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Aihua Hou, Kai Poon Law, Min Qi Tin, Yoon Pin Lim, Louis Tong; Secretomics in pterygium-derived fibroblasts: discovery of pathological molecules in disease. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):803.
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© ARVO (1962-2015); The Authors (2016-present)
Pterygium is a wing-shaped ocular surface lesion growing from conjunctiva towards central cornea, causing irritation, astigmatism and visual disturbance. It is characterized by epithelial proliferation, fibrovascular growth, chronic inflammation, and prominent extracellular matrix remodeling. Previous studies suggest that aberrant extracellular proteins secreted by dysregulated fibroblasts leads to abnormal matrix production and tissue invasion in the pathology of pterygium. The aim of this study is to identify dysregulated secreted proteins in primary pterygium fibroblasts.
Primary fibroblasts were cultured from pterygium and conjunctival tissue explants excised from the same patient. Cells were expanded in serum media, and subsequently cultured in serum-free medium for 24hrs. Culture media were collected, concentrated, and ITRAQ-based tandem mass spectrometry employed to relatively quantify proteins secreted from 3 pairs of pterygium and conjunctiva fibroblasts. The fold change and statistical significance of dysregulated proteins in pterygium fibroblasts were determined, and classical and non-classical secreted proteins were identified using bioinformatics tools.
Among each pair of samples, only proteins identified with 95% confidence are included. A total of 433 proteins common among all pairs of samples were identified. Among these proteins, 48.0% (208) possess a signal peptide, are classically secreted proteins, 17.1% (74) have been predicted to be ‘secreted’ via non-classical secretion pathways, while 31.2% (135) are exosome proteins. A minority of 3.7% are not previously known to be secreted, or represent contaminants.<br /> <br /> Only proteins found to be dysregulated in the same direction in at least 2 out of 3 pairs of samples are considered as significant. This criterion produced 31 and 27 up-regulated and down-regulated proteins in pterygium respectively. Molecular function analysis showed that these proteins are involved in catalytic activity, structural molecule activity, receptor activity and binding. Pathway analysis revealed that 14 of these proteins are involved in integrin signaling.
Assuming cultured fibroblasts recapitulate their native behavior, 58 proteins could have been secreted abnormally in pterygium disease and contribute in some way to the pathology. In addition, these molecules may serve as affect extracellular ligands for integrin signaling.
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