bluuebunny/crossref_metadata_2025_split huggingface dataset:
Antisense Knockdown of Sphingosine Kinase 1 in Human Macrophages Inhibits C5a Receptor-Dependent Signal Transduction, Ca2+ Signals, Enzyme Release, Cytokine Production, and Chemotaxis
Authors: Melendez Alirio J. , Ibrahim Farazeela Bte Mohd 
Published: April 2014

Abstract
The anaphylatoxin C5a is produced following the activation of the complement system and is associated with a variety of pathologies, including septic shock and adult respiratory distress syndrome, and with immune complex-dependent diseases such as rheumatoid arthritis. C5a has been shown to regulate inflammatory functions by interacting with its receptor, C5aR, which belong to the rhodopsin family of seven-transmembrane GPCRs. However, the intracellular signaling pathways triggered by C5aR on immune-effector cells are not well understood. In this report we present data showing that, in human monocyte-derived macrophages, C5aR uses the intracellular signaling molecule sphingosine kinase (SPHK)1 to trigger various physiological responses. Our data show that C5a rapidly stimulates the generation of sphingosine-1-phosphate, SPHK activity, and membrane translocation of SPHK1. Using an antisense oligonucleotide against SPHK1, we show that knockdown of SPHK1 abolishes the C5a-triggered intracellular Ca2+ signals, degranulation, cytokine generation, and chemotaxis. Our study shows for the first time that SPHK1 not only plays a key role in the generation and release of proinflammatory mediators triggered by anaphylatoxins from human macrophages but is also involved in the process of immune cell motility, thus pointing out SPHK1 as a potential therapeutic target for the treatment of inflammatory and autoimmune diseases.
Regulation of Thymus Size by Competition for Stromal Niches among Early T Cell Progenitors
Authors: Prockop Susan E. , Petrie Howard T. 
Published: April 2014

Abstract
Thymic T cell production is characterized by differentiating waves of non-self-renewing, bone marrow-derived progenitors. The factors constraining new progenitor recruitment, intrathymic precursor expansion, and thymus size remain enigmatic, but are believed to be controlled by a feedback loop responding to lymphoid cellularity and competition for stromal niches. In this study, we show that competition for stromal niches does occur, but is solely limited to cells at the early CD4−8− precursor stages of differentiation. The overall size of the organ is determined both by this limitation on early precursor expansion, and by a second, cell-intrinsic limit on expansion of progenitor cells transiting to the CD4+8+ stage. Together with asymmetric use of marrow-derived progenitors to reconstitute the intrathymic pool, these processes facilitate continuous generation of new T cells while maintaining a relatively stable organ size.
Lipid Raft-Associated GTPase Signaling Controls Morphology and CD8+ T Cell Stimulatory Capacity of Human Dendritic Cells
Authors: Jaksits Silvia , Bauer Wolfgang , Kriehuber Ernst , Zeyda Maximilian , Stulnig Thomas M. , Stingl Georg , Fiebiger Edda , Maurer Dieter 
Published: April 2014

Abstract
Their eponymous morphology and unique ability to activate naive T cells are hallmark features of dendritic cells (DCs). Specific properties of the actin cytoskeleton may define both characteristics. In search for regulators that coordinate DC phenotype and function, we observed strongly increased expression of the actin-remodeling GTPases Cdc42 and Rac1 during DC development from human stem cells. Cdc42 and Rac1 are constitutively active in immature DCs, and their activity is further up-regulated by maturational stimuli such as LPS or CD40L. Activation of Rac1 is associated with its rapid recruitment into lipid rafts. Cdc42 is not recruited into rafts, but readily activated by raft-associated moieties. The functional interplay of rafts, GTPases, and cortical actin is further shown by GTPase activation and actin remodeling after pharmacological disruption of lipid rafts and by the loss of the actin-based DC morphology by transfection of dominant-negative Cdc42 and Rac1. Both Cdc42 and Rac1 also control the transport of essential immunostimulatory molecules to the DC surface. Transfection with dominant-negative GTPases led to reduced surface expression of MHC class I and CD86. Consecutively, DCs display a reduced stimulatory capacity for CD8+ T cells, whereas MHC class II-dependent stimulation of CD4+ T cells remains unperturbed. We conclude that Cdc42 and Rac1 signaling controls DC morphology and conditions DCs for efficient CD8+ T cell stimulation.
CpG-C Immunostimulatory Oligodeoxyribonucleotide Activation of Plasmacytoid Dendritic Cells in Rhesus Macaques to Augment the Activation of IFN-γ-Secreting Simian Immunodeficiency Virus-Specific T Cells
Authors: Teleshova Natalia , Kenney Jessica , Jones Jennifer , Marshall Jason , Van Nest Gary , Dufour Jason , Bohm Rudolf , Lifson Jeffrey D. , Gettie Agegnehu , Pope Melissa 
Published: April 2014

