1 4879 80 OVERLAPPING SIGNATURES OF CHRONIC PAIN IN THE DNA METHYLATION LANDSCAPE OF PREFRONTAL CORTEX AND PERIPHERAL T CELLS. WE TESTED THE HYPOTHESIS THAT EPIGENETIC MECHANISMS IN THE BRAIN AND THE IMMUNE SYSTEM ARE ASSOCIATED WITH CHRONIC PAIN. GENOME-WIDE DNA METHYLATION ASSESSED IN 9 MONTHS POST NERVE-INJURY (SNI) AND SHAM RATS, IN THE PREFRONTAL CORTEX (PFC) AS WELL AS IN T CELLS REVEALED A VAST DIFFERENCE IN THE DNA METHYLATION LANDSCAPE IN THE BRAIN BETWEEN THE GROUPS AND A REMARKABLE OVERLAP (72%) BETWEEN DIFFERENTIALLY METHYLATED PROBES IN T CELLS AND PREFRONTAL CORTEX. DNA METHYLATION STATES IN THE PFC SHOWED ROBUST CORRELATION WITH PAIN SCORE OF ANIMALS IN SEVERAL GENES INVOLVED IN PAIN. FINALLY, ONLY 11 DIFFERENTIALLY METHYLATED PROBES IN T CELLS WERE SUFFICIENT TO DISTINGUISH SNI OR SHAM INDIVIDUAL RATS. THIS STUDY SUPPORTS THE PLAUSIBILITY OF DNA METHYLATION INVOLVEMENT IN CHRONIC PAIN AND DEMONSTRATES THE POTENTIAL FEASIBILITY OF DNA METHYLATION MARKERS IN T CELLS AS NONINVASIVE BIOMARKERS OF CHRONIC PAIN SUSCEPTIBILITY. 2016 2 6427 31 THE TRANSITION FROM ACUTE TO CHRONIC PAIN: DYNAMIC EPIGENETIC REPROGRAMMING OF THE MOUSE PREFRONTAL CORTEX UP TO 1 YEAR AFTER NERVE INJURY. CHRONIC PAIN IS ASSOCIATED WITH PERSISTENT STRUCTURAL AND FUNCTIONAL CHANGES THROUGHOUT THE NEUROAXIS, INCLUDING IN THE PREFRONTAL CORTEX (PFC). THE PFC IS IMPORTANT IN THE INTEGRATION OF SENSORY, COGNITIVE, AND EMOTIONAL INFORMATION AND IN CONDITIONED PAIN MODULATION. WE PREVIOUSLY REPORTED WIDESPREAD EPIGENETIC REPROGRAMMING IN THE PFC MANY MONTHS AFTER NERVE INJURY IN RODENTS. EPIGENETIC MODIFICATIONS, INCLUDING DNA METHYLATION, CAN DRIVE CHANGES IN GENE EXPRESSION WITHOUT MODIFYING DNA SEQUENCES. TO DATE, LITTLE IS KNOWN ABOUT EPIGENETIC DYSREGULATION AT THE ONSET OF ACUTE PAIN OR HOW IT PROGRESSES AS PAIN TRANSITIONS FROM ACUTE TO CHRONIC. WE HYPOTHESIZE THAT ACUTE PAIN AFTER INJURY RESULTS IN RAPID AND PERSISTENT EPIGENETIC REMODELLING IN THE PFC THAT EVOLVES AS PAIN BECOMES CHRONIC. WE FURTHER PROPOSE THAT UNDERSTANDING EPIGENETIC REMODELLING WILL PROVIDE INSIGHTS INTO THE MECHANISMS DRIVING PAIN-RELATED CHANGES IN THE BRAIN. EPIGENOME-WIDE ANALYSIS WAS PERFORMED IN THE MOUSE PFC 1 DAY, 2 WEEKS, 6 MONTHS, AND 1 YEAR AFTER PERIPHERAL INJURY USING THE SPARED NERVE INJURY IN MICE. SPARED NERVE INJURY RESULTED IN RAPID AND PERSISTENT CHANGES IN DNA METHYLATION, WITH ROBUST DIFFERENTIAL METHYLATION OBSERVED BETWEEN SPARED NERVE INJURY AND SHAM-OPERATED CONTROL MICE AT ALL TIME POINTS. HUNDREDS OF DIFFERENTIALLY METHYLATED GENES WERE IDENTIFIED, INCLUDING MANY WITH KNOWN FUNCTION IN PAIN. PATHWAY ANALYSIS REVEALED ENRICHMENT IN GENES RELATED TO STIMULUS RESPONSE AT EARLY TIME POINTS, IMMUNE FUNCTION AT LATER TIME POINTS, AND ACTIN AND CYTOSKELETAL REGULATION THROUGHOUT THE TIME COURSE. THESE RESULTS EMPHASIZE THE IMPORTANCE OF CONSIDERING PAIN CHRONICITY IN BOTH PAIN RESEARCH AND IN TREATMENT OPTIMIZATION. 2020 3 5007 29 PERIPHERAL NERVE INJURY IS ASSOCIATED WITH CHRONIC, REVERSIBLE CHANGES IN GLOBAL DNA METHYLATION IN THE MOUSE PREFRONTAL CORTEX. CHANGES IN BRAIN STRUCTURE AND CORTICAL FUNCTION ARE ASSOCIATED WITH MANY CHRONIC PAIN CONDITIONS INCLUDING LOW BACK PAIN AND FIBROMYALGIA. THE MAGNITUDE OF THESE CHANGES CORRELATES WITH THE DURATION AND/OR THE INTENSITY OF CHRONIC PAIN. MOST STUDIES REPORT CHANGES IN COMMON AREAS INVOLVED IN PAIN MODULATION, INCLUDING THE PREFRONTAL CORTEX (PFC), AND PAIN-RELATED PATHOLOGICAL CHANGES IN THE PFC CAN BE REVERSED WITH EFFECTIVE TREATMENT. WHILE THE MECHANISMS UNDERLYING THESE CHANGES ARE UNKNOWN, THEY MUST BE DYNAMICALLY REGULATED. EPIGENETIC MODULATION OF GENE EXPRESSION IN RESPONSE TO EXPERIENCE AND ENVIRONMENT IS REVERSIBLE AND DYNAMIC. EPIGENETIC MODULATION BY DNA METHYLATION IS ASSOCIATED WITH ABNORMAL BEHAVIOR AND PATHOLOGICAL GENE EXPRESSION IN THE CENTRAL NERVOUS SYSTEM. DNA METHYLATION MIGHT ALSO BE INVOLVED IN MEDIATING THE PATHOLOGIES ASSOCIATED WITH CHRONIC PAIN IN THE BRAIN. WE THEREFORE TESTED A) WHETHER ALTERATIONS IN DNA METHYLATION ARE FOUND IN THE BRAIN LONG AFTER CHRONIC NEUROPATHIC PAIN IS INDUCED IN THE PERIPHERY USING THE SPARED NERVE INJURY MODAL AND B) WHETHER THESE INJURY-ASSOCIATED CHANGES ARE REVERSIBLE BY INTERVENTIONS THAT REVERSE THE PATHOLOGIES ASSOCIATED WITH CHRONIC PAIN. SIX MONTHS FOLLOWING PERIPHERAL NERVE