title: Rationally designed inhibitor targeting antigen-trimming aminopeptidases enhances antigen presentation and cytotoxic T-cell responses.
abstract: Intracellular aminopeptidases endoplasmic reticulum aminopeptidases 1 and 2 (ERAP1 and ERAP2), and as well as insulin-regulated aminopeptidase (IRAP) process antigenic epitope precursors for loading onto MHC class I molecules and regulate the adaptive immune response. Their activity greatly affects the antigenic peptide repertoire presented to cytotoxic T lymphocytes and as a result can regulate cytotoxic cellular responses contributing to autoimmunity or immune evasion by viruses and cancer cells. Therefore, pharmacological regulation of their activity is a promising avenue for modulating the adaptive immune response with possible applications in controlling autoimmunity, in boosting immune responses to pathogens, and in cancer immunotherapy. In this study we exploited recent structural and biochemical analysis of ERAP1 and ERAP2 to design and develop phosphinic pseudopeptide transition state analogs that can inhibit this family of enzymes with nM affinity. X-ray crystallographic analysis of one such inhibitor in complex with ERAP2 validated our design, revealing a canonical mode of binding in the active site of the enzyme, and highlighted the importance of the S2' pocket for achieving inhibitor potency. Antigen processing and presentation assays in HeLa and murine colon carcinoma (CT26) cells showed that these inhibitors induce increased cell-surface antigen presentation of transfected and endogenous antigens and enhance cytotoxic T-cell responses, indicating that these enzymes primarily destroy epitopes in those systems. This class of inhibitors constitutes a promising tool for controlling the cellular adaptive immune response in humans by modulating the antigen processing and presentation pathway.
authors.affiliation: National Center for Scientific Research Demokritos, Agia Paraskevi 15310, Greece.
authors.forename: Efthalia
authors.initials: E
authors.lastname: Zervoudi
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Saridakis
authors.forename: James R
authors.initials: JR
authors.lastname: Birtley
authors.forename: Sergey S
authors.initials: SS
authors.lastname: Seregin
authors.forename: Emma
authors.initials: E
authors.lastname: Reeves
authors.forename: Paraskevi
authors.initials: P
authors.lastname: Kokkala
authors.forename: Yasser A
authors.initials: YA
authors.lastname: Aldhamen
authors.forename: Andrea
authors.initials: A
authors.lastname: Amalfitano
authors.forename: Irene M
authors.initials: IM
authors.lastname: Mavridis
authors.forename: Edward
authors.initials: E
authors.lastname: James
authors.forename: Dimitris
authors.initials: D
authors.lastname: Georgiadis
authors.forename: Efstratios
authors.initials: E
authors.lastname: Stratikos
mesh_terms: D000626:Aminopeptidases / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D000818:Animals; D017951:Antigen Presentation / Q000187:drug effects / Q000276:immunology*; D001665:Binding Sites / Q000276:immunology; D045744:Cell Line, Tumor; D018360:Crystallography, X-Ray; D010122:Cystinyl Aminopeptidase / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D015778:Minor Histocompatibility Antigens; D008958:Models, Molecular; D015394:Molecular Structure; D010721:Phosphinic Acids; D015202:Protein Engineering; D013602:T-Lymphocytes, Cytotoxic / Q000187:drug effects / Q000276:immunology*
chemical_list: D015778:Minor Histocompatibility Antigens; D010721:Phosphinic Acids; D000626:Aminopeptidases; C464841:ERAP1 protein, human; C503944:ERAP2 protein, human; D010122:Cystinyl Aminopeptidase; C105964:leucyl-cystinyl aminopeptidase
keywords: adaptive immunity; kinetics; major histocompatibility molecules; molecular structure; specificity