Abstract
There are two principle subsets of dendritic cells (DCs); CD11c+CD123− myeloid DCs (MDCs) and CD11c−CD123+ plasmacytoid DCs (PDCs). DC activation via TNF-TNFRs (e.g., CD40L) and TLRs (e.g., immunostimulatory oligodeoxyribonucleotides (ISS-ODNs)) is crucial for maximal stimulation of innate and adaptive immunity. Macaque DC biology is being studied to improve HIV vaccines using the SIV macaque model. Using lineage (Lin) markers to exclude non-DCs, Lin−HLA-DR+CD11c+CD123− MDCs and Lin−HLA-DR+CD11c−CD123+ PDCs were identified in the blood of uninfected macaques and healthy macaques infected with SIV or simian-human immunodeficiency virus. Overnight culture of DC-enriched Lin-depleted cells increased CD80 and CD86 expression. IL-12 production and CD80/CD86 expression by MDC/PDC mixtures was further enhanced by CD40L and ISS-ODN treatment. A CpG-B ISS-ODN increased CD80/CD86 expression by PDCs, but resulted in little IFN-α secretion unless IL-3 was added. In contrast, a CpG-C ISS-ODN and aldrithiol-2-inactivated (AT-2) SIV induced considerable PDC activation and IFN-α release without needing exogenous IL-3. The CpG-C ISS-ODN also stimulated IL-12 release (unlike AT-2 SIV) and augmented DC immunostimulatory activity, increasing SIV-specific T cell IFN-γ production induced by AT-2 SIV-presenting MDC/PDC-enriched mixtures. These data highlight the functional capacities of MDCs and PDCs in naive as well as healthy, infected macaques, revealing a promising CpG-C ISS-ODN-driven DC activation strategy that boosts immune function to augment preventative and therapeutic vaccine efficacy.
IFN-α Subtypes Differentially Affect Human T Cell Motility
Authors: Foster Graham R. , Masri Siti H. , David Rachel , Jones Meleri , Datta Arpita , Lombardi Giovanna , Runkell Laura , de Dios Carole , Sizing Irene , James Martha J. , Marelli-Berg Federica M. 
Published: April 2014

Abstract
The type I IFN family includes 14 closely related antiviral cytokines that are produced in response to viral infections. They bind to a common receptor, and have qualitatively similar biological activities. The physiological relevance of this redundancy is still unclear. In this study, we analyzed and compared the effects of two potent antiviral type I IFNs, IFN-α2 and IFN-α8, on the motility of various populations of human T lymphocytes in vitro. In this study, we show that IFN-α2 induces chemokinesis of both CD4+ and CD8+ T cells at various stages of differentiation, and induces functional changes that result in enhanced T cell motility, including up-regulation of the integrins LFA-1 and VLA-4, and subsequently, increased ICAM-1- and fibronectin-dependent migration. In contrast, IFN-α8 did not affect T cell motility, despite having similar antiviral properties and similar effects on the induction of the antiviral protein MxA. However, transcription of other IFN-stimulated genes showed that transcription of these genes is selectively activated by IFN-α2, but not IFN-α8, in T cells. Finally, while the antiviral activity of the two subtypes is inhibited by Abs against the two subunits of the IFN-α receptor, the chemokinetic effect of IFN-α2 is selectively blocked by Abs against the A1 receptor subunit. These observations are consistent with the possibility that subtype-specific intracellular signaling pathways are activated by type I IFNs in T lymphocytes.
T Cells Signaled by NF-κB− Dendritic Cells Are Sensitized Not Anergic to Subsequent Activation
Authors: Thompson Angus G. , O’Sullivan Brendan J. , Beamish Heather , Thomas Ranjeny 
Published: April 2014

