bluuebunny/crossref_metadata_2025_split huggingface dataset:
Suppression of Granulocyte-Macrophage Colony-Stimulating Factor Expression by Glucocorticoids Involves Inhibition of Enhancer Function by the Glucocorticoid Receptor Binding to Composite NF-AT/Activator Protein-1 Elements
Authors: Smith Philip J. , Cousins David J. , Jee Young-Koo , Staynov Dontcho Z. , Lee Tak H. , Lavender Paul 
Published: April 2014

AbstractIncreased expression of a number of cytokines including GM-CSF is associated with chronic inflammatory conditions such as bronchial asthma. Glucocorticoid therapy results in suppression of cytokine levels by a mechanism(s) not yet fully understood. We have examined regulation of GM-CSF expression by the synthetic glucocorticoid dexamethasone in human T cells. Transient transfection assays with reporter constructs revealed that dexamethasone inhibited the function of the GM-CSF enhancer, but had no effect on regulation of GM-CSF expression occurring through the proximal promoter. Activation of the GM-CSF enhancer involves cooperative interaction between the transcription factors NF-AT and AP-1. We demonstrate here that glucocorticoid-mediated inhibition of enhancer function involves glucocorticoid receptor (GR) binding to the NF-AT/AP-1 sites. These elements, which do not constitute recognizable glucocorticoid response elements, support binding of the GR, primarily as a dimer. This binding correlates with the ability of dexamethasone to inhibit enhancer activity of the NF-AT/AP-1 elements, suggesting a competition between NF-AT/AP-1 proteins and GR.
Expression of α4β7 Integrin Defines a Distinct Pathway of Lymphoid Progenitors Committed to T Cells, Fetal Intestinal Lymphotoxin Producer, NK, and Dendritic Cells
Authors: Yoshida Hisahiro , Kawamoto Hiroshi , Santee Sybil M. , Hashi Hiroyuki , Honda Kenya , Nishikawa Satomi , Ware Carl F. , Katsura Yoshimoto , Nishikawa Shin-Ichi 
Published: April 2014

AbstractDuring embryogenesis, the Peyer’s patch anlagen are induced by a cell population that produces lymphotoxin (LT) α1β2 following stimulation of IL-7Rα. In this study, we show that the LT-producing cell is localized within the IL-7Rα+ and integrin α4β7 (α4β7)+ population in the embryonic intestine. Lineage commitment to the LT producer phenotype in the fetal liver coincides with expression of α4β7. Before expression of α4β7, the potential of IL-7Rα+ population to generate B cells is lost. However, the progenitors for T cells and LT producer cells reside in the IL-7Rα+α4β7+ cells, but during subsequent differentiation, the potential to give rise to T cells is lost. This IL-7Rα+α4β7+ population migrates to the intestine, where it induces the Peyer’s patch anlagen. When stimulated with IL-15 or IL-3 and TNF, the intestinal IL-7Rα+α4β7+ population can differentiate into fully competent NK1.1+ NK cells or CD11c+ APCs. Expression of α4β7 is lost during differentiation of both lineages; IL-7Rα expression is lost during NK1.1+ cells differentiation. A newly discovered lineage−IL-7Rα+c-Kit+α4β7+ population in the fetal liver is committed to T, NK, dendritic, and fetal intestinal LT producer lineage, the latter being an intermediate stage during differentiation of NK and dendritic cells.
Longevity of Antigen Presentation and Activation Status of APC Are Decisive Factors in the Balance Between CTL Immunity Versus Tolerance
Authors: Th. den Boer Annemieke , Diehl Linda , van Mierlo Geertje J. D. , van der Voort Ellen I. H. , Fransen Marieke F. , Krimpenfort Paul , Melief Cornelis J. M. , Offringa Rienk , Toes René E. M. 
Published: April 2014

