bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Host Environment Regulates the Function of CD8+ Graft-versus-Host-Reactive Effector Cells
Authors: Chakraverty Ronjon , Flutter Barry , Fallah-Arani Farnaz , Eom Hyeon-Seok , Means Terry , Andreola Giovanna , Schwarte Sebastian , Buchli Jennifer , Cotter Pete , Zhao Guiling , Sykes Megan 
Published: April 2014

AbstractWe have examined how the host environment influences the graft-vs-leukemia (GVL) response following transfer of donor T cells to allogeneic chimeras. Donor T cells induce significant GVL when administered in large numbers to established mixed chimeras (MC). However, when using limiting numbers of T cells, we found that late transfer to MC induced less GVL than did early transfer to freshly irradiated allogeneic recipients. Late donor T cell transfer to MC was associated with marked accumulation of anti-host CD8 cells within the spleen, but delayed kinetics of differentiation, reduced expression of effector molecules including IFN-γ, impaired cytotoxicity, and higher rates of sustained apoptosis. Furthermore, in contrast to the spleen, we observed a significant delay in donor CD8 cell recruitment to the bone marrow, a key location for hematopoietic tumors. Increasing the numbers of T cells transferred to MC led to the enhancement of CTL activity and detectable increases in absolute numbers of IFN-γ+ cells without inducing graft-vs-host disease (GVHD). TLR-induced systemic inflammation accelerated differentiation of functional CTL in MC but was associated with severe GVHD. In the absence of inflammation, both recipient T and non-T cell populations impeded the full development of GVHD-inducing effector function. We conclude that per-cell deficits in the function of donor CD8 cells activated in MC may be overcome by transferring larger numbers of T cells without inducing GVHD.
MHC Variant Peptide-Mediated Anergy of Encephalitogenic T Cells Requires SHP-1
Authors: Wasserman Heather A. , Beal Carrie D. , Zhang Yan , Jiang Ning , Zhu Cheng , Evavold Brian D. 
Published: April 2014

AbstractOur lab has demonstrated that encephalitogenic T cells can be effectively anergized by treatment with MHC variant peptides, which are analogues of immunogenic peptides containing an amino acid substitution at an MHC anchor residue. The MHC variant peptide of myelin oligodendrocyte glycoprotein (MOG)35–55 proves an effective treatment as it does not induce symptoms of experimental autoimmune encephalomyelitis and fails to recruit macrophages or MOG35–55-specific T cells to the CNS. In this study, we sought to characterize the signaling pathways required for the induction of anergy by building upon the observations identifying the tyrosine phosphatase SHP-1 as a critical regulator of T cell responsiveness. Motheaten viable heterozygous mice, which contain a mutation in the SHP-1 gene resulting in a reduction in functional SHP-1, were challenged with MOG35–55 or the MOG35–55 MHC variant 45D. These mice display symptoms of experimental autoimmune encephalomyelitis upon immunization with MHC variant peptide and have significant CNS infiltration of tetramer-positive CD4+ cells and macrophages, unlike B6 mice challenged with the variant peptide. The effects of SHP-1 are directly on the T cell as Motheaten viable heterozygous mice autoreactive T cells are not anergized in vitro. Lastly, we demonstrate no distinguishable difference in the initial interaction between the TCR and agonist or MHC variant. Rather, an unstable interaction between peptide and MHC attenuates the T cell response, seen in a decreased half-life relative to MOG35–55. These results identify SHP-1 as a mediator of T cell anergy induced by destabilized peptide:MHC complexes.
Polysialic Acid, a Glycan with Highly Restricted Expression, Is Found on Human and Murine Leukocytes and Modulates Immune Responses
Authors: Drake Penelope M. , Nathan Jay K. , Stock Christina M. , Chang Pamela V. , Muench Marcus O. , Nakata Daisuke , Reader J. Rachel , Gip Phung , Golden Kevin P. K. , Weinhold Birgit , Gerardy-Schahn Rita , Troy Frederic A. , Bertozzi Carolyn R. 
Published: April 2014

