bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Intra-Peyer’s Patch Gene Transfer Model for Studying Mucosal Tolerance: Distinct Roles of B7 and IL-12 in Mucosal T Cell Tolerance
Authors: Chen Yiguang , Song Kaimei , Eck Stephen L. , Chen Youhai 
Published: April 2014

AbstractDevelopment of mucosal immunity and tolerance requires coordinated expression of a number of genes within the mucosa-associated lymphoid tissue (MALT). To study the roles of these genes in the MALT, we have established a MALT-specific gene transfer model using replication-defective adenovirus as vector. In this model, the target gene of interest is directly delivered into the Peyer’s patch by intra-Peyer’s patch injection of the recombinant virus. Using this gene transfer model, we investigated the roles of B7-1 and IL-12 in the development of mucosal tolerance. We found that intra-Peyer’s patch injection of OVA induced Ag-specific T cell hyporesponsiveness, as manifested by decreased T cell proliferation and IL-2/IFN-γ production upon subsequent immune challenge. Intra-Peyer’s patch B7-1 gene transfer at the time of OVA administration partially reversed the inhibition of T cell proliferation and IL-2 secretion, but had no effect on IFN-γ production. By contrast, intra-Peyer’s patch IL-12 gene transfer completely restored T cell proliferation and IFN-γ secretion and partially reversed IL-2 inhibition. Using an adoptive TCR transgenic model, we further demonstrated that B7 and IL-12 played distinct roles during the inductive phase of mucosal tolerance. B7 selectively increased T cell proliferation and IL-2 secretion without affecting IFN-γ production, whereas IL-12 increased both IL-2 and IFN-γ production. These results indicate that B7 alone may not be sufficient to abrogate mucosal tolerance, and that cytokines such as IL-12 may also be required. Based on these findings, we propose a new model to explain the paradoxical roles of B7 in mucosal immunity and tolerance.
Exposure to Ultraviolet Radiation Causes Dendritic Cells/Macrophages to Secrete Immune-Suppressive IL-12p40 Homodimers
Authors: Schmitt David A. , Ullrich Stephen E. 
Published: April 2014

Abstract
UV-induced immune suppression is a risk factor for sunlight-induced skin cancer. Exposure to UV radiation has been shown to suppress the rejection of highly antigenic UV-induced skin cancers, suppresses delayed and contact hypersensitivity, and depress the ability of dendritic cells to present Ag to T cells. One consequence of UV exposure is altered activation of T cell subsets. APCs from UV-irradiated mice fail to present Ag to Th1 T cells; however, Ag presentation to Th2 T cells is normal. While this has been known for some time, the mechanism behind the preferential suppression of Th1 cell activation has yet to be explained. We tested the hypothesis that this selective impairment of APC function results from altered cytokine production. We found that dendritic cells/macrophages (DC/Mφ) from UV-irradiated mice failed to secrete biologically active IL-12 following in vitro stimulation with LPS. Instead, DC/Mφ isolated from the lymphoid organs of UV-irradiated mice secreted IL-12p40 homodimer, a natural antagonist of biologically active IL-12. Furthermore, when culture supernatants from UV-derived DC/Mφ were added to IL-12-activated T cells, IFN-γ secretion was totally suppressed, indicating that the IL-12p40 homodimer found in the supernatant fluid was biologically active. We suggest that by suppressing DC/Mφ IL-12p70 secretion while promoting IL-12p40 homodimer secretion, UV exposure preferentially suppress the activation of Th1 cells, thereby suppressing Th-1 cell-driven inflammatory immune reactions.
Subset-Specific Regulation of the Lymphatic Exit of Recirculating Lymphocytes In Vivo
Authors: Young Alan J. , Marston Wendy L. , Dudler Lisbeth 
Published: April 2014

Abstract
The blood-to-lymph recirculation of lymphocytes is required for the maintenance of immune surveillance and the dissemination of memory. Although the ability of lymph-borne cells to recirculate has been well documented, relatively less is known about the migration capacity of PBLs. We have found a clear preference for PBLs to recirculate through s.c. rather than intestinal lymph nodes. This preference could be directly attributed to the migratory characteristics of γδ-T cells. γδ-T cells were found to express significantly higher levels of L-selectin than other subsets, suggesting that at least some of this preferential migration could be attributed to their interaction with ligands on vascular endothelium. More detailed experiments showed that γδ-T cells migrated through lymph nodes with greater efficiency than αβ T cells or B cells, which clearly indicated an enhanced ability of γδ-T cells to exit lymph nodes in the efferent lymph independent of entry from the blood. This hypothesis was supported by histological examination, where γδ-T cells were found almost exclusively in the interfollicular traffic areas within lymph nodes. These data indicate that γδ-T cells are the most active recirculating lymphocyte subset in ruminants and suggest new mechanisms to regulate the traffic of lymphocyte subsets through normal lymph nodes.
Nonstandard Peptide Binding Revealed by Crystal Structures of HLA-B*5101 Complexed with HIV Immunodominant Epitopes
Authors: Maenaka Katsumi , Maenaka Taeko , Tomiyama Hiroko , Takiguchi Masafumi , Stuart David I. , Jones E. Yvonne 
Published: April 2014

