Modulation of miR-146a/complement factor H-mediated inflammatory responses in a rat model of temporal lobe epilepsy

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.

Exploring the involvement of the alternative complement pathway in non-infectious uveitis pathogenesis

Purpose

Non-infectious uveitis is a complex disease characterized by intraocular inflammation of the uveal area and the leading cause of vision impairment and blindness in young people globally. However, what triggers inflammation and contributes to its recurrence remains unclear. The complement system has been linked to various immunological and inflammatory conditions. In the present study, we have systematically evaluated the role of the alternative complement pathway in the pathogenesis of non-infectious uveitis.

Methodology

Quantitative PCR was done in the peripheral leukocytes to study the expression of genes and regulatory miRNA in both anterior and posterior uveitis (n=28 in each category). Multiplex ELISA was performed to measure alternative pathway complement components, such as C3b, factor B, and CFH, and aqueous humor of infectious and non-infectious uveitis patients and non-inflammatory controls (n=10 each). Western blotting was done to validate the ELISA findings in a subset of patients and controls.

Results

Downregulation of C3 and CFH mRNA in the peripheral blood was shown by quantitative PCR in the group of anterior uveiits (AU), while the opposite result was found in the group of posterior uveitis (PU). ELISA levels of C3b and CFH proteins were significantly higher in aqueous humor of infectious and non-infectious uveitis (*p = 0.03 and **p = 0.0007 respectively) as compared to the control group. Western blotting further validated (VitH) the activation of the complement cascade in the aqueous (AH) and vitreous humor of patients with non-infectious uveitis, with an increased level of C3b (n=6) and CFH (n=4) in aqueous humor. C3b level was significantly increased while CFH was reduced relative to controls in the vitreous humor (VitH) of posterior uveitis patients compared to controls (n=27 in each category). A C3b to CFH ratio was computed to assess the regulation of complement activation and this index was several folds higher in both anterior and posterior uveitis (n=10 each). The expression of miRNA-hsa-miR-146a and miRNA-hsa-miR-155-5p that regulates CFH was downregulated and nicely correlated with the increased complement proteins in both anterior and posterior uveitis (n=10 each).

Conclusion

Our results demonstrate a clear role of CFH and the activation of the alternative complement pathway in the pathogenesis of non-infectious uveitis; however, its therapeutic potential warrants further investigations.

RNA therapeutics for epilepsy: An emerging modality for drug discovery

Drug discovery in epilepsy began with the finding of potassium bromide by Sir Charles Locock in 1857. The following century witnessed the introduction of phenotypic screening tests for discovering antiseizure medications (ASMs). Despite the high success rate of developing ASMs, they have so far failed in eliminating drug resistance and in delivering disease-modifying treatments. This emphasizes the need for new drug discovery strategies in epilepsy. RNA-based drugs have recently shown promise as a new modality with the potential of providing disease modification and counteracting drug resistance in epilepsy. RNA therapeutics can be directed either toward noncoding RNAs, such as microRNAs, long noncoding RNAs (ncRNAs), and circular RNAs, or toward messenger RNAs. The former show promise in sporadic, nongenetic epilepsies, as interference with ncRNAs allows for modulation of entire disease pathways, whereas the latter seem more promising in monogenic childhood epilepsies. Here, we describe therapeutic strategies for modulating disease-associated RNA molecules and highlight the potential of RNA therapeutics for the treatment of different patient populations such as sporadic, drug-resistant epilepsy, and childhood monogenic epilepsies.

MicroRNA-335-5p suppresses voltage-gated sodium channel expression and may be a target for seizure control

There remains an urgent need for new therapies for treatment-resistant epilepsy. Sodium channel blockers are effective for seizure control in common forms of epilepsy, but loss of sodium channel function underlies some genetic forms of epilepsy. Approaches that provide bidirectional control of sodium channel expression are needed. MicroRNAs (miRNA) are small noncoding RNAs which negatively regulate gene expression. Here we show that genome-wide miRNA screening of hippocampal tissue from a rat epilepsy model, mice treated with the antiseizure medicine cannabidiol, and plasma from patients with treatment-resistant epilepsy, converge on a single target-miR-335-5p. Pathway analysis on predicted and validated miR-335-5p targets identified multiple voltage-gated sodium channels (VGSCs). Intracerebroventricular injection of antisense oligonucleotides against miR-335-5p resulted in upregulation of Scn1a, Scn2a, and Scn3a in the mouse brain and an increased action potential rising phase and greater excitability of hippocampal pyramidal neurons in brain slice recordings, consistent with VGSCs as functional targets of miR-335-5p. Blocking miR-335-5p also increased voltage-gated sodium currents and SCN1A, SCN2A, and SCN3A expression in human induced pluripotent stem cell-derived neurons. Inhibition of miR-335-5p increased susceptibility to tonic-clonic seizures in the pentylenetetrazol seizure model, whereas adeno-associated virus 9-mediated overexpression of miR-335-5p reduced seizure severity and improved survival. These studies suggest modulation of miR-335-5p may be a means to regulate VGSCs and affect neuronal excitability and seizures. Changes to miR-335-5p may reflect compensatory mechanisms to control excitability and could provide biomarker or therapeutic strategies for different types of treatment-resistant epilepsy.

