1 1273 137 CYTOTOXIC PERIPHERAL T-CELL LYMPHOMAS AND EBV-POSITIVE T/NK-CELL LYMPHOPROLIFERATIVE DISEASES: EMERGING CONCEPTS, RECENT ADVANCES, AND THE PUTATIVE ROLE OF CLONAL HEMATOPOIESIS. A REPORT OF THE 2022 EA4HP/SH LYMPHOMA WORKSHOP. CYTOTOXIC PERIPHERAL T-CELL LYMPHOMAS AND EBV-POSITIVE T/NK-CELL LYMPHOPROLIFERATIVE DISEASES WERE DISCUSSED AT THE 2022 EUROPEAN ASSOCIATION FOR HAEMATOPATHOLOGY/SOCIETY FOR HEMATOPATHOLOGY LYMPHOMA WORKSHOP HELD IN FLORENCE, ITALY. THIS SESSION FOCUSED ON (I) PRIMARY NODAL EBV-POSITIVE T AND NK-CELL LYMPHOMAS (PRIMARY NODAL-EBV-TNKL), (II) EXTRANODAL EBV-POSITIVE T/NK LYMPHOPROLIFERATIVE DISEASES (LPD) IN CHILDREN AND ADULTS, (III) CYTOTOXIC PERIPHERAL T-CELL LYMPHOMAS, NOS (CPTCL-NOS), EBV-NEGATIVE, AND (IV) MISCELLANEOUS CASES. PRIMARY NODAL-EBV-TNKL IS A NEWLY RECOGNIZED ENTITY WHICH IS RARE, AGGRESSIVE, AND ASSOCIATED WITH UNDERLYING IMMUNE DEFICIENCY/IMMUNE DYSREGULATION. ALL CASES PRESENTED WITH LYMPHADENOPATHY BUT SOME DEMONSTRATED INVOLVEMENT OF TONSIL/WALDEYER'S RING AND EXTRANODAL SITES. THE MAJORITY OF TUMORS ARE OF T-CELL LINEAGE, AND THE MOST FREQUENT MUTATIONS INVOLVE THE EPIGENETIC MODIFIER GENES, SUCH AS TET2 AND DNMT3A, AND JAK-STAT GENES. A SPECTRUM OF EBV-POSITIVE T/NK LPD INVOLVING EXTRANODAL SITES WERE DISCUSSED AND HIGHLIGHT THE DIAGNOSTIC CHALLENGE WITH PRIMARY NODAL-EBV-TNKL WHEN THESE EXTRANODAL EBV-POSITIVE T/NK LPD CASES DEMONSTRATE PREDOMINANT NODAL DISEASE EITHER AT PRESENTATION OR DURING DISEASE PROGRESSION FROM CHRONIC ACTIVE EBV DISEASE. THE MAJORITY OF CPTCL-NOS DEMONSTRATED THE TBX21 PHENOTYPE. SOME CASES HAD A BACKGROUND OF IMMUNOSUPPRESSION OR IMMUNE DYSREGULATION. INTERESTINGLY, AN UNEXPECTED ASSOCIATION OF CPTCL-NOS, EBV-POSITIVE AND NEGATIVE, WITH TFH LYMPHOMAS/LPDS WAS OBSERVED IN THE WORKSHOP CASES. SIMILAR TO A PUBLISHED LITERATURE, THE GENETIC LANDSCAPE OF CPTCL-NOS FROM THE WORKSHOP SHOWED FREQUENT MUTATIONS IN EPIGENETIC MODIFIERS, INCLUDING TET2 AND DNMT3A, SUGGESTING A ROLE OF CLONAL HEMATOPOIESIS IN THE DISEASE PATHOGENESIS. 2023 2 1420 31 DIFFERENT PATTERNS OF ACETYLATION AND DIMETHYLATION OF HISTONE H3 BETWEEN YOUNG AND AGED CASES WITH CHRONIC TONSILLITIS: INFLUENCES OF INFLAMMATION AND AGING. INTRODUCTION: EPIGENETICS IS NOW CONSIDERED TO BE CRUCIALLY INVOLVED IN NORMAL GENETICS AND DIFFERENTIATION AND IN PATHOLOGICAL CONDITIONS, SUCH AS CANCER, AGING, AND INFLAMMATION. EPIGENETIC MECHANISMS INVOLVE DNA METHYLATION AND HISTONE MODIFICATIONS. THE PURPOSE OF THIS STUDY WAS TO INVESTIGATE THE EFFECTS OF INFLAMMATION ON EPIGENETICS IN YOUNG SUBJECTS AND THE EFFECT OF AGING. MATERIALS AND METHODS: THE PALATINE TONSILS WERE EXTRACTED FROM CHILD AND ADULT PATIENTS WITH CHRONIC TONSILLITIS. HEMATOXYLIN-EOSIN STAINING WAS PERFORMED TO EXAMINE THE MORPHOLOGY OF THE PALATINE TONSILS. A FLUORESCENCE IMMUNOLOGICAL EXAMINATION WAS ALSO PERFORMED TO DETECT ACETYL-HISTONE H3 OR DIMETHYL-HISTONE H3. CONFOCAL SCANNING MICROSCOPY WAS USED FOR OBSERVATIONS. RESULTS: ACETYLATED HISTONE H3 WAS DETECTED IN TONSILS FROM CHILD PATIENTS BUT NOT FROM ADULT PATIENTS. DIMETHYLATED HISTONE H3 WAS NOT DETECTED IN TONSILS FROM EITHER GROUP OF PATIENTS. DEGENERATION OF THE TONSILLAR STRUCTURES WAS APPARENT IN TONSILS FROM ADULT PATIENTS. DISCUSSION: THE DIFFERENTIAL EXPRESSION OF ACETYLATED HISTONE H3 LYS9 MAY REFLECT IMMUNOLOGICAL DIFFERENCES BETWEEN YOUNG AND AGED TONSILS. THE DECREASE OBSERVED IN THE ACTIVITY OF HISTONE METHYLTRANSFERASE INDUCED THE DOWN-REGULATED EXPRESSION OF METHYLATED HISTONE H3. CONCLUSION: OUR RESULTS SUGGEST THAT EPIGENETIC CHANGES PARTICIPATE IN CHRONIC INFLAMMATION AND AGING IN THE PALATINE TONSILS. ALTHOUGH THE RESULTS DO NOT LEAD TO A DIRECT TREATMENT, THE EPIGENETIC PATHOGENESIS OF CHRONIC INFLAMMATION, SUCH AS IMMUNOGLOBULIN A NEPHROPATHY, BY FOCAL INFECTIONS WILL BE DESCRIBED IN GREATER DETAIL IN FUTURE STUDIES, WHICH WILL LEAD TO NEW TREATMENTS BEING DEVELOPED. 