bluuebunny/crossref_metadata_2025_split huggingface dataset:
Microarray Analysis of Lyn-Deficient B Cells Reveals Germinal Center-Associated Nuclear Protein and Other Genes Associated with the Lymphoid Germinal Center
Authors: Mirnics Zeljka Korade , Caudell Eva , Gao YanHua , Kuwahara Kazuhiko , Sakaguchi Nobuo , Kurosaki Tomohiro , Burnside Joan , Mirnics Károly , Corey Seth J. 
Published: April 2014

Abstract
Lyn is the only member of the Src family expressed in DT40 B cells, which provide a unique model to study the singular contribution of this protein tyrosine kinase (PTK) family to cell signaling. In these cells, gene ablation of Lyn leads to defective B cell receptor signaling. Complementary DNA array analysis of Lyn-deficient DT40 cells shows that the absence of Lyn leads to down-regulation of numerous genes encoding proteins involved in B cell receptor signaling, proliferation, control of transcription, immunity/inflammation response, and cytoskeletal organization. Most of these expression changes have not been previously associated with Lyn PTK signaling. They include alterations in mRNA levels of germinal center-associated nuclear protein (germinal center-associated DNA primase) (GANP), CD74, CD22, NF-κB, elongation factor 1α, CD79b, octamer binding factor 1, Ig H chain, stathmin, and γ-actin. Changes in GANP expression were also confirmed in Lyn-deficient mice, suggesting that Lyn PTK has a unique function not compensated for by other Src kinases. Because Lyn-deficient mice have impaired development of germinal centers in spleen, the decreased expression of GANP in the Lyn-deficient DT40 cell line and Lyn-deficient mice suggests that Lyn controls the formation and proliferation of germinal centers via GANP. GANP promoter activity was higher in wild-type vs Lyn-deficient cells. Mutation of the PU.1 binding site reduced activity in wild-type cells and had no effect in Lyn-deficient cells. The presence of Lyn enhanced PU.1 expression in a Northern blot. Thus, the following new signaling pathway has been described: Lyn→PU.1→GANP.
Effect of Decreasing the Affinity of the Class II-Associated Invariant Chain Peptide on the MHC Class II Peptide Repertoire in the Presence or Absence of H-2M1
Authors: Honey Karen , Forbush Katherine , Jensen Peter E. , Rudensky Alexander Y. 
Published: April 2014

Abstract
The class II-associated invariant chain peptide (CLIP) region of the invariant chain (Ii) directly influences MHC class II presentation by occupying the MHC class II peptide-binding groove, thereby preventing premature loading of peptides. Different MHC class II alleles exhibit distinct affinities for CLIP, and a low affinity interaction has been associated with decreased dependence upon H-2M and increased susceptibility to rheumatoid arthritis, suggesting that decreased CLIP affinity alters the MHC class II-bound peptide repertoire, thereby promoting autoimmunity. To examine the role of CLIP affinity in determining the MHC class II peptide repertoire, we generated transgenic mice expressing either wild-type human Ii or human Ii containing a CLIP region of low affinity for MHC class II. Our data indicate that although degradation intermediates of Ii containing a CLIP region with decreased affinity for MHC class II do not remain associated with I-Ab, this does not substantially alter the peptide repertoire bound by MHC class II or increase autoimmune susceptibility in the mice. This implies that the affinity of the CLIP:MHC class II interaction is not a strong contributory factor in determining the probability of developing autoimmunity. In contrast, in the absence of H-2M, MHC class II peptide repertoire diversity is enhanced by decreasing the affinity of CLIP for MHC class II, although MHC class II cell surface expression is reduced. Thus, we show clearly, in vivo, the critical chaperone function of H-2M, which preserves MHC class II molecules for high affinity peptide binding upon dissociation of Ii degradation intermediates.
Glucose-Regulated Protein 94/Glycoprotein 96 Elicits Bystander Activation of CD4+ T Cell Th1 Cytokine Production In Vivo
Authors: Baker-LePain Julie C. , Sarzotti Marcella , Nicchitta Christopher V. 
Published: April 2014

