Mechanism of gastric mucosal proliferation induced by gastrin

Correctly identifying the cells of origin is essential for tailoring treatment and understanding the emergence of cancer stem cells and late metastases

Malignancy manifests itself by deregulated growth and the ability to invade surrounding tissues or metastasize to other organs. These properties are due to genetic and/or epigenetic changes, most often mutations. Many aspects of carcinogenesis are known, but the cell of origin has been insufficiently focused on, which is unfortunate since the regulation of its growth is essential to understand the carcinogenic process and guide treatment. Similarly, the concept of cancer stem cells as cells having the ability to stop proliferation and rest in a state of dormancy and being resistant to cytotoxic drugs before "waking up" and become a highly malignant tumor recurrence, is not fully understood. Some tumors may recur after decades, a phenomenon probably also connected to cancer stem cells. The present review shows that many of these questions are related to the cell of origin as differentiated cells being long-term stimulated to proliferation.

Randomised clinical trial: 3-year interim analysis results of the VISION trial to evaluate the long-term safety of vonoprazan as maintenance treatment in patients with erosive oesophagitis

BACKGROUND

VISION is a randomised, phase 4, open-label, parallel-group, multicentre study conducted in 33 centres in Japan. The aim of this study was to assess the long-term safety of vonoprazan for maintenance treatment of healed erosive oesophagitis versus lansoprazole.

METHODS

Patients with endoscopically diagnosed erosive oesophagitis were randomised 2:1 to once-daily vonoprazan 20 mg or lansoprazole 30 mg, for a 4- to 8-week healing phase. Patients with endoscopically confirmed healing entered a 260-week maintenance phase with a once-daily starting dose of vonoprazan 10 mg or lansoprazole 15 mg. Primary endpoint was change in gastric mucosal histopathology.

RESULTS

Of 208 patients (vonoprazan, n = 139; lansoprazole, n = 69) entering the healing phase, 202 entered the maintenance phase (vonoprazan, n = 135; lansoprazole, n = 67). At 3 years, 109 vonoprazan-treated and 58 lansoprazole-treated patients remained on treatment. Histopathological evaluation of gastric mucosa showed that hyperplasia of parietal, foveolar and G cells was more common with vonoprazan than lansoprazole at week 156 of the maintenance phase. There was no marked increase in the occurrence of parietal, foveolar and G cell hyperplasia among patients in the vonoprazan group from week 48 to week 156. Histopathological evaluation of the gastric mucosa also showed no neoplastic changes in either group. No new safety issues were identified.

CONCLUSIONS

In this interim analysis of VISION, no new safety concerns were identified in Japanese patients with healed erosive oesophagitis receiving vonoprazan or lansoprazole as maintenance treatment for 3 years. (CT.gov identifier: NCT02679508; JapicCTI-163153; Japan Registry of Clinical Trials: jRCTs031180040).

Vitamin D Is Necessary for Murine Gastric Epithelial Homeostasis

Unlike other organs, the importance of VD in a normal stomach is unknown. This study focuses on understanding the physiological role of vitamin D in gastric epithelial homeostasis. C57BL/6J mice were divided into three groups that were either fed a standard diet and kept in normal light/dark cycles (SDL), fed a standard diet but kept in the dark (SDD) or fed a vitamin D-deficient diet and kept in the dark (VDD). After 3 months, sera were collected to measure vitamin D levels by LC-MS/MS, gastric tissues were collected for immunohistochemical and gene expression analyses and gastric contents were collected to measure acid levels. The VDD group showed a significant decrease in the acid-secreting parietal cell-specific genes Atp4a and Atp4b when compared with the controls. This reduction was associated with an increased expression of an antral gastrin hormone. VDD gastric tissues also showed a high proliferation rate compared with SDL and SDD using an anti-BrdU antibody. This study indicates the requirement for normal vitamin D levels for proper parietal cell functions.

