In a new study, researchers have shown that the blood protein vitronectin is a promising drug target for dry age-related macular degeneration (AMD), a leading cause of vision loss in Americans 60 years of age and older.
The study also holds implications for Alzheimer’s and heart disease, which are linked to vitronectin.
The research was conducted by scientists at Sanford Burnham Prebys Medical Discovery Institute.
More than 11 million Americans have AMD; and this number is expected to double by 2050 as the U.S. population ages.
Of the two types of macular degeneration—wet and dry—the dry form is the most common, making up approximately 80 to 90% of cases.
While the progression of dry AMD can be slowed with lifestyle changes, such as taking vitamin supplements, eating healthy, and not smoking, no pharmaceutical treatment exists.
Dry AMD is caused by the progressive accumulation of drusen, pebble-like deposits at the back of the eye, which results in blurry vision and, over time, vision loss.
While scientists knew that these deposits contain cholesterol, fats (lipids), proteins such as vitronectin, and a mineralized form of calcium phosphate called hydroxyapatite—the same material that forms teeth and bone—how these deposits form was unknown.
In the study, the team used the structure of vitronectin—which was solved by Marassi last year—and various sophisticated biophysical tools to prove that the propeller top tightly clasps calcium and hydroxyapatite.
These findings suggest a mechanism by which vitronectin drives the formation of the abnormal deposits—and reveal how this process might be interrupted.
The team says this drug would hold promise as a treatment that slows the progression of dry AMD and potentially other plaque-related conditions.
Vitronectin is also a major component of the amyloid plaques linked to Alzheimer’s disease and the cholesterol-rich plaques that cause heart disease.
One author of the study is Francesca Marassi, Ph.D., the director of the Cancer, Molecules and Structures Program at Sanford Burnham Prebys.
The study is published in PNAS.
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