bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enhanced Th1 Response toStaphylococcus aureusInfection in Human Lactoferrin-Transgenic Mice
Authors: Guillén Cristina , McInnes Iain B. , Vaughan Diane M. , Kommajosyula Sharada , Van Berkel Patrick H. C. , Leung Bernard P. , Aguila Antonio , Brock Jeremy H. 
Published: April 2014

AbstractLactoferrin (Lf) is an iron-binding protein of external secretions and neutrophil secondary granules with antimicrobial and immunomodulatory activities. To further define these properties of Lf, we have investigated the response to Staphylococcus aureus infection in transgenic mice carrying a functional human Lf gene. The transgenic mice cleared bacteria significantly better than congenic littermates, associated with a trend to reduced incidence of arthritis, septicemia, and mortality. We identified two pathways by which S. aureus clearance was enhanced. First, human Lf directly inhibited the growth of S. aureus LS-1 in vitro. Second, S. aureus-infected transgenic mice exhibited enhanced Th1 immune polarization. Thus, spleen cells from infected transgenic mice produced higher levels of TNF-α and IFN-γ and less IL-5 and IL-10 upon stimulation ex vivo with the exotoxin toxic shock syndrome toxin-1 compared with congenic controls. To confirm that these effects of Lf transgene expression could occur in the absence of live bacterial infection, we also showed that Lf-transgenic DBA/1 mice exhibited enhanced severity of collagen-induced arthritis, an established model of Th1-induced articular inflammation. Higher levels of stainable iron in the spleens of transgenic mice correlated with human Lf distribution, but all other parameters of iron metabolism did not differ between transgenic mice and wild-type littermates. These results demonstrate that human Lf can mediate both antimicrobial and immunomodulatory activities with downstream effects on the outcome of immune pathology in infectious and inflammatory disease.
Antibody-Mediated Control of Persistent γ-Herpesvirus Infection
Authors: Kim In-Jeong , Flaño Emilio , Woodland David L. , Blackman Marcia A. 
Published: April 2014

AbstractThe human γ-herpesviruses, EBV and Kaposi’s sarcoma-associated herpesvirus, establish life-long latency and can reactivate in immunocompromised individuals. T cells play an important role in controlling persistent EBV infection, whereas a role for humoral immunity is less clear. The murine γ-herpesvirus-68 has biological and structural similarities to the human γ-herpesviruses, and provides an important in vivo experimental model for dissecting mechanisms of immune control. In the current studies, CD28−/− mice were used to address the role of Abs in control of persistent murine γ-herpesvirus-68 infection. Lytic infection was controlled in the lungs of CD28−/− mice, and latency was maintained in B cells at normal frequencies. Although class-switched virus-specific Abs were initially generated in the absence of germinal centers, titers and viral neutralizing activity rapidly waned. T cell depletion in CD28−/− mice with compromised Ab responses, but not in control mice with intact Ab responses, resulted in significant recrudescence from latency, both in the spleen and the lung. Recrudescence could be prevented by passive transfer of immune serum. These data directly demonstrate an important contribution of humoral immunity to control of γ-herpesvirus latency, and have significant implications for clinical intervention.
Trypanosoma cruziInfection Selectively Renders Parasite-Specific IgG+ B Lymphocytes Susceptible to Fas/Fas Ligand-Mediated Fratricide
Authors: Zuñiga Elina , Motran Claudia C. , Montes Carolina L. , Yagita Hideo , Gruppi Adriana 
Published: April 2014

AbstractThe control of B cell expansion has been thought to be solely regulated by T lymphocytes. We show in this study that Trypanosoma cruzi infection induces up-regulation of both Fas and Fas ligand (FasL) molecules on B cells and renders them susceptible to B cell-B cell killing (referred to as fratricide throughout this paper) mediated via Fas/FasL. Moreover, by in vivo administration of anti-FasL blocking mAb we demonstrate that Fas-mediated B cell apoptosis is an ongoing process during this parasitic infection. We also provide evidence that B cells that have switched to IgG isotype are the preferential targets of B cell fratricide. More strikingly, this death pathway selectively affects IgG+ B cells reactive to parasite but not self Ags. Parasite-specific but not self-reactive B cells triggered during this response are rescued after either in vitro or in vivo FasL blockade. Fratricide among parasite-specific IgG+ B lymphocytes could impair the immune control of T. cruzi and possibly other chronic protozoan parasites. Our results raise the possibility that the blockade of Fas/FasL interaction in the B cell compartment of T. cruzi-infected mice may provide a means for enhancing antiparasitic humoral immune response without affecting host tolerance.
Role of NADPH Oxidase in the Mechanism of Lung Neutrophil Sequestration and Microvessel Injury Induced by Gram-Negative Sepsis: Studies in p47phox−/− and gp91phox−/− Mice
Authors: Gao Xiao-pei , Standiford Thedodore J. , Rahman Arshad , Newstead Michael , Holland Steven M. , Dinauer Mary C. , Liu Qing-hui , Malik Asrar B. 
Published: April 2014

