Article

Zavros Y, Rieder G, Ferguson A, Samuelson LC, Merchant JL.. Genetic or chemical hypochlorhydria is associated with inflammation that modulates parietal and G-cell populations in mice. Gastroenterology 122: 119-133

January 2002
Gastroenterology 122(1):119-33

January 2002
122(1):119-33

DOI:10.1053/gast.2002.30298

Source
PubMed

Authors:

Gabriele Rieder

University of Salzburg

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Reduced gastric acid predisposes the stomach to colonization by bacteria and inflammation. Therefore, we investigated how the chronic gastritis in mice made hypochlorhydric by either gastrin deficiency or omeprazole treatment modulates epithelial cell function. The gastric pathology of 16-week-old wild-type gastrin-expressing (G+/+) and gastrin-deficient (G-/-) mice maintained in conventional housing was compared. G-/- mice were then treated with antibiotics for 20 days. In a separate experiment, G+/+ mice were treated with omeprazole for 2 months or treated with omeprazole and antibiotics. Compared with the G+/+ animals, the hypochlorhydric G-/- mice showed significant inflammation that resolved after 20 days of antibiotic treatment and correlated with a decrease in bacterial overgrowth. Elevated G- and parietal-cell numbers in the G-/- mice, quantified by flow cytometry, normalized after antibiotic treatment. G+/+ mice treated with omeprazole had increased bacteria and mucosal lymphocytes that resolved after antibiotic therapy. Quantitation of the gastric cells in these omeprazole-treated mice revealed a significant increase in G- and parietal-cell numbers. On resolution of the gastritis, a decrease in parietal and gastrin-expressing (G) cells was observed despite sustained hypochlorhydria in the presence of omeprazole. Genetic or chemical hypochlorhydria predisposes the stomach to bacterial overgrowth resulting in inflammation. The specific changes in parietal and G cells correlate with the presence of inflammation and not directly with gastric acid. Thus, the normal stomach responds to inflammation by increasing the number and function of cell types that are able to maximize gastric acid output.

Role of Bacterial Overgrowth in the Stomach as an Additional Risk Factor for Gastritis

Article

Full-text available

Jan 2003
CAN J GASTROENTEROL

Gastric bacteria can either be ingested or ascend from the distal bowel; however, their survival is usually limited by gastric acidity and motility. A reduction in gastric acid can result in bacterial overgrowth in the stomach and proximal small bowel, and the number of organisms rises as the intragastric pH rises. The increased risk of noncardia gastric cancer seen in patients with hypochlorhydria may be explained by an excess of nitrites and N-nitroso compounds (NOCs). These compounds are found in the diet of populations with a high gastric cancer risk, but can also be produced by the organisms that exist in the hypochlorhydria stomach. It has long been hypothsized that nitrites and NOCs act as one of the triggers in the atrophy-metaplasia-dysplasia-carcinoma path. However, although indirect data have linked the premalignant changes of metaplasia and dysplasia to NOCs, direct measurement of gastric nitrites and NOCs has not confirmed such a link. The role of Helicobacter pylori in bacterial overgrowth is mainly as a cause of hypochlorhydria resulting from atrophic gastritis, leading to a reduction in the parietal cell mass. Acid-suppressing drugs can result in bacterial overgrowth and increased nitrites and NOCs, although there is no current evidence for an increased risk of gastric cancer in patients taking them. One explanation is that the stomach appears to be colonized by different organisms than those in patients with hypochlorhydria for other reasons. There is some evidence that bacterial overgrowth per se can cause gastric inflammation in mice; however, although in humans the degree of gastric inflammation is greater when overgrowth is more prominant this may simply reflect the greater degree of hypochlorhydria in patients with a more severe H pylori-induced inflammation.

Mouse models for gastric cancer: Matching models to biological questions

Article

Full-text available

Jan 2016
J GASTROEN HEPATOL

Gastric cancer is the third leading cause of cancer-related mortality worldwide. This is in part due to the asymptomatic nature of the disease, which often results in late-stage diagnosis, at which point there are limited treatment options. Even when treated successfully, gastric cancer patients have a high risk of tumor recurrence and acquired drug resistance. It is vital to gain a better understanding of the molecular mechanisms underlying gastric cancer pathogenesis to facilitate the design of new-targeted therapies that may improve patient survival. A number of chemically and genetically engineered mouse models of gastric cancer have provided significant insight into the contribution of genetic and environmental factors to disease onset and progression. This review outlines the strengths and limitations of current mouse models of gastric cancer and their relevance to the pre-clinical development of new therapeutics. This article is protected by copyright. All rights reserved.

909 Malignantly Transformed Bone Marrow-Derived Mesenchymal Stem Cells Promote CD44 Positive Epithelial Cell Proliferation and the Development of Gastrointestinal Stromal-Type Tumors

Article

May 2012
GASTROENTEROLOGY

Mesenchymal Stem Cells Induce Epithelial Proliferation Within the Inflamed Stomach.

Article

Full-text available

May 2014
AM J PHYSIOL-GASTR L

Bone marrow-derived mesenchymal stem cells (MSCs) sustain cancer cells by creating a microenvironment favorable for tumor growth. In particular, MSCs have been implicated in gastric cancer development. There is extensive evidence suggesting that Hedgehog signaling regulates tumor growth. However, very little is known regarding the precise roles of Hedgehog signaling and MSCs in tumor development within the stomach. The current study tests that hypothesis that Shh, secreted from MSCs, provides a proliferative stimulus for the gastric epithelium in the presence of inflammation. RFP-expressing MSCs transformed in vitro (stMSCs) were transduced with lentiviral constructs containing a vector control (stMSC(vect)) or shRNA targeting the Shh gene (stMSC(ShhKO)). Gastric submucosal transplantation of wild type MSCs (wtMSCs), wild type MSCs over-expressing Shh (wtMSC(Shh)), stMSC(vect) or stMSC(ShhKO) cells in C57BL/6 control (BL/6) or gastrin-deficient (GKO) mice was performed and mice analyzed 30 and 60 days post-transplantation. Compared to BL/6 mice transplanted with wtMSC(Shh) and stMSC(vect) cells, inflamed GKO mice developed aggressive gastric tumors. Tumor development was not observed in mouse stomachs transplanted with wtMSC or stMSC(ShhKO) cells. Compared to stMSC(ShhKO) transplanted mice, within the inflamed GKO mouse stomach Shh-expressing stMSCs(vect) and wtMSCs(Shh) induced proliferation of CD44-positive cells. CD44-positive cells clustered in gland-like structures within the tumor stroma and were positive for Ptch expression. We conclude that Shh, secreted from MSCs, provides a proliferative stimulus for the gastric epithelium that is associated with tumor development, a response that is sustained by chronic inflammation.

Gastritis Promotes an Activated Bone Marrow-Derived Mesenchymal Stem Cell with a Phenotype Reminiscent of a Cancer-Promoting Cell

Article

Full-text available

Nov 2013
DIGEST DIS SCI

Bone marrow-derived mesenchymal stem cells (BM-MSCs) promote gastric cancer in response to gastritis. In culture, BM-MSCs are prone to mutation with continued passage but it is unknown whether a similar process occurs in vivo in response to gastritis. The purpose of this study was to identify the role of chronic gastritis in the transformation of BM-MSCs leading to an activated cancer-promoting phenotype. Age matched C57BL/6 (BL/6) and gastrin deficient (GKO) mice were used for isolation of stomach, serum and mesenchymal stem cells (MSCs) at 3 and 6 months of age. MSC activation was assessed by growth curve analysis, fluorescence-activated cell sorting and xenograft assays. To allow for the isolation of bone marrow-derived stromal cells and assay in response to chronic gastritis, IRG/Vav-1(Cre) mice that expressed both enhanced green fluorescent protein-expressing hematopoietic cells and red fluorescent protein-expressing stromal cells were generated. In a parabiosis experiment, IRG/Vav-1(Cre) mice were paired to either an uninfected Vav-1(Cre) littermate or a BL/6 mouse inoculated with Helicobacter pylori. GKO mice displayed severe atrophic gastritis accompanied by elevated gastric tissue and circulating transforming growth factor beta (TGFβ) by 3 months of age. Compared to BM-MSCs isolated from uninflamed BL/6 mice, BM-MSCs isolated from GKO mice displayed an increased proliferative rate and elevated phosphorylated-Smad3 suggesting active TGFβ signaling. In xenograft assays, mice injected with BM-MSCs from 6-month-old GKO animals displayed tumor growth. RFP+ stromal cells were rapidly recruited to the gastric mucosa of H. pylori parabionts and exhibited changes in gene expression. Gastritis promotes the in vivo activation of BM-MSCs to a phenotype reminiscent of a cancer-promoting cell.

Prevalence and Associated Risk Factors of Helicobacter pylori Negative Gastritis

Article

Full-text available

Feb 2016

Abstract Background: Helicobacter pylori (Hp) infection has previously been thought to account for nearly all chronic gastritis. However, recent studies have suggested that Hp-negative gastritis is common and increasing in prevalence in the United States. The etiology and associated risk factors for Hp-negative gastritis remain uncertain. Objective: Our primary aims were to: 1) Assess the prevalence of Hp-negative gastritis and 2) Characterize differences and similarities in associated demographics, clinical features, risk factors and medical co-morbidities between Hp-negative and Hp-positive gastritis. Methods: We performed a retrospective study of 131 consecutive patients who were referred for EGD for upper gastrointestinal symptoms at a single tertiary care center from 7/2012-7/2013. Referral symptoms comprised dysphagia, abdominal pain, nausea, vomiting, iron deficiency anemia, bloating, belching, or Barrett’s esophagus surveillance. All 131 cases had biopsies at this institution, and clinical, demographic, and laboratory data were compared between individuals with Hp-negative and Hp-positive gastritis. Results: Among all patients surveyed, 50 (38.2%) had gastritis present on biopsy, of which 39 (78.0%) were Hp- negative and 11 (22.0%) were Hp-positive. Among Hp-negative gastritis patients, 61.5% had chronic chemical gastritis, while 33.2% had chronic inactive gastritis and 5.1% had chronic active gastritis. Among Hp-positive patients, 100% had chronic active gastritis. The distribution of Hp-negative vs. Hp-positive gastritis differed (p = 0.016): antrum only (76.9% vs. 36.0%), corpus (10.3% vs. 36.0%), antrum and corpus (12.8% vs. 27.0%). Racial distribution differed significantly between Hp-negative (61.5% Caucasian, 20.5% African American, 18.0% other races) and Hp-positive (0% Caucasian, 72.7% African-American, and 27.3% other races) patients (p < 0.001). The presence of medical co-morbidities was significantly associated with Hp-negative gastritis vs. Hp-positive gastritis: 82.1% vs. 18.2% (p < 0.001). GERD was the most common medical co-morbidity noted, being present in 66.7% of Hp-negative patients in contrast to only 9.1% of Hp-positive gastritis (p = 0.001). There were no significant differences between Hp-negative and Hp-positive patients in predominant symptoms, primary referral indication, age, gender, prior Hp infection, tobacco, alcohol, PPI, NSAID, or antibiotic usage. Conclusions: Hp-negative gastritis is a common entity that comprised the majority of consecutive gastritis cases in our study. It was significantly associated with the presence of medical co-morbidities, particularly GERD, and Caucasian race. Hp-negative gastritis also appears to have an anatomic predilection for the antrum. No association with referral symptoms, PPI use, NSAID use, or other risk factors was identified. Large-scale prospective studies are needed to further delineate the natural history, etiology, risk factors, pathogenesis, and clinical relevance of this increasingly common disease entity.

Efecto de cisapride sobre el sobrecrecimiento bacteriano intestinal y la translocación bacteriana en la cirrosis

Article

Oct 2004

Alberto Pardo Balteiro

Inflammation and Gli2 Suppress Gastrin Gene Expression in a Murine Model of Antral Hyperplasia

Article

Full-text available

Oct 2012
PLOS ONE

Chronic inflammation in the stomach can lead to gastric cancer. We previously reported that gastrin-deficient (Gast(-/-)) mice develop bacterial overgrowth, inflammatory infiltrate, increased Il-1β expression, antral hyperplasia and eventually antral tumors. Since Hedgehog (Hh) signaling is active in gastric cancers but its role in precursor lesions is poorly understood, we examined the role of inflammation and Hh signaling in antral hyperplasia. LacZ reporter mice for Sonic hedgehog (Shh), Gli1, and Gli2 expression bred onto the Gast(-/-) background revealed reduced Shh and Gli1 expression in the antra compared to wild type controls (WT). Gli2 expression in the Gast(-/-) corpus was unchanged. However in the hyperplastic Gast(-/-) antra, Gli2 expression increased in both the mesenchyme and epithelium, whereas expression in WT mice remained exclusively mesenchymal. These observations suggested that Gli2 is differentially regulated in the hyperplastic Gast(-/-) antrum versus the corpus and by a Shh ligand-independent mechanism. Moreover, the proinflammatory cytokines Il-1β and Il-11, which promote gastric epithelial proliferation, were increased in the Gast(-/-) stomach along with Infγ. To test if inflammation could account for elevated epithelial Gli2 expression in the Gast(-/-) antra, the human gastric cell line AGS was treated with IL-1β and was found to increase GLI2 but decrease GLI1 levels. IL-1β also repressed human GAST gene expression. Indeed, GLI2 but not GLI1 or GLI3 expression repressed gastrin luciferase reporter activity by ∼50 percent. Moreover, chromatin immunoprecipitation of GLI2 in AGS cells confirmed that GLI2 directly binds to the GAST promoter. Using a mouse model of constitutively active epithelial GLI2 expression, we found that activated GLI2 repressed Gast expression but induced Il-1β gene expression and proliferation in the gastric antrum, along with a reduction of the number of G-cells. In summary, epithelial Gli2 expression was sufficient to stimulate Il-1β expression, repress Gast gene expression and increase proliferation, leading to antral hyperplasia.

Histamine Signaling Is Essential for Tissue Macrophage Differentiation and Suppression of Bacterial Overgrowth in the Stomach

Article

Full-text available

Sep 2022

Background & Aims Histamine in the stomach is traditionally considered to regulate acid secretion but has also been reported to participate in macrophage differentiation, which plays an important role in tissue homeostasis. Therefore, this study aimed to uncover the precise role of histamine in mediating macrophage differentiation and in maintaining stomach homeostasis. Methods Here, we expand on this role using histidine decarboxylase knockout (Hdc-/-) mice with hypertrophic gastropathy. In-depth in vivo studies were performed in Hdc-/- mice, germ-free Hdc-/- mice and bone-marrow transplanted Hdc-/- mice. The stomach macrophage populations and function were characterized by flow cytometry. To identify stomach macrophages and find the new macrophage population, we performed single-cell RNA seq analysis on Hdc+/+ and Hdc-/- stomach tissues. Results Single-cell RNA-sequencing and flow cytometry of the stomach cells of Hdc-/- mice revealed alterations in the ratios of three distinct tissue macrophage populations (F4/80⁺Il1bhigh, F4/80⁺CD93⁺, and F4/80⁻MHCIIhighCD74high). Tissue macrophages of the stomach of Hdc-/- mice showed impaired phagocytic activity, increasing the bacterial burden of the stomach and attenuating hypertrophic gastropathy in germ-free Hdc-/- mice. The transplantation of bone marrow cells of Hdc+/+ mice to Hdc-/- mice recovered the normal differentiation of stomach macrophages and relieved the hypertrophic gastropathy of Hdc-/- mice. Conclusions This study demonstrated the importance of histamine signaling in tissue macrophage differentiation and maintenance of gastric homeostasis through the suppression of bacterial overgrowth in the stomach.

Roles of G Protein-Coupled Receptors (GPCRs) in Gastrointestinal Cancers: Focus on Sphingosine 1-Shosphate Receptors, Angiotensin II Receptors, and Estrogen-Related GPCRs

Article

Full-text available

Nov 2021

It is well established that gastrointestinal (GI) cancers are common and devastating diseases around the world. Despite the significant progress that has been made in the treatment of GI cancers, the mortality rates remain high, indicating a real need to explore the complex pathogenesis and develop more effective therapeutics for GI cancers. G protein-coupled receptors (GPCRs) are critical signaling molecules involved in various biological processes including cell growth, proliferation, and death, as well as immune responses and inflammation regulation. Substantial evidence has demonstrated crucial roles of GPCRs in the development of GI cancers, which provided an impetus for further research regarding the pathophysiological mechanisms and drug discovery of GI cancers. In this review, we mainly discuss the roles of sphingosine 1-phosphate receptors (S1PRs), angiotensin II receptors, estrogen-related GPCRs, and some other important GPCRs in the development of colorectal, gastric, and esophageal cancer, and explore the potential of GPCRs as therapeutic targets.

Ulcer Disease in the Excluded Segments after Roux-en-Y Gastric Bypass: a Current Review of the Literature

Article

Full-text available

Mar 2021
OBES SURG

Ulcer disease in excluded segments after Roux-Y gastric bypass (RYGB) is rare but can evolve into a life-threatening situation. The excluded segments exhibit a different behavior from that of non-altered anatomy; perforated ulcers do not result in pneumoperitoneum or free fluid, and therefore must be met with a low threshold for surgical exploration. The anatomical changes after RYGB impede routine access to the remnant stomach and duodenum. There are various options to address bleeding or perforated ulcers. While oversewing and drainage preserves the anatomy and forgoes resection, remnant gastrectomy offers a definitive solution. The importance of traditional risk factors such as smoking or use of non-steroidal anti-inflammatory drugs is unclear. Eradication of Helicobacter pylori and secondary prophylaxis with proton-pump inhibitors is advisable, albeit in double-dose.

