bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Role for the Granzyme B Inhibitor Serine Protease Inhibitor 6 in CD8+ Memory Cell Homeostasis
Authors: Phillips Tiphanie , Opferman Joseph T. , Shah Ramila , Liu Ni , Froelich Christopher J. , Ashton-Rickardt Philip G. 
Published: April 2014

Abstract
Generation and maintenance of protective immunological memory is the goal of vaccination programs. It has recently become clear that CD8+ memory T cells are derived directly from CTLs. The mechanisms underlying this transformation and the subsequent survival of memory cells are not completely understood. However, some effector molecules required by CTLs to eliminate infected cells have also been shown to control the number of Ag-specific cells. We report that memory cells express high levels of serine protease inhibitor (Spi) 6, an inhibitor of the effector molecule granzyme B, and that Spi6 can protect T cells from granzyme B-mediated apoptosis. In mouse models, both elevated expression of Spi6 and the complete absence of granzyme B in CD8+ T cells led to an increase in memory cells after infection with lymphocytic choriomeningitis virus. This was not the result of increased levels of antilymphocytic choriomeningitis virus CD8+ T cells during the expansion or contraction phases, but rather transgenic Spi6 directly influenced the survival of CD8+ memory T cells. We propose that expression of protective molecules, like Spi6, serves to shield metabolically active CD8+ memory T cells from their own effector molecules.
A Role for CD28 in Lymphopenia-Induced Proliferation of CD4 T Cells
Authors: Hagen Karin A. , Moses Christina T. , Drasler Erin F. , Podetz-Pedersen Kelly M. , Jameson Stephen C. , Khoruts Alexander 
Published: April 2014

Abstract
The peripheral mechanisms that regulate the size and the repertoire of the T cell compartment during recovery from a lymphopenic state are incompletely understood. In particular, the role of costimulatory signals, such as those provided by CD28, which have a critical importance for the immune response toward foreign Ags in nonlymphopenic animals, has been unclear in lymphopenia-induced proliferation (LIP). In this study, we show that accumulation of highly divided CD4 T cells characterized by great potential to make IFN-γ is significantly delayed in the absence of B7:CD28 costimulation during LIP. Furthermore, CD28-sufficient CD4 T cells show great competitive advantage over CD28-deficient CD4 T cells when transferred together into the same lymphopenic hosts. Administration of CTLA-4-Ig removed this competitive advantage. Interestingly, CTLA-4-Ig treatment resulted in modest inhibition of LIP by CD28-deficient responders, suggesting that some of its effects may be independent of mere B7 blockade.
Delta-Short Consensus Repeat 4-Decay Accelerating Factor (DAF: CD55) Inhibits Complement-Mediated Cytolysis but Not NK Cell-Mediated Cytolysis
Authors: Miyagawa Shuji , Kubo Tomoko , Matsunami Katsuyoshi , Kusama Tamiko , Beppu Keiko , Nozaki Hiroshi , Moritan Toshiyuki , Ahn Curie , Kim Jae Young , Fukuta Daisuke , Shirakura Ryota 
Published: April 2014

AbstractNK cells play a critical role in the rejection of xenografts. In this study, we report on an investigation of the effect of complement regulatory protein, a decay accelerating factor (DAF: CD55), in particular, on NK cell-mediated cytolysis. Amelioration of human NK cell-mediated pig endothelial cell (PEC) and pig fibroblast cell lyses by various deletion mutants and point substitutions of DAF was tested, and compared with their complement regulatory function. Although wild-type DAF and the delta-short consensus repeat (SCR) 1-DAF showed clear inhibition of both complement-mediated and NK-mediated PEC lyses, delta-SCR2-DAF and delta-SCR3-DAF failed to suppress either process. However, delta-SCR4-DAF showed a clear complement regulatory effect, but had no effect on NK cells. Conversely, the point substitution of DAF (L147·F148 to SS and KKK125–127 to TTT) was half down-regulated in complement inhibitory function, but the inhibition of NK-mediated PEC lysis remained unchanged. Other complement regulatory proteins, such as the cell membrane-bound form factor H, fH-PI, and C1-inactivator, C1-INH-PI, and CD59 were also assessed, but no suppressive effect on NK cell-mediated PEC lysis was found. These data suggest, for DAF to function on NK cells, SCR2–4 is required but no relation to its complement regulatory function exists.
The Binding Sites for Competitive Antagonistic, Allosteric Antagonistic, and Agonistic Antibodies to the I Domain of Integrin LFA-1
Authors: Lu Chafen , Shimaoka Motomu , Salas Azucena , Springer Timothy A. 
Published: April 2014

