1 6790 86 [DNA METHYLATION ANALYSIS IN ENVIRONMENTAL AND OCCUPATIONAL CANCER RESEARCH]. THE PRESENT PAPER REVIEWS RECENT LABORATORY METHODS AND EXPERIMENTAL EVIDENCE CONCERNING EPIGENETIC BIOMARKERS INVOLVED IN CARCINOGENESIS MECHANISMS. WE INTRODUCE DNA METHYLATION AND ITS ROLE IN GENE EXPRESSION CONTROL. DNA METHYLATION ANALYSIS MAY ALLOW TO IDENTIFY EARLY CHANGES LEADING TO CANCER AND OTHER CHRONIC DISEASES. WE DESCRIBE HERE STRATEGIES FOR LABORATORY ANALYSES AND THEIR POSSIBLE APPLICATIONS. WE EXAMINE RESULTS FROM RECENT EXPERIMENTAL STUDIES SUGGESTING THAT THE EFFECTS OF CERTAIN OCCUPATIONAL AGENTS ARE MEDIATED BY ALTERATIONS IN DNA METHYLATION. PLANNING AND CONDUCTING INVESTIGATIONS ON EXPOSED HUMAN SUBJECTS WILL ALLOW TO VERIFY WHETHER DNA METHYLATION CHANGES IDENTIFIED IN ANIMAL AND IN-VITRO STUDIES MAY BE USED AS EARLY-EFFECT AND SUSCEPTIBILITY BIOMARKERS. DNA METHYLATION ANALYSIS HAS THE POTENTIAL FOR FUTURE APPLICATIONS IN RISK ASSESSMENT AND PREVENTION PROGRAMS CONDUCTED ON SUBJECTS EXPOSED TO HUMAN CARCINOGENS. 2005 2 1014 25 CIGARETTE SMOKING AND DNA METHYLATION. DNA METHYLATION IS THE MOST STUDIED EPIGENETIC MODIFICATION, CAPABLE OF CONTROLLING GENE EXPRESSION IN THE CONTEXTS OF NORMAL TRAITS OR DISEASES. IT IS HIGHLY DYNAMIC DURING EARLY EMBRYOGENESIS AND REMAINS RELATIVELY STABLE THROUGHOUT LIFE, AND SUCH PATTERNS ARE INTRICATELY RELATED TO HUMAN DEVELOPMENT. DNA METHYLATION IS A QUANTITATIVE TRAIT DETERMINED BY A COMPLEX INTERPLAY OF GENETIC AND ENVIRONMENTAL FACTORS. GENETIC VARIANTS AT A SPECIFIC LOCUS CAN INFLUENCE BOTH REGIONAL AND DISTANT DNA METHYLATION. THE ENVIRONMENT CAN HAVE VARYING EFFECTS ON DNA METHYLATION DEPENDING ON WHEN THE EXPOSURE OCCURS, SUCH AS DURING PRENATAL LIFE OR DURING ADULTHOOD. IN PARTICULAR, CIGARETTE SMOKING IN THE CONTEXT OF BOTH CURRENT SMOKING AND PRENATAL EXPOSURE IS A STRONG MODIFIER OF DNA METHYLATION. EPIGENOME-WIDE ASSOCIATION STUDIES HAVE UNCOVERED CANDIDATE GENES ASSOCIATED WITH CIGARETTE SMOKING THAT HAVE BIOLOGICALLY RELEVANT FUNCTIONS IN THE ETIOLOGY OF SMOKING-RELATED DISEASES. AS SUCH, DNA METHYLATION IS A POTENTIAL MECHANISTIC LINK BETWEEN CURRENT SMOKING AND CANCER, AS WELL AS PRENATAL CIGARETTE-SMOKE EXPOSURE AND THE DEVELOPMENT OF ADULT CHRONIC DISEASES. 2013 3 396 29 AN UPDATE ON EPIGENETICS AND CHILDHOOD RESPIRATORY DISEASES. EPIGENETIC MECHANISMS, DEFINED AS CHANGES IN PHENOTYPE OR GENE EXPRESSION CAUSED BY MECHANISMS OTHER THAN CHANGES IN THE UNDERLYING DNA SEQUENCE, HAVE BEEN PROPOSED TO CONSTITUTE A LINK BETWEEN GENETIC AND ENVIRONMENTAL FACTORS THAT AFFECT COMPLEX DISEASES. RECENT STUDIES SHOW THAT DNA METHYLATION, ONE OF THE KEY EPIGENETIC MECHANISMS, IS ALTERED IN CHILDREN EXPOSED TO AIR POLLUTANTS AND ENVIRONMENTAL TOBACCO SMOKE EARLY IN LIFE. SEVERAL CANDIDATE GENE STUDIES ON EPIGENETICS HAVE BEEN PUBLISHED TO DATE, BUT IT IS ONLY RECENTLY THAT GLOBAL METHYLATION ANALYSES HAVE BEEN PERFORMED FOR RESPIRATORY DISORDERS SUCH AS ASTHMA AND CHRONIC OBSTRUCTIVE PULMONARY DISEASE. HOWEVER, LARGE-SCALE STUDIES WITH ADEQUATE POWER ARE YET TO BE PRESENTED IN CHILDREN, AND IMPLICATIONS FOR CLINICAL USE REMAIN TO BE EVALUATED. IN THIS REVIEW, WE SUMMARIZE THE RECENT ADVANCES IN EPIGENETICS AND RESPIRATORY DISORDERS IN CHILDREN, WITH A MAIN FOCUS ON METHODOLOGICAL CHALLENGES AND ANALYSES RELATED TO PHENOTYPE AND EXPOSURE USING GLOBAL METHYLATION APPROACHES. 