1 6111 83 THE EPIGENETIC ARCHITECTURE AT GENE PROMOTERS DETERMINES CELL TYPE-SPECIFIC LPS TOLERANCE. SYNOVIAL FIBROBLASTS (SF) DRIVE INFLAMMATION AND JOINT DESTRUCTION IN CHRONIC ARTHRITIS. HERE WE SHOW THAT SF POSSESS A DISTINCT TYPE OF LPS TOLERANCE COMPARED TO MACROPHAGES AND OTHER TYPES OF FIBROBLASTS. IN SF AND DERMAL FIBROBLASTS, GENES THAT WERE NON-TOLERIZABLE AFTER REPEATED LPS STIMULATION INCLUDED PRO-INFLAMMATORY CYTOKINES, CHEMOKINES AND MATRIX METALLOPROTEINASES, WHEREAS ANTI-VIRAL GENES WERE TOLERIZABLE. IN MACROPHAGES, ALL MEASURED GENES WERE TOLERIZABLE, WHEREAS IN GINGIVAL AND FORESKIN FIBROBLASTS THESE GENES WERE NON-TOLERIZABLE. REPEATED STIMULATION OF SF WITH LPS RESULTED IN LOSS OF ACTIVATING HISTONE MARKS ONLY IN PROMOTERS OF TOLERIZABLE GENES. THE EPIGENETIC LANDSCAPE AT PROMOTERS OF TOLERIZABLE GENES WAS SIMILAR IN UNSTIMULATED SF AND MONOCYTES, WHEREAS THE BASAL CONFIGURATION OF HISTONE MARKS PROFOUNDLY DIFFERED IN GENES THAT WERE NON-TOLERIZABLE IN SF ONLY. OUR DATA SUGGEST THAT THE EPIGENETIC CONFIGURATION AT GENE PROMOTERS REGULATES CELL-SPECIFIC LPS-INDUCED RESPONSES AND PRIMES SF TO SUSTAIN THEIR INFLAMMATORY RESPONSE IN CHRONIC ARTHRITIS. 2017 2 911 27 CHRONIC EXPOSURE TO TNF REPROGRAMS CELL SIGNALING PATHWAYS IN FIBROBLAST-LIKE SYNOVIOCYTES BY ESTABLISHING LONG-TERM INFLAMMATORY MEMORY. FIBROBLAST-LIKE SYNOVIOCYTES (FLS) PLAY A CRITICAL ROLE IN THE PATHOGENESIS OF RHEUMATOID ARTHRITIS (RA). CHRONIC INFLAMMATION INDUCES TRANSCRIPTOMIC AND EPIGENETIC MODIFICATIONS THAT IMPARTS A PERSISTENT CATABOLIC PHENOTYPE TO THE FLS, DESPITE THEIR DISSOCIATION FROM THE INFLAMMATORY ENVIRONMENT. WE ANALYZED HIGH THROUGHPUT GENE EXPRESSION AND CHROMATIN ACCESSIBILITY DATA FROM HUMAN AND MOUSE FLS FROM OUR AND OTHER STUDIES AVAILABLE ON PUBLIC REPOSITORIES, WITH THE GOAL OF IDENTIFYING THE PERSISTENTLY REPROGRAMMED SIGNALING PATHWAYS DRIVEN BY CHRONIC INFLAMMATION. WE FOUND THAT THE GENE EXPRESSION CHANGES INDUCED BY SHORT-TERM TUMOR NECROSIS FACTOR-ALPHA (TNF) TREATMENT WERE LARGELY SUSTAINED IN THE FLS EXPOSED TO CHRONIC INFLAMMATION. THESE CHANGES THAT INCLUDED BOTH ACTIVATION AND REPRESSION OF GENE EXPRESSION, WERE ACCOMPANIED BY THE REMODELING OF CHROMATIN ACCESSIBILITY. THE SUSTAINED ACTIVATED GENES (SAGS) INCLUDED ESTABLISHED PRO-INFLAMMATORY SIGNALING COMPONENTS KNOWN TO ACT AT MULTIPLE LEVELS OF NF-KAPPAB, STAT AND AP-1 SIGNALING CASCADES. INTERESTINGLY, THE SUSTAINED REPRESSED GENES (SRGS) INCLUDED CRITICAL MEDIATORS AND TARGETS OF THE BMP SIGNALING PATHWAY. WE THUS IDENTIFIED SUSTAINED REPRESSION OF BMP SIGNALING AS A UNIQUE CONSTITUENT OF THE LONG-TERM INFLAMMATORY MEMORY INDUCED BY CHRONIC INFLAMMATION. WE POSTULATE THAT SIMULTANEOUS TARGETING OF THESE ACTIVATED AND REPRESSED SIGNALING PATHWAYS MAY BE NECESSARY TO COMBAT RA PERSISTENCE. 2020 3 2748 29 EXPRESSION AND FUNCTION OF EZH2 IN SYNOVIAL FIBROBLASTS: EPIGENETIC REPRESSION OF THE WNT INHIBITOR SFRP1 IN RHEUMATOID ARTHRITIS. OBJECTIVES: TO STUDY THE EXPRESSION, REGULATION AND FUNCTION OF THE HISTONE METHYLTRANSFERASE ENHANCER OF ZESTE HOMOLOGUE 2 (EZH2) IN SYNOVIAL FIBROBLASTS (SF) FROM PATIENTS WITH RHEUMATOID ARTHRITIS (RA) AND OSTEOARTHRITIS (OA). METHODS: SF WERE OBTAINED FROM RA AND OA PATIENTS UNDERGOING JOINT SURGERY. EXPRESSION LEVELS WERE ASSESSED BY QUANTITATIVE REAL-TIME PCR AND WESTERN BLOT. KINASE INHIBITORS AND REPORTER GENE ASSAYS WERE EMPLOYED TO STUDY SIGNALLING PATHWAYS. FUNCTIONAL ANALYSES INCLUDED EZH2 OVEREXPRESSION BY PLASMID TRANSFECTION AND GENE SILENCING BY SMALL INTERFERING RNA. CHROMATIN IMMUNOPRECIPITATION ASSAY WAS USED TO ANALYSE HISTONE METHYLATION WITHIN DISTINCT PROMOTER REGIONS. RESULTS: BY STUDYING THE EXPRESSION AND FUNCTION OF EZH2 IN SF THE AUTHORS FOUND THAT EZH2 IS OVEREXPRESSED IN RHEUMATOID ARTHRITIS SYNOVIAL FIBROBLASTS (RASF) AND FURTHER INDUCED BY TUMOUR NECROSIS FACTOR ALPHA THROUGH THE NUCLEAR FACTOR KAPPA B AND JUN KINASE PATHWAYS. AS A TARGET GENE OF EZH2 THE AUTHORS IDENTIFIED SECRETED FRIZZLED-RELATED PROTEIN 1 (SFRP1), AN