Abstract
Purpose :
Ischemic proliferative retinopathies, like retinopathy of prematurity and diabetic retinopathy, are often blinding and treatment options are limited. Current treatments focus primarily on reducing pathological neovascularization (NV) in the second phase of disease without addressing vessel loss in the first phase. We aimed to investigate the latter by assessing the role of REV-ERBα, a nuclear receptor and transcriptional repressor with a cellular cytoprotective effect, in promoting vessel regeneration in a mouse model of oxygen-induced ischemic retinopathy (OIR).
Methods :
Wild-type (WT) and systemic REV-ERBα knockout (KO) mice were analyzed for developmental retinal angiogenesis at post-natal day (P) 5 and P10 for superficial and deep vessel network. In OIR, mice were kept in 75% oxygen from P7-P12 and returned to room air until P17. Vascular morphology was assessed in retinal flat mounts with isolectin (endothelium marker) staining. The effects of REV-ERBα on angiogenesis and endothelial cell (EC) function were analyzed in sprouting assays of aortic rings isolated from REV-ERBα KO mice and in human retinal microvascular endothelial cells (HRMECs) treated with REV-ERBα agonists (SR9009 and SR9011). Expression levels of potential REV-ERBα target genes involved in angiogenesis and antioxidant defense were analyzed in HRMECs and mouse retinal tissue.
Results :
REV-ERBα KO retinas displayed normal developmental angiogenesis when compared to WT, with no significant difference observed in superficial vascular area at P5 or in deep layer vessel morphology at P10. In the OIR model, REV-ERBα KO mice showed a substantially greater area of retinal vaso-obliteration at both P12 and P17, as well as a substantially greater area of pathological NV at P17. REV-ERBα KO aortic ring explants had significantly reduced sprouting when compared to WT. Treatment with REV-ERBα agonists increased vascular tube formation in HRMECs in both normal and H2O2-treated conditions. Expression of Nrf2, a master regulator of antioxidant response, was significantly decreased in REV-ERBα KO retinas, while in HRMECs treated with REV-ERBα agonists, Nrf2 expression was increased.
Conclusions :
Our results suggest that genetic deficiency of REV-ERBα may impede vascular regeneration in retinopathy, without impacting developmental angiogenesis, possibly through dysregulation of EC oxidative stress response.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.