Abstract
We explore the binding sites for mAbs to the α I domain of the integrin αLβ2 that can competitively inhibit, allosterically inhibit, or activate binding to the ligand ICAM-1. Ten mAbs, some of them clinically important, were mapped to species-specific residues. The results are interpreted with independent structures of the αL I domain determined in seven different crystal lattices and in solution, and which are present in three conformational states that differ in affinity for ligand. Six mAbs bind to adjacent regions of the β1-α1 and α3-α4 loops, which show only small (mean, 0.8 Å; maximum, 1.8 Å) displacements among the eight I domain structures. Proximity to the ligand binding site and to noncontacting portions of the ICAM-1 molecule explains competitive inhibition by these mAbs. Three mAbs bind to a segment of seven residues in the β5-α6 loop and α6 helix, in similar proximity to the ligand binding site, but on the side opposite from the β1-α1/α3-α4 epitopes, and far from noncontacting portions of ICAM-1. These residues show large displacements among the eight structures in response to lattice contacts (mean, 3.6 Å; maximum, 9.4 Å), and movement of a buried Phe in the β5-α6 loop is partially correlated with affinity change at the ligand binding site. Together with a lack of proximity to noncontacting portions of ICAM-1, these observations explain variation among this group of mAbs, which can either act as competitive or allosteric antagonists. One agonistic mAb binds distant from the ligand binding site of the I domain, to residues that show little movement (mean, 0.5 Å; maximum, 1.0 Å). Agonism by this mAb is thus likely to result from altering the orientation of the I domain with respect to other domains within an intact integrin αLβ2 heterodimer.
Characterization of a Dipeptide Motif Regulating IFN-γ Receptor 2 Plasma Membrane Accumulation and IFN-γ Responsiveness
Authors: Rosenzweig Sergio D. , Schwartz Owen M. , Brown Margaret R. , Leto Thomas L. , Holland Steven M. 
Published: April 2014

AbstractThe IFN-γR complex is composed of two IFN-γR1 and two IFN-γR2 polypeptide chains. Although IFN-γR1 is constitutively expressed on all nucleated cells, IFN-γR2 membrane display is selective and tightly regulated. We created a series of fluorescent-tagged IFN-γR2 expression constructs to follow the molecule’s cell surface expression and intracellular distribution. Truncation of the receptor immediately upstream of Leu-Ile 255–256 (254X) created a receptor devoid of signaling that overaccumulated on the cell surface. In addition, this truncated receptor inhibited wild-type IFN-γR2 activity and therefore exerted a dominant negative effect. In-frame deletion (255Δ2) or alanine substitution (LI255–256AA) of these amino acids created mutants that overaccumulated on the plasma membrane, but had enhanced function. Single amino acid substitutions (L255A or I256A) had a more modest effect. In-frame deletions upstream (253Δ2), but not downstream (257Δ2), of Leu-Ile 255–256 also led to overaccumulation. A truncation within the IFN-γR2 Jak2 binding site (270X) led to a mutant devoid of function that did not overaccumulate and did not affect wild-type IFN-γR2 signaling. We have created a series of novel mutants of IFN-γR2 that have facilitated the identification of intracellular domains that control IFN-γR2 accumulation and IFN-γ responsiveness. In contrast to IFN-γR1, not only dominant negative, but also dominant gain-of-function, mutations were created through manipulation of IFN-γR2 Leu-Ile 255–256. These IFN-γR2 mutants will allow fine dissection of the role of IFN-γ signaling in immunity.
Distinct and Opposite Activities of Human Terminal Deoxynucleotidyltransferase Splice Variants
Authors: Thai To-Ha , Kearney John F. 
Published: April 2014

AbstractEvidence for potential human TdT (hTdT) isoforms derived from hTdT genomic sequences led us to identify the short isoform (hTdTS), as well as mature long transcripts containing exon XII (hTdTL1) and another including exon VII (hTdTL2) in lymphoid cells. Normal B and T lymphocytes express exclusively hTdTS and hTdTL2, whereas hTdTL1 expression appears to be restricted to transformed lymphoid cell lines. In in vitro recombination and primer assays, both long isoforms were shown to have 3′→5′ exonuclease activity. Overexpression of hTdTS or hTdTL2 greatly reduced the efficiency of recombination, which was reverted to normal levels by the simultaneous expression of both enzymes. Therefore, alternative splicing may prevent the adverse effects of unchecked elongation or diminution of coding ends during V(D)J recombination, thus affecting the survival of a B or T cell precursor during receptor gene rearrangements. Finally, the newly discovered hTdT isoforms should be considered in future screening of human leukemias.
IL-12p40 and IL-18 Modulate Inflammatory and Immune Responses to Respiratory Syncytial Virus Infection
Authors: Wang Shan-Ze , Bao Yi-Xiao , Rosenberger Cynthia L. , Tesfaigzi Yohannes , Stark James M. , Harrod Kevin S. 
Published: April 2014

