1140. Use of Fungal-like Particles to Probe Dectin-1 Responses in Innate Immunity
Session: Poster Abstract Session: Innate and Adaptive Immunity to Infections
Saturday, October 22, 2011
Room: Poster Hall B1
Handouts
  • IDSA poster_Mansour_2011_v3.pdf (5.7 MB)
  • Background: Due to the increased use of immunosuppressive treatments for transplant recipients, the number of life-threatening fungal infections has risen.  Identification of the rules that govern an appropriate immune response to these invasive fungal pathogens is essential to develop better diagnostics, and targeted therapeutics.  The precise events at the initial pathogen-innate immune interface will determine the appropriate adaptive response.  Pattern recognition receptors recognize a diverse number of epitopes but recently have been described to bind carbohydrate antigens.  β-glucan (BG) is an immunodominant repeating glucose cell wall component of many fungal pathogens recognized by Dectin-1.  An obstacle to studying BG recognition is the confounding presence of multiple types of carbohydrates on fungal cell walls.  In order to characterize the response to each of these purified carbohydrate antigens, we describe a novel system for the construction of fungal-like particles. 

    Methods: The three-dimensional shape of a fungal pathogen was mimicked using a polystyrene bead platform. Purified BG was conjugated to the surface of beads and examined using flow cytometry and transmission-electron microscopy. BG-beads were exposed to detergents as well as gluconases to test conjugation stability. Finally, BG-beads were incubated with GFP-Dectin-1 expressing macrophages and imaged using confocal microscopy.

    Results: Electron microscopy revealed a layer of BG co-localized onto the surface of polystyrene beads.  Despite increasing detergent stringency, BG was shown to remain bound to the surface of beads suggesting covalent conjugation.  The ability to detect BG by anti-BG antibody was abrogated by pre-treating BG-beads with laminarinase, a β-1,3-gluconase, but not proteinase K.  Uptake of BG-beads occurred within minutes by macrophages and GFP-Dectin-1 recruitment to the phagosome was retained as compared to uncoated beads.

    Conclusion: Understanding the early immune response to fungal carbohydrate antigens is crucial to the development of future therapeutics.  This data describes a novel fungal-like particle system that allows immunologists to dissect the critical steps in recognition of fungal carbohydrate antigens by innate immune cells.


    Subject Category: E. Innate and adaptive immunity to infections, including vaccine immunology

    Michael Mansour, M.D., Ph.D.1, Jenny Tam, Ph.D.1, Nicholas Yoder, Ph.D.2, Nida Khan, B.S.1 and Jatin M. Vyas, M.D., Ph.D.3, (1)Massachsetts General Hospital, Division of Infectious Diseases, Boston, MA, (2)Whitehead Institute for Biomedical Research, Cambridge, MA, (3)Massachusetts General Hospital, Division of Infectious Disease, Boston, MA

    Disclosures:

    M. Mansour, None

    J. Tam, None

    N. Yoder, None

    N. Khan, None

    J. M. Vyas, None

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