bluuebunny/crossref_metadata_2025_split huggingface dataset:
Functional Implication of Cellular Prion Protein in Antigen-Driven Interactions between T Cells and Dendritic Cells
Authors: Ballerini Clara , Gourdain Pauline , Bachy Véronique , Blanchard Nicolas , Levavasseur Etienne , Grégoire Sylvie , Fontes Pascaline , Aucouturier Pierre , Hivroz Claire , Carnaud Claude 
Published: April 2014

Abstract
The cellular prion protein (PrPC) is a host-encoded, GPI-anchored cell surface protein, expressed on a wide range of tissues including neuronal and lymphoreticular cells. PrPC may undergo posttranslational conversion, giving rise to scrapie PrP, the pathogenic conformer considered as responsible for prion diseases. Despite intensive studies, the normal function of PrPC is still enigmatic. Starting from microscope observations showing an accumulation of PrPC at the sites of contact between T cells and Ag-loaded dendritic cells (DC), we have studied the contribution of PrPC in alloantigen and peptide-MHC-driven T/DC interactions. Whereas the absence of PrPC on the DC results in a reduced allogeneic T cell response, its absence on the T cell partner has no apparent effect upon this response. Therefore, PrPC seems to fulfill different functions on the two cell partners forming the synapse. In contrast, PrPC mobilization by Ab reduces the stimulatory properties of DC and the proliferative potential of responding T cells. The contrasted consequences, regarding T cell function, between PrPC deletion and PrPC coating by Abs, suggests that the prion protein acts as a signaling molecule on T cells. Furthermore, our results show that the absence of PrPC has consequences in vivo also, upon the ability of APCs to stimulate proliferative T cell responses. Thus, independent of neurological considerations, some of the evolutionary constraints that may have contributed to the conservation of the Prnp gene in mammalians, could be of immunological origin.
CARMA1 Is Critical for the Development of Allergic Airway Inflammation in a Murine Model of Asthma
Authors: Medoff Benjamin D. , Seed Brian , Jackobek Ryan , Zora Jennifer , Yang Yi , Luster Andrew D. , Xavier Ramnik 
Published: April 2014

AbstractCARMA1 has been shown to be important for Ag-stimulated activation of NF-κB in lymphocytes in vitro and thus could be a novel therapeutic target in inflammatory diseases such as asthma. In the present study, we demonstrate that mice with deletion in the CARMA1 gene (CARMA1−/−) do not develop inflammation in a murine model of asthma. Compared with wild-type controls, CARMA1−/− mice did not develop airway eosinophilia, had no significant T cell recruitment into the airways, and had no evidence for T cell activation in the lung or draining lymph nodes. In addition, the CARMA1−/− mice had significantly decreased levels of IL-4, IL-5, and IL-13, did not produce IgE, and did not develop airway hyperresponsiveness or mucus cell hypertrophy. However, adoptive transfer of wild-type Th2 cells into CARMA1−/− mice restored eosinophilic airway inflammation, cytokine production, airway hyperresponsiveness, and mucus production. This is the first demonstration of an in vivo role for CARMA1 in a disease process. Furthermore, the data clearly show that CARMA1 is essential for the development of allergic airway inflammation through its role in T lymphocytes, and may provide a novel means to inhibit NF-κB for therapy in asthma.
IL-1β Breaks Tolerance through Expansion of CD25+ Effector T Cells
Authors: O’Sullivan Brendan J. , Thomas Helen E. , Pai Saparna , Santamaria Pere , Iwakura Yoichiro , Steptoe Raymond J. , Kay Thomas W. H. , Thomas Ranjeny 
Published: April 2014

