microRNA-132 is overexpressed in glia in temporal lobe epilepsy and reduces the expression of pro-epileptogenic factors in human cultured astrocytes

Role of MicroRNAs as post transcription regulators of matrix metalloproteinases and their association in tuberculous meningitis

Matrix metalloproteinases (MMPs) have a role in driving neuroinflammation in infectious as well as non-infectious diseases; however, recent reports have potentiated the role of microRNAs in regulating MMPs at post-transcriptional levels, leading to dysregulation of crucial MMP functions like tissue remodelling, blood brain barrier integrity, etc. In present study, microRNAs regulating MMPs (MMP2 and MMP3) were selected from database search followed by literature support. Expression of these microRNAs i.e., hsa-miR-495-3p, hsa-miR-132-3p and hsa-miR-21-5p was assessed by RT-PCR and the protein levels of MMPs were assessed by ELISA in the cerebrospinal fluid (CSF) of tuberculous meningitis (TBM) patients, healthy controls (HC) and non-infectious neuroinflammatory disease (NID) patients. The expression of hsa-miR-495-3p and hsa-miR-132-3p showed downregulation in TBM while hsa-miR-21-5p was overexpressed as compared to healthy controls. Moreover, MMP levels were found to be deranged with a significant increase in MMP3 levels in the TBM and NID patients compared to HC group. These observations highlight dysregulated microRNAs (hsa-miR-495-3p, hsa-miR-21-5p and hsa-miR-132-3p) levels might impair the levels of MMPs (MMP2 and MMP3) leading to neuroinflammation in TBM and NID population. These findings can further be applied to target these microRNAs for developing newer treatment modalities for better complication management.

Epigenetics and the neurodegenerative process

Neurological diseases are multifactorial, genetic and environmental. Environmental factors such as diet, physical activity and emotional state are epigenetic factors. Environmental markers are responsible for epigenetic modifications. The effect of epigenetic changes is increased inflammation of the nervous system and neuronal damage. In recent years, it has been shown that epigenetic changes may cause an increased risk of neurological disorders but, currently, the relationship between epigenetic modifications and neurodegeneration remains unclear. This review summarizes current knowledge about neurological disorders caused by epigenetic changes in diseases such as Alzheimer's disease, Parkinson's disease, stroke and epilepsy. Advances in epigenetic techniques may be key to understanding the epigenetics of central changes in neurological diseases.

The emerging role of miRNAs in epilepsy: From molecular signatures to diagnostic potential

Epilepsy is a medical condition characterized by intermittent seizures accompanied by changes in consciousness. Epilepsy significantly impairs the daily functioning and overall well-being of affected individuals. Epilepsy is a chronic neurological disorder characterized by recurrent seizures resulting from various dysfunctions in brain activity. The molecular processes underlying changes in neuronal structure, impaired apoptotic responses in neurons, and disruption of regenerative pathways in glial cells in epilepsy remain unknown. MicroRNAs (miRNAs) play a crucial role in regulating apoptosis, autophagy, oxidative stress, neuroinflammation, and the body's regenerative and immune responses. miRNAs have been shown to influence many pathogenic processes in epilepsy including inflammatory responses, neuronal necrosis and apoptosis, dendritic growth, synaptic remodeling, and other processes related to the development of epilepsy. Therefore, the purpose of our current analysis was to determine the role of miRNAs in the etiology and progression of epilepsy. Furthermore, they have been examined for their potential application as biomarkers and therapeutic targets.

Epigenetic regulation in epilepsy: A novel mechanism and therapeutic strategy for epilepsy

Epilepsy is a common neurological disorder characterized by recurrent seizures with excessive and abnormal neuronal discharges. Epileptogenesis is usually involved in neuropathological processes such as ion channel dysfunction, neuronal injury, inflammatory response, synaptic plasticity, gliocyte proliferation and mossy fiber sprouting, currently the pathogenesis of epilepsy is not yet completely understood. A growing body of studies have shown that epigenetic regulation, such as histone modifications, DNA methylation, noncoding RNAs (ncRNAs), N6-methyladenosine (m6A) and restrictive element-1 silencing transcription factor/neuron-restrictive silencing factor (REST/NRSF) are also involved in epilepsy. Through epigenetic studies, we found that the synaptic dysfunction, nerve damage, cognitive dysfunction and brain development abnormalities are affected by epigenetic regulation of epilepsy-related genes in patients with epilepsy. However, the functional roles of epigenetics in pathogenesis and treatment of epilepsy are still to be explored. Therefore, profiling the array of genes that are epigenetically dysregulated in epileptogenesis is likely to advance our understanding of the mechanisms underlying the pathophysiology of epilepsy and may for the amelioration of these serious human conditions provide novel insight into therapeutic strategies and diagnostic biomarkers for epilepsy to improve serious human condition.

Mechanisms of microRNA-132 in central neurodegenerative diseases: A comprehensive review

MicroRNA-132 (miR-132) is a highly conserved molecule that plays a crucial regulatory role in central nervous system (CNS) disorders. The expression levels of miR-132 exhibit variability in various neurological disorders and have been closely linked to disease onset and progression. The expression level of miR-132 in the CNS is regulated by a diverse range of stimuli and signaling pathways, including neuronal migration and integration, dendritic outgrowth, and complexity, synaptogenesis, synaptic plasticity, as well as inflammation and apoptosis activation. The aberrant expression of miR-132 in various central neurodegenerative diseases has garnered widespread attention. Clinical studies have revealed altered miR-132 expression levels in both chronic and acute CNS diseases, positioning miR-132 as a potential biomarker or therapeutic target. An in-depth exploration of miR-132 holds the promise of enhancing our understanding of the mechanisms underlying CNS diseases, thereby offering novel insights and strategies for disease diagnosis and treatment. It is anticipated that this review will assist researchers in recognizing the potential value of miR-132 and in generating innovative ideas for clinical trials related to CNS degenerative diseases.

miRNAs: Targets to Investigate Herpesvirus Infection Associated with Neurological Disorders

Herpesvirus is associated with various neurological disorders and a specific diagnosis is associated with a better prognosis. MicroRNAs (miRNAs) are potential diagnostic and prognostic biomarkers of neurological diseases triggered by herpetic infection. In this review, we discuss miRNAs that have been associated with neurological disorders related to the action of herpesviruses. Human miRNAs and herpesvirus-encoded miRNAs were listed and discussed. This review article will be valuable in stimulating the search for new diagnostic and prognosis alternatives and understanding the role of these miRNAs in neurological diseases triggered by herpesviruses.

Progress in TLE treatment from 2003 to 2023: scientific measurement and visual analysis based on CiteSpace

Objective

Temporal lobe epilepsy (TLE) is the most common cause of drug-resistant epilepsy and can be treated surgically to control seizures. In this study, we analyzed the relevant research literature in the field of temporal lobe epilepsy (TLE) treatment to understand the background, hotspots, and trends in TLE treatment research.

