1 3931 84 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 2 4132 25 MECHANISMS OF HEPATIC FIBROGENESIS. SUBSTANTIAL IMPROVEMENTS IN THE TREATMENT OF CHRONIC LIVER DISEASE HAVE ACCELERATED INTEREST IN UNCOVERING THE MECHANISMS UNDERLYING HEPATIC FIBROSIS AND ITS RESOLUTION. ACTIVATION OF RESIDENT HEPATIC STELLATE CELLS INTO PROLIFERATIVE, CONTRACTILE, AND FIBROGENIC CELLS IN LIVER INJURY REMAINS A DOMINANT THEME DRIVING THE FIELD. HOWEVER, SEVERAL NEW AREAS OF RAPID PROGRESS IN THE PAST 5-10 YEARS ALSO HAVE TAKEN ROOT, INCLUDING: (1) IDENTIFICATION OF DIFFERENT FIBROGENIC POPULATIONS APART FROM RESIDENT STELLATE CELLS, FOR EXAMPLE, PORTAL FIBROBLASTS, FIBROCYTES, AND BONE-MARROW-DERIVED CELLS, AS WELL AS CELLS DERIVED FROM EPITHELIAL MESENCHYMAL TRANSITION; (2) EMERGENCE OF STELLATE CELLS AS FINELY REGULATED DETERMINANTS OF HEPATIC INFLAMMATION AND IMMUNITY; (3) ELUCIDATION OF MULTIPLE PATHWAYS CONTROLLING GENE EXPRESSION DURING STELLATE CELL ACTIVATION INCLUDING TRANSCRIPTIONAL, POST-TRANSCRIPTIONAL, AND EPIGENETIC MECHANISMS; (4) RECOGNITION OF DISEASE-SPECIFIC PATHWAYS OF FIBROGENESIS; (5) RE-EMERGENCE OF HEPATIC MACROPHAGES AS DETERMINANTS OF MATRIX DEGRADATION IN FIBROSIS RESOLUTION AND THE IMPORTANCE OF MATRIX CROSS-LINKING AND SCAR MATURATION IN DETERMINING REVERSIBILITY; AND (6) HINTS THAT HEPATIC STELLATE CELLS MAY CONTRIBUTE TO HEPATIC STEM CELL BEHAVIOR, CANCER, AND REGENERATION. CLINICAL AND TRANSLATIONAL IMPLICATIONS OF THESE ADVANCES HAVE BECOME CLEAR, AND HAVE BEGUN TO IMPACT SIGNIFICANTLY ON THE MANAGEMENT AND OUTLOOK OF PATIENTS WITH CHRONIC LIVER DISEASE. 2008 3 3245 23 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 4 5939 31 TARGETING MECHANOTRANSDUCTION AT THE TRANSCRIPTIONAL LEVEL: YAP AND BRD4 ARE NOVEL THERAPEUTIC TARGETS FOR THE REVERSAL OF LIVER FIBROSIS. LIVER FIBROSIS IS THE RESULT OF A DEREGULATED WOUND HEALING PROCESS CHARACTERIZED BY THE EXCESSIVE DEPOSITION OF EXTRACELLULAR MATRIX. HEPATIC STELLATE CELLS (HSCS), WHICH ARE ACTIVATED IN RESPONSE TO LIVER INJURY, ARE THE MAJOR SOURCE OF EXTRACELLULAR MATRIX AND DRIVE THE WOUND HEALING PROCESS. HOWEVER, CHRONIC LIVER DAMAGE LEADS TO PERPETUAL HSC ACTIVATION, PROGRESSIVE FORMATION OF PATHOLOGICAL SCAR TISSUE AND ULTIMATELY, CIRRHOSIS AND ORGAN FAILURE. HSC ACTIVATION IS TRIGGERED LARGELY IN RESPONSE TO MECHANOSIGNALING