MiRNA: Involvement of the MAPK Pathway in Ischemic Stroke. A Promising Therapeutic Target

MicroRNA-124a promoted the differentiation of bone marrow mesenchymal stem cells into neurons through Notch signal pathway

This study investigated the possible mechanisms of microRNA-124a on the differentiation of bone marrow mesenchymal stem cells (BMSCs) and its underlying mechanism. β-Thiol ethanol induced Notch1 mRNA expression, microRNA-124a inhibitor reduced the effects of β-thiol ethanol on Notch1 mRNA expression in BMSCs. Baicalin induced Hes1 mRNA expression, and microRNA-124a inhibitor reduced the effects of baicalin on Hes1 mRNA expression in BMSCs. Si-Notch1 suppressed Hes1 mRNA expression in BMSCs. Baicalin increased the effects of Notch1 on Hes1 mRNA expression in BMSCs. Si-Notch1 increased cell growth of BMSCs. Baicalin reduced the effects of si-Notch1 on cell growth and the differentiation of BMSCs. We demonstrated that microRNA-124a promoted the differentiation of BMSCs into neurons through Notch/Hes1 signal pathway.

LncRNA NPTN-IT1-201 Ameliorates Depressive-like Behavior by Targeting miR-142-5p and Regulating Inflammation and Apoptosis via BDNF

OBJECTIVE

Long noncoding RNAs (lncRNAs) and microRNAs (miRNAs) are widely expressed in the brain and are associated with the development of neurological and neurodegenerative diseases. However, their roles and molecular mechanisms in major depressive disorder (MDD) remain largely unknown. This study aimed to identify lncRNAs and miRNAs involved in the development of MDD and elucidate their molecular mechanisms.

METHODS

Transcriptome and bioinformatic analyses were performed to identify miRNAs and lncRNAs related to MDD. C57 mice were subjected to chronic unpredictable mild stress (CUMS) to establish a depression model. Lentiviruses containing either lncRNA NPTN-IT1-201 or miR-142-5p were microinjected into the hippocampal region of these mice. Behavioral tests including the sucrose preference test (SPT), tail suspension test (TST), and forced swim test (FST) were conducted to evaluate depressive-like behaviors.

RESULTS

The results revealed that overexpression of lncRNA NPTN-IT1-201 or inhibition of miR-142-5p significantly ameliorated depressive-like behaviors in CUMS-treated mice. Dual-luciferase reporter assays confirmed interactions between miR-142-5p with both brain-derived neurotrophic factor (BDNF) and NPTN-IT1-201. ELISA analysis revealed significant alterations in relevant biomarkers in the blood samples of MDD patients compared to healthy controls. Histological analyses, including HE and Nissl staining, showed marked structural changes in brain tissues following CUMS treatment, which were partially reversed by lncRNA NPTN-IT1-201 overexpression or miR-142-5p inhibition. Immunofluorescence imaging demonstrated significant differences in the levels of BAX, Bcl2, p65, Iba1 among different treatment groups. TUNEL assays confirmed reduced apoptosis in brain tissues following these interventions. Western blotting showed the significant differences in BDNF, BAX, and Bcl2 protein levels among different treatment groups.

CONCLUSION

NPTN-IT1-201 regulates inflammation and apoptosis in MDD by targeting BDNF via miR-142-5p, making it a potential therapeutic target for MDD.

Up-regulation of miR-126 via DNA methylation in hypoxia-preconditioned endothelial cells may contribute to hypoxic tolerance of neuronal cells

BACKGROUND

Endothelial cells (ECs) can confer neuroprotection by secreting molecules. This study aimed to investigate whether DNA methylation contributes to the neuroprotective gene expression induced by hypoxia preconditioning (HPC) in ECs and to clarify that the secretion of molecules from HPC ECs may be one of the molecular mechanisms of neuroprotection.

