title: Endogenous cortisol and TGF-beta in human aqueous humor contribute to ocular immune privilege by regulating dendritic cell function.
abstract: Aqueous humor (AqH) has been shown to have significant immunosuppressive effects on APCs in animal models. We wanted to establish whether, in humans, AqH can regulate dendritic cell (DC) function and to identify the dominant mechanism involved. Human AqH inhibited the capacity of human peripheral blood monocyte-derived DC to induce naive CD4(+) T cell proliferation and cytokine production in vitro, associated with a reduction in DC expression of the costimulatory molecule CD86. This was seen both for DC cultured under noninflammatory conditions (immature DC) and for DC stimulated by proinflammatory cytokines (mature DC). DC expression of MHC classes I/II and CD83 was reduced (mature DC only). Myeloid DC from peripheral blood were similarly sensitive to the effects of human AqH, but only under inflammatory conditions. The addition of α-melanocyte stimulating hormone and vasoactive intestinal peptide did not cause significant inhibition at physiological levels. However, the addition of exogenous cortisol at physiological levels recapitulated the AqH-induced reduction in CD86 and inhibition of DC-induced T cell proliferation, and blockade of cortisol in AqH partially reversed its suppressive effects. TGF-β2 had an additional effect with cortisol, and although simultaneous blockade of cortisol and TGF-β2 in AqH reduced its effectiveness, there was still a cortisol- and TGF-β-independent component. In humans, AqH regulates DC maturation and function by the combined actions of cortisol and TGF-β2, a pathway that is likely to contribute to the maintenance of immune privilege in the eye.
authors.affiliation: Institute of Biomedical Research, School of Immunity and Infection, College of Medical and Dental Sciences, University of Birmingham, Birmingham and Midland Eye Centre, Birmingham, B15 2TT, United Kingdom.
authors.forename: Alastair K
authors.initials: AK
authors.lastname: Denniston
authors.forename: Sherine H
authors.initials: SH
authors.lastname: Kottoor
authors.forename: Imran
authors.initials: I
authors.lastname: Khan
authors.forename: Kadambari
authors.initials: K
authors.lastname: Oswal
authors.forename: Geraint P
authors.initials: GP
authors.lastname: Williams
authors.forename: Joseph
authors.initials: J
authors.lastname: Abbott
authors.forename: Graham R
authors.initials: GR
authors.lastname: Wallace
authors.forename: Mike
authors.initials: M
authors.lastname: Salmon
authors.forename: Saaeha
authors.initials: S
authors.lastname: Rauz
authors.forename: Philip I
authors.initials: PI
authors.lastname: Murray
authors.forename: S John
authors.initials: SJ
authors.lastname: Curnow
mesh_terms: D017951:Antigen Presentation / Q000276:immunology; D001082:Aqueous Humor / Q000276:immunology* / Q000378:metabolism; D002478:Cells, Cultured; D018920:Coculture Techniques; D003713:Dendritic Cells / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D005123:Eye / Q000276:immunology* / Q000378:metabolism; D006680:HLA Antigens / Q000096:biosynthesis; D015395:Histocompatibility Antigens Class I / Q000096:biosynthesis; D000949:Histocompatibility Antigens Class II / Q000096:biosynthesis; D006801:Humans; D006854:Hydrocortisone / Q000037:antagonists & inhibitors / Q000502:physiology*; D007108:Immune Tolerance; D008213:Lymphocyte Activation / Q000276:immunology; D015398:Signal Transduction / Q000276:immunology; D016176:T-Lymphocyte Subsets / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D053781:Transforming Growth Factor beta2 / Q000037:antagonists & inhibitors / Q000502:physiology*
chemical_list: D006680:HLA Antigens; D015395:Histocompatibility Antigens Class I; D000949:Histocompatibility Antigens Class II; D053781:Transforming Growth Factor beta2; D006854:Hydrocortisone