Discovery of HB-EGF binding peptides and their functional characterization in ovarian cancer cell lines

Ovarian cancer is one of the most frequent causes of cancer death among all gynecologic cancers. Though standard therapy often results in temporary clinical remission, most patients suffer from recurrence and metastasis of ovarian cancer, which highlights the need for developing new therapeutic agents targeting specific molecules. Previous studies have demonstrated that the native ligand of epidermal growth factor receptor (EGFR) and ErbB4, heparin-binding EGF-like growth factor (HB-EGF), plays a critical role in the progression of ovarian cancer and is associated with prognosis of ovarian cancer. In the current study, we tried to develop a peptide-based treatment for ovarian cancer by targeting HB-EGF. After the functions of HB-EGF in promoting migration and invasion of SKOV3 and HO-8910 cells were confirmed, phage display was used to discover peptides binding to HB-EGF. Two peptides, no. 7 and no. 29 were found mildly binding to HB-EGF. Then the effects of these peptides on HB-EGF functions were examined and both peptides no. 7 and no. 29 were found indeed inhibiting the functions of HB-EGF in promoting migration and invasion of SKOV3 and HO-8910 cells in vitro. Further mechanism investigation showed that peptides no. 7 and no. 29 inhibited HB-EGF-promoted cell migration and invasion through attenuating activation of the EGFR signaling pathway manifested by decreased p-Erk1/2 and Snail levels. More importantly, peptides no. 7 and no. 29 showed strong activities in inhibiting migration of SKOV3 cells in vivo. These results provide a proof of concept method for developing novel peptide drugs to combat ovarian cancer through interfering with HB-EGF mediated signaling pathways.

Gastrin and Gastric Cancer

Gastric cancer is the third leading cause of cancer-related mortality worldwide. Despite progress in understanding its development, challenges with treatment remain. Gastrin, a peptide hormone, is trophic for normal gastrointestinal epithelium. Gastrin also has been shown to play an important role in the stimulation of growth of several gastrointestinal cancers including gastric cancer. We sought to review the role of gastrin and its pathway in gastric cancer and its potential as a therapeutic target in the management of gastric cancer. In the normal adult stomach, gastrin is synthesized in the G cells of the antrum; however, gastrin expression also is found in many gastric adenocarcinomas of the stomach corpus. Gastrin's actions are mediated through the G-protein-coupled receptor cholecystokinin-B (CCK-B) on parietal and enterochromaffin cells of the gastric body. Gastrin blood levels are increased in subjects with type A atrophic gastritis and in those taking high doses of daily proton pump inhibitors for acid reflux disease. In experimental models, proton pump inhibitor-induced hypergastrinemia and infection with Helicobacter pylori increase the risk of gastric cancer. Understanding the gastrin:CCK-B signaling pathway has led to therapeutic strategies to treat gastric cancer by either targeting the CCK-B receptor with small-molecule antagonists or targeting the peptide with immune-based therapies. In this review, we discuss the role of gastrin in gastric adenocarcinoma, and strategies to block its effects to treat those with unresectable gastric cancer.

A highly acid-resistant novel strain of Lactobacillus johnsonii No. 1088 has antibacterial activity, including that against Helicobacter pylori, and inhibits gastrin-mediated acid production in mice

A novel strain of Lactobacillus johnsonii No. 1088 was isolated from the gastric juice of a healthy Japanese male volunteer, and characterized for its effectiveness in the stomach environment. Lactobacillus johnsonii No. 1088 was found to have the strongest acid resistance among several lactobacilli examined (>10% of cells survived at pH 1.0 after 2 h), and such a high acid resistance property was a specific characteristic of this strain of L. johnsonii. When cultured with various virulent bacteria, L. johnsonii No. 1088 inhibited the growth of Helicobacter pylori, Escherichia coli O-157, Salmonella Typhimurium, and Clostridium difficile, in which case its effectiveness was more potent than that of a type strain of L. johnsonii, JCM2012. In addition to its effect in vitro, L. johnsonii No. 1088 inhibited the growth of H. pylori in human intestinal microbiota-associated mice in both its live and lyophilized forms. Moreover, L. johnsonii No. 1088 suppressed gastric acid secretion in mice via decreasing the number of gastrin-positive cells in the stomach. These results taken together suggest that L. johnsonii No. 1088 is a unique lactobacillus having properties beneficial for supporting H. pylori eradication by triple therapy including the use of a proton pump inhibitor (PPI) and also for prophylaxis of gastroesophageal reflux disease possibly caused after H. pylori eradication as a side effect of PPI.

