bluuebunny/crossref_metadata_2025_split huggingface dataset:
Does CD40 Ligation Induce B Cell Negative Selection?
Authors: Martínez-Barnetche Jesús , Madrid-Marina Vicente , Flavell Richard A. , Moreno José 
Published: April 2014

AbstractBinding of CD154 to its receptor, CD40, provides costimulation for mature B cell activation and differentiation in response to Ag receptor signals. In mice, early B cell precursors express CD40, but its function at this stage is unknown. We examined the effects of CD40 ligation during B cell ontogeny in transgenic mice constitutively expressing CD154 on B cells (κEP-CD154). Precursors beyond pro-B cells were absent in adult bone marrow but were increased in the fetal liver. Newborn κEP-CD154 mice had largely increased numbers of peripheral B cells, which were CD154+, and that 36 h after birth expressed high surface levels of CD23 and MHC class II, resembling activated mature B cells. Nevertheless, κEP-CD154 mice were hypogammaglobulinemic, indicating that the expanded population of apparently activated B cells was nonfunctional. Further analysis revealed that soon after birth, κEP-CD154 mice-derived B cells became CD5+/Fas+, after which progressively decreased in the periphery in a CD154-CD40-dependent manner. These results indicate that CD40 ligation during B cell ontogeny induces negative selection characterized by either hyporesponsiveness or an arrest in maturation depending on the time of analysis and the anatomic site studied.
Withdrawal of Stimulation May Initiate the Transition of Effector to Memory CD4 Cells
Authors: Harbertson Judith , Biederman Elana , Bennett Kristin E. , Kondrack Robyn M. , Bradley Linda M. 
Published: April 2014

AbstractThe initial steps that determine development of memory in CD4 cells are unknown. To distinguish an intrinsic capacity of effectors to become memory cells from contributions of as yet undefined survival factors, we analyzed the effects of withdrawal of signals via TCR, costimulation, and cytokines from Th1 or Th2 primary effectors induced in vitro from TCR-transgenic CD4 cells. Withdrawal of stimulation caused the transition of effectors to resting populations with a memory phenotype that did not undergo division following transfer to normal syngeneic recipients. The return of effectors to rest was accompanied by acquisition of the capacity to function as memory cells in vivo as defined by extended persistence and a more rapid response to Ag in vivo than naive cells in adoptive hosts. Upon challenge with Ag, these in vitro-rested Th1 and Th2 cells were similar to long-term in vivo-rested memory cells, but distinct from in vitro-generated primary effectors and in vivo-restimulated memory effectors by their ability to resist apoptosis. Cessation of stimulation may occur when activated CD4 cells exit lymphoid tissues after priming and transition to memory may be initiated if effectors either fail to gain access to Ag in peripheral tissues where restimulation can lead to activation-induced cell death or do not receive sufficient stimuli to continue a response. Our results suggest that the first stage leading to stable CD4 memory could occur stochastically and independently of instructional processes and as such, the development of memory may be a default pathway when signals that direct responses are not received.
Synergy of IL-12 and IL-18 for IFN-γ Gene Expression: IL-12-Induced STAT4 Contributes to IFN-γ Promoter Activation by Up-Regulating the Binding Activity of IL-18-Induced Activator Protein 1
Authors: Nakahira Masakiyo , Ahn Hyun-Jong , Park Woong-Ryeon , Gao Ping , Tomura Michio , Park Cheung-Seog , Hamaoka Toshiyuki , Ohta Tsunetaka , Kurimoto Masashi , Fujiwara Hiromi 
Published: April 2014

AbstractIL-12 and IL-18 synergistically enhance IFN-γ mRNA transcription by activating STAT4 and AP-1, respectively. However, it is still unknown how STAT4/AP-1 elicit IFN-γ promoter activation. Using an IL-12/IL-18-responsive T cell clone, we investigated the mechanisms underlying synergistic enhancement of IFN-γ mRNA expression induced by these two cytokines. Synergy was observed in a reporter gene assay using an IFN-γ promoter fragment that binds AP-1, but not STAT4. An increase in c-Jun, a component of AP-1, in the nuclear compartment was elicited by stimulation with either IL-12 or IL-18, but accumulation of serine-phosphorylated c-Jun was induced only by IL-18 capable of activating c-Jun N-terminal kinase. The binding of AP-1 to the relevant promoter sequence depended on the presence of STAT4. STAT4 bound with c-Jun, and a phosphorylated c-Jun-STAT4 complex most efficiently interacted with the AP-1-relevant promoter sequence. Enhanced cobinding of STAT4 and c-Jun to the AP-1 sequence was also observed when activated lymph node T cells were exposed to IL-12 plus IL-18. These results show that STAT4 up-regulates AP-1-mediated IFN-γ promoter activation without directly binding to the promoter sequence, providing a mechanistic explanation for IL-12/IL-18-induced synergistic enhancement of IFN-γ gene expression.
Mechanisms of Central Nervous System Viral Persistence: the Critical Role of Antibody and B Cells
Authors: Ramakrishna Chandran , Stohlman Stephen A. , Atkinson Roscoe D. , Shlomchik Mark J. , Bergmann Cornelia C. 
Published: April 2014

