bluuebunny/crossref_metadata_2025_split huggingface dataset:
Decorin Reverses the Repressive Effect of Autocrine-Produced TGF-β on Mouse Macrophage Activation
Authors: Comalada Mònica , Cardó Marina , Xaus Jordi , Valledor Annabel F. , Lloberas Jorge , Ventura Francesc , Celada Antonio 
Published: April 2014

AbstractSeveral cytokines or growth factors induce macrophages to proliferate, become activated, differentiate, or die through apoptosis. Like the major macrophage activator IFN-γ, the extracellular matrix protein decorin inhibits proliferation and protects macrophages from the induction of apoptosis. Decorin enhances the IFN-γ-induced expression of the IAα and IAβ MHC class II genes. Moreover, it increases the IFN-γ- or LPS-induced expression of inducible NO synthase, TNF-α, IL-1β, and IL-6 genes and the secretion of these cytokines. Using a number of extracellular matrix proteins, we found a negative correlation between adhesion and proliferation. However, the effects of decorin on macrophage activation do not seem to be mediated through its effect on adhesion or proliferation. Instead, this proteoglycan abolishes the binding of TGF-β to macrophages, as shown by Scatchard analysis of 125I-labeled TGF-β, which, in the absence of decorin, showed a Kd of 0.11 ± 0.03 nM and ∼5000 receptors/cell. This was confirmed when we treated macrophages with Abs to block the endogenously produced TGF-β, which enhanced macrophage activation in a way similar to decorin. The increase in activation mediated by decorin demonstrates that macrophages are under negative regulation that can be reversed by proteins of the extracellular matrix.
IL-6 Production by Pulmonary Dendritic Cells Impedes Th1 Immune Responses
Authors: Dodge Ingrid L. , Carr Michelle Woldemar , Cernadas Manuela , Brenner Michael B. 
Published: April 2014

AbstractMucosal tissues, such as the lung, are continually exposed to both foreign and environmental Ags. To counter the potential inflammatory tissue injury of chronic Th1-mediated responses against these Ags, mucosal sites may skew toward Th2 immune responses. However, the mechanism by which this occurs is unknown. Dendritic cells (DC), as orchestrators of the immune response, skew Th1/Th2 differentiation by cytokine secretion and expression of specific cell surface markers. We compared DC from mucosal and systemic locations. In this study, we show that the lung lacks a CD8α+ DC subpopulation and contains DC that appear less mature than splenic DC. Furthermore, we demonstrate that pulmonary DC produce significant levels of IL-6 and fail to produce the Th1-polarizing cytokine IL-12. Importantly, we demonstrate that IL-6 negatively regulates IL-12 production, as pulmonary DC from IL-6−/− mice produce significant levels of IL-12 and induce Th1 polarization of naive CD4+ T cells. Furthermore, we demonstrate that IL-6 is sufficient to explain the differential polarizing abilities of pulmonary and splenic DC, as splenic DC cocultures supplemented with IL-6 polarize naive T cells toward Th2, and pulmonary DC cultures in which IL-6 was removed with neutralizing Ab resulted in more Th1 polarization, pointing to IL-6 as the mechanism of Th2 polarization in the lung. We propose that the Th2 response seen in the lung is due to DC-mediated inhibition of Th1 responses via IL-6 production, rather than enhanced Th2 responses, and that this regulation decreases the likelihood of chronic inflammatory pathology in the lung.
Activation with CpG-A and CpG-B Oligonucleotides Reveals Two Distinct Regulatory Pathways of Type I IFN Synthesis in Human Plasmacytoid Dendritic Cells
Authors: Kerkmann Miren , Rothenfusser Simon , Hornung Veit , Towarowski Andreas , Wagner Moritz , Sarris Anja , Giese Thomas , Endres Stefan , Hartmann Gunther 
Published: April 2014

