1 3930 97 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 2 5805 38 STRATEGIES TO PREVENT AND REVERSE LIVER FIBROSIS IN HUMANS AND LABORATORY ANIMALS. LIVER FIBROSIS RESULTS FROM CHRONIC DAMAGE TO THE LIVER IN CONJUNCTION WITH VARIOUS PATHWAYS AND IS MEDIATED BY A COMPLEX MICROENVIRONMENT. BASED ON CLINICAL OBSERVATIONS, IT IS NOW EVIDENT THAT FIBROSIS IS A DYNAMIC, BIDIRECTIONAL PROCESS WITH AN INHERENT CAPACITY FOR RECOVERY AND REMODELING. THE MAJOR MECHANISMS INVOLVED IN LIVER FIBROSIS INCLUDE THE REPETITIVE INJURY OF HEPATOCYTES, THE ACTIVATION OF THE INFLAMMATORY RESPONSE AFTER INJURY STIMULATION, AND THE ACTIVATION AND PROLIFERATION OF HEPATIC STELLATE CELLS (HSCS), WHICH REPRESENTS THE MAJOR EXTRACELLULAR MATRIX (ECM)-PRODUCING CELLS, STIMULATED BY HEPATOCYTE INJURY AND INFLAMMATION. THE MICROENVIRONMENT IN THE LIVER IS SYNERGISTICALLY REGULATED ABNORMAL ECM DEPOSITION, SCAR FORMATION, ANGIOGENESIS, AND FIBROGENESIS. MOREOVER, RECENT STUDIES HAVE CLARIFIED NOVEL MECHANISM IN FIBROSIS SUCH AS EPIGENETIC REGULATION OF HSCS, THE LEPTIN AND PPARGAMMA PATHWAYS, THE COAGULATION SYSTEM, AND EVEN AUTOPHAGY. UNCOVERING THE MECHANISMS OF LIVER FIBROGENESIS PROVIDES A BASIS TO DEVELOP POTENTIAL THERAPIES TO REVERSE AND TREAT THE FIBROTIC RESPONSE, THEREBY IMPROVING THE OUTCOMES OF PATIENTS WITH CHRONIC LIVER DISEASE. ALTHOUGH BOTH SCIENTIFIC AND CLINICAL CHALLENGES REMAIN, EMERGING STUDIES ATTEMPT TO REVEAL THE IDEAL ANTI-FIBROTIC DRUG THAT COULD BE EASILY DELIVERED TO THE LIVER WITH HIGH SPECIFICITY AND LOW TOXICITY. THIS REVIEW HIGHLIGHTS THE MECHANISMS, INCLUDING NOVEL PATHWAYS UNDERLYING FIBROGENESIS THAT MAY BE TRANSLATED INTO PREVENTIVE AND TREATMENT STRATEGIES, REVIEWS BOTH CURRENT AND NOVEL AGENTS THAT TARGET SPECIFIC PATHWAYS OR MULTIPLE TARGETS, AND DISCUSSES NOVEL DRUG DELIVERY SYSTEMS SUCH AS NANOTECHNOLOGY THAT CAN BE APPLIED IN THE TREATMENT OF LIVER FIBROSIS. IN ADDITION, WE ALSO DISCUSS SOME CURRENT TREATMENT STRATEGIES THAT ARE BEING APPLIED IN ANIMAL MODELS AND IN CLINICAL TRIALS. 2015 3 2502 28 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 4 4613 32 NEOVASCULARIZATION IS A KEY FEATURE OF LIVER FIBROSIS PROGRESSION: ANTI-ANGIOGENESIS AS AN INNOVATIVE WAY OF LIVER FIBROSIS TREATMENT. LIVER FIBROSIS AFFECTS OVER 100 MILLION PEOPLE IN THE WORLD; IT REPRESENTS A MULTIFACTORIAL, FIBRO-INFLAMMATORY DISORDER CHARACTERIZED BY EXACERBATED PRODUCTION OF EXTRACELLULAR MATRIX WITH CONSEQUENT ABERRATION OF HEPATIC TISSUE. THE AETIOLOGY OF THIS DISEASE IS VERY COMPLEX AND SEEMS TO INVOLVE A BROAD SPECTRUM OF FACTORS INCLUDING THE LIFESTYLE, ENVIRONMENT FACTORS, GENES AND EPIGENETIC CHANGES. MORE EVIDENCES INDICATE THAT ANGIOGENESIS, A PROCESS CONSISTING IN THE FORMATION OF NEW BLOOD VESSELS FROM PRE-EXISTING VESSELS, PLAYS A CRUCIAL ROLE IN THE PROGRESSION OF LIVER FIBROSIS. CENTRAL TO THE PATHOGENESIS