The gene expression profile of cardia intestinal metaplasia is similar to that of Barrett's esophagus, not gastric intestinal metaplasia

The etiology and significance of cardia intestinal metaplasia (CIM) is disputed. CIM may represent a form of Barrett's esophagus due to reflux or could reflect generalized gastric intestinal metaplasia due to Helicobacter pylori. The aim of this study was to utilize gene expression data to compare CIM to Barrett's and gastric intestinal metaplasia. Endoscopic biopsies were classified by endoscopic and histologic criteria as CIM (n= 33), Barrett's (n= 25), or gastric intestinal metaplasia of the antrum or body (n= 18). The squamocolumnar and gastroesophageal junctions were aligned in CIM patients and patients with diffuse gastric intestinal metaplasia were excluded. H. pylori was tested for in the biopsies of all patients. After laser-capture microdissection, quantitative reverse transcription-polymerase chain reaction (RT-PCR) was used to measure the mRNA expression of a panel of nine genes that has been shown to differentiate Barrett's from other foregut mucosa. Cluster analysis with linear discriminant analysis of the expression data was used to classify each sample into groups based solely on similarity of gene expression. Cluster analysis was performed for three groups (CIM vs. Barrett's vs. gastric intestinal metaplasia) and two groups (CIM + Barrett's vs. gastric intestinal metaplasia). There was no difference in H. pylori infection among groups (P= 0.66). Clustering into three groups resulted in frequent misclassification between CIM and Barrett's while misclassification of gastric intestinal metaplasia was uncommon. The CIM and Barrett's groups were then combined for two group clustering and linear discriminant analysis correctly predicted 95% of CIM and Barrett's samples and 83% of gastric intestinal metaplasia samples based on gene expression alone. In conclusion, the gene expression profiles of CIM and Barrett's esophagus were similar in 95% of biopsies and differed significantly from that of gastric intestinal metaplasia. The indistinguishable gene expression profile of CIM and BE suggests that they may share a common etiology in the majority of patients with a similar biology, and calls into question the perception that CIM is an innocuous process.