Abstract
Purpose :
Epigenetic modifications, especially microRNA (miR) alterations, play a crucial role in driving retinal endothelial cell dysfunction and subsequent angiogenesis in diabetic retinopathy. This study aims to explore the impact of hyperglycemia and hypoxia on miRNA expression in human retinal endothelial cells (HRECs) to identify potential targets for diabetic retinopathy (DR) treatment.
Methods :
HRECs were treated with high glucose (HG, 25 mM D-glucose), hypoxia (1% oxygen), or a combination of HG and hypoxia for 5 days. Osmotic control (5 mM D-glucose + 20 mM L-glucose) and normoxia (21% O2) served as control conditions. RNA was hybridized to the GeneChip miRNA 3.0 array (Affymetrix), and data were analyzed using Partek Genomic Suites version 6.6, for miR differential expression. Ingenuity Pathway Analysis (IPA, Qiagen) and miRWalk2.0 database was used for pathway and miRNA-target interaction analyses.
Results :
Differential effects were observed for HG and hypoxia on miR expression. HG significantly dysregulated (up and down) 8% of miRs, while hypoxia affected 5% (p < 0.045). The combined effect of HG and hypoxia induced significant changes in 63 miRs compared to HG alone, while hypoxia differentially dysregulated 38 miRs compared to combined treatment by HG and hypoxia. There were 9 miRs implicated in angiogenesis (e.g., miR-124, miR20b, miR718) which were mutually and similarly affected by both conditions. HG and hypoxia treatment differentially dysregulated 45 miRs, with only 2 mutually affected miRs (miR99b-3p and HBII-85-26). MiR-124-3p, critical in regulating hypoxia's effects, showed a -22-fold change in HG-treated HRECs compared to controls but increased by 4-fold in the HG + hypoxia group. MiR-328-3p, not significantly impacted by HG alone, exhibited a -3-fold change in the combined treatment group, suggesting enhanced angiogenesis under hypoxic conditions.
Conclusions :
Pathological neovascularization under hyperglycemic conditions is profoundly influenced by hypoxia. Exposure to high glucose and hypoxia resulted in substantial dysregulation of multiple miRs in HRECs, with some showing distinct effects and others responding similarly, all pivotal in the regulation of angiogenesis. Notably, the upregulation of miR-124-3p and downregulation of miR-328-3p were observed underscoring the potential of these miRs as promising prognostic and therapeutic targets in DR.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.