Colonization by Pseudomonas aeruginosa and Staphylococcus aureus of Antral Biopsy Specimens from Gastritis Patients Uninfected with Helicobacter Pylori

Article

Full-text available

May 2020

Purpose: Roles and incidence of some microorganisms that transiently or permanently colonize the human stomach are still unknown despite advances in gastroenterology. We aimed to examine the incidence of four microorganisms, Helicobacter pylori, Pseudomonas aeruginosa, Staphylococcus aureus, and Staphylococcus epidermidis, in the antral biopsy specimens of patients with gastroduodenal conditions. Patients and methods: Patients (67 females, 33 males; mean age = 49.5 years) were initially examined and diagnosed by a gastroenterologist at the Mehrad Hospital, Tehran, Iran. We enrolled those who underwent the upper gastrointestinal endoscopy because of gastroduodenal conditions. Two antral biopsy samples were taken by endoscopy; the first sample was used for the "rapid urease test" to confirm H. pylori. The second was used for DNA extraction and PCR analyses with specific, corresponding primer sets to establish the presence of the four microorganisms. Our study was approved by the Ethics Committee at the Tarbiat Modares University, Tehran. Results: Based on pathology and endoscopy findings, we divided the patients into three groups: 62 presented with gastritis, 18 with duodenal ulcer, and 20 gastric ulcer. The number of patients with P. aeruginosa but without H. pylori significantly differed from the number of those co-infected with both microorganisms (P = 0.03). Additionally, a similar significance was found between the incidence of S. aureus in patients without H. pylori and those with both infections (P = 0.04). Our results indicated that a significant number of patients with gastritis were colonized with P. aeruginosa or S. aureus without being co-infected with H. pylori (P < 0.001). Interestingly, the incidence of colonization by P. aeruginosa of patients without H. pylori (45/49, 91.8%) was higher than that by S. aureus (28/49, 57%). Conclusion: The number of patients without H. pylori but with P. aeruginosa or with S. aureus infection significantly differed from that with both infections, respectively. Our study thus shows that patients without H. pylori infection are prone to be colonized by P. aeruginosa or S. aureus, indicating that targeted antibiotic regimens are necessary for clinically treating them.

Hormonal Suppression of Stem Cells Inhibits Symmetric Cell Division and Gastric Tumorigenesis

Article

Feb 2020

Cancer is believed to arise from stem cells, but mechanisms that limit the acquisition of mutations and tumor development have not been well defined. We show that a +4 stem cell (SC) in the gastric antrum, marked by expression of Cck2r (a GPCR) and Delta-like ligand 1 (DLL1), is a label-retaining cell that undergoes predominant asymmetric cell division. This +4 antral SC is Notch1low/ Numb+ and repressed by signaling from gastrin-expressing endocrine (G) cells. Chemical carcinogenesis of the stomach is associated with loss of G cells, increased symmetric stem cell division, glandular fission, and more rapid stem cell lineage tracing, a process that can be suppressed by exogenous gastrin treatment. This hormonal suppression is associated with a marked reduction in gastric cancer mutational load, as revealed by exomic sequencing. Taken together, our results show that gastric tumorigenesis is associated with increased symmetric cell division that facilitates mutation and is suppressed by GPCR signaling.

On bryophyte flora of the Drevlyansky nature reserve [In Ukrainian]

Article

Full-text available

Oct 2016

Accoding to previous data, in the bryoflora of the Drevlyansky nature reserve (the Zhytomyr Region, Ukraine) it was established 85 species, out of them 72 ones are reported for the first time. This reserve plays the important role in protection of epilithic bryophytes of the Ukrainian Polissya. Fissidens fontanus, a species from the Red Data Book of Ukraine, as well as regional rare bryophytes (Riccardia incurvata, Riccia rhenana, Syntrichia papillosa, Schistidium submuticum and others) occur there.

Recapitulating Human Gastric Cancer Pathogenesis: Experimental Models of Gastric Cancer

Chapter

Aug 2016
ADV EXP MED BIOL

This review focuses on the various experimental models to study gastric cancer pathogenesis, with the role of genetically engineered mouse models (GEMMs) used as the major examples. We review differences in human stomach anatomy compared to the stomachs of the experimental models, including the mouse and invertebrate models such as Drosophila and C. elegans. The contribution of major signaling pathways, e.g., Notch, Hedgehog, AKT/PI3K is discussed in the context of their potential contribution to foregut tumorigenesis. We critically examine the rationale behind specific GEMMs, chemical carcinogens, dietary promoters, Helicobacter infection, and direct mutagenesis of relevant oncogenes and tumor suppressor that have been developed to study gastric cancer pathogenesis. Despite species differences, more efficient and effective models to test specific genes and pathways disrupted in human gastric carcinogenesis have yet to emerge. As we better understand these species differences, “humanized” versions of mouse models will more closely approximate human gastric cancer pathogenesis. Towards that end, epigenetic marks on chromatin, the gut microbiota, and ways of manipulating the immune system will likely move center stage, permitting greater overlap between rodent and human cancer phenotypes thus providing a unified progression model.

Characterization of the Role of Host and Dietary Factors in the Establishment of Bacteria in the Gastrointestinal Tract

Article

Aug 2016

Janina Krumbeck

Probiotic bacteria and synbiotics are used as therapeutic and prophylactic agents. The majority of probiotic and synbiotic applications contain bacterial strains that are allochthonous to the human gastrointestinal (GI) tract. Accordingly, many bacterial strains do not survive digestion, or are not capable of persisting and competing the resident gut microbiota, and are therefore washed out of the GI tract shortly after the treatment is discontinued. This might reduce the health effects of these treatments. Therefore, research is needed to address the ecological challenges that probiotic strains encounter in the GI tract in order to develop probiotic regimens. Determining which ecological factors are limiting the colonization of bacteria remains a challenge. To gain insight into the complex interplay between host and microbe, we chose Lactobacillus reuteri and its rodent host as a model to investigate which genes of L. reuteri contribute to tolerance towards host gastric acid secretion. We established the urease cluster as the predominant factor in mediating resistance to gastric acid, and a mutation of this cluster resulted in substantially decreased population levels of L. reuteri in mice. Secondly, we established a method to select for synergistic synbiotic combinations. Based on in vivo selection (IVS), autochthonous putative probiotic strains are enriched in the GI tract of subjects by the continued consumption of a prebiotic. We used IVS to select a strain of Bifidobacterium adolescentis that became enriched in a human feeding trail with galactooligosaccharides (GOS). Here we have shown that the synbiotic combination of Bifidobacterium adolescentis IVS-1 and GOS significantly enriched for the putative probiotic component in rats. IVS-1 became the most dominant operational taxonomic unit in the GI tract, outcompeting the resident Bifidobacterium species. Similarly, we tested this synbiotic in a human trial with obese adults. In this random, placebo-controlled parallel arm study, the synbiotic combination of IVS-1 and GOS led to establishment of IVS-1 in significantly higher numbers in the GI tract than a commercial synbiotic. Together, the studies presented in this dissertation allowed new insights into the colonization factors of a true GI symbiont, which could contribute to the development of improved probiotics, and provided novel insight into a rational selection of probiotics and synbiotics. Advisors: Robert W. Hutkins and Jens Walter

Characterization of the ecological role of genes mediating acid resistance in Lactobacillus reuteri during colonization of the gastrointestinal tract

Article

Nov 2015
ENVIRON MICROBIOL

Rodent-derived strains of Lactobacillus reuteri densely colonize the forestomach of mice and possess several genes whose predicted functions constitute adaptations towards an acidic environment. The objective of this study was to systematically determine which genes of L. reuteri 100-23 contribute to tolerance towards host gastric acid secretion. Genes predicted to be involved in acid resistance were inactivated, and their contribution to survival under acidic conditions was confirmed in model gastric juice. Fitness of five mutants that showed impaired in vitro acid resistance were then compared through competition experiments in ex-germ-free mice that were either treated with omeprazole, a proton-pump inhibitor that suppresses acid secretion in the stomach, or left untreated. This analysis revealed that the urease cluster was the predominant factor in mediating resistance to gastric acid production. Population levels of the mutant, which were substantially decreased in untreated mice, were almost completely restored through omeprazole, demonstrating that urease production in L. reuteri is mainly devoted to overcome gastric acid. The findings provide novel information on the mechanisms by which L. reuteri colonizes its gastric niche and demonstrate that in silico gene predictions and in vitro tests have limitations for predicting the ecological functions of colonization factors in bacterial symbionts.

To be or not to be: The host genetic factor and beyond in Helicobacter pylori mediated gastro-duodenal diseases

Article

Full-text available

Mar 2015
WORLD J GASTROENTERO

Helicobacter pylori (H. pylori) have long been associated with a spectrum of disease outcomes in the gastro-duodenal system. Heterogeneity in bacterial virulence factors or strains is not enough to explain the divergent disease phenotypes manifested by the infection. This review focuses on host genetic factors that are involved during infection and eventually are thought to influence the disease phenotype. We have summarized the different host genes that have been investigated for association studies in H. pylori mediated duodenal ulcer or gastric cancer. We discuss that as the bacteria co-evolved with the host; these host gene also show much variation across different ethnic population. We illustrate the allelic distribution of interleukin-1B, across different population which is one of the most popular candidate gene studied with respect to H. pylori infections. Further, we highlight that several polymorphisms in the pathway gene can by itself or collectively affect the acid secretion pathway axis (gastrin: somatostatin) thereby resulting in a spectrum of disease phenotype.

UEGW nutrition poster

Data

Full-text available

Jan 2015

Serhii Vakal

Mouse Models of Gastric Carcinogenesis

Article

Full-text available

Jun 2014

Gastric cancer is one of the most common cancers in the world. Animal models have been used to elucidate the details of the molecular mechanisms of various cancers. However, most inbred strains of mice have resistance to gastric carcinogenesis. Helicobacter infection and carcinogen treatment have been used to establish mouse models that exhibit phenotypes similar to those of human gastric cancer. A large number of transgenic and knockout mouse models of gastric cancer have been developed using genetic engineering. A combination of carcinogens and gene manipulation has been applied to facilitate development of advanced gastric cancer; however, it is rare for mouse models of gastric cancer to show aggressive, metastatic phenotypes required for preclinical studies. Here, we review current mouse models of gastric carcinogenesis and provide our perspectives on future developments in this field.

Helminth co-infection in Helicobacter pylori infected INS-GAS mice attenuates gastric premalignant lesions of epithelial dysplasia and glandular atrophy and preserves colonization resistance of the stomach to lower bowel microbiota

Article

Apr 2014

Higher prevalence of helminth infections in H. pylori infected children was suggested to potentially lower the life-time risk for gastric adenocarcinoma. In rodent models, helminth co-infection does not reduce Helicobacter-induced inflammation but delays progression of pre-malignant gastric lesions. Because gastric cancer in INS-GAS mice is promoted by intestinal microflora, the impact of Heligmosomoides polygyrus co-infection on H. pylori-associated gastric lesions and microflora were evaluated. Male INS-GAS mice co-infected with H. pylori and H. polygyrus for 5 months were assessed for gastrointestinal lesions, inflammation-related mRNA expression, FoxP3+ cells, epithelial proliferation, and gastric colonization with H. pylori and Altered Schaedler Flora. Despite similar gastric inflammation and high levels of proinflammatory mRNA, helminth co-infection increased FoxP3+ cells in the corpus and reduced H. pylori-associated gastric atrophy (p<0.04), dysplasia (p<0.02) and prevented H. pylori-induced changes in the gastric flora (p<0.05). This is the first evidence of helminth infection reducing H. pylori-induced gastric lesions while inhibiting changes in gastric flora, consistent with prior observations that gastric colonization with enteric microbiota accelerated gastric lesions in INS-GAS mice. Identifying how helminths reduce gastric premalignant lesions and impact bacterial colonization of the H. pylori infected stomach could lead to new treatment strategies to inhibit progression from chronic gastritis to cancer in humans.

Mouse Models of Gastric Cancer

Article

Full-text available

Mar 2013

Animal models have greatly enriched our understanding of the molecular mechanisms of numerous types of cancers. Gastric cancer is one of the most common cancers worldwide, with a poor prognosis and high incidence of drug-resistance. However, most inbred strains of mice have proven resistant to gastric carcinogenesis. To establish useful models which mimic human gastric cancer phenotypes, investigators have utilized animals infected with Helicobacter species and treated with carcinogens. In addition, by exploiting genetic engineering, a variety of transgenic and knockout mouse models of gastric cancer have emerged, such as INS-GAS mice and TFF1 knockout mice. Investigators have used the combination of carcinogens and gene alteration to accelerate gastric cancer development, but rarely do mouse models show an aggressive and metastatic gastric cancer phenotype that could be relevant to preclinical studies, which may require more specific targeting of gastric progenitor cells. Here, we review current gastric carcinogenesis mouse models and provide our future perspectives on this field.

Enterococcus faecalis Infection Causes Inflammation, Intracellular Oxphos-Independent ROS Production, and DNA Damage in Human Gastric Cancer Cells

Article

Full-text available

Apr 2013
PLOS ONE

Background: Achlorhydria caused by e.g. atrophic gastritis allows for bacterial overgrowth, which induces chronic inflammation and damage to the mucosal cells of infected individuals driving gastric malignancies and cancer. Enterococcus faecalis (E. faecalis) can colonize achlohydric stomachs and we therefore wanted to study the impact of E. faecalis infection on inflammatory response, reactive oxygen species (ROS) formation, mitochondrial respiration, and mitochondrial genetic stability in gastric mucosal cells. Methods: To separate the changes induced by bacteria from those of the inflammatory cells we established an in vitro E. faecalis infection model system using the gastric carcinoma cell line MKN74. Total ROS and superoxide was measured by fluorescence microscopy. Cellular oxygen consumption was characterized non-invasively using XF24 microplate based respirometry. Gene expression was examined by microarray, and response pathways were identified by Gene Set Analysis (GSA). Selected gene transcripts were verified by quantitative real-time polymerase chain reaction (qRT-PCR). Mitochondrial mutations were determined by sequencing. Results: Infection of MKN74 cells with E. faecalis induced intracellular ROS production through a pathway independent of oxidative phosphorylation (oxphos). Furthermore, E. faecalis infection induced mitochondrial DNA instability. Following infection, genes coding for inflammatory response proteins were transcriptionally up-regulated while DNA damage repair and cell cycle control genes were down-regulated. Cell growth slowed down when infected with viable E. faecalis and responded in a dose dependent manner to E. faecalis lysate. Conclusions: Infection by E. faecalis induced an oxphos-independent intracellular ROS response and damaged the mitochondrial genome in gastric cell culture. Finally the bacteria induced an NF-κB inflammatory response as well as impaired DNA damage response and cell cycle control gene expression. Transcript profiling: Array Express accession number E-MEXP-3496.

Sonic Hedgehog contributes to gastric mucosal restitution after injury

Article

Full-text available

Oct 2012
LAB INVEST

Eradication of Helicobacter pylori correlates with regeneration of the gastric epithelium, ulcer healing and re-expression of the gastric morphogen Sonic Hedgehog (Shh). We sought to identify the role of Shh as a regulator of gastric epithelial regeneration during wound healing. A mouse model expressing a parietal cell-specific, tamoxifen-inducible deletion of Shh (HKCre(ERT2);Shh(flox/flox) or PC-iShhKO) was developed. Stomachs were collected and compared 7-150 days after the final vehicle or tamoxifen injection. Ulcers were induced in both controls and PC-iShhKO mice using acetic acid and ulcer size compared 1 and 7 days post induction. (1) Re-expression of Shh correlates with decreased hyperproliferation: Compared to controls, PC-iShhKO mice developed foveolar hyperplasia. Restoration of normal gastric epithelial architecture and differentiation correlated with the re-expression of Shh in PC-iShhKO mice 150 days after the final tamoxifen injection. At the tamoxifen dose used to induce Cre recombination there was no genotoxicity reported in either HKCre(ERT2) or Shh(flox/flox) control mouse stomachs. (2) Delayed wound healing in PC-iShhKO mouse stomachs: To identify the role of Shh in gastric regeneration, an acetic acid ulcer was induced in control and PC-iShhKO mice. Ulcers began to heal in control mice by 7 days after induction. Ulcer healing was documented by decreased ulcer size, angiogenesis, macrophage infiltration and formation of granulation tissue that correlated with the re-expression of Shh within the ulcerated tissue. PC-iShhKO mice did not show evidence of ulcer healing. Re-expression of Shh contributes to gastric regeneration. Our current study may have clinical implications given that eradication of H. pylori correlates with re-expression of Shh, regeneration of the gastric epithelium and ulcer healing.Laboratory Investigation advance online publication 22 October 2012; doi:10.1038/labinvest.2012.148.

