bluuebunny/crossref_metadata_2025_split huggingface dataset:
Immune Evasion of Enterococcus faecalis by an Extracellular Gelatinase That Cleaves C3 and iC3b
Authors: Park Shin Yong , Shin Yong Pyo , Kim Chong Han , Park Ho Jin , Seong Yeon Sun , Kim Byung Sam , Seo Sook Jae , Lee In Hee 
Published: April 2014

Abstract
Enterococcus faecalis (Ef) accounts for most cases of enterococcal bacteremia, which is one of the principal causes of nosocomial bloodstream infections (BSI). Among several virulence factors associated with the pathogenesis of Ef, an extracellular gelatinase (GelE) has been known to be the most common factor, although its virulence mechanisms, especially in association with human BSI, have yet to be demonstrated. In this study, we describe the complement resistance mechanism of Ef mediated by GelE. Using purified GelE, we determined that it cleaved the C3 occurring in human serum into a C3b-like molecule, which was inactivated rapidly via reaction with water. This C3 convertase-like activity of GelE was shown to result in a consumption of C3 and thus inhibited the activation of the complement system. Also, GelE was confirmed to degrade an iC3b that was deposited on the Ag surfaces without affecting the bound C3b. This proteolytic effect of GelE against the major complement opsonin resulted in a substantial reduction in Ef phagocytosis by human polymorphonuclear leukocytes. In addition, we verified that the action of GelE against C3, which is a central component of the complement cascade, was human specific. Taken together, it was suggested that GelE may represent a promising molecule for targeting human BSI associated with Ef.
Activation of Antigen-Specific Cytotoxic T Lymphocytes by β2-Microglobulin or TAP1 Gene Disruption and the Introduction of Recipient-Matched MHC Class I Gene in Allogeneic Embryonic Stem Cell-Derived Dendritic Cells
Authors: Matsunaga Yusuke , Fukuma Daiki , Hirata Shinya , Fukushima Satoshi , Haruta Miwa , Ikeda Tokunori , Negishi Izumi , Nishimura Yasuharu , Senju Satoru 
Published: April 2014

Abstract
A method for the genetic modification of dendritic cells (DC) was previously established based on the in vitro differentiation of embryonic stem (ES) cells to DC (ES-DC). The unavailability of human ES cells genetically identical to the patients will be a problem in the future clinical application of this technology. This study attempted to establish a strategy to overcome this issue. The TAP1 or β2-microglobulin (β2m) gene was disrupted in 129 (H-2b)-derived ES cells and then expression vectors for the H-2Kd or β2m-linked form of Kd (β2m-Kd) were introduced, thus resulting in two types of genetically engineered ES-DC, TAP1−/−/Kd ES-DC and β2m−/−/β2m-Kd ES-DC. As intended, both of the transfectant ES-DC expressed Kd but not the intrinsic H-2b haplotype-derived MHC class I. β2m−/−/β2m-Kd and TAP1−/−/Kd ES-DC were not recognized by pre-activated H-2b-reactive CTL and did not prime H-2b reactive CTL in vitro or in vivo. β2m−/−/β2m-Kd ES-DC and TAP1−/−/Kd ES-DC had a survival advantage in comparison to β2m+/−/β2m-Kd ES-DC and TAP1+/+/Kd ES-DC, when transferred into BALB/c mice. Kd-restricted RSV-M2-derived peptide-loaded ES-DC could prime the epitope-specific CTL upon injection into the BALB/c mice, irrespective of the cell surface expression of intrinsic H-2b haplotype-encoded MHC class I. β2m−/−/β2m-Kd ES-DC were significantly more efficient in eliciting immunity against RSV M2 protein-expressing tumor cells than β2m+/−/β2m-Kd ES-DC. The modification of the β2m or TAP gene may therefore be an effective strategy to resolve the problem of HLA class I allele mismatch between human ES or induced pluripotent stem cells and the recipients to be treated.
CD28 Signaling in T Regulatory Precursors Requires p56lck and Rafts Integrity to Stabilize the Foxp3 Message
Authors: Nazarov-Stoica Cristina , Surls Jacqueline , Bona Constantin , Casares Sofia , Brumeanu Teodor-D. 
Published: April 2014

