For unknown reasons a protein called amyloid beta aggregates into toxic plaques in the brain, killing neurons.
These plaques are one of the hallmarks of Alzheimer's disease. Now two new animal studies show for the first time that the deadly transformation of amyloid beta into plaques can be prevented through an interaction between amyloid beta and another protein called cystatin C.
Although much work needs to be done, these new findings may open the door to new treatments for Alzheimer's disease that mimic the effects of cystatin C, says Efrat Levy, Ph.D., Associate Professor in the Departments of Psychiatry and Pharmacology at New York University School of Medicine, and the lead author of the study. “We are really excited by these findings because recent studies show that cystatin C is protective against a variety of insults that cause cell death in the brain. Our potential therapeutic approach focuses on keeping amyloid beta in a water soluble form, preventing its accumulation in the brain, and thus slowing, halting, or reversing disease progression,” says Dr. Levy, who is also Director of the Laboratory of Molecular Pathology of Cerebral Amyloidosis at the Nathan S. Kline Institute for Psychiatric Research in Orangeburg, New York.
With support from the Alzheimer's Association, Dr. Levy's laboratory has already begun studies to develop a drug that will mimic the ability of cystatin C to bind to a non-pathological form of amyloid beta and thereby prevent its accumulation into plaques in the brain.
Alzheimer's is estimated to affect 5 million Americans and there are no medicines that can delay or prevent the disease. Many laboratories worldwide are pursuing ways to prevent the clumping of amyloid beta as possible therapies for the disease. It isn't known whether the protein actually causes Alzheimer's, but amyloid beta is one of the proteins implicated in the disease process.
The two studies appear in the on-line November 18, 2007, edition of the journal Nature Genetics and will be published in its December 2007 issue.
The first study was performed by Dr. Levy in collaboration with other investigators at the Nathan S. Kline Institute for Psychiatric Research and New York University School of Medicine. The second study was performed by Dr. Levy and colleagues in the laboratory of Dr. Mathias Jucker at the Hertie-Institute for Clinical Brain Research in Tubingen, Germany.
Both studies used mice that were genetically engineered to produce human cystatin C as well as abundant amounts of amyloid beta plaques in their brains. The cystatin C bound to the soluble, non-pathological form of amyloid beta in these mice and inhibited the aggregation and deposition of amyloid beta plaques in the brain.