Gastrin upregulates the prosurvival factor secretory clusterin in adenocarcinoma cells and in oxyntic mucosa of hypergastrinemic rats

We show that the gastric hormone gastrin induces the expression of the prosurvival secretory clusterin (sCLU) in rat adenocarcinoma cells. Clusterin mRNA was still upregulated in the presence of the protein synthesis inhibitor cycloheximide, although at a lower level. This indicates that gastrin induces clusterin transcription independently of de novo protein synthesis but requires de novo protein synthesis of signal transduction pathway components to achieve maximal expression level. Luciferase reporter assay indicates that the AP-1 transcription factor complex is involved in gastrin-mediated activation of the clusterin promoter. Gastrin-induced clusterin expression and subsequent secretion is dependent on sustained treatment, because removal of gastrin after 1-2 h abolished the response. Neutralization of secreted clusterin by a specific antibody abolished the antiapoptotic effect of gastrin on serum starvation-induced apoptosis, suggesting that extracellular clusterin is involved in gastrin-mediated inhibition of apoptosis. The clusterin response to gastrin was validated in vivo in hypergastrinemic rats, showing increased clusterin expression in the oxyntic mucosa, as well as higher levels of clusterin in plasma. In normal rat oxyntic mucosa, clusterin protein was strongly expressed in chromogranin A-immunoreactive neuroendocrine cells, of which the main cell type was the histidine decarboxylase-immunoreactive enterochromaffin-like (ECL) cell. The association of clusterin with neuroendocrine differentiation was further confirmed in human gastric ECL carcinoids. Interestingly, in hypergastrinemic rats, clusterin-immunoreactive cells formed distinct groups of diverse cells at the base of many glands. Our results suggest that clusterin may contribute to gastrin's growth-promoting effect on the oxyntic mucosa.

Pancreatic stone protein/regenerating protein family in pancreatic and gastrointestinal diseases

Pancreatic stone protein (PSP; reported in 1979), pancreatitis-associated protein (PAP; 1984) and regenerating protein (Reg I; 1988) were discovered independently in the fields of the exocrine (pancreatitis) and endocrine (diabetes) pancreas. Subsequent analysis revealed that PSP and Reg I are identical and PAP belongs to the same protein family. PSP/Reg I and PAP share a selective and specific trypsin cleavage site and result in insoluble fibrils (PTP, PATP). Search for a functional role of PSP had led to the idea that it might serve as an inhibitor in pancreatic stone formation and PSP was renamed lithostathine. Inhibitory effects of lithostathine in stone formation have been questioned. Evidence so far obtained can support a lithogenic role rather than a lithostatic role of PSP. PAP and its isoforms have been investigated mainly regarding responses to inflammation and stress. Reg I and its isoforms have been examined on regeneration, growth and mitogenesis in gastrointestinal neoplastic diseases as well as diabetes. Evidence obtained can be applied in the prediction of prognosis and therapy for inflammatory and neoplastic diseases.

