Helicobacter pylori infection induces gastric cancer in mongolian gerbils

Significant Association of Streptococcus bovis with Malignant Gastrointestinal Diseases

Streptococcus bovis is a Gram-positive bacterium causing serious human infections, including endocarditis and bacteremia, and is usually associated with underlying disease. The aims of the current study were to compare prevalence of the bacterium associated with malignant and nonmalignant gastrointestinal diseases and to determine the susceptibility of the isolated strains to different antimicrobial agents. The result showed that the prevalence of S. bovis in stool specimens from patients with malignant or with nonmalignant gastrointestinal diseases was statistically significant. This result may support the idea that there is correlation between S. bovis and the malignant gastrointestinal diseases.

Murine models of H. pylori-induced gastritis and gastric adenocarcinoma

Laboratory mice have become one of the best animal species for mechanistic studies in gastrointestinal research. Their abundant genetic information, the way of causing carcinogenesis easily by transgenic and gene knockout techniques, limited effort in time and costs, and their practicability provide advantages over other animal models. Meanwhile, several murine practical models have been established for the investigation of the initiation, expansion, and progression of gastritis and gastric carcinoma, for assessing the effects of bacterial, genetic and environmental factors, and for evaluating therapeutic and preventive strategies in gastric diseases. This article gives a review of murine models of gastritis and gastric cancer, placing emphasis on the models associated with Helicobacter pylori infection and techniques used in our laboratory. We discuss matters of murine gastric anatomy, as well as techniques of infection, tissue preparation, and histology.

Expression of angiotensin II type 1 and type 2 receptor mRNAs in the gastric mucosa of Helicobacter pylori-infected Mongolian gerbils

BACKGROUND

The renin-angiotensin system (RAS) plays an important role in normal homeostasis, carcinogenesis-related angiogenesis, and cell proliferation. Helicobacter pylori infection causes infiltration of inflammatory cells into the gastric mucosa and is considered the major cause of gastric cancer. Whether RAS plays a role in H. pylori infection-related gastric diseases remains unclear. We investigated the changes in gastric mucosal angiotensin II type 1 receptor (AT1R) and type 2 receptor (AT2R) mRNA levels throughout the time course of H. pylori infection in Mongolian gerbils.

METHODS

Mongolian gerbils were infected with wild-type H. pylori (for 12 months) or with its isogenic oipA mutant (for 3 months). Gastric mucosal AT1R and AT2R mRNA levels were assessed using real-time reverse transcription-polymerase chain reaction.

RESULTS

The gastric mucosal AT1R mRNA level was significantly associated with the severity of inflammatory cell infiltration into the gastric mucosa that reached maximal levels at 12 months after infection in both the antrum and body. Inflammatory cell infiltration scores and AT1R and AT2R mRNA levels were significantly lower in oipA mutant than wild-type infections. Mucosal AT1R and AT2R mRNA expressions in wild-type H. pylori-infected gerbils with gastric ulcers were significantly higher than in those without ulcers (P < 0.01).

CONCLUSIONS

Gastric mucosal ATR expression gradually increases during the course of H. pylori infection. Up-regulation of the RAS in association with progressive gastric inflammation suggests a potential role of the RAS in gastric carcinogenesis. OipA appears to play a role in AT1R and AT2R expression and the resulting inflammation.

Paxillin is a novel cellular target for converging Helicobacter pylori-induced cellular signaling

Paxillin is involved in the regulation of Helicobacter pylori-mediated gastric epithelial cell motility. We investigated the signaling pathways regulating H. pylori-induced paxillin phosphorylation and the effect of the H. pylori virulence factors cag pathogenicity island (PAI) and outer inflammatory protein (OipA) on actin stress fiber formation, cell phenotype, and IL-8 production. Gastric cell infection with live H. pylori induced site-specific phosphorylation of paxillin tyrosine (Y) 31 and Y118 in a time- and concentration-dependent manner. Activated paxillin localized in the cytoplasm at the tips of H. pylori-induced actin stress fibers. Isogenic oipA mutants significantly reduced paxillin phosphorylation at Y31 and Y118 and reduced actin stress fiber formation. In contrast, cag PAI mutants only inhibited paxillin Y118 phosphorylation. Silencing of epidermal growth factor receptor (EGFR), focal adhesion kinase (FAK), or protein kinase B (Akt) expression by small-interfering RNAs or inhibiting kinase activity of EGFR, Src, or phosphatidylinositol 3-kinase (PI3K) markedly reduced H. pylori-induced paxillin phosphorylation and morphologic alterations. Reduced FAK expression or lack of Src kinase activity suppressed H. pylori-induced IL-8 production. Compared with infection with the wild type, infection with the cag PAI mutant and oipA mutant reduced IL-8 production by nearly 80 and 50%. OipA-induced IL-8 production was FAK- and Src-dependent, although a FAK/Src-independent pathway for IL-8 production also exists, and the cag PAI may be mainly involved in this pathway. We propose paxillin as a novel cellular target for converging H. pylori-induced EGFR, FAK/Src, and PI3K/Akt signaling to regulate cytoskeletal reorganization and IL-8 production in part, thus contributing to the H. pylori-induced diseases.

Animal models of gastric cancer

Gastric cancer is the second most common cause of cancer-related mortality (9.7% of the total) worldwide. Gastric carcinogenesis is a multiple-step process that involves multiple factors, such as bacteria, immune response and host factors. Animal models play a crucial role in the research of the biological behavior, diagnosis and treatment of gastric cancer. In this article we will review current advances in the development of animal models of gastric cancer in terms of microorganism-induced models, chemical carcinogen-induced models, tumor cell implantation, genetically modified models and in silico models.

The origin of pre-neoplastic metaplasia in the stomach: chief cells emerge from the Mist

The digestive-enzyme secreting, gastric epithelial chief (zymogenic) cell is remarkable and underappreciated. Here, we discuss how all available evidence suggests that mature chief cells in the adult, mammalian stomach are postmitotic, slowly turning over cells that arise via a relatively long-lived progenitor, the mucous neck cell, The differentiation of chief cells from neck cells does not involve cell division, and the neck cell has its own distinct pattern of gene expression and putative physiological function. Thus, the ontogeny of the normal chief cell lineage exemplifies transdifferentiation. Furthermore, under pathophysiogical loss of acid-secreting parietal cell, the chief cell lineage can itself trasndifferentiate into a mucous cell metaplasia designated Spasmolytic Polypeptide Expressing Metaplasia (SPEM). Especially in the presence of inflammation, this metaplastic lineage can regain proliferative capacity and, in humans may also further differentiate into intestinal metaplasia. The results indicate that gastric fundic lineages display remarkable plasticity in both physiological ontogeny and pathophysiological pre-neoplastic metaplasia.

