Altered mucin expression in the gastrointestinal tract: a review

Molecular studies of phages-Klebsiella pneumoniae in mucoid environment: innovative use of mucolytic agents prior to the administration of lytic phages

Mucins are important glycoproteins that form a protective layer throughout the gastrointestinal and respiratory tracts. There is scientific evidence of increase in phage-resistance in the presence of mucin for some bacterial pathogens. Manipulation in mucin composition may ultimately influence the effectiveness of phage therapy. In this work, two clinical strains of K. pneumoniae (K3574 and K3325), were exposed to the lytic bacteriophage vB_KpnS-VAC35 in the presence and absence of mucin on a long-term co-evolution assay, in an attempt to mimic in vitro the exposure to mucins that bacteria and their phages face in vivo. Enumerations of the bacterial and phage counts at regular time intervals were conducted, and extraction of the genomic DNA of co-evolved bacteria to the phage, the mucin and both was performed. We determined the frequency of phage-resistant mutants in the presence and absence of mucin and including a mucolytic agent (N-acetyl L-cysteine, NAC), and sequenced them using Nanopore. We phenotypically demonstrated that the presence of mucin induces the emergence of bacterial resistance against lytic phages, effectively decreased in the presence of NAC. In addition, the genomic analysis revealed some of the genes relevant to the development of phage resistance in long-term co-evolution, with a special focus on the mucoid environment. Genes involved in the metabolism of carbohydrates were mutated in the presence of mucin. In conclusion, the use of mucolytic agents prior to the administration of lytic phages could be an interesting therapeutic option when addressing K. pneumoniae infections in environments where mucin is overproduced.

The Role of Membrane-Tethered Mucins in Axial Epithelial Adhesion in Controlled Normal Stress Environments

The collective adhesive behavior of epithelial cell layers mediated by complex macromolecular fluid environments plays a vital role in many biological processes. Mucins, a family of highly glycosylated proteins, are known to lubricate cell-on-cell contacts in the shear direction. However, the role of mucins mediating axial epithelial adhesion in the direction perpendicular to the plane of the cell sheet has received less attention. This article subjects cell-on-cell layers of live ocular epithelia that express mucins on their apical surfaces to compression/decompression cycles and tensile loading using a customized instrument. In addition to providing compressive moduli of native cell-on-cell layers, it is found that the mucin layer between the epithelia acts as a soft cushion between the epithelial cell layers. Decompression experiments reveal mucin layers act as soft, nonlinear springs in the axial direction. The cell-on-cell layers withstand decompression before fracturing by a cohesive failure within the mucin layer. When mucin deficiency is induced via a protease treatment, it is found that the axial adhesion between the cell layers is increased. The findings which correlate changes in biological factors with changes in mechanical properties might be of interest to challenges in ophthalmology, vision care, and mucus research.

O-acetylesterase activity of Bifidobacterium bifidum sialidase facilities the liberation of sialic acid and encourages the proliferation of sialic acid scavenging Bifidobacterium breve

Bifidobacterium bifidum possesses two extracellular sialidases (SiaBb1 and SiaBb2) that release free sialic acid from mucin sialoglycans, which can be utilized via cross-feeding by Bifidobacterium breve that, otherwise, is prevented from utilizing this nutrient source. Modification of sialic acids with O-acetyl esters is known to protect mucin glycans from degradation by bacterial sialidases. Compared to SiaBb2, SiaBb1 has an additional O-acetylesterase (Est) domain. We aimed to elucidate the role of the SiaBb1 Est domain from B. bifidum in sialic acid cross-feeding within Bifidobacterium. Pre-treatment of mucin secreted from bovine submaxillary glands (BSM) using His₆ -tagged-Est and -SiaBb2 released a higher amount of sialic acid compared to the pre-treatment by His₆ -SiaBb2. Growth of B. breve increased with an increase in nanE expression when supplemented with both His₆ -Est- and His₆ -SiaBb2-treated BSM. These results indicate that the esterase activity of the SiaBb1 Est domain enhances the efficiency of SiaBb2 to cleave sialic acid from mucin. This free sialic acid can be utilized by coexisting sialic acid scavenging B. breve via cross-feeding. Here, we provide the molecular mechanism underlying the unique sialoglycan degradation property of B. bifidum which is mediated by the complementary activities of SiaBb1 and SiaBb2 in the context of sialic acid cross-feeding.

Expression of Mucin1 in saliva in oral squamous cell carcinoma and oral potentially malignant disorders (case control study)

OBJECTIVES

Overexpression of mucin1 is found in head and neck squamous cell carcinoma tissues compared with adjacent non-neoplastic tissues and higher levels are associated with metastasis and invasion. The expression level of mucin1 in saliva of normal individuals, oral potentially malignant disorders and oral squamous cell carcinoma patients and its correlation to clinical and histological variables was evaluated.

SUBJECTS AND METHODS

Forty oral potentially malignant disorders, 40 oral squamous cell carcinoma subjects, and 20 age matched-controls were included. Stimulated salivary samples were collected from all participants, and mucin1 expression was measured by real-time PCR.

RESULTS

Mucin1 expression in saliva was significantly elevated in oral potentially malignant disorders when compared with controls. Similarly, mucin1 expression was significantly elevated in oral squamous cell carcinoma group when compared with oral potentially malignant disorders and controls. Mucin1 expression in OSCC patient showed significant positive correlations with T classification and distant Metastasis. Mucin1 expression in oral potentially malignant disorders patients showed significant positive correlations with degree of dysplasia.

CONCLUSIONS

The expression level of mucin1 in saliva might be a potential biomarker for diagnosing oral potentially malignant disorders and oral squamous cell carcinoma.

The morphological changes of the colonic goblet cells and mucin profile in oncohematological patients under Epirubicin-based chemotherapy

Changes in the lining of the small intestine following chemotherapy have been extensively studied, although also occurs in the large intestine. The aim of this study was to assess the consequences of Epirubicin-based therapy on goblet cells (GCs) and mucus production on colonic mucosa, immediately and after short-time of chemotherapy administration to oncohematological patients, by clinical and histopathological analysis. We assessed the mucus production, composition, and distribution by Alcian Blue (pH 2.5)–Periodic Acid–Schiff (PAS) staining, alongside with the immunoexpression of mucin (MUC)2, MUC4 and inflammatory markers in a series of oncohematological patients, immediately and after short-time of Epirubicin-based chemotherapy cumulative therapy cessation. We showed that GCs number decrease slightly at 48 hours, while mucous secretion became mixed (with a few neutral) after three weeks. Overall, the secretion was increased immediately after the Epirubicin administration, due to the activation of inflammatory pathways, assessed by increased immunostaining of tumor necrosis factor-alpha (TNF-α) at 48 hours. The MUC2 and MUC4 showed a decreased immunoexpression at 48 hours after the Epirubicin administration compared to controls and partially restored three weeks after the cessation. Overall, it is highly plausible that all these key players revolve around the chemotherapy-induced mucositis in oncohematological patients and highlights the morphofunctional particularities of the GCs, which further modulates the clinical outcome of the patient.

Characterizing Phage-Host Interactions in a Simplified Human Intestinal Barrier Model

An intestinal epithelium model able to produce mucus was developed to provide an environment suitable for testing the therapeutic activity of gut bacteriophages. We show that Enterococcus faecalis adheres more effectively in the presence of mucus, can invade the intestinal epithelia and is able to translocate after damaging tight junctions. Furthermore, Enterococcus phage vB_EfaM_A2 (a member of Herelleviridae that possesses virion associated immunoglobin domains) was found to translocate through the epithelium in the presence and absence of its host bacteria. Phage A2 protected eukaryotic cells by reducing mortality and maintaining the structure of the cell layer structure. We suggest the mammalian cell model utilized within this study as an adaptable in vitro model that can be employed to enable a better understanding of phage-bacteria interactions and the protective impact of phage therapy relating to the intestinal epithelium.