OF LIVER FIBROSIS IS THE HEPATIC STELLATE CELLS (HSCS) WHICH REPRESENT A CROSSROAD AMONG INFLAMMATION, FIBROSIS AND ANGIOGENESIS. QUIESCENT HSCS CAN BE STIMULATED BY A HOST OF GROWTH FACTORS, PRO-INFLAMMATORY MEDIATORS PRODUCED BY DAMAGED RESIDENT LIVER CELL TYPES, AS WELL AS BY HYPOXIA, CONTRIBUTING TO NEOANGIOGENESIS, WHICH IN TURN CAN BE A BRIDGE BETWEEN ACUTE AND CHRONIC INFLAMMATION. AS MATTER OF FACT, STUDIES DEMONSTRATED THAT NEUTRALIZATION OF VASCULAR ENDOTHELIAL GROWTH FACTOR AS WELL AS OTHER PROANGIOGENIC AGENTS CAN ATTENUATE THE PROGRESSION OF LIVER FIBROSIS. WITH THIS REVIEW, OUR INTENT IS TO DISCUSS THE CAUSE AND THE ROLE OF ANGIOGENESIS IN LIVER FIBROSIS FOCUSING ON THE CURRENT KNOWLEDGE ABOUT THE IMPACT OF ANTI-ANGIOGENETIC THERAPIES IN THIS PATHOLOGY. 2020 5 6913 25 [VARIOUS PATHWAYS LEADING TO THE PROGRESSION OF CHRONIC LIVER DISEASES]. AS THE RESULT OF VARIOUS EFFECTS (VIRUSES, METABOLIC DISEASES, NUTRITIONAL FACTORS, TOXIC AGENTS, AUTOIMMUNE PROCESSES) ABNORMAL LIVER FUNCTION, LIVER STEATOSIS AND CONNECTIVE TISSUE REMODELING MAY DEVELOP. PROGRESSION OF THIS PROCESS IS COMPLEX INCLUDING VARIOUS PATHWAYS AND A NUMBER OF FACTORS. THE AUTHORS SUMMARIZE THE FACTORS INVOLVED IN THE PROGRESSION OF CHRONIC LIVER DISEASE. THEY DESCRIBE THE ROLE OF CELLS AND THE PRODUCED INFLAMMATORY MEDIATORS AND CYTOKINES, AS WELL AS THE RELATIONSHIP BETWEEN THE DISEASE AND THE INTESTINAL FLORA. THEY EMPHASIZE THE ROLE OF OXIDATIVE STRESS, MITOCHONDRIAL DYSFUNCTION AND CELL DEATH IN DISEASE PROGRESSION. INSULIN RESISTANCE AND MICRO-ELEMENTS (IRON, COPPER) IN RELATION TO LIVER DAMAGE ARE ALSO DISCUSSED, AND GENETIC AND EPIGENETIC ASPECTS UNDERLYING DISEASE PROGRESSION ARE SUMMARIZED. DISCOVERY OF NOVEL TREATMENT OPTIONS, ASSESSMENT OF THE EFFECTIVENESS OF TREATMENT, AS WELL AS THE SUCCESS AND PROPER TIMING OF LIVER TRANSPLANTATION MAY DEPEND ON A BETTER UNDERSTANDING OF THE PROCESS OF DISEASE PROGRESSION. 2016 6 2817 30 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 7 2164 32 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 8 2933 34 GENESIS OF THE MYOFIBROBLAST IN LUNG INJURY AND FIBROSIS. TISSUE INJURY INCITES A REPAIR RESPONSE WITH A KEY MESENCHYMAL COMPONENT THAT PROVIDES THE ESSENTIAL CONNECTIVE TISSUE FOR SUBSEQUENT REGENERATION OR PATHOLOGICAL FIBROSIS. THE FIBROBLAST IS THE MAJOR MESENCHYMAL CELL TYPE TO BE IMPLICATED IN THIS CONNECTIVE TISSUE RESPONSE, AND IT IS IN ITS ACTIVATED OR DIFFERENTIATED FORM THAT IT PARTICIPATES IN THE REPAIR PROCESS. THE MYOFIBROBLAST REPRESENTS SUCH AN ACTIVATED MESENCHYMAL CELL AND IS A KEY SOURCE OF EXTRACELLULAR MATRIX AND INFLAMMATORY/FIBROGENIC CYTOKINES AS WELL AS PARTICIPATING IN WOUND CONTRACTION. ALTHOUGH SUCCESSFUL HEALING RESULTS IN GRADUAL DISAPPEARANCE OF MYOFIBROBLASTS, THEIR PERSISTENCE IS ASSOCIATED WITH CHRONIC AND PROGRESSIVE FIBROSIS. THUS, ELUCIDATION OF