1 2425 108 EPIGENETIC SILENCING OF IRF1 DYSREGULATES TYPE III INTERFERON RESPONSES TO RESPIRATORY VIRUS INFECTION IN EPITHELIAL TO MESENCHYMAL TRANSITION. CHRONIC OXIDATIVE INJURY PRODUCED BY AIRWAY DISEASE TRIGGERS A TRANSFORMING GROWTH FACTOR-BETA (TGF-BETA)-MEDIATED EPIGENETIC REPROGRAMMING KNOWN AS THE EPITHELIAL-MESENCHYMAL TRANSITION (EMT). WE OBSERVE THAT EMT SILENCES PROTECTIVE MUCOSAL INTERFERON (IFN)-I AND III PRODUCTION ASSOCIATED WITH ENHANCED RHINOVIRUS (RV) AND RESPIRATORY SYNCYTIAL VIRUS (RSV) REPLICATION. MESENCHYMAL TRANSITIONED CELLS ARE DEFECTIVE IN INDUCIBLE INTERFERON REGULATORY FACTOR 1 (IRF1) EXPRESSION BY OCCLUDING RELA AND IRF3 ACCESS TO THE PROMOTER. IRF1 IS NECESSARY FOR THE EXPRESSION OF TYPE III IFNS (IFNLS 1 AND 2/3). INDUCED BY THE EMT, ZINC FINGER E-BOX BINDING HOMEOBOX 1 (ZEB1) BINDS AND SILENCES IRF1. ECTOPIC ZEB1 IS SUFFICIENT FOR IRF1 SILENCING, WHEREAS ZEB1 KNOCKDOWN PARTIALLY RESTORES IRF1-IFNL UPREGULATION. ZEB1 SILENCES IRF1 THROUGH THE CATALYTIC ACTIVITY OF THE ENHANCER OF ZESTE 2 POLYCOMB REPRESSIVE COMPLEX 2 SUBUNIT (EZH2), FORMING REPRESSIVE H3K27(ME3) MARKS. WE OBSERVE THAT IRF1 EXPRESSION IS MEDIATED BY ZEB1 DE-REPRESSION, AND OUR STUDY DEMONSTRATES HOW AIRWAY REMODELLING/FIBROSIS IS ASSOCIATED WITH A DEFECTIVE MUCOSAL ANTIVIRAL RESPONSE THROUGH ZEB1-INITIATED EPIGENETIC SILENCING. 2017 2 698 41 BROMODOMAIN CONTAINING PROTEIN 4 (BRD4) REGULATES EXPRESSION OF ITS INTERACTING COACTIVATORS IN THE INNATE RESPONSE TO RESPIRATORY SYNCYTIAL VIRUS. BROMODOMAIN-CONTAINING PROTEIN 4 PLAYS A CENTRAL ROLE IN COORDINATING THE COMPLEX EPIGENETIC COMPONENT OF THE INNATE IMMUNE RESPONSE. PREVIOUS STUDIES IMPLICATED BRD4 AS A COMPONENT OF A CHROMATIN-MODIFYING COMPLEX THAT IS DYNAMICALLY RECRUITED TO A NETWORK OF PROTECTIVE CYTOKINES BY BINDING ACTIVATED TRANSCRIPTION FACTORS, POLYMERASES, AND HISTONES TO TRIGGER THEIR RAPID EXPRESSION VIA TRANSCRIPTIONAL ELONGATION. OUR PREVIOUS STUDY EXTENDED OUR UNDERSTANDING OF THE AIRWAY EPITHELIAL BRD4 INTERACTOME BY IDENTIFYING OVER 100 FUNCTIONALLY IMPORTANT COACTIVATORS AND TRANSCRIPTION FACTORS, WHOSE ASSOCIATION IS INDUCED BY RESPIRATORY SYNCYTIAL VIRUS (RSV) INFECTION. RSV IS AN ETIOLOGICAL AGENT OF RECURRENT RESPIRATORY TRACT INFECTIONS ASSOCIATED WITH EXACERBATIONS OF CHRONIC OBSTRUCTIVE PULMONARY DISEASE. USING A HIGHLY SELECTIVE SMALL-MOLECULE BRD4 INHIBITOR (ZL0454) DEVELOPED BY US, WE EXTEND THESE FINDINGS TO IDENTIFY THE GENE REGULATORY NETWORK DEPENDENT ON BRD4 BROMODOMAIN (BD) INTERACTIONS. HUMAN SMALL AIRWAY EPITHELIAL CELLS WERE INFECTED IN THE ABSENCE OR PRESENCE OF ZL0454, AND GENE EXPRESSION PROFILING WAS PERFORMED. A HIGHLY REPRODUCIBLE DATASET WAS OBTAINED WHICH INDICATED THAT BRD4 MEDIATES BOTH ACTIVATION AND REPRESSION OF RSV-INDUCIBLE GENE REGULATORY NETWORKS CONTROLLING CYTOKINE EXPRESSION, INTERFERON (IFN) PRODUCTION, AND EXTRACELLULAR MATRIX REMODELING. INDEX GENES OF FUNCTIONALLY SIGNIFICANT CLUSTERS WERE VALIDATED INDEPENDENTLY. WE DISCOVER THAT BRD4 REGULATES THE EXPRESSION OF ITS OWN GENE DURING THE INNATE IMMUNE RESPONSE. INTERESTINGLY, BRD4 ACTIVATES THE EXPRESSION OF NFKAPPAB/RELA, A COACTIVATOR THAT BINDS TO BRD4 IN A BD-DEPENDENT MANNER. WE EXTEND THIS FINDING TO SHOW THAT BRD4 ALSO REGULATES OTHER COMPONENTS OF ITS FUNCTIONAL INTERACTOME, INCLUDING THE MEDIATOR (MED) COACTIVATOR COMPLEX AND THE SWI/SNF-RELATED, MATRIX-ASSOCIATED, ACTIN-DEPENDENT REGULATOR OF CHROMATIN (SMARC) SUBUNITS. TO PROVIDE FURTHER INSIGHT INTO MECHANISMS FOR BRD4 IN RSV EXPRESSION, WE MAPPED 7,845 RSV-INDUCIBLE TN5 TRANSPOSASE PEAKS ONTO THE BRD4-DEPENDENT GENE BODIES. THESE WERE LOCATED IN PROMOTERS AND INTRONS OF CYTOSTRUCTURAL AND EXTRACELLULAR MATRIX (ECM) FORMATION GENES. THESE DATA INDICATE THAT BRD4 MEDIATES THE DYNAMIC RESPONSE OF AIRWAY EPITHELIAL CELLS TO RNA INFECTION BY MODULATING THE EXPRESSION OF ITS COACTIVATORS, CONTROLLING THE EXPRESSION OF HOST DEFENSE MECHANISMS AND REMODELING GENES THROUGH CHANGES IN PROMOTER ACCESSIBILITY. 