1 6005 107 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 2 2299 52 EPIGENETIC REGULATION OF AIRWAY EPITHELIUM IMMUNE FUNCTIONS IN ASTHMA. ASTHMA IS A CHRONIC INFLAMMATORY DISEASE OF THE RESPIRATORY TRACT CHARACTERIZED BY RECURRENT BREATHING PROBLEMS RESULTING FROM AIRWAY OBSTRUCTION AND HYPERRESPONSIVENESS. HUMAN AIRWAY EPITHELIUM PLAYS AN IMPORTANT ROLE IN THE INITIATION AND CONTROL OF THE IMMUNE RESPONSES TO DIFFERENT TYPES OF ENVIRONMENTAL FACTORS CONTRIBUTING TO ASTHMA PATHOGENESIS. USING PATTERN RECOGNITION RECEPTORS AIRWAY EPITHELIUM SENSES EXTERNAL STIMULI, SUCH AS ALLERGENS, MICROBES, OR POLLUTANTS, AND SUBSEQUENTLY SECRETES ENDOGENOUS DANGER SIGNALING MOLECULES ALARMING AND ACTIVATING DENDRITIC CELLS. HENCE, AIRWAY EPITHELIAL CELLS NOT ONLY MEDIATE INNATE IMMUNE RESPONSES BUT ALSO BRIDGE THEM WITH ADAPTIVE IMMUNE RESPONSES INVOLVING T AND B CELLS THAT PLAY A CRUCIAL ROLE IN THE PATHOGENESIS OF ASTHMA. THE EFFECTS OF ENVIRONMENTAL FACTORS ON THE DEVELOPMENT OF ASTHMA ARE MEDIATED, AT LEAST IN PART, BY EPIGENETIC MECHANISMS. THOSE COMPRISE CLASSICAL EPIGENETICS INCLUDING DNA METHYLATION AND HISTONE MODIFICATIONS AFFECTING TRANSCRIPTION, AS WELL AS MICRORNAS INFLUENCING TRANSLATION. THE COMMON FEATURE OF SUCH MECHANISMS IS THAT THEY REGULATE GENE EXPRESSION WITHOUT AFFECTING THE NUCLEOTIDE SEQUENCE OF THE GENOMIC DNA. EPIGENETIC MECHANISMS PLAY A PIVOTAL ROLE IN THE REGULATION OF DIFFERENT CELL POPULATIONS INVOLVED IN ASTHMA PATHOGENESIS, WITH THE REMARKABLE EXAMPLE OF T CELLS. RECENTLY, HOWEVER, THERE IS INCREASING EVIDENCE THAT EPIGENETIC MECHANISMS ARE ALSO CRUCIAL FOR THE REGULATION OF AIRWAY EPITHELIAL CELLS, ESPECIALLY IN THE CONTEXT OF EPIGENETIC TRANSFER OF ENVIRONMENTAL EFFECTS CONTRIBUTING TO ASTHMA PATHOGENESIS. IN THIS REVIEW, WE SUMMARIZE THE ACCUMULATING EVIDENCE FOR THIS VERY IMPORTANT ASPECT OF AIRWAY EPITHELIAL CELL PATHOBIOLOGY. 2020 3 5472 33 RESPIRATORY VIRAL INFECTIONS IN EXACERBATION OF CHRONIC AIRWAY INFLAMMATORY DISEASES: NOVEL MECHANISMS AND INSIGHTS FROM THE UPPER AIRWAY EPITHELIUM. RESPIRATORY VIRUS INFECTION IS ONE OF THE MAJOR SOURCES OF EXACERBATION OF CHRONIC AIRWAY INFLAMMATORY DISEASES. THESE EXACERBATIONS ARE ASSOCIATED WITH HIGH MORBIDITY AND EVEN MORTALITY WORLDWIDE. THE CURRENT UNDERSTANDING ON VIRAL-INDUCED EXACERBATIONS IS THAT VIRAL INFECTION INCREASES AIRWAY INFLAMMATION WHICH AGGRAVATES DISEASE SYMPTOMS. RECENT ADVANCES IN IN VITRO AIR-LIQUID INTERFACE 3D