Djulis (Chenopodium Formosanum) Prevents Colon Carcinogenesis via Regulating Antioxidative and Apoptotic Pathways in Rats

Djulis is a cereal crop rich in polyphenols and dietary fiber that may have nutraceutical activity to prevent colon cancer. This study was designed to examine the preventive effect of djulis on colon carcinogenesis in rats treated with 1,2-dimethylhydrazine (DMH). Rats were fed different AIN-93G-based diets: groups N and DMH were fed AIN-93G diet and groups LD, MD, and HD were fed AIN-93G diet containing 5, 10, and 20% djulis, respectively. All rats except for group N were injected with DMH to induce colon carcinogenesis. After 10 weeks, rats were sacrificed and colon and liver tissues were collected for analysis. The results showed that djulis-treated rats had significantly lower numbers of colonic preneoplastic lesions, aberrant crypt foci (ACF), sialomucin-producing (SIM)-ACF, and mucin-depleted foci. Djulis treatment increased superoxide dismutase and catalase activities in colon and liver. Djulis also reduced p53, Bcl-2, and proliferating cell nuclear antigen expressions and increased Bax and caspase-9 expressions. Besides, phenolic compounds and flavonoids were found rich in djulis. These results demonstrate the chemopreventive effect of djulis on carcinogen-induced colon carcinogenesis via regulating antioxidative and apoptotic pathways in rats. Djulis may have the potential to be developed as a valuable cereal product for chemoprevention of colon cancer.

[Comparative assessment of the expression of Muc 2, Muc 5AC, and Muc 6 in serrated neoplasms of the colon]

In the course of the serrated pathway of carcinogenesis, there are changes in the expression of mucins with a characteristic immunophenotypic sign, such as a late loss of intestinal differentiation and an increase in gastric differentiation.

OBJECTIVE

To comparatively assess the expression of Muc 2, Muc 5AC, and Muc 6 in hyperplastic polyps (HPs), sessile serrated adenomas (SSAs) and traditional serrated adenomas (TSAs) of the colon for determination of their role in differential diagnosis.

MATERIAL AND METHODS

Sixty-five serrated masses from 52 patients were examined. Among them, there were 26 SSAs, 26 HPs, and 13 TSAs. A histological examination was done using hematoxylin and eosin staining; periodic acid-Schiff reaction in combination with alcian blue, as well as immunohistochemistry with anti-Muc 2, anti-Muc 5AC, and anti-Muc 6 antibodies were used. Genetic testing of the specimens for KRAS and BRAF mutations was also carried out.

RESULTS

All the serrated neoplasms of the colon exhibited a pronounced expression of Muc 2. A marked Muc 6 expression in the dilated crypt bases was found in 76.9% of SSAs, while no reaction was seen in 92.3% of HPs and in 100% of TSAs. SSAs were characterized by an intense Muc 5AC expression in the whole length of the crypts and in the surface epithelium in contrast with HPs and TSAs, where the expression of the marker was focal. Comparison of the response of the markers and the presence of gene mutations identified that the SSAs with BRAF mutation intensely expressed along the length of the crypt for Muc 5AC and Muc 6; and the TSAs with KRAS mutation had a moderate focal Muc 5AC expression in the crypt bases in 100% of cases.

CONCLUSION

For differential diagnosis of the types of serrated adenomas of the colon, it is useful for a pathologist to apply the immunohistochemical markers Muc 2, Muc 5AC, and Muc 6 in his/her practice.

The Role of the Cell Surface Mucin MUC1 as a Barrier to Infection and Regulator of Inflammation

The family of cell surface (cs-) mucins are constitutively expressed at the cell surface by nearly all epithelial cells, beneath the gel-mucin layer. All cs-mucin family members have structural features that enable them to act as a releasable decoy barrier to mucosal pathogens, by providing ligands for pathogen binding and the ability to shed the bound extracellular domain. Due to the towering structure of cs-mucins at the surface, binding of mucosal pathogens can also sterically block binding to underlying cellular receptors. The cytoplasmic tail domain of cs-mucins are capable of initiating signal transduction cascades and due to their conservation across species, may play an important biological role in cellular signaling. MUC1 is one of the most extensively studied of the cs-mucin family. With respect to its physiological function in the mucosal environment, MUC1 has been demonstrated to play a dynamic role in protection of the host from infection by a wide variety of pathogens and to regulate inflammatory responses to infection. This review briefly summarizes the current knowledge and new findings regarding the structural features relating to the function of MUC1, its role as a protective barrier against pathogen invasion and mechanisms by which this cs-mucin regulates inflammation.

Effects of microbial phytase on mucin synthesis, gastric protein hydrolysis, and degradation of phytate along the gastrointestinal tract of growing pigs

An experiment was conducted to test the hypothesis that pigs fed diets supplemented with exogenous phytase reduce mucin synthesis in the small intestine, increase protein hydrolysis in the stomach, increase breakdown of phytate along the gastrointestinal tract, and increase mineral and AA digestibility. A diet based on corn, soybean meal, and canola meal was formulated to meet requirements for growing pigs except for Ca and P, which were lower than requirements. Three additional diets were formulated by adding 750, 1,500, or 3,000 units of phytase (FTU) per kilogram to the basal diet. Eight growing barrows (38.45 ± 3.06 kg) were prepared with a T-cannula in the duodenum and another T-cannula in the distal ileum. Pigs were housed individually and allotted to a replicated 4 × 4 Latin square design with four pigs and four periods in each square. Each period lasted 14 d with the initial 7 d being the adaptation period to the diets. Pigs were fed twice daily in combined amounts equal to 3.2 times the estimated requirement for maintenance energy. Results indicated that the apparent ileal digestibility (AID) and the apparent total tract digestibility (ATTD) of Ca and P increased (linear and quadratic, P ≤ 0.05) as phytase inclusion increased. However, values for AID of Ca and P were not different from values for ATTD of Ca and P, indicating that there is no net absorption of Ca and P in the hindgut. The apparent duodenal digestibility (ADD) of Ca and P was ~30% and 10% to 20%, respectively, indicating some digestion in the stomach of both Ca and P. A quadratic increase (P < 0.05) of the AID of GE was observed with the breakpoint around 1,500 FTU, but there was a negative linear (P ≤ 0.001) effect of dietary phytase on the ATTD of GE. Phytase did not affect mucin synthesis in the small intestine, protein hydrolysis in the stomach, or ileal digestibility of dispensable and indispensable AA. However, degradation of higher phytate esters (IP6 and IP5) into lower phytate esters (IP4 and IP3) and inositol increased as dietary phytase increased, indicating that it is possible to completely degrade dietary phytate if microbial phytase is included by at least 3,000 FTU in the diet. In conclusion, supplementing diets with phytase resulted in increased degradation of phytate and phytate esters and improved digestibility of Ca and P, but phytase did not change intestinal mucin synthesis, gastric protein hydrolysis, or the AID of AA.

