1 4259 145 METTL3 SUPPRESSES NEUROPATHIC PAIN VIA MODULATING N6-METHYLADENOSINE-DEPENDENT PRIMARY MIR-150 PROCESSING. METHYLTRANSFERASE-LIKE 3 (METTL3)-MODULATED N6-METHYLADENOSINE (M6A) WAS RECENTLY IDENTIFIED AS AN IMPORTANT EPIGENETIC REGULATION TYPE DURING RNA PROCESSING AND CONTRIBUTES TO MULTIPLE PATHOLOGICAL PROCESSES. NEUROPATHIC PAIN (NP) IS INDUCED BY A LESION OF THE SOMATOSENSORY NERVOUS SYSTEM, AND THE DETAILED PATHWAYS BY WHICH METTL3/M6A REGULATED TO MODULATE GENE DYSREGULATION AND ENABLE NP HAVE REMAINED UNCLEAR. THEREFORE, THIS STUDY INVESTIGATED THE FUNCTION OF METTL3-MEDIATED M6A METHYLATION ON MIRNA MATURATION, AND INVESTIGATED HOW THIS REGULATION CONTRIBUTES TO NP PROGRESSION. A RAT MODEL CHARACTERIZED WITH TYPICAL NP WAS ESTABLISHED BY A SPARED NERVE-INJURY (SNI) METHOD. BY ANALYZING THE EXPRESSION LEVELS OF METTL3 AND M6A METHYLATION, WE FOUND THAT METTL3, ALONG WITH M6A METHYLATION, WAS DRAMATICALLY DOWNREGULATED IN NP RATS IN CONTRAST TO THE SHAM ONES. FUNCTIONALLY, ENHANCED METTL3 PROMOTED THE M6A METHYLATION IN TOTAL RNAS AND INHIBITED NP PROGRESSION, WHEREAS SILENCING METTL3 SUPPRESSED M6A METHYLATION AND INCREASED NP SEVERITY. MECHANISTICALLY, METTL3 ACCELERATED MIR-150 MATURATION VIA MEDIATING M6A METHYLATION OF PRIMIR-150 AT LOCUS 498, COOPERATING WITH THE "M6A READER" YTHDF2. MEANWHILE, MIR-150 COULD DIRECTLY TARGET BRAIN-DERIVED NEUROTROPHIC FACTOR (BDNF) MRNA, AND THE METTL3/MIR-150/BDNF REGULATORY PATHWAY WAS FINALLY ESTABLISHED. CLINICALLY, WE PROVED THAT SERUM METTL3 MRNA WAS ALSO DOWNREGULATED IN SHINGLES PATIENTS WITH NP, SUGGESTING ITS DIAGNOSTIC POTENTIAL. IN CONCLUSION, WE DEMONSTRATED AN ESSENTIAL FUNCTION OF METTL3-REGULATED N6-METHYLADENOSINE DURING NP PROGRESSION VIA MODULATING PRIMIR-150 MATURATION. SERUM METTL3 COULD EFFECTIVELY DIFFERENTIATE NP PATIENTS FROM HEALTHY PEOPLE, AND IS USEFUL FOR DYNAMIC MONITORING OF DISEASES AFTER TREATMENT. THEREFORE, THE METTL3/MIR-150/BDNF PATHWAY MAY BE A PROMISING THERAPEUTIC TARGET FOR NP PATIENTS. 2022 2 4644 27 NEUROPATHIC PAIN TREATMENT: STILL A CHALLENGE. NEUROPATHIC PAIN (NP) IS THE RESULT OF A SERIES OF CONDITIONS CAUSED BY DISEASES OR LESIONS TO THE SOMATOSENSORY SYSTEM. DUE TO THE BETTER UNDERSTANDING OF NP PATHOPHYSIOLOGY PREVIOUSLY UNEXPLORED THERAPIES HAVE BEEN USED WITH ENCOURAGING RESULTS. IN THIS GROUP, ACETYL-L-CARNITINE, ALPHA-LIPOIC-ACID, CANNABINOIDS, CLONIDINE, EMA401, BOTULINUM TOXIN TYPE A AND NEW VOLTAGE-GATED SODIUM CHANNEL BLOCKERS, CAN BE INCLUDED. BESIDES, CHANGING PARADIGMS MAY OCCUR WITH THE ADVENT OF OPTOGENETICS AND A BETTER UNDERSTANDING OF EPIGENETIC REGULATION. WE REVIEWED THE PUBLISHED LITERATURE ON THE PHARMACOLOGICAL TREATMENT OF NP. DESPITE THE INTERESTING RESULTS, RANDOMIZED CONTROLLED TRIALS ARE DEMANDED THE MAJORITY OF THE THERAPIES PREVIOUSLY MENTIONED. IN SPITE OF SEVERAL STUDIES FOR THE RELIEF OF NP, PAIN CONTROL CONTINUES BEING A CHALLENGE. 2016 3 5086 30 PILOT STUDY OF DNA METHYLATION IN THE PATHOGENESIS OF CHRONIC RHINOSINUSITIS WITH NASAL POLYPS. BACKGROUND: DNA METHYLATION HAS BEEN IMPLICATED IN THE PATHOGENESIS OF ALLERGY AND ATOPY. THIS STUDY AIMED TO IDENTIFY WHETHER DNA METHYLATION ALSO PLAYS AN IMPORTANT ROLE IN THE PATHOGENESIS OF NASAL POLYPS (NP). METHODOLOGY: NP TISSUES WERE OBTAINED FROM 32 PATIENTS WITH CHRONIC RHINOSINUSITIS WITH BILATERAL NP. BIOPSIES OF INFERIOR TURBINATE MUCOSA (ITM) WERE TAKEN FROM 18 PATIENTS WHO UNDERWENT RHINOSEPTOPLASTY (CONTROL GROUP). THE METHYLATED GENES, WHICH WERE DETECTED BY DNA METHYLATION MICROARRAY, WERE VALIDATED BY METHYLATION-SPECIFIC POLYMERASE CHAIN REACTION, BISULPHITE SEQUENCING, REAL-TIME POLYMERASE CHAIN REACTION AND IMMUNOHISTOCHEMISTRY. RESULTS: DNA METHYLATION MICROARRAY IDENTIFIED 8,008 CPG ISLANDS IN 2,848 GENES. ONE HUNDRED AND NINETY-EIGHT GENES WERE FOUND TO HAVE A METHYLATED SIGNAL IN THE PROMOTER REGION IN NP SAMPLES COMPARED WITH ITM SAMPLES. THE FOUR TOP GENES THAT CHANGED, COL18A1, EP300, GNAS AND SMURF1, WERE SELECTED FOR FURTHER STUDY. THE METHYLATION FREQUENCY OF COL18A1 WAS SIGNIFICANTLY HIGHER IN NP SAMPLES THAN IN ITM SAMPLES. CONCLUSIONS: DNA METHYLATION MIGHT PLAY AN IMPORTANT ROLE IN THE PATHOGENESIS OF NP. PROMOTER METHYLATION OF COL18A1 WAS FOUND TO BE SIGNIFICANTLY INCREASED