bluuebunny/crossref_metadata_2025_split huggingface dataset:
CD25+ Immunoregulatory CD4 T Cells Mediate Acquired Central Transplantation Tolerance
Authors: Trani Jose , Moore Daniel J. , Jarrett Beth P. , Markmann Joseph W. , Lee Major K. , Singer Andrew , Lian Moh-Moh , Tran Brian , Caton Andrew J. , Markmann James F. 
Published: April 2014

Abstract
Transplantation tolerance is induced reliably in experimental animals following intrathymic inoculation with the relevant donor strain Ags; however, the immunological mechanisms responsible for the induction and maintenance of the tolerant state remain unknown. We investigated these mechanisms using TCR transgenic mice (TS1) that carry T cells specific for an immunodominant, MHC class II-restricted peptide (S1) of the influenza PR8 hemagglutinin (HA) molecule. We demonstrated that TS1 mice reject skin grafts that have transgene-encoded HA molecules (HA104) as their sole antigenic disparity and that intrathymic but not i.v. inoculation of TS1 mice with S1 peptide induces tolerance to HA-expressing skin grafts. Intrathymic peptide inoculation was associated with a dose-dependent reduction in T cells bearing high levels of TCR specific for HA. However, this reduction was both incomplete and transient, with a full recovery of S1-specific thymocytes by 4 wk. Peptide inoculation into the thymus also resulted in the generation of immunoregulatory T cells (CD4+CD25+) that migrated to the peripheral lymphoid organs. Adoptive transfer experiments using FACS sorted CD4+CD25− and CD4+CD25+ T cells from tolerant mice revealed that the former but not the latter maintain the capacity to induce rejection of HA bearing skin allografts in syngeneic hosts. Our results suggest that both clonal frequency reduction in the thymus and immunoregulatory T cells exported from the thymus are critical to transplantation tolerance induced by intrathymic Ag inoculation.
Coexpression of CD58 or CD48 with Intercellular Adhesion Molecule 1 on Target Cells Enhances Adhesion of Resting NK Cells
Authors: Barber Domingo F. , Long Eric O. 
Published: April 2014

AbstractThe β2 integrin LFA-1 (CD11a/CD18) mediates adhesion of lymphocytes to cells expressing ICAM. The strength of this adhesion is regulated by different signals delivered by cytokines and chemokines, and by the TCR in the case of T cells. To determine the receptor-ligand interactions required for adhesion of resting NK cells, Drosophila cells expressing different combinations of ligands of human NK cell receptors were generated. Expression of ICAM-1 alone was sufficient for an adhesion of resting NK cells that was sensitive to inhibitors of src family kinase and of phosphatidylinositol 3-kinase. Binding of resting NK cells to solid-phase ICAM-1 showed similar signaling requirements. A pulse of either IL-2 or IL-15 to resting NK cells resulted in strongly enhanced, actin-dependent adhesion to insect cells expressing ICAM-1 alone. Coexpression of either LFA-3 (CD58) or CD48 with ICAM-1 resulted in strong adhesion by resting NK cells, even in the absence of cytokines. Therefore, receptors for LFA-3 and CD48 on resting NK cells strengthen the adhesion mediated by LFA-1.
High Affinity Xenoreactive TCR:MHC Interaction Recruits CD8 in Absence of Binding to MHC
Authors: Buslepp Jennifer , Kerry Samantha E. , Loftus Doug , Frelinger Jeffrey A. , Appella Ettore , Collins Edward J. 
Published: April 2014

