1 2571 84 EPIGENETICS OF CHRONIC PAIN AFTER THORACIC SURGERY. PURPOSE OF REVIEW: CHRONIC PAIN AFTER SURGERY IS A MAJOR PUBLIC HEALTH PROBLEM AND A MAJOR CONCERN FOR PERIOPERATIVE PHYSICIANS. THORACIC SURGERY PRESENTS A UNIQUE CHALLENGE, AS THORACOTOMY IS AMONG THE HIGHEST RISK SURGERIES TO DEVELOP PERSISTENT POSTSURGICAL PAIN. THE PURPOSE OF THIS REVIEW IS TO DISCUSS THE RELEVANCE OF RESEARCH IN PAIN EPIGENETICS TO PATIENTS WITH PERSISTENT PAIN AFTER THORACIC SURGERY. RECENT FINDINGS: RECENT ADVANCES HAVE LINKED CHRONIC PAIN STATES TO GENETIC AND EPIGENETIC CHANGES. PROGRESS IN OUR UNDERSTANDING OF CHRONIC PAIN HAS HIGHLIGHTED THE IMPORTANCE OF IMMUNE MODULATION OF PAIN. IT IS POSSIBLE THAT EPIGENETIC CHANGES DRIVING CHRONIC PAIN OCCUR IN THE PERIOPERATIVE SETTING VIA HISTONE MODIFICATION AND DNA METHYLATION. SUMMARY: THE TRANSITION FROM ACUTE TO CHRONIC PAIN AFTER THORACIC SURGERY MAY BE MEDIATED BY EPIGENETICS. HERE, WE DISCUSS EPIGENETIC MODIFICATIONS THAT HAVE BEEN DISCOVERED IN ANIMAL MODELS OF CHRONIC PAIN THAT MAY PREDISPOSE PATIENTS TO PERSISTENT NEUROPATHIC PAIN AFTER THORACIC SURGERY. 2014 2 1509 20 DNA METHYLATION AND NON-CODING RNAS DURING TISSUE-INJURY ASSOCIATED PAIN. WHILE ABOUT HALF OF THE POPULATION EXPERIENCE PERSISTENT PAIN ASSOCIATED WITH TISSUE DAMAGES DURING THEIR LIFETIME, CURRENT SYMPTOM-BASED APPROACHES OFTEN FAIL TO REDUCE SUCH PAIN TO A SATISFACTORY LEVEL. TO PROVIDE BETTER PATIENT CARE, MECHANISM-BASED ANALGESIC APPROACHES MUST BE DEVELOPED, WHICH NECESSITATES A COMPREHENSIVE UNDERSTANDING OF THE NOCICEPTIVE MECHANISM LEADING TO TISSUE INJURY-ASSOCIATED PERSISTENT PAIN. EPIGENETIC EVENTS LEADING THE ALTERED TRANSCRIPTION IN THE NERVOUS SYSTEM ARE PIVOTAL IN THE MAINTENANCE OF PAIN IN TISSUE INJURY. HOWEVER, THE MECHANISMS THROUGH WHICH THOSE EVENTS CONTRIBUTE TO THE PERSISTENCE OF PAIN ARE NOT FULLY UNDERSTOOD. THIS REVIEW PROVIDES A SUMMARY AND CRITICAL EVALUATION OF TWO EPIGENETIC MECHANISMS, DNA METHYLATION AND NON-CODING RNA EXPRESSION, ON TRANSCRIPTIONAL MODULATION IN NOCICEPTIVE PATHWAYS DURING THE DEVELOPMENT OF TISSUE INJURY-ASSOCIATED PAIN. WE ASSESS THE PRE-CLINICAL DATA AND THEIR TRANSLATIONAL IMPLICATION AND EVALUATE THE POTENTIAL OF CONTROLLING DNA METHYLATION AND NON-CODING RNA EXPRESSION AS NOVEL ANALGESIC APPROACHES AND/OR BIOMARKERS OF PERSISTENT PAIN. 2022 3 5926 35 TARGETING EPIGENETIC MECHANISMS FOR CHRONIC PAIN: A VALID APPROACH FOR THE DEVELOPMENT OF NOVEL THERAPEUTICS. CHRONIC PAIN IS A MULTIFACETED AND COMPLEX CONDITION. BROADLY CLASSIFIED INTO SOMATIC, VISCERAL, OR NEUROPATHIC PAIN, IT IS POORLY MANAGED DESPITE ITS PREVALENCE. CURRENT DRUGS USED FOR THE TREATMENT OF CHRONIC PAIN ARE LIMITED BY TOLERANCE WITH LONG-TERM USE, ABUSE POTENTIAL, AND MULTIPLE ADVERSE SIDE EFFECTS. THE PERSISTENT NATURE OF PAIN SUGGESTS THAT EPIGENETIC MACHINERY MAY BE A CRITICAL FACTOR DRIVING CHRONIC PAIN. IN THIS REVIEW, WE DISCUSS THE LATEST INSIGHTS INTO EPIGENETIC PROCESSES, INCLUDING DNA METHYLATION, HISTONE MODIFICATIONS, AND MICRORNAS, AND WE DESCRIBE THEIR INVOLVEMENT IN THE PATHOPHYSIOLOGY OF CHRONIC PAIN AND WHETHER EPIGENETIC MODIFICATIONS COULD BE APPLIED AS FUTURE THERAPEUTIC TARGETS FOR CHRONIC PAIN. WE PROVIDE EVIDENCE FROM EXPERIMENTAL MODELS AND TRANSLATIONAL RESEARCH IN HUMAN TISSUE THAT HAVE ENHANCED OUR UNDERSTANDING OF EPIGENETIC