Five month persistence of Helicobacter pylori infection in guinea pigs

Diminishing of Helicobacter pylori adhesion to Cavia porcellus gastric epithelial cells by BCG vaccine mycobacteria

Mycobacterium bovis onco-BCG bacilli used in immunotherapy of bladder cancer are candidates for training of immune cells towards microbial pathogens. Increasing antibiotic resistance of gastric pathogen Helicobacter pylori (Hp) prompts the search for new anti-Hp and immunomodulatory formulations. Colonization of gastric mucosa by Hp through mucin 5 AC (MUC5AC) ligands could potentially be a therapeutic target. The aim of this study was to examine the ability of onco-BCG mycobacteria to reduce Hp adhesion to gastric epithelial cells using Cavia porcellus model. Animals were inoculated per os with 0.85% NaCl, Hp alone, onco-BCG alone or with onco-BCG and Hp. After 7/28 days Mucin5AC and Hp binding to gastric epithelium were assessed in gastric tissue specimens by staining with anti-Mucin5AC and anti-Hp antibodies, respectively, both fluorescently labeled. Primary gastric epithelial cells were treated ex vivo with live Hp or Hp surface antigens (glycine extract or lipopolysaccharide) alone or with onco-BCG. In such cells MUC5AC and Hp binding were determined as above. Mycobacteria reduced the amount of MUC5AC animals infected with Hp and in gastric epithelial cells pulsed in vitro with Hp components. Decrease of MUC5AC driven in cell cultures in vitro and in gastric tissue exposed ex vivo to mycobacteria was related to diminished adhesion of H. pylori bacilli. Vaccine mycobacteria by diminishing the amount of MUC5AC in gastric epithelial cells may reduce Hp adhesion.

Animal Models and Helicobacter pylori Infection

Helicobacter pylori colonize the gastric mucosa of at least half of the world’s population. Persistent infection is associated with the development of gastritis, peptic ulcer disease, and an increased risk of gastric cancer and gastric-mucosa-associated lymphoid tissue (MALT) lymphoma. In vivo studies using several animal models have provided crucial evidence for understanding the pathophysiology of H. pylori-associated complications. Numerous animal models, such as Mongolian gerbils, transgenic mouse models, guinea pigs, and other animals, including non-human primates, are being widely used due to their persistent association in causing gastric complications. However, finding suitable animal models for in vivo experimentation to understand the pathophysiology of gastric cancer and MALT lymphoma is a complicated task. In this review, we summarized the most appropriate and latest information in the scientific literature to understand the role and importance of H. pylori infection animal models.

Helicobacter pylori Infection Acts Synergistically with a High-Fat Diet in the Development of a Proinflammatory and Potentially Proatherogenic Endothelial Cell Environment in an Experimental Model

Classic atherosclerosis risk factors do not explain all cases of chronic heart disease. There is significant evidence that gut microbiota may influence the development of atherosclerosis. The widespread prevalence of chronic Helicobacter pylori (H. pylori, HP) infections suggests that HP can be the source of components that stimulate local and systemic inflammatory responses. Elevated production of reactive oxygen species during HP infection leads to cholesterol oxidation, which drives atherogenesis. The aim of this study is to explore the link between persistent HP infection and a high-fat diet in the development of proinflammatory conditions that are potentially proatherogenic. An in vivo model of Caviae porcellus infected with HP and exposed to an experimental diet was investigated for the occurrence of a proinflammatory and proatherogenic endothelial environment. Vascular endothelial primary cells exposed to HP components were tested in vitro for oxidative stress, cell activation and apoptosis. The infiltration of inflammatory cells into the vascular endothelium of animals infected with HP and exposed to a high-fat diet was observed in conjunction with an increased level of inflammatory markers systemically. The arteries of such animals were the least elastic, suggesting the role of HP in arterial stiffness. Soluble HP components induced transformation of macrophages to foam cells in vitro and influenced the endothelial life span, which was correlated with Collagen I upregulation. These preliminary results support the hypothesis that HP antigens act synergistically with a high-fat diet in the development of proatherogenic conditions.

