1 1479 87 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 2 5223 32 PRIMARY MURINE CD4+ T CELLS FAIL TO ACQUIRE THE ABILITY TO PRODUCE EFFECTOR CYTOKINES WHEN ACTIVE RAS IS PRESENT DURING TH1/TH2 DIFFERENTIATION. CONSTITUTIVE RAS SIGNALING HAS BEEN SHOWN TO AUGMENT IL-2 PRODUCTION, REVERSE ANERGY, AND FUNCTIONALLY REPLACE MANY ASPECTS OF CD28 CO-STIMULATION IN CD4+ T CELLS. THESE DATA RAISE THE POSSIBILITY THAT INTRODUCTION OF ACTIVE RAS INTO PRIMARY T CELLS MIGHT RESULT IN IMPROVED FUNCTIONALITY IN PATHOLOGIC SITUATIONS OF T CELL DYSFUNCTION, SUCH AS CANCER OR CHRONIC VIRAL INFECTION. TO TEST THE BIOLOGIC EFFECTS OF ACTIVE RAS IN PRIMARY T CELLS, CD4+ T CELLS FROM COXSACKIE-ADENOVIRUS RECEPTOR TRANSGENIC MICE WERE TRANSDUCED WITH AN ADENOVIRUS ENCODING ACTIVE RAS. AS EXPECTED, ACTIVE RAS AUGMENTED IL-2 PRODUCTION IN NAIVE CD4+ T CELLS. HOWEVER, WHEN CELLS WERE CULTURED FOR 4 DAYS UNDER CONDITIONS TO PROMOTE EFFECTOR CELL DIFFERENTIATION, ACTIVE RAS INHIBITED THE ABILITY OF CD4+ T CELLS TO ACQUIRE A TH1 OR TH2 EFFECTOR CYTOKINE PROFILE. THIS DIFFERENTIATION DEFECT WAS NOT DUE TO DEFICIENT STAT4 OR STAT6 ACTIVATION BY IL-12 OR IL-4, RESPECTIVELY, NOR WAS IT ASSOCIATED WITH DEFICIENT INDUCTION OF T-BET AND GATA-3 EXPRESSION. IMPAIRED EFFECTOR CYTOKINE PRODUCTION IN ACTIVE RAS-TRANSDUCED CELLS WAS ASSOCIATED WITH DEFICIENT DEMETHYLATION OF THE IL-4 GENE LOCUS. OUR RESULTS INDICATE THAT, DESPITE AUGMENTING ACUTE ACTIVATION OF NAIVE T CELLS, CONSTITUTIVE RAS SIGNALING INHIBITS THE ABILITY OF CD4+ T CELLS TO PROPERLY DIFFERENTIATE INTO TH1/TH2 EFFECTOR CYTOKINE-PRODUCING CELLS, IN PART BY INTERFERING WITH EPIGENETIC MODIFICATION OF EFFECTOR GENE LOCI. ALTERNATIVE STRATEGIES TO POTENTIATE RAS PATHWAY SIGNALING IN T CELLS IN A MORE REGULATED FASHION SHOULD BE CONSIDERED AS A THERAPEUTIC APPROACH TO IMPROVE IMMUNE RESPONSES IN VIVO. 2014 3 2146 26 EPIGENETIC MANIPULATION RESTORES FUNCTIONS OF DEFECTIVE CD8(+) T CELLS FROM CHRONIC VIRAL INFECTION. FUNCTIONAL EXHAUSTION OF ANTIGEN-SPECIFIC T CELLS IS A DEFINING CHARACTERISTIC OF MANY CHRONIC INFECTIONS, BUT THE UNDERLYING MECHANISMS OF T CELL DYSFUNCTION ARE NOT WELL UNDERSTOOD. EPIGENETICS PLAYS AN IMPORTANT ROLE IN THE CONTROL OF T CELL DEVELOPMENT, DIFFERENTIATION, AND FUNCTION. TO EXAMINE IF EPIGENETICS ALSO PLAYS A ROLE IN T CELL EXHAUSTION, WE ANALYZED CHROMATIN REMODELING IN CD8(+) T CELLS FROM MICE WITH CHRONIC LYMPHOCYTIC CHORIOMENINGITIS VIRUS INFECTION. WE OBSERVED DOWNREGULATION OF DIACETYLATED HISTONE H3 IN BOTH VIRUS-SPECIFIC AND TOTAL CD8(+) T CELLS, AND FUNCTIONAL DEFECTS NOT ONLY IN VIRUS-SPECIFIC CD8(+) T CELLS BUT ALSO WITHIN THE TOTAL CD8(+) T CELL POPULATION. IN VITRO TREATMENT OF THESE EXHAUSTED CD8(+) T CELLS WITH HISTONE DEACETYLASE INHIBITORS RESTORED DIACETYLATED HISTONE H3 LEVELS, AND IMPROVED THEIR IMMUNE FUNCTIONS. UPON ADOPTIVE TRANSFER, THESE TREATED CD8(+) T CELLS DEVELOPED INTO FUNCTIONAL MEMORY T CELLS IN VIVO THAT ENHANCED PROTECTIVE IMMUNITY. THESE RESULTS DEFINE A ROLE OF EPIGENETICS IN T CELL EXHAUSTION AND SUGGEST EPIGENETIC MANIPULATION AS A NOVEL MOLECULAR THERAPY TO RESTORE IMMUNE FUNCTIONS. 