FROM THE MICROENVIRONMENT, WHICH INDUCES A PROFIBROTIC NUCLEAR TRANSCRIPTION PROGRAM THAT PROMOTES HSC PROLIFERATION AND EXTRACELLULAR MATRIX SECRETION THEREBY SETTING UP A POSITIVE FEEDBACK LOOP LEADING TO MATRIX STIFFENING AND SELF-SUSTAINED, PATHOLOGICAL, HSC ACTIVATION. DESPITE THE SIGNIFICANT PROGRESS IN OUR UNDERSTANDING OF LIVER FIBROSIS, THE MOLECULAR MECHANISMS THROUGH WHICH THE EXTRACELLULAR MATRIX PROMOTES HSC ACTIVATION ARE NOT WELL UNDERSTOOD AND NO EFFECTIVE THERAPIES HAVE BEEN APPROVED TO DATE THAT CAN TARGET THIS EARLY, REVERSIBLE, STAGE IN LIVER FIBROSIS. SEVERAL NEW LINES OF INVESTIGATION NOW PROVIDE IMPORTANT INSIGHT INTO THIS AREA OF STUDY AND IDENTIFY TWO NUCLEAR TARGETS WHOSE INHIBITION HAS THE POTENTIAL OF REVERSING LIVER FIBROSIS BY INTERFERING WITH HSC ACTIVATION: YES-ASSOCIATED PROTEIN (YAP), A TRANSCRIPTIONAL CO-ACTIVATOR AND EFFECTOR OF THE MECHANOSENSITIVE HIPPO PATHWAY, AND BROMODOMAIN-CONTAINING PROTEIN 4 (BRD4), AN EPIGENETIC REGULATOR OF GENE EXPRESSION. YAP AND BRD4 ACTIVITY IS INDUCED IN RESPONSE TO MECHANICAL STIMULATION OF HSCS AND EACH PROTEIN INDEPENDENTLY CONTROLS WAVES OF EARLY GENE EXPRESSION NECESSARY FOR HSC ACTIVATION. SIGNIFICANTLY, INHIBITION OF EITHER PROTEIN CAN REVERT THE CHRONIC ACTIVATION OF HSCS AND IMPEDE PATHOLOGICAL PROGRESSION OF LIVER FIBROSIS IN CLINICALLY RELEVANT MODEL SYSTEMS. IN THIS REVIEW WE WILL DISCUSS THE ROLES OF THESE NUCLEAR CO-ACTIVATORS IN HSC ACTIVATION, THEIR MECHANISM OF ACTION IN THE FIBROTIC PROCESS IN THE LIVER AND OTHER ORGANS, AND THE POTENTIAL OF TARGETING THEIR ACTIVITY WITH SMALL MOLECULE DRUGS FOR FIBROSIS REVERSAL. 2016 5 2502 26 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 6 3512 25 IDIOPATHIC PULMONARY FIBROSIS. IDIOPATHIC PULMONARY FIBROSIS IS A DEVASTATING, AGE-RELATED LUNG DISEASE OF UNKNOWN CAUSE THAT HAS FEW TREATMENT OPTIONS. THIS DISEASE WAS ONCE THOUGHT TO BE A CHRONIC INFLAMMATORY PROCESS, BUT CURRENT EVIDENCE INDICATES THAT THE FIBROTIC RESPONSE IS DRIVEN BY ABNORMALLY ACTIVATED ALVEOLAR EPITHELIAL CELLS (AECS). THESE CELLS PRODUCE MEDIATORS THAT INDUCE THE FORMATION OF FIBROBLAST AND MYOFIBROBLAST FOCI THROUGH THE PROLIFERATION OF RESIDENT MESENCHYMAL CELLS, ATTRACTION OF CIRCULATING FIBROCYTES, AND STIMULATION OF THE EPITHELIAL TO MESENCHYMAL TRANSITION. THE FIBROBLAST AND MYOFIBROBLAST FOCI