scholarly journals Heparanase-2 protects from LPS-mediated endothelial injury by inhibiting TLR4 signalling

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Yulia Kiyan ◽  
Sergey Tkachuk ◽  
Kestutis Kurselis ◽  
Nelli Shushakova ◽  
Klaus Stahl ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Heparan Sulfate ◽  
Cell Activation ◽  
Cell Signalling ◽  
Plasma Concentrations ◽  
Endothelial Damage ◽  
Endothelial Glycocalyx ◽  
Endothelial Cell Activation

Abstract The endothelial glycocalyx and its regulated shedding are important to vascular health. Endo-β-D-glucuronidase heparanase-1 (HPSE1) is the only enzyme that can shed heparan sulfate. However, the mechanisms are not well understood. We show that HPSE1 activity aggravated Toll-like receptor 4 (TLR4)-mediated response of endothelial cells to LPS. On the contrary, overexpression of its endogenous inhibitor, heparanase-2 (HPSE2) was protective. The microfluidic chip flow model confirmed that HPSE2 prevented heparan sulfate shedding by HPSE1. Furthermore, heparan sulfate did not interfere with cluster of differentiation-14 (CD14)-dependent LPS binding, but instead reduced the presentation of the LPS to TLR4. HPSE2 reduced LPS-mediated TLR4 activation, subsequent cell signalling, and cytokine expression. HPSE2-overexpressing endothelial cells remained protected against LPS-mediated loss of cell-cell contacts. In vivo, expression of HPSE2 in plasma and kidney medullary capillaries was decreased in mouse sepsis model. We next applied purified HPSE2 in mice and observed decreases in TNFα and IL-6 plasma concentrations after intravenous LPS injections. Our data demonstrate the important role of heparan sulfate and the glycocalyx in endothelial cell activation and suggest a protective role of HPSE2 in microvascular inflammation. HPSE2 offers new options for protection against HPSE1-mediated endothelial damage and preventing microvascular disease.

scholarly journals Heparanase-2 protects from endothelial injury by inhibiting TLR4 signaling

2019 ◽  
Author(s):  
Yulia Kiyan ◽  
Sergey Tkachuk ◽  
Kestutis Kurselis ◽  
Nelli Shushakova ◽  
Klaus Stahl ◽  
...  
Keyword(s):  
Cell Culture ◽  
Endothelial Cells ◽  
Heparan Sulfate ◽  
Microfluidic Chip ◽  
Cell Activation ◽  
Plasma Concentrations ◽  
Endothelial Glycocalyx ◽  
Endothelial Cell Activation

AbstractObjectiveThe endothelial glycocalyx and the regulation of its shedding are important to vascular health. Endo-β-D-glucuronidase heparanase-1 (HPSE1) is the only enzyme that can shed heparan sulfate. However, the mechanisms are not well understood.Approach and resultsTo investigate HPSE1 and its endogenous inhibitor, heparanase-2 (HPSE2), we used cell culture, lentiviral protein overexpression, a microfluidic chip model of cell culture under shear stress conditions, and lipopolysaccharide (LPS) injections in mice. We show that HPSE1 activity aggravated Toll-like receptor 4 (TLR4)-mediated response of endothelial cells to LPS. On the contrary, HPSE2 overexpression was protective. The microfluidic chip flow model confirmed that HPSE2 prevented heparan sulfate shedding by HPSE1. Furthermore, heparan sulfate did not interfere with cluster of differentiation-14 (CD14)-dependent LPS binding, but instead reduced the presentation of the LPS-CD14 complex to TLR4. HPSE2 reduced LPS-mediated TLR4 activation by LPS, subsequent cell signaling, and cytokine expression. Moreover, HPSE2-overexpressing endothelial cells remained protected against LPS-mediated loss of cell-cell contacts. In vivo, expression of HPSE2 in plasma and kidney medullary capillaries was decreased in mouse sepsis model. We next applied purified HPSE2 in mice and observed decreases in TNFα and IL-6 plasma concentrations after intravenous LPS injections.ConclusionsOur data demonstrate the important role of heparan sulfate and the glycocalyx in endothelial cell activation and suggest a protective role of HPSE2 in microvascular inflammation. HPSE2 offers new options for protection against HPSE1-mediated endothelial damage and preventing microvascular disease. Graphical abstractNon standard abbreviations

