Immunization of Tg-APPswe/PSEN1dE9 mice with Aβ3-10-KLH vaccine prevents synaptic deficits of Alzheimer’s disease

Novel Strategy for Alzheimer’s Disease Treatment through Oral Vaccine Therapy with Amyloid Beta

Alzheimer’s disease (AD) is a neuropathology characterized by progressive cognitive impairment and dementia. The disease is attributed to senile plaques, which are aggregates of amyloid beta (Aβ) outside nerve cells; neurofibrillary tangles, which are filamentous accumulations of phosphorylated tau in nerve cells; and loss of neurons in the brain tissue. Immunization of an AD mouse model with Aβ-eliminated pre-existing senile plaque amyloids and prevented new accumulation. Furthermore, its effect showed that cognitive function can be improved by passive immunity without side effects, such as lymphocyte infiltration in AD model mice treated with vaccine therapy, indicating the possibility of vaccine therapy for AD. Further, considering the possibility of side effects due to direct administration of Aβ, the practical use of the safe oral vaccine, which expressed Aβ in plants, is expected. Indeed, administration of this oral vaccine to Alzheimer’s model mice reduced Aβ accumulation in the brain. Moreover, almost no expression of inflammatory IgG was observed. Therefore, vaccination prior to Aβ accumulation or at an early stage of accumulation may prevent Aβ from causing AD.

Locomotor Hyperactivity in the Early-Stage Alzheimer’s Disease-like Pathology of APP/PS1 Mice: Associated with Impaired Polarization of Astrocyte Aquaporin 4

Non-cognitive behavioral and psychological symptoms often occur in Alzheimer's disease (AD) patients and mouse models, although the exact neuropathological mechanism remains elusive. Here, we report hyperactivity with significant inter-individual variability in 4-month-old APP/PS1 mice. Pathological analysis revealed that intraneuronal accumulation of amyloid-β (Aβ), c-Fos expression in glutamatergic neurons and activation of astrocytes were more evident in the frontal motor cortex of hyperactive APP/PS1 mice, compared to those with normal activity. Moreover, the hyperactive phenotype was associated with mislocalization of perivascular aquaporin 4 (AQP4) and glymphatic transport impairment. Deletion of the AQP4 gene increased hyperactivity, intraneuronal Aβ load and glutamatergic neuron activation, but did not influence working memory or anxiety-like behaviors of 4-month-old APP/PS1 mice. Together, these results demonstrate that AQP4 mislocalization or deficiency leads to increased intraneuronal Aβ load and neuronal hyperactivity in the motor cortex, which in turn causes locomotor over-activity during the early pathophysiology of APP/PS1 mice. Therefore, improving AQP4 mediated glymphatic clearance may offer a new strategy for early intervention of hyperactivity in the prodromal phase of AD.

Immunization with Aβ3-10-KLH vaccine improves cognitive function and ameliorates mitochondrial dysfunction and reduces Alzheimer's disease-like pathology in Tg-APPswe/PSEN1dE9 mice

Alzheimer's disease is a common cause of dementia, for which no disease-modifying therapy is yet available. Aβ3-10-KLH, a vaccine for active immunization, has been shown to prevent pathological changes in young transgenic models of AD, but the effects of treatment with it and its effects on mitochondrial dysfunction remain unclear. We immunized 6-month-old Tg-APPswe/PSEN1dE9 mice with Aβ3-10-KLH to analyze whether it is capable of eliminating amyloid-β after its appearance. The vaccine effectively decreased amyloid-β deposits, improved cognitive function and ameliorated mitochondrial dysfunction. These results indicate the potential of Aβ3-10-KLH as a vaccine to treat AD.

Multiple Antigenic Peptide System Coupled with Amyloid Beta Protein Epitopes As An Immunization Approach to Treat Alzheimer's Disease

Latest studies suggest that Alzheimer's disease (AD) is one of the "four big killers" that threaten the health of the elderly. AD affects about 46 million people across the world, and there is a critical need for research on new therapies for treating AD. The purpose of the present study was to develop and evaluate immunogens to elicit antibodies against the formation of amyloid beta protein (Aβ), a pathological hallmark of AD, as a therapeutic strategy in AD. In this study, serial potential immunogenic epitopes were screened according to the Aβ sequence. The screened linear epitopes on the Aβ C-terminal fragment were coupled with either the carrier protein keyhole limpet hemocyanin (KLH) or the synthesized 4-branch peptide (MAP₄). MAP₄ immunogens could effectively elicit immunogenicity against Aβ_1-42 monomer and fiber in Balb/C mice. Furthermore, MAP₄ sera could also effectively inhibit the formation of the Aβ_1-42 fiber. Interestingly, one of the MAP₄ sera was able to depolymerize the Aβ_1-42 fibers that had aggregated. The monoclonal antibody, 1H7, was shown to inhibit the formation of Aβ_1-42 fiber. MAP₄ carrier may provide benefits over current immunization strategies, as it does not induce inflammation. In conclusion, the MAP₄-Aβ conjugates offer a promising approach for the development of a safe and effective AD vaccine.