Author Of 1 Presentation
LB1237 - An Antigen-Specific Microparticle Formulation Therapeutically Treats a Mouse Model of Multiple Sclerosis (ID 2121)
Abstract
Background
Experimental autoimmune encephalomyelitis (EAE) is a mouse model commonly used to study MS in vivo. We show that an antigen-specific microparticle (MP) system that delivers the autoantigen myelin oligodendrocyte glycoprotein (MOG35-55) along with granulocyte-macrophage colony-stimulating factor (GM-CSF), transforming growth factor beta-1 (TGF-β1), and vitamin D3 (VD3) can alleviate disease in B6 mice suffering from primary progressive EAE. GM-CSF serves as a recruitment chemokine to localize dendritic cells (DCs) to the injection site, while TGF-β1 and VD3 serve as tolerogenic factors to elicit a suppressive phenotype while autoantigen is presented.
Objectives
The objective of this study is to determine the efficacy and the mechanism of the dMP MOG35-55 treatment through the evaluation of clinical scores, immune cell phenotype, myelin differences, and response to opportunistic infection.
Methods
The VD3-loaded MPs and antigen-loadedMPs were fabricated to be phagocytized (1 µm), while TGF-β1-loaded MPs and GM-CSF-loaded MPs were fabricated to be non-phagocytosable (30-50 μm) allowing the release of factors extracellularly. These poly(lactic-co-glycolic acid) MPs were fabricated based on standard solvent evaporation techniques based on hydrophobicity. In vivo experiments: At the onset or peak of disease, a cocktail of VD3, TGF-β1, GM-CSF, and either OVA323-339 (irrelevant antigen) or MOG35-55 microparticles were injected subcutaneously in the middle of the back, with a 2nd injection 3 days later. Additionally, mice were challenged with a listeria monocytogenes infection following dMP treatment to test the antigen-specificity of this treatment. Of note, this experiment was conducted in non EAE induced mice.
Results
dMP MOG35-55 treatment was able to halt EAE at onset and reverse disease at peak. Flow cytometry showed dMP MOG35-55 treatment decreases MHC II expression compared to treatment with dMP OVA323-339 with both treatment at the onset and the peak of disease. Additionally, there were fewer CD8 T-cells, fewer cells expressing GM-CSF, and tbet in dMP MOG35-55 treated mice. Luxol fast blue staining for myelin sheath shows mice treated with dMP MOG35-55 had less demyelination in the lumbar spinal cord. Additionally, infected mice could clear the infection in a time consistent with health controls despite reaching the peak of infection faster.
Conclusions
In this study, we show that the dMP MOG35-55 formulation can halt or reverse EAE in an antigen-specific manner. The lack of demyelination and physical impairment can in part be attributed to a reduction in activated DCs and fewer cytotoxic T-cells in the CNS of dMP MOG35-55 treated mice compared to dMP OVA323-339 treated mice. A future direction will be to expand on CNS cell profiling using histological analysis.