1 730 112 CANCER CELLS RESISTANT TO IMMUNE CHECKPOINT BLOCKADE ACQUIRE INTERFERON-ASSOCIATED EPIGENETIC MEMORY TO SUSTAIN T CELL DYSFUNCTION. PROLONGED INTERFERON (IFN) SIGNALING IN CANCER CELLS CAN PROMOTE RESISTANCE TO IMMUNE CHECKPOINT BLOCKADE (ICB). HOW CANCER CELLS RETAIN EFFECTS OF PROLONGED IFN STIMULATION TO COORDINATE RESISTANCE IS UNCLEAR. WE SHOW THAT, ACROSS HUMAN AND/OR MOUSE TUMORS, IMMUNE DYSFUNCTION IS ASSOCIATED WITH CANCER CELLS ACQUIRING EPIGENETIC FEATURES OF INFLAMMATORY MEMORY. HERE, INFLAMMATORY MEMORY DOMAINS, MANY OF WHICH ARE INITIATED BY CHRONIC IFN-GAMMA, ARE MAINTAINED BY SIGNAL TRANSDUCER AND ACTIVATOR OF TRANSCRIPTION (STAT)1 AND IFN REGULATORY FACTOR (IRF)3 AND LINK HISTONE 3 LYSINE 4 MONOMETHYLATION (H3K4ME1)-MARKED CHROMATIN ACCESSIBILITY TO INCREASED EXPRESSION OF A SUBSET OF IFN-STIMULATED GENES (ISGS). THESE ISGS INCLUDE THE RNA SENSOR OAS1 THAT AMPLIFIES TYPE I IFN (IFN-I) AND IMMUNE INHIBITORY GENES. ABROGATING CANCER CELL IFN-I SIGNALING RESTORES ANTI-PROGRAMMED CELL DEATH PROTEIN 1 (PD1) RESPONSE BY INCREASING IFN-GAMMA IN IMMUNE CELLS, PROMOTING DENDRITIC CELL AND CD8(+) T CELL INTERACTIONS, AND EXPANDING T CELLS TOWARD EFFECTOR-LIKE STATES RATHER THAN EXHAUSTED STATES. THUS, CANCER CELLS ACQUIRE INFLAMMATORY MEMORY TO AUGMENT A SUBSET OF ISGS THAT PROMOTE AND PREDICT IFN-DRIVEN IMMUNE DYSFUNCTION. 2023 2 5429 26 REGULATION OF TYPE I INTERFERON RESPONSES. TYPE I INTERFERONS (IFNS) ACTIVATE INTRACELLULAR ANTIMICROBIAL PROGRAMMES AND INFLUENCE THE DEVELOPMENT OF INNATE AND ADAPTIVE IMMUNE RESPONSES. CANONICAL TYPE I IFN SIGNALLING ACTIVATES THE JANUS KINASE (JAK)-SIGNAL TRANSDUCER AND ACTIVATOR OF TRANSCRIPTION (STAT) PATHWAY, LEADING TO TRANSCRIPTION OF IFN-STIMULATED GENES (ISGS). HOST, PATHOGEN AND ENVIRONMENTAL FACTORS REGULATE THE RESPONSES OF CELLS TO THIS SIGNALLING PATHWAY AND THUS CALIBRATE HOST DEFENCES WHILE LIMITING TISSUE DAMAGE AND PREVENTING AUTOIMMUNITY. HERE, WE SUMMARIZE THE SIGNALLING AND EPIGENETIC MECHANISMS THAT REGULATE TYPE I IFN-INDUCED STAT ACTIVATION AND ISG TRANSCRIPTION AND TRANSLATION. THESE REGULATORY MECHANISMS DETERMINE THE BIOLOGICAL OUTCOMES OF TYPE I IFN RESPONSES AND WHETHER PATHOGENS ARE CLEARED EFFECTIVELY OR CHRONIC INFECTION OR AUTOIMMUNE DISEASE ENSUES. 2014 3 3779 35 INTERFERON ALPHA INDUCES MULTIPLE CELLULAR PROTEINS THAT COORDINATELY SUPPRESS HEPADNAVIRAL COVALENTLY CLOSED CIRCULAR DNA TRANSCRIPTION. COVALENTLY CLOSED CIRCULAR DNA (CCCDNA) OF HEPADNAVIRUSES EXISTS AS AN EPISOMAL MINICHROMOSOME IN THE NUCLEUS OF AN INFECTED HEPATOCYTE AND SERVES AS THE TEMPLATE FOR THE TRANSCRIPTION OF VIRAL MRNAS. IT HAD BEEN DEMONSTRATED BY OTHERS AND US THAT INTERFERON ALPHA (IFN-ALPHA) TREATMENT OF HEPATOCYTES INDUCED A PROLONGED SUPPRESSION OF HUMAN AND DUCK HEPATITIS B VIRUS CCCDNA TRANSCRIPTION, WHICH IS ASSOCIATED WITH THE REDUCTION OF CCCDNA-ASSOCIATED HISTONE MODIFICATIONS SPECIFYING ACTIVE TRANSCRIPTION (H3K9(AC) OR H3K27(AC)), BUT NOT THE HISTONE MODIFICATIONS MARKING CONSTITUTIVE (H3K9(ME3)) OR FACULTATIVE (H3K27(ME3)) HETEROCHROMATIN FORMATION. IN OUR EFFORTS TO IDENTIFY IFN-INDUCED CELLULAR PROTEINS THAT MEDIATE THE SUPPRESSION OF CCCDNA TRANSCRIPTION BY THE CYTOKINE, WE FOUND THAT DOWNREGULATING THE EXPRESSION OF SIGNAL TRANSDUCER AND ACTIVATOR OF TRANSCRIPTION 1 (STAT1), STRUCTURAL MAINTENANCE OF CHROMOSOMES FLEXIBLE HINGE DOMAIN CONTAINING 1 (SMCHD1), OR PROMYELOCYTIC LEUKEMIA (PML) PROTEIN INCREASED BASAL LEVEL OF CCCDNA TRANSCRIPTION ACTIVITY AND PARTIALLY ATTENUATED IFN-ALPHA SUPPRESSION OF CCCDNA TRANSCRIPTION. IN CONTRAST, ECTOPIC EXPRESSION OF STAT1, SMCHD1, OR PML SIGNIFICANTLY REDUCED CCCDNA TRANSCRIPTION ACTIVITY. SMCHD1 IS A NONCANONICAL SMC FAMILY PROTEIN AND IMPLICATED IN EPIGENETIC SILENCING OF GENE EXPRESSION. PML IS A COMPONENT OF NUCLEAR DOMAIN 10 (ND10) AND IS INVOLVED IN SUPPRESSING THE REPLICATION OF MANY DNA VIRUSES. MECHANISTIC ANALYSES DEMONSTRATED THAT STAT1, SMCHD1, AND PML WERE RECRUITED TO CCCDNA