bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transient Translocation of the B Cell Receptor and Src Homology 2 Domain-Containing Inositol Phosphatase to Lipid Rafts: Evidence Toward a Role in Calcium Regulation
Authors: Petrie Ryan J. , Schnetkamp Paul P. M. , Patel Kamala D. , Awasthi-Kalia Manjula , Deans Julie P. 
Published: April 2014

AbstractMembrane microdomains (lipid rafts) are enriched in selected signaling molecules and may compartmentalize receptor-mediated signals. Here, we report that in primary human B lymphocytes and in Ramos B cells B cell receptor (BCR) stimulation induces rapid and transient redistribution of a subset of engaged BCRs to lipid rafts and phosphorylation of raft-associated tyrosine kinase substrates. Cholesterol sequestration disrupted the lipid rafts, preventing BCR redistribution, but did not inhibit tyrosine kinase activation or phosphorylation of mitogen-activated protein kinase/extracellular regulated kinase. However, raft disruption enhanced the release of calcium from intracellular stores, suggesting that rafts may sequester early signaling events that down-regulate calcium flux. Consistent with this, BCR stimulation induced rapid and transient translocation of the Src homology 2 domain-containing inositol phosphatase, SHIP, into lipid rafts.
CpG-DNA-Mediated Transient Lymphadenopathy Is Associated with a State of Th1 Predisposition to Antigen-Driven Responses
Authors: Lipford Grayson B. , Sparwasser Tim , Zimmermann Stefan , Heeg Klaus , Wagner Hermann 
Published: April 2014

AbstractInfections can influence concurrent and subsequent Th1 vs Th2 immune responses to Ags. Through pattern recognition of foreign unmethylated CpG dinucleotides, the vertebrate innate immune system can sense infectious danger and typically replies with a Th1-polarized adaptive immune response. We examined whether CpG-DNA exposure would influence subsequent responses to infection and soluble Ags. CpG-DNA injection led to local lymphadenopathy characterized by maintenance of cellular composition with some biasing toward elevated dendritic cell composition. Sustained local production of IL-12 and IFN-γ from dendritic cells and T cells was shown. Prior injection by up to 2 wk with CpG-DNA protected BALB/c mice from Th2 driven lethal leishmaniasis. CpG-DNA injection by up to 5 wk before soluble Ag challenge resulted in the generation of Ag-specific CTL, Th1 recall responses to Ag, and Th1-polarized Ag-specific Abs. Thus, CpG-DNA instigated a local predisposition for intense CTL responses and Th1-polarized immune responses to subsequent infections or Ag challenge. The induction by the innate immune system of a locally contained hypersensitivity could represent a capacitating immune reaction yielding rapid conditioned responses to secondary infections.
Age-Dependent Alterations in the Assembly of Signal Transduction Complexes at the Site of T Cell/APC Interaction
Authors: Tamir Ami , Eisenbraun Michael D. , Garcia Gonzalo G. , Miller Richard A. 
Published: April 2014

Abstract
TCR interaction with peptide-MHC complexes triggers migration of protein kinases, actin-binding proteins, and other accessory molecules to the T cell/APC synapse. We used confocal immunofluorescence methods to show that the adapter protein LAT (linker for activation of T cells) and the guanine nucleotide exchange factor Vav also move to the APC interface in mouse CD4 T cells conjugated to anti-CD3 hybridoma cells, and in TCR-transgenic CD4 cells conjugated to APC bearing agonist (but not closely related nonagonist) peptides. The proportion of CD4+ T cells able to relocalize LAT or Vav, or to relocate cytoplasmic NT-AT (NF-ATc) from cytoplasm to nucleus, declines about 2-fold in aged mice. The decline in LAT relocalization is accompanied by a similar decline in tyrosine phosphorylation of LAT in CD4 cells stimulated by CD3/CD4 cross-linking. Two-color experiments show that LAT redistribution is strongly associated with relocalization of both NF-ATc and protein kinase C-θ among individual cells. LAT migration to the immunological synapse depends on actin polymerization as well as on activity of Src family kinases, but aging leads to only a small change in the percentage of CD4 cells that redistribute F-actin to the site of APC contact. These results suggest that defects in the ability of T cells from aged donors to move kinase substrates and coupling factors, including LAT and Vav, into the T cell/APC contact region may contribute to the decline with age in NF-ATc-dependent gene expression, and thus to defects in T cell clonal expansion.
Expression of a Functional FcεRI on Rat Eosinophils and Macrophages
Authors: Dombrowicz David , Quatannens Brigitte , Papin Jean-Paul , Capron André , Capron Monique 
Published: April 2014

