bluuebunny/crossref_metadata_2025_split huggingface dataset:
IL-12 Prevents the Inhibitory Effects of cis-Urocanic Acid on Tumor Antigen Presentation by Langerhans Cells: Implications for Photocarcinogenesis
Authors: Beissert Stefan , Rühlemann David , Mohammad Taj , Grabbe Stephan , El-Ghorr Ali , Norval Mary , Morrison Harry , Granstein Richard D. , Schwarz Thomas 
Published: April 2014

Abstract
UV radiation induces skin cancer primarily by its DNA-damaging properties, but also by its capacity to suppress the immune system. The photoisomer of urocanic acid (UCA), cis-UCA, is an important mediator of UV-induced immunosuppression and is involved in the inhibition of tumor immunity. The immunomodulatory cytokine IL-12 is known to counteract many of the immunosuppressive effects of UV radiation, including UV-induced immune tolerance. In this study, we addressed whether IL-12 also reverts the immunosuppressive activities of cis-UCA. Cis-UCA inhibits the ability of Langerhans cells to present tumor Ags for primary and secondary tumor immune responses. IL-12 treatment completely prevented the suppression by cis-UCA. IL-12 also protected mice from cis-UCA-induced suppression of contact hypersensitivity responses. To study the effects of cis-UCA on Ag-processing and Ag-presenting function in vitro, Langerhans cells were treated with UCA isomers and incubated with OVA or OVA peptide323–339 before exposure to OVA-specific transgenic T cells. Cis-, but not trans-UCA suppressed Ag presentation, which was completely reversed upon addition of IL-12. Since these findings suggest that cis-UCA may play an important role in photocarcinogenesis by inhibiting a tumor immune response, mice were chronically UVB irradiated to induce skin cancer. Whereas all mice in the control groups developed tumors, mice treated with a mAb with specificity for cis-UCA showed a significantly reduced tumor incidence. These data strongly indicate the importance of cis-UCA during photocarcinogenesis and support the concept of counteracting cis-UCA as an alternative strategy to prevent UV-induced skin cancer, possibly via the application of IL-12.
Lipopolysaccharide Modulation of Dendritic Cells Is Insufficient to Mature Dendritic Cells to Generate CTLs from Naive Polyclonal CD8+ T Cells In Vitro, Whereas CD40 Ligation Is Essential
Authors: Kelleher Michelle , Beverley Peter C. L. 
Published: April 2014

Abstract
Many cytotoxic CD8+ T cell responses are dependent on the interactions between CD40 ligand on the helper CD4+ T cell and CD40 on the APC. Although CD40 triggering of dendritic cells (DC) has been shown to mature the DC by increasing the level of expression of costimulatory molecules and inducing IL-12 secretion, the precise mechanisms by which CD40-CD40 ligand interactions allow DC to drive CTL responses remain unknown. We have used an in vitro model in which naive polyclonal CD8+ T cells can be activated by bone marrow-derived DC to investigate factor(s) that are responsible for this CD40-dependent generation of CTLs. DC modulated with agonistic anti-CD40 mAb (aCD40) are able to generate Ag-specific CTL responses while DC modulated with the microbial stimulus LPS alone do not. We compared the Ag-presenting capacity, levels of costimulatory molecules, and release of cytokines and chemokines of DC modulated with aCD40 to that of DC modulated by LPS. None of the factors assayed account for the unique capacity of anti-CD40-matured DC to drive CTL but this model provides a simplified system for further investigation. Although we attempted to use an LPS-free system for these studies, we are unable to rule out the possibility that very low levels of endotoxin (&lt;20 pg/ml) may synergize with CD40 ligation in the generation of CTLs.
Cre Recombinase-Mediated Inactivation of H-2Dd Transgene Expression: Evidence for Partial Missing Self-Recognition by Ly49A NK Cells
Authors: Ioannidis Vassilios , Zimmer Jacques , Beermann Friedrich , Held Werner 
Published: April 2014

