Identification of vitreous proteins in retinopathy of prematurity.

Retinopathy of prematurity (ROP) is a disorder of blood vessels in the retina developed in premature infants and the leading cause of the blindness in children. Proteomic analysis was performed to identify vitreous proteins specific to patients with ROP. Vitreous humor samples were obtained from three patients with ROP and two patients with congenital cataract, the latter included as a control group. The vitreous samples were separated by 2D-PAGE and the proteins running as definitive spots were identified by MALDI-TOF MS spectrometry. We identified 13 and 6 proteins in the vitreous from ROP and cataract patients, respectively. Albumin, transferrin, pigment epithelium-derived factor (PEDF) and transthyretin were found in both patient groups. In the samples from ROP patients, PEDF and transthyretin levels were lower than in those from cataract patients, and retinol binding protein 3 and prostaglandin D synthase were not detected. Of the 13 proteins, 9 proteins including α-2-macroglobulin, ceruloplasmin, α-fetoprotein, vitamin D-binding protein, α-1-antitrypsin, α-1-β-glycoprotein, hemopexin, apolipoprotein A-1 and A-lV were found in vitreous samples of only the ROP patients. PEDF has anti-angiogenic and neurotrophic functions. Whether PEDF is increased or decreased in diabetic retinopathy has been controversial but we observed lower PEDF in the ROP samples than in the controls. The proteins specific to or decreased in ROP, if confirmed in future studies, may provide clue to understanding its pathogenesis.