Dysregulation of miR-146a: a causative factor in epilepsy pathogenesis, diagnosis, and prognosis

miR-146a is an NF-κB-dependent miRNA that acts as an anti-inflammatory miRNA via the Toll-like receptor (TLR) pathway. miR-146a targets multiple genes and has been identified to directly or indirectly regulate processes other than inflammation, including intracellular Ca changes, apoptosis, oxidative stress, and neurodegeneration. miR-146a is an important regulator of gene expression in epilepsy development and progression. Furthermore, miR-146a-related single nucleotide polymorphisms (SNPs) and single nucleotide variants (SNVs) contribute to the genetic susceptibility to drug resistance and seizure severity in epilepsy patients. This study summarizes the abnormal expression patterns of miR-146a in different types and stages of epilepsy and its potential molecular regulation mechanism, indicating that miR-146a can be used as a novel biomarker for epilepsy diagnosis, prognosis, and treatment.

Exosomal noncoding RNAs in central nervous system diseases: biological functions and potential clinical applications

Central nervous system (CNS) disease is a general term for a series of complex and diverse diseases, including Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS), CNS tumors, stroke, epilepsy, and amyotrophic lateral sclerosis (ALS). Interneuron and neuron-glia cells communicate with each other through their homeostatic microenvironment. Exosomes in the microenvironment have crucial impacts on interneuron and neuron-glia cells by transferring their contents, such as proteins, lipids, and ncRNAs, constituting a novel form of cell-to-cell interaction and communication. Exosomal noncoding RNAs (ncRNAs), including microRNAs (miRNAs), long noncoding RNAs (lncRNAs), circular RNAs (circRNAs), and PIWI-interacting RNAs (piRNAs), regulate physiological functions and maintain CNS homeostasis. Exosomes are regarded as extracellular messengers that transfer ncRNAs between neurons and body fluids due to their ability to cross the blood-brain barrier. This review aims to summarize the current understanding of exosomal ncRNAs in CNS diseases, including prospective diagnostic biomarkers, pathological regulators, therapeutic strategies and clinical applications. We also provide an all-sided discussion of the comparison with some similar CNS diseases and the main limitations and challenges for exosomal ncRNAs in clinical applications.

Non-Coding RNAs: New Biomarkers and Therapeutic Targets for Temporal Lobe Epilepsy

Temporal lobe epilepsy (TLE) is the most common form of focal epilepsy; it is considered a network disorder associated with structural changes. Incomplete knowledge of the pathological changes in TLE complicates a therapeutic approach; indeed, 30 to 50% of patients with TLE are refractory to drug treatment. Non-coding RNAs (ncRNAs), acting as epigenetic factors, participate in the regulation of the pathophysiological processes of epilepsy and are dysregulated during epileptogenesis. Abnormal expression of ncRNA is observed in patients with epilepsy and in animal models of epilepsy. Furthermore, ncRNAs could also be used as biomarkers for the diagnosis and prognosis of treatment response in epilepsy. In summary, ncRNAs can represent important mechanisms and targets for the modulation of brain excitability and can provide information on pathomechanisms, biomarkers and novel therapies for epilepsy. In this review, we summarize the latest research advances concerning mainly molecular mechanisms, regulated by ncRNA, such as synaptic plasticity, inflammation and apoptosis, already associated with the pathogenesis of TLE. Moreover, we discuss the role of ncRNAs, such as microRNAs, long non-coding RNAs and circular RNAs, in the pathophysiology of epilepsy, highlighting their use as potential biomarkers for future therapeutic approaches.

Screening of prototype antiseizure and anti-inflammatory compounds in the Theiler's murine encephalomyelitis virus model of epilepsy

OBJECTIVE

Infection with Theiler's murine encephalomyelitis virus (TMEV) in C57Bl/6J mice results in handling-induced seizures and is useful for evaluating compounds effective against infection-induced seizures. However, to date only a few compounds have been evaluated in this model, and a comprehensive study of antiseizure medications (ASMs) has not yet been performed. Furthermore, as the TMEV infection produces marked neuroinflammation, an evaluation of prototype anti-inflammatory compounds is needed as well.

METHODS

Male C57Bl/6J mice were inoculated with TMEV (day 0) followed by daily administrations of test compounds (day 3-7) and subsequent handling sessions (day 3-7). Doses of ASMs, comprising several mechanistic classes, were selected based on previously published data demonstrating the effect of these compounds in reducing seizures in the 6 Hz model of pharmacoresistant seizures. Doses of anti-inflammatory compounds, comprising several mechanistic classes, were selected based on published evidence of reduction of inflammation or inflammation-related endpoints.

