binding sites in the mucus.

Mucosal barrier, bacteria and inflammatory bowel disease: possibilities for therapy

The mucosal barrier has three major components, the mucus layer, the epithelial glycocalyx and the surface epithelium itself, whose integrity largely depends on tight junction function. In health, there is relatively little direct interaction between the luminal microbiota and the epithelium - the continuous mucus layer in the colon keeps the surface epithelium out of contact with bacteria and the ileo-caecal valve ensures that the distal small intestine is relatively microbe free. Most interaction takes place at the Peyer's patches in the distal ileum and their smaller colonic equivalents, the lymphoid follicles. Peyer's patches are overlain by a 'dome' epithelium, 5% of whose cells are specialised M (microfold) epithelial cells, which act as the major portal of entry for bacteria. There are no goblet cells in the dome epithelium and M cells have a very sparse glycocalyx allowing easy microbial interaction. It is intriguing that the typical age range for the onset of Crohn's disease (CD) is similar to the age at which the number of Peyer's patches is greatest. Peyer's patches are commonly the sites of the initial lesions in CD and the 'anti-pancreatic' antibody associated with CD has been shown to have as its epitope the glycoprotein 2 that is the receptor for type-1 bacterial fimbrial protein (fimH) on M cells. There are many reasons to believe that the mucosal barrier is critically important in the pathogenesis of inflammatory bowel disease (IBD). These include (i) associations between both CD and ulcerative colitis (UC) with genes that are relevant to the mucosal barrier; (ii) increased intestinal permeability in unaffected relatives of CD patients; (iii) increased immune reactivity against bacterial antigens, and (iv) animal models in which altered mucosal barrier, e.g. denudation of the mucus layer associated with oral dextran sulphate in rodents, induces colitis. Whilst some IBD patients may have genetic factors leading to weakening of the mucosal barrier, it is likely that environmental factors may be even more important. Some may be subtle and indirect, e.g. the effects of stress on the mucosa barrier, whilst others may be more obvious, e.g. the effect of pathogen-related gastroenteritis, known often to act as trigger for IBD relapse. We have also been very interested in the potentially harmful effects of ingested detergents - either by contamination of cutlery by inadequate rinsing or via ingestion of processed foods containing permitted emulsifiers. In vitro and ex vivo studies show that even very small trace amounts of these surfactants can greatly increase bacterial translocation. Implications for therapy are not yet so obvious. We advise our IBD patients to avoid processed foods containing emulsifiers and to rinse their dishes well - whilst accepting that there is no direct evidence yet to support this. Therapies that aim to enhance the mucosal barrier have yet to come to market, but trials of enteric-delivered phosphatidylcholine in UC are promising. The faecal concentration of mucus-degrading bacterial enzymes (particularly proteases, sulphatases and sialidases) correlates with disease activity in UC, and these represent good targets for therapy.

Modulatory effects of sesamol in dinitrochlorobenzene-induced inflammatory bowel disorder in albino rats

BACKGROUND

Inflammatory bowel disease (IBD) is a chronic inflammatory condition of gastrointestinal tract of immune, genetic and environmental origin. In the present study, we examined the effect of sesamol (SES), the main anti-oxidative constituent of Sesamum indicum (sesame seed) Linn. in the dinitrochlorobenzene (DNCB)-induced model for IBD in rats.

METHODS

The groups were divided into normal control, DNCB control, SES and sulfasalazine (SS). On day 24, the rats were killed, colon removed and the macroscopic, biochemical and histopathological evaluations were performed.

RESULTS

The levels of MPO, TBARS and nitrite increased significantly (p < 0.05) in the DNCB group, whereas reduced significantly in the SES, SS treated groups. Serum nitrite levels were found to be insignificant between the different groups. IL-6 and TNF-α levels were significantly high in the DNCB group.

CONCLUSIONS

We conclude the mucosal protective effect of SES on colon due to its potent antioxidant actions. Further investigation is required in a chronic model of different rodent strain for its role involved in the cytokine pathway.

Investigation of sesamol on myeloperoxidase and colon morphology in acetic acid-induced inflammatory bowel disorder in albino rats

Background. Inflammatory bowel disease (IBD) is a chronic inflammatory disorder of gastrointestinal tract of immune, genetic, and environmental origin. In the present study, we examined the effects of sesamol (SES), which is the active constituent of sesame oil in the acetic acid (AA) induced model for IBD in rats. Methods. The groups were divided into normal control, AA control, SES, and sulfasalazine (SS). On day 7, the rats were killed, colon was removed, and the macroscopic, biochemical, and histopathological evaluations were performed. Results. The levels of MPO, TBARS, and tissue nitrite increased significantly (P < 0.05) in the AA group whereas they reduced significantly in the SES and SS treated groups. Serum nitrite levels were found to be insignificant between the different groups. Conclusions. The mucosal protective effects of sesamol in IBD are due to its potential to reduce the myeloperoxidase and nitrite content.

Near infrared optical visualization of epidermal growth factor receptors levels in COLO205 colorectal cell line, orthotopic tumor in mice and human biopsies

In this study, we present the applicability of imaging epidermal growth factor (EGF) receptor levels in preclinical models of COLO205 carcinoma cells in vitro, mice with orthotopic tumors and ex vivo colorectal tumor biopsies, using EGF-labeled with IRDye800CW (EGF-NIR). The near infrared (NIR) bio-imaging of COLO205 cultures indicated specific and selective binding, reflecting EGF receptors levels. In vivo imaging of tumors in mice showed that the highest signal/background ratio between tumor and adjacent tissue was achieved 48 hours post-injection. Dissected colorectal cancer tissues from different patients demonstrated ex vivo specific imaging using the NIR bio-imaging platform of the heterogeneous distributed EGF receptors. Moreover, in the adjacent gastrointestinal tissue of the same patients, which by Western blotting was demonstrated as EGF receptor negative, no labeling with EGF-NIR probe was detected. Present results support the concept of tumor imaging by measuring EGF receptor levels using EGF-NIR probe. This platform is advantageous for EGF receptor bio-imaging of the NCI-60 recommended panel of tumor cell lines including 6-9 colorectal cell lines, since it avoids radioactive probes and is appropriate for use in the clinical setting using NIR technologies in a real-time manner.

