1 6496 174 TRAINED IMMUNITY CONTRIBUTION TO AUTOIMMUNE AND INFLAMMATORY DISORDERS. A DYSREGULATED IMMUNE RESPONSE TOWARD SELF-ANTIGENS CHARACTERIZES AUTOIMMUNE AND AUTOINFLAMMATORY (AIF) DISORDERS. AUTOANTIBODIES OR AUTOREACTIVE T CELLS CONTRIBUTE TO AUTOIMMUNE DISEASES, WHILE AUTOINFLAMMATION RESULTS FROM A HYPER-FUNCTIONAL INNATE IMMUNE SYSTEM. ASIDE FROM THEIR DIFFERENCES, MANY STUDIES SUGGEST THAT MONOCYTES AND MACROPHAGES (MO/MA) SIGNIFICANTLY CONTRIBUTE TO THE DEVELOPMENT OF BOTH TYPES OF DISEASE. MO/MA ARE INNATE IMMUNE CELLS THAT PROMOTE AN IMMUNE-MODULATORY, PRO-INFLAMMATORY, OR REPAIR RESPONSE DEPENDING ON THE MICROENVIRONMENT. HOWEVER, UNDERSTANDING THE CONTRIBUTION OF THESE CELLS TO DIFFERENT IMMUNE DISORDERS HAS BEEN DIFFICULT DUE TO THEIR HIGH FUNCTIONAL AND PHENOTYPIC PLASTICITY. SEVERAL FACTORS CAN INFLUENCE THE FUNCTION OF MO/MA UNDER THE LANDSCAPE OF AUTOIMMUNE/AUTOINFLAMMATORY DISEASES, SUCH AS GENETIC PREDISPOSITION, EPIGENETIC CHANGES, OR INFECTIONS. FOR INSTANCE, SOME VACCINES AND MICROORGANISMS CAN INDUCE EPIGENETIC CHANGES IN MO/MA, MODIFYING THEIR FUNCTIONAL RESPONSES. THIS PHENOMENON IS KNOWN AS TRAINED IMMUNITY. TRAINED IMMUNITY CAN BE MEDIATED BY MO/MA AND NK CELLS INDEPENDENTLY OF T AND B CELL FUNCTION. IT IS DEFINED AS THE ALTERED INNATE IMMUNE RESPONSE TO THE SAME OR DIFFERENT MICROORGANISMS DURING A SECOND ENCOUNTER. THE IMPROVEMENT IN CELL FUNCTION IS RELATED TO EPIGENETIC AND METABOLIC CHANGES THAT MODIFY GENE EXPRESSION. ALTHOUGH THE BENEFITS OF IMMUNE TRAINING HAVE BEEN HIGHLIGHTED IN A VACCINATION CONTEXT, THE EFFECTS OF THIS TYPE OF IMMUNE RESPONSE ON AUTOIMMUNITY AND CHRONIC INFLAMMATION STILL REMAIN CONTROVERSIAL. INDUCTION OF TRAINED IMMUNITY REPROGRAMS CELLULAR METABOLISM IN HEMATOPOIETIC STEM CELLS (HSCS), TRANSMITTING A MEMORY-LIKE PHENOTYPE TO THE CELLS. THUS, TRAINED MO/MA DERIVED FROM HSCS TYPICALLY PRESENT A METABOLIC SHIFT TOWARD GLYCOLYSIS, WHICH LEADS TO THE MODIFICATION OF THE CHROMATIN ARCHITECTURE. DURING TRAINED IMMUNITY, THE EPIGENETIC CHANGES FACILITATE THE SPECIFIC GENE EXPRESSION AFTER SECONDARY CHALLENGE WITH OTHER STIMULI. CONSEQUENTLY, THE ENHANCED PRO-INFLAMMATORY RESPONSE COULD CONTRIBUTE TO DEVELOPING OR MAINTAINING AUTOIMMUNE/AUTOINFLAMMATORY DISEASES. HOWEVER, THE PREDICTION OF THE OUTCOME IS NOT SIMPLE, AND OTHER STUDIES PROPOSE THAT TRAINED IMMUNITY CAN INDUCE A BENEFICIAL RESPONSE BOTH IN AIF AND AUTOIMMUNE CONDITIONS BY INDUCING ANTI-INFLAMMATORY RESPONSES. THIS ARTICLE DESCRIBES THE METABOLIC AND EPIGENETIC MECHANISMS INVOLVED IN TRAINED IMMUNITY THAT AFFECT MO/MA, CONTRAPOSING THE CONTROVERSIAL EVIDENCE ON HOW IT MAY IMPACT AUTOIMMUNE/AUTOINFLAMMATION CONDITIONS. 2022 2 6506 43 TRAINED INNATE IMMUNITY NOT ALWAYS AMICABLE. THE CONCEPT OF „TRAINED INNATE IMMUNITY" IS UNDERSTOOD AS THE ABILITY OF INNATE IMMUNE CELLS TO REMEMBER INVADING AGENTS AND TO RESPOND NONSPECIFICALLY TO REINFECTION WITH INCREASED STRENGTH. TRAINED IMMUNITY IS ORCHESTRATED BY EPIGENETIC MODIFICATIONS LEADING TO CHANGES IN GENE EXPRESSION AND CELL PHYSIOLOGY. ALTHOUGH THIS PHENOMENON WAS ORIGINALLY SEEN MAINLY AS A BENEFICIAL EFFECT, SINCE IT CONFERS BROAD IMMUNOLOGICAL PROTECTION, ENHANCED IMMUNE RESPONSE OF REPROGRAMMED INNATE IMMUNE CELLS MIGHT RESULT IN THE DEVELOPMENT OR PERSISTENCE OF CHRONIC METABOLIC, AUTOIMMUNE OR NEUROINFALMMATORY DISORDERS. THIS PAPER OVERVIEWS SEVERAL EXAMPLES WHERE THE INDUCTION OF TRAINED IMMUNITY MAY BE ESSENTIAL IN THE DEVELOPMENT OF DISEASES CHARACTERIZED BY FLAWED INNATE IMMUNE RESPONSE. 