Monoclonal antibody with conformational specificity for a toxic conformer of amyloid β42 and its application toward the Alzheimer's disease diagnosis.

Kazuma Murakami,Takashi Suzuki,Ryotaro Ishii,Takahiko Tokuda,Takahiko Shimizu,Kazuhiro Irie,Yumi Irie,Ken-Ichi Akagi,Maki Tokuda,Naotaka Izuo,Harutsugu Tatebe,Masahiro Maeda,Yoko Monobe,Toshiaki Kume,Mizuho Hanaki

doi:10.1038/srep29038

Abstract

Amyloid β-protein (Aβ42) oligomerization is an early event in Alzheimer’s disease (AD). Current diagnostic methods using sequence-specific antibodies against less toxic fibrillar and monomeric Aβ42 run the risk of overdiagnosis. Hence, conformation-specific antibodies against neurotoxic Aβ42 oligomers have garnered much attention for developing more accurate diagnostics. Antibody 24B3, highly specific for the toxic Aβ42 conformer that has a turn at Glu22 and Asp23, recognizes a putative Aβ42 dimer, which forms stable and neurotoxic oligomers more potently than the monomer. 24B3 significantly rescues Aβ42-induced neurotoxicity, whereas sequence-specific antibodies such as 4G8 and 82E1, which recognizes the N-terminus, do not. The ratio of toxic to total Aβ42 in the cerebrospinal fluid of AD patients is significantly higher than in control subjects as measured by sandwich ELISA using antibodies 24B3 and 82E1. Thus, 24B3 may be useful for AD diagnosis and therapy.

Highlights

Pathologies as well as cerebral amyloid angiopathy (CAA) such as Italian mutation[7]
We previously reported a conformation-targeted monoclonal antibody (11A1)[13] against the toxic turn of Aβ4 2 generated by immunization with E22P-Aβ10–35, a minimum moiety for neurotoxicity including the toxic turn as a Pro-X corner (X: variable amino acid residue). 11A1 reacted with intracellular as well as extracellular Aβdepositions
To generate the antibody that recognizes the “toxic turn” at Glu[22] and Asp[23] of Aβ42, the seven monoclones previously selected using E22P-Aβ10–3513 containing the toxic turn were re-evaluated in detail based on their ability to react with various Aβ4 2 mutants with a proline replacement mainly at C-terminal region[8]

Summary

Introduction

Pathologies as well as cerebral amyloid angiopathy (CAA) such as Italian mutation[7]. Several conformation-specific antibodies such as anti-prefibrillar Aβoligomers (OC)[19], and anti-Aβ4 2-derived diffusible ligands (ADDLs) antibodies have been applied to AD diagnosis using cerebrospinal fluid (CSF). These attempts were likely successful in the limited cohort, almost all the target molecules of these antibodies could be Aβoligomers that move into the fibrillar stage (on-pathway)[20], so the possibility of false positives in the future trials using these antibodies cannot be excluded. 24B3 was applied to the diagnosis of AD using human CSF, as determined by a novel sandwich enzyme-linked immunosorbent assay (ELISA) that uses a combination of 24B3 and an anti-N-terminus-specific antibody, 82E1

Methods

Results

Conclusion