1 2069 138 EPIGENETIC CONTROL OF SKELETAL MUSCLE REGENERATION: INTEGRATING GENETIC DETERMINANTS AND ENVIRONMENTAL CHANGES. DURING EMBRYONIC DEVELOPMENT, PLURIPOTENT CELLS ARE GENETICALLY COMMITTED TO SPECIFIC LINEAGES BY THE EXPRESSION OF CELL-TYPE-SPECIFIC TRANSCRIPTIONAL ACTIVATORS THAT DIRECT THE FORMATION OF SPECIALIZED TISSUES AND ORGANS IN RESPONSE TO DEVELOPMENTAL CUES. CHROMATIN-MODIFYING PROTEINS ARE EMERGING AS ESSENTIAL COMPONENTS OF THE EPIGENETIC MACHINERY, WHICH ESTABLISHES THE NUCLEAR LANDSCAPE THAT ULTIMATELY DETERMINES THE FINAL IDENTITY AND FUNCTIONAL SPECIALIZATION OF ADULT CELLS. RECENT EVIDENCE HAS REVEALED THAT DISCRETE POPULATIONS OF ADULT CELLS CAN RETAIN THE ABILITY TO ADOPT ALTERNATIVE CELL FATES IN RESPONSE TO ENVIRONMENTAL CUES. THESE CELLS INCLUDE CONVENTIONAL ADULT STEM CELLS AND A STILL POORLY DEFINED COLLECTION OF CELL TYPES ENDOWED WITH FACULTATIVE PHENOTYPE AND FUNCTIONAL PLASTICITY. UNDER PHYSIOLOGICAL CONDITIONS OR ADAPTIVE STATES, THESE CELLS COOPERATE TO SUPPORT TISSUE AND ORGAN HOMEOSTASIS, AND TO PROMOTE GROWTH OR COMPENSATORY REGENERATION. HOWEVER, DURING CHRONIC DISEASES AND AGING THESE CELLS CAN ADOPT A PATHOLOGICAL PHENOTYPE AND MEDIATE MALADAPTIVE RESPONSES, SUCH AS THE FORMATION OF FIBROTIC SCARS AND FAT DEPOSITION THAT PROGRESSIVELY REPLACES STRUCTURAL AND FUNCTIONAL UNITS OF TISSUES AND ORGANS. THE MOLECULAR DETERMINANTS OF THESE PHENOTYPIC TRANSITIONS ARE ONLY EMERGING FROM RECENT STUDIES THAT REVEAL HOW DYNAMIC CHROMATIN STATES CAN GENERATE FLEXIBLE EPIGENETIC LANDSCAPES, WHICH CONFER ON CELLS THE ABILITY TO RETAIN PARTIAL PLURIPOTENCY AND ADAPT TO ENVIRONMENTAL CHANGES. THIS REVIEW SUMMARIZES OUR CURRENT KNOWLEDGE ON THE ROLE OF THE EPIGENETIC MACHINERY AS A 'FILTER' BETWEEN GENETIC COMMITMENT AND ENVIRONMENTAL SIGNALS IN CELL TYPES THAT CAN ALTERNATIVELY PROMOTE SKELETAL MUSCLE REGENERATION OR FIBRO-ADIPOGENIC DEGENERATION. 2013 2 2342 30 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 3 5631 45 SENESCENCE-INFLAMMATORY REGULATION OF REPARATIVE CELLULAR REPROGRAMMING IN AGING AND CANCER. THE INABILITY OF ADULT TISSUES TO TRANSITORILY GENERATE CELLS WITH FUNCTIONAL STEM CELL-LIKE PROPERTIES IS A MAJOR OBSTACLE TO TISSUE SELF-REPAIR. NUCLEAR REPROGRAMMING-LIKE PHENOMENA THAT INDUCE A TRANSIENT ACQUISITION OF EPIGENETIC PLASTICITY AND PHENOTYPE MALLEABILITY MAY CONSTITUTE A REPARATIVE ROUTE THROUGH WHICH HUMAN TISSUES RESPOND TO INJURY, STRESS, AND DISEASE. HOWEVER, TISSUE REJUVENATION SHOULD INVOLVE NOT ONLY THE TRANSIENT EPIGENETIC REPROGRAMMING OF DIFFERENTIATED CELLS, BUT ALSO THE COMMITTED RE-ACQUISITION OF THE ORIGINAL OR ALTERNATIVE COMMITTED CELL FATE. CHRONIC OR UNRESTRAINED EPIGENETIC PLASTICITY WOULD DRIVE AGING PHENOTYPES BY IMPAIRING THE REPAIR OR THE REPLACEMENT OF DAMAGED CELLS; SUCH UNCONTROLLED PHENOMENA OF IN VIVO REPROGRAMMING MIGHT ALSO GENERATE CANCER-LIKE CELLULAR STATES. WE HEREIN PROPOSE THAT THE ABILITY OF SENESCENCE-ASSOCIATED INFLAMMATORY SIGNALING TO REGULATE IN VIVO REPROGRAMMING CYCLES OF TISSUE REPAIR OUTLINES A THRESHOLD MODEL OF AGING AND CANCER. THE DEGREE OF SENESCENCE/INFLAMMATION-ASSOCIATED DEVIATION FROM THE HOMEOSTATIC STATE MAY DELINEATE A TYPE OF THRESHOLDING ALGORITHM DISTINGUISHING BENEFICIAL FROM DELETERIOUS EFFECTS OF IN VIVO REPROGRAMMING. FIRST, TRANSIENT ACTIVATION OF NF-KAPPAB-RELATED INNATE IMMUNITY AND SENESCENCE-ASSOCIATED INFLAMMATORY COMPONENTS (E.G., IL-6) MIGHT FACILITATE REPARATIVE CELLULAR REPROGRAMMING IN RESPONSE TO ACUTE INFLAMMATORY EVENTS. SECOND, PARA-INFLAMMATION SWITCHES MIGHT PROMOTE LONG-LASTING BUT REVERSIBLE REFRACTORINESS TO REPARATIVE CELLULAR