Induction of antigen-specific Treg cells in treating autoimmune uveitis via bystander suppressive pathways without compromising anti-tumor immunity

Background: Induction of autoantigen-specific Treg cells that suppress tissue-specific autoimmunity without compromising beneficial immune responses is the holy-grail for immunotherapy to autoimmune diseases. Methods: In a model of experimental autoimmune uveitis (EAU) that mimics human uveitis, ocular inflammation was induced by immunization with retinal antigen interphotoreceptor retinoid-binding protein (IRBP). Mice were given intraperitoneal injection of alpha CD4 antibody (Ab) after the onset of disease, followed by administration of IRBP. EAU was evaluated clinically and functionally. Splenocytes, CD4(+)CD25 and CD4(+)CD25(+) T cells were sorted and cultured with IRBP or alpha CD3 Ab. T cell proliferation and cytokine production were assessed. Findings: The experimental approach resulted in remission of ocular inflammation and rescue of visual function in mice with established EAU. Mechanistically, the therapeutic effect was mediated by induction of antigen-specific Treg cells that inhibited IRBP-driven Th17 response in TGF-beta and IL-10 dependent fashion. Importantly, the Ab-mediated immune tolerance could be achieved in EAU mice by administration of retinal autoantigens, arrestin but not limited to IRBP only, in an antigen-nonspecific bystander manner. Further, these EAU-suppressed tolerized mice did not compromise their anti-tumor T immunity in melanoma model. Interpretation: We successfully addressed a specific immunotherapy of EAU by in vivo induction of autoantigen-specific Treg cells without compromising host overall T cell immunity, which should have potential implication for patients with autoimmune uveitis. (C) 2021 The Author(s). Published by Elsevier B.V.

Automated summary

This study successfully induced antigen-specific Treg cells in a model of experimental autoimmune uveitis, alleviating ocular inflammation without compromising beneficial immune responses. The therapeutic effect was mediated by inhibiting specific T cell responses, while maintaining overall T cell immunity in the host.