bluuebunny/crossref_metadata_2025_split huggingface dataset:
HIV-1 Tat-Mediated Effects on Focal Adhesion Assembly and Permeability in Brain Microvascular Endothelial Cells
Authors: Avraham Hava Karsenty , Jiang Shuxian , Lee Tae-Hee , Prakash Om , Avraham Shalom 
Published: April 2014

Abstract
The blood-brain barrier (BBB) is a network formed mainly by brain microvascular endothelial cells (BMECs). The integrity of the BBB is critical for brain function. Breakdown of the BBB is commonly seen in AIDS patients with HIV-1-associated dementia despite the lack of productive HIV infection of the brain endothelium. The processes by which HIV causes these pathological conditions are not well understood. In this study we characterized the molecular mechanisms by which Tat mediates its pathogenic effects in vitro on primary human BMECs (HBMECs). Tat treatment of HBMECs stimulated cytoskeletal organization and increased focal adhesion sites compared with control cells or cells treated with heat-inactivated Tat. Pretreatment with Tat Abs or with the specific inhibitor SU-1498, which interferes with vascular endothelial growth factor receptor type 2 (Flk-1/KDR) phosphorylation, blocked the ability of Tat to stimulate focal adhesion assembly and the migration of HBMECs. Focal adhesion kinase (FAK) was tyrosine-phosphorylated by Tat and was found to be an important component of focal adhesion sites. Inhibition of FAK by the dominant interfering mutant form, FAK-related nonkinase, significantly blocked HBMEC migration and disrupted focal adhesions upon Tat activation. Furthermore, HIV-Tat induced permeability changes in HBMECs in a time-dependent manner. Tat also impaired BBB permeability, as observed in HIV-1 Tat transgenic mice. These studies define a mechanism for HIV-1 Tat in focal adhesion complex assembly in HBMECs via activation of FAK, leading to cytoskeletal reorganization and permeability changes.
Enhancer Role of STAT5 in CD2 Activation of IFN-γ Gene Expression
Authors: Gonsky Rivkah , Deem Richard L. , Bream Jay , Young Howard A. , Targan Stephan R. 
Published: April 2014

AbstractIFN-γ is an important immunoregulatory protein with tightly controlled expression in activated T and NK cells. Three potential STAT binding regions have been recognized within the IFN-γ promoter: 1) an IL-12-mediated STAT4 binding site at −236 bp; 2) a newly identified IL-2-induced STAT5 binding element at −3.6 kb; and 3) CD2-mediated STAT1 and STAT4 binding to an intronic element in mucosal T cells. However, functional activation of these sites remains unclear. In this study we demonstrate CD2-mediated activation of the newly characterized −3.6-kb IFN-γ STAT5 binding region. CD2 signaling of human PBMC results in activation of the −3.6-kb IFN-γ promoter, whereas mutation of the −3.6-kb STAT5 site attenuates promoter activity. Functional activation is accompanied by STAT5A but little STAT5B nucleoprotein binding to the IFN-γ STAT5 site, as determined by competition and supershift assays. STAT5 activation via CD2 occurs independent of IL-2. Western and FACS analysis shows increased phospho-STAT5 following CD2 signaling. AG490, a tyrosine kinase inhibitor affecting Jak proteins, inhibits CD2-mediated IFN-γ mRNA expression, secretion, and nucleoprotein binding to the IFN-γ STAT5 site in a dose-dependent fashion. This report is the first to describe CD2-mediated activation of STAT5 and supports STAT5 involvement in regulation of IFN-γ expression.
Involvement of FcγR I (CD64) in the Mechanism of HIV-1 Inhibition by Polyclonal IgG Purified from Infected Patients in Cultured Monocyte-Derived Macrophages
Authors: Holl Vincent , Hemmerter Stéphane , Burrer Renaud , Schmidt Sylvie , Bohbot Alain , Aubertin Anne-Marie , Moog Christiane 
Published: April 2014