INJURY, ABNORMAL SENSORY THRESHOLDS AND INCREASED ANXIETY WERE ACCOMPANIED BY DECREASED GLOBAL METHYLATION IN THE PFC AND THE AMYGDALA BUT NOT IN THE VISUAL CORTEX OR THE THALAMUS. ENVIRONMENTAL ENRICHMENT ATTENUATED NERVE INJURY-INDUCED HYPERSENSITIVITY AND REVERSED THE CHANGES IN GLOBAL PFC METHYLATION. FURTHERMORE, GLOBAL PFC METHYLATION CORRELATED WITH MECHANICAL AND THERMAL SENSITIVITY IN NEUROPATHIC MICE. IN SUMMARY, INDUCTION OF CHRONIC PAIN BY PERIPHERAL NERVE INJURY IS ASSOCIATED WITH EPIGENETIC CHANGES IN THE BRAIN. THESE CHANGES ARE DETECTED LONG AFTER THE ORIGINAL INJURY, AT A LONG DISTANCE FROM THE SITE OF INJURY AND ARE REVERSIBLE WITH ENVIRONMENTAL MANIPULATION. CHANGES IN BRAIN STRUCTURE AND CORTICAL FUNCTION THAT ARE ASSOCIATED WITH CHRONIC PAIN CONDITIONS MAY THEREFORE BE MEDIATED BY EPIGENETIC MECHANISMS. 2013 4 344 24 ALTERED BDNF METHYLATION IN PATIENTS WITH CHRONIC MUSCULOSKELETAL PAIN AND HIGH BIOPSYCHOSOCIAL COMPLEXITY. PURPOSE: THE INTERMED INSTRUMENT, WHICH WAS DEVELOPED TO MEASURE PATIENT'S BIOPSYCHOSOCIAL (BPS) COMPLEXITY, REPRESENTS A POWERFUL DIAGNOSTIC AND THERAPEUTIC TOOL. EPIGENETIC CHANGES ARE THE INTERFACE BETWEEN SIGNALS FROM THE ENVIRONMENT AND GENETIC MODIFICATIONS, AFFECTING GENE EXPRESSION, IN PARTICULAR, BY DNA METHYLATION OF CPG DINUCLEOTIDES IN PROMOTOR REGIONS OF THE CORRESPONDING GENES. THE BRAIN-DERIVED NEUROTROPHIC FACTOR (BDNF) GENE PLAYS A CRUCIAL ROLE IN THE CENTRAL SENSITIZATION (CS) OF PAIN. IN THIS STUDY, WE HYPOTHESIZED THAT CHRONIC PAIN MODIFIES THE METHYLATION LEVELS OF THE BDNF GENE IN A MANNER THAT IS INTERCONNECTED WITH THE BPS STATUS. PATIENTS AND METHODS: FIFTY-EIGHT CHRONIC MUSCULOSKELETAL PAIN PATIENTS (CMSP) WERE ENROLLED IN THE STUDY. DNA WAS EXTRACTED FROM BLOOD SAMPLES, THE METHYLATION LEVELS OF 13 CPG SITES IN THE BDNF PROMOTER WERE MEASURED BY PYROSEQUENCING, AND ASSOCIATION STUDIES WITH VARIOUS PATIENT PARAMETERS AND THE INTERMED SCORES WERE PERFORMED. RESULTS: INTERESTINGLY, A NEGATIVE CORRELATION (-0.40) WAS FOUND BETWEEN THE TOTAL INTERMED SCORES AND THE AVERAGE CPG METHYLATION VALUES OF THE BDNF GENE, BUT NO CORRELATION WAS OBSERVED WITH THE SEVERITY OF PAIN, DEGREE OF ANXIETY, DEPRESSION, OR KINESIOPHOBIA AND CATASTROPHISM. MOREOVER, THE ASSOCIATION WAS INDEPENDENT OF AGE, SEX AND LEVEL OF COMORBIDITIES. CONCLUSION: THIS RESULT SHOWS THAT CMSP, IN ASSOCIATION WITH ITS BIOPSYCHOSOCIAL CONTEXT, EPIGENETICALLY DECREASES THE DEGREE OF METHYLATION OF THE BDNF PROMOTER AND SHOULD THEREFORE INCREASE THE LEVEL OF BDNF TRANSCRIPTION. IT ALSO SUGGESTS A ROLE OF THE INTERMED TOOL TO DETECT A RELATIONSHIP BETWEEN THE BPS COMPLEXITY AND THE EPIGENETIC CONTROL OF A TARGET GENE. THE POSSIBLE UPREGULATION OF BDNF EXPRESSION MIGHT BE, AT LEAST IN PART, THE SIGNAL FOR CHRONIC PAIN-INDUCED CENTRAL SENSITIZATION (CS). THIS COULD PARTLY EXPLAIN WHY PATIENTS WITH A HIGHER LEVEL OF COMPLEXITY FEEL MORE PAIN THAN THOSE WITH LOWER COMPLEXITY. 2020 5 990 19 CHRONIC SOCIAL STRESS INDUCES DNA METHYLATION CHANGES AT AN EVOLUTIONARY CONSERVED INTERGENIC REGION IN CHROMOSOME X. CHRONIC STRESS RESULTING FROM PROLONGED EXPOSURE TO NEGATIVE LIFE EVENTS INCREASES THE RISK OF MOOD AND ANXIETY DISORDERS. ALTHOUGH CHRONIC STRESS CAN CHANGE GENE EXPRESSION RELEVANT FOR BEHAVIOR, MOLECULAR REGULATORS OF THIS CHANGE HAVE NOT BEEN FULLY DETERMINED. ONE PROCESS THAT COULD PLAY A ROLE IS DNA METHYLATION, AN EPIGENETIC PROCESS WHEREBY A METHYL GROUP IS ADDED ONTO NUCLEOTIDES, PREDOMINANTLY CYTOSINE IN THE CPG CONTEXT, AND WHICH CAN BE INDUCED BY CHRONIC STRESS. IT IS UNKNOWN TO WHAT EXTENT CHRONIC SOCIAL DEFEAT, A MODEL OF HUMAN SOCIAL STRESS, INFLUENCES DNA METHYLATION PATTERNS ACROSS THE GENOME. OUR STUDY ADDRESSED THIS QUESTION BY USING A TARGETED-CAPTURE APPROACH CALLED METHYL-SEQ TO INVESTIGATE DNA METHYLATION PATTERNS OF THE DENTATE GYRUS AT PUTATIVE REGULATORY REGIONS ACROSS THE MOUSE GENOME FROM MICE EXPOSED TO 14 DAYS OF SOCIAL DEFEAT. FINDINGS WERE REPLICATED IN INDEPENDENT COHORTS BY BISULFITE-PYROSEQUENCING. TWO DIFFERENTIALLY METHYLATED REGIONS (DMRS) WERE IDENTIFIED. ONE DMR WAS LOCATED AT INTRON 9 OF DROSHA, AND IT SHOWED REDUCED METHYLATION IN STRESSED MICE. THIS OBSERVATION REPLICATED IN ONE OF TWO INDEPENDENT COHORTS. A SECOND DMR WAS IDENTIFIED AT AN INTERGENIC REGION OF CHROMOSOME X, AND METHYLATION IN THIS REGION