bluuebunny/crossref_metadata_2025_split huggingface dataset:
Regulation of Phosphatidylinositol 3-Kinase Activity and Phosphatidylinositol 3,4,5-Trisphosphate Accumulation by Neutrophil Priming Agents
Authors: Cadwallader Karen A. , Condliffe Alison M. , McGregor Alex , Walker Trevor R. , White Jessica F. , Stephens Len R. , Chilvers Edwin R. 
Published: April 2014

Abstract
Neutrophil priming by agents such as TNF-α and GM-CSF causes a dramatic increase in the response of these cells to secretagogue agonists and affects the capacity of neutrophils to induce tissue injury. In view of the central role of phosphatidylinositol 3-kinase (PI3-kinase) in regulating NADPH oxidase activity we examined the influence of priming agents on agonist-stimulated phosphatidylinositol 3,4,5-trisphosphate (PtdIns(3,4,5)P3) accumulation in human neutrophils. Pretreatment of neutrophils with TNF-α or GM-CSF, while not influencing fMLP-stimulated PtdIns(3,4,5)P3 accumulation at 5 s, caused a major increase in PtdIns(3,4,5)P3 at later times (10–60 s), which paralleled the augmented superoxide anion (O2−) response. The intimate relationship between PtdIns(3,4,5)P3 accumulation and O2− release was confirmed using platelet-activating factor, which caused full but transient priming of both responses. Likewise, LY294002, a PI3-kinase inhibitor, and genistein, a tyrosine kinase inhibitor, caused parallel inhibition of O2− generation and PtdIns(3,4,5)P3 accumulation; in contrast, radicicol, which inhibits receptor-mediated activation of p85 PI3-kinase, had no effect on either response. Despite major increases in PI3-kinase activity observed in p85 and anti-phosphotyrosine immunoprecipitates in growth factor-stimulated smooth muscle cells, no such increase was observed in primed/stimulated neutrophils. In contrast, both fMLP and TNF-α alone caused a 3-fold increase in PI3-kinase activity in p110γ PI3-kinase immunoprecipitates. p21ras activation (an upstream regulator of PI3-kinase) was unaffected by priming. These data demonstrate that timing and magnitude of PtdIns(3,4,5)P3 accumulation in neutrophils correlate closely with O2− generation, that PI3-kinase-γ is responsible for the enhanced PtdIns(3,4,5)P3 production seen in primed cells, and that factors other than activation of p21ras underlie this response.
Optimal Colocalization of TCR and CD8 as a Novel Mechanism for the Control of Functional Avidity
Authors: Cawthon Andrew G. , Alexander-Miller Martha A. 
Published: April 2014

AbstractThe improved efficacy of high avidity CTL for clearance of virus has been well-documented. Thus, elucidation of the mechanisms that confer the increased sensitivity to peptide ligand demonstrated by high avidity CTL is critical. Using CTL lines of high and low avidity generated from a TCR transgenic mouse, we have found that functional avidity can be controlled by the expression of CD8αα vs CD8αβ and the ability of CTLs to colocalize the TCR and CD8 in the membrane. Colocalization of these molecules was mediated by lipid rafts and importantly, raft disruption resulted in the conversion of high avidity CTL into a lower functional avidity phenotype. These novel findings provide insights into the control of functional avidity in response to viral infection.
Chronic Exposure to Innocuous Antigen in Sensitized Mice Leads to Suppressed Airway Eosinophilia That Is Reversed by Granulocyte Macrophage Colony-Stimulating Factor
Authors: Swirski Filip K. , Sajic Dusan , Robbins Clinton S. , Gajewska Beata U. , Jordana Manel , Stämpfli Martin R. 
Published: April 2014

