1 4489 90 MONOCYTE AND MACROPHAGE IMMUNOMETABOLISM IN ATHEROSCLEROSIS. ATHEROSCLEROSIS IS CHARACTERIZED BY CHRONIC LOW GRADE INFLAMMATION OF ARTERIES THAT RESULTS IN THE DEVELOPMENT OF LIPID DENSE PLAQUES. CHRONIC INFLAMMATION INDUCED BY WESTERN-TYPE DIET IS ASSOCIATED WITH THE RISK OF DEVELOPING ATHEROSCLEROSIS, AND NEW INSIGHTS SHED LIGHT ON THE IMPORTANCE OF METABOLIC AND FUNCTIONAL REPROGRAMMING IN MONOCYTES AND MACROPHAGES FOR PROGRESSION OF ATHEROSCLEROSIS. THIS REVIEW AIMS TO PROVIDE AN OVERVIEW OF OUR CURRENT UNDERSTANDING INTO HOW THE METABOLIC REPROGRAMMING OF GLUCOSE, CHOLESTEROL, FATTY ACID, AND AMINO ACID METABOLISM IN MACROPHAGES CONTRIBUTES TO INFLAMMATION DURING ATHEROSCLEROSIS. RECENT INSIGHTS SUGGEST THAT TRANSCRIPTIONAL AND EPIGENETIC ADAPTATION WITHIN INNATE IMMUNE CELLS (TERMED TRAINED IMMUNITY) PLAY AN IMPORTANT ROLE IN THE PATHOGENESIS OF ATHEROSCLEROSIS. WE PROPOSE THAT METABOLIC CHANGES INDUCED BY PRO-ATHEROGENIC LIPOPROTEINS PARTLY MEDIATE THESE CHANGES IN TRAINED MACROPHAGES. FINALLY, WE DISCUSS THE POSSIBILITY OF MANIPULATING CELLULAR METABOLISM OF IMMUNE CELLS FOR TARGETED THERAPEUTIC INTERVENTION AGAINST ATHEROSCLEROSIS. 2018 2 3734 44 INNATE IMMUNE MEMORY IN MONOCYTES AND MACROPHAGES: THE POTENTIAL THERAPEUTIC STRATEGIES FOR ATHEROSCLEROSIS. ATHEROSCLEROSIS IS A COMPLEX METABOLIC DISEASE CHARACTERIZED BY THE DYSFUNCTION OF LIPID METABOLISM AND CHRONIC INFLAMMATION IN THE INTIMAL SPACE OF THE VESSEL. AS THE MOST ABUNDANT INNATE IMMUNE CELLS, MONOCYTE-DERIVED MACROPHAGES PLAY A PIVOTAL ROLE IN THE INFLAMMATORY RESPONSE, CHOLESTEROL METABOLISM, AND FOAM CELL FORMATION. IN RECENT DECADES, IT HAS BEEN DEMONSTRATED THAT MONOCYTES AND MACROPHAGES CAN ESTABLISH INNATE IMMUNE MEMORY (ALSO TERMED TRAINED IMMUNITY) VIA ENDOGENOUS AND EXOGENOUS ATHEROGENIC STIMULI AND EXHIBIT A LONG-LASTING PROINFLAMMATORY PHENOTYPE. THE IMPORTANT CELLULAR METABOLISM PROCESSES, INCLUDING GLYCOLYSIS, OXIDATIVE PHOSPHORYLATION (OXPHOS), THE TRICARBOXYLIC ACID (TCA) CYCLE, FATTY ACID SYNTHESIS, AND CHOLESTEROL SYNTHESIS, ARE REPROGRAMMED. TRAINED MONOCYTES/MACROPHAGES WITH INNATE IMMUNE MEMORY CAN BE PERSISTENTLY HYPERACTIVATED AND CAN UNDERGO EXTENSIVE EPIGENETIC REWIRING, WHICH CONTRIBUTES TO THE PATHOPHYSIOLOGICAL DEVELOPMENT OF ATHEROSCLEROSIS VIA INCREASED PROINFLAMMATORY CYTOKINE PRODUCTION AND LIPID ACCUMULATION. HERE, WE PROVIDE AN OVERVIEW OF THE REGULATION OF CELLULAR METABOLIC PROCESSES AND EPIGENETIC MODIFICATIONS OF INNATE IMMUNE MEMORY IN MONOCYTES/MACROPHAGES AS WELL AS THE POTENTIAL ENDOGENOUS AND EXOGENOUS STIMULATIONS INVOLVED IN THE PROGRESSION OF ATHEROSCLEROSIS THAT HAVE BEEN REPORTED RECENTLY. THESE ELUCIDATIONS MIGHT BE BENEFICIAL FOR FURTHER UNDERSTANDING INNATE IMMUNE MEMORY AND THE DEVELOPMENT OF THERAPEUTIC STRATEGIES FOR INFLAMMATORY DISEASES AND ATHEROSCLEROSIS. 