Brain and blood microRNA expression profiling of ischemic stroke, intracerebral hemorrhage, and kainate seizures

MiR-122 overexpression alleviates oxygen-glucose deprivation-induced neuronal injury by targeting sPLA2-IIA

Background

Ischemic stroke (IS) is a neurological disease with significant disability and mortality. MicroRNAs were proven to be associated with cerebral ischemia. Previous studies have demonstrated miR-122 downregulation in both animal models of IS and the blood of IS patients. Nonetheless, the role and mechanism of miR-122-5p in IS remain unclear.

Methods

We established primary human and mouse astrocytes, along with HT22 mouse hippocampal neuronal cells, through oxygen-glucose deprivation/reoxygenation (OGD/R) treatment. To assess the impact of miR-122, we employed CCK8 assays, flow cytometry, RT-qPCR, western blotting, and ELISA to evaluate cell viability, apoptosis, reactive oxygen species (ROS) generation, and cytokine expression. A dual-luciferase reporter gene assay was employed to investigate the interaction between miR-122 and sPLA2-IIA.

Results

Overexpression of miR-122 resulted in decreased apoptosis, reduced cleaved caspase-3 expression, and increased cell viability in astrocytes and HT22 cells subjected to OGD/R. RT-qPCR and ELISA analyses demonstrated a decrease in mRNA and cytokine levels of interleukin (IL)-6 and tumor necrosis factor (TNF)-α in both astrocytes and HT22 cells following miR-122 overexpression. Moreover, miR-122 overexpression reversed OGD/R-induced ROS levels and 8-OHdG formation in astrocytes. Additionally, miR-122 overexpression decreased the mRNA and protein expression of inducible nitric oxide synthase (iNOS). Furthermore, we found that miR-122 attaches to the 3'-UTR of sPLA2-IIA, thereby downregulate its expression.

Conclusion

Our study demonstrates that miR-122-mediated inhibition of sPLA2-IIA attenuates OGD/R-induced neuronal injury by suppressing apoptosis, alleviating post-ischemic inflammation, and reducing ROS production. Thus, the miR-122/sPLA2-IIA axis may represent a promising target for IS treatment.

The role of small extracellular vesicles and microRNA as their cargo in the spinal cord injury pathophysiology and therapy

Spinal cord injury (SCI) is a devastating condition with a complex pathology that affects a significant portion of the population and causes long-term consequences. After primary injury, an inflammatory cascade of secondary injury occurs, followed by neuronal cell death and glial scar formation. Together with the limited regenerative capacity of the central nervous system, these are the main reasons for the poor prognosis after SCI. Despite recent advances, there is still no effective treatment. Promising therapeutic approaches include stem cells transplantation, which has demonstrated neuroprotective and immunomodulatory effects in SCI. This positive effect is thought to be mediated by small extracellular vesicles (sEVs); membrane-bound nanovesicles involved in intercellular communication through transport of functional proteins and RNA molecules. In this review, we summarize the current knowledge about sEVs and microRNA as their cargo as one of the most promising therapeutic approaches for the treatment of SCI. We provide a comprehensive overview of their role in SCI pathophysiology, neuroprotective potential and therapeutic effect.

miRNAs in epilepsy: A review from molecular signatures to therapeutic intervention

Epilepsy is a medical disorder marked by sporadic seizures accompanied by alterations in consciousness. The molecular mechanisms responsible for epilepsy and the factors contributing to alterations in neuronal structure compromised apoptotic responses in neurons, and disturbances in regeneration pathways in glial cells remain unidentified. MicroRNAs (miRNAs) are short noncoding RNA that consist of a single strand. They typically contain 21 to 23 nucleotides. miRNAs participate in the process of RNA silencing and the regulation of gene expression after transcription by selectively binding to mRNA molecules that possess complementary sequences. The disruption of miRNA regulation has been associated with the development of epilepsy, and manipulating a single miRNA can impact various cellular processes, hence serving as a potent intervention approach. Despite existing obstacles in the delivery and safety of miRNA-based treatments, researchers are actively investigating the potential of miRNAs to operate as regulators of brain activity and as targets for treating and preventing epilepsy. Hence, the utilization of miRNA-based therapeutic intervention shows potential for future epilepsy management. The objective of our present investigation was to ascertain the involvement of miRNAs in the causation and advancement of epilepsy. Moreover, they have undergone scrutiny for their potential utilization in therapeutic intervention.

An Emerging Role for Enhancer RNAs in Brain Disorders

Noncoding DNA undergoes widespread context-dependent transcription to produce noncoding RNAs. In recent decades, tremendous advances in genomics and transcriptomics have revealed important regulatory roles for noncoding DNA elements and the RNAs that they produce. Enhancers are one such element that are well-established drivers of gene expression changes in response to a variety of factors such as external stimuli, cellular responses, developmental cues, and disease states. They are known to act at long distances, interact with multiple target gene loci simultaneously, synergize with other enhancers, and associate with dynamic chromatin architectures to form a complex regulatory network. Recent advances in enhancer biology have revealed that upon activation, enhancers transcribe long noncoding RNAs, known as enhancer RNAs (eRNAs), that have been shown to play important roles in enhancer-mediated gene regulation and chromatin-modifying activities. In the brain, enhancer dysregulation and eRNA transcription has been reported in numerous disorders from acute injuries to chronic neurodegeneration. Because this is an emerging area, a comprehensive understanding of eRNA function has not yet been achieved in brain disorders; however, the findings to date have illuminated a role for eRNAs in activity-driven gene expression and phenotypic outcomes. In this review, we highlight the breadth of the current literature on eRNA biology in brain health and disease and discuss the challenges as well as focus areas and strategies for future in-depth research on eRNAs in brain health and disease.

Tumor Suppressor MicroRNAs in Clinical and Preclinical Trials for Neurological Disorders

Cancers and neurological disorders are two major types of diseases in humans. We developed the concept called the "Aberrant Cell Cycle Disease (ACCD)" due to the accumulating evidence that shows that two different diseases share the common mechanism of aberrant cell cycle re-entry. The aberrant cell cycle re-entry is manifested as kinase/oncoprotein activation and tumor suppressor (TS) inactivation, which are associated with both tumor growth in cancers and neuronal death in neurological disorders. Therefore, some cancer therapies (e.g., kinase/oncogene inhibition and TS elevation) can be leveraged for neurological treatments. MicroRNA (miR/miRNA) provides a new style of drug-target binding. For example, a single tumor suppressor miRNA (TS-miR/miRNA) can bind to and decrease tens of target kinases/oncogenes, producing much more robust efficacy to block cell cycle re-entry than inhibiting a single kinase/oncogene. In this review, we summarize the miRNAs that are altered in both cancers and neurological disorders, with an emphasis on miRNA drugs that have entered into clinical trials for neurological treatment.

Tanshinone IIA Alleviates Traumatic Brain Injury by Reducing Ischemia‒Reperfusion via the miR-124-5p/FoxO1 Axis

Background

Cerebral ischemia-reperfusion injury is a common complication of ischemic stroke that affects the prognosis of patients with ischemic stroke. The lipid-soluble diterpene Tanshinone IIA, which was isolated from Salvia miltiorrhiza, has been indicated to reduce cerebral ischemic injury. In this study, we investigated the molecular mechanism of Tanshinone IIA in alleviating reperfusion-induced brain injury.

Methods

Middle cerebral artery occlusion animal models were established, and neurological scores, tetrazolium chloride staining, brain volume quantification, wet and dry brain water content measurement, Nissl staining, enzyme-linked immunosorbent assay, flow cytometry, western blotting, and reverse transcription-quantitative polymerase chain reaction were performed. The viability of cells was measured by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide assays, while cell damage was measured by lactate dehydrogenase release in the in vitro oxygen glucose deprivation model. In addition, enzyme-linked immunosorbent assay, flow cytometry, western blotting, and reverse transcription-quantitative polymerase chain reaction were used to evaluate the therapeutic effect of Tanshinone IIA on ischemia/reperfusion (I/R) induced brain injury, as well as its effects on the inflammatory response and neuronal apoptosis, in vivo and in vitro. Furthermore, this study validated the targeting relationship between miR-124-5p and FoxO1 using a dual luciferase assay. Finally, we examined the role of Tanshinone IIA in brain injury from a molecular perspective by inhibiting miR-124-5p or increasing FoxO1 levels.

Results

After treatment with Tanshinone IIA in middle cerebral artery occlusion-reperfusion (MCAO/R) rats, the volume of cerebral infarction was reduced, the water content of the brain was decreased, the nerve function of the rats was significantly improved, and the cell damage was significantly reduced. In addition, Tanshinone IIA effectively inhibited the I/R-induced inflammatory response and neuronal apoptosis, that is, it inhibited the expression of inflammatory cytokines IL-1β, IL-6, TNF-α, decreased the expression of apoptotic protein Bax and Cleaved-caspase-3, and promoted the expression of antiapoptotic protein Bcl-2. In vitro oxygen-glucose deprivation/reoxygenation (OGD/R) cell model, Tanshinone IIA also inhibited the expression of inflammatory factors in neuronal cells and inhibited the occurrence of neuronal apoptosis. In addition, Tanshinone IIA promoted the expression of miR-124-5p. Transfection of miR-124-5p mimic has the same therapeutic effect as Tanshinone IIA and positive therapeutic effect on OGD cells, while transfection of miR-124-5p inhibitor has the opposite effect. The targeting of miR-124-5p negatively regulates FoxO1 expression. Inhibition of miR-124-5p or overexpression of FoxO1 can weaken the inhibitory effect of Tanshinone IIA on brain injury induced by I/R, while inhibition of miR-124-5p and overexpression of FoxO1 can further weaken the effect of Tanshinone IIA.

