bluuebunny/crossref_metadata_2025_split huggingface dataset:
Prolonged Exposure of T Cells to TNF Down-Regulates TCRζ and Expression of the TCR/CD3 Complex at the Cell Surface
Authors: Isomäki Pia , Panesar Manvinder , Annenkov Alex , Clark Joanna M. , Foxwell Brian M. J. , Chernajovsky Yuti , Cope Andrew P. 
Published: April 2014

Abstract
A role for TNF-α in the pathogenesis of chronic inflammatory disease is now firmly established. Paradoxically, TNF also has potent immunomodulatory effects on CD4+ T lymphocytes, because Ag-specific proliferative and cytokine responses are suppressed following prolonged exposure to TNF. We explored whether TNF attenuated T cell activation by uncoupling proximal TCR signal transduction pathways using a mouse T cell hybridoma model. Chronic TNF exposure induced profound, but reversible, T cell hyporesponsiveness, with TNF-treated T cells requiring TCR engagement with higher peptide concentrations for longer periods of time for commitment to IL-2 production. Subsequent experiments revealed that chronic TNF exposure led to a reversible loss of TCRζ chain expression, in part through a reduction in gene transcription. Down-regulation of TCRζ expression impaired TCR/CD3 assembly and expression at the cell surface and uncoupled membrane-proximal tyrosine phosphorylation events, including phosphorylation of the TCRζ chain itself, CD3ε, ZAP-70 protein tyrosine kinase, and linker for activation of T cells (LAT). Intracellular Ca2+ mobilization was also suppressed in TNF-treated T cells. We propose that TNF may contribute to T cell hyporesponsiveness in chronic inflammatory and infectious diseases by mechanisms that include down-regulation of TCRζ expression. We speculate that by uncoupling proximal TCR signals TNF could also interrupt mechanisms of peripheral tolerance that are dependent upon intact TCR signal transduction pathways.
Essential Requirement of Antigen Presentation by Monocyte Lineage Cells for the Activation of Primary Human γδ T Cells by Aminobisphosphonate Antigen
Authors: Miyagawa Fumi , Tanaka Yoshimasa , Yamashita Seiji , Minato Nagahiro 
Published: April 2014

Abstract
Human γδ T cells respond to nonpeptide Ags such as pyrophosphomonoesters and alkylamines in a γδ TCR-dependent manner in the absence of other APCs. Recently, aminobisphosphonates such as pamidronate have also been shown to activate human γδ T cells. In the present study, we indicate that activation of primary γδ T cells by pamidronate strictly depends on the presence of monocyte-lineage cells, unlike that by pyrophosphomonoesters. Thus, although pamidronate induced cell clustering, proliferation, and IFN-γ production of γδ T cells in the culture of PBMC, it failed to induce any of these activities in the culture of purified primary γδ T cells. By adding back the purified monocytes, however, both cell clustering and IFN-γ production of γδ T cells by pamidronate could be restored. The pamidronate-pulsed, but not untreated, myelomonocytic line, THP-1, was capable of activating the purified γδ T cells to produce IFN-γ, which was associated with the down-regulation of γδ TCR. Furthermore, pamidronate-pulsed THP-1 cells were significantly more susceptible to γδ T cell-mediated cytotoxicity than untreated THP-1. Also, TCR-defective Jurkat T cells transfected with γδ TCR genes produced a significant level of IL-2 in response to the pamidronate-pulsed THP-1 cells. These results have suggested strongly that human γδ T cells are functionally activated via γδ TCR by aminobisphosphonate Ag presented on the surface of monocyte lineage cells rather than directly by its free form .
IL-12 Enhances CD8 T Cell Homeostatic Expansion
Authors: Kieper William C. , Prlic Martin , Schmidt Clint S. , Mescher Matthew F. , Jameson Stephen C. 
Published: April 2014

