bluuebunny/crossref_metadata_2025_split huggingface dataset:
TCR Comodulation of Nonengaged TCR Takes Place by a Protein Kinase C and CD3γ Di-Leucine-Based Motif-Dependent Mechanism
Authors: Bonefeld Charlotte Menné , Rasmussen Anette B. , Lauritsen Jens Peter H. , von Essen Marina , Ødum Niels , Andersen Peter S. , Geisler Carsten 
Published: April 2014

Abstract
One of the earliest events following TCR triggering is TCR down-regulation. However, the mechanisms behind TCR down-regulation are still not fully known. Some studies have suggested that only directly triggered TCR are internalized, whereas others studies have indicated that, in addition to triggered receptors, nonengaged TCR are also internalized (comodulated). In this study, we used transfected T cells expressing two different TCR to analyze whether comodulation took place. We show that TCR triggering by anti-TCR mAb and peptide-MHC complexes clearly induced internalization of nonengaged TCR. By using a panel of mAb against the Tiβ chain, we demonstrate that the comodulation kinetics depended on the affinity of the ligand. Thus, high-affinity mAb (KD = 2.3 nM) induced a rapid but reversible comodulation, whereas low-affinity mAb (KD = 6200 nM) induced a slower but more permanent type of comodulation. Like internalization of engaged TCR, comodulation was dependent on protein tyrosine kinase activity. Finally, we found that in contrast to internalization of engaged TCR, comodulation was highly dependent on protein kinase C activity and the CD3γ di-leucine-based motif. Based on these observations, a physiological role of comodulation is proposed and the plausibility of the TCR serial triggering model is discussed.
Generation and Function of Reactive Oxygen Species in Dendritic Cells During Antigen Presentation
Authors: Matsue Hiroyuki , Edelbaum Dale , Shalhevet David , Mizumoto Norikatsu , Yang Chendong , Mummert Mark E. , Oeda Junichi , Masayasu Hiroyuki , Takashima Akira 
Published: April 2014

Abstract
Although reactive oxygen species (ROS) have long been considered to play pathogenic roles in various disorders, this classic view is now being challenged by the recent discovery of their physiological roles in cellular signaling. To determine the immunological consequence of pharmacological disruption of endogenous redox regulation, we used a selenium-containing antioxidant compound ebselen known to modulate both thioredoxin and glutaredoxin pathways. Ebselen at 5–20 μM inhibited Con A-induced proliferation and cytokine production by the HDK-1 T cell line as well as the LPS-triggered cytokine production by XS52 dendritic cell (DC) line. Working with the in vitro-reconstituted Ag presentation system composed of bone marrow-derived DC, CD4+ T cells purified from DO11.10 TCR-transgenic mice and OVA peptide (serving as Ag), we observed that 1) both T cells and DC elevate intracellular oxidation states upon Ag-specific interaction; 2) ebselen significantly inhibits ROS production in both populations; and 3) ebselen at 5–20 μM inhibits DC-induced proliferation and cytokine production by T cells as well as T cell-induced cytokine production by DC. Thus, Ag-specific, bidirectional DC-T cell communication can be blocked by interfering with the redox regulation pathways. Allergic contact hypersensitivity responses in BALB/c mice to oxazolone, but not irritant contact hypersensitivity responses to croton oil, were suppressed significantly by postchallenge treatment with oral administrations of ebselen (100 mg/kg per day). These results provide both conceptual and technical frameworks for studying ROS-dependent regulation of DC-T cell communication during Ag presentation and for testing the potential utility of antioxidants for the treatment of immunological disease.
TCR-Mediated Notch Signaling Regulates Proliferation and IFN-γ Production in Peripheral T Cells
Authors: Palaga Tanapat , Miele Lucio , Golde Todd E. , Osborne Barbara A. 
Published: April 2014

