1 2192 119 EPIGENETIC METHODS AND TWIN STUDIES. GENOMIC PREDISPOSITION FAILS TO FULLY EXPLAIN THE ONSET OF COMPLEX DISEASES, WHICH IS WELL ILLUSTRATED BY THE LARGELY INCOMPLETE CONCORDANCE AMONG MONOZYGOTIC TWINS. EPIGENETIC MECHANISMS, INCLUDING DNA METHYLATION, CHROMATIN REMODELING, AND NON-CODING RNA, ARE THE LINK BETWEEN ENVIRONMENTAL STIMULI AND DISEASE ONSET ON A PERMISSIVE GENETIC BACKGROUND IN AUTOIMMUNE AND CHRONIC INFLAMMATORY DISEASES. AUTOIMMUNE DISEASES NOW INCLUDE ALMOST 100 CONDITIONS AND ARE ESTIMATED TO CUMULATIVELY AFFECT UP TO 5% OF THE WORLD POPULATION WITH A HEALTHCARE EXPENDITURE SUPERIOR TO CANCER WORLDWIDE. MANY ADVANCES IN MEDICINE HAVE BEEN MADE TO TREAT THESE CONDITIONS BUT THERE ARE STILL GAPS, AND AN INNOVATIVE AND EFFICIENT THERAPY IS NEEDED. SYSTEMIC AUTOIMMUNE DISEASES INCLUDE RHEUMATOID ARTHRITIS, SYSTEMIC LUPUS ERYTHEMATOSUS, SYSTEMIC SCLEROSIS, SJOGREN SYNDROME, POLYMYOSITIS, AND DERMATOMYOSITIS. MONOZYGOTIC TWINS DISCORDANT FOR ANY DISEASE OFFER AN IDEAL STUDY DESIGN AS THEY ARE MATCHED FOR MANY FACTORS, INCLUDING GENETIC VARIATION AND THIS IS A REAL ADVANTAGE FOR EPIGENETICS STUDY. WE WILL HEREIN DISCUSS THE AVAILABLE DATA IN THE EPIGENETIC DIFFERENCES LEADING TO DISEASE DISCORDANCE IN MZ TWINS FOR SYSTEMIC LUPUS ERYTHEMATOSUS, RHEUMATOID ARTHRITIS, AND SYSTEMIC SCLEROSIS. 2020 2 6262 62 THE MULTIFACETED FUNCTIONAL ROLE OF DNA METHYLATION IN IMMUNE-MEDIATED RHEUMATIC DISEASES. GENOMIC PREDISPOSITION CANNOT EXPLAIN THE ONSET OF COMPLEX DISEASES, AS WELL ILLUSTRATED BY THE LARGELY INCOMPLETE CONCORDANCE AMONG MONOZYGOTIC TWINS. EPIGENETIC MECHANISMS, INCLUDING DNA METHYLATION, CHROMATIN REMODELLING AND NON-CODING RNA, ARE CONSIDERED TO BE THE LINK BETWEEN ENVIRONMENTAL STIMULI AND DISEASE ONSET ON A PERMISSIVE GENETIC BACKGROUND IN AUTOIMMUNE AND CHRONIC INFLAMMATORY DISEASES. THE PARADIGMATIC CASES OF RHEUMATOID ARTHRITIS (RA), SYSTEMIC LUPUS ERYTHEMATOSUS (SLE), SYSTEMIC SCLEROSIS (SSC), SJOGREN'S SYNDROME (SJS) AND TYPE-1 DIABETES (T1D) SHARE THE LOSS OF IMMUNOLOGICAL TOLERANCE TO SELF-ANTIGEN INFLUENCED BY SEVERAL FACTORS, WITH A LARGELY INCOMPLETE ROLE OF INDIVIDUAL GENOMIC SUSCEPTIBILITY. THE MOST WIDELY INVESTIGATED EPIGENETIC MECHANISM IS DNA METHYLATION WHICH IS ASSOCIATED WITH GENE SILENCING AND IS DUE TO THE BINDING OF METHYL-CPG BINDING DOMAIN (MBD)-CONTAINING PROTEINS, SUCH AS MECP2, TO 5-METHYLCYTOSINE (5MC). INDEED, A CAUSAL RELATIONSHIP OCCURS BETWEEN DNA METHYLATION AND TRANSCRIPTION FACTORS OCCUPANCY AND RECRUITMENT AT SPECIFIC GENOMIC LOCUS. IN MOST CASES, THE RESULTS OBTAINED IN DIFFERENT STUDIES ARE CONTROVERSIAL IN TERMS OF DNA METHYLATION COMPARISON WHILE FASCINATING EVIDENCE COMES FROM THE COMPARISON OF THE EPIGENOME IN CLINICALLY DISCORDANT MONOZYGOTIC TWINS. IN THIS MANUSCRIPT, WE WILL REVIEW THE MECHANISMS OF EPIGENETICS AND DNA METHYLATION CHANGES IN SPECIFIC IMMUNE-MEDIATED RHEUMATIC DISEASES TO HIGHLIGHT REMAINING UNMET NEEDS AND TO IDENTIFY POSSIBLE SHARED MECHANISMS BEYOND DIFFERENT TISSUE INVOLVEMENTS WITH COMMON THERAPEUTIC OPPORTUNITIES. KEY POINTS * DNA METHYLATION HAS A CRUCIAL ROLE IN REGULATING AND TUNING THE IMMUNE SYSTEM. * EVIDENCES SUGGEST THAT DYSREGULATION OF DNA METHYLATION IS PIVOTAL IN THE CONTEXT OF IMMUNE-MEDIATED RHEUMATIC DISEASES. * DNA METHYLATION DYSREGULATION IN FOXP3 AND INTERFERONS-RELATED GENES IS SHARED WITHIN SEVERAL AUTOIMMUNE DISEASES. * DNA METHYLATION IS AN ATTRACTIVE MARKER FOR DIAGNOSIS AND THERAPY. 