bluuebunny/crossref_metadata_2025_split huggingface dataset:
Accelerated Notch-Dependent Degradation of E47 Proteins in Aged B Cell Precursors Is Associated with Increased ERK MAPK Activation
Authors: King Anne M. , Van der Put Elaine , Blomberg Bonnie B. , Riley Richard L. 
Published: April 2014

Abstract
The transcriptional regulator E47, encoded by the E2A gene, is crucial to B lymphopoiesis. In BALB/c senescent mice (∼2 years old), the incidence of E47-expressing pro-B cells in vivo and E47 protein steady state levels in B cell precursors in vitro were reduced. Poor expression of E47 protein was a consequence of accelerated proteasome-mediated turnover and was associated with heightened ubiquitin modification of E2A-encoded proteins in aged B cell precursors. Both MAPK and Notch activity have been previously associated with E2A-encoded protein stability in lymphocytes. Aged B cell precursors exhibited heightened levels of MAPK activity reflected in increased levels of phospho-ERK proteins. Phosphorylation of E2A-encoded proteins was also increased in aged B cell precursors and pharmacologic inhibition of MEK-1 resulted in a partial restoration of their E47 protein. Both Notch proteins and their Delta-like ligands were detected comparably in young and aged B cell precursors. Either inhibition of Notch activation via gamma-secretase or Ab blockade of Notch-Delta-like ligand interactions partially restored E47 expression in aged B cell precursors. We hypothesize that increased MAPK activity promotes phosphorylation of E2A-encoded protein in aged B cell precursors. Subsequently, E2A-encoded proteins undergo ubiquitination and accelerated degradation in a Notch-dependent process. The dysregulation of E2A-encoded protein expression may contribute to the reductions seen in early B lymphopoiesis during murine senescence.
Discrete T Cell Populations with Specificity for a Neo-Self-Antigen Bear Distinct Imprints of Tolerance
Authors: Standifer Nathan E. , Stacy Sue , Kraig Ellen , Infante Anthony J. 
Published: April 2014

Abstract
Mice expressing the Torpedo acetylcholine receptor α-chain as a neo-self-Ag exhibit a reduced frequency of T cells responding to the immunodominant epitope Tα146–162 indicating a degree of tolerance. We characterized tolerance induction in these animals by analyzing the residual Tα146–162-responsive T cell population and comparing it to that of nontransgenic littermates. Using CD4high sorting, we isolated the vast majority of Ag-reactive T cells from both strains of mice. Quantitative studies of the CD4high populations in transgenic mice following immunization with Tα146–162 revealed a diminished expansion of cells expressing the canonical TCRBV6 but not other TCRBV gene segments when compared with nontransgenic littermates. In addition, CD4high cells from transgenic mice were functionally hyporesponsive to Tα146–162 in terms of proliferation and cytokine secretion regardless of TCRBV gene segment use. TCR sequence analysis of transgenic Vβ6+CD4high cells revealed a reduced frequency of cells expressing a conserved motif within the TCRβ CDR3. Thus, the canonical Tα146–162 responsive, Vβ6+ population demonstrates both quantitative and qualitative deficits that correlate with an altered TCR repertoire whereas the non-Vβ6 population in transgenic mice exhibits only a reduction in peptide responsiveness, a qualitative defect. These data demonstrate that discrete autoreactive T cell populations with identical peptide/MHC specificity in Torpedo acetylcholine receptor-α-transgenic animals bear distinct tolerance imprints.
IL-12 Controls Cytotoxicity of a Novel Subset of Self-Antigen-Specific Human CD28+ Cytolytic T Cells
Authors: Barbey Catherine , Baumgaertner Petra , Devevre Estelle , Rubio-Godoy Verena , Derre Laurent , Bricard Gabriel , Guillaume Philippe , Luescher Immanuel F. , Liénard Danielle , Cerottini Jean-Charles , Romero Pedro , Rufer Nathalie , Speiser Daniel E. 
Published: April 2014

