1 2531 86 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 2 5552 36 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 2330 40 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 4 2160 29 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 5 2492 30 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 6 6735 30 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 3028 25 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 8 396 30 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 9 1546 32 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 10 2530 37 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 11 2497 21 EPIGENETICS AND ENVIRONMENTAL LUNG DISEASE. GENE-ENVIRONMENT INTERACTIONS ARE THE INDISPUTABLE CAUSE OF MOST RESPIRATORY DISEASES. HOWEVER, WE STILL HAVE VERY LIMITED UNDERSTANDING OF THE MECHANISMS THAT GUIDE THESE INTERACTIONS. ALTHOUGH THE CONCEPTUAL APPROACHES TO ENVIRONMENTAL GENOMICS WERE ESTABLISHED SEVERAL DECADES AGO, THE TOOLS ARE ONLY NOW AVAILABLE TO BETTER DEFINE THE MECHANISMS THAT UNDERLIE THE INTERACTION BETWEEN THESE IMPORTANT ETIOLOGIC FEATURES OF LUNG DISEASE. EPIGENETIC MECHANISMS CAN MEDIATE THE EFFECT OF THE ENVIRONMENT ON THE HUMAN GENOME BY CONTROLLING THE TRANSCRIPTIONAL ACTIVITY OF SPECIFIC GENES, AT SPECIFIC POINTS IN TIME, IN SPECIFIC ORGANS. IN THIS ARTICLE, WE DEMONSTRATE THE POTENTIAL IMPORTANCE OF EPIGENETIC MECHANISMS IN THE DEVELOPMENT AND PROGRESSION OF CHRONIC OBSTRUCTIVE PULMONARY DISEASE AND ASTHMA. 2010 12 2519 42 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 13 6811 35 [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 14 1640 28 DOES EPIGENETICS PLAY A ROLE IN HUMAN ASTHMA? ASTHMA AND OTHER ALLERGIC DISEASES ARE AMONG THE MOST PREVALENT CHRONIC NON-COMMUNICABLE DISEASES OF CHILDHOOD. ACCORDING TO THE WORLD HEALTH ORGANIZATION, ASTHMA AFFECTS >7.0 MILLION CHILDREN UNDER 18 IN THE UNITED STATES, WITH AN ECONOMIC BURDEN THAT IS ESTIMATED TO EXCEED THAT OF TUBERCULOSIS AND HIV/AIDS COMBINED. DESPITE MUCH RESEARCH, THE NATURAL HISTORY OF ASTHMA AND ITS PATHOGENESIS ARE STILL IN MANY WAYS ELUSIVE. THIS REVIEW DISCUSSES OUR CURRENT UNDERSTANDING OF THE ROLE EPIGENETIC PROCESSES PLAY IN ASTHMA PATHOGENESIS, FOCUSING ON GENOME-WIDE, POPULATION-BASED STUDIES. 