Antioxidant pre-treatment prevents omeprazole-induced toxicity in an in vitro model of infectious gastritis

Omeprazole is a mainstay of therapy for gastroesophageal reflux disease (GERD) and gastritis, and is increasingly used as an over-the-counter remedy for dyspepsia. Omeprazole acts by selectively oxidizing thiol targets in the gastric proton pump, but it also appears to be toxic to the gastric mucosa. We hypothesized that omeprazole toxicity is due to non-specific oxidation of cell structures other than the proton pump, and tested the efficacy of antioxidants to prevent omeprazole-induced toxicity in isolated rabbit gastric glands. Toxicity was measured by uptake and converstion of calcein-AM, following three hours of exposure to omeprazole and a non-selective thiol-oxidant, monochloramine. Intracellular concentration of Zn(2+) and the capacity to maintain luminal acidity were monitored using the fluorescent reporters fluozin-3 and Lysosensor DND-160, respectively. Both omeprazole and monochloramine caused marked reduction in cell viability. The toxicity of omeprazole was independent of monochloramine toxicity. The thiol reducing agent dithiothreitol protected gastric glands from injury. The oxidant scavenger Vitamin C also protected, and did not impair the anti-secretory effects of omeprazole. Thus, omeprazole toxicity appears to be oxidative and preventable with antioxidant therapy, including Vitamin C. Vitamin C may be a safe and efficacious addition to treatments requiring the use of PPIs.

An easy method to identify parietal cells in gastric biopsies

BACKGROUND

Sections from gastric biopsies are usually stained with hematoxylin and eosin (H&E), a stain that is not optimal for the recognition of many parietal cells. This paper describes a more suitable routine stain to identify parietal cells.

PATIENTS AND METHODS

Nineteen sets of gastric biopsies were consecutively stained with H&E and with modified Giemsa. Giemsa-stained fundic biopsies showed a parietal cell band intercalated between the fovelar epithelium and the chief glands. The continuity of this band was studied at x4 magnification and its thickness in one well-oriented field at x10 magnification.

RESULTS

A distinct, continuous parietal cell band was recorded in fundic biopsies exhibiting normal mucosa, acute gastritis or chronic gastritis without glandular atrophy (Group A). A discontinuous or lack of parietal cell band was found in fundic biopsies exhibiting chronic gastritis with glandular atrophy or with intestinal metaplasia (Group B). The ratio of parietal cell band/total mucosal thickness ranged between 0.30 and 0.40 in Group A and between 0 and 0.25 in Group B.

CONCLUSION

A parietal cell band was readily demonstrated in sections from gastric biopsies stained with Giemsa, but not in those stained with H&E. Discontinuity with reduced or absent band was recorded in gastric diseases characterised by a decrease of the parietal cell population.

The gastric mucosa in portal hypertension: structural and ultrastructural observations

The gastric mucosal lesions represent a frequent cause of hemorrhage in the portal hypertension (PHG) and in the hepatic cirrhosis. This study was undertaken to assess the structural and ultra structural modifications in the intimal lamina of the stomach in this pathology. The cells of mucosa show graded alterative transformations. In the gastric mucosa, some of the chief (enzymatic) cells present a quasi-normal histological organization; others increased alterations such as irregular and heterochromatic nuclei, fewer cytoplasm organelles, numerous clear vesicles and heterogeneous lysosomes. The parietal (oxyntic) cells show in their apical cytoplasm wide dilatations of the intracellular canalicles, vesicles, a reduced number of organelles and irregular nuclei. The enteroendocrine cells (APUD) present an increased number of granules and organelles in the cytoplasm. The connective inter-glandular tissue contains active fibroblasts, micro inflammatory zones, blood vessels with hypertrophied endothelium, irregular and dilated lumen. Subsequent to these alterations in the structures of the gastric mucosa in portal hypertension, the function of synthesis/excretion of the pepsinogen, lipase, hydrochloric acid, intrinsic factor, serotonin, etc. are affected.

