bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modulation of Human T Cell Responses and Macrophage Functions by Onchocystatin, a Secreted Protein of the Filarial NematodeOnchocerca volvulus
Authors: Schönemeyer Annett , Lucius Richard , Sonnenburg Bettina , Brattig Norbert , Sabat Robert , Schilling Klaus , Bradley Janette , Hartmann Susanne 
Published: April 2014

AbstractImmune responses of individuals infected with filarial nematodes are characterized by a marked cellular hyporesponsiveness and a shift of the cytokine balance toward a Th2/Th3 response. This modulation of cellular immune responses is considered as an important mechanism to avoid inflammatory immune responses that could eliminate the parasites. We investigated the immunomodulatory potential of a secreted cysteine protease inhibitor (onchocystatin) of the human pathogenic filaria Onchocerca volvulus. Recombinant onchocystatin (rOv17), a biologically active cysteine protease inhibitor that inhibited among others the human cysteine proteases cathepsins L and S, suppressed the polyclonally stimulated and the Ag-driven proliferation of human PBMC. Stimulated as well as unstimulated PBMC in the presence of rOv17 produced significantly more IL-10, which was paralleled in some situations by a decrease of IL-12p40 and preceded by an increase of TNF-α. At the same time, rOv17 reduced the expression of HLA-DR proteins and of the costimulatory molecule CD86 on human monocytes. Neutralization of IL-10 by specific Abs restored the expression of HLA-DR and CD86, whereas the proliferative block remained unaffected. Depletion of monocytes from the PBMC reversed the rOv17-induced cellular hyporeactivity, indicating monocytes to be the target cells of immunomodulation. Therefore, onchocystatin has the potential to contribute to a state of cellular hyporesponsiveness and is a possible pathogenicity factor essential for the persistence of O. volvulus within its human host.
Activation of Eotaxin-3/CCL26 Gene Expression in Human Dermal Fibroblasts Is Mediated by STAT6
Authors: Hoeck Jutta , Woisetschläger Maximilian 
Published: April 2014

AbstractAllergic inflammatory conditions such as asthma are characterized by an accumulation of eosinophils at sites of inflammation. Eotaxin-3/CCL26 is a member of the family of CC chemokines, which are known to be potent chemoattractants for eosinophils. This chemokine was shown to be up-regulated by IL-4 and IL-13 in endothelial cells. This study demonstrates that eotaxin-3 transcription and eotaxin-3 protein expression are stimulated by IL-4 and IL-13 in a time- and dose-dependent fashion in human dermal fibroblasts. In contrast to eotaxin-1/CCL11, TNF-α could not act as inducer on its own nor did it synergize with IL-4. The activities of eotaxin-3 promoter luciferase constructs were significantly increased by IL-4 and IL-13 in human dermal fibroblasts. This effect was mediated by a binding site for the transcription factor STAT6 in the eotaxin-3 promoter sequence. Mutations in the STAT6 binding site abrogated up-regulation of eotaxin-3 promoter activity. In STAT6-defective human embryonic kidney 293 cells, the wild-type luciferase construct, but not the STAT6 binding mutant, was inducible by IL-4 only upon cotransfection of STAT6 expression vector. In addition, eotaxin-3 protein was detectable in the supernatants of STAT6-transfected human embryonic kidney 293 cells upon IL-4 or IL-13 stimulation. In the same experiments, TNF-α induced activation of the monocyte chemoattractant protein-1/CCL2 gene was independent of STAT6 transfection. These results indicate that IL-4 and IL-13 activate eotaxin-3 gene expression in a STAT6-dependent fashion. Although both eotaxin-1 and -3 are regulated by this transcription factor, the response of the eotaxin-3 gene to TNF-α stimulation appears to be different.
The HA-2 Minor Histocompatibility Antigen Is Derived from a Diallelic Gene Encoding a Novel Human Class I Myosin Protein
Authors: Pierce Richard A. , Field Erin D. , Mutis Tuna , Golovina Tatiana N. , Kap-Herr Chris Von , Wilke. Martina , Pool Jos , Shabanowitz Jeffrey , Pettenati Mark J. , Eisenlohr Laurence C. , Hunt Donald F. , Goulmy Els , Engelhard Victor H. 
Published: April 2014

