The Experts below are selected from a list of 1314 Experts worldwide ranked by ideXlab platform
Asrar B Malik - One of the best experts on this subject based on the ideXlab platform.
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β2 integrin blockade driven by e selectin promoter prevents Neutrophil sequestration and lung injury in mice
Circulation Research, 2000Co-Authors: Arshad Rahman, Richard D Minshall, Chinnaswamy Tiruppathi, Asrar B MalikAbstract:Interaction of CD11/CD18 beta(2) integrins on polymorphonuclear leukocytes (PMNs) with their counterreceptor, intercellular adhesion molecule-1, on the surface of vascular endothelial cells is a critical event mediating stable PMN adhesion and migration across the pulmonary vascular endothelial barrier. Neutrophil Inhibitory Factor (NIF), a 41-kDa glycoprotein isolated from the canine hookworm (Ancylostoma caninum), binds to the I domain of CD11a and CD11b and inhibits beta(2) integrin-dependent PMN adhesion. We describe a novel strategy using the endothelial cell-specific E-selectin promoter to induce NIF expression in an inflammation-specific manner in pulmonary vascular endothelial cells. A construct containing NIF cDNA driven by the inducible endothelial cell-specific E-selectin promoter (pESNIF) was transfected into human pulmonary artery endothelial cells (HPAECs). Lipopolysaccharide challenge (known to activate E-selectin) resulted in NIF mRNA and protein expression in transfected HPAECs. NIF expression induced by the E-selectin promoter prevented PMN adhesion to the activated HPAECs, whereas PMNs adhered avidly to activated HPAECs in the absence of NIF expression. To address the utility of this approach in conditionally preventing in vivo PMN sequestration, we injected mice intravenously with cationic liposomes containing the pESNIF construct. Analysis of lung tissue showed that intraperitoneal challenge of Escherichia coli resulted in NIF expression. Inflammation-specific NIF expression induced by the E-selectin promoter prevented lung PMN sequestration and vascular injury induced by E coli challenge. These studies suggest the feasibility of conditionally blocking beta(2) integrin function at sites where the endothelium is activated and thereby of locally preventing PMN activation and migration responses that lead to tissue inflammation.
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Neutrophil Inhibitory Factor abrogates Neutrophil adhesion by blockade of cd11a and cd11b β2 integrins
Molecular Pharmacology, 1999Co-Authors: Arshad Rahman, Ming Yuan Zhou, Pablito G Nagpala, Howard A Jaffe, Asrar B MalikAbstract:We studied the basis of inhibition of polymorphonuclear leukocyte (PMN) adhesion induced by Neutrophil Inhibitory Factor (NIF), a 41-kDa CD11/CD18 beta(2) integrin-binding protein isolated from the canine hookworm (Ancylostoma caninum). NIF blocked PMN adhesion in a concentration-dependent manner with complete blockade occurring at approximately 10 nM NIF. Because CD11a and CD11b beta(2) integrins are functionally active on stimulated PMNs, and yet NIF is postulated to inhibit only CD11b integrin by binding to its I domain, we evaluated the contributions of CD11a and CD11b beta(2) integrins in the mechanism of inhibition of PMN adhesion to endothelial cells. We observed an additive Inhibitory effect (>90% inhibition) of PMN adhesion to endothelial cells when NIF was used in combination with anti-CD11b monoclonal antibodies, which alone at saturating concentrations reduced PMN adhesion by only 50%. NIF also prevented aggregation of phorbol ester-stimulated JY lymphoblastoid cells that expressed only the functionally active CD11a, suggesting that NIF also can inhibit CD11a-dependent response. We transduced the NIF cDNA into human dermal microvessel endothelial cells in which NIF synthesis and release prevented PMN adhesion to the transduced human dermal microvessel endothelial cells. These data indicated that the potent antiadhesive effect of NIF may be the result of inhibition of CD11a and CD11b beta(2) integrins on PMNs. Moreover, the strategy of NIF release from transduced endothelial cells suggests the feasibility of blocking the CD11a- and CD11b beta(2) integrin-dependent PMN adhesion and PMN migration responses specifically at sites of endothelial cell activation.
Arshad Rahman - One of the best experts on this subject based on the ideXlab platform.
