Potent Anti-seizure Effects of Locked Nucleic Acid Antagomirs Targeting miR-134 in Multiple Mouse and Rat Models of Epilepsy

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

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

The role of miRNA134 in pathogenesis and treatment of intractable epilepsy: a review article

MicroRNA-134 (miRNA134) has emerged as a critical regulator in the pathogenesis of epilepsy, particularly in intractable cases resistant to conventional therapies. This review explores the multifaceted roles of miRNA134 in epileptogenesis, focusing on its influence on dendritic spine morphology and synaptic plasticity. Through its interactions with proteins such as LIM kinase 1 (LIMK1), Pumilio 2 (PUM2), and Tubby-like protein 1 (TULP1), miRNA134 modulates various molecular pathways implicated in epilepsy development. Preclinical studies have shown pro-mising results in targeting miRNA134 for mitigating seizure activity, highlighting its potential as a therapeutic target. Furthermore, miRNA134 holds promise as a biomarker for epilepsy diagnosis and prognosis, offering opportunities for personalized treatment approaches. However, further research is warranted to elucidate the precise mechanisms underlying miRNA134's effects and to translate these findings into clinical applications.

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.

MiR-324-5p inhibition after intrahippocampal kainic acid-induced status epilepticus does not prevent epileptogenesis in mice

Background

Acquired epilepsies are caused by an initial brain insult that is followed by epileptogenesis and finally the development of spontaneous recurrent seizures. The mechanisms underlying epileptogenesis are not fully understood. MicroRNAs regulate mRNA translation and stability and are frequently implicated in epilepsy. For example, antagonism of a specific microRNA, miR-324-5p, before brain insult and in a model of chronic epilepsy decreases seizure susceptibility and frequency, respectively. Here, we tested whether antagonism of miR-324-5p during epileptogenesis inhibits the development of epilepsy.

Methods

We used the intrahippocampal kainic acid (IHpKa) model to initiate epileptogenesis in male wild type C57BL/6 J mice aged 6-8 weeks. Twenty-four hours after IHpKa, we administered a miR-324-5p or scrambled control antagomir intracerebroventricularly and implanted cortical surface electrodes for EEG monitoring. EEG data was collected for 28 days and analyzed for seizure frequency and duration, interictal spike activity, and EEG power. Brains were collected for histological analysis.

Results

Histological analysis of brain tissue showed that IHpKa caused characteristic hippocampal damage in most mice regardless of treatment. Antagomir treatment did not affect latency to, frequency, or duration of spontaneous recurrent seizures or interictal spike activity but did alter the temporal development of frequency band-specific EEG power.

Conclusion

These results suggest that miR-324-5p inhibition during epileptogenesis induced by status epilepticus does not convey anti-epileptogenic effects despite having subtle effects on EEG frequency bands. Our results highlight the importance of timing of intervention across epilepsy development and suggest that miR-324-5p may act primarily as a proconvulsant rather than a pro-epileptogenic regulator.

Potentials of miR-9-5p in promoting epileptic seizure and improving survival of glioma patients

Background

Epilepsy affects over 70 million people worldwide; however, the underlying mechanisms remain unclear. MicroRNAs (miRNAs) have essential functions in epilepsy. miRNA-9, a brain-specific/enriched miRNA, plays a role in various nervous system diseases and tumors, but whether miRNA-9 is involved in epilepsy and glioma-associated epilepsy remains unknown. Therefore, we aimed to explore the potential role of miR-9-5p in seizures and its effect on the survival of glioma patients, in order to provide new targets for the treatment of epilepsy and glioma.

Methods

The YM500v2 database was used to validate the expression of hsa-miR-9-5p in tissues. Moreover, qRT-PCR was performed to investigate the expression of miR-9-5p in temporal lobe epilepsy patients and rats with lithium-pilocarpine-induced seizures. Recombinant adeno-associated virus containing miR-9-5p was constructed to overexpress miR-9-5p in vivo. The effects of miR-9-5p on the behavior and electroencephalographic activities of the lithium-pilocarpine rat model of epilepsy were tested. Bioinformatics analysis was used to predict the targets of miR-9-5p and explore its potential role in epilepsy and glioma-associated epilepsy.

Results

The expression of miR-9-5p increased at 6 h and 7 days after lithium-pilocarpine-induced seizures in rats. Overexpression of miR-9-5p significantly shortened the latency of seizures and increased seizure intensity at 10 min and 20 min after administration of pilocarpine (P < 0.05). Predicted targets of miR-9-5p were abundant and enriched in the brain, and affected various pathways related to epilepsy and tumor. Survival analysis revealed that overexpression of miR-9-5p significantly improved the survival of patients from with low-grade gliomas and glioblastomas. The involvement of miR-9-5p in the glioma-associated epileptic seizures and the improvement of glioma survival may be related to multiple pathways, including the Rho GTPases and hub genes included SH3PXD2B, ARF6, and ANK2.

Conclusions

miR-9-5p may play a key role in promoting epileptic seizures and improving glioma survival, probably through multiple pathways, including GTPases of the Rho family and hub genes including SH3PXD2B, ARF6 and ANK2. Understanding the roles of miR-9-5p in epilepsy and glioma and the underlying mechanisms may provide a theoretical basis for the diagnosis and treatment of patients with epilepsy and glioma.

Investigation of MicroRNA-134 as a Target against Seizures and SUDEP in a Mouse Model of Dravet Syndrome

Dravet syndrome (DS) is a catastrophic form of pediatric epilepsy mainly caused by noninherited mutations in the SCN1A gene. DS patients suffer severe and life-threatening focal and generalized seizures which are often refractory to available anti-seizure medication. Antisense oligonucleotides (ASOs) based approaches may offer treatment opportunities in DS. MicroRNAs are short noncoding RNAs that play a key role in brain structure and function by post-transcriptionally regulating gene expression, including ion channels. Inhibiting miRNA-134 (miR-134) using an antimiR ASO (Ant-134) has been shown to reduce evoked seizures in juvenile and adult mice and reduce epilepsy development in models of focal epilepsy. The present study investigated the levels of miR-134 and whether Ant-134 could protect against hyperthermia-induced seizures, spontaneous seizures and mortality (SUDEP) in F1.Scn1a(+/-)^tm1kea mice. At P17, animals were intracerebroventricular injected with 0.1-1 nmol of Ant-134 and subject to a hyperthermia challenge at postnatal day (P)18. A second cohort of P21 F1.Scn1a(+/-)^tm1kea mice received Ant-134 and were followed by video and EEG monitoring until P28 to track the incidence of spontaneous seizures and SUDEP. Hippocampal and cortical levels of miR-134 were similar between wild-type (WT) and F1.Scn1a(+/-)^tm1kea mice. Moreover, Ant-134 had no effect on hyperthermia-induced seizures, spontaneous seizures and SUDEP incidence were unchanged in Ant-134-treated DS mice. These findings suggest that targeting miR-134 does not have therapeutic applications in DS.