2014 4 6590 25 TUMOR SUPPRESSOR INACTIVATION IN THE PATHOGENESIS OF ADULT T-CELL LEUKEMIA. TUMOR SUPPRESSOR FUNCTIONS ARE ESSENTIAL TO CONTROL CELLULAR PROLIFERATION, TO ACTIVATE THE APOPTOSIS OR SENESCENCE PATHWAY TO ELIMINATE UNWANTED CELLS, TO LINK DNA DAMAGE SIGNALS TO CELL CYCLE ARREST CHECKPOINTS, TO ACTIVATE APPROPRIATE DNA REPAIR PATHWAYS, AND TO PREVENT THE LOSS OF ADHESION TO INHIBIT INITIATION OF METASTASES. THEREFORE, TUMOR SUPPRESSOR GENES ARE INDISPENSABLE TO MAINTAINING GENETIC AND GENOMIC INTEGRITY. CONSEQUENTLY, INACTIVATION OF TUMOR SUPPRESSORS BY SOMATIC MUTATIONS OR EPIGENETIC MECHANISMS IS FREQUENTLY ASSOCIATED WITH TUMOR INITIATION AND DEVELOPMENT. IN CONTRAST, REACTIVATION OF TUMOR SUPPRESSOR FUNCTIONS CAN EFFECTIVELY REVERSE THE TRANSFORMED PHENOTYPE AND LEAD TO CELL CYCLE ARREST OR DEATH OF CANCEROUS CELLS AND BE USED AS A THERAPEUTIC STRATEGY. ADULT T-CELL LEUKEMIA/LYMPHOMA (ATLL) IS AN AGGRESSIVE LYMPHOPROLIFERATIVE DISEASE ASSOCIATED WITH INFECTION OF CD4 T CELLS BY THE HUMAN T-CELL LEUKEMIA VIRUS TYPE 1 (HTLV-I). HTLV-I-ASSOCIATED T-CELL TRANSFORMATION IS THE RESULT OF A MULTISTEP ONCOGENIC PROCESS IN WHICH THE VIRUS INITIALLY INDUCES CHRONIC T-CELL PROLIFERATION AND ALTERS CELLULAR PATHWAYS RESULTING IN THE ACCUMULATION OF GENETIC DEFECTS AND THE DEREGULATED GROWTH OF VIRALLY INFECTED CELLS. THIS REVIEW WILL FOCUS ON THE CURRENT KNOWLEDGE OF THE GENETIC AND EPIGENETIC MECHANISMS REGULATING THE INACTIVATION OF TUMOR SUPPRESSORS IN THE PATHOGENESIS OF HTLV-I. 2015 5 5477 23 RESTORING THE FUNCTIONAL IMMUNOGENICITY OF CHRONIC LYMPHOCYTIC LEUKEMIA USING EPIGENETIC MODIFIERS. CHRONIC LYMPHOCYTIC LEUKEMIA (CLL) IS A MALIGNANCY ARISING FROM IMMUNE CELLS (B-LYMPHOCYTES) ENDOWED WITH INTRINSIC ANTIGEN-PRESENTING CAPABILITIES. SUCH A FUNCTION HOWEVER IS LOST DURING MALIGNANT TRANSFORMATION AND CLL CELLS ARE WELL KNOWN FOR THEIR INABILITY TO PROCESS AND PRESENT ANTIGENS TO THE T-CELL ARM OF THE IMMUNE SYSTEM. INSTEAD, MALIGNANT CLL CELLS ELICIT A VAST ARRAY OF IMMUNE REGULATORY MECHANISMS CONDUCIVE TO T-CELL DYSFUNCTION AND IMMUNOSUPPRESSION. PREVIOUSLY, WE HAVE SHOWN THAT TREATMENT OF CLL CELLS WITH THE DEMETHYLATING AGENT 5-AZA-2'-DEOXYCYTIDINE UNLEASHED TARGET ANTIGEN EXPRESSION. HERE WE SHOW FOR THE FIRST TIME THAT COMBINING TWO EPIGENETIC MODIFIERS, 5-AZA-2'-DEOXYCYTIDINE AND THE HISTONE DEACETYLASE INHIBITOR LAQ824 EFFECTIVELY RESTORES THE IMMUNOGENICITY OF CLL CELL LINES AS WELL AS PRIMARY CELLS OBTAINED FROM CLL PATIENTS. INDEED, SUCH A COMBINATION INDUCES THE EXPRESSION OF NOVEL AND HIGHLY ANTIGENIC CANCER-TESTIS ANTIGENS (CTAS) AND COSTIMULATORY MOLECULES. THESE CHANGES FACILITATE THE FORMATION OF ROBUST SUPRAMOLECULAR ACTIVATION COMPLEXES (SMAC) BETWEEN CLL CELLS AND RESPONDER T-CELLS LEADING TO INTRACELLULAR SIGNALING, LYTIC GRANULE MOBILIZATION, AND POLARIZATION OF FUNCTIONAL AND RELEVANT T-CELL RESPONSES. THIS CASCADE OF T-CELL ACTIVATING EVENTS TRIGGERED BY CLL CELLS WITH RESTORED APC FUNCTION, POINTS TO COMBINED EPIGENETIC MODIFIER TREATMENT AS A POTENTIAL IMMUNOTHERAPEUTIC STRATEGY FOR CLL PATIENTS. 