2019 3 3733 43 INNATE IMMUNE MEMORY IN INFLAMMATORY ARTHRITIS. THE CONCEPT OF IMMUNOLOGICAL MEMORY WAS DEMONSTRATED IN ANTIQUITY WHEN PROTECTION AGAINST RE-EXPOSURE TO PATHOGENS WAS OBSERVED DURING THE PLAGUE OF ATHENS. IMMUNOLOGICAL MEMORY HAS BEEN LINKED WITH THE ADAPTIVE FEATURES OF T AND B CELLS; HOWEVER, IN THE PAST DECADE, EVIDENCE HAS DEMONSTRATED THAT INNATE IMMUNE CELLS CAN EXHIBIT MEMORY, A PHENOMENON CALLED 'INNATE IMMUNE MEMORY' OR 'TRAINED IMMUNITY'. INNATE IMMUNE MEMORY IS CURRENTLY BEING DEFINED AND IS TRANSFORMING OUR UNDERSTANDING OF CHRONIC INFLAMMATION AND AUTOIMMUNITY. IN THIS REVIEW, WE PROVIDE AN UP-TO-DATE OVERVIEW OF THE MEMORY-LIKE FEATURES OF INNATE IMMUNE CELLS IN INFLAMMATORY ARTHRITIS AND THE CROSSTALK BETWEEN CHRONIC INFLAMMATORY MILIEU AND CELL REPROGRAMMING. ABERRANT PRO-INFLAMMATORY SIGNALLING, INCLUDING CYTOKINES, REGULATES THE METABOLIC AND EPIGENETIC REPROGRAMMING OF HAEMATOPOIETIC PROGENITORS, LEADING TO EXACERBATED INFLAMMATORY RESPONSES AND OSTEOCLAST DIFFERENTIATION, IN TURN LEADING TO BONE DESTRUCTION. MOREOVER, IMPRINTED MEMORY ON MATURE CELLS INCLUDING TERMINALLY DIFFERENTIATED OSTEOCLASTS ALTERS RESPONSIVENESS TO THERAPIES AND MODIFIES DISEASE OUTCOMES, COMMONLY MANIFESTED BY PERSISTENT INFLAMMATORY FLARES AND RELAPSE FOLLOWING MEDICATION WITHDRAWAL. 2023 4 6255 41 THE MICROBIOTA AND EPIGENETIC REGULATION OF T HELPER 17/REGULATORY T CELLS: IN SEARCH OF A BALANCED IMMUNE SYSTEM. IMMUNE CELLS NOT ONLY AFFECT TISSUE HOMEOSTASIS AT THE SITE OF INFLAMMATION BUT ALSO EXERT SYSTEMIC EFFECTS CONTRIBUTING TO MULTIPLE CHRONIC CONDITIONS. RECENT EVIDENCE CLEARLY SUPPORTS AN ALTERED T HELPER 17/REGULATORY T CELL (TH17/TREG) BALANCE LEADING TO THE DEVELOPMENT AND PROGRESSION OF INFLAMMATORY DISEASES THAT NOT ONLY AFFECT THE GASTROINTESTINAL TRACT BUT ALSO HAVE WHOLE-BODY MANIFESTATIONS, INCLUDING INSULIN RESISTANCE. EPIGENETIC MECHANISMS ARE AMENABLE TO BOTH ENVIRONMENTAL AND CIRCULATING FACTORS AND CONTRIBUTE TO DETERMINING THE T CELL LANDSCAPE. THE RECENTLY IDENTIFIED PARTICIPATION OF THE GUT MICROBIOTA IN THE REMODELING OF THE EPIGENOME OF IMMUNE CELLS HAS TRIGGERED A PARADIGM SHIFT IN OUR UNDERSTANDING OF THE ETIOLOGY OF VARIOUS INFLAMMATORY DISEASES AND OPENED NEW PATHS TOWARD THERAPEUTIC STRATEGIES. IN THIS REVIEW, WE PROVIDE AN OVERVIEW OF THE CONTRIBUTION OF THE TH17/TREG BALANCE IN THE DEVELOPMENT AND PROGRESSION OF INFLAMMATORY BOWEL DISEASES AND METABOLIC DISEASES. WE DISCUSS THE INVOLVEMENT OF EPIGENETIC MECHANISMS IN THE REGULATION OF T CELL FUNCTION IN THE PARTICULAR CONTEXT OF DYSBIOSIS. FINALLY, WE EXAMINE THE POTENTIAL FOR NUTRITIONAL INTERVENTIONS AFFECTING THE GUT MICROBIOTA TO RESHAPE THE T CELL EPIGENOME AND ADDRESS THE INFLAMMATORY COMPONENT OF VARIOUS DISEASES. 2017 5 1876 43 EMERGING ROLES FOR EPIGENETIC PROGRAMMING IN THE CONTROL OF INFLAMMATORY SIGNALING INTEGRATION IN HEATH AND DISEASE. MACROPHAGES AND DENDRITIC CELLS INITIATE THE INNATE IMMUNE RESPONSE TO INFECTION AND INJURY AND CONTRIBUTE TO INFLAMMATORY SIGNALING TO MAINTAIN THE HOMEOSTASIS OF VARIOUS TISSUES, WHICH INCLUDES RESIDENT MACROPHAGES FOR THE ELIMINATION OF INVADING MICROORGANISMS AND TISSUE DAMAGE. INAPPROPRIATE INFLAMMATORY SIGNALING CAN LEAD TO PERSISTENT INFLAMMATION AND FURTHER DEVELOP INTO AUTOIMMUNE AND INFLAMMATION-ASSOCIATED DISEASES. INFLAMMATORY SIGNALING PATHWAYS HAVE BEEN WELL CHARACTERIZED, BUT HOW THESE SIGNALING PATHWAYS ARE CONVERTED INTO SUSTAINED AND DIVERSE PATTERNS OF EXPRESSION OF CYTOKINES, CHEMOKINES, AND OTHER GENES IN