Induction of A Disintegrin and Metalloproteinase with Thrombospondin motifs 1 by a rare variant or cognitive activities reduces hippocampal amyloid-β and consequent Alzheimer’s disease risk

Amyloid-β (Aβ) derived from amyloid precursor protein (APP) hydrolysis is acknowledged as the predominant hallmark of Alzheimer’s disease (AD) that especially correlates to genetics and daily activities. In 2019, meta-analysis of AD has discovered five new risk loci among which A Disintegrin and Metalloproteinase with Thrombospondin motifs 1 (ADAMTS1) has been further suggested in 2021 and 2022. To verify the association, we re-sequenced ADAMTS1 of clinical AD samples and subsequently identified a novel rare variant c.–2067A > C with watchable relevance (whereas the P-value was not significant after adjustment). Dual-luciferase assay showed that the variant sharply stimulated ADAMTS1 expression. In addition, ADAMTS1 was also clearly induced by pentylenetetrazol-ignited neuronal activity and enriched environment (EE). Inspired by the above findings, we investigated ADAMTS1’s role in APP metabolism in vitro and in vivo. Results showed that ADAMTS1 participated in APP hydrolysis and consequently decreased Aβ generation through inhibiting β-secretase-mediated cleavage. In addition, we also verified that the hippocampal amyloid load of AD mouse model was alleviated by the introduction of ADAMTS1, and thus spatial cognition was restored as well. This study revealed the contribution of ADAMTS1 to the connection of genetic and acquired factors with APP metabolism, and its potential in reducing hippocampal amyloid and consequent risk of AD.

AntimiR targeting of microRNA-134 reduces seizures in a mouse model of Angelman syndrome

Angelman syndrome (AS) is a severe neurodevelopmental disorder featuring ataxia, cognitive impairment, and drug-resistant epilepsy. AS is caused by mutations or deletion of the maternal copy of the paternally imprinted UBE3A gene, with current precision therapy approaches focusing on re-expression of UBE3A. Certain phenotypes, however, are difficult to rescue beyond early development. Notably, a cluster of microRNA binding sites was reported in the untranslated Ube3a1 transcript, including for miR-134, suggesting that AS may be associated with microRNA dysregulation. Here, we report levels of miR-134 and key targets are normal in the hippocampus of mice carrying a maternal deletion of Ube3a (Ube3a ^m-/p+ ). Nevertheless, intracerebroventricular injection of an antimiR oligonucleotide inhibitor of miR-134 (Ant-134) reduced audiogenic seizure severity over multiple trials in 21- and 42-day-old AS mice. Interestingly, Ant-134 also improved distance traveled and center crossings of AS mice in the open-field test. Finally, we show that silencing miR-134 can upregulate targets of miR-134 in neurons differentiated from Angelman patient-derived induced pluripotent stem cells. These findings indicate that silencing miR-134 and possibly other microRNAs could be useful to treat clinically relevant phenotypes with a later developmental window in AS.

MicroRNA inhibition using antimiRs in acute human brain tissue sections

Antisense inhibition of microRNAs is an emerging preclinical approach to pharmacoresistant epilepsy. A leading candidate is an 'antimiR' targeting microRNA-134 (miR-134), but testing to date has used rodent models. Here, we develop an antimiR testing platform in human brain tissue sections. Brain specimens were obtained from patients undergoing resective surgery to treat pharmacoresistant epilepsy. Neocortical specimens were submerged in modified artificial cerebrospinal fluid (ACSF), dissected for clinical neuropathological examination, and unused material transferred for sectioning. Individual sections were incubated in oxygenated ACSF, containing either antimiR-134 or a non-targeting control antimiR, for 24 hours at room temperature. RNA integrity was assessed using BioAnalyzer processing, and individual miRNA levels measured using RT-qPCR. Specimens transported in ACSF could be used for neuropathological diagnosis and had good RNA integrity. AntimiR-134 mediated a dose-dependent knockdown of miR-134, with approximately 75% reduction of miR-134 at 1 µM and 90% reduction at 3 µM. These doses did not have off-target effects on expression of a selection of three other miRNAs. This is the first demonstration of antimiR-134 effects in live human brain tissues. The findings lend further support to the preclinical development of a therapy that targets miR-134 and offer a flexible platform for the pre-clinical testing of antimiRs, and other antisense oligonucleotide therapeutics, in human brain.

MicroRNA as an Early Biomarker of Neonatal Sepsis

Sepsis is a major cause of lethality in neonatal intensive care units. Despite significant advances in neonatal care and growing scientific knowledge about the disease, 4 of every 10 infants born in developed countries and suffering from sepsis die or experience considerable disability, including substantial and permanent neurodevelopmental impairment. Pharmacological treatment strategies for neonatal sepsis remain limited and mainly based upon early initiation of antibiotics and supportive treatment. In this context, numerous clinical and serum-based markers have been evaluated for diagnosing sepsis and evaluating its severity and etiology. MicroRNAs (miRNAs) do not encode for proteins but regulate gene expression by inhibiting the translation or transcription of their target mRNAs. Recently, it was demonstrated in adult patients that miRNAs are released into the circulation and that the spectrum of circulating miRNAs is altered during various pathologic conditions, such as inflammation, infection, and sepsis. Here, we summarize current findings on the role of circulating miRNAs in the diagnosis and staging of neonatal sepsis. The conclusions point to substantial diagnostic potential, and several miRNAs have been validated independently by different teams, namely miR-16a, miR-16, miR-96-5p, miR-141, miR-181a, and miR-1184.