Abstract
The aim of this study was to investigate the mechanism of HIV-1 neutralization using monocyte-derived macrophages (MDM) in comparison to PBMC as target cells. For this purpose, we analyzed neutralizing activities of different human polyclonal IgG samples purified from sera of HIV-1-infected individuals using a single cycle infection assay. We found an increase of the neutralizing titer when macrophages vs PBMC were used as target cells. Moreover, polyclonal IgG from HIV-1-infected patients that are not able to neutralize virus when PBMC are used as target cells strongly inhibit MDM infection. Similar results were obtained with neutralizing mAbs. To explore the participation of FcγRs in HIV-1 inhibition, F(ab′)2 and Fab of these Igs were produced. Results indicated that both F(ab′)2 and Fab are less effective to inhibit virus replication in MDM. Moreover, competition experiments with Fc fragments of IgG from healthy donors or with purified monoclonal anti-human FcγRs Ab strengthen the participation of the FcγRs, and in particular of FcγRI (CD64) in HIV-1 inhibition on MDM. Mechanisms by which HIV-specific IgG inhibit virus replication in cultured macrophages are proposed and the benefit of inducing such Abs by vaccination is discussed.
Pathogen-Induced Apoptotic Neutrophils Express Heat Shock Proteins and Elicit Activation of Human Macrophages
Authors: Zheng Limin , He Min , Long Min , Blomgran Robert , Stendahl Olle 
Published: April 2014

AbstractIngestion of aged or irradiated apoptotic neutrophils actively suppresses stimulation of macrophages (Mφ). Many bacterial pathogens can also provoke apoptosis in neutrophils, but little is known about how such apoptotic cells influence Mφ activation. We found that neutrophils undergoing apoptosis induced by UV irradiation, Escherichia coli, or Staphylococcus aureus could either stimulate or inhibit Mφ activation. In contrast to Mφ that had ingested irradiated apoptotic neutrophils, Mφ that had phagocytosed bacteria-induced apoptotic neutrophils exhibited markedly increased production of the proinflammatory cytokine TNF-α, but not the anti-inflammatory cytokine TGF-β. Moreover, ingestion of bacteria, but not UV-induced apoptotic neutrophils, caused increased expression of FcγRI on Mφ, and this effect was not provoked directly by bacteria associated with the apoptotic neutrophils. Instead, we found that a link between pathogen-induced apoptotic neutrophils and up-regulation of the heat shock proteins HSP60 and HSP70, and we also observed that recombinant HSP60 and HSP70 potentiated LPS-stimulated production of TNF-α in Mφ. The opposing macrophage responses to neutrophils undergoing apoptosis induced in different ways may represent a novel mechanism that regulates the extent of the immune response to invading microbes in two steps: first by aiding the functions of Mφ at an early stage of infection, and subsequently by deactivating those cells through removal of uninfected apoptotic neutrophils. HSP induction in neutrophils may provide the danger signals required to generate a more effective macrophage response.
Hematopoietic Cells Are Required to Initiate a Chlamydia trachomatis-Specific CD8+ T Cell Response
Authors: Steele Lisa N. , Balsara Zarine R. , Starnbach Michael N. 
Published: April 2014

Abstract
Chlamydia trachomatis is a global human pathogen causing diseases ranging from blinding trachoma to pelvic inflammatory disease. To explore how innate and adaptive immune responses cooperate to protect against systemic infection with C. trachomatis L2, we investigated the role of macrophages (Mφ) and dendritic cells (DCs) in the stimulation of C. trachomatis-specific CD8+ T cells. We found that C. trachomatis infection of Mφ and DCs is far less productive than infection of nonprofessional APCs, the typical targets of infection. However, despite the limited replication of C. trachomatis within Mφ and DCs, infected Mφ and DCs process and present C. trachomatis CD8+ T cell Ag in a proteasome-dependent manner. These findings suggest that although C. trachomatis is a vacuolar pathogen, some Ags expressed in infected Mφ and DCs are processed in the host cell cytosol for presentation to CD8+ T cells. We also show that even though C. trachomatis replicates efficiently within nonprofessional APCs both in vitro and in vivo, Ag presentation by hematopoietic cells is essential for initial stimulation of C. trachomatis-specific CD8+ T cells. However, when DCs infected with C. trachomatis ex vivo were adoptively transferred into naive mice, they failed to prime C. trachomatis-specific CD8+ T cells. We propose a model for priming C. trachomatis-specific CD8+ T cells whereby DCs acquire C. trachomatis Ag by engulfing productively infected nonprofessional APCs and then present the Ag to T cells via a mechanism of cross-presentation.
Single Mucosal, but Not Parenteral, Immunization with Recombinant Adenoviral-Based Vaccine Provides Potent Protection from Pulmonary Tuberculosis
Authors: Wang Jun , Thorson Lisa , Stokes Richard W. , Santosuosso Michael , Huygen Kris , Zganiacz Anna , Hitt Mary , Xing Zhou 
Published: April 2014

