Association between Helicobacter felis-induced gastritis and elevated glycated hemoglobin levels in a mouse model of type 1 diabetes

Helicobacter pylori infection has been described in association with increases in glycated hemoglobin (HbA(1c)) levels in patients with type 1 diabetes. The purpose of the present study was to use an animal model of Helicobacter infection to test, under controlled conditions, the hypothesis that infection is associated with high HbA(1c) levels. Diabetes was induced in C57BL/6 mice by administration of streptozotocin, and the mice were orally inoculated with H. felis. Six weeks after inoculation, infected mice (n=10) showed gastritis scores significantly greater (P=.01) than those of uninfected mice (n=10). HbA(1c) levels were significantly higher in infected mice with gastritis (11.6%; n=6) than in infected mice without gastritis (8.4%; n=4) or uninfected mice (7.6%; n=10). It was concluded that gastritis induced by H. felis is associated with increased HbA(1c) levels in the mouse model of streptozotocin-induced diabetes.

Helicobacter hepaticus-induced colitis in interleukin-10-deficient mice: cytokine requirements for the induction and maintenance of intestinal inflammation

We have previously shown that specific-pathogen-free interleukin-10 (IL-10)-deficient (IL-10 KO) mice reconstituted with Helicobacter hepaticus develop severe colitis associated with a Th1-type cytokine response. In the present study, we formally demonstrate that IL-12 is crucial for disease induction, because mice deficient for both IL-10 and IL-12 p40 show no intestinal pathology following H. hepaticus infection. By using monoclonal antibodies (MAbs) to IL-12, gamma interferon (IFN-gamma), and tumor necrosis factor alpha (TNF-alpha), we have further analyzed the role of these cytokines in the maintenance of the Th1 response and inflammation in IL-10 KO mice with established H. hepaticus-induced colitis. Treatment of infected colitic IL-10 KO mice with anti-IL-12 p40 resulted in markedly reduced intestinal inflammation, colonic IFN-gamma, TNF-alpha, and inducible nitric oxide synthase (iNOS) mRNA levels, and H. hepaticus-specific IFN-gamma secretion by mesenteric lymph node (MLN) cells compared to the findings in control MAb-treated mice. Moreover, the diminished pathology was associated with decreased numbers of colonic CD3(+) T cells and significantly reduced frequencies of Helicobacter-reactive CD4(+) Th1 cells in MLN. In contrast, anti-IFN-gamma and/or anti-TNF-alpha had no effect on intestinal inflammation in IL-10 KO mice with established colitis. Using IL-10/IFN-gamma double-deficient mice, we further show that IFN-gamma is not required for the development of colitis following H. hepaticus infection. MLN cells from infected IL-10/IFN-gamma KO animals secreted elevated amounts of IL-12 and TNF-alpha following bacterial antigen stimulation, indicating alternative pathways of disease induction. Taken together, our results demonstrate a crucial role for IL-12 in both inducing and sustaining intestinal inflammation through recruitment and maintenance of a pool of pathogenic Th1 cells.

Gastritis and intestinal metaplasia in Syrian hamsters infected with Helicobacter aurati and two other microaerobes

Chronic gastritis and intestinal metaplasia associated with naturally occurring colonization by Helicobacter aurati and two other microaerobic species were observed in Syrian hamsters. Thirty-five hamsters, between 7 and 12 months of age, were evaluated from two research and three commercial facilities. Microaerobic bacteria were cultured from the hamster stomachs. These bacteria included H. aurati, a fusiform, urease-positive species; a second novel helical, urease-negative Helicobacter sp.; as well as a smaller, urease-negative Campylobacter sp. Southern blot analysis detected Helicobacter spp. DNA in the gastric tissues of all 35 hamsters; 15 hamsters also had Campylobacter sp. DNA in their gastric tissues. When examined by light microscopy, argyrophilic bacteria consistent with H. aurati or the second Helicobacter sp. were present in antral sections of 12 out of the 15 hamsters where bacteria were seen, while 9 out of the 15 hamsters had bacteria resembling the Campylobacter sp. The presence of Helicobacter spp. but not the presence of Campylobacter sp. was significantly correlated to gastritis severity (P < 0.0001 for Helicobacter spp., P = 0.6025 for Campylobacter sp.) and intestinal metaplasia, as measured by numbers of goblet cells (P = 0.0239 for Helicobacter spp., P = 0.5525 for Campylobacter sp.). Severely affected hamsters also had Giardia sp. within their metaplastic gastric pits. Hamsters with naturally occurring helicobacter-associated gastritis provide a model for studying the development of intestinal metaplasia and gastric giardiasis in H. pylori-infected humans.