Abstract
IL-1 is a key proinflammatory driver of several autoimmune diseases including juvenile inflammatory arthritis, diseases with mutations in the NALP/cryopyrin complex and Crohn’s disease, and is genetically or clinically associated with many others. IL-1 is a pleiotropic proinflammatory cytokine; however the mechanisms by which increased IL-1 signaling promotes autoreactive T cell activity are not clear. Here we show that autoimmune-prone NOD and IL-1 receptor antagonist-deficient C57BL/6 mice both produce high levels of IL-1, which drives autoreactive effector cell expansion. IL-1β drives proliferation and cytokine production by CD4+CD25+FoxP3− effector/memory T cells, attenuates CD4+CD25+FoxP3+ regulatory T cell function, and allows escape of CD4+CD25− autoreactive effectors from suppression. Thus, inflammation or constitutive overexpression of IL-1β in a genetically predisposed host can promote autoreactive effector T cell expansion and function, which attenuates the ability of regulatory T cells to maintain tolerance to self.
Oxygen Radicals Induce Poly(ADP-Ribose) Polymerase-Dependent Cell Death in Cytotoxic Lymphocytes
Authors: Thorén Fredrik B. , Romero Ana I. , Hellstrand Kristoffer 
Published: April 2014

AbstractCytotoxic T cells and NK cells will acquire features of apoptosis when exposed to oxygen radicals, but the molecular mechanisms underlying this phenomenon are incompletely understood. We have investigated the role of two enzyme systems responsible for execution of cell death, caspases and the poly(ADP-ribose) polymerase (PARP). We report that although human cytotoxic lymphocytes were only marginally protected by caspase inhibitors, PARP inhibitors completely protected lymphocytes from radical-induced apoptosis and restored their cytotoxic function. The radical-induced, PARP-dependent cell death was accompanied by nuclear accumulation of apoptosis-inducing factor and a characteristic pattern of large-fragment DNA degradation. It is concluded that the PARP/apoptosis-inducing factor axis is critically involved in oxygen radical-induced apoptosis in cytotoxic lymphocytes.
Quantifying and Imaging NY-ESO-1/LAGE-1-Derived Epitopes on Tumor Cells Using High Affinity T Cell Receptors
Authors: Purbhoo Marco A. , Sutton Deborah H. , Brewer Joanna E. , Mullings Rebecca E. , Hill Maxine E. , Mahon Tara M. , Karbach Julia , Jäger Elke , Cameron Brian J. , Lissin Nikolai , Vyas Paresh , Chen Ji-Li , Cerundolo Vincenzo , Jakobsen Bent K. 
Published: April 2014

AbstractPresentation of intracellular tumor-associated Ags (TAAs) in the context of HLA class I molecules offers unique cancer-specific cell surface markers for the identification and targeting of tumor cells. For most peptide Ags, the levels of and variations in cell surface presentation remain unknown, yet these parameters are of crucial importance when considering specific TAAs as targets for anticancer therapy. Here we use a soluble TCR with picomolar affinity for the HLA-A2-restricted 157–165 epitope of the NY-ESO-1 and LAGE-1 TAAs to investigate presentation of this immunodominant epitope on the surface of a variety of cancer cells. By single molecule fluorescence microscopy, we directly visualize HLA-peptide presentation for the first time, demonstrating that NY-ESO-1/LAGE-1-positive tumor cells present 10–50 NY-ESO-1/LAGE-1157–165 epitopes per cell.
Efficient Immunization and Cross-Priming by Vaccine Adjuvants Containing TLR3 or TLR9 Agonists Complexed to Cationic Liposomes
Authors: Zaks Karen , Jordan Michael , Guth Amanda , Sellins Karen , Kedl Ross , Izzo Angelo , Bosio Catharine , Dow Steven 
Published: April 2014

