Circular RNA expression profile in blood according to ischemic stroke etiology

Background: The discovery of novel biomarkers of stroke etiology would be most helpful in management of acute ischemic stroke patients. Recently, circular RNAs (circRNAs) have been proposed as candidate biomarkers of neurological conditions due to its high stability. circRNAs function as sponges, sequestering miRNAs and are involved in most relevant biological functions. Our aim was to identify differentially expressed circRNAs in acute ischemic stroke patients according to stroke etiology. Methods: A comprehensive expression profile of blood circRNAs was conducted by Arraystar Human circRNA arrays (13,617 probes) on a discovery cohort of 30 stroke patients with different stroke etiologies by TOAST classification. Real-time quantitative PCR (RT-qPCR) was used to validate array results in a cohort of 50 stroke patients. Functional in silico analysis was performed to identify potential interactions with microRNAs (miRNAs) and pathways underlying deregulated circRNAs. Results: A set of 60 circRNAs were found to be upregulated in atherotrombotic versus cardioembolic strokes (fold-change > = 1.5 and p-value ≤ 0.05). Differential expression of hsa_circRNA_102488, originated from UBA52 gene, was replicated in the validation cohort. RNA-binding proteins (RBPs) sites of hsa_circRNA_102488 clustered around AGO2 and FUS proteins. Further functional analysis revealed interactions between deregulated circRNAs and a set of miRNAs involved in stroke-related pathways, such as fatty acid biogenesis or lysine degradation. Conclusion: Different stroke subtypes show specific profiles of circRNAs expression. circRNAs may serve as a new source of biomarkers of stroke etiology in acute ischemic stroke patients.This work was supported by Navarre Government Funding (Industry and Health department) through ADITECH and by RED INVICTUS (RD16/0019/0024) from the Institute of Health Carlos III, jointly funded by European Regional Development Fund (ERDF), European Union. AUC received a grant 'Doctorados industriales 2018–2020' founded by Government of Navarra and MM received a grant 'Programa de intensificación' founded by 'LaCaixa Foundation' and Fundación Caja-Navarra

Serum Fatty Acids and Risk of Ischemic Stroke in Postmenopausal Women

Ischemic stroke is a major cause of death and disability among postmenopausal women. One of the risk factors of ischemic stroke is diet, including dietary fat intake. It has been established that intake of trans and saturated fatty acids are positively associated with coronary heart disease, whereas monounsaturated and polyunsaturated fatty acids are inversely associated. Despite the expectation that these associations would be consistent for ischemic stroke, this has not been the case in studies using participant reported measures of fatty acid intake. Rather, studies using biomarkers of fatty acid intake, such as serum, have had more success in finding the expected associations. This dissertation attempts to explain these inconsistent results through two aims. The first aim was to estimate the correlations between individual serum fatty acids and fatty acid intakes, which may partially explain previous inconsistent results from studies using different fatty acid assessment methods. The participants were 925 women from the Women's Health Initiative Observational Study (WHI-OS) of postmenopausal US women. Serum fatty acid composition was determined from a fasting serum sample collected at enrollment. Fatty acid intakes were measured using a 122-item food frequency questionnaire also at enrollment. Individual fatty acids with the highest Spearman rank correlations between serum and dietary intake were docosapentaenoic (DHA), eicosapentaenoic (EPA), and 18:1t fatty acid. Serum saturated, monounsaturated, and n6 polyunsaturated fatty acids were not correlated with the corresponding intake measures. This work highlights the need for further research to find suitable biomarkers for intakes of individual fatty acids. The second aim was to estimate the association between individual serum fatty acids and incidence of ischemic stroke and ischemic stroke subtypes. We conducted a case-control study nested in the WHI-OS. Incident ischemic stroke cases were centrally adjudicated, classified by etiologic subtype, and matched (1:1) to controls for a total of 964 case-control pairs. Serum linelaidic, palmitic, and oleic acids were associated with higher incidence of ischemic stroke, while serum EPA, docosapentaenoic (DPA), DHA, and arachidonic acids were associated with lower incidence. These associations were generally consistent for atherothrombotic and lacunar, but not cardioembolic, stroke. This work highlights the importance of individual fatty acids in the development of particular subtypes of ischemic stroke. This dissertation brings to attention the areas for future research. First, there is a need to find suitable biomarkers for individual fatty acid intakes. Second, future studies should explore the associations between individual fatty acids and disease, not only focusing on fatty acid groups. Third, the heterogeneous etiology of ischemic stroke suggests that ischemic stroke subtypes should be examined separately. Lastly, public health initiatives to increase the intake of DHA and EPA and reduce intake of 18:1t may reduce the incidence of ischemic stroke among postmenopausal US women.Doctor of Philosoph

