The lectin-like domain of tumor necrosis factor-α increases membrane conductance in microvascular endothelial cells and peritoneal macrophages

Hribar, Marusa; Bloc, Alain; Goot, F. Gisou van der; Fransen, Lucie; Baetseĺier, Patrick De; Grau, Georges E.; Bluethmann, Horst; Matthay, Michael A.; Dunant, Yves; Pugin, Jérôme; Lucas, Rudolf

doi:10.1002/(sici)1521-4141(199910)29:10<3105::aid-immu3105>3.3.co;2-1

Cited by 10 publications

(10 citation statements)

References 20 publications

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“…At a molar ratio of 30:1 to TNF, Etanercept only weakly inhibited E-selectin expression, whereas full neutralization occurred with infliximab (46). Our observation that the preincubation of TNF with N,NЈ-diacetylchitobiose is able to block TNF-mediated Na ϩ transport (20) as well as TNF-mediated activation of edema reabsorption indicates that TNF is binding directly to sugar groups of a still unknown receptor on alveolar epithelial cells. We are currently investigating this possibility.…”

Section: Figurementioning

confidence: 73%

“…This structural element recognizes specific oligosaccharides, such as N,NЈ-diacetylchitobiose and branched trimannoses (17,18). This domain of TNF, moreover, mediates the trypanolytic activity of the cytokine (19) and activates amiloride-sensitive sodium transport in mammalian cells (20). The functions of the lectin-like domain of TNF can be mimicked by a synthetic circular peptide that contains 17 aa (Tip peptide (Tip)).…”

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confidence: 99%

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Dichotomal Role of TNF in Experimental Pulmonary Edema Reabsorption

Braun

Hamacher

Morel³

et al. 2005

The Journal of Immunology

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109

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Distinct from its receptor binding sites, TNF carries a lectin-like domain, situated at the tip of the molecule, which specifically binds oligosaccharides, such as N,N′-diacetylchitobiose. In view of the apparently conflicting data concerning TNF actions in pulmonary edema, we investigated the contribution of, on the one hand, the receptor binding sites and, in contrast, the lectin-like domain of the cytokine on pulmonary fluid reabsorption in in situ and in vivo flooded rat lungs. Receptor binding sites were blocked with the human soluble TNFR type 1 construct (sTNFR1), whereas the lectin-like domain was blunted with the oligosaccharide N,N′-diacetylchitobiose. We observed that in situ, TNF failed to stimulate alveolar liquid clearance, but did so together with the sTNFR1, and this activity was neutralized by N,N′-diacetylchitobiose. In vivo TNF inhibited liquid clearance, but activated it when complexed with the sTNFR1. A TNF-derived peptide mimic of the lectin-like domain activated fluid reabsorption in flooded lungs, and this activity was blunted by cotreatment with TNF. Our results thus indicate that in these models the receptor binding sites of TNF inhibit, whereas its lectin-like domain activates, edema reabsorption.

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Section: Figurementioning

confidence: 73%

mentioning

confidence: 99%

Dichotomal Role of TNF in Experimental Pulmonary Edema Reabsorption

Braun

Hamacher

Morel³

et al. 2005

The Journal of Immunology

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109

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“…We demonstrate that PKC-a inhibitors are able to blunt PLY-mediated arginase activation in vitro and can prevent PLY-induced pulmonary endothelial hyperpermeability in mice in vivo. We also observed a potent protective effect of the TNFderived tonoplast intrinsic protein (TIP) peptide (21)(22)(23)(24), which was shown to activate amiloride-sensitive sodium transport in alveolar epithelial and microvascular endothelial cells (24,25), the latter of which express the a subunit of the epithelial sodium channel ENaC (26,27). The TIP peptide was previously shown to protect from hyperpermeability induced by the cholesterol-binding pore-forming toxin listeriolysin in human lung microvascular endothelial cell (HL-MVEC) monolayers in an amiloride-sensitive and PKC-a-dependent manner (28).…”

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confidence: 89%

Protein Kinase C-α and Arginase I Mediate Pneumolysin-Induced Pulmonary Endothelial Hyperpermeability