THE MECHANISM INVOLVED IN THE GENESIS OF THE MYOFIBROBLAST SHOULD PROVIDE INSIGHT INTO BOTH PATHOGENESIS OF CHRONIC FIBROTIC DISEASES AND THERAPEUTIC STRATEGIES FOR THEIR MANAGEMENT AND CONTROL. ALTHOUGH THE FIBROBLAST IS A WELL-DOCUMENTED PROGENITOR CELL FOR THE MYOFIBROBLAST, RECENT STUDIES HAVE SUGGESTED ADDITIONAL PRECURSOR CELLS THAT HAVE THE POTENTIAL TO GIVE RISE TO THE MYOFIBROBLAST. MANY OF THE STUDIES FOCUSED ON MECHANISMS AND FACTORS THAT REGULATE INDUCTION OF ALPHA-SMOOTH MUSCLE ACTIN EXPRESSION, A KEY AND COMMONLY USED MARKER OF THE MYOFIBROBLAST. THESE REVEAL COMPLEX AND MULTIFACTORIAL MECHANISMS INVOLVING TRANSCRIPTIONAL AND EPIGENETIC REGULATION AND IMPLICATING DIVERSE CELL-SIGNALING PATHWAYS, INCLUDING THOSE ACTIVATED BY THE POTENT FIBROGENIC CYTOKINE TRANSFORMING GROWTH FACTOR BETA. DESPITE THESE EXTENSIVE STUDIES, MANY ASPECTS REMAIN POORLY UNDERSTOOD, WITH THE SUGGESTION THAT ADDITIONAL NOVEL MECHANISMS REMAIN TO BE DISCOVERED. FUTURE STUDIES WITH THE HELP OF NEWLY DEVELOPED TECHNICAL ADVANCEMENTS SHOULD EXPEDITE DISCOVERY IN THIS DIRECTION. 2012 9 2283 27 EPIGENETIC REGULATION IN FIBROSIS PROGRESS. FIBROSIS, A COMMON PROCESS OF CHRONIC INFLAMMATORY DISEASES, IS DEFINED AS A REPAIR RESPONSE DISORDER WHEN ORGANS UNDERGO CONTINUOUS DAMAGE, ULTIMATELY LEADING TO SCAR FORMATION AND FUNCTIONAL FAILURE. AROUND THE WORLD, FIBROTIC DISEASES CAUSE HIGH MORTALITY, UNFORTUNATELY, WITH LIMITED TREATMENT MEANS IN CLINICAL PRACTICE. WITH THE DEVELOPMENT AND APPLICATION OF DEEP SEQUENCING TECHNOLOGY, COMPREHENSIVELY EXPLORING THE EPIGENETIC MECHANISM IN FIBROSIS HAS BEEN ALLOWED. EXTENSIVE REMODELING OF EPIGENETICS CONTROLLING VARIOUS CELLS PHENOTYPE AND MOLECULAR MECHANISMS INVOLVED IN FIBROGENESIS WAS SUBSEQUENTLY VERIFIED. IN THIS REVIEW, WE SUMMARIZE THE REGULATORY MECHANISMS OF DNA METHYLATION, HISTONE MODIFICATION, NONCODING RNAS (NCRNAS) AND N6-METHYLADENOSINE (M6A) MODIFICATION IN ORGAN FIBROSIS, FOCUSING ON HEART, LIVER, LUNG AND KIDNEY. ADDITIONALLY, WE EMPHASIZE THE DIVERSITY OF EPIGENETICS IN THE CELLULAR AND MOLECULAR MECHANISMS RELATED TO FIBROSIS. FINALLY, THE POTENTIAL AND PROSPECT OF TARGETED THERAPY FOR FIBROSIS BASED ON EPIGENETIC IS DISCUSSED. 2021 10 2691 25 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 11 4980 41 PATHOPHYSIOLOGY OF LIVER FIBROSIS. PROGRESSIVE ACCUMULATION OF FIBRILLAR EXTRACELLULAR MATRIX (ECM) IN THE LIVER IS THE CONSEQUENCE OF REITERATED LIVER TISSUE DAMAGE DUE TO INFECTIVE (MOSTLY HEPATITIS B AND C VIRUSES), TOXIC/DRUG-INDUCED, METABOLIC AND AUTOIMMUNE CAUSES, AND THE RELATIVE CHRONIC ACTIVATION OF THE WOUND-HEALING REACTION. THE PROCESS MAY RESULT IN CLINICALLY EVIDENT LIVER CIRRHOSIS AND HEPATIC FAILURE. ALTHOUGH CIRRHOSIS IS THE COMMON RESULT OF PROGRESSIVE FIBROGENESIS, THERE ARE DISTINCT PATTERNS OF FIBROTIC DEVELOPMENT RELATED TO THE UNDERLYING DISORDERS