We are developing a novel immunomodulatory therapy, hR-411, to treat relapsing-remitting multiple sclerosis (RRMS). hR-411 restores regulatory T-cell balance by redirecting pathogenic Th1/Th17 cells into tolerance- inducing Tr1 cells. hR-411 is formed from the fusion of human Ig-Fc and CXCL11, a CXCR3-binding ligand that has been recently identified as a counter-regulatory chemokine. In contrast to the pro-inflammatory CXCR3- binding ligands CXCL9 and CXCL10, in vitro exposure of inflammatory effector Th1 and Th17 cells to CXCL11 redirects their polarization into anti-inflammatory Tr1 (FOXp3-CD25-IL-10high) cells. mR-411, the murine homologue of hR-411, profoundly suppresses the neurological and histologic findings of murine EAE, even when initiated after disease onset. The durability of this repolarization is shown in adoptive transfer studies wherein Ag-specific effector Th1 cells isolated from murine EAE donors treated in vivo with mR-411 suppress EAE in recipients with active disease. In contrast to general immunosupresants (steroids, rapamycin, calcineurin inhibitors), mR-411 induces tolerance that is Ag-specific for active disease yet preserves historical cell-mediated immunity to unrelated Ag's. Because CXCL11 interacts via the CXCR3 receptor, it is expected to bypass the CD46 defect in CD4+ cells in MS and fully activate IL-10 expression and induce Tr1 cell polarization. In support of this assumption, CXCL11 strongly induces IL-10 expression in human CD4+ cells co-incubated in vitro with anti-CD28. The purpose of this grant is to establish the pharmacodyamic profile of mR-411 in a classic murine EAE model of relapsing MS (""""""""R-EAE""""""""). The scientific hypothesis to be tested is that mR-411 decreases R-EAE by inhibiting the activation and differentiation of autoantigen-specific pro-inflammatory Th1/Th17 responses predominantly by promoting the activation of Tr1 cell function.
Aim #1 : Establish a pharmacodynamic profile of mR-411 in a murine model of R-EAE A titration of mR-411 (1, 3, or 10 mg/kg QOD IP) or an irrelevant IgG1 control will be tested in R-EAE, with groups of mice receiving treatment after the acute phase of disease (16-21 days). These treatment groups will be compared to a negative (sham) control group not exposed to PLP139-151, and a positive control group treated with dexamethasone. Animals will be monitored for overt neurological deterioration over a period of 1 month. Spinal cord tissue will be examined for histologic evidence of inflammation and tissue injury.
Aim #2 : Determination of the in vivo mechanism by which mR-411 decreases disease severity in R-EAE We will test the working hypothesis that mR-411 treatment decreases EAE disease severity by inhibiting the activation of autoantigen-specific Th1/Th17 effector responses. The same experimental paradigm will be employed as in Aim #1. We wil determine how mR-411 treatment alters the number, phenotype, induction, and function of CD4+ Th1/Th17 cells present within the CNS, spleen, and draining lymph nodes following treatment. These studies will use a combination of actively induced and transfer models of EAE employing myelin-specific 5B6 PLP139-151-specific TCR transgenic T cells.

Public Health Relevance

The proposed studies are designed to determine a putative mechanism by which treatment of mice with mR-411, a counter-regulatory tolerance-inducing chemokine fusion protein, may augment regulatory T cell function, thereby specifically suppressing the activity of autoreactive Th1/17 T cells in a mouse model of the relapsing remitting form of multiple sclerosis. This work has important implications for the etiology and treatment of multiple sclerosis.

National Institute of Health (NIH)
National Institute of Neurological Disorders and Stroke (NINDS)
Small Business Innovation Research Grants (SBIR) - Phase I (R43)
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Special Emphasis Panel (ZRG1-ETTN-C (11))
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Fertig, Stephanie
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Radikal Therapeutics, Inc.
West Tisbury
United States
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