bluuebunny/crossref_metadata_2025_split huggingface dataset:
Involvement of Protein Kinase Cε in the Negative Regulation of Akt Activation Stimulated by Granulocyte Colony-Stimulating Factor
Authors: Liu Hong , Qiu Yaling , Xiao Lei , Dong Fan 
Published: April 2014

Abstract
Stimulation of cells with G-CSF activates multiple signaling cascades, including the serine/threonine kinase Akt pathway. We show in this study that G-CSF-induced activation of Akt in myeloid 32D was specifically inhibited by treatment with PMA, a protein kinase C (PKC) activator. PMA treatment also rapidly attenuated sustained Akt activation mediated by a carboxy truncated G-CSF receptor, expressed in patients with acute myeloid leukemia evolving from severe congenital neutropenia. The inhibitory effect of PMA was abolished by pretreatment of cells with specific PKC inhibitor GF109203X, suggesting that the PKC pathway negatively regulates Akt activation. Ro31-8820, a PKCε inhibitor, also abrogated PMA-mediated inhibition of Akt activation, whereas rottlerin and Go6976, inhibitors of PKCδ and PKCαβI, respectively, exhibited no significant effects. Furthermore, overexpression of the wild-type and a constitutively active, but not a kinase-dead, forms of PKCε markedly attenuated Akt activation, and inhibited the proliferation and survival of cells in response to G-CSF. The expression of PKCε was down-regulated with G-CSF-induced terminal granulocytic differentiation. Together, these results implicate PKCε as a negative regulator of Akt activation stimulated by G-CSF and indicate that PKCε plays a negative role in cell proliferation and survival in response to G-CSF.
Scaffolding Adapter Grb2-Associated Binder 2 Requires Syk to Transmit Signals from FcεRI
Authors: Yu Min , Lowell Cliff A. , Neel Benjamin G. , Gu Haihua 
Published: April 2014

Abstract
Scaffolding adapter Grb2-associated binder 2 (Gab2) is a key component of FcεRI signaling in mast cells, required for the activation of PI3K. To understand how Gab2 is activated in FcεRI signaling, we asked which protein tyrosine kinase is required for Gab2 phosphorylation. We found that Gab2 tyrosyl phosphorylation requires Lyn and Syk. In agreement with published results, we found that Fyn also contributes to Gab2 tyrosyl phosphorylation. However, Syk activation is defective in Fyn−/− mast cells, suggesting that Syk is the proximal kinase responsible for Gab2 tyrosyl phosphorylation. Then, we asked which domains in Gab2 are required for Gab2 tyrosyl phosphorylation. We found that the Grb2-Src homology 3 (SH3) binding sites are required for, whereas the pleckstrin homology (PH) domain contributes to, Gab2 tyrosyl phosphorylation. Using a protein/lipid overlay assay, we determined that the Gab2 PH domain preferentially binds the PI3K lipid products, PI3, 4,5P3 and PI3, 4P2. Furthermore, the Grb2-SH3 binding sites and PH domain binding to PI3K lipid products are required for Gab2 function in FcεRI-evoked degranulation and Akt activation. Our data strongly suggest a model for Gab2 action in FcεRI signaling. The Grb2 SH3 binding sites play a critical role in bringing Gab2 to FcεRI, whereupon Gab2 becomes tyrosyl-phosphorylated in a Syk-dependent fashion. Phosphorylated Gab2 results in recruitment and activation of PI3K, whose lipid products bind the PH domain of Gab2 and acts in positive feedback loop for sustained PI3K recruitment and phosphatidylinositol-3,4,5-trisphosphate production, required for FcεRI-evoked degranulation of mast cells.
The Molecular Basis for Galα(1,3)Gal Expression in Animals with a Deletion of the α1,3Galactosyltransferase Gene
Authors: Milland Julie , Christiansen Dale , Lazarus Brooke D. , Taylor Simon G. , Xing Pei Xiang , Sandrin Mauro S. 
Published: April 2014