Abstract
The TCR from a xenoreactive murine cytotoxic T lymphocyte clone, AHIII 12.2, recognizes murine H-2Db complexed with peptide p1058 (FAPGFFPYL) as well as human HLA-A2.1 complexed with human self-peptide p1049 (ALWGFFPVL). To understand more about T cell biology and cross-reactivity, the ectodomains of the AHIII 12.2 TCR have been produced in E. coli as inclusion bodies and the protein folded to its native conformation. Flow cytometric and surface plasmon resonance analyses indicate that human p1049/A2 has a significantly greater affinity for the murine AHIII 12.2 TCR than does murine p1058/Db. Yet, T cell binding and cytolytic activity are independent of CD8 when stimulated with human p1049/A2 as demonstrated with anti-CD8 Abs that block CD8 association with MHC. Even in the absence of direct CD8 binding, stimulation of AHIII 12.2 T cells with “CD8-independent” p1049/A2 produces p56lck activation and calcium flux. Confocal fluorescence microscopy and fluorescence resonance energy transfer flow cytometry demonstrate CD8 is recruited to the site of TCR:peptide MHC binding. Taken together, these results indicate that there exists another mechanism for recruitment of CD8 during high affinity TCR:peptide MHC engagement.
CD28/B7 Regulation of Anti-CD3-Mediated Immunosuppression In Vivo
Authors: Tang Qizhi , Smith Judy A. , Szot Greg L. , Zhou Ping , Alegre Maria-Luisa , Henriksen Kammi J. , Thompson Craig B. , Bluestone Jeffrey A. 
Published: April 2014

Abstract
FcR-binding “classical” anti-CD3 mAb is a potent immunosuppressive drug that alters CD4+ and CD8+ T cell function in vivo via anergy induction and programmed cell death (PCD). Anti-CD3-mediated PCD was Fas independent but was mediated by the mitochondria-initiated apoptosis that was abrogated in Bcl-xL-transgenic T cells. The PCD was more pronounced in CD28-deficient mice consistent with defective Bcl-xL up-regulation. Residual T cells isolated from anti-CD3-treated wild-type, CD28−/−, and Bcl-xL-transgenic mice were hyporesponsive. The hyporesponsiveness was more pronounced in CD28−/− and wild-type mice treated with anti-B7-2, suggesting that CD28 interaction with B7-2 regulates T cell responsiveness in anti-CD3-treated animals. Finally, anti-CD3 treatment led to indefinite cardiac allograft survival in wild-type but not Bcl-xL animals. Together these results implicate CD28/B7 signaling in the regulation of both anti-CD3-induced T cell depletion and hyporesponsiveness in vivo, but T cell depletion, not hyporesponsiveness, appears to be critical for anti-CD3 mAb-mediated long-term immune regulation.
Induction of Apoptosis by HIV-1-Infected Monocytic Cells
Authors: Sperber Kirk , Beuria Prarthana , Singha Netai , Gelman Irwin , Cortes Patricia , Chen Houchu , Kraus Thomas 
Published: April 2014

Abstract
We have previously described a soluble 6000-Da peptide produced by an HIV-1-infected human macrophage cell line, clone 43HIV, which induces apoptosis in T and B cells. We have identified this factor as the novel cDNA clone FL14676485 that encodes for the human hypothetical protein, FLJ21908. The FL14676485 cDNA clone was isolated from a 43HIV λ ZAP Escherichia coli expression library and screened with a panel of rabbit and mouse anti-apoptotic Abs. We transfected the FL14676485 clone into Bosc cells and non-HIV-1-infected 43 cells. Western blot analysis of lysates from the FL14676485-transfected 43 cells and Bosc cells using anti-proapoptotic factor Abs revealed a protein with a molecular mass of 66 kDa corresponding to the size of the full-length gene product of the FL14676485 clone, while Western blot of the supernatant demonstrated a doublet of 46-kDa and 6000-Da peptide that corresponds to our previously described proapoptotic factor. Primary HIV-1BaL-infected monocytes also produce the FLJ21908 protein. Supernatants from these transfected cells induced apoptosis in PBMC, CD4+, and CD8+ T and B cells similar to the activity of our previously described proapoptotic factor. PCR analysis of 43 cells and 43HIV cells revealed a base pair fragment of 420 bp corresponding to the FL14676485 gene product in 43HIV cells, but not in 43 cells. The FLJ21908 protein induces apoptosis through activation of caspase-9 and caspase-3. We have further demonstrated that the FLJ21908 protein has apoptotic activity in the SH-SY5Y neuronal cell line and can be detected in brain and lymph tissue from HIV-1-infected patients who have AIDS dementia. The FLJ21908 protein may contribute to the apoptosis and dementia observed in AIDS patients.
Transcutaneous Immunization with Cholera Toxin B Subunit Adjuvant Suppresses IgE Antibody Responses Via Selective Induction of Th1 Immune Responses
Authors: Anjuère Fabienne , George-Chandy Annie , Audant Florence , Rousseau Déborah , Holmgren Jan , Czerkinsky Cecil 
Published: April 2014

