Targeted inhibition of EPAS1-driven IL-31 production by a small-molecule compound.

ABSTRACTS Background IL-31 is a major pruritogen associated with atopic dermatitis (AD). Although a specific antibody for IL-31 receptor has been shown to alleviate pruritus in patients with AD, therapeutic approaches to inhibit IL-31 production remain unexploited. IL-31 production by helper T cells critically depends on the transcription factor EPAS1, which mediates IL31 promoter activation in collaboration with SP1. Objective We aimed at developing small-molecule inhibitors that selectively block IL-31 production by helper T cells. Methods We generated the reporter cell line that inducibly expressed EPAS1 in the presence of doxycycline to mediate Il31 promoter activation, and screened 9,600 chemical compounds. The selected compounds were further examined using helper T cells from a spontaneous mouse model of AD and those from patients with AD. Results We have identified 4-(2-(4-isopropylbenzylidene)hydrazineyl)benzoic acid (IPHBA) as an inhibitor of IL-31 induction. Although IPHBA did not affect non-specific T cell proliferation, IPHBA inhibited antigen–induced IL-31 production by helper T cells from both an AD mouse model and AD patients, without affecting other cytokine productions and hypoxic responses. In line with this, itch responses induced by adoptive transfer of IL-31-producing helper T cells were attenuated when mice were orally treated with IPHBA. Mechanistically, IPHBA inhibited association between EPAS1 and SP1, resulting in defective recruitment of both transcription factors to the specific sites of IL31 promoter. We also determined the structure–activity relationship of IPHBA by synthesizing and analyzing 201 analog compounds. Conclusion IPHBA could be a potential drug lead to inhibit EPAS1-driven IL-31 production.