1 4139 95 MECHANISMS OF MIGRAINE AS A CHRONIC EVOLUTIVE CONDITION. UNDERSTANDING THE MECHANISMS OF MIGRAINE REMAINS CHALLENGING AS MIGRAINE IS NOT A STATIC DISORDER, AND EVEN IN ITS EPISODIC FORM MIGRAINE REMAINS AN "EVOLUTIVE" CHRONIC CONDITION. CONSIDERABLE PROGRESS HAS BEEN MADE IN ELUCIDATING THE PATHOPHYSIOLOGICAL MECHANISMS OF MIGRAINE, ASSOCIATED GENETIC FACTORS THAT MAY INFLUENCE SUSCEPTIBILITY TO THE DISEASE, AND FUNCTIONAL AND ANATOMICAL CHANGES DURING THE PROGRESSION OF A MIGRAINE ATTACK OR THE TRANSFORMATION OF EPISODIC TO CHRONIC MIGRAINE. MIGRAINE IS A LIFE SPAN NEUROLOGICAL DISORDER THAT FOLLOWS AN EVOLUTIVE AGE-DEPENDENT CHANGE IN ITS PREVALENCE AND EVEN CLINICAL PRESENTATIONS. AS A DISORDER, MIGRAINE INVOLVES RECURRENT INTENSE HEAD PAIN AND ASSOCIATED UNPLEASANT SYMPTOMS. MIGRAINE ATTACKS EVOLVE OVER DIFFERENT PHASES WITH SPECIFIC NEURAL MECHANISMS AND SYMPTOMS BEING INVOLVED DURING EACH PHASE. IN SOME PATIENTS, MIGRAINE CAN BE TRANSFORMED INTO A CHRONIC FORM WITH DAILY OR ALMOST DAILY HEADACHES. THE MECHANISMS BEHIND THIS EVOLUTIVE PROCESS REMAIN UNKNOWN, BUT GENETIC AND EPIGENETIC FACTORS, INFLAMMATORY PROCESSES AND CENTRAL SENSITIZATION MAY PLAY AN IMPORTANT ROLE. 2019 2 5387 38 REDOX MECHANISMS IN MIGRAINE: NOVEL THERAPEUTICS AND DIETARY INTERVENTIONS. SIGNIFICANCE: MIGRAINE REPRESENTS THE THIRD MOST PREVALENT AND THE SEVENTH MOST DISABLING HUMAN DISORDER. APPROXIMATELY 30% OF MIGRAINE PATIENTS EXPERIENCE TRANSIENT, FULLY REVERSIBLE, FOCAL NEUROLOGICAL SYMPTOMS (AURA) PRECEDING THE ATTACK. RECENT ADVANCES: AWARENESS OF THE HYPOTHESIS THAT MIGRAINE ACTUALLY EMBODIES A SPECTRUM OF ILLNESSES-RANGING FROM EPISODIC TO CHRONIC FORMS-IS PROGRESSIVELY INCREASING AND POSES NOVEL CHALLENGES FOR CLARIFYING THE UNDERLYING PATHOPHYSIOLOGICAL MECHANISMS OF MIGRAINE AS WELL AS FOR THE DEVELOPMENT OF NOVEL THERAPEUTIC INTERVENTIONS. SEVERAL THEORIES HAVE EVOLVED TO THE CURRENT CONCEPT THAT A COMBINATION OF GENETIC, EPIGENETIC, AND ENVIRONMENTAL FACTORS MAY PLAY A ROLE IN MIGRAINE PATHOGENESIS, ALTHOUGH THEIR RELATIVE IMPORTANCE IS STILL BEING DEBATED. CRITICAL ISSUES: ONE CRITICAL ISSUE THAT DESERVES A PARTICULAR ATTENTION IS THE ROLE OF OXIDATIVE STRESS IN MIGRAINE. INDEED, POTENTIALLY HARMFUL OXIDATIVE EVENTS OCCUR DURING THE MIGRAINE ATTACK AND LONG-LASTING OR FREQUENT MIGRAINE EPISODES MAY INCREASE BRAIN EXPOSURE TO OXIDATIVE EVENTS THAT CAN LEAD TO CHRONIC TRANSFORMATION. MOREOVER, A WIDE VARIETY OF DIETARY, ENVIRONMENTAL, PHYSIOLOGICAL, BEHAVIORAL, AND PHARMACOLOGICAL MIGRAINE TRIGGERS MAY ACT THROUGH OXIDATIVE STRESS, WITH CLEAR IMPLICATIONS FOR MIGRAINE TREATMENT AND PROPHYLAXIS. INTERESTINGLY, ALMOST ALL CURRENT PROPHYLACTIC MIGRAINE AGENTS EXERT ANTIOXIDANT EFFECTS. FUTURE DIRECTIONS: INCREASING AWARENESS OF THE ROLE OF OXIDATIVE STRESS AND/OR DECREASED ANTIOXIDANT DEFENSES IN MIGRAINE PATHOGENESIS AND PROGRESSION TO A CHRONIC CONDITION LAYS THE FOUNDATIONS FOR THE DESIGN OF NOVEL PROPHYLACTIC APPROACHES, WHICH, BY REDUCING BRAIN OXIDATIVE PHENOMENA, COULD FAVORABLY MODIFY THE CLINICAL COURSE OF MIGRAINE. ANTIOXID. REDOX SIGNAL. 