2022 3 6505 32 TRAINED INNATE IMMUNITY AS A NOVEL MECHANISM LINKING INFECTION AND THE DEVELOPMENT OF ATHEROSCLEROSIS. RATIONALE: THERE IS STRONG EPIDEMIOLOGICAL EVIDENCE FOR AN ASSOCIATION BETWEEN ACUTE AND CHRONIC INFECTIONS AND THE OCCURRENCE OF ATHEROSCLEROTIC CARDIOVASCULAR DISEASE. THE UNDERLYING PATHOPHYSIOLOGICAL MECHANISMS REMAIN UNCLEAR. MONOCYTE-DERIVED MACROPHAGES ARE THE MOST ABUNDANT IMMUNE CELLS IN ATHEROSCLEROTIC PLAQUES. IT HAS RECENTLY BEEN ESTABLISHED THAT MONOCYTES/MACROPHAGES CAN DEVELOP A LONG-LASTING PROINFLAMMATORY PHENOTYPE AFTER BRIEF STIMULATION WITH MICRO-ORGANISMS OR MICROBIAL PRODUCTS, WHICH HAS BEEN TERMED TRAINED IMMUNITY. OBJECTIVE: THE AIM OF THIS STUDY IS TO ASSESS WHETHER TRAINED IMMUNITY MEDIATES THE LINK BETWEEN INFECTIONS AND ATHEROSCLEROTIC CARDIOVASCULAR DISEASE. METHODS AND RESULTS: BRIEF EXPOSURE OF MONOCYTES TO VARIOUS MICRO-ORGANISMS RESULTS IN THE DEVELOPMENT OF MACROPHAGES WITH A PERSISTENT PROINFLAMMATORY PHENOTYPE: THIS REPRESENTS A DE FACTO NONSPECIFIC INNATE IMMUNE MEMORY, WHICH HAS BEEN TERMED TRAINED IMMUNITY. THIS IS MEDIATED BY EPIGENETIC REPROGRAMMING AT THE LEVEL OF HISTONE METHYLATION AND A PROFOUND REWIRING OF INTRACELLULAR METABOLISM. ALTHOUGH THIS MECHANISM OFFERS POWERFUL PROTECTION AGAINST REINFECTION, TRAINED MACROPHAGES DISPLAY AN ATHEROGENIC PHENOTYPE IN TERMS OF CYTOKINE PRODUCTION AND FOAM CELL FORMATION. TRAINED MONOCYTES ARE PRESENT UP TO 3 MONTHS AFTER EXPERIMENTAL INFECTION IN HUMANS. MOREOVER, A TRAINED IMMUNITY PHENOTYPE IS PRESENT IN PATIENTS WITH ESTABLISHED ATHEROSCLEROSIS. CONCLUSIONS: WE PROPOSE THAT TRAINED IMMUNITY PROVIDES THE MISSING MECHANISTIC LINK THAT EXPLAINS THE ASSOCIATION BETWEEN INFECTIONS AND ATHEROSCLEROSIS. THEREFORE, PHARMACOLOGICAL MODULATION OF TRAINED IMMUNITY HAS THE POTENTIAL TO PREVENT INFECTION-RELATED ATHEROSCLEROTIC CARDIOVASCULAR DISEASE IN THE FUTURE. 2018 4 6498 30 TRAINED IMMUNITY IN MONOCYTE/MACROPHAGE: NOVEL MECHANISM OF PHYTOCHEMICALS IN THE TREATMENT OF ATHEROSCLEROTIC CARDIOVASCULAR DISEASE. ATHEROSCLEROSIS (AS) IS THE PATHOLOGY OF ATHEROSCLEROTIC CARDIOVASCULAR DISEASES (ASCVD), CHARACTERIZED BY PERSISTENT CHRONIC INFLAMMATION IN THE VESSEL WALL, IN WHICH MONOCYTES/MACROPHAGES PLAY A KEY ROLE. IT HAS BEEN REPORTED THAT INNATE IMMUNE SYSTEM CELLS CAN ASSUME A PERSISTENT PROINFLAMMATORY STATE AFTER SHORT STIMULATION WITH ENDOGENOUS ATHEROGENIC STIMULI. THE PATHOGENESIS OF AS CAN BE INFLUENCED BY THIS PERSISTENT HYPERACTIVATION OF THE INNATE IMMUNE SYSTEM, WHICH IS TERMED TRAINED IMMUNITY. TRAINED IMMUNITY HAS ALSO BEEN IMPLICATED AS A KEY PATHOLOGICAL MECHANISM, LEADING TO PERSISTENT CHRONIC INFLAMMATION IN AS. TRAINED IMMUNITY IS MEDIATED VIA EPIGENETIC AND METABOLIC REPROGRAMMING AND OCCURS IN MATURE INNATE IMMUNE CELLS AND THEIR BONE MARROW PROGENITORS. NATURAL PRODUCTS ARE PROMISING CANDIDATES FOR NOVEL PHARMACOLOGICAL AGENTS THAT CAN BE USED TO PREVENT OR TREAT CARDIOVASCULAR DISEASES (CVD). A VARIETY OF NATURAL PRODUCTS AND AGENTS EXHIBITING ANTIATHEROSCLEROTIC ABILITIES HAVE BEEN REPORTED TO POTENTIALLY INTERFERE WITH THE PHARMACOLOGICAL TARGETS OF TRAINED IMMUNITY. THIS REVIEW DESCRIBES IN AS MUCH DETAIL AS POSSIBLE THE MECHANISMS INVOLVED IN TRAINED IMMUNITY AND HOW PHYTOCHEMICALS OF THIS PROCESS INHIBIT AS BY AFFECTING TRAINED MONOCYTES/MACROPHAGES. 