bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Selective Role for the TNF p55 Receptor in Autocrine Signaling following IFN-γ Stimulation in Experimental Autoimmune Uveoretinitis
Authors: Calder Claudia J. , Nicholson Lindsay B. , Dick Andrew D. 
Published: April 2014

Abstract
IFN-γ stimulates macrophage activation and NO production, which leads to destruction of the retina in experimental autoimmune uveoretinitis. In this study, we investigate the mechanism of disease resistance in TNF p55 receptor-deficient animals. We show that although T cell priming is relatively unaffected, macrophages lacking the TNF p55 receptor fail to produce NO following IFN-γ stimulation because of a requirement for autocrine TNF-α signaling through the TNF p55 receptor. In contrast to the impaired activation of NO synthesis, MHC class II up-regulation was indistinguishable in wild-type and TNFRp55−/− mice stimulated with IFN-γ. These defects could be overcome by stimulating macrophages with LPS. Together, these results show that selected aspects of IFN-γ activation are controlled by autocrine secretion of TNF-α, but that this control is lost in the presence of signals generated by pathogen-associated molecular patterns recognizing receptors.
Interaction between Human NK Cells and Bone Marrow Stromal Cells Induces NK Cell Triggering: Role of NKp30 and NKG2D Receptors
Authors: Poggi Alessandro , Prevosto Claudia , Massaro Anna-Maria , Negrini Simone , Urbani Serena , Pierri Ivana , Saccardi Riccardo , Gobbi Marco , Zocchi Maria Raffaella 
Published: April 2014

Abstract
In this study we have analyzed the interaction between in vitro cultured bone marrow stromal cells (BMSC) and NK cells. Ex vivo-isolated NK cells neoexpressed the activation Ag CD69 and released IFN-γ and TNF-α upon binding with BMSC. Production of these proinflammatory cytokines was dependent on ligation of ICAM1 expressed on BMSC and its receptor LFA1 on NK cells. Furthermore, the NKp30, among natural cytotoxicity receptors, appeared to be primarily involved in triggering NK cells upon interaction with BMSC. Unexpectedly, autologous IL-2-activated NK cells killed BMSC. Again, LFA1/ICAM1 interaction plays a key role in NK/BMSC interaction; this interaction is followed by a strong intracellular calcium increase in NK cells. More importantly, NKG2D/MHC-I-related stress-inducible molecule A and/or NKG2D/UL-16 binding protein 3 engagement is responsible for the delivery of a lethal hit. It appears that HLA-I molecules do not protect BMSC from NK cell-mediated injury. Thus, NK cells, activated upon binding with BMSC, may regulate BMSC survival.
Enhancement of HIV-Specific CD8 T Cell Responses by Dual Costimulation with CD80 and CD137L
Authors: Bukczynski Jacob , Wen Tao , Wang Chao , Christie Natasha , Routy Jean-Pierre , Boulassel Mohamed-Rachid , Kovacs Colin M. , MacDonald Kelly S. , Ostrowski Mario , Sekaly Rafick-Pierre , Bernard Nicole F. , Watts Tania H. 
Published: April 2014

