bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dengue Virus-Reactive CD8+ T Cells Display Quantitative and Qualitative Differences in Their Response to Variant Epitopes of Heterologous Viral Serotypes
Authors: Bashyam Hema S. , Green Sharone , Rothman Alan L. 
Published: April 2014

Abstract
Reactivation of serotype cross-reactive CD8+ memory T lymphocytes is thought to contribute to the immunopathogenesis of dengue disease during secondary infection by a heterologous serotype. Using cytokine flow cytometry, we have defined four novel HLA-A*02-restricted dengue viral epitopes recognized by up to 1.5% of circulating CD8+ T cells in four donors after primary vaccination. All four donors had the highest cytokine response to the epitope NS4b 2353. We also studied the effect of sequence differences in heterologous dengue serotypes on dengue-reactive CD8+ memory T cell cytokine and proliferative responses. The D3 variant of a different NS4b epitope 2423 and the D2 variant of the NS4a epitope 2148 induced the largest cytokine response, compared with their respective heterologous sequences in all donors regardless of the primary vaccination serotype. Stimulation with variant peptides also altered the relative frequencies of the various subsets of cells that expressed IFN-γ, TNF-α, MIP-1β, and combinations of these cytokines. These results indicate that the prior infection history of the individual as well as the serotypes of the primary and heterologous secondary viruses influence the nature of the secondary response. These differences in the effector functions of serotype cross-reactive memory T cells induced by heterologous variant epitopes, which are both quantitative and qualitative, may contribute to the clinical outcome of secondary dengue infection.
Quantitative Analysis of Phosphotyrosine Signaling Networks Triggered by CD3 and CD28 Costimulation in Jurkat Cells
Authors: Kim Ji-Eun , White Forest M. 
Published: April 2014

Abstract
The mechanism by which stimulation of coreceptors such as CD28 contributes to full activation of TCR signaling pathways has been intensively studied, yet quantitative measurement of costimulation effects on functional TCR signaling networks has been lacking. In this study, phosphotyrosine networks triggered by CD3, CD28, or CD3 and CD28 costimulation were analyzed by site-specific quantitative phosphoproteomics, resulting in identification of 101 tyrosine and 3 threonine phosphorylation sites and quantification of 87 sites across four cell states. As expected, CD3 stimulation induced phosphorylation of CD3 chains and upstream components of TCR pathways such as Zap70, while CD28 stimulation induced phosphorylation of CD28, Vav-1, and other adaptor proteins including downstream of tyrosine kinase 1, Grb2-associated protein 2 (Grap2), and Wiskott-Aldrich syndrome protein. CD3 and CD28 costimulation induced a complex response including decreased threonine phosphorylation in the ERK1 and ERK2 activation loops and increased phosphorylation of selected tyrosine sites on ERK1/2, p38, phospholipase C-γ, Src homology 2 domain-containing transforming protein 1, Grap2, and Vav-1, potentiating T cell activation. Hierarchical clustering and self-organizing maps were used to identify modules of coregulated phosphorylation sites within the network. Quantitative information in our study suggests quantitative and qualitative contribution by costimulation of CD28 on CD3-stimulated TCR signaling networks via enhanced phosphorylation of phospholipase C-γ/Src homology 2 domain-containing transforming protein 1/Grap2/Vav-1 and their effects on downstream components including MAPKs.
Self-Limitation of Th1-Mediated Inflammation by IFN-γ
Authors: Feuerer Markus , Eulenburg Katharina , Loddenkemper Christoph , Hamann Alf , Huehn Jochen 
Published: April 2014

Abstract
IFN-γ is an effector cytokine of cell-mediated immunity that plays an essential role in both innate and adaptive phases of an immune response. Interestingly, in several Th1-dependent autoimmune models, lack of IFN-γ is associated with an acceleration of disease. To distinguish the influence of IFN-γ on the polarization of naive precursors from the influence on effector cells, we used an adoptive transfer model of differentiated Ag-specific Th1 cells. In this study, IFN-γ displayed a dual function in a Th1-dependent immune reaction. In the early phase, IFN-γ accelerated the inflammation, whereas in the late phase it mediated the process of self-limitation. We demonstrated that IFN-γ limits the number of Th1 effector cells after Ag challenge. Studies using IFN-γR−/− mice as recipients showed that IFN-γ acts indirectly via host cells to regulate the pool size of Th1 cells. NO was a downstream effector molecule. Transfer experiments of Th1 cells into IFN-γ−/− mice revealed that Th1 cells control both themselves and the corresponding inflammation by the release of IFN-γ. Thus, the proinflammatory cytokine IFN-γ can act as a negative feedback regulator to control Th1-mediated immune responses.
Resistance to Experimental Autoimmune Encephalomyelitis and Impaired IL-17 Production in Protein Kinase Cθ-Deficient Mice
Authors: Tan Seng-Lai , Zhao Jingyong , Bi Chen , Chen XinYi Cynthia , Hepburn Deena L. , Wang Jian , Sedgwick Jonathon D. , Chintalacharuvu Subba R. , Na Songqing 
Published: April 2014

