title: CD4+CD25+ T regulatory cells induced by LPS-activated bone marrow dendritic cells suppress experimental autoimmune uveoretinitis in vivo.
abstract: BACKGROUND
  Tolerance-inducing DC are considered to be less mature than immunogenic DC, but the conditions promoting a less mature DC phenotype are not clear. We have previously shown that lipopolysaccharide (LPS) can have differential effects on DC function depending on the timing of DC exposure to LPS. Here, we show that early LPS-activated bone marrow derived DC (early DC, eDC), when administered subcutaneously to mice in vivo, promote tolerance to EAU induced via immunisation with interphotoreceptor retinol binding protein (IRBP) peptide 161-180. The effect correlates with the failure of eDC to secrete IL-12, and appears to be mediated in part via expansion of naturally occurring CD4+ CD25+ T regulatory cells (Tregs), which also mediate suppression of EAU on adoptive transfer to naive mice followed by immunization with autoantigen.
  
  
  METHODS
  Immature DC were prepared from BMDC cultures. Early DC (eDC) and late DC (lDC) for tolerance experiments were obtained by differential timing of LPS addition and their cytokine secretion profile was analyzed. eDC and lDC were subcutaneously injected into mice. From the dLN CD4+ CD25+ GITR+ T regulatory cells found to express FoxP3 were isolated and transferred into mice prior to immunisation with IRBP. The immune response was scored by histopathology. Tregs were characterized in vitro by intracellular staining, cytokine secretion assay and transwell experiments.
  
  
  RESULTS
  eDC secrete IL-10 but no IL-12 or IFNgamma. When injected subcutaneously into naive mice, they expand the population of CD4+ CD25(+high) GITR+ T cells expressing FoxP3 in the dLN, thus increasing the total number of IL-10 producing cells. eDC induced Tregs inhibit CD4+ CD25- T effector cell proliferation by a contact dependent process, and both eDC and Tregs suppress retinal damage when adoptively transferred.
  
  
  CONCLUSIONS
  We suggest that DC maturation may be necessary for both tolerance and immunity, but differential levels of activation and/or cytokine production direct the outcome of DC-T cell interaction and this is determined by IL-12 production. T regulatory cells induced in vivo by contact with eDC are able to suppress disease in the EAU model by adoptive transfer.
authors.affiliation: Department of Ophthalmology, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25, 2ZD, UK. kirsten.siepmann@web.de
authors.forename: Kirsten
authors.initials: K
authors.lastname: Siepmann
authors.forename: Sabine
authors.initials: S
authors.lastname: Biester
authors.forename: Jarmila
authors.initials: J
authors.lastname: Plsková
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Muckersie
authors.forename: Linda
authors.initials: L
authors.lastname: Duncan
authors.forename: John V
authors.initials: JV
authors.lastname: Forrester
mesh_terms: D019264:Adoptive Transfer; D000818:Animals; D001327:Autoimmune Diseases / Q000276:immunology / Q000473:pathology / Q000517:prevention & control*; D001854:Bone Marrow Cells / Q000166:cytology*; D015704:CD4 Antigens / Q000276:immunology; D003713:Dendritic Cells / Q000276:immunology*; D004195:Disease Models, Animal; D005136:Eye Proteins; D051858:Forkhead Transcription Factors / Q000378:metabolism; D007108:Immune Tolerance; D016753:Interleukin-10 / Q000378:metabolism; D053645:Interleukin-2 Receptor alpha Subunit / Q000276:immunology; D008070:Lipopolysaccharides; D008198:Lymph Nodes / Q000166:cytology; D008213:Lymphocyte Activation; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D012173:Retinitis / Q000276:immunology / Q000473:pathology / Q000517:prevention & control*; D012177:Retinol-Binding Proteins; D050378:T-Lymphocytes, Regulatory / Q000502:physiology*; D014605:Uveitis / Q000276:immunology / Q000473:pathology / Q000517:prevention & control*; D000099214:Retinol-Binding Proteins, Interstitial
chemical_list: D015704:CD4 Antigens; D005136:Eye Proteins; D051858:Forkhead Transcription Factors; D016753:Interleukin-10; D053645:Interleukin-2 Receptor alpha Subunit; D008070:Lipopolysaccharides; D012177:Retinol-Binding Proteins; D000099214:Retinol-Binding Proteins, Interstitial; C498833:Foxp3 protein, mouse