Abstract
HIV-specific CD8 T cell responses are defective in chronic HIV infection. In this study, we report that costimulation with either CD137L (4-1BBL) or CD80 (B7.1) enhanced the Ag-specific expansion and acquisition of effector function by HIV-specific memory CD8 T cells. Ag-specific T cells from recently infected donors showed maximal expansion with single costimulatory molecules. Dual costimulation of T cells from recently infected donors or from healthy donors responding to influenza epitopes led to enhanced responses when the accumulation of cytokines was measured. However, accumulation of regulatory cytokines, particularly IFN-γ, led to inhibition of further Ag-specific CD8 T cell expansion in the cultures. This inhibition was relieved by neutralization of IFN-γ or of IFN-γ, TNF, and IL-10. Thus, strong costimulation of T cells in vitro can lead to induction of regulatory cytokines at levels that limit further T cell expansion. In marked contrast, T cells from long-term (&gt;4 years) infected HIV+ donors exhibited reduced Ag-specific CD8 T cell expansion, reduced CD4 T cell responses, and minimal cytokine accumulation. Dual costimulation with both 4-1BBL and B7.1 enhanced responses of T cells from long-term infected subjects to a level similar to that obtained with T cells from early in HIV infection. Experiments with purified CD8 T cells showed that B7.1 and 4-1BBL could act directly and synergistically on CD8 T cells. Taken together, these data suggest that 4-1BBL and B7.1 have additive or synergistic effects on HIV-specific CD8 T cell responses and represent a promising combination for therapeutic vaccination for HIV.
TLR-Dependent IL-4 Production by Invariant Vα14+Jα18+ NKT Cells to Initiate Contact Sensitivity In Vivo
Authors: Askenase Philip W. , Itakura Atsuko , Leite-de-Moraes Maria C. , Lisbonne Mariette , Roongapinun Sukit , Goldstein Daniel R. , Szczepanik Marian 
Published: April 2014

Abstract
LPS stimulated B-1 cell polyclonal in vivo IgM responses depend on IL-4 release by invariant Vα14+Jα18+ NKT (iNKT) cells. The IgM Abs can recruit effector T cells to mediate contact sensitivity. LPS activates the B-1 cell response just 1 day later, and depends on CD1d, iNKT cells, IL-4, TLR4, and MyD88. LPS in vivo and in vitro stimulates rapid preferential production of IL-4 in hepatic iNKT cells within 2 h. TLR4 were demonstrated in iNKT cells by flow cytometry and functional studies. Thus, innate microbial stimulation via TLR can activate iNKT cell and B-1 cell collaboration. The result is polyclonal IgM Ab responses capable of recruiting Ag-specific T cells into tissues. This may be involved in the promotion of autoimmunity by infectious agents.
Cyclin T1 Expression Is Regulated by Multiple Signaling Pathways and Mechanisms during Activation of Human Peripheral Blood Lymphocytes
Authors: Marshall Renée M. , Salerno Dominic , Garriga Judit , Graña Xavier 
Published: April 2014

Abstract
Stimulation of primary human T lymphocytes results in up-regulation of cyclin T1 expression, which correlates with phosphorylation of the C-terminal domain of RNA polymerase II (RNAP II). Up-regulation of cyclin T1 and concomitant stabilization of cyclin-dependent kinase 9 (CDK9) may facilitate productive replication of HIV in activated T cells. We report that treatment of PBLs with two mitogens, PHA and PMA, results in accumulation of cyclin T1 via distinct mechanisms. PHA induces accumulation of cyclin T1 mRNA and protein, which results from cyclin T1 mRNA stabilization, without significant change in cyclin T1 promoter activity. Cyclin T1 mRNA stabilization requires the activation of both calcineurin and JNK because inhibition of either precludes cyclin T1 accumulation. In contrast, PMA induces cyclin T1 protein up-regulation by stabilizing cyclin T1 protein, apparently independently of the proteasome and without accumulation of cyclin T1 mRNA. This process is dependent on Ca2+-independent protein kinase C activity but does not require ERK1/2 activation. We also found that PHA and anti-CD3 Abs induce the expression of both the cyclin/CDK complexes involved in RNAP II C-terminal domain phosphorylation and the G1-S cyclins controlling cell cycle progression. In contrast, PMA alone is a poor inducer of the expression of G1-S cyclins but often as potent as PHA in inducing RNAP II cyclin/CDK complexes. These findings suggest coordination in the expression and activation of RNAP II kinases by pathways that independently stimulate gene expression but are insufficient to induce S phase entry in primary T cells.
CD11chigh Dendritic Cell Ablation Impairs Lymphopenia-Driven Proliferation of Naive and Memory CD8+ T Cells
Authors: Zaft Tami , Sapoznikov Anita , Krauthgamer Rita , Littman Dan R. , Jung Steffen 
Published: April 2014

