Small-Molecule RORγt Antagonists Inhibit T Helper 17 Cell Transcriptional Network by Divergent Mechanisms

We identified three retinoid-related orphan receptor gamma t (ROR gamma t)-specific inhibitors that suppress T helper 17 (Th17) cell responses, including Th17-cell-mediated autoimmune disease. We systemically characterized ROR gamma t binding in the presence and absence of drugs with corresponding whole-genome transcriptome sequencing. ROR gamma t acts as a direct activator of Th17 cell signature genes and a direct repressor of signature genes from other T cell lineages; its strongest transcriptional effects are on cis-regulatory sites containing the ROR alpha binding motif. ROR gamma t is central in a densely interconnected regulatory network that shapes the balance of T cell differentiation. Here, the three inhibitors modulated the ROR gamma t-dependent transcriptional network to varying extents and through distinct mechanisms. Whereas one inhibitor displaced ROR gamma t from its target loci, the other two inhibitors affected transcription predominantly without removing DNA binding. Our work illustrates the power of a system-scale analysis of transcriptional regulation to characterize potential therapeutic compounds that inhibit pathogenic Th17 cells and suppress autoimmunity.