Downregulation of CRYAA, SOD1, and TPI1, observed here after a short period of DEX-induced ocular hypertension, may be involved in the onset of neural damage in steroid-induced glaucoma.

Purpose: To investigate global protein expression profiles in the trabecular meshwork (TM) of normal and glucocorticoid-induced ocular hypertensive rat eyes by proteomic analysis, which has not yet been conducted to date. Materials and Methods: A rat ocular hypertension model was produced by topical application of dexamethasone (DEX) for 4 weeks. Age-matched untreated rats served as controls. Intraocular pressure (IOP) was monitored by an electronic tonometer. TM protein expression profiling and protein identification was carried out by a two-dimensional fluorescence differential gel electrophoresis (2-D DIGE) system and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry, respectively. Results: In DEX-treated rats, average IOP was elevated significantly, as compared with controls. By the DEX treatment, 14 TM protein spots were up- or downregulated consistently in 2-D DIGE analyses. Proteins exhibiting more than 2-fold statistically significant change were identified by MALDI-TOF mass spectrometry. αA-Crystallin and βA₃-crystallin were upregulated, while the C-propeptides of type I collagen were downregulated. Conclusion: Relatively short-term glucocorticoid application induced alteration in the expression of a number of proteins, including downregulation of type I collagen C-propeptides. This could reflect impaired collagen turnover in the TM of glucocorticoid-treated eyes.

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