bluuebunny/crossref_metadata_2025_split huggingface dataset:
Activating Immunity in the Liver. II. IFN-β Attenuates NK Cell-Dependent Liver Injury Triggered by Liver NKT Cell Activation
Authors: Trobonjaca Zlatko , Kröger Andrea , Stober Detlef , Leithäuser Frank , Möller Peter , Hauser Hansjörg , Schirmbeck Reinhold , Reimann Jörg 
Published: April 2014

AbstractDendritic cell (DC)-dependent activation of liver NKT cells triggered by a single i.v. injection of a low dose (10–100 ng/mouse) of α-galactosyl ceramide (αGalCer) into mice induces liver injury. This response is particularly evident in HBs-tg B6 mice that express a transgene-encoded hepatitis B surface Ag in the liver. Liver injury following αGalCer injection is suppressed in mice depleted of NK cells, indicating that NK cells play a role in NK T cell-initiated liver injury. In vitro, liver NKT cells provide a CD80/86-dependent signal to αGalCer-pulsed liver DC to release IL-12 p70 that stimulates the IFN-γ response of NKT and NK cells. Adoptive transfer of NKT cell-activated liver DC into the liver of nontreated, normal (immunocompetent), or immunodeficient (RAG−/− or HBs-tg/RAG−/−) hosts via the portal vein elicited IFN-γ responses of liver NK cells in situ. IFN-β down-regulates the pathogenic IL-12/IFN-γ cytokine cascade triggered by NKT cell/DC/NK cell interactions in the liver. Pretreating liver DC in vitro with IFN-β suppressed their IL-12 (but not IL-10) release in response to CD40 ligation or specific (αGalCer-dependent) interaction with liver NKT cells and down-regulated the IFN-γ response of the specifically activated liver NKT cells. In vivo, IFN-β attenuated the NKT cell-triggered induction of liver immunopathology. This study identifies interacting subsets of the hepatic innate immune system (and cytokines that up- and down-regulate these interactions) activated early in immune-mediated liver pathology.
Temporal Segregation of 4-1BB Versus CD28-Mediated Costimulation: 4-1BB Ligand Influences T Cell Numbers Late in the Primary Response and Regulates the Size of the T Cell Memory Response Following Influenza Infection
Authors: Bertram Edward M. , Lau Peggy , Watts Tania H. 
Published: April 2014

AbstractIn this report, we demonstrate that CD28−/− mice are severely impaired in the initial expansion of Db/NP366-374-specific CD8 T cells in response to influenza virus infection, whereas 4-1BB ligand (4-1BBL)−/− mice show no defect in primary T cell expansion to influenza virus. In contrast, 4-1BBL−/− mice show a decrease in Db/NP366-374-specific T cells late in the primary response. Upon secondary challenge with influenza virus, 4-1BBL−/− mice show a decrease in the number of Db/NP366-374-specific T cells compared to wild-type mice such that the level of the CD8 T cell expansion during the in vivo secondary response is reduced to the level of a primary response, with concomitant reduction of CTL effector function. In contrast, Ab responses, as well as secondary CD4 T cell responses, to influenza are unaffected by 4-1BBL deficiency. Thus, CD28 is critical for initial T cell expansion, whereas 4-1BB/4-1BBL signaling affects T cell numbers much later in the response and is essential for the survival and/or responsiveness of the memory CD8 T cell pool.
Continuous Exposure of Mice to Superantigenic Toxins Induces a High-Level Protracted Expansion and an Immunological Memory in the Toxin-Reactive CD4+ T Cells
Authors: Chen Luqiu , Koyanagi Madoka , Fukada Kenji , Imanishi Ken’ichi , Yagi Junji , Kato Hidehito , Miyoshi-Akiyama Tohru , Zhang Ruihua , Miwa Keishi , Uchiyama Takehiko 
Published: April 2014

