Analysis of CNS tissue-specific Tregs and dendritic cells in T cell responses and autoimmunity (MUC7P.757)

Abstract

Abstract We assessed locally generated, locally acting peripheral regulatory T cells (pTregs) in retinal immune homeostasis and ability of retinal dendritic cells (DC) to support T cell activation/expansion within retina. We used transgenic (Tg) mice expressing beta-galactosidase (bgal mice) as retinal neo-self antigen, TCR Tg mice (BG2) specific for bgal, and mice with labeled, depletable Tregs or DC, based on expression of diphtheria toxin (DTx) receptor and/or GFP controlled by FoxP3 or CD11c promoter (FDG or CDG mice). Treg and DC depletion from retina was done by DTx injection into the eye. T cells and DC were assayed by FACS of retina or blood. Retinal autoimmunity was assessed by histological analysis. After bgal (FDG/bgal mice) or IRBP (FDG mice) immunization, Treg depleted retinas showed increased incidence and severity of autoimmunity. We found local depletion of Tregs from retina sufficient to induce spontaneous autoimmunity in FDG/bgal/BG2 mice but not in single or double Tg mice. Dose of DTx used to eliminate retinal Tregs did not induce retinal autoimmunity if given systemically. DC depletion from the retina prevented Treg and Teff generation within retina after bgal injection. Retinal microglia remaining after DC depletion did not make up for the loss of DC-dependent antigen presentation. We conclude local Tregs within the retina protect against spontaneous organ-specific autoimmunity and local DC must be present within the retina for antigen presentation to T cells.