Determination of carbonyl group content in plasma proteins as a useful marker to assess impairment in antioxidant defense in patients with Eales' disease

Abstract

Purpose: Formation of protein carbonyl groups is considered an early biomarker for the oxidant/antioxidant barrier impairment in various inflammatory diseases. We evaluated the intensity of free radical reactions in patients with Eales' disease, an idiopathic inflammatory condition of the retina.

Methods: Twenty patients with Eales' disease in active vasculitis stage, 15 patients with Eales' disease in healed vasculitis stage and 20 healthy control subjects were recruited for the study. Plasma protein carbonyl groups,plasma glutathione (GSH) superoxide dismutase (SOD) activity and thiobarbituric acid reactive substances (TBARS) were determined in erythrocytes.

Results: Plasma protein carbonyl content was elevated by a factor of 3.5 and 1.8 respectively in active and healed vasculitis stages. The increase of carbonyl group content in active and healed stage of patients with Eales' disease correlated with diminished SOD activity and GSH content. There was also increased accumulation of TBARS in active and healed vasculitis stages of Eales' disease, and this correlated with diminished SOD activity.

Conclusion: Our results showed that protein carbonyl group content increases with severity of Eales' disease. The increase in carbonyl content correlated with diminished antioxidant status. This confirms an earlier report that free radical mediated tissue damage occurs in Eales' disease. The determination of protein carbonyl content may be used as a simple biomarker to monitor the efficacy of antioxidant supplementation in controlling retinal vasculitis in patients with Eales' disease.