2021 3 5607 27 RSV-INDUCED H3K4 DEMETHYLASE KDM5B LEADS TO REGULATION OF DENDRITIC CELL-DERIVED INNATE CYTOKINES AND EXACERBATES PATHOGENESIS IN VIVO. RESPIRATORY SYNCYTIAL VIRUS (RSV) INFECTION CAN RESULT IN SEVERE DISEASE PARTIALLY DUE TO ITS ABILITY TO INTERFERE WITH THE INITIATION OF TH1 RESPONSES TARGETING THE PRODUCTION OF TYPE I INTERFERONS (IFN) AND PROMOTING A TH2 IMMUNE ENVIRONMENT. EPIGENETIC MODULATION OF GENE TRANSCRIPTION HAS BEEN SHOWN TO BE IMPORTANT IN REGULATING INFLAMMATORY PATHWAYS. RSV-INFECTED BONE MARROW-DERIVED DCS (BMDCS) UPREGULATED EXPRESSION OF KDM5B/JARID1B H3K4 DEMETHYLASE. KDM5B-SPECIFIC SIRNA INHIBITION IN BMDC LED TO A 10-FOLD INCREASE IN IFN-BETA AS WELL AS INCREASES IN IL-6 AND TNF-ALPHA COMPARED TO CONTROL-TRANSFECTED CELLS. THE GENERATION OF KDM5BFL/FL-CD11C-CRE+ MICE RECAPITULATED THE LATTER RESULTS DURING IN VITRO DC ACTIVATION SHOWING INNATE CYTOKINE MODULATION. IN VIVO, INFECTION OF KDM5BFL/FL-CD11C-CRE+ MICE WITH RSV RESULTED IN HIGHER PRODUCTION OF IFN-GAMMA AND REDUCED IL-4 AND IL-5 COMPARED TO LITTERMATE CONTROLS, WITH SIGNIFICANTLY DECREASED INFLAMMATION, IL-13, AND MUCUS PRODUCTION IN THE LUNGS. SENSITIZATION WITH RSV-INFECTED DCS INTO THE AIRWAYS OF NAIVE MICE LED TO AN EXACERBATED RESPONSE WHEN MICE WERE CHALLENGED WITH LIVE RSV INFECTION. WHEN KDM5B WAS BLOCKED IN DCS WITH SIRNA OR DCS FROM KDM5BFL/FL-CD11C-CRE MICE WERE USED, THE EXACERBATED RESPONSE WAS ABROGATED. IMPORTANTLY, HUMAN MONOCYTE-DERIVED DCS TREATED WITH A CHEMICAL INHIBITOR FOR KDM5B RESULTED IN INCREASED INNATE CYTOKINE LEVELS AS WELL AS ELICITED DECREASED TH2 CYTOKINES WHEN CO-CULTURED WITH RSV REACTIVATED CD4+ T CELLS. THESE RESULTS SUGGEST THAT KDM5B ACTS TO REPRESS TYPE I IFN AND OTHER INNATE CYTOKINES TO PROMOTE AN ALTERED IMMUNE RESPONSE FOLLOWING RSV INFECTION THAT CONTRIBUTES TO DEVELOPMENT OF CHRONIC DISEASE. 2015 4 5430 18 REGULATORS INVOLVED IN TROPHOBLAST SYNCYTIALIZATION IN THE PLACENTA OF INTRAUTERINE GROWTH RESTRICTION. PLACENTAL DYSFUNCTION REFERS TO THE INSUFFICIENCY OF PLACENTAL PERFUSION AND CHRONIC HYPOXIA DURING EARLY PREGNANCY, WHICH IMPAIRS PLACENTAL FUNCTION AND CAUSES INADEQUATE SUPPLY OF OXYGEN AND NUTRIENTS TO THE FETUS, AFFECTING FETAL DEVELOPMENT AND HEALTH. FETAL INTRAUTERINE GROWTH RESTRICTION, ONE OF THE MOST COMMON OUTCOMES OF PREGNANCY-INDUCED HYPERTENSIONS, CAN BE CAUSED BY PLACENTAL DYSFUNCTION, RESULTING FROM DEFICIENT TROPHOBLAST SYNCYTIALIZATION, INADEQUATE TROPHOBLAST INVASION AND IMPAIRED VASCULAR REMODELING. DURING PLACENTAL DEVELOPMENT, CYTOTROPHOBLASTS FUSE TO FORM A MULTINUCLEATED SYNCYTIA BARRIER, WHICH SUPPLIES OXYGEN AND NUTRIENTS TO MEET THE METABOLIC DEMANDS FOR FETAL GROWTH. A REDUCTION IN THE CELL FUSION INDEX AND THE NUMBER OF NUCLEI IN THE SYNCYTIOTROPHOBLAST ARE FOUND IN THE PLACENTAS OF PREGNANCIES COMPLICATED BY IUGR, SUGGESTING THAT THE OCCURRENCE OF IUGR MAY BE RELATED TO INADEQUATE TROPHOBLAST SYNCYTIALIZATION. DURING THE MULTIPLE PROCESSES OF TROPHOBLASTS SYNCYTIALIZATION, SPECIFIC PROTEINS AND SEVERAL SIGNALING PATHWAYS ARE INVOLVED IN COORDINATING THESE EVENTS AND REGULATING PLACENTAL FUNCTION. IN ADDITION, EPIGENETIC MODIFICATIONS, CELL METABOLISM, SENESCENCE, AND AUTOPHAGY ARE ALSO INVOLVED. STUDY FINDINGS HAVE INDICATED SEVERAL ABNORMALLY EXPRESSED SYNCYTIALIZATION-RELATED PROTEINS AND SIGNALING PATHWAYS IN THE PLACENTAS OF PREGNANCIES COMPLICATED BY IUGR, SUGGESTING THAT THESE ELEMENTS MAY PLAY A CRUCIAL ROLE IN THE OCCURRENCE OF IUGR. IN THIS REVIEW, WE DISCUSS THE REGULATORS OF TROPHOBLAST SYNCYTIALIZATION AND THEIR ABNORMAL EXPRESSION IN THE PLACENTAS OF PREGNANCIES COMPLICATED BY IUGR. 2023 5 2671 26 ETHANOL CONSUMPTION INDUCES NONSPECIFIC INFLAMMATION AND FUNCTIONAL DEFECTS IN ALVEOLAR MACROPHAGES. CHRONIC ALCOHOL DRINKING IS ASSOCIATED WITH INCREASED SUSCEPTIBILITY TO VIRAL AND BACTERIAL RESPIRATORY PATHOGENS. IN THIS STUDY, WE USE A RHESUS MACAQUE MODEL OF VOLUNTARY ETHANOL SELF-ADMINISTRATION TO STUDY THE EFFECTS OF LONG-TERM ALCOHOL DRINKING ON THE IMMUNOLOGICAL LANDSCAPE OF THE LUNG. WE REPORT A HEIGHTENED INFLAMMATORY STATE IN ALVEOLAR MACROPHAGES (AMS) OBTAINED FROM ETHANOL (ETOH)-DRINKING ANIMALS THAT IS ACCOMPANIED BY INCREASED CHROMATIN ACCESSIBILITY IN INTERGENIC REGIONS THAT REGULATE INFLAMMATORY GENES AND CONTAIN BINDING MOTIFS FOR TRANSCRIPTION FACTORS AP-1, IRF8, AND NFKB P-65. IN LINE WITH THESE TRANSCRIPTIONAL AND EPIGENETIC CHANGES AT THE BASAL STATE, AMS FROM ETOH-DRINKING ANIMALS GENERATE ELEVATED INFLAMMATORY MEDIATOR RESPONSES TO LIPOPOLYSACCHARIDES AND RESPIRATORY SYNCYTIAL VIRUS. HOWEVER, THE TRANSCRIPTIONAL ANALYSIS REVEALED AN INEFFICIENT INDUCTION OF INTERFERON-STIMULATED GENES WITH ETOH IN RESPONSE TO THE RESPIRATORY SYNCYTIAL VIRUS, SUGGESTING DISRUPTION OF ANTIMICROBIAL DEFENSES. CORRESPONDINGLY, AMS FROM ETOH-DRINKING ANIMALS EXHIBITED TRANSCRIPTIONAL SHIFTS INDICATIVE OF INCREASED OXIDATIVE STRESS AND OXIDATIVE PHOSPHORYLATION, WHICH WAS COUPLED WITH HIGHER CYTOSOLIC REACTIVE OXYGEN SPECIES AND MITOCHONDRIAL POTENTIAL. THIS HEIGHTENED OXIDATIVE STRESS STATE WAS ACCOMPANIED BY DECREASED ABILITY TO PHAGOCYTOSE BACTERIA. BULK RNA AND ASSAY FOR TRANSPOSASE-ACCESSIBLE CHROMATIN SEQUENCING DATA FURTHER REVEALED REDUCED EXPRESSION AND CHROMATIN ACCESSIBILITY OF LOCI ASSOCIATED WITH TISSUE REPAIR AND MAINTENANCE WITH CHRONIC ETOH DRINKING. SIMILARLY, ANALYSIS OF SINGLE-CELL RNA SEQUENCING DATA REVEALED SHIFTS IN CELL STATES FROM TISSUE MAINTENANCE TO INFLAMMATORY RESPONSES WITH ETOH. COLLECTIVELY, THESE DATA PROVIDE NOVEL INSIGHT INTO MECHANISMS BY WHICH CHRONIC ETOH DRINKING INCREASES SUSCEPTIBILITY TO INFECTION IN PATIENTS WITH ALCOHOL USE DISORDERS. 