Natural Compound 2,2′,4′-Trihydroxychalcone Suppresses T Helper 17 Cell Differentiation and Disease Progression by Inhibiting Retinoid-Related Orphan Receptor Gamma T

Retinoid-related orphan receptor γt (RORγt), a vital transcription factor for the differentiation of the pro-inflammatory Th17 cells, is essential to the inflammatory response and pathological process mediated by Th17 cells. Pharmacological inhibition of the nuclear receptor RORγt provides novel immunomodulators for treating Th17-driven autoimmune diseases and organ transplant rejection. Here, we identified 2,2′,4′-trihydroxychalcone (TDC), a natural chalcone derivant, binds directly to the ligand binding domain (LBD) of RORγt and inhibited its transcriptional activation activity. Using three mice models of Th17-related diseases, it was found that the administration of TDC effectively alleviated the disease development of experimental autoimmune encephalomyelitis (EAE), experimental colitis, and skin allograft rejection. Collectively, these results demonstrated TDC targeting RORγt to suppress Th17 cell polarization, as well as its activity, thus, indicating the potential of this compound in treating of Th17-related autoimmune disorders and organ transplant rejection disorders.