Methods

We discussed the trend, frontier, and hotspot of scientific output in TLE treatment research in the world in the last 20 years by searching the core collection of the Web of Science database. Excel and CiteSpace software were used to analyze the basic data of the literature.

Result

We identified a total of 2,051 publications on TLE treatment from 75 countries between 2003 and 2023. We found that the publication rate was generally increasing. The United States was the most publishing country; among the research institutions on TLE treatment, the University of California system published the most relevant literature and collaborated the most with other institutions. The co-citation of literature, keyword co-occurrence, and its clustering analysis showed that the early studies focused on open surgical treatment, mainly by lobectomy. In recent years, the attention given to stereotactic, microsurgery, and other surgical techniques has gradually increased, and the burst analysis indicated that new research hotspots may appear in the future in the areas of improved surgical procedures and mechanism research.

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.

microRNA-132 regulates gene expression programs involved in microglial homeostasis

microRNA-132 (miR-132), a known neuronal regulator, is one of the most robustly downregulated microRNAs (miRNAs) in the brain of Alzheimer's disease (AD) patients. Increasing miR-132 in AD mouse brain ameliorates amyloid and Tau pathologies, and also restores adult hippocampal neurogenesis and memory deficits. However, the functional pleiotropy of miRNAs requires in-depth analysis of the effects of miR-132 supplementation before it can be moved forward for AD therapy. We employ here miR-132 loss- and gain-of-function approaches using single-cell transcriptomics, proteomics, and in silico AGO-CLIP datasets to identify molecular pathways targeted by miR-132 in mouse hippocampus. We find that miR-132 modulation significantly affects the transition of microglia from a disease-associated to a homeostatic cell state. We confirm the regulatory role of miR-132 in shifting microglial cell states using human microglial cultures derived from induced pluripotent stem cells.

Biogenesis, Composition and Potential Therapeutic Applications of Mesenchymal Stem Cells Derived Exosomes in Various Diseases

Exosomes are nanovesicles with a wide range of chemical compositions used in many different applications. Mesenchymal stem cell-derived exosomes (MSCs-EXOs) are spherical vesicles that have been shown to mediate tissue regeneration in a variety of diseases, including neurological, autoimmune and inflammatory, cancer, ischemic heart disease, lung injury, and liver fibrosis. They can modulate the immune response by interacting with immune effector cells due to the presence of anti-inflammatory compounds and are involved in intercellular communication through various types of cargo. MSCs-EXOs exhibit cytokine storm-mitigating properties in response to COVID-19. This review discussed the potential function of MSCs-EXOs in a variety of diseases including neurological, notably epileptic encephalopathy and Parkinson's disease, cancer, angiogenesis, autoimmune and inflammatory diseases. We provided an overview of exosome biogenesis and factors that regulate exosome biogenesis. Additionally, we highlight the functions and potential use of MSCs-EXOs in the treatment of the inflammatory disease COVID-19. Finally, we covered a strategies and challenges of MSCs-EXOs. Finally, we discuss conclusion and future perspectives of MSCs-EXOs.

Regulation of Glial Function by Noncoding RNA in Central Nervous System Disease

Non-coding RNAs (ncRNAs) are a class of functional RNAs that play critical roles in different diseases. NcRNAs include microRNAs, long ncRNAs, and circular RNAs. They are highly expressed in the brain and are involved in the regulation of physiological and pathophysiological processes of central nervous system (CNS) diseases. Mounting evidence indicates that ncRNAs play key roles in CNS diseases. Further elucidating the mechanisms of ncRNA underlying the process of regulating glial function that may lead to the identification of novel therapeutic targets for CNS diseases.

Circulating miR-146a-5p and miR-132-3p as potential diagnostic biomarkers in epilepsy

OBJECTIVE

MiRNAs are important gene-regulating agents in epilepsy development, according to new research. The purpose of this study is to investigate the relationship between serum expression of miR-146a-5p and miR-132-3p and epilepsy in Egyptian patients as potential diagnostic and therapeutic biomarkers.

METHODS

MiR-146a-5p and miR-132-3p were measured in the serum of 40 adult epilepsy patients and 40 controls using real-time polymerase chain reaction. The comparative cycle threshold (CT) approach (2^-ΔΔCT) was used to compute relative expression levels, which were normalized to cel-miR-39 expression and compared to healthy controls. The diagnostic performance of miR-146a-5p and miR-132-3p was assessed using receiver operating characteristic curve analysis.

RESULTS

The relative expression levels of miR-146a-5p and miR-132-3p in serum were considerably greater in epilepsy patients than in the control group. There was a significant difference in the miRNA-146a-5p relative expression in the focal group when the non-responders were compared with the responders' groups, and a significant difference when comparing the non-responders' focal and the non-responders' generalized groups, however, univariate logistic regression analysis revealed that increased seizure frequency is the only risk factor among all factors affecting the drug response There was a significant difference in epilepsy duration between miR-132-3p high and low expression. With an area under the curve of 0.714 (95% C. I 0.598-0.830; P = 0.001), the combined miR-146a-5p and miR-132-3p serum levels performed better than each separately as a diagnostic biomarker to distinguish epilepsy patients from controls.

SIGNIFICANCE

The findings imply that both miR-146a-5p and miR-132-3p may be involved in epileptogenesis regardless of epilepsy subtypes. Although the combined circulating miRNAs may be useful as a diagnostic biomarker, they are not a predictor of drug response. MiR-132-3p might be used to predict epilepsy's prognosis by demonstrating its chronicity.

Discovery and Validation of Circulating microRNAs as Biomarkers for Epileptogenesis after Experimental Traumatic Brain Injury-The EPITARGET Cohort

Traumatic brain injury (TBI) causes 10-20% of structural epilepsies and 5% of all epilepsies. The lack of prognostic biomarkers for post-traumatic epilepsy (PTE) is a major obstacle to the development of anti-epileptogenic treatments. Previous studies revealed TBI-induced alterations in blood microRNA (miRNA) levels, and patients with epilepsy exhibit dysregulation of blood miRNAs. We hypothesized that acutely altered plasma miRNAs could serve as prognostic biomarkers for brain damage severity and the development of PTE. To investigate this, epileptogenesis was induced in adult male Sprague Dawley rats by lateral fluid-percussion-induced TBI. Epilepsy was defined as the occurrence of at least one unprovoked seizure during continuous 1-month video-electroencephalography monitoring in the sixth post-TBI month. Cortical pathology was analyzed by magnetic resonance imaging on day 2 (D2), D7, and D21, and by histology 6 months post-TBI. Small RNA sequencing was performed from tail-vein plasma samples on D2 and D9 after TBI (n = 16, 7 with and 9 without epilepsy) or sham operation (n = 4). The most promising miRNA biomarker candidates were validated by droplet digital polymerase chain reaction in a validation cohort of 115 rats (8 naïve, 17 sham, and 90 TBI rats [21 with epilepsy]). These included 7 brain-enriched plasma miRNAs (miR-434-3p, miR-9a-3p, miR-136-3p, miR-323-3p, miR-124-3p, miR-212-3p, and miR-132-3p) that were upregulated on D2 post-TBI (p < 0.001 for all compared with naïve rats). The acute post-TBI plasma miRNA profile did not predict the subsequent development of PTE or PTE severity. Plasma miRNA levels, however, predicted the cortical pathology severity on D2 (Spearman ρ = 0.345-0.582, p < 0.001), D9 (ρ = 0.287-0.522, p < 0.001-0.01), D21 (ρ = 0.269-0.581, p < 0.001-0.05) and at 6 months post-TBI (ρ = 0.230-0.433, p < 0.001-0.05). We found that the levels of 6 of 7 miRNAs also reflected mild brain injury caused by the craniotomy during sham operation (ROC AUC 0.76-0.96, p < 0.001-0.05). In conclusion, our findings revealed that increased levels of neuronally enriched miRNAs in the blood circulation after TBI reflect the extent of cortical injury in the brain but do not predict PTE development.