Abstract
The size of the T lymphocyte pool is maintained by regulation of T cell production, proliferation, and survival. Under the pressure of a T lymphopenic environment, mature naive T cells begin to proliferate in the absence of Ag, a process called homeostatic expansion. Homeostatic expansion involves TCR recognition of self peptide/MHC ligands, but less is known about the soluble factors that regulate this process. Here we show that IL-12 dramatically enhanced the homeostatic proliferation of CD8 T cells. In contrast, IL-2 had no beneficial effect on homeostatic expansion and, in fact, inhibited T cell expansion induced by IL-12. Using gene-targeted mice, we showed that IL-12 acted directly on the T cells to enhance homeostatic expansion, but that IL-12 cannot override the requirement for TCR interaction with self peptide/MHC ligands in homeostatic expansion. These data indicate that inflammatory cytokines may modulate T cell homeostasis after lymphopenia and have implications for regulation of the T cell repertoire and autoimmunity.
Lymphocyte Lineages at Mucosal Effector Sites: Rat Salivary Glands
Authors: O’Sullivan Nancy L. , Skandera Cheryl A. , Montgomery Paul C. 
Published: April 2014

Abstract
Development of T cell lineages and the role of the thymus as a source of immature T cells in parotid (PG) and submandibular salivary glands (SMG) were studied in Fischer 344 rats using the Thy-1/CD45RC/RT6 expression model. In addition, the phenotypes of salivary gland lymphocytes were compared with other conventional and extrathymic populations. PG mononuclear cells consisted of T cells (38%), B cells (29%), and NK cells (4%). SMG had 19% T cells, 7% B cells, 37% NK cells, and an unusual population of CD3−/RT6+ cells. In comparison with lymph node (LN), both PG and SMG were enriched in immature (Thy-1+) and activated (Thy-1−/CD45RC−/RT6−) T cells. Unchanged percentages of Thy-1+ T cells in PG and SMG following short-term adult thymectomy indicated that immature salivary gland T cells had an extrathymic source. In contrast, thymectomy eliminated LN recent thymic emigrants. SMG had T cells with characteristics of extrathymic populations, expressing TCRγδ+ (28%), the CD8αα homodimer (11%), and NKR-P1A (66%). Many SMG T cells expressed integrin αEβ7. PG T cells resembled those isolated from LN in respect to TCR and CD8 isoform usage, but were enriched in αEβ7+ T cells and in NKT cells. Thus, salivary gland mononuclear cells are composed of a variety of subpopulations whose distributions differ between SMG and PG and are distinct from LN. These studies provide a basis for further investigation of regionalization in the mucosal immune network and are relevant to the design of vaccine regimens and intervention during pathological immune processes.
IFN-α and IL-10 Induce the Differentiation of Human Type 1 T Regulatory Cells
Authors: Levings Megan K. , Sangregorio Romina , Galbiati Francesca , Squadrone Stefania , de Waal Malefyt Rene , Roncarolo Maria-Grazia 
Published: April 2014

Abstract
CD4+ T regulatory type 1 (Tr1) cells suppress Ag-specific immune responses in vitro and in vivo. Although IL-10 is critical for the differentiation of Tr1 cells, the effects of other cytokines on differentiation of naive T cells into Tr1 cells have not been investigated. Here we demonstrate that endogenous or exogenous IL-10 in combination with IFN-α, but not TGF-β, induces naive CD4+ T cells derived from cord blood to differentiate into Tr1 cells: IL-10+IFN-γ+IL-2−/lowIL-4−. Naive CD4+ T cells derived from peripheral blood require both exogenous IL-10 and IFN-α for Tr1 cell differentiation. The proliferative responses of the Tr1-containing lymphocyte populations, following activation with anti-CD3 and anti-CD28 mAbs, were reduced. Similarly, cultures containing Tr1 cells displayed reduced responses to alloantigens via a mechanism that was partially mediated by IL-10 and TGF-β. More importantly, Tr1-containing populations strongly suppressed responses of naive T cells to alloantigens. Collectively, these results show that IFN-α strongly enhances IL-10-induced differentiation of functional Tr1 cells, which represents a first major step in establishing specific culture conditions to generate T regulatory cells for biological and biochemical analysis, and for cellular therapy to induce peripheral tolerance in humans.
Differential Roles of Lck and Itk in T Cell Response to Antigen Recognition Revealed by Calcium Imaging and Electron Microscopy
Authors: Donnadieu Emmanuel , Lang Valérie , Bismuth Georges , Ellmeier Wilfried , Acuto Oreste , Michel Frédérique , Trautmann Alain 
Published: April 2014

