1 4350 128 MIR-181A-5P IS A POTENTIAL CANDIDATE EPIGENETIC BIOMARKER IN MULTIPLE SCLEROSIS. MULTIPLE SCLEROSIS (MS) IS A CHRONIC INFLAMMATORY DISEASE OF THE CENTRAL NERVOUS SYSTEM (CNS) CHARACTERIZED BY DEMYELINATION AND AXONAL DEGENERATION. ABNORMAL EXPRESSION OF MICRORNAS (MIRNAS) PLAYS AN IMPORTANT ROLE IN MS PATHOLOGY. IN THIS COHORT STUDY, DIFFERENTIAL EXPRESSION OF THE FOUR MIRNAS (HSA-MIR-155-5P, HSA-MIR-9-5P, HSA-MIR-181A-5P, AND HSA-MIR-125B-5P) WAS INVESTIGATED IN 69 INDIVIDUALS, INCLUDING 39 MS PATIENTS (RELAPSING-REMITTING MS (RRMS), N = 27; SECONDARY PROGRESSIVE MS (SPMS), N = 12) AND 30 HEALTHY CONTROLS. IN SILICO ANALYSES REVEALED POSSIBLE GENES AND PATHWAYS SPECIFIC TO MIRNAS. PERIPHERAL BLOOD MIRNA EXPRESSIONS WERE DETECTED BY QUANTITATIVE REAL-TIME PCR (QPCR). HSA-MIR-181A-5P WAS DOWNREGULATED AND ASSOCIATED WITH INCREASED MS RISK (P = 0.012). THE OTHER THREE MIRNAS WERE UPREGULATED AND NOT ASSOCIATED WITH MS (P < 0.05). THE AREA UNDER THE CURVE (AUC) IS 0.779. IN SILICO ANALYSES SHOWED THAT HSA-MIR-181A-5P MAY PARTICIPATE IN MS PATHOLOGY BY TARGETING MAP2K1, CREB1, ATXN1, AND ATXN3 GENES IN INFLAMMATION AND NEURODEGENERATION PATHWAYS. THE CIRCULATORY HSA-MIR-181A-5P CAN REGULATE TARGET GENES, REVERSING THE MECHANISMS INVOLVED IN MS PATHOLOGIES SUCH AS PROTEIN UPTAKE AND PROCESSING, CELL PROLIFERATION AND SURVIVAL, INFLAMMATION, AND NEURODEGENERATION. THUS, THIS MIRNA COULD BE USED AS AN EPIGENOMIC-GUIDED DIAGNOSTIC TOOL AND FOR THERAPEUTIC PURPOSE. 2022 2 4590 38 NANOPORE SEQUENCING IDENTIFIES DIFFERENTIALLY METHYLATED GENES IN THE CENTRAL NERVOUS SYSTEM IN EXPERIMENTAL AUTOIMMUNE ENCEPHALOMYELITIS. MULTIPLE SCLEROSIS (MS) IS A CHRONIC AUTOIMMUNE-MEDIATED DEMYELINATING DISEASE OF THE CENTRAL NERVOUS SYSTEM (CNS) THAT MIGHT BE TRIGGERED BY ABERRANT EPIGENETIC CHANGES IN THE GENOME. DNA METHYLATION IS THE MOST STUDIED EPIGENETIC MECHANISM THAT PARTICIPATES IN MS PATHOGENESIS. HOWEVER, THE OVERALL METHYLATION LEVEL IN THE CNS OF MS PATIENTS REMAINS ELUSIVE. WE USED DIRECT LONG-READ NANOPORE DNA SEQUENCING AND CHARACTERIZED THE DIFFERENTIALLY METHYLATED GENES IN THE BRAIN FROM MICE WITH EXPERIMENTAL AUTOIMMUNE ENCEPHALOMYELITIS (EAE), AN ANIMAL MODEL OF MS. WE IDENTIFIED 163 HYPOMETHYLATED PROMOTERS AND 327 HYPERMETHYLATED PROMOTERS. THESE GENOMIC ALTERATIONS WERE LINKED TO VARIOUS BIOLOGICAL PROCESSES INCLUDING METABOLISM, IMMUNE RESPONSES, NEURAL ACTIVITIES, AND MITOCHONDRIAL DYNAMICS, ALL OF WHICH ARE VITAL FOR EAE DEVELOPMENT. OUR RESULTS INDICATE A GREAT POTENTIAL OF NANOPORE SEQUENCING IN IDENTIFYING GENOMIC DNA METHYLATION IN EAE AND PROVIDE IMPORTANT GUIDANCE FOR FUTURE STUDIES INVESTIGATING THE MS/EAE PATHOLOGY. 2023 3 4721 37 NONCODING RNAS IN MULTIPLE SCLEROSIS. MULTIPLE SCLEROSIS (MS), A CHRONIC INFLAMMATORY DEMYELINATING DISEASE OF THE CENTRAL NERVOUS SYSTEM, IS CHARACTERIZED BY AXONAL DEGENERATION AND GLIOSIS. ALTHOUGH THE CAUSES OF MS REMAIN UNKNOWN, GENE DYSREGULATION IN THE CENTRAL NERVOUS SYSTEM HAS BEEN ASSOCIATED WITH THE DISEASE PATHOGENESIS. AS SUCH, THE VARIOUS REGULATORS OF GENE EXPRESSION MAY BE CONTRIBUTING FACTORS. THE NONCODING (NC) RNAS HAVE PIQUED THE INTEREST OF MS RESEARCHERS DUE TO THEIR KNOWN FUNCTIONS IN HUMAN PHYSIOLOGY AND VARIOUS PATHOLOGICAL PROCESSES, DESPITE BEING GENERALLY CHARACTERIZED AS TRANSCRIPTS WITHOUT APPARENT PROTEIN-CODING CAPACITY. ACCUMULATING EVIDENCE HAS INDICATED THAT NCRNAS PARTICIPATE IN THE REGULATION OF MS BY ACTING AS EPIGENETIC FACTORS, ESPECIALLY THE LONG (L) NCRNAS AND THE MICRO (MI) RNAS, AND THEY ARE NOW RECOGNIZED AS KEY REGULATORY MOLECULES IN MS. IN THIS REVIEW, WE SUMMARIZE THE MOST CURRENT STUDIES ON THE CONTRIBUTION OF NCRNAS IN MS PATHOGENIC