28, 1144-1183. 2018 3 638 39 BIOMARKERS ASSOCIATED WITH MIGRAINE AND THEIR POTENTIAL ROLE IN MIGRAINE MANAGEMENT. OBJECTIVE: THE FOCUS OF THIS REVIEW IS TO REVIEW POTENTIAL DIAGNOSTIC AND THERAPEUTIC BIOMARKERS ASSOCIATED WITH MIGRAINE. BACKGROUND: MIGRAINE HEADACHE IS A COMMON DISEASE THAT AFFECTS MILLIONS OF INDIVIDUALS WORLDWIDE. ALTHOUGH WELL-ACCEPTED DIAGNOSTIC CRITERIA EXIST FOR MIGRAINE, IT IS STILL A COMPLEX DISORDER THAT REMAINS BOTH UNDERDIAGNOSED AND MISDIAGNOSED. THE CAUSES OF MIGRAINE ARE LIKELY A MIX OF GENETIC, EPIGENETIC, AND ENVIRONMENTAL FACTORS THAT, TOGETHER WITH THE INDIVIDUAL'S LIFE HISTORY, TRANSLATE INTO THE OBSERVED CLINICAL HETEROGENEITY. INHERENT CLINICAL HETEROGENEITY IS AN OBSTACLE IN DEVELOPING MORE EFFECTIVE TREATMENTS. THE LACK OF APPROPRIATE BIOMARKERS IS ALSO AN IMPEDIMENT TO DEVELOPING MORE EFFECTIVE THERAPEUTIC/PREVENTIVE APPROACHES. ULTIMATELY, BIOMARKERS MAY FACILITATE THE GOAL OF INDIVIDUALIZED MEDICINE BY ENABLING CLINICIANS TO MORE ACCURATELY DIAGNOSE AND TREAT MIGRAINE AND OTHER TYPES OF HEADACHE. METHODS: A COMPREHENSIVE REVIEW WAS CONDUCTED OF PUBMED CITATIONS CONTAINING THE KEY WORD "MARKER" OR "BIOMARKER" COMBINED WITH "MIGRAINE" OR "HEADACHE." OTHER KEY WORDS INCLUDED "SERUM," "SALIVA," "CEREBROSPINAL FLUID," "GENES," "BLOOD," AND "INFLAMMATION." THE ONLY RESTRICTION WAS ENGLISH-LANGUAGE PUBLICATION. THE ABSTRACTS OF ALL ARTICLES MEETING THESE CRITERIA WERE REVIEWED, AND FULL TEXT WAS RETRIEVED AND EXAMINED FOR RELEVANT REFERENCES. RESULTS: DATA FROM HUMAN STUDIES HAVE BEGUN TO IDENTIFY GENETIC MUTATIONS/POLYMORPHISMS AND ALTERED LEVELS OF SPECIFIC PROINFLAMMATORY AND NEUROMODULATORY MOLECULES THAT STRONGLY CORRELATE WITH MIGRAINE AS WELL AS SYMPTOM SEVERITY. RESULTS FROM A SMALLER NUMBER OF STUDIES HAVE IDENTIFIED PARAMETERS, SUCH AS THE NEUROPEPTIDE CALCITONIN GENE-RELATED PEPTIDE (CGRP), WHICH ARE SIGNIFICANTLY ASSOCIATED WITH RESPONSE TO SPECIFIC TREATMENTS FOR ACUTE MIGRAINE ATTACKS AND PROPHYLAXIS. EPIGENETIC MECHANISMS MAY ALSO BE INVOLVED IN THE DEVELOPMENT OF MIGRAINE, AND UNDERSTANDING ENVIRONMENTALLY INDUCED GENETIC CHANGES ASSOCIATED WITH THIS DISEASE MAY EVENTUALLY GUIDE THE DEVELOPMENT OF THERAPIES CAPABLE OF REVERSING THESE PATHOPHYSIOLOGICAL CHANGES IN GENE FUNCTION. CONCLUSIONS: THE UNDERSTANDING OF THE ETIOLOGY OF MIGRAINE IS INCOMPLETE. ALTHOUGH THE IDENTIFICATION AND VALIDATION OF BIOMARKERS HAS GREATLY ADVANCED DIAGNOSTIC PRECISION AND MEASURES OF THERAPEUTIC EFFICACY IN OTHER DISEASES, THERE ARE NO CURRENTLY ACCEPTED BIOMARKERS FOR CHRONIC OR EPISODIC MIGRAINE. HOWEVER, THE CONTINUED INVESTIGATION AND IDENTIFICATION OF GENETIC, EPIGENETIC, AND MOLECULAR BIOMARKERS IS LIKELY TO FACILITATE THE GOAL OF INDIVIDUALIZING MEDICINE BY ENABLING CLINICIANS TO MORE ACCURATELY DIAGNOSE AND TREAT MIGRAINE AND OTHER HEADACHE DISORDERS. 