1 1926 148 ENVIRONMENTAL EPIGENETICS OF ASTHMA: AN UPDATE. ASTHMA, A CHRONIC INFLAMMATORY DISORDER OF THE AIRWAY, IS INFLUENCED BY INTERPLAY BETWEEN GENETIC AND ENVIRONMENTAL FACTORS NOW KNOWN TO BE MEDIATED BY EPIGENETICS. ABERRANT DNA METHYLATION, ALTERED HISTONE MODIFICATIONS, SPECIFIC MICRORNA EXPRESSION, AND OTHER CHROMATIN ALTERATIONS ORCHESTRATE A COMPLEX EARLY-LIFE REPROGRAMMING OF IMMUNE T-CELL RESPONSE, DENDRITIC CELL FUNCTION, MACROPHAGE ACTIVATION, AND A BREACH OF AIRWAY EPITHELIAL BARRIER THAT DICTATES ASTHMA RISK AND SEVERITY IN LATER LIFE. ADULT-ONSET ASTHMA IS UNDER ANALOGOUS REGULATION. THE SHARP INCREASE IN ASTHMA PREVALENCE OVER THE PAST 2 OR 3 DECADES AND THE LARGE VARIATIONS AMONG POPULATIONS OF SIMILAR RACIAL/ETHNIC BACKGROUND BUT DIFFERENT ENVIRONMENTAL EXPOSURES FAVORS A STRONG CONTRIBUTION OF ENVIRONMENTAL FACTORS. THIS REVIEW ADDRESSES THE FUNDAMENTAL QUESTION OF WHETHER ENVIRONMENTAL INFLUENCES ON ASTHMA RISK, SEVERITY, AND STEROID RESISTANCE ARE PARTLY DUE TO DIFFERENTIAL EPIGENETIC MODULATIONS. CURRENT KNOWLEDGE ON THE EPIGENETIC EFFECTS OF TOBACCO SMOKE, MICROBIAL ALLERGENS, OXIDANTS, AIRBORNE PARTICULATE MATTER, DIESEL EXHAUST PARTICLES, POLYCYCLIC AROMATIC HYDROCARBONS, DIETARY METHYL DONORS AND OTHER NUTRITIONAL FACTORS, AND DUST MITES IS DISCUSSED. EXCITING FINDINGS HAVE BEEN GENERATED BY RAPID TECHNOLOGICAL ADVANCES AND WELL-DESIGNED EXPERIMENTAL AND POPULATION STUDIES. THE DISCOVERY AND VALIDATION OF EPIGENETIC BIOMARKERS LINKED TO EXPOSURE, ASTHMA, OR BOTH MIGHT LEAD TO BETTER EPIGENOTYPING OF RISK, PROGNOSIS, TREATMENT PREDICTION, AND DEVELOPMENT OF NOVEL THERAPIES. 2010 2 5552 44 ROLE OF EPIGENETICS IN THE PATHOGENESIS OF ASTHMA. ASTHMA IS A COMPLEX, HETEROGENEOUS AND CHRONIC AIRWAY INFLAMMATORY DISEASE WITH DIFFERENT CLINICAL PHENOTYPES CAUSED BY DIVERSE TRIGGERS AND PATHOPHYSIOLOGICAL MECHANISMS. ASTHMA HERITABILITY HAS BEEN ESTABLISHED IN MANY GENETIC STUDIES BUT IT IS EVIDENT THAT ONLY GENETIC ELEMENTS ARE NOT RESPONSIBLE FOR THE DEVELOPMENT OF ASTHMA. INCREASING RATE OF ASTHMA INCIDENCE DURING PAST DECADES HAS IMPLICATED THE ROLE OF EPIGENETICS IN DEVELOPMENT OF ASTHMA. ENVIRONMENTAL FACTORS PERFORM AS INITIATOR SIGNALS THROUGH EPIGENETIC MECHANISMS. THREE EPIGENETIC MECHANISMS HAVE BEEN IDENTIFIED, INCLUDING DNA METHYLATION, HISTONE MODIFICATIONS, AND SMALL NONCODING RNAS. THESE MECHANISMS REGULATE THE IMMUNE RESPONSES AND INFLAMMATORY GENES EXPRESSION IN ASTHMA AND ALLERGY. THIS REVIEW EXPLAINS THE ROLE OF EPIGENETIC MODIFICATIONS IN CONTROLLING TH2 RESPONSE AND IGE PRODUCTION IN ASTHMA AND ALSO BRIEFLY OVERVIEWS THE ROLE OF ENVIRONMENTAL FACTORS SUCH AS POLLUTIONS, ALLERGENS, PRENATAL EXPOSURES AND DIET IN DEVELOPING ASTHMA. RECOGNIZING ENVIRONMENTAL RISK FACTORS AND THEIR EFFECTS ON EPIGENETIC MECHANISMS WOULD BE OF GREAT INTEREST FOR PROGNOSTIC AND PREVENTIVE ASPECT IN TREATMENT OF ASTHMA. 