bluuebunny/crossref_metadata_2025_split huggingface dataset:
Immunomodulatory Mediators from Pollen Enhance the Migratory Capacity of Dendritic Cells and License Them for Th2 Attraction
Authors: Mariani Valentina , Gilles Stefanie , Jakob Thilo , Thiel Martina , Mueller Martin J. , Ring Johannes , Behrendt Heidrun , Traidl-Hoffmann Claudia 
Published: April 2014

Abstract
The immune response of atopic individuals against allergens is characterized by increased levels of Th2 cytokines and chemokines. However, the way in which the cytokine/chemokine profile is matched to the type of invading allergen, and why these profiles sometimes derail and lead to disease, is not well understood. We recently demonstrated that pollen modulates dendritic cell (DC) function in a way that results in an enhanced capacity to initiate Th2 responses in vitro. Here, we examined the effects of aqueous birch pollen extracts (Bet.-APE) on chemokine receptor expression and chemokine production by human monocyte-derived DCs. Bet.-APE strongly induced expression and function of CXCR4 and reduced CCR1 and CCR5 expression on immature DCs. In addition, DC treatment with Bet.-APE significantly reduced LPS-induced production of CXCL10/IP-10, CCL5/RANTES; induced CCL22/macrophage-derived chemokine; and did not significantly change release of CCL17/thymus and activation-regulated chemokine. At a functional level, Bet.-APE increased the capacity of LPS-stimulated DCs to attract Th2 cells, whereas the capacity to recruit Th1 cells was reduced. Bet.-APE significantly and dose-dependently enhanced intracellular cAMP, suggesting that water-soluble factors from pollen grains bind a Gαs-protein-coupled receptor. E1-Phytoprostanes were identified to be one player in the Th2-polarizing potential of aqueous pollen extracts. In summary, our results demonstrate that pollen itself releases regulatory mediators which generate a Th2-promoting micromilieu with preferential recruitment of Th2 cells to the site of pollen exposure.
IL-21 Promotes Differentiation of Naive CD8 T Cells to a Unique Effector Phenotype
Authors: Casey Kerry A. , Mescher Matthew F. 
Published: April 2014

Abstract
IL-21, the most recently described member of the common γ-chain cytokine family, is produced by activated CD4 T cells, whereas CD8 T cells express the IL-21 receptor. To investigate a possible role for IL-21 in the priming of naive CD8 T cells, we examined responses of highly purified naive OT-I CD8 T cells to artificial APCs displaying Ag and B7-1 on their surface. We found that IL-21 enhanced OT-I clonal expansion and supported development of cytotoxic effector function. High levels of IL-2 did not support development of effector functions, but IL-2 was required for optimal responses in the presence of IL-21. IL-12 and IFN-α have previously been shown to support naive CD8 T cell differentiation and acquisition of effector functions through a STAT4-dependent mechanism. Here, we show that IL-21 does not require STAT4 to stimulate development of cytolytic activity. Furthermore, IL-21 fails to induce IFN-γ or IL-4 production and can partially block IL-12 induction of IFN-γ production. CD8 T cells that differentiate in response to IL-21 have a distinct surface marker expression pattern and are characterized as CD44high, PD-1low, CD25low, CD134low, and CD137low. Thus, IL-21 can provide a signal required by naive CD8 T cells to differentiate in response to Ag and costimulation, and the resulting effector cells represent a unique effector phenotype with highly effective cytolytic activity, but deficient capacity to secrete IFN-γ.
Single-Stranded RNA Derived from HIV-1 Serves as a Potent Activator of NK Cells
Authors: Alter Galit , Suscovich Todd J. , Teigen Nickolas , Meier Angela , Streeck Hendrik , Brander Christian , Altfeld Marcus 
Published: April 2014

