1 6361 174 THE ROLE OF INNATE IMMUNITY IN THE PATHOGENESIS OF PRENEOPLASIA IN DRUG-INDUCED CHRONIC HEPATITIS BASED ON A MOUSE MODEL. INNATE IMMUNITY FACTORS SUCH AS CONVERSION OF THE 26S PROTEASOME TO FORM THE IMMUNOPROTEASOME AND THE TOLL-LIKE RECEPTOR SIGNALING PATHWAYS ARE ACTIVATED IN CHRONIC HEPATITIS INDUCED BY THE CARCINOGENIC DRUG DDC. OVER TIME, PRENEOPLASTIC HEPATOCYTE PHENOTYPES APPEAR IN THE LIVER PARENCHYMA. THESE CHANGED HEPATOCYTES EXPAND IN NUMBER BECAUSE THEY HAVE A GROWTH ADVANTAGE OVER NORMAL HEPATOCYTES WHEN RESPONDING TO CHRONIC LIVER INJURY. THE CHANGED HEPATOCYTES CAN BE IDENTIFIED USING IMMUNOFLUORESCENT ANTIBODIES TO PRENEOPLASTIC CELLS E.G. FAT10/UBD, A2 MACROGLOBULIN, GLUTATHIONE TRANSPEPTIDASE, ALPHA FETOPROTEIN, GLYCIPAN 3, FAS, AND GAMMA GLUTAMYL TRANSPEPTIDASE. THE FORMATION OF THE PRENEOPLASTIC CELLS OCCURS CONCOMITANT WITH ACTIVATION OF THE TOLL-LIKE RECEPTOR SIGNALING PATHWAYS AND THE TRANSFORMATION OF THE 26S PROTEASOME TO FORM THE IMMUNOPROTEASOME. THIS TRANSFORMATION IS IN RESPONSE TO INTERFERON STIMULATING RESPONSE ELEMENT ON THE PROMOTER OF THE FAT10/UBD GENE. NFKAPPAB, ERK, P38 AND JNK ARE ALSO UP REGULATED. SPECIFIC INHIBITORS BLOCK THESE RESPONSES IN VITRO IN A MOUSE TUMOR CELL LINE EXPOSED TO INTERFERON GAMMA. MALLORY-DENK BODIES FORM IN THESE PRENEOPLASTIC CELLS, BECAUSE OF THE DEPLETION OF THE 26S PROTEASOME DUE TO FORMATION OF THE IMMUNOPROTEASOME. THUS, MDB FORMING CELLS ARE ALSO MARKERS OF THE PRENEOPLASTIC HEPATOCYTES. THE UBD POSITIVE PRENEOPLASTIC CELLS REGRESS WHEN THE LIVER INJURY INDUCED CHRONIC HEPATITIS SUBSIDES. WHEN THE DRUG DDC IS REFED TO MICE AND CHRONIC HEPATITIS IS ACTIVATED, THE PRENEOPLASTIC CELL POPULATION EXPANDS AND MALLORY-DENK BODIES RAPIDLY REFORM. THIS RESPONSE IS REMEMBERED BY THE PRENEOPLASTIC CELLS FOR AT LEAST FOUR MONTHS INDICATING THAT AN EPIGENETIC CELLULAR MEMORY HAS FORMED IN THE PRENEOPLASTIC CELLS. THIS PROLIFERATIVE RESPONSE IS PREVENTED BY FEEDING METHYL DONORS SUCH AS S-ADENOSYLMETHIONINE OR BETAINE. DRUG FEEDING REDUCES THE METHYLATION OF H(3) K4, 9, AND 27 AND THIS RESPONSE IS PREVENTED BY FEEDING THE METHYL DONORS. AFTER 8 TO 15MONTHS OF DRUG WITHDRAWAL IN MICE THE PRENEOPLASTIC LIVER CELLS PERSIST AS SINGLE OR SMALL CLUSTERS OF CELLS IN THE LIVER LOBULES. MULTIPLE LIVER TUMORS FORM, SOME OF WHICH ARE HEPATOCELLULAR CARCINOMAS. THE TUMORS IMMUNOSTAIN POSITIVELY FOR THE SAME PRENEOPLASTIC MARKERS AS THE PRENEOPLASTIC CELLS. SIMILAR CELLS ARE IDENTIFIED IN HUMAN CIRRHOSIS AND HEPATOCELLULAR CARCINOMA INDICATING THE RELEVANCE OF THE DRUG MODEL DESCRIBED HERE TO THE PRENEOPLASTIC CHANGES ASSOCIATED WITH HUMAN CHRONIC HEPATITIS AND HEPATOCELLULAR CARCINOMA. 2011 2 6272 31 THE ORIGIN AND PATHOGENESIS OF ENDOMETRIOSIS. RECENT MOLECULAR GENETIC FINDINGS ON ENDOMETRIOSIS AND NORMAL ENDOMETRIUM SUGGEST A MODIFIED MODEL IN WHICH CIRCULATING EPITHELIAL PROGENITOR OR STEM CELLS INTENDED TO REGENERATE UTERINE ENDOMETRIUM AFTER MENSTRUATION MAY BECOME OVERREACTIVE AND TRAPPED OUTSIDE THE UTERUS. THESE TRAPPED EPITHELIUM-COMMITTED PROGENITOR CELLS FORM NASCENT GLANDS THROUGH CLONAL EXPANSION AND RECRUIT POLYCLONAL STROMAL CELLS, LEADING TO THE ESTABLISHMENT OF DEEP INFILTRATING ENDOMETRIOSIS. ONCE FORMED, THE ECTOPIC TISSUE BECOMES SUBJECT TO