Abstract
We have established H-2Dd-transgenic (Tg) mice, in which H-2Dd expression can be extinguished by Cre recombinase-mediated deletion of an essential portion of the transgene (Tg). NK cells adapted to the expression of the H-2Dd Tg in H-2b mice and acquired reactivity to cells lacking H-2Dd, both in vivo and in vitro. H-2Dd-Tg mice crossed to mice harboring an Mx-Cre Tg resulted in mosaic H-2Dd expression. That abrogated NK cell reactivity to cells lacking Dd. In Dd single Tg mice it is the Ly49A+ NK cell subset that reacts to cells lacking Dd, because the inhibitory Ly49A receptor is no longer engaged by its Dd ligand. In contrast, Ly49A+ NK cells from Dd × MxCre double Tg mice were unable to react to Dd-negative cells. These Ly49A+ NK cells retained reactivity to target cells that were completely devoid of MHC class I molecules, suggesting that they were not anergic. Variegated Dd expression thus impacts specifically missing Dd but not globally missing class I reactivity by Ly49A+ NK cells. We propose that the absence of Dd from some host cells results in the acquisition of only partial missing self-reactivity.
Requirement for Ca2+/Calmodulin-Dependent Kinase Type IV/Gr in Setting the Thymocyte Selection Threshold
Authors: Raman Vidya , Blaeser Frank , Ho Nga , Engle Deborah L. , Williams Calvin B. , Chatila Talal A. 
Published: April 2014

AbstractThe outcome of thymocyte selection is influenced by the nature of Ca2+ signals transduced by the TCR. Robust Ca2+ responses characterize high-affinity, negatively selecting peptide/TCR interactions, while modest responses typify lower-affinity, positively selecting interactions. To elucidate mechanisms by which thymocytes decode distinct Ca2+ signals, we examined selection events in mice lacking Ca2+/calmodulin-dependent protein kinase type IV/Gr (CaMKIV/Gr), which is enriched in thymocytes. CaMKIV/Gr-deficient thymocytes exhibited impaired positive selection and defective Ca2+-dependent gene transcription. Significantly, CaMKIV/Gr deficiency raised the selection threshold of peptide/TCR interactions such that a peptide that normally induced weak negative selection instead promoted positive selection. These results demonstrate an important role for CaMKIV/Gr in sensitizing thymocytes to selection by low-affinity peptides.
Without CD4 Help, CD8 Rejection of Pig Xenografts Requires CD28 Costimulation But Not Perforin Killing
Authors: Zhan Yifan , Brady Jamie L. , Sutherland Robyn M. , Lew Andrew M. 
Published: April 2014

AbstractAlthough CD4 cells are major mediators in cellular rejection of fetal pig pancreas (FPP) in the mouse, rejection still occurs in the absence of CD4 cells, albeit with delayed kinetics. CD4 cell-independent mechanisms of cellular rejection are poorly understood. To investigate the involvement of CD8 T cells in FPP rejection and their activation requirements, we used mice transgenic for anti-CD4 Ab; this is the most complete model of CD4 cell deficiency. We showed that in such mice FPP was infiltrated with CD8 cells starting from 2 wk posttransplantation and FPP was eventually rejected 8 wk posttransplantation. Ab depletion of CD8 cells greatly improved the survival of FPP and reduced cell infiltration at the graft site. This suggests that CD8 cells can mediate the rejection of porcine xenografts in the absence of CD4 cells. This CD8-mediated rejection of FPP is independent of their perforin-mediated lytic function, as graft survival was not affected in mice deficient in perforin. The production of IFN-γ and IL-5 by the graft infiltrates indicates that CD8 cells may act through cytokine-mediated mechanisms. Remarkably, in the absence of CD4 cells, lymphocyte infiltration at the graft site was absent in mice transgenic for CTLA4Ig such that the islet grafts flourished beyond 24 wk. In contrast, rejection was little affected by CD40 ligand deficiency. Therefore, we show that CD8 cells are activated to mediate FPP rejection independent of perforin and that this CD4-independent activation of CD8 cells critically depends on B7/CD28 costimulation.
Kinetics of Antigen-Induced Phenotypic and Functional Maturation of Human Monocyte-Derived Dendritic Cells
Authors: Hsieh Szu-Min , Pan Sung-Ching , Hung Chien-Ching , Tsai Hsing-Chun , Chen Mao-Yuan , Lee Chun-Nan , Chang Shan-Chwen 
Published: April 2014