Gastric diseases in Mongolian gerbils infected with different strains of Helicobacter pylori

Helicobacter pylori (H.pylori) is a bacterium responsible for one of the most widespread infections found in humans. It colonizes the gastric mucosa and can result in chronic gastritis and gastric cancer. The incidence of spontaneous gastric gastritis is low in Mongolian gerbils, and spontaneous H.pylori infection can not be detected in this animal. Since H.pylori-related gastric diseases in Mongolian gerbils are very similar to those in humans, they have been considered as ideal animals to establish H.pylori infection models. However, different strains of H.pylori may induce different types of pathologic changes in Mongolian gerbils. Clarification of the pathogenic mechanisms of different strains of H.pylori may provide a theoretical basis for screening appropriate H.pylori strains and directing individualized treatment in patients with H.pylori-related gastric diseases. In this paper, we review the recent progress in research of gastric diseases in Mongolian gerbils infected with different strains of H.pylori.

Gastric carcinogenesis

INTRODUCTION

In most patients, gastric cancer is diagnosed in advanced stage. Curative treatment options are limited and the mortality is high. The process of gastric carcinogenesis is triggered by Helicobacter pylori-driven gastritis and is further characterized by its complexity of interaction with other risk factors. Health care systems are challenged for the improvement of prevention, early diagnosis, and effective treatments.

METHODS

An extensive literature research has been performed to elucidate the interplay between etiological factors involved in gastric carcinogenesis.

RESULTS

H. pylori is the most important carcinogen for gastric adenocarcinoma. Evidence is provided by experiments including animal studies as well as clinical observational and interventional studies in humans. Eradication has the potential to prevent gastric cancer and offers the greatest benefit if performed before premalignant changes of the gastric mucosa have occurred. Bacterial virulence factors are essential players in modulating the immune response involved in the initiation of the carcinogenesis in the stomach. Host genetic factors contribute to the regulation of the inflammatory response and in the aggravation of mucosal damage. The harmful role of environmental factors is restricted to salt intake and smoking of tobacco. The ingestion of fruit and vegetables has some protective effect.

CONCLUSION

Infection with H. pylori is the major risk factor for gastric cancer development, and thus, eradication of the Helicobacter offers a promising best option for prevention of the disease. Bacterial virulence, host genetic factors, and environmental influences are interacting in the multifactorial process of gastric carcinogenesis.

Dual roles of CagA protein in Helicobacterpylori-induced chronic gastritis in mice

Cytotoxin-associated gene A (CagA) acts directly on gastric epithelial cells. However, the roles of CagA in host adaptive immunity against Helicobacter pylori (H. pylori) infection are not fully understood. In this study, to investigate the roles of CagA in the development of H. pylori-induced chronic gastritis, we used an adoptive-transfer model in which spleen cells from C57BL/6 mice with or without H. pylori infection were transferred into RAG2(-/-) mice, with gastric colonization of either CagA(+) H. pylori or CagA(-) H. pylori. Colonization of CagA(+) H. pylori but not CagA(-) H. pylori in the host gastric mucosa induced severe chronic gastritis in RAG2(-/-) mice transferred with spleen cells from H. pylori-uninfected mice. In addition, when CagA(+) H. pylori-primed spleen cells were transferred into RAG2(-/-) mice, CD4(+) T cell infiltration in the host gastric mucosa were observed only in RAG2(-/-) mice infected with CagA(+) H. pylori but not CagA(-) H. pylori, suggesting that colonization of CagA(+) H. pylori in the host gastric mucosa is essential for the migration of H. pylori-primed CD4(+) T cells. On the other hand, transfer of CagA(-) H. pylori-primed spleen cells into CagA(+) H. pylori-infected RAG2(-/-) mice induced more severe chronic gastritis with less Foxp3(+) regulatory T-cell infiltration as compared to transfer of CagA(+) H. pylori-primed spleen cells. In conclusion, CagA in the stomach plays an important role in the migration of H. pylori-primed CD4(+) T cells in the gastric mucosa, whereas CagA-dependent T-cell priming induces regulatory T-cell differentiation, suggesting dual roles for CagA in the pathophysiology of H. pylori-induced chronic gastritis.

Prevention of Gastric Cancer: When is Treatment of Helicobacter Pylori Warranted?

Chronic gastritis induced by Helicobacter pylori (H. pylori) is the strongest known risk factor for adenocarcinoma of the distal stomach, yet the effects of bacterial eradication on carcinogenesis remain unclear. H. pylori isolates possess substantial genotypic diversity, which engenders differential host inflammatory responses that influence clinical outcome. H. pylori strains that possess the cag pathogenicity island and secrete a functional cytotoxin induce more severe gastric injury and further augment the risk for developing distal gastric cancer. Carcinogenesis is also influenced by host genetic diversity, particularly involving immune response genes such as interleukin-1ß and tumor necrosis factor-α. Human trials and anima studies have indicated that eradication of H. pylori prior to the development of atrophic gastritis offers the best chance for prevention of gastric cancer. However, although the timing of intervention influences the magnitude of suppression of premalignant and neoplastic lesions, bacterial eradication, even in longstanding infections, is of clear benefit to the host. It is important to gain insight into the pathogenesis of H. pylori-induced gastritis and adenocarcinoma not only to develop more effective treatments for gastric cancer, but also because it might serve as a paradigm for the role of chronic inflammation in the genesis of other malignancies that arise within the gastrointestinal tract.

Gastric carcinoid in a patient infected with Helicobacter pylori: A new entity?

There are four types of gastric carcinoid tumors, classified according to their histology and malignant potential. Only a few cases of carcinoid tumors in patients infected with Helicobacter pylori (H. pylori) have been reported so far. We report a patient infected with H. pylori presenting with a small solitary gastric carcinoid tumor with very low proliferative rate and normal gastrin levels. The tumor was endoscopically removed and the patient received an eradication therapy against H. pylori. No signs of metastatic disease have been found so far during more than 3 year of follow-up. Infection with H. pylori may cause chronic gastritis with normal or elevated gastrin levels, leading to the development of gastric carcinoids by mechanisms unrelated to gastrin. Enterochromaffin-like cell tumors related to a chronic H. pylori infection may be considered as a distinct type of gastric carcinoid tumors.

Long-term administration of the fungus toxin, sterigmatocystin, induces intestinal metaplasia and increases the proliferative activity of PCNA, p53, and MDM2 in the gastric mucosa of aged Mongolian gerbils

OBJECTIVE

The causal agents of gastric cancer could include fungus toxins. Sterigmatocystin (ST), a fungus toxin, is a risk factor of gastric cancer. We investigated the effects of ST on the stomach tissues of Mongolian gerbils.

METHODS

Seventy-five-week-old male Mongolian gerbils received ST ad libitum at a concentration of 0 ppb (non-treated, n = 11), 100 ppb (n = 7), or 1000 ppb (n = 13) dissolved in drinking water for a period of 24 weeks. After administration, we tested the histopathological changes and immunostaining for proliferating cell nuclear antigen (PCNA), p53, and MDM2 expression.

RESULTS

We investigated the histopathological changes and determined the incidence of histopathological changes in animals with various gastric diseases after ST administration at a dose of 0 ppb (non-treated control), 100, or 1,000 ppb as follows: firstly, indices for gastritis were 18.2, 100, and 100%, those for erosion events were 9.1, 100, and 92.3%, and those for polyps were 0, 71.4, and 61.5%, respectively. These incidences in the ST-administered groups (100 or 1000 ppb) showed significant increases compared with those in the non-treated control group. And, lastly, indices for intestinal metaplasia were 0, 100, and 15.4%, respectively. Furthermore, immunostaining for PCNA, p53, and MDM2 expression showed significantly greater rates in the ST-administered groups (100 or 1000 ppb) than in the non-treated control group.