Abstract
Glucose-regulated protein 94 (GRP94/gp96), the endoplasmic reticulum heat shock protein 90 paralog, elicits both innate and adaptive immune responses. Regarding the former, GRP94/gp96 stimulates APC cytokine expression and dendritic cell maturation. The adaptive component of GRP94/gp96 function reflects a proposed peptide-binding activity and, consequently, a role for native GRP94/gp96-peptide complexes in cross-presentation. It is by this mechanism that tumor-derived GRP94/gp96 is thought to suppress tumor growth and metastasis. Recent data have demonstrated that GRP94/gp96-elicited innate immune responses can be sufficient to suppress tumor growth and metastasis. However, the immunological processes activated in response to tumor Ag-negative sources of GRP94/gp96 are currently unknown. We have examined the in vivo immunological response to nontumor sources of GRP94/gp96 and report that administration of syngeneic GRP94/gp96- or GRP94/gp96-N-terminal domain-secreting KBALB fibroblasts to BALB/c mice stimulates CD11b+ and CD11c+ APC function and promotes bystander activation of CD4+ T cell Th1 cytokine production. Only modest activation of CD8+ T cell or NK cell cytolytic function was observed. The GRP94/gp96-dependent induction of CD4+ T cell cytokine production was markedly inhibited by carrageenan, indicating an essential role for APC in this response. These results identify the bystander activation of CD4+ T lymphocytes as a previously unappreciated immunological consequence of GRP94/gp96 administration and demonstrate that GRP94/gp96-elicited alterations in the in vivo cytokine environment influence the development of CD4+ T cell effector functions, independently of its proposed function as a peptide chaperone.
Maintenance, Loss, and Resurgence of T Cell Responses During Acute, Protracted, and Chronic Viral Infections
Authors: Fuller Michael J. , Khanolkar Aaruni , Tebo Anne E. , Zajac Allan J. 
Published: April 2014

AbstractThe acute phase of many viral infections is associated with the induction of a pronounced CD8 T cell response which plays a principle role in clearing the infection. By contrast, certain infections are not as readily controlled. In this study, we have used the well-defined system of lymphocytic choriomeningitis virus (LCMV) infection of mice to determine quantitative and qualitative changes in virus-specific CD8 T cell responses that rapidly resolve acute infections, more slowly control protracted infections, or fail to clear chronic infections. Acute LCMV infection elicits potent, functional, multi-epitope-specific CD8 T cell responses. Virus-specific CD8 T cells also expand, albeit to a lesser extent, during protracted LCMV infection. Under these conditions, there is a progressive diminution in the capacity to produce IL-2, TNF-α, and IFN-γ. Changes in cytotoxic activities are also detectable but differ depending upon the specificity of the responding cells. As the infection is slowly resolved, a resurgence of cytokine production by virus-specific CD8 T cells is observed. CD4-deficient mice cannot control infection with certain strains of LCMV, but do mount multi-epitope-specific CD8 T cell responses that also lose effector capabilities; however, they are not maintained indefinitely in an unresponsive state as these cells become deleted over time. Overall, our findings suggest that constant high viral loads result in the progressive diminution of T cell effector functions and subsequent physical loss of the responding cells, whereas if the viral load is brought under control a partial restoration of CD8 T cell functions can occur.
Defining Th1 and Th2 Immune Responses in a Reciprocal Cytokine Environment In Vivo
Authors: Chitnis Tanuja , Salama Alan D. , Grusby Michael J. , Sayegh Mohamed H. , Khoury Samia J. 
Published: April 2014

Abstract
The ability of committed Th1 and Th2 cells to function in altered cytokine environments is a central issue in autoimmune and immune-mediated diseases. Therefore, it is of interest to study the ability of Th1 or Th2 cells to expand and produce cytokine reciprocal environments in vivo. Using STAT4- and STAT6-deficient mice, we studied the expansion and cytokine production of Ag-specific Th1 or Th2 cells after transfer into Th1, Th2, or wild-type recipients. Our data show that these Th1 or Th2 cells proliferated and clonally expanded normally, regardless of the in vivo cytokine environment. These data have implications for the treatment of immune-mediated diseases by immunomodulatory agents that alter the cytokine milieu in vivo.
Recombinogenic Phenotype of Human Activation-Induced Cytosine Deaminase
Authors: Poltoratsky Vladimir P. , Wilson Samuel H. , Kunkel Thomas A. , Pavlov Youri I. 
Published: April 2014

