bluuebunny/crossref_metadata_2025 huggingface dataset:
IL-12p70 Production byLeishmania major-Harboring Human Dendritic Cells Is a CD40/CD40 Ligand-Dependent Process
Authors: Marovich Mary A. , McDowell Mary Ann , Thomas Elaine K. , Nutman Thomas B.
Published: April 2014

Leishmaniasis, a vector-borne parasitic disease, is transmitted during a sandfly blood meal as the parasite is delivered into the dermis. The parasite displays a unique immune evasion mechanism: prevention of IL-12 production within its host cell, the macrophage (i.e., where it differentiates and multiplies). Given the close proximity of skin dendritic cells (DC) to the site of parasite delivery, their critical role in initiating immune responses and the self-healing nature of Leishmania major (Lm) infection, we examined the interaction between myeloid-derived human DC and Lm metacyclic promastigotes (infectious-stage parasites) to model the early “natural” events of infection. We found that DC can take up Lm and, after this internalization, undergo changes in surface phenotype suggesting “maturation”. Despite the intracellular location of the parasite and resultant up-regulation of costimulatory and class II molecules, there was no detectable cytokine release by these Lm-harboring DC. However, using intracellular staining and flow cytometry to analyze cytokine production at the single-cell level, we found that Lm-harboring DC, but not monocytes, produce large amounts of IL-12p70 in a CD40 ligand (CD40L)-dependent manner. Finally, DC generated from mononuclear cells from patients with cutaneous leishmaniasis (Lm), once loaded with live metacyclic promastigotes, were found to reactivate autologous primed T lymphocytes and induce a CD40L-dependent IFN-γ response. Our results link the required CD40/CD40L interactions for healing with DC-derived IL-12p70 production and provide a mechanism to explain the genesis of a protective T cell-mediated response in the face of local immune evasion within the macrophage at the site of Leishmania delivery.
Secreted and Membrane-Associated Matrix Metalloproteinases of IL-2-Activated NK Cells and Their Inhibitors
Authors: Kim Myoung H. , Kitson Richard P. , Albertsson Per , Nannmark Ulf , Basse Per H. , Kuppen Peter J. K. , Hokland Marianne E. , Goldfarb Ronald H.
Published: April 2014

We have previously documented that rat IL-2-activated NK (A-NK) cells produce matrix metalloproteinase-2 (MMP-2) and MMP-9. In this study, we describe mouse A-NK cell-derived MMPs, including MT-MMPs, and also TIMPs. RT-PCR analysis from cDNA of mouse A-NK cells revealed mRNA for MMP-2, MMP-9, MMP-11, MMP-13, MT1-MMP, MT2-MMP, TIMP-1, and TIMP-2. MMP-2 and MMP-9 expression was confirmed by gelatin zymography. Moreover, we report for the first time that MT-MMPs are expressed by NK cells, i.e., large granular lymphocytes as determined by both RT-PCR and Western blots. TIMP-1 expression was detected as a 29-kDa protein in Western blots. It is intriguing that TIMP-2 protein from A-NK cells was also detected as a 29-kDa protein, which is clearly different from the previously reported molecular mass of 21 kDa in mouse and human cells. In addition, inhibition of MMPs by BB-94, a selective inhibitor of MMP, significantly inhibited the ability of mouse A-NK cells to migrate through Matrigel, a model basement membrane. Taken together, these findings suggest that A-NK cells may therefore use multiple MMPs in various cellular functions, including degradation of various extracellular matrix molecules as they extravasate from blood vessels and accumulate within cancer metastases following their adoptive transfer.
Vascular Endothelial Growth Factor Expression and Regulation of Murine Collagen-Induced Arthritis
Authors: Lu Jing , Kasama Tsuyoshi , Kobayashi Kazuo , Yoda Yoshiyuki , Shiozawa Fumitaka , Hanyuda Michio , Negishi Masao , Ide Hirotsugu , Adachi Mitsuru
Published: April 2014

We have examined the expression and function of the angiogenic factor, vascular endothelial growth factor (VEGF) during the evolution of type II collagen-induced arthritis (CIA). Biologically active VEGF was expressed along a time course that paralleled the expression of two specific VEGF receptors, Flk-1 and Flt-1, and the progression of joint disease. Moreover, levels of VEGF expression correlated with the degree of neovascularization, as defined by vWF levels, and arthritis severity. Macrophage- and fibroblast-like cells, which infiltrated inflamed sites and were then activated by other inflammatory mediators, are probably important sources of VEGF and may thus regulate angiogenesis during the development of CIA. Administration of anti-VEGF antiserum to CIA mice before the onset of arthritis delayed the onset, reduced the severity, and diminished the vWF content of arthritic joints. By contrast, administration of anti-VEGF antiserum after the onset of the disease had no effect on the progression or ultimate severity of the arthritis. These data suggest that VEGF plays a crucial role during an early stage of arthritis development, affecting both neovascularization and the progression of experimentally induced synovitis.
Molecular Mechanisms of Increased Nitric Oxide (NO) in Asthma: Evidence for Transcriptional and Post-Translational Regulation of NO Synthesis
Authors: Guo Fuhua H. , Comhair Suzy A. A. , Zheng Shuo , Dweik Raed A. , Eissa N. Tony , Thomassen Mary Jane , Calhoun William , Erzurum Serpil C.
Published: April 2014