Abstract MP27: Human Hypertension And Endothelial Cell Activation Promote The Formation And Activation Of Axl + Siglec-6 + Dendritic Cells Via Endothelial Release Of Growth Arrest Specific 6

Hypertension ◽  
2020 ◽  
Vol 76 (Suppl_1) ◽  
Author(s):  
Justin P Van Beusecum ◽  
Natalia R Barbaro ◽  
Charles D Smart ◽  
David M Patrick ◽  
Cyndya A Shibao ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Endothelial Cells ◽  
Dendritic Cells ◽  
Endothelial Cell ◽  
Cell Activation ◽  
Growth Arrest ◽  
Positive Association ◽  
Endothelial Cell Activation ◽  
Human Hypertension

We have shown that dendritic cells (DCs) from hypertensive mice convey hypertension when adoptively transferred to recipients. Recently a novel subset of DCs in humans that express Axl and Sigelc-6 + (AS DCs) have been identified which drive T cell proliferation and produce IL-1β, IL-6 and IL-23, consistent with DCs we have observed in hypertension. We hypothesized that AS cells are increased in hypertension and contribute to immune activation in this disease. We quantified circulating AS DCs by flow cytometry in normotensive (n=23) and hypertensive (n=11) subjects and found a more than 2-fold increase in circulating AS DCs in hypertensive compared to normotensive subjects (297 ± 73 vs. 108 ± 26/ml; p =0.0304). To investigate the mechanism by which AS DCs are formed in hypertension, we co-cultured human aortic endothelial cells (HAECs) undergoing either normotensive (5%) or hypertensive (10%) cyclical stretch for 48 hours with CD14 + monocytes from normotensive donors. Co-culture of monocytes with HAECs exposed to 10% stretch significantly increased AS DCs and AS DC IL-1β production when compared to 5% stretch alone as assessed by flow cytometry (21 ± 5 vs. 131 ± 32 IL-1β + AS DCs). Moreover, inhibition of Axl signaling with R248, completely abolished the production of IL-1β in AS DCs (34 ± 8 IL-1β + AS DCs). In additional experiments we found that 10% stretch caused a 50% increase in release of growth arrest 6 (GAS6), the ligand for Axl, from HAECs compared to 5% stretch. Treatment of human monocytes with GAS6 mimicked the effect of 10% stretch in promoting AS cell formation and IL-1β production. Based on the increased secretion of GAS6 from HAECs, we used a J-wire to harvest human endothelial cells from 23 additional volunteers to assess endothelial cell activation and GAS6 secretion in vivo. We found a positive association between pulse pressure and plasma GAS6 (R 2 =0.25, p =0.0079) and a striking positive association between GAS6 and ICAM-1 (R 2 =0.39, p =0.0012). These data show that secretion of GAS6 by an activated endothelial seems to promote the formation and activation of AS DCs. Thus, the interplay between endothelial-derived GAS6 and AS DCs seem to be an important mechanism in human hypertension and might be a novel therapeutic target for this disease.

160. THE ROLE OF PHAGOCYTOSIS OF APOPTOTIC SYNCYTIAL KNOTS IN THE PREVENTION OF ENDOTHELIAL CELL ACTIVATION: AN IMPORTANT ADAPTATION FOR NORMAL PREGNANCY

2010 ◽  
Vol 22 (9) ◽  
pp. 78
Author(s):  
Q. Chen ◽  
H. Jin ◽  
P. Stone ◽  
L. Chamley
Keyword(s):  
Endothelial Cells ◽  
Endothelial Cell ◽  
Immune Responses ◽  
Cell Activation ◽  
Normal Pregnancy ◽  
Cytochalasin D ◽  
Endothelial Cell Activation ◽  
Endothelial Cell Surface ◽  
Large Numbers

