Helicobacter pylori related hypergastrinaemia is the result of a selective increase in gastrin 17

How did the ancient bacterium, Helicobacter pylori, cause an epidemic of chronic duodenal ulceration?

The association of Helicobacter pylori with chronic duodenal ulceration was a seminal observation in the short history of gastroenterology. However, H. pylori is now known to be an ancient bacterium, whereas there is persuasive evidence that the epidemic of duodenal ulceration began in the second half of the 19th century and continued into the second half of the 20th century. Possible explanations for the epidemic include genomic changes in the organism and environmental or other influences on the human host. While genomic changes resulted in the appearance of virulence factors, these seem likely to have appeared thousands of years ago with minimal effects on gastritis because of coexisting suppression of gastric immunity. In contrast, the emergence of duodenal ulceration is best explained by a change in the pattern of gastritis from inflammation involving the antrum and body in most individuals to a significant minority (10-20%) with antral gastritis but with relative sparing of the body of the stomach. In the latter group, the increase in serum gastrin (particularly G17) associated with antral gastritis had trophic effects on gastric parietal cells with an increase in the parietal cell mass and hypersecretion of gastric acid. Hypersecretion of acid is seen as the major risk factor for duodenal ulceration with significant contributions from environmental factors including smoking and use of nonsteroidal, anti-inflammatory drugs. Host factors favoring changes in the pattern of gastritis include delayed acquisition of infection and improved nutrition; both with enhancing effects on mucosal immunity.

Dietary factors modulate Helicobacter-associated gastric cancer in rodent models

Since its discovery in 1982, the global importance of Helicobacter pylori-induced disease, particularly in developing countries, remains high. The use of rodent models, particularly mice, and the unanticipated usefulness of the gerbil to study H. pylori pathogenesis have been used extensively to study the interactions of the host, the pathogen, and the environmental conditions influencing the outcome of persistent H. pylori infection. Dietary factors in humans are increasingly recognized as being important factors in modulating progression and severity of H. pylori-induced gastric cancer. Studies using rodent models to verify and help explain mechanisms whereby various dietary ingredients impact disease outcome should continue to be extremely productive.

Helicobacter pylori infection in functional dyspepsia

Functional dyspepsia is the most common reason for patients to experience chronic epigastric pain or discomfort. The causes of functional dyspepsia are multifactorial but Helicobacter pylori infection is one likely candidate. Infection with this bacterial pathogen clearly results in chronic mucosal inflammation in the stomach and duodenum, which, in turn, might lead to abnormalities in gastroduodenal motility and sensitivity. Chronic gastritis might also affect a variety of endocrine functions of the stomach including the production of the gastrointestinal hormones and neurotransmitters somatostatin, gastrin and ghrelin. Although these abnormalities might generate symptoms in some patients with functional dyspepsia, the clinical evidence needs to be critically evaluated before this hypothesis can be confirmed. A Cochrane review reported that eradication of H. pylori in these patients had a small but statistically significant long-term effect on symptom relief when compared with placebo, lasting at least 12 months after 1 week of eradication therapy. The efficacy of eradication therapy was seen in all symptom subtypes of functional dyspepsia, but was more marked in Asian than Western patients. This evidence has led to alterations in most of the major guidelines throughout the world, which now recommend H. pylori eradication in patients with functional dyspepsia if they test positive for this bacterium.

Role of gastrin-peptides in Barrett's and colorectal carcinogenesis

Gastrin is the main hormone responsible for the stimulation of gastric acid secretion; in addition, gastrin and its derivatives exert proliferative and antiapoptotic effects on several cell types. Gastrin synthesis and secretion are increased in certain situations, for example, when proton pump inhibitors are used. The impact of sustained hypergastrinemia is currently being investigated. In vitro experiments and animal models have shown that prolonged hypergastrinemia may be related with higher cancer rates; although, this relationship is less clear in human beings. Higher gastrin levels have been shown to cause hyperplasia of several cell types; yet, the risk for developing cancer seems to be the same in normo- and hypergastrinemic patients. Some tumors also produce their own gastrin, which can act in an autocrine manner promoting tumor growth. Certain cancers are extremely dependent on gastrin to proliferate. Initial research focused only on the effects of amidated gastrins, but there has been an interest in intermediates of gastrin in the last few decades. These intermediates aren’t biologically inactive; in fact, they may exert greater effects on proliferation and apoptosis than the completely processed forms. In certain gastrin overproduction states, they are the most abundant gastrin peptides secreted. The purpose of this review is to examine the gastrin biosynthesis process and to summarize the results from different studies evaluating the production, levels, and effects of the main forms of gastrin in different overexpression states and their possible relationship with Barrett’s and colorectal carcinogenesis.

Infectious causes of colorectal cancer

Colorectal cancer is a major cause of cancer-related morbidity and mortality in the United States and many other regions of the world. Our understanding of the pathogenesis of colorectal cancer, from the precursor adenomatous polyp to adenocarcinoma, has evolved rapidly. Colorectal carcinogenesis is a sequential process characterized by the accumulation of multiple genetic and molecular alterations in colonic epithelial cells. However, the development of colorectal cancer involves more then just a genetic predisposition. External or environmental factors presumably play a significant role, and inflammatory bowel diseases, obesity, alcohol consumption, and a diet high in fat and low in fiber have all been implicated as risk factors for the development of either colonic adenomas or carcinomas. We are becoming increasingly aware of microbes as causes of malignancies. This article reviews the various microbes that have been associated with the development of colorectal carcinomas.

Combination of sulindac and antimicrobial eradication of Helicobacter pylori prevents progression of gastric cancer in hypergastrinemic INS-GAS mice

Helicobacter pylori infection causes severe dysplasia manifested as gastrointestinal intraepithelial neoplasia (GIN) after 28 weeks post-H. pylori infection (WPI) in cancer-prone, hypergastrinemic male INS-GAS mice. We examined the efficacy of the nonsteroidal anti-inflammatory drug sulindac (400 ppm in drinking water) alone, the CCK2/gastrin receptor antagonist YM022 (45 mg/kg/wk) alone, and sulindac or YM022 combined with H. pylori eradication therapy to prevent H. pylori-associated gastric cancer in male INS-GAS mice. Treatments started at 22 WPI, and mice were euthanized at 28 WPI. In uninfected mice, all treatments significantly delayed development of spontaneous GIN (P < 0.05). In H. pylori-infected mice, sulindac alone or YM022 alone had no protective effect on H. pylori-associated GIN. Importantly, sulindac exacerbated the severity of H. pylori-associated gastritis despite decreased gastric prostaglandin E(2) levels. However, sulindac combined with H. pylori antimicrobial eradication reduced the incidence of GIN (P < 0.05), whereas YM022 combined with antimicrobial eradication did not reduce GIN. In infected mice, sulindac or YM022 treatment did not alter gastric expression of the proinflammatory cytokines Ifn-gamma and Tnf-alpha and mucosal cell proliferation. Sulindac or YM022 combined with antimicrobial eradication down-regulated mRNA levels of Ifn-gamma and Tnf-alpha and mucosal cell proliferation (P < 0.05). We conclude that sulindac enhances H. pylori gastritis and may promote inflammation-mediated gastric carcinogenesis. The combination of sulindac and antimicrobial H. pylori eradication was beneficial for reducing proinflammatory cytokine mRNA in the stomach and preventing progression from severe dysplasia to gastric cancer in H. pylori-infected INS-GAS mice.

Infectious agents and colorectal cancer: a review of Helicobacter pylori, Streptococcus bovis, JC virus, and human papillomavirus

Based on the high volume of bacteria and viruses that the intestine is exposed to and the importance of infectious agents in some gastrointestinal and anogenital cancers, it is not surprising the many studies have evaluated the association between colorectal cancer and infectious agents. This review highlights investigations of four agents in relation to colorectal cancer. Helicobacter pylori, Streptococcus bovis, JC virus, and human papillomavirus have all been evaluated as possible etiologic agents for colorectal cancer. For each of these agents, a review of possible mechanisms for carcinogenesis and epidemiologic evidence is discussed, and future directions for research are proposed.

Helicobacter pylori infection and short-term intake of low-dose aspirin have different effects on alpha-1 antitrypsin/alpha-1 peptidase inhibitor (alpha1-PI) levels in antral mucosa and peripheral blood

OBJECTIVE

Alpha-1 protease inhibitor (alpha1-PI) is the major circulating serine protease inhibitor. The purpose of the study was to investigate alpha1-PI expression in gastroduodenal mucosa and blood with respect to two major etiological risk factors for gastroduodenal diseases, Helicobacter pylori infection and intake of low-dose aspirin.

MATERIAL AND METHODS

Twenty volunteers (H. pylori-positive and -negative: n=10) received 2 x 50 mg aspirin/day for 7 days. H. pylori-positive subjects underwent eradication therapy and repeated the protocol. Blood and tissue samples were obtained on days 0, 1, 3 and 7; alpha1-PI levels were determined by enzyme-linked immunosorbent assay (ELISA) and quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) and analyzed for histopathological findings.