WAS INCREASED IN STRESSED MICE. THIS METHYLATION DIFFERENCE REPLICATED IN TWO INDEPENDENT COHORTS AND IN MAJOR DEPRESSIVE DISORDER (MDD) POSTMORTEM BRAINS. THESE RESULTS HIGHLIGHT A REGION NOT PREVIOUSLY KNOWN TO BE DIFFERENTIALLY METHYLATED BY CHRONIC SOCIAL DEFEAT STRESS AND WHICH MAY BE INVOLVED IN MDD. 2018 6 6246 33 THE METHYL DONOR S-ADENOSYL METHIONINE REVERSES THE DNA METHYLATION SIGNATURE OF CHRONIC NEUROPATHIC PAIN IN MOUSE FRONTAL CORTEX. CHRONIC PAIN IS ASSOCIATED WITH PERSISTENT BUT REVERSIBLE STRUCTURAL AND FUNCTIONAL CHANGES IN THE PREFRONTAL CORTEX (PFC). THIS STABLE YET MALLEABLE PLASTICITY IMPLICATES EPIGENETIC MECHANISMS, INCLUDING DNA METHYLATION, AS A POTENTIAL MEDIATOR OF CHRONIC PAIN-INDUCED CORTICAL PATHOLOGY. WE PREVIOUSLY DEMONSTRATED THAT CHRONIC ORAL ADMINISTRATION OF THE METHYL DONOR S-ADENOSYL METHIONINE (SAM) ATTENUATES LONG-TERM PERIPHERAL NEUROPATHIC PAIN AND ALTERS GLOBAL FRONTAL CORTICAL DNA METHYLATION. HOWEVER, THE SPECIFIC GENES AND PATHWAYS ASSOCIATED WITH THE RESOLUTION OF CHRONIC PAIN BY SAM REMAIN UNEXPLORED. OBJECTIVE: TO DETERMINE THE EFFECT OF LONG-TERM THERAPEUTIC EXPOSURE TO SAM ON THE DNA METHYLATION OF INDIVIDUAL GENES AND PATHWAYS IN A MOUSE NEUROPATHIC PAIN MODEL. METHODS: MALE CD-1 MICE RECEIVED SPARED NERVE INJURY OR SHAM SURGERY. THREE MONTHS AFTER INJURY, ANIMALS RECEIVED SAM (20 MG/KG, ORAL, 3X A WEEK) OR VEHICLE FOR 16 WEEKS FOLLOWED BY EPIGENOME-WIDE ANALYSIS OF FRONTAL CORTEX. RESULTS: PERIPHERAL NEUROPATHIC PAIN WAS ASSOCIATED WITH 4000 DIFFERENTIALLY METHYLATED GENOMIC REGIONS THAT WERE ENRICHED IN INTRACELLULAR SIGNALING, CELL MOTILITY AND MIGRATION, CYTOSKELETAL STRUCTURE, AND CELL ADHESION PATHWAYS. A THIRD OF THESE DIFFERENTIALLY METHYLATED REGIONS WERE REVERSED BY SAM TREATMENT (1415 REGIONS REPRESENTING 1013 GENES). MORE THAN 100 GENES WITH KNOWN PAIN-RELATED FUNCTION WERE DIFFERENTIALLY METHYLATED AFTER NERVE INJURY; 29 OF THESE WERE REVERSED BY SAM TREATMENT INCLUDING SCN10A, TRPA1, NTRK1, AND GFAP. CONCLUSION: THESE RESULTS SUGGEST A ROLE FOR THE EPIGENOME IN THE MAINTENANCE OF CHRONIC PAIN AND ADVANCE EPIGENETIC MODULATORS SUCH AS SAM AS A NOVEL APPROACH TO TREAT CHRONIC PAIN. 2021 7 2078 26 EPIGENETIC DIVERGENCE IN THE TRPA1 PROMOTER CORRELATES WITH PRESSURE PAIN THRESHOLDS IN HEALTHY INDIVIDUALS. THE EXPRESSION PATTERN OF IMPORTANT TRANSDUCTION MOLECULES IN NOCICEPTIVE SENSORY NEURONS IS LIKELY TO DICTATE PAIN SENSITIVITY. WHILE THIS NOTION IS WELL ESTABLISHED FOR INCREASED PAIN SENSITIVITIES UNDER CONDITIONS LIKE INFLAMMATION AND NEUROPATHY, LESS IS KNOWN AS TO WHICH MOLECULES ARE DEFINING INTERINDIVIDUAL DIFFERENCES IN PAIN SENSITIVITY IN HEALTHY SUBJECTS. A GENOME-WIDE METHYLATION ANALYSIS ON MONOZYGOTIC TWINS FOUND THAT METHYLATION OF A CPG DINUCLEOTIDE IN THE PROMOTER OF TRANSIENT RECEPTOR POTENTIAL ANKYRIN 1 (TRPA1) IS INVERSELY ASSOCIATED WITH THE THRESHOLD FOR HEAT-INDUCED PAIN. SEVERAL IN VITRO STUDIES ALSO SUGGEST THAT TRPA1 MEDIATES MECHANICAL SENSITIVITY OF SENSORY AFFERENTS, THUS POTENTIALLY MEDIATING PRESSURE-EVOKED PAIN. IN THE PRESENT STUDY, WE THEREFORE INVESTIGATED THE EPIGENETIC PREDISPOSITION FOR PRESSURE PAIN BY ANALYZING THE METHYLATION STATUS OF 47 CPG SITES IN THE PROMOTER REGION OF TRPA1. USING DNA FROM WHOLE-BLOOD SAMPLES OF 75 HEALTHY VOLUNTEERS, WE FOUND THAT THE SAME CPG SITE PREVIOUSLY FOUND TO AFFECT THE THRESHOLD FOR HEAT-EVOKED PAIN IS HYPERMETHYLATED IN SUBJECTS WITH A LOW THRESHOLD FOR PRESSURE PAIN. WE ALSO FOUND GENDER DIFFERENCES, WITH FEMALES DISPLAYING HIGHER METHYLATION RATES COMBINED WITH HIGHER PRESSURE PAIN SENSITIVITIES AS COMPARED WITH MALES. IN CONCLUSION, OUR FINDINGS SUPPORT THE NOTION THAT EPIGENETIC REGULATION OF TRPA1 SEEMS TO REGULATE THERMAL AND MECHANICAL PAIN SENSITIVITIES. 