Hepcidin is localised in gastric parietal cells, regulates acid secretion and is induced by Helicobacter pylori infection

Article

Jul 2011
GUT

Hepcidin is an antimicrobial peptide and the central regulator of iron metabolism. Given that hepcidin was shown to be expressed in a variety of extrahepatic tissues and that stomach plays a role in iron absorption and in defence against infections, this study analysed the importance of hepcidin in the stomach. Expression and localisation of gastric hepcidin was studied by quantitative RT-PCR, western blot, immunofluorescence and in situ hybridisation. Regulation of gastric hepcidin expression was analysed both in vitro and in vivo. Hepcidin wild-type (WT) and knockout (KO) animals were used to determine the impact of hepcidin on gastric bacterial overgrowth as well as gastric acid secretion. Hepcidin was abundantly expressed in the gastric fundus and corpus of all tested species. Treatment of AGS cells with ferric nitrilotriacetate solution downregulated hepcidin expression levels, while desferroxamine, interleukin 6 and Helicobacter pylori infection upregulated it. In humans, gastric hepcidin expression was elevated during H pylori infection and normalised after successful eradication. Gastric hepcidin is localised in parietal cells that are indispensable for gastric acid secretion. Comparisons of WT and hepcidin KO mice revealed that acid secretion in hepcidin-deficient mice is markedly reduced and is associated with gastric bacterial overgrowth, expression changes in multiple factors involved in acid secretion (Atp4a, Cck2r,Gas, Sst and Sst2r) and with reduced circulating gastrin levels. In WT mice, pantoprazole activated and histamine downregulated hepcidin expression levels. Hepcidin is a product of parietal cells regulating gastric acid production and may contribute to development of gastric ulcers under stress conditions.

MiR-449 inhibits cell proliferation and is down-regulated in gastric cancer

Article

Full-text available

Mar 2011
MOL CANCER

Gastric cancer is the fourth most common cancer in the world and the second most prevalent cause of cancer related death. The development of gastric cancer is mainly associated with H. Pylori infection leading to a focus in pathology studies on bacterial and environmental factors, and to a lesser extent on the mechanistic development of the tumour. MicroRNAs are small non-coding RNA molecules involved in post-transcriptional gene regulation. They are found to regulate genes involved in diverse biological functions and alterations in microRNA expression have been linked to the pathogenesis of many malignancies. The current study is focused on identifying microRNAs involved in gastric carcinogenesis and to explore their mechanistic relevance by characterizing their targets. Invitrogen NCode miRNA microarrays identified miR-449 to be decreased in 1-year-old Gastrin KO mice and in H. Pylori infected gastric tissues compared to tissues from wild type animals. Growth rate of gastric cell lines over-expressing miR-449 was inhibited by 60% compared to controls. FACS cell cycle analysis of miR-449 over-expressing cells showed a significant increase in the sub-G1 fraction indicative of apoptosis. ß-Gal assays indicated a senescent phenotype of gastric cell lines over-expressing miR-449. Affymetrix 133v2 arrays identified GMNN, MET, CCNE2, SIRT1 and CDK6 as miR-449 targets. Luciferase assays were used to confirm GMNN, MET, CCNE2 and SIRT1 as direct targets. We also show that miR-449 over-expression activated p53 and its downstream target p21 as well as the apoptosis markers cleaved CASP3 and PARP. Importantly, qPCR analyses showed a loss of miR-449 expression in human clinical gastric tumours compared to normal tissues. In this study, we document a diminished expression of miR-449 in Gastrin KO mice and further confirmed its loss in human gastric tumours. We investigated the function of miR-449 by identifying its direct targets. Furthermore we show that miR-449 induces senescence and apoptosis by activating the p53 pathway.

Epithelial BMP signaling is required for proper specification of epithelial cell lineages and gastric endocrine cells

Article

Full-text available

Mar 2011
AM J PHYSIOL-GASTR L

Bone morphogenetic protein (BMP) signaling within the gastrointestinal tract is complex. BMP ligands and their receptors are expressed in both epithelial and mesenchymal compartments, suggesting bidirectional signaling between these two entities. Despite an increasing interest in BMP signaling in gut physiology and pathologies, the distinct contribution of BMP signaling in the epithelium vs. the mesenchyme in gastrointestinal homeostasis remains to be established. We aimed to investigate the role of epithelial BMP signaling in gastric organogenesis, gland morphogenesis, and maintenance of epithelial cell functions. Using the Cre/loxP system, we generated a mouse model with an early deletion during development of BMP receptor 1A (Bmpr1a) exclusively in the foregut endoderm. Bmpr1a(ΔGEC) mice showed no severe abnormalities in gastric organogenesis, gland epithelial proliferation, or morphogenesis, suggesting only a minor role for epithelial BMP signaling in these processes. However, early loss of BMP signaling in foregut endoderm did impact on gastric patterning, leading to an anteriorization of the stomach. In addition, numbers of parietal cells were reduced in Bmpr1a(ΔGEC) mice. Epithelial BMP deletion significantly increased the numbers of chromogranin A-, ghrelin-, somatostatin-, gastrin-, and serotonin-expressing gastric endocrine cells. Cancer never developed in young adult (<100 days) Bmpr1a-inactivated mice although a marker of spasmolytic polypeptide-expressing metaplasia was upregulated. Using this model, we have uncovered that BMP signaling negatively regulates the proliferation and commitment of endocrine precursor cells. Our data also indicate that loss of BMP signaling in epithelial gastric cells alone is not sufficient to induce gastric neoplasia.

Using Human-Induced Pluripotent Stem Cell-Derived Organoids to Identify New Pathologies in Patients With PDX1 Mutations

Article

Jul 2022

Background aims: Two patients with homozygous mutations in PDX1 presented with pancreatic agenesis, chronic diarrhea and poor weight gain, the causes of which were not identified through routine clinical testing. We aim to perform a deep analysis of the stomach and intestine using organoids derived from induced pluripotent stem cells from PDX1188delC/188delC patients. Methods: Gastric fundic, antral and duodenal organoids were generated using iPSC lines from a PDX1188delC/188delC patient and an isogenic iPSC line where the PDX1 point mutation was corrected. Results: Patient-derived PDX1188delC/188delC antral organoids exhibited an intestinal phenotype, while intestinal organoids underwent gastric metaplasia with significant reduction in enteroendocrine cells. This prompted a re-examination of gastric and intestinal biopsies from both PDX1188delC/188delC patients, which recapitulated the organoid phenotypes. Moreover, antral biopsies also demonstrated increased parietal cells and lacked G-cells suggesting loss of antral identity. All organoid pathologies were reversed upon CRISPR-mediated correction of the mutation. Conclusion: These patients will now be monitored for the progression of metaplasia and gastrointestinal complications that might be related to the reduced gastric and intestinal endocrine cells. This study demonstrates the utility of organoids in diagnosing uncovered pathologies.

Gastric Peptides—Gastrin and Somatostatin

Chapter

Dec 2019

Gastric acid secretion (i) facilitates digestion of protein as well as absorption of micronutrients and certain medications, (ii) kills ingested microorganisms, including Helicobacter pylori, and (iii) prevents bacterial overgrowth and enteric infection. The principal regulators of acid secretion are the gastric peptides gastrin and somatostatin. Gastrin, the major hormonal stimulant for acid secretion, is synthesized in pyloric mucosal G cells as a 101-amino acid precursor (preprogastrin) that is processed to yield biologically active amidated gastrin-17 and gastrin-34. The C-terminal active site of gastrin (Trp-Met-Asp-Phe-NH2 ) binds to gastrin/CCK2 receptors on parietal and, more importantly, histamine-containing enterochromaffin-like (ECL) cells, located in oxyntic mucosa, to induce acid secretion. Histamine diffuses to the neighboring parietal cells where it binds to histamine H2 -receptors coupled to hydrochloric acid secretion. Gastrin is also a trophic hormone that maintains the integrity of gastric mucosa, induces proliferation of parietal and ECL cells, and is thought to play a role in carcinogenesis. Somatostatin, present in D cells of the gastric pyloric and oxyntic mucosa, is the main inhibitor of acid secretion, particularly during the interdigestive period. Somatostatin exerts a tonic paracrine restraint on gastrin secretion from G cells, histamine secretion from ECL cells, and acid secretion from parietal cells. Removal of this restraint, for example by activation of cholinergic neurons during ingestion of food, initiates and maximizes acid secretion. Knowledge regarding the structure and function of gastrin, somatostatin, and their respective receptors is providing novel avenues to better diagnose and manage acid-peptic disorders and certain cancers. Published 2020. Compr Physiol 10:197-228, 2020.

Lipopolysaccharides From Non-Helicobacter pylori Gastric Bacteria Potently Stimulate Interleukin-8 Production in Gastric Epithelial Cells

Article

Mar 2019

BACKGROUND Gastric acid secretion is compromised in chronic Helicobacter pylori (H. pylori) infection allowing overgrowth of non-H. pylori gastric bacteria (NHGB) in the stomach. METHODS NHGB were isolated from gastric mucosa in selective media and further characterized with biochemical methods and 16S rRNA gene sequencing. Human gastric tissues were studied with indirect immunofluorescence with antibodies against H. pylori and Neisseria subflava (N. subflava). Gastric epithelial cell lines were cocultured with bacteria or incubated with lipopolysaccharides isolated from NHGB, and interleukin-8 released in the media was measured by enzyme-linked immunosorbent assay. Expression of Toll-like receptor (TLR)2, TLR4, it's coreceptor myeloid differentiation factor 2 (MD2), and CD14 in gastric cells was investigated by immunofluorescence microscopy and reverse transcriptase-polymerase chain reaction. RESULTS Haemophilus species, Neisseria species, Fusobacterium species, and Veillonella species were predominant Gram-negative bacteria coinfected with H. pylori. Lipopolysaccharides from N. subflava potently stimulated interleukin-8 secretion in MKN45 cells which was cancelled by preincubation with polymyxin B. TLR2, TLR4, CD14, and myeloid differentiation factor 2 were expressed in MKN45 cells, though their levels of expression were low. N. subflava adhered to MKN45 cells in vitro and colocalized with H. pylori in the human gastric mucosa. CONCLUSIONS Our data suggest that N. subflava colonized in the gastric mucosa contribute to gastric inflammation during chronic H. pylori gastritis. TRANSLATIONAL IMPACT NHGB may perpetuate gastric inflammation and accelerate neoplastic progression in the hypochlorhydric stomach.

Clinical Manifestations of Helicobacter pylori–Negative Gastritis

Article

Jan 2017

Objectives: There are data to suggest the existence of non-H. pylori gastritis. However, the risk factors and clinical course for H. pylori-negative gastritis remain unclear. We aimed to examine the prevalence and determinants of H. pylori-negative gastritis in a large multiethnic clinical population. Method: We conducted a cross-sectional study among patents scheduled for an elective esophagastroduodenoscopy or attending selected primary care clinics and eligible for screening colonoscopy at a single VA medical center. We identified cases of H. pylori-negative gastritis, H. pylori-positive gastritis, and H. pylori-negative non-gastritis, where gastritis was defined by the presence of neutrophils and/or mononuclear cells. Risk factors for H. pylori-negative gastritis were analyzed in logistic regression models. Results: 1240 patients had information from all biopsy sites; of whom 695 (56.0%) had gastritis. H. pylori-negative gastritis was present in 123 patients (9.9% of all study subjects and 17.7% of all patients with gastritis). Among all patients with gastritis, African Americans were statistically significantly less likely than non-Hispanic whites to have H. pylori-negative gastritis (Odds ratio [OR] = 0.25, 95% confidence interval [CI] = 0.14-0.43). Conversely, PPI users were more likely to have H. pylori-negative gastritis than H. pylori-positive gastritis compared with non-users (OR = 2.02, 95%CI = 1.17-3.49). The cumulative incidence of gastric erosions and ulcers were higher in patients with H. pylori-negative gastritis than H. pylori-negative non-gastritis. Conclusions: We found that H. pylori-negative gastritis was present in approximately 18% of gastritis patients. The potential for H. pylori-negative gastritis to progress or the risk of gastric cancer of those with gastric mucosal atrophy/intestinal metaplasia remains unclear.

Gastritis - Facts and doubts

Article

Full-text available

Jan 2016
PRZ GASTROENTEROL

Introduction: Many clinicians consider chronic gastritis to be equivalent to Helicobacter pylori infection. However, it is known that there are numerous other causes of the condition. Aim: Determination of the incidence of gastritis in patients with dyspepsia referred for diagnostic endoscopy of the upper part of the digestive tract, identification of the parts of the stomach most frequently affected by the inflammation, as well as the impact of an insufficient number of collected samples on the correct diagnosis. Material and methods: Upper gastrointestinal endoscopy due to dyspepsia was performed in 110 patients. In the course of gastroscopy two biopsy specimens were collected for histopathological examination and towards H. pylori infection from the lesser and greater curvature in the antrum 3 cm from the pyloric sphincter, in the body - 4 cm proximally to the stomach angular incisure on the lesser curvature, and in the middle of the greater curvature, as well as in the subcardiac region on the side of the lesser and greater curvature. Results: In patients with dyspepsia H. pylori-negative chronic gastritis is more common than gastritis with accompanying H. pylori infection. Collection of too small a number of biopsy specimens results in failure to detect inflammatory changes and/or H. pylori infection, which may be limited to one part of the stomach. Biopsy specimens of gastric mucosa should be collected in compliance with the assumptions of the Sydney System. Helicobacter pylori infection in people with dyspepsia is now being reported more rarely than in the past (36%). Conclusions: In patients with dyspepsia chronic H. pylori-negative gastritis is more common than gastritis with an accompanying H. pylori infection. Helicobacter pylori infection is not always equivalent to the presence of chronic gastritis.

Transgenic and gene knockout mice in gastric cancer research

Article

Full-text available

Oct 2016

Mouse models are useful tool for carcinogenic study. They will greatly enrich the understanding of pathogenesis and molecular mechanisms for gastric cancer. However, only few of mice could develop gastric cancer spontaneously. With the development and improvement of gene transfer technology, investigators created a variety of transgenic and knockout/knockin mouse models of gastric cancer, such as INS-GAS mice and gastrin knockout mice. Combined with helicobacter infection and carcinogens treatment, these transgenic/knockout/knockin mice developed precancerous or cancerous lesions, which are proper for gene function study or experimental therapy. Here we review the progression of genetically engineered mouse models on gastric cancer research, and emphasize the effects of chemical carcinogens or infectious factors on carcinogenesis of genetically modified mouse. We also emphasize the histological examination on mouse stomach. We expect to provide researchers with some inspirations on this field.

Gastrin and upper GI cancers

Article

Aug 2016

Gastrin was initially identified as the hormone primarily responsible for gastric acid secretion, but was subsequently shown to be a growth factor for the proximal stomach, acting through the gastrin receptor CCK2R. Studies in the past several decades have explored the role of gastrin, along with its incompletely processed precursors, in cancer development. The growth in long-term PPI use has frequently led to elevations in serum gastrin levels in patients with upper GI disease, including GERD, peptic ulcers, and chronic gastritis. However, while accumulated evidence has shown that gastrin likely does not promote-and may even suppress-distal antral gastric cancer, questions have now arisen regarding possible effects of gastrin on the development of gastric cardia cancer or esophageal adenocarcinoma at gastroesophageal junction. Here, we provide an overview of the possible roles of these gastrin peptides in upper GI cancer.

Virulence of Helicobacter pylori infection and gastric cancer: lessons from mouse models

Chapter

Jan 2003

Although discovered only recently, Helicobacter pylori is now considered the prototype for bacteria capable of promoting cancer in humans. Shortly after its isolation and identification in 1982, Marshall and Warren quickly recognized that the human pathogen H. pylori might be responsible for both peptic ulcer disease and gastric cancer. The bacterium was strongly associated with chronic active gastritis, long known to precede cancer, and infection with the organism was endemic in those parts of the world where gastric cancer is prevalent. Given the widespread prevalence of H. pylori infection throughout the world, it was understandable that the proposed link between the bacteria and stomach cancer met with some initial scepticism. Nevertheless, evidence in support of this theory has continued to accumulate and the link between H. pylori and gastric cancer has become less debatable. The H. pylori-gastric cancer connection is now supported by multiple lines of evidence, ranging from clinical epidemiological investigations to prospective observational studies to animal models. However, at a basic level many questions remain. Gastric cancer is the eventual outcome in only 1% of infected individuals; why then does gastric cancer develop in some individuals (but not others), and how does chronic H. pylori infection lead to gastric cancer?

Imbalance of Gastrointestinal Microbiota in the Pathogenesis of Helicobacter pylori -Associated Diseases

Article

Feb 2016
HELICOBACTER

The development of new nucleotide sequencing techniques and advanced bioinformatics tools has opened the field for studying the diversity and complexity of the gastrointestinal microbiome independent of traditional cultural methods. Owing largely to the gastric acid barrier, the human stomach was long thought to be sterile. The discovery of Helicobacter pylori, the gram-negative bacterium that infects upwards of 50% of the global population, has started a major paradigm shift in our understanding of the stomach as an ecologic niche for bacteria. Recent sequencing analysis of gastric microbiota showed that H. pylori was not alone and the interaction of H. pylori with those microorganisms might play a part in H. pylori-associated diseases such as gastric cancer. In this review, we summarize the available literature about the changes of gastrointestinal microbiota after H. pylori infection in humans and animal models, and discuss the possible underlying mechanisms including the alterations of the gastric environment, the secretion of hormones and the degree of inflammatory response. In general, information regarding the composition and function of gastrointestinal microbiome is still in its infancy, future studies are needed to elucidate whether and to what extent H. pylori infection perturbs the established microbiota. It is assumed that clarifying the role of gastrointestinal communities in H. pylori-associated diseases will provide an opportunity for translational application as a biomarker for the risk of serious H. pylori diseases and perhaps identify specific organisms for therapeutic eradication.

