bluuebunny/crossref_metadata_2025_split huggingface dataset:
Differential Roles of CC Chemokine Ligand 2/Monocyte Chemotactic Protein-1 and CCR2 in the Development of T1 Immunity
Authors: Traynor Tim R. , Herring Amy C. , Dorf Martin E. , Kuziel William A. , Toews Galen B. , Huffnagle Gary B. 
Published: April 2014

AbstractCCR2 and its major ligand, chemokine ligand 2 (CCL2)/monocyte chemotactic protein-1, have been found to influence T1/T2 immune response polarization. Our objective was to directly compare the roles of CCR2 and CCL2 in T1/T2 immune response polarization using a model of pulmonary Cryptococcus neoformans infection. Either deletion of CCR2 or treatment of wild-type mice with CCL2 neutralizing Ab produced significant and comparable reductions in macrophage and T cell recruitment into the lungs following infection. Both CCL2 neutralization and CCR2 deficiency resulted in significantly diminished IFN-γ production, and increased IL-4 and IL-5 production by lung leukocytes (T1 to T2 switch), but only CCR2 deficiency promoted pulmonary eotaxin production and eosinophilia. In the lung-associated lymph nodes (LALN), CCL2-neutralized mice developed Ag-specific IFN-γ-producing cells, while CCR2 knockout mice did not. LALN from CCR2 knockout mice also had fewer MHCII+CD11c+ and MHCII+CD11b+ cells, and produced significantly less IL-12p70 and TNF-α when stimulated with heat-killed yeast than LALN from wild-type or CCL2-neutralized mice, consistent with a defect in APC trafficking in CCR2 knockout mice. Neutralization of CCL2 in CCR2 knockout mice did not alter immune response development, demonstrating that the high levels of CCL2 in these mice did not play a role in T2 polarization. Therefore, CCR2 (but not CCL2) is required for afferent T1 development in the lymph nodes. In the absence of CCL2, T1 cells polarize in the LALN, but do not traffic from the lymph nodes to the lungs, resulting in a pulmonary T2 response.
Mitogen-Activated Protein Kinase-Activated Protein Kinase 2-Deficient Mice Show Increased Susceptibility to Listeria monocytogenes Infection
Authors: Lehner Martin D. , Schwoebel Frank , Kotlyarov Alexey , Leist Marcel , Gaestel Matthias , Hartung Thomas 
Published: April 2014

Abstract
Mitogen-activated protein kinase-activated protein kinase 2 (MK2) is one of several kinases activated through direct phosphorylation by p38 mitogen-activated protein kinase. MK2 regulates LPS-induced TNF mRNA translation, and targeted mutation of the MK2 gene renders mice more resistant to d-galactosamine plus LPS-induced liver damage. In the present study, we investigated the role of MK2 in immune defense against Listeria monocytogenes infection. MK2-deficient mice displayed diminished resistance to L. monocytogenes due to impaired control of bacterial growth. The increase in bacterial load in MK2−/− mice was associated with normal levels of IL-1β, IL-6, and IFN-γ, whereas TNF production was strongly attenuated. In line, MK2-deficient bone marrow-derived macrophages showed impaired release of TNF, but not of IL-1β, in response to various bacterial stimuli in addition to decreased phagocytosis of fluorescence-labeled bacteria. Furthermore, spleen cells from MK2−/− mice displayed diminished IFN-γ synthesis after stimulation with L. monocytogenes. In contrast, MK2 deficiency had no effect on macrophage generation of NO or on oxidative burst activity in response to L. moocytogenes. These results indicate an essential role of MK2 in host defense against intracellular bacteria probably via regulation of TNF and IFN-γ production required for activation of antibacterial effector mechanisms.
The Role of IL-18 in Blood-Stage Immunity Against Murine MalariaPlasmodium yoelii 265andPlasmodium berghei ANKA
Authors: Singh Ram Pyare , Kashiwamura Shin-ichiro , Rao Prakash , Okamura Haruki , Mukherjee Askok , Chauhan Virander Singh 
Published: April 2014

