bluuebunny/crossref_metadata_2025_split huggingface dataset:
Differentiation of Monocytic Cell Clones into CD8α+ Dendritic Cells (DC) Suggests that Monocytes Can Be Direct Precursors for Both CD8α+ and CD8α− DC in the Mouse
Authors: Gao Jian-Xin , Liu Xingluo , Wen Jing , Zhang Huiming , Durbin Joan , Liu Yang , Zheng Pan 
Published: April 2014

Abstract
Dendritic cells (DC) are the professional APCs that initiate T cell immune responses. DC can develop from both myeloid and lymphoid progenitors. In the mouse, the CD8α+ DC had been designated as “lymphoid” DC, and CD8α− DC as “myeloid” DC until recently when it was demonstrated that common myeloid progenitors can also give rise to CD8α+ DC in bone marrow chimera mice. However, it is still not clear which committed myeloid lineages differentiate into CD8α+ DC. Because monocytes can differentiate into DC in vivo, the simplest hypothesis is that the CD8α+ DC can be derived from the monocyte/macrophage. In this study we show that cell clones, isolated from CD8α+ DC lymphoma but with a monocytic phenotype (CD11clow/−D11bhighCD8α−I-Alow), can redifferentiate into CD8α+ DC either when stimulated by LPS and CD40L or when they migrate into the lymphoid organs. Maturation of DC in vivo correlated with strong priming of allogeneic T cells. Moreover, the monocytes from cultured splenocytes or peritoneal exudates macrophages of wild-type mice are also capable of differentiating into CD11c+CD8α+ DC after their migration into the draining lymph nodes. Our results suggest that monocytes can be direct precursors for CD11c+CD8α+ DC in vivo. In addition, the monocyte clones described in this study may be valuable for studying the differentiation and function of CD8α+ DC that mediate cross-presentation of Ag to CD8 T cells specific for cell-associate Ags.
Mechanisms of Endotoxin Tolerance in Human Intestinal Microvascular Endothelial Cells
Authors: Ogawa Hitoshi , Rafiee Parvaneh , Heidemann Jan , Fisher Pamela J. , Johnson Nathan A. , Otterson Mary F. , Kalyanaraman Balaraman , Pritchard Kirkwood A. , Binion David G. 
Published: April 2014

Abstract
Lipopolysaccharide (endotoxin) tolerance is well described in monocytes and macrophages, but is less well characterized in endothelial cells. Because intestinal microvascular endothelial cells exhibit a strong immune response to LPS challenge and play a critical regulatory role in gut inflammation, we sought to characterize the activation response of these cells to repeated LPS exposure. Primary cultures of human intestinal microvascular endothelial cells (HIMEC) were stimulated with LPS over 6–60 h and activation was assessed using U937 leukocyte adhesion, expression of E-selectin, ICAM-1, VCAM-1, IL-6, IL-8, manganese superoxide dismutase, HLA-DR, and CD86. Effect of repeat LPS stimulation on HIMEC NF-κB and mitogen-activated protein kinase (MAPK) activation, generation of superoxide anion, and Toll-like receptor 4 expression was characterized. LPS pretreatment of HIMEC for 24–48 h significantly decreased leukocyte adhesion after subsequent LPS stimulation. LPS pretreatment inhibited expression of E-selectin, VCAM-1, IL-6, and CD86, while ICAM-1, IL-8, and HLA-DR were not altered. Manganese superoxide dismutase expression increased with repeated LPS stimulation, with a reduction in intracellular superoxide. NF-κB activation was transiently inhibited by LPS pretreatment for 6 h, but not at later time points. In contrast, p44/42 MAPK, p38 MAPK, and c-Jun N-terminal kinase activation demonstrated inhibition by LPS pretreatment 24 or 48 h prior. Toll-like receptor 4 expression on HIMEC was not altered by LPS. HIMEC exhibit endotoxin tolerance after repeat LPS exposure in vitro, characterized by diminished activation and intracellular superoxide anion concentration, and reduced leukocyte adhesion. HIMEC possess specific mechanisms of immunoregulatory hyporesponsiveness to repeated LPS exposure.
A Model for Antigen-Specific T-Cell Anergy: Displacement of CD4-p56lckSignalosome from the Lipid Rafts by a Soluble, Dimeric Peptide-MHC Class II Chimera
Authors: Thomas Sunil , Kumar Rajeev , Preda-Pais Anca , Casares Sofia , Brumeanu Teodor-D. 
Published: April 2014