RESULTS

Several prototype ASMs reduced acute seizures following TMEV infection: lacosamide, phenytoin, ezogabine, phenobarbital, tiagabine, gabapentin, levetiracetam, topiramate, and sodium valproate. Of these, phenobarbital and sodium valproate had the greatest effect (>95% seizure burden reduction). Prototype anti-inflammatory drugs celecoxib, dexamethasone, and prednisone also moderately reduced seizure burden.

SIGNIFICANCE

The TMEV model is utilized by the Epilepsy Therapy Screening Program (ETSP) as a tool for evaluation of novel compounds. Compounds reducing seizures in the TMEV comprise distinct mechanistic classes, some with mechanisms of action that extend beyond traditional ASMs.

An Emerging Role of miRNAs in Neurodegenerative Diseases: Mechanisms and Perspectives on miR146a

Significance: Advancements in and access to health care have led to unprecedented improvements in the quality of life and increased lifespan of human beings in the past century. However, aging is a significant risk factor for neurodegenerative diseases (NDs). Hence, improved life expectancy has led to an increased incidence of NDs. Despite intense research, effective treatments for NDs remain elusive. The future of neurotherapeutics development depends on effective disease modification strategies centered on carefully scrutinized targets. Recent Advances: As a promising new direction, recent evidence has demonstrated that epigenetic processes modify diverse biochemical pathways, including those related to NDs. Small non-coding RNAs, known as microRNAs (miRNAs), are components of the epigenetic system that alter the expression of target genes at the post-transcriptional level. Critical Issues: miRNAs are expressed abundantly in the central nervous system and are critical for the normal functioning and survival of neurons. Here, we review recent advances in elucidating miRNAs' roles in NDs and discuss their potential as therapeutic targets. In particular, neuroinflammation is a major pathological hallmark of NDs and miR146a is a crucial regulator of inflammation. Future Directions: Finally, we explore the possibilities of developing miR146a as a potential biomarker and therapeutic target where additional research may help facilitate the detection and amelioration of neuroinflammation in NDs. Antioxid. Redox Signal. 35, 580-594.

microRNA-146a-5p, Neurotropic Viral Infection and Prion Disease (PrD)

The human brain and central nervous system (CNS) harbor a select sub-group of potentially pathogenic microRNAs (miRNAs), including a well-characterized NF-kB-sensitive Homo sapiens microRNA hsa-miRNA-146a-5p (miRNA-146a). miRNA-146a is significantly over-expressed in progressive and often lethal viral- and prion-mediated and related neurological syndromes associated with progressive inflammatory neurodegeneration. These include ~18 different viral-induced encephalopathies for which data are available, at least ~10 known prion diseases (PrD) of animals and humans, Alzheimer’s disease (AD) and other sporadic and progressive age-related neurological disorders. Despite the apparent lack of nucleic acids in prions, both DNA- and RNA-containing viruses along with prions significantly induce miRNA-146a in the infected host, but whether this represents part of the host’s adaptive immunity, innate-immune response or a mechanism to enable the invading prion or virus a successful infection is not well understood. Current findings suggest an early and highly interactive role for miRNA-146a: (i) as a major small noncoding RNA (sncRNA) regulator of innate-immune responses and inflammatory signaling in cells of the human brain and CNS; (ii) as a critical component of the complement system and immune-related neurological dysfunction; (iii) as an inducible sncRNA of the brain and CNS that lies at a critical intersection of several important neurobiological adaptive immune response processes with highly interactive associations involving complement factor H (CFH), Toll-like receptor pathways, the innate-immunity, cytokine production, apoptosis and neural cell decline; and (iv) as a potential biomarker for viral infection, TSE and AD and other neurological diseases in both animals and humans. In this report, we review the recent data supporting the idea that miRNA-146a may represent a novel and unique sncRNA-based biomarker for inflammatory neurodegeneration in multiple species. This paper further reviews the current state of knowledge regarding the nature and mechanism of miRNA-146a in viral and prion infection of the human brain and CNS with reference to AD wherever possible.

Aberrant Complement System Activation in Neurological Disorders

The complement system is an assembly of proteins that collectively participate in the functions of the healthy and diseased brain. The complement system plays an important role in the maintenance of uninjured (healthy) brain homeostasis, contributing to the clearance of invading pathogens and apoptotic cells, and limiting the inflammatory immune response. However, overactivation or underregulation of the entire complement cascade within the brain may lead to neuronal damage and disturbances in brain function. During the last decade, there has been a growing interest in the role that this cascading pathway plays in the neuropathology of a diverse array of brain disorders (e.g., acute neurotraumatic insult, chronic neurodegenerative diseases, and psychiatric disturbances) in which interruption of neuronal homeostasis triggers complement activation. Dysfunction of the complement promotes a disease-specific response that may have either beneficial or detrimental effects. Despite recent advances, the explicit link between complement component regulation and brain disorders remains unclear. Therefore, a comprehensible understanding of such relationships at different stages of diseases could provide new insight into potential therapeutic targets to ameliorate or slow progression of currently intractable disorders in the nervous system. Hence, the aim of this review is to provide a summary of the literature on the emerging role of the complement system in certain brain disorders.