2011 6 3043 31 GENOME-WIDE ANALYSIS IDENTIFIES NR4A1 AS A KEY MEDIATOR OF T CELL DYSFUNCTION. T CELLS BECOME DYSFUNCTIONAL WHEN THEY ENCOUNTER SELF ANTIGENS OR ARE EXPOSED TO CHRONIC INFECTION OR TO THE TUMOUR MICROENVIRONMENT(1). THE FUNCTION OF T CELLS IS TIGHTLY REGULATED BY A COMBINATIONAL CO-STIMULATORY SIGNAL, AND DOMINANCE OF NEGATIVE CO-STIMULATION RESULTS IN T CELL DYSFUNCTION(2). HOWEVER, THE MOLECULAR MECHANISMS THAT UNDERLIE THIS DYSFUNCTION REMAIN UNCLEAR. HERE, USING AN IN VITRO T CELL TOLERANCE INDUCTION SYSTEM IN MICE, WE CHARACTERIZE GENOME-WIDE EPIGENETIC AND GENE EXPRESSION FEATURES IN TOLERANT T CELLS, AND SHOW THAT THEY ARE DISTINCT FROM EFFECTOR AND REGULATORY T CELLS. NOTABLY, THE TRANSCRIPTION FACTOR NR4A1 IS STABLY EXPRESSED AT HIGH LEVELS IN TOLERANT T CELLS. OVEREXPRESSION OF NR4A1 INHIBITS EFFECTOR T CELL DIFFERENTIATION, WHEREAS DELETION OF NR4A1 OVERCOMES T CELL TOLERANCE AND EXAGGERATES EFFECTOR FUNCTION, AS WELL AS ENHANCING IMMUNITY AGAINST TUMOUR AND CHRONIC VIRUS. MECHANISTICALLY, NR4A1 IS PREFERENTIALLY RECRUITED TO BINDING SITES OF THE TRANSCRIPTION FACTOR AP-1, WHERE IT REPRESSES EFFECTOR-GENE EXPRESSION BY INHIBITING AP-1 FUNCTION. NR4A1 BINDING ALSO PROMOTES ACETYLATION OF HISTONE 3 AT LYSINE 27 (H3K27AC), LEADING TO ACTIVATION OF TOLERANCE-RELATED GENES. THIS STUDY THUS IDENTIFIES NR4A1 AS A KEY GENERAL REGULATOR IN THE INDUCTION OF T CELL DYSFUNCTION, AND A POTENTIAL TARGET FOR TUMOUR IMMUNOTHERAPY. 2019 7 5704 24 SINGLE-CELL RNA-SEQ REVEALS TOX AS A KEY REGULATOR OF CD8(+) T CELL PERSISTENCE IN CHRONIC INFECTION. PROGENITOR-LIKE CD8(+) T CELLS MEDIATE LONG-TERM IMMUNITY TO CHRONIC INFECTION AND CANCER AND RESPOND POTENTLY TO IMMUNE CHECKPOINT BLOCKADE. THESE CELLS SHARE TRANSCRIPTIONAL REGULATORS WITH MEMORY PRECURSOR CELLS, INCLUDING T CELL-SPECIFIC TRANSCRIPTION FACTOR 1 (TCF1), BUT IT IS UNCLEAR WHETHER THEY ADOPT DISTINCT PROGRAMS TO ADAPT TO THE IMMUNOSUPPRESSIVE ENVIRONMENT. BY COMPARING THE SINGLE-CELL TRANSCRIPTOMES AND EPIGENETIC PROFILES OF CD8(+) T CELLS RESPONDING TO ACUTE AND CHRONIC VIRAL INFECTIONS, WE FOUND THAT PROGENITOR-LIKE CD8(+) T CELLS BECAME DISTINCT FROM MEMORY PRECURSOR CELLS BEFORE THE PEAK OF THE T CELL RESPONSE. WE DISCOVERED A COEXPRESSION GENE MODULE CONTAINING TOX THAT EXHIBITED HIGHER TRANSCRIPTIONAL ACTIVITY ASSOCIATED WITH MORE ABUNDANT ACTIVE HISTONE MARKS IN PROGENITOR-LIKE CELLS THAN MEMORY PRECURSOR CELLS. MOREOVER, THYMOCYTE SELECTION-ASSOCIATED HIGH MOBILITY GROUP BOX PROTEIN TOX (TOX) PROMOTED THE PERSISTENCE OF ANTIVIRAL CD8(+) T CELLS AND WAS REQUIRED FOR THE PROGRAMMING OF PROGENITOR-LIKE CD8(+) T CELLS. THUS, LONG-TERM CD8(+) T CELL IMMUNITY TO CHRONIC VIRAL INFECTION REQUIRES UNIQUE TRANSCRIPTIONAL AND EPIGENETIC PROGRAMS ASSOCIATED WITH THE TRANSCRIPTION FACTOR TOX. 2019 8 1759 21 EARLY PRECURSOR T CELLS ESTABLISH AND PROPAGATE T CELL EXHAUSTION IN CHRONIC INFECTION. CD8(+) T CELLS RESPONDING TO CHRONIC INFECTIONS OR TUMORS ACQUIRE AN 'EXHAUSTED' STATE ASSOCIATED WITH ELEVATED EXPRESSION OF INHIBITORY RECEPTORS, INCLUDING PD-1, AND IMPAIRED CYTOKINE PRODUCTION. EXHAUSTED T CELLS ARE CONTINUOUSLY REPLENISHED BY T CELLS WITH PRECURSOR CHARACTERISTICS THAT SELF-RENEW AND DEPEND ON THE TRANSCRIPTION FACTOR TCF1; HOWEVER, THEIR DEVELOPMENTAL REQUIREMENTS ARE POORLY UNDERSTOOD. IN THE PRESENT STUDY, WE DEMONSTRATE THAT HIGH ANTIGEN LOAD PROMOTED THE DIFFERENTIATION OF