RESULTS

Mucosal alpha1-PI expression was between 30 and 75 pg/10 microg total protein in H. pylori-negative subjects, and found to be similar in antral, corpus and duodenal mucosa. In H. pylori-infected subjects, alpha1-PI levels were significantly increased in the antrum (mean: 111 versus 37.4 pg/10 microg protein; p=0.019), whereas corresponding levels in the corpus, duodenum and sera were unchanged. Alpha-1-PI transcript levels were similarly induced in H. pylori-infected subjects (0.13+/-0.15 versus 0.027+/-0.043 a.u. (arbitrary units), p=0.018). Immunohistochemistry demonstrated that infiltrating immune cells and antral surface epithelium contributed to elevated alpha1-PI expression in H. pylori-infected subjects. The concomitant use of low-dose aspirin did not change mucosal alpha1-PI levels, but led to a 2-fold increase in alpha1-PI levels in sera independently of the H. pylori status (p<0.009).

CONCLUSIONS

Antral alpha1-PI expression is specifically induced by H. pylori infection, suggesting a pathophysiological role of this protease inhibitor in the upper gastrointestinal tract, whereas low-dose aspirin led to an increase in systemic alpha1-PI levels.

Circulating markers for endocrine tumours of the gastroenteropancreatic tract

The diffuse endocrine system (DES) includes a wide range of secretory cells that may be the source of tumours. Gastroenteropancreatic endocrine (GEP) tumours arising within the DES secrete a variety of peptides and amines that are found in the circulation and are responsible for the syndromes associated with these tumours. In this review, the most common tumours of the GEP tract are outlined and the circulating products of these tumours identified. Where differential diagnosis is difficult these points are addressed. The peptides most commonly secreted by GEP neuroendocrine tumours are identified and described and their biological activities are discussed. Current methods available for measurement of these peptides are described. Attention is drawn towards molecular specificity where appropriate, as many pancreatic and gut peptides fall within families which show considerable homology, such as the tachykinin family or the glucagon family. Other peptides such as gastrin circulate in multiple molecular forms. This homology and diversity may cause difficulty in the interpretation of peptide measurements in the clinical situation if assays are not specific.

Barrett's esophagus is characterized by the absence of Helicobacter pylori infection and high levels of serum pepsinogen I concentration in Japan

BACKGROUND AND AIM

It has been reported that patients with Barrett's esophagus (BE) may have gastric acid hypersecretion. Serological markers such as serum pepsinogen or gastrin have been used to estimate the gastric secretory function. The aim of this study was to compare the serum pepsinogen and gastrin concentrations in view of Helicobacter pylori infection status between BE patients and the controls.

METHODS

Thirty-six patients with long-segment BE were enrolled in this study. Three age- and sex-matched controls were assigned to each patient. Serum pepsinogen and gastrin concentrations were measured by radioimmunoassay and H. pylori infection was determined by histology and serum IgG antibodies.

RESULTS

Helicobacter pylori infection was present in 4 of 36 patients (11%) with BE and in 80 of 108 controls (74%), being less prevalent in BE patients than in the controls (P < 0.0001). When examined in the H. pylori-negative subjects, both the serum pepsinogen I and pepsinogen II concentrations in BE patients were significantly higher than those in the controls (mean pepsinogen I:BE 51.0 +/- 14.0 ng/mL vs control 38.9 +/- 13.5 ng/mL, P = 0.0012; mean pepsinogen II:BE 10.8 +/- 4.0 ng/mL vs control 7.9 +/- 2.0 ng/mL, P = 0.0097). There was no significant difference in the serum gastrin levels between BE patients and the controls irrespective of the H. pylori infection status.

CONCLUSIONS

Most of the Japanese BE patients are characterized by the absence of H. pylori infection and high levels of serum pepsinogen. Determination of the serum pepsinogen level in combination with the H. pylori infection status could be a useful serological marker for BE screening.

The role of serum pepsinogen and gastrin test for the detection of gastric cancer in Korea

BACKGROUND AND AIM

This study was performed to determine whether serum pepsinogen (PG) and gastrin testing can be used to detect gastric cancer in Korea.

METHODS

Serum levels of PG I (sPGI) and sPGII, PG I/II ratios, and gastrin levels were measured in 1006 patients with gastroduodenal diseases including cancer. Follow-up tests were performed 1 year after Helicobacter pylori eradication.

RESULTS

sPGI and sPGII levels increased and PG I/II ratios decreased in line with the severity of activity, chronic inflammation, and the presence of H. pylori (p < .01). In contrast, sPGI levels and PG I/II ratios decreased in proportion with the severity of atrophic gastritis (AG)/intestinal metaplasia (p < .01). Gastrin levels were found to be correlated with chronic inflammation negatively in the antrum but positively in the corpus. H. pylori eradication reduced sPGI, sPGII, and gastrin levels, and increased PG I/II ratios to the levels of H. pylori-negative patients, and was found to be correlated with reductions in activity and chronic inflammation of gastritis. The sensitivity and specificity of a PG I/II ratio of < or = 3.0 for the detection of dysplasia or cancer were 55.8-62.3% and 61%, respectively. In addition, sPGI and sPGII levels of intestinal-type cancer were significantly lower than those of the diffuse type, respectively (p = .008 and p = .05, respectively). Gastric cancer risk was highest in the H. pylori-positive, low PGI/II ratio (< or = 3.0) group with an odds ratio of 5.52 (confidence interval: 2.83-10.77).

CONCLUSION

PG I/II ratio (< or = 3.0) was found to be a reliable marker for the detection of dysplasia or gastric cancer, especially of the intestinal type. This detection power of PG I/II ratio (< or = 3.0) significantly increased in the presence of H. pylori, and thus, provides a means of selecting those at high risk of developing gastric cancer in Korea.

Two distinct aetiologies of cardia cancer; evidence from premorbid serological markers of gastric atrophy and Helicobacter pylori status

BACKGROUND

Non-cardia gastric adenocarcinoma is positively associated with Helicobacter pylori infection and atrophic gastritis. The role of H pylori infection and atrophic gastritis in cardia cancer is unclear.

AIM

To compare cardia versus non-cardia cancer with respect to the premorbid state of the stomach.

METHODS

Nested case-control study. To each of 129 non-cardia and 44 cardia cancers, three controls were matched. Serum collected a median of 11.9 years before the diagnosis of cancer was tested for anti-H pylori antibodies, pepsinogen I:II and gastrin.

RESULTS

Non-cardia cancer was positively associated with H pylori (OR 4.75, 95% CI 2.56 to 8.81) and gastric atrophy (pepsinogen I:II <2.5; OR 4.47, 95% CI 2.71 to 7.37). The diffuse and intestinal histological subtypes of non-cardia cancer were of similar proportions and both showed a positive association with H pylori and atrophy. Cardia cancer was negatively associated with H pylori (OR 0.27, 95% CI 0.12 to 0.59), but H pylori-positive cardia cancer showed an association with gastric atrophy (OR 3.33, 95% CI 1.06 to 10.5). The predominant histological subtype of cardia cancer was intestinal and was not associated with gastric atrophy compared with the diffuse subtype ((OR 0.72, 95% CI 0.19 to 2.79) vs (OR 3.46, 95% CI 0.32 to 37.5)). Cardia cancer in patients with atrophy had an intestinal: diffuse ratio (1:1) similar to non-cardia cancer (1.9:1), whereas cardia cancers in patients without atrophy were predominantly intestinal (7:1).

CONCLUSION

These findings indicate two aetiologies of cardia cancer, one associated with H pylori atrophic gastritis, resembling non-cardia cancer, and the other associated with non-atrophic gastric mucosa, resembling oesophageal adenocarcinoma. Serological markers of gastric atrophy may provide the key to determining gastric versus oesophageal origin of cardia cancer.

Gastrin-induced apoptosis contributes to carcinogenesis in the stomach

Hypergastrinemia in INS-GAS mice leads to accelerated carcinogenesis of the stomach, but the mechanisms have not been well defined. We investigated the possible role of gastrin-induced gastric cell apoptosis in the development of gastric cancer. We examined apoptosis and the expression of Bcl-2 family proteins in INS-GAS mice of different ages, as well as in gastrin-deficient (GAS-KO) mice after gastrin-17 (G-17) infusion. In addition, we studied the effects of the gastrin/cholecystokinin-2 (CCK-2) receptor antagonist YF476 and/or histamine H2 (H-2) receptor antagonist loxtidine on apoptosis and atrophy in INS-GAS mice with or without Helicobacter felis (H. felis) infection. INS-GAS mice had age-associated increases in Bax protein expression and decreases in Bcl-2 protein expression, along with increased glandular and epithelial cell apoptosis. At 8-week gastrin infusions in GAS-KO mice resulted in a similar pattern of altered Bax and Bcl-2 expression, followed by gastric cell apoptosis. H. felis infection of INS-GAS mice led to increased apoptosis and the development of atrophy, whereas treatment with either YF476 and/or loxtidine strongly inhibited both apoptosis and atrophy. In vitro studies with Fas-expressing RGM1 cells showed that gastrin stimulation alone directly induced apoptosis via gastrin/CCK-2 receptor and synergized with FasL stimulation. These results indicate that gastrin can induce apoptosis in gastric epithelial cells and contribute to the development of gastric carcinogenesis.