INHIBITOR OF WNT SIGNALLING, WHICH IS ASSOCIATED WITH THE ACTIVATION OF RASF, AND SHOW THAT SFRP1 EXPRESSION CORRELATES WITH THE OCCUPATION OF ITS PROMOTER WITH ACTIVATING AND SILENCING HISTONE MARKS. CONCLUSIONS: THESE DATA STRONGLY SUGGEST THAT THE CHRONIC INFLAMMATORY ENVIRONMENT OF THE RA JOINT INDUCES EZH2 AND THUS MIGHT CAUSE CHANGES IN THE EPIGENETIC PROGRAMMES OF SF. 2011 4 2067 23 EPIGENETIC CONTROL OF MACROPHAGE SHAPE TRANSITION TOWARDS AN ATYPICAL ELONGATED PHENOTYPE BY HISTONE DEACETYLASE ACTIVITY. INFLAMMATORY CHRONIC PATHOLOGIES ARE COMPLEX PROCESSES CHARACTERIZED BY AN IMBALANCE BETWEEN THE RESOLUTION OF THE INFLAMMATORY PHASE AND THE ESTABLISHMENT OF TISSUE REPAIR. THE MAIN PLAYERS IN THESE INFLAMMATORY PATHOLOGIES ARE BONE MARROW DERIVED MONOCYTES (BMDMS). HOWEVER, HOW MONOCYTE DIFFERENTIATION IS MODULATED TO GIVE RISE TO SPECIFIC MACROPHAGE SUBPOPULATIONS (M1 OR M2) THAT MAY EITHER MAINTAIN THE CHRONIC INFLAMMATORY PROCESS OR LEAD TO WOUND HEALING IS STILL UNCLEAR. CONSIDERING THAT INHIBITORS OF HISTONE DEACETYLASE (HDAC) HAVE AN ANTI-INFLAMMATORY ACTIVITY, WE ASKED WHETHER THIS ENZYME WOULD PLAY A ROLE ON MONOCYTE DIFFERENTIATION INTO M1 OR M2 PHENOTYPE AND IN THE CELL SHAPE TRANSITION THAT FOLLOWS. WE THEN INDUCED MURINE BONE MARROW PROGENITORS INTO MONOCYTE/MACROPHAGE DIFFERENTIATION PATHWAY USING MEDIA CONTAINING GM-CSF AND THE HDAC BLOCKER, TRICHOSTATIN A (TSA). WE FOUND THAT THE PHARMACOLOGICAL INHIBITION OF HDAC ACTIVITY LED TO A SHAPE TRANSITION FROM THE TYPICAL MACROPHAGE PANCAKE-LIKE SHAPE INTO AN ELONGATED MORPHOLOGY, WHICH WAS CORRELATED TO A MIXED M1/M2 PROFILE OF CYTOKINE AND CHEMOKINE SECRETION. OUR RESULTS PRESENT, FOR THE FIRST TIME, THAT HDAC ACTIVITY ACTS AS A REGULATOR OF MACROPHAGE DIFFERENTIATION IN THE ABSENCE OF LYMPHOCYTE STIMULI. WE PROPOSE THAT HDAC ACTIVITY DOWN REGULATES MACROPHAGE PLASTICITY FAVORING THE PRO-INFLAMMATORY PHENOTYPE. 2015 5 6117 25 THE EPIGENETIC DRUG TRICHOSTATIN A AMELIORATES EXPERIMENTAL AUTOIMMUNE ENCEPHALOMYELITIS VIA T CELL TOLERANCE INDUCTION AND IMPAIRED INFLUX OF T CELLS INTO THE SPINAL CORD. MULTIPLE SCLEROSIS IS A T CELL MEDIATED CHRONIC DEMYELINATING DISEASE OF THE CENTRAL NERVOUS SYSTEM. ALTHOUGH CURRENTLY AVAILABLE THERAPIES REDUCE RELAPSES, THEY DO NOT FACILITATE TOLERIZATION OF MYELIN ANTIGEN-SPECIFIC T LYMPHOCYTES TO ENSURE PROLONGED PROTECTION AGAINST MULTIPLE SCLEROSIS. HERE, WE SHOW THAT TREATMENT OF NOD MICE WITH THE HISTONE DEACETYLASE INHIBITOR, TRICHOSTATIN A AFFORDS ROBUST PROTECTION AGAINST MYELIN PEPTIDE INDUCED EXPERIMENTAL AUTOIMMUNE ENCEPHALOMYELITIS, A MOUSE MODEL OF MULTIPLE SCLEROSIS. PROTECTION WAS ACCOMPANIED BY HISTONE HYPERACETYLATION, AND REDUCED INFLAMMATION AND AXONAL DAMAGE IN THE SPINAL CORD. DRUG TREATMENT DIMINISHED THE GENERATION OF CD4(+) MEMORY T CELLS AND INDUCED TOLERANCE IN CD4(+) T CELLS RECOGNIZING THE IMMUNIZING MYELIN PEPTIDE. DURING THE EARLY IMMUNIZATION PERIOD, CD4(+) T CELLS PRODUCING GM-CSF+IFN-GAMMA, GM-CSF+IL-17A, AS WELL AS THOSE EXPRESSING BOTH IL-17A+IFN-GAMMA (DOUBLE-PRODUCERS) WERE DETECTED IN THE SECONDARY LYMPHOID ORGANS FOLLOWED BY THE APPEARANCE OF CELLS PRODUCING IFN-GAMMA AND GM-CSF. ON THE OTHER HAND, IFN-GAMMA PRODUCING TH1 CELLS APPEAR FIRST IN THE SPINAL CORD FOLLOWED BY CELLS PRODUCING IL-17A AND GM-CSF. TREATMENT WITH TRICHOSTATIN A SUBSTANTIALLY REDUCED THE FREQUENCIES OF ALL T CELLS SECRETING VARIOUS LYMPHOKINES BOTH IN THE PERIPHERY AND IN THE SPINAL CORD. THESE DATA INDICATE THAT EPIGENETIC MODIFICATIONS INDUCED BY HISTONE HYPERACETYLATION FACILITATES T CELL TOLERANCE INDUCTION IN THE PERIPHERY LEADING TO REDUCED MIGRATION OF T CELLS TO THE SPINAL CORD AND MITIGATION OF NEURONAL DAMAGE AND IMPROVED CLINICAL OUTCOME. THESE RESULTS SUGGEST THAT EPIGENETIC MODULATION OF THE GENOME MAY SIMILARLY OFFER BENEFITS TO MULTIPLE SCLEROSIS PATIENTS VIA ABROGATING THE FUNCTION OF ENCEPHALITOGENIC T LYMPHOCYTES WITHOUT EXERTING SEVERE SIDE EFFECTS ASSOCIATED WITH CURRENTLY USED DISEASE-MODIFYING THERAPIES. 