bluuebunny/crossref_metadata_2025_split huggingface dataset:
CD4+CD25+ Regulatory T Cells Attenuate the Phosphatidylinositol 3-Kinase/Akt Pathway in Antigen-Primed Immature CD8+ CTLs during Functional Maturation
Authors: Kojima Hidefumi , Kanno Yumiko , Hase Hidenori , Kobata Tetsuji 
Published: April 2014

AbstractThis study was designed to determine the role of CD25+CD4+ regulatory T (Tr) cells in CTL maturation and effector functions using a murine CTL line and in vitro MLC. Tr cells inhibited CTL functional maturation, but had no effect on CTL effector functions. In CD4+ responder T cell-depleted MLC supplemented with IL-2, Tr cells suppressed mature CTL generation only when added within the first 2 days of culture. Tr cells down-regulated levels of active Akt, but not STAT5 or ZAP70 in Ag-primed immature CTLs. Down-regulation of active Akt was accompanied by a reduction in CTL cell size and IL-2Rα expression. In Tr cell-depleted MLC, CTLs were generated that exhibited high levels of nonspecific cytotoxicity. Our in vitro findings suggest that Tr cells regulate functional CTL maturation to generate optimal Ag-specific immune responses through the control of the PI3K/Akt pathway.
Multiple Costimulatory Modalities Enhance CTL Avidity
Authors: Hodge James W. , Chakraborty Mala , Kudo-Saito Chie , Garnett Charlie T. , Schlom Jeffrey 
Published: April 2014

AbstractRecent studies in both animal models and clinical trials have demonstrated that the avidity of T cells is a major determinant of antitumor and antiviral immunity. In this study, we evaluated several different vaccine strategies for their ability to enhance both the quantity and avidity of CTL responses. CD8+ T cell quantity was measured by tetramer binding precursor frequency, and avidity was measured by both tetramer dissociation and quantitative cytolytic function. We have evaluated a peptide, a viral vector expressing the Ag transgene alone, with one costimulatory molecule (B7-1), and with three costimulatory molecules (B7-1, ICAM-1, and LFA-3), with anti-CTLA-4 mAb, with GM-CSF, and combinations of the above. We have evaluated these strategies in both a foreign Ag model using β-galactosidase as immunogen, and in a “self” Ag model, using carcinoembryonic Ag as immunogen in carcinoembryonic Ag transgenic mice. The combined use of several of these strategies was shown to enhance not only the quantity, but, to a greater magnitude, the avidity of T cells generated; a combination strategy is also shown to enhance antitumor effects. The results reported in this study thus demonstrate multiple strategies that can be used in both antitumor and antiviral vaccine settings to generate higher avidity host T cell responses.
IFN Regulatory Factor-2 Deficiency Revealed a Novel Checkpoint Critical for the Generation of Peripheral NK Cells
Authors: Taki Shinsuke , Nakajima Shinsuke , Ichikawa Eri , Saito Takashi , Hida Shigeaki 
Published: April 2014

Abstract
NK cell development is far less understood compared with that of T and B cells despite the critical importance of NK cells in innate immunity. Mice lacking the transcription factor IFN regulatory factor-2 (IRF-2) are known to exhibit NK cell deficiency. However, the role of IRF-2 in NK cell development has remained unclear. In this study we found that NK cell deficiency in the periphery in IRF-2-deficient mice was due to selective loss of mature NK cells, but not to maturation arrest, and NK cells in these mice exhibited very immature surface phenotypes (CD11blowDx5low) with highly compromised NK receptor expression. In contrast, IRF-2-deficient NK cells in bone marrow (BM) showed relatively mature phenotypes (CD11blowDx5high) with less compromised NK receptor repertoire. Furthermore, BM NK cells in IRF-2-deficient mice were found to proliferate almost normally, but underwent accelerated apoptosis. These observations indicated that NK cell maturation could advance up to a late, but not the final, stage in the BM, whereas these cells were incapable of contributing to the peripheral NK cell pool due to premature death in the absence of IRF-2. In contrast, NK cell numbers and Ly49 expression were much more severely reduced in BM in IL-15-deficient mice than in IRF-2−/− mice. The differential peripheral and central NK cell deficiencies in IRF-2−/− mice thus revealed a novel late checkpoint for NK cell maturation, distinct from the early IL-15-dependent expansion stage.
CD40 Ligation Activates Murine Macrophages via an IFN-γ-Dependent Mechanism Resulting in Tumor Cell Destruction In Vitro
Authors: Buhtoiarov Ilia N. , Lum Hillary , Berke Gideon , Paulnock Donna M. , Sondel Paul M. , Rakhmilevich Alexander L. 
Published: April 2014

