bluuebunny/crossref_metadata_2025_split huggingface dataset:
Functional Roles of TAP and Tapasin in the Assembly of M3-N-Formylated Peptide Complexes
Authors: Chun Taehoon , Grandea Andreas G. , Lybarger Lonnie , Forman James , Van Kaer Luc , Wang Chyung-Ru 
Published: April 2014

AbstractH2-M3 is a MHC class Ib molecule with a high propensity to bind N-formylated peptides. Due to the paucity of endogenous Ag, the majority of M3 is retained in the endoplasmic reticulum (ER). Upon addition of exogenous N-formylated peptides, M3 trafficks rapidly to the cell surface. To understand the mechanism underlying Ag presentation by M3, we examined the role of molecular chaperones in M3 assembly, particularly TAP and tapasin. M3-specific CTLs fail to recognize cells isolated from both TAP-deficient (TAPo) and tapasin-deficient mice, suggesting that TAP and tapasin are required for M3-restricted Ag presentation. Impaired M3 expression in TAPo mice is due to instability of the intracellular pool of M3. Addition of N-formylated peptides to TAPo cells stabilizes M3 in the ER and partially restores surface expression. Surprisingly, significant amounts of M3 are retained in the ER in tapasin-deficient mice, even in the presence of N-formylated peptides. Our results define the role of TAP and tapasin in the assembly of M3-peptide complexes. TAP is essential for stabilization of M3 in the ER, whereas tapasin is critical for loading of N-formylated peptides onto the intracellular pool of M3. However, neither TAP nor tapasin is required for ER retention of empty M3.
Differential Regulation of Mouse Germline Ig γ1 and ε Promoters by IL-4 and CD40
Authors: Mao Chun-sheng , Stavnezer Janet 
Published: April 2014

AbstractBefore Ig class switching, RNA transcription through the specific S regions undergoing recombination is induced by cytokines and other activators that induce and direct switching. The resulting germline (GL) transcripts are essential for switch recombination. To understand the differential regulation of mouse IgG1 and IgE, we compared the promoters for GL γ1 and ε transcripts. We addressed the question of why the promoter that regulates GL ε transcription is more responsive to IL-4 than the γ1 promoter and also why GL ε transcription is more dependent on IL-4 than is γ1 transcription. We found that the IL-4-responsive region of the GL ε promoter is more inducible than that of the γ1 promoter, although each promoter contains a binding site for the IL-4-inducible transcription factor Stat6, located immediately adjacent to a binding site for a basic region leucine zipper (bZip) family protein. However, the arrangement and sequences of the sites differ between the ε and γ1 promoters. The GL ε promoter binds Stat6 with a 10-fold higher affinity than does the γ1 promoter. Furthermore, the bZip elements of the two promoters bind different transcription factors, as the GL ε promoter binds and is activated by AP-1, whereas the γ1 promoter binds and is activated by activating transcription factor 2. C/EBPβ and C/EBPγ also bind the γ1 bZip element, although they inhibit rather than activate transcription. However, inhibition of promoter activity by C/EBPβ does not require the bZip element and may instead occur via inhibiting the activity of NF-κB.
Targeted Mutation of TNF Receptor I Rescues the RelA-Deficient Mouse and Reveals a Critical Role for NF-κB in Leukocyte Recruitment
Authors: Alcamo Elizabeth , Mizgerd Joseph P. , Horwitz Bruce H. , Bronson Rod , Beg Amer A. , Scott Martin , Doerschuk Claire M. , Hynes Richard O. , Baltimore David 
Published: April 2014

AbstractNF-κB binding sites are present in the promoter regions of many acute phase and inflammatory response genes, suggesting that NF-κB plays an important role in the initiation of innate immune responses. However, targeted mutations of the various NF-κB family members have yet to identify members responsible for this critical role. RelA-deficient mice die on embryonic day 15 from TNF-α-induced liver degeneration. To investigate the importance of RelA in innate immunity, we genetically suppressed this embryonic lethality by breeding the RelA deficiency onto a TNFR type 1 (TNFR1)-deficient background. TNFR1/RelA-deficient mice were born healthy, but were susceptible to bacterial infections and bacteremia and died within a few weeks after birth. Hemopoiesis was intact in TNFR1/RelA-deficient newborns, but neutrophil emigration to alveoli during LPS-induced pneumonia was severely reduced relative to that in wild-type or TNFR1-deficient mice. In contrast, radiation chimeras reconstituted with RelA or TNFR1/RelA-deficient hemopoietic cells were healthy and demonstrated no defect in neutrophil emigration during LPS-induced pneumonia. Analysis of RNA harvested from the lungs of mice 4 h after LPS insufflation revealed that the induction of several genes important for neutrophil recruitment to the lung was significantly reduced in TNFR1/RelA-deficient mice relative to that in wild-type or TNFR1-deficient mice. These results suggest that TNFR1-independent activation of RelA is essential in cells of nonhemopoietic origin during the initiation of an innate immune response.
Elevated Levels of Cyclooxygenase-2 in Antigen-Stimulated Mast Cells Is Associated with Minimal Activation of p38 Mitogen-Activated Protein Kinase
Authors: Hundley Thomas R. , Prasad Anjana R. , Beaven Michael A. 
Published: April 2014