2013 4 6846 33 [MIGRAINE: IGNITION OF THE BRAIN]. ALTHOUGH OUR KNOWLEDGE OF WHICH SYSTEMS ARE ACTIVATED DURING MIGRAINE IS REASONABLY COMPLETE, WHY THE SYSTEM IS ACTIVATED REMAINS UNKNOWN. INCORPORATING THE FINDINGS OBTAINED IN STUDIES ON PAIN IN GENERAL HAS ALLOWED A MORE INTEGRATED MODEL TO BE GENERATED. ACCORDING TO THIS NEW MODEL, THERE IS AN ANATOMICAL SUBSTRATE CONSISTING IN A COMPLEX FRAMEWORK OF PAIN THAT IS MADE UP NOT ONLY OF THE TRIGEMINOVASCULAR SYSTEM (END PATHWAY) BUT OF A NUMBER OF NETWORKS THAT ARE IN TURN CONNECTED TO ONE ANOTHER, LIKE THE NEUROLIMBIC, THE ASCENDING AND DESCENDING MODULATORY SYSTEM. THIS COMPLEX NETWORK IS RESPONSIBLE FOR MODULATING AND CONVEYING NOCICEPTIVE SIGNALS. IN PATIENTS WITH MIGRAINE, HYPEREXCITABILITY OF THIS FRAMEWORK IS CONDITIONED BY GENETIC AND EPIGENETIC ALTERATIONS. EPIGENETIC CHANGES ARE CHEMICAL MODIFICATIONS AFFECTING CHROMATIN, WHICH MODULATES THE ACTIVITY OF GENES WITHOUT MODIFYING THE DNA SEQUENCE, AND WHICH ARE CAPABLE OF MODULATING THE EXPRESSION OF GENES INVOLVED IN A NUMBER OF DIFFERENT ASPECTS, SUCH AS PLASTICITY, SYSTEM EXCITABILITY, MEMORY OF PAIN OR MOODS. IN TURN, THE PRESENCE OF EXTERNAL FACTORS (SUCH AS ENVIRONMENTAL CHANGES OR ALCOHOL) AND INTERNAL FACTORS (SUCH AS HORMONES OR SLEEP DISORDERS) CONTRIBUTE TO ACTIVATE THIS LOADED ANATOMICAL SUBSTRATE, RESULTING IN THE ATTACK OF MIGRAINE. 2013 5 2963 25 GENETIC AND EPIGENETIC MECHANISMS LINKING PAIN AND PSYCHIATRIC DISORDERS. THE NEUROPHYSIOLOGICAL LINK BETWEEN NEUROPATHIC PAIN AND DEPRESSION REMAINS UNKNOWN DESPITE EVIDENT HIGH COMORBIDITY OF THESE TWO DISORDERS. HOWEVER, THERE IS CONVINCING EVIDENCE THAT GENOTYPE PLAYS A ROLE IN BOTH PAIN AND DEPRESSION. USING VARIOUS TYPES OF GENETIC ANALYSIS - POPULATION GENETICS, CYTOGENETICS AND MOLECULAR TECHNOLOGIES - SPECIFIC GENES HAVE BEEN IMPLICATED IN MEDIATING ALMOST ALL ASPECTS OF NOCICEPTION AND MOOD DISORDERS. THE CURRENT REVIEW ATTEMPTS TO IDENTIFY SPECIFIC GENES AND EPIGENETIC MECHANISMS COMMON TO BOTH DISORDERS. IT IS CONCLUDED THAT EXTERNAL AND INTERNAL FACTORS (INFLAMMATION, STRESS, GENDER, ETC.) THAT CONTRIBUTE TO THE PATHOLOGIES MAY DO SO THROUGH EPIGENETIC MECHANISMS THAT MAY AFFECT EXPRESSION OF THESE PARTICULAR GENES. THE POSSIBLE INVOLVEMENT OF EPIGENETIC REGULATION IN PAIN AND PSYCHIATRIC DISORDERS SUGGESTS THAT TREATMENTS TARGETING EPIGENETIC MECHANISMS THAT MEDIATE ADVERSE LIFE EVENTS SHOULD BE CONSIDERED. 