title: Antagonistic nature of T helper 1/2 developmental programs in opposing peripheral induction of Foxp3+ regulatory T cells.
abstract: Recent studies have highlighted the importance of peripheral induction of Foxp3-expressing regulatory T cells (Tregs) in the dominant control of immunological tolerance. However, Foxp3(+) Treg differentiation from naïve CD4(+) T cells occurs only under selective conditions, whereas the classical T helper (Th) 1 and 2 effector development often dominate T cell immune responses to antigen stimulation in the periphery. The reason for such disparity remains poorly understood. Here we report that Th1/Th2-polarizing cytokines can potently inhibit Foxp3(+) Treg differentiation from naïve CD4(+) precursors induced by TGF-beta. Furthermore, antigen receptor-primed CD4(+) T cells are resistant to Treg induction because of autocrine production of IFNgamma and/or IL-4, whereas neutralizing IFNgamma and IL-4 not only can potentiate TGF-beta-mediated Foxp3 induction in vitro but can also enhance antigen-specific Foxp3(+) Treg differentiation in vivo. Mechanistically, inhibition of Foxp3(+) Treg development by Th1/Th2-polarizing cytokines involves the activation of Th1/Th2 lineage transcription factors T-bet and GATA-3 through the canonical Stat1-, Stat4-, and Stat6-dependent pathways. Using IFNgamma and IL-4 knockouts and retrovirus-mediated transduction of T-bet and GATA-3, we further demonstrate that enforced expression of the Th1/Th2 lineage-specific transcription factors is sufficient to block Foxp3 induction and Treg differentiation independent of the polarizing/effector cytokines. Thus, our study has unraveled a previously unrecognized mechanism of negative cross-regulation of Foxp3(+) Treg fate choice by Th1/Th2 lineage activities. In addition, these findings also provide an attainable explanation for the general paucity of antigen-triggered de novo generation of Foxp3(+) Tregs in the periphery.
authors.affiliation: Department of Immunology, University of Texas M. D. Anderson Cancer Center, Houston, TX 77030, USA.
authors.forename: Jun
authors.initials: J
authors.lastname: Wei
authors.forename: Omar
authors.initials: O
authors.lastname: Duramad
authors.forename: Olivia A
authors.initials: OA
authors.lastname: Perng
authors.forename: Steven L
authors.initials: SL
authors.lastname: Reiner
authors.forename: Yong-Jun
authors.initials: YJ
authors.lastname: Liu
authors.forename: F Xiao-Feng
authors.initials: FX
authors.lastname: Qin
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D016207:Cytokines / Q000037:antagonists & inhibitors / Q000502:physiology; D051858:Forkhead Transcription Factors / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D015398:Signal Transduction; D050378:T-Lymphocytes, Regulatory / Q000166:cytology / Q000276:immunology*; D018417:Th1 Cells / Q000166:cytology*; D018418:Th2 Cells / Q000166:cytology*
chemical_list: D016207:Cytokines; D051858:Forkhead Transcription Factors; C498833:Foxp3 protein, mouse