Helicobacter pylori infection induces hyperammonaemia in Mongolian gerbils with liver cirrhosis

BACKGROUND AND AIMS: We previously reported the effect of Helicobacter pylori eradication on hyperammonaemia in patients with liver cirrhosis. However, the role of H pylori as a cause of hyperammonaemia is controversial. We developed an animal model with liver cirrhosis and investigated the effect of H pylori infection on hyperammonaemia. MATERIALS AND METHODS: Five week old male Mongolian gerbils were inoculated orally with broth culture of H pylori. Forty eight gerbils were divided into four groups. Gerbils not inoculated with H pylori were fed a commercial rodent diet (group A) or a choline deficient diet (group C). Gerbils inoculated with H pylori were fed the commercial rodent diet (group B) or the choline deficient diet (group D). Blood ammonia levels of the femoral vein and portal vein were measured 30 weeks later. RESULTS: All gerbils fed the choline deficient diet developed liver cirrhosis with fatty metamorphosis. The survival rate of group D was significantly lower than that of the other groups. Systemic and portal blood ammonia levels in group D were significantly higher than those in the other groups. CONCLUSIONS: H pylori infection induces hyperammonaemia in gerbils with liver cirrhosis.     

幽门螺杆菌长期感染蒙古沙土鼠腺胃模型的建立及评价

目的 建立幽门螺杆菌（Helicobacter pylori,Hp）长期感染蒙古沙土鼠腺胃模型,验证该模型出现的病理改变及腺胃肿瘤的发生情况。方法 采用国际标准菌株NCTC 11637灌喂蒙古沙土鼠,建立HP长期感染蒙古沙土鼠腺胃模型。结果 成功建立了HP长期感染蒙古沙土鼠腺胃模型,其胃黏膜的组织学变化显示,HP感染可致正常胃黏膜→慢性胃炎→萎缩→肠化生→异型增生的发展过程,Hp NCTC 11637定植于蒙古沙土鼠腺胃65财哩,可引起胃黏膜出现严重的萎缩、肠化生及不典型增生等胃癌前状态,暂未发现早期癌。结论 Hp NCTC 11637易长期定植于蒙古沙土鼠腺胃,模型的稳定性及重复性极佳,且与Hp感染人胃黏膜后出现的各种病理变化极为相似。     

Establishment of Helicobacter pylori infection model in Mongolian gerbils

AIM：To establish a stable and reliable model of Helicobacter pyloriinfection model in Mongolian gerbils and to observe pathological changes in gastric mucosa in infected animals.METHODS:Mongolian gerbils were randomly divided into 18 groups;6 groups were infected with Hpylori clinical strain Y06 (n=6, groups Y), 6 groups were infected with Hpylori strain NCTC11637 (n=6, roups N),and 6 uninfected groups as negative controls (n=4,groups C).Hpylori suspensions at the concentrations of 2×10^8 and 2×10^9CFU/mL of strain NCTC11637 and strain Y06 were prepared. The animals in three groups N and in three groups Y were orally challenged once with 0.5 mL of the low concentration of the bacterial suspension.The animals in another three groups N and in another three groups Y were orally challenged with 0.5mL of the high concentration of the bacterial suspension for 3 times at the intervals of 24 h,respectively.For the negative controls,the animals in six groups C were orally given with the same volume of Brucella broth at the corresponding inoculating time.The animals were killed after 2nd, 4^th and 6^th week after the last challenge and the gastric mucosal specimens were taken for urease test,bacterial isolation, pathological and immunohistochemical examinations.RESULTS:Positive isolation rates of Hpyloriin the animals of groups Y at the 2nd, 4^th and 6^th week after one challenge were 0%, 16.7% and 66.7%, while in the animals of groups N were 0%, 0% and 16.7%, respectively.Positive isolation rates of Hpyloriin the animals of groups Y at the 2nd, 4^th and 6^th week after three challenges were 66.7%,100% and 100%,while in the animals of groups N were 66.7%,66.7% and 100%, respectively. In animals with positive isolation of Hpylori, the bacterium was found to colonized on the surface of gastric mucosal cells and in the gastric pits,and the gastric mucosal lamina propria was infiltrated with inflammatory cells.CONCLUSION:By using H pylori suspension at high concentration of 2×10^9 CFU/mL for multiple times,the orally challenged Mongolian gerbils can be used as a stable and reliable H pylori infection model.The 2 strains of H pylori can colonize in gastric mucosa of the infected animals and cause mild inflammation reaction.     