Radiotherapy of the Hepatocellular Carcinoma in Mice Has a Time-Of-Day-Dependent Impact on the Mouse Hippocampus

Chronic liver diseases including hepatocellular carcinoma (HCC) create a state of chronic inflammation that affects the brain via the liver-brain axis leading to an alteration of neurotransmission and cognition. However, little is known about the effects of HCC on the hippocampus, the key brain region for learning and memory. Moreover, radiotherapy used to treat HCC has severe side effects that impair patients' life quality. Thus, designing optimal strategies, such as chronotherapy, to enhance the efficacy and reduce the side effects of HCC treatment is critically important. We addressed the effects of HCC and the timed administration of radiotherapy in mice on the expression of pro-inflammatory cytokines, clock genes, markers for glial activation, oxidative stress, neuronal activity and proliferation in the hippocampal neurogenic niche. Our data showed that HCC induced the upregulation of genes encoding for pro-inflammatory cytokines, altered clock gene expressions and reduced proliferation in the hippocampus. Radiotherapy, in particular when applied during the light/inactive phase enhanced all these effects in addition to glial activation, increased oxidative stress, decreased neuronal activity and increased levels of phospho(p)-ERK. Our results suggested an interaction of the circadian molecular clockwork and the brain's innate immune system as key players in liver-brain crosstalk in HCC and that radiotherapy when applied during the light/inactive phase induced the most profound alterations in the hippocampus.

Silencing of miR-132-3p protects against neuronal injury following status epilepticus by inhibiting IL-1β-induced reactive astrocyte (A1) polarization

Mesial temporal lobe epilepsy (MTLE) is one of the most common refractory epilepsies and is usually accompanied by a range of brain pathological changes, such as neuronal injury and astrocytosis. Naïve astrocytes are readily converted to cytotoxic reactive astrocytes (A1) in response to inflammatory stimulation, suppressing the polarization of A1 protects against neuronal death in early central nervous system injury. Our previous study found that pro-inflammatory cytokines and miR-132-3p (hereinafter referred to as "miR-132") expression were upregulated, but how miR-132 affected reactive astrocyte polarization and neuronal damage during epilepsy is not fully understood. Here, we aimed to explore the effect and mechanism of miR-132 on A1 polarization. Our results confirmed that A1 markers were significantly elevated in the hippocampus of MTLE rats and IL-1β-treated primary astrocytes. In vivo, knockdown of miR-132 by lateral ventricular injection reduced A1 astrocytes, neuronal loss, mossy fiber sprouting, and remitted the severity of status epilepticus and the recurrence of spontaneous recurrent seizures. In vitro, the neuronal cell viability and axon length were reduced by additional treatment with A1 astrocyte conditioned media (ACM), and downregulation of astrocyte miR-132 rescued the inhibition of cell activity by A1 ACM, while the length of axons was further inhibited. The regulation of miR-132 on A1 astrocytes may be related to its target gene expression. Our results show that interfering with astrocyte polarization may be a breakthrough in the treatment of refractory epilepsy, which may extend to the research of other astrocyte polarization-mediated brain injuries.

FOXO4 alleviates hippocampal neuronal damage in epileptic mice via the miR-138-5p/ROCK2 axis

Epilepsy (EP) is one of the most universal neurological disorders. This study investigated the mechanism of forkhead box protein O4 (FOXO4) on hippocampal neuronal damage in EP mice. Initially, the EP mouse model and the in vitro HT-22 cell model were established. EP seizures and neuronal damage in mice were assessed. FOXO4, microRNA (miR)-138-5p, and rho-associated coiled-coil containing protein kinase 2 (ROCK2) levels in hippocampal tissues or HT-22 cells were examined. The cell viability and apoptosis of HT-22 cells were determined. The concentrations of oxidative stress markers and the levels of inflammatory cytokines in hippocampal tissues or HT-22 cells were detected. We found that FOXO4 was poorly expressed in EP. FOXO4 overexpression alleviated hippocampal neuronal damage in EP mice and improved HT-22 cell viability and inhibited apoptosis, and decreased oxidative stress and inflammation in hippocampal tissue and HT-22 cells. The bindings of miR-138-5p to FOXO4 and ROCK2 were analyzed, which showed that FOXO4 promoted miR-138-5p via binding to the miR-138-5p promoter region, and miR-138-5p inhibited ROCK2 expression. Joint experiments showed that miR-138-5p suppression or ROCK2 overexpression reversed the alleviation of FOXO4 overexpression on hippocampal neuronal damage. FOXO4 inhibited ROCK2 expression via promoting miR-138-5p expression, thus alleviating hippocampal neuronal damage in EP mice.

The Coordination of mTOR Signaling and Non-Coding RNA in Regulating Epileptic Neuroinflammation

Epilepsy accounts for a significant proportion of the burden of neurological disorders. Neuroinflammation acting as the inflammatory response to epileptic seizures is characterized by aberrant regulation of inflammatory cells and molecules, and has been regarded as a key process in epilepsy where mTOR signaling serves as a pivotal modulator. Meanwhile, accumulating evidence has revealed that non-coding RNAs (ncRNAs) interfering with mTOR signaling are involved in neuroinflammation and therefore articipate in the development and progression of epilepsy. In this review, we highlight recent advances in the regulation of mTOR on neuroinflammatory cells and mediators, and feature the progresses of the interaction between ncRNAs and mTOR in epileptic neuroinflammation.

