bluuebunny/crossref_metadata_2025_split huggingface dataset:
Actin and RIG-I/MAVS Signaling Components Translocate to Mitochondria upon Influenza A Virus Infection of Human Primary Macrophages
Authors: Öhman Tiina , Rintahaka Johanna , Kalkkinen Nisse , Matikainen Sampsa , Nyman Tuula A. 
Published: April 2009

Abstract
Influenza A virus is one of the most important causes of respiratory infection. During viral infection, multiple cell signaling cascades are activated, resulting in the production of antiviral cytokines and initiation of programmed cell death of virus-infected cells. In the present study, we have used subcellular proteomics to reveal the host response to influenza A infection at the protein level in human macrophages. Macrophages were infected with influenza A virus, after which the cytosolic and mitochondrial cell fractions were prepared and analyzed by using two-dimensional electrophoresis for protein separation and mass spectrometry for protein identification. In cytosolic proteomes, the level of several heat shock proteins and fragments of cytoskeletal proteins was clearly up-regulated during influenza A virus infection. In mitochondrial proteomes, simultaneously with the expression of viral proteins, the level of intact actin and tubulin was highly up-regulated. This was followed by translocation of the components of antiviral RNA recognition machinery, including RIG-I (retinoic acid-inducible protein I), TRADD (TNFR1-associated death domain protein), TRIM25 (tripartite motif protein 25), and IKKε (inducible IκB kinase), onto the mitochondria. Cytochalasin D, a potent inhibitor of actin polymerization, clearly inhibited influenza A virus-induced expression of IFN-β, IL-29, and TNF-α, suggesting that intact actin cytoskeleton structure is crucial for proper activation of antiviral response. At late phases of infection mitochondrial fragmentation of actin was seen, indicating that actin fragments, fractins, are involved in disruption of mitochondrial membranes during apoptosis of virus-infected cells. In conclusion, our results suggest that actin network interacts with mitochondria to regulate both antiviral and cell death signals during influenza A virus infection.
Pertussis Toxin Signals through the TCR to Initiate Cross-Desensitization of the Chemokine Receptor CXCR4
Authors: Schneider Olivia D. , Weiss Alison A. , Miller William E. 
Published: April 2009

Abstract
Pertussis toxin (PTx) has been shown to exert a variety of effects on immune cells independent of its ability to ADP-ribosylate G proteins. Of these effects, the binding subunit of PTx (PTxB) has been shown to block signaling via the chemokine receptor CCR5, but the mechanism involved in this process is unknown. Here, we show that PTxB causes desensitization of a related chemokine receptor, CXCR4, and explore the mechanism by which this occurs. CXCR4 is the receptor for the chemokine stromal cell-derived factor 1α (SDF-1α) and elicits a number of biological effects, including stimulation of T cell migration. PTxB treatment causes a decrease in CXCR4 surface expression, inhibits G protein-associated signaling, and blocks SDF-1α-mediated chemotaxis. We show that PTxB mediates these effects by activating the TCR signaling network, as the effects are dependent on TCR and ZAP70 expression. Additionally, the activation of the TCR with anti-CD3 mAb elicits a similar set of effects on CXCR4 activity, supporting the idea that TCR signaling leads to cross-desensitization of CXCR4. The inhibition of CXCR4 by PTxB is rapid and transient; however, the catalytic activity of PTx prevents CXCR4 signaling in the long term. Thus, the effects of PTx holotoxin on CXCR4 signaling can be divided into two phases: short term by the B subunit, and long term by the catalytic subunit. These data suggest that TCR crosstalk with CXCR4 is likely a normal cellular process that leads to cross-desensitization, which is exploited by the B subunit of PTx.
Cutting Edge: Regulatory T Cells Do Not Require Stimulation through Their TCR to Suppress
Authors: Szymczak-Workman Andrea L. , Workman Creg J. , Vignali Dario A. A. 
Published: April 2009

