bluuebunny/crossref_metadata_2025_split huggingface dataset:
CTLA-4 Engagement Acts as a Brake on CD4+ T Cell Proliferation and Cytokine Production but Is Not Required for Tuning T Cell Reactivity in Adaptive Tolerance
Authors: Inobe Manabu , Schwartz Ronald H. 
Published: April 2014

AbstractAdaptive tolerance is the physiologic down-regulation of T cell responsiveness in the face of persistent antigenic stimulation. In this study, we examined the role of CTLA-4 in this process using CTLA-4-deficient and wild-type TCR transgenic, Rag2−/−, CD4+ T cells transferred into a T cell-deficient, Ag-expressing host. Surprisingly, we found that the tuning process of adoptively transferred T cells could be induced and the hyporesponsive state maintained in the absence of CTLA-4. Furthermore, movement to a deeper state of anergy following restimulation in vivo in a second Ag-bearing host was also unaffected. In contrast, CTLA-4 profoundly inhibited late T cell expansion in vivo following both primary and secondary transfers, and curtailed IL-2 and IFN-γ production. Removal of this braking function in CTLA-4-deficient mice following Ag stimulation may explain their lymphoproliferative dysregulation.
Regulatory T Cell Suppression and Anergy Are Differentially Regulated by Proinflammatory Cytokines Produced by TLR-Activated Dendritic Cells
Authors: Kubo Takekazu , Hatton Robin D. , Oliver James , Liu Xiaofen , Elson Charles O. , Weaver Casey T. 
Published: April 2014

Abstract
CD25+CD4+ regulatory T cells (Tregs) are required for the maintenance of peripheral tolerance to certain self Ags. In this study, the requirements for murine Treg-suppressive activity and proliferation were examined in the context of the maturation of myeloid dendritic cells (DCs). We find that the suppressive function of Tregs is critically dependent on immature DCs and is readily reversed by the maturation of DCs induced by GM-CSF, but does not require TLR activation of either DCs or Tregs. In contrast, reversal of Treg anergy is dependent on TLR activation of DCs, and involves the potentiation of Treg responsiveness to IL-2 by cooperative effects of IL-6 and IL-1, both of which are produced by TLR-activated, mature DCs. Thus, proinflammatory cytokines produced by TLR-activated, mature DCs are required for reversal of Treg anergy, but are not required to overcome Treg suppression.
CD25− T Cells Generate CD25+Foxp3+ Regulatory T Cells by Peripheral Expansion
Authors: Curotto de Lafaille Maria A. , Lino Andreia C. , Kutchukhidze Nino , Lafaille Juan J. 
Published: April 2014

Abstract
Naturally occurring CD4+ regulatory T cells are generally identified through their expression of CD25. However, in several experimental systems considerable Treg activity has been observed in the CD4+CD25− fraction. Upon adoptive transfer, the expression of CD25 in donor-derived cells is not stable, with CD4+CD25+ cells appearing in CD4+CD25− T cell-injected animals and vice versa. We show in this study that CD25+ cells arising from donor CD25− cells upon homeostatic proliferation in recipient mice express markers of freshly isolated Treg cells, display an anergic state, and suppress the proliferation of other cells in vitro. The maintenance of CD25 expression by CD4+CD25+ cells depends on IL-2 secreted by cotransferred CD4+CD25− or by Ag-stimulated T cells in peripheral lymphoid organs.
Endogenous IFN-α Production by Plasmacytoid Dendritic Cells Exerts an Antiviral Effect on Thymic HIV-1 Infection
Authors: Gurney Kevin B. , Colantonio Arnaud D. , Blom Bianca , Spits Hergen , Uittenbogaart Christel H. 
Published: April 2014

Abstract
Plasmacytoid dendritic cells (pDC) are the principal producers of IFN-α in response to viral infection. Because pDC are present in the thymus, we investigated the consequences of HIV-1-induced IFN-α production by thymic pDC. We observed that thymic pDC as well as thymocytes express intracellular IFN-α upon infection with HIV-1. However, only the pDC could suppress HIV-1 replication, because depletion of pDC resulted in enhancement of HIV-1 replication in thymocytes. Thymic pDC could also produce IFN-α in response to CpG oligonucleotides, consistent with the observations of others that peripheral pDC produce IFN-α upon engagement of TLR-9. Importantly, CpG considerably increased IFN-α production induced by HIV-1, and addition of CpG during HIV-1 infection enhanced expression of the IFN response protein MxA in thymocytes and strongly reduced HIV-replication. Our data indicate that thymic pDC modulate HIV-1 replication through secretion of IFN-α. The degree of inhibition depends on the level of IFN-α produced by the thymic pDC.
Papillon-Lefèvre Syndrome: Correlating the Molecular, Cellular, and Clinical Consequences of Cathepsin C/Dipeptidyl Peptidase I Deficiency in Humans
Authors: Pham Christine T. N. , Ivanovich Jennifer L. , Raptis Sofia Z. , Zehnbauer Barbara , Ley Timothy J. 
Published: April 2014

