bluuebunny/crossref_metadata_2025_split huggingface dataset:
Decreased Neutrophil Adhesion to Human Cytomegalovirus-Infected Retinal Pigment Epithelial Cells Is Mediated by Virus-Induced Up-Regulation of Fas Ligand Independent of Neutrophil Apoptosis
Authors: Cinatl Jindrich , Blaheta Roman , Bittoova Martina , Scholz Martin , Margraf Stefan , Vogel Jens-Uwe , Cinatl Jaroslav , Doerr Hans Wilhelm 
Published: April 2014

AbstractHuman CMV (HCMV) retinitis frequently leads to blindness in iatrogenically immunosuppressed patients and in the end stage of AIDS. Despite the general proinflammatory potential of HCMV, virus infection is associated with a rather mild cellular inflammatory response in the retina. To investigate this phenomenon, the influence of HCMV (strains AD169 or Hi91) infection on C-X-C chemokine secretion, ICAM-1 expression, and neutrophil recruitment in cultured human retinal pigment epithelial (RPE) cells was studied. Supernatants from infected cultures contained enhanced levels of IL-8 and melanoma growth-stimulating activity/Gro α and induced neutrophil chemotaxis compared with supernatants from uninfected RPE cells. Despite HCMV-induced ICAM-1 expression on RPE cells, binding of activated neutrophils to HCMV-infected RPE cells and subsequent transepithelial penetration were significantly reduced. Reduced neutrophil adhesion to infected RPE cells correlated with HCMV-induced up-regulation of constitutive Fas ligand (FasL) expression. Functional blocking of FasL on RPE cells with the neutralizing mAbs NOK-1 and NOK-2 or of the Fas receptor on neutrophils with mAbB-D29 prevented the HCMV-induced impairment of neutrophil/RPE interactions. Fas-FasL-dependent impairment of neutrophil binding had occurred by 10 min after neutrophil/RPE coculture without apoptotic signs. Neutrophil apoptosis was first detected after 4 h. Treatment of neutrophils with a specific inhibitor of caspase-8 suppressed apoptosis, whereas it did not prevent impaired neutrophil binding to infected RPE. The current results suggest a novel role for FasL in the RPE regulation of neutrophil binding. This may be an important feature of virus escape mechanisms and for sustaining the immune-privileged character of the retina during HCMV ocular infection.
Cell-Specific Expression of the Murine CD21 Gene Depends on Accessibility of Promoter and Intronic Elements
Authors: Zabel Mark D. , Byrne Burke L. , Weis Janis J. , Weis John H. 
Published: April 2014

AbstractThe murine complement receptor type 2 gene (Cr2/CD21) is transcriptionally active in murine B and follicular dendritic cells, but not in murine T cells. We have previously shown that altering chromatin structure via histone deacetylase inhibitors results in CD21 expression in murine T cells, and that the minimal CD21 promoter provided appropriate cell-specific expression of luciferase reporter constructs only in the presence of the first third of intron 1, fragment A. We extend this work by showing that replacing the CD21 gene promoter with the SV40 promoter resulted in the loss of this cell-specific control. Further delineation of intronic regulatory elements by fragmentation also resulted in the loss of cell-specific gene expression, suggesting that multiple CD21 promoter and intronic elements interact for appropriate CD21 gene expression. To assess this model, we performed EMSAs to define protein binding sites within promoter and intronic regions and DNase I hypersensitivity assays to determine chromatin accessibility. Multiple DNA binding factors were shown to be present in B and T cell extracts; a minority demonstrated B cell specificity. However, the DNase I sensitivity of T cell CD21 regulatory elements was not comparable to that of B cells until the histone acetylation status of the gene was altered. Taken together, these data suggest that chromatin remodeling facilitates cell-specific CD21 gene expression by modulating access of transcription factors to regulatory elements in the promoter and intron.
Mutational Analysis Reveals Multiple Distinct Sites Within Fcγ Receptor IIB That Function in Inhibitory Signaling
Authors: Fong Dana C. , Brauweiler Anne , Minskoff Stacy A. , Bruhns Pierre , Tamir Idan , Mellman Ira , Daeron Marc , Cambier John C. 
Published: April 2014