PROCESSES MEDIATING NOCICEPTION, AND WE THEN SPECULATE ON THE POTENTIAL FUTURE USE OF MORE SPECIFIC AND SELECTIVE AGENTS THAT TARGET EPIGENETIC MECHANISMS TO ATTENUATE PAIN. 2016 4 5928 22 TARGETING EPIGENETIC MECHANISMS FOR PAIN RELIEF. EPIGENETIC CHANGES ARE CHEMICAL MODIFICATIONS TO CHROMATIN THAT MODULATE GENE ACTIVITY WITHOUT ALTERING THE DNA SEQUENCE. WHILE RESEARCH ON EPIGENETICS HAS GROWN EXPONENTIALLY OVER THE PAST FEW YEARS, VERY FEW STUDIES HAVE INVESTIGATED EPIGENETIC MECHANISMS IN RELATION TO PAIN STATES. HOWEVER, EPIGENETIC MECHANISMS ARE CRUCIAL TO MEMORY FORMATION THAT REQUIRES SIMILAR SYNAPTIC PLASTICITY TO PAIN PROCESSING, INDICATING THAT THEY MAY PLAY A KEY ROLE IN THE CONTROL OF PAIN STATES. THIS ARTICLE REVIEWS THE EARLY EVIDENCE SUGGESTING THAT EPIGENETIC MECHANISMS ARE ENGAGED AFTER INJURY AND IN CHRONIC PAIN STATES, AND THAT DRUGS USED CLINICALLY TO TARGET THE EPIGENETIC MACHINERY FOR THE TREATMENT OF CANCER MIGHT BE USEFUL FOR THE MANAGEMENT OF CHRONIC PAIN. 2012 5 6124 27 THE EPIGENETIC MECHANISMS INVOLVED IN CHRONIC PAIN IN RODENTS: A MINI- REVIEW. CHRONIC PAIN IS A COMMON DISTRESSING NEUROLOGICAL DISORDER AND ABOUT 30% OF THE GLOBAL POPULATION SUFFERS FROM IT. IN ADDITION TO BEING HIGHLY PREVALENT, CHRONIC PAIN CAUSES A HEAVY ECONOMIC AND SOCIAL BURDEN. ALTHOUGH SUBSTANTIAL PROGRESS HAS BEEN ACHIEVED TO DISSECT THE UNDERLYING MECHANISM OF CHRONIC PAIN IN THE PAST FEW DECADES, THE INCIDENCE AND TREATMENT OF THIS NEUROLOGICAL ILLNESS IS YET NOT PROPERLY MANAGED IN CLINICAL PRACTICE. WHILE NERVE INJURY-, CHEMOTHERAPY- OR INFLAMMATION-INDUCED FUNCTIONAL REGULATION OF GENE EXPRESSION IN THE DORSAL ROOT GANGLION AND SPINAL CORD ARE EXTENSIVELY REPORTED TO BE INVOLVED IN THE PATHOGENIC PROCESS OF CHRONIC PAIN, THE SPECIFIC MECHANISM OF THESE ALTERED TRANSCRIPTIONAL PROFILE STILL REMAINS UNCLEAR. RECENT STUDIES HAVE SHOWN THAT EPIGENETIC MECHANISMS, INCLUDING DNA/RNA METHYLATION, HISTONE MODIFICATION AND CIRCULAR RNAS REGULATION, ARE INVOLVED IN THE OCCURRENCE AND DEVELOPMENT OF CHRONIC PAIN. IN THIS REVIEW, WE PROVIDE A DESCRIPTION OF RESEARCH ON THE ROLE OF EPIGENETIC MECHANISM IN CHRONIC PAIN, SUMMARIZE THE LATEST CLINICAL AND PRECLINICAL ADVANCE IN THIS FIELD, AND PROPOSE THE POTENTIAL DIRECTIONS FOR FURTHER RESEARCH TO ELUCIDATE THE MOLECULAR MECHANISM UNDERLYING THE PATHOGENESIS OF CHRONIC PAIN. 2022 6 2523 34 EPIGENETICS AND THE TRANSITION FROM ACUTE TO CHRONIC PAIN. OBJECTIVE: THE OBJECTIVE OF THIS STUDY WAS TO REVIEW THE EPIGENETIC MODIFICATIONS INVOLVED IN THE TRANSITION FROM ACUTE TO CHRONIC PAIN AND TO IDENTIFY POTENTIAL TARGETS FOR THE DEVELOPMENT OF NOVEL, INDIVIDUALIZED PAIN THERAPEUTICS. BACKGROUND: EPIGENETICS IS THE STUDY OF HERITABLE MODIFICATIONS IN GENE EXPRESSION AND PHENOTYPE THAT DO NOT REQUIRE A CHANGE IN GENETIC SEQUENCE TO MANIFEST THEIR EFFECTS. ENVIRONMENTAL TOXINS, MEDICATIONS, DIET, AND PSYCHOLOGICAL STRESSES CAN ALTER EPIGENETIC PROCESSES SUCH AS DNA METHYLATION, HISTONE ACETYLATION, AND RNA INTERFERENCE. AS EPIGENETIC MODIFICATIONS POTENTIALLY PLAY AN IMPORTANT ROLE IN INFLAMMATORY CYTOKINE METABOLISM, STEROID RESPONSIVENESS, AND OPIOID SENSITIVITY, THEY ARE LIKELY KEY FACTORS IN THE DEVELOPMENT OF CHRONIC PAIN. ALTHOUGH OUR KNOWLEDGE OF THE HUMAN GENETIC CODE AND DISEASE-ASSOCIATED POLYMORPHISMS HAS GROWN SIGNIFICANTLY IN THE