AbstractIn this study we investigated the impact of chronic allergen exposure on airway inflammation and humoral responses in sensitized mice. We observed marked eosinophilia in the bronchoalveolar lavage, lung tissue, and peripheral blood after 2 wk of exposure. In contrast, eosinophilia was markedly reduced by 3 wk and completely resolved by 4 wk of exposure, despite the continued presence of Ag. Decreases in airway eosinophilia were associated with a robust humoral response. We observed that levels of OVA-specific IgE, IgG1, and IgG2a increased during the course of exposure. To assess whether continuous exposure to Ag impacts the ability of the lung to respond to subsequent Ag challenge, mice were exposed to either 2 or 4 wk of OVA in the context of GM-CSF. All groups were then rested for 28 days and exposed to OVA on three consecutive days. We observed a significant decrease in airway eosinophilia and IL-5 expression in the bronchoalveolar lavage and serum in mice initially exposed to 4 wk of OVA, compared with animals exposed to 2 wk only. However, in both groups expression of B7.2 on dendritic cells as well as CD25, CD69, and T1/ST2 on CD4+ T cells was enhanced, suggesting immune activation. Delivery of rGM-CSF fully restored airway eosinophilia. This study shows that exposure to innocuous Ag alone does not lead to persistent eosinophilic airway inflammation, but rather to abrogated eosinophilia. This suppression can be reversed by GM-CSF.
Microbial Recognition Via Toll-Like Receptor-Dependent and -Independent Pathways Determines the Cytokine Response of Murine Dendritic Cell Subsets to CD40 Triggering
Authors: Edwards Alexander D. , Manickasingham Shivanthi P. , Spörri Roman , Diebold Sandra S. , Schulz Oliver , Sher Alan , Kaisho Tsuneyasu , Akira Shizuo , Reis e Sousa Caetano 
Published: April 2014

Abstract
Dendritic cells (DC) can produce Th-polarizing cytokines and direct the class of the adaptive immune response. Microbial stimuli, cytokines, chemokines, and T cell-derived signals all have been shown to trigger cytokine synthesis by DC, but it remains unclear whether these signals are functionally equivalent and whether they determine the nature of the cytokine produced or simply initiate a preprogrammed pattern of cytokine production, which may be DC subtype specific. Here, we demonstrate that microbial and T cell-derived stimuli can synergize to induce production of high levels of IL-12 p70 or IL-10 by individual murine DC subsets but that the choice of cytokine is dictated by the microbial pattern recognition receptor engaged. We show that bacterial components such as CpG-containing DNA or extracts from Mycobacterium tuberculosis predispose CD8α+ and CD8α−CD4− DC to make IL-12 p70. In contrast, exposure of CD8α+, CD4+ and CD8α−CD4− DC to heat-killed yeasts leads to production of IL-10. In both cases, secretion of high levels of cytokine requires a second signal from T cells, which can be replaced by CD40 ligand. Consistent with their differential effects on cytokine production, extracts from M. tuberculosis promote IL-12 production primarily via Toll-like receptor 2 and an MyD88-dependent pathway, whereas heat-killed yeasts activate DC via a Toll-like receptor 2-, MyD88-, and Toll/IL-1R domain containing protein-independent pathway. These results show that T cell feedback amplifies innate signals for cytokine production by DC and suggest that pattern recognition rather than ontogeny determines the production of cytokines by individual DC subsets.
Endothelial Cells Stimulate T Cell NFAT Nuclear Translocation in the Presence of Cyclosporin A: Involvement of the wnt/Glycogen Synthase Kinase-3β Pathway
Authors: Murphy Lisa L. Salazar , Hughes Christopher C. W. 
Published: April 2014

Abstract
T cells resistant to the immunosuppressive drug cyclosporin A (CsA) may be important mediators of chronic graft rejection. We previously reported that T cells activated in the presence of endothelial cells (EC) develop resistance to CsA, and initiate IL-2 secretion within 8–12 h of triggering. CsA normally blocks the phosphatase, calcineurin, thus preventing nuclear translocation of the transcription factor, NFAT. We find that in the presence but not the absence of EC, NFAT1 can be detected in the nuclei of CsA-treated T cells within 8 h of triggering, reaching a maximal level of 60% of control by 24 h. Glycogen synthase kinase-3β (GSK-3β), which rephosphorylates NFAT and promotes nuclear export, is inhibited by EC costimulation. GSK-3β is a component of the wnt signaling pathway, and EC express wnt-5a and T cells express frizzled-5, a wnt-5a receptor. Wnt-5a promotes T cell NFAT nuclear accumulation in the presence of CsA, an effect mimicked by Li+, a potent inhibitor of GSK-3β. The protein kinase C agonist PMA dramatically synergizes with both EC and wnt-5a in stimulating T cell IL-2 synthesis, and inhibition of either protein kinase C by Ro-31-8425 or G-proteins by pertussis toxin effectively blocks the actions of wnt-5a on T cells. Finally, a secreted, dominant-negative form of frizzled-5 blocks EC-mediated CsA resistance. Thus, EC promote CsA-resistant nuclear localization of NFAT and subsequent IL-2 synthesis through a noncanonical wnt-dependent pathway.
Molecular Mechanism of the Activation-Induced Cell Death Inhibition Mediated by a p70 Inhibitory Killer Cell Ig-Like Receptor in Jurkat T Cells
Authors: Chwae Yong-Joon , Chang Mi Jung , Park Sang Myun , Yoon Ho , Park Hyun-Joo , Kim Se Jong , Kim Jongsun 
Published: April 2014