Abstract
A variety of neutral serine proteases are important for the effector functions of immune cells. The neutrophil-derived serine proteases cathepsin G and neutrophil elastase are implicated in the host defense against invading bacterial and fungal pathogens. Likewise, the cytotoxic lymphocyte and NK cell granule-associated granzymes A and B are important for the elimination of virus-infected cells. The activation of many of these serine proteases depends on the N-terminal processing activity of the lysosomal cysteine protease cathepsin C/dipeptidyl peptidase I (DPPI). Although mice deficient in DPPI have defects in serine protease activation in multiple cellular compartments, the role of DPPI for human serine protease activation is largely undefined. Papillon-Lefèvre syndrome (PLS) is a rare autosomal recessive disease associated with loss-of-function mutations in the DPPI gene locus. In this study, we established that the loss of DPPI activity is associated with severe reduction in the activity and stability of neutrophil-derived serine proteases. Surprisingly, patients with PLS retain significant granzyme activities in a cytotoxic lymphocyte compartment (lymphokine-activated killer) and have normal lymphokine-activated killer-mediated cytotoxicity against K562 cells. Neutrophils from patients with PLS do not uniformly have a defect in their ability to kill Staphylococcus aureus and Escherichia coli, suggesting that serine proteases do not represent the major mechanism used by human neutrophils for killing common bacteria. Therefore, this study defines the consequences of DPPI deficiency for the activation of several immune cell serine proteases in humans, and provides a molecular explanation for the lack of a generalized T cell immunodeficiency phenotype in patients with PLS.
Chemoattractant Signals and β2 Integrin Occupancy at Apical Endothelial Contacts Combine with Shear Stress Signals to Promote Transendothelial Neutrophil Migration
Authors: Cinamon Guy , Shinder Vera , Shamri Revital , Alon Ronen 
Published: April 2014

Abstract
Lymphocyte transendothelial migration (TEM) is promoted by fluid shear signals and apical endothelial chemokines. Studying the role of these signals in neutrophil migration across differently activated HUVEC in a flow chamber apparatus, we gained new insights into how neutrophils integrate multiple endothelial signals to promote TEM. Neutrophils crossed highly activated HUVEC in a β2 integrin-dependent manner but independently of shear. In contrast, neutrophil migration across resting or moderately activated endothelium with low-level β2 integrin ligand activity was dramatically augmented by endothelial-presented chemoattractants, conditional to application of physiological shear stresses and intact β2 integrins. Shear stress signals were found to stimulate extensive neutrophil invaginations into the apical endothelial interface both before and during TEM. A subset of invaginating neutrophils completed transcellular diapedesis through individual endothelial cells within &lt;1 min. Our results suggest that low-level occupancy of β2 integrins by adherent neutrophils can mediate TEM only if properly coupled to stimulatory shear stress and chemoattractant signals transduced at the apical neutrophil-endothelial interface.
Anatomical Heterogeneity of Memory CD4+ T Cells Due to Reversible Adaptation to the Microenvironment
Authors: Kassiotis George , Stockinger Brigitta 
Published: April 2014

Abstract
The memory T cell pool is characterized by a substantial degree of heterogeneity in phenotype and function as well as anatomical distribution, but the underlying mechanisms remain unclear. In this study we confirm that the memory CD4+ T cell pool in wild-type and TCR-transgenic mice consists of heterogeneous subsets, as defined by surface marker expression or cytokine production. Extralymphoid sites contain significant numbers of memory CD4+ T cells, which are phenotypically and functionally distinct from their lymphoid counterparts. However, we show in this study that the phenotype of lymphoid and extralymphoid memory T cells is not stable. Instead, the unique properties of extralymphoid memory T cells are acquired upon migration into extralymphoid sites and are lost when memory T cells migrate back into lymphoid organs. Thus, at least some of the extralymphoid properties may represent a transient activation state that can be adopted by T cells belonging to a single memory T cell pool. Furthermore, such intermittent activation during or after migration into extralymphoid sites could provide an important signal, promoting the survival and functional competence of memory T cells in the absence of Ag.
Differential Activation of ERK, p38, and JNK Required for Th1 and Th2 Deviation in Myelin-Reactive T Cells Induced by Altered Peptide Ligand
Authors: Singh Rana A. K. , Zhang Jingwu Z. 
Published: April 2014