RESPONSE TO ENVIRONMENTAL CHALLENGES IS UNCLEAR. EMERGING EVIDENCE SUGGESTS THE IMPORTANT ROLE OF EPIGENETIC MECHANISMS IN FINELY TUNING THE OUTCOME OF THE HOST INNATE IMMUNE RESPONSE. AN UNDERSTANDING OF EPIGENETIC REGULATION OF INNATE IMMUNE CELL IDENTITY AND FUNCTION WILL ENABLE THE IDENTIFICATION OF THE MECHANISM BETWEEN GENE-SPECIFIC HOST DEFENSES AND INFLAMMATORY DISEASE AND WILL ALSO ALLOW FOR EXPLORATION OF THE PROGRAM OF INNATE IMMUNE MEMORY IN HEALTH AND DISEASE. THIS INFORMATION COULD BE USED TO DEVELOP THERAPEUTIC AGENTS TO ENHANCE THE HOST RESPONSE, PREVENTING CHRONIC INFLAMMATION THROUGH PRESERVING TISSUES AND SIGNALING INTEGRITY. 2017 6 3661 57 INDUCTION OF INNATE IMMUNE MEMORY BY ENGINEERED NANOPARTICLES IN MONOCYTES/MACROPHAGES: FROM HYPOTHESIS TO REALITY. THE CAPACITY OF ENGINEERED NANOPARTICLES TO ACTIVATE CELLS OF THE INNATE IMMUNE SYSTEM, IN PARTICULAR MONOCYTES AND MACROPHAGES, IS CONSIDERED AT THE BASIS OF THEIR TOXIC/INFLAMMATORY EFFECTS. IT IS, HOWEVER, EVIDENT THAT EVEN NANOPARTICLES THAT DO NOT DIRECTLY INDUCE INFLAMMATORY ACTIVATION, AND ARE THEREFORE CONSIDERED AS SAFE, CAN NEVERTHELESS INDUCE EPIGENETIC MODIFICATIONS AND AFFECT METABOLIC PATHWAYS IN MONOCYTES AND MACROPHAGES. SINCE EPIGENETIC AND METABOLIC CHANGES ARE THE MAIN MECHANISMS OF INNATE MEMORY, WE HAD PREVIOUSLY PROPOSED THAT NANOPARTICLES CAN INDUCE/MODULATE INNATE MEMORY, THAT IS, HAVE THE ABILITY OF SHAPING THE SECONDARY RESPONSE TO INFLAMMATORY CHALLENGES. IN LIGHT OF NEW DATA, IT IS NOW POSSIBLE TO SUPPORT THE ORIGINAL HYPOTHESIS AND SHOW THAT DIFFERENT TYPES OF NANOPARTICLES CAN BOTH DIRECTLY INDUCE INNATE MEMORY, PRIMING MACROPHAGES FOR A MORE POTENT RESPONSE TO SUBSEQUENT STIMULI, AND MODULATE BACTERIA-INDUCED MEMORY BY ATTENUATING THE PRIMING-INDUCED ENHANCEMENT. THIS EVIDENCE RAISES TWO IMPORTANT ISSUES. FIRST, IN ADDITION TO OVERT TOXIC/INFLAMMATORY EFFECTS, WE SHOULD CONSIDER EVALUATING THE CAPACITY TO INDUCE INNATE MEMORY AND THE RELATED EPIGENETIC AND METABOLIC CHANGES IN THE IMMUNOSAFETY ASSESSMENT OF NANOMATERIALS, SINCE MODULATION OF INNATE MEMORY MAY BE AT THE BASIS OF LONG-TERM UNWANTED IMMUNOLOGICAL EFFECTS. THE OTHER IMPORTANT CONSIDERATION IS THAT THIS CAPACITY OF NANOMATERIALS COULD OPEN A NEW AVENUE IN IMMUNOMODULATION AND THE POSSIBILITY OF USING ENGINEERED NANOMATERIALS FOR IMPROVING IMMUNE RESPONSES TO VACCINES AND RESISTANCE TO INFECTIONS, AND MODULATE ANOMALOUS IMMUNE/INFLAMMATORY REACTIONS IN CHRONIC INFLAMMATORY DISEASES, AUTOIMMUNITY, AND A RANGE OF OTHER IMMUNE-RELATED PATHOLOGIES. 2020 7 2289 30 EPIGENETIC REGULATION IN MONOCYTE/MACROPHAGE: A KEY PLAYER DURING ATHEROSCLEROSIS. ATHEROSCLEROSIS IS A CHRONIC INFLAMMATORY DISEASE. RECENTLY, A GROWING BODY OF EVIDENCE EMPHASIZES THAT THE MONOCYTE AND MACROPHAGE DIFFERENTIATION AND ACTIVATION ARE KEY PROCESSES IN THE DEVELOPMENT OF ATHEROSCLEROSIS. HOWEVER, THE REGULATORY MECHANISM THAT MANIPULATES THE FUNCTION OF MONOCYTE AND MACROPHAGE IS STILL UNCLEAR. RECENT YEARS, EPIGENETIC MECHANISMS HAVE RECEIVED A WIDE ATTENTION AND BRING US A NEW FIELD OF VISION. MORE AND MORE EVIDENCE SHOWS THAT EPIGENETICS WEIGHS HEAVILY IN ATHEROSCLEROSIS BY REGULATING THE FUNCTION AND DIFFERENTIATION STATES OF MONOCYTE AND MACROPHAGE. IN THIS REVIEW, WE ILLUMINATE THE EPIGENETIC REGULATION MECHANISMS IN MONOCYTE AND MACROPHAGE AND THEIR CONTRIBUTIONS TO INFLAMMATORY PROCESSES OF ATHEROSCLEROSIS TO PROVIDE NEW THOUGHTS AND FIND NOVEL TARGETS OR BIOMARKERS FOR ATHEROSCLEROSIS. 