טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentVitenshtein Alon
SubjectCharacterization of a Novel Type I Decoy Receptor with a
Regulatory Function in Autoimmunity
DepartmentDepartment of Medicine
Supervisor Professor Nathan Karin
Full Thesis textFull thesis text - English Version


Abstract

Studying a previously cloned splice variant of the murine IL-27RA we have accumulated convincing evidence that this variant in fact encodes a decoy receptor for IL-23 and IL-27 and plays a regulatory function in autoimmunity. Thus we named this isoform Type 1 Decoy receptor, T1DR. Initially we identified selective binding of the splice variant encoding recombinant protein to IL-23 and IL-27. We also demonstrate that this isoform retained the capacity to neutralize these ligands in cytokine specific designed biological assays. Although IL-27 has Th1 polarizing as well as Th17 suppressing pleiotropic properties IL-23 is an inflammatory cytokine key in the polarization and maintenance of the highly pathogenic Th17 cell phenotype implicated as drivers of autoimmunity. Therefore, we sought to study the dynamics of these two cytokines in EAE, a murine autoimmune model of Multiple Sclerosis, as well as examine the therapeutic potential of this splice variant in this model. Administration of our recombinant protein in vitro to auto-reactive culture from EAE induced mice in their pre-symptomatic phase of disease, mainly demonstrated a concomitant decrease in Th1 and Th17 cells. These findings encouraged us to proceed to treatment of mice in vivo during the symptomatic phase of ongoing EAE. Treated mice exhibited a significant recovery as well as a pronounced reduction in CNS Th17 frequencies and total mononuclear cell infiltration. We also generated a T1DR specific DNA vaccination based polyclonal antibody. This antibody enabled us initiate the characterization of the endogenous T1DR and to learn whether it participates in regulation of the inflammatory process in EAE. We observed that administration of this antibody to mice with ongoing EAE produced the opposite effect to T1DR administration. Disease symptoms were aggravated. This exacerbation included increased relative number of Th17 and mononuclear infiltrates within the CNS. Also presented are initial findings of T1DR activity in human culture for relevance to human biology. Finally, applying our gained insight, we present two candidate splice variants, potentially encoding decoy receptors, which are also formed by the unique retention of an intron.