Circular RNAs: Biogenesis, Functions, and Role in Myocardial Hypertrophy.

Circular RNAs (circRNAs) are a large class of endogenous single-stranded covalently closed RNA molecules. High-throughput RNA sequencing and bioinformatic algorithms have identified thousands of eukaryotic circRNAs characterized by high stability and tissue-specific expression pattern. Recent studies have shown that circRNAs play an important role in the regulation of physiological processes in the norm and in various diseases, including cardiovascular disorders. The review presents current concepts of circRNA biogenesis, structural features, and biological functions, describes the methods of circRNA analysis, and summarizes the results of studies on the role of circRNAs in the pathogenesis of hypertrophic cardiomyopathy, the most common inherited heart disease.

Regulation of SMAD Signaling Pathway by miRNAs Associated with Myocardial Fibrosis: In silico Analysis of Target Gene Networks.

Hypertrophic cardiomyopathy (HCM) is a hereditary heart disease caused by mutations in the sarcomere genes, which is accompanied by myocardial fibrosis leading to progressive heart failure and arrhythmias. Recent studies suggest that the HCM development involves dysregulation of gene expression. Among the molecules involved in this process are microRNAs (miRNAs), which are short non-coding RNAs. Typically, one miRNA regulates several target genes post-transcriptionally, hence, it might be difficult to determine the role of a particular miRNA in the disease pathogenesis. In this study, using the PubMed database, we selected 15 miRNAs whose expression is associated with myocardial fibrosis, one of the critical pathological processes in HCM. We then used an earlier developed algorithm to search in silico for the signaling pathways regulated by these miRNAs and found that ten of them participate in the regulation of the TGF-ß/SMAD signaling pathway. At the same time, among the SMAD signaling pathway genes, the target of the most identified miRNAs was the MYC gene, which is involved in the development of fibrosis in some tissues. In our earlier work, we found that the TGF-ß/SMAD pathway is also regulated by a set of other miRNAs associated with the myocardial hypertrophy in HCM. The fact that two sets of miRNAs identified in two independent bioinformatic studies are involved in the regulation of the same signaling pathway indicates that the SMAD signaling cascade is indeed a key element in the regulation of pathological processes in HCM. The obtained data might contribute to understanding pathological processes underlying HCM development.

Circulating miR-499a-5p Is a Potential Biomarker of MYH7-Associated Hypertrophic Cardiomyopathy.

Hypertrophic cardiomyopathy (HCM) is the most common inherited myocardial disease with significant genetic and phenotypic heterogeneity. To search for novel biomarkers, which could increase the accuracy of HCM diagnosis and improve understanding of its phenotype formation, we analyzed the levels of circulating miRNAs­stable non-coding RNAs involved in post-transcriptional gene regulation. Performed high throughput sequencing of miRNAs in plasma of HCM patients and controls pinpointed miR-499a-5p as one of 35 miRNAs dysregulated in HCM. Further investigation on enlarged groups of individuals showed that its level was higher in carriers of pathogenic/likely pathogenic (P/LP) variants in MYH7 gene compared to controls (fold change, FC = 8.9; p < 0.0001). Just as important, carriers of variants in MYH7 gene were defined with higher miRNA levels than carriers of variants in the MYBPC3 gene (FC = 14.1; p = 0.0003) and other patients (FC = 4.1; p = 0.0008). The receiver operating characteristic analysis analysis showed the ability of miR-499a-5p to identify MYH7 variant carriers with the HCM phenotype with area under the curve value of 0.95 (95% confidence interval: 0.88−1.03, p = 0.0004); sensitivity and specificity were 0.86 and 0.91 (cut-off = 0.0014). Therefore, miR-499a-5p could serve as a circulating biomarker of HCM, caused by P/LP variants in MYH7 gene.

Novel Genes Involved in Hypertrophic Cardiomyopathy: Data of Transcriptome and Methylome Profiling.

