The role of the transcription factor T-bet in inflammatory bowel disease. (360G-Wellcome-088747_Z_09_Z)

Mounting evidence indicates that the inflammatory bowel diseases (IBD), ulcerative colitis (UC) and Crohn's disease (CD) result from failed immunological tolerance towards gut microbes, leading to chronic T cell-mediated inflammation. Interactions between T-cells and dendritic cells (DCs) are undoubtedly critical regulators of gut inflammation. We have recently reported a preclinical model of colitis where selective absence of the transcription factor T-bet in DCs results in spontaneous, TNF-alp ha dependent colitis with striking similarities to human UC. The question addressed by this study is whether these preclinical mechanistic pathways are relevant and translatable to human disease. We will define T-bet expression in lamina propria DCs from IBD patients and controls and determine its relationship to intracellular TNF-alpha expression. Using multicolour flow cytometry we will simultaneously define the phenotypes of DCs, T-cells and NK-cells, with respect to cell surface, intracell ular cytokine and transcription factors at an individual cell level. Using cutting edge phosphoflow analyses we will determine the role of transcription factor phosphorylation in conferring an inflammatory phenotype to these cell populations. We will manipulate T-bet expression in DCs to determine whether this alters their co-stimulatory capacity or influences their ability to drive effector T-cell function towards an inflammatory or regulatory phenotype.