Modulation of Microglia M2 Polarization and Alleviation of Hippocampal Neuron Injury By MiR-106b-5p/RGMa in a Mouse Model of Status Epilepticus

MicroRNAs (miRNAs) regulate gene expression at the post-transcriptional level. The miRNA miR-106b-5p has been linked to epilepsy, but its specific role and mechanism of action remain unclear. This was investigated in the present study using a mouse model of pilocarpine-induced status epilepticus and an in vitro system of HT22 hippocampal cells treated with Mg²⁺-free solution and cocultured with BV2 microglia cells. We found that inhibiting miR-106b-5p expression promoted microglia M2 polarization, reduced the inflammatory response, and alleviated neuronal injury. These effects involved modulation of the repulsive guidance molecule A (RGMa)-Rac1-c-Jun N-terminal kinase (JNK)/p38-mitogen-activated protein kinase (MAPK) signaling axis. Our results suggest that therapeutic strategies targeting miR-106b-5p or downstream factors can be effective in preventing epileptogenesis or treating epilepsy.

miR-132-3p Modulates DUSP9-Dependent p38/JNK Signaling Pathways to Enhance Inflammation in the Amnion Leading to Labor

Labor is a process of inflammation and hormonal changes involving both fetal and maternal compartments. MicroRNA-132-3p (miR-132-3p) has been reported to be involved in the development of inflammation-related diseases. However, little is known about its potential role in labor onset. This study aimed to explore the mechanism of miR-132-3p in amnion for labor initiation. In the mouse amnion membranes, the expression of miR-132-3p was found to increase gradually during late gestation. In human amniotic epithelial cell line (WISH), upregulation of miR-132-3p was found to increase proinflammatory cytokines and cyclooxygenase 2 (COX2) as well as prostaglandin E2 (PGE2), which was suppressed by miR-132-3p inhibitor. Dual-specificity phosphatase 9 (DUSP9) was identified as a novel target gene of miR-132-3p, which could be negatively regulated by miR-132-3p. DUSP9 was present in the mouse amnion epithelial cells, with a decrease in its abundance at 18.5 days post coitum (dpc) relative to 15.5 dpc. Silencing DUSP9 was found to facilitate the expression of proinflammatory cytokines and COX2 as well as PGE2 secretion in WISH cells, which could be attenuated by p38 inhibitor SB203580 or JNK inhibitor SP600125. Additionally, intraperitoneal injection of pregnant mice with miR-132-3p agomir not only caused preterm birth, but also promoted the abundance of COX2 as well as phosphorylated JNK and p38 levels, and decreased DUSP9 level in mouse amnion membranes. Collectively, miR-132-3p might participate in inflammation and PGE2 release via targeting DUSP9-dependent p38 and JNK signaling pathways to cause preterm birth.

Aberrant expression of miRNAs in epilepsy

Epilepsy is manifested by intermittent convulsions and alterations in consciousness. This disorder has serious effects on daily functions and physical and mental health of affected patients. A variety of temporary irregularities in the function of brain can results in epilepsy. The molecular mechanism of epilepsy and the underlying causes of abnormal apoptotic responses in neurons, dysregulation of regenerative mechanisms in glial cells and abnormal immune reactions in the context of epilepsy are not clear. microRNAs (miRNAs) as important regulators of cell apoptosis as well as regenerative and immune responses have been shown to affect pathologic events in epilepsy. In the current review, we aimed at defining the role of miRNAs in the pathophysiology of epilepsy. We have listed dysregulated miRNAs in animal models of epilepsy and human subjects. miR-25-3p, miR-494, miR-139-5p, miR-101a-3p, miR-344a, miR-129, miR-298 and miR-187 are among down-regulated miRNAs in epilepsy. Moreover, expressions of miR-132, miR-146a, miR-181a and miR-155 have been reported to be increased in epilepsy. A number of genetic variants within miRNAs can affect risk of epilepsy. We discuss the role of miRNAs in the development of epilepsy.

Adult Neural Stem Cell Regulation by Small Non-coding RNAs: Physiological Significance and Pathological Implications

The adult neurogenic niches are complex multicellular systems, receiving regulatory input from a multitude of intracellular, juxtacrine, and paracrine signals and biological pathways. Within the niches, adult neural stem cells (aNSCs) generate astrocytic and neuronal progeny, with the latter predominating in physiological conditions. The new neurons generated from this neurogenic process are functionally linked to memory, cognition, and mood regulation, while much less is known about the functional contribution of aNSC-derived newborn astrocytes and adult-born oligodendrocytes. Accumulating evidence suggests that the deregulation of aNSCs and their progeny can impact, or can be impacted by, aging and several brain pathologies, including neurodevelopmental and mood disorders, neurodegenerative diseases, and also by insults, such as epileptic seizures, stroke, or traumatic brain injury. Hence, understanding the regulatory underpinnings of aNSC activation, differentiation, and fate commitment could help identify novel therapeutic avenues for a series of pathological conditions. Over the last two decades, small non-coding RNAs (sncRNAs) have emerged as key regulators of NSC fate determination in the adult neurogenic niches. In this review, we synthesize prior knowledge on how sncRNAs, such as microRNAs (miRNAs) and piwi-interacting RNAs (piRNAs), may impact NSC fate determination in the adult brain and we critically assess the functional significance of these events. We discuss the concepts that emerge from these examples and how they could be used to provide a framework for considering aNSC (de)regulation in the pathogenesis and treatment of neurological diseases.

The promise of microRNA-based therapies in Alzheimer's disease: challenges and perspectives

Multi-pathway approaches for the treatment of complex polygenic disorders are emerging as alternatives to classical monotarget therapies and microRNAs are of particular interest in that regard. MicroRNA research has come a long way from their initial discovery to the cumulative appreciation of their regulatory potential in healthy and diseased brain. However, systematic interrogation of putative therapeutic or toxic effects of microRNAs in (models of) Alzheimer's disease is currently missing and fundamental research findings are yet to be translated into clinical applications. Here, we review the literature to summarize the knowledge on microRNA regulation in Alzheimer's pathophysiology and to critically discuss whether and to what extent these increasing insights can be exploited for the development of microRNA-based therapeutics in the clinic.

MicroRNA-221-3p Suppresses the Microglia Activation and Seizures by Inhibiting of HIF-1α in Valproic Acid-Resistant Epilepsy

One-third of patients with epilepsy suffer from drug-resistant epilepsy (DRE). Valproic acid (VPA) is a classic anticonvulsant drug, and its resistance is a crucial predictor of DRE, but the pathogenesis remain unknown. Most patients with VPA-resistant epilepsy appear distinct inflammatory response and local hypoxia. Hypoxia-inducible factor (HIF)-1α is an essential effector molecule of hypoxia and inflammation, and may exert therefore a significant effect on the development of VPA-resistant epilepsy. We systematically assess the significance of HIF-1α on children and mice with VPA-resistant epilepsy, and investigated the micro (mi) RNAs that regulate HIF-1α expression. We established models of VPA-sensitive epilepsy and VPA-resistant epilepsy in mice, and confirmed that they had significant differences in epileptic behavior and electroencephalography data. Through proteomics analysis, we identified that HIF-1α was overexpressed in mice with VPA-resistant epilepsy, and regulated the expression of interleukin-1β and tumor necrosis factor-α. Increased expression of HIF-1α led to the increase of microglia and induced their polarization from the M2 phenotype to M1 phenotype, which triggered the release of proinflammatory mediators. Bioinformatics analysis of public databases demonstrated that miR-221-3p was reduced in VPA-resistant epilepsy, and negatively regulated HIF-1α expression. Intervention using miR-221-3p mimics reduced HIF-1α expression markedly and suppressed the activation of microglia and the release of inflammatory mediators, which relieved epileptic seizures of VPA-resistant epilepsy. These observations reveal miR-221-3p/HIF-1α as essential component in pathogenesis of VPA-resistant epilepsy which represent therapeutic antiseizure targets.