2021 3 2516 38 EPIGENETICS AND SYSTEMIC LUPUS ERYTHEMATOSUS: UNMET NEEDS. SYSTEMIC LUPUS ERYTHEMATOSUS (SLE) IS A CHRONIC RELAPSING-REMITTING AUTOIMMUNE DISEASE AFFECTING SEVERAL ORGANS. ALTHOUGH THE MANAGEMENT OF LUPUS PATIENTS HAS IMPROVED IN THE LAST YEARS, SEVERAL ASPECTS STILL REMAIN CHALLENGING. MORE SENSITIVE AND SPECIFIC BIOMARKERS FOR AN EARLY DIAGNOSIS AS WELL AS FOR MONITORING DISEASE ACTIVITY AND TISSUE DAMAGE ARE NEEDED. GENOME-WIDE ASSOCIATION AND GENE MAPPING STUDIES HAVE SUPPORTED THE GENETIC BACKGROUND FOR SLE SUSCEPTIBILITY. HOWEVER, THE RELATIVELY MODEST RISK ASSOCIATION AND THE STUDIES IN TWINS HAVE SUGGESTED A ROLE FOR ENVIRONMENTAL AND EPIGENETIC FACTORS, AS WELL AS GENETIC-EPIGENETIC INTERACTION. ACCORDINGLY, THERE IS EVIDENCE THAT DIFFERENCES IN DNA METHYLATION, HISTONE MODIFICATIONS, AND MIRNA PROFILING CAN BE FOUND IN LUPUS PATIENTS VERSUS NORMAL SUBJECTS. MOREOVER, IMPAIRED DNA METHYLATION ON THE INACTIVE X-CHROMOSOME WAS SUGGESTED TO EXPLAIN, AT LEAST IN PART, THE FEMALE PREVALENCE OF THE DISEASE. EPIGENETIC MARKERS MAY BE HELP IN FULFILLING THE UNMET NEEDS FOR SLE BY OFFERING NEW DIAGNOSTIC TOOLS, NEW BIOMARKERS FOR MONITORING DISEASE ACTIVITY, OR TO BETTER CHARACTERIZE PATIENTS WITH A SILENT CLINICAL DISEASE BUT WITH AN ACTIVE SEROLOGY. ANTI-DNA, ANTI-PHOSPHOLIPID, AND ANTI-RO/SSA AUTOANTIBODIES ARE THOUGHT TO BE PATHOGENIC FOR GLOMERULONEPHRITIS, RECURRENT THROMBOSIS AND MISCARRIAGES, AND NEONATAL LUPUS, RESPECTIVELY. HOWEVER, TISSUE DAMAGE OCCURS OCCASIONALLY OR, IN SOME PATIENTS, ONLY IN SPITE OF THE PERSISTENT PRESENCE OF THE ANTIBODIES. PRELIMINARY STUDIES SUGGEST THAT EPIGENETIC MECHANISMS MAY EXPLAIN WHY THE DAMAGE TAKES PLACE IN SOME PATIENTS ONLY OR AT A GIVEN TIME. 2016 4 6194 34 THE IMPACT OF PROTEIN ACETYLATION/DEACETYLATION ON SYSTEMIC LUPUS ERYTHEMATOSUS. SYSTEMIC LUPUS ERYTHEMATOSUS (SLE) IS A CHRONIC INFLAMMATORY AUTOIMMUNE DISEASE IN WHICH THE BODY'S IMMUNE SYSTEM MISTAKENLY ATTACKS HEALTHY CELLS. ALTHOUGH THE EXACT CAUSE OF SLE HAS NOT BEEN IDENTIFIED, IT IS CLEAR THAT BOTH GENETICS AND ENVIRONMENTAL FACTORS TRIGGER THE DISEASE. IDENTICAL TWINS HAVE A 24% CHANCE OF GETTING LUPUS DISEASE IF THE OTHER ONE IS AFFECTED. INTERNAL FACTORS SUCH AS FEMALE GENDER AND SEX HORMONES, THE MAJOR HISTOCOMPATIBILITY COMPLEX (MHC) LOCUS AND OTHER GENETIC POLYMORPHISMS HAVE BEEN SHOWN TO AFFECT SLE, AS WELL AS EXTERNAL, ENVIRONMENTAL INFLUENCES SUCH AS SUNLIGHT EXPOSURE, SMOKING, VITAMIN D DEFICIENCY, AND CERTAIN INFECTIONS. SEVERAL STUDIES HAVE REPORTED AND PROPOSED MULTIPLE ASSOCIATIONS BETWEEN THE ALTERATION OF THE EPIGENOME AND THE PATHOGENESIS OF AUTOIMMUNE DISEASE. EPIGENETIC FACTORS CONTRIBUTING TO SLE INCLUDE MICRORNAS, DNA METHYLATION STATUS, AND THE ACETYLATION/DEACETYLATION OF HISTONE PROTEINS. ADDITIONALLY, THE ACETYLATION OF NON-HISTONE PROTEINS CAN ALSO INFLUENCE CELLULAR FUNCTION. A BETTER UNDERSTANDING OF NON-GENOMIC FACTORS THAT REGULATE SLE WILL PROVIDE INSIGHT INTO THE MECHANISMS THAT INITIATE AND FACILITATE DISEASE AND ALSO CONTRIBUTE TO THE DEVELOPMENT OF NOVEL THERAPEUTICS THAT CAN SPECIFICALLY TARGET PATHOGENIC MOLECULAR PATHWAYS. 2018 5 1463 37 DISSECTING COMPLEX EPIGENETIC ALTERATIONS IN HUMAN LUPUS. SYSTEMIC LUPUS ERYTHEMATOSUS IS A CHRONIC RELAPSING AUTOIMMUNE DISEASE THAT PRIMARILY AFFLICTS WOMEN, AND BOTH A GENETIC PREDISPOSITION AND APPROPRIATE ENVIRONMENTAL EXPOSURES ARE REQUIRED FOR LUPUS TO DEVELOP AND FLARE. THE GENETIC REQUIREMENT IS EVIDENCED BY AN INCREASED CONCORDANCE IN IDENTICAL TWINS AND BY THE VALIDATION OF AT LEAST 35 SINGLE-NUCLEOTIDE POLYMORPHISMS PREDISPOSING PATIENTS TO LUPUS. GENES ALONE, THOUGH, ARE NOT ENOUGH. THE CONCORDANCE OF LUPUS IN IDENTICAL TWINS IS OFTEN INCOMPLETE, AND WHEN CONCORDANT, THE AGE OF ONSET IS USUALLY DIFFERENT. LUPUS IS ALSO NOT PRESENT AT BIRTH, BUT ONCE THE DISEASE DEVELOPS, IT TYPICALLY FOLLOWS A CHRONIC RELAPSING COURSE. THUS, GENES