Helicobacter pylori infection in Mongolian gerbils does not initiate hematological diseases

AIM: To investigate whether Helicobacter pylori (H. pylori) infection contributes to idiopathic thrombocytopenic purpura (ITP) or iron-deficiency anemia (IDA) onset in gerbils.METHODS: A total of 135 Mongolian gerbils were randomly divided into two groups: an H. pylori infection group and a control group. Both groups were fed the same diet and the same amount of food. Each group was then divided into three subgroups, which were sacrificed at 6, 12, or 18 mo for analysis. At each time point, arterial blood was collected from the abdominal aorta and a complete blood cell count was analyzed in the clinical laboratory in the First Affiliated Hospital of Nanchang University.RESULTS: There were no significant differences in platelet counts (938.00 ± 270.27/L vs 962.95 ± 162.56 × 10⁹/L), red blood cell counts (8.11 ± 1.25/L vs 8.44 ± 1.48 × 10¹²/L), or hemoglobin levels (136.9 ± 8.76 g/L vs 123.21 ± 18.42 g/L) between the control and the H. pylori groups, respectively, at 18 mo. With the exception of the mean corpuscular volume (MCV), all other indicators, including white blood cell counts, hematocrit, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, red blood cell distribution width, mean platelet volume, platelet distribution width, lymphocyte count, and lymphocyte count percentage, showed no significant differences between the control and H. pylori infection groups at each time point. The MCV in the H. pylori infection group (52.32 f/L ± 2.86 f/L) was significantly lower than the control group (55.63 ± 1.89 f/L) at 18 mo (P = 0.005), though no significant differences were observed at 6 (54.40 ± 2.44 f/L vs 53.30 ± 1.86 f/L) or 12 mo (53.73 ± 2.31 f/L vs 54.80 ± 3.34 f/L).CONCLUSION: A single H. pylori infection is insufficient to cause onset of ITP or IDA and other factors may be required for disease onset.     

Long‐term infection with Helicobacter pylori in Mongolian gerbils

Objective: To investigate pathological changes occurring in the stomach of the Mongolian gerbil during long‐term Helicobacter pylori infection. Methods: Four‐week‐old male Mongolian gerbils were used, which were free from specific pathogens. Eighty Mongolian gerbils were inoculated orally with a suspension of H. pylori NCTC 11637 (0.5 mL, 2 × 10¹⁰ CFU/L) in a Brucella broth. To act as controls, a further 30 gerbils were fed with a Brucella broth only. Infected gerbils were killed 10, 25, 45, 55 and 65 weeks after infection. Control gerbils were killed at 10, 45 and 65 weeks. The stomach of each gerbil was removed and opened. Stomach samples for histological examination were fixed in neutral buffered formalin, embedded in paraffin, sectioned and stained with hematoxylin and eosin for analyzing histological changes, Giemsa stain for detecting H. pylori and Alcian blue (AB)/periodic acid?Schiff stain for examining intestinal metaplasia. Results: The Mongolian gerbil model for studying long‐term H. pylori infection was successfully established. Helicobacter pylori induced a progression from normal gastric mucosa to chronic gastritis, glandular atrophy, intestinal metaplasia and dysplasia, although no adenocarcinomas were found in the experimental animals. Conclusions: Helicobacter pylori NCTC 11637 is able to easily colonize the glandular stomach mucosa of the Mongolian gerbil. This model is stable, and the histological changes observed in the stomach are similar to those that occur in humans with H. pylori infection.     

