ABSTRACT
Brain accumulation of soluble oligomers of the amyloid-ß peptide (AßOs) is increasingly considered a key early event in the pathogenesis of Alzheimer's disease (AD). A variety of AßO species have been identified, both in vitro and in vivo, ranging from dimers to 24mers and higher order oligomers. However, there is no consensus in the literature regarding which AßO species are most germane to AD pathogenesis. Antibodies capable of specifically recognizing defined subpopulations of AßOs would be a valuable asset in the identification, isolation, and characterization of AD-relevant AßO species. Here, we report the characterization of a human single chain antibody fragment (scFv) denoted NUsc1, one of a number of scFvs we have identified that stringently distinguish AßOs from both monomeric and fibrillar Aß. NUsc1 readily detected AßOs previously bound to dendrites in cultured hippocampal neurons. In addition, NUsc1 blocked AßO binding and reduced AßO-induced neuronal oxidative stress and tau hyperphosphorylation in cultured neurons. NUsc1 further distinguished brain extracts from AD-transgenic mice from wild type (WT) mice, and detected endogenous AßOs in fixed AD brain tissue and AD brain extracts. Biochemical analyses indicated that NUsc1 targets a subpopulation of AßOs with apparent molecular mass greater than 50 kDa. Results indicate that NUsc1 targets a particular AßO species relevant to AD pathogenesis, and suggest that NUsc1 may constitute an effective tool for AD diagnostics and therapeutics.
