1 3011 102 GENETICS AND EPIGENETICS IN THE FIBROGENIC EVOLUTION OF CHRONIC LIVER DISEASES. RECENT YEARS HAVE SEEN UNPRECEDENTED PROGRESS IN THE IDENTIFICATION AND CHARACTERIZATION OF GENETIC INFORMATION RELATED TO CHRONIC LIVER DISEASES (CLDS). HOWEVER, DESPITE THE CONCEPTUAL BENEFIT IN EARLY RECOGNITION OF AT-RISK POPULATIONS AMENABLE TO PRE-EMPTIVE TREATMENT AND/OR SURVEILLANCE STRATEGIES, RECENT GENOMIC RESEARCH IN THE FIELD HAS PLACED FOCUS ON UNRAVELLING THE GENETIC ARCHITECTURE OF DISEASE SUSCEPTIBILITY, WHILE DATA ON GENETIC MARKERS ANTICIPATING AN ACCELERATED FIBROGENESIS IN AN INDIVIDUAL ARE STILL LIMITED. LIKEWISE, SEQUENCE VARIATION ASSIGNING RAPID FIBROGENIC EVOLUTION COMMON TO CLDS IRRESPECTIVE OF ETIOLOGY ARE POORLY DEFINED ASIDE FROM PNPLA3 (ADIPONUTRIN) AS A PROMINENT EXCEPTION. THE EMERGING FIELD OF EPIGENETICS IN HEPATOLOGY HAS MOSTLY BEEN STUDIED UNDER THE PERSPECTIVE OF GENE REGULATION, LESS SO AS A HERITABLE ALTERATION IN GENE ACTIVITY. IN THIS ARTICLE WE WILL CRITICALLY DISCUSS RECENT FINDINGS IN GENOMIC HEPATOLOGY WITH SPECIAL FOCUS ON THE (EPI)GENETIC CONTRIBUTION TO THE FIBROGENIC EVOLUTION OF CLDS. 2011 2 2545 27 EPIGENETICS IN LIVER FIBROSIS: COULD HDACS BE A THERAPEUTIC TARGET? CHRONIC LIVER DISEASES (CLD) REPRESENT A WORLDWIDE HEALTH PROBLEM. WHILE CLDS MAY HAVE DIVERSE ETIOLOGIES, A COMMON PATHOGENIC DENOMINATOR IS THE PRESENCE OF LIVER FIBROSIS. CIRRHOSIS, THE END-STAGE OF CLD, IS CHARACTERIZED BY EXTENSIVE FIBROSIS AND IS MARKEDLY ASSOCIATED WITH THE DEVELOPMENT OF HEPATOCELLULAR CARCINOMA. THE MOST IMPORTANT EVENT IN HEPATIC FIBROGENESIS IS THE ACTIVATION OF HEPATIC STELLATE CELLS (HSC) FOLLOWING LIVER INJURY. ACTIVATED HSCS ACQUIRE A MYOFIBROBLAST-LIKE PHENOTYPE BECOMING PROLIFERATIVE, FIBROGENIC, AND CONTRACTILE CELLS. WHILE TRANSIENT ACTIVATION OF HSCS IS PART OF THE PHYSIOLOGICAL MECHANISMS OF TISSUE REPAIR, PROTRACTED ACTIVATION OF A WOUND HEALING REACTION LEADS TO ORGAN FIBROSIS. THE PHENOTYPIC CHANGES OF ACTIVATED HSCS INVOLVE EPIGENETIC MECHANISMS MEDIATED BY NON-CODING RNAS (NCRNA) AS WELL AS BY CHANGES IN DNA METHYLATION AND HISTONE MODIFICATIONS. DURING CLD THESE EPIGENETIC MECHANISMS BECOME DEREGULATED, WITH ALTERATIONS IN THE EXPRESSION AND ACTIVITY OF EPIGENETIC MODULATORS. HERE WE PROVIDE AN OVERVIEW OF THE EPIGENETIC ALTERATIONS INVOLVED IN FIBROGENIC HSCS TRANSDIFFERENTIATION WITH PARTICULAR FOCUS ON HISTONES ACETYLATION CHANGES. WE ALSO DISCUSS RECENT STUDIES SUPPORTING THE PROMISING THERAPEUTIC POTENTIAL OF HISTONE DEACETYLASE INHIBITORS IN LIVER FIBROSIS. 2020 3 1354 33 DEVELOPMENT AND REGRESSION OF CIRRHOSIS. LIVER CIRRHOSIS IS THE ULTIMATE CONSEQUENCE OF THE WOUND HEALING REACTION SUBSEQUENT TO A CHRONIC INJURY, WHICH LEADS TO A COMPLETE DERANGEMENT OF THE NORMAL HEPATIC LOBULAR AND VASCULAR ARCHITECTURE. CIRRHOSIS IS CHARACTERIZED BY PATTERNS OF EVOLUTION DEPENDING ON THE CAUSATIVE AGENT AND A SERIES OF COMPLEX UNDERLINING MECHANISMS IN WHICH NEO-ANGIOGENESIS AND NECRO-INFLAMMATION PLAY A KEY ROLE. THE IMPORTANCE OF THE DIFFERENT CELL TYPES INVOLVED AND OF THE EXTRACELLULAR MATRIX COMPOSITION AS WELL AS THE ROLE OF INNATE IMMUNITY, BACTERIAL TRANSLOCATION