PolyPurine Reverse Hoogsteen Hairpins Work as RNA Species for Gene Silencing

PolyPurine Reverse Hoogsteen Hairpins (PPRHs) are gene-silencing DNA-oligonucleotides developed in our laboratory that are formed by two antiparallel polypurine mirror repeat domains bound intramolecularly by Hoogsteen bonds. The aim of this work was to explore the feasibility of using viral vectors to deliver PPRHs as a gene therapy tool. After treatment with synthetic RNA, plasmid transfection, or viral infection targeting the survivin gene, viability was determined by the MTT assay, mRNA was determined by RT-qPCR, and protein levels were determined by Western blot. We showed that the RNA-PPRH induced a decrease in cell viability in a dose-dependent manner and an increase in apoptosis in PC-3 and HeLa cells. Both synthetic RNA-PPRH and RNA-PPRH intracellularly generated upon the transfection of a plasmid vector were able to reduce survivin mRNA and protein levels in PC-3 cells. An adenovirus type-5 vector encoding the PPRH against survivin was also able to decrease survivin mRNA and protein levels, leading to a reduction in HeLa cell viability. In this work, we demonstrated that PPRHs can also work as RNA species, either chemically synthesized, transcribed from a plasmid construct, or transcribed from viral vectors. Therefore, all these results are the proof of principle that viral vectors could be considered as a delivery system for PPRHs.

MicroRNAs in the development of resistance to antiseizure drugs and their potential as biomarkers in pharmacoresistant epilepsy

Although many new antiseizure drugs have been developed in the past decade, approximately 30%-40% of patients remain pharmacoresistant. There are no clinical tools or guidelines for predicting therapeutic response in individual patients, leaving them no choice other than to try all antiseizure drugs available as they suffer debilitating seizures with no relief. The discovery of predictive biomarkers and early identification of pharmacoresistant patients is of the highest priority in this group. MicroRNAs (miRNAs), a class of short noncoding RNAs negatively regulating gene expression, have emerged in recent years in epilepsy, following a broader trend of their exploitation as biomarkers of various complex human diseases. We performed a systematic search of the PubMed database for original research articles focused on miRNA expression level profiling in patients with drug-resistant epilepsy or drug-resistant precilinical models and cell cultures. In this review, we summarize 17 publications concerning miRNAs as potential new biomarkers of resistance to antiseizure drugs and their potential role in the development of drug resistance or epilepsy. Although numerous knowledge gaps need to be filled and reviewed, and articles share some study design pitfalls, several miRNAs dysregulated in brain tissue and blood serum were identified independently by more than one paper. These results suggest a unique opportunity for disease monitoring and personalized therapeutic management in the future.

Inhibition of miR-134-5p protects against kainic acid-induced excitotoxicity through Sirt3-mediated preservation of mitochondrial function

Epilepsy is a neurological disorder which is characterized by brain hyper-excitability and manifests as seizure. Due to its complicated pathogenesis, treatment for epilepsy still remains a huge challenge for neurology in the whole world. MciroRNA-134 (miR-134) is one kind of miRNAs which was firstly found abundant in synapses. In this study, we tried to unveil the role of inhibiting MciroRNA-134-5p (miR-134-5p) in excitotoxicity induced by kainic acid (KA) in the hippocampal neurons (HT22) cells. The results showed that treatment of KA increased the expression of miR-134-5p significantly and caused marked neuron excitotoxicity, evidenced by risen cell death rate, higher LDH release and aggravated cell viability. After suppressing miR-134-5p expression via transfecting HT22 cells with miR-134-5p antisense (Anti-134), cell viability was promoted obviously, along with decreased LDH release and cell death rate. In addition, KA-induced lipid peroxidation, cytochrome c release and mitochondrial ROS generation were also attenuated by Anti-134. The level of Sirtuin 3 (Sirt3) and its downstream antioxidant enzymes, such as mitochondrial superoxide dismutase 2 (SOD2), isocitrate dehydrogenase 2 (IDH2) and glutathione peroxidase (GSH-Px), were significantly higher in Anti-134 group compared with the control and scramble group. After inhibiting Sirt3 expression with SiRNA targeting Sirt3 (Si-Sirt3) and 3-(1H-1,2,3-triazol-4-yl) pyridine (3-TYP), the positive role of Anti-134 was apparently reversed. In conclusion, this research highly suggests that inhibition of miR-134-5p could protect neurons from KA-induced excitotoxicity through Sirt3-mediated preservation of mitochondrial function.

Opportunities and challenges for microRNA-targeting therapeutics for epilepsy

Epilepsy is a common and serious neurological disorder characterised by recurrent spontaneous seizures. Frontline pharmacotherapy includes small-molecule antiseizure drugs that typically target ion channels and neurotransmitter systems, but these fail in 30% of patients and do not prevent either the development or progression of epilepsy. An emerging therapeutic target is microRNA (miRNA), small noncoding RNAs that negatively regulate sets of proteins. Their multitargeting action offers unique advantages for certain forms of epilepsy with complex underlying pathophysiology, such as temporal lobe epilepsy (TLE). miRNA can be inhibited by designed antisense oligonucleotides (ASOs; e.g., antimiRs). Here, we outline the prospects for miRNA-based therapies. We review design considerations for nucleic acid-based approaches and the challenges and next steps in developing therapeutic miRNA-targeting molecules for epilepsy.

Systemic delivery of antagomirs during blood-brain barrier disruption is disease-modifying in experimental epilepsy

Oligonucleotide therapies offer precision treatments for a variety of neurological diseases, including epilepsy, but their deployment is hampered by the blood-brain barrier (BBB). Previous studies showed that intracerebroventricular injection of an antisense oligonucleotide (antagomir) targeting microRNA-134 (Ant-134) reduced evoked and spontaneous seizures in animal models of epilepsy. In this study, we used assays of serum protein and tracer extravasation to determine that BBB disruption occurring after status epilepticus in mice was sufficient to permit passage of systemically injected Ant-134 into the brain parenchyma. Intraperitoneal and intravenous injection of Ant-134 reached the hippocampus and blocked seizure-induced upregulation of miR-134. A single intraperitoneal injection of Ant-134 at 2 h after status epilepticus in mice resulted in potent suppression of spontaneous recurrent seizures, reaching a 99.5% reduction during recordings at 3 months. The duration of spontaneous seizures, when they occurred, was also reduced in Ant-134-treated mice. In vivo knockdown of LIM kinase-1 (Limk-1) increased seizure frequency in Ant-134-treated mice, implicating de-repression of Limk-1 in the antagomir mechanism. These studies indicate that systemic delivery of Ant-134 reaches the brain and produces long-lasting seizure-suppressive effects after systemic injection in mice when timed with BBB disruption and may be a clinically viable approach for this and other disease-modifying microRNA therapies.

miR-128 regulates epilepsy sensitivity in mice by suppressing SNAP-25 and SYT1 expression in the hippocampus

Epilepsy is accompanied by abnormal neurotransmission, and microRNAs, as versatile players in the modulation of gene expression, are important in epilepsy pathology. Here, we found that miR-128 expression was elevated in the acute seizure phase and decreased during the recurrent seizure phase after status epilepticus in mice. Both SNAP-25 and SYT1 are regulated by miR-128 in vitro and in vivo. Overexpressing miR-128 in cultured neurons decreased neurotransmitter released by suppressing SNAP-25 and SYT1 expression. Anti-miR-128 injection before kainic acid (KA) injection increased the sensitivity of mice to KA-induced seizures, while overexpressing miR-128 at the latent and recurrent phases had a neuroprotective effect in KA-induced seizures. Our study shows for the first time that miR-128, a key regulator of neurotransmission, plays an important role in epilepsy pathology and that miR-128 might be a potential candidate molecular target for epilepsy therapy.

