1 6808 55 [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 2 1760 24 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 3 3698 21 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 4 6303 24 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 5 530 22 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 6 2861 20 FROM TRAINED IMMUNITY IN ALLERGY TO TRAINED IMMUNITY-BASED ALLERGEN VACCINES. INNATE IMMUNE CELLS EXPERIENCE LONG LASTING METABOLIC AND EPIGENETIC CHANGES AFTER AN ENCOUNTER WITH SPECIFIC STIMULI. THIS FACILITATES ENHANCED IMMUNE RESPONSES UPON SECONDARY EXPOSITION TO BOTH THE SAME AND UNRELATED PATHOGENS, A PROCESS TERMED TRAINED IMMUNITY. TRAINED IMMUNITY-BASED VACCINES (TIBV) ARE VACCINES ABLE TO INDUCE INNATE IMMUNE MEMORY, THUS CONFERRING HETEROLOGOUS PROTECTION AGAINST A BROAD RANGE OF PATHOGENS. WHILE TRAINED IMMUNITY HAS BEEN WELL DOCUMENTED IN THE CONTEXT OF INFECTIONS AND MULTIPLE IMMUNE-MEDIATED DISEASES, THE ROLE OF INNATE IMMUNE MEMORY AND ITS CONTRIBUTION TO THE INITIATION AND MAINTENANCE OF CHRONIC ALLERGIC DISEASES REMAINS POORLY UNDERSTOOD. OVER THE LAST YEARS, DIFFERENT STUDIES ATTEMPTING TO UNCOVER THE ROLE OF TRAINED IMMUNITY IN ALLERGY HAVE EMERGED. EXPOSITION TO ENVIRONMENTAL FACTORS IMPACTING ALLERGY DEVELOPMENT SUCH AS ALLERGENS OR VIRUSES INDUCES THE REPROGRAMMING OF INNATE IMMUNE CELLS TO ACQUIRE A MORE PRO-INFLAMMATORY PHENOTYPE IN THE CONTEXT OF ASTHMA OR FOOD ALLERGY. SEVERAL STUDIES HAVE CONVINCINGLY DEMONSTRATED THAT PREVENTION OF VIRAL INFECTIONS USING TIBV CONTRIBUTES TO REDUCE WHEEZING ATTACKS IN CHILDREN, WHICH REPRESENT A HIGH-RISK FACTOR FOR ASTHMA DEVELOPMENT LATER IN LIFE. INNATE IMMUNE CELLS TRAINED WITH SPECIFIC STIMULI MIGHT ALSO ACQUIRE ANTI-INFLAMMATORY FEATURES AND PROMOTE TOLERANCE, WHICH MAY HAVE IMPORTANT IMPLICATIONS FOR CHRONIC INFLAMMATORY DISEASES SUCH AS ALLERGIES. RECENT FINDINGS SHOWED THAT ALLERGOID-MANNAN CONJUGATES, WHICH ARE NEXT GENERATION VACCINES FOR ALLERGEN-SPECIFIC IMMUNOTHERAPY (AIT), ARE ABLE TO REPROGRAM MONOCYTES INTO TOLEROGENIC DENDRITIC CELLS BY MECHANISMS DEPENDING ON METABOLIC AND EPIGENETIC REWIRING. A BETTER UNDERSTANDING OF THE UNDERLYING MECHANISMS OF TRAINED IMMUNITY IN ALLERGY WILL PAVE THE WAY FOR THE DESIGN OF NOVEL TRAINED IMMUNITY-BASED ALLERGEN VACCINES AS POTENTIAL ALTERNATIVE STRATEGIES FOR THE PREVENTION AND TREATMENT OF ALLERGIC DISEASES. 