Modulation of steroid pathway to preserve corneal transparency

Abstract

Purpose: Corneal neovascularization (CN) is a major cause of blindness worldwide. We previously showed that endothelial mineralocorticoid receptor (MR) contributed to CN in mice. In this study, we investigated the mechanisms of action of MRA in a rat model of limbal deficiency.Methods: CN was induced in Lewis rats by total corneal de‐epithelialization and limbal scratching. Spironolactone (SPL, 25 mg/kg) or eplerenone was administered daily. Control eyes received vehicle. Rats were euthanized at day 3 and 7, and corneas were dissected for transcriptomic analysis. Proteins extracted from corneas at day 7 were used for western blot. Corneal innervation was evaluated by immunostaining of TUBB3 on corneal flat mounts at day 16. Corneal morphology and CN were assessed in vivo by Micron III optical coherence tomography and fluorescein angiography at day 14.Results: MR antagonists (MRA) favoured epithelial regeneration and nerve growth, reduced corneal angiogenesis, edema and inflammation in a rat model of CN. Transcriptomic analysis showed 75 differentially expressed genes in SPL groups. Gene set enrichment analysis highlighted pathways including wound healing and differentiation, inflammatory and immune responses, hypoxia, angiogenesis and neuroprotection. SPL upregulated Dcn, Col1a1, Timp2 and downregulated Lrg1 at day 3, and induced Pedf at day 7. Increase in DCN protein by SPL was confirmed by western blot.Conclusions: MRA regulates genes/proteins involved in anti‐inflammatory and anti‐angiogenic processes, and improves corneal re‐innervation in CN model. Dcn is one of the downstream regulated targets.