MINICHROMOSOMES AND PHENOCOPIED THE IFN-ALPHA-INDUCED POSTTRANSLATIONAL MODIFICATIONS OF CCCDNA-ASSOCIATED HISTONES. WE THUS CONCLUDE THAT STAT1, SMCHD1, AND PML MAY PARTLY MEDIATE THE SUPPRESSIVE EFFECT OF IFN-ALPHA ON HEPADNAVIRAL CCCDNA TRANSCRIPTION.IMPORTANCE PEGYLATED IFN-ALPHA IS THE ONLY THERAPEUTIC REGIMEN THAT CAN INDUCE A FUNCTIONAL CURE OF CHRONIC HEPATITIS B IN A SMALL, BUT SIGNIFICANT, FRACTION OF TREATED PATIENTS. UNDERSTANDING THE MECHANISMS UNDERLYING THE ANTIVIRAL FUNCTIONS OF IFN-ALPHA IN HEPADNAVIRAL INFECTION MAY REVEAL MOLECULAR TARGETS FOR DEVELOPMENT OF NOVEL ANTIVIRAL AGENTS TO IMPROVE THE THERAPEUTIC EFFICACY OF IFN-ALPHA. BY A LOSS-OF-FUNCTION GENETIC SCREENING OF INDIVIDUAL IFN-STIMULATED GENES (ISGS) ON HEPADNAVIRAL MRNAS TRANSCRIBED FROM CCCDNA, WE FOUND THAT DOWNREGULATING THE EXPRESSION OF STAT1, SMCHD1, OR PML SIGNIFICANTLY INCREASED THE LEVEL OF VIRAL RNAS WITHOUT ALTERING THE LEVEL OF CCCDNA. MECHANISTIC ANALYSES INDICATED THAT THOSE CELLULAR PROTEINS ARE RECRUITED TO CCCDNA MINICHROMOSOMES AND INDUCE THE POSTTRANSLATIONAL MODIFICATIONS OF CCCDNA-ASSOCIATED HISTONES SIMILAR TO THOSE INDUCED BY IFN-ALPHA TREATMENT. WE HAVE THUS IDENTIFIED THREE IFN-ALPHA-INDUCED CELLULAR PROTEINS THAT SUPPRESS CCCDNA TRANSCRIPTION AND MAY PARTLY MEDIATE IFN-ALPHA SILENCING OF HEPADNAVIRAL CCCDNA TRANSCRIPTION. 2020 4 3357 34 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 5 2401 33 EPIGENETIC REPROGRAMMING PROMOTES THE ANTIVIRAL ACTION OF IFNALPHA IN HBV-INFECTED CELLS. CHRONIC HEPATITIS B VIRUS (HBV) INFECTIONS REMAIN A HEALTH BURDEN AFFECTING ~250 MILLION PEOPLE WORLDWIDE. THUS FAR, AVAILABLE INTERFERON-ALPHA (IFNALPHA)-BASED THERAPIES HAVE SHOWN UNSATISFACTORY CURE RATES, AND ALTERNATIVE THERAPEUTIC MOLECULES ARE STILL REQUIRED. HOWEVER, THEIR DEVELOPMENT HAS BEEN HAMPERED BECAUSE ACCESSIBLE CELL MODELS SUPPORTING RELEVANT HBV REPLICATION AND APPROPRIATE ANTIVIRAL ACTIVITY ARE LACKING. STRATEGIES THAT REVERSE EPIGENETIC ALTERATIONS OFFER A UNIQUE OPPORTUNITY FOR CELL REPROGRAMMING, WHICH IS VALUABLE FOR RESTORING ALTERED CELLULAR FUNCTIONS IN HUMAN CELL LINES. THIS WORK AIMED TO INVESTIGATE THE FEASIBILITY OF CONVERTING HEPG2 CELLS THAT STABLY OVEREXPRESS THE HBV ENTRY RECEPTOR (SODIUM/TAUROCHOLATE COTRANSPORTING POLYPEPTIDE, NTCP) TOWARD IFNALPHA-RESPONSIVE CELLS USING EPIGENETIC REPROGRAMMING. HEREIN, WE SHOWED THAT AN EPIGENETIC REGIMEN WITH NON-CYTOTOXIC DOSES OF THE DEMETHYLATING COMPOUND 5-AZACYTIDINE RESTORED THE ANTI-HBV ACTION OF IFNALPHA IN EPIGENETICALLY REPROGRAMMED HEPG2-NTCP-C4 CELLS, NAMED REP-HEPG2-NTCP CELLS. THUS, A SIGNIFICANT INHIBITION IN HBV DNA LEVELS WAS MEASURED IN REP-HEPG2-NTCP CELLS AFTER IFNALPHA TREATMENT. THIS INHIBITORY EFFECT WAS ASSOCIATED WITH THE ENHANCEMENT OF IFNALPHA-MEDIATED INDUCTION OF CRITICAL INTERFERON-STIMULATED GENES (ISGS), WHICH WAS LIMITED IN NON-REPROGRAMMED CELLS. IN PARTICULAR, OUR DATA INDICATED THAT RE-EXPRESSION OF 2'-5'-OLIGOADENYLATE SYNTHETASE 1 (OAS1) AND INTERFERON REGULATORY FACTOR 9 (IRF9) WAS THE RESULT OF AN EPIGENETICALLY DRIVEN UNMASKING OF THESE GENES IN REPROGRAMMED CELLS. AT LAST, WE EVALUATED THE THERAPEUTIC POTENTIAL OF THE IFN ANALOG CDM-3008 IN REP-HEPG2-NTCP CELLS AND DEMONSTRATED THE EFFICIENCY OF THIS CHEMICAL COMPOUND IN TRIGGERING ISG INDUCTION AND HBV INHIBITION. IN SUMMARY, THIS STUDY SHOWS THAT EPIGENETIC REPROGRAMMING PROMOTES THE IFNALPHA RESPONSE IN HBV-INFECTED CELLS AND IS POTENTIALLY ATTRACTIVE FOR CELL-BASED EXPERIMENTAL SCREENING OF IFN-LIKE COMPOUNDS. 