2016 3 1775 43 EBV IN T-/NK-CELL TUMORIGENESIS. EPSTEIN-BARR VIRUS (EBV), WHICH IS ASSOCIATED WITH B-CELL PROLIFERATIVE DISORDERS, ALSO TRANSFORMS T- OR NATURAL KILLER (NK)-LINEAGE CELLS AND HAS BEEN CONNECTED WITH VARIOUS T- OR NK (T/NK)-CELL MALIGNANCIES, SUCH AS EXTRANODAL NK/T-CELL LYMPHOMA-NASAL TYPE AND AGGRESSIVE NK-CELL LEUKEMIA. CHRONIC ACTIVE EBV (CAEBV) DISEASE , WHICH OCCURS MOST OFTEN IN CHILDREN AND YOUNG ADULTS IN EAST ASIA, IS AN EBV-ASSOCIATED T-/NK-CELL LYMPHOPROLIFERATIVE DISEASE. PATIENTS WITH CAEBV OFTEN PROGRESS TO OVERT LYMPHOMA OR LEUKEMIA OVER A LONG-TERM CLINICAL COURSE. EBV'S TRANSFORMING CAPACITY IN B CELLS IS WELL CHARACTERIZED, BUT THE MOLECULAR PATHOGENESIS OF CLONAL EXPANSION CAUSED BY EBV IN T/NK CELLS HAS NOT YET BEEN CLARIFIED. IN THE PRIMARY INFECTION, EBV INFECTS B CELLS AND EPITHELIAL CELLS AND MAY ALSO INFECT SOME T/NK CELLS. IN SOME INDIVIDUALS, BECAUSE OF POOR PRESENTATION BY SPECIFIC HUMAN LEUKOCYTE ANTIGENS OR THE GENETIC BACKGROUND, EBV-INFECTED T/NK CELLS EVADE HOST IMMUNITY AND SURVIVE. OCCASIONALLY, WITH THE HELP OF VIRAL ONCOGENES, EBV-ASSOCIATED T/NK LYMPHOPROLIFERATIVE DISEASES, SUCH AS CAEBV, MAY DEVELOP. THE SUBSEQUENT ACCUMULATION OF GENETIC MUTATIONS AND/OR EPIGENETIC MODIFICATIONS IN DRIVER GENES, SUCH AS DDX3X AND TP53, MAY LEAD TO OVERT LYMPHOMA AND LEUKEMIA. ACTIVATION-INDUCED CYTIDINE DEAMINASE AND THE APOBEC3 FAMILY, DRIVEN BY EBV INFECTION, MAY INDUCE CHROMOSOMAL RECOMBINATION AND SOMATIC MUTATIONS. 2018 4 1040 43 CLINICAL AND GENETIC CHARACTERIZATION OF EPSTEIN-BARR VIRUS-ASSOCIATED T/NK-CELL LYMPHOPROLIFERATIVE DISEASES. BACKGROUND: EPSTEIN-BARR VIRUS (EBV)-ASSOCIATED T-/NATURAL KILLER (T/NK)-CELL LYMPHOPROLIFERATIVE DISEASES CLINICALLY TAKE ON VARIOUS FORMS, RANGING FROM AN INDOLENT COURSE TO AN AGGRESSIVE CONDITION. OBJECTIVE: CLINICALLY, FAILURE TO ESTABLISH PRECISE DIAGNOSIS AND PROVIDE PROPER TREATMENT MAKES IT DIFFICULT TO HELP PATIENTS. WE SOUGHT TO BETTER UNDERSTAND THE UNDERLYING PATHOGENESIS AND TO IDENTIFY GENETIC PROGNOSTIC FACTORS TO ACHIEVE BETTER TREATMENT EFFICACY. METHODS: IN THIS STUDY, 119 CASES OF EBV-ASSOCIATED LYMPHOPROLIFERATIVE DISEASES, INCLUDING EBV-ASSOCIATED HEMOPHAGOCYTIC LYMPHOHISTIOCYTOSIS (N = 46) AND CHRONIC ACTIVE EBV DISEASE OF T/NK CELL TYPE (N = 73), WERE RETROSPECTIVELY EXAMINED. RESULTS: ADULTS AGED >20 YEARS AT ONSET ACCOUNTED FOR 71.4% OF OUR COHORT. ABOUT 54.6% PATIENTS WITH UNFAVORABLE OVERALL SURVIVAL DEVELOPED HEMOPHAGOCYTIC LYMPHOHISTIOCYTOSIS AND HAD HIGHER PLASMA EBV LOAD. ALLOGENIC HEMATOPOIETIC STEM-CELL TRANSPLANTATION WAS THE SOLE INDEPENDENT FAVORABLE FACTOR. WE SYSTEMATICALLY SCREENED GERMLINE AND SOMATIC ABERRATIONS BY WHOLE-EXOME AND TARGETED SEQUENCING. AMONG 372 ANTIVIRAL IMMUNITY GENES, GERMLINE VARIANTS OF 8 GENES WERE SIGNIFICANTLY ENRICHED. FROM A PANEL OF 24 DRIVER GENES, SOMATIC MUTATIONS WERE FREQUENTLY IDENTIFIED IN DOMINANT EBV-INFECTED T/NK CELLS. PATIENTS CARRYING ANY GERMLINE/SOMATIC ABERRATIONS IN EPIGENETIC MODIFIERS AND RIG-I-LIKE RECEPTOR (RLR) PATHWAY HAD WORSE OVERALL SURVIVAL THAN THOSE WITHOUT 2 TYPE ABERRATIONS. IMPORTANTLY, PATIENTS WITH IFIH1 AND/OR DDX3X ABERRATIONS IN THE RLR PATHWAY HAD HIGHER PLASMA AND NK-CELL EBV LOAD. KNOCKDOWN OF DDX3X IN NKYS CELLS DOWNREGULATED RLR SIGNALING ACTIVITIES AND ELEVATED THE EXPRESSION OF EBV-ENCODED ONCOGENES SUCH AS LMP1 AND EBNA1. CONCLUSION: GENETIC DEFECTS WERE PREVALENT IN ADULT EBV-ASSOCIATED HEMOPHAGOCYTIC LYMPHOHISTIOCYTOSIS PATIENTS AND PATIENTS WITH CHRONIC ACTIVE EBV DISEASE OF T/NK CELL TYPE; THESE DEFECTS WERE ASSOCIATED WITH UNFAVORABLE PROGNOSIS. THESE FINDINGS CAN HELP CLINICIANS WORK OUT MORE PRECISE STAGING OF THE CONDITION AND PROVIDE NEW INSIGHTS INTO THESE EBV-ASSOCIATED DISEASES. 