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Kaur G, Harris NR. Endothelial glycocalyx in retina, hyperglycemia, and diabetic retinopathy. Am J Physiol Cell Physiol 2023; 324:C1061-C1077. [PMID: 36939202 PMCID: PMC10125029 DOI: 10.1152/ajpcell.00188.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Revised: 02/28/2023] [Accepted: 03/16/2023] [Indexed: 03/21/2023]
Abstract
The endothelial glycocalyx (EG) is a meshlike network present on the apical surface of the endothelium. Membrane-bound proteoglycans, the major backbone molecules of the EG, consist of glycosaminoglycans attached to core proteins. In addition to maintaining the integrity of the endothelial barrier, the EG regulates inflammation and perfusion and acts as a mechanosensor. The loss of the EG can cause endothelial dysfunction and drive the progression of vascular diseases including diabetic retinopathy. Therefore, the EG presents a novel therapeutic target for treatment of vascular complications. In this review article, we provide an overview of the structure and function of the EG in the retina. Our particular focus is on hyperglycemia-induced perturbations in the glycocalyx structure in the retina, potential underlying mechanisms, and clinical trials studying protective treatments against degradation of the EG.
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Affiliation(s)
- Gaganpreet Kaur
- Department of Molecular and Cellular Physiology, Louisiana State University Health Sciences Center-Shreveport, Shreveport, Louisiana, United States
| | - Norman R Harris
- Department of Molecular and Cellular Physiology, Louisiana State University Health Sciences Center-Shreveport, Shreveport, Louisiana, United States
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Kaur G, Rogers J, Rashdan NA, Cruz-Topete D, Pattillo CB, Hartson SD, Harris NR. Hyperglycemia-induced effects on glycocalyx components in the retina. Exp Eye Res 2021; 213:108846. [PMID: 34801534 PMCID: PMC8665121 DOI: 10.1016/j.exer.2021.108846] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 11/10/2021] [Accepted: 11/12/2021] [Indexed: 11/19/2022]
Abstract
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.
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Affiliation(s)
- Gaganpreet Kaur
- Louisiana State University Health Science Center-Shreveport, LA, Department of Molecular and Cellular Physiology, USA
| | - Janet Rogers
- Oklahoma State University, OK, Department of Biochemistry and Molecular Biology, USA
| | - Nabil A Rashdan
- Louisiana State University Health Science Center-Shreveport, LA, Department of Molecular and Cellular Physiology, USA
| | - Diana Cruz-Topete
- Louisiana State University Health Science Center-Shreveport, LA, Department of Molecular and Cellular Physiology, USA
| | - Christopher B Pattillo
- Louisiana State University Health Science Center-Shreveport, LA, Department of Molecular and Cellular Physiology, USA
| | - Steven D Hartson
- Oklahoma State University, OK, Department of Biochemistry and Molecular Biology, USA
| | - Norman R Harris
- Louisiana State University Health Science Center-Shreveport, LA, Department of Molecular and Cellular Physiology, USA.
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Reine TM, Jenssen TG, Kolset SO. Glucosamine exposure reduces proteoglycan synthesis in primary human endothelial cells in vitro. Food Nutr Res 2016; 60:32615. [PMID: 27667774 PMCID: PMC5035772 DOI: 10.3402/fnr.v60.32615] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Revised: 08/17/2016] [Accepted: 08/19/2016] [Indexed: 01/09/2023] Open
Abstract
PURPOSE Glucosamine (GlcN) supplements are promoted for medical reasons, for example, for patients with arthritis and other joint-related diseases. Oral intake of GlcN is followed by uptake in the intestine, transport in the circulation and thereafter delivery to chondrocytes. Here, it is postulated to have an effect on synthesis and turnover of extracellular matrix constituents expressed by these cells. Following uptake in the intestine, serum levels are transiently increased, and the endothelium is exposed to increased levels of GlcN. We investigated the possible effects of GlcN on synthesis of proteoglycans (PGs), an important matrix component, in primary human endothelial cells. METHODS Primary human endothelial cells were cultured in vitro in medium with 5 mM glucose and 0-10 mM GlcN. PGs were recovered and analysed by western blotting, or by SDS-PAGE, gel chromatography or ion-exchange chromatography of (35)S-PGs after (35)S-sulphate labelling of the cells. RESULTS The synthesis and secretion of (35)S-PGs from cultured endothelial cells were reduced in a dose- and time-dependent manner after exposure to GlcN. PGs are substituted with sulphated glycosaminoglycan (GAG) chains, vital for PG function. The reduction in (35)S-PGs was not related to an effect on GAG chain length, number or sulphation, but rather to the total expression of PGs. CONCLUSION Exposure of endothelial cells to GlcN leads to a general decrease in (35)S-PG synthesis. These results suggest that exposure to high levels of GlcN can lead to decreased matrix synthesis, contrary to what has been claimed by supporters of such supplements.