REPROGRAMMING. THIRD, CHRONIC SENESCENCE-ASSOCIATED INFLAMMATORY SIGNALING MIGHT LOCK CELLS IN HIGHLY PLASTIC EPIGENETIC STATES DISABLED FOR REPARATIVE DIFFERENTIATION. THE CONSIDERATION OF A CELLULAR REPROGRAMMING-CENTERED VIEW OF EPIGENETIC PLASTICITY AS A FUNDAMENTAL ELEMENT OF A TISSUE'S CAPACITY TO UNDERGO SUCCESSFUL REPAIR, AGING DEGENERATION OR MALIGNANT TRANSFORMATION SHOULD PROVIDE CHALLENGING STOCHASTIC INSIGHTS INTO THE CURRENT DETERMINISTIC GENETIC PARADIGM FOR MOST CHRONIC DISEASES, THEREBY INCREASING THE SPECTRUM OF THERAPEUTIC APPROACHES FOR PHYSIOLOGICAL AGING AND CANCER. 2017 4 2812 32 FIBROBLAST MEMORY IN DEVELOPMENT, HOMEOSTASIS AND DISEASE. FIBROBLASTS ARE THE MAJOR CELL POPULATION IN THE CONNECTIVE TISSUE OF MOST ORGANS, WHERE THEY ARE ESSENTIAL FOR THEIR STRUCTURAL INTEGRITY. THEY ARE BEST KNOWN FOR THEIR ROLE IN REMODELLING THE EXTRACELLULAR MATRIX, HOWEVER MORE RECENTLY THEY HAVE BEEN RECOGNISED AS A FUNCTIONALLY HIGHLY DIVERSE CELL POPULATION THAT CONSTANTLY RESPONDS AND ADAPTS TO THEIR ENVIRONMENT. BIOLOGICAL MEMORY IS THE PROCESS OF A SUSTAINED ALTERED CELLULAR STATE AND FUNCTIONS IN RESPONSE TO A TRANSIENT OR PERSISTENT ENVIRONMENTAL STIMULUS. WHILE IT IS WELL ESTABLISHED THAT FIBROBLASTS RETAIN A MEMORY OF THEIR ANATOMICAL LOCATION, HOW OTHER ENVIRONMENTAL STIMULI INFLUENCE FIBROBLAST BEHAVIOUR AND FUNCTION IS LESS CLEAR. THE ABILITY OF FIBROBLASTS TO RESPOND AND MEMORISE DIFFERENT ENVIRONMENTAL STIMULI IS ESSENTIAL FOR TISSUE DEVELOPMENT AND HOMEOSTASIS AND MAY BECOME DYSREGULATED IN CHRONIC DISEASE CONDITIONS SUCH AS FIBROSIS AND CANCER. HERE WE SUMMARISE THE FOUR EMERGING KEY AREAS OF FIBROBLAST ADAPTATION: POSITIONAL, MECHANICAL, INFLAMMATORY, AND METABOLIC MEMORY AND HIGHLIGHT THE UNDERLYING MECHANISMS AND THEIR IMPLICATIONS IN TISSUE HOMEOSTASIS AND DISEASE. 2021 5 5202 36 PRENATAL ORIGINS OF ADULT DISEASE. PURPOSE OF REVIEW: HUMAN EPIDEMIOLOGICAL AND ANIMAL STUDIES SHOW THAT MANY CHRONIC ADULT CONDITIONS HAVE THEIR ANTECEDENTS IN COMPROMISED FETAL AND EARLY POSTNATAL DEVELOPMENT. DEVELOPMENTAL PROGRAMMING IS DEFINED AS THE RESPONSE BY THE DEVELOPING MAMMALIAN ORGANISM TO A SPECIFIC CHALLENGE DURING A CRITICAL TIME WINDOW THAT ALTERS THE TRAJECTORY OF DEVELOPMENT WITH RESULTING PERSISTENT EFFECTS ON PHENOTYPE. MAMMALS PASS MORE BIOLOGICAL MILESTONES BEFORE BIRTH THAN ANY OTHER TIME IN THEIR LIVES. EACH INDIVIDUAL'S PHENOTYPE IS INFLUENCED BY THE DEVELOPMENTAL ENVIRONMENT AS MUCH AS THEIR GENES. A BETTER UNDERSTANDING IS REQUIRED OF GENE-ENVIRONMENT INTERACTIONS LEADING TO ADULT DISEASE. RECENT FINDINGS: DURING DEVELOPMENT, THERE ARE CRITICAL PERIODS OF VULNERABILITY TO SUBOPTIMAL CONDITIONS WHEN PROGRAMMING MAY PERMANENTLY MODIFY DISEASE SUSCEPTIBILITY. PROGRAMMING INVOLVES STRUCTURAL CHANGES IN IMPORTANT ORGANS; ALTERED CELL NUMBER, IMBALANCE IN DISTRIBUTION OF DIFFERENT CELL TYPES WITHIN THE ORGAN, AND ALTERED BLOOD SUPPLY OR RECEPTOR NUMBERS. COMPENSATORY EFFORTS BY THE FETUS MAY CARRY A PRICE. EFFECTS OF PROGRAMMING MAY PASS ACROSS GENERATIONS BY MECHANISMS THAT DO NOT NECESSARILY INVOLVE STRUCTURAL GENE CHANGES. PROGRAMMING OFTEN HAS DIFFERENT EFFECTS IN MALES AND FEMALES. SUMMARY: DEVELOPMENTAL PROGRAMMING SHOWS THAT EPIGENETIC FACTORS PLAY MAJOR ROLES IN DEVELOPMENT OF PHENOTYPE AND PREDISPOSITION TO DISEASE IN LATER LIFE. 2008 6 6054 37 THE CURRENT STATE AND FUTURE OF T-CELL EXHAUSTION RESEARCH. 