Crohn's Colitis: Development of a multiplex gene expression assay comparing mRNA levels of susceptibility genes

Summary Crohn's disease (CD) is a multifactorial immunologically mediated disease. In this study we explored, for the first time, the efficacy of the Multiplex Gene Assay technology for detecting mRNA expression profile of 24 selected CD related genes in endoscopic biopsies and surgical specimens from CD patients with colonic localization of the disease. The polymorphisms of genes most frequently associated with CD were also analysed in DNA samples from the same patients. The analysis of endoscopic samples showed increased expression of 7 genes in inflamed mucosa compared to non-inflamed mucosa and suggests the activation of the autophagy process and of a Th17 adaptive response. The analysis of surgical specimens showed increased expression of 16 genes in inflamed tissue compared to non-inflamed internal controls and revealed the activation of immune-adaptive Th17 response in association with a Th1 response. Furthermore, an increased expression of genes involved in ionic transport and signal transduction was found in inflamed mucosa compared to non-inflamed internal controls. This study confirms the activation of Th17 and Th1 adaptive-immune response also in colonic CD. It should be stressed that these responses have been disclosed in biopsy tissue, while only Th17 differentiation is revealed in endoscopic tissue. Interestingly, the polymorphisms analysis revealed that a homozygous genotype is associated to a more complicated clinical course.