IN NP TISSUES, FURTHER STUDIES ARE NECESSARY TO CONFIRM THE SIGNIFICANCE OF THESE EPIGENETIC FACTORS IN THE MECHANISMS UNDERLYING THE DEVELOPMENT OR PERSISTENCE OF NP. 2015 4 1564 37 DNA METHYLATION OF PROXIMAL PLAT PROMOTER IN CHRONIC RHINOSINUSITIS WITH NASAL POLYPS. BACKGROUND NASAL POLYPS (NP) ARE CHARACTERIZED BY PSEUDOCYSTS DERIVED FROM STROMAL TISSUE EDEMA AND CAUSE PERSISTENT INFECTIONS IN PATIENTS WITH CHRONIC RHINOSINUSITIS (CRS). A LOW LEVEL OF TISSUE-TYPE PLASMINOGEN ACTIVATOR (GENE NAME PLAT) IS CONSIDERED A CAUSE OF STROMAL TISSUE EDEMA BECAUSE OF INSUFFICIENT PLASMIN ACTIVATION IN NP; HOWEVER, THE MECHANISM REGULATING PLAT GENE EXPRESSION LEVELS IS STILL UNCLEAR. THE EPIGENETIC MECHANISM REGULATING THE PLAT GENE EXPRESSION HAS BEEN STUDIED IN OTHER TISSUES. OBJECTIVE WE AIMED TO INVESTIGATE THE METHYLATION LEVELS IN THE PROXIMAL PLAT PROMOTER AND THEIR EFFECTS ON GENE EXPRESSION IN NP TISSUE. METHODS WE INVESTIGATED THE METHYLATION LEVELS AT 3 CPG SITES IN THE PROXIMAL PLAT PROMOTER REGIONS (-618, -121, AND -105 WITH RESPECT TO THE TRANSCRIPTION INITIATION SITE) BY BISULFITE PYROSEQUENCING AND THEIR EFFECTS ON THE GENE EXPRESSION BY QUANTITATIVE REAL-TIME POLYMERASE CHAIN REACTION (QPCR) IN 20 PAIRED SAMPLES OF NP AND INFERIOR TURBINATE TISSUE (IT) FROM PATIENTS WITH CRS. RESULTS THE DNA METHYLATION LEVELS AT ALL CPG SITES WERE HIGHER ( P < .01), AND THE PLAT EXPRESSION WAS LOWER ( P < .001) IN NP COMPARED WITH IT. THE METHYLATION CHANGES AT THE -618 SITE SHOWED A NEGATIVE CORRELATION WITH THE GENE EXPRESSION CHANGES BETWEEN NP AND IT ( R = -.65, P < .01). CONCLUSIONS HYPERMETHYLATION OF PLAT PROMOTER MAY DOWNREGULATE THE GENE EXPRESSION IN NP, LEADING TO EXCESSIVE FIBRIN DEPOSITION BY ABERRANT COAGULATION CASCADE. DNA METHYLATION OF PROXIMAL PLAT PROMOTER MAY CONTRIBUTE TO NP GROWTH AND HAVE A POTENTIAL AS A NEW THERAPEUTIC TARGET. 2018 5 5553 31 ROLE OF EPIGENETICS IN THE PATHOGENESIS OF CHRONIC RHINOSINUSITIS WITH NASAL POLYPS. CHRONIC RHINOSINUSITIS (CRS) IS A HIGHLY PREVALENT DISEASE CHARACTERIZED BY MUCOSAL INFLAMMATION OF THE NOSE AND PARANASAL SINUSES. CRS CAN BE DIVIDED INTO TWO MAIN CATEGORIES, CRS WITH NASAL POLYPS (NPS; CRSWNP) AND CRS WITHOUT NPS (CRSSNP). ALTHOUGH THE PATHOPHYSIOLOGY OF CRS REMAINS UNCLEAR, DNA METHYLATION HAS BEEN IMPLICATED IN THE ETIOLOGY OF CRSWNP. THE AIM OF THE PRESENT STUDY WAS TO ELUCIDATE WHETHER DNA METHYLATION OF SPECIFIC GENES IS INVOLVED IN THE DEVELOPMENT OF NPS. IN TOTAL, 18 INDIVIDUALS WERE INCLUDED IN THE PRESENT STUDY, AND WERE DIVIDED INTO THREE GROUPS: CRSWNP (N=7), CRSSNP (N=7) AND HEALTHY CONTROLS (N=4). NP TISSUES WERE OBTAINED FROM THE SEVEN PATIENTS WITH CRSWNP AND BIOPSIES OF THE INFERIOR TURBINATE MUCOSA FROM ALL THREE GROUPS WERE USED AS CONTROLS. METHYLATED GENES DETECTED BY METHYL?CPG?BINDING DOMAIN SEQUENCING WERE VALIDATED BY METHYLATION?SPECIFIC POLYMERASE CHAIN REACTION (PCR), BISULFITE SEQUENCING, AND REVERSE TRANSCRIPTION?QUANTITATIVE PCR (RT?QPCR). METHYL?CPG?BINDING DOMAIN SEQUENCING IDENTIFIED 43,674 CPG ISLANDS IN 518 GENES. THE PROMOTOR REGIONS OF 10 AND 30 GENES WERE HYPERMETHYLATED AND HYPOMETHYLATED, RESPECTIVELY, IN NP SAMPLES COMPARED WITH CONTROLS. THE TOP FOUR GENES WITH ALTERED HYPOMETHYLATION IN NP TISSUES WERE, KERATIN 19 (KRT19), NUCLEAR RECEPTOR SUBFAMILY 2 GROUP F MEMBER 2 (NR2F2), A DISINTEGRIN?LIKE AND METALLOPEPTIDASE (REPROLYSIN TYPE) WITH THROMBOSPONDIN TYPE 1 MOTIF 1 (ADAMTS1) AND ZINC FINGER PROTEIN 222 (ZNF222). RT?QPCR DEMONSTRATED THAT THE EXPRESSION LEVELS OF KRT19, NR2F2 AND ADAMTS1 WERE SIGNIFICANTLY INCREASED IN NP TISSUES; HOWEVER, THERE WAS NO DIFFERENCE IN THE LEVELS OF ZNF222 BETWEEN NP AND CONTROL TISSUES. FURTHER STUDIES ARE REQUIRED TO CONFIRM THE RELEVANCE OF THESE EPIGENETIC MODIFICATIONS IN THE MECHANISMS UNDERLYING NP FORMATION. 