Abstract
Human minor histocompatibility Ags (mHag) present significant barriers to successful bone marrow transplantation. However, the structure of human mHag and the basis for antigenic disparities are still largely unknown. Here we report the identification of the gene encoding the human mHag HA-2 as a previously unknown member of the class I myosin family, which we have designated MYO1G. The gene is located on the short arm of chromosome 7. Expression of this gene is limited to cells of hemopoietic origin, in keeping with the previously defined tissue expression of the HA-2 Ag. RT-PCR amplification of MYO1G from different individuals led to the identification of two genetic variants, designated MYO1GV and MYO1GM. The former encodes the peptide sequence previously shown to be the HA-2 epitope (YIGEVLVSV), whereas the latter shows a single amino acid change in this peptide (YIGEVLVSM). This change has only a modest effect on peptide binding to the class I MHC-restricted element HLA-A*0201, and a minimal impact on recognition by T cells when added exogenously to target cells. Nonetheless, as detected using either T cells or mass spectrometry, this amino acid change results in a failure of the latter peptide to be presented at the surface of cells that express MYO1GM endogenously. These studies have thus identified a new mHag-encoding gene, and thereby provide additional information about both the genetic origins of human mHag as well as the underlying basis of an Ag-positive vs Ag-negative state.
Down-Regulation of CD28 Expression by TNF-α
Authors: Bryl Ewa , Vallejo Abbe N. , Weyand Cornelia M. , Goronzy Jörg J. 
Published: April 2014

AbstractAging and chronic inflammatory syndromes, such as rheumatoid arthritis, are associated with high frequencies of CD4+CD28null T cells, which are rarely seen in healthy individuals younger than 40 years. Inasmuch as rheumatoid arthritis and aging are also associated with elevated levels of TNF-α, we examined whether this proinflammatory cytokine influences CD28 expression. Incubation of T cell lines and clones as well as Jurkat cells with TNF-α induced a reduction in the levels of cell surface expression of CD28. This effect of TNF-α was reversible; however, continuous culture of CD4+CD28+ T cell clones in TNF-α resulted in the appearance of a CD28null subset. In reporter gene bioassays, TNF-α was found to inhibit the activity of the CD28 minimal promoter. Inactivation of the promoter was accompanied by a marked reduction in DNA-protein complex formation by two DNA sequence motifs corresponding to the transcriptional initiator of the CD28 gene. Indeed, in vitro transcription assays showed that nuclear extracts from TNF-α-treated cells failed to activate transcription of DNA templates under the control of a consensus TATA box and the CD28 initiator sequences. In contrast, similar extracts from unstimulated T cells supported transcription. These results demonstrate that TNF-α directly influences CD28 gene transcription. We propose that the emergence of CD4+CD28null T cells in vivo is facilitated by increased production of TNF-α.
Antibody Repertoire Development in Fetal And Neonatal Piglets. IV. Switch Recombination, Primarily in Fetal Thymus, Occurs Independent of Environmental Antigen and Is Only Weakly Associated with Repertoire Diversification
Authors: Butler John E. , Sun Jishan , Weber Patrick , Ford Steven P. , Rehakova Zuzana , Sinkora Jiri , Lager Kelly 
Published: April 2014

AbstractThe epitheliochorial placenta of swine is considered a barrier to Ag and selective transport of IgG, so this species should be an excellent model with which to determine whether switch recombination is Ag dependent. Analysis of Ig levels and Ig isotype profiles in &gt;150 normal and virus-infected fetuses from 38–110 days of gestation (DG) suggested that IgG, IgA, and IgM were most likely the result of de novo fetal synthesis. Although transcripts for IgM could be recovered at DG 50 (114 DG is full gestation) in all major fetal lymphoid tissues, those for IgG and IgA first became prominent at 60 DG in thymus, and transcription and spontaneous secretion became especially pronounced in this organ in older fetuses. Data on transcription, secretion, and serum isotype profiles suggest that although all fetal IgA and IgM may result from de novo synthesis, some IgG may result from low-level selective transport. The complementarity-determining region 3 spectratypes of thymic IgA and IgG transcripts at 70 and 90 days, respectively, were as polyclonal as that of IgM, indicating a broad repertoire of switched B cells although the VDJs transcribed with these switched isotypes in normal fetuses were not diversified in comparison to those from animals exposed to environmental Ags such as age-matched, virus-infected fetuses, colonized isolator piglets, and conventional adults. However, VDJs expressed with switched isotypes were more diversified than those expressed with IgM. Thus, switch recombination in fetal life does not appear to be driven by environmental Ag and is only weakly coupled to VDJ diversification. These findings, and the fact that the oligoclonal IgA and IgM repertoires in a noninductive site of the mucosal immune system (parotid gland) become polyclonal in piglets reared germfree, suggest that initial expansion of the switched cells in the B cell compartment of fetal and neonatal piglets is not driven by environmental Ag.
T Cell Selection and Differential Activation on Structurally Related HLA-DR4 Ligands
Authors: Gebe John A. , Novak Erik J. , Kwok William W. , Farr Andy G. , Nepom Gerald T. , Buckner Jane H. 
Published: April 2014

