bluuebunny/crossref_metadata_2025_split huggingface dataset:
Identification of Novel Genes Regulated by IL-12, IL-4, or TGF-β during the Early Polarization of CD4+ Lymphocytes
Authors: Lund Riikka , Aittokallio Tero , Nevalainen Olli , Lahesmaa Riitta 
Published: April 2014

AbstractTh1 and Th2 cells arise from a common precursor cell in response to triggering through the TCR and cytokine receptors for IL-12 or IL-4. This leads to activation of complex signaling pathways, which are not known in detail. Disturbances in the balance between type 1 and type 2 responses can lead to certain immune-mediated diseases. Thus, it is important to understand how Th1 and Th2 cells are generated. To clarify the mechanisms as to how IL-12 and IL-4 induce Th1 and Th2 differentiation and how TGF-β can inhibit this process, we have used oligonucleotide arrays to examine the early polarization of Th1 and Th2 cells in the presence and absence of TGF-β. In addition to genes previously implicated in the process, we have identified 20 genes with various known and unknown functions not previously associated with Th1/2 polarization. We have also further determined which genes are targets of IL-12, IL-4, and TGF-β regulation in the cells induced to polarize to Th1 and Th2 directions. Interestingly, a subset of the genes was coregulated by IL-12 or IL-4 and TGF-β. Among these genes are candidates that may modulate the balance between Th1 and Th2 responses.
Reciprocal Transfer of Class I MHC Allele Specificity between Activating Ly-49P and Ly-49W Receptors by Exchange of β4–β5 Loop Residues
Authors: Ma Brian J. , Silver Elizabeth T. , Hazes Bart , Kane Kevin P. 
Published: April 2014

AbstractReceptors of the Ly-49 multigene family regulate rodent NK cell functions. Ly-49Rs are highly polymorphic and exist in either activating or inhibitory forms. Examples of both Ly-49 receptor types have been shown to recognize class I MHC ligands. Ly-49Rs can distinguish between class I alleles, but the molecular basis of this discrimination is unknown. Two activating receptors, Ly-49P and Ly-49W, differ in class I recognition, recognizing H-2Dd, or H-2Dd and Dk, respectively. In this report, we demonstrate that specificity for H-2Dk can be transferred from Ly-49W to Ly-49P by substituting 3 aa predicted to reside in the β4–β5 loop of Ly-49W into Ly-49P. Replacement of these same residues of Ly-49W with corresponding residues in Ly-49P eliminates H-2Dk recognition while still preserving H-2Dd recognition. Further mutagenesis indicates that all 3 aa facilitate optimal class I specificity exchange. These results provide the first evidence for a specific site on Ly-49Rs, the β4–β5 loop, in determining class I MHC allele specificity.
Mast Cell Degranulation RequiresN-Ethylmaleimide-Sensitive Factor-Mediated SNARE Disassembly
Authors: Puri Niti , Kruhlak Michael J. , Whiteheart Sidney W. , Roche Paul A. 
Published: April 2014

AbstractMast cells possess specialized granules that, upon stimulation of surface FcR with IgE, fuse with the plasma membrane, thereby releasing inflammatory mediators. A family of membrane fusion proteins called SNAREs, which are present on both the granule and the plasma membrane, plays a role in the fusion of these granules with the plasma membrane of mast cells. In addition to the SNAREs themselves, it is likely that the SNARE accessory protein, N-ethylmaleimide-sensitive factor (NSF), affects the composition and structure of the SNARE complex. NSF is a cytoplasmic ATPase that disassembles the SNARE complexes. To investigate the role of NSF in mast cell degranulation, we developed an assay to measure secretion from transiently transfected RBL (rat basophilic leukemia)-2H3 mast cells (a tumor analog of mucosal mast cells). RBL-2H3 cells were cotransfected with a plasmid encoding a human growth hormone secretion reporter along with either wild-type NSF or an NSF mutant that lacks ATPase activity. Human growth hormone was targeted to and released from secretory granules in RBL-2H3 cells, and coexpression with mutant NSF dramatically inhibited regulated exocytosis from the transfected cells. Biochemical analysis of SNARE complexes in these cells revealed that overexpression of the NSF mutant decreased disassembly and resulted in an accumulation of SNARE complexes. These data reveal a role for NSF in mast cell exocytosis and highlight the importance of SNARE disassembly, or priming, in regulated exocytosis from mast cells.
Protective and Memory Immunity toHistoplasma capsulatumin the Absence of IL-10
Authors: Deepe George S. , Gibbons Reta S. 
Published: April 2014