An Insight into Molecular Mechanisms and Novel Therapeutic Approaches in Epileptogenesis

Epilepsy is the second most common neurological disease with abnormal neural activity involving the activation of various intracellular signalling transduction mechanisms. The molecular and system biology mechanisms responsible for epileptogenesis are not well defined or understood. Neuroinflammation, neurodegeneration and Epigenetic modification elicit epileptogenesis. The excessive neuronal activities in the brain are associated with neurochemical changes underlying the deleterious consequences of excitotoxicity. The prolonged repetitive excessive neuronal activities extended to brain tissue injury by the activation of microglia regulating abnormal neuroglia remodelling and monocyte infiltration in response to brain lesions inducing axonal sprouting contributing to neurodegeneration. The alteration of various downstream transduction pathways resulted in intracellular stress responses associating endoplasmic reticulum, mitochondrial and lysosomal dysfunction, activation of nucleases, proteases mediated neuronal death. The recently novel pharmacological agents modulate various receptors like mTOR, COX-2, TRK, JAK-STAT, epigenetic modulators and neurosteroids are used for attenuation of epileptogenesis. Whereas the various molecular changes like the mutation of the cell surface, nuclear receptor and ion channels focusing on repetitive episodic seizures have been explored by preclinical and clinical studies. Despite effective pharmacotherapy for epilepsy, the inadequate understanding of precise mechanisms, drug resistance and therapeutic failure are the current fundamental problems in epilepsy. Therefore, the novel pharmacological approaches evaluated for efficacy on experimental models of epilepsy need to be identified and validated. In addition, we need to understand the downstream signalling pathways of new targets for the treatment of epilepsy. This review emphasizes on the current state of novel molecular targets as therapeutic approaches and future directions for the management of epileptogenesis. Novel pharmacological approaches and clinical exploration are essential to make new frontiers in curing epilepsy.

Antagomir-mediated suppression of microRNA-134 reduces kainic acid-induced seizures in immature mice

MicroRNAs are short non-coding RNAs that negatively regulate protein levels and perform important roles in establishing and maintaining neuronal network function. Previous studies in adult rodents have detected upregulation of microRNA-134 after prolonged seizures (status epilepticus) and demonstrated that silencing microRNA-134 using antisense oligonucleotides, termed antagomirs, has potent and long-lasting seizure-suppressive effects. Here we investigated whether targeting microRNA-134 can reduce or delay acute seizures in the immature brain. Status epilepticus was induced in 21 day-old (P21) male mice by systemic injection of 5 mg/kg kainic acid. This triggered prolonged electrographic seizures and select bilateral neuronal death within the CA3 subfield of the hippocampus. Expression of microRNA-134 and functional loading to Argonaute-2 was not significantly changed in the hippocampus after seizures in the model. Nevertheless, when levels of microRNA-134 were reduced by prior intracerebroventricular injection of an antagomir, kainic acid-induced seizures were delayed and less severe and mice displayed reduced neuronal death in the hippocampus. These studies demonstrate targeting microRNA-134 may have therapeutic applications for the treatment of seizures in children.

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.

Nucleic acids therapeutics using PolyPurine Reverse Hoogsteen hairpins

PolyPurine Reverse Hoogsteen hairpins (PPRHs) are DNA hairpins formed by intramolecular reverse Hoogsteen bonds which can bind to polypyrimidine stretches in dsDNA by Watson:Crick bonds, thus forming a triplex and displacing the fourth strand of the DNA complex. PPRHs were first described as a gene silencing tool in vitro for DHFR, telomerase and survivin genes. Then, the effect of PPRHs directed against the survivin gene was also determined in vivo using a xenograft model of prostate cancer cells (PC3). Since then, the ability of PPRHs to inhibit gene expression has been explored in other genes involved in cancer (BCL-2, mTOR, topoisomerase, C-MYC and MDM2), in immunotherapy (SIRPα/CD47 and PD-1/PD-L1 tandem) or in replication stress (WEE1 and CHK1). Furthermore, PPRHs have the ability to target the complementary strand of a G-quadruplex motif as a regulatory element of the TYMS gene. PPRHs have also the potential to correct point mutations in the DNA as shown in two collections of CHO cell lines bearing mutations in either the dhfr or aprt loci. Finally, based on the capability of PPRHs to form triplexes, they have been incorporated as probes in biosensors for the determination of the DNA methylation status of PAX-5 in cancer and the detection of mtLSU rRNA for the diagnosis of Pneumocystis jirovecii. Of note, PPRHs have high stability and do not present immunogenicity, hepatotoxicity or nephrotoxicity in vitro. Overall, PPRHs constitute a new economical biotechnological tool with multiple biomedical applications.

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.

Genome-wide microRNA profiling of plasma from three different animal models identifies biomarkers of temporal lobe epilepsy

Epilepsy diagnosis is complex, requires a team of specialists and relies on in-depth patient and family history, MRI-imaging and EEG monitoring. There is therefore an unmet clinical need for a non-invasive, molecular-based, biomarker to either predict the development of epilepsy or diagnose a patient with epilepsy who may not have had a witnessed seizure. Recent studies have demonstrated a role for microRNAs in the pathogenesis of epilepsy. MicroRNAs are short non-coding RNA molecules which negatively regulate gene expression, exerting profound influence on target pathways and cellular processes. The presence of microRNAs in biofluids, ease of detection, resistance to degradation and functional role in epilepsy render them excellent candidate biomarkers. Here we performed the first multi-model, genome-wide profiling of plasma microRNAs during epileptogenesis and in chronic temporal lobe epilepsy animals. From video-EEG monitored rats and mice we serially sampled blood samples and identified a set of dysregulated microRNAs comprising increased miR-93-5p, miR-142-5p, miR-182-5p, miR-199a-3p and decreased miR-574-3p during one or both phases. Validation studies found miR-93-5p, miR-199a-3p and miR-574-3p were also dysregulated in plasma from patients with intractable temporal lobe epilepsy. Treatment of mice with common anti-epileptic drugs did not alter the expression levels of any of the five miRNAs identified, however administration of an anti-epileptogenic microRNA treatment prevented dysregulation of several of these miRNAs. The miRNAs were detected within the Argonuate2-RISC complex from both neurons and microglia indicating these miRNA biomarker candidates can likely be traced back to specific brain cell types. The current studies identify additional circulating microRNA biomarkers of experimental and human epilepsy which may support diagnosis of temporal lobe epilepsy via a quick, cost-effective rapid molecular-based test.