PRECURSOR T CELLS, WHICH ACQUIRED HALLMARKS OF EXHAUSTION WITHIN DAYS OF INFECTION, WHEREAS EARLY EFFECTOR CELLS RETAINED POLYFUNCTIONAL FEATURES. EARLY PRECURSOR T CELLS SHOWED EPIGENETIC IMPRINTING CHARACTERISTIC OF T CELL RECEPTOR-DEPENDENT TRANSCRIPTION FACTOR BINDING AND WERE RESTRICTED TO THE GENERATION OF CELLS DISPLAYING EXHAUSTION CHARACTERISTICS. TRANSCRIPTION FACTORS BACH2 AND BATF WERE KEY REGULATORS WITH OPPOSING FUNCTIONS IN THE GENERATION OF EARLY PRECURSOR T CELLS. OVERALL, WE DEMONSTRATE THAT EXHAUSTION MANIFESTS FIRST IN TCF1(+) PRECURSOR T CELLS AND IS PROPAGATED SUBSEQUENTLY TO THE POOL OF ANTIGEN-SPECIFIC T CELLS. 2020 9 6293 29 THE PRO- AND ANTI-INFLAMMATORY POTENTIAL OF IL-12: THE DUAL ROLE OF TH1 CELLS. THE DIFFERENTIATION OF T-HELPER (TH) LYMPHOCYTES INTO VARIOUS TYPES OF T-HELPER EFFECTOR AND MEMORY CELLS WITH DISTINCT FUNCTIONS DEPENDING ON THE TYPE OF CONCOMITANT SIGNALS THEY RECEIVE UPON ACTIVATION IS A CRITICAL EVENT DETERMINING THE COURSE OF AN IMMUNE REACTION. TH1 CELLS CHARACTERIZED BY THE EXPRESSION OF IFN-GAMMA AND THE RECENTLY DESCRIBED TH17 CELLS PROMOTE INFLAMMATION AND ARE CRITICALLY INVOLVED IN THE INDUCTION AND MAINTENANCE OF AUTOIMMUNITY, WHEREAS THE SECRETION OF IL-4 IS A HALLMARK OF TH2 CELLS MEDIATING PROTECTION FROM PARASITES AND ALLERGY. ORIGINAL STIMULATION IN THE PRESENCE OF IL-12 RESULTS IN THE IMPRINTING OF TH1 MEMORY CELLS FOR THE EXPRESSION OF IFN-GAMMA BY EXPRESSION OF THE TRANSCRIPTION FACTOR T-BET AND EPIGENETIC MODIFICATION OF THE IFNGAMMA GENE. IT HAS BEEN DEMONSTRATED THAT TH1 CELLS ARE POTENT INDUCERS OF INFLAMMATION. HOWEVER, IN THE CHRONIC PHASE OF SUCH INFLAMMATION, THE REGULATORY POTENTIAL OF IL-12 AND TH1 CELLS THEMSELVES MAY PLAY AN IMPORTANT ROLE IN LIMITING IMMUNOPATHOLOGY. 2007 10 5795 25 STAT3 INDUCTION OF MIR-146B FORMS A FEEDBACK LOOP TO INHIBIT THE NF-KAPPAB TO IL-6 SIGNALING AXIS AND STAT3-DRIVEN CANCER PHENOTYPES. INTERLEUKIN-6 (IL-6)-MEDIATED ACTIVATION OF SIGNAL TRANSDUCER AND ACTIVATOR OF TRANSCRIPTION 3 (STAT3) IS A MECHANISM BY WHICH CHRONIC INFLAMMATION CAN CONTRIBUTE TO CANCER AND IS A COMMON ONCOGENIC EVENT. WE DISCOVERED A PATHWAY, THE LOSS OF WHICH IS ASSOCIATED WITH PERSISTENT STAT3 ACTIVATION IN HUMAN CANCER. WE FOUND THAT THE GENE ENCODING THE TUMOR SUPPRESSOR MICRORNA MIR-146B IS A DIRECT STAT3 TARGET GENE, AND ITS EXPRESSION WAS INCREASED IN NORMAL BREAST EPITHELIAL CELLS BUT DECREASED IN TUMOR CELLS. METHYLATION OF THE MIR-146B PROMOTER, WHICH INHIBITED STAT3-MEDIATED INDUCTION OF EXPRESSION, WAS INCREASED IN PRIMARY BREAST CANCERS. MOREOVER, WE FOUND THAT MIR-146B INHIBITED NUCLEAR FACTOR KAPPAB (NF-KAPPAB)-DEPENDENT PRODUCTION OF IL-6, SUBSEQUENT STAT3 ACTIVATION, AND IL-6/STAT3-DRIVEN MIGRATION AND INVASION IN BREAST CANCER CELLS, THEREBY ESTABLISHING A NEGATIVE FEEDBACK LOOP. IN ADDITION, HIGHER EXPRESSION OF MIR-146B WAS POSITIVELY CORRELATED WITH PATIENT SURVIVAL IN BREAST CANCER SUBTYPES WITH INCREASED IL6 EXPRESSION AND STAT3 PHOSPHORYLATION. OUR RESULTS IDENTIFY AN EPIGENETIC MECHANISM OF CROSSTALK BETWEEN STAT3 AND NF-KAPPAB RELEVANT TO CONSTITUTIVE STAT3 ACTIVATION IN MALIGNANCY AND THE ROLE OF INFLAMMATION IN ONCOGENESIS. 