AbstractSoluble, dimeric peptide-MHC chimeras were shown to induce Ag-specific T cell anergy in vitro and in vivo. In this study, we describe a mechanism by which a soluble, dimeric peptide MHC class II chimera (DEF) induces Ag-specific T cell anergy. The anergic cells showed a displacement of the CD4-p56lck signaling module from the GM1-rich plasma membrane microdomains (lipid rafts), and subsequently an increase in p59fyn kinase activity, a dominant expression of p21 inhibitory TCR ζ-chain, and a poor phosphorylation and recruitment of ζ-associated protein of 70 kDa kinase to the TCR’s immunoreceptor tyrosine-based activation motifs. The Th1 and Th2 transcription was suppressed and the cells were arrested in the Th0 stage of differentiation. Recovery from DEF anergy occurred late and spontaneously at the expense of low thresholds for activation-induced cell death. In contrast to DEF, a combination of TCR and CD4 mAbs did not induce such alterations or anergy, indicating that the ligand-mediated topology of TCR and CD4 coengagement can differentially affect the T cell function. Our results argue for a model of anergy in which the defective partitioning of signaling molecules in lipid rafts is an early, negative signaling event in T cells. Physiological ligands like DEF chimeras may provide new tools for silencing the autoimmune processes, and may also help in deciphering new mechanisms of negative regulation in T cells.
Acquisition of Viral Receptor by NK Cells Through Immunological Synapse
Authors: Tabiasco Julie , Vercellone Alain , Meggetto Fabienne , Hudrisier Denis , Brousset Pierre , Fournié Jean-Jacques 
Published: April 2014

AbstractOccasional EBV infection of human NK cells may lead to malignant diseases such as naso-pharyngeal NK lymphoma although NK cells do not express CD21, the primary receptor for EBV. Here we show that during early EBV infection in patients, NK cells attacked EBV-infected autologous B cells. In vitro, NK cells activated by conjugation to CD21+ B-EBV cell targets transiently acquired a weak CD21+ phenotype by synaptic transfer of few receptor molecules onto their own membrane. In the presence of viral particles, these ectopic receptors allowed EBV binding to the novel NK cell host. Hence, trans-synaptic acquisition of viral receptor from target cells might constitute an unsuspected mode of infection for otherwise unreachable lymphoid hosts.
Ephrin-A1 Induces c-Cbl Phosphorylation and EphA Receptor Down-Regulation in T Cells
Authors: Sharfe Nigel , Freywald Andrew , Toro Ana , Roifman Chaim M. 
Published: April 2014

