The Experts below are selected from a list of 306 Experts worldwide ranked by ideXlab platform
Nobuko Yoshida - One of the best experts on this subject based on the ideXlab platform.
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beta adrenergic antagonist propranolol inhibits mammalian cell lysosome spreading and invasion by trypanosoma cruzi metacyclic forms
Microbes and Infection, 2017Co-Authors: Silene Macedo, Joao Paulo Ferreira Rodrigues, Sergio Schenkman, Nobuko YoshidaAbstract:The involvement of β-adrenergic receptor (β-AR) in host cell invasion by Trypanosoma cruzi metacyclic trypomastigote (MT) is not known. We examined whether isoproterenol, an agonist of β-AR, or nonselective β-blocker propranolol affected MT internalization mediated the stage-specific Surface Molecule gp82. Treatment of HeLa cells with propranolol significantly inhibited MT invasion whereas isoproterenol had no effect. Propranolol, but not isoproterenol, also inhibited the lysosome spreading required for gp82-dependent MT invasion. The effect of propranolol in inhibiting MT internalization was not due to the prevention of gp82 interaction with β-AR. It was mainly associated with its ability to impair lysosome spreading.
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starvation and rapamycin differentially regulate host cell lysosome exocytosis and invasion by trypanosoma cruzi metacyclic forms
Cellular Microbiology, 2011Co-Authors: Rafael M Martins, Renan Melatto Alves, Silene Macedo, Nobuko YoshidaAbstract:Summary The molecular mechanisms of host cell invasion by T. cruzi metacyclic trypomastigotes (MT), the developmental forms that initiate infection in the mammalian host, are only partially understood. Here we aimed at further identifying the target cell components involved in signalling cascades leading to MT internalization, and demonstrate for the first time the participation of mammalian target of rapamycin (mTOR). Treatment of human epithelial HeLa cells with mTOR inhibitor rapamycin reduced lysosomal exocytosis and MT invasion. Downregulation of phosphatidylinositol 3-kinase and protein kinase C also impaired exocytosis and MT internalization. The recombinant protein based on gp82, the MT Surface Molecule that mediates cell adhesion/invasion, induced exocytosis in HeLa cells. Such an effect has not previously been attributed to any T. cruzi Surface Molecule. Rapamycin treatment diminished gp82 binding as well. Cell invasion assays under conditions that promoted lysosome exocytosis, such as 1 h incubation in starvation medium PBS++, increased MT invasion, whereas pre-starvation of cells for 1–2 h had an opposite effect. In contrast to MT, invasion of tissue culture trypomastigotes (TCT) increased upon host cell pre-starvation or treatment with rapamycin, a novel finding that discloses quite distinctive features of the two infective forms in a key process for infection.
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Cell adhesion and Ca2+ signaling activity in stably transfected Trypanosoma cruzi epimastigotes expressing the metacyclic stage-specific Surface Molecule gp82.
Infection and immunity, 2003Co-Authors: Patricio M. Manque, Ivan Neira, Vanessa D. Atayde, José Franco Da Silveira, Esteban M. Cordero, Alice T. Ferreira, Marcel I. Ramirez, Nobuko YoshidaAbstract:Metacyclic trypomastigotes of Trypanosoma cruzi express a developmentally regulated 82-kDa Surface glycoprotein (gp82) that has been implicated in host cell invasion. gp82-mediated interaction of metacyclic forms with target cells induces in both cells activation of the signal transduction pathways, leading to intracellular Ca(2+) mobilization, which is required for parasite internalization. Noninfective epimastigotes do not express detectable levels of gp82 and are unable to induce a Ca(2+) response. We stably transfected epimastigotes with a T. cruzi expression vector carrying the metacyclic stage gp82 cDNA. These transfectants produced a functional gp82, which bound to and triggered a Ca(2+) response in HeLa cells, in the same manner as the metacyclic trypomastigote gp82. Such properties were not found in epimastigotes transfected with the plasmid vector alone. Epimastigotes expressing gp82 on the Surface adhered to HeLa cells but were not internalized. Treatment of gp82-expressing epimastigotes with forskolin, an activator of adenylyl cyclase that increases the metacyclic trypomastigote entry into target cells, did not promote parasite internalization. P175, an intracellular tyrosine phosphorylated protein, which appears to play a role in gp82-dependent signaling cascade in metacyclic forms, was undetectable in epimastigotes, either transfected or not with pTEX-gp82. Overall, our results indicate that gp82 is required but not sufficient for target cell invasion.