PROCESSES AND DISCUSS THEIR POTENTIAL APPLICATIONS IN THE DIAGNOSIS AND TREATMENT OF MS. 2018 4 4269 27 MICROBIAL DYSBIOSIS AND LACK OF SCFA PRODUCTION IN A SPANISH COHORT OF PATIENTS WITH MULTIPLE SCLEROSIS. BACKGROUND: MULTIPLE SCLEROSIS (MS) IS A CHRONIC, DEMYELINATING, AND IMMUNE-MEDIATED DISEASE OF THE CENTRAL NERVOUS SYSTEM CAUSED BY A COMBINATION OF GENETIC, EPIGENETIC, AND ENVIRONMENTAL FACTORS. THE INCIDENCE OF MS HAS INCREASED IN THE PAST SEVERAL DECADES, SUGGESTING CHANGES IN THE ENVIRONMENTAL RISK FACTORS. MUCH EFFORT HAS BEEN MADE IN THE DESCRIPTION OF THE GUT MICROBIOTA IN MS; HOWEVER, LITTLE IS KNOWN ABOUT THE DYSBIOSIS ON ITS FUNCTION. THE MICROBIOTA PRODUCES THOUSANDS OF BIOLOGICALLY ACTIVE SUBSTANCES AMONG WHICH ARE NOTABLE THE SHORT-CHAIN FATTY ACID (SCFA) EXCRETION. OBJECTIVES: ANALYZE THE INTERACTION BETWEEN MICROBIOTA, SCFAS, DIET, AND MS. METHODS: 16S, NUTRITIONAL QUESTIONNAIRES, AND SCFAS QUANTIFICATION HAVE BEEN RECOVERED FROM MS PATIENTS AND CONTROLS. RESULTS: OUR RESULTS REVEALED AN INCREMENT IN THE PHYLUM PROTEOBACTERIA, ESPECIALLY THE FAMILY ENTEROBACTERIACEAE, A LACK IN TOTAL SCFA EXCRETION, AND AN ALTERED PROFILE OF SCFAS IN A SPANISH COHORT OF MS PATIENTS. THESE ALTERATIONS ARE MORE EVIDENT IN PATIENTS WITH HIGHER DISABILITY. CONCLUSIONS: THE ABUNDANCE OF PROTEOBACTERIA AND ACETATE AND THE LOW EXCRETION OF TOTAL SCFAS, ESPECIALLY BUTYRATE, ARE COMMON CHARACTERISTICS OF MS PATIENTS, AND BESIDES, BOTH ARE ASSOCIATED WITH A WORSE PROGNOSIS OF THE DISEASE. 2022 5 2004 39 EPIGENETIC ASPECTS OF MULTIPLE SCLEROSIS AND FUTURE THERAPEUTIC OPTIONS. MULTIPLE SCLEROSIS (MS) IS A CHRONIC INFLAMMATORY AND NEURODEGENERATIVE DISEASE ACCOMPANIED BY DEMYELINATION OF NEURONS IN THE CENTRAL NERVOUS SYSTEM THAT MOSTLY AFFECTS YOUNG ADULTS, ESPECIALLY WOMEN. THIS DISEASE HAS TWO PHASES INCLUDING RELAPSING-REMITTING FORM (RR-MS) BY EPISODES OF RELAPSE AND PERIODS OF CLINICAL REMISSION AND SECONDARY-PROGRESSIVE FORM (SP-MS), WHICH CAUSES MORE DISABILITY. THE INHERITANCE PATTERN OF MS IS NOT EXACTLY IDENTIFIED AND THERE IS AN AGREEMENT THAT IT HAS A COMPLEX PATTERN WITH AN INTERPLAY AMONG ENVIRONMENTAL, GENETIC AND EPIGENETIC ALTERNATIONS. EPIGENETIC MECHANISMS THAT ARE IDENTIFIED FOR MS PATHOGENESIS ARE DNA METHYLATION, HISTONE MODIFICATION AND SOME MICRORNAS' ALTERNATIONS. SEVERAL CELLULAR PROCESSES INCLUDING APOPTOSIS, DIFFERENTIATION AND EVOLUTION CAN BE MODIFIED ALONG WITH EPIGENETIC CHANGES. SOME ALTERNATIONS ARE ASSOCIATED WITH EPIGENETIC MECHANISMS IN MS PATIENTS AND THESE CHANGES CAN BECOME KEY POINTS FOR MS THERAPY. THEREFORE, THE AIM OF THIS REVIEW WAS TO DISCUSS EPIGENETIC MECHANISMS THAT ARE ASSOCIATED WITH MS PATHOGENESIS AND FUTURE THERAPEUTIC APPROACHES. 2021 6 950 33 CHRONIC MILD STRESS EXACERBATES SEVERITY OF EXPERIMENTAL AUTOIMMUNE ENCEPHALOMYELITIS IN ASSOCIATION WITH ALTERED NON-CODING RNA AND METABOLIC BIOMARKERS. THE CAUSAL FACTORS DETERMINING THE ONSET AND SEVERITY OF MULTIPLE SCLEROSIS (MS) ARE NOT WELL UNDERSTOOD. HERE, WE INVESTIGATED THE INFLUENCE OF CHRONIC STRESS ON CLINICAL SYMPTOMS, METABOLIC AND EPIGENETIC MANIFESTATIONS OF EXPERIMENTAL AUTOIMMUNE ENCEPHALOMYELITIS (EAE), A COMMON ANIMAL MODEL OF MS. LEWIS RATS WERE IMMUNIZED FOR MONOPHASIC EAE WITH MBP(69-88) AND WERE EXPOSED TO CHRONIC STRESS FOR 37DAYS STARTING 7DAYS PRIOR TO IMMUNIZATION. THE EXPOSURE TO STRESS ACCELERATED AND EXACERBATED THE CLINICAL SYMPTOMS OF EAE. BOTH STRESS AND EAE ALSO DISRUPTED METABOLIC STATUS AS INDICATED BY TRACE ELEMENTAL ANALYSIS IN BODY HAIR. STRESS PARTICULARLY EXACERBATED CHLORINE DEPOSITION IN EAE ANIMALS. MOREOVER, DEEP SEQUENCING REVEALED A CONSIDERABLE IMPACT OF STRESS ON MICRORNA EXPRESSION IN EAE. EAE