Abstract
Respiratory syncytial virus-induced bronchiolitis has been linked to the development of allergy and atopic asthma. IL-12 and possibly IL-18 are central mediators orchestrating Th1 and/or Th2 immune responses to infection. To determine a possible role for IL-12 in regulating the immune response to acute respiratory syncytial virus infection, IL-12p40 gene-targeted (IL-12p40−/−) and wild-type mice were intratracheally infected with respiratory syncytial virus, and lung inflammatory and immune responses were assessed. Lung inflammation and mucus production were increased in the airways of IL-12p40−/− mice as compared with those of wild-type mice, concurrent with increased levels of the Th2 effector cytokines IL-5 and IL-13. Respiratory syncytial virus clearance and levels of Th1 effector cytokine IFN-γ were not altered. Interestingly, IL-18, another mediator of IFN-γ production, was significantly increased in the lungs of IL-12p40−/− mice early during the course of infection. Abrogation of IL-18-mediated signaling in IL-12p40−/− mice further enhanced Th2 immune response and mucus production in the airways during respiratory syncytial virus infection but failed to modulate IFN-γ production or viral clearance. These findings implicate a role for IL-12 and IL-18 in modulating respiratory syncytial virus-induced airway inflammation distinct from that of viral clearance.
Hemozoin (Malarial Pigment) Inhibits Differentiation and Maturation of Human Monocyte-Derived Dendritic Cells: A Peroxisome Proliferator-Activated Receptor-γ-Mediated Effect
Authors: Skorokhod Oleksii A. , Alessio Massimo , Mordmüller Benjamin , Arese Paolo , Schwarzer Evelin 
Published: April 2014

AbstractAcute and chronic Plasmodium falciparum malaria are accompanied by severe immunodepression possibly related to subversion of dendritic cells (DC) functionality. Phagocytosed hemozoin (malarial pigment) was shown to inhibit monocyte functions related to immunity. Hemozoin-loaded monocytes, frequently found in circulation and adherent to endothelia in malaria, may interfere with DC development and play a role in immunodepression. Hemozoin-loaded and unloaded human monocytes were differentiated in vitro to immature DC (iDC) by treatment with GM-CSF and IL-4, and to mature DC (mDC) by LPS challenge. In a second setting, hemozoin was fed to iDC further cultured to give mDC. In both settings, cells ingested large amounts of hemozoin undegraded during DC maturation. Hemozoin-fed monocytes did not apoptose but their differentiation and maturation to DC was severely impaired as shown by blunted expression of MHC class II and costimulatory molecules CD83, CD80, CD54, CD40, CD1a, and lower levels of CD83-specific mRNA in hemozoin-loaded iDC and mDC compared with unfed or latex-loaded DC. Further studies indicated activation of peroxisome proliferator-activated receptor-γ (PPAR-γ) in hemozoin-loaded iDC and mDC, associated with increased expression of PPAR-γ mRNA, without apparent involvement of NF-κB. Moreover, expression of PPAR-γ was induced and up-regulation of CD83 was inhibited by supplementing iDC and mDC with plausible concentrations of 15(S)-hydroxyeicosatetraenoic acid, a PPAR-γ ligand abundantly produced by hemozoin via heme-catalyzed lipoperoxidation.
The Development of Functional CD8 T Cell Memory afterListeria monocytogenesInfection Is Not Dependent on CD40
Authors: Montfort Megan J. , Bouwer H. G. Archie , Wagner Cynthia R. , Hinrichs David J. 
Published: April 2014

