Iron chelation abrogates excessive formation of hydroxyl radicals and lipid peroxidation products in monocytes of patients with Eales' disease: direct evidence using electron spin resonance spectroscopy.
OBJECTIVE
Eales' disease (ED) is an idiopathic retinal vasculitis condition, which affects the retina of young adult males. Retinal changes include perivasculitis, non-perfusion and neovascularization. Disruption of blood-retinal barrier (BRB) is the common feature in intra-ocular inflammatory diseases. Disruption of BRB results in vascular hyper permeability and infiltration of circulating leukocytes into the retinal parenchyma. Monocyte (MC) activation results in oxidant thrust and subsequent tissue damage. This has been reported in various intra-ocular inflammatory diseases such as uveitis and Behcet's disease. However, there are no such reports available in ED. Hence in the present study we have investigated the role of MC activation and hydroxyl radicals (OH) production and its possible involvement in promoting the development of retinal vasculitis in patients with ED.


METHODS
Twelve patients with ED and twelve healthy volunteers were recruited for the study. MC was separated from their peripheral blood. MC from patients with ED and control subjects was stimulated with phorbol-12-myristate-acetate (PMA) and OH generated was analyzed using an electron spin resonance spectrometer (ESR). Superoxide dismutase (SOD), thiobarbituric acid reactive substances (TBARS), and iron content was determined in MC to assess the oxidant thrust and antioxidant defense.


RESULTS
OH generation was elevated in MC from patients with ED, which coincided with diminished SOD activity and elevated levels of iron and TBARS, when compared with healthy control subjects. OH generation was abrogated when MC from ED were co-incubated with PMA and iron chelators such as diethylenetriaminepentacetic acid (DTPA) and desferrioxamine. Iron chelation also inhibited TBARS accumulation restored SOD activity in MC of patients with ED.


CONCLUSIONS
For the first time we have demonstrated the production of OH generation in MC of patients with ED using ESR. Further we have shown the beneficial effect of iron chelation in mitigating free radical mediated changes in cellular metabolism. Based on our findings, we provide further evidence for the role of oxidant thrust in promoting retinal tissue damage in patients with ED.
Rajesh
Mohanraj
M
Biochemistry Department, Vision Research Foundation, Sankara Nethralaya, Chennai, India.
Sulochana
Konerirajapuram N
KN
Ramakrishnan
Sivaramakrishnan
S
Biswas
Jyotirmay
J
Manoharan
Periakaruppan T
PT
D000328:Adult; D003676:Deferoxamine / Q000494:pharmacology; D004578:Electron Spin Resonance Spectroscopy; D006801:Humans; D017665:Hydroxyl Radical / Q000378:metabolism*; D007501:Iron / Q000378:metabolism; D007502:Iron Chelating Agents / Q000494:pharmacology*; D015227:Lipid Peroxidation / Q000187:drug effects*; D008297:Male; D009000:Monocytes / Q000187:drug effects* / Q000378:metabolism; D018384:Oxidative Stress; D004369:Pentetic Acid / Q000494:pharmacology; D031300:Retinal Vasculitis / Q000378:metabolism*; D013054:Spectrophotometry, Atomic; D013482:Superoxide Dismutase / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism
D007502:Iron Chelating Agents; D017392:Thiobarbituric Acid Reactive Substances; D017665:Hydroxyl Radical; D004369:Pentetic Acid; D007501:Iron; D013482:Superoxide Dismutase; D003676:Deferoxamine; D013755:Tetradecanoylphorbol Acetate