Oxyntic atrophy, metaplasia, and gastric cancer

Gastric carcinogenesis involves the loss of parietal cells (oxyntic atrophy) and subsequent replacement of the normal gastric lineages with metaplastic cells. In humans, two metaplastic lineages develop as sequelae of chronic Helicobacter pylori infection: intestinal metaplasia and spasmolytic polypeptide-expressing metaplasia (SPEM). Mouse models of both chronic Helicobacter infection and acute pharmacological oxyntic atrophy have led to the discovery that SPEM arises from transdifferentiation of mature chief cells. The presence of inflammation promotes the expansion of SPEM in mice. Furthermore, studies in Mongolian gerbils as well as increasing evidence from human studies indicate that SPEM likely represents a precursor for the development of intestinal metaplasia. These findings suggest that loss of parietal cells, augmented by chronic inflammation, leads to a cascade of metaplastic events. Identification of specific biomarkers for SPEM and intestinal metaplasia hold promise for providing both early detection of preneoplasia and information on prognostic outcome following curative resection.

Pernicious anemia in a patient with Type 1 diabetes mellitus and alopecia areata universalis

A 27-year-old male, who had developed diabetes mellitus type 1 (DMT1) since the age of eighteen and alopecia areata universalis nine months later, attended the outpatient clinics complaining of general fatigue and shortness of breath. A Schilling test was indicative of pernicious anemia. Antigastric parietal cell (AGPA) and anti-intrinsic factor antibodies were positive, confirming diagnosis of pernicious anemia. Thyroid and Addison's disease were excluded. Gastroscopy revealed atrophic gastritis without any evidence of carcinoid tumors. The aim of this case, which, to our knowledge, is the first one to describe a correlation between diabetes mellitus Type 1 (DMT1), pernicious anaemia, and alopecia areata universalis, is to remind the clinician of the increased risk of pernicious anaemia and gastric carcinoids in DMT1 patients. Screening for AGPA followed by serum gastrin and vitamin B(12) levels constitute the most evidence-based diagnostic approach.

The Story So Far:Helicobacter Pyloriand Gastric Autoimmunity

The gastric mucosal pathogen Helicobacter pylori induces autoantibodies directed against the gastric proton pump H+,K+-ATPase in 20-30% of infected patients. The presence of these autoantibodies is associated with severity of gastritis, increased atrophy, and apoptosis in the corpus mucosa, and patients with these autoantibodies infected with H. pylori display histopathological and clinical features that are similar to those of autoimmune gastritis (AIG). This review will focus on the T helper cell responses, cytokines, and adhesion molecules involved in corpus mucosal atrophy in chronic H. pylori gastritis and in AIG, and the role of H. pylori in the onset of AIG.

Mechanisms of Gastric Mucosal Cell Loss In Autoimmune Gastritis

The causes of target cell death in organ-specific autoimmune diseases are not precisely known. In the case of EAG, parietal cell death depends on Th1 CD4 T cells and Fas/Fas-ligand, either through interaction between infiltrating CD4 T cells with gastric parietal cells that have upregulated Fas expression or through homotypic interactions between the parietal cells. TNF-alpha does not appear to have a role in this process. The accompanying loss of zymogenic cells is likely a consequence of the interruption of the normal developmental pathway in the gastric mucosa that follows the destruction of parietal cells in the gastric mucosa.

Alterations in gastric mucosal lineages before or after acute oxyntic atrophy in gastrin receptor and H2 histamine receptor-deficient mice

Spasmolytic polypeptide (SP/TFF2)-expressing metaplasia (SPEM) is induced by oxyntic atrophy and is known as a precancerous or paracancerous lesion. We seek to determine whether the gastrin receptor or H(2) histamine receptor influence the development of SPEM. DMP-777 was administered to gastrin receptor and/or H(2) receptor-deficient mice and wild-type mice. Gastric mucosal lineage changes were analyzed. The mucosa from double knockout mice and H(2) receptor knockout mice contained elevated numbers of dual TFF2 and intrinsic factor immunoreactive cells even before DMP-777 treatment. All genotypes of mice showed SPEM after 7-day treatment. In all types of knockout mice, the number of TFF2 immunoreactive cells remained elevated after cessation of treatment. The H(2) receptor and gastrin receptor do not affect emergence of SPEM. However, it is suggested that the absence of H(2) receptor signaling causes a delay in the maturation of chief cells from mucous neck cells.

