1 5408 129 REGULATION AND SIGNALING OF THE GPR17 RECEPTOR IN OLIGODENDROGLIAL CELLS. REMYELINATION, NAMELY, THE FORMATION OF NEW MYELIN SHEATHS AROUND DENUDED AXONS, COUNTERACTS AXONAL DEGENERATION AND RESTORES NEURONAL FUNCTION. CONSIDERABLE ADVANCES HAVE BEEN MADE IN UNDERSTANDING THIS REGENERATIVE PROCESS THAT OFTEN FAILS IN DISEASES LIKE MULTIPLE SCLEROSIS, LEAVING AXONS DEMYELINATED AND VULNERABLE TO DAMAGE, THUS CONTRIBUTING TO DISEASE PROGRESSION. THE IDENTIFICATION OF THE MEMBRANE RECEPTOR GPR17 ON A SUBSET OF OLIGODENDROCYTE PRECURSOR CELLS (OPCS), WHICH MEDIATE REMYELINATION IN THE ADULT CENTRAL NERVOUS SYSTEM (CNS), HAS LED TO A HUGE AMOUNT OF EVIDENCE THAT VALIDATED THIS RECEPTOR AS A NEW ATTRACTIVE TARGET FOR REMYELINATING THERAPIES. HERE, WE SUMMARIZE THE ROLE OF GPR17 IN OPC FUNCTION, MYELINATION AND REMYELINATION, DESCRIBING ITS ATYPICAL PHARMACOLOGY, ITS DOWNSTREAM SIGNALING, AND THE GENETIC AND EPIGENETIC FACTORS MODULATING ITS ACTIVITY. WE ALSO HIGHLIGHT CRUCIAL INSIGHTS INTO GPR17 PATHOPHYSIOLOGY COMING FROM THE DEMONSTRATION THAT OLIGODENDROCYTE INJURY, ASSOCIATED WITH INFLAMMATION IN CHRONIC NEURODEGENERATIVE CONDITIONS, IS INVARIABLY CHARACTERIZED BY ABNORMAL AND PERSISTENT GPR17 UPREGULATION, WHICH, IN TURN, IS ACCOMPANIED BY A BLOCK OF OPCS AT IMMATURE PREMYELINATING STAGES. FINALLY, WE DISCUSS THE CURRENT LITERATURE IN LIGHT OF THE POTENTIAL EXPLOITMENT OF GPR17 AS A THERAPEUTIC TARGET TO PROMOTE REMYELINATION. 2020 2 2882 47 G-PROTEIN-COUPLED RECEPTOR GPR17 REGULATES OLIGODENDROCYTE DIFFERENTIATION IN RESPONSE TO LYSOLECITHIN-INDUCED DEMYELINATION. OLIGODENDROCYTES ARE THE MYELIN-PRODUCING CELLS OF THE CENTRAL NERVOUS SYSTEM (CNS). A VARIETY OF BRAIN DISORDERS FROM "CLASSICAL" DEMYELINATING DISEASES, SUCH AS MULTIPLE SCLEROSIS, STROKE, SCHIZOPHRENIA, DEPRESSION, DOWN SYNDROME AND AUTISM, ARE SHOWN MYELINATION DEFECTS. OLIGODENDROCYTE MYELINATION IS REGULATED BY A COMPLEX INTERPLAY OF INTRINSIC, EPIGENETIC AND EXTRINSIC FACTORS. GPR17 (G PROTEIN-COUPLED RECEPTOR 17) IS A G PROTEIN-COUPLED RECEPTOR, AND HAS BEEN IDENTIFIED TO BE A REGULATOR FOR OLIGODENDROCYTE DEVELOPMENT. HERE, WE DEMONSTRATE THAT THE ABSENCE OF GPR17 ENHANCES REMYELINATION IN VIVO WITH A TOXIN-INDUCED MODEL WHEREBY FOCAL DEMYELINATED LESIONS ARE GENERATED IN SPINAL CORD WHITE MATTER OF ADULT MICE BY LOCALIZED INJECTION OF LPC(L-A-LYSOPHOSPHATIDYLCHOLINE). THE INCREASED EXPRESSION OF THE ACTIVATED FORM OF ERK1/2 (PHOSPHO-ERK1/2) IN LESION AREAS SUGGESTED THE POTENTIAL ROLE OF ERK1/2 ACTIVITY ON THE GPR17-DEPENDENT MODULATION OF MYELINATION. THE ABSENCE OF GPR17 ENHANCES REMYELINATION IS CORRELATE WITH THE ACTIVATED ERK1/2 (PHOSPHO-ERK1/2).BEING A MEMBRANE RECEPTOR, GPR17 REPRESENTS AN IDEAL DRUGGABLE TARGET TO BE EXPLOITED FOR INNOVATIVE REGENERATIVE APPROACHES TO ACUTE AND CHRONIC CNS DISEASES. 