AbstractThe low-affinity receptor for IgG, FcγRIIB, functions broadly in the immune system, blocking mast cell degranulation, dampening the humoral immune response, and reducing the risk of autoimmunity. Previous studies concluded that inhibitory signal transduction by FcγRIIB is mediated solely by its immunoreceptor tyrosine-based inhibition motif (ITIM) that, when phosphorylated, recruits the SH2-containing inositol 5′- phosphatase SHIP and the SH2-containing tyrosine phosphatases SHP-1 and SHP-2. The mutational analysis reported here reveals that the receptor’s C-terminal 16 residues are also required for detectable FcγRIIB association with SHIP in vivo and for FcγRIIB-mediated phosphatidylinositol 3-kinase hydrolysis by SHIP. Although the ITIM appears to contain all the structural information required for receptor-mediated tyrosine phosphorylation of SHIP, phosphorylation is enhanced when the C-terminal sequence is present. Additionally, FcγRIIB-mediated dephosphorylation of CD19 is independent of the cytoplasmic tail distal from residue 237, including the ITIM. Finally, the findings indicate that tyrosines 290, 309, and 326 are all sites of significant FcγRIIB1 phosphorylation following coaggregation with B cell Ag receptor. Thus, we conclude that multiple sites in FcγRIIB contribute uniquely to transduction of FcγRIIB-mediated inhibitory signals.
Regulated Production and Molecular Diversity of Human Liver and Activation-Regulated Chemokine/Macrophage Inflammatory Protein-3α from Normal and Transformed Cells
Authors: Schutyser Evemie , Struyf Sofie , Menten Patricia , Lenaerts Jean-Pierre , Conings René , Put Willy , Wuyts Anja , Proost Paul , Van Damme Jo 
Published: April 2014

AbstractLiver and activation-regulated chemokine (LARC), also designated macrophage inflammatory protein-3α (MIP-3α), Exodus, or CCL20, is a C-C chemokine that attracts immature dendritic cells and memory T lymphocytes, both expressing CCR6. Depending on the cell type, this chemokine was found to be inducible by cytokines (IL-1β) and by bacterial, viral, or plant products (including LPS, dsRNA, and PMA) as measured by a specific ELISA. Although coinduced with monocyte chemotactic protein-1 (MCP-1) and IL-8 by dsRNA, measles virus, and IL-1β in diploid fibroblasts, leukocytes produced LARC/MIP-3α only in response to LPS. However, in myelomonocytic THP-1 cells LARC/MIP-3α was better induced by phorbol ester, whereas in HEp-2 epidermal carcinoma cells IL-1β was the superior inducer. The production levels of LARC/MIP-3α (1–10 ng/ml) were, on the average, 10- to 100-fold lower than those of IL-8 and MCP-1, but were comparable to those of other less abundantly secreted chemokines. Natural LARC/MIP-3α protein isolated from stimulated leukocytes or tumor cell lines showed molecular diversity, in that NH2- and COOH-terminally truncated forms were purified and identified by amino acid sequence analysis and mass spectrometry. In contrast to other chemokines, including MCP-1 and IL-8, the natural processing did not affect the calcium-mobilizing capacity of LARC/MIP-3α through its receptor CCR6. Furthermore, truncated natural LARC/MIP-3α isoforms were equally chemotactic for lymphocytes as intact rLARC/MIP-3α. It is concluded that in addition to its role in homeostatic trafficking of leukocytes, LARC/MIP-3α can function as an inflammatory chemokine during host defense.
Lipopolysaccharide-Binding Protein Is Vectorially Secreted and Transported by Cultured Intestinal Epithelial Cells and Is Present in the Intestinal Mucus of Mice
Authors: Vreugdenhil Anita C. E. , Snoek A. M. Patricia , Greve Jan Willem M. , Buurman Wim A. 
Published: April 2014