2018 6 1881 27 EMERGING TREATMENTS FOR NEUROPATHIC PAIN. NEUROPATHIC PAIN IS A SERIES OF WELL-KNOWN CONDITIONS CAUSED BY DISEASES OR LESIONS TO THE SOMATOSENSORY SYSTEM. DUE TO THE BETTER UNDERSTANDING OF THE PATHOPHYSIOLOGY OF NEUROPATHIC PAIN, PREVIOUSLY UNEXPLORED THERAPIES HAVE BEEN USED WITH ENCOURAGING RESULTS. AS SUCH, ACETYL-L-CARNITINE (ALC), ALPHA-LIPOIC-ACID (ALA), CANNABINOIDS, CLONIDINE, EMA401, BOTULINUM TOXIN TYPE A, AND NEW VOLTAGE-GATED SODIUM CHANNEL BLOCKERS, CAN BE CITED. FURTHERMORE, NEW MODALITIES IN NEUROMODULATION SUCH AS HIGH-FREQUENCY SPINAL CORD STIMULATION, BURST STIMULATION, DORSAL ROOT GANGLION STIMULATION, TRANSCRANIAL DIRECT CURRENT STIMULATION, AND MANY OTHERS HAVE BEEN SHOWING EXCITING RESULTS. BESIDES, CHANGING PARADIGMS MAY OCCUR WITH THE ADVENT OF OPTOGENETICS AND A BETTER UNDERSTANDING OF EPIGENETIC REGULATION. THIS ARTICLE REVIEWS THE PUBLISHED LITERATURE ON THE TREATMENT OF NP. DESPITE THE INTERESTING RESULTS, RANDOMIZED CONTROLLED TRIALS ARE DEMANDED FOR THE MAJORITY OF THE THERAPIES PREVIOUSLY MENTIONED. 2015 7 885 41 CHRONIC CONSTRICTION INJURY-INDUCED CHANGES IN CIRCULAR RNA EXPRESSION PROFILING OF THE DORSAL ROOT GANGLION IN A RAT MODEL OF NEUROPATHIC PAIN. BACKGROUND: THE PATHOGENESIS OF NEUROPATHIC PAIN (NP) HAS NOT BEEN FULLY ELUCIDATED. GENE CHANGES IN DORSAL ROOT GANGLIA (DRG) MAY CONTRIBUTE TO THE DEVELOPMENT OF NP. CIRCULAR RNAS (CIRCRNAS) ARE A CLASS OF ENDOGENOUS NONCODING RNAS THAT FORM COVALENTLY CLOSED LOOP STRUCTURES AND ARE CRUCIAL FOR GENETIC AND EPIGENETIC REGULATION. HOWEVER, LITTLE IS KNOWN ABOUT CIRCRNA CHANGES IN DRG NEURONS AFTER PERIPHERAL NERVE INJURY. METHODS: A SCIATIC NERVE CHRONIC CONSTRICTION INJURY (CCI) MODEL WAS ESTABLISHED TO INDUCE NEUROPATHIC PAIN. WE PERFORMED GENOME-WIDE CIRCRNA ANALYSIS OF FOUR PAIRED DORSAL ROOT GANGLION (DRG) SAMPLES (L4-L5) FROM CCI AND NEGATIVE CONTROL (NC) RATS USING NEXT-GENERATION SEQUENCING TECHNOLOGY. THE DIFFERENTIALLY EXPRESSED CIRCRNAS (DECIRCRNAS) WERE IDENTIFIED BY DIFFERENTIAL EXPRESSION ANALYSIS, AND THE EXPRESSION PROFILE OF CIRCRNAS WAS VALIDATED BY QUANTITATIVE PCR. GENE ONTOLOGY AND KYOTO ENCYCLOPEDIA OF GENES AND GENOMES ANALYSES WERE PERFORMED TO PREDICT THE FUNCTION OF DECIRCRNAS. RESULTS: A TOTAL OF 374 DECIRCRNAS WERE IDENTIFIED BETWEEN CCI AND NC RATS USING CIRCRNA HIGH-THROUGHPUT SEQUENCING. AMONG THEM, 290 WERE UPREGULATED AND 84 WERE DOWNREGULATED IN THE CCI GROUP. THE EXPRESSION LEVELS OF NINE DECIRCRNAS WERE VALIDATED BY QPCR. FUNCTIONAL ANNOTATION ANALYSIS SHOWED THAT THE DECIRCRNAS WERE MAINLY ENRICHED IN PATHWAYS AND FUNCTIONS, INCLUDING 'DOPAMINERGIC SYNAPSE,' 'RENIN SECRETION,' 'MITOGEN-ACTIVATED PROTEIN KINASE SIGNALING PATHWAY,' AND 'NEUROGENESIS.' COMPETING ENDOGENOUS RNA ANALYSIS SHOWED THAT THE TOP 50 CIRCRNAS EXHIBITED INTERACTIONS WITH FOUR PAIN-RELATED MICRORNAS (MIRNAS). CIRC:CHR2:33950934-33955969 WAS THE LARGEST NODE IN THE CIRCRNA-MIRNA INTERACTION NETWORK. CONCLUSIONS: PERIPHERAL NERVE INJURY-INDUCED NEUROPATHIC PAIN LED TO CHANGES IN THE COMPREHENSIVE EXPRESSION PROFILE OF CIRCRNAS IN THE DRG OF RATS. DECIRCRNAS MAY ADVANCE OUR UNDERSTANDING OF THE MOLECULAR MECHANISMS UNDERLYING NEUROPATHIC PAIN. 2022 8 2834 48 FOLIC ACID MODULATES MATRIX METALLOPROTEINASE-2 EXPRESSION, ALLEVIATES NEUROPATHIC PAIN, AND IMPROVES FUNCTIONAL RECOVERY IN SPINAL CORD-INJURED RATS. BACKGROUND: THE MOLECULAR UNDERPINNINGS OF SPINAL CORD INJURY (SCI) ASSOCIATED WITH NEUROPATHIC PAIN (NP) ARE UNKNOWN. RECENT STUDIES HAVE DEMONSTRATED THAT MATRIX METALLOPROTEINASES (MMPS) SUCH AS MMP2 PLAY A CRITICAL ROLE IN INDUCING NP FOLLOWING SCI. PROMOTER METHYLATION OF MMPS IS KNOWN TO SUPPRESS THEIR TRANSCRIPTION AND REDUCE NP. IN THIS CONTEXT, IT HAS BEEN SHOWN IN RODENTS THAT FOLIC ACID (FA), AN FDA APPROVED DIETARY SUPPLEMENT AND KEY METHYL DONOR IN THE CENTRAL NERVOUS SYSTEM (CNS), INCREASES AXONAL REGENERATION AND REPAIR OF INJURED CNS IN PART VIA METHYLATION. PURPOSE: BASED ON ABOVE OBSERVATIONS, IN THIS STUDY, WE TEST WHETHER FA COULD DECREASE MMP2 EXPRESSION AND THEREBY DECREASE SCI-INDUCED NP. METHODS: SPRAGUE-DAWLEY MALE RATS WEIGHING 250-270 G RECEIVED CONTUSION SPINAL CORD INJURIES (CSCIS) WITH A CUSTOM SPINAL CORD IMPACTOR DEVICE THAT DROPS A 10 G WEIGHT FROM A HEIGHT OF 12.5 MM. THE INJURED RATS RECEIVED EITHER I.P. INJECTIONS OF FA (80 MICROG/KG) OR WATER (CONTROL) 3 DAYS PRIOR AND 17 DAYS POST-CSCI (MID PHASE) OR FOR 3 DAYS PRE-CSCI AND 14 DAYS POST-CSCI ENDING ON THE 42ND DAY OF CSCI (LATE PHASE). THE FUNCTIONAL NEUROLOGICAL DEFICITS DUE TO CSCI WERE THEN ASSESSED BY BASSO, BEATTIE, AND BRESNAHAN (BBB) SCORES EITHER ON POST-IMPACTION DAYS 0 THROUGH 18 POST-CSCI (MID PHASE) OR