AbstractEncounter of Ag by naive T cells can lead to T cell priming as well as tolerance. The balance between immunity and tolerance is controlled by the conditions of Ag encounter and the activation status of the APC. We have investigated the rules that govern this balance in case an environment that normally induces tolerance is reverted into a milieu that promotes T cell priming, using a minimal CTL epitope derived from human adenovirus type 5 E1A. Vaccination of mice s.c. with E1A peptide in IFA readily induces CTL tolerance, resulting in the inability to control E1A-expressing tumors. The present study shows that efficient CTL priming is achieved when this peptide vaccine is combined with systemic administration of APC-activating compounds like agonistic anti-CD40 mAb or polyriboinosinate-polyribocytidylate. Surprisingly, this CTL response is not long-lasting and therefore fails to protect against tumor outgrowth. Disappearance of CTL reactivity was strongly associated with systemic persistence of the peptide for &gt;200 days. In contrast, peptide administered in PBS does not persist and generates long term CTL immunity capable of rejecting Ad5E1A-positive tumors, when combined with CD40 triggering. Thus, presentation of CTL epitopes in an appropriate costimulatory setting by activated APC, although being essential and sufficient for CTL priming, eventually results in tolerance when the Ag persists systemically for prolonged times. These observations are important for the development of immune intervention schemes in autoimmunity and cancer.
Exogenous Peptides Presented by Transporter Associated with Antigen Processing (TAP)-Deficient and TAP-Competent Cells: Intracellular Loading and Kinetics of Presentation
Authors: Luft Thomas , Rizkalla Mark , Tai Tsin Yee , Chen Qiyuan , MacFarlan Roderick I. , Davis Ian D. , Maraskovsky Eugene , Cebon Jonathan 
Published: April 2014

AbstractThis study investigates the differential capacity of TAP-deficient T2 cells, TAP-competent EBV cells, and immature and mature dendritic cells to present peptides to preformed CTL lines. It demonstrates that presentation of exogenous peptides involves peptide uptake and loading onto newly synthesized MHC class I molecules. This mechanism was best demonstrated for low affinity peptides in the presence of irrelevant peptides competing for HLA binding sites. Under these circumstances, inhibition of protein synthesis with cycloheximide or vesicular trafficking with brefeldin A significantly reduced the presentation of low affinity peptides. This was not restored by adding exogenous β2-microglobulin to stabilize the MHC complex on the cell surface. In contrast, presentation of high affinity peptides was not sensitive to cycloheximide or brefeldin A, which suggests that different mechanisms may operate for presentation of high and low affinity peptides by TAP-competent cells. High affinity peptides can apparently compete with peptides in preloaded MHC class I molecules at the cell surface, whereas low affinity peptides require empty MHC molecules within cells. Accordingly, very high concentrations of exogenous low affinity peptides in conjunction with active MHC class I metabolism were required to allow successful presentation against a background of competing intracellular high affinity peptides in TAP-competent cells. These findings have implications for the design of peptide and protein-based vaccines.
Neutrophils Process Exogenous Bacteria Via an Alternate Class I MHC Processing Pathway for Presentation of Peptides to T Lymphocytes
Authors: Potter Nicholas S. , Harding Clifford V. 
Published: April 2014

