bluuebunny/crossref_metadata_2025_split huggingface dataset:
Receptor-Binding Domain of Severe Acute Respiratory Syndrome Coronavirus Spike Protein Contains Multiple Conformation-Dependent Epitopes that Induce Highly Potent Neutralizing Antibodies
Authors: He Yuxian , Lu Hong , Siddiqui Pamela , Zhou Yusen , Jiang Shibo 
Published: April 2014

Abstract
The spike (S) protein of severe acute respiratory syndrome associated coronavirus (SARS-CoV) is a major antigenic determinant capable of inducing protective immunity. Recently, a small fragment on the SARS-CoV S protein (residues 318–510) was characterized as a minimal receptor-binding domain (RBD), which mediates virus binding to angiotensin-converting enzyme 2, the functional receptor on susceptible cells. In this study, we demonstrated that a fusion protein containing RBD linked to human IgG1 Fc fragment (designated RBD-Fc) induced high titer of RBD-specific Abs in the immunized mice. The mouse antisera effectively neutralized infection by both SARS-CoV and SARS pseudovirus with mean 50% neutralization titers of 1/15,360 and 1/24,737, respectively. The neutralization determinants on the RBD of S protein were characterized by a panel of 27 mAbs isolated from the immunized mice. Six groups of conformation-dependent epitopes, designated as Conf I–VI, and two adjacent linear epitopes were identified by ELISA and binding competition assays. The Conf IV and Conf V mAbs significantly blocked RBD-Fc binding to angiotensin-converting enzyme 2, suggesting that their epitopes overlap with the receptor-binding sites in the S protein. Most of the mAbs (23 of 25) that recognized the conformational epitopes possessed potent neutralizing activities against SARS pseudovirus with 50% neutralizing dose ranging from 0.005 to 6.569 μg/ml. Therefore, the RBD of SARS S protein contains multiple conformational epitopes capable of inducing potent neutralizing Ab responses, and is an important target site for developing vaccines and immunotherapeutics.
Apoptosis Induced by the Toll-Like Receptor Adaptor TRIF Is Dependent on Its Receptor Interacting Protein Homotypic Interaction Motif
Authors: Kaiser William J. , Offermann Margaret K. 
Published: April 2014

AbstractTLRs detect specific molecular features of microorganisms and subsequently engage distinct signaling networks through the differential use of Toll/IL-1R (TIR)-domain-containing adapter proteins. In this study, we investigated the control of apoptosis by the TIR domain-containing adapter proteins MyD88, TIR-domain containing adapter protein (TIRAP), TIR-domain-containing adapter-inducing IFN-β (TRIF), TRIF-related adapter molecule (TRAM), and sterile α motifs and β-catenin/armadillo repeats (SARM). Upon overexpression, TRIF was the sole TIR-adapter to potently engage mammalian cell death signaling pathways. TRIF-induced cell death required caspase activity initiated by the Fas/Apo-1-associated DD protein-caspase-8 axis and was unaffected by inhibitors of the intrinsic apoptotic machinery. The proapoptotic potential of TRIF mapped to the C-terminal region that was found to harbor a receptor interacting protein (RIP) homotypic interaction motif (RHIM). TRIF physically interacted with the RHIM-containing proteins RIP1 and RIP3, and deletion and mutational analyses revealed that the RHIM in TRIF was essential for TRIF-induced apoptosis and contributed to TRIF-induced NF-κB activation. The domain that was required for induction of apoptosis could activate NF-κB but not IFN regulatory factor-3, yet the activation of NF-κB could be blocked by superrepressor IκBα without blocking apoptosis. Thus, the ability of TRIF to induce apoptosis was not dependent on its ability to activate either IFN regulatory factor-3 or NF-κB but was dependent on the presence of an intact RHIM. TRIF serves as an adaptor for both TLR3 and TLR4, receptors that are activated by dsRNA and LPS, respectively. These molecular motifs are encountered during viral and bacterial infection, and the apoptosis that occurs when TRIF is engaged represents an important host defense to limit the spread of infection.
Dominant Role for TL1A/DR3 Pathway in IL-12 plus IL-18-Induced IFN-γ Production by Peripheral Blood and Mucosal CCR9+ T Lymphocytes
Authors: Papadakis Konstantinos A. , Zhu Daocheng , Prehn John L. , Landers Carol , Avanesyan Armine , Lafkas Gina , Targan Stephan R. 
Published: April 2014