2023 7 6877 25 [REASONS FOR THE DEVELOPMENT OF ALLERGIES IN CHILDREN]. ALLERGIES ARE ONE OF THE MOST COMMON CHRONIC DISEASES IN CHILDHOOD, CONTRIBUTING TO A TREMENDOUS MEDICAL AND ECONOMICAL BURDEN IN HEALTH CARE SYSTEMS OF MOST INDUSTRIALIZED COUNTRIES. THE DEVELOPMENT OF ALLERGIES IS DEPENDENT ON A COMPLEX INTERACTION OF-AMONG OTHERS-ENVIRONMENTAL FACTORS, NUTRITION, GENETIC AND EPIGENETIC MECHANISMS AS WELL AS THE MICROBIOME. THESE DIVERSE FACTORS CAN INFLUENCE EARLY LIFE IMMUNE REGULATION INCLUDING INNATE AND ADAPTIVE IMMUNE MECHANISMS IN A COMPLEX FASHION. IN CASE OF ANY CHILDHOOD ALLERGIES HAVE INCREASED SIGNIFICANTLY IN PAST DECADES. IN ADDITION TO ENVIRONMENTAL FACTORS AND NUTRITION, GENETIC AND EPIGENETIC MECHANISMS AS WELL AS THE MICROBIOME OF CHILDREN PLAY AN IMPORTANT ROLE. OF RELEVANCE IS THE WAY IN WHICH THESE DIVERSE FACTORS INFLUENCE EARLY IMMUNE DEVELOPMENT OF THE INNATE AND ADAPTIVE IMMUNE SYSTEMS OF CHILDREN. THEIR COMPLEX REGULATION IS DECISIVE FOR WHETHER OR NOT A CHILD DEVELOPS AN ALLERGY THAT MANIFESTS IN MOST CASES AS ATOPIC DERMATITIS, BRONCHIAL ASTHMA, OR ALLERGIC RHINO CONJUNCTIVITIS, OR WHETHER A CHILD DEVELOPS AN IMMUNE TOLERANCE. THESE INFLUENCES CAN BEGIN PRENATALLY, ALREADY SETTING THE COURSE FOR LATER IMMUNE SYSTEM DEVELOPMENT AND OCCURRENCE OF DISEASE. 2019 8 2519 23 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 9 4872 24 OUTSIDE-IN HYPOTHESIS REVISITED: THE ROLE OF MICROBIAL, EPITHELIAL, AND IMMUNE INTERACTIONS. OBJECTIVE: OUR UNDERSTANDING OF THE ORIGIN OF ALLERGIC DISEASES HAS INCREASED IN RECENT YEARS, HIGHLIGHTING THE IMPORTANCE OF MICROBIAL DYSBIOSIS AND EPITHELIAL BARRIER DYSFUNCTION IN AFFECTED TISSUES. EXPLORING THE MICROBIAL-EPITHELIAL-IMMUNE CROSSTALK UNDERLYING THE MECHANISMS OF ALLERGIC DISEASES WILL ALLOW THE DEVELOPMENT OF NOVEL PREVENTION AND TREATMENT STRATEGIES FOR ALLERGIC DISEASES. DATA SOURCES: THIS REVIEW SUMMARIZES THE RECENT ADVANCES IN MICROBIAL, EPITHELIAL, AND IMMUNE INTERACTIONS IN ATOPIC DERMATITIS, ALLERGIC RHINITIS, CHRONIC RHINOSINUSITIS, AND ASTHMA. STUDY SELECTIONS: WE PERFORMED A LITERATURE SEARCH, IDENTIFYING RELEVANT RECENT PRIMARY ARTICLES AND REVIEW ARTICLES. RESULTS: DYNAMIC CROSSTALK BETWEEN THE ENVIRONMENTAL FACTORS AND MICROBIAL, EPITHELIAL, AND IMMUNE CELLS IN THE DEVELOPMENT OF ATOPIC DERMATITIS, ALLERGIC RHINITIS, CHRONIC RHINOSINUSITIS, AND ASTHMA UNDERLIES THE PATHOGENESIS OF THESE DISEASES. THERE IS SUBSTANTIAL EVIDENCE IN THE LITERATURE SUGGESTING THAT ENVIRONMENTAL FACTORS DIRECTLY AFFECT BARRIER FUNCTION OF THE EPITHELIUM. IN ADDITION, T-HELPER 2 (T(H)2) CELLS, TYPE 2 INNATE LYMPHOID CELLS, AND THEIR CYTOKINE INTERLEUKIN 13 (IL-13) DAMAGE SKIN AND LUNG BARRIERS. THE