Abstract
Dendritic cells (DCs), a critical component of innate immunity, are the most potent APCs. When DCs mature, they can elicit strong T cell responses. We studied the kinetics of Ag-induced phenotypic and functional maturation of human monocyte-derived DCs using an in vitro T cell-independent culture system. With this model, we herein show that an Ag that has recently or repetitively been exposed (“exposed Ag”) rapidly induces a high level of maturation; however, an Ag that has never or only remotely been exposed (“unexposed Ag”) slowly induces a low level of maturation. The kinetics of Ag-induced maturation of DCs possibly implies a novel mechanism for immunological memory that would provide maximal host protection from repetitively invading pathogens in the environment.
Constitutive Expression of LIGHT on T Cells Leads to Lymphocyte Activation, Inflammation, and Tissue Destruction
Authors: Shaikh Raziya B. , Santee Sybil , Granger Steven W. , Butrovich Kristine , Cheung Tim , Kronenberg Mitchell , Cheroutre Hilde , Ware Carl F. 
Published: April 2014

Abstract
LIGHT, a member of the TNF family of cytokines (homologous to lymphotoxin, exhibits inducible expression and competes with HSV glycoprotein D for herpesvirus entry mediator, a receptor expressed on T cells), is induced on activated T cells and mediates costimulatory and antitumor activity in vitro. Relatively little information is available on the in vivo effects of LIGHT expression, particularly within the T cell compartment. In this work, we describe transgenic mice that express human LIGHT under the control of the CD2 promoter, resulting in constitutive transgene expression in cells of the T lymphocyte lineage. LIGHT-transgenic animals exhibit abnormalities in both lymphoid tissue architecture and the distribution of lymphocyte subsets. They also show signs of inflammation that are most severe in the intestine, along with tissue destruction of the reproductive organs. These LIGHT-mediated effects were recapitulated when immune-deficient mice were reconstituted with bone marrow from LIGHT-transgenic donor mice. T cells in the LIGHT-transgenic mice have an activated phenotype and mucosal T cells exhibit enhanced Th1 cytokine activity. The results indicate that LIGHT may function as an important regulator of T cell activation, and implicate LIGHT signaling pathways in inflammation focused on mucosal tissues.
Transduction of an IL-2 Gene into Human Melanoma-Reactive Lymphocytes Results in Their Continued Growth in the Absence of Exogenous IL-2 and Maintenance of Specific Antitumor Activity
Authors: Liu Ke , Rosenberg Steven A. 
Published: April 2014

Abstract
IL-2-dependent activated cells undergo apoptotic death when IL-2 is withdrawn either in vitro or after in vivo cell transfer. To attempt to sustain their survival after IL-2 withdrawal, melanoma-reactive human T lymphocytes were retrovirally transduced with an exogenous human IL-2 gene. Transduced PBMC and cloned CD8+ T cells produced IL-2 and maintained viability after IL-2 withdrawal. Upon restimulation, IL-2 transductants proliferated in the absence of exogenous IL-2 and could be actively grown, and their survival could be maintained without added IL-2 for over 8 wk. PBMCs similarly transduced with a control vector did not produce IL-2 and failed to proliferate in the absence of IL-2. A CD8+ T cell clone, when transduced with an IL-2 gene, manifested the same phenotypes as PBMCs in the absence of exogenous IL-2. Furthermore, an Ab reactive with the α-chain of IL-2R complex reduced the viability mediated by IL-2 secretion of the IL-2 transductants. Moreover, transduction of an IL-2 gene did not affect the high degree of recognition and specificity of transductants against melanoma targets. These tumor-reactive IL-2 transductants may be valuable for in vitro studies and for improved adoptive transfer therapies for patients with metastatic melanoma.
Immunoreceptor Tyrosine-Based Inhibitory Motif of the IL-4 Receptor Associates with SH2-Containing Phosphatases and Regulates IL-4-Induced Proliferation
Authors: Kashiwada Masaki , Giallourakis Cosmas C. , Pan Ping-Ying , Rothman Paul B. 
Published: April 2014