Abstract
Two different CpG oligonucleotides (ODN) were used to study the regulation of type I IFN in human plasmacytoid dendritic cells (PDC): ODN 2216, a CpG-A ODN, known to induce high amounts of IFN-α in PDC, and ODN 2006, a CpG-B ODN, which is potent at stimulating B cells. CpG-A ODN showed higher and prolonged kinetics of type I IFN production compared with that of CpG-B ODN. In contrast, CpG-B ODN was more active than CpG-A ODN in stimulating IL-8 production and increasing costimulatory and Ag-presenting molecules, suggesting that CpG-A and CpG-B trigger distinct regulatory pathways in PDC. Indeed, CpG-A ODN, but not CpG-B ODN, activated the type I IFNR-mediated autocrine feedback loop. PDC were found to express high constitutive levels of IFN regulatory factor (IRF)7. IRF7 and STAT1, but not IRF3, were equally up-regulated by both CpG-A and CpG-B. CD40 ligand synergistically increased CpG-B-induced IFN-α independent of the IFNR but did not affect CpG-B-induced IFN-β. In conclusion, our studies provide evidence for the existence of two distinct regulatory pathways of type I IFN synthesis in human PDC, one dependent on and one independent of the IFNR-mediated feedback loop. The alternate use of these pathways is based on the type of stimulus rather than the quantity of IFN-αβ available to trigger the IFNR. Constitutive expression of IRF7 and the ability to produce considerable amounts of IFN-α independent of the IFNR seem to represent characteristic features of PDC.
Phosphatidylinositol 3-Kinase Regulates the CD4/CD8 T Cell Differentiation Ratio
Authors: Rodríguez-Borlado Luis , Barber Domingo F. , Hernández Carmen , Rodríguez-Marcos Miguel A. , Sánchez Arsenio , Hirsch Emilio , Wymann Matthias , Martínez-A. Carlos , Carrera Ana C. 
Published: April 2014

AbstractThe signaling pathways that control T cell differentiation have only begun to be elucidated. Using T cell lines, it has been shown that class IA phosphatidylinositol 3-kinase (PI3K), a heterodimer composed of a p85 regulatory and a p110 catalytic subunit, is activated after TCR stimulation. Nonetheless, the contribution of p85/p110 PI3K isoforms in T cell development has not been described. Mice deficient in the other family of class I PI3K, p110γ, which is regulated by G protein-coupled receptors, exhibit reduced thymus size. Here we examine T cell development in p110γ-deficient mice and in mice expressing an activating mutation of the p85 regulatory subunit, p65PI3K, in T cells. We show that p110γ-deficient mice have a partial defect in pre-TCR-dependent differentiation, which is restored after expression of the p65PI3K activating mutation. Genetic alteration of both PI3K isoforms also affects positive selection; p110γ deletion decreased and p65PI3K expression augmented the CD4+/CD8+ differentiation ratio. Finally, data are presented showing that both PI3K isoforms influenced mature thymocyte migration to the periphery. These observations underscore the contribution of PI3K in T cell development, as well as its implication in determining the CD4+/CD8+ T cell differentiation ratio in vivo.
Glatiramer Acetate (Copolymer-1, Copaxone) Promotes Th2 Cell Development and Increased IL-10 Production Through Modulation of Dendritic Cells
Authors: Vieira Pedro L. , Heystek Heleen C. , Wormmeester Jan , Wierenga Eddy A. , Kapsenberg Martien L. 
Published: April 2014

Abstract
Glatiramer acetate (GA; copolymer-1, Copaxone) suppresses the induction of experimental autoimmune encephalomyelitis and reduces the relapse frequency in relapsing-remitting multiple sclerosis. Although it has become clear that GA induces protective degenerate Th2/IL-10 responses, its precise mode of action remains elusive. Because the cytokine profile of Th cells is often regulated by dendritic cells (DC), we studied the modulatory effects of GA on the T cell regulatory function of human DC. This study shows the novel selective inhibitory effect of GA on the production of DC-derived inflammatory mediators without affecting DC maturation or DC immunostimulatory potential. DC exposed to GA have an impaired capacity to secrete the major Th1 polarizing factor IL-12p70 in response to LPS and CD40 ligand triggering. DC exposed to GA induce effector IL-4-secreting Th2 cells and enhanced levels of the anti-inflammatory cytokine IL-10. The anti-inflammatory effect of GA is mediated via DC as GA does not affect the polarization patterns of naive Th cells activated in an APC-free system. Together, these results reveal that APC are essential for the GA-mediated shift in the Th cell profiles and indicate that DC are a prime target for the immunomodulatory effects of GA.
Distinct Pathways for NF-κB Regulation Are Associated with Aberrant Macrophage IL-12 Production in Lupus- and Diabetes-Prone Mouse Strains
Authors: Liu Jiajian , Beller David I. 
Published: April 2014