AbstractA possible protective role of IL-18 in host defense against blood-stage murine malarial infection was studied in BALB/c mice using a nonlethal strain, Plasmodium yoelii 265, and a lethal strain, Plasmodium berghei ANKA. Infection induced an increase in mRNA expression of IL-18, IL-12p40, IFN-γ, and TNF-α in the case of P. yoelii 265 and an increase of IL-18, IL-12p40, and IFN-γ in the case of P. berghei ANKA. The timing of mRNA expression of IL-18 in both cases was consistent with a role in the induction of IFN-γ protein expression. Histological examination of spleen and liver tissues from infected controls treated with PBS showed poor cellular inflammatory reaction, massive necrosis, a large number of infected parasitized RBCs, and severe deposition of hemozoin pigment. In contrast, IL-18-treated infected mice showed massive infiltration of inflammatory cells consisting of mononuclear cells and Kupffer cells, decreased necrosis, and decreased deposition of the pigment hemozoin. Treatment with rIL-18 increased serum IFN-γ levels in mice infected with both parasites, delayed onset of parasitemia, conferred a protective effect, and thus increased survival rate of infected mice. Administration of neutralizing anti-IL-18 Ab exacerbated infection, impaired host resistance and shortened the mean survival of mice infected with P. berghei ANKA. Furthermore, IL-18 knockout mice were more susceptible to P. berghei ANKA than were wild-type C57BL/6 mice. These data suggest that IL-18 plays a protective role in host defense by enhancing IFN-γ production during blood-stage infection by murine malaria.
The Adapter Molecule Gab2 Regulates FcεRI-Mediated Signal Transduction in Mast Cells
Authors: Xie Zhi-Hui , Ambudkar Indu , Siraganian Reuben P. 
Published: April 2014

Abstract
The recently cloned scaffolding molecule Gab2 can assemble multiple molecules involved in signaling pathways. Bone marrow-derived mast cells isolated from Gab2−/− mice have defective signaling probably due to the lack of the activation of phosphatidylinositol-3 kinase (PI3-kinase). In this study, we investigated the role of Gab2 using the rat basophilic leukemia 2H3 cell line mast cells. FcεRI aggregation induced the tyrosine phosphorylation of Gab2 and translocation of a significant fraction of it from the cytosol to the plasma membrane. As in other cells, Gab2 was found to associate with several signaling molecules including Src homology 2-containing protein tyrosine phosphatase 2, Grb2, Lyn, and phospholipase Cγ (PLCγ). The association of Gab2 with Lyn and PLCγ were enhanced after receptor aggregation. Overexpression of Gab2 in rat basophilic leukemia 2H3 cell line cells inhibited the FcεRI-induced tyrosine phosphorylation of the subunits of the receptor, and the phosphorylation and/or activation of Syk and mitogen-activated protein kinase. Downstream events such as calcium mobilization, degranulation, and induction of TNF-α and IL-6 gene transcripts were decreased in Gab2 overexpressing cells, although Akt phosphorylation as a measure of PI3-kinase activation was unaffected. These results suggest that in addition to the positive effects mediated by PI3-kinase that are apparent in Gab2−/− mast cells, Gab2 by interacting with Lyn and PLCγ may have negative regulatory effects on FcεRI-induced mast cell signaling and functions.
Helicobacter pylori Induces Macrophage Apoptosis by Activation of Arginase II
Authors: Gobert Alain P. , Cheng Yulan , Wang Jian-Ying , Boucher Jean-Luc , Iyer Ramaswamy K. , Cederbaum Stephen D. , Casero Robert A. , Newton Jamie C. , Wilson Keith T. 
Published: April 2014

