The over-expression of Fra1 disorder the inflammatory cytokines secretion by mTEC of myasthenia gravis thymus

The thymus of a Myasthenia gravis (MG) patient is often accompanied effected with follicular hyperplasia. Inflammatory cytokines in thymus induce the formation of germinal centers(GC). MG thymic inflammatory cytokines are predominantly secreted by stromal cells. Our previous studies revealed that the expression level of the Fra1 protein, which is a Fos member of theActivator Protein 1 transcription factors (AP-1), was higher in the MG thymus compared with that of the normal thymus. Based on that, we demonstrated that Fra1 was mainly expressed in medulla thymic epithelial cells (mTECs) and that the rate of Fra1 positive mTECs in the MG thymus was higher than normal. In vitro, we found that the expression of CCL-5, CCL-19, CCL-21 could be regulated by Fra1 in mTEC, and that IL-1β, IL-6, IL-8 and ICAM1 were down-regulated in the Fra1 over-expression group and up-regulated in the Fra1 knock down group. Meanwhile, we detected that the expression levels of suppressor of cytokine signaling 3 (SOCS3) was significantly up-regulated along with the over-expression of Fra1. Hence, we considered that the over-expression of Fra1 disrupted inflammatory cytokine secretion by mTEC in the MG thymus, and that STAT3 and SOCS3 were strongly involved in this process. This article is protected by copyright. All rights reserved.