AbstractEph receptor tyrosine kinases are expressed by T lineage cells, and stimulation with their ligands, the ephrins, has recently been shown to modulate T cell behavior. We show that ephrin-A1 stimulation of Jurkat T cells induces tyrosine phosphorylation of EphA3 receptors and cytoplasmic proteins, including the c-cbl proto-oncogene. Cbl phosphorylation was also observed in peripheral blood T cells. In contrast, stimulation of Jurkat cells with the EphB receptor ligand ephrin-B1 does not cause Cbl phosphorylation. EphA activation also induced Cbl association with Crk-L and Crk-II adapters, but not the related Grb2 protein. Induction of Cbl phosphorylation upon EphA activation appeared to be dependent upon Src family kinase activity, as Cbl phosphorylation was selectively abrogated by the Src family inhibitor 4-amino-5(4-chlorophenyl-7-(tert-butyl)pyrazolo[3,4-d]pyrimidine, while EphA phosphorylation was unimpaired. Ephrin-A1 stimulation of Jurkat cells was also found to cause down-regulation of endogenous EphA3 receptors from the cell surface and their degradation. In accordance with the role of Cbl as a negative regulator of receptor tyrosine kinases, overexpression of wild-type Cbl, but not its 70-Z mutant, was found to down-regulate EphA receptor expression. Receptor down-regulation could also be inhibited by blockage of Src family kinase activity. Our findings show that EphA receptors can actively signal in T cells, and that Cbl performs multiple roles in this signaling pathway, functioning to transduce signals from the receptors as well as regulating activated EphA receptor expression.
Hepatocyte NF-1 and STAT6 Cooperate with Additional DNA-Binding Factors to Activate Transcription of the Human Polymeric Ig Receptor Gene in Response to IL-4
Authors: Schjerven Hilde , Brandtzaeg Per , Johansen Finn-Eirik 
Published: April 2014

AbstractSecretory IgA and IgM, which protect the mucosal surfaces, are generated by selective transport of locally produced polymeric (p)Igs through the epithelial barrier by the pIgR. The expression of this receptor, and hence the generation of secretory Igs, is modulated by numerous extracellular factors. We have previously identified a STAT6 site in intron 1 of the human pIgR gene that is required for the slow and de novo protein synthesis-dependent IL-4-mediated transcriptional activation of the gene. In this study, we show that this intronic IL-4-responsive enhancer is confined to a 250-bp region that is highly conserved in the murine pIgR gene. The enhancer was dependent on the cooperation between the STAT6 site and at least four additional DNA elements. EMSA experiments demonstrated binding by hepatocyte NF-1 to one of these DNA elements. Extensive overlap in the tissue distribution of hepatocyte NF-1 and pIgR suggests that this transcription factor contributes to tissue-specific pIgR expression. Changing the helical phase between the STAT6 site and downstream DNA elements greatly reduced the strength of the IL-4 response, suggesting that the precise organization of this enhancer is important for its proper function. Thus, several transcription factors cooperate in this enhanceosome to mediate IL-4 responsiveness in HT-29 epithelial cells.
Characterization and Analysis of the Proximal Janus Kinase 3 Promoter
Authors: Aringer Martin , Hofmann Sigrun R. , Frucht David M. , Chen Min , Centola Michael , Morinobu Akio , Visconti Roberta , Kastner Daniel L. , Smolen Josef S. , O’Shea John J. 
Published: April 2014

Abstract
Janus kinase 3 (Jak3) is a nonreceptor tyrosine kinase essential for signaling via cytokine receptors that comprise the common γ-chain (γc), i.e., the receptors for IL-2, IL-4, IL-7, IL-9, IL-15, and IL-21. Jak3 is preferentially expressed in hemopoietic cells and is up-regulated upon cell differentiation and activation. Despite the importance of Jak3 in lymphoid development and immune function, the mechanisms that govern its expression have not been defined. To gain insight into this issue, we set out to characterize the Jak3 promoter. The 5′-untranslated region of the Jak3 gene is interrupted by a 3515-bp intron. Upstream of this intron and the transcription initiation site, we identified an ∼1-kb segment that exhibited lymphoid-specific promoter activity and was responsive to TCR signals. Truncation of this fragment revealed that core promoter activity resided in a 267-bp fragment that contains putative Sp-1, AP-1, Ets, Stat, and other binding sites. Mutation of the AP-1 sites significantly diminished, whereas mutation of the Ets sites abolished, the inducibility of the promoter construct. Chromatin immunoprecipitation assays showed that histone acetylation correlates with mRNA expression and that Ets-1/2 binds this region. Thus, transcription factors that bind these sites, especially Ets family members, are likely to be important regulators of Jak3 expression.
Spontaneous Clustering and Tyrosine Phosphorylation of NK Cell Inhibitory Receptor Induced by Ligand Binding
Authors: Faure Mathias , Barber Domingo F. , Takahashi Stephenie M. , Jin Tian , Long Eric O. 
Published: April 2014