2018 3 80 44 A NEW ROLE FOR THE P2Y-LIKE GPR17 RECEPTOR IN THE MODULATION OF MULTIPOTENCY OF OLIGODENDROCYTE PRECURSOR CELLS IN VITRO. OLIGODENDROCYTE PRECURSOR CELLS (OPCS, ALSO CALLED NG2 CELLS) ARE SCATTERED THROUGHOUT BRAIN PARENCHYMA, WHERE THEY FUNCTION AS A RESERVOIR TO REPLACE LOST OR DAMAGED OLIGODENDROCYTES, THE MYELIN-FORMING CELLS. THE HYPOTHESIS THAT, UNDER SOME CIRCUMSTANCES, OPCS CAN ACTUALLY BEHAVE AS MULTIPOTENT CELLS, THUS GENERATING ASTROCYTES AND NEURONS AS WELL, HAS ARISEN FROM SOME IN VITRO AND IN VIVO EVIDENCE, BUT THE MOLECULAR PATHWAYS CONTROLLING THIS ALTERNATIVE FATE OF OPCS ARE NOT FULLY UNDERSTOOD. THEIR IDENTIFICATION WOULD OPEN NEW OPPORTUNITIES FOR NEURONAL REPLACE STRATEGIES, BY FOSTERING THE INTRINSIC ABILITY OF THE BRAIN TO REGENERATE. HERE, WE SHOW THAT THE ANTI-EPILEPTIC EPIGENETIC MODULATOR VALPROIC ACID (VPA) CAN PROMOTE THE GENERATION OF NEW NEURONS FROM NG2(+) OPCS UNDER NEUROGENIC PROTOCOLS IN VITRO, THROUGH THEIR INITIAL DE-DIFFERENTIATION TO A STEM CELL-LIKE PHENOTYPE THAT THEN EVOLVES TO "HYBRID" CELL POPULATION, SHOWING OPC MORPHOLOGY BUT EXPRESSING THE NEURONAL MARKER BETAIII-TUBULIN AND THE GPR17 RECEPTOR, A KEY DETERMINANT IN DRIVING OPC TRANSITION TOWARDS MYELINATING OLIGODENDROCYTES. UNDER THESE CONDITIONS, THE PHARMACOLOGICAL BLOCKADE OF THE P2Y-LIKE RECEPTOR GPR17 BY CANGRELOR, A DRUG RECENTLY APPROVED FOR HUMAN USE, PARTIALLY MIMICS THE EFFECTS MEDIATED BY VPA THUS ACCELERATING CELLS' NEUROGENIC CONVERSION. THESE DATA SHOW A CO-LOCALIZATION BETWEEN NEURONAL MARKERS AND GPR17 IN VITRO, AND SUGGEST THAT, BESIDES ITS INVOLVEMENT IN OLIGODENDROGENESIS, GPR17 CAN DRIVE THE FATE OF NEURAL PRECURSOR CELLS BY INSTRUCTING PRECURSORS TOWARDS THE NEURONAL LINEAGE. BEING A MEMBRANE RECEPTOR, GPR17 REPRESENTS AN IDEAL "DRUGGABLE" TARGET TO BE EXPLOITED FOR INNOVATIVE REGENERATIVE APPROACHES TO ACUTE AND CHRONIC BRAIN DISEASES. 2016 4 6531 41 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 5 4758 47 NOVEL TREATMENT STRATEGIES TARGETING MYELIN AND OLIGODENDROCYTE DYSFUNCTION IN SCHIZOPHRENIA. OLIGODENDROCYTES ARE THE GLIAL CELLS RESPONSIBLE FOR THE FORMATION OF THE MYELIN SHEATH AROUND AXONS. DURING NEURODEVELOPMENT, OLIGODENDROCYTES UNDERGO MATURATION AND DIFFERENTIATION, AND LATER REMYELINATION IN ADULTHOOD. ABNORMALITIES IN THESE PROCESSES HAVE BEEN ASSOCIATED WITH BEHAVIORAL AND COGNITIVE DYSFUNCTIONS AND THE DEVELOPMENT OF VARIOUS MENTAL ILLNESSES LIKE SCHIZOPHRENIA. SEVERAL STUDIES HAVE IMPLICATED OLIGODENDROCYTE DYSFUNCTION AND MYELIN ABNORMALITIES IN THE DISORDER, TOGETHER WITH ALTERED EXPRESSION OF MYELIN-RELATED GENES SUCH AS OLIG2, CNP, AND NRG1. HOWEVER, THE MOLECULAR MECHANISMS SUBJACENT OF THESE ALTERATIONS REMAIN ELUSIVE. SCHIZOPHRENIA IS A SEVERE, CHRONIC PSYCHIATRIC DISORDER AFFECTING MORE THAN 23 MILLION INDIVIDUALS WORLDWIDE AND ITS SYMPTOMS USUALLY APPEAR AT THE BEGINNING OF ADULTHOOD. CURRENTLY, THE MAJOR THERAPEUTIC STRATEGY FOR SCHIZOPHRENIA RELIES ON THE USE OF ANTIPSYCHOTICS. DESPITE THEIR WIDESPREAD USE, THE EFFECTS OF ANTIPSYCHOTICS ON GLIAL CELLS, ESPECIALLY