Findings: Drs. Peter Humphries and Matthew Campbell, at Trinity College Dublin in Ireland, discovered that increasing the amount of an inflammation protein in the eyes of mice engineered to have age-related macular degeneration (AMD) may prevent the progression from early “dry” to more advanced “wet” stages of the disease. The immune system is essential to protect people from harm by foreign invaders, like bacteria and viruses, but in some cases, inflammation can go out of control and cause disease. In dry AMD, waste products that build up in the retina can trigger an immune response by a collection of proteins called an “inflammasome,” leading to abnormal growth of blood vessels and wet AMD. These scientists discovered that one of the inflammasome proteins, called IL-18, actually can protect the retina. Therefore, they surmise, increasing the amount of IL-18 in the retina might prevent progression to more advanced stages of this vision-robbing disease.
Significance: Currently, there are no treatments for dry AMD. Too much inflammation in the eye can lead to wet AMD, but Drs. Humphries, Campbell, and colleagues have shown that too little inflammation may not be good either. IL-18 seems to be needed to prevent damaging blood vessels from growing into the eye. Therefore, future therapies that increase the amount of protective IL-18 in the retina could prevent the progression from dry to wet AMD.