EFFECTS OF ENVIRONMENTAL FACTORS MAY AT LEAST IN PART BE MEDIATED BY EPIGENETIC MECHANISMS. HISTONE DEACETYLASE ACTIVATION BY TYPE 2 IMMUNE RESPONSE HAS A MAJOR EFFECT ON LEAKY BARRIERS AND BLOCKING OF HISTONE DEACETYLASE ACTIVITY CORRECTS THE DEFECTIVE BARRIER IN HUMAN AIR-LIQUID INTERFACE CULTURES AND MOUSE MODELS OF ALLERGIC ASTHMA WITH RHINITIS. WE ALSO PRESENT AND DISCUSS A NOVEL DEVICE TO DETECT AND MONITOR SKIN BARRIER DYSFUNCTION, WHICH PROVIDES AN OPPORTUNITY TO RAPIDLY AND ROBUSTLY ASSESS DISEASE SEVERITY. CONCLUSION: A COMPLEX INTERPLAY BETWEEN ENVIRONMENTAL FACTORS, EPITHELIUM, AND THE IMMUNE SYSTEM IS INVOLVED IN THE DEVELOPMENT OF SYSTEMIC ALLERGIC DISEASES. 2020 10 6048 20 THE CONCEPTS OF ASTHMA ENDOTYPES AND PHENOTYPES TO GUIDE CURRENT AND NOVEL TREATMENT STRATEGIES. ASTHMA, A COMMON, NON-COMMUNICABLE CHRONIC DISEASE AFFECTS OVER 300 MILLION INDIVIDUALS WORLDWIDE. THE WESTERN WORLD LIFESTYLE IS CLAIMED TO BE RESPONSIBLE FOR THIS HIGH AND INCREASING PREVALENCE. ASTHMA HAS BEEN DEFINED AS A SYNDROME WITH VARIOUS PHENOTYPES AND ENDOTYPES, ALLERGIC ASTHMA AND TYPE 2 ASTHMA BEING THE MOST FREQUENT. A GREAT INCREASE IN PREVALENCE OF ALLERGIC DISEASES HAS NECESSITATED INTENSIVE INVESTIGATIONS BOTH FOR UNDERSTANDING THE UNDERLYING MECHANISMS AND FOR THE DEVELOPMENT OF NOVEL THERAPY OPTIONS WITH LONG-TERM EFFICACY AND LIMITED SIDE-EFFECTS. ALLERGIC PATIENTS DEMONSTRATE UNIQUE PRESENTATIONS WITH VARIABLE VISIBLE CHARACTERISTICS AND DISEASE OUTCOMES DEPENDING ON DIFFERENT MOLECULAR MECHANISMS, RELATED TO INFLUENCE OF GENES AND EPIGENETIC CONTROL BY MICRO- AND MACRO-ENVIRONMENT. AREAS COVERED: THIS ARTICLE REVIEWS THE DEFINITION OF ASTHMA PHENOTYPES AND POSSIBLE ENDOTYPES, ADVANCES IN ALLERGY-IMMUNOLOGY FIELD AND CONTEMPORARY PERSONALIZED THERAPY OPTIONS FOR ASTHMA. EXPERT COMMENTARY: BETTER UNDERSTANDING OF THE COMPLEX IMMUNE NETWORK OF ALLERGIC INFLAMMATION AND KEY PLAYERS OF IMMUNITY IS CONTINUOUSLY BEING PROVIDED FOR CLARIFICATION OF ASTHMA SUB-TYPES. SUCCESSFUL THERAPY OF ASTHMA REQUIRES BETTER DEFINITION OF UNDERLYING PATHOGENESIS, WHICH SEQUENTIALLY COULD END UP WITH 'CUSTOM-TAILORED' INDIVIDUALIZED, EVIDENCE-BASED AND MORE PRECISE THERAPY OPTIONS; A NEW ERA TERMED AS 'PRECISION MEDICINE'. ENDOTYPE, PHENOTYPE, THERATYPE AND BIOMARKER TERMS ARISE AS MAJOR KEYWORDS IN PRECISION/PERSONALIZED MEDICINE. 