Progress and potential roles blood biomarkers of ischemic stroke in clinical setting

Stroke is one of the leading causes of death and disability which involving a complex pathophysiology with multiple mechanisms. Rapid treatment is necessary to terminate the disease progression, hence minimizing CNS damage and subsequent disability. Stroke diagnostic process composed of history taking, neurological examination and supplemented with neuroimaging. Imaging modalities such as CT-scan or MRI are essential in establishing a definitive diagnosis of ischemic stroke. However, the high cost and limited number made them inaccessible for those who have low or middle income which will delay the diagnosis and treatment. On the other hand, blood biomarker has potential in either diagnostic or prognostic aspect of ischaemic stroke management. It has a promising potential to aid diagnosis, determine the subtype of stroke, predicting the outcome or early neurological deterioration, and recurrence. It also could potentially help to assess the risk of hemorrhagic transformation, treatment selection, as well as to detect salvageable ischemic penumbra. Although it could not replace neuroimaging, blood-based biomarker assessment had lower cost and faster result. However, despite its promising potential, none of the blood biomarkers is currently used in clinical practice. Therefore, further studies are needed to develop biomarkers or panels of biomarkers with better sensitivity and specificity. This review provides a highlight and summary of blood biomarkers based on their potential application in a clinical setting.</p

At the Intersection of Gut Microbiome and Stroke: A Systematic Review of the Literature

Background: Ischemic and hemorrhagic stroke are associated with a high rate of long-term disability and death. Recent investigations focus efforts to better understand how alterations in gut microbiota composition influence clinical outcomes. A key metabolite, trimethylamine N-oxide (TMAO), is linked to multiple inflammatory, vascular, and oxidative pathways. The current biochemical underpinnings of microbial effects on stroke remain largely understudied. The goal of our study is to explore the current literature to explain the interactions between the human gut microbiome and stroke progression, recovery, and outcome. We also provide a descriptive review of TMAO. Methods: A systematic literature search of published articles between January 1, 1990, and March 22, 2020, was performed on the PubMed database to identify studies addressing the role of the microbiome and TMAO in the pathogenesis and recovery of acute stroke. Our initial investigation focused on human subject studies and was further expanded to include animal studies. Relevant articles were included, regardless of study design. The analysis included reviewers classifying and presenting selected articles by study design and sample size in a chart format. Results: A total of 222 titles and abstracts were screened. A review of the 68 original human subject articles resulted in the inclusion of 24 studies in this review. To provide further insight into TMAO as a key player, an additional 40 articles were also reviewed and included. Our findings highlighted that alterations in richness and abundance of gut microbes and increased plasma TMAO play an important role in vascular events and outcomes. Our analysis revealed that restoration of a healthy gut, through targeted TMAO-reducing therapies, could provide alternative secondary prevention for at-risk patients. Discussion: Biochemical interactions between the gut microbiome and inflammation, resulting in metabolic derangements, can affect stroke progression and outcomes. Clinical evidence supports the importance of TMAO in modulating underlying stroke risk factors. Lack of standardization and distinct differences in sample sizes among studies are major limitations

Hemorrhagic transformation of ischemic stroke

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DECODING THE TRANSCRIPTOME: GENE EXPRESSION PROFILES IN ACUTE ISCHEMIC STROKE PATIENTS