Hypertrophic cardiomyopathy (HCM) is the most common inherited heart disease; its pathogenesis is still being intensively studied to explain the reasons for the significant genetic and phenotypic heterogeneity of the disease. To search for new genes involved in HCM development, we analyzed gene expression profiles coupled with DNA methylation profiles in the hypertrophied myocardia of HCM patients. The transcriptome analysis identified significant differences in the levels of 193 genes, most of which were underexpressed in HCM. The methylome analysis revealed 1755 nominally significant differentially methylated positions (DMPs), mostly hypomethylated in HCM. Based on gene ontology enrichment analysis, the majority of biological processes, overrepresented by both differentially expressed genes (DEGs) and DMP-containing genes, are involved in the regulation of locomotion and muscle structure development. The intersection of 193 DEGs and 978 DMP-containing genes pinpointed eight common genes, the expressions of which correlated with the methylation levels of the neighboring DMPs. Half of these genes (AUTS2, BRSK2, PRRT1, and SLC17A7), regulated by the mechanism of DNA methylation, were underexpressed in HCM and were involved in neurogenesis and synapse functioning. Our data, suggesting the involvement of innervation-associated genes in HCM, provide additional insights into disease pathogenesis and expand the field of further research.

Multiplex Analysis of Serum Cytokine Profiles in Systemic Lupus Erythematosus and Multiple Sclerosis.

Changes in cytokine profiles and cytokine networks are known to be a hallmark of autoimmune diseases, including systemic lupus erythematosus (SLE) and multiple sclerosis (MS). However, cytokine profiles research studies are usually based on the analysis of a small number of cytokines and give conflicting results. In this work, we analyzed cytokine profiles of 41 analytes in patients with SLE and MS compared with healthy donors using multiplex immunoassay. The SLE group included treated patients, while the MS patients were drug-free. Levels of 11 cytokines, IL-1b, IL-1RA, IL-6, IL-9, IL-10, IL-15, MCP-1/CCL2, Fractalkine/CX3CL1, MIP-1a/CCL3, MIP-1b/CCL4, and TNFa, were increased, but sCD40L, PDGF-AA, and MDC/CCL22 levels were decreased in SLE patients. Thus, changes in the cytokine profile in SLE have been associated with the dysregulation of interleukins, TNF superfamily members, and chemokines. In the case of MS, levels of 10 cytokines, sCD40L, CCL2, CCL3, CCL22, PDGF-AA, PDGF-AB/BB, EGF, IL-8, TGF-a, and VEGF, decreased significantly compared to the control group. Therefore, cytokine network dysregulation in MS is characterized by abnormal levels of growth factors and chemokines. Cross-disorder analysis of cytokine levels in MS and SLE showed significant differences between 22 cytokines. Protein interaction network analysis showed that all significantly altered cytokines in both SLE and MS are functionally interconnected. Thus, MS and SLE may be associated with impaired functional relationships in the cytokine network. A cytokine correlation networks analysis revealed changes in correlation clusters in SLE and MS. These data expand the understanding of abnormal regulatory interactions in cytokine profiles associated with autoimmune diseases.

Imprinted Genes and Multiple Sclerosis: What Do We Know?

Multiple sclerosis (MS) is a chronic autoimmune neurodegenerative disease of the central nervous system that arises from interplay between non-genetic and genetic risk factors. The epigenetics functions as a link between these factors, affecting gene expression in response to external influence, and therefore should be extensively studied to improve the knowledge of MS molecular mechanisms. Among others, the epigenetic mechanisms underlie the establishment of parent-of-origin effects that appear as phenotypic differences depending on whether the allele was inherited from the mother or father. The most well described manifestation of parent-of-origin effects is genomic imprinting that causes monoallelic gene expression. It becomes more obvious that disturbances in imprinted genes at the least affecting their expression do occur in MS and may be involved in its pathogenesis. In this review we will focus on the potential role of imprinted genes in MS pathogenesis.

Towards Understanding the Genetic Nature of Vasovagal Syncope.