Helicobacter pylori can induce heparin-binding epidermal growth factor expression via gastrin and its receptor

Both gastrin and Helicobacter pylori have been shown capable of up-regulating gene expression and protein shedding of heparin-binding epidermal growth factor (HB-EGF). Furthermore, the bacteria have previously been shown to induce serum hypergastrinemia in infected individuals. The aim of this work was to assess the extent to which the ability of H. pylori to up-regulate expression of HB-EGF can be attributed to its effect on gastrin. Gastric cells, transfected with either gastrin small interfering RNA or antisense plasmid or the gastrin/cholecystokinin-2 receptor (CCK-2R), were cultured for 24 hours with H. pylori(+/-), a CCK-2R antagonist. Gene expression levels were measured using reverse transcription-PCR, whereas protein changes were measured using ELISA, Western blotting, and immunofluorescence. H. pylori induced significantly higher levels of HB-EGF gene expression and ectodomain shedding in the CCK-2R-transfected cells than the vector control (P < 0.01). Addition of the CCK-2R inhibitor significantly decreased gene and shedding up-regulation. Gastrin down-regulation reduced the effect of the bacteria on HB-EGF gene and protein expression levels. Endogenous gastrin and CCK-2R expression were also found to be significantly up-regulated in all cell lines as a result of exposure to H. pylori (P < 0.02). Gastric mucosal tissue from H. pylori-infected individuals had significantly higher CCK-2R expression levels than noninfected (P < 0.003), and in hypergastrinemic mice, there was an increase in HB-EGF-expressing cells in the gastric mucosa and colocalization of HB-EGF with CCK-2R-positive enterochromaffin-like cells. In conclusion, gastrin and the CCK-2R play significant roles in the induction of HB-EGF gene and protein expression and ectodomain shedding by H. pylori.

Molecular biology of Barrett's cancer

Oesophageal adenocarcinoma (OA) remains one of the more deadly forms of gastro-intestinal cancer with a mortality rate exceeding 90%. The incidence of OA remains unabated and has a reported fivefold increase since 1970 [Pera M, Cameron AJ, Trastek VF, Carpenter HA & Zinsmeister AR. Increasing incidence of adenocarcinoma of the esophagus and esophagogastric junction. Gastroenterology 1993; 104(2): 510-513]. Gastro-oesophageal reflux disease and its sequelae, Barrett's oesophagus, is one of the principle risk factors in the development of OA, with a 30-fold increased risk in Barrett's patients compared with the general population [Tytgat GNJ. Does endoscopic surveillance in esophageal columnar metaplasia (Barrett's-Esophagus) have any real value. Endoscopy 1995; 27(1): 19-26]. OA is thought to be a microcosm of evolution, developing sequentially along the metaplasia-dysplasia-adenocarcinoma sequence. Progression is attributed to a series of genetic and epigenetic events that ultimately allow for clonal selection of Barrett's cells via subversion of intrinsic control mechanisms regulating cellular proliferation and/or apoptosis. This review will describe the current suppositions of the mechanisms behind the selection and subsequent expansion of Barrett's clones, and focus on some of the principle hallmarks associated with this transition.

Low circulating levels of gastrin-17 in patients with Barrett's esophagus

AIM: To examine whether the fasting levels of serum gastrin-17 (G-17) are lower in Barrett's esophagus (BE) patients than in non-Barrett controls.

METHODS: Nineteen patients with BE (presenting with a tubular segment ≥2 cm long in lower esophagus and intestinal metaplasia of incomplete type ("pecialized columnar epithelium") in endoscopic biopsies from the tubular segment below the squamocolumnar junction were collected prospectively from outpatients referred to diagnostic gastroscopy. The controls comprised 199 prospectively collected dyspeptic outpatients without BE or any endoscopically visible lesions in the upper GI tract. Fasting levels of serum G-17 (G-17fast) were assayed with an EIA test using a Mab highly specific to amidated G-17. None of the patients and controls received therapy with PPIs or other antisecretory agents.

RESULTS: The mean and median levels of G-17fast in serum were significantly lower (P = 0.001) in BE patients than in controls. The positive likelihood ratios (LR+) of low G-17fast to predict BE in the whole study population at G-17fast levels <0.5, <1, or <1.5 pmol/L were 3.5, 3.0, and 2.8, respectively. Among patients and controls with healthy stomach mucosa, the LR+ were 5.6, 3.8, and 2.6, respectively. In the whole study population, serum G-17 was below 2 pmol/L in 15 of 19 BE patients (79%). The corresponding prevalence was 66 of 199 (33%) in controls (P<0.001). The G-17fast was 5 pmol/L or more in only one of the 19 BE patients (5%). In controls, 76 of the 199 patients (38%) had such high serum G-17fast levels (P<0.01).

CONCLUSION: Serum levels of G-17fast tend to be lower in native patients with BE than in healthy controls.

Histamine-2 receptor expression in gastric mucosa before and after Helicobacter pylori cure

BACKGROUND

Helicobacter pylori infection prevents the occurrence of the tolerance phenomenon of Histamine-2 (H2) receptor antagonists. Gastro-esophageal reflux disease develops in some cases with the restoration of acid secretion after H. pylori eradication therapy.

AIM

To clarify the mechanisms of H2 receptor restoration after the eradication of H. pylori on parietal cells.

METHODS

We enrolled 80 consecutive asymptomatic male patients with H. pylori infection, having chronic gastritis with or without the presence of peptic ulcers. Biopsy specimens from the greater curvatures at the mid-corpus of the stomach were obtained endoscopically from all subjects before and 12 weeks after the eradication of H. pylori. Degrees of gastric atrophy were evaluated by serum pepsinogen levels. The amounts of mRNA expression of H2 receptor were evaluated in each subject's gastric mucosa by real time reverse transcriptase-polymerase chain reaction (RT-PCR).

RESULTS

H2 receptor mRNA expression levels significantly correlated with serum pepsinogens I and II ratios. The expression level of H2 receptor mRNA was lower in subjects with hypergastrinemia. The median expression level of H2 receptor after H. pylori eradication was threefold greater than prior to treatment. In addition, its restoration became more pronounced in subjects with severe gastric atrophy. However, a comparatively low restoration of H2 receptor mRNA was found in subjects with hypergastrinemia.

CONCLUSIONS

H2 receptor mRNA levels decrease with the progression of gastric atrophy induced by H. pylori infection, and are restored after H. pylori eradication. Such expression levels of H2 receptor may explain a part of the tolerance phenomenon to H2 receptor antagonists.

Overexpression of glycine-extended gastrin inhibits parietal cell loss and atrophy in the mouse stomach

Recently we have reported synergistic effects between glycine-extended gastrin (G-gly) and amidated gastrin-17 on acid secretion in short-term infusion studies. In the present study, we examined the long-term effect of G-gly on the atrophy-promoting effects of amidated gastrin in the mouse stomach with or without Helicobacter infection. Transgenic mice overexpressing amidated gastrin (INS-GAS mice), G-gly (MTI/G-gly mice), and both peptides (INS-GAS/G-gly mice) were used for assessment of acid secretion and ulcer susceptibility and histologic examination and scoring of preneoplastic lesions in response to the 3 and 6 months Helicobacter felis (H. felis) infection. We found that MTI/G-gly mice had normal gastric histology and acid secretion. Double transgenic (INS-GAS/G-gly) mice showed 2-fold increases in acid secretion compared with INS-GAS mice. Acute peptic ulcers after pyloric ligation were noted in 50% of the INS-GAS/G-gly mice but in none of the INS-GAS mice at 6 months of age. Whereas male INS-GAS mice had a >50% decrease in the numbers of parietal cell and enterochromaffin-like cell at 6 months of age, the male double transgenic mice had no such decrease. Overexpression of G-gly reduced the scores of preneoplasia in the stomach; however, it did not prevent the development of amidated gastrin-dependent gastric cancer in both H. felis-infected mice and uninfected mice. We conclude that G-gly synergizes with amidated gastrin to stimulate acid secretion and inhibits parietal cell loss in INS-GAS/G-gly mice. The overexpression of G-gly seems to increase the susceptibility to peptic ulcer disease and delay the development of Helicobacter-mediated gastric preneoplasia in this model.

Intact gram-negative Helicobacter pylori, Helicobacter felis, and Helicobacter hepaticus bacteria activate innate immunity via toll-like receptor 2 but not toll-like receptor 4

Molecular and genetic studies have demonstrated that members of the Toll-like receptor (TLR) family are critical innate immune receptors. TLRs are recognition receptors for a diverse group of microbial ligands including bacteria, fungi, and viruses. This study demonstrates that distinct TLRs are responsible for the recognition of Helicobacter lipopolysaccharide (LPS) versus intact Helicobacter bacteria. We show that the cytokine-inducing activity of Helicobacter LPS was mediated by TLR4; i.e., TLR4-deficient macrophages were unresponsive to Helicobacter pylori LPS. Surprisingly, the cytokine response to whole Helicobacter bacteria (H. pylori, H. hepaticus, and H. felis) was mediated not by TLR4 but rather by TLR2. Studies of HEK293 transfectants revealed that expression of human TLR2 was sufficient to confer responsiveness to intact Helicobacter bacteria, but TLR4 transfection was not sufficient. Our studies further suggest that cag pathogenicity island genes may modulate the TLR2 agonist activity of H. pylori as cagA+ bacteria were more active on a per-cell basis compared to cagA mutant bacteria for interleukin-8 (IL-8) cytokine secretion. Consistent with the transfection studies, analysis of knockout mice demonstrated that TLR2 was required for the cytokine response to intact Helicobacter bacteria. Macrophages from both wild-type and TLR4-deficient mice produced a robust cytokine secretion response (IL-6 and MCP-1) when stimulated with intact Helicobacter bacteria. In contrast, macrophages from TLR2-deficient mice were profoundly unresponsive to intact Helicobacter stimulation, failing to secrete cytokines even at high (100:1) bacterium-to-macrophage ratios. Our studies suggest that TLR2 may be the dominant innate immune receptor for recognition of gastrointestinal Helicobacter species.

