1 351 149 ALTERED ENDOTHELIAL DYSFUNCTION-RELATED MIRS IN PLASMA FROM ME/CFS PATIENTS. MYALGIC ENCEPHALOMYELITIS/CHRONIC FATIGUE SYNDROME (ME/CFS) IS A COMPLEX DISEASE CHARACTERIZED BY UNEXPLAINED DEBILITATING FATIGUE. ALTHOUGH THE ETIOLOGY IS UNKNOWN, EVIDENCE SUPPORTS IMMUNOLOGICAL ABNORMALITIES, SUCH AS PERSISTENT INFLAMMATION AND IMMUNE-CELL ACTIVATION, IN A SUBSET OF PATIENTS. SINCE THE INTERPLAY BETWEEN INFLAMMATION AND VASCULAR ALTERATIONS IS WELL-ESTABLISHED IN OTHER DISEASES, ENDOTHELIAL DYSFUNCTION HAS EMERGED AS ANOTHER PLAYER IN ME/CFS PATHOGENESIS. ENDOTHELIAL NITRIC OXIDE SYNTHASE (ENOS) GENERATES NITRIC OXIDE (NO) THAT MAINTAINS ENDOTHELIAL HOMEOSTASIS. ENOS IS ACTIVATED BY SILENT INFORMATION REGULATOR 1 (SIRT1), AN ANTI-INFLAMMATORY PROTEIN. DESPITE ITS RELEVANCE, NO STUDY HAS ADDRESSED THE SIRT1/ENOS AXIS IN ME/CFS. THE INTEREST IN CIRCULATING MICRORNAS (MIRS) AS POTENTIAL BIOMARKERS IN ME/CFS HAS INCREASED IN RECENT YEARS. ACCORDINGLY, WE ANALYZE A SET OF MIRS REPORTED TO MODULATE THE SIRT1/ENOS AXIS USING PLASMA FROM ME/CFS PATIENTS. OUR RESULTS SHOW THAT MIR-21, MIR-34A, MIR-92A, MIR-126, AND MIR-200C ARE JOINTLY INCREASED IN ME/CFS PATIENTS COMPARED TO HEALTHY CONTROLS. A SIMILAR FINDING WAS OBTAINED WHEN ANALYZING PUBLIC MIR DATA ON PERIPHERAL BLOOD MONONUCLEAR CELLS. BIOINFORMATICS ANALYSIS SHOWS THAT ENDOTHELIAL FUNCTION-RELATED SIGNALING PATHWAYS ARE ASSOCIATED WITH THESE MIRS, INCLUDING OXIDATIVE STRESS AND OXYGEN REGULATION. INTERESTINGLY, HISTONE DEACETYLASE 1, A PROTEIN RESPONSIBLE FOR EPIGENETIC REGULATIONS, REPRESENTED THE MOST RELEVANT NODE WITHIN THE NETWORK. IN CONCLUSION, OUR STUDY PROVIDES A BASIS TO FIND ENDOTHELIAL DYSFUNCTION-RELATED BIOMARKERS AND EXPLORE NOVEL TARGETS IN ME/CFS. 2021 2 1132 31 COMPREHENSIVE DNA METHYLATION ANALYSIS USING A METHYL-CPG-BINDING DOMAIN CAPTURE-BASED METHOD IN CHRONIC LYMPHOCYTIC LEUKEMIA PATIENTS. THE ROLE OF LONG NONCODING RNAS (LNCRNAS) IN CANCER IS COMING TO THE FOREFRONT DUE TO GROWING INTEREST IN UNDERSTANDING THEIR MECHANISTIC FUNCTIONS DURING CANCER DEVELOPMENT AND PROGRESSION. DESPITE THIS, THE GLOBAL EPIGENETIC REGULATION OF LNCRNAS AND REPETITIVE SEQUENCES IN CANCER HAS NOT BEEN WELL INVESTIGATED, PARTICULARLY IN CHRONIC LYMPHOCYTIC LEUKEMIA (CLL). THIS STUDY FOCUSES ON A UNIQUE APPROACH: THE IMMUNOPRECIPITATION-BASED CAPTURE OF DOUBLE-STRANDED, METHYLATED DNA FRAGMENTS USING METHYL-BINDING DOMAIN (MBD) PROTEINS, FOLLOWED BY NEXT-GENERATION SEQUENCING (MBD-SEQ). CLL PATIENT SAMPLES BELONGING TO TWO PROGNOSTIC SUBGROUPS (5 IGVH MUTATED SAMPLES + 5 IGVH UNMUTATED SAMPLES) WERE USED IN THIS STUDY. ANALYSIS REVEALED 5,800 HYPERMETHYLATED AND 12,570 HYPOMETHYLATED CLL-SPECIFIC DIFFERENTIALLY METHYLATED GENES (CLLDMGS) COMPARED TO NORMAL HEALTHY CONTROLS. IMPORTANTLY, THESE RESULTS IDENTIFIED SEVERAL CLL-SPECIFIC, DIFFERENTIALLY METHYLATED LNCRNAS, REPETITIVE ELEMENTS, AND PROTEIN-CODING GENES WITH POTENTIAL PROGNOSTIC VALUE. THIS WORK OUTLINES A DETAILED PROTOCOL FOR AN MBD-SEQ AND BIOINFORMATICS PIPELINE DEVELOPED FOR THE COMPREHENSIVE ANALYSIS OF GLOBAL METHYLATION PROFILES IN HIGHLY CPG-RICH REGIONS USING CLL PATIENT SAMPLES. FINALLY, A PROTEIN-CODING GENE AND AN LNCRNA WERE VALIDATED USING PYROSEQUENCING, WHICH IS A HIGHLY QUANTITATIVE METHOD TO ANALYZE CPG METHYLATION LEVELS TO FURTHER CORROBORATE THE FINDINGS FROM THE MBD-SEQ PROTOCOL. 2017 3 2765 34 EXPRESSION, EPIGENETIC REGULATION, AND HUMORAL IMMUNOGENICITY OF CANCER-TESTIS ANTIGENS IN CHRONIC MYELOID LEUKEMIA. OBJECTIVE: CANCER-TESTIS (CT) ANTIGENS REPRESENT ATTRACTIVE TARGETS FOR TUMOR IMMUNOTHERAPY BASED ON THEIR TUMOR-RESTRICTED EXPRESSION AND IMMUNOGENICITY. HOWEVER, A BROAD PICTURE OF THE EXPRESSION OF CT ANTIGENS AND ASSOCIATED HUMORAL IMMUNE RESPONSES IN CHRONIC MYELOID LEUKEMIA (CML) IS STILL MISSING. METHODS: WE SCREENED CML CELL LINES AND BONE MARROW (BM) SAMPLES FROM HEALTHY DONORS BY RT-PCR FOR THE EXPRESSION OF 31 CT ANTIGENS BEFORE AND AFTER TREATMENT WITH EPIGENETIC AGENTS. EXPRESSION OF TUMOR-RESTRICTED ANTIGENS WAS FURTHER EXAMINED IN 60 CML PATIENTS AND HUMORAL IMMUNE RESPONSES AGAINST 15 CT ANTIGENS WERE SCREENED BY ELISA. RESULTS: IN UNTREATED CELL LINES WE DETECTED THE EXPRESSION OF 17 CT ANTIGENS THAT WERE ABSENT FROM NORMAL BM. EXPRESSION OF MOST ANTIGENS INCREASED FOLLOWING DEMETHYLATING TREATMENT WITH 5'-AZA-2'-DEOXYCYTIDINE. IN THESE SAMPLES, ONLY PRAME WAS REPEATEDLY DETECTED AND