AbstractWe have investigated possible factors that underlie changes in the production of eicosanoids after prolonged exposure of mast cells to Ag. Ag stimulation of cultured RBL-2H3 mast cells resulted in increased expression of cyclooxygenase (COX-2) protein and message. Other eicosanoid-related enzymes, namely COX-1, 5-lipoxygenase, and cytosolic phospholipase A2 were not induced. Activation of extracellular signal-regulated kinase, c-Jun N-terminal kinase, and p38 mitogen-activated protein (MAP) kinase preceded the induction of COX-2, whereas phosphatidylinositol 3′ kinase and its substrate, Akt, were constitutively activated in RBL-2H3 cells. Studies with pharmacologic inhibitors indicated that of these kinases, only p38 MAP kinase regulated expression of COX-2. The induction of COX-2 was blocked by the p38 MAP kinase inhibitor SB202190, even when added 12–16 h after stimulation with Ag when p38 MAP kinase activity had returned to near basal, but still minimally elevated, levels. Interestingly, expression of COX-2 as well as cytosolic phospholipase A2 and 5-lipoxygenase were markedly reduced by SB202190 in unstimulated cells. Collectively, the results imply that p38 MAP kinase regulates expression of eicosanoid-related enzymes, passively or actively, at very low levels of activity in RBL-2H3 cells. Also, comparison with published data suggest that different MAP kinases regulate induction of COX-2 in inflammatory cells of different and even similar phenotype and suggest caution in extrapolating results from one type of cell to another.
RANTES-Induced Chemokine Cascade in Dendritic Cells
Authors: Fischer Falko R. , Luo Yi , Luo Moli , Santambrogio Laura , Dorf Martin E. 
Published: April 2014

AbstractDendritic cells (DC) are the most potent APCs and the principal activators of naive T cells. We now report that chemokines can serve as activating agents for immature DC. Murine bone marrow-derived DC respond to the CC chemokine RANTES (10–100 ng/ml) by production of proinflammatory mediators. RANTES induces rapid expression of transcripts for the CXC chemokines KC and macrophage inflammatory protein (MIP)-2, the CC chemokines MIP-1β and MIP-1α, and the cytokines TNF-α and IL-6. Synthesis of KC, IL-6, and TNF-α proteins were also demonstrated. After 4 h, autoinduction of RANTES transcripts was observed. These responses are chemokine specific. Although DC demonstrated weak responses to eotaxin, DC failed to respond to other chemokines including KC, MIP-2, stromal-derived factor-1α, MIP-1β, MIP-1α, monocyte chemoattractant protein-1, T cell activation gene 3, or thymus-derived chemotactic agent 4. In addition, RANTES treatment up-regulated expression of an orphan chemokine receptor termed Eo1. Chemokine induction was also observed after treatment of splenic DC and neonatal microglia with RANTES, but not after treatment of thymocytes or splenocytes depleted of adherent cells. TNF-α-treated DC lose responsiveness to RANTES. DC from mice deficient for CCR1, CCR3, and CCR5 respond to RANTES, indicating that none of these receptors are exclusively used to initiate the chemokine cascade. RANTES-mediated chemokine amplification in DC may prolong inflammatory responses and shape the microenvironment, potentially enhancing acquired and innate immune responses.
IL-13 Induces Airways Hyperreactivity Independently of the IL-4Rα Chain in the Allergic Lung
Authors: Mattes Joerg , Yang Ming , Siqueira Ana , Clark Kris , MacKenzie Jason , McKenzie Andrew N. J. , Webb Dianne C. , Matthaei Klaus I. , Foster Paul S. 
Published: April 2014