The effect of Helicobacter pylori infection and different H. pylori components on the proliferation and apoptosis of gastric epithelial cells and fibroblasts

Background

Helicobacter pylori colonizes the human gastric mucosa, causing chronic inflammation, peptic ulcers and gastric cancer. A cascade of harmful processes results from the interaction of these bacteria with the gastric epithelium.

Aim

To investigate these processes in terms of upregulation of oxidative stress and cell apoptosis and downregulation of the pro-regenerative activity of cells.

Methods

We employed an in vivo guinea pig model at 7 or 28 days postinoculation with H. pylori, corresponding to an acute or chronic stage of infection, respectively, and an in vitro model of guinea pig primary gastric epithelial cells and fibroblasts treated with bacterial components: glycine acid extract (GE), urease subunit A (UreA), cytotoxin-associated gene A protein (CagA) and lipopolysaccharide (LPS). Cells were evaluated for metabolic activity (MTT reduction), myeloperoxidase (MPO) and metalloproteinase (MMP-9) secretion, lipid peroxidation (4-hydroxynonenal (4HNE)), migration (wound healing), proliferation (Ki-67 antigen) and cell apoptosis (TUNEL assay; Bcl-xL, Bax, Bcl-2 expression; caspase 3 cleavage).

Results

Significant infiltration of the gastric mucosa by inflammatory cells in vivo in response to H. pylori was accompanied by oxidative stress and cell apoptosis, which were more intense 7 than 28 days after inoculation. The increase in cell proliferation was more intense in chronic than acute infection. H. pylori components GE, CagA, UreA, and LPS upregulated oxidative stress and apoptosis. Only H. pylori LPS inhibited cell migration and proliferation, which was accompanied by the upregulation of MMP-9.

Conclusions

H. pylori infection induces cell apoptosis in conjunction with increased oxidative stress. Elevated apoptosis protects against deleterious inflammation and neoplasia; however, it reduces cell integrity. Upregulation of cell migration and proliferation in response to injury in the milieu of GE, CagA or UreA facilitates tissue regeneration but increases the risk of neoplasia. By comparison, downregulation of cell regeneration by H. pylori LPS may promote chronic inflammation.

Upregulation of MUC5AC production and deposition of LEWIS determinants by HELICOBACTER PYLORI facilitate gastric tissue colonization and the maintenance of infection

Background

Helicobacter pylori bacteria colonize human gastric mucosa, cause chronic inflammation, peptic ulcers and gastric cancer. Colonization is mediated by H. pylori adhesins, which preferentially bind mucin 5 (MUC5AC) and Lewis (Le) determinants. The aim of this study was to evaluate the influence of H. pylori and their components on MUC5AC production and deposition of LeX/LeY in gastric epithelial cells in relation to bacterial adhesion using Caviae porcellus primary gastric epithelial cells and an in vivo model of experimental H. pylori infection in these animals.

Methods

MUCA5C and LeX/LeY were induced in vitro by live H. pylori reference strain CCUG 17874 (2 × 10⁷ CFU/ml), H. pylori glycine acid extract (GE), 10 μg/ml; cytotoxin associated gene A (CagA) protein, 1 μl/ml; UreA urease subunit, 5 μg/ml; lipopolysaccharide (LPS) 25 ng/ml and imaged by fluorescence microscopy after anti-MUC5AC or anti-LeX/LeY FITC antibody staining. Bacterial adhesion was imaged by using anti-H. pylori FITC antibodies. The animals were inoculated per os with H. pylori (3 times in 2 days intervals, 1 × 10¹⁰ CFU/ml). After 7 or 28 days an infection and inflammation were assessed by histological, serological and molecular methods. Gastric tissue sections of infected and control animals were screend for MUCA5C and LeX, and H. pylori adhesion as above.

