1 1585 110 DNA METHYLATION PROFILING IDENTIFIES EPIGENETIC DIFFERENCES BETWEEN DIABETES PATIENTS WITH ESRD AND DIABETES PATIENTS WITHOUT NEPHROPATHY. WE IDENTIFIED POTENTIAL EPIGENETIC BIOMARKERS FOR CHRONIC KIDNEY DISEASE PROGRESSION BY COMPARING SITE-SPECIFIC DNA METHYLATION LEVELS IN MORE THAN 14,000 GENES BETWEEN AFRICAN AMERICAN AND HISPANIC DIABETES PATIENTS WITH END STAGE RENAL DISEASE (ESRD) AND DIABETES PATIENTS WITHOUT NEPHROPATHY. WE IDENTIFIED 187 GENES THAT ARE DIFFERENTIALLY METHYLATED BETWEEN THE TWO GROUPS ON AT LEAST TWO CPG SITES IN EACH GENE IN DNA EXTRACTED FROM SALIVA. OF THE 187 GENES WHOSE MEAN METHYLATION LEVELS DIFFERED BETWEEN THE TWO GROUPS, 39 GENES, OR CLOSELY RELATED GENE FAMILY MEMBERS, HAVE BEEN REPORTED TO BE INVOLVED IN KIDNEY DEVELOPMENT OR DIABETIC NEPHROPATHY, PER SE, OR HAVE BEEN ASSOCIATED WITH DIALYSIS-INDUCED CHANGES IN GENE EXPRESSION IN PERIPHERAL BLOOD CELLS. THE FACT THAT SUCH A SUBSTANTIAL FRACTION (21%) OF THE 187 CANDIDATE GENES HAVE BEEN IMPLICATED PREVIOUSLY THROUGH GENOME ASSOCIATION OR TRANSCRIPTION PROFILING STUDIES SUGGESTS STRONGLY THAT THE DNA METHYLATION DIFFERENCES WE OBSERVE ARE ASSOCIATED WITH DISEASE PREDISPOSITION AND/OR TREATMENT. THE FACT THAT THESE NEPHROPATHY AND/OR DIALYSIS-ASSOCIATED DIFFERENCES BETWEEN PATIENTS WERE IDENTIFIED IN DNA EXTRACTED FROM SALIVA OFFERS PROOF-OF-PRINCIPLE THAT INTER-INDIVIDUAL EPIGENETIC DIFFERENCES MAY PROVE USEFUL AS PREDICTIVE BIOMARKERS OF DISEASE SUSCEPTIBILITY. 2011 2 1583 41 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 3 287 24 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 4 3 38 "EPIGENOME-WIDE METHYLATION PROFILE OF CHRONIC KIDNEY DISEASE-DERIVED ARTERIAL DNA UNCOVERS NOVEL PATHWAYS IN DISEASE-ASSOCIATED CARDIOVASCULAR PATHOLOGY.". CHRONIC KIDNEY DISEASE (CKD) RELATED CARDIOVASCULAR DISEASE (CVD) IS CHARACTERIZED BY VASCULAR REMODELLING WITH WELL-ESTABLISHED STRUCTURAL AND FUNCTIONAL CHANGES IN THE VASCULAR WALL SUCH AS ARTERIAL STIFFNESS, MATRIX DEPOSITION, AND CALCIFICATION. THESE PHENOTYPIC CHANGES RESEMBLE PATHOLOGY SEEN IN AGEING, AND ARE LIKELY TO BE MEDIATED BY SUSTAINED ALTERATIONS IN GENE EXPRESSION, WHICH MAY BE CAUSED BY EPIGENETIC CHANGES SUCH AS TISSUE-SPECIFIC DNA METHYLATION. WE AIMED TO INVESTIGATE TISSUE SPECIFIC CHANGES IN DNA METHYLATION THAT OCCUR IN CKD-RELATED CVD. GENOME-WIDE DNA METHYLATION CHANGES WERE EXAMINED IN BISULPHITE CONVERTED GENOMIC DNA ISOLATED FROM THE VASCULAR MEDIA OF CKD AND HEALTHY ARTERIES. METHYLATION-SPECIFIC PCR WAS USED TO VALIDATE THE ARRAY DATA, AND THE ASSOCIATION BETWEEN DNA METHYLATION AND GENE AND PROTEIN EXPRESSION WAS EXAMINED. THE DNA METHYLATION AGE WAS COMPARED TO THE CHRONOLOGICAL AGE IN BOTH CASES AND CONTROLS. THREE HUNDRED AND NINETEEN DIFFERENTIALLY METHYLATED REGIONS (DMR) WERE IDENTIFIED SPREAD ACROSS THE GENOME. PATHWAY ANALYSIS REVEALED THAT DMRS ASSOCIATED WITH GENES WERE INVOLVED IN EMBRYONIC AND VASCULAR DEVELOPMENT, AND SIGNALLING PATHWAYS SUCH AS TGFBETA AND FGF. EXPRESSION OF TOP DIFFERENTIALLY METHYLATED GENE HOXA5 SHOWED A SIGNIFICANT NEGATIVE CORRELATION WITH DNA METHYLATION. INTERESTINGLY, DNA METHYLATION AGE AND CHRONOLOGICAL AGE WERE HIGHLY CORRELATED, BUT THERE WAS NO EVIDENCE OF ACCELERATED AGE-RELATED DNA METHYLATION IN THE ARTERIES OF CKD PATIENTS. IN CONCLUSION, WE DEMONSTRATED THAT DIFFERENTIAL DNA METHYLATION IN THE ARTERIAL TISSUE OF CKD PATIENTS REPRESENTS A POTENTIAL MEDIATOR OF ARTERIAL PATHOLOGY AND MAY BE USED TO UNCOVER NOVEL PATHWAYS IN THE GENESIS OF CKD-ASSOCIATED COMPLICATIONS. 