Decreased platelet membrane fluidity in retinal periphlebitis in Eales' disease

Purpose: Oxidative damage to cellular membranes plays an important role in the pathobiology of tissue injury. Free radical-induced peroxidation of membrane lipid and protein is associated with alterations in cellular, morphological, biochemical, and physical dynamics, which are related to the mobility of lipid molecules. Retinal photoreceptors and platelets have been shown to be an easy target of oxidants because of their high proportion of polyunsaturated fatty acids. This study was undertaken, for the first time, to investigate membrane fluidity in the platelets of patients with Eales' disease. Methods: Assays of malonaldialdehyde levels and the enzymes superoxide dismutase and catalase and fluorescence polarization, for estimating membrane fluidity, were carried out on platelets from 20 patients with Eales' disease ( stage 1 characterized by periphlebitis of small (1a) and large (1b) caliber vessels with superficial retinal hemorrhages) and 15 healthy controls. Results: A significant increase was observed in the malonaldialdehyde levels. A significant decrease in the activity of superoxide dismutase and catalase was also observed. Platelet fluorescence polarization was significantly higher in the patients, indicating decreased membrane fluidity compared to controls ( p < 0.01). Conclusion: A decrease in platelet membrane fluidity occurs as a result of oxidative stress in retinal periphlebitis in Eales' disease. The decreased membrane fluidity suggests alterations in the physiological events, which may result in alterations in the functioning of retinal photoreceptors.