Altered Extracellular Vesicle MicroRNA Expression in Ischemic Stroke and Small Vessel Disease

Machine Learning-Based Etiologic Subtyping of Ischemic Stroke Using Circulating Exosomal microRNAs

Ischemic stroke is a major cause of mortality worldwide. Proper etiological subtyping of ischemic stroke is crucial for tailoring treatment strategies. This study explored the utility of circulating microRNAs encapsulated in extracellular vesicles (EV-miRNAs) to distinguish the following ischemic stroke subtypes: large artery atherosclerosis (LAA), cardioembolic stroke (CES), and small artery occlusion (SAO). Using next-generation sequencing (NGS) and machine-learning techniques, we identified differentially expressed miRNAs (DEMs) associated with each subtype. Through patient selection and diagnostic evaluation, a cohort of 70 patients with acute ischemic stroke was classified: 24 in the LAA group, 24 in the SAO group, and 22 in the CES group. Our findings revealed distinct EV-miRNA profiles among the groups, suggesting their potential as diagnostic markers. Machine-learning models, particularly logistic regression models, exhibited a high diagnostic accuracy of 92% for subtype discrimination. The collective influence of multiple miRNAs was more crucial than that of individual miRNAs. Additionally, bioinformatics analyses have elucidated the functional implications of DEMs in stroke pathophysiology, offering insights into the underlying mechanisms. Despite limitations like sample size constraints and retrospective design, our study underscores the promise of EV-miRNAs coupled with machine learning for ischemic stroke subtype classification. Further investigations are warranted to validate the clinical utility of the identified EV-miRNA biomarkers in stroke patients.

Small RNA signatures of acute ischemic stroke in L1CAM positive extracellular vesicles

L1CAM-positive extracellular vesicles (L1EV) are an emerging biomarker that may better reflect ongoing neuronal damage than other blood-based biomarkers. The physiological roles and regulation of L1EVs and their small RNA cargoes following stroke is unknown. We sought to characterize L1EV small RNAs following stroke and assess L1EV RNA signatures for diagnosing stroke using weighted gene co-expression network analysis and random forest (RF) machine learning algorithms. Interestingly, small RNA sequencing of plasma L1EVs from patients with stroke and control patients (n = 28) identified micro(mi)RNAs known to be enriched in the brain. Weighted gene co-expression network analysis (WGCNA) revealed small RNA transcript modules correlated to diagnosis, initial NIH stroke scale, and age. L1EV RNA signatures associated with the diagnosis of AIS were derived from WGCNA and RF classification. These small RNA signatures demonstrated a high degree of accuracy in the diagnosis of AIS with an area under the curve (AUC) of the signatures ranging from 0.833 to 0.932. Further work is necessary to understand the role of small RNA L1EV cargoes in the response to brain injury, however, this study supports the utility of L1EV small RNA signatures as a biomarker of stroke.

Exploring vascular contributions to cognitive impairment and dementia (ENIGMA): protocol for a prospective observational study

BACKGROUND

Post-stroke cognitive impairment (PSCI) is common. However, the underlying pathophysiology remains largely unknown. Understanding the role of microvascular changes and finding markers that can predict PSCI, could be a first step towards better screening and management of PSCI. Capillary dysfunction is a pathological feature of cerebral small vessel disease and may play a role in the mechanisms underlying PSCI. Extracellular vesicles (EVs) are secreted from cells and may act as disease biomarkers. We aim to investigate the role of capillary dysfunction in PSCI and the associations between EV characteristics and cognitive function one year after acute ischemic stroke (AIS) and transient ischemic attack (TIA).

METHODS

The ENIGMA study is a single-centre prospective clinical observational study conducted at Aarhus University Hospital, Denmark. Consecutive patients with AIS and TIA are included and followed for one year with follow-up visits at three and 12 months. An MRI is performed at 24 h and 12 months follow-up. EV characteristics will be characterised from blood samples drawn at 24 h and three months follow-up. Cognitive function is assessed three and 12 months after AIS and TIA using the Repeatable Battery for the Assessment of Neuropsychological Status.

DISCUSSION

Using novel imaging and molecular biological techniques the ENIGMA study will provide new knowledge about the vascular contributions to cognitive decline and dementia.

TRIAL REGISTRATION

The study is retrospectively registered as an ongoing observational study at ClinicalTrials.gov with the identifier NCT06257823.

Blood-based biomarkers of cerebral small vessel disease

Age-associated cerebral small vessel disease (CSVD) represents a clinically heterogenous condition, arising from diverse microvascular mechanisms. These lead to chronic cerebrovascular dysfunction and carry a substantial risk of subsequent stroke and vascular cognitive impairment in aging populations. Owing to advances in neuroimaging, in vivo visualization of cerebral vasculature abnormities and detection of CSVD, including lacunes, microinfarcts, microbleeds and white matter lesions, is now possible, but remains a resource-, skills- and time-intensive approach. As a result, there has been a recent proliferation of blood-based biomarker studies for CSVD aimed at developing accessible screening tools for early detection and risk stratification. However, a good understanding of the pathophysiological processes underpinning CSVD is needed to identify and assess clinically useful biomarkers. Here, we provide an overview of processes associated with CSVD pathogenesis, including endothelial injury and dysfunction, neuroinflammation, oxidative stress, perivascular neuronal damage as well as cardiovascular dysfunction. Then, we review clinical studies of the key biomolecules involved in the aforementioned processes. Lastly, we outline future trends and directions for CSVD biomarker discovery and clinical validation.

