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

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.

HSV-1 latency-associated transcript miR-H3 and miR-H4 target STXBP1 and GABBR2 genes

During latent infection, the HSV-1 virus generates only a single transcript, LAT, which encodes six miRNAs. The GABAergic pathway signaling system is an essential cell signaling pathway influenced by various therapeutic targets and some brain disorders, such as epilepsy. This study found that miRNAs encoding LAT might target the STXBP1 and GABBR2 genes, which are among the significant genes in the GABAergic pathway. Bioinformatic analysis utilizing TargetScan version 5.2 and the RNA22 tools uncovered miRNAs encoding LAT that can influence STXBP1 and GABBR2 transcripts. To evaluate the targeting effect of candidate microRNAs encoding LAT, namely, miR-H3 and miR-H4, LAT constructs were transfected into HEK 293T cells. The expression levels of microRNAs encoding LAT, as well as STXBP1 and GABBR2, were assayed by real-time PCR. Finally, the targeting potential of STXBP1 and GABBR2 3'UTR by LAT-encoded microRNAs was evaluated by the luciferase assay. In the current study, the bioinformatic tool TargetScan demonstrated that miR-H3 has the potential to target the transcripts of the STXBP1 and GABBR2 genes, whereas miR-H4 solely targeted GABBR2. On the other hand, the bioinformatic tool RNA22 validated the potential targeting of STXBP1 and GABBR2 by miR-H3 and miR-H4. Our findings showed that overexpression of miR-H4, miR-H3, or LAT significantly decreased STXBP1 gene expression by an average of 0.0593-fold, 0.237-fold, and 0.84-fold, respectively. Similarly, overexpression of miR-H3 or miR-H4 decreased GABBR2 expression by an average of 0.055- or 0.687-fold, respectively. Notably, targeting the GABBR2 3'UTR with the LAT transcript had no detectable effect. The evaluation of the targeting potential of STXBP1 and GABBR2 3'UTR by microRNAs encoded by LAT was conducted with a luciferase assay. Our results showed that miR-H3 overexpression reduces Renilla expression in psiCHECK2 plasmids with STXBP1 or GABBR2 3'UTR genes by 0.62- and 0.55-fold, respectively. miR-H4 reduced Renilla gene expression regulated by GABBR2's 3'UTR plasmid but had no effect on the Renilla gene expression regulated by STXBP1's 3'UTR. When the LAT transcript was overexpressed, there was a decrease in Renilla expression by 0.44-fold because of the regulation of STXBP1's 3'UTR. However, there was no significant effect observed through the control of GABBR2's 3'UTR.

Molecular EPISTOP, a comprehensive multi-omic analysis of blood from Tuberous Sclerosis Complex infants age birth to two years

We present a comprehensive multi-omic analysis of the EPISTOP prospective clinical trial of early intervention with vigabatrin for pre-symptomatic epilepsy treatment in Tuberous Sclerosis Complex (TSC), in which 93 infants with TSC were followed from birth to age 2 years, seeking biomarkers of epilepsy development. Vigabatrin had profound effects on many metabolites, increasing serum deoxycytidine monophosphate (dCMP) levels 52-fold. Most serum proteins and metabolites, and blood RNA species showed significant change with age. Thirty-nine proteins, metabolites, and genes showed significant differences between age-matched control and TSC infants. Six also showed a progressive difference in expression between control, TSC without epilepsy, and TSC with epilepsy groups. A multivariate approach using enrollment samples identified multiple 3-variable predictors of epilepsy, with the best having a positive predictive value of 0.987. This rich dataset will enable further discovery and analysis of developmental effects, and associations with seizure development in TSC.

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.

The complexities underlying epilepsy in people with glioblastoma

Seizures are among the most common clinical signs in people with glioblastoma. Advances over the past 5 years, including new clinical trial data, have increased the understanding of why some individuals with glioblastoma are susceptible to seizures, how seizures manifest clinically, and what implications seizures have for patient management. The pathophysiology of epilepsy in people with glioblastoma relates to a combination of intrinsic epileptogenicity of tumour tissue, alterations in the tumour and peritumoural microenvironment, and the physical and functional disturbance of adjacent brain structures. Successful management of epilepsy in people with glioblastoma remains challenging; factors such as drug-drug interactions between cancer therapies and antiseizure medications, and medication side-effects, can affect seizure outcomes and quality of life. Advances in novel therapies provide some promise for people with glioblastoma; however, the effects of these therapies on seizures are yet to be fully determined. Looking forward, insights into electrical activity as a driver of tumour cell growth and the intrinsic hyperexcitability of tumour tissue might represent useful targets for treatment and disease modification. There is a pressing need for large randomised clinical trials in this field.

Proteomic and Bioinformatic Tools to Identify Potential Hub Proteins in the Audiogenic Seizure-Prone Hamster GASH/Sal

The GASH/Sal (Genetic Audiogenic Seizure Hamster, Salamanca) is a model of audiogenic seizures with the epileptogenic focus localized in the inferior colliculus (IC). The sound-induced seizures exhibit a short latency (7–9 s), which implies innate protein disturbances in the IC as a basis for seizure susceptibility and generation. Here, we aim to study the protein profile in the GASH/Sal IC in comparison to controls. Protein samples from the IC were processed for enzymatic digestion and then analyzed by mass spectrometry in Data-Independent Acquisition mode. After identifying the proteins using the UniProt database, we selected those with differential expression and performed ontological analyses, as well as gene-protein interaction studies using bioinformatics tools. We identified 5254 proteins; among them, 184 were differentially expressed proteins (DEPs), with 126 upregulated and 58 downregulated proteins, and 10 of the DEPs directly related to epilepsy. Moreover, 12 and 7 proteins were uniquely found in the GASH/Sal or the control. The results indicated a protein profile alteration in the epileptogenic nucleus that might underlie the inborn occurring audiogenic seizures in the GASH/Sal model. In summary, this study supports the use of bioinformatics methods in proteomics to delve into the relationship between molecular-level protein mechanisms and the pathobiology of rodent models of audiogenic seizures.

