The role of miRNAs in stroke

Stroke is currently one of the leading causes of death and disability worldwide. Despite recent advances in the treatment of stroke there is a major unmet clinical need for novel therapeutics for intervention. miRNAs are small coding RNAs which act to post-transcriptionally inhibit expression of genes. Emerging evidence has supported the view that miRNAs play an important role in the development and progression of ischaemic stroke, although understanding remains relatively poor. This research uses several models to investigate the effects of miRNAs in the context of stroke in vivo and in vitro, as well as assessment of patient serum samples in order to identify biomarkers for stroke. miR-29b was found to be significantly upregulated in SHRSP rat brain peri-infarct at 72h following stroke, and downregulated in ischaemic core at 24h and 72h following stroke, whilst miR-29c was significantly downregulated in remainder tissue at 24h following stroke and in infarct at 72h following stroke. The upreglation of miR-29b at 72h corresponded to a significant downregulation of miR-29 target genes MMP2, MMP9 and TGF-β1 in peri-infarct tissue at 72h following stroke. Modulation of miR-29b and miR-29c was achieved in a rat neuronal cell line but suppression of genes of interest was not observed following oxygen glucose deprivation. Several candidate miRNAs were then identified by microRNA Openarray analysis in stroke patient serum samples. Validation of these miRNAs was not demonstrated in the population studied, but assessment of these miRNAs in rat serum and isolated exosomes demonstrated that several of these miRNAs were significantly altered in SHRSP rats following stroke. Finally miR-21 was demonstrated to be significantly upregulated in SHRSP rat peri-infarct following stroke. This was associated with a change in miR-21 localization as determined by in situ hybridization. Modulation of miR-21 via the use of CAG-miR-21 mice demonstrated no difference in infarct size as measured by T2 -weighted MRI scan nor was any difference present in behavioural tests versus wild type. KO of miR-21 resulted in a reduction of survival rate compared with wild type. This thesis demonstrates that miR-29 and miR-21 are modulated following stroke in animal models, and these are potential candidates for therapeutic intervention in the future. Analysis of clinical samples has illustrated difficulties in the identification of serum miRNA profiles and suggests that looking at the exosomal component of serum may provide better information regarding miRNA profiles after stroke.

A universally delivered CBT based intervention in a Scottish secondary school: a pilot feasibility study

Objectives: To evaluate the feasibility of a universally delivered CBT-based programme for pupils within a Scottish secondary school setting. Design: A pre-post, within and between groups design was utilised. Setting: Religious Moral Citizenship and Education (RMCE) classes in a Scottish secondary school. Participants: Four (n = 103) classes of third year secondary school pupils were arbitrarily allocated to two conditions: RMCE-as usual (RMCE-AU) controls, and LLTTF intervention. Intervention: Living Life to the Full (LLTTF) is a series of Cognitive Behavioural Therapy (CBT)-based booklets and accompanying 8 classes to improve coping skills. An adolescent version of LLTTF was recently developed. This was delivered over nine weeks by school teachers trained in the approach. Outcome measures: The Strengths and Difficulties Questionnaire, Rosenberg Self-Esteem scale, General Self-Efficacy Scale, and Locus of Control scale were administered at baseline and 9 week follow-up. To determine acceptability and utility of the materials course feedback was gathered weekly from the intervention group and a focus group (n=5) was conducted at 3 month follow up. Results: Outcome measures showed no significant improvement in overall wellbeing of those in the intervention group compared with that of the control group. Weekly feedback suggested that the majority of pupils found the materials useful and relevant. Focus group feedback suggested that pupils found the intervention useful, had utilised strategies in everyday life and would welcome recurring provision of such interventions within the school setting. Conclusions: Universally delivered CBT intervention is acceptable and feasible within the secondary school environment. However, objective measurement using standardised tools does not adequately corroborate qualitative feedback from pupils. Issues relating to measurement, study design and implementation of future interventions are discussed.