Abstract
Activated CD8 T cells develop cytotoxicity against autologous cells bearing foreign Ags and self/tumor Ags. However, self-specific cytolysis needs to be kept under control to avoid overwhelming immunopathology. After peptide vaccination of melanoma patients, we studied molecular and functional properties of T cell subsets specific for the self/tumor Ag Melan-A/MART-1. Ex vivo analysis revealed three Ag-specific effector memory (EM) populations, as follows: CD28-negative EM (EM28−) T cells strongly expressing granzyme/perforin, and two EM28+ subsets, one with high and the other with low level expression of these cytotoxic proteins. For further functional characterization, we generated 117 stable CD8 T cell clones by ex vivo flow cytometry-based sorting of these subsets. All EM28−-derived clones lysed target cells with high efficacy. In contrast, EM28+-derived clones were heterogenous, and could be classified in two groups, one with high and the other with low killing capacity, correlating with granzyme/perforin expression. High and low killer phenotypes remained surprisingly stable for several months. However, strongly increased granzyme expression and cytotoxicity were observed after exposure to IL-12. Thus, the data reveal a newly identified subset of CD28+ conditional killer T cells. Because CD28 can mediate strong costimulatory signals, tight cytotoxicity control, as shown in this study through IL-12, may be particularly important for subsets of T cells expressing CD28.
T-Independent Activation-Induced Cytidine Deaminase Expression, Class-Switch Recombination, and Antibody Production by Immature/Transitional 1 B Cells
Authors: Ueda Yoshihiro , Liao Dongmei , Yang Kaiyong , Patel Anjali , Kelsoe Garnett 
Published: April 2014

Abstract
Inflammation elicits a splenic lymphopoiesis of unknown physiologic significance but one that juxtaposes developing B cells and exogenous Ag. We show that immature and transitional 1 (immature/T1) B cells constitutively express activation-induced cytidine deaminase and B lymphocyte-induced maturation protein 1 in amounts that support accelerated plasmacytic differentiation and limited class-switch recombination. In vivo, activation of immature/T1 B cells by TLR ligands or bacterial vaccine rapidly induces T1 cells to divide, proliferate, and secrete IgM, IgG, or IgA Ab; in vitro, proliferation and differentiation are substantially enhanced by B cell-activating factor. We propose that inflammation-induced extramedullary lymphopoiesis represents a specialized mechanism for innate Ab responses to microbial pathogens.
IFN Regulatory Factor-2 Regulates Macrophage Apoptosis through a STAT1/3- and Caspase-1-Dependent Mechanism
Authors: Cuesta Natalia , Nhu Quan M. , Zudaire Enrique , Polumuri Swamy , Cuttitta Frank , Vogel Stefanie N. 
Published: April 2014

Abstract
IFN regulatory factor (IRF)-2−/− mice are significantly more resistant to LPS challenge than wild-type littermates, and this was correlated with increased numbers of apoptotic Kupffer cells. To assess the generality of this observation, and to understand the role of IRF-2 in apoptosis, responses of peritoneal macrophages from IRF-2+/+ and IRF-2−/− mice to apoptotic stimuli, including the fungal metabolite, gliotoxin, were compared. IRF-2−/− macrophages exhibited a consistently higher incidence of apoptosis that failed to correlate with caspase-3/7 activity. Using microarray gene expression profiling of liver RNA samples derived from IRF-2+/+ and IRF-2−/− mice treated with saline or LPS, we identified &gt;40 genes that were significantly down-regulated in IRF-2−/− mice, including Stat3, which has been reported to regulate apoptosis. Compared with IRF-2+/+ macrophages, STAT3α mRNA was up-regulated constitutively or after gliotoxin treatment of IRF-2−/− macrophages, whereas STAT3β mRNA was down-regulated. Phospho-Y705-STAT3, phospho-S727-STAT1, and phospho-p38 protein levels were also significantly higher in IRF-2−/− than control macrophages. Activation of the STAT signaling pathway has been shown to elicit expression of CASP1 and apoptosis. IRF-2−/− macrophages exhibited increased basal and gliotoxin-induced caspase-1 mRNA expression and enhanced caspase-1 activity. Pharmacologic inhibition of STAT3 and caspase-1 abolished gliotoxin-induced apoptosis in IRF-2−/− macrophages. A novel IFN-stimulated response element, identified within the murine promoter of Casp1, was determined to be functional by EMSA and supershift analysis. Collectively, these data support the hypothesis that IRF-2 acts as a transcriptional repressor of Casp1, and that the absence of IRF-2 renders macrophages more sensitive to apoptotic stimuli in a caspase-1-dependent process.
Stimulation of an Unfolded Protein Response Impairs MHC Class I Expression
Authors: de Almeida Sérgio F. , Fleming John V. , Azevedo Jorge E. , Carmo-Fonseca Maria , de Sousa Maria 
Published: April 2014