AbstractComplexing TLR9 agonists such as plasmid DNA to cationic liposomes markedly potentiates their ability to activate innate immunity. We therefore reasoned that liposomes complexed with DNA or other TLR agonists could be used as effective vaccine adjuvants. To test this hypothesis, the vaccine adjuvant effects of liposomes complexed to TLR agonists were assessed in mice. We found that liposomes complexed to nucleic acids (liposome-Ag-nucleic acid complexes; LANAC) were particularly effective adjuvants for eliciting CD4+ and CD8+ T cell responses against peptide and protein Ags. Notably, LANAC containing TLR3 or TLR9 agonists effectively cross-primed CD8+ T cell responses against even low doses of protein Ags, and this effect was independent of CD4+ T cell help. Ag-specific CD8+ T cells elicited by LANAC adjuvants were functionally active and persisted for long periods of time in tissues. In a therapeutic tumor vaccine model, immunization with the melanoma peptide trp2 and LANAC adjuvant controlled the growth of established B16 melanoma tumors. In a prophylactic vaccine model, immunization with the Mycobacterium tuberculosis protein ESAT-6 with LANAC adjuvant elicited significant protective immunity against aerosol challenge with virulent M. tuberculosis. These results suggest that certain TLR agonists can be combined with cationic liposomes to produce uniquely effective vaccine adjuvants capable of eliciting strong T cell responses against protein and peptide Ags.
The Cyclic AMP-Epac1-Rap1 Pathway Is Dissociated from Regulation of Effector Functions in Monocytes but Acquires Immunoregulatory Function in Mature Macrophages
Authors: Bryn Tone , Mahic Milada , Enserink Jorrit M. , Schwede Frank , Aandahl Einar Martin , Taskén Kjetil 
Published: April 2014

AbstractcAMP mediates its intracellular effects through activation of protein kinase A (PKA), nucleotide-gated ion channels, or exchange protein directly activated by cAMP (Epac). Although elevation of cAMP in lymphocytes leads to suppression of immune functions by a PKA-dependent mechanism, the effector mechanisms for cAMP regulation of immune functions in monocytes and macrophages are not fully understood. In this study, we demonstrate the presence of Epac1 in human peripheral blood monocytes and activation of Rap1 in response to cAMP. However, by using an Epac-specific cAMP analog (8-CPT-2′-O-Me-cAMP), we show that monocyte activation parameters such as synthesis and release of cytokines, stimulation of cell adhesion, chemotaxis, phagocytosis, and respiratory burst are not regulated by the Epac1-Rap1 pathway. In contrast, activation of PKA by a PKA-specific compound (6-Bnz-cAMP) or physiological cAMP-elevating stimuli like PGE2 inhibits monocyte immune functions. Furthermore, we show that the level of Epac1 increases 3-fold during differentiation of monocytes into macrophages, and in monocyte-derived macrophages cAMP inhibits FcR-mediated phagocytosis via both PKA and the Epac1-Rap1 pathway. However, LPS-induced TNF-α production is only inhibited through the PKA pathway in these cells. In conclusion, the Epac1-Rap1 pathway is present in both monocytes and macrophages, but only regulates specific immune effector functions in macrophages.
Estrogen Induces Thymic Atrophy by Eliminating Early Thymic Progenitors and Inhibiting Proliferation of β-Selected Thymocytes
Authors: Zoller Allison L. , Kersh Gilbert J. 
Published: April 2014

AbstractAlthough it has been established that high levels of estrogen can induce thymic involution, the mechanism by which this happens is not known. We have found that daily i.p. injections of the synthetic estrogen 17-β-estradiol reduce thymus cellularity by 80% over a period of 4–6 days. Although the atrophy is most strikingly observed in the CD4/CD8 double-positive (DP) thymic subset, the loss of thymocytes is not accompanied by a significant increase in thymocyte apoptosis, suggesting that direct killing of cells may not be the dominant means by which estrogens induce thymic atrophy. Instead, we find that estradiol drastically reduces the lineage-negative, Flt3+Sca-1+c-Kit+ population in the bone marrow, a population that contains thymic homing progenitors. Within the thymus, we observe that estradiol treatment results in a preferential depletion of early thymic progenitors. In addition, we find that estradiol leads to a significant reduction in the proliferation of thymocytes responding to pre-TCR signals. Reduced proliferation of DN3 and DN4 cell subsets is likely the major contributor to the reduction in DP thymocytes that is observed. The reduction in early thymic progenitors is also likely to contribute to thymic atrophy, as we show that estradiol treatment can reduce the size of Rag1-deficient thymuses, which lack pre-TCR signals and DP thymocytes.
CD4+ T Cells Can Protect APC from CTL-Mediated Elimination
Authors: Mueller Scott N. , Jones Claerwen M. , Stock Angus T. , Suter Mark , Heath William R. , Carbone Francis R. 
Published: April 2014