Molecular Mechanisms of Inflammation-Induced Cancer: T-cells as Targets for Prevention and Cure of Helicobacter-Related Gastric Preneoplasia

Article

Jan 2010

Isabella M Toller

Gastrointestinal Hormones

Chapter

Dec 2006

Graham J. Dockray

Wechselwirkungen der intestinalen Mikroflora und des angeborenen Immunsystems bei entzündlichen Erkrankungen im Gastrointestinaltrakt

Thesis

Sep 2007

André Fischer

Die chronisch-entzündlichen Darmerkrankungen Morbus Crohn und Colitis ulzerosa sind wiederkehrende, nicht heilbare, immunvermittelte Krankheiten unklarer Ursache. Genetische Prädisposition und Umweltfaktoren können die Barrierefunktion der Darmmukosa stören, so dass eine überschiessende Entzündungsreaktion folgt, die durch kommensale Bakterien der normalen Darmflora verstärkt wird. Die Infektion mit H. pylori im Magen kann zu Gastritis, Ulkuskrankheit und der Entstehung von MALT-Lymphomen und Magenkarzinomen führen. An der Erkennung von bakteriellen Bestandteilen im Gastrointestinaltrakt sind Toll-like-Rezeptoren (TLR), als Komponenten des angeborenen Immunsystems maßgeblich beteiligt. In der vorliegenden Arbeit wurden Veränderungen der Bakterienflora bei Ileitis, Colitis und bei Vorliegen einer H. pylori-Infektion im Mausmodell untersucht. Durch eine globale Florenanalyse mit klassischen mikrobiologischen und molekularbiologischen Techniken konnte gezeigt werden, dass die Konzentrationen an Gram-negativen Stäbchenbakterien während der Entzündung in Ileum und Colon anstiegen. Die bakteriellen Faktoren, die eine Ileitis induzierten, wurden durch den Einsatz von gnotobiotischen TLR-defizienten Mäusen mit definierter bakterieller Rekolonisierung ermittelt. Hierbei zeigte sich, dass eine Ileitis durch das LPS von akkumulierenden E. coli über die TLR4-vermittelte Signaltransduktion verstärkt wurde. Die Entzündungsreaktionen konnten durch Behandlung mit Antibiotika oder dem LPS-Antagonisten Polymyxin B gebessert werden. In Folge einer H. pylori-Infektion kam es im Mausmagen zu einer erhöhten Diversität der Bakterienflora durch die Besiedelung mit Bakterienarten, die normalerweise das Colon kolonisieren. Eine derartige Florenverschiebung konnte durch eine Vakzinierung gegen H. pylori verhindert werden. Die Tiermodelle zur T. gondii-induzierten Ileitis und DSS-Colitis erlauben eine reproduzierbare Analyse entzündungsrelevanter Komponenten und damit die Möglichkeit, therapeutische Ansatzpunkte, wie z.B. den Einsatz von Lipopolysaccharid-Inhibitoren, die Blockade von TLR4 oder dem LPS-Bindeprotein oder den Einsatz von Probiotika, unter definierten Bedingungen zu analysieren.

Differences in Gastric Mucosal Microbiota Profiling in Patients with Chronic Gastritis, Intestinal Metaplasia, and Gastric Cancer Using Pyrosequencing Methods

Article

Jul 2014

Background: Helicobacter pylori (H. pylori) infection plays an important role in the early stage of cancer development. However, various bacteria that promote the synthesis of reactive oxygen and nitrogen species may be involved in the later stages. We aimed to determine the microbial composition of gastric mucosa from the patients with chronic gastritis, intestinal metaplasia, and gastric cancer using 454 GS FLX Titanium. Methods: Gastric mucosal biopsy samples were collected from 31 patients during endoscopy. After the extraction of genomic DNA, variable region V5 of the 16S rRNA gene was amplified. PCR products were sequenced using 454 high-throughput sequencer. The composition, diversity, and richness of microbial communities were compared between three groups. Results: The composition of H. pylori-containing Epsilonproteobacteria class appeared to be the most prevalent, but the relative increase in the Bacilli class in the gastric cancer group was noticed, resulting in a significant difference compared with the chronic gastritis group. By analyzing the Helicobacter-dominant group at a family level, the relative abundance of Helicobacteraceae family was significantly lower in the gastric cancer group compared with chronic gastritis and intestinal metaplasia groups, while the relative abundance of Streptococcaceae family significantly increased. In a UPGMA clustering of Helicobacter-dominant group based on UniFrac distance, the chronic gastritis group and gastric cancer group were clearly separated, while the intestinal metaplasia group was distributed in between the two groups. The evenness and diversity of gastric microbiota in the gastric cancer group was increased compared with other groups. Conclusions: In Helicobacter predominant patients, the microbial compositions of gastric mucosa from gastric cancer patients are significantly different to chronic gastritis and intestinal metaplasia patients. These alterations of gastric microbial composition may play an important, as-yet-undetermined role in gastric carcinogenesis of Helicobacter predominant patients.

Indian Hedgehog Mediates Gastrin-Induced Proliferation in Stomach of Adult Mice

Article

May 2014

Background & aims: Loss of expression of Sonic Hedgehog (Shh) from parietal cells results in hypergastrinemia in mice, accompanied by increased expression of Indian Hedgehog (Ihh) and hyperproliferation of surface mucous cells. We investigated whether hypergastrinemia induces gastric epithelial proliferation by activating Ihh signaling in mice. Methods: We studied mice with parietal cell-specific deletion of Shh (PC-Shh(KO)) and hypergastrinemia, crossed with gastrin-deficient (GKO) mice (PC-Shh(KO)/GKO). When mice were 3-4 months old, gastric tissues were collected and analyzed by histology, for incorporation of bromodeoxyuridine, and for expression of the surface mucous cell marker Ulex europaeus. PC-Shh(KO)/GKO mice were given gastrin infusions for 7 days; gastric surface epithelium was collected and expression of Ihh was quantified by laser capture microdissection followed by quantitative reverse transcriptase polymerase chain reaction. Mouse stomach-derived organoids were incubated with or without inhibitors of WNT (DKK1) or Smoothened (vismodegib) and then cocultured with immortalized stomach mesenchymal cells, to assess proliferative responses to gastrin. Results: Gastric tissues from PC-Shh(KO)/GKO mice with hypergastrinemia had an expanded surface pit epithelium, indicated by a significant increase in numbers of bromodeoxyuridine- and Ulex europaeus-positive cells, but there was no evidence for hyperproliferation. Gastrin infusion of PC PC-Shh(KO)/GKO mice increased expression of Ihh and proliferation within the surface epithelium compared with mice given infusions of saline. In gastric organoids cocultured with immortalized stomach mesenchymal cells, antagonists of WNT and Smoothened inhibited gastrin-induced proliferation and WNT activity. Activity of WNT in media collected from immortalized stomach mesenchymal cells correlated with increased expression of glioma-associated oncogene homolog 1, and was inhibited by DKK1 or vismodegib. Conclusions: Ihh signaling mediates gastrin-induced proliferation of epithelial cells in stomachs of adult mice.

Helicobacter pylori-Negative Gastritis: Prevalence and Risk Factors

Article

Full-text available

Nov 2012
AM J GASTROENTEROL

Objectives: Recent studies using histology alone in select patients have suggested that Helicobacter pylori-negative gastritis may be common. The objective of this study was to investigate the prevalence of H. pylori among individuals with histologic gastritis. Methods: Subjects between 40 and 80 years underwent elective esophagogastroduodenoscopy at a VA Medical Center. Gastric biopsies were mapped from seven prespecified sites (two antrum, four corpus, and one cardia) and graded by two gastrointestinal pathologists, using the Updated Sydney System. H. pylori-negative required four criteria: negative triple staining at all seven gastric sites, negative H. pylori culture, negative IgG H. pylori serology, and no previous treatment for H. pylori. Data regarding tobacco smoking, alcohol drinking, nonsteroidal anti-inflammatory drug, and proton pump inhibitor (PPI) use were obtained by questionnaire. Results: Of the 491 individuals enrolled, 40.7% (200) had gastritis of at least grade 2 in at least one biopsy site or grade 1 in at least two sites. Forty-one (20.5%) had H. pylori-negative gastritis; most (30 or 73.2%) had chronic gastritis, five (12.2%) had active gastritis, and six (14.6%) had both. H. pylori-negative gastritis was approximately equally distributed in the antrum, corpus, and both antrum and corpus. Past and current PPI use was more frequent in H. pylori-negative vs. H. pylori-positive gastritis (68.2% and 53.8%; P=0.06). Conclusions: We used multiple methods to define non-H. pylori gastritis and found it in 21% of patients with histologic gastritis. While PPI use is a potential risk factor, the cause or implications of this entity are not known.

The Innovative Potential of Lactobacillus rhamnosus LR06, Lactobacillus pentosus LPS01, Lactobacillus plantarum LP01, and Lactobacillus delbrueckii Subsp. delbrueckii LDD01 to Restore the “Gastric Barrier Effect” in Patients Chronically Treated With PPI: A Pilot Study

Article

Oct 2012
J CLIN GASTROENTEROL

: Gastroesophageal reflux disease is a very widespread condition. In Europe, it is estimated that about 175 million people suffer from this disease and have to chronically take drugs to increase gastric pH. The proton pump inhibitors (PPIs) such as omeprazole, lansoprazole, and esomeprazole are the most widely used drug typology in this regard. However, the inhibition of normal gastric acid secretion has important side effects, the most important being bacterial overgrowth in the stomach and duodenum with a concentration of >10 viable cells/mL. As a major consequence of this, many harmful or even pathogenic bacteria contained in some foods could survive the gastric transit and colonize either the stomach itself, the duodenum, or the gut, where they could establish acute and even chronic infections with unavoidable consequences for the host's health. In other words, the "gastric barrier effect" is strongly reduced or even disrupted. To date, there are no real strategies to deal with this widespread, although still relatively little known, problem. The aim of this study was to confirm the gastric bacterial overgrowth in long-term PPI consumers and to assess the efficacy of some probiotic bacteria, belonging to both genera Lactobacillus and Bifidobacterium, in the reduction of gastric and duodenal bacterial overgrowth, therefore partially restoring the gastric barrier effect against foodborne pathogenic bacteria. : For this purpose, probiotics with a strong demonstrated inhibitory activity on gram-negative bacteria, such as Escherichia coli, were tested in a human intervention trial involving a total of 30 subjects treated with PPIs for either 3 to 12 consecutive months (short-term) or >12 consecutive months (long-term). An additional 10 subjects not taking PPIs were enrolled and used as a control group representing the general population. Four selected probiotics Probiotical SpA (Novara, Italy), namely Lactobacillus rhamnosus LR06 (DSM 21981), Lactobacillus pentosus LPS01 (DSM 21980), Lactobacillus plantarum LP01 (LMG P-21021), and Lactobacillus delbrueckii subsp. delbrueckii LDD01 (DSM 22106) were administered for 10 days to 10 subjects treated with PPIs for >12 months (group B). In the 60 mg formulation, N-acetylcysteine was included as well in light of its well-known mechanical effects on bacterial biofilms. Gastroscopies were performed at the beginning of the study (d0) in all the groups (A, B, C, and D) and after 10 days (d10) in group B only; that is, at the end of probiotics intake. The total viable cells and total Lactobacillus were quantified in gastric juice and duodenal brushing material from all subjects. The results were compared among all the groups and with the control subjects (group D) to confirm the bacterial overgrowth. A comparison was made also between d0 and d10 in group B to quantify the efficacy of the 4 probiotics administered for 10 days. Fecal samples were collected from all groups at d0, including subjects not treated with PPIs, and in group B only at d10. Specific bacterial classes, namely enterococci, total coliforms, E. coli, molds, and yeasts were quantified in all fecal specimens. : The results collected confirmed the strong bacterial overgrowth in the stomach and duodenum of people treated with PPIs compared with subjects with a normal intragastric acidity. It is also worth noting that the bacterial cell counts in subjects who underwent a long-term treatment with a PPI were greater than the results from subjects taking these drugs for 3 to 12 months. The intake of 4 specific probiotic strains with a marked antagonistic activity towards 5 E. coli bacteria, including the enterohaemorrhagic O157:H7 strain, and an effective amount of N-acetylcysteine (NAC) was able to significantly reduce bacterial overgrowth in long-term PPI-treated subjects. Total lactobacilli represented the major percentage of bacterial counts, thus demonstrating the ability of such bacteria to colonize the stomach and the duodenum, at least temporarily, and to consequently restore the gastric barrier effect. A significant decrease in fecal enterococci, total coliforms, E. coli, molds, and yeasts in subjects treated with PPIs was recorded at the end of probiotics supplementation (d10) compared with baseline (d0) in group B. This is a further confirmation of the barrier effect also exerted at the stomach level. : PPIs are the most widely sold and used drugs in the world. However, the chronic use of these pharmacological molecules exposes the subject to the risk of foodborne infections as most pathogens are able to survive the gastric transit in a condition of significantly decreased acidity.

Role of Host Genetic Susceptibility in the Pathogenesis of Gastric Cancer

Chapter

Feb 2009

Emad El-Omar

Atrophy and Altered Mesenchymal—Epithelial Signaling Preceding Gastric Cancer

Chapter

Feb 2009

Chronic inflammation in the stomach (gastritis) induces gastric atrophy characterized by the loss of the acid-secreting oxyntic glands. Although the initial report of phenotypic changes that precede gastric cancer suggest that these steps occur sequentially (Correa et al. 1975), whether atrophy precedes metaplasia or occurs concurrently is unclear. Nevertheless, the metaplastic cell that begins to repopulate the gastric epithelium under hypochlorhydric conditions is a mucous cell of gastric or intestinal origin (Goldenring and Nomura 2006; Kang et al. 2005; Nomura et al. 2004; Oshima et al. 2006). Although Helicobacter pylori infection is the major reason chronic inflammation develops in the stomach, the molecular networks linking chronic inflammation to the atrophic/metaplastic changes are not well understood. This chapter reviews the causes of gastric atrophy and highlights the role that some activated signaling pathways have in committing the mucosa to neoplastic transformation. © 2009 Springer Science + Business Media, LLC. All rights reserved.

Helicobacter pylori CagL dependent induction of gastrin expression via a novel αVβ5-integrin-integrin linked kinase signalling complex

Article

Jan 2012
GUT

One of the most important hormones in the human stomach is the peptide gastrin. It is mainly required for the regulation of gastric pH but is also involved in growth and differentiation of gastric epithelial cells. In Helicobacter pylori infected patients, gastrin secretion can be upregulated by the pathogen, resulting in hypergastrinaemia. H pylori induced hypergastrinaemia is described as being a major risk factor for the development of gastric adenocarcinoma. In this study, the upstream receptor complex and bacterial factors involved in H pylori induced gastrin gene expression were investigated, utilising gastric epithelial cells which were stably transfected with a human gastrin promoter luciferase reporter construct. Integrin linked kinase (ILK) and integrin β5, but not integrin β1, played an important role in gastrin promoter activation. Interestingly, a novel CagL/integrin β5/ILK signalling complex was characterised as being important for H pylori induced gastrin expression. On interaction of H pylori with αvβ(5)-integrin and ILK, the epidermal growth factor receptor (EGFR)→Raf→mitogen activated protein kinase kinase (MEK)→extracellular signal regulated kinase (Erk) downstream signalling cascade was identified which plays a central role in H pylori gastrin induction. The newly discovered recognition receptor complex could be a useful target in treating precancerous conditions triggered by H pylori induced hypergastrinaemia.

Mo1108 Gastric Sonic Hedgehog Acts as a Macrophage Chemoattractant During the Development of the Immune Response to Helicobacter pylori Infection

Article

Jan 2012

Macrophages mediate the epithelial response to Helicobacter pylori and are involved in the development of gastritis. Sonic Hedgehog (Shh) regulates gastric epithelial differentiation and function, but little is known about its immunoregulatory role in the stomach. We investigated whether gastric Shh acts as a macrophage chemoattractant during the innate immune response to H pylori infection. Mice with parietal cell-specific deletion of Shh (PC-Shh(KO)) and control mice were infected with H pylori. Levels of gastric Shh, cytokines, and chemokines were assayed by quantitative reverse-transcriptase polymerase chain reaction or by a Luminex-based multiplex assay 2, 7, or 180 days after infection. Circulating concentrations of Shh were measured by enzyme-linked immunosorbent assay. Bone marrow chimera experiments were performed with mice that have myeloid cell-specific deletion of the Hedgehog signal transduction protein Smoothened (LysMCre/Smo(KO)). Macrophage recruitment was measured in gastric tissue and peripheral blood by fluorescence-activated cell sorting analysis. Control mice infected with H pylori for 6 months developed an inflammatory response characterized by infiltration of CD4(+) T cells and increased levels of interferon gamma and interleukin 1β in the stomach. PC-Shh(KO) mice did not develop gastritis, even after 6 months of infection with H pylori. Control mice had increased concentrations of Shh, accompanied by the recruitment of CD11b(+)F4/80(+)Ly6C(high) macrophages 2 days after infection. Control mice that received bone marrow transplants from control mice had an influx of macrophages to the gastric mucosa in response to H pylori infection; this was not observed in H pylori-infected control mice that received bone marrow transplants from LysMCre/Smo(KO) mice. H pylori induces release of Shh from the stomach; Shh acts as a macrophage chemoattractant during initiation of gastritis.