Abstract
Ag recognition triggered at the interface between a T cell and an APC is conditioned by cell-cell adhesion and cytoskeletal remodeling. The role played in these phenomena by Lck and Itk, two protein tyrosine kinases essential for T cell signaling, was examined. Early T cell responses (membrane ruffling, Ca2+ response, APC-T cell adhesion) were monitored in T cells overexpressing kinase-defective (KD) Lck and Itk mutants by combining fluorescence imaging and electron microscopy. Neither Lck nor Itk appears to be involved in the Ag-independent formation of a small and labile contact interface between T cells and APCs. By contrast, the Ag-induced Ca2+ response in a cell population is similarly blunted in both KD transfectants. However, the underlying mechanisms are strikingly different for the two kinases. The major effect of Lck-KD is to reduce the probability of giving rise to quasi-normal Ca2+ responses, whereas overexpression of Itk-KD results in a tuning down of all single-cell Ca2+ responses. In addition, Lck, but not Itk, is required for the formation of a stable T/APC conjugate and for T cell polarization after Ag stimulation. Overall, our results lead to a clear distinction between Lck and Itk. Lck plays an ignition role, controlling all the downstream events tested here, whereas Itk amplifies the Ca2+ response, but is dispensable for APC-induced adhesive and morphological responses.
The Vasodilator-Stimulated Phosphoprotein Is Regulated by Cyclic GMP-Dependent Protein Kinase During Neutrophil Spreading
Authors: Lawrence Donald W. , Pryzwansky Katherine B. 
Published: April 2014

Abstract
The expression and phosphorylation state of the vasodilator-stimulated phosphoprotein (VASP), a membrane-associated focal adhesion protein, was investigated in human neutrophils. Adhesion and spreading of neutrophils induced the rapid phosphorylation of VASP. The phosphorylation of VASP was dependent on cell spreading, as VASP was expressed as a dephosphorylated protein in round adherent cells and was phosphorylated at the onset of changes in cell shape from round to spread cells. Immunofluorescence microscopy demonstrated that VASP was localized at the cell cortex in round cells and redistributed to focal adhesions at the ventral surface of the cell body during cell spreading. Dual labeling of spread cells indicated that VASP was colocalized with F-actin in filopodia and in focal adhesions, suggesting that the phosphorylation of VASP during cell spreading may be involved in focal adhesion complex organization and actin dynamics. VASP is a prominent substrate for both cGMP-dependent protein kinase (cGK) and cAMP-dependent protein kinase. Evidence suggested that cGK regulated neutrophil spreading, as both VASP phosphorylation and neutrophil spreading were inhibited by Rp-8-pCPT-cGMPS (cGK inhibitor), but not KT5720 (cAMP-dependent protein kinase inhibitor). In contrast, neutrophil spreading was accelerated when cGMP levels were elevated with 8-Br-cGMP, a direct activator of cGK. Furthermore, the same conditions that lead to VASP phosphorylation during neutrophil adherence and spreading induced significant elevations of cGMP in neutrophils. These results indicate that cGMP/cGK signal transduction is required for neutrophil spreading, and that VASP is a target for cGK regulation.
Tumor Progression Despite Efficient Tumor Antigen Cross-Presentation and Effective “Arming” of Tumor Antigen-Specific CTL
Authors: Nelson Delia J. , Mukherjee Sutapa , Bundell Christine , Fisher Scott , van Hagen Deborah , Robinson Bruce 
Published: April 2014