Irinotecan induces enterocyte cell death and changes to muc2 and muc4 composition during mucositis in a tumour-bearing DA rat model

Irinotecan-induced mucositis is a major oncological problem. Goblet cells secrete mucus, protecting the intestinal mucosa, with secretion altered during mucositis. The enteric nervous system is involved in regulating gut motility and secretion. The aim of this study was to determine whether enteric neural cells and goblet cells are altered following irinotecan treatment. Tumour-bearing Dark Agouti rats were administered a single dose of 175 mg/kg of irinotecan intraperitoneally and 0.01 mg/kg atropine subcutaneously. Experimental and untreated control rats were killed at times 6, 24, 48, 72, 96 and 120 h after treatment. Jejunum and colon samples were formalin fixed. Haematoxylin and eosin staining, Alcian Blue-PAS staining, and immunohistochemistry with S-100 antibody (neural cell marker) were carried out. Statistical analyses were carried out using Kruskal-Wallis test with Dunns post test, Mann Whitney U test, and nonlinear regression. Total goblet cells decreased at 72 h compared with controls in the colon (p < 0.05). The percentage of cavitated goblet cells decreased compared to all other time points at 120 h in the colon. The number of S-100-positive cells in the submucosal plexus decreased in the colon (p = 0.0046) and in the myenteric plexus of the jejunum and colon (p = 0.0058 and p = 0.0022, respectively), on comparing treated with control. Enteric ganglia in the myenteric plexus of the jejunum decreased at 24 h and 96 h. Irinotecan-induced mucositis is associated with increases in mucus secretion and enteric neural cell change. These changes may contribute to the pathophysiology of mucositis through the dysregulation of neural signalling.

Anti-ulcerogenic effect of the methanol extract of Chasmanthera dependens (Hochst) stem on male Wistar rats

Background Oxidative stress and free radical-mediated processes have been implicated in the pathogenesis of indomethacin-induced gastric ulcer. This study investigated the ability of the methanol extract of Chasmanthera dependens to protect the gastric mucosal from oxidative damage induced by oral administration of indomethacin in rats. Methods The C. dependens stems were chopped into pieces, air-dried, and pulverized into powder. One kilogram of the powder was macerated in 1 L of methanol for 72 h. The mixture was filtered and evaporated using rotatory evaporator to obtain the extract of C. dependens. Adult male rats were divided into eight groups of six animals per group and were pretreated orally with the methanol extract of C. dependens (200, 400, and 800 mg/kg) or cimetidine (CIM), a standard drug (50 mg/kg), for 7 days. Gastric ulcer was induced orally with indomethacin. Ulcerogenic parameters, oxidative stress indices, and histopathological examination of the stomach were assessed to monitor the gastroprotective potential of C. dependens stem. Results Indomethacin caused severe gastric mucosa damage and significant reduction in the gastric mucosa antioxidant system with concomitant increase in the level of lipid peroxidation. Pretreatment with the methanol extract of C. dependens or CIM significantly reduced the formation of ulcer at the different doses administered. Similarly, pretreatments with the extract or CIM improved the antioxidant system, decreased acid output, lipid peroxidation, and improved the architecture of the gastric mucosa in ulcerated rats. Conclusions The results show the gastroprotective effect of the methanolic extract of C. dependens, which may be attributed to its antioxidant properties.

Th9 Cells: Probable players in ulcerative colitis pathogenesis

T lymphocytes represent an important part of adaptive immune system undertaking different functions to regulate immune responses. CD4+ T cells are the most important activator cells in inflammatory conditions. Depending on the type of induced cells and inflamed sites, expression and activity of different subtypes of helper T cells are changed. Recent studies have confirmed the existence of a new subset of helper T lymphocytes called Th9. Naive T cells can differentiate into Th9 subtypes if they are exposed simultaneously by interleukin (IL) 4 and transforming growth factor β and also secondary activation of a complicated network of transcription factors such as interferon regulatory factor 4 (IRF4) and Smads which are essential for adequate induction of this phenotype. Th9 cells specifically produce interleukin 9 and their probable roles in promoting intestinal inflammation are being investigated in human subjects and experimental models of ulcerative colitis (UC). Recently, infiltration of Th9 cells, overexpression of IL-9, and certain genes associated with Th9 differentiation have been demonstrated in inflammatory microenvironment of UC. Intestinal oversecretion of IL-9 protein is likely to break down epithelial barriers and compromise tolerance to certain commensal microorganisms which leads to inflammation. Th9 pathogenicity has not yet been adequately explored in UC and they are far from being considered as inflammatory cells in this milieu, therefore precise understanding the role of these newly identified cells in particular their potential role in gut pathogenesis may enable us to develop novel therapeutic approaches for inflammatory bowel disease. So, this article tries to discuss the latest knowledge on the above-mentioned field.

Pathogenesis of Inflammatory Bowel Disease and Recent Advances in Biologic Therapies

Inflammatory bowel disease (IBD) is a chronic intestinal inflammatory disorder with an unknown etiology. IBD is composed of two different disease entities: Crohn's disease (CD) and ulcerative colitis (UC). IBD has been thought to be idiopathic but has two main attributable causes that include genetic and environmental factors. The gastrointestinal tract in which this disease occurs is central to the immune system, and the innate and the adaptive immune systems are balanced in complex interactions with intestinal microbes under homeostatic conditions. However, in IBD, this homeostasis is disrupted and uncontrolled intestinal inflammation is perpetuated. Recently, the pathogenesis of IBD has become better understood owing to advances in genetic and immunologic technology. Moreover, new therapeutic strategies are now being implemented that accurately target the pathogenesis of IBD. Beyond conventional immunesuppressive therapy, the development of biological agents that target specific disease mechanisms has resulted in more frequent and deeper remission in IBD patients, with mucosal healing as a treatment goal of therapy. Future novel biologics should overcome the limitations of current therapies and ensure that individual patients can be treated with optimal drugs that are safe and precisely target IBD.

MUC1, MUC2, MUC5AC, and MUC6 in colorectal cancer: expression profiles and clinical significance

Mucin glycoprotein expression can be altered during the carcinogenic process. The impact on the prognosis of patients with colorectal cancer (CRC) is controversial. We analyzed tumors from 381 patients for MUC1, MUC2, MUC5AC, and MUC6 expression by immunohistochemical staining, using tissue microarrays. Progression-free and cancer-specific survival were determined using the Kaplan-Meier method. Expression of intestinal mucin MUC2 was lost in 85 (23 %) CRCs, and patients with MUC6-negative tumors showed shorter progression-free survival (PFS, p = 0.043). Gastric mucins MUC5AC and MUC6 showed high (>50 %) aberrant expression in 28 (8 %) and 9 (2 %) cases, respectively. High expression of MUC5AC was associated with longer PFS (p = 0.055). High expression of MUC6 was associated with 100 % PFS (p = 0.024) and longer cancer-specific survival (CSS, p = 0.043). MUC1 was expressed in 238 (64 %) tumors and had no impact on outcome. When analysis was restricted to stages II and III, loss of MUC2 was associated with adverse outcome. Overexpression of both MUC5AC and MUC6 significantly predicted favorable PFS and CSS. In conclusion, loss of MUC2 expression proved to be a predictor of adverse outcome, while the gain of aberrant expression of MUC5AC and particularly of MUC6 was associated with favorable outcome in CRC, notably in intermediate stages II and III.

Preventative Effects of Sodium Alginate on Indomethacin-induced Small-intestinal Injury in Mice

Recent advances in diagnostic technologies have revealed that nonsteroidal anti-inflammatory drugs (NSAIDs) can cause serious mucosal injury in the upper and lower gastrointestinal tract (including the small intestine). A drug to treat NSAID-induced small-intestinal injury (SII) is lacking. Sodium alginate is a soluble dietary fiber extracted from brown seaweed and its solution has been used as a hemostatic agent to treat gastrointestinal bleeding due to gastric ulcers. Whether sodium alginate has therapeutic effects on NSAID-induced SII and its mechanism of action are not known. Here, we investigated if administration of two forms (high-molecular-weight (HMW) and low-molecular-weight (LMW)) of sodium alginate could ameliorate indomethacin-induced SII. Pretreatment with HMW sodium alginate or LMW sodium alginate before indomethacin administration improved ulceration and the resultant intestinal shortening was associated with reduced histological severity of mucosal injury and ameliorated mRNA expression of inflammation-related molecules in the small intestine. We found that mRNAs of secretory Muc2 and membrane-associated Muc1, Muc3 and Muc4 were expressed in the small intestine. mRNA expression of Muc1-4 was increased in indomethacin-induced SII, and these increases were prevented by sodium alginate. Thus, administration of sodium alginate could be a therapeutic approach to prevent indomethacin-induced SII.