Goblet cells and mucins: role in innate defense in enteric infections

Goblet cells reside throughout the gastrointestinal (GI) tract and are responsible for the production and preservation of a protective mucus blanket by synthesizing and secreting high molecular weight glycoproteins known as mucins. The concept of the mucus layer functioning as a dynamic protective barrier is suggested by studies showing changes in mucins in inflammatory conditions of the GI tract, by the altered goblet cell response in germ-free animals, and by the enhanced mucus secretion seen in response to infections. The mucin-containing mucus layer coating the GI epithelium is the front line of innate host defense. Mucins are likely to be the first molecules that invading pathogens interact with at the cell surface and thus, can limit binding to other glycoproteins and neutralize the pathogen. This review will focus on what is known about goblet cell response in various GI infections and the regulatory networks that mediate goblet cell function and mucin production in response to intestinal insults. In addition, we describe the current knowledge on the role of mucins in intestinal innate defense. It is the aim of this review to provide the readers with an update on goblet cell biology and current understanding on the role of mucins in host defense in enteric infections.

Glycosylation of IgA1 and pathogenesis of IgA nephropathy

IgA nephropathy, described in 1968 as IgA-IgG immune-complex disease, is an autoimmune disease. Galactose-deficient IgA1 is recognized by unique autoantibodies, resulting in the formation of pathogenic immune complexes that ultimately induce glomerular injury. Thus, formation of the galactose-deficient IgA1-containing immune complexes is a critical factor in the pathogenesis of IgA nephropathy. Studies of molecular defects of IgA1 can define new biomarkers specific for IgA nephropathy that can be developed into clinical assays to aid in the diagnosis, assessment of prognosis, and monitoring of disease progression.

New insights into the role of fatty acids in the pathogenesis and resolution of inflammatory bowel disease

Dietary and endogenously modified lipids modulate inflammation by functioning as intra- and intercellular signaling molecules. Proinflammatory lipid mediators such as the eicosanoids compete against the signaling actions of newly discovered modified fatty acids that act to resolve inflammation. In inflammatory bowel disease, multiple aberrancies in lipid metabolism have been discovered, which shed further light on the pathogenesis of intestinal inflammation. Mechanisms by which lipids modulate inflammation, abnormalities of lipid metabolism in the setting of inflammatory bowel disease, and potential therapeutic application of lipid derivatives in this setting are discussed.

Loss of intestinal core 1-derived O-glycans causes spontaneous colitis in mice

Mucin-type O-linked oligosaccharides (O-glycans) are primary components of the intestinal mucins that form the mucus gel layer overlying the gut epithelium. Impaired expression of intestinal O-glycans has been observed in patients with ulcerative colitis (UC), but its role in the etiology of this disease is unknown. Here, we report that mice with intestinal epithelial cell-specific deficiency of core 1-derived O-glycans, the predominant form of O-glycans, developed spontaneous colitis that resembled human UC, including massive myeloid infiltrates and crypt abscesses. The colitis manifested in these mice was also characterized by TNF-producing myeloid infiltrates in colon mucosa in the absence of lymphocytes, supporting an essential role for myeloid cells in colitis initiation. Furthermore, induced deletion of intestinal core 1-derived O-glycans caused spontaneous colitis in adult mice. These data indicate a causal role for the loss of core 1-derived O-glycans in colitis. Finally, we detected a biosynthetic intermediate typically exposed in the absence of core 1 O-glycan, Tn antigen, in the colon epithelium of a subset of UC patients. Somatic mutations in the X-linked gene that encodes core 1 β1,3-galactosyltransferase-specific chaperone 1 (C1GALT1C1, also known as Cosmc), which is essential for core 1 O-glycosylation, were found in Tn-positive epithelia. These data suggest what we believe to be a new molecular mechanism for the pathogenesis of UC.

Intestinal Host-Microbe Interactions under Physiological and Pathological Conditions

The intestinal mucosa is unique in that it can be tolerant to the resident, symbiotic microbiota but remaining, at the same time, responsive to and able to fight pathogens. The close interaction between host-symbiotic microbiota at the mucosal level poses important challenges since microbial breaches through the gut barrier can result in the breakdown of gut homeostasis. In this paper, hosts-integrated components that help to preserve intestinal homeostasis including barrier and immune function are discussed. In addition global alterations of the microbiota that can play a role in the initiation of an exaggerated inflammatory response through an abnormal signaling of the innate and adaptive immune response are briefly described.

Identification of complement C3 as an autoantigen in inflammatory bowel disease

OBJECTIVE

Autoantibodies against goblet cells in the gastrointestinal mucosa have been described in patients with inflammatory bowel disease (IBD) but a corresponding autoantigen has not yet been identified. The aim of this study was to identify such an antigen.

METHODS

First, 10 candidate autoantigens were discarded based on double stainings of appendiceal sections and a mucin-producing cell line (HT29-mtx). Second, an appendiceal cDNA library was immunoscreened with IBD sera.

RESULTS

Three out of 48 positive clones were identified as complement C3. Using immunoprecipitation of in vitro transcribed and translated C3, seven of 17 primary sclerosing cholangitis patient sera, 15 of 65 IBD sera, and none out of 54 sera from healthy blood donors showed C3 immunoreactivity. The results were confirmed using western blot and an enzyme-linked immunosorbent assay with alternative sources of C3 protein.

