The pivotal role of Treg has been revealed in various animal models for inflammatory diseases [31–33] and mutations in the FoxP3 gene lead to the development of the fatal autoimmune disorder immunodysregulation polyendocrinopathy enteropathy X-linked (IPEX) syndrome (or scurfy phenotype in mice), that results in systemic autoimmunity [39–41]. Here, FOXP3 is linked to autoimmune disease.