Abstract
The protein kinase Cθ (PKCθ) serine/threonine kinase has been implicated in signaling of T cell activation, proliferation, and cytokine production. However, the in vivo consequences of ablation of PKCθ on T cell function in inflammatory autoimmune disease have not been thoroughly examined. In this study we used PKCθ-deficient mice to investigate the potential involvement of PKCθ in the development of experimental autoimmune encephalomyelitis, a prototypic T cell-mediated autoimmune disease model of the CNS. We found that PKCθ−/− mice immunized with the myelin oligodendrocyte glycoprotein (MOG) peptide MOG35–55 were completely resistant to the development of clinical experimental autoimmune encephalomyelitis compared with wild-type control mice. Flow cytometric and histopathological analysis of the CNS revealed profound reduction of both T cell and macrophage infiltration and demyelination. Ex vivo MOG35–55 stimulation of splenic T lymphocytes from immunized PKCθ−/− mice revealed significantly reduced production of the Th1 cytokine IFN-γ as well as the T cell effector cytokine IL-17 despite comparable levels of IL-2 and IL-4 and similar cell proliferative responses. Furthermore, IL-17 expression was dramatically reduced in the CNS of PKCθ−/− mice compared with wild-type mice during the disease course. In addition, PKCθ−/− T cells failed to up-regulate LFA-1 expression in response to TCR activation, and LFA-1 expression was also significantly reduced in the spleens of MOG35–55-immunized PKCθ−/− mice as well as in in vitro-stimulated CD4+ T cells compared with wild-type mice. These results underscore the importance of PKCθ in the regulation of multiple T cell functions necessary for the development of autoimmune disease.
Directed Differentiation of Human Embryonic Stem Cells into Functional Dendritic Cells through the Myeloid Pathway
Authors: Slukvin Igor I. , Vodyanik Maxim A. , Thomson James A. , Gumenyuk Maryna E. , Choi Kyung-Dal 
Published: April 2014

Abstract
We have established a system for directed differentiation of human embryonic stem (hES) cells into myeloid dendritic cells (DCs). As a first step, we induced hemopoietic differentiation by coculture of hES cells with OP9 stromal cells, and then, expanded myeloid cells with GM-CSF using a feeder-free culture system. Myeloid cells had a CD4+CD11b+CD11c+CD16+CD123lowHLA-DR− phenotype, expressed myeloperoxidase, and included a population of M-CSFR+ monocyte-lineage committed cells. Further culture of myeloid cells in serum-free medium with GM-CSF and IL-4 generated cells that had typical dendritic morphology; expressed high levels of MHC class I and II molecules, CD1a, CD11c, CD80, CD86, DC-SIGN, and CD40; and were capable of Ag processing, triggering naive T cells in MLR, and presenting Ags to specific T cell clones through the MHC class I pathway. Incubation of DCs with A23187 calcium ionophore for 48 h induced an expression of mature DC markers CD83 and fascin. The combination of GM-CSF with IL-4 provided the best conditions for DC differentiation. DCs obtained with GM-CSF and TNF-α coexpressed a high level of CD14, and had low stimulatory capacity in MLR. These data clearly demonstrate that hES cells can be used as a novel and unique source of hemopoietic and DC precursors as well as DCs at different stages of maturation to address essential questions of DC development and biology. In addition, because ES cells can be expanded without limit, they can be seen as a potential scalable source of cells for DC vaccines or DC-mediated induction of immune tolerance.
Unique Structural Determinants for Stat3 Recruitment and Activation by the Granulocyte Colony-Stimulating Factor Receptor at Phosphotyrosine Ligands 704 and 744
Authors: Shao Huang , Xu Xuejun , Jing Naijie , Tweardy David J. 
Published: April 2014