Abstract
The production of homozygous pigs with a disruption in the GGTA1 gene, which encodes α1,3galactosyltransferase (α1,3GT), represented a critical step toward the clinical reality of xenotransplantation. Unexpectedly, the predicted complete elimination of the immunogenic Galα(1,3)Gal carbohydrate epitope was not observed as Galα(1,3)Gal staining was still present in tissues from GGTA1−/− animals. This shows that, contrary to previous dogma, α1,3GT is not the only enzyme able to synthesize Galα(1,3)Gal. As iGb3 synthase (iGb3S) is a candidate glycosyltransferase, we cloned iGb3S cDNA from GGTA1−/− mouse thymus and confirmed mRNA expression in both mouse and pig tissues. The mouse iGb3S gene exhibits alternative splicing of exons that results in a markedly different cytoplasmic tail compared with the rat gene. Transfection of iGb3S cDNA resulted in high levels of cell surface Galα(1,3)Gal synthesized via the isoglobo series pathway, thus demonstrating that mouse iGb3S is an additional enzyme capable of synthesizing the xenoreactive Galα(1,3)Gal epitope. Galα(1,3)Gal synthesized by iGb3S, in contrast to α1,3GT, was resistant to down-regulation by competition with α1,2fucosyltransferase. Moreover, Galα(1,3)Gal synthesized by iGb3S was immunogenic and elicited Abs in GGTA1 −/− mice. Galα(1,3)Gal synthesized by iGb3S may affect survival of pig transplants in humans, and deletion of this gene, or modification of its product, warrants consideration.
Cytolytic CD8+ T Cells Directed against a Cryptic Epitope Derived from a Retroviral Alternative Reading Frame Confer Disease Protection
Authors: Ho On , Green William R. 
Published: April 2014

AbstractCytolytic CD8+ T cells (CTL) are key to the immune response that controls virus infections and mediates disease protection. The ability of CTL to induce apoptosis of infected cells and/or limit viral replication is determined by recognition of processed viral peptide epitopes on the surface of the target cell. An understudied source of MHC class I-presented peptides is the aptly named “cryptic epitopes,” defined by their nontraditional methods of generation, including derivation from alternative reading frames (ARFs). Although ARF-encoded epitopes have now been documented in a few systems, their potential functional relevance in vivo has been debated. In this study, we demonstrate the physiological significance of an ARF-derived CTL epitope in a retrovirus-induced disease model. We show that disease-susceptible CD8-deficient mice reconstituted with CTL specific for the retroviral ARF-derived SYNTGRFPPL epitope controlled an infection by the LP-BM5 retrovirus isolate, evidently at the level of viral clearance, resulting in protection of these mice from disease. These data indicate that ARF-derived epitopes are indeed relevant inducers of the immune system and demonstrate the importance of atypically generated peptides as functional Ag with a physiologic role in disease protection.
Neutrophils Regulate Airway Responses in a Model of Fungal Allergic Airways Disease
Authors: Park Stacy J. , Wiekowski Maria T. , Lira Sergio A. , Mehrad Borna 
Published: April 2014

Abstract
Neutrophils infiltrate airway walls in patients with allergic airway diseases and in animal models of these illnesses, but their contribution to the pathogenesis of airway allergy is not established. We hypothesized that, in a mouse model of airway allergy to the ubiquitous environmental mold, Aspergillus fumigatus, airway neutrophils contribute to disease severity. Ab-mediated neutrophil depletion resulted in reduced airway hyperresponsiveness and remodeling, whereas conditional transgenic overexpression of the neutrophil chemotactic molecule, CXCL1, in airway walls resulted in worsened allergic responses. This worsened phenotype was associated with a marked increase in the number of airway neutrophils but not other lung leukocytes, including eosinophils and lymphocyte subsets, and depletion of neutrophils in sensitized mice with transgenic overexpression of CXCL1 resulted in attenuated airway responses. The number of lung neutrophils correlated with lung matrix metalloproteinase 9 (MMP-9) activity both in the context of neutrophil depletion and with augmented neutrophil recruitment to the airways. Although wild-type and MMP-9-deficient neutrophils homed to the inflamed airways to a similar extent, transfer of wild-type, but not MMP-9-deficient, neutrophils to MMP-9-deficient animals resulted in augmented allergic airway responses. Taken together, these data implicate neutrophils in the pathogenesis of fungal allergic airway disease.
Involvement of Group VIA Calcium-Independent Phospholipase A2 in Macrophage Engulfment of Hydrogen Peroxide-Treated U937 Cells
Authors: Pérez Rebeca , Balboa María A. , Balsinde Jesús 
Published: April 2014