Abstract
To determine whether APC function or “arming” of CTL for lytic function are the points at which Ags from a nonimmunogenic tumor fail to induce an effective immune response, we established a murine tumor model that expressed intracellular OVA and selected a clone (cOVA-9) that remained susceptible to lysis by specific CD8+ T cells throughout tumor growth. Viable cOVA-9 tumor cells grew in normal mice at a rate similar to the parental tumor, and vaccination with irradiated cOVA-9 cells did not induce protection against itself or the parental line, confirming its nonimmunogenic status. In vivo evaluation during tumor growth demonstrated persisting tumor Ag cross-presentation accompanied by the generation of potent, specific CTL which were detectable when tumors were barely palpable. Despite the presence of highly active CTL in the tumor-draining lymph nodes, there was no apparent lysis of tumor-associated APC. These data show that tumor-draining APC are not dysfunctional with regard to two crucial processes, in vivo tumor Ag cross-presentation and specific CTL arming, and that failure to prevent tumor growth is not in the induction phase, but in the effector phase and occurs within the tumor itself before the tumor matrix is established.
CD24 Induces Apoptosis in Human B Cells Via the Glycolipid-Enriched Membrane Domains/Rafts-Mediated Signaling System
Authors: Suzuki Toyo , Kiyokawa Nobutaka , Taguchi Tomoko , Sekino Takaomi , Katagiri Yohko U. , Fujimoto Junichiro 
Published: April 2014

AbstractThe glycosylphosphatidylinositol-anchored CD24 protein is a B cell differentiation Ag that is expressed on mature resting B cells but disappears upon Ag stimulation. We used Burkitt’s lymphoma (BL) cells, which are thought to be related to germinal center B cells, to examine the biological effect of Ab-mediated CD24 cross-linking on human B cells and observed 1) induction of apoptosis in BL cells mediated by cross-linking of CD24; and 2) synergism between the cross-linking of CD24 and that of the B cell receptor for Ag in the effect on apoptosis induction. We also observed activation of mitogen-activated protein kinases following CD24 cross-linking, suggesting that CD24 mediates the intracellular signaling that leads to apoptosis in BL cells. Although CD24 has no cytoplasmic portion to transduce signals intracellularly, analysis of biochemically separated glycolipid-enriched membrane (GEM) fractions indicated enhanced association of CD24 and Lyn protein tyrosine kinase in GEM as well as increased Lyn kinase activity after CD24 cross-linking, suggesting that CD24 mediates intracellular signaling via a GEM-dependent mechanism. Specific microscopic cocapping of CD24 and Lyn, but not of other kinases, following CD24 cross-linking supported this idea. We further observed that apoptosis induction by cross-linking is a common feature shared by GEM-associated molecules expressed on BL cells, including GPI-anchored proteins and glycosphingolipids. CD24-mediated apoptosis in BL cells may provide a model for the cell death mechanism initiated by GEM-associated molecules, which is closely related to B cell receptor for Ag-mediated apoptosis.
Stimulatory Effects of B7-Related Protein-1 on Cellular and Humoral Immune Responses in Mice
Authors: Guo Jane , Stolina Marina , Bready James V. , Yin Songmei , Horan Tom , Yoshinaga Steven K. , Senaldi Giorgio 
Published: April 2014