AbstractPlasticity of TCR interactions during CD4+ T cell activation by an MHC-peptide complex accommodates variation in the peptide or MHC contact sites in which recognition of an altered ligand by the T cell can modify the T cell response. To explore the contribution of this form of TCR cross-recognition in the context of T cell selection on disease-associated HLA molecules, we have analyzed the relationship between TCR recognition of the DRB1*0401- and DRB1*0404-encoded HLA class II molecules associated with rheumatoid arthritis. Thymic reaggregation cultures demonstrated that CD4+ T cells selected on either DRB1*0401 or DRB1*0404 could be subsequently activated by the other MHC molecule. Using HLA tetramer technology we identify hemagglutinin residue 307–319-specific T cells restricted by DRB1*0401, but activated by hemagglutinin residues 307–319, in the context of DRB1*0404. One such clone exhibits an altered cytokine profile upon activation with the alternative MHC ligand. This altered phenotype persists when both class II molecules are present. These findings directly demonstrate that T cells selected on an MHC class II molecule carry the potential for activation on altered self ligands when encountering Ags presented on a related class II molecule. In individuals heterozygous for these alleles the possibility of TCR cross-recognition could lead to an aberrant immune response.
HS1,2 Enhancer Regulation of Germline ε and γ2b Promoters in Murine B Lymphocytes: Evidence for Specific Promoter-Enhancer Interactions
Authors: Laurencikiene Jurga , Deveikaite Vilma , Severinson Eva 
Published: April 2014

AbstractDuring an immune response, activated B cells develop into high rate Ig-secreting plasma cells. They also switch from production of IgM to IgG, IgA, or IgE. This process requires a DNA recombination event, which is regulated at the transcriptional level by the production of isotype-specific, sterile germline (GL) transcripts. Induction of these transcripts is controlled by GL promoters and, possibly, by IgH 3′ enhancers. We investigated the interaction of the GL ε and γ2b promoters with the HS1,2 enhancer using transiently transfected mouse primary B cells and cell lines. The constructs used for the transfections contained a GL promoter upstream and HS1,2 downstream of a luciferase reporter gene. Both GL ε and γ2b promoters synergized strongly with the HS1,2 enhancer in activated primary B cells, a mature B cell line, and a plasma cell line. We show that the major activity of HS1,2 in activated primary B cells occurs within a 310-bp fragment that includes NF-κB, OCT, and NF of activated B cells (Ets/AP-1) sites. By mutating the consensus sequences for various transcription factors, we have determined which sites in HS1,2 are important for synergy with the GL ε and γ2b promoters. Our findings indicate that different sites in HS1,2 might selectively interact with the GL ε and γ2b promoters. We also provide evidence that B cell-specific activator protein is not an absolute suppressor of HS1,2 activity.
Humanization and Epitope Mapping of Neutralizing Anti-Human Fas Ligand Monoclonal Antibodies: Structural Insights into Fas/Fas Ligand Interaction
Authors: Nisihara Tsukasa , Ushio Yoshitaka , Higuchi Hirohumi , Kayagaki Nobuhiko , Yamaguchi Noriko , Soejima Kenji , Matsuo Seishi , Maeda Hiroaki , Eda Yasuyuki , Okumura Ko , Yagita Hideo 
Published: April 2014

Abstract
Fas ligand (L)/CD95L, a proapoptotic member of the TNF family, is a potential target for clinical intervention in various diseases. In the present study, we generated a humanized anti-human FasL mAb and characterized the epitopes of neutralizing mAbs by extensive alanine-scanning mutagenesis of human FasL. The predicted molecular model of FasL trimer revealed that the mAbs recognize largely overlapped conformational epitopes that are composed of two clusters, one around the outer tip-forming D-E loop and another near the top of FasL. Both of these sites on FasL are critically involved in the direct interaction with the corresponding receptor, Fas. These results suggest that the mAbs efficiently neutralize FasL cytotoxicity by masking both of these FasL/Fas contact sites.
Crystal Structures of Two Closely Related but Antigenically Distinct HLA-A2/Melanocyte-Melanoma Tumor-Antigen Peptide Complexes
Authors: Sliz Piotr , Michielin Olivier , Cerottini Jean-Charles , Luescher Immanuel , Romero Pedro , Karplus Martin , Wiley Don C. 
Published: April 2014