Interleukin-33 and oxidative stress in epilepsy patients

OBJECTIVE

İnflammation and oxidative stress plays an important role in the etiology of epilepsy. Interleukin-33 (IL-33), a new member of the cytokine family associated with interleukin-1 (IL-1), has been found to play a role in pathogenesis of central nervous system diseases and cause the production of proinflammatory cytokines and oxidative stress molecules. Our aim was to investigate IL-33 and oxidative stress values (total antioxidant capacity (TAS), total oxidant capacity (TOS), and oxidative stress index (OSI)) in patients with epilepsy and to evaluate their relationship with each other.

METHODS

The study included 60 patients with epilepsy and 35 healthy controls. The group of patients with epilepsy consisted of 21 patients with treatment-resistant epilepsy and 39 patients with well-controlled epilepsy. The patients with epilepsy were also classified as monotherapy and polytherapy group according to the number of antiepileptic drugs they used, and focal and generalized epilepsy group according to the seizure type. Serum IL-33, TAS, TOS and OSI levels were measured in the patients with epilepsy and the control group.

RESULTS

The mean serum TAS level was significantly lower in the all patients with epilepsy group compared to the control group, and the mean serum IL-33, TOS, and OSI levels were significantly higher. The mean serum TOS and OSI levels were significantly lower and TAS levels were significantly higher in the patients with well-controlled epilepsy than the patients with treatment-resistant epilepsy. While there was a positive correlation between serum IL-33 and OSI levels in the all patients with epilepsy group, a negative correlation was shown between IL-33 and TAS levels.

CONCLUSION

The IL-33/ST2 pathway may represent a new promising therapeutic strategy both for the treatment and the prevention of the disease.

Multi-omic strategies applied to the study of pharmacoresistance in mesial temporal lobe epilepsy

Mesial temporal lobe epilepsy (MTLE) is the most common type of focal epilepsy in adults, and hippocampal sclerosis (HS) is a frequent histopathological feature in patients with MTLE. Pharmacoresistance is present in at least one-third of patients with MTLE with HS (MTLE+HS). Several hypotheses have been proposed to explain the mechanisms of pharmacoresistance in epilepsy, including the effect of genetic and molecular factors. In recent years, the increased knowledge generated by high-throughput omic technologies has significantly improved the power of molecular genetic studies to discover new mechanisms leading to disease and response to treatment. In this review, we present and discuss the contribution of different omic modalities to understand the basic mechanisms determining pharmacoresistance in patients with MTLE+HS. We provide an overview and a critical discussion of the findings, limitations, new approaches, and future directions of these studies to improve the understanding of pharmacoresistance in MTLE+HS. However, it is important to point out that, as with other complex traits, pharmacoresistance to anti-seizure medications is likely a multifactorial condition in which gene-gene and gene-environment interactions play an important role. Thus, studies using multidimensional approaches are more likely to unravel these intricate biological processes.

MicroRNA 223 Targeting ATG16L1 Affects Microglial Autophagy in the Kainic Acid Model of Temporal Lobe Epilepsy

This study aimed to explore whether microRNA (miR) 223 affects microglial autophagy by targeting autophagy-related 16-like 1 (ATG16L1) in the kainic acid (KA) model of temporal lobe epilepsy (TLE). The miRNA and mRNA expression levels were quantified using quantitative real-time polymerase chain reaction (qRT-PCR), and the protein expression was investigated using western blotting. A dual-luciferase reporter assay was used to test the direct interaction between miR 223 and ATG16L1. In situ hybridization was performed to measure the hippocampal expression of miR 223. We used immunofluorescence staining to assess the expression of ATG16L1 and microtubule-associated protein light chain 3 (LC3) in the murine hippocampal microglia. Inhibitor of miR 223 was utilized to investigate the role of miR 223 in TLE, and the epileptic activity was assessed using electroencephalography (EEG). The autophagosomes were observed by transmission electron microscopy. In patients with TLE, the murine KA model of TLE, and the KA-stimulated BV2 cells, miR 223, and sequestosome 1 (SQSTM1/P62) expressions were remarkably increased, whereas ATG16L1 and LC3 levels were significantly decreased. Using a dual-luciferase reporter assay, ATG16L1 was determined as a direct target of miR 223. Treatment with antagomir 223 alleviated epilepsy, prevented abnormalities in EEG recordings and increased the ATG16L1 and LC3 levels in KA-treated mice. Inhibition of miR 223 induced increased autophagy in BV2 cells upon Rapamycin stimulation. These findings show that miR 223 affects microglial autophagy via ATG16L1 in the KA model of TLE. The miR 223/ATG16L1 pathway may offer a new treatment option for TLE.

MicroRNA Dysregulation in Epilepsy: From Pathogenetic Involvement to Diagnostic Biomarker and Therapeutic Agent Development

Epilepsy is the result of a group of transient abnormalities in brain function caused by an abnormal, highly synchronized discharge of brain neurons. MicroRNA (miRNA) is a class of endogenous non-coding single-stranded RNA molecules that participate in a series of important biological processes. Recent studies demonstrated that miRNAs are involved in a variety of central nervous system diseases, including epilepsy. Although the exact mechanism underlying the role of miRNAs in epilepsy pathogenesis is still unclear, these miRNAs may be involved in the inflammatory response in the nervous system, neuronal necrosis and apoptosis, dendritic growth, synaptic remodeling, glial cell proliferation, epileptic circuit formation, impairment of neurotransmitter and receptor function, and other processes. Here, we discuss miRNA metabolism and the roles of miRNA in epilepsy pathogenesis and evaluate miRNA as a potential new biomarker for the diagnosis of epilepsy, which enhances our understanding of disease processes.