Abstract
The mechanism and stimulatory requirements of regulatory T cell (Treg)-mediated suppression are still unclear. To assess the requirement for Treg stimulation by cognate peptide:MHC, we used T cells from OTII and AND TCR transgenic mice that are specific for and restricted by distinct, noncrossreactive peptide:MHC combinations. This allowed us to independently activate Tregs and their conventional T cell (Tconv) targets. Surprisingly, we found that suppression can occur in the absence of peptide:MHC-mediated stimulation of Tregs. This suppression was Treg dependent and not due to cold target inhibition. Using Rag1−/− TCR transgenic T cells, we show that regulation of Tconv proliferation by heterogeneous Tregs is not due to alloreactivity or crossreactivity. Finally, using anti-TCR-Vβ8-coated microbeads and Vβ8− Tregs, we show that TCR stimulation-independent suppression can occur in the absence of APCs. These data suggest that Tregs may possess constitutive regulatory activity that can be mediated in the absence of cognate peptide:MHC-TCR stimulation.
The Essential Role of LAT in Thymocyte Development during Transition from the Double-Positive to Single-Positive Stage
Authors: Shen Shudan , Zhu Minghua , Lau Jasmine , Chuck Mariana , Zhang Weiguo 
Published: April 2009

AbstractThe linker for activation of T cells (LAT) is an adaptor protein that couples TCR engagement to downstream signaling cascades. LAT is important in early thymocyte development as LAT-deficient mice have a complete block at the double-negative (DN) 3 stage. To study the role of LAT beyond the DN3 stage, we generated mice in which the lat gene could be deleted by the Cre recombinase. Analysis of these mice showed that deletion of LAT after the DN3 stage allowed thymocytes to develop past the DN3 to DN4 checkpoint and to generate double-positive thymocytes. However, LAT-deficient DP thymocytes were severely defective in responding to stimulation via the TCR and failed to differentiate into single-positive thymocytes efficiently. Consequently, few LAT-deficient mature T cells could be found in the periphery. These T cells had undergone extensive homeostatic proliferation and expressed low levels of the TCR on their surface. Collectively, our data indicate that in addition to its role in pre-TCR signaling, LAT also plays an essential role in thymocyte development during transition from the double-positive to single-positive stage.
Human Chorionic Gonadotropin Attracts Regulatory T Cells into the Fetal-Maternal Interface during Early Human Pregnancy
Authors: Schumacher Anne , Brachwitz Nadja , Sohr Sindy , Engeland Kurt , Langwisch Stefanie , Dolaptchieva Maria , Alexander Tobias , Taran Andrei , Malfertheiner Sara Fill , Costa Serban-Dan , Zimmermann Gerolf , Nitschke Cindy , Volk Hans-Dieter , Alexander Henry , Gunzer Matthias , Zenclussen Ana Claudia 
Published: April 2009

Abstract
Regulatory T cells (Treg) expand during pregnancy and are present at the fetal-maternal interface at very early stages in pregnancy. The migration mechanisms of Treg to the pregnant uterus are still unclear. Human chorionic gonadotropin (hCG) is secreted by the blastocyst immediately after fertilization and has chemoattractant properties. Therefore, we sought to analyze whether hCG secreted by early trophoblasts attracts Treg to the uterus and hence contributes to maternal tolerance toward the fetus. Decidua and placenta tissue samples from patients having spontaneous abortions or ectopic pregnancies were employed to evaluate Treg and hCG levels. Age-matched samples from normal pregnant women served as controls. We further performed in vitro studies with primary first trimester trophoblast cells and a choriocarcinoma cell line (JEG-3) aiming to evaluate the ability of secreted hCG to attract Treg. Patients having miscarriages or ectopic pregnancy presented significantly decreased hCG mRNA and protein levels associated with decreased Foxp3, neuropilin-1, IL-10, and TGF-β mRNA levels as compared with normal pregnant women. Using migration assays we demonstrated that Treg were attracted by hCG-producing trophoblasts or choriocarcinoma cells. Treg migration toward cells transfected with hCG expression vectors confirmed the chemoattractant ability of hCG. Our data clearly show that hCG produced by trophoblasts attracts Treg to the fetal-maternal interface. High hCG levels at very early pregnancy stages ensure Treg to migrate to the site of contact between paternal Ags and maternal immune cells and to orchestrate immune tolerance toward the fetus.
PD-1 Is a Regulator of NY-ESO-1-Specific CD8+ T Cell Expansion in Melanoma Patients
Authors: Fourcade Julien , Kudela Pavol , Sun Zhaojun , Shen Hongmei , Land Stephanie R. , Lenzner Diana , Guillaume Philippe , Luescher Immanuel F. , Sander Cindy , Ferrone Soldano , Kirkwood John M. , Zarour Hassane M. 
Published: April 2009