CONCLUSION

In conclusion, we have identified complement C3 as a potential autoantigen in IBD and primary sclerosing cholangitis.

Antibody to tropomyosin isoform 5 and complement induce the lysis of colonocytes in ulcerative colitis

OBJECTIVES

Tropomyosins (TMs) are cytoskeletal microfilament proteins present in all eukaryotic cells. Human TM isoform 5 (hTM5) is the predominant isoform in colonic epithelial cells. Antibodies against hTM5 are found both in the sera and in the mucosa of patients with ulcerative colitis (UC) but not Crohn's disease (CD). We investigated whether anti-hTM5 autoantibodies are pathogenic.

METHODS

Normal-appearing colonic mucosal biopsy specimens were incubated with autologous serum. After 45 min, deposition of the complement component C3b was identified by indirect immunofluorescence assay (IFA). Additional specimens were incubated with autologous serum fixed in formalin, and their architecture was examined by hematoxylin and eosin (H&E) staining.

RESULTS

For 79% of UC patients, autologous serum caused C3b staining along the colonic epithelium. Recombinant hTM5 or anti-hTM5 monoclonal antibody blocked serum-induced C3b deposition. Immunoglobulin G (IgG) antibody and affinity-purified anti-hTM5 IgG antibody from UC sera with complement caused C3b deposition, indicating specificity of hTM5 as an autoantigen. When analyzed by H&E staining, sera obtained from 71% of UC patients caused a significant loss of epithelium. This process was inhibited by Fc fragments, indicating that it is complement mediated. With medium, normal, or CD serum, there was no C3b deposition or morphological changes of the colonic epithelium, indicating disease specificity. The ileal mucosa was not affected by UC sera, suggesting specificity for the colon. In UC mucosa, expression of hTM5 increased.

CONCLUSIONS

hTM5 acts as an autoantigen in UC. hTM5-specific IgG autoantibody in sera from UC patients induces C3b deposition and destruction of colonic epithelial cells, suggesting a direct pathogenic effect. If used as a diagnostic test to distinguish UC from CD, IFA would have 79% sensitivity and 100% specificity. Development of blocking antibodies may lead to novel therapies.

Pancreatic autoantibodies are associated with reactivity to microbial antibodies, penetrating disease behavior, perianal disease, and extraintestinal manifestations, but not with NOD2/CARD15 or TLR4 genotype in a Hungarian IBD cohort

BACKGROUND

Pancreatic autoantibodies (PAB) and goblet cell autoantibodies (GAB) are specific for Crohn's disease (CD) and ulcerative colitis (UC), but the sensitivity alone is low. Conventional antibodies and carbohydrates (glycans) are associated with disease phenotype and may be of diagnostic importance in inflammatory bowel disease (IBD). Our aim was to determine the accuracy of PAB and GAB autoantibodies as well as to study relevant phenotype-serotype associations.

METHODS

A Hungarian study cohort of 1092 subjects, including 689 well-characterized, unrelated IBD patients (CD: 579, m/f ratio: 274/305, duration: 7.9 +/- 11.2 years; UC: 110, m/f ratio: 53/57, duration: 8.9 +/- 9.8 years), 139 celiac patients, 100 healthy, and 64 non-IBD gastrointestinal controls were investigated. Sera were assayed for PAB-GAB IgA/IgG, anti-Omp, anti-Saccharomyces cerevisiae antibodies (ASCA), and anti-glycans. TLR4 and NOD2/CARD15 was tested by polymerase chain reaction / restriction fragment length polymorphism (PCR-RFLP). Detailed clinical phenotypes were determined.

RESULTS

The prevalence of PAB was significantly more frequent in CD (41.1%) versus UC (22.7%), celiac (22.3%), and controls (8% and 4.6%, P < 0.01 for each), while GAB detection was poor in all groups except UC (15.4%). In CD the combination of PAB and/or anti-glycans/ASCA increased the sensitivity to 72% and 59%, respectively, for isolated colonic disease. PAB was associated to gylcans (odds ratio [OR] 1.74,P = 0.002), ASCA IgG/IgA (OR 1.75, P = 0.002), Omp (OR 1.86, P = 0.001) as well as perforating, perianal disease, arthritis, ocular, and cutaneous manifestations (P = 0.002-0.032). In contrast, PAB and GAB antibodies were not associated with NOD2/CARD15 or TLR4, response to medical therapy, or need for surgery. No associations were found in UC.

CONCLUSIONS

PAB autoantibodies in combination with ASCA or anti-glycan antibodies increase the sensitivity for detecting CD, especially isolated colonic CD. Antibody response to PAB was associated with complicated disease phenotype and extraintestinal manifestations in this Eastern European IBD cohort.

Role of the innate immune system in the pathogenesis of inflammatory bowel disease

Crohn disease and ulcerative colitis are chronic inflammatory diseases of the intestinal tract commonly denoted as inflammatory bowel diseases. It has been proposed that these diseases result from aberrant mucosal immune responses to nonpathogenic microbial residents of the intestines. Recently, it was established that continuous interactions between the innate and the adaptive intestinal immune cells and the microbiota are directly involved in maintaining the physiological noninflammatory state of the intestinal mucosa. In light of the complexity of this mucosal homeostasis, it is astonishing that the inflammatory bowel diseases are relatively rare. Recently, altered functions of the innate immune system have been identified. As such, both hyperresponsiveness and hyporesponsiveness of innate cells have been implicated in the pathogenesis of inflammatory bowel diseases.