AbstractWe determined whether the absence of IL-10 in mice influenced protective and memory immunity to Histoplasma capsulatum. IL-10−/− mice cleared primary and secondary infection more rapidly than wild-type controls. Administration of mAb to TNF-α or IFN-γ, but not GM-CSF, abrogated protection in naive IL-10−/− mice; mAb toTNF-α, but not IFN-γ or GM-CSF, subverted protective immunity in secondary histoplasmosis. The inflammatory cell composition in IL-10−/− mice was altered in those given mAb to IFN-γ or TNF-α. More Gr-1+ and Mac-3+ cells were present in lungs of IL-10−/− mice given mAb to IFN-γ, and treatment with mAb to TNF-α sharply reduced the number of CD8+ cells in lungs of IL-10−/− mice. We ascertained whether the lack of IL-10 modulated memory T cell generation or the protective function of cells. The percentage of CD3+, CD44high, CD62low, and IFN-γ+ cells in IL-10−/− mice was higher than that of wild-type at day 7 but not day 21 or 49 after immunization. Fewer splenocytes from immunized IL-10−/− mice were required to mediate protection upon adoptive transfer into infected TCR αβ−/− mice. Hence, deficiency of IL-10 confers a salutary effect on the course of histoplasmosis, and the beneficial effects of IL-10 deficiency require endogenous TNF-α and/or IFN-γ. Memory cell generation was transiently increased in IL-10−/− mice, but the protective function conferred by cells from these mice following immunization is strikingly more vigorous than that of wild-type.
Myeloid C3 Determines Induction of Humoral Responses to Peripheral Herpes Simplex Virus Infection
Authors: Verschoor Admar , Brockman Mark A. , Gadjeva Mihaela , Knipe David M. , Carroll Michael C. 
Published: April 2014

AbstractThe complement system, in addition to its role in innate immunity, is an important regulator of the B cell response. Complement exists predominantly in the circulation and although the primary source is hepatic, multiple additional cellular sources have been described that can contribute substantially to the complement pool. To date, however, complement produced by these secondary sources has been deemed redundant to that secreted by the liver. In contrast, using a bone marrow chimeric model, we observed that C3 synthesis by myeloid cells, a relatively minor source of complement, provided a critical function during the induction of humoral responses to peripheral HSV infection. Anti-viral Ab, as generated in an efficient humoral response, has been associated with protection from severe consequences of HSV dissemination. This report offers insight into the generation of the adaptive immune response in the periphery and describes a unique role for a nonhepatic complement source.
Epitope Escape Mutation and Decay of Human Immunodeficiency Virus Type 1-Specific CTL Responses
Authors: Jamieson Beth D. , Yang Otto O. , Hultin Lance , Hausner Mary Ann , Hultin Patricia , Matud Jose , Kunstman Kevin , Killian Scott , Altman John , Kommander Kristina , Korber Bette , Giorgi Janis , Wolinsky Steven 
Published: April 2014

AbstractTo investigate possible mechanisms behind HIV-1 escape from CTL, we performed detailed longitudinal analysis of Gag (SLYNTVATL)- and RT (ILKEPVHGV)-specific CTL responses and plasma epitope sequences in five individuals. Among those with CTL against consensus epitope sequences, epitope mutations developed over several years, invariably followed by decay of the CTL targeting the consensus epitopes. The maturation state of the CTL varied among individuals and appeared to affect the rate of epitope mutation and CTL decay, despite similar IFN-γ production. Escape mutations were oligoclonal, suggesting fitness constraints. The timing of escape indicated that the net selective advantage of escape mutants was slight, further underscoring the importance of understanding factors determining selective pressure and viral fitness in vivo. Our data show surprisingly consistent decay of CTL responses after epitope escape mutation and provide insight into potential mechanisms for both immune failure and shifting CTL specificities.
Alveolar Macrophage Apoptosis Contributes to Pneumococcal Clearance in a Resolving Model of Pulmonary Infection
Authors: Dockrell David H. , Marriott Helen M. , Prince Lynne R. , Ridger Victoria C. , Ince Paul G. , Hellewell Paul G. , Whyte Moira K. B. 
Published: April 2014