Abstract
Hydrogen peroxide-induced apoptosis of U937 cells results in substantial hydrolysis of membrane phospholipids by calcium-independent group VIA phospholipase A2 (iPLA2-VIA). However, abrogation of cellular iPLA2-VIA neither delays nor decreases apoptosis, suggesting that, beyond a mere destructive role, iPLA2-VIA may serve other specific roles. In this study, we report that phagocytosis of apoptosing U937 cells by macrophages is blunted if the cells are depleted of iPLA2-VIA by treatment with an inhibitor or an antisense oligonucleotide, and it is augmented by overexpression of iPLA2-VIA in the dying cells. Thus, the magnitude of macrophage phagocytosis correlates with the level of iPLA2-VIA activity of the dying cells. Eliminating by antisense oligonucleotide technology of cytosolic group IVA phospholipase A2 does not attenuate phagocytosis of U937 dying cells by macrophages. Incubation of U937 cells with different fatty acids has no effect on either the extent of hydrogen peroxide-induced apoptosis or the degree of phagocytosis of the dying cells by macrophages. However, preincubation of the macrophages with lysophosphatidylcholine before exposing them to the dying cells blocks phagocytosis of the latter. These results indicate that formation of lysophosphatidylcholine by iPLA2-VIA in hydrogen peroxide-treated U937 cells to induce apoptosis directly contributes to their efficient clearance by macrophages.
Deletion of CCR1 Attenuates Pathophysiologic Responses during Respiratory Syncytial Virus Infection
Authors: Miller Allison L. , Gerard Craig , Schaller Matthew , Gruber Achim D. , Humbles Allison A. , Lukacs Nicholas W. 
Published: April 2014

Abstract
The role of chemokines in chronic inflammatory responses are central to the recruitment of particular subsets of leukocytes. In the present studies, we have examined the role of CCR1 in the developing pathogenesis of respiratory syncytial virus (RSV) in the lungs of infected BALB/c mice. Although we did not observe significant differences in clearance of RSV, we were able to identify decreased pathophysiologic responses in CCR1−/− mice. CCR1−/− mice displayed a significant reduction in both airway hyperresponsiveness and mucus production that corresponded to significant increases in IFN-γ and CXCL10. The goblet cell hyper/metaplasia and the expression of mucus-associated gene, gob5, were correspondingly reduced in the CCR1−/− mice. In addition, the Western blot analysis of gob5 protein indicated that CCR1−/− mice have virtually no up-regulation of the protein at day 6 of infection compared with wild-type-infected mice. Results from bone marrow chimeric mice indicated that partial reconstitution of the response could be achieved in the CCR1−/− mice with wild-type bone marrow cells, suggesting that these cells have a role in the response. However, transplanting of CCR1−/− bone marrow into wild-type mice did demonstrate an incomplete deficit in RSV-induced responses, indicating that CCR1+ parenchymal cells may also play a significant role in the process. Thus, the presence of CCR1 appears to have a significant role in the development of detrimental airway physiologic responses during RSV infection. These data suggest that CCR1 may be a potential target during detrimental pulmonary responses during infection.
Inhalation Tolerance Is Induced Selectively in Thoracic Lymph Nodes but Executed Pervasively at Distant Mucosal and Nonmucosal Tissues
Authors: Alvarez David , Swirski Filip K. , Yang Teng-Chih , Fattouh Ramzi , Croitoru Ken , Bramson Jonathan L. , Stämpfli Martin R. , Jordana Manel 
Published: April 2014

AbstractUnder immunogenic conditions, both the site of initial Ag exposure and consequent T cell priming in specific draining lymph nodes (LNs) imprint the ensuing immune response with lasting tissue-selective tropism. With respect to immune tolerance, whether the site of tolerance induction leads to compartmentalized or, alternatively, pervasive tolerance has not been formally investigated. Using a murine model of inhalation tolerance, we investigated whether the induction of respiratory mucosal tolerance precludes the development of de novo Th2 sensitization upon subsequent exposure to the same Ag at distant mucosal (gut) and nonmucosal (cutaneous) sites. By tracking the proliferation of CFSE-labeled OVA-TCR transgenic CD4+ T cells upon OVA inhalation in vivo, we defined the site of tolerance induction to be restricted to the thoracic LNs. Expectedly, inhalation tolerance prevented de novo Th2 sensitization upon subsequent exposure to the same Ag at the same site. Importantly, although gut- and skin-draining LNs were not used during tolerance induction, de novo Ag-specific proliferation and Th2 differentiation in these LNs, as well as memory/effector Th2 responses in the gut (allergic diarrhea) and skin (late-phase cutaneous responses) were inhibited upon immunogenic challenge to the same Ag. Interestingly, this pervasive tolerogenic phenotype was not associated with the presence of suppressive activity throughout the lymphatics; indeed, potent suppressive activity was detected solely in the spleen. These data indicate that while inhalation tolerance is selectively induced in local thoracic LNs, its tolerogenic activity resides systemically and leads to pervasive immune tolerance in distant mucosal and nonmucosal sites.
Epithelial CXCR3-B Regulates Chemokines Bioavailability in Normal, but Not in Sjögren’s Syndrome, Salivary Glands
Authors: Sfriso Paolo , Oliviero Francesca , Calabrese Fiorella , Miorin Marta , Facco Monica , Contri Antonella , Cabrelle Anna , Baesso Ilenia , Cozzi Franco , Andretta Marilisa , Cassatella Marco Antonio , Fiocco Ugo , Todesco Silvano , Konttinen Yrjö T. , Punzi Leonardo , Agostini Carlo 
Published: April 2014