2023 5 6497 35 TRAINED IMMUNITY IN ATHEROSCLEROTIC CARDIOVASCULAR DISEASE. TRAINED IMMUNITY, ALSO KNOWN AS INNATE IMMUNE MEMORY, IS A PERSISTENT HYPER-RESPONSIVE FUNCTIONAL STATE OF INNATE IMMUNE CELLS. ACCUMULATING EVIDENCE IMPLICATES TRAINED IMMUNITY AS AN UNDERLYING MECHANISM OF CHRONIC INFLAMMATION IN ATHEROSCLEROTIC CARDIOVASCULAR DISEASE. IN THIS CONTEXT, TRAINED IMMUNITY IS INDUCED BY ENDOGENOUS ATHEROSCLEROSIS-PROMOTING FACTORS, SUCH AS MODIFIED LIPOPROTEINS OR HYPERGLYCAEMIA, CAUSING BROAD METABOLIC AND EPIGENETIC REPROGRAMMING OF THE MYELOID CELL COMPARTMENT. IN ADDITION TO TRADITIONAL CARDIOVASCULAR RISK FACTORS, LIFESTYLE FACTORS, INCLUDING UNHEALTHY DIETS, SEDENTARY LIFESTYLE, SLEEP DEPRIVATION AND PSYCHOSOCIAL STRESS, AS WELL AS INFLAMMATORY COMORBIDITIES, HAVE BEEN SHOWN TO ACTIVATE TRAINED IMMUNITY-LIKE MECHANISMS IN BONE MARROW HAEMATOPOIETIC STEM CELLS. IN THIS REVIEW, WE DISCUSS THE MOLECULAR AND CELLULAR MECHANISMS OF TRAINED IMMUNITY, ITS SYSTEMIC REGULATION THROUGH HAEMATOPOIETIC PROGENITOR CELLS IN THE BONE MARROW, AND THE ACTIVATION OF THESE MECHANISMS BY CARDIOVASCULAR DISEASE RISK FACTORS. WE ALSO HIGHLIGHT OTHER TRAINED IMMUNITY FEATURES THAT ARE RELEVANT FOR ATHEROSCLEROTIC CARDIOVASCULAR DISEASE, INCLUDING THE DIVERSE CELL TYPES THAT SHOW MEMORY CHARACTERISTICS AND TRANSGENERATIONAL INHERITANCE OF TRAINED IMMUNITY TRAITS. FINALLY, WE PROPOSE POTENTIAL STRATEGIES FOR THE THERAPEUTIC MODULATION OF TRAINED IMMUNITY TO MANAGE ATHEROSCLEROTIC CARDIOVASCULAR DISEASE. 2023 6 4488 29 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 7 2168 23 EPIGENETIC MECHANISMS IN MONOCYTES/MACROPHAGES REGULATE INFLAMMATION IN CARDIOMETABOLIC AND VASCULAR DISEASE. CARDIOMETABOLIC AND VASCULAR DISEASE, WITH THEIR ASSOCIATED SECONDARY COMPLICATIONS, ARE THE LEADING CAUSE OF MORBIDITY AND MORTALITY IN WESTERN SOCIETY. CHRONIC INFLAMMATION IS A COMMON THEME THAT UNDERLIES INITIATION AND PROGRESSION OF CARDIOVASCULAR DISEASE. IN THIS REGARD, MONOCYTES/MACROPHAGES ARE KEY PLAYERS IN THE DEVELOPMENT OF A CHRONIC INFLAMMATORY STATE. OVER THE PAST DECADE, EPIGENETIC MODIFICATIONS, SUCH AS DNA METHYLATION AND POSTTRANSLATIONAL HISTONE PROCESSING, HAVE EMERGED AS IMPORTANT REGULATORS OF IMMUNE CELL PHENOTYPES. ACCUMULATING STUDIES REVEAL THE IMPORTANCE OF EPIGENETIC ENZYMES IN THE DYNAMIC REGULATION OF KEY SIGNALING PATHWAYS THAT ALTER MONOCYTE/MACROPHAGE PHENOTYPES IN RESPONSE TO ENVIRONMENTAL STIMULI. IN THIS REVIEW, WE HIGHLIGHT THE CURRENT PARADIGMS OF MONOCYTE/MACROPHAGE POLARIZATION AND THE EMERGING ROLE OF EPIGENETIC MODIFICATION IN THE REGULATION OF MONOCYTE/MACROPHAGE PHENOTYPE IN OBESITY, DIABETES MELLITUS, ATHEROSCLEROSIS, AND ABDOMINAL AORTIC ANEURYSMS. 