2017 6 4298 24 MICRORNA-146A GOVERNS FIBROBLAST ACTIVATION AND JOINT PATHOLOGY IN ARTHRITIS. SYNOVIAL FIBROBLASTS ARE KEY CELLS ORCHESTRATING THE INFLAMMATORY RESPONSE IN ARTHRITIS. HERE WE DEMONSTRATE THAT LOSS OF MIR-146A, A KEY EPIGENETIC REGULATOR OF THE INNATE IMMUNE RESPONSE, LEADS TO INCREASED JOINT DESTRUCTION IN A TNF-DRIVEN MODEL OF ARTHRITIS BY SPECIFICALLY REGULATING THE BEHAVIOR OF SYNOVIAL FIBROBLASTS. ABSENCE OF MIR-146A IN SYNOVIAL FIBROBLASTS DISPLAY A HIGHLY DEREGULATED GENE EXPRESSION PATTERN AND ENHANCED PROLIFERATION IN VITRO AND IN VIVO. DEFICIENCY OF MIR-146A INDUCES DEREGULATION OF TUMOR NECROSIS FACTOR (TNF) RECEPTOR ASSOCIATED FACTOR 6 (TRAF6) IN SYNOVIAL FIBROBLASTS, LEADING TO INCREASED PROLIFERATION. IN ADDITION, LOSS OF MIR-146A SHIFTS THE METABOLIC STATE OF FIBROBLASTS TOWARDS GLYCOLYSIS AND AUGMENTS THE ABILITY OF SYNOVIAL FIBROBLASTS TO SUPPORT THE GENERATION OF OSTEOCLASTS BY CONTROLLING THE BALANCE OF OSTEOCLASTOGENIC REGULATORY FACTORS RECEPTOR ACTIVATOR OF NF-KAPPAB LIGAND (RANKL) AND OSTEOPROTEGERIN (OPG). BONE MARROW TRANSPLANTATION EXPERIMENTS CONFIRMED THE IMPORTANCE OF MIR-146A IN THE RADIORESISTANT MESENCHYMAL COMPARTMENT FOR THE CONTROL OF ARTHRITIS SEVERITY, IN PARTICULAR FOR INFLAMMATORY JOINT DESTRUCTION. THIS STUDY THEREFORE IDENTIFIES MICRORNA-146A AS AN IMPORTANT LOCAL EPIGENETIC REGULATOR OF THE INFLAMMATORY RESPONSE IN ARTHRITIS. IT IS A CENTRAL ELEMENT OF AN ANTI-INFLAMMATORY FEEDBACK LOOP IN RESIDENT SYNOVIAL FIBROBLASTS, WHO ARE ORCHESTRATING THE INFLAMMATORY RESPONSE IN CHRONIC ARTHRITIS. MIR-146A RESTRICTS THEIR ACTIVATION, THEREBY PREVENTING EXCESSIVE TISSUE DAMAGE DURING ARTHRITIS. 2017 7 855 22 CHROMATIN ACCESSIBILITY LANDSCAPES OF IMMUNE CELLS IN RHEUMATOID ARTHRITIS NOMINATE MONOCYTES IN DISEASE PATHOGENESIS. BACKGROUND: RHEUMATOID ARTHRITIS (RA) IS A CHRONIC, SYSTEMIC AUTOIMMUNE DISEASE THAT INVOLVES A VARIETY OF CELL TYPES. HOWEVER, HOW THE EPIGENETIC DYSREGULATIONS OF PERIPHERAL IMMUNE CELLS CONTRIBUTE TO THE PATHOGENESIS OF RA STILL REMAINS LARGELY UNCLEAR. RESULTS: HERE, WE ANALYSED THE GENOME-WIDE ACTIVE DNA REGULATORY ELEMENTS OF FOUR MAJOR IMMUNE CELLS, NAMELY MONOCYTES, B CELLS, CD4(+) T CELLS AND CD8(+) T CELLS, IN PERIPHERAL BLOOD OF RA PATIENTS, OSTEOARTHRITIS (OA) PATIENTS AND HEALTHY DONORS USING ASSAY OF TRANSPOSASE ACCESSIBLE CHROMATIN WITH SEQUENCING (ATAC-SEQ). WE FOUND A STRONG RA-ASSOCIATED CHROMATIN DYSREGULATION SIGNATURE IN MONOCYTES, BUT NO OTHER EXAMINED CELL TYPES. MOREOVER, WE FOUND THAT SERUM C-REACTIVE PROTEIN (CRP) CAN INDUCE THE RA-ASSOCIATED CHROMATIN DYSREGULATION IN MONOCYTES VIA IN VITRO EXPERIMENTS. AND THE EXTENT OF THIS DYSREGULATION WAS REGULATED THROUGH THE TRANSCRIPTION FACTOR FRA2. CONCLUSIONS: TOGETHER, OUR STUDY REVEALED A CRP-INDUCED PATHOGENIC CHROMATIN DYSREGULATION SIGNATURE IN MONOCYTES FROM RA PATIENTS AND PREDICTED THE RESPONSIBLE SIGNALLING PATHWAY AS POTENTIAL THERAPEUTIC TARGETS FOR THE DISEASE. 2021 8 6764 22 ZINC DEFICIENCY ENHANCED INFLAMMATORY RESPONSE BY INCREASING IMMUNE CELL ACTIVATION AND INDUCING IL6 PROMOTER DEMETHYLATION. SCOPE: ZINC DEFICIENCY RESULTS IN IMMUNE DYSFUNCTION AND PROMOTES SYSTEMIC INFLAMMATION. THE OBJECTIVE OF THIS STUDY WAS TO EXAMINE THE EFFECTS OF ZINC DEFICIENCY ON CELLULAR IMMUNE ACTIVATION AND EPIGENETIC MECHANISMS THAT PROMOTE INFLAMMATION. THIS WORK IS POTENTIALLY RELEVANT TO THE AGING POPULATION GIVEN THAT AGE-RELATED IMMUNE DEFECTS, INCLUDING CHRONIC INFLAMMATION, COINCIDE WITH DECLINING ZINC STATUS. METHODS AND RESULTS: AN IN VITRO CELL CULTURE SYSTEM AND THE AGED MOUSE MODEL WERE USED TO CHARACTERIZE IMMUNE ACTIVATION AND DNA METHYLATION PROFILES THAT MAY CONTRIBUTE TO THE ENHANCED PROINFLAMMATORY RESPONSE MEDIATED BY ZINC DEFICIENCY. ZINC DEFICIENCY UPREGULATED CELL ACTIVATION MARKERS ICAM1, MHC CLASS II, AND CD86 IN THP1 CELLS, WHICH COINCIDED WITH INCREASED IL1BETA AND IL6 RESPONSES FOLLOWING LPS STIMULATION. A DECREASED ZINC STATUS IN AGED MICE WAS SIMILARLY ASSOCIATED WITH INCREASED ICAM1 AND IL6 GENE EXPRESSION. REDUCED IL6 PROMOTER METHYLATION WAS OBSERVED IN ZINC-DEFICIENT THP1 CELLS, AS WELL AS IN AGED MICE AND HUMAN LYMPHOBLASTOID CELL LINES DERIVED FROM AGED INDIVIDUALS. CONCLUSION: ZINC DEFICIENCY INDUCED INFLAMMATORY RESPONSE IN PART BY ELICITING ABERRANT IMMUNE CELL ACTIVATION AND ALTERED PROMOTER METHYLATION. OUR RESULTS SUGGESTED POTENTIAL INTERACTIONS BETWEEN ZINC STATUS, EPIGENETICS, AND IMMUNE FUNCTION, AND HOW THEIR DYSREGULATION COULD CONTRIBUTE TO CHRONIC INFLAMMATION. 