AbstractThe potent spasmogenic properties of IL-13 have identified this molecule as a potential regulator of airways hyperreactivity (AHR) in asthma. Although IL-13 is thought to primarily signal through the IL-13Rα1-IL-4Rα complex, the cellular and molecular components employed by this cytokine to induce AHR in the allergic lung have not been identified. By transferring OVA-specific CD4+ T cells that were wild type (IL-13+/+ T cells) or deficient in IL-13 (IL-13−/− T cells) to nonsensitized mice that were then challenged with OVA aerosol, we show that T cell-derived IL-13 plays a key role in regulating AHR, mucus hypersecretion, eotaxin production, and eosinophilia in the allergic lung. Moreover, IL-13+/+ T cells induce these features (except mucus production) of allergic disease independently of the IL-4Rα chain. By contrast, IL-13+/+ T cells did not induce disease in STAT6-deficient mice. This shows that IL-13 employs a novel component of the IL-13 receptor signaling system that involves STAT6, independently of the IL-4Rα chain, to modulate pathogenesis. We show that this novel pathway for IL-13 signaling is dependent on T cell activation in the lung and is critically linked to downstream effector pathways regulated by eotaxin and STAT6.
Adenoviral Augmentation of Elafin Protects the Lung Against Acute Injury Mediated by Activated Neutrophils and Bacterial Infection
Authors: Simpson A. John , Wallace William A. H. , Marsden Mark E. , Govan John R. W. , Porteous David J. , Haslett Chris , Sallenave Jean-Michel 
Published: April 2014

AbstractDuring acute pulmonary infection, tissue injury may be secondary to the effects of bacterial products or to the effects of the host inflammatory response. An attractive strategy for tissue protection in this setting would combine antimicrobial activity with inhibition of human neutrophil elastase (HNE), a key effector of neutrophil-mediated tissue injury. We postulated that genetic augmentation of elafin (an endogenous inhibitor of HNE with intrinsic antimicrobial activity) could protect the lung against acute inflammatory injury without detriment to host defense. A replication-deficient adenovirus encoding elafin cDNA significantly protected A549 cells against the injurious effects of both HNE and whole activated human neutrophils in vitro. Intratracheal replication-deficient adenovirus encoding elafin cDNA significantly protected murine lungs against injury mediated by Pseudomonas aeruginosa in vivo. Genetic augmentation of elafin therefore has the capacity to protect the lung against the injurious effects of both bacterial pathogens resistant to conventional antibiotics and activated neutrophils.
Cutting Edge: The Nucleotide Receptor P2X7 Contains Multiple Protein- and Lipid-Interaction Motifs Including a Potential Binding Site for Bacterial Lipopolysaccharide
Authors: Denlinger Loren C. , Fisette Philip L. , Sommer Julie A. , Watters Jyoti J. , Prabhu Usha , Dubyak George R. , Proctor Richard A. , Bertics Paul J. 
Published: April 2014

Abstract
The nucleotide receptor P2X7 has been shown to modulate LPS-induced macrophage production of numerous inflammatory mediators. Although the C-terminal portion of P2X7 is thought to be essential for multiple receptor functions, little is known regarding the structural motifs that lie within this region. We show here that the P2X7 C-terminal domain contains several apparent protein-protein and protein-lipid interaction motifs with potential importance to macrophage signaling and LPS action. Surprisingly, P2X7 also contains a conserved LPS-binding domain. In this report, we demonstrate that peptides derived from this P2X7 sequence bind LPS in vitro. Moreover, these peptides neutralize the ability of LPS to activate the extracellular signal-regulated kinases (ERK1, ERK2) and to promote the degradation of the inhibitor of κB-α isoform (IκB-α) in RAW 264.7 macrophages. Collectively, these data suggest that the C-terminal domain of P2X7 may directly coordinate several signal transduction events related to macrophage function and LPS action.
Somatic Hypermutation and Selection of B Cells in Thymic Germinal Centers Responding to Acetylcholine Receptor in Myasthenia Gravis
Authors: Sims Gary P. , Shiono Hiroyuki , Willcox Nick , Stott David I. 
Published: April 2014