AND OXIDATIVE STRESS ARE ALSO EMERGING. A VARIABLE DEGREE OF REGRESSION OF FIBROSIS AND EVEN CIRRHOSIS HAS BEEN DESCRIBED, IN EXPERIMENTAL MODELS, AFTER SUSPENSION OF THE LIVER DISEASE CAUSATIVE AGENT. AS SOME INDIVIDUAL FEATURES INFLUENCE THE RATE OF FIBROSIS PROGRESSION, GENETIC AND EPIGENETIC FACTORS ARE LIKELY TO INFLUENCE FIBROSIS REGRESSION. KEY MESSAGES: THERE IS INCREASING AWARENESS THAT CIRRHOSIS IS NOT A STATIC CONDITION BUT A DYNAMIC PROCESS. CURRENT SEMI-QUANTITATIVE SCORES AND CLINICAL CLASSIFICATIONS ARE INACCURATE AND UNABLE TO IDENTIFY THE DIFFERENT PHASES OF EVOLUTION OF THE ADVANCED STAGES OF CHRONIC LIVER DISEASES (CLDS). THE INCREASING AVAILABILITY OF EFFECTIVE ETIOLOGY-DRIVEN THERAPEUTIC OPTIONS FOR CLDS MAKES REVERSION OF CIRRHOSIS A MORE POSSIBLE PROSPECTIVE. HOWEVER, THE REMOVAL OF THE CAUSING AGENT, DEPENDING ON THE STAGE OF THE DISEASE, DOES NOT NECESSARILY ELIMINATE THE RISK OF DISEASE PROGRESSION, DECOMPENSATION AND DEVELOPMENT OF HEPATOCELLULAR CARCINOMA. ALSO, THE NON-INVASIVE MARKERS CURRENTLY VALIDATED FOR THE ASSESSMENT OF FIBROSIS ARE NOT SUITABLE FOR AN EFFECTIVE EVALUATION OF FIBROSIS REGRESSION. CONCLUSIONS: THERE IS A CRITICAL NEED OF A SYSTEM THAT WOULD BE ABLE TO MORE ACCURATELY DESCRIBE THE DYNAMIC DEVELOPMENT OF CIRRHOSIS AND THE IMPACT OF TISSUE FIBROSIS, NEO-ANGIOGENESIS, NECRO-INFLAMMATION AND ATTEMPTED REGENERATION ON ITS EVOLUTION. EFFECTIVE TREATMENT OF CLD CAN LEAD TO A VARIABLE DEGREE OF FIBROSIS REGRESSION. NEW MARKERS ABLE TO EVALUATE THIS PROCESS WILL NEED TO BE DETECTED AND VALIDATED. 2016 4 4108 14 MECHANISMS AND DISEASE CONSEQUENCES OF NONALCOHOLIC FATTY LIVER DISEASE. NONALCOHOLIC FATTY LIVER DISEASE (NAFLD) IS THE LEADING CHRONIC LIVER DISEASE WORLDWIDE. ITS MORE ADVANCED SUBTYPE, NONALCOHOLIC STEATOHEPATITIS (NASH), CONNOTES PROGRESSIVE LIVER INJURY THAT CAN LEAD TO CIRRHOSIS AND HEPATOCELLULAR CARCINOMA. HERE WE PROVIDE AN IN-DEPTH DISCUSSION OF THE UNDERLYING PATHOGENETIC MECHANISMS THAT LEAD TO PROGRESSIVE LIVER INJURY, INCLUDING THE METABOLIC ORIGINS OF NAFLD, THE EFFECT OF NAFLD ON HEPATIC GLUCOSE AND LIPID METABOLISM, BILE ACID TOXICITY, MACROPHAGE DYSFUNCTION, AND HEPATIC STELLATE CELL ACTIVATION, AND CONSIDER THE ROLE OF GENETIC, EPIGENETIC, AND ENVIRONMENTAL FACTORS THAT PROMOTE FIBROSIS PROGRESSION AND RISK OF HEPATOCELLULAR CARCINOMA IN NASH. 2021 5 3930 32 LIVER FIBROGENESIS: UN UPDATE ON ESTABLISHED AND EMERGING BASIC CONCEPTS. LIVER FIBROGENESIS IS DEFINED AS A DYNAMIC AND HIGHLY INTEGRATED PROCESS OCCURRING DURING CHRONIC INJURY TO LIVER PARENCHYMA THAT CAN RESULT IN EXCESS DEPOSITION OF EXTRACELLULAR MATRIX (ECM) COMPONENTS (I.E., LIVER FIBROSIS). LIVER FIBROGENESIS, TOGETHER WITH CHRONIC INFLAMMATORY RESPONSE, IS THEN PRIMARILY INVOLVED IN THE PROGRESSION OF CHRONIC LIVER DISEASES (CLD) IRRESPECTIVE OF THE SPECIFIC ETIOLOGY. IN THE PRESENT REVIEW WE WILL FIRST OFFER A SYNTHETIC AND UPDATED OVERVIEW OF MAJOR BASIC CONCEPTS IN RELATION TO THE ROLE OF MYOFIBROBLASTS (MFS), MACROPHAGES AND OTHER HEPATIC CELL POPULATIONS INVOLVED IN CLD TO THEN OFFER AN OVERVIEW OF ESTABLISHED AND EMERGING ISSUES AND MECHANISMS THAT HAVE BEEN PROPOSED TO FAVOR AND/OR PROMOTE CLD PROGRESSION. A SPECIAL FOCUS WILL BE DEDICATED TO SELECTED ISSUES THAT INCLUDE EMERGING FEATURES IN THE FIELD OF CHOLANGIOPATHIES, THE EMERGING ROLE OF GENETIC AND EPIGENETIC FACTORS AS WELL AS OF HYPOXIA, HYPOXIA-INDUCIBLE FACTORS (HIFS) AND RELATED MEDIATORS. 