BY ITSELF UPREGULATED MICRORNA EXPRESSION IN LUMBAR SPINAL CORD, INCLUDING MIR-21, MIR-142-3P, MIR-142-5P, MIR-146A, AND MIR-155. STRESS IN EAE FURTHER UP-REGULATED MIR-16, MIR-146A AND MIR-155 LEVELS. THE LATTER TWO MICRORNAS ARE RECOGNIZED BIOMARKERS OF HUMAN MS. THUS, STRESS MAY SYNERGISTICALLY EXACERBATE SEVERITY OF EAE BY ALTERING EPIGENETIC REGULATORY PATHWAYS. THE FINDINGS SUGGEST THAT STRESS MAY REPRESENT A SIGNIFICANT RISK FACTOR FOR SYMPTOMATIC DETERIORATION IN MS. STRESS-RELATED METABOLIC AND MICRORNA SIGNATURES SUPPORT THEIR VALUE AS BIOMARKERS FOR PREDICTING THE RISK AND SEVERITY OF MS. 2017 7 1611 45 DNA METHYLATION: A NEW PLAYER IN MULTIPLE SCLEROSIS. MULTIPLE SCLEROSIS (MS) IS A NEUROLOGICAL AND CHRONIC INFLAMMATORY DISEASE THAT IS MEDIATED BY DEMYELINATION AND AXONAL DEGENERATION IN THE CENTRAL NERVOUS SYSTEM (CNS). STUDIES HAVE SHOWN THAT IMMUNE SYSTEM COMPONENTS SUCH AS CD4+, CD8+, CD44+ T CELLS, B LYMPHATIC CELLS, AND INFLAMMATORY CYTOKINES PLAY A CRITICAL ROLE IN INFLAMMATORY PROCESSES AND MYELIN DAMAGE ASSOCIATED WITH MS. NEVERTHELESS, THE PATHOGENESIS OF MS REMAINS POORLY DEFINED. DNA METHYLATION, A SIGNIFICANT EPIGENETIC MODIFICATION, IS REPORTED TO BE EXTENSIVELY INVOLVED IN MS PATHOGENESIS THROUGH THE REGULATION OF GENE EXPRESSION. THIS REVIEW FOCUSES ON DNA METHYLATION INVOLVED IN MS PATHOGENESIS. EVIDENCE SHOWED THE HYPERMETHYLATION OF HUMAN LEUKOCYTE ANTIGEN-DRB1 (HLA-DRB1) IN CD4+ T CELLS, THE GENOME-WIDE DNA METHYLATION IN CD8+ T CELLS, THE HYPERMETHYLATION OF INTERLEUKIN-4 (IL-4)/FORKHEAD WINGED HELIX TRANSCRIPTION FACTOR 3 (FOXP3), AND THE DEMETHYLATION OF INTERFERON-GAMMA (IFN-GAMMA)/IL-17A IN CD44+ ENCEPHALITOGENIC T CELLS. STUDIES ALSO SHOWED THE HYPERMETHYLATION OF SH2-CONTAINING PROTEIN TYROSINE PHOSPHATASE-1 (SHP-1) IN PERIPHERAL BLOOD MONONUCLEAR CELLS (PBMCS) AND METHYLATED CHANGES OF GENES REGULATING OLIGODENDROCYTE AND NEURONAL FUNCTION IN NORMAL-APPEARING WHITE MATTER. CLARIFYING THE MECHANISM OF ABERRANT METHYLATION ON MS MAY EXPLAIN PART OF THE PATHOLOGY AND WILL LEAD TO THE DEVELOPMENT OF A NEW THERAPEUTIC TARGET FOR THE TREATMENT OF MS IN THE FUTURE. 2017 8 3446 36 HYPERMETHYLATION OF MIR21 IN CD4+ T CELLS FROM PATIENTS WITH RELAPSING-REMITTING MULTIPLE SCLEROSIS ASSOCIATES WITH LOWER MIRNA-21 LEVELS AND CONCOMITANT UP-REGULATION OF ITS TARGET GENES. BACKGROUND: MULTIPLE SCLEROSIS (MS) IS A CHRONIC INFLAMMATORY DISEASE OF THE CENTRAL NERVOUS SYSTEM CAUSED BY GENETIC AND ENVIRONMENTAL FACTORS. DNA METHYLATION, AN EPIGENETIC MECHANISM THAT CONTROLS GENOME ACTIVITY, MAY PROVIDE A LINK BETWEEN GENETIC AND ENVIRONMENTAL RISK FACTORS. OBJECTIVE: WE SOUGHT TO IDENTIFY DNA METHYLATION CHANGES IN CD4+ T CELLS IN PATIENTS WITH RELAPSING-REMITTING (RR-MS) AND SECONDARY-PROGRESSIVE (SP-MS) DISEASE AND HEALTHY CONTROLS (HC). METHODS: WE PERFORMED DNA METHYLATION ANALYSIS IN CD4+ T CELLS FROM RR-MS, SP-MS, AND HC AND ASSOCIATED IDENTIFIED CHANGES WITH THE NEARBY RISK ALLELE, SMOKING, AGE, AND GENE EXPRESSION. RESULTS: WE OBSERVED SIGNIFICANT METHYLATION DIFFERENCES IN THE VMP1/MIR21 LOCUS, WITH RR-MS DISPLAYING HIGHER METHYLATION COMPARED TO SP-MS AND HC. VMP1/MIR21 METHYLATION DID NOT CORRELATE WITH A KNOWN MS RISK VARIANT IN VMP1 OR SMOKING BUT DISPLAYED A SIGNIFICANT NEGATIVE CORRELATION WITH AGE AND THE LEVELS OF MATURE MIR-21 IN CD4+ T CELLS. ACCORDINGLY, RR-MS DISPLAYED LOWER LEVELS OF MIR-21 COMPARED TO SP-MS, WHICH MIGHT REFLECT DIFFERENCES IN AGE BETWEEN THE GROUPS, AND HEALTHY INDIVIDUALS AND A SIGNIFICANT ENRICHMENT OF UP-REGULATED MIR-21 TARGET GENES. CONCLUSION: DISEASE-RELATED CHANGES IN EPIGENETIC MARKING OF MIR21 IN RR-MS LEAD TO DIFFERENCES IN MIR-21 EXPRESSION WITH A CONSEQUENCE ON MIR-21 TARGET GENES. 