Abstract
Expression of CXCR3-targeting chemokines have been demonstrated in several diseases, suggesting a critical role for CXCR3 in recruiting activated T cells to sites of immune-mediated inflammation. Sjögren’s syndrome (SS) is an autoimmune disease characterized by a mononuclear cell infiltrate of activated T cells around the duct in the salivary gland. Analysis of minor salivary gland biopsy specimens from 20 healthy subjects and 18 patients with primary SS demonstrated that CXCR3, in particular, the B form of this receptor, is constitutively expressed by human salivary gland epithelial cells. Salivary gland epithelial cell cultures demonstrated that CXCR3 participate in removing relevant amount of agonists from the supernatant of exposed cells without mediating calcium flux or chemotaxis while retaining the ability to undergo internalization. Although in normal salivary gland epithelial cells, CXCR3 behaves as a chemokine-scavenging receptor, its role in SS cells is functionally impaired. The impairment of this scavenging function might favor chemotaxis, leading to heightened immigration of CXCR3-positive T lymphocytes. These findings suggest that epithelial CXCR3 may be involved in postsecretion regulation of chemokine bioavailability. They also support a critical role for CXCR3 in the pathogenesis of SS and identify its agonists as potential therapeutic targets.
The Shaving Reaction: Rituximab/CD20 Complexes Are Removed from Mantle Cell Lymphoma and Chronic Lymphocytic Leukemia Cells by THP-1 Monocytes
Authors: Beum Paul V. , Kennedy Adam D. , Williams Michael E. , Lindorfer Margaret A. , Taylor Ronald P. 
Published: April 2014

Abstract
Clinical investigations have revealed that infusion of immunotherapeutic mAbs directed to normal or tumor cells can lead to loss of targeted epitopes, a phenomenon called antigenic modulation. Recently, we reported that rituximab treatment of chronic lymphocytic leukemia patients induced substantial loss of CD20 on B cells found in the circulation after rituximab infusion, when rituximab plasma concentrations were high. Such antigenic modulation can severely compromise therapeutic efficacy, and we postulated that B cells had been stripped (shaved) of the rituximab/CD20 complex by monocytes or macrophages in a reaction mediated by FcγR. We developed an in vitro model to replicate this in vivo shaving process, based on reacting rituximab-opsonized CD20+ cells with acceptor THP-1 monocytes. After 45 min at 37°C, rituximab and CD20 are removed from opsonized cells, and both are demonstrable on acceptor THP-1 cells. The reaction occurs equally well in the presence and absence of normal human serum, and monocytes isolated from peripheral blood also promote shaving of CD20 from rituximab-opsonized cells. Tests with inhibitors and use of F(ab′)2 of rituximab indicate transfer of rituximab/CD20 complexes to THP-1 cells is mediated by FcγR. Antigenic modulation described in previous reports may have been mediated by such shaving, and our findings may have profound implications for the use of mAbs in the immunotherapy of cancer.
Human NK Cells Positively Regulate γδ T Cells in Response to Mycobacterium tuberculosis
Authors: Zhang Ruijun , Zheng Xiaodong , Li Baiqing , Wei Haiming , Tian Zhigang 
Published: April 2014