2017 3 1924 48 ENVIRONMENTAL EPIGENETICS AND ITS IMPLICATION ON DISEASE RISK AND HEALTH OUTCOMES. THIS REVIEW FOCUSES ON HOW ENVIRONMENTAL FACTORS THROUGH EPIGENETICS MODIFY DISEASE RISK AND HEALTH OUTCOMES. MAJOR EPIGENETIC EVENTS, SUCH AS HISTONE MODIFICATIONS, DNA METHYLATION, AND MICRORNA EXPRESSION, ARE DESCRIBED. THE FUNCTION OF DOSE, DURATION, COMPOSITION, AND WINDOW OF EXPOSURE IN REMODELING THE INDIVIDUAL'S EPIGENETIC TERRAIN AND DISEASE SUSCEPTIBILITY ARE ADDRESSED. THE IDEAS OF LIFELONG EDITING OF EARLY-LIFE EPIGENETIC MEMORIES, TRANSGENERATIONAL EFFECTS THROUGH GERMLINE TRANSMISSION, AND THE POTENTIAL ROLE OF HYDROXYLMETHYLATION OF CYTOSINE IN DEVELOPMENTAL REPROGRAMMING ARE DISCUSSED. FINALLY, THE EPIGENETIC EFFECTS OF SEVERAL MAJOR CLASSES OF ENVIRONMENTAL FACTORS ARE REVIEWED IN THE CONTEXT OF PATHOGENESIS OF DISEASE. THESE INCLUDE ENDOCRINE DISRUPTORS, TOBACCO SMOKE, POLYCYCLIC AROMATIC HYDROCARBONS, INFECTIOUS PATHOGENS, PARTICULATE MATTER, DIESEL EXHAUST PARTICLES, DUST MITES, FUNGI, HEAVY METALS, AND OTHER INDOOR AND OUTDOOR POLLUTANTS. WE CONCLUDE THAT THE SUMMATION OF EPIGENETIC MODIFICATIONS INDUCED BY MULTIPLE ENVIRONMENTAL EXPOSURES, ACCUMULATED OVER TIME, REPRESENTED AS BROAD OR NARROW, ACUTE OR CHRONIC, DEVELOPMENTAL OR LIFELONG, MAY PROVIDE A MORE PRECISE ASSESSMENT OF RISK AND CONSEQUENCES. FUTURE INVESTIGATIONS MAY FOCUS ON THEIR USE AS READOUTS OR BIOMARKERS OF THE TOTALITY OF PAST EXPOSURE FOR THE PREDICTION OF FUTURE DISEASE RISK AND THE PRESCRIPTION OF EFFECTIVE COUNTERMEASURES. 2012 4 2330 42 EPIGENETIC REGULATION OF IMMUNE FUNCTION IN ASTHMA. ASTHMA IS A COMMON COMPLEX RESPIRATORY DISEASE CHARACTERIZED BY CHRONIC AIRWAY INFLAMMATION AND PARTIALLY REVERSIBLE AIRFLOW OBSTRUCTION RESULTING FROM GENETIC AND ENVIRONMENTAL DETERMINANTS. BECAUSE EPIGENETIC MARKS INFLUENCE GENE EXPRESSION AND CAN BE MODIFIED BY BOTH ENVIRONMENTAL EXPOSURES AND GENETIC VARIATION, THEY ARE INCREASINGLY RECOGNIZED AS RELEVANT TO THE PATHOGENESIS OF ASTHMA AND MAY BE A KEY LINK BETWEEN ENVIRONMENTAL EXPOSURES AND ASTHMA SUSCEPTIBILITY. UNLIKE CHANGES TO DNA SEQUENCE, EPIGENETIC SIGNATURES ARE DYNAMIC AND REVERSIBLE, CREATING AN OPPORTUNITY FOR NOT ONLY THERAPEUTIC TARGETS BUT MAY SERVE AS BIOMARKERS TO FOLLOW DISEASE COURSE AND IDENTIFY MOLECULAR SUBTYPES IN HETEROGENEOUS DISEASES SUCH AS ASTHMA. IN THIS REVIEW, WE WILL EXAMINE THE RELATIONSHIP BETWEEN ASTHMA AND 3 KEY EPIGENETIC PROCESSES THAT MODIFY GENE EXPRESSION: DNA METHYLATION, MODIFICATION OF HISTONE TAILS, AND NONCODING RNAS. IN ADDITION TO PRESENTING A COMPREHENSIVE ASSESSMENT OF THE EXISTING EPIGENETIC STUDIES FOCUSING ON IMMUNE REGULATION IN ASTHMA, WE WILL DISCUSS FUTURE DIRECTIONS FOR EPIGENETIC INVESTIGATION IN ALLERGIC AIRWAY DISEASE. 