Vitamin C protects against ionizing radiation damage to goblet cells of the ileum in rats

The aim of the present study was to evaluate the radioprotective effect of vitamin C on gamma-radiation-induced damage to goblet cells of the ileum. Thirty male Wistar albino rats weighing between 250 and 300 g were randomized into the following study groups: I, control; II, single dose radiation treated; III, two dose radiation treated with a 4-day interval between doses; IV, single dose radiation treated with vitamin C; V, two dose radiation treated with vitamin C. Each group contained six animals. The rats in groups IV and V were given a daily dose of 100 mg/kg of vitamin C for 14 and 18 days, respectively. During the vitamin C administration period, the rats in group IV were exposed in the abdominal area to a gamma-ray dose of 5 Gy on day 10 and group V was exposed to same dose of radiation on days 10 and 14. Irradiation and treatment groups were decapitated 4 days after exposure to single or two dose irradiation and ileum tissues were removed for light and electron microscopic investigation. Single or two dose gamma-irradiation caused a marked intestinal mucosal injury in rats. Radiation produced increases in the number of goblet cells. Using transmission electron microscopy, extensions in the area between the cells, disorders in the microvilli, mitochondrial damage and endoplasmic reticulum (ER) cisternae dilatation were observed. Antioxidant treatment with vitamin C prior to irradiation provided protection against intestinal damage.

Effects of tea catechins on the gastrointestinal mucosa in rats

Although tea catechins are known to exert a potent antiulcer effect on the alimentary tract, there is scant information concerning their effects on normal mucus cell functions. Using original anti-mucin monoclonal antibodies, we studied the influences of long-term administration of catechins on the quantity and quality of mucin in rat gastrointestinal mucosa. Administration of 0.5% tea catechins significantly increased the mucin content of the ileum, but not the stomach. An enzyme-linked immunosorbent assay (ELISA) showed no remarkable qualitative changes in gastric mucin, but a selective increase and decrease in sulfo- and sialomucins, respectively, in the ileum of rats administered catechins. The ELISA results were consistent with both the immunohistochemical findings and the high-iron diamine-alcian blue staining pattern. These findings indicate that tea catechins modulate ileal mucin metabolism in the ileal mucosa, suggesting that further studies focusing on the ileal epithelium will assist in further elucidation of the mechanism of catechin effects.

Physiological changes in the gastrointestinal tract and host protective immunity: learning from the mouse-Trichinella spiralis model

Infection and inflammation in the gastrointestinal (GI) tract induces a number of changes in the GI physiology of the host. Experimental infections with parasites represent valuable models to study the structural and physiological changes in the GI tract. This review addresses research on the interface between the immune system and GI physiology, dealing specifically with 2 major components of intestinal physiology, namely mucin production and muscle function in relation to host defence, primarily based on studies using the mouse-Trichinella spiralis system. These studies demonstrate that the infection-induced T helper 2 type immune response is critical in generating the alterations of infection-induced mucin production and muscle function, and that this immune-mediated alteration in gut physiology is associated with host defence mechanisms. In addition, by manipulating the host immune response, it is possible to modulate the accompanying physiological changes, which may have clinical relevance. In addition to enhancing our understanding of immunological control of GI physiological changes in the context of host defence against enteric infections, the data acquired using the mouse-T. spiralis model provide a basis for understanding the pathophysiology of a wide range of GI disorders associated with altered gut physiology.

Expression of apoptotic epithelial cells within lamina propria beneath the basement membrane triggers dextran sulfate sodium-induced colitis

We postulated that nuclear dust within the lamina propria beneath the basement membrane of the epithelium in colonic mucosa is a form of apoptotic epithelial cells and that its expression triggers dextran sulfate sodium-induced colitis. The aim was to determine the origin of nuclear dust and to explore the correlation between nuclear dust expression and clinicopathologic parameters of colitis. Rats were treated with 3% dextran sulfate sodium. Cells showing double positive staining with cytokeratin and TdT-mediated uUTP-biotin nick-end labeling technique were apoptotic cells derived from epithelial cells. Nuclear dust expression on day 5 correlated with bloody stools and a decrease of mitotic colonic cells just before ulceration. Examination of cultures under light and fluorescent microscopy showed that dextran sulfate sodium caused early apoptosis and late apoptosis or necrosis. Our results suggest that interventions directed toward the apoptotic process may be beneficial in the treatment of ulcerative colitis.

Immunoreactivity against Goblet cells in patients with inflammatory bowel disease

BACKGROUND

A number of autoantibodies have been reported in inflammatory bowel disease (IBD). The aim of this study was to investigate to what extent sera from patients with IBD contain autoantibodies directed against normal human gastrointestinal mucosa.

METHODS

Samples of sera from 50 patients with IBD and 50 healthy subjects were used for immunostaining of normal and affected human gastrointestinal tissues.

RESULTS

Eighty-four percent of the sera from IBD patients showed immunoreactivity against goblet cells in the appendix compared with 8% of the sera from healthy subjects. Goblet cell reactivity of IBD patient sera varied between regions in the gastrointestinal tract. Sera from healthy subjects only reacted with goblet cells in the appendix. In the colon and the appendix, goblet cell reactivity of IBD sera was generally weak at the base of the crypts and gradually increased toward the lumen. Three IBD sera samples reacted with gastrin cells in the antrum. In colon biopsies from patients with ulcerative colitis, immunoreactivity against the remaining goblet cells showed an inverse correlation with inflammatory activity.

CONCLUSIONS

These findings suggest that immunoreactivity against goblet cells may be of central importance in the pathogenesis of IBD. Identification of goblet cell antigens could lead to a better understanding of IBD and provide a new diagnostic tool.

