bluuebunny/crossref_metadata_2025_split huggingface dataset:
Costimulation of Multiple NK Cell Activation Receptors by NKG2D
Authors: Ho Emily L. , Carayannopoulos Leonidas N. , Poursine-Laurent Jennifer , Kinder Jeremy , Plougastel Beatrice , Smith Hamish R. C. , Yokoyama Wayne M. 
Published: April 2014

AbstractThe activation of NK cells is mediated through specific interactions between activation receptors and their respective ligands. Little is known, however, about whether costimulation, which has been well characterized for T cell activation, occurs in NK cells. To study the function of NKG2D, a potential NK costimulatory receptor, we have generated two novel hamster mAbs that recognize mouse NKG2D. FACS analyses demonstrate that mouse NKG2D is expressed on all C57BL/6 IL-2-activated NK (lymphokine-activated killer (LAK)) cells, all splenic and liver NK cells, and ∼50% of splenic NKT cells. Consistent with limited polymorphism of NKG2D, its sequence is highly conserved, and the anti-NKG2D mAbs react with NK cells from a large number of different mouse strains. In chromium release assays, we show that stimulation of NK cells with anti-NKG2D mAb can redirect lysis. Also, enhanced lysis of transfected tumor targets expressing NKG2D ligand could be inhibited by addition of anti-NKG2D mAb. Interestingly, stimulation of LAK cells via NKG2D alone does not lead to cytokine release. However, stimulation of LAK via both an NK activation receptor (e.g., CD16, NK1.1, or Ly-49D) and NKG2D leads to augmentation of cytokine release compared with stimulation through the activation receptor alone. These results demonstrate that NKG2D has the ability to costimulate multiple NK activation receptors.
Physiological Mechanisms of Regulating Alloimmunity: Cytokines, CTLA-4, CD25+ Cells, and the Alloreactive T Cell Clone Size
Authors: Sho Masayuki , Yamada Akira , Najafian Nader , Salama Alan D. , Harada Hiroshi , Sandner Sigrid E. , Sanchez-Fueyo Alberto , Zheng Xin Xiao , Strom Terry B. , Sayegh Mohamed H. 
Published: April 2014

AbstractThe mechanisms underlying physiological regulation of alloimmune responses remain poorly defined. We investigated the roles of cytokines, CTLA-4, CD25+ T cells, and apoptosis in regulating alloimmune responses in vivo. Two murine cardiac transplant models were used, B10.D2 (minor mismatch) and C57BL/6 (major mismatch), into BALB/c recipients. Recipients were wild type, STAT4−/− (Th1 deficient), or STAT6−/− (Th2 deficient) mice. Minor mismatched allografts were accepted spontaneously in ∼70% of wild type and STAT4−/− mice. By contrast, there was significantly shorter graft survival in minor mismatched STAT6−/− mice. Either the adoptive transfer of STAT4−/− splenocytes or the administration of IL-4Fc fusion protein into STAT6−/− mice resulted in long term graft survival. Blocking CTLA-4 signaling accelerated the rejection in all recipients, but was more pronounced in the minor combination. This was accompanied by an increased frequency of alloreactive T cells. Furthermore, CTLA-4 blockade regulated CD4+ or CD8+ as well as Th1 or Th2 alloreactive T cells. Finally, while anti-CD25 treatment prolonged graft survival in the major mismatched combination, the same treatment accelerated graft rejection in the minor mismatched group. The latter was associated with an increased frequency of alloreactive T cells and inhibition of T cell apoptosis. These data demonstrate that cytokine regulation, CTLA-4 negative signaling, and T cell apoptosis play critical roles in regulating alloimmunity, especially under conditions where the alloreactive T cell clone size is relatively small.
TCR and IL-7 Receptor Signals Can Operate Independently or Synergize to Promote Lymphopenia-Induced Expansion of Naive T Cells
Authors: Seddon Benedict , Zamoyska Rose 
Published: April 2014

AbstractTCR and cytokine signals induce naive T cells to undergo spontaneous divisions as part of a homeostatic response to conditions of T cell deficiency. The conditions under which these signals evoke the homeostatic response and their interaction with each other are poorly understood, and yet are very important clinically in considering strategies for immune reconstitution. Here, we show that p56lck (lck)-mediated TCR signals and IL-7R signals are each able to stimulate T cell proliferation in lymphopenic hosts independently of one another, but can also synergize to facilitate proliferation. Furthermore, the relative contribution to the homeostatic response by TCR and cytokine signals is not fixed and critically depends on both the degree of lymphopenia and specific characteristics of individual T cell clones. Finally, we show that only lck and not fyn can mediate the TCR-driven proliferation, while neither lck nor fyn is required for IL-7R-induced proliferation.
Differential Sensitivity of Naive and Memory CD8+ T Cells to Apoptosis in Vivo
Authors: Grayson Jason M. , Harrington Laurie E. , Lanier J. Gibson , Wherry E. John , Ahmed Rafi 
Published: April 2014