AbstractThe role of alveolar macrophages (AM) in host defense against pulmonary infection has been difficult to establish using in vivo models. This may reflect a reliance on models of fulminant infection. To establish a unique model of resolving infection, with which to address the function of AM, C57BL/6 mice received low-dose intratracheal administration of pneumococci. Administration of low doses of pneumococci produced a resolving model of pulmonary infection characterized by clearance of bacteria without features of pneumonia. AM depletion in this model significantly increased bacterial outgrowth in the lung. Interestingly, a significant increase in the number of apoptotic AM was noted with the low-dose infection as compared with mock infection. Caspase inhibition in this model decreased AM apoptosis and increased the number of bacteremic mice, indicating a novel role for caspase activation in pulmonary innate defense against pneumococci. These results suggest that AM play a key role in clearance of bacteria from the lung during subclinical infection and that induction of AM apoptosis contributes to the microbiologic host defense against pneumococci.
Fibrinogen Depletion Attenuates Staphyloccocus aureus Infection by Preventing Density-Dependent Virulence Gene Up-Regulation
Authors: Rothfork Jacob M. , Dessus-Babus Sophie , Van Wamel Willem J. B. , Cheung Ambrose L. , Gresham Hattie D. 
Published: April 2014

Abstract
Staphylococcus aureus undergoes a density-dependent conversion in phenotype from tissue-adhering to tissue-damaging and phagocyte-evading that is mediated in part by the quorum-sensing operon, agr, and its effector, RNAIII. Contributions of host factors to this mechanism for regulating virulence have not been studied. We hypothesized that fibrinogen, as a component of the inflammatory response, could create spatially constrained microenvironments around bacteria that increase density independently of bacterial numbers and thus potentiate quorum-sensing-dependent virulence gene expression. Here we show that transient fibrinogen depletion significantly reduces the bacterial burden and the consequential morbidity and mortality during experimental infection with wild-type S. aureus, but not with bacteria that lack expression of the quorum-sensing operon, agr. In addition, it inhibits in vivo activation of the promoter for the agr effector, RNAIII, and downstream targets of RNAIII, including α hemolysin and capsule production. Moreover, both in vitro and in vivo, the mechanism for promoting this phenotypic switch in virulence involves clumping of the bacteria, demonstrating that S. aureus responds to fibrinogen-mediated bacterial clumping by enhancing density-dependent virulence gene expression. These data demonstrate that down-modulation of specific inflammatory components of the host that augment bacterial quorum sensing can be a strategy for enhancing host defense against infection.
Activation of a Subset of Human NK Cells upon Contact with Plasmodium falciparum-Infected Erythrocytes
Authors: Artavanis-Tsakonas Katerina , Eleme Konstantina , McQueen Karina L. , Cheng Nathalie W. , Parham Peter , Davis Daniel M. , Riley Eleanor M. 
Published: April 2014

Abstract
Human NK cells are the earliest source of the protective cytokine IFN-γ when PBMC from nonimmune donors are exposed to Plasmodium falciparum-infected RBC (iRBC) in vitro. In this study, we show that human NK cells form stable conjugates with iRBC but not with uninfected RBC and that induction of IFN-γ synthesis is dependent on direct contact between the NK cell and the iRBC. NK cells respond to iRBC only in the presence of a source of IL-12/IL-18 and the subset of NK cells that preferentially respond to iRBC express high levels of the lectin-like receptor CD94/NKG2A. There is heterogeneity between donors in their ability to respond to iRBC. DNA analysis has revealed considerable heterogeneity of killer Ig-like receptor (KIR) genotype among the donor population and has identified 21 new KIR allelic variants in the donors of African and Asian descent. Importantly, we find evidence for significant associations between KIR genotype and NK responsiveness to iRBC. This emphasizes the need for large-scale population-based studies to address associations between KIR genotype and susceptibility to malaria.
Peritoneal Cavity B Cells Are Precursors of Splenic IgM Natural Antibody-Producing Cells
Authors: Kawahara Toshiyasu , Ohdan Hideki , Zhao Guiling , Yang Yong-Guang , Sykes Megan 
Published: April 2014

