bluuebunny/crossref_metadata_2025 huggingface dataset:
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

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

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

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

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

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

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

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

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

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

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.
Elimination, blocking, and activation of macrophages: three of a kind?
Authors: van Rooijen Nico , Sanders Annemarie
Published: January 2018

In mammals, macrophages are multifunctional cells. Apart from their scavenger role in the clearance of nonself materials such as microorganisms and altered-self materials such as apoptotic cells, senescent erythrocytes, immune complexes, and inflammatory products, they play a crucial role in the regulation of both innate and acquired immunity. Whereas the former activity is based on phagocytosis and intracellular degradation, the latter activity largely depends on the production and secretion of a panel of regulatory molecules such as cytokines, chemokines, and nitrogen oxide (NO). Depletion of macrophages and blocking of phagocytosis form important approaches to study the role of these cells in various host defense mechanisms. Moreover, the efficacy of drug-and gene-targeting, based on the application of particulate carrier devices, can be improved in this way. However, compounds originally described as efficacious blockers of phagocytosis simultaneously activate their production of cytokines and NO. Moreover, elimination, blocking, as well as activation of macrophages are all dependent on the concentration of such compounds. When administered in vivo, they will reach some macrophages in a high and others in a low concentration. As a consequence, the former cells may be eliminated or blocked, whereas the latter are activated by the same treatment. In this review, the various methods for suppression of macrophage functions are compared and requirements for the development of new, selective, and organ-specific macrophage-suppressing devices are discussed.
Dietary fish oil diminishes the antigen presentation activity of rat dendritic cells
Authors: Sanderson Peter , MacPherson G Gordon , Jenkins Chris H , Calder Philip C
Published: January 2018

Rats were fed for 6 weeks on a low fat (LF) diet or on high fat diets containing safflower oil [SO; rich in n-6 polyunsaturated fatty acids (PUFAs)] or fish oil (FO; rich in n-3 PUFAs). Lymph-borne dendritic cells (L-DC) were isolated after cannulation of the thoracic duct and were used as antigen [keyhole limpet hemocyanin (KLH)] -presenting cells in an ex vivo assay that used KLH-sensitized spleen lymphocytes as the responder cells. FO feeding significantly diminished the antigen presentation activity of L-DC compared with L-DC from rats fed each of the other diets. The antigen presentation activity of L-DC from rats fed the SO diet was greater than that of L-DC from rats fed the LF diet. Feeding the FO diet significantly reduced both the proportion of CD2-positive L-DC and the level of CD2 expression on L-DC compared with feeding each of the other diets; the proportions of L-DC staining positive for CD40, CD18, CD54, CD11a, and MHC II were unaffected by diet. However, FO feeding reduced the level of expression of CD18, CD11a, MHC II, and CD54 on L-DC compared with feeding the other two diets; the level of expression of CD40 was unaffected by diet. This is the first study to report effects of dietary fatty acids on dendritic cells. The suppressive effect of FO feeding may account for some of the beneficial effects of n-3 polyunsaturated fatty acids observed in clinical settings, such as prolonged survival of grafts and diminished chronic inflammatory responses. However, such an effect may also be detrimental because host defense toward bacterial and other antigens could be compromised.
Induction and modulation of macrophage Ia antigen expression by platelet-activating factor
Authors: Erickson Kent L , Howard Angela D , Hubbard Neil E
Published: January 2018