AhR Ligands Differentially Regulate miRNA-132 Which Targets HMGB1 and to Control the Differentiation of Tregs and Th-17 Cells During Delayed-Type Hypersensitivity Response

Aryl hydrocarbon receptor (AhR), is a transcription factor and an environmental sensor that has been shown to regulate T cell differentiation. Interestingly, AhR ligands exert varying effects from suppression to exacerbation of inflammation through induction of Tregs and Th-17 cells, respectively. In the current study, we investigated whether the differential effects of AhR ligands on T cell differentiation are mediated by miRNA during delayed-type hypersensitivity (DTH) reaction against methylated Bovine Serum Albumin (mBSA). Treatment of C57BL/6 mice with TCDD attenuated mBSA-mediated DTH response, induced Tregs, decreased Th-17 cells, and caused upregulation of miRNA-132. TCDD caused an increase in several Treg subsets including inducible peripheral, natural thymic, and Th3 cells. Also, TCDD increased TGF-β and Foxp3 expression. In contrast, treating mice with FICZ exacerbated the DTH response, induced inflammatory Th17 cells, induced IL-17, and RORγ. Analysis of miRNA profiles from draining lymph nodes showed that miR-132 was upregulated in the TCDD group and downregulated in the FICZ group. Transfection studies revealed that miRNA-132 targeted High Mobility Group Box 1 (HMGB1). Downregulation of HMGB1 caused an increase in FoxP3+ Treg differentiation and suppression of Th-17 cells while upregulation of HMGB1 caused opposite effects. Moreover, TCDD was less effective in suppressing DTH response and induction of Tregs in mice that were deficient in miR-132. In summary, this study demonstrates that TCDD and FICZ have divergent effects on DTH response and T cell differentiation, which is mediated through, at least in part, regulation of miRNA-132 that targets HMGB1.

The Clinical Significance of miR-135b-5p and Its Role in the Proliferation and Apoptosis of Hippocampus Neurons in Children with Temporal Lobe Epilepsy

Temporal lobe epilepsy (TLE) is the most familiar localized epilepsy in children. MicroRNAs (miRNAs) are essential for the inhibition or promotion of numerous diseases. This study aimed to detect the expression of miR-135b-5p and primarily uncover its underlying function and mechanism in children with TLE. Quantitative real-time polymerase chain reaction was used to evaluate the expression of miR-135b-5p in children with TLE and in a rat model of epilepsy. MTT assay and flow cytometric apoptosis assay were conducted to evaluate the effects of miR-135b-5p on cell viability and apoptosis. Additionally, the dual luciferase reporter assay was performed to confirm the direct target of miR-135b-5p. Our data showed that the expression of miR-135b-5p was significantly decreased in children with TLE and in the epileptic rat neuron model. The dysregulation of miR-135b-5p could serve as a promising diagnostic biomarker for children with TLE. The overexpression of miR-135b-5p moderated the adverse influence on cell viability and apoptosis induced by magnesium-free medium. SIRT1 was identified as a target gene of miR-135b-5p. These results proved that miR-135b-5p might serve as a potential diagnostic biomarker in children with TLE. Overexpression of miR-135b-5p alleviates the postepileptic influence on cell viability and apoptosis by targeting SIRT1.

Prospects and Limitations Related to the Use of MicroRNA as a Biomarker of Epilepsy in Children: A Systematic Review

Epilepsy is one of the most common neurological diseases in children. There is an unmet need for new objective methods that would facilitate and accelerate the diagnostic process, thus improving the prognosis. In many studies, the participation of microRNA in epileptogenesis has been confirmed. Therefore, it seems to be a promising candidate for this role. Scientists show the possibility of using microRNAs as diagnostic and predictive biomarkers as well as novel therapeutic targets. Children with epilepsy would benefit particularly from the use of this innovative method. However, the number of studies related to this age group is very limited. This review is based on 10 studies in children and summarizes the information collected from studies on animal models and the adult population. A total of 136 manuscripts were included in the analysis. The aim of the review was to facilitate the design of studies in children and to draw attention to the challenges and traps related to the analysis of the results. Our review suggests a high potential for the use of microRNAs and the need for further research.

Long Noncoding RNA X-Inactive-Specific Transcript Promotes the Secretion of Inflammatory Cytokines in LPS Stimulated Astrocyte Cell Via Sponging miR-29c-3p and Regulating Nuclear Factor of Activated T cell 5 Expression

BACKGROUND

Astrocyte activation promotes glutamate accumulation and secretion of inflammatory factors, mainly responsible for epilepsy. Long noncoding RNA (lncRNA) X-inactive-specific transcript (XIST) regulates inflammation; however, the biological role and regulatory mechanism of XIST during astrocyte activation remain unclear.

METHODS

In the present study, rat epilepsy model and lipopolysaccharide (LPS)-treated CTX-TNA2 were established. XIST and miR-29c-3p expression were evaluated using quantitative real-time polymerase chain reaction. Nuclear factor of activated T cells 5 (NFAT5) was measured using western blot analysis. Interleukin (IL)-1β, IL-6, tumor necrosis factor-α, and L-glutamate levels in the culture supernatants were assessed using enzyme-linked immunosorbent assay. The binding between XIST and miR-29c-3p and between miR-29c-3p and the 3'-UTR of NFAT5 was analyzed using dual-luciferase reporter, RNA-binding protein immunoprecipitation (RIP), and Biotin pull-down assay. The proliferation and apoptosis were evaluated using CCK8 and flow cytometry, respectively.

RESULTS

XIST expression and NFAT5 protein level was increased, whereas miR-29c-3p expression was decreased in the epilepsy rat model and LPS-treated CTX-TNA2 cells. Silenced XIST expression, miR-29c-3p overexpression, or silenced NFAT5 expression inhibited the secretion of IL-1β, IL-6, and TNF-α and promoted glutamate transport in LPS-treated CTX-TNA2 cells. miR-29c-3p was the potential miRNA sponged by XIST. NFAT5 acted as a direct binding target of miR-29c-3p. Silenced miR-29c-3p expression or NFAT5 overexpression reversed the effect of silenced XIST expression on LPS-treated CTX-TNA2.XIST and miR-29c-3p treatment does not affect NFAT5 mRNA expression, but affects NFAT5 protein level. Furthermore, underexpressed XIST or overexpressed miR-29c-3p in LPS-stimulated CTX-TNA2 can attenuate neuronal apoptosis induced by LPS-stimulated CTX-TNA2.

CONCLUSION

LncRNA XIST promotes the secretion of inflammatory cytokines in LPS- treated CTX-TNA2 via sponging miR-29c-3p and regulating NFAT5 expression.

Circular RNA circ_DROSHA alleviates the neural damage in a cell model of temporal lobe epilepsy through regulating miR-106b-5p/MEF2C axis

Temporal lobe epilepsy (TLE) is the most prevalent form of acquired epilepsy. Circular RNAs (circRNAs) have recently been highlighted as important regulators in TLE. Nevertheless, the role and mechanism of circRNA Drosha ribonuclease III (circ_DROSHA) in TLE pathogenesis are still unknown. Magnesium-free extracellular solution was used to establish the TLE cell model. The levels of circ_DROSHA, myocyte-specific enhancer factor 2C (MEF2C) and miR-106b-5p were determined by qRT-PCR and western blot. Cell proliferation was detected by the Cell Counting-8 Kit (CCK-8) assay, and cell apoptosis was measured by flow cytometry. Targeted relationships among circ_DROSHA, miR-106b-5p and MEF2C were confirmed by a dual-luciferase reporter or RNA immunoprecipitation (RIP) assay. Our data showed that circ_DROSHA was down-regulated in the serum samples of TLE patients and the TLE cell model. Circ_DROSHA up-regulation alleviated the cytotoxicity of the TLE cell model by enhancing cell proliferation and repressing cell apoptosis. Circ_DROSHA directly bound to miR-106b-5p. Moreover, miR-106b-5p represented a downstream effector of circ_DROSHA function. MEF2C was a direct target of miR-106b-5p, and miR-106b-5p knockdown relieved magnesium-free treatment-induced cell injury by up-regulating MEF2C. Furthermore, circ_DROSHA regulated MEF2C expression via sponging miR-106b-5p. Our study suggested that the enforced expression of circ_DROSHA alleviated the cell damage of the TLE cell model at least in part through the regulation of the miR-106b-5p/MEF2C axis.

