Helicobacter pylori non-cytotoxic genotype enhances mucosal gastrin and mast cell tryptase

Correlation between mast cell density and histological parameters in Helicobacter pylori-associated gastritis

Background: Helicobacter pylori (H. pylori) are a major cause of chronic gastritis and peptic ulcer. This organism plays a role in gastric carcinoma and B-cell lymphoma. However, the exact pathogenesis of gastric inflammation is still unclear. Mast cells, the important inflammatory cells for allergic process, may participate in the pathogenesis of gastritis related to H. pylori infection.

Objective: Analyze the relationship between mast cell density, H. pylori intensity, histological alterations, and their severity of biopsy proven gastritis.

Methods: One hundred eleven biopsied specimens were collected from Thai patients who were diagnosed H. pylori-associated gastritis of the antrum at King Chulalongkorn Memorial Hospital between 2002 and 2005. All biopsied specimens were examined according to the Updated Sydney System. Mast cell density was evaluated by 0.1% toluidine-stained sections.

Results: The higher mast cell density was correlated with increased neutrophilic infiltration (r = 0.220, p = 0.020), chronic inflammatory cell infiltration (r = 0.381, p <0.001), and lymphoid aggregation (r = 0.271, p = 0.004). No relationship was found between mast cell density and intensity of H. pylori, glandular atrophy, or intestinal metaplasia.

Conclusion: Mast cells might take part in the pathogenesis of H. pylori gastritis.

Mast cells are critical for protection against peptic ulcers induced by the NSAID piroxicam

Many commonly used non-steroidal anti-inflammatory drugs (NSAIDs) also cause gastrointestinal toxicity, including the development of life-threatening peptic ulcers. We report that mast cell-deficient mice have an extremely high incidence of severe peptic ulceration when exposed to the NSAID piroxicam. This enhanced ulcer susceptibility can be reversed by reconstitution with mast cells. Furthermore, wild type mice treated with diphenhydramine hydrochloride, a commonly used antihistamine that blocks histamine H1 receptors, develop a similarly high incidence of peptic ulcers following piroxicam exposure. The protective effect of mast cells is independent of TNF, blockade of H2 receptors, or acid secretion. These data indicate a critical role for mast cells and the histamine that they produce in prevention and/or repair of piroxicam-induced gastric mucosal injury. Additional studies will be required to determine whether this represents a NSAID class effect that can be exploited to develop novel therapeutic strategies to limit the incidence of NSAID-induced side effects in humans.

Involvement of mast cells in gastritis caused by Helicobacter pylori: a potential role in epithelial cell apoptosis

BACKGROUND

The role(s) of mast cells (MC) in gastric mucosal inflammation caused by Helicobacterpylori is (are) still debated.

AIM

To determine whether there is an association between MC density and epithelial cell apoptosis in antral gastric mucosa infected by H pylori.

PATIENTS AND METHODS

Biopsy specimens from 122 H pylori-positive subjects with chronic active gastritis, 84 patients with non-steroidal anti-inflammatory drug-induced gastritis and 48 volunteers were included. H pylori genotypes were determined by PCR amplification of bacterial cultures. Immunohistochemical analysis was performed on tissue microarrays with anti-CD117, anti-chymase, anti-tryptase, anti-myeloperoxidase, anti-Bcl-2, anti-Bcl-x, anti-Bax and anti-caspase 3 antibodies.

RESULTS

Of the 122 patients infected with H pylori, 76 (62.3%) harboured cagA positive strains. H pylori isolates belonged to the vacAs1/m1 genotype in 82 (67%) cases, to the vacAs2/m2 genotype in 23 (18.8%) cases and to the vacAs1/m2 genotype in 17 (13.9%) cases. 61 (50%) H pylori isolates were babA2+. In patients infected with H pylori, the density of MC, and in particular the number of MC-associated epithelial cells, was correlated with a high number of apoptotic epithelial cells. Moreover, the density of MC was correlated with the number of neutrophils infiltrating the antral gastric mucosa, and was strongly increased in patients infected with cagA, vacAs1/m1 and babA2 positive strains.

CONCLUSIONS

Taken together, these data show that the density of MC can be considered as a histopathological criterion of gastritis activity in patients infected with H pylori.

Mast cell density in gastric biopsies of pediatric age group and its relation to inflammation and presence of Helicobacter pylori

Background

The aim of this study was to investigate the relationship between mast cell density, histological severity of gastritis, and presence of Helicobacter pylori (H. pylori) in the antral mucosa of pediatric patients.

