bluuebunny/crossref_metadata_2025_split huggingface dataset:
Antagonism of Direct Alloreactivity of an HLA-B27-Specific CTL Clone by Altered Peptide Ligands of Its Natural Epitope
Authors: García-Peydró Marina , Paradela Alberto , Albar Juan P. , Castro José A. López de 
Published: April 2014

AbstractAntagonism of allospecific CTL by altered MHC ligands is a potential approach to specific immunomodulation of allogeneic T cell responses in acute graft rejection and graft-vs-host disease. In this study we have analyzed the capacity of peptide analogs of a natural HLA-B27-allospecific CTL epitope to antagonize direct alloreactivity. Alanine scanning demonstrated that positions 4, 5, and 7 of the peptide epitope were critical for allorecognition. A number of relatively conservative substitutions at each of these positions were then tested for their effect on allorecognition and antagonism. All substitutions at position 5 abrogated cytotoxicity. In contrast, a few changes at positions 4 and 7 were tolerated, indicating a limited flexibility of the allospecific CTL in recognition of peptide epitope variants. Most of the substitutions impairing cytotoxicity actually induced antagonism. However, whereas epitope variants with changes at positions 4 and 7 behaved as weak or intermediate antagonists, some of the variants with changes at position 5 antagonized CTL alloreactivity almost completely. The results in this study demonstrate for the first time that antagonism of direct class I-mediated alloreactivity can be achieved by variants of a natural allospecific peptide epitope.
Antibodies Directed Against the MHC-I Molecule H-2Dd Complexed with an Antigenic Peptide: Similarities to a T Cell Receptor with the Same Specificity
Authors: Polakova Katarina , Plaksin Daniel , Chung Doo Hyun , Belyakov Igor M. , Berzofsky Jay A. , Margulies David H. 
Published: April 2014

Abstractαβ TCRs, which use an Ab-like structure to form a combining site, recognize molecular complexes consisting of peptides bound to MHC class I (MHC-I) or class II (MHC-II) molecules. To explore the similarities and differences between Ab and T cell recognition of similar structures, we have isolated two mAbs, KP14 and KP15, that specifically bind H-2Dd complexed with an HIV envelope gp160-derived peptide, P18-I10. These Abs are MHC and peptide specific. Fine specificity of mAb binding was analyzed using a panel of synthetic peptides, revealing similarities between the mAb and a cloned TCR with the same specificity. These two mAbs used the same VH and JH gene segments, but different D, Vκ, and Jκ genes. Administered in vivo, mAb KP15 blocked the induction of CTL specific for recombinant vaccinia virus-encoded gp160, indicating its ability to bind endogenously generated MHC/peptide complexes. Analysis of the fine specificity of these mAbs in the context of their encoded amino acid sequences and the known three-dimensional structure of the H-2Dd/P18-I10 complex suggests that they bind in an orientation similar to that of the TCR. Thus, the plasticity of the B cell receptor repertoire and the structural similarities among BCR and TCR allow Abs to effectively mimic αβ TCRs. Such mAbs may be useful in the therapeutic modulation of immune responses against infectious agents or harmful self Ags as well as in tracing steps in Ag processing.
CTL-Mediated Killing of IntracellularMycobacterium tuberculosisIs Independent of Target Cell Nuclear Apoptosis
Authors: Thoma-Uszynski Sybille , Stenger Steffen , Modlin Robert L. 
Published: April 2014

AbstractTwo subsets of human CTL have been defined based upon phenotype and function: CD4− CD8− double-negative (DN) CTL lyse susceptible targets via Fas-Fas ligand interaction and CD8+ CTL via the granule exocytosis pathway. CD8+ CTL, but not DN CTL, can mediate an antimicrobial activity against Mycobacterium tuberculosis-infected target cells that is dependent on cytotoxic granules that contain granulysin. We investigated the role of nuclear apoptosis for the antimicrobial effector function of CD1-restricted CTL using the caspase inhibitor N-benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone. We found that DN CTL-induced target cell lysis was completely dependent on caspase activation, whereas the cytolytic activity of CD8+ CTL was caspase independent. However, both DN and CD8+ CTL-induced nuclear apoptosis required caspase activation. More important, the antimicrobial effector function of CD8+ CTL was not diminished by inhibition of caspase activity. These data indicate that target cell nuclear apoptosis is not a requirement for CTL-mediated killing of intracellular M. tuberculosis.
Specific Deficiency of p56lck Expression in T Lymphocytes from Type 1 Diabetic Patients
Authors: Nervi Solange , Atlan-Gepner Catherine , Kahn-Perles Brigitte , Lecine Patrick , Vialettes Bernard , Imbert Jean , Naquet Philippe 
Published: April 2014