Abstract
The crystal structures of the human MHC class I allele HLA-B*5101 in complex with 8-mer, TAFTIPSI, and 9-mer, LPPVVAKEI, immunodominant peptide epitopes from HIV-1 have been determined by x-ray crystallography. In both complexes, the hydrogen-bonding network in the N-terminal anchor (P1) pocket is rearranged as a result of the replacement of the standard tyrosine with histidine at position 171. This results in a nonstandard positioning of the peptide N terminus, which is recognized by B*5101-restricted T cell clones. Unexpectedly, the P5 peptide residues appear to act as anchors, drawing the peptides unusually deeply into the peptide-binding groove of B51. The unique characteristics of P1 and P5 are likely to be responsible for the zig-zag conformation of the 9-mer peptide and the slow assembly of B*5101. A comparison of the surface characteristics in the α1-helix C-terminal region for B51 and other MHC class I alleles highlights mainly electrostatic differences that may be important in determining the specificity of human killer cell Ig-like receptor binding.
Pepsin-Mediated Processing of the Cytoplasmic Histone H2A to Strong Antimicrobial Peptide Buforin I
Authors: Kim Hun Sik , Yoon Ho , Minn Il , Park Chan Bae , Lee Won Taek , Zasloff Michael , Kim Sun Chang 
Published: April 2014

Abstract
The intestinal epithelium forms a first line of innate host defense by secretion of proteins with antimicrobial activity against microbial infection. Despite the extensive studies on the antimicrobial host defense in many gastrointestinal tracts, little is known about the antimicrobial defense system of the stomach. The potent antimicrobial peptide buforin I, consisting of 39 aa, was isolated recently from the stomach tissue of an Asian toad, Bufo bufo gargarizans. In this study we examined the mechanism of buforin I production in toad stomach tissue. Buforin I is produced by the action of pepsin isozymes, named pepsin Ca and Cb, cleaving the Tyr39-Ala40 bond of histone H2A. Immunohistochemical analysis revealed that buforin I is present extracellularly on the mucosal surface, and unacetylated histone H2A, a precursor of buforin I, is localized in the cytoplasm of gastric gland cells. Furthermore, Western blot analysis showed that buforin I is also present in the gastric fluids, and immunoelectron microscopy detected localization of the unacetylated histone H2A in the cytoplasmic granules of gastric gland cells. The distinct subcellular distribution of the unacetylated histone H2A and the detection of the unacetylated buforin I both on the mucosal surface and in the lumen suggest that buforin I is produced from the cytoplasmic unacetylated histone H2A secreted into the gastric lumen and subsequently processed by pepsins. Our results indicate that buforin I along with pepsins in the vertebrate stomach may contribute to the innate host defense of the stomach against invading microorganisms.
Dual Role of the HIV-1 Vpr Protein in the Modulation of the Apoptotic Response of T Cells
Authors: Conti Lucia , Matarrese Paola , Varano Barbara , Gauzzi Maria Cristina , Sato Akihiko , Malorni Walter , Belardelli Filippo , Gessani Sandra 
Published: April 2014