Abstract
Class switch recombination, gene conversion, and somatic hypermutation that diversify rearranged Ig genes to produce various classes of high affinity Abs are dependent on the enzyme activation-induced cytosine deaminase (AID). Evidence suggests that somatic hypermutation is due to error-prone DNA repair that is initiated by AID-mediated deamination of cytosine in DNA, whereas the mechanism by which AID controls recombination remains to be elucidated. In this study, using a yeast model system, we have observed AID-dependent recombination. Expression of human AID in wild-type yeast is mutagenic for G-C to A-T transitions, and as expected, this mutagenesis is increased upon inactivation of uracil-DNA glycosylase. AID expression also strongly induces intragenic mitotic recombination, but only in a strain possessing uracil-DNA glycosylase. Thus, the initial step of base excision repair is required for AID-dependent recombination and is a branch point for either hypermutagenesis or recombination.
Depletion of Cellular Cholesterol and Lipid Rafts Increases Shedding of CD30
Authors: von Tresckow Bastian , Kallen Karl-Josef , von Strandmann Elke Pogge , Borchmann Peter , Lange Hans , Engert Andreas , Hansen Hinrich P. 
Published: April 2014

Abstract
CD30, a lymphoid activation marker, is shed into the cell environment after endoproteolytic cleavage of its ectodomain. Soluble (s)CD30 is able to suppress the Th1-type immune response. Because high serum levels of sCD30 and cholesterol-lowering drugs seem to be beneficial in some Th1-type autoimmune diseases, we focused on a link between CD30 shedding and the amount of cellular cholesterol. Cholesterol depletion of human Hodgkin lymphoma- and non-Hodgkin lymphoma-derived cell lines by methyl-β-cyclodextrin led to a down-regulation of membrane-bound CD30 and increased release of sCD30. Additionally, the cholesterol-interfering drugs lovastatin, cholesterol oxidase, and filipin increased CD30 shedding. Both the down-regulation of membrane-anchored CD30 and the release of sCD30 were dependent on metalloproteinases. Using specific inhibitors, we detected TNF-α converting enzyme (TACE) as the leading enzyme responsible for cholesterol-dependent CD30 shedding. A Triton X-100-based method for lipid raft isolation revealed that CD30 was partially present in lipid rafts, whereas TACE was localized in the nonraft fractions. Disintegration of lipid rafts by cholesterol depletion might therefore lead to dynamic interactions of CD30 with TACE, resulting in enhanced shedding of CD30. Our results suggest a possible role of cholesterol-dependent shedding of CD30 in the pathogenesis of immune diseases.
TNF and Phorbol Esters Induce Lymphotoxin-β Expression through Distinct Pathways Involving Ets and NF-κB Family Members
Authors: Voon Dominic C. , Subrata Lily S. , Karimi Mahdad , Ulgiati Daniela , Abraham Lawrence J. 
Published: April 2014

AbstractLymphotoxin-β (LT-β) is a transmembrane protein expressed mainly on cells of the lymphoid lineage. It associates with LT-α on the cell surface to form the heterotrimeric LTα1,β2 complex, which binds the LT-β receptor. Membrane lymphotoxin is a crucial signal for the appropriate development of lymph nodes and Peyer’s patches, and in the formation of B and T cell compartments in the spleen. In this study we report the characterization of mechanisms governing both basal as well as PMA- and TNF-inducible regulation of the human LT-β promoter. Using a Jurkat T cell line, induction with either PMA or TNF resulted in an increase in mRNA levels compared with uninduced values. This induction corresponded to an increase in transcriptional activity of the human LT-β promoter. Mutational and deletion analysis demonstrated the importance of Ets and NF-κB motifs in the regulation of basal transcription. Furthermore, the ability of PMA to induce activity was lost in the Ets mutant constructs. Interestingly, the same mutation had little effect on the ability of TNF to induce transcription of the LT-β promoter. TNF inducibility was localized to the NF-κB site positioned at −83 of the promoter sequence. Thus, it appears that the Ets site, although playing a major role in PMA induction, did not mediate TNF inducibility. Therefore, our study suggests that alternative signaling pathways may be present to induce the expression of LT-β in response to different immunological or inflammatory stimuli.
Cloning, Expression, Cellular Distribution, and Role in Chemotaxis of a C5a Receptor in Rainbow Trout: The First Identification of a C5a Receptor in a Nonmammalian Species
Authors: Boshra Hani , Li Jun , Peters Rodney , Hansen John , Matlapudi Anjan , Sunyer J. Oriol 
Published: April 2014