2018 9 2856 38 FROM METHYLATION TO MYELINATION: EPIGENOMIC AND TRANSCRIPTOMIC PROFILING OF CHRONIC INACTIVE DEMYELINATED MULTIPLE SCLEROSIS LESIONS. IN THE PROGRESSIVE PHASE OF MULTIPLE SCLEROSIS (MS), THE HAMPERED DIFFERENTIATION CAPACITY OF OLIGODENDROCYTE PRECURSOR CELLS (OPCS) EVENTUALLY RESULTS IN REMYELINATION FAILURE. WE HAVE PREVIOUSLY SHOWN THAT DNA METHYLATION OF ID2/ID4 IS HIGHLY INVOLVED IN OPC DIFFERENTIATION AND REMYELINATION. IN THIS STUDY, WE TOOK AN UNBIASED APPROACH BY DETERMINING GENOME-WIDE DNA METHYLATION PATTERNS WITHIN CHRONICALLY DEMYELINATED MS LESIONS AND INVESTIGATED HOW CERTAIN EPIGENETIC SIGNATURES RELATE TO OPC DIFFERENTIATION CAPACITY. WE COMPARED GENOME-WIDE DNA METHYLATION AND TRANSCRIPTIONAL PROFILES BETWEEN CHRONICALLY DEMYELINATED MS LESIONS AND MATCHED NORMAL-APPEARING WHITE MATTER (NAWM), MAKING USE OF POST-MORTEM BRAIN TISSUE (N = 9/GROUP). DNA METHYLATION DIFFERENCES THAT INVERSELY CORRELATED WITH MRNA EXPRESSION OF THEIR CORRESPONDING GENES WERE VALIDATED FOR THEIR CELL-TYPE SPECIFICITY IN LASER-CAPTURED OPCS USING PYROSEQUENCING. THE CRISPR-DCAS9-DNMT3A/TET1 SYSTEM WAS USED TO EPIGENETICALLY EDIT HUMAN-IPSC-DERIVED OLIGODENDROCYTES TO ASSESS THE EFFECT ON CELLULAR DIFFERENTIATION. OUR DATA SHOW HYPERMETHYLATION OF CPGS WITHIN GENES THAT CLUSTER IN GENE ONTOLOGIES RELATED TO MYELINATION AND AXON ENSHEATHMENT. CELL TYPE-SPECIFIC VALIDATION INDICATES A REGION-DEPENDENT HYPERMETHYLATION OF MBP, ENCODING FOR MYELIN BASIC PROTEIN, IN OPCS OBTAINED FROM WHITE MATTER LESIONS COMPARED TO NAWM-DERIVED OPCS. BY ALTERING THE DNA METHYLATION STATE OF SPECIFIC CPGS WITHIN THE PROMOTOR REGION OF MBP, USING EPIGENETIC EDITING, WE SHOW THAT CELLULAR DIFFERENTIATION AND MYELINATION CAN BE BIDIRECTIONALLY MANIPULATED USING THE CRISPR-DCAS9-DNMT3A/TET1 SYSTEM IN VITRO. OUR DATA INDICATE THAT OPCS WITHIN CHRONICALLY DEMYELINATED MS LESIONS ACQUIRE AN INHIBITORY PHENOTYPE, WHICH TRANSLATES INTO HYPERMETHYLATION OF CRUCIAL MYELINATION-RELATED GENES. ALTERING THE EPIGENETIC STATUS OF MBP CAN RESTORE THE DIFFERENTIATION CAPACITY OF OPCS AND POSSIBLY BOOST (RE)MYELINATION. 2023 10 2046 32 EPIGENETIC CLOCK INDICATES ACCELERATED AGING IN GLIAL CELLS OF PROGRESSIVE MULTIPLE SCLEROSIS PATIENTS. BACKGROUND: MULTIPLE SCLEROSIS (MS) IS A CHRONIC INFLAMMATORY NEURODEGENERATIVE DISEASE OF THE CENTRAL NERVOUS SYSTEM (CNS) CHARACTERIZED BY IRREVERSIBLE DISABILITY AT LATER PROGRESSIVE STAGES. A GROWING BODY OF EVIDENCE SUGGESTS THAT DISEASE PROGRESSION DEPENDS ON AGE AND INFLAMMATION WITHIN THE CNS. WE AIMED TO INVESTIGATE EPIGENETIC AGING IN BULK BRAIN TISSUE AND SORTED NUCLEI FROM MS PATIENTS USING DNA METHYLATION-BASED EPIGENETIC CLOCKS. METHODS: WE APPLIED HORVATH'S MULTI-TISSUE AND SHIREBY'S BRAIN-SPECIFIC CORTICAL CLOCK ON BULK BRAIN TISSUE (N = 46), SORTED NEURONAL (N = 54), AND GLIAL NUCLEI (N = 66) FROM POST-MORTEM BRAIN TISSUE OF PROGRESSIVE MS PATIENTS AND CONTROLS. RESULTS: WE FOUND A SIGNIFICANT INCREASE IN AGE ACCELERATION RESIDUALS, CORRESPONDING TO 3.6 YEARS, IN GLIAL CELLS OF MS PATIENTS COMPARED TO CONTROLS (P = 0.0024) USING THE CORTICAL CLOCK, WHICH HELD AFTER ADJUSTMENT FOR COVARIATES (P (ADJ) = 0.0263). THE 4.8-YEAR AGE ACCELERATION FOUND IN MS NEURONS (P = 0.0054) DID NOT WITHSTAND ADJUSTMENT FOR COVARIATES AND NO SIGNIFICANT DIFFERENCE IN AGE ACCELERATION RESIDUALS WAS OBSERVED IN BULK BRAIN TISSUE BETWEEN MS PATIENTS AND CONTROLS. CONCLUSION: WHILE THE FINDINGS WARRANT REPLICATION IN LARGER COHORTS, OUR STUDY SUGGESTS THAT GLIAL CELLS OF PROGRESSIVE MS PATIENTS EXHIBIT ACCELERATED BIOLOGICAL AGING. 