Silencing a Multifunctional microRNA Is Beneficial for Stroke Recovery

Inhibition of miR-142-3p promotes intestinal epithelial proliferation and barrier function after ischemia/reperfusion injury by targeting FoxM1

Damage of intestinal barrier function (BF) after ischemia/reperfusion (I/R) injury can induce serious complications and high mortality. MicroRNAs (miRNAs) are involved in intestinal mucosal BF and epithelial proliferation after I/R injury have been reported. We aimed to investigate the role and regulatory mechanism of miR-142-3p (miR-142) in intestinal epithelial proliferation and BF after I/R injury. We detected the proliferation, barrier function and miR-142 expression in clinical ischemic intestinal tissues. Furthermore, we induced an in vivo intestinal I/R injury mouse model and in vitro IEC-6 cells hypoxia/reoxygenation (H/R) injury model. After increasing and decreasing expression of miR-142, we detected the proliferation and barrier function of intestinal epithelial cells after I/R or H/R injury. We found that miR-142 expression was significantly increased in clinical ischemic intestinal mucosa and mouse intestinal mucosa exposed to I/R injury, and there was an inverse relationship between miR-142 and proliferation/BF. Inhibition of miR-142 significant promoted intestinal epithelial proliferation and BF after I/R injury. Furthermore, inhibition of miR-142 improved overall survival rate of mice after I/R injury. MiR-142 directly targeted FoxM1 which was identified by bioinformatics analysis and luciferase activity assay in IEC-6 cells. Inhibition of miR-142 promotes intestinal epithelial proliferation and BF after I/R injury in a FoxM1-mediated manner.

The potential role of miRNAs in the pathogenesis of schizophrenia - A focus on signaling pathways interplay

microRNAs (miRNAs) play a crucial role in brain growth and function. Hence, research on miRNA has the potential to reveal much about the etiology of neuropsychiatric diseases. Among these, schizophrenia (SZ) is a highly intricate and destructive neuropsychiatric ailment that has been thoroughly researched in the field of miRNA. Despite being a relatively recent area of study about miRNAs and SZ, this discipline has advanced enough to justify numerous reviews that summarize the findings from the past to the present. However, most reviews cannot cover all research, thus it is necessary to synthesize the large range of publications on this topic systematically and understandably. Consequently, this review aimed to provide evidence that miRNAs play a role in the pathophysiology and progression of SZ. They have also been investigated for their potential use as biomarkers and therapeutic targets.

The role of microRNAs in neurobiology and pathophysiology of the hippocampus

MicroRNAs (miRNAs) are short non-coding and well-conserved RNAs that are linked to many aspects of development and disorders. MicroRNAs control the expression of genes related to different biological processes and play a prominent role in the harmonious expression of many genes. During neural development of the central nervous system, miRNAs are regulated in time and space. In the mature brain, the dynamic expression of miRNAs continues, highlighting their functional importance in neurons. The hippocampus, as one of the crucial brain structures, is a key component of major functional connections in brain. Gene expression abnormalities in the hippocampus lead to disturbance in neurogenesis, neural maturation and synaptic formation. These disturbances are at the root of several neurological disorders and behavioral deficits, including Alzheimer's disease, epilepsy and schizophrenia. There is strong evidence that abnormalities in miRNAs are contributed in neurodegenerative mechanisms in the hippocampus through imbalanced activity of ion channels, neuronal excitability, synaptic plasticity and neuronal apoptosis. Some miRNAs affect oxidative stress, inflammation, neural differentiation, migration and neurogenesis in the hippocampus. Furthermore, major signaling cascades in neurodegeneration, such as NF-Kβ signaling, PI3/Akt signaling and Notch pathway, are closely modulated by miRNAs. These observations, suggest that microRNAs are significant regulators in the complicated network of gene regulation in the hippocampus. In the current review, we focus on the miRNA functional role in the progression of normal development and neurogenesis of the hippocampus. We also consider how miRNAs in the hippocampus are crucial for gene expression mechanisms in pathophysiological pathways.

