Role In Mucosal Protection Research Articles

Spatiotemporal observations of host-pathogen interactions in mucosa during SARS-CoV-2 infection indicate a protective role of ILC2s

ABSTRACT Innate lymphoid cells (ILCs) play a crucial role in mucosal protection and tissue homeostasis. However, the early mucosal defense mechanisms against the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus have not been fully understood to date. This knowledge gap has motivated us to develop a coronavirus disease 2019-like mouse model to investigate the interactions between the virus, its receptor, and ILCs. In our study, we conducted intranasal challenges using pseudovirus expressing Spike (PSV-S) to examine the expression patterns of humanized ACE2 (chiACE2) and the transduction of PSV-S in lung and ileum tissues over a specified time period. Within a span of 72 hours, we observed an intense viral transduction induced by the spike protein, which was detected from the central bronchus to the bronchiole and alveolus in the lung (levels 3 to 8). Similarly, we observed the transduction of PSV-S in the villi and crypts of the ileum. Interestingly, our precise three-dimensional colocalization analysis revealed that only 73.74% ± 1.76% of the PSV-S transduction depended on chiACE2. Furthermore, type 2 innate lymphoid cells (ILC2s) exhibited the most pronounced activation in the gut mucosa. This finding indicates the significant role of ILC2s as contributors to the mucosal defense against viral infections. Our data shed light on the critical involvement of ILC2s and their intricate three-dimensional regulatory network in combating SARS-CoV-2 within the mucosa. IMPORTANCE Our study revealed the spatial interaction between humanized ACE2 and pseudovirus expressing Spike, emphasizing the role of type 2 innate lymphoid cells during the initial phase of viral infection. These findings provide a foundation for the development of mucosal vaccines and other treatment approaches for both pre- and post-infection management of coronavirus disease 2019.

Sulphide donors affect the expression of mucin and sulphide detoxification genes in the mucosal organs of Atlantic salmon (Salmo salar).

Hydrogen sulphide (H2S) is a gas that affects mucosal functions in mammals. However, its detrimental effects are less understood in fish despite being known to cause mass mortality. Here we used explant models to demonstrate the transcriptional responses of Atlantic salmon (Salmo salar) mucosa to the sulphide donor sodium hydrosulphide (NaHS). The study focused on two groups of genes: those encoding for sulphide detoxification and those for mucins. Moreover, we performed pharmacological studies by exposing the organ explants to mucus-interfering compounds and consequently exposed them to a sulphide donor. Exposure to NaHS significantly affected the expression of sulphide:quinone oxidoreductase (sqor1, sqor2) and mucin-encoding genes (muc5ac, muc5b). The general profile indicated that NaHS upregulated the expression of sulphide detoxification genes while a significant downregulation was observed with mucins. These expression profiles were seen in both organ explant models. Pharmacological stimulation and inhibition of mucus production used acetylcholine (ACh) and niflumic acid (NFA), respectively. This led to a significant regulation of the two groups of marker genes in the gills and olfactory rosette explants. Treatment of the mucosal organ explants with the mucus-interfering compounds showed that low dose NFA triggered more substantial changes while a dose-dependent response could not be established with ACh. Pharmacological interference demonstrated that mucins played a crucial role in mucosal protection against H2S toxicity. These results offer insights into how a sulphide donor interfered with mucosal responses of Atlantic salmon and are expected to contribute to our understanding of the least explored H2S-fish interactions-particularly at the mucosa.

SARS-CoV2 pneumonia recovery is linked to expansion of innate lymphoid cells type 2 expressing CCR10.