2014 4 1546 25 DNA METHYLATION IN NASAL EPITHELIUM: STRENGTHS AND LIMITATIONS OF AN EMERGENT BIOMARKER FOR CHILDHOOD ASTHMA. ASTHMA IS ONE OF THE MOST WIDESPREAD CHRONIC RESPIRATORY CONDITIONS. THIS DISEASE PRIMARILY DEVELOPS IN CHILDHOOD AND IS INFLUENCED BY DIFFERENT FACTORS, MAINLY GENETICS AND ENVIRONMENTAL FACTORS. DNA METHYLATION IS AN EPIGENETIC MECHANISM WHICH MAY REPRESENT A BRIDGE BETWEEN THESE TWO FACTORS, PROVIDING A TOOL TO COMPREHEND THE INTERACTION BETWEEN GENETICS AND ENVIRONMENT. MOST EPIDEMIOLOGICAL STUDIES IN THIS FIELD HAVE BEEN CONDUCTED USING BLOOD SAMPLES, ALTHOUGH DNA METHYLATION MARKS IN BLOOD MAY NOT BE RELIABLE FOR DRAWING EXHAUSTIVE CONCLUSIONS ABOUT DNA METHYLATION IN THE AIRWAYS. BECAUSE OF THE ROLE OF NASAL EPITHELIUM IN ASTHMA AND THE TISSUE SPECIFICITY OF DNA METHYLATION, STUDYING THE RELATIONSHIP BETWEEN DNA METHYLATION AND CHILDHOOD ASTHMA MIGHT REVEAL CRUCIAL INFORMATION ABOUT THIS WIDESPREAD RESPIRATORY DISEASE. THE PURPOSE OF THIS REVIEW IS TO DESCRIBE CURRENT FINDINGS IN THIS FIELD OF RESEARCH. WE WILL PRESENT A VIEWPOINT OF SELECTED STUDIES, CONSIDER STRENGTHS AND LIMITATIONS, AND PROPOSE FUTURE RESEARCH IN THIS AREA. 2020 5 1844 32 EFFECTS OF THE LIFESTYLE HABITS IN BREAST CANCER TRANSCRIPTIONAL REGULATION. THROUGH RESEARCH CARRIED OUT IN THE LAST 25 YEARS ABOUT THE BREAST CANCER ETIOLOGY, IT HAS BEEN POSSIBLE TO ESTIMATE THAT LESS THAN 10 % OF PATIENTS WHO ARE DIAGNOSED WITH THE CONDITION ARE CARRIERS OF SOME GERMLINE OR SOMATIC MUTATION. THE CLINICAL REPORTS OF BREAST CANCER PATIENTS WITH HEALTHY TWINS AND THE DEVELOPMENT OF DISEASE IN WOMEN WITHOUT HIGH PENETRANCE MUTATIONS DETECTED, WARN THE PARTICIPATION MORE FACTORS IN THE TRANSFORMATION PROCESS. THE HIGH INCIDENCE OF MAMMARY ADENOCARCINOMA IN THE MODERN WOMAN AND THE URGENT NEED FOR NEW METHODS OF PREVENTION AND EARLY DETECTION HAVE DEMANDED MORE INFORMATION ABOUT THE ROLE THAT ENVIRONMENT AND LIFESTYLE HAVE ON THE TRANSFORMATION OF MAMMARY GLAND EPITHELIAL CELLS. OBESITY, ALCOHOLISM AND SMOKING ARE FACTORS THAT HAVE SHOWN A CLOSE CORRELATION WITH THE RISK OF DEVELOPING BREAST CANCER. AND ALTHOUGH THESE CONDITIONS AFFECT DIFFERENT CELL REGULATION LEVELS, THE STUDY OF ITS EFFECTS IN THE MECHANISMS OF TRANSCRIPTIONAL AND EPIGENETIC REGULATION IS CONSIDERED CRITICAL FOR A BETTER UNDERSTANDING OF THE LOSS OF IDENTITY OF EPITHELIAL CELLS DURING CARCINOGENESIS OF THIS TISSUE. THE MAIN OBJECTIVE OF THIS REVIEW WAS TO ESTABLISH THE IMPORTANCE OF CHANGES OCCURRING TO TRANSCRIPTIONAL LEVEL IN THE MAMMARY GLAND AS A CONSEQUENCE OF ACUTE OR CHRONIC EXPOSURE TO HARMFUL PRODUCTS SUCH AS OBESITY-CAUSING FOODS, ETHANOL AND CIGARETTE SMOKE COMPONENTS. AT ANALYZE THE MAIN STUDIES RELATED TO TOPIC, IT HAS CONCLUDED THAT THE UNDERSTANDING OF EFFECTS CAUSED BY THE LIFESTYLE FACTORS IN PERFORMANCE OF THE TRANSCRIPTIONAL MECHANISMS THAT DETERMINE GENE EXPRESSION OF THE MAMMARY GLAND EPITHELIAL CELLS, MAY HELP EXPLAIN THE DEVELOPMENT OF THIS DISEASE IN WOMEN WITHOUT GENETIC PROPENSITY AND DIFFERENT PHENOTYPIC MANIFESTATIONS OF THIS CANCER TYPE. 2016 6 6013 37 THE APPLICATIONS OF DNA METHYLATION AS A BIOMARKER IN KIDNEY TRANSPLANTATION: A SYSTEMATIC REVIEW. BACKGROUND: ALTHOUGH KIDNEY TRANSPLANTATION IMPROVES