2017 8 3735 35 INNATE IMMUNE MEMORY: IMPLICATIONS FOR DEVELOPMENT OF PEDIATRIC IMMUNOMODULATORY AGENTS AND ADJUVANTED VACCINES. UNIQUE FEATURES OF IMMUNITY EARLY IN LIFE INCLUDE A DISTINCT IMMUNE SYSTEM PARTICULARLY RELIANT ON INNATE IMMUNITY, WITH WEAK T HELPER (TH)1-POLARIZING IMMUNE RESPONSES, AND IMPAIRED RESPONSES TO CERTAIN VACCINES LEADING TO A HEIGHTENED SUSCEPTIBILITY TO INFECTION. TO THESE IMPORTANT ASPECTS, WE NOW ADD AN INCREASINGLY APPRECIATED CONCEPT THAT THE INNATE IMMUNE SYSTEM DISPLAYS EPIGENETIC MEMORY OF AN EARLIER INFECTION OR VACCINATION, A PHENOMENON THAT HAS BEEN NAMED "TRAINED IMMUNITY." EXPOSURE OF NEONATAL LEUKOCYTES IN VITRO OR NEONATAL ANIMALS OR HUMANS IN VIVO TO SPECIFIC INNATE IMMUNE STIMULI RESULTS IN AN ALTERED INNATE IMMUNE SET POINT. GIVEN THE PARTICULAR IMPORTANCE OF INNATE IMMUNITY EARLY IN LIFE, TRAINED IMMUNITY TO EARLY LIFE INFECTION AND/OR IMMUNIZATION MAY PLAY AN IMPORTANT ROLE IN MODULATING BOTH ACUTE AND CHRONIC DISEASES. 2014 9 6345 49 THE ROLE OF EPIGENETICS IN AUTOIMMUNE/INFLAMMATORY DISEASE. HISTORICALLY, SYSTEMIC SELF-INFLAMMATORY CONDITIONS WERE CLASSIFIED AS EITHER AUTOINFLAMMATORY AND CAUSED BY THE INNATE IMMUNE SYSTEM OR AUTOIMMUNE AND DRIVEN BY ADAPTIVE IMMUNE RESPONSES. HOWEVER, IT BECAME CLEAR THAT REALITY IS MUCH MORE COMPLEX AND THAT AUTOIMMUNE/INFLAMMATORY CONDITIONS RANGE ALONG AN "INFLAMMATORY SPECTRUM" WITH PRIMARILY AUTOINFLAMMATORY VS. AUTOIMMUNE CONDITIONS RESEMBLING EXTREMES AT EITHER END. EPIGENETIC MODIFICATIONS INFLUENCE GENE EXPRESSION AND ALTER CELLULAR FUNCTIONS WITHOUT MODIFYING THE GENOMIC SEQUENCE. METHYLATION OF CPG DNA DINUCLEOTIDES AND/OR THEIR HYDROXYMETHYLATION, POST-TRANSLATIONAL MODIFICATIONS TO AMINO TERMINI OF HISTONE PROTEINS, AND NON-CODING RNA EXPRESSION ARE MAIN EPIGENETIC EVENTS. THE PATHOPHYSIOLOGY OF AUTOIMMUNE/INFLAMMATORY DISEASES HAS BEEN CLOSELY LINKED WITH DISEASE CAUSING GENE MUTATIONS (RARE) OR A COMBINATION OF GENETIC SUSCEPTIBILITY AND EPIGENETIC MODIFICATIONS ARISING FROM EXPOSURE TO THE ENVIRONMENT (MORE COMMON). OVER RECENT YEARS, PROGRESS HAS BEEN MADE IN UNDERSTANDING MOLECULAR MECHANISMS INVOLVED IN SYSTEMIC INFLAMMATION AND THE CONTRIBUTION OF INNATE AND ADAPTIVE IMMUNE RESPONSES. EPIGENETIC EVENTS HAVE BEEN IDENTIFIED AS (I) CENTRAL PATHOPHYSIOLOGICAL FACTORS IN ADDITION TO GENETIC DISEASE PREDISPOSITION AND (II) AS CO-FACTORS DETERMINING CLINICAL PICTURES AND OUTCOMES IN INDIVIDUALS WITH MONOGENIC DISEASE. THUS, A COMPLETE UNDERSTANDING OF EPIGENETIC CONTRIBUTORS TO AUTOIMMUNE/INFLAMMATORY DISEASE WILL RESULT IN APPROACHES TO PREDICT INDIVIDUAL DISEASE OUTCOMES AND THE INTRODUCTION OF EFFECTIVE, TARGET-DIRECTED, AND TOLERABLE THERAPIES. HERE, WE SUMMARIZE RECENT FINDINGS THAT SIGNIFY THE IMPORTANCE OF EPIGENETIC MODIFICATIONS IN AUTOIMMUNE/INFLAMMATORY DISORDERS ALONG THE INFLAMMATORY SPECTRUM CHOOSING THREE EXAMPLES: THE AUTOINFLAMMATORY BONE CONDITION CHRONIC NONBACTERIAL OSTEOMYELITIS (CNO), THE "MIXED PATTERN" DISORDER PSORIASIS, AND THE AUTOIMMUNE DISEASE SYSTEMIC LUPUS ERYTHEMATOSUS (SLE). 