Conclusion

Tanshinone IIA alleviates ischemic-reperfusion brain injury by inhibiting neuroinflammation through the miR-124-5p/FoxO1 axis. This finding provides a theoretical basis for mechanistic research on cerebral ischemia-reperfusion injury.

Circulating miRNAs as Novel Clinical Biomarkers in Temporal Lobe Epilepsy

Temporal lobe epilepsy (TLE) represents the most common form of refractory focal epilepsy. The identification of innovative clinical biomarkers capable of categorizing patients with TLE, allowing for improved treatment and outcomes, still represents an unmet need. Circulating microRNAs (c-miRNAs) are short non-coding RNAs detectable in body fluids, which play crucial roles in the regulation of gene expression. Their characteristics, including extracellular stability, detectability through non-invasive methods, and responsiveness to pathological changes and/or therapeutic interventions, make them promising candidate biomarkers in various disease settings. Recent research has investigated c-miRNAs in various bodily fluids, including serum, plasma, and cerebrospinal fluid, of TLE patients. Despite some discrepancies in methodologies, cohort composition, and normalization strategies, a common dysregulated signature of c-miRNAs has emerged across different studies, providing the basis for using c-miRNAs as novel biomarkers for TLE patient management.

Malignancy-associated ischemic stroke: Implications for diagnostic and therapeutic workup

BACKGROUND

Patients with malignancies have an increased risk of suffering ischemic stroke via several mechanisms such as coagulation dysfunction and other malignancy-related effects as well as iatrogenic causes. Moreover, stroke can be the first sign of an occult malignancy, termed as malignancy-associated ischemic stroke (MAS). Therefore, timely diagnostic assessment and targeted management of this complex clinical situation are critical.

FINDINGS

Patients with both stroke and malignancy have atypical ages, risk factors, and often exhibit malignancy-related symptoms and multiple lesions on neuroimaging. New biomarkers such as eicosapentaenoic acid and blood mRNA profiles may help in distinguishing MAS from other strokes. In terms of treatment, malignancy should not be considered a contraindication, given comparable rates of recanalization and complications between stroke patients with or without malignancies.

CONCLUSION

In this review, we summarize the latest developments in diagnosing and managing MAS, especially stroke with occult malignancies, and provide new recommendations from recently emerged clinical evidence for diagnostic and therapeutic workup strategies.

The exo-microRNA (miRNA) signaling pathways in pathogenesis and treatment of stroke diseases: Emphasize on mesenchymal stem cells (MSCs)

A major factor in long-term impairment is stroke. Patients with persistent stroke and severe functional disabilities have few therapy choices. Long noncoding RNAs (lncRNAs) may contribute to the regulation of the pathophysiologic processes of ischemic stroke as shown by altered expression of lncRNAs and microRNA (miRNAs) in blood samples of acute ischemic stroke patients. On the other hand, multipotent mesenchymal stem cells (MSCs) increase neurogenesis, and angiogenesis, dampen neuroinflammation, and boost brain plasticity to improve functional recovery in experimental stroke models. MSCs can be procured from various sources such as the bone marrow, adipose tissue, and peripheral blood. Under the proper circumstances, MSCs can differentiate into a variety of mature cells, including neurons, astrocytes, and oligodendrocytes. Accordingly, the capability of MSCs to exert neuroprotection and also neurogenesis has recently attracted more attention. Nowadays, lncRNAs and miRNAs derived from MSCs have opened new avenues to alleviate stroke symptoms. Accordingly, in this review article, we examined various studies concerning the lncRNAs and miRNAs' role in stroke pathogenesis and delivered an overview of the therapeutic role of MSC-derived miRNAs and lncRNAs in stroke conditions.

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.

Circulating microRNAs from plasma as preclinical biomarkers of epileptogenesis and epilepsy

Epilepsy frequently develops as a result of brain insult; however, there are no tools allowing to predict which patients suffering from trauma will eventually develop epilepsy. microRNAs are interesting candidates for biomarkers, as several of them have been described to change their levels in the brains, and in the plasma of epileptic subjects. This study was conducted to evaluate the usefulness of plasma miRNAs as epileptogenesis/epilepsy biomarkers. In our studies, we used a rat model of temporal lobe epilepsy. An epileptogenic insult was status epilepticus evoked by stimulation of the left lateral nucleus of the amygdala. Next, animals were continuously video and EEG monitored for 3 months. Blood was collected at 14, 30, 60, and 90 days after stimulation. Blood plasma was separated and miRNA levels were analyzed. We compared miRNA levels between sham-operated and stimulated animals, and between animals with high and low numbers of seizures. We propose three miRNAs that could be biomarkers of epilepsy: miR-671, miR-9a-3p and miR-7a-5p. According to us, miR-206-5p is a potential biomarker of epileptogenesis, and miR-221-3p is a potential biomarker of epilepsy severity. We think that these five miRNAs can be considered in the future as potential treatment targets.

Role of regulatory non-coding RNAs in traumatic brain injury

Traumatic brain injury (TBI) is a potentially fatal health event that cannot be predicted in advance. After TBI occurs, it can have enduring consequences within both familial and social spheres. Yet, despite extensive efforts to improve medical interventions and tailor healthcare services, TBI still remains a major contributor to global disability and mortality rates. The prompt and accurate diagnosis of TBI in clinical contexts, coupled with the implementation of effective therapeutic strategies, remains an arduous challenge. However, a deeper understanding of changes in gene expression and the underlying molecular regulatory processes may alleviate this pressing issue. In recent years, the study of regulatory non-coding RNAs (ncRNAs), a diverse class of RNA molecules with regulatory functions, has been a potential game changer in TBI research. Notably, the identification of microRNAs (miRNAs), long non-coding RNAs (lncRNAs), circular RNAs (circRNAs), and other ncRNAs has revealed their potential as novel diagnostic biomarkers and therapeutic targets for TBI, owing to their ability to regulate the expression of numerous genes. In this review, we seek to provide a comprehensive overview of the functions of regulatory ncRNAs in TBI. We also summarize regulatory ncRNAs used for treatment in animal models, as well as miRNAs, lncRNAs, and circRNAs that served as biomarkers for TBI diagnosis and prognosis. Finally, we discuss future challenges and prospects in diagnosing and treating TBI patients in the clinical settings.

Unveiling the regulatory role of miRNAs in stroke pathophysiology and diagnosis

Stroke, a major global cause of mortality, leads to a range of problems for those who survive. Besides its brutal events, stroke also tends to have a characteristic of recurrence, making it a complex disease involving intricate regulatory networks. One of the major cellular regulators is the non-coding RNAs (ncRNA), specifically microRNAs (miRNAs), thus the possible functions of miRNAs in the pathogenesis of stroke are discussed as well as the possibility of using miRNA-based therapeutic approaches. Firstly, the molecular mechanisms by which miRNAs regulate vital physiological processes, including synaptic plasticity, oxidative stress, apoptosis, and the integrity of the blood-brain barrier (BBB) are reviewed. The miRNA indirectly impacts stroke outcomes by regulating BBB function and angiogenesis through the targeting of transcription factors and angiogenic factors. In addition, the tendency for some miRNAs to be upregulated in response to hypoxia, which is a prevalent phenomenon in stroke and various neurological disorders, highlights the possibility that it controls hypoxia-inducible factor (HIF) signaling and angiogenesis, thereby influencing the integrity of the BBB as examples of the discussed mechanisms. Furthermore, this review explores the potential therapeutic targets that miRNAs may offer for stroke recovery and highlights their promising capacity to alleviate post-stroke complications. This review provides researchers and clinicians with valuable resources since it attempts to decipher the complex network of miRNA-mediated mechanisms in stroke. Additionally, the review addresses the interplay between miRNAs and stroke risk factors as well as clinical applications of miRNAs as diagnostic and prognostic markers.

circ_0000018 downregulation peripherally ameliorates neuroprotection against acute ischemic stroke through the miR‑871/BCL2L11 axis

Acute ischemic stroke (AIS) is a common acute cerebrovascular disease. Circular RNAs (circRNAs) have been demonstrated to have critical functions in a wide range of physiological processes and disorders in humans. However, their precise function in ischemic stroke (IS) remains largely unknown. The present study explored the function and potential mechanisms of circ_0000018 in AIS in vivo and in vitro. The cerebral ischemia/reperfusion injury model was established in vivo and in vitro using the oxygen‑glucose deprivation (OGD/R) and transient middle cerebral artery occlusion (tMCAO) methods. Subsequently, the impact of circ_0000018 on cerebral ischemia/reperfusion injury was assessed using various techniques, including TTC staining, quantitative PCR, western blotting, cell counting kit‑8 assay, Annexin V‑FITC Apoptosis Detection Kit, luciferase reporter gene assays, and others. The levels of circ_0000018 were markedly increased in the OGD/R‑treated neuronal cells and in a mouse model of tMCAO. The blocking of microRNA (miR)‑871 by circ_0000018 promoted Bcl‑2‑like protein 11 (BCL2L11) expression to increase neuronal cell damage. Furthermore, circ_0000018 knockdown significantly improved neuronal cell viability and attenuated OGD/R‑treated neuronal cell death. Meanwhile, circ_0000018 knockdown improved brain infarct volume and neuronal apoptosis in tMCAO mice. The present study found that circ_0000018 knockdown relieved cerebral ischemia‑reperfusion injury progression in vitro and in vivo. Mechanistically, circ_0000018 regulated the levels of BCL2L11 by sponging miR‑871.

The 100 most-cited manuscripts in epilepsy epigenetics: a bibliometric analysis

PURPOSE

The top citation article reflects the developmental milestone of a given field. The purpose of this bibliometric analysis was to identify and assess the 100 most-cited (T100) articles on the epigenetics mechanism of epilepsy.

