bluuebunny/crossref_metadata_2025_split huggingface dataset:
Immunogenicity of the Extracellular Domains of C-C Chemokine Receptor 5 and the In Vitro Effects on Simian Immunodeficiency Virus or HIV Infectivity
Authors: Lehner Thomas , Doyle Carl , Wang Yufei , Babaahmady Kaboutar , Whittall Trevor , Tao Louisa , Bergmeier Lesley , Kelly Charles 
Published: April 2014

AbstractThe C-C chemokine receptor CCR5 serves an important function in chemotaxis of lymphocytes, monocytes, and dendritic cells. CCR5 is also the major coreceptor in most macrophage-tropic HIV-1 infections. Immunization of rhesus macaques with a baculovirus-generated CCR5 construct or peptides derived from the sequences of the four extracellular domains of CCR5 elicited IgG and IgA Abs, inhibition of SIV replication, and CD4+ T cell proliferative responses to three of the extracellular domains of CCR5. The immune sera reacted with cell surface CCR5 expressed on HEK 293 cells. T and B cell epitope mapping revealed major and minor T and B cell epitopes in the N-terminal, first, and second loops of CCR5. The three C-C chemokines, RANTES, macrophage-inflammatory protein-1α, and macrophage-inflammatory protein-1β, were up-regulated by immunization with the CCR5-derived peptides, and the cell surface expression of CCR5 was decreased. The CCR5 Abs were complementary to the C-C chemokines in inhibiting HIV replication in vitro. Immunization with the four extracellular domains of CCR5 suggests that three of them are immunogenic, with maximal T cell responses being elicited by the second loop peptide. However, maximal Abs to the cell surface CCR5 or viral inhibitory Abs in vitro were induced by the N-terminal peptide. Up-regulation of the three C-C chemokines and down-modulation of cell surface CCR5 were elicited by the second loop, N-terminal, and first loop peptides. The data suggest that a dual mechanism of C-C chemokines and specific Abs may engage and down-modulate the CCR5 coreceptors and prevent in vitro HIV or SIV replication.
The Role of T Cell Subsets and Cytokines in the Pathogenesis ofHelicobacter pyloriGastritis in Mice
Authors: Eaton Kathryn A. , Mefford Megan , Thevenot Tracy 
Published: April 2014

AbstractGastritis due to Helicobacter pylori in mice and humans is considered a Th1-mediated disease, but the specific cell subsets and cytokines involved are still not well understood. The goal of this study was to investigate the immunopathogenesis of H. pylori-induced gastritis and delayed-type hypersensitivity (DTH) in mice. C57BL/6-Prkdcscid mice were infected with H. pylori and reconstituted with CD4+, CD4-depleted, CD4+CD45RBhigh, or CD4+CD45RBlow splenocytes from wild-type C57BL/6 mice or with splenocytes from C57BL/6IFN-γ−/− or C57BL/6IL-10−/− mice. Four or eight weeks after transfer, DTH to H. pylori Ags was determined by footpad injection; gastritis and bacterial colonization were quantified; and IFN-γ secretion by splenocytes in response to H. pylori Ag was determined. Gastritis and DTH were present in recipients of unfractionated splenocytes, CD4+ splenocytes, and CD4+CD45RBhigh splenocytes, but absent in the other groups. IFN-γ secretion in response to H. pylori Ags was correlated with gastritis, although splenocytes from all groups of mice secreted some IFN-γ. Gastritis was most severe in recipients of splenocytes from IL-10-deficient mice, and least severe in those given IFN-γ-deficient splenocytes. Bacterial colonization in all groups was inversely correlated with gastritis. These data indicate that 1) CD4+ T cells are both necessary and sufficient for gastritis and DTH due to H. pylori in mice; 2) high expression of CD45RB is a marker for gastritis-inducing CD4+ cells; and 3) IFN-γ contributes to gastritis and IL-10 suppresses it, but IFN-γ secretion alone is not sufficient to induce gastritis. The results support the assertion that H. pylori is mediated by a Th1-biased cellular immune response.
A Filarial Nematode-Secreted Phosphorylcholine-Containing Glycoprotein Uncouples the B Cell Antigen Receptor from Extracellular Signal-Regulated Kinase-Mitogen-Activated Protein Kinase by Promoting the Surface Ig-Mediated Recruitment of Src Homology 2 Domain-Containing Tyrosine Phosphatase-1 and Pac-1 Mitogen-Activated Kinase-Phosphatase
Authors: Deehan Maureen R. , Harnett William , Harnett Margaret M. 
Published: April 2014