2022 11 5426 44 REGULATION OF SIRTUIN EXPRESSION IN AUTOIMMUNE NEUROINFLAMMATION: INDUCTION OF SIRT1 IN OLIGODENDROCYTE PROGENITOR CELLS. IN MULTIPLE SCLEROSIS (MS) REGENERATION OF OLIGODENDROCYTES FOLLOWING INFLAMMATORY DEMYELINATION IS LIMITED BY THE COMPROMISED ABILITY OF PROGENITORS TO REPOPULATE LESIONED AREAS AND TRANSITION TO FUNCTIONALLY COMPETENT OLIGODENDROCYTES. REGARDING UNDERLYING MECHANISMS, THE INVOLVEMENT OF EPIGENETIC PROCESSES HAS BEEN SUGGESTED, E.G. THE CONTRIBUTION OF HISTONE DEACETYLASES (HDAC) KNOWN TO REGULATE OLIGODENDROCYTE PROGENITOR CELL (OPC) DIFFERENTIATION. HOWEVER, THEIR PRECISE EXPRESSION PATTERNS, PARTICULAR OF REDOX-SENSITIVE NAD(+) HDACS, REMAINS LARGELY UNKNOWN. IN THIS STUDY, WE DETERMINED THE EXPRESSION AND ACTIVITY OF SIRTUINS, MEMBERS OF THE HDAC CLASS III FAMILY WITH A SPECIFIC FOCUS ON SIRT1, PREVIOUSLY ASSOCIATED WITH NEURODEGENERATIVE, INFLAMMATORY AND DEMYELINATING DISORDERS OF THE CENTRAL NERVOUS SYSTEM (CNS). BY INVESTIGATING MOUSE EXPERIMENTAL AUTOIMMUNE ENCEPHALOMYELITIS (EAE), A MODEL FOR MS, WE FOUND THAT TRANSCRIPTION OF SIRT1, SIRT2 AND SIRT6 WAS SIGNIFICANTLY INCREASED IN THE CNS DURING CHRONIC DISEASE STAGES. WE CONFIRMED THIS FINDING FOR SIRT1 PROTEIN EXPRESSION AND WERE ABLE TO LOCALIZE UPREGULATED SIRT1 IN NUCLEI OF NG2(+) OR PDGFRALPHA(+) OPCS IN DEMYELINATED BRAIN LESIONS. IN CULTURED MOUSE A2B5(+) OPCS BLOCKADE OF SIRT1 ACTIVITY BY THE SMALL MOLECULE COMPOUND EX527 ENHANCED MITOTIC ACTIVITY BUT DID NOT AFFECT THE CAPACITY TO DIFFERENTIATE. A SIMILAR PATTERN WAS DETECTABLE IN OPCS DERIVED FROM SIRT1-DEFICIENT ANIMALS. TAKEN TOGETHER, OUR DATA SUGGEST THAT SIRT1 INHIBITION MAY HELP TO EXPAND THE ENDOGENOUS POOL OF OPCS WITHOUT AFFECTING THEIR DIFFERENTIATION. 2019 12 4439 33 MOLECULAR GENETIC AND EPIGENETIC BASIS OF MULTIPLE SCLEROSIS. MULTIPLE SCLEROSIS (MS) IS A CHRONIC IMMUNE-MEDIATED DISEASE OF SPINAL CORD AND BRAIN. THE INITIAL EVENT IN MS OCCURS WHEN ACTIVATED CD4(+) T CELLS IN PERIPHERY EXACERBATES IMMUNE RESPONSES BY STIMULATING IMMUNE CELLS SUCH AS B CELLS, CD8(+) CELLS, MAST CELLS, GRANULOCYTES AND MONOCYTES. THESE PROINFLAMMATORY CELLS PASS BLOOD BRAIN BARRIER BY SECRETING PROINFLAMMATORY CYTOKINES INCLUDING TNF-ALPHA AND INF-(GAMMA) WHICH ACTIVATE ADHESION FACTORS. APCS (ANTIGEN-PRESENTING CELLS) REACTIVATE CD4(+) T CELLS AFTER INFILTRATING THE CNS AND CD4(+) T CELLS PRODUCE CYTOKINES AND CHEMOKINES. THESE PROINFLAMMATORY CYTOKINES AGGRAVATE INFLAMMATION BY INDUCING MYELIN PHAGOCYTOSIS THROUGH MICROGLIA AND ASTROCYTES ACTIVATION. MS IS BELIEVED TO HAVE A MULTIFACTORIAL ORIGIN THAT INCLUDES A COMBINATION OF MULTIPLE GENETIC, ENVIRONMENTAL AND STOCHASTIC FACTORS. ALTHOUGH THE EXACT COMPONENT OF MS RISKS THAT CAN BE EXPLAINED BY THESE FACTORS IS DIFFICULT TO DETERMINE, ESTIMATES BASED ON GENETIC AND EPIDEMIOLOGICAL STUDIES SUGGEST THAT UP TO 60-70 % OF THE TOTAL RISK OF MS MAY BE CONTRIBUTE TO GENETIC FACTORS. IN CONTINUE, FIRSTLY WE PROVIDE AN OVERVIEW OF THE CURRENT UNDERSTANDING OF EPIGENETIC MECHANISMS, AND SO PRESENT EVIDENCE OF HOW THE EPIGENETIC MODIFICATIONS CONTRIBUTE TO INCREASED SUSCEPTIBILITY OF MS. WE ALSO EXPLAIN HOW SPECIFIED EPIGENETIC MODIFICATIONS MAY INFLUENCE THE PATHOPHYSIOLOGY AND KEY ASPECTS OF DISEASE IN MS (DEMYELINATION, REMYELINATION, INFLAMMATION, AND NEURODEGENERATION). FINALLY, WE TEND TO DISCUSS HOW ENVIRONMENTAL FACTORS AND EPIGENETIC MECHANISMS MAY INTERACT TO HAVE AN EFFECT ON MS RISK AND CLINICAL OUTCOME AND RECOMMEND NEW THERAPEUTIC INTERVENTIONS THAT MIGHT MODULATE PATIENTS' EPIGENETIC PROFILES. 