2019 10 4488 42 MONOCYTE AND HAEMATOPOIETIC PROGENITOR REPROGRAMMING AS COMMON MECHANISM UNDERLYING CHRONIC INFLAMMATORY AND CARDIOVASCULAR DISEASES. A LARGE NUMBER OF CARDIOVASCULAR EVENTS ARE NOT PREVENTED BY CURRENT THERAPEUTIC REGIMENS. IN SEARCH FOR ADDITIONAL, INNOVATIVE STRATEGIES, IMMUNE CELLS HAVE BEEN RECOGNIZED AS KEY PLAYERS CONTRIBUTING TO ATHEROSCLEROTIC PLAQUE PROGRESSION AND DESTABILIZATION. PARTICULARLY THE ROLE OF INNATE IMMUNE CELLS IS OF MAJOR INTEREST, FOLLOWING THE RECENT PARADIGM SHIFT THAT INNATE IMMUNITY, LONG CONSIDERED TO BE INCAPABLE OF LEARNING, DOES EXHIBIT IMMUNOLOGICAL MEMORY MEDIATED VIA EPIGENETIC REPROGRAMMING. COMPELLING EVIDENCE SHOWS THAT ATHEROSCLEROTIC RISK FACTORS PROMOTE IMMUNE CELL MIGRATION BY PRE-ACTIVATION OF CIRCULATING INNATE IMMUNE CELLS. INNATE IMMUNE CELL ACTIVATION VIA METABOLIC AND EPIGENETIC REPROGRAMMING PERPETUATES A SYSTEMIC LOW-GRADE INFLAMMATORY STATE IN CARDIOVASCULAR DISEASE (CVD) THAT IS ALSO COMMON IN OTHER CHRONIC INFLAMMATORY DISORDERS. THIS OPENS A NEW THERAPEUTIC AREA IN WHICH METABOLIC OR EPIGENETIC MODULATION OF INNATE IMMUNE CELLS MAY RESULT IN DECREASED SYSTEMIC CHRONIC INFLAMMATION, ALLEVIATING CVD, AND ITS CO-MORBIDITIES. 2018 11 6504 56 TRAINED INNATE IMMUNITY AND ITS IMPLICATIONS FOR MUCOSAL IMMUNITY AND INFLAMMATION. THE LONG-STANDING DOGMA THAT IMMUNOLOGICAL MEMORY IS THE EXCLUSIVE PREROGATIVE OF THE ADAPTIVE IMMUNE SYSTEM HAS BEEN CHALLENGED BY EMERGING EVIDENCE THAT INNATE IMMUNITY CAN ALSO MAINTAIN MEMORY OF PAST EVENTS. SUCH IMMUNOLOGICAL IMPRINTING TAKES TWO FORMS, TRAINED INNATE IMMUNITY AND TOLERANCE. TRAINED IMMUNITY INVOLVES METABOLIC AND EPIGENETIC ADAPTATIONS IN INNATE IMMUNE CELLS AND THEIR PROGENITORS IN THE BONE MARROW UPON EXPOSURE TO CERTAIN MICROBIAL AND/OR INFLAMMATORY STIMULI SO THAT THE "TRAINED" CELLS WOULD BE POISED TO RESPOND MUCH FASTER AND STRONGER TO A SUBSEQUENT CHALLENGE (E.G., A NEW INFECTION THAT IS NOT NECESSARILY THE SAME AS THE EARLIER ONE). CONVERSELY, TOLERANCE LEADS TO ATTENUATED IMMUNE RESPONSES TO SECONDARY STIMULI. THIS REVIEW FOCUSES ON TRAINED IMMUNITY AND DISCUSSES EVIDENCE FOR ITS EXISTENCE FROM LOWER ORGANISMS TO HUMANS, ITS MECHANISTIC UNDERPINNINGS, AND ITS TRANSLATIONAL RAMIFICATIONS. ALTHOUGH TRAINED IMMUNITY CAN BE CONSIDERED AS AN EVOLUTIONARILY CONSERVED BENEFICIAL RESPONSE AGAINST REINFECTIONS, IN THE SETTING OF MODERN SOCIETIES WITH HIGH PREVALENCE OF CHRONIC MUCOSAL AND SYSTEMIC INFLAMMATORY DISEASES, TRAINED IMMUNITY COULD ALSO PROMOTE MALADAPTIVE IMMUNE RESPONSES THAT AGGRAVATE PATHOLOGY. THUS, DEPENDING ON CONTEXT, INNATE IMMUNE MEMORY COULD BE THERAPEUTICALLY MANIPULATED USING DEFINED AGONISTS TO EITHER PROMOTE INNATE IMMUNE RESPONSES (PARTICULARLY USEFUL FOR THE TREATMENT OF INFECTIONS OR CHEMOTHERAPY-INDUCED MYELOSUPPRESSION) OR SUPPRESS EXCESSIVE INFLAMMATION IN INFLAMMATORY AND AUTOIMMUNE DISEASES. 2019 12 3539 30 IMMUNE SENESCENCE, EPIGENETICS AND AUTOIMMUNITY. AGING OF THE IMMUNE SYSTEM IN HUMANS AND ANIMALS IS CHARACTERIZED BY A DECLINE IN BOTH ADAPTIVE AND INNATE IMMUNE RESPONSES. PARADOXICALLY, AGING IS ALSO ASSOCIATED WITH A STATE OF CHRONIC INFLAMMATION ("INFLAMMAGING") AND AN INCREASED LIKELIHOOD OF DEVELOPING AUTOIMMUNE DISEASES. EPIGENETIC CHANGES IN NON-DIVIDING AND DIVIDING CELLS, INCLUDING IMMUNE CELLS, DUE TO ENVIRONMENTAL FACTORS CONTRIBUTE TO THE INFLAMMATION AND AUTOIMMUNITY THAT CHARACTERIZE BOTH THE STATE AND DISEASES OF AGING. HERE, WE REVIEW THE EPIGENETIC MECHANISMS INVOLVED IN THE DEVELOPMENT OF IMMUNE SENESCENCE AND AUTOIMMUNITY IN OLD AGE. 2018 13 5059 41 PHENOTYPIC AND IMMUNOMETABOLIC ASPECTS ON STEM CELL MEMORY AND RESIDENT MEMORY CD8(+) T CELLS. THE IMMUNE SYSTEM, SMARTLY AND SURPRISINGLY, SAVES THE EXPOSURE OF A PARTICULAR PATHOGEN IN ITS MEMORY AND REACTS TO THE PATHOGEN VERY RAPIDLY, PREVENTING SERIOUS DISEASES. IMMUNOLOGISTS HAVE LONG BEEN FASCINATED BY UNDERSTANDING THE ABILITY TO RECALL AND RESPOND FASTER AND MORE VIGOROUSLY TO A PATHOGEN, KNOWN AS "MEMORY". T-CELL POPULATIONS CAN BE BETTER DESCRIBED BY