Considering Context-Specific microRNAs in Ischemic Stroke with Three "W": Where, When, and What

MicroRNAs are short non-coding RNA molecules that function as critical regulators of various biological processes through negative regulation of gene expression post-transcriptionally. Recent studies have indicated that microRNAs are potential biomarkers for ischemic stroke. In this review, we first illustrate the pathogenesis of ischemic stroke and demonstrate the biogenesis and transportation of microRNAs from cells. We then discuss several promising microRNA biomarkers in ischemic stroke in a context-specific manner from three dimensions: biofluids selection for microRNA extraction (Where), the timing of sample collection after ischemic stroke onset (When), and the clinical application of the differential-expressed microRNAs during stroke pathophysiology (What). We show that microRNAs have the utilities in ischemic stroke diagnosis, risk stratification, subtype classification, prognosis prediction, and treatment response monitoring. However, there are also obstacles in microRNA biomarker research, and this review will discuss the possible ways to improve microRNA biomarkers. Overall, microRNAs have the potential to assist clinical treatment, and developing microRNA panels for clinical application is worthwhile.

Exosomal miRNAs as Biomarkers of Ischemic Stroke

Exosomes are small lipid bilayer membrane particles released from all living cells into the extracellular environment. They carry several molecules and have a critical role in cell-cell communication under physiological and pathological conditions. In recent decades, exosomes, and especially their cargo, have emerged as a promising tool for several clinical conditions. However, the literature has become increasingly unambiguous in defining the role of exosomes in chronic cerebrovascular diseases. Because they can pass through the blood-brain barrier, they have great potential to reflect intracerebral changes. They can, thus, provide valuable insight into the mechanisms of central nervous system diseases. The purpose of this review is to describe the literature on the role of exosomal miRNA, which represents the most widely investigated exosomal biomarker, in strokes. First, we provide an overview of exosomes, from biology to isolation and characterization. Then, we describe the relationship between exosomes and stroke pathogenesis. Finally, we summarize the human studies evaluating exosomal miRNA biomarkers of stroke. Although the collective literature supports the potential use of exosomal miRNA as biomarkers of ischemic stroke, there are still several limitations hampering their introduction into clinical practice.

Extracellular vesicles and their microRNA cargo in ischaemic stroke

Acute ischaemic stroke (AIS) is a leading cause of death and disability. MicroRNAs (miRNAs) are short non-coding RNAs which hold the potential to act as a novel biomarker in AIS. The majority of circulating miRNAs are actively encapsulated by extracellular vesicles (EVs) produced by many cells and organs endogenously. EVs released by mesenchymal stem cells (MSCs) have been extensively studied for their therapeutic potential. In health and disease, EVs are vital for intercellular communication, as the cargo within EVs can be exchanged between neighbouring cells or transported to distant sites. It is clear here from both current preclinical and clinical studies that AIS is associated with specific EV-derived miRNAs, including those transported via MSC-derived EVs. In addition, current studies provide evidence to show that modulating levels of specific EV-derived miRNAs in AIS provides a novel therapeutic potential of miRNAs in the treatment of stroke. Commonalities exist in altered miRNAs across preclinical and clinical studies. Of those EV-packaged miRNAs, miRNA-124 was described both as an EV-packaged biomarker and as a potential EV-loaded therapeutic in experimental models. Alterations of miRNA-17 family and miRNA-17-92 cluster were identified in preclinical, clinical and MSC-EV-mediated neuroprotection in experimental stroke. Finally, miRNA-30d and -30a were found to mediate therapeutic effect when overexpressed from MSC and implicated as a biomarker clinically. Combined, EV-derived miRNAs will further our understanding of the neuropathological processes triggered by AIS. In addition, this work will help determine the true clinical value of circulating EV-packaged miRNAs as biomarkers of AIS or as novel therapeutics in this setting.

Exosomal miR-320e as a Novel Potential Biomarker for Cerebral Small Vessel Disease

Background

Cerebral small vessel disease (CSVD) with an insidious onset can cause overall neurological dysfunction and dementia, bringing a massive burden to society. However, the pathogenesis of CSVD is complex and reliable non-invasive biomarkers for diagnosis are still not available at present. Our study aimed to investigate abnormal exosomal miRNA patterns via microarray analysis and identify candidate biomarkers for CSVD.

Methods

We isolated exosomes from the plasma of all subjects and identified exosomes via currently universally accepted methods. The miRNAs were profiled through microarrays, and then the expression of selected differentially expressed miRNAs was validated through RT-PCR. GO and KEGG analysis predicted possible functions of differentially expressed miRNAs. Receiver operating characteristic (ROC) curve was employed to observe the diagnostic value of selective miRNAs. Finally, the relationship between the expression of miR-320e and the CSVD burden was analyzed.

Results

A total of 14 miRNAs displayed differential enrichment levels with |fold change|≥1.5 and p<0.05 through miRNA microarray analysis. The RT-PCR analysis validated that exosomal miR-320e was significantly downregulated in CSVD patients (p<0.0001). ROC curve analysis of exosomal miR-320e showed the area under the curve of 0.752. According to the multivariable analysis, miR-320e was an independent predictor of white matter hyperintensity ([aOR]= 0.452, 95% confidence interval [CI]= 0.258-0.792, p=0.006) and exhibited a negative correlation with the load of periventricular white matter hyperintensities (p=0.0021) and deep white matter hyperintensities (p=0.0018), respectively. In addition, it exhibited a negative correlation with total CSVD burden score (r=-0.276, p=0.001).