Abstract
Notch genes encode membrane receptors that regulate cell fate decisions in metazoa. Notch receptors and ligands are expressed in developing lymphoid tissue and mature lymphocytes and the role of Notch signaling in early T and B cell development has been studied extensively. However, its contribution to mature T cell function is unknown. TCR-mediated T cell activation is a fundamental process of the adaptive immune system that has been studied for decades; however, the details of this process are incompletely understood. In this study, we present evidence that Notch is required for TCR-mediated activation of peripheral T cells. Inhibition of Notch activation dramatically decreases T cell proliferation in both CD4 and CD8 cells and blocks both NF-κB activity and IFN-γ production in peripheral T cells. Our data reveal a new, nondevelopmental function of Notch as a previously unknown key link in peripheral T cell activation and cytokine secretion.
Differential Recognition of Altered Peptide Ligands Distinguishes Two Functionally Discordant (Arthritogenic and Nonarthritogenic) Autoreactive T Cell Hybridoma Clones
Authors: Buzás Edit I. , Hanyecz Anita , Murad Yanal , Hudecz Ferenc , Rajnavölgyi Eva , Mikecz Katalin , Glant Tibor T. 
Published: April 2014

Abstract
Intravenous injection of a cartilage proteoglycan (aggrecan)-specific Th1 hybridoma clone 5/4E8 induced joint lesions similar to those seen in either primary or adoptively transferred arthritis in BALB/c mice. A sister clone, TA20, recognizing the same peptide epitope of human aggrecan and using the same Vβ4 and Vα1 segments, failed to induce joint inflammation. This study examines the fine epitope specificities of these two clones. Both 5/4E8 and TA20 hybridomas were generated using T cells from the same arthritic animal that has been immunized with human aggrecan, and both clones recognized peptides containing a consensus GRVRVNSAY sequence. However, flanking regions outside this nonapeptide sequence region had differential impact on peptide recognition by the two clones. Similarly, when single amino acid substitutions were introduced to the consensus sequence, significant differences were detected in the epitope recognition patterns of the T cell hybridomas. The 5/4E8 hybridoma showed greater flexibility in recognition, including a higher responsiveness to the corresponding self (mouse) aggrecan peptide, and produced more inflammatory cytokines (IFN-γ and TNF-α), whereas hybridoma TA20 produced IL-5 in response to either human or mouse self peptide stimulation. These results demonstrate that, within the pool of immunodominant (foreign) peptide-activated lymphocytes, marked individual differences of degeneracy exist in T cell recognition, with possible implications to autopathogenic T cell functions.
Characterization of the CD200 Receptor Family in Mice and Humans and Their Interactions with CD200
Authors: Wright Gavin J. , Cherwinski Holly , Foster-Cuevas Mildred , Brooke Gary , Puklavec Michael J. , Bigler Mike , Song Yaoli , Jenmalm Maria , Gorman Dan , McClanahan Terri , Liu Man-Ru , Brown Marion H. , Sedgwick Jonathon D. , Phillips Joseph H. , Barclay A. Neil 
Published: April 2014