Syncope, defined as a transient loss of consciousness caused by transient global cerebral hypoperfusion, affects 30-40% of humans during their lifetime. Vasovagal syncope (VVS) is the most common cause of syncope, the etiology of which is still unclear. This review summarizes data on the genetics of VVS, describing the inheritance pattern of the disorder, candidate gene association studies and genome-wide studies. According to this evidence, VVS is a complex disorder, which can be caused by the interplay between genetic factors, whose contribution varies from monogenic Mendelian inheritance to polygenic inherited predisposition, and external factors affecting the monogenic (resulting in incomplete penetrance) and polygenic syncope types.

Collapsing the list of myocardial infarction-related differentially expressed genes into a diagnostic signature.

BACKGROUND: Myocardial infarction (MI) is one of the most severe manifestations of coronary artery disease (CAD) and the leading cause of death from non-infectious diseases worldwide. It is known that the central component of CAD pathogenesis is a chronic vascular inflammation. However, the mechanisms underlying the changes that occur in T, B and NK lymphocytes, monocytes and other immune cells during CAD and MI are still poorly understood. One of those pathogenic mechanisms might be the dysregulation of intracellular signaling pathways in the immune cells. METHODS: In the present study we performed a transcriptome profiling in peripheral blood mononuclear cells of MI patients and controls. The machine learning algorithm was then used to search for MI-associated signatures, that could reflect the dysregulation of intracellular signaling pathways. RESULTS: The genes ADAP2, KLRC1, MIR21, PDGFD and CD14 were identified as the most important signatures for the classification model with L1-norm penalty function. The classifier output quality was equal to 0.911 by Receiver Operating Characteristic metric on test data. These results were validated on two independent open GEO datasets. Identified MI-associated signatures can be further assisted in MI diagnosis and/or prognosis. CONCLUSIONS: Thus, our study presents a pipeline for collapsing the list of differential expressed genes, identified by high-throughput techniques, in order to define disease-associated diagnostic signatures.

From miRNA Target Gene Network to miRNA Function: miR-375 Might Regulate Apoptosis and Actin Dynamics in the Heart Muscle via Rho-GTPases-Dependent Pathways.

MicroRNAs (miRNAs) are short, single-stranded, non-coding ribonucleic acid (RNA) molecules, which are involved in the regulation of main biological processes, such as apoptosis or cell proliferation and differentiation, through sequence-specific interaction with target mRNAs. In this study, we propose a workflow for predicting miRNAs function by analyzing the structure of the network of their target genes. This workflow was applied to study the functional role of miR-375 in the heart muscle (myocardium), since this miRNA was previously shown to be associated with heart diseases, and data on its function in the myocardium are mostly unclear. We identified PIK3CA, RHOA, MAPK3, PAFAH1B1, CTNNB1, MYC, PRKCA, ERBB2, and CDC42 as key genes in the miR-375 regulated network and predicted the possible function of miR-375 in the heart muscle, consisting mainly in the regulation of the Rho-GTPases-dependent signaling pathways. We implemented our algorithm for miRNA function prediction into a Python module, which is available at GitHub.

NGS-identified circulating miR-375 as a potential regulating component of myocardial infarction associated network.

Acute myocardial infarction (MI), the most severe type of coronary heart disease, is a leading cause of disability and mortality worldwide. In order to investigate the involvement of miRNAs in the pathologic processes related to MI, we performed the analysis of circulating miRNAs - stable short noncoding RNA molecules - in the peripheral blood plasma of MI patients compared to healthy controls (all persons were men and lived in European Russia) using next generation sequencing. We observed 20 miRNAs, which levels in plasma more than two-fold differed in MI patients (p < 0.05). Among them miR-208b and miR-375 passed threshold for multiple corrections (FC = 49.2, FDR-adjusted p-value = 0.0078 and FC = -6.4, FDR-adjusted p-value = 0.00076, respectively); these data were then validated using RT-qPCR (FC = 5.3, p-value = 0.028 and FC = -2.1, p-value = 0.0039, respectively). While for miR-208b we reidentified earlier observations, miR-375 was found to be associated with MI for the first time. To investigate the reasons for which miR-375 holds a special place among circulating miRNAs in MI, enrichment and network analyses of miR-375 target genes and their interactions were carried out. PIK3CA and TP53 genes, regulated by miR-375, were identified as the key players of MI disease module.

