bluuebunny/crossref_metadata_2025_split huggingface dataset:
Induction of Apoptosis in Human T Cells by Actinobacillus actinomycetemcomitans Cytolethal Distending Toxin Is a Consequence of G2 Arrest of the Cell Cycle
Authors: Shenker Bruce J. , Hoffmaster Roselle H. , Zekavat Ali , Yamaguchi Noboru , Lally Edward T. , Demuth Donald R. 
Published: April 2014

Abstract
We have previously shown that Actinobacillus actinomycetemcomitans produces an immunosuppressive factor that is encoded by the cdtB gene, which is homologous to a family of cytolethal distending toxins (Cdt) expressed by several Gram-negative bacteria. Moreover, we have shown that CdtB impairs lymphocyte function by inducing G2 arrest of the cell cycle. We now report that both CdtB as well as an extract prepared from an Escherichia coli strain that expresses all three of the A. actinomycetemcomitans cdt genes (rCdtABC) induce apoptosis. Pretreatment of lymphocytes with either CdtB or rCdtABC leads to DNA fragmentation in activated lymphocytes at 72 and 96 h. No DNA fragmentation was induced in nonactivated cells. Flow cytometric analysis of the Cdt-treated lymphocytes demonstrates a reduction in cell size and an increase in nuclear condensation. Mitochondrial function was also perturbed in cells pretreated with either CdtB or rCdtABC. An increase in the expression of the mitochondria Ag, Apo 2.7, was observed along with evidence of the development of a mitochondrial permeability transition state; this includes a decrease in the transmembrane potential and elevated generation of reactive oxygen species. Activation of the caspase cascade, which is an important biochemical feature of the apoptotic process, was also observed in Cdt-treated lymphocytes. Overexpression of the bcl-2 gene in the human B lymphoblastoid cell line, JY, led to a decrease in Cdt-induced apoptosis. Interestingly, Bcl-2 overexpression did not block Cdt-induced G2 arrest. The implications of our results with respect to the immunosuppressive functions of Cdt proteins are discussed.
Role of Mitogen-Activated Protein Kinase-Mediated Cytosolic Phospholipase A2 Activation in Arachidonic Acid Metabolism in Human Eosinophils
Authors: Zhu Xiangdong , Sano Hiroyuki , Kim Kwang Pyo , Sano Akiko , Boetticher Evan , Muñoz Nilda M. , Cho Wonhwa , Leff Alan R. 
Published: April 2014

Abstract
The objective of this investigation was to determine the role of secretory and cytosolic isoforms of phospholipase A2 (PLA2) in the induction of arachidonic acid (AA) and leukotriene synthesis in human eosinophils and the mechanism of PLA2 activation by mitogen-activated protein kinase (MAPK) isoforms in this process. Pharmacological activation of eosinophils with fMLP caused increased AA release in a concentration (EC50 = 8.5 nM)- and time-dependent (t1/2 = 3.5 min) manner. Both fMLP-induced AA release and leukotriene C4 (LTC4) secretion were inhibited concentration dependently by arachidonic trifluoromethyl ketone, a cytosolic PLA2 (cPLA2) inhibitor; however, inhibition of neither the 14-kDa secretory phospholipase A2 by 3-(3-acetamide-1-benzyl-2-ethylindolyl-5-oxy)propanephosphonic acid nor cytosolic Ca2+-independent phospholipase A2 inhibition by bromoenol lactone blocked hydrolysis of AA or subsequent leukotriene synthesis. Pretreatment of eosinophils with a mitogen-activated protein/extracellular signal-regulated protein kinase (ERK) kinase inhibitor, U0126, or a p38 MAPK inhibitor, SB203580, suppressed both AA production and LTC4 release. fMLP induced phosphorylation of MAPK isoforms, ERK1/2 and p38, which were evident after 30 s, maximal at 1–5 min, and declined thereafter. fMLP stimulation also increased cPLA2 activity in eosinophils, which was inhibited completely by 30 μM arachidonic trifluoromethyl ketone. Preincubation of eosinophils with U0126 or SB203580 blocked fMLP-enhanced cPLA2 activity. Furthermore, inhibition of Ras, an upstream GTP-binding protein of ERK, also suppressed fMLP-stimulated AA release. These findings demonstrate that cPLA2 activation causes AA hydrolysis and LTC4 secretion. We also find that cPLA2 activation caused by fMLP occurs subsequent to and is dependent upon ERK1/2 and p38 MAPK activation. Other PLA2 isoforms native to human eosinophils possess no significant activity in the stimulated production of AA or LTC4.
Diphosphoryl Lipid A from Rhodobacter sphaeroides Blocks the Binding and Internalization of Lipopolysaccharide in RAW 264.7 Cells
Authors: Kutuzova Galina D. , Albrecht Ralph M. , Erickson Chris M. , Qureshi Nilofer 
Published: April 2014

