Does the stomach adapt to Helicobacter pylori?

Prevalence of Helicobacter pylori infection in two Spanish regions with different incidence of gastric cancer

It is a cross-sectional study, comparing the prevalence of Helicobacter pylori infection (prevalence of IgG antibodies to H. pylori) in the healthy population of Ubrique and Grazalema (mountain location, mortality from stomach cancer 20/100,000) and in Barbate, (coastal location, mortality from stomach cancer 10/100,000) in the province of Cadiz, southern Spain. The subjects were randomly selected, 163 men and 169 women, 18 years or older; 179 persons were studied in the inland, and 154 in the littoral in January 1997. Of the 332 subjects investigated, 43% were positive, a mean antibody titer of 337 IU/1 (95 % CI: 254-420), and 56% were negative, with a mean titer of 18 IU/1 (95% CI: 15-19). In the coastal population, 30% has positive titers and 54% in the mountain location. By age: 18-40 years, 30% of littoral and 41% of inland population had positive titers; 41-60 years, 35% of those living in the littoral and 58% of inland population had positive titers; > 60 years, 24% of coastal inhabitants and 62% of those living in the inland had positive titers. Living in mountain locations in the province of Cadiz involves a greater ecological risk for H. pylori infection (p < 0.05).

Association of Helicobacter pylori infection with gastric adenocarcinoma

Gastric adenocarcinoma is the most prevalent cancer in South Korea, and Helicobacter pylori (H. pylori) infection is also common. This study was performed to examine the association between H. pylori infection and gastric cancer, taking into account various other factors. To investigate the association between gastric adenocarcinoma and H. pylori infection, determined by urease-positive reaction in the CLO test, a total of 175 paired specimens (175 tumor and 175 tissues adjacent to tumor) of stomach cancer patients and a total of 113 control specimens were obtained. The positive H. pylori infection rates were 78.9% (138/175) among the patients in specimens of tumor or tissues adjacent to the tumor and 41.6% (47/113) among controls in the CLO test. A positive correlation between H. pylori infection and gastric cancer was observed (age-adjusted odds ratio, 7.0; MH chi2=34.5 with P<0.0005). These data suggest that stomach cancer patients in Korea have high infection rates of H. pylori regardless of site specificity, and this infection might be causally associated with stomach cancer.

Non-random loss of chromosome 3 during transition of Helicobacter pylori-associated gastric MALT to B-cell MALT lymphoma revealed by fluorescence in situ hybridization

Acquired gastric mucosa-associated lymphoid tissue (MALT) accumulates as a result of long-standing Helicobacter pylori (H. pylori) infection and from this acquired MALT, low-grade B-cell MALT lymphoma may develop. Carcinogenesis is a multistep, multifactorial process involving the progressive accumulation of genetic changes. To determine whether numerical chromosomal alterations are involved in the transition of H. pylori-associated human gastric MALT to low-grade B-cell MALT lymphoma, frozen biopsy specimens prospectively obtained from H. pylori positive gastric MALT and gastric MALT lymphoma patients, as well as normal control patients (normal gastroscopy/gastric mucosal histology/H. pylori negative), were analyzed by fluorescence in situ hybridization (FISH). Fluorescent, directly labeled alpha-satellite DNA probes, specific for the centromeres of chromosomes 1, 3, 4, 11, 17 and Y were used in this study. The non-random loss of chromosome 3 was detected in two MALT patients and in all five MALT lymphoma patients. Trisomy 17 was detected in one MALT patient and one MALT lymphoma patient. Trisomy 1 was detected in a single MALT lymphoma patient as was trisomy 3. None of the MALT patients had trisomy 3 or trisomy 1. Monosomy 17 was noted in one MALT lymphoma patient. Clonal aneusomy was not observed in any patient for chromosomes Y, 4 or 11. These results suggest that the consistent loss of chromosome 3 may be an important genetic alteration in the transformation of H. pylori-associated gastric MALT into low-grade B-cell gastric MALT lymphoma.

Normal gastric histology in Helicobacter pylori-infected children

BACKGROUND

In adults, Helicobacter pylori infection is always associated with gastritis or ulcer. However, very active gastritis and ulcers are rarely seen in children. The aim of the present work was to study the relationships between H. pylori and gastric mucosa in children.

