Abstract
Purpose :
Diabetic retinopathy is the most common cause of vision impairment in the diabetic population. The disease severity is coupled with retinal angiogenesis in proliferative diabetic retinopathy (PDR). Lysyl oxidase propeptide (LOX-PP) is an 18 kDa protein cleaved extracellularly by bone morphogenic protein-1 (BMP-1) during the biogenesis of lysyl oxidase (LOX). Recent report states that LOX-PP expression is altered upon high glucose treatment and promotes apoptosis of rat retinal endothelial cells. In this study, we examined the anti-angiogenic role of LOX-PP in human retinal endothelial cells (hRECs).
Methods :
The human retinal endothelial cells (hRECs) were isolated from donor eyeballs with informed consent from their relatives. These hRECs were grown in normal glycemic (5 mM) and hyperglycemic (30 mM) medium for 7 days. In vitro angiogenesis assays like proliferation, migration, cell adhesion, and tube formation were performed using rLOX-PP. Cells were harvested after 7 days and western blot analysis was performed to determine changes in the LOX, LOX-PP, AKT activation and BCL-2 expression.
Results :
The human retinal endothelial cells were isolated successfully and characterized by the expression of CD31 and Von willebrand factor (VwF). LOX (p < 0.05) and LOX-PP (p < 0.001) protein expression was significantly upregulated in cells grown in high glucose medium. Exogenously added purified LOX-PP significantly reduced cell proliferation (p < 0.001), cell migration (p < 0.05), cell adhesion (p < 0.001) and tube formation (p < 0.01) in hRECs. Furthermore, rLOX-PP treated hRECs showed significantly decreased AKT (S473) (p < 0.05) phosphorylation and its downstream target BCL-2 (p < 0.05), thereby inhibiting the proliferation of hRECs.
Conclusions :
Collectively, our findings suggest that LOX-PP suppresses the angiogenesis of hRECs upon high glucose exposure. This is the first report demonstrating the anti-angiogenic property of LOX-PP in hRECs. LOX-PP can be further investigated as a therapeutic molecule to inhibit retinal angiogenesis.
This is a 2020 ARVO Annual Meeting abstract.