Design Of Peptide Inhibitors And Peptide-functioncalized Nanoparticles For The Inhibition Of Amyloid β Protein Aggregation

The misfolding and aggregation of protein can cause various amyloidosis. Amyloid-β protein is pathologically linked to Alzheimer’s disease(AD). Hence, the inhibition of Aβ aggregation is essential for the prevention and treatment of AD. In recent years, researches have focused on nano-inhibitors which serve as targeted agents towards AD. However, due to the poor understanding of NP-amyloid interactions, the development of nano-inhibitors of inhibiting Aβ fibrillogenesis has posed significant challenges.To improve the inhibitory effect of existing peptide or nano-inhibitors towards Aβ aggregation, and the understanding of NP-Aβ interactions, we first designed peptide inhibitors, Ac-LVFFARK-NH2(LK7) and Ac-KRGLVFFARK-NH2(KK10) and then examined their inhibitory effects on Aβ42 aggregation. The results revealed that LK7 and KK10 effectively inhibited Aβ42 fibrillogenesis and induced amorphous aggregates. LK7 and KK10 could self-aggregate into fibrils. Moreover, they could not inhibit Aβ42 induced cytotoxicity, meanwhile the self-aggregates of LK7 exhibited additional cytotoxicity.In order to prevent the defect of the peptide inhibitors, the peptides was then conjugated to the surface of poly(lactic-co-glycolic acid)(PLGA) nanoparticles(NPs) to fabricate into nano-inhibitors. Among that, LK7@PLGA-NPs showed remarkable inhibitory capability against Aβ42 aggregation and significantly alleviated its cytotoxicity at a low LK7@PLGA-NPs concentration of 20 μg/m L. It is considered that several synergetic effects contributed to the strong inhibitory ability of LK7@PLGA-NPs, including the enhanced interactions between Aβ42 and LK7@PLGA-NPs by inhibiting LK7 self-assembly, restricting conformational changes of Aβ42, and thus redirecting Aβ42 aggregation into unstructured, off-pathway aggregates. The dosage of LK7 ligands on LK7@PLGA-NPs was 1/69 of free LK7 peptide when they showed the same inhibitory effects.In order to analysis the synergetic effects generated by the conjugation of peptide to NPs, two typical peptide inhibitor, LPFFD and VVIA were employed to fabricate chimeric peptide inhibitors and peptide-functionalized GNPs. The results revealed that the alignments and conjugation sites have influenced the inhibitory effect to ABβ42 aggregation. Among peptide-functionalized GNPs, VCD10@GNPs exhibited superiority in the inhibitory effect against Aβ42 aggregation and cytotoxicity. Based on the experimental results, we proposed that the hydrophobic residues and negative charged residues exposed in NP-solution interface, as well as the unique conformation formed by the restrict peptide ligands, were critical to the inhibitory effect of nano-inhibitors.The study showed that peptide-functionalized NPs not only prevented the self-aggregation of peptide and NPs, but also greatly improved the inhibitory effect against Aβ aggregation and cytotoxicity. Especially VCD10@GNPs, which showed high inhibitory efficient and capability to penetrate blood-brain barrier, has the potential to become drug candidate to the treatment and prevention of AD.