bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cutting Edge: T Lymphocyte Activation by Repeated Immunological Synapse Formation and Intermittent Signaling
Authors: Faroudi Mustapha , Zaru Rossana , Paulet Pierre , Müller Sabina , Valitutti Salvatore 
Published: April 2014

AbstractThe activation of biological T cell responses requires prolonged contact with APCs and sustained signaling. We investigated whether signaling must be uninterrupted to commit T cells to cytokine production or whether T cell activation may also result from summation of interrupted signals. Upon periodic addition and removal of a src kinase inhibitor, human CD4+ T cells destroyed and re-formed immunological synapses while aborting and restarting signal transduction. Remarkably, under these conditions, T cells were eventually activated to IFN-γ production and the amount of IFN-γ produced was directly related to the total signaling time despite the repeated interruptions. Our results illustrate that T cell activation does not require a stable immunological synapse and can be achieved by interrupted signaling. It is implied that T cells can add activation signals, possibly collected on multiple APCs.
Differential Expression of Smad7 Transcripts Identifies the CD4+CD45RChigh Regulatory T Cells That Mediate Type V Collagen-Induced Tolerance to Lung Allografts
Authors: Mizobuchi Teruaki , Yasufuku Kazuhiro , Zheng Yan , Haque M. Azizul , Heidler Kathleen M. , Woods Kena , Smith Gerald N. , Cummings Oscar W. , Fujisawa Takehiko , Blum Janice S. , Wilkes David S. 
Published: April 2014

AbstractRegulatory T cells (Tregs) induced by oral tolerance may suppress immunity by production of TGF-β that could also enhance Treg activity. However, all cells that are phenotypically Tregs in rats (CD4+CD45RChigh-RChigh) may not have regulatory function. Because Smad7 expression in T cells is associated with inflammation and autoimmunity, then lack of Smad7 may identify those cells that function as Tregs. We reported that feeding type V collagen (col(V)) to WKY rats (RT1l) induces oral tolerance to lung allografts (F344-RT1lvl) by T cells that produce TGF-β. The purpose of the current study was to identify the Tregs that mediate col(V)-induced tolerance, and determine Smad7 expression in these cells. RChigh cells from tolerant rats were unresponsive to allogeneic stimulation and abrogated rejection after adoptive transfer. In contrast, CD4+CD45RClow (RClow) cells from tolerant rats and RChigh or RClow cells from normal rats or untreated allograft recipients proliferated vigorously in response to donor Ags, and did not suppress rejection after adoptive transfer. TGF-β enhanced proliferation in response to col(V) presented to tolerant RChigh, but not other cells. In contrast to other cells, only RChigh cells from tolerant rats did not express Smad7. Collectively, these data show that the Tregs that mediate col(V)-induced tolerance to lung allografts do not express SMAD7 and, therefore, are permissive to TGF-β-mediated signaling.
Antibody Repertoire and Gene Expression Profile: Implications for Different Developmental and Functional Traits of Splenic and Peritoneal B-1 Lymphocytes
Authors: Kretschmer Karsten , Jungebloud Anke , Stopkowicz Jana , Stoermann Britta , Hoffmann Reinhard , Weiss Siegfried 
Published: April 2014

AbstractIn L2 mice, a high expression level of the transgenic λ2315 L chain results in nearly complete exclusion of endogenous L chains and a predominance of B-1a cells. In this study, we show that splenic and peritoneal B-1a cells differ considerably in their Ab repertoire and gene expression profile. Splenic B-1a cells exhibit a more diversified repertoire under L chain limitation. Despite oligoclonal overlaps between both B-1a compartments, some B cell receptor specificities are clearly restricted to the peritoneum. The capacity of peritoneal B-1a cells to enter the splenic B-1a compartment was found to be very limited. Gene expression profiling revealed genes up-regulated in splenic B-1a cells that are involved in mediating specialized first-line-of-defense effector functions and interaction with T cells. Thus, splenic and peritoneal B-1a cells differ not only in their developmental program but also in functional properties.
Hemopoietic Function After Use of IL-1 with Chemotherapy or Irradiation
Authors: Gardner Renee V. , McKinnon Evangeline , Poretta Connie , Leiva Lily 
Published: April 2014

