Proteomic Analysis of Aqueous Humor Reveals Progression of Diabetes Mellitus in the Anterior Chamber

Abstract

Purpose : To identify the complete protein profile of human aqueous humor in diabetic and non-diabetic donor eyes and determine the protein pathways and interaction networks that differentiate these groups.

Methods : Human aqueous humor samples from 6 advanced diabetic (insulin dependence with specified complications due to diabetes), 5 non-advanced diabetic (insulin or non-insulin dependent lacking complications due to diabetes), and 6 control non-diabetic eye donors were collected within 6 hours post-mortem. Samples were analyzed by ultra high pressure liquid chromatography tandem mass spectrometry (UHPLC-MS/MS). The proteins identified were analyzed further using Ingenuity Pathway Analysis to determine significant pathways present, Partek Genomics Suite to determine statistically significant protein expression differences, String database to determine networks within the lists of proteins, and Panther for gene ontology.

Results : We identified an average of 126,109 spectra with an average of 4,531 unique peptides, corresponding to an average of 1,398 unique proteins. Statistical analysis of the protein lists identified 682 proteins with differential expression changes as diabetes progresses. Several of these proteins play important roles in oxidative stress management (Glutathione-S-transferase mu 1; GSTM1), plasma protease inhibition (Serine Proteinase Inhibitor, Clade C, Member 1; SERPINC1), and regulation of inflammation (Complement Protein 4A; C4A). Major pathways identified in diabetic progression in the aqueous proteome include: glutathione-mediated detoxification, coagulation system, and compliment cascade.

Conclusions : We have identified several unique proteins, pathways, and interaction networks that suggest a breakdown in the blood aqueous barrier and corresponding increases in oxidative stress and inflammation in the anterior chamber as diabetes progresses. Protein differences identified may give insight into environmental changes that may influence the health of neighboring cells dependent on the aqueous humor for function and survival including the corneal endothelium and trabecular meshwork.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.