Exacerbation of indomethacin-induced small intestinal injuries in Reg I-knockout mice

Nonsteroidal anti-inflammatory drug (NSAID)-induced small intestinal injuries are serious clinical events and a successful therapeutic strategy is difficult. Regenerating gene (Reg) I protein functions as a regulator of cell proliferation and maintains intercellular integrity in the small intestine. The aim of this study was to evaluate the role of Reg I in NSAID-induced small intestinal injuries. First, to examine the effect of Reg I deficiency on such injuries, indomethacin, a widely used NSAID, was injected subcutaneously into 10-wk-old male Reg I-knockout (Reg I(-/-)) and wild-type (Reg I(+/+)) mice twice with an interval of 24 h, after which the mice were euthanized. Small intestinal injuries were assessed by gross findings, histopathology, and contents of IL-1beta and MPO in the experimental tissues. Next, we investigated the therapeutic potential of Reg I in indomethacin-induced small intestinal injuries. Recombinant Reg I protein (rReg I) was administered to 10-wk-old male ICR mice, then indomethacin was administered 6 h using the same protocol as noted above, after which small intestinal injuries were assessed after euthanasia. Our results showed that Reg I(-/-) mice had a greater number of severe small intestinal lesions after indomethacin administration. Histological examinations of the small intestines from those mice revealed deep ulcers with prominent inflammatory cell infiltration, whereas the mucosal content of proinflammatory agents was also significantly increased. In addition, rReg I administration inhibited indomethacin-induced small intestinal injuries in ICR mice. In conclusion, Reg I may be useful as a therapeutic agent in NSAID-induced small intestinal injuries.

Loss of RegI in conjunction with gastrin deficiency in mice facilitates efficient gastric ulcer healing but is dispensable for hyperplasia and tumourigenesis

RegI (Regenerating islet derived-1) was originally characterized as a growth factor involved in pancreatic islet cell regeneration. It is also considered a gastrointestinal mitogen as its expression is increased during pathologies involving aberrant cell proliferation that can lead to neoplasia. However, the absolute requirement for RegI to directly stimulate gastric mucosal cell proliferation in vivo requires further investigation. We used RegI-deficient mice to determine the requirement for RegI in normal gastric mucosal development, wound healing, hyperplasia and tumourigenesis. We found that epithelial repair of acetic acid ulcers in compound mutant RegI/gastrin-deficient mice was significantly reduced compared to wild type, RegI-deficient or gastrin-deficient mice. In contrast, RegI was dispensable for normal gastric mucosal development, hyperplasia in HKbeta-deficient mice and tumourigenesis in gp130(F/F) mice. Although RegI was not required for proliferation in these pathological models, expression of multiple Reg family members were increased during gp130(F/F) tumourigenesis. Interestingly, loss of RegI in gp130(F/F) mice resulted in decreased expression of other Reg family members. Our results indicate that RegI and gastrin may synergistically regulate gastric mucosal proliferation during certain pathological settings like wound healing while gastric epithelial proliferation in other pathologies may require coordinated expression of multiple Reg genes.

Gastrin - active participant or bystander in gastric carcinogenesis?

Gastrin is a pro-proliferative, anti-apoptotic hormone with a central role in acid secretion in the gastric mucosa and a long-standing association with malignant progression in transgenic mouse models. However, its exact role in human gastric malignancy requires further validation. Gastrin expression is tightly regulated by two closely associated hormones, somatostatin and gastrin-releasing peptide, and aspects of their interaction may be deregulated during progression to gastric adenocarcinoma. Furthermore, agonists and antagonists of the receptors for all three hormones have shown modest clinical efficacy against gastric adenocarcinoma, which might provide useful information on the future combined use of these agents.

Gastric inflammation, metaplasia, and tumor development in gastrin-deficient mice

BACKGROUND & AIMS

Gastrin deficiency and proton pump inhibitor treatment cause achlorhydria, which predisposes to disease. To elucidate the underlying molecular biology, we examined the changes in gastric gene expression in both types of achlorhydria. We also explored the associated changes in the gastric microflora and the long-term consequences of gastrin-deficient achlorhydria.

METHODS

Expression profiles were generated from gastric RNA from wild-type mice, gastrin knockout (KO) mice, gastrin KO mice after 1 week of gastrin infusion, and wild-type mice treated for 1 month with a proton pump inhibitor. The results were confirmed using real-time polymerase chain reaction and immunohistochemistry. Selective media were used to characterize the gastric microflora.

