1 2196 112 EPIGENETIC MODIFICATION MEDIATES THE INCREASE OF LAG-3(+) T CELLS IN CHRONIC OSTEOMYELITIS. IMMUNE SUPPRESSION PLAYS CRITICAL ROLES IN THE DEVELOPMENT OF CHRONIC OSTEOMYELITIS, AND THE MECHANISMS UNDERLYING THE DEVELOPMENT OF IMMUNE SUPPRESSION IN CHRONIC OSTEOMYELITIS HAVE ATTRACTED MUCH ATTENTION. LAG-3 IS AN IMPORTANT SUPPRESSOR OF T CELL ACTIVATION, BUT THE ROLE OF LAG-3 IN THE IMMUNE REGULATION OF CHRONIC OSTEOMYELITIS IS CURRENTLY UNKNOWN. WE SOUGHT TO DEMONSTRATE IF LAG-3 PLAYS CRUCIAL ROLES IN CHRONIC OSTEOMYELITIS PROGRESSION AND HAS EFFECTS ON IMMUNE SUPPRESSION AND EXHAUSTING OF T CELLS, AND WHAT IS THE MECHANISM UNDERLYING LAG-3 DEREGULATION IN CHRONIC OSTEOMYELITIS. WE EXAMINED THE EXPRESSION OF LAG-3 IN THE T CELLS OF PERIPHERAL BLOOD OF 50 HEALTHY CONTROLS AND 50 PATIENTS WITH CHRONIC OSTEOMYELITIS BY FLOW CYTOMETRY. CLINICAL DATA WERE ANALYZED TO DETERMINE THE CORRELATION BETWEEN INFLAMMATION INDEX AND LAG-3 EXPRESSION. MOREOVER, WE ISOLATED THE CD4(+) T CELLS FROM HEALTHY CONTROLS AND CHRONIC OSTEOMYELITIS PATIENTS TO COMPARE CELL PROLIFERATION AND IFN-GAMMA PRODUCTION. CHROMATIN IMMUNOPRECIPITATION ASSAYS WERE UTILIZED TO ANALYZE THE EPIGENETIC MODIFICATION ON LAG-3 EXPRESSION IN T CELLS. WE FOUND THAT LAG-3 WAS SIGNIFICANTLY INCREASED IN THE T CELLS OF PERIPHERAL BLOOD FROM CHRONIC OSTEOMYELITIS PATIENTS. SUBSEQUENTLY, CLINICAL DATA ANALYSIS SUGGESTED THAT THE HIGHER EXPRESSION OF LAG-3 WAS ASSOCIATED WITH SEVERER INFLAMMATION SITUATION. CONSISTENTLY, LAG-3(+)CD4(+) T CELLS EXHIBITED IMPAIRED CELL PROLIFERATION AND IFN-GAMMA SECRETION. DEREGULATION OF HISTONE METHYLATION MEDIATED THE INCREASE OF LAG-3(+) T CELLS DURING CHRONIC OSTEOMYELITIS. TAKEN TOGETHER, OUR STUDY DEMONSTRATES THE INCREASE OF LAG-3(+) T CELLS AND ITS IMMUNE REGULATORY ROLES IN CHRONIC OSTEOMYELITIS PROGRESSION, SUGGESTING NEW MECHANISMS AND POTENTIAL THERAPEUTIC TARGETS FOR CHRONIC OSTEOMYELITIS. 2017 2 1479 32 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 3 5223 36 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 4 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 5 2146 29 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 6 2764 32 EXPRESSION PATTERN, REGULATION, AND CLINICAL SIGNIFICANCE OF TOX IN BREAST CANCER. THYMOCYTE SELECTION-ASSOCIATED HIGH MOBILITY GROUP BOX PROTEIN (TOX) IS A TRANSCRIPTION FACTOR IMPLICATED IN THE REGULATION OF T CELL EXHAUSTION DURING CHRONIC INFECTION AND CANCER. WHILE TOX IS BEING TARGETED FOR CANCER IMMUNOTHERAPY, LIMITED INFORMATION IS AVAILABLE ABOUT ITS SIGNIFICANCE IN BREAST CANCER AND OTHER SOLID TUMORS. WE PERFORMED A COMPREHENSIVE ANALYSIS OF TOX GENE EXPRESSION, ITS EPIGENETIC REGULATION, PROTEIN LOCALIZATION, RELATION TO TUMOR INFILTRATING IMMUNE CELL COMPOSITION, AND PROGNOSTIC SIGNIFICANCE IN BREAST CANCER USING PUBLICLY AVAILABLE DATASETS. OUR