AbstractThe immunologic requirements for generating long-lived protective CD8 T cell memory remain unclear. Memory CD8 populations generated in the absence of CD4 Th cells reportedly have functional defects, and at least a subset of CD8 T cells transiently express CD40 after activation, suggesting that direct CD4-CD8 T cell interactions through CD40 may influence the magnitude and functional quality of memory CD8 populations. To ascertain the role of CD40 in such direct T cell interactions, we investigated CD8 T cell responses in CD40−/− mice after infection with Listeria monocytogenes, an intracellular bacterium that induces APC activation and thus priming of CD8 T cells independently of CD4 Th cell help through CD40. In this study we show that memory CD8 T cells generated in CD40-deficient mice show in vivo cytotoxicity and cytokine production equivalent to CD8 memory T cells from wild-type mice. Upon secondary Listeria infection, CD40−/− memory CD8 T cells expand to greater numbers than seen in wild-type mice. These results indicate that CD40 ligation on CD8 T cells, although reportedly a part of CD8 T cell memory development in an H-Y-directed response, is not needed for the development of functional memory CD8 T cell populations after Listeria infection.
Platelet-Derived Thrombospondin-1 Is Necessary for the Vitamin D-Binding Protein (Gc-Globulin) to Function as a Chemotactic Cofactor for C5a
Authors: Trujillo Glenda , Kew Richard R. 
Published: April 2014

AbstractThe chemotactic activity of C5a and C5a des Arg can be enhanced significantly by the vitamin D-binding protein (DBP), also known as Gc-globulin. DBP is a multifunctional 56-kDa plasma protein that binds and transports several diverse ligands. The objective of this study was to investigate the mechanisms by which DBP functions as a chemotactic cofactor for C5a using neutrophils and U937 cells transfected with the C5aR (U937-C5aR cells). The results demonstrate that U937-C5aR cells show C5a chemotactic enhancement only to DBP in serum, but, unlike mature neutrophils, this cell line cannot respond to DBP in plasma or to purified DBP. Analysis by SDS-PAGE and isoelectric focusing revealed no structural difference between DBP in serum compared with DBP in plasma. However, plasma supplemented with either serum, DBP-depleted serum, or activated platelet releasate provides a required factor and permits DBP to function as a chemotactic cofactor for C5a. Fractionation of activated platelet releasate revealed that the additional factor possessed the properties of thrombospondin-1 (TSP-1). Finally, purified TSP-1 alone could reproduce the effect of serum or platelet releasate, whereas Abs to TSP-1 could block these effects. These results provide clear evidence that TSP-1 is needed for DBP to function as a chemotactic cofactor for C5a.
Cigarette Smoke Inhibits Lipopolysaccharide-Induced Production of Inflammatory Cytokines by Suppressing the Activation of Activator Protein-1 in Bronchial Epithelial Cells
Authors: Laan Martti , Bozinovski Steven , Anderson Gary P. 
Published: April 2014

AbstractChronic smoking is characterized by immunosuppressive changes in the airways, leading to chronic colonization with bacteria, which in turn may contribute to the chronic obstructive pulmonary disease. The mechanisms causing this immunosuppression, however, are poorly characterized. This study evaluated whether cigarette smoke can inhibit endotoxin (LPS)-induced inflammatory cytokine production in bronchial epithelial cells and, if so, what the mechanisms are behind this effect. Pretreatment with cigarette smoke extract (CSE) concentration dependently inhibited the LPS-induced GM-CSF and IL-8 protein release, which was accompanied by decreased expression of mRNA in human bronchial epithelial cells (Beas-2B). The increase of neutrophil chemotaxis induced by conditioned medium from LPS-treated Beas-2B cells was also suppressed by CSE. In addition, the activity of LPS-induced transcription factor AP-1, but not NF-κB, was down-regulated by CSE. Notably, at the concentrations used, CSE had no effect on number or viability of Beas-2B cells. These data indicate that cigarette smoke possesses immunosuppressive properties by down-regulating the bacterial pathogen-induced neutrophil-mobilizing cytokine production via suppression of AP-1 activation in the airways. Hence, this study suggests a novel mechanism by which cigarette smoke may contribute to chronic colonization and chronic obstructive pulmonary disease in smokers.
Modulation of Renal Disease in MRL/lpr Mice by Suberoylanilide Hydroxamic Acid
Authors: Reilly Christopher M. , Mishra Nilamadhab , Miller Julie M. , Joshi Dimple , Ruiz Phillip , Richon Victoria M. , Marks Paul A. , Gilkeson Gary S. 
Published: April 2014