SECRETE EXCESSIVE AMOUNTS OF EXTRACELLULAR MATRIX, MAINLY COLLAGENS, RESULTING IN SCARRING AND DESTRUCTION OF THE LUNG ARCHITECTURE. THE MECHANISMS THAT LINK IDIOPATHIC PULMONARY FIBROSIS WITH AGEING AND ABERRANT EPITHELIAL ACTIVATION ARE UNKNOWN; EVIDENCE SUGGESTS THAT THE ABNORMAL RECAPITULATION OF DEVELOPMENTAL PATHWAYS AND EPIGENETIC CHANGES HAVE A ROLE. IN THIS SEMINAR, WE REVIEW RECENT DATA ON THE CLINICAL COURSE, THERAPEUTIC OPTIONS, AND UNDERLYING MECHANISMS THOUGHT TO BE INVOLVED IN THE PATHOGENESIS OF IDIOPATHIC PULMONARY FIBROSIS. 2011 7 4749 24 NOVEL PROSPECTS FOR SCARLESS WOUND HEALING: THE ROLES OF MYOFIBROBLASTS AND ADIPOCYTES. DISTURBANCES OR DEFECTS IN THE PROCESS OF WOUND REPAIR CAN DISRUPT THE DELICATE BALANCE OF CELLS AND MOLECULES NECESSARY FOR COMPLETE WOUND HEALING, THUS LEADING TO CHRONIC WOUNDS OR FIBROTIC SCARS. MYOFIBROBLASTS ARE ONE OF THE MOST IMPORTANT CELLS INVOLVED IN FIBROTIC SCARS, AND REPROGRAMMING PROVIDES A POTENTIAL AVENUE TO INCREASE MYOFIBROBLAST CLEARANCE. ALTHOUGH MYOFIBROBLASTS HAVE LONG BEEN RECOGNIZED AS TERMINALLY DIFFERENTIATED CELLS, RECENT STUDIES HAVE SHOWN THAT MYOFIBROBLASTS HAVE THE CAPACITY TO BE REPROGRAMMED INTO ADIPOCYTES. THIS REVIEW INTENDS TO SUMMARIZE THE POTENTIAL OF REPROGRAMMING MYOFIBROBLASTS INTO ADIPOCYTES. WE WILL DISCUSS MYOFIBROBLAST LINEAGE TRACING, AS WELL AS THE KNOWN MECHANISMS UNDERLYING ADIPOCYTE REGENERATION FROM MYOFIBROBLASTS. IN ADDITION, WE INVESTIGATED DIFFERENT CHANGES IN MYOFIBROBLAST GENE EXPRESSION, TRANSCRIPTIONAL REGULATORS, SIGNALLING PATHWAYS AND EPIGENETIC REGULATORS DURING SKIN WOUND HEALING. IN THE FUTURE, MYOFIBROBLAST REPROGRAMMING IN WOUND HEALING WILL BE BETTER UNDERSTOOD AND APPRECIATED, WHICH MAY PROVIDE NEW IDEAS FOR THE TREATMENT OF SCARLESS WOUND HEALING. 2022 8 2817 23 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 9 6910 21 [TRANSFORMING GROWTH FACTOR-BETA AND RENAL FIBROSIS]. TRANSFORMING GROWTH FACTOR-BETA (TGF-BETA) IS A DRIVING FORCE OF RENAL FIBROSIS, WHICH MAY LEAD TO CHRONIC KIDNEY DISEASES AND EVEN END STAGE RENAL DISEASES. BY ACTIVATING CANONICAL AND NON-CANONICAL SIGNALING PATHWAYS, TGF-BETA PROMOTES THE SYNTHESIS OF EXTRACELLULAR MATRIX WHILE PREVENTING THEIR DEGRADATION. IN THE INJURED KIDNEY, TGF-BETA INDUCES APOPTOSIS, PROLIFERATION AND FIBROTIC RESPONSE OF RENAL CELLS INCLUDING