Abstract
Inducible costimulator (ICOS) and B7-related protein-1 (B7RP-1) constitute a receptor-ligand pair involved in T cell costimulation. In this study, the stimulatory effects of B7RP-1 on cellular and humoral immune responses were investigated giving mice a construct with the extracellular domain of murine B7RP-1 fused with human IgG1 Fc (B7RP-1-Fc). B7RP-1-Fc stimulated contact hypersensitivity (CH) given near either the time of sensitization or challenge with oxazolone. When given near challenge time, B7RP-1-Fc stimulated CH more than a construct containing the extracellular domain of murine B7.2 and Fc (B7.2-Fc). B7RP-1-Fc increased the number of cells in lymph nodes draining the skin sensitized with oxazolone, especially activated T cells. B7RP-1-Fc also increased the ability of the cells in these lymph nodes to induce CH when transfused into naive mice. B7RP-1-Fc stimulated the production of anti-keyhole limpet hemocyanin (KLH) Ab, increasing anti-KLH IgG, IgG2a, and IgE, whereas B7.2-Fc did not affect this production. B7RP-1-Fc also increased the number of cells in lymph nodes draining the skin immunized with KLH and their production of IFN-γ, IL-4, and IL-10 in response to KLH. Finally, B7RP-1-Fc increased the presence of eosinophils in the bronchoalveolar lavage and lungs of mice sensitized and challenged with OVA so to mount an asthmatic reaction. B7RP-1-Fc stimulates both cellular and humoral immune responses in vivo by increasing number and function of T and B cells reacting to Ag exposure.
Fcα Receptor Cross-Linking Causes Translocation of Phosphatidylinositol-Dependent Protein Kinase 1 and Protein Kinase Bα to MHC Class II Peptide-Loading-Like Compartments
Authors: Lang Mark L. , Shen Li , Gao Hong , Cusack William F. , Lang Gillian A. , Wade William F. 
Published: April 2014

Abstract
A20 IIA1.6 B cells cotransfected with FcαR and wild-type γ-chain (wt-ITAM (immunoreceptor tyrosine-based activation motif)) or FcαR and γ-chain, in which the wt-ITAM was substituted with the FcγRIIA ITAM (IIA-ITAM), were used to investigate cell signaling events influencing presentation of FcαR-targeted exogenous Ag in the context of MHC class II. wt-ITAM cells presented FcαR-targeted OVA more efficiently than IIA-ITAM transfectants to OVA-specific T cell hybridomas. Phosphatidylinositol 3-kinase (PI 3-kinase) inhibition abrogated Ag presentation, suggesting that FcαR may trigger a PI 3-kinase-dependent signal transduction pathway, and thus phosphatidylinositol-dependent protein kinase (PDK1) and protein kinase B α (PKBα) activation. Cross-linking FcαR on wt-ITAM or IIA-ITAM cells triggered equivalent PI 3-kinase-dependent activation of PKBα. Furthermore, FcαR cross-linking triggered recruitment of PDK1 and serine-phosphorylated PKBα to capped cell surface FcαR irrespective of the γ-chain ITAM. Although FcαR endocytosis was accompanied by translocation of PDK1 and phospho-PKBα to FcαR-containing vesicles in both transfectants, this was decreased in IIA-ITAM cells, and a significant proportion of PDK1 and PKBα remained at the plasma membrane. In wt-ITAM cells, PDK1 and serine-phosphorylated PKBα translocated to lysosomal-associated membrane glycoprotein 1- and cathepsin B-containing vesicles, consistent with MHC class II peptide-loading compartments (MIIC) described by other groups. Our data indicate that translocation of signal transduction mediators to MIIC-like compartments accompanies efficient presentation of receptor-targeted Ag, and suggest a mechanism connecting signaling to the Ag-processing pathway.
Neonatal Exposure to Antigen Induces a Defective CD40 Ligand Expression that Undermines Both IL-12 Production by APC and IL-2 Receptor Up-Regulation on Splenic T Cells and Perpetuates IFN-γ-Dependent T Cell Anergy
Authors: Min Booki , Legge Kevin L. , Bell J. Jeremiah , Gregg Randal K. , Li Lequn , Caprio Jacque C. , Zaghouani Habib 
Published: April 2014

