1 3734 116 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 2 3544 45 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 3 6501 43 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 4 6502 46 TRAINED IMMUNITY: LONG-TERM ADAPTATION IN INNATE IMMUNE RESPONSES. ADAPTIVE IMMUNE RESPONSES ARE CHARACTERIZED BY ANTIGEN SPECIFICITY AND INDUCTION OF LIFELONG IMMUNOLOGIC MEMORY. RECENTLY, IT HAS BEEN REPORTED THAT INNATE IMMUNE CELLS CAN ALSO BUILD IMMUNE MEMORY CHARACTERISTICS-A PROCESS TERMED TRAINED IMMUNITY. TRAINED IMMUNITY DESCRIBES THE PERSISTENT HYPERRESPONSIVE PHENOTYPE THAT INNATE IMMUNE CELLS CAN DEVELOP AFTER BRIEF STIMULATION. PATHOGENIC STIMULI SUCH AS MICROORGANISMS, AND ALSO ENDOGENOUS MOLECULES INCLUDING URIC ACID, OXIDIZED LDL (LOW-DENSITY LIPOPROTEIN), AND CATECHOLAMINES, ARE CAPABLE OF INDUCING MEMORY IN MONOCYTES AND MACROPHAGES. WHILE TRAINED IMMUNITY PROVIDES FAVORABLE CROSS-PROTECTION IN THE CONTEXT OF INFECTIOUS DISEASES, THE HEIGHTENED IMMUNE RESPONSE CAN BE MALADAPTIVE IN DISEASES DRIVEN BY CHRONIC SYSTEMIC INFLAMMATION, SUCH AS ATHEROSCLEROSIS. TRAINED IMMUNITY IS MAINTAINED BY DISTINCT EPIGENETIC AND METABOLIC MECHANISMS AND PERSISTS FOR AT LEAST SEVERAL MONTHS IN VIVO DUE TO REPROGRAMMING OF MYELOID PROGENITOR CELLS. ADDITIONALLY, CERTAIN NONIMMUNE CELLS ARE ALSO FOUND TO EXHIBIT TRAINED IMMUNITY CHARACTERISTICS. THUS, TRAINED IMMUNITY PRESENTS AN EXCITING FRAMEWORK TO DEVELOP NEW APPROACHES TO VACCINATION AND ALSO NOVEL PHARMACOLOGICAL TARGETS IN THE TREATMENT OF INFLAMMATORY DISEASES. 2021 5 6493 57 TRAINED IMMUNITY AND REACTIVITY OF MACROPHAGES AND ENDOTHELIAL CELLS. INNATE IMMUNE CELLS CAN DEVELOP EXACERBATED IMMUNOLOGIC RESPONSE AND LONG-TERM INFLAMMATORY PHENOTYPE FOLLOWING BRIEF EXPOSURE TO ENDOGENOUS OR EXOGENOUS INSULTS, WHICH LEADS TO AN ALTERED RESPONSE TOWARDS A SECOND CHALLENGE AFTER THE RETURN TO A NONACTIVATED STATE. THIS PHENOMENON IS KNOWN AS TRAINED IMMUNITY (TI). TI IS NOT ONLY IMPORTANT FOR HOST DEFENSE AND VACCINE RESPONSE BUT ALSO FOR CHRONIC INFLAMMATIONS SUCH AS CARDIOVASCULAR AND METABOLIC DISEASES SUCH AS ATHEROSCLEROSIS. TI CAN OCCUR IN INNATE IMMUNE CELLS SUCH AS MONOCYTES/MACROPHAGES, NATURAL KILLER CELLS, ENDOTHELIAL CELLS (ECS), AND NONIMMUNE CELLS, SUCH AS FIBROBLAST. IN THIS BRIEF REVIEW, WE ANALYZE THE SIGNIFICANCE OF TI IN ECS, WHICH ARE ALSO CONSIDERED AS INNATE IMMUNE CELLS IN ADDITION TO MACROPHAGES. TI CAN BE INDUCED BY A VARIETY OF STIMULI, INCLUDING