ON DAYS 0, 2, 7, 14, 21, 28, 35, AND 42 (LATE PHASE). BASELINE MEASUREMENTS WERE TAKEN THE DAY BEFORE STARTING TREATMENTS. THERMAL HYPERALGESIA (TH) TESTING FOR PAIN WAS PERFORMED ON 4 DAYS PRE-CSCI (BASELINE DATA) AND ON DAYS 18, 21, 28, 35, AND 42 POST-CSCI. FOLLOWING TH TESTING, ANIMALS WERE EUTHANIZED AND SPINAL CORDS HARVESTED FOR MMP-2 EXPRESSION ANALYSIS. RESULT: THE FA-TREATED GROUPS SHOWED HIGHER BBB SCORES DURING MID PHASE (DAY 18) AND IN LATE PHASE (DAY 42) OF INJURY COMPARED TO CONTROLS, SUGGESTING ENHANCED FUNCTIONAL RECOVERY. THERE IS A TRANSIENT DECLINE IN TH IN ANIMALS FROM THE FA-TREATED GROUP COMPARED TO CONTROLS WHEN TESTED ON DAYS 18, 21, 28, AND 35, INDICATIVE OF A DECREASE IN NP. HOWEVER, WHEN TESTED 25 DAYS AFTER STOPPING FA ADMINISTRATION ON DAY 42 OF CSCI, NO SIGNIFICANT DIFFERENCE IN TH WAS OBSERVED BETWEEN FA-TREATED AND CONTROL ANIMALS. WESTERN BLOT ANALYSIS OF THE INJURED SPINAL CORD FROM FA-TREATED ANIMALS SHOWED SIGNIFICANT DECLINE IN MMP2 EXPRESSION COMPARED TO SPINAL CORD SAMPLES FROM WATER-TREATED CONTROLS. CONCLUSION: TOGETHER, THESE DATA SUGGEST THAT FA COULD ALLEVIATE NP AND IMPROVE FUNCTIONAL RECOVERY POST-SCI, POSSIBLY BY REDUCING THE EXPRESSION OF MMP2. FURTHER STUDIES WILL OPEN UP A NOVEL AND EASY NATURAL THERAPY, IDEAL FOR CLINICAL TRANSLATION WITH MINIMAL SIDE EFFECTS, FOR MANAGING SCI-INDUCED NP. SUCH STUDIES MIGHT ALSO THROW LIGHT ON A POSSIBLE EPIGENETIC MECHANISM IN FA-INDUCED RECOVERY AFTER SCI. 2017 9 4579 30 N(6)-METHYLADENOSINE METHYLASE METTL3 CONTRIBUTES TO NEUROPATHIC PAIN BY EPIGENETIC SILENCING OF MU OPIOID RECEPTOR. WE AIMED AT EXPLORING THE ROLE AND MECHANISM OF METTL3-MEDIATED M(6)A MODIFICATION IN NEUROPATHIC PAIN. MALE SPRAGUE-DAWLEY RATS WERE RANDOMLY DIVIDED INTO FOUR GROUPS: SHAM OPERATION GROUP (SHAM GROUP), CHRONIC CONSTRICTION INJURY (CCI) OF THE SCIATIC NERVE MODEL GROUP (NPP GROUP), INTRATHECAL INJECTION OF VIRUS DOWN-REGULATED METTL3 + CCI MODEL GROUP (M3 + NPP GROUP) AND INTRATHECAL INJECTION OF NEGATIVE CONTROL VIRUS + CCI MODEL GROUP (SCR + NPP GROUP). THE M3 + NPP GROUP AND THE SCR + NPP GROUP WERE INTRATHECALLY INJECTED WITH VIRUS NINETEEN DAYS BEFORE OPERATION. THE PAW WITHDRAWAL MECHANICAL THRESHOLDS AND PAW WITHDRAWAL LATENCY WERE RESPECTIVELY RECORDED ONE DAY BEFORE OPERATION, THREE DAYS, FIVE DAYS AND SEVEN DAYS AFTER OPERATION. THE RATS WERE SACRIFICED ON THE SEVENTH DAY AFTER OPERATION, AND THEIR SPINAL CORD TISSUES WERE TAKEN. THE FROZEN SECTIONS OF RATS WERE PERFORMED TO OBSERVE THE EXPRESSION OF GREEN FLUORESCENT PROTEIN OF THE VIRUS. THE METHYLATION LEVEL OF RNA, THE PROTEIN EXPRESSION OF M(6)A-RELATED ENZYME (METTL3) AND MU OPIOID RECEPTOR (MOR) IN SPINAL CORD TISSUES OF THE FOUR GROUPS WERE MEASURED. DOWNREGULATION OF METTL3 HAD NO EFFECT ON THE OVERALL METHYLATION LEVEL OF THE SPINAL CORD, BUT IT COULD REGULATE THE METHYLATION LEVEL OF THE OPRM1 GENE RNA ENCODING MOR, PARTIALLY RESTORE THE EXPRESSION OF MOR, AND RELIEVE PAIN IN RATS. IN THE PROCESS OF NPP, METTL3 MAY INHIBIT THE EXPRESSION OF MOR BY REGULATING THE METHYLATION LEVEL OF OPRM1 GENE RNA ENCODING MOR, AND ULTIMATELY PROMOTE THE OCCURRENCE AND DEVELOPMENT OF NPP. 2023 10 1612 30 DNA METHYLATION: A TARGET IN NEUROPATHIC PAIN. NEUROPATHIC PAIN (NP), CAUSED BY AN INJURY OR A DISEASE AFFECTING THE SOMATOSENSORY NERVOUS SYSTEM OF THE CENTRAL AND PERIPHERAL NERVOUS SYSTEMS, HAS BECOME A GLOBAL HEALTH CONCERN. RECENT STUDIES HAVE DEMONSTRATED THAT EPIGENETIC MECHANISMS ARE AMONG THOSE THAT UNDERLIE NP; THUS, ELUCIDATING THE MOLECULAR MECHANISM OF DNA METHYLATION IS CRUCIAL TO DISCOVERING NEW THERAPEUTIC METHODS FOR NP. IN THIS REVIEW, WE FIRST BRIEFLY DISCUSS DNA METHYLATION, DEMETHYLATION, AND THE ASSOCIATED KEY ENZYMES, SUCH AS METHYLASES AND DEMETHYLASES. WE THEN DISCUSS THE RELATIONSHIP BETWEEN NP AND DNA METHYLATION, FOCUSING ON DNA METHYLTRANSFERASES INCLUDING METHYL-CPG-BINDING DOMAIN (MBD) FAMILY PROTEINS AND TEN-ELEVEN TRANSLOCATION (TET) ENZYMES. BASED ON EXPERIMENTAL RESULTS OF NEURALGIA IN ANIMAL MODELS, THE MECHANISM OF DNA METHYLATION-RELATED NEURALGIA IS SUMMARIZED, AND USEFUL TARGETS FOR EARLY DRUG INTERVENTION IN NP ARE DISCUSSED. 