IMMUNE SURVEILLANCE, RESULTING IN CHRONIC INFLAMMATION. THE INFLAMMATORY RESPONSE ORCHESTRATED BY NUCLEAR FACTOR-KAPPAB SIGNALING IS EXACERBATED BY ABERRATIONS IN THE ESTROGEN RECEPTOR-BETA AND PROGESTERONE RECEPTOR PATHWAYS, WHICH ARE ALSO AFFECTED BY LOCAL INFLAMMATION, FORMING A DYSREGULATED INFLAMMATION-HORMONAL LOOP. GLANDULAR EPITHELIUM WITHIN ENDOMETRIOTIC TISSUE HARBORS CANCER-ASSOCIATED MUTATIONS THAT ARE FREQUENTLY DETECTED IN ENDOMETRIOSIS-RELATED OVARIAN CANCERS. IN THIS REVIEW, WE SUMMARIZE RECENT ADVANCES THAT HAVE ILLUMINATED THE ORIGIN AND PATHOGENESIS OF ENDOMETRIOSIS AND HAVE PROVIDED NEW AVENUES FOR RESEARCH THAT PROMISE TO IMPROVE THE EARLY DIAGNOSIS AND MANAGEMENT OF ENDOMETRIOSIS. 2020 3 6374 33 THE ROLE OF MITOCHONDRIA IN MYOCARDIAL DAMAGE CAUSED BY ENERGY METABOLISM DISORDERS: FROM MECHANISMS TO THERAPEUTICS. MYOCARDIAL DAMAGE IS THE MOST SERIOUS PATHOLOGICAL CONSEQUENCE OF CARDIOVASCULAR DISEASES AND AN IMPORTANT REASON FOR THEIR HIGH MORTALITY. IN RECENT YEARS, BECAUSE OF THE HIGH PREVALENCE OF SYSTEMIC ENERGY METABOLISM DISORDERS (E.G., OBESITY, DIABETES MELLITUS, AND METABOLIC SYNDROME), COMPLICATIONS OF MYOCARDIAL DAMAGE CAUSED BY THESE DISORDERS HAVE ATTRACTED WIDESPREAD ATTENTION. ENERGY METABOLISM DISORDERS ARE INDEPENDENT OF TRADITIONAL INJURY-RELATED RISK FACTORS, SUCH AS ISCHEMIA, HYPOXIA, TRAUMA, AND INFECTION. AN IMBALANCE OF MYOCARDIAL METABOLIC FLEXIBILITY AND MYOCARDIAL ENERGY DEPLETION ARE USUALLY THE INITIAL CHANGES OF MYOCARDIAL INJURY CAUSED BY ENERGY METABOLISM DISORDERS, AND ABNORMAL MORPHOLOGY AND FUNCTIONAL DESTRUCTION OF THE MITOCHONDRIA ARE THEIR IMPORTANT FEATURES. SPECIFICALLY, MITOCHONDRIA ARE THE CENTERS OF ENERGY METABOLISM, AND RECENT EVIDENCE HAS SHOWN THAT DECREASED MITOCHONDRIAL FUNCTION, CAUSED BY AN IMBALANCE IN MITOCHONDRIAL QUALITY CONTROL, MAY PLAY A KEY ROLE IN MYOCARDIAL INJURY CAUSED BY ENERGY METABOLISM DISORDERS. UNDER CHRONIC ENERGY STRESS, MITOCHONDRIA UNDERGO PATHOLOGICAL FISSION, WHILE MITOPHAGY, MITOCHONDRIAL FUSION, AND BIOGENESIS ARE INHIBITED, AND MITOCHONDRIAL PROTEIN BALANCE AND TRANSFER ARE DISTURBED, RESULTING IN THE ACCUMULATION OF NONFUNCTIONAL AND DAMAGED MITOCHONDRIA. CONSEQUENTLY, DAMAGED MITOCHONDRIA LEAD TO MYOCARDIAL ENERGY DEPLETION AND THE ACCUMULATION OF LARGE AMOUNTS OF REACTIVE OXYGEN SPECIES, FURTHER AGGRAVATING THE IMBALANCE IN MITOCHONDRIAL QUALITY CONTROL AND FORMING A VICIOUS CYCLE. IN ADDITION, IMPAIRED MITOCHONDRIA COORDINATE CALCIUM HOMEOSTASIS IMBALANCE, AND EPIGENETIC ALTERATIONS PARTICIPATE IN THE PATHOGENESIS OF MYOCARDIAL DAMAGE. THESE PATHOLOGICAL CHANGES INDUCE RAPID PROGRESSION OF MYOCARDIAL DAMAGE, EVENTUALLY LEADING TO HEART FAILURE OR SUDDEN CARDIAC DEATH. TO INTERVENE MORE SPECIFICALLY IN THE MYOCARDIAL DAMAGE CAUSED BY METABOLIC DISORDERS, WE NEED TO UNDERSTAND THE SPECIFIC ROLE OF MITOCHONDRIA IN THIS CONTEXT IN DETAIL. ACCORDINGLY, PROMISING THERAPEUTIC STRATEGIES HAVE BEEN PROPOSED. WE ALSO SUMMARIZE THE EXISTING THERAPEUTIC STRATEGIES TO PROVIDE A REFERENCE FOR CLINICAL TREATMENT AND DEVELOPING NEW THERAPIES. 