Evaluation of miR-526b-3p, miR-1179, miR-3529-3p, miR-5011-5p as potential diagnostic biomarkers in isolated cervical dystonia

BACKGROUND

Cervical dystonia (CD) also named spasmodic torticollis is the most common type of focal dystonias and characterized by abnormal head, neck, and shoulder movements due to involuntary muscular spasm. Although CD is mostly idiopathic, to date, several genes have been associated with CD. However, to the best of our knowledge, microRNAs (miRNAs) which are interacted with CD-associated genes have been not evaluated yet. miRNAs are regulatory small non-coding RNAs and are suggested as potential biomarkers for many diseases through their stability in clinical samples. Therefore, we aimed to assess the expression levels of miRNAs (miR-526b-3p, miR-1179, miR-3529-3p, miR-5011-5p) which are targeted the CD-associated genes, and evaluate their performance as diagnostic biomarkers.

METHODS

Peripheral blood samples were obtained from 30 patients with isolated CD (ICD) and 25 healthy controls. The expression levels of miR-526b-3p, miR-1179, miR-3529-3p, and miR-5011-5p were analyzed via quantitative real-time PCR (qRT-PCR), and receiver operating characteristic (ROC) curves were generated to evaluate the diagnostic values.

RESULTS

miR-526b-3p, miR-1179, and miR-3529-3p were significantly up-regulated while miR-5011-5p was significantly down-regulated in ICD patients compared to healthy controls. ROC analysis revealed that all miRNAs, especially miR-1179 and miR-3529-3p were statistically significant with the area under the curve (AUC) of 0.905 and 0.933, respectively.

CONCLUSION

Altered expression levels of aforementioned miRNAs may be associated with CD pathogenesis. Our findings suggest using these four miRNAs as remarkable biomarkers in the diagnosis of ICD.

Cation-Chloride Cotransporters KCC2 and NKCC1 as Therapeutic Targets in Neurological and Neuropsychiatric Disorders

Neurological diseases including Alzheimer's, Huntington's disease, Parkinson's disease, Down syndrome and epilepsy, and neuropsychiatric disorders such as schizophrenia, are conditions that affect not only individuals but societies on a global scale. Current therapies offer a means for small symptomatic relief, but recently there has been increasing demand for therapeutic alternatives. The γ-aminobutyric acid (GABA)ergic signaling system has been investigated for developing new therapies as it has been noted that any dysfunction or changes to this system can contribute to disease progression. Expression of the K-Cl-2 (KCC2) and N-K-C1-1 (NKCC1) cation-chloride cotransporters (CCCs) has recently been linked to the disruption of GABAergic activity by affecting the polarity of GABA_A receptor signaling. KCC2 and NKCC1 play a part in multiple neurological and neuropsychiatric disorders, making them a target of interest for potential therapies. This review explores current research suggesting the pathophysiological role and therapeutic importance of KCC2 and NKCC1 in neuropsychiatric and neurological disorders.

Age-Related microRNA Overexpression in Lafora Disease Male Mice Provides Links between Neuroinflammation and Oxidative Stress

Lafora disease is a rare, fatal form of progressive myoclonus epilepsy characterized by continuous neurodegeneration with epileptic seizures, characterized by the intracellular accumulation of aberrant polyglucosan granules called Lafora bodies. Several works have provided numerous evidence of molecular and cellular alterations in neural tissue from experimental mouse models deficient in either laforin or malin, two proteins related to the disease. Oxidative stress, alterations in proteostasis, and deregulation of inflammatory signals are some of the molecular alterations underlying this condition in both KO animal models. Lafora bodies appear early in the animal's life, but many of the aforementioned molecular aberrant processes and the consequent neurological symptoms ensue only as animals age. Here, using small RNA-seq and quantitative PCR on brain extracts from laforin and malin KO male mice of different ages, we show that two different microRNA species, miR-155 and miR-146a, are overexpressed in an age-dependent manner. We also observed altered expression of putative target genes for each of the microRNAs studied in brain extracts. These results open the path for a detailed dissection of the molecular consequences of laforin and malin deficiency in brain tissue, as well as the potential role of miR-155 and miR-146a as specific biomarkers of disease progression in LD.

MicroRNA-127 promotes anti-microbial ability in porcine alveolar macrophages via S1PR3/TLR signaling pathway

BACKGROUND

As Actinobacillus pleuropneumonniae (APP) infection causes considerable losses in the pig industry, there is a growing need to develop effective therapeutic interventions that leverage host immune defense mechanisms to combat these pathogens.

OBJECTIVES

To demonstrate the role of microRNA (miR)-127 in controlling bacterial infection against APP. Moreover, to investigate a signaling pathway in macrophages that controls the production of anti-microbial peptides.

METHODS

Firstly, we evaluated the effect of miR-127 on APP-infected pigs by cell count/enzyme-linked immunosorbent assay (ELISA). Then the impact of miR-127 on immune cells was detected. The cytokines tumor necrosis factor (TNF)-α and interleukin (IL)-6 were evaluated by ELISA. The expression of cytokines (anti-microbial peptides [AMPs]) was assessed using quantitative polymerase chain reaction. The expression level of IL-6, TNF-α and p-P65 were analyzed by western blot. The expression of p65 in the immune cells was investigated by immunofluorescence.

RESULTS

miR-127 showed a protective effect on APP-infected macrophage. Moreover, the protective effect might depend on its regulation of macrophage bactericidal activity and the generation of IL-22, IL-17 and AMPs by targeting sphingosine-1-phosphate receptor3 (SIPR3), the element involved in the Toll-like receptor (TLR) cascades.

CONCLUSIONS

Together, we identify that miR-127 is a regulator of S1PR3 and then regulates TLR/nuclear factor-κB signaling in macrophages with anti-bacterial acticity, and it might be a potential target for treating inflammatory diseases caused by APP.