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β2 integrin blockade driven by e selectin promoter prevents Neutrophil sequestration and lung injury in mice
Circulation Research, 2000Co-Authors: Arshad Rahman, Richard D Minshall, Chinnaswamy Tiruppathi, Asrar B MalikAbstract:Interaction of CD11/CD18 beta(2) integrins on polymorphonuclear leukocytes (PMNs) with their counterreceptor, intercellular adhesion molecule-1, on the surface of vascular endothelial cells is a critical event mediating stable PMN adhesion and migration across the pulmonary vascular endothelial barrier. Neutrophil Inhibitory Factor (NIF), a 41-kDa glycoprotein isolated from the canine hookworm (Ancylostoma caninum), binds to the I domain of CD11a and CD11b and inhibits beta(2) integrin-dependent PMN adhesion. We describe a novel strategy using the endothelial cell-specific E-selectin promoter to induce NIF expression in an inflammation-specific manner in pulmonary vascular endothelial cells. A construct containing NIF cDNA driven by the inducible endothelial cell-specific E-selectin promoter (pESNIF) was transfected into human pulmonary artery endothelial cells (HPAECs). Lipopolysaccharide challenge (known to activate E-selectin) resulted in NIF mRNA and protein expression in transfected HPAECs. NIF expression induced by the E-selectin promoter prevented PMN adhesion to the activated HPAECs, whereas PMNs adhered avidly to activated HPAECs in the absence of NIF expression. To address the utility of this approach in conditionally preventing in vivo PMN sequestration, we injected mice intravenously with cationic liposomes containing the pESNIF construct. Analysis of lung tissue showed that intraperitoneal challenge of Escherichia coli resulted in NIF expression. Inflammation-specific NIF expression induced by the E-selectin promoter prevented lung PMN sequestration and vascular injury induced by E coli challenge. These studies suggest the feasibility of conditionally blocking beta(2) integrin function at sites where the endothelium is activated and thereby of locally preventing PMN activation and migration responses that lead to tissue inflammation.
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Neutrophil Inhibitory Factor abrogates Neutrophil adhesion by blockade of cd11a and cd11b β2 integrins
Molecular Pharmacology, 1999Co-Authors: Arshad Rahman, Ming Yuan Zhou, Pablito G Nagpala, Howard A Jaffe, Asrar B MalikAbstract:We studied the basis of inhibition of polymorphonuclear leukocyte (PMN) adhesion induced by Neutrophil Inhibitory Factor (NIF), a 41-kDa CD11/CD18 beta(2) integrin-binding protein isolated from the canine hookworm (Ancylostoma caninum). NIF blocked PMN adhesion in a concentration-dependent manner with complete blockade occurring at approximately 10 nM NIF. Because CD11a and CD11b beta(2) integrins are functionally active on stimulated PMNs, and yet NIF is postulated to inhibit only CD11b integrin by binding to its I domain, we evaluated the contributions of CD11a and CD11b beta(2) integrins in the mechanism of inhibition of PMN adhesion to endothelial cells. We observed an additive Inhibitory effect (>90% inhibition) of PMN adhesion to endothelial cells when NIF was used in combination with anti-CD11b monoclonal antibodies, which alone at saturating concentrations reduced PMN adhesion by only 50%. NIF also prevented aggregation of phorbol ester-stimulated JY lymphoblastoid cells that expressed only the functionally active CD11a, suggesting that NIF also can inhibit CD11a-dependent response. We transduced the NIF cDNA into human dermal microvessel endothelial cells in which NIF synthesis and release prevented PMN adhesion to the transduced human dermal microvessel endothelial cells. These data indicated that the potent antiadhesive effect of NIF may be the result of inhibition of CD11a and CD11b beta(2) integrins on PMNs. Moreover, the strategy of NIF release from transduced endothelial cells suggests the feasibility of blocking the CD11a- and CD11b beta(2) integrin-dependent PMN adhesion and PMN migration responses specifically at sites of endothelial cell activation.
Michael Krams - One of the best experts on this subject based on the ideXlab platform.