CONCLUSION

The histopathological and immunohistopathological findings of this study indicate that ST exerts a marked influence on gastric mucus and gland cells, showing dominant gastritis, erosion events, polyps, and intestinal metaplasia in these animals.

Identification of Helicobacter pylori strain cagPAI+ and cagPAI- Antigens by IgG antibodies from sera of experimentally colonized meriones unguiculatus (Mongolian gerbils)

BACKGROUND

 Mongolian gerbils that are experimentally infected with Helicobacter pylori develop a chronic inflammation that is similar to natural infections in humans. The aim of this study was to compare the antigens of H. pylori cagPAI+ and cagPAI- strains that are expressed during Meriones unguiculatus colonization.

MATERIALS AND METHODS

 We identified H. pylori cagPAI+ and cagPAI- strain antigens via Western blotting of samples from Mongolian gerbils that were subjected to unique, mixed, and sequential bacterial infections.

RESULTS

 The antigens from the J99/CG3 (cagPAI+) strain had a lower molecular weight than the antigens from the 251F/CG3 (cagPAI-) strain. There were fewer identified antigens in the single unique infections compared with the mixed and sequential infections. The number of recognized antigens that had a frequency of recognition >60% was higher for the simultaneous and sequential infection groups compared with the single infection group. A 57-kDa antigen was present in >60% of the samples and four of the five experimental groups. Antigens specific to each bacterial strain were identified; the 190- and 158-kDa antigens appear to be specific for cagPAI-, and the 70-kDa antigen appears to be specific for cagPAI+.

CONCLUSIONS

 In this study, we identified antigens that are common and specific to the H. pylori cagPAI+ and cagPAI- strains.

BabA-mediated adherence is a potentiator of the Helicobacter pylori type IV secretion system activity

Chronic infection of Helicobacter pylori in the stomach mucosa with translocation of the bacterial cytotoxin-associated gene A (CagA) effector protein via the cag-Type IV secretion system (TFSS) into host epithelial cells are major risk factors for gastritis, gastric ulcers, and cancer. The blood group antigen-binding adhesin BabA mediates the adherence of H. pylori to ABO/Lewis b (Le(b)) blood group antigens in the gastric pit region of the human stomach mucosa. Here, we show both in vitro and in vivo that BabA-mediated binding of H. pylori to Le(b) on the epithelial surface augments TFSS-dependent H. pylori pathogenicity by triggering the production of proinflammatory cytokines and precancer-related factors. We successfully generated Le(b)-positive cell lineages by transfecting Le(b)-negative cells with several glycosyltransferase genes. Using these established cell lines, we found increased mRNA levels of proinflammatory cytokines (CCL5 and IL-8) as well as precancer-related factors (CDX2 and MUC2) after the infection of Le(b)-positive cells with WT H. pylori but not with babA or TFSS deletion mutants. This increased mRNA expression was abrogated when Le(b)-negative cells were infected with WT H. pylori. Thus, H. pylori can exploit BabA-Le(b) binding to trigger TFSS-dependent host cell signaling to induce the transcription of genes that enhance inflammation, development of intestinal metaplasia, and associated precancerous transformations.

Evolution in an oncogenic bacterial species with extreme genome plasticity: Helicobacter pylori East Asian genomes

BACKGROUND

The genome of Helicobacter pylori, an oncogenic bacterium in the human stomach, rapidly evolves and shows wide geographical divergence. The high incidence of stomach cancer in East Asia might be related to bacterial genotype. We used newly developed comparative methods to follow the evolution of East Asian H. pylori genomes using 20 complete genome sequences from Japanese, Korean, Amerind, European, and West African strains.

RESULTS

A phylogenetic tree of concatenated well-defined core genes supported divergence of the East Asian lineage (hspEAsia; Japanese and Korean) from the European lineage ancestor, and then from the Amerind lineage ancestor. Phylogenetic profiling revealed a large difference in the repertoire of outer membrane proteins (including oipA, hopMN, babABC, sabAB and vacA-2) through gene loss, gain, and mutation. All known functions associated with molybdenum, a rare element essential to nearly all organisms that catalyzes two-electron-transfer oxidation-reduction reactions, appeared to be inactivated. Two pathways linking acetyl~CoA and acetate appeared intact in some Japanese strains. Phylogenetic analysis revealed greater divergence between the East Asian (hspEAsia) and the European (hpEurope) genomes in proteins in host interaction, specifically virulence factors (tipα), outer membrane proteins, and lipopolysaccharide synthesis (human Lewis antigen mimicry) enzymes. Divergence was also seen in proteins in electron transfer and translation fidelity (miaA, tilS), a DNA recombinase/exonuclease that recognizes genome identity (addA), and DNA/RNA hybrid nucleases (rnhAB). Positively selected amino acid changes between hspEAsia and hpEurope were mapped to products of cagA, vacA, homC (outer membrane protein), sotB (sugar transport), and a translation fidelity factor (miaA). Large divergence was seen in genes related to antibiotics: frxA (metronidazole resistance), def (peptide deformylase, drug target), and ftsA (actin-like, drug target).

CONCLUSIONS

These results demonstrate dramatic genome evolution within a species, especially in likely host interaction genes. The East Asian strains appear to differ greatly from the European strains in electron transfer and redox reactions. These findings also suggest a model of adaptive evolution through proteome diversification and selection through modulation of translational fidelity. The results define H. pylori East Asian lineages and provide essential information for understanding their pathogenesis and designing drugs and therapies that target them.

Pathophysiological functions of the CagA oncoprotein during infection by Helicobacter pylori

Infection with Helicobacter pylori cagA-positive strains plays an essential role in the development of gastric carcinoma. This review summarizes the pathophysiological functions of the cagA gene product, CagA, particularly focusing on the molecular mechanisms underlying CagA translocation into the host cells as well as CagA-mediated deregulation of host cell signaling.

Effects of blood group antigen-binding adhesin expression during Helicobacter pylori infection of Mongolian gerbils

Helicobacter pylori outer membrane proteins, such as the blood group antigen-binding adhesin (BabA), are associated with severe pathological outcomes. However, the in vivo role of BabA during long-term infection is not clear. In this study, Mongolian gerbils were infected with H. pylori and necropsied continuously during 18 months. Bacterial clones were recovered and analyzed for BabA expression, Leb-binding activity, and adhesion to gastric mucosa. BabA expression was completely absent by 6 months post-infection. Loss of BabA expression was attributable to nucleotide changes within the babA gene that resulted in a truncated BabA. In response to the infection, changes in the epithelial glycosylation pattern were observed that were similar to responses observed in humans and monkeys. Furthermore, infections with BabA-expressing and BabA-nonexpressing H. pylori showed no differences in colonization, but infection with the BabA-expressing strain exhibited histological changes and increased inflammatory cell infiltration. This suggests that BabA expression contributes to severe mucosal injury.