2015 6 3108 25 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 7 2611 22 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 6807 20 [EPIGENETICS AND PAIN]. CHRONIC PAIN AFFECTS APPROXIMATELY 20 % OF ADULTS WORLDWIDE AND IS OFTEN ASSOCIATED WITH A DECREASE IN THE QUALITY OF LIFE AND VARIOUS COMORBIDITIES. CONVENTIONAL ANALGESIC THERAPIES ARE FREQUENTLY INSUFFICIENT AND SOMETIMES LEAD TO SEVERE SIDE EFFECTS. THEREFORE, GREAT EFFORTS ARE STILL BEING MADE TO ELUCIDATE THE SIGNALLING PATHWAYS IN PAIN AND TO DEVELOP NEW, SAFE AND EFFECTIVE THERAPIES. EPIGENETIC MECHANISMS WHICH INTERFERE WITH THE REGULATION OF GENE EXPRESSION ARE INVOLVED IN THE PATHOGENESIS OF SEVERAL DISEASES AND ARE GAINING INCREASING IMPETUS IN MEDICAL RESEARCH. AS THEY ARE ALSO INVOLVED IN PAIN PROCESSING, A MODULATION OF THESE MECHANISMS MIGHT REPRESENT A NOVEL OPTION FOR THE THERAPY OF PAIN PATIENTS. 2014 9 3404 30 HOW EPIGENETICS IMPACTS ON HUMAN DISEASES. EPIGENETICS IS A RAPIDLY GROWING FIELD OF BIOLOGY THAT STUDIES THE CHANGES IN GENE EXPRESSION THAT ARE NOT DUE TO ALTERATIONS IN THE DNA SEQUENCE BUT RATHER THE CHEMICAL MODIFICATIONS OF DNA AND ITS ASSOCIATED PROTEINS. EPIGENETIC MECHANISMS CAN PROFOUNDLY INFLUENCE GENE EXPRESSION, CELL DIFFERENTIATION, TISSUE DEVELOPMENT, AND DISEASE SUSCEPTIBILITY. UNDERSTANDING EPIGENETIC CHANGES IS ESSENTIAL TO ELUCIDATE THE MECHANISMS UNDERLYING THE INCREASINGLY RECOGNIZED ROLE OF ENVIRONMENTAL AND LIFESTYLE FACTORS IN HEALTH AND DISEASE AND THE INTERGENERATIONAL TRANSMISSION OF PHENOTYPES. RECENT STUDIES SUGGEST EPIGENETICS MAY BE CRITICAL IN VARIOUS DISEASES, FROM CARDIOVASCULAR DISEASE AND CANCER TO NEURODEVELOPMENTAL AND NEURODEGENERATIVE DISORDERS. EPIGENETIC MODIFICATIONS ARE POTENTIALLY REVERSIBLE AND COULD PROVIDE NEW THERAPEUTIC AVENUES FOR TREATING THESE DISEASES USING EPIGENETIC MODULATORS. MOREOVER, EPIGENETICS PROVIDE INSIGHT INTO DISEASE PATHOGENESIS AND BIOMARKERS FOR DISEASE DIAGNOSIS AND RISK STRATIFICATION. NEVERTHELESS, EPIGENETIC INTERVENTIONS HAVE THE POTENTIAL FOR UNINTENDED CONSEQUENCES AND MAY POTENTIALLY LEAD TO INCREASED RISKS OF UNEXPECTED OUTCOMES, SUCH AS ADVERSE DRUG REACTIONS, DEVELOPMENTAL ABNORMALITIES, AND CANCER. THEREFORE, RIGOROUS STUDIES ARE ESSENTIAL TO MINIMIZE THE RISKS ASSOCIATED WITH EPIGENETIC THERAPIES AND TO DEVELOP SAFE AND EFFECTIVE INTERVENTIONS FOR IMPROVING HUMAN HEALTH. THIS ARTICLE PROVIDES A SYNTHETIC AND HISTORICAL VIEW OF THE ORIGIN OF EPIGENETICS AND SOME OF THE MOST RELEVANT ACHIEVEMENTS. 2023 10 6916 27 [WHAT IS MIGRAINE?]