METHODS

The Web of Science Core Collection (WoSCC) database was used to investigate, and search terms related to epilepsy epigenetics were compiled. Results were ranked according to citation number. The publication year, citation density, authorship, journal, country, institution, manuscript type, theme, and clinical topics were further evaluated.

RESULTS

The Web of Science search returned a total of 1231 manuscripts. The number of citations for a manuscript ranges from 739 to 75. The greatest number of manuscripts in the top 100 was published in the Human Molecular Genetics and Neurobiology of Disease (n = 4). The journal with the highest 2021 impact factor was Nature Medicine (IF = 87.244). The most-cited paper by Aid et al. reported a new nomenclature for mouse and rat BDNF gene and its expression profiles. Most manuscripts were original articles (n = 69), of which 52 (75.4%) report findings of basic scientific work. The most prevalent theme was microRNA (n = 29), and the most popular clinical topic was temporal lobe epilepsy (n = 13).

CONCLUSIONS

The research on the epigenetics mechanism of epilepsy was in its infancy but full of potential. The developmental history and current achievements of hot themes, including microRNA, DNA methylation, and temporal lobe epilepsy, were overviewed. This bibliometric analysis provides useful information and insight for researchers when launching new projects.

Rats in Epilepsy Research: A Bibliometric Analysis of Citations Between 1969 and 2020 on Experimental Models in Epilepsy

Epilepsy stands as a prominent neurological disorder, affecting a substantial number of individuals who, unfortunately, do not respond to conventional antiepileptic medications. To unravel the intricate mechanisms underlying epileptic seizures and explore potential therapeutic avenues, researchers have turned to animal models. Among these models, rats have emerged as one of the cornerstones of epilepsy research. This bibliometric analysis embarks on the crucial task of delving into the role of rat models in deciphering the mysteries of epileptic seizures and, notably, pinpointing the most prevalent models in use. Our study harnessed Scopus' citation tracking feature to review a range of research papers dating from 1969 to 2020, all dedicated to the exploration of epileptic seizures in rats. The citations that emerged from this rigorous process were subjected to thematic coding, primarily centered around the specific epileptic animal models employed, and subsequently, comprehensive descriptive statistics were computed. In this effort, we found a total of 1,318 publications that explore the world of rat studies, accumulating a substantial citation count of 44,824 references. This analysis illuminated the invaluable role that research employing rat models has played in shaping our current clinical understanding of epileptic seizures. Notably, several models have emerged as predominant forces in this field, including those induced by pilocarpine, pentylenetetrazole (PTZ), kainic acid (KA), electric kindling, and electroshock. This bibliometric exploration serves as a resounding reminder of the pivotal position that rat models occupy in advancing our comprehension of epilepsy. These findings resonate strongly, underscoring the continued importance of directing research and development funding toward this debilitating disorder, with the ultimate aim of maximizing the benefits for the patients grappling with this condition. The potential to revolutionize our approach to epilepsy and enhance the quality of life for those affected remains a beacon of hope, illuminated by the contributions of these tireless researchers and their trusty rat companions.

Role of Crosstalk between Glial Cells and Immune Cells in Blood-Brain Barrier Damage and Protection after Acute Ischemic Stroke

Blood-brain barrier (BBB) damage is the main pathological basis for acute ischemic stroke (AIS)-induced cerebral vasogenic edema and hemorrhagic transformation (HT). Glial cells, including microglia, astrocytes, and oligodendrocyte precursor cells (OPCs)/oligodendrocytes (OLs) play critical roles in BBB damage and protection. Recent evidence indicates that immune cells also have an important role in BBB damage, vasogenic edema and HT. Therefore, regulating the crosstalk between glial cells and immune cells would hold the promise to alleviate AIS-induced BBB damage. In this review, we first introduce the roles of glia cells, pericytes, and crosstalk between glial cells in the damage and protection of BBB after AIS, emphasizing the polarization, inflammatory response and crosstalk between microglia, astrocytes, and other glia cells. We then describe the role of glial cell-derived exosomes in the damage and protection of BBB after AIS. Next, we specifically discuss the crosstalk between glial cells and immune cells after AIS. Finally, we propose that glial cells could be a potential target for alleviating BBB damage after AIS and we discuss some molecular targets and potential strategies to alleviate BBB damage by regulating glial cells after AIS.

The dysregulation of miRNAs in epilepsy and their regulatory role in inflammation and apoptosis

Epilepsy is a neurological disorder that impacts millions of people worldwide, and it is characterized by the occurrence of recurrent seizures. The pathogenesis of epilepsy is complex, involving dysregulation of various genes and signaling pathways. MicroRNAs (miRNAs) are a group of small non-coding RNAs that play a vital role in the regulation of gene expression. They have been found to be involved in the pathogenesis of epilepsy, acting as key regulators of neuronal excitability and synaptic plasticity. In recent years, there has been a growing interest in exploring the miRNA regulatory network in epilepsy. This review summarizes the current knowledge of the regulatory miRNAs involved in inflammation and apoptosis in epilepsy and discusses its potential as a new avenue for developing targeted therapies for the treatment of epilepsy.

Identification of a miRNA-mRNA regulatory network for post-stroke depression: a machine-learning approach

Objective

The study aimed to explore the miRNA and mRNA biomarkers in post-stroke depression (PSD) and to develop a miRNA-mRNA regulatory network to reveal its potential pathogenesis.

Methods

The transcriptomic expression profile was obtained from the GEO database using the accession numbers GSE117064 (miRNAs, stroke vs. control) and GSE76826 [mRNAs, late-onset major depressive disorder (MDD) vs. control]. Differentially expressed miRNAs (DE-miRNAs) were identified in blood samples collected from stroke patients vs. control using the Linear Models for Microarray Data (LIMMA) package, while the weighted correlation network analysis (WGCNA) revealed co-expressed gene modules correlated with the subject group. The intersection between DE-miRNAs and miRNAs identified by WGCNA was defined as stroke-related miRNAs, whose target mRNAs were stroke-related genes with the prediction based on three databases (miRDB, miRTarBase, and TargetScan). Using the GSE76826 dataset, the differentially expressed genes (DEGs) were identified. Overlapped DEGs between stroke-related genes and DEGs in late-onset MDD were retrieved, and these were potential mRNA biomarkers in PSD. With the overlapped DEGs, three machine-learning methods were employed to identify gene signatures for PSD, which were established with the intersection of gene sets identified by each algorithm. Based on the gene signatures, the upstream miRNAs were predicted, and a miRNA-mRNA network was constructed.

Results

Using the GSE117064 dataset, we retrieved a total of 667 DE-miRNAs, which included 420 upregulated and 247 downregulated ones. Meanwhile, WGCNA identified two modules (blue and brown) that were significantly correlated with the subject group. A total of 117 stroke-related miRNAs were identified with the intersection of DE-miRNAs and WGCNA-related ones. Based on the miRNA-mRNA databases, we identified a list of 2,387 stroke-related genes, among which 99 DEGs in MDD were also embedded. Based on the 99 overlapped DEGs, we identified three gene signatures (SPATA2, ZNF208, and YTHDC1) using three machine-learning classifiers. Predictions of the three mRNAs highlight four miRNAs as follows: miR-6883-5p, miR-6873-3p, miR-4776-3p, and miR-6738-3p. Subsequently, a miRNA-mRNA network was developed.

Conclusion

The study highlighted gene signatures for PSD with three genes (SPATA2, ZNF208, and YTHDC1) and four upstream miRNAs (miR-6883-5p, miR-6873-3p, miR-4776-3p, and miR-6738-3p). These biomarkers could further our understanding of the pathogenesis of PSD.

Dysregulation of Serum MicroRNA after Intracerebral Hemorrhage in Aged Mice

Stroke is one of the most common diseases that leads to brain injury and mortality in patients, and intracerebral hemorrhage (ICH) is the most devastating subtype of stroke. Though the prevalence of ICH increases with aging, the effect of aging on the pathophysiology of ICH remains largely understudied. Moreover, there is no effective treatment for ICH. Recent studies have demonstrated the potential of circulating microRNAs as non-invasive diagnostic and prognostic biomarkers in various pathological conditions. While many studies have identified microRNAs that play roles in the pathophysiology of brain injury, few demonstrated their functions and roles after ICH. Given this significant knowledge gap, the present study aims to identify microRNAs that could serve as potential biomarkers of ICH in the elderly. To this end, sham or ICH was induced in aged C57BL/6 mice (18–24 months), and 24 h post-ICH, serum microRNAs were isolated, and expressions were analyzed. We identified 28 significantly dysregulated microRNAs between ICH and sham groups, suggesting their potential to serve as blood biomarkers of acute ICH. Among those microRNAs, based on the current literature, miR-124-3p, miR-137-5p, miR-138-5p, miR-219a-2-3p, miR-135a-5p, miR-541-5p, and miR-770-3p may serve as the most promising blood biomarker candidates of ICH, warranting further investigation.

Direct targeting of DOCK4 by miRNA-181d in oxygen-glucose deprivation/reoxygenation-mediated neuronal injury

The miRNA-181 (miR-181) family regulates neuronal persistence during cerebral ischemia/reperfusion injury (CI/RI). Since the effect of miR-181d on CI/RI has never been studied, the current work sought to determine the involvement of miR-181d in neuronal apoptosis after brain I/R injury. To replicate in vivo and in vitro CI/RI, a transient middle cerebral artery occlusion (tMCAO) model in rats and an oxygen-glucose deficiency/reoxygenation (OGD/R) model in neuro 2A cells were developed. In both in vivo and in vitro stroke models, the expression of miR-181d was considerably higher. miR-181d suppression reduced apoptosis and oxidative stress in OGD/R-treated neuroblastoma cells, but miR-181d overexpression increased both. Furthermore, it was observed that miR-181d has a direct target in dedicator of cytokinesis 4 (DOCK4). The overexpression of DOCK4 partially overcame cell apoptosis and oxidative stress induced by miR-181d upregulation and OGD/R injury. Furthermore, the DOCK4 rs2074130 mutation was related to lower DOCK4 levels in ischemic stroke (IS) peripheral blood and higher susceptibility to IS. These findings suggest that downregulating miR-181d protects neurons from ischemic damage by targeting DOCK4, implying that the miR-181d/DOCK4 axis might be a novel therapeutic target for IS.