2022 11 6461 38 TIME-COURSE PROGRESSION OF WHOLE TRANSCRIPTOME EXPRESSION CHANGES OF TRIGEMINAL GANGLIA COMPARED TO DORSAL ROOT GANGLIA IN RATS EXPOSED TO NERVE INJURY. MECHANISMS UNDERLYING NEUROPATHIC PAIN (NP) ARE COMPLEX WITH MULTIPLE GENES, THEIR INTERACTIONS, ENVIRONMENTAL AND EPIGENETIC FACTORS BEING IMPLICATED. TRANSCRIPTIONAL CHANGES IN THE TRIGEMINAL (TG) AND DORSAL ROOT (DRG) GANGLIA HAVE BEEN IMPLICATED IN THE DEVELOPMENT AND MAINTENANCE OF NP. DESPITE EFFORTS TO UNRAVEL MOLECULAR MECHANISMS OF NP, MANY REMAIN UNKNOWN. ALSO, MOST OF THE STUDIES FOCUSED ON THE SPINAL SYSTEM. ALTHOUGH THE SPINAL AND TRIGEMINAL SYSTEMS SHARE SOME OF THE MOLECULAR MECHANISMS, DIFFERENCES EXIST. WE USED RNA-SEQUENCING TECHNOLOGY TO IDENTIFY DIFFERENTIALLY EXPRESSED GENES (DEGS) IN THE TG AND DRG AT BASELINE AND 3 TIME-POINTS FOLLOWING THE INFRAORBITAL OR SCIATIC NERVE INJURIES, RESPECTIVELY. PATHWAY ANALYSIS AND COMPARISON ANALYSIS WERE PERFORMED TO IDENTIFY DIFFERENTIALLY EXPRESSED PATHWAYS. ADDITIONALLY, UPSTREAM REGULATOR EFFECTS WERE INVESTIGATED IN THE TWO SYSTEMS. DEG (DIFFERENTIALLY EXPRESSED GENES) ANALYSES IDENTIFIED 3,225 GENES TO BE DIFFERENTIALLY EXPRESSED BETWEEN TG AND DRG IN NAIVE ANIMALS, 1,828 GENES FOUR DAYS POST INJURY, 5,644 AT DAY 8 AND 9,777 DEGS AT 21 DAYS POST INJURY. COMPARISON OF TOP ENRICHED CANONICAL PATHWAYS REVEALED THAT A NUMBER OF SIGNALING PATHWAY WAS SIGNIFICANTLY INHIBITED IN THE TG AND ACTIVATED IN THE DRG AT 21 DAYS POST INJURY. FINALLY, CORT UPSTREAM REGULATOR WAS PREDICTED TO BE INHIBITED IN THE TG WHILE EXPRESSION LEVELS OF CSF1 UPSTREAM REGULATOR WERE SIGNIFICANTLY ELEVATED IN THE DRG AT 21 DAYS POST INJURY. THIS STUDY PROVIDES A BASIS FOR FURTHER IN-DEPTH STUDIES INVESTIGATING TRANSCRIPTIONAL CHANGES, PATHWAYS, AND UPSTREAM REGULATION IN TG AND DRG IN RATS EXPOSED TO PERIPHERAL NERVE INJURIES. 2023 12 2407 37 EPIGENETIC RESTORATION OF VOLTAGE-GATED POTASSIUM CHANNEL KV1.2 ALLEVIATES NERVE INJURY-INDUCED NEUROPATHIC PAIN. VOLTAGE-GATED POTASSIUM CHANNELS (KV) ARE IMPORTANT REGULATORS OF NEURONAL EXCITABILITY FOR ITS ROLE OF REGULATING RESTING MEMBRANE POTENTIAL AND REPOLARIZATION. RECENT STUDIES SHOW THAT KV CHANNELS PARTICIPATE IN NEUROPATHIC PAIN, BUT THE DETAILED UNDERLYING MECHANISMS ARE FAR FROM BEING CLEAR. IN THIS STUDY, WE USED SIRNA, MIR-137 AGOMIR, AND ANTAGOMIR TO REGULATE THE EXPRESSION OF KV1.2 IN SPINAL CORD AND DORSAL ROOT GANGLIA (DRG) OF NAIVE AND CHRONIC CONSTRICTION INJURY (CCI) RATS. KV CURRENTS AND NEURON EXCITABILITY IN DRG NEURONS WERE EXAMINED BY PATCH-CLAMP WHOLE-CELL RECORDING TO VERIFY THE CHANGE IN KV1.2 FUNCTION. THE RESULTS SHOWED THAT KV1.2 WAS DOWN-REGULATED IN DRG AND SPINAL DORSAL HORN (SDH) BY CCI. KNOCKDOWN OF KV1.2 BY INTRATHECALLY INJECTING KCNA2 SIRNA INDUCED SIGNIFICANT MECHANICAL AND THERMAL HYPERSENSITIVITY IN NAIVE RATS. CONCOMITANT WITH THE DOWN-REGULATION OF KV1.2 WAS AN INCREASE IN THE EXPRESSION OF THE MIR-137. THE TARGETING AND REGULATING OF MIR-137 ON KCNA2 WAS VERIFIED BY DUAL-LUCIFERASE REPORTER SYSTEM AND INTRATHECAL INJECTING MIR-137 AGOMIR. FURTHERMORE, RESCUING THE EXPRESSION OF KV1.2 IN CCI RATS, ACHIEVED THROUGH INHIBITING MIR-137, RESTORED THE ABNORMAL KV CURRENTS AND EXCITABILITY IN DRG NEURONS, AND ALLEVIATED MECHANICAL ALLODYNIA AND THERMAL HYPERALGESIA. THESE RESULTS INDICATE THAT THE MIR-137-MEDIATED KV1.2 IMPAIRMENT IS A CRUCIAL ETIOPATHOGENESIS FOR THE NERVE INJURY-INDUCED NEUROPATHIC PAIN AND CAN BE A NOVEL POTENTIAL THERAPEUTIC TARGET FOR NEUROPATHIC PAIN MANAGEMENT. 2021 13 5574 35 ROLE OF MICRORNA-143 IN NERVE INJURY-INDUCED UPREGULATION OF DNMT3A EXPRESSION IN PRIMARY SENSORY NEURONS. PERIPHERAL NERVE INJURY INCREASED THE EXPRESSION OF THE DNA METHYLTRANSFERASE 3A (DNMT3A) MRNA AND ITS ENCODING DNMT3A PROTEIN IN INJURED DORSAL ROOT GANGLIA (DRG). THIS INCREASE IS CONSIDERED AS AN ENDOGENOUS INSTIGATOR IN NEUROPATHIC PAIN GENESIS THROUGH EPIGENETIC SILENCING OF PAIN-ASSOCIATED GENES (SUCH AS OPRM1) IN INJURED DRG. HOWEVER, HOW DRG DNMT3A IS INCREASED FOLLOWING PERIPHERAL NERVE INJURY IS STILL ELUSIVE. WE REPORTED HERE THAT PERIPHERAL NERVE INJURY CAUSED BY THE FIFTH SPINAL NERVE LIGATION (SNL) DOWNREGULATED MICRORNA (MIR)-143 EXPRESSION IN INJURED DRG. THIS DOWNREGULATION WAS REQUIRED FOR SNL-INDUCED DRG DNMT3A INCREASE AS RESCUING MIR-143 DOWNREGULATION THROUGH MICROINJECTION