Vaccine shows promise in animal model.

2004 MAR 31 - (NewsRx.com & NewsRx.net) -- A new vaccine for Alzheimer disease created by researchers at the Farber Institute for Neurosciences at Thomas Jefferson University in Philadelphia has shown promise in initial testing in primates.

Vaccinating the animals with beta-amyloid, the sticky protein substance that builds up in the Alzheimer brain that is thought to play a major role in destroying nerve cells and in cognitive and behavioral problems associated with the disease, resulted in a significant increase in plaque-clearing antibodies circulating in the bloodstream.

Scientists, led by Farber Institute for Neurosciences Director Sam Gandy, MD, PhD, reported their results in the March 2004 issue of the journal Alzheimer Disease and Associated Disorders.

While a mouse model of Alzheimer is well established, researchers have run into problems in developing a human vaccine. In earlier human trials, a small group of patients developed encephalitis, or brain inflammation, from an immune response gone awry. "It would be invaluable to have a better model of Alzheimer's that is closer physically and genetically to humans," said Gandy, who is also professor of neurology, and biochemistry and molecular pharmacology at Jefferson Medical College and vice chair of the National Medical and Scientific Advisory Council of the Alzheimer's Association.

Gandy and his colleagues tested the vaccine in four aged rhesus monkeys. Two monkeys were given beta-amyloid; the other two were given a placebo. Aging nonhuman primates develop some plaque, though less than a person with Alzheimer, Gandy said.

The vaccinated monkeys developed high levels of antibodies to beta-amyloid, while the circulating amyloid levels in the vaccinated monkeys increased 5- to 10-fold, nearly all of which was bound to antibodies and cleared out. The two control monkeys vaccinated with a placebo had much lower circulating beta-amyloid levels.

"The amyloid in the brain seemed to be bound up to antibodies in the blood and cleared away," Gandy said. "We're clearly mimicking the biochemistry in the monkey that we have seen in mice. Vaccinating with amyloid brings an immune response that stimulates ...