Expanding Antigen-Specific T-Regulatory Type 1 CD4+ T Cells in Vivo to Treat CNS Autoimmunity

Background: T-regulatory cells hold promise as targets for therapeutic intervention in autoimmunity, but approaches capable of expanding antigen-specific T-regulatory cells in vivo do not currently exist. We have discovered that systemic delivery of nanoparticles (NPs) coated with type 1 diabetes-relevant peptide-major-histocompatibility-complex (pMHC) class-II molecules triggers the formation and profound expansion of cognate T-regulatory-type-1 (TR1) CD4+ T-cells in vivo, including mice humanized with lymphocytes from patients, leading to resolution of pancreatic islet inflammation and restoration of normoglycemia in spontaneously diabetic mice. Here, we show that treatment of MOG- or PLP-immunized B6 and HLA-DR4-IE transgenic C57BL/6.Iab^nullmice with nanoparticles coated with disease-relevant pMHC class II molecules induces a systemic expansion and recruitment of cognate TR1 CD4+ T-cells to the CNS, blunting disease progression and restoration of motor function in paralytic mice.

Objectives: To demonstrate that the autoimmune process in EAE generates autoreactive memory-like CD4+ T cells with regulatory function that can be expanded by treating EAE mice with peptide-MHC class II-coated NPs, thus, affording therapeutic protection against cognate and non-cognate effector T cells.

Methods: EAE-relevant-pMHC class II complexes were expressed in lentivirus transduced CHO cells. Proteins secreted in the supernatant were purified using nickel columns and were directly coated on iron oxide NPs or were biotinylated to produce pMHC tetramers. EAE-induced mice were treated with pMHC-coated NPs, twice a week, for five weeks and disease scores were monitored regularly. At five weeks, cognate expansion of autoregulatory CD4+ T-cells and reduced inflammation, induced by NP therapy, was checked by flow cytometric analyses of pMHC class II tetramer+ cells and different histological staining, respectively. 

Results: pMHC-NP therapy was able to both blunt disease progression, when given at the onset of disease and restore motor function in paralytic mice when given at the peak of disease. These therapeutic effects were mirrored by weight gain, and were associated with systemic expansion of cognate TR1 CD4+ T-cells, significant reductions in macrophage/microglial infiltration in the cerebellum, decreased number of inflammatory foci and areas of demyelination in the cerebellum’s white matter and decreased demyelination of the spine.

Conclusions: These nanomedicines promote the differentiation of disease-primed autoreactive T-cells into TR1 cells, which in turn suppress autoantigen-loaded antigen-presenting cells, blunting disease progression, without compromising systemic immunity. pMHC class II-based nanomedicines thus represent a new class of drugs potentially useful for treating a broad spectrum of autoimmune phenomena in a disease-specific manner.