Aberrant mucin assembly in mice causes endoplasmic reticulum stress and spontaneous inflammation resembling ulcerative colitis

BACKGROUND

MUC2 mucin produced by intestinal goblet cells is the major component of the intestinal mucus barrier. The inflammatory bowel disease ulcerative colitis is characterized by depleted goblet cells and a reduced mucus layer, but the aetiology remains obscure. In this study we used random mutagenesis to produce two murine models of inflammatory bowel disease, characterised the basis and nature of the inflammation in these mice, and compared the pathology with human ulcerative colitis.

METHODS AND FINDINGS

By murine N-ethyl-N-nitrosourea mutagenesis we identified two distinct noncomplementing missense mutations in Muc2 causing an ulcerative colitis-like phenotype. 100% of mice of both strains developed mild spontaneous distal intestinal inflammation by 6 wk (histological colitis scores versus wild-type mice, p < 0.01) and chronic diarrhoea. Monitoring over 300 mice of each strain demonstrated that 25% and 40% of each strain, respectively, developed severe clinical signs of colitis by age 1 y. Mutant mice showed aberrant Muc2 biosynthesis, less stored mucin in goblet cells, a diminished mucus barrier, and increased susceptibility to colitis induced by a luminal toxin. Enhanced local production of IL-1beta, TNF-alpha, and IFN-gamma was seen in the distal colon, and intestinal permeability increased 2-fold. The number of leukocytes within mesenteric lymph nodes increased 5-fold and leukocytes cultured in vitro produced more Th1 and Th2 cytokines (IFN-gamma, TNF-alpha, and IL-13). This pathology was accompanied by accumulation of the Muc2 precursor and ultrastructural and biochemical evidence of endoplasmic reticulum (ER) stress in goblet cells, activation of the unfolded protein response, and altered intestinal expression of genes involved in ER stress, inflammation, apoptosis, and wound repair. Expression of mutated Muc2 oligomerisation domains in vitro demonstrated that aberrant Muc2 oligomerisation underlies the ER stress. In human ulcerative colitis we demonstrate similar accumulation of nonglycosylated MUC2 precursor in goblet cells together with ultrastructural and biochemical evidence of ER stress even in noninflamed intestinal tissue. Although our study demonstrates that mucin misfolding and ER stress initiate colitis in mice, it does not ascertain the genetic or environmental drivers of ER stress in human colitis.

CONCLUSIONS

Characterisation of the mouse models we created and comparison with human disease suggest that ER stress-related mucin depletion could be a fundamental component of the pathogenesis of human colitis and that clinical studies combining genetics, ER stress-related pathology and relevant environmental epidemiology are warranted.

NV-52

NV-52, a synthetic flavonoid derivative, is a selective thromboxane synthase (TXS) inhibitor that is being developed as a treatment for inflammatory bowel disease. NV-52 selectively inhibits TXS in vitro in physiological relevant concentrations, causing a reduction in thromboxane B(2) of </= 40% in association with an increase in prostaglandin E(2). NV-52 is effective in suppressing colonic inflammation in a murine model of inflammatory bowel disease. NV-52 has not demonstrated any toxicity in in vitro and animal toxicological studies, and has been administered to normal volunteers in a Phase I clinical trial without detectable adverse effects. NV-52 is well absorbed and a single dose of 400 mg p.o. produced a plasma concentration that is comparable with the concentrations that have been shown to produce significant TXS inhibition in vitro.

Polyethylene glycol enhances colonic barrier function and ameliorates experimental colitis in rats

OBJECTIVE

Polyethylene glycol (PEG) has been suggested to protect against pathogen colonization by improving colonic barrier function. We aimed to establish whether PEG 4000 affects colonic barrier function and the development of colitis induced by 2,4,6-trinitrobenzenesulfonic acid (TNBS) in rats.

MATERIALS AND METHODS

PEG was included in the drinking water for a period of 48 h before intracolonic administration of TNBS.

RESULTS AND DISCUSSION

PEG increased colonic surface hydrophobicity and diminished luminal bacterial load. Moreover, PEG markedly reduced mucosal damage and inflammation induced by TNBS. This protection effect appeared to be independent of its laxative properties since the laxatives mannitol or senna extracts had no effect on TNBS colitis. Using everted colonic sacs, pretreatment with PEG produced a lasting reduction in epithelial permeability to mannitol and dextran-70 K that correlated with decreased surface hydrophobicity.

CONCLUSION

Our results suggest that the protective effect of PEG on TNBS colitis is associated with reinforcement of the epithelial barrier.

Altered colonic glycoprotein expression in unaffected monozygotic twins of inflammatory bowel disease patients

BACKGROUND AND AIMS

Previous chromatographic analysis of colonic mucins from monozygotic twins with inflammatory bowel disease (IBD) suggested a genetic mucin alteration in ulcerative colitis (UC). This study explores this further by assessing mucosal expression of the oncofetal carbohydrate antigen TF (galactose beta1, 3 N-acetylgalactosamine alpha-), among the same IBD twins.

MATERIALS AND METHODS

Formalin fixed paraffin embedded rectal biopsies were studied from 22 monozygotic twin pairs with IBD. These included eight UC twin pairs and 14 Crohn's disease (CD) twin pairs, with six pairs concordant for disease and 16 unaffected twin siblings. Closely adjacent sections were assessed by peanut lectin histochemistry for TF expression and immunohistochemically for nuclear factor kappaB (NFkappaB) activation with investigators blinded to the diagnosis.

RESULTS

Unaffected twins were almost all TF positive (15/16) compared with 5/29 histologically normal controls (p<0.0001). Unaffected UC (7/8) and CD twins (8/8) were similarly TF positive. TF positivity was confined mainly to the superficial epithelium and absent from the stem cell compartment of the lower crypts, suggesting that glycosylation changes are acquired rather than genetically determined. Activated NFkappaB was present in the surface epithelium of mucosal biopsies from 13/14 unaffected IBD twins but in only 6/22 histologically normal controls (p=0.0004). All 22 affected IBD twins were TF positive and 18 were positive for activated NFkappaB.