2018 11 2531 18 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 12 3580 24 IMPACT OF PERINATAL ENVIRONMENTAL TOBACCO SMOKE ON THE DEVELOPMENT OF CHILDHOOD ALLERGIC DISEASES. ALLERGIC DISEASES SUCH AS ASTHMA, ALLERGIC RHINITIS, ATOPIC DERMATITIS, AND FOOD ALLERGY, ARE MOST COMMON CHRONIC, NONCOMMUNICABLE DISEASES IN CHILDHOOD. IN THE PAST FEW DECADES, THE PREVALENCE HAS INCREASED ABRUPTLY WORLDWIDE. THERE ARE 2 POSSIBLE EXPLANATIONS FOR THE RISING PREVALENCE OF ALLERGIC DISEASES WORLDWIDE, THAT AN INCREASED DISEASE-AWARENESS OF PHYSICIAN, PATIENT, OR CAREGIVERS, AND AN ABRUPT EXPOSURE TO UNKNOWN HAZARDS. UNFORTUNATELY, THE UNDERLYING MECHANISMS REMAIN LARGELY UNKNOWN. DESPITE THE CONTINUING EFFORTS WORLDWIDE, THE ETIOLOGIES AND RISING PREVALENCE REMAIN UNCLEAR. THUS, IT IS IMPORTANT TO IDENTIFY AND CONTROL RISK FACTORS IN THE SUSCEPTIBLE INDIVIDUAL FOR THE BEST PREVENTION AND MANAGEMENT. GENETIC SUSCEPTIBILITY OR ENVIRONMENTS MAY BE A POTENTIAL BACKGROUND FOR THE DEVELOPMENT OF ALLERGIC DISEASE, HOWEVER THEY ALONE CANNOT EXPLAIN THE RISING PREVALENCE WORLDWIDE. THERE IS GROWING EVIDENCE THAT EPIGENETIC CHANGE DEPENDS ON THE GENE, ENVIRONMENT, AND THEIR INTERACTIONS, MAY INDUCE A LONG-LASTING ALTERED GENE EXPRESSION AND THE CONSEQUENT DEVELOPMENT OF ALLERGIC DISEASES. IN EPIGENETIC MECHANISMS, ENVIRONMENTAL TOBACCO SMOKE (ETS) EXPOSURE DURING CRITICAL PERIOD (I.E., DURING PREGNANCY AND EARLY LIFE) ARE CONSIDERED AS A POTENTIAL CAUSE OF THE DEVELOPMENT OF CHILDHOOD ALLERGIC DISEASES. HOWEVER, THE CAUSAL RELATIONSHIP IS STILL UNCLEAR. THIS REVIEW AIMED TO HIGHLIGHT THE IMPACT OF ETS EXPOSURE DURING THE PERINATAL PERIOD ON THE DEVELOPMENT OF CHILDHOOD ALLERGIC DISEASES AND TO PROPOSE A FUTURE RESEARCH DIRECTION. 2016 13 5552 23 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 14 2369 17 EPIGENETIC REGULATION OF T-HELPER CELL DIFFERENTIATION, MEMORY, AND PLASTICITY IN ALLERGIC ASTHMA. AN ESTIMATED 300 MILLION PEOPLE CURRENTLY SUFFER FROM ASTHMA, WHICH CAUSES APPROXIMATELY 250 000 DEATHS A YEAR. ALLERGEN-SPECIFIC T-HELPER (TH) CELLS PRODUCE CYTOKINES THAT INDUCE MANY OF THE HALLMARK FEATURES OF ASTHMA INCLUDING AIRWAYS HYPERREACTIVITY, EOSINOPHILIC AND NEUTROPHILIC INFLAMMATION, MUCUS HYPERSECRETION, AND AIRWAY REMODELING. CYTOKINE-PRODUCING TH SUBSETS INCLUDING TH1 (IFN-GAMMA), TH2 (IL-4, IL-5, IL-13), TH9 (IL-9), TH17 (IL-17), TH22 (IL-22), AND T REGULATORY (IL-10) CELLS HAVE ALL BEEN SUGGESTED TO PLAY A ROLE IN THE DEVELOPMENT OF ASTHMA. TH DIFFERENTIATION INVOLVES GENETIC REGULATION OF GENE EXPRESSION THROUGH THE CONCERTED ACTION OF CYTOKINES, TRANSCRIPTION FACTORS, AND EPIGENETIC REGULATORS. WE DESCRIBE HOW TH DIFFERENTIATION AND PLASTICITY IS REGULATED BY EPIGENETIC HISTONE AND