Epigenetic Regulation of the Hippocampus, with Special Reference to Radiation Exposure

The hippocampus is crucial in learning, memory and emotion processing, and is involved in the development of different neurological and neuropsychological disorders. Several epigenetic factors, including DNA methylation, histone modifications and non-coding RNAs, have been shown to regulate the development and function of the hippocampus, and the alteration of epigenetic regulation may play important roles in the development of neurocognitive and neurodegenerative diseases. This review summarizes the epigenetic modifications of various cell types and processes within the hippocampus and their resulting effects on cognition, memory and overall hippocampal function. In addition, the effects of exposure to radiation that may induce a myriad of epigenetic changes in the hippocampus are reviewed. By assessing and evaluating the current literature, we hope to prompt a more thorough understanding of the molecular mechanisms that underlie radiation-induced epigenetic changes, an area which can be further explored.

Astrocytes as Guardians of Neuronal Excitability: Mechanisms Underlying Epileptogenesis

Astrocytes are key homeostatic regulators in the central nervous system and play important roles in physiology. After brain damage caused by e.g., status epilepticus, traumatic brain injury, or stroke, astrocytes may adopt a reactive phenotype. This process of reactive astrogliosis is important to restore brain homeostasis. However, persistent reactive astrogliosis can be detrimental for the brain and contributes to the development of epilepsy. In this review, we will focus on physiological functions of astrocytes in the normal brain as well as pathophysiological functions in the epileptogenic brain, with a focus on acquired epilepsy. We will discuss the role of astrocyte-related processes in epileptogenesis, including reactive astrogliosis, disturbances in energy supply and metabolism, gliotransmission, and extracellular ion concentrations, as well as blood-brain barrier dysfunction and dysregulation of blood flow. Since dysfunction of astrocytes can contribute to epilepsy, we will also discuss their role as potential targets for new therapeutic strategies.

Increased expression of miR142 and miR155 in glial and immune cells after traumatic brain injury may contribute to neuroinflammation via astrocyte activation

Traumatic brain injury (TBI) is associated with the pathological activation of immune-competent cells in the brain, such as astrocytes, microglia and infiltrating immune blood cells, resulting in chronic inflammation and gliosis. This may contribute to the secondary injury after TBI, thus understanding of these processes is crucial for the development of effective treatments of post-traumatic pathologies. MicroRNAs (miRNAs, miRs) are small noncoding RNAs, functioning as posttranscriptional regulators of gene expression. The increased expression of inflammation-associated microRNAs miR155 and miR142 has been reported after TBI in rats. However, expression of these miRNAs in the human brain post-TBI is not studied and their functions are not well understood. Moreover, circulating miR155 and miR142 are candidate biomarkers. Therefore, we characterized miR142 and miR155 expression in the perilesional cortex and plasma of rats that underwent lateral fluid-percussion injury, a model for TBI and in the human perilesional cortex post-TBI. We demonstrated higher miR155 and miR142 expression in the perilesional cortex of rats 2 weeks post-TBI. In plasma, miR155 was associated with proteins and miR142 with extracellular vesicles, however their expression did not change. In the human perilesional cortex miR155 was most prominently expressed by activated astrocytes, whereas miR142 was expressed predominantly by microglia, macrophages and lymphocytes. Pro-inflammatory medium from macrophage-like cells stimulated miR155 expression in astrocytes and overexpression of miR142 in these cells further potentiated a pro-inflammatory state of activated astrocytes. We conclude that miR155 and miR142 promote brain inflammation via astrocyte activation and may be involved in the secondary brain injury after TBI.

IL-33 Alleviated Brain Damage via Anti-apoptosis, Endoplasmic Reticulum Stress, and Inflammation After Epilepsy

Interleukin (IL)-33 belongs to a novel chromatin-associated cytokine newly recognized by the IL-1 family, and its specific receptor is the orphan IL-1 receptor (ST2). Cumulative evidence suggests that IL-33 plays a crucial effect on the pathological changes and pathogenesis of central nervous system (CNS) diseases and injuries, such as recurrent neonatal seizures (RNS). However, the specific roles of IL-33 and its related molecular mechanisms in RNS remain confused. In the present study, we investigated the protein expression changes and co-localized cell types of IL-33 or ST2, as well as the effect of IL-33 on RNS-induced neurobehavioral defects, weight loss, and apoptosis. Moreover, an inhibitor of IL-33, anti-IL-33 was performed to further exploited underlying mechanisms. We found that administration of IL-33 up-regulated the expression levels of IL-33 and ST2, and increased the number of its co-localization with Olig-2-positive oligodendrocytes and NeuN-positive neurons at 72 h post-RNS. Noteworthily, RNS-induced neurobehavioral deficits, bodyweight loss, and spatial learning and memory impairment, as well as cell apoptosis, were reversed by IL-33 pretreatment. Additionally, the increase in IL-1β and TNF-α levels, up-regulation of ER stress, as well as a decrease in anti-apoptotic protein Bcl-2 and an increase in pro-apoptotic protein CC-3 induced by RNS are prevented by administration of IL-33. Moreover, IL-33 in combination with Anti-IL-33 significantly inverted the effects of IL-33 or Anti-IL-33 alone on apoptosis, ER stress, and inflammation. Collectively, these data suggest that IL-33 attenuates RNS-induced neurobehavioral disorders, bodyweight loss, and spatial learning and memory deficits, at least in part through mechanisms involved in inhibition of apoptosis, ER stress, and neuro-inflammation.

