Researchers at Sweden’s Lund University studied the immune response triggered by epileptic seizures and found that the condition produces inflammation in the retina. The results, obtained through experiments in rats, may represent an initial step for a novel noninvasive tool for the detection of brain inflammation through examination of the eyes.
The research paper, “Immune response in the eye following epileptic seizures,” was published in the Journal of Neuroinflammation.
The hallmarks of epilepsy include brain pathology consequences, such as faulty synaptic transmission, neuronal damage and exaggerated immune response. Seizure-induced immune responses have been primarily described in specific areas of the brain called epileptic focus, where the seizures start. But recent studies indicate that the seizures may disturb entire brain networks.
In this study, researchers studied rats to investigate whether the post-seizure immune response could extend beyond the epileptic focus within the temporal lobes and be detected in the retina, a remote brain area that has not been thoroughly investigated. The animals were subjected to electrically induced temporal epilepsy, and their eyes studied at six hours, one week, and seven weeks after the procedure.
Although no increase in immune response or cell death was detected in the animals’ eyes at six hours or one week, researchers saw an increase of microglia, a type of immune cell found in the central nervous system, in the eyes of the rats at seven weeks. This increase was accompanied by an increase of activation of these immune cells in the inner retina.
Treatment with a specific antibody led to the reduction of glial activation in both the retina and the epileptic focus in the brain, which suggests a similar immune activation pathway.
As retinal immune response is more accessible than the cerebral immune response, researchers believe that, according to these findings, it may become a potential noninvasive biomarker of brain inflammation. But additional research into the retinal behavior in epilepsy is necessary before the method can be confirmed as a clinically relevant diagnostic tool.
“These are the first evidence that epileptic seizures lead to an immune response in the retina. The finding has a potential to become a novel noninvasive tool for detecting brain inflammation through the eyes,” the researchers concluded.