Abstract
CD200 (OX2) is a broadly distributed cell surface glycoprotein that interacts with a structurally related receptor (CD200R) expressed on rodent myeloid cells and is involved in regulation of macrophage function. We report the first characterization of human CD200R (hCD200R) and define its binding characteristics to hCD200. We also report the identification of a closely related gene to hCD200R, designated hCD200RLa, and four mouse CD200R-related genes (termed mCD200RLa-d). CD200, CD200R, and CD200R-related genes were closely linked in humans and mice, suggesting that these genes arose by gene duplication. The distributions of the receptor genes were determined by quantitative RT-PCR, and protein expression was confirmed by a set of novel mAbs. The distribution of mouse and human CD200R was similar, with strongest labeling of macrophages and neutrophils, but also other leukocytes, including monocytes, mast cells, and T lymphocytes. Two mCD200 receptor-like family members, designated mCD200RLa and mCD200RLb, were shown to pair with the activatory adaptor protein, DAP12, suggesting that these receptors would transmit strong activating signals in contrast to the apparent inhibitory signal delivered by triggering the CD200R. Despite substantial sequence homology with mCD200R, mCD200RLa and mCD200RLb did not bind mCD200, and presently have unknown ligands. The CD200 receptor gene family resembles the signal regulatory proteins and killer Ig-related receptors in having receptor family members with potential activatory and inhibitory functions that may play important roles in immune regulation and balance. Because manipulation of the CD200-CD200R interaction affects the outcome of rodent disease models, targeting of this pathway may have therapeutic utility.
Candida albicans Induces Selectively Transcriptional Activation of Cyclooxygenase-2 in HeLa Cells: Pivotal Roles of Toll-Like Receptors, p38 Mitogen-Activated Protein Kinase, and NF-κB
Authors: Deva Rupal , Shankaranarayanan Pattabhiraman , Ciccoli Roberto , Nigam Santosh 
Published: April 2014

Abstract
Candidiasis, in its mucocutaneous form as well as in an invasive form, is frequently associated with high morbidity. PGE2, which is generated by enzymatic activity of cyclooxygenases (COXs) 1 and 2, has been shown to trigger morphogenesis in Candida albicans. In the present study, we investigated whether C. albicans altered COX-2 expression in HeLa cells. RT-PCR and Western blot analyses revealed a time-dependent biphasic behavior of COX-2 mRNA expression and COX-2 protein level. COX-1 protein remained unaffected. Neutralization with Abs against Toll-like receptors (TLR) 2 and 4 inhibited the Candida-induced production of PGE2, suggesting a vital role for TLRs in the recognition and signaling in mammalian cells upon infection with C. albicans. Transient transfections with COX-2 promoter-luciferase construct and various inhibitors of mitogen-activated protein kinases (MAPK), such as protein kinase C (PKC) inhibitor GF203190X, p38MAPK inhibitor SB203109, and extracellular-regulated kinases 1 and 2 inhibitor PD98509 showed that C. albicans up-regulates selectively COX-2, but not COX-1, through p38MAPK and PKC pathways. No involvement of other stress kinases, e.g., c-Jun NH2-terminal kinase and extracellular-regulated kinases 1 and 2, was observed. Transient transfection of NF-κB promoter construct and dominant negative plasmid of IκBβ kinase showed that COX-2 transcription is mediated through p38MAPK and NF-κB pathways. That NF-κB up-regulates p38MAPK is novel and is in contradiction to earlier reports in which NF-κB was shown to inhibit p38MAPK. In conclusion, multiple converging signaling pathways, involving TLRs followed by PKC, p38MAPK, and/or NF-κB, are triggered by C. albicans in activation of COX-2 gene.
Killer Cell Ig-Like Receptor and Leukocyte Ig-Like Receptor Transgenic Mice Exhibit Tissue- and Cell-Specific Transgene Expression
Authors: Belkin Danny , Torkar Michaela , Chang Chiwen , Barten Roland , Tolaini Mauro , Haude Anja , Allen Rachel , Wilson Michael J. , Kioussis Dimitris , Trowsdale John 
Published: April 2014