LIPOPOLYSACCHARIDES, BCG (BACILLUS CALMETTE-GUERIN), AND OXLDL (OXIDIZED LOW-DENSITY LIPOPROTEIN), WHICH ARE DEFINED AS RISK FACTORS FOR CARDIOVASCULAR AND METABOLIC DISEASES. FURTHERMORE, TI IN ECS IS FUNCTIONAL FOR INFLAMMATION EFFECTIVENESS AND TRANSITION TO CHRONIC INFLAMMATION. REWIRING OF CELLULAR METABOLISM OF THE TRAINED CELLS TAKES PLACE DURING INDUCTION OF TI, INCLUDING INCREASED GLYCOLYSIS, GLUTAMINOLYSIS, INCREASED ACCUMULATION OF TRICARBOXYLIC ACID CYCLE METABOLITES AND ACETYL-COENZYME A PRODUCTION, AS WELL AS INCREASED MEVALONATE SYNTHESIS. SUBSEQUENTLY, THIS LEADS TO EPIGENETIC REMODELING, RESULTING IN IMPORTANT CHANGES IN CHROMATIN ARCHITECTURE THAT ENABLES INCREASED GENE TRANSCRIPTION AND ENHANCED PROINFLAMMATORY IMMUNE RESPONSE. HOWEVER, TI PATHWAYS AND INFLAMMATORY PATHWAYS ARE SEPARATED TO ENSURE MEMORY STAYS WHEN INFLAMMATION UNDERGOES RESOLUTION. ADDITIONALLY, REACTIVE OXYGEN SPECIES PLAY CONTEXT-DEPENDENT ROLES IN TI. THEREFORE, TI PLAYS SIGNIFICANT ROLES IN EC AND MACROPHAGE PATHOLOGY AND CHRONIC INFLAMMATION. HOWEVER, FURTHER CHARACTERIZATION OF TI IN ECS AND MACROPHAGES WOULD PROVIDE NOVEL INSIGHTS INTO CARDIOVASCULAR DISEASE PATHOGENESIS AND NEW THERAPEUTIC TARGETS. GRAPHIC ABSTRACT: A GRAPHIC ABSTRACT IS AVAILABLE FOR THIS ARTICLE. 2021 6 2468 31 EPIGENETIC TOXICOLOGY AS TOXICANT-INDUCED CHANGES IN INTRACELLULAR SIGNALLING LEADING TO ALTERED GAP JUNCTIONAL INTERCELLULAR COMMUNICATION. COMMUNICATION MECHANISMS [EXTRA-, INTRA-, AND GAP JUNCTIONAL INTER-CELLULAR COMMUNICATION (GJIC)] CONTROL, FROM THE FERTILIZED EGG, THROUGH EMBRYOGENESIS TO MATURITY AND AGING, WHETHER A CELL PROLIFERATES, DIFFERENTIATES, DIES BY APOPTOSIS, OR IF DIFFERENTIATED, ADAPTIVELY RESPONDS TO ENDOGENOUS AND EXOGENOUS SIGNALS. FROM THE EGG TO THE 100 TRILLION CELLS IN THE HUMAN BODY, HEALTH IS MAINTAINED WHEN THESE COMMUNICATION PROCESSES BETWEEN STEM, PROGENITOR AND TERMINALLY DIFFERENTIATED CELLS ARE INTEGRATED. EACH CELL CHOICE INVOLVES 'EPIGENETIC' MECHANISMS TO ALTER THE EXPRESSION OF GENES AT THE TRANSCRIPTIONAL, TRANSLATIONAL OR POST-TRANSLATIONAL LEVELS. DISRUPTION OF THE COMMUNICATION MECHANISMS CAN BE EITHER ADAPTIVE OR MALADAPTIVE. MODULATION OF EXTRA-CELLULAR COMMUNICATION, EITHER BY GENETIC IMBALANCES OF GROWTH FACTORS, HORMONES OR NEUROTRANSMITTERS OR BY ENVIRONMENTAL, EXOGENOUS CHEMICALS CAN TRIGGER SIGNAL TRANSDUCING INTRA-CELLULAR MECHANISMS. THESE INTRA-CELLULAR SIGNALS CAN MODULATE GENE EXPRESSION AT THE