Abstract
Paradoxically, while peripheral self-tolerance exists for constitutively presented somatic self Ag, self-peptide recognized in the context of MHC class II has been shown to sensitize T cells for subsequent activation. We have shown that MHC class II+CD86+CD40− DC, which can be generated from bone marrow in the presence of an NF-κB inhibitor, and which constitutively populate peripheral tissues and lymphoid organs in naive animals, can induce Ag-specific tolerance. In this study, we show that CD40− human monocyte-derived dendritic cells (DC), generated in the presence of an NF-κB inhibitor, signal phosphorylation of TCRζ, but little proliferation or IFN-γ in vitro. Proliferation is arrested in the G1/G0 phase of the cell cycle. Surprisingly, responding T cells are neither anergic nor regulatory, but are sensitized for subsequent IFN-γ production. The data indicate that signaling through NF-κB determines the capacity of DC to stimulate T cell proliferation. Functionally, NF-κB−CD40−class II+ DC may either tolerize or sensitize T cells. Thus, while CD40− DC appear to “prime” or prepare T cells, the data imply that signals derived from other cells drive the generation either of Ag-specific regulatory or effector cells in vivo.
Natural, Proteolytic Release of a Soluble Form of Human IL-15 Receptor α-Chain That Behaves as a Specific, High Affinity IL-15 Antagonist
Authors: Mortier Erwan , Bernard Jérôme , Plet Ariane , Jacques Yannick 
Published: April 2014

Abstract
IL-15 and IL-2 are two structurally and functionally related cytokines whose high affinity receptors share the IL-2R β-chain and γ-chain in association with IL-15R α-chain (IL-15Rα) or IL-2R α-chain, respectively. Whereas IL-2 action seems restricted to the adaptative T cells, IL-15 appears to be crucial for the function of the innate immune responses, and the pleiotropic expression of IL-15 and IL-15Rα hints at a much broader role for the IL-15 system in multiple cell types and tissues. In this report, using a highly sensitive radioimmunoassay, we show the existence of a soluble form of human IL-15Rα (sIL-15Rα) that arises from proteolytic shedding of the membrane-anchored receptor. This soluble receptor is spontaneously released from IL-15Rα-expressing human cell lines as well as from IL-15Rα transfected COS-7 cells. This release is strongly induced by PMA and ionomycin, and to a lesser extent by IL-1β and TNF-α. The size of sIL-15Rα (42 kDa), together with the analysis of deletion mutants in the ectodomain of IL-15Rα, indicates the existence of cleavage sites that are proximal to the plasma membrane. Whereas shedding induced by PMA was abrogated by the synthetic matrix metalloproteinases inhibitor GM6001, the spontaneous shedding was not, indicating the occurrence of at least two distinct proteolytic mechanisms. The sIL-15Rα displayed high affinity for IL-15 and behaved as a potent and specific inhibitor of IL-15 binding to the membrane receptor, and of IL-15-induced cell proliferation (IC50 in the range from 3 to 20 pM). These results suggest that IL-15Rα shedding may play important immunoregulatory functions.
The Rate of the CD8-Dependent Initial Reduction in Tumor Volume Is Not Limited by Contact-Dependent Perforin, Fas Ligand, or TNF-Mediated Cytolysis
Authors: Hollenbaugh Joseph A. , Reome Joyce , Dobrzanski Mark , Dutton Richard W. 
Published: April 2014

Abstract
Established EG7 tumors expressing OVA and growing at an intradermal site become rapidly reduced in size following adoptive therapy with in vitro-generated type I CD8 T cell (Tc1) effectors generated from naive CD8 T cells from transgenic TCR OVA-specific mice. Tc1 effectors kill EG7 target cells in vitro by a perforin-dependent mechanism. However, we show that there is no quantitative diminution of the initial phase of antitumor activity in vivo, whether the Tc1 effectors are derived from perforin-, Fas ligand-, or TNF-deficient transgenic TCR mice or whether the recipients are perforin deficient. Tumors are also equally well controlled whether the Tc1 effectors come from mice deficient in perforin plus Fas ligand or perforin plus TNF. Control of tumor growth is diminished when Tc1 effectors generated from IFN-γ-deficient mice are used. We conclude that control of tumor growth is not in any way affected by loss of contact-mediated lytic mechanisms, and conclude that the CD8 effectors must act by recruiting host effector mechanisms to control tumor growth.
Endogenous Nitric Oxide Protects against T Cell-Dependent Lethality during Graft-versus-Host Disease and Idiopathic Pneumonia Syndrome
Authors: Hongo David , Bryson J. Scott , Kaplan Alan M. , Cohen Donald A. 
Published: April 2014