2020 6 2502 22 EPIGENETICS AND LIVER FIBROSIS. LIVER FIBROSIS ARISES BECAUSE PROLONGED INJURY COMBINED WITH EXCESSIVE SCAR DEPOSITION WITHIN HEPATIC PARENCHYMA ARISING FROM OVERACTIVE WOUND HEALING RESPONSE MEDIATED BY ACTIVATED MYOFIBROBLASTS. FIBROSIS IS THE COMMON END POINT FOR ANY TYPE OF CHRONIC LIVER INJURY INCLUDING ALCOHOLIC LIVER DISEASE, NONALCOHOLIC FATTY LIVER DISEASE, VIRAL HEPATITIS, AND CHOLESTATIC LIVER DISEASES. ALTHOUGH GENETIC INFLUENCES ARE IMPORTANT, IT IS EPIGENETIC MECHANISMS THAT HAVE BEEN SHOWN TO ORCHESTRATE MANY ASPECTS OF FIBROGENESIS IN THE LIVER. NEW DISCOVERIES IN THE FIELD ARE LEADING TOWARD THE DEVELOPMENT OF EPIGENETIC BIOMARKERS AND TARGETED THERAPIES. THIS REVIEW CONSIDERS EPIGENETIC MECHANISMS AS WELL AS RECENT ADVANCES IN EPIGENETIC PROGRAMMING IN THE CONTEXT OF HEPATIC FIBROSIS. 2017 7 4478 28 MOLECULAR PATHOGENESIS OF NONALCOHOLIC STEATOHEPATITIS- (NASH-) RELATED HEPATOCELLULAR CARCINOMA. THE PROPORTION OF OBESE OR DIABETIC POPULATION HAS BEEN ANTICIPATED TO INCREASE IN THE UPCOMING DECADES, WHICH RISES THE PREVALENCE OF NONALCOHOLIC FATTY LIVER DISEASE (NAFLD) AND ITS PROGRESSION TO NONALCOHOLIC STEATOHEPATITIS (NASH). RECENT EVIDENCE INDICATES THAT NASH IS THE MAIN CAUSE OF CHRONIC LIVER DISEASES AND IT IS AN IMPORTANT RISK FACTOR FOR DEVELOPMENT OF HEPATOCELLULAR CARCINOMA (HCC). ALTHOUGH THE LITERATURE ADDRESSING NASH-HCC IS GROWING RAPIDLY, LIMITED DATA IS AVAILABLE ABOUT THE ETIOLOGY OF NASH-RELATED HCC. EXPERIMENTAL STUDIES ON THE MOLECULAR MECHANISM OF HCC DEVELOPMENT IN NASH REVEAL THAT THE CARCINOGENESIS IS RELEVANT TO COMPLEX CHANGES IN SIGNALING PATHWAYS THAT MEDIATE CELL PROLIFERATION AND ENERGY METABOLISM. GENETIC OR EPIGENETIC MODIFICATIONS AND ALTERATIONS IN METABOLIC, IMMUNOLOGIC, AND ENDOCRINE PATHWAYS HAVE BEEN SHOWN TO BE CLOSELY RELATED TO INFLAMMATION, LIVER INJURY, AND FIBROSIS IN NASH ALONG WITH ITS SUBSEQUENT PROGRESSION TO HCC. IN THIS REVIEW, WE PROVIDE AN OVERVIEW ON THE CURRENT KNOWLEDGE OF NASH-RELATED HCC DEVELOPMENT AND EMPHASIZE MOLECULAR SIGNALING PATHWAYS REGARDING THEIR MECHANISM OF ACTION IN NASH-DERIVED HCC. 2018 8 3245 17 HEPATIC STELLATE CELLS AS KEY TARGET IN LIVER FIBROSIS. PROGRESSIVE LIVER FIBROSIS, INDUCED BY CHRONIC VIRAL AND METABOLIC DISORDERS, LEADS TO MORE THAN ONE MILLION DEATHS ANNUALLY VIA DEVELOPMENT OF CIRRHOSIS, ALTHOUGH NO ANTIFIBROTIC THERAPY HAS BEEN APPROVED TO DATE. TRANSDIFFERENTIATION (OR "ACTIVATION") OF HEPATIC STELLATE CELLS IS THE MAJOR CELLULAR SOURCE OF MATRIX PROTEIN-SECRETING MYOFIBROBLASTS, THE MAJOR DRIVER OF LIVER FIBROGENESIS. PARACRINE SIGNALS FROM INJURED EPITHELIAL CELLS, FIBROTIC TISSUE MICROENVIRONMENT, IMMUNE AND SYSTEMIC METABOLIC DYSREGULATION, ENTERIC DYSBIOSIS, AND HEPATITIS VIRAL PRODUCTS CAN DIRECTLY OR INDIRECTLY INDUCE STELLATE CELL ACTIVATION. DYSREGULATED INTRACELLULAR SIGNALING, EPIGENETIC CHANGES, AND CELLULAR STRESS RESPONSE REPRESENT CANDIDATE TARGETS TO DEACTIVATE STELLATE CELLS BY INDUCING REVERSION TO INACTIVATED STATE, CELLULAR SENESCENCE, APOPTOSIS, AND/OR CLEARANCE BY IMMUNE CELLS. CELL TYPE- AND TARGET-SPECIFIC PHARMACOLOGICAL INTERVENTION TO THERAPEUTICALLY INDUCE THE DEACTIVATION WILL ENABLE MORE EFFECTIVE AND LESS TOXIC PRECISION ANTIFIBROTIC THERAPIES. 