Abstract
Diphosphoryl lipid A derived from the nontoxic LPS of Rhodobacter sphaeroides (RsDPLA) has been shown to be a powerful LPS antagonist in both human and murine cell lines. In addition, RsDPLA also can protect mice against the lethal effects of toxic LPS. In this study, we complexed both the deep rough LPS from Escherichia coli D31 m4 (ReLPS) and RsDPLA with 5- and 30-nm colloidal gold and compared their binding to the RAW 264.7 cell line by electron microscopy. Both ReLPS and RsDPLA bound to the cells with the following observations. First, binding studies revealed that pretreatment with RsDPLA completely blocked the binding and thus internalization of ReLPS-gold conjugates to these cells at both 37°C and 4°C. Second, ReLPS was internalized via micropinocytosis (noncoated plasma membrane invaginations) involving formation of caveolae-like structures and leading to the formation of micropinocytotic vesicles, macropinocytosis (or phagocytosis), formation of clathrin-coated pits (receptor mediated), and penetration through plasma membrane into cytoplasm. Third, in contrast, RsDPLA was internalized predominantly via macropinocytosis. These studies show for the first time that RsDPLA blocks the binding and thus internalization of LPS as observed by scanning and transmission electron microscopy.
Gammalinolenic Acid, an Unsaturated Fatty Acid with Anti-Inflammatory Properties, Blocks Amplification of IL-1β Production by Human Monocytes
Authors: Furse Robert K. , Rossetti Ronald G. , Zurier Robert B. 
Published: April 2014

Abstract
Administration of gammalinolenic acid (GLA), an unsaturated fatty acid, reduces joint inflammation in patients with rheumatoid arthritis. Addition of GLA in vitro suppresses release of IL-1β from human monocytes stimulated with LPS. LPS-induced IL-1β release is followed by IL-1-induced IL-1β release, an amplification process termed autoinduction. We show here with peripheral blood monocytes from normal volunteers and from patients with rheumatoid arthritis by using IL-1R antagonist to block autoinduction and IL-1α stimulation to simulate autoinduction that ∼40% of IL-1β released from LPS-stimulated cells is attributable to autoinduction and that GLA reduces autoinduction of IL-1β while leaving the initial IL-1β response to LPS intact. Experiments with cells in which transcription and protein synthesis were blocked suggest that GLA induces a protein that reduces pro-IL-1β mRNA stability. IL-1β is important to host defense, but the amplification mechanism may be excessive in genetically predisposed patients. Thus, reduction of IL-1β autoinduction may be protective in some patients with endotoxic shock and with diseases characterized by chronic inflammation.
Both E6 and E7 Oncoproteins of Human Papillomavirus 16 Inhibit IL-18-Induced IFN-γ Production in Human Peripheral Blood Mononuclear and NK Cells
Authors: Lee Shin-Je , Cho Young-Sik , Cho Min-Chul , Shim Jung-Hyun , Lee Kyung-Ae , Ko Kwang-Kjune , Choe Yong Kyung , Park Sue-Nie , Hoshino Tomoaki , Kim SooHyun , Dinarello Charles A. , Yoon Do-Young 
Published: April 2014

