T cell-expressed proprotein convertase furin is essential for maintenance of peripheral tolerance

Furin is a proprotein convertase induced in activated T cells, reported to processes the anti-inflammatory cytokine TGFb-1. Herein, we show that conditional deletion of furin in T cells allowed for normal T cell development but impaired the function of regulatory T cells and effector cells, which produced less TGFb-1. Furin-deficient Treg cells, were less protective in a T cell transfer colitis model and failed to induce Foxp3 in normal T cells. Furin-deficient effector cells were inherently overly active and were resistant to suppressive activity of wild-type Tregs. Thus, our results indicate that furin is indispensable in maintaining peripheral tolerance, which is due, at least in part, to its nonredundant, essential function in regulating TGFb-1 production. Targeting furin has emerged as a strategy in malignant and infectious disease. The current work suggests that inhibiting furin might activate immune responses, but may result in a breakdown in peripheral tolerance. Naive CD4+ CD62L+ CD44- T cells were isolated from Fur flox/flox and CD4 cre Fur flox/flox mice. Replicated samples were achieved for wild type and knockout conditions.