Mo1577 Different Protein Expression and Genes Patterns of Helicobater Pylori in Pathological Disorders of the Gastric Mucosa

Abstract

Background and aim: One goal of Helicobacter pylori (HP) research is the individuation of bacterial markers of gastric cancer (GC). We accomplished a proteomic and genotypic pilot approach to discover bacterial biomarkers by comparing HP isolated from GC and precancerous lesions (duodenal ulcers, DU, and autoimmune atrophic gastritis, AAG). Material and methods: A total of 35 HP strains isolated from antrum and/or corpus of patients with HP-diseases (14 GC; 4 AAG; 8 DU) were investigated. Protein of HP colonies grown from cultured gastric biopsies were extracted and submitted to comparative ‘two-dimensional difference in gel electrophoresis, 2D-DIGE' followed by Decyder statistics analysis and protein identification by MALDI-Tof/Ms spectrometry. DNA was extracted from a total of 10 single colonies/patient and tested for virulence factors coding genes (CagA, CagE, VirB11) of Cag Pathogenicity Island (CagPAI) by PCR. For both proteomics and genetics, HP strains were categorized based on their tissue disease localization (corpo versus antro) and gastric mucosa pathologies. Results: Little genetic heterogeneity was shown in DUand GC-derived HP strains, with only CagE deletions found in 6/19 GC. AAG-HP showed a substantial deletion of all the 3 genes. Protein maps specifically clusterized for gastric diseases but not for tissue localization, the GC group being discriminated from the others by the principal component analysis (ANOVA p<0.0001). A total of 29 protein spots were found to be differentially expressed. In particular, a subset of proteins (i.g. catalases, alkyhydroxyperoxide reductase, isocitrate dehydrogenase and S-adenosylmethionine synthase) was identified as specifically up-regulated in DU. Conclusions: Although, HP strains are difficult to be isolated from AAG (4/20 pts), in the only AAG genetic analyses evidenced a deletion of CagPAI, thus suggesting a decrease in HP growth with a prevalence of less virulent strains. Therefore, the progressive model of AAG to GC seems independent of HP virulence in our series. By converse, some important proteins were specifically found associated with GC. Previously, the same proteins were reported in different papers as single potential biomarkers for GC and DU. Our data strongly suggest their overall involvement in HP-related gastric disorders.