AbstractPeptides that are presented by class I MHC (MHC-I) molecules derive from cytosolic Ags processed via the conventional MHC-I pathway or exogenous Ags processed via alternate MHC-I processing mechanisms. Alternate MHC-I processing by macrophages and dendritic cells allows presentation of peptides from particulate Ags, including bacteria. Despite the established phagocytic activity of neutrophils, MHC-I processing and presentation of phagocytosed Ags by neutrophils has not been investigated. Murine neutrophils from peritoneal exudates were shown to express MHC-I molecules and tested for the ability to process HB101.Crl-OVA, Escherichia coli transfected to express a fusion protein containing the 257–264 epitope of OVA. Neutrophils were found to process HB101.Crl-OVA and present OVA257–264-Kb complexes to CD8OVA T hybridoma cells via a pathway that was resistant to brefeldin A, an inhibitor of anterograde endoplasmic reticulum-Golgi transport, and lactacystin, a proteasome inhibitor. These results suggest that neutrophils process phagocytosed bacteria via a vacuolar alternate MHC-I pathway that does not involve cytosolic processing. In addition, neutrophils were found to secrete or “regurgitate” processed peptide that was subsequently presented by neighboring prefixed macrophages or dendritic cells. Thus, neutrophils may influence T cell responses to bacteria, either by directly presenting peptide-MHC-I complexes or by delivering peptides to other APCs for presentation. Hypothetically, neutrophils may directly present peptide to effector T cells in vivo at sites of inflammation, inducing cytokine production, whereas dendritic cells in receipt of neutrophil-derived antigenic peptides may migrate to lymphoid organs to initiate T cell responses.
Bidirectional Negative Regulation of Human T and Dendritic Cells by CD47 and Its Cognate Receptor Signal-Regulator Protein-α: Down-Regulation of IL-12 Responsiveness and Inhibition of Dendritic Cell Activation
Authors: Latour Sylvain , Tanaka Hiroyuki , Demeure Christian , Mateo Véronique , Rubio Manuel , Brown Eric J. , Maliszewski Charles , Lindberg Frederik P. , Oldenborg Anna , Ullrich Axel , Delespesse Guy , Sarfati Marika 
Published: April 2014

AbstractProinflammatory molecules, including IFN-γ and IL-12, play a crucial role in the elimination of causative agents. To allow healing, potent anti-inflammatory processes are required to down-regulate the inflammatory response. In this study, we first show that CD47/integrin-associated protein, a ubiquitous multispan transmembrane protein highly expressed on T cells, interacts with signal-regulator protein (SIRP)-α, an immunoreceptor tyrosine-based inhibition motif-containing molecule selectively expressed on myelomonocytic cells, and next demonstrate that this pair of molecules negatively regulates human T and dendritic cell (DC) function. CD47 ligation by CD47 mAb or L-SIRP-α transfectants inhibits IL-12R expression and down-regulates IL-12 responsiveness of activated CD4+ and CD8+ adult T cells without affecting their response to IL-2. Human CD47-Fc fusion protein binds SIRP-α expressed on immature DC and mature DC. SIRP-α engagement by CD47-Fc prevents the phenotypic and functional maturation of immature DC and still inhibits cytokine production by mature DC. Finally, in allogeneic MLR between mDC and naive T cells, CD47-Fc decreases IFN-γ production after priming and impairs the development of a Th1 response. Therefore, CD47 on T cells and its cognate receptor SIRP-α on DC define a novel regulatory pathway that may be involved in the maintenance of homeostasis by preventing the escalation of the inflammatory immune response.
Antigen-Specific Blockade of T Cells In Vivo Using Dimeric MHC Peptide
Authors: O’Herrin Sean M. , Slansky Jill E. , Tang Q. , Markiewicz Mary A. , Gajewski Thomas F. , Pardoll Drew M. , Schneck Jonathan P. , Bluestone Jeffrey A. 
Published: April 2014

Abstract
Ag-specific immune tolerance in clinical organ transplantation is currently an unrealized but critical goal of transplant biology. The specificity and avidity of multimerized MHC-peptide complexes suggests their potential ability to modulate T cell sensitization and effector functions. In this study, we examined the ability of MHC-peptide dimers to modulate T cell function both in vitro and in vivo. Soluble MHC dimers induced modulation of surface TCR expression and inhibited T cell cytolytic activity at nanomolar concentrations in vitro. Furthermore, engagement of TCR by soluble dimers resulted in phosphorylation of the TCR ζ-chain and recruitment and phosphorylation of ζ-associated protein-70 to the signaling complex, the latter of which increased upon dimer cross-linking. Significantly, Ag-specific inhibition of an alloreactive TCR-transgenic T cell population in vivo resulted in consequent outgrowth of an allogeneic tumor. The prolonged Ag-specific suppression of expansion and/or effector function of cognate T cells in vivo suggests that soluble MHC dimers may be a means of inducing sustained Ag-specific T cell unresponsiveness in vivo.
MHC Class I Allele Dosage Alters CD8 Expression by Intestinal Intraepithelial Lymphocytes
Authors: Podd Bradley S. , Åberg Caroline , Kudla Kimberly L. , Keene Lataya , Tobias Erin , Camerini Victoria 
Published: April 2014