RESULTS

The number of gastric bacteria was increased in both gastrin KO and PPI-treated mice. The expression profiles revealed activation of immune defense genes, interferon-regulated response genes, and intestinal metaplasia of the gastric mucosa. In young gastrin-deficient mice, gastrin infusions reversed the changes. Over time, the changes accumulated, became irreversible, and progressed into metaplasia and polyp development. Finally, the study showed that gastrin regulated the expression of genes encoding extracellular matrix proteins.

CONCLUSIONS

Independently of gastrin, achlorhydria is associated with gastric bacterial overgrowth and intestinal gene expression patterns and is associated with predisposition to disease. Gastrin is therefore essential for prevention of gastric disease, mainly through control of acid secretion but to a lesser extent also through control of gastric gene expression. The gastrin-deficient mouse serves as a useful new model for gastric metaplasia and neoplasia.

Interleukin-8 regulates expression of Reg protein in Helicobacter pylori-infected gastric mucosa

BACKGROUND & AIM

Chronic inflammation induced by Helicobacter pylori infection is closely associated with epithelial cell proliferation and apoptosis, which are related to cellular turnover in gastric mucosa. Reg protein is a regenerating gene product and a potent growth factor for gastric mucosal cells, however, little is known regarding its association with the pathogenesis of H. pylori infection. The aim of this study was to investigate Reg protein production and its regulation in H. pylori-associated gastritis.

METHODS

Gastric fundic biopsy samples were taken from patients with and without H. pylori infection. In vivo expression of Reg protein was examined by Western blotting and immunohistochemistry methods. The effects of interleukin (IL)-8 on Reg protein expression and transcriptional activation of the Reg gene in ECC10 cells were investigated by Western blotting and luciferase assays, respectively.

RESULTS

Reg expression was found localized in the deeper part of gastric fundic glands and clearly shown in chromogranin A-positive cells in the gastric corpus. Semiquantitative immunohistochemistry and Western blotting results for Reg expression were significantly associated with polymorphonuclear neutrophil activity and chronic inflammation of gastric mucosa. IL-8 production in the gastric mucosa was significantly augmented by H. pylori infection, while IL-8 dose-dependently stimulated Reg protein production and Reg promoter activity in vitro in cultured ECC10 cells.

CONCLUSION

The present study showed for the first time that Reg protein may be a potent stimulator of gastric epithelial cells in H. pylori-infected human gastric mucosa stimulated by IL-8. Further, our findings provide evidence of a novel link between Reg protein and H. pylori infection, which may help explain the molecular mechanisms underlying H. pylori-associated diseases, including gastric cancer.

Growth factors associated with gastric mucosal hypertrophy in autoimmune gastritis

A prominent pathological feature of murine autoimmune gastritis is a pronounced mucosal hypertrophy. Here, we examined factors that may be responsible for inducing this hypertrophy. Because gastrin is known to be both an inducer of gastric mucosal cell proliferation and is elevated in autoimmune gastritis, mice deficient in gastrin were thymectomised at day 3 and assessed for autoimmune gastritis. Gastrin-deficient mice showed all the characteristic features of murine autoimmune gastritis, including gastric unit hypertrophy due to hyperproliferation and accumulation of immature epithelial cells, decreases in the number of zymogenic and parietal cells, and autoantibodies to the gastric H+/K+-ATPase. Hence, gastrin is not required for either the establishment of chronic gastritis or development of the typical pathological features of this disease. We also examined mRNA levels of a number of gastric mucosal growth factors in RNA samples from mice with hypertrophic autoimmune gastritis. Members of the Reg family, RegIIIbeta and RegIIIgamma, were greatly elevated in mice with hypertrophic gastritis, whereas RegI and amphiregulin (an EGF receptor ligand) were more modestly and/or inconsistently induced. These data demonstrate that induction of gastric mitogenic factors, such as members of the Reg family, can be achieved in inflammatory situations by gastrin-independent pathways. Members of the Reg family, in particular RegIIIbeta and RegIIIgamma, are good candidates to be involved in inducing the mucosal hyperproliferation in autoimmune gastritis. These findings are likely to be of relevance to other gastric inflammatory conditions.