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Affiliation(s)
- Trine M Reine
- Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
- Section of Nephrology, Department of Transplant Medicine, Oslo University Hospital, Rikshospitalet, Oslo, Norway;
| | - Trond Geir Jenssen
- Section of Nephrology, Department of Transplant Medicine, Oslo University Hospital, Rikshospitalet, Oslo, Norway
- Metabolic and Renal Research Group, Faculty of Health Sciences, UiT The Arctic University of Norway, Tromsø, Norway
| | - Svein Olav Kolset
- Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
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Reine TM, Vuong TT, Rutkovskiy A, Meen AJ, Vaage J, Jenssen TG, Kolset SO. Serglycin in Quiescent and Proliferating Primary Endothelial Cells. PLoS One 2015; 10:e0145584. [PMID: 26694746 PMCID: PMC4687888 DOI: 10.1371/journal.pone.0145584] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Accepted: 12/04/2015] [Indexed: 01/04/2023] Open
Abstract
Proteoglycans are fundamental components of the endothelial barrier, but the functions of the proteoglycan serglycin in endothelium are less described. Our aim was to describe the roles of serglycin in processes relevant for endothelial dysfunction. Primary human umbilical vein endothelial cells (HUVEC) were cultured in vitro and the expression of proteoglycans was investigated. Dense cell cultures representing the quiescent endothelium coating the vasculature was compared to sparse activated cell cultures, relevant for diabetes, cancer and cardiovascular disease. Secretion of 35S- proteoglycans increased in sparse cultures, and we showed that serglycin is a major component of the cell-density sensitive proteoglycan population. In contrast to the other proteoglycans, serglycin expression and secretion was higher in proliferating compared to quiescent HUVEC. RNAi silencing of serglycin inhibited proliferation and wound healing, and serglycin expression and secretion was augmented by hypoxia, mechanical strain and IL-1β induced inflammation. Notably, the secretion of the angiogenic chemokine CCL2 resulting from IL-1β activation, was increased in serglycin knockdown cells, while angiopoietin was not affected. Both serglycin and CCL2 were secreted predominantly to the apical side of polarized HUVEC, and serglycin and CCL2 co-localized both in perinuclear areas and in vesicles. These results suggest functions for serglycin in endothelial cells trough interactions with partner molecules, in biological processes with relevance for diabetic complications, cardiovascular disease and cancer development.