AbstractWe addressed the role of O⨪2 generated by the NADPH oxidase complex in the mechanism of polymorphonuclear leukocyte (PMN) accumulation and transalveolar migration and lung microvascular injury. Studies were made in mice lacking the p47phox and gp91phox subunits of NADPH oxidase (p47phox−/− and gp91phox−/−) in which PMN are incapable of the respiratory burst. The mice were challenged i.p. with live Escherichia coli to induce sepsis. We observed time-dependent increases in PMN sequestration and migration from 1 to 6 h after challenge with 2 × 108 E. coli. The responses in knockout mice were greater post-E. coli challenge compared with control mice; i.e., transalveolar PMN migration post-E. coli challenge increased by ∼50% in the null mice above values in wild type. The increased PMN infiltration was associated with decreased lung bacterial clearance. The generation of the chemoattractant macrophage-inflammatory protein-2 in lung tissue was greater in NADPH oxidase-defective mice after E. coli challenge than control mice; moreover, macrophage-inflammatory protein-2 Ab pretreatment prevented the PMN infiltration. We also observed that E. coli failed to increase lung microvascular permeability in p47phox−/− and gp91phox−/− mice despite the greater lung PMN sequestration. Thus, O⨪2 production is required for the induction of sepsis-induced lung microvascular injury. We conclude that NADPH oxidase-derived O⨪2 generation has an important bactericidal role, such that an impairment in bacterial clearance in NADPH oxidase-defective mice results in increased chemokine generation and lung tissue PMN infiltration.
CD8+ T Cells Are Required for Primary Immunity in C57BL/6 Mice Following Low-Dose, Intradermal Challenge withLeishmania major
Authors: Belkaid Yasmine , Von Stebut Esther , Mendez Susana , Lira Rosalia , Caler Elisabet , Bertholet Sylvie , Udey Mark C. , Sacks David 
Published: April 2014

AbstractStandard murine models of cutaneous leishmaniasis, involving s.c. inoculation of large numbers of Leishmania major promastigotes, have not supported an essential role for CD8+ T cells in the control of primary infection. Recently, a L. major model combining two main features of natural transmission, low parasite dose and inoculation into a dermal site, has been established in resistant C57BL/6 mice. In the present studies, C57BL/6 mice with CD8+ T cell deficiencies, including CD8−/− and CD8-depleted mice, failed to control the growth of L. major following inoculation of 100 metacyclic promastigotes into the ear dermis. The resulting dermal pathology was minor and delayed. Lesion formation in wild-type mice was coincident with the killing of parasites in the inoculation site. Both events were associated with the accumulation of CD8+ T lymphocytes in the skin and with the capacity of CD8+ T cells recovered from draining lymph nodes or infected dermis to release IFN-γ following coculture with infected dendritic cells. Reconstitution of resistance to L. major in RAG−/− mice using T cells from naive donors was optimal when both CD4+ and CD8+ T cells were transferred. Primed CD8+ T lymphocytes obtained from C57BL/6 mice during the acute stage of infection were able to mediate both pathology and immunity when transferred alone. The low dose, intradermal challenge model reveals that CD8+ T cells play an essential role in both pathogenesis of and immunity to primary infection with L. major in the skin.
C/EBPβGene Inactivation Causes Both Impaired and Enhanced Gene Expression and Inverse Regulation of IL-12 p40 and p35 mRNAs in Macrophages
Authors: Gorgoni Barbara , Maritano Diego , Marthyn Paola , Righi Marco , Poli Valeria 
Published: April 2014