2017 8 531 32 ASTROCYTE REACTIVITY FOLLOWING BLAST EXPOSURE INVOLVES ABERRANT HISTONE ACETYLATION. BLAST INDUCED NEUROTRAUMA (BINT) IS A PREVALENT INJURY WITHIN MILITARY AND CIVILIAN POPULATIONS. THE INJURY IS CHARACTERIZED BY PERSISTENT INFLAMMATION AT THE CELLULAR LEVEL WHICH MANIFESTS AS A MULTITUDE OF COGNITIVE AND FUNCTIONAL IMPAIRMENTS. EPIGENETIC REGULATION OF TRANSCRIPTION OFFERS AN IMPORTANT CONTROL MECHANISM FOR GENE EXPRESSION AND CELLULAR FUNCTION WHICH MAY UNDERLIE CHRONIC INFLAMMATION AND RESULT IN NEURODEGENERATION. WE HYPOTHESIZE THAT ALTERED HISTONE ACETYLATION PATTERNS MAY BE INVOLVED IN BLAST INDUCED INFLAMMATION AND THE CHRONIC ACTIVATION OF GLIAL CELLS. THIS STUDY AIMED TO ELUCIDATE CHANGES TO HISTONE ACETYLATION OCCURRING FOLLOWING INJURY AND THE ROLES THESE CHANGES MAY HAVE WITHIN THE PATHOLOGY. SPRAGUE DAWLEY RATS WERE SUBJECTED TO EITHER A 10 OR 17 PSI BLAST OVERPRESSURE WITHIN AN ADVANCED BLAST SIMULATOR (ABS). SHAM ANIMALS UNDERWENT THE SAME PROCEDURES WITHOUT BLAST EXPOSURE. MEMORY IMPAIRMENTS WERE MEASURED USING THE NOVEL OBJECT RECOGNITION (NOR) TEST AT 2 AND 7 DAYS POST-INJURY. TISSUES WERE COLLECTED AT 7 DAYS FOR WESTERN BLOT AND IMMUNOHISTOCHEMISTRY (IHC) ANALYSIS. SHAM ANIMALS SHOWED INTACT MEMORY AT EACH TIME POINT. THE NOVEL OBJECT DISCRIMINATION DECREASED SIGNIFICANTLY BETWEEN TWO AND 7 DAYS FOR EACH INJURY GROUP (P < 0.05). THIS IS INDICATIVE OF THE ONSET OF MEMORY IMPAIRMENT. WESTERN BLOT ANALYSIS SHOWED GLIAL FIBRILLARY ACIDIC PROTEIN (GFAP), A KNOWN MARKER OF ACTIVATED ASTROCYTES, WAS ELEVATED IN THE PREFRONTAL CORTEX (PFC) FOLLOWING BLAST EXPOSURE FOR BOTH INJURY GROUPS. ANALYSIS OF HISTONE PROTEIN EXTRACT SHOWED NO CHANGES IN THE LEVEL OF ANY TOTAL HISTONE PROTEINS WITHIN THE PFC. HOWEVER, ACETYLATION LEVELS OF HISTONE H2B, H3, AND H4 WERE DECREASED IN BOTH GROUPS (P < 0.05). CO-LOCALIZATION IMMUNOFLUORESCENCE WAS USED TO FURTHER INVESTIGATE ANY POTENTIAL CORRELATION BETWEEN DECREASED HISTONE ACETYLATION AND ASTROCYTE ACTIVATION. THESE EXPERIMENTS SHOWED A SIMILAR DECREASE IN H3 ACETYLATION IN ASTROCYTES EXPOSED TO A 17 PSI BLAST BUT NOT A 10 PSI BLAST. FURTHER INVESTIGATION OF GENE EXPRESSION BY POLYMERASE CHAIN REACTION (PCR) ARRAY, SHOWED DYSREGULATION OF SEVERAL CYTOKINE AND CYTOKINE RECEPTORS THAT ARE INVOLVED IN NEUROINFLAMMATORY PROCESSES. WE HAVE SHOWN ABERRANT HISTONE ACETYLATION PATTERNS INVOLVED IN BLAST INDUCED ASTROGLIOSIS AND COGNITIVE IMPAIRMENTS. FURTHER UNDERSTANDING OF THEIR ROLE IN THE INJURY PROGRESSION MAY LEAD TO NOVEL THERAPEUTIC TARGETS. 2016 9 4604 24 NEGATIVE EVIDENCE FOR A FUNCTIONAL ROLE OF NEURONAL DNMT3A IN PERSISTENT PAIN. TRADITIONALLY, NEUROSCIENCE HAS HAD TO RELY ON MIXED TISSUE ANALYSIS TO EXAMINE TRANSCRIPTIONAL AND EPIGENETIC CHANGES IN THE CONTEXT OF NERVOUS SYSTEM FUNCTION OR PATHOLOGY. HOWEVER, PARTICULARLY WHEN STUDYING CHRONIC PAIN CONDITIONS, THIS APPROACH CAN BE FLAWED, SINCE IT NEGLECTS TO TAKE INTO ACCOUNT THE SHIFTING CONTRIBUTION OF DIFFERENT CELL TYPES ACROSS EXPERIMENTAL CONDITIONS. HERE, WE DEMONSTRATE THIS USING THE EXAMPLE OF DNA METHYLTRANSFERASES (DNMTS) - A GROUP OF EPIGENETIC MODIFIERS CONSISTING OF DNMT1, DNMT3A, AND DNMT3B IN MAMMALIAN CELLS. WE USED SENSORY NEURON-SPECIFIC KNOCKOUT MICE FOR DNMT3A/3B AS WELL AS PHARMACOLOGICAL BLOCKADE OF DNMT1 TO STUDY THEIR ROLE IN NOCICEPTION. IN CONTRAST TO PREVIOUS ANALYSES ON WHOLE TISSUE, WE FIND THAT DNMT3A AND 3B PROTEIN IS NOT EXPRESSED IN ADULT DRG NEURONS, THAT NONE OF THE DNA METHYLTRANSFERASES ARE REGULATED WITH INJURY AND THAT INTERFERING WITH THEIR FUNCTION HAS NO EFFECT ON NOCICEPTION. OUR RESULTS THEREFORE CURRENTLY DO NOT SUPPORT A ROLE FOR NEURONAL DNA METHYLTRANSFERASES IN PAIN PROCESSING IN ADULT ANIMALS. 2018 10 1967 25 EPIGENETIC ALTERATION OF THE DOPAMINE TRANSPORTER GENE IN ALCOHOL-DEPENDENT PATIENTS IS ASSOCIATED WITH AGE. CHRONIC ALCOHOL ABUSE AND DEPENDENCE ARE ASSOCIATED WITH DYSFUNCTIONAL DOPAMINERGIC NEUROTRANSMISSION IN MESOCORTICOLIMBIC CIRCUITS. GENETIC AND ENVIRONMENTAL FACTORS HAVE BEEN SHOWN TO MODULATE SUSCEPTIBILITY TO ALCOHOL DEPENDENCE, AND BOTH MAY ACT THROUGH EPIGENETIC MECHANISMS THAT CAN MODULATE GENE EXPRESSION, E.G. DNA METHYLATION AT CPG SITES. RECENT STUDIES HAVE SUGGESTED THAT DNA METHYLATION PATTERNS MAY CHANGE OVER TIME. HOWEVER, FEW DATA ARE AVAILABLE CONCERNING THE RATE OF THESE CHANGES IN SPECIFIC GENES. A RECENT STUDY FOUND THAT HYPERMETHYLATION OF THE PROMOTER OF THE DOPAMINE TRANSPORTER (DAT) GENE WAS POSITIVELY CORRELATED WITH ALCOHOL DEPENDENCE AND NEGATIVELY CORRELATED WITH ALCOHOL CRAVING. THE AIM OF THE PRESENT STUDY WAS TO REPLICATE THESE FINDINGS IN A LARGER SAMPLE OF ALCOHOL-DEPENDENT PATIENTS AND POPULATION-BASED CONTROLS MATCHED FOR AGE AND SEX. NO DIFFERENCE IN METHYLATION LEVEL WAS OBSERVED BETWEEN PATIENTS AND CONTROLS, AND NO DIFFERENCE IN METHYLATION LEVEL WAS OBSERVED BEFORE AND AFTER ALCOHOL WITHDRAWAL IN PATIENTS. HOWEVER, PATIENTS WITH MORE SEVERE CRAVING SHOWED A TREND TOWARDS LOWER DAT METHYLATION LEVELS (P = 0.07), WHICH IS CONSISTENT WITH PREVIOUS FINDINGS. FURTHERMORE, IN OUR OVERALL SAMPLE, DAT METHYLATION LEVELS INCREASED WITH AGE. INTERESTINGLY, A SEPARATE ANALYSIS OF PATIENTS SUGGESTED THAT THIS FINDING WAS MAINLY DRIVEN BY THE PATIENT GROUP. ALTHOUGH THE PRESENT DATA DO NOT CLARIFY WHETHER CHRONIC ALCOHOL ABUSE IS RESPONSIBLE FOR THIS PHENOMENON OR MERELY ENHANCES AN AGEING-SPECIFIC PROCESS, OUR FINDINGS SUGGEST THAT HYPERMETHYLATION IN ALCOHOL-DEPENDENT PATIENTS IS A CONSEQUENCE, RATHER THAN A CAUSE, OF THE DISORDER. 