bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preactivation exposure of RAW 264.7 cells to taurine chloramine attenuates subsequent production of nitric oxide and expression of iNOS mRNA
Authors: Park Eunkyue , Schuller-Levis Georgia , Jia Jun-Hua , Quinn Michael R 
Published: January 2018

Abstract
Recent studies demonstrate that taurine chloramine (Thu-Cl) inhibits production of nitric oxide (NO) and other proinflammatory mediators in cultured macrophages when added to the media at the time of activation. Because Thu-Cl may react with various media constituents and it is difficult to measure Thu-Cl in complex solutions, we designed experiments to more carefully control cell exposure to various chloramines and NaOCl. RAW 264.7 cells were exposed to 1 mM of NaOCl, Thu-Cl, or chloramine preparations of the following amino acids: l-alanine (l-Ala-Cl), β-alanine (β-Ala-Cl), serine (Ser-Cl), or glycine (Gly-Cl) in Hanks' balanced salt solution (HBSS) for up to 2 h (37°C, 5%CO2). The HBSS solution was then replaced with complete media containing interferon-γ (IFN-γ) and lipopolysaccharide (LPS) for an additional 24 h before measuring cell viability. The chemical stability of NaOCl and each chloramine was evaluated after various times of preactivation exposure by measuring retention of each solution's UV absorption spectra and ability to oxidize KI. Cytotoxicity of each solution was evaluated by the maintained ability of RAW 264.7 cells to reduce MIT. Whereas Thu-Cl, β-Ala-Cl, and Gly-Cl were stable chloramines, only Thu-Cl was not cytotoxic. l-Ala-Cl, Ser-Cl, and the highly reactive oxidant NaOCl were unstable and toxic. In further studies RAW 264.7 cells were exposed to Thu-Cl in HBSS for 2 h and the solution was then replaced with complete media containing IFN-γ and LPS, taxol, lipoarabinomannan, or interleukin-2. Production of NO was measured 24 h later and was inhibited in activated cells that were previously exposed to Thu-Cl. Inhibition of NO production was dependent on Thu-Cl concentration and was accounted for by reduced expression of inducible nitric oxide synthase mRNA, regardless of activator combinations. These results support the idea that Thu-Cl has the potential to function as an inhibitory modulator of inflammation.
Dexamethasone-induced suppression of apoptosis in human neutrophils requires continuous stimulation of new protein synthesis
Authors: Cox Gerard , Austin Richard C 
Published: January 2018

Abstract
We examined the mechanisms of corticosteroid inhibition of cell death by apoptosis in human neutrophils. Suppression of apoptosis by dexameth-asone was abolished by co-treatment with the protein synthesis inhibitor cycloheximide. At doses of 1 μg/mL cycloheximide did not reduce basal survival of neutrophils but effectively inhibited dexamethasone-induced increases in 24-h survival (24.4 ± 8.7 vs. 49.6 ± 10%, P &lt; 0.01). Similar results were obtained with actinomycin D, an inhibitor of mRNA synthesis. The factor(s) responsible for mediating increased survival following dexamethasone treatment is not active extracellularly because dexamethasone-treated neutrophil-conditioned medium (CM) had no effect on the survival of naive neutrophils when the direct effects of dexamethasone were neutralized with the steroid antagonist RU-486. In contrast, LPS-treated neutrophil CM significantly increased neutrophil survival even after addition of polymyxin b. The survival effect of dexamethasone required the continuous presence of the agonist because addition of RU-486 caused prompt development of apoptosis in dexamethasone-treated cells. When naive and dexamethasone-treated cells were examined by mRNA differential display, a limited number of cDNA bands were consistently and reproducibly detected that were increased in intensity, indicating up-regulation by dexamethasone. Thus, corticosteroid regulation of neutrophil apoptosis is a specific effect that depends on continuous stimulation of synthesis of a (protein) survival factor.
Secretion and inactivation of myeloperoxidase by isolated neutrophils
Authors: King Charles C , Jefferson M Margaret , Thomas Edwin L 
Published: January 2018