AbstractThe development of TCR αβ+, CD8αβ+ intestinal intraepithelial lymphocytes (IEL) is dependent on MHC class I molecules expressed in the thymus, while some CD8αα+ IEL may arise independently of MHC class I. We examined the influence of MHC I allele dosage on the development CD8+ T cells in RAG 2−/− mice expressing the H-2Db-restricted transgenic TCR specific for the male, Smcy-derived H-Y Ag (H-Y TCR). IEL in male mice heterozygous for the restricting (H-2Db) and nonrestricting (H-2Dd) MHC class I alleles (MHC F1) were composed of a mixture of CD8αβ+ and CD8αα+ T cells, while T cells in the spleen were mostly CD8αβ+. This was unlike IEL in male mice homozygous for H-2Db, which had predominantly CD8αα+ IEL and few mostly CD8− T cells in the spleen. Our results demonstrate that deletion of CD8αβ+ cells in H-Y TCR male mice is dependent on two copies of H-2Db, whereas the generation of CD8αα+ IEL requires only one copy. The existence of CD8αβ+ and CD8αα+ IEL in MHC F1 mice suggests that their generation is not mutually exclusive in cells with identical TCR. Furthermore, our data imply that the level of the restricting MHC class I allele determines a threshold for conventional CD8αβ+ T cell selection in the thymus of H-Y TCR-transgenic mice, whereas the development of CD8αα+ IEL is dependent on, but less sensitive to, this MHC class I allele.
Immune Rejection of a Large Sarcoma Following Cyclophosphamide and IL-12 Treatment Requires Both NK and NK T Cells and Is Associated with the Induction of a Novel NK T Cell Population
Authors: Karnbach Claudia , Daws Michael R. , Niemi Eréne C. , Nakamura Mary C. 
Published: April 2014

AbstractCombined immunotherapy with cyclophosphamide (Cy) and IL-12, but not IL-12 alone, stimulates eradication of a large established solid tumor (20 mm), MCA207, a methylcholanthrene-induced murine sarcoma. In these studies we demonstrate that NK1.1+ cells and CD1d-dependent NK T cells each play important yet distinct roles in regression of a large tumor in response to Cy and IL-12, and we define a novel NK T cell subset, selectively increased by this treatment. Mice depleted of NK1.1+ cells demonstrated more rapid initial tumor growth and prolonged tumor regression following treatment, but tumors were eventually eradicated. In contrast, initial tumor regression following therapy was unimpaired in CD1d−/− mice, which are deficient in most NK T cells, but tumors recurred. No tumor regression occurred following Cy and IL-12 therapy in CD1d−/− mice that were depleted of NK1.1+ cells. We found that Cy and IL-12 induced the selective increase in liver and spleen lymphocytes of a unique NK T subpopulation (DX5+NK1.1−CD3+). These cells were not induced by treatment in CD1d−/− mice. Our studies demonstrate a contribution of both NK and NK T cells to the Cy- and IL-12-stimulated anti-tumor response. We describe the selective induction of a distinct NK T cell subset by Cy and IL-12 therapy, not seen following IL-12 therapy alone, which we suggest may contribute to the successful anti-tumor response induced by this immunotherapeutic regimen.
Peptide Requirement for CTL Activation Reflects the Sensitivity to CD3 Engagement: Correlation with CD8αβ Versus CD8αα Expression
Authors: Cawthon Andrew G. , Lu Haiping , Alexander-Miller Martha A. 
Published: April 2014

