bluuebunny/crossref_metadata_2025_split huggingface dataset:
Opsonization with C1q and Mannose-Binding Lectin Targets Apoptotic Cells to Dendritic Cells
Authors: Nauta Alma J. , Castellano Giuseppe , Xu Wei , Woltman Andrea M. , Borrias Maria C. , Daha Mohamed R. , van Kooten Cees , Roos Anja 
Published: April 2014

AbstractDeficiencies of early components of the classical complement pathway, particularly C1q, are strongly associated with susceptibility to systemic lupus erythematosus. Recent data link this predisposal to autoimmunity to an inappropriate clearance of apoptotic cells, which could lead to a loss of self-tolerance. In the present study, we demonstrate that opsonization of apoptotic cells with C1q and mannose-binding lectin allows and facilitates their uptake not only by macrophages but also by human immature dendritic cells (DCs). Both C1q and mannose-binding lectin enhance the uptake of apoptotic cells by DCs in a dose-dependent way. The uptake of C1q-opsonized apoptotic cells, but not nonopsonized apoptotic cells, by DCs stimulated the production of IL-6, IL-10, and TNF-α, without an effect on IL-12p70. We conclude that these recognition molecules of the complement system do not sequester apoptotic cells from DCs, but rather promote their uptake by immature DCs. Therefore, we propose that early complement components support safe clearance of cellular debris by facilitating phagocytosis and possibly by immunomodulatory mechanisms, thus preventing autoimmunity.
Identification and Characterization of pDC-Like Cells in Normal Mouse Skin and Melanomas Treated with Imiquimod
Authors: Palamara Francesca , Meindl Simone , Holcmann Martin , Lührs Petra , Stingl Georg , Sibilia Maria 
Published: April 2014

Abstract
Among the different subsets of dendritic cells (DC) described in humans and mice, epidermal Langerhans cells and dermal DCs represent the only DC populations resident in normal skin. In this study we describe a population of CD4+CD3− plasmacytoid DC (pDC)-like cells that accumulate in the dermis and spleens of mice topically treated with imiquimod, a low m.w. immune response modifier with potent antiviral and antitumor activities. These CD4+CD3− cells coexpress GR-1, B220, MHC class II, and, to a lesser extent, CD11c and display the phenotypic features of pDCs described in lymphoid organs. The accumulation of pDC-like cells after imiquimod treatment was detected not only in normal skin, but also in intradermally induced melanomas. Imiquimod treatment leads either to complete regression or to a significant reduction of the tumors. The number of pDCs correlates well with the clinical response of the tumors to the drug, suggesting that the antitumor effects of imiquimod could be mediated at least in part by the recruitment of pDC-like cells to the skin. Therefore, strategies aimed at activating and directing these cells into neoplastic tissues may be a promising and novel approach for the immunotherapy of various types of cancer.
An Evaluation of Enforced Rapid Proteasomal Degradation as a Means of Enhancing Vaccine-Induced CTL Responses
Authors: Wong S. B. Justin , Buck Christopher B. , Shen Xuefei , Siliciano Robert F. 
Published: April 2014

AbstractThe HIV-1 Gag protein is an attractive target for CTL-based vaccine strategies because it shows less sequence variability than other HIV-1 proteins. In an attempt to increase the immunogenicity of HIV-1 Gag, we created Gag variants that were targeted to the proteasomal pathway for rapid degradation. This enhanced rate of degradation was associated with increased presentation of MHC class I-associated antigenic peptides on the cell surface. Despite this, immunizing mice with either plasmid DNA or recombinant vaccinia vectors expressing unstable Gag failed to produce significant increases in bulk CTL responses or Ag-specific production of IFN-γ by CD8+ T cells compared with mice immunized with stable forms of Gag. Production of IFN-γ by CD4+ T cells was also impaired, and we speculate that the abrogation of CD4+ T cell help was responsible for the impaired CTL response. These results suggest that vaccine strategies designed to increase the density of peptide-MHC class I complexes on the surfaces of APC may not necessarily enhance immunogenicity with respect to CTL responses.
Functional Maturation of CD4+CD25+CTLA4+CD45RA+ T Regulatory Cells in Human Neonatal T Cell Responses to Environmental Antigens/Allergens
Authors: Thornton Catherine A. , Upham John W. , Wikström Matthew E. , Holt Barbara J. , White Gregory P. , Sharp Mary J. , Sly Peter D. , Holt Patrick G. 
Published: April 2014