AbstractBesides its crucial role in type I hypersensitivity reactions, IgE is involved in anti-parasite immunity. This role has been clearly demonstrated in both human and rat schistosomiasis, but remains controversial in the mouse. Since the cellular distribution of the high affinity IgE receptor, FcεRI, differs in humans and mice, it might explain the differences in effector function of IgE between the two species. In humans, eosinophils and macrophages induce IgE-dependent cytotoxicity toward Schistosoma mansoni larvae, which involves FcεRI in the case of eosinophils. In the present study, we have investigated the expression and function of FcεRI in rat eosinophils and macrophages. We demonstrate, by flow cytometry, fluorescence microscopy, and Western blot analysis, that in rats, as in humans, a functional αγ2 trimeric FcεRI is expressed on eosinophils and macrophages. We also show that these two cell types can induce IgE-mediated, FcεRI-dependent cellular cytotoxicity toward schistosomula. These results thus provide a molecular basis for the differences observed between rat and mouse regarding IgE-mediated anti-parasite immunity.
Comprehensive Assessment of Determinant Specificity, Frequency, and Cytokine Signature of the Primed CD8 Cell Repertoire Induced by a Minor Transplantation Antigen
Authors: Heeger Peter S. , Valujskikh Anna , Lehmann Paul V. 
Published: April 2014

AbstractT cell immunity is often focused on one peptide segment of a complex protein Ag, with other epitopes inducing weaker, low frequency responses or no responses at all. Such determinant hierarchy has been well characterized for MHC class II-restricted CD4 cell immunity, but is less well understood for class I-restricted CD8 cell responses. We studied class I determinant recognition in a skin transplant model with β-galactosidase (β-gal) as a minor transplantation Ag. CD8 T cells from C57BL/6 mice that rejected congenic C57BL/6 β-gal transgenic skin were tested in enzyme-linked immunospot assays for recall responses to single-step, overlapping, 9-mer peptides that spanned a 94-aa region of the β-gal sequence. This approach provided every possible class I-restricted peptide for CD8 cell recognition, allowing us to define the in vivo frequency of CD8 cells specific for each of the 86 individual peptides. While four peptides were predicted to bind to the Kb or Db molecules, only one (β-gal96–103) actually induced an immune response. No peptides outside of the motifs were recognized. Tolerization to β-gal96–103 significantly prolonged β-gal transgenic skin graft survival, confirming its immune dominance. Therefore, single-determinant dominance characterized this CD8 cell response. The data demonstrate the feasibility of large-scale, comprehensive, class I determinant mapping, an approach that should be indispensable in measuring CD8 cell immunity in humans.
Indirect Recognition of Porcine Swine Leukocyte Ag Class I Molecules Expressed on Islets by Human CD4+ T Lymphocytes
Authors: Olack Barbara , Manna Partha , Jaramillo Andrés , Steward Nancy , Swanson Carol , Kaesberg Dana , Poindexter Nancy , Howard Todd , Mohanakumar Thalachallour 
Published: April 2014

Abstract
Xenotransplantation of porcine islets is considered a viable alternative treatment for type 1 diabetes mellitus. Therefore, we characterized human PBL responding to porcine islets both in vitro by coculture and in vivo using SCID mice reconstituted with human PBLs (HuPBL-SCID) and transplanted with porcine islets. T cell lines generated in vitro and graft-infiltrating T cells obtained from HuPBL-SCID mice were CD4+-proliferated specifically to porcine islets cultured with autologous APC. This proliferation was abrogated by an anti-human class II Ab. These T cell lines also proliferated to purified swine leukocyte Ag (SLA) class I molecules in the presence of self-APC, indicating that the primary xenoantigens recognized are peptides derived from SLA. This CD4+ T cell line lysed porcine islets but not splenocytes. CD4+ T cell clones with Th0, Th1, and Th2 cytokine profiles were isolated. The Th0 and Th1 clones lysed porcine islets, whereas the Th2 clone that secreted a large amount of IL-4 was not lytic. These results demonstrate that human T cells responding to porcine islets are primarily CD4+ and recognize porcine xenoantigens by the indirect Ag pathway presentation. These activated T cells produce cytokines that lyse islets. Furthermore, we demonstrate that the major porcine xenoantigens recognized are SLA class I molecules.
B Cell Antigen Receptor-Induced Activation of Akt Promotes B Cell Survival and Is Dependent on Syk Kinase
Authors: Pogue Sarah L. , Kurosaki Tomohiro , Bolen Joseph , Herbst Ronald 
Published: April 2014