AbstractIL-1 has putative chemo- and radioprotective properties, but its effects on primitive hemopoietic stem cell (PHSC) and early multilineage precursor function when given with these modalities is unknown. C57BL6/J (B6) mice, given IL-1 20 h before cyclophosphamide (200 mg/kg for four biweekly doses) or before irradiation (500 cGy), were sacrificed after 4 wk. Their marrow was used as donor cells, and that from B6-HbbdGpi1a (B6-GPI) mice was used as competitor cells in competitive repopulation. Percentages of B6 cells were measured at 30 and 150 days. Stem cell numbers were estimated using binomial statistics. IL-1 alone did not affect stem cell function. As expected, significant declines in early multilineage precursor and PHSC function occurred with chemotherapy and radiation alone. IL-1 with chemotherapy led to exacerbation of these losses in function and numbers (p &lt; 0.05). A similar reduction in function occurred using IL-1 before irradiation. In summary, IL-1 with chemotherapy or radiation worsened chemotherapy- and radiation-induced functional damage to PHSC and other hemopoietic precursors, suggesting that improvements in survival do not necessarily translate into preservation of hemopoietic function.
Theileria parva-Transformed T Cells Show Enhanced Resistance to Fas/Fas Ligand-Induced Apoptosis
Authors: Küenzi Peter , Schneider Pascal , Dobbelaere Dirk A. E. 
Published: April 2014

AbstractLymphocyte homeostasis is regulated by mechanisms that control lymphocyte proliferation and apoptosis. Activation-induced cell death is mediated by the expression of death ligands and receptors, which, when triggered, activate an apoptotic cascade. Bovine T cells transformed by the intracellular parasite Theileria parva proliferate in an uncontrolled manner and undergo clonal expansion. They constitutively express the death receptor Fas and its ligand, FasL but do not undergo apoptosis. Upon elimination of the parasite from the host cell by treatment with a theilericidal drug, cells become increasingly sensitive to Fas/FasL-induced apoptosis. In normal T cells, the sensitivity to death receptor killing is regulated by specific inhibitor proteins. We found that anti-apoptotic proteins such as cellular (c)-FLIP, which functions as a catalytically inactive form of caspase-8, and X-chromosome-linked inhibitor of apoptosis protein (IAP) as well as c-IAP, which can block downstream executioner caspases, are constitutively expressed in T. parva-transformed T cells. Expression of these proteins is rapidly down-regulated upon parasite elimination. Antiapoptotic proteins of the Bcl-2 family such as Bcl-2 and Bcl-xL are also expressed but, in contrast to c-FLIP, c-IAP, and X-chromosome-linked IAP, do not appear to be tightly regulated by the presence of the parasite. Finally, we show that, in contrast to the situation in tumor cells, the phosphoinositide 3-kinase/Akt pathway is not essential for c-FLIP expression. Our findings indicate that by inducing the expression of antiapoptotic proteins, T. parva allows the host cell to escape destruction by homeostatic mechanisms that would normally be activated to limit the continuous expansion of a T cell population.
Enhanced Priming of Multispecific, Murine CD8+ T Cell Responses by DNA Vaccines Expressing Stress Protein-Binding Polytope Peptides
Authors: Schirmbeck Reinhold , Fissolo Nicolas , Chaplin Paul , Reimann Jörg 
Published: April 2014