EXPRESSION CORRELATED WITH SEVERAL CLINICOPATHOLOGICAL PARAMETERS AND DECREASED OVERALL SURVIVAL. WE FURTHER SHOW THAT A LOWER FREQUENCY OF PRAME-POSITIVE SAMPLES DURING IMATINIB TREATMENT WAS NOT CAUSED BY GENE-SPECIFIC DOWNREGULATION. ANALYZING THE PATIENTS' ANTIBODY RESPONSES WE FOUND THAT THE VAST MAJORITY OF PATIENTS LACKED SPONTANEOUS IMMUNITY AGAINST CT ANTIGENS INCLUDING PRAME. CONCLUSIONS: CT ANTIGEN EXPRESSION CAN BE INCREASED BY THE APPLICATION OF EPIGENETIC AGENTS AND THE EXPRESSION OF PRAME CORRELATES WITH CLINICOPATHOLOGICAL PARAMETERS AND OVERALL SURVIVAL IN PATIENTS WITH CML, BUT DOES NOT LEAD TO HUMORAL IMMUNE RESPONSES. PRAME-SPECIFIC IMMUNOTHERAPY MIGHT REPRESENT A PROMISING APPROACH FOR THE ERADICATION OF RESIDUAL THERAPY-RESISTANT LEUKEMIC CELLS DUE TO ITS FREQUENT EXPRESSION AND STABILITY UNDER IMATINIB TREATMENT. 2010 4 812 49 CHANGES IN DNA METHYLATION PROFILES OF MYALGIC ENCEPHALOMYELITIS/CHRONIC FATIGUE SYNDROME PATIENTS REFLECT SYSTEMIC DYSFUNCTIONS. BACKGROUND: MYALGIC ENCEPHALOMYELITIS/CHRONIC FATIGUE SYNDROME (ME/CFS) IS A LIFELONG DEBILITATING DISEASE WITH A COMPLEX PATHOLOGY NOT YET CLEARLY DEFINED. SUSCEPTIBILITY TO ME/CFS INVOLVES GENETIC PREDISPOSITION AND EXPOSURE TO ENVIRONMENTAL FACTORS, SUGGESTING AN EPIGENETIC ASSOCIATION. EPIGENETIC STUDIES WITH OTHER ME/CFS COHORTS HAVE USED ARRAY-BASED TECHNOLOGY TO IDENTIFY DIFFERENTIALLY METHYLATED INDIVIDUAL SITES. CHANGES IN RNA QUANTITIES AND PROTEIN ABUNDANCE HAVE BEEN DOCUMENTED IN OUR PREVIOUS INVESTIGATIONS WITH THE SAME ME/CFS COHORT USED FOR THIS STUDY. RESULTS: DNA FROM A WELL-CHARACTERISED NEW ZEALAND COHORT OF 10 ME/CFS PATIENTS AND 10 AGE-/SEX-MATCHED HEALTHY CONTROLS WAS ISOLATED FROM PERIPHERAL BLOOD MONONUCLEAR (PBMC) CELLS, AND USED TO GENERATE REDUCED GENOME-SCALE DNA METHYLATION MAPS USING REDUCED REPRESENTATION BISULPHITE SEQUENCING (RRBS). THE SEQUENCING DATA WERE ANALYSED UTILISING THE DMAP ANALYSIS PIPELINE TO IDENTIFY DIFFERENTIALLY METHYLATED FRAGMENTS, AND THE METHYLKIT PIPELINE WAS USED TO QUANTIFY METHYLATION DIFFERENCES AT INDIVIDUAL CPG SITES. DMAP IDENTIFIED 76 DIFFERENTIALLY METHYLATED FRAGMENTS AND METHYLKIT IDENTIFIED 394 DIFFERENTIALLY METHYLATED CYTOSINES THAT INCLUDED BOTH HYPER- AND HYPO-METHYLATION. FOUR CLUSTERS WERE IDENTIFIED WHERE DIFFERENTIALLY METHYLATED DNA FRAGMENTS OVERLAPPED WITH OR WERE WITHIN CLOSE PROXIMITY TO MULTIPLE DIFFERENTIALLY METHYLATED INDIVIDUAL CYTOSINES. THESE CLUSTERS IDENTIFIED REGULATORY REGIONS FOR 17 PROTEIN ENCODING GENES RELATED TO METABOLIC AND IMMUNE ACTIVITY. ANALYSIS OF DIFFERENTIALLY METHYLATED GENE BODIES (EXONS/INTRONS) IDENTIFIED 122 UNIQUE GENES. COMPARISON WITH OTHER STUDIES ON PBMCS FROM ME/CFS PATIENTS AND CONTROLS WITH ARRAY TECHNOLOGY SHOWED 59% OF THE GENES IDENTIFIED IN THIS STUDY WERE ALSO FOUND IN ONE OR MORE OF THESE STUDIES. FUNCTIONAL PATHWAY ENRICHMENT ANALYSIS IDENTIFIED 30 ASSOCIATED PATHWAYS. THESE INCLUDED IMMUNE, METABOLIC AND NEUROLOGICAL-RELATED FUNCTIONS DIFFERENTIALLY REGULATED IN ME/CFS PATIENTS COMPARED TO THE MATCHED HEALTHY CONTROLS. CONCLUSIONS: MAJOR DIFFERENCES WERE IDENTIFIED IN THE DNA METHYLATION PATTERNS OF ME/CFS PATIENTS THAT CLEARLY DISTINGUISHED THEM FROM THE HEALTHY CONTROLS. OVER HALF FOUND IN GENE BODIES WITH RRBS IN THIS STUDY HAD BEEN IDENTIFIED IN OTHER ME/CFS STUDIES USING THE SAME CELLS BUT WITH ARRAY TECHNOLOGY. WITHIN THE ENRICHED FUNCTIONAL IMMUNE, METABOLIC AND NEUROLOGICAL PATHWAYS, A NUMBER OF ENRICHED NEUROTRANSMITTER AND NEUROPEPTIDE REACTOME PATHWAYS HIGHLIGHTED A DISTURBED NEUROLOGICAL PATHOPHYSIOLOGY WITHIN THE PATIENT GROUP. 2020 5 5706 37 SINGLE-MOLECULE QUANTIFICATION OF 5-HYDROXYMETHYLCYTOSINE FOR DIAGNOSIS OF BLOOD AND COLON CANCERS. BACKGROUND: THE DNA MODIFICATION 5-HYDROXYMETHYLCYTOSINE (5HMC) IS NOW REFERRED TO AS THE SIXTH BASE OF DNA WITH EVIDENCE OF TISSUE-SPECIFIC PATTERNS AND CORRELATION WITH GENE REGULATION AND EXPRESSION. THIS EPIGENETIC MARK WAS RECENTLY REPORTED AS A POTENTIAL BIOMARKER FOR MULTIPLE TYPES OF CANCER, BUT ITS APPLICATION IN THE CLINIC IS LIMITED BY THE UTILITY OF RECENT 5HMC QUANTIFICATION ASSAYS. WE USE A RECENTLY DEVELOPED, ULTRA-SENSITIVE, FLUORESCENCE-BASED SINGLE-MOLECULE METHOD FOR GLOBAL QUANTIFICATION OF 5HMC IN GENOMIC DNA. THE HIGH SENSITIVITY OF THE METHOD GIVES ACCESS TO PRECISE QUANTIFICATION OF EXTREMELY LOW 5HMC LEVELS COMMON IN MANY CANCERS. METHODS: WE ASSESSED 5HMC LEVELS IN DNA EXTRACTED