A Comprehensive Examination of the Role of Epigenetic Factors in Multiple Sclerosis.

According to various research, the risk of multiple sclerosis (MS) is strongly influenced by genetic variations. Population, familial, and molecular studies provide strong empirical support for a polygenic pattern of inheritance, mainly due to relatively common allelic variants in the general population. The strongest MS susceptibility locus, which was unmistakably identified in tested populations, is the major histocompatibility complex on chromosome 6p21.3. However, the effect of a given predisposing variant remains modest, so there is the possibility that multiple gene-gene and/or gene-environment interactions could significantly increase the contribution of specific variants to the overall genetic risk. Furthermore, as is known, susceptibility genes can be subject to epigenetic modifications, which greatly increase the complexity of MS heritability. Investigating epigenetic and environmental factors can provide new opportunities for the molecular basis of the MS, which shows complicated pathogenesis. Although studies of epigenetic changes in MS only began in the last decade, a growing body of literature suggests that these may be involved in the development of MS. Here, we summarize recent studies regarding epigenetic changes related to MS initiation and progression. Furthermore, we discuss how current studies address important clinical questions and how future studies could be used in clinical practice.

Extracellular Vesicles in Multiple Sclerosis: Their Significance in the Development and Possible Applications as Therapeutic Agents and Biomarkers.

Extracellular vesicles (EVs) are "micro-shuttles" that play a role as mediators of intercellular communication. Cells release EVs into the extracellular environment in both physiological and pathological conditions and are involved in intercellular communication, due to their ability to transfer proteins, lipids, and nucleic acids, and in the modulation of the immune system and neuroinflammation. Because EVs can penetrate the blood-brain barrier and move from the central nervous system to the peripheral circulation, and vice versa, recent studies have shown a substantial role for EVs in several neurological diseases, including multiple sclerosis (MS). MS is a demyelinating disease where the main event is caused by T and B cells triggering an autoimmune reaction against myelin constituents. Recent research has elucidate the potential involvement of extracellular vesicles (EVs) in the pathophysiology of MS, although, to date, their potential role both as agents and therapeutic targets in MS is not fully defined. We present in this review a summary and comprehensive examination of EVs' involvement in the pathophysiology of multiple sclerosis, exploring their potential applications as biomarkers and indicators of therapy response.

Circulating miRNAs in progressive supranuclear palsy: Recent evidence and future challenges.

Numerous studies have highlighted the importance of microRNA (miRNAs) in neurodegenerative diseases. However, the miRNA profiles in progressive supranuclear palsy (PSP) patients have been rarely reported. Recent evidence suggested a possible role of some dysregulated miRNAs in the cerebrospinal fluid (CSF) of PSP patients in the pathogenesis of the disease.

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

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

Hyper-religiosity and visual hallucinations in a patient with frontotemporal dementia carrying a double variant in GRN gene.

Introduction: Hyper-religiosity has been reported in patients affected by frontotemporal dementia (FTD) with asymmetrical, predominantly right-sided frontotemporal atrophy. Case report: We report a FTD patient carrying a double genetic variant (p.Cys139Arg and c.*78C > T) in the progranulin (GRN) gene who showed an unusual clinical phenotype characterized by hyper-religiosity behavior and visual hallucinations with exclusively religious content. Noteworthy, this patient exhibited a slow clinical and radiological rate of disease progression and a predominantly left-sided frontotemporal atrophy. Discussion and conclusion: The simultaneous presence of these GRN variants in our FTD patient with predominant atrophy in the left (dominant) hemisphere could determine the unusual phenotype with hyper-religiosity and visual hallucinations with exclusively religious content and influence the slow rate of disease progression.

Exosomal miRNA as peripheral biomarkers in Parkinson's disease and progressive supranuclear palsy: A pilot study.