2014 11 942 26 CHRONIC LYMPHOCYTIC LEUKEMIA PRESENCE IMPAIRS ANTIGEN-SPECIFIC CD8(+) T-CELL RESPONSES THROUGH EPIGENETIC REPROGRAMMING TOWARDS SHORT-LIVED EFFECTORS. T-CELL DYSREGULATION IN CHRONIC LYMPHOCYTIC LEUKEMIA (CLL) ASSOCIATES WITH LOW RESPONSE RATES TO AUTOLOGOUS T CELL-BASED THERAPIES. HOW CLL AFFECTS ANTIGEN-SPECIFIC T-CELL RESPONSES REMAINS LARGELY UNKNOWN. WE INVESTIGATED (EPI)GENETIC AND FUNCTIONAL CONSEQUENCES OF ANTIGEN-SPECIFIC T-CELL RESPONSES IN PRESENCE OF CLL IN VITRO AND IN AN ADOPTIVE-TRANSFER MURINE MODEL. ALREADY AT STEADY-STATE, ANTIGEN-EXPERIENCED PATIENT-DERIVED T CELLS WERE SKEWED TOWARDS SHORT-LIVED EFFECTOR CELLS (SLEC) AT THE EXPENSE OF MEMORY-PRECURSOR EFFECTOR CELLS (MPEC). STIMULATION OF THESE T CELLS IN VITRO SHOWED RAPID INDUCTION OF EFFECTOR GENES AND SUPPRESSION OF KEY MEMORY TRANSCRIPTION FACTORS ONLY IN PRESENCE OF CLL CELLS, INDICATING EPIGENETIC REGULATION. THIS WAS INVESTIGATED IN VIVO BY FOLLOWING ANTIGEN-SPECIFIC RESPONSES OF NAIVE OT-I CD8(+) CELLS TO MCMV-OVA IN PRESENCE/ABSENCE OF TCL1 B-CELL LEUKEMIA. PRESENCE OF LEUKEMIA RESULTED IN INCREASED SLEC FORMATION, WITH DISTURBED INFLAMMATORY CYTOKINE PRODUCTION. CHROMATIN AND TRANSCRIPTOME PROFILING REVEALED STRONG EPIGENETIC MODIFICATIONS, LEADING TO ACTIVATION OF AN EFFECTOR AND SILENCING OF A MEMORY PROFILE THROUGH PRESENCE OF CLL CELLS. SECONDARY CHALLENGE IN VIVO CONFIRMED DYSFUNCTIONAL MEMORY RESPONSES BY ANTIGEN-EXPERIENCED OT-I CELLS GENERATED IN PRESENCE OF CLL. ALTOGETHER, WE SHOW THAT PRESENCE OF CLL INDUCES A SHORT-LIVED EFFECTOR PHENOTYPE AND IMPAIRED MEMORY RESPONSES BY EPIGENETIC REPROGRAMMING DURING PRIMARY RESPONSES. 2023 12 2928 22 GENERATION OF IPSCS FROM CULTURED HUMAN MALIGNANT CELLS. INDUCED PLURIPOTENT STEM CELLS (IPSCS) CAN BE GENERATED FROM VARIOUS DIFFERENTIATED CELL TYPES BY THE EXPRESSION OF A SET OF DEFINED TRANSCRIPTION FACTORS. SO FAR, IPSCS HAVE BEEN GENERATED FROM PRIMARY CELLS, BUT IT IS UNCLEAR WHETHER HUMAN CANCER CELL LINES CAN BE REPROGRAMMED. HERE WE DESCRIBE THE GENERATION AND CHARACTERIZATION OF IPSCS DERIVED FROM HUMAN CHRONIC MYELOID LEUKEMIA CELLS. WE SHOW THAT, DESPITE THE PRESENCE OF ONCOGENIC MUTATIONS, THESE CELLS ACQUIRED PLURIPOTENCY BY THE EXPRESSION OF 4 TRANSCRIPTION FACTORS AND UNDERWENT DIFFERENTIATION INTO CELL TYPES DERIVED OF ALL 3 GERM LAYERS DURING TERATOMA FORMATION. INTERESTINGLY, ALTHOUGH THE PARENTAL CELL LINE WAS STRICTLY DEPENDENT ON CONTINUOUS SIGNALING OF THE BCR-ABL ONCOGENE, ALSO TERMED ONCOGENE ADDICTION, REPROGRAMMED CELLS LOST THIS DEPENDENCY AND BECAME RESISTANT TO THE BCR-ABL INHIBITOR IMATINIB. THIS FINDING INDICATES THAT THE THERAPEUTIC AGENT IMATINIB TARGETS CELLS IN A SPECIFIC EPIGENETIC DIFFERENTIATED CELL STATE, AND THIS MAY CONTRIBUTE TO ITS INABILITY TO FULLY ERADICATE DISEASE IN CHRONIC MYELOID LEUKEMIA PATIENTS. 