Abstract
The programmed death 1 (PD-1) receptor is a negative regulator of activated T cells and is up-regulated on exhausted virus-specific CD8+ T cells in chronically infected mice and humans. Programmed death ligand 1 (PD-L1) is expressed by multiple tumors, and its interaction with PD-1 resulted in tumor escape in experimental models. To investigate the role of PD-1 in impairing spontaneous tumor Ag-specific CD8+ T cells in melanoma patients, we have examined the effect of PD-1 expression on ex vivo detectable CD8+ T cells specific to the tumor Ag NY-ESO-1. In contrast to EBV, influenza, or Melan-A/MART-1-specific CD8+ T cells, NY-ESO-1-specific CD8+ T cells up-regulated PD-1 expression. PD-1 up-regulation on spontaneous NY-ESO-1-specific CD8+ T cells occurs along with T cell activation and is not directly associated with an inability to produce cytokines. Importantly, blockade of the PD-1/PD-L1 pathway in combination with prolonged Ag stimulation with PD-L1+ APCs or melanoma cells augmented the number of cytokine-producing, proliferating, and total NY-ESO-1-specific CD8+ T cells. Collectively, our findings support the role of PD-1 as a regulator of NY-ESO-1-specific CD8+ T cell expansion in the context of chronic Ag stimulation. They further support the use of PD-1/PD-L1 pathway blockade in cancer patients to partially restore NY-ESO-1-specific CD8+ T cell numbers and functions, increasing the likelihood of tumor regression.
Impaired CD4 and CD8 Effector Function and Decreased Memory T Cell Populations in ICOS-Deficient Patients
Authors: Takahashi Naomi , Matsumoto Kenji , Saito Hirohisa , Nanki Toshihiro , Miyasaka Nobuyuki , Kobata Tetsuji , Azuma Miyuki , Lee Sang-Kyou , Mizutani Shuki , Morio Tomohiro 
Published: April 2009

Abstract
Interaction of ICOS with its ligand is essential for germinal center formation, T cell immune responses, and development of autoimmune diseases. Human ICOS deficiency has been identified worldwide in nine patients with identical ICOS mutations. In vitro studies of the patients to date have shown only mild T cell defect. In this study, we report an in-depth analysis of T cell function in two siblings with novel ICOS deficiency. The brother displayed mild skin infections and impaired Ig class switching, whereas the sister had more severe symptoms, including immunodeficiency, rheumatoid arthritis, inflammatory bowel disease, interstitial pneumonitis, and psoriasis. Despite normal CD3/CD28-induced proliferation and IL-2 production in vitro, peripheral blood T cells in both patients showed a decreased percentage of CD4 central and effector memory T cells and impaired production of Th1, Th2, and Th17 cytokines upon CD3/CD28 costimulation or PMA/ionophore stimulation. The defective polarization into effector cells was associated with impaired induction of T-bet, GATA3, MAF, and retinoic acid-related orphan nuclear hormone receptor (RORC). Reduced CTLA-4+CD45RO+FoxP3+ regulatory T cells and diminished induction of inhibitory cell surface molecules, including CTLA-4, were also observed in the patients. T cell defect was not restricted to CD4 T cells because reduced memory T cells and impaired IFN-γ production were also noted in CD8 T cells. Further analysis of the patients demonstrated increased induction of receptor activator of NF-κB ligand (RANKL), lack of IFN-γ response, and loss of Itch expression upon activation in the female patient, who had autoimmunity. Our study suggests that extensive T cell dysfunction, decreased memory T cell compartment, and imbalance between effector and regulatory cells in ICOS-deficient patients may underlie their immunodeficiency and/or autoimmunity.
Assembled DJβ Complexes Influence TCRβ Chain Selection and Peripheral Vβ Repertoire
Authors: Carpenter Andrea C. , Yang-Iott Katherine S. , Chao Linda H. , Nuskey Beth , Whitlow Scott , Alt Frederick W. , Bassing Craig H. 
Published: April 2009