Abstract
Bacillus Calmette-Guérin (BCG) vaccine has failed to control the global tuberculosis (TB) epidemic, and there is a lack of safe and effective mucosal vaccines capable of potent protection against pulmonary TB. A recombinant replication-deficient adenoviral-based vaccine expressing an immunogenic Mycobacterium tuberculosis Ag Ag85A (AdAg85A) was engineered and evaluated for its potential to be used as a respiratory mucosal TB vaccine in a murine model of pulmonary TB. A single intranasal, but not i.m., immunization with AdAg85A provided potent protection against airway Mycobacterium tuberculosis challenge at an improved level over that by cutaneous BCG vaccination. Systemic priming with an Ag85A DNA vaccine and mucosal boosting with AdAg85A conferred a further enhanced immune protection which was remarkably better than BCG vaccination. Such superior protection triggered by AdAg85 mucosal immunization was correlated with much greater retention of Ag-specific T cells, particularly CD4 T cells, in the lung and was shown to be mediated by both CD4 and CD8 T cells. Thus, adenoviral TB vaccine represents a promising novel vaccine platform capable of potent mucosal immune protection against TB. Our study also lends strong evidence that respiratory mucosal vaccination is critically advantageous over systemic routes of vaccination against TB.
A Novel Role of Cysteinyl Leukotrienes to Promote Dendritic Cell Activation in the Antigen-Induced Immune Responses in the Lung
Authors: Okunishi Katsuhide , Dohi Makoto , Nakagome Kazuyuki , Tanaka Ryoichi , Yamamoto Kazuhiko 
Published: April 2014

Abstract
Although the critical role of cysteinyl leukotrienes (cysLTs) in the inflammation, especially eosinophilic lung inflammation, in asthma has been well documented, their role in the early stage of Ag-specific immune response has not been completely clarified. In the present study, with a mouse model of asthma and in vitro studies we demonstrated that cysLTs potentiated dendritic cell (DC) functions such as Ag-presenting capacity and cytokine production. The cysLT-1 receptor antagonist (LTRA) strongly suppressed the activation of these DC functions and led to inhibition of subsequent not only Th2, but also Th1, responses in the early stage of immune response. Moreover, treatment with LTRA during the early stage of the immune response potently suppressed the development of Ag inhalation-induced eosinophilic airway inflammation, mucus production, and airway hyper-reactivity in vivo. Treatment with LTRA significantly increased PGE2 production in the lung, and treatment with the cyclooxygenase inhibitor indomethacin abolished LTRA’s suppressive effect on DCs and deteriorated the Th2 and Th1 responses and airway inflammation. With in vitro studies, we also confirmed that cysLTs production by DCs increased with LPS stimulation, and that LTRA directly suppressed the alloantigen-presenting capacity of DCs. These results suggested that cysLTs potentiate DC functions both in vivo and in vitro, and that LTRA could be beneficial to suppress the initial immune response in many immune-mediated disorders beyond asthma.
Regulation and Function of Cyclin D2 in B Lymphocyte Subsets
Authors: Chiles Thomas C. 
Published: April 2014

AbstractAbs produced by B lymphocytes play an essential role in humoral immunity against pathogens. This response is dependent upon the extent of genome replication, which in turn allows clonal expansion of Ag-specific B cell precursors. Thus, there is considerable interest in understanding how naive B cells commit to genome replication following Ag challenge. The BCR is a key regulator of B cell growth responses in the bone marrow and the periphery. The importance of identifying BCR-coupled signaling networks and their cell cycle targets is underscored by the recognition that aberrant cell cycle control can lead to lymphoproliferative disorders or lymphoid malignancies. This review focuses on recent progress toward understanding the function of cyclin D2 in cell cycle control, and in the development of murine B lymphocytes.
Cutting Edge: 1,25-Dihydroxyvitamin D3 Is a Direct Inducer of Antimicrobial Peptide Gene Expression
Authors: Wang Tian-Tian , Nestel Frederick P. , Bourdeau Véronique , Nagai Yoshihiko , Wang Qiuyu , Liao Jie , Tavera-Mendoza Luz , Lin Roberto , Hanrahan John W. , Mader Sylvie , White John H. 
Published: April 2014