EPITHELIAL CELLS, ENDOTHELIAL CELLS, PODOCYTES, FIBROBLASTS, PERICYTES AND MACROPHAGES, AND IT ALSO PROMOTES TRANSDIFFERENTIATION, ACTIVATION AND PROLIFERATION OF MYOFIBROBLASTS. ADDITIONALLY, TGF-BETA EXERTS PROFIBROTIC EFFECTS BY INTERPLAYING WITH OTHER SIGNALING PATHWAYS LIKE BMP-7, WNT/BETA-CATENIN AND MAP KINASE. SMAD3 IS THE CENTRAL PATHOLOGICAL GENE IN RENAL FIBROSIS, AND EPIGENETIC REGULATION OF TGF-BETA/SMAD3 IS A HOT TOPIC IN KIDNEY FIELD. ALTHOUGH DIRECT TARGETING TGF-BETA MAY CAUSE SIDE EFFECTS INCLUDING TUMORIGENESIS AND IMMUNE DISEASES, THE THERAPEUTIC STRATEGIES TARGETING THE BALANCE OF DOWNSTREAM SMAD3 AND SMAD7 MAY PREVENT OR DELAY THE PROGRESSION OF FIBROTIC KIDNEY DISEASE. 2018 10 4448 31 MOLECULAR MECHANISM AND TREATMENT OF VIRAL HEPATITIS-RELATED LIVER FIBROSIS. HEPATIC FIBROSIS IS A WOUND-HEALING RESPONSE TO VARIOUS CHRONIC STIMULI, INCLUDING VIRAL HEPATITIS B OR C INFECTION. ACTIVATED MYOFIBROBLASTS, PREDOMINANTLY DERIVED FROM THE HEPATIC STELLATE CELLS (HSCS), REGULATE THE BALANCE BETWEEN MATRIX METALLOPROTEINASES AND THEIR TISSUE INHIBITORS TO MAINTAIN EXTRACELLULAR MATRIX HOMEOSTASIS. TRANSFORMING GROWTH FACTOR-BETA AND PLATELET-DERIVED GROWTH FACTOR ARE CLASSIC PROFIBROGENIC SIGNALS THAT ACTIVATE HSC PROLIFERATION. IN ADDITION, PROINFLAMMATORY CYTOKINES AND CHEMOKINES COORDINATE MACROPHAGES, T CELLS, NK/NKT CELLS, AND LIVER SINUSOIDAL ENDOTHELIAL CELLS IN COMPLEX FIBROGENIC AND REGRESSION PROCESSES. IN ADDITION, FIBROGENESIS INVOLVES ANGIOGENESIS, METABOLIC REPROGRAMMING, AUTOPHAGY, MICRORNA, AND EPIGENETIC REGULATIONS. HEPATIC INFLAMMATION IS THE DRIVING FORCE BEHIND LIVER FIBROSIS; HOWEVER, HOST SINGLE NUCLEOTIDE POLYMORPHISMS AND VIRAL FACTORS, INCLUDING THE GENOTYPE, VIRAL LOAD, VIRAL MUTATION, AND VIRAL PROTEINS, HAVE BEEN ASSOCIATED WITH FIBROSIS PROGRESSION. ELIMINATING THE UNDERLYING ETIOLOGY IS THE MOST CRUCIAL ANTIFIBROTIC THERAPY. GROWING EVIDENCE HAS INDICATED THAT PERSISTENT VIRAL SUPPRESSION WITH ANTIVIRAL THERAPY CAN RESULT IN FIBROSIS REGRESSION, REDUCED LIVER DISEASE PROGRESSION, DECREASED HEPATOCELLULAR CARCINOMA, AND IMPROVED CHANCES OF SURVIVAL. PRECLINICAL STUDIES AND CLINICAL TRIALS ARE CURRENTLY EXAMINING SEVERAL INVESTIGATIONAL AGENTS THAT TARGET KEY FIBROGENIC PATHWAYS; THE RESULTS ARE PROMISING AND SHED LIGHT ON THIS DEBILITATING ILLNESS. 