Identification of proteins in the aqueous humor associated with cataract development using iTRAQ methodology

Proteins in the aqueous humor (AH) are important in the induction of cataract development. The identification of cataract-associated proteins assists in identifying patients and predisposed to the condition and improve treatment efficacy. Proteomics analysis has previously been used for identifying protein markers associated with eye diseases; however, few studies have examined the proteomic alterations in cataract development due to high myopia, glaucoma and diabetes. The present study, using the isobaric tagging for relative and absolute protein quantification methodology, aimed to examine cataract-associated proteins in the AH from patients with high myopia, glaucoma or diabetes, and controls. The results revealed that 445 proteins were identified in the AH groups, compared with the control groups, and 146, 264 and 130 proteins were differentially expressed in the three groups of patients, respectively. In addition, 44 of these proteins were determined to be cataract‑associated, and the alterations of five randomly selected proteins were confirmed using enzyme-linked immunosorbent assays. The biological functions of these 44 cataract-associated proteins were analyzed using Gen Ontology/pathways annotation, in addition to protein‑protein interaction network analysis. The results aimed to expand current knowledge of the pathophysiologic characteristics of cataract development and provided a panel of candidates for biomarkers of the disease, which may assist in further diagnosis and the monitoring of cataract development.