Myelin-reactive, TGF-β-induced regulatory T cells can be programmed to develop Th1-like effector function but remain less proinflammatory than myelin-reactive Th1 effectors and can suppress pathogenic T cell clonal expansion in vivo

J Immunol. 2010 Dec 15;185(12):7235-43. doi: 10.4049/jimmunol.1001551. Epub 2010 Nov 17.

Abstract

Interest in the use of regulatory T cells (Tregs) as cellular therapeutics has been tempered by reports of naturally occurring Tregs losing Foxp3 expression and producing IL-17, raising concerns over a switch to pathogenic function under inflammatory conditions in vivo. TGF-β-induced Tregs (inducible Tregs [iTregs]), generated in large numbers in response to disease-relevant Ags, represent the most amenable source of therapeutic Tregs. Using Foxp3-reporter T cells recognizing myelin basic protein (MBP), we investigated the capacity of iTregs to produce effector-associated cytokines under proinflammatory cytokine conditions in vitro and whether this translated into proinflammatory function in vivo. In contrast with naturally occurring Tregs, iTregs resisted conversion to an IL-17-producing phenotype but were able to express T-bet and to produce IFN-γ. iTregs initiated their T-bet expression during their in vitro induction, and this was dependent on exposure to IFN-γ. IL-12 reignited iTreg expression of T-bet and further promoted iTreg production of IFN-γ upon secondary stimulation. Despite losing Foxp3 expression and expressing both T-bet and IFN-γ, MBP-responsive IL-12-conditioned iTregs induced only mild CNS inflammation and only when given in high numbers. Furthermore, iTregs retained an ability to suppress naive T cell clonal expansion in vivo and protected against the development of experimental autoimmune encephalomyelitis. Therefore, despite bearing predictive hallmarks of pathogenic effector function, previously Foxp3(+) iTregs have much lower proinflammatory potential than that of MBP-responsive Th1 cells. Our results demonstrate that autoprotective versus autoaggressive functions in iTregs are not simply a binary relationship to be determined by their relative expression of Foxp3 versus T-bet and IFN-γ.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Central Nervous System / immunology
  • Central Nervous System / metabolism
  • Central Nervous System / pathology
  • Cytokines / genetics
  • Cytokines / immunology
  • Cytokines / metabolism
  • Encephalomyelitis, Autoimmune, Experimental / genetics
  • Encephalomyelitis, Autoimmune, Experimental / immunology*
  • Encephalomyelitis, Autoimmune, Experimental / metabolism
  • Encephalomyelitis, Autoimmune, Experimental / pathology
  • Forkhead Transcription Factors / biosynthesis
  • Forkhead Transcription Factors / genetics
  • Forkhead Transcription Factors / immunology
  • Gene Expression Regulation / genetics
  • Gene Expression Regulation / immunology
  • Mice
  • Mice, Knockout
  • Myelin Basic Protein / genetics
  • Myelin Basic Protein / immunology*
  • Myelin Basic Protein / metabolism
  • T-Lymphocytes, Regulatory / immunology*
  • T-Lymphocytes, Regulatory / metabolism
  • T-Lymphocytes, Regulatory / pathology
  • Th1 Cells / immunology*
  • Th1 Cells / metabolism
  • Th1 Cells / pathology
  • Transforming Growth Factor beta / immunology*
  • Transforming Growth Factor beta / metabolism

Substances

  • Cytokines
  • Forkhead Transcription Factors
  • Foxp3 protein, mouse
  • Myelin Basic Protein
  • Transforming Growth Factor beta