AbstractSignaling through the B cell Ag receptor (BCR) is a key determinant in the regulation of B cell physiology. Depending on additional factors, such as microenvironment and developmental stage, ligation of the BCR can trigger B lymphocyte activation, proliferation, or apoptosis. The regulatory mechanisms determining B cell apoptosis and survival are not known. Using the chicken B lymphoma cell line DT40 as a model system, we investigated the role of the serine/threonine kinase Akt in B cell activation. While parental DT40 cells undergo apoptosis in response to BCR cross-linking, cells overexpressing Akt show a greatly diminished apoptotic response. By contrast, limiting the activation of Akt, either by inhibiting phosphatidylinositol 3-kinase or by ectopic expression of the phospholipid phosphatase MMAC1, results in a significant increase in the percentage of apoptotic cells after BCR cross-linking. Using various DT40 knockout cell lines, we further demonstrate that the tyrosine kinase Syk is required for Akt activation and that Lyn tyrosine kinase inhibits Akt activation. Taken together, the data demonstrate that Akt plays an important role in B cell survival and that Akt is activated in a Syk-dependent pathway.
IL-18 Activates STAT3 in the Natural Killer Cell Line 92, Augments Cytotoxic Activity, and Mediates IFN-γ Production by the Stress Kinase p38 and by the Extracellular Regulated Kinases p44erk-1and p42erk-21
Authors: Kalina Uwe , Kauschat Doerte , Koyama Noriko , Nuernberger Heike , Ballas Karin , Koschmieder Steffen , Bug Gesine , Hofmann Wolf-Karsten , Hoelzer Dieter , Ottmann Oliver G. 
Published: April 2014

AbstractIL-18 is a regulator of NK cell function which utilizes the serine-threonine IL-1R-associated kinase signal transduction pathway and may activate additional not yet characterized signaling pathways. Here we evaluated IL-18-mediated signal transduction using the human NK cell line NK92 as a model. NK92 cells were shown by RT-PCR to express all three IL-18 receptor chains (IL-18R, accessory protein-like chain, IL-18-binding protein). Stimulation by IL-18 strongly enhanced tyrosine phosphorylation of STAT3 and of the mitogen-activated protein kinases (MAPK) p44erk-1and p42erk-2. In contrast, STAT5 was not activated. The cytolytic activity of NK92 against K562 target cells, which was augmented in a dose-dependent manner by IL-18 in the presence of trace amounts of IL-2, was suppressed by the specific inhibitors of MAPK pathways (PD098059 and SB203580). Similarly, the stimulatory effect of IL-18 on IFN-γ protein production, given in conjunction with IL-2, was counteracted by inhibition of MAPK. IL-18 alone failed to stimulate IFN-γ protein production despite inducing expression of IFN-γ mRNA. IL-2 alone stimulated neither IFN-γ mRNA expression nor IFN-γ protein production. IL-18 did not stimulate proliferation of NK92 cells, either alone or in combination with IL-2 or IL-12. Inhibition of the MAPK pathway did not significantly alter the IL-2- and IL-12-induced proliferation of NK92 cells, whereas the Janus kinase/STAT pathway inhibitor AG490 strongly suppressed proliferation. MAPK activation appears to play a prominent role in IL-18 signaling, being involved in transcription and translation of IL-18-induced IFN-γ mRNA and IL-18-induced cytolytic effects. In contrast, proliferation of NK92 cells is not affected by MAPK p44erk-1 and p42erk-2.
Impaired Natural Killing of MHC Class I-Deficient Targets by NK Cells Expressing a Catalytically Inactive Form of SHP-1
Authors: Lowin-Kropf Bente , Kunz Béatrice , Beermann Friedrich , Held Werner 
Published: April 2014