Abstract
Polysialic acid (polySia) is a large glycan with restricted expression, typically found attached to the protein scaffold neural cell adhesion molecule (NCAM). PolySia is best known for its proposed role in modulating neuronal development. Its presence and potential functions outside the nervous systems are essentially unexplored. Herein we show the expression of polySia on hematopoietic progenitor cells, and demonstrate a role for this glycan in immune response using both acute inflammatory and tumor models. Specifically, we found that human NK cells modulate expression of NCAM and the degree of polymerization of its polySia glycans according to activation state. This contrasts with the mouse, where polySia and NCAM expression are restricted to multipotent hematopoietic progenitors and cells developing along a myeloid lineage. Sialyltransferase 8Sia IV−/− mice, which lacked polySia expression in the immune compartment, demonstrated an increased contact hypersensitivity response and decreased control of tumor growth as compared with wild-type animals. This is the first demonstration of polySia expression and regulation on myeloid cells, and the results in animal models suggest a role for polySia in immune regulation.
Antiviral-Activated Dendritic Cells: A Paracrine-Induced Response State
Authors: Bordería Antonio V. , Hartmann Boris M. , Fernandez-Sesma Ana , Moran Thomas M. , Sealfon Stuart C. 
Published: April 2014

Abstract
Infection of immature dendritic cells (DCs) by virus stimulates their maturation into APC. Infected DCs can also expose uninfected DCs to a panoply of cytokines/chemokines via paracrine signaling. Mathematical modeling suggests that a high rate of paracrine signaling is likely to occur among DCs located in three-dimensional space. Relatively little is known about how secreted factors modify the early response to virus infection. We used a transwell experimental system that allows passage of secreted factors, but not direct contact, between virus-infected DCs and uninfected DCs to investigate paracrine signaling responses. Paracrine signaling from infected DCs induced an antiviral-primed DC state distinct from that of mature virus-infected DCs that we refer to as antiviral-activated DCs (AVDCs). AVDCs had increased surface MHC class II and CD86 levels, but in contrast to virus-infected DCs, their MHC class I levels were unchanged. Imaging flow cytometry showed that AVDCs had an increased rate of phagocytosis compared with naive DCs. Experiments with IFN-β cytokine indicated that it may be responsible for CD86, but not MHC class II regulation in AVDCs. Both IFN-inducible and IFN-independent genes are up-regulated in AVDCs. Notably, AVDCs are relatively resistant to virus infection in comparison to naive DCs and achieve accelerated and augmented levels of costimulatory molecule expression with virus infection. AVDCs show a distinct antiviral-primed state of DC maturation mediated by DC paracrine signaling. Although further in vivo study is needed, the characteristics of the AVDC suggest that it is well suited to play a role in the early innate-adaptive transition of the immune system.
PI4P5-Kinase Iα Is Required for Efficient HIV-1 Entry and Infection of T Cells
Authors: Barrero-Villar Marta , Barroso-González Jonathan , Cabrero J. R. , Gordón-Alonso Mónica , Álvarez-Losada Susana , Muñoz-Fernández M. A. , Sánchez-Madrid Francisco , Valenzuela-Fernández Agustín 
Published: April 2014