Abstract
Neutrophils prevent infection by ingesting and killing microorganisms but oxidants and proteases released by neutrophils damage host tissues. Our aim was to identify factors that regulate oxidant production by the enzyme myeloperoxidase (MPO) following secretion of MPO into the medium. Cells stimulated with phorbol myristate acetate (PMA) or opsonized zymosan particles secreted MPO and released superoxide free radicals (·O2-). Dismutation of ·O2- produced hydrogen peroxide (H2O2) and MPO catalyzed the oxidation of chloride ion by H2O2 to produce the toxic oxidant hypochlorous acid (HOCl). Adding the enzyme superoxide dismutase (SOD) to increase the rate of conversion of ·O2- to H2O2 had pH-dependent effects on HOCl production. From pH 6.0 to 7.4, SOD promoted HOCl production by up to 500% but SOD had no effect at pH 7.6 and inhibited by 40 ± 10% at pH 7.8. In further experiments at pH 7.0, MPO activity in the cells decreased by 25 ± 2 and 44 ± 4% during 1-h incubations with PMA and zymosan. Only 1 ± 0 and 3 ± 1% of the total activity was found in the medium, indicating that most of the secreted MPO was inactivated. Loss of activity was not accompanied by proteolytic destruction of the MPO protein, which was measured with anti-MPO antibodies. SOD raised the amount of active MPO in the medium two- to sevenfold, but adding deferoxamine to chelate iron or adding ferric ion had no effect. The ionophore A23187 was as effective as zymosan as a stimulus for MPO secretion but ·O2- production by ionophore-stimulated cells was less than 4% of that of PMA- or zymosan-stimulated cells and most of the secreted MPO was found active in the medium. When PMA-stimulated cells were incubated with purified MPO, the added MPO activity was lost from the medium. Binding or proteolysis did not account for loss of activity as indicated by recovery of added radioiodinated MPO from the medium. The visible absorption spectrum of MPO was lost, indicating destruction of the iron-containing prosthetic group. Loss of activity and loss of the MPO spectrum were blocked by SOD but not by deferoxamine or catalase. The results indicate that, in the physiological pH range, inactivation of MPO in the medium suppressed HOCl production. Inactivation required ·O2- but not HOCl, H2O2, or free iron. Inactivation of secreted MPO may limit MPO-mediated damage to host tissues by stimulated neutrophils.
Immunoelectron microscopy shows a clustered distribution of NADPH oxidase components in the human neutrophil plasma membrane
Authors: Wientjes Frans B , Segal Anthony W , Hartwig John H 
Published: January 2018

Abstract
The NADPH oxidase that produces superoxide in professional phagocytic cells is a flavocytochrome b electron transport chain in the membrane, a heterodimer of gp91phox and p22phox, that is activated by a number of cytosolic proteins, including p47phox p67phox, and the small GTP-binding protein p21rac, which translocate to the membrane and attach to the flavocytochrome on activation. The components of this oxidase were localized on the cytoplasmic surface of the plasma membrane of adherent unroofed neutrophils by immunolabeling. Components of the NADPH oxidase and p21rac were found together in punctate clusters occupying 0.03–0.1 μm2 of the cytoplasmic surface of the plasma membrane where the density of labeling of the cytosolic components was increased after stimulation with phorbol myristate acetate.
Sequential potentiation and inhibition of PMN reactivity by maximally stimulated platelets
Authors: Aziz Khalil A , Cawley John C , Treweeke Andrew T , Zuzel Mirko 
Published: January 2018

Abstract
In a recent study, we showed that granulocyte-macrophage colony-stimulating factor (GM-CSF) and supernatants from partially stimulated platelets undergoing selective α-granule release synergistically enhanced polymorphonuclear leukocyte (PMN) response to N-formyl-methionyl-leucyl-phenylalanine (fMLP). The active factor released from platelet α-granules was identified as platelet factor four (PF4). In this study we investigate the joint effect on PMN reactivity of GM-CSF and supernatants from platelets maximally stimulated to release both α- and dense granule contents. These platelet supernatants enhanced PMN chemiluminescence (CL; a measure of the oxidative burst) during short incubations, whereas longer incubations led to the loss of this enhancement and the prevention of PMN priming by GM-CSF. The platelets derived inhibitory factor was of low molecular weight, originated from the dense granule precursor(s), and its generation required the presence of PMN. When ATP/ADP were incubated with PMN at concentrations found in platelet-dense granules, they produced a similar biphasic effect on PMN reactivity (a potentiation followed by inhibition) as seen with the platelet supernatants. The inhibitory effect of these nucleotides coincided with their conversion to AMP. AMP per se had an immediate inhibitory effect on PMN response to fMLP and prevented PMN priming by GM-CSF. This study confirms that partially stimulated platelets enhance PMN reactivity. However, during maximal stimulation, nucleotides released from the platelet-dense granules are converted to AMP, which in turn can counteract the PMN priming effects of factors such as PF4 and GM-CSF.
Cytokine production by dengue virus antigen-responsive human T lymphocytes in vitro examined using a double immunocytochemical technique
Authors: Mori Masuko , Kurane Ichiro , Janus Jurand , Ennis Francis A 
Published: January 2018