2015 9 5592 22 ROLE OF TUMOR NECROSIS FACTOR-ALPHA IN THE HUMAN SYSTEMIC ENDOTOXIN-INDUCED TRANSCRIPTOME. TNFALPHA HAS BEEN IMPLICATED IN THE PATHOGENESIS OF VARIOUS INFLAMMATORY DISEASES. DIFFERENT STRATEGIES TO INHIBIT TNFALPHA IN PATIENTS WITH SEPSIS AND CHRONIC INFLAMMATORY CONDITIONS HAVE SHOWN CONTRASTING OUTCOMES. ALTHOUGH TNFALPHA INHIBITORS ARE WIDELY USED IN CLINICAL PRACTICE, THE IMPACT OF TNFALPHA ANTAGONISM ON WHITE BLOOD CELL GENE EXPRESSION PROFILES DURING ACUTE INFLAMMATION IN HUMANS IN VIVO HAS NOT BEEN ASSESSED. WE HERE LEVERAGED THE ESTABLISHED MODEL OF HUMAN ENDOTOXEMIA TO EXAMINE THE EFFECT OF THE TNFALPHA ANTAGONIST, ETANERCEPT, ON THE GENOME-WIDE TRANSCRIPTIONAL RESPONSES IN CIRCULATING LEUKOCYTES INDUCED BY INTRAVENOUS LPS ADMINISTRATION IN MALE SUBJECTS. ETANERCEPT PRE-TREATMENT RESULTED IN A MARKEDLY DAMPENED TRANSCRIPTIONAL RESPONSE TO LPS. GENE CO-EXPRESSION NETWORK ANALYSIS REVEALED THIS LPS-INDUCED TRANSCRIPTOME CAN BE CATEGORIZED AS TNFALPHA RESPONSIVE AND NON-RESPONSIVE MODULES. HIGHLY SIGNIFICANT TNFALPHA RESPONSIVE MODULES INCLUDE NF-KB SIGNALING, ANTIVIRAL RESPONSES AND T-CELL MEDIATED RESPONSES. WITHIN THESE TNFALPHA RESPONSIVE MODULES WE DELINEATE FUNDAMENTAL GENES INVOLVED IN EPIGENETIC MODIFICATIONS, TRANSCRIPTIONAL INITIATION AND ELONGATION. THUS, WE PROVIDE COMPREHENSIVE INFORMATION ABOUT MOLECULAR PATHWAYS THAT MIGHT BE TARGETED BY THERAPEUTIC INTERVENTIONS THAT SEEK TO INHIBIT TNFALPHA ACTIVITY DURING HUMAN INFLAMMATORY DISEASES. 2013 10 5975 25 TET1 IS AN IMPORTANT TRANSCRIPTIONAL ACTIVATOR OF TNFALPHA EXPRESSION IN MACROPHAGES. ACTIVATION OF MACROPHAGES AND OVEREXPRESSION OF TNFALPHA IS ASSOCIATED WITH THE PATHOGENESIS OF CHRONIC INFLAMMATORY DISEASES. HOWEVER, THE MECHANISMS LEADING TO TNFALPHA OVEREXPRESSION ARE STILL UNKNOWN. 5-METHYLOCYTOSINE (5-MC) IS AN EPIGENETIC MODIFICATION THAT IS ASSOCIATED WITH SILENCED GENES. RECENT STUDIES SHOWED THAT IT IS CONVERTED TO 5-HYDROXYLMETHYLOCYTOSINE (5-HMC) AND REACTIVATES GENE EXPRESSION THROUGH THE ACTION OF THE FAMILY OF TEN-ELEVEN-TRANSLOCATION (TET1-3) ENZYMES. IN THIS STUDY, WE SHOW THAT 5-HMC LEVELS ARE INCREASED GLOBALLY AND SPECIFICALLY IN THE TNFALPHA PROMOTER DURING THE DIFFERENTIATION OF MONOCYTES TO MACROPHAGES. IN ADDITION, THE LEVELS OF 5-HMC ARE INCREASED UPON LPS STIMULATION OF MACROPHAGES. FURTHERMORE, CRIPSR STABLE KNOCKOUT OF TET1 DECREASES THE EXPRESSION OF TNFALPHA AND OTHER PRO-INFLAMMATORY CYTOKINES. IN CONCLUSION, WE SHOWED THAT TET1 CONTRIBUTES TO THE ACTIVATION OF MACROPHAGES POSSIBLY THROUGH REGULATION OF 5-HYDROXYMETHYLATION IN THE PROMOTER OF PRO-INFLAMMATORY CYTOKINE GENES. THE TET1 ENZYME COULD BE A PROMISING THERAPEUTIC TARGET TO INHIBIT THE PERSISTENT INFLAMMATION CAUSED BY MACROPHAGES IN CHRONIC INFLAMMATORY DISEASES. 2019 11 1479 19 DIVERSE TARGETS OF THE TRANSCRIPTION FACTOR STAT3 CONTRIBUTE TO T CELL PATHOGENICITY AND HOMEOSTASIS. STAT3, AN ESSENTIAL TRANSCRIPTION FACTOR WITH PLEIOTROPIC FUNCTIONS, PLAYS CRITICAL ROLES IN THE PATHOGENESIS OF AUTOIMMUNITY. DESPITE RECENT DATA LINKING STAT3 WITH INFLAMMATORY BOWEL DISEASE, EXACTLY HOW IT CONTRIBUTES TO CHRONIC INTESTINAL INFLAMMATION IS NOT KNOWN. USING A T CELL TRANSFER MODEL OF COLITIS, WE FOUND THAT STAT3 EXPRESSION IN T CELLS WAS ESSENTIAL FOR THE INDUCTION OF BOTH COLITIS AND SYSTEMIC INFLAMMATION. STAT3 WAS CRITICAL IN MODULATING THE BALANCE OF T HELPER 17 (TH17) AND REGULATORY T (TREG) CELLS, AS WELL AS IN PROMOTING CD4(+) T CELL PROLIFERATION. WE USED CHROMATIN IMMUNOPRECIPITATION AND MASSIVE PARALLEL SEQUENCING (CHIP-SEQ) TO DEFINE THE GENOME-WIDE TARGETS OF STAT3 IN CD4(+) T CELLS. WE FOUND THAT STAT3 BOUND TO MULTIPLE GENES INVOLVED IN TH17 CELL DIFFERENTIATION, CELL ACTIVATION, PROLIFERATION, AND SURVIVAL, REGULATING BOTH EXPRESSION AND EPIGENETIC MODIFICATIONS. THUS, STAT3 ORCHESTRATES MULTIPLE CRITICAL ASPECTS OF T CELL FUNCTION IN INFLAMMATION AND HOMEOSTASIS. 