2019 8 5423 31 REGULATION OF MACROPHAGE ACTIVATION AND DIFFERENTIATION IN ATHEROSCLEROSIS. CHRONIC INFLAMMATION IS A HALLMARK OF ATHEROSCLEROSIS AND MACROPHAGES PLAY A CENTRAL ROLE IN CONTROLLING INFLAMMATION AT ALL STAGES OF ATHEROSCLEROSIS. IN ATHEROSCLEROSIS, MACROPHAGES AND MONOCYTE-DERIVED MACROPHAGES ARE CONTINUOUSLY EXPOSED TO CHOLESTEROL, OXIDIZED LIPIDS, CELL DEBRIS, CYTOKINES, AND CHEMOKINES. NOT ONLY DO THESE STIMULI INDUCE A SPECIFIC MACROPHAGE PHENOTYPE, BUT THEY ALSO INTERACT EXTENSIVELY, LEADING TO MACROPHAGE HETEROGENEITY IN ATHEROSCLEROTIC PLAQUES. HEREIN, WE REVIEW THE DIVERSE PHENOTYPES OF MACROPHAGES, THE MECHANISMS UNDERLYING MACROPHAGE ACTIVATION, AND THE CONTRIBUTIONS OF MACROPHAGES TO ATHEROSCLEROSIS IN THIS CONTEXT. WE ALSO SUMMARIZE RECENT STUDIES ON FOAMY MACROPHAGES AND MONOCYTE-DERIVED MACROPHAGES IN PLAQUE DURING DISEASE PROGRESSION. WE PROVIDE A COMPREHENSIVE OVERVIEW OF TRANSCRIPTIONAL, EPIGENETIC, AND METABOLIC REPROGRAMMING OF MACROPHAGES AND DISCUSS THE EMERGING CONCEPTS OF TARGETING CYTOKINES AND MACROPHAGES TO MODULATE ATHEROSCLEROSIS. 2021 9 5931 37 TARGETING EPIGENETIC MODIFIERS TO REPROGRAMME MACROPHAGES IN NON-RESOLVING INFLAMMATION-DRIVEN ATHEROSCLEROSIS. EPIGENOMIC AND EPIGENETIC RESEARCH HAS BEEN PROVIDING SEVERAL NEW INSIGHTS INTO A VARIETY OF DISEASES CAUSED BY NON-RESOLVING INFLAMMATION, INCLUDING CARDIOVASCULAR DISEASES. ATHEROSCLEROSIS (AS) HAS LONG BEEN RECOGNIZED AS A CHRONIC INFLAMMATORY DISEASE OF THE ARTERIAL WALLS, CHARACTERIZED BY LOCAL PERSISTENT AND STEPWISE ACCELERATING INFLAMMATION WITHOUT RESOLUTION, ALSO KNOWN AS UNCONTROLLED INFLAMMATION. THE PATHOGENESIS OF AS IS DRIVEN PRIMARILY BY HIGHLY PLASTIC MACROPHAGES VIA THEIR POLARIZATION TO PRO- OR ANTI-INFLAMMATORY PHENOTYPES AS WELL AS OTHER NOVEL SUBTYPES RECENTLY IDENTIFIED BY SINGLE-CELL SEQUENCING. ALTHOUGH EMERGING EVIDENCE HAS INDICATED THE KEY ROLE OF THE EPIGENETIC MACHINERY IN THE REGULATION OF MACROPHAGE PLASTICITY, THE INVESTIGATION OF EPIGENETIC ALTERATIONS AND MODIFIERS IN AS AND RELATED INFLAMMATION IS STILL IN ITS INFANCY. AN INCREASING NUMBER OF THE EPIGENETIC MODIFIERS (E.G. TET2, DNMT3A, HDAC3, HDAC9, JMJD3, KDM4A) HAVE BEEN IDENTIFIED IN EPIGENETIC REMODELLING OF MACROPHAGES THROUGH DNA METHYLATION OR HISTONE MODIFICATIONS (E.G. METHYLATION, ACETYLATION, AND RECENTLY LACTYLATION) IN INFLAMMATION. THESE OR MANY UNEXPLORED MODIFIERS FUNCTION TO DETERMINE OR SWITCH THE DIRECTION OF MACROPHAGE POLARIZATION VIA TRANSCRIPTIONAL REPROGRAMMING OF GENE EXPRESSION AND INTRACELLULAR METABOLIC REWIRING UPON MICROENVIRONMENTAL CUES, THEREBY REPRESENTING A PROMISING TARGET FOR ANTI-INFLAMMATORY THERAPY IN AS. HERE, WE REVIEW UP-TO-DATE FINDINGS INVOLVING THE EPIGENETIC REGULATION OF MACROPHAGES TO SHED LIGHT ON THE MECHANISM OF UNCONTROLLED INFLAMMATION DURING AS ONSET AND PROGRESSION. WE ALSO DISCUSS CURRENT CHALLENGES FOR DEVELOPING AN EFFECTIVE AND SAFE ANTI-AS THERAPY THAT TARGETS THE EPIGENETIC MODIFIERS AND PROPOSE A POTENTIAL ANTI-INFLAMMATORY STRATEGY THAT REPOLARIZES MACROPHAGES FROM PRO- TO ANTI-INFLAMMATORY PHENOTYPES. 