'EXHAUSTION' IS A TERM USED TO DESCRIBE A STATE OF NATIVE AND REDIRECTED T-CELL HYPO-RESPONSIVENESS RESULTING FROM PERSISTENT ANTIGEN EXPOSURE DURING CHRONIC VIRAL INFECTIONS OR CANCER. ALTHOUGH A WELL-ESTABLISHED PHENOTYPE ACROSS MICE AND HUMANS, EXHAUSTION AT THE MOLECULAR LEVEL REMAINS POORLY DEFINED AND INCONSISTENT ACROSS THE LITERATURE. THIS IS, IN PART, DUE TO AN OVERRELIANCE ON SURFACE RECEPTORS TO DEFINE THESE CELLS AND EXPLAIN EXHAUSTIVE BEHAVIOURS, AN INCOMPLETE UNDERSTANDING OF HOW EXHAUSTION ARISES, AND A LACK OF CLARITY OVER WHETHER EXHAUSTION IS THE SAME ACROSS CONTEXTS, E.G. CHRONIC VIRAL INFECTIONS VERSUS CANCER. WITH THE DEVELOPMENT OF SYSTEMS-BASED GENETIC APPROACHES SUCH AS SINGLE-CELL RNA-SEQ AND CRISPR SCREENS APPLIED TO IN VIVO DATA, WE ARE MOVING CLOSER TO A CONSENSUS VIEW OF EXHAUSTION, ALTHOUGH UNDERSTANDING HOW IT ARISES REMAINS CHALLENGING GIVEN THE DIFFICULTY IN MANIPULATING THE IN VIVO SETTING. ACCORDINGLY, PRODUCING AND STUDYING EXHAUSTED T-CELLS EX VIVO ARE BURGEONING, ALLOWING EXPERIMENTS TO BE CONDUCTED AT SCALE UP AND WITH HIGH THROUGHPUT. HERE, WE FIRST REVIEW WHAT IS CURRENTLY KNOWN ABOUT T-CELL EXHAUSTION AND HOW IT'S BEING STUDIED. WE THEN DISCUSS HOW IMPROVEMENTS IN THEIR METHOD OF ISOLATION/PRODUCTION AND EXAMINING THE IMPACT OF DIFFERENT MICROENVIRONMENTAL SIGNALS AND CELL INTERACTIONS HAVE NOW BECOME AN ACTIVE AREA OF RESEARCH. FINALLY, WE DISCUSS WHAT THE FUTURE HOLDS FOR THE ANALYSIS OF THIS PHYSIOLOGICAL CONDITION AND, GIVEN THE DIVERSITY OF WAYS IN WHICH EXHAUSTED CELLS ARE NOW BEING GENERATED, PROPOSE THE ADOPTION OF A UNIFIED APPROACH TO CLEARLY DEFINING EXHAUSTION USING A SET OF METABOLIC-, EPIGENETIC-, TRANSCRIPTIONAL-, AND ACTIVATION-BASED PHENOTYPIC MARKERS, THAT WE CALL 'M.E.T.A'. 2023 7 2184 36 EPIGENETIC MECHANISMS THAT UNDERPIN METABOLIC AND CARDIOVASCULAR DISEASES. CELLULAR COMMITMENT TO A SPECIFIC LINEAGE IS CONTROLLED BY DIFFERENTIAL SILENCING OF GENES, WHICH IN TURN DEPENDS ON EPIGENETIC PROCESSES SUCH AS DNA METHYLATION AND HISTONE MODIFICATION. DURING EARLY EMBRYOGENESIS, THE MAMMALIAN GENOME IS 'WIPED CLEAN' OF MOST EPIGENETIC MODIFICATIONS, WHICH ARE PROGRESSIVELY RE-ESTABLISHED DURING EMBRYONIC DEVELOPMENT. THUS, THE EPIGENOME OF EACH MATURE CELLULAR LINEAGE CARRIES THE RECORD OF ITS DEVELOPMENTAL HISTORY. THE SUBSEQUENT TRAJECTORY AND PATTERN OF DEVELOPMENT ARE ALSO RESPONSIVE TO ENVIRONMENTAL INFLUENCES, AND SUCH PLASTICITY IS LIKELY TO HAVE AN EPIGENETIC BASIS. EPIGENETIC MARKS MAY BE TRANSMITTED ACROSS GENERATIONS, EITHER DIRECTLY BY PERSISTING THROUGH MEIOSIS OR INDIRECTLY THROUGH REPLICATION IN THE NEXT GENERATION OF THE CONDITIONS IN WHICH THE EPIGENETIC CHANGE OCCURRED. DEVELOPMENTAL PLASTICITY EVOLVED TO MATCH AN ORGANISM TO ITS ENVIRONMENT, AND A MISMATCH BETWEEN THE PHENOTYPIC OUTCOME OF ADAPTIVE PLASTICITY AND THE CURRENT ENVIRONMENT INCREASES THE RISK OF METABOLIC AND CARDIOVASCULAR DISEASE. THESE CONSIDERATIONS POINT TO EPIGENETIC PROCESSES AS A KEY MECHANISM THAT UNDERPINS THE DEVELOPMENTAL ORIGINS OF CHRONIC NONCOMMUNICABLE DISEASE. HERE, WE REVIEW THE EVIDENCE THAT ENVIRONMENTAL INFLUENCES DURING MAMMALIAN DEVELOPMENT LEAD TO STABLE CHANGES IN THE EPIGENOME THAT ALTER THE INDIVIDUAL'S SUSCEPTIBILITY TO CHRONIC METABOLIC AND CARDIOVASCULAR DISEASE, AND DISCUSS THE CLINICAL IMPLICATIONS. 