2023 4 1257 32 CURRENT TRENDS IN EPIGENETIC, CELLULAR AND MOLECULAR PATHWAYS IN MANAGEMENT OF RHEUMATOID ARTHRITIS. RHEUMATOID ARTHRITIS IS A SYSTEMIC CHRONIC POLYARTICULAR AUTOIMMUNE DISORDER OF JOINTS AND JOINT MEMBRANE MAINLY AFFECTING FEET AND HANDS. THE PATHOLOGICAL MANIFESTATION OF THE DISEASE INCLUDES INFILTRATION OF IMMUNE CELLS, HYPERPLASIA OF THE LINING OF SYNOVIUM, FORMATION OF PANNUS AND BONE AND CARTILAGE DESTRUCTION. IF LEFT UNTREATED, THE APPEARANCE OF SMALL FOCAL NECROSIS, ADHESION OF GRANULATION, AND FORMATION OF FIBROUS TISSUE ON THE SURFACE OF ARTICULAR CARTILAGE IS NOTED. THE DISEASE PRIMARILY AFFECTS NEARLY 1% OF THE POPULATION GLOBALLY, WOMEN BEING MORE AFFECTED THAN MEN WITH A RATIO 2:1 AND CAN INITIATE REGARDLESS OF ANY AGE. THE SYNOVIAL FIBROBLAST IN RHEUMATOID ARTHRITIS INDIVIDUALS EXHIBITS AN AGGRESSIVE PHENOTYPE WHICH UPREGULATES THE MANIFESTATION OF PROTOONCOGENES, ADHESIVE COMPOUNDS, INFLAMMATORY CYTOKINES AND MATRIX-DETERIORATING ENZYMES. APART FROM THE INFLAMMATORY EFFECTS OF CYTOKINES, CHEMOKINES ARE ALSO NOTED TO INDUCE SWELLING AND PAIN IN ARTHRITIC INDIVIDUALS BY RESIDING IN SYNOVIAL MEMBRANE AND FORMING PANNUS. THE CURRENT TREATMENT OF RHEUMATOID ARTHRITIS INCLUDES TREATMENT WITH NON-STEROIDAL ANTI-INFLAMMATORY DRUGS, DISEASE-MODIFYING ANTIRHEUMATIC DRUGS, TREATMENT WITH BIOLOGICS SUCH AS INHIBITORS OF TNF-ALPHA, INTERLEUKINS, PLATELET ACTIVATING FACTOR, ETC. WHICH PROVIDES SIGNIFICANT RELIEF FROM SYMPTOMS AND AIDS IN MANAGEMENT OF THE DISEASE. THE CURRENT REVIEW HIGHLIGHTS THE PATHOGENESIS INVOLVED IN THE ONSET OF RHEUMATOID ARTHRITIS AND ALSO COVERS EPIGENETIC, CELLULAR AND MOLECULAR PARAMETERS ASSOCIATED WITH IT TO AID BETTER AND ADVANCED THERAPEUTIC APPROACHES FOR MANAGEMENT OF THE DEBILITATING DISEASE. 2023 5 6394 38 THE ROLE OF THE HOST-NEUTROPHIL BIOLOGY. NEUTROPHILIC POLYMORPHONUCLEAR LEUKOCYTES (NEUTROPHILS) ARE MYELOID CELLS PACKED WITH LYSOSOMAL GRANULES (HENCE ALSO CALLED GRANULOCYTES) THAT CONTAIN A FORMIDABLE ANTIMICROBIAL ARSENAL. THEY ARE TERMINALLY DIFFERENTIATED CELLS THAT PLAY A CRITICAL ROLE IN ACUTE AND CHRONIC INFLAMMATION, AS WELL AS IN THE RESOLUTION OF INFLAMMATION AND WOUND HEALING. NEUTROPHILS EXPRESS A DENSE ARRAY OF SURFACE RECEPTORS FOR MULTIPLE LIGANDS, RANGING FROM INTEGRINS TO SUPPORT THEIR EGRESS FROM BONE MARROW INTO THE CIRCULATION AND FROM THE CIRCULATION INTO TISSUES, TO CYTOKINE/CHEMOKINE RECEPTORS THAT DRIVE THEIR NAVIGATION TO THE SITE OF INFECTION OR TISSUE DAMAGE AND ALSO PRIME THEM FOR A SECOND STIMULUS, TO PATTERN RECOGNITION RECEPTORS AND IMMUNOGLOBULIN RECEPTORS TO FACILITATE THE DESTRUCTION AND REMOVAL OF INFECTIVE AGENTS OR DEBRIDEMENT OF DAMAGED TISSUES. WHEN AFFERENT NEUTROPHIL SIGNALS ARE PROPORTIONATE AND COORDINATED THEY WILL PHAGOCYTOSE OPSONIZED AND UNOPSONIZED BACTERIA, ACTIVATING THE NICOTINAMIDE ADENINE DINUCLEOTIDE PHOSPHATE OXIDASE (RESPIRATORY BURST) TO GENERATE REACTIVE OXYGEN SPECIES, WHICH AUGMENT THE PROTEOLYTIC DESTRUCTION OF MICROBES SECURED WITHIN THE PHAGOSOME. A HIGHLY ORCHESTRATED PROCESS OF APOPTOSIS FOLLOWS, FORMING MEMBRANE-BOUND SUBSTRUCTURES THAT ARE REMOVED BY MACROPHAGES. NEUTROPHILS ARE CAPABLE OF VARIOUS OTHER FORMS OF PROGRAMMED CELL DEATH, SUCH AS NETOSIS AND PYROPTOTIC CELL DEATH, AS WELL AS NONPROGRAMMED CELL DEATH BY NECROSIS. IN RECENT YEARS, RESEARCH HAS REVEALED THAT NEUTROPHILS ARE CAPABLE OF FAR MORE SUBTLE CELL-CELL INTERACTIONS THAN PREVIOUSLY THOUGHT POSSIBLE. THIS INCLUDES