A systems approach delivers a functional microRNA catalog and expanded targets for seizure suppression in temporal lobe epilepsy

Temporal lobe epilepsy is the most common drug-resistant form of epilepsy in adults. The reorganization of neural networks and the gene expression landscape underlying pathophysiologic network behavior in brain structures such as the hippocampus has been suggested to be controlled, in part, by microRNAs. To systematically assess their significance, we sequenced Argonaute-loaded microRNAs to define functionally engaged microRNAs in the hippocampus of three different animal models in two species and at six time points between the initial precipitating insult through to the establishment of chronic epilepsy. We then selected commonly up-regulated microRNAs for a functional in vivo therapeutic screen using oligonucleotide inhibitors. Argonaute sequencing generated 1.44 billion small RNA reads of which up to 82% were microRNAs, with over 400 unique microRNAs detected per model. Approximately half of the detected microRNAs were dysregulated in each epilepsy model. We prioritized commonly up-regulated microRNAs that were fully conserved in humans and designed custom antisense oligonucleotides for these candidate targets. Antiseizure phenotypes were observed upon knockdown of miR-10a-5p, miR-21a-5p, and miR-142a-5p and electrophysiological analyses indicated broad safety of this approach. Combined inhibition of these three microRNAs reduced spontaneous seizures in epileptic mice. Proteomic data, RNA sequencing, and pathway analysis on predicted and validated targets of these microRNAs implicated derepressed TGF-β signaling as a shared seizure-modifying mechanism. Correspondingly, inhibition of TGF-β signaling occluded the antiseizure effects of the antagomirs. Together, these results identify shared, dysregulated, and functionally active microRNAs during the pathogenesis of epilepsy which represent therapeutic antiseizure targets.

Antagomirs targeting miR-142-5p attenuate pilocarpine-induced status epilepticus in mice

MicroRNAs (miRNAs) are reported to involve in pathogenesis of temporal lobe epilepsy (TLE). miR-142-5p is found increased in TLE, but its role remains unknown. In the study, we established a mouse model of status epilepticus (SE) with pilocarpine and a cell model of TLE. Quantitative real-time PCR revealed an up-regulation of miR-142-5p and down-regulation of mitochondrial Rho 1 (Miro1) in the mouse mode of SE. Administration of miR-142-5p antagomirs via intracerebroventricular injection attenuated pilocarpine-induced SE and hippocampal damage, and alleviated mitochondrial dysfunction along with increased mitochondrial membrane potential and intracellular ATP and Ca (2+) levels. The expression of mitochondrial trafficking kinesin protein (Trak) 1 and Trak2 was up-regulated by inhibiting miR-142-5p. Antagomirs targeting miR-142-5p suppressed pilocarpine-induced oxidative stress as evidenced by decreased ROS generation and MPO activity, and increased SOD activity. Silencing miR-142-5p reduced neuronal death in pilocarpine-treated hippocampus and magnesium-free (MGF)-treated neurons. Inhibition of miR-142-5p decreased cytoplasmic Cytochrome C and increased mitochondrial Cytochrome C, reduced cleaved-caspase3 and Bax levels, and elevated Bcl2 in vivo and in vitro. Further, dual-luciferase assay verified Miro1 as a target of miR-142-5p, suggesting that miR-142-5p might function via targeting Mrio1. Depletion of Miro1 inhibited the protective effect of silencing miR-142-5p on hippocampal neurons in vitro. Taken together, down-regulation of miR-142-5p via targeting Miro1 inhibits neuronal death and mitochondrial dysfunction, and thus attenuates pilocarpine-induced SE, suggesting the potential involvement of miR-142-5p in the pathogenesis of TLE.

The Promise and Challenges of Developing miRNA-Based Therapeutics for Parkinson's Disease

MicroRNAs (miRNAs) are small double-stranded RNAs that exert a fine-tuning sequence-specific regulation of cell transcriptome. While one unique miRNA regulates hundreds of mRNAs, each mRNA molecule is commonly regulated by various miRNAs that bind to complementary sequences at 3’-untranslated regions for triggering the mechanism of RNA interference. Unfortunately, dysregulated miRNAs play critical roles in many disorders, including Parkinson’s disease (PD), the second most prevalent neurodegenerative disease in the world. Treatment of this slowly, progressive, and yet incurable pathology challenges neurologists. In addition to L-DOPA that restores dopaminergic transmission and ameliorate motor signs (i.e., bradykinesia, rigidity, tremors), patients commonly receive medication for mood disorders and autonomic dysfunctions. However, the effectiveness of L-DOPA declines over time, and the L-DOPA-induced dyskinesias commonly appear and become highly disabling. The discovery of more effective therapies capable of slowing disease progression –a neuroprotective agent–remains a critical need in PD. The present review focus on miRNAs as promising drug targets for PD, examining their role in underlying mechanisms of the disease, the strategies for controlling aberrant expressions, and, finally, the current technologies for translating these small molecules from bench to clinics.

Epigenetic mechanisms of neurodegenerative diseases and acute brain injury

Epigenetic modifications are emerging as major players in the pathogenesis of neurodegenerative disorders and susceptibility to acute brain injury. DNA and histone modifications act together with non-coding RNAs to form a complex gene expression machinery that adapts the brain to environmental stressors and injury response. These modifications influence cell-level operations like neurogenesis and DNA repair to large, intricate processes such as brain patterning, memory formation, motor function and cognition. Thus, epigenetic imbalance has been shown to influence the progression of many neurological disorders independent of aberrations in the genetic code. This review aims to highlight ways in which epigenetics applies to several commonly researched neurodegenerative diseases and forms of acute brain injury as well as shed light on the benefits of epigenetics-based treatments.