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acute stroke therapy by inhibition of Neutrophils astin an adaptive dose response study of uk 279 276 in acute ischemic stroke
Stroke, 2003Co-Authors: Michael Krams, Werner Hacke, Kennedy R Lees, Andrew P Grieve, Jeanmarc Orgogozo, Gary A FordAbstract:Background and Purpose— UK-279,276 (Neutrophil Inhibitory Factor) reduced infarct volume in a rat middle cerebral artery occlusion reperfusion model. ASTIN (Acute Stroke Therapy by Inhibition of Neutrophils) was an adaptive phase 2 dose-response–finding, proof-of-concept study to establish whether UK-279,276 improves recovery in acute ischemic stroke. The prime objective was to determine the dose that gave a clinically relevant effect in patients. Methods— A Bayesian sequential design with real-time efficacy data capture and continuous reassessment of the dose response allowed double-blind, randomized, adaptive allocation to 1 of 15 doses (dose range, 10 to 120 mg) or placebo and early termination for efficacy or futility. The primary end point was change from baseline to day 90 on the Scandinavian Stroke Scale (ΔSSS), adjusted for baseline SSS, aiming for a 3-point additional mean recovery above placebo. Results— Nine hundred sixty-six acute stroke patients (887 ischemic, 204 cotreated with intravenous t...
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effects of a selective cd11b cd18 antagonist and recombinant human tissue plasminogen activator treatment alone and in combination in a rat embolic model of stroke
Stroke, 2003Co-Authors: Li Zhang, Michael Krams, Zheng Gang Zhang, Rui Lan Zhang, Michael ChoppAbstract:Background and Purpose— We evaluated the neuroprotective effect of UK-279,276 (also referred to as recombinant Neutrophil Inhibitory Factor), a selective CD11b/CD18 antagonist, in combination with thrombolytic therapy on focal cerebral ischemia. Methods— Male Wistar rats (n=88) were subjected to embolic middle cerebral artery occlusion. Animals were randomly assigned to the following groups (n=11 in each group): vehicle treatment alone at 2 or 4 hours, UK-279,276 treatment alone at 2 or 4 hours, recombinant human tissue plasminogen activator (rhtPA) treatment alone at 2 or 4 hours, or the combination of UK-279,276 and rhtPA at 2 or 4 hours. Infarct volume, neurological function, hemorrhagic transformation, Neutrophil accumulation, and parenchymal fibrin deposition were measured 7 days after middle cerebral artery occlusion. Results— Treatment with UK-279,276 significantly (P<0.05) improved neurological severity scores, an index of neurological functional deficit, but had no effect on infarct volume compar...
D I Pritchard - One of the best experts on this subject based on the ideXlab platform.
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vaccination with Neutrophil Inhibitory Factor reduces the fecundity of the hookworm ancylostoma ceylanicum
Parasite Immunology, 2001Co-Authors: F Ali, Alan Brown, P Stanssens, L M Timothy, H R Soule, D I PritchardAbstract:Neutrophil Inhibitory Factor (NIF), a protein isolated from hookworms of the genus Ancylostoma, inhibits CD11b/18-dependent leucocyte function, binding to the I domain of CD11b. Historically, NIF was serendipitously isolated from whole worm extracts during a search for novel antihaemostatic agents, and little is known of its source or biological significance to the parasite. NIF has also been identified as a possible hookworm vaccine candidate. Ancylostomaceylanicum recombinant NIF, expressed in its active form in Pichia pastoris, was purified and its functional activity confirmed using Neutrophil adhesion assays and confirmatory immunoassay. Recombinant NIF was subsequently used in vaccination trials in the A. ceylanicum-hamster model system for human hookworm infection. Vaccinated and challenged animals were not protected in terms of worm burden or haematocrit values, despite the presence of high levels of specific antibody against NIF. However, adult worms resident in vaccinated animals showed a significant reduction in fecundity (85·8% by day 21 postinfection), indicating a degree of protection against subsequent transmission by vaccination. These data indicate that targeted vaccination with recombinant subunit material, derived from a known and effective immune suppressant secreted by the parasite, may offer partial protection against the transmission of hookworm infection. Furthermore, we can also report that a biological activity characteristic of NIF is detectable in the secretions of A.ceylanicum using two complementary bioassays. Complete neutralization of this secreted activity by vaccination in combination with other vaccine candidates may result in improved protection against A. ceylanicum infection.