RESULTS SUGGEST AN INVERSE CORRELATION BETWEEN TOX EXPRESSION AND DNA METHYLATION IN TUMOR CELLS. HOWEVER, ITS EXPRESSION IS ELEVATED IN TUMOR INFILTRATING IMMUNE CELLS (TIICS), WHICH MAY COMPENSATES FOR THE TOTAL TOX LEVELS IN THE TUMOR AS A WHOLE. FURTHERMORE, HIGHER TOX LEVELS IN TUMORS ARE ASSOCIATED WITH T CELL EXHAUSTION SIGNATURES ALONG WITH PRESENCE OF ACTIVE INFLAMMATORY RESPONSE, INCLUDING ELEVATED LEVELS OF T CELL EFFECTOR CYTOKINES. SURVIVAL ANALYSIS ALSO CONFIRMED THAT HIGHER EXPRESSION OF TOX IS ASSOCIATED WITH BETTER PROGNOSIS IN BREAST CANCER. THEREFORE, EXPRESSION OF TOX MAY SERVE AS A NOVEL PROGNOSTIC MARKER FOR THIS MALIGNANCY. 2021 7 2718 29 EXHAUSTED T CELLS AND EPIGENETIC STATUS. EXHAUSTED T CELLS ARE A GROUP OF DYSFUNCTIONAL T CELLS, WHICH ARE PRESENT IN CHRONIC INFECTIONS OR TUMORS. THE MOST SIGNIFICANT CHARACTERISTICS OF EXHAUSTED T CELLS ARE ATTENUATED EFFECTOR CYTOTOXICITY, REDUCED CYTOKINE PRODUCTION, AND UPREGULATION OF MULTIPLE INHIBITORY MOLECULAR RECEPTORS (E.G., PD-1, TIM-3, AND LAG-3). THE INTRACELLULAR METABOLIC CHANGES, ALTERED EXPRESSION OF TRANSCRIPTION FACTORS, AND A UNIQUE EPIGENETIC LANDSCAPE CONSTITUTE THE EXHAUSTION PROGRAM. RECENTLY, RESEARCHERS HAVE MADE PROGRESS IN UNDERSTANDING EXHAUSTED T CELLS, WITH THE DEFINITION AND IDENTIFICATION OF EXHAUSTED T CELLS CHANGING FROM PHENOTYPE-BASED TO BEING CLASSIFIED AT THE TRANSCRIPTIONAL AND EPIGENETIC LEVELS. RECENT STUDIES HAVE REVEALED THAT EXHAUSTED T CELLS CAN BE SEPARATED INTO TWO SUBGROUPS, NAMELY TCF1(+)PD-1(+) PROGENITOR-LIKE PRECURSOR EXHAUSTED CELLS AND TCF1(-)PD-1(+) TERMINALLY DIFFERENTIATED EXHAUSTED T CELLS. MOREOVER, THE PROGENITOR-LIKE PRECURSOR CELL POPULATION MAY BE A SUBSET OF T CELLS THAT CAN RESPOND TO IMMUNOTHERAPY. STUDIES HAVE ALSO FOUND THAT TOX INITIATES AND DOMINATES THE DEVELOPMENT OF EXHAUSTED T CELLS AT THE TRANSCRIPTIONAL AND EPIGENETIC LEVELS. TOX ALSO MAINTAINS T CELL SURVIVAL AND MAY AFFECT DECISIONS REGARDING TREATMENT STRATEGIES. IN THIS REVIEW, WE DISCUSS THE LATEST DEVELOPMENTS IN T CELL EXHAUSTION IN REGARDS TO DEFINITIONS, SUBPOPULATIONS, DEVELOPMENT MECHANISMS, DIFFERENCES IN DIVERSE DISEASES, AND TREATMENT PROSPECTS FOR EXHAUSTED T CELLS. FURTHERMORE, WE HYPOTHESIZE THAT THE EPIGENETIC STATE REGULATED BY TOX MIGHT BE THE KEY POINT, WHICH CAN DETERMINE THE REVERSIBILITY OF EXHAUSTION AND THE EFFICACY OF IMMUNOTHERAPY. 2020 8 855 35 CHROMATIN ACCESSIBILITY LANDSCAPES OF IMMUNE CELLS IN RHEUMATOID ARTHRITIS NOMINATE MONOCYTES IN DISEASE PATHOGENESIS. BACKGROUND: RHEUMATOID ARTHRITIS (RA) IS A CHRONIC, SYSTEMIC AUTOIMMUNE DISEASE THAT INVOLVES A VARIETY OF CELL TYPES. HOWEVER, HOW THE EPIGENETIC DYSREGULATIONS OF PERIPHERAL IMMUNE CELLS CONTRIBUTE TO THE PATHOGENESIS OF RA STILL REMAINS LARGELY UNCLEAR. RESULTS: HERE, WE ANALYSED THE GENOME-WIDE ACTIVE DNA REGULATORY ELEMENTS OF FOUR