AbstractA polytope DNA vaccine (pCI/pt10) was used that encodes within a 106-residue sequence 10-well characterized epitopes binding MHC class I molecules encoded by the K, D, or L locus (of H-2d, H-2b, and H-2k haplotype mice). The pCI/pt10 DNA vaccine efficiently primed all four Kb/Db-restricted CD8+ T cell responses in H-2b mice, but was deficient in stimulating most CD8+ T cell responses in H-2d mice. Comparing CD8+ T cell responses elicited with the pCI/pt10 DNA vaccine in Ld+ BALB/c and Ld− BALB/cdm2 (dm2) mice revealed that Ld-restricted CD8+ T cell responses down-regulated copriming of CD8+ T cell responses to other epitopes regardless of their restriction or epitope specificity. Although the pt10 vaccine could thus efficiently co prime multispecific CD8+ T cell responses, this priming was impaired by copriming Ld-restricted CD8+ T cell responses. When the pt10 sequence was fused to a 77-residue DnaJ-homologous, heat shock protein 73-binding domain (to generate a 183-residue cT77-pt10 fusion protein), expression and immunogenicity (for CD8+ T cells) of the chimeric Ag were greatly enhanced. Furthermore, priming of multispecific CD8+ T cell responses was readily elicited even under conditions in which the suppressive, Ld-dependent immunodominance operated. The expression of polytope vaccines as chimeric peptides that endogenously capture stress proteins during in situ production thus facilitates copriming of CD8+ T cell populations with a diverse repertoire.
CD4+ NKT Cells, But Not Conventional CD4+ T Cells, Are Required to Generate Efferent CD8+ T Regulatory Cells Following Antigen Inoculation in an Immune-Privileged Site
Authors: Nakamura Takahiko , Sonoda Koh-Hei , Faunce Douglas E. , Gumperz Jenny , Yamamura Takashi , Miyake Sachiko , Stein-Streilein Joan 
Published: April 2014

AbstractFollowing inoculation of Ag into the anterior chamber (a.c.), systemic tolerance develops that is mediated in part by Ag-specific efferent CD8+ T regulatory (Tr) cells. This model of tolerance is called a.c.-associated immune deviation. The generation of the efferent CD8+ Tr cell in a.c.-associated immune deviation is dependent on IL-10-producing, CD1d-restricted, invariant Vα14+ NKT (iNKT) cells. The iNKT cell subpopulations are either CD4+ or CD4−CD8− double negative. This report identifies the subpopulation of iNKT cells that is important for induction of the efferent Tr cell. Because MHC class II−/− (class II−/−) mice generate efferent Tr cells following a.c. inoculation, we conclude that conventional CD4+ T cells are not needed for the development of efferent CD8+ T cells. Furthermore, Ab depletion of CD4+ cells in both wild-type mice (remove both conventional and CD4+ NKT cells) and class II−/− mice (remove CD4+ NKT cells) abrogated the generation of Tr cells. We conclude that CD4+ NKT cells, but not the class II molecule or conventional CD4+ T cells, are required for generation of efferent CD8+ Tr cells following Ag introduction into the eye. Understanding the mechanisms that lead to the generation of efferent CD8+ Tr cells may lead to novel immunotherapy for immune inflammatory diseases.
The Lyn Tyrosine Kinase Negatively Regulates Neutrophil Integrin Signaling
Authors: Pereira Shalini , Lowell Clifford 
Published: April 2014