Therapeutic Implications of microRNAs in Depressive Disorders: A Review

MicroRNAs are hidden players in complex psychophysical phenomena such as depression and anxiety related disorders though the activation and deactivation of multiple proteins in signaling cascades. Depression is classified as a mood disorder and described as feelings of sadness, loss, or anger that interfere with a person’s everyday activities. In this review, we have focused on exploration of the significant role of miRNAs in depression by affecting associated target proteins (cellular and synaptic) and their signaling pathways which can be controlled by the attachment of miRNAs at transcriptional and translational levels. Moreover, miRNAs have potential role as biomarkers and may help to cure depression through involvement and interactions with multiple pharmacological and physiological therapies. Taken together, miRNAs might be considered as promising novel therapy targets themselves and may interfere with currently available antidepressant treatments.

Aberrant Expression of Serum MicroRNA-153 and -199a in Generalized Epilepsy and its Correlation with Drug Resistance

Background:

Epilepsy is one of the common neurological disorders affecting approximately 50 million people worldwide. Despite the recent introduction of new antiepileptic drugs, about one-third of patients with epilepsy have seizures refractory to pharmacotherapy. Early recognition of patients with drug-resistant epilepsy may help direct these patients to appropriate nonpharmacological treatment.

Purpose:

The possible use of serum microRNAs (miRNAs) as noninvasive biomarkers has been explored in various brain diseases, including epilepsy. In this study, we are aiming at analyzing the expression levels of circulating miRNA-153 and miRNA-199a in patients with generalized epilepsy and their correlation with drug resistance.

Methods:

Our study comprised 40 patients with generalized epilepsy and 20 healthy controls. 22 patients were drug-resistant and 18 patients were drug-responsive. The expression levels of miRNA-153 and -199a in serum were analyzed using quantitative real-time polymerase chain reaction. Data analysis was done by IBM SPSS Statistics 20.0.

Results:

The expression of miRNA-153 and -199a in serum was significantly downregulated in patients with generalized epilepsy compared with that of the healthy control ( P < .001). Combined expression level of serum miRNA-153 and -199a had a sensitivity of 85% and a specificity of 90% in the diagnosis of generalized epilepsy. Furthermore, the expression levels of miRNA-153 and -199a were significantly decreased in drug-resistant patients compared to the drug-responsive group, and the combination of both markers gave the best results in differentiating between the two groups.

Conclusion:

We suggest that serum miRNAs-153 and -199a expression levels could be potential noninvasive biomarkers supporting the diagnosis of generalized epilepsy. Moreover, they could be used for the early detection of refractory generalized epilepsy.

miR-146a/KLF4 axis in epileptic mice: a novel regulator of synaptic plasticity involving STAT3 signaling

OBJECTIVE

This study is aimed to investigate the mechanism of miR-146a/KLF4 axis regarding epilepsy seizure and synaptic plasticity.

METHODS

Pentylenetetrazol (PTZ)-kindling mouse model of epilepsy was established and evaluated by Racine's scale. PTZ-treated mice were subjected to stereotactic injection of miR-146a antagomir and pre-KLF4 to verify the role of miR-146a and KLF4 in mice. Primary hippocampal neurons from fetal mouse were isolated and identified through immunofluorescence for microtubule-associated protein (MAP)-2. Cellular models of epilepsy were prepared using magnesium-free extracellular fluid and then the neurons were transfected with miR-146a antagomir, miR-146a agomir, miR-146a agomir + pre-KLF4, AG490 (an inhibitor of STAT3 signal pathway) or miR-146a agomir + AG490. The binding site between miR-146a and KLF4 was predicted and identified. The expression levels of miR-146a, KLF4, CREB, Synaptotagmin-11 (SYT11), and STAT3-related proteins were measured in addition to the morphology of neurons and length of neurite. The severity of synaptic plasticity was assessed according to the levels of CREB and SYT11.

RESULTS

The expression of miR-146a was elevated and KLF4 expression was decreased in epileptic mice. Stereotactic injection of miR-146a antagomir and pre-KLF4 reduced the seizure scores of epileptic mice. Transfection of miR-146a antagomir or pre-KLF4 could attenuate synaptic plasticity in epileptic mice and epileptic cellular models. miR-146a can negatively regulate KLF4 in epileptic cellular models to mediate synaptic plasticity. Epilepsy was attenuated in AG490 and miR-146a agomir + AG490 groups compared with that in Model group.

CONCLUSION

miR-146a inhibits KLF4 to activate STAT3, thus promoting synaptic plasticity in epileptic mice.

Detection of Deregulated miRNAs in Childhood Epileptic Encephalopathies

The term "epileptic encephalopathy" is used to describe a possible relationship between epilepsy and developmental delay. The pathogenesis of developmental encephalopathies, independent of epilepsy, can be defined by genetic control mechanisms. The aim of this study was to investigate the use of miRNAs as serum biomarkers for the determination and discrimination of epileptic encephalopathies. Whole blood samples obtained from 54 individuals in 2 groups designated as epileptic encephalopathy patients' group (n = 24) and healthy controls (n = 30) were included in this study. The expression levels of 10 miRNAs were determined using qRT-PCR. After the determination of expression levels, the correlation of upregulated miRNA levels and Ki67 index was calculated using Pearson correlation test. The comparison of epileptic encephalopathy patients' group with healthy controls revealed the upregulation of one miRNAs (hsa-miR-324-5p) and downregulation of three miRNAs (hsa-miR-146a-5p, hsa-miR-138-5p, hsa-miR-187-3p). It has been determined that miRNAs with altered expression are an important factor in the formation of epileptic seizures and seizure-induced neuronal death. The fact that processes that play a key role in epiloptogenesis are under the control of miRNAs causes miRNAs to become meta-controllers of gene expression in the brain. We thought that further studies are needed to prove that especially hsa-miR-146a-5p, hsa-miR-138-5p, and hsa-miR-187-3p can be used as epileptic encephalopathy biomarkers. The detection of disease-specific miRNAs could contribute to the development of precision treatments.