Abstract
T cell deletion and/or inactivation were considered the leading mechanisms for neonatal tolerance. However, recent investigations have indicated that immunity develops at the neonatal stage but evolves to guide later T cell responses to display defective and/or biased effector functions. Although neonatal-induced T cell modulation provides a useful approach to suppress autoimmunity, the mechanism underlying the biased function of the T cells remains unclear. In prior studies, we found that exposure of newborn mice to Ig-PLP1, a chimera expressing the encephalitogenic proteolipid protein (PLP) sequence 139–151, induced deviated Th2 lymph node cells producing IL-4 instead of IL-2 and anergic splenic T cells that failed to proliferate or produce IFN-γ yet secreted significant amounts of IL-2. However, if assisted with IFN-γ or IL-12, these anergic splenic T cells regained full responsiveness. The consequence of such biased/defective T cells responses was protection of the mice against experimental allergic encephalomyelitis. In this study, investigations were performed to delineate the mechanism underlying the novel form of IFN-γ-dependent splenic anergy. Our findings indicate that CD40 ligand expression on these splenic T cells is defective, leading to noneffective cooperation between T lymphocytes and APCs and a lack of IL-12 production. More striking, this cellular system revealed a requirement for IL-2R expression for CD40 ligand-initiated, IL-12-driven progression of T cells into IFN-γ production.
Antigen Recognition and Immunomodulation by γδ T Cells in Bovine Tuberculosis
Authors: Rhodes Shelley G. , Hewinson R. Glyn , Vordermeier H. Martin 
Published: April 2014

Abstract
This report describes the in vitro proliferative responses of peripheral blood γδ T cells to defined mycobacterial protein Ags and the immunomodulatory effect of γδ T cells in cattle infected with Mycobacterium bovis. γδ T cell responses were specific to M. bovis infection because they were detected in cattle either experimentally or naturally infected with M. bovis, but were not present in uninfected controls. Proliferating γδ T cell cultures produced enhanced levels of IFN-γ and TGF-β, but not IL-2 in response to the more immunodominant mycobacterial Ags. Depletion of γδ T cells from PBMC resulted in an increased Ag-specific proliferation in half the animals tested, indicating a suppressive effect of γδ T cells upon other (αβ) T cell responses. Because γδ T cells constitute a major T cell population in the peripheral blood of cattle, the activities of γδ T cells described in this report could make a significant contribution to the immune response in bovine tuberculosis.
Sanglifehrin A, a Novel Cyclophilin-Binding Immunosuppressant, Inhibits IL-2-Dependent T Cell Proliferation at the G1 Phase of the Cell Cycle
Authors: Zhang Ling-Hua , Liu Jun O. 
Published: April 2014

Abstract
Sanglifehrin A (SFA) is a novel immunosuppressive natural product that binds to cyclophilin but is structurally distinct from cyclosporin A (CsA). We have investigated the cellular and molecular mechanisms of the action of SFA in T lymphocytes. We show that SFA inhibits T cell proliferation induced by IL-2 with an IC50 of 200 nM. Distinct from CsA, which also binds to cyclophilin, SFA does not affect calcium-dependent IL-2 production, although SFA enhanced IL-2 gene transcription in the same cells. SFA blocks T cell proliferation induced by IL-2 in G1 with no appreciable effect on IL-2 receptor expression in a manner similar to that of the immunosuppressant rapamycin. Unlike rapamycin, however, SFA has no effect on the phosphorylation or enzymatic activity of p70s6k kinase, distinguishing SFA from rapamycin in their mode of action. SFA inhibits hyperphosphorylation of Rb and the activity of cyclin E-cyclin-dependent kinase 2 on IL-2 signaling. These results suggest that SFA has a novel mode of action in comparison with CsA, FK506, and rapamycin, and that its use as a molecular probe may lead to the discovery of a novel target involved in T cell activation.