Serological markers for gastric atrophy in asymptomatic patients infected with Helicobacter pylori

OBJECTIVE

Atrophic gastritis is a precancerous condition that is commonly caused by chronic Helicobacter pylori (H. pylori) infection. This blinded, controlled study was designed to determine if serum gastrin and pepsinogens were reliable markers of atrophy in asymptomatic patients.

METHODS

One hundred and forty-seven asymptomatic patients underwent endoscopy with multiple gastric biopsies obtained for histology, culture, and rapid urease test. Fasting serum gastrin (total and G-17) and serum pepsinogens (I-II) were determined by standard immunoassays. Gastric atrophy was histologically assessed in accordance with internationally accepted criteria; three main patterns of gastritis were distinguished: (a) nonatrophic gastritis, (b) atrophic antrum-restricted and antrum-predominant gastritis, and (c) corpus-restricted gastritis. Receiving operating characteristic (ROC) analysis was used to determine the best cut-off for each serum test in nonatrophic gastritis versus antrum-restricted/antrum-predominant atrophic gastritis.

RESULTS

No significant differences in serum gastrin and pepsinogens I-II were detected in nonatrophic gastritis versus patients with antrum-restricted/antrum-predominant atrophic gastritis. The positive likelihood ratios for an abnormal serum test to detect antrum-restricted/antrum-predominant atrophy in the gastric body were total serum gastrin 2.13 (95% CI 0.99, 4.6), gastrin-17: 1.55 (95% CI 0.75, 36.17), pepsinogen I: 2.74 (1.4, 5.4), pepsinogen II: 1.74 (1.27, 2.39), and the ratio of pepsinogen I and II: 1.8 (1.2-2.8). Negative likelihood ratios ranged from 0.20 to 0.65.

CONCLUSION

In an asymptomatic population, serum gastrin (total and G-17) and pepsinogens I-II (and their ratio) do not discriminate nonatrophic versus antrum-restricted/predominant atrophic gastritis.

Effects of Helicobacter pylori infection on the link between regenerating gene expression and serum gastrin levels in Mongolian gerbils

Although regenerating gene (Reg) protein is reported to have a trophic effect on gastric epithelial cells, its involvement in human gastric diseases is not clear. We have recently shown that both gastrin and gastric mucosal inflammation enhance Reg gene expression in the fundic mucosa in rats. This study was designed to clarify whether Reg protein is involved in Helicobacter pylori-induced gastritis and whether Reg gene expression is linked to serum gastrin levels in this condition. Mongolian gerbils were inoculated with an H. pylori strain isolated from a gastric cancer patient. Four weeks later, some of the gerbils with H. pylori infection were eradicated by lansoprazole, amoxicillin, and clarithromycin. The time courses of changes in Reg gene expression, serum gastrin levels, gastric acidity, and histopathologic factors were examined. Four weeks after H. pylori infection, gastritis started spreading to the fundic mucosa, and gastric acidity started reducing. Serum gastrin levels and Reg mRNA expression in the fundus were significantly increased 6 weeks after infection. Reg mRNA expression in the fundus correlated significantly with both serum gastrin levels and the severity of fundic mucosal inflammation. After H. pylori eradication, serum gastrin levels and fundic mucosal inflammation were normalized, and the increase in Reg mRNA expression was abolished. The Reg gene is associated with hypergastrinemia and fundic mucosal inflammation and may be involved in H. pylori-induced gastritis.

Pathophysiology of gastric acid secretion in patients with chronic renal failure: influence of Helicobacter pylori infection

OBJECTIVES

The incidence of gastroduodenal diseases is high in patients with chronic renal failure (CRF). However, gastric acidity in CRF has been reported to range in level from low to high. Moreover, it remains unknown whether Helicobacter pylori infection influences gastric acidity in such patients. Thus, we aimed to clarify the pathophysiological perturbation in gastric acidity and to determine the influence of H. pylori infection in CRF.

DESIGN

Case-control study.

SETTING

A university hospital.

SUBJECTS

Twenty-seven patients with CRF and 24 control patients, presenting with either gastrointestinal symptoms, positive faecal occult blood, or anaemia (haemoglobin <10 g dL(-1)).

MEASURES

The patients underwent gastroduodenal endoscopy with simultaneous determination of H. pylori infection. Gastric ammonium concentration, serum pepsinogen I and II, and basal gastrin level were measured. Thereafter, gastric acid secretion was monitored by 24-h intragastric acidity measurement with calculation of pH-3 holding time (%) (hours showing pH>3/24 h).

RESULTS

In the CRF group, pH-3 holding time of H. pylori (+) subgroup was significantly greater than that of H. pylori (-) subgroup (71.2 +/- 32.4% vs. 32.8 +/- 30.0%, mean +/- SD; P=0.03). Pepsinogen I/II ratio was inversely correlated with pH-3 holding time in the control and CRF groups. Gastric ammonium concentration in CRF/H. pylori (+) subgroup (14.1 +/- 9.2 mmol L(-1)) was significantly higher than in CRF/H. pylori (-) (2.5 +/- 2.7 mmol L(-1); P=0.002) and control/H. pylori (+) subgroups (6.1 +/- 4.2 mmol L(-1); P=0.01). Serum gastrin level was significantly higher in the CRF group than in the control group (297 +/-343 pg mL(-1) vs. 116 +/- 69 pg mL(-1); P=0.02) as a whole. However, there was no significant correlation between serum creatinine and gastrin levels in the CRF group. Gastrin level in CRF/H. pylori (+) subgroup was significantly higher than in CRF/H. pylori (-), control/H. pylori (+), and control/H. pylori (-) subgroups (423 +/-398 pg mL(-1) vs. 113 +/- 79, 124 +/- 78, and 96 +/-43 pg mL(-1), respectively; P=0.01-0.03). Significant positive correlations amongst pH-3 holding time, ammonium and gastrin concentrations were found in the CRF group, but not in the control group.

CONCLUSIONS

CRF without H. pylori infection primarily shows a tendency for high gastric acidity, but without hypergastrinaemia. Persistent H. pylori infection in CRF leads to decreased acidity and, consequently, to fasting hypergastrinaemia via a feedback mechanism. The hypoacidity in CRF with H. pylori infection appears to result from neutralization of acid by ammonia as well as from gastric atrophy. Thus, H. pylori infection status critically determines perturbation in gastric acidity and fasting gastrin level in CRF.

Comparison of the effects of rebamipide with those of cimetidine on chronic gastritis associated with Helicobacter pylori in Mongolian gerbils

BACKGROUND AND AIMS

The effects of rebamipide on chronic gastritis associated with Helicobacter pylori have not been well-defined. We compared these effects of rebamipide with those of cimetidine in Mongolian gerbils infected with H. pylori.

METHODS

Mongolian gerbils with or without H. pylori were divided into 10 groups 6 weeks after inoculation and fed diets containing a drug (rebamipide or cimetidine) or control diet. All animals were sacrificed 4 weeks after grouping. Their stomachs were examined for histology, colonization by H. pylori, myeloperoxidase activity (myeloperoxidase), production of neutrophil chemokine (CINC/KC) and tumour necrosis factor-alpha (TNF-alpha), and serum gastrin levels.

RESULTS

H. pylori colonized all of the inoculated animals. Neither rebamipide nor cimetidine decreased myeloperoxidase activity, but each reduced wet stomach weight in H. pylori-infected animals. The amount of increase in CINC/KC and TNF-alpha in gastric tissue caused by H. pylori infection was decreased by treatment with rebamipide or cimetidine. H. pylori infection increased serum gastrin levels, and this increase was significantly enhanced by cimetidine but not rebamipide.

CONCLUSIONS

Rebamipide may improve H. pylori-infected chronic gastritis by preventing the production of inflammatory cytokines and chemokines, as does cimetidine, but may be preferable to cimetidine for long-term administration for treatment of H. pylori-infected chronic gastritis due to its effect on serum gastrin levels.

Gastrin activates nuclear factor kappaB (NFkappaB) through a protein kinase C dependent pathway involving NFkappaB inducing kinase, inhibitor kappaB (IkappaB) kinase, and tumour necrosis factor receptor associated factor 6 (TRAF6) in MKN-28 cells transfected with gastrin receptor

BACKGROUND

We previously reported that gastrin induces expression of CXC chemokines through activation of nuclear factor kappaB (NFkappaB) in gastric epithelial cells that express gastrin receptor.