CULTURES, ORGANOID CULTURES AND THE USE OF NOVEL HUMAN AND ANIMAL CHALLENGE MODELS HAVE EVOKED NEW UNDERSTANDINGS AS TO THE MECHANISMS OF VIRAL EXACERBATIONS. IN THIS REVIEW, WE WILL FOCUS ON RECENT NOVEL FINDINGS THAT ELUCIDATE HOW RESPIRATORY VIRAL INFECTIONS ALTER THE EPITHELIAL BARRIER IN THE AIRWAYS, THE UPPER AIRWAY MICROBIAL ENVIRONMENT, EPIGENETIC MODIFICATIONS INCLUDING MIRNA MODULATION, AND OTHER CHANGES IN IMMUNE RESPONSES THROUGHOUT THE UPPER AND LOWER AIRWAYS. FIRST, WE REVIEWED THE PREVALENCE OF DIFFERENT RESPIRATORY VIRAL INFECTIONS IN CAUSING EXACERBATIONS IN CHRONIC AIRWAY INFLAMMATORY DISEASES. SUBSEQUENTLY WE ALSO SUMMARIZED HOW RECENT MODELS HAVE EXPANDED OUR APPRECIATION OF THE MECHANISMS OF VIRAL-INDUCED EXACERBATIONS. FURTHER WE HIGHLIGHTED THE IMPORTANCE OF THE VIROME WITHIN THE AIRWAY MICROBIOME ENVIRONMENT AND ITS IMPACT ON SUBSEQUENT BACTERIAL INFECTION. THIS REVIEW CONSOLIDATES THE UNDERSTANDING OF VIRAL INDUCED EXACERBATION IN CHRONIC AIRWAY INFLAMMATORY DISEASES AND INDICATES PATHWAYS THAT MAY BE TARGETED FOR MORE EFFECTIVE MANAGEMENT OF CHRONIC INFLAMMATORY DISEASES. 2020 4 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 5 5552 37 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 6 1606 33 DNA METHYLATION, BACTERIA AND AIRWAY INFLAMMATION: LATEST INSIGHTS. PURPOSE OF REVIEW: DNA METHYLATION IS AN EPIGENETIC MECHANISM THAT HAS BEEN IMPLICATED IN THE PATHOGENESIS OF CHRONIC INFLAMMATORY DISEASES BY REGULATING DIFFERENTIATION, PROLIFERATION, APOPTOSIS, AND ACTIVATION OF IMMUNE CELLS. CHANGES IN THE METHYLATION STATUS OF RELEVANT GENES HAVE BEEN LINKED TO THE ORIGIN, PERPETUATION, AND SEVERITY OF AIRWAY DISEASES. THE DNA METHYLATION PROFILE CAN BE ALSO MODIFIED BY THE ACTION OF VIRAL AND BACTERIAL COLONIZATION. BACTERIA AND SPECIALLY STAPHYLOCOCCUS AUREUS TOXINS ARE RECOGNIZED INFLAMMATORY AMPLIFYING FACTORS IN BOTH LOWER AND UPPER AIRWAY CHRONIC DISEASES. THIS REVIEW SUMMARIZES THE EXISTENT KNOWLEDGE ABOUT THE ROLE OF DNA METHYLATION CHANGES IN CHRONIC AIRWAY DISEASES AND THE CONTRIBUTION OF BACTERIAL INFECTION ON THIS EVENT. RECENT FINDINGS: IT HAS BEEN DEMONSTRATED THAT CHANGES IN DNA METHYLATION, EITHER INTRINSIC OR INDUCED BY ALLERGEN OR INFECTION, MAY BE LINKED TO THE PATHOGENESIS OF ASTHMA AND ALLERGY. THESE CHANGES IN METHYLATION MAY SUPPRESS THE PRODUCTION OF ANTI-INFLAMMATORY MEDIATORS AND INCREASE THE SURVIVAL AND ACTIVATION OF PRO-INFLAMMATORY CELLS, AS WELL AS