The struggle within: microbial influences on colorectal cancer

Recently, an unprecedented effort has been directed at understanding the interplay between chronic inflammation and development of cancer, with the case of inflammatory bowel disease (IBD)-associated colorectal cancer at the forefront of this research endeavor. The last decade has been particularly fertile, with the discovery of numerous innovative paradigms linking various inflammatory, proliferative, and innate and adaptive immune signaling pathways to the development of colorectal cancer. Because of the preponderant role of the intestinal microbiota in the initiation and progression of IBD, recent efforts have been directed at understanding the relationship between bacteria and colorectal cancer. The microbiota and its collective genome, the microbiome, form a diverse and complex ecological community that profoundly impacts intestinal homeostasis and disease states. This review will discuss the differential influence of the microbiota on the development of IBD-associated colorectal cancer and highlight the role of innate immune sensor-dependent as well as -independent mechanisms in this pathology.

Animal models to study the role of long-term hypergastrinemia in gastric carcinogenesis

Patients with chronic hypergastrinemia due to chronic atrophic gastritis or gastrinomas have an increased risk of developing gastric malignancy, and it has been questioned whether also patients with hypergastrinemia caused by long-term use of acid inhibiting drugs are at risk. Gastric carcinogenesis in humans is affected by numerous factors and progresses slowly over years. When using animal models with the possibility of intervention, a complex process can be dissected by studying the role of hypergastrinemia in carcinogenesis within a relatively short period of time. We have reviewed findings from relevant models where gastric changes in animal models of long-term hypergastrinemia have been investigated. In all species where long-term hypergastrinemia has been induced, there is an increased risk of gastric malignancy. There is evidence that hypergastrinemia is a common causative factor in carcinogenesis in the oxyntic mucosa, while other cofactors may vary in the different models.

A Tale of Two Toxins: Helicobacter Pylori CagA and VacA Modulate Host Pathways that Impact Disease

Helicobacter pylori is a pathogenic bacterium that colonizes more than 50% of the world's population, which leads to a tremendous medical burden. H. pylori infection is associated with such varied diseases as gastritis, peptic ulcers, and two forms of gastric cancer: gastric adenocarcinoma and mucosa-associated lymphoid tissue lymphoma. This association represents a novel paradigm for cancer development; H. pylori is currently the only bacterium to be recognized as a carcinogen. Therefore, a significant amount of research has been conducted to identify the bacterial factors and the deregulated host cell pathways that are responsible for the progression to more severe disease states. Two of the virulence factors that have been implicated in this process are cytotoxin-associated gene A (CagA) and vacuolating cytotoxin A (VacA), which are cytotoxins that are injected and secreted by H. pylori, respectively. Both of these virulence factors are polymorphic and affect a multitude of host cellular pathways. These combined facts could easily contribute to differences in disease severity across the population as various CagA and VacA alleles differentially target some pathways. Herein we highlight the diverse types of cellular pathways and processes targeted by these important toxins.

Antibacterial and ulcer healing effects of organoselenium compounds in naproxen induced and Helicobacter pylori infected Wistar rat model

Aim of the present study was to evaluate in vitro toxicity and in vivo antibacterial, anti-inflammatory, antiulcer, and antioxidant activities of two organoselenium compounds, selenocystine (SeCys) and ebselen (Ebs). The study was conducted in experimentally induced ulcers in rodent model infected with Helicobacter pylori (H. pylori). In vitro toxicological studies on normal splenic lymphocytes revealed that SeCys and Ebs were non-toxic to the cells even at 100 μM concentration. Antibacterial activity was observed at 500 μg/mL concentration of either of the compounds against H. pylori. In vivo studies after treatment with SeCys and Ebs (500 μg/kg/day) resulted in significant reduction in ROS production and inhibition of lipid peroxidation in gastric tissue. The antioxidant and anti-inflammatory activities of both the compounds were also confirmed by their ability to lower GSH reduction, to induce the expression of antioxidant genes such as GPx-4, and MnSOD and to suppress inflammatory genes namely COX-2, TNF-α and TGF-β. In addition, the immunomodulatory activity of both the compounds was evident by enhance of the CD4 levels and maintenance of the IgG, IL-6 and IL-10 levels. Persistent treatment (500 μg/kg, for 28 days) with both the compounds showed considerable (p<0.05) ulcer healing property supporting its role in gastro protection. In conclusion, the results of our study suggest that both SeCys and Ebs possess broad spectrum of activities without any potential toxicity.

New frontiers in gut nutrient sensor research: prophylactic effect of glutamine against Helicobacter pylori-induced gastric diseases in Mongolian gerbils

Ammonia is one of the important toxins produced by Helicobacter pylori (H. pylori), the major cause of peptic ulcer diseases. We examined whether glutamine or marzulene (a gastroprotective drug containing 1% sodium azulene and 99% glutamine) protects the gastric mucosa against H. pylori in vivo and investigated the mechanism underlying glutamine-induced mucosal protection against ammonia in gastric epithelial cells in vitro. Mongolian gerbils were fed for 3 months with a diet containing glutamine (2%-20%) or marzulene (20%) starting from 2 weeks or 2 years after H. pylori infection. Then, gastric mucosal changes were evaluated both macro- and microscopically. Cultured gastric epithelial cells were incubated in the presence of ammonia, with or without glutamine; and cell viability, ammonia accumulation, and chemokine production were determined. Gerbils exhibited edema, congestion, and erosion after 3-month infection; and after 2-year infection, they showed cancer-like changes in the gastric mucosa. Glutamine and marzulene significantly suppressed these pathological changes caused in the gastric mucosa by H. pylori infection. Ammonia was accumulated in the cells, resulting in an increase in chemokine production and a decrease in cell viability. These pathological responses were prevented by glutamine. In addition, glutamine decreased chemokine production and cell death through inhibition of cellular accumulation of ammonia, resulting in the prevention of H. pylori-induced gastric diseases in vivo. These results suggest that glutamine/marzulene would be useful for prophylactic treatment of H. pylori-induced gastric diseases in patients.

Gastric cancer, Helicobacter pylori infection and other risk factors

Gastric cancer incidence is declining. However, it is too early to consider this neoplastic disease as rare and the worldwide mortality rate still remains high. Several risk factors have been identified for non-cardia gastric cancer and primary prevention is feasible since most of the risk factors can be removed. Helicobacter pylori eradication treatment reduces but does not abolish gastric cancer risk. Indeed, gastric cancer is a multifactorial disease and removing one factor does not therefore prevent all cases. Endoscopic surveillance is still needed, especially in subjects at higher risk. The definition of high-risk patients will be the future challenge as well as identifying the best surveillance strategy for such patients.