Mitochondrial dysfunction in inflammatory bowel disease

Inflammatory Bowel Disease (IBD) represents a group of idiopathic disorders characterized by chronic or recurring inflammation of the gastrointestinal tract. While the exact etiology of disease is unknown, IBD is recognized to be a complex, multifactorial disease that results from an intricate interplay of genetic predisposition, an altered immune response, changes in the intestinal microbiota, and environmental factors. Together, these contribute to a destruction of the intestinal epithelial barrier, increased gut permeability, and an influx of immune cells. Given that most cellular functions as well as maintenance of the epithelial barrier is energy-dependent, it is logical to assume that mitochondrial dysfunction may play a key role in both the onset and recurrence of disease. Indeed several studies have demonstrated evidence of mitochondrial stress and alterations in mitochondrial function within the intestinal epithelium of patients with IBD and mice undergoing experimental colitis. Although the hallmarks of mitochondrial dysfunction, including oxidative stress and impaired ATP production are known to be evident in the intestines of patients with IBD, it is as yet unclear whether these processes occur as a cause of consequence of disease. We provide a current review of mitochondrial function in the setting of intestinal inflammation during IBD.

Mammalian gut immunity

The mammalian intestinal tract is the largest immune organ in the body and comprises cells from non-hemopoietic (epithelia, Paneth cells, goblet cells) and hemopoietic (macrophages, dendritic cells, T-cells) origin, and is also a dwelling for trillions of microbes collectively known as the microbiota. The homeostasis of this large microbial biomass is prerequisite to maintain host health by maximizing beneficial symbiotic relationships and minimizing the risks of living in such close proximity. Both microbiota and host immune system communicate with each other to mutually maintain homeostasis in what could be called a "love-hate relationship." Further, the host innate and adaptive immune arms of the immune system cooperate and compensate each other to maintain the equilibrium of a highly complex gut ecosystem in a stable and stringent fashion. Any imbalance due to innate or adaptive immune deficiency or aberrant immune response may lead to dysbiosis and low-grade to robust gut inflammation, finally resulting in metabolic diseases.

Increasing the α 2, 6 sialylation of glycoproteins may contribute to metastatic spread and therapeutic resistance in colorectal cancer

Abnormal glycosylation due to dysregulated glycosyltransferases and glycosidases is a key phenomenon of many malignancies, including colorectal cancer (CRC). In particular, increased ST6 Gal I (β-galactoside α 2, 6 sialyltransferase) and subsequently elevated levels of cell-surface α 2, 6-linked sialic acids have been associated with metastasis and therapeutic failure in CRC. As many CRC patients experience metastasis to the liver or lung and fail to respond to curative therapies, intensive research efforts have sought to identify the molecular changes underlying CRC metastasis. ST6 Gal I has been shown to facilitate CRC metastasis, and we believe that additional investigations into the involvement of ST6 Gal I in CRC could facilitate the development of new diagnostic and therapeutic targets. This review summarizes how ST6 Gal I has been implicated in the altered expression of sialylated glycoproteins, which have been linked to CRC metastasis, radioresistance, and chemoresistance.

Recent advances in inflammatory bowel disease: mucosal immune cells in intestinal inflammation

The intestine and its immune system have evolved to meet the extraordinary task of maintaining tolerance to the largest, most complex and diverse microbial commensal habitat, while meticulously attacking and containing even minute numbers of occasionally incoming pathogens. While our understanding is still far from complete, recent studies have provided exciting novel insights into the complex interplay of the many distinct intestinal immune cell types as well as the discovery of entirely new cell subsets. These studies have also revealed how proper development and function of the intestinal immune system is dependent on its specific microbiota, which appears to have evolutionarily co-evolved. Here we review key immune cells that maintain intestinal homeostasis and, conversely, describe how altered function and imbalances may lead to inflammatory bowel disease (IBD). We highlight the latest developments within this field, covering the major players in IBD including intestinal epithelial cells, macrophages, dendritic cells, adaptive immune cells, and the newly discovered innate lymphoid cells, which appear of characteristic importance for immune function at mucosal surfaces. We set these mucosal immune pathways in the functional context of IBD risk genes where such insight is available. Moreover, we frame our discussion of fundamental biological pathways that have been elucidated in model systems in the context of results from clinical trials in IBD that targeted key mediators secreted by these cells, as an attempt of 'functional' appraisal of these pathways in human disease.

RNA in situ hybridization in whole mount embryos and cell histology adapted for marine elasmobranchs

Marine elasmobranchs are valued animal models for biomedical and genomic studies as they are the most primitive vertebrates to have adaptive immunity and have unique mechanisms for osmoregulation. As the most primitive living jawed-vertebrates with paired appendages, elasmobranchs are an evolutionarily important model, especially for studies in evolution and development. Marine elasmobranchs have also been used to study aquatic toxicology and stress physiology in relationship to climate change. Thus, development and adaptation of methodologies is needed to facilitate and expand the use of these primitive vertebrates to multiple biological disciplines. Here I present the successful adaptation of RNA whole mount in situ hybridization and histological techniques to study gene expression and cell histology in elasmobranchs. Monitoring gene expression is a hallmark tool of developmental biologists, and is widely used to investigate developmental processes. RNA whole mount in situ hybridization allows for the visualization and localization of specific gene transcripts in tissues of the developing embryo. The expression pattern of a gene's message can provide insight into what developmental processes and cell fate decisions a gene may control. By comparing the expression pattern of a gene at different developmental stages, insight can be gained into how the role of a gene changes during development. While whole mount in situ's provides a means to localize gene expression to tissue, histological techniques allow for the identification of differentiated cell types and tissues. Histological stains have varied functions. General stains are used to highlight cell morphology, for example hematoxylin and eosin for general staining of nuclei and cytoplasm, respectively. Other stains can highlight specific cell types. For example, the alcian blue stain reported in this paper is a widely used cationic stain to identify mucosaccharides. Staining of the digestive tract with alcian blue can identify the distribution of goblet cells that produce mucosaccharides. Variations in mucosaccharide constituents on short peptides distinguish goblet cells by function within the digestive tract. By using RNA whole mount in situ's and histochemical methods concurrently, cell fate decisions can be linked to gene-specific expression. Although RNA in situ's and histochemistry are widely used by researchers, their adaptation and use in marine elasmobranchs have met limited and varied success. Here I present protocols developed for elasmobranchs and used on a regular basis in my laboratory. Although further modification of the RNA in situ's hybridization method may be needed to adapt to different species, the protocols described here provide a strong starting point for researchers wanting to adapt the use of marine elasmobranchs to their scientific inquiries.

Epithelial tyrosine phosphatase SHP-2 protects against intestinal inflammation in mice

Polymorphisms of PTPN11 encoding SHP-2 are biomarkers for ulcerative colitis (UC) susceptibility. However, their functional relevance is unknown. We thus investigated the role of epithelial SHP-2 in the control of intestinal homeostasis. Mice with an intestinal epithelial cell-specific SHP-2 deletion (SHP-2(IEC-KO) mice) were generated. Control and SHP-2(IEC-KO) mice were monitored for clinical symptoms and sacrificed for histological staining and Western blot analyses. Cytokines and chemokines, as well as intestinal permeability, were quantified. SHP-2 mRNA expression was evaluated in control and UC patients. SHP-2(IEC-KO) mice showed growth retardation compared to control littermates and rapidly developed severe colitis. Colon architecture was markedly altered with infiltration of immune cells, crypt abscesses, neutrophil accumulation, and reduced goblet cell numbers. Decreased expression of claudins was associated with enhanced intestinal permeability in mutant SHP-2(IEC-KO) mice. Inflammatory transcription factors Stat3 and NF-κB were hyperactivated early in the mutant colonic epithelium. Levels of several epithelial chemokines and cytokines were markedly enhanced in SHP-2(IEC-KO) mice. Of note, antibiotic treatment remarkably impaired the development of colitis in SHP-2(IEC-KO) mice. Finally, SHP-2 mRNA levels were significantly reduced in intestinal biopsy specimens from UC patients. Our results establish intestinal epithelial SHP-2 as a critical determinant for prevention of gut inflammation.