PATIENT SURVIVAL AND QUALITY OF LIFE, LONG-TERM RESULTS ARE HAMPERED BY BOTH IMMUNE- AND NON-IMMUNE-MEDIATED COMPLICATIONS. CURRENT BIOMARKERS OF POST-TRANSPLANT COMPLICATIONS, SUCH AS ALLOGRAFT REJECTION, CHRONIC RENAL ALLOGRAFT DYSFUNCTION, AND CUTANEOUS SQUAMOUS CELL CARCINOMA, HAVE A SUBOPTIMAL PREDICTIVE VALUE. DNA METHYLATION IS AN EPIGENETIC MODIFICATION THAT DIRECTLY AFFECTS GENE EXPRESSION AND PLAYS AN IMPORTANT ROLE IN PROCESSES SUCH AS ISCHEMIA/REPERFUSION INJURY, FIBROSIS, AND ALLOREACTIVE IMMUNE RESPONSE. NOVEL TECHNIQUES CAN QUICKLY ASSESS THE DNA METHYLATION STATUS OF MULTIPLE LOCI IN DIFFERENT CELL TYPES, ALLOWING A DEEP AND INTERESTING STUDY OF CELLS' ACTIVITY AND FUNCTION. THEREFORE, DNA METHYLATION HAS THE POTENTIAL TO BECOME AN IMPORTANT BIOMARKER FOR PREDICTION AND MONITORING IN KIDNEY TRANSPLANTATION. PURPOSE OF THE STUDY: THE AIM OF THIS STUDY WAS TO EVALUATE THE ROLE OF DNA METHYLATION AS A POTENTIAL BIOMARKER OF GRAFT SURVIVAL AND COMPLICATIONS DEVELOPMENT IN KIDNEY TRANSPLANTATION. MATERIAL AND METHODS: A SYSTEMATIC REVIEW OF SEVERAL DATABASES HAS BEEN CONDUCTED. THE NEWCASTLE-OTTAWA SCALE AND THE JADAD SCALE HAVE BEEN USED TO ASSESS THE RISK OF BIAS FOR OBSERVATIONAL AND RANDOMIZED STUDIES, RESPECTIVELY. RESULTS: TWENTY ARTICLES REPORTING ON DNA METHYLATION AS A BIOMARKER FOR KIDNEY TRANSPLANTATION WERE INCLUDED, ALL USING DNA METHYLATION FOR PREDICTION AND MONITORING. DNA METHYLATION PATTERN ALTERATIONS IN CELLS ISOLATED FROM DIFFERENT TISSUES, SUCH AS KIDNEY BIOPSIES, URINE, AND BLOOD, HAVE BEEN ASSOCIATED WITH ISCHEMIA-REPERFUSION INJURY AND CHRONIC RENAL ALLOGRAFT DYSFUNCTION. THESE ALTERATIONS OCCURRED IN DIFFERENT AND SPECIFIC LOCI. DNA METHYLATION STATUS HAS ALSO PROVED TO BE IMPORTANT FOR IMMUNE RESPONSE MODULATION, HAVING A CRUCIAL ROLE IN REGULATORY T CELL DEFINITION AND ACTIVITY. RESEARCH ALSO FOCUSED ON A BETTER UNDERSTANDING OF THE ROLE OF THIS EPIGENETIC MODIFICATION ASSESSMENT FOR REGULATORY T CELLS ISOLATION AND EXPANSION FOR FUTURE TOLERANCE INDUCTION-ORIENTED THERAPIES. CONCLUSIONS: STUDIES INCLUDED IN THIS REVIEW ARE HETEROGENEOUS IN STUDY DESIGN, BIOLOGICAL SAMPLES, AND OUTCOME. MORE COORDINATED INVESTIGATIONS ARE NEEDED TO AFFIRM DNA METHYLATION AS A CLINICALLY RELEVANT BIOMARKER IMPORTANT FOR PREVENTION, MONITORING, AND INTERVENTION. 2022 7 2483 27 EPIGENETIC VARIATION AND HUMAN DISEASE. CYTOSINE GUANINE DINUCLEOTIDE (CPG) ISLAND METHYLATION IS A KNOWN MECHANISM OF EPIGENETIC INHERITANCE IN POSTMEIOTIC CELLS. THROUGH ASSOCIATED CHROMATIN CHANGES AND SILENCING, SUCH EPIGENETIC STATES CAN INFLUENCE CELLULAR PHYSIOLOGY AND AFFECT DISEASE RISK AND SEVERITY. OUR STUDIES OF CPG ISLAND METHYLATION IN NORMAL COLORECTAL MUCOSA REVEALED PROGRESSIVE AGE-RELATED INCREASES AT MULTIPLE GENE LOCI, SUGGESTING GENOME-WIDE MOLECULAR ALTERATIONS WITH POTENTIAL TO SILENCE GENE EXPRESSION. HOWEVER, THERE WAS CONSIDERABLE VARIATION IN THE DEGREE OF METHYLATION AMONG INDIVIDUALS OF COMPARABLE AGES. SUCH VARIATION COULD BE RELATED TO GENETIC FACTORS, LIFESTYLE, OR ENVIRONMENTAL EXPOSURES. STUDIES IN ULCERATIVE COLITIS AND HEPATOCELLULAR CIRRHOSIS AND NEOPLASIA REVEALED THAT CHRONIC INFLAMMATORY STATES ARE ACCOMPANIED BY MARKED INCREASES IN CPG ISLAND METHYLATION IN NORMAL-APPEARING TISSUES, CONFIRMING THE HYPOTHESIS THAT PROINFLAMMATORY EXPOSURES COULD ACCOUNT FOR PART OF THE EPIGENETIC VARIATION IN HUMAN POPULATIONS. PRELIMINARY DATA ALSO SUGGEST POTENTIAL INFLUENCES OF LIFESTYLE AND EXPOSURE FACTORS ON CPG ISLAND METHYLATION. IT IS SUGGESTED THAT EPIGENETIC VARIATION RELATED TO AGING, LIFESTYLE, EXPOSURES AND POSSIBLY GENETIC FACTORS, IS ONE OF THE MODULATORS OF ACQUIRED, AGE-RELATED HUMAN DISEASES, INCLUDING NEOPLASIA. 