Showing papers on "Neutrophil extracellular traps published in 1994"

Neutrophil apoptosis is associated with a reduction in CD16 (Fc gamma RIII) expression.

Abstract: Resolution of inflammation involves removal of recruited neutrophils from inflamed sites via a noninflammatory mechanism, possibly involving neutrophil apoptosis and engulfment/phagocytosis by macrophages. In this study, we describe the reduction in surface expression (> 90%) of the neutrophil molecule Fc gamma RIII (CD16) during in vitro culture at 37 degrees C, which was found to be temporally associated with the appearance of neutrophils with apoptotic morphology during in vitro culture and inhibitable by granulocyte-macrophage colony-stimulating factor (GM-CSF), which postpones apoptosis in the neutrophil. By using dual fluorescence analysis, CD16 "low" expressing neutrophils showed reduced staining with the DNA-binding dye propidium iodide, suggesting that CD16 low expressing neutrophils were apoptotic. Separation of CD16 "high" and CD16 "low" expressing neutrophils by fluorescence-activated cell sorting revealed that morphologically apoptotic cells exhibited the CD16 low phenotype. We did not observe similar marked changes in expression of other neutrophil surface molecules (including other phosphatidylinositol (PI)-linked molecules), indicating that generalized loss of surface molecules does not occur during apoptosis. We believe this to be the first reported cell type-specific membrane alteration in a surface glycoprotein associated with apoptosis, suggesting that the program of cell death in the neutrophil, in addition to morphologic and nuclear changes, includes alterations in expression of surface receptors.

Neutrophils roll on adherent neutrophils bound to cytokine-induced endothelial cells via L-selectin on the rolling cells.

Abstract: Specific arrest of neutrophils in venules is central to their rapid accumulation during local inflammatory responses. Initial neutrophil rolling on endothelium is mediated by leukocyte L-selectin and the inducible vascular adhesion proteins P- and E-selectin. This rolling is a prerequisite for endothelial-dependent neutrophil arrest. Here we describe rolling of neutrophils on the surface of previously arrested neutrophils and demonstrate that this interaction involves L-selectin exclusively on rolling cells. The adherent neutrophil support of L-selectin-dependent neutrophil rolling in vivo can promote continuous and augmented leukocyte recruitment at sites of previous neutrophil accumulation.

The role of neutrophil elastase in chronic inflammation.

Abstract: Passively released or actively secreted elastase from neutrophils has been linked to the pathologic processes of a variety of inflammatory diseases, including idiopathic pulmonary fibrosis, rheumatoid arthritis, adult respiratory distress syndrome, and cystic fibrosis. The serine proteinase has a broad substrate specificity and may attack a number of host proteins outside of the neutrophil, including lung elastin and fibronectin. Such a proteolysis may change the normal surrounding tissue and the protein pattern of an inflammatory focus. Additionally, it acts as a potent secretagogue in minute amounts. The reason that neutrophil elastase is present in considerable concentrations outside of the neutrophil during chronic inflammation and that the major endogenous serine proteinase inhibitor for neutrophil elastase, alpha 1-proteinase inhibitor, is easily inactivated by proteolytic and oxidative attack is unclear. Released neutrophil elastase may also be involved in regulating chronic inflammation. In a feedback mechanism, neutrophil elastase inhibits neutrophil stimulation and concomitant elastase release by cleavage of immunoglobulins, complement components, and complement receptor type 1 on neutrophils. Besides a number of harmful effects of neutrophil elastase in inflammation, the latter mechanism, although considerably impairing phagocytosis, may be beneficial particularly in the light of persistent bacterial pathogens in the human lung affected by cystic fibrosis.