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Affiliation(s)
- Trine M Reine
- Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo, Box 1046, Blindern, 0316 Oslo, Norway.,Section of Renal Diseases, Department of Organ Transplantation, Oslo University Hospital-Rikshospitalet, Oslo, Norway
| | - Tram T Vuong
- Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo, Box 1046, Blindern, 0316 Oslo, Norway
| | - Arkady Rutkovskiy
- Department of Physiology, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.,Department of Emergency and Intensive Care, Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Astri J Meen
- Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo, Box 1046, Blindern, 0316 Oslo, Norway
| | - Jarle Vaage
- Department of Emergency and Intensive Care, Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Trond G Jenssen
- Section of Renal Diseases, Department of Organ Transplantation, Oslo University Hospital-Rikshospitalet, Oslo, Norway.,Metabolic and Renal Research Group, UiT The Arctic University of Norway, Tromsø, Norway
| | - Svein O Kolset
- Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo, Box 1046, Blindern, 0316 Oslo, Norway
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Marki A, Esko JD, Pries AR, Ley K. Role of the endothelial surface layer in neutrophil recruitment. J Leukoc Biol 2015; 98:503-15. [PMID: 25979432 DOI: 10.1189/jlb.3mr0115-011r] [Citation(s) in RCA: 92] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2015] [Accepted: 03/25/2015] [Indexed: 12/15/2022] Open
Abstract
Neutrophil recruitment in most tissues is limited to postcapillary venules, where E- and P-selectins are inducibly expressed by venular endothelial cells. These molecules support neutrophil rolling via binding of PSGL-1 and other ligands on neutrophils. Selectins extend ≤ 38 nm above the endothelial plasma membrane, and PSGL-1 extends to 50 nm above the neutrophil plasma membrane. However, endothelial cells are covered with an ESL composed of glycosaminoglycans that is ≥ 500 nm thick and has measurable resistance against compression. The neutrophil surface is also covered with a surface layer. These surface layers would be expected to completely shield adhesion molecules; thus, neutrophils should not be able to roll and adhere. However, in the cremaster muscle and in many other models investigated using intravital microscopy, neutrophils clearly roll, and their rolling is easily and quickly induced. This conundrum was thought to be resolved by the observation that the induction of selectins is accompanied by ESL shedding; however, ESL shedding only partially reduces the ESL thickness (to 200 nm) and thus is insufficient to expose adhesion molecules. In addition to its antiadhesive functions, the ESL also presents neutrophil arrest-inducing chemokines. ESL heparan sulfate can also bind L-selectin expressed by the neutrophils, which contributes to rolling and arrest. We conclude that ESL has both proadhesive and antiadhesive functions. However, most previous studies considered either only the proadhesive or only the antiadhesive effects of the ESL. An integrated model for the role of the ESL in neutrophil rolling, arrest, and transmigration is needed.
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Affiliation(s)
- Alex Marki
- *Division of Inflammation Biology, La Jolla Institute for Allergy and Immunology, La Jolla, California, USA; Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, California, USA; and Department of Physiology and Center for Cardiovascular Research, Charite, Berlin, Germany
| | - Jeffrey D Esko
- *Division of Inflammation Biology, La Jolla Institute for Allergy and Immunology, La Jolla, California, USA; Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, California, USA; and Department of Physiology and Center for Cardiovascular Research, Charite, Berlin, Germany
| | - Axel R Pries
- *Division of Inflammation Biology, La Jolla Institute for Allergy and Immunology, La Jolla, California, USA; Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, California, USA; and Department of Physiology and Center for Cardiovascular Research, Charite, Berlin, Germany
| | - Klaus Ley
- *Division of Inflammation Biology, La Jolla Institute for Allergy and Immunology, La Jolla, California, USA; Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, California, USA; and Department of Physiology and Center for Cardiovascular Research, Charite, Berlin, Germany
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Serglycin secretion is part of the inflammatory response in activated primary human endothelial cells in vitro. Biochim Biophys Acta Gen Subj 2014; 1840:2498-505. [PMID: 24513305 DOI: 10.1016/j.bbagen.2014.02.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Revised: 01/20/2014] [Accepted: 02/01/2014] [Indexed: 11/21/2022]
Abstract
BACKGROUND Endothelial cells have important functions in e.g. regulating blood pressure, coagulation and host defense reactions. Serglycin is highly expressed by endothelial cells, but there is limited data on the roles of this proteoglycan in immune reactions. METHODS Cultured primary human endothelial cells were exposed to proinflammatory agents lipopolysaccharide (LPS) and interleukin 1β (IL-1β). The response in serglycin synthesis, secretion and intracellular localization and effect on the proteoglycan binding chemokines CXCL-1 and CXCL-8 were determined by qRT-PCR, Western blotting, immunocytochemistry, ELISA and serglycin knockdown experiments. RESULTS Both LPS and IL-1β increased the synthesis and secretion of serglycin, while only IL-1β increased serglycin mRNA expression. Stimulation increased the number of serglycin containing vesicles, with a greater portion of large vesicles after LPS treatment. Also, increased intracellular and secreted levels of CXCL-1 and CXCL-8 were observed. The increase in CXCL-8 secretion was unchanged in serglycin knockdown cells. However, the increase in CXCL-1 secretion from IL-1β stimulation was reduced 27% in serglycin knockdown cells; while the LPS-induced secretion was not affected. In serglycin expressing cells CXCL-1 positive vesicles were evenly distributed throughout the cytoplasm, while confided to the Golgi region in serglycin knockdown cells. This was the case only for IL-1β stimulated cells. LPS-induced CXCL-1 distribution was unaffected by serglycin expression. CONCLUSIONS These results suggest that different signaling pathways are involved in regulating secretion of serglycin and partner molecules in activated endothelial cells. GENERAL SIGNIFICANCE This knowledge increases our understanding of the roles of serglycin in immune reactions. This article is part of a Special Issue entitled: Matrix-mediated cell behaviour and properties.