Age-related alterations in 32P-postlabeled DNA adducts in livers of mice infected with the tumorigenic bacterial pathogen, Helicobacter hepaticus

Helicobacter hepaticus causes chronic active hepatitis and liver tumors in mice, with associated increase in reactive oxygen species. Indigenous (I)-compounds are bulky DNA adducts present at low levels and detected by 32P-post-labeling. Some may be caused by reactive oxygen species; others occur normally and decrease during liver tumorigenesis. The identity of most is unknown. We investigated whether mouse liver infection by H. hepaticus and resulting progression of hepatic lesions would be associated with qualitative or quantitative changes in I-compounds. Mice were 3, 6, 9, and 12 months of age; liver disease ranged from minimal through marked. In control A/J mice, up to 20 I-compounds were detected, and the total level of these did not change with age, whereas 11 individual I-compounds showed marked age-related differences. These appeared to be coordinately regulated, as the total of these 11 adducts was constant at 6-12 months. In A/JNCr mice naturally infected with H. hepaticus, up to 12 hepatic I-compounds were found. Total levels varied markedly with age and were high at 6 and 12 months. Neither total adduct levels, nor the amount of any individual adduct, correlated positively with severity of hepatic lesions; in some cases, highest levels were found in livers with least disease. Thus, liver infection and tumorigenesis by H. hepaticus was not associated with an increase in any 32P-postlabeled DNA adduct. Marked, and distinct, age-related changes in total or individual adducts in control and infected mice suggest a role in the physiological alterations of aging and in host response to infection.

Positive effect of rebamipide on gastric permeability in mice after eradication of Helicobacter felis

BACKGROUND

Despite Helicobacter pylori eradication, gastric inflammation persists for months or years. Preliminary results have indicated that an increase in gastric permeability could be one reason. Our aim was to evaluate the effect of a mucosal protective drug, rebamipide, on gastric permeability in a model of H. felis-infected mice.

METHODS

Thirty-three C57/BL6 mice were inoculated with H. felis, and seven controls were kept non-inoculated. After 2 months 20 infected mice were treated with omeprazole, amoxicillin, and clarithromycin for 1 week and then for 4 weeks with either rebamipide (n = 9) or placebo (n = 11). The 13 remaining mice were kept untreated. After cessation of treatment, a fragment of antrum obtained from each mouse was mounted in a small Ussing chamber to study the electric resistance of the tissue (R) and antral permeability.

RESULTS

No modification of the paracellular permeability (R, JNa, JMan) was observed in either group. However, the transcellular permeability to horseradish peroxidase (HRP) was significantly increased in H. felis-infected non-treated mice (1131 +/- 463, 948 +/- 339, and 182 +/- 312 ng/h x cm2) as compared with non-infected controls (469 +/- 262, 458 +/- 261, and 10 +/- 6 ng/ h x cm2, for J3H-HRP, JD, and JHRPi, respectively) (P < 0.003). Eradication of the bacteria by antibiotics without subsequent treatment with rebamipide led to a non-significant decrease in the HRP fluxes. However, when rebamipide was used after the antibiotic treatment, a significant (P < 0.01) decrease in HRP fluxes as compared with non-treated mice was observed.

CONCLUSIONS

These results confirm that gastric permeability to macromolecules remains increased despite H. felis eradication and show that rebamipide can facilitate the normalization of gastric permeability to macromolecules after bacterial eradication.

Development of a combined PCR-culture technique for the rapid detection of Arcobacter spp. in chicken meat

A combined PCR-culture technique was developed to detect Arcobacter spp. in fresh chicken meat. Following a short selective enrichment of chicken samples, bacterial DNA was extracted and amplified using primers targeted at the genes encoding 16S rRNA of Arcobacter spp. The selected primers amplify a 181-bp fragment from all Arcobacter spp., whereas no PCR product is generated for other bacteria, including the closely related Campylobacter and Helicobacter species. The assay was used to screen 96 retail-purchased chicken samples for the presence of Arcobacter spp. Fifty-three percent of the samples analysed were positive for this micro-organism. The assay is simple and sensitive and reduces the amount of time required to positively detect Arcobacter spp. in poultry meat.

