Treatment with an Antigen-Specific Dual Microparticle System Reverses Advanced Multiple Sclerosis in Mice

Antigen-specific therapies hold promise for treating autoimmune diseases such as multiple sclerosis while avoiding the deleterious side effects of systemic immune suppression. In this study, an antigen-specific dual-sized microparticle (dMP) immunotherapy reversed hind limb paralysis when administered in mice with advanced experimental autoimmune encephalomyelitis (EAE). Treatment reduced central nervous system (CNS) immune cell infiltration, demyelination and inflammatory cytokine levels. Mechanistic insights using single-cell RNA sequencing showed that treatment impacted the MHC II antigen presentation pathway in dendritic cells, macrophages, B cells and microglia, not only in the draining lymph nodes, but strikingly also in the spinal cord. CD74 and cathepsin S were among the common genes downregulated in most antigen presenting cell (APC) clusters, with B cells also having numerous MHC II genes reduced. Efficacy of the treatment diminished when B cells were absent, suggesting their impact in this therapy, in concert with other immune populations. Activation and inflammation were reduced in both APCs and T cells. This promising antigen-specific therapeutic approach advantageously engaged essential components of both innate and adaptive autoimmune responses, and capably reversed paralysis in advanced EAE without the use of broad immunosuppressant. Significance Statement Multiple sclerosis (MS) is a debilitating autoimmune disease that can lead to paralysis. We demonstrate an antigen-specific microparticle treatment can reverse hind limb paralysis when administered in advanced EAE. Single-cell RNA-sequencing and flow cytometry analysis provide evidence the treatment acts by diminishing Ag presentation in APCs, including B cells in the CNS and the draining lymph nodes. Thus, the antigen-specific dual-sized microparticle treatment is a promising therapy even in advanced EAE, and potentially MS. ### Competing Interest Statement BGK is a founder, holds stock and serves on the scientific advisory board of Inspira Therapeutics, Inc. The University of Florida has filed patents related to the technology reported in this paper.