Abstract
Helicobacter pylori infection induces innate immune responses in macrophages, contributing to mucosal inflammation and damage. Macrophage apoptosis is important in the pathogenesis of mucosal infections but has not been studied with H. pylori. NO derived from inducible NO synthase (iNOS) can activate macrophage apoptosis. Arginase competes with iNOS by converting l-arginine to l-ornithine. Since we reported that H. pylori induces iNOS in macrophages, we now determined whether this bacterium induces arginase and the effect of this activation on apoptosis. NF-κB-dependent induction of arginase II, but not arginase I, was observed in RAW 264.7 macrophages cocultured with H. pylori. The time course of apoptosis matched those of both arginase and iNOS activities. Surprisingly, apoptosis was blocked by the arginase inhibitors Nω-hydroxy-l-arginine or Nω-hydroxy-nor-l-arginine, but not by the iNOS inhibitor N-iminoethyl-l-lysine. These findings were confirmed in peritoneal macrophages from iNOS-deficient mice and were not dependent on bacterial-macrophage contact. Ornithine decarboxylase (ODC), which metabolizes l-ornithine to polyamines, was also induced in H. pylori-stimulated macrophages. Apoptosis was abolished by inhibition of ODC and was restored by the polyamines spermidine and spermine. We also demonstrate that arginase II expression is up-regulated in both murine and human H. pylori gastritis tissues, indicating the likely in vivo relevance of our findings. Therefore, we describe arginase- and ODC-dependent macrophage apoptosis, which implicates polyamines in the pathophysiology of H. pylori infection.
Toll-Like Receptor (TLR)2 and TLR4 in Human Peripheral Blood Granulocytes: A Critical Role for Monocytes in Leukocyte Lipopolysaccharide Responses
Authors: Sabroe Ian , Jones Elizabeth C. , Usher Lynne R. , Whyte Moira K. B. , Dower Steven K. 
Published: April 2014

Abstract
Leukocyte responsiveness to LPS is dependent upon CD14 and receptors of the Toll-like receptor (TLR) family. Neutrophils respond to LPS, but conflicting data exist regarding LPS responses of eosinophils and basophils, and expression of TLRs at the protein level in these granulocyte lineages has not been fully described. We examined the expression of TLR2, TLR4, and CD14 and found that monocytes expressed relatively high levels of cell surface TLR2, TLR4, and CD14, while neutrophils also expressed all three molecules, but at low levels. In contrast, basophils expressed TLR2 and TLR4 but not CD14, while eosinophils expressed none of these proteins. Tested in a range of functional assays including L-selectin shedding, CD11b up-regulation, IL-8 mRNA generation, and cell survival, neutrophils responded to LPS, but eosinophils and basophils did not. In contrast to previous data, we found, using monocyte depletion by negative magnetic selection, that neutrophil responses to LPS were heavily dependent upon the presence of a very low level of monocytes, and neutrophil survival induced by LPS at 22 h was monocyte dependent. We conclude that LPS has little role in the regulation of peripheral blood eosinophil and basophil function, and that, even in neutrophils, monocytes orchestrate many previously observed leukocyte LPS response patterns.
Role of Mitogen-Activated Protein Kinases in CpG DNA-Mediated IL-10 and IL-12 Production: Central Role of Extracellular Signal-Regulated Kinase in the Negative Feedback Loop of the CpG DNA-Mediated Th1 Response
Authors: Yi Ae-Kyung , Yoon Jae-Geun , Yeo Seon-Ju , Hong Soon-Cheol , English B. Keith , Krieg Arthur M. 
Published: April 2014

AbstractThe mitogen-activated protein kinases, extracellular signal-regulated kinase (ERK), and p38, are activated in response to infectious agents and innate immune stimulators such as CpG DNA, and regulate the subsequent initiation and termination of immune responses. CpG DNA activates p38 and ERK with slightly different kinetics in monocytic cells. The present studies investigated the roles of these two key mitogen-activated protein kinases in regulating the CpG DNA-induced production of pro- and anti-inflammatory cytokines in the macrophage-like cell line RAW264.7. p38 activity was essential for the induction of both IL-10 and IL-12 expression by CpG DNA. In contrast, CpG DNA-mediated ERK activation was shown to suppress IL-12 production, but to be essential for the CpG DNA-induced IL-10 production. Studies using rIL-10 and IL-10 gene-deficient mice demonstrated that the inhibitory effect of ERK on CpG DNA-mediated IL-12 production is indirect, due to the role of ERK in mediating IL-10 production. These results demonstrate that ERK and p38 differentially regulate the production of pro- and anti-inflammatory cytokines in APCs that have been activated by CpG DNA. CpG DNA-induced p38 activity is required for the resulting innate immune activation. In contrast, ERK plays a central negative regulatory role in the CpG DNA-mediated Th1 type response by promoting production of the Th2 type cytokine, IL-10.
Endotoxin-Stimulated Nitric Oxide Production Inhibits Expression of Cytochrome c Oxidase in ANA-1 Murine Macrophages
Authors: Wei Junping , Guo Hongtao , Kuo Paul C. 
Published: April 2014