MAJOR IMMUNE CELLS, NAMELY MONOCYTES, B CELLS, CD4(+) T CELLS AND CD8(+) T CELLS, IN PERIPHERAL BLOOD OF RA PATIENTS, OSTEOARTHRITIS (OA) PATIENTS AND HEALTHY DONORS USING ASSAY OF TRANSPOSASE ACCESSIBLE CHROMATIN WITH SEQUENCING (ATAC-SEQ). WE FOUND A STRONG RA-ASSOCIATED CHROMATIN DYSREGULATION SIGNATURE IN MONOCYTES, BUT NO OTHER EXAMINED CELL TYPES. MOREOVER, WE FOUND THAT SERUM C-REACTIVE PROTEIN (CRP) CAN INDUCE THE RA-ASSOCIATED CHROMATIN DYSREGULATION IN MONOCYTES VIA IN VITRO EXPERIMENTS. AND THE EXTENT OF THIS DYSREGULATION WAS REGULATED THROUGH THE TRANSCRIPTION FACTOR FRA2. CONCLUSIONS: TOGETHER, OUR STUDY REVEALED A CRP-INDUCED PATHOGENIC CHROMATIN DYSREGULATION SIGNATURE IN MONOCYTES FROM RA PATIENTS AND PREDICTED THE RESPONSIBLE SIGNALLING PATHWAY AS POTENTIAL THERAPEUTIC TARGETS FOR THE DISEASE. 2021 9 1319 34 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 10 451 33 APPLICATION OF ATAC-SEQ IN TUMOR-SPECIFIC T CELL EXHAUSTION. RESEARCHES SHOW THAT CHRONIC VIRAL INFECTION AND PERSISTENT ANTIGEN AND/OR INFLAMMATORY SIGNAL EXPOSURE IN CANCER CAUSES THE FUNCTIONAL STATUS OF T CELLS TO BE ALTERED, MAINLY BY MAJOR CHANGES IN THE EPIGENETIC AND METABOLIC ENVIRONMENT, WHICH THEN LEADS TO T CELL EXHAUSTION. THE DISCOVERY OF THE IMMUNE CHECKPOINT PATHWAY IS AN IMPORTANT MILESTONE IN UNDERSTANDING AND REVERSING T CELL EXHAUSTION. ANTIBODIES TARGETING THESE PATHWAYS HAVE SHOWN SUPERIOR ABILITY TO REVERSE T CELL EXHAUSTION. HOWEVER, THERE ARE STILL SOME LIMITATIONS IN IMMUNE CHECKPOINT BLOCKING THERAPY, SUCH AS THE SHORT-TERM NATURE OF THERAPEUTIC EFFECTS AND HIGH INDIVIDUAL HETEROGENEITY. ASSAY FOR TRANSPOSASE-ACCESSIBLE CHROMATIN WITH SEQUENCING(ATAC-SEQ) IS A METHOD USED TO ANALYZE THE ACCESSIBILITY OF WHOLE-GENOME CHROMATIN. IT USES HYPERACTIVE TN5 TRANSPOSASE TO ASSESS CHROMATIN ACCESSIBILITY. RECENTLY, A GROWING NUMBER OF STUDIES HAVE REPORTED THAT ATAC-SEQ CAN BE USED TO CHARACTERIZE THE DYNAMIC CHANGES OF EPIGENETICS IN THE PROCESS OF T CELL EXHAUSTION. IT HAS BEEN DETERMINED THAT IMMUNE CHECKPOINT BLOCKING CAN ONLY TEMPORARILY RESTORE THE FUNCTION OF EXHAUSTED T CELLS BECAUSE OF AN IRREVERSIBLE CHANGE IN THE EPIGENETICS OF EXHAUSTED T CELLS. IN THIS STUDY, WE REVIEW THE LATEST DEVELOPMENTS, WHICH PROVIDE A CLEARER MOLECULAR UNDERSTANDING OF T CELL EXHAUSTION, REVEAL POTENTIAL NEW THERAPEUTIC TARGETS FOR PERSISTENT VIRAL INFECTION AND CANCER, AND PROVIDE NEW INSIGHTS FOR DESIGNING EFFECTIVE IMMUNOTHERAPY FOR TREATING CANCER AND CHRONIC INFECTION. 