Inhibiting amyloid-β cytotoxicity through its interaction with the cell surface receptor LilrB2 by structure-based design

Inhibiting the interaction between amyloid-beta (A beta) and a neuronal cell surface receptor, LilrB2, has been suggested as a potential route for treating Alzheimer's disease. Supporting this approach, Alzheimer's-like symptoms are reduced in mouse models following genetic depletion of the LilrB2 homologue. In its pathogenic, oligomeric state, A beta binds to LilrB2, triggering a pathway to synaptic loss. Here we identify the LilrB2 binding moieties of A beta ((16)KLVFFA(21)) and identify its binding site on LilrB2 from a crystal structure of LilrB2 immunoglobulin domains D1D2 complexed to small molecules that mimic phenylalanine residues. In this structure, we observed two pockets that can accommodate the phenylalanine side chains of KLVFFA. These pockets were confirmed to be (16)KLVFFA(21) binding sites by mutagenesis. Rosetta docking revealed a plausible geometry for the A beta-LilrB2 complex and assisted with the structure-guided selection of small molecule inhibitors. These molecules inhibit A beta-LilrB2 interactions in vitro and on the cell surface and reduce A beta cytotoxicity, which suggests these inhibitors are potential therapeutic leads against Alzheimer's disease.