Corilagin regulates antigen processing and presentation by directly binding to inhibit ERAP1.

ERAP1 is a critical aminopeptidase that acts as the final "editor" of endogenous antigen peptides in the endoplasmic reticulum, playing a key role in the MHC-I-mediated antigen processing and presentation pathway. It has become a novel target for a broad class of severe autoimmune diseases, referred to as "MHC-I-opathy," as well as for tumor immune evasion. Here, we report the discovery of a food-derived natural product inhibitor, Corilagin, with a novel scaffold that directly interacts with ERAP1, identified through high-throughput screening.