Accelerate lung repair in SARS‐CoV‐2 pneumonia is essential for pandemic handling. Innate lymphoid cells (ILCs) are likely players, given their role in mucosal protection and tissue homeostasis. We studied ILC subpopulations at two time points in a cohort of patients admitted in the hospital due to SARS‐CoV‐2 infection. COVID‐19 patients with moderate/severe respiratory failure featured profound depletion of circulating ILCs at hospital admission, in agreement with overall lymphocyte depletion. However, ILCs recovered in direct correlation with lung function improvement as measured by oxygenation index and in negative association with inflammatory and lung/endothelial damage markers like RAGE. While both ILC1 and ILC2 expanded, ILC2 showed the most striking phenotype changes, with CCR10 upregulation in strong correlation with these parameters. Overall, CCR10+ ILC2 emerge as relevant contributors to SARS‐CoV‐2 pneumonia recovery.

Qingchang Wenzhong Decoction Accelerates Intestinal Mucosal Healing Through Modulation of Dysregulated Gut Microbiome, Intestinal Barrier and Immune Responses in Mice.

Inflammatory bowel disease (IBD), a group of multifactorial and inflammatory infirmities, is closely associated with dysregulation of gut microbiota and host metabolome, but effective treatments are currently limited. Qingchang Wenzhong Decoction (QCWZD) is an effective and classical traditional herbal prescription for the treatment of IBD and has been proved to attenuate intestinal inflammation in a model of acute colitis. However, the role of QCWZD in recovery phase of colitis is unclear. Here, we demonstrated that mice treated with QCWZD showed a faster recovery from dextran sulfate sodium (DSS)-induced epithelial injury, accompanied by reduced mucosal inflammation and attenuated intestinal dysbiosis using bacterial 16S rRNA amplicon sequencing compared to those receiving sterile water. The protective effects of QCWZD are gut microbiota dependent, as demonstrated by fecal microbiome transplantation and antibiotics treatment. Gut microbes transferred from QCWZD-treated mice displayed a similar role in mucosal protection and epithelial regeneration as QCWZD on colitis in mice, and depletion of the gut microbiota through antibiotics treatments diminished the beneficial effects of QCWZD on colitis mice. Moreover, metabolomic analysis revealed metabolic profiles alternations in response to the gut microbiota reprogrammed by QCWZD intervention, especially enhanced tryptophan metabolism, which may further accelerate intestinal stem cells-mediated epithelial regeneration to protect the integrity of intestinal mucosa through activation of Wnt/β-catenin signals. Collectively, our results suggested that orally administrated QCWZD accelerates intestinal mucosal healing through the modulation of dysregulated gut microbiota and metabolism, thus regulating intestinal stem cells-mediated epithelial proliferation, and hold promise for novel microbial-based therapies in the treatment of IBD.

Lack of Gut Secretory Immunoglobulin A in Memory B-Cell Dysfunction-Associated Disorders: A Possible Gut-Spleen Axis

Background: B-1a B cells and gut secretory IgA (SIgA) are absent in asplenic mice. Human immunoglobulin M (IgM) memory B cells, which are functionally equivalent to mouse B-1a B cells, are reduced after splenectomy.Objective: To demonstrate whether IgM memory B cells are necessary for generating IgA-secreting plasma cells in the human gut.Methods: We studied intestinal SIgA in two disorders sharing the IgM memory B cell defect, namely asplenia, and common variable immune deficiency (CVID).Results: Splenectomy was associated with reduced circulating IgM memory B cells and disappearance of intestinal IgA-secreting plasma cells. CVID patients with reduced circulating IgM memory B cells had a reduced frequency of gut IgA+ plasma cells and a disrupted film of SIgA on epithelial cells. Toll-like receptor 9 (TLR9) and transmembrane activator and calcium-modulator and cyclophilin ligand interactor (TACI) induced IgM memory B cell differentiation into IgA+ plasma cells in vitro. In the human gut, TACI-expressing IgM memory B cells were localized under the epithelial cell layer where the TACI ligand a proliferation inducing ligand (APRIL) was extremely abundant.Conclusions: Circulating IgM memory B cell depletion was associated with a defect of intestinal IgA-secreting plasma cells in asplenia and CVID. The observation that IgM memory B cells have a distinctive role in mucosal protection suggests the existence of a functional gut-spleen axis.