METHODS

Human microvascular endothelial cell-1 (HMEC-1) was cultured under normal conditions (C), hypoxia(H), and hypoxia preconditioning (HPC), followed by the isolation of culture medium (CM). SY5Y cell incubated with the isolated CM from HMEC-1 was exposed to oxygen-glucose deprivation (OGD). The DNA methyltransferases (DNMTs), global methylation level, miR-126 and its promotor DNA methylation level in HMEC-1 were measured. The cell viability and cell injury in SY5Y were detected.

RESULTS

HPC decreased DNMTs level and global methylation level as well as increased miR-126 expression in HMEC-1. CM from HPC treated HMEC-1 also relieved SY5Y cell damage, while CM from HMEC-1 which over-expression of miR-126 can reduce injury in SY5Y under OGD condition.

CONCLUSIONS

These findings indicate EC may secrete molecules, such as miR-126, to execute neuroprotection induced by HPC through regulating the expression of DNMTs.

In vivo protective effects of 6‑gingerol in cerebral ischemia involve preservation of antioxidant defenses and activation of anti‑apoptotic pathways

Stroke is an important medical problem in developing countries, characterized by a sudden disruption of blood supply to the brain, either through occlusion or hemorrhage. It is a major cause of neurological impairment, resulting in high medical costs. The present study examined the effect of 6-gingerol on morphological changes, antioxidant defenses, and the anti-apoptotic factors p38 mitogen-activated protein kinase (MAPK) and mitofusin (Mfn)2, in a rat model of focal cerebral ischemia. A total of 60 healthy male Wistar rats were randomly allocated into six groups: Control, right middle cerebral artery occlusion (Rt.MCAO) + vehicle, Rt.MCAO + piracetam, and Rt.MCAO + 6-Gin 5, 10 and 20 mg/kg BW groups. The results indicated that 6-gingerol treatment for a duration of 7 days reverses morphological alterations, enhances catalase and glutathione peroxidase activities, reduces Bax, caspase-3 and MAPK expression, and increases Bcl-xL and Mfn2 expression in the cortex and hippocampus. In conclusion, 6-gingerol demonstrated significant in vivo effectiveness in mitigating pathological changes induced by cerebral ischemia. This beneficial effect is attributed, at least in part, to preservation of antioxidant defenses and activation of anti-apoptotic pathways.

The phosphokinase activity of IRE1ɑ prevents the oxidative stress injury through miR-25/Nox4 pathway after ICH

BACKGROUND

Endoplasmic reticulum (ER) stress and oxidative stress are the major pathologies encountered after intracerebral hemorrhage (ICH). Inositol-requiring enzyme-1 alpha (IRE1α) is the most evolutionarily conserved ER stress sensor, which plays a role in monitoring and responding to the accumulation of unfolded/misfolded proteins in the ER lumen. Recent studies have shown that ER stress is profoundly related to oxidative stress in physiological or pathological conditions. The purpose of this study was to investigate the role of IRE1α in oxidative stress and the potential mechanism.

METHODS

A mouse model of ICH was established by autologous blood injection. The IRE1α phosphokinase inhibitor KIRA6 was administrated intranasally at 1 h after ICH, antagomiR-25 and agomiR-25 were injected intraventricularly at 24 h before ICH. Western blot analysis, RT-qPCR, immunofluorescence staining, hematoma volume, neurobehavioral tests, dihydroethidium (DHE) staining, H2O2 content, brain water content, body weight, Hematoxylin and Eosin (HE) staining, Nissl staining, Morris Water Maze (MWM) and Elevated Plus Maze (EPM) were performed.

RESULTS

Endogenous phosphorylated IRE1α (p-IRE1α), miR-25-3p, and Nox4 were increased in the ICH model. Administration of KIRA6 downregulated miR-25-3p expression, upregulated Nox4 expression, promoted the level of oxidative stress, increased hematoma volume, exacerbated brain edema and neurological deficits, reduced body weight, aggravated spatial learning and memory deficits, and increased anxiety levels. Then antagomiR-25 further upregulated the expression of Nox4, promoted the level of oxidative stress, increased hematoma volume, exacerbated brain edema and neurological deficits, whereas agomiR-25 reversed the effects promoted by KIRA6.