2022 6 5425 26 REGULATION OF MYELOPOIESIS BY THE TRANSCRIPTION FACTOR IRF8. INTERFERON REGULATORY FACTOR-8 (IRF8) IS A TRANSCRIPTION FACTOR EXPRESSED IN HEMATOPOIETIC CELLS, PARTICULARLY IN MONONUCLEAR PHAGOCYTES [MONOCYTES/MACROPHAGES AND DENDRITIC CELLS (DCS)] AND THEIR PROGENITORS. VARIOUS STUDIES HAVE DEMONSTRATED THAT IRF8 IS ESSENTIAL FOR THE DEVELOPMENT OF MONOCYTES, DCS, EOSINOPHILS, AND BASOPHILS. CONVERSELY, IRF8 SUPPRESSES THE GENERATION OF NEUTROPHILS. ACCORDINGLY, IRF8 (-/-) MICE DEVELOP IMMUNODEFICIENCY AND A CHRONIC MYELOID LEUKEMIA (CML)-LIKE DISEASE. MUTATIONS AND LOSS OF EXPRESSION OF THE HUMAN IRF8 GENE ARE ALSO ASSOCIATED WITH IMMUNODEFICIENCY AND CML, RESPECTIVELY. RECENT FINDINGS HAVE BEGUN TO REVEAL THE TRANSCRIPTION FACTOR NETWORK AND EPIGENETIC CHANGES GOVERNED BY IRF8. FOR EXAMPLE, IN MONONUCLEAR PHAGOCYTE PROGENITORS, IRF8 COOPERATES WITH PU.1 TO PROMOTE THE FORMATION OF PROMOTER-DISTAL ENHANCERS TO INDUCE MONOCYTE-RELATED GENES INCLUDING THE CRITICAL DOWNSTREAM TRANSCRIPTION FACTOR GENE KLF4. ON THE OTHER HAND, IRF8 BLOCKS C/EBPALPHA ACTIVITY TO SUPPRESS THE NEUTROPHIL DIFFERENTIATION PROGRAM. INDEED, IRF8 (-/-) MONONUCLEAR PHAGOCYTE PROGENITORS FAIL TO EFFICIENTLY GENERATE MONOCYTES AND DCS AND, INSTEAD, ABERRANTLY GIVE RISE TO NEUTROPHILS. THIS ARTICLE PROVIDES AN OVERVIEW OF RECENT ADVANCES IN OUR UNDERSTANDING OF THE ROLE OF IRF8 IN MYELOPOIESIS AND RELATED DISEASES. 2015 7 5920 46 TARGETING CHROMATIN REMODELING IN INFLAMMATION AND FIBROSIS. MUCOSAL SURFACES OF THE HUMAN BODY ARE LINED BY A CONTIGUOUS EPITHELIAL CELL SURFACE THAT FORMS A BARRIER TO AEROSOLIZED PATHOGENS. SPECIALIZED PATTERN RECOGNITION RECEPTORS DETECT THE PRESENCE OF VIRAL PATHOGENS AND INITIATE PROTECTIVE HOST RESPONSES BY TRIGGERING ACTIVATION OF THE NUCLEAR FACTOR KAPPAB (NFKAPPAB)/RELA TRANSCRIPTION FACTOR AND FORMATION OF A COMPLEX WITH THE POSITIVE TRANSCRIPTION ELONGATION FACTOR (P-TEFB)/CYCLIN-DEPENDENT KINASE (CDK)9 AND BROMODOMAIN-CONTAINING PROTEIN 4 (BRD4) EPIGENETIC READER. THE RELA.BRD4.P-TEFB COMPLEX PRODUCES ACUTE INFLAMMATION BY REGULATING TRANSCRIPTIONAL ELONGATION, WHICH PRODUCES A RAPID GENOMIC RESPONSE BY INACTIVE GENES MAINTAINED IN AN OPEN CHROMATIN CONFIGURATION ENGAGED WITH HYPOPHOSPHORYLATED RNA POLYMERASE II. WE DESCRIBE RECENT STUDIES THAT HAVE LINKED PROLONGED ACTIVATION OF THE RELA-BRD4 PATHWAY WITH THE EPITHELIAL-MESENCHYMAL TRANSITION (EMT) BY INDUCING A CORE OF EMT COREPRESSORS, STIMULATING SECRETION OF GROWTH FACTORS PROMOTING AIRWAY FIBROSIS. THE MESENCHYMAL STATE PRODUCES REWIRING OF THE KINOME AND REPROGRAMMING OF INNATE RESPONSES TOWARD INFLAMMATION. IN ADDITION, THE CORE REGULATOR ZINC FINGER E-BOX HOMEODOMAIN 1 (ZEB1) SILENCES THE EXPRESSION OF THE INTERFERON RESPONSE FACTOR 1 (IRF1), REQUIRED FOR TYPE III IFN EXPRESSION. THIS EPIGENETIC SILENCING IS MEDIATED BY THE ENHANCER OF ZESTE 2 (EZH2) HISTONE METHYLTRANSFERASE. BECAUSE OF THEIR POTENTIAL APPLICATIONS IN CANCER AND INFLAMMATION, SMALL-MOLECULE INHIBITORS OF NFKAPPAB/RELA, CDK9, BRD4, AND EZH2 HAVE BEEN THE TARGETS OF MEDICINAL CHEMISTRY EFFORTS. WE SUGGEST THAT DISRUPTION OF THE RELA.BRD4.P-TEFB PATHWAY AND EZH2 METHYLTRANSFERASE HAS IMPORTANT IMPLICATIONS FOR REVERSING FIBROSIS AND RESTORING NORMAL MUCOSAL IMMUNITY IN CHRONIC INFLAMMATORY DISEASES. 2017 8 699 22 BROMODOMAIN PROTEIN 4 IS A KEY MOLECULAR DRIVER OF TGFBETA1-INDUCED HEPATIC STELLATE CELL ACTIVATION. LIVER FIBROSIS IS CHARACTERIZED BY THE EXCESSIVE DEPOSITION OF EXTRACELLULAR MATRIX IN LIVER. CHRONIC LIVER INJURY INDUCES THE ACTIVATION OF HEPATIC STELLATE CELL (HSCS), A KEY STEP IN LIVER FIBROGENESIS. THE ACTIVATED HSC IS THE PRIMARY SOURCE OF ECM AND CONTRIBUTES SIGNIFICANTLY TO LIVER FIBROSIS. TGFBETA1 IS THE MOST POTENT PRO-FIBROTIC CYTOKINE. BROMODOMAIN PROTEIN 4 (BRD4), AN EPIGENETIC READER OF HISTONE ACETYLATION MARKS, WAS CRUCIAL FOR PROFIBROTIC GENE EXPRESSION IN HSCS. THE PRESENT STUDY AIMED TO INVESTIGATE THE ROLES OF BRD4 IN TGFBETA1-DEPENDENT HSC ACTIVATION AND LIVER