Preeclampsia is characterised by an exaggerated inflammatory response and maternal endothelial cell activation. Syncytial knots, dead multinucleated fetal cells shed from the placenta in large numbers during all pregnancies, may be phagocytosed by maternal endothelial cells. Our previous studies showed that phagocytosis of necrotic but not apoptotic syncytial knots led to endothelial cell activation. It is known that phagocytosis of apoptotic cells leads to active tolerance of immune responses and in this study we questioned whether phagocytosis of apoptotic syncytial knots leads to suppression of the endothelial cells ability to be activated. Syncytial knots were harvested from 1st trimester placental explants. Monolayers of endothelial cells were pre-treated with apoptotic syncytial knots for 24 h. After washing, the endothelial cells were treated with the endothelial cell activators LPS, PMA, IL-6, or necrotic syncytial knots for 24 h. In some experiments the inhibitor of phagocytosis, cytochalasin D, was added into the cultures along with apoptotic syncytial knots. Endothelial cell-surface ICAM-1 was measured using cell based ELISAs. Expression of ICAM-1 by endothelial cells that had phagocytosed apoptotic syncytial knots prior to treatment with LPS, PMA, IL-6, or necrotic syncytial knots was significantly (P =/<0.003) reduced, compared to control endothelial cells that had not phagocytosed apoptotic syncytial knots. Inhibiting phagocytosis of apoptotic syncytial knots with cytochalasin D abolished this protective effect. Our data suggest phagocytosis of apoptotic syncytial knots results in the suppression of the ability of endothelial cells to be activated by a number of potent chemical activators, as well as by the physiologically relevant activator, necrotic syncytial knots. This work suggests that the release of apoptotic syncytial knots from the placenta during normal pregnancy may be a mechanism by which the fetus attempts to protect the maternal vasculature against activation.

scholarly journals Enhancing Antitumor Efficacy of Heavily Vascularized Tumors by RAMBO Virus through Decreased Tumor Endothelial Cell Activation

Cancers ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 1040
Author(s):  
Mitra Nair ◽  
Maninder Khosla ◽  
Yoshihiro Otani ◽  
Margaret Yeh ◽  
Flora Park ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Endothelial Cell ◽  
Solid Tumors ◽  
Cell Activation ◽  
Leukocyte Adhesion ◽  
Oncolytic Viruses ◽  
Endothelial Cell Activation ◽  
Microscopy Imaging ◽  
Activation Markers

Vascularization is a common pathology for many solid tumors, and therefore anti-angiogenic strategies are being investigated as a therapeutic target for treatment. Numerous studies are also being conducted regarding the effects of oncolytic viruses, including ImlygicTM, an FDA approved oncolytic herpes simplex virus-1 (oHSV) for the treatment of highly vascularized tumors such as Kaposi sarcoma (NCT04065152), and brain tumors. To our knowledge, the effects of combining oncolytic HSV with angiogenesis inhibition on endothelial cell activation has not been previously described. Here, we tested the effects of Rapid Antiangiogenesis Mediated By Oncolytic Virus (RAMBO), an oHSV which expresses a potent anti-angiogenic gene Vasculostatin on endothelial cell activation in heavily vascularized solid tumors. oHSV treatment induces endothelial cell activation, which inhibits virus propagation and oncolysis in adjacent tumor cells in vitro. Consistently, this was also observed in intravital imaging of intracranial tumor-bearing mice in vivo where infected tumor endothelial cells could efficiently clear the virus without cell lysis. Quantitative real-time PCR (Q-PCR), leukocyte adhesion assay, and fluorescent microscopy imaging data, however, revealed that RAMBO virus significantly decreased expression of endothelial cell activation markers and leukocyte adhesion, which in turn increased virus replication and cytotoxicity in endothelial cells. In vivo RAMBO treatment of subcutaneously implanted sarcoma tumors significantly reduced tumor growth in mice bearing sarcoma compared to rHSVQ. In addition, histological analysis of RAMBO-treated tumor tissues revealed large areas of necrosis and a statistically significant reduction in microvessel density (MVD). This study provides strong preclinical evidence of the therapeutic benefit for the use of RAMBO virus as a treatment option for highly vascularized tumors.