PAST DECADE, WE HAVE NOT YET BEEN ABLE TO ELUCIDATE THE MECHANISMS THAT LEAD TO THE DEVELOPMENT OF PERSISTENT PAIN AFTER NERVE INJURY OR SURGERY. DESIGN: THIS IS A FOCUSED LITERATURE REVIEW OF EPIGENETIC SCIENCE AND ITS RELATIONSHIP TO CHRONIC PAIN. RESULTS: SIGNIFICANT LABORATORY AND CLINICAL DATA SUPPORT THE NOTION THAT EPIGENETIC MODIFICATIONS ARE AFFECTED BY THE ENVIRONMENT AND LEAD TO DIFFERENTIAL GENE EXPRESSION. SIMILAR TO MECHANISMS INVOLVED IN THE DEVELOPMENT OF CANCER, NEURODEGENERATIVE DISEASE, AND INFLAMMATORY DISORDERS, THE LITERATURE ENDORSES AN IMPORTANT POTENTIAL ROLE FOR EPIGENETICS IN CHRONIC PAIN. CONCLUSIONS: EPIGENETIC ANALYSIS MAY IDENTIFY MECHANISMS CRITICAL TO THE DEVELOPMENT OF CHRONIC PAIN AFTER INJURY, AND MAY PROVIDE NEW PATHWAYS AND TARGET MECHANISMS FOR FUTURE DRUG DEVELOPMENT AND INDIVIDUALIZED MEDICINE. 2012 7 2611 27 EPIGENETICS: A PROMISING PARADIGM FOR BETTER UNDERSTANDING AND MANAGING PAIN. EPIGENETIC REGULATION OF GENE EXPRESSION IS A RAPIDLY GROWING AREA OF RESEARCH. CONSIDERING THE LONGEVITY AND PLASTICITY OF NEURONS, THE STUDIES ON EPIGENETIC PATHWAYS IN THE NERVOUS SYSTEM SHOULD BE OF SPECIAL INTEREST FOR BOTH EPIGENETICISTS AND NEUROSCIENTISTS. ACTIVATION OR INACTIVATION OF DIFFERENT EPIGENETIC PATHWAYS BECOMES MORE PRONOUNCED WHEN THE CELLS EXPERIENCE RAPID CHANGES IN THEIR ENVIRONMENT, AND SUCH CHANGES CAN BE EASILY CAUSED BY INJURY AND INFLAMMATION, RESULTING IN PAIN PERCEPTION OR DISTORTION OF PAIN PERCEPTION (EG, HYPERALGESIA). THEREFORE, IN THIS REGARD, THE FIELD OF PAIN IS AT AN ADVANTAGE TO STUDY THE EPIGENETIC PATHWAYS. MORE IMPORTANTLY, UNDERSTANDING PAIN FROM AN EPIGENETICS POINT OF VIEW WOULD PROVIDE A NEW PARADIGM FOR DEVELOPING DRUGS OR STRATEGIES FOR PAIN MANAGEMENT. IN THIS REVIEW, WE INTRODUCE BASIC CONCEPTS OF EPIGENETICS, INCLUDING CHROMATIN DYNAMICS, HISTONE MODIFICATIONS, DNA METHYLATION, AND RNA-INDUCED GENE SILENCING. IN ADDITION, WE PROVIDE EVIDENCE FROM PUBLISHED STUDIES SUGGESTING WIDE IMPLICATION OF DIFFERENT EPIGENETIC PATHWAYS WITHIN PAIN PATHWAYS. PERSPECTIVE: THIS ARTICLE PROVIDES A BRIEF OVERVIEW OF EPIGENETIC PATHWAYS FOR GENE REGULATION AND HIGHLIGHTS THEIR INVOLVEMENT IN PAIN. OUR GOAL IS TO EXPOSE THE READERS TO THESE CONCEPTS SO THAT PAIN-RELATED PHENOTYPES CAN BE INVESTIGATED FROM THE EPIGENETIC POINT OF VIEW. 2013 8 5927 30 TARGETING EPIGENETIC MECHANISMS FOR CHRONIC VISCERAL PAIN: A VALID APPROACH FOR THE DEVELOPMENT OF NOVEL THERAPEUTICS. BACKGROUND: CHRONIC VISCERAL PAIN IS PERSISTENT PAIN EMANATING FROM THORACIC, PELVIC, OR ABDOMINAL ORIGIN THAT IS POORLY LOCALIZED WITH REGARD TO THE SPECIFIC ORGAN AFFECTED. THE PREVALENCE CAN RANGE UP TO 25% IN THE ADULT POPULATION AS CHRONIC VISCERAL PAIN IS A COMMON FEATURE OF MANY VISCERAL DISORDERS, WHICH MAY OR MAY NOT BE ACCOMPANIED BY DISTINCT STRUCTURAL OR HISTOLOGICAL ABNORMALITIES WITHIN THE VISCERAL ORGANS. MOUNTING EVIDENCE SUGGESTS THAT CHANGES IN EPIGENETIC MECHANISMS ARE INVOLVED IN THE TOP-DOWN OR BOTTOM-UP SENSITIZATION OF PAIN PATHWAYS AND THE DEVELOPMENT OF CHRONIC PAIN. EPIGENETIC CHANGES CAN LEAD TO LONG-TERM ALTERATIONS IN GENE EXPRESSION PROFILES OF NEURONS AND CONSEQUENTLY ALTER FUNCTIONALITY OF PERIPHERAL NEURONS, DORSAL ROOT GANGLIA, SPINAL CORD, AND BRAIN NEURONS. HOWEVER, EPIGENETIC MODIFICATIONS ARE DYNAMIC, AND THUS, DETRIMENTAL CHANGES