2021 5 2920 45 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 6 70 34 A METHOD TO DETECT DIFFERENTIALLY METHYLATED LOCI WITH NEXT-GENERATION SEQUENCING. EPIGENETIC CHANGES, ESPECIALLY DNA METHYLATION AT CPG LOCI HAVE IMPORTANT IMPLICATIONS IN CANCER AND OTHER COMPLEX DISEASES. WITH THE DEVELOPMENT OF NEXT-GENERATION SEQUENCING (NGS), IT IS FEASIBLE TO GENERATE DATA TO INTERROGATE THE DIFFERENCE IN METHYLATION STATUS FOR GENOME-WIDE LOCI USING CASE-CONTROL DESIGN. HOWEVER, A PROPER AND EFFICIENT STATISTICAL TEST IS LACKING. THERE ARE SEVERAL CHALLENGES. FIRST, UNLIKE METHYLATION EXPERIMENTS USING MICROARRAYS, WHERE THERE IS ONE MEASURE OF METHYLATION FOR ONE INDIVIDUAL AT A PARTICULAR CPG SITE, HERE WE HAVE THE COUNTS OF METHYLATION ALLELE AND UNMETHYLATION ALLELE FOR EACH INDIVIDUAL. SECOND, DUE TO THE NATURE OF SAMPLE PREPARATION, THE MEASURED METHYLATION REFLECTS THE METHYLATION STATUS OF A MIXTURE OF CELLS INVOLVED IN SAMPLE PREPARATION. THEREFORE, THE UNDERLYING DISTRIBUTION OF THE MEASURED METHYLATION LEVEL IS UNKNOWN, AND A ROBUST TEST IS MORE DESIRABLE THAN PARAMETRIC APPROACH. THIRD, CURRENTLY NGS MEASURES METHYLATION AT OVER 2 MILLION CPG SITES. ANY STATISTICAL TESTS HAVE TO BE COMPUTATIONALLY EFFICIENT IN ORDER TO BE APPLIED TO THE NGS DATA. TAKING THESE CHALLENGES INTO ACCOUNT, WE PROPOSE A TEST FOR DIFFERENTIAL METHYLATION BASED ON CLUSTERED DATA ANALYSIS BY MODELING THE METHYLATION COUNTS. WE PERFORMED SIMULATIONS TO SHOW THAT IT IS ROBUST UNDER SEVERAL DISTRIBUTIONS FOR THE MEASURED METHYLATION LEVELS. IT HAS GOOD POWER AND IS COMPUTATIONALLY EFFICIENT. FINALLY, WE APPLY THE TEST TO OUR NGS DATA ON CHRONIC LYMPHOCYTIC LEUKEMIA. THE RESULTS INDICATE THAT IT IS A PROMISING AND PRACTICAL TEST. 2013 7 3502 44 IDENTIFICATION OF POTENTIAL BIOMARKERS OF CHRONIC KIDNEY DISEASE IN INDIVIDUALS WITH DIABETES: PROTOCOL FOR A CROSS-SECTIONAL OBSERVATIONAL STUDY. BACKGROUND: THE IMPORTANCE OF IDENTIFYING PEOPLE WITH DIABETES AND PROGRESSIVE KIDNEY DYSFUNCTION RELATES TO THE EXCESS MORBIDITY AND MORTALITY OF THIS GROUP. RATES OF CARDIOVASCULAR DISEASE ARE MUCH HIGHER IN PEOPLE WITH BOTH DIABETES AND KIDNEY DYSFUNCTION THAN IN THOSE WITH ONLY ONE OF THESE CONDITIONS. BY THE TIME THESE PEOPLE ARE IDENTIFIED IN CURRENT CLINICAL PRACTICE, PROTEINURIA AND RENAL DYSFUNCTION ARE ALREADY ESTABLISHED, LIMITING THE EFFECTIVENESS OF THERAPEUTIC INTERVENTIONS. THE IDENTIFICATION OF AN EPIGENETIC OR BLOOD METABOLITE SIGNATURE OR GUT MICROBIOME PROFILE MAY IDENTIFY THOSE WITH DIABETES AT RISK OF PROGRESSIVE CHRONIC KIDNEY DISEASE, IN TURN PROVIDING TARGETED INTERVENTION TO IMPROVE PATIENT OUTCOMES. OBJECTIVE: THIS STUDY AIMS TO IDENTIFY POTENTIAL BIOMARKERS IN PEOPLE WITH DIABETES AND CHRONIC KIDNEY DISEASE (CKD) ASSOCIATED WITH PROGRESSIVE RENAL INJURY AND TO DISTINGUISH BETWEEN STAGES OF CHRONIC KIDNEY DISEASE. THREE SOURCES OF BIOMARKERS WILL BE EXPLORED, INCLUDING DNA METHYLATION PROFILES IN BLOOD LYMPHOCYTES, THE METABOLOMIC PROFILE OF BLOOD-DERIVED PLASMA AND URINE, AND THE GUT MICROBIOME. METHODS: THE CROSS-SECTIONAL STUDY RECRUITED 121 PEOPLE WITH DIABETES AND VARYING STAGES (STAGES 1-5) OF CHRONIC KIDNEY DISEASE. SINGLE-POINT DATA COLLECTION INCLUDED BLOOD, URINE, AND FECAL SAMPLES IN ADDITION TO CLINICAL DATA SUCH AS ANTHROPOMETRIC MEASUREMENTS AND BIOCHEMICAL PARAMETERS. ADDITIONAL INFORMATION OBTAINED FROM MEDICAL RECORDS INCLUDED PATIENT DEMOGRAPHICS, MEDICAL COMORBIDITIES, AND MEDICATIONS. RESULTS: DATA COLLECTION COMMENCED IN JANUARY 2018 AND WAS COMPLETED IN JUNE 2018. AT THE TIME OF SUBMISSION, 121 PATIENTS HAD BEEN RECRUITED, AND 119 SAMPLES REMAINED AFTER QUALITY CONTROL. THERE WERE 83 PARTICIPANTS IN THE EARLY DIABETES-ASSOCIATED CKD GROUP WITH A MEAN ESTIMATED GLOMERULAR FILTRATION RATE (EGFR) OF 61.2 ML/MIN/1.73 M2 (EARLY CKD GROUP CONSISTING OF STAGE 1, 2, AND 3A CKD), AND 36 PARTICIPANTS IN THE LATE DIABETIC CKD GROUP WITH A MEAN EGFR OF 23.9 ML/MIN/1.73 M2 (LATE CKD GROUP, CONSISTING OF STAGE 3B, 4, AND 5), P<.001. WE HAVE SUCCESSFULLY OBTAINED DNA FOR METHYLATION AND MICROBIOME ANALYSES USING THE BIOSPECIMENS COLLECTED VIA THIS PROTOCOL AND ARE CURRENTLY ANALYZING