FIBROSIS, FOCUSING ON TGFBETA1-INDUCED ALTERATIONS OF THE LEVELS OF THE FIBROTIC-RELATED IMPORTANT PROTEINS IN HSCS BY EMPLOYING THE HETEROZYGOUS TGFBETA1 KNOCKOUT MICE AND BRD4 KNOCKDOWN IN VIVO AND IN VITRO. RESULTS REVEALED THAT BRD4 PROTEIN LEVEL WAS SIGNIFICANTLY UPREGULATED BY TGFBETA1 AND BRD4 KNOCKDOWN REDUCED TGFBETA1-INDUCED HSC ACTIVATION AND LIVER FIBROSIS. BRD4 WAS REQUIRED FOR THE INFLUENCES OF TGFBETA1 ON PDGFBETA RECEPTOR AND ON THE PATHWAYS OF SMAD3, STAT3, AND AKT. BRD4 ALSO MEDIATED TGFBETA1-INDUCED INCREASES IN HISTONE ACETYLTRANSFERASE P300, THE PIVOTAL PRO-INFLAMMATORY NFKB P65, AND TISSUE INHIBITOR OF METALLOPROTEINASE 1 WHEREAS BRD4 REDUCED CASPASE-3 PROTEIN LEVELS IN HSCS DURING LIVER INJURY, INDEPENDENT OF TGFBETA1. FURTHER EXPERIMENTS INDICATED THE INTERACTION BETWEEN TGFBETA1-INDUCED BRD4 AND NFKB P65 IN HSCS AND IN LIVER OF TAA-INDUCED LIVER INJURY. HUMAN CIRRHOTIC LIVERS WERE DEMONSTRATED A PARALLEL INCREASE IN THE PROTEIN LEVELS OF BRD4 AND NFKB P65 IN HSCS. THIS STUDY REVEALED THAT BRD4 WAS A KEY MOLECULAR DRIVER OF TGFBETA1-INDUCED HSC ACTIVATION AND LIVER FIBROSIS. 2023 9 5054 33 PHARMACOPROTEOMICS REVEAL NOVEL PROTECTIVE ACTIVITY OF BROMODOMAIN CONTAINING 4 INHIBITORS ON VASCULAR HOMEOSTASIS IN TLR3-MEDIATED AIRWAY REMODELING. SMALL MOLECULE INHIBITORS OF THE EPIGENETIC REGULATOR BROMODOMAIN-CONTAINING PROTEIN 4 (BRD4) ARE POTENTIAL THERAPEUTICS FOR VIRAL AND ALLERGEN-INDUCED AIRWAY REMODELING. A LIMITATION OF THEIR PRECLINICAL ADVANCEMENT IS THE LACK OF DETAILED UNDERSTANDING OF MECHANISMS OF ACTION AND BIOMARKERS OF EFFECT. WE REPORT A SYSTEMS-LEVEL PHARMACOPROTEOMICS IN A STANDARDIZED MURINE MODEL OF TOLL-LIKE RECEPTOR TLR3-NFKAPPAB/RELA INNATE INFLAMMATION IN THE ABSENCE OR PRESENCE OF A HIGHLY SELECTIVE BRD4 INHIBITOR (ZL0454) OR NONSELECTIVE BROMODOMAIN AND EXTRATERMINAL DOMAIN INHIBITOR (JQ1). PROTEOMICS OF BRONCHOALVEOLAR LAVAGE FLUID (BALF) SECRETOME AND EXOSOMAL PROTEINS FROM THIS MURINE MODEL REVEALED INCREASED, SELECTIVE, CAPILLARY LEAK ASSOCIATED WITH PERICYTE-MYOFIBROBLAST TRANSITION, A PHENOMENON BLOCKED BY BRD4 INHIBITORS. BALF PROTEOMICS ALSO SUGGESTED THAT ZL0454 BETTER REDUCED THE VASCULAR LEAKAGE AND EXTRACELLULAR MATRIX DEPOSITION THAN JQ1. A SIGNIFICANT SUBSET OF INFLAMMATION-MEDIATED REMODELING FACTORS WAS ALSO IDENTIFIED IN A MOUSE MODEL OF IDIOPATHIC PULMONARY FIBROSIS PRODUCED BY BLEOMYCIN. BALF EXOSOME ANALYSIS INDICATED THAT BRD4 INHIBITORS REDUCED THE INDUCTION OF EXOSOMES ENRICHED IN COAGULATION FACTORS WHOSE PRESENCE CORRELATED WITH INTERSTITIAL FIBRIN DEPOSITION. FINALLY, BALF SAMPLES FROM HUMANS WITH SEVERE ASTHMA DEMONSTRATED SIMILAR UPREGULATIONS OF ORM2, APCS, SPARCL1, FGA, AND FN1, SUGGESTING THEIR POTENTIAL AS BIOMARKERS FOR EARLY DETECTION OF AIRWAY REMODELING AND/OR MONITORING OF THERAPY RESPONSE. SIGNIFICANCE: REPETITIVE AND CHRONIC VIRAL UPPER RESPIRATORY TRACT INFECTIONS TRIGGER TOLL-LIKE RECEPTOR (TLR)3-NFKAPPAB/RELA MEDIATED AIRWAY REMODELING WHICH IS LINKED TO A PROGRESSIVE DECLINE IN PULMONARY FUNCTION IN PATIENTS WITH ASTHMA AND CHRONIC OBSTRUCTIVE PULMONARY DISEASE. SMALL MOLECULE INHIBITORS OF THE EPIGENETIC REGULATOR BROMODOMAIN-CONTAINING PROTEIN 4 (BRD4) ARE POTENTIAL THERAPEUTICS FOR VIRAL AND ALLERGEN-INDUCED AIRWAY REMODELING. A LIMITATION OF THEIR PRECLINICAL ADVANCEMENT IS THE LACK OF DETAILED UNDERSTANDING OF MECHANISMS OF ACTION AND BIOMARKERS OF EFFECT. OUR STUDY REVEALED THAT THE ACTIVATION OF (TLR)3-NFKAPPAB/RELA PATHWAY IN THE LUNG INDUCED AN ELEVATION IN COAGULATION, COMPLEMENT, AND PLATELET FACTORS, INDICATING THE INCREASED VASCULAR LEAK DURING AIRWAY REMODELING. THE MECHANISM OF VASCULAR LEAKAGE WAS CHRONIC INFLAMMATION-INDUCED PERICYTE-MYOFIBROBLAST TRANSITION, WHICH WAS BLOCKED BY BRD4 INHIBITORS. FINALLY, PROTEOMICS ANALYSIS OF THE BRONCHOALVEOLAR LAVAGE FLUID SAMPLES FROM HUMANS WITH SEVERE ASTHMA DEMONSTRATED SIMILAR FINDINGS THAT WE OBSERVED IN THE ANIMAL MODEL. 