USING MORE SOPHISTICATED TECHNIQUES TO DEFINE PHENOTYPE, TRANSCRIPTIONAL AND EPIGENETIC SIGNATURES AND METABOLIC PATHWAYS (SINGLE-CELL RESOLUTION), WHICH UNCOVERED THE HETEROGENEITY OF THE MEMORY T-COMPARTMENT. PHENOTYPE, EFFECTOR FUNCTIONS, MAINTENANCE, AND METABOLIC PATHWAYS HELP IDENTIFY THESE DIFFERENT SUBSETS. HERE, WE EXAMINE RECENT DEVELOPMENTS IN THE CHARACTERIZATION OF THE HETEROGENEITY OF THE MEMORY T CELL COMPARTMENT. IN PARTICULAR, WE FOCUS ON THE EMERGING ROLE OF CD8(+) T(RM) AND T(SCM) CELLS, PROVIDING EVIDENCE ON HOW THEIR IMMUNOMETABOLISM OR MODULATION CAN PLAY A VITAL ROLE IN THEIR GENERATION AND MAINTENANCE IN CHRONIC CONDITIONS SUCH AS INFECTIONS OR AUTOIMMUNE DISEASES. 2022 14 6136 44 THE EPIGENETICS OF MULTIPLE SCLEROSIS AND OTHER RELATED DISORDERS. MULTIPLE SCLEROSIS (MS) IS A DEMYELINATING DISEASE CHARACTERIZED BY CHRONIC INFLAMMATION OF THE CENTRAL NERVOUS SYSTEM (CNS) GRAY AND WHITE MATTER. ALTHOUGH THE CAUSE OF MS IS UNKNOWN, IT IS WIDELY APPRECIATED THAT INNATE AND ADAPTIVE IMMUNE PROCESSES CONTRIBUTE TO ITS PATHOGENESIS. THESE INCLUDE MICROGLIA/MACROPHAGE ACTIVATION, PRO-INFLAMMATORY T-CELL (TH1) RESPONSES AND HUMORAL RESPONSES. ADDITIONALLY, THERE IS EVIDENCE INDICATING THAT MS HAS A NEURODEGENERATIVE COMPONENT SINCE NEURONAL AND AXONAL LOSS OCCURS EVEN IN THE ABSENCE OF OVERT INFLAMMATION. THESE ASPECTS ALSO FORM THE RATIONALE FOR CLINICAL MANAGEMENT OF THE DISEASE. HOWEVER, THE CURRENTLY AVAILABLE THERAPIES TO CONTROL THE DISEASE ARE ONLY PARTIALLY EFFECTIVE AT BEST INDICATING THAT MORE EFFECTIVE THERAPEUTIC SOLUTIONS ARE URGENTLY NEEDED. IT IS APPRECIATED THAT IN THE IMMUNE-DRIVEN AND NEURODEGENERATIVE PROCESSES MS-SPECIFIC DEREGULATION OF GENE EXPRESSIONS AND RESULTING PROTEIN DYSFUNCTION ARE THOUGHT TO PLAY A CENTRAL ROLE. THESE DEVIATIONS IN GENE EXPRESSION PATTERNS CONTRIBUTE TO THE INFLAMMATORY RESPONSE IN THE CNS, AND TO NEURONAL OR AXONAL LOSS. EPIGENETIC MECHANISMS CONTROL TRANSCRIPTION OF MOST, IF NOT ALL GENES, IN NUCLEATED CELLS INCLUDING CELLS OF THE CNS AND IN HAEMATOPOIETIC CELLS. MS-SPECIFIC ALTERATIONS IN EPIGENETIC REGULATION OF GENE EXPRESSION MAY THEREFORE LIE AT THE HEART OF THE DEREGULATION OF GENE EXPRESSION IN MS. AS SUCH, EPIGENETIC MECHANISMS MOST LIKELY PLAY AN IMPORTANT ROLE IN DISEASE PATHOGENESIS. IN THIS REVIEW WE DISCUSS A ROLE FOR MS-SPECIFIC DEREGULATION OF EPIGENETIC FEATURES THAT CONTROL GENE EXPRESSION IN THE CNS AND IN THE PERIPHERY. FURTHERMORE, WE DISCUSS THE APPLICATION OF SMALL MOLECULE INHIBITORS THAT TARGET THE EPIGENETIC MACHINERY TO AMELIORATE DISEASE IN EXPERIMENTAL ANIMAL MODELS, INDICATING THAT SUCH APPROACHES MAY BE APPLICABLE TO MS PATIENTS. 2014 15 2923 27 GENE-SPECIFIC EPIGENETIC REGULATION IN SERIOUS INFECTIONS WITH SYSTEMIC INFLAMMATION. INFLAMMATION IS A FUNDAMENTAL BIOLOGIC PROCESS THAT IS EVOLUTIONALLY CONSERVED BY A GERM LINE CODE. THE INTERPLAY BETWEEN EPIGENETICS AND ENVIRONMENT DIRECTS THE CODE INTO TEMPORALLY DISTINCT INFLAMMATORY RESPONSES, WHICH CAN BE ACUTE OR CHRONIC. HERE, WE DISCUSS THE EPIGENETIC PROCESSES OF INNATE IMMUNE CELLS DURING SERIOUS INFECTIONS WITH SYSTEMIC INFLAMMATION IN FOUR STAGES: HOMEOSTASIS, INCITEMENT, EVOLUTION, AND RESOLUTION. WE DESCRIBE FEED-FORWARD LOOPS OF SERIOUS INFECTIONS WITH SYSTEMIC INFLAMMATION THAT CREATE GENE-SPECIFIC SILENT FACULTATIVE HETEROCHROMATIN AND ACTIVE EUCHROMATIN ACCORDING TO GENE FUNCTION, AND SPECULATE ON THE ROLE OF EPIGENETICS IN SURVIVAL. 