Abstract
A number of studies suggest that cytokines may contribute to the pathogenesis of viral infections, including dengue. In this study, we developed a double immunocytochemical method and characterized cytokine-producing cells in the peripheral blood mononuclear cells (PBMC) of dengue virus-immune donors after in vitro stimulation with specific dengue antigens. We found that double immunostaining using immunoalkaline phosphatase (Vector blue) for cytokines [interferon-γ (IFN-γ), interleukin (IL) -2, -4, -1α, -1β, and -6, tumor necrosis factor β (TNF-β), and TNF-α] and immunoperoxidase [diaminobenzidine (DAB)] for cell surface markers (CD3, CD4, CD8, CD20, and CD68) provided the best distinction of double-positive cells from single-positive or -negative cells. The number of IFN-γ, IL-2, IL-4, and TNF-β-positive cells increased 2 or 3 days after stimulation with specific dengue antigens. No or very few cytokine-producing cells were detected in the PBMC of non-immune donors stimulated with dengue antigens and the PBMC of immune donors stimulated with a control antigen. The analysis of cell surface markers showed that mainly CD4+ and CD8+ T cells produced these cytokines. The results obtained by immunocytochemistry were consistent with cytokine levels detected in the culture medium assayed by enzyme-linked immunosorbent assay. In conclusion, this double immunocytochemistry technique is suitable for the detection and characterization of cytokine-producing cells in PBMC. Furthermore, the results support the hypothesis that antigen-stimulated CD4+ and CD8+ T cells produce cytokines that may play a role in the pathogenesis of dengue virus infection.
Human neutrophil elastase abolishes interleukin-8 chemotactic activity
Authors: Leavell Keith J , Peterson Michael W , Gross Thomas J 
Published: January 2018

Abstract
A large body of literature supports the role of interleukin-8 (IL-8) in inflammatory lung disease. Numerous factors induce the local synthesis and secretion of this potent chemokine leading to the recruitment and activation of polymorphonuclear leukocytes. However, little is currently known about the fate of IL-8 secreted at sites of inflammatory injury. We have found that incubation of recombinant human IL-8 with purified human neutrophil elastase (HNE) results in the loss of IL-8 chemotactic activity in a dose- and time-dependent fashion. This loss in bioactivity is accompanied by a similar loss of IL-8 immunoreactivity. Western blot analysis revealed that IL-8 chemotactic activity is lost by proteolysis of the parent molecule into undetectable small fragments. The terminal digestion of IL-8 was specific to HNE as no loss of bioactivity was observed with equimolar concentrations of the serine proteases urokinase, plasmin, thrombin, or cathepsin G. This effect on chemotactic activity is not limited to recombinant IL-8 because HNE also digested IL-8 secreted by human monocytes. HNE-mediated proteolysis offers a novel mechanism for down-regulating the inflammatory cascade initiated by IL-8.
Macrophage-parasite relationship in theileriosis. Reversible phenotypic and functional dedifferentiation of macrophages infected with Theileria annulata
Authors: Sager Heinz , Davis William C , Dobbelaere Dirk A E , Jungi Thomas W 
Published: January 2018