Evidence supporting increased nitric oxide (NO) in asthma is substantial, although the cellular and molecular mechanisms leading to increased NO are not known. Here, we provide a clear picture of the events regulating NO synthesis in the human asthmatic airway in vivo. We show that human airway epithelium has abundant expression of NO synthase II (NOSII) due to continuous transcriptional activation of the gene in vivo. Individuals with asthma have higher than normal NO concentrations and increased NOSII mRNA and protein due to transcriptional regulation through activation of Stat1. NOSII mRNA expression decreases in asthmatics receiving inhaled corticosteroid, treatment effective in reducing inflammation in asthmatic airways. In addition to transcriptional mechanisms, post-translational events contribute to increased NO synthesis. Specifically, high output production of NO is fueled by a previously unsuspected increase in the NOS substrate, l-arginine, in airway epithelial cells of asthmatic individuals. Finally, nitration of proteins in airway epithelium provide evidence of functional consequences of increased NO. In conclusion, these studies define multiple mechanisms that function coordinately to support high level NO synthesis in the asthmatic airway. These findings represent a crucial cornerstone for future therapeutic strategies aimed at regulating NO synthesis in asthma.
Threshold Signaling of Human Th0 Cells in Activation and Anergy: Modulation of Effector Function by Altered TCR Ligand
Authors: Verhoef Adrienne , Lamb Jonathan R.
Published: April 2014

Molecular interactions between TCR and its natural ligand, in the presence of costimulatory signals, elicit T cell effector functions, whereas subtle changes in the structure of antigenic peptides may induce only selected T cell effector function including anergy. In this study, we have investigated the immunological activity of an altered TCR ligand (p 2, 28–40A34,36) derived from the immunodominant T cell epitope of the group 2 allergen of house dust mite, in which residues at positions 34 and 36 were substituted by alanine. Elevated IFN-γ synthesis was induced by equimolar concentrations of the analogue compared with native peptide (p 2, 28–40) and was paralleled by increased down-regulation of cell surface CD3. IL-5 and IL-10 production exhibit the same sensitivity to both peptides, implying that the induction of T cell effector functions are not all proportional to TCR occupancy. Both native peptide and the analogue bound to MHC class II (DRB1*1101) molecules with similar affinities. Furthermore, p 2, 28–40A34,36 induced T cell anergy at lower concentrations than native peptide. During the induction of anergy, TGF-β production was comparable for both peptides, whereas IL-10 secretion was markedly increased but more so in response to p 2, 28–40A34,36. Membrane expression of costimulatory ligands CD80 and CD86 was similar for native peptide and p 2, 28–40A34,36 and increased in activation, whereas only CD86 was elevated during anergy. The modulation of T cell effector function with altered TCR ligands may have practical applications in reprogramming allergic inflammatory responses through the induction of T cell anergy and/or the promotion of Th1 cytokines.
Cytolytic T Lymphocytes Raised Against a Human Bladder Carcinoma Recognize an Antigen Encoded by GeneMAGE-A12
Authors: Heidecker Leonora , Brasseur Francis , Probst-Kepper Michael , Guéguen Maryse , Boon Thierry , Van den Eynde Benoı̂t J.
Published: April 2014

Human bladder carcinoma line LB831-BLC expresses several distinct Ags that are recognized by different autologous CTL. Here, we show that one of these Ags is presented by HLA-Cw7 and encoded by gene MAGE-A12. This is the first time that CTL directed against a MAGE-encoded Ag have been derived from the lymphocytes of a patient with cancer other than melanoma. This new Ag was found to be nonapeptide VRIGHLYIL, corresponding to position 170–178 of the MAGE-A12 protein. Gene MAGE-A12 is silent in normal tissues except in male germline cells, which do not express HLA molecules. It is expressed in 26–62% of melanomas, infiltrating bladder carcinomas, lung carcinomas, esophageal carcinomas, and head and neck carcinomas. Because HLA-Cw7 is present in 43% of Caucasians, this new Ag is shared by many tumors and should be a useful target for cancer immunotherapy.
High Frequency of Autologous Anti-Melanoma CTL Directed Against an Antigen Generated by a Point Mutation in a New Helicase Gene
Authors: Baurain Jean-François , Colau Didier , van Baren Nicolas , Landry Claire , Martelange Valérie , Vikkula Miikka , Boon Thierry , Coulie Pierre G.
Published: April 2014

We have identified an Ag recognized by autologous CTL on the melanoma cells of a patient who enjoyed an unusually favorable clinical evolution. The antigenic peptide, which is presented by HLA-A28 molecules, is encoded by a mutated sequence in a new gene. This gene, which was named MUM-3, is expressed ubiquitously and shows homology with the RNA helicase gene family. Limiting dilution analysis indicated that at least 0.15% of the blood CD8 T cells were tumor-specific CTL precursors. The MUM-3 Ag was recognized by 90% of these CTL, indicating that it is the dominant target Ag of the tumor-specific CTL response. The high frequency of anti-MUM-3 CTL was confirmed with tetramers of soluble HLA-A28 molecules loaded with the antigenic peptide. MUM-3 tetramers stained 1.2% of blood CD8 cells, a frequency that has never been reported for T cells directed against a strictly tumor-specific Ag. To confirm these results, the CD8 T cells that were clearly labeled with tetramers were restimulated in clonal conditions. About 90% of these cells proliferated, and all the resulting clones proved lytic and MUM-3 specific. By improving the conditions used for the in vitro restimulation of CTL precursors by the tumor cells, the same frequency could be obtained in limiting dilution analysis. These results show that some cancer patients have a high frequency of circulating CTL that are directed against a strictly tumor-specific Ag. These CTL are responsive to restimulation in vitro and are easily detected with tetramers. Such responses may therefore be an achievable goal for therapeutic vaccination with tumor-specific Ags.
IL-18 Prevents the Development of Chronic Graft-Versus-Host Disease in Mice
Authors: Okamoto Iwao , Kohno Keizo , Tanimoto Tadao , Iwaki Kansou , Ishihara Tatsuya , Akamatsu Sachiko , Ikegami Hakuo , Kurimoto Masashi
Published: April 2014