Expression of major histocompatibility complex class II molecules, Ia, can be significantly augmented by interferon-γ (IFN-γ) in macrophages. In this study we demonstrate that platelet-activating factor (PAF) was also a potent inducer of Ia antigen expression on macrophages. PAF-induced Ia expression was both time- and dose-dependent. Maximal Ia expression was induced with 25 nM PAF after 3-h exposure to PAF. Ia expression in macrophages stimulated with PAF for 24 h was not significantly greater than unstimulated macrophages. Treatment of macrophages with IFN-γ and PAF did not affect either the kinetics or concentration required for maximal Ia expression induced by either IFN-γ or PAF. PAF-induced Ia expression was inhibited by the specific PAF receptor antagonists, WEB 2086, Ro 24-0238, and Ro 24-4637, indicating a receptor-mediated event Like IFN-γ-induced Ia expression, PAF activity was inhibited by prostaglandin E2 (PGE2). However, that expression was only inhibited after 24 h when macrophages were treated with the PGE2 synthesis inhibitors, flurbiprofen and indomethacin. These findings demonstrate that PAF, along with its role as a potent proinflammatory mediator, was also capable of inducing Ia expression on macrophages through the PAF receptor and that expression was altered by PGE2.
Effect of serine proteinase inhibitors on neutrophil function: α-1-proteinase inhibitor, antichymotrypsin, and a recombinant hybrid mutant of antichymotrypsin (LEX032) modulate neutrophil adhesion interactions
Authors: Carney David F , Jagels Mark A , Hugli Tony E , Sands Howard , Rubin Harvey
Published: January 2018

Circulating serine proteinase inhibitors (serpins) regulate a number of proteinases that participate in the inflammatory process. In this study, we investigated possible modulatory effects of serpins on neutrophil adhesion. Antichymotrypsin (ACT), α1-protease inhibitor (α1-PI), and LEX032, a recombinant hybrid of ACT and α1-PI were shown to inhibit neutrophil adhesion to fibronectin (FN)-coated surfaces and, to a lesser extent, adhesion to other extracellular matrix proteins. The inhibitory effect of serpins on neutrophil adhesion to FN was found to be related to inhibition of FN proteolysis based on the following observations: (1) elastase treatment of FN-coated plates, but not of neutrophils, resulted in enhanced neutrophil adhesion; and (2) serpins inhibited FN proteolysis by neutrophil proteases. Serpins also inhibited neutrophil spreading, as well as shedding of neutrophil CD43, but not L-selectin, CD18, or CD29. We conclude that serpins modulate neutrophil adhesion both by inhibiting proteolytic processing of extracellular matrix proteins and proteolytic shedding of CD43.
Anti-HIV-1 activity of indolicidin, an antimicrobial peptide from neutrophils
Authors: Robinson W Edward , McDougall Brenda , Tran Dat , Selsted Michael E
Published: January 2018

Indolicidin is a tridecapeptide amide isolated from the cytoplasmic granules of bovine neutrophils. It has potent, broad spectrum microbicidal activities in vitro that are thought to be related to the membrane-disruptive properties of the peptide. Based on the putative membrane-targeted mode of action, we postulated that indolicidin would be active against HIV-1, an enveloped virus. Indolicidin was reproducibly virucidal against HIV-1 at a concentration of 333 μg/mL (174 μM) with a 50% inhibitory dose between 67 and 100 μg/mL. At 37°, killing was rapid with >50% killing of HIV occurring within 5 min, and nearly 100% viral inactivation achieved by 60 min. The anti-HIV activity of indolicidin was temperature-sensitive, a finding consistent with a membrane-mediated antiviral mechanism. Parallel experiments revealed that indolicidin lysed cultured lymphoblastoid cells at concentrations similar to those required for antiviral activity. However, a des-R13-amide indolicidin analog (R12-OH), previously shown to have less antibacterial activity than indolicidin, was significantly less active against HIV and was non-toxic to lymphoid target cells at concentrations up to 333 μg/mL, the highest level tested.
Treatment of mice with anti-CD44 after allogeneic bone marrow cell transplantation is lethal
Authors: Zöller Margot , Föhr Nicole , Herrmann Karin
Published: January 2018