Immunopharmacology of neutrophils

Abstract: The Neutrophil, P.G. Hellewell and T.J. Williams. Origin and Development of Neutrophils, M.Y. Gordon. The Respiratory Burst of Neutrophils and its Deficiency, C. Casimir and C.G. Teahan. Neutrophil Proteases: Their Physiological and Pathological Roles, N. Doherty and M. Janusz. Neutrophis-Derived Inflammatory Mediators, H. Showell and S. McColl. Molecular Biology of Human Neutrophil Chemotactic Receptors, C. Gerard and N. Gerard. Adhesion Receptors on Neutrophils, A.J. Wardlaw and G.M. Walsh. Receptor-Mediated Signal Transduction Pathways in Neutrophils: Regulatory Mechanisms that Control Phospholipases C, D and A2, S. Cockcroft. Priming of Neutrophils, M.J. Pabst. Mechanisms of Neutrophil Accumulation in Tissues, A.G. Rossi and P.G. Hellewell. Role of Neutrophils in Reperfusion Injury, F.M. Williams. Role of Neutrophils in Vasculitis, A. Rees and C. Savage. Role of Neutrophils in Adult Respiratory Distress Syndrome and Interstitial Pulmonary Fibrosis, S. Braude, T.W. Evans, and R.M. du Bois. Fate of Neutrophils, J. Savill and C. Haslett.

IL-8 secretion and neutrophil activation by HT-29 colonic epithelial cells

Abstract: This study examines the ability of HT-29 human colonic epithelial cells to stimulate neutrophil migration and adhesion. Interleukin-8 (IL-8), a potent neutrophil chemoattractant, was detected in conditioned media from both unstimulated (1.1 ng/ml) and IL-1 beta-stimulated (16.1 ng/ml) HT-29 cultures. Conditioned medium from IL-1 beta-exposed HT-29 cells stimulated neutrophil migration (395% of control, P < 0.01), and this effect was completely inhibited by anti-IL-8 antibody. HT-29 medium also induced shedding of neutrophil L-selectin and increased expression of neutrophil CD11/CD18 adhesion receptors. Coculture of HT-29 cells with human endothelial cell monolayers resulted in increased neutrophil transendothelial migration (169% of control, P < 0.01), which was blocked by both anti-IL-8 and anti-CD18 antibody. Northern hybridization analysis demonstrated increased levels of mRNA for IL-8 and intercellular adhesion molecule-1 (ICAM-1) in cytokine-treated HT-29 cells. Cytokine stimulation of HT-29 monolayers was also associated with increased neutrophil adhesion to these cells. Neutrophil-HT-29 cell adhesion was blocked by monoclonal antibodies to neutrophil CD18 or to ICAM-1 on the HT-29 cells (86% and 56% inhibition, respectively, P < 0.01 for both). These data suggest that IL-8 secretion by activated colonic epithelial cells may contribute to neutrophil extravasation and tissue infiltration in intestinal inflammation.

Regulation of ICAM‐3 (CD50) membrane expression on human neutrophils through a proteolytic shedding mechanism

Abstract: The regulation of the cell surface expression of ICAM-3 (CD50) was investigated in human neutrophils. Immunofluorescence flow cytometry analysis revealed a remarkable and very rapid down-regulation of the ICAM-3 cell surface expression upon neutrophil activation with stimulating agents such as phorbol myristate acetate (PMA) or calcium ionophore. A similar low expression of ICAM-3 was observed on neutrophils from patients undergoing hemodialysis with cell-activating cellulosic membranes. Internalization assays with 125I-labeled anti-ICAM-3 monoclonal antibody (mAb) suggested that ICAM-3-down-regulation was due to antigen release from the cell surface towards the outer milieu, rather than to antigen internalization. Immunoprecipitation studies confirmed this down-regulatory effect, and revealed the presence of ICAM-3 in cell-free supernatants from activated neutrophils. Furthermore, the presence of a soluble form of ICAM-3 with a range of concentrations of 0-296 ng/ml in the plasma from healthy human volunteers was detected by using a two-site mAb radioimmunoassay. A proteolytic mechanism likely accounts for this process since protease inhibitors virtually abrogated the PMA-induced down-regulation of ICAM-3. Functional studies showed that anti-ICAM-3 mAb were able to trigger homotypic neutrophil aggregation both before and after ICAM-3 down-regulation, indicating that the fraction of ICAM-3 molecules remaining on the neutrophil surface upon activation are still capable of sustaining cell adhesion. In contrast, the loss of L-selectin (CD62L) on activated neutrophils was almost complete, thus leading to an impairment of L-selectin-mediated neutrophil-endothelial cell adhesion. These results indicate that ICAM-3 is released to the medium upon neutrophil stimulation and that both ICAM-3 and L-selectin have a role in the neutrophil adhesive phenomena.