MODIFY THE IMMUNE RESPONSE IN RESPONSE TO BACTERIAL INFECTION, INCREASING THEIR SURVIVAL AND PATHOGENICITY WITHIN THE INFECTED ORGANISM. SUMMARY: UNDERSTANDING THE INTRINSIC EPIGENETIC MECHANISMS, AS WELL AS THE EFFECT OF ENVIRONMENT -FOR EXAMPLE, BACTERIAL INFECTION IN THE PATHOGENESIS OF AIRWAYS DISEASES - WILL GREATLY IMPROVE THE MANAGEMENT AND THE DIAGNOSIS OF THESE DISEASES. 2015 7 5534 29 ROLE OF AIRWAY EPITHELIAL CELLS IN THE DEVELOPMENT OF DIFFERENT ASTHMA PHENOTYPES. THE TERM (BRONCHIAL) ASTHMA DESCRIBES A DISORDER SYNDROME THAT COMPRISES SEVERAL DISEASE PHENOTYPES, ALL CHARACTERIZED BY CHRONIC INFLAMMATION IN THE BRONCHIAL EPITHELIUM, WITH A VARIETY OF SUBSEQUENT FUNCTIONAL CONSEQUENCES. THUS, THE EPITHELIUM IN THE CONDUCTING AIRWAYS IS THE MAIN LOCALIZATION OF THE COMPLEX PATHOLOGICAL CHANGES IN THE DISEASE. IN THIS REGARD, BRONCHIAL EPITHELIAL CELLS ARE NOT PASSIVELY AFFECTED BY INFLAMMATORY MECHANISMS INDUCED BY IMMUNOLOGICAL PROCESSES BUT RATHER ACTIVELY INVOLVED IN ALL STEPS OF DISEASE DEVELOPMENT FROM INITIATION AND PERPETUATION TO CHRONIFICATION. IN RECENT YEARS IT TURNED OUT THAT BRONCHIAL EPITHELIAL CELLS SHOW A HIGH LEVEL OF STRUCTURAL AND FUNCTIONAL DIVERSITY AND PLASTICITY WITH EPIGENETIC MECHANISMS PLAYING A CRUCIAL ROLE IN THE REGULATION OF THESE PROCESSES. THUS, IT IS QUITE REASONABLE THAT DIFFERENTIAL FUNCTIONAL ACTIVITIES OF THE BRONCHIAL EPITHELIUM ARE INVOLVED IN THE DEVELOPMENT OF DIFFERENT ASTHMA PHENOTYPES AND/OR STAGES OF DISEASE. THE CURRENT KNOWLEDGE ON THIS TOPIC WILL BE DISCUSSED IN THIS REVIEW ARTICLE. 2020 8 3966 44 LONG NONCODING TRANSCRIPTOME IN CHRONIC OBSTRUCTIVE PULMONARY DISEASE. CHRONIC AIRWAY INFLAMMATION FROM RECURRING EXPOSURES TO NOXIOUS ENVIRONMENTAL STIMULI RESULTS IN A PROGRESSIVE AND IRREVERSIBLE AIRFLOW LIMITATION AND THE LUNG PARENCHYMAL DAMAGE THAT CHARACTERIZES CHRONIC OBSTRUCTIVE PULMONARY DISEASE (COPD). THE LARGE VARIABILITY OBSERVED IN THE ONSET AND PROGRESSION OF COPD IS PRIMARILY DRIVEN BY COMPLEX GENE-ENVIRONMENT INTERACTIONS. THE TRANSCRIPTOMIC AND EPIGENETIC MEMORY POTENTIAL OF LUNG EPITHELIAL AND INNATE IMMUNE CELLS DRIVE RESPONSES, SUCH AS MUCUS HYPERREACTIVITY AND AIRWAY REMODELING, THAT ARE TIGHTLY REGULATED BY VARIOUS MOLECULAR MECHANISMS, FOR WHICH SEVERAL CANDIDATE SUSCEPTIBILITY GENES HAVE BEEN DESCRIBED. HOWEVER, THE RECENTLY DESCRIBED NONCODING RNA SPECIES, IN PARTICULAR THE LONG NONCODING RNAS, MAY ALSO HAVE AN IMPORTANT ROLE IN