The development of chronic graft-versus-host disease (GVHD), which is induced by the transfer of DBA/2 spleen cells into (C57BL/6 × DBA/2)F1 (BDF1) mice, is closely related to diminished donor anti-host CTL activity and host B cell hyperactivation. Therefore, an approach which activates donor CD8+ T cells or suppresses donor CD4+ T cell-host B cell interaction may have clinical utility in the treatment of chronic GVHD. We have previously demonstrated that IL-18 induces the development of naive CD8+ T cells into type I effector cells in DBA/2 anti-BDF1 MLC. In this paper we examined the effect of IL-18 administration on the development of chronic GVHD in mice. The treatment was started before or after the onset of clinical evidence of the disease. Regardless of the treatment schedule, IL-18 significantly decreased immunological parameters indicative of chronic GVHD, such as elevated serum IgG antinuclear Abs, IgG1, and IgE levels, and host B cell numbers and their activation. Importantly, IL-18-treated mice did not show the same acute GVHD-like symptoms reported for IL-12 treatment, because there was no weight loss, death, or severe immunodeficiency as indicated by a decrease in IL-2 and IFN-γ production by Con A-stimulated spleen cells. In contrast, IL-18 treatment partially but significantly restored the production of these cytokines. Data further suggested that these IL-18-mediated therapeutic effects may be due to the induction of donor CD8+ CTL, the decrease in donor CD4+ T cell numbers, and a down-regulation of host B cell MHC class II expression. Thus, our results suggest that IL-18 has beneficial effects in the prevention and treatment of chronic GVHD.
Cutting Edge: T Cell-Mediated Pathology in Murine Lyme Borreliosis
Authors: McKisic Maureen D. , Redmond William L. , Barthold Stephen W.
Published: April 2014

Even in the absence of an appropriate model or direct evidence, T cells have been hypothesized to exacerbate the manifestations of Lyme disease. To define definitely the role of T cells in Lyme disease, the course of disease in immunocompetent and B cell-deficient mice was compared. By 8 wk postinoculation, immunocompetent mice resolved both carditis and arthritis, whereas foci of myocarditis and severe destructive arthritis characterized disease of B cell-deficient mice. Cell transfer experiments using infected B6-Rag1 knock out mice demonstrated that: 1) innate immunity mediated the initial sequelae of infection, 2) transferring both naive T cells and B cells induced resolution of carditis and arthritis, 3) infected mice reconstituted with T cells developed myocarditis and severe destructive arthritis, and 4) CD4+ T cells were responsible for the observed immune-mediated pathology. These data demonstrate directly the deleterious effect of T cells in Lyme disease.
Cutting Edge: Soluble HLA-G1 Triggers CD95/CD95 Ligand-Mediated Apoptosis in Activated CD8+ Cells by Interacting with CD8
Authors: Fournel Sylvie , Aguerre-Girr Maryse , Huc Xavier , Lenfant Françoise , Alam Antoine , Toubert Antoine , Bensussan Armand , Le Bouteiller Philippe
Published: April 2014

The nonpolymorphic soluble HLA-G1 (sHLA-G1) isoform has been reported to be secreted by trophoblast cells at the materno-fetal interface, suggesting that it may act as immunomodulator during pregnancy. In this paper, we report that affinity-purified β2-microglobulin-associated sHLA-G1 triggered apoptosis in activated, but not resting CD8+ peripheral blood cells. We demonstrate by Western blotting that sHLA-G1 enhanced CD95 ligand expression in activated CD8+ cells. Cytotoxicity was inhibited by preincubation of the cells with a CD95 antagonist mAb (ZB4) or a soluble recombinant CD95-Fc, indicating that apoptosis is mediated through the CD95/CD95 ligand pathway. Finally, we show that such sHLA-G1-induced apoptosis depends on the interaction with CD8 molecules, with cell death being blocked by various CD8 mAbs.
Analysis of Soluble and Cell Surface Factors Regulating Anti-DNA Topoisomerase I Autoantibody Production Demonstrates Synergy Between Th1 and Th2 Autoreactive T Cells
Authors: Kuwana Masataka , Medsger Thomas A. , Wright Timothy M.
Published: April 2014

The cellular and subcellular events governing Ab production with specificity for self Ags are poorly understood. In this study we examined the role of cellular interactions and cytokines in regulating the production of anti-DNA topoisomerase I (topo I) Ab, a major autoantibody in patients with systemic sclerosis (SSc). Topo I-specific T cell clones derived from SSc subjects and healthy donors were cultured with autologous peripheral blood B cells. Anti-topo I Ab production was induced by five of seven topo I-specific T cell clones derived from SSc subjects, but by none of eight T cell clones generated from healthy controls. However, two of the T cell clones from healthy controls provided help to HLA-DR-matched SSc B cells to produce anti-topo I Ab. The analysis of cytokine mRNA expression revealed that the ability to promote anti-topo I autoantibody production was strictly correlated with IL-2 and IL-6 expression by the T cell clones. Kinetic studies showed that IL-2 was required throughout the culture period for maximal autoantibody production and that both MHC-TCR and CD40-CD40L interactions were essential during the early phase of the culture. IL-6 was important in the late phase. Th1 clones (producing IL-2, but no IL-6) and Th2 clones (producing IL-6, but no IL-2) synergically activated autologous B cells to produce anti-topo I Ab. These results indicate that T cell-dependent B cell activation resulting in anti-topo I autoantibody production requires a series of temporally defined cell contact and soluble stimuli.
Monocyte Chemoattractant Protein-1 Enhances Gene Expression and Synthesis of Matrix Metalloproteinase-1 in Human Fibroblasts by an Autocrine IL-1α Loop
Authors: Yamamoto Toshiyuki , Eckes Beate , Mauch Cornelia , Hartmann Karin , Krieg Thomas
Published: April 2014