Abstract
Apoptosis is a critical regulator of homeostasis in the immune system. In this study we demonstrate that memory CD8+ T cells are more resistant to apoptosis than naive cells. After whole body irradiation of mice, both naive and memory CD8+ T cells decreased in number, but the reduction in the number of naive cells was 8-fold greater than that in memory CD8+ T cells. In addition to examining radiation-induced apoptosis, we analyzed the expansion and contraction of naive and memory CD8+ T cells in vivo following exposure to Ag. We found that memory CD8+ T cells not only responded more quickly than naive cells after viral infection, but that secondary effector cells generated from memory cells underwent much less contraction compared with primary effectors generated from naive cells (3- to 5-fold vs 10- to 20-fold decrease). Increased numbers of secondary memory cells were observed in both lymphoid and non-lymphoid tissues. When naive and memory cells were transferred into the same animal, secondary effectors underwent less contraction than primary effector cells. These experiments analyzing apoptosis of primary and secondary effectors in the same animal show unequivocally that decreased downsizing of the secondary response reflects an intrinsic property of the memory T cells and is not simply due to environmental effects. These findings have implications for designing prime/boost vaccine strategies and also for optimizing immunotherapeutic regimens for treatment of chronic infections.
Th2 Cytokine Production from Mast Cells Is Directly Induced by Lipopolysaccharide and Distinctly Regulated by c-Jun N-Terminal Kinase and p38 Pathways
Authors: Masuda Akio , Yoshikai Yasunobu , Aiba Keiko , Matsuguchi Tetsuya 
Published: April 2014

AbstractMast cells secrete multiple cytokines and play an important role in allergic inflammation. Although it is widely accepted that bacteria infection occasionally worsens allergic airway inflammation, the mechanism has not been defined. In this study, we show that LPS induced Th2-associated cytokine production such as IL-5, IL-10, and IL-13 from mast cells and also synergistically enhanced production of these cytokines induced by IgE cross-linking. LPS-mediated Th2-type cytokine production was abolished in mouse bone marrow-derived mast cells derived from C3H/HeJ mice, suggesting that Toll-like receptor 4 is essential for the cytokine production. Furthermore, we found that mitogen-activated protein kinases including extracellular signal-regulated kinase 1/2, c-Jun N-terminal kinase, and p38 kinase were activated by LPS stimulation in bone marrow-derived mast cells. Inhibition of extracellular signal-regulated kinase activation has little effect on LPS-mediated cytokine production. In contrast, inhibition of c-Jun N-terminal kinase activation significantly suppressed both IL-10 and IL-13 expression at both mRNA and protein levels. Interestingly, although inhibition of p38 did not down-regulate the mRNA induction, it moderately decreased all three cytokine productions by LPS. These results indicate that LPS-mediated production of IL-5, IL-10, and IL-13 was distinctly regulated by mitogen-activated protein kinases. Our findings may indicate a clue to understanding the mechanisms of how bacteria infection worsens the clinical features of asthma.
IL-4 Induces the Proteolytic Processing of Mast Cell STAT6
Authors: Sherman Melanie A. , Powell Doris R. , Brown Melissa A. 
Published: April 2014

AbstractIL-4 is a potent, pleiotropic cytokine that, in general, directs cellular activation, differentiation, and rescue from apoptosis. However, in mast cells, IL-4 induces the down-regulation of activation receptors and promotes cell death. Mast cells have been shown to transduce IL-4 signals through a unique C-terminally truncated isoform of STAT6. In this study, we examine the mechanism through which STAT6 is processed to generate this isoform. We demonstrate that STAT6 processing in mast cells is initiated by IL-4-induced phosphorylation and nuclear translocation of full-length STAT6 and subsequent cleavage by a nuclear serine-family protease. The location of the protease in the nucleus ensures that the truncated STAT6 has preferential access to bind DNA. IL-4-responsive target genes in mast cells are identified by chromatin immunoprecipitation of STAT6, including the IL-4 gene itself. These results suggest a molecular explanation for the suppressive effects of IL-4 on STAT6-regulated genes in mast cells.
Complement Inhibitor Factor H Binding to Lyme Disease Spirochetes Is Mediated by Inducible Expression of Multiple Plasmid-Encoded Outer Surface Protein E Paralogs
Authors: Alitalo Antti , Meri Taru , Lankinen Hilkka , Seppälä Ilkka , Lahdenne Pekka , Hefty P. Scott , Akins Darrin , Meri Seppo 
Published: April 2014