Abstract
To generate an experimental model for exploring the function, expression pattern, and developmental regulation of human Ig-like activating and inhibitory receptors, we have generated transgenic mice using two human genomic clones: 52N12 (a 150-Kb clone encompassing the leukocyte Ig-like receptor (LILR)B1 (ILT2), LILRB4 (ILT3), and LILRA1 (LIR6) genes) and 1060P11 (a 160-Kb clone that contains ten killer cell Ig-like receptor (KIR) genes). Both the KIR and LILR families are encoded within the leukocyte receptor complex, and are involved in immune modulation. We have also produced a novel mAb to LILRA1 to facilitate expression studies. The LILR transgenes were expressed in a similar, but not identical, pattern to that observed in humans: LILRB1 was expressed in B cells, most NK cells, and a small number of T cells; LILRB4 was expressed in a B cell subset; and LILRA1 was found on a ring of cells surrounding B cell areas on spleen sections, consistent with other data showing monocyte/macrophage expression. KIR transgenic mice showed KIR2DL2 expression on a subset of NK cells and T cells, similar to the pattern seen in humans, and expression of KIR2DL4, KIR3DS1, and KIR2DL5 by splenic NK cells. These observations indicate that linked regulatory elements within the genomic clones are sufficient to allow appropriate expression of KIRs in mice, and illustrate that the presence of the natural ligands for these receptors, in the form of human MHC class I proteins, is not necessary for the expression of the KIRs observed in these mice.
Tax and M1 Peptide/HLA-A2-Specific Fabs and T Cell Receptors Recognize Nonidentical Structural Features on Peptide/HLA-A2 Complexes
Authors: Biddison William E. , Turner Richard V. , Gagnon Susan J. , Lev Avital , Cohen Cyril J. , Reiter Yoram 
Published: April 2014

Abstract
Both TCRs and Ab molecules are capable of MHC-restricted recognition of peptide/MHC complexes. However, such MHC restriction is the predominant mode of recognition by T cells, but is extremely rare for B cells. The present study asks whether the dichotomy in Ag recognition modes of T and B cells could be due to fundamental differences in the methods by which TCRs and Abs recognize peptide/MHC complexes. We have compared MHC and peptide recognition by panels of CTL lines specific for the Tax and M1 peptides presented by HLA-A2 plus Tax and M1 peptide/HLA-A2-specific human Fabs that were selected from a naive phage display library. Collectively, the results indicate both striking similarities and important differences between Fab and TCR recognition of MHC and peptide components of the Tax and M1/HLA-A2 complexes. These findings suggest that these two classes of immunoreceptors have solved the problem of specific recognition of peptide/MHC complexes by nonidentical mechanisms. This conclusion is important in part because it indicates that Ab engineering approaches could produce second-generation Ab molecules that more closely mimic TCR fine specificity. Such efforts may produce more efficacious diagnostic and therapeutic agents.
Herpes Simplex Virus Type 1 Targets the MHC Class II Processing Pathway for Immune Evasion
Authors: Neumann Jürgen , Eis-Hübinger Anna Maria , Koch Norbert 
Published: April 2014

Abstract
HSV type 1 (HSV-1) has evolved numerous strategies for modifying immune responses that protect against infection. Important targets of HSV-1 infection are the MHC-encoded peptide receptors. Previous studies have shown that a helper T cell response and Ab production play important roles in controlling HSV-1 infection. The reduced capacity of infected B cells to stimulate CD4+ T cells is beneficial for HSV-1 to evade immune defenses. We investigated the impact of HSV-1 infection on the MHCII processing pathway, which is critical to generate CD4+ T cell help. HSV-1 infection targets the molecular coplayers of MHC class II processing, HLA-DR (DR), HLA-DM (DM), and invariant chain (Ii). HSV-1 infection strongly reduces expression of Ii, which impairs formation of SDS-resistant DR-peptide complexes. Residual activity of the MHC class II processing pathway is diminished by viral envelope glycoprotein B (gB). Binding of gB to DR competes with binding to Ii. In addition, we found gB associated with DM molecules. Both, gB-associated DR and DM heterodimers are exported from the endoplasmic reticulum, as indicated by carbohydrate maturation. Evaluation of DR, DM, and gB subcellular localization revealed abundant changes in intracellular distribution. DR-gB complexes are localized in subcellular vesicles and restrained from cell surface expression.
Dominating IgE-Binding Epitope of Bet v 1, the Major Allergen of Birch Pollen, Characterized by X-ray Crystallography and Site-Directed Mutagenesis
Authors: Spangfort Michael D. , Mirza Osman , Ipsen Henrik , van Neerven R. J. Joost , Gajhede Michael , Larsen Jørgen N. 
Published: April 2014