Genetic risk factors for myocardial infarction more clearly manifest for early age of first onset.

Epidemiological genetics established that heritability in determining the risk of myocardial infarction (MI) is substantially greater when MI occurs early in life. However, the genetic architecture of early-onset and late-onset MI was not compared. We analyzed genotype frequencies of SNPs in/near 20 genes whose protein products are involved in the pathogenesis of atherosclerosis in two groups of Russian patients with MI: the first group included patients with age of first MI onset <60 years (N = 230) and the second group with onset ≥60 years (N = 174). The control group of corresponding ethnicity consisted of 193 unrelated volunteers without cardiovascular diseases (93 individuals were over 60 years). We found that in the group of patients with age of onset <60 years, SNPs FGB rs1800788*T, TGFB1 rs1982073*T/T, ENOS rs2070744*C and CRP rs1130864*T/T were associated with risk of MI, whereas in patients with age of onset ≥60 years, only TGFB1 rs1982073*T/T was associated with risk of MI. Using APSampler software, we found composite markers associated with MI only in patients with early onset: FGB rs1800788*T + TGFB1 rs1982073*T; FGB rs1800788*T + LPL rs328*C + IL4 rs2243250*C; FGB rs1800788*T + ENOS rs2070744*C (Fisher p values of 1.4 × 10-6 to 2.2 × 10-5; the permutation p values of 1.1 × 10-5 to 3.0 × 10-4; ORs = 2.67-2.54). Alleles included in the combinations were associated with MI less significantly and with lower ORs than the combinations themselves. The result showed a substantially greater contribution of the genetic component in the development of MI if it occurs early in life, and demonstrated the usefulness of genetic testing for young people.

Pharmacogenetics of multiple sclerosis: personalized therapy with immunomodulatory drugs.

Pharmacogenetic (PG) studies aim to discover the individual genetic background that underlies the heterogeneity of treatment response, and thus find biomarkers for identification of individual patients who will benefit the most from the therapy administered or urgently require the alternate drug. Over the last decade, PG studies have made progress in terms of multiple sclerosis (MS), which is one of the most severe neurodegenerative diseases of the central nervous system. With the understanding of the role of the immune system in the pathogenesis of MS, a number of immunomodulatory drugs were developed for MS treatment management. However, clinical response to these disease-modifying therapies varies in individual patients. Interferon-ß and glatiramer acetate showed the most reliable long-term safety and remain among the first-line disease-modifying therapies for MS worldwide. Here, we will review the results of interferon-ß and glatiramer acetate PG studies with a detailed analysis of study design and approaches, their advantages and limitations, and future perspectives.

Genome-wide significant association with seven novel multiple sclerosis risk loci.

OBJECTIVE: A recent large-scale study in multiple sclerosis (MS) using the ImmunoChip platform reported on 11 loci that showed suggestive genetic association with MS. Additional data in sufficiently sized and independent data sets are needed to assess whether these loci represent genuine MS risk factors. METHODS: The lead SNPs of all 11 loci were genotyped in 10 796 MS cases and 10 793 controls from Germany, Spain, France, the Netherlands, Austria and Russia, that were independent from the previously reported cohorts. Association analyses were performed using logistic regression based on an additive model. Summary effect size estimates were calculated using fixed-effect meta-analysis. RESULTS: Seven of the 11 tested SNPs showed significant association with MS susceptibility in the 21 589 individuals analysed here. Meta-analysis across our and previously published MS case-control data (total sample size n=101 683) revealed novel genome-wide significant association with MS susceptibility (p<5×10(-8)) for all seven variants. This included SNPs in or near LOC100506457 (rs1534422, p=4.03×10(-12)), CD28 (rs6435203, p=1.35×10(-9)), LPP (rs4686953, p=3.35×10(-8)), ETS1 (rs3809006, p=7.74×10(-9)), DLEU1 (rs806349, p=8.14×10(-12)), LPIN3 (rs6072343, p=7.16×10(-12)) and IFNGR2 (rs9808753, p=4.40×10(-10)). Cis expression quantitative locus effects were observed in silico for rs6435203 on CD28 and for rs9808753 on several immunologically relevant genes in the IFNGR2 locus. CONCLUSIONS: This study adds seven loci to the list of genuine MS genetic risk factors and further extends the list of established loci shared across autoimmune diseases.