Abstract
Borrelia burgdorferi spirochetes can circumvent the vertebrate host’s immune system for long periods of time. B. burgdorferi sensu stricto and B. afzelii, but not B. garinii, bind the complement inhibitor factor H to protect themselves against complement-mediated opsonophagocytosis and killing. We found that factor H binding and complement resistance are due to inducible expression of a wide repertoire of outer surface protein E (OspE) lipoproteins variably called OspE, p21, ErpA, and ErpP. Individual Borrelia strains carry multiple plasmid-encoded OspE paralogs. Together the OspE homologs were found to constitute an array of proteins that bind factor H via multiple C-terminal domains that are exposed outwards from the Borrelial surface. Charged residue substitutions in the key binding regions account for variations between OspE family members in the optimal binding pH, temperature, and ionic strength. This may help the spirochetes to adapt into various host environments. Our finding that multiple plasmid-encoded OspE proteins act as virulence factors of Borrelia can provide new tools for the prevention and treatment of borreliosis.
Critical Roles of Myeloid Differentiation Factor 88-Dependent Proinflammatory Cytokine Release in Early Phase Clearance ofListeria monocytogenesin Mice
Authors: Seki Ekihiro , Tsutsui Hiroko , Tsuji Noriko M. , Hayashi Nobuki , Adachi Keishi , Nakano Hiroki , Futatsugi-Yumikura Shizue , Takeuchi Osamu , Hoshino Katsuaki , Akira Shizuo , Fujimoto Jiro , Nakanishi Kenji 
Published: April 2014

AbstractListeria monocytogenes (LM), a facultative intracellular Gram-positive bacterium, often causes lethal infection of the host. In this study we investigated the molecular mechanism underlying LM eradication in the early phase of infection. Upon infection with LM, both IL-12 and IL-18 were produced, and then they synergistically induced IFN-γ production, leading to normal LM clearance in the host. IFN-γ knockout (KO) mice were highly susceptible to LM infection. IL-12/IL-18 double knockout mice were also highly susceptible. Their susceptibility was less than that of IFN-γ KO mice, but more than that of single IL-12 or IL-18 KO mice. Mice deficient in myeloid differentiation factor 88 (MyD88), an essential adaptor molecule used by signal transduction pathways of all members of the Toll-like receptor (TLR) family, showed an inability to produce IL-12 and IFN-γ following LM infection and were most susceptible to LM. Furthermore, MyD88-deficient, but not IFN-γ-deficient, Kupffer cells could not produce TNF-α in response to LM in vitro, indicating the importance of MyD88-dependent TNF-α production for host defense. As TLR2 KO, but not TLR4 KO, mice showed partial impairment in their capacity to produce IL-12, IFN-γ, and TNF-α, TLR2 activation partly contributed to the induction of IL-12-mediated IFN-γ production. These results indicated a critical role for TLRs/MyD88-dependent IL-12/TNF-α production and for IL-12- and IL-18-mediated IFN-γ production in early phase clearance of LM.
MyD88-Dependent but Toll-Like Receptor 2-Independent Innate Immunity to Listeria: No Role for Either in Macrophage Listericidal Activity
Authors: Edelson Brian T. , Unanue Emil R. 
Published: April 2014

Abstract
We have assessed the requirements for Toll-like receptor (TLR) signaling in vivo during early infection with Listeria monocytogenes. Mice deficient for TLR2, a receptor required for the recognition of Gram-positive peptidoglycan, showed equivalent Listeria resistance to wild-type mice. However, mice deficient for MyD88, an adaptor molecule used by all TLRs, showed profound susceptibility with 3–4 logs greater Listeria burden and severe spleen and liver pathology at day 3 postinfection. Listeria-infected MyD88-deficient mice also showed markedly diminished IFN-γ, TNF-α, and NO responses, despite evidence of macrophage activation and up-regulation of MHC class II molecules. We demonstrate that although minor MyD88-independent responses to live Listeria do occur, these are insufficient for normal host defense. Lastly, we performed experiments in vitro in which macrophages deficient in TLR2 or MyD88 were directly infected with Listeria. Although TLR signaling was required for macrophage NO and cytokine production in response to Listeria, handling and direct killing of Listeria by activated macrophages occurred by TLR2- and MyD88-independent mechanisms.
The Human Antimicrobial Peptide LL-37 Is a Multifunctional Modulator of Innate Immune Responses
Authors: Scott Monisha G. , Davidson Donald J. , Gold Michael R. , Bowdish Dawn , Hancock Robert E. W. 
Published: April 2014