Protective effects of DIDS against ethanol-induced gastric mucosal injury in rats

The compound 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) is an efficient anion exchanger inhibitor that can block the activities of anion exchanger 2 (AE2), which plays an indispensable role in gastric acid secretion. DIDS also has potent anti-oxidative and antiapoptosis activities. This study aimed to investigate the effect of DIDS on ethanol-induced mucosal damage in rats and to evaluate the underlying mechanisms that mediate the action of the compound. The rats received 1 ml of absolute ethanol or saline orally. DIDS [50 mg/kg intravenous (i.v.)] was given 5 min before ethanol administration. Gastric lesions were evaluated macroscopically, microscopically, and electron microscopically at 60 min after ethanol challenge. Gastric myeloperoxidase (MPO) activity, malonyldialdehyde (MDA) level, prostaglandin E2 (PGE2) synthesis, and cyclooxygenase-2 (COX-2) expression were assessed. For the evaluation of the effect of DIDS on gastric acid secretion, histamine-stimulatory gastric acid secretion was examined with or without pretreatment of DIDS (50 mg/kg; i.v.). Ethanol-induced gastric lesions were characterized by increasing gastric MDA level, MPO activity, and COX-2 expression, and decreasing PGE2 synthesis. It was found that DIDS significantly reduced the extent of gastric mucosal damage and reversed tissue MDA level and MPO activity. DIDS further enhanced the expression of COX-2 and reversed the decrease of PGE2. Our results suggested that DIDS is beneficial in rat model of gastric injury through mechanisms that involve inhibiting inflammatory cell infiltration and lipid peroxidation and up-regulating the COX-2/PGE2 pathway.

[Signal transudation pathways in parietal cells of the gastric mucosa in experimental stomach ulcer]

The goal of the presented work was the research of signal transduction mechanism in the rat gastric parietal cells under stomach ulcer conditions. In these cells activation of adenylate cyclase (increase of cAMP level and proteinkinase A activity) and phosphoinositide (increases [Ca2+]i; cGMP and phoshatidylinocitole levels; proteinkinase C, proteinkinase G, and calmodulin-dependent-proteinkinase activity) of signals pathway was shown. An increase of plasma membrane phospholipids (PC, PS, PE, PI, LPC) level was shown. Under conditions of influence of the stress factor the membran enzymes activity (H+, K+ -ATPase, 5'-AMPase, Na+, K+ -ATPase, Ca2+, Mg2+ -ATPase and H+, K+ -ATPase) was considerably increased. The intensification of lipid peroxidation processes in rats was demonstrated.

Gastric endocrine tumors type I: treatment with long-acting somatostatin analogs

Gastric endocrine tumors associated with autoimmune chronic atrophic gastritis (gastric carcinoid type I) are almost exclusively benign lesions with little risk of deep invasion of the gastric parietal wall. For this reason, the role of octreotide in the treatment of these neoplastic lesions is controversial. Nine patients with more than five type I gastric endocrine tumors each <1 cm in size, without invasion of the muscularis propria and with Ki-67 index lower than 3%, were treated with long-acting somatostatin analogs for 12 months. After 6 months and again after 12 months, all the patients underwent upper gastrointestinal (GI) endoscopy with multiple biopsies. The plasma chromogranin A (CgA) levels and the gastrin levels in the serum were also determined. In all patients, the gastric neoplastic lesions disappeared after 12 months of somatostatin analog therapy. We also observed a significant reduction of CgA and gastrin levels at 6 and at 12 months of therapy as compared with the baseline values. We demonstrate that somatostatin analog treatment provokes the pathological regression of type I gastric carcinoids. This therapeutic approach should be considered as a valid option in selected patients with multiple type I gastric endocrine tumors.