2014 11 5034 21 PHARMACOEPIGENETICS OF THE ROLE OF DNA METHYLATION IN MU-OPIOID RECEPTOR EXPRESSION IN DIFFERENT HUMAN BRAIN REGIONS. AIM: EXPOSURE TO OPIOIDS HAS BEEN ASSOCIATED WITH EPIGENETIC EFFECTS. STUDIES IN RODENTS SUGGESTED A ROLE OF VARYING DEGREES OF DNA METHYLATION IN THE DIFFERENTIAL REGULATION OF MU-OPIOID RECEPTOR EXPRESSION ACROSS THE BRAIN. METHODS: IN A TRANSLATIONAL INVESTIGATION, USING TISSUE ACQUIRED POSTMORTEM FROM 21 BRAIN REGIONS OF FORMER OPIATE ADDICTS, REPRESENTING A HUMAN COHORT WITH CHRONIC OPIOID EXPOSURE, MU-OPIOID RECEPTOR EXPRESSION WAS ANALYZED AT THE LEVEL OF DNA METHYLATION, MRNA AND PROTEIN. RESULTS & CONCLUSION: WHILE HIGH OR LOW MU-OPIOID RECEPTOR EXPRESSION SIGNIFICANTLY CORRELATED WITH LOCAL OPRM1 MRNA LEVELS, THERE WAS NO CORRESPONDING ASSOCIATION WITH OPRM1 METHYLATION STATUS. ADDITIONAL EXPERIMENTS IN HUMAN CELL LINES SHOWED THAT CHANGES IN DNA METHYLATION ASSOCIATED WITH CHANGES IN MU-OPIOID EXPRESSION WERE AN ORDER OF MAGNITUDE GREATER THAN DIFFERENCES IN BRAIN. HENCE, DIFFERENT DEGREES OF DNA METHYLATION ASSOCIATED WITH CHRONIC OPIOID EXPOSURE ARE UNLIKELY TO EXERT A MAJOR ROLE IN THE REGION-SPECIFICITY OF MU-OPIOID RECEPTOR EXPRESSION IN THE HUMAN BRAIN. 2016 12 4628 24 NEUROEPIGENETIC ALTERATIONS IN THE PREFRONTAL CORTEX OF TYPE 2 DIABETIC MICE THROUGH DNA HYPERMETHYLATION. BACKGROUND: DNA METHYLATION CHANGES HAVE KNOWN TO DOWNREGULATE SEVERAL REGULATORY PROTEINS EPIGENETICALLY DURING VARIOUS NEURODEGENERATIVE DISORDERS. OUR STUDY AIMS TO UNDERSTAND THE EFFECT OF THIS GLOBAL DNA METHYLATION ON THE CEREBRAL COMPLICATIONS OF TYPE 2 DIABETES MICE, AND ITS NOTABLE EFFECT ON MAINTAINING THE SYNAPTIC FIDELITY. METHODS AND RESULTS: CHRONIC HIGH FAT DIET AND STREPTOZOTOCIN-INDUCED DIABETIC MICE WERE STUDIED FOR THE NEUROBEHAVIORAL AND NEUROANATOMIC PARAMETERS PERTAINING TO PREFRONTAL CORTEX, SUBSEQUENTLY ELUCIDATING THE ASSOCIATED CHANGES IN DNA METHYLATION WITHIN THESE DIABETIC BRAINS. FURTHER, THE IMPACT OF THIS EPIGENETIC DYSREGULATION ON HSF1, BDNF AND PSD95 WERE STUDIED BY ASSESSING THE BINDING AFFINITY AND LEVEL OF % METHYLATION WITHIN THE PROMOTER SITE OF THEIR RESPECTIVE GENES. OUR STUDY SUGGEST INCREASED DNMT ABERRATIONS WITHIN THE PREFRONTAL CORTEX, WITH INCREASED MECP2 LEVELS, CONFIRMING DNA HYPERMETHYLATION. THIS WAS IN ACCORDANCE WITH THE ALTERED NEUROBEHAVIORAL CHANGES. FURTHER, THE HYPERMETHYLATION WAS FOUND TO PARTICIPATE IN GENE SILENCING OF HSF1, BDNF AND PSD95 PROTEINS, RESPONSIBLE FOR MAINTAINING THE SYNAPTIC FIDELITY. CONCLUSION: OVERALL, OUR STUDY CONCLUDES THE PLAUSIBLE INVOLVEMENT OF NEUROEPIGENETIC ALTERATIONS IN THE PREFRONTAL CORTEX (PFC) OF THE TYPE 2 DIABETES MICE, SPECIFICALLY DNA HYPERMETHYLATION. PFC PLAYS A CENTRAL ROLE IN MODULATING COGNITIVE AND OTHER EXECUTIVE FUNCTIONS THROUGH ITS CONNECTION WITH SEVERAL BRAIN REGIONS, AND THUS THERAPEUTIC STRATEGIES TARGETING EPIGENETIC MODULATIONS IN IT, CAN PAVE A WAY IN CONTROLLING SEVERAL NEUROLOGICAL ALTERATIONS IN THE BRAIN. 2022 13 377 27 AN EPIGENETIC HYPOTHESIS FOR THE GENOMIC MEMORY OF PAIN. CHRONIC PAIN IS ACCOMPANIED WITH LONG-TERM SENSORY, AFFECTIVE AND COGNITIVE DISTURBANCES. WHAT ARE THE MECHANISMS THAT MEDIATE THE LONG-TERM CONSEQUENCES OF PAINFUL EXPERIENCES AND EMBED THEM IN THE GENOME? WE HYPOTHESIZE THAT ALTERATIONS IN DNA METHYLATION, AN ENZYMATIC COVALENT MODIFICATION OF CYTOSINE BASES IN DNA, SERVE AS A "GENOMIC" MEMORY OF PAIN IN THE ADULT CORTEX. DNA METHYLATION IS AN EPIGENETIC MECHANISM FOR LONG-TERM REGULATION OF GENE EXPRESSION. NEURONAL PLASTICITY AT THE NEUROANATOMICAL, FUNCTIONAL, MORPHOLOGICAL, PHYSIOLOGICAL AND MOLECULAR LEVELS HAS BEEN DEMONSTRATED THROUGHOUT THE NEUROAXIS IN RESPONSE TO PERSISTENT PAIN, INCLUDING IN THE ADULT PREFRONTAL CORTEX (PFC). WE HAVE PREVIOUSLY REPORTED WIDESPREAD CHANGES IN GENE EXPRESSION AND DNA METHYLATION IN THE PFC MANY MONTHS FOLLOWING PERIPHERAL NERVE INJURY. IN SUPPORT OF THIS HYPOTHESIS, WE SHOW HERE THAT UP-REGULATION OF A GENE INVOLVED WITH SYNAPTIC FUNCTION, SYNAPTOTAGMIN II (SYT2), IN THE PFC IN A CHRONIC PAIN MODEL IS ASSOCIATED WITH LONG-TERM CHANGES IN DNA METHYLATION. THE CHALLENGES OF UNDERSTANDING THE CONTRIBUTIONS OF EPIGENETIC MECHANISMS SUCH AS DNA METHYLATION WITHIN THE PFC TO PAIN CHRONICITY AND THEIR THERAPEUTIC IMPLICATIONS ARE DISCUSSED. 