AIMS

To clarify gastrin receptor mediated signals leading to activation of NFkappaB.

METHODS

MKGR26 cells were created by transfecting gastrin receptor cDNA into MKN-28 cells. Degradation of inhibitor kappaB (IkappaB) and phosphorylation of protein kinase C (PKC)-delta were both detected by western blot analysis. NFkappaB activation was determined by luciferase assay and electrophoretic mobility shift analysis.

RESULTS

Gastrin induced degradation of IkappaB-alpha and activation of NFkappaB, which was abolished by the selective gastrin receptor antagonist L-740,093 and the general PKC inhibitor GF109203X. Gastrin induced phosphorylation of PKC-delta, and its inhibitor rottlerin partially suppressed NFkappaB activation. However, the mitogen activated protein kinase (MAPK) kinase inhibitor PD98059, p38 MAPK inhibitor SB203580, and tyrphostin AG1478 had no effect on NFkappaB activation. Introduction of the dominant negative mutant of IkappaB kinase, of NFkappaB inducing kinase, and of tumour necrosis factor receptor associated factor 6 (TRAF6), but not that of TRAF2, inhibited gastrin induced activation of NFkappaB.

CONCLUSIONS

Gastrin activates NFkappaB via a PKC dependent pathway which involves IkappaB kinase, NFkappaB inducing kinase, and TRAF6.

Long-term Treatment with Sterigmatocystin, a Fungus Toxin, Enhances the Development of Intestinal Metaplasia of Gastric Mucosa in Helicobacter pylori-infected Mongolian Gerbils

BACKGROUND

Helicobacter pylori is a human gastric carcinogen. Sterigmatocystin (ST), a fungus toxin, is a risk factor of gastric cancer. Cytotoxin-vacuolation toxin A (VacA) present in supernatants of H. pylori suspensions can cause gastritis and ulcer. The aim of this study was to examine the effects of H. pylori, ST and VacA in Mongolian gerbils.

METHODS

Male Mongolian gerbils (n = 196) were treated with H. pylori supernatants (10 ml/1000 mg) mixed with diet or inoculated intragastrically with H. pylori alone or with ST (100 or 1000 ppb), and then killed 27 months later. Gastric tissue sections were stained with haematoxylin and eosin (H&E), periodic acid-Schiff (PAS), Alcian blue (AB, pH 2.5) and with immunostaining for PCNA and p53 expression.

RESULTS

In H. pylori-infected gerbils, the normal mucosa was replaced by hyperplastic epithelium. Severe gastritis, cystic dilatation of gastric glands, hyperplastic polyps and intestinal metaplasia were observed. In H. pylori + ST (1000 ppb) gerbils, intestinal metaplasia was significantly more frequent than in H. pylori alone animals. No pathological changes were observed in the H. pylori supernatant group. Osseous metaplasia was observed in the H. pylori + ST (100 ppb) group. Serum gastrin levels of the H. pylori + ST (1000 ppb) group were significantly higher than those of the other groups. PCNA labelling index and p53 index of infected gerbils were significantly higher than those of uninfected groups.

CONCLUSION

H. pylori causes gastritis, ulcer and intestinal metaplasia. ST enhances the development of intestinal metaplasia and increases gastrin levels in H. pylori-infected Mongolian gerbils.

Tumour Necrosis Factor Alpha Antibody Affects Gastrin Release in Crohn Disease

BACKGROUND

Gastrin plays an important role in the regulation of gastric acid secretion in humans. Tumour necrosis factor alpha (TNF-α) stimulates gastrin release from antral G cells in vitro. The aim was to determine whether gastrin release decreases in patients with Crohn disease treated with monoclonal antibody to TNF-α.

METHODS

Twenty-five consecutive patients with Crohn disease (10 M, 15 F; 18 with fistulas) were treated with a single intravenous infusion of the monoclonal antibody to TNF-α, infliximab, at a dose of 5 mg/kg. Basal and bombesin stimulated gastrin was measured after an overnight fast immediately before and 2 weeks after infliximab. Helicobacter pylori status was determined by serology.

RESULTS

Twenty-two patients were H. pylori-negative. Basal plasma gastrin was 21 (16-26) pmol/L before and 19 (15-25) pmol/L after infliximab (NS). Bombesin stimulated gastrin decreased from 49 (40-62) pmol/L before to 36 (33-59) pmol/L (P &lt; 0.005) 2 weeks after infliximab.

CONCLUSION

Gastrin release in response to bombesin decreases in patients with Crohn disease treated with infliximab.

Gastrin induces CXC chemokine expression in gastric epithelial cells through activation of NF-kappaB

Although hypergastrinemia is frequently observed in individuals with a chronic Helicobacter pylori infection, its pathophysiological significance in gastric mucosal inflammation is unclear. The present study was designed to determine if gastrin induces the expression of CXC chemokines in gastric epithelial cells. Human and rat gastric epithelial cells, transfected with gastrin receptor, were stimulated with gastrin. The expression of mRNAs for human interleukin-8 (IL-8) and rat cytokine-induced neutrophil chemoattractant-1 and release of human IL-8 protein were then determined by Northern blot analysis and ELISA, respectively. Gastrin not only induced the expression of mRNAs for these chemokines but also stimulated IL-8 protein release. A luciferase assay using IL-8 promoter genes showed that nuclear factor (NF)-kappaB is absolutely required and activator protein-1 (AP-1) is partly required for the maximum induction of IL-8 by gastrin. An electrophoretic mobility shift assay revealed that gastrin is capable of activating both NF-kappaB and AP-1. In addition, the inhibition of NF-kappaB abrogated gastrin-induced chemokine expression. These results suggest that gastrin is capable of upregulating CXC chemokines in gastric epithelial cells and therefore may contribute to the progression of the inflammatory process in the stomach.

Gastric corpus atrophy following eradication of Helicobacter pylori

BACKGROUND

Atrophic gastritis can develop in patients with Helicobacter pylori infection leading to a reduction in basal acid output. Whether the atrophy that develops is reversible is controversial.

OBJECTIVE

To investigate the effect of H. pylori eradication in infected subjects who had developed atrophy of the corpus mucosa.

METHOD

Ten H. pylori positive patients with corpus atrophy were identified at oesophagogastroduodenoscopy (OGD). They received eradication therapy with amoxicillin, clarithromycin and omeprazole. Repeat OGD with biopsy was performed at least 3 months later. Fasting plasma gastrin was measured at baseline and at re-endoscopy. H. pylori eradication was confirmed by 13C urea breath testing.

RESULTS

Median time to re-endoscopy was 5 months. There was improvement in corpus atrophy in 50% of patients after H. pylori eradication, and a significant reduction in plasma gastrin (P = 0.03). The index patients had a significant diminution of basal acid output compared to controls.

CONCLUSION

Corpus atrophy as defined by the Sydney System is reversible in some patients after H. pylori eradication. Improvement in atrophy is associated with a fall in fasting plasma gastrin levels. This may have implications in the prevention of gastric carcinoma.

Circulating cytokines and gastrin levels in asymptomatic subjects infected by Helicobacter pylori (H. pylori)

The pathophysiology of hypergastrinemia in H. pylori infection has been largely investigated and different reports clearly show that the infected antrum has a marked inflammatory response with a suggestive local production of cytokines. Notwithstanding, a few data are available on the circulating levels of cytokines and gastrin in the asymptomatic people carrying H. pylori infection. Thus, aim of the study was to evaluate circulating proinflammatory cytokines [Interleukin (IL)-8, Interleukin (IL)-10, Interferon (IFN)-gamma, and Tumor Necrosis Factor (TNF)-alpha] and gastrin levels in H. pylori positive asymptomatic subjects vs. H. pylori negative ones. To this end, thirty healthy volunteers with no digestive symptoms or systemic disease were enrolled and H. pylori infection was identified by a 13C-urea breath test. Plasma levels of gastrin were determined using the RIA kit whereas IL-8, TNF-alpha, IL-10, and IFN-gamma levels in serum were measured with a solid-phase ELISA. Fifteen infected people showed significantly higher gastrin and TNF-alpha levels than uninfected subjects. On the contrary, IL-8 levels were significantly higher in the uninfected subjects than in H. pylori positive ones (P < 0.0422). IFN-gamma and IL-10 circulating levels were not affected by H. pylori presence, being not significantly different in the two groups.

Seroprevalence of Helicobacter pylori in patients with colorectal polyps and colorectal carcinoma

OBJECTIVES

The role of Helicobacter pylori in the pathogenesis of colorectal polyps and colorectal carcinoma is unknown. H. pylori infection causes fasting and meal stimulated hypergastrinemia. Gastrin increases colorectal mucosal proliferation and promotes tumor growth. We performed a prospective study to determine the seroprevalence of H. pylori in patients with colorectal polyps and colorectal carcinoma and in controls.

METHODS

Blood samples were collected from 189 patients with colorectal carcinoma, 57 patients with colorectal polyps, and 179 controls. H. pylori serology was determined by an ELISA assay.

