A red blood cell-based antigen delivery system to facilitate T cell epitope presentation to induce peripheral tolerance to ADAMTS13 in immune-mediated TTP

ABSTRACT: Aims Leveraging the tolerogenic nature of their natural clearance pathway, we aim to exploit red blood cells (RBCs) as an antigen delivery system to achieve persistent exposure to ADAMTS13-derived peptides, promoting antigen-specific attenuation of autoreactive CD4+ T cells and induction of regulatory T cells. Background Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is a rare and potentially fatal autoimmune disease caused by a severe ADAMTS13 functional deficiency mediated by autoantibodies targeting ADAMTS13. Despite high survival rates achieved with current treatments, approximately 40% of patients experience relapses. Ensuring longer-lasting recovery by restoring immune tolerance towards ADAMTS13 remains a significant unmet need. Conclusion(s) Our strategy offers a modular and effective method for targeting antigenic peptides to RBCs for transfusion. Antigen-decorated RBCs are efficiently phagocytosed by macrophages and facilitate the presentation of FINVAPHAR on MHC II molecules, giving macrophages the ability to target ADAMTS13-specific T cells. Based on our results we propose that RBCs loaded with ADAMTS13-derived peptides containing immunodominant T cell epitopes represent a promising strategy for promoting tolerance in patients with iTTP. Methods A fusion peptide comprising the TAT cell-penetrating peptide and an immunodominant ADAMTS13-derived T cell epitope (FINVAPHAR core sequence) was designed. Binding of the fusion peptide to RBCs was monitored by flow cytometry and Imagestream. To examine whether this approach can facilitate antigen-presentation on MHC II molecules, peptide-loaded RBCs were fed to macrophages, followed by isolation of HLA-DR-peptide complexes to study the presented peptide repertoire via mass spectrometry. Results We found that the fusion peptide binds to RBCs in a concentration-dependent manner. Peptide-bound RBCs were efficiently phagocytosed by macrophages. Mass spectrometric analysis revealed that phagocytosis of peptide-loaded RBCs by macrophages results in the presentation of FINVAPHAR-containing sequences of varying lengths on MHCII molecules from HLA-DRB1*11 donors, confirming functional antigen presentation

INSTRUMENT(S): timsTOF HT

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Macrophage

SUBMITTER: Stijn Groten  

LAB HEAD: Prof. Jan Voorberg, PhD

PROVIDER: PXD064980 | Pride | 2025-07-25

REPOSITORIES: Pride