Abstract
TCRβ chain repertoire of peripheral αβ T cells is generated through the stepwise assembly and subsequent selection of TCRβ V region exons during thymocyte development. To evaluate the influence of a two-step recombination process on Vβ rearrangement and selection, we generated mice with a preassembled Dβ1Jβ1.1 complex on the Jβ1ω allele, an endogenous TCRβ allele that lacks the Dβ2-Jβ2 cluster, creating the Jβ1DJβ allele. As compared with Jβ1ω/ω mice, both Jβ1DJβ/ω and Jβ1DJβ/DJβ mice exhibited grossly normal thymocyte development and TCRβ allelic exclusion. In addition, Vβ rearrangements on Jβ1DJβ and Jβ1ω alleles were similarly regulated by TCRβ-mediated feedback regulation. However, in-frame VβDJβ rearrangements were present at a higher level on the Jβ1DJβ alleles of Jβ1DJβ/ω αβ T cell hybridomas, as compared with on the Jβ1ω alleles. This bias was most likely due to both an increased frequency of Vβ-to-DJβ rearrangements on Jβ1DJβ alleles and a preferential selection of cells with in-frame VβDJβ exons assembled on Jβ1DJβ alleles during the development of Jβ1DJβ/ω αβ T cells. Consistent with the differential selection of in-frame VβDJβ rearrangements on Jβ1DJβ alleles, the Vβ repertoire of αβ T cells was significantly altered during αβ TCR selection in Jβ1DJβ/ω and Jβ1DJβ/DJβ mice, as compared with in Jβ1ω/ω mice. Our data indicate that the diversity of DJβ complexes assembled during thymocyte development influences TCRβ chain selection and peripheral Vβ repertoire.
IL-7 Receptor Expression Provides the Potential for Long-Term Survival of Both CD62Lhigh Central Memory T Cells and Th1 Effector Cells during Leishmania major Infection
Authors: Colpitts Sara L. , Dalton Nicole M. , Scott Phillip 
Published: April 2009

Abstract
Infection with the intracellular protozoan parasite Leishmania major induces a state of concomitant immunity wherein secondary immunity is dependent upon the persistence of the original pathogen. Our laboratory has described two populations of Leishmania-induced CD4+ T cells that contribute to immunity: CD62Lhigh central memory T (TCM) cells and CD62Llow effector T cells. To determine whether the prosurvival cytokine IL-7 contributes to maintaining these T cells, we examined expression of the IL7R on CD4+ T cells activated during L. major infection. We found that TCM cells present in chronically infected mice expressed high levels of the IL7R. However, in addition to the expression of the IL7R by TCM cells, CD62Llow cells responding to L. major infection expressed the IL7R. Additional experiments revealed that a large percentage of the IL7RhighCD62Llow cells were Th1 cells, based on transcription at the IFN-γ locus and up-regulation of the Th1-promoting transcription factor T-bet. The up-regulation of T-bet did not prevent IL7R expression by L. major-responding CD4+ T cells, nor did the absence of T-bet result in increased IL7R expression. Finally, blockade of IL7R signaling decreased the number of T-bet+CD4+ T cells, reduced IFN-γ production, and inhibited delayed-type hypersensitivity responses in immune mice challenged with L. major, indicating that IL7R signaling contributes to the maintenance of Th1 effector cells. Thus, both TCM and Th1 effector cells can express the IL7R during chronic L. major infection, which provides a potential means for their long-term survival in addition to the presence of persisting parasites.
Impact of Intrinsic Cooperative Thermodynamics of Peptide-MHC Complexes on Antiviral Activity of HIV-Specific CTL
Authors: Motozono Chihiro , Yanaka Saeko , Tsumoto Kouhei , Takiguchi Masafumi , Ueno Takamasa 
Published: April 2009