Abstract
Autoreactive T cells can be induced by altered peptide ligands to switch Th1 and Th2 phenotypes. The underlying molecular mechanism is critical for understanding of activation of autoreactive T cells and development of novel therapeutic strategies for autoimmune conditions. In this study, we demonstrated that analog peptides of an immunodominant epitope of myelin basic protein (residues 83–99) with alanine substitution at Val86 and His88 had a unique partial agonistic property in the induction of Th1 or Th2 deviation in MBP83–99-reactive T cell clones typical of Th0 phenotype. The observed phenotypic switch involved differential activation of ERK, p38, and JNK MAPKs. More specifically, Th1 deviation induced by peptide 86V→A (86A) correlated with enhanced p38 and JNK activities, while Th2 deviation by peptide 88H→A (88A) was associated with up-regulated ERK activity and a basal level of p38 and JNK activity. Further characterization revealed that a specific inhibitor for ERK selectively prevented Th2 deviation of MBP83–99-specific T cells. Conversely, specific inhibitors for p38 and JNK blocked Th1 deviation in the same T cell preparations induced by peptide 86A. The findings have important implications in our understanding of regulation of ERK, p38, and JNK by altered peptide ligands and their role in cytokine regulation and phenotype switch of autoreactive T cells.
A Sudden Decline in Active Membrane-Bound TGF-β Impairs Both T Regulatory Cell Function and Protection against Autoimmune Diabetes
Authors: Gregg Randal K. , Jain Renu , Schoenleber Scott J. , Divekar Rohit , Bell J. Jeremiah , Lee Hyun-Hee , Yu Ping , Zaghouani Habib 
Published: April 2014

Abstract
Autoimmunity presumably manifests as a consequence of a shortfall in the maintenance of peripheral tolerance by CD4+CD25+ T regulatory cells (Tregs). However, the mechanism underlying the functional impairment of Tregs remains largely undefined. In this study a glutamic acid decarboxylase (GAD) diabetogenic epitope was expressed on an Ig to enhance tolerogenic function, and the resulting Ig-GAD expanded Tregs in both young and older insulitis-positive, nonobese diabetic (NOD) mice, but delayed autoimmune diabetes only in the former. Interestingly, Tregs induced at 4 wk of age had significant active membrane-bound TGF-β (mTGF-β) and sustained protection against diabetes, whereas Tregs expanded during insulitis had minimal mTGF-β and could not protect against diabetes. The Tregs probably operate suppressive function through mTGF-β, because Ab blockade of mTGF-β nullifies protection against diabetes. Surprisingly, young Tregs that modulated pathogenic T cells maintained stable frequency over time in the protected animals, but decreased their mTGF-β at the age of 8 wk. More strikingly, these 8-wk-old mTGF-β-negative Tregs, which were previously protective, became unable to confer resistance against diabetes. Thus, a developmental decline in active mTGF-β nullifies Treg function, leading to a break in tolerance and the onset of diabetes.
Plasmablast and Plasma Cell Production and Distribution in Trout Immune Tissues
Authors: Bromage Erin S. , Kaattari Ilsa M. , Zwollo Patty , Kaattari Stephen L. 
Published: April 2014