RESULTS

Logistic regression showed no difference in seroprevalence of H. pylori between patients with colorectal cancer and controls (odds ratio, 1.1; 95% confidence interval, 0.7 to 1.8) or between patients with colorectal polyps and controls (odds ratio 1.3; 95% confidence interval, 0.7 to 2.5). Age and sex were not found to be associated with H. pylori infection. Patients in social classes IV and V were 2.3 times more likely to have H. pylori infection than those in social classes I, II, and III (95% confidence interval, 1.3 to 4.2).

CONCLUSIONS

This study shows that there is no increase in the seroprevalence of H. pylori in patients with colorectal polyps or colorectal carcinoma compared with controls. These results do not support the hypothesis that there is a relationship between H. pylori infection and the development of colorectal neoplasia.

Expression of progastrin-derived peptides and somatostatin in fundus and antrum of nonulcer dyspepsia subjects with and without Helicobacter pylori infection

The hypergastrinemia and hyperacidity associated with Helicobacter pylori infection has been explained by either a primary excess of gastrin or a lack of inhibitory influence by somatostatin (SOM). The objective of the present study was to compare the concentrations of fundic and antral SOM- and antral progastrin-derived peptides in nonulcer dyspepsia (NUD) subjects with and without H. pylori infection. Antral and fundic mucosal biopsies were extracted and assayed for SOM and gastrin amide, glycine-extended gastrin (gastrin gly), progastrin, and total gastrin. There was a significant sixfold reduction in antral SOM but no change in fundic SOM content in H. pylori-infected subjects compared to uninfected subjects. Antral gastrin amide concentrations were significantly higher in infected subjects. However, the concentrations of the nonamidated gastrin forms (progastrin and glycine-extended gastrin) were significantly lower in the infected subjects, indicating an increased conversion of the precursor forms of gastrin to amidated gastrin, the type known to stimulate gastric acidity. The present study demonstrates that the elevated gastrin concentrations associated with H. pylori infection may be due to a reduction in the paracrine inhibitory effect of SOM on antral gastrin release. In addition, the posttranslational processing of gastrin to the amidated forms is increased in infected subjects, explaining why the elevation in antral gastrin is confined to the amidated form.

Helicobacter pylori gastritis and gastric physiology

It is now recognized that Helicobacter pylori infection exerts profound and diverse effects on gastric acid secretory function and that the alterations in acid secretion depend on the pattern of gastritis caused by the infection. In patients with an antral predominant nonatrophic gastritis, there is acid hypersecretion leading to duodenal ulcer disease. In patients with an atrophic pangastritis, there is markedly reduced acid secretion and increased risk for gastric cancer. It is now recognized that acid secretion also modifies H. pylori gastritis and a person's premorbid acid secretory status may be an important factor in determining the pattern of gastritis that an individual develops. This two-way interaction between H. pylori gastritis and gastric acid secretion is important in understanding the role of H. pylori infection in the response to proton-pump inhibitor therapy: It explains the more profound control of gastric acid secretion in H. pylori-positive patients and why rebound acid hypersecretion is confined to H. pylori-negative subjects.

The role of gastrin in ulcer pathogenesis

Duodenal ulcer patients are characterized by an antrum-predominant, body-sparing, nonatrophic Helicobacter pylori (H. pylori) gastritis, which results in increased gastrin release and increased acid secretion. The increased gastrin release is caused by the infection impairing the acid-mediated inhibitory control of gastrin release. The elevated levels of the gastrin stimulate the healthy uninflamed, non-atrophic acid-secreting region of the stomach to secrete excess amounts of acid. The increased gastrin also exerts trophic effects on the oxyntic mucosa, causing hyperplasia of both the enterochromaffin-like cells and the parietal cells. These trophic changes in the mucosa further enhance its ability to secrete acid. The increased acid secretion results in an increased duodenal acid load, causing gastric metaplasia of the duodenal bulb and eventually the development of ulceration. In H. pylori-infected subjects without duodenal ulceration, a different pattern of gastritis is seen. This includes atrophy of the antrum, which reduces the number of G-cells and thus the degree of hypergastrinaemia induced by the antral infection. There are usually also varying degrees of inflammation and atrophy of the acid-secreting mucosa, which impair its ability to secrete acid in response to gastrin stimulation. The combined effects of the atrophy of the antrum and the inflammation of the antrum of the body mucosa therefore prevent H. pylori-induced acid hypersecretion and may result in varying degrees of hypochlorhydria. The particular pattern of gastritis that a subject develops in response to H. pylori infection and their likelihood of developing a duodenal ulcer is likely to be determinded by host genetic factors plus dietary factors.

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

BACKGROUND & AIMS

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.

METHODS

The effects of hypergastrinemia, and possible synergy with Helicobacter felis infection, were investigated in insulin-gastrin (INS-GAS) transgenic mice.

RESULTS

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).

CONCLUSIONS

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.

Helicobacter pylori and gastroesophageal reflux disease

The nature of the relationship between Helicobacter pylori (Hp) infection and gastroesophageal reflux disease (GERD) remains unclear. This article reviews the current body of knowledge regarding the association between these two common entities. The authors examine the potential interactions of Hp and GERD from epidemiologic and pathophysiologic viewpoints and summarize and critique the prevalence and eradication studies that have been performed to date. Special consideration is given to the possible effects that long-term use of proton pump inhibitors may have on Hp gastritis.

Noninvasive evaluation of Helicobacter pylori therapy: role of fasting or postprandial gastrin, pepsinogen I, pepsinogen II, or serum IgG antibodies

OBJECTIVE

We evaluated the potential value of a change in serum IgG antibodies, fasting or meal-stimulated gastrin levels, and pepsinogen I (PGI) or pepsinogen II (PGII) levels for identifying Helicobacter pylori (H. pylori) status after antibiotic therapy.

METHODS

A total of 32 men and one woman with peptic ulcer disease and documented H. pylori infection were enrolled. Fasting and 30-min postprandial blood samples were obtained at 0, 2, 7, 11, 17, 23, 27, and 39 wk of the study and were analyzed for the factors evaluated.

RESULTS

Treatment was successful in 25 patients and failed in seven. Serum IgG antibodies, meal-stimulated gastrin, and both fasting and meal-stimulated pepsinogen I and II levels fell throughout the study, and pepsinogen I:II ratios increased in those whose infection was cured. The mean levels at wk 0 versus wk 7 were: fasting gastrin (fmol/ml) 12.4 and 11, meal-stimulated gastrin 26.5 and 15.4, PGI (ng/ml) 83.7 and 59, PGII (ng/ml) 24.5 and 13.6, PGI/PGII 3.5 and 4.7, and enzyme-linked immunosorbent assay value 4.8 and 4.55. The sensitivity, specificity, and positive and negative predictive values for the data analyzed using different percent changes (e.g., 80%, 50%, and 20%) were calculated. The specificity and sensitivity remained <80% at all time points.

CONCLUSIONS

Despite a significant fall in serum markers of H. pylori infection in groups of individuals, no marker tested could be used to reliably determine posttherapy H. pylori status for individual patients.

Helicobacter pylori infection potentiates the inhibition of gastric acid secretion by omeprazole

BACKGROUND

Omeprazole has a greater intragastric pH elevating effect in Helicobacter pylori positive than negative subjects. Ammonia production by H pylori has been suggested as a probable mechanism.

AIMS

To assess the effect of H pylori status on gastric acid secretion during omeprazole treatment, and to examine the possible role of ammonia neutralisation of intragastric acid in increased omeprazole efficacy in infected subjects.

METHODS

Twenty H pylori positive and 12 H pylori negative healthy volunteers were examined before and six to eight weeks after commencing omeprazole 40 mg/day. On both occasions plasma gastrin and acid output were measured basally and in response to increasing doses of gastrin 17 (G-17). Gastric juice ammonium concentrations were also measured.

RESULTS

Prior to omeprazole, measurements were similar in the H pylori positive and negative subjects. During omeprazole, median basal intragastric pH was higher in the H pylori positive (7.95) versus negative (3.75) subjects (p<0.002). During omeprazole basal, submaximal (180 pmol/kg/h G-17), and maximal acid outputs (800 pmol/kg/h G-17) were lower in H pylori positive subjects (0.0, 3.6, 6.0 mmol/h respectively) versus negative subjects (0.3, 14.2, 18.6 mmol/h) (p<0.03 for each). This effect was not explained by neutralisation by ammonia.

CONCLUSION

The presence of H pylori infection leads to a more profound suppression of acid secretion during omeprazole treatment. The effect cannot be explained by neutralisation of intragastric acid by bacterial ammonia production and its precise mechanism has to be explained.

Rebound hypersecretion after omeprazole and its relation to on-treatment acid suppression and Helicobacter pylori status

BACKGROUND & AIMS

There have been conflicting reports regarding acid secretion after treatment with omeprazole. This study examined acid secretion after treatment with omeprazole and its relation to Helicobacter pylori status and on-treatment gastric function.

METHODS

Twelve H. pylori-negative and 9 H. pylori-positive subjects were examined before, on, and at day 15 after an 8-week course of 40 mg/day omeprazole. On each occasion, plasma gastrin, intragastric pH, and acid output were measured basally and in response to increasing doses of gastrin 17.