2023 11 6293 31 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 12 5058 41 PHENOTYPIC ALTERATION OF CD8+ T CELLS IN CHRONIC LYMPHOCYTIC LEUKEMIA IS ASSOCIATED WITH EPIGENETIC REPROGRAMMING. IMMUNOSUPPRESSION IS A PREVALENT CLINICAL FEATURE IN CHRONIC LYMPHOCYTIC LEUKEMIA (CLL) PATIENTS, WITH MANY PATIENTS DEMONSTRATING INCREASED SUSCEPTIBILITY TO INFECTIONS AS WELL AS INCREASED FAILURE OF AN ANTITUMOR IMMUNE RESPONSE. HOWEVER, MUCH IS CURRENTLY NOT UNDERSTOOD REGARDING THE PRECISE MECHANISMS THAT ATTRIBUTE TO THIS IMMUNOSUPPRESSIVE PHENOTYPE IN CLL. TO PROVIDE FURTHER CLARITY TO THIS PARTICULAR PHENOMENON, WE ANALYZED THE T-CELL PROFILE OF CLL PATIENT SAMPLES WITHIN A LARGE COHORT AND OBSERVED THAT PATIENTS WITH AN INVERTED CD4/CD8 RATIO HAD A SHORTER TIME TO FIRST TREATMENT AS WELL AS OVERALL SURVIVAL. THESE OBSERVATIONS COINCIDED WITH HIGHER EXPRESSION OF THE IMMUNE CHECKPOINT RECEPTOR PD-1 IN CLL PATIENT CD8+ T CELLS WHEN COMPARED TO AGE-MATCHED HEALTHY DONORS. INTERESTINGLY, WE DISCOVERED THAT INCREASED PD-1 EXPRESSION IN CD8+ T CELLS CORRESPONDS WITH DECREASED DNA METHYLATION LEVELS IN A DISTAL UPSTREAM LOCUS OF THE PD-1 GENE PDCD1. FURTHER ANALYSIS USING LUCIFERASE REPORTER ASSAYS SUGGESTS THAT THE IDENTIFIED PDCD1 DISTAL UPSTREAM REGION ACTS AS AN ENHANCER FOR PDCD1 TRANSCRIPTION AND THIS REGION BECOMES DEMETHYLATED DURING ACTIVATION OF NAIVE CD8+ T CELLS BY ANTI-CD3/ANTI-CD28 ANTIBODIES AND IL2. FINALLY, WE CONDUCTED A GENOME-WIDE DNA METHYLATION ANALYSIS COMPARING CD8+ T CELLS FROM CLL PATIENTS AGAINST HEALTHY DONORS AND IDENTIFIED ADDITIONAL DIFFERENTIALLY METHYLATED GENES WITH KNOWN IMMUNE REGULATORY FUNCTIONS INCLUDING CCR6 AND KLRG1. TAKEN TOGETHER, OUR FINDINGS REVEAL THE OCCURRENCE OF EPIGENETIC REPROGRAMMING TAKING PLACE WITHIN CLL PATIENT CD8+ T CELLS AND HIGHLIGHT THE POTENTIAL MECHANISM OF HOW IMMUNOSUPPRESSION IS ACCOMPLISHED IN CLL. 2016 13 1500 41 DNA METHYLATION ANALYSIS OF CD4+ T CELLS IN PATIENTS WITH PSORIASIS. PSORIASIS IS A CHRONIC INFLAMMATORY SKIN DISEASE THAT IS CHARACTERIZED BY ABERRANT CROSS-TALK BETWEEN KERATINOCYTES AND IMMUNE CELLS SUCH AS CD4+ T CELLS, RESULTING IN KERATINOCYTE HYPERPROLIFERATION IN THE EPIDERMIS. DNA METHYLATION, ONE OF SEVERAL EPIGENETIC MECHANISMS, PLAYS AN IMPORTANT ROLE IN GENE EXPRESSION WITHOUT CHANGING THE DNA SEQUENCE. SEVERAL STUDIES HAVE SUGGESTED THE INVOLVEMENT OF EPIGENETIC REGULATION IN SKIN LESIONS FROM PATIENTS WITH PSORIASIS. IN THIS STUDY, WE INVESTIGATED THE GENOME-WIDE DNA METHYLATION STATUS OF CD4+ T CELLS IN PATIENTS WITH PSORIASIS COMPARED WITH HEALTHY SUBJECTS USING METHYLATED DNA IMMUNOPRECIPITATION SEQUENCING (MEDIP-SEQ). THE RESULTS OF MEDIP-SEQ SHOWED THAT THE GLOBAL METHYLATION VALUES OF CD4+ T CELLS ARE HIGHER IN PATIENTS WITH PSORIASIS THAN IN HEALTHY CONTROLS, PARTICULARLY IN THE PROMOTER REGIONS. AMONG THE MOST HYPERMETHYLATED GENES IN THE PROMOTER REGIONS, WE SELECTED THE GENES WHOSE EXPRESSION IS SIGNIFICANTLY REDUCED IN THE CD4+ T CELLS OF PSORIASIS PATIENTS. STUDIES USING THE METHYLATION INHIBITOR 5-AZACYTIDINE IN VITRO METHYLATION ASSAYS HAVE SHOWN THAT THE DIFFERENTIAL EXPRESSION LEVELS WERE ASSOCIATED WITH THE METHYLATION STATUS OF EACH GENE. BISULFITE