1 3698 100 INFLAMMATORY MECHANISMS LINKING MATERNAL AND CHILDHOOD ASTHMA. ASTHMA IS A CHRONIC INFLAMMATORY AIRWAY DISEASE CHARACTERIZED BY AIRWAY HYPERRESPONSIVENESS, INFLAMMATION, AND REMODELING. ASTHMA OFTEN DEVELOPS DURING CHILDHOOD AND CAUSES LIFELONG DECREMENTS IN LUNG FUNCTION AND QUALITY OF LIFE. RISK FACTORS FOR CHILDHOOD ASTHMA ARE NUMEROUS AND INCLUDE GENETIC, EPIGENETIC, DEVELOPMENTAL, AND ENVIRONMENTAL FACTORS. UNCONTROLLED MATERNAL ASTHMA DURING PREGNANCY EXPOSES THE DEVELOPING FETUS TO INFLAMMATORY INSULTS, WHICH FURTHER INCREASE THE RISK OF CHILDHOOD ASTHMA INDEPENDENT OF GENETIC PREDISPOSITION. THIS REVIEW FOCUSES ON THE ROLE OF MATERNAL ASTHMA IN THE DEVELOPMENT OF ASTHMA IN OFFSPRING. WE WILL PRESENT MATERNAL ASTHMA AS A TARGETABLE AND MODIFIABLE RISK FACTOR FOR CHILDHOOD ASTHMA AND DISCUSS THE MECHANISMS BY WHICH MATERNAL INFLAMMATION INCREASES CHILDHOOD ASTHMA RISK. TOPICS INCLUDE HOW EXPOSURE TO MATERNAL ASTHMA IN UTERO SHAPES STRUCTURAL LUNG DEVELOPMENT WITH A SPECIAL EMPHASIS ON AIRWAY NERVES, HOW MATERNAL TYPE-2 CYTOKINES SUCH AS IL-5 ACTIVATE THE FETAL IMMUNE SYSTEM, AND HOW CHANGES IN LUNG AND IMMUNE CELL DEVELOPMENT INFORM RESPONSES TO AERO-ALLERGENS LATER IN LIFE. FINALLY, WE HIGHLIGHT EMERGING EVIDENCE THAT MATERNAL ASTHMA ESTABLISHES A UNIQUE "ASTHMA SIGNATURE" IN THE AIRWAYS OF CHILDREN, LEADING TO NOVEL MECHANISMS OF AIRWAY HYPERREACTIVITY AND INFLAMMATORY CELL RESPONSES. 2020 2 6808 21 [EPIGENETICS IN ALLERGIC DISEASES AND ASTHMA]. ALLERGIC DISEASES AND ASTHMA ARE THE RESULT OF COMPLEX INTERACTIONS BETWEEN GENETIC PREDISPOSITION AND ENVIRONMENTAL FACTORS. ASTHMA IS ONE OF THE MOST PREVALENT CHRONIC DISEASE AMONG CHILDREN. IN THIS ARTICLE WE REVIEW SOME ENVIRONMENTAL FACTORS LIKE: ALLERGEN EXPOSITION, TOBACCO, BACTERIA, MICROBIAL COMPONENTS, DIET, OBESITY AND STRESS, WHICH INFLUENCES DURING INTRAUTERINE AND INFANCY LIFE IN THE EPIGENETIC REGULATION OF ASTHMA AND ALLERGIC DISEASES. THE REVIEW HAS BEEN DONE IN THREE MODELS: IN-VITRO, ANIMAL AND HUMAN. 2016 3 2531 28 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 4 1760 29 EARLY PREDICTORS OF ASTHMA AND ALLERGY IN CHILDREN: THE ROLE OF EPIGENETICS. PURPOSE OF REVIEW: ASTHMA AND ALLERGIC DISEASES ARE AMONG THE MOST PREVALENT CHRONIC NONCOMMUNICABLE DISEASES OF CHILDHOOD. ALTHOUGH EPIDEMIOLOGIC STUDIES SUGGEST THAT ASTHMA BEGINS IN THE PRESCHOOL YEARS, THE LACK OF FIRM DIAGNOSTIC CRITERIA TO DISTINGUISH CHILDREN WHO WILL WHEEZE ONLY TRANSIENTLY DURING EARLY-LIFE LOWER RESPIRATORY ILLNESSES FROM CHILDREN WHO WILL WHEEZE PERSISTENTLY AND DEVELOP ASTHMA PREVENTS PINPOINTING THE TIME AT WHICH DISEASE