2010 13 1319 24 DEMETHYLATION OF THE PD-1 PROMOTER IS IMPRINTED DURING THE EFFECTOR PHASE OF CD8 T CELL EXHAUSTION. PD-1 IS AN INHIBITORY RECEPTOR THAT HAS A MAJOR ROLE IN T CELL DYSFUNCTION DURING CHRONIC INFECTIONS AND CANCER. WHILE DEMETHYLATION OF THE PD-1 PROMOTER DNA IS OBSERVED IN EXHAUSTED T CELLS ISOLATED FROM CHRONICALLY INFECTED INDIVIDUALS, LITTLE IS KNOWN ABOUT WHEN THIS STABLE DEMETHYLATION OF PD-1 PROMOTER DNA IS PROGRAMMED DURING THE COURSE OF A CHRONIC INFECTION. TO ASSESS IF PD-1 PROMOTER DNA DEMETHYLATION IS IMPACTED BY PROLONGED STIMULATION DURING EFFECTOR PHASE OF CHRONIC INFECTION, WE ADOPTIVELY TRANSFERRED VIRUS-SPECIFIC DAY 8 EFFECTOR CD8 T CELLS FROM MICE INFECTED WITH LYMPHOCYTIC CHORIOMENINGITIS VIRUS (LCMV) CLONE 13 INTO RECIPIENT MICE THAT HAD CLEARED AN ACUTE INFECTION. WE OBSERVED THAT LCMV-SPECIFIC CD8 T CELLS FROM CHRONICALLY INFECTED MICE MAINTAINED THEIR SURFACE EXPRESSION OF PD-1 EVEN AFTER TRANSFER INTO ACUTE IMMUNE MICE UNTIL DAY 45 POSTTRANSFER. INTERESTINGLY, THE PD-1 TRANSCRIPTIONAL REGULATORY REGION CONTINUED TO REMAIN UNMETHYLATED IN THESE DONOR CD8 T CELLS GENERATED FROM A CHRONIC INFECTION. THE OBSERVED MAINTENANCE OF PD-1 SURFACE EXPRESSION AND THE DEMETHYLATED PD-1 PROMOTER WERE NOT A RESULT OF RESIDUAL ANTIGEN IN THE RECIPIENT MICE, BECAUSE SIMILAR RESULTS WERE SEEN WHEN CHRONIC INFECTION-INDUCED EFFECTOR CELLS WERE TRANSFERRED INTO MICE INFECTED WITH A VARIANT STRAIN OF LCMV (LCMV V35A) BEARING A MUTATION IN THE COGNATE MAJOR HISTOCOMPATIBILITY COMPLEX CLASS I (MHC-I) EPITOPE THAT IS RECOGNIZED BY THE DONOR CD8 T CELLS. IMPORTANTLY, THE MAINTENANCE OF PD-1 PROMOTER DEMETHYLATION IN MEMORY CD8 T CELLS WAS COUPLED WITH IMPAIRED CLONAL EXPANSION AND HIGHER PD-1 RE-EXPRESSION UPON SECONDARY CHALLENGE. THESE DATA SHOW THAT THE IMPRINTING OF THE EPIGENETIC PROGRAM OF THE INHIBITORY RECEPTOR PD-1 OCCURS DURING THE EFFECTOR PHASE OF CHRONIC VIRAL INFECTION. IMPORTANCE: SINCE PD-1 IS A MAJOR INHIBITORY RECEPTOR REGULATING T CELL DYSFUNCTION DURING CHRONIC VIRAL INFECTION AND CANCERS, A BETTER UNDERSTANDING OF THE MECHANISMS THAT REGULATE PD-1 EXPRESSION IS IMPORTANT. IN THIS WORK, WE DEMONSTRATE THAT THE PD-1 EPIGENETIC PROGRAM IN ANTIGEN-SPECIFIC CD8 T CELLS IS FIXED DURING THE PRIMING PHASE OF CHRONIC INFECTION. 2016 14 3795 26 INTERLEUKIN-6 CONTRIBUTES TO GROWTH IN CHOLANGIOCARCINOMA CELLS BY ABERRANT PROMOTER METHYLATION AND GENE EXPRESSION. THE ASSOCIATION BETWEEN CHRONIC INFLAMMATION AND THE DEVELOPMENT AND PROGRESSION OF MALIGNANCY IS EXEMPLIFIED IN THE BILIARY TRACT WHERE PERSISTENT INFLAMMATION STRONGLY PREDISPOSES TO CHOLANGIOCARCINOMA. THE INFLAMMATORY CYTOKINE INTERLEUKIN-6 (IL-6) ENHANCES TUMOR GROWTH IN CHOLANGIOCARCINOMA BY ALTERED GENE EXPRESSION VIA AUTOCRINE MECHANISMS. IL-6 CAN REGULATE THE ACTIVITY OF DNA METHYLTRANSFERASES, AND MOREOVER, ABERRANT DNA METHYLATION CAN CONTRIBUTE TO CARCINOGENESIS. WE THEREFORE INVESTIGATED THE EFFECT OF CHRONIC EXPOSURE TO IL-6 ON METHYLATION-DEPENDENT GENE EXPRESSION AND TRANSFORMED CELL GROWTH IN HUMAN CHOLANGIOCARCINOMA. THE RELATIONSHIP BETWEEN AUTOCRINE IL-6 PATHWAYS, DNA METHYLATION, AND TRANSFORMED CELL GROWTH WAS ASSESSED USING MALIGNANT CHOLANGIOCYTES STABLY TRANSFECTED TO OVEREXPRESS IL-6. TREATMENT WITH THE DNA METHYLATION INHIBITOR 5-AZA-2'-DEOXYCYTIDINE DECREASED CELL PROLIFERATION, GROWTH IN SOFT AGAR, AND METHYLCYTOSINE CONTENT OF MALIGNANT CHOLANGIOCYTES. HOWEVER, THIS EFFECT WAS NOT OBSERVED IN IL-6-OVEREXPRESSING CELLS. IL-6 OVEREXPRESSION RESULTED IN THE ALTERED EXPRESSION AND PROMOTER METHYLATION OF SEVERAL GENES, INCLUDING THE EPIDERMAL