2022 5 396 39 AN UPDATE ON EPIGENETICS AND CHILDHOOD RESPIRATORY DISEASES. EPIGENETIC MECHANISMS, DEFINED AS CHANGES IN PHENOTYPE OR GENE EXPRESSION CAUSED BY MECHANISMS OTHER THAN CHANGES IN THE UNDERLYING DNA SEQUENCE, HAVE BEEN PROPOSED TO CONSTITUTE A LINK BETWEEN GENETIC AND ENVIRONMENTAL FACTORS THAT AFFECT COMPLEX DISEASES. RECENT STUDIES SHOW THAT DNA METHYLATION, ONE OF THE KEY EPIGENETIC MECHANISMS, IS ALTERED IN CHILDREN EXPOSED TO AIR POLLUTANTS AND ENVIRONMENTAL TOBACCO SMOKE EARLY IN LIFE. SEVERAL CANDIDATE GENE STUDIES ON EPIGENETICS HAVE BEEN PUBLISHED TO DATE, BUT IT IS ONLY RECENTLY THAT GLOBAL METHYLATION ANALYSES HAVE BEEN PERFORMED FOR RESPIRATORY DISORDERS SUCH AS ASTHMA AND CHRONIC OBSTRUCTIVE PULMONARY DISEASE. HOWEVER, LARGE-SCALE STUDIES WITH ADEQUATE POWER ARE YET TO BE PRESENTED IN CHILDREN, AND IMPLICATIONS FOR CLINICAL USE REMAIN TO BE EVALUATED. IN THIS REVIEW, WE SUMMARIZE THE RECENT ADVANCES IN EPIGENETICS AND RESPIRATORY DISORDERS IN CHILDREN, WITH A MAIN FOCUS ON METHODOLOGICAL CHALLENGES AND ANALYSES RELATED TO PHENOTYPE AND EXPOSURE USING GLOBAL METHYLATION APPROACHES. 2014 6 6735 45 WHAT HAVE MECHANISTIC STUDIES TAUGHT US ABOUT CHILDHOOD ASTHMA? CHILDHOOD ASTHMA IS A CHRONIC HETEROGENEOUS SYNDROME CONSISTING OF DIFFERENT DISEASE ENTITIES OR PHENOTYPES. THE IMMUNOLOGIC AND CELLULAR PROCESSES THAT OCCUR DURING ASTHMA DEVELOPMENT ARE STILL NOT FULLY UNDERSTOOD BUT REPRESENT DISTINCT ENDOTYPES. MECHANISTIC STUDIES HAVE EXAMINED THE ROLE OF GENE EXPRESSION, PROTEIN LEVELS, AND CELL TYPES IN EARLY LIFE DEVELOPMENT AND THE MANIFESTATION OF ASTHMA, MANY UNDER THE INFLUENCE OF ENVIRONMENTAL STIMULI, WHICH CAN BE BOTH PROTECTIVE AND RISK FACTORS FOR ASTHMA. GENETIC VARIANTS CAN REGULATE GENE EXPRESSION, CONTROLLED PARTLY BY DIFFERENT EPIGENETIC MECHANISMS. IN ADDITION, ENVIRONMENTAL FACTORS, SUCH AS LIVING SPACE, NUTRITION, AND SMOKING, CAN CONTRIBUTE TO THESE MECHANISMS. ALL OF THESE FACTORS PRODUCE MODIFICATIONS IN GENE EXPRESSION THAT CAN ALTER THE DEVELOPMENT AND FUNCTION OF IMMUNE AND EPITHELIAL CELLS AND SUBSEQUENTLY DIFFERENT TRAJECTORIES OF CHILDHOOD ASTHMA. THESE EARLY CHANGES IN A PARTIALLY IMMATURE IMMUNE SYSTEM CAN HAVE DRAMATIC EFFECTS (E.G., CAUSING DYSREGULATION), WHICH IN TURN CONTRIBUTE TO DIFFERENT DISEASE ENDOTYPES AND MAY HELP TO EXPLAIN DIFFERENTIAL RESPONSIVENESS TO ASTHMA TREATMENT. IN THIS REVIEW, WE SUMMARIZE PUBLISHED STUDIES THAT HAVE AIMED TO UNCOVER DISTINCT MECHANISMS IN CHILDHOOD ASTHMA, CONSIDERING GENETICS, EPIGENETICS, AND ENVIRONMENT. MOREOVER, A DISCUSSION OF NEW, POWERFUL TOOLS FOR SINGLE-CELL IMMUNOLOGIC ASSAYS FOR PHENOTYPIC AND FUNCTIONAL ANALYSIS IS INCLUDED, WHICH PROMISE NEW MECHANISTIC INSIGHTS INTO CHILDHOOD ASTHMA DEVELOPMENT AND THERAPEUTIC AND PREVENTIVE STRATEGIES. 2023 7 4094 39 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 8 3028 32 GENETICS OF COMPLEX AIRWAY DISEASE. THE PAST 3 YEARS HAVE SEEN HIGHLY SIGNIFICANT GENETIC EFFECTS IDENTIFIED FOR A WIDE VARIETY OF COMMON COMPLEX DISEASES, INCLUDING THE AIRWAY DISORDERS OF ASTHMA AND CHRONIC OBSTRUCTIVE PULMONARY DISEASE. IT APPEARS THAT ONLY A PORTION OF THE GENETICALLY MEDIATED SUSCEPTIBILITY TO COMPLEX DISEASES HAS BEEN IDENTIFIED, AND THERE IS MUCH LEFT TO BE DISCOVERED. THIS REVIEW BRIEFLY DESCRIBES THE RESULTS OF THE GENOME-WIDE ASSOCIATION