TRULY BEGINS. EPIGENETIC MECHANISMS LINK GENE REGULATION TO ENVIRONMENTAL CUES AND DEVELOPMENTAL TRAJECTORIES. THIS ARTICLE REVIEWS, THE SEARCH FOR EPIGENETIC PREDICTORS OF ASTHMA AND/OR ALLERGY THAT CAN BE IDENTIFIED ALREADY AT BIRTH AND/OR IN EARLY LIFE. RECENT FINDINGS: DNA METHYLATION SIGNATURES ASSOCIATED WITH ASTHMA AND/OR ALLERGY AT BIRTH, AND TIME-DEPENDENT DNA METHYLATION SIGNATURES ASSOCIATED WITH ALLERGIC DISEASE PHENOTYPES IN EARLY LIFE HAVE BEEN IDENTIFIED. SUMMARY: THE IDENTIFICATION OF EARLY EPIGENETIC PREDICTORS OF ALLERGIC DISEASES POINTS TO A POTENTIAL ROLE OF EPIGENETIC MECHANISMS IN REGULATING THE INCEPTION OF AND THE SUSCEPTIBILITY TO THESE DISEASES. PREDICTIVE SIGNATURES TO MORE ACCURATELY ESTIMATE A CHILD'S RISK FOR ASTHMA AND ALLERGY MAY IMPROVE CHILDHOOD ASTHMA DIAGNOSIS. MOREOVER, UNDERSTANDING THE BIOLOGICAL IMPLICATIONS OF THESE SIGNATURES MAY HELP ELUCIDATE NOVEL DISEASE PATHWAYS AND ENDOTYPES. 2015 5 529 30 ASTHMA IN URBAN CHILDREN: EPIDEMIOLOGY, ENVIRONMENTAL RISK FACTORS, AND THE PUBLIC HEALTH DOMAIN. ASTHMA IS THE MOST COMMONLY REPORTED CHRONIC CONDITION OF CHILDHOOD IN DEVELOPED COUNTRIES, WITH 6.5 MILLION CHILDREN AFFECTED IN THE USA. A DISPARATE BURDEN OF CHILDHOOD ASTHMA IS SEEN AMONG SOCIOECONOMICALLY DISADVANTAGED YOUTH, OFTEN CONCENTRATED IN URBAN AREAS WITH HIGH POVERTY RATES. HOST FACTORS THAT PREDISPOSE A CHILD TO ASTHMA INCLUDE ATOPY, MALE GENDER, PARENTAL HISTORY OF ASTHMA, AND ALSO RACE, ETHNICITY, AND GENETIC AND EPIGENETIC SUSCEPTIBILITIES. ENVIRONMENTAL FACTORS, SUCH AS IMPROVED HYGIENE, AMBIENT AIR POLLUTION, AND EARLY LIFE EXPOSURES TO MICROBES AND AEROALLERGENS, ALSO INFLUENCE THE DEVELOPMENT OF ASTHMA. WITH GREATER THAN 90% OF TIME SPENT INDOORS, HOME EXPOSURES (SUCH AS COCKROACH, RODENT, AND INDOOR AIR POLLUTION) ARE HIGHLY RELEVANT FOR URBAN ASTHMA. MORBIDITY REDUCTION MAY REQUIRE FOCUSED PUBLIC HEALTH INITIATIVES FOR ENVIRONMENTAL INTERVENTION IN HIGH PRIORITY RISK GROUPS AND THE ADDITION OF IMMUNE MODULATORY AGENTS IN CHILDREN WITH POORLY CONTROLLED DISEASE. 2016 6 6915 26 [VULNERABILITY OF WOMEN TO TOBACCO: THE BRONCHO-PULMONARY CONSEQUENCES (ASTHMA, COPD)]. SMOKING REMAINS COMMON, WITH AN EXPOSURE THAT BEGINS EARLY DURING PREGNANCY. IT INDUCES EPIGENETIC CHANGES, WITH A TRANS-GENERATIONAL TRANSMISSION. SMOKING INCREASES THE RISK OF UNCONTROLLED ASTHMA DURING CHILDHOOD AND ADULT LIFE. ASTHMA IS ALSO ASSOCIATED WITH INCREASED RISK OF A DECLINE OF LUNG FUNCTION AND CHRONIC OBSTRUCTIVE PULMONARY DISEASE (COPD). WOMEN ARE MORE AT RISK OF DEVELOPING EARLY AND SEVERE COPD. THE MECHANISMS ARE CURRENTLY POORLY KNOWN. 