Inhibition of Retinal Neovascularization by New RNAi Agent Targeting Periostin

Abstract

Purpose: We have previously reported that periostin (PN) is preferentially expressed in epiretinal fibrovascular membranes and new RNAi agent targeting PN (NK0144) can inhibit both choroidal neovascularization and fibrosis. The purpose of this study was to investigate the role of PN in retinal neovascularization and the effect of NK0144 on retinal neovascularization.

Methods: We generated a mouse model of oxygen-induced retinopathy (OIR) using C57BL/6J wild type (WT) and PN knock out (KO) pups. The expression of PN in retinas from OIR mice were quantified by real-time RT-PCR and ELISA. The localization of PN was evaluated by immunohistochemical analysis. We compared neovascular tufts areas using retinal flat mounts between WT and KO mice. One μL PBS containing 10 pmol of NK0144 was intravitreally injected to WT mice immediately after exposure to high-oxygen and the areas were quantified. In vitro, the effect of PN on proliferation, migration, and tube formation of human retinal endothelial cell (HREC) were examined.

Results: PN expression in retina of OIR mice was significantly increased and reached a peak at postnatal day (P) 17 when retinal neovascularization also reached its peak. Immunohistochemical analysis showed that PN was colocalized with CD31 and α-SMA positive cells in neovascular tufts, and some of the F4/80 positive cells in retina. Neovascular tufts areas were significantly reduced by about 60% in periostin KO mice compared to WT mice (p<0.05). Those in mice treated with NK0144 were also significantly smaller by about 40% compared with control mice (p<0.05). PN promoted proliferation, migration, and tube formation of HREC through integrin αV-mediated FAK/Akt phosphorylation (p<0.05). Finally, NK0144 significantly inhibited tube formation of HREC (p<0.05).

Conclusions: These results suggest that PN may promote retinal neovascularization. NK0144 may be a potential therapeutic agent for proliferative diabetic retinopathy.