Because CD44 is known to be of functional importance in hematopoiesis, we were interested in whether anti-CD44 would interfere with syngeneic or allogeneic bone marrow cell engraftment. Syngeneic and allogeneic grafts were accepted by over 80% of mice. In both the syngeneic and the allogeneic host, homing, repopulation, and regain of immunoreactivity was delayed by anti-CD44 treatment. But in the syngeneic host the overall survival rate was unaltered. Instead, less than 25% of anti-CD44-treated, allogeneically reconstituted mice survived by recovery of the host's hematopoietic system, i.e. graft acceptance was close to 0%. The mice died between 4 and 15 days after engraftment and showed severe alterations of the gut. The high death rate of the allogeneically reconstituted mice was specific for anti-CD44 treatment. It did not depend on an ADCC mechanism, could not be abrogated by depletion of T cells, and was only mitigated by depletion of NK cells. According to the histological appearance of the gut, anti-CD44 strengthens a local (gut-associated) graft versus host reaction, which is not mediated by αβ T cells and at least not exclusively by NK cells. Because gut death is one of the major reasons for failure in allogeneic bone marrow transplantation, the model of anti-CD44-induced lethality offers itself to clarify the underlying mechanism.
The invasive and destructive behavior of HIV-induced T cell syncytia on collagen and endothelium
Authors: Sylwester Andrew , Daniels Karla , Soll David R
Published: January 2018

HIV-induced syncytia of the CD4+ SUP-T1 T cell line mimic the subcellular organization of single cells and are able to crawl like single cells through extension of giant pseudopods. Because syncytia have been demonstrated in lymphoid tissue of HIV-positive individuals, their behavior has been investigated on more natural substrata, including dehydrated collagen, hydrated collagen, endothelial monolayers, and endothelial monolayers grown on collagen cushions. On hydrated collagen gels, both individual SUPT1 cells and syncytia form unusually long cylindrical projections that possess pseudopodial ends and are highly dynamic. Syncytia penetrate collagen gels through extension of these projections and disrupt their integrity. When incubated on endothelium, both single cells and syncytia readily traverse the monolayer through holes, and when incubated on endothelium supported by a collagen cushion, syncytia generate large holes through the monolayer, penetrate the monolayer, and disrupt the collagen gel through extension of long, complex projections. Invading syncytia also release viruses in a polarized fashion which adhere to and are taken up in vesicles by the endothelium. It is suggested that the destructive behaviors of syncytia which have been demonstrated in vitro may have correlates in vivo.
CSF-1 (M-CSF) differentially sensitizes mononuclear phagocyte subpopulations to endotoxin in vivo: a potential pathway that regulates the severity of Gram-negative infections
Authors: Chapoval Andrei I , Kamdar Sonya J , Kremlev Sergey G , Evans Robert
Published: January 2018

CSF-1 is known to prime mononuclear phagocytes (MNP) for inflammatory stimuli in vitro. We hypothesized that CSF-1 in vivo can sensitize the host to the increased production of endotoxic shock mediators such as tumor necrosis factor α (TNF-α) and interleukin-6 (IL-6). Indeed, when CSF-1-primed mice were challenged with lipopolysaccharide (LPS), increased levels of serum IL-6 and TNF-α were detected. Both intravenous and intraperitoneal injections of CSF-1 resulted in increased sensitivity to LPS challenge, which induced maximum increases in serum IL-6 when administered via the intraperitoneal route. The peak serum IL-6 production in control and CSF-1-primed mice occurred 2–3 h after LPS injection, whereas that of TNF-α occurred by 1–2 h. When peripheral blood leukocytes, spleen cells, and resident peritoneal cells (PC) were isolated from CSF-1-primed mice injected with LPS, only the PC were shown to release IL-6 constitutively and none released TNF-α. A comparison of mRNA isolated from various cells and tissues after intraperitoneal CSF-1 priming indicated that only PC expressed IL-6 mRNA, whereas PC, liver, and spleen expressed TNF-α mRNA. All tissues showed increased levels of IL-6 and TNF-α mRNA in response to LPS challenge. Only liver and kidney showed an enhanced level of IL-6 expression in CSF-1-primed mice challenged with LPS, whereas liver, lung, and kidney showed enhanced TNF-α expression. These data indicate that CSF-1 primes tissue MNP but not circulating MNP to transcribe mRNA and release IL-6 and TNF-α. Overall, the data suggest that CSF-1 plays an important role in regulating the sensitivity of the host to the pathophysiological effects of endotoxin.
Effect of proteasome inhibitors on monocytic IκB-α and -β depletion, NF-κB activation, and cytokine production
Authors: Haas Monika , Page Sharon , Page Michael , Neumann Franz-Josef , Marx Nikolaus , Adam Michaela , Ziegler-Heitbrock H W Löms , Neumeier Dieter , Brand Korbinian
Published: January 2018