An immunohistochemical study on the neuroendocrine system in the alimentary canal of the brown trout, Salmo trutta, L., 1758

Several neurohormonal peptides of the gastrointestinal system of fish have been revealed by immunohistochemical methods. Among salmonids, the rainbow trout, Oncorhynchus mykiss (Walbaum) is the most studied species, whereas the informations about other species of the taxonomic group are lacking. The regional distribution and relative densities of cells belonging to the neuroendocrine system have been in this paper demonstrated in the gut of the brown trout, Salmo trutta Linnaeus. In the gastric mucosa, endocrine cells were detected, which were immunoreactive to bombesin-, gastrin-, and secretin-antisera. Endocrine cells containing gastrin-, bombesin-, cholecystokinin-8-, glucagon-, and leptin-like immunoreactivities were present in the pyloric caeca and intestine. The pancreatic endocrine islets contained glucagon-, and, possibly, secretin-like-immunoreactive endocrine cells, as well as a contingent of galanin-like-immunoreactive nerve fibres. The exocrine pancreatic parenchyma showed bombesin-like-immunoreactive nerve fibres. Within the tested regulatory peptides, bombesin and leptin were observed in both endocrine cells and nerve cell bodies and fibres. Leptin was in addition detected in epithelial cells of the gastric glands. In the brown trout we have never observed any immunoreactivity to the VIP antiserum (either in the stomach or in the intestine). Some special structural patterns (in particular those ones related to galanin- and leptin-immunohistochemical data) have thus been detected for the first time in the brown trout, and provide further data for a better knowledge of gut morpho-functional aspects in this economically important fish.

Hypergastrinemia after Helicobacter pylori infection is associated with bacterial load and related inflammation of the oxyntic corpus mucosa

BACKGROUND AND AIM

Helicobacter pylori infection causes hypergastrinemia. This study aimed to determine the association between serum gastrin and the severity of H. pylori-related gastric histology.

METHODS

A total of 458 dyspeptic patients were included in this study after the absence of gastric malignancy was confirmed using endoscopy. The gastric specimens of each patient were collected from the antrum and corpus for the analysis of H. pylori-related histology changes by updated Sydney's system. Before endoscopy, the fasting blood samples were collected for gastrin analysis.

RESULTS

The H. pylori-infected patients had higher gastrin levels than those without infection (P = 0.01). Gastrin levels were related to H. pylori density and acute and chronic inflammation scores in the corpus mucosa (P < 0.05), but not in the antral mucosa (P = NS). Gastrin levels were also not related to the presence of gastric atrophy. Multivariate regression showed that the gastrin level was only related to acute corpus inflammation. However, in the patients without infection, the gastrin level was also associated with acute corpus inflammation. Nevertheless, the patients with denser H. pylori infection were more likely to have acute corpus gastritis than those with lighter H. pylori infection, and thus presented with higher gastrin levels (P < 0.05).

CONCLUSIONS

The increased level of gastrin of serum after H. pylori infection was associated with acute inflammation in the gastric corpus mucosa, but not in the antral mucosa. Denser H. pylori infection causes more severe corpus gastritis and thus may lead to a higher fasting level of gastrin of serum.

Gastric outlet obstruction as a consequence of a duodenal web masquerading as gastrinoma in an adult

We present the case of a 24-year-old man with recurrent peptic ulcers and hypergastrinemia, in whom a multidisciplinary investigation for gastrinoma revealed a duodenal web. The affected duodenal segment was excised, and a gastroduodenostomy with highly selective vagotomy was performed. Postoperative serum gastrin levels returned to the normal range over the next 6 weeks. Congenital duodenal anomalies are unusual causes of gastric outlet obstruction in adults. Chronic gastric outlet obstruction secondary to an adult duodenal web can induce neurohumoral changes in gastric function, which enhance both acid output and gastrin secretion. This case reminds clinicians to consider congenital anomalies in adults presenting with recurrent peptic ulcers and hypergastrinemia.