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.

MicroRNAs and target genes in epileptogenesis

Epilepsy is a chronic brain dysfunction. Current antiepileptic medicines cannot prevent epileptogenesis. Increasing data have shown that microRNAs (miRNAs) are selectively altered within the epileptic hippocampi of experimental models and human tissues, and these alterations affect the genes that control epileptogenesis. Furthermore, manipulation of miRNAs in animal models can modify epileptogenesis. As a result, miRNAs have been proposed as promising targets for treating epilepsy. We searched PubMed using the terms "microRNAs/miRNAs AND epilepsy", "microRNAs/miRNAs AND epileptogenesis", and "microRNAs/miRNAs AND seizure". We selected the articles in which the relationship between miRNAs and target gene(s) was validated and manipulation of miRNAs in in vivo epilepsy models modified epileptogenesis during the chronic phase via gene regulation. A total of 13 miRNAs were found in the present review. Based on the current analysis of miRNAs and their target gene(s), each miRNA has limitations as a potential epilepsy target. Importantly, miR-211 or miR-128 transgenic mice displayed seizures. These findings highlight new developments for epileptogenesis prevention. Developing novel strategies to modify epileptogenesis will be effective in curing epilepsy patients. This article provides an overview of the clinical application of miRNAs as novel targets for epilepsy.

Influence of different erythrocyte storage times on the macrophage response in haemorrhagic shock mice

Objective

To investigate the characteristics of the macrophage response to transfusion of erythrocytes kept at different storage times in the mouse model of haemorrhagic shock.

Methods

Erythrocytes were isolated from mice and stored for 7, 21 or 35 days and samples injected intravenously into haemorrhagic shock mice. Changes in macrophages, inflammatory cytokines and T cell differentiation were assessed using flow cytometry or enzyme-linked immunosorbent assay (ELISA). In a second experiment, haemorrhagic shock mice were injected with 21D-erythrocytes and the expression of nuclear factor erythroid 2 p45-related factor 2 (Nrf2), arginine -1 (Arg-1) and inducible nitrous oxide (iNOS) determined.

Results

The proportion of M1-polarized macrophages was greatest in the 21D group while M2 macrophages tended to increase with the erythrocyte storage time. Levels of inflammatory cytokines and T helper 1 (Th1) cells increased in proportion to erythrocytes storage time. Most regulatory T cells (Treg) were found at 21D. Arg-1 expression was significantly increased in a group that received an heme oxygenase 1 (HO-1) agonist and significantly decreased in a group that received an HO-1 inhibitor but there were no differences in the expression of iNOS or Nrf2.

Conclusion

21D storage time may be an important time point for erythrocyte storage and immunity response and Arg-1 may have a role in the macrophage response to erythrocyte infusion.

microRNA-146a Signaling in Alzheimer's Disease (AD) and Prion Disease (PrD)

The mouse- and human-brain-resident, nuclear factor kappa B (NF-κB)-regulated, micro RNA-146a-5p (miRNA-146a-5p) is an inducible, 22-nucleotide, single-stranded non-coding RNA (sncRNA) easily detected in several brain and immunological cell types, and an important epigenetic modulator of inflammatory signaling and the innate-immune response in several neurological disorders. Among all studied microRNAs, miRNA-146a-5p (typically referred to as just miRNA-146a) has been well characterized and its pathological function in progressive, age-related, and lethal human inflammatory neurodegenerative disease states is well documented. This communication will review our current understanding of miRNA-146a, its induction by the NF-kB-stimulating actions of inflammatory mediators, including the secretory products of certain microbial species such as viral vectors, and Gram-negative bacteria (such as Bacteroides fragilis) that are normal residents of the human gastrointestinal (GI) tract microbiome, and how miRNA-146a appears to contribute to neuro-pathological, neuro-inflammatory, and altered neuro-immunological aspects of both Alzheimer's disease (AD) and prion disease (PrD).

Loss of the neurodevelopmental disease-associated gene miR-146a impairs neural progenitor differentiation and causes learning and memory deficits

BACKGROUND

Formation and maintenance of appropriate neural networks require tight regulation of neural stem cell proliferation, differentiation, and neurogenesis. microRNAs (miRNAs) play an important role in brain development and plasticity, and dysregulated miRNA profiles have been linked to neurodevelopmental disorders including autism, schizophrenia, or intellectual disability. Yet, the functional role of miRNAs in neural development and postnatal brain functions remains unclear.

METHODS

Using a combination of cell biology techniques as well as behavioral studies and brain imaging, we characterize mouse models with either constitutive inactivation or selectively hippocampal knockdown of the neurodevelopmental disease-associated gene Mir146a, the most commonly deregulated miRNA in developmental brain disorders (DBD).

RESULTS

We first show that during development, loss of miR-146a impairs the differentiation of radial glial cells, neurogenesis process, and neurite extension. In the mouse adult brain, loss of miR-146a correlates with an increased hippocampal asymmetry coupled with defects in spatial learning and memory performances. Moreover, selective hippocampal downregulation of miR-146a in adult mice causes severe hippocampal-dependent memory impairments indicating for the first time a role for this miRNA in postnatal brain functions.