Reduced Shh expression in TFF2-overexpressing lesions of the gastric fundus under hypochlorhydric conditions

Expression of sonic hedgehog (Shh), a morphogen for the gastric fundic glands, is reduced in the atrophic mucosa that develops in association with Helicobacter pylori infection, resulting in impaired differentiation of the fundic gland cells, increased expression of trefoil factor family 2 (TFF2) and the formation of spasmolytic polypeptide (SP)-expressing metaplasia (SPEM), a preneoplastic lesion. However, it is still unresolved whether H. pylori-induced inflammation and the resultant reduction in parietal cell number or reduced parietal cell function per se reduces Shh expression. The present study was designed to clarify the expression of Shh and TFF2 in the context of parietal cell dysfunction in the absence of inflammation, using histamine H(2) receptor-knockout (H(2)R-null) mice and an acid exposure model. Age-matched H(2)R-null mice and wild-type (WT) mice were used. The expression of Shh and TFF2 mRNA was quantified by quantitative RT-PCR. Immunohistochemistry was also performed to detect the expression of Shh, TFF2 and cell markers. To study the effects of acid exposure, HCl solution was administered to the animals. The H(2)R-null mice exhibited higher gastric pH, increased TFF2 expression and reduced Shh expression. Impaired mucous neck-to-zymogenic cell differentiation was observed in the H(2)R-null mice. Furthermore, Shh expression increased in the presence of gastric acid and showed a significant correlation with gastric surface pH. In conclusion, our results suggest that persistent parietal cell dysfunction alone (suppressed gastric acid secretion), in the absence of inflammation or parietal cell loss caused by H. pylori infection, may be sufficient to down-regulate Shh expression in TFF2-overexpressing preneoplastic lesions of the gastric fundus. Since exposure to acid restored fundic Shh expression, appropriate gastric acid secretion may play an important role in the morphogen dynamics involved in the maintenance of gastric fundic gland homeostasis.

Histopathology of columnar-lined esophagus in patients with gastroesophageal reflux disease

BACKGROUND AND AIMS

The question of whether an endoscopically normal-appearing esophagogastric junction should be biopsied in patients with gastroesophageal reflux disease is controversial. We have addressed this issue using endoscopy and histopathology.

METHODS

A total of 114 consecutive patients (58 males) with symptoms of gastroesophageal reflux disease prospectively underwent endoscopy, including biopsy sampling from the esophagogastric junction. Endoscopically visible columnar-lined esophagus was defined by the presence of gastric-type mucosa above the level of the rise of the gastric folds. Histopathology was conducted using the Paull-Chandrasoma classification.

RESULTS

Of the 114 patients, 85 (74.6%) had endoscopically visible columnar-lined esophagus of length < or =0.5 cm (n = 82), 1 cm (n = 2) and 7 cm (n = 1); 29 patients (25.4%) had a normal endoscopic junction. All patients had histopathologic columnar-lined esophagus. Intestinal metaplasia and low-grade dysplasia was identified in 26 (22.8%) and 5 (4.4%) individuals, respectively, and was not statistically different in endoscopically normal vs. abnormal junction (P = 0.408 for intestinal metaplasia, P = 0.775 for low grade dysplasia). Intestinal metaplasia was independent from endoscopic esophagitis (P = 0.398) and hiatal hernia (P = 0.405).

CONCLUSIONS

Columnar-lined esophagus cannot be excluded by endoscopy. In patients with gastroesophageal reflux disease, biopsy sampling of normal-appearing junction is recommended for histopathologic exclusion of intestinal metaplasia and low-grade dysplasia.

Incomplete synthesis of the Sda/Cad blood group carbohydrate in gastrointestinal cancer

Cancer-associated changes in cell surface carbohydrates, including incomplete synthesis of normal carbohydrate epitopes, strongly affect malignant and metastatic potential. Here, we report that compensating for the cancer-associated loss of a single glycosyltransferase, beta1,4N-acetylgalactosaminyltransferase T2, dramatically decreased cell surface expression of both E-selectin ligands (sialyl Lewis(x) and sialyl Lewis(a)). This modification was associated with elevated expression of the Sd(a) carbohydrate determinant, which is expressed in normal gastrointestinal mucosa and is strikingly downregulated in cancer tissues. Loss of E-selectin ligands resulted in decreased adhesion of cancer cells to activated human endothelial cells in vitro and eventually suppressed metastatic potential in vivo.

