Crossing the blood-brain-barrier with nanoligand drug carriers self-assembled from a phage display peptide

Lin-Ping Wu,Arnaldur Hall,Junan Su,Z Shadi Farhangrazi,Xiaolong Tan,S Moein Moghimi,Davoud Ahmadvand

doi:10.1038/s41467-019-12554-2

Abstract

The filamentous bacteriophage fd bind a cell target with exquisite specificity through its few copies of display peptides, whereas nanoparticles functionalized with hundreds to thousands of synthetically generated phage display peptides exhibit variable and often-weak target binding. We hypothesise that some phage peptides in a hierarchical structure rather than in monomeric form recognise and bind their target. Here we show hierarchial forms of a brain-specific phage-derived peptide (herein as NanoLigand Carriers, NLCs) target cerebral endothelial cells through transferrin receptor and the receptor for advanced glycation-end products, cross the blood-brain-barrier and reach neurons and microglial cells. Through intravenous delivery of NLC-β-secretase 1 (BACE1) siRNA complexes we show effective BACE1 down-regulation in the brain without toxicity and inflammation. Therefore, NLCs act as safe multifunctional nanocarriers, overcome efficacy and specificity limitations in active targeting with nanoparticles bearing phage display peptides or cell-penetrating peptides and expand the receptor repertoire of the display peptide.

Highlights

The filamentous bacteriophage fd bind a cell target with exquisite specificity through its few copies of display peptides, whereas nanoparticles functionalized with hundreds to thousands of synthetically generated phage display peptides exhibit variable and often-weak target binding
SDS-PAGE analysis revealed the presence of FAMCGY monomer and dimer below the critical aggregation concentration (CAC), but oligomers were present above the CAC (Fig. 1a)
Re-positioning of FAM to the C-terminal, while maintaining the C at the N-terminal [CGY-(K)-FAM] or changing the position of arginine 10 (R10) in FAM-CGY, or replacing the single tryptophan 13 (W13) from the sequence with a glycine (G) all prevented oligomerisation (Fig. 1e, f). These results further highlight the importance of sequence specificity in peptide self-assembly/oligomerisation, which may include R-mediated bidentate hydrogen bonding, histidine (H)-mediated hydrogen-π interactions, and additional π-π stacking contribution from the aromatic indole side-chain of W and imidazole in H

Summary

Introduction

The filamentous bacteriophage fd bind a cell target with exquisite specificity through its few copies of display peptides, whereas nanoparticles functionalized with hundreds to thousands of synthetically generated phage display peptides exhibit variable and often-weak target binding. Liposomes bearing the linear form of GYR show weak target engagement regardless of the peptide density on liposome surfaces[11] Numerous factors such as particle shape, possible changes to peptide structure and orientation during functionalization as well as ligand masking by plasma/ serum proteins may explain these discrepancies[3,4,11,12,13,14]. Interdomain interactions and disulfide bridges within the p3 protein can influence p3 organisation, which in turn may promote intermolecular bonding among adjacent display peptides to form a multivalent domain with high target binding avidity[15,16,17] This hypothesis might be applicable to the GYR peptide, where adjacent. Hierarchical forms of a brain-specific phage peptide overcome specificity limitations in active targeting and crossing of the BBB with conventional nanoparticles[11,18,19]

Methods

Results

Conclusion