AbstractA number of laboratories have reported cord blood T cell responses to ubiquitous environmental Ags, including allergens, by proliferation and cytokine secretion. Moreover, the magnitude of these responses has been linked with risk for subsequent expression of allergy. These findings have been widely interpreted as evidence for transplacental priming and the development of fetal T memory cells against Ags present in the maternal environment. However, we present findings below that suggest that neonatal T cell responses to allergens (and other Ags) differ markedly from those occurring in later life. Notably, in contrast to allergen-responsive adult CD4+ T cell cultures, responding neonatal T cell cultures display high levels of apoptosis. Comparable responses were observed against a range of microbial Ags and against a parasite Ag absent from the local environment, but not against autoantigen. A notable finding was the appearance in these cultures of CD4+CD25+CTLA4+ T cells that de novo develop MLR-suppressive activity. These cells moreover expressed CD45RA and CD38, hallmarks of recent thymic emigrants. CFSE-labeling studies indicate that the CD4+CD25+ cells observed at the end of the culture period were present in the day 0 starting populations, but they were not suppressive in MLR responses. Collectively, these findings suggest that a significant component of the reactivity of human neonatal CD4+ T cells toward nominal Ag (allergen) represents a default response by recent thymic emigrants, providing an initial burst of short-lived cellular immunity in the absence of conventional T cell memory, which is limited in intensity and duration via the parallel activation of regulatory T cells.
Size-Dependent Immunogenicity: Therapeutic and Protective Properties of Nano-Vaccines against Tumors
Authors: Fifis Theodora , Gamvrellis Anita , Crimeen-Irwin Blessing , Pietersz Geoffrey A. , Li Jie , Mottram Patricia L. , McKenzie Ian F. C. , Plebanski Magdalena 
Published: April 2014

AbstractInfection can protect against subsequent disease by induction of both humoral and cellular immunity, but inert protein-based vaccines are not as effective. In this study, we present a new vaccine design, with Ag covalently conjugated to solid core nano-beads of narrowly defined size (0.04–0.05 μm) that localize to dendritic cells (DEC205+ CD40+, CD86+) in draining lymph nodes, inducing high levels of IFN-γ production (CD8 T cells: precursor frequencies 1/5000 to 1/1000) and high Ab titers in mice. Conjugation of Ag to these nano-beads induced responses that were significantly higher (2- to 10-fold) than those elicited by other bead sizes, and higher than a range of currently used adjuvants (alum, QuilA, monophosphoryl lipid A). Responses were comparable to CFA/IFA immunization for Abs and ex vivo peptide-pulsed dendritic cell immunization for CD8 T cells. A single dose of Ag-conjugated beads protected mice from tumors in two different model challenges and caused rapid clearance of established tumors in mice. Thus, a range of Ags conjugated to nano-beads was effective as immunogens in both therapeutic and prophylactic scenarios.
Ceramide Inhibits IL-2 Production by Preventing Protein Kinase C-Dependent NF-κB Activation: Possible Role in Protein Kinase Cθ Regulation
Authors: Abboushi Nour , El-Hed Aimee , El-Assaad Wissal , Kozhaya Lina , El-Sabban Marwan E. , Bazarbachi Ali , Badreddine Rami , Bielawska Alicja , Usta Julnar , Dbaibo Ghassan S. 
Published: April 2014

AbstractThe role of the sphingolipid ceramide in modulating the immune response has been controversial, in part because of conflicting data regarding its ability to regulate the transcription factor NF-κB. To help clarify this role, we investigated the effects of ceramide on IL-2, a central NF-κB target. We found that ceramide inhibited protein kinase C (PKC)-mediated activation of NF-κB. Ceramide was found to significantly reduce the kinase activity of PKCθ as well as PKCα, the critical PKC isozymes involved in TCR-induced NF-κB activation. This was followed by strong inhibition of IL-2 production in both Jurkat T leukemia and primary T cells. Exogenous sphingomyelinase, which generates ceramide at the cell membrane, also inhibited IL-2 production. As expected, the repression of NF-κB activation by ceramide led to the reduction of transcription of the IL-2 gene in a dose-dependent manner. Inhibition of IL-2 production by ceramide was partially overcome when NF-κB nuclear translocation was reconstituted with activation of a PKC-independent pathway by TNF-α or when PKCθ was overexpressed. Importantly, neither the conversion of ceramide to complex glycosphingolipids, which are known to have immunosuppressive effects, nor its hydrolysis to sphingosine, a known inhibitor of PKC, was necessary for its inhibitory activity. These results indicate that ceramide plays a negative regulatory role in the activation of NF-κB and its targets as a result of inhibition of PKC.
Naive T Cells Are Resistant to Anergy Induction by Anti-CD3 Antibodies
Authors: Andris Fabienne , Denanglaire Sébastien , de Mattia Fabrizio , Urbain Jacques , Leo Oberdan 
Published: April 2014

