bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Structure and Stability of an HLA-A*0201/Octameric Tax Peptide Complex with an Empty Conserved Peptide-N-Terminal Binding Site
Authors: Khan Amir R. , Baker Brian M. , Ghosh Partho , Biddison William E. , Wiley Don C. 
Published: April 2014

AbstractThe crystal structure of the human class I MHC molecule HLA-A2 complexed with of an octameric peptide, Tax8 (LFGYPVYV), from human T cell lymphotrophic virus-1 (HTLV-1) has been determined. This structure is compared with a newly refined, higher resolution (1.8 Å) structure of HLA-A2 complexed with the nonameric Tax9 peptide (LLFGYPVYV) with one more N-terminal residue. Despite the absence of a peptide residue (P1) bound in the conserved N-terminal peptide-binding pocket of the Tax8/HLA-A2 complex, the structures of the two complexes are essentially identical. Water molecules in the Tax8 complex replace the terminal amino group of the Tax9 peptide and mediate a network of hydrogen bonds among the secondary structural elements at that end of the peptide-binding groove. Thermal denaturation measurements indicate that the Tax8 complex is much less stable, ΔTm = 16°C, than the Tax9 complex, but both can sensitize target cells for lysis by some Tax-specific CTL from HTLV-1 infected individuals. The absence of a P1 peptide residue is thus not enough to prevent formation of a “closed conformation” of the peptide-binding site. TCR affinity measurements and cytotoxic T cell assays indicate that the Tax8/HLA-A2 complex does not functionally cross-react with the A6-TCR-bearing T cell clone specific for Tax9/HLA-A2 complexes.
IL-10 and the Dangers of Immune Polarization: Excessive Type 1 and Type 2 Cytokine Responses Induce Distinct Forms of Lethal Immunopathology in Murine Schistosomiasis
Authors: Hoffmann Karl F. , Cheever Allen W. , Wynn Thomas A. 
Published: April 2014

AbstractTo dissect the controversial roles of type 1 and type 2 cytokines to the pathogenesis of schistosomiasis, we generated IL-10/IL-4- and IL-10/IL-12-deficient mice that develop highly polarized type 1 and type 2 cytokine responses, respectively. Interestingly, the Th1-polarized IL-10/IL-4-deficient mice rapidly lost weight at the onset of egg-laying and displayed 100% mortality by wk 9 postinfection. This acute mortality was linked to overexpression of the proinflammatory mediators IFN-γ, TNF-α, and inducible NO and the formation of nonfibrotic granulomas. Elevated serum aspartate transaminase levels confirmed that mortality was in part attributable to acute hepatotoxicity. In contrast, the Th2-polarized IL-10/IL-12-deficient mice developed a progressive wasting disease that correlated with increased hepatic fibrosis, formation of large eosinophil-rich granulomas, a 10-fold increase in IL-4 and IL-13, and significant mortality during the chronic stages of infection. Surprisingly, IL-10-deficient mice displayed pathological features that were characteristic of both extremes, while wild-type mice developed relatively successful long term chronic infections. These data demonstrate that IL-10 significantly suppresses type 1 and type 2 cytokine development in IL-4- and IL-12-deficient mice, respectively, thereby impeding the development of severe egg-induced pathology in the single cytokine-deficient animals. Together, these findings reveal the central regulatory role of IL-10 in the pathogenesis of schistosomiasis and illustrate that excessive type 1 and type 2 cytokine responses trigger distinct, but equally detrimental, forms of pathology following infection.
Infection of B Cell-Deficient Mice with CDC 1551, a Clinical Isolate ofMycobacterium tuberculosis: Delay in Dissemination and Development of Lung Pathology
Authors: Bosio Catharine M. , Gardner Donald , Elkins Karen L. 
Published: April 2014

AbstractLong-term survival of mice infected with Mycobacterium tuberculosis is dependent upon IFN-γ and T cells, but events in early phases of the immune response are not well understood. In this study, we describe a role for B cells during early immune responses to infection with a clinical isolate of M. tuberculosis (CDC 1551). Following a low-dose infection with M. tuberculosis CDC 1551, similar numbers of bacteria were detected in the lungs of both B cell knockout (IgH 6−, BKO) and C57BL/6J (wild-type) mice. However, despite comparable bacterial loads in the lungs, less severe pulmonary granuloma formation and delayed dissemination of bacteria from lungs to peripheral organs were observed in BKO mice. BKO mice reconstituted with naive B cells, but not those given M. tuberculosis-specific Abs, before infection developed pulmonary granulomas and dissemination patterns similar to wild-type animals. Further analysis of lung cell populations revealed greater numbers of lymphocytes, especially CD8+ T cells, macrophages, and neutrophils in wild-type and reconstituted mice than in BKO mice. Thus, less severe lesion formation and delayed dissemination of bacteria found in BKO mice were dependent on B cells, not Abs, and were associated with altered cellular infiltrate to the lungs. These observations demonstrate an important, previously unappreciated, role for B cells during early immune responses to M. tuberculosis infections.
A Filarial Nematode-Secreted Product Signals Dendritic Cells to Acquire a Phenotype That Drives Development of Th2 Cells
Authors: Whelan Michael , Harnett Margaret M. , Houston Katrina M. , Patel Vanshree , Harnett William , Rigley Kevin P. 
Published: April 2014