MODULATING PULMONARY RESPONSES TO CHRONIC INHALATION OF TOXIC SUBSTANCES AND THE DEVELOPMENT OF COPD. THIS REVIEW OUTLINES THE FEATURES OF LONG NONCODING RNAS THAT HAVE BEEN IMPLICATED IN REGULATING THE AIRWAY INFLAMMATORY RESPONSES TO CIGARETTE SMOKE EXPOSURE AND THEIR POSSIBLE ASSOCIATION WITH COPD PATHOGENESIS. AS COPD CONTINUES TO DEBILITATE THE INCREASINGLY AGING POPULATION AND CONTRIBUTE TO HIGHER MORBIDITY AND MORTALITY RATES WORLDWIDE, THE SEARCH FOR BETTER BIOMARKERS AND ALTERNATIVE THERAPEUTIC OPTIONS IS PIVOTAL. 2019 9 5325 29 PULMONARY PATHOGEN-INDUCED EPIGENETIC MODIFICATIONS. EPIGENETICS GENERALLY INVOLVES GENETIC CONTROL BY FACTORS OTHER THAN OUR OWN DNA SEQUENCE. RECENT RESEARCH HAS FOCUSED ON DELINEATING THE MECHANISMS OF TWO MAJOR EPIGENETIC PHENOMENA: DNA METHYLATION AND HISTONE MODIFICATION. AS EPIGENETICS INVOLVES MANY CELLULAR PROCESSES, IT IS NO SURPRISE THAT IT CAN ALSO INFLUENCE DISEASE-ASSOCIATED GENE EXPRESSION. A DIRECT LINK BETWEEN RESPIRATORY INFECTIONS, HOST CELL EPIGENETIC REGULATIONS, AND CHRONIC LUNG DISEASES IS STILL UNKNOWN. RECENT STUDIES HAVE REVEALED BACTERIUM- OR VIRUS-INDUCED EPIGENETIC CHANGES IN THE HOST CELLS. IN THIS REVIEW, WE FOCUSED ON RESPIRATORY PATHOGENS (VIRUSES, BACTERIA, AND FUNGI) INDUCED EPIGENETIC MODULATIONS (DNA METHYLATION AND HISTONE MODIFICATION) THAT MAY CONTRIBUTE TO LUNG DISEASE PATHOPHYSIOLOGY BY PROMOTING HOST DEFENSE OR ALLOWING PATHOGEN PERSISTENCE. 2023 10 5406 26 REGULATING THE REGULATORS: MICRORNA AND ASTHMA. ONE OBSTACLE TO DEVELOPING AN EFFECTIVE THERAPEUTIC STRATEGY TO TREAT OR PREVENT ASTHMA IS THAT THE FUNDAMENTAL CAUSES OF ASTHMA ARE NOT TOTALLY UNDERSTOOD. ASTHMA IS THOUGHT TO BE A CHRONIC TH2 IMMUNE-MEDIATED INFLAMMATORY DISEASE. EPIGENETIC CHANGES ARE RECOGNIZED TO PLAY A ROLE IN THE INITIATION AND MAINTENANCE OF A TH2 RESPONSE. MICRORNAS (MIRNAS) ARE KEY EPIGENETIC REGULATORS OF GENE EXPRESSION, AND THEIR EXPRESSION IS HIGHLY REGULATED, THEREFORE, DEREGULATION OF MIRNAS MAY PLAY AN IMPORTANT ROLE IN THE PATHOGENESIS OF ASTHMA. PROFILING CIRCULATING MIRNA MIGHT PROVIDE THE HIGHEST SPECIFICITY AND SENSITIVITY TO DIAGNOSE ASTHMA; SIMILARLY, CORRECTING POTENTIAL DEFECTS IN THE MIRNA REGULATION NETWORK MAY LEAD TO NEW THERAPEUTIC MODALITIES TO TREAT THIS DISEASE. 