Toll like Receptor 4 Is Involved in In VIvo Antiphospholipid-Mediated Thrombosis and Endothelial Cell Activation.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 133-133
Author(s):  
Silvia S. Pierangeli ◽  
Mariano E. Vega-Ostertag ◽  
Elena Raschi ◽  
Xiaowei Liu ◽  
Maria O. Borghi ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Endothelial Cell ◽  
Antiphospholipid Syndrome ◽  
Cell Activation ◽  
Spontaneous Mutation ◽  
Toll Like Receptor ◽  
Endothelial Cell Activation ◽  
Toll Like Receptor 4 ◽  
Control Serum

Abstract Background: Antiphospholipid antibodies (aPL) are associated with thrombosis and pregnancy loss in patients with Antiphospholipid Syndrome (APS). aPL and bacterial lipopolysaccharide (LPS) bind to and activate endothelial cells (EC) through NFκB and p38 MAPK pathways. Recent studies suggest that aPL might interact with toll-like receptor-4 (TLR-4), the receptor for LPS. Aim: to investigate the role of TLR-4 in antiphospholipid syndrome (APS). Methods: we examined: i) the aPL effects on thrombosis and EC activation in LPS non-responsive (LPS−/−) mice that display a spontaneous mutation of TLR-4 vs LPS-responsive (LPS+/+) mice displaying wild type TLR-4, ii) the prevalence of TLR-4 Asp299gly and Thr399Ile polymorphisms - both associated with decreased response to LPS - in 110 APS patients (with arterial and/or venous thrombosis) vs 220 controls (of same ethnic background). IgGs were purified from a patient with APS (IgG-APS) and from control serum (IgG-NHS). LPS −/− and LPS +/+ mice, in groups of nine, were treated with IgG-APS or with IgG-NHS twice intraperitoneally. Size of induced thrombi and # of leukocyte (WBC) adhering to endothelial cells in the microcirculation of endothelium of the cremaster muscle of mice (as a means to measure endothelial cell activation) were determined in vivo, seventy-two hours after the first injection. TLR-4 Asp299gly & Thr399Ile polymorphisms were evaluated by Allele-Specific PCR. Results: LPS +/+ mice treated with IgG-APS produced significantly larger thrombi when compared to mice treated with IgG-NHS (2166 ± 1419 μm2 vs 1176 ± 841 μm2) and significantly larger number of WBC adherence to ECs (4.5 ± 1.9 vs 2.2 ±1.1). Thrombus size and number of adhering WBC to ECs were significantly lower in LPS −/− mice treated with IgG-APS compared to LPS +/+ mice treated with IgG-APS [thrombus size: 779 ± 628 μm2 vs 2166 ± 1419 μm2 (p&lt;0.05) and number of adherent WBC to EC: 1.0 ± 0.5 vs 4.5 1.9 (p&lt;0.05)], respectively. The titer of anticardiolipin antibodies in the sera of mice injected with aPL was 48.2 ± 17.1 GPL (for LPS −/− mice) and 50.8 ± 11.2 GPL (for LPS +/+ mice), respectively (NS). A significant reduction in TLR-4 Asp 299gly & Thr399Ile polymorphisms was observed in APS patients (5%) compared to controls (11.4%) (p&lt;0.05). Conclusions: These findings strongly suggest that TLR-4 is involved in aPL interaction with endothelial cells and mediates their pathogenic effects.