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a survey of genes expressed in adults of the human hookworm necator americanus
Parasitology, 2000Co-Authors: Jennifer Daub, D I Pritchard, Alex Loukas, Mark BlaxterAbstract:Hookworms are gut-dwelling, blood-feeding nematodes that infect hundreds of millions of people, particularly in the tropics. As part of a program aiming to define novel drug targets and vaccine candidates for human parasitic nematodes, genes expressed in adults of the human hookworm Necator americanus were surveyed by the expressed sequence tag approach. In total 161 new hookworm genes were identified. For the majority of these, a function could be assigned by homology. The dataset includes proteases, protease inhibitors, a lipid binding protein, C-type lectins, an anti-bacterial Factor, globins and other genes of interest from a drug or vaccine development viewpoint. Three different classes of small, secreted proteins were identified that may be involved in the host–parasite interaction, including potential potassium channel blocking peptides. One third of the genes were novel. These included highly expressed, secreted (glyco)proteins which may be part of the excretory–secretory products of these important pathogens. Of particular interest are a family of 9 genes with similarity to the immunomodulatory protein, Neutrophil Inhibitory Factor, that may play a role in establishing an immunocompromised niche for this successful parasite.
Amin M Arnaout - One of the best experts on this subject based on the ideXlab platform.
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divergent response to lps and bacteria in cd14 deficient murine macrophages
Journal of Immunology, 2000Co-Authors: Kathryn J Moore, Amin M Arnaout, Lorna P Andersson, Robin R Ingalls, Brian G Monks, Rui Li, Douglas T Golenbock, Mason W FreemanAbstract:Gram-negative bacteria and the LPS constituent of their outer membranes stimulate the release of inflammatory mediators believed to be responsible for the clinical manifestations of septic shock. The GPI-linked membrane protein, CD14, initiates the signaling cascade responsible for the induction of this inflammatory response by LPS. In this paper, we report the generation and characterization of CD14-null mice in which the entire coding region of CD14 was deleted. As expected, LPS failed to elicit TNF-α and IL-6 production in macrophages taken from these animals, and this loss in responsiveness is associated with impaired activation of both the NF-κB and the c-Jun N-terminal mitogen-activated protein kinase pathways. The binding and uptake of heat-killed Escherichia coli , measured by FACS analysis, did not differ between CD14-null and wild-type macrophages. However, in contrast to the findings with LPS, whole E. coli stimulated similar levels of TNF-α release from CD14-null and wild-type macrophages at a dose of 10 bioparticles per cell. This effect was dose dependent, and at lower bacterial concentrations CD14-deficient macrophages produced significantly less TNF-α than wild type. Approximately half of this CD14-independent response appeared to be mediated by CD11b/CD18, as demonstrated by receptor blockade using Neutrophil Inhibitory Factor. An inhibitor of phagocytosis, cytochalasin B, abrogated the induction of TNF-α in CD14-deficient macrophages by E. coli . These data indicate that CD14 is essential for macrophage responses to free LPS, whereas other receptors, including CD11b/CD18, can compensate for the loss of CD14 in response to whole bacteria.
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solvent accessible residues on the metal ion dependent adhesion site face of integrin cr3 mediate its binding to the Neutrophil Inhibitory Factor
Journal of Biological Chemistry, 1996Co-Authors: Philippe Rieu, Takashi Sugimori, Diana L Griffith, Amin M ArnaoutAbstract:Abstract Neutrophil adhesion-dependent functions such as chemotaxis, spreading, and phagocytosis are inhibited by Neutrophil Inhibitory Factor (NIF), a glycoprotein produced by the hookworm Ancylostoma caninum. The NIF binding site has been localized to the A-domain of integrin CR3 (CD11b/CD18) and shown to be metal-dependent. The recently solved crystal structure of the A-domain from CD11b revealed a putative metal ion-dependent adhesion site (MIDAS) on the top of the structure. To determine if NIF binds to the A-domain at its MIDAS face, amino acid substitutions involving 24 residues present in surface loops and adjacent helices in the structure were created. The expressed CD11b A-domain and CR3 heterodimers were then tested in a blinded manner for their ability to bind to biotinylated NIF. The solvent-exposed Gly143, Asp149, Glu178-Glu179, and Arg208, all located on the MIDAS face, in close proximity to the metal ion, were involved in CR3-NIF interaction. These data show that the natural integrin antagonist, NIF, binds to CR3 through the MIDAS region and identify putative contact residues in this region that could be targeted therapeutically.