Role of innate immunity in Helicobacter pylori-induced gastric malignancy

Helicobacter pylori colonizes the majority of persons worldwide, and the ensuing gastric inflammatory response is the strongest singular risk factor for peptic ulceration and gastric cancer. However, only a fraction of colonized individuals ever develop clinically significant outcomes. Disease risk is combinatorial and can be modified by bacterial factors, host responses, and/or specific interactions between host and microbe. Several H. pylori constituents that are required for colonization or virulence have been identified, and their ability to manipulate the host innate immune response will be the focus of this review. Identification of bacterial and host mediators that augment disease risk has profound ramifications for both biomedical researchers and clinicians as such findings will not only provide mechanistic insights into inflammatory carcinogenesis but may also serve to identify high-risk populations of H. pylori-infected individuals who can then be targeted for therapeutic intervention.

When bacteria become mutagenic and carcinogenic: lessons from H. pylori

More and more convincing data link bacteria to the development of cancers. How bacteria act as mutagens by altering host genomes, what are the different strategies they develop and what consequences do they have on infection-associated pathogenesis are the main questions addressed in this review, which focuses in particular on Helicobacter pylori infection. H. pylori is a major risk factor for gastric cancer development. Its oncogenic role is mediated by the chronic active inflammation it elicits in the gastric mucosa, associated with its capacity to persistently colonize the human stomach. However, direct genotoxicity of H. pylori through the action of bacterial cytotoxin or resulting from a DNA damaging effect of its metabolic derivatives as nitroso compounds cannot be excluded. Numerous studies have investigated inflammation-associated DNA damaging activity and mutagenic response due to H. pylori infection in both human and animal models. Recent findings on its mutagenic effects at the nuclear and mitochondrial genome and related DNA damage are reviewed. This genotoxic activity associated with oxidative species produced during inflammation is linked to the decreased efficiency of DNA repair systems. DNA methylation, which plays an important role in the regulation of the host response to H. pylori infection, is also documented. Furthermore, H. pylori affects genome integrity by increasing activation-induced cytidine deaminase (AID), a DNA/RNA editing cytidine deaminase linking mutagenesis and tumorigenesis. These different strategies occurring during bacteria-host cell interaction, lead to nucleotide modifications and genome instabilities recognized as early events in the carcinogenesis process and contribute to the oncogenic properties of H. pylori infection.

Helicobacter pylori in the pathogenesis of gastric cancer and gastric lymphoma

Chronic gastric infection by the gram-negative bacterium Helicobacter pylori is strongly associated with the development of distal gastric carcinoma and gastric mucosal lymphoma in humans. Eradication of H. pylori with combination antibiotic therapy cures most cases of gastric lymphoma and slows progression to gastric adenocarcinoma. H. pylori promotes gastric neoplasia, principally via the induction of an intense gastric inflammatory response that lasts over decades. This persistent inflammatory state produces chronic oxidative stress and adaptive changes in gastric epithelial and immune cell pathobiology that in a minority of infected subjects eventually proceeds to frank neoplastic transformation.

CagA(+) H. pylori induces Akt1 phosphorylation and inhibits transcription of p21(WAF1/CIP1) and p27(KIP1) via PI3K/Akt1 pathway

OBJECTIVE

Cytotoxin-associated protein (CagA) of H. pylori has been confirmed to be closely associated with gastric inflammation and tumorigenesis, but the mechanism behind it is little understood. In this study, we try to determine roles of CagA(+) strain in activating PI3K/Akt1 signaling pathway, and affecting expression of p21(WAF1/CIP1) and p27(KIP1), and also in releasing IL-8 in host cells.

METHODS

Akt1 phosphorylation and IL-8 levels of CagA(+) and CagA⁻ strain infected AGS cells were detected by ELISAs. Two quantitative RT-PCRs were established to measure p21(WAF1/CIP1) and p27(KIP1) mRNA levels in the CagA(+) and CagA⁻ strain infected cells. LY294002, an inhibitor of PI3K/Akt pathway, was used to define effect of the pathway in IL-8 release.

RESULTS

CagA(+) strain could induce an obvious elevation of Akt1 phosphorylation in the infected AGS cells while CagA? strain failed to do so. The CagA(+) H. pylori strain infected AGS cells showed significant drops both in p21(WAF1/CIP1) and p27(KIP1) mRNA levels, whereas the CagA⁻ H. pylori strain caused a remarkable increase in p21(WAF1/CIP1) mRNA without affecting p27(KIP1) gene transcription in the AGS cells. Both the CagA(+) and CagA⁻ H. pylori strains enabled AGS cells to produce close elevated levels of IL-8, and the LY294002 block resulted in unexpected elevations of IL-8 levels.

CONCLUSIONS

CagA can activate PI3K/Akt1 pathway that plays an inhibitory role in IL-8 release in H. pylori infected AGS cells. Activation of PI3K/Akt1 pathway and subsequent negative regulation of p21(WAF1/CIP1) and p27(KIP1) expression might be involved in CagA-associated carcinogenesis.

Relationship between H.Pylori infection and clinicopathological features and prognosis of gastric cancer

Background

Aimed to assess the relationship between H.Pylori and the clinicopathological features and prognosis of gastric cancer by quantitative detection of H.Pylori.

Methods

157 patients were enrolled, all patients had a record of clinicopathological parameters. Specimens including the tumor and non-neoplastic were detected for H.Pylori by Real-Time PCR and analyzed clinical data retrospectively. Variables independently affecting prognosis were investigated by means of multivariate analysis using the Cox proportional hazards model.

Results

H.Pylori infection was greater in non-neoplastic tissue than the tumor tissue (p < 0.05), H.Pylori infection and its copies were related to the tumor site and N staging (p < 0.05). Overall survival (OS) in all 157 patients has no correlation with the H.Pylori infection status (p = 0.715). As to the patients who underwent a curative surgery, relapse-free survival (RFS) has no correlation with the H.Pylori infection status (p = 0.639). Among the H.Pylori positive patients, OS and RFS of those with higher copies were longer than in patients with low copies, but there was no significant statistical difference.

Conclusions

H.Pylori infection status and its copies were related to N staging. The OS and RFS in patients with positive H.Pylori status has no significant difference from the patients with negative H.Pylori status.

Rapid paper disk test for identification of Helicobacter pylori in mixed cultures of gerbil gastric homogenates

A method denominated rapid paper disk test (RPDT) was developed to identify H. pylori colonies in complex cultures obtained from gerbil gastric homogenates. Identification is based on a characteristic reaction pattern (RP) for H. pylori colonies given by the combination of the urease-oxidase activities on a paper disk. Compared to the RPs obtained from gerbil's intestinal tract isolated bacteria, H. pylori RP is completely distinguishable, even from those of bacteria that share one or both activities as are Aerococcus urinae, Bacillus sphaericus, Bacillus brevis, Corynebacterium pseudogenitalium, and Staphylococcus simulans, as well as from those produced by collection strains Proteus vulgaris and Pseudomonas aeruginosa. This method allows the practical quantification of H. pylori colonies in highly contaminated plates. RPDT has the following advantages over other methodologies that use indicators in the medium: it employs two of the three routinely used H. pylori biochemical identification tests, the reagents do not interfere with bacterial viability, there are no restrictions in relation to the medium used, and it is a simple, fast, and low-cost method.