451 Late-Breaking: Saccharomyces cerevisiae boulardii stimulates immunoglobulin A production in the gut of neonate dairy calves

Abstract Calves are born with a naïve immune system at birth and undergo rapid changes in terms of immunity. This study focused on evaluating the effect of S. boulardii CNCMI-1079 (SCB) supplementation from birth on immunoglobulin A (IgA) production in the gut of neonate dairy calves. Holstein bull calves (n = 20) were delivered naturally and immediately removed from the dam, and housed in individual straw-bedded pens with a random assignment to a treated group (supplementation with SCB: 10 × 109 CFU/d in each morning meal) or a control group (no supplementation). All the calves received two first meals of a standardized colostrum at 2 h and 12 h after birth followed by two meals per day of milk replacer (7.5% of birth BW; 260 g/kg CP; 160 g/kg crude fat, at 150g/L). Calves were euthanized at 7 d of age and samples from jejunum, ileum and colon were collected. The concentration of IgA and the gene expressions of polymeric Ig receptor (pIgR) and a receptor of plasma B cells (CD79α) were compared between the two groups and among the locations. The expression of CD79α was up-regulated in the ileum compared to jejunum and colon tissues (P < 0.01), whereas pIgR down-regulated in the ileum compared to jejunum and colon (P < 0.01). The supplementation of SCB increased the IgA concentration in the ileum and colon of treated calves compared to the control calves (respectively 1.98 ± 0.09 vs 1.18 ± 0.15 mg/g DM of ileum content, and 1.45 ± 0.14 vs 0.59 ± 0.06 mg/g DM of colon content, P < 0.001). The results suggest that one of the mechanisms by which SCB exerts an immunoprotective effect in the gut is by stimulation of IgA’s secretion which may play a major role in mucosal protection in neonatal calves.

Trefoil Factor Family: Unresolved Questions and Clinical Perspectives

The trefoil factor family of peptides (TFF1, TFF2, TFF3) with their lectin activities play important roles in mucosal protection and repair. However, major gaps in understanding their molecular function have hampered therapeutic development for gastrointestinal disorders. We provide here a critical overview of the status quo.

TFF1 Promotes EMT-Like Changes through an Auto-Induction Mechanism.

Trefoil factor 1 (TFF1) is a small secreted protein expressed in the gastrointestinal tract where, together with the other two members of its family, it plays an essential role in mucosal protection and repair against injury. The molecular mechanisms involved in the protective function of all three TFF proteins are not fully elucidated. In this paper, we investigated the role of TFF1 in epithelial to mesenchymal transition (EMT) events. The effects of TFF1 on cellular models in normoxia and/or hypoxia were evaluated by western blot, immunofluorescence, qRT-PCR and trans-well invasion assays. Luciferase reporter assays were used to assess the existence of an auto-regulatory mechanism of TFF1. The methylation status of TFF1 promoter was measured by high-resolution melting (HRM) analysis. We demonstrate a TFF1 auto-induction mechanism with the identification of a specific responsive element located between −583 and −212 bp of its promoter. Our results suggest that TFF1 can regulate its own expression in normoxic, as well as in hypoxic, conditions acting synergistically with the hypoxia-inducible factor 1 (HIF-1α) pathway. Functionally, this auto-induction mechanism seems to promote cell invasion and EMT-like modifications in vitro. Additionally, exogenously added human recombinant TFF1 protein was sufficient to observe similar effects. Together, these findings suggest that the hypoxic conditions, which can be induced by gastric injury, promote TFF1 up-regulation, strengthened by an auto-induction mechanism, and that the trefoil peptide takes part in the epithelial-mesenchymal transition events eventually triggered to repair the damage.

Effects of Sodium Butyrate Treatment on Histone Modifications and the Expression of Genes Related to Epigenetic Regulatory Mechanisms and Immune Response in European Sea Bass (Dicentrarchus Labrax) Fed a Plant-Based Diet.