Effect of a gastrin/cholecystokinin B receptor antagonist, S-0509, on the omeprazole-induced proliferation of gastric mucosa in rats

Hypergastrinemia is known to cause hyperplasia of the gastric mucosa, especially in gastric enterochromaffinlike (ECL) cells. In some clinical conditions causing hypergastrinemia, such as long-term gastric-acid inhibition and gastric-mucosa atrophy, hyperplastic ECL cells may develop into gastric carcinoid tumors. A newly developed gastrin-receptor antagonist, S-0509, has been reported to block gastrin-induced stimulation of gastric-acid secretion. We therefore investigated whether S-0509 inhibits the omeprazole- and gastrin-stimulated hyperproliferation of gastric mucosa, especially of ECL cells. Daily administration of omeprazole and gastrin in male Sprague-Dawley rats induced marked hypergastrinemia and increased proliferation of gastric-mucosa cells. The numbers of ECL cells and of ECL cells producing messenger RNA for regenerating gene, a potent growth factor for gastric-mucosa cells, were also augmented by long-term administration of omeprazole and gastrin. Coadministration of S-0509 with omeprazole or gastrin almost completely inhibited the omeprazole- and gastrin-induced changes in gastric mucosa, including mucosal thickening and ECL hyperplasia. S-0509 did not induce gastric-mucosa atrophy, even when administered for as long as 4 weeks. In summary, we have found that a newly developed gastrin receptor antagonist, S-0509, inhibits omeprazole- and gastrin-induced mucosal hyperplasia, especially ECL-cell hyperplasia, in rats.

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Utilization of knockout mice to examine the potential role of gastric histamine H2-receptors in Menetrier's disease

Menetrier's disease is characterized by giant gastric folds with foveolar hyperplasia and cystic dilatation, hypoproteinemia, and enhanced mucus secretion. The etiology remains unresolved and an effective treatment has yet to be established. Here we show that histamine H(2)-receptor deficient mice developed gastric pathophysiological changes resembling Menetrier's disease for up to 17 months of observation. Mutant mice were found to have an increased stomach weight, enlarged gastric folds with cystic dilatation, hypergastrinemia, hypoalbuminemia, increased mucus secretion and overexpression of mucosal transforming growth factor (TGF) alpha. Both a cholecystokinin (CCK)(2)-receptor antagonist and an epidermal growth factor (EGF)-receptor tyrosine kinase inhibitor significantly reduced the increase in stomach weight. It appears that lack or downregulation of histamine H(2)-receptors might be involved in the pathogenesis of Menetrier's disease.

Lansoprazole induces mucosal protection through gastrin receptor-dependent up-regulation of cyclooxygenase-2 in rats

Proton pump inhibitors (PPIs) are antiulcer agents that have both gastric antisecretory and mucosal protective actions. The mechanisms of PPI-induced gastric mucosal protection are not known. The present study was designed to examine the mechanism for lansoprazole-induced gastric mucosal protection in rats. Rats were given 0.5, 5, and 50 mg/kg/day lansoprazole alone or both lansoprazole (50 mg/kg/day) and a specific gastrin receptor antagonist 3R-1-(2,2-diethoxyethyl)-((4-methylphenyl)amino-carbonyl methyl)-3-((4-methylphenyl)ureidoindoline-2- one) (AG-041R) (3, 10, and 30 mg/kg/day) for 14 days. Serum gastrin concentrations were measured. The expression of cyclooxygenases (COX-1 and COX-2) in the gastric mucosa was analyzed using Western blotting and immunohistochemical staining. Another series of rats was used to examine the 1) levels of prostaglandin (PG) E2 in gastric mucosa, 2) influences of the drugs on gastric damage caused by absolute ethanol, and 3) effects of a COX-2-specific inhibitor on PGE2 in the gastric mucosa and the mucosal protection afforded by lansoprazole. Lansoprazole dose dependently increased the serum gastrin concentration and enhanced the mucosal expression of COX-2 but not that of COX-1. Lansoprazole increased gastric mucosal PGE2 and reduced gastric damage caused by ethanol. Concomitant administration of AG-041R abolished the lansoprazole-induced COX-2 expression, and increased mucosal PGE2 and mucosal protection. A specific COX-2 inhibitor blocked the lansoprazole-induced increase in mucosal PGE2 and mucosal protection. Activation of gastrin receptors by endogenous gastrin has a pivotal role in the effects of lansoprazole on COX-2 up-regulation and mucosal protection in the rat stomach.