Variants of MicroRNA Genes: Gender-Specific Associations with Multiple Sclerosis Risk and Severity.

Multiple sclerosis (MS) is an autoimmune neuro-inflammatory disease arising from complex interactions of genetic, epigenetic, and environmental factors. Variations in genes of some microRNAs--key post-transcriptional regulators of many genes--can influence microRNAs expression/function and contribute to MS via expression changes of protein-coding target mRNA genes. We performed an association study of polymorphous variants of MIR146A rs2910164, MIR196A2 rs11614913, MIR499A rs3746444 MIR223 rs1044165 and their combinations with MS risk and severity. 561 unrelated patients with bout-onset MS and 441 healthy volunteers were enrolled in the study. We observed associations of MS risk with allele MIR223*T and combination (MIR223*T + MIR146A*G/G) carriage in the entire groups and in women at Bonferroni-corrected significance level (pcorr < 0.05). Besides, MIR146A*G/G association with MS was observed in women with nominal significance (pf = 0.025). No MS associations were found in men. A more severe MS course (MSSS value > 3.5) was associated with the carriage of MIR499A*C/T and, less reliably, of MIR499A*C (pcorr = 0.006 and pcorr = 0.024, respectively) and with the carriage of combinations (MIR499A*C/T + MIR196A2*C) and (MIR499A*C + MIR196A2*C) (pcorr = 0.00078 and pcorr = 0.0059, respectively). These associations also showed gender specificity, as they were not significant in men and substantially reinforced in women. The strongest association with MS severity was observed in women for combination (MIR499A*C/T + MIR196A2*C): pcorr = 4.43 × 10(-6) and OR = 3.23 (CI: 1.99-5.26).

Different genome-wide DNA methylation patterns in CD4+ T lymphocytes and CD14+ monocytes characterize relapse and remission of multiple sclerosis: Focus on GNAS.

BACKGROUND: Relapsing-remitting multiple sclerosis (RRMS) is a most common form of multiple sclerosis in which periods of neurological worsening are followed by periods of clinical remission. RRMS relapses are caused by an acute autoimmune inflammatory process, which can occur in any area of the central nervous system. Although development of exacerbation cannot yet be accurately predicted, various external factors are known to affect its risk. These factors may trigger the pathological process through epigenetic mechanisms of gene expression regulation, first of all, through changes in DNA methylation. METHODS: In the present work, we for the first time analyzed genome-wide DNA methylation patterns in CD4+ T lymphocytes and CD14+ monocytes of the same RRMS patients in relapse and remission. The effects of the differential methylation on gene expression were studied using qPCR. RESULTS: We found 743 differentially methylated CpG positions (DMPs) in CD4+ cells and only 113 DMPs in CD14+ cells. They were mostly hypermethylated in RRMS relapse in both cell populations. However, the proportion of hypermethylated DMPs (as well as DMPs located within or in close proximity to CpG islands) was significantly higher in CD4+ T lymphocytes. In CD4+ and CD14+ cells we identified 469 and 67 DMP-containing genes, respectively; 25 of them were common for two cell populations. When we conducted a search for differentially methylated genomic regions (DMRs), we found a CD4+ specific DMR hypermethylated in RRMS relapse (adj. p = 0.03) within the imprinted GNAS locus. Total level of the protein-coding GNAS transcripts in CD4+ T cells decreased significantly in the row from healthy control to RRMS remission and then to RRMS relapse (adj. p = 3.1 × 10-7 and 0.011, respectively). CONCLUSION: Our findings suggest that the epigenetic mechanism of DNA methylation in immune cells contributes to the development of RRMS relapse. Further studies are now required to validate these results and shed light on the molecular mechanisms underlying the observed GNAS methylation and expression changes.