We investigated the effect of proteasome inhibitors on the lipopolysaccharide (LPS)-induced expression of several monocytic cytokines, which may be dependent on the transcription factor, nuclear factor-κB (NF-κB). Exposure of human monocytic THP-1 cells to ALLN and Mu873 prevented the LPS-induced degradation of IκB-α and -β, as did the more potent proteasome inhibitor, PSI, whereas several calpain inhibitors were ineffective. This was accompanied by the inhibition of nuclear NF-κB binding activity and NF-κB transcriptional activation. At the mRNA level, the inhibitors blocked the expression of tumor necrosis factor (TNF) and interleukin-1β (IL-1β), whereas IL-8 remained unaffected by ALLN and was only partially reduced by the highest dose of PSI. The latter effect appears to be due to an increase in IL-8 mRNA stability in the presence of proteasome inhibitors. Furthermore, the production of TNF was efficiently suppressed by ALLN and PSI, less by Mu873, and not at all by calpain inhibitors. In primary human blood monocytes ALLN also prevented the LPS-induced degradation of IκB-α and -β, efficiently blocked the production of TNF and, to a lesser extent, IL-1β, whereas that of IL-8 was not inhibited. The expression of NF-κB-dependent monocytic cytokines may be selectively controlled by the proteasome, offering a potential therapeutic target in inflammatory disease.
Platelets induce monocyte differentiation in serum-free coculture
Authors: Ammon C , Kreutz M , Rehli M , Krause S W , Andreesen R
Published: January 2018

Terminal maturation of blood monocytes (MO) in vitro and in vivo into macrophages (MAC) occurs as a result of interactions with various cell types. To characterize some of the cell-cell connections that maybe important for MO differentiation we cocultured human MO with lymphocytes and/or with platelets. We found that intact platelets strongly promoted MO maturation under serum-free conditions as evident from the expression of differentiation-dependent antigens and morphology. To further characterize the differentiation-inducing component(s) we prepared membrane and cytosol fractions of platelets. Both fractions could induce MO maturation, comparable to intact platelets. Further centrifugation of the cytosolic fraction revealed that only the pellet of ultracentrifugation, e.g., membrane fragments, could induce MO differentiation. Digestion with either trypsin or neuraminidase could only partially inhibit this effect. The same was true for heat-treated fractions, indicating that this platelet-derived differentiation stimulus is not solely an intact protein. Next we prepared protein and lipid fractions of platelets. Treatment of MO with platelet proteins or platelet lipids clearly showed that only the lipid components were able to induce MO maturation. We propose components present in the lipid fraction of platelet membranes as possible inducers of MO maturation in vitro.
Specific Th1 cell lines that confer protective immunity against experimental Borrelia burgdorferi infection in mice
Authors: Pride Michael W , Brown Eric L , Stephens L Clifton , Killion Jerald J , Norris Steven J , Kripke Margaret L
Published: January 2018

Although humoral responses to Borrelia burgdorferi (Bb) have been shown to be protective in some animal models of Lyme disease, the role of T cells in this disease is less well understood. This work describes three Bb-specific T cell lines that prevent disease progression in syngeneic mice. The T cell lines were generated in C3H mice immunized with Bb in complete Freund's adjuvant. All lines were Bb-specific, CD4+, TCRαβ+, and they proliferated and produced interferon-γ and interleukin-2 on stimulation with Bb. Injection of the cell lines into naive C3H recipients significantly reduced the number of organisms recoverable from the blood and tissues of infected mice and protected them from developing Bb-induced periarthritis. These studies demonstrated that Th1 cells can confer resistance to Bb infection in susceptible mice and suggested that the timing of this T cell response may be critical for determining disease outcome.
Neuropeptide regulation of proinflammatory cytokine responses
Authors: Dickerson Camille , Undem Bradley , Bullock Brandon , Winchurch Richard A
Published: January 2018