Abstract
Immunoreceptor tyrosine-based inhibitory motifs (ITIM) have been implicated in the negative modulation of immunoreceptor signaling pathways. The IL-4R α-chain (IL-4Rα) contains a putative ITIM in the carboxyl terminal. To determine the role of ITIM in the IL-4 signaling pathway, we ablated the ITIM of IL-4Rα by deletion and site-directed mutagenesis and stably expressed the wild-type (WT) and mutant hIL-4Rα in 32D/insulin receptor substrate-2 (IRS-2) cells. Strikingly, 32D/IRS-2 cells expressing mutant human (h)IL-4Rα were hyperproliferative in response to IL-4 compared with cells expressing WT hIL-4Rα. Enhanced tyrosine phosphorylation of Stat6, but not IRS-2, induced by hIL-4 was observed in cells expressing mutant Y713F. Using peptides corresponding to the ITIM of hIL-4Rα, we demonstrate that tyrosine-phosphorylated peptides, but not their nonphosphorylated counterparts, coprecipitate SH2-containing tyrosine phosphatase-1, SH2-containing tyrosine phosphatase-2, and SH2-containing inositol 5′-phosphatase. The in vivo association of SH2-containing inositol 5′-phosphatase with IL-4Rα was verified by coimmunoprecipitation with anti-IL-4Rα Abs. These results demonstrate a functional role for ITIM in the regulation of IL-4-induced proliferation.
SH2 Domain-Containing Inositol Polyphosphate 5′-Phosphatase Is the Main Mediator of the Inhibitory Action of the Mast Cell Function-Associated Antigen
Authors: Xu Rong , Abramson Jakub , Fridkin Mati , Pecht Israel 
Published: April 2014

Abstract
The mast cell function-associated Ag (MAFA) is a type II membrane glycoprotein originally found on the plasma membrane of rat mucosal-type mast cells (RBL-2H3 line). A C-type lectin domain and an immunoreceptor tyrosine-based inhibitory motif (ITIM) are located in the extracellular and intracellular domains of MAFA, respectively. MAFA clustering has previously been shown to suppress the secretory response of these cells to the FcεRI stimulus. Here we show that the tyrosine of the ITIM undergoes phosphorylation, on MAFA clustering, that is markedly enhanced on pervanadate treatment of the cells. Furthermore, the Src homology 3 domain of the protein tyrosine kinase Lyn binds directly to a peptide containing nonphosphorylated MAFA ITIM and PAAP motif. Results of both in vitro and in vivo experiments suggest that Lyn is probably responsible for this ITIM phosphorylation, which increases the Src homology domain 2 (SH2) affinity of Lyn for the peptide. In vitro measurements established that tyrosine-phosphorylated MAFA ITIM peptides also bind the SH2 domains of inositol 5′-phosphatase (SHIP) as well as protein tyrosine phosphatase-2. However, the former single domain is bound 8-fold stronger than both of the latter. Further support for the role of SHIP in the action of MAFA stems from in vivo experiments in which tyrosine-phosphorylated MAFA was found to bind primarily SHIP. In RBL-2H3 cells overexpressing wild-type SHIP, MAFA clustering causes markedly stronger inhibition of the secretory response than in control cells expressing normal SHIP levels or cells overexpressing either wild-type protein tyrosine phosphatase-2 or its dominant negative form. In contrast, on overexpression of the SH2 domain of SHIP, the inhibitory action of MAFA is essentially abolished. Taken together, these results suggest that SHIP is the primary enzyme responsible for mediating the inhibition by MAFA of RBL-2H3 cell response to the FcεRI stimulus.
Functional and Structural Similarity of Vγ9Vδ2 T Cells in Humans and Aotus Monkeys, a Primate Infection Model for Plasmodium falciparum Malaria
Authors: Daubenberger Claudia A. , Salomon Maxence , Vecino William , Hübner Beatrice , Troll Heike , Rodriques Raul , Patarroyo Manuel E. , Pluschke Gerd 
Published: April 2014

