Roles of cytokines in diabetic retinopathy.

Background: Diabetic retinopathy is a progressive vision threatening complication of diabetes. Raised plasma level of tumor necrosis factor and other cytokines are accepted as the key in early events in the development of vascular disease. Objective: The aim of this study was to assess the level of some cytokines in diabetic retinopathy and its effect on the severity of diabetic retinopathy. Patients and Methods: This study was conducted on 60 diabetic patients and 15 healthy subjects as a control group. Diabetic patients were subdivided into 4 groups, group 1 included 15 cases without retinopathy, group 2 included 15 cases with non proliferative DR, group 3 included 15 cases with preproliferative DR, group 4 included 15 cases with proliferative DR. Full ophthalmological examination was done and any posterior segment pathologies was excluded. Blood samples were taken and quantitative determination of glycohemoglobin (HbA1C), ELIZA assay was used to determine the levels of different cytokines. Urine samples were collected to determine the level of ketone bodies and to test for microalbuminuria. Results: There was a significant correlation between the level of tumor necrosis factor (TNF) and the degree of retinopathy, the mean level in group 1 (40.7 ±5.3) in group 2 (98.5± 6.8), in group 3 (116.1 ±6.2), in group 4 was (313.7±71). Its level was also elevated in vitreous samples in group 3 and 4, group 3 (216± 17), group 4 (260.13. ±7). Interlukin 6 showed marked elevation in blood and vitreous in diabetic patients with advanced retinopathy, group 3 and 4, group 3 (107 ± 120) blood, vitreous (120±31), group 4 (253.7±130) blood, vitreous (200± 1.1). There was a strong correlation between ketosis and elevated TNF and interlukin 6. Conclusion: In diabetic retinopathy the increased level of some cytokines as tissue necrosis factor and interlukin 6 may stimulate endothelial cells for neovascularization process, there was a significant correlation between clinical grades of diabetic retinopathy and the expression levels of cytokines.