Conclusion

In our study, plasma exosomal miR-320e has a certain diagnostic value for CSVD, and a significant correlation with imaging burden of CSVD. Overall, exosomal miR-320e has the potential to be a novel biomarker for CSVD, but further research with a large sample size is necessary to assess its clinical utility.

Extracellular Vesicles and Ischemic Cardiovascular Diseases

Characterized by coronary artery obstruction or stenosis, ischemic cardiovascular diseases as advanced stages of coronary heart diseases commonly lead to left ventricular aneurysm, ventricular septal defect, and mitral insufficiency. Extracellular vesicles (EVs) secreted by diverse cells in the body exert roles in cell-cell interactions and intrinsic cellular regulations. With a lipid double-layer membrane and biological components such as DNA, protein, mRNA, microRNAs (miRNA), and siRNA inside, the EVs function as paracrine signaling for the pathophysiology of ischemic cardiovascular diseases and maintenance of the cardiac homeostasis. Unlike stem cell transplantation with the potential tumorigenicity and immunogenicity, the EV-based therapeutic strategy is proposed to satisfy the demand for cardiac repair and regeneration while the circulating EVs detected by a noninvasive approach can act as precious biomarkers. In this chapter, we extensively summarize the cardioprotective functions of native EVs and bioengineered EVs released from stem cells, cardiomyocytes, cardiac progenitor cells (CPCs), endothelial cells, fibroblast, smooth muscle cells, and immune cells. In addition, the potential of EVs as robust molecule biomarkers is discussed for clinical diagnosis of ischemic cardiovascular disease, attributed to the same pathology of EVs as that of their origin. Finally, we highlight EV-based therapy as a biocompatible alternative to direct cell-based therapy for ischemic cardiovascular diseases.

H2S-mediated inhibition of RhoA/ROCK pathway and noncoding RNAs in ischemic stroke

Ischemic stroke is one of major causes of disability. In the pathological process of ischemic stroke, the up-regulation of Ras homolog gene family, member A (RhoA) and its downstream effector, Ras homolog gene family (Rho)-associated coiled coil-containing kinase (ROCK), contribute to the neuroinflammation, blood-brain barrier (BBB) dysfunction, neuronal apoptosis, axon growth inhibition and astrogliosis. Accumulating evidences have revealed that hydrogen sulphide (H₂S) could reduce brain injury in animal model of ischemic stroke via inhibiting the RhoA/ROCK pathway. Recently, noncoding RNAs (ncRNAs) such as circular RNAs (circRNAs), long noncoding RNAs (lncRNAs) and microRNAs (miRNAs) have attracted much attention because of their essential role in adjusting gene expression both in physiological and pathological conditions. Numerous studies have uncovered the role of RhoA/ROCK pathway and ncRNAs in ischemic stroke. In this review, we focused on the role of H₂S, RhoA/ROCK pathway and ncRNAs in ischemic stroke and aimed to reveal new strategies for preventing and treating this devastating disease.

Role of Circulating Exosomes in Cerebrovascular Diseases: A Comprehensive Review

Exosomes are lipid bilayer vesicles that contain multiple macromolecules secreted by the parent cells and play a vital role in intercellular communication. In recent years, the function of exosomes in cerebrovascular diseases (CVDs) has been intensively studied. Herein, we briefly review the current understanding of exosomes in CVDs. We discuss their role in the pathophysiology of the diseases and the value of the exosomes for clinical applications as biomarkers and potential therapies.

Systematic review: Association between circulating microRNA expression & stroke

This systematic review aimed to establish the range and quality of clinical and preclinical evidence supporting the association of individual microRNAs, and the use of microRNA expression in the diagnosis and prognosis of ischaemic or haemorrhagic stroke. Electronic databases were searched from 1993 to October 2021, using key words relevant to concepts of stroke and microRNA. Studies that met specific inclusion and exclusion criteria were selected for data extraction. To minimise erroneous associations, findings were restricted to microRNAs reported to change in more than two independent studies. Of the papers assessed, 155 papers reported a change in microRNA expression observed in more than two independent studies. In ischaemic studies, two microRNAs were consistently differentially expressed in clinical samples (miR-29b & miR-146a) and four were altered in preclinical samples (miR-137, miR-146a, miR-181b & miR-223-3p). Across clinical and preclinical haemorrhagic studies, four microRNAs were downregulated consistently (miR-26a, miR-126, miR-146a & miR-155). Across included studies, miR-126 and miR-146a were the only two microRNAs to be differentially expressed in clinical and preclinical cohorts following ischaemic or haemorrhagic stroke. Further studies, employing larger populations with consistent methodologies, are required to validate the true clinical value of circulating microRNAs as biomarkers of ischaemic and haemorrhagic stroke.

