01.05.2012

Researchers make "major AMD breakthrough"

Researchers make "major AMD breakthrough"

By Adrian Galbreth

As the leading cause of sight loss in the western world, experts are understandably keen to make a breakthrough in the treatment of age-related macular degeneration (AMD), and specialists in the US appear to have done exactly that.

Led by Dr Jayakrishna Ambati, University of Kentucky researchers have made a major discovery in the "dry" form of age-related macular degeneration, which is also known as geographic atrophy (GA).

It is an untreatable condition that causes blindness in millions of individuals due to the death of retinal pigmented epithelial cells, but means of combating this is detailed in their new study.

Entitled DICER1 loss and Alu RNA Induce Age-Related Macular Degeneration via the NLRP3 Inflammasome and MyD88, and published in the journal Cell, the new research is based on previous studies showing that there is a deficiency of the enzyme DICER1 in human eyes with geographic atrophy, which leads to accumulation of toxic Alu RNA molecules in the retinal pigmented epithelium.

The new study that when these RNAs build up in the eye, they trigger activation of an immune complex known as the NLRP3 inflammasome, which in turn leads to the production of a molecule known as IL-18, which causes death of retinal pigmented epithelial cells and vision loss by activating a critical protein known as MyD88.

The experts found that activity of the inflammasome, IL-18, and MyD88 were all increased in human eyes with GA.

Specialists also showed that blocking any of these components could prevent retinal degeneration in multiple disease models.

Dr Ambati, professor of physiology and professor and vice chair of ophthalmology and visual sciences at the University of Kentucky said he is "excited" that blocking these pathways could herald a new potential therapy for GA, for which there is currently no approved treatment for use by sufferers.

by Emily Tait


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