Abstract
The antiviral activity of HIV-specific CTL is not equally potent but rather is dependent on their specificity. But what characteristic of targeted peptides influences CTL antiviral activity remains elusive. We addressed this issue based on HLA-B35-restricted CTLs specific for two overlapping immunodominant Nef epitopes, VY8 (VPLRPMTY) and RY11 (RPQVPLRPMTY). VY8-specific CTLs were more potently cytotoxic toward HIV-infected primary CD4+ cells than RY11-specific CTLs. Reconstruction of their TCR revealed no substantial difference in their functional avidity toward cognate Ags. Instead, the decay analysis of the peptide-MHC complex (pMHC) revealed that the VY8/HLA-B35 complex could maintain its capacity to sensitize T cells much longer than its RY11 counterpart. Corroboratively, the introduction of a mutation in the epitopes that substantially delayed pMHC decay rendered Nef-expressing target cells more susceptible to CTL killing. Moreover, by using differential scanning calorimetry and circular dichroism analyses, we found that the susceptible pMHC ligands for CTL killing showed interdependent and cooperative, rather than separate or sequential, transitions within their heterotrimer components under the thermally induced unfolding process. Collectively, our results highlight the significant effects of intrinsic peptide factors that support cooperative thermodynamics within pMHC on the efficient CTL killing of HIV-infected cells, thus providing us better insight into vaccine design.
Deletion of PPARγ in Alveolar Macrophages Is Associated with a Th-1 Pulmonary Inflammatory Response
Authors: Malur Anagha , Mccoy Almedia J. , Arce Sergio , Barna Barbara P. , Kavuru Mani S. , Malur Achut G. , Thomassen Mary Jane 
Published: April 2009

Abstract
Peroxisome proliferator-activated receptor γ (PPARγ) is constitutively expressed at high levels in healthy alveolar macrophages, in contrast to other tissue macrophages and blood monocytes. PPARγ ligands have been shown to down-regulate IFN-γ-stimulated inducible NO synthase (iNOS) in macrophages. Because NO is an important inflammatory mediator in the lung, we hypothesized that deletion of alveolar macrophage PPARγ in vivo would result in up-regulation of iNOS and other inflammatory mediators. The loss of PPARγ in macrophages was achieved by crossing floxed (+/+) PPARγ mice and a transgenic mouse containing the CRE recombinase gene under the control of the murine M lysozyme promoter (PPARγKO). Alveolar macrophages were harvested by bronchoalveolar lavage (BAL). Lymphocytes (CD8:CD4 ratio = 2.8) were increased in BAL of PPARγKO vs wild-type C57BL6; p ≤ 0.0001. Both iNOS and IFN-γ expression were significantly elevated (p ≤ 0.05) in BAL cells. Th-1 associated cytokines including IL-12 (p40), MIP-1α (CCL3), and IFN inducible protein-10 (IP-10, CXCL10) were also elevated. IL-4 and IL-17A were not detected. To test whether these alterations were due to the lack of PPARγ, PPARγ KO mice were intratracheally inoculated with a PPARγ lentivirus construct. PPARγ transduction resulted in significantly decreased iNOS and IFN-γ mRNA expression, as well as reduced BAL lymphocytes. These results suggest that lack of PPARγ in alveolar macrophages disrupts lung homeostasis and results in a Th1-like inflammatory response.
Target-Dependent B7-H1 Regulation Contributes to Clearance of Central Nervous Sysyem Infection and Dampens Morbidity
Authors: Phares Timothy W. , Ramakrishna Chandran , Parra Gabriel I. , Epstein Alan , Chen Lieping , Atkinson Roscoe , Stohlman Stephen A. , Bergmann Cornelia C. 
Published: April 2009