AbstractThese studies describe the in vitro and ex vivo generation of plasmablasts and plasma cells in trout (Oncorhynchus mykiss) peripheral blood and splenic and anterior kidney tissues. Cells were derived either from naive trout and cultured with the polyclonal activator, Escherichia coli LPS, or from trout that had been immunized with trinitrophenyl-keyhole limpet hemocyanin. Hydroxyurea was used to resolve populations of replicating (plasmablast) and nonreplicating (plasma cell) Ab-secreting cells (ASC). Complete inhibition of Ig secretion was only observed within the PBL. Both anterior kidney and splenic lymphocytes possessed a subset of ASCs that were hydroxyurea resistant. Thus, in vitro production of plasma cells appears to be restricted to the latter two tissues, whereas peripheral blood is exclusively restricted to the production of plasmablasts. After immunization with trinitrophenyl-keyhole limpet hemocyanin, specific ASC could be isolated from all immune organs; however, the anterior kidney contained 98% of all ASC. Late in the response (&gt;10 wk), anterior kidney ASC secreted specific Ab for at least 15 days in culture, indicating that they were long-lived plasma cells. Cells from spleen and peripheral blood lost all capacity to secrete specific Ab in the absence of Ag. Late in the Ab response, high serum titer levels are solely the result of Ig secretion from anterior kidney plasma cells.
Expansion of Myeloid Suppressor Cells in SHIP-Deficient Mice Represses Allogeneic T Cell Responses
Authors: Ghansah Tomar , Paraiso Kim H. T. , Highfill Steven , Desponts Caroline , May Sarah , McIntosh Joseph K. , Wang Jia-Wang , Ninos John , Brayer Jason , Cheng Fengdong , Sotomayor Eduardo , Kerr William G. 
Published: April 2014

AbstractPreviously we demonstrated that SHIP−/− mice accept allogeneic bone marrow transplants (BMT) without significant acute graft-vs-host disease (GvHD). In this study we show that SHIP−/− splenocytes and lymph node cells are poor stimulators of allogeneic T cell responses that cause GvHD. Intriguingly, SHIP−/− splenocytes prime naive T cell responses to peptide epitopes, but, conversely, are partially impaired for priming T cell responses to whole Ag. However, dendritic cells (DC) purified from SHIP−/− splenocytes prime T cell responses to allogeneic targets, peptide epitopes, and whole Ag as effectively as SHIP+/+ DC. These findings point to an extrinsic effect on SHIP−/− DC that impairs priming of allogeneic T cell responses. Consistent with this extrinsic effect, we found that a dramatic expansion of myeloid suppressor cells in SHIP−/− mice impairs priming of allogeneic T cells. These findings suggest that SHIP expression or its activity could be targeted to selectively compromise T cell responses that mediate GvHD and graft rejection.
Early Growth Response Gene-2, a Zinc-Finger Transcription Factor, Is Required for Full Induction of Clonal Anergy in CD4+ T Cells
Authors: Harris John E. , Bishop Kenneth D. , Phillips Nancy E. , Mordes John P. , Greiner Dale L. , Rossini Aldo A. , Czech Michael P. 
Published: April 2014

Abstract
Ag-specific immune tolerance results from the induction of cellular mechanisms that limit T cell responses to selective Ags. One of these mechanisms is characterized by attenuated proliferation and decreased IL-2 production in fully stimulated CD4+ Th cells and is denoted T cell anergy. We report the identification of the early growth response gene (Egr-2; Krox-20), a zinc-finger transcription factor, as a key protein required for induction of anergy in cultured T cells. Gene array screening revealed high Egr-2 expression distinctly persists in anergized but not proliferating murine A.E7 T cells. In contrast, Egr-1, a related family member induced upon costimulation, displays little or no expression in the anergic state. IL-2-mediated abrogation of anergy causes rapid depletion of Egr-2 protein. Full stimulation of anergic A.E7 T cells fails to enhance IL-2 and Egr-1 expression, whereas Egr-2 expression is greatly increased. Silencing Egr-2 gene expression by small interfering RNA treatment of cultured A.E7 T cells before incubation with anti-CD3 alone prevents full induction of anergy. However, small interfering RNA-mediated depletion of Egr-2 5 days after anergy induction does not appear to abrogate hyporesponsiveness to stimulation. These data indicate that sustained Egr-2 expression is necessary to induce a full anergic state through the actions of genes regulated by this transcription factor.
Peptidoglycan Molecular Requirements Allowing Detection by the Drosophila Immune Deficiency Pathway
Authors: Stenbak Carolyn R. , Ryu Ji-Hwan , Leulier François , Pili-Floury Sebastien , Parquet Claudine , Hervé Mireille , Chaput Catherine , Boneca Ivo G. , Lee Won-Jae , Lemaitre Bruno , Mengin-Lecreulx Dominique 
Published: April 2014