2009 8 1482 37 DIVERSITY, MECHANISMS, AND SIGNIFICANCE OF MACROPHAGE PLASTICITY. MACROPHAGES ARE A DIVERSE SET OF CELLS PRESENT IN ALL BODY COMPARTMENTS. THIS DIVERSITY IS IMPRINTED BY THEIR ONTOGENETIC ORIGIN (EMBRYONAL VERSUS ADULT BONE MARROW-DERIVED CELLS); THE ORGAN CONTEXT; BY THEIR ACTIVATION OR DEACTIVATION BY VARIOUS SIGNALS IN THE CONTEXTS OF MICROBIAL INVASION, TISSUE DAMAGE, AND METABOLIC DERANGEMENT; AND BY POLARIZATION OF ADAPTIVE T CELL RESPONSES. CLASSIC ADAPTIVE RESPONSES OF MACROPHAGES INCLUDE TOLERANCE, PRIMING, AND A WIDE SPECTRUM OF ACTIVATION STATES, INCLUDING M1, M2, OR M2-LIKE. MOREOVER, MACROPHAGES CAN RETAIN LONG-TERM IMPRINTING OF MICROBIAL ENCOUNTERS (TRAINED INNATE IMMUNITY). SINGLE-CELL ANALYSIS OF MONONUCLEAR PHAGOCYTES IN HEALTH AND DISEASE HAS ADDED A NEW DIMENSION TO OUR UNDERSTANDING OF THE DIVERSITY OF MACROPHAGE DIFFERENTIATION AND ACTIVATION. EPIGENETIC LANDSCAPES, TRANSCRIPTION FACTORS, AND MICRORNA NETWORKS UNDERLIE THE ADAPTABILITY OF MACROPHAGES TO DIFFERENT ENVIRONMENTAL CUES. MACROPHAGE PLASTICITY, AN ESSENTIAL COMPONENT OF CHRONIC INFLAMMATION, AND ITS INVOLVEMENT IN DIVERSE HUMAN DISEASES, MOST NOTABLY CANCER, IS DISCUSSED HERE AS A PARADIGM. 2020 9 3706 36 INFLUENCE OF GENETICS ON DISEASE SUSCEPTIBILITY AND PROGRESSION. FOR MANY CHRONIC DISEASES, THE INFLUENCE OF GENETICS IS COMPLEX AND PHENOTYPES DO NOT CONFORM TO SIMPLE MENDELIAN PATTERNS OF INHERITANCE. DISCUSSED HERE ARE TWO TYPES OF GENETIC INFLUENCES ON HEALTHY AGING. THE FIRST INVOLVES VARIATION IN THE GENE SEQUENCE ITSELF AND HOW THIS MAY INFLUENCE DISEASE SUSCEPTIBILITY, PROGRESSION, AND SEVERITY, INTERACTING WITH OTHER RECOGNIZED RISK FACTORS. THE SECOND INVOLVES EPIGENETIC REGULATORY MECHANISMS THAT MAY POTENTIALLY PROVIDE INSIGHT INTO HOW ENVIRONMENTAL INFLUENCES AFFECT THE EXPRESSED GENOME, THUS IMPROVING OUR UNDERSTANDING OF THE GENETIC MECHANISMS UNDERLYING MULTIFACTORIAL DISEASES. THE INTERLEUKIN-1 FAMILY OF CYTOKINES CAN BE USED TO ILLUSTRATE HOW GENETIC SEQUENCE VARIATION MAY AFFECT SUCH DISEASES. THIS CYTOKINE FAMILY PLAYS A KEY ROLE IN MEDIATING INFLAMMATION, WHICH IS NOW UNDERSTOOD TO BE A CENTRAL COMPONENT OF A GROWING NUMBER OF CHRONIC DISEASES. RECENT WORK HAS REVEALED MANY SEQUENCE VARIATIONS IN THE REGULATORY DNA OF GENES ENCODING IMPORTANT MEMBERS OF THE INTERLEUKIN-1 FAMILY, AND THESE VARIATIONS ARE ASSOCIATED WITH DIFFERENTIAL EFFECTS ON THE INFLAMMATORY RESPONSE. THE INTERACTIONS OF ENVIRONMENTAL FACTORS WITH BOTH DNA SEQUENCE VARIATIONS AND EPIGENETIC MODIFICATIONS ARE LIKELY TO DETERMINE THE PHENOTYPES OF MULTIFACTORIAL DISEASES OF AGING AS WELL AS THE PHENOTYPE OF HEALTHY AGING. 2007 10 229 38 ADAPTATION OR PATHOLOGY? THE ROLE OF PRENATAL STRESSOR TYPE AND INTENSITY IN THE DEVELOPMENTAL PROGRAMING OF ADULT PHENOTYPE. THE MOTHER IS THE MAJOR INTERFACE BETWEEN THE OFFSPRING AND ITS PRENATAL ENVIRONMENT. PRENATAL TOXINS AND STRESS-INDUCING PHYSICAL AGENTS ARE IMPORTANT FACTORS PROGRAMMING THE DEVELOPMENTAL TRAJECTORY OF MAMMALS THAT LIKELY INVOLVE EPIGENETIC MODIFICATIONS. HOWEVER, PRENATAL STRESSORS COMMONLY-USED IN THE LABORATORY (E.G. PRENATAL RESTRAINT STRESS AND PRENATAL CHRONIC VARIABLE STRESS) ARE TYPICALLY ADMINISTERED AT HIGH INTENSITIES. THESE EXPOSURES TYPICALLY LEAD TO PATHOLOGICAL PHENOTYPES SUPPORTING THE DEVELOPMENT ORIGIN OF HEALTH AND DISEASE HYPOTHESIS. IN THIS REVIEW, WE COMPARE THE PHENOTYPIC OUTCOMES OF THESE COMMONLY-USED PRENATAL STRESSORS TO AN ECOLOGICALLY-RELEVANT, PSYCHOGENIC STRESSOR THAT HAS BEEN PRESENT OVER EVOLUTIONARY TIMES, PREDATOR OR PREDATOR CUES PRESENCE. PRENATAL STRESS BY PREDATOR THREAT RESULTS IN BEHAVIORAL, PHYSIOLOGICAL, ENDOCRINE, TRANSCRIPT ABUNDANCE AND EPIGENETIC (DNA METHYLATION) MODIFICATIONS. THESE PHENOTYPIC MODIFICATIONS ARE CONSISTENT WITH DEVELOPMENTAL FORECASTING ACCORDING TO THE PREDICTIVE ADAPTIVE RESPONSE HYPOTHESIS, YIELDING ADAPTIVE RESPONSES IN ENVIRONMENTS WHERE SUCH PREDATION STRESS IS PRESENT. THE EVIDENCE DESCRIBED IN THIS REVIEW SUGGESTS THAT THE TYPE OF PRENATAL STRESS AGENT AND ITS INTENSITY MODIFIES THE PHENOTYPE EXPRESSED, WHICH CAN RANGE FROM ADAPTIVE TO PATHOLOGICAL. PRENATAL BISPHENOL A EXPOSURE STUDIES ARE PRESENTED AS AN EXAMPLE WHERE GRADED INTENSITIES (CONCENTRATIONS) OF PRENATAL TOXIN EXPOSURE CAN BE COMPARED DIRECTLY. FINALLY, WE EMPHASIZE THE IMPORTANCE OF STUDYING BOTH SEXES IN THESE STUDIES, AS SEX DIFFERENCES APPEAR TO BE A COMMON FEATURE OF THE RESPONSE TO PRENATAL STRESS. 