SYNTHESIS OF VARIOUS INFLAMMATORY MEDIATORS AND ALSO MYELOID CELL TRAINING WITHIN BONE MARROW, WHERE EPIGENETIC AND METABOLIC SIGNALS ASSOCIATED WITH RETURNING NEUTROPHILS THAT UNDERGO REVERSE EGRESS FROM TISSUES INTO THE VASCULATURE AND BACK TO BONE MARROW PROGRAM A HYPERREACTIVE SUBSET OF NEUTROPHILS DURING MYELOPOIESIS THAT ARE CAPABLE OF HYPERSENSITIVE REACTIONS TO MICROBIAL AGGRESSORS. THESE CHARACTERISTICS ARE EVIDENT IN VARIOUS NEUTROPHIL SUBSETS/SUBPOPULATIONS, CREATING BROAD HETEROGENEITY IN THE BEHAVIOR AND BIOLOGICAL REPERTOIRE OF THESE SEEMINGLY SCHIZOPHRENIC IMMUNE CELLS. MOREOVER, NEUTROPHILS ARE CRITICAL EFFECTOR CELLS OF ADAPTIVE AND INNATE IMMUNITY, BINDING TO OPSONIZED BACTERIA AND DESTROYING THEM BY EXTRACELLULAR AND INTRACELLULAR METHODS. THE FORMER CREATES SUBSTANTIAL COLLATERAL HOST TISSUE DAMAGE, AS THEY ARE LESS SPECIFIC THAN T-CYTOTOXIC CELL-KILLING MECHANISMS, AND IN CONDITIONS SUCH AS PERI-IMPLANTITIS, WHERE PLASMA CELLS AND NEUTROPHILS DOMINATE THE IMMUNE INFILTRATE, BONE AND TISSUE DESTRUCTION ARE RAPID AND APPEAR RELENTLESS. FINALLY, THE ROLE OF NEUTROPHILS AS CONDUITS FOR PERIODONTAL-SYSTEMIC DISEASE CONNECTIONS AND FOR OXIDATIVE DAMAGE TO ACT AS A CAUSAL LINK BETWEEN THE TWO HAS ONLY RECENTLY BEEN REALIZED. IN THIS CHAPTER, WE ATTEMPT TO EXPAND ON THESE ISSUES, EMPHASIZING THE CONTRIBUTIONS OF EUROPEAN SCIENTISTS THROUGHOUT A DETAILED APPRAISAL OF THE BENEFITS AND SIDE EFFECTS OF NEUTROPHILIC INFLAMMATION AND IMMUNE FUNCTION. 2023 6 4151 30 MECHANISTIC INSIGHTS INTO GLUCOSE INDUCED VASCULAR EPIGENETIC REPROGRAMMING IN TYPE 2 DIABETES. ENDOTHELIAL CELLS LINING THE VESSEL WALL REGULATE THROMBOSIS, INFLAMMATION, ANGIOGENESIS AND BALANCE BETWEEN VASOCONSTRICTION AND VASODILATORY FUNCTIONS. SUBJECTS WITH TYPE 2 DIABETES (T2D) ACCRUE A MULTITUDE OF VASCULOPATHIES CAUSING HIGH MORBIDITY AND MORTALITY ACROSS THE GLOBE. HIGH GLUCOSE AND ITS MODIFIED PRODUCTS SUCH AS ADVANCED GLYCATION END PRODUCTS LEAD TO A BIDIRECTIONAL ACTIVATION OF INFLAMMATORY AND EPIGENETIC MACHINERY IN ENDOTHELIAL CELLS RESULTING IN A STATE OF CHRONIC INFLAMMATORY MILIEU AND EVENTUALLY INTO VASCULAR COMPLICATIONS. CLINICAL AND EXPERIMENTAL STUDIES HAVE SHOWN THAT DESPITE THE THERAPEUTIC NORMALIZATION OF GLUCOSE LEVELS, SUBJECTS WITH T2D OVERT TO VASCULAR COMPLICATIONS THROUGH A PROCESS OF METABOLIC MEMORY WHICH IS ASSOCIATED WITH SIGNIFICANT EPIGENETIC REPROGRAMMING IN ENDOTHELIAL CELLS. IN NORMAL PHYSIOLOGICAL CONDITIONS, VASCULAR ENDOTHELIAL CELLS DISPLAY A QUIESCENT STATE AND ONLY IN RESPONSE TO EITHER PHYSIOLOGICAL OR PATHOLOGICAL RESPONSE, ENDOTHELIAL CELLS UNDERGO PROLIFERATION. DURING THE PATHOGENESIS OF T2D, DNA METHYLATION, HISTONE MARKS AND NON-CODING RNAS FORMING THE EPIGENETIC LANDSCAPE ARE DYSREGULATED AND ACTIVATE QUIESCENT ENDOTHELIAL CELLS TO SWITCH ON A DIVERSE SET OF MOLECULAR ACTIVITIES AND LEAD TO ENDOTHELIAL DYSFUNCTION. IN THE PRESENT REVIEW, WE PROVIDE A COMPREHENSIVE OVERVIEW OF HOW HYPERGLYCEMIA IN T2D REPROGRAMS ENDOTHELIAL EPIGENOME AND LEAD TO FUNCTIONAL CONSEQUENCES IN THE PATHOGENESIS OF VASCULAR COMPLICATIONS. FURTHER, WE CATALOGUE AND DISCUSS EPI-DRUGS THAT MAY AMELIORATE ENDOTHELIAL FUNCTIONS DURING T2D. 2022 7 676 30 BRAIN AGING: A IANUS-FACED PLAYER BETWEEN HEALTH AND