CONCLUSION

The IRE1α phosphokinase activity is involved in the oxidative stress response through miR-25/Nox4 pathway in the mouse ICH brain.

DAE-CFR: detecting microRNA-disease associations using deep autoencoder and combined feature representation

BACKGROUND

MicroRNA (miRNA) has been shown to play a key role in the occurrence and progression of diseases, making uncovering miRNA-disease associations vital for disease prevention and therapy. However, traditional laboratory methods for detecting these associations are slow, strenuous, expensive, and uncertain. Although numerous advanced algorithms have emerged, it is still a challenge to develop more effective methods to explore underlying miRNA-disease associations.

RESULTS

In the study, we designed a novel approach on the basis of deep autoencoder and combined feature representation (DAE-CFR) to predict possible miRNA-disease associations. We began by creating integrated similarity matrices of miRNAs and diseases, performing a logistic function transformation, balancing positive and negative samples with k-means clustering, and constructing training samples. Then, deep autoencoder was used to extract low-dimensional feature from two kinds of feature representations for miRNAs and diseases, namely, original association information-based and similarity information-based. Next, we combined the resulting features for each miRNA-disease pair and used a logistic regression (LR) classifier to infer all unknown miRNA-disease interactions. Under five and tenfold cross-validation (CV) frameworks, DAE-CFR not only outperformed six popular algorithms and nine classifiers, but also demonstrated superior performance on an additional dataset. Furthermore, case studies on three diseases (myocardial infarction, hypertension and stroke) confirmed the validity of DAE-CFR in practice.

CONCLUSIONS

DAE-CFR achieved outstanding performance in predicting miRNA-disease associations and can provide evidence to inform biological experiments and clinical therapy.

MicroRNAs: Key modulators of inflammation-associated diseases

Inflammation is a multifaceted biological and pathophysiological response to injuries, infections, toxins, and inflammatory mechanisms that plays a central role in the progression of various diseases. MicroRNAs (miRNAs) are tiny, 19-25 nucleotides long, non-coding RNAs that regulate gene expression via post-transcriptional repression. In this review, we highlight the recent findings related to the significant roles of miRNAs in regulating various inflammatory cascades and immunological processes in the context of many lifestyle-related diseases such as diabetes, cardiovascular diseases, cancer, etc. We also converse on how miRNAs can have a dual impact on inflammatory responses, suggesting that regulation of their functions for therapeutic purposes may be disease-specific.

Early-Stage Application of Agomir-137 Promotes Locomotor Recovery in a Mouse Model of Motor Cortex Injury

Traumatic brain injury (TBI) is a significant risk factor for neurodegenerative disorders, and patients often experience varying degrees of motor impairment. MiR-137, a broadly conserved and brain-enriched miRNA, is a key regulator in neural development and in various neurological diseases. Following TBI, the expression of miR-137 is dramatically downregulated. However, whether miR-137 is a therapeutic target for TBI still remains unknown. Here, for the first time, we demonstrate that intranasal administration of miR-137 agomir (a mimic) in the early stage (0-7 days) of TBI effectively inhibits glial scar formation and improves neuronal survival, while early-stage administration of miR-137 antagomir (an inhibitor) deteriorates motor impairment. This study elucidates the therapeutic potential of miR-137 mimics in improving locomotor recovery following motor cortex injury.