OF MIR-143 MIMICS INTO INJURED DRG BLOCKED THE SNL-INDUCED INCREASE IN DNMT3A AND RESTORED THE SNL-INDUCED DECREASES IN OPRM1 MRNA AND ITS ENCODING MU OPIOID RECEPTOR (MOR) IN INJURED DRG, IMPAIRED SPINAL CORD CENTRAL SENSITIZATION AND NEUROPATHIC PAIN, AND IMPROVED MORPHINE ANALGESIC EFFECTS FOLLOWING SNL. MIMICKING SNL-INDUCED DRG MIR-143 DOWNREGULATION THROUGH DRG MICROINJECTION OF MIR143 INHIBITORS IN NAIVE RATS INCREASED THE EXPRESSION OF DNMT3A AND REDUCED THE EXPRESSION OF OPRM1 MRNA AND MOR IN INJECTED DRG AND PRODUCED NEUROPATHIC PAIN-LIKE SYMPTOMS. THESE FINDINGS SUGGEST THAT MIR-143 IS A NEGATIVE REGULATOR IN DNMT3A EXPRESSION IN THE DRG UNDER NEUROPATHIC PAIN CONDITIONS AND MAY BE A POTENTIAL TARGET FOR THERAPEUTIC MANAGEMENT OF NEUROPATHIC PAIN. 2017 14 2272 41 EPIGENETIC REDUCTION OF MIR-214-3P UPREGULATES ASTROCYTIC COLONY-STIMULATING FACTOR-1 AND CONTRIBUTES TO NEUROPATHIC PAIN INDUCED BY NERVE INJURY. EMERGING EVIDENCE HAS INDICATED THAT COLONY-STIMULATING FACTOR-1 (CSF1) MODULATES NEUROINFLAMMATION IN THE CENTRAL NERVOUS SYSTEM AND THE DEVELOPMENT OF NEUROPATHIC PAIN, WHILE THE UNDERLYING MECHANISM REMAINS UNKNOWN. HERE, WE IDENTIFIED THE INCREASED EXPRESSION OF CSF1 DERIVED FROM ACTIVATED ASTROCYTES IN THE IPSILATERAL DORSAL HORN IN RATS WITH SPINAL NERVE LIGATION (SNL). SUPPRESSION OF CSF1 EXPRESSION ALLEVIATED NEUROINFLAMMATION, NEURONAL HYPEREXCITABILITY, AND GLUTAMATERGIC RECEPTOR SUBUNIT UPREGULATION IN THE DORSAL HORN AND IMPROVED SNL-INDUCED PAIN BEHAVIOR. WE ALSO FOUND REDUCED MIR-214-3P EXPRESSION IN THE IPSILATERAL DORSAL HORN FOLLOWING AN SNL PROCEDURE; MIR-214-3P DIRECTLY BOUND TO THE 3'-UTR OF CSF1 MRNA AND NEGATIVELY REGULATED CSF1 EXPRESSION. INTRATHECAL DELIVERY OF MIR-214-3P MIMIC REVERSED THE ENHANCED EXPRESSION OF CSF1 AND ASTROCYTE OVERACTIVITY AND ALLEVIATED THE IL-6 UPREGULATION AND PAIN BEHAVIOR INDUCED BY SNL. MOREOVER, SUPPRESSION OF SPINAL MIR-214-3P INCREASED ASTROCYTE REACTIVITY, PROMOTED CSF1 AND IL-6 PRODUCTION, AND INDUCED PAIN HYPERSENSITIVITY IN NAIVE ANIMALS. FURTHERMORE, SNL INDUCED THE EXPRESSION OF DNA METHYLTRANSFERASE 3A (DNMT3A) THAT WAS ASSOCIATED WITH THE HYPERMETHYLATION OF THE MIR-214-3P PROMOTER, LEADING TO REDUCED MIR-214-3P EXPRESSION IN THE MODEL RODENTS. TREATMENT WITH THE DNMT INHIBITOR ZEBULARINE SIGNIFICANTLY REDUCED CYTOSINE METHYLATION IN THE MIR-214-3P PROMOTER; THIS REDUCED METHYLATION CONSEQUENTLY INCREASED THE EXPRESSION OF MIR-214-3P AND DECREASED THE CONTENT OF CSF1 IN THE IPSILATERAL DORSAL HORN AND, FURTHER, ATTENUATED IL-6 PRODUCTION AND PAIN BEHAVIOR IN RATS WITH SNL. TOGETHER, OUR DATA INDICATE THAT THE DNMT3A-MEDIATED EPIGENETIC SUPPRESSION OF MIR-214-3P ENHANCED CSF1 PRODUCTION IN ASTROCYTES, WHICH SUBSEQUENTLY INDUCED NEUROINFLAMMATION AND PAIN BEHAVIOR IN SNL MODEL RATS. 2020 15 5347 43 RARBETA AGONIST DRUG (C286) DEMONSTRATES EFFICACY IN A PRE-CLINICAL NEUROPATHIC PAIN MODEL RESTORING MULTIPLE PATHWAYS VIA DNA REPAIR MECHANISMS. NEUROPATHIC PAIN (NP) IS ASSOCIATED WITH PROFOUND GENE EXPRESSION ALTERATIONS WITHIN THE NOCICEPTIVE SYSTEM. DNA MECHANISMS, SUCH AS EPIGENETIC REMODELING AND REPAIR PATHWAYS HAVE BEEN IMPLICATED IN NP. HERE WE HAVE USED A RAT MODEL OF PERIPHERAL NERVE INJURY TO STUDY THE EFFECT OF A RECENTLY DEVELOPED RARBETA AGONIST, C286, CURRENTLY UNDER CLINICAL RESEARCH, IN NP. A 4-WEEK TREATMENT INITIATED 2 DAYS AFTER THE INJURY NORMALIZED PAIN SENSATION. GENOME-WIDE AND PATHWAY ENRICHMENT ANALYSIS SHOWED THAT MULTIPLE MECHANISMS PERSISTENTLY ALTERED IN THE SPINAL CORD WERE RESTORED TO PREINJURY LEVELS BY THE AGONIST. CONCOMITANT UPREGULATION OF DNA REPAIR PROTEINS, ATM AND BRCA1, THE LATTER BEING REQUIRED FOR C286-MEDIATED PAIN MODULATION, SUGGESTS THAT EARLY DNA REPAIR MAY BE IMPORTANT TO PREVENT PHENOTYPIC EPIGENETIC IMPRINTS IN NP. THUS, C286 IS A PROMISING DRUG CANDIDATE FOR NEUROPATHIC PAIN AND DNA REPAIR MECHANISMS MAY BE USEFUL THERAPEUTIC TARGETS TO EXPLORE. 