Abstract
G-CSFR cytoplasmic tyrosine (Y) residues (Y704, Y729, Y744, and Y764) become phosphorylated upon ligand binding and recruit specific Src homology 2 domain-containing proteins that link to distinct yet overlapping programs for myeloid cell survival, differentiation, proliferation, and activation. The structural basis for recruitment specificity is poorly understood but could be exploited to selectively target deleterious G-CSFR-mediated signaling events such as aberrant Stat3 activation demonstrated in a subset of acute myeloid leukemia patients with poor prognosis. Recombinant Stat3 bound to G-CSFR phosphotyrosine peptide ligands pY704VLQ and pY744LRC with similar kinetics. Testing of three models for Stat3 Src homology 2-pY ligand binding in vitro and in vivo revealed unique determinants for Stat3 recruitment and activation by the G-CSFR, the side chain of Stat3 R609, which interacts with the pY ligand phosphate group, and the peptide amide hydrogen of E638, which bonds with oxygen/sulfur within the + 3 Q/C side chain of the pY ligand when it assumes a β turn. Thus, our findings identify for the first time the structural basis for recruitment and activation of Stat3 by the G-CSFR and reveal unique features of this interaction that can be exploited to target Stat3 activation for the treatment of a subset of acute myeloid leukemia patients.
Lack of Tyrosine 320 Impairs Spontaneous Endocytosis and Enhances Release of HLA-B27 Molecules
Authors: Santos Susana G. , Antoniou Antony N. , Sampaio Paula , Powis Simon J. , Arosa Fernando A. 
Published: April 2014

Abstract
Several lines of evidence suggest that endocytosis of MHC class I molecules requires conserved motifs within the cytoplasmic domain. In this study, we show, in the C58 rat thymoma cell line transfected with HLA-B27 molecules, that replacement of the highly conserved tyrosine (Tyr320) in the cytoplasmic domain of HLA-B27 does not hamper cell surface expression of β2-microglobulin H chain heterodimers or formation of misfolded molecules. However, Tyr320 replacement markedly impairs spontaneous endocytosis of HLA-B27. Although wild-type molecules are mostly internalized via endosomal compartments, Tyr320-mutated molecules remain at the plasma membrane in which partial colocalization with endogenous transferrin receptors can be observed, also impairing their endocytosis. Finally, we show that Tyr320 substitution enhances release of cleaved forms of HLA-B27 from the cell surface. These studies show for the first time that Tyr320 is most likely part of a cytoplasmic sorting motif involved in spontaneous endocytosis and shedding of MHC class I molecules.
Evidence That Complement Protein C1q Interacts with C-Reactive Protein through Its Globular Head Region
Authors: McGrath Fabian D. G. , Brouwer Mieke C. , Arlaud Gérard J. , Daha Mohamed R. , Hack C. Erik , Roos Anja 
Published: April 2014

Abstract
C1q acts as the recognition unit of the first complement component, C1, and binds to immunoglobulins IgG and IgM, as well as to non-Ig ligands, such as C-reactive protein (CRP). IgG and IgM are recognized via the globular head regions of C1q (C1qGR), whereas CRP has been postulated to interact with the collagen-like region (C1qCLR). In the present study, we used a series of nine mAbs to C1q, five directed against C1qGR and four against C1qCLR, to inhibit the interaction of C1q with CRP. The F(ab′)2 of each of the five mAbs directed against C1qGR inhibited binding of C1q to polymerized IgG. These five mAbs also successfully inhibited the interaction of C1q with CRP. Moreover, these five mAbs inhibited C1 activation by CRP as well as by polymerized IgG in vitro. In contrast, none of the four mAbs against C1qCLR inhibited C1q interaction with CRP or IgG, or could reduce activation of complement by CRP or polymerized IgG. These results provide the first evidence that the interaction of C1q with CRP or IgG involves sites located in the C1qGR, whereas sites in the CLR do not seem to be involved in the physiological interaction of C1q with CRP.
Amino-Terminal Flanking Residues Determine the Conformation of a Peptide–Class II MHC Complex
Authors: Lovitch Scott B. , Pu Zheng , Unanue Emil R. 
Published: April 2014