Abstract
Innate immune recognition of microbes is a complex process that can be influenced by both the host and the microbe. Drosophila uses two distinct immune signaling pathways, the Toll and immune deficiency (Imd) pathways, to respond to different classes of microbes. The Toll pathway is predominantly activated by Gram-positive bacteria and fungi, while the Imd pathway is primarily activated by Gram-negative bacteria. Recent work has suggested that this differential activation is achieved through peptidoglycan recognition protein (PGRP)-mediated recognition of specific forms of peptidoglycan (PG). In this study, we have further analyzed the specific PG molecular requirements for Imd activation through the pattern recognition receptor PGRP-LC in both cultured cell line and in flies. We found that two signatures of Gram-negative PG, the presence of diaminopimelic acid in the peptide bridge and a 1,6-anhydro form of N-acetylmuramic acid in the glycan chain, allow discrimination between Gram-negative and Gram-positive bacteria. Our results also point to a role for PG oligomerization in Imd activation, and we demonstrate that elements of both the sugar backbone and the peptide bridge of PG are required for optimum recognition. Altogether, these results indicate multiple requirements for efficient PG-mediated activation of the Imd pathway and demonstrate that PG is a complex immune elicitor.
Site-Specific Inhibitors of NADPH Oxidase Activity and Structural Probes of Flavocytochrome b: Characterization of Six Monoclonal Antibodies to the p22phox Subunit
Authors: Taylor Ross M. , Burritt James B. , Baniulis Danas , Foubert Thomas R. , Lord Connie I. , Dinauer Mary C. , Parkos Charles A. , Jesaitis Algirdas J. 
Published: April 2014

Abstract
The integral membrane protein flavocytochrome b (Cyt b) is the catalytic core of the human phagocyte NADPH oxidase, an enzyme complex that initiates a cascade of reactive oxygen species important in the elimination of infectious agents. This study reports the generation and characterization of six mAbs (NS1, NS2, NS5, CS6, CS8, and CS9) that recognize the p22phox subunit of the Cyt b heterodimer. Each of the mAbs specifically detected p22phox by Western blot analysis but did not react with intact neutrophils in FACS studies. Phage display mapping identified core epitope regions recognized by mAbs NS2, NS5, CS6, CS8, and CS9. Fluorescence resonance energy transfer experiments indicated that mAbs CS6 and CS8 efficiently compete with Cascade Blue-labeled mAb 44.1 (a previously characterized, p22phox-specific mAb) for binding to Cyt b, supporting phage display results suggesting that all three Abs recognize a common region of p22phox. Energy transfer experiments also suggested the spatial proximity of the mAb CS9 and mAb NS1 binding sites to the mAb 44.1 epitope, while indicating a more distant proximity between the mAb NS5 and mAb 44.1 epitopes. Cell-free oxidase assays demonstrated the ability of mAb CS9 to markedly inhibit superoxide production in a concentration-dependent manner, with more moderate levels of inhibition observed for mAbs NS1, NS5, CS6, and CS8. A combination of computational predictions, available experimental data, and results obtained with the mAbs reported in this study was used to generate a novel topology model of p22phox.
Plasticity within the Antigen-Combining Site May Manifest as Molecular Mimicry in the Humoral Immune Response
Authors: Goel Manisha , Krishnan Lavanya , Kaur Surinder , Kaur Kanwal J. , Salunke Dinakar M. 
Published: April 2014

Abstract
Structural and physiological facets of carbohydrate-peptide mimicry were addressed by analyzing the Ab response to α-d-mannopyranoside. mAbs against α-d-mannopyranoside were generated and screened with the carbohydrate-mimicking 12 mer (DVFYPYPYASGS) peptide. Three mAbs, 2D10, 1H11, and 1H7, which were subjected to detailed analysis, exhibit diverse V gene usage, indicating their independent germline origins. Although the mAb 1H7 was specific in binding only to the immunizing Ag, the Abs 2D10 and 1H11 recognize the 12 mer peptide as well as the immunogen, α-d-mannopyranoside. The Abs that recognize mimicry appear to bind to a common epitope on the peptide and do not share the mode of peptide binding with Con A. Binding kinetics and thermodynamics of Ag recognition suggest that the Ab that does not recognize peptide-carbohydrate mimicry probably has a predesigned mannopyranoside-complementing site. In contrast, the mimicry-recognizing Abs adopt the Ag-combining site only on exposure to the sugar, exploiting the conformational flexibility in the CDRs. Although the mAb 1H7 showed unique specificity toward mannopyranoside, the mimicry-recognizing Abs 2D10 and 1H11 exhibited degenerate specificities with regard to other sugar moieties. It is proposed that the degeneracy of specificity arising from the plasticity at the Ag-combining site in a subset of the Ab clones may be responsible for exhibiting molecular mimicry in the context of Ab response.