Circulating MicroRNAs from Serum Exosomes May Serve as a Putative Biomarker in the Diagnosis and Treatment of Patients with Focal Cortical Dysplasia

Focal cortical dysplasia (FCD) is a congenital malformation of cortical development where the cortical neurons located in the brain area fail to migrate in the proper formation. Epilepsy, particularly medically refractory epilepsy, is the most common clinical presentation for all types of FCD. This study aimed to explore the expression change of circulating miRNAs in patients with FCD from serum exosomes. A total of nine patients with FCD and four healthy volunteers were enrolled in this study. The serum exosomes were isolated from the peripheral blood of the subjects. Transmission electron microscopy (TEM) was used to identify the exosomes. Both exosomal markers and neuronal markers were detected by Western blotting analysis to prove that we could obtain central nervous system-derived exosomes from the circulation. The expression profiles of circulating exosomal miRNAs were assessed using next-generation sequencing analysis (NGS). We obtained a total of 107 miRNAs with dominant fold change (>2-fold) from both the annotated 5p-arm and 3p-arm of 2780 mature miRNAs. Based on the integrated platform of HMDD v3.2, miRway DB and DIANA-miRPath v3.0 online tools, and confirmed by MiRBase analysis, four potentially predicted miRNAs from serum exosomes in patients with FCD were identified, including miR194-2-5p, miR15a-5p, miR-132-3p, and miR-145-5p. All four miRNAs presented upregulated expression in patients with FCD compared with controls. Through Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis and pathway category of four target miRNAs, we found eight possible signaling pathways that may be related to FCD. Among them, we suggest that the mTOR signaling pathway, PI3K-Akt signaling pathway, p53 signaling pathway, and cell cycle regulation and TGF-beta signaling pathway are high-risk pathways that play a crucial role in the pathogenesis of FCD and refractory epilepsy. Our results suggest that the circulating miRNAs from exosomes may provide a potential biomarker for diagnostic, prognostic, and therapeutic adjuncts in patients with FCD and refractory epilepsy.

Regulatory function of microRNAs in microglia

Microglia are CNS-resident cells involved in immune surveillance and maintenance of intercellular homeostasis, while also contributing to neurologic pathologies. MicroRNAs (miRNAs) are a class of small (~22 nucleotides) single-stranded noncoding RNAs that participate in gene regulation at the post-transcriptional level. miRNAs typically bind to the untranslated region (3' UTR) of RNAs. It has been shown that miRNAs are important players in controlling inflammation and that their abnormal expression is linked to cancer and ageing, and to the onset and progression of neurodegenerative disease. Furthermore, miRNAs participate in intercellular trafficking. Thus, miRNAs are released from cells in a free form, bound to proteins or packaged within extracellular vesicles (EVs), exerting paracrine and long distance signaling. In this review, recent findings on the role of miRNAs as drivers of microglia phenotypic changes and their cotribution in neurological disease are addressed. MAIN POINTS: miRNAs have a key role in microglia function/dysfunction, polarization, and restoration. Microglia are both a source and recipient of extracellular vesicles (EVs) containing miRNAs. Extracellular miRNAs may be found as soluble (free and EV cargo) and protein complexes.

Calcineurin Controls Expression of EAAT1/GLAST in Mouse and Human Cultured Astrocytes through Dynamic Regulation of Protein Synthesis and Degradation

Alterations in the expression of glutamate/aspartate transporter (GLAST) have been associated with several neuropathological conditions including Alzheimer's disease and epilepsy. However, the mechanisms by which GLAST expression is altered are poorly understood. Here we used a combination of pharmacological and genetic approaches coupled with quantitative PCR and Western blot to investigate the mechanism of the regulation of GLAST expression by a Ca²⁺/calmodulin-activated phosphatase calcineurin (CaN). We show that treatment of cultured hippocampal mouse and fetal human astrocytes with a CaN inhibitor FK506 resulted in a dynamic modulation of GLAST protein expression, being downregulated after 24-48 h, but upregulated after 7 days of continuous FK506 (200 nM) treatment. Protein synthesis, as assessed by puromycin incorporation in neo-synthesized polypeptides, was inhibited already after 1 h of FK506 treatment, while the use of a proteasome inhibitor MG132 (1 μM) shows that GLAST protein degradation was only suppressed after 7 days of FK506 treatment. In astrocytes with constitutive genetic ablation of CaN both protein synthesis and degradation were significantly inhibited. Taken together, our data suggest that, in cultured astrocytes, CaN controls GLAST expression at a posttranscriptional level through regulation of GLAST protein synthesis and degradation.

Astrocytic modulation of potassium under seizures

The contribution of an impaired astrocytic K⁺ regulation system to epileptic neuronal hyperexcitability has been increasingly recognized in the last decade. A defective K⁺ regulation leads to an elevated extracellular K⁺ concentration ([K⁺]_o). When [K⁺]_o reaches peaks of 10-12 mM, it is strongly associated with seizure initiation during hypersynchronous neuronal activities. On the other hand, reactive astrocytes during a seizure attack restrict influx of K⁺ across the membrane both passively and actively. In addition to decreased K⁺ buffering, aberrant Ca²⁺ signaling and declined glutamate transport have also been observed in astrogliosis in epileptic specimens, precipitating an increased neuronal discharge and induction of seizures. This review aims to provide an overview of experimental findings that implicated astrocytic modulation of extracellular K⁺ in the mechanism of epileptogenesis.

The Progress in Diagnosis and Treatment of Exosomes and MicroRNAs on Epileptic Comorbidity Depression

The occurrence of epilepsy can increase the incidence of depression, and the risk of epilepsy in the patients with depression is also high, both of which have an adverse effect on the life and the psychology of the patient, which is not conducive to the prognosis of the patients with epilepsy. With lucubrating the function of exosomes and microRNAs, some scholars found that the exosomes and its microRNAs have development prospect in the diagnosis and treatment of the disease. MicroRNAs are involved in the regulation of seizures and depression, as biomarkers, that can significantly improve the management of epileptic patients and play a preventive role in the occurrence of epilepsy and epilepsy depressive disorder. Moreover, due to its regulation to genes, appropriate application of microRNAs may have therapeutic effect on epilepsy and depression with the characteristics of long distance transmission and stability of exosomes, to a certain extent. This provides a great convenience for the diagnosis and treatment of epileptic comorbidity depression.

microRNA-132 is overexpressed in glia in temporal lobe epilepsy and reduces the expression of pro-epileptogenic factors in human cultured astrocytes

Temporal lobe epilepsy (TLE) is a chronic neurological disease in humans, which is refractory to pharmacological treatment in about 30% of the patients. Reactive glial cells are thought to play a major role during the development of epilepsy (epileptogenesis) via regulation of brain inflammation and remodeling of the extracellular matrix (ECM). These processes can be regulated by microRNAs (miRs), a class of small non‐coding RNAs, which can control entire gene networks at a post‐transcriptional level. The expression of miRs is known to change dynamically during epileptogenesis. miR‐132 is one of the most commonly upregulated miRs in animal TLE models with important roles shown in neurons. However, the possible role of miR‐132 in glia remains largely unknown. The aim of this study was to characterize the cell‐type specific expression of miR‐132 in the hippocampus of patients with TLE and during epileptogenesis in a rat TLE model. Furthermore, the potential role of miR‐132 was investigated by transfection of human primary cultured astrocytes that were stimulated with the cytokines IL‐1β or TGF‐β1. We showed an increased expression of miR‐132 in the human and rat epileptogenic hippocampus, particularly in glial cells. Transfection of miR‐132 in human primary astrocytes reduced the expression of pro‐epileptogenic COX‐2, IL‐1β, TGF‐β2, CCL2, and MMP3. This suggests that miR‐132, particularly in astrocytes, represents a potential therapeutic target that warrants further in vivo investigation.