Abstract
Persistent immune activation is a hallmark of chronic viremic HIV-1 infection. Activation of cells of the innate immune system, such as NK cells, occurs rapidly upon infection, and is sustained throughout the course of the disease. However, the precise underlying mechanism accounting for the persistent HIV-1-induced activation of NK cells is poorly understood. In this study, we assessed the role of uridine-rich ssRNA derived from the HIV-1 long terminal repeat (ssRNA40) on activation of NK cells via TLR7/8. Although dramatic activation of NK cells was observed following stimulation of PBMC with ssRNA40, negligible activation was observed following stimulation of purified NK cells despite their expression of TLR8 mRNA and protein. The functional activation of NK cells by this HIV-1-encoded TLR7/8 ligand could not be reconstituted with exogenous IL-12, IFN-α, or TNF-α, but was critically dependent on the direct contact of NK cells with plasmacytoid dendritic cells or CD14+ monocytes, indicating an important level of NK cell cross-talk and regulation by accessory cells during TLR-mediated activation. Coincubation of monocyte/plasmacytoid dendritic cells, NK cells, and ssRNA40 potentiated NK cell IFN-γ secretion in response to MHC-devoid target cells. Studies using NK cells derived from individuals with chronic HIV-1 infection demonstrated a reduction of NK cell responsiveness following stimulation with TLR ligands in viremic HIV-1 infection. These data demonstrate that HIV-1-derived TLR ligands can contribute to the immune activation of NK cells and may play an important role in HIV-1-associated immunopathogenesis and NK cell dysfunction observed during acute and chronic viremic HIV-1 infection.
OX40-Mediated Differentiation to Effector Function Requires IL-2 Receptor Signaling but Not CD28, CD40, IL-12Rβ2, or T-bet
Authors: Williams Cortny A. , Murray Susan E. , Weinberg Andrew D. , Parker David C. 
Published: April 2014

Abstract
Ag-specific CD4 T cells transferred into unirradiated Ag-bearing recipients proliferate, but survival and accumulation of proliferating cells is not extensive and the donor cells do not acquire effector functions. We previously showed that a single costimulatory signal delivered by an agonist Ab to OX40 (CD134) promotes accumulation of proliferating cells and promotes differentiation to effector CD4 T cells capable of secreting IFN-γ. In this study, we determined whether OX40 costimulation requires supporting costimulatory or differentiation signals to drive acquisition of effector T cell function. We report that OX40 engagement drives effector T cell differentiation in the absence of CD28 and CD40 signals. Two important regulators of Th1 differentiation, IL-12R and T-bet, also are not required for acquisition of effector function in CD4 T cells responsive to OX40 stimulation. Finally, we show that CD25-deficient CD4 T cells produce little IFN-γ in the presence of OX40 costimulation compared with wild type, suggesting that IL-2R signaling is required for efficient OX40-mediated differentiation to IFN-γ secretion.
Tumor-Reactive CD4+ T Cell Responses to the Melanoma-Associated Chondroitin Sulphate Proteoglycan in Melanoma Patients and Healthy Individuals in the Absence of Autoimmunity
Authors: Erfurt Cornelia , Sun Zhaojun , Haendle Ina , Schuler-Thurner Beatrice , Heirman Carlo , Thielemans Kris , van der Bruggen Pierre , Schuler Gerold , Schultz Erwin S. 
Published: April 2014

Abstract
To avoid immune escape by down-regulation or loss of Ag by the tumor cells, target Ags are needed, which are important for the malignant phenotype and survival of the tumor. We could identify a CD4+ T cell epitope derived from the human melanoma-associated chondroitin sulfate proteoglycan (MCSP) (also known as high m.w.-melanoma-associated Ag), which is strongly expressed on &gt;90% of human melanoma lesions and is important for the motility and invasion of melanoma cells. However, MCSP is not strictly tumor specific, because it is also expressed in a variety of normal tissues. Therefore, self tolerance should prevent the induction of strong T cell responses against these Ags by vaccination strategies. In contrast, breaking self tolerance to this Ag by effectively manipulating the immune system might mediate antitumor responses, although it would bear the risk of autoimmunity. Surprisingly, we could readily isolate CD4+ Th cells from the blood of a healthy donor-recognizing peptide MCSP693–709 on HLA-DR11-expressing melanoma cells. Broad T cell reactivity against this Ag could be detected in the peripheral blood of both healthy donors and melanoma patients, without any apparent signs of autoimmune disease. In some patients, a decline of T cell reactivity was observed upon tumor progression. Our data indicate that CD4+ T cells are capable of recognizing a membrane glycoprotein that is important in melanoma cell function, and it may be possible that the sizable reactivity to this Ag in most normal individuals contributes to immune surveillance against cancer.
CD4+ T Cells from Simian Immunodeficiency Virus Disease-Resistant Sooty Mangabeys Produce More IL-2 Than Cells from Disease-Susceptible Species: Involvement of p300 and CREB at the Proximal IL-2 Promoter in IL-2 Up-Regulation
Authors: Bostik Pavel , Noble Erika S. , Stephenson Susan T. , Villinger Francois , Ansari Aftab A. 
Published: April 2014

