Proteinous Microspheres Containing KLVFF Peptides Sequester Amyloid-Beta Protein and Inhibit its Aggregation

摘要

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized clinically by progressive impairment in memory and cognition. The neuropathology of AD is characterized by extraneuronal deposition of amyloid-β (AP) and neurofibrillary tangles. Aβ is a short polypeptide (40 to 43 amino acids) that at sufficiently high concentration tend to selfassemble into soluble aggregates, which in turn accumulate as amyloids [1]. The aggregates are associated with pathological changes in the surrounding brain neurons that lead to neuronal death and synaptic loss. Therefore, interfering with Aβ formation and aggregation or sequestering its accumulation in the brain are promising strategies for AD therapy. Lowe et al. have showed that compounds containing a recognition element KLVFF (residues 16-20 in A P) can bind to the homologous sequence in Aβ through hydrophobic and n-n interactions and disrupt its aggregation, thus protecting neurons from Aβ-associated toxicity. Therefore, this fragment was served as a lead compound for the development of inhibitory agents that are aimed at preventing Aβ aggregation in vivo [2]. Moreover, it was shown that dendrimeric analog of KLVFF display superior activity compared to the monomeric KLVFF [3]. The concept of multivalency to enhance the affinity and specificity of a ligand to its receptor is an important feature in biology. Here, we describe the design, preparation and characterization of novel proteinous microspheres (PM) decorated with KLVFF peptides at their surface, and demonstrate their efficacy to inhibit Aβ aggregation by sequestering it from the solution. The preparation of these microspheres is based on sonochemical approach that uses high-intensity ultrasound to make aqueous suspensions filled with water-insoluble liquids [4]. The microspheres are spherical microcapsules that are generated from intermolecular disulfide bonds between protein's cysteines. We snowed that the surface of such microspheres can be readily modified with different thiol containing substances through the exchange reaction with the disulphide groups of bovine serum albumin; and they can effectively encapsulate different substances such as drugs or contrasting agents.