[Pathology and pathobiology of the gastric carcinoma]

Recent epidemiological studies in Serbia revealed that gastric carcinoma is the third and the fifth main cause of cancer morbidity in men and women, respectively. Despite the declining incidence of gastric cancer, it remains the second most common cause of cancer-related deaths as it is worldwide. A well-defined carcinogenic inflammation-metaplasia-dysplasia-cancer sequence typically precedes the development of most gastric adenocarcinomas. Alterations such as gastric mucosal atrophy and intestinal metaplasia are merely markers of increased risk, while gastric epithelial dysplasia (GED) represent a direct precursor of cancer. DNA damage and increased mucosal proliferation secondary to H pylori infection, combined with a suitable host susceptibility phenotype (eg, genetic polymorphisms in interleukin IL-1B, IL-1RN, and tumor necrosis factor a TNF-alpha genes), are important factors in this progression pathway. However, only a small minority of patients infected with H. pylori eventually develops gastric cancer, and eradication of H pylori in these patients does not seem to eliminate the risk of cancer completely. It has been shown that atrophy may be a better indicator of risk of cancer than intestinal metaplasia, and remains to be validated in routine clinical practice according to recent proposal for new quantitative methods. It is often associated with pseudopyloric gland metaplasia in the gastric corpus mucosa, which expresses a type of trefoil peptide, the spasmolytic polypeptide (termed spasmolytic polypeptide-expressing metaplasia or SPEM) and has been shown to be linked more closely to gastric cancer than intestinal metaplasia. Better histological characterization of adenomatous (or type I), hyperplastic (foveolar or type II) and tubule-neck (mucocellular or type III) GED, two-tiered grading system (low and high grade dysplasia) as well as the introduction of Padova and Vienna international classifications of dysplasia seem to be more helpful in GED surveillance and comparative studies. A combination of histopathological features, serum markers such as pepsinogen I, and molecular tests that analyze host susceptibility polymorphisms and bacterial virulence factors, may allow development of strategies for early detection of cancer in the future. At present, pathobiology of gastric cancerogenesis is far from known, despite the progressive knowledge on predisposing environmental conditions and genetic and epigenetic abnormalities, including tumour suppressor genes, oncogenes, microsatellite instability and hypermethylation or the significance of E-cadherin mutational status association with hereditary diffuse gastric cancer syndrome. Recent evidence regarding the importance of several histopathologically derived prognostic factors, such as resection margin status and lymph node metastases and their implications have also been discussed. We aim to review these aspects, with special relevance to gastric cancer specimen reporting.

The glycan-binding protein galectin-1 controls survival of epithelial cells along the crypt-villus axis of small intestine

Intestinal epithelial cells serve as mechanical barriers and active components of the mucosal immune system. These cells migrate from the crypt to the tip of the villus, where different stimuli can differentially affect their survival. Here we investigated, using in vitro and in vivo strategies, the role of galectin-1 (Gal-1), an evolutionarily conserved glycan-binding protein, in modulating the survival of human and mouse enterocytes. Both Gal-1 and its specific glyco-receptors were broadly expressed in small bowel enterocytes. Exogenous Gal-1 reduced the viability of enterocytes through apoptotic mechanisms involving activation of both caspase and mitochondrial pathways. Consistent with these findings, apoptotic cells were mainly detected at the tip of the villi, following administration of Gal-1. Moreover, Gal-1-deficient (Lgals1^−/−) mice showed longer villi compared with their wild-type counterparts in vivo. In an experimental model of starvation, fasted wild-type mice displayed reduced villi and lower intestinal weight compared with Lgals1^−/− mutant mice, an effect reflected by changes in the frequency of enterocyte apoptosis. Of note, human small bowel enterocytes were also prone to this pro-apoptotic effect. Thus, Gal-1 is broadly expressed in mucosal tissue and influences the viability of human and mouse enterocytes, an effect which might influence the migration of these cells from the crypt, the integrity of the villus and the epithelial barrier function.

Infection with the gastrointestinal nematode Ostertagia ostertagi in cattle affects mucus biosynthesis in the abomasum

The mucus layer in the gastrointestinal (GI) tract is considered to be the first line of defense to the external environment. Alteration in mucus components has been reported to occur during intestinal nematode infection in ruminants, but the role of mucus in response to abomasal parasites remains largely unclear. The aim of the current study was to analyze the effects of an Ostertagia ostertagi infection on the abomasal mucus biosynthesis in cattle. Increased gene expression of MUC1, MUC6 and MUC20 was observed, while MUC5AC did not change during infection. Qualitative changes of mucins, related to sugar composition, were also observed. AB-PAS and HID-AB stainings highlighted a decrease in neutral and an increase in acidic mucins, throughout the infection. Several genes involved in mucin core structure synthesis, branching and oligomerization, such as GCNT3, GCNT4, A4GNT and protein disulphide isomerases were found to be upregulated. Increase in mucin fucosylation was observed using the lectin UEA-I and through the evaluation of fucosyltransferases gene expression levels. Finally, transcription levels of 2 trefoil factors, TFF1 and TFF3, which are co-expressed with mucins in the GI tract, were also found to be significantly upregulated in infected animals. Although the alterations in mucus biosynthesis started early during infection, the biggest effects were found when adult worms were present on the surface of the abomasal mucosa and are likely caused by the alterations in mucosal cell populations, characterized by hyperplasia of mucus secreting cells.

Markers of bile duct tumors

Biliary tract carcinomas are relatively rare, representing less than 1% of cancers. However, their incidence has increased in Japan and in industrialized countries like the USA. Biliary tract tumors have a poor prognosis and a high mortality rate because they are usually detected late in the course of the disease; therapeutic treatment options are often limited and of minimal utility. Recent studies have shown the importance of serum and molecular markers in the diagnosis and follow up of biliary tract tumors. This review aims to introduce the main features of the most important serum and molecular markers of biliary tree tumors. Some considerable tumor markers are cancer antigen 125, carbohydrate antigen 19-9, carcinoembryonic antigen, chromogranin A, mucin 1, mucin 5, alpha-fetoprotein, claudins and cytokeratins.

Pancreatic cyst fluid and serum mucin levels predict dysplasia in intraductal papillary mucinous neoplasms of the pancreas

INTRODUCTION

There are no reliable markers of dysplasia in patients with incidentally discovered intraductal papillary mucinous neoplasms of the pancreas (IPMN). IPMN dysplasia may be associated with mucin protein (MUC) expression and histopathologic subtype. We hypothesize that MUC expression in cyst fluid and serum can identify lesions with high risk of malignancy.

METHODS

Cyst fluid and serum were collected from 40 patients during pancreatectomy for IPMN between 2005 and 2009. Samples were grouped into low-risk (low-grade or moderate dysplasia, n = 21) and high-risk groups (high-grade dysplasia or carcinoma, n = 19). Mucin expression (MUC1, MUC2, MUC4, and MUC5AC) was assessed utilizing enzyme-linked immunosorbent assays.