INTRODUCTION: Parkinson's disease (PD), a progressive neurodegenerative disease, can be misdiagnosed with atypical conditions such as Progressive Supranuclear Paralysis (PSP) due to overlapping clinical features. MicroRNAs (miRNAs) are small non-coding RNAs with a key role in post-transcriptional gene regulation. The aim was to identify a set of differential exosomal miRNAs biomarkers, which may aid in diagnosis. METHODS: We analyzed the serum level of 188 miRNAs in a discovery set, by using RTqPCR based TaqMan assay, in a small cohort of healthy controls, PD and PSP patients. Subsequently, the differentially expressed miRNAs, between PSP and PD patients, were further tested in a larger and independent cohort of 33 healthy controls, 40 PD and 20 PSP patients. The most accurate diagnostic exosomal miRNAs classifiers were identified in a logistic regression model. RESULTS: A statistically significant set of three exosomal miRNAs: miR-21-3p, miR-22-3p and miR-223-5p, discriminated PD from HC (area under the curve of 0.75), and a set of three exosomal miRNAs, miR-425-5p, miR-21-3p, and miR-199a-5p, discriminated PSP from PD with good diagnostic accuracy (area under the curve of 0.86). Finally, the classifier that best discriminated PSP from PD consisted of six exosomal miRNAs (area under the curve = 0.91), with diagnostic sensitivity and specificity of 0.89 and 0.90, respectively. CONCLUSIONS: Based on our analysis, these data showed that exosomal miRNAs could act as biomarkers to differentiate between PSP and PD.

Roles of Non-Coding RNAs as Novel Diagnostic Biomarkers in Parkinson's Disease.

Parkinson's disease (PD) is the second most common neurodegenerative disorder, affecting 5%of the elderly population. Currently, the diagnosis of PD is mainly based on clinical features and no definitive diagnostic biomarkers have been identified. The discovery of biomarkers at the earliest stages of PD is of extreme interest. This review focuses on the current findings in the field of circulating non-coding RNAs in PD. We briefly describe the more established circulating biomarkers in PD and provide a more thorough review of non-coding RNAs, in particular microRNAs, long non-coding RNAs and circular RNAs, differentially expressed in PD, highlighting their potential for being considered as biomarkers for diagnosis. Together, these studies hold promise for the use of peripheral biomarkers for the diagnosis of PD.

Circulating microRNA: The Potential Novel Diagnostic Biomarkers to Predict Drug Resistance in Temporal Lobe Epilepsy, a Pilot Study.

MicroRNAs (miRNAs) are small noncoding RNAs that have emerged as new potential epigenetic biomarkers. Here, we evaluate the efficacy of six circulating miRNA previously described in the literature as biomarkers for the diagnosis of temporal lobe epilepsy (TLE) and/or as predictive biomarkers to antiepileptic drug response. We measured the differences in serum miRNA levels by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) assays in a cohort of 27 patients (14 women and 13 men; mean ± SD age: 43.65 ± 17.07) with TLE compared to 20 healthy controls (HC) matched for sex, age and ethnicity (11 women and 9 men; mean ± SD age: 47.5 ± 9.1). Additionally, patients were classified according to whether they had drug-responsive (n = 17) or drug-resistant (n = 10) TLE. We have investigated any correlations between miRNAs and several electroclinical parameters. Three miRNAs (miR-142, miR-146a, miR-223) were significantly upregulated in patients (expressed as average expression ± SD). In detail, miR-142 expression was 0.40 ± 0.29 versus 0.16 ± 0.10 in TLE patients compared to HC (t-test, p < 0.01), miR-146a expression was 0.15 ± 0.11 versus 0.07 ± 0.04 (t-test, p < 0.05), and miR-223 expression was 6.21 ± 3.65 versus 1.23 ± 0.84 (t-test, p < 0.001). Moreover, results obtained from a logistic regression model showed the good performance of miR-142 and miR-223 in distinguishing drug-sensitive vs. drug-resistant TLE. The results of this pilot study give evidence that miRNAs are suitable targets in TLE and offer the rationale for further confirmation studies in larger epilepsy cohorts.

Exosomal miRNAs as Potential Diagnostic Biomarkers in Alzheimer's Disease.