THESE RESULTS TOGETHER WITH THE METABOLOME OF THIS COHORT OF INDIVIDUALS WITH DIABETIC CKD. CONCLUSIONS: RECENT ADVANCES HAVE IMPROVED OUR UNDERSTANDING OF THE EPIGENOME, METABOLOMICS, AND THE INFLUENCE OF THE GUT MICROBIOME ON THE INCIDENCE OF DISEASES SUCH AS CANCERS, PARTICULARLY THOSE RELATED TO ENVIRONMENTAL EXPOSURES. HOWEVER, THERE IS A PAUCITY OF LITERATURE SURROUNDING THESE INFLUENCERS IN RENAL DISEASE. THIS STUDY WILL PROVIDE INSIGHT INTO THE FUNDAMENTAL UNDERSTANDING OF THE PATHOPHYSIOLOGY OF CKD IN INDIVIDUALS WITH DIABETES, ESPECIALLY IN NOVEL AREAS SUCH AS EPIGENETICS, METABOLOMICS, AND THE KIDNEY-GUT AXIS. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/16277. 2020 8 1599 34 DNA METHYLATION SIGNATURE OF CHILDHOOD CHRONIC PHYSICAL AGGRESSION IN T CELLS OF BOTH MEN AND WOMEN. BACKGROUND: HIGH FREQUENCY OF PHYSICAL AGGRESSION IS THE CENTRAL FEATURE OF SEVERE CONDUCT DISORDER AND IS ASSOCIATED WITH A WIDE RANGE OF SOCIAL, MENTAL AND PHYSICAL HEALTH PROBLEMS. WE HAVE PREVIOUSLY TESTED THE HYPOTHESIS THAT DIFFERENTIAL DNA METHYLATION SIGNATURES IN PERIPHERAL T CELLS ARE ASSOCIATED WITH A CHRONIC AGGRESSION TRAJECTORY IN MALES. DESPITE THE FACT THAT SEX DIFFERENCES APPEAR TO PLAY A PIVOTAL ROLE IN DETERMINING THE DEVELOPMENT, MAGNITUDE AND FREQUENCY OF AGGRESSION, MOST OF PREVIOUS STUDIES FOCUSED ON MALES, SO LITTLE IS KNOWN ABOUT FEMALE CHRONIC PHYSICAL AGGRESSION. WE THEREFORE TESTED HERE WHETHER OR NOT THERE IS A SIGNATURE OF PHYSICAL AGGRESSION IN FEMALE DNA METHYLATION AND, IF THERE IS, HOW IT RELATES TO THE SIGNATURE OBSERVED IN MALES. METHODOLOGY/PRINCIPAL FINDINGS: METHYLATION PROFILES WERE CREATED USING THE METHOD OF METHYLATED DNA IMMUNOPRECIPITATION (MEDIP) FOLLOWED BY MICROARRAY HYBRIDIZATION AND STATISTICAL AND BIOINFORMATIC ANALYSES ON T CELL DNA OBTAINED FROM ADULT WOMEN WHO WERE FOUND TO BE ON A CHRONIC PHYSICAL AGGRESSION TRAJECTORY (CPA) BETWEEN 6 AND 12 YEARS OF AGE COMPARED TO WOMEN WHO FOLLOWED A NORMAL PHYSICAL AGGRESSION TRAJECTORY. WE CONFIRMED THE EXISTENCE OF A WELL-DEFINED, GENOME-WIDE SIGNATURE OF DNA METHYLATION ASSOCIATED WITH CHRONIC PHYSICAL AGGRESSION IN THE PERIPHERAL T CELLS OF ADULT FEMALES THAT INCLUDES MANY OF THE GENES SIMILARLY ASSOCIATED WITH PHYSICAL AGGRESSION IN THE SAME CELL TYPES OF ADULT MALES. CONCLUSIONS: THIS STUDY IN A SMALL NUMBER OF WOMEN PRESENTS PRELIMINARY EVIDENCE FOR A GENOME-WIDE VARIATION IN PROMOTER DNA METHYLATION THAT ASSOCIATES WITH CPA IN WOMEN THAT WARRANT LARGER STUDIES FOR FURTHER VERIFICATION. A SIGNIFICANT PROPORTION OF THESE ASSOCIATIONS WERE PREVIOUSLY OBSERVED IN MEN WITH CPA SUPPORTING THE HYPOTHESIS THAT THE EPIGENETIC SIGNATURE OF EARLY LIFE AGGRESSION IN FEMALES IS COMPOSED OF A COMPONENT SPECIFIC TO FEMALES AND ANOTHER COMMON TO BOTH MALES AND FEMALES. 2014 9 2148 36 EPIGENETIC MARKERS OF RENAL FUNCTION IN AFRICAN AMERICANS. CHRONIC KIDNEY DISEASE (CKD) IS AN INCREASING CONCERN IN THE UNITED STATES DUE TO ITS RAPIDLY RISING PREVALENCE, PARTICULARLY AMONG AFRICAN AMERICANS. EPIGENETIC DNA METHYLATION MARKERS ARE BECOMING IMPORTANT BIOMARKERS OF CHRONIC DISEASES SUCH AS CKD. TO BETTER UNDERSTAND HOW THESE METHYLATION MARKERS PLAY A ROLE IN KIDNEY FUNCTION, WE MEASURED 26,428 DNA METHYLATION SITES IN 972 AFRICAN AMERICANS FROM THE GENETIC EPIDEMIOLOGY NETWORK OF ARTERIOPATHY (GENOA) STUDY. WE THEN EVALUATED (1) WHETHER EPIGENETIC MARKERS ARE ASSOCIATED WITH ESTIMATED GLOMERULAR FILTRATION RATE (EGFR), (2) WHETHER THE SIGNIFICANTLY ASSOCIATED MARKERS ARE ALSO ASSOCIATED WITH TRADITIONAL RISK FACTORS AND/OR NOVEL BIOMARKERS FOR EGFR, AND (3) HOW MUCH ADDITIONAL VARIATION IN EGFR IS EXPLAINED BY EPIGENETIC MARKERS BEYOND ESTABLISHED RISK FACTORS AND BIOMARKERS. THE MAJORITY OF METHYLATION MARKERS MOST SIGNIFICANTLY ASSOCIATED WITH EGFR (24 OUT OF THE TOP 30) APPEARED TO FUNCTION, AT LEAST IN PART, THROUGH PATHWAYS RELATED TO AGING, INFLAMMATION, OR CHOLESTEROL. HOWEVER, SIX EPIGENETIC MARKERS WERE STILL ABLE TO SIGNIFICANTLY PREDICT EGFR AFTER ADJUSTMENT FOR OTHER RISK FACTORS. THIS WORK SHOWS THAT EPIGENETIC MARKERS MAY OFFER VALUABLE NEW INSIGHT INTO THE COMPLEX PATHOPHYSIOLOGY OF CKD IN AFRICAN AMERICANS. 