AbstractContributions of humoral and cellular immunity in controlling neurotropic mouse hepatitis virus persistence within the CNS were determined in B cell-deficient JHD and syngeneic H-2d B cell+ Ab-deficient mice. Virus clearance followed similar kinetics in all mice, confirming initial control of virus replication by cellular immunity. Nevertheless, virus reemerged within the CNS of all Ab-deficient mice. In contrast to diminished T cell responses in H-2b B cell-deficient μMT mice, the absence of B cells or Ab in the H-2d mice did not compromise expansion, recruitment into the CNS, or function of virus-specific CD4+ and CD8+ T cells. The lack of B cells and lymphoid architecture thus appears to manifest itself on T cell responses in a genetically biased manner. Increasing viral load did not enhance frequencies or effector function of virus-specific T cells within the CNS, indicating down-regulation of T cell responses. Although an Ab-independent antiviral function of B cells was not evident during acute infection, the presence of B cells altered CNS cellular tropism during viral recrudescence. Reemerging virus localized almost exclusively to oligodendroglia in B cell+ Ab-deficient mice, whereas it also replicated in astrocytes in B cell-deficient mice. Altered tropism coincided with distinct regulation of CNS virus-specific CD4+ T cells. These data conclusively demonstrate that the Ab component of humoral immunity is critical in preventing virus reactivation within CNS glial cells. B cells themselves may also play a subtle role in modulating pathogenesis by influencing tropism.
CpG Are Efficient Adjuvants for Specific CTL Induction Against Tumor Antigen-Derived Peptide
Authors: Miconnet Isabelle , Koenig Sylvain , Speiser Daniel , Krieg Arthur , Guillaume Philippe , Cerottini Jean-Charles , Romero Pedro 
Published: April 2014

AbstractThe identification of CTL-defined tumor-associated Ags has allowed the development of new strategies for cancer immunotherapy. To potentiate the CTL responses, peptide-based vaccines require the coadministration of adjuvants. Because oligodeoxynucleotides (ODN) containing CpG motifs are strong immunostimulators, we analyzed the ability of CpG ODN to act as adjuvant of the CTL response against tumor-derived synthetic peptide in the absence or presence of IFA. Mice transgenic for a chimeric MHC class I molecule were immunized with a peptide analog of MART-1/Melan-A26–35 in the presence of CpG ODN alone or CpG ODN emulsified in IFA. The CTL response was monitored ex vivo by tetramer staining of lymphocytes. In blood, spleen, and lymph nodes, peptide mixed with CpG ODN alone was able to elicit a stronger systemic CTL response as compared with peptide emulsified in IFA. Moreover, CpG ODN in combination with IFA further enhanced the CTL response in terms of the frequency of tetramer+CD8+ T cells ex vivo. The CTL induced in vivo against peptide analog in the presence of CpG ODN are functional, as they were able to recognize and kill melanoma cells in vitro. Overall, these results indicate that CpG ODN by itself is a good candidate adjuvant of CTL response and can also enhance the effect of classical adjuvant.
Regulation of Human Igλ Light Chain Gene Expression by NF-κB
Authors: Combriato Gabriele , Klobeck H.-Gustav 
Published: April 2014

Abstract
The human Igλ enhancer consists of three separated sequence elements that we identified previously by mapping DNase I-hypersensitive regions (HSS) downstream of the C region of the Igλ L chain genes (HSS-1, HSS-2, and HSS-3). It has been shown by several laboratories that expression of the H chain genes as well as the κ genes, but not the λ genes, is dependent on constitutive NF-κB proteins present in the nucleus. In this study we show by band-shift experiments, in vivo footprinting, and transient transfection assays that all three hypersensitive sites of the human Igλ enhancer contain functional NF-κB sites that act synergistically on expression. We further show that the chicken λ enhancer also contains a functional NF-κB site but the mouse λ enhancer contains a mutated, nonfunctional NF-κB site that is responsible for its low enhancer activity. It is possible that the inactivating mutation in the mouse Igλ enhancer was compensated for by an expansion of the Igκ L chain locus, followed by a contraction of the Igλ locus in this species.
C-Terminal Anchoring of a Peptide to Class II MHC Via the P10 Residue Is Compatible with a Peptide Bulge
Authors: Yassai Maryam , Afsari Amin , Garlie Jason , Gorski Jack 
Published: April 2014