Role of interleukin polymorphisms in gastric cancer: "Pros and cons"

Helicobacter pylori (H. pylori) infection is the leading cause of gastric cancer worldwide. Infection with this bacterium causes a chronic active immune response that persists for the life of the host. The combination of bacterial factors, environmental insults, and the host immune response drives the initiation and progression of mucosal atrophy, metaplasia, and dysplasia toward GC. Among the host factors, IL-1 gene cluster polymorphisms (IL-1B encoding IL-1β and IL-1RN encoding IL-1ra, its naturally occurring receptor antagonist) play a decisive role in modulating the risk of developing hypochlorhydria, gastric atrophy and GC in the presence of H. pylori infection. In particular, one single nucleotide polymorphism in the IL-1B promoter (IL-1B-511C⁄T), and the short allele of a 86-bp variable number of tandem repeats polymorphism in the IL-1RN second intron (IL-1RN*2) are associated with an increased risk for GC. However this hypothesis is still to be fully confirmed. This review focuses on the divergent results obtained by several epidemiological and functional in vitro and in vivo studies and show that IL-1 genotyping has still no role in the clinical management of patients with H. pylori infection.

Pathophysiology of intestinal metaplasia of the stomach: emphasis on CDX2 regulation

IM (intestinal metaplasia) of the stomach is a pre-neoplastic lesion that usually follows Helicobacter pylori infection and that confers increased risk for gastric cancer development. After setting the role played by CDX2 (Caudal-type homeobox 2) in the establishment of gastric IM, it became of foremost importance to unravel the regulatory mechanisms behind its de novo expression in the stomach. In the present paper, we review the basic pathology of gastric IM as well as the current knowledge on molecular pathways involved in CDX2 regulation in the gastric context.

Establishment of a mouse model of chronic Helicobacter pylori infection-induced gastric adenocarcinoma and investigation of the effect of Helicobacter pylori infection on angiogenesis

AIM: To investigate the carcinogenicity of long-term Helicobacter pylori (H.pylori) infection in C57BL/6 mice and to investigate the role of angiogenesis in the pathogenesis of H.pylori infection-induced gastric cancer.

METHODS: Eighty male C57BL/6 mice of SPF grade were equally and randomly divided into normal group and model group. The normal group was fed normally, while the model group was inoculated by oral gavage with H.pylori SS1. Mice were sacrificed at weeks 10, 25, 45 and 72 after the last inoculation. H.pylori infection was analyzed by rapid urease test and Giemsa staining. The pathological changes in the gastric mucosa of mice were assessed by hematoxylin-eosin staining. Microvessel density (MVD) was detected by immunohistochemistry.

RESULTS: No H.pylori infection was detected in the gastric antrum, gastric body and duodenal mucosa in the normal group. The rates of H.pylori colonization were 88.9%, 100%, 100% and 100% at weeks 10, 25, 45 and 72 in the model group. At week 72, the incidence rates of chronic gastritis, atrophic gastritis, intestinal metaplasia, dysplasia and gastric cancer were 100%, 88.9%, 77.8%, 33.3% and 22.2% in the model group, respectively. The MVD in the gastric mucosa in the model group was 18.56 ± 2.62, significantly higher than that in the normal group (P < 0.01).

CONCLUSION: A mouse model of chronic H.pylori infection-induced gastric adenocarcinoma has been established successfully. H.pylori infection can increase the MVD in the gastric mucosa in C57BL/6 mice and therefore play an important role in the development of gastric cancer.

Helicobacter pylori adhesion to gastric epithelial cells is mediated by glycan receptors

Helicobacter pylori adhesion to gastric epithelial cells constitutes a key step in the establishment of a successful infection of the gastric mucosa. The high representation of outer membrane proteins in the bacterial genome suggests the relevance of those proteins in the establishment of profitable interactions with the host gastric cells. Gastric epithelial cells are protected by a mucous layer gel, mainly consisting of the MUC5AC and MUC6 mucins. In addition to this protective role, mucins harbor glycan-rich domains that constitute preferential binding sites of many pathogens. In this article we review the main players in the process of H. pylori adhesion to gastric epithelial cells, which contribute decisively to the high prevalence and chronicity of H. pylori infection. The BabA adhesin recognizes both H-type 1 and Lewis b blood-group antigens expressed on normal gastric mucosa of secretor individuals, contributing to the initial steps of infection. Upon colonization, persistent infection induces an inflammatory response with concomitant expression of sialylated antigens. The SabA adhesin mediates H. pylori binding to inflamed gastric mucosa by recognizing sialyl-Lewis a and sialyl-Lewis x antigens. The expression of the BabA and SabA adhesins is tightly regulated, permitting the bacteria to rapidly adapt to the changes of glycosylation of the host gastric mucosa that occur during infection, as well as to escape from the inflammatory response. The growing knowledge of the interactions between the bacterial adhesins and the host receptors will contribute to the design of alternative strategies for eradication of the infection.

The versatility of Helicobacter pylori CagA effector protein functions: The master key hypothesis

Several bacterial pathogens inject virulence proteins into host target cells that are substrates of eukaryotic tyrosine kinases. One of the key examples is the Helicobacter pylori CagA effector protein which is translocated by a type-IV secretion system. Injected CagA becomes tyrosine-phosphorylated on EPIYA sequence motifs by Src and Abl family kinases. CagA then binds to and activates/inactivates multiple signaling proteins in a phosphorylation-dependent and phosphorylation-independent manner. A recent proteomic screen systematically identified eukaryotic binding partners of the EPIYA phosphorylation sites of CagA and similar sites in other bacterial effectors by high-resolution mass spectrometry. Individual phosphorylation sites recruited a surprisingly high number of interaction partners suggesting that each phosphorylation site can interfere with many downstream pathways. We now count 20 reported cellular binding partners of CagA, which represents the highest quantitiy among all yet known virulence-associated effector proteins in the microbial world. This complexity generates a highly remarkable and puzzling scenario. In addition, the first crystal structure of CagA provided us with new information on the function of this important virulence determinant. Here we review the recent advances in characterizing the multiple binding signaling activities of CagA. Injected CagA can act as a 'master key' that evolved the ability to highjack multiple host cell signalling cascades, which include the induction of membrane dynamics, actin-cytoskeletal rearrangements and the disruption of cell-to-cell junctions as well as proliferative, pro-inflammatory and anti-apoptotic nuclear responses. The discovery that different pathogens use this common strategy to subvert host cell functions suggests that more examples will emerge soon.