CONCLUSION

Our results show that miR-146a expression is critical for correct differentiation of neural stem cell during brain development and provide for the first time a strong argument for a postnatal role of miR-146a in regulating hippocampal-dependent memory. Furthermore, the demonstration that the Mir146a-/- mouse recapitulates several aspects reported in DBD patients, including impaired neurogenesis, abnormal brain anatomy, and working and spatial memories deficits, provides convincing evidence that the dysregulation of miR146a contributes to the pathogenesis of DBDs.

Circulating microRNAs as potential biomarkers for genetic generalized epilepsies: a three microRNA panel

BACKGROUND AND PURPOSE

Genetic generalized epilepsies (GGEs) encompass a group of syndromes of mainly genetic causes, characterized by the involvement of both hemispheres. MicroRNAs (miRNAs) are small non-coding RNAs with a critical role in the regulation of neuronal biological processes through gene expression modulation. Dysregulated miRNA expression has been shown in epilepsy. Due to their stability in biological fluids like serum, miRNAs have assumed a prominent role in biomarker research. Our aim was to evaluate circulating levels of three miRNAs in GGE patients and assess their putative diagnostic value.

METHODS

MiR-146a, miR-155 and miR-132 were quantified by real-time polymerase chain reaction in the serum of 79 GGE patients (47 women, 32 men, 35.1 ± 12.4 years) and 67 healthy individuals (41 women, 26 men, 42.4 ± 10.1 years). Relative expression values were calculated using the 2^-ΔΔCt method. Receiver operating characteristic curve analysis was performed to assess diagnostic value. MiRNA expression was correlated with clinicopathological features.

RESULTS

Serum levels of miR-146a and miR-155 were significantly upregulated in GGE patients relative to controls (3.13 and 6.05, respectively). Combined miR-146a, miR-155 and miR-132 serum levels performed well as a diagnostic biomarker, discriminating GGE patients from controls with an area under the curve of 0.85, 80% specificity and 73% sensitivity.

CONCLUSIONS

Our results indicate that miR-146a, miR-155 and miR-132 may partake in GGE epileptogenesis. A panel of three circulating miRNAs with potential value as a GGE biomarker is reported for the first time. Novel biomarkers may help to identify new treatment targets and contribute to improved patients' quality of life through earlier diagnosis and a more precise prognosis.

Associations of microRNAs, Angiogenesis-Regulating Factors and CFH Y402H Polymorphism-An Attempt to Search for Systemic Biomarkers in Age-Related Macular Degeneration

Age-related macular degeneration (AMD) remains the leading cause of blindness in elderly people, but the pathophysiology of this disease is still largely unknown. We investigated the systemic expression of angiogenesis-regulating growth factors and selected miRNAs known to regulate angiogenesis in AMD patients. We also focused on possible correlations of their expression with the presence of CFH Y402H or ARMS A69S risk variants. A total of 354 AMD patients and 121 controls were enrolled in this study. The levels of angiogenesis-regulating factors were analyzed in plasma samples using Luminex technology. The expression of selected miRNAs was analyzed in peripheral blood plasma using real-time qPCR. The genetic analysis was performed with an Illumina NextSeq500 system. AMD was an independent factor associated with lower levels of angiogenin (β = −0.29, p < 0.001), endostatin (β = −0.18, p < 0.001), FGF-basic (β = −0.18, p < 0.001), PlGF (β = −0.24, p < 0.001), miRNA-21-3p (β = −0.13, p = 0.01) and miRNA-155-5p (β = −0.16, p = 0.002); and with higher levels of FGF-acidic (β = 0.11, p = 0.03), miRNA-23a-3p (β = 0.17, p < 0.001), miRNA-126-5p (β = 0.13, p = 0.009), miRNA-16-5p (β = 0.40, p < 0.001), miRNA-17-3p (β = 0.13, p = 0.01), miRNA-17-5p (β = 0.17, p < 0.001), miRNA-223-3p (β = 0.15, p = 0.004), and miRNA-93 (β = 0.11, p = 0.04). The expression of analyzed miRNA molecules significantly correlated with the levels of tested angiogenesis-regulating factors and clinical parameters in AMD patients, whereas such correlations were not observed in controls. We also found an association between the CFH Y402H polymorphism and miRNA profiles, whereby TT homozygotes showed evidently higher expression of miRNA-16-5p than CC homozygotes or TC heterozygotes (p = 0.0007). Our results suggest that the balance between systemic pro- and anti-angiogenic factors and miRNAs is vital in multifactorial AMD pathogenesis.

Catalpol Exerts an Anti-Epilepticus Effect, Possibly by Regulating the Nrf2-Keap1-ARE Signaling Pathway

Background

Status epilepticus (SE) is a refractory neurological disease with high mortality and morbidity rates. SE can be induced by numerous factors, including oxidative stress. Catalpol has several biological activities, including regulating the oxidative stress response. However, the role of catapol in SE has not been fully elucidated.