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identification of a domain of trypanosoma cruzi metacyclic trypomastigote Surface Molecule gp82 required for attachment and invasion of mammalian cells
Molecular and Biochemical Parasitology, 1996Co-Authors: Fabio R Santori, José Franco Da Silveira, Miriam L Dorta, Luiz Juliano, Maria A Juliano, Rita C Ruiz, Nobuko YoshidaAbstract:Recombinant proteins and synthetic peptides representing various sequences of gp82, a Surface glycoprotein of Trypanosoma cruzi metacyclic trypomastigotes implicated in mammalian cell invasion, were used in this study aiming at the identification of the domain(s) of this Molecule required for interaction with target cells. Invasion of cultured HeLa cells by metacyclic trypomastigotes was inhibited by about 80% in the presence of native gp82 or the corresponding recombinant construct J18. Inhibition by recombinant proteins J18a and J18b, containing respectively the N-terminal and the C-terminal portions of gp82, was on the order of 30% and 65%. As compared to J18b (amino acids 224–516), the truncated gp82 fragments J18b1 (amino acids 303–516) and J18b2 (amino acids 357–516) displayed lower inhibitory effect (∼40% and ∼15%, respectively). Compatible with these observations, we found that the recombinant protein J18b, but not J18a or J18b2, binds to HeLa cells in a dose-dependent and saturable fashion. Experiments with ten overlapping synthetic peptides, representing the gp82 portion spanning amino acids 224–333, showed that peptides 4 (amino acids 254–273) and 8 (amino acids 294–313) have significant inhibitory activity on HeLa cell invasion by metacyclic forms. All these results indicate that the portion of gp82 required for mammalian cell attachment and invasion is located in the central domain of the Molecule.
Jeffrey K Actor - One of the best experts on this subject based on the ideXlab platform.
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post spaceflight sts 135 mouse splenocytes demonstrate altered activation properties and Surface Molecule expression
PLOS ONE, 2015Co-Authors: Shenan Hwang, Brian E Crucian, Clarence Sams, Jeffrey K ActorAbstract:Alterations in immune function have been documented during or post-spaceflight and in ground based models of microgravity. Identification of immune parameters that are dysregulated during spaceflight is an important step in mitigating crew health risks during deep space missions. The in vitro analysis of leukocyte activity post-spaceflight in both human and animal species is primarily focused on lymphocytic function. This report completes a broader spectrum analysis of mouse lymphocyte and monocyte changes post 13 days orbital flight (mission STS-135). Analysis includes an examination in Surface markers for cell activation, and antigen presentation and co-stimulatory Molecules. Cytokine production was measured after stimulation with T-cell mitogen or TLR-2, TLR-4, or TLR-5 agonists. Splenocyte Surface marker analysis immediate post-spaceflight and after in vitro culture demonstrated unique changes in phenotypic populations between the flight mice and matched treatment ground controls. Post-spaceflight splenocytes (flight splenocytes) had lower expression intensity of CD4+CD25+ and CD8+CD25+ cells, lower percentage of CD11c+MHC II+ cells, and higher percentage of CD11c+MHC I+ populations compared to ground controls. The flight splenocytes demonstrated an increase in phagocytic activity. Stimulation with ConA led to decrease in CD4+ population but increased CD4+CD25+ cells compared to ground controls. Culturing with TLR agonists led to a decrease in CD11c+ population in splenocytes isolated from flight mice compared to ground controls. Consequently, flight splenocytes with or without TLR-agonist stimulation showed a decrease in CD11c+MHC I+, CD11c+MHC II+, and CD11c+CD86+ cells compared to ground controls. Production of IFN-γ was decreased and IL-2 was increased from ConA stimulated flight splenocytes. This study demonstrated that expression of Surface Molecules can be affected by conditions of spaceflight and impaired responsiveness persists under culture conditions in vitro.
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dysregulated response to mycobacterial cord factor trehalose 6 6 dimycolate in cd1d mice
Journal of Interferon and Cytokine Research, 2001Co-Authors: Jeffrey K Actor, Margaret Olsen, Robert L Hunter, Yongjian GengAbstract:The biologic effects of the mycobacterial glycolipid trehalose-6,6′-dimycolate (TDM) include granuloma formation and macrophage activation and are dependent on physical conformation. In mice, the group II CD1 Surface Molecule CD1d has been implicated in glycolipid presentation. The importance of CD1d interactions in pathology has yet to be established. We hypothesized that mice lacking CD1d (CD1D-/-) would demonstrate dysregulated granulomatous response to TDM, compared with CD1D+/- heterozygous controls. Mice were intravenously injected with TDM-coated polystyrene-divinylbenzene beads and examined for histologic response and for changes in inflammatory cytokine and chemokine mRNA. Control CD1D heterozygous mice demonstrated a granulomatous response, which peaked at day 5. Increased mRNA for tumor necrosis factor-α (TNF-α) and macrophage inflammatory protein-1α (MIP-1α) correlated with development of granulomas, with very little change in interleukin-1β (IL-1β) and monocyte chemoattractant protein-1 (MCP-...
Ikuya Yano - One of the best experts on this subject based on the ideXlab platform.
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in vivo administration of mycobacterial cord factor trehalose 6 6 dimycolate can induce lung and liver granulomas and thymic atrophy in rabbits
Infection and Immunity, 2000Co-Authors: Naoko Hamasaki, Koichi Isowa, Kohachi Kamada, Yoshitake Terano, Takayuki Matsumoto, Tetsuo Arakawa, Kazuo Kobayashi, Ikuya YanoAbstract:Trehalose 6,6′-dimycolate (TDM) is a cell Surface Molecule of Mycobacterium tuberculosis. TDM induced a loss of body weight and prominent granulomas in the liver and lungs by the intravenous injection of TDM into rabbits. TDM also induced atrophy of the thymus and spleen due to apoptosis. By contrast, sulfolipid (2,3,6,6′-tetraacyl trehalose 2′-sulfate) induced neither toxicity, nor granuloma formation, nor atrophy of the thymus and spleen. In rabbits the histopathological changes were more dramatic than in mice. The rabbit model may be more sensitive and may provide more information on the beneficial or pathological effects of TDM.
