| Popis: |
Therapeutic approaches to fight Alzheimer's Disease include anti-A? peptide antibodies and secretase inhibitors or modulators and aim to either prevent or reduce amyloidosis. Secretase inhibitors are considered to reduce the de novo production of A?, but efficiency is limited due to restricted passage of therapeutic molecules over the blood-brain barrier (BBB). The Brain Shuttle (BS) technology based on Transferrin Receptor (TfR)-mediated transport is capable of shuttling large molecules over the BBB into the brain. We designed BACE1 specific peptide inhibitors with varying lipid terminal modifications, and ligated them to the BS via a sortase linker. A 1.82? resolution crystal structure of BACE1 ectodomain in complex with a dual, ortho-exosite peptide inhibitor shows that this compound binds with both arms to the same protein. We performed a study comparing these BACE1 inhibitor peptides in vivo. BACE1 inhibition led to a significant time- and dose-dependent decrease in plasma A?, and only after ligating the inhibitory peptides to the BS, to a significant decrease in brain A? levels. BACE1 inhibition over time was most significant in brain and plasma if the molecule contained a palmitylated terminus. Changing the terminus to cholesterol reduced the BACE1 inhibitor peptide efficacy in vivo, even though in vitro gathered cell IC50 data suggested otherwise. A lipid-free BS-BACE1 inhibitor conjugate also led to a 40% A? decrease in brain levels at 24 hrs in wt mice. Our results demonstrate that the BS is key for brain exposure following systemic administration and paves the way for BACE1 peptide inhibitors with optimized pharmacophores to achieve superior potency and selectivity. |