AbstractPeritoneal cavity B-1 cells are believed to produce IgM natural Abs. We have used α1,3-galactosyltransferase-deficient (GalT−/−) mice, which, like humans, produce IgM natural Abs against the carbohydrate epitope Galα1,3Gal (Gal), to demonstrate that peritoneal cavity B-1b cells with anti-Gal receptors produce anti-Gal IgM Abs only after LPS stimulation. Likewise, peritoneal cavity cells of GalT−/− and wild-type mice do not produce IgM Abs of other specificities without LPS stimulation. Development of Ab-secreting capacity is associated with loss of CD11b/CD18 (Mac-1) expression. In contrast, there are large numbers of cells producing anti-Gal and other IgM Abs in fresh splenocyte preparations from GalT−/− and (for non-Gal specificities) wild-type mice. These cells are Mac-1− but otherwise B-1b-like in their phenotype. We therefore hypothesized a pathway wherein peritoneal cavity B cells migrate into the spleen after activation in vivo and lose Mac-1 expression to become IgM Ab-producing cells. Consistent with this possibility, splenectomy reduced anti-Gal Ab production after immunization of GalT−/− mice with Gal-positive rabbit RBC. Furthermore, splenectomized B6 GalT−/−, Ig μ-chain mutant (μ−/−) (both Gal- and B cell-deficient) mice produced less anti-Gal IgM than nonsplenectomized controls after adoptive transfer of peritoneal cavity cells from B6 GalT−/− mice. When sorted GalT−/− Mac-1+ peritoneal cavity B cells were adoptively transferred to B6 GalT−/−, μ−/− mice, IgM Abs including anti-Gal appeared, and IgM-producing and Mac1− B cells were present in the spleen 5 wk after transfer. These findings demonstrate that peritoneal cavity Mac-1+ B-1 cells are precursors of Mac-1− splenic IgM Ab-secreting cells.
Immunodominance of an Antiviral Cytotoxic T Cell Response Is Shaped by the Kinetics of Viral Protein Expression
Authors: Probst Hans Christian , Tschannen Kathrin , Gallimore Awen , Martinic Marianne , Basler Michael , Dumrese Tilman , Jones Emma , van den Broek Maries F. 
Published: April 2014

AbstractLymphocytic choriomeningitis virus (LCMV) infection induces a protective CTL response consisting of gp- and nucleoprotein (NP)-specific CTL. We find that a small load of LCMV led to immunodominance of NP-CTL, whereas a large viral load resulted in dominance of gp-CTL. This is the first study describing that immunodominance is not fixed after infection with a given pathogen, but varies with the viral load instead. We assumed higher Ag sensitivity for NP-CTL, which would explain their preferential priming at low viral load, as well as their overstimulation resulting in selective exhaustion at high viral load. The higher Ag sensitivity of NP-CTL was due to faster kinetics of NP-epitope presentation. Thus, we uncover a novel factor that impinges upon immunodominance and is related to the kinetics of virus protein expression. We propose that CTL against early viral proteins swiftly interfere with virus replication, resulting in efficient protection. If these “early” CTL fail in immediate virus control, they are activated in the face of higher viral load compared with “late” CTL and are therefore prone to be exhausted. Thus, the observed absence of early CTL in persistent infections might not be the cause, but rather the consequence of viral persistence.
Autocrine/Paracrine IL-15 That Is Required for Type I IFN-Mediated Dendritic Cell Expression of MHC Class I-Related Chain A and B Is Impaired in Hepatitis C Virus Infection
Authors: Jinushi Masahisa , Takehara Tetsuo , Tatsumi Tomohide , Kanto Tatsuya , Groh Veronika , Spies Thomas , Suzuki Takahiro , Miyagi Takuya , Hayashi Norio 
Published: April 2014

Abstract
We previously reported that monocyte-derived dendritic cells activate resting NK cells by expressing MHC class I-related chain A and B (MICA/B), ligands for NKG2D, in response to IFN-α, but the MICA/B expression was severely impaired in patients with chronic hepatitis C virus (HCV) infection. In the present study, we examined induction of MICA/B on DCs by various innate cytokines and found that DCs from either healthy donors or HCV-infected individuals, upon IL-15 stimulation, express MICA/B and can activate NK cells, which is solely dependent on MICA/B-NKG2D interaction. Of interest is the finding that IL-15- and type I IFN-mediated induction of MICA/B in healthy donors is completely inhibited when DCs are incubated in the presence of anti-IFN-α/βR or anti-IL-15Rα, respectively, suggesting interdependent roles of these cytokines in MICA/B expression. Indeed, DCs produced IL-15 in response to type I IFN, whereas they directly produced IFN-β, in response to IL-15, which was followed by the production of IFN-α. In HCV-infected individuals, type I IFN-mediated production of IL-15 was virtually absent, but IL-15-mediated production of type I IFN was not compromised, which is consistent with the distinct ability of these cytokines to induce MICA/B in these patients. The present study demonstrates that IL-15 and type I IFN lead to DC expression of MICA/B and subsequent DC activation of NK cells, which is critically dependent on each other’s autocrine/paracrine effect, and suggests that impaired IL-15 production is one of the mechanisms of the aberrant response of DC to type I IFN in HCV-infected patients.
Differential Induction of TGF-β Regulates Proinflammatory Cytokine Production and Determines the Outcome of Lethal and NonlethalPlasmodium yoeliiInfections
Authors: Omer Fakhreldin M. , de Souza J. Brian , Riley Eleanor M. 
Published: April 2014

