Transcriptome meta-analysis identifies immune signature comprising of RNA binding proteins in ulcerative colitis patients

Abstract

Ulcerative colitis (UC) is a persistent inflammatory illness, which is clinically categorised as Inflammatory bowel disease (IBD), affecting millions of people worldwide. The precise cause behind the pathology of the disease remains unknown. However, the involvement of multiple factors including genetic predisposition, immunological deregulations, microbiota imbalance, and environmental triggers has been suggested. Amongst all these factors, the over-active immunological response reported in UC patients seems to be a promising target for therapy. Moreover, identification of gene signatures associated with disease onset and progression would help in better understanding of the molecular mechanisms involved in the disease pathogenesis. Here, we have conducted meta-analysis of gene expression profiles of UC patient microarray datasets accessible in public databases and further validated the in-silico findings in UC patients' blood samples. Our study reveals that UC pathogenesis perturbs expression of several inflammatory genes. In addition, we report a novel gene signature comprising of TIA1 (T cell restricted intracellular antigen) and TIAR (TIA1 related protein; also known as TIAL1), which were found to be significantly downregulated in UC patients. TIA1 and TIAR are RNA-binding proteins (RBPs), which function as a translational represser by binding to ARE sequences in the 3' UTR of mRNAs encoding inflammatory mediators including cytokines. Our findings demonstrate that deletion of TIAR using gene specific siRNAs in-vitro results in enhanced production of inflammatory cytokine IL-1β. In conclusion, the findings of this study reveal that down regulation of TIA1/TIAR genes could be responsible for UC associated inflammation. This study highlights the usefulness of the meta-analysis approach in the identification of unique gene signatures that might deliver mechanistic insights into UC pathogenesis and possibly assist in discovery of prognostic markers and therapeutic interventions.

Keywords: IBD; Meta-analysis; RNA-binding proteins; TIA1; TIAR; Ulcerative colitis.