2015 14 2297 20 EPIGENETIC REGULATION OF ACUTE INFLAMMATORY PAIN. ACUTE PAIN IS ASSOCIATED WITH TISSUE DAMAGE, WHICH RESULTS IN THE RELEASE OF INFLAMMATORY MEDIATORS. RECENT STUDIES POINT TO THE INVOLVEMENT OF EPIGENETIC MECHANISMS (DNA METHYLATION) IN THE DEVELOPMENT OF PAIN. WE HAVE FOUND THAT DURING ACUTE INFLAMMATORY PAIN INDUCED BY THE APPLICATION OF 10% MUSTARD OIL ON THE TONGUES OF RATS, LEVELS OF DNMT3A AND 3B WERE ELEVATED MARKEDLY (36 AND 42 % RESPECTIVELY), WHEREAS THE LEVEL OF DNMT1 WAS NOT CHANGED SIGNIFICANTLY. PREVIOUS INJECTION OF XEFOCAM WITH 0,4 MG/KG DOSE DECREASED LEVELS OF DNMT3A AND 3B (25 AND 24% RESPECTIVELY). THE LEVEL OF DNMT1 WAS NOT CHANGED SIGNIFICANTLY COMPARED TO THE CONTROL GROUP. THE FINDINGS SUPPORT THE IDEA THAT INHIBITORS OF DNA-METHYLTRANSFERASES COULD BE USEFUL FOR PAIN MANAGEMENT. OUR DATA SUGGEST THAT NSAIDS (ALONE OR IN COMBINATION WITH DNMT INHIBITORS) MAY BE PROPOSED AS POSSIBLE EPIGENETIC REGULATORY AGENTS, WHICH MAY PLAY A ROLE IN EPIGENETIC MECHANISMS INDIRECTLY THROUGH ALTERING THE ACTIVITY OF INFLAMMATORY MEDIATORS INVOLVED IN PAIN DEVELOPMENT. 2014 15 3077 31 GENOME-WIDE METHYL-SEQ ANALYSIS OF BLOOD-BRAIN TARGETS OF GLUCOCORTICOID EXPOSURE. CHRONIC EXPOSURE TO GLUCOCORTICOIDS (GCS) CAN LEAD TO PSYCHIATRIC COMPLICATIONS THROUGH EPIGENETIC MECHANISMS SUCH AS DNA METHYLATION (DNAM). WE SOUGHT TO DETERMINE WHETHER EPIGENETIC CHANGES IN A PERIPHERAL TISSUE CAN SERVE AS A SURROGATE FOR THOSE IN A RELATIVELY INACCESSIBLE TISSUE SUCH AS THE BRAIN. DNA EXTRACTED FROM THE HIPPOCAMPUS AND BLOOD OF MICE TREATED WITH GCS OR VEHICLE SOLUTION WAS ASSAYED USING A GENOME-WIDE DNAM PLATFORM (METHYL-SEQ) TO IDENTIFY DIFFERENTIALLY METHYLATED REGIONS (DMRS) INDUCED BY GC TREATMENT. WE OBSERVED THAT APPROXIMATELY 70% OF THE DMRS IN BOTH TISSUES LOST METHYLATION FOLLOWING GC TREATMENT. OF THE 3,095 DMRS THAT MAPPED TO THE SAME GENES IN BOTH TISSUES, 1,853 DMRS UNDERWENT DNAM CHANGES IN THE SAME DIRECTION. INTERESTINGLY, ONLY 209 DMRS (<7%) OVERLAPPED IN GENOMIC COORDINATES BETWEEN THE 2 TISSUES, SUGGESTING TISSUE-SPECIFIC DIFFERENCES IN GC-TARGETED LOCI. PATHWAY ANALYSIS SHOWED THAT THE DMR-ASSOCIATED GENES WERE MEMBERS OF PATHWAYS INVOLVED IN METABOLISM, IMMUNE FUNCTION, AND NEURODEVELOPMENT. ALSO, CHANGES IN CELL TYPE COMPOSITION OF BLOOD AND BRAIN WERE EXAMINED BY FLUORESCENCE-ACTIVATED CELL SORTING. SEPARATION OF THE CORTEX INTO NEURONAL AND NON-NEURONAL FRACTIONS AND THE LEUKOCYTES INTO T-CELLS, B-CELLS, AND NEUTROPHILS SHOWED THAT GC-INDUCED METHYLATION CHANGES PRIMARILY OCCURRED IN NEURONS AND T-CELLS, WITH THE BLOOD TISSUE ALSO UNDERGOING A SHIFT IN THE PROPORTION OF CONSTITUENT CELL TYPES WHILE THE PROPORTION OF NEURONS AND GLIA IN THE BRAIN REMAINED STABLE. FROM THE CURRENT PILOT STUDY, WE FOUND THAT DESPITE TISSUE-SPECIFIC EPIGENETIC CHANGES AND CELLULAR HETEROGENEITY, BLOOD CAN SERVE AS A SURROGATE FOR GC-INDUCED CHANGES IN THE BRAIN. 2017 16 5006 35 PERIPHERAL NERVE INJURY IS ACCOMPANIED BY CHRONIC TRANSCRIPTOME-WIDE CHANGES IN THE MOUSE PREFRONTAL CORTEX. BACKGROUND: PERIPHERAL NERVE INJURY CAN HAVE LONG-TERM CONSEQUENCES INCLUDING PAIN-RELATED MANIFESTATIONS, SUCH AS HYPERSENSITIVITY TO CUTANEOUS STIMULI, AS WELL AS AFFECTIVE AND COGNITIVE DISTURBANCES, SUGGESTING THE INVOLVEMENT OF SUPRASPINAL MECHANISMS. CHANGES IN BRAIN STRUCTURE AND CORTICAL FUNCTION ASSOCIATED WITH MANY CHRONIC PAIN CONDITIONS HAVE BEEN REPORTED IN THE PREFRONTAL CORTEX (PFC). THE PFC IS IMPLICATED IN PAIN-RELATED CO-MORBIDITIES SUCH AS DEPRESSION, ANXIETY AND IMPAIRED EMOTIONAL DECISION-MAKING ABILITY. WE RECENTLY REPORTED THAT THIS REGION IS SUBJECT TO SIGNIFICANT EPIGENETIC REPROGRAMMING FOLLOWING PERIPHERAL NERVE INJURY, AND NORMALIZATION OF PAIN-RELATED STRUCTURAL, FUNCTIONAL