Gastric Secretion

Article

Sep 2011
CURR OPIN GASTROEN

Mitchell L. Schubert

The review summarizes the past year's literature regarding the regulation of gastric exocrine and endocrine secretion, both basic science and clinical. Gastric acid secretion is an elaborate and dynamic process that is regulated by neural (efferent and afferent), hormonal (e.g. gastrin), and paracrine (e.g. histamine, ghrelin, somatostatin) pathways as well as mechanical (e.g. distension) and chemical (e.g. amino acids) stimuli. Secretion of hydrochloric acid (HCl) by parietal cells involves translocation of HK-ATPase-containing cytoplasmic tubulovesicles to the apical membrane with subsequent electroneutral transport of hydronium ions in exchange for potassium. The main apical potassium channel is KCNQ1 which, when activated, assembles with its β-subunit KCNE2 to function as a constitutively open, voltage-insensitive, and acid-resistant luminal potassium channel. Proton pump inhibitors block acid secretion by covalently binding to cysteine residues accessible from the luminal surface of the HK-ATPase. Potassium-competitive ATPase blockers (P-CABs) act by competing for K on the luminal surface of HK-ATPase. As they are acid-stable and do not require acid-dependent activation, P-CABs hold promise for rapid and prolonged inhibition of acid secretion. We continue to make progress in our understanding of the physiologic regulation of gastric acid secretion. A better understanding of the pathways and mechanisms regulating acid secretion should lead to improved management of patients with acid-induced disorders.

Role of Indigenous Lactobacilli in Gastrin-Mediated Acid Production in the Mouse Stomach

Article

Full-text available

Jul 2011
APPL ENVIRON MICROB

It is known that the stomach is colonized by indigenous lactobacilli in mice. The aim of this study was to examine the role of such lactobacilli in the development of the stomach. For a DNA microarray analysis, germ-free BALB/c mice were orally inoculated with 109 CFU lactobacilli, and their stomachs were excised after 10 days to extract RNA. As a result, lactobacillus-associated gnotobiotic mice showed dramatically decreased expression of the gastrin gene in comparison to germ-free mice. The mean of the log2 fold change in the gastrin gene was −4.3. Immunohistochemistry also demonstrated the number of gastrin-positive (gastrin+) cells to be significantly lower in the lactobacillus-associated gnotobiotic mice than in the germ-free mice. However, there was no significant difference in the number of somatostatin+ cells in these groups of mice. Consequently, gastric acid secretion also decreased in the mice colonized by lactobacilli. In addition, an increase in the expression of the genes related to muscle system development, such as nebulin and troponin genes, was observed in lactobacillus-associated mice. Moreover, infection of germ-free mice with Helicobacter pylori also showed the down- and upregulation of gastrin and muscle genes, respectively, in the stomach. These results thus suggested that indigenous lactobacilli in the stomach significantly affect the regulation of gastrin-mediated gastric acid secretion without affecting somatostatin secretion in mice, while H. pylori also exerts such an effect on the stomach.

Histamine 3 receptor activation mediates inhibition of acid secretion during Helicobacter -induced gastritis

Article

Full-text available

Dec 2010

To test the hypothesis that histamine 3 receptor (H3R) activation during Helicobacter infection inhibits gastric acid secretion in vivo and in vitro. Helicobacter felis (H. felis) infected and uninfected C57Bl/6 mice were infused with either PBS or the H3 receptor antagonist thioperamide (THIO) for 12 wk. After treatment, mice were analyzed for morphological changes and gastric acid content. Total RNA was prepared from the stomachs of each group and analyzed for changes in somatostatin and gastrin mRNA abundance by real time-polymerase chain reaction (RT-PCR). Location of H3 receptors in the stomach was analyzed by co-localization using antibodies specific for the H3 receptor and parietal cell marker H(+), K(+)-ATPase β subunit. Inflammation and parietal cell atrophy was observed after 12 wk of H. felis infection. Interestingly, treatment with the H3R antagonist thioperamide (THIO) prior to and during infection prevented H. felis-induced inflammation and atrophy. Compared to the uninfected controls, infected mice also had significantly decreased gastric acid. After eradication of H. felis with THIO treatment, gastric acidity was restored. Compared to the control mice, somatostatin mRNA abundance was decreased while gastrin gene expression was elevated during infection. Despite elevated gastric acid levels, after eradication of H. felis with THIO, somatostatin mRNA was elevated whereas gastrin mRNA was suppressed. Immunofluorescence revealed the presence of H3 receptors on the parietal cells, somatostatin-secreting D-cells as well as the inflammatory cells. This study shows that during H. felis infection, gastric acidity is suppressed as a consequence of an inhibitory effect on the parietal cell by H3R activation. The stimulation of gastric mucosal H3Rs increases gastrin expression and release by inhibiting release of somatostatin.

Impaired gastric acid secretion in gastrin-deficient mice

Article

Full-text available

Mar 1998
Am J Physiol

To further understand the role of the peptide hormone gastrin in the development and function of the stomach, we have generated gastrin-deficient mice by gene targeting in embryonic stem cells. Mutant mice were viable and fertile, without obvious visible abnormalities. However, gastric function was severely affected by the loss of gastrin. Basal gastric acid secretion was abolished and could not be induced by histamine, carbachol, or gastrin. Histological analysis revealed alterations in the two cell types primarily involved in acid secretion, parietal and enterochromaffin-like (ECL) cells. Parietal cells were reduced in number with an accumulation of immature cells lacking H(+)-K(+)-adenosinetriphosphatase (H(+)-K(+)-ATPase). ECL cells were positioned closer to the base of the gastric glands, with markedly lower expression of histidine decarboxylase. Gastrin administration for 6 days reversed the effects of the gastrin deficiency, leading to an increase in the number of mature, H(+)-K(+)-ATPase-positive parietal cells and a partial restoration of acid secretion. The results show that gastrin is critically important for the function of the acid secretory system.

Modulation of the intestinal flora of mice by parenteral treatment with broad-spectrum cephalosporins

Article

Full-text available

Jun 1991

A study was performed to determine the effect of parenteral treatment with four broad-spectrum cephalosporins (cefoperazone, ceftriaxone, ceftazidime, and cefepime) on the number of aerobic gram-negative rods and on the outgrowth of Candida albicans and a multiresistant strain of Citrobacter freundii in the feces of mice. The estimated fractions of a parenteral dose that were excreted into the gastrointestinal tract were 0.37 for cefoperazone, 0.11 for ceftriaxone, 0.03 for ceftazidime, and 0.002 for cefepime. All four cephalosporins significantly decreased the number of aerobic gram-negative rods in the feces, and virtually all gram-negative rods were eliminated at high doses of cefoperazone, ceftazidime, and ceftriaxone. Furthermore, at high doses these three compounds led to a significant increase of the outgrowth of resistant Citrobacter freundii. The outgrowth of Candida albicans was increased at high doses of cefoperazone and ceftriaxone, whereas ceftazidime and cefepime did not have this effect. The most profound changes in the gastrointestinal ecology were observed during treatment with high doses of cefoperazone. The results suggest that the colonization resistance of the gastrointestinal tract can be substantially decreased by parenteral treatment with cefoperazone and, to a lesser extent, with ceftriaxone and ceftazidime.

Helicobacter pylori Infection and the Risk of Gastric Carcinoma

Article

Full-text available

Nov 1991

Infection with Helicobacter pylori has been linked with chronic atrophic gastritis, an inflammatory precursor of gastric adenocarcinoma. In a nested case-control study, we explored whether H. pylori infection increases the risk of gastric carcinoma. From a cohort of 128,992 persons followed since the mid-1960s at a health maintenance organization, 186 patients with gastric carcinoma were selected as case patients and were matched according to age, sex, and race with 186 control subjects without gastric carcinoma. Stored serum samples collected during the 1960s were tested for IgG antibodies to H. pylori by enzyme-linked immunosorbent assay. Data on cigarette use, blood group, ulcer disease, and gastric surgery were obtained from questionnaires administered at enrollment. Tissue sections and pathology reports were reviewed to confirm the histologic results. The mean time between serum collection and the diagnosis of gastric carcinoma was 14.2 years. Of the 109 patients with confirmed gastric adenocarcinoma (excluding tumors of the gastroesophageal junction), 84 percent had been infected previously with H. pylori, as compared with 61 percent of the matched control subjects (odds ratio, 3.6; 95 percent confidence interval, 1.8 to 7.3). Tumors of the gastroesophageal junction were not linked to H. pylori infection, nor were tumors in the gastric cardia. H. pylori was a particularly strong risk factor for stomach cancer in women (odds ratio, 18) and blacks (odds ratio, 9). A history of gastric surgery was independently associated with the development of cancer (odds ratio, 17; P = 0.03), but a history of peptic ulcer disease was negatively associated with subsequent gastric carcinoma (odds ratio, 0.2; P = 0.02). Neither blood group nor smoking history affected risk. Infection with H. pylori is associated with an increased risk of gastric adenocarcinoma and may be a cofactor in the pathogenesis of this malignant condition.

Parasitism by the "slow" bacterium Helicobacter pylori leads to altered gastric homeostasis and neoplasia

Article

Full-text available

Aug 1994

Effect of omeprazole on intragastric bacterial counts, nitrates, nitrites, and N-nitroso compounds

Article

Full-text available

May 1994

Previous studies have suggested that profound inhibition of gastric acid secretion may increase exposure to potentially carcinogenic N-nitroso compounds. The aim of this study was to find out if the proton pump inhibitor omeprazole (20 mg daily) is associated with increased concentrations of potentially carcinogenic N-nitroso compounds in gastric juice. The volume of gastric contents, number of bacteria, and concentrations of nitrates, nitrites, and N-nitroso compounds was determined in gastric aspirates obtained after an overnight fast in 14 healthy volunteers (7M:7F) after one week of treatment with placebo, and one and two weeks' treatment with omeprazole. Median bacterial concentrations were 1.0 x 10(4) (range 5.0 x 10(3)-5.0 x 10(6)) colony forming units (CFU)/ml after one weeks' treatment with placebo and increased significantly to 4.0 x 10(5) (0-3.3 x 10(7)) CFU/ml after two weeks' treatment with omeprazole (p < 0.05). A similar increase was seen in the concentration of nitrate reducing bacteria. There was no difference in the volume of gastric aspirates after treatment with omeprazole when compared with placebo (65 (29-155) ml v 42 (19-194) ml). The concentration of N-nitroso compounds was 0.13 (0-1.0) mumol/l after two weeks of omeprazole, which was not significantly different from that seen with placebo (0.15 (0-0.61) mumol/l). There was also no increase in the concentrations of nitrates or nitrites. It is concluded that omeprazole (20 mg once daily) for two weeks in healthy volunteers is associated with gastric bacterial proliferation but does not increase concentrations of N-nitroso compounds.

Trefoil peptides and the gut

Article

Full-text available

Jun 1993

Nicholas A Wright

Nitrite, N-nitroso compounds, and other analytes in physiological fluids in relation to precancerous gastric lesions

Article

Full-text available

Feb 1996

Levels of gastric juice nitrite, several urinary N-nitroso compounds, and other analytes were examined among nearly 600 residents in an area of Shandong, China, where precancerous gastric lesions are common and rates of stomach cancer are among the world's highest. Gastric juice nitrite levels were considerably higher among those with gastric juice pH values above 2.4 versus below 2.4. Nitrite was detected more often and at higher levels among persons with later stage gastric lesions, especially when gastric pH was high. Of those with intestinal metaplasia, 17.5% had detectable levels of gastric nitrite, while this analyte was detected in only 7.2% of those with less advanced lesions. Relative to those with undetectable nitrite, the odds of intestinal metaplasia increased from 1.5 (95% confidence interval = 0.6-4.1) to 4.1 (95% confidence interval = 1.8-9.3) among those with low and high nitrite concentrations, respectively. Urinary acetaldehyde and formaldehyde levels also tended to be higher among those with more advanced pathology, particularly dysplasia. However, urinary excretion levels of total N-nitroso compounds and several nitrosamino acids differed little among those with chronic atrophic gastritis and intestinal metaplasia and dysplasia, consistent with findings from recent studies in the United Kingdom, France, and Colombia. The data from this high-risk population suggest that elevated levels of gastric nitrite, especially in a high pH environment, are associated with advanced precancerous gastric lesions, although specific N-nitroso compounds were not implicated.

Specific detection of Helicobactor pylori and non-Helicobactor pylori flora in small-and large-cell primary gastric B-cell non-Hodgkin's lymphoma

Article

Full-text available

Jan 1997

Primary gastric non-Hodgkin's lymphomas possibly develop in response to local infection by Helicobacter pylori (H. pylori). We investigated the presence of H. pylori and non-H. pylori flora histologically in small- and large-cell primary gastric lymphoma using a specific staining method. Specimens of 52 cases of primary gastric lymphoma (17 small cell, 35 large cell) were stained with modified Giemsa (MG) and immunohistochemically using a polyclonal antibody against H. pylori (IHC). Thirty-two cases (61.5%) (small cell 76% versus large cell 53%, P > 0.05) showed immunoreactivity for H. pylori in the mucosa surrounding the tumor. Remarkably, there was localization of H. pylori in the neck of the gastric glands in 3 cases. Non-H. pylori flora was seen in 35 cases (76.3%) (small cell 53% versus large cell 74%, P > 0.05). In 20 cases, this non-H. pylori flora was mixed with H. pylori. Five cases showed no bacterial flora at all. (1) Using immunohistochemistry, the prevalence of gastric lymphoma cases with H. pylori (61.5%) approximates that of H. pylori in the normal population. (2) No statistical difference was found between the occurrence of H. pylori and non-H. pylori bacterial flora in small- versus large-cell lymphoma. (3) Our results suggest that H. pylori may not be the only etiologic factor in primary gastric lymphoma.

Bombesin-induced gastrin release from canine G cells is stimulated by Ca2+ but not by protein kinase C, and is enhanced by disruption of rho/cytoskeletal pathways

Article

Full-text available

Oct 1997

Isolated canine G cells in primary culture have been used to study calcium, protein kinase C (PKC), and rho/cytoskeletal-dependent intracellular pathways involved in bombesin- stimulated gastrin release. A method to obtain highly purified G cells by culture (64% G cells) after flow cytometry on elutriated fractions of cells from digested canine gastric antral mucosa has been developed. Pretreatment of G cells with thapsigargin (10(-8)-10(-6) M) and release experiments in Ca2+-containing or -depleted media showed that influx of Ca2+ into the cells and not acute release from intracellular stores plays an important role in bombesin-stimulated gastrin release. Inhibition of PKC by the specific inhibitor GF 109 203X did not affect bombesin-stimulated release. Rho, a small GTP-binding protein that regulates the actin cytoskeleton, is specifically antagonized by Clostridium botulinum C3 exoenzyme. C3 (10 microg/ml) enhanced basal and bombesin-stimulated gastrin release by 315 and 266%, respectively. The importance of the cytoskeleton for regulation of gastrin release was emphasized by a more pronounced release of gastrin when the organization of the actin cytoskeleton was disrupted by cytochalasin D (5 x 10(-)7 and 10(-)6 M). Wortmannin, a potent inhibitor of phosphoinositide-3-kinase, did not alter bombesin-stimulated gastrin release. Thus, it is concluded that bombesin-induced gastrin release from canine G cells is stimulated by Ca2+ but not by PKC, and is enhanced by disruption of rho/cytoskeletal pathways.

Autoimmune gastritis results in disruption of gastric epithelial cell development

Article

Full-text available

Aug 1999
Am J Physiol

We have investigated the underlying basis of the lesion in murine autoimmune gastritis, a model of the human disease pernicious anemia. The disease is mediated by T lymphocytes and characterized by selective depletion of parietal and zymogenic cells from the gastric unit (gland) together with gastric epithelial cell hyperplasia. The gastric units of gastritic stomachs contained 2.3-fold more cells than normal and accumulated rapidly dividing, short-lived gastric epithelial stem cells and mucous neck cells. Most of these immature cells failed to differentiate into end-stage cells but rather appeared to die by apoptosis. We also found no correlation between anti-parietal cell autoantibody titers and the degree of gastric pathology, providing further evidence that autoantibodies do not play a direct role in the pathogenesis of gastritis. Taken together, the normal developmental pathways of the gastric mucosa are disrupted in autoimmune gastritis, resulting in an amplification of immature cell types. The differentiation of these immature cells appears to be blocked, contributing to depletion of end-stage cells. This scenario provides an explanation for depletion of not only parietal cells but also zymogenic cells even though they are not directly targeted by the immune system.