AbstractLipopolysaccharide-binding protein (LBP) is an important modulator of the host’s response to endotoxin. In a previous study, we found evidence for the synthesis of LBP by intestinal epithelial cells. In this study, we explored the polarity of LBP secretion by these cells. Polarized monolayers of Caco-2 cells were used as intestinal mucosa model. Cells were stimulated apically or basally with cytokines, and LBP secretion was analyzed. Furthermore, the presence of LBP in intestinal mucus of healthy and endotoxemic mice was studied using a mucus-sampling technique. The constitutive unipolar LBP secretion from the apical cell surface was markedly enhanced when cells were exposed to cytokines at their apical surface. However, bioactive LBP was secreted from both cell surfaces after basolateral stimulation of cells. Cytokines also influenced the secretion of the acute phase proteins serum amyloid A, apoA-I, and apoB from both surfaces of Caco-2 cells. Furthermore, transport of exogenous LBP from the basolateral to the apical cell surface was demonstrated. In line with these in vitro data, the presence of LBP in intestinal mucus was strongly enhanced in mice after a challenge with endotoxin. The results indicate that LBP is present at the mucosal surface of the intestine, a phenomenon for which secretion and transport of LBP by intestinal epithelial cells may be responsible.
Partially TAP-Independent Protection AgainstListeria monocytogenesby H2-M3-Restricted CD8+ T Cells
Authors: Rolph Michael S. , Kaufmann Stefan H. E. 
Published: April 2014

AbstractEffective protection against Listeria monocytogenes requires Ag-specific CD8+ T cells. A substantial proportion of CD8+ T cells activated during L. monocytogenes infection of C57BL/6 mice are restricted by the MHC class Ib molecule H2-M3. In this study, an H2-M3-restricted CD8+ T cell clone specific for a known H2-M3 epitope (fMIGWII) was generated from L. monocytogenes-infected mice. The clone was cytotoxic, produced IFN-γ, and could mediate strong protection against L. monocytogenes when transferred to infected mice. Macrophages pulsed with heat-killed Listeriae presented Ag to the clone in a TAP-independent manner. Both TAP-independent and -dependent processing occurred in vivo, as TAP-deficient mice infected with L. monocytogenes were partially protected by adoptive transfer of the clone. This is the first example of CD8+ T cell-mediated, TAP-independent protection against a pathogen in vivo, confirming the importance of alternative MHC class I processing pathways in the antibacterial immunity.
The Synthetic Peptide Trp-Lys-Tyr-Met-Val-d-Met Is a Potent Chemotactic Agonist for Mouse Formyl Peptide Receptor
Authors: He Rong , Tan Lijun , Browning Darren D. , Wang Ji Ming , Ye Richard D. 
Published: April 2014

AbstractFormyl peptides are potent neutrophil chemoattractants. In humans and rabbits, the formyl peptide receptor (FPR) binds N-formyl-Met-Leu-Phe (fMLF) with high affinity (Kd ≈ 1 nM). The mouse FPR (mFPR) is a low-affinity receptor for fMLF (Kd ≈ 100 nM); therefore, other agonists for this receptor may exist. Using mFPR-transfected rat basophilic leukemia cells, we found that a recently identified synthetic peptide Trp-Lys-Tyr-Met-Val-d-Met (WKYMVm) is a potent agonist for mFPR. WKYMVm induced calcium mobilization with an EC50 of 1.2–1.5 nM. Optimal chemotaxis was achieved with 1 nM of WKYMVm, but it required 100 nM of fMLF. WKYMVm stimulated rapid and potent phosphorylation of the mitogen-activated protein kinases extracellular signal-related kinases 1 and 2 when used at 50 nM. Pertussis toxin only partially blocked calcium mobilization and production of inositol 1,4,5-trisphosphate in the stimulated mFPR cells, suggesting the possibility that this receptor couples to Gα proteins other than Gi and Go. Competitive binding and desensitization data suggest that both peptides interact with the same receptor but may use nonoverlapping binding sites because WKYMVm was unable to effectively displace [3H]fMLF bound to mFPR. These results provide evidence for the presence of an alternative potent agonist for mFPR, and suggest a potential usage of WKYMVm for probing the ligand-receptor interactions with the murine formyl peptide receptor homologs.
Role of Intracellular Chloride in the Reversible Activation of Neutrophil β2 Integrins: A Lesson from TNF Stimulation
Authors: Menegazzi Renzo , Busetto Sara , Cramer Rita , Dri Pietro , Patriarca Pierluigi 
Published: April 2014