2019 10 4506 28 MRTF-A MEDIATES LPS-INDUCED PRO-INFLAMMATORY TRANSCRIPTION BY INTERACTING WITH THE COMPASS COMPLEX. CHRONIC INFLAMMATION UNDERSCORES THE PATHOGENESIS OF A RANGE OF HUMAN DISEASES. LIPOPOLYSACCHARIDE (LPS) ELICITS STRONG PRO-INFLAMMATORY RESPONSES IN MACROPHAGES THROUGH THE TRANSCRIPTION FACTOR NF-KAPPAB. THE EPIGENETIC MECHANISM UNDERLYING LPS-INDUCED PRO-INFLAMMATORY TRANSCRIPTION IS NOT FULLY UNDERSTOOD. HEREIN, WE DESCRIBE A ROLE FOR MYOCARDIN-RELATED TRANSCRIPTION FACTOR A (MRTF-A, ALSO KNOWN AS MKL1) IN THIS PROCESS. MRTF-A OVEREXPRESSION ENHANCED NF-KAPPAB-DEPENDENT PRO-INFLAMMATORY TRANSCRIPTION, WHEREAS MRTF-A SILENCING INHIBITED THIS PROCESS. MRTF-A DEFICIENCY ALSO REDUCED THE SYNTHESIS OF PRO-INFLAMMATORY MEDIATORS IN A MOUSE MODEL OF COLITIS. LPS PROMOTED THE RECRUITMENT OF MRTF-A TO THE PROMOTERS OF PRO-INFLAMMATORY GENES IN AN NF-KAPPAB-DEPENDENT MANNER. RECIPROCALLY, MRTF-A INFLUENCED THE NUCLEAR ENRICHMENT AND TARGET BINDING OF NF-KAPPAB. MECHANISTICALLY, MRTF-A WAS NECESSARY FOR THE ACCUMULATION OF ACTIVE HISTONE MODIFICATIONS ON NF-KAPPAB TARGET PROMOTERS BY COMMUNICATING WITH THE HISTONE H3K4 METHYLTRANSFERASE COMPLEX (COMPASS). SILENCING OF INDIVIDUAL MEMBERS OF COMPASS, INCLUDING ASH2, WDR5 AND SET1 (ALSO KNOWN AS SETD1A), DOWNREGULATED THE PRODUCTION OF PRO-INFLAMMATORY MEDIATORS AND IMPAIRED THE NF-KAPPAB KINETICS. IN SUMMARY, OUR WORK HAS UNCOVERED A PREVIOUSLY UNKNOWN FUNCTION FOR MRTF-A AND PROVIDED INSIGHTS INTO THE RATIONALIZED DEVELOPMENT OF ANTI-INFLAMMATORY THERAPEUTIC STRATEGIES. 2014 11 6687 20 VALIDATION OF THE EPIGENETIC READER BROMODOMAIN-CONTAINING PROTEIN 4 (BRD4) AS A THERAPEUTIC TARGET FOR TREATMENT OF AIRWAY REMODELING. STRUCTURAL REMODELING IS CENTRAL TO THE INITIATION AND PROGRESSION OF MANY CHRONIC LUNG DISEASES, REPRESENTING AN IMPORTANT UNMET NEED. WE EXAMINE THE EVIDENCE SUPPORTING BROMODOMAIN-CONTAINING PROTEIN 4 (BRD4) AS A VALIDATED BIOLOGICAL TARGET FOR TREATMENT OF AIRWAY REMODELING. IN EPITHELIAL CELLS AND FIBROBLASTS, BRD4 SERVES AS A SCAFFOLD FOR CHROMATIN REMODELING COMPLEXES IN ACTIVE SUPER-ENHANCERS. IN RESPONSE TO INFLAMMATORY STIMULI, BRD4 IS REPOSITIONED TO INNATE AND MESENCHYMAL GENES ACTIVATING THEIR PRODUCTION. PROOF-OF-CONCEPT STUDIES SHOW PROMISING BENEFIT OF SELECTIVE BRD4 INHIBITORS IN DISRUPTING EPITHELIAL MESENCHYMAL TRANSITION AND MYOFIBROBLAST TRANSITION IN DIVERSE MODELS OF LUNG INJURY. RECENT IDENTIFICATION OF BIOMARKERS OF BRD4 PROVIDES A BASIS FOR FURTHER DRUG DEVELOPMENT FOR APPLICATION IN VIRAL-INDUCED AIRWAY INFLAMMATION, COPD AND INTERSTITIAL LUNG DISEASES. 2020 12 729 28 CANCER ANGIOGENESIS INDUCED BY KAPOSI SARCOMA-ASSOCIATED HERPESVIRUS IS MEDIATED BY EZH2. EZH2 IS A COMPONENT OF THE EPIGENETIC REGULATOR PRC2 THAT SUPPRESSES GENE EXPRESSION. ELEVATED EXPRESSION OF EZH2 IS COMMON IN HUMAN CANCERS AND IS ASSOCIATED WITH TUMOR PROGRESSION AND POOR PROGNOSIS. IN THIS STUDY, WE SHOW THAT EZH2 ELEVATION IS ASSOCIATED WITH EPIGENETIC MODIFICATIONS OF KAPOSI SARCOMA-ASSOCIATED HERPESVIRUS (KSHV), AN ONCOGENIC VIRUS THAT PROMOTES THE DEVELOPMENT OF KAPOSI SARCOMA AND OTHER MALIGNANCIES THAT OCCUR IN PATIENTS WITH CHRONIC HIV INFECTIONS. KSHV INDUCTION OF EZH2 EXPRESSION WAS ESSENTIAL FOR KSHV-INDUCED ANGIOGENESIS. HIGH EXPRESSION OF EZH2 WAS OBSERVED IN KAPOSI SARCOMA TUMORS. IN CELL CULTURE, LATENT KSHV INFECTION UPREGULATED THE EXPRESSION OF EZH2 IN HUMAN ENDOTHELIAL CELLS THROUGH THE EXPRESSION OF VFLIP AND LANA, TWO KSHV-LATENT GENES THAT ACTIVATE THE NF-KAPPAB PATHWAY. KSHV-MEDIATED UPREGULATION OF EZH2 WAS REQUIRED FOR THE INDUCTION OF EPHRIN-B2, AN ESSENTIAL PROANGIOGENIC FACTOR THAT DRIVES ENDOTHELIAL CELL TUBULE FORMATION. TAKEN TOGETHER, OUR FINDINGS INDICATE THAT KSHV REGULATES THE HOST EPIGENETIC MODIFIER EZH2 TO PROMOTE ANGIOGENESIS. 2012 13 5301 24 PROTEIN PHOSPHATASE 2A CATALYTIC SUBUNIT ALPHA PLAYS A MYD88-DEPENDENT, CENTRAL ROLE IN THE GENE-SPECIFIC REGULATION OF ENDOTOXIN TOLERANCE. MYD88, THE INTRACELLULAR ADAPTOR OF MOST TLRS, MEDIATES EITHER PROINFLAMMATORY OR IMMUNOSUPPRESSIVE SIGNALING THAT CONTRIBUTES TO CHRONIC INFLAMMATION-ASSOCIATED DISEASES. ALTHOUGH GENE-SPECIFIC CHROMATIN MODIFICATIONS REGULATE INFLAMMATION, THE ROLE OF MYD88 SIGNALING IN ESTABLISHING SUCH EPIGENETIC LANDSCAPES UNDER DIFFERENT INFLAMMATORY STATES REMAINS ELUSIVE. USING QUANTITATIVE PROTEOMICS TO ENUMERATE THE INFLAMMATION-PHENOTYPIC CONSTITUENTS OF THE MYD88 INTERACTOME, WE FOUND THAT IN ENDOTOXIN-TOLERANT MACROPHAGES, PROTEIN PHOSPHATASE 2A CATALYTIC SUBUNIT ALPHA (PP2AC) ENHANCES ITS ASSOCIATION WITH MYD88 AND IS CONSTITUTIVELY ACTIVATED. KNOCKDOWN OF PP2AC PREVENTS SUPPRESSION OF PROINFLAMMATORY GENES AND RESISTANCE TO APOPTOSIS. THROUGH SITE-SPECIFIC DEPHOSPHORYLATION, CONSTITUTIVELY ACTIVE PP2AC DISRUPTS THE SIGNAL-PROMOTING TLR4-MYD88 COMPLEX AND BROADLY SUPPRESSES THE ACTIVITIES OF MULTIPLE PROINFLAMMATORY/PROAPOPTOTIC PATHWAYS AS WELL, SHIFTING PROINFLAMMATORY MYD88 SIGNALING TO A PROSURVIVAL MODE. CONSTITUTIVELY ACTIVE PP2AC TRANSLOCATED WITH MYD88 INTO THE NUCLEI OF TOLERANT MACROPHAGES ESTABLISHES THE IMMUNOSUPPRESSIVE PATTERN OF CHROMATIN MODIFICATIONS AND REPRESSES CHROMATIN REMODELING TO SELECTIVELY SILENCE PROINFLAMMATORY GENES, COORDINATING THE MYD88-DEPENDENT INFLAMMATION CONTROL AT BOTH SIGNALING AND EPIGENETIC LEVELS UNDER ENDOTOXIN-TOLERANT CONDITIONS. 