RESULTS

In the H. pylori-negative subjects at day 15 after omeprazole treatment, basal acid output was 82% higher (P < 0.007) and maximal acid output 28% higher (P < 0.003) than before omeprazole. The degree of increase in maximal acid output was related to both on-treatment pH and on-treatment fasting gastrin levels, being 48.0% in subjects with an on-treatment pH of >4 vs. 21. 0% in those with a pH of <4 (P < 0.02) and 49.2% in subjects with an on-treatment gastrin of >25 ng. L-1 vs. 19.8% in those with a fasting gastrin of <25 ng. L-1 (P < 0.006). At day 15 after omeprazole treatment, the H. pylori-positive subjects showed a heterogeneous response with some having increased acid output and others persisting suppression.

CONCLUSIONS

Rebound acid hypersecretion occurs in H. pylori-negative subjects after omeprazole treatment. Its severity is related to the degree of elevation of pH on treatment. Persisting suppression of acid secretion masks the phenomenon in H. pylori-positive subjects.

Eradicating Helicobacter pylori reduces hypergastrinaemia during long-term omeprazole treatment

BACKGROUND

Both proton pump inhibitor drug treatment and Helicobacter pylori infection cause hypergastrinaemia in man.

AIMS

To determine whether eradicating H pylori is a means of reducing hypergastrinaemia during subsequent proton pump inhibitor treatment.

METHODS

Patients with H pylori were randomised to treatment with either anti-H pylori or symptomatic treatment. One month later, all received four weeks treatment with omeprazole 40 mg/day for one month followed by 20 mg/day for six months. Serum gastrin concentrations were measured before and following each treatment.

RESULTS

In the patients randomised to anti-H pylori treatment, eradication of the infection lowered median fasting gastrin by 48% and meal stimulated gastrin by 46%. When gastrin concentrations one month following anti-H pylori/symptomatic treatment were used as baseline, omeprazole treatment produced a similar percentage increase in serum gastrin in the H pylori infected and H pylori eradicated patients. Consequently, in the patients in which H pylori was not eradicated, median fasting gastrin concentration was 38 ng/l (range 26-86) at initial presentation and increased to 64 ng/l (range 29-271) after seven months omeprazole, representing a median increase of 68% (p < 0.005). In contrast, in the patients randomised to H pylori eradication, median fasting gastrin at initial presentation was 54 ng/l (range 17-226) and was unchanged after seven months omeprazole at 38 ng/l (range 17-95).

CONCLUSION

Eradicating H pylori is a means of reducing the rise in gastrin during subsequent long term omeprazole treatment. In view of the potential deleterious effects of hypergastrinaemia it may be appropriate to render patients H pylori negative prior to commencing long-term proton pump inhibitor treatment.

The acid response to gastrin distinguishes duodenal ulcer patients from Helicobacter pylori-infected healthy subjects

BACKGROUND & AIMS

Helicobacter pylori-induced hypergastrinemia is accompanied by increased acid secretion in patients with duodenal ulcer (DU) but not in infected healthy volunteers. The aim of this study was to investigate the mechanism underlying this difference.

METHODS

Thirty-four H. pylori-negative and 20 H. pylori-positive healthy volunteers and 15 H. pylori-positive patients with DU were studied. Maximal acid output and sensitivity to gastrin (gastrin concentration required to achieve 50% maximal acid output) were assessed by examining the dose response to gastrin 17. Inhibitory control was tested by comparing the maximal acid response to cholecystokinin octapeptide with that for gastrin 17.

RESULTS

Sensitivity to gastrin was similar in patients with DU (median, 69.5 ng.L-1; range, 26.2-142) and H. pylori-negative healthy volunteers (median, 82.2 ng.L-1; range, 17.7-410); H. pylori-positive healthy volunteers were less sensitive than either (164.5 ng.L-1; range, 44.8 to > 3360 ng.L-1). Patients with DU had higher maximal acid output (51.2 mmol.h-1; range, 30.8-73.7 mmol.h-1) than either infected healthy volunteers (37.8 mmol.h-1; range, 0.0-65.0 mmol.h-1; P < 0.04) or uninfected healthy volunteers (35.3 mmol.h-1; range, 21.3-67.3 mmol.h-1; P < 0.002). The maximal acid output in both groups of healthy subjects was similar. The proportion of maximal acid output to gastrin 17 achieved by cholecystokinin was similar in patients with DU (36.6%; range, 21.5%-58.2%) and H. pylori-negative healthy volunteers (28.7%; range, 5.9%-85.8%).

CONCLUSIONS

A combination of decreased sensitivity to gastrin in infected healthy volunteers and increased maximal acid secretory capacity in patients with DU underlies their different acid response to H. pylori-induced hypergastrinemia.

How does Helicobacter pylori cause mucosal damage? Its effect on acid and gastrin physiology

Helicobacter pylori infection increases gastric acid secretion in patients with duodenal ulcers but diminishes acid output in patients with gastric cancer and their relatives. Investigation of the basic mechanisms may show how H. pylori causes different diseases in different persons. Infection of the gastric antrum increases gastrin release. Certain cytokines released in H. pylori gastritis, such as tumor necrosis factor alpha and specific products of H. pylori, such as ammonia, release gastrin from G cells and might be responsible. The infection also diminishes mucosal expression of somatostatin. Exposure of canine D cells to tumor necrosis factor alpha in vitro reproduces this effect. These changes in gastrin and somatostatin increase acid secretion and lead to duodenal ulceration. But the acid response depends on the state of the gastric corpus mucosa. The net effect of corpus gastritis is to decrease acid secretion. Specific products of H. pylori inhibit parietal cells. Also, interleukin 1 beta, which is overexpressed in H. pylori gastritis, inhibits both parietal cells and histamine release from enterochromaffin-like cells. H. pylori also promotes gastric atrophy, leading to loss of parietal cells. Factors such as a high-salt diet and a lack of dietary antioxidants, which also increase corpus gastritis and atrophy, may protect against duodenal ulcers by decreasing acid output. However, the resulting increase of intragastric pH may predispose to gastric cancer by allowing other bacteria to persist and produce carcinogens in the stomach.

Changes in gastrin and serum pepsinogens in monitoring of Helicobacter pylori response to therapy

The aims of this study in 50 patients with H. pylori infection and duodenal ulcer were to examine the effect of eradication therapy on the serum levels of gastrin, pepsinogen I, and pepsinogen II and to investigate whether monitoring of the serum changes in these peptides after treatment could predict patient outcome. H. pylori status was assessed at entry and one and six months after therapy by culturing and microscopic analysis of the gastric mucosa and by [14C]urea breath test. Significant decreases were observed in the serum levels of gastrin (-11.4 +/- 3%), pepsinogen I (-28.9 +/- 4%), and pepsinogen II (-40.4 +/- 3%) in the 45 patients whose infection was eradicated, but not in the patients without eradication. Serum values of these peptides were unchanged in an additional group of 10 patients that only received omeprazol, none of whom had H. pylori eradicated. The best cutoff point of the percentage of each peptide to predict patient outcome was 10% for gastrin and pepsinogen I, and 15% for pepsinogen II. A pepsinogen II decrease > 15% resulted in the best marker of H. pylori clearance, accurately identifying patient outcome 86.6% of the time, whereas the diagnostic accuracy of gastrin and pepsinogen I was 61.7% and 76.6%, respectively. Significant correlations were found between the bacterial load assessed by histology with the serum concentrations of pepsinogen I and II and with the urease activity as measured by the amount of 14CO2 excreted. In conclusion, eradication of H. pylori infection is followed by a significant drop in serum levels of gastrin, pepsinogen I, and pepsinogen II. Changes in the latter are the most uniform and may be used as an indirect tool to predict treatment outcome.

The clinical usefulness of serum pepsinogens, specific IgG anti-HP antibodies and gastrin for monitoring Helicobacter pylori treatment in older people

OBJECTIVE

To evaluate the clinical usefulness of Pepsinogen A (PGA) and C (PGC), PGA/PGC ratio, gastrin, and specific IgG anti-HP antibodies (anti-HP Ab) in monitoring the effect of cure for Helicobacter pylori (HP) infection in older people.

DESIGN

We studied the changes in serum parameters (PGA, PGC, PGA/PGC ratio, gastrin and anti-HP Ab) in older patients before and 2 months after stopping therapy for the cure of HP infection.

PATIENTS

Eighty-eight older patients (M = 43, F = 45, mean age = 73.3, range = 60-89) with chronic gastritis (42), gastric ulcer (14) or duodenal ulcer (32) were found HP-positive by histology of gastric antral and body biopsies and the rapid urease test.

INTERVENTIONS

Two different associations of antibiotics and antiulcer drugs (omeprazole, metronidazole, azithromycin, or clarithromycin) for 2-4 weeks.

MEASUREMENTS

At the beginning of the study and 2 months after treatment withdrawal, the subjects were studied by upper G.I. endoscopy with at least two antral and two body gastric biopsies (Giemsa stain and rapid urease test for HP); serum PGA (RIA method, microgram/mL), PGC (RIA method, microgram/mL), PGA/PGC ratio, gastrin (RIA method, picogr/mL), and anti-HP Ab (ELISA method, Biolife, MU/mL) were also determined. Statistical analysis was based on either the Wilcoxon test, for paired data, the chi-square test, the Kruskal Wallis test, or the Mann-Whitney test for unpaired data. The choice of the best cut-off value in the different parameters was performed by receiver operating characteristics curves (ROC) and by Youden index. The correlation between HP density in the gastric mucosa and gastritis activity was verified by Spearman rank correlation test.