2002 8 2507 33 EPIGENETICS AND OBESITY: THE DEVIL IS IN THE DETAILS. OBESITY IS A COMPLEX DISEASE WITH MULTIPLE WELL-DEFINED RISK FACTORS. NEVERTHELESS, SUSCEPTIBILITY TO OBESITY AND ITS SEQUELAE WITHIN OBESOGENIC ENVIRONMENTS VARIES GREATLY FROM ONE PERSON TO THE NEXT, SUGGESTING A ROLE FOR GENE X ENVIRONMENT INTERACTIONS IN THE ETIOLOGY OF THE DISORDER. EPIGENETIC REGULATION OF THE HUMAN GENOME PROVIDES A PUTATIVE MECHANISM BY WHICH SPECIFIC ENVIRONMENTAL EXPOSURES CONVEY RISK FOR OBESITY AND OTHER HUMAN DISEASES AND IS ONE POSSIBLE MECHANISM THAT UNDERLIES THE GENE X ENVIRONMENT/TREATMENT INTERACTIONS OBSERVED IN EPIDEMIOLOGICAL STUDIES AND CLINICAL TRIALS. A STUDY PUBLISHED IN BMC MEDICINE THIS MONTH BY WANG ET AL. REPORTS ON AN EXAMINATION OF DNA METHYLATION IN PERIPHERAL BLOOD LEUKOCYTES OF LEAN AND OBESE ADOLESCENTS, COMPARING METHYLATION PATTERNS BETWEEN THE TWO GROUPS. THE AUTHORS IDENTIFIED TWO GENES THAT WERE DIFFERENTIALLY METHYLATED, BOTH OF WHICH HAVE ROLES IN IMMUNE FUNCTION. HERE WE OVERVIEW THE FINDINGS FROM THIS STUDY IN THE CONTEXT OF THOSE EMERGING FROM OTHER RECENT GENETIC AND EPIGENETIC STUDIES, DISCUSS THE STRENGTHS AND WEAKNESSES OF THE STUDY AND SPECULATE ON THE FUTURE OF EPIGENETICS IN CHRONIC DISEASE RESEARCH. 2010 9 528 30 ASTHMA EPIGENETICS. ASTHMA IS THE MOST COMMON CHRONIC DISEASE OF CHILDHOOD, AND A GROWING BODY OF EVIDENCE INDICATES THAT EPIGENETIC VARIATIONS MAY MEDIATE THE EFFECTS OF ENVIRONMENTAL EXPOSURES ON THE DEVELOPMENT AND NATURAL HISTORY OF ASTHMA. EPIGENETICS IS THE STUDY OF MITOTICALLY OR MEIOTICALLY HERITABLE CHANGES IN GENE EXPRESSION THAT OCCUR WITHOUT DIRECTLY ALTERING THE DNA SEQUENCE. DNA METHYLATION, HISTONE MODIFICATIONS AND MICRORNAS ARE MAJOR EPIGENETIC VARIATIONS IN HUMANS THAT ARE CURRENTLY BEING INVESTIGATED FOR ASTHMA ETIOLOGY AND NATURAL HISTORY. DNA METHYLATION RESULTS FROM ADDITION OF A METHYL GROUP TO THE 5 POSITION OF A CYTOSINE RING AND OCCURS ALMOST EXCLUSIVELY ON A CYTOSINE IN A CPG DINUCLEOTIDE. HISTONE MODIFICATIONS INVOLVE POSTTRANSLATIONAL MODIFICATIONS SUCH AS ACETYLATION, METHYLATION, PHOSPHORYLATION AND UBIQUITINATION ON THE TAILS OF CORE HISTONES. MICRORNAS ARE SHORT ~22 NUCLEOTIDE LONG, NON-CODING, SINGLE-STRANDED RNAS THAT BINDS TO COMPLEMENTARY SEQUENCES IN THE TARGET MRNAS, USUALLY RESULTING IN GENE SILENCING. WHILE MANY STUDIES HAVE DOCUMENTED RELATIONSHIPS OF ENVIRONMENTAL EXPOSURES THAT HAVE BEEN IMPLICATED IN ASTHMA ETIOLOGY WITH EPIGENETIC ALTERATIONS, TO DATE, FEW STUDIES HAVE DIRECTLY LINKED EPIGENETIC VARIATIONS WITH ASTHMA DEVELOPMENT. THERE ARE SEVERAL METHODOLOGICAL CHALLENGES IN STUDYING THE EPIGENETICS OF ASTHMA. IN THIS CHAPTER, THE INFLUENCE OF EPIGENETIC VARIATIONS ON ASTHMA PATHOPHYSIOLOGY, METHODOLOGICAL CONCERNS IN CONDUCTING EPIGENETIC RESEARCH AND FUTURE DIRECTION OF ASTHMA EPIGENETICS RESEARCH ARE DISCUSSED. 