Abstract
The pathogenesis of idiopathic pneumonia syndrome (IPS), a noninfectious pulmonary complication of allogeneic bone marrow transplantation (BMT), has not been fully elucidated. However, several contributing factors have been proposed, including lung injury caused by reactive oxygen and nitrogen intermediates during preconditioning and development of graft-vs-host disease (GVHD). Studies on the role of reactive oxygen and nitrogen intermediates in IPS have yielded conflicting results. We have described a murine model of IPS, in which the onset of lung inflammation was delayed by several weeks relative to GVHD. This study evaluated whether the delay in onset of IPS was due to slow turnover of NO-producing, immunosuppressive alveolar macrophages (AM) following BMT. The results indicated that AM were immunosuppressive due to synthesis of NO. However, NO production and immunosuppressive activity by AM did not decline after BMT, but rather remained elevated throughout the 12-wk development of GVHD and IPS. In a 14-day model of IPS, continuous inhibition of NO with aminoguanidine (AG) reduced signs of IPS/GVHD, but also led to higher mortality. When AG treatment was initiated after onset of IPS/GVHD, rapid mortality occurred that depended on the severity of IPS/GVHD. AG-enhanced mortality was not due to inhibition of marrow engraftment, elevated serum TNF-α, liver injury, or hypertensive responses. In contrast, T cells were involved, because depletion of CD4+ lymphocytes 24 h before AG treatment prevented mortality. Thus, NO production following allogeneic BMT affords a protective effect that helps down-regulate injury caused by T cells during GVHD and IPS.
ICOS Expression by Activated Human Th Cells Is Enhanced by IL-12 and IL-23: Increased ICOS Expression Enhances the Effector Function of Both Th1 and Th2 Cells
Authors: Wassink Lianne , Vieira Pedro L. , Smits Hermelijn H. , Kingsbury Gillian A. , Coyle Anthony J. , Kapsenberg Martien L. , Wierenga Eddy A. 
Published: April 2014

Abstract
Previous mouse studies have shown that IL-4 increases the expression of ICOS on activated Th cells, resulting in enhanced ICOS expression on Th2 cells. In this study, we show that ICOS expression on human Th cells is not increased by IL-4, but by IL-12 and by IL-23 instead. Consequently, ICOS expression during IL-12-driven Th1 cell polarization was transiently increased compared with the levels on Th0 cells and IL-4-driven Th2 cells. Addition of IL-12 and/or IL-23 during restimulation increased ICOS expression to the same extent on pre-established Th1, Th2, and Th0 cells, indicating that ICOS levels are not stably imposed by prior polarization. In contrast to the findings in the mouse, IL-4 significantly suppressed the ICOS-enhancing effects of IL-12 and IL-23. The functional consequence of variable ICOS levels was shown in coculture experiments with cells expressing the ICOS-ligand B7-related protein 1 (either transfected Chinese hamster ovary cells or autologous dendritic cells). Ligation of ICOS on 2-day-preactivated effector cells increased their cytokine production to an extent proportional to their ICOS expression levels. As the ICOS-enhancing potentials of IL-12 and IL-23 were maintained for several days after stimulation, both on Th1 and Th2 cells, we propose the concept that local regulation of ICOS expression on activated Th cells by IL-12 and/or IL-23 may provide a powerful means to amplify effector T cell responses in peripheral tissues, independently of the polarized state of the Th cells.
Direct Measurement of T Cell Subset Kinetics In Vivo in Elderly Men and Women
Authors: Wallace Diana L. , Zhang Yan , Ghattas Hala , Worth Andrew , Irvine Andrew , Bennett Andrea R. , Griffin George E. , Beverley Peter C. L. , Tough David F. , Macallan Derek C. 
Published: April 2014

Abstract
The age-associated decline in immunocompetence is paralleled by changes in the proportions of PBL subpopulations. In turn, the size and composition of the peripheral lymphocyte pool is determined by input from the thymus and bone marrow and by the balance of proliferation and death in each lymphocyte subpopulation. We compared the kinetics of lymphocyte subtypes in young (seven of eight CMV seronegative) and healthy elderly human subjects (six of seven CMV seropositive), using deuterated glucose DNA labeling in vivo to measure rates of T cell proliferation and disappearance. For CD45RO+ cells of both CD4+ and CD8+ subtypes and for CD4+CD45RA+ cells the kinetics of proliferation and disappearance were remarkably similar between elderly and young subjects. In the young, the kinetics of CD8+CD45RA+ cells with a naive phenotype resembled those of CD4+CD45RA+ cells. However, CD8+CD45RA+ T cells from the elderly exhibited a predominantly primed phenotype, and for this subset, although the proliferation rate was similar to that of other CD45RA+ cells, the disappearance rate of labeled cells was greatly decreased compared with that of all other T cell subsets. Our data provide a direct demonstration that there are no substantial changes in in vivo kinetics for most T cell populations in healthy elderly compared with young subjects. However, primed CD8+CD45RA+ cells show unusual kinetic properties, indicating the persistence of these cells in the blood and dissociation of proliferation from disappearance.
T Cell Immunity to Type II Collagen in the Biobreeding Rat: The Identification and Characterization of RT1u-Restricted T Cell Epitopes on α1(II)
Authors: Cremer Michael A. , Ye Xiu J. , Myers Linda K. , Brand David D. , Rosloniec Edward F. , Kang Andrew H. 
Published: April 2014