OLIGODENDROCYTES, REMAIN UNCLEAR. THUS, IN THIS REVIEW WE HIGHLIGHT THE CURRENT KNOWLEDGE REGARDING OLIGODENDROCYTE DYSFUNCTION IN SCHIZOPHRENIA, COMPILING DATA FROM (EPI)GENETIC STUDIES AND UP-TO-DATE MODELS TO INVESTIGATE THE ROLE OF OLIGODENDROCYTES IN THE DISORDER. IN ADDITION, WE EXAMINED POTENTIAL TARGETS CURRENTLY INVESTIGATED FOR THE IMPROVEMENT OF SCHIZOPHRENIA SYMPTOMS. RESEARCH IN THIS AREA HAS BEEN INVESTIGATING POTENTIAL BENEFICIAL COMPOUNDS, INCLUDING THE D-AMINO ACIDS D-ASPARTATE AND D-SERINE, THAT ACT AS NMDA RECEPTOR AGONISTS, MODULATING THE GLUTAMATERGIC SIGNALING; THE ANTIOXIDANT N-ACETYLCYSTEINE, A PRECURSOR IN THE SYNTHESIS OF GLUTATHIONE, PROTECTING AGAINST THE REDOX IMBALANCE; AS WELL AS LITHIUM, AN INHIBITOR OF GLYCOGEN SYNTHASE KINASE 3BETA (GSK3BETA) SIGNALING, CONTRIBUTING TO OLIGODENDROCYTE SURVIVAL AND FUNCTIONING. IN CONCLUSION, THERE IS STRONG EVIDENCE LINKING OLIGODENDROCYTE DYSFUNCTION TO THE DEVELOPMENT OF SCHIZOPHRENIA. HENCE, A BETTER UNDERSTANDING OF OLIGODENDROCYTE DIFFERENTIATION, AS WELL AS THE EFFECTS OF ANTIPSYCHOTIC MEDICATION IN THESE CELLS, COULD HAVE POTENTIAL IMPLICATIONS FOR UNDERSTANDING THE DEVELOPMENT OF SCHIZOPHRENIA AND FINDING NEW TARGETS FOR DRUG DEVELOPMENT. 2020 6 6136 40 THE EPIGENETICS OF MULTIPLE SCLEROSIS AND OTHER RELATED DISORDERS. MULTIPLE SCLEROSIS (MS) IS A DEMYELINATING DISEASE CHARACTERIZED BY CHRONIC INFLAMMATION OF THE CENTRAL NERVOUS SYSTEM (CNS) GRAY AND WHITE MATTER. ALTHOUGH THE CAUSE OF MS IS UNKNOWN, IT IS WIDELY APPRECIATED THAT INNATE AND ADAPTIVE IMMUNE PROCESSES CONTRIBUTE TO ITS PATHOGENESIS. THESE INCLUDE MICROGLIA/MACROPHAGE ACTIVATION, PRO-INFLAMMATORY T-CELL (TH1) RESPONSES AND HUMORAL RESPONSES. ADDITIONALLY, THERE IS EVIDENCE INDICATING THAT MS HAS A NEURODEGENERATIVE COMPONENT SINCE NEURONAL AND AXONAL LOSS OCCURS EVEN IN THE ABSENCE OF OVERT INFLAMMATION. THESE ASPECTS ALSO FORM THE RATIONALE FOR CLINICAL MANAGEMENT OF THE DISEASE. HOWEVER, THE CURRENTLY AVAILABLE THERAPIES TO CONTROL THE DISEASE ARE ONLY PARTIALLY EFFECTIVE AT BEST INDICATING THAT MORE EFFECTIVE THERAPEUTIC SOLUTIONS ARE URGENTLY NEEDED. IT IS APPRECIATED THAT IN THE IMMUNE-DRIVEN AND NEURODEGENERATIVE PROCESSES MS-SPECIFIC DEREGULATION OF GENE EXPRESSIONS AND RESULTING PROTEIN DYSFUNCTION ARE THOUGHT TO PLAY A CENTRAL ROLE. THESE DEVIATIONS IN GENE EXPRESSION PATTERNS CONTRIBUTE TO THE INFLAMMATORY RESPONSE IN THE CNS, AND TO NEURONAL OR AXONAL LOSS. EPIGENETIC MECHANISMS CONTROL TRANSCRIPTION OF MOST, IF NOT ALL GENES, IN NUCLEATED CELLS INCLUDING CELLS OF THE CNS AND IN HAEMATOPOIETIC CELLS. MS-SPECIFIC ALTERATIONS IN EPIGENETIC REGULATION OF GENE EXPRESSION MAY THEREFORE LIE AT THE HEART OF THE DEREGULATION OF GENE EXPRESSION IN MS. AS SUCH, EPIGENETIC MECHANISMS MOST LIKELY PLAY AN IMPORTANT ROLE IN DISEASE PATHOGENESIS. IN THIS REVIEW WE DISCUSS A ROLE FOR MS-SPECIFIC DEREGULATION OF EPIGENETIC FEATURES THAT CONTROL GENE EXPRESSION IN THE CNS AND IN THE PERIPHERY. FURTHERMORE, WE DISCUSS THE APPLICATION OF SMALL MOLECULE INHIBITORS THAT TARGET THE EPIGENETIC MACHINERY TO AMELIORATE DISEASE IN EXPERIMENTAL ANIMAL MODELS, INDICATING THAT SUCH APPROACHES MAY BE APPLICABLE TO MS PATIENTS. 