2018 11 1748 36 EARLY LIFE EVENTS AND THEIR CONSEQUENCES FOR LATER DISEASE: A LIFE HISTORY AND EVOLUTIONARY PERSPECTIVE. BIOMEDICAL SCIENCE HAS LITTLE CONSIDERED THE RELEVANCE OF LIFE HISTORY THEORY AND EVOLUTIONARY AND ECOLOGICAL DEVELOPMENTAL BIOLOGY TO CLINICAL MEDICINE. HOWEVER, THE OBSERVATIONS THAT EARLY LIFE INFLUENCES CAN ALTER LATER DISEASE RISK--THE "DEVELOPMENTAL ORIGINS OF HEALTH AND DISEASE" (DOHAD) PARADIGM--HAVE LED TO A RECOGNITION THAT THESE PERSPECTIVES CAN INFORM OUR UNDERSTANDING OF HUMAN BIOLOGY. WE PROPOSE THAT THE DOHAD PHENOMENON CAN BE CONSIDERED AS A SUBSET OF THE BROADER PROCESSES OF DEVELOPMENTAL PLASTICITY BY WHICH ORGANISMS ADAPT TO THEIR ENVIRONMENT DURING THEIR LIFE COURSE. SUCH ADAPTIVE PROCESSES ALLOW GENOTYPIC VARIATION TO BE PRESERVED THROUGH TRANSIENT ENVIRONMENTAL CHANGES. CUES FOR PLASTICITY OPERATE PARTICULARLY DURING EARLY DEVELOPMENT; THEY MAY AFFECT A SINGLE ORGAN OR SYSTEM, BUT GENERALLY THEY INDUCE INTEGRATED ADJUSTMENTS IN THE MATURE PHENOTYPE, A PROCESS UNDERPINNED BY EPIGENETIC MECHANISMS AND INFLUENCED BY PREDICTION OF THE MATURE ENVIRONMENT. IN MAMMALS, AN ADVERSE INTRAUTERINE ENVIRONMENT RESULTS IN AN INTEGRATED SUITE OF RESPONSES, SUGGESTING THE INVOLVEMENT OF A FEW KEY REGULATORY GENES, THAT RESETS THE DEVELOPMENTAL TRAJECTORY IN EXPECTATION OF POOR POSTNATAL CONDITIONS. MISMATCH BETWEEN THE ANTICIPATED AND THE ACTUAL MATURE ENVIRONMENT EXPOSES THE ORGANISM TO RISK OF ADVERSE CONSEQUENCES-THE GREATER THE MISMATCH, THE GREATER THE RISK. FOR HUMANS, PREDICTION IS INACCURATE FOR MANY INDIVIDUALS BECAUSE OF CHANGES IN THE POSTNATAL ENVIRONMENT TOWARD ENERGY-DENSE NUTRITION AND LOW ENERGY EXPENDITURE, CONTRIBUTING TO THE EPIDEMIC OF CHRONIC NONCOMMUNICABLE DISEASE. THIS VIEW OF HUMAN DISEASE FROM THE PERSPECTIVES OF LIFE HISTORY BIOLOGY AND EVOLUTIONARY THEORY OFFERS NEW APPROACHES TO PREVENTION, DIAGNOSIS AND INTERVENTION. 2007 12 357 33 ALTERNATIVE MODELS FOR TRANSGENERATIONAL EPIGENETIC INHERITANCE: MOLECULAR PSYCHIATRY BEYOND MICE AND MAN. MENTAL ILLNESS REMAINS THE GREATEST CHRONIC HEALTH BURDEN GLOBALLY WITH FEW IN-ROADS HAVING BEEN MADE DESPITE SIGNIFICANT ADVANCES IN GENOMIC KNOWLEDGE IN RECENT DECADES. THE FIELD OF PSYCHIATRY IS CONSTANTLY CHALLENGED TO BRING NEW APPROACHES AND TOOLS TO ADDRESS AND TREAT THE NEEDS OF VULNERABLE INDIVIDUALS AND SUBPOPULATIONS, AND THAT HAS TO BE SUPPORTED BY A CONTINUOUS GROWTH IN KNOWLEDGE. THE MAJORITY OF NEUROPSYCHIATRIC SYMPTOMS REFLECT COMPLEX GENE-ENVIRONMENT INTERACTIONS, WITH EPIGENETICS BRIDGING THE GAP BETWEEN GENETIC SUSCEPTIBILITY AND ENVIRONMENTAL STRESSORS THAT TRIGGER DISEASE ONSET AND DRIVE THE ADVANCEMENT OF SYMPTOMS. IT HAS MORE RECENTLY BEEN DEMONSTRATED IN PRECLINICAL MODELS THAT EPIGENETICS UNDERPINS THE TRANSGENERATIONAL INHERITANCE OF STRESS-RELATED BEHAVIOURAL PHENOTYPES IN BOTH PATERNAL AND MATERNAL LINEAGES, PROVIDING FURTHER SUPPORTING EVIDENCE FOR HERITABILITY IN HUMANS. HOWEVER, UNBIASED PROSPECTIVE STUDIES OF THIS NATURE ARE PRACTICALLY IMPOSSIBLE TO CONDUCT IN HUMANS SO PRECLINICAL MODELS REMAIN OUR BEST OPTION FOR RESEARCHING THE MOLECULAR PATHOPHYSIOLOGIES UNDERLYING MANY NEUROPSYCHIATRIC CONDITIONS. WHILE RODENTS WILL REMAIN THE DOMINANT MODEL SYSTEM FOR PRECLINICAL STUDIES (ESPECIALLY FOR ADDRESSING COMPLEX BEHAVIOURAL PHENOTYPES), THERE IS SCOPE TO EXPAND CURRENT RESEARCH OF THE MOLECULAR AND EPIGENETIC PATHOLOGIES BY USING INVERTEBRATE MODELS. HERE, WE WILL DISCUSS THE UTILITY AND ADVANTAGES OF TWO ALTERNATIVE MODEL ORGANISMS-CAENORHABDITIS ELEGANS AND DROSOPHILA MELANOGASTER-AND SUMMARISE THE COMPELLING INSIGHTS OF THE EPIGENETIC REGULATION OF TRANSGENERATIONAL INHERITANCE THAT ARE POTENTIALLY RELEVANT TO HUMAN PSYCHIATRY. 