Long-term iTBS Improves Neural Functional Recovery by Reducing the Inflammatory Response and Inhibiting Neuronal Apoptosis Via miR-34c-5p/p53/Bax Signaling Pathway in Cerebral Ischemic Rats

To investigate intermittent theta-burst stimulation (iTBS) effect on ischemic stroke and the underlying mechanism of neurorehabilitation, we developed an ischemia/reperfusion (I/R) injury model in Sprague-Dawley (SD) rats using the middle cerebral artery occlusion/reperfusion (MCAO/r) method. Next, using different behavioral studies, we compared the improvement of the whole organism with and without iTBS administration for 28 days. We further explored the morphological and molecular biological alterations associated with neuronal apoptosis and neuroinflammation by TTC staining, HE staining, Nissl staining, immunofluorescence staining, ELISA, small RNA sequencing, RT-PCR, and western blot assays. The results showed that iTBS significantly protected against neurological deficits and neurological damage induced by cerebral I/R injury. iTBS also significantly decreased brain infarct volume and increased the number of surviving neurons after 28 days. Additionally, it was observed that iTBS decreased synaptic loss, suppressed activation of astrocytes and M1-polarized microglia, and simultaneously promoted M2-polarized microglial activation. Furthermore, iTBS intervention inhibited neuronal apoptosis and exerted a positive impact on the neuronal microenvironment by reducing neuroinflammation in cerebral I/R injured rats. To further investigate the iTBS mechanism, this study was conducted using small RNA transcriptome sequencing of various groups of peri-infarcted tissues. Bioinformatics analysis and RT-PCR discovered the possible involvement of miR-34c-5p in the mechanism of action. The target genes prediction and detection of dual-luciferase reporter genes confirmed that miR-34c-5p could inhibit neuronal apoptosis in cerebral I/R injured rats by regulating the p53/Bax signaling pathway. We also confirmed by RT-PCR and western blotting that miR-34c-5p inhibited Bax expression. In conclusion, our study supports that iTBS is vital in inhibiting neuronal apoptosis in cerebral I/R injured rats by mediating the miR-34c-5p involvement in regulating the p53/Bax signaling pathway.

Neuroinflammation in Acute Ischemic and Hemorrhagic Stroke

PURPOSE OF REVIEW

This review aims to provide an overview of neuroinflammation in ischemic and hemorrhagic stroke, including recent findings on the mechanisms and cellular players involved in the inflammatory response to brain injury.

RECENT FINDINGS

Neuroinflammation is a crucial process following acute ischemic stroke (AIS) and hemorrhagic stroke (HS). In AIS, neuroinflammation is initiated within minutes of the ischemia onset and continues for several days. In HS, neuroinflammation is initiated by blood byproducts in the subarachnoid space and/or brain parenchyma. In both cases, neuroinflammation is characterized by the activation of resident immune cells, such as microglia and astrocytes, and infiltration of peripheral immune cells, leading to the release of pro-inflammatory cytokines, chemokines, and reactive oxygen species. These inflammatory mediators contribute to blood-brain barrier disruption, neuronal damage, and cerebral edema, promoting neuronal apoptosis and impairing neuroplasticity, ultimately exacerbating the neurologic deficit. However, neuroinflammation can also have beneficial effects by clearing cellular debris and promoting tissue repair. The role of neuroinflammation in AIS and ICH is complex and multifaceted, and further research is necessary to develop effective therapies that target this process. Intracerebral hemorrhage (ICH) will be the HS subtype addressed in this review. Neuroinflammation is a significant contributor to brain tissue damage following AIS and HS. Understanding the mechanisms and cellular players involved in neuroinflammation is essential for developing effective therapies to reduce secondary injury and improve stroke outcomes. Recent findings have provided new insights into the pathophysiology of neuroinflammation, highlighting the potential for targeting specific cytokines, chemokines, and glial cells as therapeutic strategies.

