Novel Peptain for Neuroprotection in Glaucoma

Purpose: To determine if intravitreal administration of the core peptide of [alpha]-B crystallin, peptain-1 (P1) conjugated to a cell permeable peptide (CPP) (named P1-CPP) could inhibit retinal ganglion cell (RGC) death and functional decline in a rodent model of glaucoma. Methods: Primary RGCs were treated with endothelin-3 (ET-3) in the presence of either P1-CPP (12.5 µg/ml) or vehicle, following which RGC survival was assessed. In a different set of experiments, intraocular pressure (IOP) was elevated in one eye of Brown Norway (BN) rats and intravitreally injected with 2 µl of either P1-CPP or vehicle, once in a week for 6 weeks. RGC function was assessed by the pattern electroretinogram (PERG) amplitude. Retinal flat mounts were imaged and surviving RGCs were counted. Results: ET-3 treatment lead to 24% of RGCs loss compared to vehicle treated cells (p< 0.0001). P1-CPP treatment significantly lowered the ET-3-mediated cell loss (7% cell death, p< 0.001). IOP elevation in vehicle injected animals produced 11% and 27% loss of RGCs, in central and peripheral retina respectively, which was significantly lower in P1-CPP treated rats (7% loss in both eccentricities, **p< 0.01). P1-CPP treatment also promoted axonal protection during IOP elevation. IOP elevation caused 63% decline in the PERG amplitude (*p< 0.03) in comparison with naïve rats, which was sustained by P1-CPP treatment. Conclusion:The intravitreally injected P1-CPP provides cellular as well as functional protection of RGCs, which could facilitate neuroprotection against glaucomatous insults.