AND EPIGENETIC ABNORMALITIES IN THE PFC ARE ALL ASSOCIATED WITH EFFECTIVE PAIN REDUCTION. IN THIS STUDY, WE USED THE SPARED NERVE INJURY (SNI) MODEL OF NEUROPATHIC PAIN TO TEST THE HYPOTHESIS THAT PERIPHERAL NERVE INJURY TRIGGERS PERSISTENT LONG-LASTING CHANGES IN GENE EXPRESSION IN THE PFC, WHICH ALTER FUNCTIONAL GENE NETWORKS, THUS PROVIDING A POSSIBLE EXPLANATION FOR CHRONIC PAIN ASSOCIATED BEHAVIORS. RESULTS: SNI OR SHAM SURGERY WHERE PERFORMED IN MALE CD1 MICE AT THREE MONTHS OF AGE. SIX MONTHS AFTER INJURY, WE PERFORMED TRANSCRIPTOME-WIDE SEQUENCING (RNASEQ), WHICH REVEALED 1147 DIFFERENTIALLY REGULATED TRANSCRIPTS IN THE PFC IN NERVE-INJURED VS. CONTROL MICE. CHANGES IN GENE EXPRESSION OCCURRED ACROSS A NUMBER OF FUNCTIONAL GENE CLUSTERS ENCODING CARDINAL BIOLOGICAL PROCESSES AS REVEALED BY INGENUITY PATHWAY ANALYSIS. SIGNIFICANTLY ALTERED BIOLOGICAL PROCESSES INCLUDED NEUROLOGICAL DISEASE, SKELETAL MUSCULAR DISORDERS, BEHAVIOR, AND PSYCHOLOGICAL DISORDERS. SEVERAL OF THE CHANGES DETECTED BY RNASEQ WERE VALIDATED BY RT-QPCR AND INCLUDED TRANSCRIPTS WITH KNOWN ROLES IN CHRONIC PAIN AND/OR NEURONAL PLASTICITY INCLUDING THE NMDA RECEPTOR (GLUTAMATE RECEPTOR, IONOTROPIC, NMDA; GRIN1), NEURITE OUTGROWTH (ROUNDABOUT 3; ROBO3), GLIOSIS (GLIAL FIBRILLARY ACIDIC PROTEIN; GFAP), VESICULAR RELEASE (SYNAPTOTAGMIN 2; SYT2), AND NEURONAL EXCITABILITY (VOLTAGE-GATED SODIUM CHANNEL, TYPE I; SCN1A). CONCLUSIONS: THIS STUDY USED AN UNBIASED APPROACH TO DOCUMENT LONG-TERM ALTERATIONS IN GENE EXPRESSION IN THE BRAIN FOLLOWING PERIPHERAL NERVE INJURY. WE PROPOSE THAT THESE CHANGES ARE MAINTAINED AS A MEMORY OF AN INSULT THAT IS TEMPORALLY AND SPATIALLY DISTANT FROM THE INITIAL INJURY. 2013 17 3080 28 GENOME-WIDE METHYLATION IN ALCOHOL USE DISORDER SUBJECTS: IMPLICATIONS FOR AN EPIGENETIC REGULATION OF THE CORTICO-LIMBIC GLUCOCORTICOID RECEPTORS (NR3C1). ENVIRONMENTAL FACTORS, INCLUDING SUBSTANCE ABUSE AND STRESS, CAUSE LONG-LASTING CHANGES IN THE REGULATION OF GENE EXPRESSION IN THE BRAIN VIA EPIGENETIC MECHANISMS, SUCH AS DNA METHYLATION. WE EXAMINED GENOME-WIDE DNA METHYLATION PATTERNS IN THE PREFRONTAL CORTEX (PFC, BA10) OF 25 PAIRS OF CONTROL AND INDIVIDUALS WITH ALCOHOL USE DISORDER (AUD), USING THE INFINIUM((R)) METHYLATIONEPIC BEADCHIP. WE IDENTIFIED 5254 DIFFERENTIALLY METHYLATED CPGS (P(NOMINAL) < 0.005). BIOINFORMATIC ANALYSES HIGHLIGHTED BIOLOGICAL PROCESSES CONTAINING GENES RELATED TO STRESS ADAPTATION, INCLUDING THE GLUCOCORTICOID RECEPTOR (ENCODED BY NR3C1). CONSIDERING THAT ALCOHOL IS A STRESSOR, WE FOCUSED OUR ATTENTION ON DIFFERENTIALLY METHYLATED REGIONS OF THE NR3C1 GENE AND VALIDATED THE DIFFERENTIAL METHYLATION OF SEVERAL GENES IN THE NR3C1 NETWORK. CHRONIC ALCOHOL DRINKING RESULTS IN A SIGNIFICANT INCREASED METHYLATION OF THE NR3C1 EXON VARIANT 1(H), WITH A PARTICULAR INCREASE IN THE LEVELS OF 5-HYDROXYMETHYLCYTOSINE OVER 5-METHYLCYTOSINE. THESE CHANGES IN DNA METHYLATION WERE ASSOCIATED WITH REDUCED NR3C1 MRNA AND PROTEIN EXPRESSION LEVELS IN PFC, AS WELL AS OTHER CORTICO-LIMBIC REGIONS OF AUD SUBJECTS WHEN COMPARED WITH CONTROLS. FURTHERMORE, WE SHOW THAT THE EXPRESSION OF SEVERAL STRESS-RESPONSIVE GENES (E.G., CRF, POMC, AND FKBP5) IS ALTERED IN THE PFC OF AUD SUBJECTS. THESE STRESS-RESPONSE GENES WERE ALSO CHANGED IN THE HIPPOCAMPUS, A REGION THAT IS HIGHLY SUSCEPTIBLE TO STRESS. THESE DATA SUGGEST THAT ALCOHOL-DEPENDENT ABERRANT DNA METHYLATION OF NR3C1 AND CONSEQUENT CHANGES IN OTHER STRESS-RELATED GENES MIGHT BE FUNDAMENTAL IN THE PATHOPHYSIOLOGY OF AUD AND LAY THE GROUNDWORK FOR TREATMENTS TARGETING THE EPIGENETIC MECHANISMS REGULATING NR3C1 IN AUD. 2021 18 1301 26 DEEP SEQUENCING REVEALS INCREASED DNA METHYLATION IN CHRONIC RAT EPILEPSY. EPILEPSY IS A FREQUENT NEUROLOGICAL DISORDER, ALTHOUGH ONSET AND PROGRESSION OF SEIZURES REMAIN DIFFICULT TO PREDICT IN AFFECTED PATIENTS, IRRESPECTIVE OF THEIR EPILEPTOGENIC CONDITION. PREVIOUS STUDIES IN ANIMAL MODELS AS WELL AS HUMAN EPILEPTIC BRAIN TISSUE REVEALED A REMARKABLY DIVERSE PATTERN OF GENE EXPRESSION IMPLICATING EPIGENETIC CHANGES TO CONTRIBUTE TO DISEASE PROGRESSION. HERE WE MAPPED FOR THE FIRST TIME GLOBAL DNA METHYLATION PATTERNS IN CHRONIC EPILEPTIC RATS AND CONTROLS. USING METHYL-CPG CAPTURE ASSOCIATED WITH MASSIVE PARALLEL SEQUENCING (METHYL-SEQ) WE REPORT THE GENOMIC METHYLATION SIGNATURE OF