RESULTS

MUC2 and MUC4 cyst fluid concentrations were elevated in high-risk versus low-risk groups (10 ± 3.0 ng/ml vs. 4.4 ± 1.2 ng/ml, p = 0.03; 20.6 ± 10.6 ng/ml vs. 4.5 ± 1.4 ng/ml, p = 0.03, respectively). Corresponding serum samples revealed higher levels of MUC5AC in high-risk compared with low-risk patients (19.9 ± 9.3 ng/ml vs. 2.2 ± 1.1 ng/ml, p = 0.04). Histopathologic subtype was significantly associated with grade of dysplasia, and the intestinal subtype displayed increased MUC2 cyst fluid concentrations (13.8 ± 6.5 ng/ml vs. 4.1 ± 0.9 ng/ml, p = 0.02).

CONCLUSIONS

In this study, high-risk IPMN showed elevated cyst fluid concentrations of MUC2 and MUC4, and increased serum levels of MUC5AC. High-risk IPMN also displayed a distinct mucin expression profile in specific histologic subtypes. These data, if validated, may allow surgeons to more appropriately select patients for operative resection.

IR spectral imaging of secreted mucus: a promising new tool for the histopathological recognition of human colonic adenocarcinomas

AIMS

During colonic carcinogenesis, mucin-type glycoproteins are known to undergo quantitative and qualitative alterations. The aim of this study was to determine the value of infrared (IR) spectral histology for the histopathological recognition of colonic adenocarcinomas based on mucin-associated IR spectral markers.

METHODS AND RESULTS

Paraffin-embedded tissue sections of normal human colon and adenocarcinomas were analysed directly by IR-microspectroscopy (IR-MSP), without prior chemical dewaxing. IR-MSP imaging combined with multivariate analysis permitted the construction of IR colour-coded images of the tissue sections providing spatially resolved biochemical information. This allowed localization of mucin-rich areas and provided label-free spectral-based staining of secreted mucus related to the biochemical heterogeneity of its mucin content. IR images of secreted mucus display the same spectral clusters in both normal and adenocarcinomatous colonic tissues, but with significant differences in surface percentages. Such differences allow a distinction between these two tissue types. Spectral variations associated with changes of mucin secondary structure were the most accurate mucus spectral marker for discriminating between normal colon and adenocarcinomas in the sample set.

CONCLUSIONS

IR-MSP imaging provides a new type of histology, independent of visual morphology, presenting tremendous possibilities for discovery and clinical monitoring of cancer markers.

CDX2 expression in the intestinal-type gastric epithelial neoplasia: frequency and significance

CDX2 is an intestinal transcription factor responsible for regulating the proliferation and differentiation of intestinal epithelial cells. In gastric adenocarcinoma, CDX2 expression is known to be associated with limited invasiveness and intestinal phenotypes. The aims of this study were to analyze CDX2 expression in a series of well-characterized cases of gastric epithelial dysplasia, based on the morphologic and mucin phenotypes, and also to analyze CDX2 expression along the metaplasia-dysplasia-carcinoma sequence. CDX2 expression was evaluated in 69 cases of gastric epithelial dysplasia, 88 cases of intestinal-type early gastric cancers, and 56 cases of advanced gastric cancers. Increased CDX2 expression was more frequently associated with adenomatous-type gastric epithelial dysplasia (27/31, 87%) compared with foveolar (7/15, 47%) or hybrid (10/23, 44%) types of gastric epithelial dysplasia (P=0.001). CDX2 expression correlated with an increase in CD10 expression (P=0.005), and a decrease in MUC5AC expression (P=0.001) in gastric epithelial dysplasia. CDX2 expression was also gradually decreased from gastric epithelial dysplasia, to early and advanced gastric cancers (present in 64, 40 and 27% of the cases, respectively). A negative correlation was also observed between CDX2 expression and the depth of tumor invasion. Our results indicate that CDX2 expression is associated with specific morphological and mucin phenotypes of gastric epithelial dysplasias, and decreases progressively with the advancing stage of gastric cancers, suggesting a possible tumor suppressor role for CDX2.

The prenatal development and histochemistry of the ileal mucins in the bovine fetuses

Few studies exist regarding the distribution of intestinal mucins in fetuses of mammalians such as cattle and sheep. In this study, we aimed to describe the changes in the mucin production by ileal epithelium of bovine fetuses during their prenatal development. The goblet cells showed heterogeneity in mucins and the apical cytoplasm of the enterocytes demonstrated Periodic acid Schiff-positive reaction which declined gradually towards the birth. Moreover, the number of the goblet cells containing acidic and mixed mucins augmented, whereas those containing neutral mucins decreased with advancing gestational age. After sixth month of gestation, with the initiation of the ileal Peyer patches and follicle-associated epithelium development, a gradual increase in the number of goblet cells containing sulfomucins was also noticed towards the birth. The presence of different mucins in the ileum of bovine fetuses throughout prenatal development might play a role in the protection of the intestinal mucosa against urinary waste products in swallowed amniotic fluid and bile. Furthermore, mucins can also contribute for the formation of meconium in intra-uterine life and building of strong intestinal barrier with predominating sulfomucins, protecting the intestine against potential pathogens and digestive enzymes after birth.

Cutaneous chronic graft-versus-host disease does not have the abnormal endothelial phenotype or vascular rarefaction characteristic of systemic sclerosis

BACKGROUND

The clinical and histologic appearance of fibrosis in cutaneous lesions in chronic graft-versus -host disease (c-GVHD) resembles the appearance of fibrosis in scleroderma (SSc). Recent studies identified distinctive structural changes in the superficial dermal microvasculature and matrix of SSc skin. We compared the dermal microvasculature in human c-GVHD to SSc to determine if c-GVHD is a suitable model for SSc.

METHODOLOGY/PRINCIPAL FINDINGS

We analyzed skin biopsies of normal controls (n = 24), patients with SSc (n = 30) and c-GVHD with dermal fibrosis (n = 133)). Immunostaining was employed to identify vessels, vascular smooth muscle, dermal matrix, and cell proliferation. C-GVHD and SSc had similar dermal matrix composition and vascular smooth muscle pathology, including intimal hyperplasia. SSc, however, differed significantly from c-GVHD in three ways. First, there were significantly fewer (p = 0.00001) average vessels in SSc biopsies (9.8) when compared with c-GVHD (16.5). Second, in SSc, endothelial markers were decreased significantly (19/19 and 12/14 for VE cadherin and vWF (p = <0.0001 and <0.05), respectively). In contrast, 0/13 c-GVHD biopsies showed loss of staining with canonical endothelial markers. Third, c-GVHD contained areas of microvascular endothelial proliferation not present in the SSc biopsies.

CONCLUSIONS/SIGNIFICANCE

The sclerosis associated with c-GVHD appears to resemble wound healing. Focal capillary proliferation occurs in early c-GVHD. In contrast, loss of canonical endothelial markers and dermal capillaries is seen in SSc, but not in c-GVHD. The loss of VE cadherin in SSc, in particular, may be related to microvascular rarefaction because VE cadherin is necessary for angiogenesis. C-GVHD is a suitable model for studying dermal fibrosis but may not be applicable for studying the microvascular alterations characteristic of SSc.

Serrated Adenoma of Gastric Antrum: Alteration of Mucin Expression Profile and its Role in Carcinogenesis

Serrated adenomas usually occur in colon, the gastric localization is extremely rare. These polyps have their own carcinogenetic pathway with microsatellite instability. In this report, we present a serrated adenoma localized in gastric antrum with four control endoscopies and biopsies. Immunohistochemical panel of MUC1, MUC2, MUC5AC, and MUC6 was applied to the biopsies. Serrated component, MUC 2 expression increased but goblet cells and MUC5AC expression decreased in follow-up biopsies. This lesion probably was originated from a stem cell that had the potential of differentiation in gastric and intestinal way. This might result an incomplete metaplasia for both colon and stomach. Such lesions which originate from either colon or gastric mucosa may be precancerous and their carcinogenetic pathway may not represent its original organ.