Alzheimer's disease (AD), a neurodegenerative disease, is linked to a variety of internal and external factors present from the early stages of the disease. There are several risk factors related to the pathogenesis of AD, among these exosomes and microRNAs (miRNAs) are of particular importance. Exosomes are nanocarriers released from many different cell types, including neuronal cells. Through the transfer of bioactive molecules, they play an important role both in the maintenance of physiological and in pathological conditions. Exosomes could be carriers of potential biomarkers useful for the assessment of disease progression and for therapeutic applications. miRNAs are small noncoding endogenous RNA sequences active in the regulation of protein expression, and alteration of miRNA expression can result in a dysregulation of key genes and pathways that contribute to disease development. Indeed, the involvement of exosomal miRNAs has been highlighted in various neurodegenerative diseases, and this opens the possibility that dysregulated exosomal miRNA profiles may influence AD disease. The advances in exosome-related biomarker detection in AD are summarized. Finally, in this review, we highlight the use of exosomal miRNAs as essential biomarkers in preclinical and clinical studies in Alzheimer's disease, also taking a look at their potential clinical value.

Potential Role of miRNAs as Theranostic Biomarkers of Epilepsy.

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

Exosome-associated miRNA profile as a prognostic tool for therapy response monitoring in multiple sclerosis patients.

Multiple sclerosis (MS) is an autoimmune pathology leading to neurodegeneration. Because of the complexity and heterogenic etiology of this disease, diagnosis and treatment for individual patients are challenging. Exosome-associated microRNAs (miRNAs) have recently emerged as a new class of diagnostic biomarkers involved in both autoimmune and neurologic disorders. Interesting new evidence has emerged showing that circulating miRNAs are dysregulated in MS body fluids, including serum, plasma, and cerebrospinal fluid. We hypothesized that exosome-associated miRNAs could present a readily accessible blood-based assay for MS disease. We detected expression of miRNAs by quantitative PCR on a small cohort of MS patients. We analyzed circulating exosome-associated miRNAs of MS patients before and after therapy and found that 14 exosome-associated miRNAs were significantly down-regulated, while 2 exosome-associated miRNAs were significantly up-regulated in IFN-ß-treated relapsing-remitting MS patients with response to therapy compared to those without response. We identified a serum miRNA panel that could be used to monitor the response to IFN-ß therapy. Overall, these data suggest that circulating exosome-associated miRNA profiling could represent an easily detectable biomarker of disease and treatment response.-Manna, I., Iaccino, E., Dattilo, V., Barone, S., Vecchio, E., Mimmi, S., Filippelli, E., Demonte, G., Polidoro, S., Granata, A., Scannapieco, S., Quinto, I., Valentino, P., Quattrone, A. Exosome-associated miRNA profile as a prognostic tool for therapy response monitoring in multiple sclerosis patients.

An SNP site in pri-miR-124, a brain expressed miRNA gene, no contribution to mesial temporal lobe epilepsy in an Italian sample.

Mesial temporal lobe epilepsy (MTLE) is the most common type of refractory epilepsy and is usually associated with hippocampal sclerosis (Hs). The pathogenesis of MTLE involves many biological pathways, some of which seem to be regulated by microRNAs (miRNAs). Increasing evidence shows that single nucleotide polymorphisms (SNPs) or mutations in miRNAs sequence may affect the processing and function of miRNAs and participate in the occurrence of diseases. In this study, the effect of the SNP of one neuronal miRNA, miR-124, on susceptibility to MTLE was investigated using a case control study. To understand the role, a common C/G polymorphism designated rs531564 in the molecular mechanisms of MTLE, we sought to determine whether this genetic variant could influence susceptibility to disease in a cohort of 307 MTLE patients and 306 healthy controls, using TaqMan allelic discrimination assay, on an Applied Biosystems PCR platform. No statistically significant differences were found in the allele or genotype distributions of the miR-124 rs531564 polymorphism among MTLE patients and MTLE-free control subjects (p > 0.05). Our results demonstrate that this SNP has no major role in genetic susceptibility to MTLE, at least in the population studied here.

DEPDC5 mutations are not a frequent cause of familial temporal lobe epilepsy.