DNA MODIFICATIONS, WITH A FOCUS ON THE REGULATION OF HISTONE METHYLATION BY MEMBERS OF THE POLYCOMB AND TRITHORAX COMPLEXES. IN ADDITION, WE OUTLINE ENVIRONMENTAL INFLUENCES THAT COULD INFLUENCE EPIGENETIC REGULATION OF TH CELLS AND DISCUSS THE POTENTIAL TO REGULATE TH PLASTICITY AND FUNCTION THROUGH DRUGS TARGETING THE EPIGENETIC MACHINERY. IT IS ALSO BECOMING APPARENT THAT EPIGENETIC REGULATION OF ALLERGEN-SPECIFIC MEMORY TH CELLS MAY BE IMPORTANT IN THE DEVELOPMENT AND PERSISTENCE OF CHRONIC ALLERGIES. FINALLY, WE DESCRIBE HOW EPIGENETIC MODIFIERS REGULATE CYTOKINE MEMORY IN TH CELLS AND DESCRIBE RECENTLY IDENTIFIED HYBRID, PLASTIC, AND PATHOGENIC MEMORY TH SUBSETS THE CONTEXT OF ALLERGIC ASTHMA. 2017 15 2160 20 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 16 529 19 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 17 3711 16 INHALED DRUG DELIVERY FOR THE TARGETED TREATMENT OF ASTHMA. ASTHMA IS A CHRONIC LUNG DISEASE AFFECTING MILLIONS WORLDWIDE. WHILE CLASSICALLY ACKNOWLEDGED TO RESULT FROM ALLERGEN-DRIVEN TYPE 2 INFLAMMATORY RESPONSES LEADING TO IGE AND CYTOKINE PRODUCTION AND THE INFLUX OF IMMUNE CELLS SUCH AS MAST CELLS AND EOSINOPHILS, THE WIDE RANGE IN ASTHMATIC PATHOBIOLOGICAL SUBTYPES LEAD TO HIGHLY VARIABLE RESPONSES TO ANTI-INFLAMMATORY THERAPIES. THUS, THERE IS A NEED TO DEVELOP PATIENT-SPECIFIC THERAPIES CAPABLE OF ADDRESSING THE FULL SPECTRUM OF ASTHMATIC LUNG DISEASE. MOREOVER, DELIVERY OF TARGETED TREATMENTS FOR ASTHMA DIRECTLY TO THE LUNG MAY HELP TO MAXIMIZE THERAPEUTIC BENEFIT, BUT CHALLENGES REMAIN IN DESIGN OF EFFECTIVE FORMULATIONS FOR THE INHALED ROUTE. IN THIS REVIEW, WE DISCUSS THE CURRENT UNDERSTANDING OF ASTHMATIC DISEASE PROGRESSION AS WELL AS GENETIC AND EPIGENETIC DISEASE MODIFIERS ASSOCIATED WITH ASTHMA SEVERITY AND EXACERBATION OF DISEASE. WE ALSO OVERVIEW THE LIMITATIONS OF CLINICALLY AVAILABLE TREATMENTS FOR ASTHMA AND DISCUSS PRE-CLINICAL MODELS OF ASTHMA USED TO EVALUATE NEW THERAPIES. BASED ON THE SHORTCOMINGS OF EXISTING TREATMENTS, WE HIGHLIGHT RECENT ADVANCES AND NEW APPROACHES TO TREAT ASTHMA VIA INHALATION FOR MONOCLONAL ANTIBODY DELIVERY, MUCOLYTIC THERAPY TO TARGET AIRWAY MUCUS HYPERSECRETION AND GENE THERAPIES TO ADDRESS UNDERLYING DRIVERS OF DISEASE. FINALLY, WE CONCLUDE WITH DISCUSSION ON THE PROSPECTS FOR AN INHALED VACCINE TO PREVENT ASTHMA. 2023 18 2138 19 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 19 1926 25 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 20 1640 18 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