Abstract
Purpose :
Corneal neovascularization (CNV) is a major cause of blindness worldwide. Topical steroids are widely used to treat CNV, but the results are highly variable. Glucocorticoids act through binding to both glucocorticoid (GR) and mineralocorticoid receptors (MR). MR overactivation contributes to retinal and choroidal neovascularization, and endothelial MR invalidation reduces CNV in mice. We thus aimed to evaluate the pharmacological effects of MR antagonism in CNV.
Methods :
CNV was induced in one eye of Lewis rats by a 360° circumstance total corneal de-epithelialization and limbal scratching. Rats were injected subcutaneously with MR antagonist (MRA) spironolactone 25mg/kg/day or vehicle for 14 days. Corneal morphology and thickness were assessed in vivo at day 3, 7 and 14 using Micron III optical coherence tomography (OCT). Corneal re-epithelialization was evaluated by fluorescein staining under slit lamp at day 3 and 7. Fluorescein (FA) and indocyanine green angiographies (ICG) were performed at day 14 to evaluate the surface of CNV. Rats were sacrificed at day 16 and eyes removed for immunostaining of ED1, IBA1 and GSI-B4. Peripheral cornea and tissues adjacent to limbus were also dissected at day 3 and day 7 for quantitative PCR and transcriptomic analysis. A more specific MRA eplerenone (200mg/kg/day in chew for 14 days) was also used to confirm the effect of MR antagonism.
Results :
Spironolactone significantly reduced the CNV and corneal thickness compared to vehicle. There is no difference in corneal re-epithelialization between spironolactone and vehicle. Spironolactone reduced infiltration of ED1 and IBA1 positive inflammatory cells and decreased the isolectin-positive neovascular surface in the cornea. The transcriptomic signatures showed 212 differentially expressed genes (26 up-regulated and 186 down-regulated) involved in corneal wound healing and differentiation, infectious responses, inflammatory and immune responses, myogenesis and hypoxia. The qPCR showed an up-regulation of GR in spironolactone treated group tilting the GR/MR balance in favor of GR pathway. Eplerenone confirmed the anti-angiogenic effect of MRA.
Conclusions :
MRA is anti-angiogenic, anti-inflammatory, and anti-edematous in rat CNV. The potential additive effect of MRA and glucocorticoids on CNV will be further tested.
This is a 2021 ARVO Annual Meeting abstract.