Abstract
HFE C282Y is an example of a mutant protein that does not fold correctly, is retained in the endoplasmic reticulum, and was found previously to diminish surface expression of MHC class I (MHC-I). We now show that its expression in 293T cells triggers an unfolded protein response (UPR), as revealed by the increased levels of H chain binding protein, GRP94, and C/EBP homologous protein. Elevated levels of these proteins were also found in HFE C282Y homozygous PBMCs. Following the UPR induction, a decrease in MHC-I cell surface expression was observed. This defect in MHC-I could be mimicked, however, by overexpression of transcriptionally active isoforms of activating transcription factor-6 and X box-binding protein-1, which induced the UPR, and reversed in HFE C282Y-expressing cells by using dominant-negative constructs that block UPR signaling. The present results provide evidence to the finding that stimulation of an UPR affects MHC-I expression.
CD1-Restricted Recognition of Exogenous and Self-Lipid Antigens by Duodenal γδ+ T Lymphocytes
Authors: Russano Anna M. , Bassotti Gabrio , Agea Elisabetta , Bistoni Onelia , Mazzocchi Alessandro , Morelli Antonio , Porcelli Steven A. , Spinozzi Fabrizio 
Published: April 2014

Abstract
γδ T cells are present in the mucosal intestinal epithelia and secrete factors necessary to maintain tissue integrity. Ags recognized by these cells are poorly defined, although in mice non-classical MHC class I molecules have been implicated. Since MHC class I-like CD1 receptors are widely expressed at the surface of epithelial and dendritic intestinal cells and have the capacity to present lipid Ags to T cells, we hypothesized that these molecules might present autologous and/or exogenous phospholipids to intestinal γδ T lymphocytes. Intraepithelial T lymphocytes from normal human duodenal mucosal biopsies were cloned and exposed to natural and synthetic phospholipids using CD1a-, CD1b-, CD1c- or CD1d-transfected C1R lymphoblastoid or HeLa cell lines as APCs. Their cytolytic properties and regulatory cytokine secretion were also examined. Most clones obtained from duodenal mucosa (up to 70%) were TCRαβ+, and either CD4+ or CD8+, whereas 20% were CD4−CD8− (6 clones) or TCRγδ+ (12 clones). A relevant percentage (up to 66%) of TCRγδ+ but few (&lt;5%) TCRαβ+ T cell clones responded to synthetic and/or natural phospholipids presented by CD1 molecules, as measured by both [3H]thymidine incorporation and IL-4 release assays. A Th1-like cytolytic and functional activity along with the ability to secrete regulatory cytokines was observed in most phospholipid-specific γδ T cell clones. Thus, a substantial percentage of TCRγδ+ but few TCRαβ+ from human duodenal mucosa recognize exogenous phospholipids in a CD1-restricted fashion. This adaptive response could contribute to mucosal homeostasis, but could also favor the emergence of inflammatory or allergic intestinal diseases.
Superantigen Presentation by Airway Smooth Muscle to CD4+ T Lymphocytes Elicits Reciprocal Proasthmatic Changes in Airway Function
Authors: Veler Haviva , Hu Aihua , Fatma Sumbul , Grunstein Judith S. , DeStephan Christine M. , Campbell Donald , Orange Jordan S. , Grunstein Michael M. 
Published: April 2014

Abstract
Microbial products serving as superantigens (SAgs) have been implicated in triggering various T cell-mediated chronic inflammatory disorders, including severe asthma. Given earlier evidence demonstrating that airway smooth muscle (ASM) cells express MHC class II molecules, we investigated whether ASM can present SAg to resting CD4+ T cells, and further examined whether this action reciprocally elicits proasthmatic changes in ASM responsiveness. Coincubation of CD4+ T cells with human ASM cells pulsed with the SAg, staphylococcal enterotoxin A (SEA), elicited adherence and clustering of class II and CD3 molecules at the ASM/T cell interface, indicative of immunological synapse formation, in association with T cell activation. This ASM/T cell interaction evoked up-regulated mRNA expression and pronounced release of the Th2-type cytokine, IL-13, into the coculture medium, which was MHC class II dependent. Moreover, when administering the conditioned medium from the SEA-stimulated ASM/T cell cocultures to isolated naive rabbit ASM tissues, the latter exhibited proasthmatic-like changes in their constrictor and relaxation responsiveness that were prevented by pretreating the tissues with an anti-IL-13 neutralizing Ab. Collectively, these observations are the first to demonstrate that ASM can present SAg to CD4+ T cells, and that this MHC class II-mediated cooperative ASM/T cell interaction elicits release of IL-13 that, in turn, evokes proasthmatic changes in ASM constrictor and relaxant responsiveness. Thus, a new immuno-regulatory role for ASM is identified that potentially contributes to the pathogenesis of nonallergic (intrinsic) asthma and, accordingly, may underlie the reported association between microbial SAg exposure, T cell activation, and severe asthma.
Capture of Target Cell Membrane Components via Trogocytosis Is Triggered by a Selected Set of Surface Molecules on T or B Cells
Authors: Hudrisier Denis , Aucher Anne , Puaux Anne-Laure , Bordier Christine , Joly Etienne 
Published: April 2014