SEQUENCING OF THE TRANSCRIPTION START REGION OF PHOSPHATIDIC ACID PHOSPHATASE TYPE 2 DOMAIN CONTAINING 3 (PPAPDC3), ONE OF THE SELECTED GENES, SHOWED HYPERMETHYLATION IN THE CD4+ T CELLS OF PSORIASIS PATIENTS. THESE RESULTS SUGGESTED THAT THE METHYLATION STATUS, WHICH IS IDENTIFIED BY MEDIP-SEQ OF THE GENES, WAS CORRELATED WITH THE MRNA EXPRESSION LEVEL OF THE GENES. COLLECTIVELY, THE DNA METHYLATION STATUS IN CD4+ T CELLS MIGHT BE ASSOCIATED WITH THE PATHOGENESIS OF PSORIASIS. 2014 14 6677 25 USING EPIGENETICS TO DEFINE VACCINE-INDUCED MEMORY T CELLS. MEMORY T CELLS GENERATED FROM ACUTE INFECTION OR VACCINATION HAVE THE POTENTIAL TO PROVIDE THE HOST WITH LIFE-LONG IMMUNITY AGAINST RE-INFECTION. PROTECTION BY MEMORY T CELLS IS ACHIEVED THROUGH THEIR ACQUIRED ABILITY TO PERSIST AT ANATOMICAL SITES OF THE PRIMARY INFECTION AS WELL AS MAINTAINING A HEIGHTENED ABILITY TO RECALL EFFECTOR FUNCTIONS. THE MAINTENANCE OF CD8 AND CD4 T CELL FUNCTION IN A STATE OF READINESS IS KEY TO LIFE-LONG IMMUNITY AND MANIFEST THROUGH CHANGES IN TRANSCRIPTIONAL REGULATION. YET, THE ABILITY TO IDENTIFY POISED TRANSCRIPTIONAL PROGRAMS AT THE MAINTENANCE STAGE OF THE RESPONSE IS LACKING FROM MOST TRANSCRIPTIONAL PROFILING STUDIES OF MEMORY T CELLS. EPIGENETIC PROFILING ALLOWS FOR THE ASSESSMENT OF TRANSCRIPTIONALLY POISED (PROMOTERS THAT ARE READILY ACCESSIBLE FOR TRANSCRIPTION) STATES OF ANTIGEN-SPECIFIC T CELLS WITHOUT MANIPULATION OF THE ACTIVATION STATE OF THE CELL. HERE WE REVIEW RECENT STUDIES THAT HAVE EXAMINED EPIGENETIC PROGRAMS OF EFFECTOR AND MEMORY T CELL SUBSETS. THESE REPORTS DEMONSTRATE THAT ACQUISITION OF EPIGENETIC PROGRAMS DURING MEMORY T CELL DIFFERENTIATION TO ACUTE AND CHRONIC INFECTIONS IS COUPLED TO, AND POTENTIALLY REGULATE, THE CELL'S RECALL RESPONSE. WE DISCUSS THE USEFULNESS OF EPIGENETIC PROFILING IN CHARACTERIZING T CELL DIFFERENTIATION STATE AND FUNCTION FOR PRECLINICAL EVALUATION OF VACCINES AND THE CURRENT METHODOLOGIES FOR SINGLE LOCUS VERSUS GENOME-WIDE EPIGENETIC PROFILING. 2013 15 6530 29 TRANSCRIPTIONAL REGULATION AND T CELL EXHAUSTION. PURPOSE OF REVIEW: THIS REVIEW HIGHLIGHTS THE CONTROL OF TRANSCRIPTIONAL NETWORKS, INCLUDING INDUCTION OF INHIBITORY RECEPTORS, BY T CELL-SPECIFIC TRANSCRIPTION FACTORS IN EXHAUSTED T CELLS THAT ACCUMULATE IN CHRONIC VIRAL INFECTIONS INCLUDING HIV. RECENT FINDINGS: TRANSCRIPTIONAL PROFILING HAS ESTABLISHED DISTINCT MOLECULAR PHENOTYPES FOR EXHAUSTED CD4 AND CD8 T CELLS IN CHRONIC VIRAL INFECTION MODELS. THERE EXISTS A SUBSET OF TRANSCRIPTION FACTORS ASSOCIATED WITH EXHAUSTION, NOTABLY BLIMP-1, BASIC LEUCINE ZIPPER TRANSCRIPTION FACTOR, ATF-LIKE AND HELIOS. EPIGENETIC PHENOMENA ARE LIKELY IMPORTANT IN REGULATING GENE EXPRESSION NETWORKS DURING EXHAUSTION AS ILLUSTRATED BY PROGRAMMED DEATH 1 PROMOTER METHYLATION PATTERNS. SUMMARY: FOLLOWING CHRONIC VIRAL INFECTIONS, CD4 