Abstract
One characteristic of mice prone to a variety of autoimmune diseases is the aberrant regulation of cytokine production by macrophages (Mφ), noted in cells isolated well before the onset of disease. Strikingly, the pattern of IL-12 dysregulation, in particular, is consistent with the nature of the autoimmune disease that will develop in each strain, i.e., elevated in mice prone to Th1-mediated organ-specific disease (nonobese diabetic (NOD) and SJL mice) and reduced in lupus-prone strains (MRL/+ and NZB/W). Mechanistically, the abnormal regulation of IL-12 in these strains was found to be strictly associated with novel patterns of Rel binding in vitro to the unique NF-κB site in the IL-12 p40 promoter. In this study, we report several new findings related to these Rel-κB interactions. Evaluation of the p40 NF-κB site in vivo, assessed by chromatin immunoprecipitation, revealed Rel usage patterns similar to those found in vitro using EMSA, with preferential association of the p40 κB site with c-Rel in NOD Mφ but with p50 in NZB/W Mφ. Moreover, blocking c-Rel in primary Mφ, using short interfering RNA, selectively blocked IL-12 production and normalized the minimal, residual IL-12 levels. Nuclear extracts from NOD Mφ were characterized by c-Rel hyperphosphorylation, and dephosphorylation of nuclear proteins completely blocked binding to the κB site. In contrast, elevated IκB appears to be a likely mechanism accounting for the reduced nuclear c-Rel levels noted in NZB/W Mφ. Alterations in NF-κB metabolism thus appear to define a pathway regulating intrinsic IL-12 defects in both diabetes- and lupus-prone strains.
Determinants of Human B Cell Migration Across Brain Endothelial Cells
Authors: Alter Andrea , Duddy Martin , Hebert Sherry , Biernacki Katarzyna , Prat Alexandre , Antel Jack P. , Yong Voon Wee , Nuttall Robert K. , Pennington Caroline J. , Edwards Dylan R. , Bar-Or Amit 
Published: April 2014

AbstractCirculating B cells enter the CNS as part of normal immune surveillance and in pathologic states, including the common and disabling illness multiple sclerosis. However, little is known about the molecular mechanisms that mediate human B cell interaction with the specialized brain endothelial cells comprising the blood-brain barrier (BBB). We studied the molecular mechanisms that regulate the migration of normal human B cells purified ex vivo, across human adult brain-derived endothelial cells (HBECs). We found that B cells migrated across HBECs more efficiently than T cells from the same individuals. B cell migration was significantly inhibited by blocking Abs to the adhesion molecules ICAM-1 and VLA-4, but not VCAM-1, similar to the results previously reported for T cells. Blockade of the chemokines monocyte chemoattractant protein-1 and IL-8, but not RANTES or IFN-γ-inducible protein-10, significantly inhibited B cell migration, and these results were correlated with the chemokine receptor expression of B cells measured by flow cytometry and by RNase protection assay. Tissue inhibitor of metalloproteinase-1, a natural inhibitor of matrix metalloproteinases, significantly decreased B cell migration across the HBECs. A comprehensive RT-PCR comparative analysis of all known matrix metalloproteinases and tissue inhibitors of metalloproteinases in human B and T cells revealed distinct profiles of expression of these molecules in the different cell subsets. Our results provide insights into the molecular mechanisms that underlie human B cell migration across the BBB. Furthermore, they identify potential common, and unique, therapeutic targets for limiting CNS B cell infiltration and predict how therapies currently developed to target T cell migration, such as anti-VLA-4 Abs, may impact on B cell trafficking.
Homology Between an Alloantigen and a Self MHC Allele Calibrates the Avidity of the Alloreactive T Cell Repertoire Independent of TCR Affinity
Authors: Hornell Tara M. C. , Myers Nancy , Hansen Ted H. , Connolly Janet M. 
Published: April 2014