2019 16 5692 38 SILENCING OF LNCRNA PKIA-AS1 ATTENUATES SPINAL NERVE LIGATION-INDUCED NEUROPATHIC PAIN THROUGH EPIGENETIC DOWNREGULATION OF CDK6 EXPRESSION. NEUROPATHIC PAIN (NP) IS AMONG THE MOST INTRACTABLE COMORBIDITIES OF SPINAL CORD INJURY. DYSREGULATION OF NON-CODING RNAS HAS ALSO BEEN IMPLICATED IN THE DEVELOPMENT OF NEUROPATHIC PAIN. HERE, WE IDENTIFIED A NOVEL LNCRNA, PKIA-AS1, BY USING LNCRNA ARRAY ANALYSIS IN SPINAL CORD TISSUE OF SPINAL NERVE LIGATION (SNL) MODEL RATS, AND INVESTIGATED THE ROLE OF PKIA-AS1 IN SNL-MEDIATED NEUROPATHIC PAIN. WE OBSERVED THAT PKIA-AS1 WAS SIGNIFICANTLY UPREGULATED IN SNL MODEL RATS AND THAT PKIA-AS1 KNOCKDOWN ATTENUATED NEUROPATHIC PAIN PROGRESSION. ALTERNATIVELY, OVEREXPRESSION OF PKIA-AS1 WAS SUFFICIENT TO INDUCE NEUROPATHIC PAIN-LIKE SYMPTOMS IN UNINJURED RATS. WE ALSO FOUND THAT PKIA-AS1 MEDIATED SNL-INDUCED NEUROPATHIC PAIN BY DIRECTLY REGULATING THE EXPRESSION AND FUNCTION OF CDK6, WHICH IS ESSENTIAL FOR THE INITIATION AND MAINTENANCE OF NEUROINFLAMMATION AND NEUROPATHIC PAIN. THEREFORE, OUR STUDY IDENTIFIES PKIA-AS1 AS A NOVEL THERAPEUTIC TARGET FOR NEUROINFLAMMATION RELATED NEUROPATHIC PAIN. 2019 17 3810 38 INTRATHECAL 5-AZACYTIDINE INHIBITS GLOBAL DNA METHYLATION AND METHYL- CPG-BINDING PROTEIN 2 EXPRESSION AND ALLEVIATES NEUROPATHIC PAIN IN RATS FOLLOWING CHRONIC CONSTRICTION INJURY. THE PATHOGENESIS OF NEUROPATHIC PAIN REMAINS LARGELY UNKNOWN. EPIGENETIC MECHANISMS MAY PLAY A MAJOR ROLE IN REGULATING EXPRESSION OF PRO- OR ANTINOCICEPTIVE GENES. DNA METHYLATION IS A MAJOR EPIGENETIC MECHANISM IN VERTEBRATES, AND METHYL- CPG-BINDING PROTEIN 2 (MECP2) IS DIRECTLY INVOLVED IN METHYLATION-MEDIATED GENE SILENCING. TO DETERMINE HOW CHANGES IN GLOBAL DNA METHYLATION AND MECP2 EXPRESSION OCCUR FOLLOWING CHRONIC CONSTRICTION INJURY (CCI) AND HOW REPRESSION OF DNA METHYLATION AFFECTS THESE CHANGES AND ATTENUATES NEUROPATHIC PAIN, WE USED INTRATHECAL 5-AZACYTIDINE, A DNA METHYLTRANSFERASE INHIBITOR, IN CCI RATS. RATS RECEIVED 0.9% SALINE OR 5-AZACYTIDINE (10MUMOL.D(-1)) VIA SPINAL INJECTION ONCE DAILY FROM DAY 3 TO DAY 14 AFTER CCI SURGERY. GLOBAL DNA METHYLATION AND MECP2 EXPRESSION INCREASED IN THE SPINAL CORD IN CCI RATS ON DAY 14 AFTER CCI SURGERY. MECHANICAL ALLODYNIA AND THERMAL HYPERALGESIA INDUCED BY CCI WERE ATTENUATED BY INTRATHECAL 5-AZACYTIDINE FROM DAY 5 TO DAY 14 AFTER CCI SURGERY. THE INCREASES IN GLOBAL DNA METHYLATION AND MECP2 EXPRESSION IN THE SPINAL CORD IN CCI RATS WERE ALSO SIGNIFICANTLY INHIBITED BY INTRATHECAL 5-AZACYTIDINE. THESE RESULTS DEMONSTRATE THAT INCREASED GLOBAL DNA METHYLATION AND MECP2 EXPRESSION IN THE SPINAL CORD AFTER NERVE DAMAGE MAY PLAY AN IMPORTANT ROLE IN NEUROPATHIC PAIN. 5-AZACYTIDINE SHOWS POTENTIAL FOR TREATING NEUROPATHIC PAIN. 2011 18 3809 49 INTRAPERITONEAL 5-AZACYTIDINE ALLEVIATES NERVE INJURY-INDUCED PAIN IN RATS BY MODULATING DNA METHYLATION. TO INVESTIGATE THE ROLE OF DNA METHYLATION IN MODULATING CHRONIC NEUROPATHIC PAIN (NPP), IDENTIFY POSSIBLE TARGET GENES OF DNA METHYLATION INVOLVED IN THIS PROCESS, AND PRELIMINARILY CONFIRM THE MEDICINAL VALUE OF THE DNA METHYLTRANSFERASES (DNMTS) INHIBITOR 5-AZACYTIDINE (5-AZA) IN NPP BY TARGETING GENE METHYLATION. TWO RAT NPP MODELS, CHRONIC CONSTRICTION INJURY (CCI) AND SPINAL NERVE LIGATION (SNL), WERE USED. THE DNA METHYLATION PROFILES IN THE LUMBAR SPINAL CORD WERE ASSAYED USING AN ARRAYSTAR RAT REFSEQ PROMOTER ARRAY. THE UNDERLYING GENES WITH DIFFERENTIAL METHYLATION WERE THEN IDENTIFIED AND SUBMITTED TO GENE ONTOLOGY AND PATHWAY ANALYSIS. METHYL-DNA IMMUNOPRECIPITATION QUANTITATIVE PCR (MEDIP-QPCR) AND QUANTITATIVE REVERSE TRANSCRIPTION-PCR (RT-QPCR) WERE USED TO CONFIRM GENE METHYLATION AND EXPRESSION. THE PROTECTIVE FUNCTION OF 5-AZA IN NPP AND GENE EXPRESSION WERE EVALUATED VIA BEHAVIORAL ASSAYS AND RT-QPCR, RESPECTIVELY. ANALYSIS OF THE DNA METHYLATION PATTERNS IN THE LUMBAR SPINAL CORD INDICATED THAT 1205 DIFFERENTIALLY METHYLATED FRAGMENTS IN CCI RATS WERE LOCATED WITHIN DNA PROMOTER REGIONS, INCLUDING 638 HYPERMETHYLATED FRAGMENTS AND 567 HYPOMETHYLATED FRAGMENTS. THE METHYLATION LEVELS OF GRM4, HTR4, ADRB2, KCNF1, GAD2, AND PPARG, WHICH ARE ASSOCIATED WITH LONG-TERM POTENTIATION (LTP) AND GLUTAMATERGIC SYNAPSE PATHWAYS, WERE INCREASED WITH A CORRESPONDING DECREASE IN THEIR MRNA EXPRESSION, IN THE SPINAL CORDS OF CCI RATS. MOREOVER, WE FOUND THAT THE INTRAPERITONEAL INJECTION OF 5-AZA (4 MG/KG) ATTENUATED CCI- OR SNL-INDUCED MECHANICAL ALLODYNIA AND THERMAL HYPERALGESIA. FINALLY, THE MRNA EXPRESSION OF HYPERMETHYLATED GENES SUCH AS