AbstractNK cell function is negatively regulated by MHC class I-specific inhibitory receptors. Transduction of the inhibitory signal involves protein tyrosine phosphatases such as SHP-1 (SH2-containing protein tyrosine phosphatase-1). To investigate the role of SHP-1 for NK cell development and function, we generated mice expressing a catalytically inactive, dominant-negative mutant of SHP-1 (dnSHP-1). In this paper we show that expression of dnSHP-1 does not affect the generation of NK cells even though MHC receptor-mediated inhibition is partially impaired. Despite this defect, these NK cells do not kill syngeneic, normal target cells. In fact dnSHP-1-expressing NK cells are hyporesponsive toward MHC-deficient target cells, suggesting that non-MHC-specific NK cell activation is significantly reduced. In contrast, these NK cells mediate Ab-dependent cell-mediated cytotoxicity and prevent the engraftment with β2-microglobulin-deficient bone marrow cells. A similar NK cell phenotype is observed in viable motheaten (mev) mice, which show reduced SHP-1 activity due to a mutation in the Shp-1 gene. In addition, NK cells in both mouse strains show a tendency to express more inhibitory MHC-specific Ly49 receptors. Our results demonstrate the importance of SHP-1 for the generation of functional NK cells, which are able to react efficiently to the absence of MHC class I molecules from normal target cells. Therefore, SHP-1 may play an as-yet-unrecognized role in some NK cell activation pathways. Alternatively, a reduced capacity to transduce SHP-1-dependent inhibitory signals during NK cell development may be compensated by the down-modulation of NK cell triggering pathways.
Fas Ligand-Induced c-Jun Kinase Activation in Lymphoid Cells Requires Extensive Receptor Aggregation But Is Independent of DAXX, and Fas-Mediated Cell Death Does Not Involve DAXX, RIP, or RAIDD
Authors: Villunger Andreas , Huang David C. S. , Holler Nils , Tschopp Juerg , Strasser Andreas 
Published: April 2014

AbstractJun kinase signaling can be elicited by death receptor activation, but the mechanism and significance of this event are still unclear. It has been reported that cross-linking Abs to Fas trigger c-Jun N-terminal kinase (JNK) signaling via caspase-mediated activation of MEKK1 (JNK kinase kinase), elevation of ceramide levels or by recruitment of death domain associated protein (DAXX) to Fas. The effect of physiological ligand for Fas on JNK signaling was never investigated, although evidence is accumulating that Fas ligand is able to induce cellular responses distinct from those evoked by Ab-mediated cross-linking of Fas. Therefore, we investigated the effect of Fas ligand on JNK signaling. Like its ability to induce cell death, Fas ligand reliably activated JNK only upon extensive aggregation of the receptor. Although this was partially dependent on caspase activation, DAXX was not required. DAXX and other death receptor-associated proteins, which have been reported to bind directly or indirectly to Fas, such as receptor interacting protein (RIP) and RIP-associated ICH-1/CED-3-homologous protein with a death domain (RAIDD), were shown to be dispensable for Fas ligand-induced apoptosis.
IFN-γ Inhibits Presentation of a Tumor/Self Peptide by CD8α− Dendritic Cells Via Potentiation of the CD8α+ Subset
Authors: Grohmann Ursula , Bianchi Roberta , Belladonna Maria L. , Silla Silvia , Fallarino Francesca , Fioretti Maria C. , Puccetti Paolo 
Published: April 2014

Abstract
Using an in vivo model of tumor/self peptide presentation for induction of class I-restricted skin test reactivity, we have previously shown that a minority population of CD8+ dendritic cells (DC) negatively regulates the induction of T cell reactivity by peptide-loaded CD8− DC in DBA/2 mice. However, the CD8− fraction can be primed by IL-12 to overcome inhibition by the CD8+ subset when the two types of DC are cotransferred into recipient hosts. We report here that exposure of CD8+ DC to IFN-γ greatly enhances their inhibitory activity on Ag presentation by the other subset, blocking the ability of IL-12-treated CD8− DC to overcome suppression. In contrast, IFN-γ has no direct effects on the APC function of the latter cells and does not interfere with IL-12 signaling. The negative regulatory effect triggered by IFN-γ in CD8+ DC appears to involve interference with tryptophan metabolism in vivo. Through tryptophan depletion affecting T cell responses, IFN-γ acting on CD8+ DC may thus contribute to regulation of immunity to tumor/self peptides presented by the CD8− subset.
T Cell Development in TCRβ Enhancer-Deleted Mice: Implications for αβ T Cell Lineage Commitment and Differentiation
Authors: Leduc Isabelle , Hempel William M. , Mathieu Noëlle , Verthuy Christophe , Bouvier Gaëlle , Watrin Françoise , Ferrier Pierre 
Published: April 2014