AbstractUnraveling the molecular mechanisms by which filarial nematodes, major human pathogens in the tropics, evade the host immune system remains an elusive goal. We have previously shown that excretory-secretory product-62 (ES-62), a homologue of phosphorylcholine-containing molecules that are secreted by human parasites and which is active in rodent models of filarial infection, is able to polyclonally activate certain protein tyrosine kinase and mitogen-activating protein kinase signal transduction elements in B lymphocytes. Such activation mediates desensitization of subsequent B cell Ag receptor (BCR) ligation-induced activation of extracellular signal-regulated kinase-mitogen-activated protein (ErkMAP) kinase and ultimately B cell proliferation. We now show that the desensitization is due to ES-62 targeting two major regulatory sites of B cell activation. Firstly, pre-exposure to ES-62 primes subsequent BCR-mediated recruitment of SHP-1 tyrosine phosphatase to abolish recruitment of the RasErkMAP kinase cascade via the Igαβ-ShcGrb2Sos adaptor complex interactions. Secondly, any ongoing ErkMAP kinase signaling in ES-62-primed B cells is terminated by the MAP kinase phosphatase, Pac-1 that is activated consequently to challenge via the BCR.
Cytosolic Phospholipase A2 Participates with TNF-α in the Induction of Apoptosis of Human Macrophages Infected withMycobacterium tuberculosisH37Ra
Authors: Duan Lei , Gan Huixian , Arm Jonathan , Remold Heinz G. 
Published: April 2014

AbstractMacrophage (MΦ) apoptosis, an important innate microbial defense mechanism induced by Mycobacterium tuberculosis (Mtb) H37Ra, depends on the induction of TNF-α synthesis. When protein synthesis is blocked, both infection with Mtb and addition of TNF-α are required to induce caspase 9 activation, caspase 3 activation and apoptosis. In this study, we show that the second protein synthesis-independent signal involves activation of group IV cytosolic phospholipase A2 (cPLA2). Apoptosis of Mtb-infected MΦ and concomitant arachidonic acid release are abrogated by group IV cPLA2 inhibitors (methyl arachidonyl fluorophosphate and methyl trifluoromethyl ketone), but not by inhibitors of group VI Ca2+-independent (iPLA2 ; bromoenol lactone) or of secretory low molecular mass PLA2. In MΦ homogenates, the predominant PLA2 activity showed the same inhibitor sensitivity pattern and preferred arachidonic acid over palmitic acid in substrates, also indicating the presence of one or more group IV cPLA2 enzymes. In concordance with these findings, MΦ lysates contained transcripts and protein for group IV cPLA2-α and cPLA2-γ. Importantly, group IV cPLA2 inhibitors significantly reduced MΦ antimycobacterial activity and addition of arachidonic acid, the major product of group IV cPLA2, to infected MΦ treated with cPLA2 inhibitors completely restored the antimycobacterial activity. Importantly, addition of arachidonic acid alone to infected MΦ significantly reduced the mycobacterial burden. These findings indicate that Mtb induces MΦ apoptosis by independent signaling through at least two pathways, TNF-α and cPLA2, which are both also critical for antimycobacterial defense of the MΦ .
Mannosylated Lipoarabinomannans Inhibit IL-12 Production by Human Dendritic Cells: Evidence for a Negative Signal Delivered Through the Mannose Receptor
Authors: Nigou Jérôme , Zelle-Rieser Claudia , Gilleron Martine , Thurnher Martin , Puzo Germain 
Published: April 2014