AbstractWe analyzed the responses of several T cell fractions reactive with superantigenic toxins (SAGTs), staphylococcal enterotoxin A (SEA), or Yersinia pseudotuberculosis-derived mitogen (YPM) in mice implanted with mini-osmotic pumps filled with SEA or YPM. In mice implanted with the SEA pump, SEA-reactive Vβ3+CD4+ T cells exhibited a high-level protracted expansion for 30 days, and SEA-reactive Vβ11+CD4+ T cells exhibited a low-level protracted expansion. SEA-reactive CD8+ counterparts exhibited only a transient expansion. A similar difference in T cell expansion was also observed in YPM-reactive T cell fractions in mice implanted with the YPM pump. Vβ3+CD4+ and Vβ11+CD4+ T cells from mice implanted with the SEA pump exhibited cell divisions upon in vitro restimulation with SEA and expressed surface phenotypes as memory T cells. CD4+ T cells from mice implanted with the SEA pump exhibited high IL-4 production upon in vitro restimulation with SEA, which was due to the enhanced capacity of the SEA-reactive CD4+ T cells to produce IL-4. The findings in the present study indicate that, in mice implanted with a specific SAGT, the level of expansion of the SAGT-reactive CD4+ T cell fractions varies widely depending on the TCR Vβ elements expressed and that the reactive CD4+ T cells acquire a capacity to raise a memory response. CD8+ T cells are low responders to SAGTs.
The State of CD4+ T Cell Activation Is a Major Factor for Determining the Kinetics and Location of T Cell Responses to Oral Antigen
Authors: Lee Hae-ock , Cooper Cristine J. , Choi Jung-hee , Alnadjim Ziad , Barrett Terrence A. 
Published: April 2014

AbstractCurrent models suggest that inductive immune responses to enteric Ag are initiated in Peyer’s patches (PP) and mesenteric lymph nodes (MLN) followed by migration of activated, memory-like CD4+ T cells to extralymphoid sites in the intestinal lamina propria (LP). The resultant immune system contains both naive and activated T cells. To examine the differential responses of naive and memory-like T cells to oral Ag, bone marrow chimeras (BMC) were generated. Irradiated BALB/c hosts were reconstituted with a mix of DO11.10 × RAG-1−/− and BALB/c bone marrow. In unprimed DO11.10 and BMC models, LP and PP DO11.10 T cells responded to oral Ag with similar kinetics. Responses of activated, memory-like T cells to oral Ag were examined in thymectomized BMC 60 days after i.p. immunization with OVA peptide in Freund’s adjuvant (OVA323–339/CFA). Results indicate that i.p. OVA323–339/CFA generated a high proportion of memory-like CD45RBlow DO11.10 T cells in peripheral lymphoid (40%) and intestinal LP (70%) tissue. Previously activated DO11.10 T cells in the LP responded to oral Ag earlier and at 50% higher levels compared with memory CD4+ T cells localized to PP tissue. These data indicate that responses to oral Ag in antigenically naive animals are initiated in PP whereas in Ag-experienced animals LP T cells respond earlier and more vigorously than cells in PP. Taken together, these data suggest that previous activation alters the hierarchy of T cell responses to oral Ag by enhancing the efficiency of LP T cell activation.
Formation of the Killer Ig-Like Receptor Repertoire on CD4+CD28null T Cells
Authors: Snyder Melissa R. , Muegge Lars-Olof , Offord Chetan , O’Fallon William M. , Bajzer Zeljko , Weyand Cornelia M. , Goronzy Jörg J. 
Published: April 2014

Abstract
Killer Ig-like receptors (KIRs) are expressed on CD4+CD28null T cells, a highly oligoclonal subset of T cells that is expanded in patients with rheumatoid arthritis. It is unclear at what stage of development these T cells acquire KIR expression. To determine whether KIR expression is a consequence of clonal expansion and replicative senescence, multiple CD4+CD28null T cell clones expressing the in vivo dominant TCR β-chain sequences were identified in three patients and analyzed for their KIR gene expression pattern. Based on sharing of TCR sequences, the clones were grouped into five clone families. The repertoire of KIRs was diverse, even within each clone family; however, the gene expression was not random. Three particular receptors, KIR2DS2, KIR2DL2, and KIR3DL2, had significant differences in gene expression frequencies between the clone families. These data suggest that KIRs are successively acquired after TCR rearrangement, with each clone family developing a dominant expression pattern. The patterns did not segregate with the individual from whom the clones were derived, indicating that peripheral selection in the host environment was not a major shaping force. Several models were examined using a computer algorithm that was designed to simulate the expression of KIRs at various times during T cell proliferation. The computer simulations favored a model in which KIR gene expression is inducible for a limited time during the initial stages of clonal expansion.
Differential Roles for Extracellularly Regulated Kinase-Mitogen-Activated Protein Kinase in B Cell Antigen Receptor-Induced Apoptosis and CD40-Mediated Rescue of WEHI-231 Immature B Cells
Authors: Gauld Stephen B. , Blair Derek , Moss Catriona A. , Reid Steven D. , Harnett Margaret M. 
Published: April 2014

