Cholesterol-Lowering Drugs can Help Treat Eye Disease

Cholesterol-lowering drugs may be used to treat macular degeneration - a disease of the eye that leads to blindness, a new study shows.

Researchers from Washington University School of Medicine in St. Louis reported that they found a link between arteriolosclerosis and age-related macular degeneration. Risks for both the conditions increase when the body is unable to remove fat.

The study focused on key immune system cells called macrophages. As the levels of cholesterol increase, these macrophages begin to malfunction.

"Based on our findings, we need to investigate whether vision loss caused by macular degeneration could be prevented with cholesterol-lowering eye drops or other medications that might prevent the buildup of lipids beneath the retina," says Rajendra S. Apte, M.D., PhD, and senior author of the study.

AMD is detected by the presence of 'drusen', which are recognized during an eye exam as yellowish deposits in the macula. Macula is the central region of the retina; a delicate membrane that acts like a screen reflects the light in the eye. AMD can either be "dry" or "wet", depending upon the formation of blood vessels, according to National Eye Institute.

In the "dry" type of the diseases, doctors can see fat deposits beneath the retina that damage the central part of the vision.

In the "wet" type, the aging macrophages start accumulating cholesterol and create an inflammatory process that leads to a buildup of small blood vessels in the eye.

"Ultimately, that inflammation creates a toxic mix of things that leads to new blood vessel growth," Apte said in a news release. "Most of the vision loss from 'wet' macular degeneration is the result of bleeding and scar-tissue formation related to abnormal vessel growth."

The present study was conducted on old mice. Researchers found that as mice aged, their macrophages started lacking a key protein called ABCA1 that clears protein from the cell. This inability to remove the excess fat meant that the cells couldn't stop the blood vessels from being formed in the eye, which led to the severe "wet" form of the disease.

Researchers then tested whether restoring the key protein could help the macrophages remove cholesterol.

"We were able to deliver the drug, called an LXR agonist, in eye drops. And 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," said Abdoulaye Sene, PhD, a postdoctoral fellow in the Apte lab and first author of the study.

The study is published in the journal Cell Metabolism.                       

The U.S. has about 1.8 million adults 40 years or older that are affected by AMD, and an additional 7.3 million with large drusen are at risk of developing AMD, says National Eye institute. By 2020, the country will have about 2.90 million people with AMD.