AbstractIL-12 is a key cytokine in directing the development of type 1 Th cells, which are critical to eradicate intracellular pathogens such as Mycobacterium tuberculosis. Here, we report that mannose-capped lipoarabinomannans (ManLAMs) from Mycobacterium bovis bacillus Calmette-Guérin and Mycobacterium tuberculosis inhibited, in a dose-dependant manner, the LPS-induced IL-12 production by human dendritic cells. The inhibitory activity was abolished by the loss of the mannose caps or the GPI acyl residues. Mannan, which is a ligand for the mannose receptor (MR) as well as an mAb specific for the MR, also inhibited the LPS-induced IL-12 production by dendritic cells. Our results indicate that ManLAMs may act as virulence factors that contribute to the persistence of M. bovis bacillus Calmette-Guérin and M. tuberculosis within phagocytic cells by suppressing IL-12 responses. Our data also suggest that engagement of the MR by ManLAMs delivers a negative signal that interferes with the LPS-induced positive signals delivered by the Toll-like receptors.
Cooperative Regulation of Mcl-1 by Janus Kinase/STAT and Phosphatidylinositol 3-Kinase Contribute to Granulocyte-Macrophage Colony-Stimulating Factor-Delayed Apoptosis in Human Neutrophils
Authors: Epling-Burnette P. K. , Zhong Bin , Bai Fanqi , Jiang Kun , Bailey Ratna D. , Garcia Roy , Jove Richard , Djeu Julie Y. , Loughran Thomas P. , Wei Sheng 
Published: April 2014

Abstract
Polymorphonuclear neutrophils (PMN) are phagocytic cells constitutively programmed for apoptotic cell death. Exposure to GM-CSF delays apoptosis as measured by annexin-V staining and cell morphological change. We found that STAT5B, STAT1, and STAT3 DNA-binding activity was induced by GM-CSF. We also detected activation of the phosphatidylinositol 3-kinase (PI 3-kinase) pathway after GM-CSF treatment which was inhibited by treatment with the PI 3-kinase inhibitors, wortmannin and LY294002. We investigated whether STAT or PI 3-kinase activity was necessary for the pro-survival response of GM-CSF in PMN. Exposure of PMN to GM-CSF in the presence of either AG-490, antisense STAT3 oligonucleotides, or wortmannin resulted in a partial inhibition of GM-CSF-mediated pro-survival activity. GM-CSF induced a time-dependent increase in the mRNA and protein expression of the anti-apoptotic Bcl-2-family protein, Mcl-1. We examined the hypothesis that Janus kinase/STAT and PI 3-kinase regulation of Mcl-1 contributed to GM-CSF-delayed apoptosis. Using either AG-490 or wortmannin alone, we observed a dose-dependent inhibition of GM-CSF-induced Mcl-1 expression. Using suboptimal doses of AG-490 and wortmannin, we found that both drugs together had an additive effect on delayed apoptosis and Mcl-1 expression. These data suggest that cooperative regulation of Mcl-1 by the Janus kinase/STAT and PI 3-kinase pathways contribute to GM-CSF-delayed apoptosis.
Antibody-Mediated Phagocytosis of the Amyloid β-Peptide in Microglia Is Differentially Modulated by C1q
Authors: Webster Scott D. , Galvan Manuel D. , Ferran Erick , Garzon-Rodriguez William , Glabe Charles G. , Tenner Andrea J. 
Published: April 2014

