microRNA-96 promotes vascular repair to protect against oxygen-induced retinopathy: a novel uncovered vasoprotective function

Abstract

Purpose : Vascular degeneration is a hallmark in the pathogenesis of oxygen-induced retinopathy (OIR). Dysregulation of microRNAs (miRs), key regulators of genes expressions, has been implicated in the regulation of ocular angiogenesis. However, miRNAs specific functions in impaired vascular development during OIR are poorly understood. Herein, we identified miR-96 as one of the most highly expressed miRNAs in the retina and choroid during vascular development and investigated the potential role of miR-96 on microvascular degeneration in a rat OIR model.

Methods : Next generation sequencing (NGS) was used to perform a total miRs profile in the retina and choroid in healthy and OIR rats. miR-96 expression and the downstream mechanisms were analyzed by qRT-PCR and western blot. In vitro: angiogenic effects (migration/tubulogenesis) of miR-96 mimic or antagomir during normoxic or hyperoxic conditions were evaluated on human retinal endothelial cells (ECs). In vivo: OIR rat pups (80% O₂ from P5 to P10) where intravitreally supplemented with miR-96 mimic (1 mg/kg) or a control-miR at P5 and retinal and choroidal tissues collected from P6 to P10 to evaluate vascular density by immunostaining.

Results : miR-96 expression was strongly downregulated in the retina and choroid of OIR rats during the phase of microvascular degeneration in comparison to control rats. Similarly, ECs subjected to hyperoxia showed a significant downregulation of miR-96 leading to a robust angiogenic impairment (tubulogenesis and migration), also observed on ECs transfected with an antagomiR-96. Interestingly, ECs stimulated with miR-96 regulate positively the expression of several key angiogenic factors including VEGF and ANG-2, increased ECs angiogenic activity and protect against hyperoxia-induced ECs dysfunction. In vivo, OIR rat pups intravitreally supplemented with miR-96 mimic displayed a significantly preservation of retinal/choroidal microvessels compared to the control at P10 and were consistent with the maintenance of physiologic levels of VEGF and ANG-2 in the OIR retina.

Conclusions : This study demonstrates that miR-96 regulates the expression of angiogenic factors associated to the maintenance of retinal and choroidal microvasculature, and intravitreal supplementation of miR-96 mimic could constitute a novel therapeutic strategy to improve vascular repair in OIR and other ischemic retinopathies.

This is a 2020 ARVO Annual Meeting abstract.