2010 12 4563 29 MYELOID DNA METHYLTRANSFERASE3B DEFICIENCY AGGRAVATES PULMONARY FIBROSIS BY ENHANCING PROFIBROTIC MACROPHAGE ACTIVATION. BACKGROUND: IDIOPATHIC PULMONARY FIBROSIS (IPF) IS A CHRONIC, PROGRESSIVE AND SEVERE DISEASE CHARACTERIZED BY EXCESSIVE MATRIX DEPOSITION IN THE LUNGS. MACROPHAGES PLAY CRUCIAL ROLES IN MAINTAINING LUNG HOMEOSTASIS BUT ARE ALSO CENTRAL IN THE PATHOGENESIS OF LUNG DISEASES LIKE PULMONARY FIBROSIS. ESPECIALLY, MACROPHAGE POLARIZATION/ACTIVATION SEEMS TO PLAY A CRUCIAL ROLE IN PATHOLOGY AND EPIGENETIC REPROGRAMING IS WELL-KNOWN TO REGULATE MACROPHAGE POLARIZATION. DNA METHYLATION ALTERATIONS IN IPF LUNGS HAVE BEEN WELL DOCUMENTED, BUT THE ROLE OF DNA METHYLATION IN SPECIFIC CELL TYPES, ESPECIALLY MACROPHAGES, IS POORLY DEFINED. METHODS: IN ORDER TO DETERMINE THE ROLE OF DNA METHYLATION IN MACROPHAGES DURING PULMONARY FIBROSIS, WE SUBJECTED MACROPHAGE SPECIFIC DNA METHYLTRANSFERASE (DNMT)3B, WHICH MEDIATES THE DE NOVO DNA METHYLATION, DEFICIENT MICE TO THE BLEOMYCIN-INDUCED PULMONARY FIBROSIS MODEL. MACROPHAGE POLARIZATION AND FIBROTIC PARAMETERS WERE EVALUATED AT 21 DAYS AFTER BLEOMYCIN ADMINISTRATION. DNMT3B KNOCKOUT AND WILD TYPE BONE MARROW-DERIVED MACROPHAGES WERE STIMULATED WITH EITHER INTERLEUKIN (IL)4 OR TRANSFORMING GROWTH FACTOR BETA 1 (TGFB1) IN VITRO, AFTER WHICH PROFIBROTIC GENE EXPRESSION AND DNA METHYLATION AT THE ARG1 PROMOTOR WERE DETERMINED. RESULTS: WE SHOW THAT DNMT3B DEFICIENCY PROMOTES ALTERNATIVE MACROPHAGE POLARIZATION INDUCED BY IL4 AND TGFB1 IN VITRO AND ALSO ENHANCES PROFIBROTIC MACROPHAGE POLARIZATION IN THE ALVEOLAR SPACE DURING PULMONARY FIBROSIS IN VIVO. MOREOVER, MYELOID SPECIFIC DELETION OF DNMT3B PROMOTED THE DEVELOPMENT OF EXPERIMENTAL PULMONARY FIBROSIS. CONCLUSIONS: IN SUMMARY, THESE DATA SUGGEST THAT MYELOID DNMT3B REPRESSES FIBROTIC MACROPHAGE POLARIZATION AND PROTECTS AGAINST BLEOMYCIN INDUCED PULMONARY FIBROSIS. 2022 13 2026 20 EPIGENETIC CHANGES IN BONE MARROW PROGENITOR CELLS INFLUENCE THE INFLAMMATORY PHENOTYPE AND ALTER WOUND HEALING IN TYPE 2 DIABETES. CLASSICALLY ACTIVATED (M1) MACROPHAGES ARE KNOWN TO PLAY A ROLE IN THE DEVELOPMENT OF CHRONIC INFLAMMATION ASSOCIATED WITH IMPAIRED WOUND HEALING IN TYPE 2 DIABETES (T2D); HOWEVER, THE MECHANISM RESPONSIBLE FOR THE DOMINANT PROINFLAMMATORY (M1) MACROPHAGE PHENOTYPE IN T2D WOUNDS IS UNKNOWN. SINCE EPIGENETIC ENZYMES CAN DIRECT MACROPHAGE PHENOTYPES, WE ASSESSED THE ROLE OF HISTONE METHYLATION IN BONE MARROW (BM) STEM/PROGENITOR CELLS IN THE PROGRAMMING OF MACROPHAGES TOWARD A PROINFLAMMATORY PHENOTYPE. WE HAVE FOUND THAT A REPRESSIVE HISTONE METHYLATION MARK, H3K27ME3, IS DECREASED AT THE PROMOTER OF THE IL-12 GENE IN BM PROGENITORS AND THIS EPIGENETIC SIGNATURE IS PASSED DOWN TO WOUND MACROPHAGES IN A MURINE MODEL OF GLUCOSE INTOLERANCE (DIET-INDUCED OBESE). THESE EPIGENETICALLY "PREPROGRAMMED" MACROPHAGES RESULT IN POISED MACROPHAGES IN PERIPHERAL TISSUE AND NEGATIVELY IMPACT WOUND REPAIR. WE FOUND THAT IN DIABETIC CONDITIONS THE H3K27 DEMETHYLASE JMJD3 DRIVES IL-12 PRODUCTION IN MACROPHAGES AND THAT IL-12 PRODUCTION CAN BE MODULATED BY INHIBITING JMJD3. USING HUMAN T2D TISSUE AND MURINE MODELS, WE HAVE IDENTIFIED A PREVIOUSLY UNRECOGNIZED MECHANISM BY WHICH MACROPHAGES ARE PROGRAMMED TOWARD A PROINFLAMMATORY PHENOTYPE, ESTABLISHING A PATTERN OF UNRESTRAINED INFLAMMATION ASSOCIATED WITH NONHEALING WOUNDS. HENCE, HISTONE DEMETHYLASE INHIBITOR-BASED THERAPY MAY REPRESENT A NOVEL TREATMENT OPTION FOR DIABETIC WOUNDS. 