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Sasaki N, Toyoda M. Glycoconjugates and related molecules in human vascular endothelial cells. Int J Vasc Med 2013; 2013:963596. [PMID: 24171112 PMCID: PMC3793293 DOI: 10.1155/2013/963596] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Accepted: 08/12/2013] [Indexed: 11/18/2022] Open
Abstract
Vascular endothelial cells (ECs) form the inner lining of blood vessels. They are critically involved in many physiological functions, including control of vasomotor tone, blood cell trafficking, hemostatic balance, permeability, proliferation, survival, and immunity. It is considered that impairment of EC functions leads to the development of vascular diseases. The carbohydrate antigens carried by glycoconjugates (e.g., glycoproteins, glycosphingolipids, and proteoglycans) mainly present on the cell surface serve not only as marker molecules but also as functional molecules. Recent studies have revealed that the carbohydrate composition of the EC surface is critical for these cells to perform their physiological functions. In this paper, we consider the expression and functional roles of endogenous glycoconjugates and related molecules (galectins and glycan-degrading enzymes) in human ECs.
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Affiliation(s)
- Norihiko Sasaki
- Research Team for Geriatric Medicine (Vascular Medicine), Tokyo Metropolitan Institute of Gerontology, Sakaecho 35-2, Itabashi-ku, Tokyo 173-0015, Japan
| | - Masashi Toyoda
- Research Team for Geriatric Medicine (Vascular Medicine), Tokyo Metropolitan Institute of Gerontology, Sakaecho 35-2, Itabashi-ku, Tokyo 173-0015, Japan
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Heparan sulfate expression is affected by inflammatory stimuli in primary human endothelial cells. Glycoconj J 2011; 29:67-76. [PMID: 22187328 DOI: 10.1007/s10719-011-9365-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2011] [Revised: 12/05/2011] [Accepted: 12/08/2011] [Indexed: 12/13/2022]
Abstract
In diabetes the endothelium is either chronically or transiently exposed to hyperglycemic conditions. In addition, endothelial dysfunction in diabetes is related to changes in the inflammatory response and the turnover of extracellular matrix. This study was undertaken to study the effects of inflammatory stimuli on one particular matrix component, the heparan sulfate (HS) proteoglycans (PGs) synthesized by primary human umbilical cord vein endothelial cells (HUVEC). Such cells were cultured in vitro in 5 mM and 25 mM glucose. The latter concentration was used to mimic hyperglycemic conditions in short-term experiments. HUVEC were also cultured in the presence of the inflammatory agents tumor necrosis factor α (TNF-α), interleukin 1α (IL-1α), interleukin 1β (IL-1β) and transforming growth factor β (TGF-β). The cells were labeled with (35)S-sulfate and (35)S-PGs were recovered for further analyses. The major part of the (35)S-PGs was secreted to the medium, irrespective of type of stimuli. Secreted (35)S-PGs were therefore isolated and subjected to further analyses. TNF-α and IL-1α slightly increased the release of (35)S-PGs to the culture medium, whereas IL-1β treatment gave a significant increase. The different treatments neither changed the ratio of (35)S-HS and (35)S-chondroitin sulfate (CS) nor the macromolecular properties of the (35)S-PGs. However, the (35)S-HS chains were slightly increased in size after TNF-α treatment, and slightly decreased after TGF-β treatment, but not affected by the other treatments. Compositional analysis of labeled disaccharides showed changes in the amount of 6-O-sulfated glucosamine residues after treatment with TNF-α, IL-1α and IL-1β. Western immunoblotting showed that major HSPGs recovered from these cells were collagen XVIII, perlecan and agrin, and that secretion of these distinct PGs was increased after IL-1β stimulation. Hence, short term inflammatory stimuli increased the release of HSPGs in HUVEC and affected both the size and sulfation pattern of HS, depending on type of stimuli.