2019 7 6303 33 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 8 5552 35 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 9 2160 23 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 10 1640 19 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 11 1290 28 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 12 530 36 ASTHMA. ASTHMA IS THE MOST COMMON INFLAMMATORY DISEASE OF THE LUNGS. THE PREVALENCE OF ASTHMA IS INCREASING IN MANY PARTS OF THE WORLD THAT HAVE ADOPTED ASPECTS OF THE WESTERN LIFESTYLE, AND THE DISEASE POSES A SUBSTANTIAL GLOBAL HEALTH AND ECONOMIC BURDEN. ASTHMA INVOLVES BOTH THE LARGE-CONDUCTING AND THE SMALL-CONDUCTING AIRWAYS, AND IS CHARACTERIZED BY A COMBINATION OF INFLAMMATION AND STRUCTURAL REMODELLING THAT MIGHT BEGIN IN UTERO. DISEASE PROGRESSION OCCURS IN THE CONTEXT OF A DEVELOPMENTAL BACKGROUND IN WHICH THE POSTNATAL ACQUISITION OF ASTHMA IS STRONGLY LINKED WITH ALLERGIC SENSITIZATION. MOST ASTHMA CASES FOLLOW A VARIABLE COURSE, INVOLVING VIRAL-INDUCED WHEEZING AND ALLERGEN SENSITIZATION, THAT IS ASSOCIATED WITH VARIOUS UNDERLYING MECHANISMS (OR ENDOTYPES) THAT CAN DIFFER BETWEEN INDIVIDUALS. EACH SET OF ENDOTYPES, IN TURN, PRODUCES SPECIFIC ASTHMA CHARACTERISTICS THAT EVOLVE ACROSS THE LIFECOURSE OF THE PATIENT. STRONG GENETIC AND ENVIRONMENTAL DRIVERS OF ASTHMA INTERCONNECT THROUGH NOVEL EPIGENETIC MECHANISMS THAT OPERATE PRENATALLY AND THROUGHOUT CHILDHOOD. ASTHMA CAN SPONTANEOUSLY REMIT OR BEGIN DE NOVO IN ADULTHOOD, AND THE FACTORS THAT LEAD TO THE EMERGENCE AND REGRESSION OF ASTHMA, IRRESPECTIVE OF AGE, ARE POORLY UNDERSTOOD. NONETHELESS, THERE IS MOUNTING EVIDENCE THAT SUPPORTS A PRIMARY ROLE FOR STRUCTURAL CHANGES IN THE AIRWAYS WITH ASTHMA ACQUISITION, ON WHICH ALTERED INNATE IMMUNE MECHANISMS AND MICROBIOTA INTERACTIONS ARE SUPERIMPOSED. ON THE BASIS OF THE IDENTIFICATION OF NEW CAUSATIVE PATHWAYS, THE SUBPHENOTYPING OF ASTHMA ACROSS THE LIFECOURSE OF PATIENTS IS PAVING THE WAY FOR MORE-PERSONALIZED AND PRECISE PATHWAY-SPECIFIC APPROACHES FOR THE PREVENTION AND TREATMENT OF ASTHMA, CREATING THE REAL POSSIBILITY OF TOTAL PREVENTION AND CURE FOR THIS CHRONIC INFLAMMATORY DISEASE. 2015 13 2519 35 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 14 305 31 AIRWAY WALL REMODELING IN CHILDHOOD ASTHMA-A PERSONALIZED PERSPECTIVE FROM CELL TYPE-SPECIFIC BIOLOGY. AIRWAY WALL REMODELING IS A PATHOLOGY OCCURRING IN CHRONIC INFLAMMATORY LUNG DISEASES INCLUDING ASTHMA, CHRONIC OBSTRUCTIVE PULMONARY DISEASE, AND FIBROSIS. IN 2017, THE AMERICAN THORACIC SOCIETY RELEASED A RESEARCH STATEMENT HIGHLIGHTING THE GAPS IN KNOWLEDGE AND UNDERSTANDING OF AIRWAY WALL