Results

MUC5AC production and deposition of Lewis determinants, especially LeX were upregulated in the milieu of live H. pylori as well as GE, CagA, UreA or LPS in vitro and in vivo during infection, more effectively in the acute (7 days) than in the chronic (28 days) phase of infection. This was related to enhanced adhesion of H. pylori, which was abrogated by anti-MUC5AC and anti-LeX or anti-LeY antibody treatment.

Conclusions

Modulation of MUCA5C production and LeX/LeY deposition in the gastric mucosa by H. pylori can significantly increase gastric tissue colonization during H. pylori infection.

Detection of Helicobacter species in liver and stomach tissues of patients with chronic liver diseases using polymerase chain reaction-denaturing gradient gel electrophoresis and immunohistochemistry

OBJECTIVE

Helicobacter DNA has been detected in the hepatobiliary tree of patients with chronic liver diseases (CLD). The presence of H. pylori in the stomach compared with in the liver of the same patients with CLD has not been studied, therefore to the aim of this study was to investigate the presence of Helicobacter DNA and antigens in the liver and stomach of Polish patients with chronic liver diseases using molecular and immunological methods.

MATERIAL AND METHODS

Gastric mucosa and liver tissue samples and sera were collected from 97 Polish patients with CLD. Anti-H. pylori antibodies were detected by enzyme immunoassay (EIA), and H. pylori-like antigens detected by immunohistochemistry. Helicobacter DNA was detected in stomach and liver samples using a semi-nested Helicobacter genus-specific polymerase chain reaction (PCR) assay, and Helicobacter species identified by denaturing gradient gel electrophoresis (DGGE) and sequencing analysis of amplified PCR products.

RESULTS

H. pylori was identified by DGGE and sequence analysis in 60/62 (97%) and 25/25 (100%) of the gastric and liver Helicobacter genus-positive samples, respectively, whereas DNA of H. heilmannii was detected in 2/62 (3%) of the Helicobacter genus-positive gastric samples. H. pylori cagA gene was detected in 23/62 (36%) and 3/25 (12%) gastric and liver tissue samples, respectively. H. pylori-like antigens were detected in 61/97 (63%) gastric mucosa and in 40/97 (41%) liver tissue samples.

CONCLUSIONS

H. pylori-like organisms appeared to dominate the gastric mucosa and liver tissue of Polish patients with CLD. The prevalence of the cagA gene was higher in stomach compared with liver samples, which suggests a possible role of cagA negative H. pylori-like organisms in CLD. On the other hand, no significant correlation was found between the presence of H. pylori-like DNA and antigens in the liver and liver function tests.

Establishment of mouse models with long-term infection of H. pylori

AIM: To develop a mouse model with long-term infection of H. pylori.

METHODS: Each mouse was inoculated with H. pylori Sydney strain 1 (SS1). Noninfected control mice and infected mice were killed at 4, 12 and 24 wk after H. pylori infection. A piece of gastric mucosa obtained from the posterior wall of the antrum of each mouse was used for culture of H. pylori, rapid urease testing and histopathological detection. Serum was obtained to measure the IgG antibody level to H. pylori.

RESULTS: After 4 wk of infection, the H. pylori was cultured from 6 of 7 infected Babl/c mice and 5 of 7 the H. pylori-infected C57BL/6 mice. After 12 and 24 wk of infection, all of 7 infected Babl/c and 6 of 7 the H. pylori-infected C57BL/6 mice showed the positive results. At the different wk, the rapid urease test results were consistent with the H. pylori culture test. At 12 wk after inoculation, chronic inflammation was observed in the pyloric mucosa by histopathological examination. At 24 wk after inoculation, lymphoid follicles were especially conspicuous in the submucosa, and they were also found in the deep portion of the mucosa.

CONCLUSION: H. pylori SS1 can colonize easily in the glandular stomach mucosa of mouse, and the histopathological changes are similar to those of humans with H. pylori infection.