MiR-155 promotes inflammation and apoptosis via targeting SIRT1 in hypoxic-ischemic brain damage

Hypoxic-ischemic brain damage (HIBD) is one of the major causes of infant death and long-term neurological disturbances, which puts great pressure on families and society. Previous studies have reported that neuroinflammation regulates the pathogenesis of HIBD. MiR-155 has been reported to participate in many brain injuries; however, its direct implication and related mechanisms are not illuminated in HIBD. Herein, we identified that miR-155 plays a vital role in HIBD both in in vitro and in vivo models. We found that miR-155 promoted inflammation and apoptosis via targeting SIRT1 and negatively regulated its expression levels in oxygen-glucose deprivation/reoxygenation (OGD/R) in an in vitro model. Silencing of SIRT1 reversed the effects of miR-155 inhibitor on apoptosis and the NF-κB pathway in OGD/R-treated PC12 cells and microglia (BV2) cells. Moreover, in a neonatal rat HIBD model, miR-155 enhanced apoptosis and inflammation in the brains of rats with HIBD in vivo. Together, our results demonstrated that miR-155 exerted a negative effect in HIBD by targeting SIRT1, which could contribute to the treatment of neonatal patients with hypoxic-ischemic brain damage.

MicroRNA cerebrospinal fluid profile during the early brain injury period as a biomarker in subarachnoid hemorrhage patients

Introduction

Delayed cerebral ischemia (DCI) is a dreadful complication present in up to 30% of patients with spontaneous subarachnoid hemorrhage (SAH). Indeed, DCI is one of the main causes of long-term disability in SAH, yet its prediction and prevention are troublesome in poor-grade SAH cases. In this prospective study, we explored the potential role of micro ribonucleic acid (microRNA, abbreviated miRNAs)-small non-coding RNAs involved in clue gene regulation at the post-transcriptional level-as biomarkers of neurological outcomes in SAH patients.

Methods

We analyzed the expression of several miRNAs present in the cerebrospinal fluid (CSF) of SAH patients during the early stage of the disease (third-day post-hemorrhage). NanoString Technologies were used for the characterization of the CSF samples.

Results

We found an overexpression of miRNAs in the acute stage of 57 SAH in comparison with 10 non-SAH controls. Moreover, a differential expression of specific miRNAs was detected according to the severity of clinical onset, but also regarding the development of DCI and the midterm functional outcomes.

Conclusion

These observations reinforce the potential utility of miRNAs as prognostic and diagnostic biomarkers in SAH patients. In addition, the identification of specific miRNAs related to SAH evolution might provide insights into their regulatory functions of pathophysiological pathways, such as the TGF-β inflammatory pathway and blood-brain barrier disruption.

A blockade of microRNA-155 signal pathway has a beneficial effect on neural injury after intracerebral haemorrhage via reduction in neuroinflammation and oxidative stress

MicroRNAs (miRNAs) have important contributions to multiple pathophysiological processes for cellular response to stress and are considered as promising therapeutic targets with respect to drug development due to their small size, relative ease of delivery, and sequence specificity. Thus, in the current report, we examined the effects of inhibiting miRNA-155 (miR-155) on the levels of pro-inflammatory cytokines (PICs), oxidative stress products as well as vascular endothelial growth factor (VEGF) in the parietal cortex and hippocampus of rats following intracerebral haemorrhage (ICH). Real time PCR was used to examine the levels of miR-155 in the parietal cortex and hippocampus of rats; and ELISA to measure IL-1β, IL-6 and TNF-α, oxidative 8-iso PGF2α and 8-OHdG, and VEGF. Additionally, modified neurological Severity Score (mNSS) was examined to indicate neurological function in animals. In results, with induction of ICH, the levels of miR-155 were amplified in the parietal cortex and hippocampus and this was accompanied with increases of IL-1β, IL-6 and TNF-α; and 8-iso PGF2α and 8-OHdG. Intracerebroventricular infusion of miR-155 inhibitor attenuated the elevation of PICs and amplification of oxidative stress products. Interestingly, miR-155 inhibitor promoted VEGF levels. Furthermore, inhibition of miR-155 led to improvement of neurological deficits in ICH rats. In conclusion, miR-155 signal in the parietal cortex and hippocampus is engaged in the processes of neural injury during ICH and blocking central miR-155 pathway plays a beneficial role in regulating neurological function via reduction in PICs and products of oxidative stress; and enhancement of VEGF. This has implications to target miR-155 and its downstream signal pathway for neuronal dysfunction and vulnerability related to ICH.

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.