AbstractMicroglial ingestion of the amyloid β-peptide (Aβ) has been viewed as a therapeutic target in Alzheimer’s disease, in that approaches that enhance clearance of Aβ relative to its production are predicted to result in decreased senile plaque formation, a proposed contributor to neuropathology. In vitro, scavenger receptors mediate ingestion of fibrillar Aβ (fAβ) by microglia. However, the finding that cerebral amyloid deposition in a transgenic mouse model of Alzheimer’s disease was diminished by inoculation with synthetic Aβ has suggested a possible therapeutic role for anti-Aβ Ab-mediated phagocytosis. Microglia also express C1qRP, a receptor for complement protein C1q, ligation of which in vitro enhances phagocytosis of immune complexes formed with IgG levels below that required for optimal FcR-mediated phagocytosis. The data presented here demonstrate FcR-dependent ingestion of Aβ-anti-Aβ complexes (IgG-fAβ) by microglia that is a function of the amount of Ab used to form immune complexes. In addition, C1q incorporated into IgG-fAβ enhanced microglial uptake of these complexes when they contained suboptimal levels of anti-Aβ Ab. Mannose binding lectin and lung surfactant protein A, other ligands of C1qRP, also enhanced ingestion of suboptimally opsonized IgG-fAβ, whereas control proteins did not. Our data suggest that C1qRP-mediated events may promote efficient ingestion of Aβ at low Ab titers, and this may be beneficial in paradigms that seek to clear amyloid via FcR-mediated mechanisms by minimizing the potential for destructive Ab-induced complement-mediated processes.
IL-12 Suppression During Experimental Endotoxin Tolerance: Dendritic Cell Loss and Macrophage Hyporesponsiveness
Authors: Wysocka Maria , Robertson Susan , Riemann Helge , Caamano Jorge , Hunter Christopher , Mackiewicz Agnieszka , Montaner Luis J. , Trinchieri Giorgio , Karp Christopher L. 
Published: April 2014

AbstractEndotoxin tolerance, the transient, secondary down-regulation of a subset of endotoxin-driven responses after exposure to bacterial products, is thought to be an adaptive response providing protection from pathological hyperactivation of the innate immune system during bacterial infection. However, although protecting from the development of sepsis, endotoxin tolerance also can lead to fatal blunting of immunological responses to subsequent infections in survivors of septic shock. Despite considerable experimental effort aimed at characterizing the molecular mechanisms responsible for a variety of endotoxin tolerance-related phenomena, no consensus has been achieved yet. IL-12 is a macrophage- and dendritic cell (DC)-derived cytokine that plays a key role in pathological responses to endotoxin as well as in the induction of protective responses to pathogens. It recently has been shown that IL-12 production is suppressed in endotoxin tolerance, providing a likely partial mechanism for the increased risk of secondary infections in sepsis survivors. We examined the development of IL-12 suppression during endotoxin tolerance in mice. Decreased IL-12 production in vivo is clearly multifactorial, involving both loss of CD11chigh DCs as well as alterations in the responsiveness of macrophages and remaining splenic DCs. We find no demonstrable mechanistic role for B or T lymphocytes, the soluble mediators IL-10, TNF-α, IFN-αβ, or nitric oxide, or the NF-κB family members p50, p52, or RelB.
Surfactant Protein D Regulates NF-κB and Matrix Metalloproteinase Production in Alveolar Macrophages via Oxidant-Sensitive Pathways
Authors: Yoshida Mitsuhiro , Korfhagen Thomas R. , Whitsett Jeffrey A. 
Published: April 2014