Abstract
We have determined high-resolution crystal structures of the complexes of HLA-A2 molecules with two modified immunodominant peptides from the melanoma tumor-associated protein Melan-A/Melanoma Ag recognized by T cells-1. The two peptides, a decamer and nonamer with overlapping sequences (ELAGIGILTV and ALGIGILTV), are modified in the second residue to increase their affinity for HLA-A2. The modified decamer is more immunogenic than the natural peptide and a candidate for peptide-based melanoma immunotherapy. The crystal structures at 1.8 and 2.15 Å resolution define the differences in binding modes of the modified peptides, including different clusters of water molecules that appear to stabilize the peptide-HLA interaction. The structures suggest both how the wild-type peptides would bind and how three categories of cytotoxic T lymphocytes with differing fine specificity might recognize the two peptides.
An Important Role of CDK Inhibitor p18INK4c in Modulating Antigen Receptor-Mediated T Cell Proliferation
Authors: Kovalev Grigoriy I. , Franklin David S. , Coffield V. McNeil , Xiong Yue , Su Lishan 
Published: April 2014

Abstract
The inhibitors of cyclin-dependent kinase (CDK) 4 (INK4) bind CDK4/6 to prevent their association with D-cyclins and G1 cell cycle initiation and progression. We report here that among the seven CDK inhibitors, p18INK4c played an important role in modulating TCR-mediated T cell proliferation. Loss of p18INK4c in T cells led to hyperproliferation in response to CD3 stimulation. p18INK4c-null mice developed lymphoproliferative disorder and T cell lymphomas. Expression of IL-2, IL-2R-α, and the major G1 cell cycle regulatory proteins was not altered in p18-null T cells. Both FK506 and rapamycin efficiently inhibited proliferation of p18-null T cells. In activated T cells, p18INK4c remained constant, and preferentially associated with and inhibited CDK6 but not CDK4. We propose that p18INK4c sets an inhibitory threshold in T cells and one function of CD28 costimulation is to counteract the p18INK4c inhibitory activity on CDK6-cyclin D complexes. The p18INK4c protein may provide a novel target to modulate T cell immunity.
Antigen-Specific CD8+ T Cells Persist in the Upper Respiratory Tract Following Influenza Virus Infection
Authors: Wiley James A. , Hogan Robert J. , Woodland David L. , Harmsen Allen G. 
Published: April 2014

Abstract
Because little is known about lymphocyte responses in the nasal mucosa, lymphocyte accumulation in the nasal mucosa, nasal-associated lymphoid tissue (NALT), and cervical lymph nodes (CLN) were determined after primary and heterosubtypic intranasal influenza challenge of mice. T cell accumulation peaked in the nasal mucosa on day 7, but peaked slightly earlier in the CLN (day 5) and later (day 10) in the NALT. Tetrameric staining of nasal mucosal cells revealed a peak accumulation of CD8 T cells specific for either the H-2Db influenza nucleoprotein epitope 366–374 (DbNP366) or the H-2Db polymerase 2 protein epitope 224–233 (DbPA224) at 7 days. By day 13, DbPA224-specific CD8 T cells were undetectable in the mucosa, whereas DbNP366-specific CD8 T cells persisted for at least 35 days in the mucosa and spleen. After heterosubtypic virus challenge, the accumulation of CD8 T cells in the nasal mucosa was quicker, more intense, and predominantly DbNP366 specific relative to the primary inoculation. The kinetics and specificity of the CD8 T cell response were similar to those in the CLN, but the responses in the NALT and spleen were again slower and more protracted. These results indicate that similar to what was reported in the lung, DbNP366-specific CD8 T cells persist in the nasal mucosa after primary influenza infection and predominate in an intensified nasal mucosal response to heterosubtypic challenge. In addition, differences in the kinetics of the CD8 T cell responses in the CLN, NALT, and spleen suggest different roles of these lymphoid tissues in the mucosal response.
ATP-Mediated Killing of Intracellular Mycobacteria by Macrophages Is a P2X7-Dependent Process Inducing Bacterial Death by Phagosome-Lysosome Fusion
Authors: Fairbairn Ian P. , Stober Carmel B. , Kumararatne Dinakantha S. , Lammas David A. 
Published: April 2014