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Gharagozlian S, Svennevig K, Bangstad HJ, Winberg JO, Kolset SO. Matrix metalloproteinases in subjects with type 1 diabetes. BMC Clin Pathol 2009; 9:7. [PMID: 19758433 PMCID: PMC2753592 DOI: 10.1186/1472-6890-9-7] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2009] [Accepted: 09/16/2009] [Indexed: 11/19/2022] Open
Abstract
Background Nephropathy is serious complication of diabetes. We have previously shown that level of the proteoglycan syndecan-1 in blood is associated with ultrastructural kidney changes in young persons with type 1 diabetes. Dysregulation of matrix metalloproteinases (MMPs) and tissue inhibitors of matrix metalloproteinases (TIMPs) may contribute to the development of nephropathy. The aim of this study was to investigate if the levels of MMPs in blood samples are potential markers of early nephropathy in type 1 diabetes. Methods Blood samples were collected from type 1 diabetes patients after 11 years of diabetes (n = 15) and healthy volunteers (n = 12) and stored at ÷80°C until measurement. Levels and activities of serum MMP-2, MMP-9, TIMP-1 and TIMP- 2 were analyzed and compared to those of control individuals using ELISA, SDS-PAGE gelatin zymography, and Western blot analysis. Results The serum levels of both MMP-9 and MMP-2 were significantly higher in subjects with type 1 diabetes, compared to controls (p = 0.016 and p = 0.008 respectively). Western blotting revealed no differences between the two groups in the levels of TIMP-1 or TIMP-2, respectively. Conclusion Our MMP analysis of serum from a limited number of patients with type 1 diabetes suggest that such analysis is potentially useful as markers in studies of people at risk of progression to chronic kidney disease.
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Affiliation(s)
- Sedegheh Gharagozlian
- Department of Nutrition, Institute for Basic Medical Sciences, University of Oslo, Box 1046, Blindern, 0316 Oslo, Norway.
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Han J, Zhang F, Xie J, Linhardt RJ, Hiebert LM. Changes in cultured endothelial cell glycosaminoglycans under hyperglycemic conditions and the effect of insulin and heparin. Cardiovasc Diabetol 2009; 8:46. [PMID: 19695080 PMCID: PMC2739842 DOI: 10.1186/1475-2840-8-46] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2009] [Accepted: 08/20/2009] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND Heparan sulfate proteoglycans (HSPGs) contain glycosaminoglycan (GAG) chains made primarily of heparan sulfate (HS). Hyperglycemia in diabetes leads to endothelial injury and nephropathy, retinopathy and atherosclerosis. Decreased HSPG may contribute to diabetic endothelial injury. Decreased tissue HS in diabetes has been reported, however, endothelial HS changes are poorly studied. OBJECTIVE To determine total GAGs, including HS, in endothelium under hyperglycemic conditions and the protective effect of insulin and heparin. METHODS Confluent primary porcine aortic endothelial cells (PAECs) were divided into control, glucose (30 mM), insulin (0.01 unit/ml) and glucose plus insulin treatment groups for 24, 48 and 72 hours. Additionally, PAECs were treated with glucose, heparin (0.5 microg/ml) and glucose plus heparin for 72 hours. GAGs were isolated from cells and medium. GAG concentrations were determined by the carbazole assay and agarose gel electrophoresis. RESULTS GAGs were significantly increased only in control and glucose plus insulin groups at 72 versus 24 hours. Glucose decreased cell GAGs and increased medium GAGs, and insulin alone decreased cell GAGs at all times compared to control. In the glucose plus insulin group, cell GAGs were less than control at 24 hours, and greater than glucose or insulin alone at 48 and 72 hours while GAGs in medium were greater than control at all times and glucose at 72 hours. Heparin increased GAGs in glucose treated cells and medium. CONCLUSION High glucose and insulin alone reduces endothelial GAGs. In hyperglycemic conditions, heparin or insulin preserves GAGs which may protect cells from injury. Insulin is an effective diabetic therapy since it not only lowers blood glucose, but also protects endothelium.