AbstractThe Src family kinase Lyn has been shown to play both stimulatory and inhibitory roles within several hemopoietic cell types. In this study, we investigated the role played by Lyn in neutrophil integrin signaling. Loss of Lyn resulted in a hyperresponsive phenotype on engagement of surface integrins at low valency. Lyn−/− neutrophils displayed enhanced respiratory burst, secondary granule release, and a hyperadhesive phenotype when adherent to surfaces coated with either cellular counterreceptors or extracellular matrix proteins. In contrast, Lyn-deficient and wild-type cells expressed similar levels of surface integrins and responded equivalently to activating agents in suspension, indicating that the enhanced responses of lyn−/− cells was specific to the integrin signaling pathways. Lyn-deficient macrophages also displayed a hyperadhesive phenotype. Biochemical analysis of macrophages from lyn−/− mice revealed that Lyn plays an essential role in the adhesion-dependent phosphorylation of the immunoreceptor tyrosine-based inhibitory motif of the inhibitory receptors SIRP1α and PIR-B, which in turn recruit the phosphatase SHP-1. These observations suggest that reduced mobilization of SHP-1 to the membrane in lyn−/− neutrophils results in a hyperadhesive and hyperactive phenotype. This hypothesis is further supported by the fact that neutrophils from mev/mev mice, which have significantly reduced SHP-1 activity, are also hyperresponsive following integrin engagement. This is the first direct evidence using primary leukocytes from lyn−/− mice that this kinase functions as a negative regulator in integrin signaling.
B Cell Receptor-Mediated Syk-Independent Activation of Phosphatidylinositol 3-Kinase, Ras, and Mitogen-Activated Protein Kinase Pathways
Authors: Yokozeki Takeaki , Adler Kristin , Lankar Danielle , Bonnerot Christian 
Published: April 2014

AbstractThe Syk tyrosine kinase is a key molecule in the development of the B cell lineage and the activation of B lymphocytes after Ag recognition by the B cell Ag receptor (BCR). Several genetic studies with chicken B cells have reported that the recruitment of Syk by BCR is essential for activation of a cascade of signaling molecules including phosphatidylinositol 3-kinase, mitogen-activated protein kinases, Ras signaling pathways, phospholipase C-γ2 activation, and calcium mobilization. The identification of a Syk-deficient mouse IIA1.6/A20 B cell line provided us the opportunity to investigate Syk-mediated signaling in mouse. Surprisingly, phosphatidylinositol 3-kinase, Ras, and mitogen-activated protein kinases were activated upon BCR cross-linking in these Syk-deficient mouse B cells, whereas, as expected from results obtained in chicken B cells, phospholipase C-γ2 activation and calcium mobilization were impaired as well as the NF-κB pathway. These results indicate that BCR signaling is not strictly dependent on Syk expression in mouse IIA1.6/A20 B cells. Thus, B lymphocyte activation may be initiated by Syk-dependent and Syk-independent signaling cascades.
Identification and Characterization of a Novel Regulatory Factor: IgA-Inducing Protein
Authors: Austin Amy S. , Haas Karen M. , Naugler Sasha M. , Bajer Anna A. , Garcia-Tapia David , Estes D. Mark 
Published: April 2014

AbstractIgA is the predominant Ig isotype in mucosal secretions and thus plays a pivotal role in host defense. The mechanisms by which IgA expression is regulated may differ among species and involve multiple pathways. Various cytokines and costimulators have been identified which regulate expression of this isotype, including IL-10, IL-2, vasoactive intestinal peptide, and TGF-β. We have tested a wide array of known factors, but only under very limited conditions do these factors mediate substantial IgA production in vitro from bovine B cells. In response to these findings, we generated a cDNA library in a mammalian expression vector from activated cells derived from bovine gut-associated lymphoid tissues (Peyer’s patch and mesenteric lymph node cells) as a source of soluble factor(s) that may regulate IgA production. We have identified a novel factor, IgA-inducing protein, which stimulates relatively high levels of IgA production in vitro following CD40 stimulation in coculture with IL-2. Our data suggest that IgA-inducing protein regulates IgA by acting as a switch or differentiation factor and is expressed in a variety of lymphoid and nonlymphoid tissues.
Positive Modulation of IL-12 Signaling by Sphingosine Kinase 2 Associating with the IL-12 Receptor β1 Cytoplasmic Region
Authors: Yoshimoto Takayuki , Furuhata Masae , Kamiya Sadahiro , Hisada Masayuki , Miyaji Hiroko , Magami Yasushi , Yamamoto Koh , Fujiwara Hiromi , Mizuguchi Junichiro 
Published: April 2014