Abstract
Specific allergy vaccination is an efficient treatment for allergic disease; however, the development of safer vaccines would enable a more general use of the treatment. Determination of molecular structures of allergens and allergen-Ab complexes facilitates epitope mapping and enables a rational approach to the engineering of allergen molecules with reduced IgE binding. In this study, we describe the identification and modification of a human IgE-binding epitope based on the crystal structure of Bet v 1 in complex with the BV16 Fab′ fragment. The epitope occupies ∼10% of the molecular surface area of Bet v 1 and is clearly conformational. A synthetic peptide representing a sequential motif in the epitope (11 of 16 residues) did not inhibit the binding of mAb BV16 to Bet v 1, illustrating limitations in the use of peptides for B cell epitope characterization. The single amino acid substitution, Glu45-Ser, was introduced in the epitope and completely abolished the binding of mAb BV16 to the Bet v 1 mutant within a concentration range 1000-fold higher than wild type. The mutant also showed up to 50% reduction in the binding of human polyclonal IgE, demonstrating that glutamic acid 45 is a critical amino acid also in a major human IgE-binding epitope. By solving the three-dimensional crystal structure of the Bet v 1 Glu45-Ser mutant, it was shown that the change in immunochemical activity is directly related to the Glu45-Ser substitution and not to long-range structural alterations or collapse of the Bet v 1 mutant tertiary structure.
Immunoglobulin μ Heavy Chains Do Not Mediate Tyrosine Phosphorylation of Igα from the ER-cis-Golgi
Authors: Mielenz Dirk , Ruschel Anja , Vettermann Christian , Jäck Hans-Martin 
Published: April 2014

Abstract
Signals delivered by Ig receptors guide the development of functional B lymphocytes. For example, clonal expansion of early μ heavy chain (μHC)-positive pre-B cells requires the assembly of a signal-competent pre-B cell receptor complex (pre-BCR) consisting of a μHC, a surrogate L chain, and the signal dimer Igαβ. However, only a small fraction of the pre-BCR is transported to the cell surface, suggesting that pre-BCR signaling initiates already from an intracellular compartment, e.g., the endoplasmic reticulum (ER). The finding that differentiation of pre-B cells and allelic exclusion at the IgH locus take place in surrogate L chain-deficient mice further supports the presence of a μHC-mediated intracellular signal pathway. To determine whether a signal-competent Ig complex can already be assembled in the ER, we analyzed the consequence of pervanadate on tyrosine phosphorylation of Igα in J558L plasmacytoma and 38B9 pre-B cells transfected with either a transport-competent IgL chain-pairing or an ER-retained nonpairing μHC. Flow cytometry, combined Western blot-immunoprecipitation-kinase assays, and confocal microscopy revealed that both the nonpairing and pairing μHC assembled with the Igαβ dimer; however, in contrast to a pairing μHC, the nonpairing μHC was retained in the ER-cis-Golgi compartment, and neither colocalized with the src kinase lyn nor induced tyrosine phosphorylation of Igα after pervanadate treatment of cells. On the basis of these findings, we propose that a signal-competent Ig complex consisting of μHC, Igαβ, and associated kinases is assembled in a post-ER compartment, thereby supporting the idea that a pre-BCR must be transported to the cell surface to initiate pre-BCR signaling.
Measles Virus Infection Induces Chemokine Synthesis by Neurons
Authors: Patterson Catherine E. , Daley John K. , Echols Lisa A. , Lane Thomas E. , Rall Glenn F. 
Published: April 2014