Monocyte chemoattractant protein-1 (MCP-1), a member of the C-C chemokine superfamily, has recently been shown to be involved in the pathogenesis of tissue fibrosis. In vitro studies demonstrated that MCP-1 up-regulates type I collagen gene expression via endogenous production of TGF-β in rat lung fibroblasts. We here show that recombinant human MCP-1 affects gene expression of interstitial collagenase (matrix metalloproteinase-1 (MMP-1)) in primary human skin fibroblasts and a stable fibroblast cell line. MMP-1 mRNA was induced by MCP-1 (10 ng/ml) as early as 6 h and reached a maximal expression at 24 h. MCP-1 also caused an increase of MMP-2 mRNA expression in both types of fibroblasts at 48 h. Interestingly, tissue inhibitor of metalloproteinase-1 (TIMP-1) mRNA was also up-regulated by MCP-1, and TIMP-1 mRNA expression peaked at 48 h in both types of fibroblasts. Immunoblot analysis demonstrated increased levels of MMP-1 and TIMP-1 protein in the culture supernatants of primary fibroblasts stimulated with MCP-1. In addition, MCP-1 strongly induced IL-1α mRNA expression in dermal fibroblasts in parallel with the induction of MMP-1. Preincubation with IL-1 receptor antagonist almost completely abrogated the expression of MMP-1 mRNA, and partially inhibited MMP-1 synthesis induced by MCP-1. Transient transfection of primary skin fibroblasts with a MMP-1 promoter-reporter construct indicated a dose-dependent increase in promoter activity by MCP-1 stimulation. These data demonstrate that MCP-1 up-regulates MMP-1 mRNA expression and synthesis in human skin fibroblasts at a transcriptional level and provide evidence that this is mediated by an IL-1α autocrine loop.
Proliferating Cell Nuclear Antigen as the Cell Cycle Sensor for an HLA-Derived Peptide Blocking T Cell Proliferation
Authors: Ling Xuefeng , Kamangar Salar , Boytim Michelle L. , Kelman Zvi , Huie Philip , Lyu Shu-Chen , Sibley Richard K. , Hurwitz Jerard , Clayberger Carol , Krensky Alan M.
Published: April 2014

Synthetic peptides corresponding to structural regions of HLA molecules are novel immunosuppressive agents. A peptide corresponding to residues 65–79 of the α-chain of HLA-DQA03011 (DQ65–79) blocks cell cycle progression from early G1 to the G1 restriction point, which inhibits cyclin-dependent kinase-2 activity and phosphorylation of the retinoblastoma protein. A yeast two-hybrid screen identified proliferating cell nuclear Ag (PCNA) as a cellular ligand for this peptide, whose interaction with PCNA was further confirmed by in vitro biochemistry. Electron microscopy demonstrates that the DQ65–79 peptide enters the cell and colocalizes with PCNA in the T cell nucleus in vivo. Binding of the DQ65–79 peptide to PCNA did not block polymerase δ (pol δ)-dependent DNA replication in vitro. These findings support a key role for PCNA as a sensor of cell cycle progression and reveal an unanticipated function for conserved regions of HLA molecules.
Reverse Signaling Through Transmembrane TNF Confers Resistance to Lipopolysaccharide in Human Monocytes and Macrophages
Authors: Eissner Günther , Kirchner Silvia , Lindner Heidrun , Kolch Walter , Janosch Petra , Grell Matthias , Scheurich Peter , Andreesen Reinhard , Holler Ernst
Published: April 2014

We have previously reported that the CD14+ monocytic subpopulation of human PBMC induces programmed cell death (apoptosis) in cocultured endothelial cells (EC) when stimulated by bacterial endotoxin (LPS). Apoptosis is mediated by two routes, first via transmembrane TNF-α (mTNF) expressed on PBMC and, in addition, by TNF-independent soluble factors that trigger apoptosis in EC. Neutralizing anti-TNF mAb completely blocked coculture-mediated apoptosis, despite the fact that there should have been additional soluble cell death factors. This led to the hypothesis that a reverse signal is transmitted from the TNF receptor on EC to monocytes (MO) via mTNF that prevents the production of soluble apoptotic factors. Here we have tested this hypothesis. The results support the idea of a bidirectional cross-talk between MO and EC. Peripheral blood MO, MO-derived macrophages (MΦ), or the monocytic cell line Mono Mac 6 were preincubated with human microvascular EC that constitutively express TNF receptor type I (TNF-R1) and subsequently stimulated with LPS. Cell-free supernatants of these preparations no longer induced EC apoptosis. The preincubation of MO/MΦ with TNF-reactive agents, such as mAb and soluble receptors, also blocked the production of death factors, providing further evidence for reverse signaling via mTNF. Finally, we show that reverse signaling through mTNF mediated LPS resistance in MO/MΦ as indicated by the down-regulation of LPS-induced soluble TNF and IL-6 as well as IL-1 and IL-10.
Transcription-Coupled and Global Genome Repair Differentially Influence UV-B-Induced Acute Skin Effects and Systemic Immunosuppression
Authors: Garssen Johan , van Steeg Harry , de Gruijl Frank , de Boer Jan , van der Horst Gijsbertus T. J. , van Kranen Henk , van Loveren Henk , van Dijk Mariska , Fluitman Angelique , Weeda Geert , Hoeijmakers Jan H. J.
Published: April 2014

