A genetic method specifically delineates Th1-type Treg cells and their roles in tumor immunity
Masaaki Okamoto, Miwa Sasai, Ayumi Kuratani, Daisuke Okuzaki, Masaya Arai, James B. Wing, Shimon Sakaguchi, Masahiro Yamamoto
Abstract
Regulatory T (Treg) cells expressing the transcription factor (TF) Foxp3 also express other TFs shared by T helper (Th) subsets under certain conditions. Here, to determine the roles of T-bet-expressing Treg cells, we generate a mouse strain, called VeDTR, in which T-bet/Foxp3 double-positive cells are engineered to be specifically labeled and depleted by a combination of Cre- and Flp-recombinase-dependent gene expression control. Characterization of T-bet + Foxp3 + cells using VeDTR mice reveals high resistance under oxidative stress, which is involved in accumulation of T-bet + Foxp3 + cells in tumor tissues. Moreover, short-term depletion of T-bet + Foxp3 + cells leads to anti-tumor immunity but not autoimmunity, whereas that of whole Treg cells does both. Although ablation of T-bet + Foxp3 + cells during Toxoplasma infection slightly enhances Th1 immune responses, it does not affect the course of the infection. Collectively, the intersectional genetic method reveals the specific roles of T-bet + Foxp3 + cells in suppressing tumor immunity.