AbstractThe process of β2 integrin activation, which enhances the interaction of these heterodimers with ligands, plays a crucial role in the adherence-dependent neutrophilic polymorphonuclear leukocytes’ (PMN) responses to TNF. Our previous observation, showing that a marked decrease of the high basal Cl− content (Cl−i) is an essential step in the TNF-induced activation of PMN, stimulated this study, which investigates the role of alterations of Cl−i in the activation of β2 integrins triggered by TNF. Here we show that TNF enhances the expression of activation-specific neoepitopes of β2 integrins, namely, epitope 24, a unique epitope present on all three leukocyte integrin α subunits, and epitope CBRM1/5, localized to the I domain on the α-chain of Mac-1 (CD11bCD18). Moreover, we demonstrate that the conformational changes underlying the expression of the neoepitopes are dependent on a drop in Cl−i because 1) inhibition of Cl−i decrease is invariably accompanied by inhibition of β2 integrin activation, 2) Cl−i decrease induced by means other than agonist stimulation, i.e., by placing PMN in Cl−-free buffers, activates β2 integrins, and 3) restoration of the original Cl−i levels is accompanied by deactivation of β2 integrins. We also show that Cl−i decrease is required for TNF-induced cytoplasmic alkalinization, but such a rise in pHi does not seem to be relevant for β2 integrin activation. The results of our study emphasize the role of Cl− as a new PMN “second messenger.”
IL-18 Has IL-12-Independent Effects in Delayed-Type Hypersensitivity: Studies in Cell-Mediated Crescentic Glomerulonephritis
Authors: Kitching A. Richard , Tipping Peter G. , Kurimoto Masashi , Holdsworth Stephen R. 
Published: April 2014

AbstractIL-18 (formerly known as IFN-γ-inducing factor) enhances Th1 responses via effects that are thought to be dependent on and synergistic with IL-12. The potential for IL-18 to exert IL-12-independent effects in delayed-type hypersensitivity (DTH) responses was studied in a model of Th1-directed, DTH-mediated crescentic glomerulonephritis induced by planting an Ag in glomeruli of sensitized mice as well as in cutaneous DTH. Sensitized genetically normal (IL-12+/+) mice developed proteinuria and crescentic glomerulonephritis with a glomerular influx of DTH effectors (CD4+ T cells, macrophages, and fibrin deposition) in response to the planted glomerular Ag. IL-12p40-deficient (IL-12−/−) mice showed significant reductions in crescent formation, proteinuria, and glomerular DTH effectors. Administration of IL-18 to IL-12−/− mice restored the development of histological (including effectors of DTH) and functional glomerular injury in IL-12−/− mice to levels equivalent to those in IL-12+/+ mice. IL-18 administration to IL-12−/− mice increased glomerular ICAM-1 protein expression, but did not restore Ag-stimulated splenocyte IFN-γ, GM-CSF, IL-2, or TNF-α production. Sensitized IL-12+/+ mice also developed cutaneous DTH following intradermal challenge with the nephritogenic Ag. Cutaneous DTH was inhibited in IL-12−/− mice, but was restored by administration of IL-18. IL-12+/+ mice given IL-18 developed augmented injury, with enhanced glomerular and cutaneous DTH, demonstrating the synergistic effects of IL-18 and IL-12 in DTH responses. These studies demonstrate that even in the absence of IL-12, IL-18 can induce in vivo DTH responses and up-regulate ICAM-1 without inducing IFN-γ, GM-CSF, or TNF-α production.
Cutting Edge: TGF-β Inhibits Th Type 2 Development Through Inhibition of GATA-3 Expression
Authors: Gorelik Leonid , Fields Patrick E. , Flavell Richard A. 
Published: April 2014