Abstract
IL-2 is an important cytokine required for the physiological function of CD4+ T cells. Immunological unresponsiveness—anergy— of CD4+ T cells is characterized by the inability of these cells to synthesize IL-2. Both progressive HIV infection leading to AIDS in humans and SIV infection in rhesus macaques (RM) are associated with dysregulation of IL-2 synthesis. In certain nonhuman primate species, such as sooty mangabeys (SM), SIV infection does not lead to AIDS. We have shown that this is associated with the resistance of the CD4+ T cells from SM to undergo anergy in vitro. In this study, we show that CD4+ T cells from SM spontaneously synthesize 2- to 3-fold higher levels of IL-2 than corresponding cells from RM. Proximal IL-2 promoter constructs derived from SM show significantly higher activity than the RM-derived constructs in primary CD4+ T cells, which is associated with an element at approximately nt −200. Activity of both constructs was up-regulated by p300 and down-regulated by CREB to a similar degree. Chromatin immunoprecipitation analysis showed significantly higher binding of p300 and lower binding of CREB to the SM promoter in vivo. Two single nucleotide substitutions present in the SM sequence around position −200 and −180 seem to increase the affinity of these sites for the binding of transcription factors, one of which was identified as Oct-1. These unique characteristics of the proximal IL-2 promoter in SM therefore can represent one of the mechanisms contributing to the resistance of these cells to undergo anergy.
Availability of a Diversely Avid CD8+ T Cell Repertoire Specific for the Subdominant HLA-A2-Restricted HIV-1 Gag p2419–27 Epitope
Authors: Schaubert Keri L. , Price David A. , Frahm Nicole , Li Jinzhu , Ng Hwee L. , Joseph Aviva , Paul Elyse , Majumder Biswanath , Ayyavoo Velpandi , Gostick Emma , Adams Sharon , Marincola Francesco M. , Sewell Andrew K. , Altfeld Marcus , Brenchley Jason M. , Douek Daniel C. , Yang Otto O. , Brander Christian , Goldstein Harris , Kan-Mitchell June 
Published: April 2014

Abstract
HLA-A2-restricted CTL responses to immunodominant HIV-1 epitopes do not appear to be very effective in the control of viral replication in vivo. In this study, we studied human CD8+ T cell responses to the subdominant HLA-A2-restricted epitope TV9 (Gag p2419–27, TLNAWVKVV) to explore the possibility of increasing its immune recognition. We confirmed in a cohort of 313 patients, infected by clade B or clade C viruses, that TV9 is rarely recognized. Of interest, the functional sensitivity of the TV9 response can be relatively high. The potential T cell repertoires for TV9 and the characteristics of constituent clonotypes were assessed by ex vivo priming of circulating CD8+ T cells from healthy seronegative donors. TV9-specific CTLs capable of suppressing viral replication in vitro were readily generated, suggesting that the cognate T cell repertoire is not limiting. However, these cultures contained multiple discrete populations with a range of binding avidities for the TV9 tetramer and correspondingly distinct functional dependencies on the CD8 coreceptor. The lack of dominant clonotypes was not affected by the stage of maturation of the priming dendritic cells. Cultures primed by dendritic cells transduced to present endogenous TV9 were also incapable of clonal maturation. Thus, a diffuse TCR repertoire appeared to be an intrinsic characteristic of TV9-specific responses. These data indicate that subdominance is not a function of poor immunogenicity, cognate TCR repertoire availability, or the potential avidity properties thereof, but rather suggest that useful responses to this epitope are suppressed by competing CD8+ T cell populations during HIV-1 infection.
Small Rho GTPases Mediate Tumor-Induced Inhibition of Endocytic Activity of Dendritic Cells
Authors: Tourkova Irina L. , Shurin Galina V. , Wei Sheng , Shurin Michael R. 
Published: April 2014