Monitoring Endothelial Cell Activation In Vivo during Thrombus Formation.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 294-294
Author(s):  
Ben T. Atkinson ◽  
Prathima Nandivada ◽  
Bruce Furie ◽  
Barbara C. Furie
Keyword(s):  
Endothelial Cells ◽  
Endothelial Cell ◽  
Intracellular Calcium ◽  
Cell Activation ◽  
Thrombus Formation ◽  
Single Cells ◽  
Calcium Mobilization ◽  
Endothelial Cell Activation ◽  
Calcium Elevation

Abstract The endothelium serves as a metabolically active interface between the blood and underlying tissues and offers response to changes in its microenvironment. The endothelium is rapidly activated in response to stimuli associated with fluctuations in shear stress, physical trauma, oxidative stress, and thrombotic and inflammatory mediators. To study endothelial cell activation we have monitored calcium mobilization in vitro in cultured endothelial cells and also in situ in the living mouse, following vessel wall injury. The addition of exogenous ADP (10 μM) or thrombin (1 U/mL) to Human Umbilical Vein Endothelial Cells (HUVECs) loaded with the calcium sensitive dye, Fluo-4 AM, is followed by rapid elevation of intracellular calcium, with a sustained peak observed within 10 sec. To further investigate the ability of the endothelium to activate in response to mediators potentially localized in the microenvironment of the endothelium during thrombus formation, we investigated the ability of IL-6 (0.1 ng/mL), IL-8 (80 ng/mL), MCP-1 (15 ng/mL), NAP-2 (10 ng/mL) and SDF-α (60 ng/mL) to mobilize calcium in HUVECs. These potential agonists were selected based on their primary roles in inflammation and thrombosis, and proposed roles in atherosclerosis and tumor angiogenesis. SDF-α and NAP-2 rapidly mobilized calcium in HUVECs, with similar maximum responses, but NAP-2 initiated a more prolonged (4-fold longer) rise in intracellular calcium. IL-6, IL-8, and MCP-1 also mobilized calcium, but the rise in intracellular calcium was almost 4-fold lower than that observed with SDF-α and NAP-2. Comparable calcium mobilization occurs in HUVECs subjected to a single pulse of a nitrogen dye-tuned laser. In addition, targeting of single cells within a confluent culture of endothelial cells initiated calcium elevation in the targeted cell and was followed by a wave of calcium elevation in surrounding cells. To determine whether this endothelial cell activation, and more specifically the calcium elevation, occurs in vivo, we conducted experiments using the laser-induced model of thrombus formation to look for calcium elevation in the arteriolar endothelium in live mice. Calcium elevation was monitored by Fluo-4AM introduced intravenously into the mouse circulation via the jugular vein. Fluo-4AM is non-specific in its uptake among cell types, and endothelial cell uptake of the dye in the cremaster muscle microcirculation was observed. Upon laser-induced injury, calcium elevation in the endothelium could be monitored by intravital microscopy. The observed calcium elevation was rapid (within 30 s) and preceded detection of platelets in the developing thrombus. These results add to the evidence of a dynamic endothelium and demonstrate that the endothelium activates rapidly prior to thrombus formation in the laser induced thrombosis model.

Gas6 Regulates Thrombin-Induced of VCAM-1 Expression by a FoxO1 Dependent Mechanism

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 5192-5192
Author(s):  
Richard Robins ◽  
Catherine A. Lemarie ◽  
Mark D. Blostein
Keyword(s):  
Endothelial Cells ◽  
Endothelial Cell ◽  
Venous Thrombosis ◽  
Cell Biology ◽  
Cell Activation ◽  
Conflicts Of Interest ◽  
Vascular Dysfunction ◽  
Soluble Form ◽  
Endothelial Cell Activation