2017 9 4464 25 MOLECULAR MECHANISMS OF NONALCOHOLIC FATTY LIVER DISEASE (NAFLD)/NONALCOHOLIC STEATOHEPATITIS (NASH). NONALCOHOLIC FATTY LIVER DISEASE (NAFLD) IS ONE OF THE MOST COMMON CHRONIC LIVER DISEASES WORLDWIDE AND HAS GARNERED INCREASING ATTENTION IN RECENT DECADES. NAFLD IS CHARACTERIZED BY A WIDE RANGE OF LIVER CHANGES, FROM SIMPLE STEATOSIS TO NONALCOHOLIC STEATOHEPATITIS (NASH), CIRRHOSIS, AND HEPATOCELLULAR CARCINOMA. THE PATHOGENESIS OF NAFLD/NASH IS VERY COMPLICATED AND INVOLVES LIPID ACCUMULATION, INSULIN RESISTANCE, INFLAMMATION, AND FIBROGENESIS. IN ADDITION, NAFLD IS CLOSELY ASSOCIATED WITH COMPLICATIONS SUCH AS OBESITY, DYSLIPIDEMIA, AND TYPE 2 DIABETES. IN PARTICULAR, THE CLINICAL SPECTRUM, PATHOPHYSIOLOGY, AND THERAPEUTIC OPTIONS OF NAFLD SHARE MANY THINGS IN COMMON WITH DIABETES. INSULIN RESISTANCE IS AN UNDERLYING BASIS FOR THE PATHOGENESIS OF DIABETES AND NAFLD. THIS CHAPTER FOCUSES ON THE MOLECULAR MECHANISM INVOLVED IN THE PATHOGENESIS OF INSULIN RESISTANCE, DIABETES, AND NASH/NAFLD INCLUDING THOSE THAT DRIVE DISEASE PROGRESSION SUCH AS OXIDATIVE STRESS, GENETIC AND EPIGENETIC MECHANISMS, ADIPONECTIN, CYTOKINES, AND IMMUNE CELLS. 2021 10 4326 25 MICRORNAS IN THE PATHOGENESIS OF NONALCOHOLIC FATTY LIVER DISEASE. NONALCOHOLIC FATTY LIVER DISEASE (NAFLD), OR, MORE ACCURATELY, METABOLIC ASSOCIATED FATTY LIVER DISEASE, ACCOUNTS FOR A LARGE PROPORTION OF CHRONIC LIVER DISORDERS WORLDWIDE AND IS CLOSELY ASSOCIATED WITH OTHER CONDITIONS SUCH AS CARDIOVASCULAR DISEASE, OBESITY, AND TYPE 2 DIABETES MELLITUS. NAFLD RANGES FROM SIMPLE STEATOSIS TO NONALCOHOLIC STEATOHEPATITIS (NASH) AND CAN PROGRESS TO CIRRHOSIS AND, EVENTUALLY, ALSO HEPATOCELLULAR CARCINOMA. THE MORBIDITY AND MORTALITY ASSOCIATED WITH NAFLD ARE INCREASING RAPIDLY YEAR ON YEAR. CONSEQUENTLY, THERE IS AN URGENT NEED TO UNDERSTAND THE ETIOLOGY AND PATHOGENESIS OF NAFLD AND IDENTIFY EFFECTIVE THERAPEUTIC TARGETS. MICRORNAS (MIRNAS), IMPORTANT EPIGENETIC FACTORS, HAVE RECENTLY BEEN PROPOSED TO PARTICIPATE IN NAFLD PATHOGENESIS. HERE, WE REVIEW THE ROLES OF MIRNAS IN LIPID METABOLISM, INFLAMMATION, APOPTOSIS, FIBROSIS, HEPATIC STELLATE CELL ACTIVATION, INSULIN RESISTANCE, AND OXIDATIVE STRESS, KEY FACTORS THAT CONTRIBUTE TO THE OCCURRENCE AND PROGRESSION OF NAFLD. ADDITIONALLY, WE SUMMARIZE THE ROLE OF MIRNA-ENRICHED EXTRACELLULAR VESICLES IN NAFLD. THESE MIRNAS MAY COMPRISE SUITABLE THERAPEUTIC TARGETS FOR THE TREATMENT OF THIS CONDITION. 