Mutations in the DEPDC5 (DEP domain-containing protein 5) gene are a major cause of familial focal epilepsy with variable foci (FFEVF) and are predicted to account for 12-37% of families with inherited focal epilepsies. To assess the clinical impact of DEPDC5 mutations in familial temporal lobe epilepsy, we screened a collection of Italian families with either autosomal dominant lateral temporal epilepsy (ADLTE) or familial mesial temporal lobe epilepsy (FMTLE). The probands of 28 families classified as ADLTE and 17 families as FMTLE were screened for DEPDC5 mutations by whole exome or targeted massive parallel sequencing. Putative mutations were validated by Sanger sequencing. We identified a DEPDC5 nonsense mutation (c.918C>G; p.Tyr306*) in a family with two affected members, clinically classified as FMTLE. The proband had temporal lobe seizures with prominent psychic symptoms (déjà vu, derealization, and forced thoughts); her mother had temporal lobe seizures, mainly featuring visceral epigastric auras and anxiety. In total, we found a single DEPDC5 mutation in one of (2.2%) 45 families with genetic temporal lobe epilepsy, a proportion much lower than that reported in other inherited focal epilepsies.

Polymorphism of the multidrug resistance 1 gene MDR1/ABCB1 C3435T and response to antiepileptic drug treatment in temporal lobe epilepsy.

PURPOSE: A synonymous C to T variant at position 3435 (c.3435C>T) is one common polymorphism of the multidrug resistant 1 (MDR1) gene, which encodes the major transmembrane efflux transporter P-glycoprotein. It has been suggested that this polymorphism, and more specifically the 3435CC genotype, may be associated with the response to antiepileptic drug treatment. Here we wished to examine the role of such a candidate variant in a cohort of 175 patients (98 women and 76 men; mean ± SD age: 47.90 ± 17.64) with temporal lobe epilepsy (TLE). METHODS: Patients were classified according to whether they had drug-responsive (n=134) or drug-resistant (n=41) epilepsy. We also enrolled 175 healthy controls (93 women and 82 men; mean ± SD age: 72.5 ± 6.8), matched for sex and ethnicity. RESULTS: Patients and controls were genotyped for detection of the 3435C>T polymorphism, but the analysis showed no significant association between the CC genotype and the risk of drug-resistant epilepsy. CONCLUSION: These findings rule out the MDR1 c.3435C>T polymorphism having a major role or increasing the risk of drug-resistance suggesting a revision is required to determine the contribution of this polymorphism in predicting drug response in epilepsy.

Autosomal dominant lateral temporal epilepsy (ADLTE): absence of chromosomal rearrangements in LGI1 gene.

Mutations of leucine-rich, glioma inactivated 1 (LGI1) gene are found in about half of the families with autosomal dominant lateral temporal epilepsy (ADLTE). More recently a LGI1 heterozygous microdeletion was found in a single ADLTE family, suggesting that submicroscopic chromosomal abnormalities should be investigated in cases negative for LGI1 mutations. This study examines whether microdeletions and duplications of the LG1 gene occurred in eight ADLTE families and 20 sporadic patients that were negative for LGI1 mutations. Multiplex ligation-dependent probe amplification (MLPA) was applied to detect potential deletions and duplications of LGI1 gene. In all patients, MLPA analysis did not reveal any pathogenic changes in the LGI1 gene. Chromosomal rearrangements involving the LGI1 gene were not identified in our series of familial or sporadic LTE. These results further illustrate the considerable genetic heterogeneity for ADLTE, despite the relatively homogeneous clinical picture. There are as yet undiscovered mechanisms underlying ADLTE.

No evidence for a role of the coding variant of the Toll-like receptor 4 gene in temporal lobe epilepsy.

