title: IL-6 controls Th17 immunity in vivo by inhibiting the conversion of conventional T cells into Foxp3+ regulatory T cells.
abstract: The conditions leading to the induction of adaptive Foxp3(+) regulatory T cells (T-regs) from peripheral T cells in vivo are incompletely understood. Here, we show that unresponsiveness of T cells to IL-6 by T cell-selective deletion of gp130 or immunization of wild-type mice with antigen in incomplete Freund's adjuvant (IFA), which fails to induce IL-6, promotes the conversion of peripheral CD4(+) T cells into adaptive Foxp3(+) T-regs. Thus, both T cell-conditional gp130 knockout (KO) mice immunized with MOG35-55 in complete Freund's adjuvant (CFA) and wild-type mice immunized with MOG35-55 in IFA develop overwhelming antigen-specific T-reg responses and are protected from experimental autoimmune encephalomyelitis (EAE). Depletion of T-regs restores T helper (Th)17 responses and clinical EAE in MOG/CFA-immunized T cell-conditional gp130 KO mice, but not in MOG/IFA-immunized wild-type mice. We conclude that in the absence of T-regs, IL-6 signaling is dispensable for the induction of Th17 cells, and alternative pathways exist to induce Th17 cells and EAE in the absence of IL-6 signaling. However, IL-6 signaling is dominant in inhibiting the conversion of conventional T cells into Foxp3(+) T-regs in vivo, and in the absence of IL-6 signaling, no other cytokine can substitute in inhibiting T-reg conversion. These data identify IL-6 as an important target to modulate autoimmune responses and chronic inflammation.
authors.affiliation: Technische Universität München, Department of Neurology, Ismaninger Strasse 22, 81675 München, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Korn
authors.forename: Meike
authors.initials: M
authors.lastname: Mitsdoerffer
authors.forename: Andrew L
authors.initials: AL
authors.lastname: Croxford
authors.forename: Amit
authors.initials: A
authors.lastname: Awasthi
authors.forename: Valérie A
authors.initials: VA
authors.lastname: Dardalhon
authors.forename: George
authors.initials: G
authors.lastname: Galileos
authors.forename: Patrick
authors.initials: P
authors.lastname: Vollmar
authors.forename: Gretta L
authors.initials: GL
authors.lastname: Stritesky
authors.forename: Mark H
authors.initials: MH
authors.lastname: Kaplan
authors.forename: Ari
authors.initials: A
authors.lastname: Waisman
authors.forename: Vijay K
authors.initials: VK
authors.lastname: Kuchroo
authors.forename: Mohamed
authors.initials: M
authors.lastname: Oukka
mesh_terms: D000818:Animals; D004681:Encephalomyelitis, Autoimmune, Experimental / Q000276:immunology / Q000517:prevention & control; D051858:Forkhead Transcription Factors / Q000276:immunology*; D015850:Interleukin-6 / Q000096:biosynthesis / Q000502:physiology*; D051379:Mice; D018345:Mice, Knockout; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology*; D050378:T-Lymphocytes, Regulatory / Q000276:immunology*
chemical_list: D051858:Forkhead Transcription Factors; C498833:Foxp3 protein, mouse; D015850:Interleukin-6