A short peptide exerts neuroprotective effects on cerebral ischemia-reperfusion injury by reducing inflammation via the miR-6328/IKKβ/NF-κB axis

BACKGROUND

Despite considerable efforts, ischemic stroke (IS) remains a challenging clinical problem. Therefore, the discovery of effective therapeutic and targeted drugs based on the underlying molecular mechanism is crucial for effective IS treatment.

METHODS

A cDNA-encoding peptide was cloned from RNA extracted from Rana limnocharis skin, and the mature amino acid sequence was predicted and synthesized. Hemolysis and acute toxicity of the peptide were tested. Furthermore, its neuroprotective properties were evaluated using a middle cerebral artery occlusion/reperfusion (MCAO/R) model in rats and an oxygen-glucose deprivation/reperfusion (OGD/R) model in neuron-like PC12 cells. The underlying molecular mechanisms were explored using microRNA (miRNA) sequencing, quantitative real-time polymerase chain reaction, dual-luciferase reporter gene assay, and western blotting.

RESULTS

A new peptide (NP1) with an amino acid sequence of 'FLPAAICLVIKTC' was identified. NP1 showed no obvious toxicities in vivo and in vitro and was able to cross the blood-brain barrier. Intraperitoneal administration of NP1 (10 nmol/kg) effectively reduced the volume of cerebral infarction and relieved neurological dysfunction in MCAO/R model rats. Moreover, NP1 significantly alleviated the decrease in viability and increase in apoptosis of neuron-like PC12 cells induced by OGD/R. NP1 effectively suppressed inflammation by reducing interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) levels in vitro and in vivo. Furthermore, NP1 up-regulated the expression of miR-6328, which, in turn, down-regulated kappa B kinase β (IKKβ). IKKβ reduced the phosphorylation of nuclear factor-kappa B p65 (NF-κB p65) and inhibitor of NF-κB (I-κB), thereby inhibiting activation of the NF-κB pathway.

CONCLUSIONS

The newly discovered non-toxic peptide NP1 ('FLPAAICLVIKTC') exerted neuroprotective effects on cerebral ischemia-reperfusion injury by reducing inflammation via the miR-6328/IKKβ/NF-κB axis. Our findings not only provide an exogenous peptide drug candidate and endogenous small nucleic acid drug candidate but also a new drug target for the treatment of IS. This study highlights the importance of peptides in the development of new drugs, elucidation of pathological mechanisms, and discovery of new drug targets.

The long-lasting effects of early life adversities are sex dependent: The signature of miR-34a

BACKGROUND

Exposure to early life adversities (ELA) can influence a plethora of biological mechanisms leading to stress-related disorders later in life through epigenetic mechanisms, such as microRNAs (miRs). MiR-34 is a critical modulator of stress response and stress-induced pathologies and a link between ELA and miR-34a has been reported.

METHODS

Here using our well-established model of ELA (Repeated Cross Fostering) we investigate the behavioral long-term effects of ELA in male and female mice. We also assess basal and ELA-induced miR-34a expression in adult mice and investigate whether ELA affects the later miR-34a response to adult acute stress exposure across brain areas (medial preFrontal Cortex, Dorsal Raphe Nuclei) and peripheral organs (heart, plasma) in animals from both sexes. Finally, based on our previous data demonstrating the critical role of Dorsal Raphe Nuclei miR-34a expression in serotonin (5-HT) transmission, we also investigated prefrontal-accumbal 5-HT outflow induced by acute stress exposure in ELA and Control females by in vivo intracerebral microdialysis.

RESULTS

ELA not just induces a depressive-like state as well as enduring changes in miR-34a expression, but also alters miR-34a expression in response to adult acute stress exclusively in females. Finally, altered DRN miR-34a expression is associated with prefrontal-accumbal 5-HT release under acute stress exposure in females.

LIMITATIONS

Translational study on humans is necessary to verify the results obtained in our animal models of ELA-induced depression.

CONCLUSIONS

This is the first evidence showing long-lasting sex related effects of ELA on brain and peripheral miR-34a expression levels in an animal model of depression-like phenotype.

HDAC Inhibitor SAHA Alleviates Pyroptosis by up-regulating miR-340 to Inhibit NEK7 Signaling in Subarachnoid Hemorrhage

BACKGROUND

Subarachnoid hemorrhage (SAH) is a cerebral hemorrhagic disease with a high disability and fatality rate. Cell pyroptosis is involved in the brain injury following SAH. Here, we explored the effect of HDAC inhibitor SAHA against cell pyroptosis after SAH.

METHODS

The rat SAH model was established by endovascular perforation and the rat microglia were treated with 25 μm oxyhemoglobin (OxyHb) for 24 h to mimic SAH model in vitro. Neurological score and brain edema were assessed in rat SAH model. TUNEL staining detected apoptosis. qRT-PCR and western blotting were employed to detect expression levels of miR-340, NEK7 and inflammatory cytokines. ELISA assay determined the secretion of IL-1β and IL-18 in rat serum and cell supernatant. A lactate dehydrogenase (LDH) kit measured the LDH activity in rat primary microglia. Microglia pyroptosis was detected by flow cytometry. RIP and dual luciferase reporter assays confirmed the binding relationship between miR-340 and NEK7.

RESULTS

SAHA alleviated neurological dysfunction, inflammatory injury and microglia pyroptosis in SAH rats. SAHA suppressed LDH release, inflammatory factor expression and pyroptosis in microglia treated with OxyHb. Meanwhile, SAHA increased miR-340 expression and inhibited NEK7 level in vivo and in vitro SAH models. Further, miR-340 directly targeted NEK7 to inhibit the NLRP3 signaling pathway. Knockdown of miR-340 or overexpression of NEK7 reversed the suppressive effects of SAHA on microglia inflammation and pyroptosis. Additionally, knockdown of NEK7 impaired microglia inflammation and pyroptosis induced by miR-340 inhibitor.

CONCLUSION

HDAC inhibitor SAHA ameliorates microglia pyroptosis in SAH through triggering miR-340 expression to suppress NEK7 signaling. This novel mechanism provides promise for SAHA in SAH treatment.

Stem Cell-derived Extracellular Vesicles: A Promising Nano Delivery Platform to the Brain?

A very important cause of the frustration with drug therapy for central nervous system (CNS) diseases is the failure of drug delivery. The blood-brain barrier (BBB) prevents most therapeutic molecules from entering the brain while maintaining CNS homeostasis. Scientists are keen to develop new brain drug delivery systems to solve this dilemma. Extracellular vesicles (EVs), as a class of naturally derived nanoscale vesicles, have been extensively studied in drug delivery due to their superior properties. This review will briefly present current brain drug delivery strategies, including invasive and non-invasive techniques that target the brain, and the application of nanocarriers developed for brain drug delivery in recent years, especially EVs. The cellular origin of EVs affects the surface protein, size, yield, luminal composition, and other properties of EVs, which are also crucial in determining whether EVs are useful as drug carriers. Stem cell-derived EVs, which inherit the properties of parental cells and avoid the drawbacks of cell therapy, have always been favored by researchers. Thus, in this review, we will focus on the application of stem cell-derived EVs for drug delivery in the CNS. Various nucleic acids, proteins, and small-molecule drugs are loaded into EVs with or without modification and undergo targeted delivery to the brain to achieve their therapeutic effects. In addition, the challenges facing the clinical application of EVs as drug carriers will also be discussed. The directions of future efforts may be to improve drug loading efficiency and precise targeting.

Relationship Between MicroRNA Signature and Arterial Stiffness in Patients With Ischemic Stroke

BACKGROUND AND PURPOSE

We investigated whether circulating microRNAs (miRNAs) is associated with arterial stiffness in patients with acute ischemic stroke.

METHODS

We recruited patients with acute ischemic stroke who were admitted to a university hospital stroke center and underwent carotid-femoral pulse wave velocity (cfPWV) measurement using SphygmoCor (AtCor Medical, Sydney, Australia) and brachial-ankle PWV using a volume-plethysmography device (VP-1000, Omron Colin, Komaki, Japan). Circulating miRNAs were measured in venous blood samples stored in EDTA. We selected five miRNAs (miR-17, miR-93, miR-450, miR-629, and let-7i) related to atherosclerosis based on a literature review. Pearson's correlation analysis was applied to the correlations between miRNAs and arterial stiffness parameters. Finally, multivariable linear regression analysis was performed to identify the independent factors for cfPWV.

RESULTS

This study included 70 patients (age=71.1±10.3 years [mean±SD], 29 females). The expression levels of miR-93 (r=-0.27, p=0.049) and let-7i (r=-0.27, p=0.039) were inversely correlated with cfPWV. Multivariable linear regression analysis including age, hypertension, and estimated glomerular filtration rate showed that let-7i was independently related with cfPWV (standardized coefficient=-0.262, p=0.036). Correlation analysis indicated that let-7i was positively associated with visceral muscle Hounsfield units on computed tomography (r=0.264, p=0.043).

CONCLUSIONS

The expression level of let-7i was independently related to arterial stiffness in patients with cerebral infarction, suggesting that it plays a pathophysiological role in atherosclerosis.