Shared genetic architecture of COVID-19 and Alzheimer's disease.

The severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2) and the сoronavirus disease 2019 (COVID-19) have become a global health threat. At the height of the pandemic, major efforts were focused on reducing COVID-19-associated morbidity and mortality. Now is the time to study the long-term effects of the pandemic, particularly cognitive impairment associated with long COVID. In recent years much attention has been paid to the possible relationship between COVID-19 and Alzheimer's disease, which is considered a main cause of age-related cognitive impairment. Genetic predisposition was shown for both COVID-19 and Alzheimer's disease. However, the analysis of the similarity of the genetic architecture of these diseases is usually limited to indicating a positive genetic correlation between them. In this review, we have described intrinsic linkages between COVID-19 and Alzheimer's disease, pointed out shared susceptibility genes that were previously identified in genome-wide association studies of both COVID-19 and Alzheimer's disease, and highlighted a panel of SNPs that includes candidate genetic risk markers of the long COVID-associated cognitive impairment.

TGFB1 genetic polymorphisms and coronary heart disease risk: a meta-analysis.

BACKGROUND: Genetic variations in TGFB1 gene have been studied in relation to coronary heart disease (CHD) risk, but the results were inconsistent. METHODS: We performed a systematic review of published studies on the potential role of TGFB1 genetic variation in CHD risk. Articles that reported the association of TGFB1 genetic variants with CHD as primary outcome were searched via Medline and HuGE Navigator through July 2011. The reference lists from included articles were also reviewed. RESULTS: Data were available from 4 studies involving 1777 cases and 7172 controls for rs1800468, 7 studies involving 5935 cases and 10677 controls for rs1800469, 7 studies involving 6634 cases and 9620 controls for rs1982073, 5 studies involving 5452 cases and 9999 controls for rs1800471, and 4 studies involving 5143 cases and 4229 controls for rs1800472. The pooled odds ratios (ORs) for CHD among minor T allele carriers of rs1800469, minor C allele carriers of rs1982073, and minor C allele carriers of rs1800471 versus homozygous major allele carriers was 1.14 (95% confidence interval [CI]: 1.05-1.24), 1.18 (95% CI: 1.04-1.35), and 1.16 (95% CI: 1.02-1.32), respectively. No substantial heterogeneity for ORs was detected among the included Caucasian populations for all SNPs. However, for rs1800471, the statistical significance disappeared after adjusting for potential publication bias. No significant association was found between rs1800468 and rs1800472 variants and CHD risk. CONCLUSION: Minor allele carriers of two genetic variants (rs1800469 and rs1982073) in TGFB1 have a 15% increased risk of CHD.

Male-specific coordinated changes in expression of miRNA genes, but not other genes within the DLK1-DIO3 locus in multiple sclerosis.