2013 10 1503 50 DNA METHYLATION AND GENE EXPRESSION DIFFERENCES IN CHILDREN CONCEIVED IN VITRO OR IN VIVO. EPIDEMIOLOGICAL DATA INDICATE THAT CHILDREN CONCEIVED IN VITRO HAVE A GREATER RELATIVE RISK OF LOW BIRTH-WEIGHT, MAJOR AND MINOR BIRTH DEFECTS, AND RARE DISORDERS INVOLVING IMPRINTED GENES, SUGGESTING THAT EPIGENETIC CHANGES MAY BE ASSOCIATED WITH ASSISTED REPRODUCTION. WE EXAMINED DNA METHYLATION AT MORE THAN 700 GENES (1536 CPG SITES) IN PLACENTA AND CORD BLOOD AND MEASURED GENE EXPRESSION LEVELS OF A SUBSET OF GENES THAT DIFFERED IN METHYLATION LEVELS BETWEEN CHILDREN CONCEIVED IN VITRO VERSUS IN VIVO. OUR RESULTS SUGGEST THAT IN VITRO CONCEPTION IS ASSOCIATED WITH LOWER MEAN METHYLATION AT CPG SITES IN PLACENTA AND HIGHER MEAN METHYLATION AT CPG SITES IN CORD BLOOD. WE ALSO FIND THAT IN VITRO CONCEPTION-ASSOCIATED DNA METHYLATION DIFFERENCES ARE ASSOCIATED WITH GENE EXPRESSION DIFFERENCES AT BOTH IMPRINTED AND NON-IMPRINTED GENES. THE RANGE OF INTER-INDIVIDUAL VARIATION IN GENE EXPRESSION OF THE IN VITRO AND IN VIVO GROUPS OVERLAPS SUBSTANTIALLY BUT SOME INDIVIDUALS FROM THE IN VITRO GROUP DIFFER FROM THE IN VIVO GROUP MEAN BY MORE THAN TWO STANDARD DEVIATIONS. SEVERAL OF THE GENES WHOSE EXPRESSION DIFFERS BETWEEN THE TWO GROUPS HAVE BEEN IMPLICATED IN CHRONIC METABOLIC DISORDERS, SUCH AS OBESITY AND TYPE II DIABETES. THESE FINDINGS SUGGEST THAT THERE MAY BE EPIGENETIC DIFFERENCES IN THE GAMETES OR EARLY EMBRYOS DERIVED FROM COUPLES UNDERGOING TREATMENT FOR INFERTILITY. ALTERNATIVELY, ASSISTED REPRODUCTION TECHNOLOGY MAY HAVE AN EFFECT ON GLOBAL PATTERNS OF DNA METHYLATION AND GENE EXPRESSION. IN EITHER CASE, THESE DIFFERENCES OR CHANGES MAY AFFECT LONG-TERM PATTERNS OF GENE EXPRESSION. 2009 11 1705 44 DYNAMICS OF SMOKING-INDUCED GENOME-WIDE METHYLATION CHANGES WITH TIME SINCE SMOKING CESSATION. SEVERAL STUDIES HAVE RECENTLY IDENTIFIED STRONG EPIGENETIC SIGNALS RELATED TO TOBACCO SMOKING. HOWEVER, AN ASPECT THAT DID NOT RECEIVE MUCH ATTENTION IS THE EVOLUTION OF EPIGENETIC CHANGES WITH TIME SINCE SMOKING CESSATION. WE CONDUCTED A SERIES OF EPIGENOME-WIDE ASSOCIATION STUDIES TO CAPTURE THE DYNAMICS OF SMOKING-INDUCED EPIGENETIC CHANGES AFTER SMOKING CESSATION, USING GENOME-WIDE METHYLATION PROFILES OBTAINED FROM BLOOD SAMPLES IN 745 WOMEN FROM 2 EUROPEAN POPULATIONS. TWO DISTINCT CLASSES OF CPG SITES WERE IDENTIFIED: SITES WHOSE METHYLATION REVERTS TO LEVELS TYPICAL OF NEVER SMOKERS WITHIN DECADES AFTER SMOKING CESSATION, AND SITES REMAINING DIFFERENTIALLY METHYLATED, EVEN MORE THAN 35 YEARS AFTER SMOKING CESSATION. OUR RESULTS SUGGEST THAT THE DYNAMICS OF METHYLATION CHANGES FOLLOWING SMOKING CESSATION ARE DRIVEN BY A DIFFERENTIAL AND SITE-SPECIFIC MAGNITUDE OF THE SMOKING-INDUCED ALTERATIONS (WITH PERSISTENT SITES BEING MOST AFFECTED) IRRESPECTIVE OF THE INTENSITY AND DURATION OF SMOKING. ANALYSES OF THE LINK BETWEEN METHYLATION AND EXPRESSION LEVELS REVEALED THAT METHYLATION PREDOMINANTLY AND REMOTELY DOWN-REGULATES GENE EXPRESSION. AMONG GENES WHOSE EXPRESSION WAS ASSOCIATED WITH OUR CANDIDATE CPG SITES, LRRN3 APPEARED TO BE PARTICULARLY INTERESTING AS IT WAS ONE OF THE FEW GENES WHOSE METHYLATION AND EXPRESSION WERE DIRECTLY ASSOCIATED, AND THE ONLY GENE IN WHICH BOTH METHYLATION AND GENE EXPRESSION WERE FOUND ASSOCIATED WITH SMOKING. OUR STUDY HIGHLIGHTS PERSISTENT EPIGENETIC MARKERS OF SMOKING, WHICH CAN POTENTIALLY BE DETECTED DECADES AFTER CESSATION. SUCH HISTORICAL SIGNATURES ARE PROMISING BIOMARKERS TO REFINE INDIVIDUAL RISK PROFILING OF SMOKING-INDUCED CHRONIC DISEASE SUCH AS LUNG CANCER. 