2015 14 6110 22 THE EPIGENETIC ALTERATION OF SYNOVIAL CELL GENE EXPRESSION IN RHEUMATOID ARTHRITIS AND THE ROLES OF NUCLEAR FACTOR KAPPAB AND NOTCH SIGNALING PATHWAYS. RHEUMATOID ARTHRITIS (RA) IS A COMPLEX PROCESS OF CHRONIC AND PROGRESSIVE INFLAMMATION ASSOCIATED WITH ACTIVATION OF NUMEROUS SIGNALING MOLECULES AND TRANSCRIPTION FACTORS AND HYPERPROLIFERATION OF SYNOVIOCYTES OF THE AFFECTED JOINTS, ALTHOUGH THE GREATER PART OF ITS PATHOPHYSIOLOGICAL PROCESS IS EXPLAINED BY ACTIVATION OF NUCLEAR FACTOR KAPPAB (NF-KAPPAB). FOR EXAMPLE, THE SELF-PERPETUATING NATURE OF THE RHEUMATOID INFLAMMATION IS ASCRIBABLE TO OVEREXPRESSION OF THE PROINFLAMMATORY CYTOKINES TUMOR NECROSIS FACTOR ALPHA AND INTERLEUKIN-1BETA, KNOWN TO ELICIT THE ACTIVATION CASCADE FOR NF-KAPPAB AND ACTIVATOR PROTEIN-1 THAT ARE RESPONSIBLE FOR TRANSCRIPTIONAL INDUCTION OF THESE CYTOKINES AMONG OTHER TARGET GENES, WHICH CONFORM A POSITIVE FEEDBACK LOOP FOR CONTINUATION AND EXPANSION OF THE INFLAMMATORY RESPONSES. IN ADDITION, COMPARATIVE GENE EXPRESSION PROFILE ANALYSES HAVE REVEALED ACTIVATION OF A NUMBER OF GENES THAT EXPLAIN THE "TRANSFORMED-LIKE" PHENOTYPE OF SYNOVIOCYTES. AMONG THE GENES EXPRESSED IN RHEUMATOID SYNOVIOCYTES UPON INFLAMMATORY STIMULI, INDUCTION OF GENE EXPRESSION OF NOTCH PROTEINS AND ITS LIGAND HAVE BEEN FOUND. POSSIBLE ROLES OF NOTCH SIGNALING IN RA SYNOVIOCYTES ARE DISCUSSED. 2005 15 5279 29 PROMOTER-SPECIFIC RELEVANCE OF HISTONE MODIFICATIONS INDUCED BY DEXAMETHASONE DURING THE REGULATION OF PRO-INFLAMMATORY MEDIATORS. GLUCOCORTICOSTEROIDS (GCS) ARE WIDELY USED TO TREAT DIFFERENT KINDS OF CHRONIC INFLAMMATORY AND IMMUNE DISEASES THROUGH TRANSCRIPTIONAL REGULATION OF INFLAMMATORY GENES. MODULATION OF GENE EXPRESSION BY GCS IS KNOWN TO OCCUR THROUGH DIVERSE MECHANISMS OF VARYING RELEVANCE TO SPECIFIC CLASSES OF GENES. EPIGENETIC MODIFICATIONS ARE INDEED A PIVOTAL REGULATORY FEATURE OF GLUCOCORTICOID RECEPTOR AND OTHER TRANSCRIPTION FACTORS. IN THIS STUDY, HISTONE POST-TRANSLATIONAL MODIFICATIONS WERE INVESTIGATED FOR THEIR INVOLVEMENT IN THE REGULATION OF SELECTED PRO-INFLAMMATORY GENES - EXPRESSED IN HUMAN MONOCYTE-DERIVED MACROPHAGES - IN RESPONSE TO TREATMENT WITH SYNTHETIC GC DEXAMETHASONE (DEX). WE SHOW THAT HISTONE TAIL ACETYLATION STATUS IS MODIFIED FOLLOWING DEX ADMINISTRATION, THROUGH DISTINCT AND ALTERNATIVE MECHANISMS AT THE PROMOTERS OF INTERLEUKIN-8 AND INTERLEUKIN-23. IN ADDITION TO HISTONE H3 ACETYLATION, OUR RESULTS DEMONSTRATE THAT H3 LYSINE 4 TRIMETHYLATION IS AFFECTED FOLLOWING DRUG TREATMENT. 2014 16 2641 29 EPIGENOMIC AND TRANSCRIPTOMIC ANALYSES REVEAL DIFFERENCES BETWEEN LOW-GRADE INFLAMMATION AND SEVERE EXHAUSTION IN LPS-CHALLENGED MURINE MONOCYTES. EMERGING STUDIES SUGGEST THAT MONOCYTES CAN BE TRAINED BY BACTERIAL ENDOTOXIN TO ADOPT DISTINCT MEMORY STATES RANGING FROM LOW-GRADE INFLAMMATION TO IMMUNE EXHAUSTION. WHILE LOW-GRADE INFLAMMATION MAY CONTRIBUTE TO THE PATHOGENESIS OF CHRONIC DISEASES, EXHAUSTED MONOCYTES WITH PATHOGENIC AND IMMUNE-SUPPRESSIVE CHARACTERISTICS MAY UNDERLIE THE PATHOGENESIS OF POLYMICROBIAL SEPSIS INCLUDING COVID-19. HOWEVER, DETAILED PROCESSES BY WHICH THE DYNAMIC ADAPTION OF MONOCYTES OCCUR REMAIN POORLY UNDERSTOOD. HERE WE EXPOSED MURINE BONE-MARROW DERIVED MONOCYTES TO CHRONIC LIPOPOLYSACCHARIDE (LPS) STIMULATION AT LOW-DOSE OR HIGH-DOSE, AS WELL AS A PBS CONTROL. THE CELLS WERE PROFILED FOR GENOME-WIDE H3K27AC MODIFICATION AND GENE EXPRESSION. THE GENE EXPRESSION OF TRAM-DEFICIENT AND IRAK-M-DEFICIENT MONOCYTES WITH LPS EXPOSURE WAS ALSO ANALYZED. WE DISCOVER THAT LOW-GRADE INFLAMMATION PREFERENTIALLY UTILIZES THE TRAM-DEPENDENT PATHWAY OF TLR4 SIGNALING, AND INDUCES THE EXPRESSION OF INTERFERON RESPONSE GENES. IN CONTRAST, HIGH DOSE LPS UNIQUELY UPREGULATES EXHAUSTION SIGNATURES WITH METABOLIC AND PROLIFERATIVE PATHWAYS. THE EXTENSIVE DIFFERENCES IN THE EPIGENOMIC LANDSCAPE BETWEEN LOW-DOSE AND HIGH-DOSE CONDITIONS SUGGEST THE IMPORTANCE OF EPIGENETIC REGULATIONS IN DRIVING DIFFERENTIAL RESPONSES. OUR DATA PROVIDE POTENTIAL TARGETS FOR FUTURE MECHANISTIC OR THERAPEUTIC STUDIES. 