OTX008 inhibits retinal neovascularization in oxygen-induced retinopathy mice

Abstract

Objective To investigate the inhibitory effects and possible related mechanism of OTX008 [a selective inhibitor of galectin-1 (Galectin-1)] on retinal neovascularization (RNV) in mouse model of oxygen-induced retinopathy (OIR). Methods 7-day-old (P7) C57BL/6J mice were randomly (according to random number table) divided into 4 groups including normal group, OIR group, OIR-OTX008 group and OIR-phosphate buffered saline (PBS) group. To establish the OIR mouse model, mice from all groups except normal group were expose to (75±2)% oxygen for 5 days and then to room air. OIR-OTX008 group received an intravitreal injection of 1 μl (0.25 μg/μl) OTX008 at P12, OIR-PBS group received the equal volume (1 μl) of PBS injection. Mice from 4 groups were euthanized at P17, and retinas were collected for molecular biological analysis and morphological study. RNV was evaluated by counting the number of pre-retinal neovascular nuclei and the whole-mount immunofluorescent staining of mouse retina. Cyrosections of retinas were imaged via confocal microscopy to observe the enrichment of staining of Galectin-1. Protein levels of Galectin-1, Neuropilin-1 and phosphorylation of vascular endothelial growth factor receptor 2 (pVEGFR2) were determined with Western blot. Results At P17, Galectin-1 expressed higher in retinal ganglion cell layer, inner plexiform layer and inner nuclear layer from OIR group and OIR-PBS group than normal group. Galectin-1 expressed less in cryosection retinas from OIR-OTX008 group than OIR group and OIR-PBS group. The numbers of pre-retinal neovascular cell nuclei from OIR group and OIR-PBS group were obviously more than that from normal group (t=9.314,P<0.05). The number of pre-retinal neovascular cell nuclei from OIR-OTX008 group were obviously lower than those from OIR group and OIR-PBS group (t=8.038, 7.774;P<0.05). The RNV tufts area (t=13.250, 12.570), non-perfusion area (t=15.590, 12.430) and hypoxic area (t=9.542, 9.928) from OIR-OTX008 group were significantly smaller than those in OIR group and OIR-PBS group (P<0.05). Protein levels of Galectin-1 (t=24.800, 23.060), Neuropilin-1 (t=4.120, 3.530) and pVEGFR2 (t=25.880, 15.480) in the OIR-OTX008 group were significantly down-regulated than those from OIR group and OIR-PBS group (P<0.05). Conclusion Intravitreal injection of OTX008 inhibits RNV and ameliorates retinal hypoxia in mice model of OIR possibly through down-regulating Galectin-1, Neurolinpin-1 and pVEGFR2. Key words: Retinal neovascularization/prevention c Galectin 1/antagonists i Animal experimentation