Abstract
Cervical carcinoma is the predominant cancer among malignancies in women throughout the world, and human papillomavirus (HPV) 16 is the most common agent linked to human cervical carcinoma. The present study was performed to investigate the mechanisms of immune escape in HPV-induced cervical cancer cells. The presence of HPV oncoproteins E6 and E7 in the extracellular fluids of HPV-containing cervical cancer cell lines SiHa and CaSki was demonstrated by ELISA. The effect of HPV 16 oncoproteins E6 and E7 on the production of IFN-γ by IL-18 was assessed. E6 and E7 proteins reduced IL-18-induced IFN-γ production in both primary PBMCs and the NK0 cell line. FACS analysis revealed that the viral oncoproteins reduced the binding of IL-18 to its cellular surface receptors on NK0 cells, whereas there was no effect of oncoproteins on IL-1 binding to its surface IL-1 receptors on D10S, a subclone of the murine Th cell D10.G4.1. In vitro pull-down assays also revealed that the viral oncoproteins and IL-18 bound to IL-18R α-chain competitively. These results suggest that the extracellular HPV 16 E6 and E7 proteins may inhibit IL-18-induced IFN-γ production locally in HPV lesions through inhibition of IL-18 binding to its α-chain receptor. Down-modulation of IL-18-induced immune responses by HPV oncoproteins may contribute to viral pathogenesis or carcinogenesis.
Estrogen Treatment Down-Regulates TNF-α Production and Reduces the Severity of Experimental Autoimmune Encephalomyelitis in Cytokine Knockout Mice
Authors: Ito Atsushi , Bebo Bruce F. , Matejuk Agata , Zamora Alex , Silverman Marc , Fyfe-Johnson Amber , Offner Halina 
Published: April 2014

AbstractA shift toward Th2 cytokine production has been demonstrated during pregnancy and high dose estrogen therapy and is thought to be the primary mechanism by which estrogen suppresses the development of experimental autoimmune encephalomyelitis. However, low dose estrogen treatment is equally protective in the absence of a significant shift in cytokine production. In this study cytokine-deficient mice were treated with estrogen to determine whether a shift in Th2 cytokine production was required for the protective effects of hormone therapy. Estrogen effectively suppressed the development of experimental autoimmune encephalomyelitis in IL-4 and IL-10 knockout mice and in wild type littermate mice with a similar potency of protection. Significant disease suppression was also seen in IFN-γ-deficient mice. The decrease in disease severity was accompanied by a concomitant reduction in the number of proinflammatory cytokine- and chemokine-producing cells in the CNS. Although there was no apparent increase in compensatory Th2 cytokine production in cytokine-deficient mice, there was a profound decrease in the frequency of TNF-α-producing cells in the CNS and the periphery. Therefore, we propose that one mechanism by which estrogen protects females from the development of cell-mediated autoimmunity is through a hormone-dependent regulation of TNF-α production.
Suppression of IL-2-Induced T Cell Proliferation and Phosphorylation of STAT3 and STAT5 by Tumor-Derived TGFβ Is Reversed by IL-15
Authors: Campbell John D. M. , Cook Gordon , Robertson Susan E. , Fraser Alasdair , Boyd Kelly S. , Gracie J. Alastair , Franklin Ian M. 
Published: April 2014