2015 12 1269 39 CYTOSINE METHYLATION CHANGES IN ENHANCER REGIONS OF CORE PRO-FIBROTIC GENES CHARACTERIZE KIDNEY FIBROSIS DEVELOPMENT. BACKGROUND: ONE IN ELEVEN PEOPLE IS AFFECTED BY CHRONIC KIDNEY DISEASE, A CONDITION CHARACTERIZED BY KIDNEY FIBROSIS AND PROGRESSIVE LOSS OF KIDNEY FUNCTION. EPIDEMIOLOGICAL STUDIES INDICATE THAT ADVERSE INTRAUTERINE AND POSTNATAL ENVIRONMENTS HAVE A LONG-LASTING ROLE IN CHRONIC KIDNEY DISEASE DEVELOPMENT. EPIGENETIC INFORMATION REPRESENTS A PLAUSIBLE CARRIER FOR MEDIATING THIS PROGRAMMING EFFECT. HERE WE DEMONSTRATE THAT GENOME-WIDE CYTOSINE METHYLATION PATTERNS OF HEALTHY AND CHRONIC KIDNEY DISEASE TUBULE SAMPLES OBTAINED FROM PATIENTS SHOW SIGNIFICANT DIFFERENCES. RESULTS: WE IDENTIFY DIFFERENTIALLY METHYLATED REGIONS AND VALIDATE THESE IN A LARGE REPLICATION DATASET. THE DIFFERENTIALLY METHYLATED REGIONS ARE RARELY OBSERVED ON PROMOTERS, BUT MOSTLY OVERLAP WITH PUTATIVE ENHANCER REGIONS, AND THEY ARE ENRICHED IN CONSENSUS BINDING SEQUENCES FOR IMPORTANT RENAL TRANSCRIPTION FACTORS. THIS INDICATES THEIR IMPORTANCE IN GENE EXPRESSION REGULATION. A CORE SET OF GENES THAT ARE KNOWN TO BE RELATED TO KIDNEY FIBROSIS, INCLUDING GENES ENCODING COLLAGENS, SHOW CYTOSINE METHYLATION CHANGES CORRELATING WITH DOWNSTREAM TRANSCRIPT LEVELS. CONCLUSIONS: OUR REPORT RAISES THE POSSIBILITY THAT EPIGENETIC DYSREGULATION PLAYS A ROLE IN CHRONIC KIDNEY DISEASE DEVELOPMENT VIA INFLUENCING CORE PRO-FIBROTIC PATHWAYS AND CAN AID THE DEVELOPMENT OF NOVEL BIOMARKERS AND FUTURE THERAPEUTICS. 2013 13 1516 36 DNA METHYLATION AS A BIOMARKER OF AGING IN EPIDEMIOLOGIC STUDIES. CANCER IS LARGELY AN AGING DISEASE. ACCELERATED BIOLOGICAL AGING MAY BE THE STRONGEST PREDICTOR OF CANCER AND OTHER CHRONIC DISEASE RISKS. IN THE ABSENCE OF RELIABLE AND QUANTIFIABLE BIOMARKERS OF AGING TO DATE, IT HAS LONG BEEN OBSERVED THAT TUMORIGENESIS SHARES DISTINCT EPIGENETIC ALTERATIONS WITH THE AGING PROCESS. RECENTLY, EPIGENETIC AGE ESTIMATES HAVE BEEN DEVELOPED BASED ON THE AVAILABILITY OF GENOME-WIDE DNA METHYLATION PROFILES, BY APPLYING IN THE PREDICTION FORMULA THE METHYLATION LEVEL AT A SUBSET OF HIGHLY PREDICTIVE METHYLATION SITES, CALLED EPIGENETIC CLOCK. THESE DNA METHYLATION AGE ESTIMATES HAVE PRODUCED REMARKABLY STRONG CORRELATIONS WITH CHRONOLOGICAL AGE, WITH A SMALL DEVIATION AND HIGH REPRODUCIBILITY ACROSS DIFFERENT AGE GROUPS AND STUDY POPULATIONS. MOREOVER, AN INCREASING NUMBER OF EPIDEMIOLOGIC STUDIES HAVE DEMONSTRATED AN INDEPENDENT ASSOCIATION OF DNA METHYLATION AGE OR THE EXTENT OF ACCELERATION WITH MORTALITY AND VARIOUS AGING-RELATED CONDITIONS, EVEN AFTER ACCOUNTING FOR DIFFERENCES IN CHRONOLOGICAL AGE AND OTHER RISK FACTORS. ALTHOUGH EPIGENETIC PROFILES ARE KNOWN TO BE TISSUE-SPECIFIC, BOTH TARGET TISSUE- AND MULTIPLE TISSUE-DERIVED ESTIMATES APPEAR TO PERFORM WELL TO CAPTURE WHAT IS THOUGHT TO BE THE CUMULATIVE EPIGENETIC DRIFT THAT REPRESENTS A MULTIFACTORIAL DEGENERATIVE PROCESS ACROSS TISSUES AND ORGANISMS. FURTHER REFINEMENT OF THE EPIGENETIC AGE ESTIMATES IS ANTICIPATED OVER TIME TO ACCOMMODATE A BETTER TECHNOLOGICAL COVERAGE OF THE METHYLOME AND A BETTER UNDERSTANDING OF THE BIOLOGY UNDERLYING PREDICTIVE REGIONS. EPIDEMIOLOGIC PRINCIPLES WILL REMAIN CRITICAL FOR THE EVALUATION OF RESEARCH FINDINGS INVOLVING, FOR EXAMPLE, DIFFERENT STUDY POPULATIONS, DESIGN, FOLLOW-UP TIME, AND QUALITY OF COVARIATE DATA. OVERALL, THE EPIGENETIC AGE ESTIMATES ARE AN EXCITING DEVELOPMENT WITH USEFUL IMPLICATIONS FOR BIOMEDICAL RESEARCH OF HEALTHY AGING AND DISEASE PREVENTION AND CONTROL. 