Abstract
Naturally occurring CD4+25highFoxp3+ T regulatory (T-reg) cells are critical for maintaining tolerance to self and non-self Ags. The Foxp3 master-regulatory gene and CD28 costimulation are both required for thymic development and suppressogenic function of CD4+25highFoxp3+ T-regs. Herein, we show that the sole CD28 stimulation of T-reg thymic precursors augments Foxp3 expression through the increase in Foxp3 mRNA span life by a mechanism involving p56lck and its binding motif on CD28 cytosolic tail, as well as the lipid rafts. We found that 1) the glycosphingolipids and cholesterol components of lipid rafts were highly expressed and unusually partitioned in T-reg thymic precursors as compared with the conventional T cell precursors, 2) the CD28 receptor density on cell membrane is proportional with the content of cholesterol in lipid rafts and with the level of Foxp3 mRNA expression in T-reg precursors, and 3) the CD28-mediated increase of Foxp3 mRNA span life was paralleled by an increased proliferative and suppressogenic capacity of terminally differentiated CD4+25highFoxp3+ T-reg precursors. Thus, the functional integrity of CD28 receptor p56lck and plasma membrane lipid rafts are all prerequisites for up-regulation and long-term expression of Foxp3 mRNA transcripts in CD4+25highFoxp3+ T-reg precursors.
Contribution of Direct and Cross-Presentation to CTL Immunity against Herpes Simplex Virus 1
Authors: Jirmo Adan Chari , Nagel Claus-Henning , Bohnen Christof , Sodeik Beate , Behrens Georg M. N. 
Published: April 2014

AbstractDendritic cells (DC), which can be subdivided into different phenotypic and functional subsets, play a pivotal role in the generation of cytotoxic T cell immunity against viral infections. Understanding the modes of Ag acquisition, processing and presentation by DC is essential for the design of effective antiviral vaccines. We aimed to assess the contribution of direct vs cross-presentation for the induction of HSV1-specific CD8+ T lymphocyte responses in mice. Using HSV1 strains expressing fluorescence proteins, we provide evidence for the ability of HSV1 to induce viral transcription. Using HSV1-wild-type as well as gB- or gH-deficient mutants to either directly inoculate DC or to infect target cells, which then were given to DC, we show that DC acquired viral Ag via phagocytosis of target cells and via direct inoculation of virus being released from target cells. Our study corroborates the function of the CD8+ DC specialized in Ag cross-presentation and confirms this specific feature for Ags that these DC acquire directly from HSV1. However, although infection of cross-presenting DC amplified T cell responses, it was not a requirement for presentation of viral Ags, both in vitro and in vivo. Finally, we provide evidence that direct presentation did not contribute to the Ag presentation capacity of CD8+ DC after phagocytosis of infected target cells. We conclude that cross-presentation is of major importance for the induction of CTL immunity in mice.
Genome-Wide Innate Immune Responses in HIV-1-Infected Macrophages Are Preserved Despite Attenuation of the NF-κB Activation Pathway
Authors: Noursadeghi Mahdad , Tsang Jhen , Miller Robert F. , Straschewski Sarah , Kellam Paul , Chain Benjamin M. , Katz David R. 
Published: April 2014