2016 15 3421 33 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 16 2984 29 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 17 2651 32 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 18 528 30 ASTHMA EPIGENETICS. ASTHMA IS THE MOST COMMON CHRONIC DISEASE OF CHILDHOOD, AND A GROWING BODY OF EVIDENCE INDICATES THAT EPIGENETIC VARIATIONS MAY MEDIATE THE EFFECTS OF ENVIRONMENTAL EXPOSURES ON THE DEVELOPMENT AND NATURAL HISTORY OF ASTHMA. EPIGENETICS IS THE STUDY OF MITOTICALLY OR MEIOTICALLY HERITABLE CHANGES IN GENE EXPRESSION THAT OCCUR WITHOUT DIRECTLY ALTERING THE DNA SEQUENCE. DNA METHYLATION, HISTONE MODIFICATIONS AND MICRORNAS ARE MAJOR EPIGENETIC VARIATIONS IN HUMANS THAT ARE CURRENTLY BEING INVESTIGATED FOR ASTHMA ETIOLOGY AND NATURAL HISTORY. DNA METHYLATION RESULTS FROM ADDITION OF A METHYL GROUP TO THE 5 POSITION OF A CYTOSINE RING AND OCCURS ALMOST EXCLUSIVELY ON A CYTOSINE IN A CPG DINUCLEOTIDE. HISTONE MODIFICATIONS INVOLVE POSTTRANSLATIONAL MODIFICATIONS SUCH AS ACETYLATION, METHYLATION, PHOSPHORYLATION AND UBIQUITINATION ON THE TAILS OF CORE HISTONES. MICRORNAS ARE SHORT ~22 NUCLEOTIDE LONG, NON-CODING, SINGLE-STRANDED RNAS THAT BINDS TO COMPLEMENTARY SEQUENCES IN THE TARGET MRNAS, USUALLY RESULTING IN GENE SILENCING. WHILE MANY STUDIES HAVE DOCUMENTED RELATIONSHIPS OF ENVIRONMENTAL EXPOSURES THAT HAVE BEEN IMPLICATED IN ASTHMA ETIOLOGY WITH EPIGENETIC ALTERATIONS, TO DATE, FEW STUDIES HAVE DIRECTLY LINKED EPIGENETIC VARIATIONS WITH ASTHMA DEVELOPMENT. THERE ARE SEVERAL METHODOLOGICAL CHALLENGES IN STUDYING THE EPIGENETICS OF ASTHMA. IN THIS CHAPTER, THE INFLUENCE OF EPIGENETIC VARIATIONS ON ASTHMA PATHOPHYSIOLOGY, METHODOLOGICAL CONCERNS IN CONDUCTING EPIGENETIC RESEARCH AND FUTURE DIRECTION OF ASTHMA EPIGENETICS RESEARCH ARE DISCUSSED. 2014 19 1290 29 DECODING THE GENETIC AND EPIGENETIC BASIS OF ASTHMA. ASTHMA IS A COMPLEX AND HETEROGENEOUS CHRONIC INFLAMMATORY DISEASE OF THE AIRWAYS. ALONGSIDE ENVIRONMENTAL FACTORS, ASTHMA SUSCEPTIBILITY IS STRONGLY INFLUENCED BY GENETICS. GIVEN ITS HIGH PREVALENCE AND OUR INCOMPLETE UNDERSTANDING OF THE MECHANISMS UNDERLYING DISEASE SUSCEPTIBILITY, ASTHMA IS FREQUENTLY STUDIED IN GENOME-WIDE ASSOCIATION STUDIES (GWAS), WHICH HAVE IDENTIFIED THOUSANDS OF GENETIC VARIANTS ASSOCIATED WITH ASTHMA DEVELOPMENT. VIRTUALLY ALL THESE GENETIC VARIANTS RESIDE IN NON-CODING GENOMIC REGIONS, WHICH HAS OBSCURED THE FUNCTIONAL IMPACT OF ASTHMA-ASSOCIATED VARIANTS AND THEIR TRANSLATION INTO DISEASE-RELEVANT MECHANISMS. RECENT ADVANCES IN GENOMICS TECHNOLOGY AND EPIGENETICS NOW OFFER METHODS TO LINK GENETIC VARIANTS TO GENE REGULATORY ELEMENTS EMBEDDED WITHIN NON-CODING REGIONS, WHICH HAVE STARTED TO UNRAVEL THE MOLECULAR MECHANISMS UNDERLYING THE COMPLEX (EPI)GENETICS OF ASTHMA. HERE, WE PROVIDE AN INTEGRATED OVERVIEW OF (EPI)GENETIC VARIANTS ASSOCIATED WITH ASTHMA, FOCUSING ON EFFORTS TO LINK THESE DISEASE ASSOCIATIONS TO BIOLOGICAL INSIGHT INTO ASTHMA PATHOPHYSIOLOGY USING STATE-OF-THE-ART GENOMICS METHODOLOGY. FINALLY, WE PROVIDE A PERSPECTIVE AS TO HOW DECODING THE GENETIC AND EPIGENETIC BASIS OF ASTHMA HAS THE POTENTIAL TO TRANSFORM CLINICAL MANAGEMENT OF ASTHMA AND TO PREDICT THE RISK OF ASTHMA DEVELOPMENT. 