Severe traumatic injuries and infections are frequently accompanied by life-threatening shock and are associated with increases in the proinflammatory cytokines, particularly tumor necrosis factor α (TNF-α). The body's first perception of injury is the nociceptive or pain response. This response is induced at the site of injury and is transmitted systemically by sensory neuropeptides, the tachykinins, released from sensory afferent c-fiber neurons. We studied the role of tachykinins in regulating the production of proinflammatory cytokines induced by the administration of bacterial lipopolysaccharide. Destruction of terminal sensory nerve endings before lipopolysaccharide administration abrogates tachykinin synthesis and down-regulates TNF-α transcription and secretion. In contrast, the responses of interleukins-1 and -6 are unaffected. Pretreating animals with an antagonist for the substance P-specific NK-1 receptor also down-regulated the TNF-α response, whereas blockade of the NK-2 receptor had no effect. These findings indicate that substance P contributes to the induction of those cytokines that are involved in precipitating the shock response.
Interleukin-2 induces development of dendritic cells from cord blood CD34+ cells
Authors: Bykovskaja Svetlana N , Buffo Mary Jo , Bunker Mark , Zhang Haifan , Majors Alana , Herbert Mary , Lokshin Anna , Levitt Mark L , Jaja Andrew , Scalise Deborah , Kosiban Deborah , Evans Carol , Marks Stanley , Shogan Jeffrey
Published: January 2018

Dendritic cells (DC) have been shown to develop along a myeloid or lymphoid lineage of differentiation propagated from bone marrow or early thymic precursor cells with hematopoietic cytokines. In our study, we have induced growth and differentiation of DC from cord blood CD34+ cells initiated in interleukin-2 (IL-2) alone or in IL-2 + stem cell factor (SCF) + tumor necrosis factor α (TNF-α)-supplemented medium and cultured with IL-2 or IL-2 + SCF for 28–35 days. Dendritic morphology and antigenic phenotype of DC grown with IL-2 were characteristic for DC cultured in the presence of granulocyte-macrophage colony-stimulating factor (GM-CSF). Growth and differentiation of DC was followed by an increase in expression of MHC II and co-stimulating molecules CD80 and CD86. We have also shown the expression of the IL-2 receptor (IL-2R) γ-chain in CD34+ cells after 2–3 days of culture with IL-2 alone. The co-expression of the IL-2R α, β, and γ subunits in both DC cultured with IL-2- or GM-CSF-containing cocktail of cytokines was also shown. The time curve for induction of IL-2R demonstrated low levels of subunit expression at the beginning of culture. The number of CD1a cells coexpressing CD25, CD122, and CDγ increased to about 24–68 and to 78–95% after 21 and 28–35 days, respectively. Development of natural killer cells was shown along with DC. The proportion of CD56+ cells and cytotoxicity increased in a time-dependent manner.
Overview of interleukin-18: more than an interferon-γ inducing factor
Authors: Dinarello Charles A , Novick Daniela , Puren Adrian J , Fantuzzi Giamila , Shapiro Leland , Mühl Heiko , Yoon Do-Young , Reznikov Leonid L , Kim Soo-Hyun , Rubinstein Menachem
Published: January 2018

Initially described in 1989 as interferon-γ (IFN-γ) inducing factor (IGIF), interleukin-18 (IL-18) is a novel proinflammatory cytokine that is clearly more than an inducer of IFN-γ The cytokine possesses several biological properties such as activation of nuclear factor-κB (NF-κB), Fas ligand expression, the induction of both CC and CXC chemokines, and increased production of competent human immunodeficiency virus. Most activities are due to a receptor complex that recruits the IL-1 receptor-activating kinase (IRAK), leading to translocation of NF-κB. This property and others support the concept that IL-18 is related to the IL-1 family. Indeed, one of the IL-18 receptor chains is the IL-1 receptor-related protein, a member of the IL-1R family. In addition, IL-18 is structurally similar to IL-1β and like IL-1β is first synthesized as a leaderless precursor requiring the IL-1β converting enzyme for cleavage into an active molecule. The biology of IL-18 is reviewed in the overview and the implication for a role for this cytokine in disease is presented.
T cell development and activation in Jak3-deficient mice
Authors: Baird Allison M , Thomis Daniel C , Berg Leslie J
Published: January 2018