The Role of Mitochondria-Targeting miRNAs in Intracerebral Hemorrhage

Non-traumatic intracerebral hemorrhage (ICH) is the most common type of hemorrhagic stroke, most often occurring between the ages of 45 and 60. Arterial hypertension (AH) is most often the cause of ICH, followed by atherosclerosis, blood diseases, inflammatory changes in cerebral vessels, intoxication and vitamin deficiencies. Cerebral hemorrhage can occur by diapedesis or as a result of a ruptured vessel. AH is difficult to treat, requires surgery and can lead to disability or death. One of the important directions in the study of the pathogenesis of ICH is mitochondrial dysfunction and its regulation. The key role of mitochondrial dysfunction in AH and atherosclerosis, as well as in the development of brain damage after hemorrhage, has been acknowledged. MicroRNAs (miRNAs) are a class of non-coding RNAs (about 18-22 nucleotides) that regulate a variety of biological processes including cell differentiation, proliferation, apoptosis, etc., primarily through gene repression. There is growing evidence to support dysregulated miRNAs in various cardiovascular diseases, including ICH. Further, the realization of miRNAs within mitochondrial compartment has challenged the traditional knowledge of signaling pathways involved in the regulatory network of cardiovascular diseases. However, the role of miRNAs in mitochondrial dysfunction for ICH is still under-appreciated, with comparatively much lesser studies and investigations reported, than those in other cardiovascular diseases. In this review, we summarize the up-to-date findings on the published role miRNAs in mitochondrial function for ICH, and the potential use of miRNAs in clinical settings, such as potential therapeutic targets and non-invasive diagnostic/prognostic biomarker tools.

Circular RNA circPRDX3 mediates neuronal survival apoptosis in ischemic stroke by targeting miR-641 and NPR3

OBJECTIVE

circPRDX3 is a circular RNA (circRNA) that has received little attention yet. The purpose of this research is to elucidate circPRDX3 expression pattern and its underlying network in ischemic stroke (IS).

METHODS

Oxygen-glucose deprivation on/reoxygenation (OGD/R) and mice model of middle cerebral artery occlusion (MCAO) were used to generate IS model in N2a cells or mice, respectively. Expression levels of circPRDX3, miR-641, Natriuretic Peptide Receptor 3 (NPR3), and members of the mitogen-activated protein kinases (MAPK) pathway were determined using real-time quantitative PCR (qRT-PCR) and western blot. Cell viability was assessed by CCK-8 assay and apoptosis was evaluated using TUNEL staining and flow cytometry. Molecule-molecule interactions were verified by dual luciferase and RNA immunoprecipitation (RIP) assays. The infarcted area was depicted by Triphenyl tetrazolium chloride (TTC) staining and the level of neurological function was measured using National Institute of Health stroke scale (NIHSS).

RESULTS

CircPRDX3 and NPR3 were shown to be considerably downregulated in IS samples, as well as OGD/R cells or MCAO mice, while miR-641 was found to be significantly upregulated. A circPRDX3/miR-641/NPR3 mechinary was verified using luciferase and RIP assays. Overexpression of circPRDX3 dramatically reduced miR-641 expression and increased NPR3 expression, boosting cell survival and lowering apoptosis in an OGD/R model, either with inactivated MAPK signaling pathways. Moreover, overexpression of circPRDX3 lowered infarct volume and enhanced neurobehavioral outcomes in mice after MCAO, and these protective effects were dramatically abrogated by depletion of NPR3.

CONCLUSION

Altogether, circPRDX3 inhibited the development of IS by sponging miR-641, hence increasing NPR3 expression and inactivating MAPK pathway. These results may aid in the search of potential therapy targets for IS.

Association of Thrombin Generation With Leukocyte Inflammatory Profile in Patients With Acute Ischemic Stroke

BACKGROUND AND OBJECTIVES

Thrombosis is central to the pathogenesis of acute ischemic stroke, with higher thrombin generation being associated with increased stroke risk. The immune system may contribute to thrombin generation in stroke and thus may offer novel strategies for stroke prevention. This study addresses the research question regarding the relationship of thrombin generation to leukocyte gene expression in patients with acute ischemic stroke.

METHODS

We isolated RNA from whole blood and examined the relationship to thrombin generation capacity in patients with acute ischemic stroke. Due to its effects on thrombin generation, patients on anticoagulants were excluded from the study. The relationship of gene expression with peak thrombin was evaluated by analysis of covariance across peak thrombin quartiles adjusted for sex and age.

RESULTS

In 97 patients with acute ischemic stroke, peak thrombin was variable, ranging from 252.0 to 752.4 nM. Increased peak thrombin was associated with differences in thromboinflammatory leukocyte gene expression, including a decrease in ADAM metallopeptidase with thrombospondin type 1 motif 13 and an increase in nuclear factor κB (NF-κB)-activating protein, protein disulfide isomerase family A member 5, and tissue factor pathway inhibitor 2. Pathways associated with peak thrombin included interleukin 6 signaling, thrombin signaling, and NF-κB signaling. A linear discriminant analysis model summarizing the immune activation associated with peak thrombin in a first cohort of stroke could distinguish patients with low peak thrombin from high peak thrombin in a second cohort of 112 patients with acute ischemic stroke.

DISCUSSION

The identified genes and pathways support a role of the immune system contributing to thrombus formation in patients with stroke. These may have relevance to antithrombotic strategies for stroke prevention.

Circulating endothelial microvesicles and their carried miR-125a-5p: potential biomarkers for ischaemic stroke

Background

Endothelial microvesicles (EMVs) are closely associated with the status of endothelial cells (ECs). Our earlier study has shown that EMVs could exert protective roles in ECs by transferring their carried miR-125a-5p. However, whether circulating EMVs and their carried miR-125a-5p can be used as biomarkers in ischaemic stroke (IS) are remain unknown.

Methods

We recruited 72 subjects with IS, 60 subjects with high stroke risk and 56 age-matched controls. The circulating EMVs and their carried miR-125a-5p (EMV-miR-125a-5p) levels were detected. We used microRNA (miR) array to study expression changes of miRs in plasma EMVs samples of three IS patients and three matched healthy controls. Transient middle cerebral artery occlusion (tMCAO) was used to establish IS mouse model.

Results

EMVs level was obviously elevated in IS patients, with the highest level in acute stage, and was positively related to carotid plaque, carotid intima–media thickness (IMT), National Institutes of Health Stroke Scale (NIHSS), infarct volume. On the contrary, we observed that EMV-miR-125a-5p level was obviously reduced in IS, with the lowest level in acute stage, and was negatively correlated with carotid plaque, IMT, NIHSS scores, infarct volume. EMVs and EMV-miR-125a-5p levels were closely related with large artery atherosclerosis subgroup. Importantly, EMVs and EMV-miR-125a-5p levels could serve as independent risk factors, and receiver operating characteristic curve achieved an area under curve (AUC) of 0.720 and 0.832 for IS, respectively, and elevated to 0.881 after their combination. In IS mouse model, control EMVs or n-EMVs administration could decrease the infarct volume and neurological deficit score, while increase the cerebral blood flow of IS mice compared with vehicle group, while IS EMVs or oxygen and glucose deprivation (OGD)-EMVs administration aggravated the tMCAO induced ischaemic injury. In addition, we observed that OGD EMVmiR-125a-5p could partially ameliorate the OGD EMVs induced brain injury after IS.

Conclusions

These findings demonstrate that circulating EMVs and EMV-miR-125a-5p are closely related with the occurrence, progress, subtypes and severity of IS, and they can serve as innovative biomarkers and therapeutic targets for IS, especially when they are combined.

Limb Remote Ischemic Conditioning Promotes Neurogenesis after Cerebral Ischemia by Modulating miR-449b/Notch1 Pathway in Mice

Neurogenesis plays an important role in the prognosis of stroke patients and is known to be promoted by the activation of the Notch1 signaling pathway. Studies on the airway epithelium have shown that miR-449b represses the Notch pathway. The study aimed to investigate whether limb remote ischemic conditioning (LRIC) was able to promote neurogenesis in cerebral ischemic mice, and to investigate the role of the miR-449b/Notch1 pathway in LRIC-induced neuroprotection. Male C57BL/6 mice (22–25 g) were subjected to transient middle cerebral artery occlusion (MCAO), and LRIC was performed in the bilateral lower limbs immediately after MCA occlusion. Immunofluorescence staining was performed to assess neurogenesis. The cell line NE-4C was used to elucidate the proliferation of neuronal stem cells in 8% O₂. After LRIC treatment on day 28, mice recovered neurological function. Neuronal precursor proliferation was enhanced in the SVZ, and neuronal precursor migration was enhanced in the basal ganglia on day 7. LRIC promoted the improvement of neurological function in mice on day 28, promoted neuronal precursor proliferation in the SVZ, and enhanced neuronal precursor migration in the basal ganglia on day 7. The neurological function score was negatively correlated with the number of BrdU-positive/DCX-positive cells in the SVZ and striatum. LRIC promoted activated Notch1 protein expression in the SVZ and substantially downregulated miR-449b levels in the SVZ and plasma. In vitro, miR-449b was found to target Notch1. Lentivirus-mediated miR-449b knockdown increased Notch1 levels in NE-4C cells and increased proliferation in the cells. The effects of miR-449b inhibition on neurogenesis were ablated by the application of Notch1 shRNA. Our study showed that LRIC promoted the proliferation and migration of neural stem cells after MCAO, and these effects were modulated by the miR-449b/Notch1 pathway.

Salivary miRNA Expression in Children With Persistent Post-concussive Symptoms

Background

Up to one-third of concussed children develop persistent post-concussive symptoms (PPCS). The identification of biomarkers such as salivary miRNAs that detect concussed children at increased risk of PPCS has received growing attention in recent years. However, whether and how salivary miRNA expression levels differ over time between concussed children with and without PPCS is unknown.