Abstract
C3a, C4a, and C5a anaphylatoxins generated during complement activation play a key role in inflammation. C5a is the most potent of the three anaphylatoxins in eliciting biological responses. The effects of C5a are mediated by its binding to C5a receptor (C5aR, CD88). To date, C5aR has only been identified and cloned in mammalian species, and its evolutionary history remains ill-defined. To gain insights into the evolution, conserved structural domains, and functions of C5aR, we have cloned and characterized a C5aR in rainbow trout, a teleost fish. The isolated cDNA encoded a 350-aa protein that showed the highest sequence similarity to C5aR from other species. Genomic analysis revealed the presence of one continuous exon encoding the entire open reading frame. Northern blot analysis showed significant expression of the trout C5a receptor (TC5aR) message in PBLs and kidney. Flow cytometric analysis showed that two Abs generated against two different areas of the extracellular N-terminal region of TC5aR positively stained the same leukocyte populations from PBLs. B lymphocytes and granulocytes comprised the majority of cells recognized by the anti-TC5aR. More importantly, these Abs inhibited chemotaxis of PBLs toward a chemoattractant fraction purified from complement-activated trout serum. Our data suggest that the split between C5aR and C3aR from a common ancestral molecule occurred before the emergence of teleost fish. Moreover, we demonstrate that the overall structure of C5aR as well as its role in chemotaxis have remained conserved for &gt;300 million years.
Signaling through Toll-Like Receptors Triggers HIV-1 Replication in Latently Infected Mast Cells
Authors: Sundstrom J. Bruce , Little Dawn M. , Villinger Francois , Ellis Jane E. , Ansari Aftab A. 
Published: April 2014

Abstract
Evidence that human progenitor mast cells are susceptible to infection with CCR5-tropic strains of HIV-1 and that circulating HIV-1-infected FcεRIα+ cells with a similar progenitor phenotype have been isolated from AIDS patients has led to speculation that mast cells may serve as a potential reservoir for infectious HIV-1. In this study, progenitor mast cells, developed in vitro from CD34+ cord blood stem cells, were experimentally infected with the CCR5-tropic strain HIV-1Bal after 28 days in culture as they reached their HIV-1-susceptible progenitor stage. HIV-1 p24 Ag levels were readily detectable by day 7 postinfection (PI), peaked at 2–3 wk PI as mature (tryptase/chymase-positive) HIV-1 infection-resistant mast cells emerged, and then steadily declined to below detectable limits by 10 wk PI, at which point integrated HIV-1 proviral DNA was confirmed by PCR quantitation in (∼34% of) latently infected mast cells. Stimulation by ligands for Toll-like receptor (TLR) 2, TLR4, or TLR9 significantly enhanced viral replication in a dose- and time-dependent manner in both HIV-1-infected progenitor and latently infected mature mast cells, without promoting degranulation, apoptosis, cellular proliferation, or dysregulation of TLR agonist-induced cytokine production in infected mast cells. Limiting dilution analysis of TLR activated, latently infected mature mast cells indicated that one in four was capable of establishing productive infections in A301 sentinel cells. Taken together, these results indicate that mast cells may serve both as a viral reservoir and as a model for studying mechanisms of postintegration latency in HIV infection.
Subpopulations of Mouse Blood Monocytes Differ in Maturation Stage and Inflammatory Response
Authors: Sunderkötter Cord , Nikolic Tatjana , Dillon Marilyn J. , van Rooijen Nico , Stehling Martin , Drevets Douglas A. , Leenen Pieter J. M. 
Published: April 2014

Abstract
Blood monocytes are well-characterized precursors for macrophages and dendritic cells. Subsets of human monocytes with differential representation in various disease states are well known. In contrast, mouse monocyte subsets have been characterized minimally. In this study we identify three subpopulations of mouse monocytes that can be distinguished by differential expression of Ly-6C, CD43, CD11c, MBR, and CD62L. The subsets share the characteristics of extensive phagocytosis, similar expression of M-CSF receptor (CD115), and development into macrophages upon M-CSF stimulation. By eliminating blood monocytes with dichloromethylene-bisphosphonate-loaded liposomes and monitoring their repopulation, we showed a developmental relationship between the subsets. Monocytes were maximally depleted 18 h after liposome application and subsequently reappeared in the circulation. These cells were exclusively of the Ly-6Chigh subset, resembling bone marrow monocytes. Serial flow cytometric analyses of newly released Ly-6Chigh monocytes showed that Ly-6C expression on these cells was down-regulated while in circulation. Under inflammatory conditions elicited either by acute infection with Listeria monocytogenes or chronic infection with Leishmania major, there was a significant increase in immature Ly-6Chigh monocytes, resembling the inflammatory left shift of granulocytes. In addition, acute peritoneal inflammation recruited preferentially Ly-6Cmed-high monocytes. Taken together, these data identify distinct subpopulations of mouse blood monocytes that differ in maturation stage and capacity to become recruited to inflammatory sites.
HIV-Specific CD8+ T Cells Exhibit Markedly Reduced Levels of Bcl-2 and Bcl-xL
Authors: Petrovas Constantinos , Mueller Yvonne M. , Dimitriou Ioannis D. , Bojczuk Paul M. , Mounzer Karam C. , Witek James , Altman John D. , Katsikis Peter D. 
Published: April 2014