Abstract
Although exogeneous “danger” signals such as LPS can activate APC to produce a Th1 response, the nature of events initiating a Th2 response is controversial. We now show that pathogen-derived products have the capacity to induce bone marrow-derived dendritic cell cultures to acquire a phenotype that promotes the differentiation of naive CD4+ T cells toward either a Th1 or Th2 phenotype. Thus, LPS-matured dendritic cells (DC1) promote a Th1 response (increased generation of IFN-γ and reduced production of IL-4) by Ag-stimulated CD4+ T cells from the DO.11.10 transgenic mouse expressing a TCR specific for an OVA peptide (OVA323–339). In contrast, a phosphorylcholine-containing glycoprotein, ES-62, secreted by the filarial nematode, Acanthocheilonema viteae, which generates a Th2 Ab response in vivo, is found to induce the maturation of dendritic cells (DC2) with the capacity to induce Th2 responses (increased IL-4 and decreased IFN-γ). In addition, we show that the switch to either Th1 or Th2 responses is not effected by differential regulation through CD80 or CD86 and that a Th2 response is achieved in the presence of IL-12.
Neutrophil-Induced Changes in the Biomechanical Properties of Endothelial Cells: Roles of ICAM-1 and Reactive Oxygen Species
Authors: Wang Qin , Doerschuk Claire M. 
Published: April 2014

AbstractThis study evaluated the changes in the biomechanical properties of endothelial cells (ECs) induced by neutrophil adhesion and the roles of ICAM-1 and reactive oxygen species (ROS) in modulating these changes. Neutrophil adherence to 24-h TNF-α-activated pulmonary microvascular ECs induced an increase in the apparent stiffness of ECs within 2 min, measured with magnetic twisting cytometry. An anti-ICAM-1 Ab blocked the EC stiffening response without inhibiting neutrophil adherence. Moreover, cross-linking ICAM-1 mimicked the stiffening response induced by neutrophils. The neutrophil-induced increase in the apparent stiffness of ECs was inhibited with 1% DMSO (a hydroxyl radical scavenger), allopurinol (a xanthine oxidase inhibitor), or deferoxamine (an iron chelator), suggesting that ROS may be involved in mediating the EC stiffening response. The cellular sources of ROS were determined by measuring the oxidation of dichlorofluorescein. Neutrophil adherence to TNF-α-activated ECs induced ROS production only in ECs, and not in neutrophils. This ROS production in ECs was completely prevented by the anti-ICAM-1 Ab and partially inhibited by allopurinol. These results suggest that ICAM-1-mediated signaling events during neutrophil adherence may activate xanthine oxidase, which in turn mediates the ROS production in ECs that leads to stiffening. ROS generated in ECs on neutrophil adherence appear to mediate cytoskeletal remodeling, which may modulate subsequent inflammatory responses.
Peroxisome Proliferator-Activated Receptor-γ Activators Inhibit IFN-γ-Induced Expression of the T Cell-Active CXC Chemokines IP-10, Mig, and I-TAC in Human Endothelial Cells
Authors: Marx Nikolaus , Mach François , Sauty Alain , Leung Josephine H. , Sarafi Mindy N. , Ransohoff Richard M. , Libby Peter , Plutzky Jorge , Luster Andrew D. 
Published: April 2014