ALONE ARE INSUFFICIENT TO CAUSE HUMAN LUPUS, AND ADDITIONAL FACTORS ENCOUNTERED IN THE ENVIRONMENT AND OVER TIME ARE REQUIRED TO INITIATE THE DISEASE AND SUBSEQUENT FLARES. THE NATURE OF THE ENVIRONMENTAL CONTRIBUTION, THOUGH, AND THE MECHANISMS BY WHICH ENVIRONMENTAL AGENTS MODIFY THE IMMUNE RESPONSE TO CAUSE LUPUS ONSET AND FLARES IN GENETICALLY PREDISPOSED PEOPLE HAVE BEEN CONTROVERSIAL. REPORTS THAT THE LUPUS-INDUCING DRUGS PROCAINAMIDE AND HYDRALAZINE ARE EPIGENETIC MODIFIERS, THAT EPIGENETICALLY MODIFIED T CELLS ARE SUFFICIENT TO CAUSE LUPUS-LIKE AUTOIMMUNITY IN ANIMAL MODELS, AND THAT PATIENTS WITH ACTIVE LUPUS HAVE EPIGENETIC CHANGES SIMILAR TO THOSE CAUSED BY PROCAINAMIDE AND HYDRALAZINE HAVE PROMPTED A GROWING INTEREST IN HOW EPIGENETIC ALTERATIONS CONTRIBUTE TO THIS DISEASE. UNDERSTANDING HOW EPIGENETIC MECHANISMS MODIFY T CELLS TO CONTRIBUTE TO LUPUS REQUIRES AN UNDERSTANDING OF HOW EPIGENETIC MECHANISMS REGULATE GENE EXPRESSION. THE ROLES OF DNA METHYLATION, HISTONE MODIFICATIONS, AND MICRORNAS IN LUPUS PATHOGENESIS WILL BE REVIEWED HERE. 2013 6 3402 30 HOW DOES AGE DETERMINE THE DEVELOPMENT OF HUMAN IMMUNE-MEDIATED ARTHRITIS? DOES AGE SUBSTANTIALLY AFFECT THE EMERGENCE OF HUMAN IMMUNE-MEDIATED ARTHRITIS? CHILDREN DO NOT USUALLY DEVELOP IMMUNE-MEDIATED ARTICULAR INFLAMMATION DURING THEIR FIRST YEAR OF LIFE. IN PATIENTS WITH JUVENILE IDIOPATHIC ARTHRITIS, THIS APPARENT 'IMMUNE PRIVILEGE' DISINTEGRATES, AND CHRONIC INFLAMMATION IS ASSOCIATED WITH VARIABLE AUTOANTIBODY SIGNATURES AND PATTERNS OF DISEASE THAT RESEMBLE ADULT ARTHRITIS PHENOTYPES. NUMEROUS MECHANISMS MIGHT BE INVOLVED IN THIS SHIFT, INCLUDING GENETIC AND EPIGENETIC PREDISPOSING FACTORS, MATURATION OF THE IMMUNE SYSTEM WITH A PROGRESSIVE MODULATION OF PUTATIVE TOLEROGENIC CONTROLS, PARALLEL DEVELOPMENT OF MICROBIAL DYSBIOSIS, ACCUMULATION OF A PRO-INFLAMMATORY BURDEN DRIVEN BY ENVIRONMENTAL EXPOSURES (THE EXPOSOME) AND COMORBIDITY-RELATED DRIVERS. BY EXPLORING THESE MECHANISMS, WE EXPAND THE DISCUSSION OF THREE (NOT MUTUALLY EXCLUSIVE) HYPOTHESES ON HOW THESE FACTORS CAN CONTRIBUTE TO THE DIFFERENCES AND SIMILARITIES BETWEEN THE LOSS OF IMMUNE TOLERANCE IN CHILDREN AND THE DEVELOPMENT OF ESTABLISHED IMMUNE-MEDIATED ARTHRITIS IN ADULTS. THESE THREE HYPOTHESES RELATE TO A CRITICAL WINDOW IN GENETICS AND EPIGENETICS, IMMUNE MATURATION, AND THE ACCUMULATION OF BURDEN. THE VARIED MANIFESTATION OF THE UNDERLYING MECHANISMS AMONG INDIVIDUALS IS ONLY BEGINNING TO BE CLARIFIED, BUT THE ESTABLISHMENT OF A FRAMEWORK CAN FACILITATE THE DEVELOPMENT OF AN INTEGRATED UNDERSTANDING OF THE PATHOGENESIS OF ARTHRITIS ACROSS ALL AGES. 2022 7 5643 34 SEX AND AUTOIMMUNITY: PROPOSED MECHANISMS OF DISEASE ONSET AND SEVERITY. CHRONIC AUTOIMMUNE DISEASES AFFECT 5-10% OF THE POPULATION WORLDWIDE AND ARE LARGELY PREDOMINANT IN WOMEN. SEX HORMONE CHANGES HAVE BEEN WIDELY INVESTIGATED BASED ON CHANGES IN THE CLINICAL PHENOTYPES OBSERVED DURING PREGNANCY AND MENOPAUSE. IT IS KNOWN THAT FEMALES WITH AUTOIMMUNE DISEASES MANIFEST A HIGHER RATE OF CIRCULATING LEUKOCYTES WITH A SINGLE X CHROMOSOME, AND THERE HAVE BEEN SEVERAL REPORTS ON THE ROLE OF X CHROMOSOME GENE DOSAGE THROUGH INACTIVATION OR DUPLICATION IN AUTOIMMUNITY. HOWEVER, IT IS ALSO IMPORTANT NOT TO OVERLOOK MEN WITH AUTOIMMUNE DISEASES, WHO MIGHT MANIFEST A MORE FREQUENT LOSS OF THE Y CHROMOSOME IN CIRCULATING LEUKOCYTES. AREAS COVERED: IN THE PRESENT REVIEW, WE WILL DISCUSS THE CURRENT EVIDENCE SUPPORTING THE MECHANISMS OF FEMALE PREDOMINANCE IN RHEUMATIC DISEASES, BY DISCUSSING THE ROLE OF REPRODUCTIVE HISTORY, SEX HORMONES AND ABNORMALITIES RELATED TO THEM, CLINICAL DIFFERENCES BETWEEN MALE AND FEMALE PATIENTS, AND EPIGENETIC CHANGES THAT HAVE BEEN EVALUATED THROUGH TWIN STUDIES ON GENETIC AND ENVIRONMENTAL CHANGES IN RHEUMATIC PATIENTS. EXPERT OPINION: THE INFLUENCE OF SEX HORMONES AND CHROMOSOMES ON THE FUNCTION OF THE INNATE AND ADAPTIVE IMMUNE SYSTEMS NEEDS TO BE CLARIFIED, TO BETTER UNDERSTAND THE RISK OF AUTOIMMUNE DISEASES, EARLY DIAGNOSTIC TOOLS, AND THERAPEUTIC RESPONSE. 