AbstractIL-12 is a key immunoregulatory cytokine that promotes Th1 differentiation and cell-mediated immune responses. IL-12 stimulation results in the activation of Janus kinase 2 and tyrosine kinase 2 and, subsequently, STAT4 and STAT3. In addition, mitogen-activated protein kinase kinase 6/p38 mitogen-activated protein kinase and phosphatidylinositol 3-kinase/Akt pathways have been recently demonstrated to be activated by IL-12 and play an important role in IL-12 signaling. To further elucidate the molecular mechanism underlying IL-12 signaling, we have performed a yeast two-hybrid screening and identified mouse sphingosine kinase 2 (SPHK2) as a molecule associating with the mouse IL-12Rβ1 cytoplasmic region. Analyses of various mutants of each molecule revealed that the region including the proline-rich domain in SPHK2 is probably responsible for the binding to IL-12Rβ1, while the regions including the carboxyl terminus and Box II in the IL-12Rβ1 cytoplasmic region appear to be involved in the binding to SPHK2. Transient expression of wild-type SPHK2 in T cell hybridoma augmented IL-12-induced STAT4-mediated transcriptional activation. Ectopic expression of dominant-negative SPHK2 in Th1 cell clone significantly reduced IL-12-induced IFN-γ production, while that of wild-type SPHK2 enhanced it. In contrast, the expression minimally affected IL-12-induced proliferation. A similar decrease in IL-12-induced IFN-γ production was observed when dominant-negative SPHK2 was expressed in activated primary T cells using a retroviral expression system. These results suggest that SPHK2 associates with the IL-12Rβ1 cytoplasmic region and probably plays a role in modulating IL-12 signaling.
SLP-76 Coordinates Nck-Dependent Wiskott-Aldrich Syndrome Protein Recruitment with Vav-1/Cdc42-Dependent Wiskott-Aldrich Syndrome Protein Activation at the T Cell-APC Contact Site
Authors: Zeng Rong , Cannon Judy L. , Abraham Robert T. , Way Michael , Billadeau Daniel D. , Bubeck-Wardenberg Julie , Burkhardt Janis K. 
Published: April 2014

Abstract
We have shown previously that Wiskott-Aldrich syndrome protein (WASP) activation at the site of T cell-APC interaction is a two-step process, with recruitment dependent on the proline-rich domain and activation dependent on binding of Cdc42-GTP to the GTPase binding domain. Here, we show that WASP recruitment occurs through binding to the C-terminal Src homology 3 domain of Nck. In contrast, WASP activation requires Vav-1. In Vav-1-deficient T cells, WASP recruitment proceeds normally, but localized activation of Cdc42 and WASP is disrupted. The recruitment and activation of WASP are coordinated by tyrosine-phosphorylated Src homology 2 domain-containing leukocyte protein of 76 kDa, which functions as a scaffold, bringing Nck and WASP into proximity with Vav-1 and Cdc42-GTP. Taken together, these findings reconstruct the signaling pathway leading from TCR ligation to localized WASP activation.
Analysis of HLA-E Peptide-Binding Specificity and Contact Residues in Bound Peptide Required for Recognition by CD94/NKG2
Authors: Miller Joseph D. , Weber Dominique A. , Ibegbu Chris , Pohl Jan , Altman John D. , Jensen Peter E. 
Published: April 2014