2022 17 5417 31 REGULATION OF DNA METHYLATION IN RHEUMATOID ARTHRITIS SYNOVIOCYTES. RHEUMATOID ARTHRITIS (RA) IS A CHRONIC INFLAMMATORY DISEASE IN WHICH FIBROBLAST-LIKE SYNOVIOCYTES (FLS) EXHIBIT AN AGGRESSIVE PHENOTYPE. ALTHOUGH THE MECHANISMS RESPONSIBLE ARE NOT WELL DEFINED, EPIGENETIC DETERMINANTS SUCH AS DNA METHYLATION MIGHT CONTRIBUTE. DNA METHYLTRANSFERASES (DNMTS) ARE CRITICAL ENZYMES THAT ESTABLISH AND MAINTAIN DNA METHYLATION. WE EVALUATED WHETHER PROINFLAMMATORY CYTOKINES MIGHT CONTRIBUTE TO DIFFERENTIAL DNA METHYLATION PREVIOUSLY DESCRIBED IN RA FLS THROUGH ALTERED DNMT EXPRESSION. FLS WERE OBTAINED FROM RA AND OSTEOARTHRITIS (OA) SYNOVIUM AT THE TIME OF TOTAL JOINT REPLACEMENT. GENE EXPRESSION WAS DETERMINED BY QUANTITATIVE REAL-TIME PCR AND PROTEIN EXPRESSION BY WESTERN BLOT ANALYSIS. DNMT ACTIVITY WAS MEASURED WITH A FUNCTIONAL ASSAY, AND GLOBAL METHYLATION WAS DETERMINED BY AN IMMUNOASSAY THAT DETECTS METHYLCYTOSINE. RESTING EXPRESSION OF DNMT1, -3A, AND -3B MRNA WERE SIMILAR IN RA AND OA FLS. WESTERN BLOT SHOWED ABUNDANT DNMT1 AND DNMT3A PROTEIN. EXPOSURE TO IL-1 DECREASED DNMT1 AND DNMT3A MRNA EXPRESSION IN FLS. DOSE RESPONSES DEMONSTRATED DECREASED DNMT EXPRESSION AT CONCENTRATIONS AS LOW AS 1 PG/ML OF IL-1. DNMT MRNA LEVELS DECREASED RAPIDLY, WITH SIGNIFICANT SUPPRESSION AFTER 2-8 H OF IL-1 STIMULATION. IL-1 STIMULATION OF OA FLS DID NOT AFFECT METHYLATION OF LINE1 SITES BUT LED TO DEMETHYLATION OF A CHI3L1 LOCUS THAT IS HYPOMETHYLATED IN RA FLS. CHRONIC IL-1 STIMULATION ALSO MIMICKED THE EFFECT OF A DNMT INHIBITOR ON FLS GENE EXPRESSION. EXPOSURE TO PROINFLAMMATORY MEDIATORS REVERSIBLY ALTERS DNA METHYLATION IN FLS BY DECREASING DNMT EXPRESSION AND FUNCTION. THESE DATA SUGGEST THAT IL-1 CAN POTENTIALLY IMPRINT CELLS IN CHRONIC INFLAMMATORY DISEASES. 2013 18 744 35 CANNABINOID WIN55,212-2 REPROGRAMS MONOCYTES AND MACROPHAGES TO INHIBIT LPS-INDUCED INFLAMMATION. INTRODUCTION: CHRONIC OR UNCONTROLLED ACTIVATION OF MYELOID CELLS INCLUDING MONOCYTES, MACROPHAGES AND DENDRITIC CELLS (DCS) IS A HALLMARK OF IMMUNE-MEDIATED INFLAMMATORY DISORDERS. THERE IS AN URGENT NEED FOR THE DEVELOPMENT OF NOVEL DRUGS WITH THE CAPACITY TO IMPAIR INNATE IMMUNE CELL OVERACTIVATION UNDER INFLAMMATORY CONDITIONS. COMPELLING EVIDENCE POINTED OUT CANNABINOIDS AS POTENTIAL THERAPEUTIC TOOLS WITH ANTI-INFLAMMATORY AND IMMUNOMODULATORY CAPACITY. WIN55,212-2, A NON-SELECTIVE SYNTHETIC CANNABINOID AGONIST, DISPLAYS PROTECTIVE EFFECTS IN SEVERAL INFLAMMATORY CONDITIONS BY MECHANISMS PARTIALLY DEPENDING ON THE GENERATION OF TOLEROGENIC DCS ABLE TO INDUCE FUNCTIONAL REGULATORY T CELLS (TREGS). HOWEVER, ITS IMMUNOMODULATORY CAPACITY ON OTHER MYELOID CELLS SUCH AS MONOCYTES AND MACROPHAGES REMAINS INCOMPLETELY UNDERSTOOD. METHODS: HUMAN MONOCYTE-DERIVED DCS (HMODCS) WERE DIFFERENTIATED IN THE ABSENCE (CONVENTIONAL HMODCS) OR PRESENCE OF WIN55,212-2 (WIN-HMODCS). CELLS WERE STIMULATED WITH LPS, COCULTURED WITH NAIVE T LYMPHOCYTES AND THEIR CYTOKINE PRODUCTION AND ABILITY TO INDUCE T CELL RESPONSES WERE ANALYSED BY ELISA OR FLOW CYTOMETRY. TO EVALUATE THE EFFECT OF WIN55,212-2 IN MACROPHAGE POLARIZATION, HUMAN AND MURINE MACROPHAGES WERE ACTIVATED WITH LPS OR LPS/IFNGAMMA, IN THE PRESENCE OR ABSENCE OF THE CANNABINOID. CYTOKINE, COSTIMULATORY MOLECULES AND INFLAMMASOME MARKERS WERE ASSAYED. METABOLIC AND CHROMATIN IMMUNOPRECIPITATION ASSAYS WERE ALSO PERFORMED. FINALLY, THE PROTECTIVE CAPACITY OF WIN55,212-2 WAS STUDIED IN VIVO IN BALB/C MICE AFTER INTRAPERITONEAL INJECTION WITH LPS. RESULTS: WE SHOW FOR THE FIRST TIME THAT THE DIFFERENTIATION OF HMODCS IN THE PRESENCE OF WIN55,212-2 GENERATES TOLEROGENIC WIN-HMODCS THAT ARE LESS RESPONSIVE TO LPS STIMULATION AND ABLE TO PRIME TREGS. WIN55,212-2 ALSO IMPAIRS THE PRO-INFLAMMATORY POLARIZATION OF HUMAN MACROPHAGES BY INHIBITING CYTOKINE PRODUCTION, INFLAMMASOME ACTIVATION AND RESCUING MACROPHAGES FROM PYROPTOTIC CELL DEATH. MECHANISTICALLY, WIN55,212-2 INDUCED A METABOLIC AND EPIGENETIC SHIFT IN MACROPHAGES BY DECREASING LPS-INDUCED MTORC1 SIGNALING, COMMITMENT TO GLYCOLYSIS AND ACTIVE HISTONE MARKS IN PRO-INFLAMMATORY CYTOKINE PROMOTERS. WE CONFIRMED THESE DATA IN EX VIVO LPS-STIMULATED PERITONEAL MACROPHAGES (PMPHIS), WHICH WERE ALSO SUPPORTED BY THE IN VIVO ANTI-INFLAMMATORY CAPACITY OF WIN55,212-2 IN A LPS-INDUCED SEPSIS MOUSE MODEL. CONCLUSION: OVERALL, WE SHED LIGHT INTO THE MOLECULAR MECHANISMS BY WHICH CANNABINOIDS EXERT ANTI-INFLAMMATORY PROPERTIES IN MYELOID CELLS, WHICH MIGHT WELL CONTRIBUTE TO THE FUTURE RATIONAL DESIGN OF NOVEL THERAPEUTIC STRATEGIES FOR INFLAMMATORY DISORDERS. 