Neutrophil lysosomal dysfunctions in mutant C57 Bl/6J mice: interstrain variations in content of lysosomal elastase, cathepsin G and their inhibitors.

Abstract: In this paper we report the serum antiprotease screening and the biochemical and functional characteristics of neutrophils in a variety of mouse strains with different susceptibilities for developing a protease-mediated injury. C57Bl/6J mice and their mutants tight-skin and pallid have a lower serum elastase inhibitory capacity (-30, -65 and -70% respectively) than other inbred strains (i.e. NMRI and Balb/c, which both have similar values). We demonstrate that these values are a consequence of a decreased concentration of the alpha 1-protease inhibitor for elastase [PI(E)], which is the major serum inhibitor of elastase and cathepsin G. In addition, neutrophil lysosomal dysfunctions characterized by abnormally high contents of elastase and cathepsin G, or defective lysosomal secretion are observed in tight-skin and pallid mice respectively. Another C57Bl/6J mutant with lysosomal abnormalities is the beige mouse. Negligible amounts of elastase and cathepsin G, as well as defective neutrophil degranulation, have been described previously in this strain. We found, however, discrete amounts of a latent form of neutrophil elastase that undergoes a spontaneous activation by a protease-dependent mechanism. We also report that neutrophil cathepsin G in this mouse is tightly bound to lysosomal membranes, but is released in near normal quantities during exocytosis. Cytosolic elastase and cathepsin G inhibitors, which were previously reported as being specific for the beige neutrophils, have also been detected in all the examined strains. Neutrophil functions, lysosomal enzyme content and serum antiprotease screening may represent key elements in the protease-antiprotease balance and may explain the different interstrain susceptibility to developing lesions in which an elastolytic activity has been implicated.

Identification of possible inhibitory reactive centers in thrombospondin 1 that may bind cathepsin G and neutrophil elastase.

Abstract: Thrombospondin 1 is a multidomain trimeric glycoprotein from platelets and a variety of normal and transformed cells of both mesenchymal and epithelial origin, which functions in cell adhesion and cell-cell interactions. We have recently shown that human thrombospondin 1 binds and inhibits the neutrophil enzymes, neutrophil elastase [Hogg, P.J., Owensby, D.A., Mosher, D.F., Misenheimer, T.M., & Chesterman, C.N. (1993a) J. Biol. Chem. 268, 7139-7146] and cathepsin G [Hogg, P.J., Owensby, D.A., & Chesterman, C.N. (1993b) J. Biol. Chem. 268, 21811-21818]. One mole of thrombospondin 1 trimer binds 3 mol of neutrophil elastase or up to 6 mol of cathepsin G, with site-binding dissociation constants around the nanomolar range, and the enzymes have been shown to interact with thrombospondin 1 in the vicinity of the calcium-binding type 3 repeats. None of the protein modules in this region, or within the whole thrombospondin 1 molecule, have previously been implicated in the inhibition of proteinases. We noted that there are two stretches of eight amino acids each in the human thrombospondin 1 type 3 repeats, residues 735-742 and 794-801, that have striking similarity to a reactive-site consensus sequence derived from selected members of the Kazal and Streptomyces subtilisin inhibitor families. Synthetic peptides corresponding to the putative P5 through P4' residues of both proposed reactive centers interacted efficiently with the active site of cathepsin G and were competitive inhibitors of the fibronectin-degrading and platelet-activating activities of this enzyme, while only the peptide corresponding to residues 793-801 efficiently interacted with the active site of neutrophil elastase and competitively inhibited its fibronectin-degrading activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Inhibitory effect of prostaglandin E1 on human neutrophil function