Acute Cerebral Ischemia Increases a Set of Brain-Specific miRNAs in Serum Small Extracellular Vesicles

Small extracellular vesicles (sEVs) miRNAs are promising diagnosis and prognosis biomarkers for ischemic stroke (IS). This study aimed to determine the impact of IS on the serum sEVs miRNA profile of IS patients and a transient middle cerebral artery occlusion (tMCAO) mouse model. Small RNAseq was used to define the serum sEVs miRNA profile in IS patients and healthy controls (HC), and tMCAO mice and sham controls. Among the 1,444 and 1,373 miRNAs identified in human and mouse serum sEVs, the expression of 424 and 37 miRNAs was significantly altered in the IS patients and tMCAO mice, respectively (| Log2FC| ≥ 1, p &lt; 0.01). Notably, five of the top 25 upregulated miRNAs in IS patients were brain-specific or enriched, including hsa-miR-9-3p, hsa-miR-124-3p, hsa-miR-143-3p, hsa-miR-98-5p, and hsa-miR-93-5p. Upregulation of these four miRNAs was further validated by qPCR. Nine of the 20 upregulated miRNAs in tMCAO mice were also brain-specific or enriched miRNAs. Temporal analysis indicated that the dynamics of mmu-miR-9-5p, mmu-miR-124-3p, mmu-miR-129-5p, and mmu-miR-433-3p were closely correlated with the evolution of ischemic brain injury, as their expression increased at 0.5 days after the onset of ischemia, peaked at day 1 or 3, and returned to normal levels at day 7 and 14. Notably, with the exceptions of mmu-miR-128-3p, the expression of the other eight miRNAs in the mouse serum sEVs was unaffected in the lipopolysaccharide (LPS)-induced neuroinflammation model. Together, in this study, we provided a comprehensive view of the influences of IS on the serum sEVs miRNA profile of IS patients and tMCAO mice and demonstrated the increment of a set of brain-specific miRNAs in serum sEVs after acute cerebral ischemia, which could be promising candidates directly reflecting the ischemic brain injury.

ER Stress is Involved in Mast Cells Degranulation via IRE1α/miR-125/Lyn Pathway in an Experimental Intracerebral Hemorrhage Mouse Model

The degranulation of mast cells accounts for the development of neuroinflammation following intracerebral hemorrhage (ICH). Inhibition of IRE1α, a sensor signaling protein related to endoplasmic reticulum stress, has been shown to exert anti-inflammatory effects in several neurological diseases. The objective of this study was to investigate the effects of IRE1α inhibition on mast cells degranulation in an ICH mouse model and to explore the contribution of miR-125/Lyn pathway in IRE1α-mediated mast cells degranulation. Male mice were subjected to ICH by intraparenchymal injection of autologous blood. STF083010, an inhibitor of IRE1α, was administered intranasally at 1 h after ICH induction. AntimiR-125 was delivered by intracerebroventricular (i.c.v.) injection prior to ICH induction to elucidate the possible mechanisms. Western blot analysis, immunofluorescence staining, neurological test, hematoma volume, brain water content, toluidine blue staining and reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR) were performed. Endogenous phosphorylated IRE1α (p-IRE1α), tryptase, interleukin-17A (IL-17A), tumor necrosis factor α (TNF-α) and tryptase mRNA were increased in time dependent manner while miR-125b-2-3p was decreased after ICH. Inhibition of IRE1α, with STF083010, remarkably reduced brain water content, improved neurological function, decreased hematoma volume, upregulated the expression of miR-125b-2-3p, decreased the number of mast cells, and downregulated the protein expression of Lyn kinase, XBP1s (spliced X-box binding protein-1), tryptase, IL-17A and TNF-α. The downregulation of Lyn kinase, tryptase, IL-17A, TNF-α, and decreased mast cells number were reversed by antimiR-125. The present findings demonstrate that IRE1α inhibition attenuates mast cells degranulation and neuroinflammation, at least partially, through IRE1α/miR-125/Lyn signaling pathway after ICH.

microRNA-455-5p alleviates neuroinflammation in cerebral ischemia/reperfusion injury

Neuroinflammation is a major pathophysiological factor that results in the development of brain injury after cerebral ischemia/reperfusion. Downregulation of microRNA (miR)-455-5p after ischemic stroke has been considered a potential biomarker and therapeutic target for neuronal injury after ischemia. However, the role of miR-455-5p in the post-ischemia/reperfusion inflammatory response and the underlying mechanism have not been evaluated. In this study, mouse models of cerebral ischemia/reperfusion injury were established by transient occlusion of the middle cerebral artery for 1 hour followed by reperfusion. Agomir-455-5p, antagomir-455-5p, and their negative controls were injected intracerebroventricularly 2 hours before or 0 and 1 hour after middle cerebral artery occlusion (MCAO). The results showed that cerebral ischemia/reperfusion decreased miR-455-5p expression in the brain tissue and the peripheral blood. Agomir-455-5p pretreatment increased miR-455-5p expression in the brain tissue, reduced the cerebral infarct volume, and improved neurological function. Furthermore, primary cultured microglia were exposed to oxygen-glucose deprivation for 3 hours followed by 21 hours of reoxygenation to mimic cerebral ischemia/reperfusion. miR-455-5p reduced C-C chemokine receptor type 5 mRNA and protein levels, inhibited microglia activation, and reduced the production of the inflammatory factors tumor necrosis factor-α and interleukin-1β. These results suggest that miR-455-5p is a potential biomarker and therapeutic target for the treatment of cerebral ischemia/reperfusion injury and that it alleviates cerebral ischemia/reperfusion injury by inhibiting C-C chemokine receptor type 5 expression and reducing the neuroinflammatory response.