Bacteria that inhabit the epithelium of the animals’ digestive tract provide the essential biochemical pathways for fermenting otherwise indigestible dietary fibers, leading to the production of short-chain fatty acids (SCFAs). Of the major SCFAs, butyrate has received particular attention due to its numerous positive effects on the health of the intestinal tract and peripheral tissues. The mechanisms of action of this four-carbon chain organic acid are different; many of these are related to its potent regulatory effect on gene expression since butyrate is a histone deacetylase inhibitor that play a predominant role in the epigenetic regulation of gene expression and cell function. In the present work, we investigated in the European sea bass (Dicentrarchus labrax) the effects of butyrate used as a feed additive on fish epigenetics as well as its regulatory role in mucosal protection and immune homeostasis through impact on gene expression. Seven target genes related to inflammatory response and reinforcement of the epithelial defense barrier [tnfα (tumor necrosis factor alpha) il1β, (interleukin 1beta), il-6, il-8, il-10, and muc2 (mucin 2)] and five target genes related to epigenetic modifications [dicer1(double-stranded RNA-specific endoribonuclease), ehmt2 (euchromatic histone-lysine-N-methyltransferase 2), pcgf2 (polycomb group ring finger 2), hdac11 (histone deacetylase-11), and jarid2a (jumonji)] were analyzed in fish intestine and liver. We also investigated the effect of dietary butyrate supplementation on histone acetylation, by performing an immunoblotting analysis on liver core histone extracts. Results of the eight-week-long feeding trial showed no significant differences in weight gain or SGR (specific growth rate) of sea bass that received 0.2% sodium butyrate supplementation in the diet in comparison to control fish that received a diet without Na-butyrate. Dietary butyrate led to a twofold increase in the acetylation level of histone H4 at lysine 8, but showed no effect on the histone H3 at Lys9. Moreover, two different isoforms of histone H3 that might correspond to the H3.1 and H3.2 isoforms previously found in terrestrial animals were separated on the immunoblots. The expression of four (il1 β, il8, irf1, and tnfα) out of seven analyzed genes related to mucosal protection and inflammatory response was significantly different between the two analyzed tissues but only il10 showed differences in expression due to the interaction between tissue and butyrate treatment. In addition, butyrate caused significant changes in vivo in the expression of genes related to epigenetic regulatory mechanisms such as hdac11, ehmt2, and dicer1. Statistical analysis by two-way ANOVA for these genes showed not only significant differences due to the butyrate treatment, but also due to the interaction between tissue and treatment.

Endomicroscopic and Transcriptomic Analysis of Impaired Barrier Function and Malabsorption in Environmental Enteropathy.

IntroductionEnvironmental enteropathy (EE) is associated with growth failure, micronutrient malabsorption and impaired responses to oral vaccines. We set out to define cellular mechanisms of impaired barrier function in EE and explore protective mechanisms.MethodsWe studied 49 adults with environmental enteropathy in Lusaka, Zambia using confocal laser endomicroscopy (CLE); histology, immunohistochemistry and mRNA sequencing of small intestinal biopsies; and correlated these with plasma lipopolysaccharide (LPS) and a zinc uptake test.ResultsCLE images (median 134 for each study) showed virtually ubiquitous small intestinal damage. Epithelial defects, imaged by histology and claudin 4 immunostaining, were predominantly seen at the tips of villi and corresponded with leakage imaged in vivo by CLE. In multivariate analysis, circulating log-transformed LPS was correlated with cell shedding events (β = 0.83; P = 0.035) and with serum glucagon-like peptide-2 (β = -0.13; P = 0.007). Zinc uptake from a test dose of 25mg was attenuated in 30/47 (64%) individuals and in multivariate analysis was reduced by HIV, but positively correlated with GLP-2 (β = 2.72; P = 0.03). There was a U-shaped relationship between circulating LPS and villus surface area. Transcriptomic analysis identified 23 differentially expressed genes in severe enteropathy, including protective peptides and proteins.ConclusionsConfocal endomicroscopy, claudin 4 immunostaining and histology identify epithelial defects which are probably sites of bacterial translocation, in the presence of which increased epithelial surface area increases the burden of translocation. GLP 2 and other protective peptides may play an important role in mucosal protection in EE.