Abstract
In endotoxin (LPS)-mediated states of sepsis, inducible NO synthase expression and NO production are associated with molecular regulatory functions that determine the host inflammatory response. NO inhibits cellular respiration and mitochondrial electron transport by inhibition of cytochrome c oxidase (CcO) activity. CcO is the terminal complex of the mitochondrial respiratory chain, responsible for 90% of cellular oxygen consumption and essential for cellular energy production. Subunit 1 (CcO I) is considered to be the most critical of the 13 CcO component subunits. In this regard little is known of the effect of NO on the transcriptional program for CcO expression. In ANA-1 murine macrophages, LPS-mediated NO synthesis decreases CcO enzyme activity, CcO I protein expression, and CcO I steady mRNA levels. Mitochondrial run-on analysis demonstrates unaltered CcO I mitochondrial gene transcription. Half-life analysis indicates that CcO I mRNA stability is significantly decreased in the presence of LPS-mediated NO synthesis. In this study using LPS-stimulated ANA-1 murine macrophages, we demonstrate that expression of the mitochondrial gene product, CcO I, is significantly decreased as the result of a unique and previously uncharacterized, NO-dependent post-transcriptional regulatory mechanism.
Leukocyte-Endothelial Cell Interactions Are Enhanced in Dermal Postcapillary Venules of MRL/faslpr(Lupus-Prone) Mice: Roles of P- and E-Selectin
Authors: Hickey Michael J. , Bullard Daniel C. , Issekutz Andrew , James Will G. 
Published: April 2014

AbstractMRL/faslpr mice are affected by a systemic autoimmune disease that results in widespread leukocytic infiltration of the vasculature, including in the skin. The molecular pathways responsible for this leukocyte recruitment are poorly understood. Therefore, the aim of these experiments was to examine the mechanisms of leukocyte trafficking in the dermal microvasculature of MRL/faslpr mice. Intravital microscopy was used to examine leukocyte rolling and adhesion in dermal postcapillary venules of MRL/faslpr mice at 8, 12, and 16 wk of age. When compared with age-matched BALB/c and MRL+/+ (nondiseased) mice, leukocyte rolling and adhesion in MRL/faslpr mice were significantly enhanced at 12 wk of age, and remained elevated at 16 wk of age. At 8 and 12 wk, leukocyte rolling in all three strains was almost entirely inhibited by an anti-P-selectin mAb. In contrast, at 16 wk some (∼10%) leukocyte rolling persisted following P-selectin blockade. This residual rolling was predominantly inhibitable with an anti-E-selectin mAb; however, treatment with anti-E-selectin mAb alone had a minimal effect. P-selectin-deficient MRL/faslpr mice also displayed leukocyte rolling that was significantly lower than in wild-type MRL/faslpr mice. However, in these mice, leukocyte adhesion remained at the elevated levels observed in wild-type MRL/faslpr mice. This adhesion was eliminated by chronic treatment with anti-E-selectin mAb. These findings indicate that leukocyte-endothelial cell interactions are enhanced in the dermal microvasculature of MRL/faslpr mice above the age of 12 wk. Furthermore, the data suggest that the endothelial selectins share overlapping roles in mediating this enhanced leukocyte recruitment.
SHIP Negatively Regulates IgE + Antigen-Induced IL-6 Production in Mast Cells by Inhibiting NF-κB Activity
Authors: Kalesnikoff Janet , Baur Nicole , Leitges Michael , Hughes Michael R. , Damen Jacqueline E. , Huber Michael , Krystal Gerald 
Published: April 2014