2023 20 6303 40 THE PUZZLE OF IMMUNE PHENOTYPES OF CHILDHOOD ASTHMA. ASTHMA REPRESENTS THE MOST COMMON CHRONIC CHILDHOOD DISEASE WORLDWIDE. WHEREAS PRESCHOOL CHILDREN PRESENT WITH WHEEZING TRIGGERED BY DIFFERENT FACTORS (MULTITRIGGER AND VIRAL WHEEZE), CLINICAL ASTHMA MANIFESTATION IN SCHOOL CHILDREN HAS PREVIOUSLY BEEN CLASSIFIED AS ALLERGIC AND NON-ALLERGIC ASTHMA. FOR BOTH, THE UNDERLYING IMMUNOLOGICAL MECHANISMS ARE NOT YET UNDERSTOOD IN DEPTH IN CHILDREN. TREATMENT IS STILL PRESCRIBED REGARDLESS OF UNDERLYING MECHANISMS, AND CHILDREN ARE NOT ALWAYS TREATED SUCCESSFULLY. THIS REVIEW SUMMARIZES RECENT KEY FINDINGS ON THE COMPLEX MECHANISMS OF THE DEVELOPMENT AND MANIFESTATION OF CHILDHOOD ASTHMA. WHEREAS TRADITIONAL CLASSIFICATION OF CHILDHOOD ASTHMA IS PRIMARILY BASED ON CLINICAL SYMPTOMS LIKE WHEEZING AND ATOPY, NOVEL APPROACHES TO SPECIFY ASTHMA PHENOTYPES ARE UNDER WAY AND FACE CHALLENGES SUCH AS INCLUDING THE STABILITY OF PHENOTYPES OVER TIME AND TRANSITION INTO ADULTHOOD. EPIDEMIOLOGICAL STUDIES ENCLOSE MORE INFORMATION ON THE PATIENT'S DISEASE HISTORY AND ENVIRONMENTAL INFLUENCES. LATEST STUDIES DEFINE ENDOTYPES BASED ON MOLECULAR AND CELLULAR MECHANISMS, FOR EXAMPLE DEFINING RISK AND PROTECTIVE SINGLE NUCLEOTIDE POLYMORPHISMS (SNPS) AND NEW IMMUNE PHENOTYPES, SHOWING PROMISING RESULTS. ALSO, REGULATORY T CELLS AND RECENTLY DISCOVERED T HELPER CELL SUBTYPES SUCH AS TH9 AND TH17 CELLS WERE SHOWN TO BE IMPORTANT FOR THE DEVELOPMENT OF ASTHMA. INNATE LYMPHOID CELLS (ILC) COULD PLAY A CRITICAL ROLE IN ASTHMA PATIENTS AS THEY PRODUCE DIFFERENT CYTOKINES ASSOCIATED WITH ASTHMA. EPIGENETIC FINDINGS SHOWED DIFFERENT ACETYLATION AND METHYLATION PATTERNS FOR CHILDREN WITH ALLERGIC AND NON-ALLERGIC ASTHMA. ON A POSTTRANSCRIPTIONAL LEVEL, MIRNAS ARE REGULATING FACTORS IDENTIFIED TO DIFFER BETWEEN ASTHMA PATIENTS AND HEALTHY CONTROLS AND ALSO INDICATE DIFFERENCES WITHIN ASTHMA PHENOTYPES. METABOLOMICS IS ANOTHER EXCITING CHAPTER IMPORTANT FOR ENDOTYPING ASTHMATIC CHILDREN. DESPITE THE DEVELOPMENT OF NEW BIOMARKERS AND THE DISCOVERY OF NEW IMMUNOLOGICAL MOLECULES, THE COMPLEX PUZZLE OF CHILDHOOD ASTHMA IS STILL FAR FROM BEING COMPLETED. ADDRESSING THE CURRENT CHALLENGES OF DISTINCT CLINICAL ASTHMA AND WHEEZE PHENOTYPES, INCLUDING THEIR STABILITY AND UNDERLYING ENDOTYPES, INVOLVES ADDRESSING THE INTERPLAY OF INNATE AND ADAPTIVE IMMUNE REGULATORY MECHANISMS IN LARGE, INTERDISCIPLINARY COHORTS. 2016