Abstract
γδ T cells are implicated to play crucial roles during early immune responses to pathogens. A subset of human γδ T cells carrying the Vγ9Vδ2 TCR recognize small, phosphorylated nonpeptidic Ags. However, the precise role of these cells and the ligands recognized in human immune responses against pathogens remains unclear because of the lack of suitable animal models. We have analyzed the reactivity of spleen cells of the New World monkey Aotus nancymaae against isopentenyl pyrophosphate (IPP), a phosphorylated microbial metabolite selectively activating Vγ9Vδ2 T cells. Spleen cells were stimulated by IPP and the expanding cell population expressed the Vγ9 TCR. TRGV-J and TRDV-D-J rearrangements expressed by IPP-stimulated cells of Aotus were analyzed by RT-PCR and DNA sequencing. The TRGV-J and TRDV-D-J rearrangements expressed by IPP-stimulated Aotus and human γδ T cells were similar with respect to 1) TCR gene segment usage, 2) a high degree of germline sequence homology of the TCR gene segments used, and 3) the diversity of the CDR3 regions. Phylogenetic analysis of human, Pan troglodytes, and A. nancymaae TRGV gene segments showed that the interspecies differences are smaller than the intraspecies differences with TRGV9 gene segments located on a distinct clade of the phylogenetic tree. The structural and functional conservation of Vγ9Vδ2 T cells in A. nancymaae and humans implicates a functionally important and evolutionary conserved mechanism of recognition of phosphorylated microbial metabolites.
IFN-αβ-Dependent, IFN-γ Secretion by Bone Marrow-Derived Macrophages Controls an Intracellular Bacterial Infection
Authors: Gigliotti Rothfuchs Antonio , Gigliotti Dulceaydee , Palmblad Karin , Andersson Ulf , Wigzell Hans , Rottenberg Martín E. 
Published: April 2014

Abstract
Several reports have indicated that cell lineages apart from NK and T cells can also express IFN-γ. However, the biological relevance of this finding is uncertain. We show in this study that bone marrow-derived macrophages (BMMs) express IFN-γ at the mRNA and protein level early after infection with Chlamydia pneumoniae. Increased IFN-γ mRNA accumulation by infected BMMs is early, transient, and requires both bacterial and host protein synthesis. The induction of IFN-γ mRNA levels is independent of IL-12 and was dramatically enhanced in IL-10−/− BMMs. Such IL-10−/− BMMs contained less bacteria than the wild-type controls, whereas IFN-γR−/− BMMs showed increased C. pneumoniae load. Inducible NO synthase (iNOS) also participates in the control of bacterial load, as shown by the enhanced numbers of C. pneumoniae in iNOS−/− BMMs. However, the increased accumulation of iNOS mRNA and NO in C. pneumoniae-infected BMMs depended on the presence of IFN-αβ, but was independent of IFN-γ. Interestingly, IFN-αβ are also required for increased IFN-γ mRNA accumulation in C. pneumoniae-infected BMMs. Accordingly, IFN-αβR−/− BMMs showed higher levels of C. pneumoniae than wild-type BMMs. Our findings unravel an autocrine/paracrine macrophage activation pathway by showing an IFN-αβ-dependent IFN-γ and iNOS induction in response to infection, which protects macrophages against intracellular bacterial growth.
Immunization with gp96 from Listeria monocytogenes-Infected Mice Is Due to N-Formylated Listerial Peptides
Authors: Sponaas Anne-Marit , Zuegel Ulrich , Weber Stephan , Hurwitz Robert , Winter Ralf , Lamer Stephanie , Jungblut Peter R. , Kaufmann Stefan H. E. 
Published: April 2014