Abstract
The hormonal form of vitamin D3, 1,25-dihydroxyvitamin D3 (1,25(OH)2D3), is an immune system modulator and induces expression of the TLR coreceptor CD14. 1,25(OH)2D3 signals through the vitamin D receptor, a ligand-stimulated transcription factor that recognizes specific DNA sequences called vitamin D response elements. In this study, we show that 1,25(OH)2D3 is a direct regulator of antimicrobial innate immune responses. The promoters of the human cathelicidin antimicrobial peptide (camp) and defensin β2 (defB2) genes contain consensus vitamin D response elements that mediate 1,25(OH)2D3-dependent gene expression. 1,25(OH)2D3 induces antimicrobial peptide gene expression in isolated human keratinocytes, monocytes and neutrophils, and human cell lines, and 1,25(OH)2D3 along with LPS synergistically induce camp expression in neutrophils. Moreover, 1,25(OH)2D3 induces corresponding increases in antimicrobial proteins and secretion of antimicrobial activity against pathogens including Pseudomonas aeruginosa. 1,25(OH)2D3 thus directly regulates antimicrobial peptide gene expression, revealing the potential of its analogues in treatment of opportunistic infections.
Cutting Edge: TNFR-Associated Factor (TRAF) 6 Is Essential for MyD88-Dependent Pathway but Not Toll/IL-1 Receptor Domain-Containing Adaptor-Inducing IFN-β (TRIF)-Dependent Pathway in TLR Signaling
Authors: Gohda Jin , Matsumura Takayuki , Inoue Jun-ichiro 
Published: April 2014

Abstract
Signaling pathways from TLRs are mediated by the Toll/IL-1R (TIR) domain-containing adaptor molecules. TNF receptor-associated factor (TRAF) 6 is thought to activate NF-κB and MAPKs downstream of these TIR domain-containing proteins to induce production of inflammatory cytokines. However, the precise role of TRAF6 in signaling from individual TLRs has not been appropriately addressed. We analyzed macrophages from TRAF6-deficient mice and made the following observations. In the absence of TRAF6, 1) ligands for TLR2, TLR5, TLR7, and TLR9 failed to induce activation of NF-κB and MAPKs or production of inflammatory cytokines; 2) TLR4 ligand-induced cytokine production was remarkably reduced and activation of NF-κB and MAPKs was observed, albeit with delayed kinetics; and 3) in contrast with previously reported findings, TLR3 signaling was not affected. These results indicate that TRAF6 is essential for MyD88-dependent signaling but is not required for TIR domain-containing adaptor-inducing IFN-β (TRIF)-dependent signaling.
Cutting Edge: Regulation of CD8+ T Cell Effector Population Size
Authors: Kemp Roslyn A. , Powell Timothy J. , Dwyer David W. , Dutton Richard W. 
Published: April 2014

Abstract
Naive CD8+ T cells are activated on encounter with Ag presented on dendritic cells and proliferate rapidly. To investigate the regulation of naive CD8+ T cells proliferation, we adoptively transferred TCR-transgenic CD8+ T cells into intact mice together with Ag-pulsed dendritic cells. Regardless of the number of cells initially transferred, the expansion of activated Ag-specific CD8+ T cells was limited to a ceiling of effector cells. This limit was reached from a wide range of T cell doses, including a physiological number of precursor cells, and was not altered by changing the amount of Ag or APCs. The total Ag-specific response was composed of similar numbers of host and donor transgenic cells regardless of donor cell input, suggesting that these populations were independently regulated. Regulation of the transgenic donor cell population was TCR specific. We hypothesize that a clone-specific regulatory mechanism controls the extent of CD8+ T cell responses to Ag.
Presumptive Lymph Node Organizers are Differentially Represented in Developing Mesenteric and Peripheral Nodes
Authors: Cupedo Tom , Vondenhoff Mark F. R. , Heeregrave Edwin J. , de Weerd Anna E. , Jansen Wendy , Jackson David G. , Kraal Georg , Mebius Reina E. 
Published: April 2014

Abstract
During murine embryogenesis, the formation of Peyer’s patches (PPs) is initiated by CD45+CD4+CD3− lymphoid tissue inducers that trigger adhesion molecule expression and specific chemokine production from an organizing stromal cell population through ligation of the lymphotoxin-β receptor. However, the steps involved in the development of lymph nodes (LNs) are less clear than those of PPs, and the characteristics of the organizing cells within the LN anlagen have yet to be documented. In this study, we show for the first time that the early anlage is bordered by an endothelial layer that retains a mixed lymphatic and blood vascular phenotype up to embryonic day 16.5. This in turn encompasses CD45+CD4+CD3− cells interspersed with ICAM-1/VCAM-1/mucosal addressin cell adhesion molecule-1, lymphotoxin-β receptor-positive, chemokine-producing cells analogous to the organizing population previously observed in PPs. Moreover, these LN organizers also express the TNF family member, TRANCE. Lastly, we show that the ICAM-1/VCAM-1/mucosal addressin cell adhesion molecule-1 cells present in peripheral and mesenteric LN form two discrete populations expressing either intermediate or high levels of these adhesion molecules but that the former population is specifically reduced in PLN. These findings provide a possible explanation for the well-known differences in developmental requirements for nodes at peripheral or mesenteric locations.
A Novel Mutation in CD83 Results in the Development of a Unique Population of CD4+ T Cells
Authors: García-Martínez Leon F. , Appleby Mark W. , Staehling-Hampton Karen , Andrews Dawn M. , Chen Yuching , McEuen Mark , Tang Phuong , Rhinehart Rebecca L. , Proll Sean , Paeper Bryan , Brunkow Mary E. , Grandea Andres G. , Howard Edward D. , Walker Don E. , Charmley Patrick , Jonas Mechthild , Shaw Stevan , Latham John A. , Ramsdell Fred 
Published: April 2014