2021 11 3270 21 HEPATOCELLULAR CARCINOMA IN THE CONTEXT OF NON-ALCOHOLIC STEATOHEPATITIS (NASH): RECENT ADVANCES IN THE PATHOGENIC MECHANISMS. HEPATOCELLULAR CARCINOMA (HCC) IS THE MOST COMMON TYPE OF LIVER CANCER. HCC IS PARTICULARLY AGGRESSIVE AND IS ONE OF THE LEADING CAUSES OF CANCER MORTALITY. IN RECENT DECADES, THE EPIDEMIOLOGICAL LANDSCAPE OF HCC HAS UNDERGONE SIGNIFICANT CHANGES. WHILE CHRONIC VIRAL HEPATITIS AND EXCESSIVE ALCOHOL CONSUMPTION HAVE LONG BEEN IDENTIFIED AS THE MAIN RISK FACTORS FOR HCC, NON-ALCOHOLIC STEATOHEPATITIS (NASH), PARALLELING THE WORLDWIDE EPIDEMIC OF OBESITY AND TYPE 2 DIABETES, HAS BECOME A GROWING CAUSE OF HCC IN THE US AND EUROPE. HERE, WE REVIEW THE RECENT ADVANCES IN EPIDEMIOLOGICAL, GENETIC, EPIGENETIC AND PATHOGENIC MECHANISMS AS WELL AS EXPERIMENTAL MOUSE MODELS THAT HAVE IMPROVED THE UNDERSTANDING OF NASH PROGRESSION TOWARD HCC. WE ALSO DISCUSS THE CLINICAL MANAGEMENT OF PATIENTS WITH NASH-RELATED HCC AND POSSIBLE THERAPEUTIC APPROACHES. 2020 12 2691 21 EVOLUTION OF HEPATIC FIBROSIS RESEARCH. MOLECULAR ANALYSIS OF HEPATIC FIBROGENESIS HAS PROGRESSED WITH RESPECT TO BOTH FIBROSIS PROGRESSION AND REGRESSION BY USING CELL BIOLOGICAL, MOLECULAR BIOLOGICAL AND (EPI)GENETIC APPROACHES. RECENT RESEARCHES HAVE REVEALED SOURCES OF COLLAGEN-PRODUCING CELLS OTHER THAN HEPATIC STELLATE CELLS IN THE LIVER, AND THE INVOLVEMENT OF THE INNATE IMMUNE SYSTEM AND OXIDATIVE STRESS IN THE FIBROTIC PROCESS HAS ATTRACTED NEW ATTENTION. TOGETHER WITH THESE ADVANCEMENTS IN BASIC KNOWLEDGE ON THE CELLULAR AND MOLECULAR BIOLOGY OF HEPATIC FIBROSIS, CLINICAL RESEARCHES HAVE LINKED THE CLARIFICATION OF THE RELATIONSHIP BETWEEN PROGRESSION OF THE FIBROSIS STAGE AND THERAPEUTIC EFFICACY FOR CHRONIC VIRAL HEPATITIS AND NON-ALCOHOLIC STEATOHEPATITIS AND VALIDATION OF THE REGRESSION OF ADVANCED FIBROSIS, EVEN CIRRHOSIS, OF APPROPRIATE THERAPIES USING MODERN MEDICINES. FURTHERMORE, NON-INVASIVE ASSESSMENT OF LIVER FIBROSIS USING AN ULTRASOUND-BASED MODALITY HAS BECOME A FOCUS IN THE CLINICAL DIAGNOSIS OF LIVER FIBROSIS INSTEAD OF LIVER BIOPSY. TAKEN TOGETHER, LIVER FIBROSIS RESEARCH HAS BEEN EVOLVING BOTH BASICALLY AND CLINICALLY IN THE PAST THREE DECADES. 2011 13 2322 23 EPIGENETIC REGULATION OF HEPATIC STELLATE CELL ACTIVATION AND LIVER FIBROSIS. CHRONIC LIVER INJURY TO HEPATOCYTES OR CHOLANGIOCYTES, WHEN LEFT UNMANAGED, LEADS TO THE DEVELOPMENT OF LIVER FIBROSIS, A CONDITION CHARACTERIZED BY THE EXCESSIVE INTRAHEPATIC DEPOSITION OF EXTRACELLULAR MATRIX PROTEINS. ACTIVATED HEPATIC STELLATE CELLS CONSTITUTE THE PREDOMINANT SOURCE OF EXTRACELLULAR MATRIX IN FIBROTIC LIVERS AND THEIR TRANSITION FROM A QUIESCENT STATE DURING FIBROGENESIS IS ASSOCIATED WITH IMPORTANT ALTERATIONS IN THEIR TRANSCRIPTIONAL AND EPIGENETIC LANDSCAPE. AREAS COVERED: WE BRIEFLY DESCRIBE THE PROCESSES INVOLVED IN HEPATIC STELLATE CELL ACTIVATION AND DISCUSS OUR CURRENT UNDERSTANDING OF ALTERATIONS IN THE EPIGENETIC LANDSCAPE, I.E DNA METHYLATION, HISTONE MODIFICATIONS AND THE FUNCTIONAL ROLE OF NON-CODING RNAS THAT ACCOMPANY THIS KEY EVENT IN THE DEVELOPMENT OF CHRONIC LIVER DISEASE. EXPERT COMMENTARY: ALTHOUGH GREAT PROGRESS HAS BEEN MADE, OUR UNDERSTANDING OF THE EPIGENETIC REGULATION OF HEPATIC STELLATE CELL ACTIVATION IS LIMITED AND, THUS FAR, INSUFFICIENT TO ALLOW THE DEVELOPMENT OF EPIGENETIC DRUGS THAT CAN SELECTIVELY INTERRUPT LIVER FIBROSIS. 