PURPOSE: There is evidence that inflammatory mechanisms play a role in the pathogenesis of temporal lobe epilepsy (TLE). Coding variants in Toll-like receptor 4 (TLR4) gene have been reported to be associated with inflammatory diseases. The aim of this study was to determine whether a functional polymorphism rs4986790 in the TLR4 gene is associated with susceptibility and clinical features of TLE. METHODS: A total of 345 patients with TLE and 370 age-matched controls were genotyped using TaqMan Allelic Discrimination assays, on an Applied Biosystems PCR platform. RESULTS: There was no significant difference in allele frequency or genotype of TLR4 between TLE patients and controls. Moreover, the clinical characteristics of these patients were unrelated to the presence of this polymorphism. CONCLUSION: Our data suggest that rs4986790 in the TLR4 gene is unlikely to influence significantly the risk of developing TLE or its severity.

Failure to confirm association of a polymorphism in KCNMB4 gene with mesial temporal lobe epilepsy.

A recent study has implicated a tagging single nucleotide polymorphism (SNP) rs398702 located 3' of KCNMB4 (encoding calcium-activated potassium channel, subfamily M subunit beta 4) as a possible susceptibility allele for mesial temporal lobe epilepsy (mTLE). Such a finding warrants a further well-powered study in additional carefully phenotyped cohorts. Here we examined the role of the SNP (rs398702) in a cohort of 332 patients (182 women and 150 men; mean±SD age: 47.06±18.12) who had diagnoses of mTLE. None of the patients had a mass lesion, malformations of cortical development, or traumatic brain injury. Brain MRI study revealed hippocampal sclerosis (Hs) in 86/332 (26%) patients. Most patients (254/332, 76%) patients had drug-responsive mTLE. We also enrolled 335 healthy controls (164 women and 171 men; mean±SD age: 48.20±21.90), matched for age, sex and ethnicity. All patients and controls were Caucasian and were born in Italy. The genotype distribution of the SNP rs398702 in patients and controls was within Hardy-Weinberg equilibrium (p>0.05). There was no statistically significant difference in the genotype or allelic frequencies between patients and controls (p=0.878 and p=0.666 respectively). Moreover, such a variant did not influence the main clinical characteristics of mTLE, the presence of Hs or responsiveness to antiepileptic drugs. In conclusion, our data suggest that the rs398702 variant in the KCNMB4 gene is unlikely to influence significantly the risk of developing mTLE or its severity. They further highlight the importance of replication to confirm the validity of association study results.

The BDNF Val66Met polymorphism has opposite effects on memory circuits of multiple sclerosis patients and controls.

Episodic memory deficits are frequent symptoms in Multiple Sclerosis and have been associated with dysfunctions of the hippocampus, a key region for learning. However, it is unclear whether genetic factors that influence neural plasticity modulate episodic memory in MS. We thus studied how the Brain Derived Neurotrophic Factor Val(66)Met genotype, a common polymorphism influencing the hippocampal function in healthy controls, impacted on brain networks underlying episodic memory in patients with Multiple Sclerosis. Functional magnetic resonance imaging was used to assess how the Brain Derived Neurotrophic Factor Val(66)Met polymorphism modulated brain regional activity and functional connectivity in 26 cognitively unimpaired Multiple Sclerosis patients and 25 age- and education-matched healthy controls while performing an episodic memory task that included encoding and retrieving visual scenes. We found a highly significant group by genotype interaction in the left posterior hippocampus, bilateral parahippocampus, and left posterior cingulate cortex. In particular, Multiple Sclerosis patients homozygous for the Val(66) allele, relative to Met(66) carriers, showed greater brain responses during both encoding and retrieval while the opposite was true for healthy controls. Furthermore, a robust group by genotype by task interaction was detected for the functional connectivity between the left posterior hippocampus and the ipsilateral posterior cingulate cortex. Here, greater hippocampus-posterior cingulate cortex connectivity was observed in Multiple Sclerosis Met(66) carriers relative to Val(66) homozygous during retrieval (but not encoding) while, again, the reverse was true for healthy controls. The Val(66)Met polymorphism has opposite effects on hippocampal circuitry underlying episodic memory in Multiple Sclerosis patients and healthy controls. Enhancing the knowledge of how genetic factors influence cognitive functions may improve the clinical management of memory deficits in patients with Multiple Sclerosis.