2018 14 6311 35 THE RELATION BETWEEN DNA METHYLATION PATTERNS AND SERUM CYTOKINE LEVELS IN COMMUNITY-DWELLING ADULTS: A PRELIMINARY STUDY. BACKGROUND: THE LEVELS OF CIRCULATING CYTOKINES FLUCTUATE WITH AGE, ACUTE ILLNESS, AND CHRONIC DISEASE, AND ARE PREDICTIVE OF MORTALITY; THIS IS ALSO TRUE FOR PATTERNS OF DNA (CPG) METHYLATION. GIVEN THAT IMMUNE CELLS ARE PARTICULARLY SENSITIVE TO CHANGES IN THE CONCENTRATION OF CYTOKINES IN THEIR MICROENVIRONMENT, WE HYPOTHESIZED THAT SERUM LEVELS OF TNF, IL-6, IL-8 AND IL-10 WOULD CORRELATE WITH GENOME-WIDE ALTERATIONS IN THE DNA METHYLATION LEVELS OF BLOOD LEUKOCYTES. TO TEST THIS, WE EVALUATED COMMUNITY-DWELLING ADULTS (N = 14; 48-78 YEARS OLD) RECRUITED TO A PILOT STUDY FOR THE CANADIAN LONGITUDINAL STUDY ON AGING (CLSA), EXAMINING DNA METHYLATION PATTERNS IN PERIPHERAL BLOOD MONONUCLEAR CELLS USING THE ILLUMINA HUMANMETHYLATION 450 K BEADCHIP. RESULTS: WE SHOW THAT, APART FROM AGE, SERUM IL-10 LEVELS EXHIBITED THE MOST SUBSTANTIAL ASSOCIATION TO DNA METHYLATION PATTERNS, FOLLOWED BY TNF, IL-6 AND IL-8. FURTHERMORE, WHILE THE LEVELS OF THESE CYTOKINES WERE HIGHER IN ELDERLY ADULTS, NO ASSOCIATIONS WITH EPIGENETIC ACCELERATED AGING, DERIVED USING THE EPIGENETIC CLOCK, WERE OBSERVED. CONCLUSIONS: AS A PRELIMINARY STUDY WITH A SMALL SAMPLE SIZE, THE CONCLUSIONS DRAWN FROM THIS WORK MUST BE VIEWED WITH CAUTION; HOWEVER, OUR OBSERVATIONS ARE ENCOURAGING AND CERTAINLY WARRANT MORE SUITABLY POWERED STUDIES OF THIS RELATIONSHIP. 2017 15 822 31 CHARACTERIZATION OF BLOOD SURROGATE IMMUNE-METHYLATION BIOMARKERS FOR IMMUNE CELL INFILTRATION IN CHRONIC INFLAMMAGING DISORDERS. ALZHEIMER'S DISEASE (AD) AND ATHEROSCLEROSIS ARE BOTH CHRONIC AGE- AND INFLAMMATION-DEPENDENT DISEASES. IN ADDITION, ATHEROSCLEROSIS IS FREQUENTLY OBSERVED IN AD PATIENTS INDICATING COMMON INVOLVEMENT OF VASCULAR COMPONENTS IN BOTH DISEASE ETIOLOGIES. RECENTLY, EPIGENOME-WIDE ASSOCIATION STUDIES HAVE IDENTIFIED EPIGENETIC ALTERATIONS, AND IN PARTICULARLY DNA METHYLATION CHANGES FOR BOTH DISORDERS. WE HYPOTHESIZED THE EXISTENCE OF A COMMON DNA METHYLATION PROFILE IN ATHEROSCLEROSIS AND AD WHICH MAY BE VALUABLE AS A BLOOD-BASED DNA METHYLATION INFLAMMAGING BIOMARKER. USING PUBLICLY AVAILABLE 450K ILLUMINA METHYLATION DATASETS, WE IDENTIFIED A CO-METHYLATION NETWORK ASSOCIATED WITH BOTH ATHEROSCLEROSIS AND AD IN WHOLE BLOOD SAMPLES. THIS METHYLATION PROFILE APPEARED TO INDICATE SHIFTS IN BLOOD IMMUNE CELL TYPE DISTRIBUTION. REMARKABLY, SIMILAR METHYLATION CHANGES WERE ALSO DETECTED IN DISEASE TISSUES, INCLUDING AD BRAIN TISSUES, ATHEROSCLEROTIC PLAQUES, AND TUMORS AND WERE FOUND TO CORRELATE WITH IMMUNE CELL INFILTRATION. IN ADDITION, THIS IMMUNE-RELATED METHYLATION PROFILE COULD ALSO BE DETECTED IN OTHER INFLAMMAGING DISEASES, INCLUDING PARKINSON'S DISEASE AND OBESITY, BUT NOT IN MULTIPLE SCLEROSIS, SCHIZOPHRENIA, AND OSTEOPOROSIS. IN CONCLUSION, WE IDENTIFIED A BLOOD-BASED IMMUNE-RELATED DNA METHYLATION SIGNATURE IN MULTIPLE INFLAMMAGING DISEASES ASSOCIATED WITH CHANGES IN BLOOD IMMUNE CELL COUNTS AND PREDICTIVE FOR IMMUNE CELL INFILTRATION IN DISEASED TISSUES. IN ADDITION TO EPIGENETIC CLOCK MEASUREMENTS, THIS IMMUNE-METHYLATION SIGNATURE MAY BECOME A VALUABLE BLOOD-BASED BIOMARKER TO PREVENT CHRONIC INFLAMMATORY DISEASE DEVELOPMENT OR MONITOR LIFESTYLE INTERVENTION STRATEGIES WHICH PROMOTE HEALTHY AGING. 2019 16 5741 36 SMOKING INDUCES DNA METHYLATION CHANGES IN MULTIPLE SCLEROSIS PATIENTS WITH EXPOSURE-RESPONSE RELATIONSHIP. CIGARETTE SMOKING IS AN ESTABLISHED ENVIRONMENTAL RISK FACTOR FOR MULTIPLE SCLEROSIS (MS), A CHRONIC INFLAMMATORY AND NEURODEGENERATIVE DISEASE, ALTHOUGH A MECHANISTIC BASIS REMAINS LARGELY UNKNOWN. WE AIMED AT INVESTIGATING HOW SMOKING AFFECTS BLOOD DNA METHYLATION IN MS PATIENTS, BY ASSAYING GENOME-WIDE DNA METHYLATION AND COMPARING SMOKERS, FORMER SMOKERS AND NEVER SMOKERS IN TWO SWEDISH COHORTS, DIFFERING FOR KNOWN MS RISK FACTORS. SMOKING AFFECTS DNA METHYLATION GENOME-WIDE SIGNIFICANTLY, AN EXPOSURE-RESPONSE RELATIONSHIP EXISTS AND THE TIME SINCE SMOKING CESSATION AFFECTS METHYLATION LEVELS. THE RESULTS ALSO SHOW THAT THE