2014 10 4531 34 MULTILAYER-OMICS ANALYSES OF HUMAN CANCERS: EXPLORATION OF BIOMARKERS AND DRUG TARGETS BASED ON THE ACTIVITIES OF THE INTERNATIONAL HUMAN EPIGENOME CONSORTIUM. EPIGENETIC ALTERATIONS CONSISTING MAINLY OF DNA METHYLATION ALTERATIONS AND HISTONE MODIFICATION ALTERATIONS ARE FREQUENTLY OBSERVED IN CANCERS ASSOCIATED WITH CHRONIC INFLAMMATION AND/OR PERSISTENT INFECTION WITH VIRUSES OR OTHER PATHOGENIC MICROORGANISMS, OR WITH CIGARETTE SMOKING. ACCUMULATING EVIDENCE SUGGESTS THAT ALTERATIONS OF DNA METHYLATION ARE INVOLVED EVEN IN THE EARLY AND PRECANCEROUS STAGES. ON THE OTHER HAND, IN PATIENTS WITH CANCERS, ABERRANT DNA METHYLATION IS FREQUENTLY ASSOCIATED WITH TUMOR AGGRESSIVENESS AND POOR PATIENT OUTCOME. RECENTLY, EPIGENOME ALTERATIONS HAVE BEEN ATTRACTING A GREAT DEAL OF ATTENTION FROM RESEARCHERS WHO ARE FOCUSING ON NOT ONLY CANCERS BUT ALSO NEURONAL, IMMUNE AND METABOLIC DISORDERS. IN ORDER TO ACCURATELY IDENTIFY DISEASE-SPECIFIC EPIGENOME PROFILES THAT COULD BE POTENTIALLY APPLICABLE FOR DISEASE PREVENTION, DIAGNOSIS AND THERAPY, STRICT COMPARISON WITH STANDARD EPIGENOME PROFILES OF NORMAL TISSUES IS INDISPENSABLE. HOWEVER, EPIGENOME MECHANISMS SHOW HETEROGENEITY AMONG TISSUES AND CELL LINEAGES. THEREFORE, IT IS NOT EASY TO OBTAIN A COMPREHENSIVE PICTURE OF STANDARD EPIGENOME PROFILES OF NORMAL TISSUES. IN 2010, THE INTERNATIONAL HUMAN EPIGENOME CONSORTIUM (IHEC) WAS ESTABLISHED TO COORDINATE THE PRODUCTION OF REFERENCE MAPS OF HUMAN EPIGENOMES FOR KEY CELLULAR STATES. IN ORDER TO GAIN SUBSTANTIAL COVERAGE OF THE HUMAN EPIGENOME, THE IHEC HAS SET AN AMBITIOUS GOAL TO DECIPHER AT LEAST 1000 EPIGENOMES WITHIN THE NEXT 7-10 YEARS. WE CONSIDER THAT PATHWAY ANALYSIS USING GENES SHOWING MULTILAYER-OMICS ABNORMALITIES, INCLUDING GENOME, EPIGENOME, TRANSCRIPTOME, PROTEOME AND METABOLOME ABNORMALITIES, MAY BE USEFUL FOR ELUCIDATING THE MOLECULAR BACKGROUND OF PATHOGENESIS AND FOR EXPLORING POSSIBLE THERAPEUTIC TARGETS FOR EACH DISEASE. 2014 11 2523 36 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 12 738 30 CANCER SUSCEPTIBILITY: EPIGENETIC MANIFESTATION OF ENVIRONMENTAL EXPOSURES. CANCER IS A DISEASE THAT RESULTS FROM BOTH GENETIC AND EPIGENETIC CHANGES. DISCORDANT PHENOTYPES AND VARYING INCIDENCES OF COMPLEX DISEASES SUCH AS CANCER IN MONOZYGOTIC TWINS AS WELL AS GENETICALLY IDENTICAL LABORATORY ANIMALS HAVE LONG BEEN ATTRIBUTED TO DIFFERENCES IN ENVIRONMENTAL EXPOSURES. ACCUMULATING EVIDENCE INDICATES, HOWEVER, THAT DISPARITIES IN GENE EXPRESSION RESULTING FROM VARIABLE MODIFICATIONS IN DNA METHYLATION AND CHROMATIN STRUCTURE IN RESPONSE TO THE ENVIRONMENT ALSO PLAY A ROLE IN DIFFERENTIAL SUSCEPTIBILITY TO DISEASE. DESPITE A GROWING CONSENSUS ON THE IMPORTANCE OF EPIGENETICS IN THE ETIOLOGY OF CHRONIC HUMAN DISEASES, THE GENES MOST PRONE TO EPIGENETIC DYSREGULATION ARE INCOMPLETELY DEFINED. MOREOVER, NEITHER THE ENVIRONMENTAL AGENTS MOST STRONGLY AFFECTING THE EPIGENOME NOR THE CRITICAL WINDOWS OF VULNERABILITY TO ENVIRONMENTALLY INDUCED EPIGENETIC ALTERATIONS ARE ADEQUATELY CHARACTERIZED. THESE MAJOR DEFICITS IN KNOWLEDGE MARKEDLY IMPAIR OUR ABILITY TO UNDERSTAND FULLY THE ETIOLOGY OF CANCER AND THE IMPORTANCE OF THE EPIGENOME IN DIAGNOSING AND PREVENTING THIS DEVASTATING DISEASE. 