AbstractWe have shown previously that agonistic anti-CD40 mAb induced T cell-independent antitumor effects in vivo. In this study, we investigated mechanisms of macrophage activation with anti-CD40 mAb treatment, assessed by the antitumor action of macrophages in vitro. Intraperitoneal injection of anti-CD40 mAb into C57BL/6 mice resulted in activation of peritoneal macrophages capable of suppressing B16 melanoma cell proliferation in vitro, an effect that was greatly enhanced by LPS and observed against several murine and human tumor cell lines. Anti-CD40 mAb also primed macrophages in vitro to mediate cytostatic effects in the presence of LPS. The tumoristatic effect of CD40 ligation-activated macrophages was associated with apoptosis and killing of tumor cells. Activation of macrophages by anti-CD40 mAb required endogenous IFN-γ because priming of macrophages by anti-CD40 mAb was abrogated in the presence of anti-IFN-γ mAb, as well as in IFN-γ-knockout mice. Macrophages obtained either from C57BL/6 mice depleted of T and NK cells by Ab treatment, or from scid/beige mice, were still activated by anti-CD40 mAb to mediate cytostatic activity. These results argued against the role of NK and T cells as the sole source of exogenous IFN-γ for macrophage activation and suggested that anti-CD40 mAb-activated macrophages could produce IFN-γ. We confirmed this hypothesis by detecting intracytoplasmic IFN-γ in macrophages activated with anti-CD40 mAb in vivo or in vitro. IFN-γ production by macrophages was dependent on IL-12. Taken together, the results show that murine macrophages are activated directly by anti-CD40 mAb to secrete IFN-γ and mediate tumor cell destruction.
Cyclophilin A-Deficient Mice Are Resistant to Immunosuppression by Cyclosporine
Authors: Colgan John , Asmal Mohammed , Yu Bin , Luban Jeremy 
Published: April 2014

AbstractCyclosporine is an immunosuppressive drug that is widely used to prevent organ transplant rejection. Known intracellular ligands for cyclosporine include the cyclophilins, a large family of phylogenetically conserved proteins that potentially regulate protein folding in cells. Immunosuppression by cyclosporine is thought to result from the formation of a drug-cyclophilin complex that binds to and inhibits calcineurin, a serine/threonine phosphatase that is activated by TCR engagement. Amino acids within the cyclophilins that are critical for binding to cyclosporine have been identified. Most of these residues are highly conserved within the 15 mammalian cyclophilins, suggesting that many are potential targets for the drug. We examined the effects of cyclosporine on immune cells and mice lacking Ppia, the gene encoding the prototypical cyclophilin protein cyclophilin A. TCR-induced proliferation and signal transduction by Ppia−/− CD4+ T cells were resistant to cyclosporine, an effect that was attributable to diminished calcineurin inhibition. Immunosuppressive doses of cyclosporine failed to block the responses of Ppia−/− mice to allogeneic challenge. Rag2−/− mice reconstituted with Ppia−/− splenocytes were also cyclosporine resistant, indicating that this property is intrinsic to Ppia−/− immune cells. Thus, among multiple potential ligands, CypA is the primary mediator of immunosuppression by cyclosporine.
Spontaneous and Homeostatic Proliferation of CD4 T Cells Are Regulated by Different Mechanisms
Authors: Min Booki , Yamane Hidehiro , Hu-Li Jane , Paul William E. 
Published: April 2014

Abstract
Transfer of naive CD4 T cells into lymphopenic mice initiates a proliferative response of the transferred cells, often referred to as homeostatic proliferation. Careful analysis reveals that some of the transferred cells proliferate rapidly and undergo robust differentiation to memory cells, a process we have designated spontaneous proliferation, and other cells proliferate relatively slowly and show more limited evidence of differentiation. In this study we report that spontaneous proliferation is IL-7 independent, whereas the slow proliferation (referred to as homeostatic proliferation) is IL-7 dependent. Administration of IL-7 induces homeostatic proliferation of naive CD4 T cells even within wild-type recipients. Moreover, the activation/differentiation pattern of the two responses are clearly distinguishable, indicating that different activation mechanisms may be involved. Our results reveal the complexity and heterogeneity of lymphopenia-driven T cell proliferation and suggest that they may have fundamentally distinct roles in the maintenance of CD4 T cell homeostasis.
Preferential Cell Death of CD8+ Effector Memory (CCR7−CD45RA−) T Cells by Hydrogen Peroxide-Induced Oxidative Stress
Authors: Takahashi Akihiro , Hanson Mikael G. V. , Norell Håkan R. , Havelka Aleksandra Mandic , Kono Koji , Malmberg Karl-Johan , Kiessling Rolf V. R. 
Published: April 2014

