St. Louis -- Researchers at Saint Louis University School of Medicine have received nearly half a million dollars from the National Eye Institute to study a protein thought to be linked to Alzheimer's disease and its possible relationship to age-related macular degeneration, the leading cause of blindness in people over 60.
Apolipoprotein E (apoE) is a protein component that helps transport cholesterol in the blood between the liver and other tissues, says Steven Fliesler, Ph.D., professor and director of research in the department of ophthalmology at Saint Louis University School of Medicine and lead investigator. It also is present in the brain and other nervous tissues, including the retina.
There are three genetically determined forms of apoE (apoE-2, apoE-3 and apoE-4), each encoded by a specific sequence of DNA . Studies suggest that apoE-3 may play a protective role in the nervous system, assisting in the repair of nervous tissue, such as after a brain injury.
On the other hand, people who have elevated levels of the apoE-4 version of the protein are at an increased risk for developing the late onset, familial type of Alzheimer's disease.
The mystery SLU researchers are now trying to solve is why the reverse seems to be true when it comes to advanced macular degeneration.
"Paradoxically, the exact opposite trend seems to prevail," Fliesler says. "ApoE-4 seems to correlate with a reduced incidence of macular degeneration."
For the next two years, Fliesler and his team will test whether the presence of one or the other form of apoE slows down, quickens, or does essentially nothing to the rate of retinal degeneration in genetically altered mice that undergo progressive, age-dependent vision loss. Fliesler's team will selectively introduce either the human apoE-3 or apoE-4 gene into the mice and then study what effects this may have on the structure and function of their retinas.