Remarkable inhibition of corneal scarring by Id3 gene therapy in a preclinical rabbit in vivo model

Abstract

Purpose : Inhibitor of differentiation (Id) proteins is helix-loop-helix (HLH) transcriptional repressors. The Id3 gene, a member of the Id gene family, governs the expression of transforming growth factor-beta (TGFβ)-mediated cell differentiation. In the face of corneal insults, including mechanical, chemical and surgical, differentiation results in the process of myofibroblast development and corneal haze formation. The objective of this study was to investigate the potential of Id3 gene therapy to treat corneal fibrosis using established preclinical rabbit in vivo model.

Methods : New Zealand White rabbits were used for in vivo study and corneal fibrosis was produced by the alkali injury. Thirty-minutes after scar formation, cornea received topically either balanced salt solution (BSS), AAV5-naked or AAV5-Id3 gene through customized gene delivery method. Gene therapy effects on corneal fibrosis, and ocular safety was evaluated by slit-lamp microscopy, stereo- microscopy, and Schirmer's test in live animals. qRT-PCR, immunofluorescence, TUNEL assay, and western-blot were used to analyze the inhibitory effects of Id3 gene transfer on corneal fibrosis. Student’s t-test and analysis of variance (ANOVA) were used for statistical analysis.

Results : We demonstrate that a single topical application of AAV5-Id3 in rabbit cornea post-alkali led to a significant decrease in a corneal haze. AAV-5 mediated Id3 gene therapy significantly decreased corneal fibrosis in live rabbits in vivo (Fantes scale was 0.5±0.2 in Id3-treated eyes compared to 2.5±0.5 in naked therapy group; p<0.01). Corneal edema was also significantly higher in naked therapy group as compared to the Id3 gene delivery group (2.1±0.2 fold; p<0.05). Histology data from H&E staining revalidated the clinical imaging data, and showed the relatively higher number of inflammatory cells and altered morphology in the naked therapy group as compared to the Id3 gene delivery groups. mRNA and protein data for both -/+ therapy groups are underway.

Conclusions : Localized topical Id3 gene therapy treats corneal fibrosis and restores transparency in vivo.

This is a 2020 ARVO Annual Meeting abstract.