Abstract
Key events of T and B cell biology are regulated through direct interaction with APC or target cells. Trogocytosis is a process whereby CD4+ T, CD8+ T, and B cells capture their specific membrane-bound Ag through the acquisition of plasma membrane fragments from their cellular targets. With the aim of investigating whether the ability to trigger trogocytosis was a selective property of Ag receptors, we set up an assay that allowed us to test the ability of many different cell surface molecules to trigger trogocytosis. On the basis of the analysis of a series of surface molecules on CD4+ T, CD8+ T, and B cells, we conclude that a set of cell type-specific surface determinants, including but not limited to Ag receptors, do trigger trogocytosis. On T cells, these determinants include components of the TCR/CD3 as well as that of coreceptors and of several costimulatory molecules. On B cells, we identified only the BCR and MHC molecules as potentials triggers of trogocytosis. Remarkably, latrunculin, which prevents actin polymerization, impaired trogocytosis by T cells, but not by B cells. This was true even when the same Abs were used to trigger trogocytosis in T or B cells. Altogether, our results indicate that although trogocytosis is performed by all hemopoietic cells tested thus far, both the receptors and the mechanisms involved can differ depending on the lineage of the cell acquiring membrane materials from other cells. This could therefore account for the different biological consequences of Ag capture via trogocytosis proposed for different types of cells.
Genome-Wide Identification of Novel Genes Involved in Early Th1 and Th2 Cell Differentiation
Authors: Lund Riikka J. , Löytömäki Maritta , Naumanen Tiina , Dixon Craig , Chen Zhi , Ahlfors Helena , Tuomela Soile , Tahvanainen Johanna , Scheinin Joonas , Henttinen Tiina , Rasool Omid , Lahesmaa Riitta 
Published: April 2014

Abstract
Th cell subtypes, Th1 and Th2, are involved in the pathogenesis or progression of many immune-mediated diseases, such as type 1 diabetes and asthma, respectively. Defining the molecular networks and factors that direct Th1 and Th2 cell differentiation will help to understand the pathogenic mechanisms causing these diseases. Some of the key factors regulating this differentiation have been identified, however, they alone do not explain the process in detail. To identify novel factors directing the early differentiation, we have studied the transcriptomes of human Th1 and Th2 cells after 2, 6, and 48 h of polarization at the genome scale. Based on our current and previous studies, 288 genes or expressed sequence tags, representing ∼1–1.5% of the human genome, are regulated in the process during the first 2 days. These transcriptional profiles revealed genes coding for components of certain pathways, such as RAS oncogene family and G protein-coupled receptor signaling, to be differentially regulated during the early Th1 and Th2 cell differentiation. Importantly, numerous novel genes with unknown functions were identified. By using short-hairpin RNA knockdown, we show that a subset of these genes is regulated by IL-4 through STAT6 signaling. Furthermore, we demonstrate that one of the IL-4 regulated genes, NDFIP2, promotes IFN-γ production by the polarized human Th1 lymphocytes. Among the novel genes identified, there may be many factors that play a crucial role in the regulation of the differentiation process together with the previously known factors and are potential targets for developing therapeutics to modulate Th1 and Th2 responses.
Characterization of B7S3 as a Novel Negative Regulator of T Cells
Authors: Yang Yang , Liu Xikui K. , Nguyen Thang , Bishop Caroline , Graf Daniel , Dong Chen 
Published: April 2014

Abstract
T cell activation by APCs is regulated by B7-like costimulatory molecules. In this study, we describe a new B7 superfamily member, B7S3, with two differentially spliced isoforms expressed in lymphoid and nonlymphoid tissues. A soluble B7S3-Ig protein bound to professional APC constitutively as well as to activated but not naive T cells. B7S3-Ig treatment greatly inhibited T cell proliferation and IL-2 production. B7S3-Ig also reduced cytokine production by effector T cells. Interestingly, although human genome appears to contain a single-copy B7S3 homolog, the mouse B7S3 gene has 10 relatives within a 2-Mb region constituting a B7S3 gene family. This study identifies B7S3 as a novel negative regulator of T cells, and suggests evolutionarily divergent T cell regulation mechanisms in mammals.
Importance of the CD3γ Ectodomain Terminal β-Strand and Membrane Proximal Stalk in Thymic Development and Receptor Assembly
Authors: Touma Maki , Sun Zhen-Yu J. , Clayton Linda K. , Marissen Wilfred E. , Kruisbeek Ada M. , Wagner Gerhard , Reinherz Ellis L. 
Published: April 2014

