ObjectiveTo observe the inhibitory effect of lentivirus mediated small interference RNA (siRNA) targeting cyclic adenosine monophosphate responsive element binding protein 1 (CREB1) on retinal neovascularization (RNV) in mice. MethodsCREB1 siRNA construct was created, screened and packaged to produce CREB1 RNAi-lentivirus. One hundred and forty (5-day-old) C57BL/6J mice were randomly divided into 4 groups including normal group, oxygen induced retinopathy (OIR) group, empty vector group and CREB1 therapy group with 35 mice in each group. Mice in the normal group were kept in normal room air, while in the other three groups retinal neovascularization was induced by hypoxia on postnatal day 7 (P7). The mice in the OIR group were not treated. The mice in the vector group received intravitreal injection of lentivirus-green fluorescent protein (lenti-GFP, 1 μl), and the CREB1 therapy group received CREB1 RNAi-lentivirus (1 μl) on P5.The proliferative neovascular response was quantified by counting the vascular cell nuclei extending breaking through the internal limiting membrane (ILM) and fluorescent angiography. The areas of RNV and non-perfusion region were calculated. The expression of CREB1, phosphorylated-CREB1 (P-CREB1) and vascular endothelial growth factor (VEGF)-A levels, Akt and phosphoinositide 3-kinases (PI3K) in retinas were measured by reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blot. ResultsThe number of vascular cell nuclei breaking through the ILM of the OIR group and the empty vector group increased significantly compared with the normal group (P<0.05), while obviously decreased in the CREB1 therapy group compared with the OIR group and the empty vector group(P<0.05). The area of RNV and non-perfusion region of the OIR group and the empty vector group increased significantly compared with the normal group, while obviously decreased in the CREB1 therapy group compared with the OIR group and the empty vector group. The difference of area of RNV and non-perfusion region among 4 groups were significant (F=67.220, 110.090; P<0.05). The mRNA expression of CREB1 and protein expression of P-CREB1, the mRNA and protein expression of VEGF-A, Akt, PI3K in the retina were increased significantly in the OIR group and the empty vector group as compared with the normal group, while decreased significantly in the CREB1 therapy group as compared with the OIR group and the empty vector group. The difference of mRNA expression of CREB1, VEGF-A, Akt, PI3K in the retina among 4 groups were significant (F=6.087, 5.464, 6.191, 8.627; P<0.05). The protein expression of P-CREB1, VEGF-A, Akt, PI3K in the retina among 4 groups were significant (F=162.944, 13.861, 19.710, 22.827; P<0.05). ConclusionRNV in the mice is significantly inhibited by intravitreal injection of lentivirus-mediated CREB1 down-regulation.
Objective To observe the effects of bevacizumab on aquaporin 4 (AQP4) expression in human retinal Muuml;ller cells in vitro under hypoxia. To explored the mechanism of treating retinal edema with bevacizumab. Methods Human Muuml;ller cells were cultured using the enzymatic digestion method. Transmission electron microscopic analysis and immunofluorescence staining identified Muuml;ller cells. With semi-quantitative reverse transcription polymerase chain reaction (RT-PCR), the expression of AQP4 mRNA and vascular endothelial growth factor （VEGF） mRNA in Muuml;ller cells cultured under different concentration of COCl2 for different hours were observed. The expression of AQP4 mRNA in Muuml;ller cells cultured using CoCl2 precultured with 200 mu;g/ml bevacizumab was measured. Results More than 95% of primary cells showed positive reaction to glial fibrillary acidic protein, glutamine synthetase, vimentin and alpha;-smooth muscle actin with immunofluorescence staining. Characteristic 8-10 nm intracellular filaments could be seen in the cytoplasm viewed with transmission electron microscopy. The results using RT-PCR showed that CoCl2 increased the AQP4 and VEGF mRNA expression in Muuml;ller cells in a dose and time dependent manner (r=0.952, 0.954;P＜0.05). The expression of AQP4 mRNA in Muuml;ller cells was increased by VEGF (F=12.43,P＜0.05). The expression of AQP4 mRNA was significantly decreased by bevacizumab (F=2 370.37，P＜0.05). Conclusion Bevacizumab can down-regulate the expression of AQP4 mRNA in human Muuml;ller cells under hypoxic conditions partially by VEGF path, which may be a mechanism for treating retinal edema with bevacizumab.