Aim

To identify salivary MicroRNAs (miRNAs) whose expression levels differ over time post-concussion in children with vs. without PPCS.

Methods

We conducted a prospective cohort study with saliva collection at up to three timepoints: (1) within one week of injury; (2) one to two weeks post-injury; and (3) 4-weeks post-injury. Participants were children (ages 11 to 17 years) with a physician-diagnosed concussion from a single hospital center. We collected participants' daily post-concussion symptom ratings throughout their enrollment using the Post-concussion Symptom Scale, and defined PPCS as a total symptom score of ≥ 5 at 28 days post-concussion. We extracted salivary RNA from the saliva samples and measured expression levels of 827 salivary miRNAs. We then compared the longitudinal expression levels of salivary miRNAs in children with vs. without PPCS using linear models with repeated measures.

Results

A total of 135 saliva samples were collected from 60 children. Of the 827 miRNAs analyzed, 91 had expression levels above the calculated background threshold and were included in the differential gene expression analyses. Of these 91 miRNAs, 13 had expression levels that differed significantly across the three timepoints post-concussion between children with and without PPCS (i.e., hsa-miR-95-3p, hsa-miR-301a-5p, hsa-miR-626, hsa-miR-548y, hsa-miR-203a-5p, hsa-miR-548e-5p, hsa-miR-585-3p, hsa-miR-378h, hsa-miR-1323, hsa-miR-183-5p, hsa-miR-200a-3p, hsa-miR-888-5p, hsa-miR-199a-3p+hsa-miR-199b-3p). Among these 13 miRNAs, one (i.e., hsa-miR-203a-5p) was also identified in a prior study, with significantly different expression levels between children with and without PPCS.

Conclusion

Our results from the longitudinal assessment of miRNAs indicate that the expression levels of 13 salivary miRNAs differ over time post-injury in concussed children with vs. without PPCS. Salivary miRNAs may be a promising biomarker for PPCS in children, although replication studies are needed.

Crosstalk of Astrocytes and Other Cells during Ischemic Stroke

Stroke is a leading cause of death and long-term disability worldwide. Astrocytes structurally compose tripartite synapses, blood–brain barrier, and the neurovascular unit and perform multiple functions through cell-to-cell signaling of neurons, glial cells, and vasculature. The crosstalk of astrocytes and other cells is complicated and incompletely understood. Here we review the role of astrocytes in response to ischemic stroke, both beneficial and detrimental, from a cell–cell interaction perspective. Reactive astrocytes provide neuroprotection through antioxidation and antiexcitatory effects and metabolic support; they also contribute to neurorestoration involving neurogenesis, synaptogenesis, angiogenesis, and oligodendrogenesis by crosstalk with stem cells and cell lineage. In the meantime, reactive astrocytes also play a vital role in neuroinflammation and brain edema. Glial scar formation in the chronic phase hinders functional recovery. We further discuss astrocyte enriched microRNAs and exosomes in the regulation of ischemic stroke. In addition, the latest notion of reactive astrocyte subsets and astrocytic activity revealed by optogenetics is mentioned. This review discusses the current understanding of the intimate molecular conversation between astrocytes and other cells and outlines its potential implications after ischemic stroke. “Neurocentric” strategies may not be sufficient for neurological protection and recovery; future therapeutic strategies could target reactive astrocytes.

miR‑30e‑5p attenuates neuronal deficit and inflammation of rats with intracerebral hemorrhage by regulating TLR4

microRNAs (miRNAs or miRs) have been reported to regulate the pathology of intracerebral hemorrhage (ICH). Therefore, the present study aimed to investigate the function of miR-30e-5p in rats with ICH with specific focus on Toll-like receptor (TLR)4. In the present study, collagenase type IV was used for the establishment of the ICH model in rats, prior to which the rats were injected with miR-30e-5p mimic or miR-30e-5p mimic + pcDNA3.1-TLR4 plasmid. The expression levels of miR-30e-5p and TLR4 were then measured using reverse transcription-quantitative PCR and western blotting. The potential interaction between miR-30e-5p and TLR4 was tested using the MicroRNA Target Prediction Database and dual-luciferase reporter and RNA immunoprecipitation assay. In addition, the concentration of TNF-α, IL-6 and IL-1β was measured using ELISA. The protein expression levels of TLR4/myeloid differentiation factor 88 (MyD88)/TIR-domain-containing adapter-inducing interferon-β (TRIF) signaling-associated molecules were measured by western blotting. Following induction of ICH, miR-30e-5p expression was downregulated, while TLR4 expression was upregulated. By contrast, injection with miR-30e-5p mimic rescued neuronal function while suppressing neuronal inflammation in rats following ICH; these effects were reversed by co-overexpression of TLR4. Furthermore, overexpression of miR-30e-5p inactivated TLR4/MyD88/TRIF signaling in rats with ICH; this was also reversed by overexpression of TLR4. Taken together, these results suggested that overexpression of miR-30e-5p exerted a protective role against neuronal deficit and inflammation caused by ICH in rats by targeting TLR4 and inactivating TLR4/MyD88/TRIF signaling.

S1PR3, as a Core Protein Related to Ischemic Stroke, is Involved in the Regulation of Blood–Brain Barrier Damage

Background: Ischemic stroke is the most common stroke incident. Sphingosine-1-phosphate (S1P) receptor 3 (S1PR3) is a member of the downstream G protein-coupled receptor family of S1P. The effect of S1PR3 on ischemic stroke remains elusive.

Methods: We downloaded two middle cerebral artery occlusion (MCAO) microarray datasets from the Gene Expression Omnibus (GEO) database and screened differentially expressed genes (DEGs). Then, we performed a weighted gene coexpression network analysis (WGCNA) and identified the core module genes related to ischemic stroke. We constructed a protein–protein interaction (PPI) network for the core genes in which DEGs and WGCNA intersected. Finally, we discovered that S1PR3 was involved as the main member of the red proteome. Then, we explored the mechanism of S1PR3 in the mouse tMCAO model. The S1PR3-specific inhibitor CAY10444 was injected into the abdominal cavity of mice after cerebral ischemia/reperfusion (I/R) injury, and changes in the expression of blood–brain barrier-related molecules were measured using PCR, western blotting, and immunofluorescence staining.

Results: Both GEO datasets showed that S1PR3 was upregulated during cerebral I/R in mice. WGCNA revealed that the light yellow module had the strongest correlation with the occurrence of IS. We determined the overlap with DEGs, identified 146 core genes that are potentially related to IS, and constructed a PPI network. Finally, S1PR3 was found to be the main member of the red proteome. In the mouse cerebral I/R model, S1PR3 expression increased 24 h after ischemia. After the administration of CAY10444, brain edema and neurological deficits in mice were ameliorated. CAY10444 rescued the decreased expression of the tight junction (TJ) proteins zonula occludens 1 (ZO1) and occludin after ischemia induced by transient MCAO (tMCAO) and reduced the increase in aquaporin 4 (AQP4) levels after tMCAO, preserving the integrity of the BBB. Finally, we found that S1PR3 is involved in regulating the mitogen-activated protein kinase (MAPK) and (phosphatidylinositol-3 kinase/serine-threonine kinase) PI3K-Akt signaling pathways.

Conclusion: S1PR3 participates in the regulation of blood–brain barrier damage after cerebral I/R. S1PR3 is expected to be an indicator and predictor of cerebral ischemia, and drugs targeting S1PR3 may also provide new ideas for clinical medications.

The Role of miRNAs in Dexmedetomidine's Neuroprotective Effects against Brain Disorders

There are limited neuroprotective strategies for various central nervous system conditions in which fast and sustained management is essential. Neuroprotection-based therapeutics have become an intensively researched topic in the neuroscience field, with multiple novel promising agents, from natural products to mesenchymal stem cells, homing peptides, and nanoparticles-mediated agents, all aiming to significantly provide neuroprotection in experimental and clinical studies. Dexmedetomidine (DEX), an α2 agonist commonly used as an anesthetic adjuvant for sedation and as an opioid-sparing medication, stands out in this context due to its well-established neuroprotective effects. Emerging evidence from preclinical and clinical studies suggested that DEX could be used to protect against cerebral ischemia, traumatic brain injury (TBI), spinal cord injury, neurodegenerative diseases, and postoperative cognitive disorders. MicroRNAs (miRNAs) regulate gene expression at a post-transcriptional level, inhibiting the translation of mRNA into functional proteins. In vivo and in vitro studies deciphered brain-related miRNAs and dysregulated miRNA profiles after several brain disorders, including TBI, ischemic stroke, Alzheimer’s disease, and multiple sclerosis, providing emerging new perspectives in neuroprotective therapy by modulating these miRNAs. Experimental studies revealed that some of the neuroprotective effects of DEX are mediated by various miRNAs, counteracting multiple mechanisms in several disease models, such as lipopolysaccharides induced neuroinflammation, β-amyloid induced dysfunction, brain ischemic-reperfusion injury, and anesthesia-induced neurotoxicity models. This review aims to outline the neuroprotective mechanisms of DEX in brain disorders by modulating miRNAs. We address the neuroprotective effects of DEX by targeting miRNAs in modulating ischemic brain injury, ameliorating the neurotoxicity of anesthetics, reducing postoperative cognitive dysfunction, and improving the effects of neurodegenerative diseases.

The Role of miR-20 in Health and Disease of the Central Nervous System

Current understanding of the mechanisms underlying central nervous system (CNS) injury is limited, and traditional therapeutic methods lack a molecular approach either to prevent acute phase or secondary damage, or to support restorative mechanisms in the nervous tissue. microRNAs (miRNAs) are endogenous, non-coding RNA molecules that have recently been discovered as fundamental and post-transcriptional regulators of gene expression. The capacity of microRNAs to regulate the cell state and function through post-transcriptionally silencing hundreds of genes are being acknowledged as an important factor in the pathophysiology of both acute and chronic CNS injuries. In this study, we have summarized the knowledge concerning the pathophysiology of several neurological disorders, and the role of most canonical miRNAs in their development. We have focused on the miR-20, the miR-17~92 family to which miR-20 belongs, and their function in the normal development and disease of the CNS.