Abstract
Peripheral T lymphocyte activation in response to TCR/CD3 stimulation is reduced in type 1 diabetic patients. To explore the basis of this deficiency, a comprehensive analysis of the signal transduction pathway downstream of the TCR/CD3 complex was performed for a cohort of patients (n = 38). The main result of the study shows that T cell hyporesponsiveness is positively correlated with a reduced amount of p56lck in resting T lymphocytes. Upon CD3-mediated activation, this defect leads to a hypophosphorylation of the CD3ζ-chain and few other polypeptides without affecting the recruitment of ZAP70. Other downstream effectors of the TCR/CD3 transduction machinery, such as phosphatidylinositol 3-kinase p85α, p59fyn, linker for activation of T cells (LAT), and phospholipase C-γ1, are not affected. In some patients, the severity of this phenotypic deficit could be linked to low levels of p56lck mRNA and resulted in the failure to efficiently induce the expression of the CD69 early activation marker. We propose that a primary deficiency in human type 1 diabetes is a defect in TCR/CD3-mediated T cell activation due to the abnormal expression of the p56lck tyrosine kinase.
Contribution of CD95 Ligand-Induced Neutrophil Infiltration to the Bystander Effect in p53 Gene Therapy for Human Cancer
Authors: Waku Toshihiko , Fujiwara Toshiyoshi , Shao Jianghua , Itoshima Takahiro , Murakami Takayoshi , Kataoka Masafumi , Gomi Shinya , Roth Jack A. , Tanaka Noriaki 
Published: April 2014

AbstractClinical trials of adenoviral p53 gene therapy provide the evidence that the bystander effect induced by the wild-type p53 gene transfer on adjacent tumor cells contributes to tumor progression; its mechanism, however, remains uncharacterized. We report in this work that injection of adenovirus expressing the human wild-type p53 gene (Ad5CMVp53) into established human colorectal tumors in nu/nu mice resulted in CD95 ligand (CD95L) overexpression, followed by a massive neutrophil infiltration. Culture supernatants of human colorectal cancer cells infected with Ad5CMVp53 exhibited a potent chemotactic activity against murine polymorphonuclear neutrophils, which could be abolished by the anti-CD95L mAb (NOK-1). In vivo cell depletion experiments indicated that neutrophils were in part responsible for the antitumor effect of the Ad5CMVp53 infection. Our data directly suggest that overexpression of CD95L by the wild-type p53 gene transfer induces neutrophil infiltration into human colorectal tumors, which may play a critical role in the bystander effect of p53 gene therapy.
Neonatal Dexamethasone Treatment Increases Susceptibility to Experimental Autoimmune Disease in Adult Rats
Authors: Bakker Joost M. , Kavelaars Annemieke , Kamphuis Patrick J. G. H. , Cobelens Pieter M. , van Vugt Harmke H. , van Bel Frank , Heijnen Cobi J. 
Published: April 2014

AbstractMajor concern has emerged about the possible long term adverse effects of glucocorticoid treatment, which is frequently used for the prevention of chronic lung disease in preterm infants. Here we show that neonatal glucocorticoid treatment of rats increases the severity (p ≤ 0.01) and incidence (p ≤ 0.01) of the inflammatory autoimmune disease experimental autoimmune encephalomyelitis in adult life. In search of possible mechanisms responsible for the increased susceptibility to experimental autoimmune encephalomyelitis, we investigated the reactivity of the hypothalamo-pituitary-adrenal axis and of immune cells in adult rats after neonatal glucocorticoid treatment. We observed that neonatal glucocorticoid treatment reduces the corticosterone response after an LPS challenge in adult rats (p ≤ 0.001). Interestingly, LPS-stimulated macrophages of glucocorticoid-treated rats produce less TNF-α and IL-1β in adult life than control rats (p &lt; 0.05). In addition, splenocytes obtained from adult rats express increased mRNA levels of the proinflammatory cytokines IFN-γ (p &lt; 0.01) and TNF-β (p &lt; 0.05) after neonatal glucocorticoid treatment. Apparently, neonatal glucocorticoid treatment has permanent programming effects on endocrine as well as immune functioning in adult life. In view of the frequent clinical application of glucocorticoids to preterm infants, our data demonstrate that neonatal glucocorticoid treatment may be a risk factor for the development of (auto)immune disease in man.
Antigen-Specific T Cells Transduced with IL-10 Ameliorate Experimentally Induced Arthritis Without Impairing the Systemic Immune Response to the Antigen
Authors: Setoguchi Keigo , Misaki Yoshikata , Araki Yasuto , Fujio Keishi , Kawahata Kimito , Kitamura Toshio , Yamamoto Kazuhiko 
Published: April 2014