AbstractThe binding of antigenic peptide to class II MHC is mediated by hydrogen bonds between the MHC and the peptide, by salt bridges, and by hydrophobic interactions. The latter are confined to a number of deeper pockets within the peptide binding groove, and peptide side chains that interact with these pockets are referred to as anchor residues. T cell recognition involves solvent-accessible peptide residues along with minor changes in MHC helical pitch induced by the anchor residues. In class I MHC there is an added level of epitope complexity that results from binding of longer peptides that bulge out into the solvent-accessible, T cell contact area. Unlike class I MHC, class II MHC does not bind peptides of discrete length, and the possibility of peptide bulging has not been clearly addressed. A peptide derived from position 24–37 of integrin β3 can either bind or not bind to the class II MHC molecule HLA DRB3*0101 based on a polymorphism at the P9 anchor. We show that the loss of binding can be compensated by changes at the P10 position. We propose that this could be an example of a class II peptide bulge. Although not as efficient as P9 anchoring, the use of P10 as an anchor adds another possible mechanism by which T cell epitopes can be generated in the class II presentation system.
In Vivo Expression of Toll-Like Receptor 2 and 4 by Renal Epithelial Cells: IFN-γ and TNF-α Mediated Up-Regulation During Inflammation
Authors: Wolfs Tim G. A. M. , Buurman Wim A. , van Schadewijk Annemarie , de Vries Bart , Daemen Marc A. R. C. , Hiemstra Pieter S. , van ’t Veer Cornelis 
Published: April 2014

AbstractThe reported requirement of functional Toll-like receptor (TLR)4 for resistance to Gram-negative pyelonephritis prompted us to localize the expression of TLR2 and TLR4 mRNA in the kidney at the cellular level by in situ hybridization. The majority of the constitutive TLR2 and TLR4 mRNA expression was found to be strategically located in the renal epithelial cells. Assuming that the TLR mRNA expression is representative of apical protein expression, this suggests that these cells are able to detect and react with bacteria present in the lumen of the tubules. To gain insight in the regulation of TLR expression during inflammation, we used a model for renal inflammation. Renal inflammation evoked by ischemia markedly enhanced synthesis of TLR2 and TLR4 mRNA in the distal tubular epithelium, the thin limb of Henle’s loop, and collecting ducts. The increased renal TLR4 mRNA expression was associated with significant elevation of renal TLR4 protein expression as evaluated by Western blotting. Using RT-PCR, the enhanced TLR2 and TLR4 mRNA expression was shown to be completely dependent on the action of IFN-γ and TNF-α. These results indicate a potential mechanism of increased immunosurveillance during inflammation at the site in which ascending bacteria enter the kidney tissue, i.e., the collecting ducts and the distal part of the nephron.
Dendritic Cells Are Host Cells for Mycobacteria In Vivo That Trigger Innate and Acquired Immunity
Authors: Jiao Xinan , Lo-Man Richard , Guermonprez Pierre , Fiette Laurence , Dériaud Edith , Burgaud Sophie , Gicquel Brigitte , Winter Nathalie , Leclerc Claude 
Published: April 2014

AbstractIn the present study, we investigated in vivo the infection and APC functions of dendritic cells (DC) and macrophages (Mφ) after administration of live mycobacteria to mice. Experiments were conducted with Mycobacterium bovis bacillus Calmette-Guerin (BCG) or a rBCG expressing a reporter Ag. Following infection of mice, DC and Mφ were purified and the presence of immunogenic peptide/MHC class II complexes was detected ex vivo on sorted cells, as was the secretion of IL-12 p40. We show in this study that DC is a host cell for mycobacteria, and we provide an in vivo detailed picture of the role of Mφ and DC in the mobilization of immunity during the early stages of a bacterial infection. Strikingly, BCG bacilli survive but remain stable in number in the DC leukocyte subset during the first 2 wk of infection. As Ag presentation by DC is rapidly lost, this suggests that DC may represent a hidden reservoir for mycobacteria.
CD28 Costimulation and Parasite Dose Combine to Influence the Susceptibility of BALB/c Mice to Infection withLeishmania major
Authors: Compton Helen L. , Farrell Jay P. 
Published: April 2014