2017 13 1994 39 EPIGENETIC AND GENE EXPRESSION ALTERATIONS OF FOXP3 IN THE T CELLS OF EAE MOUSE MODEL OF MULTIPLE SCLEROSIS. MULTIPLE SCLEROSIS (MS) IS A CHRONIC AUTOIMMUNE DISEASE WITH DEMYELINATION AND NEURODEGENERATION OF THE CENTRAL NERVOUS SYSTEM. IT HAS BEEN SHOWN THAT THE REGULATORY T (TREG) CELLS ARE RESPONSIBLE FOR MAINTAINING TOLERANCE TO SELF-ANTIGENS AND CAN SUPPRESS THE AUTOIMMUNE PROCESS IN SEVERAL ANIMAL MODELS SUCH AS EXPERIMENTAL AUTOIMMUNE ENCEPHALOMYELITIS (EAE), A MOUSE MODEL OF MS. RECENT BASIC STUDIES HAVE DEMONSTRATED THAT FORKHEAD BOX P (FOXP3) AND BTB DOMAIN AND CNC HOMOLOG 2 (BACH2) ARE THE MASTER TRANSCRIPTION FACTORS OF THESE CELLS PLAYING A PIVOTAL ROLE IN THE POLARIZATION OF NAIVE T CELLS INTO TREG CELLS. IN THE CURRENT STUDY, THE EXPRESSION OF FOXP3 AND BACH2 GENES AND FOXP3 PROMOTER METHYLATION WERE EVALUATED IN T CELLS OF THE EAE-INDUCED MICE. THE RESULTS OF THIS STUDY SHOWED A PROMINENT AND SIGNIFICANT HYPERMETHYLATION OF THE FOXP3 GENE PROMOTER IN THE EAE-INDUCED MICE COMPARED TO THE SHAM AND CONTROL GROUPS. THE EXPRESSION OF FOXP3 AND BACH2 GENES WAS SIGNIFICANTLY DECREASED IN THE EAE GROUP IN COMPARISON WITH THE SHAM AND CONTROL GROUPS. THIS STUDY SUGGESTS THAT THE EPIGENETIC MODIFICATION OF FOXP3 GENE IS INVOLVED IN THE PATHOGENESIS OF EAE AND THIS COULD BE IMPORTANT IN THERAPY IN AN APPROPRIATE AND LOGICAL STATEMENT. 2017 14 2546 44 EPIGENETICS IN MULTIPLE SCLEROSIS: MOLECULAR MECHANISMS AND DIETARY INTERVENTION. INTRODUCTION: MULTIPLE SCLEROSIS (MS) IS A CHRONIC, INFLAMMATORY, NEURODEGENERATIVE DEMYELINATING DISEASE OF THE CENTRAL NERVOUS SYSTEM (CNS). UNFORTUNATELY, MS CAUSES IMPORTANT DISABILITY IN YOUNG ADULTS AND ITS PREVALENCE IS INCREASING. WHILE THE ETIOLOGY OF MS ETIOLOGY IS NOT COMPLETELY UNDERSTOOD, IT SEEMS TO BE A MULTIFACTORIAL ENTITY THAT IS INFLUENCED BY BOTH GENETIC AND EPIGENETIC MODIFICATIONS. EPIGENETIC MECHANISMS ADD OR REMOVE DIFFERENT CHEMICAL GROUPS FOR THE ACTIVATION OR INHIBITION OF GENE EXPRESSION TO BLOCK THE PRODUCTION OF PROINFLAMMATORY PROTEINS. IT IS TRULY IMPORTANT TO IDENTIFY THE FACTORS THAT CAN TRIGGER EPIGENETIC CHANGES IN MS TO COMPLEMENT THE THERAPEUTIC APPROACH, PREVENT DISABILITY AND IMPROVE PATIENTS QUALITY OF LIFE. HERE, WE HAVE CONDUCTED A REVIEW OF EXTERNAL FACTORS THAT INFLUENCE IN MS AND THEIR EPIGENETIC MECHANISMS. FOR EXAMPLE, HYPOMETHYLATION CAN PROMOTE CHANGES IN THE MYELIN AND SUBSEQUENT AUTOIMMUNE REACTIONS. THERAPEUTIC TOOLS CAN BE USED, INCLUDING THE HISTONE DEACETYLASE INHIBITOR TRICHOSTATIN A, WHICH AMELIORATES DEMYELINATING DISEASES IN RODENTS. HOWEVER, DRUGS ARE NOT ONLY THE THERAPEUTIC OPTION: RECENT STUDIES HAVE ALSO EVALUATED THE THERAPEUTIC POTENTIAL OF SEVERAL BIOACTIVE DIETARY COMPONENTS IN NEURODEGENERATION AND AXONAL DYSFUNCTION. NUMEROUS FOOD-DERIVED MOLECULES EXERT IMPORTANT METABOLIC ACTIONS. THESE MOLECULES INCLUDE PLANT POLYPHENOLS SUCH AS CATECHINS AND ISOFLAVONES, OMEGA-3 AND OMEGA-6 POLYUNSATURATED FATTY ACIDS, SHORT-CHAIN FATTY ACIDS, SULFUR-CONTAINING COMPOUNDS SUCH AS DALLY SULFIDE AND OTHER COMPOUNDS. ANTIOXIDANT AND ANTI-INFLAMMATORY COMPONENTS IN THE DIET INVOLVE TRANSCRIPTION FACTORS AS WELL. HOWEVER, MANY EXTERNAL FACTORS HAVE SHOWN TO INFLUENCE MS, ALTHOUGH NO SPECIFIC EPIGENETIC MECHANISMS ARE KNOWN. CONCLUSION: IN THIS REVIEW, WE GATHER BOTH ESTABLISHED AND NEW EVIDENCES ABOUT THE GENETIC, EPIGENETIC AND ENVIRONMENTAL FACTORS INFLUENCING MS AND THE DIETARY COMPONENTS THAT COULD MODULATE MS RELAPSE AND PROGRESSION. 