Methods

The study included 352 (192 male and 160 female, < 14 years old) patients. All cases underwent endoscopy, and biopsies were obtained for histopathological examination and evaluation of Helicobacter pylori. All biopsies were evaluated according to the Sydney system and mast cell density in the antral mucosa was analyzed by Giemsa stain. Spearman's correlation test was used to determine the relationship between mast cell density and other histopathological parameters. The comparison of mast cell density between H. pylori positive and negative groups was analyzed by Mann Whitney U test.

Results

Mast cell density was 12.6 ± 0.87 in 0.25 mm² (0–81). Means of severity of gastric inflammation in H. pylori-positive and negative patients were 1.7 ± 0.6 and 0.6 ± 0.7, respectively, which was statistically significant (p = 0.0001). Mast cell density was not correlated with presence and degree of inflammation, activity, presence and score of H. pylori in the antrum (p > 0.05). There was no significant correlation between mast cell density and allergy.

Discussion

We concluded that there may be some other ways for contribution of mast cells in pathologic processes involving gastrointestinal tract in children.

Helicobacter pylori babA2, cagA, and s1 vacA genes work synergistically in causing intestinal metaplasia

AIMS

To determine any associations between the Helicobacter pylori genes babA2, oipA, cagA and the s and m alleles of vacA. In addition, to verify whether these genes work synergistically or independently in causing gastritis, peptic ulcer, and intestinal metaplasia.

METHODS

One hundred and sixty seven H pylori positive patients were studied (52 antral gastritis, 41 diffuse gastritis, 41 peptic ulcer, and 33 duodenitis). Helicobacter pylori virulence genes were amplified by means of the polymerase chain reaction.

RESULTS

Significant associations were found between babA2 and the other H pylori genes studied. When considered singly, all the genes were associated with disease diagnosis, inflammation, and intestinal metaplasia. Four H pylori groups were defined. Group A: cagA-, s2m2, babA2-; group B: cagA+, s1m1, babA2+; group C: cagA+, s1m2, babA2+; group D: cagA+, s1m2, babA2-. Group A infecting strains were associated with less severe endoscopic and inflammatory conditions, whereas group B strains were associated with the worst endoscopic and inflammatory findings. Intestinal metaplasia was a rare finding in group A infected patients (< 10%), whereas it was frequent in those infected with group B strains (48%).

CONCLUSIONS

The H pylori genes cagA, oipA "on", s1 and m1 vacA, and babA2 are associated with each other, possibly as a result of shared selective pressure. When coexpressed by the same H pylori strain, cagA, s1 and m1 vacA, and babA2 work synergistically in worsening inflammation. Infections caused by strains coexpressing cagA, s1m1 vacA, and babA2 are those at higher risk for intestinal metaplasia.

The role of mast cells in host defense and their subversion by bacterial pathogens

Mast cells (MCs) play a prominent role in the early immune response to invading pathogenic bacteria. This newly discovered role for MCs involves the release of chemoattractants that recruit neutrophils and the direct phagocytosis and killing of opsonized bacteria. Whereas these activities are clearly beneficial to the host, certain pathogens have evolved mechanisms to evoke anomalous MC responses to the detriment of the host. These include evoking phagocytosis without killing of unopsonized bacteria and the production of toxins that corrupt the release of mediators by MCs. Elucidating how pathogens subvert the activities of MCs could provide clues to limiting the pathological activities of these cells during infectious diseases.

Antigastric autoantibodies in Helicobacter pylori infection: role in gastric mucosal inflammation

The aim of the study was to ascertain whether there is an association between the presence of serum parietal cell autoantibodies (PCA) and: (1) Helicobacter pylori infection; (2) the presence and degree of gastritis and intestinal metaplasia; and (3) the H. pylori infecting strain. Gastric mucosal biopsies were obtained from 49 consecutive patients in order to assess and grade gastritis, make a histological diagnosis, and culture and genotype H. pylori. H. pylori infection was present in 26 patients (group 1), had been present in 17 patients (group 2), and the remaining 6 (group 3) had never had the infection. The infecting strain was cagA positive in 21 of 26 group 1 patients. Positive PCA results were found in 84%, 76%, and 14% of patients in groups 1, 2, and 3, respectively. PCA results were correlated with anti-H. pylori antibody titers (P<0.05). In group 2 patients, PCA were associated with the degree of antral gastritis (Fisher's exact test P<0.05). cagA status was not associated with the presence of PCA (chi2=0.68, NS). The frequency of positive findings for PCA in group 2 was higher in patients with (90%) than in those without (50%) intestinal metaplasia.

IN CONCLUSION

(1) H. pylori infection is associated with the production of PCA, which, after eradication of the infection, persist and might contribute to the persistent antral chronic gastritis and intestinal metaplasia; (2) the gastric lesions associated with infections sustained by the more-virulent H. pylori strains do not appear to be due to the induction of antigastric autoantibodies.