2011 11 2457 26 EPIGENETIC TARGETS FOR THERAPEUTIC APPROACHES IN COPD AND ASTHMA. NUTRIGENOMICS - POSSIBLE OR ILLUSIVE. OXIDATIVE STRESS GENERATED BY CIGARETTE SMOKING, ENVIRONMENTAL POLLUTION, OR OTHER NOXIOUS PARTICLES LEADS TO EPIGENETIC CHANGES IN THE CELLS OF THE RESPIRATORY TRACT. THEY REFLECT CELL ADAPTATION IN RESPONSE TO CHRONIC EXPOSURE TO EXTERNAL FACTORS. ALTHOUGH THERE IS NO CHANGE IN THE GENETIC CODE, EPIGENETIC CHANGES MAY BE HERITABLE AND TRANSLATED FROM ONE GENERATION TO ANOTHER, ACCUMULATING ABNORMALITIES AND RENDERING CELLS INTO ENTIRELY DIFFERENT PHENOTYPE, CAUSING DISEASE. DNA METHYLATION, POST-TRANSLATION HISTONE MODIFICATION, UBIQUITINATION, SUMOYLATION AND MIRNA TRANSCRIPTIONAL REGULATION ARE THE MAJOR PROCESSES THAT ARE RESPONSIBLE FOR THE EPIGENETIC CONTROL OF GENE EXPRESSION. ALL OF THEM ARE REVERSIBLE. THEY CAN BE REGULATED BY TARGETING SPECIFIC ENZYMES/PROTEINS INVOLVED IN THE PROCESS IN ORDER TO MITIGATE INFLAMMATION. CHRONIC RESPIRATORY DISEASES HAVE EPIGENETIC SIGNATURES THAT AFFECT GENE EXPRESSION IN THE LUNG. TARGETING THEM PROVIDES THE DEVELOPMENT OF NOVEL DIAGNOSTIC AND THERAPEUTIC APPROACHES IN RESPIRATORY MEDICINE. NUTRIGENOMICS REVEALS THE BENEFICIAL EFFECT OF NATURAL PHYTOCHEMICALS, AFFECTING KEY STEPS IN THE SIGNALING PATHWAYS OF CHRONIC RESPIRATORY DISEASES. 2019 12 5573 33 ROLE OF MICRORNA IN SEVERE ASTHMA. THE VARIOUS ROLES OF MICRORNAS (MIRNAS) IN THE EPIGENETIC REGULATION OF HUMAN DISEASE ARE GAINING IMPORTANCE AS AREAS OF RESEARCH, AND A BETTER UNDERSTANDING OF THESE ROLES MAY IDENTIFY TARGETS FOR DEVELOPMENT OF NOVEL THERAPIES FOR SEVERE ASTHMA. MIRNAS, A CLASS OF SMALL NON-CODING RNAS THAT SERVE AS POST-TRANSCRIPTIONAL GENE REPRESSORS, ARE RECOGNIZED AS CRITICAL COMPONENTS IN REGULATING TISSUE HOMEOSTASIS. ALTERATION IN MIRNA EXPRESSION DISRUPTS HOMEOSTASIS AND IS AN UNDERLYING MECHANISM FOR DEVELOPMENT OF CHRONIC RESPIRATORY DISEASES, INCLUDING ASTHMA. DIFFERENTIAL PROFILES OF MIRNA EXPRESSION ARE INVOLVED IN INFLAMMATION AND REMODELING PATHOGENICITY VIA ACTIVATING AIRWAY STRUCTURAL CELLS AND IMMUNE CELLS AND INDUCING CYTOKINE RELEASES. MIRNA ACTION LEADS TO ASTHMA PROGRESSION FROM MILD TO SEVERE STAGES. HERE, CURRENT KNOWLEDGE OF THE HETEROGENEOUS ROLES OF MIRNAS IN SEVERE ASTHMA, INCLUDING BIOLOGICAL MECHANISMS UNDERLYING TH2 AND MACROPHAGE POLARIZATION, TYPE 2 INNATE LYMPHOID CELL (ILC2) BIOLOGY REGULATION, STEROID-RESISTANT ASTHMA PHENOTYPE, AIRWAY SMOOTH MUSCLE (ASM) DYSFUNCTION, AND IMPAIRED ANTI-VIRAL INNATE IMMUNE, ARE REVIEWED. 