REMODELING. THE FOUR MAJOR CHALLENGES ADDRESSED IN THIS STATEMENT WERE: (I) THE LACK OF CONSENSUS TO DEFINE "AIRWAY WALL REMODELING" IN DIFFERENT DISEASES, (II) METHODOLOGIC LIMITATIONS AND INAPPROPRIATE MODELS, (III) THE LACK OF ANTI-REMODELING THERAPIES, AND (IV) THE DIFFICULTY TO DEFINE ENDPOINTS AND OUTCOMES IN RELEVANT STUDIES. THIS REVIEW FOCUSES ON THE IMPORTANCE OF CELL-CELL INTERACTION, ESPECIALLY THE BRONCHIAL EPITHELIUM, IN ASTHMA-ASSOCIATED AIRWAY WALL REMODELING. THE PATHOLOGY OF "AIRWAY WALL REMODELING" SUMMARIZES ALL STRUCTURAL CHANGES OF THE AIRWAY WALL WITHOUT DIFFERENTIATING BETWEEN DIFFERENT PHENO- OR ENDO-TYPES OF ASTHMA. INDICATORS OF AIRWAY WALL REMODELING HAVE BEEN REPORTED IN CHILDHOOD ASTHMA IN THE ABSENCE OF ANY SIGN OF INFLAMMATION; THUS, THE INITIATION EVENT REMAINS UNKNOWN. RECENT STUDIES HAVE IMPLIED THAT THE INTERACTION BETWEEN THE EPITHELIUM WITH IMMUNE CELLS AND SUB-EPITHELIAL MESENCHYMAL CELLS IS MODIFIED IN ASTHMA BY A YET UNKNOWN EPIGENETIC MECHANISM DURING EARLY CHILDHOOD. 2021 15 602 36 BETTER UNDERSTANDING OF CHILDHOOD ASTHMA, TOWARDS PRIMARY PREVENTION - ARE WE THERE YET? CONSIDERATION OF PERTINENT LITERATURE. ASTHMA IS A CHRONIC DISEASE, CHARACTERIZED BY REVERSIBLE AIRWAY OBSTRUCTION, AIRWAY INFLAMMATION AND HYPER-REACTIVITY. THE PREVALENCE OF ASTHMA HAS RISEN DRAMATICALLY OVER THE PAST DECADE, AFFECTING AROUND 300,000,000 PEOPLE. THE ETIOLOGY IS MULTIFACTORIAL, WITH GENETIC, EPIGENETIC, DEVELOPMENTAL AND ENVIRONMENTAL FACTORS PLAYING A ROLE. A COMPLEX INTERACTION BETWEEN THE INTRAUTERINE ENVIRONMENT, THE DEVELOPING IMMUNE SYSTEM, THE INFANT'S MICROBIOME AND INFECTIOUS ORGANISMS MAY LEAD TO THE DEVELOPMENT OF ALLERGIC SENSITIZATION AND ASTHMA. THUS, A LARGE NUMBER OF STUDIES HAVE INVESTIGATED THE RISK FACTORS FOR CHILDHOOD ASTHMA, WITH A METICULOUS SEARCH OF MODIFIABLE FACTORS THAT COULD AID IN PRIMARY PREVENTION. WE PRESENT A CURRENT LITERATURE REVIEW FROM 2014-2017, AS WELL AS OLDER CLASSIC PUBLICATIONS, ON THE PATHOGENESIS AND THE POTENTIAL MODIFIABLE FACTORS FOR PRIMARY PREVENTION OF ASTHMA. NO IDEAL PREVENTIVE MEASURE HAS YET BEEN FOUND. RATHER, CREATING FAVORABLE PRENATAL AND POSTNATAL ENVIRONMENTS, MINIMAL EXPOSURE TO HOSTILE ENVIRONMENTAL FACTORS, PREVENTION OF INFECTIONS IN EARLY LIFE, ALLERGIC DESENSITIZATION AND NUTRITIONAL MODIFICATIONS COULD POSSIBLY REDUCE ASTHMA INCEPTION. IN THE ERA OF PERSONALIZED MEDICINE, IDENTIFYING INDIVIDUAL RISK FACTORS AND TAILORING SPECIFIC PREVENTIVE MEASURES IS WARRANTED. 