Abstract
Topical application of cholera toxin (CT) onto mouse skin can induce a humoral immune response to CT as well as to coadministered Ags. In this study, we examined the nontoxic cell-binding B subunit of CT (CTB) as a potential adjuvant for cutaneous immune responses when coadministered with the prototype protein Ag, OVA. CTB applied onto skin induced serum Ab responses to itself with magnitudes comparable to those evoked by CT but was poorly efficient at promoting systemic Ab responses to coadministered OVA. However, transcutaneous immunization (TCI) with either CT or CTB and OVA led to vigorous OVA-specific T cell proliferative responses. Furthermore, CTB potentiated Th1-driven responses (IFN-γ production) whereas CT induced both Th1 and Th2 cytokine production. Coadministration of the toxic subunit CTA, together with CTB and OVA Ag, led to enhanced Th1 and Th2 responses. Moreover, whereas TCI with CT enhanced serum IgE responses to coadministered OVA, CTB suppressed these responses. TCI with either CT or CTB led to an increased accumulation of dendritic cells in the exposed epidermis and the underlying dermis. Thus, in contrast to CT, CTB appears to behave very differently when given by the transcutaneous as opposed to a mucosal route and the results suggest that the adjuvanticity of CT on Th1- and Th2-dependent responses induced by TCI involves two distinct moieties, the B and the A subunits, respectively.
The Role of mRNA Turnover in the Regulation of Tristetraprolin Expression: Evidence for an Extracellular Signal-Regulated Kinase-Specific, AU-Rich Element-Dependent, Autoregulatory Pathway
Authors: Brooks Seth A. , Connolly John E. , Rigby William F. C. 
Published: April 2014

Abstract
Tristetraprolin (TTP) is a regulator of TNF-α mRNA stability and is the only trans-acting factor shown to be capable of regulating AU-rich element-dependent mRNA turnover at the level of the intact animal. Using the THP-1 myelomonocytic cell line, we demonstrated for the first time that TTP is encoded by an mRNA with a short half-life under resting conditions. Using pharmacologic inhibitors of the mitogen-activated protein kinase pathways, we show that the induction of TTP by LPS activation is mediated through changes in transcription, mRNA stability, and translation. A coordinate increase in both TTP and TNF-α mRNA stability occurs within 15 min of LPS treatment, but is transduced through different mitogen-activated protein kinase pathways. This regulation of TTP and TNF-α mRNA stability is associated with the finding that TTP binds these mRNA under both resting and LPS-activated conditions in vivo. Finally, we demonstrate that TTP can regulate reporter gene expression in a TTP 3′ untranslated region-dependent manner and identify three distinct AU-rich elements necessary to mediate this effect. Thus, TTP regulates its own expression in a manner identical to that seen with the TNF-α 3′ untranslated region, indicating that this autoregulation is mediated at the level of mRNA stability. In this manner, TTP is able to limit the production of its own proteins as well as that of TNF-α and thus limit the response of the cell to LPS.
Tumor-Derived MUC1 Mucins Interact with Differentiating Monocytes and Induce IL-10highIL-12low Regulatory Dendritic Cell
Authors: Monti Paolo , Leone Biagio Eugenio , Zerbi Alessandro , Balzano Gianpaolo , Cainarca Silvia , Sordi Valeria , Pontillo Marina , Mercalli Alessia , Di Carlo Valerio , Allavena Paola , Piemonti Lorenzo 
Published: April 2014