STUDIES OF ASTHMA AND GIVES AN OVERVIEW OF THE PARALLEL AND INCREASINGLY LARGE-SCALE STUDIES THAT ARE TAKING PLACE WITH CHRONIC OBSTRUCTIVE PULMONARY DISEASE. THE FUTURE IMPACT IS DISCUSSED OF TECHNOLOGICAL ADVANCES THAT ALLOW INCREASINGLY LARGE-SCALE GENE EXPRESSION STUDIES, NEXT-GENERATION SEQUENCING, AND GENOME-WIDE TESTING FOR EPIGENETIC EFFECTS. THE USE OF GENETIC TECHNOLOGY TO EXAMINE THE AIRWAY MICROBIOTA THAT INTERACT WITH THE MUCOSA IN HEALTH AND DISEASE IS DESCRIBED. 2011 9 3421 38 HUMAN MATTERS IN ASTHMA: CONSIDERING THE MICROBIOME IN PULMONARY HEALTH. MICROBIAL COMMUNITIES FORM AN IMPORTANT SYMBIOTIC ECOSYSTEM WITHIN HUMANS AND HAVE DIRECT EFFECTS ON HEALTH AND WELL-BEING. NUMEROUS EXOGENOUS FACTORS INCLUDING AIRBORNE TRIGGERS, DIET, AND DRUGS IMPACT THESE ESTABLISHED, BUT FRAGILE COMMUNITIES ACROSS THE HUMAN LIFESPAN. CROSSTALK BETWEEN THE MUCOSAL MICROBIOTA AND THE IMMUNE SYSTEM AS WELL AS THE GUT-LUNG AXIS HAVE DIRECT CORRELATIONS TO IMMUNE BIAS THAT MAY PROMOTE CHRONIC DISEASES LIKE ASTHMA. ASTHMA INITIATION AND PATHOGENESIS ARE MULTIFACETED AND COMPLEX WITH INPUT FROM GENETIC, EPIGENETIC, AND ENVIRONMENTAL COMPONENTS. IN THIS REVIEW, WE SUMMARIZE AND DISCUSS THE ROLE OF THE AIRWAY MICROBIOME IN ASTHMA, AND HOW THE ENVIRONMENT, DIET AND THERAPEUTICS IMPACT THIS LOW BIOMASS COMMUNITY OF MICROORGANISMS. WE ALSO FOCUS THIS REVIEW ON THE PEDIATRIC AND BLACK POPULATIONS AS HIGH-RISK GROUPS REQUIRING SPECIAL ATTENTION, EMPHASIZING THAT THE WHOLE PATIENT MUST BE CONSIDERED DURING TREATMENT. ALTHOUGH NEW CULTURE-INDEPENDENT TECHNIQUES HAVE BEEN DEVELOPED AND ARE MORE ACCESSIBLE TO RESEARCHERS, THE EXACT CONTRIBUTION THE AIRWAY MICROBIOME MAKES IN ASTHMA PATHOGENESIS IS NOT WELL UNDERSTOOD. UNDERSTANDING HOW THE AIRWAY MICROBIOME, AS A LIVING ENTITY IN THE RESPIRATORY TRACT, PARTICIPATES IN LUNG IMMUNITY DURING THE DEVELOPMENT AND PROGRESSION OF ASTHMA MAY LEAD TO CRITICAL NEW TREATMENTS FOR ASTHMA, INCLUDING POPULATION-TARGETED INTERVENTIONS, OR EVEN MORE EFFECTIVE ADMINISTRATION OF CURRENTLY AVAILABLE THERAPEUTICS. 2022 10 2160 27 EPIGENETIC MECHANISMS IN ASTHMA. ASTHMA AND ALLERGIC DISEASES ARE AMONG THE MOST PREVALENT CHRONIC NONCOMMUNICABLE DISEASES OF CHILDHOOD, BUT THE UNDERLYING PATHOGENETIC MECHANISMS ARE POORLY UNDERSTOOD. BECAUSE EPIGENETIC MECHANISMS LINK GENE REGULATION TO ENVIRONMENTAL CUES AND DEVELOPMENTAL TRAJECTORIES, THEIR CONTRIBUTION TO ASTHMA AND ALLERGY PATHOGENESIS IS UNDER ACTIVE INVESTIGATION. DNA METHYLATION SIGNATURES ASSOCIATED WITH CONCURRENT DISEASE AND WITH THE DEVELOPMENT OF ASTHMA DURING CHILDHOOD ASTHMA HAVE BEEN IDENTIFIED, BUT THEIR SIGNIFICANCE IS NOT EASILY INTERPRETABLE. ON THE OTHER HAND, THE CHARACTERIZATION OF EARLY EPIGENETIC PREDICTORS OF ASTHMA POINTS TO A POTENTIAL ROLE OF EPIGENETIC MECHANISMS IN REGULATING THE INCEPTION OF, AND THE SUSCEPTIBILITY TO, THIS DISEASE. 