2021 6 170 37 ABNORMALITIES OF THE TYPE I INTERFERON SIGNALING PATHWAY IN LUPUS AUTOIMMUNITY. TYPE I INTERFERONS (IFNS), MOSTLY IFNALPHA AND IFNBETA, AND THE TYPE I IFN SIGNATURE ARE IMPORTANT IN THE PATHOGENESIS OF SYSTEMIC LUPUS ERYTHEMATOSUS (SLE), AN AUTOIMMUNE CHRONIC CONDITION LINKED TO INFLAMMATION. BOTH IFNALPHA AND IFNBETA TRIGGER A SIGNALING CASCADE THAT, THROUGH THE ACTIVATION OF JAK1, TYK2, STAT1 AND STAT2, INITIATES GENE TRANSCRIPTION OF IFN STIMULATED GENES (ISGS). NOTEWORTHY, OTHER STAT FAMILY MEMBERS AND IFN RESPONSIVE FACTORS (IRFS) CAN ALSO CONTRIBUTE TO THE ACTIVATION OF THE IFN RESPONSE. ABERRANT TYPE I IFN SIGNALING, THEREFORE, CAN EXACERBATE SLE BY DEREGULATED HOMEOSTASIS LEADING TO UNNECESSARY PERSISTENCE OF THE BIOLOGICAL EFFECTS OF TYPE I IFNS. THE ETIOPATHOGENESIS OF SLE IS PARTIALLY KNOWN AND CONSIDERED MULTIFACTORIAL. FAMILY-BASED AND GENOME WIDE ASSOCIATION STUDIES (GWAS) HAVE IDENTIFIED GENETIC AND TRANSCRIPTIONAL ABNORMALITIES IN KEY MOLECULES DIRECTLY INVOLVED IN THE TYPE I IFN SIGNALING PATHWAY, NAMELY TYK2, STAT1 AND STAT4, AND IRF5. GAIN-OF-FUNCTION MUTATIONS THAT HEIGHTEN IFNALPHA/BETA PRODUCTION, WHICH IN TURN MAINTAINS TYPE I IFN SIGNALING, ARE FOUND IN OTHER PATHOLOGIES LIKE THE INTERFERONOPATHIES. HOWEVER, THE DISTINCTIVE CHARACTERISTICS HAVE YET TO BE DETERMINED. SIGNALING MOLECULES ACTIVATED IN RESPONSE TO TYPE I IFNS ARE UPREGULATED IN IMMUNE CELL SUBSETS AND AFFECTED TISSUES OF SLE PATIENTS. MOREOVER, TYPE I IFNS INDUCE CHROMATIN REMODELING LEADING TO A STATE PERMISSIVE TO TRANSCRIPTION, AND SLE PATIENTS HAVE INCREASED GLOBAL AND GENE-SPECIFIC EPIGENETIC MODIFICATIONS, SUCH AS HYPOMETHYLATION OF DNA AND HISTONE ACETYLATION. EPIGENOME WIDE ASSOCIATION STUDIES (EWAS) HIGHLIGHT IMPORTANT DIFFERENCES BETWEEN SLE PATIENTS AND HEALTHY CONTROLS IN INTERFERON STIMULATED GENES (ISGS). THE COMBINATION OF ENVIRONMENTAL AND GENETIC FACTORS MAY STIMULATE TYPE I IFN SIGNALING TRANSIENTLY AND PRODUCE LONG-LASTING DETRIMENTAL EFFECTS THROUGH EPIGENETIC ALTERATIONS. SUBSTANTIAL EVIDENCE FOR THE PATHOGENIC ROLE OF TYPE I IFNS IN SLE ADVOCATES THE CLINICAL USE OF NEUTRALIZING ANTI-TYPE I IFN RECEPTOR ANTIBODIES AS A THERAPEUTIC STRATEGY, WITH CLINICAL STUDIES ALREADY SHOWING PROMISING RESULTS. CURRENT AND FUTURE CLINICAL TRIALS WILL DETERMINE WHETHER DRUGS TARGETING MOLECULES OF THE TYPE I IFN SIGNALING PATHWAY, LIKE NON-SELECTIVE JAK INHIBITORS OR SPECIFIC TYK2 INHIBITORS, MAY BENEFIT PEOPLE LIVING WITH LUPUS. 2021 7 5510 32 RIBAVIRIN RESTORES IFNALPHA RESPONSIVENESS IN HCV-INFECTED LIVERS BY EPIGENETIC REMODELLING AT INTERFERON STIMULATED GENES. OBJECTIVES: CAVEATS IN THE UNDERSTANDING OF RIBAVIRIN (RBV) MECHANISMS OF ACTION HAS SOMEHOW PREVENTED THE DEVELOPMENT OF BETTER ANALOGUES ABLE TO FURTHER IMPROVE ITS THERAPEUTIC CONTRIBUTION IN INTERFERON (IFN)-BASED AND DIRECT ANTIVIRAL AGENT-BASED REGIMENS FOR CHRONIC HCV OR OTHER INDICATIONS. HERE, WE DESCRIBE A NEW MECHANISM BY WHICH RBV MODULATES IFN-STIMULATED GENES (ISGS) AND CONTRIBUTES TO RESTORE HEPATIC IMMUNE RESPONSIVENESS. DESIGN: RBV EFFECT ON ISG EXPRESSION WAS MONITORED IN VITRO AND IN VIVO, THAT IS, IN NON-TRANSFORMED HEPATOCYTES AND IN THE LIVER OF RBV MONO-TREATED PATIENTS, RESPECTIVELY. MODULATION OF HISTONE MODIFICATIONS AND RECRUITMENT OF HISTONE-MODIFYING ENZYMES AT TARGET PROMOTERS WAS ANALYSED BY CHROMATIN IMMUNOPRECIPITATION IN RBV-TREATED PRIMARY HUMAN HEPATOCYTES AND IN PATIENTS' LIVER BIOPSIES. RESULTS: RBV DECREASES THE MRNA LEVELS OF SEVERAL ABNORMALLY PREACTIVATED ISGS IN PATIENTS WITH HCV, WHO ARE NON-RESPONDERS TO IFN THERAPY. RBV INCREASES G9A HISTONE METHYLTRANSFERASE RECRUITMENT AND HISTONE-H3 LYSINE-9 DIMETHYLATION/TRIMETHYLATION AT SELECTED ISG PROMOTERS IN VITRO AND IN VIVO. G9A PHARMACOLOGICAL BLOCKADE ABOLISHES RBV-INDUCED ISG DOWNREGULATION AND SEVERELY IMPAIRS RBV ABILITY TO POTENTIATE IFN ANTIVIRAL ACTION AND INDUCTION OF ISGS FOLLOWING HCV INFECTION OF PRIMARY HUMAN HEPATOCYTES. CONCLUSIONS: RBV-INDUCED EPIGENETIC CHANGES, LEADING TO DECREASED ISG EXPRESSION, RESTORE AN IFN-RESPONSIVE HEPATIC ENVIRONMENT IN PATIENTS WITH HCV, WHICH MAY ALSO PROVE USEFUL IN IFN-FREE REGIMENS. 