FROM A SET OF COLON AND BLOOD CANCER SAMPLES AND COMPARED 5HMC LEVELS WITH HEALTHY CONTROLS, IN A SINGLE-MOLECULE APPROACH. RESULTS: USING OUR METHOD, WE OBSERVED A SIGNIFICANTLY REDUCED LEVEL OF 5HMC IN BLOOD AND COLON CANCERS AND COULD DISTINGUISH BETWEEN COLON TUMOR AND COLON TISSUE ADJACENT TO THE TUMOR BASED ON THE GLOBAL LEVELS OF THIS MOLECULAR BIOMARKER. CONCLUSIONS: SINGLE-MOLECULE DETECTION OF 5HMC ALLOWS DISTINGUISHING BETWEEN MALIGNANT AND HEALTHY TISSUE IN CLINICALLY RELEVANT AND ACCESSIBLE TISSUE SUCH AS BLOOD AND COLON. THE PRESENTED METHOD OUTPERFORMS CURRENT COMMERCIALLY AVAILABLE QUANTIFICATION KITS AND MAY POTENTIALLY BE DEVELOPED INTO A WIDELY USED, 5HMC QUANTIFICATION ASSAY FOR RESEARCH AND CLINICAL DIAGNOSTICS. FURTHERMORE, USING THIS METHOD, WE CONFIRM THAT 5HMC IS A GOOD MOLECULAR BIOMARKER FOR DIAGNOSING COLON AND VARIOUS TYPES OF BLOOD CANCER. 2017 6 3309 34 HIGHER GENE EXPRESSION VARIABILITY IN THE MORE AGGRESSIVE SUBTYPE OF CHRONIC LYMPHOCYTIC LEUKEMIA. BACKGROUND: CHRONIC LYMPHOCYTIC LEUKEMIA (CLL) PRESENTS TWO SUBTYPES WHICH HAVE DRASTICALLY DIFFERENT CLINICAL OUTCOMES, IGVH MUTATED (M-CLL) AND IGVH UNMUTATED (U-CLL). SO FAR, THESE TWO SUBTYPES ARE NOT ASSOCIATED TO CLEAR DIFFERENCES IN GENE EXPRESSION PROFILES. INTERESTINGLY, RECENT RESULTS HAVE HIGHLIGHTED IMPORTANT ROLES FOR HETEROGENEITY, BOTH AT THE GENETIC AND AT THE EPIGENETIC LEVEL IN CLL PROGRESSION. METHODS: WE ANALYZED GENE EXPRESSION DATA OF TWO LARGE COHORTS OF CLL PATIENTS AND QUANTIFIED EXPRESSION VARIABILITY ACROSS INDIVIDUALS TO INVESTIGATE DIFFERENCES BETWEEN THE TWO SUBTYPES USING DIFFERENT MEASURES AND STATISTICAL TESTS. FUNCTIONAL SIGNIFICANCE WAS EXPLORED BY PATHWAY ENRICHMENT AND NETWORK ANALYSES. FURTHERMORE, WE IMPLEMENTED A RANDOM FOREST APPROACH BASED ON EXPRESSION VARIABILITY TO CLASSIFY PATIENTS INTO DISEASE SUBTYPES. RESULTS: WE FOUND THAT U-CLL, THE MORE AGGRESSIVE TYPE OF THE DISEASE, SHOWS SIGNIFICANTLY INCREASED VARIABILITY OF GENE EXPRESSION ACROSS PATIENTS AND THAT, OVERALL, GENES THAT SHOW HIGHER VARIABILITY IN THE AGGRESSIVE SUBTYPE ARE RELATED TO CELL CYCLE, DEVELOPMENT AND INTER-CELLULAR COMMUNICATION. THESE FUNCTIONS INDICATE A POTENTIAL RELATION BETWEEN GENE EXPRESSION VARIABILITY AND THE FASTER PROGRESSION OF THIS CLL SUBTYPE. FINALLY, A CLASSIFIER BASED ON GENE EXPRESSION VARIABILITY WAS ABLE TO CORRECTLY PREDICT THE DISEASE SUBTYPE OF CLL PATIENTS. CONCLUSIONS: THERE ARE STRONG RELATIONS BETWEEN GENE EXPRESSION VARIABILITY AND DISEASE SUBTYPE LINKING SIGNIFICANTLY INCREASED EXPRESSION VARIABILITY TO PHENOTYPES SUCH AS AGGRESSIVENESS AND RESISTANCE TO THERAPY IN CLL. 2015 7 22 23 5-HYDROXYMETHYLCYTOSINE AS A CLINICAL BIOMARKER: FLUORESCENCE-BASED ASSAY FOR HIGH-THROUGHPUT EPIGENETIC QUANTIFICATION IN HUMAN TISSUES. EPIGENETIC TRANSFORMATIONS MAY PROVIDE EARLY INDICATORS FOR CANCER AND OTHER DISEASE. SPECIFICALLY, THE AMOUNT OF GENOMIC 5-HYDROXYMETHYLCYTOSINE (5-HMC) WAS SHOWN TO BE GLOBALLY REDUCED IN A WIDE RANGE OF CANCERS. THE INTEGRATION OF THIS GLOBAL BIOMARKER INTO DIAGNOSTIC WORKFLOWS IS HAMPERED BY THE LIMITATIONS OF CURRENT 5-HMC QUANTIFICATION METHODS. HERE WE PRESENT AND VALIDATE A FLUORESCENCE-BASED PLATFORM FOR HIGH-THROUGHPUT AND COST-EFFECTIVE QUANTIFICATION OF GLOBAL GENOMIC 5-HMC LEVELS. WE UTILIZED THE ASSAY TO CHARACTERIZE CANCEROUS TISSUES BASED ON THEIR 5-HMC CONTENT, AND OBSERVED A PRONOUNCED REDUCTION IN 5-HMC LEVEL IN VARIOUS CANCER TYPES. WE PRESENT DATA FOR GLIOBLASTOMA, COLORECTAL CANCER, MULTIPLE MYELOMA, CHRONIC LYMPHOCYTIC LEUKEMIA AND PANCREATIC CANCER, COMPARED TO CORRESPONDING CONTROLS. POTENTIALLY, THE TECHNIQUE COULD ALSO BE USED TO FOLLOW RESPONSE TO TREATMENT FOR PERSONALIZED TREATMENT SELECTION. WE PRESENT INITIAL PROOF-OF-CONCEPT DATA FOR TREATMENT OF FAMILIAL ADENOMATOUS POLYPOSIS. 