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Affiliation(s)
- Juying Han
- Department of Veterinary Biomedical Sciences, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5B4, Canada.
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Potter DR, Jiang J, Damiano ER. The recovery time course of the endothelial cell glycocalyx in vivo and its implications in vitro. Circ Res 2009; 104:1318-25. [PMID: 19443840 DOI: 10.1161/circresaha.108.191585] [Citation(s) in RCA: 114] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Compelling evidence continues to emerge suggesting that the glycocalyx surface layer on vascular endothelial cells plays a determining role in numerous physiological processes including inflammation, microvascular permeability, and endothelial mechanotransduction. Previous research has shown that enzymes degrade the glycocalyx, whereas inflammation causes shedding of the layer. To track the endogenous recovery of the glycocalyx in vivo, we used fluorescent microparticle image velocimetry (micro-PIV) in mouse cremaster muscle venules to estimate the hydrodynamically relevant glycocalyx thickness 1, 3, 5, and 7 days after enzymatic or cytokine-mediated degradation of the layer. Results indicate that after acute degradation of the glycocalyx, 5 to 7 days are required for the layer to endogenously restore itself to its native hydrodynamically relevant thickness in vivo. In light of these findings, and because demonstrable evidence has emerged that standard cell culture conditions are not conducive to providing the environment and/or cellular conditions necessary to produce and maintain a physiologically relevant cell surface glycocalyx in vitro, we sought to determine whether merely the passage of time would be sufficient to promote the production of a hydrodynamically relevant glycocalyx on a confluent monolayer of human umbilical vein endothelial cells (HUVECs). Using micro-PIV, we found that the hydrodynamically relevant glycocalyx was substantially absent 7 days postconfluence on HUVEC-lined cylindrical collagen microchannels maintained under standard culture conditions. Thus, it remains to be determined how a hydrodynamically relevant glycocalyx surface layer can be synthesized and maintained in culture before the endothelial cell culture model can be used to elucidate glycocalyx-mediated mechanisms of endothelial cell function.
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Affiliation(s)
- Daniel R Potter
- Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA
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Asplund A, Östergren-Lundén G, Camejo G, Stillemark-Billton P, Bondjers G. Hypoxia increases macrophage motility, possibly by decreasing the heparan sulfate proteoglycan biosynthesis. J Leukoc Biol 2009; 86:381-8. [DOI: 10.1189/jlb.0908536] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
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Götting C, Kuhn J, Kleesiek K. Serum xylosyltransferase activity in diabetic patients as a possible marker of reduced proteoglycan biosynthesis. Diabetes Care 2008; 31:2018-9. [PMID: 18650370 PMCID: PMC2551647 DOI: 10.2337/dc08-0909] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2008] [Accepted: 07/16/2008] [Indexed: 02/03/2023]
Abstract
OBJECTIVE Proteoglycan metabolism is altered in diabetic patients. The xylosyltransferases (XTs) are the initial and rate-limiting enzymes in the biosynthesis of the glycosaminoglycan chains in proteoglycans. Here, we analyzed whether the changed proteoglycan metabolism leads to altered serum XT levels in diabetic patients. RESEARCH DESIGN AND METHODS Serum XT activity was determined in 100 diabetic patients and 100 blood donors using a novel high-performance liquid chromatography electrospray ionization tandem mass spectrometry assay. RESULTS Serum XT activities in male and female diabetic patients were significantly decreased compared with those in the corresponding normoglycemic control subjects (mean +/- SD: male patients, 19.3 +/- 4.44 mU/l; male nondiabetic control subjects, 26.6 +/- 2.79 mU/l; female patients, 18.9 +/- 3.14 mU/l; female nondiabetic control subjects, 21.8 +/- 3.74 mU/l; P < 0.0001). No significant differences were detected between patients with type 1 and type 2 diabetes. CONCLUSIONS Our data show decreased XT activity in patients with diabetes, a disease that is accompanied by an altered proteoglycan biosynthesis.
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Affiliation(s)
- Christian Götting
- Institut für Laboratoriums-und Transfusionsmedizin, Herz-und Diabeteszentrum Nordrhein-Westfalen, Universitätsklinik der Ruhr-Universität Bochum, Bad Oeynhausen, Germany.
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