2023 5 5960 27 TELOMERE LENGTH IN HEPATOCELLULAR CARCINOMA AND PAIRED ADJACENT NON-TUMOR TISSUES BY QUANTITATIVE PCR. TELOMERE SHORTENING LIMITS THE PROLIFERATIVE CAPACITY OF HUMAN CELLS, RESTRAINS THE REGENERATIVE CAPACITY OF ORGAN SYSTEMS DURING CHRONIC DISEASES AND AGING AND ALSO INDUCES CHROMOSOMAL INSTABILITY AS WELL AS INITIATION OF CANCER. PREVIOUS STUDIES DEMONSTRATED THAT TELOMERES ARE OFTEN SIGNIFICANTLY SHORTER IN TUMOR TISSUE, INCLUDING HEPATOCELLULAR CARCINOMA (HCC), COMPARED TO THE SURROUNDING TISSUE, BUT TELOMERE LENGTH IN HCC TISSUES WAS NOT CORRELATED WITH SEVERAL CLINICAL PARAMETERS, SUCH AS AGE, SEX, HBV OR HCV INFECTIONS AND TUMOR SIZE. IN THE PRESENT STUDY, THE TELOMERE LENGTH RATIO OF 36 PAIRED HCC, AND THEIR ADJACENT NON-TUMOR TISSUES WAS MEASURED BY QUANTITATIVE PCR (Q-PCR). THE MEAN TELOMERE LENGTHS (SD) FOR HCC AND ADJACENT NON-TUMOR TISSUES WERE 0.26 (0.10) AND 0.47 (0.20) RESPECTIVELY (T = 6.22, P < 0.0001). THERE WAS A LARGE DIFFERENCE IN THE DISTRIBUTION OF SUBJECTS BASED ON TELOMERE LENGTH IN TUMOR AND ADJACENT NON-TUMOR TISSUES. THE NUMBER OF TUMORS WITH TELOMERE LENGTH SHORTER THAN 0.50 WAS MUCH HIGHER THAN THAT OF ADJACENT NON-TUMOR TISSUES; MORE THAN 90% OF THE TISSUES WITH TELOMERE LENGTH > OR = 0.50 WERE ADJACENT NON-TUMOR TISSUES. THE CORRELATIONS BETWEEN TELOMERE LENGTH AND AFLATOXIN B1- AND POLYCYCLIC AROMATIC HYDROCARBON-DNA ADDUCTS LEVEL, P53 MUTATIONS AND P16 HYPERMETHYLATION STATUS WERE ALSO TESTED, BUT NO SIGNIFICANT ASSOCIATIONS WERE FOUND. THE RELATIONSHIP BETWEEN TELOMERE LENGTH SHORTENING, CHEMICAL CARCINOGEN EXPOSURE, AND GENETIC AND EPIGENETIC CHANGES IN HEPATOCARCINOGENESIS NEEDS FURTHER INVESTIGATION. 2007 6 1501 13 DNA METHYLATION ANALYSIS OF HUMAN TISSUE-SPECIFIC CONNEXIN GENES. CONNEXINS ARE THE STRUCTURAL PROTEINS OF GAP JUNCTIONS AND THEIR FUNCTIONING AS TUMOR SUPPRESSORS IS WELL KNOWN. EPIGENETIC MODIFICATIONS, SUCH AS METHYLATION OF CONNEXIN GENES, PLAY IMPORTANT ROLES IN REGULATING GENE EXPRESSION. OVER THE PAST DECADE, SEVERAL METHODS HAVE BEEN APPLIED TO CHARACTERIZE DNA METHYLATION-SPECIFIC LOCI OF CONNEXIN GENES. THIS CHAPTER DESCRIBES ANALYSIS OF SELECTIVE CONNEXIN32 AND CONNEXIN43 GENE DNA METHYLATION IN HUMAN GASTRIC TISSUES USING METHYLATION-SPECIFIC PCR, BISULFITE-SPECIFIC PCR SEQUENCING AS WELL AS MASSARRAY TECHNIQUES. 2016 7 3745 26 INSIGHTS INTO THE DIVERSE EFFECTS OF NITRIC OXIDE ON TUMOR BIOLOGY. AMONG ITS MANY ROLES IN CELLULAR BIOLOGY, NITRIC OXIDE (.NO) HAS LONG BEEN ASSOCIATED WITH CANCERS BOTH AS A PROTUMORIGENIC AND AS AN ANTITUMORIGENIC AGENT. THE DUAL NATURE OF THIS SIGNALING MOLECULE IN VARIED SETTINGS IS ATTRIBUTABLE TO ITS TEMPORAL AND CONCENTRATION-DEPENDENT EFFECTS THAT PRODUCE DIFFERENT PHENOTYPES. THE STEADY-STATE .NO CONCENTRATION WITHIN THE CELL IS A BALANCE BETWEEN ITS RATE OF ENZYMATIC SYNTHESIS FROM THE THREE NITRIC OXIDE SYNTHASE (NOS) ISOFORMS AND CONSUMPTION VIA NUMEROUS METABOLIC PATHWAYS AND DEMONSTRATES STRONG DEPENDENCE ON THE TISSUE OXYGEN CONCENTRATION. NOS EXPRESSION AND .NO PRODUCTION ARE OFTEN DEREGULATED AND ASSOCIATED WITH NUMEROUS TYPES OF CANCERS WITH DISSIMILAR PROGNOSTIC OUTCOMES. .NO INFLUENCES SEVERAL FACETS OF TUMOR INITIATION AND PROGRESSION INCLUDING DNA DAMAGE, CHRONIC INFLAMMATION, ANGIOGENESIS, EPITHELIAL-MESENCHYMAL TRANSITION, AND METASTASIS, TO NAME A FEW. THE ROLE OF .NO AS AN EPIGENETIC MODULATOR HAS ALSO RECENTLY EMERGED AND HAS POTENTIALLY IMPORTANT MECHANISTIC IMPLICATIONS IN REGULATING TRANSCRIPTION OF ONCOGENES AND TUMOR-SUPPRESSOR GENES. .NO-DERIVED CELLULAR ADDUCTS SUCH AS DINITROSYLIRON COMPLEXES AND THE FORMATION OF HIGHER NITROGEN OXIDES FURTHER ALTER ITS CELLULAR BEHAVIOR. AMONG ANTICANCER STRATEGIES, THE USE OF NOS AS A PROGNOSTIC BIOMARKER AND MODULATION OF .NO PRODUCTION FOR THERAPEUTIC BENEFIT HAVE GAINED IMPORTANCE OVER THE PAST DECADE. NUMEROUS .NO-RELEASING DRUGS AND NOS INHIBITORS HAVE BEEN EVALUATED IN PRECLINICAL AND CLINICAL SETTINGS TO ARREST TUMOR GROWTH. TAKEN TOGETHER, .NO AFFECTS VARIOUS ARMS OF CANCER SIGNALING NETWORKS. AN OVERVIEW OF THIS COMPLEX INTERPLAY IS PROVIDED IN THIS CHAPTER. 