2013 14 3373 30 HISTONE MODULATION BLOCKS TREG-INDUCED FOXP3 BINDING TO THE IL-2 PROMOTER OF VIRUS-SPECIFIC CD8(+) T CELLS FROM FELINE IMMUNODEFICIENCY VIRUS-INFECTED CATS. CD8(+) T CELLS ARE CRITICAL FOR CONTROLLING HIV INFECTION. DURING THE CHRONIC PHASE OF LENTIVIRAL INFECTION, CD8(+) T CELLS LOSE THEIR PROLIFERATIVE CAPACITY AND EXHIBIT IMPAIRED ANTIVIRAL FUNCTION. THIS LOSS OF CD8(+) T CELL FUNCTION IS DUE, IN PART, TO CD4(+)CD25(+) T REGULATORY (TREG) CELL-MEDIATED SUPPRESSION. OUR RESEARCH GROUP HAS DEMONSTRATED THAT LENTIVIRUS-ACTIVATED CD4(+)CD25(+) TREG CELLS INDUCE THE REPRESSIVE TRANSCRIPTION FACTOR FORKHEAD BOX P3 (FOXP3) IN AUTOLOGOUS CD8(+) T CELLS FOLLOWING CO-CULTURE. WE HAVE RECENTLY REPORTED THAT TREG-INDUCED FOXP3 BINDS THE INTERLEUKIN-2 (IL-2), INTERFERON-GAMMA (IFN- GAMMA), AND TUMOR NECROSIS FACTOR-ALPHA (TNF-ALPHA) PROMOTERS IN VIRUS-SPECIFIC CD8(+) T CELLS. THESE DATA SUGGEST AN IMPORTANT ROLE OF FOXP3-MEDIATED CD8(+) T CELL DYSFUNCTION IN LENTIVIRAL INFECTION. TO ELUCIDATE THE MECHANISM OF THIS SUPPRESSION, WE PREVIOUSLY REPORTED THAT DECREASED METHYLATION FACILITATES FOXP3 BINDING IN MITOGEN-ACTIVATED CD8(+) T CELLS FROM FELINE IMMUNODEFICIENCY VIRUS (FIV)-INFECTED CATS. WE DEMONSTRATED THE REDUCED BINDING OF FOXP3 TO THE IL-2 PROMOTER BY INCREASING METHYLATION OF CD8(+) T CELLS. IN THE STUDIES PRESENTED HERE, WE ASK IF ANOTHER FORM OF EPIGENETIC MODULATION MIGHT ALLEVIATE FOXP3-MEDIATED SUPPRESSION IN CD8(+) T CELLS. WE HYPOTHESIZED THAT DECREASING HISTONE ACETYLATION IN VIRUS-SPECIFIC CD8(+) T CELLS WOULD DECREASE TREG-INDUCED FOXP3 BINDING TO THE IL-2 PROMOTER. INDEED, USING ANACARDIC ACID (AA), A KNOWN HISTONE ACETYL TRANSFERASE (HAT) INHIBITOR, WE DEMONSTRATE A REDUCTION IN FOXP3 BINDING TO THE IL-2 PROMOTER IN VIRUS-SPECIFIC CD8(+) T CELLS CO-CULTURED WITH AUTOLOGOUS TREG CELLS. THESE DATA IDENTIFY A NOVEL MECHANISM OF FOXP3-MEDIATED CD8(+) T CELL DYSFUNCTION DURING LENTIVIRAL INFECTION. 2018 15 589 23 BET BROMODOMAIN INHIBITORS SUPPRESS INFLAMMATORY ACTIVATION OF GINGIVAL FIBROBLASTS AND EPITHELIAL CELLS FROM PERIODONTITIS PATIENTS. BET BROMODOMAIN PROTEINS ARE IMPORTANT EPIGENETIC REGULATORS OF GENE EXPRESSION THAT BIND ACETYLATED HISTONE TAILS AND REGULATE THE FORMATION OF ACETYLATION-DEPENDENT CHROMATIN COMPLEXES. BET INHIBITORS SUPPRESS INFLAMMATORY RESPONSES IN MULTIPLE CELL TYPES AND ANIMAL MODELS, AND PROTECT AGAINST BONE LOSS IN EXPERIMENTAL PERIODONTITIS IN MICE. HERE, WE ANALYZED THE ROLE OF BET PROTEINS IN INFLAMMATORY ACTIVATION OF GINGIVAL FIBROBLASTS (GFS) AND GINGIVAL EPITHELIAL CELLS (GECS). WE SHOW THAT THE BET INHIBITORS I-BET151 AND JQ1 SIGNIFICANTLY REDUCED EXPRESSION AND/OR PRODUCTION OF DISTINCT, BUT OVERLAPPING, PROFILES OF CYTOKINE-INDUCIBLE MEDIATORS OF INFLAMMATION AND BONE RESORPTION IN GFS FROM HEALTHY DONORS (IL6, IL8, IL1B, CCL2, CCL5, COX2, AND MMP3) AND THE GEC LINE TIGK (IL6, IL8, IL1B, CXCL10, MMP9) WITHOUT AFFECTING CELL VIABILITY. ACTIVATION OF MITOGEN-ACTIVATED PROTEIN KINASE AND NUCLEAR FACTOR-KAPPAB PATHWAYS WAS UNAFFECTED BY I-BET151, AS WAS THE HISTONE ACETYLATION STATUS, AND NEW PROTEIN SYNTHESIS WAS NOT REQUIRED FOR THE ANTI-INFLAMMATORY EFFECTS OF BET INHIBITION. I-BET151 AND JQ1 ALSO SUPPRESSED EXPRESSION OF INFLAMMATORY CYTOKINES, CHEMOKINES, AND OSTEOCLASTOGENIC MEDIATORS IN GFS AND TIGKS INFECTED WITH THE KEY PERIODONTAL PATHOGEN PORPHYROMONAS GINGIVALIS. NOTABLY, P. GINGIVALIS INTERNALIZATION AND INTRACELLULAR SURVIVAL IN GFS AND TIGKS REMAINED UNAFFECTED BY BET INHIBITORS. FINALLY, INHIBITION OF BET PROTEINS SIGNIFICANTLY REDUCED P. GINGIVALIS-INDUCED INFLAMMATORY MEDIATOR EXPRESSION IN GECS AND GFS FROM PATIENTS WITH PERIODONTITIS. OUR RESULTS DEMONSTRATE THAT BET INHIBITORS MAY BLOCK THE EXCESSIVE INFLAMMATORY MEDIATOR PRODUCTION BY RESIDENT CELLS OF THE GINGIVAL TISSUE AND IDENTIFY THE BET FAMILY OF EPIGENETIC READER PROTEINS AS A POTENTIAL THERAPEUTIC TARGET IN THE TREATMENT OF PERIODONTAL DISEASE. 