AbstractT cells are used in many cell-based cancer treatments. However, oxidative stress that is induced during various chronic inflammatory conditions, such as cancer, can impair the immune system and have detrimental effects on T cell function. In this study, we have investigated the sensitivity of different human T cell subsets to H2O2-induced oxidative stress. We showed that central memory (CD45RA−CCR7+) and effector memory (CD45RA−CCR7−) T cells are more sensitive to H2O2 as compared with naive (CD45RA+CCR7+) T cells. Furthermore, the study showed that CD8+ effector memory T cells are more sensitive to low levels of H2O2 (5 μM) compared with other types of T cells investigated. H2O2-exposed CD45RO+ T cells showed mitochondrial depolarization prior to caspase 3 activity. Moreover, the pan-caspase inhibitor z-Val-Ala-Asp(OMe)-fluoromethylketone rescued cells from death. These experiments suggest that H2O2-induced cell death of CD45RO+ T cells acts via the mitochondrial pathway and that caspase involvement is needed. This study suggests that oxidative stress in cancer patients can be disadvantageous for T cell-based adoptive cell transfer therapies, since effector memory T cells are the primary phenotype of the cells administered.
TGF-β Inhibits Fas-Mediated Apoptosis of a Follicular Dendritic Cell Line by Down-Regulating the Expression of Fas and Caspase-8: Counteracting Role of TGF-β on TNF Sensitization of Fas-Mediated Apoptosis
Authors: Park Sun-Mi , Kim Sunshin , Choi Jin-Suk , Hur Dae-Young , Lee Wang-Jae , Lee Myung-Shik , Choe Jongseon , Lee Tae H. 
Published: April 2014

Abstract
Follicular dendritic cells (FDC) constitute the framework of germinal center (GC) in secondary lymphoid follicles, and the integrity of FDC networks is critically affected by cytokines present in the GC. We have previously shown that TNF promotes Fas-mediated apoptosis of HK cells, an established FDC-like cell line, by up-regulating Fas expression. However, in the developing GC, FDC death is not a hallmark of GC despite the presence of TNF and FasL. In this study, we report that TGF-β inhibits Fas-mediated apoptosis of HK cells by down-regulating the expression of surface Fas and caspase-8. The inhibitory effect of TGF-β can be observed when HK cells were simultaneously treated with TNF and TGF-β, indicating that TGF-β counteracts the effect of TNF in sensitizing cells to Fas-mediated apoptosis. Furthermore, the deprivation of TGF-β by injecting neutralizing TGF-β Abs to the SRBC-immunized mice resulted in the sporadic appearance of FDC undergoing apoptosis in the lymphoid follicles, suggesting that TGF-β functions as a naturally occurring inhibitor that rescues FDCs which are predisposed to apoptosis. Our study documents a novel function of TGF-β in the maintenance of FDC networks.
Interallelic Class Switch Recombination Contributes Significantly to Class Switching in Mouse B Cells
Authors: Reynaud Stéphane , Delpy Laurent , Fleury Laurence , Dougier Hei-Lanne , Sirac Christophe , Cogné Michel 
Published: April 2014

AbstractExcept for the expression of IgM and IgD, DNA recombination is constantly needed for the expression of other Ig classes and subclasses. The predominant path of class switch recombination (CSR) is intrachromosomal, and the looping-out and deletion model has been abundantly documented. However, switch regions also occasionally constitute convenient substrates for interchromosomal recombination, since it is noticeably the case in a number of chromosomal translocations causing oncogene deregulation in the course of lymphoma and myeloma. Although asymmetric accessibility of Ig alleles should theoretically limit its occurrence, interallelic CSR was shown to occur at low levels during IgA switching in rabbit, where the definition of allotypes within both V and C regions helped identify interchromosomally derived Ig. Thus, we wished to evaluate precisely interallelic CSR frequency in mouse B cells, by using a system in which only one allele (of b allotype) could express a functional VDJ region, whereas only interallelic CSR could restore expression of an excluded (a allotype) allele. In our study, we show that interchromosomal recombination of VH and Cγ or Cα occurs in vivo in B cells at a frequency that makes a significant contribution to physiological class switching: trans-association of VH and CH genes accounted for 7% of all α mRNA, and this frequency was about twice higher for the γ3 transcripts, despite the much shorter distance between the JH region and the Cγ3 gene, thus confirming that this phenomenon corresponded to site-specific switching and not to random recombination between long homologous loci.
Demethylation of the Same Promoter Sequence Increases CD70 Expression in Lupus T Cells and T Cells Treated with Lupus-Inducing Drugs
Authors: Lu Qianjin , Wu Ailing , Richardson Bruce C. 
Published: April 2014