AbstractAnti-CD3 mAbs are potent immunosuppressive agents used in clinical transplantation. It has been generally assumed that one of the anti-CD3 mAb-mediated tolerance mechanisms is through the induction of naive T cell unresponsiveness, often referred to as anergy. We demonstrate in this study that naive T cells stimulated by anti-CD3 mAbs both in vivo and in vitro do not respond to the superantigen staphylococcal enterotoxin B nor to soluble forms of anti-CD3 mAbs and APC, but express increased reactivity to plastic-coated forms of the same anti-CD3 mAbs and to their nominal Ag/class II MHC, a finding that is difficult to rationalize with the concept of anergy. Phenotypic and detailed kinetic studies further suggest that a strong signal 1 delivered by anti-CD3 mAbs in the absence of costimulatory molecules does not lead to anergy, but rather induces naive T cells to change their mitogen responsiveness and acquire features of memory T cells. In marked contrast, Ag-experienced T cells are sensitive to anergy induction under the same experimental settings. Collectively, these studies demonstrate that exposure of naive T cells in vivo and in vitro to a strong TCR stimulus does not induce Ag unresponsiveness, indicating that sensitivity to negative signaling through TCR/CD3 triggering is developmentally regulated in CD4+ T cells.
Vav-Dependent and Vav-Independent Phosphatidylinositol 3-Kinase Activation in Murine B Cells Determined by the Nature of the Stimulus
Authors: Vigorito Elena , Bardi Giuseppe , Glassford Janet , Lam Eric W.-F. , Clayton Elizabeth , Turner Martin 
Published: April 2014

Abstract
We show in this study that B cell activation following high avidity ligation of IgM or coligation of membrane Ig with CD19 elicits similar levels of Ca2+ flux using different mechanisms. Each form of activation requires the function of Vav and PI3K. However, Vav regulates Ca2+ flux independently of PI3K following anti-IgM cross-linking. By contrast, Vav function is essential for PI3K activation following membrane Ig (mIg)/CD19 coligation. Inhibition of PI3K revealed anti-IgM-stimulated Ca2+ flux has a PI3K-independent component, while Ca2+ flux following mIg/CD19 coligation is totally PI3K dependent. The p85α and p110δ subunits of PI3K both participate in anti-IgM and mIg/CD19 coligation-induced Ca2+ flux, although the defects are not as severe as observed after pharmacological inhibition. This may reflect the recruitment of additional PI3K subunits, as we found that p110α becomes associated with CD19 upon B cell activation. These data show that the nature of the Ag encountered by B cells determines the contribution of Vav proteins to PI3K activation. Our results indicate that the strong signals delivered by multivalent cross-linking agents activate B cells in a qualitatively different manner from those triggered by coreceptor recruitment.
The Complete Map of the Ig Heavy Chain Constant Gene Region Reveals Evidence for Seven IgG Isotypes and for IgD in the Horse
Authors: Wagner Bettina , Miller Donald C. , Lear Teri L. , Antczak Douglas F. 
Published: April 2014

Abstract
This report contains the first map of the complete Ig H chain constant (IGHC) gene region of the horse (Equus caballus), represented by 34 overlapping clones from a new bacterial artificial chromosome library. The different bacterial artificial chromosome inserts containing IGHC genes were identified and arranged by hybridization using overgo probes specific for individual equine IGHC genes. The analysis of these IGHC clones identified two previously undetected IGHC genes of the horse. The newly found IGHG7 gene, which has a high homology to the equine IGHG4 gene, is located between the IGHG3 and IGHG4 genes. The high degree of conservation shared between the nucleotide sequences of the IGHG7 and IGHG4 genes is unusual for the IGHG genes of the horse and suggests that these two genes duplicated most recently during evolution of the equine IGHG genes. Second, we present the genomic nucleotide sequence of the equine IGHD gene, which is located downstream of the IGHM gene. Both the IGHG7 and IGHD genes were found to be expressed at the mRNA level. The order of the 11 IGHC genes in the IGH-locus of the horse was determined to be 5′-M-D-G1-G2-G3-G7-G4-G6-G5-E-A-3′, confirming previous studies using λ phage clones, with the exception that the IGHG5 gene was found to be the most downstream-located IGHG gene. Fluorescence in situ hybridization was used to localize the IGHC region to Equus caballus (ECA) 24qter, the horse chromosome corresponding to human chromosome 14, where the human IGH locus is found.
Targeted Deletion of Protein Kinase C λ Reveals a Distribution of Functions between the Two Atypical Protein Kinase C Isoforms
Authors: Soloff Rachel S. , Katayama Carol , Lin Meei Yun , Feramisco James R. , Hedrick Stephen M. 
Published: April 2014