. MIGRAINE IS A MULTIFACTORIAL AND HETEROGENEOUS DISORDER. DIAGNOSTIC CRITERIA HAVE BEEN ESTABLISHED BY THE INTERNATIONAL HEADACHE SOCIETY, HOWEVER THESE ARE ONLY SUPPORTIVE IN TERMS OF DEFINITION. THE PATHOPHYSIOLOGY INVOLVES NEURONAL AND VASCULAR PHENOMENA. THE FORMER IS SUPPORTED BY THE CORTICAL SPREADING DEPRESSION BEING THE AURA CORRELATE AND BY BRAINSTEM AND HYPOTHALAMIC ACTIVATION DURING THE PAIN PHASE; THE LATTER IS SUGGESTED BY THE ASSOCIATION BETWEEN MIGRAINE AND CARDIOVASCULAR DISEASE AND FINDINGS OF PATHOLOGICAL VASOREACTIVITY AND ENDOTHELIAL DYSFUNCTION. TRIPTANS AND CALCITONIN GENE-RELATED PEPTIDE RECEPTOR ANTAGONISTS SHOW ONLY A RELATIVE MIGRAINE-SPECIFIC ACTION; UP TO 30% OF PATIENTS ARE NONRESPONDERS. DESPITE A CLEAR GENETIC COMPONENT, THE DISCOVERY OF SPECIFIC GENES FOR COMMON FORMS OF MIGRAINE REMAINS ELUSIVE. ELECTROPHYSIOLOGICAL STUDIES CONSISTENTLY INDICATE A CHARACTERISTIC "DYSHABITUATION" CONCURRING WITH CLINICAL FEATURES OF ALTERED SENSORY PERCEPTION. THE AGE- AND SEX-SPECIFIC PATTERN ALONG WITH THE EFFECT OF EXTERNAL FACTORS ON THE COURSE OF MIGRAINE ARGUE IN FAVOR OF THE INVOLVEMENT OF EPIGENETIC MECHANISMS. KNOWLEDGE ABOUT MIGRAINE IS STILL LIMITED, WHICH HAMPERS A DEFINITION. 2009 11 4914 24 PAIN VULNERABILITY: A NEUROBIOLOGICAL PERSPECTIVE. THERE ARE MANY KNOWN RISK FACTORS FOR CHRONIC PAIN CONDITIONS, YET THE BIOLOGICAL UNDERPINNINGS THAT LINK THESE FACTORS TO ABNORMAL PROCESSING OF PAINFUL SIGNALS ARE ONLY JUST BEGINNING TO BE EXPLORED. THIS REVIEW WILL DISCUSS THE POTENTIAL MECHANISMS THAT HAVE BEEN PROPOSED TO UNDERLIE VULNERABILITY AND RESILIENCE TOWARD DEVELOPING CHRONIC PAIN. PARTICULAR FOCUS WILL BE GIVEN TO GENETIC AND EPIGENETIC PROCESSES, PRIMING EFFECTS ON A CELLULAR LEVEL, AND ALTERATIONS IN BRAIN NETWORKS CONCERNED WITH REWARD, MOTIVATION/LEARNING AND DESCENDING MODULATORY CONTROL. ALTHOUGH RESEARCH IN THIS AREA IS STILL IN ITS INFANCY, A BETTER UNDERSTANDING OF HOW PAIN VULNERABILITY EMERGES HAS THE POTENTIAL TO HELP IDENTIFY INDIVIDUALS AT RISK AND MAY OPEN UP NEW THERAPEUTIC AVENUES. 2014 12 1248 26 CURRENT EVIDENCE FOR BIOLOGICAL BIOMARKERS AND MECHANISMS UNDERLYING ACUTE TO CHRONIC PAIN TRANSITION ACROSS THE PEDIATRIC AGE SPECTRUM. CHRONIC PAIN IS HIGHLY PREVALENT IN THE PEDIATRIC POPULATION. MANY FACTORS ARE INVOLVED IN THE TRANSITION FROM ACUTE TO CHRONIC PAIN. CURRENTLY, THERE ARE CONCEPTUAL MODELS PROPOSED, BUT THEY LACK A MECHANISTICALLY SOUND INTEGRATED THEORY CONSIDERING THE STAGES OF CHILD DEVELOPMENT. OBJECTIVE BIOMARKERS ARE CRITICALLY NEEDED FOR THE DIAGNOSIS, RISK STRATIFICATION, AND PROGNOSIS OF THE PATHOLOGICAL STAGES OF PAIN CHRONIFICATION. IN THIS ARTICLE, WE SUMMARIZE THE CURRENT EVIDENCE ON MECHANISMS AND BIOMARKERS OF ACUTE TO CHRONIC PAIN TRANSITIONS IN INFANTS AND CHILDREN THROUGH THE DEVELOPMENTAL LENS. THE GOAL IS TO IDENTIFY GAPS AND OUTLINE FUTURE DIRECTIONS FOR BASIC AND CLINICAL RESEARCH TOWARD A DEVELOPMENTALLY INFORMED THEORY OF PAIN CHRONIFICATION IN THE PEDIATRIC POPULATION. AT THE OUTSET, THE IMPORTANCE OF OBJECTIVE BIOMARKERS FOR CHRONIFICATION OF PAIN IN CHILDREN IS OUTLINED, FOLLOWED BY A SUMMARY OF THE CURRENT EVIDENCE ON THE MECHANISMS OF ACUTE TO CHRONIC PAIN TRANSITION IN