Impact of Helicobacter hepaticus infection in B6C3F1 mice from twelve National Toxicology Program two-year carcinogenesis studies

Male and female B6C3F1 mice from 12 National Toxicology Program (NTP) 2-yr carcinogenesis studies were found to be infected with Helicobacter hepaticus. Many of the male mice from 9 of these studies had an associated hepatitis (affected studies). Helicobacter hepaticus has been reported to be associated with an increased incidence of hepatitis and hepatocellular neoplasms in the A/JCr male mouse. We attempted to determine if the data from the Helicobacter-affected NTP B6C3F1 mouse studies were compromised and unsuitable for cancer hazard identification. The incidences of neoplasms of the liver (both hepatocellular and hemangiosarcoma) but not of other organs in control male B6C3F1 mice were increased in affected studies as compared with control males from unaffected studies. The increased incidence of hepatocellular neoplasms was observed in those males exhibiting H. hepaticus-associated hepatitis. Other observations further differentiated control male mice from affected and unaffected studies. H-ras codon 61 CAA to AAA mutations were less common in liver neoplasms from males from affected studies as compared with historical and study controls. In addition, increases in cell proliferation rates and apoptosis were observed in the livers of male mice with H. hepaticus-associated hepatitis. These data support the hypothesis that the increased incidence of liver neoplasms is associated with H. hepaticus and that hepatitis may be important in the pathogenesis. Therefore, interpretation of carcinogenic effects in the liver of B6C3F1 mice may be confounded if there is H. hepaticus-associated hepatitis.

[Biological diagnostic and therapeutic study on the infection of Helicobacter heilmannii]

OBJECTIVE

To study the epidemiology, microbiology, pathogenicity, diagnosis and therapy of Helicobacter heilmannii (Hh) infection.

METHODS

Morphological methods, such as Gram staining of gastroscopic biopsy smears, Giemsa staining of histological slides and scanning electromicroscopy(SEM), and biochemistry techniques such as urease test(CLO), 14C urea breath test(UBT) were used to identify Hh infection in natural populations. The 16S rRNA gene of 4 strains of Hh were amplified, sequenced and analysed, using bacterial universal and Helicobacter genus-specific primers.

RESULTS

Twenty cases of Hh infection were found in 992 peoples with the positive rate of 2.0%. There existed the phenomena of intrafamily cluster of Hh infection. 14 case of the gastic tissues were CLO positive and 3 cases of these patients were UBT positive, the bacterium cannot be isolated in vitro. Sporadic invasion of lymphocyte/plasmic cell were found in gastric mucosa with Hh infection. Formation of lymph follicles and invasion of neutrophlic cell could be found too. The "old triple therapy" regimen could eradicate Hh easily. The homology of 16S rRNA gene among 4 strains was between 98.7%-99.7%, and can not be devided into two subtypes. The homology between Hh and H. felis or Hp were 95.6%-96.5% and 96.4%-97.1%, respectively.

CONCLUSION

The prevalence of Hh in southern China is higher than that reported abroad. There may exist animal to person and person to person transmission mechanisms. Hh should be a new Helicobacter with lower activity of urease and weaker pathogenicity when compared with H. pylori. The infection of Hh is easy to eradicate through drug therapy.

Evaluation of experimental therapeutics in a new mouse model of Helicobacter felis utilizing 16S rRNA polymerase chain reaction for detection

BACKGROUND

A new mouse model of Helicobacter felis infection, which mimics the human infection observed with H. pylori, has recently been developed utilizing polymerase chain reaction (PCR) based on the 16S rRNA gene sequence for detection of infection.

METHODS

We tested several therapeutic regimens in this model, including some currently utilized in the clinic and some shown ineffective in the clinic.

RESULTS

The therapeutic results obtained by PCR with this model are consistent with results observed in the published human H. pylori clinical trials and also with results obtained in another H. felis mouse model utilizing culture and histology.

CONCLUSIONS

These results support further use of this new model in screening for new therapeutic regimens for the management of Helicobacter disease.

The stability of amoxycillin, clarithromycin and metronidazole in gastric juice: relevance to the treatment of Helicobacter pylori infection

Although omeprazole is an important component in anti-Helicobacter pylori therapeutic regimes using clarithromycin, amoxycillin and metronidazole, the mechanism by which it enhances antimicrobial action is unknown. One potential explanation for this effect is increased antibiotic chemical stability resulting from gastric pH changes induced by co-administration of omeprazole. The chemical stability of clarithromycin, amoxycillin and metronidazole was investigated in aqueous solutions and in human gastric juice collected before and after a 7-day course of omeprazole. Amoxycillin, clarithromycin and metronidazole were prepared in buffered aqueous solutions of pH 1.0 to 8.0 and in gastric juice of pH 2.0 and 7.0. The gastric juice samples were obtained from fasted H. pylori-negative volunteers before and after they had received a 7-day course of omeprazole. All the samples were incubated at 37 degrees C and analysed at intervals by HPLC. Amoxycillin, clarithromycin and metronidazole were stable in aqueous solutions of pH 4.0-7.0, pH 5.0-8.0 and pH 2.0-7.0, respectively. At pH 2.0, the degradation half-lives were 19.0 +/- 0.2 h, 1.3 +/- 0.05 h and 2200 +/- 1100 h, respectively. In gastric juice samples of pH 2.0, the degradation half-lives were 15.2 +/- 0.3 h, 1.0 +/- 0.04 h and > or = 800 h, respectively. The half-lives of the drugs in the gastric juice samples of pH 7.0 were all > 68 h. The co-administration of omeprazole with amoxycillin or clarithromycin is likely to increase the chemical stability of amoxycillin and clarithromycin in gastric juice. Clarithromycin degrades rapidly at normal gastric pH (1.0-2.0) but amoxycillin and metronidazole are sufficiently stable at this pH to maintain an antibacterial concentration in the stomach.

