title: Foxp3+CD25+ T regulatory cells stimulate IFN-gamma-independent CD152-mediated activation of tryptophan catabolism that provides dendritic cells with immune regulatory activity in mice unresponsive to staphylococcal enterotoxin B.
abstract: Mice made unresponsive by repeated injection of staphylococcal enterotoxin B (SEB) contained SEB-specific CD25(+)CD4(+)TCRBV8(+) T cells that were able to transfer their state of unresponsiveness to primary-stimulated T cells. About one-half of these cells stably up-regulated the expression of CD152. We undertook the present study to determine whether CD152(high) cells seen in this system were T regulatory cells responsible for suppression or whether they represented SEB-activated CD4(+) T effector cells. Our results show that, among SEB-specific TCRBV8(+) T cells isolated from unresponsive mice, all CD152(high)CD25(+)CD4(+) T cells expressed Foxp3, the NF required for differentiation and function of natural T regulatory cells. Moreover, suppression by CD25(+)CD4(+)TCRBV8(+) T cells was fully inhibited by anti-CD152 Abs. Following stimulation by soluble CD152-Ig, dendritic cells (DC) isolated from unresponsive mice strongly increased the expression and the function of indoleamine-2,3-dioxygenase (IDO), the enzyme responsible for the catabolism of tryptophan. This capacity to activate IDO was independent of IFN-gamma production by DC because CD152-Ig stimulation of DC isolated from SEB-treated IFN-gamma-deficient animals activated IDO expression and function. Finally, adding 1-methyl-tryptophan, an inhibitor of tryptophan catabolism, increased substantially the capacity of DC from unresponsive animals to stimulate primary T cell response toward SEB. Thus, we conclude that IFN-gamma-independent CD152-mediated activation of tryptophan catabolism by Foxp3(+)CD25(+) T regulatory cells provides DC with immune regulatory activity in mice unresponsive to SEB.
authors.affiliation: Institute for Medical Immunology, Université Libre de Bruxelles, Gosselies, Belgium.
authors.forename: Pascal
authors.initials: P
authors.lastname: Feunou
authors.forename: Sophie
authors.initials: S
authors.lastname: Vanwetswinkel
authors.forename: Florence
authors.initials: F
authors.lastname: Gaudray
authors.forename: Michel
authors.initials: M
authors.lastname: Goldman
authors.forename: Patrick
authors.initials: P
authors.lastname: Matthys
authors.forename: Michel Y
authors.initials: MY
authors.lastname: Braun
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000096:biosynthesis*; D000943:Antigens, Differentiation / Q000096:biosynthesis*; D015153:Blotting, Western; D060908:CTLA-4 Antigen; D002851:Chromatography, High Pressure Liquid; D003713:Dendritic Cells / Q000276:immunology*; D004768:Enterotoxins / Q000276:immunology*; D004789:Enzyme Activation; D005260:Female; D005434:Flow Cytometry; D051858:Forkhead Transcription Factors / Q000096:biosynthesis; D007108:Immune Tolerance / Q000502:physiology*; D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase / Q000378:metabolism; D007371:Interferon-gamma / Q000276:immunology; D053645:Interleukin-2 Receptor alpha Subunit / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D016176:T-Lymphocyte Subsets / Q000276:immunology; D050378:T-Lymphocytes, Regulatory / Q000276:immunology* / Q000378:metabolism; D014364:Tryptophan / Q000378:metabolism*
chemical_list: D015703:Antigens, CD; D000943:Antigens, Differentiation; D060908:CTLA-4 Antigen; C556707:Ctla4 protein, mouse; D004768:Enterotoxins; D051858:Forkhead Transcription Factors; C498833:Foxp3 protein, mouse; D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase; D053645:Interleukin-2 Receptor alpha Subunit; C031818:enterotoxin B, staphylococcal; D007371:Interferon-gamma; D014364:Tryptophan