Optimization of d-Peptides for Aβ Monomer Binding Specificity Enhances Their Potential to Eliminate Toxic Aβ Oligomers

Abstract

Amyloid-beta (Aβ) oligomers are thought to be causative for the development and progression of Alzheimer's disease (AD). Starting from the Aβ oligomer eliminating d-enantiomeric peptide D3, we developed and applied a two-step procedure based on peptide microarrays to identify D3 derivatives with increased binding affinity and specificity for monomeric Aβ(1-42) to further enhance the Aβ oligomer elimination efficacy. Out of more than 1000 D3 derivatives, we selected seven novel d-peptides, named ANK1 to ANK7, and characterized them in more detail in vitro. All ANK peptides bound to monomeric Aβ(1-42), eliminated Aβ(1-42) oligomers, inhibited Aβ(1-42) fibril formation, and reduced Aβ(1-42)-induced cytotoxicity more efficiently than D3. Additionally, ANK6 completely inhibited the prion-like propagation of preformed Aβ(1-42) seeds and showed a nonsignificant tendency for improving memory performance of tg-APPSwDI mice after i.p. application for 4 weeks. This supports the hypothesis that stabilization of Aβ monomers and thereby induced elimination of Aβ oligomers is a suitable therapeutic strategy.

Structural Insights into Curli CsgA Cross-β Fibril Architecture Inspired Repurposing of Anti-amyloid Compounds as Anti-biofilm Agents

“…We next sought to investigate whether known inhibitors of human pathological amyloid formation would effectively inhibit CsgA fibrillation on the basis of this proposed structural similarity. We tested a group of synthetic D-enantiomeric peptides (referred to here as D-peptides) designed against Aβ (55)(56)(57)(58)(59)(60)(61)(62)(63)(64)(65). Two of the D-peptides tested, ANK6 and DB3DB3 (60), were found to inhibit CsgA fibrillation in dose-dependent manners.…”

“…The structural similarity between fibrillar spine segments derived from CsgA and those derived from human pathological amyloids prompted us to investigate whether fibrillation inhibitors designed against human amyloids could also inhibit curli formation. Accordingly, we found that two D-enantiomeric peptides, originally designed to interfere with the formation of oligomers of Alzheimer's disease-associated Aβ (55)(56)(57)(58)(59)(60)(61)(62)(63)(64)(65), inhibited the fibrillation of CsgA spines as well as of full-length CsgA and reduced biofilm formation in curli-expressing Salmonella typhimurium in dosedependent manners. These results provide structural insights into a biofilm-related amyloid and pave the way for the rational development of anti-microbial drugs targeting amyloid-structured biofilms.…”

Pre-Clinical Safety and Efficacy Evaluation of Amytrap, a Novel Therapeutic to Treat Alzheimer’s Disease

“…Initially our research led to the development of a prototype RI-peptide (with seq from 16-23 of A␤ peptide) which was utilized to obtain proof of concept data in vitro followed by in vivo studies in APPSWE/Tg2576 mice [16]. The present work is an extension of this earlier work with the identification [32]. RI-peptides have been shown to be very selective for their target and are thus less likely to cross-react with other proteins [33].…”

Monomeric states of the beta-amyloid peptide investigated under high pressure by nuclear magnetic resonance spectroscopy

“…74 Many studies with analogs of D3 have been performed lately. 72,[75][76][77][78][79][80] It was shown that RD2 has a strong binding to Aβ. 75 In tandem versions of D3 (D3D3) and RD2 (RD2RD2 and RD2D3) were tested in mice bearing the Swedish and London APP mutations.…”

“…80,81 New variants were designed from D3, showing improved properties (it is worth mentioning DB3, rpitrlrthqnr * and ANK6, rkrirlvtkkkr * ). 77,78 Figure 1.8 -D3, RD2 and RD2D3 D-enantiomeric peptides. D3 and RD2 have the exact 12 amino acid residues content and a molecular weight of 1.6 kDa.…”