AbstractIn our previous studies, CTL that were sensitive to low concentrations of peptide Ag were found to be far superior to those requiring high concentrations of Ag for reducing viral burden when adoptively transferred into SCID mice. Thus it is important that we understand the mechanisms that control the requirement for peptide Ag with the long-term goal of selectively expanding these exquisitely sensitive cells in vivo. Although TCR affinity is one parameter that can affect the CTL sensitivity for Ag, we investigated whether additional mechanisms may also be involved. In studies using a TCR transgenic mouse model, we successfully generated CTL with identical TCR affinity that possess distinctly different activation requirements. Using both peptide Ag and anti-CD3 Ab to activate the CTL lines of high vs low avidity, we found that the variations in activation threshold are the result of differences in the required number of engaged TCR. Additionally, we have observed that the ratio of CD8αβ to CD8αα is significantly greater in CTL lines that are more sensitive to TCR engagement, which may contribute to the lower activation threshold of these CTL following CD3 engagement. These studies identify a novel mechanism by which the activation requirements of Ag-specific CTL are determined by demonstrating a direct correlation between the sensitivity to TCR engagement, the expression of levels CD8αβ vs αα, and the amount of peptide Ag required to reach the threshold for activation.
Neonatal Immunity Develops in a Transgenic TCR Transfer Model and Reveals a Requirement for Elevated Cell Input to Achieve Organ-Specific Responses
Authors: Li Lequn , Legge Kevin L. , Min Booki , Bell J. Jeremiah , Gregg Randal , Caprio Jacque , Zaghouani Habib 
Published: April 2014

AbstractIn recent years, it has become clear that neonatal exposure to Ag induces rather than ablates T cell immunity. Moreover, rechallenge with the Ag at adult age can trigger secondary responses that are distinct in the lymph node vs the spleen. The question addressed in this report is whether organ-specific secondary responses occur as a result of the diversity of the T cell repertoire or could they arise with homogeneous TCR-transgenic T cells. To test this premise, we used the OVA-specific DO11.10 TCR-transgenic T cells and established a neonatal T cell transfer system suitable for these investigations. In this system, neonatal T cells transferred from 1-day-old DO11.10/SCID mice into newborn (1-day-old) BALB/c mice migrate to the host’s spleen and maintain stable frequency. The newborn BALB/c hosts were then given Ig-OVA, an Ig molecule carrying the OVA peptide, and challenged with the OVA peptide in CFA at the age of 7 wk; then their secondary responses were analyzed. The findings show that the lymph node T cells were deviated and produced IL-4 instead of IFN-γ and the splenic T cells, although unable to proliferate or produce IFN-γ, secreted a significant level of IL-2. Supply of exogenous IL-12 during Ag stimulation restores both proliferation and IFN-γ production by the splenic T cells. This restorable form of splenic unresponsiveness referred to as IFN-γ-dependent anergy required a transfer of a high number of neonatal DO11.10/SCID T cells to develop. Thus, the frequency of neonatal T cell precursors rather than repertoire diversity exerts control on the development of organ-specific neonatal immunity.
Inhibition of Activated/Memory (CD45RO+) T Cells by Oxidative Stress Associated with Block of NF-κB Activation
Authors: Malmberg Karl-Johan , Arulampalam Velmurugesan , Ichihara Fumiko , Petersson Max , Seki Kazutake , Andersson Tove , Lenkei Rodica , Masucci Giuseppe , Pettersson Sven , Kiessling Rolf 
Published: April 2014