CAUSING THE FIBROSIS. THESE DIFFERENT PATTERNS OF FIBROGENIC EVOLUTION ARE RELATED TO DIFFERENT FACTORS AND PARTICULARLY: (1) THE TOPOGRAPHIC LOCALIZATION OF TISSUE DAMAGE, (2) THE RELATIVE CONCENTRATION OF PROFIBROGENIC FACTORS AND (3) THE PREVALENT PROFIBROGENIC MECHANISM(S). THE MECHANISMS RESPONSIBLE FOR THE FIBROGENIC EVOLUTION OF CHRONIC LIVER DISEASES CAN BE SUMMARIZED IN THREE MAIN GROUPS: CHRONIC ACTIVATION OF THE WOUND-HEALING REACTION, OXIDATIVE STRESS-RELATED MOLECULAR MECHANISMS, AND THE DERANGEMENT OF THE SO-CALLED 'EPITHELIAL-MESENCHYMAL' INTERACTION LEADING TO THE GENERATION OF REACTIVE CHOLANGIOCYTES AND PERIBILIARY FIBROSIS. MOST OF THE KNOWLEDGE ON THE CELL AND MOLECULAR BIOLOGY OF HEPATIC FIBROSIS DERIVES FROM IN VITRO STUDIES EMPLOYING CULTURE OF ACTIVATED HEPATIC STELLATE CELLS ISOLATED FROM RAT, MOUSE OR HUMAN LIVER. IT IS NOW EVIDENT THAT OTHER ECM-PRODUCING CELLS, I.E. FIBROBLASTS AND MYOFIBROBLASTS OF THE PORTAL TRACT AND CIRCULATING 'FIBROCYTES', ARE LIKELY TO CONTRIBUTE TO LIVER FIBROSIS. MORE RECENTLY, THE ATTENTION IS PROGRESSIVELY SHIFTING TO THE PROFIBROTIC MICROENVIRONMENT OF THE LIVER WITH INCREASING INTEREST FOR THE ROLE OF IMMUNE CELLS AND SPECIFIC SUBSETS OF MACROPHAGES REGULATING THE PROGRESSION OR THE REGRESSION OF FIBROSIS, THE ROLE OF INTESTINAL MICROBIOTA AND THE INFLUENCE OF TISSUE STIFFNESS. OTHER MAJOR AREAS OF DEVELOPMENT INCLUDE THE ROLE OF TISSUE HYPOXIA AND THE ESTABLISHMENT OF AN ANAEROBIC PROINFLAMMATORY ENVIRONMENT AND THE INFLUENCE OF EPIGENETIC MODIFICATION IN CONDITIONING THE PROGRESSION OF FIBROSIS. 2015 12 2323 26 EPIGENETIC REGULATION OF HEPATIC STELLATE CELL ACTIVATION AND MACROPHAGE IN CHRONIC LIVER INFLAMMATION. CHRONIC LIVER INFLAMMATION IS A COMPLEX PATHOLOGICAL PROCESS UNDER DIFFERENT STRESS CONDITIONS, AND THE ROLES OF STELLATE CELLS AND MACROPHAGES IN CHRONIC LIVER INFLAMMATION HAVE BEEN WIDELY REPORTED. MODERATE LIVER INFLAMMATION CAN PROTECT THE LIVER FROM DAMAGE AND FACILITATE THE RECOVERY OF LIVER INJURY. HOWEVER, AN INFLAMMATORY RESPONSE THAT IS TOO INTENSE CAN RESULT IN MASSIVE DEATH OF HEPATOCYTES, WHICH LEADS TO IRREVERSIBLE DAMAGE TO THE LIVER PARENCHYMA. EPIGENETIC REGULATION PLAYS A KEY PART IN LIVER INFLAMMATION. THIS STUDY REVIEWS THE REGULATION OF EPIGENETICS ON STELLATE CELLS AND MACROPHAGES TO EXPLORE THE NEW MECHANISMS OF EPIGENETICS ON LIVER INFLAMMATION AND PROVIDE NEW IDEAS FOR THE TREATMENT OF LIVER DISEASE. 2021 13 4043 25 MACROPHAGES IN CHRONIC LIVER FAILURE: DIVERSITY, PLASTICITY AND THERAPEUTIC TARGETING. CHRONIC LIVER INJURY RESULTS IN IMMUNE-DRIVEN PROGRESSIVE FIBROSIS, WITH RISK OF CIRRHOSIS DEVELOPMENT AND IMPACT ON MORBIDITY AND MORTALITY. PERSISTENT LIVER CELL DAMAGE AND DEATH CAUSES IMMUNE CELL ACTIVATION AND INFLAMMATION. PATIENTS WITH ADVANCED CIRRHOSIS ADDITIONALLY EXPERIENCE PATHOLOGICAL BACTERIAL TRANSLOCATION, EXPOSURE