Active Immunotherapy with 12-mer Aβ1-42-like Assembly Vaccine Shows Efficacy in Aged 3×Tg-AD Mice

Background: Alzheimer's disease (AD) is the most common progressive neurodegenerative disorder characterized by senile plaques and neurofibrillary tangles (NFTs). The amyloid-oligomer hypothesis indicates that the buildup of toxic oligomers in vivo is likely to impair memory and synaptic function. Methods: In our study, a kind of novel recombinant chimeric 12x(Aβ1-15-Th) antigen was developed as 12-mer Aβ1-42-like assembly vaccine. We designed this 12x(Aβ1-15- Th) antigen to mimic the assembly states of Aβ1-42 using twelvefold Aβ1–15 (B cell epitopes of human Aβ1-42) and foreign human T helper (Th) epitopes (as the T cell epitopes of Aβ1-42) constructs. Its immunogenicity as a subunit vaccine was tested on C57/BL6 mice, and the efficacy was shown by applying it to AD mice. Results: This 12x(Aβ1-15-Th) vaccine induced robust Aβ-specific antibodies in 3xTg- AD and C57/BL6 mice. As early immunotherapeutic agent of AD, the 12x(Aβ1-15-Th) vaccine significantly improved the behavior performance of aged 3 x Tg-AD mice, and reduced the levels of soluble Aβ oligomers and soluble Aβ in the brain. In aged 3 x Tg- AD mice, immunotherapy with the 12x(Aβ1-15-Th) vaccine could prevent Aβ-induced decrease of synaptic proteins, which suggested that it had neuroprotective effects on the brain. Conclusion: The novel recombinant 12x(Aβ1-15-Th) chimeric vaccine targeting of pathological conformations of Aβ oligomers has shown obvious neuroprotective benefits in the preclinical AD model mouse, which indicates that it is a good candidate vaccine for the prophylaxis of AD.