Abstract
TGF-β is an important immunomodulatory cytokine that can inhibit differentiation of effector T cells. In this report, we address the molecular mechanisms through which TGF-β inhibits differentiation of CD4+ cells into Th type 2 cells. We demonstrate that TGF-β inhibits GATA-3 expression in developing Th cells. We also show that inhibition of GATA-3 expression by TGF-β is a major mechanism of inhibition of Th2 differentiation by TGF-β as ectopic expression of GATA-3 in developing T cells overcomes the ability of TGF-β to inhibit Th2 differentiation. TGF-β likely inhibits GATA-3 expression at the transcriptional level and does so without interfering with IL-4 signaling.
Cutting Edge: Anti-CD154 Therapeutic Antibodies Induce Infectious Transplantation Tolerance
Authors: Graca Luis , Honey Karen , Adams Elizabeth , Cobbold Stephen P. , Waldmann Herman 
Published: April 2014

Abstract
Nondepleting anti-CD154 (CD40 ligand) mAbs have proven effective in inducing transplantation tolerance in rodents and primates. In the induction phase, anti-CD154 Ab therapy is known to enhance apoptosis of Ag reactive T cells. However, this may not be the sole explanation for tolerance, as we show in this study that tolerance is maintained through a dominant regulatory mechanism which, like tolerance induced with CD4 Abs, manifests as infectious tolerance. Therefore, tolerance induced with anti-CD154 Abs involves not only the deletion of potentially aggressive T cells, but also a contagious spread of tolerance to new cohorts of graft-reactive T cells as they arise.
Cutting Edge: CD1d Deficiency Impairs Murine Host Defense Against the Spirochete, Borrelia burgdorferi
Authors: Kumar Hemant , Belperron Alexia , Barthold Stephen W. , Bockenstedt Linda K. 
Published: April 2014

Abstract
CD1 molecules can present microbial lipid Ag to T cells, suggesting that they participate in host defense against pathogens. In this study, we examined the role of CD1d in resistance to infection with the Lyme disease spirochete, Borrelia burgdorferi (Bb), an organism with proinflammatory lipid Ag. Bb infection of CD1d-deficient (CD1d−/−) mouse strains normally resistant to this pathogen resulted in arthritis. Pathology correlated with an increased prevalence of spirochete DNA in tissues and enhanced production of Bb-specific IgG, including IgG to Ag rapidly down-modulated on spirochetes in vivo. CD1d−/− mice exhibited high-titer Bb-specific IgG2a, an isotype commonly induced in disease-susceptible mice but not in the disease-resistant control mice in this study. These results show that CD1d deficiency impairs host resistance to a spirochete pathogen, and are the first example of a mutation that imparts Bb-resistant mice with the Ab and disease profile of a susceptible mouse strain.
Receptor Engagement on Cells Expressing a Ligand for the Tolerance-Inducing Molecule OX2 Induces an Immunoregulatory Population That Inhibits Alloreactivity In Vitro and In Vivo
Authors: Gorczynski Reginald M. , Yu Kai , Clark David 
Published: April 2014