2019 13 2531 31 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 14 2657 31 EPITHELIAL DYSFUNCTION IN CHRONIC RESPIRATORY DISEASES, A SHARED ENDOTYPE? PURPOSE OF REVIEW: EPITHELIAL BARRIER DEFECTS ARE BEING APPRECIATED IN VARIOUS INFLAMMATORY DISORDERS; HOWEVER, CAUSAL UNDERLYING MECHANISMS ARE LACKING. IN THIS REVIEW, WE DESCRIBE THE DISRUPTION OF THE AIRWAY EPITHELIUM WITH REGARD TO UPPER AND LOWER AIRWAY DISEASES, THE ROLE OF EPIGENETIC ALTERATIONS UNDERLYING THIS PROCESS, AND POTENTIAL NOVEL WAYS OF INTERFERING WITH DYSFUNCTIONAL EPITHELIAL BARRIERS AS A NOVEL THERAPEUTIC APPROACH. RECENT FINDINGS: A DEFECTIVE EPITHELIAL BARRIER, IMPAIRED INNATE DEFENCE MECHANISMS OR HAMPERED EPITHELIAL CELL RENEWAL ARE FOUND IN UPPER AND LOWER AIRWAY DISEASES. BARRIER DYSFUNCTION MIGHT FACILITATE THE ENTRANCE OF FOREIGN SUBSTANCES, INITIATING AND FACILITATING THE ONSET OF DISEASE. LATEST DATA PROVIDED NOVEL INSIGHTS FOR POSSIBLE INVOLVEMENT OF EPIGENETIC ALTERATIONS INDUCED BY INFLAMMATION OR OTHER UNKNOWN MECHANISMS AS A POTENTIAL MECHANISM RESPONSIBLE FOR EPITHELIAL DEFECTS. ADDITIONALLY, THESE MECHANISMS MIGHT PRECEDE DISEASE DEVELOPMENT, AND REPRESENT A NOVEL THERAPEUTIC APPROACH FOR RESTORING EPITHELIAL DEFECTS. SUMMARY: A BETTER UNDERSTANDING OF THE ROLE OF EPIGENETICS IN DRIVING AND MAINTAINING EPITHELIAL DEFECTS IN VARIOUS INFLAMMATORY DISEASES, USING STATE-OF-THE-ART BIOLOGY TOOLS WILL BE CRUCIAL IN DESIGNING NOVEL THERAPIES TO PROTECT OR RECONSTITUTE A DEFECTIVE AIRWAY EPITHELIAL BARRIER. 2020 15 2357 33 EPIGENETIC REGULATION OF PULMONARY INFLAMMATION. PULMONARY DISEASE SUCH AS CHRONIC OBSTRUCTIVE PULMONARY DISEASE (COPD), ASTHMA, PULMONARY FIBROSIS AND PULMONARY HYPERTENSION ARE THE LEADING CAUSE OF DEATHS. MORE IMPORTANTLY, LUNG DISEASES ARE ON THE RISE AND ENVIRONMENTAL FACTORS INDUCED EPIGENETIC MODIFICATIONS ARE MAJOR PLAYERS ON THIS INCREASED PREVALENCE. IT HAS BEEN REPORTED THAT DYSREGULATION OF GENES INVOLVED IN EPIGENETIC REGULATION SUCH AS THE HISTONE DEACETYLASE (HDACS) AND HISTONE ACETYLTRANSFERASE (HATS) PLAY IMPORTANT ROLE IN LUNG HEALTH AND PULMONARY DISEASE PATHOGENESIS. INFLAMMATION IS AN ESSENTIAL COMPONENT OF RESPIRATORY DISEASES. INJURY AND INFLAMMATION TRIGGER RELEASE OF EXTRACELLULAR VESICLES THAT CAN ACT AS EPIGENETIC MODIFIERS THROUGH TRANSFER OF EPIGENETIC REGULATORS SUCH AS MICRORNAS (MIRNAS), LONG NON-CODING RNAS (LNCRNAS), PROTEINS AND LIPIDS, FROM ONE CELL TO ANOTHER. THE IMMUNE DYSREGULATIONS CAUSED BY THE CARGO CONTENTS ARE IMPORTANT CONTRIBUTORS OF RESPIRATORY DISEASE