Pathogenetic role of the tyrosine-phosphorylated CagA EPIYA sequence of Helicobacter pylori in histological gastritis in Japanese patients.

Background: Helicobacter pylori (H. pylori) CagA protein plays an important role in the clinical outcome of gastritis treatment. Tyrosine phosphorylated Glu-Pro-Ile-Tyr-Ala motif in CagA (CagA-P) plays a critical role in the morphological transformation of cells.

Aim: We examine the relationship between serum titer of anti-CagA-P antibody and gastric inflammation as well as the status of the CagA-P expression in gastric mucosa.

Methods: Fasting sera from 127 dyspeptic patients were collected, and anti-CagA-P antibody was evaluated. Gastric biopsy specimens were collected and histological gastritis was evaluated. We investigate the expression of CagA-P in human gastric mucosa by Western blotting and immunohistochemistry.

Results: The titers of anti-CagA-P antibodies in the sera of H. pylori (+) patients were significantly higher than those of H. pylori (-) patients (P < 0.001). In 107 H. pylori (+) patients, anti-CagA-P titer was statistically higher in patients with high gastritis scores in the corpus than in those with low scores (P < 0.05). CagA-P expression was detected in the foveolar epithelium of the H. pylori infected gastric mucosa.

Conclusion: CagA-P is an antigen-peptide against the host, and serum titer of anti-CagA-P antibody may be a new marker for gastritis in the corpus.