2020 8 2050 37 EPIGENETIC COMPONENTS OF MYALGIC ENCEPHALOMYELITIS/CHRONIC FATIGUE SYNDROME UNCOVER POTENTIAL TRANSPOSABLE ELEMENT ACTIVATION. PURPOSE: STUDIES TO DETERMINE EPIGENETIC CHANGES ASSOCIATED WITH MYALGIC ENCEPHALOMYELITIS/CHRONIC FATIGUE SYNDROME (ME/CFS) REMAIN SCARCE; HOWEVER, CURRENT EVIDENCE CLEARLY SHOWS THAT METHYLATION PATTERNS OF GENOMIC DNA AND NONCODING RNA PROFILES OF IMMUNE CELLS DIFFER BETWEEN PATIENTS AND HEALTHY SUBJECTS, SUGGESTING AN ACTIVE ROLE OF THESE EPIGENETIC MECHANISMS IN THE DISEASE. THE PRESENT STUDY COMPARES AND CONTRASTS THE AVAILABLE ME/CFS EPIGENETIC DATA IN AN EFFORT TO EVIDENCE OVERLAPPING PATHWAYS CAPABLE OF EXPLAINING AT LEAST SOME OF THE DYSFUNCTIONAL IMMUNE PARAMETERS LINKED TO THIS DISEASE. METHODS: A SYSTEMATIC SEARCH OF THE LITERATURE EVALUATING THE ME/CFS EPIGENOME LANDSCAPE WAS PERFORMED FOLLOWING THE PREFERRED REPORTING ITEMS FOR SYSTEMATIC REVIEWS AND META-ANALYSES CRITERIA. DIFFERENTIAL DNA METHYLATION AND NONCODING RNA DIFFERENTIAL EXPRESSION PATTERNS ASSOCIATED WITH ME/CFS WERE USED TO SCREEN FOR THE PRESENCE OF TRANSPOSABLE ELEMENTS USING THE DFAM BROWSER, A SEARCH PROGRAM NURTURED WITH THE REPBASE REPETITIVE SEQUENCE DATABASE AND THE REPEATMASKER ANNOTATION TOOL. FINDINGS: UNEXPECTEDLY, PARTICULAR ASSOCIATIONS OF TRANSPOSABLE ELEMENTS AND ME/CFS EPIGENETIC HALLMARKS WERE UNCOVERED. A MODEL FOR THE DISEASE EMERGED INVOLVING TRANSCRIPTIONAL INDUCTION OF ENDOGENOUS DORMANT TRANSPOSONS AND STRUCTURED CELLULAR RNA INTERACTIONS, TRIGGERING THE ACTIVATION OF THE INNATE IMMUNE SYSTEM WITHOUT A CONCOMITANT ACTIVE INFECTION. IMPLICATIONS: REPETITIVE SEQUENCE FILTERS (IE, REPEATMASKER) SHOULD BE AVOIDED WHEN ANALYZING TRANSCRIPTOMIC DATA TO ASSESS THE POTENTIAL PARTICIPATION OF REPETITIVE SEQUENCES ("JUNK REPETITIVE DNA"), REPRESENTING >45% OF THE HUMAN GENOME, IN THE ONSET AND EVOLUTION OF ME/CFS. IN ADDITION, TRANSPOSABLE ELEMENT SCREENINGS AIMED AT DESIGNING COST-EFFECTIVE, FOCUSED EMPIRICAL ASSAYS THAT CAN CONFIRM OR DISPROVE THE SUSPECTED INVOLVEMENT OF TRANSPOSON TRANSCRIPTIONAL ACTIVATION IN THIS DISEASE, FOLLOWING THE PILOT STRATEGY PRESENTED HERE, WILL REQUIRE DATABASES GATHERING LARGE ME/CFS EPIGENETIC DATASETS. 2019 9 1699 35 DYNAMIC EPIGENETIC CHANGES DURING A RELAPSE AND RECOVERY CYCLE IN MYALGIC ENCEPHALOMYELITIS/CHRONIC FATIGUE SYNDROME. MYALGIC ENCEPHALOMYELITIS/CHRONIC FATIGUE SYNDROME (ME/CFS) IS A COMPLEX DISEASE WITH VARIABLE SEVERITY. PATIENTS EXPERIENCE FREQUENT RELAPSES WHERE SYMPTOMS INCREASE IN SEVERITY, LEAVING THEM WITH A MARKED REDUCTION IN QUALITY OF LIFE. PREVIOUS WORK HAS INVESTIGATED MOLECULAR DIFFERENCES BETWEEN ME/CFS PATIENTS AND HEALTHY CONTROLS, BUT NOT THE DYNAMIC CHANGES SPECIFIC TO EACH INDIVIDUAL PATIENT. WE APPLIED PRECISION MEDICINE HERE TO MAP GENOMIC CHANGES IN TWO SELECTED ME/CFS PATIENTS THROUGH A PERIOD THAT CONTAINED A RELAPSE RECOVERY CYCLE. DNA WAS ISOLATED FROM TWO PATIENTS AND A HEALTHY AGE/GENDER MATCHED CONTROL AT REGULAR INTERVALS AND CAPTURED THE PATIENT RELAPSE IN EACH CASE. REDUCED REPRESENTATION DNA METHYLATION SEQUENCING PROFILES WERE OBTAINED SPANNING THE RELAPSE RECOVERY CYCLE. BOTH PATIENTS SHOWED A SIGNIFICANTLY LARGER METHYLOME VARIABILITY (10-20-FOLD) THROUGH THE PERIOD OF SAMPLING COMPARED WITH THE CONTROL. DURING THE RELAPSE, CHANGES IN THE METHYLOME PROFILES OF THE TWO PATIENTS WERE DETECTED IN REGULATORY-ACTIVE REGIONS OF THE GENOME THAT WERE ASSOCIATED, RESPECTIVELY, WITH 157 AND 127 DOWNSTREAM GENES, INDICATING DISTURBED METABOLIC, IMMUNE AND INFLAMMATORY FUNCTIONS. SEVERE HEALTH RELAPSES IN THE ME/CFS PATIENTS RESULTED IN FUNCTIONALLY IMPORTANT CHANGES IN THEIR DNA METHYLOMES THAT, WHILE DIFFERING BETWEEN THE TWO PATIENTS, LED TO VERY SIMILAR COMPROMISED PHYSIOLOGY. DNA METHYLATION AS A SIGNATURE OF DISEASE VARIABILITY IN ONGOING ME/CFS MAY HAVE PRACTICAL APPLICATIONS FOR STRATEGIES TO DECREASE RELAPSE FREQUENCY. 2022 10 3496 50 IDENTIFICATION OF MYALGIC ENCEPHALOMYELITIS/CHRONIC FATIGUE SYNDROME-ASSOCIATED DNA METHYLATION PATTERNS. BACKGROUND: MYALGIC ENCEPHALOMYELITIS/CHRONIC FATIGUE SYNDROME (ME/CFS) IS A COMPLEX CONDITION INVOLVING MULTIPLE ORGAN SYSTEMS AND CHARACTERIZED BY PERSISTENT/RELAPSING DEBILITATING FATIGUE, IMMUNE DYSFUNCTION, NEUROLOGICAL PROBLEMS, AND OTHER SYMPTOMS NOT CURABLE FOR AT LEAST 6 MONTHS. DISRUPTION OF DNA METHYLATION PATTERNS HAS BEEN TIED TO VARIOUS IMMUNE AND NEUROLOGICAL DISEASES; HOWEVER, ITS STATUS IN ME/CFS REMAINS UNCERTAIN. OUR STUDY AIMED AT IDENTIFYING CHANGES IN THE DNA METHYLATION PATTERNS THAT ASSOCIATE WITH ME/CFS. METHODS: WE EXTRACTED GENOMIC DNA FROM PERIPHERAL BLOOD MONONUCLEAR CELLS FROM 13 ME/CFS STUDY SUBJECTS AND 12 HEALTHY CONTROLS AND MEASURED GLOBAL DNA METHYLATION BY ELISA-LIKE METHOD AND SITE-SPECIFIC METHYLATION STATUS USING ILLUMINA METHYLATIONEPIC MICROARRAYS. PYROSEQUENCING VALIDATION INCLUDED 33 ME/CFS CASES AND 31 CONTROLS FROM TWO GEOGRAPHICALLY DISTANT COHORTS. RESULTS: GLOBAL DNA METHYLATION LEVELS OF ME/CFS CASES WERE SIMILAR TO THOSE OF CONTROLS. HOWEVER, MICROARRAY-BASED