GROWTH FACTOR RECEPTOR (EGFR). EGFR PROMOTER METHYLATION WAS DECREASED AND GENE AND PROTEIN EXPRESSION WAS INCREASED BY IL-6. THUS, EPIGENETIC REGULATION OF GENE EXPRESSION BY IL-6 CAN CONTRIBUTE TO TUMOR PROGRESSION BY ALTERING PROMOTER METHYLATION AND GENE EXPRESSION OF GROWTH-REGULATORY PATHWAYS, SUCH AS THOSE INVOLVING EGFR. MOREOVER, ENHANCED IL-6 EXPRESSION MAY DECREASE THE SENSITIVITY OF TUMOR CELLS TO THERAPEUTIC TREATMENTS USING METHYLATION INHIBITORS. THESE OBSERVATIONS HAVE IMPORTANT IMPLICATIONS FOR CANCER TREATMENT AND PROVIDE A MECHANISM BY WHICH PERSISTENT CYTOKINE STIMULATION CAN PROMOTE TUMOR GROWTH. 2006 15 991 24 CHRONIC STIMULATION DRIVES HUMAN NK CELL DYSFUNCTION AND EPIGENETIC REPROGRAMING. A POPULATION OF NATURAL KILLER (NK) CELLS EXPRESSING THE ACTIVATING RECEPTOR NKG2C AND THE MATURATION MARKER CD57 EXPANDS IN RESPONSE TO HUMAN CYTOMEGALOVIRUS (HCMV) INFECTION. CD3-CD56DIMCD57+NKG2C+ NK CELLS ARE SIMILAR TO CD8+ MEMORY T CELLS WITH RAPID AND ROBUST EFFECTOR FUNCTION UPON RE-STIMULATION, PERSISTENCE, AND EPIGENETIC REMODELING OF THE IFNG LOCUS. CHRONIC ANTIGEN STIMULATION DRIVES CD8+ MEMORY T CELL PROLIFERATION WHILE ALSO INDUCING GENOME-WIDE EPIGENETIC REPROGRAMING AND DYSFUNCTION. WE HYPOTHESIZED THAT CHRONIC STIMULATION COULD SIMILARLY INDUCE EPIGENETIC REPROGRAMING AND DYSFUNCTION IN NK CELLS. HERE WE SHOW THAT CHRONIC STIMULATION OF ADAPTIVE NK CELLS THROUGH NKG2C USING PLATE-BOUND AGONISTIC ANTIBODIES IN COMBINATION WITH IL-15 DROVE ROBUST PROLIFERATION AND ACTIVATION OF CD3-CD56DIMCD57+NKG2C+ NK CELLS WHILE SIMULTANEOUSLY INDUCING HIGH EXPRESSION OF THE CHECKPOINT INHIBITORY RECEPTORS LAG-3 AND PD-1. MARKED INDUCTION OF CHECKPOINT INHIBITORY RECEPTORS WAS ALSO OBSERVED ON THE SURFACE OF ADAPTIVE NK CELLS CO-CULTURED WITH HCMV-INFECTED ENDOTHELIAL CELLS. CHRONICALLY STIMULATED ADAPTIVE NK CELLS WERE DYSFUNCTIONAL WHEN CHALLENGED WITH TUMOR TARGETS. THESE CELLS EXHIBITED A PATTERN OF EPIGENETIC REPROGRAMING, WITH GENOME-WIDE ALTERATIONS IN DNA METHYLATION. OUR STUDY HAS IMPORTANT IMPLICATIONS FOR CANCER IMMUNOTHERAPY AND SUGGEST THAT EXHAUSTED NK CELLS COULD BE TARGETED WITH INHIBITORY CHECKPOINT RECEPTOR BLOCKADE. 2019 16 6521 27 TRANSCRIPTIONAL AND EPIGENETIC REGULATION OF PD-1 EXPRESSION. PROGRAMMED CELL DEATH-1 (PD-1) IS A CO-INHIBITORY RECEPTOR THAT PLAYS IMPORTANT ROLES IN REGULATING T CELL IMMUNITY AND PERIPHERAL TOLERANCE. PD-1 SIGNALING PREVENTS T CELLS FROM OVERACTIVATION DURING ACUTE INFECTIONS, BUT IT MAINTAINS T CELL EXHAUSTION DURING CHRONIC INFECTIONS. TUMOR CELLS CAN EXPLOIT THE PD-1 SIGNALING PATHWAY TO EVADE ANTITUMOR IMMUNE RESPONSES. THE PD-1 SIGNALING PATHWAY IS ALSO ESSENTIAL FOR MAINTAINING PERIPHERAL TOLERANCE AND PREVENTION OF AUTOIMMUNITY. PD-1 EXPRESSION IS STRICTLY AND DIFFERENTIALLY REGULATED BY DIVERSE MECHANISMS IN IMMUNE CELLS. IT IS ACTIVATED AND REPRESSED BY DISTINCT TRANSCRIPTION FACTORS IN DIFFERENT CIRCUMSTANCES. MOREOVER, EPIGENETIC MECHANISMS ARE ALSO INVOLVED IN REGULATING PD-1 EXPRESSION. IN THIS REVIEW, WE SUMMARIZE THE KNOWLEDGE OF THE TRANSCRIPTIONAL AND EPIGENETIC REGULATION OF PD-1 EXPRESSION DURING DIFFERENT IMMUNE RESPONSES. 