Exposure to UV-B radiation impairs immune responses in mammals by inhibiting especially Th1-mediated contact hypersensitivity and delayed-type hypersensitivity. Immunomodulation is not restricted to the exposed skin, but is also observed at distant sites, indicating the existence of mediating factors such as products from exposed skin cells or photoactivated factors present in the superficial layers. DNA damage appears to play a key role, because enhanced nucleotide excision repair (NER) strongly counteracts immunosuppression. To determine the effects of the type and genomic location of UV-induced DNA damage on immunosuppression and acute skin reactions (edema and erythema) four congenic mouse strains carrying different defects in NER were compared: CSB and XPC mice lacking transcription-coupled or global genome NER, respectively, as well as XPA and TTD/XPD mice carrying complete or partial defects in both NER subpathways, respectively. The major conclusions are that 1) transcription-coupled DNA repair is the dominant determinant in protection against acute skin effects; 2) systemic immunomodulation is only affected when both NER subpathways are compromised; and 3) sunburn is not related to UV-B-induced immunosuppression.
Sustained Expression of CD154 (CD40L) and Proinflammatory Cytokine Production by Alloantigen-Stimulated Umbilical Cord Blood T Cells
Authors: Matthews Nick C. , Wadhwa Meenu , Bird Chris , Borras Francesc E. , Navarrete Cristina V.
Published: April 2014

Recent data suggests that graft-versus-host disease (GVHD) is initiated by host APCs. Blockade of CD40:CD154 interactions between APCs and T cells in vivo induces T cell tolerance to host alloantigen and dramatically reduces GVHD. Because allogeneic cord blood (CB) transplantation results in a lower incidence and severity of acute GVHD compared with bone marrow transplantation, we have investigated whether CB T cells can express CD154 in response to stimulation by allogeneic monocyte-derived dendritic cells (MDDC) and have used 5- (and 6-)carboxyfluorescein diacetate succinimidyl ester (CFSE) labeling in combination with intracellular cytokine analysis to assess the proliferation and cytokine profiles of alloantigen-responsive cells. CB T cells stimulated with allogeneic MDDC showed stronger proliferation than adult blood T cells. Surface CD154 expression was detected in the actively dividing CFSElow populations of both the CD4+ and CD4− subsets and was brightest in cells that had divided the most. Assessment of supernatants from MDDC-stimulated CB and adult blood T cells showed no significant difference in the levels of either IFN-γ or TNF-α, but CB T cell supernatants did show a significant lack of detectable IL-2. Intracellular cytokine analysis revealed that dividing CB T cells had been primed to produce IFN-γ, TNF-α, and IL-2 on restimulation. Further phenotype analysis showed that 75% of CB T cells producing IFN-γ were CD8+. These data suggest that MDDC-stimulated CB T cells express functional CD154 and provide enough costimulation for dendritic cells to prime naive CD8+ CB T cells and induce type 1 cytokine production.
Glucocorticoids Regulate TCR-Induced Elevation of CD4: Functional Implications
Authors: Wiegers G. Jan , Stec Ilona E. M. , Klinkert Wolfgang E. F. , Reul Johannes M. H. M.
Published: April 2014

CD4 serves as a coreceptor during Ag recognition by the TCR. This interaction results in a marked increase in the sensitivity of a T cell to Ag presented by MHC class II molecules. Here we report that activation of T cells either by plate-bound mAb (anti-TCR, anti-CD3) or soluble activators (staphylococcal enterotoxin A, Con A) is associated with an (up to 3-fold) increase in CD4 cell surface expression on CD25+ cells, which was maximal after 72–96 h. Incubation with the glucocorticoid hormone corticosterone (CORT) shifted the enhancement of CD4 expression to a point about 24 h earlier than that observed in control cultures. In parallel, the proliferative response of these CORT-treated cells was profoundly enhanced. An involvement of increased CD4 expression in this enhanced proliferative response was evidenced by the observation that T cell proliferation in CORT-treated cultures was much less sensitive to inhibition by an inhibitory, nondepleting anti-CD4 mAb than that in control cultures. TCR down-regulation was, however, not affected by CORT. Thus, based on this study and previous reports we propose that both TCR-mediated signals and glucocorticoids are important physiological regulators of CD4 expression. In addition, these findings may be of significance for the sensitivity of CD4+ cells to HIV infection upon T cell activation, as the efficacy of primary patient HIV entry depends on the level of surface CD4.
Analysis of the Diversity of a Sheep Antibody Repertoire as Revealed from a Bacteriophage Display Library
Authors: Charlton Keith A. , Moyle Sarah , Porter Andrew J. R. , Harris William J.
Published: April 2014

We have applied bacteriophage display technology to construct and analyze the diversity of an IgG library of >1 × 108 clones from an adult sheep immunized against the hapten atrazine. We have identified eight new VH gene families (VH2–VH9) and five new Vκ gene families (VκV–VκIX). The heavy and κ light chain variable region gene loci were found to be far more diverse than previously thought.
IL-2 Activation of NK Cells: Involvement of MKK1/2/ERK But Not p38 Kinase Pathway
Authors: Yu Tse-Kuan , Caudell Eva G. , Smid Christine , Grimm Elizabeth A.
Published: April 2014

IL-2 stimulates extracellular signal-regulated protein kinase (ERK) and p38 mitogen-activated protein kinase (MAPK) in various immune cell populations. The functional roles that these kinases play are still unclear. In this study, we examined whether MAPK kinase (MKK)/ERK and p38 MAPK pathways are necessary for IL-2 to activate NK cells. Using freshly isolated human NK cells, we established that an intact MKK/ERK pathway is necessary for IL-2 to activate NK cells to express at least four known biological responses: LAK generation, IFN-γ secretion, and CD25 and CD69 expression. IL-2 induced ERK activation within 5 min. Treatment of NK cells with a specific inhibitor of MKK1/2, PD98059, during the IL-2 stimulation blocked in a dose-dependent manner each of four sequelae, with inhibition of lymphokine-activated killing induction being least sensitive to MKK/ERK pathway blockade. Activation of p38 MAPK by IL-2 was not detected in NK cells. In contrast to what was observed by others in T lymphocytes, SB203850, a specific inhibitor of p38 MAPK, did not inhibit IL-2-activated NK functions. This data indicate that p38 MAPK activation was not required for IL-2 to activate NK cells for the four functions examined. These results reveal selective signaling differences between NK cells and T lymphocytes; in NK cells, the MKK/ERK pathway and not p38 MAPK plays a critical positive regulatory role during activation by IL-2.
The ADP-Ribosylating CTA1-DD Adjuvant Enhances T Cell-Dependent and Independent Responses by Direct Action on B Cells Involving Anti-Apoptotic Bcl-2- and Germinal Center-Promoting Effects
Authors: Ågren Lena , Sverremark Eva , Ekman Lena , Schön Karin , Löwenadler Björn , Fernandez Carmen , Lycke Nils
Published: April 2014