Abstract
Exposing genetically predisposed individuals to certain environmental agents is believed to cause human lupus. How environmental agents interact with the host to cause lupus is poorly understood. Procainamide and hydralazine are drugs that cause lupus in genetically predisposed individuals. Understanding how these environmental agents cause lupus may indicate mechanisms relevant to the idiopathic disease. Abnormal T cell DNA methylation, a repressive epigenetic DNA modification, is implicated in procainamide and hydralazine induced lupus, as well as idiopathic lupus. Procainamide is a competitive DNA methyltransferase (Dnmt) inhibitor, hydralazine inhibits ERK pathway signaling thereby decreasing Dnmt expression, and in lupus T cells decreased ERK pathway signaling causing a similar Dnmt decrease. T cells treated with procainamide, hydralazine, and other Dnmt and ERK pathway inhibitors cause lupus in mice. Whether the same genetic regulatory elements demethylate in T cells treated with Dnmt inhibitors, ERK pathway inhibitors, and in human lupus is unknown. CD70 (TNFSF7) is a B cell costimulatory molecule overexpressed on CD4+ lupus T cells as well as procainamide and hydralazine treated T cells, and contributes to excessive B cell stimulation in vitro and in lupus. In this report we identify a genetic element that suppresses CD70 expression when methylated, and which demethylates in lupus and in T cells treated with Dnmt and ERK pathway inhibitors including procainamide and hydralazine. The results support a model in which demethylation of specific genetic elements in T cells, caused by decreasing Dnmt expression or inhibiting its function, contributes to drug-induced and idiopathic lupus through altered gene expression.
Beyond the 12/23 Rule of VDJ Recombination Independent of the Rag Proteins
Authors: Olaru Alexandru , Petrie Howard T. , Livák Ferenc 
Published: April 2014

AbstractThe combinatorial repertoire of AgRs is established through somatic recombination of V, D, and J gene segments during lymphocyte development. Incorporation of D segments into IgH, TCRβ, and TCRδ chains also contributes to junctional diversification by substantially extending the length of the third CDR. The V, D, and J gene segments are flanked by recombination signals (RS) of 12- or 23-mer spacer length that direct recombination according to the 12/23 rule. D genes in the TCRβ and TCRδ loci are flanked by a 12RS and 23RS, and their incorporation is controlled by mechanisms “beyond the 12/23 rule.” In the TCRβ locus, selective interactions between Rag proteins and the RS flanking the V-D and D-J genes, respectively, are sufficient to enforce D gene usage. In this article, we report that in the TCRδ locus, the Rag proteins are not the major determinant of D gene incorporation. In developing mouse and human thymocytes, the two Dδ genes rearrange predominantly to form D-D coding joints. In contrast, when tested in ex vivo transfection assays in a nonlymphoid cell line, the flanking RS mediate deletion, rather than incorporation, of the two D genes on both exogenous recombination substrates and the endogenous locus. These results suggest that selective Rag-RS interactions are not the sole regulators of D gene segment incorporation, and additional, perhaps lymphocyte-specific, mechanisms exist that allow proper shaping of the primary AgR repertoire.
A New Tyrosine Phosphorylation Site in PLCγ1: The Role of Tyrosine 775 in Immune Receptor Signaling
Authors: Serrano Carmen J. , Graham Laurie , DeBell Karen , Rawat Rashmi , Veri Maria Concetta , Bonvini Ezio , Rellahan Barbara L. , Reischl Ilona G. 
Published: April 2014