2016 11 2984 39 GENETIC DETERMINANTS OF POOR RESPONSE TO TREATMENT IN SEVERE ASTHMA. SEVERE ASTHMA IS A MULTIFACTORIAL DISORDER WITH MARKED PHENOTYPIC HETEROGENEITY AND COMPLEX INTERACTIONS BETWEEN GENETICS AND ENVIRONMENTAL RISK FACTORS, WHICH COULD, AT LEAST IN PART, EXPLAIN WHY DURING STANDARD PHARMACOLOGIC TREATMENT, MANY PATIENTS REMAIN POORLY CONTROLLED AND AT AN INCREASED RISK OF AIRWAY REMODELING AND DISEASE PROGRESSION. THE CONCEPT OF "PRECISION MEDICINE" TO BETTER SUIT INDIVIDUAL UNIQUE NEEDS IS AN EMERGING TREND IN THE MANAGEMENT OF CHRONIC RESPIRATORY DISEASES. OVER THE PAST FEW YEARS, GENOME-WIDE ASSOCIATION STUDIES (GWAS) HAVE REVEALED NOVEL PHARMACOGENETIC VARIANTS RELATED TO RESPONSES TO INHALED CORTICOSTEROIDS AND THE CLINICAL EFFICACY OF BRONCHODILATORS. OPTIMAL CLINICAL RESPONSE TO TREATMENT MAY VARY BETWEEN RACIAL/ETHNIC GROUPS OR INDIVIDUALS DUE TO GENETIC DIFFERENCES. IT IS ALSO PLAUSIBLE TO ASSUME THAT EPIGENETIC FACTORS PLAY A KEY ROLE IN THE MODULATION OF GENE EXPRESSION PATTERNS AND INFLAMMATORY CYTOKINES. REMARKABLY, SPECIFIC GENETIC VARIANTS RELATED TO TREATMENT EFFECTIVENESS MAY INDICATE PROMISING PATHWAYS FOR NOVEL THERAPIES IN SEVERE ASTHMA. IN THIS REVIEW, WE PROVIDE A CONCISE UPDATE OF GENETIC DETERMINANTS OF POOR RESPONSE TO TREATMENT IN SEVERE ASTHMA AND FUTURE DIRECTIONS IN THE FIELD. 2021 12 2531 30 EPIGENETICS IN ASTHMA. PURPOSE OF REVIEW: ASTHMA IS ONE OF THE MOST COMMON CHRONIC RESPIRATORY DISEASES LINKED WITH INCREASED MORBIDITY AND HEALTHCARE UTILIZATION. THE UNDERLYING PATHOPHYSIOLOGICAL PROCESSES AND CAUSAL RELATIONSHIPS OF ASTHMA WITH EPIGENETIC MECHANISMS ARE PARTIALLY UNDERSTOOD. HERE WE REVIEW HUMAN STUDIES OF EPIGENETIC MECHANISMS IN ASTHMA, WITH A SPECIAL FOCUS ON DNA METHYLATION. RECENT FINDINGS: EPIGENETIC STUDIES OF CHILDHOOD ASTHMA HAVE IDENTIFIED SPECIFIC METHYLATION SIGNATURES ASSOCIATED WITH ALLERGIC INFLAMMATION IN THE AIRWAY AND IMMUNE CELLS, DEMONSTRATING A REGULATORY ROLE FOR METHYLATION IN ASTHMA PATHOGENESIS. DESPITE THESE NOVEL FINDINGS, ADDITIONAL RESEARCH IN THE ROLE OF EPIGENETIC MECHANISMS UNDERLYING ASTHMA ENDOTYPES IS NEEDED. SIMILARLY, STUDIES OF HISTONE MODIFICATIONS ARE ALSO LACKING IN ASTHMA. FUTURE STUDIES OF EPIGENETIC MECHANISMS IN ASTHMA WILL BENEFIT FROM DATA INTEGRATION IN WELL PHENOTYPED COHORTS. THIS REVIEW PROVIDES AN OVERVIEW OF THE CURRENT LITERATURE ON EPIGENETIC STUDIES IN HUMAN ASTHMA, WITH SPECIAL EMPHASIS ON METHYLATION AND CHILDHOOD ASTHMA. 2019 13 2492 33 EPIGENETICS AND CHILDHOOD ASTHMA: CURRENT EVIDENCE AND FUTURE RESEARCH DIRECTIONS. ASTHMA IS THE MOST COMMON CHRONIC DISEASE OF CHILDHOOD, AFFECTING ONE IN EIGHT CHILDREN IN THE USA AND WORLDWIDE. IT IS A COMPLEX DISEASE, INFLUENCED BY BOTH ENVIRONMENTAL EXPOSURES AND GENETIC FACTORS. ALTHOUGH EPIGENETIC MODIFICATIONS (DNA METHYLATION, HISTONE MODIFICATION AND MIRNA) CAN AFFECT TRANSCRIPTIONAL ACTIVITY IN MULTIPLE GENETIC PATHWAYS RELEVANT FOR ASTHMA DEVELOPMENT, VERY LIMITED WORK HAS BEEN CARRIED OUT SO FAR TO EXAMINE THE ROLE OF EPIGENETIC VARIATIONS ON ASTHMA DEVELOPMENT AND MANAGEMENT. THIS REVIEW PROVIDES A BRIEF OVERVIEW OF EPIGENETIC MODIFICATIONS, SUMMARIZES RECENT FINDINGS, AND DISCUSSES SOME OF THE MAJOR METHODOLOGICAL CONCERNS THAT ARE RELEVANT FOR ASTHMA EPIGENETICS. 