17.01.2018

UVA Doctors Discover Enzyme In Dry AMD Patients' Eyes

A new study out of the University of Virginia shows that an enzyme typically associated with infections appears in the eyes of age-related macular degeneration (AMD) patients. Eye doctors are hopeful this finding will help develop new drug therapies for people with this serious disease.

The specific enzyme researchers discovered in AMD patients' eyes is known as cGAS. This enzyme is typically activated once the body's immune system detects an infection.

Doctors say the cGAS enzyme appears in the early stages of dry AMD's development. There's no evidence in this study whether the cGAS enzyme also appears in the eyes of wet AMD patients.

Jayakrishna Ambati, a UVA professor who was the lead author on this study, said it appears the cGAS cell turns on the body's "alarm system" which begins the process of destroying retinal cells. He said he was shocked to discover the cGAS enzyme since AMD isn’t associated with viral or bacterial infections.

The discovery of cGAS in the eyes suggests this enzyme may have other duties besides activating the immune system to respond to infections. With this new data, a few researchers believe cGAS may play a key role in signaling other major diseases such as lupus, diabetes, and even obesity.

Dr. Ambati and colleagues hope their research will encourage chemists to develop a cGAS-inhibiting drug. By inhibiting cGAS's alarm response right off the bat, doctors believe this drug could significantly improve the quality of dry AMD treatment.

It will take at least a few years before such a cGAS-inhibiting drug is developed and ready for public release. However, Dr. Ambati notes that there are already many enzyme-blocking drugs on the market today, so developing a cGAS-inhibiting drug therapy shouldn't be that difficult for pharmaceutical companies.

Besides developing a drug therapy, study authors suggest ophthalmologists look into scanning patients for elevated cGAS levels at eye exams. Keeping track of cGAS levels could help eye doctors track a patient's likelihood of developing dry AMD throughout their lives.

Dry AMD, which is caused by the deterioration of retina, is the more common form of the eye disorder. Although affecting only one in ten AMD patients, wet AMD is far more serious because it is caused by leakage of retinal blood vessels.

There's no cure for either kind of AMD as of today, but there are ways doctors can slow the disease's progression. A few therapies for dry AMD patients include vitamin supplementation and laser surgery. Most wet AMD patients have to get monthly eye injections or take blood vessel growth inhibitors.

While a few AMD patients experience blurry vision early on, the disease often progresses without apparent visual symptoms. Eye doctors recommend anyone over the age of 45 to schedule at least one eye exam per year to check for AMD

AMD is one of the most common causes of blindness in people over the age of 45. Today, approximately 200 million people on earth have some form of AMD.

This study was published in a recent edition of Nature Medicine. The title of this article is, "cGAS drives noncanonical-inflammasome activation in age-related macular degeneration."


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