2014 8 4227 22 METHYLATION OF FREE-FLOATING DEOXYRIBONUCLEIC ACID FRAGMENTS IN THE BRONCHOALVEOLAR LAVAGE FLUID OF DOGS WITH CHRONIC BRONCHITIS EXPOSED TO ENVIRONMENTAL TOBACCO SMOKE. BACKGROUND: THE ETIOLOGY OF CANINE CHRONIC BRONCHITIS (CB) IS NOT COMPLETELY UNDERSTOOD, ALTHOUGH EXPOSURE TO ENVIRONMENTAL TOBACCO SMOKE (ETS) AFFECTS THE AIRWAY INFLAMMATORY RESPONSES IN SOME DOGS WITH CB. THE MECHANISM BY WHICH THIS OCCURS IS UNKNOWN. FINDINGS: WE INVESTIGATED THE CONCENTRATIONS AND METHYLATION RATES OF FREE-FLOATING DNA FRAGMENTS IN BRONCHOALVEOLAR LAVAGE FLUID (BALF) FROM DOGS WITH CHRONIC BRONCHITIS. BASED ON SERUM COTININE LEVELS, DOGS WITH CB WERE DIVIDED INTO 2 GROUPS: DOGS THAT EITHER HAD OR HAD NOT BEEN EXPOSED TO ETS. OUR RESULTS DEMONSTRATED THAT THE TOTAL NUCLEATED CELL AND MACROPHAGE NUMBERS INCREASED IN BALF OF ETS-EXPOSED DOGS WITH CB. THERE WERE NO SIGNIFICANT DIFFERENCES IN DNA CONCENTRATIONS AND METHYLATION RATES IN BALF BETWEEN THE 2 GROUPS. HOWEVER, 3 OUT OF 8 DOGS EXPOSED TO ETS HAD HIGH DNA METHYLATION RATES IN THEIR BALF SAMPLES. CONCLUSION: OUR RESULTS SUGGEST THAT ETS EXPOSURE LEADS TO EPIGENETIC MODIFICATIONS OF CELLULAR COMPONENTS IN BALF IN DOGS DIAGNOSED WITH CB. 2015 9 2797 20 FCER1G GENE HYPOMETHYLATION IN PATIENTS WITH RHEUMATOID ARTHRITIS. RHEUMATOID ARTHRITIS (RA) IS A CHRONIC AUTOIMMUNE DISEASE THAT, WHEN IMPROPERLY TREATED, LEADS TO DISABILITY IN PATIENTS. VARIOUS FACTORS THAT MAY CAUSE THE DEVELOPMENT AND ACTIVITY OF RA ARE BEING CONSIDERED. EPIGENETIC FACTORS ARE ALSO RECEIVING INCREASING ATTENTION. IN OUR STUDY, WE ANALYZED THE ASSOCIATION BETWEEN FCER1G GENE METHYLATION AND RA ACTIVITY. WE CONDUCTED OUR STUDY IN 50 RA PATIENTS AND 24 CONTROLS. THE PATIENTS WERE DIVIDED INTO TWO GROUPS IN TERMS OF HIGH DISEASE ACTIVITY AND REMISSION. QUANTITATIVE REAL-TIME METHYLATION-SPECIFIC PCR WAS USED TO ANALYZE THE METHYLATION STATUS OF THE INVESTIGATED GENES. WE OBSERVED THAT RA PATIENTS HAVE LOWER LEVELS OF METHYLATION OF THE FCER1G GENE COMPARED TO CONTROLS, BUT WE DID NOT FIND ANY DIFFERENCE IN THE METHYLATION STATUS OF THIS GENE BETWEEN PATIENTS WITH HIGH DISEASE ACTIVITY AND REMISSION. THE RESULTS OF THIS STUDY SUGGEST THAT FCER1G GENE METHYLATION MAY BE A NEW POTENTIAL EPIGENETIC MARKER OF RA THAT IS INDEPENDENT OF DISEASE ACTIVITY. 2022 10 5127 27 POSTMENOPAUSAL UTERINE LEIOMYOMAS AND CHRONIC LYMPHADENOPATHY: EXPLORING EPIGENETIC CHANGES AND PATHOPHYSIOLOGY. UTERINE LEIOMYOMAS (LM) ARE TUMORS ARISING FROM THE NON-NEOPLASTIC PROLIFERATION OF SMOOTH MUSCLE CELLS WITHIN THE MYOMETRIUM. LIKE BENIGN TUMORS, LM ARE NOT GENERALLY SPREAD THROUGH THE LYMPHATIC SYSTEM, AND THEREFORE SHOULD NOT BE ASSOCIATED WITH LYMPHADENOPATHY. HEREIN, WE PRESENT A CASE OF A 60-YEAR-OLD FEMALE WHO PRESENTED TO THE CLINIC WITH POSTMENOPAUSAL BLEEDING IN THE SETTING OF SONOGRAPHICALLY EVIDENT UTERINE LM AND ABDOMINAL LYMPHADENOPATHY. A LYMPH NODE BIOPSY REVEALED PLASMA CELLS AND AN EOSINOPHILIC MATERIAL PRESUMPTIVELY DIAGNOSED AS AMYLOID. SHE THEN UNDERWENT AN ABDOMINAL HYSTERECTOMY FOR DEFINITIVE TREATMENT OF LM. SURGICAL PATHOLOGY CONFIRMED THE CLINICAL DIAGNOSIS OF UTERINE AND CERVICAL LEIOMYOMA. CURRENT LITERATURE SUGGESTS THAT GENETIC AND EPIGENETIC ABNORMALITIES CONTRIBUTE TO THE PATHOGENESIS OF LM IN ADDITION TO HORMONAL SIGNALS SUCH AS ESTROGEN AND PROGESTERONE. IT IS UNUSUAL FOR LM TO OCCUR IN POST-MENOPAUSAL WOMEN DUE TO REDUCED HORMONAL INFLUENCE. THEREFORE, THIS CASE EXPLORED AN ALTERNATIVE MECHANISM OF TUMOR PROLIFERATION. THIS CASE HYPOTHESIZES THAT GENETIC MUTATIONS AND EPIGENETIC CHANGES RESULTING FROM CHRONIC INFLAMMATORY OFFENSES CONTRIBUTED TO LM GROWTH AND LYMPHADENOPATHY. 