Lucas

Yang

Gorshkov

et al. 2012

Am J Respir Cell Mol Biol

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Antibiotics-induced release of the pore-forming virulence factor pneumolysin (PLY) in patients with pneumococcal pneumonia results in its presence days after lungs are sterile and is a major factor responsible for the induction of permeability edema. Here we sought to identify major mechanisms mediating PLY-induced endothelial dysfunction. We evaluated PLY-induced endothelial hyperpermeability in human lung microvascular endothelial cells (HL-MVECs) and human lung pulmonary artery endothelial cells in vitro and in mice instilled intratracheally with PLY. PLY increases permeability in endothelial monolayers by reducing stable and dynamic microtubule content and modulating VE-cadherin expression. These events, dependent upon an increased calcium influx, are preceded by protein kinase C (PKC)-a activation, perturbation of the RhoA/Rac1 balance, and an increase in myosin light chain phosphorylation. At later time points, PLY treatment increases the expression and activity of arginase in HL-MVECs. Arginase inhibition abrogates and suppresses PLY-induced endothelial barrier dysfunction by restoring NO generation. Consequently, a specific PKC-a inhibitor and the TNF-derived tonoplast intrinsic protein peptide, which blunts PLY-induced PKC-a activation, are able to prevent activation of arginase in HL-MVECs and to reduce PLY-induced endothelial hyperpermeability in mice. Arginase I (AI) 1/2 /arginase II (AII) 2/2 C57BL/6 mice, displaying a significantly reduced arginase I expression in the lungs, are significantly less sensitive to PLY-induced capillary leak than their wild-type or AI 1/1 /AII 2/2 counterparts, indicating an important role for arginase I in PLYinduced endothelial hyperpermeability. These results identify PKC-a and arginase I as potential upstream and downstream therapeutic targets in PLY-induced pulmonary endothelial dysfunction.Keywords: PKC; arginase; pneumococcus; pneumolysin; TNF Although severe pneumonia remains the leading cause of mortality worldwide in children aged less than 5 years (1), community-acquired pneumonia represents a major cause of morbidity and mortality mainly in elderly patients (2). Despite the use of potent antibiotics and aggressive intensive care support, the fatality rate associated with Streptococcus pneumoniae, accounting for 45% of all cases of community-acquired pneumonia, is approximately 20% (1, 2). Pulmonary permeability edema, a major complication of severe pneumonia characterized by endothelial hyperpermeability, can occur days after initiation of antibiotics therapy when tissues are sterile and the pneumonia is clearing and correlates with the presence of the bacterial virulence factor pneumolysin (PLY) (3, 4). This cytoplasmic hemolytic protein is released during bacterial lysis, as occurs after treatment with b-lactam antibiotics (5). PLYinduced lung injury was suggested to result from direct pneumotoxic effects on the alveolar-capillary barrier rather than from resident or recruited phagocytic cells (6).Upon binding of PLY to cholesterol in cell membranes, oligo...

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“…In contrast to large vessels, the presence or role of ENaC in the microvasculature, such as in the capillaries in the lung, remains understudied and represents the primary focus of this study. The TIP peptide was shown to increase Na + uptake in pulmonary microvascular endothelial cells (26) and to restore impaired endothelial barrier function in the presence of the pore-forming toxins PLY and listeriolysin-O (3, 27). …”

Section: Introductionmentioning

confidence: 99%

Epithelial Sodium Channel-α Mediates the Protective Effect of the TNF-Derived TIP Peptide in Pneumolysin-Induced Endothelial Barrier Dysfunction

et al. 2017

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BackgroundStreptococcus pneumoniae is a major etiologic agent of bacterial pneumonia. Autolysis and antibiotic-mediated lysis of pneumococci induce release of the pore-forming toxin, pneumolysin (PLY), their major virulence factor, which is a prominent cause of acute lung injury. PLY inhibits alveolar liquid clearance and severely compromises alveolar–capillary barrier function, leading to permeability edema associated with pneumonia. As a consequence, alveolar flooding occurs, which can precipitate lethal hypoxemia by impairing gas exchange. The α subunit of the epithelial sodium channel (ENaC) is crucial for promoting Na+ reabsorption across Na+-transporting epithelia. However, it is not known if human lung microvascular endothelial cells (HL-MVEC) also express ENaC-α and whether this subunit is involved in the regulation of their barrier function.MethodsThe presence of α, β, and γ subunits of ENaC and protein phosphorylation status in HL-MVEC were assessed in western blotting. The role of ENaC-α in monolayer resistance of HL-MVEC was examined by depletion of this subunit by specific siRNA and by employing the TNF-derived TIP peptide, a specific activator that directly binds to ENaC-α.ResultsHL-MVEC express all three subunits of ENaC, as well as acid-sensing ion channel 1a (ASIC1a), which has the capacity to form hybrid non-selective cation channels with ENaC-α. Both TIP peptide, which specifically binds to ENaC-α, and the specific ASIC1a activator MitTx significantly strengthened barrier function in PLY-treated HL-MVEC. ENaC-α depletion significantly increased sensitivity to PLY-induced hyperpermeability and in addition, blunted the protective effect of both the TIP peptide and MitTx, indicating an important role for ENaC-α and for hybrid NSC channels in barrier function of HL-MVEC. TIP peptide blunted PLY-induced phosphorylation of both calmodulin-dependent kinase II (CaMKII) and of its substrate, the actin-binding protein filamin A (FLN-A), requiring the expression of both ENaC-α and ASIC1a. Since non-phosphorylated FLN-A promotes ENaC channel open probability and blunts stress fiber formation, modulation of this activity represents an attractive target for the protective actions of ENaC-α in both barrier function and liquid clearance.ConclusionOur results in cultured endothelial cells demonstrate a previously unrecognized role for ENaC-α in strengthening capillary barrier function that may apply to the human lung. Strategies aiming to activate endothelial NSC channels that contain ENaC-α should be further investigated as a novel approach to improve barrier function in the capillary endothelium during pneumonia.

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The lectin-like domain of tumor necrosis factor-α increases membrane conductance in microvascular endothelial cells and peritoneal macrophages

Cited by 10 publications

References 20 publications

Dichotomal Role of TNF in Experimental Pulmonary Edema Reabsorption

Dichotomal Role of TNF in Experimental Pulmonary Edema Reabsorption

Protein Kinase C-α and Arginase I Mediate Pneumolysin-Induced Pulmonary Endothelial Hyperpermeability

Epithelial Sodium Channel-α Mediates the Protective Effect of the TNF-Derived TIP Peptide in Pneumolysin-Induced Endothelial Barrier Dysfunction

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