AbstractThe self-restricted T cell repertoire exhibits a high frequency of alloreactivity. Because these alloreactive T cells are derived from the pool of cells selected on several different self MHC alleles, it is unknown how development of the alloantigenic repertoire is influenced by homology between a self MHC allele and an alloantigen. To address this, we used the 2C transgenic TCR that is selected by Kb, is alloreactive for Ld, and cross-reacts with Lq. Lq is highly homologous to Ld and binds several of the same peptide ligands, including p2Ca, the peptide recognized by 2C. We find that Ld/p2Ca is a high avidity agonist ligand, whereas Lq/p2Ca is a low avidity agonist ligand for 2C T cells. When mice transgenic for the 2C TCR are bred to Lq-expressing mice, 2C+ T cells develop; however, they express lower levels of either the 2C TCR or CD8 and require a higher Ld/p2Ca ligand density to be activated than 2C+ T cells selected by Kb. Furthermore, the 2C T cells selected in the presence of Lq fail to detect Lq/p2Ca complexes even at high ligand density. Thus, despite possessing the identical TCR, there is a functional avidity difference between 2C+ T cells selected in the presence of Lq vs Kb. These data provide evidence that homology between the selecting ligand and an alloantigen can influence the avidity of the T cell repertoire for the alloantigen, and suggest that thymic selection can fine tune T cell avidity independent of intrinsic TCR affinity.
Correction of Defects Responsible for Impaired Qa-2 Class Ib MHC Expression on Melanoma Cells Protects Mice from Tumor Growth
Authors: Chiang Eugene Y. , Henson Maile , Stroynowski Iwona 
Published: April 2014

Abstract
One of the principal mechanisms of tumor immune evasion is alteration of class I MHC expression. We have identified defects contributing to down-regulation of class I MHC expression in the widely studied murine B16 melanoma and its variants B16F1, B16F10, BL6-2, BL6-8 and B78H1. Transcription of the nonclassical class I MHC genes Q8 and Q9 (Qa-2 Ags) has been switched off in the entire panel of melanoma lines, suggesting that this event occurred early during tumor progression. B78H1, unlike B16F1 and B16F10 sublines, is also selectively devoid of TAP2 and low molecular weight protein 7 as well as classical class I MHC Kb and Db transcripts. Cotransfection of B78H1 with TAP2 and class I H chain genes is sufficient to reconstitute surface expression of exogenously delivered class I MHC without concomitant re-expression of endogenous β2-microglobulin-associated class I. The serological absence of endogenous class Ia and Ib at the surface of TAP2-negative as well as TAP2-transfected B78H1 makes this system a suitable model for studying the properties of isolated class I proteins in tumors. We used this system to demonstrate that B78H1 cells genetically manipulated to re-express Q9 Ag have reduced tumor potential in syngeneic B6 mice compared with TAP2-transfected parental melanoma. Both NK cells and CTLs appear to collaborate in restraining growth of Q9-positive tumors. The results implicate Qa-2 in antitumor responses and illustrate the utility of the B78H1 system for identifying in vivo interactions between class I MHC molecules of interest and immune cells of innate and/or adaptive immunity.
IL-7-Regulated Homeostatic Maintenance of Recent Thymic Emigrants in Association with Caspase-Mediated Cell Proliferation and Apoptotic Cell Death
Authors: O’Neill Rose M. , Hassan Jaythoon , Reen Denis J. 
Published: April 2014

AbstractHomeostasis of T cells is essential to the maintenance of the T cell pool and TCR diversity. In this study, mechanisms involved in the regulation of cytokine-mediated expansion of naive T cells in the absence of Ag, in particular the role of caspase activation and susceptibility to apoptosis of recent thymic emigrants (RTEs), were examined. Low level caspase-8 and caspase-3 activation was detected in proliferating IL-7-treated cells in the absence of cell death during the first days of culture. Caspase inhibitors suppressed IL-7-induced expansion of RTEs. Low level expression of CD95 and blocking Ab experiments indicated that this early caspase activation was CD95 independent. However, CD95 levels subsequently became dramatically up-regulated on proliferating naive T cells, and these cells became susceptible to CD95 ligation, resulting in high level caspase activation and apoptotic cell death. These results show a dual role for caspases in proliferation and in CD95-induced cell death during Ag-independent expansion of RTEs. This method of cell death in IL-7-expanded RTEs is a previously unrecognized mechanism for the homeostatic control of expanded T cells.
Study of the Mechanism of TCR Antagonism Using Dual-TCR-Expressing T Cells
Authors: Yang Wen , Grey Howard M. 
Published: April 2014