ADULTS, IN ORDER TO CONTRAST WITH THE DEVELOPMENTAL MECHANISMS OF PAIN CHRONIFICATION IN THE PEDIATRIC POPULATION. EVIDENCE IS PRESENTED TO SHOW THAT CHRONIC PAIN MAY HAVE ITS ORIGIN FROM INSULTS EARLY IN LIFE, WHICH PRIME THE CHILD FOR THE DEVELOPMENT OF CHRONIC PAIN IN LATER LIFE. FURTHERMORE, AVAILABLE GENETIC, EPIGENETIC, PSYCHOPHYSICAL, ELECTROPHYSIOLOGICAL, NEUROIMAGING, NEUROIMMUNE, AND SEX MECHANISMS ARE DESCRIBED IN INFANTS AND OLDER CHILDREN. IN CONCLUSION, FUTURE DIRECTIONS ARE DISCUSSED WITH A FOCUS ON RESEARCH GAPS, TRANSLATIONAL AND CLINICAL IMPLICATIONS. UTILIZATION OF DEVELOPMENTAL MECHANISMS FRAMEWORK TO INFORM CLINICAL DECISION-MAKING AND STRATEGIES FOR PREVENTION AND MANAGEMENT OF ACUTE TO CHRONIC PAIN TRANSITIONS IN CHILDREN, IS HIGHLIGHTED. 2023 13 6260 24 THE MOLECULAR NEUROBIOLOGY OF CHRONIC PAIN-INDUCED DEPRESSION. THE INCREASING NUMBER OF INDIVIDUALS WITH COMORBIDITIES POSES AN URGENT NEED TO IMPROVE THE MANAGEMENT OF PATIENTS WITH MULTIPLE CO-EXISTING DISEASES. AMONG THESE COMORBIDITIES, CHRONIC PAIN AND MOOD DISORDERS, TWO LONG-LASTING DISABLING CONDITIONS THAT SIGNIFICANTLY REDUCE THE QUALITY OF LIFE, COULD BE CITED FIRST. THE RECENT DEVELOPMENT OF ANIMAL MODELS ACCELERATED THE STUDIES FOCUSING ON THE UNDERLYING MECHANISMS OF THE CHRONIC PAIN AND DEPRESSION/ANXIETY COMORBIDITY. THIS REVIEW PROVIDES AN OVERVIEW OF CLINICAL AND PRE-CLINICAL STUDIES PERFORMED OVER THE PAST TWO DECADES ADDRESSING THE MOLECULAR ASPECTS OF THE COMORBID RELATIONSHIP OF CHRONIC PAIN AND DEPRESSION. WE THUS FOCUSED ON THE STUDIES THAT INVESTIGATED THE MOLECULAR CHARACTERISTICS OF THE COMORBID RELATIONSHIP BETWEEN CHRONIC PAIN AND MOOD DISORDERS, ESPECIALLY MAJOR DEPRESSIVE DISORDERS, FROM THE GENETIC AND EPIGENETIC POINT OF VIEW TO KEY NEUROMODULATORS WHICH HAVE BEEN SHOWN TO PLAY AN IMPORTANT ROLE IN THIS COMORBIDITY. 2019 14 1111 29 COMMON MICRORNAS IN EPILEPSY AND MIGRAINE: THEIR POSSIBILITY AS CANDIDATES FOR BIOMARKERS AND THERAPEUTIC TARGETS DURING COMORBID ONSET OF BOTH CONDITIONS. EPILEPSY AND MIGRAINE ARE CHRONIC NEUROLOGICAL DISORDERS WITH SHARED CLINICAL AS WELL AS PATHOPHYSIOLOGICAL MECHANISMS. EPILEPTIC PATIENTS ARE AT A HIGHER RISK OF DEVELOPING MIGRAINE COMPARED TO NORMAL INDIVIDUALS AND VICE VERSA. SEVERAL GENETIC AND ENVIRONMENTAL RISK FACTORS HAVE BEEN REPORTED TO BE ASSOCIATED WITH THE DEVELOPMENT OF BOTH DISEASES. PREVIOUS STUDIES HAVE ALREADY ESTABLISHED STANDARD GENETIC MARKERS INVOLVED IN VARIOUS PATHWAYS IMPLICATED IN THE PATHOGENESIS OF BOTH THESE COMORBID CONDITIONS. IN ADDITION TO GENETIC MARKERS, EPIGENETIC MARKERS HAVE ALSO BEEN FOUND TO BE INVOLVED IN THE PATHOGENESIS OF EPILEPSY AND MIGRAINE. AMONG THE EPIGENETIC MARKERS, MIRNAS HAVE BEEN EXPLORED AT LENGTH AND HAVE EMERGED AS SIGNIFICANT PLAYERS IN REGULATING THE EXPRESSION OF THEIR TARGET