Proteomics of Vitreous Fluid

Vitreous and serum samples were obtained from subjects with diabetic retinopathy (DR; 33 cases) and idiopathic macular hole (MH; 26 cases), at the time of pars plana vitrectomy. The expressed proteins were separated by 2D gel electrophoresis. Separated protein spots were then visualized by silver staining and analyzed by mass spectrometry. For the MH vitreous samples, more than 400 spots were detected on 2D gels, of which 78 spots were identified as 18 unique proteins, including pigment epithelium-derived factor (PEDF), prostaglandin-D2 synthase, plasma glutathione peroxidase, and interphotoreceptor retinoid-binding protein (IRBP), which were not identified in the corresponding serum samples. For the DR vitreous samples, more than 600 spots were detected on gels, and 141 spots were identified as 38 unique proteins, some of which were derived from serum. Enolase and catalase were identified among four detected spots; neither of them was found in MH vitreous or DR serum samples. The increased protein expression observed in DR vitreous samples may be due to barrier dysfunction and/or production in the eye.