Abstract Abstract 5192 Forkhead proteins play a broad role in endothelial cell biology. These factors mediate cell adhesion to extracellular matrix, regulate the expression of pro-inflammatory and pro-thrombotic genes, and participate in cell repair, proliferation and apoptosis. FoxOs are known downstream targets of the PI3K/Akt signaling pathway. Phosphorylation of FoxO transcription factors results in their translocation from the nucleus to the cytoplasm, thereby inhibiting their transcriptional activity. It has recently been shown that the deletion of the three FoxO isoforms in endothelial cells protects mice from vascular dysfunction. Gas6, a member of the vitamin K-dependent family of proteins, has been shown to protect endothelial cells from apoptosis and promote endothelial cell activation in vivo. It has been shown that the expression of ICAM-1 and VCAM-1 were blunted in the absence of gas6. Interestingly, a role for VCAM-1 in the pathogenesis of venous thrombosis has been proposed. Elevated levels of the soluble form of VCAM-1 have been detected in the serum of patients with venous thrombosis. We previously demonstrated that the anti-apoptotic effect of gas6 was mediated partially through FoxO1, but overall, the signalling mechanisms occurring downstream of gas6 remain largely unknown. We hypothesize that gas6 promotes thrombin-induced VCAM-1 expression through the regulation of FoxO1 in endothelial cells. Western blot analysis demonstrated that thrombin induced time dependent phosphorylation of FoxO1 with a maximum at 30 minutes in WT (p<0. 05) but not in gas6 deficient (−/−) cells. In addition, thrombin reduced the nuclear content of FoxO in WT (p<0. 05) but not in gas6−/− endothelial cells. Using qPCR, we found that mRNA expression of VCAM-1 was increased after 30 minutes of stimulation with thrombin in WT cells (p<0. 05). More importantly, thrombin-mediated induction of VCAM-1 was blunted in gas6−/− endothelial cells. We found that FoxO1 siRNA increased basal VCAM-1 expression in WT endothelial cells. Taken together, our data demonstrate that gas6 is a crucial mediator of FoxO1 that regulates thrombin-induced VCAM-1 expression. This pathway may explain the pro-thrombotic and pro-inflammatory role of gas6. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Nintedanib Reduces Neutrophil Chemotaxis via Activating GRK2 in Bleomycin-Induced Pulmonary Fibrosis

2020 ◽  
Vol 21 (13) ◽  
pp. 4735 ◽  
Author(s):  
Wei-Chih Chen ◽  
Nien-Jung Chen ◽  
Hsin-Pai Chen ◽  
Wen-Kuang Yu ◽  
Vincent Yi-Fong Su ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Pulmonary Fibrosis ◽  
Mouse Model ◽  
Cell Activation ◽  
Neutrophil Chemotaxis ◽  
Endothelial Cell Activation ◽  
Late Antigen ◽  
Blood Neutrophils ◽  
Cell Adhesion Molecule 1

Neutrophils are involved in the alveolitis of idiopathic pulmonary fibrosis (IPF). However, their pathogenic mechanisms are still poorly understood. Nintedanib has antifibrotic and anti-inflammatory activity in IPF. This study aimed to investigate the regulatory mechanism of nintedanib on neutrophil chemotaxis in bleomycin (BLM)-induced pulmonary fibrosis. Nintedanib was administered via oral gavage to male C57BL/6 mice 24 h after a bleomycin intratracheal injection (1.5 U/kg). Lung histopathological findings, the expression of cytokines, and the regulatory signaling pathways of neutrophil chemotaxis were analyzed. The effect of nintedanib was also investigated in a mouse model with adoptive neutrophil transfer in vivo. Nintedanib significantly decreased the histopathological changes and neutrophil recruitment in BLM-induced pulmonary fibrosis. Nintedanib mediated a downregulation of chemokine (C-X-C motif) receptor 2 (CXCR2) and very late antigen 4 (VLA-4) expression, as well as an upregulation of G protein-coupled receptor kinase 2 (GRK2) activity in peripheral blood neutrophils in BLM-induced pulmonary fibrosis. Nintedanib also decreased the activation of endothelial cells by the decreased expression of vascular cell adhesion molecule 1 (VCAM-1). The effect of nintedanib on regulating neutrophil chemotaxis was also confirmed by a mouse model with adoptive neutrophil transfer in vivo. In conclusion, nintedanib reduces neutrophil chemotaxis and endothelial cell activation to regulate the severity of BLM-induced pulmonary fibrosis. These effects are associated with an enhancement of GRK2 activity and a reduction in CXCR2 and VLA-4 expression on neutrophils and a decrease in VCAM-1 expression on endothelial cells.