AbstractThe TNF-like cytokine TL1A augments IFN-γ production by anti-CD3 plus anti-CD28 and IL-12/IL-18-stimulated peripheral blood (PB) T cells. However, only a small subset of PB T cells respond to TL1A stimulation with IFN-γ production. PB CCR9+ T cells represent a small subset of circulating T cells with mucosal T cell characteristics and a Th1/Tr1 cytokine profile. In the current study, we show that TL1A enhanced IFN-γ production by TCR- or CD2/CD28-stimulated CCR9+CD4+ PB T cells. However, TL1A had the most pronounced effect on augmenting IFN-γ production by IL-12/IL-18-primed CCR9+CD4+ PB T cells. TL1A enhanced both the percentage and the mean fluorescence intensity of IFN-γ in CCR9+CD4+ T cells as assessed by intracellular cytokine staining. IL-12 plus IL-18 up-regulated DR3 expression in CCR9+CD4+ T cells but had negligible effect on CCR9−CD4+ T cells. CCR9+CD4+ T cells isolated from the small intestine showed a 37- to 105-fold enhancement of IFN-γ production when TL1A was added to the IL-12/IL18 cytokine combination. Cell membrane-expressed TL1A was preferentially expressed in CCR9+CD4+ PB T cells, and a blocking anti-TL1A mAb inhibited IFN-γ production by cytokine-primed CCR9+CD4+ T cells by ∼50%. Our data show that the TL1A/DR3 pathway plays a dominant role in the ultimate level of cytokine-induced IFN-γ production by CCR9+ mucosal and gut-homing PB T cells and could play an important role in Th1-mediated intestinal diseases, such as Crohn’s disease, where increased expression of IL-12, IL-18, TL1A, and DR3 converge in the inflamed intestinal mucosa.
A2A Adenosine Receptors on Bone Marrow-Derived Cells Protect Liver from Ischemia-Reperfusion Injury
Authors: Day Yuan-Ji , Li Yuesheng , Rieger Jayson M. , Ramos Susan I. , Okusa Mark D. , Linden Joel 
Published: April 2014

AbstractActivation of the A2A adenosine receptor (A2AR) during reperfusion of various tissues has been found to markedly reduce ischemia-reperfusion injury. In this study, we used bone marrow transplantation (BMT) to create chimeric mice that either selectively lack or selectively express the A2AR on bone marrow-derived cells. Bolus i.p. injection of the selective A2A agonist, 4-{3-[6-amino-9-(5-cyclopropylcarbamoyl-3,4-dihydroxy-tetrahydro-furan-2-yl)-9H-purin-2-yl]-prop-2-ynyl}-piperidine-1-carboxylic acid methyl ester (ATL313; 3 μg/kg), at the time of reperfusion protects wild-type (wt) mice from liver ischemia-reperfusion injury. ATL313 also protects wt/wt (donor/recipient BMT mouse chimera) and wt/knockout chimera but produces modest protection of knockout/wt chimera as assessed by alanine aminotransferase activity, induction of cytokine transcripts (RANTES, IFN-γ-inducible protein-10, IL-1α, IL-1-β, IL-1Rα, IL-18, IL-6, and IFN-γ), or histological criteria. ATL313, which is highly selective for the A2AR, produces more liver protection of chimeric BMT mice than 4-{3-[6-amino-9-(5-ethylcarbamoyl-3,4-dihydroxy-tetrahydro-furan-2-yl)-9H-purin-2-yl]-prop-2-ynyl}-cyclohexanecarboxylic acid methyl ester, which is rapidly metabolized in mice to produce 4-{3-[6-amino-9-(5-ethylcarbamoyl-3,4-dihydroxy-tetrahydro-furan-2-yl)-9H-purin-2-yl]-prop-2-ynyl}-cyclohexanecarboxylic acid, which has similar affinity for the A2AR and the proinflammatory A3 adenosine receptor. GFP chimera mice were created to show that vascular endothelial cells in the injured liver do not account for liver protection because they are not derived by transdifferentiation of bone marrow precursors. The data suggest that activation of the A2AR on bone marrow-derived cells is primarily responsible for protecting the liver from reperfusion injury.
Coinfection withSchistosoma mansoniIs Associated with Decreased HIV-Specific Cytolysis and Increased IL-10 Production
Authors: McElroy Michael D. , Elrefaei Mohamed , Jones Norman , Ssali Francis , Mugyenyi Peter , Barugahare Banson , Cao Huyen 
Published: April 2014

