MS is an autoimmune neurodegenerative disease of the central nervous system (CNS) in which the etiology is not well understood. Although, auto-aggressive CD4+ T cells play a central role, the breakdown of immune tolerance mechanisms that permits activation of naive myelin-specific T cells is considered an initial step in the pathogenesis of MS. A number of pivotal studies in rodent models have substantiated that Ag- specific Tregs have a significant role in modulating autoimmune CNS disease and can be highly effective at treating MS. Consequentially, there has been a major focus in developing protocols that stimulate Treg numbers and their function. Unfortunately, successful therapeutic use of Tregs has been limited by the lack of safe and effective Ag-specific protocols for isolation and expansion that are suitable for translation. The AAV gene transfer platform has clearly demonstrated that hepatocyte-restricted transgene expression from an optimized AAV vector can reliably induce immune tolerance to various therapeutic proteins. Importantly, tolerance is dependent on achieving and maintaining adequate hepatocyte-restricted transgene expression that induces Ag-specific CD4+CD25+FoxP3+ Tregs. Recently, we have successfully developed a clinically relevant Adeno-associated Virus (AAV) immunotherapy that is not only capable of preventing the development of EAE, but can also reverse the neurological symptoms of preexisting disease. This vector-based immunotherapy uses the full-length protein coding sequence of a myelin-derived protein, which abrogates the need to identify HLA/MHC specific epitopes, making this unique approach universally applicable. Mechanistically, this process is based on the induction of immunological tolerance mediated by antigen specific Tregs. We hypothesize that a persistent immunological tolerance, independent of MHC restrictions can be established against three immunogenic myelin proteins, simultaneously. That such tolerance is mediated by the induction and expansion of Ag-specific Tregs that can prevent development of and reverse existing disease in the EAE model of MS.
Aim 1 : Develop, optimize and compare in vivo performance of AAV-PLP and -MBP vectors, and assess functional suppression of Ag-specific Tregs Aim 2: Demonstrate that AAV immunotherapy vectors can prevent or ameliorate disease in genetically diverse strains of mice.
Aim3 : Determine the minimum effective vector (MEV) dose for abrogation of disease without an adverse immune response or hepatotoxicity.
Aim 4 : Establish a multi-vector / multi-gene immunotherapy platform.

Public Health Relevance

MS is a neuro-inflammatory autoimmune disease in which T cell driven inflammation leads to demyelination and damage of axons. The overall goal for is proposal is to develop a clinically relevant Adeno- associated virus (AAV) immunotherapy that will restore tolerance in an autoimmune setting such as Multiple Sclerosis (MS). We will show that our protocol will induce and expand antigen (Ag)-specific regulatory T-cells (Tregs) in vivo and independent of MHC or epitope restrictions.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Research Project (R01)
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Gene and Drug Delivery Systems Study Section (GDD)
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Esch, Thomas R
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University of Florida
Schools of Medicine
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Keeler, Geoffrey D; Kumar, Sandeep; Palaschak, Brett et al. (2018) Gene Therapy-Induced Antigen-Specific Tregs Inhibit Neuro-inflammation and Reverse Disease in a Mouse Model of Multiple Sclerosis. Mol Ther 26:173-183
Keeler, Geoffrey D; Markusic, David M; Hoffman, Brad E (2017) Liver induced transgene tolerance with AAV vectors. Cell Immunol :