AND CD8 T CELLS DEFINED FUNCTIONALLY AND PHENOTYPICALLY AS EXHAUSTED HAVE DISTINCT TRANSCRIPTIONAL PROFILES. THESE STUDIES HAVE IDENTIFIED A CORE SET OF TRANSCRIPTION FACTORS THAT HAVE BEEN IMPLICATED IN PROMOTING EXHAUSTION. HOWEVER, NO SINGLE FACTOR APPEARS TO BE AN EXHAUSTION DETERMINING FACTOR, SUGGESTING THAT T CELL EXHAUSTION REFLECTS A COMBINATORIAL MECHANISM WITH MULTIPLE TRANSCRIPTION FACTORS INTERACTING TO INFLUENCE THE DEVELOPMENT OF FUNCTIONALLY EXHAUSTED T CELLS AS WELL AS DIFFERENT T EFFECTOR POPULATIONS. 2014 16 1711 30 DYSFUNCTIONAL STATE OF T CELLS OR EXHAUSTION DURING CHRONIC VIRAL INFECTIONS AND COVID-19: A REVIEW. CORONAVIRUS DISEASE 2019 (COVID-19) CONTINUOUSLY AFFECTING THE LIVES OF MILLIONS OF PEOPLE. THE VIRUS IS SPREAD THROUGH THE RESPIRATORY ROUTE TO AN UNINFECTED PERSON, CAUSING MILD-TO-MODERATE RESPIRATORY DISEASE-LIKE SYMPTOMS THAT SOMETIMES PROGRESS TO SEVERE FORM AND CAN BE FATAL. WHEN THE HOST IS INFECTED WITH THE VIRUS, BOTH INNATE AND ADAPTIVE IMMUNITY COMES INTO PLAY. THE EFFECTOR T CELLS ACT AS THE MASTER PLAYER OF ADAPTIVE IMMUNE RESPONSE IN ERADICATING THE VIRUS FROM THE SYSTEM. BUT DURING CANCER AND CHRONIC VIRAL INFECTIONS, THE FATE OF AN EFFECTOR T CELL IS ALTERED, AND THE T CELL MAY ENTERS A STATE OF EXHAUSTION, WHICH IS MARKED BY LOSS OF EFFECTOR FUNCTION, DEPLETED PROLIFERATIVE CAPACITY AND CYTOTOXIC EFFECT ACCOMPLISHED BY AN INCREASED EXPRESSION OF NUMEROUS INHIBITORY RECEPTORS SUCH AS PROGRAMMED CELL DEATH PROTEIN 1 (PD-1), LYMPHOCYTE-ACTIVATION PROTEIN 3 (LAG-3), AND CYTOTOXIC T LYMPHOCYTE-ASSOCIATED ANTIGEN 4 (CTLA-4) ON THEIR SURFACE. VARIOUS OTHER TRANSCRIPTIONAL AND EPIGENETIC CHANGES TAKE PLACE INSIDE THE T CELL WHEN IT ENTERS INTO AN EXHAUSTED STATE. LATEST STUDIES POINT TOWARD THE INDUCTION OF AN ABNORMAL IMMUNE RESPONSE SUCH AS LYMPHOPENIA, CYTOKINE STORM, AND T CELL EXHAUSTION DURING SARS-COV-2 (SEVERE ACUTE RESPIRATORY SYNDROME CORONAVIRUS 2) INFECTION. THIS REVIEW SHEDS LIGHT ON THE DYSFUNCTIONAL STATE OF T CELLS DURING CHRONIC VIRAL INFECTION AND COVID-19. UNDERSTANDING THE CAUSE AND THE EFFECT OF T CELL EXHAUSTION OBSERVED DURING COVID-19 MAY HELP RESOLVE NEW THERAPEUTIC POTENTIALS FOR TREATING CHRONIC INFECTIONS AND OTHER DISEASES. 2022 17 2036 24 EPIGENETIC CHANGES OF THE IMMUNE SYSTEM WITH ROLE IN TUMOR DEVELOPMENT. TUMOR DEVELOPMENT IS CLOSELY RELATED TO CHRONIC INFLAMMATION AND TO EVASION OF IMMUNE DEFENSE MECHANISMS BY NEOPLASTIC CELLS. THE MEDIATORS OF THE INFLAMMATORY PROCESS AS WELL AS PROTEINS INVOLVED IN IMMUNE RESPONSE OR IMMUNE RESPONSE EVASION CAN BE SUBJECT TO VARIOUS EPIGENETIC CHANGES SUCH AS METHYLATION, ACETYLATION, OR PHOSPHORYLATION. SOME OF THESE, SUCH AS CYTOKINE SUPPRESSORS, ARE UNDERGOING REPRESSION THROUGH EPIGENETIC CHANGES, AND OTHERS SUCH AS CYTOKINES OR CHEMOKINES ARE UNDERGOING ACTIVATION THROUGH EPIGENETIC CHANGES, BOTH