Abstract
Macrophages contribute to HIV-1 infection at many levels. They provide permissive cells at the site of inoculation, augment virus transfer to T cells, generate long-lived viral reservoirs, and cause bystander cell apoptosis. A body of evidence suggests that the role of macrophages in cellular host defense is also compromised by HIV-1 infection. In this respect, macrophages are potent cells of the innate immune system that initiate and regulate wide-ranging immunological responses. This study focuses on the effect of HIV-1 infection on innate immune responses by macrophages at the level of signal transduction, whole genome transcriptional profiling, and cytokine secretion. We show that in an ex vivo model, M-CSF-differentiated monocyte-derived macrophages uniformly infected with replicating CCR5-tropic HIV-1, without cytopathic effect, exhibit selective attenuation of the NF-κB activation pathway in response to TLR4 and TLR2 stimulation. However, functional annotation clustering analysis of genome-wide transcriptional responses to LPS stimulation suggests substantial preservation of gene expression changes at the systems level, with modest attenuation of a subset of up-regulated LPS-responsive genes, and no effect on a selection of inflammatory cytokine responses at the protein level. These results extend existing reports of inhibitory interactions between HIV-1 accessory proteins and NF-κB signaling pathways, and whole genome expression profiling provides comprehensive assessment of the consequent effects on immune response gene expression. Unexpectedly, our data suggest innate immune responses are broadly preserved with limited exceptions, and pave the way for further study of the complex relationship between HIV-1 and immunological pathways within macrophages.
Presentation of Cytosolically Stable Peptides by HLA-B27 Is Not Dependent on the Canonic Interactions of N-Terminal Basic Residues in the A Pocket
Authors: Gómez Patricia , Mavian Carla , Galocha Begoña , García-Medel Noel , López de Castro José A. 
Published: April 2014

Abstract
HLA-B27 binds peptides with R at position 2. Additionally, a substantial fraction of the HLA-B27-bound peptide repertoire has basic residues at position 1. It is unclear whether this is determined by structural complementarity with the A pocket of the peptide-binding site, by the increased availability of peptides with dibasic N-terminal sequences resulting from their cytosolic stability, or both. To distinguish between these possibilities two B*2705 mutants were generated in which one or two A pocket surface residues stabilizing the peptidic R1 side chain were changed: E163T and E163T-W167S. Both mutants bound a large fraction of the constitutive peptide repertoire of B*2705. Moreover, 90 B*2705 ligands of known sequence were examined for their endogenous presentation by the mutants. The E163T mutation alone had a limited effect on binding of peptides with R1 or K1 and on the relative frequencies of N-terminal residues. However, it decreased the overall stability of the molecule. The E163T-W167S mutant also bound many of the B*2705 ligands with N-terminal basic residues, but its preference for G1 was significantly decreased. The results indicate that the capacity of HLA-B27 to bind peptides with N-terminal basic residues is largely independent of the canonic interactions that stabilize at least the R1 side chain. Thus, the prevalence of HLA-B27 ligands with dibasic N-terminal sequences may be significantly influenced by the increased availability of these peptides resulting from their cytosolic stability. This confers to HLA-B27 a unique capacity to present Ags generated in low amounts, but resistant to intracellular degradation.
Residue Lys57 in the Collagen-Like Region of Human L-Ficolin and Its Counterpart Lys47 in H-Ficolin Play a Key Role in the Interaction with the Mannan-Binding Lectin-Associated Serine Proteases and the Collectin Receptor Calreticulin
Authors: Lacroix Monique , Dumestre-Pérard Chantal , Schoehn Guy , Houen Gunnar , Cesbron Jean-Yves , Arlaud Gérard J. , Thielens Nicole M. 
Published: April 2014

Abstract
L- and H-ficolins are serum oligomeric defense proteins consisting of a collagen-like region and a fibrinogen-like recognition domain that bind to pathogen- and apoptotic cell-associated molecular patterns. They share with mannan-binding lectin (MBL) the ability to associate with MBL-associated serine proteases (MASP)-1, -2, -3, and protein MAp19 and to trigger the lectin complement pathway through MASP-2 activation. Recent studies have revealed the essential role of Lys55 in the collagenous region of MBL in the interaction with the MASPs and calreticulin (CRT). To test the possible involvement of the homologous residues Lys57 of L-ficolin and Lys47 of H-ficolin, point mutants of both proteins were produced in which these residues were mutated to Ala, Glu, or Arg. The resulting mutants exhibited oligomerization patterns and ligand binding properties similar to those of their wild-type counterparts. In contrast, all three mutations strongly inhibited the interaction of L- and H-ficolins with MAp19 and MASP-2 and impaired the ability of each ficolin to trigger the lectin pathway. In the case of MASP-1 and MASP-3, replacement of the target Lys residues by Ala or Glu abolished interaction, whereas the Lys to Arg mutations had only slight inhibitory effects. Likewise, binding of each ficolin to CRT was inhibited by mutation of Lys to Ala or Glu, but not to Arg. In conclusion, residues Lys57 of L-ficolin and Lys47 of H-ficolin are key components of the interaction with the MASPs and CRT, providing strong indication that MBL and the ficolins share homologous binding sites for both types of proteins.
CHAC1/MGC4504 Is a Novel Proapoptotic Component of the Unfolded Protein Response, Downstream of the ATF4-ATF3-CHOP Cascade
Authors: Mungrue Imran N. , Pagnon Joanne , Kohannim Omid , Gargalovic Peter S. , Lusis Aldons J. 
Published: April 2014