METHODS

Eighty infected children and adolescents including 48 (60%) neurologically impaired institutionalized patients, aged 2 months-22 years (mean 11.7 +/- 5.2 years) were studied retrospectively. All the patients underwent gastroscopy, and three antral and two fundic biopsy specimens were taken for histology and bacteriology.

RESULTS

A normal gastric mucosa was found in 22 of 80 patients (27.5%), whereas the others had gastritis (n = 58, 72.5%). There were no statistical differences between patients with normal histology and those presenting with gastritis for age, sex, ethnic background, symptoms, and the degree of bacterial colonization. The macroscopic aspect of gastritis was less frequently found in children with a normal histology compared with those with histological gastritis (p < 0.001).

CONCLUSIONS

These data show that H. pylori infection can be associated with a normal gastric histology in children.

Up-regulation of CD44 and ICAM-1 expression on gastric epithelial cells by H. pylori

Interaction between lymphocytes and epithelial cells may play a key role in Helicobacter pylori (H. pylori)-associated gastric mucosal inflammation. This interaction process is at least partially mediated by various cell adhesion molecules. The aims of the present study were to assess using flow cytometric analysis whether H. pylori directly or supernatants from H. pylori-activated peripheral blood mononuclear cells (PBMC) can affect the expression of adhesion molecules on the gastric epithelial cell line AGS in vitro. The results showed that resting AGS cells expressed CD44 and ICAM-1. Co-culture of AGS with H. pylori or cytokine-rich supernatants from H. pylori-activated PBMC resulted in up-regulation of expression of CD44 and ICAM-1 on AGS cells. These data suggest that H. pylori directly and indirectly through inflammatory cytokines may contribute to alternations in adhesion molecule expression on gastric epithelial cells. This may be of pathological significance in H. pylori-associated gastric mucosal inflammation and carcinogenesis.

Healing of gastric body ulcer with gastroprotective versus antisecretory treatment

The aim of this study was to compare the healing effect of a gastroprotective agent and antisecretory drugs in gastric body ulcer where failure of the mucosal defense might be an important factor. Eighty-five patients with benign gastric ulcer were divided into four groups: treated with antacids (I), cimetidine (II), ranitidine (III), and colloidal bismuth subcitrate (De-Nol) (IV). Endoscopically confirmed complete healing was achieved in 57, 61, and 63% in groups I, II, and III, respectively, and in 88% in group IV (P < 0.05). Gastric secretion did not change significantly. Relapses during the next three years occurred several times more frequently in groups I, II, and III than in group IV. Helicobacter pylori was positive in about half the relapsing patients in groups I, II, and III but negative in those of group IV. It is concluded that De-Nol treatment of gastric body ulcer was more efficient than antisecretory drugs both initially and in reducing relapses.

Isolation of the Helicobacter pylori recA gene and involvement of the recA region in resistance to low pH

To understand the potential roles of the important DNA repair protein RecA in Helicobacter pylori pathogenesis, we cloned the recA gene from H. pylori 84-183. Degenerate PCR primers based on conserved RecA protein regions were used to amplify a portion of H. pylori recA, which was used as a probe to isolate the full-length recA gene from H. pylori genomic libraries. The H. pylori recA gene encoded a protein of 347 amino acids with a molecular mass of 37.6 kDa. As expected, H. pylori RecA was highly similar to other RecA proteins and most closely resembled that of Campylobacter jejuni (75% identity). Immediately downstream of recA was an open reading frame whose predicted product showed 58% identity to the Bacillus subtilis enolase protein. recA and eno were disrupted in H. pylori 84-183 by insertion of antibiotic resistance genes. Reverse transcription-PCR demonstrated that recA and eno were cotranscribed and that insertion of the kanamycin resistance gene into recA had polar effects on expression of the downstream eno. The H. pylori recA mutants were severely impaired in their ability to survive treatment with UV light and methyl methanesulfonate and with the antimicrobial agents ciprofloxacin and metronidazole. The eno mutant had sensitivities to UV light and metronidazole intermediate to those of wild-type and recA strains, suggesting that truncation of the recA-eno transcript resulted in lowered recA expression. For survival at low pH, a recA mutant was approximately 10-fold more sensitive than strain 84-183, while the eno mutant demonstrated intermediate susceptibility. This difference occurred in the presence or absence of urea, implying the involvement of a gene in the recA region in an acid resistance mechanism distinct from that mediated by urease.