Modulation of IRBP Peptide-Specific T Cell by Gene Transfer

Abstract

Abstract: : Purpose: Autoimmune uveitis (AU) is an inflammatory disorder mediated by autoreactive CD4⁺ T cells. Interphotoreceptor binding protein (IRBP) is one of the candidate autoantigens responsible for AU. IRBP peptide 1-20 (IRBP_1-20) has been identified as a major uveitogenic epitopes in a mouse model of experimental autoimmune uveitis (EAU). This study is to investigate our hypothesis that the IRBP_1-20-specific T cell response can be modulated by virus-mediated gene transfer. Methods: The IRBP_1-20 coding sequence is genetically fused to the ß chain of I-A^b, the only functional class II molecule in H-2^b mice, through a flexible linker. Recombinant adenovirus co-expressing B7-1, a T cell co-stimulatory molecule, and the covalent complex of IRBP_1-20/I-A^b was generated and characterized. IRBP_1-20-specific T cell activation was investigated both in vitro with IRBP_1-20-specific T cell lines and in vivo in H-2^b mice. Results: In vitro results revealed that IRBP_1-20-specific T cell lines can be activated by adenovirus co-expressing IRBP_1-20/I-A^b and B7-1, but not by control virus. In vivo studies indicated that adenovirus co-expressing IRBP_1-20/I-A^b and B7-1 can selectively activate IRBP_1-20-specific T cells, but not adenoviral antigens as specificity controls. However, the adenovirus expressing IRBP_1-20/I-A^b alone failed to activate peptide-specific T cells. Conclusions: These results suggest that co-expression of IRBP_1-20/I-A^b and B7-1 leads to peptide-specific T cell activation in a T cell receptor-guided fashion. This approach is potentially applicable to turn off EAU by down-regulating the peptide-specific T cell response in conjunction with inhibitory molecules, such as Fas ligand or programmed death-1 ligands.

Keywords: uveitis-clinical/animal model • gene transfer/gene therapy • autoimmune disease