2016 14 4104 19 MECHANISM AND THERAPEUTIC OPPORTUNITIES OF HISTONE MODIFICATIONS IN CHRONIC LIVER DISEASE. CHRONIC LIVER DISEASE (CLD) REPRESENTS A GLOBAL HEALTH PROBLEM, ACCOUNTING FOR THE HEAVY BURDEN OF DISABILITY AND INCREASED HEALTH CARE UTILIZATION. EPIGENOME ALTERATIONS PLAY AN IMPORTANT ROLE IN THE OCCURRENCE AND PROGRESSION OF CLD. HISTONE MODIFICATIONS, WHICH INCLUDE ACETYLATION, METHYLATION, AND PHOSPHORYLATION, REPRESENT AN ESSENTIAL PART OF EPIGENETIC MODIFICATIONS THAT AFFECT THE TRANSCRIPTIONAL ACTIVITY OF GENES. DIFFERENT FROM GENETIC MUTATIONS, HISTONE MODIFICATIONS ARE PLASTIC AND REVERSIBLE. THEY CAN BE MODULATED PHARMACOLOGICALLY WITHOUT CHANGING THE DNA SEQUENCE. THUS, THERE MIGHT BE CHANCES TO ESTABLISH INTERVENTIONAL SOLUTIONS BY TARGETING HISTONE MODIFICATIONS TO REVERSE CLD. HERE WE SUMMARIZED THE ROLES OF HISTONE MODIFICATIONS IN THE CONTEXT OF ALCOHOLIC LIVER DISEASE (ALD), METABOLIC ASSOCIATED FATTY LIVER DISEASE (MAFLD), VIRAL HEPATITIS, AUTOIMMUNE LIVER DISEASE, DRUG-INDUCED LIVER INJURY (DILI), AND LIVER FIBROSIS OR CIRRHOSIS. THE POTENTIAL TARGETS OF HISTONE MODIFICATIONS FOR TRANSLATION INTO THERAPEUTICS WERE ALSO INVESTIGATED. IN PROSPECT, HIGH EFFICACY AND LOW TOXICITY DRUGS THAT ARE SELECTIVELY TARGETING HISTONE MODIFICATIONS ARE REQUIRED TO COMPLETELY REVERSE CLD AND PREVENT THE DEVELOPMENT OF LIVER CIRRHOSIS AND MALIGNANCY. 2021 15 3931 16 LIVER INJURY AND THE ACTIVATION OF THE HEPATIC MYOFIBROBLASTS. LIVER FIBROSIS IS A WOUND HEALING PROCESS, THE END RESULT OF CHRONIC LIVER INJURY ELICITED BY DIFFERENT NOXIOUS STIMULI. ACTIVATED HEPATIC STELLATE CELLS OR MYOFIBROBLASTS AND PORTAL MYOFIBROBLASTS ARE CONSIDERED AS THE MAIN PRODUCERS OF THE EXTRACELLULAR MATRIX IN THE LIVER. UPON LIVER INJURY THE QUIESCENT STELLATE CELLS TRANSDIFFERENTIATE INTO MYOFIBROBLASTS A PROCESS HIGHLIGHTED BY THE LOSS OF VITAMIN A STORES, UPREGULATION OF INTERSTITIAL TYPE COLLAGENS, SMOOTH MUSCLE ALPHA ACTIN, MATRIX METALLOPROTEINASES, PROTEOGLYCANS, AND THE INDUCTION OF CELL SURVIVAL PATHWAYS. ACTIVATION OF HEPATIC STELLATE CELLS IS A RESULT OF A COMPLEX INTERPLAY BETWEEN THE PARENCHYMAL CELLS, IMMUNE CELLS, EXTRACELLULAR MATRIX MECHANICS AND EXTRAHEPATIC MILIEU SUCH AS THE GUT MICROBIOME. IN THIS REVIEW WE WILL FOCUS ON THE PATHOMECHANISM OF STELLATE CELL ACTIVATION FOLLOWING CHRONIC LIVER INJURY; WITH THE AIM OF IDENTIFYING POSSIBLE TREATMENT TARGETS FOR ANTI-FIBROGENIC AGENTS. 2013 16 2164 24 EPIGENETIC MECHANISMS IN HEPATIC STELLATE CELL ACTIVATION DURING LIVER FIBROSIS AND CARCINOGENESIS. LIVER FIBROSIS IS AN ESSENTIAL COMPONENT OF CHRONIC LIVER DISEASE (CLD) AND HEPATOCARCINOGENESIS. THE FIBROTIC STROMA IS A CONSEQUENCE OF SUSTAINED LIVER DAMAGE COMBINED WITH EXACERBATED EXTRACELLULAR MATRIX (ECM) ACCUMULATION. IN THIS CONTEXT, ACTIVATION OF HEPATIC STELLATE CELLS (HSCS) PLAYS A KEY ROLE IN BOTH INITIATION AND PERPETUATION OF FIBROGENESIS. THESE CELLS SUFFER PROFOUND REMODELING OF GENE EXPRESSION IN THIS PROCESS. THIS REVIEW IS FOCUSED ON THE EPIGENETIC ALTERATIONS PARTICIPATING IN THE TRANSDIFFERENTIATION OF HSCS FROM THE QUIESCENT TO ACTIVATED STATE. RECENT ADVANCES IN THE FIELD OF DNA METHYLATION AND POST-TRANSLATIONAL MODIFICATIONS (PTM) OF HISTONES (ACETYLATION AND METHYLATION) PATTERNS ARE DISCUSSED HERE, TOGETHER WITH ALTERED EXPRESSION AND ACTIVITY OF EPIGENETIC REMODELERS. WE ALSO CONSIDER RECENT ADVANCES IN TRANSLATIONAL APPROACHES, INCLUDING THE USE OF EPIGENETIC MARKS AS BIOMARKERS AND THE PROMISING ANTIFIBROTIC PROPERTIES OF EPIGENETIC DRUGS THAT ARE CURRENTLY BEING USED IN PATIENTS. 