Expression profiling of responses of Helicobacter pylori to acidic media

Abstract

metaplasia ([M) in patients from a high risk area of GC. Methods: We studied 101 patients who underwent endoscopy with (48 cases) or without (53 controls) GA and [M. All patients signed a valid consent, and blood samples were obtained prior endoscopy. Gastric biopsies were obtained from the antrum, body, and fundns. H. pylori culture was intended in all patients, from antrum and body biopsy samples. DNA was extracted and purified from one of the antrum biopsy for PCR analysis of several bacterial genes, including glmM, vacA and cagA as previously described (PNAS, 2002;99:15107-15111). Histology was performed for a single pathologist, who scored one biopsy for each of the three sites selected according to the Sidney system. Results: We found similar proportions of H. pylon positive individuals based on histology (81.1%) and serology (77.2%) in the whole group. Presence of GA and/ or IM was not associated with the presence of cagA+ strains (p=0.71), but was associated with infection by vacA sl strains (p = 0.03). H. pylon was more prevalent in patients without than in patients with GA or IM, when the status was defined by a serological criteria in combination with PCR amplification of glmM gene (p<0.01). No difference in age was observed between H. pylon positive and H. pylon negative patients; however, as expected, patients with GA or IM were older than patients without GA or IM (p<0.01), independently of H. pylori status. Conclusions: H. pylori prevalence was universally high in this community. Infection by vacA sl strains ks a risk factor for GA or IM, which are progression steps towards GC. Patients with intact gastric mucosa are more likely to be H. pylori positive, confirming that the progression in the gastric damage (GA and IM) modified the microenvironment for H. pylori.