Abstract
The role of LL-37, a human cationic antimicrobial peptide, in the immune system is not yet clearly understood. It is a widely expressed peptide that can be up-regulated during an immune response. In this report, we demonstrate that LL-37 is a potent antisepsis agent with the ability to inhibit macrophage stimulation by bacterial components such as LPS, lipoteichoic acid, and noncapped lipoarabinomannan. We also demonstrate that LL-37 protects mice against lethal endotoxemia. In addition to preventing macrophage activation by bacterial components, we hypothesized the LL-37 may also have direct effects on macrophage function. We therefore used gene expression profiling to identify macrophage functions that might be modulated by LL-37. These studies revealed that LL-37 directly up-regulates 29 genes and down-regulated another 20 genes. Among the genes predicted to be up-regulated by LL-37 were those encoding chemokines and chemokine receptors. Consistent with this, LL-37 up-regulated the expression of chemokines in macrophages and the mouse lung (monocyte chemoattractant protein 1), human A549 epithelial cells (IL-8), and whole human blood (monocyte chemoattractant protein 1 and IL-8), without stimulating the proinflammatory cytokine, TNFα. LL-37 also up-regulated the chemokine receptors CXCR-4, CCR2, and IL-8RB. These findings indicate that LL-37 may contribute to the immune response by limiting the damage caused by bacterial products and by recruiting immune cells to the site of infection so that they can clear the infection.
Peritumoral CpG DNA Elicits a Coordinated Response of CD8 T Cells and Innate Effectors to Cure Established Tumors in a Murine Colon Carcinoma Model
Authors: Heckelsmiller Klaus , Rall Katharina , Beck Sebastian , Schlamp Angelika , Seiderer Julia , Jahrsdörfer Bernd , Krug Anne , Rothenfusser Simon , Endres Stefan , Hartmann Gunther 
Published: April 2014

AbstractThe immune system of vertebrates is able to detect bacterial DNA based on the presence of unmethylated CpG motifs. We examined the therapeutic potential of oligodeoxynucleotides with CpG motifs (CpG ODN) in a colon carcinoma model in BALB/c mice. Tumors were induced by s.c. injection of syngeneic C26 cells or Renca kidney cancer cells as a control. Injection of CpG ODN alone or in combination with irradiated tumor cells did not protect mice against subsequent tumor challenge. In contrast, weekly injections of CpG ODN into the margin of already established tumors resulted in regression of tumors and complete cure of mice. The injection site was critical, since injection of CpG ODN at distant sites was not effective. Mice with two bilateral C26 tumors rejected both tumors upon peritumoral injection of one tumor, indicating the development of a systemic immune response. The tumor specificity of the immune response was demonstrated in mice bearing a C26 tumor and a Renca tumor at the same time. Mice that rejected a tumor upon peritumoral CpG treatment remained tumor free and were protected against rechallenge with the same tumor cells, but not with the other tumor, demonstrating long term memory. Tumor-specific CD8 T cells as well as innate effector cells contributed to the antitumor activity of treatment. In conclusion, peritumoral CpG ODN monotherapy elicits a strong CD8 T cell response and innate effector mechanisms that seem to act in concert to overcome unresponsiveness of the immune system toward a growing tumor.
Critical Components of a DNA Fusion Vaccine Able to Induce Protective Cytotoxic T Cells Against a Single Epitope of a Tumor Antigen
Authors: Rice Jason , Buchan Sarah , Stevenson Freda K. 
Published: April 2014