AbstractFor the treatment of rheumatoid arthritis, efficient drug delivery methods to the inflamed joints need to be developed. Because T cells expressing an appropriate autoantigen-specific receptor can migrate to inflamed lesions, it has been reasoned that they can be employed to deliver therapeutic agents. To examine the ability and efficiency of such T cells as a vehicle, we employed an experimentally induced model of arthritis. Splenic T cells from DO11.10 TCR transgenic mice specific for OVA were transduced with murine IL-10. Adoptive transfer of the IL-10-transduced DO11.10 splenocytes ameliorated OVA-induced arthritis despite the presence of around 95% nontransduced cells. Using green fluorescent protein as a marker for selection, the number of transferred cells needed to ameliorate the disease was able to be reduced to 104. Preferential accumulation of the transferred T cells was observed in the inflamed joint, and the improvement in the disease was not accompanied by impairment of the systemic immune response to the Ag, suggesting that the transferred T cells exert their anti-inflammatory task locally, mainly in the joints where the Ag exists. In addition, IL-10-transduced DO11.10 T cells ameliorated methylated BSA-induced arthritis when the arthritic joint was coinjected with OVA in addition to methylated BSA. These results suggest that T cells specific for a joint-specific Ag would be useful as a therapeutic vehicle in rheumatoid arthritis for which the arthritic autoantigen is still unknown.
Cutting Edge: STAT6-Deficient Mice Have Enhanced Tumor Immunity to Primary and Metastatic Mammary Carcinoma
Authors: Ostrand-Rosenberg Suzanne , Grusby Michael J. , Clements Virginia K. 
Published: April 2014

AbstractSTAT4 and STAT6 are essential for the development of CD4+ Th1 and Th2 development, respectively. Tumor immunologists have hypothesized that Th1 cells are critical in tumor immunity because they facilitate differentiation of CD8+ T cells, which are potent anti-tumor effectors. We have used STAT4−/− and STAT6−/− mice to test this hypothesis. BALB/c and knockout mice were challenged in the mammary gland with the highly malignant and spontaneously metastatic BALB/c-derived 4T1 mammary carcinoma. Primary tumor growth and metastatic disease are reduced in STAT6−/− mice relative to BALB/c and STAT4−/− mice. Ab depletions demonstrate that the effect is mediated by CD8+ T cells, and immunized STAT6−/− mice have higher levels of 4T1-specific CTL than BALB/c or STAT4−/− mice. Surprisingly, Th1 or Th2 cells are not involved, because CD4 depletion does not diminish the anti-tumor effect. Therefore, deletion of the STAT6 gene facilitates development of potent anti-tumor immunity via a CD4+-independent pathway.
Spontaneous Rejection of Poorly Immunogenic P1.HTR Tumors by Stat6-Deficient Mice
Authors: Kacha Aalok K. , Fallarino Francesca , Markiewicz Mary A. , Gajewski Thomas F. 
Published: April 2014

AbstractExperimental evidence suggests that a type 1 T cell response may result in optimal tumor rejection in vivo. This phenotype is determined in part by cytokines that influence T cell differentiation. In transplantable tumor models such as P1.HTR, tumors grow progressively despite expression of defined tumor Ags. We hypothesized that this failure to reject may be due to poor generation of a type 1 phenotype, through a dominant influence of the type 2-promoting cytokines IL-4 and/or IL-13. This hypothesis was tested by implanting P1.HTR tumors into mice deficient in Stat6. In contrast to progressive growth of P1.HTR tumors in wild-type mice, and aggressive growth even of IL-12-transfected P1.HTR in Stat1−/− mice, P1.HTR was spontaneously rejected by Stat6−/− mice. Rejection was accompanied by augmented tumor-specific IFN-γ production and CTL activity. These results suggest that pharmacologic inhibition of Stat6 signaling could potentiate anti-tumor immunity in vivo.
Altered Selection of CD4+ T Cells by Class II MHC Bound with Dominant and Low Abundance Self-Peptides
Authors: Gaszewska-Mastalarz Anna , Muranski Pawel , Chmielowski Bartosz , Kraj Piotr , Ignatowicz Leszek 
Published: April 2014