2019 8 2945 33 GENETIC AND EPIGENETIC BASIS OF PSORIASIS PATHOGENESIS. PSORIASIS IS A CHRONIC INFLAMMATORY SKIN DISEASE WHOSE PREVALENCE VARIES AMONG DIFFERENT POPULATIONS WORLDWIDE. IT IS A COMPLEX MULTI-FACTORIAL DISEASE AND THE EXACT ETIOLOGY IS LARGELY UNKNOWN. FAMILY BASED STUDIES HAVE INDICATED A GENETIC PREDISPOSITION; HOWEVER THEY CANNOT FULLY EXPLAIN THE DISEASE PATHOGENESIS. IN ADDITION TO GENETIC SUSCEPTIBILITY, ENVIRONMENTAL AS WELL AS GENDER AND AGE RELATED FACTORS WERE ALSO BEEN FOUND TO BE ASSOCIATED. RECENTLY, IMBALANCES IN EPIGENETIC NETWORKS ARE INDICATED TO BE CAUSATIVE ELEMENTS IN PSORIASIS. THE PRESENT KNOWLEDGE OF EPIGENETIC INVOLVEMENT, MAINLY THE DNA METHYLATION, CHROMATIN MODIFICATIONS AND MIRNA DEREGULATION IS SURVEYED HERE. AN INTEGRATED APPROACH CONSIDERING GENETIC AND EPIGENETIC ANOMALIES IN THE LIGHT OF IMMUNOLOGICAL NETWORK MAY EXPLORE THE PATHOGENESIS OF PSORIASIS. 2015 9 1719 29 DYSREGULATED MICRORNAS IN THE PATHOGENESIS OF SYSTEMIC LUPUS ERYTHEMATOSUS: A COMPREHENSIVE REVIEW. SYSTEMIC LUPUS ERYTHEMATOSUS IS A CHRONIC AUTOIMMUNE DISEASE OF WHICH CLINICAL PRESENTATION IS VASTLY HETEROGENEOUS, RANGING FROM MILD SKIN RASHES TO SEVERE RENAL DISEASES. TREATMENT GOAL OF THIS ILLNESS IS TO MINIMIZE DISEASE ACTIVITY AND PREVENT FURTHER ORGAN DAMAGE. IN RECENT YEARS, MUCH RESEARCH HAS BEEN DONE ON THE EPIGENETIC ASPECTS OF SLE PATHOGENESIS, FOR AMONG THE VARIOUS FACTORS KNOWN TO CONTRIBUTE TO THE PATHOGENIC PROCESS, EPIGENETIC FACTORS, ESPECIALLY MICRORNAS, BEAR THE MOST THERAPEUTIC POTENTIAL THAT CAN BE ALTERED UNLIKE CONGENITAL GENETIC FACTORS. THIS ARTICLE REVIEWS AND UPDATES WHAT HAS BEEN DISCOVERED SO FAR ABOUT THE PATHOGENESIS OF LUPUS, WHILE FOCUSING ON THE DYSREGULATION OF MICRORNAS IN LUPUS PATIENTS IN COMPARISON TO HEALTHY CONTROLS ALONG WITH THE POTENTIALLY PATHOGENIC ROLES OF THE MICRORNAS COMMONLY REPORTED TO BE EITHER UPREGULATED OR DOWNREGULATED. FURTHERMORE, THIS REVIEW INCLUDES MICRORNAS OF WHICH RESULTS ARE CONTROVERSIAL, SUGGESTING POSSIBLE EXPLANATIONS FOR SUCH DISCREPANCIES AND DIRECTIONS FOR FUTURE RESEARCH. MOREOVER, WE AIMED TO EMPHASIZE THE POINT THAT HAD BEEN OVERLOOKED SO FAR IN STUDIES REGARDING MICRORNA EXPRESSION LEVELS; THAT IS, WHICH SPECIMEN WAS USED TO ASSESS THE DYSREGULATION OF MICRORNAS. TO OUR SURPRISE, A VAST NUMBER OF STUDIES HAVE NOT CONSIDERED THIS FACTOR AND HAVE ANALYZED THE POTENTIAL ROLE OF MICRORNAS IN GENERAL. DESPITE EXTENSIVE INVESTIGATIONS DONE ON MICRORNA LEVELS, THEIR SIGNIFICANCE AND POTENTIAL ROLE REMAIN A MYSTERY, WHICH CALLS FOR FURTHER STUDIES ON THIS PARTICULAR SUBJECT IN REGARD OF WHICH SPECIMEN IS USED FOR ASSESSMENT. 2023 10 2404 35 EPIGENETIC RESEARCH IN MULTIPLE SCLEROSIS: PROGRESS, CHALLENGES, AND OPPORTUNITIES. MULTIPLE SCLEROSIS (MS) IS A CHRONIC INFLAMMATORY AND DEMYELINATING DISEASE OF THE CENTRAL NERVOUS SYSTEM. MS LIKELY RESULTS FROM A COMPLEX INTERPLAY BETWEEN PREDISPOSING CAUSAL GENE VARIANTS (THE STRONGEST INFLUENCE COMING FROM HLA CLASS II LOCUS) AND ENVIRONMENTAL RISK FACTORS SUCH AS SMOKING, INFECTIOUS MONONUCLEOSIS, AND LACK OF SUN EXPOSURE/VITAMIN D. HOWEVER, LITTLE IS KNOWN ABOUT THE MECHANISMS UNDERLYING MS DEVELOPMENT AND PROGRESSION. MOREOVER, THE CLINICAL HETEROGENEITY AND VARIABLE RESPONSE TO TREATMENT REPRESENT ADDITIONAL CHALLENGES TO A