TO MICROBIAL PRODUCTS AND CHRONIC ENGAGEMENT OF THE IMMUNE SYSTEM. BACTERIAL INFECTIONS HAVE A HIGH INCIDENCE IN CIRRHOSIS, WITH SPONTANEOUS BACTERIAL PERITONITIS BEING THE MOST COMMON, WHILE THE SUBSEQUENT SYSTEMIC INFLAMMATION, ORGAN FAILURE AND IMMUNE DYSREGULATION INCREASE THE MORTALITY RISK. TISSUE-RESIDENT AND RECRUITED MACROPHAGES PLAY A CENTRAL PART IN THE DEVELOPMENT OF INFLAMMATION AND FIBROSIS PROGRESSION. IN THE LIVER, ADIPOSE TISSUE, PERITONEUM AND INTESTINES, DIVERSE MACROPHAGE POPULATIONS EXHIBIT GREAT PHENOTYPIC AND FUNCTIONAL PLASTICITY DETERMINED BY THEIR ONTOGENY, EPIGENETIC PROGRAMMING AND LOCAL MICROENVIRONMENT. THESE CHANGES CAN, AT DIFFERENT TIMES, PROMOTE OR AMELIORATE DISEASE STATES AND THEREFORE REPRESENT POTENTIAL TARGETS FOR MACROPHAGE-DIRECTED THERAPIES. IN THIS REVIEW, WE DISCUSS THE EVIDENCE FOR MACROPHAGE PHENOTYPIC AND FUNCTIONAL ALTERATIONS IN TISSUE COMPARTMENTS DURING THE DEVELOPMENT AND PROGRESSION OF CHRONIC LIVER FAILURE IN DIFFERENT AETIOLOGIES AND HIGHLIGHT THE POTENTIAL OF MACROPHAGE MODULATION AS A THERAPEUTIC STRATEGY FOR LIVER DISEASE. 2021 14 2180 29 EPIGENETIC MECHANISMS OF PANCREATOBILIARY FIBROSIS. PURPOSE OF REVIEW: THE GOAL OF THIS MANUSCRIPT IS TO REVIEW THE CURRENT LITERATURE RELATED TO FIBROGENESIS IN THE PANCREATOBILIARY SYSTEM AND HOW THIS PROCESS CONTRIBUTES TO PANCREATIC AND BILIARY DISEASES. IN PARTICULAR, WE SEEK TO DEFINE THE CURRENT STATE OF KNOWLEDGE REGARDING THE EPIGENETIC MECHANISMS THAT GOVERN AND REGULATE TISSUE FIBROSIS IN THESE ORGANS. A BETTER UNDERSTANDING OF THESE UNDERLYING MOLECULAR EVENTS WILL SET THE STAGE FOR FUTURE EPIGENETIC THERAPEUTICS. RECENT FINDINGS: WE HIGHLIGHT THE SIGNIFICANT ADVANCES THAT HAVE BEEN MADE IN DEFINING THE PATHOGENESIS OF PANCREATOBILIARY FIBROSIS AS IT RELATES TO CHRONIC PANCREATITIS, PANCREATIC CANCER, AND THE FIBRO-OBLITERATIVE CHOLANGIOPATHIES. WE ALSO REVIEW THE CELL TYPES INVOLVED AS WELL AS CONCEPTS RELATED TO EPITHELIAL-MESENCHYMAL CROSSTALK. FURTHERMORE, WE OUTLINE IMPORTANT SIGNALING PATHWAYS (E.G., TGFBETA) AND DIVERSE EPIGENETIC PROCESSES (I.E., DNA METHYLATION, NON-CODING RNAS, HISTONE MODIFICATIONS, AND 3D CHROMATIN REMODELING) THAT REGULATE FIBROGENIC GENE NETWORKS IN THESE CONDITIONS. WE REVIEW A GROWING BODY OF SCIENTIFIC EVIDENCE LINKING EPIGENETIC REGULATORY EVENTS TO FIBROTIC DISEASE STATES IN THE PANCREAS AND BILIARY SYSTEM. ADVANCES IN THIS UNDERSTUDIED AREA WILL BE CRITICAL TOWARD DEVELOPING EPIGENETIC PHARMACOLOGICAL APPROACHES THAT MAY LEAD TO MORE EFFECTIVE TREATMENTS FOR THESE DEVASTATING AND DIFFICULT TO TREAT DISORDERS. 