2021 10 2532 36 EPIGENETICS IN ATHEROSCLEROSIS AND INFLAMMATION. ATHEROSCLEROSIS IS A MULTIFACTORIAL DISEASE WITH A SEVERE BURDEN ON WESTERN SOCIETY. RECENT INSIGHTS INTO THE PATHOGENESIS OF ATHEROSCLEROSIS UNDERSCORE THE IMPORTANCE OF CHRONIC INFLAMMATION IN BOTH THE INITIATION AND PROGRESSION OF VASCULAR REMODELLING. EXPRESSION OF IMMUNOREGULATORY MOLECULES BY VASCULAR WALL COMPONENTS WITHIN THE ATHEROSCLEROTIC LESIONS IS ACCORDINGLY THOUGHT TO CONTRIBUTE TO THE ONGOING INFLAMMATORY PROCESS. BESIDES GENE REGULATORY PROTEINS (TRANSCRIPTION FACTORS), EPIGENETIC MECHANISMS ALSO PLAY AN ESSENTIAL AND FUNDAMENTAL ROLE IN THE TRANSCRIPTIONAL CONTROL OF GENE EXPRESSION. THESE EPIGENETIC MECHANISMS CHANGE THE ACCESSIBILITY OF CHROMATIN BY DNA METHYLATION AND HISTONE MODIFICATIONS. EPIGENETIC MODULATORS ARE THUS CRITICALLY INVOLVED IN THE REGULATION OF VASCULAR, IMMUNE AND TISSUE-SPECIFIC GENE EXPRESSION WITHIN THE ATHEROSCLEROTIC LESION. IMPORTANTLY, EPIGENETIC PROCESSES ARE REVERSIBLE AND MAY PROVIDE AN EXCELLENT THERAPEUTIC TARGET. THE CONCEPT OF EPIGENETIC REGULATION IS GRADUALLY BEING RECOGNIZED AS AN IMPORTANT FACTOR IN THE PATHOGENESIS OF ATHEROSCLEROSIS. RECENT RESEARCH PROVIDES AN ESSENTIAL LINK BETWEEN INFLAMMATION AND REPROGRAMMING OF THE EPIGENOME. IN THIS REVIEW WE THEREFORE DISCUSS THE BASIS OF EPIGENETIC REGULATION - AND THE CONTRIBUTION THEREOF IN THE REGULATION OF INFLAMMATORY PROCESSES IN GENERAL AND DURING ATHEROSCLEROSIS IN PARTICULAR. MOREOVER WE HIGHLIGHT POTENTIAL THERAPEUTIC INTERVENTIONS BASED ON EPIGENETIC MECHANISMS. 2010 11 2344 25 EPIGENETIC REGULATION OF MACROPHAGES: FROM HOMEOSTASIS MAINTENANCE TO HOST DEFENSE. MACROPHAGES ARE CRUCIAL MEMBERS OF THE INNATE IMMUNE RESPONSE AND IMPORTANT REGULATORS. THE DIFFERENTIATION AND ACTIVATION OF MACROPHAGES REQUIRE THE TIMELY REGULATION OF GENE EXPRESSION, WHICH DEPENDS ON THE INTERACTION OF A VARIETY OF FACTORS, INCLUDING TRANSCRIPTION FACTORS AND EPIGENETIC MODIFICATIONS. EPIGENETIC CHANGES ALSO GIVE MACROPHAGES THE ABILITY TO SWITCH RAPIDLY BETWEEN CELLULAR PROGRAMS, INDICATING THE ABILITY OF EPIGENETIC MECHANISMS TO AFFECT PHENOTYPE PLASTICITY. IN THIS REVIEW, WE FOCUS ON KEY EPIGENETIC EVENTS ASSOCIATED WITH MACROPHAGE FATE, HIGHLIGHTING EVENTS RELATED TO THE MAINTENANCE OF TISSUE HOMEOSTASIS, RESPONSES TO DIFFERENT STIMULI AND THE FORMATION OF INNATE IMMUNE MEMORY. FURTHER UNDERSTANDING OF THE EPIGENETIC REGULATION OF MACROPHAGES WILL BE HELPFUL FOR MAINTAINING TISSUE INTEGRITY, PREVENTING CHRONIC INFLAMMATORY DISEASES AND DEVELOPING THERAPIES TO ENHANCE HOST DEFENSE. 2020 12 6501 29 TRAINED IMMUNITY: LINKING OBESITY AND CARDIOVASCULAR DISEASE ACROSS THE LIFE-COURSE? OBESITY, A CHRONIC INFLAMMATORY DISEASE, IS THE MOST PREVALENT MODIFIABLE RISK FACTOR FOR CARDIOVASCULAR DISEASE. THE MECHANISMS UNDERLYING INFLAMMATION IN OBESITY ARE INCOMPLETELY UNDERSTOOD. RECENT DEVELOPMENTS HAVE CHALLENGED THE DOGMA OF IMMUNOLOGICAL MEMORY OCCURRING EXCLUSIVELY IN THE ADAPTIVE IMMUNE SYSTEM AND SHOW THAT THE INNATE IMMUNE SYSTEM HAS POTENTIAL TO BE REPROGRAMMED. THIS INNATE IMMUNE MEMORY (TRAINED IMMUNITY) IS CHARACTERIZED BY EPIGENETIC AND METABOLIC REPROGRAMMING OF MYELOID CELLS FOLLOWING ENDOGENOUS OR EXOGENOUS STIMULATION, RESULTING IN ENHANCED INFLAMMATION TO SUBSEQUENT STIMULI. TRAINED IMMUNITY PHENOTYPES HAVE NOW BEEN REPORTED FOR OTHER IMMUNE AND NON-IMMUNE CELLS. HERE, WE PROVIDE A NOVEL PERSPECTIVE ON THE PUTATIVE ROLE OF TRAINED IMMUNITY IN MEDIATING THE ADVERSE CARDIOVASCULAR EFFECTS OF OBESITY AND HIGHLIGHT POTENTIAL TRANSLATIONAL PATHWAYS. 