RESULTS

After therapy, 56/88 patients proved HP-negative (HP-eradicated: M = 30, F = 26, mean age = 73.0, range = 60-87 years), whereas 32/88 were not cured (HP-persistent: M = 13, F = 19, mean age = 73.0, range = 60-89 years). After therapy, in HP-eradicated cases, a statistically significant change was found in anti-HP Ab (75.23 +/- 8.94 vs 47.32 +/- 5.26, P < .001), PGC (21.58 +/- 1.97 vs 14.34 +/- 1.75, P < .001), and PGA/PGC ratio (8.46 +/- 0.68 vs 11.54 +/- 0.89, P < .001), but not in PGA and gastrin. On the other hand, in HP-persistent cases, anti-HP Ab, PGA, PGC, PGA/ PGC ratio and gastrin did not change after therapy. The sensitivity and specificity were, respectively, 0.62 and 0.56 for anti-HP Ab and 0.75 and 0.56 for the PGA/PGC ratio, which demonstrated the best diagnostic accuracy (68%).

CONCLUSIONS

The eradication of HP from the stomach of older patients induces a rapid and significant decrease in serum levels of IgG anti-HP antibodies and PGC, with an increase in PGA/PGC ratio but not in gastrin. Unchanged serum levels of IgG anti-HP antibodies, PGC, and PGA/PGC ratio 2 months after completing HP eradication therapy are indicative of ongoing HP infection. The PGA/PGC ratio showed the best diagnostic accuracy among serum measures tested.

Helicobacter pylori and ulcerogenesis

The dictum "no acid-no ulcer" had, in the past, summarized the thinking concerning the pathogenesis of peptic ulcer disease. It is now recognized that infection with Helicobacter pylori is the major causal factor leading to both duodenal and gastric ulceration. Infection is associated with many of the acid secretory abnormalities that have traditionally characterized peptic ulcer disease; indeed, acid secretory physiology returns to normal following bacterial eradication. Since not all individuals infected with H. pylori develop ulcers, host susceptibility, bacterial virulence, and/or specific environmental factors must determine the response to infection and the ultimate clinical outcome. The relative importance of these factors and their complex interactions remain to be determined. H. pylori infection produces tissue damage indirectly because the organism does not directly invade gastroduodenal tissue. A variety of bacterial enzymes, toxins, and inflammatory mediators produced in response to bacterial colonization challenge the integrity of host mucosal defenses. In a susceptible host, breached defenses render epithelium more vulnerable to acid injury and ulcer development. Eradication of H. pylori leads to rapid ulcer healing and reversal of tissue injury, thereby obviating ulcer recurrence.

Helicobacter pylori and disturbance of gastric function associated with duodenal ulcer disease and gastric cancer

Helicobacter pylori is now recognized as the major acquired factor in the pathogenesis of duodenal ulcer disease (DU). There is also an association between H. pylori infection and the subsequent development of gastric cancer. The mechanisms by which such infection predisposes the host to these diseases are incompletely understood, but disorders induced by the bacterium in gastric function play a pivotal role. In most patients, H. pylori infection stimulates acid secretion, leading to a predisposition to DU development. However, in some patients, the infection is associated with a significant decrease in acid secretion, a predisposition to gastric cancer. These divergent effects of H. pylori on gastric acid secretion explain the early conflicting reports on changes in acid secretion associated with the infection. The reason why H. pylori infection produces divergent effects on gastric acid secretion is unclear, but may be related to differences in bacterial strains or genetic, dietary or other environmental factors.

Helicobacter pylori and hormones

Helicobacter pylori affects gastric acid secretion via several mechanisms. One of these is by changing gastric regulatory physiology. The infection elevates plasma gastrin levels and decreases gastric mucosal expression of the inhibitory peptide somatostatin. These changes may be due to products of H. pylori itself or inflammatory cytokines released in H. pylori infection: acid secretion is inhibited less by a low intra-gastric pH, infusions of cholecystokinin and gastric distention in infected persons. Eradication of H. pylori rapidly decreases basal acid secretion and gastrin-releasing, peptide-stimulated acid secretion. There are now reports that maximally-stimulated acid secretion, a measure of the parietal cell mass, falls significantly six and 12 months after eradication of H. pylori from duodenal ulcer patients. This might be due to withdrawal of the trophic effect of gastrin. However H. pylori can also decrease gastric acid secretion, both through the mechanisms described in Dr. Cave's paper and by causing gastric mucosal atrophy with loss of parietal cells. The net effect on acid presumably depends on which mechanism predominates. The processes involved may be crucial determinants of clinical outcome. For example, infection with little atrophy and high acid secretion is associated with duodenal ulcers, while infection with atrophy and low acid secretion increases the risk of gastric cancer of the intestinal-type.

Eradication of Helicobacter pylori infection in patients with non-ulcer dyspepsia. Effects on basal and bombesin-stimulated serum gastrin and gastric acid secretion

BACKGROUND

This study evaluates the effect of eradicating Helicobacter pylori on basal and bombesin-stimulated gastric acid secretion and serum gastrin in non-ulcer dyspepsia.

METHODS

Before and 1 month after an attempt to eradicate H. pylori basal and bombesin-stimulated gastric acid outputs were measured in 23 patients. H. pylori was eradicated in 15 patients (group A) but not in the other 8 (group B). Incremental gastric acid output was calculated by subtracting basal from bombesin-stimulated values.

RESULTS

Basal acid output increased significantly (p = 0.01) after therapy in group A (delta 1.6 +/- 0.6 mmol/h) but not in group B (delta 0.2 +/- 0.5 mmol/h). Incremental gastric acid output decreased distinctly (delta-3.9 +/- 1.4 mmol/h) after therapy in group A (p = 0.02) but not in group B (delta-2.2 +/- 1.7 mmol/h). Basal serum gastrin decreased significantly (p < 0.005) after therapy in group A (delta-9 +/- 4 pM) but not in group B (delta-1 +/- 2 pM). Integrated serum gastrin responses to bombesin decreased markedly (p < 0.001) after therapy in group A (delta-5.0 +/- 1.6 nM*60 min) but slightly in group B (delta-0.9 +/- 1.3 nM*60 min) (p < 0.05).

CONCLUSIONS

In patients with non-ulcer dyspepsia basal serum gastrin concentrations decrease but basal gastric acid outputs increase after eradication of H. pylori. Bombesin-induced increments in gastric acid output, however, decrease in parallel with gastrin release.

Helicobacter pylori infection and abnormalities of acid secretion in patients with duodenal ulcer disease

BACKGROUND & AIMS

The mechanism by which Helicobacter pylori predisposes to duodenal ulcers (DUs) remains unclear. The aim of this study was to investigate the effect of the infection on acid secretion.

METHODS

Acid output was examined basally and in response to gastrin-releasing peptide (GRP) and gastrin in healthy volunteers with and without H. pylori infection and in patients with DUs before and after eradication of the infection.

RESULTS

Compared with H. pylori-negative healthy volunteers, patients with DUs with H. pylori had the following abnormalities of acid secretion: (1) threefold increase in basal acid output, (2) sixfold increase in acid response to GRP, (3) increased maximal acid response to exogenous gastrin, (4) increased ratio of basal acid output to maximal gastrin-stimulated output, and (5) increased ratio of maximal GRP-stimulated acid output to maximal gastrin-stimulated output. All of these abnormalities resolved fully after H. pylori eradication except for increased maximal acid output to gastrin, which was unchanged. Infected healthy volunteers showed a threefold increase in acid response to GRP that resolved after eradication of H. pylori infection.

CONCLUSIONS

These disturbances in acid secretion caused by H. pylori infection are consistent with impaired inhibitory control and are likely to be relevant to the mechanism by which the infection predisposes to DU.

Pathogenic mechanisms

Research is asking how H. pylori causes diseases, and also why the same bacteria produces different conditions in different persons. The process involves bacterial factors and the host's response. Some bacterial factors such as urease are produced by all strains of H. pylori. This enzyme may damage the gastric epithelium by practically releasing ammonia. Other bacterial factors such as vacuolating toxin are only produced by some strains, and these strains are more likely to cause ulcers or cancer. The host's response has been studied by physiologists, immunologists, and histologists, but the separation of systems is artificial. For example, physiologists find that H. pylori stops gastric D-cells from expressing somatostatin normally, which impairs reflex inhibition of acid secretion, but the D-cell malfunction is probably due to inflammatory factors. In H. pylori gastritis, the gastric epithelial cells behave like immunocytes and express class II molecules and cytokines such as interleukin-8. The patient's histological response to H. pylori is quite closely related to the disease outcome. Patients who respond by developing gastric atrophy are more likely to get gastric ulcers or stomach cancer, but patients whose gastric corpus remains healthy tend to secrete more acid and develop duodenal ulcers, particularly if they have gastric metaplasia in their duodenum. Studies of disease mechanisms provide a valuable insight into the development of these common diseases, and may enable us to identify at-risk groups who particularly merit eradication therapy.