Abstract
CD3εγ and CD3εδ are noncovalent heterodimers; each consists of Ig-like extracellular domains associated side-to-side via paired terminal β-strands that are linked to individual subunit membrane proximal stalk segments. CD3ε, CD3γ, and CD3δ stalks contain the RxCxxCxE motif. To investigate the functional importance of a CD3 stalk and terminal β-strand, we created a CD3γ double mutant CD3γC82S/C85S and a CD3γ β-strand triple mutant CD3γQ76S/Y78A/Y79A for use in retroviral transduction of lymphoid progenitors for comparison with CD3γwt. Although both mutant CD3γ molecules reduced association with CD3ε in CD3εγ heterodimers, CD3γQ76S/Y78A/Y79A abrogated surface TCR expression whereas CD3γC82S/C85S did not. Furthermore, CD3γC82S/C85S rescued thymic development in CD3γ−/− fetal thymic organ culture. However, the numbers of double-positive and single-positive thymocytes after CD3γC82S/C85S transduction were significantly reduced despite surface pre-TCR and TCR expression comparable to that of CD3γ−/− thymocytes transduced in fetal thymic organ culture with a retrovirus harboring CD3γwt cDNA. Furthermore, double-negative thymocyte development was perturbed with attenuated double-negative 3/double-negative 4 maturation and altered surface-expressed CD3εγ, as evidenced by the loss of reactivity with CD3γ N terminus-specific antisera. Single histidine substitution of either CD3γ stalk cysteine failed to restore CD3εγ association and conformation in transient COS-7 cell transfection studies. Thus, CD3γC82 and CD3γC85 residues likely are either reduced or form a tight intrachain disulfide loop rather than contribute to a metal coordination site in conjunction with CD3εC80 and CD3εC83. The implications of these results for CD3εγ and TCR structure and signaling function are discussed.
Messenger RNA Expression of IL-8, FOXP3, and IL-12β Differentiates Latent Tuberculosis Infection from Disease
Authors: Wu Bo , Huang Chunhong , Kato-Maeda Midori , Hopewell Philip C. , Daley Charles L. , Krensky Alan M. , Clayberger Carol 
Published: April 2014

Abstract
Differentiation of active from latent tuberculosis (TB) is a major challenge in the control of TB. In this study, PBMC from latent TB-infected subjects, TB patients, and tuberculin skin test-negative donors stimulated with the Mycobacterium tuberculosis (Mtb)-specific Ag, early secretory antigenic target 6, and mRNA for 45 immune-related genes was measured by quantitative real-time PCR. Univariate analysis showed significant differences in the expression of 10 genes (IFN-γ, FOXP3, IL-1α, IL-1β, IL-2, IL-6, IL-8, IL-12α, IL-12β, and IL-24) in PBMC from TB patients vs latent TB-infected subjects (p &lt; 0.01). Multivariate logistic regression and classification and regression tree analyses revealed that expression of three genes, IL-8, FOXP3, and IL-12β, is predictive for TB vs latent Mtb infection. Thus, measurement of Ag-specific expression of these three genes may offer a specific and noninvasive means of differentiating between latent Mtb infection and TB.
Induction of Protective Immunity to Listeria monocytogenes in Neonates
Authors: Kollmann Tobias R. , Reikie Brian , Blimkie Darren , Way Sing Sing , Hajjar Adeline M. , Arispe Kiea , Shaulov Angela , Wilson Christopher B. 
Published: April 2014

Abstract
Neonates suffer unduly from infections and also respond suboptimally to most commonly used vaccines. However, a CD8 T cell response can be elicited in neonates if the Ag is introduced into the cytoplasm of APCs. Listeria monocytogenes (Lm) targets the cytoplasm of APC and is a strong CD8 and CD4 Th1-promoting vaccine vehicle in adult mice. We hypothesized that an attenuated strain of Lm would be safe and induce long-lasting protective immunity, even in neonates. We found that neonatal mice immunized only once with the attenuated strain ΔactA-Lm developed robust primary and secondary CD8 and CD4 Th1 responses and were fully protected from lethal challenge with virulent wild-type Lm without the need for a booster immunization. Furthermore, ΔactA-Lm expressing a heterologous recombinant Ag induced a strong CD8 and Th1 memory response to that Ag. Based on these data, we propose that ΔactA-Lm or derivatives thereof might serve as a vaccine vehicle for neonatal immunization.