AbstractImpaired virus-specific immune responses have previously been observed with Schistosoma mansoni coinfection. We characterized Gag-specific responses in HIV-1-positive Ugandans with and without S. mansoni coinfection. We observed no significant difference in the frequency of IFN-γ CD8+ T cells between the two groups. Interestingly, expression of CD107, a marker for cytolytic activity, was significantly lower in volunteers with S. mansoni coinfection compared with those with HIV-1 infection alone (p = 0.002). In contrast, the frequency of IL-10-positive Gag-specific CD8+ T cell responses was higher in volunteers with S. mansoni coinfection (p = 0.004). Analysis of human CMV-specific CD8+ T cell responses in the same individuals failed to reveal a similar pattern of altered CD107 and IL-10 expression. Our results suggest that S. mansoni coinfection is associated with decreased Gag-specific CD8+ cytolytic T cell responses and increased number of Gag-specific IL-10 positive CD8+ T cells. Our findings may have important implications toward the implementation of HIV preventive and therapeutic programs in Africa.
Effects of Increasing IL-7 Availability on Lymphocytes during and after Lymphopenia-Induced Proliferation
Authors: Bosco Nabil , Agenès Fabien , Ceredig Rhodri 
Published: April 2014

AbstractIL-7 is critically involved in regulating peripheral T cell homeostasis. To investigate the role of IL-7 on lymphopenia-induced proliferation of polyclonal lymphocytes, we have transferred CFSE-labeled cells into a novel T-lymphopenic, IL-7-transgenic mouse line. Results obtained indicate that T and B cells do not respond in the same way to IL-7-homeostatic signals. Overexpression of IL-7 enhances proliferation of both CD4+ and CD8+ T cells but with distinctly temporal effects. Expansion of naturally arising CD4+-regulatory T cells was like that of conventional CD4+ T cells. IL-7 had no effect on B cell proliferation. By immunohistology, transferred T cells homed to T cell areas of spleen lymphoid follicles. Increasing IL-7 availability enhanced T cell recovery by promoting cell proliferation and reducing apoptosis during early stages of lymphopenia-induced proliferation. Taken together, these results provide new insights into the pleiotropic effects of IL-7 on lymphopenia-induced T cell proliferation.
Refining the Rules of Gliadin T Cell Epitope Binding to the Disease-Associated DQ2 Molecule in Celiac Disease: Importance of Proline Spacing and Glutamine Deamidation
Authors: Qiao Shuo-Wang , Bergseng Elin , Molberg Øyvind , Jung Günther , Fleckenstein Burkhard , Sollid Ludvig M. 
Published: April 2014

Abstract
Celiac disease is driven by intestinal T cells responsive to proline-rich gluten peptides that often harbor glutamate residues formed by tissue transglutaminase-mediated glutamine conversion. The disease is strongly associated with the HLA variant DQ2.5 (DQA1*05, DQB1*02), and intestinal gluten-reactive T cells from DQ2.5-positive patients are uniquely restricted by this HLA molecule. In this study, we describe the mapping of two novel T cell epitopes of γ-gliadin and the experimental identification of the DQ2.5 binding register of these and three other γ-gliadin epitopes. The new data extend the knowledge base for understanding the binding of gluten peptides to DQ2.5. The alignment of the experimentally determined binding registers of nine gluten epitopes reveal positioning of proline residues in positions P1, P3, P6, and P8 but never in positions P2, P4, P7, and P9. Glutamate residues formed by tissue transglutaminase-mediated deamidation are found in position P1, P4, P6, P7, or P9, but only deamidations in positions P4 and P6, and rarely in P7, seem to be crucial for T cell recognition. The majority of these nine epitopes are recognized by celiac lesion T cells when presented by the related but nonassociated DQ2.2 (DQA1*0201, DQB1*02) molecule. Interestingly, the DQ2.2 presentation for most epitopes is less efficient than presentation by the DQ2.5 molecule, and this is particularly prominent for the α-gliadin epitopes. Contrary to previous findings, our data do not show selective presentation of DQ2.5 over DQ2.2 for gluten epitopes that carry proline residues at the P3 position.
Cellular FLIP Long Form Augments Caspase Activity and Death of T Cells through Heterodimerization with and Activation of Caspase-8
Authors: Dohrman Austin , Russell Jennifer Q. , Cuenin Solange , Fortner Karen , Tschopp Jürg , Budd Ralph C. 
Published: April 2014