Salivary antibody levels in adolescents in response to a meningococcal serogroup C conjugate booster vaccination nine years after priming: systemically induced local immunity and saliva as potential surveillance tool

BackgroundIn several countries large-scale immunization of children and young adults with Meningococcal serogroup C (MenC) conjugate vaccines has induced long-standing herd protection. Salivary antibodies may play an important role in mucosal protection against meningococcal acquisition and carriage. AimTo investigate antibody levels in (pre)adolescents primed 9 years earlier with a single dose of MenC-polysaccharide tetanus toxoid conjugated (MenC-TT) vaccine and the response to a booster vaccination, with special focus on age-related differences and the relation between salivary and serum antibody levels. MethodsNine years after priming, healthy 10- (n=91), 12- (n=91) and 15-year-olds (n=86) received a MenC-TT booster vaccination. Saliva and serum samples were collected prior to and 1 month and 1 year after vaccination. MenC-polysaccharide(MenC-PS)-specific antibody levels were measured using a fluorescent-bead-based multiplex immunoassay. ResultsBefore the booster, MenC-PS-specific IgG and IgA levels in saliva and serum were low and correlated with age at priming. The booster induced a marked increase in salivary MenC-PS-specific IgG (>200-fold), but also in IgA (∼10-fold). One year after the booster, salivary IgG and IgA had remained above pre-booster levels in all age groups (∼20-fold and ∼3-fold, respectively), with persistence of highest levels in the 15-year-olds. MenC-PS-specific IgG and IgA levels in saliva strongly correlated with the levels in serum. ConclusionParenteral MenC-TT booster vaccination induces a clear increase in salivary MenC-PS-specific IgG and IgA levels and persistence of highest levels correlates with age. The strong correlation between serum and salivary antibody levels indicate that saliva may offer an easy and reliable tool for future antibody surveillance.

Trefoil factor family (TFF) proteins as potential serum biomarkers in patients with metastatic colorectal cancer.

Trefoil factor family (TFF) is composed of three secretory proteins (TFF1, TFF2 and TFF3) that play an important role in mucosal protection of gastrointestinal tract. Their overexpression in colorectal tumors seems to be associated with more aggressive disease. We collected serum samples from 79 healthy controls and 97 patients with metastatic colorectal cancer at the time of diagnosis or at progression. Serum levels of TTF1-3, CEA and CA19-9 were measured by ELISA. Serum TFF1 and TFF3 levels were significantly higher in patients with colorectal cancer compared to healthy controls (p < 0.0001). Moreover, serum levels of TFF3 correlated with extent of liver involvement in patient without pulmonary metastases and patients with higher TFF3 levels had significantly worse outcome (p < 0.0001). Compared to CEA and CA19-9, TFF3 had higher sensitivity and the same specificity. Our results indicate that TFF3 is an effective biomarker in patients with metastatic colorectal cancer with higher sensitivity than CEA aCA19-9. TFF3 levels strongly correlate with extension of liver disease and seem to have prognostic value.

Trefoil Factor Expression in a Human Model of the Early Stages of Barrett's Esophagus.

Trefoil proteins are believed to have an important role in mucosal protection and repair in the gastrointestinal tract. They are well recognized in Barrett's esophagus and considered a potential biomarker for the condition. Metaplasia occurring in the esophageal remnant after esophagectomy is a human model for the early stages of development of Barrett's esophagus. To assess expression of trefoil proteins in post-esophagectomy columnar epithelium and to use trefoils as a molecular tool to understand regenerative mucosa in the esophagus. Patients with columnar metaplasia in the esophageal remnant were recruited from a large esophago-gastric cancer center. Trefoil factor expression was determined using immunohistochemical techniques. Samples were obtained from 37 patients. TFF1 and TFF2 were expressed by all samples in a similar pattern to that described in studies of sporadic Barrett's esophagus. TFF3 was less widely expressed and was significantly associated with time elapsed between surgery and endoscopy. Median time from surgery to endoscopy was 8.1 years for patients with TFF3 expression versus 3.4 years for those without (p = 0.004). Widespread expression of trefoils in this environment suggests that these proteins have an important role in development of Barrett's metaplasia. TFF3 expression may be absent in the early stages of metaplasia and may represent more established columnar epithelium. Biopsy samples from post-esophagectomy patients provide a valuable resource to study the early stages of Barrett's esophagus.