Pathological Targets for Treating Temporal Lobe Epilepsy: Discoveries From Microscale to Macroscale

Temporal lobe epilepsy (TLE) is one of the most common and severe types of epilepsy, characterized by intractable, recurrent, and pharmacoresistant seizures. Histopathology of TLE is mostly investigated through observing hippocampal sclerosis (HS) in adults, which provides a robust means to analyze the related histopathological lesions. However, most pathological processes underlying the formation of these lesions remain elusive, as they are difficult to detect and observe. In recent years, significant efforts have been put in elucidating the pathophysiological pathways contributing to TLE epileptogenesis. In this review, we aimed to address the new and unrecognized neuropathological discoveries within the last 5 years, focusing on gene expression (miRNA and DNA methylation), neuronal peptides (neuropeptide Y), cellular metabolism (mitochondria and ion transport), cellular structure (microtubule and extracellular matrix), and tissue-level abnormalities (enlarged amygdala). Herein, we describe a range of biochemical mechanisms and their implication for epileptogenesis. Furthermore, we discuss their potential role as a target for TLE prevention and treatment. This review article summarizes the latest neuropathological discoveries at the molecular, cellular, and tissue levels involving both animal and patient studies, aiming to explore epileptogenesis and highlight new potential targets in the diagnosis and treatment of TLE.

miR-190-5p Alleviates Myocardial Ischemia-Reperfusion Injury by Targeting PHLPP1

Objective

Myocardial ischemia-reperfusion (I/R) injury (MIRI) refers to the more serious myocardial injury after blood flow recovery, which seriously affects the prognosis of patients with ischemic cardiomyopathy. This study explored the new targets for MIRI treatment by investigating the effects of miR-190-5p and its downstream target on the structure and function of myocardial cells.

Methods

We injected agomir miR-190-5p into the tail vein of rats to increase the expression of miR-190-5p in rat myocardial cells and made an I/R rat model by coronary artery occlusion. We used 2,3,5-triphenyl tetrazolium chloride staining, lactate dehydrogenase (LDH) detection, echocardiography, and hematoxylin-eosin (HE) staining to determine the degree of myocardial injury in I/R rats. In addition, we detected the expression of inflammatory factors and apoptosis-related molecules in rat serum and myocardial tissue to determine the level of inflammation and apoptosis in rat myocardium. Finally, we determined the downstream target of miR-190-5p by Targetscan system and dual luciferase reporter assay.

Results

The expression of miR-190-5p in an I/R rat myocardium was significantly lower than that in normal rats. After treatment of I/R rats with agomir miR-190-5p, the ischemic area of rat myocardium and the concentration of LDH decreased. The results of echocardiography and HE staining also found that overexpression of miR-190-5p improved the structure and function of rat myocardium. miR-190-5p was also found to improve the viability of H9c2 cells in vitro and reduce the level of apoptosis of H9c2 cells. The results of Targetscan system and dual luciferase reporter assay found that miR-190-5p targeted to inhibit pleckstrin homology domain leucine-rich repeat protein phosphatase 1 (PHLPP1). In addition, inhibition of PHLPP1 was found to improve the viability of H9c2 cells.

Conclusion

Therefore, miR-190-5p can reduce the inflammation and apoptosis of myocardium by targeting PHLPP1, thereby alleviating MIRI.

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.

Circulating level of microRNA-142-5p is a potential biomarker for predicting in-stent restenosis: a case-control study

Background

Patients who receive percutaneous coronary intervention (PCI) have different chances of developing in-stent restenosis (ISR). To date, no predictable biomarker can be applied in the clinic. MicroRNAs (miRNAs or miRs) play critical roles in transcription regulation, and their circulating levels were reported to have potential as clinical biomarkers.

Methods

In total, 93 coronary stent-implanted patients without pregnancy, liver or renal dysfunction, malignancy, hemophilia, or autoimmune diseases were recruited in this clinical study. All recruited participants were divided into an ISR group (n = 45) and a non-ISR group (n = 48) based on their restenotic status as confirmed by cardiologists at the first follow-up visit (6 months after surgery). Blood samples of all participants were harvested to measure circulating levels of miRNA candidates (miR-132, miR-142-5p, miR-15b, miR-24-2, and miR-424) to evaluate whether these circulating miRNAs can be applied as predictive biomarkers of ISR.

Results

Our data indicated that circulating levels of miR-142-5p were significantly higher in the ISR population, and results from the receiver operating characteristic (ROC) curve analysis also demonstrated superior discriminatory ability of miR-142-5p in predicting patients’ restenotic status. In addition, circulating levels of miR-15b, miR-24-2, and miR-424 had differential expressions in participants with diabetes, hyperlipidemia, and hypertension, respectively.

Conclusions

The current study revealed that the circulating level of miR-142-5p has potential application as a clinical biomarker for predicting the development of ISR in stent-implanted patients.

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.

The role of exosomal microRNAs in central nervous system diseases

MicroRNAs (miRNA), endogenous non-coding RNAs approximately 22 nucleotides long, regulate gene expression by mediating translational inhibition or mRNA degradation. Exosomes are a tool for intercellular transmission of information in which miRNA exchange plays an important role. Under pathophysiological conditions in the central nervous system (CNS), cellular transmission of exosomal miRNAs can regulate signaling pathways. Exosomal miRNAs are involved in the occurrence and development of diverse CNS diseases, such as traumatic brain injury, spinal cord injury, stroke, neurodegenerative diseases, epilepsy, and glioma. The use of exosomes as transport vehicles for certain miRNAs provides a novel therapeutic strategy for CNS diseases. Furthermore, the exosomes in body fluids change with the occurrence of diseases, indicating that subtle changes in physiological and pathological processes in vivo could be recognized by analyzing exosomes. Exosomal analysis is expected to act as a novel tool for diagnosis and prediction of neurological diseases. In this review, we present the current understanding of the implications of miRNAs in CNS diseases and summarize the role and mechanism of action of exosomal miRNA in nervous system disease models.

