Gene expression alterations in inflamed and unaffected colon mucosa from patients with mild inflammatory bowel disease

Abstract

An endoscopic examination is currently the most reliable method for monitoring disease activity in patients with inflammatory bowel disease (IBD). However, endoscopic evaluations are unable to detect mucosal inflammation at the earliest stages. The present study aimed to evaluate the molecular profiles of inflamed and unaffected colon mucosa from patients with mild Crohn's disease (CD) and ulcerative colitis (UC), in order to identify a more sensitive method for monitoring mucosal impairment. Patients were recruited and colon biopsies from the inflamed and the normal-appearing mucosa of patients with mild IBD were obtained by colonoscopy. Gene expression analysis was performed using microarrays, after which Gene Ontology and clustering were performed using bioinformatics. In addition, the levels of inflammatory cytokines were analyzed by reverse transcription-quantitative polymerase chain reaction. A total of 620 genes in the inflamed and 210 genes in the unaffected colon mucosa with at least a 3-fold change, as compared with healthy controls, were detected in patients with mild CD, and 339 genes in the inflamed and 483 genes in the unaffected colon mucosa were detected in patients with mild UC. Heat mapping demonstrated a similarity in the gene alteration patterns, and altered transcripts overlapped, between the inflamed and unaffected colon mucosa. Interferon-γ and interleukin-17 mRNA levels were comparably elevated in the inflamed and unaffected colon mucosa from patients with IBD. Marked gene expression alterations were detected in the inflamed and unaffected colon mucosa from patients with mild IBD, and these showed marked similarity and overlap between the two groups. The results of the present study suggested that inflammation was not limited to the endoscopic lesions and that gene expression profiling may be considered a sensitive tool for monitoring mucosal inflammation, predicting relapses and optimizing therapeutic strategies for patients with IBD.