Abstract
Phospholipase Cγ (PLCγ) is a ubiquitous gatekeeper of calcium mobilization and diacylglycerol-mediated events induced by the activation of Ag and growth factor receptors. The activity of PLCγ is regulated through its controlled membrane translocation and tyrosine (Y) phosphorylation. Four activation-induced tyrosine phosphorylation sites have been previously described (Y472, Y771, Y783, and Y1254), but their specific roles in Ag receptor-induced PLCγ1 activation are not fully elucidated. Unexpectedly, we found that the phosphorylation of a PLCγ1 construct with all four sites mutated to phenylalanine was comparable with that observed with wild-type PLCγ1, suggesting the existence of an unidentified site(s). Sequence alignment with known phosphorylation sites in PLCγ2 indicated homology of PLCγ1 tyrosine residue 775 (Y775) with PLCγ2 Y753, a characterized phosphorylation site. Tyrosine 775 was characterized as a phosphorylation site using phospho-specific anti-Y775 antiserum, and by mutational analysis. Phosphorylation of Y775 did not depend on the other tyrosines, and point mutation of PLCγ1 Y775, or the previously described Y783, substantially reduced AgR-induced calcium, NF-AT, and AP-1 activation. Mutation of Y472, Y771, and Y1254 had no effect on overall PLCγ1 phosphorylation or activation. Although the concomitant mutation of Y775 and Y783 abolished downstream PLCγ1 signaling, these two tyrosines were sufficient to reconstitute the wild-type response in the absence of functional Y472, Y771, and Y1254. These data establish Y775 as a critical phosphorylation site for PLCγ1 activation and confirm the functional importance of Y783.
Mouse Cathelin-Related Antimicrobial Peptide Chemoattracts Leukocytes Using Formyl Peptide Receptor-Like 1/Mouse Formyl Peptide Receptor-Like 2 as the Receptor and Acts as an Immune Adjuvant
Authors: Kurosaka Kahori , Chen Qian , Yarovinsky Felix , Oppenheim Joost J. , Yang De 
Published: April 2014

Abstract
Mammalian antimicrobial proteins, such as defensins and cathelicidin, have stimulating effects on host leukocytes. Cathelin-related antimicrobial peptide (CRAMP), the orthologue of human cathelicidin/LL-37, is the sole identified murine cathelicidin. CRAMP has been shown to have both antimicrobial and angiogenic activities. However, whether CRAMP, like human cathelicidin/LL-37, also exhibits a direct effect on the migration and function of leukocytes is not known. We have observed that CRAMP, like LL-37, was chemotactic for human monocytes, neutrophils, macrophages, and mouse peripheral blood leukocytes. CRAMP also induced calcium mobilization and the activation of MAPK in monocytes. CRAMP-induced calcium flux in monocytes was desensitized by MMK-1, an agonistic ligand specific for formyl peptide receptor-like-1 (FPRL1), and vice versa, suggesting the use of FPRL1 by CRAMP as a receptor. Furthermore, CRAMP induced the chemotaxis of human embryonic kidney 293 cells transfected with either FPRL1 or mouse formyl peptide receptor-2, the mouse homologue of FPRL1, but not by untransfected parental human embryonic kidney 293 cells, confirming the use of FPRL1/mouse formyl peptide receptor-2 by CRAMP. Injection of CRAMP into mouse air pouches resulted in the recruitment predominantly of neutrophils and monocytes, indicating that CRAMP acts as a chemotactic factor in vivo. Finally, simultaneous administration of OVA with CRAMP to mice promoted both humoral and cellular Ag-specific immune responses. Thus, CRAMP functions as both a chemoattractant for phagocytic leukocytes and an enhancer of adaptive immune response.
Protective Immunity to Genital Herpes Simpex Virus Type 2 Infection Is Mediated by T-bet
Authors: Svensson Alexandra , Nordström Inger , Sun Jia-Bin , Eriksson Kristina 
Published: April 2014

AbstractWe show, for the first time, that the transcription factor T-bet, which is implicated in IFN-γ production, is required for the induction of vaccine-induced antiviral immune protection. T-bet was found to be important in both the innate and acquired immune protection against genital HSV-2 infection. T-bet−/− and T-bet+/+ mice were infected vaginally with HSV-2 and examined daily for disease and mortality. T-bet−/− mice had significantly higher virus titers than T-bet+/+ mice following a primary HSV-2 infection, and succumbed significantly earlier to the infection. This result was associated with an impaired NK cell cytotoxic capacity and NK cell-mediated IFN-γ production in the T-bet−/− mice. To assess the induction of acquired antiviral immune protection, mice were vaccinated with an attenuated virus before infection. Vaccinated T-bet−/− mice could not control viral replication following an HSV-2 challenge and had significantly higher virus titers and mortality rates than vaccinated T-bet+/+ mice that remained healthy. The impaired acquired immune protection in T-bet−/− mice was associated with a significantly decreased HSV-2-specific delayed-type hypersensitivity response and a significantly reduced HSV-2-specific IFN-γ production from CD4+ T cells. However, T-bet deficiency did not impair either the IFN-γ production or the cytotoxic capacity of HSV-2-specific CD8+ T cells. We conclude that T-bet plays a crucial role in both the innate defense and the generation of vaccine-induced immunity against genital HSV-2 infection in mice.