Brugia filariasis differentially modulates persistent Helicobacter pylori gastritis in the gerbil model

In select Helicobacter pylori-infected populations with low gastric cancer, nematode coinfections are common and both helicobacter gastritis and filariasis are modeled in gerbils. We evaluated gastritis, worm counts, tissue cytokine gene expression levels and Th1/Th2-associated antibody responses in H. pylori and Brugia pahangi mono- and coinfected gerbils. H. pylori-associated gastritis indices were significantly lower 21 weeks post-infection in coinfected gerbils (p < or = 0.05) and were inversely proportional to worm counts (r(2) = -0.62, p < 0.003). Additionally, IFN-gamma, IL-1 beta, CXCL1, IL-4 and IL-10 mRNA levels in the gastric antrum reflected a significant host response to gastric H. pylori and as well as systemic filariasis (p < or = 0.05). Despite increasing worm burden (p < 0.05), gastritis progressed in coinfected gerbils (p < 0.03) becoming equivalent to H. pylori-infected gerbils at 42 weeks (p = 0.7). Pro- and anti-inflammatory mediator mRNA levels were notably downregulated in B. pahangi infected gerbils below uninfected control values, suggesting hyporesponsiveness to B. pahangi. Consistent with an increasing Th1 response to H. pylori, IgG2a (p < 0.01), IL-1 beta (p = 0.04) and CXCL1 (p = 0.006) responses significantly increased and IL-4 (p = 0.05) and IL-10 (p = 0.04) were decreased in coinfected gerbils at 42 weeks. Initial systemic responses to B. pahangi resulted in attenuated gastritis in coinfected gerbils, but subsequent filarid-associated hyporesponsiveness appears to have promoted H. pylori gastritis.

Sequencing, annotation, and comparative genome analysis of the gerbil-adapted Helicobacter pylori strain B8

BACKGROUND

The Mongolian gerbils are a good model to mimic the Helicobacter pylori-associated pathogenesis of the human stomach. In the current study the gerbil-adapted strain B8 was completely sequenced, annotated and compared to previous genomes, including the 73 supercontigs of the parental strain B128.

RESULTS

The complete genome of H. pylori B8 was manually curated gene by gene, to assign as much function as possible. It consists of a circular chromosome of 1,673,997 bp and of a small plasmid of 6,032 bp carrying nine putative genes. The chromosome contains 1,711 coding sequences, 293 of which are strain-specific, coding mainly for hypothetical proteins, and a large plasticity zone containing a putative type-IV-secretion system and coding sequences with unknown function. The cag-pathogenicity island is rearranged such that the cagA-gene is located 13,730 bp downstream of the inverted gene cluster cagB-cag1. Directly adjacent to the cagA-gene, there are four hypothetical genes and one variable gene with a different codon usage compared to the rest of the H. pylori B8-genome. This indicates that these coding sequences might be acquired via horizontal gene transfer.The genome comparison of strain B8 to its parental strain B128 delivers 425 unique B8-proteins. Due to the fact that strain B128 was not fully sequenced and only automatically annotated, only 12 of these proteins are definitive singletons that might have been acquired during the gerbil-adaptation process of strain B128.

CONCLUSION

Our sequence data and its analysis provide new insight into the high genetic diversity of H. pylori-strains. We have shown that the gerbil-adapted strain B8 has the potential to build, possibly by a high rate of mutation and recombination, a dynamic pool of genetic variants (e.g. fragmented genes and repetitive regions) required for the adaptation-processes. We hypothesize that these variants are essential for the colonization and persistence of strain B8 in the gerbil stomach during in ammation.

Detailed in vivo analysis of the role of Helicobacter pylori Fur in colonization and disease

Helicobacter pylori persistently colonizes the harsh and dynamic environment of the stomach in over one-half of the world's population and has been identified as a causal agent in a spectrum of pathologies that range from gastritis to invasive adenocarcinoma. The ferric uptake regulator (Fur) is one of the few regulatory proteins that has been identified in H. pylori. Fur regulates genes important for acid acclimation and oxidative stress and has been shown to be important for colonization of H. pylori in both murine and Mongolian gerbil models of infection. To more thoroughly define the role of Fur in vivo, we conducted an extensive temporal analysis of the location of, competitive ability of, and resultant pathology induced by a Deltafur strain in the Mongolian gerbil model of infection and compared the results to results for its wild-type parent. We found that at the earliest time points postinfection, significantly more Deltafur bacteria than wild-type bacteria were recovered. However, this trend was reversed by day 3, when there was significantly increased recovery of the wild-type strain. The increased recovery of the Deltafur strain at 1 day postinfection reflected increased recovery from both the corpus and the antrum of the stomach. When the wild-type strain was allowed to colonize first, the Deltafur strain was unable to compete for colonization at any time postinfection. However, when the Deltafur strain was allowed to colonize first, the wild type efficiently outcompeted the Deltafur strain only at early times postinfection. Finally, we demonstrated that there was a delay in the development and severity of inflammation and pathology of the Deltafur strain in the gastric mucosa even after comparable levels of colonization occurred. Together, these data indicate that H. pylori Fur is most important at early stages of infection and illustrate the importance of the ability of H. pylori to adapt to its constantly fluctuating environment when it is establishing infection, inflammation, and disease.

Angiogenesis and lymphangiogenesis of gastric cancer

Tumor angiogenesis is the result of an imbalance between positive and negative angiogenic factors released by tumor and host cells into the microenvironment of the neoplastic tissue. The stroma constitutes a large part of most solid tumors, and cancer-stromal cell interactions contribute functionally to tumor growth and metastasis. Activated fibroblasts and macrophages in tumor stroma play important roles in angiogenesis and tumor progression. In gastric cancer, tumor cells and stromal cells produce various angiogenic factors, including vascular endothelial growth factor, interleukin-8, platelet-derived endothelial cell growth factor, and angiopoietin. In addition, Helicobacter pylori infection increases tumor cell expression of metastasis-related genes including those encoding several angiogenic factors. We review the current understanding of molecular mechanisms involved in angiogenesis and lymphangiogenesis of human gastric cancer.

Helicobacter pylori CagA phosphorylation status determines the gp130-activated SHP2/ERK and JAK/STAT signal transduction pathways in gastric epithelial cells

The Helicobacter pylori protein CagA may undergo tyrosine phosphorylation following its entry into human gastric epithelial cells with downstream effects on signal transduction. Disruption of the gp130 receptor that modulates the balance of the SHP2/ERK and JAK/STAT pathways enhanced peptic ulceration and gastric cancer in gp130 knock-out mice. In this study, we evaluated the effect of translocated CagA in relation to its tyrosine phosphorylation status on the gp130-mediated signal switch between the SHP2/ERK and JAK/STAT3 pathways. We showed that in the presence of CagA, SHP2 was recruited to gp130. Phosphorylated CagA showed enhanced SHP2 binding activity and ERK1/2 phosphorylation, whereas unphosphorylated CagA showed preferential STAT3 activation. These findings indicate that the phosphorylation status of CagA affects the signal switch between the SHP2/ERK and JAK/STAT3 pathways through gp130, providing a novel mechanism to explain H. pylori signaling.

Association of TGF-β1 expression in gastric mucosa with Helicobacter pylori infection and changes in peripheral blood T lymphocyte subsets during gastric carcinogenesis

AIM: To investigate the association of transforming growth factor-beta 1 (TGF-β1) expression in gastric mucosa with Helicobacter pylori (H.pylori) infection and changes in peripheral blood T lymphocyte subsets in patients with gastric precancerous lesions at different stages.

METHODS: Seventy-two gastric mucosa specimens were taken gastroscopically from patients with gastric precancerous lesions at different stages. H.pylori infection was evaluated by rapid urease test (RUT) in combination with Giemsa staining. The expression of TGF-β1 in gastric mucosa was detected by immunohistochemistry. The T lymphocyte subsets in peripheral blood were measured by flow cytometry .