2019 17 1348 24 DETERMINANTS OF FIBROSIS PROGRESSION AND REGRESSION IN NASH. CIRRHOSIS HAS BECOME THE MAJOR LIVER-RELATED CLINICAL ENDPOINT IN NON-ALCOHOLIC STEATOHEPATITIS (NASH). HOWEVER, PROGRESSION TO CIRRHOSIS IS LESS PREDICTABLE IN NASH THAN IN OTHER CHRONIC LIVER DISEASES. THIS IS DUE TO THE COMPLEX AND MULTIFACTORIAL AETIOLOGY OF NASH, WHICH IS DETERMINED BY LIFESTYLE AND NUTRITION, MULTIPLE GENETIC AND EPIGENETIC FACTORS, AND A PROMINENT ROLE OF HEPATIC AND EXTRAHEPATIC COMORBIDITIES. THUS, MODEST CHANGES IN THESE COFACTORS CAN ALSO INDUCE FIBROSIS REGRESSION, AT LEAST IN PATIENTS WITH PRECIRRHOTIC LIVER DISEASE. FIBROGENESIS IN NASH CORRELATES WITH, BUT IS INDIRECTLY COUPLED TO, CLASSICAL INFLAMMATION, SINCE FIBROSIS PROGRESSION IS DRIVEN BY REPETITIVE PERIODS OF REPAIR. WHILE HEPATOCYTE LIPOAPOPTOSIS IS A KEY DRIVING FORCE OF FIBROSIS PROGRESSION, ACTIVATED HEPATIC STELLATE CELLS, MYOFIBROBLASTS, CHOLANGIOCYTES, MACROPHAGES AND COMPONENTS OF THE PATHOLOGICAL EXTRACELLULAR MATRIX ARE MAJOR FIBROGENIC EFFECTORS AND THUS PHARMACOLOGICAL TARGETS FOR THERAPIES AIMED AT INHIBITION OF FIBROSIS PROGRESSION OR INDUCTION OF FIBROSIS REVERSAL. THE ADVENT OF NOVEL, HIGHLY SENSITIVE AND SPECIFIC SERUM BIOMARKERS AND IMAGING METHODS TO ASSESS THE DYNAMICS OF LIVER FIBROSIS IN NASH WILL IMPROVE DETECTION, STRATIFICATION AND FOLLOW-UP OF PATIENTS WITH PROGRESSIVE NASH . THESE NON-INVASIVE TOOLS WILL ALSO PROMOTE THE CLINICAL DEVELOPMENT OF ANTIFIBROTIC DRUGS, BY PERMITTING THE DESIGN OF LEAN PROOF-OF-CONCEPT STUDIES, AND ENABLING DEVELOPMENT OF A PERSONALISED ANTIFIBROTIC THERAPY FOR PATIENTS WITH RAPID FIBROSIS PROGRESSION OR ADVANCED DISEASE. 2018 18 4720 23 NONCODING RNAS AS ADDITIONAL MEDIATORS OF EPIGENETIC REGULATION IN NONALCOHOLIC FATTY LIVER DISEASE. NONALCOHOLIC FATTY LIVER DISEASE (NAFLD) HAS EMERGED AS THE MOST COMMON CAUSE OF CHRONIC LIVER DISORDER WORLDWIDE. IT REPRESENTS A SPECTRUM THAT INCLUDES A CONTINUUM OF DIFFERENT CLINICAL ENTITIES RANGING FROM SIMPLE STEATOSIS TO NONALCOHOLIC STEATOHEPATITIS, WHICH CAN EVOLVE TO CIRRHOSIS AND IN SOME CASES TO HEPATOCELLULAR CARCINOMA, ULTIMATELY LEADING TO LIVER FAILURE. THE PATHOGENESIS OF NAFLD AND THE MECHANISMS UNDERLYING ITS PROGRESSION TO MORE PATHOLOGICAL STAGES ARE NOT COMPLETELY UNDERSTOOD. BESIDES GENETIC FACTORS, EVIDENCE INDICATES THAT EPIGENETIC MECHANISMS OCCURRING IN RESPONSE TO ENVIRONMENTAL STIMULI ALSO CONTRIBUTE TO THE DISEASE RISK. NONCODING RNAS (NCRNAS), INCLUDING MICRORNAS, LONG NONCODING RNAS, AND CIRCULAR RNAS, ARE ONE OF THE EPIGENETIC FACTORS THAT PLAY KEY REGULATORY ROLES IN THE DEVELOPMENT OF NAFLD. AS THE FIELD OF NCRNAS IS RAPIDLY EVOLVING, THE PRESENT REVIEW AIMS TO EXPLORE THE CURRENT STATE OF KNOWLEDGE ON THE ROLES OF THESE RNA SPECIES IN THE PATHOGENESIS OF NAFLD, HIGHLIGHT RELEVANT MECHANISMS BY WHICH SOME NCRNAS CAN MODULATE REGULATORY NETWORKS IMPLICATED IN NAFLD, AND DISCUSS KEY CHALLENGES AND FUTURE DIRECTIONS FACING CURRENT RESEARCH IN THE HOPES OF DEVELOPING NCRNAS AS NEXT-GENERATION NON-INVASIVE DIAGNOSTICS AND THERAPIES IN NAFLD AND SUBSEQUENT PROGRESSION TO HEPATOCELLULAR CARCINOMA. 