Poster Presentation The 43rd Lorne Conference on Protein Structure and Function 2018

Defining the biochemical and intrinsic biological properties of the novel interferon, IFNε. (#168)

Nicole A De Weerd 1 2 , Sebastian A Stifter 1 3 , Antony Y Matthews 1 2 , Niamh E Mangan 1 2 , KaYee Fung 1 4 , Alexander Drew 1 , Michelle D Tate 1 2 , Tatiana P Soares da Costa 5 , Daniel Hampsey 6 , Jemma Mayall 6 , Phil M Hansbro 6 , Albert Garcia-Minambres 7 , Sahar G Eid 8 , Johnson Mak 8 9 , Judy Scoble 10 , George Lovrecz 10 , Paul J Hertzog 1 2
  1. Hudson Institute of Medical Research, Clayton, VIC, Australia
  2. Department of Molecular and Translational Sciences, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Victoria, Australia
  3. The Centenary Institute, Camperdown, NSW, Australia
  4. Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
  5. LaTrobe Institute for Molecular Sciences, Bundoora, VIC, Australia
  6. Hunter Medical Research Institute, Newcastle, NSW
  7. Deakin University, Geelong, VIC, Australia
  8. Deakin University, Geelong, VIC, Australia
  9. CSIRO Australian Animal Health Laboratory, Geelong, VIC, Australia
  10. CSIRO Manufacturing, Parkville, VIC, Australia

The type I interferons (IFNs) are a family of cytokines with diverse biological activities including antiviral, antiproliferative, and immunoregulatory functions. The discovery of the hormonally-regulated IFNε, which is constitutively expressed in the female reproductive tract, suggested a role for IFNs in both homeostasis and protection from infection at this unique site; however the intrinsic properties of IFNε were yet to be determined. We generated a recombinant form of murine (m)IFNε and report here its functional characterization. Recombinant mIFNε exhibited an α-helical fold, characteristic of other type I IFNs, and showed affinity for the extracellular domains (ECD) of murine IFN alpha/beta receptor (IFNAR)1-ECD and IFNAR2-ECD, albeit with an uncharacteristic preference for IFNAR1-ECD. Nevertheless, mIFNε induced typical type I IFN signaling activity, including STAT1 phosphorylation and activation of canonical type I IFN signaling reporters, demonstrating that it utilizes the canonical JAK/STAT signaling pathway. We also found that, similar to other type I IFNs, mIFNε exhibited antiviral, antiproliferative, and antibacterial activities, albeit with 100- to 1000-fold reduced potency compared with mIFNα1 and mIFNβ. mIFNε was also demonstrated to upregulate a lymphocyte activation marker (CD69) on T, B, and NK cells, again at reduced efficacy compared to mIFNα1 and mIFNβ. Surprisingly, although type I IFNs generally do not display cross-species activities, mIFNε exhibited an affinity for human IFNAR1-ECD and IFNAR2-ECD, and high antiviral activity on human cells, suppressing HIV replication and inducing the expression of known HIV-restriction factors in primary human lymphocytes. Our findings define the intrinsic properties of mIFNε, indicating that it distinctly interacts with IFNAR and elicits pathogen-suppressing activity with a potency enabling host defence, but with limited toxicity, appropriate for a protein expressed constitutively in a sensitive mucosal site, such as the reproductive tract.