Abstract
Protein kinase C λ (PKCλ) is an atypical member of the PKC family of serine/threonine kinases with high similarity to the other atypical family member, PKCζ. This similarity has made it difficult to determine specific roles for the individual atypical isoforms. Both PKCλ and PKCζ have been implicated in the signal transduction, initiated by mediators of innate immunity, that culminates in the activation of MAPKs and NF-κB. In addition, work from invertebrates shows that atypical PKC molecules play a role in embryo development and cell polarity. To determine the unique functions of PKCλ, mice deficient for PKCλ were generated by gene targeting. The ablation of PKCλ results in abnormalities early in gestation with lethality occurring by embryonic day 9. The role of PKCλ in cytokine-mediated cellular activation was studied by making mouse chimeras from PKCλ-deficient embryonic stem cells and C57BL/6 or Rag2-deficient blastocysts. Cell lines derived from these chimeric animals were then used to dissect the role of PKCλ in cytokine responses. Although the mutant cells exhibited alterations in actin stress fibers and focal adhesions, no other phenotypic differences were noted. Contrary to experiments using dominant interfering forms of PKCλ, mutant cells responded normally to TNF, serum, epidermal growth factor, IL-1, and LPS. In addition, no abnormalities were found in T cell development or T cell activation. These data establish that, in vertebrates, the two disparate functions of atypical PKC molecules have been segregated such that PKCζ mediates signal transduction of the innate immune system and PKCλ is essential for early embryogenesis.
Dissecting MHC Class II Export, B Cell Maturation, and DM Stability Defects in Invariant Chain Mutant Mice
Authors: Koonce Chad H. , Bikoff Elizabeth K. 
Published: April 2014

AbstractInvariant (Ii) chain loss causes defective class II export, B cell maturation, and reduced DM stability. In this study, we compare Ii chain and class II mutant mouse phenotypes to dissect these disturbances. The present results demonstrate that ER retention of αβ complexes, and not β-chain aggregates, disrupts B cell development. In contrast, we fail to detect class II aggregates in Ii chain mutant thymi. Ii chain loss in NOD mice leads to defective class II export and formation of αβ aggregates, but in this background, downstream signals are misregulated and mature B cells develop normally. Finally, Ii chain mutant strains all display reduced levels of DM, but mice expressing either p31 or p41 alone, and class II single chain mutants, are indistinguishable from wild type. We conclude that Ii chain contributions as a DM chaperone are independent of its role during class II export. This Ii chain/DM partnership favors class II peptide loading via conventional pathway(s).
CCR5-Deficient Mice ControlMycobacterium tuberculosisInfection despite Increased Pulmonary Lymphocytic Infiltration
Authors: Scott Algood Holly M. , Flynn JoAnne L. 
Published: April 2014

AbstractThe control of Mycobacterium tuberculosis infection is dependent on the development of an adaptive immune response, which is mediated by granulomas. The granuloma is a dynamic structure that forms in the lung and consists primarily of macrophages and lymphocytes. For this structure to be effective in containment of the bacillus, it must develop in an organized and timely manner. The formation of the granuloma is dependent on recruitment of activated cells through adhesion molecules and chemokines. M. tuberculosis infection causes an increase in the expression of β-chemokines CCL3, CCL4, and CCL5, and their receptor CCR5, in the lungs. In this study, we demonstrate that CCR5-transgenic knockout mice were capable of recruiting immune cells to the lung to form granulomas. CCR5−/− mice successfully induced a Th1 response and controlled infection. Unexpectedly, M. tuberculosis infection in these mice resulted in greater numbers of lymphocytes migrating to the lung and higher levels of many inflammatory cytokines, compared with wild-type mice, without apparent long-term detrimental effects. In the absence of CCR5, there were more dendritic cells in the lung-draining lymph nodes and more primed T lymphocytes in these mice. Bacterial numbers in the lymph nodes were also higher in CCR5−/− mice. Therefore, CCR5 may play a role in the migration of dendritic cells to and from the lymph nodes during M. tuberculosis infection.
Inhibition of Lipopolysaccharide-Induced Macrophage IL-12 Production byLeishmania mexicanaAmastigotes: The Role of Cysteine Peptidases and the NF-κB Signaling Pathway
Authors: Cameron Pamela , McGachy Adrienne , Anderson Mary , Paul Andrew , Coombs Graham H. , Mottram Jeremy C. , Alexander James , Plevin Robin 
Published: April 2014