2014 7 4439 38 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 8 3540 36 IMMUNE-DERIVED CYTOKINES IN THE NERVOUS SYSTEM: EPIGENETIC INSTRUCTIVE SIGNALS OR NEUROPATHOGENIC MEDIATORS? THE INVESTIGATION OF THE EFFECTS OF INFLAMMATORY CYTOKINES (IC) ON THE GROWTH AND DIFFERENTIATION OF NEURAL CELLS HAS PROVIDED NEW INSIGHTS ON THE ROLE OF SUCH SOLUBLE MEDIATORS IN NERVOUS SYSTEM DEVELOPMENT AND/OR PLASTIC REMODELING AS WELL AS IN THE PATHOGENESIS OF INFLAMMATORY NEURODEGENERATIVE DISORDERS, WHICH ARE CHARACTERIZED BY CHRONIC IC DYSREGULATION IN THE CENTRAL NERVOUS SYSTEM (CNS). THUS, THE STUDY OF THE INTERACTION BETWEEN CNS AND IMMUNE-DERIVED SOLUBLE SIGNALS IN PHYSIOLOGICAL OR PATHOLOGICAL CONDITIONS IS OF INCREASING INTEREST. THIS REVIEW FIRST DISCUSSES EXPERIMENTAL EVIDENCE SUPPORTING THE INSTRUCTIVE/PERMISSIVE ROLE OF IMMUNE-DERIVED CYTOKINES ON CNS DEVELOPMENT AND PLASTICITY. NEXT, WE FOCUS ON HUMAN NEUROLOGICAL DISEASE STATES SUCH AS MULTIPLE SCLEROSIS AND THE NEURODEGENERATION ASSOCIATED TO THE ACQUIRED IMMUNE DEFICIENCY SYNDROME IN WHICH DIFFERENT INFLAMMATORY CYTOKINES HAVE BEEN PROPOSED AS POTENTIAL NEUROPATHOGENIC MEDIATORS. 1999 9 5369 36 RECENT ADVANCES IN UNDERSTANDING NEUROPATHIC PAIN: GLIA, SEX DIFFERENCES, AND EPIGENETICS. NEUROPATHIC PAIN RESULTS FROM DISEASES OR TRAUMA AFFECTING THE NERVOUS SYSTEM. THIS PAIN CAN BE DEVASTATING AND IS POORLY CONTROLLED. THE PATHOPHYSIOLOGY IS COMPLEX, AND IT IS ESSENTIAL TO UNDERSTAND THE UNDERLYING MECHANISMS IN ORDER TO IDENTIFY THE RELEVANT TARGETS FOR THERAPEUTIC INTERVENTION. IN THIS ARTICLE, WE FOCUS ON THE RECENT RESEARCH INVESTIGATING NEURO-IMMUNE COMMUNICATION AND EPIGENETIC PROCESSES, WHICH GAIN PARTICULAR ATTENTION IN THE CONTEXT OF NEUROPATHIC PAIN. SPECIFICALLY, WE ANALYZE THE ROLE OF GLIAL CELLS, INCLUDING MICROGLIA, ASTROCYTES, AND OLIGODENDROCYTES, IN THE MODULATION OF THE CENTRAL NERVOUS SYSTEM INFLAMMATION TRIGGERED BY NEUROPATHY. CONSIDERING EPIGENETICS, WE ADDRESS DNA METHYLATION, HISTONE MODIFICATIONS, AND THE NON-CODING RNAS IN THE REGULATION OF ION CHANNELS, G-PROTEIN-COUPLED RECEPTORS, AND TRANSMITTERS FOLLOWING NEURONAL DAMAGE. THE GOAL WAS NOT ONLY TO HIGHLIGHT THE EMERGING CONCEPTS BUT ALSO TO DISCUSS CONTROVERSIES, METHODOLOGICAL COMPLICATIONS, AND INTRIGUING OPINIONS. 2016 10 4278 36 MICROGLIAL INNATE MEMORY AND EPIGENETIC REPROGRAMMING IN NEUROLOGICAL DISORDERS. MICROGLIA ARE MYELOID-DERIVED CELLS RECOGNIZED AS BRAIN-RESIDENT MACROPHAGES. THEY ACT AS THE FIRST AND MAIN LINE OF IMMUNE DEFENSE IN THE CENTRAL NERVOUS SYSTEM (CNS). MICROGLIA HAVE HIGH PHENOTYPIC PLASTICITY AND ARE ESSENTIAL FOR REGULATING HEALTHY BRAIN HOMEOSTASIS, AND THEIR DYSREGULATION UNDERLIES THE ONSET AND PROGRESSION OF SEVERAL CNS PATHOLOGIES