2016 8 3249 34 HEPATITIS B VIRUS HIJACKS CTHRC1 TO EVADE HOST IMMUNITY AND MAINTAIN REPLICATION. HEPATITIS B VIRUS (HBV) INFECTION CAUSES ACUTE AND CHRONIC LIVER DISEASES, BUT IS NOT DIRECTLY CYTOPATHIC. LIVER INJURY RESULTS FROM REPEATED ATTEMPTS OF THE CELLULAR IMMUNE RESPONSE SYSTEM TO CONTROL THE VIRAL INFECTION. HERE, WE INVESTIGATE THE ROLES OF CELLULAR FACTORS AND SIGNALING PATHWAYS INVOLVED IN THE REGULATION OF HBV REPLICATION TO REVEAL THE MECHANISM UNDERLYING HBV INFECTION AND PATHOGENESIS. WE SHOW THAT COLLAGEN TRIPLE HELIX REPEAT CONTAINING 1 (CTHRC1) EXPRESSION IS ELEVATED IN HBV-INFECTED PATIENTS AND IN HBV-TRANSFECTED CELLS THROUGH EPIGENETIC MODIFICATION AND TRANSCRIPTIONAL REGULATION. CTHRC1 FACILITATES HBV REPLICATION IN CULTURED CELLS AND BALB/C MICE BY ACTIVATING THE PKCALPHA/ERK/JNK/C-JUN CASCADE TO REPRESS THE IFN/JAK/STAT PATHWAY. HBV-ACTIVATED CTHRC1 DOWNREGULATES THE ACTIVITY OF TYPE I INTERFERON (IFN), THE PRODUCTION OF IFN-STIMULATED GENES (ISGS), AND THE PHOSPHORYLATION OF SIGNAL TRANSDUCER AND ACTIVATOR OF TRANSCRIPTION 1/2 (STAT1/2), WHEREAS IT UPREGULATES THE PHOSPHORYLATION AND UBIQUITINATION OF TYPE I IFN RECEPTORS (IFNARALPHA/BETA). THUS, OUR RESULTS SHOW THAT HBV USES A NOVEL MECHANISM TO HIJACK CELLULAR FACTORS AND SIGNAL CASCADES IN ORDER TO EVADE HOST ANTIVIRAL IMMUNITY AND MAINTAIN PERSISTENT INFECTION. WE ALSO DEMONSTRATE THAT CTHRC1 HAS A NOVEL ROLE IN VIRAL INFECTION. 2015 9 4239 23 METHYLATION PROFILE OF HEPATITIS B VIRUS IS NOT INFLUENCED BY INTERFERON ALPHA IN HUMAN LIVER CANCER CELLS. INTERFERON (IFN) ALPHA IS USED FOR THE TREATMENT OF CHRONIC HEPATITIS B VIRUS (HBV) INFECTION, BUT THE MOLECULAR MECHANISMS UNDERLYING ITS ANTIVIRAL EFFECT HAVE NOT BEEN FULLY ELUCIDATED. EPIGENETIC MODIFICATIONS REGULATE THE TRANSCRIPTIONAL ACTIVITY OF COVALENTLY CLOSED CIRCULAR DNA (CCCDNA) IN CELLS WITH CHRONIC HBV INFECTION. IFN?ALPHA HAS BEEN SHOWN TO MODIFY CCCDNA?BOUND HISTONES, BUT IT IS NOT KNOWN WHETHER THE ANTI?HBV EFFECT OF IFN?ALPHA INVOLVES METHYLATION OF CCCDNA. THE PRESENT STUDY AIMED TO DETERMINE WHETHER IFN?ALPHA INDUCED METHYLATION OF HBV CCCDNA IN A CELL?BASED MODEL IN WHICH HEPG2 CELLS WERE DIRECTLY INFECTED WITH WILD?TYPE HBV VIRIONS. METHYLATION STATUS OF HBV CCCDNA WAS ASSESSED USING GLOBAL DNA METHYLATION ELISA ASSAY, METHYLATION?SPECIFIC PCR AND BISULFITE SEQUENCING. IFN?ALPHA SUPPRESSED HBV DNA AND RNA TRANSCRIPTS, BUT METHYLATION PROFILES WERE SIMILAR BETWEEN THE CONTROL AND IFN?ALPHA TREATED GROUPS. CHROMATIN IMMUNOPRECIPITATION RESULTS REVEALED BINDING OF DNA METHYLTRANSFERASES (DNMT) 3A AND DNMT3B TO HBV CCCDNA AND TREATMENT WITH IFN?ALPHA SUPPRESSED THE RECRUITMENT OF DNMT3B TO CCCDNA. TAKEN TOGETHER, THESE RESULTS SUGGEST THAT IFN?ALPHA DOES NOT INDUCE METHYLATION OF HBV CCCDNA. THEREFORE, IT WAS CONCLUDED THAT METHYLATION IS UNLIKELY TO CONTRIBUTE TO THE ANTI?HBV EFFECT OF IFN?ALPHA IN HEPG2 CELLS, AND THAT ALTERNATIVE MECHANISMS NEED TO BE SOUGHT TO ENHANCE CCCDNA METHYLATION AS A NOVEL THERAPY AGAINST HBV. 2021 10 6605 32 TYPE 1 DIABETES: INTERFERONS AND THE AFTERMATH OF PANCREATIC BETA-CELL ENTEROVIRAL INFECTION. ENTEROVIRUSES (EVS) HAVE LONG BEEN IMPLICATED IN THE PATHOGENESIS OF TYPE 1 DIABETES (T1D), AND ACCUMULATING EVIDENCE HAS ASSOCIATED VIRUS-INDUCED AUTOIMMUNITY WITH THE LOSS OF PANCREATIC BETA CELLS IN T1D. INFLAMMATORY CYTOKINES INCLUDING INTERFERONS (IFN) FORM A PRIMARY LINE OF DEFENCE AGAINST VIRAL INFECTIONS, AND THEIR CHRONIC ELEVATION IS A HALLMARK FEATURE OF MANY AUTOIMMUNE DISEASES. IFNS PLAY A KEY ROLE IN ACTIVATING AND REGULATING INNATE AND ADAPTIVE IMMUNE RESPONSES, AND TO DO SO THEY MODULATE THE EXPRESSION OF NETWORKS OF GENES AND TRANSCRIPTION FACTORS KNOWN GENERICALLY AS IFN STIMULATED GENES (ISGS). ISGS IN TURN MODULATE CRITICAL CELLULAR PROCESSES RANGING FROM CELLULAR METABOLISM AND GROWTH REGULATION TO ENDOPLASMIC RETICULUM (ER) STRESS AND APOPTOSIS. MORE RECENT STUDIES HAVE REVEALED THAT IFNS ALSO MODULATE GENE EXPRESSION AT AN EPIGENETIC AS WELL AS POST-TRANSCRIPTIONAL AND POST-TRANSLATIONAL LEVELS. AS SUCH, IFNS FORM A KEY LINK CONNECTING THE VARIOUS GENETIC, ENVIRONMENTAL AND IMMUNOLOGICAL FACTORS INVOLVED IN THE INITIATION AND PROGRESSION OF T1D. THEREFORE, GAINING AN IMPROVED UNDERSTANDING OF THE MECHANISMS BY WHICH IFNS MODULATE BETA CELL FUNCTION AND SURVIVAL IS CRUCIAL IN EXPLAINING THE PATHOGENESIS OF VIRALLY-INDUCED T1D. THIS SHOULD PROVIDE THE MEANS TO PREVENT, DECELERATE OR EVEN REVERSE BETA CELL IMPAIRMENT. 