CHANGES WERE LARGER IN THE COHORT BEARING THE MAJOR GENETIC RISK FACTORS FOR MS (FEMALE SEX AND HLA RISK HAPLOTYPES). FURTHERMORE, CPG SITES MAPPING TO GENES WITH KNOWN GENETIC OR FUNCTIONAL ROLE IN THE DISEASE ARE DIFFERENTIALLY METHYLATED BY SMOKING. MODELING OF THE METHYLATION LEVELS FOR A CPG SITE IN THE AHRR GENE INDICATES THAT MS MODIFIES THE EFFECT OF SMOKING ON METHYLATION CHANGES, BY SIGNIFICANTLY INTERACTING WITH THE EFFECT OF SMOKING LOAD. ALONGSIDE, WE REPORT THAT THE GENE EXPRESSION OF AHRR INCREASED IN MS PATIENTS AFTER SMOKING. OUR RESULTS SUGGEST THAT EPIGENETIC MODIFICATIONS MAY REVEAL THE LINK BETWEEN A MODIFIABLE RISK FACTOR AND THE PATHOGENETIC MECHANISMS. 2017 17 1345 44 DETECTION OF DIFFERENTIALLY METHYLATED REGIONS USING BAYES FACTOR FOR ORDINAL GROUP RESPONSES. RESEARCHERS IN GENOMICS ARE INCREASINGLY INTERESTED IN EPIGENETIC FACTORS SUCH AS DNA METHYLATION, BECAUSE THEY PLAY AN IMPORTANT ROLE IN REGULATING GENE EXPRESSION WITHOUT CHANGES IN THE DNA SEQUENCE. THERE HAVE BEEN SIGNIFICANT ADVANCES IN DEVELOPING STATISTICAL METHODS TO DETECT DIFFERENTIALLY METHYLATED REGIONS (DMRS) ASSOCIATED WITH BINARY DISEASE STATUS. MOST OF THESE METHODS ARE BEING DEVELOPED FOR DETECTING DIFFERENTIAL METHYLATION RATES BETWEEN CASES AND CONTROLS. WE CONSIDER MULTIPLE SEVERITY LEVELS OF DISEASE, AND DEVELOP A BAYESIAN STATISTICAL METHOD TO DETECT THE REGION WITH INCREASING (OR DECREASING) METHYLATION RATES AS THE DISEASE SEVERITY INCREASES. PATIENTS ARE CLASSIFIED INTO MORE THAN TWO GROUPS, BASED ON THE DISEASE SEVERITY (E.G., STAGES OF CANCER), AND DMRS ARE DETECTED BY USING MOVING WINDOWS ALONG THE GENOME. WITHIN EACH WINDOW, THE BAYES FACTOR IS CALCULATED TO TEST THE HYPOTHESIS OF MONOTONIC INCREASE IN METHYLATION RATES CORRESPONDING TO SEVERITY OF THE DISEASE VERSUS NO DIFFERENCE. A MIXED-EFFECT MODEL IS USED TO INCORPORATE THE CORRELATION OF METHYLATION RATES OF NEARBY CPG SITES IN THE REGION. RESULTS FROM EXTENSIVE SIMULATION INDICATE THAT OUR PROPOSED METHOD IS STATISTICALLY VALID AND REASONABLY POWERFUL. WE DEMONSTRATE OUR APPROACH ON A BISULFITE SEQUENCING DATASET FROM A CHRONIC LYMPHOCYTIC LEUKEMIA (CLL) STUDY. 2019 18 3652 33 INDIVIDUAL DNA METHYLATION PATTERN SHIFTS IN NANOPARTICLES-EXPOSED WORKERS ANALYZED IN FOUR CONSECUTIVE YEARS. A DNA METHYLATION PATTERN REPRESENTS AN ORIGINAL PLAN OF THE FUNCTION SETTINGS OF INDIVIDUAL CELLS AND TISSUES. THE BASIC STRATEGIES OF ITS DEVELOPMENT AND CHANGES DURING THE HUMAN LIFETIME ARE KNOWN, BUT THE DETAILS RELATED TO ITS MODIFICATION OVER THE YEARS ON AN INDIVIDUAL BASIS HAVE NOT YET BEEN STUDIED. MOREOVER, CURRENT EVIDENCE SHOWS THAT ENVIRONMENTAL EXPOSURE COULD GENERATE CHANGES IN DNA METHYLATION SETTINGS AND, SUBSEQUENTLY, THE FUNCTION OF GENES. IN THIS STUDY, WE ANALYZED THE EFFECT OF CHRONIC EXPOSURE TO NANOPARTICLES (NP) IN OCCUPATIONALLY EXPOSED WORKERS REPEATEDLY SAMPLED IN FOUR CONSECUTIVE YEARS (2016-2019). A DETAILED METHYLATION PATTERN ANALYSIS OF 14 PERSONS (10 EXPOSED AND 4 CONTROLS) WAS PERFORMED ON AN INDIVIDUAL BASIS. A MICROARRAY-BASED APPROACH USING CHIPS, ALLOWING THE ASSESSMENT OF MORE THAN 850 K CPG LOCI, WAS USED. INDIVIDUAL DNA METHYLATION PATTERNS WERE COMPARED BY PRINCIPAL COMPONENT ANALYSIS (PCA). THE RESULTS SHOW THE SHIFT IN DNA METHYLATION PATTERNS IN INDIVIDUAL YEARS IN ALL THE EXPOSED AND CONTROL SUBJECTS. THE OVERALL RANGE OF DIFFERENCES VARIED BETWEEN THE YEARS IN INDIVIDUAL PERSONS. THE DIFFERENCES BETWEEN THE FIRST AND LAST YEAR OF EXAMINATION (A THREE-YEAR TIME PERIOD) SEEM TO BE CONSISTENTLY GREATER IN THE NP-EXPOSED SUBJECTS IN COMPARISON WITH THE CONTROLS. THE SELECTED 14 MOST DIFFERENTLY METHYLATED CG LOCI WERE RELATIVELY STABLE IN THE CHRONICALLY EXPOSED SUBJECTS. IN SUMMARY, THE SPECIFIC TYPE OF LONG-TERM EXPOSURE CAN CONTRIBUTE TO THE FIXING OF RELEVANT EPIGENETIC CHANGES RELATED TO A SPECIFIC ENVIRONMENT AS, E.G., NP INHALATION. 