AbstractInhibition of NK cell cytotoxicity by killer cell Ig-like receptors (KIR) depends on phosphorylation of cytoplasmic tyrosines in KIR, which recruit tyrosine phosphatase Src homology protein tyrosine phosphatase 1. It is not clear how KIR, whose function lies downstream of a tyrosine kinase, succeeds in blocking proximal NK cell activation signals upon binding HLA class I on target cells. Here we show that mixing NK cells with insect cells expressing HLA-C was sufficient to induce clustering of KIR, and phosphorylation of KIR and SHP-1. Transient phosphorylation of KIR was detected in the presence of pervanadate, an inhibitor of protein tyrosine phosphatases, at suboptimal concentration. Phosphorylation of KIR was specifically induced by ligand binding because it was detected only when HLA-C was loaded with a peptide that permits KIR binding. KIR phosphorylation was not dependent on ICAM-1-mediated adhesion and was not blocked by inhibition of actin polymerization, but required Zn2+. Fluorescence resonance energy transfer between HLA-C molecules revealed close molecular interactions induced by KIR binding. These results demonstrate tight clustering of KIR and rapid KIR phosphorylation induced simply by binding to HLA-C. The unique property of KIR to become phosphorylated in the absence of adhesion and of actin cytoskeleton rearrangement explains how KIR can efficiently block early activation signals during NK-target cell contacts.
Salmonella typhimurium Strains Carrying Independent Mutations Display Similar Virulence Phenotypes Yet Are Controlled by Distinct Host Defense Mechanisms
Authors: Raupach Bärbel , Kurth Nicole , Pfeffer Klaus , Kaufmann Stefan H. E. 
Published: April 2014

Abstract
The outcome of Salmonella infection in the mammalian host favors whoever succeeds best in disturbing the equilibrium between coordinate expression of bacterial (virulence) genes and host defense mechanisms. Intracellular persistence in host cells is critical for pathogenesis and disease, because Salmonella typhimurium strains defective in this property are avirulent. We examined whether similar host defense mechanisms are required for growth control of two S. typhimurium mutant strains. Salmonella pathogenicity island 2 (SPI2) and virulence plasmid-cured Salmonella mutants display similar virulence phenotypes in immunocompetent mice, yet their gene loci participate in independent virulence strategies. We determined the role of TNF-α and IFN-γ as well as different T cell populations in infection with these Salmonella strains. After systemic infection, IFN-γ was essential for growth restriction of plasmid-cured S. typhimurium, while SPI2 mutant infections were controlled in the absence of IFN-γ. TNFRp55-deficiency restored systemic virulence to both Salmonella mutants. After oral inoculation, control of plasmid-cured bacteria substantially relied on both IFN-γ and TNF-α signaling while control of SPI2 mutants did not. However, for both mutants, ultimate clearance of bacteria from infected mice depended on αβ T cells.
Overexpression of Toll-Like Receptor 4 Amplifies the Host Response to Lipopolysaccharide and Provides a Survival Advantage in Transgenic Mice
Authors: Bihl Franck , Salez Laurent , Beaubier Magali , Torres David , Larivière Line , Laroche Line , Benedetto Alexandre , Martel Dominic , Lapointe Jean-Martin , Ryffel Bernhard , Malo Danielle 
Published: April 2014