Abstract
We investigated the effect of vpr, physiologically expressed during the course of an acute HIV-1 infection, on the response of infected cells to apoptotic stimuli as well as on the HIV-induced apoptosis. At 48 h after infection, Jurkat cells exhibited a lower susceptibility to undergo apoptosis with respect to uninfected cells. This effect was not observed following infection with either a vpr-mutated virus or a wild-type strain in the presence of antisense oligodeoxynucleotides targeted at vpr mRNA. Single-cell analysis, aimed at simultaneously identifying apoptotic and infected cells, revealed that resistance to apoptosis correlated with productive infection. Notably, vpr-dependent protection from induced apoptosis was also observed in HIV-1-infected PBMC. In contrast, at later stages of infection, a marked increase in the number of cells spontaneously undergoing apoptosis was detected in infected cultures. This virus-induced apoptosis involved vpr expression and predominantly occurred in productively infected cells. These results indicate that HIV-1 vpr can exert opposite roles in the regulation of apoptosis, which may depend on the level of its intracellular expression at different stages of HIV-1 infection. The dual function of vpr represents a novel mechanism in the complex strategy evolved by HIV to influence the turnover of T lymphocytes leading to either viral persistence or virus release and spreading.
The B Subunit of Shiga Toxin Fused to a Tumor Antigen Elicits CTL and Targets Dendritic Cells to Allow MHC Class I-Restricted Presentation of Peptides Derived from Exogenous Antigens
Authors: Haicheur Nacilla , Bismuth Emmanuelle , Bosset Sophie , Adotevi Olivier , Warnier Guy , Lacabanne Valérie , Regnault Armelle , Desaymard Catherine , Amigorena Sebastian , Ricciardi-Castagnoli Paola , Goud Bruno , Fridman Wolf H. , Johannes Ludger , Tartour Eric 
Published: April 2014

Abstract
Immunization with peptide or recombinant proteins generally fails to elicit CTL, which are thought to play a key role in the control of virus-infected cells and tumor growth. In this study we show that the nontoxic B subunit of Shiga toxin fused to a tumor peptide derived from the mouse mastocytoma P815 can induce specific CTL in mice without the use of adjuvant. The Shiga B subunit acts as a vector rather than as an adjuvant, because coinjection of the tumor peptide and the B subunit as separate entities does not lead to CTL induction. We also demonstrated that in vitro the B subunit mediates the delivery of various exogenous CD8 T cell epitopes into the conventional MHC class I-restricted pathway, as this process is inhibited by brefeldin A and lactacystin and requires a functional TAP system. In contrast to other nonviral methods for transport of exogenous Ags into the endogenous MHC class I pathway that involve macropinocytosis or phagocytosis, the Shiga B subunit targets this pathway in a receptor-dependent manner, namely via binding to the glycolipid Gb3. Because this receptor is highly expressed on various dendritic cells, it should allow preferential targeting of the Shiga B subunit to these professional APCs. Therefore, the Shiga B subunit appears to represent an attractive vector for vaccine development due to its ability to target dendritic cells and to induce specific CTL without the need for adjuvant.
Nitric Oxide Is Neither Necessary Nor Sufficient for Resolution ofPlasmodium chabaudiMalaria in Mice
Authors: van der Heyde Henri C. , Gu Yang , Zhang Qiang , Sun Guang , Grisham Matthew B. 
Published: April 2014

AbstractMalaria is a life-threatening re-emerging disease, yet it is still not clear how bloodstage malarial parasites are killed. Nitric oxide (NO), which has potent anti-microbial activity, may represent an important killing mechanism. The production of NO during descending Plasmodium chabaudi parasitemia, a period when parasites are killed by the immune response, supports this concept. However, NOS20/0 and NOS30/0 mice as well as mice treated with NO synthase 2 (NOS2) inhibitors do not develop exacerbated malaria, indicating that NO production is not necessary for the suppression of P. chabaudi parasitemia. It is possible due to the plasticity in the immune response during malaria that Ab-mediated immunity is enhanced in the absence of NO, thereby explaining the lack of exacerbated malaria in NOS-deficient mice even though NO may function in protection. However, NOS2- and B cell-deficient mice, which cannot use Ab-mediated immunity, suppress their parasitemia with a similar time course as B cell-deficient controls. C57BL/6 mice treated with Propionibacterium acnes to elicit high levels of macrophage-derived NO have a similar time course of P. chabaudi parasitemia as P. acnes-treated NOS20/0 mice, which do not produce NO; this indicates that NO is not sufficient for parasite killing. Collectively, these results indicate that NO is not necessary or sufficient to resolve P. chabaudi malaria.
Autoantibody Responses and Pathology Regulated by B7-1 and B7-2 Costimulation in MRL/lprLupus
Authors: Liang Bailin , Kashgarian Michael J. , Sharpe Arlene H. , Mamula Mark J. 
Published: April 2014