Abstract
The generation, maturation, and function of dendritic cells (DC) have been shown to be markedly compromised in the tumor microenvironment in animals and humans. However, the molecular mechanisms and intracellular pathways involved in the regulation of the DC system in cancer are not yet fully understood. Recently, we have reported on the role of the small Rho GTPase family members Cdc42, Rac1, and RhoA in regulating DC adherence, motility, and Ag presentation. To investigate involvement of small Rho GTPases in dysregulation of DC function by tumors, we next evaluated how Cdc42, Rac1, and RhoA regulated endocytic activity of DC in the tumor microenvironment. We revealed a decreased uptake of dextran 40 and polystyrene beads by DC generated in the presence of different tumor cell lines, including RM1 prostate, MC38 colon, 3LL lung, and B7E3 oral squamous cell carcinomas in vitro and by DC prepared from tumor-bearing mice ex vivo. Impaired endocytic activity of DC cocultured with tumor cells was associated with decreased levels of active Cdc42 and Rac1. Transduction of DC with the dominant negative Cdc42 and Rac1 genes also led to reduced phagocytosis and receptor-mediated endocytosis. Furthermore, transduction of DC with the constitutively active Cdc42 and Rac1 genes restored endocytic activity of DC that was inhibited by the tumors. Thus, our results suggest that tumor-induced dysregulation of endocytic activity of DC is mediated by reduced activity of several members of the small Rho GTPase family, which might serve as new targets for improving the efficacy of DC vaccines.
Exposure of Myeloid Dendritic Cells to Exogenous or Endogenous IL-10 during Maturation Determines Their Longevity
Authors: Chang W. L. William , Baumgarth Nicole , Eberhardt Meghan K. , Lee C. Y. Daniel , Baron Colin A. , Gregg Jeff P. , Barry Peter A. 
Published: April 2014

Abstract
Dendritic cells (DC) are essential for the initiation of primary adaptive immune responses, and their functionality is strongly down-modulated by IL-10. Both innate and adaptive immune signals trigger the up-regulation of antiapoptotic Bcl-2 family members to facilitate the survival of DCs after maturation. However, whether IL-10 alters the expression of apoptotic-related genes in maturing DCs has not been determined. In this study, we demonstrate that spontaneous apoptosis rapidly occurred in myeloid DCs exposed to exogenous IL-10 upon maturation. Microarray analysis indicates that IL-10 suppressed the induction of three antiapoptotic genes, bcl-2, bcl-x, and bfl-1, which was coincident with the increased sensitivity of mature DCs to spontaneous apoptosis. IL-10 markedly inhibited the accumulation of steady state Bcl-2 message and protein in myeloid DCs activated through TLRs or TNFR family members, whereas exogenous IL-10 affected Bcl-xL expression in a moderate manner. In contrast, bcl-2 expression of plasmacytoid DCs was less sensitive to the effects of IL-10. We further show that autocrine IL-10 significantly limited the longevity of myeloid DCs and altered the expression kinetics of Bcl-2 but not Bcl-xL in maturing DCs. We conclude that the degree of IL-10 exposure and/or the level of endogenous IL-10 production upon myeloid DC maturation play a critical role in determining DC longevity. This regulatory mechanism of IL-10 is associated with the dynamic control of antiapoptotic Bcl-2 proteins.
Immunomodulatory Effects of Viral TLR Ligands on Experimental Asthma Depend on the Additive Effects of IL-12 and IL-10
Authors: Sel Serdar , Wegmann Michael , Sel Sarper , Bauer Stefan , Garn Holger , Alber Gottfried , Renz Harald 
Published: April 2014

Abstract
Based on epidemiological data, the hygiene hypothesis associates poor hygienic living conditions during childhood with a lower risk for the development of allergic diseases such as bronchial asthma. The role of viral infections, and especially of viral TLR ligands, within this context remains to be clarified. Viral TLR ligands involve dsRNA and ssRNA which are recognized by TLR-3 or TLR-7, respectively. In this study, we evaluated the impact of TLR-3 or TLR-7 activation on experimental asthma in mice. Systemic application of the synthetic TLR-3 or TLR-7 ligands polycytidylic-polyinosinic acid (p(I:C)) or R-848, respectively, during the sensitization phase prevented the production of OVA-specific IgE and IgG1 Abs and subsequently abolished all features of experimental asthma including airway hyperresponsiveness and allergic airway inflammation. Furthermore, administration of p(I:C) or R-848 to animals with already established primary allergic responses revealed a markedly reduced secondary response following allergen aerosol rechallenges. In contrast to wild-type animals, application of p(I:C) or R-848 to IL-12p35−/− mice had no effect on airway inflammation, goblet cell hyperplasia, and airway hyperresponsiveness. However, in the absence of IL-12, the numbers of eosinophils and lymphocytes in bronchoalveolar lavage fluids were still significantly reduced. These partial effects could also be abolished by neutralizing anti-IL-10 Abs in IL-12p35−/− mice. These data indicate that TLR-3 or TLR-7 activation by viral TLR ligands has both preventive as well as suppressive effects on experimental asthma which is mediated by the additive effects of IL-12 and IL-10.
Identification and Characterization of Novel Bone Marrow Myeloid DEC205+Gr-1+ Cell Subsets That Differentially Express Chemokine and TLRs
Authors: Lamb Roberta J. , Capocasale Renold J. , Duffy Karen E. , Sarisky Robert T. , Mbow M. Lamine 
Published: April 2014

