Proteomic changes in retina after transient middle cerebral artery occlusion

Abstract

Purpose :
Retinal ischemia remains a severe debilitating condition accounting for the majority of visual impairments among patients. However, to this date the molecular mechanism involved are not fully understood. By obtaining a mapping of expressional changes in the retina after ischemia we may provide a novel insight into potential molecular mechanism and new therapeutic targets.

Methods :
The right ophthalmic artery was occluded for 2 hours prior to reperfusion in nine wistar rats, while the left served as an internal control. A silicone filament was inserted through the internal carotid artery until blood flow reduction was confirmed in the middle cerebral artery via laser-doppler. Due to the ophthalmic artery’s proximal branching, retinal ischemia was also induced. Confirmation of both brain and retinal damage was obtained by TTC and immunohistochemical analysis where gliosis marker GFAP was seen to be upregulated 48 hours after occlusion in the occluded eye compared to controls. 48 hours after occlusion the eyes were enucleated and the retinas were excised for proteomic analysis. The proteins were digested with trypsin and fractionated using a pH fractionation kit. The peptides were labeled with a tandem mass tag TMT10plex kit and analyzed with liquid chromatography mass spectrometry. Raw data files were searched against the SwissProt database using MaxQuant software. Protein filtration and statistical analysis by paired t-test were performed in Perseus.

Results :
The proteomic profile showed that 3043 proteins were detected while 144 protein alteration between the ischemic and the control retinas with 99 proteins being upregulated while 45 were downregulated (p<0.05). Changes pertaining to inflammatory mediators, apoptotic suppressors, and mitochondrial proteins were abundant with cellular pathways such as the MEK/ERK1/2 being involved.

Conclusions :
This study provides new insight to the large scale protein changes resulting from transient occlusion of the ophthalmic artery via the MCAO model.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.