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 CBER Research Projects

Project Title

Molecular Mechanisms of the Activation of Myeloid Antigen Presenting Cells

Principal Investigator

David Frucht

Laboratory

Laboratory of Cell Biology; Division of Monoclonal Antibodies; Office of Therapeutics Research and Review

Project Summary

My lab, along with other laboratories, has shown that myeloid antigen presenting cells (APC) have many functions previously assigned only to T helper-1 (Th1) cells. For example, macrophages and dendritic cells make interferon gamma (IFN-g) in certain settings soon following immune activation, allowing sentinel immune defenses to occur in the absence of specific recognition by T cells. We have also demonstrated that activated APC express the transcription factors, STAT4 and T-bet, initially described as lymphoid factors that promote IFN-g production. STAT4 is required for IL-12-dependent IFN-g production by APC, and T-bet mRNA levels correspond well with the levels of APC-expressed IFN-g mRNA. Each of these factors is not expressed in resting cells, but induced to high levels following various types of activating signals, including IFN-g. In this manner, both STAT4 and T-bet are central to positive feedback loops in which their expression levels are upregulated by a cytokine that they in turn induce.

The primary goal of this laboratory is to investigate other roles of these two key transcription factors in the function of antigen presenting cells using a multi-pronged approach as follows:

  1. Experiments with gene targeted mice: Various APC populations are being isolated from wild type, Stat4 -/-, and Stat6 -/- mice (deficient in IL-4 signaling) and evaluated for their costimulatory function (ability to induce T cell proliferation, IFN-g production, IL-4 production). Methods of adoptive transfer of APC are being developed to determine whether differences observed in vitro result in functional consequences in vivo, including responses to intracellular infection.

  2. Overexpression models: Methods are being developed to overexpress Stat4 and T-bet in APC using transfection and retroviral transduction. Differences in costimulatory function will be evaluated as described in approach #1. Moreover, T-bet and Stat4 transgenic mice are being generated with a construct driven by an MHCII promoter, in which APC will overexpress these molecules. These animal models will allow evaluation of costimulatory function ex vivo and in vivo.

Another goal of the laboratory is to re-evaluate the functional significance of APC production of interferon gamma. We hypothesize that it may play a role in sentinel defenses. This question will be addressed through adoptive transfer of wild type APC into IFNg -/- recipients and the use of various infection models. Moreover, we are actively collaborating with two laboratories with overlapping interests IL-12 signal transduction.

Publications

  • Trends Immunol 2001 Oct;22(10):556-60
    IFN-gamma production by antigen-presenting cells: mechanisms emerge.
    Frucht DM, Fukao T, Bogdan C, Schindler H, O'Shea JJ, Koyasu S
    Pub Med

  • Clin Immunol 2001 Sep;100(3):270-6
    Detection of intracellular phosphorylated STAT-4 by flow cytometry.
    Uzel G, Frucht DM, Fleisher TA, Holland SM
    Pub Med

  • J Immunol 2001 Apr 1;166(7):4446-55
    Inducible expression of Stat4 in dendritic cells and macrophages and its critical role in innate and adaptive immune responses.
    Fukao T, Frucht DM, Yap G, Gadina M, O'Shea JJ, Koyasu S
    Pub Med

  • Blood 2001 Aug 1;98(3):851-9
    The familial Mediterranean fever protein, pyrin, associates with microtubules and colocalizes with actin filaments.
    Mansfield E, Chae JJ, Komarow HD, Brotz TM, Frucht DM, Aksentijevich I, Kastner DL
    Pub Med

  • J Immunol 2000 May 1;164(9):4659-64
    Stat4 is expressed in activated peripheral blood monocytes, dendritic cells, and macrophages at sites of Th1-mediated inflammation.
    Frucht DM, Aringer M, Galon J, Danning C, Brown M, Fan S, Centola M, Wu CY, Yamada N, El Gabalawy H, O'Shea JJ
    Pub Med

  • Blood 2000 May 15;95(10):3223-31
    The gene for familial Mediterranean fever, MEFV, is expressed in early leukocyte development and is regulated in response to inflammatory mediators.
    Centola M, Wood G, Frucht DM, Galon J, Aringer M, Farrell C, Kingma DW, Horwitz ME, Mansfield E, Holland SM, O'Shea JJ, Rosenberg HF, Malech HL, Kastner DL
    Pub Med

  • Mol Cell Biol 2000 Jun;20(12):4371-80
    Hierarchy of protein tyrosine kinases in interleukin-2 (IL-2) signaling: activation of syk depends on Jak3; however, neither Syk nor Lck is required for IL-2-mediated STAT activation.
    Zhou YJ, Magnuson KS, Cheng TP, Gadina M, Frucht DM, Galon J, Candotti F, Geahlen RL, Changelian PS, O'Shea JJ
    Pub Med

  • J Immunol 2000 Feb 15;164(4):1768-74
    Inhibition of Th1 immune response by glucocorticoids: dexamethasone selectively inhibits IL-12-induced Stat4 phosphorylation in T lymphocytes.
    Franchimont D, Galon J, Gadina M, Visconti R, Zhou Y, Aringer M, Frucht DM, Chrousos GP, O'Shea JJ
    Pub Med

Last Updated: 4/1/2002

 

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Date created: September 24, 2003
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