Topical NorLeu³ Angiotensin (1-7) Promotes Non-Fibrotic Healing in Ocular Globe Injury Model

Abstract

Purpose : Open globe injuries like those sustained in the combat theater result in corneal scarring that can permanently affect visual acuity. We have previously shown that topical corneal delivery of NorLeu³-Angiotensin (1-7) (NLE), a Mas agonist, can stimulate the protective axis of RAS and promote anti-inflammatory and antifibrotic healing. Here, we identify the optimal NLE concentration leading to clear corneal healing in a 6 mm stellate open globe rabbit injury model.

Methods : New Zealand Black rabbits received 6 mm full-thickness stellate lacerations OD on Day 0 and were randomly assigned to treatment groups (n=7/group)—vehicle, 0.1%, 0.3%, or 0.45% NLE—and treated with two drops (~100 μL) given twice daily (BID) for 28 days. Intraocular pressure (IOP), Seidel’s test, RetCam/slit lamp examination, anterior-segment optical coherence tomography (AS-OCT), and confocal imaging via HRT-III were performed at designated times throughout the study. On Day 28, corneas were collected for histological and molecular interrogation (e.g., RT-PCR and RAS metabolomics).

Results : Animals treated with 0.1% NLE were able to achieve Seidel’s negative most rapidly, where 100% of rabbits achieved Seidel’s negative by 24 hours. In addition, 0.1% NLE treatment was able to minimize corneal haze as compared to vehicle treatment (p<0.05), indicating the promotion of clear corneal healing. Masson’s trichrome staining of corneal sections revealed significant increased collagen formation with 0.1% NLE when compared to 0.3% and 0.45% NLE treatment groups (p<0.05). Additionally, the majority of 0.1% NLE treated corneas achieved pre-injury corneal architecture as revealed in HRT-III. Corneal gene expression of RAS receptor genes showed that 0.1% NLE treatment was able to downregulate MasR. These clinical and gene expression findings correlated with concentration of NLE and RAS peptide metabolomics.

Conclusions : Clear corneal healing is key in restoring visual acuity after injury, where precise alignment of the extracellular matrix and cells is critical to maintaining transparency. Treatment with 0.1% NLE accelerated corneal healing, restored corneal architecture, and increased collagen formation and alignment, while reducing corneal haze. This dataset shows 0.1% NLE treatment can more rapidly accelerate complete clear corneal healing in a stellate corneal injury model.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.