Potential Role of Exosomes in Ischemic Stroke Treatment

Ischemic stroke is a life-threatening cerebral vascular disease and accounts for high disability and mortality worldwide. Currently, no efficient therapeutic strategies are available for promoting neurological recovery in clinical practice, except rehabilitation. The majority of neuroprotective drugs showed positive impact in pre-clinical studies but failed in clinical trials. Therefore, there is an urgent demand for new promising therapeutic approaches for ischemic stroke treatment. Emerging evidence suggests that exosomes mediate communication between cells in both physiological and pathological conditions. Exosomes have received extensive attention for therapy following a stroke, because of their unique characteristics, such as the ability to cross the blood brain–barrier, low immunogenicity, and low toxicity. An increasing number of studies have demonstrated positively neurorestorative effects of exosome-based therapy, which are largely mediated by the microRNA cargo. Herein, we review the current knowledge of exosomes, the relationships between exosomes and stroke, and the therapeutic effects of exosome-based treatments in neurovascular remodeling processes after stroke. Exosomes provide a viable and prospective treatment strategy for ischemic stroke patients.

Emerging Impact of Non-coding RNAs in the Pathology of Stroke

Ischemic stroke (IS) is an acute cerebral vascular event with high mortality and morbidity. Though the precise pathophysiologic routes leading to this condition are not entirely clarified, growing evidence from animal and human experiments has exhibited the impact of non-coding RNAs in the pathogenesis of IS. Various lncRNAs namely MALAT1, linc-SLC22A2, linc-OBP2B-1, linc_luo_1172, linc-DHFRL1-4, SNHG15, linc-FAM98A-3, H19, MEG3, ANRIL, MIAT, and GAS5 are possibly involved in the pathogenesis of IS. Meanwhile, lots of miRNAs contribute in this process. Differential expression of lncRNAs and miRNAs in the sera of IS patients versus unaffected individuals has endowed these transcripts the aptitude to distinguish at risk patients. Despite conduction of comprehensive assays for evaluation of the influence of lncRNAs/miRNAs in the pathogenesis of IS, therapeutic impacts of these transcripts in IS have not been clarified. In the present paper, we review the impact of lncRNAs/miRNAs in the pathobiology of IS through assessment of evidence provided by human and animal studies.

Circulating Extracellular Vesicle Proteins and MicroRNA Profiles in Subcortical and Cortical-Subcortical Ischaemic Stroke

In order to investigate the role of circulating extracellular vesicles (EVs), proteins, and microRNAs as damage and repair markers in ischaemic stroke depending on its topography, subcortical (SC), and cortical-subcortical (CSC) involvement, we quantified the total amount of EVs using an enzyme-linked immunosorbent assay technique and analysed their global protein content using proteomics. We also employed a polymerase chain reaction to evaluate the circulating microRNA profile. The study included 81 patients with ischaemic stroke (26 SC and 55 CSC) and 22 healthy controls (HCs). No differences were found in circulating EV levels between the SC, CSC, and HC groups. We detected the specific expression of C1QA and Casp14 in the EVs of patients with CSC ischaemic stroke and the specific expression of ANXA2 in the EVs of patients with SC involvement. Patients with CSC ischaemic stroke showed a lower expression of miR-15a, miR-424, miR-100, and miR-339 compared with those with SC ischaemic stroke, and the levels of miR-339, miR-100, miR-199a, miR-369a, miR-424, and miR-15a were lower than those of the HCs. Circulating EV proteins and microRNAs from patients with CSC ischaemic stroke could be considered markers of neurite outgrowth, neurogenesis, inflammation process, and atherosclerosis. On the other hand, EV proteins and microRNAs from patients with SC ischaemic stroke might be markers of an anti-inflammatory process and blood–brain barrier disruption reduction.

MicroRNA-17-5p restrains the dysfunction of Ang-II induced podocytes by suppressing secreted modular calcium-binding protein 2 via NF-κB and TGFβ signaling

Glomerulonephritis, also known as nephritis syndrome (nephritis for short), is a common kidney disease. Previous research has proved that microRNAs (miRNAs) frequently regulate various diseases including nephritis. Nonetheless, the biological function and molecular mechanism of miR-17-5p are unclear in nephritis. In the current study, RT-qPCR analysis showed that miR-17-5p was downregulated in Ang II-induced podocytes. Also, according to the results from RT-qPCR analysis, CCK-8 assay, flow cytometric analysis, western blot analysis, and ELISA miR-17-5p elevation alleviated Ang II-induced podocyte injury. Besides, luciferase reporter assay, western blot and RT-qPCR analyses revealed that SMOC2 was targeted by miR-17-5p in Ang II-induced podocytes. Additionally, rescue assays demonstrated that overexpressed SMOC2 counteracted the influence of overexpressed miR-17-5p on cell injury of Ang II-induced podocytes. Moreover, our data suggested that miR-17-5p-SMOC2 axis regulated TGFβ and NF-κB signaling activation in Ang II-induced podocytes. SMOC2 regulated cell viability, apoptosis and extracellular matrix (ECM) deposition in Ang II-induced podocytes via TGFβ signaling, and SMOC2 regulated inflammation in Ang II-induced podocytes through NF-κB signaling. Overall, our study demonstrated that miRNA-17-5p restrained the dysfunction of Ang-II induced podocytes by suppressing SMOC2 via the NF-κB and TGFβ signaling.