Construction of the specific MUC5AC-siRNA expression plasmid and effect of siRNA on proliferation and apoptosis in human bile duct cancer line HCCC-9810

AIM: To observe specific siRNA silencing effect on Mucin-5 subtype AC gene in human intrahepatic cholangiocarcinoma cell line HCCC-9810 as well as to investigate the influence on proliferation and apoptosis after silencing the Mucin-5 subtype AC gene.

METHODS: Three pairs of specific MUC5AC-siRNA were designed and synthesized through transcription in vitro. Three different siRNA expression plasmids (pRNAT-U6.1/Neo-MUC5AC-siRNA1/2/3) were constructed by gene recombination. Then three stable expression plasmids and the comparison plasmid (empty plasmid-transfected control) were transfected into HCCC-9810 by liposome-mediated transfection. Transfection efficiency was evaluated by nonspecific small molecular siRNA (fluorescent conjugate). MUC5AC-mRNA level was detected by RT-PCR. Expression of Mucin-5 subtype AC was investigated by immunohistochemical SABC method. Cell apoptosis and proliferation were analyzed by flow cytometry and MTT, respectively.

RESULTS: The results of gene sequencing indicated that the pRNAT-U6.1/Neo-MUC5AC-siRNA1/2/3 was successfully constructed. After the transfection, the efficiency of fluorescent protein expression reached 28.57%; the results of RT-PCR and immunocytochemistry showed that constructed plasmids down-regulated mRNA and protein of Mucin-5 subtype AC at 48 h after transfection. The results of MTT indicated that the growth of HCCC-9810 was obviously inhibited after silencing the Mucin-5 subtype AC gene. Apoptosis was induced in the tumor cells after suppressing the expression of Mucin-5 subtype AC gene by flow cytometry.

CONCLUSION: Three different stable expression plasmids of siRNA specific for Mucin-5 subtype AC gene obviously inhibit the expression at MUC5AC-mRNA and protein level. The blockage of Mucin-5 subtype AC gene expression in HCCC-9810 cells shows significant effect on cell apoptosis and proliferation.

Mucin overexpression limits the effectiveness of 5-FU by reducing intracellular drug uptake and antineoplastic drug effects in pancreatic tumours

Current treatments for pancreatic cancer have failed to effectively manage the disease, and hence, more effective treatment approaches are urgently needed. Studies suggest that mucin O-glycosylation limits the cytotoxic effect of fluorouracil (5-FU) against the growth of human pancreatic cancer cells in vitro. In the present study, we investigated the relationship between the levels of mucin O-glycosylation expressed in pancreatic tumours and the antitumour effect of 5-FU. The inhibition of O-glycosylation was achieved by intratumoural (IT) injections of benzyl-alpha-GalNAc. Immunohistochemical staining of human pancreatic tumours revealed relatively high (Capan-1) and moderate (HPAF-II) expression levels of MUC1 mucin compared to MUC1 negative control (U-87 MG human glioblastoma) tumours. The antitumour effects of 5-FU (given systemically) against Capan-1 tumours improved significantly following IT injections of benzyl-alpha-GalNAc. Histochemical staining of tumour sections revealed a reduced number of neoplastic cells in tumours exposed to benzyl-alpha-GalNAc prior to 5-FU treatment compared to 5-FU alone. Furthermore, intracellular uptake of 5-FU by Capan-1 cells was significantly greater following injections of benzyl-alpha-GalNAc; however, no such effect was observed with U-87 MG cells. Mucin overexpression reduces intracellular drug uptake, antineoplastic and antitumour drug effects, which may have important clinical implications in treatment.

Hepatocyte nuclear factor 4alpha in the intestinal epithelial cells protects against inflammatory bowel disease

BACKGROUND

Hepatocyte nuclear factor 4alpha (HNF4alpha; NR2A1) is an orphan member of the nuclear receptor superfamily expressed in liver and intestine. While HNF4alpha expression is critical for liver function, its role in the gut and in the pathogenesis of inflammatory bowel disease (IBD) is unknown.

METHODS

Human intestinal biopsies from control and IBD patients were examined for expression of mRNAs encoding HNF4alpha and other nuclear receptors. An intestine-specific HNF4alpha null mouse line (Hnf4alpha(DeltaIEpC)) was generated using an Hnf4alpha-floxed allele and villin-Cre transgene. These mice and their control floxed counterparts (Hnf4alpha(F/F)), were subjected to a dextran sulfate sodium (DSS)-induced IBD colitis protocol and their clinical symptoms and gene expression patterns determined.

RESULTS

In human intestinal biopsies, HNF4alpha was significantly decreased in intestinal tissues from Crohn's disease and ulcerative colitis patients. HNF4alpha expression was also suppressed in the intestine of DSS-treated mice. In Hnf4alpha(DeltaIEpC) mice, disruption of HNF4alpha expression was observed in the epithelial cells throughout the intestine. In the DSS-induced colitis model Hnf4alpha(DeltaIEpC) mice showed markedly more severe changes in clinical symptoms and pathologies associated with IBD including loss of body weight, colon length, and histological morphology as compared with Hnf4alpha(F/F) mice. Furthermore, the Hnf4alpha(DeltaIEpC) mice demonstrate a significant alteration of mucin-associated genes and increased intestinal permeability, which may play an important role in the increased susceptibility to acute colitis following an inflammatory insult.

CONCLUSIONS

While HNF4alpha does not have a major role in normal function of the intestine, it protects the gut against DSS-induced colitis.

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.

Gastric preneoplastic lesions and epithelial dysplasia

The incidence of gastric cancer is declining; however, it remains the second most common cause of cancer-related deaths worldwide. This article describes gastric preneoplastic lesions and epithelial dysplasia. The possible role of Helicobacter pylori infection is emphasized.

Herpes simplex virus type 1 preferentially targets human colon carcinoma: role of extracellular matrix

Viral therapy of cancer (viral oncolysis) is dependent on selective destruction of the tumor tissue compared with healthy tissues. Several factors, including receptor expression, extracellular components, and intracellular mechanisms, may influence viral oncolysis. In the present work, we studied the potential oncolytic activity of herpes simplex virus type 1 (HSV-1), using an organ culture system derived from colon carcinoma and healthy colon tissues of mouse and human origin. HSV-1 infected normal colons ex vivo at a very low efficiency, in contrast to high-efficiency infection of colon carcinoma tissue. In contrast, adenoviral and lentiviral vectors infected both tissues equally well. To investigate the mechanisms underlying the preferential affinity of HSV-1 for the carcinoma tissue, intracellular and extracellular factors were investigated. Two extracellular components, collagen and mucin molecules, were found to restrict HSV-1 infectivity in the healthy colon. The mucin layer of the healthy colon binds to HSV-1 and thereby blocks viral interaction with the epithelial cells of the tissue. In contrast, colon carcinomas express small amounts of collagen and mucin molecules and are thus permissive to HSV-1 infection. In agreement with the ex vivo system, HSV-1 injected into a mouse colon carcinoma in vivo significantly reduced the volume of the tumor. In conclusion, we describe a novel mechanism of viral selectivity for malignant tissues that is based on variance of the extracellular matrix between tumor and healthy tissues. These insights may facilitate new approaches to the application of HSV-1 as an oncolytic virus.

Aberrant gastric apomucin expression in ulcerative colitis and associated neoplasia

AIM

To evaluated the presence of gastric metaplasia in colonic mucosa of patients with ulcerative colitis and its relationship with dysplasia/neoplasia.

MATERIAL AND METHODS

Ninety patients with UC were selected. The duration and the extent of disease were registered in all the cases. Biopsies were histologically and immunohistochemically assessed. Crypt distortion, goblet cell depletion, Paneth cell metaplasia and inflammatory activity were graded, as well as dysplasia and invasive neoplasia (absent or present). Monoclonal antibodies against the gastric apomucins MUC5AC (foveolar) and MUC6 (mucopeptic) were used.