AbstractThe muscle weakness in myasthenia gravis (MG) is mediated by autoantibodies against the nicotinic acetylcholine receptor (AChR) at the neuromuscular junction. Production of these pathogenic autoantibodies is believed to be associated with germinal centers (GC) and anti-AChR-secreting plasma cells in the hyperplastic thymus of patients with early onset MG (EOMG). Here, we describe the repertoire of rearranged heavy chain V genes and their clonal origins in GC from a typical EOMG patient. Three hundred fifteen rearranged Ig VH genes were amplified, cloned, and sequenced from sections of four thymic GC containing AChR-specific B cells. We found that thymic GC contain a remarkably heterogeneous population of B cells. Both naive and circulating memory B cells undergo Ag-driven clonal proliferation, somatic hypermutation, and selection. Numerous B cell clones were present, with no individual clone dominating the response. Comparisons of B cell clonal sequences from different GC and known anti-AChR Abs from other patients showed convergent mutations in the complementarity determining regions. These results are consistent with AChR driving an ongoing GC response in the thymus of EOMG patients. This is the first detailed analysis of B cell clones in human GC responding to a defined protein Ag, and the response we observed may reflect the effects of chronic stimulation by autoantigen.
Signaling Lymphocytic Activation Molecule Is Expressed on Mature CD83+ Dendritic Cells and Is Up-Regulated by IL-1β
Authors: Kruse Monika , Meinl Edgar , Henning Golo , Kuhnt Christine , Berchtold Susanne , Berger Thomas , Schuler Gerold , Steinkasserer Alexander 
Published: April 2014

AbstractSignaling lymphocyte activation molecule (SLAM), a 70-kDa costimulatory molecule that mediates CD28-independent proliferation of T cells and IFN-γ production, has been identified on human T cells, immature thymocytes, and a subset of B cells. We have found that SLAM is expressed on mature but not immature dendritic cells (DC). However, the SLAM-associated protein, is missing in DC. SLAM surface expression is strongly up-regulated by IL-1β. Addition of IL-1β to the DC maturation mixture also increases the stimulatory properties of DC. These findings provide a new marker for DC maturation and help to explain two areas of DC biology. First, SLAM is a receptor for the measles virus, previously shown to infect DC. Second, SLAM could possibly contribute to the enhanced immunostimulatory functions of DC that are observed following the addition of IL-1.
Inducible Costimulator Regulates Th2-Mediated Inflammation, but Not Th2 Differentiation, in a Model of Allergic Airway Disease
Authors: Tesciuba Amanda G. , Subudhi Sumit , Rother Russell P. , Faas Susan J. , Frantz Aric M. , Elliot David , Weinstock Joel , Matis Louis A. , Bluestone Jeffrey A. , Sperling Anne I. 
Published: April 2014

Abstract
A novel costimulatory molecule expressed on activated T cells, inducible costimulator (ICOS), and its ligand, B7-related protein-1 (B7RP-1), were recently identified. ICOS costimulation leads to the induction of Th2 cytokines without augmentation of IL-2 production, suggesting a role for ICOS in Th2 cell differentiation and expansion. In the present study, a soluble form of murine ICOS, ICOS-Ig, was used to block ICOS/B7RP-1 interactions in a Th2 model of allergic airway disease. In this model, mice are sensitized with inactivated Schistosoma mansoni eggs and are subsequently challenged with soluble S. mansoni egg Ag directly in the airways. Treatment of C57BL/6 mice with ICOS-Ig during sensitization and challenge attenuated airway inflammation, as demonstrated by a decrease in cellular infiltration into the lung tissue and airways, as well as by a decrease in local IL-5 production. These inhibitory effects were not due to a lack of T cell priming nor to a defect in Th2 differentiation. In addition, blockade of ICOS/B7RP-1 interactions during ex vivo restimulation of lung Th2 effector cells prevented cytokine production. Thus, blockade of ICOS signaling can significantly reduce airway inflammation without affecting Th2 differentiation in this model of allergic airway disease.
IFN-γ-Dependent and -Independent Initiation of Switch Recombination by NK Cells
Authors: Gao Ning , Dang Tam , Yuan Dorothy 
Published: April 2014

Abstract
We have examined the effect of IL-2-propagated NK or NK-T cells on each of the steps required for B cell switch recombination leading to IgG2a production. The results indicate that NK cells, on their own and in the absence of IFN-γ, can induce germline transcription in resting, IgG− B lymphocytes from the γ2a locus as well as mRNA for activation-induced cytidine deaminase (AID) via a process that requires cell-cell interactions. The results also show that, in contrast to induction by T cells, activation by NK cells does not involve CD40-CD40 ligand interactions and does not extend to the induction of Iγ1 transcription. Furthermore, in contrast to stimulation by LPS and IFN-γ or by T cells, the activation events initiated by NK cells do not result in significant synthesis of functional γ2a mRNA in resting B lymphocytes even in the presence of IFN-γ. Thus, induction of germline and AID transcripts are necessary but not sufficient events for functional switching to IgG2a. These experiments, showing that NK cells themselves cannot induce IgG2a production but can polyclonally program B lymphocytes so that they preferentially switch to this isotype may explain how activated NK cells can skew the Ag-specific immune response toward IgG2a. The findings also provide further demonstration of the definitive yet limited extent of how a non-Ag-specific component of the innate system can modulate the direction of the adaptive immune response.
Combinatorial Peptide Libraries and Biometric Score Matrices Permit the Quantitative Analysis of Specific and Degenerate Interactions Between Clonotypic TCR and MHC Peptide Ligands
Authors: Zhao Yingdong , Gran Bruno , Pinilla Clemencia , Markovic-Plese Silva , Hemmer Bernhard , Tzou Abraham , Whitney Laurie Ward , Biddison William E. , Martin Roland , Simon Richard 
Published: April 2014

