Journal of Clinical and Experimental Ophthalmology
Open Access

Abstract

Thiol and Glutathione Homeostasis Parameters as Plasma Biomarkers of Oxidative Stress in Age-Related Macular Degeneration

Serdar Bilici*, Mehmed Ugur Isik and Murat Alisik

Purpose: To determine extracellular thiol homeostasis and intracellular glutathione homeostasis as a plasma biomarker for oxidative stress and to compare these parameters in non-exudative/exudative AMD patients and healthy individuals.

Method: 30 non-exudative AMD, 28 exudative AMD, and 36 age-matched healthy control subjects enrolled to the study. Extracellular total thiol, native thiol, disulphide amounts and intracellular oxidized/reduced glutathione levels of subjects were determined, and disulphide/thiol and oxidized/reduced glutathione percent ratios were calculated.

Results: In comparison with the control group both non-exudative and exudative AMD patients had higher plasma disulfide levels (20.5(4.8) vs. 4(3.1), p<0.001 and 22.5(7.5) vs. 15.4(3.1), p<0.001; respectively) and higher disulphide/thiol (6.64(2.57) vs. 5.4(1.9), p=0,002 and 7.05(3.14) vs. 5.4(1.9), p<0.001; respectively), in addition to higher oxidized glutathione levels (64.6(40.8) vs. 27.3(21.9), p=0.015 and 73.9(44.1) vs. 27.3(21.9), p=0.002; respectively) and oxidized/reduced glutathione ratio(6.48(8.35) vs. 3.14(3.31), p=0,034 and 10.21(10.28) vs. 3.14(3.31), p=0,003; respectively). Although there was no significant difference between groups in term of total thiol (361.5(61.6), 355.1(87.7) and 340.9(72.4), respectively, p=0,585); native thiol (318.8(62.4), 307.1(73.7) and 299.3(79.2), respectively, p=0,382); total reduced glutathione (986.3(282.1), 871.5(271.6) and 881.8(290.9), respectively, p=0.344) and native reduced glutathione (873.4(367.6), 723.7(379.0) and 797.2(307.5), respectively, p=0,113). However, there was no significant difference between non-exudative and exudative AMD groups in terms of both extracellular thiol homeostasis and intracellular glutathione homeostasis.

Conclusion: Greater extent of both extracellular disulphide and intracellular oxidized glutathione production occurred in AMD patients compared to age-matched healthy controls indicates the role of increased oxidative stress in AMD development. Further studies are needed to confirm the pathophysiologic role of homeostasis in these buffer systems in AMD.

Published Date: 2020-11-06; Received Date: 2020-10-16