Functional role of bone morphogenetic protein-4 in isolated canine parietal cells

Bone morphogenetic protein (BMP)-4 is an important regulator of cellular growth and differentiation. Expression of BMP-4 has been documented in the gastric mucosa. We reported that incubation of canine parietal cells with EGF for 72 h induced both parietal cell morphological transformation and inhibition of H(+)/K(+)-ATPase gene expression through MAPK-dependent mechanisms. We explored the role of BMP-4 in parietal cell maturation and differentiation. Moreover, we investigated if BMP-4 modulates the actions of EGF in parietal cells. H(+)/K(+)-ATPase gene expression was examined by Northern blots and quantitative RT-PCR. Acid production was assessed by measuring the uptake of [(14)C]aminopyrine. Parietal cell apoptosis was quantitated by Western blots with anti-cleaved caspase 3 antibodies and by counting the numbers of fragmented, propidium iodide-stained nuclei. MAPK activation and Smad1 phosphorylation were measured by Western blots with anti-phospho-MAPK and anti-phospho-Smad1 antibodies. Parietal cell morphology was examined by immunohistochemical staining of cells with anti-H(+)/K(+)-ATPase alpha-subunit antibodies. BMP-4 stimulated Smad1 phosphorylation and induced H(+)/K(+)-ATPase gene expression. BMP-4 attenuated EGF-mediated inhibition of H(+)/K(+)-ATPase gene expression and blocked EGF induction of both parietal cell morphological transformation and MAPK activation. Incubation of cells with BMP-4 enhanced histamine-stimulated [(14)C]aminopyrine uptake. BMP-4 had no effect on parietal cell apoptosis, whereas TGF-beta stimulated caspase-3 activation and nuclear fragmentation. In conclusion, BMP-4 promotes the induction and maintenance of a differentiated parietal cell phenotype. These findings may provide new clues for a better understanding of the mechanisms that regulate gastric epithelial cell growth and differentiation.

The histological examination of Mus musculus' stomach which was exposed to hunger and thirst stress: a study with light microscope

In this study, the histological changes observed in Mus musculus' stomach mucosa which was exposed to hunger and thirst were examined. Pieces from chest and stomach cavities were taken in the 1st, 2nd, 3rd, 4th and 5th days following last feeding. These tissue specimens were fixed by using 10% neutral formalin which was compressed. After routine tissue checks, the tissue pieces were sunk into paraffin and some blocs were prepared. With the aim to examine histological structures of the pieces taken, they were colored with Hematoxylin and Eosin (H and E). An increase in the number of blood cells taken part in stomach tissue was observed in the first twenty four hours. A widening in glandular epithelium lumen was seen after two days. A tendency to slim was observed in mucosa layer of the surface and glandular lumen during hunger. In the stomach mucosa, structural changes were caused by hunger and thirst. It was found that these changes were in direct proportion with hunger and thirst duration.

Potentiation of oxyntic atrophy-induced gastric metaplasia in amphiregulin-deficient mice

BACKGROUND & AIMS

The loss of parietal cells from the gastric mucosa (oxyntic atrophy) is a critical step in the pathogenesis of chronic gastritis and gastric adenocarcinoma. Parietal cells are known to secrete epidermal growth factor receptor (EGFR) ligands, which are critical regulators of differentiation in the gastric mucosa. Although all of the actions of EGFR ligands are mediated through a common EGFR protein, individual ligands may produce different physiologic responses. Previous investigations have suggested that a deficit in EGFR signaling in waved-2 mice accelerates the emergence of metaplasia after induction of acute oxyntic atrophy. We sought to determine whether specific EGFR ligands regulate the metaplastic response to oxyntic atrophy.

METHODS

To induce spasmolytic polypeptide-expressing metaplasia (SPEM), amphiregulin (AR) and transforming growth factor-alpha-deficient mice and their wild-type littermates were treated with DMP-777 for 0-14 days and for 14 days followed by 14 days of recovery off drug. We evaluated the gastric mucosal response to oxyntic atrophy using cell lineage-specific markers.

RESULTS

Although loss of transforming growth factor-alpha did not influence the induction of SPEM, loss of AR caused an acceleration and amplification in the induction of SPEM after acute oxyntic atrophy. Trefoil factor family 2/spasmolytic polypeptide and intrinsic factor dual-immunostaining cells significantly increased in the SPEM of AR-deficient mice. At the bases of glands, intrinsic factor immunoreactive cells also were costained for 5-bromo-2'-deoxyuridine, suggesting their re-entry into the cell cycle.