MAY BE REVERSIBLE. HENCE, EXTERNAL FACTORS/THERAPEUTIC INTERVENTIONS MAY BE CAPABLE OF MODULATING THE EPIGENOME AND RESTORE NORMAL GENE EXPRESSION FOR EXTENDED PERIODS OF TIME. PURPOSE: THE GOAL OF THIS REVIEW IS TO HIGHLIGHT THE LATEST DISCOVERIES MADE TOWARD UNDERSTANDING THE EPIGENETIC MECHANISMS THAT ARE INVOLVED IN THE DEVELOPMENT OR MAINTENANCE OF CHRONIC VISCERAL PAIN. FURTHERMORE, THIS REVIEW WILL PROVIDE EVIDENCE SUPPORTING THAT TARGETING THESE EPIGENETIC MECHANISMS MAY REPRESENT A NOVEL APPROACH TO TREAT CHRONIC VISCERAL PAIN. 2019 9 1686 28 DRUGGING THE PAIN EPIGENOME. MORE THAN 20% OF ADULTS WORLDWIDE EXPERIENCE DIFFERENT TYPES OF CHRONIC PAIN, WHICH ARE FREQUENTLY ASSOCIATED WITH SEVERAL COMORBIDITIES AND A DECREASE IN QUALITY OF LIFE. SEVERAL APPROVED PAINKILLERS ARE AVAILABLE, BUT CURRENT ANALGESICS ARE OFTEN HAMPERED BY INSUFFICIENT EFFICACY AND/OR SEVERE ADVERSE EFFECTS. CONSEQUENTLY, NOVEL STRATEGIES FOR SAFE, HIGHLY EFFICACIOUS TREATMENTS ARE HIGHLY DESIRABLE, PARTICULARLY FOR CHRONIC PAIN. EPIGENETIC MECHANISMS SUCH AS DNA METHYLATION, HISTONE MODIFICATIONS AND MICRORNAS (MIRNAS) STRONGLY AFFECT THE REGULATION OF GENE EXPRESSION, POTENTIALLY FOR LONG PERIODS OVER YEARS OR EVEN GENERATIONS, AND HAVE BEEN ASSOCIATED WITH PATHOPHYSIOLOGICAL PAIN. SEVERAL STUDIES, MOSTLY IN ANIMALS, REVEALED THAT INHIBITORS OF DNA METHYLATION, ACTIVATORS AND INHIBITORS OF HISTONE MODIFICATION AND MODULATORS OF MIRNAS REVERSE A NUMBER OF PATHOLOGICAL CHANGES IN THE PAIN EPIGENOME, WHICH ARE ASSOCIATED WITH ALTERED EXPRESSION OF PAIN-RELEVANT GENES. THIS EPIGENETIC MODULATION MIGHT THEN REDUCE THE NOCICEPTIVE RESPONSE AND PROVIDE NOVEL THERAPEUTIC OPTIONS FOR ANALGESIC THERAPY OF CHRONIC PAIN STATES. HOWEVER, A NUMBER OF CHALLENGES, SUCH AS NONSPECIFIC EFFECTS AND POOR DELIVERY TO TARGET CELLS AND TISSUES, HINDER THE RAPID DEVELOPMENT OF SUCH ANALGESICS. IN THIS REVIEW, WE CRITICALLY SUMMARIZE DATA ON EPIGENETICS AND PAIN, FOCUSING ON CHALLENGES IN CLINICAL DEVELOPMENT AS WELL AS POSSIBLE NEW APPROACHES TO THE DRUG MODULATION OF THE PAIN EPIGENOME. 2017 10 1204 31 COULD TARGETING EPIGENETIC PROCESSES RELIEVE CHRONIC PAIN STATES? PURPOSE OF REVIEW: ABERRATIONS IN THE EPIGENETIC LANDSCAPE HAVE PREVIOUSLY BEEN ASSOCIATED WITH HUMAN DISEASES SUCH AS CANCER AND SCHIZOPHRENIA, AND DRUGS THAT TARGET EPIGENETIC PROCESSES ARE CURRENTLY USED AS THERAPEUTIC AGENTS. THIS ARTICLE WILL REVIEW THE EVIDENCE OBTAINED FROM ANIMAL STUDIES INDICATING THAT EPIGENETIC PROCESSES MIGHT REGULATE LONG-TERM PAIN STATES AND THEN DISCUSS THE POSSIBILITY THAT TARGETING EPIGENETIC MECHANISMS MIGHT BE USEFUL FOR THE MANAGEMENT OF CHRONIC PAIN. RECENT FINDINGS: RECENT ANIMAL STUDIES HAVE REPORTED INJURY-INDUCED CHANGES IN EPIGENETIC PROCESSES IN THE CENTRAL NERVOUS SYSTEM. THE PICTURE THAT HAS EMERGED IS THAT OF VERY COMPLEX EPIGENETIC PROGRAMS THAT DEPEND ON THE INJURY. HOWEVER, SOME STUDIES HAVE REPORTED THE SUCCESSFUL USE OF NONSPECIFIC EPIGENETIC TOOLS TO IMPROVE THE HYPERSENSITIVITY THAT DEVELOPS IN ANIMAL MODELS OF LONG-TERM PAIN STATES. SUMMARY: THE FIELD OF EPIGENETICS AND PAIN IS RAPIDLY EMERGING BUT FURTHER INVESTIGATION IS NEEDED TO FULLY COMPREHEND THE CONTRIBUTION OF EPIGENETIC PROCESSES TO CHRONIC PAIN STATES. ALTHOUGH THERAPEUTIC APPROACHES TARGETING THESE MECHANISMS MIGHT SEEM WORTHWHILE, WE CANNOT ASSERT THAT CURRENTLY AVAILABLE GLOBAL TOOLS SUCH AS HISTONE DEACETYLASE INHIBITORS CAN BE USED SUCCESSFULLY FOR THE LONG-TERM TREATMENT OF CHRONIC PAIN STATES. 