2018 15 1526 37 DNA METHYLATION CHANGES IN GLIAL CELLS OF THE NORMAL-APPEARING WHITE MATTER IN MULTIPLE SCLEROSIS PATIENTS. MULTIPLE SCLEROSIS (MS), THE LEADING CAUSE OF NON-TRAUMATIC NEUROLOGICAL DISABILITY IN YOUNG ADULTS, IS A CHRONIC INFLAMMATORY AND NEURODEGENERATIVE DISEASE OF THE CENTRAL NERVOUS SYSTEM (CNS). DUE TO THE POOR ACCESSIBILITY TO THE TARGET ORGAN, CNS-CONFINED PROCESSES UNDERPINNING THE LATER PROGRESSIVE FORM OF MS REMAIN ELUSIVE THEREBY LIMITING TREATMENT OPTIONS. WE AIMED TO EXAMINE DNA METHYLATION, A STABLE EPIGENETIC MARK OF GENOME ACTIVITY, IN GLIAL CELLS TO CAPTURE RELEVANT MOLECULAR CHANGES UNDERLYING MS NEUROPATHOLOGY. WE PROFILED DNA METHYLATION IN NUCLEI OF NON-NEURONAL CELLS, ISOLATED FROM 38 POST-MORTEM NORMAL-APPEARING WHITE MATTER (NAWM) SPECIMENS OF MS PATIENTS (N = 8) IN COMPARISON TO WHITE MATTER OF CONTROL INDIVIDUALS (N = 14), USING INFINIUM METHYLATIONEPIC BEADCHIP. WE IDENTIFIED 1,226 SIGNIFICANT (GENOME-WIDE ADJUSTED P-VALUE < 0.05) DIFFERENTIALLY METHYLATED POSITIONS (DMPS) BETWEEN MS PATIENTS AND CONTROLS. FUNCTIONAL ANNOTATION OF THE ALTERED DMP-GENES UNCOVERED ALTERATIONS OF PROCESSES RELATED TO CELLULAR MOTILITY, CYTOSKELETON DYNAMICS, METABOLIC PROCESSES, SYNAPTIC SUPPORT, NEUROINFLAMMATION AND SIGNALING, SUCH AS WNT AND TGF-BETA PATHWAYS. A FRACTION OF THE AFFECTED GENES DISPLAYED TRANSCRIPTIONAL DIFFERENCES IN THE BRAIN OF MS PATIENTS, AS REPORTED BY PUBLICALLY AVAILABLE TRANSCRIPTOMIC DATA. CELL TYPE-RESTRICTED ANNOTATION OF DMP-GENES ATTRIBUTED ALTERATIONS OF CYTOSKELETON REARRANGEMENT AND EXTRACELLULAR MATRIX REMODELLING TO ALL GLIAL CELL TYPES, WHILE SOME PROCESSES, INCLUDING ION TRANSPORT, WNT/TGF-BETA SIGNALING AND IMMUNE PROCESSES WERE MORE SPECIFICALLY LINKED TO OLIGODENDROCYTES, ASTROCYTES AND MICROGLIAL CELLS, RESPECTIVELY. OUR FINDINGS STRONGLY SUGGEST THAT NAWM GLIAL CELLS ARE HIGHLY ALTERED, EVEN IN THE ABSENCE OF LESIONAL INSULT, COLLECTIVELY EXHIBITING A MULTICELLULAR REACTION IN RESPONSE TO DIFFUSE INFLAMMATION. 2022 16 4536 36 MULTIPLE SCLEROSIS - RISK FACTORS. MULTIPLE SCLEROSIS (MS) IS A CHRONIC AUTOIMMUNOLOGICAL CONDITION OF THE CENTRAL NERVOUS SYSTEM (CNS) AFFECTING MAINLY YOUNG ADULT INDIVIDUALS. THE PREVALENCE RANGES APPROXIMATELY BETWEEN 50 AND 300 PER 100000 INDIVIDUALS. IT IS CHARACTERIZED BY AN INFLAMMATORY PROCESS, DEMYELINATION AND AXONAL LOSS. IMMUNOLOGICAL MECHANISMS RESULTING IN THE DAMAGE TO THE MYELIN SHEATH EFFECTING THEN IN IMPAIRED NERVE IMPULSE CONDUCTION HAVE THE KEY ROLE IN MS PATHOGENESIS. THE ROLE OF INFLAMMATORY FACTORS HAS ALSO BEEN PROVED. HOWEVER, IT HAS NOT BEEN EXPLICITLY SHOWN WHETHER SUCH AN INFLAMMATORY PROCESS IS THE TRIGGERING FACTOR OR SECONDARY TO A YET UNKNOWN INFECTIOUS FACTOR OR A DEGENERATIVE PROCESS OF THE CNS. THEREFORE, RECOGNITION OF THE EPIGENETIC RISK FACTORS, SUCH AS: GEOGRAPHICAL LATITUDE, VITAMIN D LEVEL, HYGIENE HYPOTHESIS, EPSTEIN-BARR VIRUS (EBV) INFECTION AND OTHERS MAY CONTRIBUTE TO BETTER UNDERSTANDING OF THE MECHANISM UNDERLYING MULTIPLE SCLEROSIS. ADDITIONALLY, THEY MAY PROVIDE GUIDELINES FOR MORE EFFICIENT THERAPIES AND BETTER PREVENTION OF THE DISEASE. AIM OF THIS REVIEW IS TO PRESENT MOST CURRENT DATA ON MULTIPLE SCLEROSIS RISK FACTORS, CONSIDERING THOSE LESS KNOWN. 2020 17 6531 36 TRANSCRIPTIONAL REGULATION OF BRAIN-DERIVED NEUROTROPHIC FACTOR (BDNF) BY METHYL CPG BINDING PROTEIN 2 (MECP2): A NOVEL MECHANISM FOR RE-MYELINATION AND/OR MYELIN REPAIR INVOLVED IN THE TREATMENT OF MULTIPLE SCLEROSIS (MS). MULTIPLE SCLEROSIS (MS) IS A CHRONIC PROGRESSIVE, NEUROLOGICAL DISEASE CHARACTERIZED BY THE TARGETED IMMUNE SYSTEM-MEDIATED DESTRUCTION OF CENTRAL NERVOUS SYSTEM (CNS) MYELIN. AUTOREACTIVE CD4+ T HELPER CELLS HAVE A KEY ROLE IN ORCHESTRATING MS-INDUCED MYELIN DAMAGE. ONCE ACTIVATED, CIRCULATING TH1-CELLS SECRETE A VARIETY OF INFLAMMATORY CYTOKINES THAT FOSTER THE BREAKDOWN OF BLOOD-BRAIN BARRIER (BBB) EVENTUALLY INFILTRATING INTO THE CNS. INSIDE THE CNS, THEY BECOME REACTIVATED UPON EXPOSURE TO THE MYELIN STRUCTURAL PROTEINS AND CONTINUE TO PRODUCE INFLAMMATORY CYTOKINES SUCH AS TUMOR NECROSIS FACTOR ALPHA (TNFALPHA) THAT