AbstractToll-like receptors are transmembrane proteins that are involved in the innate immune recognition of microbial constituents. Among them, Toll-like receptor 4 (Tlr4) is a crucial signal transducer for LPS, the major component of Gram-negative bacteria outer cell membrane. The contribution of Tlr4 to the host response to LPS and to infection with virulent Salmonella typhimurium was studied in four transgenic (Tg) strains including three overexpressing Tlr4. There was a good correlation between the level of Tlr4 mRNA expression and the sensitivity to LPS both in vitro and in vivo: Tg mice possessing the highest number of Tlr4 copies respond the most to LPS. Overexpression of Tlr4 by itself appears to have a survival advantage in Tg mice early during infection: animals possessing more than two copies of the gene survived longer and in a greater percentage to Salmonella infection. The beneficial effect of Tlr4 overexpression is greatly enhanced when the mice present a wild-type allele at natural resistance-associated macrophage protein 1, another critical innate immune gene involved in resistance to infection with Salmonella. Tlr4 and natural resistance-associated macrophage protein 1 exhibit functional epistatic interaction to improve the capacity of the host to control bacterial replication. However, this early improvement in disease resistance is not conducted later during infection, because mice overexpressing Tlr4 developed an excessive inflammatory response detrimental to the host.
The Autoreactivity of Anti-Phosphorylcholine Antibodies for Atherosclerosis-Associated Neo-Antigens and Apoptotic Cells
Authors: Shaw Peter X. , Goodyear Carl S. , Chang Mi-Kyung , Witztum Joseph L. , Silverman Gregg J. 
Published: April 2014

Abstract
Abs specific for phosphorylcholine (PC) are known to contribute to the immune defense against a variety of microbial infections. To assess for other types of binding interactions, we performed surveys of anti-PC Abs of diverse biologic origins and structural diversity and demonstrated a common autoreactivity for oxidatively modified low density lipoprotein and other oxidation-specific structures containing PC-Ags. We also found that cells undergoing apoptosis sequentially express a range of oxidation-specific neo-self PC determinants. Whereas natural Abs to PC recognized cells at early stages of apoptosis, by contrast, an IgG anti-PC Ab, representative of a T cell-dependent response, recognized PC determinants primarily associated with late stages of apoptosis. Cumulatively, these results demonstrate a fundamental paradigm in which Abs from both the innate and the T cell-dependent tiers of the B cell compartment recognize a minimal molecular motif arrayed both on microbes and as neo-self Ags linked to atherosclerosis and autoimmune disease.
Both Lymphotoxin-α and TNF Are Crucial for Control ofToxoplasma gondiiin the Central Nervous System
Authors: Schlüter Dirk , Kwok Lai-Yu , Lütjen Sonja , Soltek Sabine , Hoffmann Sigrid , Körner Heinrich , Deckert Martina 
Published: April 2014

AbstractImmunity to Toxoplasma gondii critically depends on TNFR type I-mediated immune reactions, but the precise role of the individual ligands of TNFR1, TNF and lymphotoxin-α (LTα), is still unknown. Upon oral infection with T. gondii, TNF−/−, LTα−/−, and TNF/LTα−/− mice failed to control intracerebral T. gondii and succumbed to an acute necrotizing Toxoplasma encephalitis, whereas wild-type (WT) mice survived. Intracerebral inducible NO synthase expression and–early after infection–splenic NO levels were reduced. Additionally, peritoneal macrophages produced reduced levels of NO upon infection with T. gondii and had significantly reduced toxoplasmastatic activity in TNF−/−, LTα−/−, and TNF/LTα−/− mice as compared with WT animals. Frequencies of parasite-specific IFN-γ-producing T cells, intracerebral and splenic IFN-γ production, and T. gondii-specific IgM and IgG titers in LTα−/− and TNF/LTα−/− mice were reduced only early after infection. In contrast, intracerebral IL-10 and IL-12p40 mRNA expression and splenic IL-2, IL-4, and IL-12 production were identical in all genotypes. In addition, TNF−/−, LTα−/−, and TNF/LTα−/−, but not WT, mice succumbed to infection with the highly attenuated ts-4 strain of T. gondii or to a subsequent challenge infection with virulent RH toxoplasms, although they had identical frequencies of IFN-γ-producing T cells as compared with WT mice. Generation and infection of bone marrow reconstitution chimeras demonstrated an exclusive role of hematogeneously produced TNF and LTα for survival of toxoplasmosis. These findings demonstrate the crucial role of both LTα and TNF for control of intracerebral toxoplasms.
Variations in Eosinophil Chemokine Responses: An Investigation of CCR1 and CCR3 Function, Expression in Atopy, and Identification of a Functional CCR1 Promoter
Authors: Phillips Rhian M. , Stubbs Victoria E. L. , Henson Mandy R. , Williams Timothy J. , Pease James E. , Sabroe Ian 
Published: April 2014