Similarities and Differences in Extracellular Vesicle Profiles between Ischaemic Stroke and Myocardial Infarction

Extracellular vesicles (EVs) are involved in intercellular signalling through the transfer of molecules during physiological and pathological conditions, such as ischaemic disease. EVs might therefore play a role in ischaemic stroke (IS) and myocardial infarction (MI). In the present study, we analysed the similarities and differences in the content of circulating EVs in patients with IS and MI. This prospective observational study enrolled 140 participants (81 patients with IS, 37 with MI and 22 healthy controls [HCs]). We analysed the protein and microRNA content from EVs using proteomics and reverse transcription quantitative real-time polymerase chain reaction and compared it between the groups. In the patients with IS and MI, we identified 14 common proteins. When comparing IS and MI, we found differences in the protein profiles (apolipoprotein B, alpha-2-macroglobulin, fibronectin). We also found lower levels of miR-340 and miR-424 and higher levels of miR-29b in the patients with IS and MI compared with the HCs. Lastly, we found higher miR-340 levels in IS than in MI. In conclusion, proteomic and miRNA analyses suggest a relationship between circulating EV content and the patient’s disease state. Although IS and MI affect different organs (brain and heart) with distinct histological characteristics, certain EV proteins and miRNAs appear to participate in both diseases, while others are present only in patients with IS.

Circulating angiopoietin-2 and angiogenic microRNAs associate with cerebral small vessel disease and cognitive decline in older patients reaching end stage renal disease

BACKGROUND

The prevalence of end-stage renal disease (ESRD) is increasing worldwide, with the majority of new ESRD cases diagnosed in patients aged >60 years. These older patients are at increased risk for impaired cognitive functioning, potentially through cerebral small vessel disease (SVD). Novel markers of vascular integrity may be of clinical value for identifying patients at high risk for cognitive impairment.

METHODS

We aimed to associate the levels of Angiopoietin-2 (Ang-2), asymmetric dimethylarginine (ADMA), and a selection of eight circulating angiogenic miRNAs with SVD and cognitive impairment in older patients reaching ESRD that did not initiate renal replacement therapy yet (n = 129; mean age 75.3 years; mean eGFR 16.4 mL/min). We assessed brain MRI changes of SVD (white matter hyperintensity volume, microbleeds and presence of lacunes) and measures of cognition in domains of memory, psychomotor speed and executive function, comprised in a neuropsychological test battery.

RESULTS

Older patients reaching ESRD showed an unfavorable angiogenic profile, as indicated by aberrant levels of Ang-2 and five angiogenic miRNAs (miR-27a, miR-126, miR-132, miR-223, miR-326), compared to healthy persons and patients with diabetic nephropathy. Moreover, Ang-2 associated with SVD and with the domains of psychomotor speed and executive function, while miR-223 and miR-29a associated with memory function.

CONCLUSIONS

Taken together, these novel angiogenic markers might serve to identify older patients with ESRD at risk of cognitive decline, as well as give insight into the underlying (vascular) pathophysiology.

Affinity enrichment of extracellular vesicles from plasma reveals mRNA changes associated with acute ischemic stroke

Currently there is no in vitro diagnostic test for acute ischemic stroke (AIS), yet rapid diagnosis is crucial for effective thrombolytic treatment. We previously demonstrated the utility of CD8(+) T-cells’ mRNA expression for AIS detection; however extracellular vesicles (EVs) were not evaluated as a source of mRNA for AIS testing. We now report a microfluidic device for the rapid and efficient affinity-enrichment of CD8(+) EVs and subsequent EV’s mRNA analysis using droplet digital PCR (ddPCR). The microfluidic device contains a dense array of micropillars modified with anti-CD8α monoclonal antibodies that enriched 158 ± 10 nm sized EVs at 4.3 ± 2.1 × 10⁹ particles/100 µL of plasma. Analysis of mRNA from CD8(+) EVs and their parental T-cells revealed correlation in the expression for AIS-specific genes in both cell lines and healthy donors. In a blinded study, 80% test positivity for AIS patients and controls was revealed with a total analysis time of 3.7 h.

Wijerathne et al develop an approach to quantify mRNA amounts in extracellular vesicles (EVs) from plasma using a microfluidics device to enrich EVs. They show this method allows for the correlation of specific mRNAs with acute ischemic stroke pointing towards potential clinical use.

Circulating miRNA-3552 as a Potential Biomarker for Ischemic Stroke in Rats

Objective

With the growing incidence of ischemic stroke worldwide, there is an urgent need to identify blood biomarkers for ischemic stroke patients. Thus, our aim was to identify potential circulating microRNA (miRNA) as a potential biomarker and to explore its potential mechanism for ischemic stroke in rats.

Methods

The mRNA dataset GSE97537 and miRNA dataset GSE97532 were downloaded from the Gene Expression Omnibus (GEO) GSE97537 including 7 middle cerebral artery occlusion (MCAO) rat brain tissues and 5 sham-operated rat brain tissues GSE97532 including 6 MCAO rat blood samples and 3 sham-operated rat blood samples. Differentially expressed mRNAs and miRNAs with corrected p value ≤ 0.01 and fold change ≥2 or ≤0.05 were identified. To explore potential biological processes and pathways of differentially expressed mRNAs, functional enrichment analysis was performed. The target mRNAs of differentially expressed miRNAs were predicted using DNA Intelligent Analysis (DIANA)-microT tools. The target mRNAs and differentially expressed mRNAs were intersected.

Results

1228 differentially expressed mRNAs in MCAO rat brain tissues were identified. Highly expressed mRNAs were mainly enriched in the inflammatory responses. Nine differentially expressed miRNAs were identified in MCAO rat blood samples. A total of 673 target mRNAs were predicted to significantly bind these differentially expressed miRNAs. Among them, 54 target mRNAs were differentially expressed in MCAO rat blood samples. Enrichment analysis results showed that these 54 target mRNAs were closely related to neurological diseases and immune responses. Among all miRNA-mRNA relationship, miR-3552-CASP3 interaction was identified, indicating that CASP3 might be mediated by miR-3552. Functional enrichment analysis revealed that CASP3 was involved in the apoptosis pathway, indicating that miR-3552 might participate in apoptosis by CASP3.

