Abstract
Purpose :
“Excitotoxicity”, defined as a toxic condition resulting from a glutamate overflow that leads neuronal cells to die, including retinal ganglion cells (RGCs). Up today, no drugs able to neuroprotect the retina from degeneration on the market.
Therefore, by using several in-vitro and in-vivo experiments we aimed at investigating whether JGRi1, able to disrupt JNK2-STX1a interaction and prevent glutamate spillover, could be a novel molecule for retinal neuroprotection.
Methods :
Multiple cultured cell lines were treated with different JGRi1dosages, and its protective effect was assessed by measuring both cell viability and cell death when challenged with NMDA.
Then, we addressed the biodistribution of JGRi1 as topical administration by a fluorescently tagged version of the peptide. The neuroprotective effect of JGRi1 on murine retina was assessed both in vivo and ex vivo by using a previously established optic nerve cut (ONC) model.
Ultimately, we tested if the eyedrops administration of JGRi1 could slow down the degeneration in a murine model of retinal excitoxicity induced by intraocular injection of NMDA.
Results :
JGRi1, successfully promoted cell viability (p<0.01) and reduced cell death (p<0.01) upon NMDA stimulation in cell lines. Interestingly, JGRi1 did not prevent extracellular calcium entry, meaning that the NMDA receptor still retains its functionality (p<0.001). As expected, NMDA stimulation led to a increase of JNK2 expression (p<0.01), as well as JNK phosphorylation, which were reduced by JGRi1 (p<0.05)
We also report that JGRi1 can reach the retina, as both ex vivo application on enucleated eyeballs and in vivo treatment of mice with fluorescently tagged version of JGRi1 led to a significant accumulation of the peptide on the retina in a dose-dependent fashion (p>0.001). JGRi1 accumulation on the retina effectively reduced RGC death and improved their survival in the ONC assay (p<0.01) and it reduced the levels of both phosphorylated JNK and STX1a (p<0.05).
Moreover, JGRi1 is able to protect RGC cells on the retina of mice upon intraocular NMDA injection.
Conclusions :
JGRi1 protects against NMDA-mediated toxicity, without affecting NMDA receptor functioning in multiple cell types. Additionally, it effectively reaches the retina in both ex vivo and in vivo treatments granting RGC neuroprotection in the used models of retinal injury.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.