Jak3, a member of the Janus family of tyrosine kinases, participates in signaling through cytokine receptors that contain the common γ-chain, including the receptors for interleukin (IL)-2, IL-4, IL-7, IL-9, and IL-15. Jak3- and γc-deficient mice have pleiotropic defects that can be attributed to their inability to respond to multiple specific cytokines. A great deal of recent work has focused on the T cell defects in these mutant mice. Specifically, Jak3- and γc-deficient mice have small thymuses revealing a defect in T cell development, and in addition, have functionally unresponsive peripheral T cells with an activated/memory cell phenotype. The thymic defect in these mutant mice strongly resembles that seen in IL-7 and IL-7 receptor knockout mice, suggesting that the lack of IL-7 receptor signaling accounts for this defect in Jak3-/- and γc– mice. To characterize this defect further, we have examined the earliest stages of T cell development in adult and fetal Jak3-/- thymuses. These studies identify two discrete developmental defects at the CD4–CD8– stage of T cell maturation. Analyses of peripheral T cells in Jak3-/-and γc– mice have also revealed a number of abnormalities. All of the T cells in these mutant mice have an activated phenotype and a large fraction of them are proliferating in vivo. In addition, Jak3-/- and γc– T cells are more prone to undergo apoptosis than wild-type T cells. Together, these features account for the decreased IL-2 secretion by in vitro-stimulated Jak3-/- T cells. Overall, many of the lymphoid defects of Jak3- and γc-deficient mice can be accounted for by the lack of IL-7R and IL-2R signaling; however, other cytokine systems must also be involved in maintaining peripheral T cell homeostasis.
Differential regulation of endothelial cell adhesion molecule expression by nitric oxide donors and antioxidants
Authors: Spiecker Martin , Darius Harald , Kaboth Katharina , Hübner Felix , Liao James K
Published: January 2018

Although nitric oxide (NO) and antioxidants inhibit adhesion molecule expression, their inhibitory effects on nuclear factor κB (NF-κB) activation may differ. The NO donors, but not 8-bromo-cGMP, decreased tumor necrosis factor α (TNF-α)-induced VCAM-1, ICAM-1, and E-selectin expression by 11-70%. In contrast, NAC completely abolished VCAM-1 and E-selectin expression and decreased ICAM-1 expression by 56%. Gel shift assays demonstrate that NF-κB activation was inhibited by both NO and antioxidants. The activation of NF-κB involves the phosphorylation and degradation of its cytoplasmic inhibitor IκB-α by 26S proteasomes. The 26S proteasome inhibitor MG132 prevented the degradation of phosphorylated IκB-α. NAC inhibited IκB kinase (IKK) activity and prevented IκB-α phosphorylation and degradation. In contrast, NO did not inhibit IKK activity, IκB-α phosphorylation, or IκB-α degradation. However, NO, but not antioxidants, induced IκB-α promoter activity. The inhibitory effects of NO on adhesion molecule expression, therefore, differs from that of antioxidants in terms of the mechanism by which NF-κB is inactivated.
Hypoxia down-regulates MCP-1 expression: implications for macrophage distribution in tumors
Authors: Negus Rupert P M , Turner Lynn , Burke Frances , Balkwill Frances R
Published: January 2018

