Retinal proteomic changes following unilateral optic nerve transection and early experimental glaucoma in non-human...

In this work we compared proteomic changes in non-human primate (NHP) retinas at the onset of early experimental glaucoma (EEG) and 3 weeks after optic nerve transection (ONT), as a means to identify regulators in the retina's response to EEG and ONT. Both eyes of 7 NHPs with either unilateral EEG (n = 4) or ONT (n = 3) were enucleated. Proteins were analyzed by a label-free quantitative mass spectrometry system and the abundance of identified retinal proteins was compared between the treated eye and its contralateral control for each NHP. Cellular processes associated with regulated proteins were identified using the MetaCore program. As a result, a total of 209 and 200 proteins were identified in EEG and ONT retinas, respectively. The EEG eyes exhibited two distinguishable levels of maximum IOP: the highest IOP <27 mmHg (n = 2) and >45 mmHg (n = 2), termed mild IOP EEG and high IOP EEG eyes, respectively. A limited overlap of proteins regulated in the same direction was seen between the high IOP EEG and either the mild IOP EEG eyes or ONT eyes. Most of the proteins that were up regulated in the high IOP EEG eyes were down regulated in the mild IOP EEG eyes; the latter showed an overall down regulation that was not seen in the other two conditions. An association with cytoskeleton regulation was recognized for up-regulated proteins in the high IOP EEG eyes. We conclude that mild IOP EEG, high IOP EEG and ONT retinas exhibited condition-specific proteomic changes with little overlap between conditions. Cytoarchitecture regulation appears to be a component of the early retinal response to chronic experimental IOP elevation.