AbstractDendritic cells (DC) initiate immunity by the activation of naive T cells and control immunity through their ability to induce unresponsiveness of lymphocytes by mechanisms that include deletion and induction of regulatory cells. An inadequate presentation to T cells by tumor-induced “regulatory” DC, among several mechanisms, can explain tolerance to tumor-associated Ags. In this study, we show that tumor-derived mucin profoundly affects the cytokine repertoire of monocyte-derived DC and switch them into IL-10highIL-12low regulatory APCs with a limited capacity to trigger protective Th1 responses. In fact, DC cocultured with pancreatic tumor cell lines in a Transwell system did not reach full maturation, had low immunostimulatory functions, did not produce IL-12, and released high levels of IL-10. The involvement of known tumor-derived immune-suppressive factors (e.g., vascular endothelial growth factor, TGF-β, IL-6, and IL-10) was considered and excluded. We provide evidence that tumor-derived MUC1 mucins are responsible for the impaired DC maturation and function. DC obtained in the presence of tumor microenvironment preferentially polarized IL-4+ response. Moreover, T cells primed by these regulatory DC became anergic and behaved as suppressor/regulatory cells. These findings identify mucin secretion as a novel mechanism of tumor escape from immune surveillance and provide the basis for the generation of potentially tolerogenic DC.
CD4−CD8αα Subset of CD1d-Restricted NKT Cells Controls T Cell Expansion
Authors: Ho Ling-Pei , Urban Britta C. , Jones Louise , Ogg Graham S. , McMichael Andrew J. 
Published: April 2014

Abstract
Vα24 invariant (Vα24i) CD1d-restricted NKT cells are widely regarded to have immune regulatory properties. They are known to have a role in preventing autoimmune diseases and are involved in optimally mounted immune responses to pathogens and tumor cells. We were interested in understanding how these cells provide protection in autoimmune diseases. We first observed, using EBV/MHC I tetrameric complexes, that expansion of Ag-specific cells in human PBMCs was reduced when CD1d-restricted NKT cells were concomitantly activated. This was accompanied by an increase in a CD4−CD8αα+ subset of Vα24i NKT cells. To delineate if a specific subset of NKT cells was responsible for this effect, we generated different subsets of human CD4− and CD4+ Vα24i NKT clones and demonstrate that a CD4−CD8αα+ subset with highly efficient cytolytic ability was unique among the clones in being able to suppress the proliferation and expansion of activated T cells in vitro. Activated clones were able to kill CD1d-bearing dendritic or target cells. We suggest that one mechanism by which CD1d-restricted NKT cells can exert a regulatory role is by containing the proliferation of activated T cells, possibly through timely lysis of APCs or activated T cells bearing CD1d.
On the Relevance of TCR Rearrangement Circles as Molecular Markers for Thymic Output during Experimental Graft-versus-Host Disease
Authors: Krenger Werner , Schmidlin Heike , Cavadini Gionata , Holländer Georg A. 
Published: April 2014