Abstract
Theileria annulata is a tick-transmitted protozoan parasite of cattle, which transforms cells of macrophage (Mɸ) or B cell lineage. Bone marrow cells, bone marrow cell-derived, and monocyte-derived Mɸ were infected with T. annulata sporozoites, and the resulting cell lines were assessed for surface marker expression and function. Transformed lines expressed histocompatibility complex (MHC) class-I and II, CD44, CD45, and the myeloid marker DH598-surface markers CD14, CD11b, M-M7, TH57A, and to a lesser extent CD11a/CD18, CD11c, and ACT(B), were down-regulated. Likewise, transformed cells failed to express Mɸ functions (Fc-receptor-mediated phagocytosis, phorbol myristate acetate-induced oxidative burst, lipopolysaccharide-induced tumor necrosis factor α, and nitric oxide generation and procoagulant activity up-regulation). Mɸ origin was assured by homogeneity of the starting population, cloning of cells by limiting dilution, and repeated microscopic and flow cytometric monitoring of the cell lines. Elimination of the parasite by treatment with BW720c resulted in the reacquisition of monocyte lineage properties, as evidenced by up-regulation of CD14, and by re-acquisition of the capacity to ingest opsonized sheep red blood cells and bacteria. Thus, Mɸ transformed by T. annulaia appear to undergo a process of parasite-induced dedifferentiation but reassume the differentiated phenotype upon elimination of the parasite.
Phospholipase D mediates Fcγ receptor activation of neutrophils and provides specificity between high-valency immune complexes and fMLP signaling pathways
Authors: Gewirtz Andrew T , Simons Elizabeth R 
Published: January 2018

Abstract
Neutrophils phagocytize high-valency immune complexes (HIC) by an Fcγ receptor-mediated mechanism, activating an oxidative burst and initiating degranulation. In contrast, neutrophils exhibit chemotaxis to N-formylated peptides [e.g., N-formylmethionyl-leucyl-phenylalanine (fMLP)] and secrete far fewer oxidants or granule contents than neutrophils activated by HIC. However, if neutrophils are treated with cytochalasin B (CB) or permeabilized with streptolysin O, chemoattractant-induced neutrophil secretion is increased to a level beyond that observed in response to HIC. Because priming neutrophils with CB, or permeabilizing them, also augments activation of phospholipase D (PLD) in response to fMLP, we reasoned that, in intact (i.e., nonpermeabilized) unprimed neutrophils, PLD may participate in a signaling pathway specific to phagocytic stimuli such as HIC and hence may contribute to degranulation control. PLD activity in response to HIC and fMLP correlated closely with stimulus-induced azurophilic degranulation under a wide variety of experimental conditions, including compounds that abrogated or augmented stimulus-induced PLD action. PLD activation preceded, and appeared to be necessary for, azurophilic degranulation. These results suggest that PLD may play a central role in controlling azurophilic degranulation and provide signaling specificity between pathways activated by fMLP and HIC in intact neutrophils.
Chemokine receptors and HIV
Authors: Broder Christopher C , Collman Ronald G 
Published: January 2018

Abstract
The discovery that chemokine receptors are the human cofactors required along with CD4 for fusion and infection by HIV has opened new directions in AIDS research on mechanisms of viral entry, tropism, and pathogenesis. A possible mechanism of coreceptor function has been demonstrated that involves the formation of a complex on the cell surface between the HIV-1 envelope, CD4, and the coreceptor. Functional studies indicate that this interaction is structurally complex, that it probably involves multiple domains of the coreceptor, and that different virus isolates interact with coreceptors in distinct ways. Other immunodeficiency viruses including simian immunodeficiency virus and feline immunodeficiency virus also utilize chemokine receptors for entry. The identification of genetic polymorphisms helps explain why some people, with alterations in the CCR5 gene that prevent expression, are protected from HIV-1 infection. The discovery of specific HIV-1 fusion coreceptor molecules has not only provided new insights into the mechanisms of viral entry and tropism, but also led to new avenues of investigation on strategies to block HIV infection.
Induction of cytokines by HIV-1 and its gp120 protein in human peripheral blood monocyte/macrophages and modulation of cytokine response during differentiation
Authors: Gessani Sandra , Borghi Paola , Fantuzzi Laura , Varano Barbara , Conti Lucia , Puddu Patrizia , Belardelli Filippo 
Published: January 2018