2020 11 4241 27 METHYLATION REGULATION OF ANTIVIRAL HOST FACTORS, INTERFERON STIMULATED GENES (ISGS) AND T-CELL RESPONSES ASSOCIATED WITH NATURAL HIV CONTROL. GWAS, IMMUNE ANALYSES AND BIOMARKER SCREENINGS HAVE IDENTIFIED HOST FACTORS ASSOCIATED WITH IN VIVO HIV-1 CONTROL. HOWEVER, THERE IS A GAP IN THE KNOWLEDGE ABOUT THE MECHANISMS THAT REGULATE THE EXPRESSION OF SUCH HOST FACTORS. HERE, WE AIMED TO ASSESS DNA METHYLATION IMPACT ON HOST GENOME IN NATURAL HIV-1 CONTROL. TO THIS END, WHOLE DNA METHYLOME IN 70 UNTREATED HIV-1 INFECTED INDIVIDUALS WITH EITHER HIGH (>50,000 HIV-1-RNA COPIES/ML, N = 29) OR LOW (<10,000 HIV-1-RNA COPIES/ML, N = 41) PLASMA VIRAL LOAD (PVL) LEVELS WERE COMPARED AND IDENTIFIED 2,649 DIFFERENTIALLY METHYLATED POSITIONS (DMPS). OF THESE, A CLASSIFICATION RANDOM FOREST MODEL SELECTED 55 DMPS THAT CORRELATED WITH VIROLOGIC (PVL AND PROVIRAL LEVELS) AND HIV-1 SPECIFIC ADAPTIVE IMMUNITY PARAMETERS (IFNG-T CELL RESPONSES AND NEUTRALIZING ANTIBODIES CAPACITY). THEN, CLUSTER AND FUNCTIONAL ANALYSES IDENTIFIED TWO DMP CLUSTERS: CLUSTER 1 CONTAINED HYPO-METHYLATED GENES INVOLVED IN ANTIVIRAL AND INTERFERON RESPONSE (E.G. PARP9, MX1, AND USP18) IN INDIVIDUALS WITH HIGH VIRAL LOADS WHILE IN CLUSTER 2, GENES RELATED TO T FOLLICULAR HELPER CELL (TFH) COMMITMENT (E.G. CXCR5 AND TCF7) WERE HYPER-METHYLATED IN THE SAME GROUP OF INDIVIDUALS WITH UNCONTROLLED INFECTION. FOR SELECTED GENES, MRNA LEVELS NEGATIVELY CORRELATED WITH DNA METHYLATION, CONFIRMING AN EPIGENETIC REGULATION OF GENE EXPRESSION. FURTHER, THESE GENE EXPRESSION SIGNATURES WERE ALSO CONFIRMED IN EARLY AND CHRONIC STAGES OF INFECTION, INCLUDING UNTREATED, CART TREATED AND ELITE CONTROLLERS HIV-1 INFECTED INDIVIDUALS (N = 37). THESE DATA PROVIDE THE FIRST EVIDENCE THAT HOST GENES CRITICALLY INVOLVED IN IMMUNE CONTROL OF THE VIRUS ARE UNDER METHYLATION REGULATION IN HIV-1 INFECTION. THESE INSIGHTS MAY OFFER NEW OPPORTUNITIES TO IDENTIFY NOVEL MECHANISMS OF IN VIVO VIRUS CONTROL AND MAY PROVE CRUCIAL FOR THE DEVELOPMENT OF FUTURE THERAPEUTIC INTERVENTIONS AIMED AT HIV-1 CURE. 2020 12 5547 27 ROLE OF EPIGENETIC MODIFICATION IN INTERFERON TREATMENT OF HEPATITIS B VIRUS INFECTION. HUMAN HEPATITIS B VIRUS (HBV) IS A SMALL, ENVELOPED DNA VIRUS THAT CAUSES ACUTE AND CHRONIC HEPATITIS. CHRONIC HEPATITIS B (CHB) IS ASSOCIATED WITH HEPATOCELLULAR CARCINOMA PATHOGENESIS. INTERFERONS (IFNS) HAVE BEEN USED FOR THE TREATMENT OF CHB FOR A LONG TIME, WITH ADVANTAGES INCLUDING LESS TREATMENT DURATION AND SUSTAINED VIROLOGICAL RESPONSE. PRESENTLY, VARIOUS EVIDENCE SUGGESTS THAT EPIGENETIC MODIFICATION OF THE VIRAL COVALENTLY CLOSED CIRCULAR DNA (CCCDNA) AND THE HOST GENOME IS CRUCIAL FOR THE REGULATION OF VIRAL ACTIVITY. THIS MODIFICATION INCLUDES HISTONE ACETYLATION, DNA METHYLATION, N6-METHYLADENOSINE, AND NON-CODING RNA MODIFICATION. IFN TREATMENT FOR CHB CAN STIMULATE MULTIPLE IFN-STIMULATED GENES FOR INHIBITING VIRUS REPLICATION. IFNS CAN ALSO AFFECT THE HBV LIFE CYCLE THROUGH EPIGENETIC MODULATION. IN THIS REVIEW, WE SUMMARIZED THE DIFFERENT MECHANISMS THROUGH WHICH IFN-ALPHA INHIBITS HBV REPLICATION, INCLUDING EPIGENETIC REGULATION. MOREOVER, THE MECHANISMS UNDERLYING IFN ACTIVITY ARE DISCUSSED, WHICH INDICATED ITS POTENTIAL AS A NOVEL TREATMENT FOR CHB. IT IS PROPOSED THAT EPIGENETIC CHANGES SUCH AS HISTONE ACETYLATION, DNA METHYLATION, M6A METHYLATION COULD BE THE TARGETS OF IFN, WHICH MAY OFFER A NOVEL APPROACH TO HBV TREATMENT. 