THE CHRONIC EPILEPTIC STATE. WE OBSERVED A PREDOMINANT INCREASE, RATHER THAN LOSS OF DNA METHYLATION IN CHRONIC RAT EPILEPSY. ABERRANT METHYLATION PATTERNS WERE INVERSELY CORRELATED WITH GENE EXPRESSION CHANGES USING MRNA SEQUENCING FROM SAME ANIMALS AND TISSUE SPECIMENS. ADMINISTRATION OF A KETOGENIC, HIGH-FAT, LOW-CARBOHYDRATE DIET ATTENUATED SEIZURE PROGRESSION AND AMELIORATED DNA METHYLATION MEDIATED CHANGES IN GENE EXPRESSION. THIS IS THE FIRST REPORT OF UNSUPERVISED CLUSTERING OF AN EPIGENETIC MARK BEING USED IN EPILEPSY RESEARCH TO SEPARATE EPILEPTIC FROM NON-EPILEPTIC ANIMALS AS WELL AS FROM ANIMALS RECEIVING ANTI-CONVULSIVE DIETARY TREATMENT. WE FURTHER DISCUSS THE POTENTIAL IMPACT OF EPIGENETIC CHANGES AS A PATHOGENIC MECHANISM OF EPILEPTOGENESIS. 2013 19 4093 21 MATERNAL SEPARATION FOLLOWED BY CHRONIC MILD STRESS IN ADULTHOOD IS ASSOCIATED WITH CONCERTED EPIGENETIC REGULATION OF AP-1 COMPLEX GENES. DEPRESSION IS ONE OF THE MOST PREVALENT MENTAL DISEASES WORLDWIDE. PATIENTS WITH PSYCHIATRIC DISEASES OFTEN HAVE A HISTORY OF CHILDHOOD NEGLECT, INDICATING THAT EARLY-LIFE EXPERIENCES PREDISPOSE TO PSYCHIATRIC DISEASES IN ADULTHOOD. TWO STRONG MODELS WERE USED IN THE PRESENT STUDY: THE MATERNAL SEPARATION/EARLY DEPRIVATION MODEL (MS) AND THE CHRONIC MILD STRESS MODEL (CMS). IN BOTH MODELS, WE FOUND CHANGES IN THE EXPRESSION OF A NUMBER OF GENES SUCH AS CREB AND NPY. STRIKINGLY, THERE WAS A CLEAR REGULATION OF EXPRESSION OF FOUR GENES INVOLVED IN THE AP-1 COMPLEX: C-FOS, C-JUN, FOSB, AND JUN-B. INTERESTINGLY, DIFFERENT EXPRESSION LEVELS WERE OBSERVED DEPENDING ON THE MODEL, WHEREAS THE COMBINATION OF THE MODELS RESULTED IN A NORMAL LEVEL OF GENE EXPRESSION. THE EFFECTS OF MS AND CMS ON GENE EXPRESSION WERE ASSOCIATED WITH DISTINCT HISTONE METHYLATION/ACETYLATION PATTERNS OF ALL FOUR GENES. THE EPIGENETIC CHANGES, LIKE GENE EXPRESSION, WERE ALSO DEPENDENT ON THE SPECIFIC STRESSOR OR THEIR COMBINATION. THE OBTAINED RESULTS SUGGEST THAT SINGLE LIFE EVENTS LEAVE A MARK ON GENE EXPRESSION AND THE EPIGENETIC SIGNATURE OF GENE PROMOTERS, BUT A COMBINATION OF DIFFERENT STRESSORS AT DIFFERENT LIFE STAGES CAN FURTHER CHANGE GENE EXPRESSION THROUGH EPIGENETIC FACTORS, POSSIBLY CAUSING THE LONG-LASTING ADVERSE EFFECTS OF STRESS. 2021 20 345 31 ALTERED BRAIN EXPRESSION OF DNA METHYLATION AND HYDROXYMETHYLATION EPIGENETIC ENZYMES IN A RAT MODEL OF NEUROPATHIC PAIN. THE ROLE OF EPIGENETICS IN CHRONIC PAIN AT THE SUPRASPINAL LEVEL IS YET TO BE FULLY CHARACTERIZED. DNA HISTONE METHYLATION IS CRUCIALLY REGULATED BY DE NOVO METHYLTRANSFERASES (DNMT1-3) AND TEN-ELEVEN TRANSLOCATION DIOXYGENASES (TET1-3). EVIDENCE HAS SHOWN THAT METHYLATION MARKERS ARE ALTERED IN DIFFERENT CNS REGIONS RELATED TO NOCICEPTION, NAMELY THE DORSAL ROOT GANGLIA, THE SPINAL CORD, AND DIFFERENT BRAIN AREAS. DECREASED GLOBAL METHYLATION WAS FOUND IN THE DRG, THE PREFRONTAL CORTEX, AND THE AMYGDALA, WHICH WAS ASSOCIATED WITH DECREASED DNMT1/3A EXPRESSION. IN CONTRAST, INCREASED METHYLATION LEVELS AND MRNA LEVELS OF TET1 AND TET3 WERE LINKED TO AUGMENTED PAIN HYPERSENSITIVITY AND ALLODYNIA IN INFLAMMATORY AND NEUROPATHIC PAIN MODELS. SINCE EPIGENETIC MECHANISMS MAY BE RESPONSIBLE FOR THE REGULATION AND COORDINATION OF VARIOUS TRANSCRIPTIONAL MODIFICATIONS DESCRIBED IN CHRONIC PAIN STATES, WITH THIS STUDY, WE AIMED TO EVALUATE THE FUNCTIONAL ROLE OF TET1-3 AND DNMT1/3A GENES IN NEUROPATHIC PAIN IN SEVERAL BRAIN AREAS. IN A SPARED NERVE INJURY RAT MODEL OF NEUROPATHIC PAIN, 21 DAYS AFTER SURGERY, WE FOUND INCREASED TET1 EXPRESSION IN THE MEDIAL PREFRONTAL CORTEX AND DECREASED EXPRESSION IN THE CAUDATE-PUTAMEN AND THE AMYGDALA; TET2 WAS UPREGULATED IN THE MEDIAL THALAMUS; TET3 MRNA LEVELS WERE REDUCED IN THE MEDIAL PREFRONTAL CORTEX AND THE CAUDATE-PUTAMEN; AND DNMT1 WAS DOWNREGULATED IN THE CAUDATE-PUTAMEN AND THE MEDIAL THALAMUS. NO STATISTICALLY SIGNIFICANT CHANGES IN EXPRESSION WERE OBSERVED WITH DNMT3A. OUR RESULTS SUGGEST A COMPLEX FUNCTIONAL ROLE FOR THESE GENES IN DIFFERENT BRAIN AREAS IN THE CONTEXT OF NEUROPATHIC PAIN. THE NOTION OF DNA METHYLATION AND HYDROXYMETHYLATION BEING CELL-TYPE SPECIFIC AND NOT TISSUE SPECIFIC, AS WELL AS THE POSSIBILITY OF CHRONOLOGICALLY DIFFERENTIAL GENE EXPRESSION AFTER THE ESTABLISHMENT OF NEUROPATHIC OR INFLAMMATORY PAIN MODELS, OUGHT TO BE ADDRESSED IN FUTURE STUDIES. 2023