THROUGH IMPAIRED INFLAMMATORY RESPONSES. ABERRANT MICROGLIAL ACTIVATION, FOLLOWING AN INFLAMMATORY INSULT, IS ASSOCIATED WITH EPIGENETIC DYSREGULATION IN VARIOUS CNS PATHOLOGIES. EMERGING DATA SUGGEST THAT CERTAIN STIMULI TO MYELOID CELLS DETERMINE ENHANCED OR ATTENUATED RESPONSES TO SUBSEQUENT STIMULI. THESE PHENOMENA, GENERALLY TERMED INNATE IMMUNE MEMORY (IIM), ARE HIGHLY DEPENDENT ON EPIGENETIC REPROGRAMMING. MICROGLIAL PRIMING HAS BEEN REPORTED IN SEVERAL NEUROLOGICAL DISEASES AND CORRESPONDS TO A STATE OF INCREASED PERMISSIVENESS OR EXACERBATED RESPONSE, PROMOTED BY CONTINUOUS EXPOSURE TO A CHRONIC PRO-INFLAMMATORY ENVIRONMENT. IN THIS ARTICLE, WE PROVIDE EXTENSIVE EVIDENCE OF THESE EPIGENETIC-MEDIATED PHENOMENA UNDER NEUROLOGICAL CONDITIONS AND DISCUSS THEIR CONTRIBUTION TO PATHOGENESIS AND THEIR CLINICAL IMPLICATIONS, INCLUDING THOSE CONCERNING POTENTIAL NOVEL THERAPEUTIC APPROACHES. 2021 11 5426 41 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 2139 45 EPIGENETIC INSIGHTS INTO MULTIPLE SCLEROSIS DISEASE PROGRESSION. MULTIPLE SCLEROSIS (MS), A CHRONIC INFLAMMATORY DEMYELINATING AND NEURODEGENERATIVE DISEASE OF THE CENTRAL NERVOUS SYSTEM, IS TODAY A LEADING CAUSE OF UNPREDICTABLE LIFELONG DISABILITY IN YOUNG ADULTS. THE TREATMENT OF PATIENTS IN PROGRESSIVE STAGES REMAINS HIGHLY CHALLENGING, ALLUDING TO OUR LIMITED UNDERSTANDING OF THE UNDERLYING PATHOLOGICAL PROCESSES. IN THIS REVIEW, WE PROVIDE INSIGHTS INTO THE MECHANISMS UNDERPINNING MS PROGRESSION FROM A PERSPECTIVE OF EPIGENETICS, THAT REFERS TO STABLE AND MITOTICALLY HERITABLE, YET REVERSIBLE, CHANGES IN THE GENOME ACTIVITY AND GENE EXPRESSION. WE FIRST RECAPITULATE FINDINGS FROM EPIGENETIC STUDIES EXAMINING THE BRAIN TISSUE OF PROGRESSIVE MS PATIENTS, WHICH SUPPORT A CONTRIBUTION OF DNA AND HISTONE MODIFICATIONS IN IMPAIRED OLIGODENDROCYTE DIFFERENTIATION, DEFECTIVE MYELINATION/REMYELINATION AND SUSTAINED NEURO-AXONAL VULNERABILITY. WE NEXT EXPLORE POSSIBILITIES FOR IDENTIFYING FACTORS AFFECTING PROGRESSION USING EASILY ACCESSIBLE TISSUES SUCH AS BLOOD BY COMPARING EPIGENETIC SIGNATURES IN PERIPHERAL IMMUNE CELLS AND BRAIN TISSUE. DESPITE MINOR OVERLAP AT INDIVIDUAL METHYLATION SITES, NEARLY 30% OF ALTERED GENES REPORTED IN PERIPHERAL IMMUNE CELLS OF PROGRESSIVE MS PATIENTS WERE FOUND IN BRAIN TISSUE, JOINTLY CONVERGING ON ALTERATIONS OF NEURONAL FUNCTIONS. WE FURTHER SPECULATE ABOUT THE MECHANISMS UNDERLYING SHARED EPIGENETIC PATTERNS BETWEEN BLOOD AND BRAIN, WHICH LIKELY IMPLY THE INFLUENCE OF INTERNAL (GENETIC CONTROL) AND/OR EXTERNAL (E.G. SMOKING AND AGEING) FACTORS IMPRINTING A COMMON SIGNATURE IN BOTH COMPARTMENTS. OVERALL, WE PROPOSE THAT EPIGENETICS MIGHT SHED LIGHT ON CLINICALLY RELEVANT MECHANISMS INVOLVED IN DISEASE PROGRESSION AND OPEN NEW AVENUES FOR THE TREATMENT OF PROGRESSIVE MS PATIENTS IN THE FUTURE. 