Abstract
HIV-1 envelope (Env) triggers membrane fusion between the virus and the target cell. The cellular mechanism underlying this process is not well known. Phosphatidylinositol 4,5-bisphosphate (PIP2) is known to be important for the late steps of the HIV-1 infection cycle by promoting Gag localization to the plasma membrane during viral assembly, but it has not been implicated in early stages of HIV-1 membrane-related events. In this study, we show that binding of the initial HIV-1 Env-gp120 protein induces PIP2 production in permissive lymphocytes through the activation of phosphatidylinositol-4-phosphate 5-kinase (PI4P5-K) Iα. Overexpression of wild-type PI4P5-K Iα increased HIV-1 Env-mediated PIP2 production and enhanced viral replication in primary lymphocytes and CEM T cells, whereas PIP2 production and HIV-1 infection were both severely reduced in cells overexpressing the kinase-dead mutant D227A (D/A)-PI4P5-K Iα. Similar results were obtained with replicative and single-cycle HIV-1 particles. HIV-1 infection was also inhibited by knockdown of endogenous expression of PI4P5-K Iα. These data indicate that PI4P5-K Iα-mediated PIP2 production is crucial for HIV-1 entry and the early steps of infection in permissive lymphocytes.
Transgenic Mice Expressing Dominant-Negative Bright Exhibit Defects in B1 B Cells
Authors: Nixon Jamee C. , Ferrell Scott , Miner Cathrine , Oldham Athenia L. , Hochgeschwender Ute , Webb Carol F. 
Published: April 2014

AbstractThe transcription factor Bright up-regulates Ig H chain production from select V region promoters and requires Bright dimerization, Bruton’s tyrosine kinase (Btk), and the Btk substrate, TFII-I, for this activity. Defects in Btk cause X-linked immunodeficiency disease in mice and humans. Btk-deficient mice exhibit decreased serum IgM production, B cell developmental blocks, absence of peritoneal B1 cells, and subnormal immune responses against Ags, including phosphorylcholine, which confer protection against Streptococcus pneumoniae. Transgenic mice expressing dominant-negative Bright share similarities with Btk-deficient mice, including decreased serum IgM, poor anti-phosphorylcholine responses, and slightly reduced numbers of mature B cells. Although dominant-negative Bright mice developed B1 B cells, these were functionally deficient in Ig secretion. These data suggest a mechanistic explanation for the abnormal responses to phosphorylcholine observed in Btk-deficient mice, and indicate that Bright functions in a subset of Btk-dependent pathways in vivo, particularly those responses dominated by B1 B cells.
CD8+CD205+ Splenic Dendritic Cells Are Specialized to Induce Foxp3+ Regulatory T Cells
Authors: Yamazaki Sayuri , Dudziak Diana , Heidkamp Gordon F. , Fiorese Christopher , Bonito Anthony J. , Inaba Kayo , Nussenzweig Michel C. , Steinman Ralph M. 
Published: April 2014

Abstract
Foxp3+CD25+CD4+ regulatory T cells (Treg) mediate immunological self-tolerance and suppress immune responses. A subset of dendritic cells (DCs) in the intestine is specialized to induce Treg in a TGF-β- and retinoic acid-dependent manner to allow for oral tolerance. In this study we compare two major DC subsets from mouse spleen. We find that CD8+ DEC-205/CD205+ DCs, but not the major fraction of CD8− DC inhibitory receptor-2 (DCIR2)+ DCs, induce functional Foxp3+ Treg from Foxp3− precursors in the presence of low doses of Ag but without added TGF-β. CD8+CD205+ DCs preferentially express TGF-β, and the induction of Treg by these DCs in vitro is blocked by neutralizing Ab to TGF-β. In contrast, CD8−DCIR2+ DCs better induce Foxp3+ Treg when exogenous TGF-β is supplied. In vivo, CD8+CD205+ DCs likewise preferentially induce Treg from adoptively transferred, Ag-specific DO11.10 RAG−/− Foxp3−CD4+ T cells, whereas the CD8−DCIR2+ DCs better stimulate natural Foxp3+ Treg. These results indicate that a subset of DCs in spleen, a systemic lymphoid organ, is specialized to differentiate peripheral Foxp3+ Treg, in part through the endogenous formation of TGF-β. Targeting of Ag to these DCs might be useful for inducing Ag-specific Foxp3+ Treg for treatment of autoimmune diseases, transplant rejection, and allergy.
Rapid and Selective Expansion of Nonclonotypic T Cells in Regulatory T Cell-Deficient, Foreign Antigen-Specific TCR-Transgenic Scurfy Mice: Antigen-Dependent Expansion and TCR Analysis
Authors: Sharma Rahul , Ju Angela Chiao-Ying , Kung John T. , Fu Shu Man , Ju Shyr-Te 
Published: April 2014