AbstractBone marrow-derived immunomodulatory cytokines impart a critical function in the regulation of innate immune responses and hemopoiesis. However, the source of immunomodulatory cytokines in murine bone marrow and the cellular immune mechanisms that control local cytokine secretion remain poorly defined. Herein, we identified a population of resident murine bone marrow myeloid DEC205+CD11c−B220−Gr1+CD8α−CD11b+ cells that respond to TLR2, TLR4, TLR7, TLR8, and TLR9 agonists as measured by the secretion of proinflammatory and anti-inflammatory cytokines in vitro. Phenotypic and functional analyses revealed that DEC205+CD11b+Gr-1+ bone marrow cells consist of heterogeneous populations of myeloid cells that can be divided into two main cell subsets based on chemokine and TLR gene expression profile. The DEC205+CD11b+Gr-1low cell subset expresses high levels of TLR7 and TLR9 and was the predominant source of IL-6, TNF-α, and IL-12 p70 production following stimulation with the TLR7 and TLR9 agonists CpG and R848, respectively. In contrast, the DEC205+CD11b+Gr-1high cell subset did not respond to CpG and R848 stimulation, which correlated with their lack of TLR7 and TLR9 expression. Similarly, a differential chemokine receptor expression profile was observed with higher expression of CCR1 and CXCR2 found in the DEC205+CD11+Gr-1high cell subset. Thus, we identified a previously uncharacterized population of resident bone marrow cells that may be implicated in the regulation of local immune responses in the bone marrow.
Low-Dose Peptide Tolerance Therapy of Lupus Generates Plasmacytoid Dendritic Cells That Cause Expansion of Autoantigen-Specific Regulatory T Cells and Contraction of Inflammatory Th17 Cells
Authors: Kang Hee-Kap , Liu Michael , Datta Syamal K. 
Published: April 2014

Abstract
Subnanomolar doses of an unaltered, naturally occurring nucleosomal histone peptide epitope, H471–94, when injected s.c. into lupus-prone mice, markedly prolong lifespan by generating CD4+25+ and CD8+ regulatory T cells (Treg) producing TGF-β. The induced Treg cells suppress nuclear autoantigen-specific Th and B cells and block renal inflammation. Splenic dendritic cells (DC) captured the s.c.-injected H471–94 peptide rapidly and expressed a tolerogenic phenotype. The DC of the tolerized animal, especially plasmacytoid DC, produced increased amounts of TGF-β, but diminished IL-6 on stimulation via the TLR-9 pathway by nucleosome autoantigen and other ligands; and those plasmacytoid DC blocked lupus autoimmune disease by simultaneously inducing autoantigen-specific Treg and suppressing inflammatory Th17 cells that infiltrated the kidneys of untreated lupus mice. Low-dose tolerance with H471–94 was effective even though the lupus immune system is spontaneously preprimed to react to the autoepitope. Thus, H471–94 peptide tolerance therapy that preferentially targets pathogenic autoimmune cells could spare lupus patients from chronically receiving toxic agents or global immunosuppressants and maintain remission by restoring autoantigen-specific Treg cells.
Novel Suppressive Function of Transitional 2 B Cells in Experimental Arthritis
Authors: Evans Jamie G. , Chavez-Rueda Karina A. , Eddaoudi Ayad , Meyer-Bahlburg Almut , Rawlings David J. , Ehrenstein Michael R. , Mauri Claudia 
Published: April 2014

Abstract
The immune system contains natural regulatory cells important in the maintenance of tolerance. Although this suppressive function is usually attributed to CD4 regulatory T cells, recent reports have revealed an immunoregulatory role for IL-10-producing B cells in the context of several autoimmune diseases including collagen-induced arthritis. In the present study, we attribute this suppressive function to a B cell subset expressing high levels of CD21, CD23, and IgM, previously identified as transitional 2-marginal zone precursor (T2-MZP) B cells. T2-MZP B cells are present in the spleens of naive mice and increase during the remission phase of arthritis. Following adoptive transfer to immunized DBA/1 mice, T2-MZP B cells significantly prevented new disease and ameliorated established disease. The suppressive effect on arthritis was paralleled by an inhibition of Ag-specific T cell activation and a reduction in cells exhibiting Th1-type functional responses. We also provide evidence that this regulatory subset mediates its suppression through the secretion of suppressive cytokines and not by cell-to-cell contact. The ability to regulate an established immune response by T2-MZP B cells endows this subset of B cells with a striking and previously unrecognized immunoregulatory potential.