Long Noncoding RNA TUG1 Aggravates Cerebral Ischemia/Reperfusion Injury by Acting as a ceRNA for miR-3072-3p to Target St8sia2

Long noncoding RNA taurine-upregulated gene 1 (TUG1) is considered to be involved in postischemic cerebral inflammation, whereas polysialic acid (polySia, PSA), the product of St8sia2, constitutes polysialylated neural adhesion cell molecule (PSA-NCAM) in both mice and humans and that cerebral PSA-NCAM level is elevated in neuronal progenitor cells in response to transient focal ischemia. Herein, we aim to identify novel miRNAs that bridge the functions of St8sia2 and TUG1 in ischemia-associated injuries. In both in vivo (C57BL/6J mouse ischemia/reperfusion, I/R model) and in vitro (mouse neuroblastoma N2A cell oxygen glucose deprivation/reoxygenation, OGD model) settings, we observed upregulated TUG1 and St8sia2 after the induction of ischemic injury, accompanied by reduced miR-3072-3p expression. We performed siRNA-induced TUG1 knockdown combined with the induction of ischemic injury; the results showed that inhibiting TUG1 expression led to the reduced infarct area and improved neurological deficit. Through bioinformatics analysis, miR-3072-3p was found to target both St8sia2 and TUG1, which was subsequently verified by the luciferase reporter system and RNA binding protein immunoprecipitation assay. Also, the addition of miR-3072-3p mimic/inhibitor resulted in reduced/elevated St8sia2 expression at the protein level. Further studies revealed that in both in vivo and in vitro settings, TUG1 bound competitively to miR-3072-3p to regulate St8sia2 expression and promote apoptosis. In summary, targeting the TUG1/miR-3072-3p/St8sia2 regulatory cascade, a novel cascade we identified in cerebral ischemia injury, may render feasible therapeutic possibilities for overcoming cerebral ischemic insults.

Inhibiting Sphingosine 1-Phosphate Receptor Subtype 3 Attenuates Brain Damage During Ischemia-Reperfusion Injury by Regulating nNOS/NO and Oxidative Stress

Background

Ischemic stroke (IS) is a common disease endangering human life and health. Cerebral ischemia triggers a series of complex harmful events, including excitotoxicity, inflammation and cell death, as well as increased nitric oxide production through the activation of nitric oxide synthase (NOS). Oxidative stress plays a major role in cerebral ischemia and reperfusion. Sphingosine 1-phosphate receptor subtype 3 (S1PR3), a member of S1P’s G protein-coupled receptors S1PR1-S1PR5, is involved in a variety of biological effects in the body, and its role in regulating oxidative stress during cerebral ischemia and reperfusion is still unclear.

Methods

Transient middle cerebral artery occlusion (tMCAO) mice were selected as the brain ischemia–reperfusion (I/R) injury model. Male C57/BL6 mice were treated with or without a selective S1PR3 inhibition after tMCAO, and changes in infarct volume, Nissl staining, hematoxylin-eosin (H&E) staining and NOS protein, nitric oxide (NO), superoxide dismutase (SOD), and malondialdehyde (MDA) content after tMCAO were observed.

Results

In the cerebral ischemia–reperfusion model, inhibition of S1PR3 improved the infarct volume and neuronal damage in mice after tMCAO. Similarly, inhibition of S1PR3 can reduce the expression of NO synthase subtype neuronal NOS (nNOS) and reduce the production of NO after cerebral ischemia. After cerebral ischemia and reperfusion, the oxidative stress response was enhanced, and after the administration of the S1PR3 inhibitor, the SOD content increased and the MDA content decreased, indicating that S1PR3 plays an important role in regulating oxidative stress response.

Conclusion

Inhibiting S1PR3 attenuates brain damage during I/R injury by regulating nNOS/NO and oxidative stress, which provides a potential new therapeutic target and mechanism for the clinical treatment of IS.

miR-197 Participates in Lipopolysaccharide-Induced Cardiomyocyte Injury by Modulating SIRT1

Sepsis is a systemic inflammation and is capable of inducing myocarditis, which is a major leading cause of death in patients. Studies have found that miR-197 is correlated with the prognosis of patients with inflammatory heart disease, but its effect on sepsis-induced cardiomyocyte injury remains unclear. We treated H9c2 cells with lipopolysaccharide (LPS), then detected the cell viability via the cell counting kit-8 (CCK-8) assay and quantified miR-197 expression via quantitative real-time polymerase chain reaction (qRT-PCR). Then, we investigated the role of miR-197 in LPS-induced H9c2 cells by CCK-8 assay, flow cytometry, lactate dehydrogenase (LDH) measurement, enzyme-linked immunosorbent assay (ELISA), qRT-PCR, and western blot. Subsequently, silent information regulator 1 (SIRT1) was downregulated in H9c2 cells to explore its interaction with miR-197 under LPS induction. LPS induced miR-197 overexpression in H9c2 cells. LPS restrained viability, the expressions of B-cell lymphoma-2 (Bcl-2) and SIRT1, but promoted apoptosis, LDH release, and levels of interleukin-6 (IL-6), interleukin-1β (IL-1β), acetyl (AC)-p53, BCL2-associated X (Bax), and cleaved caspase-3 in H9c2 cells. miR-197 inhibition reversed the effects of LPS on H9c2 cells. The protective role of miR-197 downregulation in LPS-induced H9c2 cells was reversed by SIRT1 silencing. miR-197 contributed to LPS-induced cardiomyocyte injury by modulating SIRT1, which might be used as a molecular marker in the management of sepsis.

Changes in circulating microRNAs following head impacts in soccer

AIM

To explore the short-term effects of accidental head impacts and repetitive headers on circulating microRNAs, accounting for the effects of high-intensity exercise alone.

METHODS

Blood samples were collected from professional soccer players at rest. Repeat samples were drawn 1 h and 12 h after three conditions: (1) accidental head impacts in a match, (2) repetitive headers during training, and (3) high-intensity exercise. 89 samples were screened to detect microRNAs expressed after each exposure. Identified microRNAs were then validated in 98 samples to determine consistently deregulated microRNAs. Deregulated microRNAs were further explored using bioinformatics to identify target genes and characterize their involvement in biological pathways.

RESULTS

Accidental head impacts led to deregulation of eight microRNAs that were unaffected by high-intensity exercise; target genes were linked to 12 specific signaling pathways, primarily regulating chromatin organization, Hedgehog and Wnt signaling. Repetitive headers led to deregulation of six microRNAs that were unaffected by high-intensity exercise; target genes were linked to one specific signaling pathway (TGF-β). High-intensity exercise led to deregulation of seven microRNAs; target genes were linked to 31 specific signaling pathways.

CONCLUSION

We identified microRNAs specific to accidental head impacts and repetitive headers in soccer, potentially being useful as brain injury biomarkers.

MiR-107 Aggravates Oxygen-Glucose Deprivation/Reoxygenation (OGD/R)-Induced Injury Through Inactivating PI3K-AKT Signalling Pathway by Targeting FGF9/FGF12 in PC12 Cells

OBJECTIVES

The aberrant expression of miR-107 has been confirmed in some neurological diseases, including ischemic stroke (IS). However, the function of miR-107 and underlying mechanisms are ambiguous.

MATERIALS AND METHODS

Oxygen-Glucose Deprivation/Reoxygenation (OGD/R)-induced PC12 cells were used to mimic IS condition. MiR-107 expression and differentially expressed genes (DEGs) responding to IS were analyzed by GSE97532 and GSE61616 datasets, respectively. The target genes of miR-107 were predicted by TargetScan and confirmed by dual-luciferase reporter assay. Cell counting kit-8 and apoptosis assays were conducted to explore the role of miR-107 in biological behaviors of OGD/R-induced PC12 cells.

RESULTS

Bioinformatics analysis revealed that miR-107 expression was elevated in rats with middle cerebral artery occlusion (MCAO), which was confirmed in OGD/R-treated PC12 cells. Notably, miR-107 strongly inhibited the proliferation of OGD/R-treated PC12 cells. As most DEGs were enriched in PI3K-AKT signaling pathway, which was critical for IS, DEGs in this pathway was compared with the down-regulated genes and the predicted genes to obtain potential target genes of miR-107, and ultimately fibroblast growth factor (FGF)9 and FGF12 stood out. The experiments demonstrated that miR-107 inhibited viability and promoted apoptosis of OGD/R-treated PC12 cells by down-regulating FGF9/FGF12 level. Mechanically, for the first time, we clarified the mechanism via which miR-107 inactivated PI3K-AKT signaling pathway by targeting FGF9/FGF12.

CONCLUSIONS

We summarized that miR-107 aggravates OGD/R-induced injury through inactivating PI3K-AKT signaling pathway via targeting FGF9/FGF12. Therefore, our study elucidates the neurotoxicity of miR-107 in IS development and provides a new promising therapy strategy for IS.

