Immune system discovery provides hope of cure for blinding disease glaucoma
Glaucoma may be an autoimmune disease that could be cured, scientists believe.
It has been thought to occur when fluid builds up in the eye, crushing the optic nerve and damaging the retina. But scientists think the blinding condition, which affects millions around the world, may actually be the result of the body's own immune system attacking cells in the eye which it mistakes for a bacterial infection.
Usually immune cells are prevented from entering the eye to prevent inflammation, but in studies in mice, researchers proved some were able to get to and eat away retinal cells.
When they looked for the same damaging immune cells in humans, scientists from the eye and ear hospital at Massachusetts Institute of Technology in Boston found people with glaucoma had five times the number compared with people with full vision.
"Our work shows there is hope for finding a cure for glaucoma, or even preventing it entirely," said Dr Dong Feng Chen, an associate professor of ophthalmology at Harvard Medical School.
"Current glaucoma therapies are designed solely to lower eye pressure. However, we've known that, even when patients with glaucoma are treated and their eye pressure returns to normal, they can still go on to have vision loss. Now we know that stress from high eye pressure can initiate an immune response that triggers immune cells to attack neurons in the eye."
Glaucoma is the leading cause of incurable blindness in Britain, affecting one in 50 people aged over 40. In the past, the condition was associated with elevated pressure in the eye. Most treatments focus on lowering pressure but, in many cases, the disease worsens.
"That led us to the thought that this pressure change must be triggering something progressive, and the first thing that came to mind is that it has to be an immune response," added Dr Chen.
Not only did they find unusual immune cells in the eyes of mice with glaucoma, but they discovered that when those cells were removed, mice did not get the condition even if they had elevated pressure in their eyes.
Further studies showed that the immune system attacked the eye cells because of proteins that help regenerate cells are similar to proteins produced by bacteria, which could lead the body to think it is battling an infection. When the team tried to induce glaucoma in mice that had never been exposed to bacteria, the animals did not develop the condition.
The team is now looking to see if there are links to other neurodegenerative disorders, such as Alzheimer's, Parkinson's and Huntington's disease.
The research was published in the journal 'Nature Communications'. (© Daily Telegraph, London)