NEURODEGENERATION. NEURODEGENERATIVE DISEASES ARE INCURABLE DEBILITATING DISORDERS CHARACTERIZED BY STRUCTURAL AND FUNCTIONAL NEURONAL LOSS. APPROXIMATELY 30 MILLION PEOPLE ARE AFFECTED WORLDWIDE, AND THIS NUMBER IS PREDICTED TO REACH MORE THAN 150 MILLION BY 2050. NEURODEGENERATIVE DISORDERS INCLUDE ALZHEIMER'S, PARKINSON'S, AND PRION DISEASES AMONG OTHERS. THESE DISORDERS ARE CHARACTERIZED BY THE ACCUMULATION OF AGGREGATING PROTEINS FORMING AMYLOID, RESPONSIBLE FOR THE DISEASE-ASSOCIATED PATHOLOGICAL LESIONS. THE AGGREGATION OF AMYLOIDOGENIC PROTEINS CAN RESULT EITHER IN GAINING OF TOXIC FUNCTIONS, DERIVED FROM THE DAMAGE PROVOKED BY THESE DEPOSITS IN AFFECTED TISSUE, OR IN A LOSS OF FUNCTIONS, DUE TO THE SEQUESTRATION AND THE CONSEQUENT INABILITY OF THE AGGREGATING PROTEIN TO ENSURE ITS PHYSIOLOGICAL ROLE. WHILE IT IS WIDELY ACCEPTED THAT AGING REPRESENTS THE MAIN RISK FACTOR FOR NEURODEGENERATION, THERE IS STILL NO CLEAR CUT-OFF LINE BETWEEN THE TWO CONDITIONS. INDEED, MANY OF THE PATHWAYS THAT ARE COMMONLY ALTERED IN NEURODEGENERATION-MISFOLDED PROTEIN ACCUMULATION, CHRONIC INFLAMMATION, MITOCHONDRIAL DYSFUNCTION, IMPAIRED IRON HOMEOSTASIS, EPIGENETIC MODIFICATIONS-HAVE BEEN OFTEN CORRELATED ALSO WITH HEALTHY AGING. THIS OVERLAP COULD BE EXPLAINED BY THE FACT THAT THE CONTINUOUS ACCUMULATION OF CELLULAR DAMAGES, TOGETHER WITH A PROGRESSIVE DECLINE IN METABOLIC EFFICIENCY DURING AGING, MAKES THE NEURONS MORE VULNERABLE TO TOXIC INJURIES. WHEN A GIVEN THRESHOLD IS EXCEEDED, ALL THESE ALTERATIONS MIGHT GIVE RISE TO PATHOLOGICAL PHENOTYPES THAT ULTIMATELY LEAD TO NEURODEGENERATION. 2020 8 2350 30 EPIGENETIC REGULATION OF NEUROINFLAMMATION IN PARKINSON'S DISEASE. NEUROINFLAMMATION IS ONE OF THE MOST SIGNIFICANT FACTORS INVOLVED IN THE INITIATION AND PROGRESSION OF PARKINSON'S DISEASE. PD IS A NEURODEGENERATIVE DISORDER WITH A MOTOR DISABILITY LINKED WITH VARIOUS COMPLEX AND DIVERSIFIED RISK FACTORS. THESE FACTORS TRIGGER MYRIADS OF CELLULAR AND MOLECULAR PROCESSES, SUCH AS MISFOLDING DEFECTIVE PROTEINS, OXIDATIVE STRESS, MITOCHONDRIAL DYSFUNCTION, AND NEUROTOXIC SUBSTANCES THAT INDUCE SELECTIVE NEURODEGENERATION OF DOPAMINE NEURONS. THIS NEURONAL DAMAGE ACTIVATES THE NEURONAL IMMUNE SYSTEM, INCLUDING GLIAL CELLS AND INFLAMMATORY CYTOKINES, TO TRIGGER NEUROINFLAMMATION. THE TRANSITION OF ACUTE TO CHRONIC NEUROINFLAMMATION ENHANCES THE SUSCEPTIBILITY OF INFLAMMATION-INDUCED DOPAMINERGIC NEURON DAMAGE, FORMING A VICIOUS CYCLE AND PROMPTING AN INDIVIDUAL TO PD DEVELOPMENT. EPIGENETIC MECHANISMS RECENTLY HAVE BEEN AT THE FOREFRONT OF THE REGULATION OF NEUROINFLAMMATORY FACTORS IN PD, PROPOSING A NEW DAWN FOR BREAKING THIS VICIOUS CYCLE. THIS REVIEW EXAMINED THE CORE EPIGENETIC MECHANISMS INVOLVED IN THE ACTIVATION AND PHENOTYPIC TRANSFORMATION OF GLIAL CELLS MEDIATED NEUROINFLAMMATION IN PD. WE FOUND THAT EPIGENETIC MECHANISMS DO NOT WORK INDEPENDENTLY, DESPITE BEING COORDINATED WITH EACH OTHER TO ACTIVATE NEUROINFLAMMATORY PATHWAYS. IN THIS REGARD, WE ATTEMPTED TO FIND THE SYNERGIC CORRELATION AND CONTRIBUTION OF THESE EPIGENETIC MODIFICATIONS WITH VARIOUS NEUROINFLAMMATORY PATHWAYS TO BROADEN THE CANVAS OF UNDERLYING PATHOLOGICAL MECHANISMS INVOLVED IN PD DEVELOPMENT. MOREOVER, THIS STUDY HIGHLIGHTED THE DUAL CHARACTERISTICS (NEUROPROTECTIVE/NEUROTOXIC) OF THESE EPIGENETIC MARKS, WHICH MAY COUNTERACT PD PATHOGENESIS AND MAKE THEM POTENTIAL CANDIDATES FOR DEVISING FUTURE PD DIAGNOSIS AND TREATMENT. 