Neuropeptide could have role in retinal trauma

Fort Lauderdale, FL-In studies that could have bearing on the treatment of soldiers and others who experience trauma to the retina or central nervous system, Joan Stein-Streilein, PhD, has hypothesized that the receptor antagonist of Substance P, a neuroinflammatory peptide, may have a therapeutic role.

Dr. Stein-Streilein is senior scientist and Margaret S. Sinon Scholar in Ocular and Neurological Inflammation Research at the Schepens Eye Research Institute, Massachusetts Eye and Ear Center, Boston. Using a retinal laser burn (RLB) model in mice to study what happens to immune regulation in an injured retina, Dr. Stein-Streilein found that RLB induces extended bilateral loss of anterior chamber associated immune deviation (ACAID). In one study, immune regulation was not restored in either the burned or contralateral eye 77 days after trauma.

To determine why the contralateral eye lost the immune privilege, she conducted further studies to see if injuries more distant in the central nervous system also mitigated regulation in the eye. As in the earlier studies, both eyes were affected and had not regained immune regulation by 21 days. Similar results were found in studies of traumatic brain injury.

As they investigated the reason for the loss of immune privilege, Dr. Stein-Streilein and colleagues suspected that Substance P was involved in a change of neuronal signals and looked for evidence in its receptor, NKR-1. After corroborating this idea, the team tested a receptor antagonist, Spantide I, and found that it restored the ability to induce ACAID, but only very early after it was injected into the anterior chamber.

These studies seem to confirm that Substance P plays a role in optic nerve crush and exaggerates the immune response, allowing inflammation post-injury, Dr. Stein-Streilein said. The early findings suggest that it is also possible that a Substance P receptor antagonist could be used as part of novel therapy for ocular or central nervous system trauma.

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