Oxidative Stress and Antioxidant Activity in Orbital Fibroadipose Tissue in Graves' Ophthalmopathy

Abstract

Purpose: To investigate the oxidative stress and antioxidant activity in the orbit in Graves' ophthalmopathy (GO). Materials and Methods: Orbital fibroadipose tissue samples were obtained from 13 cases during orbital fat decompression surgery. All cases demonstrated features of moderate or severe GO according to the European Group on Graves' Orbitopathy classification. The disease activity was evaluated with the Clinical Activity Score, and the clinical features of GO were evaluated with the Ophthalmopathy Index. Orbital fibroadipose tissue samples of 8 patients without any thyroid or autoimmune disease were studied as controls. In the tissue samples, lipid hydroperoxide level was examined to determine the level of oxidative stress; glutathione level to determine antioxidant level; superoxide dismutase, glutathione reductase, and glutathione peroxidase activities to determine antioxidant activity. Results: Lipid hydroperoxide level and all three antioxidant enzyme activities were found to be significantly elevated, while glutathione level significantly diminished in tissue samples from GO cases compared to controls (p < 0.05). Glutathione levels in tissue samples of GO cases showed negative correlation with Ophthalmopathy Index (r = −0.59, p < 0.05). Conclusions: The antioxidant activity in the orbit is enhanced in GO. However, the oxidative stress appears to be severe enough to deplete the tissue antioxidants and leads to oxidative tissue damage. This study may support the possible value of antioxidant treatment in GO.

KEYWORDS:

• antioxidant activity
• antioxidant treatment
• Graves' ophthalmopathy
• oxidative stress