Role of Non-Coding RNA of Human Platelet in Cardiovascular Disease

Cardiovascular diseases (CVD) are the major cause of death in the world. Numerous genetic studies involving transcriptomic approaches aimed at the detailed understanding of the disease and the development of new therapeutic strategies have been conducted over recent years. There has been an increase in research on platelets, which are implicated in CVD due to their capacity to release regulatory molecules that affect various pathways. Platelets secrete over 500 various kinds of molecules to plasma including large amounts of non-coding (nc) RNA (miRNA, lncRNA or circRNA). These ncRNA correspond to 98% of transcripts that are not translated into proteins as they are important regulators in physiology and disease. Thus, miRNAs can direct protein complexes to mRNAs through base-pairing interactions, thus causing translation blockage or/and transcript degradation. The lncRNAs act via different mechanisms by binding to transcription factors. Finally, circRNAs act as regulators of miRNAs, interfering with their action. Alteration in the repertoire and/or the amount of the platelet-secreted ncRNA can trigger CVD as well as other diseases. NcRNAs can serve as effective biomarkers for the disease or as therapeutic targets due to their disease involvement. In this review, we will focus on the most important ncRNAs that are secreted by platelets (9 miRNA, 9 lncRNA and 5 circRNA), their association with CVD, and the contribution of these ncRNA to CVD risk to better understand the relation between ncRNA of human platelet and CVD.

Alzheimer's Disease and microRNA-132: A Widespread Pathological Factor and Potential Therapeutic Target

Alzheimer's disease (AD) is a common neurodegenerative disease in the elderly and is the most common type of dementia. AD is mostly gradual onset, and involves slow, progressive mental decline, accompanied by personality changes; the incidence of AD gradually increases with age. The etiology of AD is unknown, although it is currently believed to be related to abnormal deposition of amyloid β-protein (Aβ) in the brain, hyperphosphorylation of microtubule-associated protein tau, and the release of various cytokines, complements, activators and chemokines by cells. MicroRNAs (miRNAs) are a class of highly conserved non-coding RNAs that regulate gene expression at the post-transcriptional level, and manipulate the functions of intracellular proteins and physiological processes. Emerging studies have shown that miRNA plays an important role in regulating AD-related genes. MiR-132 is known as "NeurimmiR" due to its involvement in numerous neurophysiological and pathological processes. Accumulating pre-clinical results suggest that miR-132 may be involved in the progression of Aβ and tau pathology. Moreover, clinical studies have indicated that decreased circulating miR-132 levels could be used a potential diagnostic biomarker in AD. Here, we review the pathogenic role of miR-132 activity in AD, and the potential of targeting miR-132 for developing future therapeutic strategies.

Nanoparticle Delivered Anti-miR-141-3p for Stroke Therapy

Ischemic stroke and factors modifying ischemic stroke responses, such as social isolation, contribute to long-term disability worldwide. Several studies demonstrated that the aberrant levels of microRNAs contribute to ischemic stroke injury. In prior studies, we established that miR-141-3p increases after ischemic stroke and post-stroke isolation. Herein, we explored two different anti-miR oligonucleotides; peptide nucleic acid (PNAs) and phosphorothioates (PS) for ischemic stroke therapy. We used US FDA approved biocompatible poly (lactic-co-glycolic acid) (PLGA)-based nanoparticle formulations for delivery. The PNA and PS anti-miRs were encapsulated in PLGA nanoparticles by double emulsion solvent evaporation technique. All the formulated nanoparticles showed uniform morphology, size, distribution, and surface charge density. Nanoparticles also exhibited a controlled nucleic acid release profile for 48 h. Further, we performed in vivo studies in the mouse model of ischemic stroke. Ischemic stroke was induced by transient (60 min) occlusion of middle cerebral artery occlusion followed by a reperfusion for 48 or 72 h. We assessed the blood-brain barrier permeability of PLGA NPs containing fluorophore (TAMRA) anti-miR probe after systemic delivery. Confocal imaging shows uptake of fluorophore tagged anti-miR in the brain parenchyma. Next, we evaluated the therapeutic efficacy after systemic delivery of nanoparticles containing PNA and PS anti-miR-141-3p in mice after stroke. Post-treatment differentially reduced both miR-141-3p levels in brain tissue and infarct injury. We noted PNA-based anti-miR showed superior efficacy compared to PS-based anti-miR. Herein, we successfully established that nanoparticles encapsulating PNA or PS-based anti-miRs-141-3p probes could be used as a potential treatment for ischemic stroke.