TRANSCRIPTIONAL, TRANSLATIONAL OR POST-TRANSLATIONAL LEVELS WHILE ALSO MODULATING GJIC. UNTIMELY OR CHRONIC DISRUPTION OF GJIC DURING EMBRYONIC OR FETAL DEVELOPMENT COULD LEAD TO EMBRYONIC LETHALITY OR TERATOGENESIS. BY MODULATION OF GJIC, HOMEOSTATIC CONTROL OF CELL GROWTH, DIFFERENTIATION OR APOPTOSIS COULD LEAD TO SPECIFIC DISEASES, SUCH AS NEUROLOGICAL, CARDIOVASCULAR, REPRODUCTIVE OR ENDOCRINOLOGICAL DYSFUNCTION. CHEMICAL MODULATION OR ONCOGENE DOWN-REGULATION OF GJIC IN INITIATED TISSUES HAS BEEN SHOWN TO LEAD TO TUMOR PROMOTION. GENETIC SYNDROMES CARRYING A MUTATED GAP JUNCTION GENE, TOGETHER WITH SOME TRANSGENIC AND KNOCK-OUT GAP JUNCTION GENE MICE, PROVIDE EVIDENCE FOR THE IMPORTANCE OF THIS ORGANELLE FOUND ONLY IN METAZOANS. IMPLICATIONS FOR 'THRESHOLDS' TO TOXICANTS AND FOR RISK ASSESSMENT ARE EVIDENT. 1998 7 6376 38 THE ROLE OF NEUTROPHILS IN TRAINED IMMUNITY. THE PRINCIPLE OF TRAINED IMMUNITY REPRESENTS INNATE IMMUNE MEMORY DUE TO SUSTAINED, MAINLY EPIGENETIC, CHANGES TRIGGERED BY ENDOGENOUS OR EXOGENOUS STIMULI IN BONE MARROW (BM) PROGENITORS (CENTRAL TRAINED IMMUNITY) AND THEIR INNATE IMMUNE CELL PROGENY, THEREBY TRIGGERING ELEVATED RESPONSIVENESS AGAINST SECONDARY STIMULI. BM PROGENITORS CAN RESPOND TO MICROBIAL AND STERILE SIGNALS, THEREBY POSSIBLY ACQUIRING TRAINED IMMUNITY-MEDIATED LONG-LASTING ALTERATIONS THAT MAY SHAPE THE FATE AND FUNCTION OF THEIR PROGENY, FOR EXAMPLE, NEUTROPHILS. NEUTROPHILS, THE MOST ABUNDANT INNATE IMMUNE CELL POPULATION, ARE PRODUCED IN THE BM FROM COMMITTED PROGENITOR CELLS IN A PROCESS DESIGNATED GRANULOPOIESIS. NEUTROPHILS ARE THE FIRST RESPONDERS AGAINST INFECTIOUS OR INFLAMMATORY CHALLENGES AND HAVE VERSATILE FUNCTIONS IN IMMUNITY. TOGETHER WITH OTHER INNATE IMMUNE CELLS, NEUTROPHILS ARE EFFECTORS OF PERIPHERAL TRAINED IMMUNITY. HOWEVER, GIVEN THE SHORT LIFETIME OF NEUTROPHILS, THEIR ABILITY TO ACQUIRE IMMUNOLOGICAL MEMORY MAY LIE IN THE CENTRAL TRAINING OF THEIR BM PROGENITORS RESULTING IN GENERATION OF REPROGRAMMED, THAT IS, "TRAINED", NEUTROPHILS. ALTHOUGH TRAINED IMMUNITY MAY HAVE BENEFICIAL EFFECTS IN INFECTION OR CANCER, IT MAY ALSO MEDIATE DETRIMENTAL OUTCOMES IN CHRONIC INFLAMMATION. HERE, WE REVIEW THE EMERGING RESEARCH AREA OF TRAINED IMMUNITY WITH A PARTICULAR EMPHASIS ON THE ROLE OF NEUTROPHILS AND GRANULOPOIESIS. 