Ameliorative effects of 6‑gingerol in cerebral ischemia are mediated via the activation of antioxidant and anti‑inflammatory pathways

Focal ischemia occurs when an embolus or thrombus occludes an artery, causing the rapid obstruction of cerebral blood flow. Although stroke represents a main cause of disability and mortality in developing countries, therapeutic approaches available for this condition remain very limited. The aim of the present study was to examine the effects of the phytochemical, 6-gingerol, on the brain infarct volume, neuronal loss and on the oxidative stress parameters, cyclooxygenase-2 (COX-2) and interleukin (IL)-6, in an animal model of focal ischemic stroke. Male Wistar rats, weighing 250-300 g, were divided into the following six groups: i) The control; ii) right middle cerebral artery occlusion (Rt.MCAO) + vehicle; iii) Rt.MCAO + piracetam; iv) Rt.MCAO + 6-gingerol (6-Gin) at 5 mg/kg body weight (BW); v) Rt.MCAO + 6-Gin at 10 mg/kg BW; and vi) the Rt.MCAO + 6-Gin at 20 mg/kg BW group. The rats in each group received the vehicle or piracetam or 6-gingerol intraperitoneally for 7 days following Rt.MCAO. The brain infarct volume, neuronal loss and alterations in antioxidant and anti-inflammatory levels were assessed in the cortex and hippocampus. The results revealed that the brain infarct volume, malondialdehyde level and the density ratio of COX-2 and IL-6 to β-actin were significantly decreased following treatment with 6-gingerol. In addition, neuronal density and superoxide dismutase activity in the cortex and hippocampus were increased. On the whole, the findings of the present study suggest that 6-gingerol exerts antioxidant and anti-inflammatory effects in vivo, which effectively ameliorate the brain damage induced by focal cerebral ischemic strok.

Pre-ischemic exercise prevents inflammation and apoptosis by inhibiting MAPK pathway in ischemic stroke

Introduction

Mitogen-activated protein kinase (MAPK) pathway is a major mechanism of acute brain damage in ischemic stroke. Pre-ischemic exercise is an effective method to reduce ischemic injury. However, the regulation by pre-ischemic exercise of MAPK pathway and associated mechanisms in animal models remains unclear.

Materials and methods

In this study, Male SD rats were randomly divided into sham group, middle cerebral artery occlusion (MCAO) group, and exercise plus MCAO (EX + MCAO) group for 21 days, and then was established by MCAO. Longa score was used to measure neurological deficits at 0, 1, 2, and 3 days after MCAO. Hematoxylin and eosin staining was used to observe the brain injury. The expression of MAPK pathway was quantified by western blot. The M1 microglia protein was quantified by western blot and immunofluorescence, and the level of inflammatory factor was measured by enzyme-linked immunosorbent assay. TUNEL staining and western blot were used to measure apoptosis.

Results

In the current study, we observed that pre-ischemic exercise effectively decreased infarct volume, neurological deficit score and brain injury in MCAO rats through suppressing the activation of p-JNK and p-ERK1/2. Further investigation revealed that pre-ischemic exercise decreased M1 microglia activation and the serum level of TNF-α and IL-1β. In addition, the increased number of TUNEL-positive cells and Bax/Bcl-2 ratio also were reversed by pre-ischemic exercise.

Conclusions

Pre-ischemic exercise can alleviate inflammatory response and apoptosis by inhibiting the MAPK pathway in MCAO rats.

A systematic review of the research progress of non-coding RNA in neuroinflammation and immune regulation in cerebral infarction/ischemia-reperfusion injury