2015 11 47 31 A CONCEPTUAL MODEL OF BIOPSYCHOSOCIAL MECHANISMS OF TRANSITION FROM ACUTE TO CHRONIC POSTSURGICAL PAIN IN CHILDREN AND ADOLESCENTS. ACUTE AND CHRONIC PAIN ARE HIGHLY PREVALENT AND IMPACTFUL CONSEQUENCES OF SURGERY ACROSS THE LIFESPAN, YET A COMPREHENSIVE CONCEPTUAL MODEL ENCOMPASSING BIOPSYCHOSOCIAL FACTORS UNDERLYING ACUTE TO CHRONIC PAIN TRANSITION IS LACKING, PARTICULARLY IN YOUTH. BUILDING ON PRIOR CHRONIC POSTSURGICAL PAIN MODELS, WE PROPOSE A NEW CONCEPTUAL MODEL OF BIOPSYCHOSOCIAL MECHANISMS OF TRANSITION FROM ACUTE TO CHRONIC POSTSURGICAL PAIN. THIS REVIEW AIMS TO SUMMARIZE EXISTING RESEARCH EXAMINING KEY FACTORS UNDERLYING ACUTE TO CHRONIC POSTSURGICAL PAIN TRANSITION IN ORDER TO GUIDE PREVENTION AND INTERVENTION EFFORTS AIMED AT ADDRESSING THIS HEALTH ISSUE IN CHILDREN. AS PAIN TRANSITIONS FROM ACUTE NOCICEPTIVE PAIN TO CHRONIC PAIN, CHANGES IN THE PERIPHERAL AND CENTRAL NERVOUS SYSTEM CONTRIBUTE TO THE CHRONIFICATION OF PAIN AFTER SURGERY. THESE CHANGES INCLUDE ALTERATIONS IN SENSORY PAIN PROCESSING AND PSYCHOSOCIAL PROCESSES (PSYCHOLOGICAL, BEHAVIORAL, AND SOCIAL COMPONENTS), WHICH PROMOTE THE DEVELOPMENT OF CHRONIC PAIN. PATIENT-RELATED PREMORBID FACTORS (EG, DEMOGRAPHIC FACTORS, GENETIC PROFILE, AND MEDICAL FACTORS SUCH AS PREMORBID PAIN) MAY FURTHER MODULATE THESE CHANGES. FACTORS RELATED TO ACUTE INJURY AND RECOVERY (EG, SURGICAL AND TREATMENT FACTORS), AS WELL AS BIOLOGICAL RESPONSE TO SURGERY (EG, EPIGENETIC, INFLAMMATORY, AND ENDOCRINE FACTORS), MAY ALSO INFLUENCE THIS PROCESS. OVERALL, LONGITUDINAL STUDIES EXAMINING TEMPORAL PATHWAYS OF BIOPSYCHOSOCIAL PROCESSES INCLUDING BOTH RISK AND RESILIENCY FACTORS WILL BE ESSENTIAL TO IDENTIFY THE MECHANISMS INVOLVED IN THE TRANSITION FROM ACUTE TO CHRONIC PAIN. RESEARCH IS ALSO NEEDED TO UNRAVEL CONNECTIONS BETWEEN THE ACUTE PAIN EXPERIENCE, OPIOID EXPOSURE, AND SENSORY PAIN PROCESSING DURING ACUTE TO CHRONIC PAIN TRANSITION. FURTHERMORE, FUTURE STUDIES SHOULD INCLUDE LARGER AND MORE DIVERSE SAMPLES TO MORE FULLY EXPLORE RISK FACTORS IN A BROADER RANGE OF PEDIATRIC SURGERIES. THE USE OF CONCEPTUAL MODELS TO GUIDE INTERVENTION APPROACHES TARGETING MECHANISMS OF TRANSITION FROM ACUTE TO CHRONIC PAIN WILL SIGNIFICANTLY ADVANCE THIS FIELD AND IMPROVE OUTCOMES FOR CHILDREN AND ADOLESCENTS UNDERGOING SURGERY. 2020 12 3010 35 GENETICS AND EPIGENETICS IN PERIOPERATIVE MEDICINE. PURPOSE OF REVIEW: TO SUMMARIZE IS TO REVIEW RECENT PROGRESS IN 'GENOMIC' SCIENCE AND HOW THIS MAY BE APPLIED TO THE PERIOPERATIVE ENVIRONMENT. ALTHOUGH INVESTIGATIONS THAT RELATE GENETIC VARIATION TO PERIOPERATIVE OUTCOMES CONTINUE, IT IS INCREASINGLY APPARENT THAT EPIGENETIC MECHANISMS MAY CONTRIBUTE TO MUCH OF THE OBSERVED VARIATION IN COMPLEX OUTCOMES NOT OTHERWISE EXPLAINED BY DIFFERENCES IN GENETIC SEQUENCE. RECENT FINDINGS: EXAMPLES OF RECENT FINDINGS RELATING TO THE ROLE OF EPIGENETIC MODIFICATIONS IN COMPLEX DISEASE AND OUTCOMES ARE DERIVED FROM RESEARCH INTO TYPE 1 DIABETES, PAIN, AND THE HYPOXIC RESPONSE. THESE STUDIES PROVIDE MODELS FOR FUTURE COHORT STUDY DESIGN, POTENTIAL PERIOPERATIVE DRUG TARGETS, AND HYPOTHESIS DEVELOPMENT. GENETIC AND EPIGENETIC FACTORS COMBINE TO