2020 13 6452 33 THERAPIES TARGETING TRAINED IMMUNE CELLS IN INFLAMMATORY AND AUTOIMMUNE DISEASES. THE CONCEPT OF TRAINED IMMUNITY HAS RECENTLY EMERGED AS A MECHANISM CONTRIBUTING TO SEVERAL IMMUNE MEDIATED INFLAMMATORY CONDITIONS. TRAINED IMMUNITY IS DEFINED BY THE IMMUNOLOGICAL MEMORY DEVELOPED IN INNATE IMMUNE CELLS AFTER A PRIMARY NON-SPECIFIC STIMULUS THAT, IN TURN, PROMOTES A HEIGHTENED INFLAMMATORY RESPONSE UPON A SECONDARY CHALLENGE. THE MOST CHARACTERISTIC CHANGES ASSOCIATED TO THIS PROCESS INVOLVE THE REWIRING OF CELL METABOLISM AND EPIGENETIC REPROGRAMMING. UNDER PHYSIOLOGICAL CONDITIONS, THE ROLE OF TRAINED IMMUNE CELLS ENSURES A PROMPT RESPONSE. THIS ACTION IS LIMITED BY EFFECTIVE RESOLUTION OF INFLAMMATION AND TISSUE REPAIR IN ORDER TO RESTORE HOMEOSTASIS. HOWEVER, UNRESTRAINED ACTIVATION OF INNATE IMMUNE CELLS CONTRIBUTES TO THE DEVELOPMENT OF CHRONIC INFLAMMATION AND TISSUE DESTRUCTION THROUGH THE SECRETION OF INFLAMMATORY CYTOKINES, PROTEASES AND GROWTH FACTORS. THEREFORE, INTERVENTIONS AIMED AT REVERSING THE CHANGES INDUCED BY TRAINED IMMUNITY PROVIDE POTENTIAL THERAPEUTIC APPROACHES TO TREAT INFLAMMATORY AND AUTOIMMUNE DISEASES LIKE RHEUMATOID ARTHRITIS (RA). WE REVIEW CELLULAR APPROACHES THAT TARGET METABOLISM AND THE EPIGENETIC REPROGRAMMING OF DENDRITIC CELLS, MACROPHAGES, NATURAL KILLER CELLS, AND OTHER TRAINED CELLS IN THE CONTEXT OF AUTOIMMUNE INFLAMMATORY DISEASES. 2020 14 4043 28 MACROPHAGES IN CHRONIC LIVER FAILURE: DIVERSITY, PLASTICITY AND THERAPEUTIC TARGETING. CHRONIC LIVER INJURY RESULTS IN IMMUNE-DRIVEN PROGRESSIVE FIBROSIS, WITH RISK OF CIRRHOSIS DEVELOPMENT AND IMPACT ON MORBIDITY AND MORTALITY. PERSISTENT LIVER CELL DAMAGE AND DEATH CAUSES IMMUNE CELL ACTIVATION AND INFLAMMATION. PATIENTS WITH ADVANCED CIRRHOSIS ADDITIONALLY EXPERIENCE PATHOLOGICAL BACTERIAL TRANSLOCATION, EXPOSURE TO MICROBIAL PRODUCTS AND CHRONIC ENGAGEMENT OF THE IMMUNE SYSTEM. BACTERIAL INFECTIONS HAVE A HIGH INCIDENCE IN CIRRHOSIS, WITH SPONTANEOUS BACTERIAL PERITONITIS BEING THE MOST COMMON, WHILE THE SUBSEQUENT SYSTEMIC INFLAMMATION, ORGAN FAILURE AND IMMUNE DYSREGULATION INCREASE THE MORTALITY RISK. TISSUE-RESIDENT AND RECRUITED MACROPHAGES PLAY A CENTRAL PART IN THE DEVELOPMENT OF INFLAMMATION AND FIBROSIS PROGRESSION. IN THE LIVER, ADIPOSE TISSUE, PERITONEUM AND INTESTINES, DIVERSE MACROPHAGE POPULATIONS EXHIBIT GREAT PHENOTYPIC AND FUNCTIONAL PLASTICITY DETERMINED BY THEIR ONTOGENY, EPIGENETIC PROGRAMMING AND LOCAL MICROENVIRONMENT. THESE CHANGES CAN, AT DIFFERENT TIMES, PROMOTE OR AMELIORATE DISEASE STATES AND THEREFORE REPRESENT POTENTIAL TARGETS FOR MACROPHAGE-DIRECTED THERAPIES. IN THIS REVIEW, WE DISCUSS THE EVIDENCE FOR MACROPHAGE PHENOTYPIC AND FUNCTIONAL ALTERATIONS IN TISSUE COMPARTMENTS DURING THE DEVELOPMENT AND PROGRESSION OF CHRONIC LIVER FAILURE IN DIFFERENT AETIOLOGIES AND HIGHLIGHT THE POTENTIAL OF MACROPHAGE MODULATION AS A THERAPEUTIC STRATEGY FOR LIVER DISEASE. 