Abstract
The peripheral lymphocyte pool size is governed by homeostatic mechanisms. Thus, grafted T cells expand and replenish T cell compartments in lymphopenic hosts. Lymphopenia-driven proliferation of naive CD8+ T cells depends on self-peptide/MHC class I complexes and the cytokine IL-7. Lymphopenia-driven proliferation and maintenance of memory CD8+ T cells are MHC independent, but are believed to require IL-7 and contact with a bone marrow-derived cell that presents the cytokine IL-15 by virtue of its high affinity receptor (IL-15Rα). In this study we show that optimal spontaneous proliferation of grafted naive and memory CD8+ T cells in mice rendered lymphopenic through gene ablation or irradiation requires the presence of CD11chigh dendritic cells. Our results suggest a dual role of CD11chigh dendritic cells as unique APC and cytokine-presenting cells.
The Murine B Cell Repertoire Is Severely Selected against Endogenous Cellular Prion Protein
Authors: Grégoire Sylvie , Bergot Anne Sophie , Féraudet Cécile , Carnaud Claude , Aucouturier Pierre , Rosset Martine Bruley 
Published: April 2014

Abstract
Abs to the prion protein (PrP) can protect against experimental prion infections, but efficient Ab responses are difficult to generate because PrP is expressed on many tissues and induces a strong tolerance. We previously showed that immunization of wild-type mice with PrP peptides and CpG oligodeoxynucleic acid overcomes tolerance and induces cellular and humoral responses to PrP. In this study, we compared Ab and T cell repertoires directed to PrP in wild-type and PrP knockout (Prnpo/o) C57BL/6 mice. Animals were immunized with mouse PrP-plasmid DNA or with 30-mer overlapping peptides either emulsified in CFA or CpG/IFA. In Prnpo/o mice, Abs raised by PrP-plasmid DNA immunization recognized only N-terminal PrP peptides; analyses of Ab responses after PrP peptide/CFA immunization allowed us to identify six distinct epitopes, five of which were also recognized by Abs raised by PrP peptides/CpG. By contrast, in wild-type mice, no Ab response was detected after PrP-plasmid DNA or peptide/CFA immunization. However, when using CpG, four C-terminal peptides induced Abs specific for distinct epitopes. Importantly, immune sera from Prnpo/o but not from wild-type mice bound cell surface PrP. Abs of IgG1 and IgG2b subclasses predominated in Prnpo/o mice while the strongest signals were for IgG2b in wild-type mice. Most anti-PrP Th cells were directed to a single epitope in both Prnpo/o and wild-type mice. We conclude that endogenous PrPC expression profoundly affects the Ab repertoire as B cells reactive for epitopes exposed on native PrPC are strongly tolerized. Implications for immunotherapy against prion diseases are discussed.
Thymus-Dependent Memory Phenotype CD8 T Cells in Naive B6.H-2Kb−/−Db−/− Animals Mediate an Antigen-Specific Response against Listeria monocytogenes
Authors: Su Jie , Berg Rance E. , Murray Sean , Forman James 
Published: April 2014

Abstract
B6.H-2Kb−/−Db−/− (DKO) mice have greatly reduced numbers of mature CD8αβ T cells in their periphery. However, these non-class Ia-selected CD8αβ T cells are able to mediate immune responses to a number of pathogens. Approximately 60% of the CD8αβ T cells in the spleen and peripheral lymph nodes of naive DKO mice display a memory (CD44high) phenotype. To investigate the origins of these non-class Ia-selected CD8αβCD44high cells, we traced the phenotype of recent thymic emigrants and found that most were CD44low. We also determined whether their appearance was thymus dependent and found that only a small percentage of non-class Ia-selected CD8αβCD44high cells develop in a thymus-independent pathway. Functionally, CD8αβCD44high cells from DKO mice are able to secrete IFN-γ in response to IL-12 and IL-18 in the absence of cognate Ag. When challenged with anti-CD3 in vivo, nearly half of these cells produce IFN-γ within 3 h. When purified CD8αβCD44high cells from Thy1.2.DKO mice were transferred into Thy1.1 DKO recipients and then challenged with Listeria monocytogenes, an Ag-specific anti-L. monocytogenes response was observed 6 days later. Our data suggest that non-class Ia-selected CD8αβCD44high cells in naive animals can respond rapidly to Ag and play a role in the innate as well as the early phase of the acquired immune response.
CD73 and Ly-6A/E Distinguish In Vivo Primed but Uncommitted Mouse CD4 T Cells from Type 1 or Type 2 Effector Cells
Authors: Yang Li , Kobie James J. , Mosmann Tim R. 
Published: April 2014

