Vitreous Levels of Soluble Vascular Adhesion Protein-1 and Prorenin in Proliferative Diabetic Retinopathy

Abstract

Purpose: Soluble vascular adhesion protein (VAP)-1, shedding form of leukocyte adhesion molecule VAP-1, functions as an enzyme that facilitates oxidative stress and advanced glycation end products formation, both of which are implicated in the pathogenesis of diabetic retinopathy (DR). Prorenin, the key ligand to activate the receptor-associated prorenin system (RAPS) and promote retinal inflammation and neovascularizaion, also participates in the development of proliferative diabetic retinopathy (PDR). In this study, we explored the correlations between protein levels of soluble VAP-1 (sVAP-1) and the constituents of RAPS in the vitreous fluid obtained from patients with PDR.

Methods: Undiluted vitreous samples were collected from 16 eyes of 16 patients with PDR (aged 61.0±6.2 y/o), who underwent pars plana vitrectomy for vitreous hemorrhage and tractional retinal detachment. The samples containing gross hemorrhage were excluded. For a control, vitreous samples were obtained from age-matched non-DR subjects with idiopathic macular hole or epiretinal membrane (11 eyes of 11 patients, aged 63.8±4.9 y/o). Vitreous levels of sVAP-1, prorenin and soluble prorenin receptor (s(P)RR) were measured by enzyme-linked immunosorbent assay.

Results: In accord with the previous reports, vitreous levels of sVAP-1 (8.98±1.76ng/ml), prorenin (173.56±27.86pg/ml) and s(P)RR (3.28±0.42pg/ml) in PDR group were significantly elevated compared with those in non-DR group (sVAP-1, 0.93±0.26ng/ml; prorenin, 62.33±14.99pg/ml; s(P)RR, 0.60±0.22pg/ml; P<0.01 each). In PDR group, there was a significant positive correlation between sVAP-1 and prorenin (r=0.740, P<0.01). By contrast, there was no correlation between sVAP-1 and prorenin in non-DR group (P=0.16).

Conclusions: Our data suggest the interaction between sVAP-1 and RAPS in eyes with PDR.

Keywords: 499 diabetic retinopathy