AbstractOne of the major unresolved questions in B cell biology is how the B cell Ag receptor (BCR) differentially signals to transduce anergy, apoptosis, proliferation, or differentiation during B cell maturation. We now report that extracellularly regulated kinase-mitogen-activated protein kinase (Erk-MAP kinase) can play dual roles in the regulation of the cell fate of the immature B cell lymphoma, WEHI-231, depending on the kinetics and context of Erk-MAP kinase activation. First, we show that the BCR couples to an early (≤2 h) Erk-MAP kinase signal which activates a phospholipase A2 pathway that we have previously shown to mediate collapse of mitochondrial membrane potential, resulting in depletion of cellular ATP and cathepsin B execution of apoptosis. Rescue of BCR-driven apoptosis by CD40 signaling desensitizes such early extracellularly regulated kinase (Erk) signaling and hence uncouples the BCR from the apoptotic mitochondrial phospholipase A2 pathway. A second role for Erk-MAP kinase in promoting the growth and proliferation of WEHI-231 immature B cells is evidenced by data showing that proliferating and CD40-stimulated WEHI-231 B cells exhibit a sustained cycling pattern (8–48 h) of Erk activation that correlates with cell growth and proliferation. This growth-promoting role for Erk signaling is supported by three key pieces of evidence: 1) signaling via the BCR, under conditions that induce growth arrest, completely abrogates sustained Erk activation; 2) CD40-mediated rescue from growth arrest correlates with restoration of cycling Erk activation; and 3) sustained inhibition of Erk prevents CD40-mediated rescue of BCR-driven growth arrest of WEHI-231 immature B cells. Erk-MAP kinase can therefore induce diverse biological responses in WEHI-231 cells depending on the context and kinetics of activation.
Negligible Class II MHC Presentation of B Cell Receptor-Derived Peptides by High Density Resting B Cells
Authors: Snyder Christopher M. , Zhang Xianghua , Wysocki Lawrence J. 
Published: April 2014

AbstractResting B lymphocytes have been credited with inducing T cell tolerance to Ig-derived and monovalent self-Ags that are internalized via the B cell receptor (BCR). These conclusions are predicated upon the assumptions that resting B cells display BCR-associated peptides in class II MHC and that the cells remain quiescent during the course of experimental manipulation. To determine whether resting B cells display BCR-associated epitopes in class II MHC, we devised a sensitive assay that averted potential activation of B cells by Ag and minimized activation by prolonged culture. Ex vivo, Percoll-fractionated B cells expressing a κ transgene encoding a T cell epitope were cultured with a reactive T cell hybridoma for 12 h. Whereas low density, LPS-activated, and BCR-activated B cells elicited significant IL-2 from the T cell hybridoma, resting high density B cells did not. Parallel results were obtained with normal B cells expressing a second epitope encoded by an endogenous VH gene. Anergic B cells, which are uniformly low density, also significantly stimulated the T cell hybridoma. Finally, longer culture periods with normal B cells resulted in a higher degree of B cell activation and significant stimulation of reactive T cell hybridomas. Our results provide evidence that activation of B cells profoundly enhances the processing and presentation of BCR-associated Ags.
The Complementarity-Determining Region-Like Loops of CD8α Interact Differently with β2-Microglobulin of the Class I Molecules H-2Kb and Thymic Leukemia Antigen, While Similarly with Their α3 Domains
Authors: Devine Lesley , Rogozinski Linda , Naidenko Olga V. , Cheroutre Hilde , Kavathas Paula B. 
Published: April 2014

Abstract
The murine CD8 glycoprotein interacts with both classical MHC class I molecules and some nonclassical molecules, including the thymic leukemia Ag (TL). TL binds preferentially to CD8αα homodimers with a 10-fold higher affinity than H-2Kb class I molecules. To understand the molecular basis for this difference, we created a panel of CD8α mutants and tested the ability of the CD8αα homodimers to bind to H-2Kb tetramers and TL tetramers. Mutations in three CD8 residues located on the complementarity-determining region-like loops contacting the negatively charged loop in the α3 domain of MHC class I greatly reduced binding to both tetramers. Because TL and H-2Kb class I sequences are highly conserved in the α3 domain of MHC class I, this suggests that CD8 contacts the α3 domain of TL and H-2Kb in a similar manner. In contrast, mutations in residues on the A and B β strands of CD8 that are involved in contact with β2-microglobulin affected interaction with the H-2Kb tetramer, but not the TL tetramer. Therefore, the orientation of interaction of TL with CD8 appears to be different from that of H-2Kb. The unique high affinity binding of TL with CD8αα is most likely a result of amino acid differences in the α3 domain between TL and H-2Kb, particularly at positions 198 (K to D) and 228 (M to T), which are contact residues in the CD8αα-H-2Kb cocrystal.
Complementarity-Determining Region 1 Sequence Requirements Drive Limited Vα Usage in Response to Influenza Hemagglutinin 307–319 Peptide
Authors: Brawley James V. , Concannon Patrick 
Published: April 2014