CONCLUSIONS

Altered mucosal glycosylation in unaffected identical twins of IBD patients was confirmed in this study. This occurred in both UC and CD twins. The changes are probably acquired rather than congenital and may reflect "preinflammatory" NFkappaB activation.

Analysis of mucin composition in gastric juices of chronic rheumatic patients with upper gastrointestinal damage

Assessment of the mucin subclasses in the gastric juices of severe chronic rheumatoid arthritis (RA) patients was compared with non-RA cases which received the eradication treatment of Helicobacter pylori (H. pylori). Gastric juice samples were obtained from 8 RA patients (5 for H. pylori-negative and 3 for H. pylori-positive) and 5 control subjects in which we confirmed the successful eradication of H. pylori. The gastric luminal mucins were extracted and isolated by the ethanol precipitation method. These mucin solutions were digested with chymotrypsin, dialyzed, lyophilized, and redissolved. The obtained specimen was applied to an ion exchange column containing DEAE-Sepharose CL-6B and eluted with a discontinuous salt gradient in three salt steps. The gastric luminal mucins were divided into three fractions based on the distinctive sialic acid content. The proportion of acidic mucin rich in sialic acid from the gastric juice of RA patients without the H. pylori infection was significantly lower than those RA patients with H. pylori or the control subjects. A decrease in the acidic mucin content after eradication of H. pylori was commonly observed in all the control subjects. Our investigation raises the possibility that the gastric mucosae of RA patients have resistance against H. pylori infection. And the analysis of the composition in the gastric luminal mucin may be a very useful tool for the evaluation of gastric homeostasis in RA patients.

Immune-mediated alteration in gut physiology and its role in host defence in nematode infection

Activation of the mucosal immune system of the gastrointestinal tract in nematode infection results in altered intestinal physiology, which includes changes in intestinal motility and mucus production. These changes are considered to be under direct immunological control rather than a non-specific consequence of the inflammatory reaction to the infective agent. However, little is known about the immunological basis for the changes in intestinal physiology accompanying nematode infection, or the precise role of these changes in host defence, which remains an important area to explore. In this review we describe the mechanisms by which the immune response to nematode infection influences the changes in two major cells of intestinal physiology, namely smooth muscle and goblet cells, and how these changes in intestinal physiology contribute to the host defence. Data clearly demonstrate that the T helper (Th) 2 type immune response generated by nematode infection plays an important role in the development of infection-induced intestinal muscle hypercontractility and goblet cell hyperplasia and that these immune-mediated changes in intestinal physiology are associated with worm expulsion. These observations strongly suggest that intestinal muscle contractility, goblet cell hyperplasia and worm expulsion share a common immunological basis and may be causally related. These data not only provide insights into host defence in nematode infection in the context of muscle function and goblet cell response, but also have broad implications in elucidating the pathophysiology of a wide range of gastrointestinal disorders associated with altered gut physiology.

Mechanisms of natural tolerance in the intestine: implications for inflammatory bowel disease

Tolerance, the regulated inability to respond to a specific immunologic stimulant, is a physiological event important to normal immune function. Just as loss of tolerance to self-proteins results in autoimmune diseases, we assert that loss of tolerance to commensal flora in the intestinal lumen leads to inflammatory bowel disease (IBD). Mechanisms through which the mucosal immune system establishes and remains hyporesponsive toward the presence of food proteins and commensal flora, which we define as natural tolerance, are discussed. In addition to the contributions by commensal flora, the innate host defense and the adaptive immune systems promote natural tolerance to sustain normal mucosal homeostasis. Understanding the molecular and cellular events that mediate natural tolerance will lead to more advanced insights into IBD pathogenesis and improved therapeutic options.

Colonic expression of MUC2, MUC5AC, and TFF1 in inflammatory bowel disease in children

BACKGROUND

The quantity and quality of mucins are affected in inflammatory bowel disease (IBD) both because of a reduction in the number of goblet cells and a decrease in the number of sugar residues per oligosaccharide side chain. Alteration in the types of mucins and aberrant location may contribute to the underlying pathology by affecting the mucus barrier function or may instead be a response to inflammation. The authors used the periodic acid-Schiff/Alcian blue stain to distinguish neutral and acidic mucins, and used specific antibodies to the mature goblet cell mucin MUC2, MUC2 core antigen, foveolar cell mucin MUC5AC, and gastric trefoil factor (TFF1), to characterize their presence and distribution in colonic tissue sections from patients with IBD.

RESULTS

Both core and mature MUC2 were expressed in all colonic goblet cells from patients with ulcerative colitis (UC) and Crohn disease and from healthy controls. MUC5AC and TFF1, which are not normally expressed by colonic tissue, also were expressed in scattered goblet cells, coexpressing with MUC2. In areas of goblet cell depletion, MUC2 was present in cytoplasmic granules of flattened, cuboidal, nongoblet-cell-like surface cells. The staining was more intense and homogenous with the MUC2 core antibody, suggesting expression of relatively immature mucin. Some of these cells also coexpressed MUC5AC but to a lesser extent. These findings are not unique to IBD but were also found in other types of intestinal inflammation.

CONCLUSION

The study confirms earlier observations that MUC2 is the major colonic mucin in IBD. It appears in two forms: mature MUC2 in goblet cells and immature MUC2 especially in secretory granules of cells that are not phenotypically goblet cells. MUC5AC and TFF1 expression in goblet cells is common in IBD and other inflammatory conditions of the colon. These changes may represent a nonspecific repair function of the colon cells to compensate for damage to barrier function.

