Age-related macular degeneration (AMD) and diabetic retinopathy are eye diseases which cause the death of nerves in the retina, the part of the eye which senses light. When the nerves in the retina die, they can no longer sense light, which in turn leads to loss of vision. AMD is the leading cause of vision loss in the UK, affecting more than 600,000 people.

Diabetic retinopathy is the most common cause of vision loss in people suffering from diabetes, and the leading cause of visual impairment and blindness in working-age people. In both diseases there is currently no cure.

One factor that both diseases have in common is inflammation, a normal response of the body to injury. During inflammation, cells release signals which help the body to recognise the problem – after time, this signalling stops and healing begins.

In AMD and diabetic retinopathy, however, the inflammatory signals are not switched off. One particular signal, ATP, is recognised by molecules on the cell surface called P2X7 receptors, causing them to open holes, or channels, in the cell membrane. The continued presence of ATP means that P2X7 receptors stay switched on, the channels stay open and the cells die.

Dr Mark Young and his team at Cardiff University are testing their hypothesis that if they can stop the P2X7 receptors from opening channels, by blocking them, this will stop the cell death, and consequently stop the vision loss experienced by people suffering from AMD or diabetic retinopathy.

Previous research done by their team, funded by the Welsh National Research Network, has allowed them to develop a molecule called C25 that blocks P2X7 receptors. This research is very promising but still at an early stage; so they now need to modify the chemical makeup of C25 to make it better at its job of blocking P2X7, to get the best possible drug. They will also test C25 (and the improved drugs) on retinal cells to make sure that the drug blocks the receptor in a real-world setting.

If better versions of C25 can be made, and that they block P2X7 receptors on retinal cells, then further funding would allow them to test these drugs in suitable animal models of AMD and diabetic retinopathy, which is the next step in the process of drug development, and would lead to clinical trials in humans.

Read more about AMD here.

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