Material/Methods

Thirty Wistar rats were randomly and equally divided into 3 groups: a control group, an SE group established by LiCl-pilocarpine intraperitoneal injection, and an SE+catalpol group established administering catalpol to SE rats. Epileptic seizure level and after-discharge duration (ADD) were analyzed. Cognitive function was assessed by Morris water maze. Myeloperoxidase (MPO) and superoxide dismutase (SOD) activities were tested. Keap1 and ARE mRNA expressions were detected by real-time PCR. Nrf2 protein expression was determined by Western blot.

Results

Catalpol significantly decreased epileptic seizure level, extended ADD, and improved cognitive function compared with the SE group (P<0.05). MPO was increased, SOD was reduced, Keap1 mRNA was upregulated, and Nrf2 protein and ARE mRNA were reduced in the SE group compared with the control group (P<0.05). Catalpol markedly decreased MPO, enhanced SOD activity, decreased Keap1 mRNA level, and elevated Nrf2 protein and ARE mRNA expressions compared with the SE group (P<0.05).

Conclusions

Catalpol plays an anti-epileptic role and improves cognitive function by regulating the Nrf2-Keap1-ARE signaling pathway to inhibit oxidative stress response.

Potential Role of miRNAs as Theranostic Biomarkers of Epilepsy

Epilepsy includes a group of disorders of the brain characterized by an enduring predisposition to generate epileptic seizures. Although familial epilepsy has a genetic component and heritability, the etiology of the majority of non-familial epilepsies has no known associated genetic mutations. In epilepsy, recent epigenetic profiles have highlighted a possible role of microRNAs in its pathophysiology. In particular, molecular profiling identifies a significant number of microRNAs (miRNAs) altered in epileptic hippocampus of both animal models and human tissues. In this review, analyzing molecular profiles of different animal models of epilepsy, we identified a group of 20 miRNAs commonly altered in different epilepsy-animal models. As emerging evidences highlighted the poor overlap between signatures of animal model tissues and human samples, we focused our analysis on miRNAs, circulating in human biofluids, with a principal role in epilepsy hallmarks, and we identified a group of 8 diagnostic circulating miRNAs. We discussed the functional role of these 8 miRNAs in the epilepsy hallmarks. A few of them have also been proposed as therapeutic molecules for epilepsy treatment, revealing a great potential for miRNAs as theranostic molecules in epilepsy.

Role of miR-146a in neural stem cell differentiation and neural lineage determination: relevance for neurodevelopmental disorders

Background

MicroRNAs (miRNAs) are small, non-coding RNAs that regulate gene expression at the post-transcriptional level. miRNAs have emerged as important modulators of brain development and neuronal function and are implicated in several neurological diseases. Previous studies found miR-146a upregulation is the most common miRNA deregulation event in neurodevelopmental disorders such as autism spectrum disorder (ASD), epilepsy, and intellectual disability (ID). Yet, how miR-146a upregulation affects the developing fetal brain remains unclear.

Methods

We analyzed the expression of miR-146a in the temporal lobe of ASD children using Taqman assay. To assess the role of miR-146a in early brain development, we generated and characterized stably induced H9 human neural stem cell (H9 hNSC) overexpressing miR-146a using various cell and molecular biology techniques.

Results

We first showed that miR-146a upregulation occurs early during childhood in the ASD brain. In H9 hNSC, miR-146a overexpression enhances neurite outgrowth and branching and favors differentiation into neuronal like cells. Expression analyses revealed that 10% of the transcriptome was deregulated and organized into two modules critical for cell cycle control and neuronal differentiation. Twenty known or predicted targets of miR-146a were significantly deregulated in the modules, acting as potential drivers. The two modules also display distinct transcription profiles during human brain development, affecting regions relevant for ASD including the neocortex, amygdala, and hippocampus. Cell type analyses indicate markers for pyramidal, and interneurons are highly enriched in the deregulated gene list. Up to 40% of known markers of newly defined neuronal lineages were deregulated, suggesting that miR-146a could participate also in the acquisition of neuronal identities.

Conclusion

Our results demonstrate the dynamic roles of miR-146a in early neuronal development and provide new insight into the molecular events that link miR-146a overexpression to impaired neurodevelopment. This, in turn, may yield new therapeutic targets and strategies.

Electronic supplementary material

The online version of this article (10.1186/s13229-018-0219-3) contains supplementary material, which is available to authorized users.

Targeting of microRNA-21-5p protects against seizure damage in a kainic acid-induced status epilepticus model via PTEN-mTOR

OBJECTIVE

Studies have shown that microRNAs play a role in the development of epilepsy by regulating downstream target messenger (m)RNA. The present study aims to determine the changes associated with microRNA-21-5p (miR-21-5p) during epileptogenesis in a kainic acid rat model, and to assess whether the PTEN-mTOR pathway is a target of miR-21-5p.