Rebamipide prevents delay of acetic acid-induced gastric ulcer healing caused by Helicobacter pylori infection in Mongolian gerbils

In this study, we examined the effect of rebamipide, a mucoprotective drug, on gastric ulcer healing in Mongolian gerbils infected with H. pylori. Male Mongolian gerbils were inoculated with H. pylori or vehicle alone 12 hr after the production of an acetic acid-induced gastric ulcer. On day 5, the gerbils inoculated with H. pylori were divided into three groups and fed rebamipide-containing diet (0.038%, 60 mg/kg, or 0.0038%, 6 mg/kg), or standard laboratory chow. The gerbils inoculated with the vehicle were fed standard laboratory chow throughout the experiment. The gerbils were killed on day 5, 15, or 30 after ulcer production, and removed stomachs were subjected to calculation of ulcer size, culture for H. pylori, and measurement of myeloperoxidase activity, a marker for neutrophil infiltration, in ulcerated tissue. Apoptotic and proliferating cells of gastric epithelium in ulcer margins were detected by the in situ DNA nick end-labeling method and immunohistochemical staining for 5-bromo-2'-deoxyuridine (BrdU), respectively. Rebamipide did not affect colonization levels of H. pylori. Infection with H. pylori did not affect ulcer size by day 5 but significantly delayed ulcer healing by days 15 and 30, accompanied by an increase in the number of apoptotic cells, a decrease in the number of BrdU-positive cells, and an increase in myeloperoxydase activity. Rebamipide prevented delay of ulcer healing and abolished these effects of H. pylori on cell kinetics and neutrophil infiltration. In conclusion, rebamipide may prevent the delay of acetic acid-induced gastric ulcer healing caused by H. pylori through modulating cell kinetics and inhibiting neutrophil infiltration.     

Helicobacter pylori infection potentiates aspirin induced gastric mucosal injury in Mongolian gerbils

BACKGROUND: Helicobacter pylori infection and non-steroidal anti-inflammatory drugs are two major causes of gastric ulceration but interactions between H pylori and these drugs in gastric mucosal injury are unclear. AIMS: We studied the influence of experimental H pylori infection on gastric mucosal injury induced by aspirin. SUBJECTS: Male Mongolian gerbils free of specific pathogens were used. METHODS: H pylori ATCC43504 culture broth was administered by oral gavage at seven weeks of age. After three weeks, acidified aspirin (400 mg/kg) was administered orally, and three hours later the total area of gastric erosions, myeloperoxidase (MPO) activity (an index of neutrophil accumulation), thiobarbituric acid reactive substances (TBARS, an index of lipid peroxidation), and KC/GRO (a chemoattractive cytokine in rodents) were measured in gastric mucosa. To determine the role of neutrophils in these circumstances, antigerbil neutrophil rabbit serum (ANS) was administered to some animals 18 hours before aspirin. RESULTS: Aspirin caused more extensive haemorrhagic erosions (33.1 (12.3) mm2) associated with greater MPO activity (1887.7 (598.5) microU/mg protein) and TBARS (0.33 (0.14) nmol/mg protein) and KC/GRO concentrations (28.3 (9.5) pg/mg protein) in infected than in uninfected gerbils (13.7 (2.3); 204.0 (68.9); 0.12 (0.06); 3.1 (0.8), respectively) Pretreatment with ANS inhibited the increases in gastric erosions, MPO activity, and TBARS but not KC/GRO concentration. The reduction in aspirin induced mucosal injury by administration of ANS was much greater in H pylori infected animals (65%) than in uninfected animals (31%). CONCLUSIONS: H pylori infection potentiates aspirin induced gastric mucosal injury by mechanisms that include accumulation of activated neutrophils.     