AbstractDNA vaccines can activate immunity against tumor Ags expressed as MHC class I-associated peptides. However, priming of CD8+ CTL against weak tumor Ags may require adjuvant molecules. We have used a pathogen-derived sequence from tetanus toxin (fragment C (FrC)) fused to tumor Ag sequences to promote Ab and CD4+ T cell responses. For induction of CD8+ T cell responses, the FrC sequence has been engineered to remove potentially competitive MHC class I-binding epitopes and to improve presentation of tumor epitopes. The colon carcinoma CT26 expresses an endogenous retroviral gene product, gp70, containing a known H2-Ld-restricted epitope (AH1). A DNA vaccine encoding gp70 alone was a poor inducer of CTL, and performance was not significantly improved by fusion of full-length FrC. However, use of a minimized domain of FrC, with the AH1 sequence fused to the 3′ position, led to rapid induction of high levels of CTL. IFN-γ-producing epitope-specific CTL were detectable ex vivo and these killed CT26 targets in vitro. The single epitope vaccine was more effective than GM-CSF-transfected CT26 tumor cells in inducing an AH1-specific CTL response and equally effective in providing protection against tumor challenge. Levels of AH1-specific CTL in vivo were increased following injection of tumor cells, and CTL expanded in vitro were able to kill CT26 cells in tumor bearers. Pre-existing immunity to tetanus toxoid had no effect on the induction of AH1-specific CTL. These data demonstrate the power of epitope-specific CTL against tumor cells and illustrate a strategy for priming immunity via a dual component DNA vaccine.
Bacterial Flagellin Is an Effective Adjuvant for CD4+ T Cells In Vivo
Authors: McSorley Stephen J. , Ehst Benjamin D. , Yu Yimin , Gewirtz Andrew T. 
Published: April 2014

AbstractFlagellin is secreted by many enteric bacteria and, upon reaching the basolateral membrane of the intestinal epithelium, activates Toll-like receptor 5-mediated innate immune signaling pathways. We hypothesized that any flagellin that gets beyond the epithelium might also regulate cells of the adaptive immune system. Here we demonstrate that the clonal expansion of naive DO11.10 CD4 T cells in response to OVA peptide (323–339) was enhanced 3- to 10-fold in the presence of purified bacterial flagellin in vivo. OVA-specific CD4 T cells were also shown to have undergone more cell division in vivo if flagellin was coinjected with OVA. Flagellin administration increased the expression of B7-1 on splenic dendritic cells, and coinjection of CTLA4-Ig, which is known to block B7 function in vivo, completely ablated the adjuvant effect on CD4 T cells. Therefore, a conserved bacterial protein produced by many intestinal microbes can modulate CD4 T cell activation in vivo. Such an adjuvant effect for flagellin has important implications for vaccine development and the generation of CD4 T cell responses to enteric bacteria.
Glycosylphosphatidylinositol-Anchored Mucin-Like Glycoproteins fromTrypanosoma cruziBind to CD1d but Do Not Elicit Dominant Innate or Adaptive Immune Responses Via the CD1d/NKT Cell Pathway
Authors: Procópio Daniela O. , Almeida Igor C. , Torrecilhas Ana Cláudia T. , Cardoso Jarbas E. , Teyton Luc , Travassos Luiz R. , Bendelac Albert , Gazzinelli Ricardo T. 
Published: April 2014

AbstractIt has been proposed that self and protozoan-derived GPI anchors are natural ligands of CD1d. In this study, we investigated the ability of GPI anchors from Trypanosoma cruzi to bind to CD1d and mediate activation of NKT cells. We observed that GPI-anchored mucin-like glycoproteins (GPI mucins), glycoinositolphospholipids (GIPLs), and their phosphatidylinositol moieties bind to rCD1d and inhibit the stimulation of a NKT hybridoma by the α-galactosylceramide-CD1 complex. However, these GPI anchors and related structures were unable to activate NKT cells in vitro or in vivo. We found that high titers of Ab anti-GPI mucins, but not anti-GIPLs, were detected in sera from wild-type as well as in TAP1−/−, CD1d−/−, and MHC class II−/− mice after immunization. However, T-dependent anti-GPI mucin Ab isotypes, such as IgG1, IgG2a, IgG2b, and IgG3, were absent on MHC class II−/−, but were conserved in CD1d−/− and TAP1−/− mice. Furthermore, we found that CD1d−/− mice presented a robust cytokine as well as anti-GPI mucins and anti-GIPL Ab responses, upon infection with T. cruzi parasites. These results indicate that, despite binding to CD1d, GPI mucins and related structures expressed by T. cruzi appear not to evoke dominant CD1d-restricted immune responses in vivo. In contrast, MHC class II is critical for the production of the major Ig G isotypes against GPI mucins from T. cruzi parasites.