AbstractProfessional APC play a central role in generating antiviral CD8+ CTL immunity. However, the fate of such APC following interaction with these same CTL remains poorly understood. We have shown previously that prolonged Ag presentation persists in the presence of a strong CTL response following HSV infection. In this study, we examined the mechanism of survival of APC in vivo when presenting an immunodominant determinant from HSV. We show that transferred peptide-labeled dendritic cells were eliminated from draining lymph nodes in the presence of HSV-specific CTL. Maturation of dendritic cells with LPS or anti-CD40 before injection protected against CTL lysis in vivo. Furthermore, endogenous APC could be eliminated from draining lymph nodes early after HSV infection by adoptive transfer of HSV-specific CTL, yet the cotransfer of significant virus-specific CD4+ T cell help promoted prolonged Ag presentation. This suggests that Th cells may assist in prolonging class I-restricted Ag presentation, potentially enhancing CTL recruitment and allowing more efficient T cell priming.
A Membrane Form of TNF-α Presented by Exosomes Delays T Cell Activation-Induced Cell Death
Authors: Zhang Huang-Ge , Liu Cunren , Su Kaihun , Yu Shaohua , Zhang Liming , Zhang Shuangqin , Wang Jianhua , Cao Xu , Grizzle William , Kimberly Robert P. 
Published: April 2014

AbstractIn common with many other cell types, synovial fibroblasts produce exosomes. In this study, we show that the exosomes produced by synovial fibroblasts obtained from individuals with rheumatoid arthritis (RASF), but not exosomes produced by synovial fibroblasts obtained from individuals with osteoarthritis, contain a membrane bound form of TNF-α as demonstrated by colloidal gold immunostaining of TNF-α and confirmed by both Western blot and mass spectrometry. The RASF-derived exosomes, but not exosomes derived from fibroblasts obtained from individuals with osteoarthritis, are cytotoxic for the L929 cell, a TNF-α-sensitive cell line, and stimulate activation of NF-κB and induction of collagenase-1 in RASF. These effects are blocked by addition of soluble TNFR1 (sTNFbp), suggesting that a TNF-α-signaling pathway mediates these biological activities. sTNFbp also reduced the production of exosomes by RASF, suggesting the interruption of a positive amplification loop. Exosomes can transmit signals between cells, and RASF exosomes, effectively taken up by anti-CD3-activated T cells, activated AKT and NF-κB and rendered these activated T cells resistant to apoptosis. Neutralization of exosomal membrane TNF-α by sTNFbp partially reversed this resistance, suggesting that not only TNF-α but also additional exosomal proteins may contribute to the development of apoptosis resistance.
Signals from a Self-Antigen Induce Positive Selection in Early B Cell Ontogeny but Are Tolerogenic in Adults
Authors: Ferry Helen , Crockford Tanya L. , Leung Janson C. H. , Cornall Richard J. 
Published: April 2014