AbstractTransforming growth factor-β is an essential moderator of malaria-induced inflammation in mice. In this study, we show that the virulence of malaria infections is dependent upon the cellular source of TGF-β and the timing of its production. C57BL/6 mice infected with a nonlethal (Py17X) strain of Plasmodium yoelii produce TGF-β from 5 days postinfection; this correlates with resolution of parasitemia, down-regulation of TNF-α, and full recovery. In contrast, infection with the lethal strain Py17XL induces high levels of circulating TGF-β within 24 h; this is associated with delayed and blunted IFN-γ and TNF-α responses, failure to clear parasites, and 100% mortality. Neutralization of early TGF-β in Py17XL infection leads to a compensatory increase in IL-10 production, while simultaneous neutralization of TGF-β and IL-10R signaling leads to up-regulation of TNF-α and IFN-γ, prolonged survival in all, and ultimate resolution of infection in 40% of Py17XL-infected animals. TGF-β production can be induced in an Ag-specific manner from splenocytes of infected mice, and by cross-linking surface CTLA-4. CD25+ and CD8+ cells are the primary source of TGF-β following Py17X stimulation of splenocytes, whereas Py17XL induces significant production of TGF-β from adherent cells. In mice immunized against Py17XL, the early TGF-β response is inhibited and is accompanied by significant up-regulation of IFN-γ and TNF-α and rapid resolution of challenge infections.
TRANCE-RANK Costimulation is Required for IL-12 Production and the Initiation of a Th1-Type Response toLeishmania majorInfection in CD40L-Deficient Mice
Authors: Padigel Udaikumar M. , Kim Nacksung , Choi Yongwon , Farrell Jay P. 
Published: April 2014

AbstractBlockade of TNF-related activation-induced cytokine (TRANCE)-receptor activator of NF-κB (RANK) interaction reverses healing in CD40L−/− mice infected with Leishmania major. Although previous studies demonstrated a requirement for CD40-CD40L interaction in production of IL-12 and the development of resistance to Leishmania infection, we recently showed that CD40L−/− mice control infection when inoculated with low numbers of parasites and that cells from these mice produce IL-12. Here, we show that in vivo treatment with a TRANCE receptor fusion protein results in a decrease in numbers of IL-12 producing cells as well as a shift from a dominant Th1 to Th2 type response in infected mice. These results demonstrate that CD40L−/− mice use the TRANCE-RANK costimulatory pathway to promote IL-12 production and the activation of a protective Th1 type response.
A Loss-of-Function Polymorphism in the Human P2X7 Receptor Abolishes ATP-Mediated Killing of Mycobacteria
Authors: Saunders Bernadette M. , Fernando Suran L. , Sluyter Ronald , Britton Warwick J. , Wiley James S. 
Published: April 2014

Abstract
Protective immunity to mycobacterial infections requires activation of the antibacterial mechanisms of infected macrophages. It has previously been reported that ATP treatment of mycobacteria-infected macrophages induces apoptosis mediated via the P2X7 pathway and that this leads to the death of both the host cell and the internalized bacilli. We have recently identified a single nucleotide polymorphism in the P2X7 gene (1513A→C), with 1–2% prevalence in the homozygous state, which codes for a nonfunctional receptor. IFN-γ-primed, mycobacteria-infected macrophages from wild-type individuals were incubated with ATP and this induced apoptosis and reduced mycobacterial viability by 90%. Similar treatment of macrophages from individuals homozygous for the 1513C polymorphism failed to induce apoptosis and did not lead to mycobacterial killing via the P2X7-mediated pathway. These data demonstrate that a single nucleotide polymorphism in the P2X7 gene can allow survival of mycobacteria within infected host cells.