2021 11 2031 19 EPIGENETIC CHANGES IN LYMPHOCYTES OF SOLVENT-EXPOSED INDIVIDUALS. AIM: WE INVESTIGATED GLOBAL DNA METHYLATION ALTERATIONS IN LYMPHOCYTES OF SOLVENT WORKERS AND CHRONIC TOXIC ENCEPHALOPATHY (CTE) PATIENTS AND EXPLORED POTENTIAL GENE-ENVIRONMENT INTERACTIONS FOR GST. POPULATION & METHODS: A CROSS-SECTIONAL STUDY WAS SET UP IN 41 REFERENTS, 128 SOLVENT WORKERS AND 23 CTE PATIENTS. RESULTS: WE FOUND A GLOBAL DNA HYPERMETHYLATION IN THE SOLVENT-EXPOSED POPULATION COMPARED WITH THE REFERENTS (P = 0.001, R = -0.544). GLOBAL DNA METHYLATION WAS NEGATIVELY ASSOCIATED WITH EXPOSURE. FURTHERMORE, GSTP1 GENOTYPIC POLYMORPHISM WAS FOUND TO BE SIGNIFICANTLY ASSOCIATED (P = 0.033) WITH GLOBAL DNA HYPOMETHYLATION, WHICH INDICATES A POTENTIAL ROLE FOR GENE-ENVIRONMENT INTERACTION IN THE ETIOLOGY OF SOLVENT-INDUCED NEUROBEHAVIORAL DISORDERS. CONCLUSION: THIS STUDY INDICATES THAT SOLVENT-INDUCED DNA METHYLATION ALTERATIONS HAVE AN IMPACT ON NEUROTOXICITY AND DEVELOPMENT OF CTE. 2012 12 2762 26 EXPRESSION OF TET2 ENZYME INDICATES ENHANCED EPIGENETIC MODIFICATION OF CELLS IN PERIODONTITIS. DNA METHYLATION IS AN IMPORTANT EPIGENETIC MECHANISM INVOLVED IN THE REGULATION OF GENE EXPRESSION, AND A REDUCTION IN DNA METHYLATION INFLUENCES CELL-CYCLE PROGRESSION AND CELL DIFFERENTIATION IN INFLAMMATORY CELLS. THE AIM OF THE PRESENT STUDY WAS TO ANALYZE THE DNA-METHYLATION PATTERN AT LOCAL AND GLOBAL/SYSTEMIC LEVELS IN PATIENTS WITH PERIODONTITIS AND GINGIVITIS. TWENTY-ONE SUBJECTS WITH GENERALIZED, SEVERE PERIODONTITIS AND 17 SUBJECTS WITH GINGIVAL INFLAMMATION BUT NO ATTACHMENT LOSS WERE RECRUITED. GINGIVAL BIOPSIES AND PERIPHERAL BLOOD SAMPLES WERE COLLECTED AND PREPARED FOR IMMUNOHISTOCHEMICAL ANALYSIS OF 5-METHYLCYTOSINE (5MC), 5-HYDROXYMETHYLCYTOSINE (5HMC), TEN-ELEVEN TRANSLOCATION 2 (TET2), AND DNA METHYLTRANSFERASE 1 (DNMT1). WHILST A SIMILAR PATTERN FOR 5MC AND 5HMC DNA METHYLATION WAS FOUND IN BOTH TYPES OF LESIONS, A SIGNIFICANTLY LARGER PROPORTION OF TET2-POSITIVE CELLS WAS FOUND IN PERIODONTITIS LESIONS THAN IN GINGIVITIS LESIONS. QUANTITATIVE REAL-TIME PCR ANALYSIS SHOWED NO DIFFERENCES BETWEEN GINGIVITIS AND PERIODONTITIS LESIONS REGARDING EXPRESSION OF TET2 AND ISOCITRATE DEHYDROGENASE (IDH) GENES, WHILE THE GLOBAL LEVEL OF 5HMC WAS SIGNIFICANTLY HIGHER IN BLOOD THAN IN TISSUE IN PATIENTS WITH PERIODONTITIS. IT IS SUGGESTED THAT EPIGENETIC CHANGES ARE MORE COMMON IN PERIODONTITIS LESIONS THAN IN GINGIVITIS LESIONS AND THAT SUCH CHANGES ARE TISSUE SPECIFIC. 2016 13 846 31 CHILDHOOD EXPOSURE TO AMBIENT POLYCYCLIC AROMATIC HYDROCARBONS IS LINKED TO EPIGENETIC MODIFICATIONS AND IMPAIRED SYSTEMIC IMMUNITY IN T CELLS. BACKGROUND: EVIDENCE SUGGESTS THAT EXPOSURE TO POLYCYCLIC AROMATIC HYDROCARBONS (PAHS) INCREASES ATOPY; IT IS UNCLEAR HOW PAH EXPOSURE IS LINKED TO INCREASED SEVERITY OF ATOPIC DISEASES. OBJECTIVE: WE HYPOTHESIZED THAT AMBIENT PAH EXPOSURE IS LINKED TO IMPAIRMENT OF IMMUNITY IN ATOPIC CHILDREN (DEFINED AS CHILDREN WITH ASTHMA AND/OR ALLERGIC RHINITIS) FROM FRESNO, CALIFORNIA, AN AREA WITH ELEVATED AMBIENT PAHS. METHODS: WE RECRUITED 256 SUBJECTS FROM FRESNO, CA. AMBIENT PAH CONCENTRATIONS (NG/M(3) ) WERE MEASURED USING A SPATIAL-TEMPORAL REGRESSION MODEL OVER MULTIPLE TIME PERIODS. ASTHMA DIAGNOSIS WAS DETERMINED BY CURRENT NHLBI CRITERIA. PHENOTYPING AND FUNCTIONAL IMMUNE MEASUREMENTS WERE PERFORMED FROM ISOLATED CELLS. FOR EPIGENETIC MEASUREMENTS, DNA WAS ISOLATED AND PYROSEQUENCED. RESULTS: WE SHOW THAT HIGHER AVERAGE PAH EXPOSURE WAS SIGNIFICANTLY ASSOCIATED WITH IMPAIRED TREG FUNCTION AND INCREASED METHYLATION IN THE FORKHEAD BOX PROTEIN 3 (FOXP3) LOCUS (P < 0.05), CONDITIONAL ON ATOPIC STATUS. THESE EPIGENETIC MODIFICATIONS WERE SIGNIFICANTLY LINKED TO DIFFERENTIAL PROTEIN EXPRESSION OF FOXP3 (P < 0.001). METHYLATION WAS ASSOCIATED WITH CELLULAR FUNCTIONAL CHANGES, SPECIFICALLY TREG DYSFUNCTION, AND AN INCREASE IN TOTAL PLASMA IGE LEVELS. PROTEIN EXPRESSION OF IL-10 DECREASED AND IFN-GAMMA INCREASED AS THE EXTENT OF PAH EXPOSURE INCREASED. THE STRENGTH OF THE ASSOCIATIONS GENERALLY INCREASED AS THE TIME WINDOW FOR AVERAGE PAH EXPOSURE INCREASED FROM 24 HR TO 1 YEAR, SUGGESTING MORE OF A CHRONIC RESPONSE. SIGNIFICANT ASSOCIATIONS WITH CHRONIC PAH EXPOSURE AND IMMUNE OUTCOMES WERE ALSO OBSERVED IN SUBJECTS WITH ALLERGIC RHINITIS. CONCLUSIONS AND CLINICAL RELEVANCE: COLLECTIVELY, THESE RESULTS DEMONSTRATE THAT INCREASED AMBIENT PAH EXPOSURE IS ASSOCIATED WITH IMPAIRED SYSTEMIC IMMUNITY AND EPIGENETIC MODIFICATIONS IN A KEY LOCUS INVOLVED IN ATOPY: FOXP3, WITH A HIGHER IMPACT ON ATOPIC CHILDREN. THE RESULTS SUGGEST THAT INCREASED ATOPIC CLINICAL SYMPTOMS IN CHILDREN COULD BE LINKED TO INCREASED PAH EXPOSURE IN AIR POLLUTION. 