Cellular Immune Responses Are Essential for the Development of Helicobacter felis-Associated Gastric Pathology1

Article

Full-text available

Sep 1999

The bacteria Helicobacter pylori is a major human pathogen that infects over half of the world's population. Infection initiates a series of changes in the gastric mucosa, beginning with atrophic gastritis and leading in some patients to peptic ulcer disease, mucosa-associated lymphomas, and gastric adenocarcinoma. Although this cascade of events clearly occurs, little is known about the role of the host immune response in disease progression. We have utilized the C57BL/6 Helicobacter felis mouse model to critically analyze the role of the adaptive immune response in the development of Helicobacter-associated gastric pathology. Infection of B and T cell-deficient RAG-1-/- mice or T cell-deficient TCRbetadelta-/- mice with H. felis resulted in high levels of colonization, but no detectable gastric pathology. Conversely, infection of B cell-deficient microMT mice resulted in severe gastric alterations identical with those seen in immunocompetent C57BL/6-infected mice, including gastric mucosal hyperplasia and intestinal metaplasia. These results demonstrate that the host T cell response is a critical mediator of Helicobacter-associated gastric pathology, and that B cells and their secreted Abs are not the effectors of the immune-mediated gastric pathology seen after H. felis infection. These results indicate that in addition to specific Helicobacter virulence factors, the host immune response is an important determinant of Helicobacter-associated disease.

Murine Splenocytes Induce Severe Gastritis and Delayed-Type Hypersensitivity and Suppress Bacterial Colonization in Helicobacter pylori-Infected SCID Mice

Article

Full-text available

Oct 1999

The goal of this study was to evaluate the role of host immunity in gastritis and epithelial damage due to Helicobacter pylori. Splenocytes from H. pylori-infected and uninfected C57BL/6 mice were adoptively transferred to H. pylori-infected and uninfected severe combined immunodeficient (SCID) mice. Transfer was verified by flow cytometry, and all mice were evaluated for the presence of delayed-type hypersensitivity (DTH) by footpad inoculation with sterile H. pylori sonicate and for humoral immunity by enzyme-linked immunosorbent assay. The severity of gastritis and gastric epithelial damage was quantified histologically, epithelial proliferation was determined by proliferating cell nuclear antigen staining, and colonization was quantified by culture. C57BL/6 mice, but not nonrecipient SCID mice, developed moderate gastritis in response to H. pylori. In contrast, recipient SCID mice developed severe gastritis involving 50 to 100% of the gastric mucosa and strong DTH responses not present in C57BL/6 mice. DTH, but not serum anti-H. pylori immunoglobulin G, correlated with adoptive transfer, gastritis, and bacterial clearance. Severe gastritis, but not bacterial colonization, was associated with epithelial metaplasia, erosions, and an elevated labeling index. This study demonstrates that (i) adaptive immunity is essential for development of gastritis due to H. pylori in mice, (ii) T-cell-enriched lymphocytes in SCID mice induce DTH and gastritis, which is more severe than donor gastritis, and (iii) the host inflammatory response, not direct bacterial contact, causes epithelial damage. The greater severity of gastritis in recipient SCID mice than in donor C57BL/6 mice suggests that gastritis is due to specific T-cell subsets and/or the absence of regulatory cell subsets in the transferred splenocytes.

Fox JG, Dangler CA, Taylor NS, King A, Koh TJ, Wang TCHigh-salt diet induces gastric epithelial hyperplasia and parietal cell loss, and enhances Helicobacter pylori colonization in C57BL/6 mice. Cancer Res 59: 4823-4828

Article

Full-text available

Nov 1999

A high-salt diet in humans and experimental animals is known to cause gastritis, has been associated with a high risk of atrophic gastritis, and is considered a gastric tumor promoter. In laboratory rodents, salt is known to cause gastritis, and when coadministered, it promotes the carcinogenic effects of known gastric carcinogens. Because Helicobacter pylori has been associated with a progression from gastritis to gastric cancer, we designed a study to determine whether excessive dietary NaCl would have an effect on colonization and gastritis in the mouse model of H. pylori infection. Seventy-two, 8-week-old female C57BL/6 mice were infected with H. pylori strain Sydney, and 36 control mice were dosed with vehicle only. One-half of the infected and control mice were fed a high-salt diet (7.5% versus 0.25%) for 2 weeks prior to dosing and throughout the entire experiment. Twelve infected and 6 control animals from the high-salt and normal diet groups were euthanized at 4, 8, and 16 weeks. At 8 and 16 weeks postinfection (WPI), the colony-forming units per gram of tissue were significantly higher (P < 0.05) in the corpus and antrum of animals in the high-salt diet group compared with those on the normal diet. Quantitative urease was significantly higher (P < 0.05) at 4 and 8 WPI in the corpus and antrum of animals on the high-salt diet when compared with controls. At 16 WPI, mice in both the normal and the high-salt diet groups developed moderate to marked atrophic gastritis of the corpus in response to H. pylori infection. However, the gastric pits of the corpus mucosa in mice on the high-salt diet were elongated and colonized by H. pylori more frequently than those in mice on the normal diet. The high-salt diet was also associated with a significant increase in proliferation in the proximal corpus and antrum and a multifocal reduction in parietal cell numbers in the proximal corpus, resulting in the elongation of gastric pits. We conclude that excessive NaCl intake enhances H. pylori colonization in mice and in humans and that chronic salt intake may exacerbate gastritis by increasing H. pylori colonization. Furthermore, elevated salt intake may potentiate H. pylori-associated carcinogenesis by inducing proliferation, pit cell hyperplasia, and glandular atrophy.

Role of gastrin in gastric cancerogenesis in Helicobacter pylori infected humans

Article

Full-text available

Jan 2000
J PHYSIOL PHARMACOL

Numerous epidemiological studies demonstrated the association between Helicobacter pylori (H. pylori) infection and gastric cancer but the mechanism of the involvement of H. pylori in gastric cancerogenesis remains virtually unknown. This study was designed to determine the seropositivity of H. pylori and cytotoxin associated gene A (CagA), serum gastrin and gastric lumen gastrin levels under basal conditions and following stimulation with histamine in gastric cancer patients and controls. 100 gastric cancer patients aging from 21 to 60 years and 300 gender- and age-adjusted controls hospitalized with non-ulcer dyspepsia (NUD) entered this study. 13C-Urea Breath Test (UBT), serum immunoglobulin (IgG) antibodies to H. pylori and CagA were used to assess the H. pylori infection and serum levels of IL-1beta, IL-8 and TNFalpha were measured by enzyme-linked immunosorbent assay (ELISA) to evaluate the degree of gastric inflammation by H. pylori . Gastrin-17 mRNA and gastrin receptors (CCK(B)) mRNA expression in gastric mucosal samples taken by biopsy from the macroscopically intact fundic and antral mucosa as well as from the gastric tumor was determined using RT-PCR. The overall H. pylori seropositivity in gastric cancer patients at age 21-60 years was about 92%, compared, respectively, to 68%, in controls. A summary odds ratio (OR) for gastric cancer in H. pylori infected patients was about 5.0 . The H. pylori CagA seropositivity in gastric cancer patients was about 58.5% compared to 32.4% in controls, giving the summary OR for gastric cancer in CagA positive patients about 8.0. The prevalence of H. pylori- and H. pylori CagA-seropositivity was significantly higher in cancers than in controls, irrespective of the histology of gastric tumor (intestinal, diffuse or mixed type). Median IL-1beta and IL-8 reached significantly higher values in gastric cancer patients (9.31 and 30.8 pg/ml) than in controls (0.21 and 3.12, respectively). In contrast, median serum gastrin in cancers (as total group) was several folds higher (62.6 pM) than in controls (19.3 pM). Also median luminal gastrin concentration in gastric cancer patients was many folds higher (310 pM) than in controls (20 pM). This study shows for the first time that cancer patients are capable of releasing large amounts of gastrin into the gastric lumen to increase luminal hormone concentration to the level that was recently reported to stimulate the growth of H. pylori. There was no any correlation between plasma gastrin levels and gastric luminal concentration of gastrin suggesting that: 1) luminal gastrin originates from different source than plasma hormone, most probably from the cancer cells, 2) cancer cells are capable of expressing gastrin and releasing it mainly into the gastric juice and 3) the gastric cancer cells are equipped with gastrin-specific (CCK(B)) receptor so they exhibit the self-growth promoting activity in autocrine fashion. This notion is supported by direct detection of gastrin mRNA and gastrin receptor (CCK(B)-receptors) mRNA using RT-PCR in cancer tissue. To our knowledge this is the first study showing an important role of gastrin as self-stimulant of cancer cells in patients infected with H. pylori. Basal and histamine maximally stimulated acid outputs were significantly lower in gastric cancer patients than in controls despite of enhanced gastrin release, particularly in cancer patients and this might reflect the mucosal inflammatory changes (increased serum levels of proinflammtory interleukins - IL-1beta and IL-8), that are known to increase gastrin release. We conclude that: 1) H. pylori infected patients, particularly those showing CagA-seropositivity, are at greatly increased risk of development of gastric cancer, 2) H. pylori-infected cancer patients produce significantly more IL-1beta and IL-8 that might reflect an H. (ABSTRACT TRUNCATED)

Use of Flow Cytometry to Quantify Mouse Gastric Epithelial Cell Populations

Article

Full-text available

Jul 2000

Flow cytometry provides the opportunity to quantify cell populations within a total cell suspension. The quality of flow cytometry is strongly dependent on the isolation of intact viable cells. However, techniques to isolate mouse gastric cells for flow cytometry have not been evaluated. The objective of this study was to develop an effective method for isolating intact viable cells from mouse gastric tissue for flow cytometry. Cells were isolated from mouse stomach and spleen by either enzymatic separation or mechanical dissociation. A Percoll density gradient was used to separate viable cells from cellular debris. Cells were labeled with fluorescently tagged ligand or antibody and analyzed by flow cytometry. According to propidium iodide staining, there was a higher percentage of viable cells after mechanical dissociation (10-20%) compared to enzymatic separation (1%). After Percoll centrifugation there was a further increase in the percent of viable cells (50-80%). Gastrin (G), somatostatin (D), and parietal cells represented 0.6%, 3%, and 8% of the total epithelial cell population, respectively. T and B lymphocytes made up 4% and 2% in the gastric mucosa. Dissociated splenocytes were comprised of 20% T cells and 14% B cells. The ability to reliably resolve a cellular fraction that comprises only 0.6% of the input marks a substantial improvement over morphometric methods. Therefore, mechanical dissociation of the stomach followed by use of a Percoll gradient is the preferred method for isolating viable intact gastric epithelial cells for flow cytometry.

Helicobacter pylori and gastric carcinoma among Japanese American men

Article

Jan 1992

The effect of intra-gastric acidity and flora on the concentration of N-nitroso compounds in the stomach

Article

Feb 2000
EUR J GASTROEN HEPAT

Background: Correa's hypothesis proposes that gastric carcinogenesis is due to atrophic gastritis and hypochlorhydria which permit gastric bacterial colonization, the reduction of dietary nitrates to nitrites and the formation of potentially carcinogenic N-nitroso compounds (NOCs). Objective: To test the hypothesis that omeprazole-induced hypochlorhydria is associated with increased intra-gastric concentrations of nitrate-reducing bacteria (NRB), nitrites and NOCs. Design: Single-blind study in healthy volunteers. Participants: Fourteen healthy subjects (seven female, mean age 24 years), free of Helicobacter pylori infection, received a one-week course of placebo followed by a two-week course of omeprazole, 20 mg daily. Methods: Fasted gastric samples, aspirated using a sterile double-lumen nasogastric tube at the end of the 1 st week (placebo) and the 2nd and 3rd weeks (omeprazole), were cultured aerobically and anaerobically; gastric pH and intra-gastric concentrations of nitrates, nitrites and NOCs were also determined. Results: After weeks 1, 2 and 3, the intra-gastric concentrations of nitrate-reducing bacteria exceeded 10(5) colony-forming units (c.f.u.)/ml in 3, 7 and 9 subjects, respectively (P > 0.05). A gastric pH greater than 4.0 was associated with increased NRB (P < 0.05); however, neither increased gastric pH nor increased NRB, alone or in combination, was associated with increased intra-gastric concentrations of nitrites or NOCs (P > 0.05). Conclusions: A two-week increase in gastric pH in healthy, H. pylori-negative subjects was associated with increased intra-gastric concentrations of nitrate-reducing bacteria but not of nitrites or N-nitroso compounds. These data suggest that reduced gastric acid secretion is not a necessary precursor to the formation of carcinogenic N-nitroso compounds and that other mechanisms should be invoked to explain gastric carcinogenesis.

Letter: Effects of Pro-Inflammatory Cytokines on Acid Secretion

Article

Feb 2000

Ian Leonard Phillip Beales

Helicobacter pylori gastritis: A Th1 mediated disease?

Article

Oct 2000
J BIOTECHNOL

Helicobacter pylori is now considered to be the main cause for most stomach diseases including ulcer, MALT lymphoma, adenocarcinoma and gastritis. The infection with this bacterium is chronic despite a local and systemic immune response towards it. Among the cellular infiltrate that arises during H. pylori-mediated gastritis, there is a considerable frequency of CD4+ Th1 cells producing IFNγ, but not of Th2 cells producing IL-4. Since IFNγ may induce binding of H. pylori to gastric epithelial cells followed by apoptosis of these cells, one may speculate that H. pylori-mediated diseases are in part autoimmune diseases initiated by H. pylori-specific Th1 cells infiltrating the gastric mucosa. Recent support for this hypothesis comes from an animal model in which mice are infected with H. pylori and display strongly reduced gastritis in the absence of IFNγ.

Synergistic interaction between hypergastrinemia and Helicobacter infection in a mouse model of gastric cancer

Article

Jan 2000
GASTROENTEROLOGY

Hypergastrinemia occurs frequently in association with acid suppression and Helicobacter infection, but its role in the progression to gastric atrophy and gastric cancer has not been well defined. The effects of hypergastrinemia, and possible synergy with Helicobacter felis infection, were investigated in insulin-gastrin (INS-GAS) transgenic mice. INS-GAS mice initially showed mild hypergastrinemia, increased maximal gastric acid secretion, and increased parietal cell number but later progressed to decreased parietal cell number and hypochlorhydria. Development of gastric atrophy was associated with increased expression of growth factors, heparin-binding epidermal growth factor and transforming growth factor alpha. At 20 months of age, INS-GAS mice showed no evidence of increased enterochromaffin-like cell number, but instead exhibited gastric metaplasia, dysplasia, carcinoma in situ, and gastric cancer with vascular invasion. Invasive gastric carcinoma was observed in 6 of 8 INS-GAS mice that were >20 months old. Helicobacter felis infection of INS-GAS mice led to accelerated (< or = 8 mo) development of intramucosal carcinoma (85%), with submucosal invasion (54%) and intravascular invasion (46%; P < or = 0.05). These findings support the unexpected conclusion that chronic hypergastrinemia in mice can synergize with Helicobacter infection and contribute to eventual parietal cell loss and progression to gastric cancer.

Hepatic Helicobacter species identified in bile and gallbladder tissue from Chileans with chronic cholecystitis

Article

Apr 1998
GASTROENTEROLOGY

Cancer of the gallbladder is the number one cause of cancer mortality in Chilean women. Incidence rates for this tumor vary widely on a worldwide basis, being approximately 30 times higher in high-risk than in low-risk populations, suggesting that environmental factors such as infectious microorganisms, carcinogens, and nutrition play a role in its pathogenesis. Because several Helicobacter sp. colonize the livers of animals and induce hepatitis, the aim of this study was to determine whether Helicobacter infection was associated with cholecystitis in humans. Bile or resected gallbladder tissue from 46 Chileans with chronic cholecystitis undergoing cholecystectomy were cultured for Helicobacter sp. and subjected to polymerase chain reaction (PCR) analysis using Helicobacter-specific 16S ribosomal RNA primers. Recovery of Helicobacter sp. from frozen specimens was unsuccessful. However, by PCR analysis, 13 of 23 bile samples and 9 of 23 gallbladder tissues were positive for Helicobacter. Eight of the Helicobacter-specific PCR amplicons were sequenced and subjected to phylogenetic analysis. Five sequences represented strains of H. bilis, two strains of "Flexispira rappini" (ATCC 49317), and one strain of H. pullorum. These data support an association of bile-resistant Helicobacter sp. with gallbladder disease. Further studies are needed to ascertain whether similar Helicobacter sp. play a causative role in the development of gallbladder cancer.

Gastro-intestinal microecology of BALB/c nude mice

Article

Aug 1978

The aerobic, facultative, and anaerobic microorganisms cultivable from the stomachs, ilea, ceca, and colons of BALB/c athymic (nu/nu) mice (normal and wasting), thymus-implanted normal nude mice, and their heterozygous (nu/+) littermates were investigated. Ninety-one species representing 23 genera of bacteria and yeasts were isolated from the 27 mice. The wasting nude mice showed significantly lower numbers of lactobacilli in their stomach microbiota than did mice from the other three groups. The littermate animals appeared unique among the four groups in having corynebacteria as a major constituent of their stomach and ileal flora. The normal nude mice appeared to have a more diverse anaerobic stomach flora than their heterozygous littermates. These minor differences are discussed with respect to possible immunological, physiological, and environmental factors as their cause. Because the gastrointestinal microfloras of the mice from the four groups were not radically divergent from each other, it was concluded that loss of T-cell function does not dramatically alter the makeup of the cultivable gastrointestinal microflora in these mice.