AbstractPeroxisome proliferator-activated receptor-γ (PPARγ), a member of the nuclear hormone receptor superfamily originally shown to play an important role in adipocyte differentiation and glucose homeostasis, is now known to regulate inflammatory responses. Given the importance of endothelial cell (EC)-derived chemokines in regulating leukocyte function and trafficking, we studied the effects of PPARγ ligands on the expression of chemokines induced in ECs by the Th1 cytokine IFN-γ. Treatment of ECs with PPARγ activators significantly inhibited IFN-γ-induced mRNA and protein expression of the CXC chemokines IFN-inducible protein of 10 kDa (IP-10), monokine induced by IFN-γ (Mig), and IFN-inducible T-cell α-chemoattractant (I-TAC), whereas expression of the CC chemokine monocyte chemoattractant protein-1 was not altered. PPARγ activators decreased IFN-inducible protein of 10 kDa promoter activity and inhibited protein binding to the two NF-κB sites but not to the IFN-stimulated response element ISRE site. Furthermore, PPARγ ligands inhibited the release of chemotactic activity for CXC chemokine receptor 3 (CXCR3)-transfected lymphocytes from IFN-γ-stimulated ECs. These data suggest that anti-diabetic PPARγ activators might attenuate the recruitment of activated T cells at sites of Th1-mediated inflammation.
Phagocytosis of Nonapoptotic Cells Dying by Caspase- Independent Mechanisms
Authors: Hirt Ulrich A. , Gantner Florian , Leist Marcel 
Published: April 2014

AbstractCaspase activation, exposure of phosphatidylserine (PS) on the outer surface of the plasma membrane, and rapid phagocytic removal of dying cells are key features of apoptosis. Nonapoptotic/necrotic modes of death occur independent of caspase activation, but the role of phagocytosis is largely unknown. To address this issue, we studied phagocytosis by human monocyte-derived macrophages (HMDM) and rat microglial cells. Target cells (Jurkat) were stimulated by several different methods that all caused caspase-independent death. First, we induced necrosis by combining toxins with ATP-depleting agents. Under these conditions, neither PS was exposed nor were such cells phagocytosed before their death. However, once the plasma membrane integrity was lost, the dead cells were rapidly and efficiently engulfed by HMDM. Next, we triggered Jurkat cell death with staurosporine in the presence of the pan-caspase inhibitor zVAD-fmk. Under these conditions, death occurred by delayed necrosis and without exposure of PS. Nevertheless, such lethally challenged cells were phagocytosed before the loss of membrane integrity. Finally, we triggered Ca2+ influx in Jurkat cells with an ionophore, or in neurons by glutamate receptor stimulation, respectively. In both models, PS was exposed on the cell surface. Ca2+-stressed cells were phagocytosed starting at 30 min after stimulation. Protein kinase C inhibitors prevented Ca2+-mediated PS exposure and phagocytosis. Essentially, similar phagocytosis data were obtained for all models with HMDM and microglia. We conclude that also cells dying nonapoptotically and independent of caspase activation may be recognized and removed before, or very quickly after, membrane lysis.
Differential Mitogen-Activated Protein Kinase Stimulation by Fcγ Receptor IIa and Fcγ Receptor IIIb Determines the Activation Phenotype of Human Neutrophils
Authors: Coxon Patricia Y. , Rane Madhavi J. , Powell David W. , Klein Jon B. , McLeish Kenneth R. 
Published: April 2014

AbstractFcγRs mediate immune complex-induced tissue injury. The hypothesis that FcγRIIa and FcγRIIIb control neutrophil responses by activating mitogen-activated protein kinases was examined. Homotypic and heterotypic cross-linking of FcγRIIa and/or FcγRIIIb resulted in a rapid, transient increase in ERK and p38 activity, with maximal stimulation between 1 and 3 min. FcγRIIa and FcγRIIIb stimulated distinct patterns of ERK and p38 activity, and heterotypic cross-linking failed to stimulate synergistic activation of either ERK or p38 activity. Both FcγRIIa and FcγRIIIb required activation of a nonreceptor tyrosine kinase and phosphatidylinositol 3-kinase for stimulation of ERK and p38. Inhibition of ERK activation with PD98059 enhanced H2O2 production stimulated by homotypic and heterotypic FcγR cross-linking. Inhibition of p38 with SB203580 attenuated H2O2 production stimulated by FcγRIIIb or heterotypic cross-linking, but had no effect on FcγRIIa-stimulated H2O2 production. On the other hand, PD98059 inhibited actin polymerization stimulated by FcγR cross-linking, while SB203580 had no effect. Inhibition of actin polymerization with cytochalasin D enhanced p38 activity stimulated by either FcγRIIa or FcγRIIIb, but cytochalasin D only enhanced H2O2 production stimulated by FcγRIIIb. Our data indicate that FcγRIIa and FcγRIIIb independently activate ERK and p38. The two receptors demonstrate different efficacies for ERK and p38 activation, and they do not act cooperatively. ERK and p38 provide stimulatory and inhibitory signals for neutrophil responses to immune complexes. In addition, these data indicate that actin reorganization may play a role in mediating p38-dependent activation of respiratory burst upon stimulation of FcγRIIIb in neutrophils.
Release of Calcium from Inositol 1,4,5-Trisphosphate Receptor-Regulated Stores by HIV-1 Tat Regulates TNF-α Production in Human Macrophages
Authors: Mayne Michael , Holden Clark P. , Nath Avindra , Geiger Jonathan D. 
Published: April 2014

