Production of anti-amyloid ß antibodies in mice fed rice expressing amyloid ß.

The main signs of Alzheimer's disease (AD) are cognitive impairment and senile plaques composed of amyloid beta (Aß) observed in patients' brains. Therefore, therapy for AD focuses on the removal of Aß. We developed an "edible vaccine" that employs intestinal immunity with little to no side effects. Rice was utilized as an edible vaccine. It expressed GFP-Aß42. Aß rice was administered orally to wild-type (WT) mice causing production of anti-Aß antibodies. Since Aß rice was mixed with the cholera toxin B subunit (CTB), antibody against the rice seed protein was also produced. Then, mice were caused to develop immune tolerance against the rice seed protein by oral administration of Aß rice mixed with CTB. The results indicated that only anti-Aß antibodies were produced.

Reduction of amyloid beta-peptide accumulation in Tg2576 transgenic mice by oral vaccination.

Alzheimer's disease (AD) is pathologically characterized by the presence of extracellular senile plaques and intracellular neurofibrillary tangles. Amyloid beta-peptide (Abeta) is the main component of senile plaques, and the pathological load of Abeta in the brain has been shown to be a marker of the severity of AD. Abeta is produced from the amyloid precursor protein by membrane proteases and is known to aggregate. Recently, immune-mediated cerebral clearance of Abeta has been studied extensively as potential therapeutic strategy. In previous studies that used a purified Abeta challenge in a mouse model of AD, symptomatic improvement was reported. However, a clinical Alzheimer's vaccine trial in the United States was stopped because of severe side effects. Immunization with the strong adjuvant used in these trials might have activated an inflammatory Th1 response. In this study, to establish a novel, safer, lower-cost therapy for AD, we tested an oral vaccination in a wild-type and a transgenic mouse model of AD administered via green pepper leaves expressing GFP-Abeta. Anti-Abeta antibodies were effectively induced after oral immunization. We examined the immunological effects in detail and identified no inflammatory reactions. Furthermore, we demonstrated a reduction of Abeta in the immunized AD-model mice. These results suggest this edible vehicle for Abeta vaccination has a potential clinical application in the treatment of AD.