AbstractCaspase activity is required not only for the death of T cells, but also for their activation. A delicate balance of caspase activity is thus required during T cell activation at a level that will not drive cell death. How caspase activity is initiated and regulated during T cell activation is not known. One logical candidate for this process is cellular FLIP long form (c-FLIPL), because it can block caspase-8 recruitment after Fas (CD95) ligation as well as directly heterodimerize with and activate caspase-8. The current findings demonstrate that after T cell activation, caspase-8 and c-FLIPL associate in a complex enriched for active caspases. This occurs coincidently with the cleavage of two known caspase-8 substrates, c-FLIPL and receptor interacting protein 1. Caspase activity is higher in wild-type CD8+ than CD4+ effector T cells. Increased expression of c-FLIPL results in augmented caspase activity in resting and effector T cells to levels that provoke cell death, especially of the CD8 subset. c-FLIPL is thus not only an inhibitor of cell death by Fas, it can also act as a principal activator of caspases independently of Fas.
The Chicken Leukocyte Receptor Complex: A Highly Diverse Multigene Family Encoding at Least Six Structurally Distinct Receptor Types
Authors: Viertlboeck Birgit C. , Habermann Felix A. , Schmitt Ramona , Groenen Martien A. M. , Du Pasquier Louis , Göbel Thomas W. 
Published: April 2014

Abstract
The chicken Ig-like receptors (CHIR) have been described as two Ig domain molecules with long cytoplasmic tails containing inhibitory motifs. In this study, we demonstrate that CHIR form a large family, with multiple members showing great sequence variability among members as well as a great diversity in domain organization and properties of the transmembrane and cytoplasmic segments. We characterize various novel receptor types with motifs indicative of inhibitory, activating, or both functions. In addition to the inhibitory receptors with two ITIM, receptors with a single immunoreceptor tyrosine-based switch motif or receptors lacking a cytoplasmic domain were isolated. Activating receptors with a short cytoplasmic domain and a transmembrane arginine assembled with the newly identified chicken FcεRIγ chain. Three bifunctional receptor types were characterized composed of one or two C2-type Ig-like domains, a transmembrane region with a positively charged residue and combinations of cytoplasmic motifs such as ITIM, immunoreceptor tyrosine-based switch motif, and YXXM. RT-PCR revealed distinct expression patterns of individual CHIR. All receptor types shared a conserved genomic architecture, and in single Ig domain receptors a pseudoexon replaced the second Ig exon. Southern blot analyses with probes specific for the Ig1 domain were indicative of a large multigene family. Of 103 sequences from the Ig1 domain of a single animal, 41 unique sequences were obtained that displayed extensive variability within restricted Ig regions. Fluorescence in situ hybridization localized the CHIR gene cluster to microchromosome 31 and identified this region as orthologous to the human leukocyte receptor complex.
Human-Like Immune Responses in CD46 Transgenic Mice
Authors: Johansson Linda , Rytkönen Anne , Wan Hong , Bergman Peter , Plant Laura , Agerberth Birgitta , Hökfelt Tomas , Jonsson Ann-Beth 
Published: April 2014

Abstract
Neisseria meningitidis is a major cause of sepsis and/or meningitis. These bacteria normally cause disease only in humans, however, mice expressing human CD46 are susceptible to meningococcal disease. To explain the sensitivity of CD46 transgenic mice to meningococci, we evaluated early immune responses. Stimulation of TNF, IL-6, and IL-10 was stronger in CD46 transgenic mice compared with nontransgenic mice, and resembled human responses. In CD46 transgenic mice, bacterial clearance in blood started at later time points, and neutrophil numbers in blood were lower compared with nontransgenic mice. Further, elevated levels of activated microglia cells and cyclooxygenase-2 were observed in brain of infected CD46 transgenic mice. Intraperitoneal administration of meningococci lead to increased levels of macrophages only in the i.p. cavity of CD46 transgenic mice. Most of the responses were impaired or absent using LPS-deficient meningococci, showing the importance of LPS in the early immune response to meningococcal infection. Taken together, these data demonstrate that responses in mice expressing human CD46 mimic human meningococcal disease in many aspects, and demonstrate novel important links between CD46 and the innate immune system.
Neutrophil-Mediated Maturation of Chemerin: A Link between Innate and Adaptive Immunity
Authors: Wittamer Valérie , Bondue Benjamin , Guillabert Aude , Vassart Gilbert , Parmentier Marc , Communi David 
Published: April 2014

