Abstract
Abstract: :
Purpose: Since vitrectomy resolves diabetic macular edema (DME) in some patients without traction, causative chemical mediators are presumably present in the vitreous. VEGF or erythropoiethane has been investigated as a possible inducer, but previous studies focused on a single protein. We analyzed the DME-related proteins en masse via two-dimensional electrophoresis (2-DE) and mass spectrometry (MS). Methods: At the beginning of vitrectomy prior to fluid infusion, 300µ l vitreous was sampled from patients with DME, pre-proliferative diabetic retinopathy without DME (PPDR), proliferative diabetic retinopathy (PDR), macular hole (MH) and epiretinal membrane (ERM). After the total protein contents were determined for vitreous samples via the Bradfold method, 2-DE was performed. The spots portraying specific DME expressions were determined via analysis software (PDQUESTTM). Database search with SWISS-2DPAGE and mass spectrometry analysis were performed. Results: Protein concentrations (mean ± SD) of the vitreous were 848 ± 540, 967 ± 395, 1856 ± 560 and 5552 ± 785 µg/ml in MH/ERM (n = 11), PPDR (n = 3), ME (n = 16) and PDR (n = 15), respectively. Two-dimensional electrophoresis revealed 23 spots expressed exclusively in DME when compared with PPDR. Furthermore, 2 spots manifested expressions fourfold those of PPDR. Of these, the spot with highest expression coincided with plasma retinol-binding protein (PRBP) on the SWISS-2DPAGE database. Other two markedly increased spots analyzed with mass spectrometry, did not match any known protein. Conclusion: Vitreous protein concentrations increased with severity of diabetic retinopathy. DME showed higher protein concentration than PPDR. Candidate molecules such as PRBP for DME can exist in premacular vitreous.
Keywords: 388 diabetic retinopathy • 460 macula/fovea • 629 vitreous