Author:

Keywords:

Science & Technology, Life Sciences & Biomedicine, Ophthalmology, diabetic retinopathy, blood-retinal barrier, platelet factor-4 variant (PF-4var/CXCL4L1), ENDOTHELIAL GROWTH-FACTOR, GLYCATION END-PRODUCTS, MACULAR EDEMA, IN-VIVO, ANGIOGENESIS, CELLS, RETINOPATHY, VEGF, PLATELETS, RECEPTOR, platelet factor-4 variant (PF-4var CXCL4L1), Animals, Biomarkers, Blood-Retinal Barrier, Caspase 3, Cells, Cultured, Diabetes Mellitus, Experimental, Diabetic Retinopathy, Endothelial Cells, Epiretinal Membrane, Humans, Male, Platelet Factor 4, Rats, Reactive Oxygen Species, Vascular Endothelial Growth Factor A, 06 Biological Sciences, 11 Medical and Health Sciences, Ophthalmology & Optometry, 3212 Ophthalmology and optometry

Abstract:

Purpose:To investigate the expression of platelet factor-4 variant (PF-4var) in epiretinal membranes from patients with proliferative diabetic retinopathy (PDR) and the role of PF-4var in the regulation of blood-retinal barrier (BRB) breakdown in diabetic rat retinas and human retinal microvascular endothelial cells (HRMEC). Methods:Rats were treated intravitreally with PF-4var or the anti-vascular endothelial growth factor (VEGF) agent bevacizumab on the first day after diabetes induction. BRB breakdown was assessed in vivo with fluorescein isothiocyanate (FITC)-conjugated dextran and in vitro in HRMEC by transendothelial electrical resistance and FITC-conjugated dextran cell permeability assay. Occludin, vascular endothelial (VE)-cadherin, hypoxia-inducible factor (HIF)-1α, VEGF, tumor necrosis factor (TNF)-α, receptor for advanced glycation end products (RAGE), caspase-3 levels and generation of reactive oxygen species (ROS) were assessed by Western blot, enzyme-linked immunosorbent assays or spectrophotometry. Results:In epiretinal membranes, vascular endothelial cells and stromal cells expressed PF-4var. In vitro, HRMEC produced PF-4var after stimulation with a combination of interleukin (IL)-1β and TNF-α and PF-4var inhibited VEGF-mediated hyperpermeability in HRMEC. In rats PF-4var was as potent as bevacizumab in attenuating diabetes-induced BRB breakdown. This effect was associated with upregulation of occludin and VE-cadherin and downregulation of HIF-1α, VEGF, TNF-α, RAGE and caspase-3, whereas ROS generation was not altered. Conclusions:Our findings suggest that increasing intraocular PF-4var levels early after the onset of diabetes protects against diabetes-induced BRB breakdown.