Modulation of monocyte responses by progressive multiple sclerosis therapy.

Abstract

Multiple sclerosis (MS) is an immune-mediated neurodegenerative disorder that is distinguished by neuroinflammation and demyelination. MS is severely debilitating and remains the most common cause of disability arising from non-traumatic brain and CNS damage in adults. In its progressive phase there are no effective treatments, so new therapy options are an urgent research priority. Extensive work has been done on the role of the adaptive immune system in contributing to the disease pathology and on the effects of therapies targeting lymphocytes in relapsing-remitting MS. Fewer studies have examined innate immune cells in people with progressive MS. This thesis addresses that gap by profiling monocyte phenotype and function in response to new and repurposed drugs that may provide benefit in progressive MS. This was achieved by modelling the drugs’ effects in vitro using peripheral blood cells from people with progressive MS and healthy subjects.

Clozapine is an atypical antipsychotic with broad receptor affinity that is primarily used to treat refractory schizophrenia. In addition to is antipsychotic action through dopamine receptor (DR) D2, its broad neuro-immune receptor affinity is thought to dampen inflammatory responses in the CNS. This thesis highlights clozapine’s anti-inflammatory effect by demonstrating a reduction in the expression of pro-inflammatory cytokines that are associated with MS pathology in treated monocytes. Clozapine also induced a significant increase in the expression of D1. We observed that D1 expression changes happened alongside alterations to immune cell activity and that MS participant monocytes were much more susceptible to DR expression changes compared to healthy people. Together this data substantiates clozapine as a potential treatment for progressive disease.

MIS416 is a large, non-soluble microparticle suspension that induces nuclear factor kappa B (NFB) dependent cytokine induction. We show here that monocytes are key cytokine responder cells to MIS416 and explore the molecular mechanism by demonstrating its effects on transcription factor activity. Our data showing increased production of cytokines by MIS416 suggests a route of treatment efficacy through tolerisation mechanisms, and by reducing inflammation through upregulation of anti-inflammatory cytokines and negative feedback from pro-inflammatory cytokine release. Furthermore, we demonstrate how disease heterogeneity, phenotype, and genotype could significantly affect drug response outcomes in patients who received the drug as part of a phase 2 clinical trial.

Much of this work was done using new spectral cytometer technology. Its use allowed for the novel approach that enabled the subtraction of autofluorescent noise from out data, and we demonstrate its efficient functioning, ease of use, and utility in acquiring high dimensional datasets. The resulting large dataset allowed us the opportunity to interrogate it using bioinformatics tools, and we show their utility as adjunct tools to conventional methods of gating and statistical analysis. These analyses help demonstrate that monocytes are a heterogenous immune cell subset that is functionally distinct in people with progressive MS when compared to monocytes from healthy individuals.