Differential expression and regulation of murine CD40 in regional vascular beds

2006 ◽  
Vol 290 (2) ◽  
pp. H631-H639 ◽  
Author(s):  
Thorsten Vowinkel ◽  
Katherine C. Wood ◽  
Karen Y. Stokes ◽  
Janice Russell ◽  
Christian F. Krieglstein ◽  
...  
Keyword(s):  
Cell Activation ◽  
Constitutive Expression ◽  
Vascular Endothelial ◽  
Endothelial Cell Activation ◽  
Signaling Mechanism ◽  
Antibody Technique ◽  
Cd40 Expression ◽  
Vascular Beds

There is emerging evidence for a role of the CD40/CD40 ligand (CD40L) dyad as a signaling mechanism in different inflammatory conditions. The aims of this study were to 1) quantify the constitutive and induced expression of CD40 in different regional vascular beds of the mouse and 2) assess the role of CD40L as a modulator of vascular endothelial CD40 expression. The dual radiolabeled monoclonal antibody technique was used to quantify the expression of endothelial CD40 in control and LPS-challenged wild-type (WT) mice. Significant constitutive CD40 expression was detected in several vascular beds of WT mice with lung, kidney, and small intestine exhibiting the highest expression, whereas the liver and stomach showed no detectable baseline expression. LPS administration elicited two- to sevenfold increases in CD40 expression in several tissues (heart, kidney, and intestine) within 4 h, whereas other organs (brain) required up to 48 h to exhibit CD40 upregulation. CD40 expression was not detected in unstimulated or LPS-challenged CD40−/− mice. Constitutive expression of CD40 was profoundly reduced in unstimulated CD40L−/− mice, but the LPS-induced CD40 upregulation did not differ between CD40L−/− and WT mice. Depletion of platelets or T lymphocytes, the major CD40L-expressing cells in blood, also resulted in a profound reduction in basal CD40 expression. These findings demonstrate significant endothelial expression of CD40 under basal conditions in different vascular beds and increased CD40 expression after endothelial cell activation with LPS. Platelet- and T-lymphocyte-associated CD40L appears to play a major role in regulating the density of CD40 expression on vascular endothelial cells in vivo.

Endothelial Heparan Sulfate Proteoglycans in Sepsis: The Role of the Glycocalyx

2021 ◽  
Vol 47 (03) ◽  
pp. 274-282
Author(s):  
Kaori Oshima ◽  
Samantha I. King ◽  
Sarah A. McMurtry ◽  
Eric P. Schmidt
Keyword(s):  
Heparan Sulfate ◽  
Vascular Function ◽  
Platelet Adhesion ◽  
Vascular Dysfunction ◽  
Heparan Sulfate Proteoglycans ◽  
Endothelial Glycocalyx ◽  
Endothelial Surface ◽  
Mechanistic Investigation

AbstractThere is increasing recognition of the importance of the endothelial glycocalyx and its in vivo manifestation, the endothelial surface layer, in vascular homeostasis. Heparan sulfate proteoglycans (HSPGs) are a major structural constituent of the endothelial glycocalyx and serve to regulate vascular permeability, microcirculatory tone, leukocyte and platelet adhesion, and hemostasis. During sepsis, endothelial HSPGs are shed through the induction of “sheddases” such as heparanase and matrix metalloproteinases, leading to loss of glycocalyx integrity and consequent vascular dysfunction. Less well recognized is that glycocalyx degradation releases HSPG fragments into the circulation, which can shape the systemic consequences of sepsis. In this review, we will discuss (1) the normal, homeostatic functions of HSPGs within the endothelial glycocalyx, (2) the pathological changes in HSPGs during sepsis and their consequences on the local vascular bed, and (3) the systemic consequences of HSPG degradation. In doing so, we will identify potential therapeutic targets to improve vascular function during sepsis as well as highlight key areas of uncertainty that require further mechanistic investigation.

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