ALTER BOTH GENE EXPRESSION AND DRUG RESPONSES AT BOTH PHARMACOKINETIC AND PHARMACODYNAMIC LEVELS. THESE FACTORS IMPACT ON THE EFFICACY AND SAFETY OF MULTIPLE DRUG CLASSES USED IN PERIOPERATIVE MEDICINE. SUMMARY: ENHANCING OUR UNDERSTANDING OF THE WAY IN WHICH PATIENTS AS GENOMIC ORGANISMS INTERACT WITH THE PERIOPERATIVE ENVIRONMENT REQUIRES A MORE SOPHISTICATED APPRECIATION OF THE FACTORS GOVERNING GENE EXPRESSION THAN HAS BEEN THE CASE TO DATE. EPIGENETIC MECHANISMS ARE SURE TO PLAY A PIVOTAL ROLE IN WHAT IS ESSENTIALLY AN ACQUIRED PHENOTYPE. 2012 13 5038 17 PHARMACOGENETICS OF CHRONIC PAIN AND ITS TREATMENT. THIS PAPER REVIEWS THE IMPACT OF GENETIC VARIABILITY OF DRUG METABOLIZING ENZYMES, TRANSPORTERS, RECEPTORS, AND PATHWAYS INVOLVED IN CHRONIC PAIN PERCEPTION ON THE EFFICACY AND SAFETY OF ANALGESICS AND OTHER DRUGS USED FOR CHRONIC PAIN TREATMENT. SEVERAL CANDIDATE GENES HAVE BEEN IDENTIFIED IN THE LITERATURE, WHILE THERE IS USUALLY ONLY LIMITED CLINICAL EVIDENCE SUBSTANTIATING FOR THE PENETRATION OF THE TESTING FOR THESE CANDIDATE BIOMARKERS INTO THE CLINICAL PRACTICE. FURTHER, THE PAIN-PERCEPTION REGULATION AND MODULATION ARE STILL NOT FULLY UNDERSTOOD, AND THUS MORE COMPLEX KNOWLEDGE OF GENETIC AND EPIGENETIC BACKGROUND FOR ANALGESIA WILL BE NEEDED PRIOR TO THE CLINICAL USE OF THE CANDIDATE GENETIC BIOMARKERS. 2013 14 6828 22 [GLOBAL UNDERSTANDING OF PAIN]. CLINICALLY, IT IS WELL-KNOWN THAT CHRONIC PAIN INDUCES DEPRESSION, ANXIETY, AND REDUCED QUALITY OF LIFE. NEUROPATHIC PAIN, WHICH IS CHARACTERIZED BY SPONTANEOUS BURNING PAIN, HYPERALGESIA AND ALLODYNIA, IS THE MOST DIFFICULT PAIN TO MANAGE IN THE PAIN CLINIC. HOWEVER, THE COMPLICATED PATHOPHYSIOLOGY OF NEUROPATHIC PAIN IS NOT YET UNDERSTOOD. A BETTER UNDERSTANDING OF ITS PATHOPHYSIOLOGY HAS GIVEN US MORE INSIGHT INTO ITS VARIOUS MECHANISMS AND POSSIBLE TREATMENT OPTIONS. THIS REVIEW WILL EXPLORE THE MOST CURRENT ISSUES IN THE FIELD OF PAIN, WITH A FOCUS ON TRANSCRIPTIONAL RESEARCH, EPIGENETIC RESEARCH AND POST-TRANSCRIPTIONAL RESEARCH. FOR A GLOBAL UNDERSTANDING OF THE PAIN, IT IS NECESSARY TO ANALYZE THE CORRELATION BETWEEN THESE TEMPORAL PARAMETERS AND PHENOMICS. 2012 15 2194 29 EPIGENETIC MODIFICATION IN NEUROPATHIC PAIN. NEUROPATHIC PAIN IS CHARACTERIZED BY COMPLICATED COMBINATION OF POSITIVE (E.G., HYPERALGESIA AND ALLODYNIA) AND NEGATIVE (E.G., HYPOESTHESIA AND HYPOALGESIA) SYMPTOMS, AND IS OFTEN REFRACTORY TO CONVENTIONAL PHARMACOLOGICAL AGENTS, INCLUDING MORPHINE. ALTHOUGH THE MOLECULAR MECHANISMS FOR POSITIVE SYMPTOMS ARE EXTENSIVELY STUDIED, THOSE FOR NEGATIVE SYMPTOMS ARE POORLY UNDERSTOOD. THERE IS CONVINCING EVIDENCE THAT ALTERED GENE EXPRESSION WITHIN PERIPHERAL AND CENTRAL NERVOUS SYSTEMS IS A KEY MECHANISM FOR NEUROPATHIC PAIN; HOWEVER, ITS TRANSCRIPTIONAL MECHANISMS ARE POORLY UNDERSTOOD. EPIGENETIC MODIFICATIONS, SUCH AS DNA METHYLATION AND HISTONE MODIFICATIONS (E.G., ACETYLATION, METHYLATION, AND PHOSPHORYLATION), ARE KNOWN TO CAUSE STABLE GENE EXPRESSION VIA CHROMATIN REMODELING. THESE MECHANISMS HAVE A ROLE NOT ONLY IN THE DETERMINATION OF DEVELOPMENTAL CELL FATES, BUT ALSO IN THE PHYSIOLOGICAL AND PATHOLOGICAL PROCESSES IN NERVOUS SYSTEM. MOREOVER, EPIGENETIC THERAPIES USING EPIGENETIC MODIFYING COMPOUNDS ARE PROGRESSIVELY ADVANCED IN THE TREATMENTS OF DIVERSE DISEASES, INCLUDING CANCER AND NEUROLOGICAL