Parietal cell hyperactivity is not due to Helicobacter pylori infection in patients with duodenal ulcer

OBJECTIVE

To determine the relationship between Helicobacter pylori infection and parietal cell mass and functional status in 10 patients with duodenal ulcer and 22 patients with functional dyspepsia.

METHODS

We measured pentagastrin-stimulated acid secretion, determined the activity status of parietal cells on the basis of ultrastructural morphological features, and measured parietal cell mass and canalicular area with computerized densitometric morphometry. The number of antral G cells per square millimeter of mucosa was estimated inmunohistochemically, and basal serum gastrinemia was determined.

RESULTS

In patients with duodenal ulcer, acid secretion, the percentage of activated parietal cells, and canalicular area were increased, but there was no difference between patients and dyspeptic controls in parietal cell mass. Helicobacter pylori infection did not modify these parameters, although it was associated with basal hypergastrinemia.

CONCLUSION

In patients with duodenal ulcer, parietal cells display functional hyperactivity, which causes hypersecretion of acid; this effect is apparently unrelated to Helicobacter pylori infection.

Evaluation of gastric ulcer healing with mucosal microvascular architecture

BACKGROUND/AIMS

There is presently no consensus on how long treatment of gastric ulcers should be continued to prevent ulcer recurrence. Therefore, we investigated the histologic state of healing, and the recurrence of gastric ulcers with Helicobacter pylori infection classified by gastric mucosal microvascular architecture as completely and incompletely healed.

MATERIAL AND METHODS

We obtained biopsy specimens from healed gastric ulcers in 71 patients who had been treated for eight weeks with omeprazole. The gastric mucosal microvascular architecture of the biopsy specimens was observed by the alkaline phosphatase staining method.

RESULTS

We found a significant correlation between the mucosal microvascular architecture in the biopsy specimens and the histologic state of ulcer healing Recurrences were significantly more frequent in ulcers classified by microvascular architecture as incompletely healed than in completely healed ulcers.

CONCLUSION

Observing the microvascular architecture of healed gastric ulcers is very useful for judging the state of healing, and therapy should be continued until ulcers are classified by this method as completely healed.

Therapeutic immunization against Helicobacter mustelae in naturally infected ferrets

BACKGROUND & AIMS

Helicobacter infection of the gastric antrum is responsible for a number of gastric disorders. Antibiotic therapy is lengthy and is not always effective. It has been shown previously that oral immunization against Helicobacter felis in mice can prevent colonization after challenge. The aim of this study was to investigate the efficacy of therapeutic immunization in eradicating an established Helicobacter infection and in reducing gastritis.

METHODS

Domestic ferrets, confirmed to be infected with Helicobacter mustelae by gastric endoscopy, were orally immunized with varying doses of purified Helicobacter pylori urease in combination with the mucosal adjuvant cholera toxin. Ferrets were assessed 1 week and 6 weeks after treatment for infection and pathology.

RESULTS

Therapeutic immunization eradicated Helicobacter colonization in 30% of all immunized ferrets, although there was no difference in efficacy between the varying doses of antigen tested. The difference was statistically significant when compared with animals administered cholera toxin alone or buffer (P = 0.04). The intensity of inflammation was also significantly reduced in immunized animals (P = 0.0003).

CONCLUSIONS

Oral immunization with purified H. pylori urease and cholera toxin can eradicate H. mustelae in a natural host pathogen model. Oral immunization of chronically infected animals markedly reduced gastric inflammation.

Prevalence of Helicobacter-like organisms in porcine gastric mucosa: a study of swine slaughtered in Italy

Recent reports described some cases of gastritis in man caused by an uncultured gram-negative spiral bacterium morphologically identical to organisms observed in the stomachs of mammalians (e.g. cats, dogs, pigs). The aim of the present study is to confirm the presence of these bacteria in Italian swine. Tightly spiralled organisms (Gastrospirillum suis) were found in the stomach of eight (9.4%) out of 85 pigs examined. The bacteria were always associated with macroscopic lesions indicative of gastritis. Attempts to culture H. pylori or Helicobacter-like organisms were unsuccessful. The possibility that Gastrospirillum may be a zoonotic pathogen, with transmission occurring from pigs to humans, is discussed.