Colitis in a transgenic mouse model of autoimmune uveitis may be induced by neoantigen presentation in the bowel.

Undifferentiated uveitis (intraocular inflammation, IOI) is an idiopathic sight-threatening, presumed autoimmune disease, accountable for ~ 10% of all blindness in the developed world. We have investigated the association of uveitis with inflammatory bowel disease (IBD) using a mouse model of spontaneous experimental autoimmune uveoretinitis (EAU). Mice expressing the transgene (Tg) hen egg lysozyme (HEL) in the retina crossed with 3A9 mice expressing a transgenic HEL-specific TCR spontaneously develop uveoretinitis at post-partum day (P)20/21. Double transgenic (dTg TCR/HEL) mice also spontaneously develop clinical signs of colitis at ~ P30 with diarrhoea, bowel shortening, oedema and lamina propria (LP) inflammatory cell infiltration. Single (s)Tg TCR (3A9) mice also show increased histological LP cell infiltration but no bowel shortening and diarrhoea. dTg TCR/HEL mice are profoundly lymphopenic at weaning. In addition, dTg TCR/HEL mice contain myeloid cells which express MHC Class II-HEL peptide complexes (MHCII-HEL), not only in the inflamed retina but also in the colon and have the potential for antigen presentation. In this model the lymphopenia and reduction in the absolute Treg numbers in dTg TCR/HEL mice is sufficient to initiate eye disease. We suggest that cell-associated antigen released from the inflamed eye can activate colonic HEL-specific T cells which, in a microbial micro-environment, not only cause colitis but feedback to amplify IOI.

Low-dose 2-deoxy glucose stabilises tolerogenic dendritic cells and generates potent in vivo immunosuppressive effects.

Cell therapies for autoimmune diseases using tolerogenic dendritic cells (tolDC) have been promisingly explored. A major stumbling block has been generating stable tolDC, with low risk of converting to mature immunogenic DC (mDC), exacerbating disease. mDC induction involves a metabolic shift to lactate production from oxidative phosphorylation (OXPHOS) and ß-oxidation, the homeostatic energy source for resting DC. Inhibition of glycolysis through the administration of 2-deoxy glucose (2-DG) has been shown to prevent autoimmune disease experimentally but is not clinically feasible. We show here that treatment of mouse bone marrow-derived tolDC ex vivo with low-dose 2-DG (2.5 mM) (2-DGtolDC) induces a stable tolerogenic phenotype demonstrated by their failure to engage lactate production when challenged with mycobacterial antigen (Mtb). ~ 15% of 2-DGtolDC express low levels of MHC class II and 30% express CD86, while they are negative for CD40. 2-DGtolDC also express increased immune checkpoint molecules PDL-1 and SIRP-1α. Antigen-specific T cell proliferation is reduced in response to 2-DGtolDC in vitro. Mtb-stimulated 2-DGtolDC do not engage aerobic glycolysis but respond to challenge via increased OXPHOS. They also have decreased levels of p65 phosphorylation, with increased phosphorylation of the non-canonical p100 pathway. A stable tolDC phenotype is associated with sustained SIRP-1α phosphorylation and p85-AKT and PI3K signalling inhibition. Further, 2-DGtolDC preferentially secrete IL-10 rather than IL-12 upon Mtb-stimulation. Importantly, a single subcutaneous administration of 2-DGtolDC prevented experimental autoimmune uveoretinitis (EAU) in vivo. Inhibiting glycolysis of autologous tolDC prior to transfer may be a useful approach to providing stable tolDC therapy for autoimmune/immune-mediated diseases.