2023 8 567 28 BASIC PROPERTIES AND MOLECULAR MECHANISMS OF EXOGENOUS CHEMICAL CARCINOGENS. EXOGENOUS CHEMICAL CARCINOGENESIS IS AN EXTREMELY COMPLEX MULTIFACTORIAL PROCESS DURING WHICH GENE-ENVIRONMENT INTERACTIONS INVOLVING CHRONIC EXPOSURE TO EXOGENOUS CHEMICAL CARCINOGENS (ECCS) AND POLYMORPHISMS OF CANCER SUSCEPTIBILITY GENES ADD FURTHER COMPLEXITY. WE DESCRIBE THE PROPERTIES AND MOLECULAR MECHANISMS OF ECCS THAT CONTRIBUTE TO INDUCE AND GENERATE CANCER. A BASIC AND SPECIFIC PROPERTY OF MANY LIPOPHILIC ORGANIC ECCS INCLUDING POLYCYCLIC AROMATIC HYDROCARBONS AND POLYHALOGENATED AROMATIC HYDROCARBONS IS THEIR ABILITY TO BIOACCUMULATE IN THE ADIPOSE TISSUE FROM WHERE THEY MAY BE RELEASED IN THE BLOOD CIRCULATION AND TARGET PERIPHERAL TISSUES FOR CARCINOGENESIS. MANY ORGANIC ECCS ARE PROCARCINOGENS AND CONSEQUENTLY NEED TO BE ACTIVATED BY THE CYTOCHROME P450 (CYP) SYSTEM AND/OR OTHER ENZYMES BEFORE THEY CAN ADDUCT DNA AND PROTEINS. BECAUSE THEY CONTRIBUTE NOT ONLY TO THE COCARCINOGENIC AND PROMOTING EFFECTS OF MANY AROMATIC POLLUTANTS BUT ALSO TO THEIR MUTAGENIC EFFECTS, THE ARYL HYDROCARBON RECEPTOR-ACTIVATING AND THE INDUCIBLE CYP SYSTEMS ARE CENTRAL TO EXOGENOUS CHEMICAL CARCINOGENESIS. ANOTHER BASIC PROPERTY OF ECCS IS THEIR ABILITY TO INDUCE STABLE AND BULKY DNA ADDUCTS THAT CANNOT BE SIMPLY REPAIRED BY THE DIFFERENT REPAIR SYSTEMS. IN ADDITION, FOLLOWING ECC EXPOSURE, MUTAGENESIS MAY ALSO BE CAUSED INDIRECTLY BY FREE-RADICAL PRODUCTION AND BY EPIGENETIC ALTERATIONS. AS A RESULT OF COMPLEX MOLECULAR INTERPLAYS, DIRECT AND/OR INDIRECT MUTAGENESIS MAY ESPECIALLY ACCOUNT FOR THE CARCINOGENIC EFFECTS OF MANY EXOGENOUS METALS AND METALLOIDS. BECAUSE OF THESE MOLECULAR PROPERTIES AND ACTION MECHANISMS, WE CONCLUDE THAT ECCS COULD BE MAJOR CONTRIBUTORS TO HUMAN CANCER, WITH OBVIOUSLY GREAT PUBLIC HEALTH CONSEQUENCES. 2010 9 6503 36 TRAINED IMMUNITY: REPROGRAMMING INNATE IMMUNITY IN HEALTH AND DISEASE. TRADITIONALLY, THE INNATE AND ADAPTIVE IMMUNE SYSTEMS ARE DIFFERENTIATED BY THEIR SPECIFICITY AND MEMORY CAPACITY. IN RECENT YEARS, HOWEVER, THIS PARADIGM HAS SHIFTED: CELLS OF THE INNATE IMMUNE SYSTEM APPEAR TO BE ABLE TO GAIN MEMORY CHARACTERISTICS AFTER TRANSIENT STIMULATION, RESULTING IN AN ENHANCED RESPONSE UPON SECONDARY CHALLENGE. THIS PHENOMENON HAS BEEN CALLED TRAINED IMMUNITY. TRAINED IMMUNITY IS CHARACTERIZED BY NONSPECIFIC INCREASED RESPONSIVENESS, MEDIATED VIA EXTENSIVE METABOLIC AND EPIGENETIC REPROGRAMMING. TRAINED IMMUNITY EXPLAINS THE HETEROLOGOUS EFFECTS OF VACCINES, WHICH RESULT IN INCREASED PROTECTION AGAINST SECONDARY INFECTIONS. HOWEVER, IN CHRONIC INFLAMMATORY CONDITIONS, TRAINED IMMUNITY CAN INDUCE MALADAPTIVE EFFECTS AND CONTRIBUTE TO HYPERINFLAMMATION AND PROGRESSION OF CARDIOVASCULAR DISEASE, AUTOINFLAMMATORY SYNDROMES, AND NEUROINFLAMMATION. IN THIS REVIEW WE SUMMARIZE THE CURRENT STATE OF THE FIELD OF TRAINED IMMUNITY, ITS MECHANISMS, AND ITS ROLES IN BOTH HEALTH AND DISEASE. 