Effect of rice-expressed amyloid β in the Tg2576 Alzheimer's disease transgenic mouse model.

One of the main hallmarks of Alzheimer's disease (AD) is senile plaques composed of amyloid β (Aβ). We developed a new edible vaccine: rice expressing GFP-Aβ42. In a previous report, we described the production of anti-Aβ antibodies in B6 mice fed Aβ rice mixed with cholera toxin B subunit (CTB). In this report, we investigated whether Aβ rice had therapeutic effects in the Tg2576 AD model mice. The anti-Aβ antibody titer was increased and levels of intracerebral Aβ (soluble and insoluble) and serum Aβ decreased. Because the value of IgG1/IgG2a in the Aβ feeding group was >1, immunization via Aβ rice may induce a non-inflammatory Th2 reaction. We also found that the Aβ vaccine improved memory, as assessed in a Y-maze test. The number of arm entries in the Y-maze test was lower in the Aβ feeding group than in the control group. These results suggest that the new edible vaccine Aβ rice may have therapeutic effects in AD.