Apelin silencing exacerbated retinal edema in BRVO rats

Abstract

 

Purpose

 

We recently reported the neuroprotection of apelin peptide for primary rat retinal Müller cells under hypoxia or glucose-deprivation. Therefore we hypothesized that its administration might be a promising protection for ischemic retina. In the present study, we targeted that whether apelin silencing was resistantor susceptible to retinal edema in branch retinal vein occlusion (BRVO) rats.

 

Methods

 

We engineer recombinant HIV-1-based lentiviral vectors (LV) capable of highly efficient and sustained apelin gene-knock down. Apelin-RNAi LV and GFP lentiviral control vectors were delivered by intravitreal injection to the right eyes of Sprague-Dawley rats, whose contralateral eyes served as normal control. Apelin silencing efficiency was confirmed by in vivo fluorescent fundus imaging and western blot 2 weeks after injection. In both LV transfected eyes, BRVO was induced by Ar laser photocoagulation of retinal veins. Also induced were normal right eyes (BRVO group). Optical coherence tomography and electroretinography were performed in above four groups as quantitative assessments of retinal edema and visual function impairment. Meanwhile apelin and its receptor APJ expression were analyzed by immunofluorescence labeling, real time PCR and western blot.

 

Results

 

Apelin mRNA showed down-regulated, however APJ mRNA and protein both up-regulated (p<0.01). There were no significant difference in visual function among 3 BRVO groups, which all manifested decreased βwave amplitude in Rod-Max Response (p<0.001). 3 BRVO groups all presented increased thickness in ganglial cell and inner plexiform layer, inner nuclear layer and outer nuclear layer. Compared with GFP lentiviral control vectors, Apelin-RNAi LV induced severer retinal edema in nerve fiber layer, ganglial cell and inner plexiform layer, as well as inner nuclear layer.

 

Conclusions

 

Apelin expression decreased in Ar laser induced BRVO rats, furthermore, apelin gene silencing exacerbated consequent retinal edema. Hence, exogenous apelin administration may have therapeutic potential in BRVO associated macular edema.

 

 

Fluorescent fundus views of SD rat retina injected intravitreally with apelin-RNAi lentiviral vectors

 

 

Optical coherence tomography images of control retina, BRVO retina, apelin-RNAi LV vectors and GFP lentiviral control vectors transduced retinas

 

Keywords: 749 vascular occlusion/vascular occlusive disease • 538 gene transfer/gene therapy • 552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)