Helicobacter pylori induces gastritis and intestinal metaplasia but no gastric adenocarcinoma in Mongolian gerbils

OBJECTIVE: The Mongolian gerbil is considered as the model of choice when studying adenocarcinoma related to Helicobacter pylori infection. The purpose of this study was to compare two different H. pylori strains and elucidate whether adenocarcinomas developed in gerbils. MATERIAL AND METHODS: Male gerbils were separated into three groups: one control and two groups infected with two different strains of H. pylori, TN2GF4 and SS1. At 3, 6, 12 or 18 months after inoculation 5 animals from each group were sacrificed. The stomach was used for culture, and for histology. RESULTS: Inflammation was seen after 3 months in all the infected animals. In the controls no pathology was found at any time. Intestinal metaplasia was found in both the infected groups. Glands buried in the submucusal layer, changes that might be misinterpreted as adenocarcinoma, were found in 10% of the SS1 and in 65% of the TN2GF4 animals. Adenocarcinoma was not found in any of the gerbils. CONCLUSIONS: All studies claiming to have found H. pylori-induced adenocarcinomas in gerbils describe atypical glands penetrating into the muscularis propria and interpret these as invasive growths due to cancer. An alternative interpretation is that the deranged glandular structures grow in and below the submucosa. It is suggested that atypical glands in the muscularis layer are not enough as a diagnostic criterion for gastric adenocarcinoma. It is concluded that adenocarcinoma has not yet been shown convincingly to develop in Mongolian gerbils infected with H. pylori. Nevertheless, it is a model well suited for studying gastritis, gastric ulcer and premalignant changes such as metaplasia.     

Relapsed duodenal ulcer after cure of Helicobacter pylori infection

We report a patient—a 42-year-old man—who had suffered from recurrent duodenal ulcer for about 20 years. Successful curative therapy for Helicobacter pylori infection was performed for 2 weeks with new triple omeprazole, anoxicillin, clarithromycin (OAC) treatment in October 1995, and cure of the infection was repeatedly confirmed by histology, culture, and the ¹³C urea breath test. One month after the curative therapy, recurrence of a small duodenal ulcer was observed and in February another duodenal ulcer and reflux esophagitis occurred, with severe symptoms, despite the continuous administration of ranitidine. None of the examinations to reconfirm cure of the infection revealed the presence of H. pylori. As the patient experienced continual psychological stress and smoked more frequently during the recurrent episode and had not used nonsteroidal anti-inflammatory drugs, stress and smoking appeared to play important roles in the relapse of duodenal ulcer in this patient after cure of H. pylori infection. (Received Aug. 18, 1997; accepted Jan. 23, 1998)     

Development of gastric adenocarcinoma in Mongolian gerbils after long-term infection with Helicobacter pylori

BACKGROUND AND AIM: The experimental evidence that long-term colonization of Helicobacter pylori results in the development of gastric cancer in Mongolian gerbils has been reported only by two Japanese groups to date. This study aimed to investigate the carcinogenicity of H. pylori infection in a Mongolian gerbil model. METHODS: Thirty-six Mongolian gerbils (inner Mongolian origin) were divided into two groups (male to female ratio, 1:1) and orally inoculated with a standard H. pylori strain (ATCC43504) or H. pylori161 (isolated from a Chinese patient with gastric adenocarcinoma), respectively, once a week for 5 weeks. Another 10 control gerbils were given phosphate-buffered saline. The animals were killed 8, 20, 28 and 84 weeks after inoculation for bacterial and histological examination. RESULTS: Seven inoculated gerbils died at the week 42. Overall, H. pylori colonization was detected in 24 (83%) of the 29 available inoculated gerbils. The gastric lesions were aggravated gradually over time. At week 84, moderate to severe gastritis, characterized by diffuse infiltration of mononuclear cells and formation of multiple lymphoid follicles in mucosa and submucosa, and even the lymphoepithelial lesions, were observed. Epithelial hyperplasia were dominant in almost all gerbils. Four (24%) of the 17 animals had hyperplastic polyps. Intestinal metaplasia were rarely seen (in three gerbils). Well-differentiated gastric adenocarcinomas developed in three (18%) of the 17 gerbils after 84 weeks. Of the three gerbils, one female gerbil was infected with H. pylori161 and the others (one male and one female) were infected with ATCC43504. CONCLUSIONS: The present study reconfirms that H. pylori infection alone can induce gastric adenocarcinoma in Mongolian gerbils and suggests that different species of gerbil and both standard and clinically isolated H. pylori strains can be used for investigating the carcinogenesis of H. pylori. This is the first report of the development of gastric cancer in female gerbils, which highlights the importance of using both sexes to investigate the pathogenesis of H. pylori and whether host susceptibility is influenced by sex.     