Circulating miR-155 and JAK2/STAT3 Axis in Acute Ischemic Stroke Patients and Its Relation to Post-Ischemic Inflammation and Associated Ischemic Stroke Risk Factors

Background

“Micro RNAs and their target genes recently have been identified to play a crucial role in the molecular pathogenesis of post-stroke ischemic cellular injury, which elucidates their new role in ischemic stroke diagnosis and therapy”. Thus, we evaluated the relative serum expression of miR-155, an inflammatory micro RNA, and the mRNAs (JAK2/STAT3) in acute ischemic stroke patients and its associations with the inflammatory cytokine TNF-α and different stroke risk factors.

Subjects and Methods

The relative expression of serum miR-155 and mRNAs (JAK2/STAT3) was assessed using RT-PCR, serum TNF-α was measured using ELIZA in 46 acute ischemic stroke patients and 50 control subjects. Receiver operating characteristic (ROC) curve was constructed to assess the specificity and sensitivity of circulating miR-155, JAK2/STAT3 as biomarkers for acute ischemic stroke.

Results

Circulating miR-155, JAK2/STAT3 were significantly up-regulated among stroke patients (8.5, 2.9, 4.2 fold respectively, P<0.001) with significant increase in TNF-α (263.8 ± 10.7 pg/mL, P <0.001). MiR-155, JAK2/STAT3 were positively correlated with TNF-α. MiR-155, JAK2/STAT3 were significantly increased in stroke patients and associated with risk factors such as hypertension, carotid atherosclerosis, and atrial fibrillation. Our study revealed that miR-155 has diagnostic accuracy for acute ischemic stroke where AUC=0.9, (P<0.001).

Conclusion

The elevated expressions of circulating miR-155, JAK2/STAT3, and TNF-α in acute ischemic stroke patients could trigger post-stroke cellular inflammation. MiR-155 could be used as potential inflammatory biomarker for acute ischemic stroke. However, further clinical studies are still needed to determine the exact role of miRNAs and different signal transduction expressions in the stage of acute ischemic stroke.

Mir-155 knockout protects against ischemia/reperfusion-induced brain injury and hemorrhagic transformation

MiR-155 negatively regulates translation of mRNA targets to proteins involved in processes that modulate ischemic brain injury including neuroinflammation, blood-brain barrier (BBB) permeability, and apoptosis. However, reports of the effect of cerebral miR-155 expression changes after ischemic brain injury are equivocal and miR-155 modulates molecular pathways with opposing effects on these processes. The role of miR-155 in postischemic cerebral hemorrhagic transformation remains unknown. To understand the net effect of complete inactivation of miR-155, miR-155 knockout mice were studied in a cerebral ischemia/reperfusion (I/R) model of infarction and hemorrhagic transformation as compared with those of wild type mice. Wild type and miR-155 knockout mice underwent one hour of middle cerebral artery occlusion (MCAO) followed by up to 71 hours of reperfusion. The effects of miR-155 knockout on cerebral infarct size, incidence and extent of hemorrhagic transformation, and neurological outcome were determined. We found that miR-155 was significantly upregulated after cerebral I/R in wild type mice, and miR-155 knockout mice had comparably smaller cerebral infarct size and improved neurological deficits. Similarly, wild type mice had significant hemorrhagic burden after cerebral I/R, the incidence and volume of which was reduced in miR-155 knockout mice. Although miR-155 can have opposite effects on cerebral I/R-injury-related processes, the net effect of miR-155 knockout is neuroprotective. Thus, the increase in miR-155 expression observed after cerebral I/R may be considered deleterious and inhibition of this expression and its effects a potential therapeutic target.

Improvement of lung ischemia-reperfusion injury by inhibition of microRNA-155 via reductions in neuroinflammation and oxidative stress of vagal afferent nerve