2020 13 4536 42 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 14 789 41 CELLULAR AND MOLECULAR MECHANISMS DRIVING NEUROPATHIC PAIN: RECENT ADVANCEMENTS AND CHALLENGES. CURRENT PHARMACOTHERAPEUTICS FOR NEUROPATHIC PAIN OFFER ONLY SYMPTOMATIC RELIEF WITHOUT TREATING THE UNDERLYING PATHOPHYSIOLOGY. ADDITIONALLY, THEY ARE ASSOCIATED WITH VARIOUS DOSE-LIMITING SIDE EFFECTS. PAIN RESEARCH IN THE PAST FEW DECADES HAS REVOLVED AROUND THE ROLE OF OXIDATIVE-NITROSATIVE STRESS, PROTEIN KINASES, GLIAL CELL ACTIVATION, AND INFLAMMATORY SIGNALING CASCADES BUT HAS FAILED TO PRODUCE SPECIFIC AND EFFECTIVE THERAPIES. AREAS COVERED: THIS REVIEW FOCUSES ON RECENT ADVANCES IN CELLULAR AND MOLECULAR MECHANISMS OF NEUROPATHIC PAIN THAT MAY BE TRANSLATED INTO FUTURE THERAPIES. WE DISCUSS EMERGING TARGETS SUCH AS WNT SIGNALING MECHANISMS, THE TETRAHYDROBIOPTERIN PATHWAY, MRG RECEPTORS, ENDOGENOUS LIPID MEDIATORS, MICRO-RNAS AND THEIR ROLES IN PAIN REGULATION. RECENT EVIDENCE IS ALSO PRESENTED REGARDING GENETIC AND EPIGENETIC MECHANISMS OF PAIN MODULATION. EXPERT OPINION: DURING CHRONIC NEUROPATHIC PAIN, MALADAPTATION OCCURS IN THE PERIPHERAL AND CENTRAL NERVOUS SYSTEMS, INCLUDING A SHIFT IN MICROGLIAL PHENOTYPE FROM A SURVEILLANCE STATE TO AN ACTIVATED STATE. MICROGLIAL ACTIVATION LEADS TO AN ALTERED EXPRESSION OF CELL SURFACE PROTEINS, GROWTH FACTORS, AND INTRACELLULAR SIGNALING MOLECULES THAT CONTRIBUTE TO DEVELOPMENT OF A NEUROINFLAMMATORY CASCADE AND CHRONIC PAIN SENSITIZATION. SPECIFIC TARGETING OF THESE CELLULAR AND MOLECULAR MECHANISMS MAY PROVIDE THE KEY TO DEVELOPMENT OF EFFECTIVE NEUROPATHIC PAIN THERAPIES THAT HAVE MINIMAL SIDE EFFECTS. 2018 15 4470 35 MOLECULAR NEUROPATHOLOGY OF ASTROCYTES AND OLIGODENDROCYTES IN ALCOHOL USE DISORDERS. POSTMORTEM STUDIES REVEAL STRUCTURAL AND MOLECULAR ALTERATIONS OF ASTROCYTES AND OLIGODENDROCYTES IN BOTH THE GRAY AND WHITE MATTER (GM AND WM) OF THE PREFRONTAL CORTEX (PFC) IN HUMAN SUBJECTS WITH CHRONIC ALCOHOL ABUSE OR DEPENDENCE. THESE GLIAL CELLULAR CHANGES APPEAR TO PARALLEL AND MAY LARGELY EXPLAIN STRUCTURAL AND FUNCTIONAL ALTERATIONS DETECTED USING NEUROIMAGING TECHNIQUES IN SUBJECTS WITH ALCOHOL USE DISORDERS (AUDS). MOREOVER, DUE TO THE CRUCIAL ROLES OF ASTROCYTES AND OLIGODENDROCYTES IN NEUROTRANSMISSION AND SIGNAL CONDUCTION, THESE CELLS ARE VERY LIKELY MAJOR PLAYERS IN THE MOLECULAR MECHANISMS UNDERPINNING ALCOHOLISM-RELATED CONNECTIVITY DISTURBANCES BETWEEN THE PFC AND RELEVANT INTERCONNECTING BRAIN REGIONS. THE GLIA-MEDIATED ETIOLOGY OF ALCOHOL-RELATED BRAIN DAMAGE IS LIKELY MULTIFACTORIAL SINCE METABOLIC, HORMONAL, HEPATIC AND HEMODYNAMIC FACTORS AS WELL AS DIRECT ACTIONS OF ETHANOL OR ITS METABOLITES HAVE THE POTENTIAL TO DISRUPT DISTINCT ASPECTS OF GLIAL NEUROBIOLOGY. STUDIES IN ANIMAL MODELS OF ALCOHOLISM AND POSTMORTEM HUMAN BRAINS HAVE IDENTIFIED ASTROCYTE MARKERS ALTERED IN RESPONSE TO SIGNIFICANT EXPOSURES TO ETHANOL OR DURING ALCOHOL WITHDRAWAL, SUCH AS GAP-JUNCTION PROTEINS, GLUTAMATE TRANSPORTERS OR ENZYMES RELATED TO GLUTAMATE AND GAMMA-AMINOBUTYRIC ACID (GABA) METABOLISM. CHANGES