Perspective: Therapeutic Potential of Flavonoids as Alternative Medicines in Epilepsy

Epilepsy is a chronic neurological disorder that affects many people worldwide. Temporal lobe epilepsy is the most common and most studied type of epilepsy, but the pathological mechanisms underlying this condition are poorly understood. More than 20 antiepileptic drugs (AEDs) have been developed and used for the treatment of epilepsy; however, 30% of patients still experience uncontrolled epilepsy and associated comorbidities, which impair their quality of life. In addition, various side effects have been reported for AEDs, such as drowsiness, unsteadiness, dizziness, blurred or double vision, tremor (shakiness), greater risk of infections, bruising, and bleeding. Thus, critical medical needs remain unmet for patients with uncontrolled epilepsy. Flavonoids belong to a subclass of polyphenols that are widely present in fruits, vegetables, and certain beverages. Recently, many studies have reported that some flavonoids elicit various beneficial effects in patients with epilepsy without causing the side effects associated with conventional medical therapies. Moreover, flavonoids may have a property of regulating microRNA expression associated with inflammation and cell survival. These findings suggest that flavonoids, which are more effective but impose fewer adverse effects than conventional AEDs, could be used in the treatment of epilepsy.

Opportunities and challenges in psychopharmacology

This review addresses novel approaches for influencing the transcriptome, the epigenome, the microbiome, the proteome, and the energy metabolome. These innovations help develop psychotropic medications which will directly reach the molecular targets, leading to beneficial effects, and which will be individually adapted to provide more efficacy and less toxicity. The series of advances described here show that these once utopian goals for psychiatric treatment are now real themes of research, indicating that the future path for psychopharmacology might not be as narrow and grim as considered during the last few decades.


Targeting microRNA-134 for seizure control and disease modification in epilepsy

MicroRNA-134 is a brain-enriched small noncoding RNA that has been implicated in diverse neuronal functions, including regulating network excitability. Increased expression of microRNA-134 has been reported in several experimental epilepsy models and in resected brain tissue from temporal lobe epilepsy patients. Rodent studies have demonstrated that reducing microRNA-134 expression in the brain using antisense oligonucleotides can increase seizure thresholds and attenuate status epilepticus. Critically, inhibition of microRNA-134 after status epilepticus can potently reduce the occurrence of spontaneous recurrent seizures. Altered plasma levels of microRNA-134 have been reported in epilepsy patients, suggesting microRNA-134 may have diagnostic value as a biomarker. This review summarises findings on the cellular functions of microRNA-134, as well as the preclinical evidence supporting anti-seizure and disease-modifying effects of targeting microRNA-134 in epilepsy. Finally, we draw attention to unanswered questions and some of the challenges and opportunities involved in preclinical development of a microRNA-based oligonucleotide treatment for epilepsy.

MicroRNAs change the games in central nervous system pharmacology

MicroRNAs (miRNAs) represent a class of important post-transcriptional regulators of gene expression, enabling cells to follow their intrinsic developmental program. By directly binding to their targets, miRNAs can both promote transcriptional patterns in crucial steps of cell growth, and act as powerful buffering system that titrate protein content in case of aberrant gene expression. The literature of the last decade showed that the presence of tissue-enriched miRNAs in body fluids could be reminiscent of disease state. This is particularly relevant in neurodegenerative disorders, in which peripheral biomarkers could be helpful means to detect disease onset. However, dysregulation of miRNAs is not merely a consequence of disease, but directly contributes to pathological outcomes. On this basis, increasing interest is growing in the development of pharmacological agents targeting specific miRNAs. Actually, this apparently futuristic approach is already part of the current therapies. In fact, several drugs approved for CNS disorders, such as L-Dopa or valproic acid, were also demonstrated to restore some miRNAs. Moreover, ongoing clinical trials demonstrated that miRNA-based drugs are effective against tumors, suggesting that miRNAs also represent a promising class of therapeutic molecules. However, several issues still need to be addressed, particularly in case of CNS diseases, in which stability and delivery are crucial aspects of the therapy. In this commentary, we highlighted potential advantages and limitations of miRNAs as next generation targets in CNS pharmacology, focusing on multiple sclerosis, a chronic demyelinating disease lacking specific therapeutic targets and bona-fide biomarkers.

Antagonizing Increased miR-135a Levels at the Chronic Stage of Experimental TLE Reduces Spontaneous Recurrent Seizures

Mesial temporal lobe epilepsy (mTLE) is a chronic neurological disease characterized by recurrent seizures. The antiepileptic drugs currently available to treat mTLE are ineffective in one-third of patients and lack disease-modifying effects. miRNAs, a class of small noncoding RNAs which control gene expression at the post-transcriptional level, play a key role in the pathogenesis of mTLE and other epilepsies. Although manipulation of miRNAs at acute stages has been reported to reduce subsequent spontaneous seizures, it is uncertain whether targeting miRNAs at chronic stages of mTLE can also reduce seizures. Furthermore, the functional role and downstream targets of most epilepsy-associated miRNAs remain poorly understood. Here, we show that miR-135a is selectively upregulated within neurons in epileptic brain and report that targeting miR-135a in vivo using antagomirs after onset of spontaneous recurrent seizures can reduce seizure activity at the chronic stage of experimental mTLE in male mice. Further, by using an unbiased approach combining immunoprecipitation and RNA sequencing, we identify several novel neuronal targets of miR-135a, including Mef2a Mef2 proteins are key regulators of excitatory synapse density. Mef2a and miR-135a show reciprocal expression regulation in human (of both sexes) and experimental TLE, and miR-135a regulates dendritic spine number and type through Mef2. Together, our data show that miR-135a is target for reducing seizure activity in chronic epilepsy, and that deregulation of miR-135a in epilepsy may alter Mef2a expression and thereby affect synaptic function and plasticity.SIGNIFICANCE STATEMENT miRNAs are post-transcriptional regulators of gene expression with roles in the pathogenesis of epilepsy. However, the precise mechanism of action and therapeutic potential of most epilepsy-associated miRNAs remain poorly understood. Our study reveals dramatic upregulation of the key neuronal miRNA miR-135a in both experimental and human mesial temporal lobe epilepsy. Silencing miR-135a in experimental temporal lobe epilepsy reduces seizure activity at the spontaneous recurrent seizure stage. These data support the exciting possibility that miRNAs can be targeted to combat seizures after spontaneous seizure activity has been established. Further, by using unbiased approaches novel neuronal targets of miR-135a, including members of the Mef2 protein family, are identified that begin to explain how deregulation of miR-135a may contribute to epilepsy.