Abstract
We demonstrate in this study that IgE + Ag-induced proinflammatory cytokine production is substantially higher in Src homology-2-containing inositol 5′-phosphatase (SHIP)−/− than in SHIP+/+ bone marrow-derived mast cells (BMMCs). Focusing on IL-6, we found that the repression of IL-6 mRNA and protein production in SHIP+/+ BMMCs requires the enzymatic activity of SHIP, because SHIP−/− BMMCs expressing wild-type, but not phosphatase-deficient (D675G), SHIP revert the IgE + Ag-induced increase in IL-6 mRNA and protein down to levels seen in SHIP+/+ BMMCs. Comparing the activation of various signaling pathways to determine which ones might be responsible for the elevated IL-6 production in SHIP−/− BMMCs, we found the phosphatidylinositol 3-kinase/protein kinase B (PKB), extracellular signal-related kinase (Erk), p38, c-Jun N-terminal kinase, and protein kinase C (PKC) pathways are all elevated in IgE + Ag-induced SHIP−/− cells. Moreover, inhibitor studies suggested that all these pathways play an essential role in IL-6 production. Looking downstream, we found that IgE + Ag-induced IL-6 production is dependent on the activity of NF-κB and that IκB phosphorylation/degradation and NF-κB translocation, DNA binding and transactivation are much higher in SHIP−/− BMMCs. Interestingly, using various pathway inhibitors, it appears that the phosphatidylinositol 3-kinase/PKB and PKC pathways elevate IL-6 mRNA synthesis, at least in part, by enhancing the phosphorylation of IκB and NF-κB DNA binding while the Erk and p38 pathways enhance IL-6 mRNA synthesis by increasing the transactivation potential of NF-κB. Taken together, our data are consistent with a model in which SHIP negatively regulates NF-κB activity and IL-6 synthesis by reducing IgE + Ag-induced phosphatidylinositol-3,4,5-trisphosphate levels and thus PKB, PKC, Erk, and p38 activation.
Selective Inhibition of Cyclooxygenase-2 Expression by 15-Deoxy-Δ12,1412,14-prostaglandin J2 in Activated Human Astrocytes, But Not in Human Brain Macrophages
Authors: Janabi Nazila 
Published: April 2014

Abstract
Overexpression of the inducible cyclooxygenase (COX-2) and inducible NO synthase (iNOS) in activated brain macrophages (microglia) and astrocytes appears central to many neuroinflammatory conditions. 15-Deoxy-Δ12,14-PGJ2 (15d-PGJ2) is a ligand for the peroxisome proliferator-activated receptor (PPAR)γ. It has been proposed as an inhibitor of microglial activation, based on the study of iNOS down-regulation in rodent microglia. Because iNOS induction after cytokine activation remains controversial in human microglia, we examined the effect of 15d-PGJ2 and other PPAR agonists on human microglia and astrocytes, using COX-2 induction as an index of activation. We found that PPARα ligands (clofibrate and WY14643) enhanced IL-1β-induced COX-2 expression in human astrocytes and microglia, while inhibiting IL-1β plus IFN-γ induction of iNOS in astrocytes. This is the first description of an inhibition of iNOS uncoupled from that of COX-2. 15d-PGJ2 suppressed COX-2 induction in human astrocytes. It prevented NF-κB binding to the COX-2 promoter through a new pathway that is the repression of NF-κBp50 induction by IL-1β. In contrast, 15d-PGJ2 increased c-Jun and c-Fos DNA-binding activity in astrocytes, which may result in the activation of other inflammatory pathways. In human microglia, no effect of 15d-PGJ2 on COX-2 and NF-κBp65/p50 induction was observed. However, the entry of 15d-PGJ2 occurred in microglia because STAT-1 and c-Jun expression was modulated. Our data suggest the existence of novel pathways mediated by 15d-PGJ2 in human astrocytes. They also demonstrate that, unlike astrocytes and peripheral macrophages or rodent brain macrophages, human microglia are not subject to the anti-inflammatory effect of 15d-PGJ2 in terms of COX-2 inhibition.
IL-16 Promotes Leukotriene C4 and IL-4 Release from Human Eosinophils via CD4- and Autocrine CCR3-Chemokine-Mediated Signaling
Authors: Bandeira-Melo Christianne , Sugiyama Kumiya , Woods Lesley J. , Phoofolo Mojabeng , Center David M. , Cruikshank William W. , Weller Peter F. 
Published: April 2014