Abstract
We have investigated the development of CD4+ T cells in mice expressing low levels of transgenic class II MHC molecules (Ab) preoccupied with covalent peptide (Ep), which in the presence of invariant chain (Ii) is extensively cleaved and replaced with self-derived peptides. In these mice, the transgenic Ab molecules, bound with predominant peptide (Ep) and with multiple self-peptides, selected more CD4+ T cells than Ab/self-peptide complexes expressed in wild-type mice. The enhanced outcome of thymic selection was a result of impaired negative selection, rather than more efficient positive selection by an overall lowered abundance of self-derived Ab/peptide complexes. Peripheral CD4+ T cells in the AbEpIi+ mice had memory phenotype, often followed by polyclonal activation of B cells. The AbEpIi+ mice preserved their good health and had a normal life span despite the profound number of activated CD4+ T cells and B cells in peripheral lymphoid organs, moderate hypergammaglobulinemia, and deposited complexes in the kidneys. We propose that CD4+ T cells positively selected due to low avidity for high abundant AbEp complex avoid negative selection on Ab molecules loaded with low abundant peptides and become self-reactive in the peripheral lymphoid organs.
Absence of Functional Inducible NO Synthase Enhances the Efficacy of Tolerance Induced by High Dose Antigen Feeding
Authors: Kahn Daniel A. , Archer D. Clay , Kelly Carolyn J. 
Published: April 2014

AbstractRecent studies have suggested that IL-12 and IFN-γ may impair the ability of fed Ag to induce systemic tolerance. Because both of these cytokines can function to directly or indirectly induce inducible NO synthase (iNOS) expression, we have investigated whether the functional expression of iNOS regulates oral tolerance. C57BL/6J wild-type or C57BL/6J NOS2−/− mice were gavaged with a single dose of 20 mg of keyhole limpet hemocyanin (KLH), followed by s.c. immunization with KLH/CFA. In the absence of feeding Ag, several parameters of the immune response were more robust in C57BL/6J NOS2−/− mice following KLH/CFA immunization, including the magnitude of the delayed-type hypersensitivity response, the proliferative response, and the production of IFN-γ and IL-2 by Ag-activated draining lymph node cells. These heightened responses in the C57BL/6J NOS2−/− mice are still effectively inhibited by feeding KLH. Feeding KLH to the C57BL/6J NOS2−/− mice elicited heightened TGF-β1 production by Ag-activated lymphocytes, as well as augmented total IgG, IgG1, and IgG2a responses to KLH/CFA compared with that seen in Ag-fed wild-type mice. Feeding Ag to the NOS2−/− mice suppressed proliferative responses and IFN-γ production, while increasing IL-4 production and the IgG1/IgG2a ratio even following a booster immunization of KLH/CFA. Administrating l-N6-(1-iminoethyl)-lysine · 2HCl to wild-type mice during the period of Ag feeding reproduced the high TGF-β1 production seen in Ag-activated lymphocytes from Ag-fed NOS2−/− mice. Feeding KLH is followed by transient up-regulation of NOS2 mRNA expression in the Peyer’s patches of wild-type mice. Selective inhibition of NOS2 may be a simple way to augment tolerogenic mucosal immune responses.
In Vivo Cross-Presentation of a Soluble Protein Antigen: Kinetics, Distribution, and Generation of Effector CTL Recognizing Dominant and Subdominant Epitopes
Authors: Nelson Delia , Bundell Christine , Robinson Bruce 
Published: April 2014

AbstractCross-presentation of exogenous Ags via the MHC class I pathway is now recognized for its role in self-tolerance, tumor immunity, and vaccine development. However, little is known about the in vivo distribution and kinetics of cross-presented protein Ags, nor the subsequent development of CTL effector responses to dominant or subdominant epitopes. We examined the location and duration of cross-presented Ag by using 5,6-carboxy-succinimidyl-fluorescein ester-labeled T cells from class I-restricted Ag-specific TCR mice. Comparisons of results from an in vitro 51Cr release CTL assay with an in vivo CTL assay provided physiologically relevant insights into the functional capacities of CTL specific for epitopes with differing affinities. These data demonstrate that efficient cross-presentation of a dominant class I-restricted Ag is dose related and remains largely localized, but not limited to the draining lymph nodes for up to 3 wk following a single injection of soluble protein. Within this period, dominant peptide-specific CTL are fully functional in vivo throughout the secondary lymphoid system. However, no in vivo responses are seen to a subdominant or cryptic epitope. Prolonging Ag cross-presentation via use of IFA promoted persisting in vivo dominant epitope-specific CTL activity and revealed dose-responsive precursor CTL to the subdominant, but not to a cryptic epitope. Analysis of functional in vivo CTL responses demonstrated that, in the presence of strong ongoing responses to the dominant peptide, lytic activity of CTL directed at weaker epitopes is undetectable.
Vaccination with Empty Plasmid DNA or CpG Oligonucleotide Inhibits Diabetes in Nonobese Diabetic Mice: Modulation of Spontaneous 60-kDa Heat Shock Protein Autoimmunity
Authors: Quintana Francisco J. , Rotem Asaf , Carmi Pnina , Cohen Irun R. 
Published: April 2014

