007) (Fig. 4B). Histological analysis did not reveal any differences

in CNS pathology between knockout and control groups with severe Decitabine mw mononuclear cell infiltrate and axonal demyelination in CNS lesions in both groups (not shown). These studies suggest that Mog expression is regulated by AIRE and this can influence the development of MOG35–55-induced EAE. As a therapeutic strategy that is in line with our previous studies 29, we asked whether AIRE-induced MOG expression in chimeric mice following transplantation of Aire transduced BM would prevent or reduce the development of EAE. Cohorts of lethally irradiated C57BL/6 mice were transplanted with non-manipulated BM cells or BM cells transduced with BVD-523 mouse either pAire, pProII or pMog retrovirus. Ten weeks after transplantation, mice were immunised with MOG35–55 peptide and monitored for EAE development. Chimeric mice ectopically expressing AIRE had a significantly delayed initiation and progression of EAE compared to control groups (Aire versus ProII, p=0.009; versus nBMT, p=0.002; versus WT control, p=0.001) (Fig. 4C). There was no difference between the control groups (all p values>0.2) except for the positive control group that ectopically expressed MOG directly and did not develop EAE (Aire versus Mog, p=0.002). The absence of EAE in MOG chimeric mice confirms our published data that mice transplanted with Mog-transduced BM are resistant to EAE induction

29. These observations suggest that ectopic expression of AIRE promotes elevated levels of MOG expression in BM derived cells and

that this can delay the development of EAE following MOG35–55 immunisation. The ability to genetically manipulate the BM compartment and promote ectopic Exoribonuclease antigen expression and immune tolerance has been demonstrated in a number of settings 26–28, 40. We have recently shown that transduced BM cells encoding Mog led to ectopic expression of MOG in BM-derived cells and immune tolerance with complete resistance to EAE induction 29. It is well established that the transcription factor AIRE is associated with the expression of a large array of TRA in the thymus 4, 5 and to a lesser extent in the periphery 13. Furthermore, mice and humans lacking AIRE have a greater incidence of autoimmune conditions 4, 17–19. We therefore asked whether the ectopic expression of AIRE could be used to promote the ectopic expression of target autoantigens and whether this could influence the susceptibility to MOG-induced EAE. While AIRE expression in vivo is predominantly restricted to thymic medullary cells, it has also been detected outside the thymus in dendritic cells and peripheral lymphoid organs 13, 16. Following the in vitro transduction of a number of cell lines of thymic, dendritic cell and macrophage origin with an Aire-encoding retrovirus, we observed that indeed the expression of TRA was upregulated in an AIRE-dependent manner.