AbstractThe activation of T lymphocytes requires both Ag-mediated signaling through the TCR as well as costimulatory signals transmitted through B7-1 and/or B7-2 with CD28. The interference of B7-mediated costimulatory signals has been proposed as one immunotherapeutic intervention for the prevention autoimmune disease. This study has examined autoantibody responses and autoimmune pathology in a murine model of human systemic lupus erythematosus (SLE), the MRL-lpr/lpr mouse, genetically deficient in B7-1 or B7-2, or in mice treated with B7-1/B7-2 blocking Abs. In contrast to other studies of murine models of SLE, MRL-lpr/lpr mice treated with B7 blocking Abs exhibit strong anti-small nuclear ribonucleoprotein (snRNP) and anti-DNA autoantibody responses with some changes in isotype switching as compared with untreated animals. All MRL-lpr/lpr mice deficient in B7-1 or B7-2 produce anti-snRNP and anti-DNA titers with isotypes virtually identical with wild-type animals. However, the absence of B7-2 costimulation did interfere with the spontaneous activation and the accumulation of memory CD4+ or CD8+ T lymphocytes characteristic of wild-type MRL-lpr/lpr mice. IgG and C3 complement deposition was less pronounced in the kidneys of B7-2 deficient MRL-lpr/lpr mice, reflecting their lessor degree of glomerulonephritis. By comparison, B7-1-deficient MRL-lpr/lpr mice had more severe IgG and C3 deposits in glomeruli.
Respiratory Infection with Influenza A Virus Interferes with the Induction of Tolerance to Aeroallergens
Authors: Tsitoura Daphne C. , Kim Sung , Dabbagh Karim , Berry Gerald , Lewis David B. , Umetsu Dale T. 
Published: April 2014

Abstract
Viral respiratory infections have been implicated in influencing allergen sensitization and the development of asthma, but their exact role remains controversial. Because respiratory exposure to Ag normally engenders T cell tolerance and prevents the development of airway hyperreactivity (AHR) and inflammation, we examined the effects of influenza A virus infection on tolerance induced by exposure to intranasal (i.n.) OVA and the subsequent development of AHR. We found that concurrent infection with influenza A abrogated tolerance induced by exposure to i.n. OVA, and instead led to the development of AHR accompanied by the production of OVA-specific IgE, IL-4, IL-5, IL-13, and IFN-γ. When both IL-4 and IL-5 were neutralized in this system, AHR was still induced, suggesting that influenza-induced cytokines such as IL-13, or mechanisms unrelated to cytokines, might be responsible for the development of AHR. The length of time between influenza A infection and i.n. exposure to OVA was crucial, because mice exposed to i.n. OVA 15–30 days after viral inoculation developed neither AHR nor OVA-specific tolerance. These mice instead acquired Th1-biased OVA-specific immune responses associated with vigorous OVA-induced T cell proliferation, and reduced production of OVA-specific IgE. The protective effect of influenza A on AHR was dependent on IFN-γ, because protection was abrogated with a neutralizing anti-IFN-γ mAb. These results suggest that viral respiratory infection interferes with the development of respiratory allergen-induced tolerance, and that the time interval between viral infection and allergen exposure is critical in determining whether viral infection will enhance, or protect against, the development of respiratory allergen sensitization and AHR.
Host CD40 Ligand Deficiency Induces Long-Term Allograft Survival and Donor-Specific Tolerance in Mouse Cardiac Transplantation But Does Not Prevent Graft Arteriosclerosis
Authors: Shimizu Koichi , Schönbeck Uwe , Mach François , Libby Peter , Mitchell Richard N. 
Published: April 2014

AbstractAlthough interruption of CD40-CD40L interactions via their respective mAbs yields prolonged allograft survival, the relative importance of CD40 or CD40L on donor or host cells remains unknown. Moreover, it is uncertain whether any allospecific tolerance occurring with CD40-CD40L blockade will also prevent allograft arteriopathy, the major long-term limitation to transplantation. Therefore, we performed cardiac transplantations using CD40L-deficient (CD40L−/−) mice to investigate the mechanisms underlying prolonged allograft survival. Without immunosuppression, wild-type (WT) hosts rejected allo-mismatched WT or CD40L−/− heart allografts within 2 wk. Conversely, allografts in CD40L−/− hosts beat vigorously for 12 wk. Anti-CD40 treatment did not induce graft failure in CD40L−/− recipients. Although graft-infiltrating cells were reduced ∼50% in CD40L−/− hosts, the relative percentages of macrophages and T cell subsets were comparable to WT. IFN-γ, TNF-α, and IL-10 were diminished commensurate with the reduced cellular infiltrate; IL-4 was not detected. CD40L−/− recipients did not develop IgG alloantibodies and showed diminished B7 and CD28 expression on subsets of graft-infiltrating cells. CD40L−/− transplant recipients developed allospecific tolerance to the donor haplotype; second set donor skin grafts engrafted well, whereas third-party skin grafts were vigorously rejected. By MLR, splenocytes from CD40L−/− allograft recipients also demonstrated allo-specific hyporesponsiveness. Nevertheless, allografts in CD40L−/− hosts developed significant graft arteriosclerosis by 8–12 wk posttransplant. Therefore, we propose that early alloresponses, without CD40-CD40L costimulation, induce allospecific tolerance but may trigger allo-independent mechanisms that ultimately result in graft vasculopathy.
Cutting Edge: Lipopolysaccharide Induces Physical Proximity Between CD14 and Toll-Like Receptor 4 (TLR4) Prior to Nuclear Translocation of NF-κB
Authors: Jiang Qingqi , Akashi Sachiko , Miyake Kensuke , Petty Howard R. 
Published: April 2014