AbstractIn this study we investigated the molecular mechanism of the activation-induced cell death (AICD) inhibition mediated by a p70 inhibitory killer cell Ig-like receptor (KIR3DL1, also called NKB1) in Jurkat T cells. Using stable Jurkat transfectants that express KIR or CD8-KIR fusion proteins we have shown for the first time that KIR inhibits, in a ligation-independent manner, the AICD induced by PHA, PMA/ionomycin, or anti-CD3 Ab. The AICD inhibition mediated by KIR appears to result from the blockade of Fas ligand induction upon activation of the Jurkat transfectants. Moreover, the membrane-proximal 20 aa of the KIR cytoplasmic tail were determined to play a crucial role in this process. Since the membrane-proximal portion of the KIR cytoplasmic tail contains a putative protein kinase C (PKC) substrate site, we investigated the molecular interaction between KIR and PKC. Immunoprecipitation analysis demonstrated that KIR constitutively bound both to PKCα, a conventional Ca2+-dependent PKC, and to PKCθ, a novel Ca2+-independent PKC. Furthermore, an in vitro kinase assay revealed that PKC activation was blocked after PHA stimulation in Jurkat transfectants expressing KIR. These observations were supported by the finding that a recombinant KIR cytoplasmic tail also appeared to inhibit PKCα activation in vitro. Taken together these data strongly suggest that KIR inhibits the AICD of T cells by blocking Fas ligand induction upon stimulation, in a process that seems to be accomplished by PKC recruitment to the membrane-proximal PKC binding site and subsequent inhibition of PKC activation against the activating stimuli.
Expression of Antigen on Mature Lymphocytes Is Required to Induce T Cell Tolerance by Gene Therapy
Authors: Tian Chaorui , Bagley Jessamyn , Iacomini John 
Published: April 2014

Abstract
Expression of a retrovirally encoded allogeneic MHC class I gene in bone marrow-derived cells can be used to induce tolerance to the product of the retrovirally transduced gene. In this work we examined whether expression of a retrovirally transduced allogeneic MHC class I gene in bone marrow-derived cells from recombinase-activating gene-1 (RAG-1)-deficient mice was sufficient to induce tolerance when transplanted into conditioned hosts together with bone marrow from MHC-matched wild-type mice. Reconstitution of mice with either MHC-matched RAG-1-deficient or wild-type bone marrow transduced with the allogeneic MHC class I gene H-2Kb led to long-term expression of Kb on the surface of bone marrow-derived hematopoietic lineages. T cells from mice reconstituted with H-2Kb-transduced wild-type bone marrow were tolerant to Kb. In contrast, expression of Kb in the periphery of mice reconstituted with a mixture of retrovirally transduced RAG-1-deficient bone marrow and mock-transduced wild-type bone marrow fell below detectable levels by 4 wk after transplantation. T cells that developed in these mice appeared to be hyporesponsive to Kb, demonstrating that expression of Kb on bone marrow-derived APCs was not sufficient to induce tolerance. Our data suggest that induction of tolerance in molecular chimeras requires expression of the retrovirally transduced allogeneic MHC Ag on the surface of mature lymphocytes that populate the host thymus.
Evidence for Involvement of a Hydrophobic Patch in Framework Region 1 of Human V4-34-Encoded Igs in Recognition of the Red Blood Cell I Antigen
Authors: Potter Kathleen N. , Hobby Paul , Klijn Susanne , Stevenson Freda K. , Sutton Brian J. 
Published: April 2014