AbstractInfection with lesion-derived Leishmania mexicana amastigotes inhibited LPS-induced IL-12 production by mouse bone marrow-derived macrophages. This effect was associated with expression of cysteine peptidase B (CPB) because amastigotes of CPB deletion mutants had limited ability to inhibit IL-12 production, whereas preincubation of cells with a CPB inhibitor, cathepsin inhibitor IV, was able to suppress the effect of wild-type amastigotes. Infection with wild-type amastigotes resulted in a time-dependent proteolytic degradation of IκBα and IκBβ and the related protein NF-κB. This effect did not occur with amastigotes of CPB deletion mutants or wild-type promastigotes, which do not express detectable CPB. NF-κB DNA binding was also inhibited by amastigote infection, although nuclear translocation of cleaved fragments of p65 NF-κB was still observed. Cysteine peptidase inhibitors prevented IκBα, IκBβ, and NF-κB degradation induced by amastigotes, and recombinant CPB2.8, an amastigote-specific isoenzyme of CPB, was shown to degrade GST-IκBα in vitro. LPS-mediated IκBα and IκBβ degradation was not affected by these inhibitors, confirming that the site of degradation of IκBα, IκBβ, and NF-κB by the amastigotes was not receptor-driven, proteosomal-mediated cleavage. Infection of bone marrow macrophages with amastigotes resulted in cleavage of JNK and ERK, but not p38 MAPK, whereas preincubation with a cysteine peptidase inhibitor prevented degradation of these proteins, but did not result in enhanced protein kinase activation. Collectively, our results suggest that the amastigote-specific cysteine peptidases of L. mexicana are central to the ability of the parasite to modulate signaling via NF-κB and consequently inhibit IL-12 production.
TGF-β Receptor Signaling Is Critical for Mucosal IgA Responses
Authors: Borsutzky Stefan , Cazac Balthazar B. , Roes Jürgen , Guzmán Carlos A. 
Published: April 2014

AbstractTGF-β receptor (TβR) signaling is important for systemic IgA production; however, its contribution to IgA secretion at mucosal sites remained uncertain. This important question was addressed using mice lacking the TβR in B cells (TβRII-B). Although reduced, IgA-secreting cells and IgA were still present in the systemic and mucosal compartments. The adaptive immune response was investigated after oral or nasal immunization using adjuvants acting on different molecular targets, namely, the cholera toxin B subunit and the macrophage-activating lipopeptide-2. Efficient Ag-specific cellular and humoral responses were triggered both in controls and TβRII-B mice. However, a significant reduction in Ag-specific IgG2b and increased levels of IgG3 were observed in sera from TβRII-B mice. Furthermore, Ag-specific IgA-secreting cells, serum IgA, and secretory IgA were undetectable in TβRII-B mice. These results demonstrate the critical role played by TβR in Ag-driven stimulation of secretory IgA responses in vivo.
The Cholera Toxin-Derived CTA1-DD Vaccine Adjuvant Administered Intranasally Does Not Cause Inflammation or Accumulate in the Nervous Tissues
Authors: Eriksson Anna M. , Schön Karin M. , Lycke Nils Y. 
Published: April 2014

AbstractAlthough highly effective, the use of GM1-receptor binding holotoxins as nasal mucosal adjuvants has recently been cautioned due to the risk for their accumulation in the brain and other nervous tissues. Therefore we have explored the efficacy of the CTA1-DD adjuvant for its ability to enhance nasal immune responses in mice. We found that despite the lack of a mucosal binding element, the B cell-targeted CTA1-DD molecule was an equally strong adjuvant as cholera toxin (CT). The potency of CTA1-DD was not a result of endotoxin contamination because more than a 50-fold higher dose of LPS was needed to achieve a similar enhancement. Moreover, the adjuvant effect was TLR4-independent and absent in mutant CTA1-E112K-DD, lacking enzymatic activity. The CTA1-DD adjuvant augmented germinal center formations and T cell priming in the draining lymph nodes, and contrary to CT, promoted a balanced Th1/Th2 response with little effect on IgE Ab production. CTA1-DD did not induce inflammatory changes in the nasal mucosa, and most importantly did not bind to or accumulate in the nervous tissues of the olfactory bulb, whereas CT bound avidly to the nervous tissues. We believe that the nontoxic CTA1-DD adjuvant is an attractive solution to the current dilemma between efficacy and toxicity encountered in CT-holotoxin adjuvant or Escherichia coli heat-labile toxin-holotoxin adjuvant strategies and provides a safe and promising candidate to be included in future vaccines for intranasal administration.