AbstractThe peptide spanning residues 48–62 of hen egg white lysozyme presented by I-Ak molecules gives rise to two T cell populations, types A and B, that recognize distinct conformers of the complex generated in late and recycling endosomes. The class II–like accessory molecule H2-DM functions as a conformational editor, eliminating the type B conformer in late endosomes. Here, we show that the conformation of the complex, and its susceptibility to editing by H2-DM, are determined by peptide amino-terminal flanking residues. Elimination of these residues abolished editing, permitting formation of the type B conformer in late endosomes. Substitutions at P(−2) affected the stability of the type B conformer, preventing its formation and/or editing, without hindering peptide binding or formation of the type A conformer of the complex. We conclude that interactions involving amino-terminal flanking residues stabilize peptide-MHC conformers and confer resistance to editing by H2-DM, influencing the nature of the T cell repertoire.
Pituitary Adenylate Cyclase-Activating Polypeptide 27 Is a Functional Ligand for Formyl Peptide Receptor-Like 1
Authors: Kim Youndong , Lee Byoung Dae , Kim Oekyung , Bae Yoe-Sik , Lee Taehoon , Suh Pann-Ghill , Ryu Sung Ho 
Published: April 2014

Abstract
Although the neuropeptide pituitary adenylate cyclase-activating polypeptide (PACAP) has been implicated in the regulation of several immune responses, its target receptors and signaling mechanisms have yet to be fully elucidated in immune cells. In this study, we found that PACAP27, but not PACAP38, specifically stimulated intracellular calcium mobilization and ERK phosphorylation in human neutrophils. Moreover, formyl peptide receptor-like 1 (FPRL1) was identified as a PACAP27 receptor, and PACAP27 was found to selectively stimulate intracellular calcium increase in FPRL1-transfected rat basophile leukocytes-2H3 cell lines. In addition, PACAP27-induced calcium increase and ERK phosphorylation were specifically inhibited by an FPRL1 antagonist, Trp-Arg-Trp-Trp-Trp-Trp (WRW4), thus supporting the notion that PACAP27 acts on FPRL1. In terms of the functional role of PACAP27, we found that the peptide stimulated CD11b surface up-regulation and neutrophil chemotactic migration, and that these responses were completely inhibited by WRW4. The interaction between PACAP27 and FPRL1 was analyzed further using truncated PACAPs and chimeric PACAPs using vasoactive intestinal peptide, and the C-terminal region of PACAP27 was found to perform a vital function in the activation of FPRL1. Taken together, our study suggests that PACAP27 activates phagocytes via FPRL1 activation, and that this results in proinflammatory behavior, involving chemotaxis and the up-regulation of CD11b.
Molecular Genetic Analysis of the Idd4 Locus Implicates the IFN Response in Type 1 Diabetes Susceptibility in Nonobese Diabetic Mice
Authors: Ivakine Evgueni A. , Gulban Omid M. , Mortin-Toth Steven M. , Wankiewicz Ellen , Scott Christopher , Spurrell David , Canty Angelo , Danska Jayne S. 
Published: April 2014

Abstract
High-resolution mapping and identification of the genes responsible for type 1 diabetes (T1D) has proved difficult because of the multigenic etiology and low penetrance of the disease phenotype in linkage studies. Mouse congenic strains have been useful in refining Idd susceptibility loci in the NOD mouse model and providing a framework for identification of genes underlying complex autoimmune syndromes. Previously, we used NOD and a nonobese diabetes-resistant strain to map the susceptibility to T1D to the Idd4 locus on chromosome 11. Here, we report high-resolution mapping of this locus to 1.4 megabases. The NOD Idd4 locus was fully sequenced, permitting a detailed comparison with C57BL/6 and DBA/2J strains, the progenitors of T1D resistance alleles found in the nonobese diabetes-resistant strain. Gene expression arrays and quantitative real-time PCR were used to prioritize Idd4 candidate genes by comparing macrophages/dendritic cells from congenic strains where allelic variation was confined to the Idd4 interval. The differentially expressed genes either were mapped to Idd4 or were components of the IFN response pathway regulated in trans by Idd4. Reflecting central roles of Idd4 genes in Ag presentation, arachidonic acid metabolism and inflammation, phagocytosis, and lymphocyte trafficking, our combined analyses identified Alox15, Alox12e, Psmb6, Pld2, and Cxcl16 as excellent candidate genes for the effects of the Idd4 locus.
Expression of B7-H1 on Gastric Epithelial Cells: Its Potential Role in Regulating T Cells during Helicobacter pylori Infection
Authors: Das Soumita , Suarez Giovanni , Beswick Ellen J. , Sierra Johanna C. , Graham David Y. , Reyes Victor E. 
Published: April 2014