Conclusion

Our findings reveal that circulating miR-3552 shows promise as a potential biomarker for ischemic stroke in rats.

Extracellular Vesicles in Acute Stroke Diagnostics

There is a large unmet need for fast and reliable diagnostics in several diseases. One such disease is stroke, where the efficacy of modern reperfusion therapies is highly time-dependent. Diagnosis of stroke and treatment initiation should be performed as soon as possible, and preferably before arrival at the stroke center. In recent years, several potential blood biomarkers for stroke have been evaluated, but without success. In this review, we will go into detail on the possibility of utilizing extracellular vesicles (EVs) released into the blood as novel biomarkers for stroke diagnostics. EVs are known to reflect the immediate state of the secreting cells and to be able to cross the blood–brain barrier, thus making them attractive as diagnostic biomarkers of brain diseases. Indeed, several studies have reported EV markers that enable differentiation between stroke patients and controls and, to a lesser extent, the ability to correctly classify the different stroke types. Most of the studies rely on the use of sophisticated and time-consuming methods to quantify specific subpopulations of the nanosized EVs. As these methods cannot be easily implemented in a rapid point of care (POC) test, technical developments followed by prospective clinical studies are needed.

Electro-Acupuncture Promotes the Differentiation of Endogenous Neural Stem Cells via Exosomal microRNA 146b After Ischemic Stroke

Background: Evidences indicate that exosomes-mediated delivery of microRNAs (miRNAs or miRs) is involved in the neurogenesis of stroke. This study was to investigate the role of exosomal miRNAs in non-drug therapy of electro-acupuncture (EA) regulating endogenous neural stem cells for stroke recovery.

Methods: The model of focal cerebral ischemia and reperfusion in rats were established by middle cerebral artery occlusion (MCAO) and treated by EA. The exosomes were extracted from peri-ischemic striatum and identified by exosomal biomarkers, and detected differentially expressed miRNAs with microarray chip. Primary stem cells were cultured, and oxygen–glucose deprivation and reperfusion (OGD/R) was used to mimic vitro ischemic injury.

Results: The levels of exosomal biomarkers TSG101 and CD81 were increased in peri-ischemic striatum after EA treatment, and we revealed 25 differentially expressed miRNAs in isolated exosomes, of which miR-146b was selected for further analysis, and demonstrated that EA increased miR-146b expression and its inhibitors could block the effects. Subsequently, we confirmed that EA upregulated miR-146b expression to promote neural stem cells differentiation into neurons in peri-ischemic striatum. In vitro, it was verified that OGD/R hindered neural stem cells differentiation, and miR-146b inhibitors furtherly suppressed its differentiation, simultaneously NeuroD1 was involved in neural stem cells differentiation into neurons. Moreover, in vivo we found EA promoted NeuroD1-mediated neural stem cells differentiation via miR-146b. In addition, EA also could improve neurological deficits through miR-146b after ischemic stroke.

Conclusion: EA promotes the differentiation of endogenous neural stem cells via exosomal miR-146b to improve neurological injury after ischemic stroke.

LncRNA SNHG1 alleviated apoptosis and inflammation during ischemic stroke by targeting miR-376a and modulating CBS/H2S pathway

BACKGROUND

Ischemic stroke (IS) is a major public health issue causing mortality and disability and is more difficult to treat than other cerebral diseases. Previous study reported that miR-376a was upregulated in the serum of stroke patients, indicating that miR-376a played potential role in occurrence and development of stroke.

METHODS

IS cell model was induced by oxygen-glucose deprivation (OGD) exposed HCMEC/D3 cells. The mRNA level of SNHG1, miR-376a and inflammatory cytokines were detected by q-PCR. Protein level of CBS, apoptotic proteins were examined by Western blot. Apoptosis was analyzed by flow cytometry, and H₂S level was measured by kit. Interaction among lncRNA, miRNA and target gene was validated by luciferase assay.

RESULTS

Our research revealed that mRNA level of SNHG1 and CBS in HCMEC/D3 cells was downregulated while miR-376a was upregulated under OGD conditions. Further results demonstrated that miR-376a overexpression promoted apoptosis and inflammation while SNHG1 overexpressing alleviated such processes. Mechanistically, SNHG1 directly targeted miR-376a, and CBS was a target of miR-376a. Moreover, SNHG1 exert its function via inhibiting miR-376a to regulate CBS expression.

CONCLUSION

LncRNA SNHG1 depressed apoptosis and inflammation of IS cell model via inhibiting miR-376a and upregulating CBS/H₂S signal. These results show light on underlying mechanisms of IS and provide potential targets for IS therapy.

IRE1α inhibition attenuates neuronal pyroptosis via miR-125/NLRP1 pathway in a neonatal hypoxic-ischemic encephalopathy rat model

BACKGROUND

Inhibition of inositol-requiring enzyme-1 alpha (IRE1α), one of the sensor signaling proteins associated with endoplasmic reticulum (ER) stress, has been shown to alleviate brain injury and improve neurological behavior in a neonatal hypoxic-ischemic encephalopathy (HIE) rat model. However, there is no information about the role of IRE1α inhibitor as well as its molecular mechanisms in preventing neuronal pyroptosis induced by NLRP1 (NOD-, LRR- and pyrin domain-containing 1) inflammasome. In the present study, we hypothesized that IRE1α can degrade microRNA-125-b-2-3p (miR-125-b-2-3p) and activate NLRP1/caspased-1 pathway, and subsequently promote neuronal pyroptosis in HIE rat model.