Monocyte chemoattractant protein 1 (MCP-1) is likely to contribute to the macrophage infiltrate in human ovarian carcinomas. Although MCP-1 is predominantly expressed by the tumor parenchyma, macrophages accumulate at highest density in necrotic regions, which are associated with low oxygen tensions. Tumor necrosis factor α (TNF-α) can stimulate MCP-1 production and is also present within ovarian carcinomas. We have investigated the effect of hypoxia both on MCP-1 expression in ovarian cancer cell lines and monocyte migration. Hypoxia down-regulated TNF-α-induced MCP-1 mRNA and protein production by ovarian cancer cells. The effect was mimicked by cobalt chloride and desferrioxamine, consistent with a specific oxygen-sensing mechanism. Unlike antioxidants, hypoxia did not inhibit nuclear factor κB mobilization. Monocyte migration in response to MCP-1 was also diminished under hypoxic conditions. Down-regulation of MCP-1 expression and the inhibition of monocyte migration are independent effects of hypoxia that may contribute to the distribution of macrophages within ovarian tumors.
CD28-mediated activation in CD45RA+ and CD45RO+ T cells: enhanced levels of reactive oxygen intermediates and c-Rel nuclear translocation in CD45RA+ cells
Authors: Lahdenpohja Nina , Hurme Mikko
Published: January 2018

We have analyzed the effect of complete T cell activation (anti-CD3 plus anti-CD28) on the activation of NF-κB in CD45RA+ (naive) and CD45RO+ (memory/effector) T cells. Long exposure (24 h) induced stronger NF-κB DNA binding in CD45RA+ cells than in CD45RO+ cells. Analysis of the nuclear c-Rel protein indicated that after anti-CD3+anti-CD28 stimulation the level of c-Rel was higher in CD45RA+ cells. Analysis of the cytoplasmic inhibitor IκBα indicated that anti-CD3+anti-CD28 stimulation induced a long-lasting degradation in CD45RA+ cells but in CD45RO+ cells the degradation process was more rapid. Because the CD28 costimulus is known to induce the production of reactive oxygen intermediates (ROIs), the intracellular ROI levels in CD45RA+ and CD45RO+ cells were compared by flow cytometry. ROIs were produced in both cell types, but more strongly in CD45RA+ cells. The data presented in this study further emphasize the differences between CD45RA+ and CD45RO+ T lymphocytes in ROI-dependent signaling pathways.
The bactericidal/permeability-increasing protein (BPI) in antibacterial host defense
Authors: Elsbach Peter
Published: January 2018

The bactericidal/permeability-increasing protein (BPI) is a 456-residue cationic protein produced only by precursors of polymorphonuclear leukocytes (PMN) and is stored in the primary granules of these cells. The potent (nM) cytotoxicity of BPI is limited to gram-negative bacteria (GNB), reflecting the high affinity (<10 nM) of BPI for bacterial lipopolysaccharides (LPS). The biological effects of isolated BPI are linked to complex formation with LPS. Binding of BPI to live bacteria via LPS causes immediate growth arrest. Actual killing coincides with later damage to the inner membrane. Complex formation of BPI with cell-asssociated or cell-free LPS inhibits all LPS-induced host cell responses. BPI-blocking antibodies abolish the potent activity of whole PMN lysates and inflammatory fluids against BPI-sensitive GNB. The antibacterial and the anti-endotoxin activities of BPI are fully expressed by the amino terminal half of the molecule. These properties of BPI have prompted preclinical and subsequent clinical testing of recombinant amino-terminal fragments of BPI. In animals, human BPI protein products protect against lethal injections of isolated LPS and inocula of GNB. Phase I trials in healthy human volunteers and multiple Phase I/II clinical trials have been completed or are in progress (severe pediatric meningococcemia, hemorrhagic trauma, partial hepatectomy, severe peritoneal infections, and cystic fibrosis) and two phase III trials (meningococcemia and hemorrhagic trauma) have been initiated. In none of >900 normal and severely ill individuals have issues of safety or immunogenicity been encountered. Preliminary evidence points to overall benefit in BPI-treated patients. These results suggest that BPI may have a place in the treatment of life-threatening infections and conditions associated with bacteremia and endotoxemia. J. Leukoc. Biol. 64: 14–18; 1998.
Transferrin receptor in T cell activation and transplantation
Authors: Bayer Allison L , Baliga Prabhakar , Woodward Jennifer E
Published: January 2018