Abstract
Helicobacter pylori infection is associated with gastritis, ulcers, and gastric cancer. The infection becomes chronic as the host response is unable to clear it. Gastric epithelial cells (GEC) play an important role during the host response, and their expression of class II MHC and costimulatory molecules such as CD80 and CD86 suggests their role in local Ag presentation. Although T cells are recruited to the infected gastric mucosa, they have been reported to be hyporesponsive. In this study, we detected the expression of B7-H1 (programmed death-1 ligand 1), a member of B7 family of proteins associated with T cell inhibition on GEC. Quantitative real-time RT-PCR revealed that B7-H1 expression increased significantly on GEC after H. pylori infection. Western blot analysis showed that B7-H1 expression was induced by various H. pylori strains and was independent of H. pylori virulence factors such as Cag, VacA, and Urease. The functional role of B7-H1 in the cross talk between GEC and T cells was assessed by coculturing GEC or H. pylori-infected GEC with CD4+ T cells isolated from peripheral blood. Using blocking Abs to B7-H1 revealed that B7-H1 was involved in the suppression of T cell proliferation and IL-2 synthesis, and thus suggested a role for B7-H1 on the epithelium as a contributor in the chronicity of H. pylori infection.
Potent Inhibition of Macrophage Responses to IFN-γ by Live VirulentMycobacterium tuberculosisIs Independent of Mature Mycobacterial Lipoproteins but Dependent on TLR2
Authors: Banaiee Niaz , Kincaid Eleanor Z. , Buchwald Ulrike , Jacobs William R. , Ernst Joel D. 
Published: April 2014

AbstractMycobacterium tuberculosis is a highly successful pathogen that can persist and cause disease despite an immune response. One potential mechanism for resisting elimination is by inhibiting the action of IFN-γ. We have previously shown that live M. tuberculosis inhibits selected macrophage responses to IFN-γ, and that purified M. tuberculosis 19-kDa lipoprotein inhibits induction of selected IFN-γ-responsive genes through a TLR2-dependent pathway, whereas peptidoglycan inhibits responses to IFN-γ by a TLR2-independent pathway. To determine the relative contribution of lipoproteins to the inhibition of responses to IFN-γ, we deleted the M. tuberculosis gene (lspA) that encodes lipoprotein signal peptidase. This revealed that M. tuberculosis lipoprotein processing is indispensable for stimulation of TLR2 reporter cells, but that the lspA mutant inhibits macrophage responses to IFN-γ to the same extent as wild-type bacteria. Macrophages lacking TLR2 are more resistant to inhibition by either strain of M. tuberculosis, suggesting that nonlipoprotein TLR2 agonists contribute to inhibition. Indeed, we found that phosphatidylinositol mannan from M. tuberculosis inhibits macrophage responses to IFN-γ. M. tuberculosis inhibition of responses to IFN-γ requires new protein synthesis, indicating that a late effect of innate immune stimulation is the inhibition of responses to IFN-γ. These results establish that M. tuberculosis possesses multiple mechanisms of inhibiting responses to IFN-γ.
Cryptococcus neoformans Glycoantigens Are Captured by Multiple Lectin Receptors and Presented by Dendritic Cells
Authors: Mansour Michael K. , Latz Eicke , Levitz Stuart M. 
Published: April 2014

Abstract
Cell-mediated immune responses to glycoantigens have been largely uncharacterized. Protective T cell responses to the pathogenic yeast Cryptococcus neoformans are dependent on heavily mannosylated Ags termed mannoproteins. In the work presented, the innate immune response to mannoprotein was determined. Purified murine splenic dendritic cells (DC), B cells, and macrophages were used to stimulate mannoprotein-specific T cells. Only DC were capable of any measurable stimulation. Depletion of DC resulted in the abrogation of the T cell response. Human and murine DC rapidly captured fluorescent-labeled mannoprotein by a mannose receptor-mediated process. Using transfected cell lines, the type II C-type lectin receptor DC-specific ICAM-3-grabbing nonintegrin (CD209) was determined to have affinity for mannoprotein. Taken together with prior work demonstrating that mannoprotein was captured by the macrophage mannose receptor (CD206), these data suggest that multiple mannose receptors on DC recognize mannoprotein. Pulsing experiments demonstrated that DC captured sufficient mannoprotein over 2 h to account for 50% of total stimulation. Capture appeared dependent on mannose receptors, as competitive mannosylated inhibitors and calcium chelators each interfered with T cell stimulation. By confocal microscopy, intracellular mannoprotein trafficked to an endo-lysosomal compartment in DC, and at later time points extended into tubules in a similar fashion to the degradation marker DQ-OVA. Mannoprotein colocalized intracellularly with CD206 and CD209. These data suggest that DC provide the crucial link between innate and adaptive immune responses to C. neoformans via a process that is dependent upon the efficient uptake of mannoprotein by mannose receptors.