2007 13 6809 25 [EPIGENETICS IN INFLAMMATORY SYSTEMIC DISEASES]. IN ADDITION TO ANALYSIS OF THE GENETIC CODE, IN RECENT YEARS MORE AND MORE STUDIES HAVE CONCENTRATED ON CHANGES IN THE EPIGENETIC CODE. EPIGENETIC MECHANISMS DETERMINE WHICH GENES IN A CELL ARE TRANSCRIBED AND THUS FORM THE PHENOTYPE OF A CELL. THE EPIGENETIC CODE CAN BE CHANGED BY ENVIRONMENTAL INFLUENCES, WHICH ALLOWS CELLS TO ADAPT TO LONGSTANDING CHANGES IN THE ENVIRONMENT. THEREFORE, IT IS FEASIBLE TO ASSUME THAT EPIGENETIC CHANGES ARE THE MOLECULAR BASIS FOR LONG-TERM EFFECTS OF THE ENVIRONMENT ON DISEASE DEVELOPMENT. IN PARTICULAR IN TUMORS AND CHRONIC INFLAMMATORY DISEASES EPIGENETIC CHANGES WERE FOUND TO CORRELATE WITH DISEASE SEVERITY AND PROGRESSION. KNOWLEDGE ABOUT THESE EPIGENETIC CHANGES MIGHT HELP THAT EPIGENETIC MODIFICATIONS CAN BE USED IN THE FUTURE AS BIOMARKERS, PROGNOSTIC FACTORS AND THERAPEUTIC TARGETS. 2014 14 6458 30 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 15 1518 27 DNA METHYLATION AS AN EPIGENETIC MECHANISM IN THE DEVELOPMENT OF MULTIPLE SCLEROSIS. THE EPIGENETIC MECHANISMS OF GENE EXPRESSION REGULATION ARE A GROUP OF THE KEY CELLULAR AND MOLECULAR PATHWAYS THAT LEAD TO INHERITED ALTERATIONS IN GENES' ACTIVITY WITHOUT CHANGING THEIR CODING SEQUENCE. DNA METHYLATION AT THE C5 POSITION OF CYTOSINE IN CPG DINUCLEOTIDES IS AMONGST THE CENTRAL EPIGENETIC MECHANISMS. CURRENTLY, THE NUMBER OF STUDIES THAT ARE DEVOTED TO THE IDENTIFICATION OF METHYLATION PATTERNS SPECIFIC TO MULTIPLE SCLEROSIS (MS), A SEVERE CHRONIC AUTOIMMUNE DISEASE OF THE CENTRAL NERVOUS SYSTEM, IS ON A RAPID RISE. HOWEVER, THE ISSUE OF THE CONTRIBUTION OF DNA METHYLATION TO THE DEVELOPMENT OF THE DIFFERENT CLINICAL PHENOTYPES OF THIS HIGHLY HETEROGENEOUS DISEASE HAS ONLY BEGUN TO ATTRACT THE ATTENTION OF RESEARCHERS. THIS REVIEW SUMMARIZES THE DATA ON THE MOLECULAR MECHANISMS UNDERLYING DNA METHYLATION AND THE MS RISK FACTORS THAT CAN AFFECT THE DNA METHYLATION PROFILE AND, THEREBY, MODULATE THE EXPRESSION OF THE GENES INVOLVED IN THE DISEASE'S PATHOGENESIS. THE FOCUS OF OUR ATTENTION IS CENTERED ON THE ANALYSIS OF THE PUBLISHED DATA ON THE DIFFERENTIAL METHYLATION OF DNA FROM VARIOUS BIOLOGICAL SAMPLES OF MS PATIENTS OBTAINED USING BOTH THE CANDIDATE GENE APPROACH AND HIGH-THROUGHPUT METHODS. 2021 16 1583 36 DNA METHYLATION PROFILES OF BLOOD CELLS ARE DISTINCT BETWEEN EARLY-ONSET OBESE AND CONTROL INDIVIDUALS. OBESITY IS A HIGHLY PREVALENT, CHRONIC DISORDER THAT HAS BEEN INCREASING IN INCIDENCE IN YOUNG PATIENTS. BOTH EPIGENETIC AND GENETIC ABERRATIONS MAY PLAY A ROLE IN THE PATHOGENESIS OF OBESITY. THEREFORE, IN-DEPTH EPIGENOMIC AND GENOMIC ANALYSES WILL ADVANCE OUR UNDERSTANDING OF THE DETAILED MOLECULAR MECHANISMS UNDERLYING OBESITY AND AID IN THE SELECTION OF POTENTIAL BIOMARKERS FOR OBESITY IN YOUTH. HERE, WE PERFORMED MICROARRAY-BASED DNA METHYLATION AND GENE EXPRESSION PROFILING OF PERIPHERAL WHITE BLOOD CELLS OBTAINED FROM SIX YOUNG, OBESE INDIVIDUALS AND SIX HEALTHY CONTROLS. WE OBSERVED THAT THE HIERARCHICAL CLUSTERING OF DNA METHYLATION, BUT NOT GENE EXPRESSION, CLEARLY SEGREGATES THE OBESE INDIVIDUALS FROM THE CONTROLS, SUGGESTING THAT THE METABOLIC DISTURBANCE THAT OCCURS AS A RESULT OF OBESITY AT A YOUNG AGE MAY AFFECT THE DNA METHYLATION OF PERIPHERAL BLOOD CELLS WITHOUT ACCOMPANYING TRANSCRIPTIONAL CHANGES. TO EXAMINE THE GENOME-WIDE DIFFERENCES IN THE DNA METHYLATION PROFILES OF