AbstractInfection with Leishmania major in BALB/c mice is accompanied by the development of a nonprotective Th2-type response. It has previously been shown that disease progression, and the activation of a Th2-type response, can occur in the absence of CD28 costimulation following the inoculation of high numbers of L. major promastigotes. In this study, we show that in the absence of CD28-B7 interactions, BALB/c mice can spontaneously resolve their infections following the inoculation of low numbers of parasites. BALB/c CD28+/+ and CD28−/− mice were inoculated with 250, 500, and 750 metacyclic parasites. The CD28−/− mice controlled their lesions, whereas the wild-type (WT) mice developed progressive nonhealing infections. Resistance to infection was associated with reduced numbers of parasites in the CD28−/− mice compared with the WT mice. Infection of the CD28−/− mice resulted in the activation of a Th1-type response as evidenced by increased levels of mRNA for IFN-γ and reduced levels of message for IL-4 and IL-10 in draining lymph nodes compared with those in WT mice. Healing of infected CD28−/− mice could also be ablated with anti-CD4 Ab treatment or treatment with anti-IFN-γ Ab. In addition, healed CD28−/− mice were resistant to a challenge infection with L. major. These results suggest that CD28 costimulation influences the in vivo activation of a Th2-type response in a manner that is dependent on the size of the parasite inoculum.
Surfactant Protein D Inhibition of Human Macrophage Uptake ofMycobacterium tuberculosisIs Independent of Bacterial Agglutination
Authors: Ferguson J. Scott , Voelker Dennis R. , Ufnar Jennifer A. , Dawson Amanda J. , Schlesinger Larry S. 
Published: April 2014

AbstractThe innate immune system in the lung is essential for controlling infections due to inhaled pathogens. Mycobacterium tuberculosis (M.tb) encounters components of the innate immune system when inhaled into the lung, but the consequences of these interactions are poorly understood. Surfactant protein D (SP-D) binds to and agglutinates M.tb bacilli, and reduces the uptake of the bacteria by human macrophages. In the current studies, we utilized a recombinant SP-D variant (CDM) that lacks the collagen domain to further characterize the interaction of SP-D with M.tb, and determine the effects of agglutination on bacterial uptake by human monocyte-derived macrophages. These studies demonstrate that the binding of SP-D and CDM to M.tb is saturable and inhibited by carbohydrate competition and Ca2+ chelation, implicating the carbohydrate recognition domain in the interaction. Fluorescence microscopy reveals that dodecameric SP-D leads to agglutination of the bacilli, whereas the trimeric CDM does not, demonstrating that the multivalent nature of SP-D is essential for agglutination of M.tb. However, preincubation of M.tb with increasing concentrations of SP-D or CDM leads to a concentration-dependent reduction in the uptake of the bacteria by macrophages, indicating that agglutination does not play a direct role in this observation. Finally, the reduced uptake of M.tb by SP-D is associated with reduced growth of M.tb in monocyte-derived macrophages. These studies provide direct evidence that the inhibition of phagocytosis of M.tb effected by SP-D occurs independently of the aggregation process.
Induction of TNF in Human Alveolar Macrophages As a Potential Evasion Mechanism of VirulentMycobacterium tuberculosis
Authors: Engele Matthias , Stöβel Elmar , Castiglione Kirstin , Schwerdtner Nives , Wagner Manfred , Bölcskei Pal , Röllinghoff Martin , Stenger Steffen 
Published: April 2014

AbstractThe ability of macrophages to release cytokines is crucial to the host response to intracellular infection. In particular, macrophage-derived TNF plays an important role in the host response to infection with the intracellular pathogen Mycobacterium tuberculosis. In mice, TNF is indispensable for the formation of tuberculous granulomas, which serve to demarcate the virulent bacterium. TNF is also implicated in many of the immunopathological features of tuberculosis. To investigate the role of TNF in the local immune response, we infected human alveolar macrophages with virulent and attenuated mycobacteria. Infection with virulent strains induced the secretion of significantly higher levels of bioactive TNF than attenuated strains correlating with their ability to multiply intracellularly. Treatment of infected macrophages with neutralizing anti-TNF Abs reduced the growth rate of intracellular bacteria, whereas bacterial replication was augmented by addition of exogenous TNF. Infected and uninfected macrophages contributed to cytokine production as determined by double-staining of M. tuberculosis and intracellular TNF. The induction of TNF by human alveolar macrophages at the site of infection permits the multiplication of intracellular bacteria and may therefore present an evasion mechanism of human pathogens.
Increased Susceptibility to Tumor Initiation and Metastasis in TNF-Related Apoptosis-Inducing Ligand-Deficient Mice
Authors: Cretney Erika , Takeda Kazuyoshi , Yagita Hideo , Glaccum Moira , Peschon Jacques J. , Smyth Mark J. 
Published: April 2014