2012 14 2530 34 EPIGENETICS IN ALLERGIC DISEASES. PURPOSE OF REVIEW: ALLERGIC DISEASES ARE AMONG THE MOST PREVALENT CHRONIC DISEASES OF CHILDHOOD, AFFECTING MORE THAN 7 MILLION CHILDREN IN THE UNITED STATES. EPIDEMIOLOGICAL EVIDENCE SUPPORTS THE IDEA THAT THE INCEPTION OF ALLERGIC DISEASES IS TYPICALLY BEFORE THE PRESCHOOL YEARS, EVEN WHEN CHRONIC SYMPTOMS DO NOT EMERGE UNTIL ADULTHOOD. THE ROLE OF EPIGENETIC MECHANISMS (PARTICULARLY DNA METHYLATION) IN ALLERGIC DISEASE IS UNDER ACTIVE INVESTIGATION BECAUSE THESE MECHANISMS ARE KNOWN TO BE AT THE INTERFACE OF GENE REGULATION, ENVIRONMENTAL STIMULI, AND DEVELOPMENTAL PROCESSES, ALL OF WHICH ARE ESSENTIAL FOR THE PATHOGENESIS FOR ASTHMA AND ALLERGY. THIS ARTICLE SPECIFICALLY REVIEWS GENOME-WIDE DNA METHYLATION STUDIES IN ALLERGIC DISEASE. RECENT FINDINGS: DIFFERENTIAL DNA METHYLATION AT SPECIFIC REGIONS APPEARS TO BE ASSOCIATED WITH CONCURRENT ALLERGIC DISEASE. A FEW STUDIES HAVE IDENTIFIED METHYLATION SIGNATURES PREDICTIVE OF DISEASE. SUMMARY: DNA METHYLATION SIGNATURES HAVE BEEN SHOWN TO BE ASSOCIATED WITH SEVERAL ALLERGIC DISEASE PHENOTYPES, TYPICALLY CONCURRENTLY WITH DISEASE. THE FEW THAT HAVE BEEN FOUND TO PRECEDE DIAGNOSIS ARE ESPECIALLY INTERESTING BECAUSE THEY HIGHLIGHT AN EARLY TRAJECTORY TO DISEASE. 2015 15 738 30 CANCER SUSCEPTIBILITY: EPIGENETIC MANIFESTATION OF ENVIRONMENTAL EXPOSURES. CANCER IS A DISEASE THAT RESULTS FROM BOTH GENETIC AND EPIGENETIC CHANGES. DISCORDANT PHENOTYPES AND VARYING INCIDENCES OF COMPLEX DISEASES SUCH AS CANCER IN MONOZYGOTIC TWINS AS WELL AS GENETICALLY IDENTICAL LABORATORY ANIMALS HAVE LONG BEEN ATTRIBUTED TO DIFFERENCES IN ENVIRONMENTAL EXPOSURES. ACCUMULATING EVIDENCE INDICATES, HOWEVER, THAT DISPARITIES IN GENE EXPRESSION RESULTING FROM VARIABLE MODIFICATIONS IN DNA METHYLATION AND CHROMATIN STRUCTURE IN RESPONSE TO THE ENVIRONMENT ALSO PLAY A ROLE IN DIFFERENTIAL SUSCEPTIBILITY TO DISEASE. DESPITE A GROWING CONSENSUS ON THE IMPORTANCE OF EPIGENETICS IN THE ETIOLOGY OF CHRONIC HUMAN DISEASES, THE GENES MOST PRONE TO EPIGENETIC DYSREGULATION ARE INCOMPLETELY DEFINED. MOREOVER, NEITHER THE ENVIRONMENTAL AGENTS MOST STRONGLY AFFECTING THE EPIGENOME NOR THE CRITICAL WINDOWS OF VULNERABILITY TO ENVIRONMENTALLY INDUCED EPIGENETIC ALTERATIONS ARE ADEQUATELY CHARACTERIZED. THESE MAJOR DEFICITS IN KNOWLEDGE MARKEDLY IMPAIR OUR ABILITY TO UNDERSTAND FULLY THE ETIOLOGY OF CANCER AND THE IMPORTANCE OF THE EPIGENOME IN DIAGNOSING AND PREVENTING THIS DEVASTATING DISEASE. 