- Title
- Investigation of erythrocyte and erythrocyte-derived extracellular vesicle content and function in multiple sclerosis
- Creator
- Groen, Kira
- Relation
- University of Newcastle Research Higher Degree Thesis
- Resource Type
- thesis
- Date
- 2020
- Description
- Research Doctorate - Doctor of Philosophy (PhD)
- Description
- Multiple Sclerosis (MS) is an autoimmune disease of the central nervous system (CNS) for which there is no cure. It is widely accepted that pathogenic immune cells are activated in the periphery and gain access to the CNS via a damaged blood-brain barrier (BBB). Once in the CNS, immune cells cause demyelination and neurodegeneration. Diagnosis hinges on clinical evidence, magnetic resonance imaging, and detection of oligoclonal bands in patients’ cerebrospinal fluid. Additional biomarkers that enable a timely diagnosis and allow consistent monitoring are required to ensure early and adequate treatment. Erythrocytes may contribute to MS through altered haemorheological features and reduced antioxidant capacity, and their microRNAs may harbour biomarker potential. The role microRNAs play in translationally inactive erythrocytes remains unclear, yet they could be involved in intercellular communication through extracellular vesicles (EVs). Once released by their cell of origin, EVs can travel to recipient cells and deliver their cargo. Within the recipient cell, delivered microRNAs can then inhibit messenger RNA translation. An increase in plasma EVs has been observed in MS and sequencing of their microRNA profiles revealed increased miR-451a, an erythrocyte-enriched microRNA. Thus, erythrocyte-derived EVs may play a role in MS but EVs originating from other cells may also contribute to the pathophysiology. The aims of this thesis were to assess the biomarker potential of erythrocyte microRNAs, determine the potential function of erythrocyte microRNAs in MS by examining their target genes and packaging into erythrocyte-derived EVs, and investigate which other cells may contribute to altered intercellular communication through EVs. Erythrocyte microRNA profiles were sequenced and validated with a targeted assay in MS patients, healthy controls, and migraine patients. Biomarker potential was determined through receiver operating characteristic curves. Erythrocyte-derived EVs were created ex vivo and their microRNA profiles were sequenced. Targets of all differentially expressed and packaged microRNAs were predicted, and gene enrichment analysis was carried out. Platelet-free plasma samples were assessed by flow cytometry and EVs were enumerated using commercial counting beads. Expression of miR-183 cluster microRNAs, miR-96-5p, miR-182-5p, and miR-183-5p, was elevated in relapsing MS patient erythrocytes compared to healthy and pathological (migraine patients) controls. Both miR-182-5p and miR-183-5p could distinguish between MS patients and all controls with over 90% accuracy and around 90% specificity. MicroRNA-182-5p and miR-183-5p correlated with patients’ physical disability, and miR-96-5p correlated with patients’ cognitive disability. While the miR-183 cluster was not found to be differentially packaged into erythrocyte-derived EVs of MS patients, 34 other microRNAs were. Target prediction revealed several genes previously highlighted as putative MS susceptibility genes. In the plasma of MS patients, there was an increase in erythrocyte-derived EVs in relapsing patients. Yet, other cells also contributed to altered circulating EV levels. Platelet-, total leukocyte-, and T helper cell-derived EVs were decreased in relapsing patients, whereas endothelium-derived EVs were increased stable MS patients. Erythrocyte microRNAs harbour biomarker potential for MS that may provide assistance in ruling out other differentials, such as migraines. However, differences in erythrocyte microRNA expression were only detectable in active disease, which hinders their implementation. Both erythrocyte and erythrocyte-derived EV microRNAs may be involved in MS by targeting susceptibility genes. An enhanced understanding of the role erythrocyte microRNAs and EVs play MS, may lead to the discovery of novel therapeutic targets that may improve disease management and ultimately patients’ quality of life. Not only erythrocyte-derived EVs, but also EVs from other cells, such as T helper cells, platelets, and endothelial cells, may contribute to MS pathophysiology and could harbour biomarker potential. This thesis indicates that erythrocytes may be more than just respiratory gas carriers in MS. Their microRNAs’ potential involvement in MS is a novel finding that may help advance our understanding of the disease. A better understanding of MS pathophysiology is a crucial step in the search for a cure.
- Subject
- erythrocytes; microRNA; extracellular vesicle; multiple sclerosis; thesis by publication
- Identifier
- http://hdl.handle.net/1959.13/1433480
- Identifier
- uon:39262
- Rights
- Copyright 2020 Kira Groen
- Language
- eng
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