Abstract
IL-2 responses are susceptible to suppression by TGFβ, a cytokine widely implicated in suppression of inflammatory responses and secreted by many different tumor cell types. There have been conflicting reports regarding inhibition of IL-2-induced STAT3 and STAT5 phosphorylation by TGFβ and subsequent suppression of immune responses. Using TGFβ-producing multiple myeloma tumor cells we demonstrate that tumor-derived TGFβ can block IL-2-induced proliferation and STAT3 and STAT5 phosphorylation in T cells. High affinity IL-2R expression was required for the suppression of IL-2 responses as a novel CD25− T cell line proliferated and phosphorylated STAT3 when cultured with tumor cells or rTGFβ1. Activating T cells with IL-15, which does not use the high affinity IL-2R, completely restored the ability of T cells to phosphorylate STAT3 and STAT5 when cultured with tumor cells. IL-15-treated T cells proliferated normally when cocultured with tumor cells or rTGFβ1, whereas IL-2 responses were consistently inhibited. Preincubation with IL-15 also restored the ability of T cells to respond to IL-2 by phosphorylating STAT3 and STAT5, and proliferating normally in the presence of tumor cells. IL-2 pretreatment did not restore T cell function. IL-15 also restored T cell responses by T cells from multiple myeloma patients, and against freshly isolated bone marrow tumor samples. Thus, activation of T cells by IL-15 renders T cells resistant to suppression by TGFβ1-producing tumor cells and rTGFβ1. This finding may be exploited in the design of new immunotherapy approaches that will rely on T cells avoiding tumor-induced suppression.
Plasmid DNAs Encoding Insulin and Glutamic Acid Decarboxylase 65 Have Distinct Effects on the Progression of Autoimmune Diabetes in Nonobese Diabetic Mice
Authors: Weaver Donald J. , Liu Bo , Tisch Roland 
Published: April 2014

AbstractWe previously demonstrated that administration of plasmid DNAs (pDNAs) encoding IL-4 and a fragment of glutamic acid decarboxylase 65 (GAD65) fused to IgGFc induces GAD65-specific Th2 cells and prevents insulin-dependent diabetes mellitus (IDDM) in nonobese diabetic (NOD) mice. To assess the general applicability of pDNA vaccination to mediate Ag-specific immune deviation, we examined the immunotherapeutic efficacy of recombinants encoding murine insulin A and B chains fused to IgGFc. Insulin was chosen based on studies demonstrating that administration of insulin or insulin B chain by a variety of strategies prevents IDDM in NOD mice. Surprisingly, young NOD mice receiving i.m. injections of pDNA encoding insulin B chain-IgGFc with or without IL-4 exhibited an accelerated progression of insulitis and developed early diabetes. Exacerbation of IDDM correlated with an increased frequency of IFN-γ-secreting CD4+ and CD8+ T cells in response to insulin B chain-specific peptides compared with untreated mice. In contrast, treatment with pDNAs encoding insulin A chain-IgGFc and IL-4 elicited a low frequency of IL-4-secreting Th cells and had no effect on the progression of IDDM. Vaccination with pDNAs encoding GAD65-IgGFc and IL-4, however, prevented IDDM. These results demonstrate that insulin- and GAD65-specific T cell reactivity induced by pDNA vaccination has distinct effects on the progression of IDDM.
Fas Aggregation Does Not Correlate with Fas-Mediated Apoptosis
Authors: Lee Yang-ja , Shacter Emily 
Published: April 2014

Abstract
Cross-linking of cell surface Fas molecules by Fas ligand or by agonistic anti-Fas Abs induces cell death by apoptosis. We found that a serine protease inhibitor, N-tosyl-l-lysine chloromethyl ketone (TLCK), dramatically enhances Fas-mediated apoptosis in the human T cell line Jurkat and in various B cell lines resistant to Fas-mediated apoptosis. The enhancing effect of TLCK is specific to Fas-induced cell death, with no effect seen on TNF-α or TNF-related apoptosis-inducing ligand-induced apoptosis. TLCK treatment had no effect on Fas expression levels on the cell surface, and neither promoted death-inducing signaling complex formation nor decreased expression levels of cellular inhibitors of apoptosis (FLICE inhibitory protein, X chromosome-linked inhibitor of apoptosis, and Bcl-2). Activation of the Fas-mediated apoptotic pathway by anti-Fas Ab is accompanied by aggregation of Fas molecules to form oligomers that are stable to boiling in SDS and β-ME. Fas aggregation is often considered to be required for Fas-mediated apoptosis. However, sensitization of cells to Fas-mediated apoptosis by TLCK or other agents (cycloheximide, protein kinase C inhibitors) causes less Fas aggregation during the apoptotic process compared with that in nonsensitized cells. These results show that Fas aggregation and Fas-mediated apoptosis are not directly correlated and may even be inversely correlated.
IL-1 Enhances T Cell-Dependent Antibody Production Through Induction of CD40 Ligand and OX40 on T Cells
Authors: Nakae Susumu , Asano Masahide , Horai Reiko , Sakaguchi Nobuo , Iwakura Yoichiro 
Published: April 2014