METHOD

Reverse transcription polymerase chain reaction (RT-PCR) was used to examine the quantitative expressions of miR-21-5p and PTEN, and Western blotting was used to test the activity of mTOR in the acute, latent, and chronic stages of epileptogenesis. The antagomir of miR-21-5p was injected into the intracerebroventricular space using a microsyringe. Neuronal death and epilepsy discharge were assessed by Nissl staining and electroencephalography (EEG), respectively. The Morris water maze (MWM) was used to assess the cognitive impairment in rats after status epilepticus (SE).

RESULTS

Both miR-21-5p and mTOR were upregulated and PTEN was downregulated in rats during acute, latent, and chronic stages of epileptogenesis when compared with those of the control. After using antagomir miR-21-5p in vivo, miR-21-5p and mTOR decreased and the expression of PTEN increased compared with that in the SE model. The silencing of miR-21-5p diminished the number of abnormal spikes on EEG and decreased the number of neuron deletions on Nissl staining. The cognitive and memory impairment caused by epilepsy could also be improved after miR-21-5p knockdown in vivo.

CONCLUSION

The results of the present study demonstrate that PTEN-mTOR is the target of miR-21-5p in a kainic acid model of epilepsy. The knockout of miR-21-5p decreases the neuronal damage in stages of epileptogenesis. The miR-21-5p/PTEN/mTOR axis may be a potential target for preventing and treating seizures and epileptic damage.

The role of the microRNA-146a/complement factor H/interleukin-1β-mediated inflammatory loop circuit in the perpetuate inflammation of chronic temporal lobe epilepsy

Increasing evidence indicates that neuroinflammation plays a crucial role in the pathogenesis of temporal lobe epilepsy (TLE). However, it is unclear how the perpetuate inflammation develops. Some recent studies have suggested the possible involvement of microRNA-146a (miR-146a) in the modulation of inflammatory signaling occurring in TLE. To understand how miR-146a modulates inflammatory signaling in TLE, we investigated the role of interleukin-1β (IL-1β), miR-146a and human complement factor H (CFH) in the perpetuate inflammation in rat models of chronic TLE and U251 cells. We found that enhancive miR-146a could upregulate the expression of IL-1β and downregulate the expression of CFH, whereas reductive miR-146a could downregulate the expression of IL-1β and upregulate the expression of CFH, in hippocampi of chronic TLE rat models. Meanwhile, enhancive miR-146a could increase the abnormal wave forms in the chronic TLE rat models. Additionally, enhancive IL-1β could feedback downregulate the expression of CFH, upregulate the expression of miR-146a and increase the abnormal wave forms in chronic TLE rat models. After CFH gene knockdown in U251 cells, enhancive miR-146a did not upregulate the expression of IL-1β. In summary, this study shows that enhancive miR-146a can upregulate the inflammatory factor IL-1β in chronic TLE by downregulating CFH, and that upregulation of IL-1β plays an important feedback-regulating role in the expression of miR-146a and CFH, forming a miR-146a–CFH–IL-1β loop circuit that initiates a cascade of inflammation and then leads to the perpetuate inflammation in TLE. Therefore, modulation of the miR-146a–CFH–IL-1β loop circuit could be a novel therapeutic target for TLE.

Summary: The microRNA-146a–complement factor H–interleukin-1β loop circuit might initiate a cascade of inflammation, leading to the perpetuate inflammation in temporal lobe epilepsy.

Experimental Demyelination and Axonal Loss Are Reduced in MicroRNA-146a Deficient Mice

Background

The cuprizone (CPZ) model of multiple sclerosis (MS) was used to identify microRNAs (miRNAs) related to in vivo de- and remyelination. We further investigated the role of miR-146a in miR-146a-deficient (KO) mice: this miRNA is differentially expressed in MS lesions and promotes differentiation of oligodendrocyte precursor cells (OPCs) during remyelination, but its role has not been examined during demyelination.

Methods

MicroRNAs were examined by Agilent Mouse miRNA Microarray in the corpus callosum during CPZ-induced demyelination and remyelination. Demyelination, axonal loss, changes in number of oligodendrocytes, OPCs, and macrophages/microglia was compared by histology/immunohistochemistry between KO and WT mice. Differential expression of target genes and proteins of miR-146a was analyzed in the transcriptome (4 × 44K Agilent Whole Mouse Genome Microarray) and proteome (liquid chromatography tandem mass spectrometry) of CPZ-induced de- and remyelination in WT mice. Levels of proinflammatory molecules in the corpus callosum were compared in WT versus KO mice by Meso Scale Discovery multiplex protein analysis.

Results

miR-146a was increasingly upregulated during CPZ-induced de- and remyelination. The absence of miR-146a in KO mice protected against demyelination, axonal loss, body weight loss, and atrophy of thymus and spleen. The number of CNP⁺ oligodendrocytes was increased during demyelination in the miR-146a KO mice, while there was a trend of increased number of NG2⁺ OPCs in the WT mice. miR-146a target genes, SNAP25 and SMAD4, were downregulated in the proteome of demyelinating corpus callosum in WT mice. Higher levels of SNAP25 were measured by ELISA in the corpus callosum of miR-146a KO mice, but there was no difference between KO and WT mice during demyelination. Multiplex protein analysis of the corpus callosum lysate revealed upregulated TNF-RI, TNF-RII, and CCL2 in the WT mice in contrast to KO mice. The number of Mac3⁺ and Iba1⁺ macrophages/microglia was reduced in the demyelinating corpus callosum of the KO mice.