Expression Profile of miRs in Mesial Temporal Lobe Epilepsy: Systematic Review

Temporal lobe epilepsy (TLE) is one of the most common forms of focal epilepsy in children and adults. TLE is characterized by variable onset and seizures. Moreover, this form of epilepsy is often resistant to pharmacotherapy. The search for new mechanisms for the development of TLE may provide us with a key to the development of new diagnostic methods and a personalized approach to the treatment. In recent years, the role of non-coding ribonucleic acids (RNA) has been actively studied, among which microRNA (miR) is of the greatest interest. (1) Background: The purpose of the systematic review is to analyze the studies carried out on the role of miRs in the development of mesial TLE (mTLE) and update the existing knowledge about the biomarkers of this disease. (2) Methods: The search for publications was carried out in the databases PubMed, Springer, Web of Science, Clinicalkeys, Scopus, OxfordPress, Cochrane. The search was carried out using keywords and combinations. We analyzed publications for 2016–2021, including original studies in an animal model of TLE and with the participation of patients with TLE, thematic and systemic reviews, and Cochrane reviews. (3) Results: this thematic review showed that miR‒155, miR‒153, miR‒361‒5p, miR‒4668‒5p, miR‒8071, miR‒197‒5p, miR‒145, miR‒181, miR‒199a, miR‒1183, miR‒129‒2‒3p, miR‒143‒3p (upregulation), miR–134, miR‒0067835, and miR‒153 (downregulation) can be considered as biomarkers of mTLE. However, the roles of miR‒146a, miR‒142, miR‒106b, and miR‒223 are questionable and need further study. (4) Conclusion: In the future, it will be possible to consider previously studied miRs, which have high specificity and sensitivity in mTLE, as prognostic biomarkers (predictors) of the risk of developing this disease in patients with potentially epileptogenic structural damage to the mesial regions of the temporal lobe of the brain (congenital disorders of the neuronal migration and neurogenesis, brain injury, neuro-inflammation, tumor, impaired blood supply, neurodegeneration, etc.).

Transient Focal Cerebral Ischemia Leads to miRNA Alterations in Different Brain Regions, Blood Serum, Liver, and Spleen

Ischemic stroke is characterized by an occlusion of a cerebral blood vessel resulting in neuronal cell death due to nutritional and oxygen deficiency. Additionally, post-ischemic cell death is augmented after reperfusion. These events are paralleled by dysregulated miRNA expression profiles in the peri-infarct area. Understanding the underlying molecular mechanism in the peri-infarct region is crucial for developing promising therapeutics. Utilizing a tMCAo (transient Middle Cerebral Artery occlusion) model in rats, we studied the expression levels of the miRNAs (miR) 223-3p, 155-5p, 3473, and 448-5p in the cortex, amygdala, thalamus, and hippocampus of both the ipsi- and contralateral hemispheres. Additionally, the levels in the blood serum, spleen, and liver and the expression of their target genes, namely, Nlrp3, Socs1, Socs3, and Vegfa, were assessed. We observed an increase in all miRNAs on the ipsilateral side of the cerebral cortex in a time-dependent manner and increased miRNAs levels (miR-223-3p, miR-3473, and miR-448-5p) in the contralateral hemisphere after 72 h. Besides the cerebral cortex, the amygdala presented increased expression levels, whereas the thalamus and hippocampus showed no alterations. Different levels of the investigated miRNAs were detected in blood serum, liver, and spleen. The gene targets were altered not only in the peri-infarct area of the cortex but selectively increased in the investigated non-affected brain regions along with the spleen and liver during the reperfusion time up to 72 h. Our results suggest a supra-regional influence of miRNAs following ischemic stroke, which should be studied to further identify whether miRNAs are transported or locally upregulated.

Immune Modulation as a Key Mechanism for the Protective Effects of Remote Ischemic Conditioning After Stroke

Remote ischemic conditioning (RIC), which involves a series of short cycles of ischemia in an organ remote to the brain (typically the limbs), has been shown to protect the ischemic penumbra after stroke and reduce ischemia/reperfusion (IR) injury. Although the exact mechanism by which this protective signal is transferred from the remote site to the brain remains unclear, preclinical studies suggest that the mechanisms of RIC involve a combination of circulating humoral factors and neuronal signals. An improved understanding of these mechanisms will facilitate translation to more effective treatment strategies in clinical settings. In this review, we will discuss potential protective mechanisms in the brain and cerebral vasculature associated with RIC. We will discuss a putative role of the immune system and circulating mediators of inflammation in these protective processes, including the expression of pro-and anti-inflammatory genes in peripheral immune cells that may influence the outcome. We will also review the potential role of extracellular vesicles (EVs), biological vectors capable of delivering cell-specific cargo such as proteins and miRNAs to cells, in modulating the protective effects of RIC in the brain and vasculature.

Hemorrhagic Stroke Induces a Time-Dependent Upregulation of miR-150-5p and miR-181b-5p in the Bloodstream

To date, the only effective pharmacological treatment for ischemic stroke is limited to the clinical use of recombinant tissue plasminogen activator (rtPA), although endovascular therapy has also emerged as an effective treatment for acute ischemic stroke. Unfortunately, the benefit of this treatment is limited to a 4.5-h time window. Most importantly, the use of rtPA is contraindicated in the case of hemorrhagic stroke. Therefore, the identification of a reliable biomarker to distinguish hemorrhagic from ischemic stroke could provide several advantages, including an earlier diagnosis, a better treatment, and a faster decision on ruling out hemorrhage so that tPA may be administered earlier. microRNAs (miRNAs) are stable non-coding RNAs crucially involved in the downregulation of gene expression via mRNA cleavage or translational repression. In the present paper, taking advantage of three preclinical animal models of stroke, we compared the miRNA blood levels of animals subjected to permanent or transient middle cerebral artery occlusion (MCAO) or to collagenase-induced hemorrhagic stroke. Preliminarily, we examined the rat miRNome in the brain tissue of ischemic and sham-operated rats; then, we selected those miRNAs whose expression was significantly modulated after stroke to create a list of miRNAs potentially involved in stroke damage. These selected miRNAs were then evaluated at different time intervals in the blood of rats subjected to permanent or transient focal ischemia or to hemorrhagic stroke. We found that four miRNAs-miR-16-5p, miR-101a-3p, miR-218-5p, and miR-27b-3p-were significantly upregulated in the plasma of rats 3 h after permanent MCAO, whereas four other different miRNAs-miR-150-5p, let-7b-5p, let-7c-5p, and miR-181b-5p-were selectively upregulated by collagenase-induced hemorrhagic stroke. Collectively, our study identified some selective miRNAs expressed in the plasma of hemorrhagic rats and pointed out the importance of a precise time point measurement to render more reliable the use of miRNAs as stroke biomarkers.

Sevoflurane-Induced miR-211-5p Promotes Neuronal Apoptosis by Inhibiting Efemp2

Sevoflurane exposure can result in serious neurological side effects including neuronal apoptosis and cognitive impairment. Although the microRNA miR-211-5p is profoundly upregulated following sevoflurane exposure in neonatal rodent models, the impact of miR-211-5p on neuronal apoptosis and cognitive impairment postsevoflurane exposure has not yet been elucidated. Here, we found that sevoflurane upregulated miR-211-5p and downregulated EGF-Containing Fibulin Extracellular Matrix Protein 2 (Efemp2, Fibulin-4) levels in vitro and in vivo. Sevoflurane's effect on miR-211-5p expression was based on enhancing primary miR-211 transcription. miR-211-5p targets Efemp2's mRNA 3′-untranslated region, reducing Efemp2 expression. RNA immunoprecipitation revealed significant enrichment of the miR-211-5p:Efemp2 mRNA dyad in the RNA-induced silencing complex. miR-211-5p mimics downregulated Efemp2, leading to phosphorylation of Smad2 and Smad3, upregulation of pro-apoptotic Bim, and mitochondrial release of allograft inflammatory factor 1 and cytochrome C. In contrast, miR-211-5p hairpin inhibitor (AntimiR-211-5p) negatively regulated this apoptotic pathway and reduced neuronal apoptosis in an Efemp2-dependent manner. Sevoflurane-exposed mice administered AntimiR-211-5p displayed reduced cortical apoptosis levels and near-term cognitive impairment. In conclusion, sevoflurane-induced miR-211-5p promotes neuronal apoptosis via Efemp2 inhibition. Summary statement: This study revealed the significance of sevoflurane-induced increases in miR-211-5p on the promotion of neuronal apoptosis via inhibition of Efemp2 and its downstream targets.

Comprehensive Analysis of Potential miRNA-Target mRNA-Immunocyte Subtype Network in Cerebral Infarction

INTRODUCTION

Cerebral infarction (CI) is one of the leading causes of serious long-term disability and mortality.

OBJECTIVE

We aimed to identify potential miRNAs and target mRNAs and assess the involvement of immunocyte infiltration in the process of CI.

METHODS

First, miRNA and mRNA data were downloaded from the Gene Expression Omnibus database, followed by differential expression analysis. Second, correlation analysis between differentially expressed mRNAs and differential immunocyte subtypes was performed through the CIBERSORT algorithm. Third, the regulatory network between miRNAs and immunocyte subtype-related mRNAs was constructed followed by the functional analysis of these target mRNAs. Fourth, correlation validation between differentially expressed mRNAs and differential immunocyte subtypes was performed in the GSE37587 dataset. Finally, the diagnostic ability of immunocyte subtype-related mRNAs was tested.

RESULTS

Up to 17 differentially expressed miRNAs and 3,267 differentially expressed mRNAs were identified, among which 310 differentially expressed mRNAs were significantly associated with immunocyte subtypes. Several miRNA-target mRNA-immunocyte subtype networks including hsa-miR-671-3p-ZC3HC1-neutrophils, hsa-miR-625-CD5-monocytes, hsa-miR-122-ACOX1/DUSP1/NEDD9-neutrophils, hsa-miR-455-5p-SLC24A4-monocytes, and hsa-miR-455-5p-SORL1-neutrophils were identified. LAT, ACOX1, DUSP1, NEDD9, ZC3HC1, BIN1, AKT1, DNMT1, SLC24A4, and SORL1 had a potential diagnostic value for CI.

CONCLUSIONS

The network including miRNA, target mRNA, and immunocyte subtype may be novel regulators and diagnostic and therapeutic targets in CI.