AbstractThe MHC class Ib molecule HLA-E is the primary ligand for CD94/NKG2A-inhibitory receptors expressed on NK cells, and there is also evidence for TCR-mediated recognition of this molecule. HLA-E preferentially assembles with a homologous set of peptides derived from the leader sequence of class Ia molecules, but its capacity to bind and present other peptides remains to be fully explored. The peptide-binding motif of HLA-E was investigated by folding HLA-E in vitro in the presence of peptide libraries derived from a nonameric leader peptide sequence randomized at individual anchor positions. A high degree of selectivity was observed at four of five total anchor positions, with preference for amino acids present in HLA-E-binding peptides from class Ia leader sequences. Selectivity was also observed at the nonanchor P5 position, with preference for positively charged amino acids, suggesting that electrostatic interactions involving the P5 side chain may facilitate assembly of HLA-E peptide complexes. The observed HLA-E peptide-binding motif was strikingly similar to that previously identified for the murine class Ib molecule, Qa-1. Experiments with HLA-E tetramers bearing peptides substituted at nonanchor positions demonstrated that P5 and P8 are primary contact residues for interaction with CD94/NKG2 receptors. A conservative replacement of Arg for Lys at P5 completely abrogated binding to CD94/NKG2. Despite conservation of peptide-binding specificity in HLA-E and Qa-1, cross-species tetramer-staining experiments demonstrated that the interaction surfaces on CD94/NKG2 and the class Ib ligands have diverged between primates and rodents.
Protein Expression and Peptide Binding Suggest Unique and Interacting Functional Roles for HLA-E, F, and G in Maternal-Placental Immune Recognition
Authors: Ishitani Akiko , Sageshima Noriko , Lee Ni , Dorofeeva Natalia , Hatake Katsuhiko , Marquardt Hans , Geraghty Daniel E. 
Published: April 2014

AbstractIn this study we focused on the structure and expression of the HLA-E, F, and G class I complexes in placental tissue. Structural analysis included an examination of the peptides bound to soluble and membrane forms of the HLA-G complex isolated directly from placenta. An important distinction was observed from HLA-G bound peptides previously isolated from transfectant cells. Thus, the number of distinct moieties bound to placental-derived proteins was substantially lower than that bound to transfectant-derived HLA-G. Indeed, a single peptide species derived from a cytokine-related protein alone accounted for 15% of the molar ratio of HLA-G bound peptide. To further examine HLA-E and its potential to bind peptide, notably that derived from HLA-G, we combined new Abs to examine expression in placental tissues for all the known forms of the nonclassical class I molecules. Whereas membrane HLA-G was found in extravillous trophoblasts, soluble HLA-G was found in all placental trophoblasts, including villous cytotrophoblasts and syncitiotrophoblasts. Further, HLA-E was found in all cells that expressed either form of HLA-G, consistent with HLA-E being complexed with the HLA-G signal sequence-derived nonamer in these cells. Finally, using new reagents specific for HLA-F, a restricted pattern of expression was observed, primarily on extravillous trophoblasts that had invaded the maternal decidua. Comparative staining indicated that HLA-F was on the surface of these cells, defining them as the first to demonstrate surface expression of this Ag and the first cell type identified to express all three nonclassical HLA class I Ags simultaneously.
Inhibition of IFN-γ-Inducible Protein-10 Abrogates Colitis in IL-10−/− Mice
Authors: Singh Udai P. , Singh Shailesh , Taub Dennis D. , Lillard James W. 
Published: April 2014

AbstractA deficiency in understanding the steps responsible for colitis is the lack of comprehension for the role chemokines play in mucosal inflammation. IFN-γ-inducible protein-10 (IP-10) and CXCR3 are highly expressed at sites of colitis. Our findings show that IP-10 significantly contributes to the development of Th1 and inflammatory responses. Specifically, IP-10 inhibition in IL-10−/− mice attenuates the associated increases in serum and/or local amyloid A, IL-2, IL-6, TNF-α, IFN-γ, IL-1α, and IL-1β with colitis as compared with IL-10−/− mice that develop colitis similar to human Crohn’s disease. Correspondingly, the rate or intensity of inflammation in IL-10−/− mice treated with anti-IP-10 Abs showed improved scoring of inflammation, compared with control IL-10−/− mice. This study provides important and novel information regarding IP-10 as a target for the treatment of colitis.