AbstractThe mechanism of action of TCR antagonists is incompletely understood. T cells expressing two distinct TCRs have been used to test competition for TCR occupancy as a potential mechanism. Previous studies with CD4 T cells showed that an antagonist for one TCR inhibited the response to the other TCR (cross-antagonism), whereas studies with CD8 cells failed to demonstrate cross-antagonism. To determine whether CD4 and CD8 cells were intrinsically different or whether the differences were the result of the use of different effector assays, we studied both CD4 and CD8 dual-TCR-expressing T cells. In the CD4 system, consistent with previous reports, cross-antagonism of proliferation was observed. In the CD8 system, cross-antagonism was observed using proliferation as readout but not when target cell cytolysis was used. These results suggest that different mechanisms may be involved in the inhibition of proliferation and inhibition of cytotoxic effector function, the latter only involving competition for TCR occupancy. Inhibition of proliferation appears to be more complex and other mechanisms such as sequestration of signaling molecules or negative signaling may be involved. The fact that 10- to 20-fold more antagonist was needed to achieve cross-antagonism compared with inhibition of the cognate TCR is consistent with the hypothesis that competition for TCR occupancy is also a major, albeit not sole, mechanism of antagonism of the proliferative responses of CD4 and CD8 cells.
Src Homology Region 2-Containing Protein Tyrosine Phosphatase-2 (SHP-2) Can Play a Direct Role in the Inhibitory Function of Killer Cell Ig-Like Receptors in Human NK Cells
Authors: Yusa Sei-ichi , Campbell Kerry S. 
Published: April 2014

AbstractThe inhibitory forms of killer cell Ig-like receptors (KIR) are MHC class I-binding receptors that are expressed by human NK cells and prevent their attack of normal cells. Substantial evidence indicates that the mechanism of KIR-mediated inhibition involves recruitment of the protein tyrosine phosphatase, Src homology region 2-containing protein tyrosine phosphatase (SHP)-1, to phosphorylated immunoreceptor tyrosine-based inhibitory motifs (ITIMs). However, the functional significance of parallel recruitment of a SHP-1-related phosphatase, SHP-2, to KIR ITIMs has not been addressed. In the present study, our results with mutant forms of a classical KIR, KIR3DL1, show a direct correlation between SHP-2 recruitment and functional inhibition of target cell conjugation and cytotoxicity. In addition, KIR3DL1 inhibition of target cell cytotoxicity is blocked by overexpression of a dominant-negative form of SHP-2. Finally, KIR3DL1 fused directly with the catalytic domain of SHP-2 inhibits both target cell conjugation and cytotoxicity responses. These results strongly indicate that SHP-2 catalytic activity plays a direct role in inhibitory KIR functions, and SHP-2 inhibits NK cell activation in concert with SHP-1.
Murine Neonatal Lymphocytes Show Rapid Early Cell Cycle Entry and Cell Division
Authors: Adkins Becky , Williamson Tonya , Guevara Patricia , Bu Yurong 
Published: April 2014

AbstractNeonatal animals are highly susceptible to infectious agents. At least part of this susceptibility is due to the virtual absence of immunological memory in newborns. One of the hallmarks of memory is the rapidity of the response. We show in this study that neonates may make up for their lack of memory, at least in part, by the rapid entry of large proportions of naive lymphocytes into the cell cycle. Following activation, greater percentages of both CD4+ and CD8+ neonatal, as compared with adult, lymph node cells showed early cell cycle entry; this was assessed by propidium iodide staining, CFSE labeling profiles, [3H]thymidine uptake, and up-regulation of early activation markers. This rapid cycle entry was observed following polyclonal activation with anti-CD3 or with PMA and ionomycin and in both C57BL/6 and BALB/c mice. Stimulation with specific peptide also elicited more rapid proliferative responses from neonatal vs adult TCR transgenic CD4+ cells. In addition, more rapid cycle entry was observed in vivo, in lymphopenic RAG2−/− hosts. For both CD4+ and CD8+ cells, this phenomenon was observed out to 3 wk of life, although the differences between neonatal and adult cells became smaller with increasing time postbirth. These properties of peripheral neonatal T cells appeared to be inherited from their thymic precursors, because CD4+8− single-positive cells in the neonatal thymus also showed more rapid cycle entry, compared with their counterparts in the adult thymus. Interestingly, rapid early cycling was also observed among activated neonatal B cells, compared with adult B cells. Thus, early cell cycle entry by large proportions of cells may allow the naive lymphocyte population to efficiently mobilize responses against the broad range of pathogens first encountered in neonatal life.