APPROACH ALLOWED DETECTION OF 17,296 DIFFERENTIALLY METHYLATED CPG SITES IN 6,368 GENES ACROSS REGULATORY ELEMENTS AND WITHIN CODING REGIONS OF GENES. ANALYSIS OF DNA METHYLATION IN PROMOTER REGIONS REVEALED 307 DIFFERENTIALLY METHYLATED PROMOTERS. INGENUITY PATHWAY ANALYSIS INDICATED THAT GENES ASSOCIATED WITH DIFFERENTIALLY METHYLATED PROMOTERS PARTICIPATED IN AT LEAST 15 DIFFERENT PATHWAYS MOSTLY RELATED TO CELL SIGNALING WITH A STRONG IMMUNE COMPONENT. CONCLUSIONS: THIS IS THE FIRST STUDY THAT HAS EXPLORED GENOME-WIDE EPIGENETIC CHANGES ASSOCIATED WITH ME/CFS USING THE ADVANCED ILLUMINA METHYLATIONEPIC MICROARRAYS COVERING ABOUT 850,000 CPG SITES IN TWO GEOGRAPHICALLY DISTANT COHORTS OF ME/CFS CASES AND MATCHED CONTROLS. OUR RESULTS ARE ALIGNED WITH PREVIOUS STUDIES THAT INDICATE A DYSREGULATION OF THE IMMUNE SYSTEM IN ME/CFS. THEY ALSO SUGGEST A POTENTIAL ROLE OF EPIGENETIC DE-REGULATION IN THE PATHOBIOLOGY OF ME/CFS. WE PROPOSE SCREENING OF LARGER COHORTS OF ME/CFS CASES TO DETERMINE THE EXTERNAL VALIDITY OF THESE EPIGENETIC CHANGES IN ORDER TO IMPLEMENT THEM AS POSSIBLE DIAGNOSTIC MARKERS IN CLINICAL SETTING. 2018 11 3989 42 LONGITUDINAL ANALYSIS OF BLOOD DNA METHYLATION IDENTIFIES MECHANISMS OF RESPONSE TO TUMOR NECROSIS FACTOR INHIBITOR THERAPY IN RHEUMATOID ARTHRITIS. BACKGROUND: RHEUMATOID ARTHRITIS (RA) IS A CHRONIC, IMMUNE-MEDIATED INFLAMMATORY DISEASE OF THE JOINTS THAT HAS BEEN ASSOCIATED WITH VARIATION IN THE PERIPHERAL BLOOD METHYLOME. IN THIS STUDY, WE AIM TO IDENTIFY EPIGENETIC VARIATION THAT IS ASSOCIATED WITH THE RESPONSE TO TUMOR NECROSIS FACTOR INHIBITOR (TNFI) THERAPY. METHODS: PERIPHERAL BLOOD GENOME-WIDE DNA METHYLATION PROFILES WERE ANALYZED IN A DISCOVERY COHORT OF 62 RA PATIENTS AT BASELINE AND AT WEEK 12 OF TNFI THERAPY. DNA METHYLATION OF INDIVIDUAL CPG SITES AND ENRICHMENT OF BIOLOGICAL PATHWAYS WERE EVALUATED FOR THEIR ASSOCIATION WITH DRUG RESPONSE. USING A NOVEL CELL DECONVOLUTION APPROACH, ALTERED DNA METHYLATION ASSOCIATED WITH TNFI RESPONSE WAS ALSO TESTED IN THE SIX MAIN IMMUNE CELL TYPES IN BLOOD. VALIDATION OF THE RESULTS WAS PERFORMED IN AN INDEPENDENT LONGITUDINAL COHORT OF 60 RA PATIENTS. FINDINGS: TREATMENT WITH TNFI WAS ASSOCIATED WITH SIGNIFICANT LONGITUDINAL PERIPHERAL BLOOD METHYLATION CHANGES IN BIOLOGICAL PATHWAYS RELATED TO RA (FDR<0.05). 139 BIOLOGICAL FUNCTIONS WERE MODIFIED BY THERAPY, WITH METHYLATION LEVELS CHANGING SYSTEMATICALLY TOWARDS A SIGNATURE SIMILAR TO THAT OF HEALTHY CONTROLS. DIFFERENCES IN THE METHYLATION PROFILE OF T CELL ACTIVATION AND DIFFERENTIATION, GTPASE-MEDIATED SIGNALING, AND ACTIN FILAMENT ORGANIZATION PATHWAYS WERE ASSOCIATED WITH THE CLINICAL RESPONSE TO THERAPY. CELL TYPE DECONVOLUTION ANALYSIS IDENTIFIED CPG SITES IN CD4+T, NK, NEUTROPHILS AND MONOCYTES THAT WERE SIGNIFICANTLY ASSOCIATED WITH THE RESPONSE TO TNFI. INTERPRETATION: OUR RESULTS SHOW THAT TREATMENT WITH TNFI RESTORES HOMEOSTATIC BLOOD METHYLATION IN RA. THE CLINICAL RESPONSE TO TNFI IS ASSOCIATED TO METHYLATION VARIATION IN SPECIFIC BIOLOGICAL PATHWAYS, AND IT INVOLVES CELLS FROM BOTH THE INNATE AND ADAPTIVE IMMUNE SYSTEMS. FUNDING: THE INSTITUTO DE SALUD CARLOS III. 2022 12 1068 26 CLL INTRACLONAL FRACTIONS EXHIBIT ESTABLISHED AND RECENTLY ACQUIRED PATTERNS OF DNA METHYLATION. INTRACLONAL SUBPOPULATIONS OF CIRCULATING CHRONIC LYMPHOCYTIC LEUKEMIA (CLL) CELLS WITH DIFFERENT PROLIFERATIVE HISTORIES AND RECIPROCAL SURFACE EXPRESSION OF CXCR4 AND CD5 HAVE BEEN OBSERVED IN THE PERIPHERAL BLOOD OF CLL PATIENTS AND NAMED PROLIFERATIVE (PF), INTERMEDIATE (IF), AND RESTING (RF) CELLULAR FRACTIONS. HERE, WE FOUND THAT THESE INTRACLONAL CIRCULATING FRACTIONS SHARE PERSISTENT DNA METHYLATION SIGNATURES LARGELY ASSOCIATED WITH THE MUTATION STATUS OF THE IMMUNOGLOBULIN HEAVY CHAIN LOCUS (IGHV) AND THEIR ORIGINS FROM DISTINCT STAGES OF DIFFERENTIATION OF ANTIGEN-EXPERIENCED B CELLS. INCREASED LEUKEMIC BIRTH RATE, HOWEVER, SHOWED A VERY LIMITED IMPACT ON DNA METHYLATION OF CIRCULATING CLL FRACTIONS INDEPENDENT OF IGHV MUTATION STATUS. ADDITIONALLY, DNA METHYLATION HETEROGENEITY INCREASED AS LEUKEMIC CELLS ADVANCED FROM PF TO RF IN THE PERIPHERAL BLOOD. THIS FREQUENTLY CO-OCCURRED WITH HETEROCHROMATIN HYPOMETHYLATION AND HYPERMETHYLATION OF POLYCOMB-REPRESSED REGIONS IN THE PF, SUGGESTING ACCUMULATION OF LONGEVITY-ASSOCIATED EPIGENETIC FEATURES IN RECENTLY BORN CELLS. ON THE OTHER HAND, TRANSCRIPTIONAL DIFFERENCES BETWEEN PAIRED INTRACLONAL FRACTIONS CONFIRMED THEIR PROLIFERATIVE EXPERIENCE AND FURTHER SUPPORTED A LINEAR ADVANCEMENT FROM PF TO RF IN THE PERIPHERAL BLOOD. SEVERAL OF THESE DIFFERENTIALLY EXPRESSED GENES SHOWED UNIQUE ASSOCIATIONS WITH CLINICAL OUTCOME NOT EVIDENT IN THE BULK CLONE, SUPPORTING THE PATHOLOGICAL AND THERAPEUTIC RELEVANCE OF STUDYING INTRACLONAL CLL FRACTIONS. WE CONCLUDE THAT INDEPENDENT METHYLATION AND TRANSCRIPTIONAL LANDSCAPES REFLECT BOTH PREEXISTING CELL-OF-ORIGIN FINGERPRINTS AND MORE RECENTLY ACQUIRED HALLMARKS ASSOCIATED WITH THE LIFE CYCLE OF CIRCULATING CLL CELLS. 