Abstract
The role that neurons play in the induction of the immune response following CNS viral infection is poorly understood, largely owing to the belief that these cells are immunologically quiescent. In this report, we show that virus infection of neurons results in the synthesis of proinflammatory chemokines, which are early and important mediators of leukocyte recruitment to sites of viral infection. For these studies, a transgenic mouse model of neuron-restricted measles virus (MV) infection was used. Inoculation of immunocompetent and immunodeficient transgenic adult mice resulted in CNS induction of the mRNAs encoding IFN-γ inducible protein of 10 kD, monokine inducible by γ and RANTES. Colocalization of chemokine proteins with MV-infected neurons was detected by immunofluorescence in infected brain sections. Both IFN-γ inducible protein 10 kD and RANTES were also induced in MV-infected primary hippocampal neurons cultured from transgenic embryos, as shown by RNase protection assay, confocal microscopy, and ELISA. Interestingly, neuronal infection with another RNA virus (lymphocytic choriomeningitis virus) was not associated with induction of these chemokines. In immunocompetent mice, chemokine synthesis preceded the infiltration of T lymphocytes, and chemokine ablation by neutralizing Abs resulted in a 20–50% reduction in the number of infiltrating lymphocytes. Collectively, these data indicate that neurons play an important role in the recruitment of a protective antiviral response to the CNS following viral infection, although such a role may be virus type-dependent.
Reactivation of Latent Tuberculosis Infection in TNF-Deficient Mice
Authors: Botha Tania , Ryffel Bernhard 
Published: April 2014

Abstract
TNF-deficient mice are highly susceptible to Mycobacterium tuberculosis H37Rv infection. Here we asked whether TNF is required for postinfectious immunity in aerosol-infected mice. Chemotherapy for 4 wk commencing 2 wk postinfection reduced CFU to undetectable levels. While wild-type mice had a slight rise in CFU, but controlled infection upon cessation of chemotherapy, TNF-deficient mice developed reactivation of infection with high bacterial loads in lungs, spleen, and liver, which was fatal within 13–18 wk. The increased susceptibility of TNF-deficient mice was accompanied by diminished recruitment and activation of T cells and macrophages into the lung, with defective granuloma formation and reduced inducible NO synthase expression. Reduced chemokine production in the lung might explain suboptimal recruitment and activation of T cells and uncontrolled infection. Therefore, despite a massive reduction of the mycobacterial load by chemotherapy, TNF-deficient mice were unable to compensate and mount a protective immune response. In conclusion, endogenous TNF is critical to maintain latent tuberculosis infection, and in its absence no specific immunity is generated.
Toll-Like Receptor 4-Mediated Innate IL-10 Activates Antigen-Specific Regulatory T Cells and Confers Resistance toBordetella pertussisby Inhibiting Inflammatory Pathology
Authors: Higgins Sarah C. , Lavelle Ed C. , McCann Chantelle , Keogh Brian , McNeela Edel , Byrne Patricia , O’Gorman Brian , Jarnicki Andrew , McGuirk Peter , Mills Kingston H. G. 
Published: April 2014

AbstractSignaling through Toll-like receptors (TLR) activates dendritic cell (DC) maturation and IL-12 production, which directs the induction of Th1 cells. We found that the production of IL-10, in addition to inflammatory cytokines and chemokines, was significantly reduced in DCs from TLR4-defective C3H/HeJ mice in response to Bordetella pertussis. TLR4 was also required for B. pertussis LPS-induced maturation of DCs, but other B. pertussis components stimulated DC maturation independently of TLR4. The course of B. pertussis infection was more severe in C3H/HeJ than in C3H/HeN mice. Surprisingly, Ab- and Ag-specific IFN-γ responses were enhanced at the peak of infection, whereas Ag-specific IL-10-producing T cells were significantly reduced in C3H/HeJ mice. This was associated with enhanced inflammatory cytokine production, cellular infiltration, and severe pathological changes in the lungs of TLR4-defective mice. Our findings suggest that TLR-4 signaling activates innate IL-10 production in response to B. pertussis, which both directly, and by promoting the induction of IL-10-secreting type 1 regulatory T cells, may inhibit Th1 responses and limit inflammatory pathology in the lungs during infection with B. pertussis.