AbstractThe transcription factor C/EBPβ is believed to play a fundamental role in regulating activated macrophage functions. However, the molecular mechanisms and the target genes involved have been, so far, poorly characterized, partly due to the difficulty of reproducibly obtaining homogeneous and abundant primary macrophage populations. In this study, we describe the generation and characterization of immortalized macrophage-like cell lines from C/EBPβ-deficient and wild-type mice. Using these cells, we were able to identify a number of genes involved in activated macrophage functions whose induction was affected in the C/EBPβ−/− cells. IFN-γ/LPS-dependent induction of IL-6, IL-1β, TNF-α, inducible NO synthase, and plasminogen activator inhibitor-1 mRNAs was variably impaired, while IL-12 p40, RANTES and macrophage inflammatory protein-1β mRNAs were up-regulated in the absence of C/EBPβ. The differential mRNA expression correlated with differential transcription levels of the corresponding genes, and was in most cases confirmed in primary macrophage populations. Moreover, in sharp contrast to the enhanced induction of IL-12 p40 mRNA, C/EBPβ−/− primary macrophages derived from both the bone marrow and the peritoneal cavity displayed totally defective expression of IL-12 p35 mRNA. Therefore, the IL-12 p35 gene represents a novel obligatory target for C/EBPβ in macrophages and this may explain the defective production of bioactive IL-12 and the impaired Th1 responses of C/EBPβ-deficient mice to Candida albicans infection observed in previous work.
Store-Operated Calcium Entry in Human Neutrophils Reflects Multiple Contributions from Independently Regulated Pathways
Authors: Itagaki Kiyoshi , Kannan K. B. , Livingston David H. , Deitch Edwin A. , Fekete Zoltan , Hauser Carl J. 
Published: April 2014

Abstract
Human polymorphonuclear neutrophil (PMN) responses to G protein-coupled chemoattractants are highly dependent upon store-operated Ca2+ entry (SOCE). Recent research suggests that SOCE currents can be mediated by a variety of related channel proteins of the transient receptor potential superfamily. SOCE has been regarded as a specific response to depletion of cell calcium stores. We hypothesized that net SOCE might reflect the contributions of more than one calcium entry pathway. SOCE was studied in normal human PMN using Ca2+ and Sr2+ ions. We found that PMN SOCE depends on at least two divalent cation influx pathways. One of these was nonspecific and Sr2+ permeable; the other was Ca2+ specific. The two pathways show different degrees of dependence on store depletion by thapsigargin and ionomycin, and differential sensitivity to inhibition by 2-aminoethyoxydiphenyl borane and gadolinium. The inflammatory G protein-coupled chemoattractants fMLP, platelet-activating factor, and IL-8 elicit unique patterns of Sr2+ and Ca2+ influx channel activation, and SOCE responses to these agonists displayed differing degrees of linkage to prior Ca2+ store depletion. The mechanisms of PMN SOCE responses to G protein-coupled chemoattractants are physiologically diverse. They appear to reflect Ca2+ transport through a variety of channels that are independently regulated to varying degrees by store depletion and by G protein-coupled receptor activation.
Regulation of the Mannan-Binding Lectin Pathway of Complement on Neisseria gonorrhoeae by C1-Inhibitor and α2-Macroglobulin
Authors: Gulati Sunita , Sastry Kedarnath , Jensenius Jens C. , Rice Peter A. , Ram Sanjay 
Published: April 2014

Abstract
We examined complement activation by Neisseria gonorrhoeae via the mannan-binding lectin (MBL) pathway in normal human serum. Maximal binding of MBL complexed with MBL-associated serine proteases (MASPs) to N. gonorrhoeae was achieved at a concentration of 0.3 μg/ml. Preopsonization with MBL-MASP at concentrations as low as 0.03 μg/ml resulted in ∼60% killing of otherwise fully serum-resistant gonococci. However, MBL-depleted serum (MBLdS) reconstituted with MBL-MASP before incubation with organisms (postopsonization) failed to kill at a 100-fold higher concentration. Preopsonized organisms showed a 1.5-fold increase in C4, a 2.5-fold increase in C3b, and an ∼25-fold increase in factor Bb binding; enhanced C3b and factor Bb binding was classical pathway dependent. Preopsonization of bacteria with a mixture of pure C1-inhibitor and/or α2-macroglobulin added together with MBL-MASP, all at physiologic concentrations before adding MBLdS, totally reversed killing in 10% reconstituted serum. Reconstitution of MBLdS with supraphysiologic (24 μg/ml) concentrations of MBL-MASP partially overcame the effects of inhibitors (57% killing in 10% reconstituted serum). We also examined the effect of sialylation of gonococcal lipooligosaccharide (LOS) on MBL function. Partial sialylation of LOS did not decrease MBL or C4 binding but did decrease C3b binding by 50% and resulted in 80% survival in 10% serum (lacking bacteria-specific Abs) even when sialylated organisms were preopsonized with MBL. Full sialylation of LOS abolished MBL, C4, and C3b binding, resulting in 100% survival. Our studies indicate that MBL does not participate in complement activation on N. gonorrhoeae in the presence of “complete” serum that contains C1-inhibitor and α2-macroglobulin.
Restricted Localization of the TNF Receptor CD120a to Lipid Rafts: A Novel Role for the Death Domain
Authors: Cottin Vincent , Doan Joyce E. S. , Riches David W. H. 
Published: April 2014