2022 13 3781 33 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 14 3806 26 INTRACELLULAR INTERFERON SIGNALLING PATHWAYS AS POTENTIAL REGULATORS OF COVALENTLY CLOSED CIRCULAR DNA IN THE TREATMENT OF CHRONIC HEPATITIS B. INFECTION WITH THE HEPATITIS B VIRUS (HBV) IS STILL A MAJOR GLOBAL HEALTH THREAT AS 250 MILLION PEOPLE WORLDWIDE CONTINUE TO BE CHRONICALLY INFECTED WITH THE VIRUS. WHILE PATIENTS MAY BE TREATED WITH NUCLEOSIDE/NUCLEOTIDE ANALOGUES, THIS ONLY SUPPRESSES HBV TITRE TO SUB-DETECTION LEVELS WITHOUT ELIMINATING THE PERSISTENT HBV COVALENTLY CLOSED CIRCULAR DNA (CCCDNA) GENOME. AS A RESULT, HBV INFECTION CANNOT BE CURED, AND THE VIRUS REACTIVATES WHEN CONDITIONS ARE FAVORABLE. INTERFERONS (IFNS) ARE CYTOKINES KNOWN TO INDUCE POWERFUL ANTIVIRAL MECHANISMS THAT CLEAR VIRUSES FROM INFECTED CELLS. THEY HAVE BEEN SHOWN TO INDUCE CCCDNA CLEARANCE, BUT THEIR USE IN THE TREATMENT OF HBV INFECTION IS LIMITED AS HBV-TARGETING IMMUNE CELLS ARE EXHAUSTED AND HBV HAS EVOLVED MULTIPLE MECHANISMS TO EVADE AND SUPPRESS IFN SIGNALLING. THUS, TO FULLY UTILIZE IFN-MEDIATED INTRACELLULAR MECHANISMS TO EFFECTIVELY ELIMINATE HBV, INSTEAD OF DIRECT IFN ADMINISTRATION, NOVEL STRATEGIES TO SUSTAIN IFN-MEDIATED ANTI-CCCDNA AND ANTIVIRAL MECHANISMS NEED TO BE DEVELOPED. THIS REVIEW WILL CONSOLIDATE WHAT IS KNOWN ABOUT HOW IFNS ACT TO ACHIEVE ITS INTRACELLULAR ANTIVIRAL EFFECTS AND HIGHLIGHT THE CRITICAL INTERFERON-STIMULATED GENE TARGETS AND EFFECTOR MECHANISMS WITH POTENT ANTI-CCCDNA FUNCTIONS. THESE INCLUDE CCCDNA DEGRADATION BY APOBECS AND CCCDNA SILENCING AND TRANSCRIPTION REPRESSION BY EPIGENETIC MODIFICATIONS. IN ADDITION, THE MECHANISMS THAT HBV EMPLOYS TO DISRUPT IFN SIGNALLING WILL BE DISCUSSED. DRUGS THAT HAVE BEEN DEVELOPED OR ARE IN THE PIPELINE FOR COMPONENTS OF THE IFN SIGNALLING PATHWAY AND HBV TARGETS THAT DETRACT IFN SIGNALLING MECHANISMS WILL ALSO BE IDENTIFIED AND DISCUSSED FOR UTILITY IN THE TREATMENT OF HBV INFECTIONS. TOGETHER, THESE WILL PROVIDE USEFUL INSIGHTS INTO DESIGN STRATEGIES THAT SPECIFICALLY TARGET CCCDNA FOR THE ERADICATION OF HBV. 2021 15 5715 32 SIRT3 RESTRICTS HEPATITIS B VIRUS TRANSCRIPTION AND REPLICATION THROUGH EPIGENETIC REGULATION OF COVALENTLY CLOSED CIRCULAR DNA INVOLVING SUPPRESSOR OF VARIEGATION 3-9 HOMOLOG 1 AND SET DOMAIN CONTAINING 1A HISTONE METHYLTRANSFERASES. HEPATITIS B VIRUS (HBV) INFECTION REMAINS A MAJOR HEALTH PROBLEM WORLDWIDE. MAINTENANCE OF THE COVALENTLY CLOSED CIRCULAR DNA (CCCDNA), WHICH SERVES AS A TEMPLATE FOR HBV RNA TRANSCRIPTION, IS RESPONSIBLE FOR THE FAILURE OF ERADICATING CHRONIC HBV DURING CURRENT ANTIVIRAL THERAPY. CCCDNA IS ASSEMBLED WITH CELLULAR HISTONE PROTEINS INTO CHROMATIN, BUT LITTLE IS KNOWN ABOUT THE REGULATION OF HBV CHROMATIN BY HISTONE POSTTRANSLATIONAL MODIFICATIONS. IN THIS STUDY, WE IDENTIFIED SILENT MATING TYPE INFORMATION REGULATION 2 HOMOLOG 3 (SIRT3) AS A HOST FACTOR RESTRICTING HBV TRANSCRIPTION AND REPLICATION BY SCREENING SEVEN MEMBERS OF THE SIRTUIN FAMILY, WHICH IS THE CLASS III HISTONE DEACETYLASE. ECTOPIC SIRT3 EXPRESSION SIGNIFICANTLY REDUCED TOTAL HBV RNAS, 3.5-KB RNA, AS WELL AS REPLICATIVE INTERMEDIATE DNA IN HBV-INFECTED HEPG2-NA(+) /TAUROCHOLATE COTRANSPORTING POLYPEPTIDE CELLS AND PRIMARY HUMAN HEPATOCYTES. IN CONTRAST, GENE SILENCING OF SIRT3 PROMOTED HBV TRANSCRIPTION AND REPLICATION. A MECHANISTIC STUDY FOUND THAT NUCLEAR SIRT3 WAS RECRUITED TO THE HBV CCCDNA, WHERE IT DEACETYLATED HISTONE 3 LYSINE 9. IMPORTANTLY, OCCUPANCY OF SIRT3 ON CCCDNA COULD INCREASE THE RECRUITMENT OF HISTONE METHYLTRANSFERASE SUPPRESSOR OF VARIEGATION 3-9 HOMOLOG 1 TO CCCDNA AND DECREASE RECRUITMENT OF SET DOMAIN CONTAINING 1A, LEADING TO A MARKED INCREASE OF TRIMETHYL-HISTONE H3 (LYS9) AND A DECREASE OF TRIMETHYL-HISTONE H3 (LYS4) ON CCCDNA. MOREOVER, SIRT3-MEDIATED HBV CCCDNA TRANSCRIPTIONAL REPRESSION INVOLVED DECREASED BINDING OF HOST RNA POLYMERASE II AND TRANSCRIPTION FACTOR YIN YANG 1 TO CCCDNA. FINALLY, HEPATITIS B VIRAL X PROTEIN COULD RELIEVE SIRT3-MEDIATED CCCDNA TRANSCRIPTIONAL REPRESSION BY INHIBITING BOTH SIRT3 EXPRESSION AND ITS RECRUITMENT TO CCCDNA. CONCLUSION: SIRT3 IS A HOST FACTOR EPIGENETICALLY RESTRICTING HBV CCCDNA TRANSCRIPTION BY ACTING COOPERATIVELY WITH HISTONE METHYLTRANSFERASE; THESE DATA PROVIDE A RATIONALE FOR THE USE OF SIRT3 ACTIVATORS IN THE PREVENTION OR TREATMENT OF HBV INFECTION. (HEPATOLOGY 2018). 