PATHOGENESIS. N6 METHYLATION OF RNA IS ALSO EMERGING TO BE A CRITICAL MECHANISM OF EPIGENETIC ALTERATION AND UPREGULATION OF IMMUNE RESPONSES TO ENVIRONMENTAL STRESSORS. EPIGENETIC CHANGES SUCH AS DNA METHYLATION ARE STABLE AND OFTEN LONG TERM AND CAUSE ONSET OF CHRONIC LUNG CONDITIONS. THESE EPIGENETIC PATHWAYS ARE ALSO BEING UTILIZED FOR THERAPEUTIC INTERVENTION IN SEVERAL LUNG CONDITIONS. 2023 16 3028 27 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 17 6533 37 TRANSCRIPTIONAL REGULATION OF INFLAMMATORY GENES ASSOCIATED WITH SEVERE ASTHMA. THE 10% OF PATIENTS WITH THE MOST SEVERE ASTHMA ARE RESPONSIBLE FOR A LARGE PART OF HEALTHCARE EXPENDITURE AND MORBIDITY. UNDERSTANDING THE PROCESSES INVOLVED IS KEY IF NEW THERAPEUTIC APPROACHES ARE TO BE DEVELOPED. EVIDENCE IS ACCUMULATING THAT CHRONIC DISEASES SUCH AS ASTHMA ARE ASSOCIATED WITH TEMPORAL AND SPATIAL ALTERATIONS IN THE PATTERN OF INFLAMMATORY GENE EXPRESSION WITHIN THE AIRWAYS. EXPRESSION OF THESE GENES CAN BE REGULATED BY TRANSCRIPTIONAL, POSTTRANSCRIPTIONAL, TRANSLATIONAL AND EPIGENETIC MECHANISMS. IT IS WELL ESTABLISHED THAT BINDING OF ACTIVATED TRANSCRIPTION FACTORS TO SPECIFIC INDUCIBLE GENE PROMOTER SITES IS TIGHTLY CONTROLLED BY CHROMATIN STATE AS A RESULT OF HISTONE MODIFICATIONS, PARTICULARLY THE BALANCE BETWEEN HISTONE ACETYLATION AND DEACETYLATION [1]. THE INTERACTION BETWEEN TRANSCRIPTION FACTORS AND THE PROMOTER IS KEY TO THE DIVERSIFICATION OF GENE EXPRESSION IN A TIME DEPENDENT MANNER LEADING TO ALTERED GENE EXPRESSION PROFILES. ALTERATIONS OF THE ACCESSIBILITY OF TRANSCRIPTION FACTORS TO THE DNA CAN HAVE RESIDING EFFECTS UPON GENE TRANSCRIPTION. THIS REVIEW WILL FOCUS ON THE REGULATION OF SEVERAL GROUPS OF KEY GENES WHICH ARE INVOLVED IN CHRONIC AIRWAY INFLAMMATION AND REMODELLING IN ASTHMA DRAWING MAINLY FROM OUR EXPERIENCE OF STUDYING THESE PROCESSES IN AIRWAY SMOOTH MUSCLE CELLS. AN OVERVIEW IS SHOWN IN FIGURE 1. 2011 18 4445 27 MOLECULAR LINKS BETWEEN COPD AND LUNG CANCER: NEW TARGETS FOR DRUG DISCOVERY? COPD AND LUNG CANCER ARE LEADING CAUSES OF MORBIDITY AND MORTALITY WORLDWIDE, AND THEY SHARE A COMMON ENVIRONMENTAL RISK FACTOR IN CIGARETTE SMOKE EXPOSURE AND A GENETIC PREDISPOSITION REPRESENTED BY THEIR INCIDENCE IN ONLY A FRACTION OF SMOKERS. THIS REFLECTS THE ABILITY OF CIGARETTE SMOKE TO INDUCE AN INFLAMMATORY RESPONSE IN THE AIRWAYS OF SUSCEPTIBLE SMOKERS. MOREOVER, COPD COULD BE A DRIVING FACTOR IN LUNG CANCER, BY INCREASING