2007 16 2519 47 EPIGENETICS AND THE ENVIRONMENT IN AIRWAY DISEASE: ASTHMA AND ALLERGIC RHINITIS. ASTHMA AND RHINITIS ARE COMPLEX, HETEROGENEOUS DISEASES CHARACTERIZED BY CHRONIC INFLAMMATION OF THE UPPER AND LOWER AIRWAYS. WHILE GENOME-WIDE ASSOCIATION STUDIES (GWAS) HAVE IDENTIFIED A NUMBER OF SUSCEPTIBLE LOCI AND CANDIDATE GENES ASSOCIATED WITH THE PATHOGENESIS OF ASTHMA AND ALLERGIC RHINITIS (AR), THE RISK-ASSOCIATED ALLELES ACCOUNT FOR ONLY A VERY SMALL PERCENT OF THE GENETIC RISK. IN ALLERGIC AIRWAY AND OTHER COMPLEX DISEASES, IT IS THOUGHT THAT EPIGENETIC MODIFICATIONS, INCLUDING DNA METHYLATION, HISTONE MODIFICATIONS, AND NON-CODING MICRORNAS, CAUSED BY COMPLEX INTERACTIONS BETWEEN THE UNDERLYING GENOME AND THE ENVIRONMENT MAY ACCOUNT FOR SOME OF THIS "MISSING HERITABILITY" AND MAY EXPLAIN THE HIGH DEGREE OF PLASTICITY IN IMMUNE RESPONSES. IN THIS CHAPTER, WE WILL FOCUS ON THE CURRENT KNOWLEDGE OF CLASSICAL EPIGENETIC MODIFICATIONS, DNA METHYLATION AND HISTONE MODIFICATIONS, AND THEIR POTENTIAL ROLE IN ASTHMA AND AR. IN PARTICULAR, WE WILL REVIEW EPIGENETIC VARIATIONS ASSOCIATED WITH MATERNAL AIRWAY DISEASE, DEMOGRAPHICS, ENVIRONMENT, AND NON-SPECIFIC ASSOCIATIONS. THE ROLE OF SPECIFIC GENETIC HAPLOTYPES IN ENVIRONMENTALLY INDUCED EPIGENETIC CHANGES ARE ALSO DISCUSSED. A MAJOR LIMITATION OF MANY OF THE CURRENT STUDIES OF ASTHMA EPIGENETICS IS THAT THEY EVALUATE EPIGENETIC MODIFICATIONS IN BOTH ALLERGIC AND NON-ALLERGIC ASTHMA, MAKING IT DIFFICULT TO DISTINGUISH THOSE EPIGENETIC MODIFICATIONS THAT MEDIATE ALLERGIC ASTHMA FROM THOSE THAT MEDIATE NON-ALLERGIC ASTHMA. ADDITIONALLY, MOST DNA METHYLATION STUDIES IN ASTHMA USE PERIPHERAL OR CORD BLOOD DUE TO POOR ACCESSIBILITY OF AIRWAY CELLS OR TISSUE. UNLIKE DNA SEQUENCES, EPIGENETIC ALTERATIONS ARE QUITE CELL- AND TISSUE-SPECIFIC, AND EPIGENETIC CHANGES FOUND IN AIRWAY TISSUE OR CELLS MAY BE DISCORDANT FROM THAT OF CIRCULATING BLOOD. THESE TWO CONFOUNDING FACTORS SHOULD BE CONSIDERED WHEN REVIEWING EPIGENETIC STUDIES IN ALLERGIC AIRWAY DISEASE. 2020 17 6811 41 [EPIGENETICS, ENVIRONMENT AND ASTHMA]. ASTHMA IS A CHRONIC INFLAMMATORY DISEASE OF THE RESPIRATORY TRACT WITH A COMPLEX GENETIC BACKGROUND INFLUENCED BY THE EXPOSITION TO A SERIES OF ENVIRONMENTAL FACTORS. GENETIC STUDIES CAN ONLY ELUCIDATE PART OF THE HERITABILITY AND SUSCEPTIBILITY OF ASTHMA AND EVEN THOUGH SEVERAL DISEASES HAVE AN EVIDENT GENETIC ETIOLOGY, ONLY A FRACTION OF THE GENES INVOLVED IN THEIR PATHOGENICITY HAVE BEEN IDENTIFIED. THE EPIGENETIC REGULATION OF THE LATTER IS A FACT ONE SHOULD BEAR IN MIND IN ORDER TO EXPLAIN THE MAJOR TRIGGERS OF DISEASES WHOSE UNDERSTANDING IS COMPLICATED, SUCH AS ALLERGIES AND ASTHMA. EXTERNAL STIMULUS SUCH AS NOURISHMENT, STRESS, PHYSICAL ACTIVITY, ATMOSPHERIC POLLUTION, TOBACCO SMOKING AND ALCOHOL DRINKING CAN INDUCE EITHER GENE SILENCING OR GENE EXPRESSION. IN THIS REGARD, EPIGENETICS CAN EXPLAIN HOW THESE ENVIRONMENTAL FACTORS INFLUENCE OUR GENETIC INHERITANCE. THERE IS GROWING EVIDENCE THAT BACKS-UP THE FACT THAT DNA METHYLATION, HISTONE POST-TRANSLATIONAL MODIFICATION AND MICRORNA EXPRESSION ARE INFLUENCED BY THE ENVIRONMENT. THIS HELPS EXPLAINING HOW SEVERAL OF THE RISK FACTORS MENTIONED CONTRIBUTE TO THE DEVELOPMENT AND INHERITANCE OF ASTHMA. IN THIS REVIEW, DIFFERENT ENVIRONMENTAL FACTORS AND THEIR RELATION WITH THE MAIN EPIGENETIC REGULATORY MECHANISMS WILL BE ANALYZED, AS WELL AS THEIR POSSIBLE ROLE IN THE DEVELOPMENT OF ASTHMA. 