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.

MicroRNA expression profiling after recurrent febrile seizures in rat and emerging role of miR-148a-3p/SYNJ1 axis

Febrile seizures (FSs) are common neurological disorders in both infants and children, although the precise underlying mechanism remains to be explored, especially in the expression pattern and function of microRNAs (miRNAs). In this report, we aimed to screen new potential miRNAs and examine the role of miR-148a-3p in hippocampal neurons in FS rats via Synaptojanin-1 (SYNJ1). Thirty rats were randomly divided into the normal and FS model groups, which were investigated by miRNA array. This process identified 31 differentially expressed (20 upregulated and 11 downregulated) miRNAs and potential miRNA target genes. In addition, hippocampal neurons were assigned into five groups for different transfections. Apoptosis was detected by TUNEL and flow cytometry. SYNJ1 was identified as a target gene of miR-148-3p. In vitro experiments revealed that inhibition of miR-148a-3p decreased neuronal cell apoptosis. Moreover, overexpression of miR-148a-3p resulted in activation of PI3K/Akt signaling pathway and the apoptosis of hippocampal neurons. MiR-148a-3p inhibitor could reverse the above events. Taken together, our data demonstrated that the hippocampal miRNA expression profiles of a rat model of FS provide a large database of candidate miRNAs and neuron-related target genes. Furthermore, miR-148a-3p acted as a apoptosis enhcaner via the activation of the SYNJ1/PI3K/Akt signaling pathway, highlighting a potential therapeutic target in the treatment of infants with hyperthermia-induced brain injury.

MicroRNAs as Immune Regulators of Inflammation in Children with Epilepsy

Epilepsy is a chronic clinical syndrome of brain function which is caused by abnormal discharge of neurons. MicroRNAs (miRNAs) are small non-coding RNAs which act post-transcriptionally to regulate negatively protein levels. They affect neuroinflammatory signaling, glial and neuronal structure and function, neurogenesis, cell death, and other processes linked to epileptogenesis. The aim of this study was to explore the possible role of miR-125a and miR-181a as regulators of inflammation in epilepsy through investigating their involvement in the pathogenesis of epilepsy, and their correlation with the levels of inflammatory cytokines. Thirthy pediatric patients with epilepsy and 20 healthy controls matched for age and sex were involved in the study. MiR-181a and miR-125a expression were evaluated in plasma of all subjects using qRT-PCR. In addition, plasma levels of inflammatory cytokines (IFN-γ and TNF-) were determined using ELISA. Our findings indicated significantly lower expression levels of miR-125a (P=0.001) and miR-181a (P=0.001) in epileptic patients in comparison with controls. In addition, the production of IFN-γ and TNF- was non-significantly higher in patients with epilepsy in comparison with the control group. Furthermore, there were no correlations between miR-125a and miR-181a with the inflammatory cytokines (IFN-γ and TNF-) in epileptic patients. MiR-125a and miR-181a could be involved in the pathogenesis of epilepsy and could serve as diagnostic biomarkers for pediatric patients with epilepsy.

CircHivep2 contributes to microglia activation and inflammation via miR-181a-5p/SOCS2 signalling in mice with kainic acid-induced epileptic seizures

Epilepsy is a chronic brain disease characterized by recurrent seizures. Circular RNA (circRNA) is a novel family of endogenous non‐coding RNAs that have been proposed to regulate gene expression. However, there is a lack of data on the role of circRNA in epilepsy. In this study, the circRNA profiles were evaluated by microarray analysis. In total, 627 circRNAs were up‐regulated, whereas 892 were down‐regulated in the hippocampus in mice with kainic acid (KA)‐induced epileptic seizures compared with control. The expression of circHivep2 was significantly down‐regulated in hippocampus tissues of mice with KA‐induced epileptic seizures and BV‐2 microglia cells upon KA treatment. Bioinformatics analysis predicted that circHivep2 interacts with miR‐181a‐5p to regulate SOCS2 expression, which was validated using a dual‐luciferase reporter assay. Moreover, overexpression of circHivep2 significantly inhibited KA‐induced microglial activation and the expression of inflammatory factors in vitro, which was blocked by miR‐181a‐5p, whereas circHivep2 knockdown further induced microglia cell activation and the release of pro‐inflammatory proteins in BV‐2 microglia cells after KA treatment. The application of circHivep2+ exosomes derived from adipose‐derived stem cells (ADSCs) exerted significant beneficial effects on the behavioural seizure scores of mice with KA‐induced epilepsy compared to control exosomes. The circHivep2+ exosomes also inhibited microglial activation, the expression of inflammatory factors, and the miR‐181a‐5p/SOCS2 axis in vivo. Our results suggest that circHivep2 regulates microglia activation in the progression of epilepsy by interfering with miR‐181a‐5p to promote SOCS2 expression, indicating that circHivep2 may serve as a therapeutic tool to prevent the development of epilepsy.

P2X7 Receptor-Dependent microRNA Expression Profile in the Brain Following Status Epilepticus in Mice