2020 13 1577 31 DNA METHYLATION PROFILE IN CHRONIC MYELOMONOCYTIC LEUKEMIA ASSOCIATES WITH DISTINCT CLINICAL, BIOLOGICAL AND GENETIC FEATURES. CHROMOSOMAL ABNORMALITIES ARE DETECTED IN 20-30% OF PATIENTS WITH CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML) AND CORRELATE WITH PROGNOSIS. ON THE MUTATION LEVEL, DISRUPTIVE ALTERATIONS ARE PARTICULARLY FREQUENT IN CHROMATIN REGULATORY GENES. HOWEVER, LITTLE IS KNOWN ABOUT THE CONSEQUENTIAL ALTERATIONS IN THE EPIGENETIC MARKING OF THE GENOME. HERE, WE REPORT THE ANALYSIS OF GENOMIC DNA METHYLATION PATTERNS OF 64 CMML PATIENTS AND 10 HEALTHY CONTROLS, USING A DNA METHYLATION MICROARRAY FOCUSED ON PROMOTER REGIONS. DIFFERENTIAL METHYLATION ANALYSIS BETWEEN PATIENTS AND CONTROLS ALLOWED US TO IDENTIFY ABNORMALITIES IN DNA METHYLATION, INCLUDING HYPERMETHYLATION OF SPECIFIC GENES AND LARGE GENOME REGIONS WITH ABERRANT DNA METHYLATION. UNSUPERVISED HIERARCHICAL CLUSTER ANALYSIS IDENTIFIED TWO MAIN CLUSTERS THAT ASSOCIATED WITH THE CLINICAL, BIOLOGICAL, AND GENETIC FEATURES OF PATIENTS. GROUP 1 WAS ENRICHED IN PATIENTS WITH ADVERSE CLINICAL AND BIOLOGICAL CHARACTERISTICS AND POORER OVERALL AND PROGRESSION-FREE SURVIVAL. IN ADDITION, SIGNIFICANT DIFFERENCES IN DNA METHYLATION WERE OBSERVED BETWEEN PATIENTS WITH LOW RISK AND INTERMEDIATE/HIGH RISK KARYOTYPES AND BETWEEN TET2 MUTANT AND WILD TYPE PATIENTS. TAKEN TOGETHER, OUR RESULTS DEMONSTRATE THAT ALTERED DNA METHYLATION PATTERNS REFLECT THE CMML DISEASE STATE AND ALLOW TO IDENTIFY PATIENT GROUPS WITH DISTINCT CLINICAL FEATURES. 2018 14 18 29 5-AZACYTIDINE MODULATES CPG METHYLATION LEVELS OF EZH2 AND NOTCH1 IN MYELODYSPLASTIC SYNDROMES. PURPOSE: MOLECULAR MECHANISMS OF RESPONSE TO HYPOMETHYLATING AGENTS IN PATIENTS WITH MYELODYSPLASTIC SYNDROMES (MDS) AND CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML) STILL REMAIN LARGELY UNKNOWN. THEREFORE, THE EFFECTS OF 5-AZACYTIDINE (AZA) ON CLONAL ARCHITECTURE AND DNA METHYLATION WERE INVESTIGATED IN THIS STUDY. METHODS: USING NEXT-GENERATION SEQUENCING (NGS), 30 MYELOID LEUKEMIA-ASSOCIATED GENES WERE ANALYZED IN 15 MDS/CMML PATIENTS WITH EXCELLENT RESPONSE TO AZA. EFFECTS ON METHYLATION LEVELS WERE ANALYZED BY QUANTITATIVE METHYLATION ANALYSIS USING PYROSEQUENCING FOR THE GLOBAL METHYLATION MARKER LINE-1 IN PATIENTS AND MYELOID CELL LINES. VARIOUS MYELOID CELL LINES AND A HEALTHY COHORT WERE SCREENED FOR METHYLATION LEVELS IN 23 GENES. SELECTED TARGETS WERE VERIFIED ON THE MDS/CMML COHORT. RESULTS: THE STUDY PRESENTED HERE SHOWED A STABLE VARIANT ALLELE FREQUENCY AND STABLE GLOBAL METHYLATION LEVELS IN RESPONDING PATIENTS. A SIGNIFICANT DEMETHYLATION OF EZH2 AND NOTCH1 WAS REVEALED IN PATIENTS WITH AZA RESPONSE. CONCLUSIONS: A RESPONSE TO AZA IS NOT ASSOCIATED WITH ERADICATION OF MALIGNANT CLONES, BUT RATHER WITH A STABILIZATION OF THE CLONAL ARCHITECTURE. WE SUGGEST CHANGES IN CPG METHYLATION LEVELS OF EZH2 AND NOTCH1 AS POTENTIAL TARGETS OF EPIGENETIC RESPONSE TO AZA TREATMENT WHICH MAY ALSO SERVE AS USEFUL BIOMARKERS AFTER CLINICAL EVALUATION. 2019 15 3132 42 GLOBAL DISTRIBUTION OF DNA HYDROXYMETHYLATION AND DNA METHYLATION IN CHRONIC LYMPHOCYTIC LEUKEMIA. BACKGROUND: CHRONIC LYMPHOCYTIC LEUKEMIA (CLL) HAS BEEN A GOOD MODEL SYSTEM TO UNDERSTAND THE FUNCTIONAL ROLE OF 5-METHYLCYTOSINE (5-MC) IN CANCER PROGRESSION. MORE RECENTLY, AN OXIDIZED FORM OF 5-MC, 5-HYDROXYMETHYLCYTOSINE (5-HMC) HAS GAINED LOT OF ATTENTION AS A REGULATORY EPIGENETIC MODIFICATION WITH PROGNOSTIC AND DIAGNOSTIC IMPLICATIONS FOR SEVERAL CANCERS. HOWEVER, THERE IS NO GLOBAL STUDY EXPLORING THE ROLE OF 5-HYDROXYMETHYLCYTOSINE (5-HMC) LEVELS IN CLL. HEREIN, USING MASS SPECTROMETRY AND HMEDIP-SEQUENCING, WE ANALYSED THE DYNAMICS OF 5-HMC DURING B CELL MATURATION AND CLL PATHOGENESIS. RESULTS: WE SHOW THAT NAIVE B-CELLS HAD HIGHER