2015 14 143 21 ABERRANT DNA METHYLATION OF TWO TUMOR SUPPRESSOR GENES, P14(ARF) AND P15(INK4B), AFTER CHRONIC OCCUPATIONAL EXPOSURE TO LOW LEVEL OF BENZENE. BACKGROUND: EXPOSURE TO BENZENE WOULD BE ASSOCIATED WITH MANY DISEASES INCLUDING LEUKEMIA. EPIGENETIC ALTERATIONS SEEM TO BE AMONG THE MAIN MECHANISMS INVOLVED. OBJECTIVE: TO DETERMINE IF CHRONIC OCCUPATIONAL EXPOSURE TO LOW LEVEL OF BENZENE WOULD BE ASSOCIATED WITH DNA METHYLATION. METHODS: GLOBAL DNA METHYLATION AND PROMOTER-SPECIFIC METHYLATION OF THE TWO TUMOR SUPPRESSOR GENES, P14(ARF) AND P15(INK4B), WERE ASSESSED EMPLOYING METHYLATION-SPECIFIC PCR USING THE DNA EXTRACTED FROM 40 PETROCHEMICAL WORKERS EXPOSED TO AMBIENT BENZENE LEVELS OF <1 PPM, AND 31 OFFICE WORKERS NOT EXPOSED TO BENZENE OR ITS DERIVATIVES. RESULTS: WHILE AN INCREASE IN GLOBAL DNA METHYLATION OF 5% IN P14(ARF) (P=0.501) AND 28% IN P15(INK4B) (P=0.02) GENES WAS OBSERVED IN THE EXPOSED GROUP, NO HYPERMETHYLATION IN EITHER OF THE STUDIED GENES WAS OBSERVED IN THE UNEXPOSED GROUP. NO SIGNIFICANT ASSOCIATION WAS FOUND BETWEEN THE FREQUENCY OF ABERRANT METHYLATION AND EITHER OF AGE, WORK EXPERIENCE, AND SMOKING HABIT IN THE EXPOSED GROUP. CONCLUSION: CHRONIC OCCUPATIONAL EXPOSURE TO LOWER THAN THE PERMISSIBLE EXPOSURE LIMIT OF BENZENE MAY STILL RESULT IN DNA METHYLATION OF TUMOR SUPPRESSOR GENES THAT MAY ULTIMATELY LEAD TO DEVELOPMENT OF CANCER. 2018 15 2684 29 EVALUATION OF X CHROMOSOME INACTIVATION WITH RESPECT TO HLA GENETIC SUSCEPTIBILITY IN RHEUMATOID ARTHRITIS AND SYSTEMIC SCLEROSIS. BACKGROUND: AUTOIMMUNE DISEASES, INCLUDING RHEUMATOID ARTHRITIS (RA) AND SYSTEMIC SCLEROSIS (SSC) ARE CHARACTERIZED BY A STRONG GENETIC SUSCEPTIBILITY FROM THE HUMAN LEUCOCYTE ANTIGEN (HLA) LOCUS. ADDITIONALLY, DISORDERS OF EPIGENETIC PROCESSES, IN PARTICULAR NON-RANDOM X CHROMOSOME INACTIVATION (XCI), HAVE BEEN REPORTED IN MANY FEMALE-PREDOMINANT AUTOIMMUNE DISEASES. HERE WE TEST THE HYPOTHESIS THAT WOMEN WITH RA OR SSC WHO ARE STRONGLY GENETICALLY PREDISPOSED ARE LESS SUSCEPTIBLE TO XCI BIAS. METHODS: USING METHYLATION SENSITIVE GENOTYPING OF THE ANDROGEN RECEPTOR (AR) GENE, XCI PROFILES WERE PERFORMED IN PERIPHERAL BLOOD MONONUCLEAR CELLS FROM 161 WOMEN WITH RA, 96 WOMEN WITH SSC AND 100 HEALTHY WOMEN. HLA-DRB1 AND DQB1 WERE GENOTYPED. PRESENCE OF SPECIFIC AUTOANTIBODIES WAS DOCUMENTED FOR PATIENTS. XCI SKEWING WAS DEFINED AS HAVING A RATIO >/= 80:20 OF CELLS INACTIVATING THE SAME X CHROMOSOME. RESULTS: 110 WOMEN WITH RA, 68 WOMEN WITH SSC, AND 69 CONTROLS WERE INFORMATIVE FOR THE AR POLYMORPHISM. AMONG THEM 40.9% OF RA PATIENTS AND 36.8% OF SSC PATIENTS HAD SKEWED XCI COMPARED TO 17.4% OF HEALTHY WOMEN (P = 0.002 AND 0.018, RESPECTIVELY). PRESENCE OF RA-SUSCEPTIBILITY ALLELES CODING FOR THE "SHARED EPITOPE" CORRELATED WITH HIGHER SKEWING AMONG RA PATIENTS (P = 0.002) AND SUCH CORRELATION WAS NOT OBSERVED IN OTHER WOMEN, HEALTHY OR WITH SSC. PRESENCE OF SSC-SUSCEPTIBILITY ALLELES DID NOT CORRELATE WITH XCI PATTERNS AMONG SSC PATIENTS. CONCLUSION: DATA DEMONSTRATE XCI SKEWING IN BOTH RA AND SSC COMPARED TO HEALTHY WOMEN. UNEXPECTEDLY, SKEWED XCI OCCURS MORE OFTEN IN WOMEN WITH RA CARRYING THE SHARED EPITOPE, WHICH USUALLY REFLECTS SEVERE DISEASE. THIS REINFORCES THE VIEW THAT LOSS OF MOSAICISM IN PERIPHERAL BLOOD MAY BE A CONSEQUENCE OF CHRONIC AUTOIMMUNITY. 