AbstractThe TNF-α receptor, CD120a, has recently been shown to be localized to both plasma membrane lipid rafts and to the trans Golgi complex. Through a combination of both confocal microscopy and sucrose density gradient ultracentrifugation, we show that amino acid sequences located within the death domain (DD) of CD120a are both necessary and sufficient to promote the appropriate localization of the receptor to lipid rafts. Deletion of the DD (CD120a.Δ321-425) prevented the receptor from being targeted to lipid rafts and resulted in a uniform plasma membrane localization. A similar loss of raft localization was also observed following pairwise deletion of the six α-helices that comprise the DD. In all situations, the loss of the ability of CD120a to become localized to lipid rafts following mutagenesis was paralleled by a failure of the receptor to initiate apoptosis. Furthermore, introduction of the lpr mutation into CD120a (CD120a.L351N) also resulted in both a loss in the ability of the receptor to signal apoptosis and to be appropriately localized to rafts. In contrast to CD120a, CD120b, which lacks a DD, is mainly expressed in the bulk plasma membrane and to a lesser extent in lipid rafts, but is absent from the Golgi complex. However, a chimeric receptor in which the DD of CD120a was fused to the cytoplasmic domain of CD120b was predominantly localized to lipid rafts. Collectively, these findings suggest that in addition to its role in CD120a signaling, an appropriately folded and functionally active DD is required for the localization of the receptor to lipid rafts.
IL-9 Inhibits Oxidative Burst and TNF-α Release in Lipopolysaccharide-Stimulated Human Monocytes Through TGF-β
Authors: Pilette Charles , Ouadrhiri Youssef , Van Snick Jacques , Renauld Jean-Christophe , Staquet Philippe , Vaerman Jean-Pierre , Sibille Yves 
Published: April 2014

AbstractIL-9 is a Th2 cytokine that exerts pleiotropic activities on T cells, B cells, mast cells, hematopoietic progenitors, and lung epithelial cells, but no effect of this cytokine has been reported so far on mononuclear phagocytes. Human blood monocytes preincubated with IL-9 for 24 h before LPS or PMA stimulation exhibited a decreased oxidative burst, even in the presence of IFN-γ. The inhibitory effect of IL-9 was specifically abolished by anti-hIL-9R mAb, and the presence of IL-9 receptors was demonstrated on human blood monocytes by FACS. IL-9 also down-regulated TNF-α and IL-10 release by LPS-stimulated monocytes. In addition, IL-9 strongly up-regulated the production of TGF-β1 by LPS-stimulated monocytes. The suppressive effect of IL-9 on the respiratory burst and TNF-α production in LPS-stimulated monocytes was significantly inhibited by anti-TGF-β1, but not by anti-IL-10Rβ mAb. Furthermore, IL-9 inhibited LPS-induced activation of extracellular signal-regulated kinase 1/2 mitogen-activated protein kinases in monocytes through a TGF-β-mediated induction of protein phosphatase activity. In contrast, IL-4, which exerts a similar inhibitory effect on the oxidative burst and TNF-α release by monocytes, acts primarily through a down-regulation of LPS receptors. Thus, IL-9 deactivates LPS-stimulated blood mononuclear phagocytes, and the mechanism of inhibition involves the potentiation of TGF-β1 production and extracellular signal-regulated kinase inhibition. These findings highlight a new target cell for IL-9 and may account for the beneficial activity of IL-9 in animal models of exaggerated inflammatory response.
IL-16 Regulation of Human Mast Cells/Basophils and Their Susceptibility to HIV-1
Authors: Qi Jian Cheng , Stevens Richard L. , Wadley Robert , Collins Andrew , Cooley Margaret , Naif Hassan M. , Nasr Najla , Cunningham Anthony , Katsoulotos Gregory , Wanigasek Yewlan , Roufogalis Basil , Krilis Steven A. 
Published: April 2014