2019 16 4582 24 N-TERMINAL BET BROMODOMAIN INHIBITORS DISRUPT A BRD4-P65 INTERACTION AND REDUCE INDUCIBLE NITRIC OXIDE SYNTHASE TRANSCRIPTION IN PANCREATIC BETA-CELLS. CHRONIC INFLAMMATION OF PANCREATIC ISLETS IS A KEY DRIVER OF BETA-CELL DAMAGE THAT CAN LEAD TO AUTOREACTIVITY AND THE EVENTUAL ONSET OF AUTOIMMUNE DIABETES (T1D). IN THE ISLET, ELEVATED LEVELS OF PROINFLAMMATORY CYTOKINES INDUCE THE TRANSCRIPTION OF THE INDUCIBLE NITRIC OXIDE SYNTHASE (INOS) GENE, NOS2, ULTIMATELY RESULTING IN INCREASED NITRIC OXIDE (NO). EXCESSIVE OR PROLONGED EXPOSURE TO NO CAUSES BETA-CELL DYSFUNCTION AND FAILURE ASSOCIATED WITH DEFECTS IN MITOCHONDRIAL RESPIRATION. RECENT STUDIES SHOWED THAT INHIBITION OF THE BROMODOMAIN AND EXTRATERMINAL DOMAIN (BET) FAMILY OF PROTEINS, A DRUGGABLE CLASS OF EPIGENETIC READER PROTEINS, PREVENTS THE ONSET AND PROGRESSION OF T1D IN THE NON-OBESE DIABETIC MOUSE MODEL. WE HYPOTHESIZED THAT BET PROTEINS CO-ACTIVATE TRANSCRIPTION OF CYTOKINE-INDUCED INFLAMMATORY GENE TARGETS IN BETA-CELLS AND THAT SELECTIVE, CHEMOTHERAPEUTIC INHIBITION OF BET BROMODOMAINS COULD REDUCE SUCH TRANSCRIPTION. HERE, WE INVESTIGATED THE ABILITY OF BET BROMODOMAIN SMALL MOLECULE INHIBITORS TO REDUCE THE BETA-CELL RESPONSE TO THE PROINFLAMMATORY CYTOKINE INTERLEUKIN 1 BETA (IL-1BETA). BET BROMODOMAIN INHIBITION ATTENUATED IL-1BETA-INDUCED TRANSCRIPTION OF THE INFLAMMATORY MEDIATOR NOS2 AND CONSEQUENT INOS PROTEIN AND NO PRODUCTION. REDUCED NOS2 TRANSCRIPTION IS CONSISTENT WITH INHIBITION OF NF-KAPPAB FACILITATED BY DISRUPTING THE INTERACTION OF A SINGLE BET FAMILY MEMBER, BRD4, WITH THE NF-KAPPAB SUBUNIT, P65. USING RECENTLY REPORTED SELECTIVE INHIBITORS OF THE FIRST AND SECOND BET BROMODOMAINS, INHIBITION OF ONLY THE FIRST BROMODOMAIN WAS NECESSARY TO REDUCE THE INTERACTION OF BRD4 WITH P65 IN BETA-CELLS. MOREOVER, INHIBITION OF THE FIRST BROMODOMAIN WAS SUFFICIENT TO MITIGATE IL-1BETA-DRIVEN DECREASES IN MITOCHONDRIAL OXYGEN CONSUMPTION RATES AND BETA-CELL VIABILITY. BY IDENTIFYING A ROLE FOR THE INTERACTION BETWEEN BRD4 AND P65 IN CONTROLLING THE RESPONSE OF BETA-CELLS TO PROINFLAMMATORY CYTOKINES, WE PROVIDE MECHANISTIC INFORMATION ON HOW BET BROMODOMAIN INHIBITION CAN DECREASE INFLAMMATION. THESE STUDIES ALSO SUPPORT THE POTENTIAL THERAPEUTIC APPLICATION OF MORE SELECTIVE BET BROMODOMAIN INHIBITORS IN ATTENUATING BETA-CELL INFLAMMATION. 2022 17 1667 26 DOWNREGULATION OF PCAF BY MIR-181A/B PROVIDES FEEDBACK REGULATION TO TNF-ALPHA-INDUCED TRANSCRIPTION OF PROINFLAMMATORY GENES IN LIVER EPITHELIAL CELLS. ABERRANT CELLULAR RESPONSES TO PROINFLAMMATORY CYTOKINES, SUCH AS TNF-ALPHA, ARE PATHOGENIC FEATURES IN MOST CHRONIC INFLAMMATORY DISEASES. A VARIETY OF EXTRACELLULAR AND INTRACELLULAR FEEDBACK PATHWAYS HAS EVOLVED TO PREVENT AN INAPPROPRIATE CELLULAR REACTION TO THESE PROINFLAMMATORY CYTOKINES. IN THIS STUDY, WE REPORT THAT TNF-ALPHA TREATMENT OF HUMAN AND MOUSE CHOLANGIOCYTES AND HEPATOCYTES DOWNREGULATED EXPRESSION OF P300/CBP-ASSOCIATED FACTOR (PCAF), A COACTIVATOR AND AN ACETYLTRANSFERASE THAT PROMOTES HISTONE ACETYLATION AND GENE TRANSCRIPTION. OF THESE UPREGULATED MICRORNAS IN TNF-ALPHA-TREATED CELLS, MIR-181A/B (MIR-181A AND MIR-181B) SUPPRESSED TRANSLATION OF PCAF MRNA. FUNCTIONAL MANIPULATION OF MIR-181A/B CAUSED RECIPROCAL ALTERATIONS IN PCAF PROTEIN EXPRESSION IN CULTURED CHOLANGIOCYTES AND HEPATOCYTES. INHIBITION OF MIR-181A/B FUNCTION WITH ANTI-MIRS BLOCKED TNF-ALPHA-INDUCED SUPPRESSION OF PCAF EXPRESSION. PROMOTER RECRUITMENT OF PCAF WAS SHOWN TO BE ASSOCIATED WITH TNF-ALPHA-INDUCED TRANSCRIPTION OF INFLAMMATORY GENES. INTRIGUINGLY, PRETREATMENT OF CELLS WITH TNF-ALPHA INHIBITED TRANSCRIPTION OF INFLAMMATORY GENES IN RESPONSE TO SUBSEQUENT TNF-ALPHA STIMULATION. OVEREXPRESSION OF PCAF OR INHIBITION OF MIR-181A/B FUNCTION WITH ANTI-MIRS ATTENUATED THE INHIBITORY EFFECTS OF TNF-ALPHA PRETREATMENT ON EPITHELIAL INFLAMMATORY RESPONSE TO SUBSEQUENT TNF-ALPHA STIMULATION. DOWNREGULATION OF PCAF AND THE INHIBITORY EFFECTS OF TNF-ALPHA PRETREATMENT ON LIVER EPITHELIAL INFLAMMATORY RESPONSE WERE FURTHER CONFIRMED IN A MOUSE MODEL OF TNF-ALPHA I.P. INJECTION. THESE DATA SUGGEST THAT PCAF IS A TARGET FOR MIR-181A/B, AND DOWNREGULATION OF PCAF BY TNF-ALPHA PROVIDES NEGATIVE FEEDBACK REGULATION TO INFLAMMATORY REACTIONS IN LIVER EPITHELIAL CELLS, A PROCESS THAT MAY BE RELEVANT TO THE EPIGENETIC FINE-TUNING OF EPITHELIAL INFLAMMATORY PROCESSES IN GENERAL. 