2022 19 2817 22 FIBROSIS IN THE LIVER: ACUTE PROTECTION AND CHRONIC DISEASE. THE UNDERSTANDING OF THE CELLULAR AND MOLECULAR MECHANISMS OF THE FIBROTIC WOUND-HEALING RESPONSE OF THE LIVER HAS MADE DRAMATIC PROGRESS IN THE PAST 20 YEARS. HEPATIC STELLATE CELLS (HSCS), WHICH AFTER LIVER INJURY PROLIFERATE AND TRANSDIFFERENTIATE TO MYOFIBROBLASTS, HAVE EMERGED AS THE PRIMARY SOURCE OF THE FIBROTIC RESPONSE, EVEN THOUGH OTHER FIBROGENIC CELLS MAY ALSO CONTRIBUTE TO THE PRODUCTION OF EXTRACELLULAR MATRIX (ECM). ADVANCES IN THE UNDERSTANDING OF HSC REGULATION INCLUDE APOPTOTIC SIGNALING, ANGIOGENIC SIGNALING, AND RESPONSES TO OXIDATIVE STRESS. THE ECM HAS EMERGED NOT ONLY AS A STRUCTURAL SCAFFOLD, BUT ALSO AS A DYNAMIC AND INTERACTIVE MATRIX REGULATING STELLATE CELL ACTIVATION. ADDITIONALLY, THE INNATE IMMUNE SYSTEM AND IMMUNE SIGNALING, AS WELL AS A BROADENING UNDERSTANDING OF THE TRANSCRIPTIONAL REGULATION INCLUDING MICRORNAS AND EPIGENETIC EVENTS OFFER POTENTIAL THERAPEUTIC TARGETS. UNRAVELING GENETIC DETERMINANTS RELATED TO MECHANISMS OF HEPATIC FIBROGENESIS PROMISE INDIVIDUALIZED THERAPY OR PREVENTION. HEPATIC FIBROSIS AND CIRRHOSIS HAVE EMERGED AS TREATABLE AND POTENTIALLY REVERSIBLE CONSEQUENCE OF CHRONIC LIVER DISEASE. 2010 20 5807 26 STRATEGIES, MODELS AND BIOMARKERS IN EXPERIMENTAL NON-ALCOHOLIC FATTY LIVER DISEASE RESEARCH. NON-ALCOHOLIC FATTY LIVER DISEASE ENCOMPASSES A SPECTRUM OF LIVER DISEASES, INCLUDING SIMPLE STEATOSIS, STEATOHEPATITIS, LIVER FIBROSIS AND CIRRHOSIS AND HEPATOCELLULAR CARCINOMA. NON-ALCOHOLIC FATTY LIVER DISEASE IS CURRENTLY THE MOST DOMINANT CHRONIC LIVER DISEASE IN WESTERN COUNTRIES DUE TO THE FACT THAT HEPATIC STEATOSIS IS ASSOCIATED WITH INSULIN RESISTANCE, TYPE 2 DIABETES MELLITUS, OBESITY, METABOLIC SYNDROME AND DRUG-INDUCED INJURY. A VARIETY OF CHEMICALS, MAINLY DRUGS, AND DIETS IS KNOWN TO CAUSE HEPATIC STEATOSIS IN HUMANS AND RODENTS. EXPERIMENTAL NON-ALCOHOLIC FATTY LIVER DISEASE MODELS RELY ON THE APPLICATION OF A DIET OR THE ADMINISTRATION OF DRUGS TO LABORATORY ANIMALS OR THE EXPOSURE OF HEPATIC CELL LINES TO THESE DRUGS. MORE RECENTLY, GENETICALLY MODIFIED RODENTS OR ZEBRAFISH HAVE BEEN INTRODUCED AS NON-ALCOHOLIC FATTY LIVER DISEASE MODELS. CONSIDERABLE INTEREST NOW LIES IN THE DISCOVERY AND DEVELOPMENT OF NOVEL NON-INVASIVE BIOMARKERS OF NON-ALCOHOLIC FATTY LIVER DISEASE, WITH SPECIFIC FOCUS ON HEPATIC STEATOSIS. EXPERIMENTAL DIAGNOSTIC BIOMARKERS OF NON-ALCOHOLIC FATTY LIVER DISEASE, SUCH AS (EPI)GENETIC PARAMETERS AND '-OMICS'-BASED READ-OUTS ARE STILL IN THEIR INFANCY, BUT SHOW GREAT PROMISE. IN THIS PAPER, THE ARRAY OF TOOLS AND MODELS FOR THE STUDY OF LIVER STEATOSIS IS DISCUSSED. FURTHERMORE, THE CURRENT STATE-OF-ART REGARDING EXPERIMENTAL BIOMARKERS SUCH AS EPIGENETIC, GENETIC, TRANSCRIPTOMIC, PROTEOMIC AND METABONOMIC BIOMARKERS WILL BE REVIEWED. 2015