COMPREHENSIVE UNDERSTANDING AND EFFICIENT TREATMENT OF DISEASE. EPIGENETIC PROCESSES, SUCH AS DNA METHYLATION AND HISTONE POSTTRANSLATIONAL MODIFICATIONS, INTEGRATE INFLUENCES FROM THE GENES AND THE ENVIRONMENT TO REGULATE GENE EXPRESSION ACCORDINGLY. STUDYING EPIGENETIC MODIFICATIONS, WHICH ARE STABLE AND REVERSIBLE, MAY PROVIDE AN ALTERNATIVE APPROACH TO BETTER UNDERSTAND AND MANAGE DISEASE. WE HERE AIM TO REVIEW FINDINGS FROM EPIGENETIC STUDIES IN MS AND FURTHER DISCUSS THE CHALLENGES AND CLINICAL OPPORTUNITIES ARISING FROM EPIGENETIC RESEARCH, MANY OF WHICH APPLY TO OTHER DISEASES WITH SIMILAR COMPLEX ETIOLOGY. A GROWING BODY OF EVIDENCE SUPPORTS A ROLE OF EPIGENETIC PROCESSES IN THE MECHANISMS UNDERLYING IMMUNE PATHOGENESIS AND NERVOUS SYSTEM DYSFUNCTION IN MS. HOWEVER, DISPARITIES BETWEEN STUDIES SHED LIGHT ON THE NEED TO CONSIDER POSSIBLE CONFOUNDERS AND METHODOLOGICAL LIMITATIONS FOR A BETTER INTERPRETATION OF THE DATA. NEVERTHELESS, TRANSLATIONAL USE OF EPIGENETICS MIGHT OFFER NEW OPPORTUNITIES IN EPIGENETIC-BASED DIAGNOSTICS AND THERAPEUTIC TOOLS FOR A PERSONALIZED CARE OF MS PATIENTS. 2017 11 738 32 CANCER SUSCEPTIBILITY: EPIGENETIC MANIFESTATION OF ENVIRONMENTAL EXPOSURES. CANCER IS A DISEASE THAT RESULTS FROM BOTH GENETIC AND EPIGENETIC CHANGES. DISCORDANT PHENOTYPES AND VARYING INCIDENCES OF COMPLEX DISEASES SUCH AS CANCER IN MONOZYGOTIC TWINS AS WELL AS GENETICALLY IDENTICAL LABORATORY ANIMALS HAVE LONG BEEN ATTRIBUTED TO DIFFERENCES IN ENVIRONMENTAL EXPOSURES. ACCUMULATING EVIDENCE INDICATES, HOWEVER, THAT DISPARITIES IN GENE EXPRESSION RESULTING FROM VARIABLE MODIFICATIONS IN DNA METHYLATION AND CHROMATIN STRUCTURE IN RESPONSE TO THE ENVIRONMENT ALSO PLAY A ROLE IN DIFFERENTIAL SUSCEPTIBILITY TO DISEASE. DESPITE A GROWING CONSENSUS ON THE IMPORTANCE OF EPIGENETICS IN THE ETIOLOGY OF CHRONIC HUMAN DISEASES, THE GENES MOST PRONE TO EPIGENETIC DYSREGULATION ARE INCOMPLETELY DEFINED. MOREOVER, NEITHER THE ENVIRONMENTAL AGENTS MOST STRONGLY AFFECTING THE EPIGENOME NOR THE CRITICAL WINDOWS OF VULNERABILITY TO ENVIRONMENTALLY INDUCED EPIGENETIC ALTERATIONS ARE ADEQUATELY CHARACTERIZED. THESE MAJOR DEFICITS IN KNOWLEDGE MARKEDLY IMPAIR OUR ABILITY TO UNDERSTAND FULLY THE ETIOLOGY OF CANCER AND THE IMPORTANCE OF THE EPIGENOME IN DIAGNOSING AND PREVENTING THIS DEVASTATING DISEASE. 2007 12 2512 41 EPIGENETICS AND PRIMARY BILIARY CIRRHOSIS: A COMPREHENSIVE REVIEW AND IMPLICATIONS FOR AUTOIMMUNITY. PRIMARY BILIARY CIRRHOSIS (PBC) IS A CHRONIC INFLAMMATORY AUTOIMMUNE DISEASE THAT DEVELOPS BASED UPON THE INTERACTION OF GENETIC AND ENVIRONMENTAL FACTORS. RECENT GENOME-WIDE ASSOCIATION STUDIES (GWAS) HAVE IDENTIFIED DOZENS OF PREDISPOSING VARIANTS INCLUDING HLA, IL12A, AND CTLA4 BUT HAVE BEEN DISAPPOINTED IN IDENTIFYING A "SMOKING GUN." THESE DISCOVERIES HIGHLIGHT THE IMPORTANCE OF THE GENETIC BACKGROUND INVOLVED IN IMMUNOLOGICAL DYSREGULATION. ALTHOUGH CONCORDANCE RATE OF PBC IN MONOZYGOTIC (MZ) TWINS IS AMONG THE HIGHEST REPORTED IN AUTOIMMUNE DISORDERS, INCOMPLETE DISEASE CONCORDANCE IN TWINS ASSOCIATED WITH DIFFERENTIALLY EXPRESSED GENES HAS BEEN DEMONSTRATED. HOWEVER, LITTLE IS UNDERSTOOD ABOUT HOW ENVIRONMENTAL ASPECTS CONTRIBUTE TO THE DISEASE AND WHY MIDDLE-AGED WOMEN ARE MORE SUSCEPTIBLE. AS A RESULT, EPIGENETIC FACTORS, WHICH CONVERT SIGNALS INDICATING ENVIRONMENTAL CHANGES INTO DYNAMIC AND HERITABLE ALTERATIONS OF TRANSCRIPTIONAL POTENTIAL, ARE GETTING INCREASED ATTENTION BY RESEARCHERS IN BOTH BASIC AND CLINICAL STUDIES. AMONG EPIGENETIC MECHANISMS, THE INSTABILITY AND SKEWED GENE EXPRESSION IN THE X CHROMOSOME MAY ACCOUNT FOR THE FEMALE PREPONDERANCE IN PBC. IN ADDITION, TRANSCRIPTIONAL REGULATION OF HISTONE MODIFICATION AND DNA METHYLATION UNDERSCORES POTENTIAL INVOLVEMENT IN DISEASE PATHOGENESIS. HIGH-THROUGHPUT TECHNIQUES ARE BEING USED TO IDENTIFY EPIGENETIC REGULATORS. IN THIS REVIEW, WE ATTEMPT TO OUTLINE RECENT PROGRESS REGARDING EPIGENETICS IN PBC AND OTHER AUTOIMMUNE DISEASES. 