2019 15 2381 25 EPIGENETIC REGULATION OF WOUND HEALING AND FIBROSIS. PURPOSE OF REVIEW: WOUND HEALING IS A NORMAL PHYSIOLOGICAL RESPONSE TO TISSUE INJURY WHICH CAN OCCUR IN ANY ORGAN. MECHANISMS THAT ORCHESTRATE WOUND HEALING IN DIFFERENT ORGANS ARE SURPRISINGLY GENERIC, INVOLVING GENERATION OF FIBROBLASTS AND MYOFIBROBLASTS BY DIFFERENTIATION PROCESSES THAT REQUIRE EXTENSIVE ALTERATIONS IN GENE EXPRESSION. THIS PROCESS AND INDEED PHENOTYPE OF CELLS ARE ORCHESTRATED BY THE COMBINED INFLUENCES OF MOLECULAR COMPONENTS OF EPIGENOME INCLUDING DNA METHYLATION, VAST ARRAY OF POSTTRANSLATIONAL MODIFICATIONS OF THE HISTONE PROTEIN CONSTITUENTS OF CHROMATIN AND REGULATORY NONCODING RNAS OF WHICH MICRORNAS (MIRS) ARE THE MOST EXTENSIVELY STUDIED. RECENT FINDINGS: NUMEROUS STUDIES FROM THE LAST 12 MONTHS SHOW ALL THE THREE EPIGENETIC MECHANISMS TO BE REGULATING GENERATION AND APOPTOSIS OF MYOFIBROBLASTS IN ORGANS AFFECTED BY PERTURBED WOUND HEALING. FURTHERMORE, THESE MECHANISMS ARE INVOLVED IN FIBROTIC DISEASE ITSELF, WITH SOME MIRS AND EPIGENETIC DRUGS BEING TESTED FOR THEIR THERAPEUTIC POTENTIAL. SUMMARY: FIELDS OF WOUND HEALING AND FIBROSIS WILL BE ENRICHED OVER THE NEXT DECADE BY PLETHORA OF NEW INFORMATION REGARDING EPIGENETIC CONTROL MECHANISMS WHICH WILL HOPEFULLY PROVIDE NEW ADVANCES IN DIAGNOSTICS AND PROGNOSTICS. WITH THE DESIGN OF EVER MORE SPECIFIC EPIGENETIC DRUGS, WE MAY IMPROVE OUR ABILITY TO THERAPEUTICALLY OPTIMIZE WOUND HEALING AND PREVENT FIBROSIS IN CHRONIC DISEASE AND AGEING. 2013 16 4575 25 MYOFIBROBLASTS. PURPOSE OF REVIEW: INTEREST IN THE MYOFIBROBLAST AS A KEY PLAYER IN PROPAGATION OF CHRONIC PROGRESSIVE FIBROSIS CONTINUES TO ELICIT MANY PUBLICATIONS, WITH FOCUS ON ITS CELLULAR ORIGINS AND THE MECHANISMS UNDERPINNING THEIR DIFFERENTIATION AND/OR TRANSITION. THE OBJECTIVE OF THE REVIEW IS TO HIGHLIGHT THIS RECENT PROGRESS. RECENT FINDINGS: THE EPITHELIAL ORIGIN OF THE MYOFIBROBLAST IN FIBROSIS HAS BEEN CHALLENGED BY RECENT STUDIES, WITH THE PERICYTE SUGGESTED AS A POSSIBLE PRECURSOR INSTEAD. ADDITIONAL SIGNALING PATHWAYS, INCLUDING NOTCH, WNT, AND HEDGEHOG, ARE IMPLICATED IN MYOFIBROBLAST DIFFERENTIATION. THE IMPORTANCE OF NADPH OXIDASE 4 WAS HIGHLIGHTED RECENTLY TO SUGGEST A POTENTIAL LINK BETWEEN CELLULAR/OXIDATIVE STRESS AND THE GENESIS OF THE MYOFIBROBLAST. RECENT OBSERVATIONS ON THE IMPORTANCE OF LYSOPHOSPHATIDIC ACID IN FIBROSIS SUGGEST THAT THIS MAY BE DUE, IN PART, TO ITS ABILITY TO REGULATE MYOFIBROBLAST DIFFERENTIATION. FINALLY, THERE IS INCREASING EVIDENCE FOR THE ROLE OF EPIGENETIC MECHANISMS IN REGULATING MYOFIBROBLAST DIFFERENTIATION, INCLUDING DNA METHYLATION AND MIRNA REGULATION OF GENE EXPRESSION. SUMMARY: THESE RECENT DISCOVERIES OPEN UP A WHOLE NEW ARRAY OF POTENTIAL TARGETS FOR NOVEL ANTIFIBROTIC THERAPIES. THIS IS OF SPECIAL IMPORTANCE GIVEN THE CURRENT BLEAK OUTLOOK FOR CHRONIC PROGRESSIVE FIBROTIC DISEASES, SUCH AS SCLERODERMA, DUE TO LACK OF EFFECTIVE THERAPIES. 