Abstract
Purpose :
Retinopathy of prematurity (ROP) is a major cause of vision loss and blindness in children. In ROP, the onset of neovascularization (NV) is at around 32-weeks gestational age, regardless of gestational age at birth, which coincides with the development of rod outer segments and full rod function. Photoreceptors may play an important role in ROP pathogenesis. Yet, the molecular and cellular mechanisms through which photoreceptors control retinal NV in ROP are largely unknown. We aim to investigate the role of photoreceptors in controlling retinal angiogenesis via suppressor of cytokine signaling 3 (SOCS3).
Methods :
The Cre/LoxP system was used to generate rod photoreceptor specific Socs3 knockout mice (Socs3 cKO) by crossing Socs3 flox/flox mice with Rhodopsin improved Cre mice (Rho-iCre) and Socs3 overexpression mice (Socs3 cOE) by crossing Socs3 OE flox/flox mice with Rho-iCre mice. The oxygen induced retinopathy (OIR) mouse model was used as a ROP preclinical model. Mice were exposed to 75% oxygen from postnatal day (P)7 to P12 and returned to room air from P12 to P17. Retinas were enucleated, fixed, and stained with endothelial cell marker isolectin B4 at P17 for phenotypical analysis. NV and vaso-obliteration (VO) was quantified using Image J. Real-time PCR and western blot were used to validate the efficacy of Socs3 overexpression and knockout. Immunohistochemistry was used to determine protein localization in the retina. Results are reported as mean ± SEM, and statistical analyses were performed with GraphPad Prism (v8.0).
Results :
In the OIR model, SOCS3 expression was highly induced in the photoreceptor layer. The efficacy of photoreceptor Socs3 overexpression and knockout was validated. Cre recombination of Socs3 in the outer nuclear layer of the retina was confirmed using Rho-iCre driven mTmG reporter mice. In the OIR model, SOCS3 deficiency in rod photoreceptors significantly increased NV by 25% (p<0.01, n=18-20) without influencing VO (p>0.05) compared to controls. Conversely, SOCS3 overexpression significantly decreased NV by 28% (p<0.01, n=17-20) but not VO (p>0.05) compared to littermate controls. Pharmacologic treatment with SOCS3 activator naringenin suppressed retinal neovascularization.
Conclusions :
Our data strongly suggests that rod photoreceptor SOCS3 mediates neovascularization in the OIR model. Activation of photoreceptor SOCS3 may be a potential therapeutic for treating retinal angiogenesis.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.