Abstract
Foreign Ag-specific TCR-transgenic (Tg) mice contain a small fraction of T cells bearing the endogenous Vβ and Vα chains as well as a population expressing an intermediate level of Tg TCR. Importantly, these minor nonclonotypic populations contain ≥99% of the CD4+Foxp3+ regulatory T cells (Treg) and, despite low overall Treg expression, peripheral tolerance is maintained. In the OT-II TCR (OVA-specific, Vβ5highVα2high) Tg scurfy (Sf) mice (OT-II Sf) that lack Treg, nonclonotypic T cells markedly expanded in the periphery but not in the thymus. Expanded T cells expressed memory/effector phenotype and were enriched in blood and inflamed lungs. In contrast, Vβ5highVα2high clonotypic T cells were not expanded, displayed the naive phenotype, and found mainly in the lymph nodes. Importantly, Vβ5neg T cells were able to transfer multiorgan inflammation in Rag1−/− recipients. T cells bearing dual TCR (dual Vβ or dual Vα) were demonstrated frequently in the Vβ5int and Vα2int populations. Our study demonstrated that in the absence of Treg, the lack of peripheral expansion of clonotypic T cells is due to the absence of its high-affinity Ag OVA. Thus, the rapid expansion of nonclonotypic T cells in OT-II Sf mice must require Ag (self and foreign) with sufficient affinity. Our study has implications with respect to the roles of Ag and dual TCR in the selection and regulation of Treg and Treg-controlled Ag-dependent T cell expansion in TCR Tg and TCR Tg Sf mice, respectively.
Imatinib Mesylate Inhibits CD4+CD25+ Regulatory T Cell Activity and Enhances Active Immunotherapy against BCR-ABL− Tumors
Authors: Larmonier Nicolas , Janikashvili Nona , LaCasse Collin James , Larmonier Claire Billerey , Cantrell Jessica , Situ Elaine , Lundeen Tamara , Bonnotte Bernard , Katsanis Emmanuel 
Published: April 2014

Abstract
Imatinib mesylate (Gleevec, STI571), a selective inhibitor of a restricted number of tyrosine kinases, has been effectively used for the treatment of Philadelphia chromosome-positive leukemias and gastrointestinal stromal tumors. Imatinib may also directly influence immune cells. Suppressive as well as stimulating effects of this drug on CD4+ and CD8+ T lymphocytes or dendritic cells have been reported. In the current study, we have investigated the influence of imatinib mesylate on CD4+CD25+FoxP3+ regulatory T cells (Treg), a critical population of lymphocytes that contributes to peripheral tolerance. Used at concentrations achieved clinically, imatinib impaired Treg immunosuppressive function and FoxP3 expression but not production of IL-10 and TGF-β in vitro. Imatinib significantly reduced the activation of the transcription factors STAT3 and STAT5 in Treg. Analysis of Treg TCR-induced signaling cascade indicated that imatinib inhibited phosphorylation of ZAP70 and LAT. Substantiating these observations, imatinib treatment of mice decreased Treg frequency and impaired their immunosuppressive function in vivo. Furthermore, imatinib mesylate significantly enhanced antitumor immune responses to dendritic cell-based immunization against an imatinib-resistant BCR-ABL negative lymphoma. The clinical applications of imatinib mesylate might thus be expanded with its use as a potent immunomodulatory agent targeting Treg in cancer immunotherapy.
Targeting CD4 Coreceptor Expression to Postselection Thymocytes Reveals That CD4/CD8 Lineage Choice Is neither Error-Prone nor Stochastic
Authors: Adoro Stanley , Erman Batu , Sarafova Sophia D. , Van Laethem François , Park Jung-Hyun , Feigenbaum Lionel , Singer Alfred 
Published: April 2014