We recently developed a novel immunomodulating gene fusion protein, CTA1-DD, that combines the ADP-ribosylating ability of cholera toxin (CT) with a dimer of an Ig-binding fragment, D, of Staphylococcus aureus protein A. The CTA1-DD adjuvant was found to be nontoxic and greatly augmented T cell-dependent responses to soluble protein Ags after systemic as well as mucosal immunizations. Here we show that CTA1-DD does not appear to form immune complexes or bind to soluble Ig following injections, but, rather, it binds directly to B cells of all isotypes, including naive IgD+ cells. No binding was observed to macrophages or dendritic cells. Immunizations in FcεR (common FcRγ-chain)- and FcγRII-deficient mice demonstrated that CTA1-DD exerted unaltered enhancing effects, indicating that FcγR-expressing cells are not required for the adjuvant function. Whereas CT failed to augment Ab responses to high m.w. dextran B512 in athymic mice, CTA1-DD was highly efficient, demonstrating that T cell-independent responses were also enhanced by this adjuvant. In normal mice both CT and CTA1-DD, but not the enzymatically inactive CTA1-R7K-DD mutant, were efficient enhancers of T cell-dependent as well as T cell-independent responses, and both promoted germinal center formation following immunizations. Although CT augmented apoptosis in Ag receptor-activated B cells, CTA1-DD strongly counteracted apoptosis by inducing Bcl-2 in a dose-dependent manner, a mechanism that was independent of the CD19 coreceptor. However, in the presence of CD40 stimulation, apoptosis was low and unaffected by CT, suggesting that the adjuvant effect of CT is dependent on the presence of activated CD40 ligand-expressing T cells.
Vitamin D3 Up-Regulated Protein 1 Mediates Oxidative Stress Via Suppressing the Thioredoxin Function
Authors: Junn Eunsung , Han Seung Hyun , Im Joo Young , Yang Young , Cho Eun Wie , Um Hong Duck , Kim Do Kyun , Lee Kang Woo , Han Pyung Lim , Rhee Sue Goo , Choi Inpyo
Published: April 2014

As a result of identifying the regulatory proteins of thioredoxin (TRX), a murine homologue for human vitamin D3 up-regulated protein 1 (VDUP1) was identified from a yeast two-hybrid screen. Cotransfection into 293 cells and precipitation assays confirmed that mouse VDUP1 (mVDUP1) bound to TRX, but it failed to bind to a Cys32 and Cys35 mutant TRX, suggesting the redox-active site is critical for binding. mVDUP1 was ubiquitously expressed in various tissues and located in the cytoplasm. Biochemical analysis showed that mVDUP1 inhibited the insulin-reducing activity of TRX. When cells were treated with various stress stimuli such as H2O2 and heat shock, mVDUP1 was significantly induced. TRX is known to interact with other proteins such as proliferation-associated gene and apoptosis signal-regulating kinase 1. Coexpression of mVDUP1 interfered with the interaction between TRX and proliferation-associated gene or TRX and ASK-1, suggesting its roles in cell proliferation and oxidative stress. To investigate the roles of mVDUP1 in oxidative stress, mVDUP1 was overexpressed in NIH 3T3 cells. When cells were exposed to stress, cell proliferation was declined with elevated apoptotic cell death compared with control cells. In addition, c-Jun N-terminal kinase activation and IL-6 expression were elevated. Taken together, these results demonstrate that mVDUP1 functions as an oxidative stress mediator by inhibiting TRX activity.
Mice with a Selective Deletion of the CC Chemokine Receptors 5 or 2 Are Protected from Dextran Sodium Sulfate-Mediated Colitis: Lack of CC Chemokine Receptor 5 Expression Results in a NK1.1+ Lymphocyte-Associated Th2-Type Immune Response in the Intestine
Authors: Andres Pietro G. , Beck Paul L. , Mizoguchi Emiko , Mizoguchi Atsushi , Bhan Atul K. , Dawson Tracey , Kuziel William A. , Maeda Nobuyo , MacDermott Richard P. , Podolsky Daniel K. , Reinecker Hans-Christian
Published: April 2014

The chemokine receptors CCR2 and CCR5 and their respective ligands regulate leukocyte chemotaxis and activation. To determine the role of these chemokine receptors in the regulation of the intestinal immune response, we induced colitis in CCR2- and CCR5-deficient mice by continuous oral administration of dextran sodium sulfate (DSS). Both CCR2- and CCR5-deficient mice were susceptible to DSS-induced intestinal inflammation. The lack of CCR2 or CCR5 did not reduce the DSS-induced migration of macrophages into the colonic lamina propria. However, both CCR5-deficient mice and, to a lesser degree, CCR2-deficient mice were protected from DSS-induced intestinal adhesions and mucosal ulcerations. CCR5-deficient mice were characterized by a greater relative infiltration of CD4+ and NK1.1+ lymphocyte in the colonic lamina propria when compared to wild-type and CCR2-deficient mice. In CCR5-deficient mice, mucosal mRNA expression of IL-4, IL-5, and IL-10 was increased, whereas that of IFN-γ was decreased, corresponding to a Th2 pattern of T cell activation. In CCR2-deficient mice, the infiltration of Th2-type T cells in the lamina propria was absent, but increased levels of IL-10 and decreased levels of IFN-γ may have down regulated mucosal inflammation. Our data indicate that CCR5 may be critical for the promotion of intestinal Th1-type immune responses in mice.
Genetic Immunization with Lung-Targeting Macroaggregated Polyethyleneimine-Albumin Conjugates Elicits Combined Systemic and Mucosal Immune Responses
Authors: Orson Frank M. , Kinsey Berma M. , Hua Pascal J. , Bhogal Balbir S. , Densmore Charles L. , Barry Michael A.
Published: April 2014