YOUNG OBESE AND CONTROL INDIVIDUALS, WE IDENTIFIED DIFFERENTIALLY METHYLATED CPG SITES AND INVESTIGATED THEIR GENOMIC AND EPIGENOMIC CONTEXTS. THE ABERRANT DNA METHYLATION PATTERNS IN OBESE INDIVIDUALS CAN BE SUMMARIZED AS RELATIVE GAINS AND LOSSES OF DNA METHYLATION IN GENE PROMOTERS AND GENE BODIES, RESPECTIVELY. WE ALSO OBSERVED THAT THE CPG ISLANDS OF OBESE INDIVIDUALS ARE MORE SUSCEPTIBLE TO DNA METHYLATION COMPARED TO CONTROLS. OUR PILOT STUDY SUGGESTS THAT THE GENOME-WIDE ABERRANT DNA METHYLATION PATTERNS OF OBESE INDIVIDUALS MAY ADVANCE NOT ONLY OUR UNDERSTANDING OF THE EPIGENOMIC PATHOGENESIS BUT ALSO EARLY SCREENING OF OBESITY IN YOUTH. 2017 17 287 27 AGING AND CHRONIC SUN EXPOSURE CAUSE DISTINCT EPIGENETIC CHANGES IN HUMAN SKIN. EPIGENETIC CHANGES ARE WIDELY CONSIDERED TO PLAY AN IMPORTANT ROLE IN AGING, BUT EXPERIMENTAL EVIDENCE TO SUPPORT THIS HYPOTHESIS HAS BEEN SCARCE. WE HAVE USED ARRAY-BASED ANALYSIS TO DETERMINE GENOME-SCALE DNA METHYLATION PATTERNS FROM HUMAN SKIN SAMPLES AND TO INVESTIGATE THE EFFECTS OF AGING, CHRONIC SUN EXPOSURE, AND TISSUE VARIATION. OUR RESULTS REVEAL A HIGH DEGREE OF TISSUE SPECIFICITY IN THE METHYLATION PATTERNS AND ALSO SHOWED VERY LITTLE INTERINDIVIDUAL VARIATION WITHIN TISSUES. DATA STRATIFICATION BY AGE REVEALED THAT DNA FROM OLDER INDIVIDUALS WAS CHARACTERIZED BY A SPECIFIC HYPERMETHYLATION PATTERN AFFECTING LESS THAN 1% OF THE MARKERS ANALYZED. INTERESTINGLY, STRATIFICATION BY SUN EXPOSURE PRODUCED A FUNDAMENTALLY DIFFERENT PATTERN WITH A SIGNIFICANT TREND TOWARDS HYPOMETHYLATION. OUR RESULTS THUS IDENTIFY DEFINED AGE-RELATED DNA METHYLATION CHANGES AND SUGGEST THAT THESE ALTERATIONS MIGHT CONTRIBUTE TO THE PHENOTYPIC CHANGES ASSOCIATED WITH SKIN AGING. 2010 18 2920 30 GENE-SET ANALYSIS IS SEVERELY BIASED WHEN APPLIED TO GENOME-WIDE METHYLATION DATA. MOTIVATION: DNA METHYLATION IS AN EPIGENETIC MARK THAT CAN STABLY REPRESS GENE EXPRESSION. BECAUSE OF ITS BIOLOGICAL AND CLINICAL SIGNIFICANCE, SEVERAL METHODS HAVE BEEN DEVELOPED TO COMPARE GENOME-WIDE PATTERNS OF METHYLATION BETWEEN GROUPS OF SAMPLES. THE APPLICATION OF GENE SET ANALYSIS TO IDENTIFY RELEVANT GROUPS OF GENES THAT ARE ENRICHED FOR DIFFERENTIALLY METHYLATED GENES IS OFTEN A MAJOR COMPONENT OF THE ANALYSIS OF THESE DATA. THIS CAN BE USED, FOR EXAMPLE, TO IDENTIFY PROCESSES OR PATHWAYS THAT ARE PERTURBED IN DISEASE DEVELOPMENT. WE SHOW THAT GENE-SET ANALYSIS, AS IT IS TYPICALLY APPLIED TO GENOME-WIDE METHYLATION ASSAYS, IS SEVERELY BIASED AS A RESULT OF DIFFERENCES IN THE NUMBERS OF CPG SITES ASSOCIATED WITH DIFFERENT CLASSES OF GENES AND GENE PROMOTERS. RESULTS: WE DEMONSTRATE THIS BIAS USING PUBLISHED DATA FROM A STUDY OF DIFFERENTIAL CPG ISLAND METHYLATION IN LUNG CANCER AND A DATASET WE GENERATED TO STUDY METHYLATION CHANGES IN PATIENTS WITH LONG-STANDING ULCERATIVE COLITIS. WE SHOW THAT SEVERAL OF THE GENE SETS THAT SEEM ENRICHED WOULD ALSO BE IDENTIFIED WITH RANDOMIZED DATA. WE SUGGEST TWO EXISTING APPROACHES THAT CAN BE ADAPTED TO CORRECT THE BIAS. ACCOUNTING FOR THE BIAS IN THE LUNG CANCER AND ULCERATIVE COLITIS DATASETS PROVIDES NOVEL BIOLOGICAL INSIGHTS INTO THE ROLE OF METHYLATION IN CANCER DEVELOPMENT AND CHRONIC INFLAMMATION, RESPECTIVELY. OUR RESULTS HAVE SIGNIFICANT IMPLICATIONS FOR MANY PREVIOUS GENOME-WIDE METHYLATION STUDIES THAT HAVE DRAWN CONCLUSIONS ON THE BASIS OF SUCH STRONGLY BIASED ANALYSIS. CONTACT: CATHAL.SEOIGHE@NUIGALWAY.IE SUPPLEMENTARY INFORMATION: SUPPLEMENTARY DATA ARE AVAILABLE AT BIOINFORMATICS ONLINE. 