Abstract
Dendritic cells and macrophages are professional APCs that play a central role in initiating immune responses, linking innate and adaptive immunity. Chemerin is a novel chemoattractant factor that specifically attracts APCs through its receptor ChemR23. Interestingly, chemerin is secreted as a precursor of low biological activity, prochemerin, which upon proteolytic removal of a C-terminal peptide, is converted into a potent and highly specific agonist of its receptor. Given the fact that APCs are often preceded by polymorphonuclear cells (PMN) in inflammatory infiltrates, we hypothesized that PMN could mediate chemerin generation. We demonstrate here that human degranulated PMNs release proteases that efficiently convert prochemerin into active chemerin. The use of specific protease inhibitors allowed us to identify the neutrophil serine proteases cathepsin G and elastase as responsible for this process. Mass spectrometry analysis of processed prochemerin showed that each protease generates specifically a distinct form of active chemerin, differing in their C terminus and initially identified in human inflammatory fluids. These findings strongly suggest that bioactive chemerin generation takes place during the early stages of inflammation, underscoring the functional contribution of chemerin as a bridge between innate and adaptive immunity.
Differential Involvement of BB Loops of Toll-IL-1 Resistance (TIR) Domain-Containing Adapter Proteins in TLR4- versus TLR2-Mediated Signal Transduction
Authors: Toshchakov Vladimir U. , Basu Subhendu , Fenton Matthew J. , Vogel Stefanie N. 
Published: April 2014

AbstractTLRs sense pathogens and transmit intracellular signals via the use of specific adapter proteins. We designed a set of “blocking peptides” (BPs) comprised of the 14 aa that correspond to the sequences of the BB loops of the four known Toll-IL-1 resistance (TIR) domain-containing adapter proteins (i.e., MyD88, TIR domain-containing adapter inducing IFN-β (TRIF), TRIF-related adapter molecule (TRAM), and TIR-domain containing adapter protein (TIRAP)) linked to the cell-penetrating segment of the antennapedia homeodomain. LPS (TLR4)-mediated gene expression, as well as MAPK and transcription factor activation associated with both MyD88-dependent and -independent signaling pathways, were disrupted by all four BPs (TRAM ≈ MyD88 &gt; TRIF &gt; TIRAP), but not by a control peptide. In contrast, none of the BPs inhibited TLR2-mediated activation of MAPKs. Only the MyD88 BP significantly blocked Pam3Cys-induced IL-1β mRNA; however, the inhibitory effect was much less than observed for LPS. Our data suggest that the interactions required for a fully functional TLR4 signaling “platform” are disrupted by these BPs, and that the adapter BB loops may serve distinct roles in TLR4 and TLR2 signalosome assembly.
Global Analysis of Smad2/3-Dependent TGF-β Signaling in Living Mice Reveals Prominent Tissue-Specific Responses to Injury
Authors: Lin Amy H. , Luo Jian , Mondshein Lauren H. , ten Dijke Peter , Vivien Denis , Contag Christopher H. , Wyss-Coray Tony 
Published: April 2014

Abstract
Smad2 and Smad3 (Smad2/3) proteins are key signaling molecules for TGF-β and some related family members regulating the transcription of several hundred genes. TGF-β have key roles in development, tissue homeostasis, and the pathogenesis of many human diseases, including cancer, fibrotic disorders, developmental defects, and neurodegeneration. To study the temporal and spatial patterns of Smad2/3-dependent signaling in normal and pathological conditions in the living organism, we engineered transgenic mice with a Smad-responsive luciferase reporter construct (SBE-luc mice). Using bioluminescent imaging, we assessed Smad2/3 signaling activity noninvasively in living mice. At baseline, this activity was highest in brain, intestine, heart, and skin, and correlated with biochemical measurements of reporter activity. Primary astrocytes cultured from SBE-luc mice showed specific activation of the reporter in response to Smad2/3-activating TGF-β family members. Treatment of mice with the endotoxin LPS resulted in a fast and vigorous, but transient activation of the reporter in the intestine. Although the response was similarly rapid in brain, it remained increased, indicating important but different cellular responses to endotoxin challenge in these organs. Traumatic brain injury with a needle stab resulted in local activation of Smad2/3-dependent genes and a severalfold increase in bioluminescence in living mice. SBE-luc mice can therefore be used to study temporal, tissue-specific activation of Smad2/3-dependent signaling in living mice in normal or pathological conditions as well as for the identification of endogenous or synthetic modulators of this pathway.