OXIDATIVE STRESS AND THE RESULTING DNA DAMAGE AND REPRESSION OF THE DNA REPAIR MECHANISMS, CHRONIC EXPOSURE TO PRO-INFLAMMATORY CYTOKINES, REPRESSION OF INNATE IMMUNITY AND INCREASED CELLULAR PROLIFERATION. AREAS COVERED: WE HAVE FOCUSED OUR REVIEW ON THE POTENTIAL PATHOGENIC MOLECULAR LINKS BETWEEN TOBACCO SMOKING-RELATED COPD AND LUNG CANCER AND THE POTENTIAL MOLECULAR TARGETS FOR NEW DRUG DEVELOPMENT BY UNDERSTANDING THE COMMON SIGNALING PATHWAYS INVOLVED IN COPD AND LUNG CANCER. EXPERT COMMENTARY: RESEARCH IN THIS FIELD IS MOSTLY LIMITED TO ANIMAL MODELS OR SMALL CLINICAL TRIALS. LARGE CLINICAL TRIALS ARE NEEDED BUT MOSTLY COMBINED MODELS OF COPD AND LUNG CANCER ARE NECESSARY TO INVESTIGATE THE PROCESSES CAUSED BY CHRONIC INFLAMMATION, INCLUDING GENETIC AND EPIGENETIC ALTERATION, AND THE EXPRESSION OF INFLAMMATORY MEDIATORS THAT LINK COPD AND LUNG CANCER, TO IDENTIFY NEW MOLECULAR THERAPEUTIC TARGETS. 2019 19 2333 34 EPIGENETIC REGULATION OF INFLAMMATION: THE METABOLOMICS CONNECTION. EPIGENETIC FACTORS ARE CONSIDERED THE REGULATOR OF COMPLEX MACHINERY BEHIND INFLAMMATORY DISORDERS AND SIGNIFICANTLY CONTRIBUTED TO THE EXPRESSION OF INFLAMMATION-ASSOCIATED GENES. EPIGENETIC MODIFICATIONS MODULATE VARIATION IN THE EXPRESSION PATTERN OF TARGET GENES WITHOUT AFFECTING THE DNA SEQUENCE. THE CURRENT KNOWLEDGE OF EPIGENETIC RESEARCH FOCUSED ON THEIR ROLE IN THE PATHOGENESIS OF VARIOUS INFLAMMATORY DISEASES THAT CAUSES MORBIDITY AND MORTALITY WORLDWIDE. INFLAMMATORY DISEASES ARE CATEGORIZED AS ACUTE AND CHRONIC BASED ON THE DISEASE SEVERITY AND ARE REGULATED BY THE EXPRESSION PATTERN OF VARIOUS GENES. HENCE, UNDERSTANDING THE ROLE OF EPIGENETIC MODIFICATIONS DURING INFLAMMATION PROGRESSION WILL CONTRIBUTE TO THE DISEASE OUTCOMES AND THERAPEUTIC APPROACHES. THIS REVIEW ALSO FOCUSES ON THE METABOLOMICS APPROACH ASSOCIATED WITH THE STUDY OF INFLAMMATORY DISORDERS. INFLAMMATORY RESPONSES AND METABOLIC REGULATION ARE HIGHLY INTEGRATED AND VARIOUS ADVANCED TECHNIQUES ARE ADOPTED TO STUDY THE METABOLIC SIGNATURE MOLECULES. HERE WE DISCUSS SEVERAL METABOLOMICS APPROACHES USED TO LINK INFLAMMATORY DISORDERS AND EPIGENETIC CHANGES. WE PROPOSED THAT DECIPHERING THE MECHANISM BEHIND THE INFLAMMATION-METABOLISM LOOP MAY HAVE IMMENSE IMPORTANCE IN BIOMARKERS RESEARCH AND MAY ACT AS A PRINCIPAL COMPONENT IN DRUG DISCOVERY AS WELL AS THERAPEUTIC APPLICATIONS. 2022 20 6735 35 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