Abstract
Efficient reconstitution of the pool of peripheral T cells after hemopoietic stem cell transplantation (HSCT) is dependent on normal thymic function. However, the development of graft-vs-host disease (GVHD) in the context of allogeneic HSCT is associated with injurious effects on thymocyte development. In this study, we examined in models of syngeneic and allogeneic murine HSCT whether actual posttransplant thymic output is accurately reflected by analysis of signal-joint TCR rearrangement excision circles (sjTRECs). Our data demonstrate that the de novo generation of T cells following syngeneic HSCT of T cell-deficient B6.RAG2−/− (recombination-activating gene 2−/−) mice correlates firmly with an increase of sjTRECs in the thymus and spleen. However, the altered homeostasis of naive peripheral T cells in the presence of GVHD necessitates the combined analysis of cell division in vivo and determinations of sjTREC contents and total sjTREC numbers to draw informative conclusions. From our data, we substantiate that thymic output and peripheral division of newly generated T cells are diminished in the presence of acute GVHD in an experimental radiation/allogeneic HSCT model.
A Two-Step Model of Acute CD4 T-Cell Mediated Cardiac Allograft Rejection
Authors: Grazia Todd J. , Pietra Biagio A. , Johnson Zachary A. , Kelly Brian P. , Plenter Robert J. , Gill Ronald G. 
Published: April 2014

Abstract
CD4 T cells are both necessary and sufficient to mediate acute cardiac allograft rejection in mice. This process requires “direct” engagement of donor MHC class II molecules. That is, acute rejection by CD4+ T cells requires target MHC class II expression by the donor and not by the host. However, it is unclear whether CD4+ T cell rejection requires MHC class II expression on donor hemopoietic cells, nonhemopoietic cells, or both. To address this issue, bone marrow transplantation in mice was used to generate chimeric heart donors in which MHC class II was expressed either on somatic or on hemopoietic cells. We report that direct recognition of hemopoietic and nonhemopoietic cells are individually rate limiting for CD4+ T cell-mediated rejection in vivo. Importantly, active immunization with MHC class II+ APCs triggered acute rejection of hearts expressing MHC class II only on the somatic compartment. Thus, donor somatic cells, including endothelial cells, are not sufficient to initiate acute rejection; but they are necessary as targets of direct alloreactive CD4 T cells. Taken together, results support a two-stage model in which donor passenger leukocytes are required to activate the CD4 response while direct interaction with the somatic compartment is necessary for the efferent phase of acute graft rejection.
The Electrostatic Nature of C3d-Complement Receptor 2 Association
Authors: Morikis Dimitrios , Lambris John D. 
Published: April 2014

AbstractThe association of complement component C3d with B or T cell complement receptor 2 (CR2 or CD21) is a link between innate and adaptive immunity. It has been recognized in experimental studies that the C3d-CR2 association is pH- and ionic strength-dependent. This led us to perform electrostatic calculations to obtain a theoretical understanding of the mechanism of C3d-CR2 association. We used the crystallographic structures of human free C3d, free CR2 (short consensus repeat (SCR)1–2), and the C3d-CR2(SCR1–2) complex, and continuum solvent representation, to obtain a detailed atomic-level picture of the components of the two molecules that contribute to association. Based on the calculation of electrostatic potentials for the free and bound species and apparent pKa values for each ionizable residue, we show that C3d-CR2(SCR1–2) recognition is electrostatic in nature and involves not only the association interface, but also the whole molecules. Our results are in qualitative agreement with experimental data that measured the ionic strength and pH dependence of C3d-CR2 association. Also, our results for the native molecules and a number of theoretical mutants of C3d explain experimental mutagenesis studies of amino acid replacements away from the association interface that modulate binding of iC3b with full-length CR2. Finally, we discuss the packing of the two SCR domains. Overall, our data provide global and site-specific explanations of the physical causes that underlie the ionic strength dependence of C3d-CR2 association in a unified model that accounts for all experimental data, some of which were previously thought to be contradictory.
Akt Decreases Lymphocyte Apoptosis and Improves Survival in Sepsis
Authors: Bommhardt Ursula , Chang Katherine C. , Swanson Paul E. , Wagner Tracey H. , Tinsley Kevin W. , Karl Irene E. , Hotchkiss Richard S. 
Published: April 2014