Abstract
Targeted ablation of the surfactant protein D (SP-D) gene caused progressive pulmonary emphysema associated with pulmonary infiltration by foamy alveolar macrophages (AMs), increased hydrogen peroxide production, and matrix metalloproteinase (MMP)-2, -9, and -12 expression. In the present study, the mechanisms by which SP-D influences macrophage MMP activity were assessed in AMs from SP-D−/− mice. Tissue lipid peroxides and reactive carbonyls were increased in lungs of SP-D−/− mice, indicating oxidative stress. Immunohistochemical staining of AMs from SP-D−/− mice demonstrated that NF-κB was highly expressed and translocated to the nucleus. Increased NF-κB binding was detected by EMSA in nuclear extracts of AMs isolated from SP-D−/− mice. Antioxidants N-acetylcysteine and pyrrolidine dithiocarbamate inhibited MMP production by AMs from SP-D−/− mice. To assess whether increased oxidant production influenced NF-κB activation and production of MMP-2 and -9, AMs from SP-D−/− mice were treated with the NADPH oxidase inhibitors diphenylene iodonium chloride and apocynin. Inhibition of NADPH oxidase suppressed NF-κB binding by nuclear extracts and decreased production of MMP-2 and 9 in AMs from SP-D−/− mice. SN-50, a synthetic NF-κB-inhibitory peptide, decreased MMP production by AMs from SP-D−/− mice. Oxidant production and reactive oxygen species were increased in lungs of SP-D−/− mice, in turn activating NF-κB and MMP expression. SP-D plays an unexpected inhibitory role in the regulation of NF-κB in AMs.
A CD2-Green Fluorescence Protein-Transgenic Mouse Reveals Very Late Antigen-4-Dependent CD8+ Lymphocyte Rolling in Inflamed Venules
Authors: Singbartl Kai , Thatte Jayant , Smith Michael L. , Wethmar Klaus , Day Kathy , Ley Klaus 
Published: April 2014

AbstractIntravital microscopy allows detailed analysis of leukocyte trafficking in vivo, but fails to identify the nature of leukocytes investigated. Here, we describe the development of a CD2-enhanced green fluorescence protein (EGFP)-transgenic mouse to characterize lymphocyte trafficking during inflammation in vivo. A CD2-EGFP plasmid construct including the CD2 promoter, the EGFP transgene, and the CD2 locus control region was injected into B6CBA/F1 pronuclei. EGFP+ offspring were backcrossed into C57BL/6 mice for six generations. Flow cytometry demonstrated that all peripheral blood EGFP+ cells were positive for CD2 and negative for the granulocyte Ag Ly 6-G (GR-1). EGFPhigh cells stained positive for CD2, CD3, CD8, TCR β-chain, and NK1.1 but did not express the B cell and monocyte markers CD45RA, CD19, and CD11b. In vitro stimulation assays revealed no difference in lymphocyte proliferation and IL-2 secretion between EGFP+ and EGFP− mice. Intravital microscopy of untreated or TNF-α-treated cremaster muscle venules showed EGFP+ cells in vivo, but these cells did not roll or adhere to the vessel wall. In cremaster muscle venules treated with both TNF-α and IFN-γ, EGFPhigh cells rolled, adhered, and transmigrated at a rolling velocity slightly higher (11 μm/s) than that of neutrophils (10 μm/s). Blocking α4 integrin with a mAb increased rolling velocity to 24 μm/s. These findings show that CD8+ T cells roll in TNF-α/IFN-γ-pretreated vessels in vivo via an α4 integrin-dependent pathway.
Minocycline Provides Neuroprotection AgainstN-Methyl-d-aspartate Neurotoxicity by Inhibiting Microglia
Authors: Tikka Tiina M. , Koistinaho Jari E. 
Published: April 2014

AbstractGlutamate excitotoxicity to a large extent is mediated through activation of the N-methyl-d-aspartate (NMDA)-gated ion channels in several neurodegenerative diseases and ischemic stroke. Minocycline, a tetracycline derivative with antiinflammatory effects, inhibits IL-1β-converting enzyme and inducible nitric oxide synthase up-regulation in animal models of ischemic stroke and Huntington’s disease and is therapeutic in these disease animal models. Here we report that nanomolar concentrations of minocycline protect neurons in mixed spinal cord cultures against NMDA excitotoxicity. NMDA treatment alone induced microglial proliferation, which preceded neuronal death, and administration of extra microglial cells on top of these cultures enhanced the NMDA neurotoxicity. Minocycline inhibited all these responses to NMDA. Minocycline also prevented the NMDA-induced proliferation of microglial cells and the increased release of IL-1β and nitric oxide in pure microglia cultures. Finally, minocycline inhibited the NMDA-induced activation of p38 mitogen-activated protein kinase (MAPK) in microglial cells, and a specific p38 MAPK inhibitor, but not a p44/42 MAPK inhibitor, reduced the NMDA toxicity. Together, these results suggest that microglial activation contributes to NMDA excitotoxicity and that minocycline, a tetracycline derivative, represents a potential therapeutic agent for brain diseases.
Blockade of α5β1 Integrins Reverses the Inhibitory Effect of Tenascin on Chemotaxis of Human Monocytes and Polymorphonuclear Leukocytes Through Three-Dimensional Gels of Extracellular Matrix Proteins
Authors: Loike John D. , Cao Long , Budhu Sadna , Hoffman Stanley , Silverstein Samuel C. 
Published: April 2014