2016 13 6275 34 THE PATHOGENESIS OF SYSTEMIC LUPUS ERYTHEMATOSUS: HARNESSING BIG DATA TO UNDERSTAND THE MOLECULAR BASIS OF LUPUS. SYSTEMIC LUPUS ERYTHEMATOSUS (SLE) IS A CHRONIC, SYSTEMIC AUTOIMMUNE DISEASE THAT CAUSES DAMAGE TO MULTIPLE ORGAN SYSTEMS. DESPITE DECADES OF RESEARCH AND AVAILABLE MURINE MODELS THAT CAPTURE SOME ASPECTS OF THE HUMAN DISEASE, NEW TREATMENTS FOR SLE LAG BEHIND OTHER AUTOIMMUNE DISEASES SUCH AS RHEUMATOID ARTHRITIS AND CROHN'S DISEASE. BIG DATA GENOMIC ASSAYS HAVE TRANSFORMED OUR UNDERSTANDING OF SLE BY PROVIDING IMPORTANT INSIGHTS INTO THE MOLECULAR HETEROGENEITY OF THIS MULTIGENIC DISEASE. GENE WIDE ASSOCIATION STUDIES HAVE DEMONSTRATED MORE THAN 100 RISK LOCI, SUPPORTING A MODEL OF MULTIPLE GENETIC HITS INCREASING SLE RISK IN A NON-LINEAR FASHION, AND PROVIDING EVIDENCE OF ANCESTRAL DIVERSITY IN SUSCEPTIBILITY LOCI. EPIGENETIC STUDIES TO DETERMINE THE ROLE OF METHYLATION, ACETYLATION AND NON-CODING RNAS HAVE PROVIDED NEW UNDERSTANDING OF THE MODULATION OF GENE EXPRESSION IN SLE PATIENTS AND IDENTIFIED NEW DRUG TARGETS AND BIOMARKERS FOR SLE. GENE EXPRESSION PROFILING HAS LED TO A GREATER UNDERSTANDING OF THE ROLE OF MYELOID CELLS IN THE PATHOGENESIS OF SLE, CONFIRMED ROLES FOR T AND B CELLS IN SLE, PROMOTED CLINICAL TRIALS BASED ON THE PROMINENT INTERFERON SIGNATURE FOUND IN SLE PATIENTS, AND IDENTIFIED CANDIDATE BIOMARKERS AND CELLULAR SIGNATURES TO FURTHER DRUG DEVELOPMENT AND DRUG REPURPOSING. GENE EXPRESSION STUDIES ARE ADVANCING OUR UNDERSTANDING OF THE UNDERLYING MOLECULAR HETEROGENEITY IN SLE AND PROVIDING HOPE THAT PATIENT STRATIFICATION WILL EXPEDITE NEW THERAPIES BASED ON PERSONAL MOLECULAR SIGNATURES. ALTHOUGH BIG DATA ANALYSES PRESENT UNIQUE INTERPRETATION CHALLENGES, BOTH COMPUTATIONALLY AND BIOLOGICALLY, ADVANCES IN MACHINE LEARNING APPLICATIONS MAY FACILITATE THE ABILITY TO PREDICT CHANGES IN SLE DISEASE ACTIVITY AND OPTIMIZE THERAPEUTIC STRATEGIES. 2020 14 2294 37 EPIGENETIC REGULATION IN THE PATHOGENESIS OF SJOGREN SYNDROME AND RHEUMATOID ARTHRITIS. AUTOIMMUNE RHEUMATIC DISEASES, SUCH AS SJOGREN SYNDROME (SS) AND RHEUMATOID ARTHRITIS (RA), ARE CHARACTERIZED BY CHRONIC INFLAMMATION AND AUTOIMMUNITY, WHICH CAUSE JOINT TISSUE DAMAGE AND DESTRUCTION BY TRIGGERING REDUCED MOBILITY AND DEBILITATION IN PATIENTS WITH THESE DISEASES. INITIATION AND MAINTENANCE OF CHRONIC INFLAMMATORY STAGES ACCOUNT FOR SEVERAL MECHANISMS THAT INVOLVE IMMUNE CELLS AS KEY PLAYERS AND THE INTERACTION OF THE IMMUNE CELLS WITH OTHER TISSUES. INDEED, THE OVERLAPPING OF CERTAIN CLINICAL AND SEROLOGIC MANIFESTATIONS BETWEEN SS AND RA MAY INDICATE THAT NUMEROUS IMMUNOLOGIC-RELATED MECHANISMS ARE INVOLVED IN THE PHYSIOPATHOLOGY OF BOTH THESE DISEASES. IT IS WIDELY ACCEPTED THAT EPIGENETIC PATHWAYS PLAY AN ESSENTIAL ROLE IN THE DEVELOPMENT AND FUNCTION OF THE IMMUNE SYSTEM. ALTHOUGH MANY PUBLISHED STUDIES HAVE ATTEMPTED TO ELUCIDATE THE RELATION BETWEEN EPIGENETIC MODIFICATIONS (E.G. DNA METHYLATION, HISTONE POST-TRANSLATIONAL MODIFICATIONS, MIRNAS) AND AUTOIMMUNE DISORDERS, THE CONTRIBUTION OF EPIGENETIC REGULATION TO THE PATHOGENESIS OF SS AND RA IS AT PRESENT POORLY UNDERSTOOD. THIS REVIEW ATTEMPTS TO SHED LIGHT FROM A CRITICAL POINT OF VIEW ON THE IDENTIFICATION OF THE MOST RELEVANT EPIGENETIC MECHANISMS RELATED TO RA AND SS BY EXPLAINING INTRICATE REGULATORY PROCESSES AND PHENOTYPIC FEATURES OF BOTH AUTOIMMUNE DISEASES. MOREOVER, WE POINT OUT SOME EPIGENETIC MARKERS WHICH CAN BE USED TO MONITOR THE INFLAMMATION STATUS AND THE DYSREGULATED IMMUNITY IN SS AND RA. FINALLY, WE DISCUSS THE INCONVENIENCE OF USING EPIGENETIC DATA OBTAINED FROM BULK IMMUNE CELL POPULATIONS INSTEAD SPECIFIC IMMUNE CELL SUBPOPULATIONS. 