THE EFFECTS OF THE PROTEOGLYCAN ANTAGONIST SURFEN ON ANIMAL MODELS OF DEMYELINATION WITH COMPARISON TO IN VITRO T CELL AND MACROPHAGE RESPONSES

Abstract

Multiple sclerosis (MS) is a debilitating neurodegenerative disorder that currently affects over 3000 Nova Scotians, and is characterized by the autoimmune-mediated destruction of myelin and axons in the central nervous system. Symptoms include loss of balance, impaired vision or speech, fatigue, and paralysis. Connective tissue components such as proteoglycans are known to be major inhibitors of remyelination and are found at the border of active demyelinating MS lesions. This thesis sought to characterize the immunomodulatory properties of the proteoglycan antagonist surfen (bis-2-methyl-4-amino-quinolyl-6-carbamide) using both in vitro and in vivo models relevant to the study of MS. Surfen decreased murine T cell proliferation whether activated in vitro by co-stimulation with anti-CD3/anti-CD28-coated T cell expander beads or in vivo by injecting mice with anti-CD3 antibody (Chapter 3). We extended these studies to two murine models that mimic aspects of MS. In the Experimental Autoimmune Encephalomyelitis (EAE) model, surfen treated mice displayed a reduction in clinical scores that were associated with decreased cellular infiltration of both CD45+CD3+CD4+ T cells (spinal cord and cerebellum) and F4/80+CD11b+ myeloid cells (spinal cord; Chapter 4). Several potential mechanisms of action for surfen were identified including the selective regulation of T cell effector functions, decreased production of chemotactic cytokines that facilitate cellular infiltration, and a marked reduction in proteoglycan mRNA expression that positively correlated with clinical improvement. When these in vivo results were compared in vitro to murine bone-marrow derived macrophages (BMDMs), surfen produced a similar decrease in chemokine concentrations. Reductions in the pro-inflammatory mediators Interleukin (IL)-6, Tumor Necrosis Factor (TNF), and Nitric Oxide (NO) were also observed in BMDMs. Surfen produced a selective increase in the pro-inflammatory cytokine IL-12p40 in EAE, and IL-1β in BMDMs, suggesting that surfen has immunomodulatory capabilities that are likely mediated by macrophages. In contrast to EAE, surfen delayed remyelination when administered directly into a demyelinated lesion created by injecting lysolecithin into the corpus callosum of the murine brain, an effect associated with worsening disease (Chapter 5). The opposing effects of surfen observed in EAE and the lysolecithin model imply differing effects of proteoglycans on the inflammatory and repair-remyelination phases of MS.