2021 13 6251 37 THE MICROBIOLOGICAL MEMORY, AN EPIGENETIC REGULATOR GOVERNING THE BALANCE BETWEEN GOOD HEALTH AND METABOLIC DISORDERS. IF THE TRANSMISSION OF BIOLOGICAL INFORMATION FROM ONE GENERATION TO THE NEXT IS BASED ON DNA, MOST HERITABLE PHENOTYPIC TRAITS SUCH AS CHRONIC METABOLIC DISEASES, ARE NOT LINKED TO GENETIC VARIATION IN DNA SEQUENCES. NON-GENETIC HERITABILITY MIGHT HAVE SEVERAL CAUSES INCLUDING EPIGENETIC, PARENTAL EFFECT, ADAPTIVE SOCIAL LEARNING, AND INFLUENCE OF THE ECOLOGICAL ENVIRONMENT. DISTINGUISHING AMONG THESE CAUSES IS CRUCIAL TO RESOLVE MAJOR PHENOTYPIC ENIGMAS. STRONG EVIDENCE INDICATES THAT CHANGES IN DNA EXPRESSION THROUGH VARIOUS EPIGENETIC MECHANISMS CAN BE LINKED TO PARENT-OFFSPRING RESEMBLANCE IN TERMS OF SENSITIVITY TO METABOLIC DISEASES. AMONG NON-GENETIC HERITABLE TRAITS, EARLY NUTRITION COULD ACCOUNT FOR A LONG TERM DEVIANT PROGRAMMING OF GENES EXPRESSION RESPONSIBLE FOR METABOLIC DISEASES IN ADULTHOOD. NUTRITION COULD SHAPE AN INADEQUATE GUT MICROBIOTA (DYSBIOSIS), TRIGGERING EPIGENETIC DEREGULATION OF TRANSCRIPTION WHICH CAN BE OBSERVED IN CHRONIC METABOLIC DISEASES. WE REVIEW HEREIN THE EVIDENCE THAT DYSBIOSIS MIGHT BE A MAJOR CAUSE OF HERITABLE EPIGENETIC PATTERNS FOUND TO BE ASSOCIATED WITH METABOLIC DISEASES. BY TAKING INTO ACCOUNT THE RECENT ADVANCES ON THE GUT MICROBIOME, WE HAVE AGGREGATED TOGETHER DIFFERENT OBSERVATIONS SUPPORTING THE HYPOTHESIS THAT THE GUT MICROBIOTA COULD PROMOTE THE MOLECULAR CROSSTALK BETWEEN BACTERIA AND SURROUNDING HOST CELLS WHICH CONTROLS THE PATHOLOGICAL EPIGENETIC SIGNATURE. WE INTRODUCE FOR THE FIRST TIME THE CONCEPT OF "MICROBIOLOGICAL MEMORY" AS THE MAIN REGULATOR OF THE EPIGENETIC SIGNATURES, THEREBY INDICATING THAT DIFFERENT CAUSES OF NON-GENETIC HERITABILITY CAN INTERACT IN COMPLEX PATHWAYS TO PRODUCE INHERITANCE. 2018 14 2644 33 EPIGENOMIC DRIVERS OF IMMUNE DYSFUNCTION IN AGING. AGING INEVITABLY LEADS TO REDUCED IMMUNE FUNCTION, LEAVING THE ELDERLY MORE SUSCEPTIBLE TO INFECTIONS, LESS ABLE TO RESPOND TO PATHOGEN CHALLENGES, AND LESS RESPONSIVE TO PREVENTATIVE VACCINATIONS. NO CELL TYPE IS EXEMPT FROM THE RAVAGES OF AGE, AND EXTENSIVE STUDIES HAVE FOUND AGE-RELATED ALTERATIONS IN THE FREQUENCIES AND FUNCTIONS OF BOTH STEM AND PROGENITOR CELLS, AS WELL AS EFFECTOR CELLS OF BOTH THE INNATE AND ADAPTIVE IMMUNE SYSTEMS. THE INTRINSIC FUNCTIONAL REDUCTION IN IMMUNE COMPETENCE IS ALSO ASSOCIATED WITH LOW-GRADE CHRONIC INFLAMMATION, TERMED "INFLAMM-AGING," WHICH FURTHER PERPETUATES IMMUNE DYSFUNCTION. WHILE MANY OF THESE AGE-RELATED CELLULAR CHANGES ARE WELL CHARACTERIZED, UNDERSTANDING THE MOLECULAR CHANGES THAT UNDERPIN THE FUNCTIONAL DECLINE HAS PROVEN MORE DIFFICULT. CHANGES IN CHROMATIN ARE INCREASINGLY APPRECIATED AS A CAUSATIVE MECHANISM OF CELLULAR AND ORGANISMAL AGING ACROSS SPECIES. THESE CHANGES INCLUDE INCREASED GENOMIC INSTABILITY THROUGH LOSS OF HETEROCHROMATIN AND INCREASED DNA DAMAGE, TELOMERE ATTRITION, AND EPIGENETIC ALTERATIONS. IN THIS REVIEW, WE DISCUSS THE CONNECTIONS BETWEEN CHROMATIN, IMMUNOCOMPETENCE, AND THE LOSS OF FUNCTION ASSOCIATED WITH MAMMALIAN IMMUNE AGING. THROUGH UNDERSTANDING THE MOLECULAR EVENTS WHICH UNDERPIN THE PHENOTYPIC CHANGES OBSERVED IN THE AGED IMMUNE SYSTEM, IT IS HOPED THAT THE AGED