Ellagic acid modulates the expression of oral innate immune mediators: potential role in mucosal protection.

Ellagic acid (EA) found in various fruits such as pomegranates, blackberries, raspberries, strawberries, and walnuts has different pharmacological functions including antioxidant, antitumor, antiallergic, anti-inflammatory, antibacterial, and antiviral activities. It is not known, however, if EA could enhance mucosal innate immunity. Our goal was to determine the effects of EA on the expression of innate immune mediators produced by oral epithelial cells. Culture of primary human gingival epithelial cells (HGEs) was performed in duplicate, and after the primary HGEs had been treated with EA at a concentration ranging from 12.5 to 100 μM for 18 h the cells and supernatants were harvested. The expression of innate immune mediators including human β-defensin 2 (hBD2), secretory leukocyte protease inhibitor (SLPI), and various cytokines and chemokines was measured at both transcriptional and translational levels by using quantitative real-time PCR, ELISA, and Luminex assay. In the presence of EA, the expression of hBD2-and SLPI mRNA was 3.7-folds and 2.6-folds greater than untreated controls, respectively, and consistent with their secreted protein levels. For cytokines and chemokines, increased expression of RANTES, IL-2, and IL-1β was found in response to EA. In contrast, EA decreased the expression of IL-6, IL-8, and TNF-α. This study demonstrated that oral innate immunity is affected by EA found in fruits. Thus, it may play some roles in mucosal innate immunity. The potential of EA for modulating the innate immune mediators may lead to developing a new topical agent to treat and/or prevent immune-mediated oral diseases.

Circulating Serum Trefoil Factor 3 (TFF3) Is Dramatically Increased in Chronic Kidney Disease

ObjectivesTrefoil factor 3 (TFF3) is a small peptide that plays an important role in mucosal protection, cell proliferation, and cell migration. The aberrant expression of TFF3 is correlated with gastrointestinal inflammation, solid tumors, and other clinical diseases. The objective of this study was to identify the distribution characteristics of serum TFF3 in common clinical diseases.Materials and MethodsA large prospective randomized study of 1,072 Chinese patients was performed using an enzyme-linked immunosorbent assay (ELISA) to examine the serum TFF3 concentrations in patients with different diseases. A matched case-control study was conducted on patients with chronic kidney disease (CKD) stages 1–5. Immunohistochemistry (IHC) was performed using renal tissues to determine the relationship between the severity of CKD and the serum and urine concentrations of TFF3 peptides.ResultsThe mean serum concentrations of TFF3 in patients with CKD, metastatic and secondary carcinoma (MC) and acute gastroenteritis (AG) (200.9 ng/ml, 95.7 ng/ml and 71.7 ng/ml, respectively) were significantly higher than those in patients with other common clinical diseases. A positive correlation tendency was observed between the serum TFF3 concentrations and the severity of CKD. The mean serum TFF3 values for CKD stages 1–5 were 23.6 ng/ml, 29.9 ng/ml, 54.9 ng/ml, 85.0 ng/ml and 176.6 ng/ml, respectively. The same trend was observed in the urine TFF3 concentrations and the CKD stages. The creatinine(Cr)-corrected concentrations of TFF3 in urine were 367.1 ng/mg·Cr, 910.6 ng/mg·Cr, 1,149.0 ng/mg·Cr, 1,610.0 ng/mg·Cr and 3,475.0 ng/mg·Cr for CKD stages 1–5, respectively. IHC revealed that TFF3 expression was concentrated in tubular epithelial cells.ConclusionsThe influence of kidney injuries must be fully considered when performing clinical TFF3 research. Further studies on TFF3 in CKD will contribute to our understanding of its pathological roles and mechanisms in other diseases.

