|Ph.D Student||Koren-Gluzer Marie|
|Subject||Exploring the Differential Role of CXCR3 Ligands in the|
Regulation of Immunity Using a Mutated Soluble
|Department||Department of Medicine||Supervisor||Professor Nathan Karin|
|Full Thesis text - in Hebrew|
Experimental allergic encephalomyelitis (EAE) is an experimental autoimmune disease of the central nervous system (CNS), serving as a model for Multiple Sclerosis (MS).
The development and progression of EAE is driven by antigen specific effectors T cells (i.e. Th1 and Th17).
CXCR3 is a chemokine receptor preferentially expressed on inflammatory effectors T cells including Th1, as well as IL-17 producing Th17 cells.
Three ligands compete on binding this receptor: CXCL9 (MIG), CXCL10 (IP-10) and CXCL11 (I-TAC). These ligands bind different epitopes on CXCR3, yet CXCL11 may antagonize the function of the other CXCR3 ligands, since it rapidly leads to receptor internalization, which thus becomes inaccessible to the other CXCR3 ligands.
As CXCR3 is predominantly expressed on CD4+ effectors Th1 and Th17 cells, and since it is likely to be associated with the migration of these cells to the site of inflammation, it is conceivable that mice lacking CXCR3 would be less susceptible to T cell mediated inflammatory autoimmunity.
Paradoxically, CXCR3-/- mice develop an extremely severe form of experimental allergic encephalomyelitis (EAE).
The current study explicates this paradox showing that whereas CXCL9 and CXCL10 are pro-inflammatory chemokines, CXCL11 functions as an anti inflammatory, regulatory chemokine.
We have confirmed this hypothesis, by generating a soluble receptor (CXCR3 (MUT) ) that selectively neutralizes CXCL9 and CXCL10 but not CXCL11.
We have cloned CXCR3 E3 domain and generated a mutated variant with a single point mutation of the first Aspartic acid to Alanine. The recombinant soluble chimera fused to the constant region (Hinge-CH2-CH3) of mouse and human IgG1 Fc, and produced it in the CHO- dhfr-/- mammalian expression system.
Our results show that CXCR3 (MUT) selectively binds CXCL9 and CXCL10 and neutralizes their biological functions. Furthermore, CXCL11 was found to change the cytokine profile of primary spleen cell from EAE mice from high IFN-γ, high IL-17 to high IL-10 high IL-4 profile.
Moreover, CXCR3(MUT) could effectively suppress the in vivo biological activity of CXCL9 and CXCL10, attenuating ongoing experimental autoimmune encephalomyelitis (EAE).
This therapeutic ability caused by repolarization of antigen specific T cells from inflammatory into regulatory cells.