Hyperglycemia-induced effects on glycocalyx components in the retina.

Autor: Kaur G; Louisiana State University Health Science Center-Shreveport, LA, Department of Molecular and Cellular Physiology, USA., Rogers J; Oklahoma State University, OK, Department of Biochemistry and Molecular Biology, USA., Rashdan NA; Louisiana State University Health Science Center-Shreveport, LA, Department of Molecular and Cellular Physiology, USA., Cruz-Topete D; Louisiana State University Health Science Center-Shreveport, LA, Department of Molecular and Cellular Physiology, USA., Pattillo CB; Louisiana State University Health Science Center-Shreveport, LA, Department of Molecular and Cellular Physiology, USA., Hartson SD; Oklahoma State University, OK, Department of Biochemistry and Molecular Biology, USA., Harris NR; Louisiana State University Health Science Center-Shreveport, LA, Department of Molecular and Cellular Physiology, USA. Electronic address: norman.harris@lsuhs.edu.
Jazyk: angličtina
Zdroj: Experimental eye research [Exp Eye Res] 2021 Dec; Vol. 213, pp. 108846. Date of Electronic Publication: 2021 Nov 18.
DOI: 10.1016/j.exer.2021.108846
Abstrakt: Purpose: Diabetic retinopathy is a vision-threatening complication of diabetes characterized by endothelial injury and vascular dysfunction. The loss of the endothelial glycocalyx, a dynamic layer lining all endothelial cells, contributes to several microvascular pathologies, including an increase in vascular permeability, leukocyte plugging, and capillary occlusion, and may drive the progression of retinopathy. Previously, a significant decrease in glycocalyx thickness has been observed in diabetic retinas. However, the effects of diabetes on specific components of the retinal glycocalyx have not yet been studied. Therefore, the aim of our study was to investigate changes in synthesis, expression, and shedding of retinal glycocalyx components induced by hyperglycemia, which could provide a novel therapeutic target for diabetic retinopathy.
Methods: Primary rat retinal microvascular endothelial cells (RRMECs) were grown under normal glucose (5 mM) or high-glucose (25 mM) conditions for 6 days. The mRNA and protein levels of the glycocalyx components were examined using qRT-PCR and Western blot analysis, respectively. Further, mass spectrometry was used to analyze protein intensities of core proteins. In addition, the streptozotocin-induced Type 1 diabetic rat model was used to study changes in the expression of the retinal glycocalyx in vivo. The shedding of the glycocalyx was studied in both culture medium and in plasma using Western blot analysis.
Results: A significant increase in the shedding of syndecan-1 and CD44 was observed both in vitro and in vivo under high-glucose conditions. The mRNA levels of syndecan-3 were significantly lower in the RRMECs grown under high glucose conditions, whereas those of syndecan-1, syndecan-2, syndecan-4, glypican-1, glypican-3, and CD44 were significantly higher. The protein expression of syndecan-3 and glypican-1 in RRMECs was reduced considerably following exposure to high glucose, whereas that of syndecan-1 and CD44 increased significantly. In addition, mass spectrometry data also suggests a significant increase in syndecan-4 and a significant decrease in glypican-3 protein levels with high glucose stimulation. In vivo, our data also suggest a significant decrease in the mRNA transcripts of syndecan-3 and an increase in mRNA levels of glypican-1 and CD44 in the retinas of diabetic rats. The diabetic rats exhibited a significant reduction in the retinal expression of syndecan-3 and CD44. However, the expression of syndecan-1 and glypican-1 increased significantly in the diabetic retina.
Conclusions: One of the main findings of our study was the considerable diversity of glucose-induced changes in expression and shedding of various components of endothelial glycocalyx, for example, increased endothelial and retinal syndecan-1, but decreased endothelial and retinal syndecan-3. This indicates that the reported decrease in the retinal glycocalyx in diabetes in not a result of a non-specific shedding mechanism. Moreover, mRNA measurements indicated a similar diversity, with increases in endothelial and/or retinal levels of syndecan-1, glypican-1, and CD44, but a decrease for syndecan-3, with these increases in mRNA potentially a compensatory reaction to the overall loss of glycocalyx.
(Copyright © 2021 Elsevier Ltd. All rights reserved.)
Databáze: MEDLINE
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