RESULTS

Neoplasia was observed in 16 patients, 8 non-invasive (dysplasia) and 8 invasive (adenocarcinoma). MUC5AC and MUC6 were detected in 63 and 16 out the 90 cases, 70.0% and 17.8%, respectively. The staining was patchy for both antibodies, affecting groups of cells more often than isolated cells. The presence of MUC5AC correlated positively with inflammatory activity and goblet cell depletion (R=0.231, p=0.03 and R=0.211, p=0.048, respectively). The expression of MUC6 correlated positively with age (R=0.297, p=0.005), duration of disease (R=0.287, p=0.008), extent of disease (R=0.342, p=0.001), crypt distortion (R=0.276, p=0.01) and the presence of neoplasia (R=0.483, p<0.00). There was no correlation between Paneth cell metaplasia and apomucin expression.

CONCLUSIONS

Our study demonstrates the aberrant expression of gastric apomucins in UC and suggests that MUC5AC is associated with inflammation while MUC6 is related to the presence of neoplasia. The demonstration of metaplastic cell lineages preceding dysplasia supports the biological link between inflammation and neoplasia, MUC6 emerging as a putative biomarker of dysplasia in ulcerative colitis patients.

Differences in the expression of mucins in various forms of cystitis glandularis

A wide spectrum of glandular epithelial metaplastic changes may be seen in the bladder. Cystitis glandularis (CG) is a well-known metaplastic lesion occurring in the presence of chronic inflammation, but there are a few data about mucin expression in its two subtypes (typical and intestinal). The purpose of the present study was to determine the expression of mucin core proteins and CD10 in the different types of CG. For this examination, we used a panel of monoclonal-specific antibodies for MUC1, MUC2, MUC5AC, and MUC6. CG of the intestinal type expressed MUC5AC both in goblet and columnar cells, and strongly expressed intestinal mucin MUC2 only in goblet cells in all cases. There was no expression of MUC1, MUC6, and CD10 in the metaplastic cells. CG of the typical type showed an expression of MUC1 similar to normal urothelium, but the CD10 expression was more intensive than in the control. The mucin expression profile in the different types of CG allows the identification of "gastric mucin" (MUC5AC) together with intestinal mucin (MUC2), while typical CG (CGTP) retains MUC1. Different and contrasting immunoprofiles were evident in various forms of CG. The absence of CD 10 in CG of the intestinal type is a finding that points towards an incomplete form of urinary bladder metaplasia.

Leptin modulates the expression of secreted and membrane-associated mucins in colonic epithelial cells by targeting PKC, PI3K, and MAPK pathways

Mucins play an essential role in the protection and repair of gastrointestinal mucosa. We recently showed that luminal leptin strongly stimulated mucin secretion in vivo in rat colon. In the present study, we challenged the hypothesis that leptin may act directly on goblet cells to induce mucin expression in rat and human intestinal mucin-producing cells (DHE and HT29-MTX). The endoluminal effect of leptin was also studied in vivo in rat perfused colon model. The presence of leptin receptors was demonstrated in the two cell lines by Western blot and RT-PCR. In rat DHE cells, leptin (0.01-10 nmol/l, 60 min) dose dependently increased the secretion of mucins (210 +/- 3% of controls) and the expression of Muc2, Muc3, and Muc4 (twofold basal level) but not of Muc1 and Muc5AC. Luminal perfusion of leptin (60 min, 0.1-100 nmol/l) in rat colon also increased the mRNA level of Muc2, Muc3, and Muc4 but not of Muc1. In human HT29-MTX cells, leptin (0.01-10 nmol/l, 60 min) dose dependently enhanced MUC2, MUC5AC, and MUC4 mRNA levels. These effects were prevented by pretreatment of cells with the leptin mutein L39A/D40A/F41A, which acts as a receptor antagonist. Finally, pathway inhibition experiments suggest that leptin increased mucin expression by activating PKC-, phosphatidyl inositol 3-kinase-, and MAPK-dependent pathways but not the JAK/STAT pathway. In conclusion, leptin may contribute significantly to membrane-associated and secreted mucin production via a direct stimulation of colonic epithelial cells and the activation of leptin receptors. These data are consistent with a role for leptin in regulation of the intestinal barrier function.

Increased susceptibility to colitis and colorectal tumors in mice lacking core 3-derived O-glycans

Altered intestinal O-glycan expression has been observed in patients with ulcerative colitis and colorectal cancer, but the role of this alteration in the etiology of these diseases is unknown. O-glycans in mucin core proteins are the predominant components of the intestinal mucus, which comprises part of the intestinal mucosal barrier. Core 3–derived O-glycans, which are one of the major types of O-glycans, are primarily expressed in the colon. To investigate the biological function of core 3–derived O-glycans, we engineered mice lacking core 3 β1,3-N-acetylglucosaminyltransferase (C3GnT), an enzyme predicted to be important in the synthesis of core 3–derived O-glycans. Disruption of the C3GnT gene eliminated core 3–derived O-glycans. C3GnT-deficient mice displayed a discrete, colon-specific reduction in Muc2 protein and increased permeability of the intestinal barrier. Moreover, these mice were highly susceptible to experimental triggers of colitis and colorectal adenocarcinoma. These data reveal a requirement for core 3–derived O-glycans in resistance to colonic disease.

Gallbladder mucin production and calcium carbonate gallstones in children

In contrast to adults, calcium carbonate gallstones are relatively common in children. Their pathogenesis is poorly understood. Cystic duct obstruction promotes calcium carbonate formation in bile and increases gallbladder mucin production. We tested the hypothesis that mucin producing epithelial cells would be increased in gallbladders of children with calcium carbonate gallstones. Archival gallbladder specimens from 20 consecutive children who had undergone elective cholecystectomy for cholelithiasis were examined. In each case, gallstone composition was determined by Fourier transform infrared microspectroscopy. Gallbladder specimens from six children who had undergone cholecystectomy for conditions other than cholelithiasis during the same period were used as controls. Multiple sections were examined in a blinded fashion and scored semiquantitatively for mucin production using two stains (alcian blue and periodic acid-Schiff). Increased mucin staining was observed in 50% or more epithelial cells in five gallbladder specimens from seven children with calcium carbonate stones, compared to 5 of 13 with other stone types (P = 0.17) and none of the control gallbladders (P = 0.02). Gallbladders containing calcium carbonate stones were significantly more likely than those containing other stone types or controls to contain epithelial cells with the greatest mucin content (P = 0.03). Gallbladders containing calcium carbonate stones were also more likely to show the ulcer-associated cell lineage. These results demonstrate an increase in mucin producing epithelial cells in gallbladders from children containing calcium carbonate stones. This supports the hypothesis that cystic duct obstruction leading to increased gallbladder mucin production may play a role in the development of calcium carbonate gallstones in children.

Mucin-type O-glycans in human colon and breast cancer: glycodynamics and functions

The glycoproteins of tumour cells are often abnormal, both in structure and in quantity. In particular, the mucin-type O-glycans have several cancer-associated structures, including the T and Tn antigens, and certain Lewis antigens. These structural changes can alter the function of the cell, and its antigenic and adhesive properties, as well as its potential to invade and metastasize. Cancer-associated mucin antigens can be exploited in diagnosis and prognosis, and in the development of cancer vaccines. The activities and Golgi localization of glycosyltransferases are the basis for the glycodynamics of cancer cells, and determine the ranges and amounts of specific O-glycans produced. This review focuses on the glycosyltransferases of colon and breast cancer cells that determine the pathways of mucin-type O-glycosylation, and the proposed functional and pathological consequences of altered O-glycans.