Abstract
The decrease in NK cell activity and the loss of γδ T cells in active pulmonary tuberculosis patients have been reported. In this study, we observed that the proliferating response of γδ T cells to the heat-treated Ags of Mycobacterium tuberculosis from different individuals was noted to be dependent on the content or function of NK cells in PBMC in a population study. We also found that NK cells were directly rapidly activated by the heat-treated Ags from M. tuberculosis (H37Ra) in vitro; in turn, the activated NK cells improved γδ T cell proliferation both by CD54-mediated cell-cell contact through the forming immune synapse and by soluble factors TNF-α, GM-CSF, and IL-12, but not IFN-γ. Our results demonstrated that an interaction between NK cells and γδ T cells existed in antituberculosis immunity. Up-regulating the function of NK cells might be beneficial to the prevention and control of pulmonary tuberculosis.
Tolerance Induction by Transcutaneous Immunization through Ultraviolet-Irradiated Skin Is Transferable through CD4+CD25+ T Regulatory Cells and Is Dependent on Host-Derived IL-10
Authors: Ghoreishi Mehran , Dutz Jan P. 
Published: April 2014

Abstract
UV radiation of the skin impairs immune responses to haptens and to tumor Ags. Transcutaneous immunization (TCI) is an effective method of inducing immune responses to protein and peptide Ag. We explore the effect of UV irradiation on TCI. The generation of Ag-specific CTL to OVA protein, but not class I MHC-restricted OVA peptide, is inhibited by TCI through UV-irradiated skin. Consequently, the induction of protein contact hypersensitivity and in vivo Ag-specific CTL activity following OVA protein immunization is prevented. Application of haptens to UV-exposed skin induces hapten-specific tolerance. We demonstrate that application of protein or class II MHC-restricted OVA peptide to UV-irradiated skin induces transferable Ag-specific tolerance. This tolerance is mediated by CD4+CD25+ T regulatory (Treg) cells. These Ag-specific Treg cells inhibit the priming of CTL following protein immunization in the presence of CpG adjuvant. IL-10 deficiency is known to prevent hapten-specific tolerance induction. In this study, we demonstrate, using IL-10-deficient mice and adoptive T cell transfer, that IL-10 is required for the direct inhibition of CTL priming following immunization through UV-irradiated skin. However, IL-10 is not required for the induction of Treg cells through UV-irradiated skin as IL-10-deficient Treg cells are able to mediate tolerance. Rather, host-derived IL-10 is required for the function of UV-generated Treg cells. These experiments indicate that protein and peptide TCI through UV-irradiated skin may be used to induce robust Ag-specific tolerance to neo-Ags and that UV-induced Treg cells mediate their effects in part through the modulation of IL-10.
Longitudinal Studies of Clonally Expanded CD8 T Cells Reveal a Repertoire Shrinkage Predicting Mortality and an Increased Number of Dysfunctional Cytomegalovirus-Specific T Cells in the Very Elderly
Authors: Hadrup Sine Reker , Strindhall Jan , Køllgaard Tania , Seremet Tina , Johansson Boo , Pawelec Graham , thor Straten Per , Wikby Anders 
Published: April 2014

Abstract
The age-associated decrease in functionality of the human immune system is thought to have a negative impact on the capacity to provide protection against infection, in turn leading to increased incidence of mortality. In a previous longitudinal study of octogenarians, we identified an immune risk phenotype (IRP) in the very elderly defined by an inverted CD4/CD8 ratio, which was associated with increased mortality and persistent CMV infection. In this study, we analyzed the CD8 clonal composition of nonagenarians and middle-aged individuals. An increased number of CD8 T cell clones was observed in the nonagenarians, and was associated with CMV-seropositivity. Surprisingly, CMV-seropositive nonagenarians with the IRP had a significantly lower number of clones compared with non-IRP individuals. The decrease in clone numbers in IRP individuals was associated with shorter survival time. MHC/peptide multimer staining indicated that the frequency of CMV-specific T cells was higher in nonagenarians than in the middle-aged, but the ratio of functionally intact cells was significantly lower. The lowest ratio of functional CMV-specific T cells was found in an IRP individual. A thorough longitudinal analysis of the CMV-specific T cells in nonagenarians showed a stable pattern with respect to frequency, phenotype, and clonal composition. We hypothesize that the number of different CD8 T cell clonal expansions increases as the individual ages, possibly, as a compensatory mechanism to control latent infections, e.g., CMV, but eventually a point is reached where clonal exhaustion leads to shrinkage of the CD8 clonal repertoire, associated with decreased survival.