AbstractWe have previously implicated TNF-related apoptosis-inducing ligand (TRAIL) in innate immune surveillance against tumor development. In this study, we describe the use of TRAIL gene-targeted mice to demonstrate the key role of TRAIL in suppressing tumor initiation and metastasis. Liver and spleen mononuclear cells from TRAIL gene-targeted mice were devoid of TRAIL expression and TRAIL-mediated cytotoxicity. TRAIL gene-targeted mice were more susceptible to experimental and spontaneous tumor metastasis, and the immunotherapeutic value of α-galactosylceramide was diminished in TRAIL gene-targeted mice. TRAIL gene-targeted mice were also more sensitive to the chemical carcinogen methylcholanthrene. These results substantiated TRAIL as an important natural effector molecule used in the host defense against transformed cells.
TNF-α Potentiates C5a-Stimulated Eosinophil Adhesion to Human Bronchial Epithelial Cells: A Role for α5β1 Integrin
Authors: Burke-Gaffney Anne , Blease Kate , Hartnell Adele , Hellewell Paul G. 
Published: April 2014

AbstractCooperative action of inflammatory mediators and adhesion molecules orchestrates eosinophil recruitment during allergic inflammation in the airways. This study investigated the mechanisms involved in increasing eosinophil adhesion to human bronchial epithelial cells (HBEC) following priming and activation of eosinophils with TNF-α and complement protein C5a, respectively. Under primed conditions, eosinophil adhesion increased 3-fold from basal (16%), and the effect was significantly greater (p &lt; 0.05) than the increase following stimulation with C5a alone (2-fold). Eosinophil contact with HBEC was essential for priming. In contrast to C5a, adhesion of eotaxin-stimulated eosinophils to HBEC was not primed with TNF-α nor IL-5, a known eosinophil-priming agent. Priming caused activation of αMβ2 integrin; mAb against either the common β2 integrin subunit or its ICAM-1 ligand reduced the primed component of adhesion. Using mAbs against β1 or α5, but not α4 integrin subunit, together with anti-β2 integrin mAb, reduced stimulated adhesion to basal levels. Cross-linking α5β1 integrin increased αMβ2 integrin-dependent adhesion of eosinophils. There are no known adhesion molecule ligands of α5β1 integrin expressed on HBEC; however, fibronectin, the major matrix protein ligand for α5β1 integrin, was detected in association with HBEC monolayers. A mAb against fibronectin, in combination with anti-β2 integrin mAb, reduced adhesion to basal levels. In conclusion, α5β1 integrin may provide a contact-dependent costimulus for eosinophil priming that, together with TNF-α, potentiated C5a activation of αMβ2 integrin and increased eosinophil adhesion to ICAM-1. Fibronectin, associated with HBEC, may act as a ligand for α5β1 integrin. Dual regulation of eosinophil priming may prevent inappropriate activation of eosinophils in the circulation.
C-Reactive Protein Induces Signaling Through FcγRIIa on HL-60 Granulocytes
Authors: Chi Maoyen , Tridandapani Susheela , Zhong Wangjian , Coggeshall K. Mark , Mortensen Richard F. 
Published: April 2014

Abstract
Human C-reactive protein (CRP) at acute phase levels of 10–200 μg/ml triggered the phosphorylation of FcγRIIa, Syk kinase, and phospholipase Cγ2 in granulocytic HL-60 cells. CRP also stimulated translocation to the membrane of both phospholipase Cγ2 and phosphatidylinositol-3-kinase. The signaling response triggered by CRP was a rapid, early event with kinetics similar to the response elicited by human IgG. Both soluble-aggregated CRP and monomeric CRP cross-linked FcγRII to generate a signal of the same intensity. The results are consistent with signaling through the intrinsic immunoreceptor tyrosine-based activation motif of the cytoplasmic domain of FcγRIIa, the major CRP-receptor on monocytes and neutrophils that is responsible for CRP-mediated phagocytosis. The signaling events driven by CRP have the potential to regulate infiltrating neutrophil activities.