METHODS

Ten-day old unsexed rat pups were subjected to hypoxia-ischemia (HI) injury, and the inhibitor of IRE1α, STF083010, was administered intranasally at 1 h after HI induction. AntimiR-125 or NLRP1 activation CRISPR was administered by intracerebroventricular (i.c.v) injection at 24 h before HI induction. Immunofluorescence staining, western blot analysis, reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR), brain infarct volume measurement, neurological function tests, and Fluoro-Jade C staining were performed.

RESULTS

Endogenous phosphorylated IRE1α (p-IRE1α), NLRP1, cleaved caspase-1, interleukin-1β (IL-1β), and interleukin-18 (IL-18) were increased and miR-125-b-2-3p was decreased in HIE rat model. STF083010 administration significantly upregulated the expression of miR-125-b-2-3p, reduced the infarct volume, improved neurobehavioral outcomes and downregulated the protein expression of NLRP1, cleaved caspase-1, IL-1β and IL-18. The protective effects of STF083010 were reversed by antimiR-125 or NLRP1 activation CRISPR.

CONCLUSIONS

IRE1α inhibitor, STF083010, reduced neuronal pyroptosis at least in part via miR-125/NLRP1/caspase-1 signaling pathway after HI.

Changes in Whole-Blood microRNA Profiles during the Onset and Treatment Process of Cerebral Infarction: A Human Study

Circulating miRNA species are promising symptom markers for various diseases, including cardiovascular disease. However, studies regarding their role in the treatment process are limited, especially concerning cerebral infarction. This study aimed to extract miRNA markers to investigate whether they reflect both onset and treatment process of cerebral infarction. A total of 22 patients (P-group) and 22 control subjects (C-group) were examined for their whole-blood miRNA profiles using DNA GeneChip™ miRNA 4.0 Array, with six patients examined after treatment (T-group). A total of 64 miRNAs were found to be differentially expressed between the C- and P-groups. Out of 64 miRNAs, the expression levels of two miRNAs correlated with hypertension. A total of 155 miRNAs were differentially expressed between the P- and T-groups. Five common miRNAs were found among the 64 and 155 miRNAs identified. Importantly, these common miRNAs were inversely regulated in each comparison (e.g., C < P > T), including miR-505-5p, which was previously reported to be upregulated in aortic stenosis patients. Our previous study using rat cerebral infarction models detected the downregulation of an apoptosis repressor, WDR26, which was repressed by one of the five miRNAs. Our results provide novel information regarding the miRNA-based diagnosis of cerebral infarction in humans. In particular, the five common miRNAs could be useful makers for the onset and the treatment process. Trial registration: This study was registered in the UMIN Clinical Trials Registry (UMIN000038321).

Mechanisms of Cardiovascular Disorders in Patients With Chronic Kidney Disease: A Process Related to Accelerated Senescence

Cardiovascular diseases (CVDs), especially those involving a systemic inflammatory process such as atherosclerosis, remain the leading cause of morbidity and mortality in patients with chronic kidney disease (CKD). CKD is a systemic condition affecting approximately 10% of the general population. The prevalence of CKD has increased over the past decades because of the aging of the population worldwide. Indeed, CVDs in patients with CKD constitute a premature form of CVD observed in the general population. Multiple studies indicate that patients with renal disease undergo accelerated aging, which precipitates the appearance of pathologies, including CVDs, usually associated with advanced age. In this review, we discuss several aspects that characterize CKD-associated CVDs, such as etiopathogenic elements that CKD patients share with the general population, changes in the cellular balance of reactive oxygen species (ROS), and the associated process of cellular senescence. Uremia-associated aging is linked with numerous changes at the cellular and molecular level. These changes are similar to those observed in the normal process of physiologic aging. We also discuss new perspectives in the study of CKD-associated CVDs and epigenetic alterations in intercellular signaling, mediated by microRNAs and/or extracellular vesicles (EVs), which promote vascular damage and subsequent development of CVD. Understanding the processes and factors involved in accelerated senescence and other abnormal intercellular signaling will identify new therapeutic targets and lead to improved methods of diagnosis and monitoring for patients with CKD-associated CVDs.

MicroRNAs in brain development and cerebrovascular pathophysiology

MicroRNAs (miRNAs) are a class of highly conserved non-coding RNAs with 21-25 nucleotides in length and play an important role in regulating gene expression at the posttranscriptional level via base-paring with complementary sequences of the 3'-untranslated region of the target gene mRNA, leading to either transcript degradation or translation inhibition. Brain-enriched miRNAs act as versatile regulators of brain development and function, including neural lineage and subtype determination, neurogenesis, synapse formation and plasticity, neural stem cell proliferation and differentiation, and responses to insults. Herein, we summarize the current knowledge regarding the role of miRNAs in brain development and cerebrovascular pathophysiology. We review recent progress of the miRNA-based mechanisms in neuronal and cerebrovascular development as well as their role in hypoxic-ischemic brain injury. These findings hold great promise, not just for deeper understanding of basic brain biology but also for building new therapeutic strategies for prevention and treatment of pathologies such as cerebral ischemia.