Abstract
To understand pathways mediating the inflammatory responses of human aortic endothelial cells to oxidized phospholipids, we previously used a combination of genetics and genomics to model a coexpression network encompassing &gt;1000 genes. CHAC1 (cation transport regulator-like protein 1), a novel gene regulated by ox-PAPC (oxidized 1-palmitoyl-2-arachidonyl-sn-3-glycero-phosphorylcholine), was identified in a co-regulated group of genes enriched for components of the ATF4 (activating transcription factor 4) arm of the unfolded protein response pathway. Herein, we characterize the role of CHAC1 and validate the network model. We first define the activation of CHAC1 mRNA by chemical unfolded protein response-inducers, but not other cell stressors. We then define activation of CHAC1 by the ATF4-ATF3-CHOP (C/EBP homologous protein), and not parallel XBP1 (X box-binding protein 1) or ATF6 pathways, using siRNA and/or overexpression plasmids. To examine the subset of genes downstream of CHAC1, we used expression microarray analysis to identify a list of 227 differentially regulated genes. We validated the activation of TNFRSF6B (tumor necrosis factor receptor superfamily, member 6b), a FASL decoy receptor, in cells treated with CHAC1 small interfering RNA. Finally, we showed that CHAC1 overexpression enhanced apoptosis, while CHAC1 small interfering RNA suppressed apoptosis, as determined by TUNEL, PARP (poly(ADP-ribose) polymerase) cleavage, and AIF (apoptosis-inducing factor) nuclear translocation.
Cutting Edge: The Metalloproteinase ADAM17/TNF-α-Converting Enzyme Regulates Proteolytic Shedding of the MHC Class I-Related Chain B Protein
Authors: Boutet Philippe , Agüera-González Sonia , Atkinson Susan , Pennington Caroline J. , Edwards Dylan R. , Murphy Gillian , Reyburn Hugh T. , Valés-Gómez Mar 
Published: April 2014

Abstract
MHC class I-related chain (MIC) A/B are transmembrane proteins expressed in pathological conditions that are ligands for the activating receptor NKG2D found on cytotoxic lymphocytes. Soluble NKG2D ligands are detected in sera of patients suffering from multiple types of cancer where they are associated with reduced levels of receptor expression and compromised function of NK and CTLs. In this study, we report the identification of a metalloproteinase involved in the cleavage process of MIC; inhibition and knockdown of ADAM17/TACE blocks the shedding of these proteins. Strikingly, the recruitment of both enzyme and substrate to detergent-resistant membrane microdomains is crucial for efficient proteolysis. These findings provide a novel insight into the molecular mechanisms of MIC shedding.
Milk Fat Globule Epidermal Growth Factor-Factor VIII Is Down-Regulated in Sepsis via the Lipopolysaccharide-CD14 Pathway
Authors: Komura Hidefumi , Miksa Michael , Wu Rongqian , Goyert Sanna M. , Wang Ping 
Published: April 2014