Abstract
IL-1 is a proinflammatory cytokine that plays pleiotropic roles in host defense mechanisms. We investigated the role of IL-1 in the humoral immune response using gene-targeted mice. Ab production against SRBC was significantly reduced in IL-1α/β-deficient (IL-1−/−) mice and enhanced in IL-1R antagonist−/− mice. The intrinsic functions of T, B, and APCs were normal in IL-1−/− mice. However, we showed that IL-1−/− APCs did not fully activate DO11.10 T cells, while IL-1R antagonist −/− APCs enhanced the reaction, indicating that IL-1 promotes T cell priming through T-APC interaction. The function of IL-1 was CD28-CD80/CD86 independent. We found that CD40 ligand and OX40 expression on T cells was affected by the mutation, and the reduced Ag-specific B cell response in IL-1−/− mice was recovered by the treatment with agonistic anti-CD40 mAb both in vitro and in vivo. These observations indicate that IL-1 enhances T cell-dependent Ab production by augmenting CD40 ligand and OX40 expression on T cells.
Cutting Edge: Leukocyte Receptor Complex-Encoded Immunomodulatory Receptors Show Differing Specificity for Alternative HLA-B27 Structures
Authors: Allen Rachel L. , Raine Tim , Haude Anja , Trowsdale John , Wilson Michael J. 
Published: April 2014

AbstractWe studied recognition of the disease-associated HLA-B27 allele by immunomodulatory receptors encoded within the leukocyte receptor complex. HLA class I are ligands for members of the killer Ig receptor (KIR) and Ig-like transcript (ILT)/LIR/LILR families (the new LILR nomenclature is described at www. gene.ucl.ac.uk/nomenclature/genefamily/lilr.html). Members of these families bound HLA-B27 in both classical and β2 microglobulin-independent forms. Classical complexes bound ILT2, ILT4, and LIR6 transfectants but not ILT1, ILT3, or ILT5. A free H chain form of HLA-B27 bound ILT4 and LIR6. Both forms of HLA-B27 bound KIR3DL1 transfectants. HLA-B27 free H chain bound CD14+ cells in PBL from healthy controls, consistent with ILT4 expression on monocytes. Alternative recognition of different forms of HLA-B27 by KIR or ILT could influence their immunomodulatory function and may imply a role in inflammatory disease.
Tumor-Infiltrating Macrophages Induce Apoptosis in Activated CD8+ T Cells by a Mechanism Requiring Cell Contact and Mediated by Both the Cell-Associated Form of TNF and Nitric Oxide
Authors: Saio Masanao , Radoja Sasa , Marino Mike , Frey Alan B. 
Published: April 2014

AbstractWe have investigated the ability of different cells present in murine tumors to induce apoptosis of activated CD8+ T cells in vitro. Tumor cells do not induce apoptosis of T cells; however, macrophages that infiltrate tumors are potent inducers of apoptosis. Tumor macrophages express cell surface-associated TNF, TNF type I (CD120a) and II (CD120b) receptors, and, upon contact with T cells which induces release of IFN-γ from T cells, secrete nitric oxide. Killing of T cells in vitro is blocked by Abs to IFN-γ, TNF, CD120a, or CD120b, or N-methyl-l-arginine. In concert with that finding, tumor macrophages isolated from either TNF type I or type II receptor −/− mice are not proapoptotic and do not produce nitric oxide upon contact with activated T cells. Control macrophages do not express TNF receptors or release nitric oxide. Tumor cells or tumor-derived macrophages do not express FasL, and blocking Abs to either Fas or FasL have no effect on macrophage-mediated T cell killing. These results demonstrate that macrophages which infiltrate tumors are highly proapoptotic and may be responsible for elimination of activated antitumor T cells within the tumor bed.
Role of CD28 for the Generation and Expansion of Antigen-Specific CD8+ T Lymphocytes During Infection withListeria monocytogenes
Authors: Mittrücker Hans-Willi , Kursar Mischo , Köhler Anne , Hurwitz Robert , Kaufmann Stefan H. E. 
Published: April 2014