2021 9 6457 45 TIC DISORDERS: WHEN HABIT FORMING NEURAL SYSTEMS FORM HABITS OF THEIR OWN? TOURETTE SYNDROME (TS), OBSESSIVE-COMPULSIVE DISORDER (OCD) AND RELATED CONDITIONS ARE PREVALENT DISORDERS AFFECTING AS MANY AS 0.3-3% OF THE POPULATION. THEY ARE FREQUENTLY CHRONIC AND CAN BE ASSOCIATED WITH MARKED IMPAIRMENT AND DISABILITY. ALTHOUGH CLINICAL CARE HAS IMPROVED OVER THE PAST DECADE, A SIGNIFICANT NUMBER OF PATIENTS FAIL TO RESPOND ADEQUATELY OR EXPERIENCE INTOLERABLE SIDE EFFECTS. THE ETIOLOGY OF THESE DISORDERS IS UNKNOWN. COMPELLING EVIDENCE SUGGESTS THAT THE VULNERABILITY TO DEVELOP TS AND OCD IS MEDIATED BY BOTH GENETIC AND ENVIRONMENTAL FACTORS, AND THAT NEURAL SYSTEMS LOCATED IN THE BASAL GANGLIA AND FUNCTIONALLY RELATED BRAIN STRUCTURES ARE INVOLVED IN THEIR PATHOGENESIS. BASED ON EXPLICIT MODELS OF PATHOGENESIS FOR TS AND OCD AND BUILDING ON WORK ACCOMPLISHED OVER THE PAST TWO DECADES, AN ARRAY OF CLINICAL, NEUROPSYCHOLOGICAL, GENETIC, NEUROIMAGING, EPIDEMIOLOGICAL NEUROBIOLOGICAL, AND TREATMENT STUDIES HAVE BEEN COMPLETED OR ARE UNDERWAY AT THE CHILD STUDY CENTER AT YALE UNIVERSITY. A MULTIDISCIPLINARY TEAM OF INVESTIGATORS HAS JOINED FORCES TO TEST SPECIFIC HYPOTHESES THROUGH THE INTEGRATION AND TRANSLATION OF BASIC AND CLINICAL NEUROSCIENCE RESEARCH. ALL SUBJECTS HAVE BEEN STUDIED USING IDENTICAL CLINICAL, NEUROPSYCHOLOGICAL, GENETIC, NEUROBIOLOGICAL, AND PHARMACOLOGICAL TECHNIQUES. CURRENT CONCEPTUALIZATIONS OF TS HAVE BEEN SHAPED BY ADVANCES IN CLINICAL PHENOMENOLOGY, GENETICS, SYSTEMS NEUROSCIENCE AND THE EMERGING UNDERSTANDING OF THE ROLE OF THE BASAL GANGLIA IN IMPLICIT LEARNING AND HABIT FORMATION, NEUROIMMUNOLOGY AND PSYCHOPHARMACOLOGY. AN APPRECIATION OF THE PREMONITORY URGES THAT PRECEDE TICS AND TEMPORAL DYNAMICS OF TICS HAVE PROVIDED USEFUL VIEWPOINTS FROM WHICH TO REGARD THE NATURAL HISTORY OF TS. WHILE THE LONG-TERM OUTCOME OF TS CAN BE RELATIVELY BENIGN, THE PRESENCE OF COMORBID CONDITIONS SUCH AS ATTENTION DEFICIT/HYPERACTIVITY DISORDER (ADHD), OCD OR A MAJOR AFFECTIVE DISORDER CAN HAVE LASTING UNTOWARD CONSEQUENCES. THE IDENTIFICATION OF SUSCEPTIBILITY GENES IN TS WILL DOUBTLESS POINT IN NEW THERAPEUTIC DIRECTIONS FOR TREATMENT, AS WILL THE CHARACTERIZATION OF THE PUTATIVE AUTOIMMUNE MECHANISMS ACTIVE IN SUBGROUP OF PATIENTS. CONTINUED SUCCESS IN FUNCTIONAL IN VIVO NEUROIMAGING STUDIES WILL LEAD TO THE TARGETING OF SPECIFIC BRAIN CIRCUITS FOR MORE INTENSIVE STUDY. ALTHOUGH IDEAL ANTI-TIC THERAPIES ARE NOT AVAILABLE, RECENTLY COMPLETED CLINICAL TRIALS WITH ALPHA-ADRENERGIC AGENTS AND ATYPICAL NEUROLEPTICS ARE ENCOURAGING. GIVEN THESE DEVELOPMENTS, TS CAN BE CONSIDERED A MODEL DISORDER TO STUDY THE DYNAMIC INTERPLAY OF GENETIC VULNERABILITIES, EPIGENETIC EVENTS, AND NEUROBIOLOGICAL SYSTEMS ACTIVE DURING EARLY BRAIN DEVELOPMENT. IT IS LIKELY THAT THE RESEARCH PARADIGMS UTILIZED IN THESE STUDIES AND MANY OF THE EMPIRICAL FINDINGS RESULTING FROM THEM, WILL BE RELEVANT TO OTHER DISORDERS OF CHILDHOOD ONSET AND TO OUR UNDERSTANDING OF NORMAL DEVELOPMENT. 