부산대학교 도서관

[CD4.sup.+] T helper lymphocytes that express interleukin-17 ([T.sub.H]17 cells) have critical roles in mouse models of autoimmunity, and there is mounting evidence that they also influence inflammatory processes in humans. Genome-wide association studies in humans have linked genes involved in [T.sub.H]17 cell differentiation and function with susceptibility to Crohn's disease, rheumatoid arthritis and psoriasis (1-3). Thus, the pathway towards differentiation of [T.sub.H]17 cells and, perhaps, of related innate lymphoid cells with similar effector functions (4,5), is an attractive target for therapeutic applications. Mouse and human [T.sub.H]17 cells are distinguished by expression of the retinoic acid receptor-related orphan nuclear receptor RORγt, which is required for induction of IL-17 transcription and for the manifestation of TH17-dependent autoimmune disease in mice (6). By performing a chemical screen with an insect cell-based reporter system, we identified the cardiac glycoside digoxin as a specific inhibitor of RORγt transcriptional activity. Digoxin inhibited murine [T.sub.H]17 cell differentiation without affecting differentiation of other T cell lineages and was effective in delaying the onset and reducing the severity of autoimmune disease in mice. At high concentrations, digoxin is toxic for human cells, but non-toxic synthetic derivatives 20,22-dihydrodigoxin-21,23-diol and digoxin21-salicylidene specifically inhibited induction of IL-17 in human [CD4.sup.+] T cells. Using these small-molecule compounds, we demonstrate that RORγt is important for the maintenance of IL-17 expression in mouse and human effector T cells. These data indicate that derivatives of digoxin can be used as chemical templates for the development of RORγt-targeted therapeutic agents that attenuate inflammatory lymphocyte function and autoimmune disease.
To identify small molecules that specifically inhibit transcriptional activity of RORγ and RORγt isoforms, we prepared Drosophila S2 cells stably expressing fusions of the GAL4 DNA-binding domain (DBD) and the [...]