Abstract
Phagocytosis prevents the release of potentially harmful or immunogenic materials from dying cells. Milk fat globule epidermal growth factor (EGF)-factor VIII (MFG-E8) mediates the clearance of apoptotic cells. We have previously shown that the administration of MFG-E8-rich exosomes from immature dendritic cells promotes the phagocytosis of apoptotic cells and improves survival in sepsis. Because endotoxin is elevated in polymicrobial sepsis, we hypothesized that down-regulation of MFG-E8 is mediated via the LPS-CD14 pathway, eventually leading to the accruement of apoptotic cells. Polymicrobial sepsis was induced by cecal ligation and puncture (CLP) in CD14-deficient (CD14−/−), TLR4-mutated and wild-type (WT) mice. In addition, endotoxemia was elicited by i.p. injection of LPS. LPS was also neutralized by pretreating CLP-induced WT mice with polymyxin B. Splenic MFG-E8 expression, phagocytic activity, and apoptosis were assessed 5 and 20 h after CLP or 5 h after LPS administration. In septic WT mice, MFG-E8 mRNA and protein levels were suppressed by 49 and 33%, respectively. Endotoxemia reduced MFG-E8 mRNA expression in a dose dependent manner and the down-regulation of MFG-E8 mRNA expression in CLP-induced sepsis was attenuated by polymyxin B. This CLP-induced suppression was not observed in both CD14−/− and TLR4-mutated mice. CLP significantly decreased phagocytic activity of peritoneal macrophages in WT (by 30%), but not in CD14−/− mice. CLP also induced significant apoptosis in the spleen of WT (by 61%), but less in CD14−/− mice. Thus, MFG-E8 production is down-regulated in sepsis by LPS-CD14 dependent fashion, leading to a reduction of phagocytosis of apoptotic cells.
Potential Roles of a Special CD8αα+ Cell Population and CC Chemokine Thymus-Expressed Chemokine in Ovulation Related Inflammation
Authors: Zhou Cindy , Wu Jean , Borillo Jason , Torres Lisa , McMahon John , Lou Ya-Huan 
Published: April 2014

Abstract
It is well known that ovulation may be an inflammatory process. However, it remains elusive how immune cells participate in this process. We have identified a novel CD8αα+ population, which resembles tissue dendritic cells, in the theca of antral follicles. We further observed a dramatic influx of the CD8αα+cells into the ovulating follicles. This CD8αα+population was absent in the ovary of estradiol-induced anovulatory C31F1 mice and subfertile athymic nude mice. Expression of a CC chemokine thymus-expressed chemokine (TECK) has previously been found in the ovary; we further demonstrated that TECK attracted CD8αα+cells into the ovary. Anti-TECK Ab, elicited in the female mice by active immunization, depleted the ovarian CD8αα+ cells in vivo. Mice with a high titer of TECK Ab failed to ovulate after superovulation induction. More importantly, the immunized mice had greatly reduced fertility, which was positively correlated with the Ab titers. Ovarian TECK expression was normal in anovulatory C31F1 mice, suggesting that infertility in the immunized mice is due to a block of CD8αα+ cell migration. Finally, the origin of ovarian CD8αα+ cells was explored. Upon being transferred, thymic CD8α+ cells were able to home to the theca of follicles in the recipients. Thus, ovarian CD8αα+ cells, which participate in the ovulation-related inflammation, may originate in the thymus.
CD11b+ Myeloid Cells Are the Key Mediators of Th2 Cell Homing into the Airway in Allergic Inflammation
Authors: Medoff Benjamin D. , Seung Edward , Hong Sandra , Thomas Seddon Y. , Sandall Barry P. , Duffield Jeremy S. , Kuperman Douglas A. , Erle David J. , Luster Andrew D. 
Published: April 2014