AbstractThe monoclonal IgM cold agglutinins that bind to the I/i carbohydrate Ags on the surface of RBCs all have Ig H chains encoded by the V4-34 gene segment. This mandatory use indicates that distinctive amino acid sequences may be involved in recognition. Critical amino acids exist in framework region 1 (FR1) of V4-34-encoded Ig, and these generate a specific Id determinant which apparently lies close to the I binding site. However, I binding by Id-expressing Ig can be modulated by sequences in complementarity-determining region (CDR)H3. Examination of the crystal structure of an anti-I cold agglutinin has revealed a hydrophobic patch in FR1 involving residue W7 on β-strand A and the AVY motif (residues 23–25) on β-strand B. In this study we used mutagenesis to show that each of the strand components of the hydrophobic patch is required for binding the I carbohydrate Ag. In addition, the crystal structure reveals that amino acids in the carboxyl-terminal region of CDRH3 form a surface region adjacent to the hydrophobic patch. We propose that the I carbohydrate Ag interacts simultaneously with the entire hydrophobic patch in FR1 and with the outside surface of CDRH3. This interaction could leave most of the conventional binding site available for binding other Ags.
The Role of Polymerase η in Somatic Hypermutation Determined by Analysis of Mutations in a Patient with Xeroderma Pigmentosum Variant
Authors: Yavuz Sule , Yavuz Akif S. , Kraemer Kenneth H. , Lipsky Peter E. 
Published: April 2014

AbstractTo determine the possible role of polymerase η (pol η) in somatic hypermutation of B cells, a mutational analysis of 24 nonproductive rearrangements from a patient with xeroderma pigmentosum variant with a defect in pol η was conducted. Although the mutational frequency of A and T bases decreased in WA (A/T, A) motifs, regardless of their RGYW (purine, G; pyrimidine, A/T) context, the overall mutational frequency of A or T bases was not affected. Moreover, the overall mutational frequency of the sequences examined was not decreased. There was an apparent increase in the number of insertions and deletions. The results are consistent with the conclusion that pol η specifically targets WA motifs. However, its overall contribution to the somatic hypermutational process does not appear to be indispensable and in its absence other mechanisms maintain mutational activity.
Mycobacterium aviumComplex Promotes Recruitment of Monocyte Hosts for HIV-1 and Bacteria
Authors: Hale-Donze Hollie , Greenwell-Wild Teresa , Mizel Diane , Doherty T. Mark , Chatterjee Delphi , Orenstein Jan M. , Wahl Sharon M. 
Published: April 2014

AbstractIn lymphoid tissues coinfected with Mycobacterium avium complex (MAC) and HIV-1, increased viral replication has been observed. This study investigates the role of MAC in perpetuating both infections through the recruitment of monocytes as potential new hosts for bacteria and HIV-1. Increased numbers of macrophages were present in the lymph nodes of patients with dual infection as compared with lymph nodes from HIV+ patients with no known opportunistic pathogens. In a coculture system, monocyte-derived macrophages were treated with HIV-1 or M. avium and its constituents to further define the mechanism whereby MAC infection of macrophages initiates monocyte migration. Monocyte-derived macrophages treated with bacteria or bacterial products, but not HIV-1, induced a rapid 2- to 3-fold increase in recruitment of monocytes. Pretreatment of the monocytes with pertussis toxin inhibited the migration of these cells, indicating a G protein-linked pathway is necessary for induction of chemotaxis and thus suggesting the involvement of chemokines. Analysis of chemokine mRNA and protein levels from M. avium-treated cultures revealed MAC-induced increases in the expression of IL-8, macrophage-inflammatory protein (MIP)-1α, and MIP-1β with donor-dependent changes in monocyte chemotactic protein-1. Pyrrolidine dithiocarbamate, an antioxidant, inhibited the activation of NF-κB and significantly diminished the MAC-induced chemotaxis, concurrently lowering the levels of monocyte chemotactic protein-1 and MIP-1β. These data demonstrate that MAC induces macrophage production of multiple chemotactic factors via NF-κB to promote monocyte migration to sites of MAC infection. In vivo, opportunistic infection may act as a recruitment mechanism in which newly arrived monocytes serve as naive hosts for both MAC and HIV-1, thus perpetuating both infections.
Divergent Role for TNF-α in IFN-γ-Induced Killing ofToxoplasma gondiiandSalmonella typhimuriumContributes to Selective Susceptibility of Patients with Partial IFN-γ Receptor 1 Deficiency
Authors: Janssen Riny , van Wengen Annelies , Verhard Els , de Boer Tjitske , Zomerdijk Timo , Ottenhoff Tom H. M. , van Dissel Jaap T. 
Published: April 2014

