The analysis of cytokine regulation of macrophage antimicrobial responses of the goldfish (Carassius auratus L.)

  • Author / Creator
    Grayfer, Leon
  • Inflammation is a highly regulated immune response to tissue damage, infiltrating pathogens or both. Cells of the myeloid lineage such as macrophages are indispensable for the initiation, progression and resolution of inflammation. Macrophages possess an armamentarium of antimicrobial responses that are under cytokine regulation. The key inflammatory cytokines have been extensively characterized in mammals and their homologues have been identified across bony fish (teleosts). However, the specific functional roles of these teleost inflammatory cytokines have not been extensively studied. My doctoral research focused on characterizing the roles of key goldfish (Carassius auratus L.) inflammatory cytokines in the regulation of macrophage antimicrobial processes and in host defense against the fish pathogen, Mycobacterium marinum. I examined at the molecular and functional levels major goldfish pro-inflammatory cytokines TNFα, IFNγ, IFNγrel, their cognate receptors as well as the anti-inflammatory cytokine, IL-10. I also assessed the inflammatory mechanisms governing the antithesis of antimicrobial defenses and pathogen evasion during M. marinum infections of goldfish monocytes and macrophages. Unlike mammals, goldfish possess two Type II interferons, IFNγ and IFNγ related protein (IFNγrel). I established that zebrafish and goldfish also possess two interferon gamma receptor 1 chains (IFNGR1-1 and IFNGR1-2), where the goldfish rgIFNγ strictly bound rgIFNGR1-2 while rgIFNγrel exclusively engaged rgIFNGR1-1. Furthermore, rgIFNγ and rgIFNγrel elicited distinct antimicrobial responses and immune gene expression patterns in goldfish monocytes and macrophages. While the recombinant goldfish tumor necrosis factor alpha (rgTNFα) exhibited pro-inflammatory roles attributed to its mammalian counterpart, goldfish TNFα ligands (rgTNFα1 and rgTNFα2) and receptors (rgTNF-R1 and rgTNF-R2) formed dimers and not trimers, as in mammals. In the first functional analysis of a teleost interleukin-10, I demonstrated that rgIL-10 conferred anti-inflammatory properties towards goldfish monocytes. M. marinum infections of goldfish monocytes and macrophages ablated their cytokine-induced antimicrobial responses through several mechanisms. Intermittently, infected monocytes and macrophages increased their expression of pro-inflammatory genes while cells activated with rgTNFα2, rgIFNγ, or rgIFNγrel exhibit decreased viability of infecting M. marinum. Together, these findings provide an in vitro model system for investigating cytokine regulation of monocyte/macrophage antimicrobial responses and mycobacterium-host cell immune interactions of a lower vertebrate species.

  • Subjects / Keywords
  • Graduation date
  • Type of Item
  • Degree
    Doctor of Philosophy
  • DOI
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.
  • Language
  • Institution
    University of Alberta
  • Degree level
  • Department
    • Department of Biological Sciences
  • Supervisor / co-supervisor and their department(s)
    • Dr. Miodrag Belosevic (Department of Biological Sciences)
  • Examining committee members and their departments
    • Dr. Declan Ali (Department of Biological Sciences)
    • Dr. Catherine J. Field (Department of Agricultural, Food & Nutritional Science)
    • Dr. Brian Dixon (Department of Biology, University of Waterloo)
    • Dr. Greg G. Goss (Department of Biological Sciences)