2021 10 6452 39 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 11 2383 32 EPIGENETIC REGULATOR G9A PROVIDES GLUCOSE AS A SWEET KEY TO STRESS RESISTANCE. THE ABILITY TO ADAPT TO ACUTE AND CHRONIC STRESS IS IMPORTANT FOR ORGANISMS TO THRIVE IN EVOLUTIONARY NICHES AND FOR CELLS TO SURVIVE IN ADVERSE CONDITIONS. THE REGULATORY NETWORKS THAT CONTROL STRESS RESPONSES ARE EVOLUTIONARILY CONSERVED, AND MANY FACTORS THAT SELECTIVELY ACTIVATE STRESS RESPONSES HAVE BEEN IDENTIFIED. LESS WELL UNDERSTOOD ARE MECHANISMS THAT GUARD AGAINST UNNECESSARY INDUCTION OF CYTOPROTECTIVE FACTORS AND THAT CONNECT STRESS RESPONSES WITH CELLULAR METABOLISM TO CONTROL ENERGY EXPENDITURE DURING STRESS. THE WORK OF RIAHI AND COLLEAGUES REPRESENTS IMPORTANT PROGRESS IN THIS REGARD BECAUSE IT IDENTIFIES THE HISTONE METHYLTRANSFERASE G9A AS A MODULATOR OF OXIDATIVE STRESS RESPONSES. G9A DAMPENS THE EXPRESSION OF ANTIOXIDANT GENES, THUS PREVENTING INAPPROPRIATE ENERGY CONSUMPTION. MOREOVER, G9A PROMOTES THE WELL-PACED CATABOLISM OF STORAGE GLYCOGEN AND FAT DURING STRESS. THE IMPORTANCE OF ENERGY AVAILABILITY DURING STRESS IS FURTHER EVIDENCED BY EXOGENOUS GLUCOSE RESCUING THE VULNERABILITY OF THE G9A MUTANT TO OXIDATIVE STRESS. PRIOR WORK IN MULTIPLE MODEL SYSTEMS HAS IMPLICATED G9A IN SEVERAL OTHER ADAPTIVE RESPONSES. THEREFORE, ITS ROLE IN PACING ENERGY CONSUMPTION AND IN RESTRAINING EXCESSIVE STRESS RESPONSE GENE EXPRESSION UNDER STRESS MAY EXTEND TO OTHER ADAPTIVE RESPONSES ACROSS SPECIES. 2019 12 2804 30 FETAL EPIGENETIC MECHANISMS AND INNATE IMMUNITY IN ASTHMA. ALLERGY AND ASTHMA ARE CHRONIC INFLAMMATORY DISEASES THAT RESULT FROM COMPLEX GENE-ENVIRONMENT INTERACTIONS. RECENT EVIDENCE POINTS TO THE IMPORTANCE OF PRENATAL AND POSTNATAL DEVELOPMENTAL PROCESSES IN THE MATURATION OF BALANCED IMMUNE RESPONSES. NOVEL DATA INDICATE THAT EPIGENETIC MECHANISMS CONTRIBUTE TO THE DEVELOPMENT OF T-HELPER-CELL FUNCTION. ENVIRONMENTAL FACTORS, INCLUDING DIESEL EXHAUST PARTICLES, VITAMINS, AND TOBACCO SMOKE, OPERATE THROUGH SUCH MECHANISMS. FURTHERMORE, THE ROLE OF ENVIRONMENTAL MICROBES PROVIDES ANOTHER-AND MAYBE AN EVEN MORE IMPORTANT-GROUP OF EXOGENOUS EXPOSURES THAT OPERATE IN THIS CRITICAL TIME FRAME. A BETTER UNDERSTANDING OF FETAL IMMUNO-MATURATION CONDITIONS WILL PROVIDE THE BASIS FOR THE DEVELOPMENT OF NOVEL ALLERGO-PROTECTIVE CLINICAL STRATEGIES. 