Abstract: Neutrophils accumulated in the lung are thought to play a pivotal role in the pathogenesis of host auto-injury such as adult respiratory distress syndrome (ARDS). We investigated the effect of prostaglandin E1 (PGE1) on several aspects of human neutrophil function. PGE1 significantly decreased reactive oxygen species (ROS), (O2−, H2O2, OH·) generation by neutrophils as well as neutrophil phagocytosis and chemotaxis. In contrast, the drug did not affect the levels of ROS generated by a cell-free ROS generating system. In addition, intracellular calcium concentrations ([Ca2+]i) in neutrophils stimulated by f-Met-Leu-Phe were decreased in the presence of PGE1. These data suggest that the reduction in ROS production and neutrophil phagocytosis and chemotaxis by PGE1 may contribute to the effectiveness of the drug in host auto-injury including ARDS. The suppression of the increase in [Ca2+]i may at least be responsible for inhibition of these neutrophil functions by PGE1.

The Local Role of Tumor Necrosis Factor α in the Modulation of Neutrophil Function at Sites of Inflammation

Abstract: Objective: To examine the hypothesis that tumor necrosis factor α (TNF-α) is an important local modulator of neutrophil function in the inflammatory microenvironment. Design: In vitro studies of host defense. Patients: A volunteer sample of healthy subjects. Intervention: Exudative neutrophils were collected from skin-blister chambers and functionally compared with blood neutrophils. Methods: Tumor necrosis factor α levels at sites of inflammation and neutrophil exudation were determined and compared with serum concentrations. Flow cytometry was used to evaluate neutrophil microbicidal activity and N -formyl-methionyl-leucyl-phenylalanine—induced changes in intracellular calcium and superoxide production. In vitro TNF-α was used to evaluate the nature and dose response of TNF-α–induced changes in neutrophil function. Results: Exudative neutrophils have an increased responsiveness to subsequent N -formyl-methionyl-leucyl-phenylalanine stimulation, as determined by changes in intracellular calcium. Microbicidal activity and superoxide production are also up-regulated compared with circulating neutrophils. The exudative microenvironment contains TNF-α at local levels that are capable of significantly enhancing neutrophil host defense. Conclusions: Tumor necrosis factor α may serve to enhance neutrophil function at sites of inflammation. Neutrophils become more cytotoxic and have an enhanced ability to respond to weak environmental signals. (Arch Surg. 1994;129:1249-1255)

In vitro and in vivo impact of a new glycosphingolipid on neutrophils

Abstract: A new water-soluble, orally absorbable de-N-acetyl-lysoganglioside (WILD20), breakdown product of the monosialoganglioside GM1, was found to influence some parameters of neutrophil response to inflammation stimuli. Superoxide anion production appears inhibited, along with neutrophil killing properties. A block of both pathways of arachidonic acid cascade and PAF was also found, as well as neutrophil ICAM-1-mediated adhesion to endothelial cells. Of particular interest was the significant reduction of neutrophils observed at the site of inflammation, whichever agonist was used. The effects on neutrophil physiology found in normal or in pathological conditions, are in favour of a WILD20-related inhibitory effect on neutrophil contribution to inflammation.

Role of calcium in neutrophil activation by Japanese encephalitis virus-induced macrophage derived factor.

Abstract: The role of cytosolic Ca2+ concentration in neutrophils stimulated with macrophage derived neutrophil chemotactic factor (MDF) produced following Japanese encephalitis virus (JEV) infection in mice was correlated with cell functions. MDF-induced Ca2+ influx from extracellular milieu and release from intracellular store resulted in rise of cytosolic Ca2+ in a dose-dependent manner and was independent of protein kinase C. Macrophages and B cells did not show cytosolic Ca2+ changes while T lymphocytes showed slight rise when stimulated with MDF. Neutrophil chemotaxis in the absence of Ca2+ was slightly different from that in presence of Ca2+. Pretreatment of neutrophils with 3,4,5-trimethoxy-benzoic acid-8-(diethylamine)-octylester (TMB-8) inhibited the chemotaxis. It was observed that superoxide production and degranulation by neutrophils after stimulation with MDF was not dependent on the presence of extracellular calcium, but stripping of intracellular calcium resulted in abrogation of neutrophil activation. Thus, mobilization of intracellular calcium seems to be necessary for neutrophil activation by MDF.