2014 11 4501 25 MORPHOGENS AND HEPATIC STELLATE CELL FATE REGULATION IN CHRONIC LIVER DISEASE. HEPATIC STELLATE CELLS (HSC) ARE THE LIVER MESENCHYMAL CELL TYPE WHICH RESPONDS TO HEPATOCELLULAR DAMAGE AND PARTICIPATES IN WOUND HEALING. ALTHOUGH HSC MYOFIBROBLASTIC TRANS-DIFFERENTIATION (ACTIVATION) IS IMPLICATED IN EXCESSIVE EXTRACELLULAR MATRIX DEPOSITION, MOLECULAR UNDERSTANDING OF THIS PHENOTYPIC SWITCH FROM THE VIEWPOINT OF CELL FATE REGULATION IS LIMITED. RECENT STUDIES DEMONSTRATE THE ROLES OF ANTI-ADIPOGENIC MORPHOGENS (WNT, NECDIN, SHH) IN EPIGENETIC REPRESSION OF THE HSC DIFFERENTIATION GENE PPARGAMMA AS A CAUSAL EVENT IN HSC ACTIVATION. THESE MORPHOGENS HAVE POSITIVE CROSS-INTERACTIONS WHICH CONVERGE TO EPIGENETIC REPRESSION OF PPARGAMMA INVOLVING THE METHYL-CPG BINDING PROTEIN MECP2. HOWEVER, THESE MORPHOGENS EXPRESSED BY ACTIVATED HSC MAY ALSO PARTICIPATE IN CROSS-TALK BETWEEN HSC AND HEPATOBLASTS/HEPATOCYTES TO SUPPORT LIVER REGENERATION, AND THEIR ABERRANT REGULATION MAY CONTRIBUTE TO LIVER TUMORIGENESIS. IMPLICATIONS OF HSC-DERIVED MORPHOGENS IN THESE POSSIBILITIES ARE DISCUSSED. 2012 12 3674 27 INFLAMMATION AND DYSREGULATED FIBROBLAST PROLIFERATION--NEW MECHANISMS? IDIOPATHIC PULMONARY FIBROSIS (IPF) IS A DEVASTATING, AGE-RELATED LUNG DISEASE OF UNKNOWN CAUSE THAT HAS FEW TREATMENT OPTIONS. ONCE THOUGHT TO BE A CHRONIC INFLAMMATORY PROCESS, CURRENT EVIDENCE INDICATES THAT THE FIBROTIC RESPONSE MAY PRIMARILY BE DRIVEN BY ABNORMALLY ACTIVATED ALVEOLAR EPITHELIAL CELLS AND THE UNDERLYING MESENCHYME. THE MEDIATORS PRODUCED AND PRESENT IN THIS MICROENVIRONMENT INDUCE THE FORMATION OF FIBROBLAST FOCI THROUGH THE PROLIFERATION OF RESIDENT MESENCHYMAL CELLS, ATTRACTION OF CIRCULATING FIBROCYTES, AND STIMULATION OF EPITHELIAL TO MESENCHYMAL TRANSITION. THE FIBROBLAST AND MYOFIBROBLAST FOCI SECRETE EXCESSIVE AMOUNTS OF EXTRACELLULAR MATRIX, MAINLY COLLAGENS, RESULTING IN SCARRING AND DESTRUCTION OF THE LUNG ARCHITECTURE. THE DETAILED MECHANISMS THAT LINK IPF WITH AGEING AND ABERRANT EPITHELIAL ACTIVATION ARE UNKNOWN, BUT SOME EVIDENCE SUGGESTS THAT THE ABNORMAL RECAPITULATION OF DEVELOPMENTAL PATHWAYS AND EPIGENETIC CHANGES MAY PLAY A ROLE. THIS REVIEW PROVIDES A BRIEF SYNOPSIS OF HIGHLIGHTS IN THE CURRENT UNDERSTANDING OF THE PATHOPHYSIOLOGY OF IPF, AS WELL AS NOVEL THERAPEUTICS BEING EXPLORED IN CLINICAL TRIALS FOR THE TREATMENT OF THIS DEVASTATING DISEASE. 