AbstractT cell differentiation in the mouse thymus is an intricate, highly coordinated process that requires the assembly of TCR complexes from individual components, including those produced by the precisely timed V(D)J recombination of TCR genes. Mice carrying a homozygous deletion of the TCRβ transcriptional enhancer (Eβ) demonstrate an inhibition of V(D)J recombination at the targeted TCRβ locus and a block in αβ T cell differentiation. In this study, we have characterized the T cell developmental defects resulting from the Eβ−/− mutation, in light of previously reported results of the analyses of TCRβ-deficient (TCRβ−/−) mice. Similar to the latter mice, production of TCRβ-chains is abolished in the Eβ−/− animals, and under these conditions differentiation into cell-surface TCR−, CD4+CD8+ double positive (DP) thymocytes depends essentially on the cell-autonomous expression of TCRδ-chains and, most likely, TCRγ-chains. However, contrary to previous reports using TCRβ−/− mice, a minor population of TCR γδ+ DP thymocytes was found within the Eβ−/− thymi, which differ in terms of T cell-specific gene expression and V(D)J recombinase activity, from the majority of TCR−, αβ lineage-committed DP thymocytes. We discuss these data with respect to the functional role of Eβ in driving αβ T cell differentiation and the mechanism of αβ T lineage commitment.
Increased Frequency of Surface IgA-Positive Plasma Cells in the Intestinal Lamina Propria and Decreased IgA Excretion in Hyper IgA (HIGA) Mice, a Murine Model of IgA Nephropathy with Hyperserum IgA
Authors: Kamata Tadashi , Nogaki Fumiaki , Fagarasan Sidonia , Sakiyama Toshio , Kobayashi Ikei , Miyawaki Shigeki , Ikuta Koichi , Muso Eri , Yoshida Haruyoshi , Sasayama Shigetake , Honjo Tasuku 
Published: April 2014

AbstractBecause abnormalities of mucosal immunity have been suggested in human IgA nephropathy, we examined the involvement of mucosal immunity in IgA deposition to the kidney in hyper IgA (HIGA) mice, which was established as a mouse model for human IgA nephropathy with hyperserum IgA. The number of surface IgA+B220− lymphocytes in the intestinal lamina propria (LP) of HIGA mice increased 2.7-fold at 30 wk of age as compared with those at 10 wk of age, whereas normal mice did not show such increase. The surface IgA+B220− LP lymphocytes spontaneously secreted IgA in culture. Morphological studies showed that the surface IgA+B220− lymphocytes of murine intestinal LP are identical with plasma cells (PCs). About 20% of IgA+B220− PC in LP expressed both Mac-1 and CD19, suggesting that they may derive from peritoneal B-1 cells. Cell cycle study on intestinal IgA-PCs using bromodeoxyuridine revealed no difference between HIGA mice and normal mice, suggesting that the high frequency of IgA-producing PCs in HIGA mice is not due to enhanced proliferation or prolonged survival of IgA-producing PCs in LP. In addition, IgA secretion into the gut lumen of HIGA mice decreased drastically (to one forth) with aging. These data suggest that the increased number of intestinal IgA-producing PCs and the down-regulation of IgA excretion into the intestinal lumen might synergistically contribute to the hyperserum IgA in HIGA mice and resultant IgA deposition to the kidney.
IL-4 Enhances Keratinocyte Expression of CXCR3 Agonistic Chemokines
Authors: Albanesi Cristina , Scarponi Claudia , Sebastiani Silvia , Cavani Andrea , Federici Monica , De Pità Ornella , Puddu Pietro , Girolomoni Giampiero 
Published: April 2014

AbstractIFN-induced protein of 10 kDa (IP-10), monokine induced by IFN-γ (Mig), and IFN-inducible T-cell α-chemoattractant (I-TAC) belong to the non-glutamate-leucine-arginine motif CXC chemokine family and act solely through the CXCR3 receptor for potent attraction of T lymphocytes. In this study, we evaluated the capacity of the T cell-derived cytokines IL-4, IL-10, and IL-17 to modulate IP-10, Mig, and I-TAC in cultured human keratinocytes and CXCR3 expression in T cells from allergic contact dermatitis (ACD). IL-4, but not IL-10 or IL-17, significantly up-regulated IFN-γ- or TNF-α-induced IP-10, Mig, and I-TAC mRNA accumulation in keratinocytes and increased the levels of IP-10 and Mig in keratinocyte supernatants. Immunohistochemistry of skin affected by ACD revealed that &gt;70% of infiltrating cells were reactive for CXCR3 and that CXCR3 staining colocalized in CD4+ and CD8+ T cells. Nickel-specific CD4+ and CD8+ T cell lines established from ACD skin produced IFN-γ and IL-4 and expressed moderate to high levels of CXCR3. Finally, CXCR3 agonistic chemokines released by stimulated keratinocytes triggered calcium mobilization in skin-derived nickel-specific CD4+ T cells and promoted their migration, with supernatant from keratinocyte cultures stimulated with IFN-γ and IL-4 attracting more efficaciously than supernatant from keratinocytes activated with IFN-γ alone. In conclusion, IL-4 exerts a proinflammatory function on keratinocytes by potentiating IFN-γ and TNF-α induction of IP-10, Mig, and I-TAC, which in turn may determine a prominent recruitment of CXCR3+ T lymphocytes at inflammatory reaction sites.