Co-administration of Anti microRNA-124 and -137 Oligonucleotides Prevents Hippocampal Neural Stem Cell Loss Upon Non-convulsive Seizures

Convulsive seizures promote adult hippocampal neurogenesis (AHN) through a transient activation of neural stem/progenitor cells (NSPCs) in the subgranular zone (SGZ) of the dentate gyrus (DG). However, in a significant population of epilepsy patients, non-convulsive seizures (ncSZ) are observed. The response of NSPCs to non-convulsive seizure induction has not been characterized before. We here studied first the short-term effects of controlled seizure induction on NSPCs fate and identity. We induced seizures of controlled intensity by intrahippocampally injecting increasing doses of the chemoconvulsant kainic acid (KA) and analyzed their effect on subdural EEG recordings, hippocampal structure, NSPC proliferation and the number and location of immature neurons shortly after seizure onset. After establishing a KA dose that elicits ncSZ, we then analyzed the effects of ncSZ on NSPC proliferation and NSC identity in the hippocampus. ncSZ specifically triggered neuroblast proliferation, but did not induce proliferation of NSPCs in the SGZ, 3 days post seizure onset. However, ncSZ induced significant changes in NSPC composition in the hippocampus, including the generation of reactive NSCs. Interestingly, intrahippocampal injection of a combination of two anti microRNA oligonucleotides targeting microRNA-124 and -137 normalized neuroblast proliferation and prevented NSC loss in the DG upon ncSZ. Our results show for the first time that ncSZ induce significant changes in neuroblast proliferation and NSC composition. Simultaneous antagonism of both microRNA-124 and -137 rescued seizure-induced alterations in NSPC, supporting their coordinated action in the regulation of NSC fate and proliferation and their potential for future seizure therapies.

Non-coding RNAs: the gatekeepers of neural network activity

Non-coding RNAs have emerged as potent regulators of numerous cellular processes. In neurons and circuits, these molecules serve especially critical functions that ensure neural activity is maintained within appropriate physiological parameters. Their targets include synaptic proteins, ion channels, neurotransmitter receptors, and components of essential signaling cascades. Here, we discuss how several species of non-coding RNAs (ncRNAs) regulate intrinsic excitability and synaptic transmission, both during development and in mature circuits. Furthermore, we present the relationships between aberrant ncRNA expression and psychiatric disorders. The research presented here demonstrates how ncRNAs can be useful tools for elucidating fundamental neurobiology mechanisms and identifying the key molecular players.

Inhibition of miR-155 Limits Neuroinflammation and Improves Functional Recovery After Experimental Traumatic Brain Injury in Mice

Micro-RNAs (miRs) are short, noncoding RNAs that negatively regulate gene expression at the post-transcriptional level and have been implicated in the pathophysiology of secondary damage after traumatic brain injury (TBI). Among miRs linked to inflammation, miR-155 has been implicated as a pro-inflammatory factor in a variety of organ systems. We examined the expression profile of miR-155, following experimental TBI (controlled cortical impact) in adult male C57Bl/6 mice, as well as the effects of acute or delayed administration of a miR-155 antagomir on post-traumatic neuroinflammatory responses and neurological recovery. Trauma robustly increased miR-155 expression in the injured cortex over 7 days. Similar TBI-induced miR-155 expression changes were also found in microglia/macrophages isolated from the injured cortex at 7 days post-injury. A miR-155 hairpin inhibitor (antagomir; 0.5 nmol), administered intracerebroventricularly (ICV) immediately after injury, attenuated neuroinflammatory markers at both 1 day and 7 days post-injury and reduced impairments in spatial working memory. Delayed ICV infusion of the miR-155 antagomir (0.5 nmol/day), beginning 24 h post-injury and continuing for 6 days, attenuated neuroinflammatory markers at 7 days post-injury and improved motor, but not cognitive, function through 28 days. The latter treatment limited NADPH oxidase 2 expression changes in microglia/macrophages in the injured cortex and reduced cortical lesion volume. In summary, TBI causes a robust and persistent neuroinflammatory response that is associated with increased miR-155 expression in microglia/macrophages, and miR-155 inhibition reduces post-traumatic neuroinflammatory responses and improves neurological recovery. Thus, miR-155 may be a therapeutic target for TBI-related neuroinflammation.

d- andl-Aspartate regulates growth performance, inflammation and intestinal microbial community in young pigs

Dietary 1%d-Asp andl-Asp affect the growth performance and inflammation in young pigs, which might be associated with gut microbiota.

Opportunities and challenges in psychopharmacology

This review addresses novel approaches for influencing the transcriptome, the epigenome, the microbiome, the proteome, and the energy metabolome. These innovations help develop psychotropic medications which will directly reach the molecular targets, leading to beneficial effects, and which will be individually adapted to provide more efficacy and less toxicity. The series of advances described here show that these once utopian goals for psychiatric treatment are now real themes of research, indicating that the future path for psychopharmacology might not be as narrow and grim as considered during the last few decades.
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Profiling of Argonaute-2-loaded microRNAs in a mouse model of frontotemporal dementia with parkinsonism-17

Tauopathies are a group of neurodegenerative diseases characterized by the pathological aggregation of the microtubule-associated protein tau. These include more than 20 diseases, with Alzheimer's disease being the most frequent. While pathological and neurotoxic effects of tau are well documented, the mechanisms by which tau can promote neurodegeneration are less clear. Increasing evidence suggests a functional role for microRNAs in the pathogenesis of tauopathies, with altered expression and function of microRNAs in experimental models and patient brain. To determine whether a pathological expression of tau leads to altered microRNA expression, we investigated a mouse model (VLW), which overexpresses tau carrying three mutations identified in patients suffering from frontotemporal dementia with parkinsonism-17. Argonaute-2-bound microRNAs were co-immunoprecipitated using hippocampal tissue to identify active microRNAs within the model and quantified using a genome-wide high-throughput qPCR-based microRNA platform. While similar numbers of microRNAs are present between wild-type and VLW mice, a prominent increase in Argonaute-2-bound levels of microRNAs could be observed in VLW mice. This included microRNA-134, microRNA-99a and microRNA-101. Subsequent experiments revealed this increase in Argonaute-2 loading of microRNAs to correlate with increased microRNA expression. Our in vivo study suggests that a pathological tau overexpression may lead to an increase in active microRNAs, possibly contributing to dysregulation of gene expression and tau-induced pathology.