Lung ischemia–reperfusion injury (LIRI) is a common clinical concern. As the injury occurs, the pulmonary afferent nerves play a key role in regulating respiratory functions under pathophysiological conditions. The present study was to examine the effects of inhibiting microRNA-155 on the levels of proinflammatory cytokines and products of oxidative stress in the pulmonary vagal afferent nerves and the commissural nucleus of the solitary tract (cNTS) after LIRI. A rat model of LIRI was used. ELISA method was employed to examine proinflammatory cytokines, namely, IL-1β, IL-6 and TNF-α; and key biomarkers of oxidative stress, 8-isoprostaglandin F2α (8-iso PGF2α) and 8-hydroxy-2′-deoxyguanosine (8-OHdG). In results, in the process of LIRI, the levels of microRNA-155 were amplified in the vagal afferent nerves and cNTS, and this was accompanied with increases of IL-1β, IL-6 and TNF-α; and 8-iso PGF2α and 8-OHdG. Application of microRNA-155 inhibitor, but not its scramble, attenuated the elevation of proinflammatory cytokines and amplification of 8-iso PGF2α and 8-OHdG in those nerve tissues. In conclusion, we observed the abnormalities in the pulmonary afferent pathways at the levels of the peripheral nerves and brainstem, which is likely to affect respiratory functions as LIRI occurs. Our data suggest that blocking microRNA-155 signal pathways plays a beneficial role in regulating LIRI via inhibiting responses of neuroinflammation and oxidative stress signal pathways to LIRI.

Inhibition of microRNA-155 Alleviates Neurological Dysfunction Following Transient Global Ischemia and Contribution of Neuroinflammation and Oxidative Stress in the Hippocampus

BACKGROUND/AIMS

Central pro-inflammatory cytokine (PIC) signal is involved in neurological deficits after transient global ischemia induced by cardiac arrest (CA). The present study was to examine the role of microRNA- 155 (miR-155) in regulating IL-1β, IL-6 and TNF-α in the hippocampus of rats with induction of CA. We further examined the levels of products of oxidative stress 8-isoprostaglandin F2α (8-iso PGF2α, indication of oxidative stress); and 8-hydroxy-2'-deoxyguanosine (8-OHdG, indication of protein oxidation) after cerebral inhibition of miR-155.

METHODS

CA was induced by asphyxia and followed by cardiopulmonary resuscitation in rats. ELISA and western blot analysis were used to determine the levels of PICs and products of oxidative stress; and the protein expression of NADPH oxidase (NOXs) in the hippocampus. In addition, neurological severity score and brain edema were examined to assess neurological functions.

RESULTS

We observed amplification of IL-1β, IL-6 and TNF-α along with 8-iso PGF2α and 8-OHdG in the hippocampus of CA rats. Cerebral administration of miR-155 inhibitor diminished upregulation of PICs in the hippocampus. This also attenuated products of oxidative stress and upregulation of NOX4. Notably, inhibition of miR-155 improved neurological severity score and brain edema and this was linked to signal pathways of PIC and oxidative stress.

CONCLUSION

We showed the significant role of blocking miR-155 signal in improving the neurological function in CA rats likely via inhibition of signal pathways of neuroinflammation and oxidative stress, suggesting that miR-155 may be a target in preventing and/or alleviating development of the impaired neurological functions during CA-evoked global cerebral ischemia.

Systemic exosomal miR-193b-3p delivery attenuates neuroinflammation in early brain injury after subarachnoid hemorrhage in mice

Background

Inflammation is a potential crucial factor in the pathogenesis of subarachnoid hemorrhage (SAH). Circulating microRNAs (miRNAs) are involved in the regulation of diverse aspects of neuronal dysfunction. The therapeutic potential of miRNAs has been demonstrated in several CNS disorders and is thought to involve modulation of neuroinflammation. Here, we found that peripherally injected modified exosomes (Exos) delivered miRNAs to the brains of mice with SAH and that the potential mechanism was regulated by regulation of neuroinflammation.

Methods

Next-generation sequencing (NGS) and qRT-PCR were used to define the global miRNA profile of plasma exosomes in aSAH patients and healthy controls. We peripherally injected RVG/Exos/miR-193b-3p to achieve delivery of miR-193b-3p to the brain of mice with SAH. The effects of miR-193b-3p on SAH were assayed using a neurological score, brain water content, blood-brain barrier (BBB) injury, and Fluoro-Jade C (FJC) staining. Western blotting analysis, enzyme-linked immunosorbent assay (ELISA), and qRT-PCR were used to measure various proteins and mRNA levels.

Results

NGS and qRT-PCR revealed that four circulating exosomal miRNAs were differentially expressed. RVG/Exos exhibited improved targeting to the brains of SAH mice. MiR-193b-3p suppressed the expression and activity of HDAC3, upregulating the acetylation of NF-κB p65. Finally, miR-193b-3p treatment mitigated the neurological behavioral impairment, brain edema, BBB injury, and neurodegeneration induced by SAH, and reduced inflammatory cytokine expression in the brains of mice after SAH.