IMMUNE SYSTEM CAN BE RESTORED TO PROVIDE YOUTHFUL IMMUNITY ONCE MORE. 2019 15 2916 30 GENE VARIANTS AS DETERMINANTS OF LONGEVITY: FOCUS ON THE INFLAMMATORY FACTORS. HUMAN LONGEVITY IS AN EXTREMELY COMPLEX TRAIT WITH VARIOUS GENETIC, EPIGENETIC AND ENVIRONMENTAL FACTORS ACTING UPON THE LONGEVITY PHENOTYPE. IT IS NOW BECOMING EVIDENT THAT WHILST THE GENETIC DIFFERENCES CONTRIBUTE ONLY MODESTLY TO LIFE EXPECTANCY BEFORE THE AGE OF 60 YEARS, THEIR IMPACT ON SURVIVAL BECOMES MORE PROMINENT AT THE EXTREME AGES. SEVERAL LONGEVITY GENE CANDIDATES HAVE EMERGED DURING THE PAST DECADE; THE MAJORITY OF THEM ARE RELATED EITHER TO INFLAMMATORY FUNCTIONS, STRESS RESPONSE OR TO LIPID AND GLUCOSE METABOLISM. THE VARIANTS OF INFLAMMATORY AND IMMUNE RESPONSE GENES ARE OF SPECIAL INTEREST SINCE ADVANCING AGES IS ACCOMPANIED BY A DECLINE IN SEVERAL IMMUNE FUNCTIONS--A PHENOMENON CALLED IMMUNOSENESCENCE. PARADOXICALLY, AGEING IS ALSO CHARACTERISED BY CHRONIC LOW-GRADE INFLAMMATION TERMED "INFLAMMAGING", WHICH MANIFESTS AS A TWO- TO FOURFOLD INCREASE IN THE PRODUCTION OF PROINFLAMMATORY CYTOKINES AND ACUTE PHASE PROTEINS. THESE CONTRASTING PHENOMENA PROVIDE A FUNCTIONAL RATIONALE OF HOW THE GENETIC DIFFERENCES IN INFLAMMATORY MEDIATORS MAY MODIFY THE LIFE SPAN OF THE ELDERLY. BESIDES DESCRIBING THE PRE-EXISTING INFLAMMATORY AND IMMUNE-RELATED LONGEVITY GENE VARIANTS, IN THIS REVIEW, WE ALSO EXPLAIN SOME OF THE THEORETICAL AND PRACTICAL CHALLENGES THAT GENETIC LONGEVITY STUDIES OFTEN ENCOUNTER. 2010 16 6501 21 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 17 2525 35 EPIGENETICS AND TRAINED IMMUNITY. SIGNIFICANCE: A GROWING BODY OF CLINICAL AND EXPERIMENTAL EVIDENCE HAS CHALLENGED THE TRADITIONAL UNDERSTANDING THAT ONLY THE ADAPTIVE IMMUNE SYSTEM CAN MOUNT IMMUNOLOGICAL MEMORY. RECENT FINDINGS DESCRIBE THE ADAPTIVE CHARACTERISTICS OF THE INNATE IMMUNE SYSTEM, UNDERSCORED BY ITS ABILITY TO REMEMBER ANTECEDENT FOREIGN ENCOUNTERS AND RESPOND IN A NONSPECIFIC SENSITIZED MANNER TO REINFECTION. THIS HAS BEEN TERMED TRAINED INNATE IMMUNITY. ALTHOUGH BENEFICIAL IN THE CONTEXT OF RECURRENT INFECTIONS, THIS MIGHT ACTUALLY CONTRIBUTE TO CHRONIC IMMUNE-MEDIATED DISEASES, SUCH AS ATHEROSCLEROSIS. RECENT ADVANCES: IN LINE WITH ITS PROPOSED ROLE IN SUSTAINING CELLULAR MEMORIES, EPIGENETIC REPROGRAMMING HAS EMERGED AS A CRITICAL DETERMINANT OF TRAINED IMMUNITY. RECENT TECHNOLOGICAL AND COMPUTATIONAL ADVANCES THAT IMPROVE UNBIASED ACQUISITION OF EPIGENOMIC PROFILES HAVE SIGNIFICANTLY ENHANCED OUR APPRECIATION FOR THE COMPLEXITIES OF CHROMATIN ARCHITECTURE IN THE CONTEXTS OF DIVERSE IMMUNOLOGICAL CHALLENGES. CRITICAL ISSUES: KEY TO RESOLVING THE DISTINCT CHROMATIN SIGNATURES OF INNATE IMMUNE MEMORY IS A COMPREHENSIVE UNDERSTANDING OF THE PRECISE PHYSIOLOGICAL TARGETS OF REGULATORY PROTEINS THAT RECOGNIZE, DEPOSIT, AND REMOVE CHEMICAL MODIFICATIONS FROM CHROMATIN AS WELL AS OTHER GENE-REGULATING FACTORS. DRAWING FROM A RAPIDLY EXPANDING COMPENDIUM OF EXPERIMENTAL AND CLINICAL STUDIES, THIS REVIEW DETAILS A CURRENT PERSPECTIVE OF THE EPIGENETIC PATHWAYS THAT SUPPORT THE ADAPTED PHENOTYPES OF MONOCYTES AND MACROPHAGES. FUTURE DIRECTIONS: WE EXPLORE FUTURE STRATEGIES THAT ARE AIMED AT EXPLOITING THE MECHANISM OF TRAINED IMMUNITY TO IMPROVE THE PREVENTION AND TREATMENT OF INFECTIONS AND IMMUNE-MEDIATED CHRONIC DISORDERS. 