Abstract
STAT6-mediated chemokine production in the lung is required for Th2 lymphocyte and eosinophil homing into the airways in allergic pulmonary inflammation, and thus is a potential therapeutic target in asthma. However, the critical cellular source of STAT6-mediated chemokine production has not been defined. In this study, we demonstrate that STAT6 in bone marrow-derived myeloid cells was sufficient for the production of CCL17, CCL22, CCL11, and CCL24 and for Th2 lymphocyte and eosinophil recruitment into the allergic airway. In contrast, STAT6 in airway-lining cells did not mediate chemokine production or support cellular recruitment. Selective depletion of CD11b+ myeloid cells in the lung identified these cells as the critical cellular source for the chemokines CCL17 and CCL22. These data reveal that CD11b+ myeloid cells in the lung help orchestrate the adaptive immune response in asthma, in part, through the production of STAT6-inducible chemokines and the recruitment of Th2 lymphocytes into the airway.
Th17-Polarized Immune Response in a Murine Model of Hypersensitivity Pneumonitis and Lung Fibrosis
Authors: Simonian Philip L. , Roark Christina L. , Wehrmann Fabian , Lanham Allison K. , Diaz del Valle Fernando , Born Willi K. , O’Brien Rebecca L. , Fontenot Andrew P. 
Published: April 2014

Abstract
Hypersensitivity pneumonitis is an environmental lung disease characterized by a diffuse mononuclear cell infiltrate in the lung that can progress to pulmonary fibrosis with chronic exposure to an inhaled Ag. Using a well-established murine model of hypersensitivity pneumonitis, we repeatedly exposed C57BL/6 mice to Saccharopolyspora rectivirgula to investigate whether T cells are required for lung fibrosis. In the absence of αβ T cells, TCRβ−/− mice exposed to S. rectivirgula for 4 wk had markedly decreased mononuclear infiltrates and collagen deposition in the lung compared with wild-type C57BL/6 mice. In contrast to CD8+ T cells, adoptive transfer of CD4+ T cells reconstituted the S. rectivirgula-induced inflammatory and fibrotic response, suggesting that the CD4+ T cell represents the critical αβ T cell subset. Cytokine analysis of lung homogenates at various time points after S. rectivirgula exposure failed to identify a predominant Th1 or Th2 phenotype. Conversely, IL-17 was found in the lung at increasing concentrations with continued exposure to S. rectivirgula. Intracellular cytokine staining revealed that 14% of CD4+ T cells from the lung of mice treated with S. rectivirgula expressed IL-17A. In the absence of IL-17 receptor signaling, Il17ra−/− mice had significantly decreased lung inflammation and fibrosis compared with wild-type C57BL/6 mice. These data are the first to demonstrate an important role for Th17-polarized CD4+ T lymphocytes in the immune response directed against S. rectivirgula in this murine model of hypersensitivity pneumonitis and pulmonary fibrosis.
JNK MAPK Pathway Regulates Constitutive Transcription of CCL5 by Human NK Cells through SP1
Authors: Kumar Dilip , Hosse Judith , von Toerne Christine , Noessner Elfriede , Nelson Peter J. 
Published: April 2014

Abstract
The MAPKs ERK, JNK, and p38 control diverse aspects of the immune response, including regulation of cytotoxin biology in NK cells and CTL. The chemokine CCL5 is coreleased with the cytotoxins, perforin, the granzymes, and granulysin, during the lethal hit administered by cytotoxic CD8+ T cells (CTL). CCL5 expression is up-regulated relatively late in CTL coincident with their functional maturation 3–7 days after activation. Unlike T cells, NK cells have the ability to kill virally infected or transformed cells when directly isolated from the peripheral circulation. In this study, we show that in contrast to T cells, peripheral blood NK cells express CCL5 constitutively. The use of specific inhibitors of the JNK, ERK, and p38 MAPK pathways showed that the JNK pathway controls expression of CCL5 by NK cells. Promoter-reporter assays identified a compact region of the CCL5 promoter responsible for the constitutive transcription of CCL5 by NK cells. EMSA, chromatin immune precipitation, the use of heterologous promoters, and site-directed mutagenesis demonstrated that transcription in NK cells is largely controlled through binding of the transcription factor specificity protein 1 to a region −75 to −56 upstream of the site of transcriptional initiation. Specificity protein 1 expression, and in turn the constitutive expression of CCL5, was found to be controlled through constitutive activation of the JNK/MAPK pathway in peripheral blood NK cells.