Abstract
The interaction of TCRs with MHC peptide ligands can be highly flexible, so that many different peptides are recognized by the same TCR in the context of a single restriction element. We provide a quantitative description of such interactions, which allows the identification of T cell epitopes and molecular mimics. The response of T cell clones to positional scanning synthetic combinatorial libraries is analyzed with a mathematical approach that is based on a model of independent contribution of individual amino acids to peptide Ag recognition. This biometric analysis compares the information derived from these libraries composed of trillions of decapeptides with all the millions of decapeptides contained in a protein database to rank and predict the most stimulatory peptides for a given T cell clone. We demonstrate the predictive power of the novel strategy and show that, together with gene expression profiling by cDNA microarrays, it leads to the identification of novel candidate autoantigens in the inflammatory autoimmune disease, multiple sclerosis.
Expression of TNF-α by Herpes Simplex Virus-Infected Macrophages Is Regulated by a Dual Mechanism: Transcriptional Regulation by NF-κB and Activating Transcription Factor 2/Jun and Translational Regulation Through the AU-Rich Region of the 3′ Untranslated Region
Authors: Paludan Søren R. , Ellermann-Eriksen Svend , Kruys Veronique , Mogensen Søren C. 
Published: April 2014

Abstract
Here we have investigated the regulation of TNF-α expression in macrophages during HSV-2 infection. Despite a low basal level of TNF-α mRNA present in resting macrophages, no TNF-α protein is detectable. HSV-2 infection marginally increases the level of TNF-α mRNA and protein in resting macrophages, whereas a strong increase is observed in IFN-γ-activated cells infected with the virus. By reporter gene assay it was found that HSV infection augments TNF-α promoter activity. Moreover, treatment of the cells with actinomycin D, which totally blocked mRNA synthesis, only partially prevented accumulation of TNF-α protein, indicating that the infection lifts a block on translation of TNF-α mRNA. EMSA analysis showed that specific binding to the κB#3 site of the murine TNF-α promoter was induced within 1 h after infection and persisted beyond 5 h where TNF-α expression is down-modulated. Binding to the cAMP responsive element site was also induced but more transiently with kinetics closely following activation of the TNF-α promoter. Inhibitors against either NF-κB activation or the activating transcription factor 2 kinase p38 abrogated TNF-α expression, showing a requirement for both signals for activation of the promoter. This observation was corroborated by reporter gene assays. As to the translational regulation of TNF-α, the AU-rich sequence in the 3′ untranslated region of the mRNA was found to be responsible for this control because deletion of this region renders mRNA constitutively translationable. These results show that TNF-α production is induced by HSV-2 in macrophages through both transcriptional and translational regulation.
Dynamic Antigen Presentation Patterns of Listeria monocytogenes-Derived CD8 T Cell Epitopes In Vivo
Authors: Škoberne Mojca , Holtappels Rafaela , Hof Herbert , Geginat Gernot 
Published: April 2014

Abstract
Little information exists regarding the presentation of antigenic peptides in infected tissues. In this study the in vivo presentation of four different CD8 T cell epitopes of Listeria monocytogenes was monitored. Peptide presentation was measured by a new, highly sensitive, ex vivo Ag presentation assay that was based on the testing of freshly isolated cells from infected spleens with peptide-specific CD8 T cell lines in an IFN-γ-specific ELISPOT assay. Remarkably, the peptide presentation pattern of splenocytes and that of macrophages purified from spleens of L. monocytogenes-infected mice were different from those of in vitro infected macrophage-like cell lines. The in vivo Ag presentation pattern of splenocytes also exhibited dynamic changes during the first 48 h of infection. In vivo peptide presentation at later time points postinfection was biased toward immunodominant CD8 T cell epitopes, while at an early time point, 6 h postinfection, subdominant and dominant CD8 T cell epitopes were presented with similar strength. In summary, our studies show that Ag presentation during an infection is a highly dynamic process that only can be fully appreciated by the study of cells infected in their physiological environment.