RESULTS: The positive rates of TGF-β1 expression in chronic superficial gastritis (CSG), chronic atrophic gastritis (CAG), intestinal metaplasia and atypical dysplasia (IM/Dy), and gastric carcinoma (GC) were 39.1%, 52.6%, 62.3% and 87.5%, respectively. The positive rate of TGF-β1 expression in CSG was significantly lower than that in IM/Dy (P < 0.05). In patients with IM/Dy, the positive rate of TGF-β1 expression in H.pylori-positive patients was higher than that in H.pylori-negative ones (P < 0.05). The percentages of CD3⁺, CD4⁺ and CD4+/CD8⁺ T lymphocytes were significantly lower in patients with GC than in patients with CSG (all P < 0.05 or 0.01). The percentages of CD4⁺ and CD4⁺/CD8⁺ T lymphocytes in patients with IM/Dy were lower than those in patients with CSG (both P < 0.01). The positive rate of TGF-β1 expression was negatively correlated with the percentages of CD3⁺, CD4 and CD4⁺/CD8⁺ T lymphocytes in patients with gastric precancerous lesions.

CONCLUSION: The expression of TGF-β1 gradually increases and cellular immune function is gradually weakened during the evolution from CSG to GC. The suppressive effects of TGF-β1 on cellular immune function can partly explain why patients with IM/Dy have lower cellular immune function.

Early-onset gastric cancer: Learning lessons from the young

There is by no means a clear-cut pattern of mutations contributing to gastric cancers, and gastric cancer research can be hampered by the diversity of factors that can induce gastric cancer, such as Helicobacter pylori infection, diet, ageing and other environmental factors. Tumours are unquestionably riddled with genetic changes yet we are faced with an unsolvable puzzle with respect to a temporal relationship. It is postulated that inherited genetic factors may be more important in early-onset gastric cancer (EOGC) than in gastric cancers found in older patients as they have less exposure to environmental carcinogens. EOGC, therefore, could provide a key to unravelling the genetic changes in gastric carcinogenesis. Gastric cancers occurring in young patients provide an ideal background on which to try and uncover the initiating stages of gastric carcinogenesis. This review summarizes the literature regarding EOGC and also presents evidence that these cancers have a unique molecular-genetic phenotype, distinct from conventional gastric cancer.

Gastric Infection with Kazachstania heterogenica influences the outcome of a Helicobacter suis infection in Mongolian gerbils

BACKGROUND

The Mongolian gerbil model is often used to investigate the interactions between different gastric Helicobacter species and the gastric tissue. A preliminary screening of a gerbil population intended for use in Helicobacter suis infection studies revealed a natural yeast infection in the stomach of these animals. After identification, we have investigated the effect of the gastric yeast infection on the outcome of an experimental H. suis infection in Mongolian gerbils.

MATERIALS AND METHODS

Yeast cells were isolated from the stomachs of Mongolian gerbils. Identification was done by Internally Transcribed rRNA Spacer 2 Region PCR fragment length analysis. To investigate a possible pathologic role of this yeast, Mongolian gerbils were infected experimentally with this yeast. Co-infection with the newly isolated H. suis was performed to investigate possible interactions between both micro-organisms.

RESULTS

Kazachstania heterogenica was found colonizing the stomach of Mongolian gerbils, mainly in the antrum. Few pathologic changes were seen in the stomachs of infected animals. Experimental co-infection of gerbils with this yeast and the newly isolated H. suis showed a significant increase in inflammation in animals infected with both micro-organisms compared to animals infected only with H. suis.

CONCLUSIONS

K. heterogenica colonizes the stomach of Mongolian gerbils in exactly the same regions as gastric Helicobacter species. The uncontrolled presence of this yeast in the gerbil stomach can lead to an overestimation of the inflammation caused by Helicobacter in this animal model.

Role of Helicobacter pylori infection in gastric cancer pathogenesis: a chance for prevention

Gastric cancer in the absence of strategies implemented for early detection continues to have a dismal prognosis. There are limited options for a curative therapy once patients present with clinical manifestations of this malignant disease. Helicobacter pylori (H. pylori) infection plays a key role in gastric carcinogenesis, supported by epidemiological, preclinical and clinical studies. The recognition of H. pylori infection as a critical risk factor in the development of gastric cancer opens the chance for new venues in prevention strategies.

The Mongolian gerbil as a model for inflammatory bowel disease

Mongolian gerbils are used as biomedical research models for a variety of diseases and are in some cases suited better than other rodents for basic research and therapeutic studies. The aim of this study was to establish and characterize a dextran sulphate sodium (DSS)-induced model in gerbils for the human inflammatory bowel disease (IBD) and to utilize them for a therapeutic study in vivo. Four concentrations (0.5%, 1%, 2% and 4%) of DSS were administered via drinking water for 7 days; based on these results, a concentration of 3% DSS was given for 9 days in a second approach. Fluid uptake and general clinical condition were assessed daily using a clinical score. Caecum and colon were scored histologically. Fluid uptake was affected by addition of DSS to the drinking water. First clinical symptoms were observed at day 4 of DSS treatment with a considerable increase in clinical score parameters only in gerbils receiving 2% or 4% DSS. Histologically, ulceration and inflammation were observed predominantly in the caecum of gerbils treated with at least 1% DSS; reproducible inflammation in the colon required at least 2% DSS. Using 3% DSS for 9 days, considerably more inflammation was induced in the colon, comparable with lesions usually observed in the mouse model. Using an optimized protocol, DSS treatment induces reproducibly typhlocolitis in Mongolian gerbils, rendering them as a useful model for IBD.

Angiotensin II receptor expression and relation to Helicobacter pylori-infection in the stomach of the Mongolian gerbil

Background

The role of the renin-angiotensin system in gastric physiology and disease has as yet been sparsely explored. The first aim of the study was to investigate the baseline presence and location of angiotensin II receptors (AT1R and AT2R) in the stomach of the Mongolian gerbil. A second aim was to elucidate whether the presence of H. pylori infection is associated with changes in the expression of these receptors.

Methods

H. pylori-negative and H. pylori-infected (strain SS1 or TN2GF4) male Mongolian gerbils were investigated. The stomachs were examined at six or 12 months after inoculation by the use of immunohistochemistry, western blot and microscopic morphometry.

Results

AT1R and AT2R were located in a variety of cells in the gerbil gastric wall, including a subpopulation of endocrine cells in the antral mucosa and inflammatory cells infiltrating H. pylori-infected stomachs. Gerbils infected with the SS1 strain showed a significantly increased antral AT1R protein expression and an increased number of infiltrating polymorphonuclear leucocytes (PMNs) at 12 months. The AT1R protein expression correlated with the number of PMNs and the antral expression of myeloperoxidase.

Conclusions

Angiotensin II receptors are present in a variety of cells in the gastric wall of the Mongolian gerbil. The results indicate an influence dependent on the H. pylori strain on the gastric AT1R expression and a relationship between gastric AT1R expression and mucosal PMNs infiltration.