2013 19 2017 33 EPIGENETIC BIOMARKERS IN RHEUMATOLOGY - THE FUTURE? EPIGENETIC CHANGES ARE STABLE MODIFICATIONS OF DNA OR HISTONES THAT PROFOUNDLY ALTER GENE EXPRESSION. THEY CAN BE CHANGED BY ENVIRONMENTAL INFLUENCES AND CAN THEN BE PASSED ON TO DAUGHTER CELLS OR VIA THE GERM LINE TO OFFSPRING. A VARIETY OF CHANGES IN EPIGENETIC MARKS AND IN THE EXPRESSION OF NONCODING RNA HAS BEEN FOUND IN CANCER AS WELL AS IN CHRONIC INFLAMMATORY DISEASES. INTERESTINGLY, IN BOTH DISEASES SIMILAR MECHANISMS AND PATHWAYS ARE AFFECTED ALBEIT OFTEN TO A DIFFERENT EXTENT. DNA METHYLATION IS OFTEN LOST IN REPETITIVE SEQUENCES, WHILE IN PROMOTER REGIONS HYPO- AS WELL AS HYPERMETHYLATION IS FOUND. CHANGES IN MICRORNA LEVELS TYPICALLY AFFECT MICRORNAS THAT ARE CHANGED BY AN INFLAMMATORY ENVIRONMENT, BUT DISEASE SPECIFIC CHANGES HAVE ALSO BEEN FOUND IN THE BLOOD AND VARIOUS CELL TYPES OF PATIENTS WITH RHEUMATOID ARTHRITIS, SYSTEMIC LUPUS ERYTHEMATOSUS AND OTHER RHEUMATIC DISEASES. THEREFORE, CHANGES IN THE EXPRESSION OF MICRORNA IN PARTICULAR, BUT ALSO DEMETHYLATED GENE LOCI, HAVE BEEN PROPOSED AS POTENTIAL BIOMARKERS IN CHRONIC INFLAMMATORY DISEASES AND IN CANCER. POTENTIALLY, THESE CHANGES COULD BE USED FOR EARLY DIAGNOSIS AND ALSO TO PREDICT TREATMENT RESPONSE. UNFORTUNATELY MOST STUDIES IN RHEUMATOLOGY UP TO NOW WERE NOT DESIGNED TO VALIDATE THESE EPIGENETIC CHANGES AS BIOMARKERS. SINCE THE CANCER FIELD IS MUCH MORE ADVANCED IN THE USAGE OF BIOMARKERS FOR DISEASE SUBCLASSIFICATIONS AND SUBSEQUENT THERAPEUTIC DECISIONS, IT IS WORTHWHILE TO TAKE A CLOSER LOOK AT THE BIOMARKERS, METHODS AND PROCEDURES USED IN ONCOLOGY AND TO SEE WHICH OF THESE COULD ALSO BE APPLIED TO PREDICTING DISEASE SEVERITY AND THERAPEUTIC RESPONSE IN RHEUMATIC DISEASES. THIS ARTICLE WILL HIGHLIGHT COMMON EPIGENETIC PATHWAYS ACTIVATED IN CANCER AND VARIOUS RHEUMATIC DISEASES AND SUMMARISE EPIGENETIC CHANGES THAT HAVE THE POTENTIAL TO BECOME BIOMARKERS IN RHEUMATIC DISEASES. 2016 20 2648 25 EPIGENOMIC TARGETS FOR THE TREATMENT OF RESPIRATORY DISEASE. BACKGROUND: A NUMBER OF PROCESSES LEAD TO EPIGENETIC AND EPIGENOMIC MODIFICATIONS. OBJECTIVE: TO ADDRESS THE IMPORTANCE OF EPIGENOMICS IN RESPIRATORY DISEASE. METHODS: STUDIES OF EPIGENOMICS WERE ANALYSED IN RELATION TO CHRONIC RESPIRATORY DISEASES. RESULTS/CONCLUSION: IN LUNG CANCER AND MESOTHELIOMA, A NUMBER OF GENES INVOLVED IN CARCINOGENESIS HAVE BEEN DEMONSTRATED TO BE HYPERMETHYLATED, IMPLICATING EPIGENOMIC CHANGES IN THE AETIOLOGY OF THESE CANCERS. HYPERMETHYLATED GENES HAVE ALSO BEEN ASSOCIATED WITH LUNG CANCER RECURRENCE, INDICATING EPIGENOMIC REGULATION OF METASTASIS. IN AIRWAY DISEASES, MODULATION OF HISTONE FUNCTION MAY ACTIVATE INFLAMMATORY MECHANISMS IN CHRONIC OBSTRUCTIVE PULMONARY DISEASE PATIENTS AND LEAD TO RELATIVE STEROID RESISTANCE. THERE IS EMERGING EVIDENCE FOR THE ROLE OF EPIGENETIC CHANGES IN CHRONIC LUNG DISEASES SUCH AS ASTHMA, INCLUDING RESPONSES TO ENVIRONMENTAL EXPOSURES IN UTERO AND TO THE EFFECTS OF AIR POLLUTION. INSIGHT INTO EPIGENOMICS WILL LEAD TO THE DEVELOPMENT OF NOVEL BIOMARKERS AND TREATMENT TARGETS IN RESPIRATORY DISEASES. 2009