title: Development of glycomolecules as novel therapeutics for the treatment of multiple sclerosis
Creators: name: McCanney, George Alexander
Publisher: name: University of Glasgow
Year: 2019
Subjects: subject: Heparan sulphate, Remyelination, CNS, multiple sclerosis.

description: Multiple sclerosis (MS) is an autoimmune disorder of the central nervous system (CNS), with the influx of immune cells resulting in focal inflammation and demyelination episodes. Demyelination in the CNS impairs the axon’s capacity to efficiently transmit nerve impulses via saltatory conduction and leaves the demyelinated axon susceptible to degeneration. Remyelination occurs through the migration of oligodendrocyte precursor cells (OPCs) into the lesion, the precursor cells then proliferate and differentiate to form a population of mature oligodendrocytes, which can then ensheath the denude axon. In the case of MS, the usually efficient and robust mechanism of remyelination is incomplete, contributing significantly to the pathology of the disease. Although there are currently several disease-modifying treatments available for the management of MS, these predominantly target the immune response and aim to reduce disease incidence and relapse. So therefore, compounds that promote remyelination could have potential as novel therapeutic agents, with clinical benefits to MS patients. Heparan sulphates (HS) are sulphated polysaccharides that act as modulators of cell signalling, by both sequestering ligands and acting as cofactors in the formation of ligand-receptor complexes. Previously, we have shown that HS mimetics generated by the desulphation of commercial heparin (mHeps) can influence astrocyte reactivity. Based on this effect and the reported activity of endogenous HS following CNS injury, we hypothesised that HS mimetics may enhance remyelination by modulating the injury environment. Therefore, this thesis aimed to explore how glycomolecules affect remyelination in vitro. Subsequently, the aims extended to investigating the potential mechanism-of-action behind any observed effect. To complete these aims we utilised an anti-MOG and complement mediated demyelinating culture (MC-Demy), which enabled the screening of a glycomolecule library, made up of a panel of mHeps, heparosans, ulvans, fucoidans and CX-01. It was identified that numerous low-sulphated HS mimetics promoted remyelination. This effect was not observed following treatment of the non-injured developmental myelinating culture (MC-Dev), thereby suggesting that HS mimetics exerted their effect through interacting with factors released after demyelination. The presence of inhibitory factors in the injury environment was validated through the treatment of MC-Dev cultures with conditioned media, which resulted in a decrease in myelination. Unbiased proteomics approaches were then used to investigate the factors present in the injury conditioned media, identifying the increased expression of several proteins already associated with CNS damage, such as CCL5, IL-1α, and TNF- α. Furthermore, to identify proteins that bind the HS mimetics, a mHep7 affinity pull-down was carried out, with protein analysis achieved by mass spectrometry and a Proteome Profiler array. This identified numerous interesting candidates, through which the low-sulphated HS mimetic treatments may promote remyelination. Of these protein hits, amyloid beta (1-42) peptide and CCL5 were validated as myelination inhibiting, demyelination secreted-mHep7 binding factors. The hypomyelination induced by amyloid beta (1-42) peptide and CCL5 treatments, in MC-Dev cultures, could be overcome with a mHep7 co-treatment. Therefore, we conclude that low-sulphated HS mimetics promote remyelination in vitro, via the modulation of multiple proteins released following demyelination. As such these compounds may have potential as novel therapeutics for MS.