GENES. MIRNAS LIKE MIR-22, MIR-34A, MIR-155, MIR-211, AND LET-7B PLAY A SIGNIFICANT ROLE IN NEURONAL DIFFERENTIATION AND SEEM TO BE ASSOCIATED WITH EPILEPSY AND MIGRAINE AS COMORBID CONDITIONS. HOWEVER, THE EXACT SHARED MECHANISMS UNDERLYING THE ROLE OF THESE MIRNAS IN THESE COMORBID CONDITIONS ARE STILL UNCLEAR. THE CURRENT REVIEW HAS BEEN COMPILED WITH AN AIM TO EXPLORE COMMON MICRORNAS TARGETING THE GENES INVOLVED IN SHARED MOLECULAR PATHWAYS LEADING TO EPILEPSY AND MIGRAINE AS COMORBID CONDITIONS. THE NEW CLASS OF NCRNAS, I.E., TRNA TRANSFER FRAGMENTS, ARE ALSO DISCUSSED. IN ADDITION, THEIR ROLE AS POTENTIAL BIOMARKERS AND THERAPEUTIC TARGETS HAS ALSO BEEN EVALUATED. HOWEVER, LIMITATIONS EXIST, AND BASED ON THE CURRENT LITERATURE AVAILABLE, ONLY A FEW MICRORNAS SEEM TO BE INVOLVED IN THE PATHOGENESIS OF BOTH THESE DISORDERS. 2023 15 2526 28 EPIGENETICS APPLIED TO PSYCHIATRY: CLINICAL OPPORTUNITIES AND FUTURE CHALLENGES. PSYCHIATRIC DISORDERS ARE CLINICALLY HETEROGENEOUS AND DEBILITATING CHRONIC DISEASES RESULTING FROM A COMPLEX INTERPLAY BETWEEN GENE VARIANTS AND ENVIRONMENTAL FACTORS. EPIGENETIC PROCESSES, SUCH AS DNA METHYLATION AND HISTONE POSTTRANSLATIONAL MODIFICATIONS, INSTRUCT THE CELL/TISSUE TO CORRECTLY INTERPRET EXTERNAL SIGNALS AND ADJUST ITS FUNCTIONS ACCORDINGLY. GIVEN THAT EPIGENETIC MODIFICATIONS ARE SENSITIVE TO ENVIRONMENT, STABLE, AND REVERSIBLE, EPIGENETIC STUDIES IN PSYCHIATRY COULD REPRESENT A PROMISING APPROACH TO BETTER UNDERSTANDING AND TREATING DISEASE. IN THE PRESENT REVIEW, WE AIM TO DISCUSS THE CLINICAL OPPORTUNITIES AND CHALLENGES ARISING FROM THE EPIGENETIC RESEARCH IN PSYCHIATRY. USING SELECTED EXAMPLES, WE FIRST RECAPITULATE KEY FINDINGS SUPPORTING THE ROLE OF ADVERSE LIFE EVENTS, ALONE OR IN COMBINATION WITH GENETIC RISK, IN EPIGENETIC PROGRAMMING OF NEUROPSYCHIATRIC SYSTEMS. EPIGENETIC STUDIES FURTHER REPORT ENCOURAGING FINDINGS ABOUT THE USE OF METHYLATION CHANGES AS DIAGNOSTIC MARKERS OF DISEASE PHENOTYPE AND PREDICTIVE TOOLS OF PROGRESSION AND RESPONSE TO TREATMENT. THEN WE DISCUSS THE POTENTIAL OF USING TARGETED EPIGENETIC PHARMACOTHERAPY, COMBINED WITH PSYCHOSOCIAL INTERVENTIONS, FOR FUTURE PERSONALIZED MEDICINE FOR PATIENTS. FINALLY, WE REVIEW THE METHODOLOGICAL LIMITATIONS THAT COULD HINDER INTERPRETATION OF EPIGENETIC DATA IN PSYCHIATRY. THEY MAINLY ARISE FROM HETEROGENEITY AT THE INDIVIDUAL AND TISSUE LEVEL AND REQUIRE FUTURE STRATEGIES IN ORDER TO REINFORCE THE BIOLOGICAL RELEVANCE OF EPIGENETIC DATA AND ITS TRANSLATIONAL USE IN PSYCHIATRY. OVERALL, WE SUGGEST THAT EPIGENETICS COULD PROVIDE NEW INSIGHTS INTO A MORE COMPREHENSIVE INTERPRETATION OF MENTAL ILLNESS AND MIGHT EVENTUALLY IMPROVE THE NOSOLOGY, TREATMENT, AND PREVENTION OF PSYCHIATRIC DISORDERS. 