AbstractHuman immunodeficiency virus-specific CD8+ T cells are highly sensitive to spontaneous and CD95/Fas-induced apoptosis, and this sensitivity may impair their ability to control HIV infection. To elucidate the mechanism behind this sensitivity, in this study we examined the levels of antiapoptotic molecules Bcl-2 and Bcl-xL in HIV-specific CD8+ T cells from HIV-infected individuals. Bcl-2 expression was markedly decreased in HIV-specific CD8+ T cells compared with CMV-specific and total CD8+ T cells from HIV-infected individuals as well as total CD8+ T cells from healthy donors. CD8+ T cell Bcl-2 levels inversely correlated with spontaneous and CD95/Fas-induced apoptosis of CD8+ T cells from HIV-infected individuals. HIV-specific CD8+ T cells also had significantly lower levels of Bcl-xL compared with CMV-specific CD8+ T cells. Finally, IL-15 induces both Bcl-2 and Bcl-xL expression in HIV-specific and total CD8+ T cells, and this correlated with apoptosis inhibition and increased survival in both short- and long-term cultures. Our data indicate that reduced Bcl-2 and Bcl-xL may play an important role in the increased sensitivity to apoptosis of HIV-specific CD8+ T cells and suggest a possible mechanism by which IL-15 increases their survival.
Macrophage Interactions with Neutrophils RegulateLeishmania majorInfection
Authors: Ribeiro-Gomes Flávia L. , Otero Ana C. , Gomes Nitza A. , Moniz-de-Souza Maria Carolina A. , Cysne-Finkelstein Lea , Arnholdt Andrea C. , Calich Vera L. , Coutinho Sergio G. , Lopes Marcela F. , DosReis George A. 
Published: April 2014

AbstractMacrophages are host cells for the pathogenic parasite Leishmania major. Neutrophils die and are ingested by macrophages in the tissues. We investigated the role of macrophage interactions with inflammatory neutrophils in control of L. major infection. Coculture of dead exudate neutrophils exacerbated parasite growth in infected macrophages from susceptible BALB, but killed intracellular L. major in resistant B6 mice. Coinjection of dead neutrophils amplified L. major replication in vivo in BALB, but prevented parasite growth in B6 mice. Neutrophil depletion reduced parasite load in infected BALB, but exacerbated infection in B6 mice. Exacerbated growth of L. major required PGE2 and TGF-β production by macrophages, while parasite killing depended on neutrophil elastase and TNF-α production. These results indicate that macrophage interactions with dead neutrophils play a previously unrecognized role in host responses to L. major infection.
O-Methylated Catechins from Tea Leaves Inhibit Multiple Protein Kinases in Mast Cells
Authors: Maeda-Yamamoto Mari , Inagaki Naoki , Kitaura Jiro , Chikumoto Takao , Kawahara Hiroharu , Kawakami Yuko , Sano Mitsuaki , Miyase Toshio , Tachibana Hirofumi , Nagai Hiroichi , Kawakami Toshiaki 
Published: April 2014

Abstract
Tea contains a variety of bioactive compounds. In this study, we show that two O-methylated catechins, (-)-epigallocatechin-3-O-(3-O-methyl) gallate and (-)-epigallocatechin-3-O-(4-O-methyl) gallate, inhibit in vivo mast cell-dependent allergic reactions more potently than their nonmethylated form, (-)-epigallocatechin-3-O-gallate. Consistent with this, these O-methylated catechins inhibit IgE/Ag-induced activation of mouse mast cells: histamine release, leukotriene release, and cytokine production and secretion were all inhibited. As a molecular basis for the catechin-mediated inhibition of mast cell activation, Lyn, Syk, and Bruton’s tyrosine kinase, the protein tyrosine kinases, known to be critical for early activation events, are shown to be inhibited by the O-methylated catechins. In vitro kinase assays using purified proteins show that the O-methylated catechins can directly inhibit the above protein tyrosine kinases. These catechins inhibit IgE/Ag-induced calcium response as well as the activation of downstream serine/threonine kinases such as Akt and c-Jun N-terminal kinase. These observations for the first time have revealed the molecular mechanisms of antiallergic effects of tea-derived catechins.