AbstractInfection of mice with the intracellular bacterium Listeria monocytogenes results in a strong CD8+ T cell response that is critical for efficient control of infection. We used CD28-deficient mice to characterize the function of CD28 during Listeria infection, with a main emphasis on Listeria-specific CD8+ T cells. Frequencies and effector functions of these T cells were determined using MHC class I tetramers, single cell IFN-γ production and Listeria-specific cytotoxicity. During primary Listeria infection of CD28−/− mice we observed significantly reduced numbers of Listeria-specific CD8+ T cells and only marginal levels of specific IFN-γ production and cytotoxicity. Although frequencies were also reduced in CD28−/− mice during secondary response, we detected a considerable population of Listeria-specific CD8+ T cells in these mice. In parallel, IFN-γ production and cytotoxicity were observed, revealing that Listeria-specific CD8+ T cells in CD28−/− mice expressed normal effector functions. Consistent with their impaired CD8+ T cell activation, CD28−/− mice suffered from exacerbated listeriosis both after primary and secondary infection. These results demonstrate participation of CD28 signaling in the generation and expansion of Ag-specific CD8+ T cells in listeriosis. However, Ag-specific CD8+ T cells generated in the absence of CD28 differentiated into normal effector and memory T cells.
CD40 Ligand Promotes Priming of Fully Potent Antitumor CD4+ T Cells in Draining Lymph Nodes in the Presence of Apoptotic Tumor Cells
Authors: Fujita Nanae , Kagamu Hiroshi , Yoshizawa Hirohisa , Itoh Kazuhisa , Kuriyama Hideyuki , Matsumoto Naoya , Ishiguro Takuro , Tanaka Junta , Suzuki Eiichi , Hamada Hirofumi , Gejyo Fumitake 
Published: April 2014

AbstractThe presence or absence of CD4+ T cell help can determine the direction of adaptive immune responses toward either cross-priming or cross-tolerance. It has been demonstrated that interactions of CD40-CD40 ligand can replace CD4+ T cell help and enable dendritic cells to prime cytotoxic T cells. Here, we demonstrate that antitumor reactivity induced in regional lymph nodes (LNs) by s.c. injection of CD40 ligand (CD40L)-transduced tumor (MCA205 CD40L) showed far superior therapeutic efficacy against established brain tumors of a weakly immunogenic fibrosarcoma, MCA205, when adoptively transferred. Coinjection of apoptotic, but not necrotic parental tumor cells with CD40L-expressing tumor cells caused a strong synergistic induction of antitumor reactivity in tumor-draining LNs. Freshly isolated T cells from LNs immunized with apoptotic parental tumor cells and MCA205 CD40L were capable of mediating regression of the parental tumor in vivo. In contrast, T cells derived from LNs immunized without MCA205 CD40L required ex vivo anti-CD3/IL-2 activation to elicit therapeutic activity. On anti-CD3/IL-2 activation, cells from LNs immunized with MCA205 CD40L exhibited superior per cell antitumor reactivity. An in vitro depletion study revealed that either CD4+ or CD8+ T cells could mediate therapeutic efficacy but that the antitumor efficacy mediated by CD4+ T cells was far superior. Cytosolic flow cytometric analyses indicated that priming of CD4+ cells in LNs draining CD40L-expressing tumors was polarized to the Th1 type. This is the first report that fully potent antitumor CD4+ T cell priming was promoted by s.c. injection of CD40L-transduced tumor in the presence of apoptotic tumor cells.