AbstractPatients with defects in IFN-γ- or IL-12-mediated immunity are susceptible to infections with Salmonella and non-tuberculous mycobacteria, but rarely suffer from infections with other intracellular pathogens such as Toxoplasma gondii. Here we describe macrophage and T cell function in eight individuals with partial IFN-γ receptor 1 (IFN-γR1) deficiency due to a mutation that results in elevated cell surface expression of a truncated IFN-γR1 receptor that lacks the intracellular domain. We show that various effector mechanisms dependent on IFN-γR signaling are affected to different extents. Whereas TNF-α production was normally up-regulated in response to IFN-γ, IL-12 production and CD64 up-regulation were strongly reduced, and IFN-γ-mediated killing of the intracellular pathogens Salmonella typhimurium and T. gondii was completely abrogated in patient’s macrophages. Since these patients suffer selectively from infections with non-tuberculous mycobacteria and Salmonella, but not T. gondii, despite sero-immunity in six of eight patients, which indicates previous contact with this pathogen, we next studied the role of TNF-α as a possible immune compensatory mechanism. IFN-γ-induced killing of T. gondii appeared to be partially mediated by TNF-α, and addition of TNF-α could compensate for the abrogated killing of T. gondii in the patient’s macrophages. In contrast, IFN-γ-mediated killing of S. typhimurium appeared to be independent of TNF-α. We propose that the divergent role of TNF-α in IFN-γ-induced killing of T. gondii and S. typhimurium may at least partially explain the highly selective susceptibility of patients.
Silver Activates Calcium Signals in Rat Basophilic Leukemia-2H3 Mast Cells by a Mechanism That Differs from the FcεRI-Activated Response
Authors: Suzuki Yoshihiro , Yoshimaru Tetsuro , Matsui Takashi , Ra Chisei 
Published: April 2014

Abstract
We previously showed that silver stimulates degranulation and leukotriene (LT) C4 production in rat basophilic leukemia mast cells and now show that silver induces these events by a mechanism that differs from the FcεRI-mediated response. In common with FcεRI cross-linking, silver induced tyrosine phosphorylation of extracellular signal-regulated kinases and furthermore, PD98059, a specific inhibitor of extracellular signal-regulated kinase kinase dose-dependently inhibited the silver-induced LTC4 production. In contrast to FcεRI cross-linking, silver had no effect on the production of IL-4 and TNF-α, indicating that different mechanisms are involved in the activation by these two stimuli. In line with this, silver had no or only marginal effect on the tyrosine phosphorylation of FcεRIβ, Lyn, Syk, and linker for activation of T cells, the early and crucial events in FcεRI signaling. Silver induced calcium signals that were involved in the metal-induced degranulation, but not LTC4 production. Unlike Ag, the silver-induced calcium signals were resistant to the depletion of thapsigargin-sensitive calcium stores and the inhibition of tyrosine kinases and phospholipase Cγ. These findings indicate that silver activates mast cells by bypassing the early signaling events required for the induction of calcium influx. Our data strongly suggest the existence of an alternative pathway bypassing the early signaling events in mast cell activation and indicate that silver may be useful for analyses of such alternative mechanisms.
The Immunomodulatory Actions of Prostaglandin E2 on Allergic Airway Responses in the Rat
Authors: Martin James G. , Suzuki Masaru , Maghni Karim , Pantano Rosa , Ramos-Barbón David , Ihaku Daizo , Nantel François , Denis Danielle , Hamid Qutayba , Powell William S. 
Published: April 2014

AbstractPGE2 has been reported to inhibit allergen-induced airway responses in sensitized human subjects. The aim of this study was to investigate the mechanism of anti-inflammatory actions of PGE2 in an animal model of allergic asthma. BN rats were sensitized to OVA using Bordetella pertussis as an adjuvant. One week later, an aerosol of OVA was administered. After a further week, animals were anesthetized with urethan, intubated, and subjected to measurements of pulmonary resistance (RL) for a period of 8 h after OVA challenge. PGE2 (1 and 3 μg in 100 μl of saline) was administered by insufflation intratracheally 30 min before OVA challenge. The early response was inhibited by PGE2 (3 μg). The late response was inhibited by both PGE2 (1 and 3 μg). Bronchoalveolar lavage fluid from OVA-challenged rats showed eosinophilia and an increase in the number of cells expressing IL-4 and IL-5 mRNA. These responses were inhibited by PGE2. Bronchoalveolar lavage fluid levels of cysteinyl-leukotrienes were elevated after OVA challenge and were reduced after PGE2 to levels comparable with those of sham challenged animals. We conclude that PGE2 is a potent anti-inflammatory agent that may act by reducing allergen-induced Th2 cell activation and cysteinyl-leukotriene synthesis in the rat.