Transferrin cleavage during acute inflammation in the goldfish, Carassius auratus

• Author / Creator

  Trites, Michael

• Transferrin is an evolutionary conserved protein that in addition to having a critical role in iron transport also has been shown to have a crucial role in host defence. Transferrin has been shown to sequester iron from invading pathogens, act directly against microbial pathogens, and is an evolutionary conserved acute phase protein. Recently, cleaved transferrin products have been shown to activate both teleost and murine macrophages in vitro. The objectives of my thesis were to characterize the presence and regulation of cleaved transferrin products to acute inflammation. I used an in vivo model of self-resolving inflammation in goldfish, coupled with analysis of leucocyte anti-microbial analysis responses. Specifically: gene expression, leucocyte influx, respiratory burst, and nitric oxide production. I also used protein analysis to evaluate the contributions of cleaved transferrin to acute inflammation. I show, for the first time that cleaved transferrin products are produced in vivo during an acute inflammatory response. I initially investigated the ability of cleaved transferrin fragments to serve as a broader marker of the acute inflammatory response compared to short-lived and low concentration cytokines. Cleaved transferrin fragments were produced during pathogen induced, but not sterile, inflammation. However there was a large degree of heterogeneity in banding patterns within transferrin cleavage products detected by Western blot, and there are likely a multitude of cleavage products generated in vivo that were undetected with the primary antibody used. I then investigated the potential contributions of transferrin cleavage products during acute inflammation in vivo. Macrophages, but not neutrophils, potentially contribute to production of transferrin through inducible expression of transferrin during inflammation. Pro-inflammatory neutrophils, in contrast, displayed a preferential ability to enzymatically digest transferrin; that was reduced in macrophages and late-phase pro-resolving neutrophils. This study adds to a growing body or work highlighting the role of transferrin as an immune regulator during acute inflammation. Given the significant conservation of this and related molecules, these findings have potentially broad implications for host defences and inflammation control across evolution. Overall the data presented suggests that cleaved transferrin products may play a role during activation events of macrophages in vivo and this mechanism is likely conserved throughout evolution.

• Subjects / Keywords

  • Transferrin
  • Acute inflammation
  • Evolution
  • Teleost immunity

• Graduation date

  Fall 2016

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R32N4ZV0B

• 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.