AbstractImpaired immune responses in cancer patients have been associated with oxidative stress. Increased levels of reactive oxygen species released from activated, tumor-infiltrating macrophages or granulocytes may therefore constitute a hurdle for effective immunotherapy against cancer. In this study, we investigated functional consequences and molecular events in T cells exposed to low levels of oxidative stress. We observed that cytokine production of human PBMC, upon stimulation with an HLA-A*0201-restricted influenza peptide and nonspecific receptor cross-linking, was reduced after exposure to micromolar levels of H2O2. Functional impairment as measured by IFN-γ release occurred earlier and at lower doses of exogenously added H2O2 than required to induce apoptosis. This suggests that there is a dose window of oxidative stress leading to T cell unresponsiveness in the absence of apoptosis. The reduction of Th1 cytokines, induced by H2O2, was predominantly observed in memory/effector (CD45RO+) T cells and correlated with a block in NF-κB activation. IL-10 production was more profoundly influenced by low doses of H2O2 than IFN-γ, TNF-α, and IL-2. The influence of H2O2 on production of IL-10 was not significantly different between memory/activated and naive T cells. These observations suggest that Th1 and Th2 cytokines are differently regulated under conditions of oxidative stress. Taken together, these findings may explain why Ag-experienced, CD45RO+, T cells found in the tumor milieu are functionally suppressed.
Genomic DNA Released by Dying Cells Induces the Maturation of APCs
Authors: Ishii Ken J. , Suzuki Koichi , Coban Cevayir , Takeshita Fumihiko , Itoh Yasushi , Matoba Hana , Kohn Leonard D. , Klinman Dennis M. 
Published: April 2014

Abstract
Mature APCs play a key role in the induction of Ag-specific immunity. This work examines whether genomic DNA released by dying cells provides a stimulus for APC maturation. Double-stranded but not single-stranded genomic DNA triggered APC to up-regulate expression of MHC class I/II and various costimulatory molecules. Functionally, dsDNA enhanced APC function in vitro and improved primary cellular and humoral immune responses in vivo. These effects were dependent on the length and concentration of the dsDNA but were independent of nucleotide sequence. The maturation of APC induced by dsDNA may promote host survival by improving immune surveillance at sites of tissue injury/infection.
Regulation of IL-12 p40 Promoter Activity in Primary Human Monocytes: Roles of NF-κB, CCAAT/Enhancer-Binding Protein β, and PU.1 and Identification of a Novel Repressor Element (GA-12) That Responds to IL-4 and Prostaglandin E2
Authors: Becker Christoph , Wirtz Stefan , Ma Xiaojing , Blessing Manfred , Galle Peter R. , Neurath Markus F. 
Published: April 2014

AbstractAppropriate regulation of IL-12 expression is critical for cell-mediated immune responses. In the present study, we have analyzed the regulation of IL-12 p40 promoter activity in primary human monocytes in vivo. Accordingly, we analyzed the p40 promoter by in vivo footprinting in resting and activated primary human blood CD14+ monocytes. Interestingly, footprints at binding sites for trans-activating proteins such as C/EBP, NF-κB, and ETS were only found upon stimulation with LPS and IFN-γ. In contrast, a footprint over a purine-rich sequence at −155, termed GA-12 (GATA sequence in the IL-12 promoter), was observed in resting, but not activated, cells. Further characterization of this site revealed specific complex formation at a protected GATA core motif in unstimulated primary monocytes and RAW264.7 macrophages. Mutagenesis within the GA-12 sequence caused a significant up-regulation of inducible IL-12 p40 promoter activity in both transient and stable transfection systems, suggesting a repressor function of this site. Furthermore, binding activity of the GA-12 binding protein GAP-12 was increased by treatment with two potent inhibitors of IL-12 expression, IL-4 and PGE2. Finally, we observed that IL-4-mediated repression of IL-12 p40 promoter activity is critically dependent on an intact GA-12 sequence. In summary, our data underline the complex regulation of the human IL-12 p40 promoter and identify GA-12 as a potent, novel repressor element that mediates IL-4-dependent suppression of inducible promoter activity in monocytes. Regulation of GAP-12 binding may thus modulate IL-12 p40 gene expression.