2021 15 2343 23 EPIGENETIC REGULATION OF MACROPHAGE POLARIZATION IN CARDIOVASCULAR DISEASES. CARDIOVASCULAR DISEASES (CVDS) ARE THE LEADING CAUSE OF HOSPITALIZATION AND DEATH WORLDWIDE, ESPECIALLY IN DEVELOPING COUNTRIES. THE INCREASED PREVALENCE RATE AND MORTALITY DUE TO CVDS, DESPITE THE DEVELOPMENT OF SEVERAL APPROACHES FOR PREVENTION AND TREATMENT, ARE ALARMING TRENDS IN GLOBAL HEALTH. CHRONIC INFLAMMATION AND MACROPHAGE INFILTRATION ARE KEY REGULATORS OF THE INITIATION AND PROGRESSION OF CVDS. RECENT DATA SUGGEST THAT EPIGENETIC MODIFICATIONS, SUCH AS DNA METHYLATION, POSTTRANSLATIONAL HISTONE MODIFICATIONS, AND RNA MODIFICATIONS, REGULATE CELL DEVELOPMENT, DNA DAMAGE REPAIR, APOPTOSIS, IMMUNITY, CALCIUM SIGNALING, AND AGING IN CARDIOMYOCYTES; AND ARE INVOLVED IN MACROPHAGE POLARIZATION AND CONTRIBUTE SIGNIFICANTLY TO CARDIAC DISEASE DEVELOPMENT. CARDIAC MACROPHAGES NOT ONLY TRIGGER DAMAGING INFLAMMATORY RESPONSES DURING ATHEROSCLEROTIC PLAQUE FORMATION, MYOCARDIAL INJURY, AND HEART FAILURE BUT ARE ALSO INVOLVED IN TISSUE REPAIR, REMODELING, AND REGENERATION. IN THIS REVIEW, WE SUMMARIZE THE KEY EPIGENETIC MODIFICATIONS THAT INFLUENCE MACROPHAGE POLARIZATION AND CONTRIBUTE TO THE PATHOPHYSIOLOGY OF CVDS, AND HIGHLIGHT THEIR POTENTIAL FOR THE DEVELOPMENT OF ADVANCED EPIGENETIC THERAPIES. 2023 16 2289 26 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 17 3965 25 LONG NONCODING RNAS IN THE METABOLIC CONTROL OF INFLAMMATION AND IMMUNE DISORDERS. THE METABOLIC CONTROL OF IMMUNE CELL DEVELOPMENT AND FUNCTION HAS BEEN SHOWN TO BE CRITICAL FOR THE MAINTENANCE OF IMMUNE HOMEOSTASIS AND IS ALSO INVOLVED IN THE PATHOGENESIS OF IMMUNE DISORDERS. PATHOGENIC INFECTIONS OR CANCERS MAY INDUCE METABOLIC REPROGRAMMING THROUGH DIFFERENT PATHWAYS TO MEET THE ENERGY AND METABOLITE DEMANDS FOR PATHOGEN PROPAGATION OR CANCER PROGRESSION. IN ADDITION, SOME DEREGULATED METABOLITES COULD TRIGGER OR REGULATE IMMUNE RESPONSES, THUS CAUSING CHRONIC INFLAMMATION OR IMMUNE DISORDERS, SUCH AS VIRAL INFECTION, CANCER AND OBESITY. THEREFORE, THE METHODS THROUGH WHICH METABOLISM IS REGULATED AND THE ROLE OF METABOLIC REGULATION IN INFLAMMATION AND IMMUNITY ATTRACT MUCH ATTENTION. EPIGENETIC REGULATION OF INFLAMMATION AND IMMUNITY IS AN EMERGING FIELD. LONG NONCODING RNAS (LNCRNAS) HAVE BEEN WELL DOCUMENTED TO PLAY CRUCIAL ROLES IN MANY BIOLOGICAL PROCESSES THROUGH DIVERSE MECHANISMS, INCLUDING IMMUNE REGULATION AND METABOLIC ALTERNATION. HERE, WE REVIEW THE FUNCTIONS AND MECHANISMS OF LNCRNAS IN THE METABOLIC REGULATION OF INFLAMMATORY IMMUNE DISORDERS, AIMING TO DEEPEN OUR UNDERSTANDING OF THE EPIGENETIC REGULATION OF INFLAMMATION AND IMMUNITY. 2019 18 6006 33 THE ALTERATIONS IN AND THE ROLE OF THE TH17/TREG BALANCE IN METABOLIC DISEASES. CHRONIC INFLAMMATION PLAYS AN IMPORTANT ROLE IN THE DEVELOPMENT OF METABOLIC DISEASES. THESE INCLUDE OBESITY, TYPE 2 DIABETES MELLITUS, AND METABOLIC DYSFUNCTION-ASSOCIATED FATTY LIVER DISEASE. THE PROINFLAMMATORY ENVIRONMENT MAINTAINED BY THE INNATE IMMUNITY, INCLUDING MACROPHAGES AND RELATED CYTOKINES, CAN BE INFLUENCED BY ADAPTIVE IMMUNITY. THE FUNCTION OF T HELPER 17 (TH17) AND REGULATORY T (TREG) CELLS IN THIS PROCESS HAS ATTRACTED ATTENTION. THE TH17/TREG BALANCE IS REGULATED BY INFLAMMATORY CYTOKINES AND VARIOUS METABOLIC FACTORS, INCLUDING THOSE ASSOCIATED WITH CELLULAR ENERGY METABOLISM. THE POSSIBLE UNDERLYING MECHANISMS INCLUDE METABOLISM-RELATED SIGNALING PATHWAYS AND EPIGENETIC REGULATION. SEVERAL STUDIES CONDUCTED ON HUMAN AND ANIMAL MODELS HAVE SHOWN MARKED DIFFERENCES IN AND THE IMPORTANT ROLES OF TH17/TREG IN CHRONIC INFLAMMATION ASSOCIATED WITH OBESITY AND METABOLIC DISEASES. MOREOVER, TH17/TREG SEEMS TO BE A BRIDGE LINKING THE GUT MICROBIOTA TO HOST METABOLIC DISORDERS. IN THIS REVIEW, WE HAVE PROVIDED AN OVERVIEW OF THE ALTERATIONS IN AND THE FUNCTIONS OF THE TH17/TREG BALANCE IN METABOLIC DISEASES AND ITS ROLE IN REGULATING IMMUNE RESPONSE-RELATED GLUCOSE AND LIPID METABOLISM. 2021 19 3544 33 IMMUNOMETABOLIC CONTROL OF TRAINED IMMUNITY. INNATE IMMUNE CELLS CAN ADOPT LONG-TERM INFLAMMATORY PHENOTYPES FOLLOWING BRIEF ENCOUNTERS WITH EXOGENOUS (MICROBIAL) OR ENDOGENOUS STIMULI. THIS PHENOMENON IS NAMED TRAINED IMMUNITY AND CAN IMPROVE HOST DEFENSE AGAINST (RECURRENT) INFECTIONS. IN CONTRAST, TRAINED IMMUNITY CAN ALSO BE MALADAPTIVE IN THE CONTEXT OF CHRONIC INFLAMMATORY DISORDERS, SUCH AS ATHEROSCLEROSIS. KEY TO FUTURE THERAPEUTIC EXPLOITATION OF THIS MECHANISM IS THOROUGH KNOWLEDGE OF THE MECHANISMS DRIVING TRAINED IMMUNITY, WHICH CAN BE USED AS PHARMACOLOGICAL TARGETS. THESE MECHANISMS INCLUDE PROFOUND CHANGES IN INTRACELLULAR METABOLISM, WHICH ARE CLOSELY INTERTWINED WITH EPIGENETIC REPROGRAMMING AT THE LEVEL OF HISTONE MODIFICATIONS. GLYCOLYSIS, GLUTAMINE REPLENISHMENT OF THE TRICARBOXYLIC ACID CYCLE WITH ACCUMULATION OF FUMARATE, AND THE MEVALONATE PATHWAY HAVE ALL BEEN IDENTIFIED AS CRITICAL PATHWAYS FOR TRAINED IMMUNITY IN MONOCYTES AND MACROPHAGES. IN THIS REVIEW, WE PROVIDE A STATE-OF-THE-ART OVERVIEW OF HOW THESE METABOLIC PATHWAYS INTERACT WITH EPIGENETIC PROGRAMS TO DEVELOP TRAINED IMMUNITY. 2021 20 2342 26 EPIGENETIC REGULATION OF MACROPHAGE POLARIZATION AND FUNCTION. MACROPHAGE POLARIZATION REFERS TO DEVELOPMENT OF A SPECIFIC PHENOTYPE IMPORTANT FOR TISSUE HOMEOSTASIS OR HOST DEFENSE IN RESPONSE TO ENVIRONMENTAL CUES. ENVIRONMENTAL FACTORS THAT INDUCE MACROPHAGE POLARIZATION INCLUDE CYTOKINES AND MICROBIAL FACTORS PRODUCED BY PATHOGENS OR COMMENSAL MICROBIOTA. SIGNALING PATHWAYS UTILIZED BY THESE POLARIZING FACTORS HAVE BEEN WELL CHARACTERIZED, BUT IT IS LESS CLEAR HOW SIGNALS ARE CONVERTED INTO COMPLEX AND SUSTAINED PATTERNS OF GENE EXPRESSION, AND HOW MACROPHAGES ARE REPROGRAMMED DURING POLARIZATION TO ALTER THEIR RESPONSES TO SUBSEQUENT ENVIRONMENTAL CHALLENGES. EMERGING EVIDENCE, REVIEWED HERE, SUGGESTS AN IMPORTANT ROLE FOR EPIGENETIC MECHANISMS IN MODULATING AND TRANSMITTING SIGNALS DURING MACROPHAGE POLARIZATION AND REPROGRAMMING. DEEPER UNDERSTANDING OF EPIGENETIC REGULATION OF MACROPHAGE PHENOTYPE WILL ENABLE DEVELOPMENT OF GENE-SPECIFIC THERAPEUTIC APPROACHES TO ENHANCE HOST DEFENSE WHILE PRESERVING TISSUE INTEGRITY AND PREVENTING CHRONIC INFLAMMATORY DISEASES. 2013