Posters

Aphasia, a common consequence following stroke, involves the loss or impairment of language. It can affect speaking, comprehension, reading, and writing. Individuals with aphasia often experience a mismatch between the words they think or intend to say, and the words they can say aloud. We refer to thinking in words as ‘inner speech’ and it plays a role in cognitive functions such as planning and problem-solving. While there are tools for measuring inner speech in neurotypical populations, they are not designed for people with language difficulties. We adapted the Varieties of Inner Speech Questionnaire-Revised (VISQ-R) to make it accessible for individuals with aphasia. The adaptation process involved consultation with stroke survivors with aphasia, carers, speech and language therapists, and neurotypical adults. To evaluate its psychometric properties, 46 neurotypical adults completed both the original and adapted versions of the VISQ-R with a 14-day interval. The adapted version was then administered to 15 stroke survivors with aphasia. Results showed good internal consistency (Cronbach’s a = .80 - .90), and moderate-to-strong test-retest reliability (r = .58-.85 for the subscales; .72 for the overall score). Although some stroke survivors reported the questionnaire to be lengthy and some items’ wording to be repetitive, they were nevertheless able to engage meaningfully with the adapted items. The adapted VISQ-R is a reliable and accessible tool for assessing inner speech in post-stroke aphasia, potentially contributing to effective diagnosis and tailored rehabilitation plans.

Although stroke medicine advances and reperfusion treatments have improved survival rates, there remains a growing population of individuals with clinically relevant complications post-stroke. Around a third of individuals develop cognitive decline within five years, with the underlying mechanisms poorly understood. Stroke induces peripheral immune changes, which are proposed to influence cognitive outcomes. Yet, how these changes relate to metabolism is unclear. In the ongoing Stroke-IMPaCT cohort study at sites in the UK (Manchester) and the USA (Stanford and North Manhattan), peripheral blood was collected from patients within 96 hours of ischaemic stroke, as well as at 6-9 and 18-21 months, alongside detailed cognitive assessment. Following plasma isolation, untargeted metabolomics was performed on admission samples from a subset (n=75) of patients. The primary outcome was cognitive status at 18-21 months, derived from z-scores for several cognitive domains. The cohort was prominently male (73%), with a median age of 66 and median NIHSS score of 4. 48% of individuals were cognitively impaired at 18-21 months. Admission metabolic signatures could largely distinguish between cognitive status at 18-21 months via PLS-DA, with 138 metabolites important in driving this separation (VIP score > 1.5). A signature of ten of these metabolites produced an area under the curve of 0.85, demonstrating excellent ability to predict cognitive status. These metabolites included several species related to purine metabolism and phospholipid synthesis, as well as taurine. Thus, early post-stroke metabolite signatures show links to subsequent cognitive impairment, with ongoing analyses investigating relationships between these metabolites and peripheral immune status.

Spontaneous recovery following stroke typically occurs in the acute and sub-acute stages (up to 6 months post-stroke), with minimal improvements in the chronic stage thereafter. Better understanding how the neurochemical milieu changes throughout these recovery stages is critical for developing new therapies. However, conducting longitudinal human studies presents significant challenges due to stroke survivors' complex health needs. Magnetic Resonance Spectroscopy (MRS), a novel neuroimaging technique, may help bridge this gap, enabling non-invasive assessment of neurochemical changes across human and rodent studies. Here, we used MRS to quantify neurochemicals throughout stroke recovery in rats. Stroke was induced in the left striatum using endothelin-1 stereotaxic injections. We collected MRS data of excitatory and inhibitory neurotransmitters (glutamate, GABA) from the left motor cortex at four timepoints: baseline (before stroke) and 2-day, 7-day and 30-day post-stroke (n=7) or sham (n=7) interventions. We also collected sensorimotor behavioural measurements (grip force, gait and touch perception) at each timepoint. We found no significant differences in GABA and glutamate levels between the stroke and sham groups throughout recovery (GABA: F(1, 37)=1.030, p=0.317; glutamate: F(1,12)=0.899, p=0.362). As expected, we found a significant difference in grip force change between the stroke and sham groups (F(1, 12)=6.117, p=0.029), but these measurements did not significantly correlate with neurotransmitters changes. Analysis of gait and touch perception data is still ongoing, as is the optimisation of the MRS processing pipeline to remove artefacts and improve signal-to-noise ratios. Longitudinal studies using non-invasive techniques are key to enhance translation between rodent and human stroke studies.

Intraventricular haemorrhage (IVH) is a devastating subtype of haemorrhagic stroke, characterized by bleeding into the cerebrospinal fluid (CSF) filled ventricles of the brain. IVH is common in premature neonates due to bleeding from the germinal matrix, termed a germinal matrix haemorrhage (GMH). Approximately 45% of premature infants experience some grade of GMH/IVH, with up to 41% of these suffering complications, including post-haemorrhagic hydrocephalus (PHH), as a result. IVH (and PHH in particular) often lead to lifelong disability, poor quality of life and death. Current treatments for IVH are surgical and supportive in nature, but novel pharmacological treatments could significantly improve post-IVH outcomes in these patients. However, little is known about the underlying pathogenic molecular mechanisms, limiting our ability to effectively develop new therapeutics. Here, we utilised post-natal day 3 mouse pups injected intracerebroventricularly with blood; with RNA-sequencing, T2W MRI and immunohistochemistry performed on cortical tissue obtained 24 hours later. Transcriptomic analysis was performed to determine differentially expressed genes, gene ontology pathways, protein-protein interactions and transcription factor activity. Significant changes in antioxidant, extracellular matrix and ion channel related pathways were observed. We also studied the utility of the proteoglycan decorin (an endogenous antagonist to the cytokine transforming growth factor-β1 which is implicated in PHH development) as a treatment, observing modulation of genes related to blood product clearance via phagocytosis and autophagy. This study furthers our understanding of the pathological mechanisms and transcriptomic regulators affected by IVH, whilst also suggesting that decorin may enhance the clearance of blood products following IVH.

Previous studies have shown that neuronal reprogramming in vivo is more efficient in injured than in intact brains, suggesting that damage creates a permissive environment for glial lineage plasticity. Consistent with this idea, longstanding evidence demonstrates that invasive brain injuries that disrupt tissue compartmentalization enable adult cortical astrocytes, in both mice and humans, to revert to a more plastic state and form multipotent neurospheres in vitro. However, the molecular and cellular mechanisms linking injury, glial reactivity, fate conversion, and permissive dedifferentiation have remained elusive. To address these questions, we first developed reactive cultures (RCs) derived from injured mouse cortex, composed of reactive astrocytes, microglia, infiltrating macrophages, and other brain cell types. We found that these RCs promote neurosphere formation from cocultured non-injured cortical glia. Moreover, we demonstrated that the secretome derived from mouse and human macrophages is sufficient to induce neurosphere formation and strongly enhances astrocyte-to-neuron conversion efficiency, implicating macrophage-secreted molecules as key mediators of these effects. Consistently, pharmacological blockade of macrophage recruitment using a CCR2 inhibitor prevents neurosphere formation from injured brain tissue. Proteomic analysis of conditioned media from macrophages and RCs identified secreted proteins that activate integrin pathways, including Galectin-3, Spp1, GPNMB, and Sparc. Exposure of uninjured cortical tissue to any of these proteins alone was sufficient to induce neurosphere formation, an effect that was blocked by the integrin antagonist CWHM-12. Together, these findings demonstrate that infiltrating immune cells drive lineage plasticity in the injured brain through integrin-activating soluble factors, providing new mechanistic insights with promising implications for neuronal regenerative strategies.