2016 16 6078 26 THE EFFECT OF CHRONIC ARSENIC EXPOSURE IN ZEBRAFISH. ARSENIC IS A PREVALENT ENVIRONMENTAL TOXIN AND A GROUP ONE HUMAN CARCINOGENIC AGENT. CHRONIC ARSENIC EXPOSURE HAS BEEN ASSOCIATED WITH MANY HUMAN DISEASES. THE AIM OF THIS STUDY IS TO EVALUATE ZEBRAFISH AS AN ANIMAL MODEL TO ASSESS ARSENIC TOXICITY IN ELEVATED LONG-TERM ARSENIC EXPOSURE. WITH PROLONGED EXPOSURE (6 MONTHS) TO VARIOUS CONCENTRATIONS OF ARSENIC FROM 50 PPB TO 300 PPB, EFFECTS OF ARSENIC ACCUMULATION IN ZEBRAFISH TISSUES, AND PHENOTYPES WERE INVESTIGATED. RESULTS SHOWED THAT THERE ARE NO SIGNIFICANT CHANGES OF ARSENIC RETENTION IN ZEBRAFISH TISSUES, AND ZEBRAFISH DID NOT EXHIBIT ANY VISIBLE TUMOR FORMATION UNDER ARSENIC EXPOSURE CONDITIONS. HOWEVER, THE ZEBRAFISH DEMONSTRATE A DYSFUNCTION IN THEIR NEUROLOGICAL SYSTEM, WHICH IS REFLECTED BY A REDUCTION OF LOCOMOTIVE ACTIVITY. MOREOVER, ELEVATED LEVELS OF THE SUPEROXIDE DISMUTASE (SOD2) PROTEIN WERE DETECTED IN THE EYE AND LIVER, SUGGESTING INCREASED OXIDATIVE STRESS. IN ADDITION, THE PROGENIES OF ARSENIC-TREATED PARENTS DISPLAYED A SMALLER BIOMASS (FOUR-FOLD REDUCTION IN BODY WEIGHT) COMPARED WITH THOSE FROM THEIR PARENTAL CONTROLS. THIS RESULT INDICATES THAT ARSENIC MAY INDUCE GENETIC OR EPIGENETIC CHANGES THAT ARE THEN PASSED ON TO THE NEXT GENERATION. OVERALL, THIS STUDY DEMONSTRATES THAT ZEBRAFISH IS A CONVENIENT VERTEBRATE MODEL WITH ADVANTAGES IN THE EVALUATION OF ARSENIC-ASSOCIATED NEUROLOGICAL DISORDERS AS WELL AS ITS INFLUENCES ON THE OFFSPRING. 2016 17 5057 20 PHENOBARBITAL MECHANISTIC DATA AND RISK ASSESSMENT: ENZYME INDUCTION, ENHANCED CELL PROLIFERATION, AND TUMOR PROMOTION. CHRONIC EXPOSURE TO HIGH DOSES OF PHENOBARBITAL (PB) CAUSES HEPATOCELLULAR ADENOMAS IN BOTH MICE AND RATS AND HEPATOCELLULAR CARCINOMAS IN SOME STRAINS OF MICE. LONG-TERM PB THERAPY HAS NOT BEEN FOUND TO CAUSE HUMAN TUMORS. PB IS NOT DNA REACTIVE, AND MOST GENOTOXICITY TESTS HAVE YIELDED NEGATIVE RESULTS. PB HAS BEEN EXTENSIVELY STUDIED AS AN EPIGENETIC, RODENT LIVER TUMOR PROMOTER. AT EXPOSURES CAUSING RODENT LIVER TUMORS, PB HAS MEASURABLE EFFECTS ON HEPATOCYTES: PB INHIBITS CELL-TO-CELL COMMUNICATION; PB INDUCES ENZYMES, INCLUDING P450 CYTOCHROMES; PB STIMULATES PROLIFERATION AND INHIBITS APOPTOSIS OF HEPATOCYTES IN NEOPLASTIC FOCI. THRESHOLD EXPOSURES FOR SOME OF THESE ENDPOINTS COINCIDE WITH THE THRESHOLD EXPOSURE FOR TUMORIGENESIS. 1996 18 2766 30 EXPRESSION, POLYMORPHISM AND METHYLATION PATTERN OF INTERLEUKIN-6 IN PERIODONTAL TISSUES. PERIODONTITIS IS CONSIDERED AN INFLAMMATORY DISORDER OF BACTERIAL ETIOLOGY THAT RESULTS IN PERIODONTAL TISSUE DESTRUCTION, AS A RESULT OF COMPLEX INTERACTIONS BETWEEN PERIODONTAL PATHOGENS, HOST AND IMMUNE RESPONSE. GENETIC AND EPIGENETIC MECHANISMS MAY MODULATE THE INDIVIDUAL RESPONSE SINCE IT IS ABLE TO INFLUENCE THE GENE EXPRESSION. THE AIM OF THIS STUDY WAS TO EVALUATE THE IMPACT OF -174 G/C POLYMORPHISM AND THE METHYLATION STATUS OF THE PROMOTER REGION OF IL-6 GENE ON THE EXPRESSION OF IL-6 IN GINGIVAL SAMPLES FROM INDIVIDUALS WITH CHRONIC PERIODONTITIS. GINGIVAL BIOPSIES WERE COLLECTED FROM 21 PATIENTS WITH CHRONIC PERIODONTITIS AND 21 CONTROLS. HISTOLOGIC SECTIONS STAINED BY HEMATOXYLIN-EOSIN WERE USED FOR HISTOPATHOLOGICAL EVALUATION. THE IL-6 GENE EXPRESSION WAS ASSESSED BY QUANTITATIVE REAL-TIME PCR. THE POLYMORPHISM IL-6 -174 C/G WAS STUDIED BY POLYMERASE CHAIN REACTION (PCR) AMPLIFICATION AND RESTRICTION ENDONUCLEASE DIGESTION (HSPII). METHYLATION-SPECIFIC POLYMERASE CHAIN REACTION WAS USED TO VERIFY THE DNA METHYLATION PATTERN. THE NUMBER OF INFLAMMATORY CELLS IN TISSUE FRAGMENTS FROM INDIVIDUALS WITH CHRONIC PERIODONTITIS WAS HIGHER THAN IN THE CONTROL GROUP AND THE INFLAMMATORY INFILTRATE WAS PREDOMINANTLY MONONUCLEAR. THE EXPRESSION OF IL-6 WAS HIGHER IN THE GROUP WITH PERIODONTITIS. IN POLYMORPHISM ASSAY, NO STATISTICAL DIFFERENCE IN THE DISTRIBUTION OF GENOTYPES AND ALLELES IN BOTH GROUPS WERE OBSERVED. THE MOST OF SAMPLES WERE PARTIALLY METHYLATED. NO DIFFERENCE WAS OBSERVED IN METHYLATION PATTERN FROM TWO DIFFERENT REGIONS OF THE IL-6 GENE AMONG GROUPS. THE HIGH EXPRESSION OF IL-6 IS AN IMPORTANT FACTOR RELATED TO CHRONIC PERIODONTITIS, BUT WAS NOT ASSOCIATED WITH METHYLATION STATUS OR THE -174 (G/C) GENETIC POLYMORPHISM, SUGGESTING THAT OTHER MECHANISMS ARE INVOLVED IN THIS GENE TRANSCRIPTION REGULATION. 