2010 13 6497 43 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 14 806 33 CHALLENGES FOR MODELING AND INTERPRETING THE COMPLEX BIOLOGY OF SEVERE INJURY AND INFLAMMATION. HUMAN INJURY IS ASSOCIATED WITH INFLAMMATORY RESPONSES THAT ARE MODULATED BY THE ACUTE AND CHRONIC ACTIVITY OF ENDOGENOUS FACTORS AND EXOGENOUS INTERVENTIONS. A CHARACTERISTIC FEATURE OF CHRONIC, SEVERE INFLAMMATORY STATES IS THE DIMINISHED SIGNAL OUTPUT VARIABILITY OF MANY ORGAN SYSTEMS, INCLUDING INNATE IMMUNE RESPONSIVENESS AND ENDOGENOUS NEURAL AND ENDOCRINE-MEDIATED FUNCTIONS. THE ATTENUATION OF SIGNAL/RESPONSE VARIABILITY AND INTEGRATION OF FEEDBACK CAPACITY MAY CONTRIBUTE TO SYSTEMIC AND TISSUE-SPECIFIC DETERIORATION OF FUNCTION. SOME WELL-INTENTIONED THERAPIES DIRECTED TOWARD SUPPORT OF SYSTEMIC AND TISSUE FUNCTIONS MAY ACTUALLY PROMOTE THE LOSS OF SYSTEM(S) ADAPTABILITY AND CONTRIBUTE TO ADVERSE OUTCOMES IN SEVERELY STRESSED PATIENTS. IN VIVO AND IN SILICO MODELS OF STRESS, INJURY, AND INFECTION HAVE YET TO FULLY DEFINE THE INFLUENCES OF ONGOING STRESSFUL STIMULAE AS WELL AS GENETIC VARIATION AND EPIGENETIC FACTORS IN THE CONTEXT OF AN EVOLVING INFLAMMATORY STATE. EXPERIMENTAL AND HUMAN MODELS INCORPORATING VARIABLE, ANTECEDENT STRESS(ES) AND ALTERED NEUROENDOCRINE RHYTHMS MIGHT APPROXIMATE THE ALTERED ADAPTABILITY IN IMMUNE AND ORGAN FUNCTION RESPONSES. SUCH MODELS MAY ALSO PROVIDE INSIGHTS INTO THE SALIENT MECHANISMS OF RISK AND OUTCOME MORE PRECISELY THAN DO THE CONSTRAINED STUDY CONDITIONS OF CURRENT ANIMAL OR HUMAN MODELS OF SYSTEMIC INFLAMMATION. 2008 15 6504 34 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 16 1310 33 DEFINING TRAINED IMMUNITY AND ITS ROLE IN HEALTH AND DISEASE. IMMUNE MEMORY IS A DEFINING FEATURE OF THE ACQUIRED IMMUNE SYSTEM, BUT ACTIVATION OF THE INNATE IMMUNE SYSTEM CAN ALSO RESULT IN ENHANCED RESPONSIVENESS TO SUBSEQUENT TRIGGERS. THIS PROCESS HAS BEEN TERMED 'TRAINED IMMUNITY', A DE FACTO INNATE IMMUNE MEMORY. RESEARCH IN THE PAST DECADE HAS POINTED TO THE BROAD BENEFITS OF TRAINED IMMUNITY FOR HOST DEFENCE BUT HAS ALSO SUGGESTED POTENTIALLY DETRIMENTAL OUTCOMES IN IMMUNE-MEDIATED AND CHRONIC INFLAMMATORY DISEASES. HERE WE DEFINE 'TRAINED IMMUNITY' AS A BIOLOGICAL PROCESS AND DISCUSS THE INNATE STIMULI AND THE EPIGENETIC AND METABOLIC REPROGRAMMING EVENTS THAT SHAPE THE INDUCTION OF TRAINED IMMUNITY. 