AbstractHuman eosinophils are potential sources of inflammatory and immunomodulatory mediators, including cysteinyl leukotrienes, chemokines, and cytokines, which are pertinent to allergic inflammation. We evaluated the means by which IL-16, a recognized eosinophil chemoattractant, might act on eosinophils to affect their capacity to release leukotriene C4 (LTC4) or their preformed stores of chemokines (eotaxin, RANTES) or Th1 (IL-12) or Th2 (IL-4) cytokines. IL-16 dose dependently (0.01–100 nM) elicited new lipid body formation, intracellular LTC4 formation at lipid bodies, and priming for enhanced calcium ionophore-activated LTC4 release. IL-16 also elicited brefeldin A-inhibitable, vesicular transport-mediated release of preformed IL-4, but not IL-12, from eosinophils. CD4 is a recognized IL-16R, and accordingly anti-CD4 Fab, soluble CD4, and a CD4 domain 4-based IL-16 blocking peptide inhibited the actions of IL-16 on eosinophils. Although CD4 is not G-protein coupled, pertussis toxin inhibited IL-16-induced eosinophil activation. IL-16 actions were found to be mediated by the autocrine activity, not of platelet-activating factor, but rather of endogenous CCR3-acting chemokines. IL-16 induced the rapid vesicular transport-mediated release of RANTES. The effects of IL-16 were blocked by CCR3 inhibitors (met-RANTES, anti-CCR3 mAb) and by neutralizing anti-eotaxin and anti-RANTES mAbs, but not by platelet-activating factor receptor antagonists (CV6209, BN52021). RANTES and eotaxin each enhanced LTC4 and IL-4 (but not IL-12) release. Therefore, IL-16 activation of eosinophils is CD4-mediated to elicit the extracellular release of preformed RANTES and eotaxin, which then in an autocrine fashion act on plasma membrane CCR3 receptors to stimulate both enhanced LTC4 production and the preferential release of IL-4, but not IL-12, from within eosinophils.
IFN-γ, But Not Fas, Mediates Reduction of Allergen-Induced Mucous Cell Metaplasia by Inducing Apoptosis
Authors: O-Quan Shi Zha , Fischer Mark J. , De Sanctis George T. , Schuyler Mark R. , Tesfaigzi Yohannes 
Published: April 2014

AbstractInflammatory responses induced by allergen exposure cause mucous cell metaplasia (MCM) by differentiation of existing and proliferating epithelial cells into mucus-storing cells. Airway epithelia have various mechanisms that resolve these changes to form normal airway epithelia. In this report, we first investigated the state of mucous cell metaplasia and the mechanisms by which MCM is reduced despite continued exposures to allergen. After 5 days of allergen exposure, extensive MCM had developed but was reduced when allergen challenge was continued for 15 days. During this exposure period, IL-13 levels decreased and IFN-γ levels increased in the bronchoalveolar lavage fluid. In contrast, IL-13 levels decreased but IFN-γ was not detected at any time point during the resolution of MCM following cessation of allergen exposure. Instillation of IFN-γ but not anti-Fas caused accelerated resolution of MCM and MCM was not resolved in Stat1-deficient mice exposed to allergen for 15 days, confirming that IFN-γ is crucial for reducing MCM during prolonged exposures to allergen. IFN-γ but not anti-Fas induced apoptotic cell death in proliferating normal human bronchial epithelial cells and in human bronchial epithelial cells from subjects with asthma. The apoptotic effect of IFN-γ was caspase dependent and was inhibited by IL-13, indicating that the Th2 milieu in asthmatics may maintain MCM by preventing cell death in metaplastic mucous cells. These studies could be useful in the understanding of deficiencies leading to chronicity in airway changes and designing novel therapies to reverse MCM and airway obstruction in asthmatics.