2014 18 1546 31 DNA METHYLATION IN NASAL EPITHELIUM: STRENGTHS AND LIMITATIONS OF AN EMERGENT BIOMARKER FOR CHILDHOOD ASTHMA. ASTHMA IS ONE OF THE MOST WIDESPREAD CHRONIC RESPIRATORY CONDITIONS. THIS DISEASE PRIMARILY DEVELOPS IN CHILDHOOD AND IS INFLUENCED BY DIFFERENT FACTORS, MAINLY GENETICS AND ENVIRONMENTAL FACTORS. DNA METHYLATION IS AN EPIGENETIC MECHANISM WHICH MAY REPRESENT A BRIDGE BETWEEN THESE TWO FACTORS, PROVIDING A TOOL TO COMPREHEND THE INTERACTION BETWEEN GENETICS AND ENVIRONMENT. MOST EPIDEMIOLOGICAL STUDIES IN THIS FIELD HAVE BEEN CONDUCTED USING BLOOD SAMPLES, ALTHOUGH DNA METHYLATION MARKS IN BLOOD MAY NOT BE RELIABLE FOR DRAWING EXHAUSTIVE CONCLUSIONS ABOUT DNA METHYLATION IN THE AIRWAYS. BECAUSE OF THE ROLE OF NASAL EPITHELIUM IN ASTHMA AND THE TISSUE SPECIFICITY OF DNA METHYLATION, STUDYING THE RELATIONSHIP BETWEEN DNA METHYLATION AND CHILDHOOD ASTHMA MIGHT REVEAL CRUCIAL INFORMATION ABOUT THIS WIDESPREAD RESPIRATORY DISEASE. THE PURPOSE OF THIS REVIEW IS TO DESCRIBE CURRENT FINDINGS IN THIS FIELD OF RESEARCH. WE WILL PRESENT A VIEWPOINT OF SELECTED STUDIES, CONSIDER STRENGTHS AND LIMITATIONS, AND PROPOSE FUTURE RESEARCH IN THIS AREA. 2020 19 3706 34 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 20 2651 39 EPIGENOMICS AND TRANSCRIPTOMICS IN THE PREDICTION AND DIAGNOSIS OF CHILDHOOD ASTHMA: ARE WE THERE YET? ASTHMA IS THE MOST COMMON NON-COMMUNICABLE CHRONIC DISEASE OF CHILDHOOD. DESPITE ITS HIGH PREVALENCE, TO DATE WE LACK METHODS THAT ARE BOTH EFFICIENT AND ACCURATE IN DIAGNOSING ASTHMA. MOST TRADITIONAL APPROACHES HAVE BEEN BASED ON GARNERING CLINICAL EVIDENCE, SUCH AS RISK FACTORS AND EXPOSURES. GIVEN THE HIGH HERITABILITY OF ASTHMA, MORE RECENT APPROACHES HAVE LOOKED AT GENETIC POLYMORPHISMS AS POTENTIAL "RISK FACTORS." HOWEVER, GENETIC VARIANTS EXPLAIN ONLY A SMALL PROPORTION OF ASTHMA RISK, AND HAVE BEEN LESS THAN OPTIMAL AT PREDICTING RISK FOR INDIVIDUAL SUBJECTS. EPIGENOMIC STUDIES OFFER SIGNIFICANT ADVANTAGES OVER PREVIOUS APPROACHES. EPIGENETIC REGULATION IS HIGHLY TISSUE-SPECIFIC, AND CAN INDUCE BOTH SHORT- AND LONG-TERM CHANGES IN GENE EXPRESSION. SUCH CHANGES CAN START IN UTERO, CAN VARY THROUGHOUT THE LIFE SPAN, AND IN SOME INSTANCES CAN BE PASSED ON FROM ONE GENERATION TO ANOTHER. MOST IMPORTANTLY, THE EPIGENOME CAN BE MODIFIED BY ENVIRONMENTAL FACTORS AND EXPOSURES, AND THUS EPIGENETIC AND TRANSCRIPTOMIC PROFILING MAY YIELD THE MOST ACCURATE RISK ESTIMATES FOR A GIVEN PATIENT BY INCORPORATING ENVIRONMENTAL (AND TREATMENT) EFFECTS THROUGHOUT THE LIFESPAN. HERE WE WILL REVIEW THE MOST RECENT ADVANCES IN THE USE OF EPIGENETIC AND TRANSCRIPTOMIC ANALYSIS FOR THE EARLY DIAGNOSIS OF ASTHMA AND ATOPY, AS WELL AS CHALLENGES AND FUTURE DIRECTIONS IN THE FIELD AS IT MOVES FORWARD. WE WILL PARTICULARLY FOCUS ON DNA METHYLATION, THE MOST STUDIED MECHANISM OF EPIGENETIC REGULATION. 2019