Genetic immunization is a novel form of vaccination in which transgenes are delivered into the host to produce the foreign protein within host cells. Although systemic immune responses have been relatively easy to induce by genetic immunization, the induction of regional and mucosal immunity has often been more challenging. To address the problem of eliciting mucosal immunity in the lung, we utilized macroaggregated albumin to target plasmid DNA to the lung. Macroaggregated albumin is trapped in the lung after i.v. injection, and it is routinely used in radiolabeled form as an imaging modality to evaluate pulmonary blood flow. To couple DNA to this targeting agent, polyethyleneimine (a polycation that binds DNA and enhances transfection) was conjugated to serum albumin, and the conjugate was aggregated by heating to produce particles of 25–100 μm. The resulting particles bound plasmid DNA avidly, and when injected i.v. in mice, the particles distributed in the peripheral lung tissue in the alveolar interstitium. Particle-bound luciferase plasmid transfected a variety of cell lines in vitro, and after i.v. injection, gene expression was detected exclusively in the lung. Using human growth hormone as the encoded foreign Ag for immunization, i.v. injection of the particle-bound plasmid elicited both pulmonary mucosal and systemic immune responses, whereas naked DNA injected either i.v. or i.m. elicited only systemic responses. Thus, particle-bound plasmid DNA may have utility for genetic immunization by intravascular delivery to the lung and potentially to other organs and tissues.
Functional Analysis of the Murine TCRβ-Chain Gene Enhancer
Authors: Carvajal Irvith M. , Sen Ranjan
Published: April 2014

The TCRβ-chain gene enhancer activates transcription and V(D)J recombination in immature thymocytes. In this paper we present a systematic analysis of the elements that contribute to the activity of the murine TCRβ enhancer in mature and immature T cell lines. We identified a region containing the βE4, βE5, and βE6 motifs as the essential core of the TCRβ enhancer in pro-T cells. In mature cells, the core enhancer had low activity and required, in addition, either 5′ or 3′ flanking sequences whose functions may be partially overlapping. Mutation of any of the six protein binding sites located within the βE4–βE6 elements essentially abolished enhancer activity, indicating that this core enhancer contained no redundant elements. The βE4 and βE6 elements contain binding sites for ETS-domain proteins and the core binding factor. The βE5 element bound two proteins that could be resolved chromatographically and that were both essential for enhancer activity.
Primary Structure and Functional Characterization of a Soluble, Alternatively Spliced Form of B7-1
Authors: Faas Susan J. , Giannoni Michelle A. , Mickle Angela P. , Kiesecker Cheri L. , Reed Deborah J. , Wu Dayang , Fodor William L. , Mueller John P. , Matis Louis A. , Rother Russell P.
Published: April 2014

Recent studies have suggested that soluble forms of B7-1 and B7-2 may exist, but transcripts that code for these molecules have not been previously described. In this study, we report the cloning and characterization of an alternatively spliced soluble form of porcine B7-1 (sB7-1) that lacks exons coding for both the transmembrane and cytoplasmic domains. Northern blot analysis of RNA from alveolar macrophages revealed an approximate 3:1 ratio of the transmembrane form of B7-1 mRNA relative to sB7-1 mRNA. Porcine B7-1 was present on the surface of both B and T cells following stimulation with PMA/ionomycin. A histidine-tagged form of porcine sB7-1 (sB7-1-His) interacted with both CD28 and CTLA-4, and effectively blocked IL-2 production from human responder cells stimulated with PHA and either porcine or human stimulator cells. In addition, sB7–1-His inhibited human T cell proliferation in response to porcine or human peripheral blood leukocytes. This study is the first report of an alternatively spliced form of B7 that codes for a soluble protein. Furthermore, these data demonstrate that porcine B7-1 interacts with the human receptors CD28 and CTLA-4, suggesting a potential role for this molecule in pig to human xenotransplantation. Possible physiological functions for the soluble form of B7-1 are discussed.
Functional Analysis of the OCA-B Promoter
Authors: Stevens Sean , Wang Lu , Roeder Robert G.
Published: April 2014

OCA-B was identified as a B cell-specific coactivator that functions with either Oct-1 or Oct-2 to mediate efficient cell type-specific transcription via the octamer site (ATGCAAAT) both in vivo and in vitro. Mice lacking OCA-B exhibit normal Ag-independent B cell maturation. In contrast, Ag-dependent functions, including production of secondary Ig isotypes and germinal center formation, are greatly affected. To better understand OCA-B expression and, ultimately, the defects observed in the OCA-B knockout mice, we have cloned the OCA-B promoter and examined its function in both transformed and primary B cells. We show here that the OCA-B promoter is developmentally regulated, with activity increasing throughout B cell differentiation. Through physical and functional assays, we have found an activating transcription factor/cAMP response element binding protein binding site (or cAMP response element) that is crucial for OCA-B promoter activity. Furthermore, we demonstrate that IL-4 and anti-CD40 induce both the OCA-B promoter and octamer-dependent promoters, thus implicating OCA-B in B cell signaling events in the nucleus.
Regulation of Germline Promoters by the Two Human Ig Heavy Chain 3′ α Enhancers
Authors: Hu Yanzhong , Pan Qiang , Pardali Evangelia , Mills Frederick C. , M. Bernstein Ralph , Max Edward E. , Sideras Paschalis , Hammarström Lennart
Published: April 2014