Abstract
Sepsis induces extensive death of lymphocytes that may contribute to the immunosuppression and mortality of the disorder. The serine/threonine kinase Akt is a key regulator of cell proliferation and death. The purpose of this study was to determine whether overexpression of Akt would prevent lymphocyte apoptosis and improve survival in sepsis. In addition, given the important role of Akt in cell signaling, T cell Th1 and Th2 cytokine production was determined. Mice that overexpress a constitutively active Akt in lymphocytes were made septic, and survival was recorded. Lymphocyte apoptosis and cytokine production were determined at 24 h after surgery. Mice with overexpression of Akt had a marked improvement in survival compared with wild-type littermates, i.e., 94 and 47% survival, respectively, p &lt; 0.01. In wild-type littermates, sepsis caused a marked decrease in IFN-γ production, while increasing IL-4 production &gt;2-fold. In contrast, T cells from Akt transgenic mice had an elevated production of IFN-γ at baseline that was maintained during sepsis, while IL-4 had little change. Akt overexpression also decreased sepsis-induced lymphocyte apoptosis via a non-Bcl-2 mechanism. In conclusion, Akt overexpression in lymphocytes prevents sepsis-induced apoptosis, causes a Th1 cytokine propensity, and improves survival. Findings from this study strengthen the concept that a major defect in sepsis is impairment of the adaptive immune system, and suggest that strategies to prevent lymphocyte apoptosis represent a potential important new therapy.
Following Immunization Antigen Becomes Concentrated in a Limited Number of APCs Including B Cells
Authors: Byersdorfer Craig A. , DiPaolo Richard J. , Petzold Shirley J. , Unanue Emil R. 
Published: April 2014

AbstractImmunization with the hen egg-white lysozyme (HEL) protein induces T cells to various of its peptide determinants. The distribution of such T cells, however, does not correlate with the peptide level of each epitope on class II molecules. For this reason, we sought information on the cells responsible for Ag presentation following immunization, hoping to understand the lack of immunodominance in this system. By tracking HEL, and the ensuing peptide/MHC complexes, we find the following: 1) that HEL in the draining lymph node gets concentrated in a limited number of APC, particularly in dendritic cells and macrophages, 2) that these APC are functionally capable of presenting both major and minor determinants of HEL over a 100-fold range of Ag dose, and 3) that B cells present Ag gained at early times after immunization, but only following higher dose immunization. These data indicate that the breadth of a response is maintained over a wide dosage range by concentration of Ag in a limited number of cells presenting high levels and a great diversity of epitopes.
Immunity to the Extracellular Domain of Nogo-A Modulates Experimental Autoimmune Encephalomyelitis
Authors: Fontoura Paulo , Ho Peggy P. , DeVoss Jason , Zheng Binhai , Lee Byung J. , Kidd Brian A. , Garren Hideki , Sobel Raymond A. , Robinson William H. , Tessier-Lavigne Marc , Steinman Lawrence 
Published: April 2014

Abstract
Nogo-66, the extracellular 66 aa loop of the Nogo-A protein found in CNS myelin, interacts with the Nogo receptor and has been proposed to mediate inhibition of axonal regrowth. It has been shown that immunization with Nogo-A promotes recovery in animal models of spinal cord injury through induction of Ab production. In this report, studies were performed to characterize the immune response to Nogo-66 and to determine the role of Nogo in experimental autoimmune encephalomyelitis (EAE). Immunization of EAE-susceptible mouse strains with peptides derived from Nogo-66 induced a CNS immune response with clinical and pathological similarities to EAE. The Nogo-66 peptides elicited strong T cell responses that were not cross-reactive to other encephalitogenic myelin Ags. Using a large scale spotted microarray containing proteins and peptides derived from a wide spectrum of myelin components, we demonstrated that Nogo-66 peptides also generated a specific Ab response that spreads to several other encephalitogenic myelin Ags following immunization. Nogo-66-specific T cell lines ameliorated established EAE, via Nogo-66-specific Th2 cells that entered the CNS. These results indicate that some T cell and B cell immune responses to Nogo-66 are associated with suppression of ongoing EAE, whereas other Nogo-66 epitopes can be encephalitogenic.