Abstract
Tenascin is an extracellular matrix protein found in adults in T cell-dependent areas of lymphoid tissues, sites of inflammation, and tumors. We report here that it inhibited chemotaxis of chemoattractant-stimulated human monocytes and chemoattractant-stimulated polymorphonuclear leukocytes (PMN) through three-dimensional gels composed of collagen I or Matrigel, and chemotaxis of leukotriene B4-stimulated PMN through fibrin gels. The inhibitory effect of tenascin on monocyte or PMN chemotaxis through these matrices was reversed by Abs directed against α5β1 integrins or by a peptide (GRGDSP) that binds to β1 integrins. Tenascin did not affect leukotriene B4- or fMLP-stimulated expression of β1 or β2 integrins, but did exert a small inhibitory effect on PMN adhesion and closeness of apposition to fibrin(ogen)-containing surfaces. Thus, α5β1 integrins mediate the inhibitory effect of tenascin on monocyte and PMN chemotaxis, without promoting close apposition between these leukocytes and surfaces coated with tenascin alone or with tenascin bound to other matrix proteins. This contrasts with the role played by α5β1 integrins in promoting close apposition between fMLP-stimulated PMN and fibrin containing surfaces, thereby inhibiting chemotaxis of fMLP-stimulated PMN through fibrin gels. Thus, chemoattractants and matrix proteins regulate chemotaxis of phagocytic leukocytes by at least two different mechanisms: one in which specific chemoattractants promote very tight adhesion of leukocytes to specific matrix proteins and another in which specific matrix proteins signal cessation of migration without markedly affecting strength of leukocyte adhesion.
Hypoxia-Inducible Factor 1-Mediated Inhibition of Peroxisome Proliferator-Activated Receptor α Expression During Hypoxia
Authors: Narravula Sailaja , Colgan Sean P. 
Published: April 2014

Abstract
Peroxisome proliferator-activated receptors (PPARs) are nuclear hormone-binding proteins that regulate transcriptional responses to peroxisome proliferators and structurally diverse fatty acids. PPARs have been implicated in a wide variety of functions, including lipid homeostasis and inflammatory responses. In this study, we examined the expression of PPAR-α in response to ambient hypoxia. Initial studies using microarray analysis of intestinal epithelial mRNA revealed that hypoxia rapidly down-regulates PPAR-α mRNA and protein in epithelial cells in vitro and in vivo. Subsequent studies revealed that the PPAR-α gene bears a DNA consensus motif for the transcription factor hypoxia-inducible factor 1 (HIF-1). EMSA analysis revealed that ambient hypoxia induces HIF-1α binding to the HIF-1 consensus domain of PPAR-α in parallel to HIF-1 nuclear accumulation, and antisense depletion of HIF-1α resulted in a loss of PPAR-α down-regulation. The PPAR-α ligand pirinixic acid (WY14643) functionally promoted IFN-γ-induced ICAM-1 expression in normoxic epithelia, and this response was lost in cells pre-exposed to ambient hypoxia. Such results indicate that HIF-1-dependent down-regulation of PPAR-α may provide an adaptive response to proinflammatory stimuli during cellular hypoxia. These studies provide unique insight into the regulation of PPAR-α expression and, importantly, provide an example of a down-regulatory pathway mediated by HIF-1.