The ionotropic ATP-gated P2X7 receptor is an important contributor to inflammatory signaling cascades via the release of Interleukin-1β, as well as having roles in cell death, neuronal plasticity and the release of neurotransmitters. Accordingly, there is interest in targeting the P2X7 receptor for the treatment of epilepsy. However, the signaling pathways downstream of P2X7 receptor activation remain incompletely understood. Notably, recent studies showed that P2X7 receptor expression is controlled, in part, by microRNAs (miRNAs). Here, we explored P2X7 receptor-dependent microRNA expression by comparing microRNA expression profiles of wild-type (wt) and P2X7 receptor knockout mice before and after status epilepticus. Genome-wide microRNA profiling was performed using hippocampi from wt and P2X7 receptor knockout mice following status epilepticus induced by intra-amygdala kainic acid. This revealed that the genetic deletion of the P2X7 receptor results in distinct patterns of microRNA expression. Specifically, we found that in vehicle-injected control mice, the lack of the P2X7 receptor resulted in the up-regulation of 50 microRNAs and down-regulation of 35 microRNAs. Post-status epilepticus, P2X7 receptor deficiency led to the up-regulation of 44 microRNAs while 13 microRNAs were down-regulated. Moreover, there was only limited overlap among identified P2X7 receptor-dependent microRNAs between control conditions and post-status epilepticus, suggesting that the P2X7 receptor regulates the expression of different microRNAs during normal physiology and pathology. Bioinformatic analysis revealed that genes targeted by P2X7 receptor-dependent microRNAs were particularly overrepresented in pathways involved in intracellular signaling, inflammation, and cell death; processes that have been repeatedly associated with P2X7 receptor activation. Moreover, whereas genes involved in signaling pathways and inflammation were common among up- and down-regulated P2X7 receptor-dependent microRNAs during physiological and pathological conditions, genes associated with cell death seemed to be restricted to up-regulated microRNAs during both physiological conditions and post-status epilepticus. Taken together, our results demonstrate that the P2X7 receptor impacts on the expression profile of microRNAs in the brain, thereby possibly contributing to both the maintenance of normal cellular homeostasis and pathological processes.

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

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

microRNAs in Autism Spectrum Disorders

BACKGROUND

Efforts to unravel the extensive impact of the non-coding elements of the human genome on cell homeostasis and pathological processes have gained momentum over the last couple of decades. miRNAs refer to short, often 18-25 nucleotides long, non-coding RNA molecules which can regulate gene expression. Each miRNA can regulate several mRNAs.

METHODS

This article reviews the literature on the roles of miRNAs in autism.

RESULTS

Considering the fact that ~ 1% of the human DNA encodes different families of miRNAs, their overall impact as critical regulators of gene expression in the mammalian brain should be immense. Though the autism spectrum disorders (ASDs) are predominantly genetic in nature and several candidate genes are already identified, the highly heterogeneous and multifactorial nature of the disorder makes it difficult to identify common genetic risk factors. Several studies have suggested that the environmental factors may interact with the genetic factors to increase the risk. miRNAs could possibly be one of those factors which explain this link between genetics and the environment.

CONCLUSION

In the present review, we have summarized our current knowledge on miRNAs and their complex roles in ASD, and also on their therapeutic applications.

Genome-wide microRNA profiling in brain and blood samples in a mouse model of epileptogenesis

OBJECTIVES

This study profiled circulating and hippocampal microRNAs (miRNAs) to identify alterations associated with the risk of epileptogenesis in a mouse temporal lobe epilepsy model.

METHODS

Next-generation sequencing was performed to examine the changes in miRNA expression 24 h after pilocarpine-induced status epilepticus (SE) in C57BL/6NCrl mice using both blood and hippocampus samples. Differentially expressed miRNAs were identified from SE animals and matched controls that failed to develop SE after receiving equal doses of pilocarpine (NS animals). Blood and brain miRNA profiles were then compared to identify circulating miRNA alterations reflecting the changes in the brain.

RESULTS

We identified 3 miRNAs that were significantly up-regulated and 4 miRNAs that were significantly down-regulated in the blood of SE animals compared with NS animals. When hippocampal miRNAs of SE animals and NS animals were compared, 5 miRNAs were up-regulated and 4 were down-regulated. Of these, miR-434-3p and miR-133a-3p were observed to have greatest changes in both blood and brain of SE animals.

SIGNIFICANCE

This study extends current knowledge of changes in miRNAs associated with epileptogenesis by profiling miRNAs in SE and NS animals in an experimental temporal lobe epilepsy model. The study was designed to allow non-specific changes due to the activation of muscarinic cholinergic receptors in peripheral organs by pilocarpine to be ruled out. Significantly altered circulating miRNAs that reflect changes in the brain during epileptogenesis after SE have the potential to be developed as prognostic biomarkers for epileptogenesis.

Modulation of NMDA receptor by miR-219 in the amygdala and hippocampus of patients with mesial temporal lobe epilepsy

Mesial temporal lobe epilepsy with hippocampal sclerosis is the most frequent form of focal epilepsy in adults, and it is often refractory to drug treatment. Regardless of the efforts on developing new antiepileptic drugs for refractory cases, studies suggest a need for better understanding the molecular bases of epilepsy. The microRNAs have been progressively investigated as potential targets for both epilepsy mechanisms elucidation and treatment. Therefore, the goal of this study was to evaluate the differential expression of miR-219, miR-181b, and miR-195, previously described as regulators of the excitatory neurotransmitter receptors NMDA-R1 and AMPA-GluR2 and inhibitory neurotransmitter GABA_A (α2, β3, and γ2 subunits) in the amygdala and hippocampus of patients with mesial temporal lobe epilepsy. Based on genes and miRNAs' quantitative Polymerase Chain Reaction (qPCR) from 18 patients with epilepsy, our results showed an inverse relationship between miR-219 and NMDA-NR1 expression in both the amygdala and hippocampus in comparison to their expression in controls. NR1 and GluR2 were upregulated in the amygdala of epileptic patients. Low miR-195 expression was observed in the amygdala of patients with epilepsy. Our findings indicate that miR-219 has a possible regulatory role in excitatory neurotransmission in patients with epilepsy, contributing to the new avenue of miRNA biology in drug-resistant epilepsy, reserving huge potential for future applications and clinical interventions in conjunction with existing therapies.