Abstract
HIV-1 protein Tat is neurotoxic and increases macrophage and microglia production of TNF-α, a cytopathic cytokine linked to the neuropathogenesis of HIV dementia. Others have shown that intracellular calcium regulates TNF-α production in macrophages, and we have shown that Tat releases calcium from inositol 1,4,5-trisphosphate (IP3) receptor-regulated stores in neurons and astrocytes. Accordingly, we tested the hypothesis that Tat-induced TNF-α production was dependent on the release of intracellular calcium from IP3-regulated calcium stores in primary macrophages. We found that Tat transiently and dose-dependently increased levels of intracellular calcium and that this increase was blocked by xestospongin C, pertussis toxin, and by phospholipase C and type 1 protein kinase C inhibitors but not by protein kinase A or phospholipase A2 inhibitors. Xestospongin C, BAPTA-AM, U73122, and bisindolylmalemide significantly inhibited Tat-induced TNF-α production. These results demonstrate that in macrophages, Tat-induced release of calcium from IP3-sensitive intracellular stores and activation of nonconventional PKC isoforms play an important role in Tat-induced TNF-α production.
Lymphocyte Migration Through Monolayers of Endothelial Cell Lines Involves VCAM-1 Signaling Via Endothelial Cell NADPH Oxidase
Authors: Matheny Heather E. , Deem Tracy L. , Cook-Mills Joan M. 
Published: April 2014

Abstract
Lymphocytes migrate from the blood across endothelial cells to reach foreign substances sequestered in peripheral lymphoid organs and inflammatory sites. To study intracellular signaling in endothelial cells during lymphocyte migration, we used murine endothelial cell lines that promote lymphocyte migration and constitutively express VCAM-1. The maximum rate of resting splenic lymphocyte migration across monolayers of the endothelial cells occurred at 0–24 h. This migration was inhibited by anti-VCAM-1 or anti-α4 integrin, suggesting that VCAM-1 adhesion was required for migration. To determine whether signals within the endothelial cells were required for migration, irreversible inhibitors of signal transduction molecules were used to pretreat the endothelial cell lines. Inhibitors of NADPH oxidase activity (diphenyleneiodonium and apocynin) blocked migration &gt;65% without affecting adhesion. Because NADPH oxidase catalyzes the production of reactive oxygen species (ROS), we examined whether ROS were required for migration. Scavengers of ROS inhibited migration without affecting adhesion. Furthermore, VCAM-1 ligand binding stimulated NADPH oxidase-dependent production of ROS by the endothelial cells lines and primary endothelial cell cultures. Finally, VCAM-1 ligand binding induced an apocynin-inhibitable actin restructuring in the endothelial cell lines at the location of the lymphocyte or anti-VCAM-1-coated bead, suggesting that an NADPH oxidase-dependent endothelial cell shape change was required for lymphocyte migration. In summary, VCAM-1 signaled the activation of endothelial cell NADPH oxidase, which was required for lymphocyte migration. This suggests that endothelial cells are not only a scaffold for lymphocyte adhesion, but play an active role in promoting lymphocyte migration.
Characterization of Human γ-Tryptases, Novel Members of the Chromosome 16p Mast Cell Tryptase and Prostasin Gene Families
Authors: Caughey George H. , Raymond Wilfred W. , Blount John L. , Hau Leola W.-T. , Pallaoro Michele , Wolters Paul J. , Verghese George M. 
Published: April 2014