MODIFICATIONS HAVING AS A RESULT TUMOR PROGRESSION. THE ACTIVATING CHANGES CAN AFFECT THE RECEPTOR MOLECULES INVOLVED IN IMMUNE RESPONSE AND THESE PROMOTE INFLAMMATION AND SUBSEQUENTLY TUMOR DEVELOPMENT WHILE THE INACTIVATING CHANGES SEEM TO BE RELATED TO THE TUMOR REGRESSION PROCESS. THE PROTEINS INVOLVED IN ANTIGEN PRESENTATION, AND, THEREFORE IN IMMUNE RESPONSE ESCAPE, SUCH AS CLASSICAL HLA PROTEINS AND RELATED APM (ANTIGEN PRESENTATION MACHINERY) WITH THEIR EPIGENETIC CHANGES CONTRIBUTE TO THE TUMOR DEVELOPMENT PROCESS, EITHER TO TUMOR PROGRESSION OR REGRESSION, DEPENDING ON THE IMMUNE EFFECTOR CELLS THAT ARE IN PLAY. 2018 18 6851 30 [MOLECULAR PROFILES OF EXHAUSTED T CELLS AND THEIR IMPACT ON RESPONSE TO IMMUNE CHECKPOINT BLOCKADE]. T CELL EXHAUSTION IS INDUCED IN THE CONTEXT OF CHRONIC VIRUS INFECTION AND TUMOR MICROENVIRONMENT, IN WHICH CYTOTOXIC T CELLS ARE REPEATEDLY EXPOSED TO THE TARGET ANTIGEN AND DEPRIVED OF THEIR EFFECTOR FUNCTIONS. MULTIPLE STUDIES HAVE ALREADY SHOWN THE SIGNIFICANT IMPACT OF IMMUNE CHECKPOINT MOLECULES SUCH AS PD1 ON FUNCTIONAL PROPERTIES OF EXHAUSTED T CELLS. IN ADDITION TO THESE SIGNALS, EXHAUSTED T CELLS POSSESS DISTINCT TRANSCRIPTIONAL AND EPIGENETIC PROFILES COMPARED WITH CONVENTIONAL EFFECTOR AND MEMORY T CELLS. IMPORTANTLY, MOST OF THESE FEATURES ARE NOT AFFECTED BY IMMUNE CHECKPOINT BLOCKADE, SUGGESTING THAT GENETIC AND EPIGENETIC REMODELING OF T CELLS IS AN UNDERLYING MOLECULAR MECHANISM ESSENTIAL FOR T CELL EXHAUSTION. MOREOVER, IT HAS NOW BEEN EVIDENT THAT EXHAUSTED T CELLS ARE A HETEROGENEOUS CELL POPULATION COMPOSED OF DISTINCT T CELL SUBSETS, AND THESE FUNCTIONAL DIFFERENCES PROFOUNDLY AFFECT THERAPEUTIC EFFICACY OF CANCER IMMUNOTHERAPY. IN THIS REVIEW, I WILL DISCUSS RECENT STUDIES INVESTIGATING MOLECULAR MECHANISMS OF T CELL EXHAUSTION, INCLUDING NOVEL KEY MOLECULES ESSENTIALLY ASSOCIATED WITH T CELL EXHAUSTION. THESE FINDINGS ARE POTENTIALLY APPLICABLE TO REINVIGORATE EFFECTOR FUNCTIONS OF EXHAUSTED T CELLS. 2022 19 6535 29 TRANSCRIPTIONAL REGULATION OF THE ANTI-INFLAMMATORY CYTOKINE IL-10 IN ACQUIRED IMMUNE CELLS. ALTHOUGH THE MAJOR ROLE OF THE IMMUNE RESPONSE IS HOST DEFENSE FROM A WIDE RANGE OF POTENTIALLY PATHOGENIC MICROORGANISMS, EXCESS IMMUNE RESPONSES CAN RESULT IN SEVERE HOST DAMAGE. THE HOST THUS REQUIRES ANTI-INFLAMMATORY MECHANISMS TO PREVENT REACTIVITY TO SELF. INTERLEUKIN-10 (IL-10) IS A CYTOKINE WITH BROAD ANTI-INFLAMMATORY PROPERTIES INVOLVED IN THE PATHOGENESIS OF VARIOUS DISEASES. IL-10 WAS ORIGINALLY DESCRIBED AS A T HELPER (T(H)2) DERIVED CYTOKINE, BUT FURTHER STUDIES INDICATED THAT IL-10 IS EXPRESSED NOT ONLY BY MANY CELLS OF THE ADAPTIVE IMMUNE SYSTEM, INCLUDING T AND B CELLS, BUT ALSO BY THE INNATE IMMUNE CELLS, INCLUDING DENDRITIC CELLS (DCS), MACROPHAGES, MAST CELLS, AND NATURAL KILLER (NK) CELLS. IN ADDITION, IL-10 CAN BE INDUCED IN T(H)1 AND T(H)17 CELLS BY CHRONIC INFLAMMATION AS A SYSTEM OF FEEDBACK REGULATION. IN THIS REVIEW, WE FOCUS ON THE MOLECULAR MECHANISMS UNDERLYING IL10 GENE EXPRESSION IN ADAPTIVE IMMUNE CELLS AND SUMMARIZE THE RECENT PROGRESSES IN EPIGENETIC AND TRANSCRIPTIONAL REGULATION OF THE IL10 GENE. UNDERSTANDING THE TRANSCRIPTIONAL REGULATORY EVENTS MAY HELP IN THE DEVELOPMENT OF NEW STRATEGIES TO CONTROL INFLAMMATORY DISEASES. 