AbstractWe previously showed in a small group of donors that eosinophils from a subgroup of individuals responded equipotently to CC chemokine ligand (CCL)11/eotaxin and CCL3/macrophage-inflammatory protein-1α in assays of eosinophil shape change (CCL3/macrophage-inflammatory protein-1α-highly responsive (MHR) donors). In this study, we investigated the functional role of CCL3 in eosinophil responses in 73 donors. MHR donors, identified by their eosinophil shape change responses, represented ∼19% of the donor pool. Eosinophils from these donors showed increased eosinophil CCR1 expression and also underwent CCL3-mediated chemotaxis and up-regulation of CD11b. All MHR donors gave a history of atopy-associated diseases. In a further study, we prospectively recruited 110 subjects, subdivided into nonatopics or atopics, and investigated expression of CCR1 and CCR3 on eosinophils, basophils, monocytes, and neutrophils. Eosinophil CCR1 expression was non-normally distributed in atopics, although higher CCR1 expression levels were not predictive of a diagnosis of atopy or atopic disease. We identified the CCR1 promoter and investigated its function. We found a minimal promoter within 177 bp of the transcription start site, and an upstream enhancer region that facilitated expression in leukocyte cell lines. Collectively, these data demonstrate that MHR individuals form an important subgroup that, when associated with a diagnosis of allergic disease, may require tailored therapy to modulate eosinophil recruitment. Identification of a functional CCR1 promoter will facilitate the study of possible genetic determinants underlying this potentially important clinical phenotype.
Regulation of Chemokine mRNA Stability by Lipopolysaccharide and IL-10
Authors: Biswas Roopa , Datta Shyamasree , Gupta Jaydip Das , Novotny Michael , Tebo Julie , Hamilton Thomas A. 
Published: April 2014

AbstractIL-10 has been reported to inhibit the expression of LPS-induced proinflammatory cytokines and chemokines by altering the rate of specific mRNA decay although the molecular target(s) for its action remain unknown. In the present study, using primary peritoneal exudate macrophages and a cell culture model in which a tetracycline-responsive promoter controls transcription of CXC ligand 1 (KC) mRNA, we demonstrate that LPS promotes a time-dependent increase in KC mRNA stability. Although IL-10 had no direct effect on mRNA decay, this treatment antagonized the stabilizing action of LPS. The mechanisms involved were further explored using a cell-free mRNA degradation system. A 5′-capped, polyadenylated in vitro transcript derived from the 3′-untranslated region of KC mRNA exhibited time-dependent decay in the presence of protein extracts prepared from untreated RAW264.7 macrophages. Extracts prepared from LPS-treated RAW264.7 cells had reduced decay activity and this change was antagonized if the cells were costimulated with IL-10. A substrate in which the AU-rich element motifs were mutated exhibited minimal decay that did not vary using extracts prepared from cells treated with LPS or LPS and IL-10. A nonadenylated RNA substrate was also degraded and that activity was diminished by LPS. In concert, these findings demonstrate that KC mRNA stability is regulated by LPS-induced alterations in activities that govern both deadenylation and degradation of the mRNA body. The effects of IL-10 on KC mRNA stability reflect antagonism of the response to LPS.