2021 19 3994 38 LONGITUDINAL PROFILING IN PATIENTS UNDERGOING CARDIAC SURGERY REVEALS POSTOPERATIVE CHANGES IN DNA METHYLATION. BACKGROUND: CARDIAC SURGERY AND CARDIOPULMONARY BYPASS INDUCE A SUBSTANTIAL IMMUNE AND INFLAMMATORY RESPONSE, THE OVERACTIVATION OF WHICH IS ASSOCIATED WITH SIGNIFICANT PULMONARY, CARDIOVASCULAR, AND NEUROLOGIC COMPLICATIONS. COMMENSURATE WITH THE IMMUNE AND INFLAMMATORY RESPONSE ARE CHANGES IN THE HEART AND VASCULATURE ITSELF, WHICH TOGETHER DRIVE POSTOPERATIVE COMPLICATIONS THROUGH MECHANISMS THAT ARE POORLY UNDERSTOOD. LONGITUDINAL DNA METHYLATION PROFILING HAS THE POTENTIAL TO IDENTIFY CHANGES IN GENE REGULATORY MECHANISMS THAT ARE SECONDARY TO SURGERY AND TO IDENTIFY MOLECULAR PROCESSES THAT PREDICT AND/OR CAUSE POSTOPERATIVE COMPLICATIONS. IN THIS STUDY, WE MEASURE DNA METHYLATION IN PREOPERATIVE AND POSTOPERATIVE WHOLE BLOOD SAMPLES FROM 96 PATIENTS UNDERGOING CARDIAC SURGERY ON CARDIOPULMONARY BYPASS. RESULTS: WHILE THE VAST MAJORITY OF DNA METHYLATION IS UNCHANGED BY SURGERY AFTER ACCOUNTING FOR CHANGES IN CELL-TYPE COMPOSITION, WE IDENTIFY SEVERAL LOCI WITH STATISTICALLY SIGNIFICANT POSTOPERATIVE CHANGES IN METHYLATION. ADDITIONALLY, TWO OF THESE LOCI ARE ASSOCIATED WITH NEW-ONSET POSTOPERATIVE ATRIAL FIBRILLATION, A SIGNIFICANT COMPLICATION AFTER CARDIAC SURGERY. PAIRED STATISTICAL ANALYSIS, USE OF FACS DATA TO SUPPORT SUFFICIENT CONTROL OF CELL-TYPE HETEROGENEITY, AND MEASUREMENT OF IL6 LEVELS IN A SUBSET OF PATIENTS ADD RIGOR TO THIS ANALYSIS, ALLOWING US TO DISTINGUISH CELL-TYPE VARIABILITY FROM ACTUAL CHANGES IN METHYLATION. CONCLUSIONS: THIS STUDY IDENTIFIES SIGNIFICANT CHANGES IN DNA METHYLATION THAT OCCUR IMMEDIATELY AFTER CARDIAC SURGERY AND DEMONSTRATES THAT THESE ACUTE ALTERATIONS IN DNA METHYLATION HAVE THE GRANULARITY TO IDENTIFY PROCESSES ASSOCIATED WITH MAJOR POSTOPERATIVE COMPLICATIONS. THIS RESEARCH ALSO ESTABLISHES METHODS FOR CONTROLLING FOR CELL-TYPE VARIABILITY IN A LARGE HUMAN COHORT THAT MAY BE USEFUL TO DEPLOY IN OTHER LONGITUDINAL STUDIES OF EPIGENETIC MARKS IN THE SETTING OF ACUTE AND CHRONIC DISEASE. 2022 20 274 28 AGE-RELATED CHANGES IN DNA METHYLATION AFFECT RENAL HISTOLOGY AND POST-TRANSPLANT FIBROSIS. DURING AGEING, KIDNEY FUNCTION DECREASES DUE TO RENAL TUBULAR ATROPHY, INTERSTITIAL FIBROSIS, GLOMERULOSCLEROSIS AND ARTERIOSCLEROSIS. RECENTLY, CHANGES IN DNA METHYLATION WERE SHOWN TO CONTRIBUTE TO VARIOUS AGEING PROCESSES. HOWEVER, IT IS UNKNOWN WHETHER SUCH CHANGES ALSO CONTRIBUTE TO AGE-RELATED KIDNEY DYSFUNCTION. TO ASSESS THIS, WE PROFILED GENOME-WIDE CHANGES IN DNA METHYLATION (OVER 800 000 CPG SITES) IN 95 RENAL BIOPSIES OBTAINED PRIOR TO KIDNEY TRANSPLANTATION FROM DONORS AGED 16 TO 73 YEARS. DONOR AGE SIGNIFICANTLY ASSOCIATED WITH THE METHYLATION OF 92 778 CPGS (FALSE DISCOVERY RATE UNDER 0.05), CORRESPONDING TO 10 285 DIFFERENTIALLY METHYLATED REGIONS. THESE REGIONS WERE MOST FREQUENTLY LOCATED IN GENES INVOLVED IN THE WNT/BETA-CATENIN SIGNALING PATHWAY. USING AN INDEPENDENT COHORT OF 67 BIOPSIES, WE AUTONOMOUSLY VALIDATED THESE FINDINGS. INTERESTINGLY, THE METHYLATION STATUS OF THESE 92 778 AGE-RELATED CPGS WAS ASSOCIATED WITH GLOMERULOSCLEROSIS (34.4% OF CPGS AT A FALSE DISCOVERY RATE UNDER 0.05) AND INTERSTITIAL FIBROSIS (0.9%) AND GRAFT FUNCTION AT ONE YEAR AFTER TRANSPLANTATION, BUT NOT WITH TUBULAR ATROPHY AND ARTERIOSCLEROSIS. NO ASSOCIATION WAS OBSERVED WITH ANY OF THESE PATHOLOGIES AT THE TIME OF TRANSPLANTATION (0% AT A FALSE DISCOVERY RATE UNDER 0.05). THUS, AGE-ASSOCIATED CHANGES IN DNA METHYLATION AT THE TIME OF TRANSPLANTATION PREDICT FUTURE INJURY OF TRANSPLANTED KIDNEYS. SPECIFICALLY, OUR EPIGENOME-WIDE ASSOCIATION STUDY DEMONSTRATES THAT EPIGENETIC RENAL AGEING IS IMPLICATED IN PROGRESSIVE FIBROSIS IN BOTH THE GLOMERULUS AND THE INTERSTITIUM. 2019