The role of miRNAs, small non-coding regulatory RNAs, in the molecular mechanisms of multiple sclerosis (MS) development has been intensively studied. MiRNAs tend to be clustered within imprinted regions, and the largest number of miRNA genes is observed in the DLK1-DIO3 locus. Earlier using RNA-seq we identified sex-specific upregulation of the set of miRNA genes from this locus in peripheral blood mononuclear cells (PBMC) of treatment-naive relapsing-remitting MS (RRMS) patients. In the present study we set up to independently investigate the expression of a vast array of genes present in the DLK1-DIO3 imprinted locus. First, we analyzed the expression of miRNA genes, which levels in RRMS were mostly inconsistent based on RNA-seq data and not previously explored using qPCR. We identified that all selected miRNAs - miR-337-3p and -665 from 14q32.2 cluster and miR-370c, -380, -494, -654-3p, -300, -539, -668, and -323b-5p - were upregulated in MS men, but not women when compared to controls, regardless of conflicting RNA-seq data. The expression of miRNAs from the DLK1-DIO3 locus was highly correlated, indicating the existence of a common regulatory mechanism(s) that controls miRNA expression, regardless of the position of their genes within this region. Second, we performed the expression analysis of non-miRNA genes within the locus. The genes encoding proteins (DLK1, DIO3, RTL1), long non-coding RNAs (MEG3, MEG8, and MEG9) and small nucleolar RNAs (SNORD112, SNORD113-5, SNORD113-7, SNORD114-3, SNORD114-8, SNORD114-19) were not dysregulated in RRMS both in men and women. DNA methylation analysis of selected CpG sites within the differentially methylated regions IG-DMR, MEG3-DMR, and MEG8-DMR of the DLK1-DIO3 imprinted locus pointed out that they were not involved in the regulation of miRNA gene expression in RRMS, at least in PBMC population. The question of whether the observed changes in expression of miRNA genes (given that there is a constant expression of other non-miRNA genes of the DLK1-DIO3 locus) are involved in the development of RRMS or are they a consequence of the disease progress, remains open and needs further investigation.

Genome-wide DNA methylation profiling identifies epigenetic changes in CD4+ and CD14+ cells of multiple sclerosis patients.

Multiple sclerosis (MS) is a chronic autoimmune and degenerative disease of the central nervous system, which develops in genetically predisposed individuals upon exposure to environmental influences. Environmental triggers of MS, such as viral infections or smoking, were demonstrated to affect DNA methylation, and thus to involve this important epigenetic mechanism in the development of pathological process. To identify MS-associated DNA methylation hallmarks, we performed genome-wide DNA methylation profiling of two cell populations (CD4+ T-lymphocytes and CD14+ monocytes), collected from the same treatment-naive relapsing-remitting MS patients and healthy subjects, using Illumina 450 K methylation arrays. We revealed significant changes in DNA methylation for both cell populations in MS. In CD4+ cells of MS patients the majority of differentially methylated positions (DMPs) were shown to be hypomethylated, while in CD14+ cells - hypermethylated. Differential methylation of HLA-DRB1 gene in CD4+ and CD14+ cells was associated with carriage of DRB1*15 allele independently from the disease status. Besides, about 20% of identified DMPs were shared between two cell populations and had the same direction of methylation changes; they may be involved in basic epigenetic processes occuring in MS. These findings suggest that the epigenetic mechanism of DNA methylation in immune cells contributes to MS; further studies are now required to validate these results and understand their functional significance.

Global transcriptome profiling in peripheral blood mononuclear cells identifies dysregulation of immune processes in individuals with radiologically isolated syndrome.

The presence of brain/spinal white matter lesions typical for multiple sclerosis (MS) in asymptomatic individuals is known as 'radiologically isolated syndrome' (RIS). Taking into account that RIS patients are at high risk of MS development, the understanding of mechanisms underlying its pathogenesis is of great importance. In order to investigate RIS-specific transcription signature we performed high-throughput RNA-sequencing in peripheral blood mononuclear cells (PBMCs) of 8 RIS patients and 8 age- and sex-matched healthy controls. We identified 57 differentially expressed genes (DEGs), which levels differed by more than 2 times when comparing RIS patients to healthy controls (FDR p value < 0.05). Gene ontology enrichment analysis in the "biological process" category revealed 16 signaling pathways significantly overrepresented by identified DEGs. The most significant changes in gene expression in PBMCs of RIS patients occur in pathways involved in regulation of the immune response, cytokine and chemokine signaling, cytokine production, and leukocyte migration. In general, analyzing the global transcriptome we demonstrated the dysregulation of immune processes in PBMCs of RIS patients, confirming the current assumption that RIS represents the preclinical stage and/or subclinical form of MS.