Expression data from stomach biopsies with gastritis and intestinal metaplasia lesions

Helicobacter pylori is a well-recognized bacterium associated with the development of several histopathological lesions in the stomach. The chronic infection produces an inflammatory lesion known as gastritis. This lesion can later progress to more serious lesions such as intestinal metaplasia. Some attempts in the transcriptome of these conditions have been made; these however, have yielded limited information. Given the potential of high-throughput technologies for understanding biological processes altered and in the description of biomarkers of disease, we performed a genome-wide gene expression analysis in gastric biopsies. The aim of this study was to describe the altered molecular mechanism and potential biomarkers of follicular gastritis, chronic gastritis and intestinal metaplasia, through the identification of characteristic gene expression profiles in each histopathological lesion. The exploratory set comprised twenty-one biopsies from patients with follicular gastritis (n=7), chronic gastritis (n=7), and intestinal metaplasia (n=7), which were analyzed by whole-genome gene expression microarrays. The enrichment analyses and functional annotation of genes using computational tools were performed. The bioinformatics data of the same 21 biopsies were validated by real time PCR analysis while 79 FFPE samples were analyzed by immunohistochemistry. Gene expression analyses showed profiles for each histopathological lesion. Follicular gastritis had an expression profile with marked enrichment of immunologically-related genes. In contrast, chronic gastritis was characterized by a deregulation of mitochondrial-related genes and a down regulation of genes associated with protection against oxidative stress. Meanwhile, intestinal metaplasia showed an over expression of gastrointestinal stem cell markers and molecules related to RNA metabolism. Our results provide a comprehensive and reliable gene expression analysis of follicular gastritis, chronic gastritis and intestinal metaplasia disorders. The gene expression patterns described established a clear difference between the three pathologies studied and allowed the identification of several potential biomarkers for each histological change. RNA from 21 biopsies from patients with follicular gastritis, chronic gastritis and intestinal metaplasia were analyzed by microarrays. Gene Set Enrichment Analysis, and differential expression analysis with subsequent functional annotation was performed for each group of histological lesions.