2020 17 5322 31 PULMONARY DISEASES AND AGEING. CHRONIC OBSTRUCTIVE PULMONARY DISEASE (COPD) AND IDIOPATHIC PULMONARY FIBROSIS ARE REGARDED AS A DISEASES OF ACCELERATED LUNG AGEING AND SHOW ALL OF THE HALLMARKS OF AGEING, INCLUDING TELOMERE SHORTENING, CELLULAR SENESCENCE, ACTIVATION OF PI3 KINASE-MTOR SIGNALING, IMPAIRED AUTOPHAGY, MITOCHONDRIAL DYSFUNCTION, STEM CELL EXHAUSTION, EPIGENETIC CHANGES, ABNORMAL MICRORNA PROFILES, IMMUNOSENESCENCE AND A LOW GRADE CHRONIC INFLAMMATION DUE TO SENESCENCE-ASSOCIATED SECRETORY PHENOTYPE (SASP). MANY OF THESE AGEING MECHANISMS ARE DRIVEN BY EXOGENOUS AND ENDOGENOUS OXIDATIVE STRESS. THERE IS ALSO A REDUCTION IN ANTI-AGEING MOLECULES, SUCH AS SIRTUINS AND KLOTHO, WHICH FURTHER ACCELERATE THE AGEING PROCESS. UNDERSTANDING THESE MOLECULAR MECHANISMS HAS IDENTIFIED SEVERAL NOVEL THERAPEUTIC TARGETS AND SEVERAL DRUGS AND DIETARY INTERVENTIONS ARE NOW IN DEVELOPMENT TO TREAT CHRONIC LUNG DISEASE. 2019 18 4094 32 MATERNAL SIGNALS FOR PROGENY PREVENTION AGAINST ALLERGY AND ASTHMA. ALLERGY AND ASTHMA ARE CHRONIC INFLAMMATORY DISEASES WHICH RESULT FROM COMPLEX GENE-ENVIRONMENT INTERACTIONS. RECENT EVIDENCE INDICATES THE IMPORTANCE OF PRENATAL AND POSTNATAL DEVELOPMENTAL PROCESSES IN TERMS OF MATURATION OF BALANCED IMMUNE RESPONSES. ACCORDING TO THE CURRENT VIEW, GENE-ENVIRONMENT INTERACTIONS DURING A RESTRICTED TIME FRAME ARE RESPONSIBLE FOR PROGRAMMING OF THE IMMUNE SYSTEM IN FAVOR OF ALLERGIC IMMUNE MECHANISMS LATER IN LIFE. THE INTERACTION BETWEEN GENES AND ENVIRONMENT IS COMPLEX AND ONLY PARTIALLY UNDERSTOOD; HOWEVER, HERITABLE EPIGENETIC MODIFICATIONS INCLUDING CHEMICAL ADDITIONS IN AND ALTERNATIVE PACKAGING OF THE DNA HAVE BEEN SHOWN TO PLAY A CRUCIAL ROLE IN THIS CONTEXT. NOVEL DATA INDICATE THAT EPIGENETIC MECHANISMS CONTRIBUTE TO THE DEVELOPMENT OF T-HELPER CELL FUNCTION. ENVIRONMENTAL FACTORS, INCLUDING DIESEL EXHAUST PARTICLES (DEP), VITAMINS AND TOBACCO SMOKE, OPERATE THROUGH SUCH MECHANISMS. FURTHERMORE, THE ROLE OF ENVIRONMENTAL MICROBES PROVIDES ANOTHER AND MAYBE EVEN MORE IMPORTANT GROUP OF EXOGENOUS EXPOSURES WHICH OPERATES IN THIS CRITICAL TIME FRAME. 