IN THESE PROTEINS AND THEIR REGULATORY PATHWAYS WOULD NOT ONLY CAUSE GM NEURONAL DYSFUNCTION, BUT ALSO DISTURBANCES IN THE ABILITY OF WM AXONS TO CONVEY IMPULSES. IN ADDITION, ALCOHOLISM ALTERS THE EXPRESSION OF ASTROCYTE AND MYELIN PROTEINS AND OF OLIGODENDROCYTE TRANSCRIPTION FACTORS IMPORTANT FOR THE MAINTENANCE AND PLASTICITY OF MYELIN SHEATHS IN WM AND GM. THESE CHANGES ARE CONCOMITANT WITH EPIGENETIC DNA AND HISTONE MODIFICATIONS AS WELL AS ALTERATIONS IN REGULATORY MICRORNAS (MIRNAS) THAT LIKELY CAUSE PROFOUND DISTURBANCES OF GENE EXPRESSION AND PROTEIN TRANSLATION. KNOWLEDGE IS ALSO AVAILABLE ABOUT INTERACTIONS BETWEEN ASTROCYTES AND OLIGODENDROCYTES NOT ONLY AT THE NODES OF RANVIER (NR), BUT ALSO IN GAP JUNCTION-BASED ASTROCYTE-OLIGODENDROCYTE CONTACTS AND OTHER FORMS OF CELL-TO-CELL COMMUNICATION NOW UNDERSTOOD TO BE CRITICAL FOR THE MAINTENANCE AND FORMATION OF MYELIN. CLOSE INTERACTIONS BETWEEN ASTROCYTES AND OLIGODENDROCYTES ALSO SUGGEST THAT THERAPIES FOR ALCOHOLISM BASED ON A SPECIFIC GLIAL CELL TYPE PATHOLOGY WILL REQUIRE A BETTER UNDERSTANDING OF MOLECULAR INTERACTIONS BETWEEN DIFFERENT CELL TYPES, AS WELL AS CONSIDERING THE POSSIBILITY OF USING COMBINED MOLECULAR APPROACHES FOR MORE EFFECTIVE THERAPIES. 2018 16 4333 38 MICRORNAS: KEY PLAYERS IN MICROGLIA AND ASTROCYTE MEDIATED INFLAMMATION IN CNS PATHOLOGIES. THE SIGNIFICANCE OF MICROGLIA AND ASTROCYTES IN NEURAL DEVELOPMENT, IN MAINTAINING SYNAPTIC CONNECTIONS AND HOMEOSTASIS IN THE HEALTHY BRAIN IS WELL ESTABLISHED. MICROGLIA ARE DYNAMIC IMMUNE CELLS OF THE BRAIN THAT ELICIT AN IMMUNE RESPONSE DURING BRAIN DAMAGE AND ALSO PARTICIPATE IN TISSUE REPAIR AND REGENERATION, WHILE ASTROCYTES CONTRIBUTE TO THE LOCAL INFLAMMATORY RESPONSE BY PRODUCING PROINFLAMMATORY CYTOKINES AND RESOLVING NEURONAL DAMAGE THROUGH PRODUCTION OF ANTI-INFLAMMATORY CYTOKINES AND NEUROTROPHIC FACTORS. RECENT EFFORTS HAVE FOCUSED ON ELUCIDATING THE EPIGENETIC MECHANISMS WHICH REGULATE GLIAL CELL BEHAVIOR IN NORMAL AND PATHOLOGIC STATES. AN IMPORTANT CLASS OF EPIGENETIC REGULATORS IS MICRORNAS (MIRNAS) WHICH ARE SMALL NON-CODING RNA MOLECULES THAT REGULATE GENE EXPRESSION POSTTRANSCRIPTIONALLY. CERTAIN DYSREGULATED MIRNAS CONTRIBUTE TO CHRONIC MICROGLIAL INFLAMMATION IN THE BRAIN, THEREBY LEADING TO PROGRESSION OF NEUROLOGICAL DISEASES LIKE ALZHEIMER'S DISEASE, TRAUMATIC INJURY, AMYOTROPHIC LATERAL SCLEROSIS AND STROKE. FURTHER, SEVERAL MIRNAS ARE DIFFERENTIALLY EXPRESSED IN ASTROCYTES AFTER ISCHEMIA AND SPINAL CORD INJURY. DESPITE KNOWLEDGE ABOUT MIRNAS IN NEUROINFLAMMATION, LITTLE IS KNOWN ABOUT EFFECTIVE DELIVERY ROUTES AND PHARMACOKINETIC DATA FOR MIRNA BASED THERAPEUTICS. THIS REVIEW SUMMARIZES THE CURRENT RESEARCH ON THE ROLE OF MIRNAS IN PROMOTING AND INHIBITING INFLAMMATORY RESPONSE OF MICROGLIA AND ASTROCYTES IN A DISEASE-SPECIFIC MANNER. IN ADDITION, MIRNA DELIVERY AS A THERAPEUTIC STRATEGY TO TREAT NEUROINFLAMMATION IS DISCUSSED. 