2001 10 3934 56 LIVER TUMOR INDUCTION. THE SIGNIFICANCE OF THE DEVELOPMENT OF NODULAR LIVER LESIONS IN RODENTS FOLLOWING THE ADMINISTRATION OF TEST AGENTS RAISES SEVERAL QUESTIONS WHICH COULD BE PLACED IN ONE OF TWO GENERAL CATEGORIES: DIAGNOSTIC AND INTERPRETATIONAL. FROM A DIAGNOSTIC POINT OF VIEW, THE PROPER CLASSIFICATION OF LIVER TUMORS INTO A BENIGN AND MALIGNANT CATEGORY HAS TO BE BASED ON THE DIRECT CORRELATION BETWEEN THE MORPHOLOGY AND THE BIOLOGIC BEHAVIOR OF THE LESIONS. THEREFORE, EXTREME CARE SHOULD BE TAKEN TO SEPARATE THE MALIGNANT TUMORS FROM THE BENIGN AND THE BENIGN NEOPLASIA FROM THE HYPERPLASIA. THE SUBSTITUTION OF THE TERM "NEOPLASTIC NODULE" FOR HYPERPLASTIC NODULE IN RATS IS MISLEADING. MOST OF THESE NODULES, WHEN INDUCED UNDER SPECIAL EXPERIMENTAL CONDITIONS, MAY REGRESS OR REMODEL AND THUS THEY ARE NOT NEOPLASTIC IN NATURE. CHRONIC CARCINOGENICITY BIOASSAYS SHOULD INCLUDE "STOP" TYPE OF TREATMENT LEAVING ENOUGH OF THE OBSERVATIONAL TIME TO ESTABLISH THE FATE OF INDUCED NODULAR LESIONS. THE INDUCTION OF HISTOCHEMICALLY CHANGED FOCI CAN SERVE ONLY AS AN INDICATION OF POTENTIAL HEPATOCARCINOGENICITY AND SHOULD NOT BE EQUATED WITH THE INDUCTION OF BONA FIDE CANCER. THE BIOLOGIC INTERPRETATION OF NODULAR LIVER LESIONS, ESPECIALLY IN MICE, NEEDS FURTHER SCRUTINY BECAUSE THESE LESIONS HAVE A TENDENCY TO DEVELOP SPONTANEOUSLY WITH HIGH INCIDENCE IN SOME STRAINS. THIS CHARACTERISTIC THEN RAISES THE QUESTION AS TO THE MECHANISM BY WHICH VARIOUS AGENTS AUGMENT AND/OR ACCELERATE THE DEVELOPMENT OF SUCH TUMORS. IS THIS ACTION PRIMARILY PROMOTING OR INITIATING IN NATURE OR DOES IT REPRESENT THE INDUCTION OF TUMORS DE NOVO? THE ANSWER TO THIS DILEMMA MAY HAVE A DECISIVE BEARING ON CARCINOGENIC RISK ASSESSMENT AND THE TYPE OF REGULATORY ACTION, SINCE THE PROMOTING AGENTS POSSESS A THRESHOLD EFFECT AND THE PROMOTED CHANGES MAY REGRESS FOLLOWING WITHDRAWAL OF TREATMENT. THE INTERPRETATION OF HEPATOCARCINOGENESIS IS FURTHER COMPLICATED BY THE FACT THAT SEVERAL FACTORS, SUCH AS SEX HORMONAL ENVIRONMENT, INCREASED MITOTIC ACTIVITY FOLLOWING AN EXCESSIVE LOSS OF PARENCHYMAL CELLS, DEGREE OF CALORIC INTAKE, ENZYMATIC COMPLEMENT, AND ANIMALS' AGE AT THE TIME OF THE EXPOSURE TO A TEST AGENT, MAY INFLUENCE THE OUTCOME OF LIVER TUMOR DEVELOPMENT BY MODULATING "INITIATION" AND/OR "PROMOTION" OF CARCINOGENESIS. BROAD FLUCTUATION IN THE HISTORIC INCIDENCE OF LIVER TUMORS FURTHER COMPOUNDS THE COMPLEXITY OF THE PROPER BIOASSAY INTERPRETATION. THE SPECIFICALLY DESIGNED EXPERIMENTS MAY HAVE THE OBJECTIVE TO EXPLORE PREDOMINANTLY THE INITIATING OR PROMOTING EFFECTS OF THE AGENT. SUCH PROTOCOLS SHOULD BE USED WHENEVER NECESSARY TO DIFFERENTIATE BETWEEN THESE TWO MECHANISMS OF ACTION. IN THE CAUCASIANS, THE "SPONTANEOUS" DEVELOPMENT OF THE PRIMARY HEPATOCELLULAR TUMORS IS RARE. THE MAJORITY OF THESE TUMORS ARE MALIGNANT AND RAPIDLY FATAL. ACCORDING TO SOME HUMAN PATHOLOGISTS, THE BENIGN VARIETY OF LIVER TUMORS IS RARE AND IT DOES NOT REPRESENT NECESSARILY A PREMALIGNANT STAGE IN TUMOR DEVELOPMENT. CARCINOMA OF THE LIVER MAY OCCUR IN INFANCY, ESPECIALLY IN MALES BEFORE THE AGE OF 2 YEARS. THIS SUGGESTS A GENETIC CAUSATION OR CARCINOGENIC EXPOSURE IN UTERO. ONE OF THE GEOGRAPHIC FACTORS WHICH SIGNIFICANTLY ENHANCES THE INCIDENCE OF HEPATOCELLULAR CARCINOMA IN HUMANS IS EXPOSURE TO AFLATOXIN B(1) WHICH