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.
ObjectiveTo investigate the effects of Krüppel-like factor 7 (KLF7) on the survival of retinal ganglion cells (RGCs) and electroretinogram (ERG) after retinal ischemia-reperfusion (RIR) injury in mice.MethodsA total of 126 male C57BL/6J mice were randomly divided into normal group, RIR group, normal-KLF7 group, normal-green fluorescent protein (GFP) group, RIR-KLF7 group and RIR-GFP group. At the age of 8 weeks, mice of normal-KLF7 group and RIR-KLF7 group were intravitreally injected 1ul of 1.0×1012 vg/ml adeno-associated virus overexpressing KLF7 (AAV2-KLF7-GFP). Mice of normal-GFP group and RIR-GFP group were injected adeno-associated virus of AAV2-GFP with the same titer. At the age of 11 weeks, RIR injury was induced in mice of RIR group, RIR-KLF7 group and RIR-GFP group, and intraocular pressure was measured. Retinal cryosections were used to access the efficacy of virus transfection 4 weeks after AAV2-KLF7-GFP transfer. 7 days after RIR injury, RGCs’ survival rate was observed and quantified by immunofluorescent staining. ERG was performed to observe the differences in amplitudes and incubation period of scotopic ERG a-, b-wave, oscillatory potentials (Ops), photopic negative responses (PhNR). Optomotor response was performed to observe the differences of visual acuity. Expression of KLF7 was detected by western blot 4 weeks after AAV2-KLF7-GFP transfer.ResultsCompared with normal group, RGCs’ survival rates, amplitudes of ERG a-, b-wave, Ops, PhNR and visual acuity of mice in RIR group were decreased, and the differences were statistically significant (t=12.860, 7.157, 5.735, 8.953, 4.744, 9.887; P＜0.05). With the increase of light intensity, the amplitudes of scotopic ERG a- and b-wave were gradually increased while the incubation period was gradually shortened. Compared with RIR group, RGCs’ survival rates, amplitudes of ERG a-, b-wave, Ops, PhNR and visual acuity of mice in RIR-KLF7 group were increased, and the differences were statistically significant (t=6.350, 3.253, 3.695, 5.825, 5.325, 4.591; P＜0.05). Protein level of KLF7 was up-regulated in normal-KLF7 group than those in normal group, and the difference was statistically significant (t=4.105, P＜0.01).ConclusionOverexpression of KLF7 can improve RGCs’ survival rates and preserve the electrophysiological function.
ObjectiveTo investigate the effect of heat shock protein B8 (HspB8) downregulation on retinal ganglion cell (RGC) and retinal function in the mice model of optic nerve injury (ONC).MethodsAdeno-Associated Virus (AAV) 2 AAV2-shHspB8-GFP was constructed to knockdown HspB8. 66 adult male C57/BL6 mice were randomly divided into the control group, the ONC group, the AAV2-shHspB8 group, the ONC+AAV2-shHspB8 group, and the ONC+AAV2- GFP group. There were 10, 20, 16, 10 and 10 mice respectively, and both eyes were used as experimental eyes. Western blot was used to evaluate the expression of HspB8 on day 3 and 7 after ONC. By GFP immunofluorescence staining, the efficacy of AAV2-shHspB8-GFP transfer was accessed. Moreover, it was possible to identify functional and RGC survival differences between groups by optomotor response (OMR), dark adapted full-field flash electroretinogram (ff-ERG), oscillatory potentials (OPs), photopic negative response (PhNR) and retinal flat-mount RGC counting 5 days after ONC. Comparisons between two groups were made using Mann-Whitney U test, unpaired t-test, unpaired t-test with Welch’s correction, one-way ANOVA, and Bonferroni t test.ResultsCompared with the control group, the expression of HSPB8 protein in the retina of mice in ONC3 group was significantly increased, and the difference was statistically significant (F=43.63, P＜0.01). Compared with the control group, the ONC group showed obviously lower visual acuity (P＜0.01), lower a-wave, b-wave, OPs, PhNR amplitude, longer b-wave latency (P＜0.05), and the survival rates of RGC in ONC3 group, ONC5 group and ONC7 group decreased in a time-dependent manner(F=384.90, P＜0.01). Transfection of AAV2 efficiency was highest on 4 weeks after IVT. Besides, there was no significant differences between the control group and the AAV2-shHspB8 group on visual acuity, ff-ERG, OPs, PhNR and RGC survival (P>0.05). In comparison of the control group, we found that RGC survival of the ONC5+AAV2-shHspB8 group was significantly elevated (F=10.62, P＜0.01).ConclusionsExpression of HspB8 on the retina can be induced by ONC. The investigation of RGC counting, visual acuity, and ff-ERG revealed that optic nerve injury destructed functionality of mice retina and resulted to RGC death ultimately. The Most crucial finding of this research is that HspB8 knockdown had a neuroprotective effect in RGC after ONC.