2017 16 6005 34 THE AIRWAY EPITHELIUM-A CENTRAL PLAYER IN ASTHMA PATHOGENESIS. ASTHMA IS A CHRONIC INFLAMMATORY AIRWAY DISEASE CHARACTERIZED BY VARIABLE AIRFLOW OBSTRUCTION IN RESPONSE TO A WIDE RANGE OF EXOGENOUS STIMULI. THE AIRWAY EPITHELIUM IS THE FIRST LINE OF DEFENSE AND PLAYS AN IMPORTANT ROLE IN INITIATING HOST DEFENSE AND CONTROLLING IMMUNE RESPONSES. INDEED, INCREASING EVIDENCE INDICATES A RANGE OF ABNORMALITIES IN VARIOUS ASPECTS OF EPITHELIAL BARRIER FUNCTION IN ASTHMA. A CENTRAL PART OF THIS IMPAIRMENT IS A DISRUPTION OF THE AIRWAY EPITHELIAL LAYER, ALLOWING INHALED SUBSTANCES TO PASS MORE EASILY INTO THE SUBMUCOSA WHERE THEY MAY INTERACT WITH IMMUNE CELLS. FURTHERMORE, MANY OF THE IDENTIFIED SUSCEPTIBILITY GENES FOR ASTHMA ARE EXPRESSED IN THE AIRWAY EPITHELIUM. THIS REVIEW FOCUSES ON THE BIOLOGY OF THE AIRWAY EPITHELIUM IN HEALTH AND ITS PATHOBIOLOGY IN ASTHMA. WE WILL SPECIFICALLY DISCUSS EXTERNAL TRIGGERS SUCH AS ALLERGENS, VIRUSES AND ALARMINS AND THE EFFECT OF TYPE 2 INFLAMMATORY RESPONSES ON AIRWAY EPITHELIAL FUNCTION IN ASTHMA. WE WILL ALSO DISCUSS EPIGENETIC MECHANISMS RESPONDING TO EXTERNAL STIMULI ON THE LEVEL OF TRANSCRIPTIONAL AND POSTTRANSCRIPTIONAL REGULATION OF GENE EXPRESSION, AS WELL THE AIRWAY EPITHELIUM AS A POTENTIAL TREATMENT TARGET IN ASTHMA. 2020 17 1757 25 EARLY ORIGINS OF ASTHMA (AND ALLERGY). ASTHMA IS THE MOST COMMON CHRONIC DISEASE STARTING IN CHILDHOOD AND PERSISTING INTO ADULTHOOD IN MANY CASES. DURING CHILDHOOD, DIFFERENT FORMS OF ASTHMA AND WHEEZING DISORDERS EXIST THAT CAN BE DISCRIMINATED BY THE MECHANISMS THEY ARE CAUSED BY. SPECIFIC GENETIC CONSTELLATIONS AND EXPOSURE AGAINST ENVIRONMENTAL FACTORS DURING EARLY CHILDHOOD AND IN UTERO PLAY A DECISIVE ROLE IN THE EARLY DEVELOPMENT OF THE DISEASE. EPIGENETIC MECHANISMS WHICH ARE MASTER REGULATORS OF GENE TRANSCRIPTION AND THUS GOVERN THE ACCESSIBILITY AND USE OF GENOME INFORMATION, HAVE RECENTLY BEEN IDENTIFIED AS A "THIRD POWER" DETERMINING MANY FEATURES IN THE EARLY DEVELOPMENT OF ASTHMA AND ALLERGY. 2016 18 298 38 AIR POLLUTION AND AIRWAY DISEASE. EPIDEMIOLOGICAL AND TOXICOLOGICAL RESEARCH CONTINUES TO SUPPORT A LINK BETWEEN URBAN AIR POLLUTION AND AN INCREASED INCIDENCE AND/OR SEVERITY OF AIRWAY DISEASE. DETRIMENTAL EFFECTS OF OZONE (O(3)), NITROGEN DIOXIDE (NO(2)) AND PARTICULATE MATTER (PM), AS WELL AS TRAFFIC-RELATED POLLUTION AS A WHOLE, ON RESPIRATORY SYMPTOMS AND FUNCTION ARE WELL DOCUMENTED. NOT ONLY DO WE HAVE STRONG EPIDEMIOLOGICAL EVIDENCE OF A RELATIONSHIP BETWEEN AIR POLLUTION AND EXACERBATION OF ASTHMA AND RESPIRATORY MORBIDITY AND MORTALITY IN PATIENTS WITH CHRONIC OBSTRUCTIVE PULMONARY DISEASE (COPD), BUT RECENT STUDIES, PARTICULARLY IN URBAN AREAS, HAVE SUGGESTED A ROLE FOR POLLUTANTS IN THE