Prevalence of Helicobacter pylori infection in duodenal ulcer and gastro‐duodenal ulcer diseases in Taiwan

Background and Aim: The prevalence of Helicobacter pylori‐negative duodenal ulcer (DU) is increasing in Western countries but is rare in Japan. We aimed to examine the prevalence of H. pylori infection and the characteristics in DU and gastro‐duodenal ulcer (GDU) diseases in Taiwan. Study: All patients with an endoscopic diagnosis of DU or GDU from September 2003 to May 2004 at Taipei Veterans General Hospital were included. Rapid urease test was done for all patients, while urea breath test was carried out on those with negative rapid urease tests. A patient was considered infected if either test was positive. Results: The prevalence of H. pylori was 88.7% (555/626) in DU and 90.5% (95/105) in GDU patients. There was no difference in sex and prevalence of H. pylori between the two groups but age was higher in the GDU patients (60.1 ± 15.5 vs. 55.4 ± 15.5, P = 0.005). Of H. pylori‐negative DU patients, 28.2% (20/71) reported using non‐steroidal anti‐inflammatory drugs (NSAIDs)/aspirin, which were used by all 10 H. pylori‐negative GDU patients (100%) (P < 0.001). There was no difference in sex and age between H. pylori‐positive and negative DU patients. The prevalence rate of H. pylori in DU was not statistically different among outpatients, inpatients, and physical check‐up subjects (86.8% vs. 93.3% vs. 90.7%, P = 0.163). Conclusion: The prevalence of H. pylori infection in DU appears to be decreasing in Taiwan. Thus, eradication therapy without confirming the presence of H. pylori in DU patients cannot be recommended. NSAIDs/aspirin is the major risk factor for H. pylori‐negative DU patients, especially those with co‐morbid gastric ulcer.     

Long-term effects of Helicobacter pylori eradication in Mongolian gerbils

Background: In this study, to clarify whether Helicobacter pylori eradication alters the course of the development of gastric mucosal changes in the stomach, we examined the long-term effects of H. pylori eradication on H. pylori-inoculated gerbils. Methods: A total of 40 H. pylori-inoculated gerbils were randomized and subjected, at 22 months after inoculation, to eradication treatment with dual therapy of omeprazole plus clarithromycin, or with therapy with a novel quinolone compound, Y-34867, alone. The animals were killed at the start of administration (control group) or at 8 months after the completion of therapy (vehicle or eradication-treatment groups). Results: Severe histopathological changes in the gastric mucosa were observed in all H. pylori-inoculated gerbils at the start of administration. At 8 months after completion of therapy, the frequency of gastritis, erosion, intestinal metaplasia, and gastric carcinoid in the eradication therapy groups was markedly reduced compared with that in the control and vehicle groups. Values for anti-H. pylori IgG titer, bacterial counts, and gastrin also decreased significantly. Conclusions: These results suggest that H. pylori eradication may have had a therapeutic effect not only on gastritis, erosion, and gastric ulcer but also on glandular atrophy, intestinal metaplasia, and gastric carcinoid. Received: November 8, 2001 / Accepted: May 31, 2002 Reprint requests to: F. Hirayama     

Potential effect of chronic Helicobacter pylori infection on glucose metabolism of Mongolian gerbils