2023 19 3422 30 HUMAN MONOCYTE-TO-MACROPHAGE DIFFERENTIATION INVOLVES HIGHLY LOCALIZED GAIN AND LOSS OF DNA METHYLATION AT TRANSCRIPTION FACTOR BINDING SITES. BACKGROUND: MACROPHAGES AND THEIR PRECURSORS MONOCYTES PLAY A KEY ROLE IN INFLAMMATION AND CHRONIC INFLAMMATORY DISORDERS. MONOCYTE-TO-MACROPHAGE DIFFERENTIATION AND ACTIVATION PROGRAMS ARE ACCOMPANIED BY SIGNIFICANT EPIGENETIC REMODELING WHERE DNA METHYLATION ASSOCIATES WITH CELL IDENTITY. HERE WE SHOW THAT DNA METHYLATION CHANGES CHARACTERISTIC FOR MONOCYTE-TO-MACROPHAGE DIFFERENTIATION OCCUR AT TRANSCRIPTION FACTOR BINDING SITES, AND, IN CONTRAST TO WHAT WAS PREVIOUSLY DESCRIBED, ARE GENERALLY HIGHLY LOCALIZED AND ENCOMPASS BOTH LOSSES AND GAINS OF DNA METHYLATION. RESULTS: WE COMPARED GENOME-WIDE DNA METHYLATION ACROSS 440,292 CPG SITES BETWEEN HUMAN MONOCYTES, NAIVE MACROPHAGES AND MACROPHAGES FURTHER ACTIVATED TOWARD A PRO-INFLAMMATORY STATE (USING LPS/IFNGAMMA), AN ANTI-INFLAMMATORY STATE (IL-4) OR FOAM CELLS (OXLDL AND ACLDL). MOREOVER, WE INTEGRATED THESE DATA WITH PUBLIC WHOLE-GENOME SEQUENCING DATA ON MONOCYTES AND MACROPHAGES TO DEMARCATE DIFFERENTIALLY METHYLATED REGIONS. OUR ANALYSIS SHOWED THAT DIFFERENTIAL DNA METHYLATION WAS MOST PRONOUNCED DURING MONOCYTE-TO-MACROPHAGE DIFFERENTIATION, WAS TYPICALLY RESTRICTED TO SINGLE CPGS OR VERY SHORT REGIONS, AND CO-LOCALIZED WITH LINEAGE-SPECIFIC ENHANCERS IRRESPECTIVE OF WHETHER IT CONCERNS GAIN OR LOSS OF METHYLATION. FURTHERMORE, DIFFERENTIALLY METHYLATED CPGS WERE LOCATED AT SITES CHARACTERIZED BY INCREASED BINDING OF TRANSCRIPTION FACTORS KNOWN TO BE INVOLVED IN MONOCYTE-TO-MACROPHAGE DIFFERENTIATION INCLUDING C/EBP AND ETS FOR GAIN AND AP-1 FOR LOSS OF METHYLATION. CONCLUSION: OUR STUDY HIGHLIGHTS THE INVOLVEMENT OF SUBTLE, YET HIGHLY LOCALIZED REMODELING OF DNA METHYLATION AT REGULATORY REGIONS IN CELL DIFFERENTIATION. 2019 20 2228 17 EPIGENETIC MODIFICATIONS OF HISTONES IN PERIODONTAL DISEASE. PERIODONTITIS IS A CHRONIC INFECTIOUS DISEASE DRIVEN BY DYSBIOSIS, AN IMBALANCE BETWEEN COMMENSAL BACTERIA AND THE HOST ORGANISM. PERIODONTITIS IS A LEADING CAUSE OF TOOTH LOSS IN ADULTS AND OCCURS IN ABOUT 50% OF THE US POPULATION. IN ADDITION TO THE CLINICAL CHALLENGES ASSOCIATED WITH TREATING PERIODONTITIS, THE PROGRESSION AND CHRONIC NATURE OF THIS DISEASE SERIOUSLY AFFECT HUMAN HEALTH. EMERGING EVIDENCE SUGGESTS THAT PERIODONTITIS IS ASSOCIATED WITH MECHANISMS BEYOND BACTERIA-INDUCED PROTEIN AND TISSUE DEGRADATION. HERE, WE HYPOTHESIZE THAT BACTERIA ARE ABLE TO INDUCE EPIGENETIC MODIFICATIONS IN ORAL EPITHELIAL CELLS MEDIATED BY HISTONE MODIFICATIONS. IN THIS STUDY, WE FOUND THAT DYSBIOSIS IN VIVO LED TO EPIGENETIC MODIFICATIONS, INCLUDING ACETYLATION OF HISTONES AND DOWNREGULATION OF DNA METHYLTRANSFERASE 1. IN ADDITION, IN VITRO EXPOSURE OF ORAL EPITHELIAL CELLS TO LIPOPOLYSACCHARIDES RESULTED IN HISTONE MODIFICATIONS, ACTIVATION OF TRANSCRIPTIONAL COACTIVATORS, SUCH AS P300/CBP, AND ACCUMULATION OF NUCLEAR FACTOR-KAPPAB (NF-KAPPAB). GIVEN THAT ORAL EPITHELIAL CELLS ARE THE FIRST LINE OF DEFENSE FOR THE PERIODONTIUM AGAINST BACTERIA, WE ALSO EVALUATED WHETHER ACTIVATION OF PATHOGEN RECOGNITION RECEPTORS INDUCED HISTONE MODIFICATIONS. WE FOUND THAT ACTIVATION OF THE TOLL-LIKE RECEPTORS 1, 2, AND 4 AND THE NUCLEOTIDE-BINDING OLIGOMERIZATION DOMAIN PROTEIN 1 INDUCED HISTONE ACETYLATION IN ORAL EPITHELIAL CELLS. OUR FINDINGS CORROBORATE THE EMERGING CONCEPT THAT EPIGENETIC MODIFICATIONS PLAY A ROLE IN THE DEVELOPMENT OF PERIODONTITIS. 2016