2013 17 4976 31 PATHOPHYSIOLOGICAL MECHANISMS OF HEPATIC STELLATE CELLS ACTIVATION IN LIVER FIBROSIS. LIVER FIBROSIS IS A COMPLEX PATHOLOGICAL PROCESS CONTROLLED BY A VARIETY OF CELLS, MEDIATORS AND SIGNALING PATHWAYS. HEPATIC STELLATE CELLS PLAY A CENTRAL ROLE IN THE DEVELOPMENT OF LIVER FIBROSIS. IN CHRONIC LIVER DISEASE, HEPATIC STELLATE CELLS UNDERGO DRAMATIC PHENOTYPIC ACTIVATION AND ACQUIRE FIBROGENIC PROPERTIES. THIS REVIEW FOCUSES ON THE PATHOPHYSIOLOGICAL MECHANISMS OF HEPATIC STELLATE CELLS ACTIVATION IN LIVER FIBROSIS. THEY ENTER THE CELL CYCLE UNDER THE INFLUENCE OF VARIOUS TRIGGERS. THE "INITIATION" PHASE OF HEPATIC STELLATE CELLS ACTIVATION OVERLAPS AND CONTINUES WITH THE "PERPETUATION" PHASE, WHICH IS CHARACTERIZED BY A PRONOUNCED INFLAMMATORY AND FIBROGENIC REACTION. THIS IS FOLLOWED BY A RESOLUTION PHASE IF THE INJURY SUBSIDES. KNOWLEDGE OF THESE PATHOPHYSIOLOGICAL MECHANISMS PAVED THE WAY FOR DRUGS AIMED AT PREVENTING THE DEVELOPMENT AND PROGRESSION OF LIVER FIBROSIS. IN THIS RESPECT, IMPAIRMENTS IN INTRACELLULAR SIGNALING, EPIGENETIC CHANGES AND CELLULAR STRESS RESPONSE CAN BE THE TARGETS OF THERAPY WHERE THE GOAL IS TO DEACTIVATE HEPATIC STELLATE CELLS. POTENTIAL ANTIFIBROTIC THERAPY MAY FOCUS ON INDUCING HEPATIC STELLATE CELLS TO RETURN TO AN INACTIVE STATE THROUGH CELLULAR AGING, APOPTOSIS, AND/OR CLEARANCE BY IMMUNE CELLS, AND SERVE AS POTENTIAL ANTIFIBROTIC THERAPY. IT IS ESPECIALLY IMPORTANT TO PREVENT THE FORMATION OF LIVER CIRRHOSIS SINCE THE ONLY RADICAL APPROACH TO ITS TREATMENT IS LIVER TRANSPLANTATION WHICH CAN BE PERFORMED IN ONLY A LIMITED NUMBER OF COUNTRIES. 2022 18 1255 31 CURRENT STATUS OF NOVEL ANTIFIBROTIC THERAPIES IN PATIENTS WITH CHRONIC LIVER DISEASE. FIBROSIS ACCUMULATION IS A DYNAMIC PROCESS RESULTING FROM A WOUND-HEALING RESPONSE TO ACUTE OR CHRONIC LIVER INJURY OF ALL CAUSES. THE CASCADE STARTS WITH HEPATOCYTE NECROSIS AND APOPTOSIS, WHICH INSTIGATE INFLAMMATORY SIGNALING BY CHEMOKINES AND CYTOKINES, RECRUITMENT OF IMMUNE CELL POPULATIONS, AND ACTIVATION OF FIBROGENIC CELLS, CULMINATING IN THE DEPOSITION OF EXTRACELLULAR MATRIX. THESE KEY ELEMENTS, ALONG WITH PATHWAYS OF TRANSCRIPTIONAL AND EPIGENETIC REGULATION, REPRESENT FERTILE THERAPEUTIC TARGETS. NEW THERAPIES INCLUDE DRUGS SPECIFICALLY DESIGNED AS ANTIFIBROTICS, AS WELL AS DRUGS ALREADY AVAILABLE WITH WELL-ESTABLISHED SAFETY PROFILES, WHOSE MECHANISM OF ACTION MAY ALSO BE ANTIFIBROTIC. AT THE SAME TIME, THE DEVELOPMENT OF NONINVASIVE FIBROGENIC MARKERS, AND TECHNIQUES (E.G. FIBROSCAN), AS WELL AS COMBINED SCORING SYSTEMS INCORPORATING SERUM AND CLINICAL FEATURES WILL ALLOW IMPROVED ASSESSMENT OF THERAPY RESPONSE. IN AGGREGATE, THE ADVANCES IN THE ELUCIDATION OF THE BIOLOGY OF FIBROSIS, COMBINED WITH IMPROVED TECHNOLOGIES FOR ASSESSMENT WILL PROVIDE A COMPREHENSIVE FRAMEWORK FOR DESIGN OF ANTIFIBROTICS AND THEIR ANALYSIS IN WELL-DESIGNED CLINICAL TRIALS. THESE EFFORTS MAY ULTIMATELY YIELD SUCCESS IN HALTING THE PROGRESSION OF, OR REVERSING, LIVER FIBROSIS. 