Transcriptional Regulation of Channelopathies in Genetic and Acquired Epilepsies

Epilepsy is a common neurological disorder characterized by recurrent uncontrolled seizures and has an idiopathic “genetic” etiology or a symptomatic “acquired” component. Genetic studies have revealed that many epilepsy susceptibility genes encode ion channels, including voltage-gated sodium, potassium and calcium channels. The high prevalence of ion channels in epilepsy pathogenesis led to the causative concept of “ion channelopathies,” which can be elicited by specific mutations in the coding or promoter regions of genes in genetic epilepsies. Intriguingly, expression changes of the same ion channel genes by augmentation of specific transcription factors (TFs) early after an insult can underlie acquired epilepsies. In this study, we review how the transcriptional regulation of ion channels in both genetic and acquired epilepsies can be controlled, and compare these epilepsy “ion channelopathies” with other neurodevelopmental disorders.

Differential expression of miR-34a, 451, 1260, 1275 and 1298 in the neocortex of patients with mesial temporal lobe epilepsy

Mesial temporal lobe epilepsy (mTLE) is the most common epilepsy syndrome which will eventually become pharmacologically intractable partial-onset seizures. Regulation of gene expression is an important process in the development of this pathology where microRNAs (miRs) are involved. The role of miRs has been widely studied in the hippocampus of rodents and patients. However, little is known about its differential expression in other brain regions such as the neocortex. The temporal neocortex plays a major role in the generation and propagation of seizures and in synaptic disruption, impairing the excitatory and inhibitory balance. Therefore, we assessed the expression of miR-146a, 34a, 1260, 1275, 1298, 451, 132 and 142-3p in the neocortex of 12 patients with mTLE and compared them with miRs expression found in 10 control samples. We noted a significant decrease in the expression of miR-34a and 1298 in patients with mTLE and a -1.49 to -7.0 fold change respectively compared with controls. Conversely, we observed a significant increase in the expression of miR-451, 1260 and 1275 in patients with a 25.67, 4.09 and a 7.07 fold change respectively compared to controls. Using Pearson correlation, we explored the association between the clinical features of mTLE patients and controls with miRs expression. In the control group we found a significant correlation only with age and miR-146a expression (r = 0.733). The analysis of mTLE patients showed a negative correlation between expression of miR-1260 (r = -0.666) and miR-1298 (r = -0.651) and age. Furthermore, we found a positive correlation between miR-146a expression with seizure frequency (r = 0.803) and a positive correlation between miR-146a and 451 expression with number of antiepileptic drugs used for presurgical treatment (r = 0.715 and 0.611 respectively), thus suggesting a positive correlation with disease severity. These miRs are associated with biological processes such as apoptosis, drug resistance, inflammation, inhibitory and excitatory synaptic transmission, axonal guidance and signaling of neurotrophins. Therefore, deepening our understanding of the targets involved in these miRs will help to elucidate the role of the neocortex in epilepsy.

MicroRNA inhibition upregulates hippocampal A-type potassium current and reduces seizure frequency in a mouse model of epilepsy

Epilepsy is often associated with altered expression or function of ion channels. One example of such a channelopathy is the reduction of A-type potassium currents in the hippocampal CA1 region. The underlying mechanisms of reduced A-type channel function in epilepsy are unclear. Here, we show that inhibiting a single microRNA, miR-324-5p, which targets the pore-forming A-type potassium channel subunit Kv4.2, selectively increased A-type potassium currents in hippocampal CA1 pyramidal neurons in mice. Resting membrane potential, input resistance and other potassium currents were not altered. In a mouse model of acquired chronic epilepsy, inhibition of miR-324-5p reduced the frequency of spontaneous seizures and interictal epileptiform spikes supporting the physiological relevance of miR-324-5p-mediated control of A-type currents in regulating neuronal excitability. Mechanistic analyses demonstrated that microRNA-induced silencing of Kv4.2 mRNA is increased in epileptic mice leading to reduced Kv4.2 protein levels, which is mitigated by miR-324-5p inhibition. By contrast, other targets of miR-324-5p were unchanged. These results suggest a selective miR-324-5p-dependent mechanism in epilepsy regulating potassium channel function, hyperexcitability and seizures.

The current and emerging therapeutic approaches in drug-resistant epilepsy management

Epilepsy is a neurologic disorder consisting of recurrent spontaneous seizures. Antiepileptic drugs administration is the most commonly used therapeutic strategy in the management of epilepsy. However, 20-30% of epilepsy patients have seizure episodes that are not controlled by these medicines (drug-resistant epilepsy). The management of drug-resistant epilepsy, especially in the children, is challenging and can cause economic and social problems, and lower the patients' quality of life, cognition, and mood. Several therapeutic approaches for drug-resistant epilepsy are available including surgical methods, neurostimulation treatments, and diet therapies which lead to diminishing the epileptic seizures. An increasing number of novel and potential therapeutic approaches such as gene therapy, gene editing, cell therapy, exosome therapy, and molecular network targeting have also been explored. The present study is aimed to review these current and emerging therapeutic approaches for drug-resistant epilepsy.

Expression of plasma microRNA-145-5p and its correlation with clinical features in patients with refractory epilepsy

PURPOSE

The potential of microRNAs (miRNAs) as biomarkers has been explored in various brain diseases, including epilepsy. In this study, we are aiming to analyze the aberrant expression of miRNA-145-5p in patients with refractory epilepsy, and to further explore the correlation with clinical features.

METHODS

The study cohort comprised 40 patients with refractory epilepsy and 42 healthy controls. MiRNA-145-5p expression levels in plasma were analyzed by quantitative real-time polymerase chain reaction (qRT-PCR). Data analysis was performed using IBM SPSS Statistics 22.0.

RESULTS

Compared with healthy controls, the expression of miRNA-145-5p in plasma was downregulated significantly in the patients with refractory epilepsy (1.180 ± 1.036 vs. 1.541 ± 0.936, p = 0.033) and mesial temporal lobe epilepsy (MTLE) (0.517 ± 0.483 vs. 1.541 ± 0.936, p = 0.004). ROC analysis showed that the area under the curve (AUC) was 0.632 (95%CI: 0.508-0.755; P = 0.040) in refractory epilepsy and 0.829 (95%CI: 0.702-0.955; P = 0.001) in MTLE. Furthermore, the expression of miRNA-145-5p was positively correlated with earlier age at epilepsy onset, more frequent seizures and past history.

