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K. B. Green-Church, R. Sessler, J. J. Nichols; Proteomic Analyses in Contact Lens-Related Dry Eye. Invest. Ophthalmol. Vis. Sci. 2007;48(13):5405.
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© ARVO (1962-2015); The Authors (2016-present)
Dry eye in contact lens wearers is very common, with up to 50% experiencing symptoms and 25% experiencing a clinical sign and symptom. The purpose of this work was to quantitate protein amounts, identify individual protein abundance and protein modification markers associated with contact lens-related dry eye.
Contact lens wearers were recruited to participate, and dry eye status was determined by the presence of both a clinical sign and symptom (n = 11) while normal lens wearers (n = 10) exhibited neither. Tear film samples were collected from the tear film meniscus of subjects while wearing lenses. Individual and pooled samples were subjected to several types of proteomic analyses including 1-D SDS-PAGE, analysisof post-translational modifications (PTM’s), and protein identification by chromatography and mass spectrometry. Multiplex staining was used to observe glycosylation patterns with enzymatic treatment to remove glycosylation. Proteins of interest from gels were cut, digested with trypsin, identified by nano-liquid chromatography tandem mass spectrometry (nanoLC-MS/MS) via sequence tags.
Bradford assays of total protein was a slightly lower average protein concentration in dry eye samples. SDS-PAGE analysis of the protein bands visualized with Coomassie staining suggested a number of dry eye-dependent differences in the proteome. NanoLC-MS/MS identified ß2-microglobulin, secretoglobin A2, and serum albumin as proteins that differed between dry eye and normals. Further, SDS-PAGE analysis showed a high molecular weight protein that exhibited variable individual and symptom-dependant protein mobility (shifts in molecular weight). Further analysis by mass spectrometry identified the protein as Deleted in Malignant Brain Tumors-1 (DMBT-1). There were no apparent changes in phosphorylation of the proteome, although the overall level of glycosylation suggested a dry eye-dependent increase with numerous proteins. DMBT-1 (confirmed by nanoLC-MS/MS) appeared to be heavily glycosylated, suggesting a possible reason for the observed mobility which was observed by SDS-PAGE gels. Glycoslyation levels also appeared to be important for lactoferrin and Zn-αglycoprotein in the dry eye cohort.
Several unique proteins were identified that appear to differ in contact lens-related dry eye. Some of these proteins appear to be heavily glycosylated, while there appears to be no evidence of phosphorylation.
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