Effects of Helicobacter pylori colonisation on the adherent gastric mucus barrier

Effects of Helicobacter pylori infection on mucin expression in gastric carcinoma and pericancerous tissues

BACKGROUND

Helicobacter pylori infection is one of the major causes of human gastric carcinoma and can disturb the gastric mucosa barrier. Mucins have not only lubricating and protecting functions, but are also related to signal transduction, turnover of gastric epithelium and carcinogenesis of gastric mucosa. The aim of this study was to investigate the relationship between H. pylori infection and aberrant mucin expression in patients with gastric carcinoma.

METHODS

H. pylori infection was diagnosed by the Warthin-Starry staining method. Different kinds of mucins were detected using an immunohistochemical method.

RESULTS

Of 46 patients with gastric carcinoma, there were 26 patients who had H. pylori infection (56.5%). Of 21 pericancerous mucosas from the H. pylori-positive patients, 14 had MUC2 expression (66.7%), seven had strong MUC1 expression (+ + +) (33.7%), seven had strong MUC6 expression (+ + +) (33.3%), and five had strong MUC5AC expression (+ + +) (23.8%). In contrast, only six of 18 H. pylori-negative pericancerous mucosas had MUC2 expression (33.3%) (P < 0.05 compared with H. pylori-positive pericancerous mucosas), 12 had strong MUC1 expression (+ + +) in 16 H. pylori-negative pericancerous mucosas (75%) (P < 0.05), 11 had strong MUC6 expression (+ + +) in 16 H. pylori-negative pericancerous mucosas (68.8%) (P < 0.05), and 10 had strong MUC5AC expression (+ + +) in 14 H. pylori-negative pericancerous mucosas (71.4%) (P < 0.01). Of the H. pylori-positive cancerous tissues, 50% (13/26) had MUC1 expression and 38.5% (10/26) had MUC6 expression. In comparison, of the H. pylori-negative cancerous tissues, 80% (16/20) had MUC1 expression (P < 0.05) and 80% (16/20) had MUC6 expression (P < 0.01).

CONCLUSIONS

The results indicate that H. pylori infection can alter the expression of some mucin genes in pericancerous mucosa and cancerous tissues of gastric carcinoma, then destroy the gastric mucosa barrier.

Effects of cagA+ and cagA- strains of Helicobacter pylori on the human gastric mucus layer thickness

BACKGROUND

Infection with cytotoxin-associated gene A (cagA) Helicobacter pylori is associated with severe gastric diseases, with contradictory views being expressed concerning the effect of H. pylori on the gastric mucus thickness. The aim of the present study was to differentiate between the effect of cagA+ and cagA- strains on gastric mucus thickness.

METHODS

Ninety-nine patients without peptic ulcers who were not on medication were randomly recruited from consecutive endoscopy clinics: six biopsies (five antral, one body) were obtained from each patient. Cryostat sections (18 microm) were cut and stained using the modified periodic acid-Schiff/Alcian blue technique. Mucus thickness was measured using computer-assisted light microscopy. The H. pylori status was assessed by histology, Campylobacter-like organism (CLO)test and culture, and cagA+ status determined by polymerase chain reaction (PCR).

RESULTS

There was no significant difference (P = 0.784) in mean mucus thickness between cagA+ (52.7 +/- 1.2 microm, n = 10), cagA- (46.6 +/- 1.1 microm, n = 18) or H. pylori-negative patients (51.3 +/- 1.1 microm, n = 30). In cagA- patients, mucus thickness was significantly reduced with increased H. pylori colonization density, Spearman (r(s)) = -0.805, P < 0.0001. In contrast, in cagA+ patients there was a weak positive, but not significant, association between mucus thickness and H. pylori colonization density, r(s) = 0.333, P = 0.381.

CONCLUSIONS

The human gastric mucus thickness is not affected by infection with cagA+ or cagA- strains of H. pylori compared with uninfected. Although a trend of increased mucus thickness with cagA+ infection was observed.