2018 16 3782 22 INTERFERON THERAPY OF CHRONIC HEPATITIS B. CHRONIC HEPATITIS B (CHB) RESULTS FROM THE INABILITY OF THE HOST'S IMMUNE SYSTEM TO CONTROL VIRAL REPLICATION. INTERFERON-ALPHA (IFN-ALPHA) THERAPY CAN CONVERT CHB INTO INACTIVE HEPATITIS B VIRUS (HBV) INFECTION IN 20-30% OF THE TREATED PATIENTS. IN SPITE OF THE LOW RESPONSE RATE, IFN-ALPHA THERAPY HAS THE ADVANTAGE OF HAVING A LIMITED DURATION AND BEING EFFECTIVE EVEN AFTER THERAPY, AS DEMONSTRATED BY A MUCH HIGHER INCIDENCE OF HBSAG CLEARANCE IN RESPONDERS TO IFN-ALPHA THAN IN NATURALLY OCCURRING INACTIVE HBSAG CARRIERS. IFN-ALPHA HAS MULTIPLE ANTIVIRAL, ANTIPROLIFERATIVE, AND IMMUNOMODULATORY ACTIVITIES AND TARGETS: CELLULAR GENES (IFN-STIMULATED GENES) ACTIVATING DIFFERENT PATHWAYS OF ANTIVIRAL DEFENSE IN INFECTED AND NONINFECTED CELLS, HBV REPLICATION BLOCKING THE RNA-CONTAINING CORE PARTICLE FORMATION AND ACCELERATING THEIR DECAY, DEGRADING PREGENOMIC RNA, AND MODULATING THE NUCLEAR VIRAL MINICHROMOSOME (COVALENTLY CLOSED CIRCULAR DNA) ACTIVITY BY TARGETING ITS EPIGENETIC REGULATION AND BOTH INNATE AND ADAPTIVE IMMUNE RESPONSE. THE INTERFERENCE OF VIRAL HETEROGENEITY AND GENETIC POLYMORPHISMS OF THE HOST ON IFN-ALPHA SUSCEPTIBILITY IS UNDER INVESTIGATION. ONLY A BETTER UNDERSTANDING OF THE COMPLEX INTERPLAY BETWEEN THE DIFFERENT ACTIVITIES OF IFN-ALPHA WOULD WARRANT THE AMELIORATION OF CURRENT THERAPEUTIC STRATEGIES AND THE DESIGN OF NEW THERAPEUTIC APPROACHES. THE STUDY OF ON-TREATMENT DYNAMICS OF HBV INFECTION BY MEANS OF COMBINED QUANTITATIVE MONITORING OF SERUM HBV DNA AND HBSAG WARRANT TAILORING TREATMENT AT THE SINGLE-PATIENT LEVEL AND CAN HELP TO MAKE TREATMENT MORE COST-EFFECTIVE BY USING THE DIFFERENT COMBINATIONS OF CURRENTLY AVAILABLE ANTIVIRALS, INCLUDING IFN, MORE APPROPRIATELY. INTEGRATED MOLECULAR AND CLINICAL KNOWLEDGE IN A SYSTEMS MEDICINE FASHION IS MANDATORY TO FURTHER IMPROVE ANTIVIRAL THERAPY IN CHB. 2014 17 3246 22 HEPATITIS B VIRUS (HBV) INDUCES THE EXPRESSION OF INTERLEUKIN-8 THAT IN TURN REDUCES HBV SENSITIVITY TO INTERFERON-ALPHA. HIGH LEVELS OF SERUM INTERLEUKIN-8 (IL-8) HAVE BEEN DETECTED IN CHRONIC HEPATITIS B (CHB) PATIENTS DURING EPISODES OF HEPATITIS FLARES. WE INVESTIGATED WHETHER HEPATITIS B VIRUS (HBV) MAY DIRECTLY INDUCE IL-8 PRODUCTION AND WHETHER IL-8 MAY ANTAGONIZE INTERFERON-ALPHA (IFN-ALPHA) ANTIVIRAL ACTIVITY AGAINST HBV. WE SHOWED THAT CHB PATIENTS HAD SIGNIFICANTLY HIGHER IL-8 LEVELS BOTH IN SERUM AND IN LIVER TISSUE THAN CONTROLS. IN HBV-REPLICATING HEPG2 CELLS, IL-8 TRANSCRIPTION WAS SIGNIFICANTLY ACTIVATED. AP-1, C/EBP AND NF-KB TRANSCRIPTION FACTORS WERE CONCURRENTLY NECESSARY FOR MAXIMUM IL-8 INDUCTION. MOREOVER, HBX VIRAL PROTEIN WAS RECRUITED ONTO THE IL-8 PROMOTER AND THIS WAS PARALLELED BY IL8-BOUND HISTONE HYPERACETYLATION AND BY ACTIVE RECRUITMENT OF TRANSCRIPTIONAL COACTIVATORS. INHIBITION OF IL-8 INCREASES THE ANTIVIRAL ACTIVITY OF IFN-ALPHA AGAINST HBV. OUR RESULTS INDICATE THAT HBV ACTIVATES IL-8 GENE EXPRESSION BY TARGETING THE EPIGENETIC REGULATION OF THE IL-8 PROMOTER AND THAT IL-8 MAY CONTRIBUTE TO REDUCE HBV SENSITIVITY TO IFN-ALPHA. 2013 18 4055 26 MAPPING OF HISTONE MODIFICATIONS IN EPISOMAL HBV CCCDNA UNCOVERS AN UNUSUAL CHROMATIN ORGANIZATION AMENABLE TO EPIGENETIC MANIPULATION. CHRONIC HEPATITIS B VIRUS (HBV) INFECTION AFFECTS 240 MILLION PEOPLE WORLDWIDE AND IS A MAJOR RISK FACTOR FOR LIVER FAILURE AND HEPATOCELLULAR CARCINOMA. CURRENT ANTIVIRAL THERAPY INHIBITS CYTOPLASMIC HBV GENOMIC REPLICATION, BUT IS NOT CURATIVE BECAUSE IT DOES NOT DIRECTLY AFFECT NUCLEAR HBV CLOSED CIRCULAR DNA (CCCDNA), THE GENOMIC FORM THAT TEMPLATES VIRAL TRANSCRIPTION AND SUSTAINS VIRAL PERSISTENCE. NOVEL APPROACHES THAT DIRECTLY TARGET CCCDNA REGULATION WOULD THEREFORE BE HIGHLY DESIRABLE. CCCDNA IS ASSEMBLED WITH CELLULAR HISTONE PROTEINS INTO CHROMATIN, BUT LITTLE IS KNOWN ABOUT THE REGULATION