AbstractPositive and negative signals from self-Ags shape the B cell repertoire and the development of distinct B cell subsets, but little is known about what distinguishes these signals. To address this question, we have studied the development of anti-hen egg lysozyme MD4 Ig transgene B cells while systematically varying the level, distribution, and timing of exposure to different forms of hen egg lysozyme as a self-Ag. This process has allowed us to explore the effects of Ag independent of BCR specificity. Our findings show how the selection of autoreactive B cells is a competitive process involving immunogenic and tolerogenic forms of self-Ags. Due to a developmental switch during B cell ontogeny, autoreactive anti-hen egg lysozyme MD4 Ig transgene B cells are negatively selected by self-Ags in adult bone marrow but susceptible to positive selection by some of the same self-Ags in fetal and neonatal life. However, the persistence of B1 cells and IgM autoantibodies from early ontogeny enables autoreactive B cells from the adult bone marrow to escape negative selection. Our data suggest that this rescue may be due to the clearance or masking of self-Ag by IgM autoantibody. We discuss the implications of these findings in terms of B cell selection and the maintenance of self-tolerance during early and adult life.
IL-4 Receptor α Is an Important Modulator of IL-4 and IL-13 Receptor Binding: Implications for the Development of Therapeutic Targets
Authors: Andrews Allison-Lynn , Holloway John W. , Holgate Stephen T. , Davies Donna E. 
Published: April 2014

AbstractIL-4 is a key cytokine associated with allergy and asthma. Induction of cell signaling by IL-4 involves interaction with its cognate receptors, a complex of IL-4Rα with either the common γ-chain or the IL-13R chain α1 (IL-13Rα1). We found that IL-4 bound to the extracellular domain of IL-4Rα (soluble human (sh)IL-4Rα) with high affinity and specificity. In contrast with the sequential mechanism of binding and stabilization afforded by IL-4Rα to the binding of IL-13 to IL-13Rα1, neither common γ-chain nor IL-13Rα1 contributed significantly to the stabilization of the IL-4:IL-4Rα complex. Based on the different mechanisms of binding and stabilization of the IL-4R and IL-13R complexes, we compared the effects of shIL-4Rα and an IL-4 double mutein (R121D/Y124D, IL-4R antagonist) on IL-4- and IL-13-mediated responses. Whereas IL-4R antagonist blocked responses to both cytokines, shIL-4Rα only blocked IL-4. However, shIL-4Rα stabilized and augmented IL-13-mediated STAT6 activation and eotaxin production by primary human bronchial fibroblasts at suboptimal doses of IL-13. These data demonstrate that IL-4Rα plays a key role in the binding affinity of both IL-13R and IL-4R complexes. Under certain conditions, shIL-4Rα has the potential to stabilize binding IL-13 to its receptor to augment IL-13-mediated responses. Thus, complete understanding of the binding interactions between IL-4 and IL-13 and their cognate receptors may facilitate development of novel treatments for asthma that selectively target these cytokines without unpredicted or detrimental side effects.
The HIV-Neutralizing Monoclonal Antibody 4E10 Recognizes N-Terminal Sequences on the Native Antigen
Authors: Hager-Braun Christine , Katinger Hermann , Tomer Kenneth B. 
Published: April 2014

Abstract
Characterization of the epitope recognized by the broadly neutralizing anti-HIV Ab 4E10 has, heretofore, focused on a linear sequence from the gp41 pretransmembrane region (PTMR). Attempts to generate neutralizing Abs based on this linear epitope sequence have been unsuccessful. We have characterized the antigenic determinants on recombinant glycosylated full-length Ags, and nonglycosylated and truncated Ags recognized by 4E10 using epitope extraction and excision assays in conjunction with MALDI mass spectrometry. The mAb recognized the peptides 34LWVTVYYGVPVWK46 and 512AVGIGAVFLGFLGAAGSTMGAASMTLTVQAR542 located at the N-terminal region of gp120 and gp41, respectively. Immunoassays verified AV(L/M)FLGFLGAA as the gp41 epitope core. Recognition of the peptide from the gp41 PTMR was detected only in constructs in which the N termini of the mature envelope proteins were missing. In this region, the epitope core is located in the sequence 672WFDITNWLWY681. We hypothesize that the hydrophobic surface of the paratope functions as a “trap” for the viral sequences, which are responsible for insertion into the host cell membrane. As the N-terminal region of gp120, the fusogenic peptide of gp41, and the PTMR of gp41 show high sequence homology among various HIV strains, this model is consistent with the broadly neutralizing capabilities of 4E10.
The Double Lysine Motif of Tapasin Is a Retrieval Signal for Retention of Unstable MHC Class I Molecules in the Endoplasmic Reticulum
Authors: Paulsson Kajsa M. , Jevon Marc , Wang James W. , Li Suling , Wang Ping 
Published: April 2014