Abstract
Increased survival of C57BL/6 renal allografts following portal vein donor-specific pretransplant immunization of C3H mice is associated with increased expression of the molecule OX2 seen on host dendritic cells, along with a marked polarization in cytokine production from lymphocytes harvested from the transplanted animals, with preferential production of IL-4, IL-10, and TGF-β on donor-specific restimulation in vitro, and decreased production of IL-2, IFN-γ, and TNF-α compared with non-portal vein-immunized control transplanted mice. The increased renal allograft survival and the altered cytokine production are abolished by infusion of anti-mouse OX2 mAb (3B6). Infusion of a soluble OX2:Fc immunoadhesin can itself produce significant prolongation of xeno- and allografts in mice. We have used FITC-conjugated OX2:Fc to characterize cells expressing a ligand (OX2L) for OX2, and provide evidence that subpopulations of LPS-stimulated splenic macrophages, Con A-activated splenic T cells, and the majority (&gt;80%) of γδTCR+ T cells express this ligand. We show below that F4/80+, OX2L+ splenic macrophages, admixed with OX2:Fc, represent a potent immunosuppressive population capable of causing more profound inhibition of alloreactivity in vitro or in vivo than that seen using either OX2:Fc or OX2+ (or OX2L+) cells alone. Immunoregulation by this OX2L+ population occurs in an MHC-restricted fashion.
IFN-α Suppresses Activation of Nuclear Transcription Factors NF-κB and Activator Protein 1 and Potentiates TNF-Induced Apoptosis
Authors: Manna Sunil K. , Mukhopadhyay Asok , Aggarwal Bharat B. 
Published: April 2014

Abstract
We and others have reported that IFN-α potentiates the apoptotic effects of TNF through a mechanism that is not understood. Because the nuclear transcription factors NF-κB and AP-1 have recently been reported to mediate anti-apoptosis and cell survival, we hypothesized that IFN-α potentiates the cytotoxic effects of TNF by suppressing TNF-induced activation of NF-κB and AP-1. We tested this hypothesis by pretreating human Jurkat T cells with IFN-α, which blocked TNF-induced activation of NF-κB and AP-1 in a time- and dose-dependent manner as determined by EMSA. IFN-α blocked TNF-induced phosphorylation and degradation of the inhibitor subunit of NF-κB, and suppressed NF-κB and AP-1 activation induced by various other inflammatory stimuli. NF-κB-dependent reporter gene expression activated by TNF, TNFR1, TNF receptor-associated factor 2, and NF-κB-inducing kinase was also abrogated by IFN-α pretreatment. The suppression of NF-κB and AP-1 correlated with the potentiation of TNF-induced cytotoxicity and caspase activation. Overall our results suggest that IFN-α potentiates the apoptotic effects of TNF possibly by suppressing NF-κB and AP-1 activation.
Emergence of CD8+ T Cells Expressing NK Cell Receptors in Influenza A Virus-Infected Mice
Authors: Kambayashi Taku , Assarsson Erika , Michaëlsson Jakob , Berglund Peter , Diehl Alexander D. , Chambers Benedict J. , Ljunggren Hans-Gustaf 
Published: April 2014

Abstract
Both innate and adaptive immune responses play an important role in the recovery of the host from viral infections. In the present report, a subset of cells coexpressing CD8 and NKR-P1C (NK1.1) was found in the lungs of mice infected with influenza A virus. These cells were detected at low numbers in the lungs of uninfected mice, but represented up to 10% of the total CD8+ T cell population at day 10 postinfection. Almost all of the CD8+NK1.1+ cells were CD8αβ+CD3+TCRαβ+ and a proportion of these cells also expressed the NK cell-associated Ly49 receptors. Interestingly, up to 30% of these cells were virus-specific T cells as determined by MHC class I tetramer staining and by intracellular staining of IFN-γ after viral peptide stimulation. Moreover, these cells were distinct from conventional NKT cells as they were also found at increased numbers in influenza-infected CD1−/− mice. These results demonstrate that a significant proportion of CD8+ T cells acquire NK1.1 and other NK cell-associated molecules, and suggests that these receptors may possibly regulate CD8+ T cell effector functions during viral infection.