CONCLUSIONS

The absence of AR promoted the rapid emergence of SPEM in response to oxyntic atrophy.

Investigations proposed to accurately classify chronic gastritis

Patients of chronic gastritis should be investigated with gastric mucosal biopsy, parietal cell antibody, intrinsic factor antibody, Helicobacter pylori antibody, urea breath test or faecal antigen test for Helicobacter pylori, to accurately classify them. The results of these tests will indicate Helicobacter pylori infection (present or past), the role of hereditary factor (intrinsic factor antibody present or absent) and the success or failure of Helicobacter pylori eradication treatment.

Discovery of (R)-9-ethyl-1,3,4,10b-tetrahydro-7-trifluoromethylpyrazino[2,1-a]isoindol- 6(2H)-one, a selective, orally active agonist of the 5-HT(2C) receptor

Robust pharmaceutical treatment of obesity has been limited by the undesirable side-effect profile of currently marketed therapies. This paper describes the synthesis and optimization of a new class of pyrazinoisoindolone-containing, selective 5-HT2C agonists as antiobesity agents. Key to optimization of the pyrazinoisoindolone core was the identification of the appropriate substitution pattern and functional groups which led to the discovery of (R)-9-ethyl-1,3,4,10b-tetrahydro-7-trifluoromethylpyrazino[2,1-a]isoindol-6(2H)-one (58), a 5-HT2C agonist with >300-fold functional selectivity over 5-HT2B and >70-fold functional selectivity over 5-HT2A. Oral dosing of 58 reduced food intake in an acute rat feeding model, which could be completely reversed by a selective 5-HT2C antagonist and caused a reduction in body weight gain in a 4-day rat model.

Differentiation of the gastric mucosa III. Animal models of oxyntic atrophy and metaplasia

Gastric cancer in humans arises in the setting of oxyntic atrophy (parietal cell loss) and attendant hyperplastic and metaplastic lineage changes within the gastric mucosa. Helicobacter infection in mice and humans leads to spasmolytic polypeptide-expressing metaplasia (SPEM). In a number of mouse models, SPEM arises after oxyntic atrophy. In mice treated with the parietal cell toxic protonophore DMP-777, SPEM appears to arise from the transdifferentiation of chief cells. These results support the concept that intrinsic mucosal influences regulate and modulate the appearance of gastric metaplasia even in the absence of significant inflammation, whereas chronic inflammation is required for the further neoplastic transition.

The effect of Helicobacter felis and Helicobacter bizzozeronii on the gastric mucosa in Mongolian gerbils: a sequential pathological study

In contrast to Helicobacter(H.) pylori, little is known about the pathogenic mechanisms of gastric non-H. pylori Helicobacter species. Mongolian gerbils were inoculated intragastrically with H. felis or H. bizzozeronii and killed at different timepoints post-inoculation (p.i.), stomach tissue being taken for light and transmission electron microscopy (TEM) and polymerase chain reaction (PCR) analysis. Parietal cells (PCs), apoptosis, cell proliferation and nuclear factor-kappaB (NF-kappaB) activation were "visualized" immunohistochemically. Inflammation consisted of neutrophilic granulocytes, mainly in the antrum, and lymphocytic infiltrates around the limiting ridge and throughout the stomach mucosa and submucosa. From day 11 p.i. onwards, H. felis-inoculated animals showed moderate to severe loss of PCs extending from the limiting ridge into the fundus. Apoptotic cells, spiral bacteria, cell proliferation, and NF-kappaB activation were detected at the transition zone between affected and normal PCs. TEM revealed interaction of H. felis flagella with PCs and chief cells. Moreover, H. felis was seen in proximity to, and inside, necrotic cells. At 10 weeks p.i., some H. felis-infected gerbils showed complete loss of fundic glands, and mucous metaplasia of the epithelium. H. bizzozeronii, which made no flagellar contact with epithelial cells, was associated with only mild PC loss. The mechanism by which H. felis induces PC necrosis and apoptosis remains unclear. The observed flagellar contact and NF-kappaB activation may play an important role in H. felis-associated inflammation.