"Previous Alzheimer's vaccines were
protein-based," said Dr. Baoxi Qu, the study's lead author and
assistant professor in the Center for Biomedical Inventions and
internal medicine. "We wanted to try a DNA-based genetic vaccine
instead to see if we could enhance the immune response."
Although prior studies of amyloid protein vaccination had shown some
slowing in the plaque buildup, negative side effects also occurred in a
handful of patients. Some had autoimmune responses that caused
The key in the UT Southwestern study was finding another way to
vaccinate patients without stimulating the body's own immune cytotoxic
T cells, said Dr. Roger Rosenberg, a study author and director of the
Alzheimer's Disease Center.
"This dilemma was discussed with my colleagues, and we decided to try
vaccination with an amyloid gene, rather than the amyloid protein
vaccine," said Dr. Rosenberg.
The UT Southwestern researchers vaccinated mice with a "gene gun." The
gene gun and gene-vaccination technologies were invented by Dr. Stephen
Albert Johnston, director of the Center for Biomedical Inventions and
senior author of the latest study.
"We have been developing ways to use gene-immunization to manipulate
the immune response," Dr. Johnston said. "This study was the first step
to see if we can apply these techni
ques to create a safe and effective
Alzheimer's vaccine." Said Dr. Rosenberg: "When we vaccinated the mice
with the mouse form of the amyloid gene, they made lots of antibodies
without stimulating cytotoxic T cells. When we get to human studies, we
hope to show that humans can make human antibodies against the amyloid
Current treatments for Alzheimer's disease focus on the symptoms since
no therapies have been clinically proven to slow or prevent progression
of the disease. Amyloid protein deposits are present in the early phase
of the disease - a fact that suggests a gene vaccination would be a
step forward in slowing the progression of dementia.
From the mouse studies and in previous clinical trials of patients with
Alzheimer's disease, immunization with amyloids slowed the buildup of
plaque in the brain and appeared to slow cognitive loss.
"Although human clinical trials are still at least two years out,
theoretically, we are on the right track," he said.
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