Conclusions

Exos/miR-193b-3p treatment attenuated the inflammatory response by acetylation of the NF-κB p65 via suppressed expression and activity of HDAC3. These effects alleviated neurobehavioral impairments and neuroinflammation following SAH.

Association of miR-155 and Angiotensin Receptor Type 1 Polymorphisms with the Risk of Ischemic Stroke in a Chinese Population

There is increasing evidence suggesting that dysregulation of miR-155 and its target angiotensin receptor type 1 (AT1R) are linked to the incidence of ischemic stroke (IS), but the underlying mechanisms remain to be clarified. In this study, we therefore sought to investigate how miR-155 and AT1R polymorphisms affect IS risk. We included 579 IS patients and 509 age-matched controls in the present analysis, genotyping individuals for the rs767649 polymorphism in miR-155, as well as for the rs1492099 and rs275653 polymorphisms in AT1R via iMLDR-TM genotyping technology. The allele and genotype frequencies for the assessed polymorphisms were comparable in IS patients and controls, without any detectable association between AT1R haplotype and IS risk. We conducted additional trial of ORG 10172 in acute stroke treatment-mediated stratification, which indicated that the AT1R rs1492099 T allele was linked to a decreased risk of large-artery atherosclerosis (LAA) stroke. We further found that those with the AT1R rs275653 AA genotype had a decreased risk of small-artery occlusion (SAO) strokes. We further confirmed elevated miR-155 expression in IS patients, but observed no link between the rs767649 polymorphism and expression of this microRNA. Similarly, rs1492099 and rs275653 polymorphisms did not impact AT1R expression levels. The miR-155 rs767649 polymorphism does not seem to be a key determinant of IS risk, whereas the AT1R rs1492099 polymorphism is linked to reduced LAA-stroke risk, and the rs275653 AA genotype is potentially protective against SAO strokes.

The Involvement and Therapy Target of Immune Cells After Ischemic Stroke

After ischemic stroke, the integrity of the blood-brain barrier is compromised. Peripheral immune cells, including neutrophils, T cells, B cells, dendritic cells, and macrophages, infiltrate into the ischemic brain tissue and play an important role in regulating the progression of ischemic brain injury. In this review, we will discuss the role of different immune cells after stroke in the secondary inflammatory reaction and focus on the phenotypes and functions of macrophages in ischemic stroke, as well as briefly introduce the anti-ischemic stroke therapy targeting macrophages.

Role of microRNA-155 in modifying neuroinflammation and γ-aminobutyric acid transporters in specific central regions after post-ischaemic seizures

In the central nervous system, interleukin (IL)‐1β, IL‐6 and tumour necrosis factor (TNF)‐α have a regulatory role in pathophysiological processes of epilepsy. In addition, γ‐aminobutyric acid (GABA) transporter type 1 and type 3 (GAT‐1 and GAT‐3) modulate the levels of extracellular GABA in involvement in the neuroinflammation on epileptogenesis. Thus, in the current report we examined the effects of inhibiting microRNA‐155 (miR‐155) on the levels of IL‐1β, IL‐6 and TNF‐α, and expression of GAT‐1 and GAT‐3 in the parietal cortex, hippocampus and amygdala of rats with nonconvulsive seizure (NCS) following cerebral ischaemia. Real time RT‐PCR, ELISA and Western blot analysis were used to examine the miR‐155, proinflammatory cytokines (PICs) and GAT‐1/GAT‐3 respectively. With induction of NCS, the levels of miR‐155 were amplified in the parietal cortex, hippocampus and amygdala and this was accompanied with increases of IL‐1β, IL‐6 and TNF‐α. In those central areas, expression of GAT‐1 and GAT‐3 was upregulated; and GABA was reduced in rats following NCS. Intracerebroventricular infusion of miR‐155 inhibitor attenuated the elevation of PICs, amplification of GAT‐1 and GAT‐3 and impairment of GABA. Furthermore, inhibition of miR‐155 decreased the number of NCS events following cerebral ischaemia. Inhibition of miR‐155 further improved post‐ischaemia‐evoked NCS by altering neuroinflammation‐GABA signal pathways in the parietal cortex, hippocampus and amygdala. Results suggest the role of miR‐155 in regulating post‐ischaemic seizures via PICs‐GABA mechanisms.

