Project description:Thymic medullary epithelial cell (mTEC) expression of the autoimmune regulator AIRE, and of tissue-specific antigens, is controlled by members of the non-canonical NF-kB signalling pathway, including RelB and NF-kB2. Of the genes in this pathway, RelB-/- mice develop a particularly severe multi-organ autoimmune syndrome, resembling Foxp3-deficiency. RelB-/- mice have medullary atrophy and few mTECs but the mechanism is unknown. We show that RelB is required for expression of medullary chemokines and mTEC AIRE, selection of a diverse peripheral T cell repertoire, and for peripheral Foxp3+ Treg function. Vβ families of T cells infiltrating diseased peripheral organs and thymic Treg were similarly skewed. Surprisingly, medullary atrophy results from intra-thymic granulocyte infiltration, consequent upon the Th2-mediated autoimmune disease. Dominant tolerance corrects thymic inflammatory disease and loss of thymic function. We demonstrate a reversible RelB-dependent inflammatory mechanism for loss of central tolerance associated with medullary atrophy. Thymi from 4 RelB+/- mice and 3 RelB-/- mice were profiled by microarays