AbstractMycobacterium tuberculosis survives within host macrophages by actively inhibiting phagosome fusion with lysosomes. Treatment of infected macrophages with ATP induces both cell apoptosis and rapid killing of intracellular mycobacteria. The following studies were undertaken to characterize the effector pathway(s) involved. Macrophages were obtained from p47phox and inducible NO synthase gene-disrupted mice (which are unable to produce reactive oxygen and nitrogen radicals, respectively) and P2X7 gene-disrupted mice. RAW murine macrophages transfected with either the natural resistance-associated macrophage protein gene 1 (Nramp1)-resistant or Nramp1-susceptible gene were also used. The cells were infected with bacille Calmette-Guérin (BCG), and intracellular mycobacterial trafficking was analyzed using confocal and electron microscopy. P2X7 receptor activation was essential for effective ATP-induced mycobacterial killing, as its bactericidal activity was radically diminished in P2X7−/− macrophages. ATP-mediated killing of BCG within p47phox−/−, inducible NO synthase−/−, and Nramps cells was unaffected, demonstrating that none of these mechanisms have a role in the ATP/P2X7 effector pathway. Following ATP stimulation, BCG-containing phagosomes rapidly coalesce and fuse with lysosomes. Blocking of macrophage phospholipase D activity with butan-1-ol blocked BCG killing, but not macrophage death. ATP stimulates phagosome-lysosome fusion with concomitant mycobacterial death via P2X7 receptor activation. Macrophage death and mycobacterial killing induced by the ATP/P2X7 signaling pathway can be uncoupled, and diverge proximal to phospholipase D activation.
ATP Stimulates Human Macrophages to Kill Intracellular Virulent Mycobacterium tuberculosis Via Calcium-Dependent Phagosome-Lysosome Fusion
Authors: Kusner David J. , Barton James A. 
Published: April 2014

Abstract
Advances in therapy for tuberculosis will require greater understanding of the molecular mechanisms of pathogenesis and the human immune response in this disease. Exposure of Mycobacterium tuberculosis-infected human macrophages to extracellular ATP (ATPe) results in bacterial killing, but the molecular mechanisms remain incompletely characterized. In this study, we demonstrate that ATPe-induced bactericidal activity toward virulent M. tuberculosis requires an increase in cytosolic Ca2+ in infected macrophages. Based on our previous work with primary infection of human macrophages, we hypothesized that the Ca2+ dependence of ATP-induced killing of intracellular M. tuberculosis was linked to promotion of phagosome-lysosome fusion. Using confocal laser-scanning microscopy, we demonstrate that ATPe induces fusion of the M. tuberculosis-containing phagosome with lysosomes, defined by accumulation of three lysosomal proteins and an acidophilic dye. Stimulation of phagosome-lysosome fusion by ATPe exhibited distinct requirements for both Ca2+ and phospholipase D and was highly correlated with killing of intracellular bacilli. Thus, key signal transduction pathways are conserved between two distinct models of human macrophage antituberculous activity: primary infection of naive macrophages and physiologic stimulation of macrophages stably infected with M. tuberculosis.
Predominant Role of Toll-Like Receptor 2 Versus 4 in Chlamydia pneumoniae-Induced Activation of Dendritic Cells
Authors: Prebeck Sigrid , Kirschning Carsten , Dürr Susanne , da Costa Clarissa , Donath Bernadette , Brand Korbinian , Redecke Vanessa , Wagner Hermann , Miethke Thomas 
Published: April 2014

Abstract
Chlamydia pneumoniae is an obligate intracellular human pathogen causing diseases such as pneumonia, bronchitis, and pharyngitis. Because of its intracellular replication, cell-mediated immune responses are needed to mediate successful defenses of the host. Because dendritic cells play a central role in linking innate immunity and Ag-specific cell-mediated immune responses we asked whether dendritic cells are activated upon contact with C. pneumoniae and whether known Toll like receptors (TLR) are involved in this process. Here we show that C. pneumoniae was taken up by bone marrow-derived murine dendritic cells. Ingested C. pneumoniae appeared to be unable to develop mature inclusion inside dendritic cells. Furthermore, upon contact with C. pneumoniae dendritic cells were potently stimulated because NF-κB was activated and translocated to the nucleus, cytokines like IL-12p40 and TNF-α were secreted, and expression of MHC class II molecules, CD40, CD80, and CD86 was up-regulated. Importantly, secretion of cytokines as well as translocation of NF-κB were dependent on the presence of TLR2 and independent from TLR4 with the exception of IL-12p40 secretion, which was attenuated in the absence of either a functional TLR2 or 4. In conclusion, we show here that recognition of the Gram-negative bacterium C. pneumoniae depends largely on TLR2 and only to a minor extent on TLR4.