2016 17 1179 29 CONVERGENCE AND DIVERGENCE IN THE ETIOLOGY OF MYELIN IMPAIRMENT IN PSYCHIATRIC DISORDERS AND DRUG ADDICTION. IMPAIRMENT OF OLIGODENDROGLIA (OL)-DEPENDENT MYELINATION IN THE CENTRAL NERVOUS SYSTEM (CNS) IS A REMARKABLE PARALLEL RECENTLY IDENTIFIED IN MAJOR PSYCHIATRIC DISORDERS AND CHRONIC DRUG ABUSE. NEUROIMAGING AND NEUROPATHOLOGICAL STUDIES REVEALED MYELIN DEFECTS AND MICROARRAY-PROFILING ANALYSIS DEMONSTRATED ABERRANT EXPRESSION OF MYELIN-RELATED GENES IN SCHIZOPHRENIA (SZ), BIPOLAR DISORDER (BD), MAJOR DEPRESSIVE DISORDER (MDD) AND COCAINE ADDICTION. HOWEVER, THE ETIOLOGY UNDERLYING MYELIN IMPAIRMENT IN THESE CLINICALLY DISTINCT SUBJECTS REMAINS ELUSIVE. THIS ARTICLE REVIEWS MYELIN IMPAIRMENT IN LINE WITH DOPAMINERGIC DYSFUNCTION, A PRIME NEUROPATHOPHYSIOLOGICAL TRAIT SHARED IN PSYCHIATRIC DISORDERS AND DRUG ABUSE, AS WELL AS THE GENETIC AND EPIGENETIC ALTERATIONS ASSOCIATED WITH THESE DISEASES. THE CURRENT FINDINGS SUPPORT THE HYPOTHESIS THAT ABERRANT DOPAMINE (DA) ACTION ON OLS IS A COMMON PATHOLOGIC MECHANISM FOR MYELIN IMPAIRMENT IN THE AFOREMENTIONED MENTAL MORBIDITIES, WHEREAS INHERITED GENETIC VARIATIONS THAT SPECIFICALLY AFFECT OL DEVELOPMENT AND MYELINOGENESIS MAY FURTHER INCREASE MYELIN VULNERABILITY IN PSYCHIATRIC DISORDERS. IMPORTANTLY, OL DEFECT IS NOT ONLY A PATHOLOGICAL CONSEQUENCE BUT ALSO A CAUSATIVE FACTOR FOR DOPAMINERGIC DYSFUNCTION. HENCE, MYELIN IMPAIRMENT IS A KEY FACTOR IN THE PATHOGENIC LOOP OF PSYCHIATRIC DISEASES AND DRUG ADDICTION. 2008 18 4721 40 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 19 2856 35 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 20 6003 37 THE ADAPTIVE IMMUNE SYSTEM IN MULTIPLE SCLEROSIS: AN ESTROGEN-MEDIATED POINT OF VIEW. MULTIPLE SCLEROSIS (MS) IS A CHRONIC CENTRAL NERVOUS SYSTEM INFLAMMATORY DISEASE THAT LEADS TO DEMYELINATION AND NEURODEGENERATION. THE THIRD TRIMESTER OF PREGNANCY, WHICH IS CHARACTERIZED BY HIGH LEVELS OF ESTROGENS, HAS BEEN SHOWN TO BE ASSOCIATED WITH REDUCED RELAPSE RATES COMPARED WITH THE RATES BEFORE PREGNANCY. THESE EFFECTS COULD BE RELATED TO THE ANTI-INFLAMMATORY PROPERTIES OF ESTROGENS, WHICH ORCHESTRATE THE RESHUFFLING OF THE IMMUNE SYSTEM TOWARD IMMUNOTOLERANCE TO ALLOW FOR FETAL GROWTH. THE ACTION OF THESE HORMONES IS MEDIATED BY THE TRANSCRIPTIONAL REGULATION ACTIVITY OF ESTROGEN RECEPTORS (ERS). ESTROGEN LEVELS AND ER EXPRESSION DEFINE A SPECIFIC BALANCE OF IMMUNE CELL TYPES. IN THIS REVIEW, WE EXPLORE THE ROLE OF ESTRADIOL (E2) AND ERS IN THE ADAPTIVE IMMUNE SYSTEM, WITH A FOCUS ON ESTROGEN-MEDIATED CELLULAR, MOLECULAR, AND EPIGENETIC MECHANISMS RELATED TO IMMUNE TOLERANCE AND NEUROPROTECTION IN MS. THE EPIGENOME DYNAMICS OF IMMUNE SYSTEMS ARE DESCRIBED AS KEY MOLECULAR MECHANISMS THAT ACT ON THE REGULATION OF IMMUNE CELL IDENTITY. THIS IS A COMPLETELY UNEXPLORED FIELD, SUGGESTING A FUTURE PATH FOR MORE EXTENSIVE RESEARCH ON ESTROGEN-INDUCED COREGULATORY COMPLEXES AND MOLECULAR CIRCUITRY AS TARGETS FOR THERAPEUTICS IN MS. 2019