2013 13 3184 25 HARNESSING METABOLISM OF HEPATIC MACROPHAGES TO AID LIVER REGENERATION. LIVER REGENERATION IS A DYNAMIC AND REGULATED PROCESS THAT INVOLVES INFLAMMATION, GRANULATION, AND TISSUE REMODELING. HEPATIC MACROPHAGES, ABUNDANTLY DISTRIBUTED IN THE LIVER, ARE ESSENTIAL COMPONENTS THAT ACTIVELY PARTICIPATE IN EACH STEP TO ORCHESTRATE LIVER REGENERATION. IN THE HOMEOSTATIC LIVER, RESIDENT MACROPHAGES (KUPFFER CELLS) ACQUIRE A TOLEROGENIC PHENOTYPE AND CONTRIBUTE TO IMMUNOLOGICAL TOLERANCE. FOLLOWING TOXICITY-INDUCED DAMAGE OR PHYSICAL RESECTION, KUPFFER CELLS AS WELL AS MONOCYTE-DERIVED MACROPHAGES CAN BE ACTIVATED AND PROMOTE AN INFLAMMATORY PROCESS THAT SUPPORTS THE SURVIVAL AND ACTIVATION OF HEPATIC MYOFIBROBLASTS AND THUS PROMOTES SCAR TISSUE FORMATION. SUBSEQUENTLY, THESE MACROPHAGES, IN TURN, EXHIBIT THE ANTI-INFLAMMATORY EFFECTS CRITICAL TO EXTRACELLULAR MATRIX REMODELING DURING THE RESOLUTION STAGE. HOWEVER, CONTINUOUS DAMAGE-INDUCED CHRONIC INFLAMMATION GENERALLY LEADS TO HEPATIC MACROPHAGE DYSFUNCTION, WHICH EXACERBATES HEPATOCELLULAR INJURY AND TRIGGERS FURTHER LIVER FIBROSIS AND EVEN CIRRHOSIS. EMERGING MACROPHAGE-TARGETING STRATEGIES HAVE SHOWN EFFICACY IN BOTH PRECLINICAL AND CLINICAL STUDIES. INCREASING EVIDENCE INDICATES THAT METABOLIC REWIRING PROVIDES SUBSTRATES FOR EPIGENETIC MODIFICATION, WHICH ENDOWS MONOCYTES/MACROPHAGES WITH PROLONGED "INNATE IMMUNE MEMORY". THEREFORE, IT IS REASONABLE TO CONCEIVE NOVEL THERAPEUTIC STRATEGIES FOR METABOLICALLY REPROGRAMMING MACROPHAGES AND THUS MEDIATE A HOMEOSTATIC OR REPARATIVE PROCESS FOR HEPATIC INFLAMMATION MANAGEMENT AND LIVER REGENERATION. 2023 14 4976 30 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 15 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 16 5805 37 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 17 699 24 BROMODOMAIN PROTEIN 4 IS A KEY MOLECULAR DRIVER OF TGFBETA1-INDUCED HEPATIC STELLATE CELL ACTIVATION. LIVER FIBROSIS IS CHARACTERIZED BY THE EXCESSIVE DEPOSITION OF EXTRACELLULAR MATRIX IN LIVER. CHRONIC LIVER INJURY INDUCES THE ACTIVATION OF HEPATIC STELLATE CELL (HSCS), A KEY STEP IN LIVER FIBROGENESIS. THE ACTIVATED HSC IS THE PRIMARY SOURCE OF ECM AND CONTRIBUTES SIGNIFICANTLY TO LIVER FIBROSIS. TGFBETA1 IS THE MOST POTENT PRO-FIBROTIC CYTOKINE. BROMODOMAIN