OF HBV CHROMATIN BY HISTONE POSTTRANSLATIONAL MODIFICATIONS (PTMS). HERE, USING A NEW CCCDNA CHIP-SEQ APPROACH, WE REPORT, TO OUR KNOWLEDGE, THE FIRST GENOME-WIDE MAPS OF PTMS IN CCCDNA-CONTAINING CHROMATIN FROM DE NOVO INFECTED HEPG2 CELLS, PRIMARY HUMAN HEPATOCYTES, AND FROM HBV-INFECTED LIVER TISSUE. WE FIND HIGH LEVELS OF PTMS ASSOCIATED WITH ACTIVE TRANSCRIPTION ENRICHED AT SPECIFIC SITES WITHIN THE HBV GENOME AND, SURPRISINGLY, VERY LOW LEVELS OF PTMS LINKED TO TRANSCRIPTIONAL REPRESSION EVEN AT SILENT HBV PROMOTERS. WE SHOW THAT TRANSCRIPTION AND ACTIVE PTMS IN HBV CHROMATIN ARE REDUCED BY THE ACTIVATION OF AN INNATE IMMUNITY PATHWAY, AND THAT THIS EFFECT CAN BE RECAPITULATED WITH A SMALL MOLECULE EPIGENETIC MODIFYING AGENT, OPENING THE POSSIBILITY THAT CHROMATIN-BASED REGULATION OF CCCDNA TRANSCRIPTION COULD BE A NEW THERAPEUTIC APPROACH TO CHRONIC HBV INFECTION. 2015 19 841 31 CHEMOKINES FORM NANOPARTICLES WITH DNA AND CAN SUPERINDUCE TLR-DRIVEN IMMUNE INFLAMMATION. CHEMOKINES CONTROL THE MIGRATORY PATTERNS AND POSITIONING OF IMMUNE CELLS TO ORGANIZE IMMUNE RESPONSES TO PATHOGENS. HOWEVER, MANY CHEMOKINES HAVE BEEN ASSOCIATED WITH SYSTEMIC AUTOIMMUNE DISEASES THAT HAVE CHRONIC IFN SIGNATURES. WE REPORT THAT A SERIES OF CHEMOKINES, INCLUDING CXCL4, CXCL10, CXCL12, AND CCL5, CAN SUPERINDUCE TYPE I IFN (IFN-I) BY TLR9-ACTIVATED PLASMACYTOID DCS (PDCS), INDEPENDENTLY OF THEIR RESPECTIVE KNOWN CHEMOKINE RECEPTORS. MECHANISTICALLY, WE SHOW THAT CHEMOKINES SUCH AS CXCL4 MEDIATE TRANSCRIPTIONAL AND EPIGENETIC CHANGES IN PDCS, MOSTLY TARGETED TO THE IFN-I PATHWAYS. WE DESCRIBE THAT CHEMOKINES PHYSICALLY INTERACT WITH DNA TO FORM NANOPARTICLES THAT PROMOTE CLATHRIN-MEDIATED CELLULAR UPTAKE AND DELIVERY OF DNA IN THE EARLY ENDOSOMES OF PDCS. USING TWO SEPARATE MOUSE MODELS OF SKIN INFLAMMATION, WE OBSERVED THE PRESENCE OF CXCL4 ASSOCIATED WITH DNA IN VIVO. THESE DATA REVEAL A NONCANONICAL ROLE FOR CHEMOKINES TO SERVE AS NUCLEIC ACID DELIVERY VECTORS TO MODULATE TLR SIGNALING, WITH IMPLICATIONS FOR THE CHRONIC PRESENCE OF IFN-I BY PDCS IN AUTOIMMUNE DISEASES. 2022 20 3189 24 HBX RELIEVES CHROMATIN-MEDIATED TRANSCRIPTIONAL REPRESSION OF HEPATITIS B VIRAL CCCDNA INVOLVING SETDB1 HISTONE METHYLTRANSFERASE. BACKGROUND & AIMS: MAINTENANCE OF THE COVALENTLY CLOSED CIRCULAR HBV DNA (CCCDNA) THAT SERVES AS A TEMPLATE FOR HBV TRANSCRIPTION IS RESPONSIBLE FOR THE FAILURE OF ANTIVIRAL THERAPIES. WHILE STUDIES IN CHRONIC HEPATITIS PATIENTS HAVE SHOWN THAT HIGH VIREMIA CORRELATES WITH HYPERACETYLATION OF CCCDNA-ASSOCIATED HISTONES, THE MOLECULAR MECHANISMS CONTROLLING CCCDNA STABILITY AND TRANSCRIPTIONAL REGULATION ARE STILL POORLY UNDERSTOOD. THIS STUDY AIMED TO DECIPHER THE ROLE OF CHROMATIN AND CHROMATIN MODIFIER PROTEINS ON HBV TRANSCRIPTION. METHODS: WE ANALYZED THE CHROMATIN STRUCTURE OF ACTIVELY TRANSCRIBED OR SILENCED CCCDNA BY INFECTING PRIMARY HUMAN HEPATOCYTES AND DIFFERENTIATED HEPARG CELLS WITH WILD-TYPE VIRUS OR VIRUS DEFICIENT (HBVX-) FOR THE EXPRESSION OF HEPATITIS B VIRUS X PROTEIN (HBX), THAT IS REQUIRED FOR HBV EXPRESSION. RESULTS: IN THE ABSENCE OF HBX, HBV CCCDNA WAS TRANSCRIPTIONALLY SILENCED WITH THE CONCOMITANT DECREASE OF HISTONE 3 (H3) ACETYLATION AND H3K4ME3, INCREASE OF H3 DI- AND TRI-METHYLATION (H3K9ME) AND THE RECRUITMENT OF HETEROCHROMATIN PROTEIN 1 FACTORS (HP1) THAT CORRELATE WITH CONDENSED CHROMATIN. SETDB1 WAS FOUND TO BE THE MAIN HISTONE METHYLTRANSFERASE RESPONSIBLE FOR THE DEPOSITION OF H3K9ME3 AND HBV REPRESSION. FINALLY, FULL TRANSCRIPTIONAL REACTIVATION OF HBVX- UPON HBX RE-EXPRESSION CORRELATED WITH AN INCREASE OF HISTONE ACETYLATION AND H3K4ME3, AND A CONCOMITANT DECREASE OF HP1 BINDING AND OF H3K9ME3 ON THE CCCDNA. CONCLUSION: UPON HBV INFECTION, CELLULAR MECHANISMS INVOLVING SETDB1-MEDIATED H3K9ME3 AND HP1 INDUCE SILENCING OF HBV CCCDNA TRANSCRIPTION THROUGH MODULATION OF CHROMATIN STRUCTURE. HBX IS ABLE TO RELIEVE THIS REPRESSION AND ALLOW THE ESTABLISHMENT OF ACTIVE CHROMATIN. 2015