Discovery and validation of blood microRNAs as molecular biomarkers of epilepsy: Ways to close current knowledge gaps

There is a major unmet need for biomarkers of epilepsy. Biofluids such as blood offer a potential source of molecular biomarkers. MicroRNAs (miRNAs) fulfill several key requirements for a blood‐based molecular biomarker being enriched in the brain and dysregulated in epileptic brain tissue, and manipulation of miRNAs can have seizure‐suppressive and disease‐modifying effects in preclinical models. Biofluid miRNAs also possess qualities that are favorable for translation, including stability and easy and cheap assay techniques. Herein we review findings from both clinical and animal models. Studies have featured a mix of unbiased profiling and hypothesis‐driven efforts. Blood levels of several brain‐enriched miRNAs are altered in patients with epilepsy and in patients with drug‐resistant compared to drug‐responsive seizures, with encouraging receiver‐operating characteristic (ROC) curve analyses, both in terms of sensitivity and specificity. Both focal and generalized epilepsies are associated with altered blood miRNA profiles, and associations with clinical parameters including seizure burden have been reported. Results remain preliminary, however. There is a need for continued discovery and validation efforts that include multicenter studies and attention to study design, sample collection methodology, and quality control. Studies focused on epileptogenesis as well as associations with covariables such as sex, etiology, and timing of sampling remain limited. We identify 10 knowledge gaps and propose experiments to close these. If adequately addressed, biofluid miRNAs may be an important future source of diagnostic biomarkers that could also support forthcoming trials of antiepileptogenesis or disease‐modifying therapies.

Epigenetic changes in status epilepticus

Epigenetics refers broadly to processes that influence medium- to long-term expression of genes through changes to the readability and accessibility of the genome to transcription. The mediators include DNA methylation, posttranslational modification of histone proteins, and noncoding RNAs. The present review focuses on recent findings showing epigenetic processes influence susceptibility to and severity of status epilepticus, while status epilepticus in turn drives changes to epigenetic marks that affect the gene expression landscape underlying epileptogenesis. Experimental status epilepticus triggers select, spatiotemporal hypo- and hypermethylation changes throughout the genome. Experimental manipulations that alter DNA methylation after status epilepticus are associated with amelioration of cognitive and hyperexcitability phenotypes. Prolonged seizures also modify chromatin compaction via acetylation and other changes to histones and their expression. Finally, short noncoding RNAs called microRNAs target networks of genes through posttranscriptional and other mechanisms and their modulation can alter status epilepticus as well as serve as potential molecular biomarkers. Long noncoding RNAs have also been targeted to influence expression of genes affecting electrophysiological functions of neurons. In summary, epigenetic processes can modulate status epilepticus, and status epilepticus imposes changes on the epigenome, which together provide novel insight into pathomechanisms, therapy, and biomarkers for status epilepticus.

Delivery of miRNA-Targeted Oligonucleotides in the Rat Striatum by Magnetofection with Neuromag®

MicroRNAs (miRNAs) regulate gene expression at posttranscriptional level by triggering RNA interference. In such a sense, aberrant expressions of miRNAs play critical roles in the pathogenesis of many disorders, including Parkinson’s disease (PD). Controlling the level of specific miRNAs in the brain is thus a promising therapeutic strategy for neuroprotection. A fundamental need for miRNA regulation (either replacing or inhibition) is a carrier capable of delivering oligonucleotides into brain cells. This study aimed to examine a polymeric magnetic particle, Neuromag^®, for delivery of synthetic miRNA inhibitors in the rat central nervous system. We injected the miRNA inhibitor complexed with Neuromag^® into the lateral ventricles next to the striatum, by stereotaxic surgery. Neuromag efficiently delivered oligonucleotides in the striatum and septum areas, as shown by microscopy imaging of fluorescein isothiocyanate (FITC)-labeled oligos in astrocytes and neurons. Transfected oligos showed efficacy concerning miRNA inhibition. Neuromag^®-structured miR-134 antimiR (0.36 nmol) caused a significant 0.35 fold decrease of striatal miR-134, as revealed by real-time quantitative polymerase chain reaction (RT-qPCR). In conclusion, the polymeric magnetic particle Neuromag^® efficiently delivered functional miRNA inhibitors in brain regions surrounding lateral ventricles, particularly the striatum. This delivery system holds potential as a promising miRNA-based disease-modifying drug and merits further pre-clinical studies using animal models of PD.

Spared CA1 pyramidal neuron function and hippocampal performance following antisense knockdown of microRNA-134

Objective

Inhibition of microRNA‐134 by an oligonucleotide antagomir (ant‐134) has been shown to produce powerful antiseizure effects in multiple models of epilepsy. However, to successfully translate the treatment to the clinic, it is important to assess what potential adverse effects it may have on naive brain tissue.

Methods

To investigate this, adult male Sprague‐Dawley rats were treated with either ant‐134 or a scrambled control sequence. Animals were later assessed for spatial navigation, before ex vivo slices were taken to assess the effects of microRNA‐134 knockdown on well‐defined measures of intrinsic and synaptic properties.

Results

Hippocampal field potential recordings determined that silencing of microRNA‐134 by ant‐134 injection was associated with a reduction in epileptiform activity following application of 9 mmol/L K⁺. Nevertheless, rats performed normally in the novel object location test. Action potential waveforms and miniature excitatory synaptic currents recorded in CA1 pyramidal neurons were unaffected by ant‐134.

Significance

These results demonstrate that ant‐134 confers a seizure‐protective effect without obvious interference with hippocampal neuronal properties or network function. These findings support further development of this novel approach to epilepsy treatment.

Epilepsy

Epilepsy affects all age groups and is one of the most common and most disabling neurological disorders. The accurate diagnosis of seizures is essential as some patients will be misdiagnosed with epilepsy, whereas others will receive an incorrect diagnosis. Indeed, errors in diagnosis are common, and many patients fail to receive the correct treatment, which often has severe consequences. Although many patients have seizure control using a single medication, others require multiple medications, resective surgery, neuromodulation devices or dietary therapies. In addition, one-third of patients will continue to have uncontrolled seizures. Epilepsy can substantially impair quality of life owing to seizures, comorbid mood and psychiatric disorders, cognitive deficits and adverse effects of medications. In addition, seizures can be fatal owing to direct effects on autonomic and arousal functions or owing to indirect effects such as drowning and other accidents. Deciphering the pathophysiology of epilepsy has advanced the understanding of the cellular and molecular events initiated by pathogenetic insults that transform normal circuits into epileptic circuits (epileptogenesis) and the mechanisms that generate seizures (ictogenesis). The discovery of >500 genes associated with epilepsy has led to new animal models, more precise diagnoses and, in some cases, targeted therapies.

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.