Abstract
Primed CD4 T cells may develop into effector T cells such as Th1 and Th2, or remain uncommitted as Th primed precursor (Thpp) cells that can subsequently differentiate into Th1 and Th2 cells. Although mouse Thpp-like cells have also been identified among spleen and particularly lymph node cells, further characterization of these cells has been difficult without a defining cell surface marker. Using Affymetrix GeneChips followed by FACS analysis, we found that in vitro-derived Thpp cells expressed CD73 but not Ly-6A/E, whereas Th1 and Th2 cells showed the reciprocal pattern. CD73+ Ly6A/E− memory CD4 T cells were identified in normal C57BL/6 mice, and the proportion of these cells was highest in lymph nodes, lower in spleens, and lowest in the lungs. These cells produced IL-2 and MIP-1α, but much less IL-4 and IFN-γ than CD73− Ly6A/E+ cells. Similar results were obtained with additional Ly-6.2 mouse strains, but not Ly-6.1 strains. Restimulation of Thpp-like CD73+ Ly-6A/E− cells in Th1- or Th2-polarizing conditions induced differentiation into populations producing mainly IFN-γ or mainly IL-4, respectively. In contrast, the effector-like CD73− Ly-6A/E+ population was more committed, and continued to produce both IL-4 and IFN-γ in both conditions. CD73 and Ly-6A/E expression therefore identify a population of Thpp-like cells in C57BL/6 mice and at least some other Ly-6.2 mice.
Disruption of MHC Class II-Restricted Antigen Presentation by Vaccinia Virus
Authors: Li Ping , Wang Nan , Zhou Delu , Yee Christina S. K. , Chang Cheong-Hee , Brutkiewicz Randy R. , Blum Janice S. 
Published: April 2014

Abstract
Vaccinia virus (VV), currently used in humans as a live vaccine for smallpox, can interfere with host immunity via several discrete mechanisms. In this study, the effect of VV on MHC class II-mediated Ag presentation was investigated. Following VV infection, the ability of professional and nonprofessional APC to present Ag and peptides to CD4+ T cells was impaired. Viral inhibition of class II Ag presentation could be detected within 1 h, with diminished T cell responses dependent upon the duration of APC infection and virus titer. Exposure of APC to replication-deficient virus also diminished class II Ag presentation. Virus infection of APC perturbed Ag presentation by newly synthesized and recycling class II molecules, with disruptions in both exogenous and cytoplasmic Ag presentation. Virus-driven expression of an endogenous Ag, failed to restore T cell responsiveness specific for this Ag in the context of MHC class II molecules. Yet, both class II protein steady-state and cell surface expression were not altered by VV. Biochemical and functional analysis revealed that VV infection directly interfered with ligand binding to class II molecules. Together, these observations suggest that disruption of MHC class II-mediated Ag presentation may be one of multiple strategies VV has evolved to escape host immune surveillance.
Stepwise Differentiation of CD4 Memory T Cells Defined by Expression of CCR7 and CD27
Authors: Fritsch Ruth D. , Shen Xinglei , Sims Gary P. , Hathcock Karen S. , Hodes Richard J. , Lipsky Peter E. 
Published: April 2014

