Cholesterol drugs may be effective in preventing macular degeneration, a leading cause of blindness, a new study has shown.
Working in mice and human cells, researchers at the Washington University School of Medicine in St Louis found that macular degeneration shares a common link with atherosclerosis, a condition in which an artery wall thickens as a result of the buildup of fat and cholesterol.
The study, published in the journal Cell Metabolism, showed that as mice and humans age, they produce inadequate levels of the ABCA1 protein that key immune cells, macrophages, need to clear fats and cholesterol.
Macular degeneration starts in a ‘dry’ form in which lipid deposits beneath the retina become larger and slowly destroy the central part of the eye, but can progress into the ‘wet’ version, when the formation of new blood vessels can rapidly cause blindness.
Senior investigator Dr Rajendra S Apte explained; "Most of the vision loss from ‘wet’ macular degeneration is the result of bleeding and scar-tissue formation related to abnormal vessel growth."
When the scientists treated the macrophages with an LXR agonist, a drug used to treat atherosclerosis and diabetes, the cells could remove cholesterol more effectively, and the development of new blood vessels slowed down.
"We found that we could reverse the macular degeneration in the eye of an old mouse. That’s exciting because if we could use eye drops to deliver drugs that fight macular degeneration, we could focus therapy only on the eyes, and we likely could limit the side effects of drugs taken orally," added Apte.
First author Dr Abdoulaye Sene and Apte also say that since macrophages are important in atherosclerosis and in the formation of new blood vessels around certain types of cancerous tumors, the same pathway also might provide a target for more effective therapies for those diseases.
"We have shown that we can reverse the disease cascade in mice by improving macrophage function, either with eye drops or with systemic treatments," Apte said.
"Some of the therapies already being used to treat atherosclerosis target this same pathway, so we may be able to modify drugs that already are available and use them to deliver treatment to the eye."
The study was funded by the National Eye Institute, the National Heart, Lung and Blood Institute and the National Institute of Diabetes and Digestive Kidney Diseases.
Image: Macular degeneration starts in a ‘dry’ form in which lipid deposits slowly destroy the central part of the eye, but can progress into the ‘wet’ version, when the formation of new blood vessels causes blindness. Photo: Courtesy of FreeDigitalPhotos.net.