Abstract
The mechanism by which CD4/CD8 lineage choice is coordinated with TCR specificity during positive selection remains an unresolved problem in immunology. The stochastic/selection model proposes that CD4/CD8 lineage choice in TCR-signaled CD4+CD8+ thymocytes occurs randomly and therefore is highly error-prone. This perspective is strongly supported by “coreceptor rescue” experiments in which transgenic CD4 coreceptors were ectopically expressed on thymocytes throughout their development and caused significant numbers of cells bearing MHC-II-specific TCR to differentiate into mature, CD8 lineage T cells. However, it is not known if forced coreceptor expression actually rescued positively selected thymocytes making an incorrect lineage choice or if it influenced developing thymocytes into making an incorrect lineage choice. We have now reassessed coreceptor rescue and the concept that lineage choice is highly error-prone with a novel CD4 transgene (referred to as E8I-CD4) that targets expression of transgenic CD4 coreceptors specifically to thymocytes that have already undergone positive selection and adopted a CD8 lineage fate. Unlike previous CD4 transgenes, the E8I-CD4 transgene has no effect on early thymocyte development and cannot itself influence CD4/CD8 lineage choice. We report that the E8I-CD4 transgene did in fact induce expression of functional CD4 coreceptor proteins on newly arising CD8 lineage thymocytes precisely at the point in thymic development that transgenic CD4 coreceptors would putatively rescue MHC-II-specific thymocytes that incorrectly adopted the CD8 lineage. However, the E8I-CD4 transgene did not reveal any MHC-II-selected thymocytes that adopted the CD8 lineage fate. These results demonstrate that CD4/CD8 lineage choice is neither error-prone nor stochastic.
Tetraspanins Regulate ADAM10-Mediated Cleavage of TNF-α and Epidermal Growth Factor
Authors: Arduise Cécile , Abache Toufik , Li Lei , Billard Martine , Chabanon Aurélie , Ludwig Andreas , Mauduit Philippe , Boucheix Claude , Rubinstein Eric , Le Naour François 
Published: April 2014

Abstract
Several cytokines and growth factors are released by proteolytic cleavage of a membrane-anchored precursor, through the action of ADAM (a disintegrin and metalloprotease) metalloproteases. The activity of these proteases is regulated through largely unknown mechanisms. In this study we show that Ab engagement of several tetraspanins (CD9, CD81, CD82) increases epidermal growth factor and/or TNF-α secretion through a mechanism dependent on ADAM10. The effect of anti-tetraspanin mAb on TNF-α release is rapid, not relayed by intercellular signaling, and depends on an intact MEK/Erk1/2 pathway. It is also associated with a concentration of ADAM10 in tetraspanin-containing patches. We also show that a large fraction of ADAM10 associates with several tetraspanins, indicating that ADAM10 is a component of the “tetraspanin web.” These data show that tetraspanins regulate the activity of ADAM10 toward several substrates, and illustrate how membrane compartmentalization by tetraspanins can control the function of cell surface proteins such as ectoproteases.
CD45 Down-Regulates Lck-Mediated CD44 Signaling and Modulates Actin Rearrangement in T Cells
Authors: Wong Nelson K. Y. , Lai Jacqueline C. Y. , Birkenhead Darlene , Shaw Andrey S. , Johnson Pauline 
Published: April 2014