Abstract
The neurotropic coronavirus JHM strain of mouse hepatitis virus persists in oligodendroglia despite the presence of virus-specific CD8 T cells. Expression of programmed death 1 (PD-1) and B7-H1 were studied during acute and persistent infection to examine whether this negative regulatory mechanism contributes to CNS viral persistence. The majority of CNS-infiltrating CD8 T cells expressed PD-1, with the highest levels on virus-specific CD8 T cells. Moreover, despite control of infectious virus, CD8 T cells within the CNS of persistently infected mice maintained high PD-1 expression. Analysis of virus-susceptible target cells in vivo revealed that B7-H1 expression was regulated in a cell type-dependent manner. Oligodendroglia and microglia up-regulated B7-H1 following infection; however, although B7-H1 expression on oligodendroglia was prominent and sustained, it was significantly reduced and transient on microglia. Infection of mice deficient in the IFN-γ or IFN-α/β receptor demonstrated that B7-H1 expression on oligodendroglia is predominantly regulated by IFN-γ. Ab blockade of B7-H1 on oligodendroglia in vitro enhanced IFN-γ secretion by virus-specific CD8 T cells. More efficient virus control within the CNS of B7-H1-deficient mice confirmed inhibition of CD8 T cell function in vivo. Nevertheless, the absence of B7-H1 significantly increased morbidity without altering demyelination. These data are the first to demonstrate glia cell type-dependent B7-H1 regulation in vivo, resulting in adverse effects on antiviral CD8 T cell function. However, the beneficial role of PD-1:B7-H1 interactions in limiting morbidity highlights the need to evaluate tissue-specific intervention strategies.
Lipopolysaccharide Potentiates Effector T Cell Accumulation into Nonlymphoid Tissues through TRIF
Authors: McAleer Jeremy P. , Rossi Robert J. , Vella Anthony T. 
Published: April 2009

AbstractLPS is a natural adjuvant that potentiates Ag-specific T cell survival and Th1 differentiation by stimulating MyD88 and Toll/IL-1R domain-containing adaptor-inducing IFN-β (TRIF) signaling pathways. In this study, we reveal the TRIF pathway is critical for amplifying murine effector T cell accumulation into nonlymphoid tissues following immunization with Ag plus LPS. Although LPS increased the accumulation of splenic T cells in TRIF-deficient mice, markedly fewer T cells were recovered from liver and lung in comparison to wild type. Most of the T cells primed in TRIF-deficient mice failed to up-regulate CXCR3 and had an overall reduced capacity to produce IFN-γ, demonstrating effector T cell differentiation was linked to their migration. To investigate the role of TRIF-dependent cytokines, neutralization studies were performed in wild type mice. Although TNF neutralization reduced T cell numbers, its coneutralization with IL-10 unexpectedly restored the T cells, suggesting the balance between pro- and anti-inflammatory cytokines influences T cell survival rather than their magnitude. To investigate a role for costimulatory molecules, we tested whether the T cell defect in TRIF-deficient mice could be corrected with enforced costimulation. Boosting with a CD40 agonist in addition to LPS restored the effector CD8 T cell response in livers of TRIF-deficient mice while only partially restoring CD4 T cells, suggesting that LPS primes CD8 and CD4 T cell immunity through different mechanisms. Overall, our data support targeting TRIF for vaccines aimed to direct immune responses to nonlymphoid tissues.