Inflammation and diabetic retinopathy

PURPOSE: To investigate the relationship between inflammation in the vitreous and diabetic retinopathy. METHODS: Vitreous samples from 21 patients with proliferative diabetic retinopathy (PDR), 21 patients with nonproliferative diabetic retinopathy (NPDR), and 21 nondiabetic patients with idiopathic epiretinal membranes (control) were studied. The interferon-gamma (IFN-γ), tumor necrosis factor-alpha (TNF-α), matrix metalloproteinase (MMP)-2, MMP-9, and adiponectin levels in the vitreous were detected in all samples with enzyme-linked immunosorbent assay (ELISA). Samples were stored at −80 °C until analyzed. RESULTS: The TNF-α levels in the vitreous were not statistically significant between all groups (p>0.005). The mean IFN-γ levels were statistically significantly higher in patients with PDR (70.98 pg/ml) and patients with NPDR (46.61 pg/ml) than in nondiabetic patients (22.02 pg/ml). There was a difference in the IFN-γ levels in the vitreous between patients with PDR and patients with NPDR (p<0.005). The MMP-2 and MMP-9 concentrations in the vitreous were not different between all groups (p>0.05). There was a correlation between the IFN-γ and TNF-α levels. We investigated the statistically significantly decreased levels of adiponectin in the proliferative (p<0.05) and nonproliferative (p<0.05) diabetic eyes compared to the nondiabetic eyes. CONCLUSIONS: Increased levels of IFN-γ and TNF-α in the vitreous were found in patients with diabetes compared to nondiabetic patients. Decreased levels of adiponectin in the vitreous were found in patients with diabetes compared to nondiabetic patients. The data support the hypothesis that inflammation is associated with diabetic retinopathy.