Abstract
Susceptibility to experimental collagen-induced arthritis in rodents is dependent on MHC class II elements to bind peptides from the type II collagen (CII) molecule. Although a substantial body of data has been reported in mice defining these peptide Ags, little has been reported in rats. In this study, we investigate the locations and sequences of CII peptides, which are bound by RT1u molecules, expressed by diabetic-resistant, arthritis-susceptible Biobreeding rats, and, in turn, stimulate CII-specific T cells. By using overlapping and substituted peptide homologues of CII, we have identified and characterized an immunodominant and five subdominant epitopes on CII, which stimulate RT1u-restricted T cell proliferation. The immunodominant epitope, CII (186–192), contains a QGPRG core sequence, which was found in a subdominant epitope CII (906–916). Similar sequences containing single conservative substitutions were identified in three other epitopes. One, CII (263–272), contained a conservatively substituted R→K substitution, whereas CII (880–889) and CII (906–916) contained nonconservative substitutions, i.e., P→D and R→M, respectively. Homologue peptides containing these sequences stimulated T cell proliferative responses, although less intensely than peptides containing CII (186–192). Substituting QGR residues in the QGPRG core with alanine, isoleucine, or proline reduced proliferation, as did substituting flanking E and G residues at the N terminus and E at the C terminus. Collectively, these data indicate that RT1u-restricted immunodominant and several subdominant epitopes on CII often share a QGPRG-like motif, with conservative substitutions present at either P or R positions. This motif is similar to one recognized by collagen-induced arthritis-susceptible HLA-DR1- and HLA-DR4-transgenic mice.
Cyclic Adenosine 5′-Monophosphate Response Element Binding Protein Plays a Central Role in Mediating Proliferation and Differentiation Downstream of the Pre-TCR Complex in Developing Thymocytes
Authors: Grady Gillian C. , Mason Susan M. , Stephen Jillian , Zúñiga-Pflücker Juan Carlos , Michie Alison M. 
Published: April 2014

Abstract
The roles played by specific transcription factors during the regulation of early T cell development remain largely undefined. Several key genes induced during the primary checkpoint of T cell development, β-selection, contain cAMP response element sites within their enhancer-promoter region that are regulated by CREB activation. In this study, we show that CREB is constitutively phosphorylated in the thymus, but not the spleen. We also show that CREB is activated downstream of the pre-TCR complex, and that the induction of CREB activity is regulated by protein kinase Cα- and ERK-MAPK-mediated signals. We addressed the importance of this activation by expressing a naturally occurring inhibitor of CREB, inducible cAMP early repressor in wild-type fetal liver-derived lymphoid progenitor cells, and assessed their developmental potential. Fetal thymic organ cultures reconstituted with cells constitutively expressing inducible cAMP early repressor displayed a delay in generating CD4+CD8+ thymocytes and a decrease in cellularity compared with control fetal thymic organ cultures. Taken together, our studies establish that CREB plays a central role in relaying proliferation and differentiation signals from the pre-TCR complex into the nucleus in developing thymocytes.
MHC Class I-Independent Recognition of NK-Activating Receptor KIR2DS4
Authors: Katz Gil , Gazit Roi , Arnon Tal I. , Gonen-Gross Tsufit , Tarcic Gabi , Markel Gal , Gruda Raizy , Achdout Hagit , Drize Olga , Merims Sharon , Mandelboim Ofer 
Published: April 2014

Abstract
Natural killer cells are capable of killing tumor and virus-infected cells. This killing is mediated primarily via the natural cytotoxicity receptors, including NKp46, NKp44, NKp30, and by the NKG2D receptor. Killer cell Ig-like receptors (KIRs) are mainly involved in inhibiting NK killing (inhibitory KIRs) via interaction with MHC class I molecules. Some KIRs, however, have been found to enhance NK killing when interacting with MHC class I molecules (activating KIRs). We have previously demonstrated that KIR2DS4, an activating KIR, recognizes the HLA-Cw4 protein. The interaction observed was weak and highly restricted to HLA-Cw4 only. These findings prompted us to check whether KIR2DS4 might have additional ligand(s). In this study, we show that KIR2DS4 is able to also interact with a non-class I MHC protein expressed on melanoma cell lines and on a primary melanoma. This interaction is shown to be both specific and functional. Importantly, site-directed mutagenesis analysis reveals that the amino acid residues involved in the recognition of this novel ligand are different from those interacting with HLA-Cw4. These results may shed new light on the function of activating KIRs and their relevance in NK biology.