On-target And Direct Depletion And Modulation Of Myelin-autoreactive CD4~+ And CD8~+ T Cells In EAE Mice By A Tolerogenic Nanoparticle

Background:Numerous nanomaterials have been reported in the treatment of multiple sclerosis?MS?or experimental autoimmune encephalomyelitis?EAE?.But most of these nanosclae theraputics deliver meylin antigens together with toxins or cytokines underlay the cellular uptake and induction of tolerogenic antigen-presenting cells by which indirectly inducing T cell tolerance.The main disadvantage is the uncertainty in inducing tolerogenic APCs in vivo due to their diverse types,tissue specificities and surface receptors.Inaccurate targeting can enhance the immune response and aggravate the disease.In the future,direct and on-target depletion and modulation of autoreactive T cells is worthy to investigate without the requirement of tolerogenic APCs induction.Purpose:This study focuses on the on-target and direct modulation of meylin-autoreactive T cells and combined use of multiple regulatory molecules by generating a tolerogenic nanoparticle.Methods:Polylactic-co-glycolic acid nanoparticles?PLGA-NPs?were fabricated as a biodegradable scaffold to co-coupling MOG_40-54/H-2D^b-Ig dimer,MOG_35-55/I-A^b multimer,anti-Fas,PD-L1-Fc and CD47-Fc on their surface and encapsulating TGF-?1 inside.The resulting 217-nm tolerogenic nanoparticles?tNPs?were administered i.v.into MOG_35-55-induced active EAE mice and followed by the investigation of therapeutic outcomes,tissue distribution and in vivo mechanism.Results:?1?Multipotent tolerogenic nanoparticles?tNPs?were successfully generated with correct phenotypes and sustained release,and presented a mean diameter of 217nm;?2?Four infusions of the tNPs durably ameliorated EAE with a marked reduction of clinical score,neuroinflammation,demyelination and the infiltrartion of inflammatory cells and T cells in central nervous system;?3?tNPs could distribute in various organs with a retention of 36 hours and break through the blood-brain barrier into the brain tissue of EAE mice.Immunofluorescence staining also confirmed the presence of tNPs in the cerebral cortex regions and their contacts with T cells;?4?tNPs displayed many contacts with CD4⁺and CD8⁺T cells in spleen section,few intake by macrophages and DCs;?5?tNPs treatment markedly faciliated T cell apoptosis,inhibited T cell proliferation,and thus powerfully decreased the frequencies of MOG_35-55-reactive Th1 and Th17 cells and MOG_40-54-reactive Tc1 and Tc17 cells in spleen,but enhance the proliferation of regulatory T cells.Meanwhile,inhibitory cytokines like TGF-?1 and IL-10 were also up-regulated in the homogenates of central nervous system and supernatant of spleen cells.Conclusion:The tolerogenic nanoparticles carrying 5 kinds of immune molecules can directly and selectively modulate autoreactive T cells by surface presentation of multiple ligands and paracrine release of cytokine,and lead to the durable amelioration of EAE.This study provides a novel antigen-specific immunotherapy for the T cell-mediated autoimmune diseases.