DISEASES. IMPORTANTLY, THERE IS EMERGING EVIDENCE THAT A VARIETY OF GENES UNDERGO EPIGENETIC REGULATION VIA DNA METHYLATION AND HISTONE MODIFICATIONS WITHIN PERIPHERAL AND CENTRAL NERVOUS SYSTEMS, THEREBY CONTRIBUTING TO THE ALTERATIONS IN BOTH PAIN SENSITIVITY AND PHARMACOLOGICAL EFFICACY IN NEUROPATHIC PAIN. IN THIS REVIEW, WE WILL HIGHLIGHT THE EPIGENETIC GENE REGULATION UNDERLYING NEUROPATHIC PAIN, ESPECIALLY FOCUSING ON THE NEGATIVE SYMPTOMS. MOREOVER, WE WILL DISCUSS WHETHER EPIGENETIC MECHANISMS CAN SERVE AS A POTENTIAL TARGET TO TREAT NEUROPATHIC PAIN. 2015 16 6458 35 TIME COURSE OF DNA METHYLATION IN PAIN CONDITIONS: FROM EXPERIMENTAL MODELS TO HUMANS. BACKGROUND AND OBJECTIVE: THROUGHOUT THE LAST DECADE, RESEARCH HAS UNCOVERED ASSOCIATIONS BETWEEN PAIN AND EPIGENETIC ALTERATIONS CAUSED BY ENVIRONMENTAL FACTORS. SPECIFICALLY, STUDIES HAVE DEMONSTRATED CORRELATIONS BETWEEN PAIN CONDITIONS AND ALTERED DNA METHYLATION PATTERNS. THUS, DNA METHYLATION HAS BEEN REVEALED AS A POSSIBLE MODULATOR OR CONTRIBUTOR TO PAIN CONDITIONS, PROVIDING A POTENTIAL THERAPEUTIC TARGET FOR TREATMENT BY DNA METHYLATION MODIFICATION. TO DEVELOP SUCH TREATMENTS, IT IS NECESSARY TO CLARIFY A WIDE NUMBER OF ASPECTS ON HOW DNA METHYLATION AFFECTS PAIN PERCEPTION; FIRST AND FOREMOST, THE TEMPORAL DYNAMICS. THE OBJECTIVE OF THE PRESENT REVIEW IS TO PROVIDE AN OVERVIEW OF CURRENT KNOWLEDGE ON TEMPORAL DYNAMICS OF DNA METHYLATION IN RESPONSE TO PAIN, AND TO INVESTIGATE IF A TIMEFRAME CAN BE ESTABLISHED BASED ON THE DATA OF CURRENTLY PUBLISHED STUDIES. DATABASES AND DATA TREATMENT: PUBMED, MEDLINE, GOOGLE SCHOLAR AND EMBASE WERE SEARCHED COMPREHENSIVELY FOR STUDIES OF DNA METHYLATION IN NEUROPATHIC, INFLAMMATORY AND ALTERNATIVE ANIMAL PAIN MODELS, AND IN CHRONIC PAIN PATIENTS INCLUDING COMPLEX REGIONAL PAIN SYNDROME, CHRONIC POSTSURGICAL PAIN, CHRONIC WIDESPREAD PAIN, FIBROMYALGIA AND CROHN'S DISEASE. RESULTS: WE IDENTIFIED 34 ARTICLES HIGHLIGHTING VARIATIONS IN TEMPORAL DYNAMICS OF DNA METHYLATION ACROSS SPECIES AND BETWEEN DIFFERENT TYPES OF PAIN. THESE STUDIES REPRESENT A STARTING POINT TO UNCOVER NEW INSIGHTS IN THE DNA METHYLATION TIME COURSE IN PAIN. CONCLUSIONS: NO TIMEFRAME CAN CURRENTLY BE MADE FOR THE DNA METHYLATION RESPONSE TO PAIN IN ANY OF THE REVIEWED CONDITIONS, HIGHLIGHTING AN IMPORTANT FOCUS AREA FOR FUTURE RESEARCH. 2021 17 2551 25 EPIGENETICS IN PAIN AND ANALGESIA: AN IMMINENT RESEARCH FIELD. HERITABLE PHENOTYPES RESULTING FROM ENVIRONMENT-CAUSED CHANGES IN A CHROMOSOME WITHOUT ALTERATIONS IN THE DNA SEQUENCE ARE INCREASINGLY RECOGNIZED AS A BASIS OF PERSONALIZED THERAPY. EPIGENETIC MECHANISMS INCLUDE COVALENT MODIFICATIONS OF THE DNA (METHYLATION) OR OF THE DNA-PACKAGING HISTONES (E.G., DEACETYLATION OR PHOSPHORYLATION). IN ADDITION, REGULATORY NON-CODING RNA MOLECULES (MICRO-RNAS) EXERT EPIGENETIC ACTIONS. THIS LEADS TO DISRUPTION OR OTHERWISE MODIFIED EXPRESSION OF GENES. ENVIRONMENTAL INFLUENCES SUCH AS NUTRITIONAL FACTORS, EXPOSURE TO CHEMICALS OR DRUGS, BUT ALSO SOCIAL FACTORS APPEAR TO EXERT EPIGENETIC ACTIONS. HISTONE MODIFICATIONS AND DNA METHYLATION ARE ASSOCIATED WITH THE SUBJECT'S AGE. EPIGENETIC MECHANISMS CAN SILENCE THE EXPRESSION OF PRO- OR ANTINOCICEPTIVE GENES. TO THE EPIGENETIC CONTROL OF NOCICEPTION ADDS ITS CONTROL OF THE PHARMACODYNAMICS OR PHARMACOKINETICS OF