title: Foxp3+ CD25+ CD4+ natural regulatory T cells in dominant self-tolerance and autoimmune disease.
abstract: Naturally arising CD25+ CD4+ regulatory T (Treg) cells, most of which are produced by the normal thymus as a functionally mature T-cell subpopulation, play key roles in the maintenance of immunologic self-tolerance and negative control of a variety of physiological and pathological immune responses. Natural Tregs specifically express Foxp3, a transcription factor that plays a critical role in their development and function. Complete depletion of Foxp3-expressing natural Tregs, whether they are CD25+ or CD25-, activates even weak or rare self-reactive T-cell clones, inducing severe and widespread autoimmune/inflammatory diseases. Natural Tregs are highly dependent on exogenously provided interleukin (IL)-2 for their survival in the periphery. In addition to Foxp3 and IL-2/IL-2 receptor, deficiency or functional alteration of other molecules, expressed by T cells or non-T cells, may affect the development/function of Tregs or self-reactive T cells, or both, and consequently tip the peripheral balance between the two populations toward autoimmunity. Elucidation of the molecular and cellular basis of this Treg-mediated active maintenance of self-tolerance will facilitate both our understanding of the pathogenetic mechanism of autoimmune disease and the development of novel methods of autoimmune disease prevention and treatment via enhancing and re-establishing Treg-mediated dominant control over self-reactive T cells.
authors.affiliation: Department of Experimental Pathology, Institute for Frontier Medical Sciences, Kyoto University, Kyoto, Japan. shimon@frontier.kyoto-u.ac.jp
authors.forename: Shimon
authors.initials: S
authors.lastname: Sakaguchi
authors.forename: Masahiro
authors.initials: M
authors.lastname: Ono
authors.forename: Ruka
authors.initials: R
authors.lastname: Setoguchi
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Yagi
authors.forename: Shohei
authors.initials: S
authors.lastname: Hori
authors.forename: Zoltan
authors.initials: Z
authors.lastname: Fehervari
authors.forename: Jun
authors.initials: J
authors.lastname: Shimizu
authors.forename: Takeshi
authors.initials: T
authors.lastname: Takahashi
authors.forename: Takashi
authors.initials: T
authors.lastname: Nomura
mesh_terms: D000818:Animals; D001327:Autoimmune Diseases / Q000276:immunology* / Q000628:therapy; D015704:CD4 Antigens / Q000032:analysis; D051858:Forkhead Transcription Factors / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D008213:Lymphocyte Activation; D051379:Mice; D015375:Receptors, Interleukin-2 / Q000032:analysis*; D017634:Self Tolerance; D050378:T-Lymphocytes, Regulatory / Q000166:cytology / Q000187:drug effects / Q000276:immunology*
chemical_list: D015704:CD4 Antigens; C418974:FOXP3 protein, human; D051858:Forkhead Transcription Factors; D015375:Receptors, Interleukin-2