Abstract
Using a mouse mutagenesis screen, we have identified CD83 as being critical for the development of CD4+ T cells and for their function postactivation. CD11c+ dendritic cells develop and function normally in mice with a mutated CD83 gene but CD4+ T cell development is substantially reduced. Additionally, we now show that those CD4+ cells that develop in a CD83 mutant animal fail to respond normally following allogeneic stimulation. This is at least in part due to an altered cytokine expression pattern characterized by an increased production of IL-4 and IL-10 and diminished IL-2 production. Thus, in addition to its role in selection of CD4+ T cells, absence of CD83 results in the generation of cells with an altered activation and cytokine profile.
4-1BB and OX40 Dual Costimulation Synergistically Stimulate Primary Specific CD8 T Cells for Robust Effector Function
Authors: Lee Seung-Joo , Myers Lara , Muralimohan Guruprasaadh , Dai Jie , Qiao Yi , Li Zihai , Mittler Robert S. , Vella Anthony T. 
Published: April 2014

AbstractCD40, 4-1BB, and OX40 are costimulatory molecules belonging to the TNF/nerve growth factor superfamily of receptors. We examined whether simultaneous costimulation affected the responses of T cells using several different in vivo tracking models in mice. We show that enforced dual costimulation through 4-1BB and OX40, but not through CD40, induced profound specific CD8 T cell clonal expansion. In contrast, the response of specific CD4 T cells to dual costimulation was additive rather than synergistic. The synergistic response of the specific CD8 T cells persevered for several weeks, and the expanded effector cells resided throughout lymphoid and nonlymphoid tissue. Dual costimulation through 4-1BB and OX40 did not increase BrdU incorporation nor an increase in the number of rounds of T cell division in comparison to single costimulators, but rather enhanced accumulation in a cell-intrinsic manner. Mechanistically speaking, we show that CD8 T cell clonal expansion and effector function did not require T help, but accumulation in (non)lymphoid tissue was predominantly CD4 T cell dependent. To determine whether this approach would be useful in a physiological setting, we demonstrated that dual costimulation mediated rejection of an established murine sarcoma. Importantly, effector function directed toward established tumors was CD8 T cell dependent while being entirely CD4 T cell independent, and the timing of enforced dual costimulation was exquisitely regulated. Collectively, these data suggest that simultaneous dual costimulation through 4-1BB and OX40 induces a massive burst of CD8 T cell effector function sufficient to therapeutically treat established tumors even under immunocompromising conditions.
Vascular Endothelium Does Not Activate CD4+ Direct Allorecognition in Graft Rejection
Authors: Kreisel Daniel , Krasinskas Alyssa M. , Krupnick Alexander S. , Gelman Andrew E. , Balsara Keki R. , Popma Sicco H. , Riha Markus , Rosengard Ariella M. , Turka Laurence A. , Rosengard Bruce R. 
Published: April 2014

AbstractExpression of MHC class II by donor-derived APCs has been shown to be important for allograft rejection. It remains controversial, however, whether nonhemopoietic cells, such as vascular endothelium, possess Ag-presenting capacity to activate alloreactive CD4+ T lymphocytes. This issue is important in transplantation, because, unlike hemopoietic APCs, allogeneic vascular endothelium remains present for the life of the organ. In this study we report that cytokine-activated vascular endothelial cells are poor APCs for allogeneic CD4+ T lymphocytes in vitro and in vivo despite surface expression of MHC class II. Our in vitro observations were extended to an in vivo model of allograft rejection. We have separated the allostimulatory capacity of endothelium from that of hemopoietic APCs by using bone marrow chimeras. Hearts that express MHC class II on hemopoietic APCs are acutely rejected in a mean of 7 days regardless of the expression of MHC class II on graft endothelium. Alternatively, hearts that lack MHC class II on hemopoietic APCs are acutely rejected at a significantly delayed tempo regardless of the expression of MHC class II on graft endothelium. Our data suggest that vascular endothelium does not play an important role in CD4+ direct allorecognition and thus does not contribute to the vigor of acute rejection.