Gastritis and hypergastrinemia due to Acinetobacter lwoffii in mice

In mouse models and humans, Helicobacter pylori is associated with an increase in serum gastrin and gastrin-expressing (G) cells with a concomitant decrease in somatostatin-expressing D cells. Inflammation of the gastric mucosa can progress to metaplastic changes in the stomach and to decreased colonization by H. pylori and increased colonization by non-H. pylori organisms. In addition, about 20% of individuals with chronic gastritis are H. pylori negative, suggesting that other organisms may induce gastritis. Consistent with this hypothesis, we report here that Acinetobacter lwoffii causes the same histologic changes as does H. pylori. Gastric epithelial cells were isolated from the entire stomach by an enzymatic method for quantitation by both flow cytometry and morphometric analysis. Two months after mice were inoculated with H. pylori or A. lwoffii, the mucosal T- and B-cell numbers significantly increased. After 4 months of infection, there was a threefold increase in the number of G cells and a doubling in the number of parietal cells. A threefold decrease in the number of D cells occurred in H. pylori- and A. lwoffii-infected mice. Plasma gastrin levels increased after both H. pylori and A. lwoffii infection. Histology revealed the presence of inflammation in the gastric mucosa with both A. lwoffii and H. pylori infection. A periodic acid-Schiff stain-alcian blue stain revealed mucous gland metaplasia of the corpus. Collectively, the results demonstrate that gastritis and hypergastrinemia are not specific for H. pylori but can be induced by other gram-negative bacteria capable of infecting the mouse stomach.

Gastritis and hypergastrinemia due to Acinetobacter lwoffii in mice

In mouse models and humans, Helicobacter pylori is associated with an increase in serum gastrin and gastrin-expressing (G) cells with a concomitant decrease in somatostatin-expressing D cells. Inflammation of the gastric mucosa can progress to metaplastic changes in the stomach and to decreased colonization by H. pylori and increased colonization by non-H. pylori organisms. In addition, about 20% of individuals with chronic gastritis are H. pylori negative, suggesting that other organisms may induce gastritis. Consistent with this hypothesis, we report here that Acinetobacter lwoffii causes the same histologic changes as does H. pylori. Gastric epithelial cells were isolated from the entire stomach by an enzymatic method for quantitation by both flow cytometry and morphometric analysis. Two months after mice were inoculated with H. pylori or A. lwoffii, the mucosal T- and B-cell numbers significantly increased. After 4 months of infection, there was a threefold increase in the number of G cells and a doubling in the number of parietal cells. A threefold decrease in the number of D cells occurred in H. pylori- and A. lwoffii-infected mice. Plasma gastrin levels increased after both H. pylori and A. lwoffii infection. Histology revealed the presence of inflammation in the gastric mucosa with both A. lwoffii and H. pylori infection. A periodic acid-Schiff stain-alcian blue stain revealed mucous gland metaplasia of the corpus. Collectively, the results demonstrate that gastritis and hypergastrinemia are not specific for H. pylori but can be induced by other gram-negative bacteria capable of infecting the mouse stomach.