Emerging Roles of miRNAs in Brain Development and Perinatal Brain Injury

In human beings the immature brain is highly plastic and depending on the stage of gestation is particularly vulnerable to a range of insults that if sufficiently severe, can result in long-term motor, cognitive and behavioral impairment. With improved neonatal care, the incidence of major motor deficits such as cerebral palsy has declined with prematurity. Unfortunately, however, milder forms of injury characterized by diffuse non-cystic white matter lesions within the periventricular region and surrounding white matter, involving loss of oligodendrocyte progenitors and subsequent axonal hypomyelination as the brain matures have not. Existing therapeutic options for treatment of preterm infants have proved inadequate, partly owing to an incomplete understanding of underlying post-injury cellular and molecular changes that lead to poor neurodevelopmental outcomes. This has reinforced the need to improve our understanding of brain plasticity, explore novel solutions for the development of protective strategies, and identify biomarkers. Compelling evidence exists supporting the involvement of microRNAs (miRNAs), a class of small non-coding RNAs, as important post-transcriptional regulators of gene expression with functions including cell fate specification and plasticity of synaptic connections. Importantly, miRNAs are differentially expressed following brain injury, and can be packaged within exosomes/extracellular vesicles, which play a pivotal role in assuring their intercellular communication and passage across the blood-brain barrier. Indeed, an increasing number of investigations have examined the roles of specific miRNAs following injury and regeneration and it is apparent that this field of research could potentially identify protective therapeutic strategies to ameliorate perinatal brain injury. In this review, we discuss the most recent findings of some important miRNAs in relation to the development of the brain, their dysregulation, functions and regulatory roles following brain injury, and discuss how these can be targeted either as biomarkers of injury or neuroprotective agents.

MicroRNAs in brain development and cerebrovascular pathophysiology

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

The MicroRNA Family Both in Normal Development and in Different Diseases: The miR-17-92 Cluster

An increasing number of research studies over recent years have focused on the function of microRNA (miRNA) molecules which have unique characteristics in terms of structure and function. They represent a class of endogenous noncoding single-strand small molecules. An abundance of miRNA clusters has been found in the genomes of various organisms often located in a polycistron. The miR-17-92 family is among the most famous miRNAs and has been identified as an oncogene. The functions of this cluster, together with the seven individual molecules that it comprises, are most related to cancers, so it would not be surprising that they are considered to have involvement in the development of tumors. The miR-17-92 cluster is therefore expected not only to be a tumor marker, but also to perform an important role in the early diagnosis of those diseases and possibly also be a target for tumor biotherapy. The miR-17-92 cluster affects the development of disease by regulating many related cellular processes and multiple target genes. Interestingly, it also has important roles that cannot be ignored in disease of the nervous system and circulation and modulates the growth and development of bone. Therefore, it provides new opportunities for disease prevention, clinical diagnosis, prognosis, and targeted therapy. Here we review the role of the miR-17-92 cluster that has received little attention in relation to neurological diseases, cardiac diseases, and the development of bone and tumors.

The 2018 Otto Aufranc Award: How Does Genome-wide Variation Affect Osteolysis Risk After THA?

BACKGROUND

Periprosthetic osteolysis resulting in aseptic loosening is a leading cause of THA revision. Individuals vary in their susceptibility to osteolysis and heritable factors may contribute to this variation. However, the overall contribution that such variation makes to osteolysis risk is unknown.

QUESTIONS/PURPOSES

We conducted two genome-wide association studies to (1) identify genetic risk loci associated with susceptibility to osteolysis; and (2) identify genetic risk loci associated with time to prosthesis revision for osteolysis.

METHODS

The Norway cohort comprised 2624 patients after THA recruited from the Norwegian Arthroplasty Registry, of whom 779 had undergone revision surgery for osteolysis. The UK cohort included 890 patients previously recruited from hospitals in the north of England, 317 who either had radiographic evidence of and/or had undergone revision surgery for osteolysis. All participants had received a fully cemented or hybrid THA using a small-diameter metal or ceramic-on-conventional polyethylene bearing. Osteolysis susceptibility case-control analyses and quantitative trait analyses for time to prosthesis revision (a proxy measure of the speed of osteolysis onset) in those patients with osteolysis were undertaken in each cohort separately after genome-wide genotyping. Finally, a meta-analysis of the two independent cohort association analysis results was undertaken.