2013 19 1588 38 DNA METHYLATION PROFILING IMPLICATES EXPOSURE TO PCBS IN THE PATHOGENESIS OF B-CELL CHRONIC LYMPHOCYTIC LEUKEMIA. OBJECTIVES: TO CHARACTERIZE THE IMPACT OF PCB EXPOSURE ON DNA METHYLATION IN PERIPHERAL BLOOD LEUCOCYTES AND TO EVALUATE THE CORRESPONDING CHANGES IN RELATION TO POSSIBLE HEALTH EFFECTS, WITH A FOCUS ON B-CELL LYMPHOMA. METHODS: WE CONDUCTED AN EPIGENOME-WIDE ASSOCIATION STUDY ON 611 ADULTS FREE OF DIAGNOSED DISEASE, LIVING IN ITALY AND SWEDEN, IN WHOM WE ALSO MEASURED PLASMA CONCENTRATIONS OF 6 PCB CONGENERS, DDE AND HEXACHLOROBENZENE. RESULTS: WE IDENTIFIED 650 CPG SITES WHOSE METHYLATION CORRELATES STRONGLY (FDR < 0.01) WITH PLASMA CONCENTRATIONS OF AT LEAST ONE PCB CONGENER. STRONGER EFFECTS WERE OBSERVED IN MALES AND IN SWEDEN. THIS EPIGENETIC EXPOSURE PROFILE SHOWS EXTENSIVE AND HIGHLY STATISTICALLY SIGNIFICANT OVERLAPS WITH PUBLISHED PROFILES ASSOCIATED WITH THE RISK OF FUTURE B-CELL CHRONIC LYMPHOCYTIC LEUKEMIA (CLL) AS WELL AS WITH CLINICAL CLL (38 AND 28 CPG SITES, RESPECTIVELY). FOR ALL THESE SITES, THE METHYLATION CHANGES WERE IN THE SAME DIRECTION FOR INCREASING EXPOSURE AND FOR HIGHER DISEASE RISK OR CLINICAL DISEASE STATUS, SUGGESTING AN ETIOLOGICAL LINK BETWEEN EXPOSURE AND CLL. MEDIATION ANALYSIS REINFORCED THE SUGGESTION OF A CAUSAL LINK BETWEEN EXPOSURE, CHANGES IN DNA METHYLATION AND DISEASE. DISEASE CONNECTIVITY ANALYSIS IDENTIFIED MULTIPLE ADDITIONAL DISEASES ASSOCIATED WITH DIFFERENTIALLY METHYLATED GENES, INCLUDING MELANOMA FOR WHICH AN ETIOLOGICAL LINK WITH PCB EXPOSURE IS ESTABLISHED, AS WELL AS DEVELOPMENTAL AND NEUROLOGICAL DISEASES FOR WHICH THERE IS CORRESPONDING EPIDEMIOLOGICAL EVIDENCE. DIFFERENTIALLY METHYLATED GENES INCLUDE MANY HOMEOBOX GENES, SUGGESTING THAT PCBS TARGET STEM CELLS. FURTHERMORE, NUMEROUS POLYCOMB PROTEIN TARGET GENES WERE HYPERMETHYLATED WITH INCREASING EXPOSURE, AN EFFECT KNOWN TO CONSTITUTE AN EARLY MARKER OF CARCINOGENESIS. CONCLUSIONS: THIS STUDY PROVIDES MECHANISTIC EVIDENCE IN SUPPORT OF A LINK BETWEEN EXPOSURE TO PCBS AND THE ETIOLOGY OF CLL AND UNDERLINES THE UTILITY OF OMIC PROFILING IN THE EVALUATION OF THE POTENTIAL TOXICITY OF ENVIRONMENTAL CHEMICALS. 2019 20 2662 32 EPSTEIN-BARR VIRUS AND MULTIPLE SCLEROSIS: A CONVOLUTED INTERACTION AND THE OPPORTUNITY TO UNRAVEL PREDICTIVE BIOMARKERS. SINCE THE EARLY 1980S, EPSTEIN-BARR VIRUS (EBV) INFECTION HAS BEEN DESCRIBED AS ONE OF THE MAIN RISK FACTORS FOR DEVELOPING MULTIPLE SCLEROSIS (MS), AND RECENTLY, NEW EPIDEMIOLOGICAL EVIDENCE HAS REINFORCED THIS PREMISE. EBV SEROCONVERSION PRECEDES ALMOST 99% OF THE NEW CASES OF MS AND LIKELY PREDATES THE FIRST CLINICAL SYMPTOMS. THE MOLECULAR MECHANISMS OF THIS ASSOCIATION ARE COMPLEX AND MAY INVOLVE DIFFERENT IMMUNOLOGICAL ROUTES, PERHAPS ALL RUNNING IN PARALLEL (I.E., MOLECULAR MIMICRY, THE BYSTANDER DAMAGE THEORY, ABNORMAL CYTOKINE NETWORKS, AND COINFECTION OF EBV WITH RETROVIRUSES, AMONG OTHERS). HOWEVER, DESPITE THE LARGE AMOUNT OF EVIDENCE AVAILABLE ON THESE TOPICS, THE ULTIMATE ROLE OF EBV IN THE PATHOGENESIS OF MS IS NOT FULLY UNDERSTOOD. FOR INSTANCE, IT IS UNCLEAR WHY AFTER EBV INFECTION SOME INDIVIDUALS DEVELOP MS WHILE OTHERS EVOLVE TO LYMPHOPROLIFERATIVE DISORDERS OR SYSTEMIC AUTOIMMUNE DISEASES. IN THIS REGARD, RECENT STUDIES SUGGEST THAT THE VIRUS MAY EXERT EPIGENETIC CONTROL OVER MS SUSCEPTIBILITY GENES BY MEANS OF SPECIFIC VIRULENCE FACTORS. SUCH GENETIC MANIPULATION HAS BEEN DESCRIBED IN VIRALLY-INFECTED MEMORY B CELLS FROM PATIENTS WITH MS AND ARE THOUGHT TO BE THE MAIN SOURCE OF AUTOREACTIVE IMMUNE RESPONSES. YET, THE ROLE OF EBV INFECTION IN THE NATURAL HISTORY OF MS AND IN THE INITIATION OF NEURODEGENERATION IS EVEN LESS CLEAR. IN THIS NARRATIVE REVIEW, WE WILL DISCUSS THE AVAILABLE EVIDENCE ON THESE TOPICS AND THE POSSIBILITY OF HARNESSING SUCH IMMUNOLOGICAL ALTERATIONS TO UNCOVER PREDICTIVE BIOMARKERS FOR THE ONSET OF MS AND PERHAPS FACILITATE PROGNOSTICATION OF THE CLINICAL COURSE. 2023