2011 19 4738 35 NOVEL FIBROBLAST PHENOTYPES IN HOMEOSTASIS AND CHRONIC INFLAMMATION: FROM FUNCTIONS TO POTENTIAL REGULATORS. FIBROBLASTS ARE ESSENTIAL COMPONENTS OF THE STROMA, SUSTAINING A VARIETY OF TISSUES AND BEING KEY TO THE PROCESS OF TISSUE REPAIR AFTER INJURY. THEIR ROLE IN TISSUE REPAIR HAS BEEN ATTRIBUTED TO THEIR ABILITY TO ACQUIRE A CONTRACTILE, EXTRACELLULAR MATRIX-PRODUCING PHENOTYPE KNOWN AS MYOFIBROBLASTS. THIS PROPERTY IS PRIMARILY DEPENDENT ON THEIR RESPONSE TO THE PLEIOTROPIC CYTOKINE TRANSFORMING GROWTH FACTOR-BETA1. UNTIL RECENTLY, THE POTENTIAL ROLE OF FIBROBLASTS IN OTHER HOMEOSTATIC AND DISEASE-RELATED PROCESSES WAS LESS WELL UNDERSTOOD. ALTHOUGH IN VITRO STUDIES INDICATED THAT FIBROBLASTS ARE ABLE TO RESPOND TO AND SECRETE INFLAMMATORY MEDIATORS, DEFINITIVE EVIDENCE OF THEIR CONTRIBUTION TO CHRONIC INFLAMMATION WAS LIMITED. HOWEVER, THE EMERGENCE OF TECHNIQUES THAT ALLOW EXPLORATION OF TISSUES AT THE SINGLE CELL LEVEL HAS CHALLENGED THE PREVIOUS PARADIGMS ON FIBROBLAST IDENTITY AND FUNCTIONS, AND HAS LED TO THE DISCOVERY OF SIGNIFICANT DIVERSITY, SHOWING THE PRESENCE OF FIBROBLASTS WITH ALTERNATE TRANSCRIPTIONAL PROFILES IN A VARIETY OF TISSUES. THESE STUDIES HAVE ALSO SUGGESTED POTENTIAL ROLES OF NOVEL FIBROBLAST SUBTYPES AS REGULATORS OF EPITHELIAL HOMEOSTASIS AND RENEWAL, INFLAMMATORY CELL INFILTRATION AND ACTIVATION, AND ANTIGEN PRESENTATION. HERE, WE PROVIDE A COMPREHENSIVE REVIEW OF THE RECENT LITERATURE ON FIBROBLAST DIVERSITY IN THE DIGESTIVE TRACT, SKIN, LUNGS AND JOINTS. WE ALSO REVIEW EVIDENCE OF THEIR CONTRIBUTION TO THE REGULATION OF HOMEOSTASIS AND CHRONIC INFLAMMATION, AS WELL AS THEIR INTERACTIONS WITH OTHER CELLS IN VARIOUS TISSUE COMPARTMENTS. WE DISCUSS EVIDENCE OF DIFFERENT FACTORS INVOLVED IN THE CONTROL OF FIBROBLAST FUNCTION, ADDRESSING THE ROLE OF VARIOUS CYTOKINES, TRANSCRIPTION FACTORS AND EPIGENETIC CHANGES, AS WELL AS MICROENVIRONMENTAL FACTORS, INCLUDING EXTRACELLULAR MATRIX STIFFNESS, HYPOXIA, AND METABOLIC SHIFTS. 2023 20 2341 23 EPIGENETIC REGULATION OF LIVER FIBROSIS. FIBROSIS IS A COMMON AND IMPORTANT PATHOLOGY ASSOCIATED WITH PROGRESSIVE CHRONIC LIVER DISEASES AND UNDERLIES THE DEVELOPMENT OF CIRRHOSIS AND HEPATOCELLULAR CARCINOMA. RESEARCH INTO THE MOLECULAR REGULATION OF FIBROSIS HAS DISCOVERED THAT IT IS UNDER THE CONTROL OF A NUMBER OF EPIGENETIC MECHANISMS INCLUDING DNA METHYLATION, HISTONE MODIFICATIONS AND THE ACTIVITIES OF NON-CODING RNAS. A DEEPER UNDERSTANDING OF HOW EPIGENETIC REGULATORS SUCH AS DNA METHYLTRANSERASES, METHYL-DNA BINDING PROTEINS, HISTONE MODIFYING ENZYMES AND REGULATORY RNA MOLECULES IMPACT ON THE FIBROGENIC PROCESS IS EXPECTED TO RESULT IN NEW BIOMARKERS FOR DISEASE PROGRESSION AS WELL AS NOVEL THERAPEUTIC TARGETS. THE AIM OF THIS MINI-REVIEW IS TO BRIEFLY INTRODUCE THE READER TO THE MAJOR EPIGENETIC REGULATORS SO FAR IDENTIFIED AS BEING IMPLICATED IN FIBROSIS. 2015