The human IgH 3′ enhancers, located downstream of each of the two Cα genes, modulate germline (GL) transcription of the IgH genes by influencing the activity of promoter-enhancer complexes upstream of the switch and intervening (I) regions. The regulation of GL α1 and α2 promoters by different human 3′ enhancer fragments was investigated in cell lines representing various developmental stages. Both α1HS1,2 and α2HS1,2 fragments show equally strong enhancer activity on the GL α1 and α2 promoters in both orientations when transiently transfected into a number of mature B cell line (DG75, CL-01, and HS Sultan). However, there is no activity in a human pre-B cell line (NALM-6) nor a human T cell line (Jurkat). HS3 shows no enhancer activity by itself in any of the cell lines, whereas a modest effect is noted using HS4 in the three mature B cell lines. However, the combination of the α2HS3-HS1,2-HS4 fragments, which together form a potential locus control region, displays a markedly stronger enhancer activity than the individual fragments with a differential effect on the α1 and α2 promoters as compared with the γ3 promoter. Our results suggest that the human GL α promoter may be regulated by two independent pathways. One pathway is induced by TGF-β1 which directs IgA isotype switch through activation of the GL α promoter and no TGF-β1-responsive elements are present in the different 3′ enhancer fragments. The other route is through the human 3′ enhancer regions that cis-up-regulate the GL α promoter activity in mature B cells.
Evidence That Terminal Deoxynucleotidyltransferase Expression Plays a Role in Ig Heavy Chain Gene Segment Utilization
Authors: Tuaillon Nadine , Capra J. Donald
Published: April 2014

TdT is a nuclear enzyme that catalyzes the addition of random nucleotides at Ig and TCR V(D)J junctions. In this paper we analyze human IgH rearrangements generated from transgenic minilocus mice in the presence or absence of TdT. In the absence of TdT, the pseudo-VH gene segment present in the minilocus is rearranged dramatically more frequently. Additionally, JH6 gene segment utilization is increased as well as the number of rearrangements involving only VH and JH gene segments. Thus, the recombination of IgH gene segments that are flanked by 23-nt spacer recombination signal sequences may be influenced by TdT expression. Extensive analysis indicates that these changes are independent of antigenic selection and cannot be explained by homology-mediated recombination. Thus, the role played by TdT may be more extensive than previously thought.
The Structure and Stability of an HLA-A*0201/Octameric Tax Peptide Complex with an Empty Conserved Peptide-N-Terminal Binding Site
Authors: Khan Amir R. , Baker Brian M. , Ghosh Partho , Biddison William E. , Wiley Don C.
Published: April 2014

The crystal structure of the human class I MHC molecule HLA-A2 complexed with of an octameric peptide, Tax8 (LFGYPVYV), from human T cell lymphotrophic virus-1 (HTLV-1) has been determined. This structure is compared with a newly refined, higher resolution (1.8 Å) structure of HLA-A2 complexed with the nonameric Tax9 peptide (LLFGYPVYV) with one more N-terminal residue. Despite the absence of a peptide residue (P1) bound in the conserved N-terminal peptide-binding pocket of the Tax8/HLA-A2 complex, the structures of the two complexes are essentially identical. Water molecules in the Tax8 complex replace the terminal amino group of the Tax9 peptide and mediate a network of hydrogen bonds among the secondary structural elements at that end of the peptide-binding groove. Thermal denaturation measurements indicate that the Tax8 complex is much less stable, ΔTm = 16°C, than the Tax9 complex, but both can sensitize target cells for lysis by some Tax-specific CTL from HTLV-1 infected individuals. The absence of a P1 peptide residue is thus not enough to prevent formation of a “closed conformation” of the peptide-binding site. TCR affinity measurements and cytotoxic T cell assays indicate that the Tax8/HLA-A2 complex does not functionally cross-react with the A6-TCR-bearing T cell clone specific for Tax9/HLA-A2 complexes.
IL-10 and the Dangers of Immune Polarization: Excessive Type 1 and Type 2 Cytokine Responses Induce Distinct Forms of Lethal Immunopathology in Murine Schistosomiasis
Authors: Hoffmann Karl F. , Cheever Allen W. , Wynn Thomas A.
Published: April 2014

To dissect the controversial roles of type 1 and type 2 cytokines to the pathogenesis of schistosomiasis, we generated IL-10/IL-4- and IL-10/IL-12-deficient mice that develop highly polarized type 1 and type 2 cytokine responses, respectively. Interestingly, the Th1-polarized IL-10/IL-4-deficient mice rapidly lost weight at the onset of egg-laying and displayed 100% mortality by wk 9 postinfection. This acute mortality was linked to overexpression of the proinflammatory mediators IFN-γ, TNF-α, and inducible NO and the formation of nonfibrotic granulomas. Elevated serum aspartate transaminase levels confirmed that mortality was in part attributable to acute hepatotoxicity. In contrast, the Th2-polarized IL-10/IL-12-deficient mice developed a progressive wasting disease that correlated with increased hepatic fibrosis, formation of large eosinophil-rich granulomas, a 10-fold increase in IL-4 and IL-13, and significant mortality during the chronic stages of infection. Surprisingly, IL-10-deficient mice displayed pathological features that were characteristic of both extremes, while wild-type mice developed relatively successful long term chronic infections. These data demonstrate that IL-10 significantly suppresses type 1 and type 2 cytokine development in IL-4- and IL-12-deficient mice, respectively, thereby impeding the development of severe egg-induced pathology in the single cytokine-deficient animals. Together, these findings reveal the central regulatory role of IL-10 in the pathogenesis of schistosomiasis and illustrate that excessive type 1 and type 2 cytokine responses trigger distinct, but equally detrimental, forms of pathology following infection.