AbstractTo study the steps in the differentiation of human memory CD4 T cells, we characterized the functional and lineage relationships of three distinct memory CD4 subpopulations distinguished by their expression of the cysteine chemokine receptor CCR7 and the TNFR family member CD27. Using the combination of these phenotypic markers, three populations were defined: the CCR7+CD27+, the CCR7−CD27+, and the CCR7−CD27− population. In vitro stimulation led to a stepwise differentiation from naive to CCR7+CD27+ to CCR7−CD27+ to CCR7−CD27−. Telomere length in these subsets differed significantly (CCR7+CD27+ &gt; CCR7−CD27+ &gt; CCR7−CD27−), suggesting that these subsets constituted a differentiative pathway with progressive telomere shortening reflecting antecedent in vivo proliferation. The in vitro proliferative response of these populations declined, and their susceptibility to apoptosis increased progressively along this differentiation pathway. Cytokine secretion showed a differential functional capacity of these subsets. High production of IL-10 was only observed in CCR7+CD27+, whereas IFN-γ was produced by CCR7−CD27+ and to a slightly lesser extent by CCR7−CD27− T cells. IL-4 secretion was predominantly conducted by CCR7−CD27− memory CD4 T cells. Thus, by using both CCR7 and CD27, distinct maturational stages of CD4 memory T cells with different functional activities were defined.
The src Homology 2 Domain-Containing Tyrosine Phosphatase 2 Regulates Primary T-Dependent Immune Responses and Th Cell Differentiation
Authors: Salmond Robert J. , Huyer Gregory , Kotsoni Anastasia , Clements Lisa , Alexander Denis R. 
Published: April 2014

Abstract
The src homology 2 domain-containing tyrosine phosphatase 2 (SHP2) plays an important role in development and in growth factor receptor signaling pathways, yet little is known of its role in the immune system. We generated mice expressing a dominant-negative version of the protein, SHP2(CS), specifically in T cells. In SHP2(CS) mice, T cell development appears normal with regard to both negative and positive selection. However, SHP2(CS) T cells express higher levels of activation markers, and aged mice have elevated serum Abs. This is associated with a marked increase in IL-4, IL-5, and IL-10 secretion by SHP2(CS) T cells in vitro. In addition, primary thymus-dependent B cell responses are deficient in SHP2(CS) mice. We show that whereas TCR-induced linker for activation of T cells phosphorylation is defective, CTLA-4 and programmed death-1 signaling are not affected by SHP2(CS) expression. Our results suggest that a key action of wild-type SHP2 is to suppress differentiation of T cells to the Th2 phenotype.
Functional Analysis of HIV Type 1 Nef Reveals a Role for PAK2 as a Regulator of Cell Phenotype and Function in the Murine Dendritic Cell Line, DC2.4
Authors: Mann Jelena , Patrick Claire N. , Cragg Mark S. , Honeychurch Jamie , Mann Derek A. , Harris Mark 
Published: April 2014

Abstract
The HIV-1 Nef protein plays a critical role in viral pathogenesis. Nef has been shown to modulate dendritic cell (DC) function, in particular perturbing their ability to present Ag. To further characterize the effects of Nef on DCs, we established a panel of transfectants of the murine DC line, DC2.4, stably expressing differing levels of either wild-type Nef, or a number of Nef mutants lacking key functional motifs. Transfectants expressing increasing levels of wild-type Nef demonstrated a dose-dependent shrinkage and loss of dendrites. Nef expression levels also correlated with increased proliferative ability but did not confer resistance to proapoptotic stimuli. Importantly, Nef expression resulted in an impairment of Ag presentation to T cells correlating with a reduction in the cell surface expression of molecules involved in Ag presentation such as MHC class I, CD80/86, and ICAM-1. Nef expression also rendered DC2.4 cells resistant to the maturation stimulus provided by an anti-CD40 Ab. Mutations in either the myristoylation site or Src homology 3-domain binding polyproline motif of Nef abolished these effects. Previous studies had shown that these mutations also abolished the ability of Nef to activate the p21-activated kinase, PAK2. Consistent with this, stable expression of constitutively active PAK2 in DC2.4 mimicked the effects of Nef. We conclude that Nef, acting via activation of PAK2, inhibits both DC maturation and Ag presentation. These data have clear implications for the role of Nef in early stages of HIV-1 infection and validate Nef as a valid target for development of antiviral chemotherapeutics.
Differential Expression of IFN Regulatory Factor 4 Gene in Human Monocyte-Derived Dendritic Cells and Macrophages
Authors: Lehtonen Anne , Veckman Ville , Nikula Tuomas , Lahesmaa Riitta , Kinnunen Leena , Matikainen Sampsa , Julkunen Ilkka 
Published: April 2014