Rat small intestinal goblet cell kinetics in the process of restitution of surface epithelium subjected to ischemia-reperfusion injury

Repair of superficial damage to gastrointestinal mucosa occurs by a process called restitution. Goblet cells reside throughout the length of the intestine and are responsible for the production of mucus. However, a kinetic analysis of goblet cell dynamics of small intestine in restitution has hitherto not been reported. The aim of the present study was to investigate the role of goblet cells in the process of restitution of rat small intestine subjected to ischemia and ischemia-reperfusion injury, and therefore intestinal epithelium from rats subjected to both ischemia and ischemia-reperfusion was studied. Detachment of enterocytes was observed after 5-min of reperfusion. After 20-30 minutes of reperfusion, the denuded villous tips were covered with goblet cells. Within 75 min of reperfusion the epithelium restitution was complete. On the other hand, restitution was not observed in ischemia group. These data suggest that goblet cells may play an important role in restitution after ischemia-reperfusion injury.

Sd(a)-antigen-like structures carried on core 3 are prominent features of glycans from the mucin of normal human descending colon

This paper describes structural characterization by NMR, MS and degradative studies of mucin glycans from normal human descending colon obtained freshly at autopsy. The saccharides were mainly based on core 3 (GlcNAcbeta1-3GalNAc). Among the terminal saccharide determinants Sd(a)/Cad-antigen-like structures were prominent, and Lewis x, sialyl Lewis x and sulphated Lewis x were found as minor components, whereas blood group H and A antigenic determinants were absent. The saccharides were markedly different from those of mucins from colon cancers or colon cancer cell lines analysed so far, in which cores 1 and 2 are prominent features, and in which various other terminal determinants have been found, but not Sd(a)/Cad.

Altered mucin expression in the gastrointestinal tract: a review

Early studies of changes in mucin expression in disorders of the gastrointestinal tract focused on alterations in the carbohydrate chain. This review briefly considers the various mechanisms by which such alterations may come about: (a) normal variation, (b) sialic acid alterations, (c) defective assembly of carbohydrate side-chains, (d) changed expression of core proteins and (e) epithelial metaplasia. The availability of monoclonal antibodies to mucin core proteins adds a new dimension to mucin histochemistry. It is now possible to offer explanations for traditional mucin histochemical findings on the basis of lineage-specific patterns of mucin core protein expression. Changes in core protein expression are described in inflammatory, metaplastic and neoplastic disorders of the gastrointestinal tract. The possibility that mucin change could be important in the aetiology of some diseases such as ulcerative colitis and H. pylori gastritis is considered. It is more probable, however, that changes in mucin expression are secondary to reprogramming of cellular differentiation and altered cell turnover. As such they may serve as markers to explain pathogenesis and provide novel diagnostic and prognostic information.

Recent advances in inflammatory bowel disease

The last decade has seen tremendous advances in our knowledge, which has led to genuine improvements in our understanding of the pathogenesis and management of inflammatory bowel disease (IBD). The combined power of cellular and molecular biology has begun to unveil the enigmas of IBD, and, consequently, substantial gains have been made in the treatment of IBD. Refinements in drug formulation have provided the ability to target distinct sites of delivery, while enhancing the safety and efficacy of older agents. Simultaneous progress in biotechnology has fostered the development of new agents that strategically target pivotal processes in disease pathogenesis. This article addresses our current understanding of the pathogenesis of IBD, including the latest developments in animal models and covers agents currently used in the treatment of IBD as well as emerging therapies.

Stat6 dependent goblet cell hyperplasia during intestinal nematode infection

To identify the role of signal transducer and activator of transcription factor 6 (Stat6) in the development of intestinal goblet cell hyperplasia during nematode infection, we compared the number of goblet cells in Stat6 deficient (Stat6 -/-) mice with that generated in wild-type (Stat6 +/+) mice in Trichinella spiralis infection. The number of goblet cells significantly increased with infection in wild-type mice. However, Stat6 -/- failed to generate infection-induced goblet cell hyperplasia and a significantly lower number of goblet cells was observed in Stat6 -/- mice on days 14 and 21 postinfection compared to Stat6 +/+ mice. In addition to suppressed goblet cell numbers, Stat6 -/- mice exhibited severe impairment in their ability to produce IL-4 and IL-13 and to expel the parasites from the gut. Our study clearly shows an essential role of Stat6 in intestinal goblet cell hyperplasia which accompanies this infection. We postulate that Th2 cytokines regulate the development of goblet cell hyperplasia in gut during nematode infection via Stat6 activation and that the increased number of goblet cells plays an important role in host protective immunity against the infection.

A new strategy for evaluation of the eradication treatment of Helicobacter pylori: validation of the analysis of mucin composition in human gastric juice

The change in the mucin composition of human gastric juice has been investigated in patients before and after the eradication of the Helicobacter pylori (H. pylori) infection. We confirmed the successful eradication of H. pylori in all 17 patients. The gastric luminal mucins were divided into three fractions by ion-exchange chromatography using a discontinuous salt gradient with three salt steps. Although there was a significant variation in the proportion of the mucin content in each fraction among the individual patients, a decrease in the acidic mucin content after the eradication of H. pylori was commonly observed in all the patients. These results indicate that the mucin compositional analysis in the gastric luminal mucin may be a very useful tool for the assessment of H. pylori eradication.