NHE8 plays an important role in mucosal protection via its effect on bacterial adhesion

The Na⁺/H⁺ exchanger NHE8 is expressed on the apical membrane of intestinal epithelial cells and is particularly abundant in the colon. Our previous study showed that Muc2 expression was significantly reduced in NHE8-knockout (NHE8-/-) mice, suggesting that NHE8 plays a role in mucosal protection in the colon. The current study confirms and extends our studies on the role of NHE8 in mucosal protection. The number of bacteria attached on the distal colon was significantly increased in NHE8-/- mice compared with their wild-type littermates. As expected, IL-4 expression was markedly increased in NHE8-/- mice compared with wild-type mice. Immunohistochemistry showed disorganization in the mucin layer of NHE8-/- mice, suggesting a possible direct bacteria-epithelia interaction. Furthermore, NHE8-/- mice were susceptible to dextran sodium sulfate-induced mucosal injury. In wild-type mice, dextran sodium sulfate treatment inhibited colonic NHE8 expression. In Caco-2 cells, the absence of NHE8 expression resulted in higher adhesion rates of Salmonella typhimurium but not Lactobacillus plantarum. Similarly, in vivo, S. typhimurium adhesion rate was increased in NHE8-/- mice compared with wild-type mice. Our study suggests that NHE8 plays important roles in protecting intestinal epithelia from infectious bacterial adherence.

Mucins in Gastric Cancer - An Update.

Mucins are high-molecular-weight glycoproteins expressed throughout the gastrointestinal tract, with a key role in mucosal protection and function. In gastric cancer expression of MUC5AC and MUC1 is reduced and denovo expression of MUC2 occurs. With progressive loss of tumor differentiation and increased tumor stage, expression of MUC5AC and MUC1 is further reduced, and MUC2 decreases. Isolated MUC2 expression (the intestinal phenotype) correlates with metastatic spread and poor survival. There is emerging evidence that MUC1 acts as an oncoprotein when overexpressed. The cytoplasmic tail of MUC1 interacts with the H. pylori virulence factor cagA and is a major effector of the wnt-β catenin intracellular signalling cascade. Polymorphism in the MUC1 gene has been identified in gastric cancer patients and may have a prospective role in the stratification of high-risk subjects. The MUC1 gene also mediates resistance to the recombinant HER2/neu antibody trastuzumab. Future research efforts will examine targeting MUC1 for therapeutic purposes.

5 Acid-Induced Stimulation of the NHE2 Promoter Activity is Mediated by Transcription Factor EGR-1 in the Human Intestinal Epithelial Cell Line C2BBe1

NHE8 is a member of the SLC9 family. This Na+/H+ exchanger is expressed on the apical membrane of intestinal epithelial cells. Although NHE8 has been shown to be important for intestinal sodium absorption early in development, its physiological role in the gastrointestinal tract remains unknown. By using NHE8 knockout (NHE8KO) mouse model, we discovered that NHE8 plays an important role in protecting the gastric mucosa against gastric acid. Stomach tissue was isolated from NHE8KO mice and their wild-type littermates. Localization of NHE8 expression in the stomach was detected using Immunohistochemistry. Mucosal surface pH was measured using a surface pH meter. Histology of the stomach of NHE8KOmice was also analyzed. RNA was isolated and used for PCR to detect the expression of PAT1 and DRA. Total tissue lysate was prepared for Western detection of NHE8, PAT1 and DRA. Immunohistochemistry indicated that NHE8 is expressed on the apical membrane of gastric epithelial cells. Histological evaluation showed no abnormality of the stomach in NHE8KO mice. Interestingly, higher incidence of gastric bleeding was observed in NHE8KO mice. The appearance of ulcers was seen in the glandular stomach. Mucosal surface pH measurement indicated that NHE8KO mice had decreased mucosal surface pH compared to wild-type mice (3.72 ± 0.13 in NHE8KO vs. 4.26 ± 0.09 in wild-type). Lower surface pH of NHE8KO gastric mucosa suggests that HCO3secretion may be altered. Therefore, we studied the expression of PAT1 and DRA in NHE8KO mice. Indeed, PAT1 and DRA mRNA expression in the stomach of NHE8KO mice were significantly reduced by ~30% and ~90%, respectively, in NHE8KO mice compared to their wild-type littermates. At the protein expression level, PAT1 protein abundance was reduced by ~70% and DRA protein abundance was nearly abolished in NHE8KO mice. Thus NHE8 may play an important role in mucosal protection by participating bicarbonate secretion.