Behavior of microflora in the rat stomach: Adhesion of lactobacilli to the keratinized epithelial cells of the rat stomach in vitro

Article

Aug 1975

Certain indigenous bacteria isolated from rats and chickens were found to adhere to keratinized cells obtained from host stomachs and maintained in vitro. Only lactobacilli and staphylococci isolated from rats attached to the keratinized epithelial cells of the rat stomach, suggesting that they are dominant bacteria in the microflora of the stomachs of those animals. Indigenous lactobacilli heated at 60 C for 1 h or treated with the detergents sodium dodecyl sulfate, Tween 80, and Triton X-100 lose the ability to adhere to the keratinized cells of the rat stomach. Indigenous lactobacilli treated with formalin, however, retain the capacity to adhere to the cells. These observations suggest that surface structures of the bacteria are involved in adhesion of indigenous lactobacilli to the keratinized cells of rat stomach.

Possible role of transforming growth factor α in the pathogenesis of Ménétrier's disease: Supportive evidence from humans and transgenic mice

Article

Jan 1993
GASTROENTEROLOGY

Ménétrier's disease is an uncommon disorder of unknown etiology characterized by enlarged gastric folds with foveolar hyperplasia and cystic dilatation of gastric glands. Biochemical features that are seen frequently include hypoproteinemia, hypochlorhydria, and increased gastric mucus. Because transforming growth factor alpha (TGF alpha) is an epithelial cell mitogen that inhibits gastric acid secretion and increases gastric mucin content, we hypothesized that its altered expression might be involved in the pathogenesis of this disease. Therefore, we characterized TGF alpha immunoreactivity in the gastric mucosa of 4 patients with Ménétrier's disease. In contrast to the normal pattern of TGF alpha immunostaining in which TGF alpha appears most concentrated in parietal cells, there was intense staining in the majority of mucous cells in the gastric mucosa of patients with Ménétrier's disease. In one patient from whom sufficient fresh tissue was obtained to isolate RNA, expression of TGF alpha and the epidermal growth factor receptor was higher in the gastric mucosa relative to a normal control. In addition, metallothionein-TGF alpha transgenic mice, which overexpress TGF alpha in gastric mucosa, show a number of features characteristic of Ménétrier's disease. These include foveolar hyperplasia and glandular cystic dilatation, increased gastric neutral mucin staining, and reduced basal and histamine-stimulated rates of acid production. Taken together, observations derived from the human material and correlation with data from a transgenic mouse model support an important role for TGF alpha in the pathogenesis of Ménétrier's disease.

Nomura A, Stemmermann GN, Chyou PH, Kato I, Perez-Perez GI, Blaser MJHelicobacter pylori infection and gastric carcinoma among Japanese Americans in Hawaii. N Engl J Med 325(16): 1132-1136

Article

Nov 1991

Helicobacter pylori are gram-negative spiral bacteria that are associated with chronic gastritis, a known precursor of gastric carcinoma. Persons at high risk for gastric carcinoma have been shown to have a high prevalence of H. pylori infection. We studied the relation of H. pylori infection and gastric carcinoma in a cohort of Japanese American men living in Hawaii. The 5908 men were enrolled and examined from 1967 to 1970. By 1989, 109 cases of pathologically confirmed gastric carcinoma had been identified. The store serum of each patient with gastric carcinoma and of each matched control subject were tested for the presence of serum IgG antibody to H. pylori. Ninety-four percent of the men with gastric carcinoma and 76 percent of the matched control subjects had a positive test for H. pylori antibodies, for an odds ratio of 6.0 (95 percent confidence interval, 2.1 to 17.3). As the level of antibody to H. pylori increased, there was a progressive increase in the risk of gastric carcinoma (P for trend = 0.0009). The association was strong even for men in whom the diagnosis was made 10 or more years after the serum sample was obtained (odds ratio, 10.5; 95 percent confidence interval, 2.5 to 44.8). Infection with H. pylori is strongly associated with an increased risk of gastric carcinoma. However, most persons infected with H. pylori will never have gastric carcinoma. Therefore, other factors that increase the risk of gastric carcinoma among persons infected with H. pylori need to be identified.

Intestinal Barriers to Bacteria and their Toxins

Article

Feb 1990

Immunologic and nonimmunologic processes work together to protect the host from the multitude of microorganisms residing within the intestinal lumen. Mechanical integrity of the intestinal epithelium, mucus in combination with secretory antibody, antimicrobial metabolites of indigenous microorganisms, and peristalsis each limit proliferation and systemic dissemination of enteric pathogens. Uptake of microorganisms by Peyer's patches and other intestinal lymphoid structures and translocation circumvent the mucosal barrier, especially in immunosuppressed individuals. Improved understanding of the composition and limitation of the intestinal barrier, coupled with advances in genetic engineering of immunogenic bacteria, development of oral delivery systems, and immunomodulators, now make enhancement of mucosal barriers feasible.

Genetic etiology of gastric carcinoma: II. Segregation analysis of gastric pH, nitrate, and nitrite

Article

Jan 1987

A study of gastric pH, nitrate, and nitrite in 110 families collected as part of a cohort from the Narino region of Colombia is presented. All three traits are familial and have a significant linearly increasing age trend. Gastric pH has a clear bimodal distribution but does not show Mendelian segregation. The nitrate distribution is slightly skewed, but generational heterogeneity explains the data best. Gastric nitrite is also biomodal with a clear break at concentration 1.08 micrograms/ml, and 74% of the observations at zero concentration; it shows a recessive Mendelian segregation with significant residual spouse correlation. This model also fits the data best when nitrite is dichotomized into detected (measurable) and undetected values. The estimated frequency of the recessive allele is .57, so that an estimated 32% of the population sampled are recessives. Recessives whose spouses have measurable nitrite have an estimated penetrance of 99.3% at age 30 years, whereas those whose spouses have zero or undetected nitrite have a penetrance of only 8.8% at age 30 years. It appears that gastric nitrite, and, from our previous study of these families, chronic atrophic gastritis are important biologic markers for the early identification of persons predisposed to gastric cancer.

Effects of vitamins C and E on N-nitroso compound formation, carcinogenesis, and cancer

Article

Nov 1986

Sidney S. Mirvish

The properties of N-nitroso compounds (NNC) and of vitamins C and E are briefly described. The author reviews the ability of vitamins C and E to inhibit NNC formation in chemical systems, in nitrite-preserved meat, in experimental animals and in humans. Dietary vitamins C and E both produced 30% to 60% inhibitions in most carcinogenesis experiments employing preformed carcinogens. Vitamin C reversed transformation in an in vitro system. Carcinogenicity tests of the vitamins are reviewed (vitamin C can promote bladder carcinogenesis). Intake of fresh fruits and vegetables (which contain vitamin C) is negatively correlated with cancer of the stomach, esophagus, larynx, mouth and cervix. For gastric and esophageal cancer, there is evidence that this association is due to an inhibition of in vivo NNC formation. Vitamin C is apparently not a useful treatment for cancer. The author supports the recommendation that fresh fruit and vegetable intake be increased to lower the risk of cancer.

Differentiation of Immature Mucous Cells into Parietal, Argyrophil, and Chief Cells in Stomach Grafts

Article

Aug 1970

Microscopic and submicroscopic studies on regenerating gastric mucosa neonatally grafted in the subcutaneous tissue of littermate mice have revealed that immature mucous cells are totipotent; ultimately they transform into mature mucous, parietal, argyrophil, and chief cells in the gastric glands.

Unidentified Curved Bacilli in the Stomach of Patients with Gastritis and Peptic Ulceration.

Article

Jul 1984

Biopsy specimens were taken from intact areas of antral mucosa in 100 consecutive consenting patients presenting for gastroscopy. Spiral or curved bacilli were demonstrated in specimens from 58 patients. Bacilli cultured from 11 of these biopsies were gram-negative, flagellate, and microaerophilic and appeared to be a new species related to the genus Campylobacter. The bacteria were present in almost all patients with active chronic gastritis, duodenal ulcer, or gastric ulcer and thus may be an important factor in the aetiology of these diseases.

Intragastric bacterial activity and nitrosation before, during, and after treatment with omeprazole

Article

Oct 1984

Ten healthy volunteers were studied before, during, and after treatment with omeprazole 30 mg daily for two weeks. On the 14th night mean nocturnal (2100-0700) intragastric acidity was significantly decreased by 75% (p less than 0.001). At 0700, 22 hours after the last dose of omeprazole, there were significant increases in the bacterial count and the nitrite and N-nitrosamine concentrations in the gastric juice (p less than 0.001). Three days later these changes had resolved. Short term treatment of healthy volunteers with omeprazole is associated with a short lived increase in the gastric bacterial flora, with endogenous production of N-nitroso compounds.

Pernicious Anaemia, Intragastric Bacterial Overgrowth, and Possible Consequences

Article

Jun 1984

Intragastric bacterial colonization is well known in pernicious anaemia (PA), but its consequences have rarely been investigated. We have studied the clinical history, blood samples, and endoscopic biopsies from the stomach and duodenum of 80 patients with PA. In a random subgroup of 22 patients gastric juice was collected for aerobic culture and for estimation of nitrate, nitrate-reducing bacteria, nitrite, and N-nitrosamines; duodenal juice was studied in parallel in eight of these subjects. Gastric and duodenal juice had high bacterial counts; faecal organisms were found in 14 patients. The mean count of nitrate-reducing bacteria was significantly higher than in a control group of patients with peptic ulcer disease (p less than 0.001), as was the nitrite concentration (p less than 0.001). Thirty-three of the 80 patients had gastric dysplasias; 1 early gastric carcinoma was also found. Duodenitis was present in 39 out of 80 cases, in 6 associated with partial villous atrophy. A history of malabsorption and/or chronic intermittent diarrhoea was obtained significantly more often from patients with duodenitis. Four patients developed acute gastroenteritis shortly before or during the time of the study, two having a salmonella infection. Bacterial overgrowth in PA may be facilitated by altered immunological conditions, since low serum levels of IgA and IgG were found in this patient group.

Cytotoxic T cells in small intestine epithelial, lamina propria and lung lymphocytes

Article

Nov 1981

We have examined the development of specific cytotoxic T-cell activity in the lungs and the epithelium and lamina propria of the small intestine following tumour cell inoculation by subcutaneous or intraperitoneal routes. After an intraperitoneal injection of tumour cells, large amounts of cytotoxic activity are detectable in the lungs and lamina propria. In comparison, the epithelial lymphocytes of the small intestine display low cytotoxic activity. After a subcutaneous injection, little cytotoxicity is detectable except in the lungs and the development of such cytotoxicity has a much shorter time course compared with that induced by an intraperitoneal inoculation of tumour cells. The data indicate a marked difference in the functional capacity of lymphocytes from the epithelium and lamina propria of the small intestine.

Role of N-nitroso compounds (NOC) and N-nitrosation in etiology of gastric, esophageal, nasopharyngeal and bladder cancer and contribution to cancer of known exposures to NOC

Article

Jul 1995
CANCER LETT

Sidney S. Mirvish

The questions of whether and how N-nitroso compounds (NOC) may be inducing cancer in humans are discussed. The principal subjects covered include nitrite-derived alkylating agents that are not NOC, reasons for the wide tissue specificity of carcinogenesis by NOC, the acute toxicity of nitrosamines in humans, mechanisms of in vivo formation of NOC by chemical and bacterial nitrosation in the stomach and via nitric oxide (NO) formation during inflammation, studies on nitrite esters, use of the nitrosoproline test to follow human gastric nitrosation, correlations of nitrate in food and water with in vivo nitrosation and the inhibition of gastric nitrosation by vitamin C and polyphenols. Evidence that specific cancers are caused by NOC is reviewed for cancer of the stomach, esophagus, nasopharynx, urinary bladder in bilharzia and colon. I review the occurrence of nitrosamines in tobacco products, nitrite-cured meat (which might be linked with childhood leukemia and brain cancer) and other foods, and in drugs and industrial situations. Finally, I discuss clues from mutations in ras and p53 genes in human tumors about whether NOC are etiologic agents and draw some general conclusions.

Expression of antral gastrin and somatostatin mRNA in Helicobacter pylori- infected subjects

Article

Oct 1994

We investigated the gene expression of antral gastrin and somatostatin in Helicobacter pylori-infected subjects. Twelve asymptomatic men with normal endoscopic findings participated in this study, four of whom were infected with H. pylori. Biopsy specimens of the gastric mucosa were obtained after subjects had fasted overnight. Serum gastrin levels, antral gastrin and somatostatin content, and antral G- and D-cell densities also were measured. Fasting serum gastrin levels were significantly higher in H. pylori-positive subjects than in H. pylori-negative subjects. There were no differences between groups in antral gastrin content, G-cell density, or gastrin mRNA levels. Antral somatostatin content, D-cell density, somatostatin mRNA levels, and the somatostatin mRNA:D-cell density ratio were significantly decreased in H. pylori-positive subjects. Our results suggest that in addition to reduced antral D-cell density, a suppression of somatostatin synthesis in D-cells may have contributed to the decrease in antral somatostatin in H. pylori-infected subjects.

Inhibiting gastric H(+)-K(+)-ATPase activity by omeprazole promotes degeneration and production of parietal cells

Article

May 1994
Am J Physiol

Parietal cell morphology was studied after chronic inhibition of gastric H(+)-K(+)-adenosinetriphosphatase (ATPase) by omeprazole. Gastric mucosa from rabbits treated with omeprazole every 12 h (1 mg/kg sc) for 5 days were compared with sham-injected animals using immunohistochemistry and electron microscopy. Three immunocytochemical markers, including antibodies against the alpha- and beta-subunits of the H(+)-K(+)-ATPase, showed that some parietal cells in omeprazole-treated rabbits displayed light areas and granularity in their cytoplasm. These abnormalities were also apparent in semithin sections. Electron microscopy was used to categorize and quantitate the specific structural abnormalities in parietal cells. Cells were classified as normal, altered, or degenerated. For control tissues, altered and degenerated parietal cells were few; they collectively represented 6% of total parietal cells and were located mainly deep in the gland base. For omeprazole-treated tissues, altered and degenerated parietal cells occurred throughout the gland and averaged 62% of total parietal cells. In addition, macrophages invaded the mucosa presumably to eliminate degenerated cells. Although there was an increase in parietal cell degeneration, enhanced parietal cell generation was suggested by increases in mitosis among proliferative cells and, more specifically, in the number of preparietal cells. After 3 days of recovery from the omeprazole regimen, parietal cells and the gastric mucosa appeared to recover the normal morphology. In conclusion, blocking H(+)-K(+)-ATPase by omeprazole enhances degeneration and macrophage-mediated elimination of parietal cells and also causes an increase in preparietal cell production. Thus omeprazole temporarily changes the dynamic features of parietal cells in the rabbit to make them die early and grow fast.

N-Nitroso compounds in fresh gastric juice and their relation to intragastric pH and nitrite employing an improved analytical method

Article

Dec 1993

In order to examine further the relationship between intragastric N-nitrosation, gastric pH and nitrite, 457 fresh, fasting gastric juice samples were analysed for total N-nitroso compounds (NOC) and nitrite concentrations using a recently described improved assay method. Nitrite in log values was linearly related to intragastric pH (r = 0.887, P < 0.01) with a regression equation log[nitrite] (mumol/l) = 0.489 x pH - 2.209. Significantly higher NOC concentrations were found at intragastric pH ranges of 1.13-2.99 (mean +/- SE: 1.45 +/- 0.17 mumol/l, P < 0.05) and 6.00-8.42 (3.57 +/- 0.33 mumol/l, P < 0.01) compared with that at pH 3.00-5.99 (1.02 +/- 0.12 mumol/l). NOC concentration was significantly related to log nitrite concentration at both the low pH range 1.13-4.99 (r = 0.169, P < 0.01) and the high pH range 5.00-8.42 (r = 0.450, P < 0.01). The results in the present study confirm that both acid-catalysed N-nitrosation and biologically-catalysed N-nitrosation occur in the human stomach. However, great variations in nitrite and NOC concentrations were observed in both low and high pH samples, indicating that, as expected, both the acid-catalysed N-nitrosation and biologically-catalysed N-nitrosation processes are markedly affected by factors other than intragastric pH and nitrite.