2012 20 1357 35 DEVELOPMENT OF INNATE IMMUNE MEMORY BY NON-IMMUNE CELLS DURING STAPHYLOCOCCUS AUREUS INFECTION DEPENDS ON REACTIVE OXYGEN SPECIES. INTRODUCTION: THE MECHANISMS UNDERLYING INNATE IMMUNE MEMORY (TRAINED IMMUNITY) COMPRISE EPIGENETIC REPROGRAMMING OF TRANSCRIPTIONAL PATHWAYS ASSOCIATED WITH ALTERATIONS OF INTRACELLULAR METABOLISM. WHILE THE MECHANISMS OF INNATE IMMUNE MEMORY CARRIED OUT BY IMMUNE CELLS ARE WELL CHARACTERIZED, SUCH PROCESSES IN NON-IMMUNE CELLS, ARE POORLY UNDERSTOOD. THE OPPORTUNISTIC PATHOGEN, STAPHYLOCOCCUS AUREUS, IS RESPONSIBLE FOR A MULTITUDE OF HUMAN DISEASES, INCLUDING PNEUMONIA, ENDOCARDITIS AND OSTEOMYELITIS, AS WELL AS ANIMAL INFECTIONS, INCLUDING CHRONIC CATTLE MASTITIS THAT ARE EXTREMELY DIFFICULT TO TREAT. AN INDUCTION OF INNATE IMMUNE MEMORY MAY BE CONSIDERED AS A THERAPEUTIC ALTERNATIVE TO FIGHT S. AUREUS INFECTION. METHODS: IN THE CURRENT WORK, WE DEMONSTRATED THE DEVELOPMENT OF INNATE IMMUNE MEMORY IN NON-IMMUNE CELLS DURING S. AUREUS INFECTION EMPLOYING A COMBINATION OF TECHNIQUES INCLUDING ENZYME-LINKED IMMUNOSORBENT ASSAY (ELISA), MICROSCOPIC ANALYSIS, AND CYTOMETRY. RESULTS: WE OBSERVED THAT TRAINING OF HUMAN OSTEOBLAST-LIKE MG-63 CELLS AND LUNG EPITHELIAL A549 CELLS WITH BETA-GLUCAN INCREASED IL-6 AND IL-8 PRODUCTION UPON A STIMULATION WITH S. AUREUS, CONCOMITANT WITH HISTONES MODIFICATIONS. IL-6 AND IL-8 PRODUCTION WAS POSITIVELY CORRELATED WITH AN ACETYLATION OF HISTONE 3 AT LYSINE 27 (H3K27), THUS SUGGESTING EPIGENETIC REPROGRAMMING IN THESE CELLS. AN ADDITION OF THE ROS SCAVENGER N-ACETYLCYSTEINE, NAC, PRIOR TO BETA-GLUCAN PRETREATMENT FOLLOWED BY AN EXPOSURE TO S. AUREUS, RESULTED IN DECREASED IL-6 AND IL-8 PRODUCTION, THEREBY SUPPORTING THE INVOLVEMENT OF ROS IN THE INDUCTION OF INNATE IMMUNE MEMORY. EXPOSURE OF CELLS TO LACTOCOCCUS LACTIS RESULTED IN INCREASED IL-6 AND IL-8 PRODUCTION BY MG-63 AND A549 CELLS UPON A STIMULATION WITH S. AUREUS THAT WAS CORRELATED WITH H3K27 ACETYLATION, SUGGESTING THE ABILITY OF THIS BENEFICIAL BACTERIUM TO INDUCE INNATE IMMUNE MEMORY. DISCUSSION: THIS WORK IMPROVES OUR UNDERSTANDING OF INNATE IMMUNE MEMORY IN NON-IMMUNE CELLS IN THE CONTEXT OF S. AUREUS INFECTION. IN ADDITION TO KNOWN INDUCERS, PROBIOTICS MAY REPRESENT GOOD CANDIDATES FOR THE INDUCTION OF INNATE IMMUNE MEMORY. OUR FINDINGS MAY HELP THE DEVELOPMENT OF ALTERNATIVE THERAPEUTIC APPROACHES FOR THE PREVENTION OF S. AUREUS INFECTION. 2023