The effect of clozapine and MIS416 on demyelination, remyelination and immunomodulation in the murine cuprizone model

Multiple Sclerosis (MS) is a disorder of the central nervous system that affects approximately 2.5 million people worldwide. Due to the heterogeneous nature of the disease, and the want of an identified cause, treatment of MS remains difficult. Treatments are available, however these are limited in efficacy and are not suitable for all forms of MS. Disease pathology is characterised by the formation of demyelinating lesions in the central nervous system (CNS) which lead to cognitive and motor impairments associated with the disease. These CNS lesions can be classified as those with immune cell involvement or those without immune cell infiltrate, which are more commonly seen in progressive forms of MS, and currently, there are no treatments available for progressive MS.  Due to the limited options available for treating progressive MS, this thesis aims to identify the therapeutic effect provided by the immunomodulatory compounds, MIS416 and clozapine, in a non-immune mediated model of MS, which is believed to more closely resemble progressive disease. Both of these compounds have been shown previously to reduce disease burden in an immune-driven animal model of MS. To investigate the effect of immune-modulating therapies on lesions without immune cell infiltrate, the cuprizone model of non-immune demyelination was used.  In summary, the work presented in this thesis found that treatment with MIS416 and clozapine led to improved performance on behavioural assays, although neither agent inhibited cuprizone-induced demyelination or enhanced remyelination. The cellular mechanism behind the observed behavioural improvement is yet to be confirmed. MIS416 was able to maintain its previously identified immunomodulatory properties when administered in this novel setting. Moreover, novel changes to serum growth factors were identified that could provide unexpected benefit to MS patients administered MIS416. In addition to reversing cuprizone-induced behavioural deficits, clozapine reduced LPS-driven inflammatory cytokine production by microglia, indicating that clozapine has the ability to directly reduce inflammation, which may benefit progressive MS patients.   Protective effects provided by either of these compounds could aid in the development of unique combination therapies to target both the inflammatory immune component and the cellular components seen at different stages of MS. MIS416 induced changes to serum cytokines and growth factors in the periphery could be harnessed to treat not just MS but other auto-immune diseases characterised by a similar cytokine profile.