LEVELS OF 5-HMC AND 5-MC COMPARED TO NON-CLASS SWITCHED AND CLASS-SWITCHED MEMORY B-CELLS. WE FOUND A SIGNIFICANT DECREASE IN GLOBAL 5-MC LEVELS IN CLL PATIENTS (N = 15) COMPARED TO NAIVE AND MEMORY B CELLS, WITH NO CHANGES DETECTED BETWEEN THE CLL PROGNOSTIC GROUPS. ON THE OTHER HAND, GLOBAL 5-HMC LEVELS OF CLL PATIENTS WERE SIMILAR TO MEMORY B CELLS AND REDUCED COMPARED TO NAIVE B CELLS. INTERESTINGLY, 5-HMC LEVELS WERE INCREASED AT REGULATORY REGIONS SUCH AS GENE-BODY, CPG ISLAND SHORES AND SHELVES AND 5-HMC DISTRIBUTION OVER THE GENE-BODY POSITIVELY CORRELATED WITH DEGREE OF TRANSCRIPTIONAL ACTIVITY. IMPORTANTLY, CLL SAMPLES SHOWED ABERRANT 5-HMC AND 5-MC PATTERN OVER GENE-BODY COMPARED TO WELL-DEFINED PATTERNS IN NORMAL B-CELLS. INTEGRATED ANALYSIS OF 5-HMC AND RNA-SEQUENCING FROM CLL DATASETS IDENTIFIED THREE NOVEL ONCOGENIC DRIVERS THAT COULD HAVE POTENTIAL ROLES IN CLL DEVELOPMENT AND PROGRESSION. CONCLUSIONS: THUS, OUR STUDY SUGGESTS THAT THE GLOBAL LOSS OF 5-HMC, ACCOMPANIED BY ITS SIGNIFICANT INCREASE AT THE GENE REGULATORY REGIONS, CONSTITUTE A NOVEL HALLMARK OF CLL PATHOGENESIS. OUR COMBINED ANALYSIS OF 5-MC AND 5-HMC SEQUENCING PROVIDED INSIGHTS INTO THE POTENTIAL ROLE OF 5-HMC IN MODULATING GENE EXPRESSION CHANGES DURING CLL PATHOGENESIS. 2019 16 6613 29 ULTRADEEP BISULFITE SEQUENCING ANALYSIS OF DNA METHYLATION PATTERNS IN MULTIPLE GENE PROMOTERS BY 454 SEQUENCING. WE DEVELOPED A NOVEL APPROACH FOR CONDUCTING MULTISAMPLE, MULTIGENE, ULTRADEEP BISULFITE SEQUENCING ANALYSIS OF DNA METHYLATION PATTERNS IN CLINICAL SAMPLES. A MASSIVELY PARALLEL SEQUENCING-BY-SYNTHESIS METHOD (454 SEQUENCING) WAS USED TO DIRECTLY SEQUENCE >100 BISULFITE PCR PRODUCTS IN A SINGLE SEQUENCING RUN WITHOUT SUBCLONING. WE SHOWED THE UTILITY, ROBUSTNESS, AND SUPERIORITY OF THIS APPROACH BY ANALYZING METHYLATION IN 25 GENE-RELATED CPG RICH REGIONS FROM >40 CASES OF PRIMARY CELLS, INCLUDING NORMAL PERIPHERAL BLOOD LYMPHOCYTES, ACUTE LYMPHOBLASTIC LEUKEMIA (ALL), CHRONIC LYMPHOCYTIC LEUKEMIA (CLL), FOLLICULAR LYMPHOMA (FL), AND MANTLE CELL LYMPHOMA (MCL). A TOTAL OF 294,631 SEQUENCES WAS GENERATED WITH AN AVERAGE READ LENGTH OF 131 BP. ON AVERAGE, >1,600 INDIVIDUAL SEQUENCES WERE GENERATED FOR EACH PCR AMPLICON FAR BEYOND THE FEW CLONES (<20) TYPICALLY ANALYZED BY TRADITIONAL BISULFITE SEQUENCING. COMPREHENSIVE ANALYSIS OF CPG METHYLATION PATTERNS AT A SINGLE DNA MOLECULE LEVEL USING CLUSTERING ALGORITHMS REVEALED DIFFERENTIAL METHYLATION PATTERNS BETWEEN DISEASES. A SIGNIFICANT INCREASE IN METHYLATION WAS DETECTED IN ALL AND FL SAMPLES COMPARED WITH CLL AND MCL. FURTHERMORE, A PROGRESSIVE SPREADING OF METHYLATION WAS DETECTED FROM THE PERIPHERY TOWARD THE CENTER OF SELECT CPG ISLANDS IN THE ALL AND FL SAMPLES. THE ULTRADEEP SEQUENCING ALSO ALLOWED SIMULTANEOUS ANALYSIS OF GENETIC AND EPIGENETIC DATA AND REVEALED AN ASSOCIATION BETWEEN A SINGLE NUCLEOTIDE POLYMORPHISM AND THE METHYLATION PRESENT IN THE LRP1B PROMOTER. THIS NEW GENERATION OF METHYLOME SEQUENCING WILL PROVIDE DIGITAL PROFILES OF ABERRANT DNA METHYLATION FOR INDIVIDUAL HUMAN CANCERS AND OFFERS A ROBUST METHOD FOR THE EPIGENETIC CLASSIFICATION OF TUMOR SUBTYPES. 2007 17 2207 52 EPIGENETIC MODIFICATIONS AND GLUCOCORTICOID SENSITIVITY IN MYALGIC ENCEPHALOMYELITIS/CHRONIC FATIGUE SYNDROME (ME/CFS). BACKGROUND: MYALGIC ENCEPHALOMYELITIS/CHRONIC FATIGUE SYNDROME (ME/CFS) IS A DEBILITATING IDIOPATHIC DISEASE CHARACTERIZED BY UNEXPLAINED FATIGUE THAT FAILS TO RESOLVE WITH SUFFICIENT REST. DIAGNOSIS IS BASED ON A LIST OF SYMPTOMS AND EXCLUSION OF OTHER FATIGUE-RELATED HEALTH CONDITIONS. DESPITE A HETEROGENEOUS PATIENT POPULATION, IMMUNE AND HYPOTHALAMIC-PITUITARY-ADRENAL (HPA) AXIS FUNCTION DIFFERENCES, SUCH AS ENHANCED NEGATIVE FEEDBACK TO GLUCOCORTICOIDS, ARE RECURRING FINDINGS IN ME/CFS STUDIES. EPIGENETIC MODIFICATIONS, SUCH AS CPG METHYLATION, ARE KNOWN TO REGULATE LONG-TERM PHENOTYPIC DIFFERENCES AND PREVIOUS WORK BY OUR GROUP FOUND DNA METHYLOME DIFFERENCES IN ME/CFS, HOWEVER THE RELATIONSHIP BETWEEN DNA METHYLOME MODIFICATIONS, CLINICAL AND FUNCTIONAL CHARACTERISTICS ASSOCIATED WITH ME/CFS HAS NOT BEEN EXAMINED. METHODS: WE EXAMINED THE DNA METHYLOME IN PERIPHERAL BLOOD MONONUCLEAR CELLS (PBMCS) OF A LARGER COHORT OF FEMALE ME/CFS PATIENTS USING THE ILLUMINA HUMANMETHYLATION450 BEADCHIP ARRAY. IN PARALLEL TO THE DNA METHYLOME ANALYSIS, WE INVESTIGATED IN VITRO GLUCOCORTICOID SENSITIVITY DIFFERENCES BY