| Project 3 |
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Intrinsic regulation of Th1-mediated chronic immune responsesProf. Radbruch (first supervisor), Prof. Burmester (second supervisor), Dr. Chang (mentor); DRFZ and Charité pathogenic role in chronic-inflammatory disorders. Antigenic stimulation of Th cells elicits a local inflammatory response that facilitates the rapid clearance of the antigen. Autoantigens, however, cannot be cleared. Th cells recognizing those antigens may represent a principal mechanism by which an inflammation may become chronic. By analysis of the global gene expression using an in vitro model of acutely and chronically activated Th cells we have identified genes which in face of the sustained presence of antigen may control the longevity of Th cells, regulate their functionality and/or mark pathogenic cells. One of the genes, twist1, identified to be highly expressed in repeatedly stimulated Th1 cells has been characterized further. We have demonstrated that twist1 downregulates the effector function of Th1 cells and limits inflammation. The detection of twist1 exclusively in effector memory Th cells at the site of inflammation in patients with autoimmune diseases, hints at a role for twist1 in the chronification of inflammation. A second gene, also upregulated in Th1 cells is also currently under investigation. The aim of the project will be to study the role of both genes for the persistence and function of pathogenic Th1 cells in murine models of chronic inflammation, primarily the ovalbumin-induced arthritis model and colitis model. We have generated conditional twist1 knock-out mice in which the twist1 promoter and first exon is flanked by loxP sites. T cells from these mice will be analyzed using tat-Cre fusion protein, in in vitro settings. These mice are also crossed to transgenic mice expressing Cre-recombinase under the cd4 promoter to specifically knock-out twist1 expression in CD4+ Th cells allowing the analysis of the role of twist1 in vivo. The underlying molecular mechanism of the regulation will be studied through identification of interaction partners and target genes with established biochemical and molecular biological methods |