AbstractIn vitro human monocyte differentiation to macrophages or dendritic cells (DCs) is driven by GM-CSF or GM-CSF and IL-4, respectively. IFN regulatory factors (IRFs), especially IRF1 and IRF8, are known to play essential roles in the development and functions of macrophages and DCs. In the present study, we performed cDNA microarray and Northern blot analyses to characterize changes in gene expression of selected genes during cytokine-stimulated differentiation of human monocytes to macrophages or DCs. The results show that the expression of IRF4 mRNA, but not of other IRFs, was specifically up-regulated during DC differentiation. No differences in IRF4 promoter histone acetylation could be found between macrophages and DCs, suggesting that the gene locus was accessible for transcription in both cell types. Computer analysis of the human IRF4 promoter revealed several putative STAT and NF-κB binding sites, as well as an IRF/Ets binding site. These sites were found to be functional in transcription factor-binding and chromatin immunoprecipitation experiments. Interestingly, Stat4 and NF-κB p50 and p65 mRNAs were expressed at higher levels in DCs as compared with macrophages, and enhanced binding of these factors to their respective IRF4 promoter elements was found in DCs. IRF4, together with PU.1, was also found to bind to the IRF/Ets response element in the IRF4 promoter, suggesting that IRF4 protein provides a positive feedback signal for its own gene expression in DCs. Our results suggest that IRF4 is likely to play an important role in myeloid DC differentiation and gene regulatory functions.
Sphingosine Kinase 1 Is a Negative Regulator of CD4+ Th1 Cells
Authors: Yang Jianfei , Castle Brian E. , Hanidu Adedayo , Stevens Lisa , Yu Yang , Li Xiang , Stearns Carol , Papov Vladimir , Rajotte Daniel , Li Jun 
Published: April 2014

Abstract
CD4+ Th1 cells produce IFN-γ, TNF-α, and IL-2. These Th1 cytokines play critical roles in both protective immunity and inflammatory responses. In this study we report that sphingosine kinase 1 (SPHK1), but not SPHK2, is highly expressed in DO11.10 Th1 cells. The expression of SPHK1 in Th1 cells requires TCR signaling and new protein synthesis. SPHK1 phosphorylates sphingosine to form sphingosine-1-phosphate. Sphingosine-1-phosphate plays important roles in inhibition of apoptosis, promotion of cell proliferation, cell migration, calcium mobilization, and activation of ERK1/2. When SPHK1 expression was knocked down by SPHK1 short interfering RNA, the production of IL-2, TNF-α, and IFN-γ by Th1 cells in response to TCR stimulation was enhanced. Consistently, overexpression of dominant-negative SPHK1 increased the production of IL-2, TNF-α, and IFN-γ in Th1 cells. Furthermore, overexpression of SPHK1 in Th1 and Th0 cells decreased the expression of IL-2, TNF-α, and IFN-γ. Several chemokines, including Th2 chemokines CCL17 and CCL22, were up-regulated by SPHK1 short interfering RNA and down-regulated by overexpression of SPHK1. We also showed that Th2 cells themselves express CCL17 and CCL22. Finally, we conclude that SPHK1 negatively regulates the inflammatory responses of Th1 cells by inhibiting the production of proinflammatory cytokines and chemokines.