ANALGESICS BY EPIGENETIC CONTROL OF DRUG TARGETS AND ANALGESICS METABOLIZING ENZYMES. ALTHOUGH EPIGENETICS-BASED STRATEGIES FOR PAIN THERAPY ARE NOT YET AVAILABLE, EXPERIMENTS IN RODENTS SUGGEST THAT RNA INTERFERENCE MAY BECOME A NEW THERAPY APPROACH FOR NEUROPATHIC AND OTHER PAIN. ANOTHER EPIGENETIC APPROACH TO ANALGESIC TREATMENT EMPLOYS INHIBITORS OF HISTONE DEACETYLASE THAT ACT ON THE EPIGENOME BY INDIRECTLY REMODELING THE SPATIAL CONFORMATION OF THE CHROMATIN. FINALLY, EPIGENETIC TECHNIQUES SUCH AS RNA INTERFERENCE HAVE BEEN EMPLOYED IN PAIN RESEARCH TO PROOF THE CONTRIBUTION OF CERTAIN PROTEINS TO NOCICEPTION. THUS, THE NEW FIELD OF EPIGENETICS BECOMES INCREASINGLY USED IN RESEARCH AND MANAGEMENT OF PAIN AND WILL COMPLEMENT GENETICS. THIS ARTICLE INTRODUCES EPIGENETICS TO PAIN AND SUMMARIZES THE CURRENT AND FUTURE UTILITY. 2011 18 3108 24 GENOMICS OF PAIN IN OSTEOARTHRITIS. OSTEOARTHRITIS (OA) ACCOUNTS FOR THE MAJORITY OF THE DISEASE BURDEN FOR MUSCULOSKELETAL DISORDERS AND IS ONE OF THE LEADING CAUSES OF DISABILITY WORLDWIDE. THIS DISABILITY IS THE RESULT NOT OF THE CARTILAGE LOSS THAT DEFINES OA RADIOGRAPHICALLY, BUT OF THE CHRONIC PAIN WHOSE PRESENCE DEFINES SYMPTOMATIC OA. IT IS BECOMING CLEAR THAT MANY GENES, EACH WITH A SMALL EFFECT SIZE, CONTRIBUTE TO THE RISK OF DEVELOPING OA. HOWEVER, THE GENETICS OF OA PAIN ARE ONLY JUST STARTING TO BE EXPLORED. THIS REVIEW WILL DESCRIBE THE FIRST GENES TO HAVE BEEN IDENTIFIED IN GENOMIC STUDIES OF OA PAIN, AS WELL AS THE POSSIBLE DUAL ROLES OF GENES PREVIOUSLY IDENTIFIED IN GENOMIC STUDIES OF OA IN THE CONTEXT OF PAIN. DIFFICULTIES ASSOCIATED WITH ATTEMPTING TO CHARACTERISE THE GENETICS OF OA PAIN WILL BE DISCUSSED AND PROMISING FUTURE AVENUES OF RESEARCH INTO GENETIC AND EPIGENETIC FACTORS AFFECTING OA PAIN DESCRIBED. 2013 19 6866 26 [PAIN AND EMOTIONAL DYSREGULATION: CELLULAR MEMORY DUE TO PAIN]. GENETIC FACTORS ARE INVOLVED IN DETERMINANTS FOR THE RISK OF PSYCHIATRIC DISORDERS, AND NEUROLOGICAL AND NEURODEGENERATIVE DISEASES. CHRONIC PAIN STIMULI AND INTENSE PAIN HAVE EFFECTS AT A CELLULAR AND/OR GENE EXPRESSION LEVEL, AND WILL EVENTUALLY INDUCE "CELLULAR MEMORY DUE TO PAIN", WHICH MEANS THAT TISSUE DAMAGE, EVEN IF ONLY TRANSIENT, CAN ELICIT EPIGENETICALLY ABNORMAL TRANSCRIPTION/TRANSLATION AND POST-TRANSLATIONAL MODIFICATION IN RELATED CELLS DEPENDING ON THE DEGREE OR KIND OF INJURY OR ASSOCIATED CONDITIONS. SUCH CELL MEMORY/TRANSFORMATION DUE TO PAIN CAN CAUSE AN ABNORMALITY IN A FUNDAMENTAL INTRACELLULAR RESPONSE, SUCH AS A CHANGE IN THE THREE-DIMENSIONAL STRUCTURE OF DNA, TRANSCRIPTION, OR TRANSLATION. ON THE OTHER HAND, PAIN IS A MULTIDIMENSIONAL EXPERIENCE WITH SENSORY-DISCRIMINATIVE AND MOTIVATIONAL-AFFECTIVE COMPONENTS. RECENT HUMAN BRAIN IMAGING STUDIES HAVE EXAMINED DIFFERENCES IN ACTIVITY IN THE NUCLEUS ACCUMBENS BETWEEN CONTROLS AND PATIENTS WITH CHRONIC PAIN, AND HAVE REVEALED THAT THE NUCLEUS ACCUMBENS PLAYS A ROLE IN PREDICTING THE VALUE OF A NOXIOUS STIMULUS AND ITS OFFSET, AND IN THE CONSEQUENT CHANGES IN THE MOTIVATIONAL STATE. IN THIS REVIEW, WE PROVIDE A VERY BRIEF OVERVIEW OF A COMPREHENSIVE UNDERSTANDING OF CHRONIC PAIN ASSOCIATED WITH EMOTIONAL DYSREGULATION DUE TO TRANSCRIPTIONAL REGULATION, EPIGENETIC MODIFICATION AND MIRNA REGULATION. 2015 20 5369 28 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