Cerebral infarction/ischemia-reperfusion injury is currently the disease with the highest mortality and disability rate of cardiovascular disease. Current studies have shown that nerve cells die of ischemia several hours after ischemic stroke, which activates the innate immune response in the brain, promotes the production of neurotoxic substances such as inflammatory cytokines, chemokines, reactive oxygen species and − nitrogen oxide, and mediates the destruction of blood-brain barrier and the occurrence of a series of inflammatory cascade reactions. Meanwhile, the expression of adhesion molecules in cerebral vascular endothelial cells increased, and immune inflammatory cells such as polymorphonuclear neutrophils, lymphocytes and mononuclear macrophages passed through vascular endothelial cells and entered the brain tissue. These cells recognize antigens exposed by the central nervous system in the brain, activate adaptive immune responses, and further mediate secondary neuronal damage, aggravating neurological deficits. In order to reduce the above-mentioned damage, the body induces peripheral immunosuppressive responses through negative feedback, which increases the incidence of post-stroke infection. This process is accompanied by changes in the immune status of the ischemic brain tissue in local and systemic systems. A growing number of studies implicate noncoding RNAs (ncRNAs) as novel epigenetic regulatory elements in the dysfunction of various cell subsets in the neurovascular unit after cerebral infarction/ischemia-reperfusion injury. In particular, recent studies have revealed advances in ncRNA biology that greatly expand the understanding of epigenetic regulation of immune responses and inflammation after cerebral infarction/ischemia-reperfusion injury. Identification of aberrant expression patterns and associated biological effects of ncRNAs in patients revealed their potential as novel biomarkers and therapeutic targets for cerebral infarction/ischemia-reperfusion injury. Therefore, this review systematically presents recent studies on the involvement of ncRNAs in cerebral infarction/ischemia-reperfusion injury and neuroimmune inflammatory cascades, and elucidates the functions and mechanisms of cerebral infarction/ischemia-reperfusion-related ncRNAs, providing new opportunities for the discovery of disease biomarkers and targeted therapy. Furthermore, this review introduces clustered regularly interspaced short palindromic repeats (CRISPR)-Display as a possible transformative tool for studying lncRNAs. In the future, ncRNA is expected to be used as a target for diagnosing cerebral infarction/ischemia-reperfusion injury, judging its prognosis and treatment, thereby significantly improving the prognosis of patients.

Circulating miRNA-195-5p and -451a in Patients with Acute Hemorrhagic Stroke in Emergency Department

(1) Background: In our previous study, acute ischemic stroke (AIS) patients showed increased levels of circulating miRNAs (-195-5p and -451a) involved in vascular endothelial growth factor A (VEGF-A) regulation. Here, we evaluated, for the first time, both circulating miRNAs in acute intracerebral hemorrhagic (ICH) patients. (2) Methods: Circulating miRNAs and serum VEGF-A were assessed by real-time PCR and ELISA in 20 acute ICH, 21 AIS patients, and 21 controls. These were evaluated at hospital admission (T0) and after 96 h (T96) from admission. (3) Results: At T0, circulating miRNAs were five-times up-regulated in AIS patients, tending to decrease at T96. By contrast, in the acute ICH group, circulating miRNAs were significantly increased at both T0 and T96. Moreover, a significant decrease was observed in serum VEGF-A levels at T0 in AIS patients, tending to increase at T96. Conversely, in acute ICH patients, the levels of VEGF-A were significantly decreased at both T0 and T96. (4) Conclusions: The absence of a reduction in circulating miRNAs (195-5p and -451a), reported in acute ICH subjects after 96 h from hospital admission, together with the absence of increment of serum VEGF-A, may represent useful biomarkers indicating the severe brain damage status that characterizes acute ICH patients.

Association of MicroRNAs With Risk of Stroke: A Meta-Analysis

Objectives

Altered expression of microRNAs (miRNAs) may contribute to disease vulnerability. Studies have reported the involvement of miRNA in the pathophysiology of ischemic stroke.

Methods

We performed a meta-analysis of data from 6 studies that used a panel of miRNAs with altered expressions to diagnose ischemic stroke with the Bayesian framework. The I² test and Cochran's Q-statistic were used to assess heterogeneity. Funnel plots were generated and publication bias was assessed using Begg and Egger tests.

Results

On summary receiver operating characteristics (SROC) curve analysis, the pooled sensitivity and specificity of altered miRNA expressions for diagnosis of ischemic stroke was 0.92 (95% confidence interval [CI] 0.80–0.97) and 0.83 (95% CI 0.71–0.90), respectively; the diagnostic odds ratio was 54.35 (95% CI 20.39–144.92), and the area under the SROC curve was 0.93 (95% CI 0.90–0.95).

Conclusions

Our results showed a link between dysregulation of miRNAs and the occurrence of ischemic stroke. Abnormal miRNA expression may be a potential biomarker for ischemic stroke.