LEADS TO DIRECT ACTIVATION OF ANTIBODIES AND MACROPHAGES THAT ARE INVOLVED IN THE PHAGOCYTOSIS OF MYELIN. PROLIFERATING OLIGODENDROCYTE PRECURSORS (OPS) MIGRATING TO THE LESION SITES ARE CAPABLE OF ACUTE REMYELINATION BUT UNABLE TO COMPLETELY REPAIR OR RESTORE THE IMMUNE SYSTEM-MEDIATED MYELIN DAMAGE. THIS RESULTS IN VARIOUS PERMANENT CLINICAL NEUROLOGICAL DISABILITIES SUCH AS COGNITIVE DYSFUNCTION, FATIGUE, BOWEL/BLADDER ABNORMALITIES, AND NEUROPATHIC PAIN. AT PRESENT, THERE IS NO CURE FOR MS. RECENT REMYELINATION AND/OR MYELIN REPAIR STRATEGIES HAVE FOCUSED ON THE ROLE OF THE NEUROTROPHIN BRAIN-DERIVED NEUROTROPHIC FACTOR (BDNF) AND ITS UPSTREAM TRANSCRIPTIONAL REPRESSOR METHYL CPG BINDING PROTEIN (MECP2). RESEARCH IN THE FIELD OF EPIGENETIC THERAPEUTICS INVOLVING HISTONE DEACETYLASE (HDAC) INHIBITORS AND LYSINE ACETYL TRANSFERASE (KAT) INHIBITORS IS BEING EXPLORED TO REPRESS THE DETRIMENTAL EFFECTS OF MECP2. THIS REVIEW WILL ADDRESS THE ROLE OF MECP2 AND BDNF IN REMYELINATION AND/OR MYELIN REPAIR AND THE POTENTIAL OF HDAC AND KAT INHIBITORS AS NOVEL THERAPEUTIC INTERVENTIONS FOR MS. 2016 18 3069 41 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. 2022 19 3135 38 GLOBAL DNA METHYLATION AND HYDROXYMETHYLATION LEVELS IN PBMCS ARE ALTERED IN RRMS PATIENTS TREATED WITH IFN-BETA AND GA-A PRELIMINARY STUDY. MULTIPLE SCLEROSIS (MS) IS A CHRONIC DISEASE AFFECTING THE CENTRAL NERVOUS SYSTEM (CNS) DUE TO AN AUTOIMMUNE ATTACK ON AXONAL MYELIN SHEATHS. EPIGENETICS IS AN OPEN RESEARCH TOPIC ON MS, WHICH HAS BEEN INVESTIGATED IN SEARCH OF BIOMARKERS AND TREATMENT TARGETS FOR THIS HETEROGENEOUS DISEASE. IN THIS STUDY, WE QUANTIFIED GLOBAL LEVELS OF EPIGENETIC MARKS USING AN ELISA-LIKE APPROACH IN PERIPHERAL BLOOD MONONUCLEAR CELLS (PBMCS) FROM 52 PATIENTS WITH MS, TREATED WITH INTERFERON BETA (IFN-BETA) AND GLATIRAMER ACETATE (GA) OR UNTREATED, AND 30 HEALTHY CONTROLS. WE PERFORMED MEDIA COMPARISONS AND CORRELATION ANALYSES OF THESE EPIGENETIC MARKERS WITH CLINICAL VARIABLES IN SUBGROUPS OF PATIENTS AND CONTROLS. WE OBSERVED THAT DNA METHYLATION (5-MC) DECREASED IN TREATED PATIENTS COMPARED WITH UNTREATED AND HEALTHY CONTROLS. MOREOVER, 5-MC AND HYDROXYMETHYLATION (5-HMC) CORRELATED WITH CLINICAL VARIABLES. IN CONTRAST, HISTONE H3 AND H4 ACETYLATION DID NOT CORRELATE WITH THE DISEASE VARIABLES CONSIDERED. GLOBALLY QUANTIFIED EPIGENETIC DNA MARKS 5-MC AND 5-HMC CORRELATE WITH DISEASE AND WERE ALTERED WITH TREATMENT. HOWEVER, TO DATE, NO BIOMARKER HAS BEEN IDENTIFIED THAT CAN PREDICT THE POTENTIAL RESPONSE TO THERAPY BEFORE TREATMENT INITIATION. 2023 20 6907 37 [THE ROLE OF THE CIRCULAR RNAS IN MULTIPLE SCLEROSIS AND OTHER NEUROIMMUNE DISORDERS]. IN RECENT YEARS NON-CODING RNAS HAVE RECEIVED INCREASING ATTENTION AS AN IMPORTANT EPIGENETIC MECHANISM, WITH PARTICULAR ROLE OF MICRO RNAS. AS THE REGULATION OF MIRNA EXPRESSION IS HIGHLY DYNAMIC AND COMPLEX, GROWING EVIDENCE SUGGESTS THE EXISTENCE OF ANOTHER HIGHER LEVEL OF REGULATORY MECHANISM INVOLVED IN MIRNA ACTIVITY - CIRCULAR RNAS (CIRCRNAS). CIRCRNAS REPRESENT NOVEL, UNIQUE CLASS OF ENDOGENOUS NCRNAS CONTROLLING THE EXPRESSION AND FUNCTION OF MIRNA. THEY ARE CALLED NATURAL MIRNA "SPONGES". ACCUMULATING EVIDENCE REVEALS CIRCRNAS ROLE IN PHYSIOLOGICAL AND PATHOLOGICAL PROCESSES INCLUDING CNS AND IMMUNE REGULATION. PREVIOUS STUDIES IMPLICATED MIRNAS IN REGULATION OF AUTOIMMUNE DEMYELINATION IN MS. MULTIPLE SCLEROSIS IS A CHRONIC NEUROLOGICAL INFLAMMATORY DEMYELINATING DISORDER OF THE CENTRAL NERVOUS SYSTEM. WHILE THE ETIOLOGY OF MS IS STILL NOT FULLY UNDERSTOOD, ACCUMULATING EVIDENCE SUGGESTS THAT IT IS A MULTIFACTORIAL ENTITY WITH SIGNIFICANT INVOLVEMENT OF AUTOIMMUNE PROCESSES. 2022