Abstract
N-Formylated (N-f-met) peptides derived from proteins of the intracellular bacterium Listeria monocytogenes generate a protective, H2-M3-restricted CD8 T cell response in C57BL/6 mice. N-f-met peptide-specific CTL were generated in vitro when mice previously immunized with gp96 isolated from donor mice infected with L. monocytogenes were stimulated with these peptides. No significant peptide-specific CTL activity was observed in mice immunized with gp96 from uninfected animals. Masses corresponding to one N-f-met peptide were found by matrix-assisted laser desorption/ionization-mass spectrometry on gp96 isolated from C57BL/6 mice infected with L. monocytogenes, but not on gp96 from noninfected mice. Therefore, bacterial N-f-met peptides from intracellular bacteria can bind to gp96 in the infected host, and gp96 loaded with these peptides can generate N-f-met-peptide-specific CTL. We assume a unique role of gp96 in Ag processing through the H2-M3 pathway.
A Novel Mimetic Antigen Eliciting Protective Antibody toNeisseria meningitidis
Authors: Granoff Dan M. , Moe Gregory R. , Giuliani Marzia M. , Adu-Bobie Jeannette , Santini Laura , Brunelli Brunella , Piccinetti Francesca , Zuno-Mitchell Patricia , Lee Sharon S. , Neri Paolo , Bracci Luisa , Lozzi Luisa , Rappuoli Rino 
Published: April 2014

AbstractMolecular mimetic Ags are of considerable interest as vaccine candidates. Yet there are few examples of mimetic Ags that elicit protective Ab against a pathogen, and the functional activity of anti-mimetic Abs has not been studied in detail. As part of the Neisseria meningitidis serogroup B genome sequencing project, a large number of novel proteins were identified. Herein, we provide evidence that genome-derived Ag 33 (GNA33), a lipoprotein with homology to Escherichia coli murein transglycosylase, elicits protective Ab to meningococci as a result of mimicking an epitope on loop 4 of porin A (PorA) in strains with serosubtype P1.2. Epitope mapping of a bactericidal anti-GNA33 mAb using overlapping peptides shows that the mAb recognizes peptides from GNA33 and PorA that share a QTP sequence that is necessary but not sufficient for binding. By flow cytometry, mouse antisera prepared against rGNA33 and the anti-GNA33 mAb bind as well as an anti-PorA P1.2 mAb to the surface of eight of nine N. meningitidis serogroup B strains tested with the P1.2 serosubtype. Anti-GNA33 Abs also are bactericidal for most P1.2 strains and, for susceptible strains, the activity of an anti-GNA33 mAb is similar to that of an anticapsular mAb but less active than an anti-P1.2 mAb. Anti-GNA Abs also confer passive protection against bacteremia in infant rats challenged with P1.2 strains. Thus, GNA33 represents one of the most effective immunogenic mimetics yet described. These results demonstrate that molecular mimetics have potential as meningococcal vaccine candidates.
CXCR2 Deficiency Confers Impaired Neutrophil Recruitment and Increased Susceptibility DuringToxoplasma gondiiInfection
Authors: Del Rio Laura , Bennouna Soumaya , Salinas Jesus , Denkers Eric Y. 
Published: April 2014

AbstractNeutrophil migration to the site of infection is a critical early step in host immunity to microbial pathogens, in which chemokines and their receptors play an important role. In this work, mice deficient in expression of the chemokine receptor CXCR2 were infected with Toxoplasma gondii and the outcome was monitored. Gene-deleted animals displayed completely defective neutrophil recruitment, which was apparent at 4 h and sustained for at least 36 h. KitW/KitW-v animals also displayed defective polymorphonuclear leukocyte migration, suggesting mast cells as one source of chemokines driving the response. Tachyzoite infection and replication were accelerated in CXCR2−/− animals, resulting in establishment of higher cyst numbers in the brain relative to wild-type controls. Furthermore, serum and spleen cell IFN-γ levels in infected, gene-deleted mice were reduced 60–75% relative to infected normal animals, and spleen cell TNF-α was likewise reduced by ∼50%. These results highlight an important role for CXCR2 in neutrophil migration, which may be important for early control of infection and induction of immunity during Toxoplasma infection.