DEVELOPMENT OF BOTH ASTHMA AND COPD. SIMILARLY, WHILE PREVALENCE AND SEVERITY OF ATOPIC CONDITIONS APPEAR TO BE MORE COMMON IN URBAN COMPARED WITH RURAL COMMUNITIES, EVIDENCE IS EMERGING THAT TRAFFIC-RELATED POLLUTANTS MAY CONTRIBUTE TO THE DEVELOPMENT OF ALLERGY. FURTHERMORE, NUMEROUS EPIDEMIOLOGICAL AND EXPERIMENTAL STUDIES SUGGEST AN ASSOCIATION BETWEEN EXPOSURE TO NO(2) , O(3) , PM AND COMBUSTION PRODUCTS OF BIOMASS FUELS AND AN INCREASED SUSCEPTIBILITY TO AND MORBIDITY FROM RESPIRATORY INFECTION. GIVEN THE CONSIDERABLE CONTRIBUTION THAT TRAFFIC EMISSIONS MAKE TO URBAN AIR POLLUTION RESEARCHERS HAVE SOUGHT TO CHARACTERIZE THE RELATIVE TOXICITY OF TRAFFIC-RELATED PM POLLUTANTS. RECENT ADVANCES IN MECHANISMS IMPLICATED IN THE ASSOCIATION OF AIR POLLUTANTS AND AIRWAY DISEASE INCLUDE EPIGENETIC ALTERATION OF GENES BY COMBUSTION-RELATED POLLUTANTS AND HOW POLYMORPHISMS IN GENES INVOLVED IN ANTIOXIDANT PATHWAYS AND AIRWAY INFLAMMATION CAN MODIFY RESPONSES TO AIR POLLUTION EXPOSURES. OTHER INTERESTING EPIDEMIOLOGICAL OBSERVATIONS RELATED TO INCREASED HOST SUSCEPTIBILITY INCLUDE A POSSIBLE LINK BETWEEN CHRONIC PM EXPOSURE DURING CHILDHOOD AND VULNERABILITY TO COPD IN ADULTHOOD, AND THAT INFANTS SUBJECTED TO HIGHER PRENATAL LEVELS OF AIR POLLUTION MAY BE AT GREATER RISK OF DEVELOPING RESPIRATORY CONDITIONS. WHILE THE CHARACTERIZATION OF POLLUTANT COMPONENTS AND SOURCES PROMISE TO GUIDE POLLUTION CONTROL STRATEGIES, THE IDENTIFICATION OF SUSCEPTIBLE SUBPOPULATIONS WILL BE NECESSARY IF TARGETED THERAPY/PREVENTION OF POLLUTION-INDUCED RESPIRATORY DISEASES IS TO BE DEVELOPED. 2011 19 2138 29 EPIGENETIC INHERITANCE OF FETAL GENES IN ALLERGIC ASTHMA. ASTHMA HAS BEEN ASSOCIATED WITH AN EXAGGERATED T-HELPER TYPE 2 (TH2) OVER TH1 RESPONSES TO ALLERGIC AND NONALLERGIC STIMULI, WHICH LEADS TO CHRONIC AIRWAY INFLAMMATION AND AIRWAY REMODELING. IN THE PRESENT ARTICLE, WE PROPOSE THAT MANY OF THE GENES INVOLVED IN IGE SYNTHESIS AND AIRWAYS (RE)MODELING IN ASTHMA ARE PERSISTENT OR REMINISCENT FETAL GENES WHICH MAY NOT BE SILENCED DURING EARLY INFANCY (OR LATE PREGNANCY). GENES OF THE EMBRYOLOGIC DIFFERENTIATION OF ECTODERMIC AND ENDODERMIC TISSUES MAY EXPLAIN SOME OF THE PATTERNS OF AIRWAY REMODELING IN ASTHMA. IN UTERO PROGRAMMING LEADS TO GENE EXPRESSION, THE PERSISTENCE OF WHICH MAY BE ASSOCIATED WITH EPIGENETIC INHERITANCE PHENOMENA INDUCED BY NONSPECIFIC ENVIRONMENTAL FACTORS. CLEAR DELINEATION OF THESE ISSUES MAY YIELD NEW INFORMATION ON THE MECHANISMS OF ASTHMA AND NEW TARGETS FOR THERAPEUTIC INTERVENTION AND PRIMARY PREVENTION. 2004 20 2330 35 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