2019 15 6791 28 [DOES THE NUMBER OF PATIENTS WITH AUTOIMMUNE DISORDERS AND THE FREQUENCY OF AUTOIMMUNE DISEASES INCREASE?]. AUTOIMMUNE DISEASES GENERALLY BELONG TO THE RARE DISEASES, HOWEVER, SOME OF THEM ARE FREQUENT IN THE POPULATION. IN THE PRESENT WORK THE AUTHORS ANALYSE WHETHER CAN ANY INCREASE BE OBSERVED IN THE NUMBER OF PATIENTS SUFFERING FROM AUTOIMMUNE DISEASES AND WHETHER DO THE FREQUENCY OF CERTAIN AUTOIMMUNE DISORDERS INCREASE. DUE MAINLY TO EPIGENETIC FACTORS THE INCIDENCE OF AUTOIMMUNE DISEASES ARE INCREASING, THEREFORE THERE ARE MORE PATIENTS RECOGNISED WITH PARTICULAR DISORDERS. ON THE OTHER HAND THE INCIDENCE IS INCREASED BY IMPROVING DIAGNOSTIC POSSIBILITIES, BY THE USE OF MORE SPECIFIC AND SENSITIVE CLASSIFICATION CRITERIA AND MORE SOPHISTICATED LABORATORY TESTS, RESULTED IN THE RECOGNITION OF MILDER AND ATYPICAL DISEASE VARIANTS AS WELL. THE PREVALENCE IS ALSO INCREASING IN CONSEQUENCE OF NOVEL IMMUNE SUPPRESSIVE THERAPEUTIC POSSIBILITIES AND THE CONSEQUENT IMPROVEMENT OF SURVIVAL IN THE MOST OF THESE DISEASES. BESIDES, MORE AND MORE DISEASES HAVE BEEN REVEALED TO HAVE AUTOIMMUNE BACKGROUND, AND LOT OF NEW AUTOIMMUNE SYNDROMES, DISEASES HAVE BEEN CHARACTERISED RECENTLY. THIS INCREASES THE NUMBER OF THE KNOWN AUTOIMMUNE RHEUMATIC DISORDERS WITH A CONSEQUENT INCREASE IN THE NUMBER OF AUTOIMMUNE PATIENTS. ASSIGNED TO THE INCREASING NUMBER OF VARIABLE CHRONIC AUTOIMMUNE DISORDERS, AND THE INCREASING NUMBER OF DISABLED PATIENTS WITH SUCH DISEASES INCREASING MEDICAL AND SOCIAL ATTENTION HAS TO BE FOCUSED ON. 2007 16 398 31 AN UPDATE ON GENETIC SUSCEPTIBILITY IN LUPUS NEPHRITIS. SYSTEMIC LUPUS ERYTHEMATOSUS (SLE) IS A CHRONIC AUTOIMMUNE DISEASE CHARACTERIZED BY MULTIPLE SYSTEM INVOLVEMENT AND POSITIVE SERUM AUTOANTIBODIES. LUPUS NEPHRITIS (LN) IS THE MOST COMMON AND SERIOUS COMPLICATION OF SLE, AND IT IS THE MAIN CAUSE OF DEATH IN PATIENTS WITH SLE. ABNORMALITIES IN THE IMMUNE SYSTEM LEAD TO LN AND INVOLVE A VARIETY OF CELLS (T CELLS, B CELLS, MACROPHAGES, NK CELLS, ETC.), CYTOKINES (INTERLEUKIN, TUMOR NECROSIS FACTOR ALPHA, ETC.) AND THEIR RELATED PATHWAYS. PREVIOUS STUDIES HAVE SHOWN THAT THE INTERACTIONS OF GENETIC, EPIGENETIC AND ENVIRONMENTAL FACTORS CONTRIBUTE TO THE PATHOGENESIS AND DEVELOPMENT OF LN. IN RECENT YEARS, ONE GENOME-WIDE ASSOCIATION STUDY (GWAS) AND A NUMBER OF GENE ASSOCIATION STUDIES HAVE EXPLORED THE SUSCEPTIBILITY GENES OF LN, INCLUDING IMMUNIZATION-, INFLAMMATION-, ADHESION- AND OTHER PATHWAY-RELATED GENES. THESE GENES PARTICIPATE IN OR SUGGEST THE PATHOGENESIS AND PROGRESSION OF LN. IN THIS REVIEW, WE SUMMARIZE THE GENETIC SUSCEPTIBILITY OF LN AND DISCUSS THE POSSIBLE MECHANISM UNDERLYING THE SUSCEPTIBILITY GENES OF LN. 2020 17 2027 41 EPIGENETIC CHANGES IN CHRONIC INFLAMMATORY DISEASES. THE NUMBER OF PEOPLE DIAGNOSED WITH CHRONIC INFLAMMATORY DISEASES HAS INCREASED NOTEWORTHY IN THE LAST 40 YEARS. SPONDYLOARTHRITIS (SPA), INFLAMMATORY BOWEL DISEASES (IBD), AND PSORIASIS ARE THE MOST FREQUENT CHRONIC INFLAMMATORY DISEASES, RESULTING FROM A COMBINATION OF GENETIC PREDISPOSITION AND ENVIRONMENTAL FACTORS. EPIGENETIC MODIFICATIONS INCLUDE DNA METHYLATION, HISTONE MODIFICATIONS, AND SMALL AND LONG NONCODING RNAS. THEY ARE INFLUENCED BY ENVIRONMENTAL EXPOSURE, LIFE-STYLE, AND AGING AND HAVE RECENTLY BEEN SHOWN TO BE ALTERED IN MANY COMPLEX DISEASES INCLUDING INFLAMMATORY DISEASES. WHILE EPIGENETIC