Introduction: Acute ischemic stroke (AIS) is a complex vascular disorder characterized by sudden focal neurological symptoms lasting at least 24 hours, representing a significant source of long-term disability in Western populations. The urgent restoration of cerebral blood flow is typically achieved through a combination of intravenous rt-PA treatment and mechanical thrombectomy (MT), offering access to cerebral thrombi (CT) for investigation. Recent advancements in omics technologies have enabled comprehensive investigations into clot composition and stroke mechanisms, enhancing predictive capabilities. AIS is classified into five subtypes based on the TOAST classification system: cardioembolic (CE), large-vessel atherosclerotic (LAA), lacunar (SVO), cryptogenic, and other causes. Determining the etiologic classification is essential for establishing prognosis, outcome, and event management factors, thus enabling the development of personalized medicine in which prevention and treatment strategies are increasingly individualized. Aim: The primary thrust of this investigation is to delve into the intricate genetic landscape of ischemic stroke through the application of cutting-edge transcriptomic approaches. Our specific focus centers on the meticulous exploration of molecular signatures within thrombotic tissue and peripheral venous blood (PB) that are uniquely associated with distinct stroke subtypes. Through this systematic inquiry, we aim to unveil the intricate interplay between gene expression patterns and the nuanced phenotypic differences that characterize the spectrum of ischemic stroke subtypes. Methods: We conducted gene expression profiling on a cohort of 92 AIS patients. CT samples obtained during MT were preserved in RNA later, while PB in tubes containing a reagent that protects RNA from degradation and minimizes ex vivo changes in gene expression. RNA extraction was performed using the PAX gene blood miRNA kit, and global gene expression profiling was accomplished using Affymetrix technology with the GeneChip Human Transcriptome Array 2.0 platform, allowing the analysis of 44,699 genes, &gt;285,000 full-length transcripts coverage, combined with Affymetrix Transcriptome Analysis Console (TAC) Software, followed by a Gene Ontology (GO) and Reactome enrichment analysis to identify biological processes and pathways affected by different stroke etiologies. Results: The initial observation from our analysis, reinforced by the Cibersort analysis, spotlights a robust activation of the immune response in the aftermath of the ischemic event. The results of the analysis reveal consistency and uniformity in the quantity of different types of immune cells present in the samples, suggesting a similar immune cell composition in both CT and PB. Specifically, a predominance of neutrophils, the type of white blood cell that plays a crucial role in the body's immune response, emerged in both types of analyzed material, constituting 33% and 66% of the total, respectively. Analysis of CT data unveiled significant differences (p-value&lt;0.05 and FoldChange=2 as threshold) in gene expression profiles when comparing strokes of LAA origin with CE and cryptogenic strokes. Notably, LAA strokes exhibited overexpression of 301 genes compared to CE strokes, with differential expression of 209 genes compared to cryptogenic strokes. The next step was to conduct a GO and REACTOME enrichment analysis, so as to identify, respectively, the biological processes and pathways that are impacted by the condition being examined. Among them, biological processes such as neutrophil degranulation, regulation of cytokine production, and processes involved in damage response appear to be significantly enriched. Specifically, genes such as S100A12 (logFC=3.826 p-val.adj=0,002519), S100A9 (logFC=2.8555 p-val.adj= 0,000748), and S100A8 (logFC=3.175 p-val.adj= 0,001599), associated with inflammation and atherosclerotic plaque instability, were prominently overexpressed in LAA strokes. Additionally, genes involved in inflammation, including MMP9 (logFC=2.3845 p-val.adj= 0,002712), IL-1β (logFC=2.1035 p-val.adj= 0,004624), and VNN2 (logFC=5.1645 p-val.adj= 0,002925), showed significant upregulation. In the realm of microRNAs (miRNAs), we highlighted the substantial overexpression of miRNA-223 (logFC=3.093 p-val.adj= 0,001225) in atherosclerotic-origin strokes. This particular miRNA has a significant role in inflammatory processes and has been linked, based on existing literature, to cardiovascular diseases. Despite thorough exploration, no significant differences in gene expression were detected in comparisons beyond other subtypes in CT and PB samples. This underscores a unique molecular landscape within the identified subtypes, emphasizing the necessity for a nuanced understanding of the underlying biology. Conclusions: Transcriptome profiling has provided valuable insights into the molecular landscape of AIS. The overexpression of genes such as MMP-9, S100A12, S100A9 and S100A8 in atherosclerotic strokes underscores their association with plaque instability and adverse neurological outcomes. Dysregulation of genes such as IL-1β exacerbates ischemic injury, highlighting their crucial role in AIS pathophysiology. Transcriptome signatures hold promise in distinguishing between stroke etiologies, paving the way for personalized approaches to secondary stroke prevention