Abstract
Tapasin (tpn), an essential component of the MHC class I (MHC I) loading complex, has a canonical double lysine motif acting as a retrieval signal, which mediates retrograde transport of escaped endoplasmic reticulum (ER) proteins from the Golgi back to the ER. In this study, we mutated tpn with a substitution of the double lysine motif to double alanine (GFP-tpn-aa). This mutation abolished interaction with the coatomer protein complex I coatomer and resulted in accumulation of GFP-tpn-aa in the Golgi compartment, suggesting that the double lysine is important for the retrograde transport of tpn from late secretory compartments to the ER. In association with the increased Golgi distribution, the amount of MHC I exported from the ER to the surface was increased in 721.220 cells transfected with GFP-tpn-aa. However, the expressed MHC I were less stable and had increased turnover rate. Our results suggest that tpn with intact double lysine retrieval signal regulates retrograde transport of unstable MHC I molecules from the Golgi back to the ER to control the quality of MHC I Ag presentation.
Alteration of the FcγRIIa Dimer Interface Affects Receptor Signaling but Not Ligand Binding
Authors: Powell Maree S. , Barnes Nadine C. , Bradford Tessa M. , Musgrave Ian F. , Wines Bruce D. , Cambier John C. , Hogarth P. Mark 
Published: April 2014

Abstract
The aggregation of cell surface FcRs by immune complexes induces a number of important Ab-dependent effector functions. However, despite numerous studies that examine receptor function, very little is known about the molecular organization of these receptors within the cell. In this study, protein complementation, mutagenesis, and ligand binding analyses demonstrate that human FcγRIIa is present as a noncovalent dimer form. Protein complementation studies found that FcγRIIa molecules are closely associated. Mutagenesis of the dimer interface, as identified by crystallographic analyses, did not affect ligand binding yet caused significant alteration to the magnitude and kinetics of receptor phosphorylation. The data suggest that the ligand binding and the dimer interface are distinct regions within the receptor, and noncovalent dimerization of FcγRIIa may be an essential feature of the FcγRIIa signaling cascade.
Level of Expression of IL-13Rα2 Impacts Receptor Distribution and IL-13 Signaling
Authors: Daines Michael O. , Tabata Yasuhiro , Walker Bradley A. , Chen Weiguo , Warrier Manoj R. , Basu Saswata , Hershey Gurjit K. Khurana 
Published: April 2014

AbstractIL-13, a critical cytokine for allergic inflammation, exerts its effects through a complex receptor system including IL-4Rα, IL-13Rα1, and IL-13Rα2. IL-4Rα and IL-13Rα1 form a heterodimeric signaling receptor for IL-13. In contrast, IL-13Rα2 binds IL-13 with high affinity but does not signal. IL-13Rα2 exists on the cell surface, intracellularly, and in soluble form, but no information is available regarding the relative distributions of IL-13Rα2 among these compartments, whether the compartments communicate, and how the relative expression levels impact IL-13 responses. Herein, we investigated the distribution of IL-13Rα2 in transfected and primary cells, and we evaluated how the total level of IL-13Rα2 expression impacted its distribution. Our results demonstrate that the distribution of IL-13Rα2 is independent of the overall level of expression. The majority of the IL-13Rα2 protein existed in intracellular pools. Surface IL-13Rα2 was continually released into the medium in a soluble form, yet surface expression remained constant supporting receptor trafficking to the cell surface. IL-13Rα2 inhibited IL-13 signaling proportionally to its level of expression, and this inhibition could be overcome with high concentrations of IL-13.