Abstract
Previously, this laboratory identified clusters of α-, β-, and mast cell protease-7-like tryptase genes on human chromosome 16p13.3. The present work characterizes adjacent genes encoding novel serine proteases, termed γ-tryptases, and generates a refined map of the multitryptase locus. Each γ gene lies between an α1H Ca2+ channel gene (CACNA1H) and a βII- or βIII-tryptase gene and is ∼30 kb from polymorphic minisatellite MS205. The tryptase locus also contains at least four tryptase-like pseudogenes, including mastin, a gene expressed in dogs but not in humans. Genomic DNA blotting results suggest that γI- and γII-tryptases are alleles at the same site. βII- and βIII-tryptases appear to be alleles at a neighboring site, and αII- and βI-tryptases appear to be alleles at a third site. γ-Tryptases are transcribed in lung, intestine, and in several other tissues and in a mast cell line (HMC-1) that also expresses γ-tryptase protein. Immunohistochemical analysis suggests that γ-tryptase is expressed by airway mast cells. γ-Tryptase catalytic domains are ∼48% identical with those of known mast cell tryptases and possess mouse homologues. We predict that γ-tryptases are glycosylated oligomers with tryptic substrate specificity and a distinct mode of activation. A feature not found in described tryptases is a C-terminal hydrophobic domain, which may be a membrane anchor. Although the catalytic domains contain tryptase-like features, the hydrophobic segment and intron-exon organization are more closely related to another recently described protease, prostasin. In summary, this work describes γ-tryptases, which are novel members of chromosome 16p tryptase/prostasin gene families. Their unique features suggest possibly novel functions.
Prolonged Elevation of IL-1 inPseudomonas aeruginosaOcular Infection Regulates Macrophage-Inflammatory Protein-2 Production, Polymorphonuclear Neutrophil Persistence, and Corneal Perforation
Authors: Rudner Xiaowen L. , Kernacki Karen A. , Barrett Ronald P. , Hazlett Linda D. 
Published: April 2014

AbstractThe kinetics of IL-1 (α and β) production after Pseudomonas aeruginosa corneal infection was examined in susceptible (cornea perforates) C57BL/6J (B6) and resistant (cornea heals) BALB/cByJ (BALB/c) mice. IL-1α and -1β (mRNA and protein) were elevated in both mouse strains, and levels peaked at 1 day postinfection (p.i.). Significantly greater amounts of IL-1 protein were detected in B6 vs BALB/c mice at 1 and 3 days p.i. At 5 days p.i., IL-1α and -1β (mRNA and protein) remained elevated in B6, but began to decline in BALB/c mice. To test the significance of elevated IL-1 in B6 mice, a polyclonal neutralizing Ab against IL-1β was used to treat infected B6 mice. A combination of subconjunctival and i.p. administration of IL-1β polyclonal Ab significantly reduced corneal disease. The reduction in disease severity in infected B6 mice was accompanied by a reduction in corneal polymorphonuclear neutrophil number, bacterial load, and macrophage inflammatory protein-2 mRNA and protein levels. These data provide evidence that IL-1 is an important contributor to P. aeruginosa corneal infection. At least one mechanism by which prolonged and/or elevated IL-1 expression contributes to irreversible corneal tissue destruction appears to be by increasing macrophage inflammatory protein-2 production, resulting in a prolonged stimulation of polymorphonuclear neutrophil influx into cornea. In contrast, a timely down-regulation of IL-1 appears consistent with an inflammatory response that is sufficient to clear the bacterial infection with less corneal damage.
Recurrent Respiratory Syncytial Virus Infections in Allergen-Sensitized Mice Lead to Persistent Airway Inflammation and Hyperresponsiveness
Authors: Matsuse Hiroto , Behera Aruna K. , Kumar Mukesh , Rabb Hamid , Lockey Richard F. , Mohapatra Shyam S. 
Published: April 2014

AbstractRespiratory syncytial virus (RSV) infection is considered a risk factor for bronchial asthma; however, the synergy between allergen sensitization and RSV infection in the development of pulmonary inflammation and asthma has been controversial. In this study the effects of primary and recurrent RSV infection on allergic asthma were examined in a group of control, RSV-infected, Dermatophagoides farinae (Df) allergen-sensitized, and Df allergen-sensitized plus RSV-infected BALB/c mice. Primary RSV infection in Df-sensitized mice transiently increases airway responsiveness, which is accompanied by increases in eosinophilic infiltration, the expression of ICAM-1, and macrophage inflammatory protein-1α (MIP-1α) in the lung tissue. A secondary RSV infection persistently enhances airway responsiveness in Df-sensitized mice, with a concomitant increase in MIP-1α and RSV Ag load in lung tissues. Bulk cultures of thoracic lymph node mononuclear cells demonstrate that acute RSV infection augments both Th1- and Th2-like cytokines, whereas secondary and tertiary infections shift the cytokine profile in favor of the Th2-like cytokine response in Df-sensitized mice. The elevated total serum IgE level in the Df-sensitized mice persists following only RSV reinfection. Thus, recurrent RSV infections in Df-sensitized mice augment the synthesis of Th2-like cytokines, total serum IgE Abs, and MIP-1α, which are responsible for persistent airway inflammation and hyperresponsiveness, both of which are characteristics of asthma.