2011 19 4981 36 PATHOPHYSIOLOGY OF SYSTEMIC SCLEROSIS: CURRENT UNDERSTANDING AND NEW INSIGHTS. INTRODUCTION: SYSTEMIC SCLEROSIS (SSC) IS A COMPLEX AUTOIMMUNE CONNECTIVE TISSUE DISEASE CHARACTERIZED BY CHRONIC AND PROGRESSIVE TISSUE AND ORGAN FIBROSIS WITH BROAD PATIENT-TO-PATIENT VARIABILITY. SOME RISK FACTORS ARE KNOWN AND INCLUDE COMBINATION OF PERSISTENT RAYNAUD'S PHENOMENON, STEROID HORMONE IMBALANCE, SELECTED CHEMICALS, THERMAL, OR OTHER INJURIES. ENDOGENOUS AND/OR EXOGENOUS ENVIRONMENTAL TRIGGER/RISK FACTORS PROMOTE EPIGENETIC MECHANISMS IN GENETICALLY PRIMED SUBJECTS. DISEASE PATHOGENESIS PRESENTS EARLY MICROVASCULAR CHANGES WITH ENDOTHELIAL CELL DYSFUNCTION, FOLLOWED BY THE ACTIVATION OF MECHANISMS PROMOTING THEIR TRANSITION INTO MYOFIBROBLASTS. A COMPLEX AUTOIMMUNE RESPONSE, INVOLVING INNATE AND ADAPTIVE IMMUNITY WITH SPECIFIC/FUNCTIONAL AUTOANTIBODY PRODUCTION, CHARACTERIZES THE DISEASE. PROGRESSIVE FIBROSIS AND ISCHEMIA INVOLVE SKIN AND VISCERAL ORGANS RESULTING IN THEIR IRREVERSIBLE DAMAGE/FAILURE. PROGENITOR CIRCULATING CELLS (MONOCYTES, FIBROCYTES), TOGETHER WITH GROWTH FACTORS AND CYTOKINES PARTICIPATE IN DISEASE DIFFUSION AND EVOLUTION. EPIGENETIC, VASCULAR AND IMMUNOLOGIC MECHANISMS IMPLICATED IN SYSTEMIC FIBROSIS, REPRESENT MAJOR TARGETS FOR INCOMING DISEASE MODIFYING THERAPEUTIC APPROACHES. AREAS COVERED: THIS REVIEW DISCUSSES CURRENT UNDERSTANDING AND NEW INSIGHTS OF SSC PATHOGENESIS, THROUGH AN OVERVIEW OF THE MOST RELEVANT ADVANCEMENTS TO PRESENT ASPECTS AND MECHANISMS INVOLVED IN DISEASE PATHOGENESIS. EXPERT OPINION: CONSIDERING SSC INTRICACY/HETEROGENEITY, EARLY COMBINATION THERAPY WITH VASODILATORS, IMMUNOSUPPRESSIVE AND ANTIFIBROTIC DRUGS SHOULD SUCCESSFULLY DOWNREGULATE THE DISEASE PROGRESSION, ESPECIALLY IF STARTED FROM THE BEGINNING. 2019 20 6494 38 TRAINED IMMUNITY AS A NOVEL THERAPEUTIC STRATEGY. RECENT STUDIES HAVE SHOWN THAT UPON CERTAIN VACCINATIONS OR INFECTIONS HUMAN INNATE IMMUNE CELLS CAN UNDERGO EXTENSIVE METABOLIC AND EPIGENETIC REPROGRAMMING, WHICH RESULTS IN ENHANCED IMMUNE RESPONSES UPON HETEROLOGOUS RE-INFECTION, A PROCESS TERMED TRAINED IMMUNITY. TRAINED IMMUNITY HAS ALSO BEEN SHOWN TO BE INAPPROPRIATELY ACTIVATED IN INFLAMMATORY DISEASES. THIS PROVIDES THE POTENTIAL FOR IDENTIFYING NOVEL THERAPEUTIC TARGETS: POTENTIATION OF TRAINED IMMUNITY COULD PROTECT FROM SECONDARY INFECTIONS AND REVERSE IMMUNOTOLERANT STATES, WHILE INHIBITION OF TRAINED IMMUNITY MIGHT REDUCE EXCESSIVE IMMUNE ACTIVATION IN CHRONIC INFLAMMATORY CONDITIONS. BY TARGETING SPECIFIC MECHANISMS OF TRAINED IMMUNITY ON EITHER IMMUNOLOGIC, METABOLIC OR EPIGENETIC LEVEL, NOVEL THERAPEUTIC APPROACHES COULD BE DEVELOPED. 2018