AbstractWe have developed a T cell activation-based system that allows for the selection of TCRs with defined peptide/MHC specificities from libraries in which complementarity-determining region (CDR) sequences have been randomized by in vitro mutagenesis. Using this system, we have explored the sequence requirements for CDR1 and CDR2 of the TCR α-chain in a human T cell response characterized by restricted Vα and Vβ usage. Libraries of T cells expressing receptors built on the framework of a TCR specific for the influenza virus peptide hemagglutinin 307–319 presented by HLA-DR4, but with random sequences inserted at CDR1α or CDR2α, were selected for response to the same peptide/MHC ligand. A wide variety of CDR2α sequences were found to be permissive for recognition. Indeed, &gt;25% of T cell clones chosen at random displayed a significant response. In contrast, a similar challenge of a randomized CDR1α library yielded only the parental sequence, and then only after multiple rounds of selection. T cell clones cross-reactive on closely related HLA alleles (subtypes of DR4) could be isolated from randomized libraries, but not clones restricted by more distantly related alleles such as HLA-DR1. These results indicate that, in the context of this T cell response, the structural requirements for recognition at CDR1α are significantly more restricted than at CDR2α. This system for mutation and selection of TCRs in vitro may be of use in engineering T cells with defined specificities for therapeutic applications.
Mitochondria-Dependent Caspase-9 Activation Is Necessary for Antigen Receptor-Mediated Effector Caspase Activation and Apoptosis in WEHI 231 Lymphoma Cells
Authors: Herold Marco J. , Kuss Andreas W. , Kraus Christa , Berberich Ingolf 
Published: April 2014

AbstractEngagement of the B cell Ag receptor (BCR) on immature B cells leads to growth arrest followed by apoptosis. Concomitant signaling through CD40 sustains proliferation and rescues the cells from apoptosis. Previously, we have shown that cross-linking CD40 on B cells stimulates the expression of A1, an antiapoptotic member of the Bcl-2 family, and that transduction of the murine B lymphoma line WEHI 231, a model for immature B cells, with A1 protected the cells against BCR-induced apoptosis. Here we demonstrate that A1 strongly interferes with activation of caspase-7, the major effector caspase activated after BCR cross-linking on WEHI 231 lymphoma cells. The pathway leading to activation of the effector caspase cascade including caspase-7 is unclear. Using retrovirally transduced WEHI 231 cell populations, we show that a catalytically inactive mutant of caspase-7 is cleaved almost as efficiently as the wild-type form, arguing against autocatalysis as the sole activating process. In contrast, overexpression of catalytically inactive caspase-9 strongly interferes with caspase-7 processing, poly(ADP-ribose) polymerase cleavage, and DNA laddering, suggesting a role for caspase-9 and hence for the mitochondrial pathway. The importance of the mitochondrial/caspase-9 pathway for BCR-triggered apoptosis is highlighted by our finding that both A1 and the mutant caspase-9 attenuate BCR-induced apoptosis. Thus, our data suggest that the BCR-mediated apoptotic signal in immature B cells spreads via a mitochondrial/caspase-9 pathway.
Regulation of IL-1 Receptor-Associated Kinases by Lipopolysaccharide
Authors: Hu Jean , Jacinto Randy , McCall Charles , Li Liwu 
Published: April 2014

Abstract
IL-1R-associated kinase (IRAK) plays a pivotal role in IL-1R/Toll-like receptor (TLR)-mediated signaling and NF-κB activation. IRAK from leukocytes undergoes rapid activation and inactivation/degradation following IL-1 or LPS stimulation. The rapid degradation of IRAK may serve as a negative feedback mechanism of down-regulating IL-1R/TLR-mediated signaling and cytokine gene transcription. Although IL-1/IL-1R-triggered IRAK degradation has been studied in detail, the mechanism of LPS-induced IRAK activation and degradation is not clearly defined. In this study, we demonstrate that the IRAK N-terminal 186-aa region is required for LPS-induced degradation. The N-terminally truncated IRAK protein expressed in human monocytic THP-1 cells remains stable upon LPS challenge. In comparison, IRAK as well as the IRAK mutant with C-terminal truncation undergo degradation with LPS stimulation. We demonstrate that pretreatment with protein kinase C inhibitor calphostin inhibits LPS-induced IRAK degradation. Furthermore, we observe coimmunoprecipitation of endogenous IRAK and protein kinase C-ζ protein. We show that functional TLR4 is required for LPS-mediated IRAK degradation. IRAK protein in the murine GG2EE cells harboring a mutated TLR4 gene does not undergo degradation upon LPS treatment. In sharp contrast, we observe that the IRAK homolog, IRAK2, does not undergo degradation upon prolonged LPS treatment, suggesting complex regulation of the innate immunity network upon microbial challenge.
An Analysis of T Cell Intrinsic Roles ofE2Aby Conditional Gene Disruption in the Thymus
Authors: Pan Lihua , Hanrahan Jenifer , Li Jie , Hale Laura P. , Zhuang Yuan 
Published: April 2014