STIMULATING PBMCS WITH PHYTOHAEMAGGLUTININ AND SUPPRESSED GROWTH WITH DEXAMETHASONE. WE EXPLORED DNA METHYLATION DIFFERENCES USING BISULFITE PYROSEQUENCING AND STATISTICAL PERMUTATION. LINEAR REGRESSION WAS IMPLEMENTED TO DISCOVER EPIGENOMIC REGIONS ASSOCIATED WITH SELF-REPORTED QUALITY OF LIFE AND NETWORK ANALYSIS OF GENE ONTOLOGY TERMS TO BIOLOGICALLY CONTEXTUALIZE RESULTS. RESULTS: WE DETECTED 12,608 DIFFERENTIALLY METHYLATED SITES BETWEEN ME/CFS PATIENTS AND HEALTHY CONTROLS PREDOMINANTLY LOCALIZED TO CELLULAR METABOLISM GENES, SOME OF WHICH WERE ALSO RELATED TO SELF-REPORTED QUALITY OF LIFE HEALTH SCORES. AMONG ME/CFS PATIENTS, GLUCOCORTICOID SENSITIVITY WAS ASSOCIATED WITH DIFFERENTIAL METHYLATION AT 13 LOCI. CONCLUSIONS: OUR RESULTS INDICATE DNA METHYLATION MODIFICATIONS IN CELLULAR METABOLISM IN ME/CFS DESPITE A HETEROGENEOUS PATIENT POPULATION, IMPLICATING THESE PROCESSES IN IMMUNE AND HPA AXIS DYSFUNCTION IN ME/CFS. MODIFICATIONS TO EPIGENETIC LOCI ASSOCIATED WITH DIFFERENCES IN GLUCOCORTICOID SENSITIVITY MAY BE IMPORTANT AS BIOMARKERS FOR FUTURE CLINICAL TESTING. OVERALL, THESE FINDINGS ALIGN WITH RECENT ME/CFS WORK THAT POINT TOWARDS IMPAIRMENT IN CELLULAR ENERGY PRODUCTION IN THIS PATIENT POPULATION. 2017 18 1026 48 CIRCULATING MIRNAS EXPRESSION IN MYALGIC ENCEPHALOMYELITIS/CHRONIC FATIGUE SYNDROME. MYALGIC ENCEPHALOMYELITIS/CHRONIC FATIGUE SYNDROME (ME/CFS) IS A COMPLEX MULTIFACTORIAL DISEASE THAT CAUSES INCREASING MORBIDITY WORLDWIDE, AND MANY INDIVIDUALS WITH ME/CFS SYMPTOMS REMAIN UNDIAGNOSED DUE TO THE LACK OF DIAGNOSTIC BIOMARKERS. ITS ETIOLOGY IS STILL UNKNOWN, BUT INCREASING EVIDENCE SUPPORTS A ROLE OF HERPESVIRUSES (INCLUDING HHV-6A AND HHV-6B) AS POTENTIAL TRIGGERS. INTERESTINGLY, THE INFECTION BY THESE VIRUSES HAS BEEN REPORTED TO IMPACT THE EXPRESSION OF MICRORNAS (MIRNAS), SHORT NON-CODING RNA SEQUENCES WHICH HAVE BEEN SUGGESTED TO BE EPIGENETIC FACTORS MODULATING ME/CFS PATHOGENIC MECHANISMS. NOTABLY, THE PRESENCE OF CIRCULATING MIRNAS IN PLASMA HAS RAISED THE POSSIBILITY TO USE THEM AS VALUABLE BIOMARKERS FOR DISTINGUISHING ME/CFS PATIENTS FROM HEALTHY CONTROLS. THUS, THIS STUDY AIMED AT DETERMINING THE ROLE OF EIGHT MIRNAS, WHICH WERE SELECTED FOR THEIR PREVIOUS ASSOCIATION WITH ME/CFS, AS POTENTIAL CIRCULATING BIOMARKERS OF THE DISEASE. THEIR PRESENCE WAS QUANTITATIVELY EVALUATED IN PLASMA FROM 40 ME/CFS PATIENTS AND 20 HEALTHY CONTROLS BY SPECIFIC TAQMAN ASSAYS, AND THE RESULTS SHOWED THAT SIX OUT OF THE EIGHT OF THE SELECTED MIRNAS WERE DIFFERENTLY EXPRESSED IN PATIENTS COMPARED TO CONTROLS; MORE SPECIFICALLY, FIVE MIRNAS WERE SIGNIFICANTLY UPREGULATED (MIR-127-3P, MIR-142-5P, MIR-143-3P, MIR-150-5P, AND MIR-448), AND ONE WAS DOWNMODULATED (MIR-140-5P). MIRNA LEVELS DIRECTLY CORRELATED WITH DISEASE SEVERITY, WHEREAS NO SIGNIFICANT CORRELATIONS WERE OBSERVED WITH THE PLASMA LEVELS OF SEVEN PRO-INFLAMMATORY CYTOKINES OR WITH THE PRESENCE/LOAD OF HHV-6A/6B GENOME, AS JUDGED BY SPECIFIC PCR AMPLIFICATION. THE RESULTS MAY OPEN THE WAY FOR FURTHER VALIDATION OF MIRNAS AS NEW POTENTIAL BIOMARKERS IN ME/CFS AND INCREASE THE KNOWLEDGE OF THE COMPLEX PATHWAYS INVOLVED IN THE ME/CFS DEVELOPMENT. 2023 19 70 29 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 20 2639 23 EPIGENOMIC ANALYSIS DETECTS WIDESPREAD GENE-BODY DNA HYPOMETHYLATION IN CHRONIC LYMPHOCYTIC LEUKEMIA. WE HAVE EXTENSIVELY CHARACTERIZED THE DNA METHYLOMES OF 139 PATIENTS WITH CHRONIC LYMPHOCYTIC LEUKEMIA (CLL) WITH MUTATED OR UNMUTATED IGHV AND OF SEVERAL MATURE B-CELL SUBPOPULATIONS THROUGH THE USE OF WHOLE-GENOME BISULFITE SEQUENCING AND HIGH-DENSITY MICROARRAYS. THE TWO MOLECULAR SUBTYPES OF CLL HAVE DIFFERING DNA METHYLOMES THAT SEEM TO REPRESENT EPIGENETIC IMPRINTS FROM DISTINCT NORMAL B-CELL SUBPOPULATIONS. DNA HYPOMETHYLATION IN THE GENE BODY, TARGETING MOSTLY ENHANCER SITES, WAS THE MOST FREQUENT DIFFERENCE BETWEEN NAIVE AND MEMORY B CELLS AND BETWEEN THE TWO MOLECULAR SUBTYPES OF CLL AND NORMAL B CELLS. ALTHOUGH DNA METHYLATION AND GENE EXPRESSION WERE POORLY CORRELATED, WE IDENTIFIED GENE-BODY CPG DINUCLEOTIDES WHOSE METHYLATION WAS POSITIVELY OR NEGATIVELY ASSOCIATED WITH EXPRESSION. WE HAVE ALSO RECOGNIZED A DNA METHYLATION SIGNATURE THAT DISTINGUISHES NEW CLINICO-BIOLOGICAL SUBTYPES OF CLL. WE PROPOSE AN EPIGENOMIC SCENARIO IN WHICH DIFFERENTIAL METHYLATION IN THE GENE BODY MAY HAVE FUNCTIONAL AND CLINICAL IMPLICATIONS IN LEUKEMOGENESIS. 2012