2018 18 2137 30 EPIGENETIC INHERITANCE AND EVOLUTION: A PATERNAL PERSPECTIVE ON DIETARY INFLUENCES. THE EARLIEST INDICATIONS FOR PATERNALLY INDUCED TRANSGENERATIONAL EFFECTS FROM THE ENVIRONMENT TO FUTURE GENERATIONS WERE BASED ON A SMALL NUMBER OF LONG-TERM EPIDEMIOLOGICAL STUDIES AND SOME EMPIRICAL OBSERVATIONS. ONLY RECENTLY HAVE EXPERIMENTAL ANIMAL MODELS AND A FEW ANALYSES ON HUMAN DATA EXPLORED THE TRANSGENERATIONAL NATURE OF PHENOTYPIC CHANGES OBSERVED IN OFFSPRING. CHANGES INCLUDE MULTIPLE METABOLIC DISORDERS, CANCER AND OTHER CHRONIC DISEASES. THESE PHENOTYPES CANNOT ALWAYS BE EXPLAINED BY MENDELIAN INHERITANCE, DNA MUTATIONS OR GENETIC DAMAGE. HENCE, A NEW COMPELLING THEORY ON EPIGENETIC INHERITANCE IS GAINING INTEREST, PROVIDING NEW CONCEPTS THAT EXTEND DARWIN'S EVOLUTIONARY THEORY. EPIGENETIC ALTERATIONS OR "EPIMUTATIONS" ARE BEING CONSIDERED TO EXPLAIN TRANSGENERATIONAL INHERITANCE OF PARENTALLY ACQUIRED TRAITS. THE RESPONSIBLE MECHANISMS FOR THESE EPIMUTATIONS INCLUDE DNA METHYLATION, HISTONE MODIFICATION, AND RNA-MEDIATED EFFECTS. THIS REVIEW EXPLORES THE LITERATURE ON A NUMBER OF TIME-DEPENDENT ENVIRONMENTALLY INDUCED EPIGENETIC ALTERATIONS, SPECIFICALLY THOSE FROM DIETARY EXPOSURES. WE SUGGEST A ROLE FOR THE MALE GERM LINE AS ONE OF NATURE'S TOOLS TO CAPTURE MESSAGES FROM OUR CONTINUOUSLY CHANGING ENVIRONMENT AND TO TRANSFER THIS INFORMATION TO SUBSEQUENT GENERATIONS. FURTHER, WE OPEN THE DISCUSSION THAT THE PATERNALLY INHERITED EPIGENETIC INFORMATION MAY CONTRIBUTE TO EVOLUTIONARY ADAPTATION. 2015 19 2177 23 EPIGENETIC MECHANISMS OF HYPERGLYCEMIC MEMORY. RECENTLY THE CONCEPT EMERGED THAT PROLONGED EXPOSURE TO ALTERED METABOLIC CONDITIONS, INCLUDING HYPERGLYCEMIA, MAY EPIGENETICALLY IMPRINT HUMAN CELLS PERMITTING VERTICAL OR HORIZONTAL TRANSFER TO "DESCENDANTS". ALTHOUGH MECHANISTICALLY ILL UNDERSTOOD, THE HYPERGLYCEMIC/EPIGENETIC MEMORY MAY REPRESENT ONE OF THE MAJOR LIMITATIONS FOR THE APPLICATION OF CELL THERAPY TO TREATMENT OF CHRONIC HEART DISEASE WHERE A RELATIVELY PROLONGED PERIOD OF EX VIVO CELLULAR EXPANSION IS REQUIRED. HYPERGLYCEMIC MEMORY, IN FACT, SEEMS TO CONTRIBUTE TO THE ESTABLISHMENT OF AN EPIGENETIC "REMINISCENCE" OF THE ALTERED METABOLIC STATE, TO WHICH, CELLS FROM DISEASED BODIES HAVE BEEN EXPOSED. THIS REVIEW SUMMARIZES THE MOST RELEVANT CONCEPTS AND OBSERVATIONS ABOUT THE MECHANISMS UNDERLYING THE ONSET OF STABLE INFORMATION INSIDE THE EPIGENOME LEADING TO THE DEVELOPMENT OF A DISEASED PHENOTYPE. SPECIAL ATTENTION IS GIVEN TO EPIGENETIC DRUGS AND HOW THEY HAVE BEEN USED IN EXPERIMENTAL, PRECLINICAL AND CLINICAL SETTINGS TO TREAT DYSMETABOLISM, DIABETES AND THEIR COMPLICATIONS. 2014 20 2007 28 EPIGENETIC BASIS FOR FETAL ORIGINS OF AGE-RELATED DISEASE. THE CURRENT CONCEPT OF FETAL ORIGINS OF ADULT DISEASES DESCRIBES IN UTERO PROGRAMMING, OR ADAPTATION TO A SPECTRUM OF ADVERSE ENVIRONMENTAL CONDITIONS THAT ULTIMATELY LEADS TO INCREASED SUSCEPTIBILITY TO AGE-RELATED DISEASES (E.G., TYPE 2 DIABETES AND CARDIOVASCULAR DISEASE) LATER IN LIFE. ALTHOUGH THE PRECISE MECHANISM OF THIS BIOLOGICAL MEMORY REMAINS UNCLEAR, MOUNTING EVIDENCE SUGGESTS AN EPIGENETIC BASIS. THE INCREASED SUSCEPTIBILITY TO CHRONIC DISEASE AND INVOLVEMENT OF MULTIPLE ORGAN SYSTEMS THAT IS OBSERVED IS ANALOGOUS TO THE DECLINE IN RESISTANCE TO DISEASE THAT IS TYPICAL OF NORMAL AGING. ALTHOUGH THE CUMULATIVE ENVIRONMENT OVER THE COURSE OF A LIFETIME CAN INDUCE INCREASING EPIGENETIC DYSREGULATION, WE PROPOSE THAT ADVERSE EVENTS THAT OCCUR DURING EARLY DEVELOPMENT CAN INDUCE SIGNIFICANT ADDITIONAL DYSREGULATION OF THE EPIGENOME. HERE, WE DESCRIBE THE CURRENT EVIDENCE FOR FETAL ORIGINS OF ADULT DISEASE AND THE ASSOCIATED ROLE OF EPIGENETIC DYSREGULATION. IN ADDITION, WE PRESENT A NEW PERSPECTIVE ON THE INDUCTION OF EPIGENETIC ALTERATIONS IN UTERO, WHICH SUBSEQUENTLY LEAD TO AN AGING PHENOTYPE MARKED BY INCREASED SUSCEPTIBILITY TO AGE-RELATED DISEASES. 2010