AbstractAIDS patients often contain HIV-1-infected mast cells (MCs)/basophils in their peripheral blood, and in vivo-differentiated MCs/basophils have been isolated from the blood of asthma patients that are HIV-1 susceptible ex vivo due to their surface expression of CD4 and varied chemokine receptors. Because IL-16 is a ligand for CD4 and/or an undefined CD4-associated protein, the ability of this multifunctional cytokine to regulate the development of human MCs/basophils from nongranulated progenitors residing in cord or peripheral blood was evaluated. After 3 wk of culture in the presence of c-kit ligand, IL-16 induced the progenitors residing in the blood of normal individuals to increase their expression of chymase and tryptase about 20-fold. As assessed immunohistochemically, &gt;80% of these tryptase+ and/or chymase+ cells expressed CD4. The resulting cells responded to IL-16 in an in vitro chemotaxis assay, and this biologic response could be blocked by anti-IL-16 and anti-CD4 Abs as well as by a competitive peptide inhibitor corresponding to a sequence in the C-terminal domain of IL-16. The additional finding that IL-16 induces calcium mobilization in the HMC-1 cell line indicates that IL-16 acts directly on MCs and their committed progenitors. IL-16-treated MCs/basophils also are less susceptible to infection by an M/R5-tropic strain of HIV-1. Thus, IL-16 regulates MCs/basophils at a number of levels, including their vulnerability to retroviral infection.
Chronic Graft-Versus-Host in Ig Knockin Transgenic Mice Abrogates B Cell Tolerance in Anti-Double-Stranded DNA B Cells
Authors: Sekiguchi Debora R. , Jainandunsing Sandra M. , Fields Michele L. , Maldonado Michael A. , Madaio Michael P. , Erikson Jan , Weigert Martin , Eisenberg Robert A. 
Published: April 2014

AbstractAnti-dsDNA Abs are specific diagnostic markers of systemic lupus erythematosus, and are also implicated in kidney pathology. Anti-dsDNA B cells have been shown to be tolerized in nonautoimmune mice. The immunodysregulation that causes these cells to break tolerance is presumably part of the fundamental defects in systemic lupus erythematosus. To explore these mechanisms, we used the chronic graft-versus-host model mediated by MHC class II differences. Induction of chronic graft-vs-host in anti-DNA H chain knockin (3H9.KI) transgenic mice on a nonautoimmune background resulted in specific activation of anti-dsDNA B cells, as evidenced by high titers of soluble Ab in sera and a high frequency (70%) of anti-dsDNA B cell clones recovered as hybridomas. In addition, the λ+-anti-dsDNA B cells developed increased expression of cell surface activation markers, and concentrated in the T cell area of the follicle with an Ab-forming cell-compatible phenotype. Genetic analysis of the hybridoma clones showed strong evidence of secondary rearrangements of the L chain associated with anti-dsDNA reactivity. Thus, our study indicates that alloreactive T cell help can break tolerance in a complex manner, involving several events.
De Novo Central Nervous System Processing of Myelin Antigen Is Required for the Initiation of Experimental Autoimmune Encephalomyelitis
Authors: Tompkins Stephen Mark , Padilla Josette , Dal Canto Mauro C. , Ting Jenny P.-Y. , Van Kaer Luc , Miller Stephen D. 
Published: April 2014

AbstractWe demonstrate the absolute requirement for a functioning class II-restricted Ag processing pathway in the CNS for the initiation of experimental autoimmune encephalomyelitis (EAE). C57BL/6 (B6) mice deficient for the class II transactivator, which have defects in MHC class II, invariant chain (Ii), and H-2M (DM) expression, are resistant to initiation of myelin oligodendrocyte protein (MOG) peptide, MOG35–55-specific EAE by both priming and adoptive transfer of encephalitogenic T cells. However, class II transactivator-deficient mice can prime a suboptimal myelin-specific CD4+ Th1 response. Further, B6 mice individually deficient for Ii and DM are also resistant to initiation of both active and adoptive EAE. Although both Ii-deficient and DM-deficient APCs can present MOG peptide to CD4+ T cells, neither is capable of processing and presenting the encephalitogenic peptide of intact MOG protein. This phenotype is not Ag-specific, as DM- and Ii-deficient mice are also resistant to initiation of EAE by proteolipid protein peptide PLP178–191. Remarkably, DM-deficient mice can prime a potent peripheral Th1 response to MOG35–55, comparable to the response seen in wild-type mice, yet maintain resistance to EAE initiation. Most striking is the demonstration that T cells from MOG35–55-primed DM knockout mice can adoptively transfer EAE to wild-type, but not DM-deficient, mice. Together, these data demonstrate that the inability to process antigenic peptide from intact myelin protein results in resistance to EAE and that de novo processing and presentation of myelin Ags in the CNS is absolutely required for the initiation of autoimmune demyelinating disease.