The Animal Models Unit has employed a murine model of multiple sclerosis, experimental autoimmune encephalomyelitis (EAE), to focus on the mechanisms driving pathogenic autoreactivity and triggers of autoimmunity in the CNS as well as investigating new modalities to treat disease that could be extended to therapies in MS. The study of humanized transgenic mice as a model of T cell receptor/ antigen/MHC interactions relevant to autoimmunity within the CNS is one focus of the group. We have wrapped up the characterization of two strains of transgenic mice carrying myelin reactive TCRs, and shown that the strain with the higher expression of MHC class II molecules can spontaneously develop autoimmunity at a low rate, serving as one of only a handful of models of spontaneous autoimmunity currently available. Further investigations within these models have shown that substituting the cognate antigen with a more stimulatory peptide allows for greater disease development irrespective of factors such as autoreactive T cell precursor frequency. A manuscript is under preparation. The second focus of studies has been the investigation into new therapeutic approaches to treat autoimmune demyelination in the CNS using EAE. The first approach targets a reduction in the inflammatory component of the disease. In collaboration with John Hallenbeck of the Stroke Branch, NINDS, we have thus far shown that intranasal administration of the human cell adhesion molecule E selectin results in a tolerization process to this molecule. In the active induction model of EAE, E selectin tolerization pretreatment can reduce the incidence and severity of clinical symptoms once disease is induced. Moreover, preliminary studies also show a reduction in the severity of disease when E selectin is administered once disease has been established, emphasizing the therapeutic potential of this approach. Studies to identify the tolerogenic populations generated and their mechanisms of action in this model are ongoing. Thus far, E selectin-specific populations have been identified and antibodies to E selectin have been characterized. Transfer of T cells from E selectin tolerized animals modulate disease, supporting a role for E selectin-specific regulatory populations. A patent has been filed for this work. An extension of this work has been intranasal administration of E selectin in models of atherosclerosis and plaque rupture. Thus far, E selectin tolerized animals show less lipid deposition in the aortic arch compared to PBS tolerized animals. Histopathological and array analyses are currently underway, supported by an NINDS/NHLBI Bench to Bedside Proposal. A second study in collaboration with James Mitchell, NCI has been investigating the potential for a well characterized anti-oxidant to prevent or treat autoimmune demyelination in the EAE model. Studies suggest this antioxidant is protective against induction of EAE. Furthermore, transfer of myelin-reactive T cells into animals on anti-oxidant feed develop less severe disease compared to animals on control feed. This reduction in disease is also observed when animals are administered anti-oxidant feed at the onset of clinical symptoms, supporting both an immunomodulatory and neuroprotective role for antioxidants in treating autoimmune-driven CNS disease. A patent has been filed describing this work and studies are ongoing to determine the precise mechanisms involved.
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