John R Yannelli - One of the best experts on this subject based on the ideXlab platform.
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autologous dendritic cell vaccines for non small cell lung cancer
Journal of Clinical Oncology, 2004Co-Authors: Edward A Hirschowitz, Terry Foody, Richard J Kryscio, Larry Dickson, Jamie Sturgill, John R YannelliAbstract:Purpose Therapeutic outcomes of definitively treated non–small-cell lung cancer (NSCLC) are unacceptably poor. A wealth of preclinical information, and a modest amount of clinical information indicate that dendritic cell (DC) vaccines have therapeutic potential. Only a handful of NSCLC patients have been included in DC clinical trials. We delivered autologous DC vaccines to 16 individuals with stage IA to IIIB NSCLC treated with surgery, chemoradiation, or multimodality therapy. The objectives of the study were to evaluate tolerability and measure immunologic responses to DC vaccines in a heterogeneous group of NSCLC patients. Methods DC vaccines were generated from CD14+ precursors, pulsed with apoptotic bodies of an allogeneic NSCLC cell line that overexpressed Her2/neu, CEA, WT1, Mage2, and survivin. DCs were partially matured with a factor that induced Surface Molecule expression but minimal cytokine production. Individuals were immunized intradermally two times, 1 month apart. Peripheral blood was dr...
Alessandro Moretta - One of the best experts on this subject based on the ideXlab platform.
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nkp44 a novel triggering Surface Molecule specifically expressed by activated natural killer cells is involved in non major histocompatibility complex restricted tumor cell lysis
Journal of Experimental Medicine, 1998Co-Authors: Massimo Vitale, Simona Sivori, Lorenza Sanseverino, Raffaella Augugliaro, Cristina Bottino, Lorenzo Moretta, Roberta Castriconi, Emanuela Marcenaro, Alessandro MorettaAbstract:After culture in interleukin (IL)-2, natural killer (NK) cells acquire an increased capability of mediating non–major histocompatibility complex (MHC)–restricted tumor cell lysis. This may reflect, at least in part, the de novo expression by NK cells of triggering receptors involved in cytolysis. In this study we identified a novel 44-kD Surface Molecule (NKp44) that is absent in freshly isolated peripheral blood lymphocytes but is progressively expressed by all NK cells in vitro after culture in IL-2. Different from other markers of cell activation such as CD69 or VLA.2, NKp44 is absent in activated T lymphocytes or T cell clones. Since NKp44 was not detected in any of the other cell lineages analyzed, it appears as the first marker specific for activated human NK cells. Monoclonal antibody (mAb)–mediated cross-linking of NKp44 in cloned NK cells resulted in strong activation of target cell lysis in a redirected killing assay. This data indicated that NKp44 can mediate triggering of NK cell cytotoxicity. mAb-mediated masking of NKp44 resulted in partial inhibition of cytolytic activity against certain (FcγR-negative) NK-susceptible target cells. This inhibition was greatly increased by the simultaneous masking of p46, another recently identified NK-specific triggering Surface Molecule. These data strongly suggest that NKp44 functions as a triggering receptor selectively expressed by activated NK cells that, together with p46, may be involved in the process of non-MHC-restricted lysis. Finally, we show that p46 and NKp44 are coupled to the intracytoplasmic transduction machinery via the association with CD3ζ or KARAP/DAP12, respectively; these associated Molecules are tyrosine phosphorylated upon NK cell stimulation.
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p46 a novel natural killer cell specific Surface Molecule that mediates cell activation
Journal of Experimental Medicine, 1997Co-Authors: Simona Sivori, Massimo Vitale, Luigia Morelli, Lorenza Sanseverino, Raffaella Augugliaro, Cristina Bottino, Lorenzo Moretta, Alessandro MorettaAbstract:Limited information is available on the Surface Molecules that are involved in natural killer (NK) cell triggering. In this study, we selected the BAB281 monoclonal antibody (mAb) on the basis of its ability to trigger NK-mediated target cell lysis. BAB281 identified a novel NK cell–specific Surface Molecule of 46 kD (p46) that is expressed by all resting or activated NK cells. Importantly, unlike the NK cell antigens identified so far, the expression of p46 was strictly confined to NK cells. Upon mAb-mediated cross-linking, p46 Molecules induced strong cell triggering leading to [Ca2+]i increases, lymphokine production, and cytolytic activity both in resting NK cells and NK cell clones. The p46-mediated induction of Ca2+ increases or triggering of cytolytic activity was downregulated by the simultaneous engagement of inhibitory receptors including p58, p70, and CD94/NKG2A. Both the unique cellular distribution and functional capability of p46 Molecules suggest a possible role in the mechanisms of non-major histocompatibility complex–restricted cytolysis mediated by human NK cells.