MODIFICATIONS HAVE BEEN WELL CHARACTERIZED IN OTHER DISEASES SUCH AS CANCER AND AUTOIMMUNE DISEASES, KNOWLEDGE ON CHANGES IN INFLAMMATORY DISEASES IS LAGGING BEHIND WITH SOME DISEASE-SPECIFIC DIFFERENCES. WHILE THE DNA METHYLATION PROFILE OF DIFFERENT CELL TYPES IN PATIENTS WITH IBD HAS BEEN RELATIVELY WELL DESCRIBED, LESS IS KNOWN ON CHANGES IMPLICATED IN PSORIASIS, AND NO SYSTEMATIC GENOME-WIDE STUDIES HAVE SO FAR BEEN PERFORMED IN SPA. IN THIS CHAPTER, WE REVIEW IN DETAIL THE REPORTED CHANGES IN PATTERNS OF DNA METHYLATION AND POSTTRANSLATIONAL HISTONE MODIFICATIONS IN CHRONIC INFLAMMATORY DISEASES HIGHLIGHTING POTENTIAL CONNECTIONS BETWEEN DISEASE-ASSOCIATED PATHOPHYSIOLOGICAL CHANGES SUCH AS THE DYSBIOSIS OF THE MICROBIOME OR GENETIC VARIATIONS ASSOCIATED WITH DISEASE SUSCEPTIBILITY AND THE EPIGENOME. WE ALSO DISCUSS IMPORTANT PARAMETERS OF MEANINGFUL EPIGENETIC STUDIES SUCH AS THE USE OF WELL DEFINED, DISEASE-RELEVANT CELL POPULATIONS, AND ELUDE ON THE POTENTIAL FUTURE OF ENGINEERING OF THE EPIGENOME IN INFLAMMATORY DISEASES. 2017 18 3039 28 GENOME ENGINEERING FOR PERSONALIZED ARTHRITIS THERAPEUTICS. ARTHRITIS REPRESENTS A FAMILY OF COMPLEX JOINT PATHOLOGIES RESPONSIBLE FOR THE MAJORITY OF MUSCULOSKELETAL CONDITIONS. NEARLY ALL DISEASES WITHIN THIS FAMILY, INCLUDING OSTEOARTHRITIS, RHEUMATOID ARTHRITIS, AND JUVENILE IDIOPATHIC ARTHRITIS, ARE CHRONIC CONDITIONS WITH FEW OR NO DISEASE-MODIFYING THERAPEUTICS AVAILABLE. ADVANCES IN GENOME ENGINEERING TECHNOLOGY, MOST RECENTLY WITH CRISPR-CAS9, HAVE REVOLUTIONIZED OUR ABILITY TO INTERROGATE AND VALIDATE GENETIC AND EPIGENETIC ELEMENTS ASSOCIATED WITH CHRONIC DISEASES SUCH AS ARTHRITIS. THESE TECHNOLOGIES, TOGETHER WITH CELL REPROGRAMMING METHODS, INCLUDING THE USE OF INDUCED PLURIPOTENT STEM CELLS, PROVIDE A PLATFORM FOR HUMAN DISEASE MODELING. WE SUMMARIZE NEW EVIDENCE FROM GENOME-WIDE ASSOCIATION STUDIES AND GENOMICS THAT SUBSTANTIATES A GENETIC BASIS FOR ARTHRITIS PATHOGENESIS. WE ALSO REVIEW THE POTENTIAL CONTRIBUTIONS OF GENOME ENGINEERING IN THE DEVELOPMENT OF NEW ARTHRITIS THERAPEUTICS. 2017 19 4844 31 ONE YEAR IN REVIEW 2019: PATHOGENESIS OF RHEUMATOID ARTHRITIS. RHEUMATOID ARTHRITIS (RA) IS A CHRONIC INFLAMMATORY AUTOIMMUNE DISEASE INFLUENCED BY BOTH GENETIC AND ENVIRONMENTAL FACTORS. OVER THE LAST FEW YEARS, PARTICULAR ATTENTION HAS BEEN GIVEN TO NOVEL GENES AND TO THE CLOSE INTERACTION BETWEEN GENETIC FACTORS AND EPIGENETIC MECHANISMS. RESEARCH HAS ALSO FOCUSED ON THE INFLUENCE OF ENVIRONMENTAL FACTORS ON DISEASE DEVELOPMENT, AND ON NEW MECHANISMS OF THE INNATE AND ADAPTIVE IMMUNE SYSTEM THAT CAN INFLUENCE THE DIFFERENT STAGES OF RA. HOWEVER, THERE ARE STILL SEVERAL ASPECTS OF THE DISEASE THAT NEED FURTHER INVESTIGATION. SHEDDING SOME LIGHT ON THE DIFFERENT ASPECTS OF RA PATHOGENESIS WILL HELP TO IMPROVE THE CURRENT DIAGNOSTIC TOOLS AND TO IDENTIFY NEW TARGETS FOR THE DEVELOPMENT OF DISEASE-MODIFYING THERAPIES. THUS, IN THIS REVIEW WE SUMMARISE THE NEW INSIGHTS IN RA PATHOGENESIS, RESULTING FROM LITERATURE RESEARCH DATA PUBLISHED IN THE LAST YEAR. 2019 20 2988 23 GENETIC FACTORS AND SYSTEMIC SCLEROSIS. SYSTEMIC SCLEROSIS (SSC) IS A RARE CONNECTIVE TISSUE DISEASE OF UNKNOWN ETIOLOGY CHARACTERIZED BY CHRONIC INFLAMMATION AND FIBROSIS OF THE SKIN, VASCULAR ABNORMALITIES, AND VARIABLE INVOLVEMENT OF ORGANS INCLUDING KIDNEYS, GASTROINTESTINAL TRACT, HEART, AND LUNGS. SSC SHOWS A COMPLEX ETIOLOGY IN WHICH BOTH ENVIRONMENTAL AND GENETIC FACTORS SEEM TO INFLUENCE THE ONSET AND OUTCOME OF THE DISEASE. WE PROVIDE AN EXTENSIVE OVERVIEW OF THE GENETIC FACTORS AND EPIGENETIC MODIFICATIONS AND WHAT THEIR KNOWLEDGE HAS REVEALED IN TERMS OF ETIOPATHOGENESIS OF SSC. 2016