Molecular analysis of the inner blood-retinal-barrier and its dysregulation in diabetes

Abstract

Endothelial cells line the inner walls of the retinal vasculature, forming the inner-blood retinal barrier (iBRB), a restrictive physiological barrier. In diabetic macular oedema (DMO) the dysfunction of these cells contributes to iBRB impairment, yet our understanding of the molecular biology of the iBRB and how this is changed in DMO remains incomplete. In this study, we performed bulk RNA-seq to analyse barrier gene expression in human retinal microvascular endothelial cells (HRMECs) under conditions mimicking key aspects of the diabetic milieu. We identified key changes in gene expression following long-term high glucose (HG) exposure, compared to short term exposure to VEGF. Furthermore, several over-represented TF-binding sites were found in barrier genes downregulated in hyperglycaemia. Follow-up studies revealed that TCFL5 is a key regulator of barrier gene expression in HRMECs; however, this TF did not mediate the downregulation of barrier genes under HG conditions. Nanopore RNA sequencing was then undertaken, revealing novel findings of increased RNA modification sites in barrier genes after long-term HG exposure. Given the significant side effects and late-stage focus of current DMO treatments, there is an urgent need for therapies with better outcomes. By enhancing our understanding of the molecular biology of the iBRB and its alterations under diabetic-like conditions, this PhD thesis provides a strong foundation for future studies aimed at developing more effective treatments for DMO.

Date of Award	Jul 2025
Original language	English
Awarding Institution	Queen's University Belfast
Supervisor	David Simpson (Supervisor), Tim Curtis (Supervisor) & Josy Augustine (Assistant Supervisor)