2010 16 2861 66 FROM TRAINED IMMUNITY IN ALLERGY TO TRAINED IMMUNITY-BASED ALLERGEN VACCINES. INNATE IMMUNE CELLS EXPERIENCE LONG LASTING METABOLIC AND EPIGENETIC CHANGES AFTER AN ENCOUNTER WITH SPECIFIC STIMULI. THIS FACILITATES ENHANCED IMMUNE RESPONSES UPON SECONDARY EXPOSITION TO BOTH THE SAME AND UNRELATED PATHOGENS, A PROCESS TERMED TRAINED IMMUNITY. TRAINED IMMUNITY-BASED VACCINES (TIBV) ARE VACCINES ABLE TO INDUCE INNATE IMMUNE MEMORY, THUS CONFERRING HETEROLOGOUS PROTECTION AGAINST A BROAD RANGE OF PATHOGENS. WHILE TRAINED IMMUNITY HAS BEEN WELL DOCUMENTED IN THE CONTEXT OF INFECTIONS AND MULTIPLE IMMUNE-MEDIATED DISEASES, THE ROLE OF INNATE IMMUNE MEMORY AND ITS CONTRIBUTION TO THE INITIATION AND MAINTENANCE OF CHRONIC ALLERGIC DISEASES REMAINS POORLY UNDERSTOOD. OVER THE LAST YEARS, DIFFERENT STUDIES ATTEMPTING TO UNCOVER THE ROLE OF TRAINED IMMUNITY IN ALLERGY HAVE EMERGED. EXPOSITION TO ENVIRONMENTAL FACTORS IMPACTING ALLERGY DEVELOPMENT SUCH AS ALLERGENS OR VIRUSES INDUCES THE REPROGRAMMING OF INNATE IMMUNE CELLS TO ACQUIRE A MORE PRO-INFLAMMATORY PHENOTYPE IN THE CONTEXT OF ASTHMA OR FOOD ALLERGY. SEVERAL STUDIES HAVE CONVINCINGLY DEMONSTRATED THAT PREVENTION OF VIRAL INFECTIONS USING TIBV CONTRIBUTES TO REDUCE WHEEZING ATTACKS IN CHILDREN, WHICH REPRESENT A HIGH-RISK FACTOR FOR ASTHMA DEVELOPMENT LATER IN LIFE. INNATE IMMUNE CELLS TRAINED WITH SPECIFIC STIMULI MIGHT ALSO ACQUIRE ANTI-INFLAMMATORY FEATURES AND PROMOTE TOLERANCE, WHICH MAY HAVE IMPORTANT IMPLICATIONS FOR CHRONIC INFLAMMATORY DISEASES SUCH AS ALLERGIES. RECENT FINDINGS SHOWED THAT ALLERGOID-MANNAN CONJUGATES, WHICH ARE NEXT GENERATION VACCINES FOR ALLERGEN-SPECIFIC IMMUNOTHERAPY (AIT), ARE ABLE TO REPROGRAM MONOCYTES INTO TOLEROGENIC DENDRITIC CELLS BY MECHANISMS DEPENDING ON METABOLIC AND EPIGENETIC REWIRING. A BETTER UNDERSTANDING OF THE UNDERLYING MECHANISMS OF TRAINED IMMUNITY IN ALLERGY WILL PAVE THE WAY FOR THE DESIGN OF NOVEL TRAINED IMMUNITY-BASED ALLERGEN VACCINES AS POTENTIAL ALTERNATIVE STRATEGIES FOR THE PREVENTION AND TREATMENT OF ALLERGIC DISEASES. 2023 17 6200 39 THE INFLAMMATORY EFFECT OF EPIGENETIC FACTORS AND MODIFICATIONS IN TYPE 2 DIABETES. INFLAMMATION HAS A CENTRAL ROLE IN THE ETIOLOGY OF TYPE 2 DIABETES (T2D) AND ITS COMPLICATIONS. BOTH GENETIC AND EPIGENETIC FACTORS HAVE BEEN IMPLICATED IN THE DEVELOPMENT OF T2D-ASSOCIATED INFLAMMATION. EPIGENETIC MECHANISMS REGULATE THE FUNCTION OF SEVERAL COMPONENTS OF THE IMMUNE SYSTEM. DIABETIC CONDITIONS TRIGGER ABERRANT EPIGENETIC ALTERATIONS THAT CONTRIBUTE TO THE PROGRESSION OF INSULIN RESISTANCE AND BETA-CELL DYSFUNCTION BY INDUCTION OF INFLAMMATORY RESPONSES. THUS, TARGETING EPIGENETIC FACTORS AND MODIFICATIONS, AS ONE OF THE UNDERLYING CAUSES OF INFLAMMATION, COULD LEAD TO THE DEVELOPMENT OF NOVEL IMMUNE-BASED STRATEGIES FOR THE TREATMENT OF T2D. THE AIM OF THIS REVIEW IS TO PROVIDE AN OVERVIEW OF THE EPIGENETIC MECHANISMS INVOLVED IN THE PROPAGATION AND PERPETUATION OF CHRONIC INFLAMMATION IN T2D. WE ALSO DISCUSS THE POSSIBLE ANTI-INFLAMMATORY APPROACHES THAT TARGET EPIGENETIC FACTORS FOR THE TREATMENT OF T2D. 2020 18 5932 42 TARGETING EPIGENETIC REGULATORS FOR INFLAMMATION: MECHANISMS AND INTERVENTION THERAPY. EMERGING EVIDENCE INDICATES THAT RESOLUTION OF INFLAMMATION IS A CRITICAL AND DYNAMIC ENDOGENOUS PROCESS FOR HOST TISSUES DEFENDING AGAINST EXTERNAL INVASIVE PATHOGENS OR INTERNAL TISSUE INJURY. IT HAS LONG BEEN KNOWN THAT AUTOIMMUNE DISEASES AND CHRONIC INFLAMMATORY DISORDERS ARE CHARACTERIZED BY DYSREGULATED IMMUNE RESPONSES, LEADING TO EXCESSIVE AND UNCONTROL TISSUE INFLAMMATION. THE