Gastrointestinal tract antigenic profile of cotton-top tamarin, Saguinus oedipus, is similar to that of humans with inflammatory bowel disease

As an animal model for human inflammatory bowel disease and colorectal cancer, the cotton-top tamarin remains controversial. Demonstration of antigenic similarity to the human would enhance its validity. Using colonic extracts and washings, we compared binding of seven monoclonal antibodies reactive with bowel and cancer antigens in both tamarins and humans with inflammatory bowel disease. Additionally, telomerase activity was tested for. Expression of a mucin antigen specific to human cancer was increased in tamarin colonic washings as well as aminoproteoglycans and EGFR in tamarin extracts, as compared to those of humans with inflammatory bowel disease (P < 0.005). An adenoma-associated antigen and k-ras p21 protein were negative in the tamarin. A trend to greater telomerase activity exists in tamarins. The antigenic similarity validates this model for human inflammatory bowel disease and colorectal cancer. A trend to increased telomerase activity in tamarins is consistent with the greater predisposition to cancer in these animals.

Cloning of a mucin-desulfating sulfatase gene from Prevotella strain RS2 and its expression using a Bacteroides recombinant system

A gene encoding the mucin-desulfating sulfatase in Prevotella strain RS2 has been cloned, sequenced, and expressed in an active form. A 600-bp PCR product generated using primers designed from amino acid sequence data was used to isolate a 5,058-bp genomic DNA fragment containing the mucin-desulfating sulfatase gene. A 1,551-bp open reading frame encoding the sulfatase proprotein was identified, and the deduced 517-amino-acid protein minus its signal sequence corresponded well with the published mass of 58 kDa estimated by denaturing gel electrophoresis. The sulfatase sequence showed homology to aryl- and nonarylsulfatases with different substrate specificities from the sulfatases of other organisms. No sulfatase activity could be detected when the sulfatase gene was cloned into Escherichia coli expression vectors. However, cloning the gene into a Bacteroides expression vector did produce active sulfatase. This is the first mucin-desulfating sulfatase to be sequenced and expressed. A second open reading frame (1,257 bp) was identified immediately upstream from the sulfatase gene, coding in the opposite direction. Its sequence has close homology to iron-sulfur proteins that posttranslationally modify other sulfatases. By analogy, this protein is predicted to catalyze the modification of a serine group to a formylglycine group at the active center of the mucin-desulfating sulfatase, which is necessary for enzymatic activity.

Prostaglandin E(2) stimulates rat and human colonic mucin exocytosis via the EP(4) receptor

BACKGROUND & AIMS

Mucins form an integral part of innate host defenses against intestinal pathogens and irritants. However, the mechanisms whereby mucin secretion is regulated during inflammation are poorly understood. Because prostaglandin E(2) (PGE(2)) is prominent during intestinal inflammation, we investigated its receptor-signaling pathway coupled to mucin exocytosis in the colonic epithelial cell line LS174T and rat colon.

METHODS

Reverse-transcription polymerase chain reaction (RT-PCR) and [(3)H]PGE(2) binding assays were used to identify the PGE(2) receptors (EP). Intracellular cyclic adenosine monophosphate ([cAMP](i)) was quantified by enzyme immunoassay. Mucins were metabolically labeled with [(3)H]glucosamine, and mucin secretion was quantified by Sepharose 4B column chromatography, immunoblot analysis, and cesium chloride density gradient centrifugation.

RESULTS

RT-PCR and DNA sequence analysis identified EP(2), EP(3), and EP(4) receptors. Mucin secretion and [cAMP](i) production by LS174T cells were stimulated dose-dependently by PGE(2), the EP(4)-receptor agonist 1-OH-PGE(1), and the EP(3)/EP(4) agonist M&B28767 and were inhibited with the adenylate cyclase inhibitor SQ22536. The EP(1), EP(2), and EP(3)/EP(1)-receptor agonists iloprost, butaprost, and sulprostone, respectively, had no effect. Similar results were obtained in rat colonic loop studies confirming that the EP(4) receptor is linked to mucin exocytosis in vivo. [(3)H]PGE(2) binding to cell membranes identified a high-affinity binding site that was competitively inhibited by M&B28767 (EP(3)/EP(4)) > 1-OH-PGE(1) (EP(4)) > sulprostone (EP(3)/EP(1)) > butaprost (EP(2)).

CONCLUSIONS

PGE(2) coupling to the EP(4) receptor stimulates [cAMP](i)-dependent mucin exocytosis.

Intestinal trefoil factor binds to intestinal epithelial cells and induces nitric oxide production: priming and enhancing effects of mucin

Intestinal trefoil factor (ITF or TFF3), NO and epithelium-associated mucin have important roles in sustaining mucosal integrity in the gastrointestinal tract. In the present study we examined ITF-binding molecules on IEC-18 cells (an intestinal epithelial cell line) with the use of flow cytometry and localized these molecules on the cell surface by confocal microscopy. Furthermore, we studied the interaction of mucin and ITF and their co-operative effect on NO production by the epithelium. Stimulation of cells with mucin (5 mg/ml) for 90 min resulted in a 5-fold increase in ITF binding. Treatment of IEC-18 cells with actinomycin D or cycloheximide attenuated mucin-enhanced ITF binding. Ligand blot analysis confirmed the induction of ITF-binding protein in IEC-18 cells by mucin. These results indicate that transcriptional and translational mechanisms are involved in the effect of mucin. Treatment with ITF overnight resulted in a low level of nitrite production by the cells, a 5-fold increase over control, in a concentration-dependent manner. ITF-induced NO production was attenuated by 1400W, a selective type II nitric oxide synthase (NOS2) inhibitor. By immunoblotting we found that NOS2 was up-regulated by ITF treatment. Priming IEC-18 cells with mucin for 90 min enhanced the effect of ITF on NO production, suggesting that the up-regulation of ITF-binding molecules by mucin might be physiologically relevant. Taken together, these observations indicate (1) that ITF-binding molecules that are up-regulated by mucin exist on the intestinal epithelial surface, and (2) that ITF modulates epithelial NO production via the NOS2 pathway, which is enhanced by mucin.