Anti-DEC205 Mediated Delivery of Self-Antigen to Dendritic Cell Restores Tolerance in Spontaneous EAU

Abstract

Purpose: : Dendritic cells (DCs) play critical roles in the adaptive immune response participating both in immune activation and induction of tolerance. As an immunotherapy, DC "vaccination" has been used in patients with cancer for induction of immunity, but to date induction of tolerance for autoimmune disease is still at a preclinical stage. We have previously induced tolerance to IRBP by using antigen-pulsed immature DC and LPS-stimulated DC in a model of experimental autoimmune uveoretintitis (EAU). Here we have used a more targeted approach to induce tolerance by delivering antigenic peptide to different DC subsets using DC-selective antibody-peptide fusion proteins in a spontaneous model of EAU.

Methods: : 1.Spontaneous EAU mice was induced in B10.BR mice by crossing single Tg 3A9 TCR mice with Tg mice expressing hen egg lysozyme (HEL) in photoreceptor cells under control of the promoter for IRBP. 2.Anti-DEC205-HEL fusion protein and anti-33D1-HEL fusion proteins were purified by the transfection of expression vectors. 3. Targeting of the fusion proteins to DC after subcutaneous injection was confirmed by immunostaining and flow cytometry of draining lymph node cells. 4. Modulation of spontaneous EAU was evaluated clinically and histologically. 5. Induction/expansion of regulatory T cells in eye and lymph node after fusion protein treatment were measured by flow cytometry.

Results: : Anti-DEC205-HEL and anti-33D1 fusion proteins (5ug subcut) tracked selectively to DLN DC. Administration of anti-DEC205-HEL at d18 postnatal prevented development of EAU, which reached maximum levels at around d 30 in 100% of untreated mice. In contrast, anti33D1-HEL led to an acceleration of EAU development. Histological evaluation indicated that anti-DEC205-HEL markedly reduced the numbers of infiltrating effector CD4+ T cells in the eye, while CD4+CD25+FoxP3+ regulatory T cells in eye-draining lymph nodes were increased by anti-DEC205-HEL, but decreased by anti-33D1-HEL.

Conclusions: : Targeted delivery of antigen to specific DC subsets can promote tolerance or immunity depending on the DC specific surface molecule. Clinical trails in promoting immune response to tumour antigens are already in progress. The data presented here in a preclinical model reveal the potential for such therapy to regulate autoimmune disease.

Keywords: immunomodulation/immunoregulation • autoimmune disease • inflammation