Conclusion

During demyelination, absence of miR-146a reduced inflammatory responses, demyelination, axonal loss, the number of infiltrating macrophages, and increased the number of myelinating oligodendrocytes. The number of OPCs was slightly higher in the WT mice during remyelination, indicating a complex role of miR-146a during in vivo de- and remyelination.

Function of miR-146a-5p in Tumor Cells As a Regulatory Switch between Cell Death and Angiogenesis: Macrophage Therapy Revisited

Tumors survive and progress by evading killing mechanisms of the immune system, and by generating a tumor microenvironment (TME) that reprograms macrophages in situ to produce factors that support tumor growth, angiogenesis, and metastasis. We have previously shown that by blocking the translation of the enzyme inducible nitric oxide synthase (iNOS), miR-146a-5p inhibits nitric oxide (NO) production in a mouse renal carcinoma cell line (RENCA), thereby endowing RENCA cells with resistance to macrophage-induced cell death. Here, we expand these findings to the mouse colon carcinoma CT26 cell line and demonstrate that neutralizing miR-146a-5p's activity by transfecting both RENCA and CT26 cells with its antagomir restored iNOS expression and NO production and enhanced susceptibility to macrophage-induced cell death (by 48 and 25%, respectively, p < 0.001). Moreover, miR-146a-5p suppression simultaneously inhibited the expression of the pro-angiogenic protein EMMPRIN (threefolds, p < 0.001), leading to reduced MMP-9 and vascular endothelial growth factor secretion (twofolds and threefolds, respectively, p < 0.05), and reduced angiogenesis, as estimated by in vitro tube formation and scratch assays. When we injected tumors with pro-inflammatory-stimulated RAW 264.7 macrophages together with i.v. injection of the miR-146a-5p antagomir, we found inhibited tumor growth (sixfolds, p < 0.001) and angiogenesis (twofolds, p < 0.01), and increased apoptosis (twofolds, p < 0.01). This combination therapy increased nitrites and reduced TGFβ concentrations in tumor lysates, alleviated immune suppression, and allowed enhanced infiltration of cytotoxic CD8⁺ T cells. Thus, miR-146a-5p functions as a control switch between angiogenesis and cell death, and its neutralization can manipulate the crosstalk between tumor cells and macrophages and profoundly change the TME. This strategy can be therapeutically utilized in combination with the macrophage therapy approach to induce the immune system to successfully attack the tumor, and should be further explored as a new therapy for the treatment of cancer.

MicroRNA-induced silencing in epilepsy: Opportunities and challenges for clinical application

MicroRNAs are master regulators of gene expression. Single microRNAs influence multiple proteins within diverse molecular pathways and networks. Therefore, changes in levels or activity of microRNAs can have profound effects on cellular function. This makes dysregulated microRNA-induced silencing an attractive potential disease mechanism in complex disorders like epilepsy, where numerous cellular pathways and processes are affected simultaneously. Indeed, several years of research in rodent models have provided strong evidence that acute or recurrent seizures change microRNA expression and function. Moreover, altered microRNA expression has been observed in brain and blood from patients with various epilepsy disorders, such as tuberous sclerosis. MicroRNAs can be easily manipulated using sense or antisense oligonucleotides, opening up opportunities for therapeutic intervention. Here, we summarize studies using these techniques to identify microRNAs that modulate seizure susceptibility, describe protein targets mediating some of these effects, and discuss cellular pathways, for example neuroinflammation, that are controlled by epilepsy-associated microRNAs. We critically assess current gaps in knowledge regarding target- and cell-specificity of microRNAs that have to be addressed before clinical application as therapeutic targets or biomarkers. The recent progress in understanding microRNA function in epilepsy has generated strong momentum to encourage in-depth mechanistic studies to develop microRNA-targeted therapies. Developmental Dynamics 247:94-110, 2018. © 2017 Wiley Periodicals, Inc.

Pathophysiology and Clinical Utility of Non-coding RNAs in Epilepsy

Epilepsy is a common neurologic disorder. The underlying pathological processes include synaptic strength, inflammation, ion channels, and apoptosis. Acting as epigenetic factors, non-coding RNAs (ncRNAs) participate in the regulation of pathophysiologic processes of epilepsy and are dysregulated during epileptogenesis. Aberrant expression of ncRNAs are observed in epilepsy patients and animal models of epilepsy. Furthermore, ncRNAs might also be used as biomarkers for diagnosis and the prognosis of treatment response in epilepsy. In this review, we will summarize the role of ncRNAs in the pathophysiology of epilepsy and the putative utilization of ncRNAs as diagnostic biomarkers and therapeutic targets.