Abstract
Abstract: :
Purpose: Thioredoxin (TRX) is a 13kDa protein with antioxidant effect and has been shown to be induced in a variety of diseases with oxidative–stress. In this study, we elucidated whether TRX exist in normal human tears, and whether or not it is induced in the diseased situations on ocular surface. Methods: Tear samples were collected from 73 eyes of 64 subjects. Forty eyes of 36 subjects have been diagnosed with various diseases affecting cornea and/or conjunctiva. Thirty three eyes of 28 subjects, with no past history of ocular disease, were used to detect the levels of TRX in normal human tears. The concentrations of TRX in tears were examined using an enzyme linked immunosorbent assay (ELISA) procedure. In addition, western blotting was performed to confirm TRX existence in tears. Immunohistochemical analysis was used to elucidate the source of TRX protein. Results: TRX was detected in normal human tears at concentrations of 164.3 ± 104.8 ng/ml (mean ± SD) in basal tears (N=22) and 80.8 ± 51.4 ng/ml in reflex tears (N=11). Extremely high levels of TRX (5943.1 ± 2520.8 ng/ml) were detected in the eyes with persistent inflammation after chemical or thermal injury (N=3). In the eyes with chronic inflammation (Stevens–Johnson syndrome, ocular pemphigoid, ect), large amounts of TRX, 2816.2 ± 1923.1 ng/ml, were also detected (N=18). In the eyes with acute inflammation (chemical or thermal injury, fungal keratitis, Mooren’s ulcer, etc), moderately high levels of TRX were detected (715.2 ± 371.9 ng/ml, N=12). There existed low levels of TRX in non–inflammatory eyes (171.9 ± 121.3 ng/ml, N=7). The results of western blotting were compatible with those of ELISA. TRX protein was detected in the epithelial layer of normal cornea and conjunctiva, and high expression of TRX was detected in the epithelium with persistent inflammation or chronic inflammation. Conclusions: These findings suggest that ocular surface epithelium produce TRX in normal status and inflammatory situations. Induced TRX in acute, persistent or chronic inflammation may play a role to reduce oxidative stress.
Keywords: oxidation/oxidative or free radical damage • inflammation • cornea: epithelium