Protein redox status in the vitreous of diabetic patients

PURPOSE: Little is known about the redox status of the vitreous proteins in diabetic subjects. Therefore, the aim of this study was to invastigate the content of sulfhydryl proteins (P-SH), protein mixed disulfides (PB-SH) and carbonyl proteins(DNPH) in the vitreous of diabetic and non diabetic subjects.METHODS: 27 subjects were included in the study (A=7 healthy controls, B=10 type-2 diabetic subjects with proliferative retinopathy; C=10 type-2 diabetic subjects with non-proliferative retinopathy). The vitreous was centrifuged and the supernatant analyzed for PB-SH and DNPH, indices of oxidatively demaged proteins, and P-SH, index of reduced status of the proteins.RESULTS:A significant lower content of P-SH was found in the vitreous of diabetics (9-7;±2.4 vs 17±5.4 nmol/mg prot, p 0.001), especially when a retinal complication was present(7.1±2.1 nmol/mg prot, p 0.02 compared to C).Moreover an increased PB-SH and DNPH was noticed in diabetic subjects compared to healthy controls (p 0.001). Yet, these parameters resulted to be particularly altered when diabetes was associated with retinal disease.CONCLUSIONS: This study shows an alteration of the protein redox status in subjects affected by diabetes mellitus.Vitreous proteins were found to be oxidized to a larger extend in the presence of retinal disease.