DYSREGULATION OF EPIGENETIC ALTERATIONS INCLUDING DNA METHYLATION, POSTTRANSLATIONAL MODIFICATIONS TO HISTONE PROTEINS, AND NONCODING RNA EXPRESSION HAS BEEN IMPLICATED IN A HOST OF INFLAMMATORY DISORDERS AND THE IMMUNE SYSTEM. THE INFLAMMATORY RESPONSE IS CONSIDERED AS A CRITICAL TRIGGER OF EPIGENETIC ALTERATIONS THAT IN TURN INTERCEDE INFLAMMATORY ACTIONS. THUS, UNDERSTANDING THE MOLECULAR MECHANISM THAT DICTATES THE OUTCOME OF TARGETING EPIGENETIC REGULATORS FOR INFLAMMATORY DISEASE IS REQUIRED FOR INFLAMMATION RESOLUTION. IN THIS ARTICLE, WE ELUCIDATE THE CRITICAL ROLE OF THE NUCLEAR FACTOR-KAPPAB SIGNALING PATHWAY, JAK/STAT SIGNALING PATHWAY, AND THE NLRP3 INFLAMMASOME IN CHRONIC INFLAMMATORY DISEASES. AND WE FORMULATE THE RELATIONSHIP BETWEEN INFLAMMATION, CORONAVIRUS DISEASE 2019, AND HUMAN CANCERS. ADDITIONALLY, WE REVIEW THE MECHANISM OF EPIGENETIC MODIFICATIONS INVOLVED IN INFLAMMATION AND INNATE IMMUNE CELLS. ALL THAT MATTERS IS THAT WE PROPOSE AND DISCUSS THE REJUVENATION POTENTIAL OF INTERVENTIONS THAT TARGET EPIGENETIC REGULATORS AND REGULATORY MECHANISMS FOR CHRONIC INFLAMMATION-ASSOCIATED DISEASES TO IMPROVE THERAPEUTIC OUTCOMES. 2022 19 5359 40 REBOOTING REGULATORY T CELL AND DENDRITIC CELL FUNCTION IN IMMUNE-MEDIATED INFLAMMATORY DISEASES: BIOMARKER AND THERAPY DISCOVERY UNDER A MULTI-OMICS LENS. IMMUNE-MEDIATED INFLAMMATORY DISEASES (IMIDS) ARE A GROUP OF AUTOIMMUNE AND CHRONIC INFLAMMATORY DISORDERS WITH CONSTANTLY INCREASING PREVALENCE IN THE MODERN WORLD. THE VAST MAJORITY OF IMIDS DEVELOP AS A CONSEQUENCE OF COMPLEX MECHANISMS DEPENDENT ON GENETIC, EPIGENETIC, MOLECULAR, CELLULAR, AND ENVIRONMENTAL ELEMENTS, THAT LEAD TO DEFECTS IN IMMUNE REGULATORY GUARDIANS OF TOLERANCE, SUCH AS DENDRITIC (DCS) AND REGULATORY T (TREGS) CELLS. AS A RESULT OF THIS DYSFUNCTION, IMMUNE TOLERANCE COLLAPSES AND PATHOGENESIS EMERGES. DEEPER UNDERSTANDING OF SUCH DISEASE DRIVING MECHANISMS REMAINS A MAJOR CHALLENGE FOR THE PREVENTION OF INFLAMMATORY DISORDERS. THE RECENT RENAISSANCE IN HIGH THROUGHPUT TECHNOLOGIES HAS ENABLED THE INCREASE IN THE AMOUNT OF DATA COLLECTED THROUGH MULTIPLE OMICS LAYERS, WHILE ADDITIONALLY NARROWING THE RESOLUTION DOWN TO THE SINGLE CELL LEVEL. IN LIGHT OF THE AFOREMENTIONED, THIS REVIEW FOCUSES ON DCS AND TREGS AND DISCUSSES HOW MULTI-OMICS APPROACHES CAN BE HARNESSED TO CREATE ROBUST CELL-BASED IMID BIOMARKERS IN HOPE OF LEADING TO MORE EFFICIENT AND PATIENT-TAILORED THERAPEUTIC INTERVENTIONS. 2022 20 2070 41 EPIGENETIC CONTROL OF SKIN IMMUNITY. EPIGENETICS HAS BEEN WELL UNDERSTOOD FOR ITS ROLE IN CELL DEVELOPMENT; HOWEVER, IT IS NOW KNOWN TO REGULATE MANY PROCESSES INVOLVED IN IMMUNE CELL ACTIVATION IN A VARIETY OF CELLS. THE SKIN MAINTAINS HOMEOSTASIS VIA CROSSTALK BETWEEN IMMUNE AND NON-IMMUNE CELLS. DISRUPTION OF NORMAL EPIGENETIC REGULATION IN THESE CELLS MAY ALTER THE TRANSCRIPTION OF IMMUNE-REGULATORY FACTORS AND AFFECT THE IMMUNOLOGICAL BALANCE IN THE SKIN. THIS REVIEW SUMMARIZES RECENT EVIDENCE FOR THE EPIGENETIC REGULATION OF SKIN IMMUNITY. MUCH OF WHAT IS KNOWN ABOUT EPIGENETIC INVOLVEMENT IN SKIN IMMUNITY IS ASSOCIATED WITH DNA METHYLATION. THIS REVIEW FOCUSES ON EPIGENETIC REGULATION OF HISTONE MODIFICATION AND CHROMATIN REMODELING AND DESCRIBES THEIR ROLE IN THE TRANSCRIPTIONAL REGULATION OF IMMUNE-REGULATORY FACTORS. WHILE MUCH IS STILL UNKNOWN REGARDING THE REGULATION OF SKIN IMMUNITY VIA HISTONE MODIFICATION OR CHROMATIN REMODELING, THESE PROCESSES MAY UNDERLIE THE PATHOGENESIS OF CHRONIC CUTANEOUS IMMUNE DISORDERS. 2023