RESULTS

Genome-wide association analysis identified four independent suggestive genetic signals for osteolysis case-control status in the Norwegian cohort and 11 in the UK cohort (p ≤ 5 x 10). After meta-analysis, five independent genetic signals showed a suggestive association with osteolysis case-control status at p ≤ 5 x 10 with the strongest comprising 18 correlated variants on chromosome 7 (lead signal rs850092, p = 1.13 x 10). Genome-wide quantitative trait analysis in cases only showed a total of five and nine independent genetic signals for time to revision at p ≤ 5 x 10, respectively. After meta-analysis, 11 independent genetic signals showed suggestive evidence of an association with time to revision at p ≤ 5 x 10 with the largest association block comprising 174 correlated variants in chromosome 15 (lead signal rs10507055, p = 1.40 x 10).

CONCLUSIONS

We explored the heritable biology of osteolysis at the whole genome level and identify several genetic loci that associate with susceptibility to osteolysis or with premature revision surgery. However, further studies are required to determine a causal association between the identified signals and osteolysis and their functional role in the disease.

CLINICAL RELEVANCE

The identification of novel genetic risk loci for osteolysis enables new investigative avenues for clinical biomarker discovery and therapeutic intervention in this disease.

Sappanone A prevents hypoxia-induced injury in PC-12 cells by down-regulation of miR-15a

OBJECTIVE

We aimed to explore the effect of Sappanone A on neurologic damage induced by hypoxia.

METHODS

PC-12 cells were pre-treated with Sappanone A and were simulated by hypoxia. miRNA transfection was performed to overexpress or suppress the expression of miR-15a in PC-12 cells. Cell viability, apoptosis, migration, and expression levels of miR-15a were tested to evaluate the in vitro impact of Sappanone A on hypoxia-injured PC-12 cells.

RESULTS

Hypoxia exposure induced a significant damage in PC-12 cells, as evidenced by the repressed cell growth, the induced apoptosis and the impaired migrating capacity. Sappanone A pretreatment protected PC-12 cells against hypoxia-mediated cell damage. More interestingly, Sappanone A treatment down-regulated miR-15a, and the neuroprotective effects of Sappanone A were attenuated by miR-15a overexpression while were accelerated by miR-15a suppression. Finally, Sappanone A significantly activated Wnt/β-catenin and PI3K/AKT signaling pathways. And the activation of these two signaling induced by Sappanone A were repressed by miR-15a overexpression and were enhanced by miR-15a suppression.

CONCLUSION

Sappanone A exerted protective activity in PC-12 cells which were stimulated by hypoxia. One of the possible mechanisms of the neuroprotective effect is that: Sappanone A down-regulated the expression of miR-15a, and thus activated Wnt/β-catenin and PI3K/AKT signaling pathways.

Targeting vascular inflammation in ischemic stroke: Recent developments on novel immunomodulatory approaches

Ischemic stroke is a devastating and debilitating medical condition with limited therapeutic options. However, accumulating evidence indicates a central role of inflammation in all aspects of stroke including its initiation, the progression of injury, and recovery or wound healing. A central target of inflammation is disruption of the blood brain barrier or neurovascular unit. Here we discuss recent developments in identifying potential molecular targets and immunomodulatory approaches to preserve or protect barrier function and limit infarct damage and functional impairment. These include blocking harmful inflammatory signaling in endothelial cells, microglia/macrophages, or Th17/γδ T cells with biologics, third generation epoxyeicosatrienoic acid (EET) analogs with extended half-life, and miRNA antagomirs. Complementary beneficial pathways may be enhanced by miRNA mimetics or hyperbaric oxygenation. These immunomodulatory approaches could be used to greatly expand the therapeutic window for thrombolytic treatment with tissue plasminogen activator (t-PA). Moreover, nanoparticle technology allows for the selective targeting of endothelial cells for delivery of DNA/RNA oligonucleotides and neuroprotective drugs. In addition, although likely detrimental to the progression of ischemic stroke by inducing inflammation, oxidative stress, and neuronal cell death, 20-HETE may also reduce susceptibility of onset of ischemic stroke by maintaining autoregulation of cerebral blood flow. Although the interaction between inflammation and stroke is multifaceted, a better understanding of the mechanisms behind the pro-inflammatory state at all stages will hopefully help in developing novel immunomodulatory approaches to improve mortality and functional outcome of those inflicted with ischemic stroke.