AIM: To assess the effect of Helicobacter pylori(H. pylori) infection on metabolic parameters in Mongolian gerbils.METHODS: A total of 40 male, 5- to 8-wk-old, specific-pathogen-free Mongolian gerbils(30-50 g) were randomly allocated into two groups: a control group(n = 20) and an H. pylori group(n = 20). After a two-week acclimation period, the control group was administered Brucella broth and the H. pylori group was challenged intra-gastrically five times every other day with approximately 109/CFU H. pylori ATCC43504(Cag A+, Vac A+). Each group was then divided into two subgroups, which were sacrificed at either 6 or 12 mo. The control and H. pylori subgroups each contained 10 Mongolian gerbils. Body weight, abdominal circumference, and body length were measured, and body mass index(BMI) and Lee's index were calculated. Biochemical assays were used to detect serum indexes, including glucose, glycated hemoglobin(GHb), glycated hemoglobin A1c(Hb A1c), triacylglycerol, and total cholesterol, using an automatic biochemistry analyzer. Inflammatory cytokines, including interleukin(IL)-1β, IL-2, IL-4,IL-10, IL-12, tumor necrosis factor-α(TNF-α) and interferon(IFN)-g, were assayed using ELISA. The expression of insulin and insulin-like growth factor 1(IGF-1) was detected by immunohistochemistry, and islet apoptosis was measured using the terminal deoxynucleotidyl transferase-mediated d UTP nick end labeling(TUNEL) assay.RESULTS: At each time point, body weight, abdominal circumference, BMI, and Lee's index were increased after H. pylori infection. However, these differences were not significant. H. pylori infection significantly increased the GHb(5.45 ± 0.53 vs 4.98 ± 0.22, P 0.05) and Hb A1c(4.91 ± 0.61 vs 4.61 ± 0.15, P 0.05) levels at 12 mo. We observed no significant differences in serum biochemical indexes, including fasting blood glucose, triacylglycerol and total cholesterol, at 6 or 12 mo after infection. H. pylori infection significantly increased the expression of IGF-1(P 0.05). Insulin levels from the pancreas and the apoptotic rate of islet β-cells remained unchanged. Also, we observed no significant differences among cytokines levels, including IL-1β, IL-2, IL-4, IL-10, IL-12, TNF-α and IFN-g. IL-4 was the only exception, which increased at 6(44.36 ± 25.17 vs 17.38 ± 3.47, P 0.05) and 12 mo(33.41 ± 10.00 vs 18.91 ± 5.31, P 0.05) after H. pylori infection.CONCLUSION: Long-term H. pylori infection is significantly associated with high levels of Hb A1 c in Mongolian gerbils, indicating a potential role of H. pylori infection in glucose dysregulation.     

Helicobacter pylori strain-specific modulation of gastric inflammation in Mongolian gerbils

AIM: The cag pathogenicity island (PAI) is one of potential virulence determinants of Helicobacter pylori. The Mongolian gerbil is a suitable experimental animal for the screening of virulence factors of H pylori. METHODS: Five-week-old Mongolian gerbils were inoculated with a standard H pylori strain (ATCC 43504) possessing the cag PAI or a clinical isolate lacking the genes' cluster (OHPC-0002). The animals were killed at 2, 4, 8, 24 and 48 wk after inoculation (n=5 each), and macroscopic and histopathological findings in the stomachs were compared. RESULTS: In gerbils infected with ATCC 43504, a more severe degree of infiltration of polynuclear and mononuclear cells and lymphoid follicles was observed from 4 wk after inoculation compared to gerbils infected with OHPC-0002 especially in the antrum and transitional zone from the fundic to pyloric gland area. In addition, glandular atrophy, intestinal metaplasia, gastric ulcer and hyperplastic polyps were noted in gerbils infected with ATCC 43504, whereas only mild gastric erosions occurred in those infected with OHPC-0002. CONCLUSION: Our results indicate that the cag PAI could be directly involved in gastric immune and inflammatory responses in the Mongolian gerbils, leading to a more advanced gastric disease.