Abstract
We previously reported that in vitro culture of human peripheral blood monocytes resulted in a time-dependent differentiation into macrophages and in an enhanced capacity for producing certain cytokines [i.e., tumor necrosis factor α, interleukin-6 (IL-6), and interferon-β (IFN-β)] in response to bacterial lipopolysaccharide (LPS). HIV-1 infection or gp120 treatment of monocyte/macrophages resulted in the induction of low levels of DFN-β, which were very effective in restricting viral replication in 7-day cultured macrophages but not in freshly isolated cells. This enhanced response of macrophages was due to a higher sensitivity of these cells to the antiviral effect of IFN-β. Consistent with this finding, 7-day cultured macrophages exhibited higher levels of type I IFN receptors than 1-day cultured monocytes. Treatment of monocyte/macrophages with gp120 also caused a marked increase in IL-10 secretion, regardless of the differentiation state. No IL-12 secretion was detected in monocyte/macrophage cultures treated with gp120 alone. However, consistent IL-12 secretion was found in 7-day cultured macrophages primed with IFN-β and subsequently stimulated with gp120. Macrophages responded more efficiently than monocytes to the priming effect of IFN-β for IL-12 production. This was consistent with a stronger antiviral response against vesicular stomatitis virus by these cells as well as with a higher expression of IFN-β receptors. The finding that the acquisition of the macrophage phenotype is associated with an increased capacity to respond to environmental signals (such as type I and type II IFNs) underlines the importance of the differentiation process for the selection of a certain repertoire of responses that may allow these cells to have important functions in vivo.
Infection of gastrointestinal tract macrophages by HIV-1
Authors: Smith Phillip D , Meng Gang , Shaw George M , Li Ling 
Published: January 2018

Abstract
As the largest lymphoid organ and the largest reservoir of macrophages in the body, the gastrointestinal tract mucosa is probably the largest organ reservoir of macrophages infected with HIV-1. To elucidate the biology of HIV-1 infection of intestinal macrophages, we isolated lamina propria macrophages from normal human jejunum by neutral protease digestion, purified the cells by counterflow centrifugal elutriation, and then infected the cells with HIV-1. The lamina propria macrophages were permissive to macrophage-tropic isolates of HIV-1 and substantially less permissive to lymphocyte-tropic isolates. Compared with blood monocytes, mucosal macrophages produced 2–3 logs less p24 antigen at peak infection. The reduced level of infection was not due to impaired macrophage viability, reduced CD4 expression, or the isolation procedure. These results confirm that macrophages isolated from the gastrointestinal tract mucosa can support HIV-1 production, albeit at a lower level than blood monocytes. The reduced level of virus production may reflect the unique biology of intestinal lamina propria macrophages.
Human neutrophils secrete vascular endothelial growth factor
Authors: Taichman Norton S , Young Sylvia , Cruchley Alan T , Taylor Peter , Paleolog Ewa 
Published: January 2018

Abstract
Vascular endothelial growth factor (VEGF) is a multifunctional cytokine that plays a pivotal role in mediating neovascularization as well as other endothelial cell alterations during inflammation. In this study, we demonstrate that human neutrophils are a source of VEGF. We observed that isolated blood neutrophils released VEGF in response to different stimuli and we demonstrated by immunohistochemistry that neutrophils infiltrating inflamed tissues contain VEGF. These results indicate that neutrophil-derived VEGF may be instrumental in regulating vascular responses during acute and chronic inflammation.
Pervanadate-induced adhesion of CD4+ T cell to fibronectin is associated with tyrosine phosphorylation of paxillin
Authors: Miron Shmuel , Kachalsky Sylvia G , Hershkoviz Rami , Lider Ofer 
Published: January 2018

Abstract
The initial stages of T cell activation involve tyrosine protein kinase-mediated intracellular signaling events. Integrin-mediated adhesion pf CD4+ T lymphocytes to extracellular matrix glycoproteins, such as fibronectin, is an activation-dependent process. The involvement of tyrosine protein kinases in the adhesion of CD4+ T cells to fibronectin was examined using pervanadate, a protein-tyrosine phosphatase inhibitor. Pervanadate induced the adhesion of human CD4+ T cells to immobilized fibronectin in a β1integrin-mediated fashion, and adhesion was associated with an increase of protein tyrosine phosphorylation. Tyrosine protein kinase inhibitors abrogated both T cell adhesion and intracellular protein tyrosine phosphorylation. Participation of cytoskeletal proteins in the pervanadate-induced T cell adhesion was indicated because cytoskeleton disruption by cytochalasin B inhibited cell adhesion to fibronectin. We demonstrate that the cytoskeletal protein paxillin underwent time-dependent tyrosine phosphorylation simultaneously with pervanadate-induced T cell adhesion to fibronectin. Tyrosine phosphorylation of paxillin was related to cell adhesion, since pretreatment of T cells with cytochalasin B abrogated both adhesion and phosphorylation. This study demonstrates a correlation between activation of protein tyrosine kinases, tyrosine phosphorylation of paxillin, and integrin-mediated T cell adhesion to extracellular matrix glycoproteins.