Transferrin receptor (TfR) expression is up-regulated during T cell activation after the interaction of the T cell receptor with the antigen-major histocompatibility complex and the expression of interleukin-2 (IL-2) receptor. We hypothesize that anti-TfR monoclonal antibody (mAb) will prolong allograft survival by altering T cell responses. In a murine heterotopic nonvascularized cardiac allograft model, CBA/J (H-2k) recipients were transplanted with neonatal C57BL/6 (H-2b) donor hearts. Anti-TfR or isotype-matched control mAbs (100 μg) were administered at the time of transplantation and on the following day. Splenocytes from naive CBA/J mice were stimulated in vitro with C57BL/6 alloantigen. Anti-TfR mAb was administered at 5 μg/mL during the initiation of culture. Cytotoxic T lymphocyte (CTL) and mixed lymphocyte responses (MLR) were performed to assess T cell function. After 24 h in culture, cells were harvested, RNA isolated, and semi-quantitative reverse transcriptase-polymerase chain reaction performed. Anti-TfR mAb prolonged allograft survival to 25.7 ± 0.9 days compared to the isotype control (10.7 ± 0.4 days, P < 0.01, Wilcoxon rank sum). Anti-TfR mAb completely abrogated the CTL response and suppressed the MLR by 70–86% compared to the isotype controls. Anti-TfR mAb suppressed IL-2, interferon-γ (IFN-γ), IL-10, and IL-12 p40 mRNA expression, but had no effect on IL-4, IL-12 p35, and IL-15 mRNA expression. In conclusion, anti-TfR mAb prolongs allograft survival, suppresses T cell function, and alters IL-2, IL-10, IL-12 p40, and IFN-γ mRNA expression. These data suggest that the down-regulation in IL-12 mRNA by anti-TfR mAb may prevent the development of T helper cells, thereby promoting graft survival and altering cell-mediated immune responses. The partial effect by anti-TfR mAb on cytokine mRNA expression may be due to other contributing factors such as costimulation. J. Leukoc. Biol. 64: 19–24; 1998.
Small molecule inhibitor of HIV-1 cell fusion blocks chemokine receptor-mediated function
Authors: Howard O M Z , Korte Thomas , Tarasova Nadya I , Grimm Michael , Turpin Jim A , Rice William G , Michejda Christopher J , Blumenthal Robert , Oppenheim J J
Published: January 2018

The intersection of the HIV and the chemokine fields began with the observation that HIV entry into cells could be blocked by certain chemokines. Subsequent work showed that HIV entry is dependent on the presence of specific chemokine receptors. These observations led us to evaluate a series of compounds, ureido analogs of distamycin previously reported to block HIV entry into cells in vitro, for chemokine antagonist activity. One of the distamycin analogs, 2,2′[4,4′-[[aminocarbonyl]amino]bis[N,4′-di[pyrrole-2-carboxamide-1,1′-dimethyl]]-6,8 napthalenedisulfonic acid] hexasodium salt (NSC 651016), is shown here to inhibit syncytia formation and cell fusion. Mechanistic studies showed that this inhibition was not due to conformational changes in gp120-gp41 induced by target cell CD4 and chemokine co-receptor and was therefore not due to interference with binding of HIV-1. Additional mechanistic studies demonstrated that NSC 651016 inhibited chemokine binding to specific chemokine receptors, induced CXCR4 and CCR5 receptor internalization, and inhibited chemokine-induced chemotaxis by macrophage inflammatory protein (MIP)-1α, MIP-1β, RANTES, and stromal-derived factor-1α but not monocyte chemotactic protein-1. Thus, we describe a novel compound that inhibits in vivo replication of HIV-1 by down-regulation of co-receptors. These data lead us to propose that NSC 651016 may have in vivo anti-inflammatory activity. J. Leukoc. Biol. 64: 6–13; 1998.