GRM4, HTR4, ADRB2, KCNF1, AND GAD2 WAS REVERSED AFTER 5-AZA TREATMENT. CCI INDUCED WIDESPREAD METHYLATION CHANGES IN THE DNA PROMOTER REGIONS IN THE LUMBAR SPINAL CORD. INTRAPERITONEAL 5-AZA ALLEVIATED HYPERALGESIA IN CCI AND SNL RATS, AN EFFECT ACCOMPANIED BY THE REVERSED EXPRESSION OF HYPERMETHYLATED GENES. THUS, DNA METHYLATION INHIBITION REPRESENTS A PROMISING EPIGENETIC STRATEGY FOR PROTECTION AGAINST CHRONIC NPP FOLLOWING NERVE INJURY. OUR STUDY LAYS A THEORETICAL FOUNDATION FOR 5-AZA TO BECOME A CLINICAL TARGETED DRUG. 2023 19 3146 35 GLOBAL RESEARCH TRENDS ON EPIGENETICS AND NEUROPATHIC PAIN: A BIBLIOMETRIC ANALYSIS. OBJECTIVE: NEUROPATHIC PAIN (NP) IS A COMMON DISEASE THAT MANIFESTS WITH PATHOLOGICAL CHANGES IN THE SOMATOSENSORY SYSTEM. IN RECENT YEARS, THE INTERACTIONS OF NP WITH THE EPIGENETIC MECHANISM HAVE BEEN INCREASINGLY ELUCIDATED. HOWEVER, ONLY A FEW STUDIES HAVE USED BIBLIOMETRIC TOOLS TO SYSTEMATICALLY ANALYZE KNOWLEDGE IN THIS FIELD. THE OBJECTIVE OF THIS STUDY IS TO VISUALLY ANALYZE THE TRENDS, HOTSPOTS, AND FRONTIERS IN EPIGENETICS AND NP RESEARCH BY USING A BIBLIOMETRIC METHOD. METHODS: STUDIES RELATED TO EPIGENETICS AND NP WERE SEARCHED FROM THE SCIENCE CITATION INDEX-EXPANDED OF THE WEB OF SCIENCE CORE COLLECTION DATABASE. SEARCH TIME IS FROM INCEPTION TO NOVEMBER 30, 2022. NO RESTRICTIONS WERE PLACED ON LANGUAGE. ONLY ARTICLES AND REVIEWS WERE INCLUDED AS DOCUMENT TYPES. DATA ON INSTITUTIONS, COUNTRIES, AUTHORS, JOURNAL DISTRIBUTION, AND KEYWORDS WERE IMPORTED INTO CITESPACE SOFTWARE FOR VISUAL ANALYSIS. RESULTS: A TOTAL OF 867 PUBLICATIONS MET THE INCLUSION CRITERIA, WHICH SPANNED THE PERIOD FROM 2000 TO 2022. OVER THE YEARS, THE NUMBER OF PUBLICATIONS AND THE FREQUENCY OF CITATIONS EXHIBITED A CLEAR UPWARD TREND IN GENERAL, REACHING A PEAK IN 2021. THE MAJOR CONTRIBUTING COUNTRIES IN TERMS OF THE NUMBER OF PUBLICATIONS WERE CHINA, THE UNITED STATES, AND JAPAN. THE TOP THREE INSTITUTIONS WERE RUTGERS STATE UNIVERSITY, XUZHOU MEDICAL UNIVERSITY, AND NANJING MEDICAL UNIVERSITY. MOLECULAR PAIN, PAIN, AND JOURNAL OF NEUROINFLAMMATION CONTRIBUTED SIGNIFICANTLY TO THE VOLUME OF ISSUES. AMONG THE TOP 10 AUTHORS IN TERMS OF THE NUMBER OF PUBLICATIONS, TAO YUAN-XIANG CONTRIBUTED 30 ENTRIES, FOLLOWED BY ZHANG YI WITH 24 AND WU SHAO-GEN WITH 20. ON THE BASIS OF THE BURST AND CLUSTERS OF KEYWORDS, "DNA METHYLATION," "CIRCULAR RNA," "ACETYLATION," "LONG NON-CODING RNA," AND "MICROGLIA" ARE GLOBAL HOTSPOTS IN THE FIELD. CONCLUSION: THE BIBLIOMETRIC ANALYSIS INDICATES THAT THE NUMBER OF PUBLICATIONS RELATED TO EPIGENETICS AND NP IS EXHIBITING A RAPID INCREASE. KEYWORD ANALYSIS SHOWS THAT "DNA METHYLATION," "CIRCULAR RNA," "ACETYLATION," "LONG NON-CODING RNA" AND "MICROGLIA" ARE THE MOST INTERESTING TERMS FOR RESEARCHERS IN THE FIELD. MORE RIGOROUS CLINICAL TRIALS AND ADDITIONAL STUDIES THAT EXPLORE RELEVANT MECHANISMS ARE REQUIRED IN THE FUTURE. 2023 20 2112 25 EPIGENETIC GENE SILENCING UNDERLIES C-FIBER DYSFUNCTIONS IN NEUROPATHIC PAIN. PERIPHERAL NERVE INJURY CAUSES NEUROPATHIC PAIN, WHICH IS CHARACTERIZED BY THE PARADOXICAL SENSATIONS OF POSITIVE AND NEGATIVE SYMPTOMS. CLINICALLY, NEGATIVE SIGNS ARE FREQUENTLY OBSERVED; HOWEVER, THEIR UNDERLYING MOLECULAR MECHANISMS ARE LARGELY UNKNOWN. DYSFUNCTION OF C-FIBERS IS ASSUMED TO UNDERLIE NEGATIVE SYMPTOMS AND IS ACCOMPANIED BY LONG-LASTING DOWNREGULATION OF NA(V)1.8 SODIUM CHANNEL AND MU-OPIOID RECEPTOR (MOP) IN THE DORSAL ROOT GANGLION (DRG). IN THE PRESENT STUDY, WE FOUND THAT NERVE INJURY UPREGULATES NEURON-RESTRICTIVE SILENCER FACTOR (NRSF) EXPRESSION IN THE DRG NEURONS MEDIATED THROUGH EPIGENETIC MECHANISMS. IN ADDITION, CHROMATIN IMMUNOPRECIPITATION ANALYSIS REVEALED THAT NERVE INJURY PROMOTES NRSF BINDING TO THE NEURON-RESTRICTIVE SILENCER ELEMENT WITHIN MOP AND NA(V)1.8 GENES, THEREBY CAUSING EPIGENETIC SILENCING. FURTHERMORE, NRSF KNOCKDOWN SIGNIFICANTLY BLOCKED NERVE INJURY-INDUCED DOWNREGULATIONS OF MOP AND NA(V)1.8 GENE EXPRESSIONS, C-FIBER HYPOESTHESIA, AND THE LOSSES OF PERIPHERAL MORPHINE ANALGESIA AND NA(V)1.8-SELECTIVE BLOCKER-INDUCED HYPOESTHESIA. TOGETHER, THESE DATA SUGGEST THAT NRSF CAUSES PATHOLOGICAL AND PHARMACOLOGICAL DYSFUNCTION OF C-FIBERS, WHICH UNDERLIES THE NEGATIVE SYMPTOMS IN NEUROPATHIC PAIN. 2010