1 Loss of NHE8 Expression Results in Gastric Ulcers in Mice

NHE8 is a member of the SLC9 family. This Na+/H+ exchanger is expressed on the apical membrane of intestinal epithelial cells. Although NHE8 has been shown to be important for intestinal sodium absorption early in development, its physiological role in the gastrointestinal tract remains unknown. By using NHE8 knockout (NHE8KO) mouse model, we discovered that NHE8 plays an important role in protecting the gastric mucosa against gastric acid. Stomach tissue was isolated from NHE8KO mice and their wild-type littermates. Localization of NHE8 expression in the stomach was detected using Immunohistochemistry. Mucosal surface pH was measured using a surface pH meter. Histology of the stomach of NHE8KOmice was also analyzed. RNA was isolated and used for PCR to detect the expression of PAT1 and DRA. Total tissue lysate was prepared for Western detection of NHE8, PAT1 and DRA. Immunohistochemistry indicated that NHE8 is expressed on the apical membrane of gastric epithelial cells. Histological evaluation showed no abnormality of the stomach in NHE8KO mice. Interestingly, higher incidence of gastric bleeding was observed in NHE8KO mice. The appearance of ulcers was seen in the glandular stomach. Mucosal surface pH measurement indicated that NHE8KO mice had decreased mucosal surface pH compared to wild-type mice (3.72 ± 0.13 in NHE8KO vs. 4.26 ± 0.09 in wild-type). Lower surface pH of NHE8KO gastric mucosa suggests that HCO3secretion may be altered. Therefore, we studied the expression of PAT1 and DRA in NHE8KO mice. Indeed, PAT1 and DRA mRNA expression in the stomach of NHE8KO mice were significantly reduced by ~30% and ~90%, respectively, in NHE8KO mice compared to their wild-type littermates. At the protein expression level, PAT1 protein abundance was reduced by ~70% and DRA protein abundance was nearly abolished in NHE8KO mice. Thus NHE8 may play an important role in mucosal protection by participating bicarbonate secretion.

Challenges in Management of Pericardial Effusion in Patients with HIV/AIDS

Mucins are high-molecular-weight glycoproteins expressed throughout the gastrointestinal tract, with a key role in mucosal protection and function. In gastric cancer expression of MUC5AC and MUC1 is reduced and denovo expression of MUC2 occurs. With progressive loss of tumor differentiation and increased tumor stage, expression of MUC5AC and MUC1 is further reduced, and MUC2 decreases. Isolated MUC2 expression (the intestinal phenotype) correlates with metastatic spread and poor survival. There is emerging evidence that MUC1 acts as an oncoprotein when overexpressed. The cytoplasmic tail of MUC1 interacts with the H. pylori virulence factor cagA and is a major effector of the wnt-β catenin intracellular signalling cascade. Polymorphism in the MUC1 gene has been identified in gastric cancer patients and may have a prospective role in the stratification of high-risk subjects. The MUC1 gene also mediates resistance to the recombinant HER2/neu antibody trastuzumab. Future research efforts will examine targeting MUC1 for therapeutic purposes.