PROTEIN 4 (BRD4), AN EPIGENETIC READER OF HISTONE ACETYLATION MARKS, WAS CRUCIAL FOR PROFIBROTIC GENE EXPRESSION IN HSCS. THE PRESENT STUDY AIMED TO INVESTIGATE THE ROLES OF BRD4 IN TGFBETA1-DEPENDENT HSC ACTIVATION AND LIVER FIBROSIS, FOCUSING ON TGFBETA1-INDUCED ALTERATIONS OF THE LEVELS OF THE FIBROTIC-RELATED IMPORTANT PROTEINS IN HSCS BY EMPLOYING THE HETEROZYGOUS TGFBETA1 KNOCKOUT MICE AND BRD4 KNOCKDOWN IN VIVO AND IN VITRO. RESULTS REVEALED THAT BRD4 PROTEIN LEVEL WAS SIGNIFICANTLY UPREGULATED BY TGFBETA1 AND BRD4 KNOCKDOWN REDUCED TGFBETA1-INDUCED HSC ACTIVATION AND LIVER FIBROSIS. BRD4 WAS REQUIRED FOR THE INFLUENCES OF TGFBETA1 ON PDGFBETA RECEPTOR AND ON THE PATHWAYS OF SMAD3, STAT3, AND AKT. BRD4 ALSO MEDIATED TGFBETA1-INDUCED INCREASES IN HISTONE ACETYLTRANSFERASE P300, THE PIVOTAL PRO-INFLAMMATORY NFKB P65, AND TISSUE INHIBITOR OF METALLOPROTEINASE 1 WHEREAS BRD4 REDUCED CASPASE-3 PROTEIN LEVELS IN HSCS DURING LIVER INJURY, INDEPENDENT OF TGFBETA1. FURTHER EXPERIMENTS INDICATED THE INTERACTION BETWEEN TGFBETA1-INDUCED BRD4 AND NFKB P65 IN HSCS AND IN LIVER OF TAA-INDUCED LIVER INJURY. HUMAN CIRRHOTIC LIVERS WERE DEMONSTRATED A PARALLEL INCREASE IN THE PROTEIN LEVELS OF BRD4 AND NFKB P65 IN HSCS. THIS STUDY REVEALED THAT BRD4 WAS A KEY MOLECULAR DRIVER OF TGFBETA1-INDUCED HSC ACTIVATION AND LIVER FIBROSIS. 2023 18 1886 21 ENDOGENOUS BIOLOGICAL DRIVERS IN DIABETIC LOWER LIMB WOUNDS RECURRENCE: HYPOTHETICAL REFLECTIONS. AN IMPAIRED HEALING RESPONSE UNDERLIES DIABETIC FOOT WOUND CHRONICITY, FREQUENTLY TRANSLATING TO AMPUTATION, DISABILITY, AND MORTALITY. DIABETICS SUFFER FROM UNDERAPPRECIATED EPISODES OF POST-EPITHELIZATION ULCER RECURRENCE. RECURRENCE EPIDEMIOLOGICAL DATA ARE ALARMINGLY HIGH, SO THE ULCER IS CONSIDERED IN "REMISSION" AND NOT HEALED FROM THE TIME IT REMAINS EPITHELIALIZED. RECURRENCE MAY RESULT FROM THE COMBINED EFFECTS OF BEHAVIORAL AND ENDOGENOUS BIOLOGICAL FACTORS. ALTHOUGH THE DAMAGING ROLE OF BEHAVIORAL, CLINICAL PREDISPOSING FACTORS IS UNDEBATABLE, IT STILL REMAINS ELUSIVE IN THE IDENTIFICATION OF ENDOGENOUS BIOLOGICAL CULPRITS THAT MAY PRIME THE RESIDUAL SCAR TISSUE FOR RECURRENCE. FURTHERMORE, THE EVENT OF ULCER RECURRENCE STILL WAITS FOR THE IDENTIFICATION OF A MOLECULAR PREDICTOR. WE PROPOSE THAT ULCER RECURRENCE IS DEEPLY IMPINGED BY CHRONIC HYPERGLYCEMIA AND