2012 18 3357 23 HISTONE H3 LYSINE 9 DI-METHYLATION AS AN EPIGENETIC SIGNATURE OF THE INTERFERON RESPONSE. EFFECTIVE ANTIVIRAL IMMUNITY DEPENDS ON THE ABILITY OF INFECTED CELLS OR CELLS TRIGGERED WITH VIRUS-DERIVED NUCLEIC ACIDS TO PRODUCE TYPE I INTERFERON (IFN), WHICH ACTIVATES TRANSCRIPTION OF NUMEROUS ANTIVIRAL GENES. HOWEVER, DISPROPORTIONATELY STRONG OR CHRONIC IFN EXPRESSION IS A COMMON CAUSE OF INFLAMMATORY AND AUTOIMMUNE DISEASES. WE DESCRIBE AN EPIGENETIC MECHANISM THAT DETERMINES CELL TYPE-SPECIFIC DIFFERENCES IN IFN AND IFN-STIMULATED GENE (ISG) EXPRESSION IN RESPONSE TO EXOGENOUS SIGNALS. WE IDENTIFY DI-METHYLATION OF HISTONE H3 AT LYSINE 9 (H3K9ME2) AS A SUPPRESSOR OF IFN AND IFN-INDUCIBLE ANTIVIRAL GENE EXPRESSION. WE SHOW THAT LEVELS OF H3K9ME2 AT IFN AND ISG CORRELATE INVERSELY WITH THE SCOPE AND AMPLITUDE OF IFN AND ISG EXPRESSION IN FIBROBLASTS AND DENDRITIC CELLS. ACCORDINGLY, GENETIC ABLATION OR PHARMACOLOGICAL INACTIVATION OF LYSINE METHYLTRANSFERASE G9A, WHICH IS ESSENTIAL FOR THE GENERATION OF H3K9ME2, RESULTED IN PHENOTYPIC CONVERSION OF FIBROBLASTS INTO HIGHLY POTENT IFN-PRODUCING CELLS AND RENDERED THESE CELLS RESISTANT TO PATHOGENIC RNA VIRUSES. IN SUMMARY, OUR STUDIES IMPLICATE H3K9ME2 AND ENZYMES CONTROLLING ITS ABUNDANCE AS KEY REGULATORS OF INNATE ANTIVIRAL IMMUNITY. 2012 19 1862 25 EMERGENCE OF FIBROBLASTS WITH A PROINFLAMMATORY EPIGENETICALLY ALTERED PHENOTYPE IN SEVERE HYPOXIC PULMONARY HYPERTENSION. PERSISTENT ACCUMULATION OF MONOCYTES/MACROPHAGES IN THE PULMONARY ARTERY ADVENTITIAL/PERIVASCULAR AREAS OF ANIMALS AND HUMANS WITH PULMONARY HYPERTENSION HAS BEEN DOCUMENTED. THE CELLULAR MECHANISMS CONTRIBUTING TO CHRONIC INFLAMMATORY RESPONSES REMAIN UNCLEAR. WE HYPOTHESIZED THAT PERIVASCULAR INFLAMMATION IS PERPETUATED BY ACTIVATED ADVENTITIAL FIBROBLASTS, WHICH, THROUGH SUSTAINED PRODUCTION OF PROINFLAMMATORY CYTOKINES/CHEMOKINES AND ADHESION MOLECULES, INDUCE ACCUMULATION, RETENTION, AND ACTIVATION OF MONOCYTES/MACROPHAGES. WE FURTHER HYPOTHESIZED THAT THIS PROINFLAMMATORY PHENOTYPE IS THE RESULT OF THE ABNORMAL ACTIVITY OF HISTONE-MODIFYING ENZYMES, SPECIFICALLY, CLASS I HISTONE DEACETYLASES (HDACS). PULMONARY ADVENTITIAL FIBROBLASTS FROM CHRONICALLY HYPOXIC HYPERTENSIVE CALVES (TERMED PH-FIBS) EXPRESSED A CONSTITUTIVE AND PERSISTENT PROINFLAMMATORY PHENOTYPE DEFINED BY HIGH EXPRESSION OF IL-1BETA, IL-6, CCL2(MCP-1), CXCL12(SDF-1), CCL5(RANTES), CCR7, CXCR4, GM-CSF, CD40, CD40L, AND VCAM-1. THE PROINFLAMMATORY PHENOTYPE OF PH-FIBS WAS ASSOCIATED WITH EPIGENETIC ALTERATIONS AS DEMONSTRATED BY INCREASED ACTIVITY OF HDACS AND THE FINDINGS THAT CLASS I HDAC INHIBITORS MARKEDLY DECREASED CYTOKINE/CHEMOKINE MRNA EXPRESSION LEVELS IN THESE CELLS. PH-FIBS INDUCED INCREASED ADHESION OF THP-1 MONOCYTES AND PRODUCED SOLUBLE FACTORS THAT INDUCED INCREASED MIGRATION OF THP-1 AND MURINE BONE MARROW-DERIVED MACROPHAGES AS WELL AS ACTIVATED MONOCYTES/MACROPHAGES TO EXPRESS PROINFLAMMATORY CYTOKINES AND PROFIBROGENIC MEDIATORS (TIMP1 AND TYPE I COLLAGEN) AT THE TRANSCRIPTIONAL LEVEL. CLASS I HDAC INHIBITORS MARKEDLY REDUCED THE ABILITY OF PH-FIBS TO INDUCE MONOCYTE MIGRATION AND PROINFLAMMATORY ACTIVATION. THE EMERGENCE OF A DISTINCT ADVENTITIAL FIBROBLAST POPULATION WITH AN EPIGENETICALLY ALTERED PROINFLAMMATORY PHENOTYPE CAPABLE OF RECRUITING, RETAINING, AND ACTIVATING MONOCYTES/MACROPHAGES CHARACTERIZES PULMONARY HYPERTENSION-ASSOCIATED VASCULAR REMODELING AND THUS COULD CONTRIBUTE SIGNIFICANTLY TO CHRONIC INFLAMMATORY PROCESSES IN THE PULMONARY ARTERY WALL. 2011 20 3781 22 INTERFERON SIGNATURE IN PATIENTS WITH STAT1 GAIN-OF-FUNCTION MUTATION IS EPIGENETICALLY DETERMINED. STAT1 GAIN-OF-FUNCTION (GOF) VARIANTS LEAD TO DEFECTIVE TH17 CELL DEVELOPMENT AND CHRONIC MUCOCUTANEOUS CANDIDIASIS (CMC), BUT FREQUENTLY ALSO TO AUTOIMMUNITY. STIMULATION OF CELLS WITH STAT1 INDUCING CYTOKINES LIKE INTERFERONS (IFN) RESULT IN HYPERPHOSPHORYLATION AND DELAYED DEPHOSPHORYLATION OF GOF STAT1. HOWEVER, THE MECHANISM HOW THE DELAYED DEPHOSPHORYLATION EXACTLY CAUSES THE INCREASED EXPRESSION OF STAT1-DEPENDENT GENES, AND HOW THE INTRACELLULAR SIGNAL TRANSDUCTION FROM CYTOKINE RECEPTORS IS AFFECTED, REMAINS UNKNOWN. IN THIS STUDY WE SHOW THAT THE CIRCULATING LEVELS OF IFN-ALPHA WERE NOT PERSISTENTLY ELEVATED IN STAT1 GOF PATIENTS. NEVERTHELESS, THE EXPRESSION OF INTERFERON SIGNATURE GENES WAS EVIDENT EVEN IN THE PATIENT WITH LOW OR UNDETECTABLE SERUM IFN-ALPHA LEVELS. CHROMATIN IMMUNOPRECIPITATION (CHIP) EXPERIMENTS REVEALED THAT THE ACTIVE CHROMATIN MARK TRIMETHYLATION OF LYSINE 4 OF HISTONE 3 (H3K4ME3), WAS SIGNIFICANTLY ENRICHED IN AREAS ASSOCIATED WITH INTERFERON-STIMULATED GENES IN STAT1 GOF CELLS IN COMPARISON TO CELLS FROM HEALTHY DONORS. THIS SUGGESTS THAT THE CHROMATIN BINDING OF GOF STAT1 VARIANT PROMOTES EPIGENETIC CHANGES COMPATIBLE WITH HIGHER GENE EXPRESSION AND ELEVATED REACTIVITY TO TYPE I INTERFERONS, AND POSSIBLY PREDISPOSES FOR INTERFERON-RELATED AUTOIMMUNITY. THE RESULTS ALSO SUGGEST THAT EPIGENETIC REWIRING MAY BE RESPONSIBLE FOR TREATMENT FAILURE OF JANUS KINASE 1/2 (JAK1/2) INHIBITORS IN CERTAIN PATIENTS. 2019