AbstractCD14, a GPI-linked protein, plays a pivotal role in LPS-mediated signaling by potentiating leukocyte adherence, activation, and cytokine production. Recent studies have identified the Toll-like receptor 4 (TLR4) as a membrane cofactor in LPS-mediated transmembrane signaling in cytokine induction, although the mechanism responsible for this cooperation is unknown. Using fluorescence resonance energy transfer (RET) techniques, we demonstrate that LPS triggers a physical association between CD14 and TLR4. Because LPS stimulation up-regulates CD14 and TLR4 expression, it was necessary to control for the possibility that these newly expressed molecules were associated with one another independent of LPS stimulation. Although the calcium ionophore A23187 increased the expression of CD14 and TLR4, they did not exhibit energy transfer. However, following A23187 treatment, LPS promoted physical proximity between CD14 and TLR4. Therefore, we suggest that a close interaction between CD14 and TLR4 participates in LPS signaling, leading to nuclear translocation of NF-κB.
Cutting Edge: NK Cell Inhibitory Receptors Prevent Tyrosine Phosphorylation of the Activation Receptor 2B4 (CD244)
Authors: Watzl Carsten , Stebbins Christopher C. , Long Eric O. 
Published: April 2014

Abstract2B4 is an NK cell activation receptor that can provide a costimulatory signal to other activation receptors and whose mode of signal transduction is still unknown. We show that cross-linking of 2B4 on NK cells results in its rapid tyrosine phosphorylation, implying that this initial step in 2B4 signaling does not require coligation of other receptors. Ligation of 2B4 in the context of an NK cell-target cell interaction leads to 2B4 tyrosine phosphorylation, target cell lysis, and IFN-γ release. Coligation of 2B4 with the inhibitory receptors killer cell Ig-like receptor (KIR)2DL1 or CD94/NKG2 completely blocks NK cell activation. The rapid tyrosine phosphorylation of 2B4 observed upon contact of NK cells with sensitive target cells is abrogated when KIR2DL1 or CD94/NKG2 are engaged by their cognate MHC class I ligand on resistant target cells. These results demonstrate that NK inhibitory receptors can interfere with a step as proximal as phosphorylation of an activation receptor.
Differential Requirement of ZAP-70 for CD2-Mediated Activation Pathways of Mature Human T Cells
Authors: Meinl Edgar , Lengenfelder Doris , Blank Norbert , Pirzer Rainer , Barata Luis , Hivroz Claire 
Published: April 2014

AbstractThis study addresses the role of the tyrosine kinase ZAP-70 in CD2-mediated T cell activation. Patients lacking ZAP-70 have few mature CD8+ T cells and high numbers of CD4+ T cells that are nonfunctional upon TCR triggering. Such a patient with a homozygous deletion in the zap-70 gene that resulted in the complete absence of ZAP-70 protein expression has been identified. Expression of the tyrosine kinases Lck, Fyn, and Syk was normal. The patient’s T cells were activated with two different pairs of mitogenic mAbs. CD2-induced phosphorylation of the ζ-chain and influx of Ca2+ was defective in the ZAP-70-deficient T cells, whereas CD2-induced phosphorylation of several other proteins, including Syk, was not affected. CD2-induced proliferation as well as production of TNF-α and IFN-γ was abrogated in ZAP-70-deficient T cells, whereas PMA plus ionomycin induced normal activation of these cells. Together, this study shows that CD2-activation triggers ZAP-70-dependent and -independent pathways. Deletion of ZAP-70 affected CD2- and CD3-mediated proliferation and cytokine production in a similar way, suggesting that one of the different CD2 pathways converges with a CD3 pathway at or upstream of the activation of ZAP-70.