AbstractThe tyrosine phosphatase CD45 dephosphorylates the negative regulatory tyrosine of the Src family kinase Lck and plays a positive role in TCR signaling. In this study we demonstrate a negative regulatory role for CD45 in CD44 signaling leading to actin rearrangement and cell spreading in activated thymocytes and T cells. In BW5147 T cells, CD44 ligation led to CD44 and Lck clustering, which generated a reduced tyrosine phosphorylation signal in CD45+ T cells and a more sustained, robust tyrosine phosphorylation signal in CD45− T cells. This signal resulted in F-actin ring formation and round spreading in the CD45+ cells and polarized, elongated cell spreading in CD45− cells. The enhanced signal in the CD45− cells was consistent with enhanced Lck Y394 phosphorylation compared with the CD45+ cells where CD45 was recruited to the CD44 clusters. This enhanced Src family kinase-dependent activity in the CD45− cells led to PI3K and phospholipase C activation, both of which were required for elongated cell spreading. We conclude that CD45 induces the dephosphorylation of Lck at Y394, thereby preventing sustained Lck activation and propose that the amplitude of the Src family kinase-dependent signal regulates the outcome of CD44-mediated signaling to the actin cytoskeleton and T cell spreading.
Negative Regulation of TCR Signaling by Linker for Activation of X Cells via Phosphotyrosine-Dependent and -Independent Mechanisms
Authors: Shapiro Michael J. , Nguyen Chau T. , Aghajanian Haig , Zhang Weiguo , Shapiro Virginia Smith 
Published: April 2014

Abstract
The activation of T cells and the initiation of an immune response is tightly controlled through the crosstalk of both positive and negative regulators. Two adaptors that function as negative regulators of T cell activation are adaptor in lymphocytes of unknown function X (ALX) and linker for activation of X cell (LAX). Previously, we showed that T cells from mice deficient in ALX and LAX display similar hyperresponsiveness, with increased IL-2 production and proliferation upon TCR/CD28 stimulation, and that these adaptors physically associate. In this study, we analyze the nature of the association between ALX and LAX. We demonstrate that this association occurs in the absence of TCR/CD28 signaling via a mechanism independent of both tyrosine phosphorylation of LAX and the SH2 domain of ALX. Cotransfection of ALX with LAX resulted in LAX tyrosine phosphorylation in the absence of TCR/CD28 stimulation. ALX-mediated LAX phosphorylation depends upon the ALX SH2 domain, which functions to recruit Lck to LAX. We also show that LAX, like ALX, can inhibit RE/AP reporter activation. However, in contrast to its inhibition of NFAT, the inhibition of RE/AP by LAX is independent of its tyrosine phosphorylation. Therefore, it can be concluded that inhibition of signaling events involved in T cell activation by LAX occurs through mechanisms both dependent on and independent of its tyrosine phosphorylation.
Processing of an Antigenic Sequence from IgG Constant Domains for Presentation by MHC Class II
Authors: Flobakk Morten , Rasmussen Ingunn B. , Lunde Elin , Frigstad Terje , Berntzen Gøril , Michaelsen Terje E. , Bogen Bjarne , Sandlie Inger 
Published: April 2014

AbstractTargeting of T cell epitopes to APC enhances T cell responses. We used an APC-specific Ab (anti-IgD) and substituted either of 18 loops connecting β strands in human IgG constant H (CH) domains with a characterized T cell peptide epitope. All Ab-epitope fusion molecules were secreted from producing cells except IgG-loop 2(BC)CH1, and comparing levels, a hierarchy appeared with fusions involving CH2≥CH1&gt;CH3. Within each domain, fusion at loop 6(FG) showed best secretion, while low secretion correlated with the substitution of native loops that contain conserved amino acids buried within the folded molecule. Comparing the APC-specific rAb molecules for their ability to induce T cell activation in vitro, the six mutants with epitope in CH2 were the most effective, with loop 4CH2 ranking on top. The CH1 mutants were more resistant to processing, and the loop 6CH1 mutant only induced detectable activation. The efficiency of the CH3 mutants varied, with loop 6CH3 being the least effective and equal to loop 6 CH1. Considering both rAb secretion level and T cell activation efficiency, a total of eight loops may carry T cell epitopes to APC for processing and presentation to T cells, namely, all in CH2 in addition to loop 6 in CH1 and CH3. Comparing loop 4CH2 with loop 6CH1 mutants after injection of Ab in BALB/c mice, the former was by far the most efficient and induced specific T cell activation at concentrations at least 100-fold lower than loop 6CH1.