Abstract
Epigenetic regulation of gene expression is involved in the development of many diseases. Histone acetylation is a posttranslational modification of the nucleosomal histone tails that is regulated by the balance of histone deacetylases and histone acetyltransferases. Alterations in the balance of histone acetylation have been shown to cause aberrant expression of genes that are a hallmark of many diseases, including systemic lupus erythematosus. In this study, we determined whether suberoylanilide hydroxamic acid (SAHA), a histone deacetylase inhibitor: 1) inhibits inflammatory mediator production in vitro and 2) modulates lupus progression in vivo. Mesangial cells isolated from 10-wk-old MRL/lpr mice were stimulated with LPS/IFN-γ and incubated with SAHA. TNF-α, IL-6, NO, and inducible NO synthase expression were inhibited by SAHA. We then treated MRL/lpr mice with daily injections of SAHA from age 10 to 20 wk. The animals treated with SAHA had decreased spleen size and a concomitant decrease in CD4−CD8− (double-negative) T cells compared with controls. Serum autoantibody levels and glomerular IgG and C3 deposition in SAHA-treated mice were similar to controls. In contrast, proteinuria and pathologic renal disease were significantly inhibited in the mice receiving SAHA. These data indicate that SAHA blocks mesangial cell inflammatory mediator production in vitro and disease progression in vivo in MRL/lpr mice.
Proinflammatory Cytokines Induce Proteinase 3 as Membrane-Bound and Secretory Forms in Human Oral Epithelial Cells and Antibodies to Proteinase 3 Activate the Cells through Protease-Activated Receptor-2
Authors: Uehara Akiko , Sugawara Yumiko , Sasano Takashi , Takada Haruhiko , Sugawara Shunji 
Published: April 2014

Abstract
Anti-neutrophil cytoplasmic Abs targeting proteinase 3 (PR3) have been detected in relation to a wide range of inflammatory conditions such as periodontitis, and interaction of anti-PR3 Abs with endothelial and epithelial cells provokes cell activation, although the underlying mechanism has been unclear. The present study showed that human oral epithelial cells expressed PR3 mRNA after treatment with proinflammatory cytokines such as IL-1α, TNF-α, IFN-α, IFN-β, and IFN-γ. A 29-kDa PR3 was expressed on the cell surface and released into culture supernatants by the cells upon stimulation with these cytokines. The membrane and supernatant fractions of oral epithelial cells exhibited enzymatic activity, which was inhibited by serine proteinase inhibitors, but not by a cysteine proteinase inhibitor or secretory leukocyte protease inhibitor. Addition of anti-PR3 Abs to cytokine-primed oral epithelial cells in culture induced remarkable secretion of IL-8 and monocyte chemoattractant protein 1 and aggregation of PR3 on the cells. RNA interference targeted to protease-activated receptor-2 mRNA and intracellular Ca2+ mobilization assays revealed that anti-PR3 Abs activated the epithelial cells through protease-activated receptor-2, a family of G protein-coupled receptors. The anti-PR3 Ab-mediated cell activation was completely abolished by RNA interference targeted to PR3 mRNA and by inhibition of phospholipase C and NF-κB. Immunohistochemistry showed that inflamed oral epithelium actually expresses PR3 protein. These results suggest that oral epithelial cells express functional PR3 in the inflamed sites and respond to anti-PR3 Abs detected in diseased sera, and that these mechanisms may actively participate in the inflammatory process, including periodontitis.
Renal Expression of the C3a Receptor and Functional Responses of Primary Human Proximal Tubular Epithelial Cells
Authors: Braun Michael C. , Reins Rose Y. , Li Tong-bin , Hollmann Travis J. , Dutta Ranjan , Rick Wetsel A. , Teng Ba-Bie , Ke Baozhen 
Published: April 2014

Abstract
Although complement activation and deposition have been associated with a variety of glomerulopathies, the pathogenic mechanisms by which complement directly mediates renal injury remain to be fully elucidated. Renal parenchymal tissues express a limited repertoire of receptors that directly bind activated complement proteins. We report the renal expression of the receptor for the C3 cleavage product C3a, a member of the anaphylatoxin family. C3aR is highly expressed in normal human and murine kidney, as demonstrated by immunohistochemistry and in situ hybridization. Its distribution is limited to epithelial cells only, as glomerular endothelial and mesangial cells showed no evidence of C3aR expression. The C3aR is also expressed by primary renal proximal tubular epithelial cells in vitro as demonstrated by FACS, Western blot, and RT-PCR. In vitro C3aR is functional in terms of its capacity to bind 125I-labeled C3a and generate inositol triphosphate. Finally, using microarray analysis, four novel genes were identified and confirmed as transcriptionally regulated by C3aR activation in proximal tubular cells. These studies define a new pathway by which complement activation may directly modulate the renal response to immunologic injury.