Abstract
Nonobese diabetic (NOD) mice develop insulitis and diabetes through a process involving autoimmunity to the 60-kDa heat shock protein (HSP60). Treatment of NOD mice with HSP60 or with peptides derived from HSP60 inhibits this diabetogenic process. We now report that NOD diabetes can be inhibited by vaccination with a DNA construct encoding human HSP60, with the pcDNA3 empty vector, or with an oligonucleotide containing the CpG motif. Prevention of diabetes was associated with a decrease in the degree of insulitis and with down-regulation of spontaneous proliferative T cell responses to HSP60 and its peptide p277. Moreover, both the pcDNA3 vector and the CpG oligonucleotide induced specific Abs, primarily of the IgG2b isotype, to HSP60 and p277, and not to other islet Ags (glutamic acid decarboxylase or insulin) or to an unrelated recombinant Ag expressed in bacteria (GST). The IgG2b isotype of the specific Abs together with the decrease in T cell proliferative responses indicate a shift of the autoimmune process to a Th2 type in treated mice. These results suggest that immunostimulation by bacterial DNA motifs can modulate spontaneous HSP60 autoimmunity and inhibit NOD diabetes.
IL-4-Activated STAT-6 Inhibits IFN-γ-Induced CD40 Gene Expression in Macrophages/Microglia
Authors: Nguyen Vince T. , Benveniste Etty N. 
Published: April 2014

AbstractThe antagonism between the cytokines IFN-γ and IL-4 is well documented, but the mechanism by which IL-4 inhibits IFN-γ-induced gene expression is not clearly understood. CD40 is a type I transmembrane protein that is critical for proper functioning of the immune system. We have previously shown that IFN-γ is the most potent inducer of CD40 expression by macrophages and microglia. In this report, we describe the molecular mechanisms by which IL-4 inhibits IFN-γ-induced CD40 expression. IL-4 suppresses IFN-γ-induced CD40 gene expression in both macrophages and microglia, and such inhibition is dependent on the activation of STAT-6. Nuclear run-on and transfection studies indicate that IL-4-mediated repression is at the transcriptional level. Furthermore, IL-4 inhibition of IFN-γ-induced CD40 expression is specific, since IL-4 does not inhibit IFN-γ-induced IFN-responsive factor-1 gene expression. Site-directed mutagenesis studies demonstrate that two STAT binding sites, named proximal and distal IFN-γ-activated sequences, in the human CD40 promoter are important for IL-4 inhibition of IFN-γ-induced CD40 promoter activity. Moreover, EMSAs indicate that IL-4-activated STAT-6 binds to these two STAT binding sites. These results suggest that IL-4 inhibition of IFN-γ-induced CD40 gene expression is mediated by direct STAT-6 binding to the CD40 promoter.
Enhanced Expression of Fas-Associated Death Domain-Like IL-1-Converting Enzyme (FLICE)-Inhibitory Protein Induces Resistance to Fas-Mediated Apoptosis in Activated Mast Cells
Authors: Yoshikawa Hideshi , Nakajima Yasuo , Tasaka Kachio 
Published: April 2014

AbstractMast cells play a critical role in host immune responses and are implicated in the pathogenesis of allergic inflammation. Though mouse mast cell line MC/9 expresses cell surface Fas Ag and is sensitive to Fas-induced apoptosis, activated MC/9 cells are resistant to Fas-induced cell death by cross-linking of FcεRI or FcγR. Fas-associated death domain-like IL-1-converting enzyme (FLICE)-inhibitory protein (FLIP), a caspase-8 inhibitor that lacks the cisteine domain, is one of the negative regulators of receptor-mediated apoptosis. In this report, we show that activation of mast cells by cross-linking of FcεRI or FcγR can induce enhanced expression of FLIP and consequently a resistance to Fas-induced apoptosis, although the expression level of Fas Ag is not changed. Addition of antisense oligonucleotide for FLIP prevents resistance to Fas-induced apoptosis of activated mast cells, suggesting that endogenous FLIP inhibits Fas-mediated apoptosis in activated mast cells. Thus, the enhanced expression of FLIP in activated mast cells contributes to the resistance to Fas-induced apoptosis, which may result in the development and prolongation of allergic inflammation.