2021 17 2056 24 EPIGENETIC CONTROL OF CD8(+) T CELL DIFFERENTIATION. UPON STIMULATION, SMALL NUMBERS OF NAIVE CD8(+) T CELLS PROLIFERATE AND DIFFERENTIATE INTO A VARIETY OF MEMORY AND EFFECTOR CELL TYPES. CD8(+) T CELLS CAN PERSIST FOR YEARS AND KILL TUMOUR CELLS AND VIRALLY INFECTED CELLS. THE FUNCTIONAL AND PHENOTYPIC CHANGES THAT OCCUR DURING CD8(+) T CELL DIFFERENTIATION ARE WELL CHARACTERIZED, BUT THE EPIGENETIC STATES THAT UNDERLIE THESE CHANGES ARE INCOMPLETELY UNDERSTOOD. HERE, WE REVIEW THE EPIGENETIC PROCESSES THAT DIRECT CD8(+) T CELL DIFFERENTIATION AND FUNCTION. WE FOCUS ON EPIGENETIC MODIFICATION OF DNA AND ASSOCIATED HISTONES AT GENES AND THEIR REGULATORY ELEMENTS. WE ALSO DESCRIBE STRUCTURAL CHANGES IN CHROMATIN ORGANIZATION THAT AFFECT GENE EXPRESSION. FINALLY, WE EXAMINE THE TRANSLATIONAL POTENTIAL OF EPIGENETIC INTERVENTIONS TO IMPROVE CD8(+) T CELL FUNCTION IN INDIVIDUALS WITH CHRONIC INFECTIONS AND CANCER. 2018 18 730 26 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 19 4386 21 MITOCHONDRIAL STRESS INDUCED BY CONTINUOUS STIMULATION UNDER HYPOXIA RAPIDLY DRIVES T CELL EXHAUSTION. CANCER AND CHRONIC INFECTIONS INDUCE T CELL EXHAUSTION, A HYPOFUNCTIONAL FATE CARRYING DISTINCT EPIGENETIC, TRANSCRIPTOMIC AND METABOLIC CHARACTERISTICS. HOWEVER, DRIVERS OF EXHAUSTION REMAIN POORLY UNDERSTOOD. AS INTRATUMORAL EXHAUSTED T CELLS EXPERIENCE SEVERE HYPOXIA, WE HYPOTHESIZED THAT METABOLIC STRESS ALTERS THEIR RESPONSES TO OTHER SIGNALS, SPECIFICALLY, PERSISTENT ANTIGENIC STIMULATION. IN VITRO, ALTHOUGH CD8(+) T CELLS EXPERIENCING CONTINUOUS STIMULATION OR HYPOXIA ALONE DIFFERENTIATED INTO FUNCTIONAL EFFECTORS, THE COMBINATION RAPIDLY DROVE T CELL DYSFUNCTION CONSISTENT WITH EXHAUSTION. CONTINUOUS STIMULATION PROMOTED BLIMP-1-MEDIATED REPRESSION OF PGC-1ALPHA-DEPENDENT MITOCHONDRIAL REPROGRAMMING, RENDERING CELLS POORLY RESPONSIVE TO HYPOXIA. LOSS OF MITOCHONDRIAL FUNCTION GENERATED INTOLERABLE LEVELS OF REACTIVE OXYGEN SPECIES (ROS), SUFFICIENT TO PROMOTE EXHAUSTED-LIKE STATES, IN PART THROUGH PHOSPHATASE INHIBITION AND THE CONSEQUENT ACTIVITY OF NUCLEAR FACTOR OF ACTIVATED T CELLS. REDUCING T CELL-INTRINSIC ROS AND LOWERING TUMOR HYPOXIA LIMITED T CELL EXHAUSTION, SYNERGIZING WITH IMMUNOTHERAPY. THUS, IMMUNOLOGIC AND METABOLIC SIGNALING ARE INTRINSICALLY LINKED: THROUGH MITIGATION OF METABOLIC STRESS, T CELL DIFFERENTIATION CAN BE ALTERED TO PROMOTE MORE FUNCTIONAL CELLULAR FATES. 2021 20 6151 23 THE FIRE WITHIN: CELL-AUTONOMOUS MECHANISMS IN INFLAMMATION-DRIVEN CANCER. INFLAMMATORY CELLS ARE IMPORTANT FOR TUMOR INITIATION AND PROMOTION, PROVIDING CANCER CELLS WITH CYTOKINES THAT ENHANCE CELL PROLIFERATION AND SURVIVAL. ALTHOUGH MALIGNANT EPITHELIAL CELLS WERE TRADITIONALLY CONSIDERED TO BE ON THE RECEIVING END OF THESE MICROENVIRONMENTAL INTERACTIONS, RECENT STUDIES SHOW THAT EPITHELIAL CELLS CAN UNDERGO INFLAMMATORY REPROGRAMMING ON THEIR OWN. SUCH EPIGENETIC SWITCHES ARE OFTEN TRIGGERED BY CHRONIC TISSUE INJURY AND PLAY IMPORTANT ROLES IN TISSUE REPAIR. BY CONVERTING TERMINALLY DIFFERENTIATED CELLS THAT HARBOR EVEN A SINGLE ONCOGENIC MUTATION TO A LESS DIFFERENTIATED STATE WITH A HIGHER PROLIFERATIVE POTENTIAL, CELL-AUTONOMOUS INFLAMMATION IS AN IMPORTANT CONTRIBUTOR TO TUMOR INITIATION. 2019