AbstractThe importance of E2A transcription factors in T cell development has been demonstrated in studies of E2A-deficient mice, which display abnormal T cell development and a high frequency of T cell lymphomas. Because E2A expression is not restricted to the T cell lineage, the primary cause of the T cell phenotype in E2A-deficient mice was not fully determined. To further investigate the role of E2A in T cell lineage, we generated mice with the E2A gene disrupted exclusively during thymocyte development using the Cre-lox system. We show that this system allows E2A gene disruption to occur throughout the double-negative stage of thymocyte development. E2A deletion appears to be completed before development reaches the double-positive stage. Consistent with the gene disruption, these mice reveal a T cell intrinsic role for E2A during the transition from the double-negative stage to the double-positive stage of thymocyte development. In contrast to germline E2A knockout mice, conditional E2A knockout mice do not develop T cell lymphoma. This work establishes a new model for further investigating E2A function in T cell development and leukemiogenesis.
Fine Specificity of TCR Complementarity-Determining Region Residues and Lipid Antigen Hydrophilic Moieties in the Recognition of a CD1-Lipid Complex
Authors: Grant Ethan P. , Beckman Evan M. , Behar Samuel M. , Degano Massimo , Frederique Daphney , Besra Gurdyal S. , Wilson Ian A. , Porcelli Steven A. , Furlong Stephen T. , Brenner Michael B. 
Published: April 2014

Abstract
αβ TCR can recognize peptides presented by MHC molecules or lipids and glycolipids presented by CD1 proteins. Whereas the structural basis for peptide/MHC recognition is now clearly understood, it is not known how the TCR can interact with such disparate molecules as lipids. Recently, we demonstrated that the αβ TCR confers specificity for both the lipid Ag and CD1 isoform restriction, indicating that the TCR is likely to recognize a lipid/CD1 complex. We hypothesized that lipids may bind to CD1 via their hydrophobic alkyl and acyl chains, exposing the hydrophilic sugar, phosphate, and other polar functions for interaction with the TCR complementarity-determining regions (CDRs). To test this model, we mutated the residues in the CDR3 region of the DN1 TCR β-chain that were predicted to project between the CD1b α helixes in a model of the TCR/CD1 complex. In addition, we tested the requirement for the negatively charged and polar functions of mycolic acid for Ag recognition. Our findings indicate that the CDR loops of the TCR form the Ag recognition domain of CD1-restricted TCRs and suggest that the hydrophilic domains of a lipid Ag can form a combinatorial epitope recognized by the TCR.
Generation of Cytotoxic T Cells Against Virus-Infected Human Brain Macrophages in a Murine Model of HIV-1 Encephalitis
Authors: Poluektova Larisa Y. , Munn David H. , Persidsky Yuri , Gendelman Howard E. 
Published: April 2014

AbstractHIV-1 encephalitis (HIVE) and its associated dementia can occur in up to 20% of infected individuals, usually when productive viral replication in brain mononuclear phagocytes (macrophages and microglia) and depletion of CD4+ T lymphocytes are most significant. T cells control viral replication through much of HIV-1 disease, but how this occurs remains incompletely understood. With this in mind, we studied HIV-1-specific CTL responses in a nonobese diabetic (NOD)-SCID mouse model of HIVE. HIV-1-infected monocyte-derived macrophages (MDM) were injected into the basal ganglia after syngeneic immune reconstitution by HLA-A*0201-positive human PBL to generate a human PBL-NOD-SCID HIVE mouse. Engrafted T lymphocytes produced HIV-1gag- and HIV-1pol-specific CTL against virus-infected brain MDM within 7 days. This was demonstrated by tetramer staining of human PBL in mouse spleens and by IFN-γ ELISPOT. CD8, granzyme B, HLA-DR, and CD45R0 Ag-reactive T cells and CD79α-positive B cells migrated to and were in contact with human MDM in brain areas where infected macrophages were abundant. The numbers of productively infected MDM were markedly reduced (&gt;85%) during 2 wk of observation. The human PBL-NOD-SCID HIVE mouse provides a new tool for studies of cellular immune responses against HIV-1-infected brain mononuclear phagocytes during natural disease and after vaccination.