Vitreous levels of Vascular Adhesion Protein-1 in Proliferative Diabetic Retinopathy

Abstract

Purpose: : Vascular adhesion protein-1 (VAP-1) is a dual function molecule, as a leukocyte adhesion molecule and as an ectoenzyme catalyzing oxidative deamination leading to generation of hydrogen peroxide, which in turn causes oxidative stress. The aim of this study is to investigate the relationship between the protein levels of soluble VAP-1 and increased oxidative stress in the vitreous of patients with proliferative diabetic retinopathy (PDR).

Methods: : Undiluted vitreous samples were collected from 25 eyes of 25 patients with PDR ranging from 52 to 82 years of age (mean 60.6), who underwent pars plana vitrectomy for vitreous hemorrhage and tractional retinal detachment. The samples containing gross hemorrhage were excluded from the current study. For a control, vitreous samples were obtained from age-matched non-diabetic subjects ranging from 56 to 73 years of age (mean 64.0) with idiopathic macular hole (8 eyes) and idiopathic epiretinal membrane (8 eyes). Vitreous levels of soluble VAP-1 and hexanoyl lysine (HEL), a marker of oxidative stress, were measured by enzyme-linked immunosorbent assay.

Results: : Vitreous level of soluble VAP-1 in the eyes with PDR (8555.8±1235.6 pg/ml) was significantly higher than that in the control eyes (893.1±194.5 pg/ml, p<0.001). Furthermore, protein concentration of soluble VAP-1 was positively correlated with HEL in the vitreous samples of PDR (r=0.416, p<0.05).

Conclusions: : Our data indicate that soluble form of VAP-1 is associated with the deterioration of oxidative stress, critical feature in the pathogenesis of PDR.

Keywords: diabetic retinopathy • oxidation/oxidative or free radical damage • inflammation