CONCLUSIONS

We suggested that decreased expression of miRNA-145-5p could be a potential non-invasive biomarker for early detection and clinical evaluation of refractory epilepsy. However, further studies are still required.

[Difficulties in the diagnosis, prognosis and treatment of genetic epileptic encephalopathies: the view of a neurologist]

Genetic epileptic encephalopathies are a rather wide spectrum of childhood epilepsies with onset of epilepsy in the first 1.5-2 years of life, regression or delayed psychomotor and speech development and 'massive' epileptiform activity on electroencephalogram (EEG). The review discusses the difficulties of choosing the optimal method of genetic examination, problems with the interpretation of the results obtained, the formulation of the diagnosis, the determination of the prognosis of the course and targeted therapy. It is emphasized that the interpretation of the identified genetic variants is not an easy task, requiring close interaction between specialists in molecular genetics, bioinformatics, neurology and clinical genetics. The possibilities of targeted treatment of genetic epileptic encephalopathies are still limited, but knowledge of the genetic cause of epilepsy allows making a more informed choice of the treatment.

microRNAs Sculpt Neuronal Communication in a Tight Balance That Is Lost in Neurological Disease

Since the discovery of the first microRNA 25 years ago, microRNAs (miRNAs) have emerged as critical regulators of gene expression within the mammalian brain. miRNAs are small non-coding RNAs that direct the RNA induced silencing complex to complementary sites on mRNA targets, leading to translational repression and/or mRNA degradation. Within the brain, intra- and extracellular signaling events tune the levels and activities of miRNAs to suit the needs of individual neurons under changing cellular contexts. Conversely, miRNAs shape neuronal communication by regulating the synthesis of proteins that mediate synaptic transmission and other forms of neuronal signaling. Several miRNAs have been shown to be critical for brain function regulating, for example, enduring forms of synaptic plasticity and dendritic morphology. Deficits in miRNA biogenesis have been linked to neurological deficits in humans, and widespread changes in miRNA levels occur in epilepsy, traumatic brain injury, and in response to less dramatic brain insults in rodent models. Manipulation of certain miRNAs can also alter the representation and progression of some of these disorders in rodent models. Recently, microdeletions encompassing MIR137HG, the host gene which encodes the miRNA miR-137, have been linked to autism and intellectual disability, and genome wide association studies have linked this locus to schizophrenia. Recent studies have demonstrated that miR-137 regulates several forms of synaptic plasticity as well as signaling cascades thought to be aberrant in schizophrenia. Together, these studies suggest a mechanism by which miRNA dysregulation might contribute to psychiatric disease and highlight the power of miRNAs to influence the human brain by sculpting communication between neurons.

Regulation of Ion Channels by MicroRNAs and the Implication for Epilepsy

PURPOSE OF REVIEW

The goal of this focused review is to describe recent studies supporting a critical role of microRNAs in the regulation of ion channels and discuss the resulting implications for the modulation of neuronal excitability in epilepsy.

RECENT FINDINGS

MicroRNA-induced silencing of ion channels has been shown in several different studies in recent years, and some of these reports suggest a prominent role in epilepsy. The ion channels regulated by microRNAs include ligand- and voltage-gated channels and are not only limited to the central nervous system but have also been found in the peripheral nervous system. Ion channel-targeting microRNAs can regulate the intrinsic excitability of neurons, and thus influence entire networks in the brain. Their dysregulation in epilepsy may contribute to the disease phenotype. More research is needed to better understand the molecular mechanisms of how microRNAs regulate ion channels to control neuronal excitability, and how these processes are altered in epilepsy.

Mice with miR-146a deficiency develop severe gouty arthritis via dysregulation of TRAF 6, IRAK 1 and NALP3 inflammasome

BACKGROUND

MicroRNAs (miRNAs) serve as important regulators of inflammatory and immune responses and are implicated in several immune disorders including gouty arthritis. The expression of miR-146a is upregulated in the peripheral blood mononuclear cells of patients with inter-critical gout when compared to normouricemic and hyperuricemic controls and those patients with acute gout flares. However, the role of miR-146a in the development of gout remains unknown. Here, we used miR-146a knockout (KO) mice to test miR-146a function in a monosodium urate (MSU)-induced gouty arthritis model.

METHODS

The footpad or ankle joint of miR-146a KO and wild-type (WT) mice were injected with an MSU suspension to induce acute gouty arthritis. Bone marrow-derived macrophages (BMDMs) were stimulated with MSU and the gene expression of miR-146a; interleukin 1 beta (IL-1β); tumor necrosis factor-α (TNF-α); and the NACHT, LRR and PYD domains-containing protein 3 (NALP3) inflammasome was evaluated. TNF-α and IL-1β protein levels in BMDMs were assessed by fluorescence-activated cell sorting and western blot analyses. Gene and protein levels of TNF receptor-associated factor 6 (TRAF6) and IL-1 receptor-associated kinase (IRAK1), the targets of miR-146a, were also measured.

RESULTS

Significantly increased paw swelling and index and ankle joint swelling were observed in miR-146a KO mice compared to WT controls after MSU treatment. MiR-146a expression in BMDMs from WT mice was dramatically upregulated at 4 h following MSU stimulation. Additionally, the expression of IL-1β, TNF-α, and NALP3 was higher in BMDMs from miR-146a KO mice after exposure to MSU crystals compared to those from WT mice. Consistent with the observed gene expression, the IL-1β and TNF-α proteins were upregulated in miR-146a KO mice. Additionally quantitative RT-PCR and western blot demonstrated that TRAF6 and IRAK1 were dramatically upregulated in BMDMs from miR-146 KO mice compared to those from WT mice.

CONCLUSIONS

Collectively, these observations suggest that miR-146a provides negative feedback regulation of gouty arthritis development and lack of miR-146a enhances gouty arthritis via upregulation of TRAK6, IRAK-1, and the NALP3 inflammasome function.