ITS DOWNSTREAM BIOLOGICAL EFFECTORS, WHICH ORIGINATE EPIGENETIC DRIVERS THAT ENFORCE ABNORMAL PATHOLOGIC PHENOTYPES TO DERMAL FIBROBLASTS AND KERATINOCYTES AS MEMORY CELLS. HYPERGLYCEMIA-DERIVED CYTOTOXIC REACTANTS ACCUMULATE AND MODIFY DERMAL PROTEINS, REDUCE SCAR TISSUE MECHANICAL TOLERANCE, AND DISRUPT FIBROBLAST-SECRETORY ACTIVITY. ACCORDINGLY, THE COMBINATION OF EPIGENETIC AND LOCAL AND SYSTEMIC CYTOTOXIC SIGNALERS INDUCE THE ONSET OF "AT-RISK PHENOTYPES" SUCH AS PREMATURE SKIN CELL AGING, DYSMETABOLISM, INFLAMMATORY, PRO-DEGRADATIVE, AND OXIDATIVE PROGRAMS THAT MAY ULTIMATELY CONVERGE TO SCAR CELL DEMISE. POST-EPITHELIALIZATION RECURRENCE RATE DATA ARE MISSING IN CLINICAL STUDIES OF REPUTED ULCER HEALING THERAPIES DURING FOLLOW-UP PERIODS. INTRA-ULCER INFILTRATION OF EPIDERMAL GROWTH FACTOR EXHIBITS THE MOST CONSISTENT REMISSION DATA WITH THE LOWEST RECURRENCES DURING 12-MONTH FOLLOW-UP. RECURRENCE DATA SHOULD BE REGARDED AS A VALUABLE CLINICAL ENDPOINT DURING THE INVESTIGATIONAL PERIOD FOR EACH EMERGENT HEALING CANDIDATE. 2023 19 2545 26 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 20 6623 20 UNDERSTANDING KELOID PATHOBIOLOGY FROM A QUASI-NEOPLASTIC PERSPECTIVE: LESS OF A SCAR AND MORE OF A CHRONIC INFLAMMATORY DISEASE WITH CANCER-LIKE TENDENCIES. KELOIDS ARE CONSIDERED AS BENIGN FIBROPROLIFERATIVE SKIN TUMORS GROWING BEYOND THE SITE OF THE ORIGINAL DERMAL INJURY. ALTHOUGH TRADITIONALLY VIEWED AS A FORM OF SKIN SCARRING, KELOIDS DISPLAY MANY CANCER-LIKE CHARACTERISTICS SUCH AS PROGRESSIVE UNCONTROLLED GROWTH, LACK OF SPONTANEOUS REGRESSION AND EXTREMELY HIGH RATES OF RECURRENCE. PHENOTYPICALLY, KELOIDS ARE CONSISTENT WITH NON-MALIGNANT DERMAL TUMORS THAT ARE DUE TO THE EXCESSIVE OVERPRODUCTION OF COLLAGEN WHICH NEVER METASTASIZE. WITHIN THE REMIT OF KELOID PATHOBIOLOGY, THERE IS INCREASING EVIDENCE FOR THE VARIOUS INTERPLAY OF NEOPLASTIC-PROMOTING AND SUPPRESSING FACTORS, WHICH MAY EXPLAIN ITS AGGRESSIVE CLINICAL BEHAVIOR. AMONGST THE MOST COMPELLING PARALLELS BETWEEN KELOIDS AND CANCER ARE THEIR SHARED CELLULAR BIOENERGETICS, EPIGENETIC METHYLATION PROFILES AND EPITHELIAL-TO-MESENCHYMAL TRANSITION AMONGST OTHER DISEASE BIOLOGICAL (GENOTYPIC AND PHENOTYPIC) BEHAVIORS. THIS REVIEW EXPLORES THE QUASI-NEOPLASTIC OR CANCER-LIKE PROPERTIES OF KELOIDS AND HIGHLIGHTS AREAS FOR FUTURE STUDY. 2019