Abstract
Purpose :
Current treatments for wet age-related macular degeneration (AMD) involve regular anti-VEGF intravitreal injections; thus, far less invasive treatment is desired. We developed an inhibitor of microtubule-associated End Binding Protein 3 named EBIN which inhibits pathological calcium releases in endothelial cells and prevents choroidal neovascularization (CNV) in both mouse and non-human primate models of AMD. Since previous work demonstrated progressive decreases in chromatin accessibility in patients with late-stage of AMD, here we analyze the effects of EBIN in chromatin accessibility of different retinal cell types using single nuclei-assay for transposase-accessible chromatin (snATAC) sequencing in non-human primates.
Methods :
CNV was induced via laser photocoagulation in monkey eyes. Monkeys then received 30 μL topical formulations of EBIN or vehicle in each eye after laser-induced CNV twice daily for 7 days and once a day for another 14 days. Then monkey retina/choroid were subjected to nuclei isolation used for snRNA- and snATAC- sequencing. Lastly, further bioinformatic analysis and validations of the sequencing data were performed using immunofluorescent staining of CNV lesions.
Results :
Using snATAC-seq transcriptome data, we detected 22 distinct clusters corresponding to different retinal cell types characterized via well-known markers. Unknown ATAC clusters were manually characterized by Pearson Correlation using our snRNA-seq data. Analysis of differential peaks within each cluster revealed a widespread opening of chromatin characterized by an increase in promoter peaks in all cell types detected. The change in chromatin accessibility was associated with increased acetylation of lysine 27 of histone 3 (H3K27ac) nuclear signals (p<0.0001, n=4) but not histone 4 lysine 8 (p=0.0956, n=4) assessed with immunofluorescent staining of choroidal neovascular lesions. Additional comparison of our snATAC-seq transcriptome data against a published AMD GWAS dataset showed that EBIN does not open chromatin of genes involved in AMD progression (Spearman Correlation = -0.06).
Conclusions :
EBIN induces a widespread increase of chromatin accessibility in cells comprising CNV lesions including metabolically active endothelial cells by increasing the acetylation of H3K27. Testing EBIN in clinical trials could provide AMD patients with an alternative non-invasive (topical) treatment.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.