Dynamics of epithelial cells in the corpus of the mouse stomach. I. Identification of proliferative cell types and pinpointing of the stem cell

Article

Jun 1993

In a recent study of the corpus epithelium in the mouse stomach, eleven cell types have been identified and enumerated (Karam and Leblond: Anat. Rec. 232:231–246, 1992). The dynamics of these cells will be examined in a series of five articles, of which this is the first. This article focuses on the proliferative ability of the cells, as measured by the labeling index in radioautographs from mice sacrificed 30 min after an intravenous injection of ³ H‐thymidine. Furthermore, the ultrastructure of the cells found to be proliferative was examined in the hope of finding features characteristic of stem cells. On the basis of their labeling index, the epithelial cells have been classified into four groups. The first includes three cell types which do not take up any label and accordingly are non‐dividing: parietal or oxyntic cells, cells named pre‐parietal as they are immature cells suspected of being parietal cell precursors, and the rare caveolated or brush cells. The second group is composed of three cell types which are only rarely labeled and, therefore, divide only occasionally: zymogenic or chief cells, entero‐endocrine cells, and cells named pre‐zymogenic cells as they are suspected of being zymogenic cell precursors. The third group includes two cell types which are always labeled at a low degree and, therefore, divide regularly, but at a low rate: surface mucous cells, herein called pit cells, whose labeling index is 0.8%, and mucous neck cells, simply known as neck cells, 1.8%. The final group consists of three immature cell types with high labeling indices indicating a high rate of division: granule‐free cells, which are devoid of secretory granules and have the highest labeling index, 32.4%, prepit cells, which possess a few dense secretory granules similar to, but smaller than, those in pit cells, 24.6%, and pre‐neck cells, with a small number of secretory granules similar to, but smaller than, those in neck cells, 11.3%. These three cell types, as well as pre‐parietal cells, are rapidly renewed, with the turnover times estimated at 3.0 days for pre‐neck and pre‐parietal cells and less than 2.6 days for granule‐free and pre‐pit cells. Ultrastructural studies of granule‐free cells reveal that they may be sub‐divided into three subtypes according to their Golgi features: subtype I, which consists of undifferentiated cells in which the Golgi trans face exhibits no prosecretory vesicles; subtype II, named pre‐pit cell precursors because the Golgi trans face shows prosecretory vesicles similar to those in pre‐pit cells; and subtype III, named pre‐neck cell precursors , whose prosecretory vesicles are similar to those in pre‐neck cells. On the other hand, pre‐parietal cells include three variants that could each arise from a different granule‐free subtype: variant I, which has no mucous secretory granules, could arise from the undifferentiated cells; variant II, which possesses dense mucous granules similar to those in pre‐pit cells, could come from pre‐pit cell precursors; and variant III, which has cored granules as in pre‐neck cells, could come from pre‐neck cell precursors. Only the undifferentiated granule‐free cells have the features expected from stem cells and, therefore, are considered to be the stem cells of the epithelium. A model based on the radioautographic and morphological data (Fig. 17) summarises the filiation of the other immature cell types as follows. The undifferentiated granule‐free cells as stem cells reproduce themselves and give rise to three other cell types: (1) the pre‐parietal cells lacking secretory granules (i.e., variant I); (2) the pre‐pit cell precursors, which mainly give rise to pre‐pit cells, but also yield the variant II pre‐parietal cells; (3) the pre‐neck cell precursors, which mainly give rise to pre‐neck cells, but also yield the variant III pre‐parietal cells. Further differentiation of these immature cell types into the other cells of the corpus epithelium is examined in the succeeding articles. © 1993 Wiley‐Liss, Inc.

A Novel Method for Isolating Mononuclear Cells from the Stomachs of Mice with Experimental Autoimmune Gastritis

Article

Feb 1995

Autoimmune gastritis induced in BALB/c mice by neonatal thymectomy is a CD4+ T cell-mediated disease. The disease is characterised by mononuclear cell infiltrates in the gastric mucosa, loss of gastric parietal and chief cells and autoantibodies to the gastric H/K ATPase. Here we describe a simple non-enzymatic method for isolating cellular infiltrates from stomachs of gastric mice by injection of medium directly into stomach walls, causing swelling and rupture. Using this method, large numbers of viable lymphocytes were released from stomachs for analysis by flow cytometry. An 8.3 fold increase in the total number of lymphocytes from diseased stomachs compared to normal controls was observed. Total cell numbers of CD4+ and B cells were increased 4.8 fold and 39.5 fold respectively, in diseased stomachs compared with controls. No change was observed in the CD8+ T cell population. This method will allow detailed quantitative analysis of cellular infiltrates during the development of the gastric lesion and enrichment of pathogenic T cells for analysis and cloning. This procedure may have general application for the isolation of cellular infiltrates from lesion sites of other organs.

Fos is required for EGF stimulation of the gastrin promoter

Article

Jan 1997
Am J Physiol

Gastrin gene expression is regulated by developmental cues, pH, and inflammation. These processes are mediated by various extracellular ligands, e.g., growth factors, cytokines, and neuropeptides that also stimulate c-fos gene expression. Therefore, to determine whether Fos is required for stimulation of the gastrin promoter, a c-fos sense expression vector was coexpressed with a gastrin reporter construct in a GH4 rat pituitary cell line. We found that epidermal growth factor (EGF) and tumor necrosis factor-alpha (TNF-alpha) transiently stimulate an increase in Fos protein that precedes stimulation of the gastrin promoter. However, the induction mediated by TNF-alpha was weaker than that mediated by EGF, indicating minimal overlap of the signaling pathways activated by EGF and TNF-alpha. Accordingly, overexpression of c-fos mRNA facilitated primarily EGF rather than TNF-alpha induction of the gastrin promoter. Expression of the c-fos gene in the absence of ligand did not stimulate the gastrin promoter. Thus c-fos gene expression is required but is not sufficient for induction of the gastrin promoter by EGF.

A Standardized Mouse Model of Helicobacter pylori infection: Introducing the Sydney strain

Article

May 1997
GASTROENTEROLOGY

Currently available Helicobacter pylori models show variable and, in some instances, poor colonization. There is a need for a strain with high colonizing ability to act as a standard for animal studies. After screening a range of fresh clinical isolates and long-term adaptation in mice, a strain of H. pylon has been isolated with a very good colonizing ability. This strain, named the Sydney strain of H. pylori (strain SS1), is cagA and vacA positive. High levels of colonization (10(6)-10(7) colony-forming units/g tissue) were achieved consistently in C57BL/6 mice. Colonization levels varied depending on the mouse strain used with BALB/c, DBA/2, and C3H/He, all being colonized but in lower numbers. In all strains of mice, bacteria were clearly visible at the junctional zone between the antrum and the body. The phenotype was stable with colonizing ability remaining after 20 subcultures in vitro. The bacterium attached firmly to gastric epithelium. During 8 months, a chronic active gastritis slowly developed, progressing to severe atrophy in both C57BL/6 and BALB/c mice. The Sydney strain of H. pylori is available to all and will provide a standardized mouse model for vaccine development, compound screening, and studies in pathogenesis.

Gastrin deficiency results in altered gastric differentiation and decreased colonic proliferation in mice

Article

Sep 1997
GASTROENTEROLOGY

Gastrin is a peptide hormone important in the regulation of both acid secretion and differentiation of oxyntic mucosal cells of the stomach. To further elucidate the role of gastrin in the growth and development of the gastrointestinal tract, we have generated mice that are deficient in gastrin. Gastrin-deficient mice were generated through targeted gene disruption. Gastric and colonic architecture were determined by routine histology and immunohistochemical techniques. Proliferation was assessed by 5-bromo-2'-deoxyuridine incorporation. Targeted disruption of the gastrin gene resulted in mice incapable of expressing gastrin messenger RNA (mRNA) or producing gastrin peptide. This deficiency led to a marked change in gastric architecture, with a decrease in number of parietal and enterochromaffin-like cells and an increase in number of mucous neck cells. There was no difference in the proliferation labeling index of the stomach in gastrin-deficient mice (3.04% +/- 0.33%) compared with wild-type littermates (3.15% +/- 0.18%). The colon of gastrin-deficient mice seemed normal histologically, although there was a decreased proliferation labeling index (2.97% +/- 0.52%) compared with wild-type littermates (4.71% +/- 0.44%; P < 0.01). Gastrin is important in regulating the differentiation of the gastric mucosa and is a trophic factor for the colonic mucosa.

Helicobacter pylori and non-Helicobacter pylori bacterial flora in gastric mucosal and tumour specimens of patients with primary gastric lymphoma

Article

Dec 1997

There is an association between Helicobacter pylori (H. pylori) and gastric mucosa-associated lymphoid tissue (MALT) and MALT lymphoma. Histologically, mainly non-specific stains are used to detect H. pylori, such as haematoxylin-eosin (HE) or modified Giemsa (MG). In this study, both a MG and a specific immunohistochemical stain (IMM) for H. pylori (Dako B471) were performed on sequential slides of resected material containing tumour and non-tumorous gastric mucosa from patients with primary gastric lymphoma (n = 52). Special attention was paid to the presence of non-H. pylori bacterial flora diagnosed by a positive MG (according to form and localization) and a subsequently negative IMM. On all slides, bacterial density was scored semiquantitatively (grades 0, 1, 2, 3). In total, 32 (61.5%) patients were H. pylori positive using IMM and 34 (65.4%) were non-H. pylori positive using MG. In 24 out of the 34 patients, the non-H. pylori flora consisted mainly of cocci in combination with rods in 15 patients, mostly in minor quantities; in another 10 patients, high numbers of both cocci and different types of rods were present. Most non-H. pylori bacteria were localized superficially, although in 22 patients minor quantities of non-H. pylori were also seen in the glandular lumina. After all of the patients had been analysed, no differences in the density of H. pylori and of non-H. pylori flora were found. Only when comparing patients who had a small-cell lymphoma with those who had a large-cell lymphoma was a significantly higher density of H. pylori found in the corpus mucosa of large-cell lymphomas and a higher prevalence of non-H. pylori was found in tumours, in antrum or corpus, of patients with large-cell lymphomas. In conclusion, with joint evaluation using MG and a H. pylori-specific immunohistochemical stains, the proportion of H. pylori-positive gastric lymphoma patients was lower than in most previous studies but other bacteria were found in a relatively high proportion. The role of the non-H. pylori intragastric bacterial flora identified in this study has to be further elucidated in the aetiopathogenesis of primary gastric lymphoma.

Effect of Cytokines on Acid Secretion and Gastrin Secretion in Helicobacter pylori Infection and Aspirin-Induced Gastritis

Article

Dec 1998

Ian Leonard Phillip Beales

Gastrin induces heparin-binding epidermal growth factor-like growth factor in rat gastric epithelial cells transfected with gastrin receptor

Article

Jan 1999
GASTROENTEROLOGY

Parietal cells express heparin-binding epidermal growth factor (EGF)-like growth factor (HB-EGF). However, it is unknown whether HB-EGF mediates the trophic action of gastrin. The purpose of this study was to determine whether gastrin modulates the expression of HB-EGF, which mediates the proliferative effects of gastrin on gastric epithelial cells. RGM1 cells, a rat gastric epithelial cell line, were transfected with a human gastrin receptor complementary DNA. Gastrin induction of messenger RNAs (mRNAs) for EGF-related polypeptides was assayed by Northern blotting. Processing of cell surface-associated proHB-EGF and secretion of HB-EGF were determined by flow cytometry and Western blotting, respectively. Tyrosine phosphorylation of the EGF receptor was assayed by immunoprecipitation and Western blotting with an antiphosphotyrosine antibody. Cell growth was evaluated by [3H]thymidine incorporation. Gastrin induced expression of HB-EGF mRNA, processing of proHB-EGF, release of HB-EGF into the medium, and tyrosine phosphorylation of the EGF receptor. The growth-stimulatory effects of gastrin were partly inhibited by anti-rat HB-EGF serum and completely blocked by AG1478, an EGF receptor-specific tyrphostin. The findings suggest that HB-EGF at least partially mediates the proliferative effects of gastrin on gastric epithelial cells.

Omeprazole and dietary nitrate independently affect levels of Vitamin C and nitrite in gastric juice

Article

May 1999
GASTROENTEROLOGY

Hypochlorhydria is associated with an increased risk of gastric cancer. We have studied the effect of pharmacologically induced hypochlorhydria on the gastric juice ascorbate/nitrite ratio, which regulates the synthesis of potentially carcinogenic N-nitroso compounds. Saliva, gastric juice, and serum from 20 healthy volunteers (9 positive for Helicobacter pylori), with a mean age of 30 years (range, 20-47 years), were analyzed for nitrite, ascorbic acid, and total vitamin C before and for 2 hours after ingestion of 2 mmol [corrected] nitrate (nitrate content of a standard salad meal). This was repeated after 4 weeks of treatment with omeprazole, 40 mg daily. Before omeprazole treatment, the nitrate meal lowered gastric ascorbic acid levels from 3.8 to 0.9 microg/mL (P < 0.05) and increased median salivary nitrite levels from 44 to 262 micromol/L (P < 0.001); gastric nitrite concentration remained undetected in 10 subjects. Omeprazole increased median fasting gastric nitrite levels from 0 to 13 micromol/L (P = 0.001) and decreased fasting gastric ascorbic acid levels from 3.8 to 0.7 microg/mL (P < 0.001). With omeprazole treatment, gastric nitrite levels after the nitrate meal were markedly increased at 154 micromol/L (range, 49-384 micromol/L; P < 0.001). In H. pylori-infected subjects, omeprazole also decreased total vitamin C levels in both gastric juice and serum. Omeprazole and dietary nitrate independently decrease the ascorbate/nitrite ratio. This may lead to an increased risk of gastric cancer.

Differential features of gastric cancer patients, either Helicobacter pylori positive or Helicobacter pylori negative

Article

Dec 1999
Ital J Gastroenterol Hepatol

Helicobacter pylori infection is associated with an increased risk of gastric cancer. In Helicobacter pylori negative patients, factors different from those in Helicobacter pylori positive patients may be involved in gastric carcinogenesis. Thirty-nine recently diagnosed consecutive patients with gastric cancer were investigated. Gastric biopsies were obtained for detection of Helicobacter pylori (by immunohistochemistry), non-Helicobacter pylori flora (by modified Giemsa and culture) and histological assessment according to the Sydney classification by Haematoxylin-Eosin staining. In serum samples, Helicobacter pylori antibodies were determined by IgG enzyme-linked immunosorbent assay, IgA enzyme-linked immunosorbent assay, and Western blotting. Furthermore, serum gastrin, pepsinogen A and C and plasma chromogranin A were determined. Helicobacter pylori was detected by immunohistochemistry in 53.8%, by IgG in 56.4%, by IgA in 33.3%, and by Western blotting in 74.4% of the 39 patients. Ten patients (25.6%) were negative by both histology and serology. Non-Helicobacter pylori flora was detected in 27 of the 39 patients (69.2%) with a similar frequency in Helicobacter pylori positive and negative patients. Helicobacter pylori positivity was found significantly more often in diffuse than intestinal type carcinoma patients (p < 0.05). Elevated gastrin levels and antrum-sparing atrophic gastritis were more frequent in Helicobacter pylori negative than in Helicobacter pylori positive patients (p < 0.05). In 10 out of 39 gastric cancer patients, no evidence of previous or current Helicobacter pylori infection could be demonstrated. Non-Helicobacter pylori was found in 69.2% of patients regardless of the Helicobacter pylori status. Further studies are needed to establish the contribution of non-Helicobacter pylori flora as well as antrum-sparing atrophic gastritis with hypergastrinaemia to the development of gastric cancer.

Effects of pro-inflammatory cytokines on acid secretion

Article

Mar 2000

Ian Leonard Phillip Beales

Helicobacter pylori is the primary cause of gastric cancer

Article

Feb 2000

DY Graham

Helicobacter pylori causes gastric cancer in human and in experimental animals. The link between gastritis and H. pylori is causal. Differences in the incidence of gastric cancer in populations with similar high prevalence of H. pylori infection can be related to the differences in the age of acquisition of chronic atrophic gastritis, which in turn is related to an interaction between environmental factors, especially diet, and H. pylori infection. The low odds ratios reported in epidemiology studies evaluating the relation between gastric cancer and H. pylori infection reflect the high overall prevalence of H. pylori in the population and do not accurately reflect the strength of the association. It is time to stop doing serologic studies to confirm the association of gastric cancer with H. pylori and instead expend our efforts on eliminating the infection and investigating the mechanism(s) and interactions.

Epidemiology of gastric cancer: An evaluation of available evidence

Article

Feb 2000

D Palli

Despite a dramatic reduction in incidence and mortality rates, gastric cancer (GC) is still one of the most common malignant neoplasias worldwide. Surgical and medical treatments have not substantially improved during the last decades, and large-scale early diagnosis programs have proven feasible in only one high-risk country, Japan. A large number of studies have indicated that salted, smoked, pickled, and preserved foods (rich in salt, nitrite, and preformed N-nitroso compounds) are associated with an increased risk of GC. In contrast, strong evidence has been provided that high consumption of fresh fruit and raw vegetables and a high intake of antioxidants are associated with a reduced risk of GC. Domestic refrigeration and reduced salt consumption are considered to play a role in explaining the decreasing temporal trend and the geographical patterns of GC. Familial factors have been suspected to play a role in GC susceptibility, and recently germ line mutations in the E-cadherin gene were identified in a few families. Evidence of a positive association between Helicobacter pylori infection and GC risk has been provided by most prospective studies that overall suggest a two- to threefold increase in risk. Randomized intervention studies on H. pylori eradication and its effects on GC predisposing conditions (atrophic gastritis and intestinal metaplasia) are in progress and represent a priority for epidemiological research in view of the potential preventive applications. Overall, it is evident that several factors (including diet, individual susceptibility and H. pylori infection) interact in a complex multifactorial process, leading over a long period of time to GC.

Zavros Y, Rieder G, Ferguson A, Samuelson LC, Merchant JL.. Genetic or chemical hypochlorhydria is associated with inflammation that modulates parietal and G-cell populations in mice. Gastroenterology 122: 119-133

Abstract

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