2018 16 2404 26 EPIGENETIC RESEARCH IN MULTIPLE SCLEROSIS: PROGRESS, CHALLENGES, AND OPPORTUNITIES. MULTIPLE SCLEROSIS (MS) IS A CHRONIC INFLAMMATORY AND DEMYELINATING DISEASE OF THE CENTRAL NERVOUS SYSTEM. MS LIKELY RESULTS FROM A COMPLEX INTERPLAY BETWEEN PREDISPOSING CAUSAL GENE VARIANTS (THE STRONGEST INFLUENCE COMING FROM HLA CLASS II LOCUS) AND ENVIRONMENTAL RISK FACTORS SUCH AS SMOKING, INFECTIOUS MONONUCLEOSIS, AND LACK OF SUN EXPOSURE/VITAMIN D. HOWEVER, LITTLE IS KNOWN ABOUT THE MECHANISMS UNDERLYING MS DEVELOPMENT AND PROGRESSION. MOREOVER, THE CLINICAL HETEROGENEITY AND VARIABLE RESPONSE TO TREATMENT REPRESENT ADDITIONAL CHALLENGES TO A COMPREHENSIVE UNDERSTANDING AND EFFICIENT TREATMENT OF DISEASE. EPIGENETIC PROCESSES, SUCH AS DNA METHYLATION AND HISTONE POSTTRANSLATIONAL MODIFICATIONS, INTEGRATE INFLUENCES FROM THE GENES AND THE ENVIRONMENT TO REGULATE GENE EXPRESSION ACCORDINGLY. STUDYING EPIGENETIC MODIFICATIONS, WHICH ARE STABLE AND REVERSIBLE, MAY PROVIDE AN ALTERNATIVE APPROACH TO BETTER UNDERSTAND AND MANAGE DISEASE. WE HERE AIM TO REVIEW FINDINGS FROM EPIGENETIC STUDIES IN MS AND FURTHER DISCUSS THE CHALLENGES AND CLINICAL OPPORTUNITIES ARISING FROM EPIGENETIC RESEARCH, MANY OF WHICH APPLY TO OTHER DISEASES WITH SIMILAR COMPLEX ETIOLOGY. A GROWING BODY OF EVIDENCE SUPPORTS A ROLE OF EPIGENETIC PROCESSES IN THE MECHANISMS UNDERLYING IMMUNE PATHOGENESIS AND NERVOUS SYSTEM DYSFUNCTION IN MS. HOWEVER, DISPARITIES BETWEEN STUDIES SHED LIGHT ON THE NEED TO CONSIDER POSSIBLE CONFOUNDERS AND METHODOLOGICAL LIMITATIONS FOR A BETTER INTERPRETATION OF THE DATA. NEVERTHELESS, TRANSLATIONAL USE OF EPIGENETICS MIGHT OFFER NEW OPPORTUNITIES IN EPIGENETIC-BASED DIAGNOSTICS AND THERAPEUTIC TOOLS FOR A PERSONALIZED CARE OF MS PATIENTS. 2017 17 5926 27 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 18 2231 28 EPIGENETIC MODIFICATIONS OF MAJOR DEPRESSIVE DISORDER. MAJOR DEPRESSIVE DISORDER (MDD) IS A CHRONIC DISEASE WHOSE NEUROLOGICAL BASIS AND PATHOPHYSIOLOGY REMAIN POORLY UNDERSTOOD. INITIALLY, IT WAS PROPOSED THAT GENETIC VARIATIONS WERE RESPONSIBLE FOR THE DEVELOPMENT OF THIS DISEASE. NEVERTHELESS, SEVERAL STUDIES WITHIN THE LAST DECADE HAVE PROVIDED EVIDENCE SUGGESTING THAT ENVIRONMENTAL FACTORS PLAY AN IMPORTANT ROLE IN MDD PATHOPHYSIOLOGY. ALTERATIONS IN EPIGENETICS MECHANISM, SUCH AS DNA METHYLATION, HISTONE MODIFICATION AND MICRORNA EXPRESSION COULD FAVOR MDD ADVANCE IN RESPONSE TO STRESSFUL EXPERIENCES AND ENVIRONMENTAL FACTORS. THE AIM OF THIS REVIEW IS TO DESCRIBE GENETIC ALTERATIONS, AND PARTICULARLY ALTERED EPIGENETIC MECHANISMS, THAT COULD BE DETERMINANTS FOR MDD PROGRESS, AND HOW THESE ALTERATIONS MAY ARISE AS USEFUL SCREENING, DIAGNOSIS AND TREATMENT MONITORING BIOMARKERS OF DEPRESSIVE DISORDERS. 2016 19 2523 35 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 20 6866 31 [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