IS APPARENTLY POTENTIATED BY CONCURRENT LIVER CIRRHOSIS. BECAUSE MANY MORE AGENTS HAVE BEEN FOUND TO BE HEPATOCARCINOGENIC IN MICE AND RATS THAN IN MEN, A QUESTION ARISES AS TO THE DIRECT RELEVANCE OF RODENT STUDIES TO HUMANS. A BALANCED ASSESSMENT OF THE CARCINOGENICITY OF THE AGENT COULD ONLY BE REACHED IN CONSIDERING BOTH THE PHARMACOKINETICS AND THE DEVELOPMENT OF MALIGNANT NEOPLASIA IN OTHER ORGANS. IN THE CASE OF POSITIVE CARCINOGENICITY ASSESSMENT, THE OUTCOME OF THE MUTAGENICITY BIOASSAYS CAN SUGGEST GENIC (GENOTOXIC) OR PARAGENIC (EPIGENETIC) MODE OF ACTION IN MAMMALIAN SYSTEMS. 1982 11 3466 28 HYPOXIA AS A KEY PLAYER IN THE AKI-TO-CKD TRANSITION. RECENT CLINICAL AND ANIMAL STUDIES HAVE SHOWN THAT ACUTE KIDNEY INJURY (AKI), EVEN IF FOLLOWED BY COMPLETE RECOVERY OF RENAL FUNCTION, CAN EVENTUALLY RESULT IN CHRONIC KIDNEY DISEASE (CKD). RENAL HYPOXIA IS EMERGING AS A KEY PLAYER IN THE PATHOPHYSIOLOGY OF THE AKI-TO-CKD TRANSITION. CAPILLARY RAREFACTION AFTER AKI EPISODES INDUCES RENAL HYPOXIA, WHICH CAN IN TURN PROFOUNDLY AFFECT TUBULAR EPITHELIAL CELLS, (MYO)FIBROBLASTS, AND INFLAMMATORY CELLS, CULMINATING IN TUBULOINTERSTITIAL FIBROSIS, I.E., PROGRESSION TO CKD. DAMAGED TUBULAR EPITHELIAL CELLS THAT FAIL TO REDIFFERENTIATE MIGHT SUPPLY A DECREASED AMOUNT OF VASCULAR ENDOTHELIAL GROWTH FACTOR AND CONTRIBUTE TO CAPILLARY RAREFACTION, THUS AGGRAVATING HYPOXIA AND FORMING A VICIOUS CYCLE. MOUNTING EVIDENCE ALSO SHOWS THAT EPIGENETIC CHANGES ARE CLOSELY RELATED TO RENAL HYPOXIA IN THE PATHOPHYSIOLOGY OF CKD PROGRESSION. ANIMAL EXPERIMENTS SUGGEST THAT TARGETING HYPOXIA IS A PROMISING STRATEGY TO BLOCK THE TRANSITION FROM AKI TO CKD. HOWEVER, THE PRECISE MECHANISMS BY WHICH HYPOXIA INDUCES THE AKI-TO-CKD TRANSITION AND BY WHICH HYPOXIA-INDUCIBLE FACTOR ACTIVATION CAN EXERT A PROTECTIVE EFFECT IN THIS CONTEXT SHOULD BE CLARIFIED IN FURTHER STUDIES. 2014 12 5816 32 STRESS AND STEM CELLS. THE UNIQUE PROPERTIES AND FUNCTIONS OF STEM CELLS MAKE THEM PARTICULARLY SUSCEPTIBLE TO STRESSES AND ALSO LEAD TO THEIR REGULATION BY STRESS. STEM CELL DIVISION MUST RESPOND TO THE DEMAND TO REPLENISH CELLS DURING NORMAL TISSUE TURNOVER AS WELL AS IN RESPONSE TO DAMAGE. OXIDATIVE STRESS, MECHANICAL STRESS, GROWTH FACTORS, AND CYTOKINES SIGNAL STEM CELL DIVISION AND DIFFERENTIATION. MANY OF THE CONSERVED PATHWAYS REGULATING STEM CELL SELF-RENEWAL AND DIFFERENTIATION ARE ALSO STRESS-RESPONSE PATHWAYS. THE LONG LIFE SPAN AND DIVISION POTENTIAL OF STEM CELLS CREATE A PROPENSITY FOR TRANSFORMATION (CANCER) AND SPECIFIC STRESS RESPONSES SUCH AS APOPTOSIS AND SENESCENCE ACT AS ANTITUMOR MECHANISMS. QUIESCENCE REGULATED BY CDK INHIBITORS AND A HYPOXIC NICHE REGULATED BY FOXO TRANSCRIPTION FACTOR FUNCTION TO REDUCE STRESS FOR SEVERAL TYPES OF STEM CELLS TO FACILITATE LONG-TERM MAINTENANCE. AGING IS A PARTICULARLY RELEVANT STRESS FOR STEM CELLS, BECAUSE REPEATED DEMANDS ON STEM CELL FUNCTION OVER THE LIFE SPAN CAN HAVE CUMULATIVE CELL-AUTONOMOUS EFFECTS INCLUDING EPIGENETIC DYSREGULATION, MUTATIONS, AND TELOMERE EROSION. IN ADDITION, AGING OF THE ORGANISM IMPAIRS FUNCTION OF THE STEM CELL NICHE AND SYSTEMIC SIGNALS, INCLUDING CHRONIC INFLAMMATION AND OXIDATIVE STRESS. 2012 13 799 30 CELLULAR SIGNALING AND POTENTIAL NEW TREATMENT TARGETS IN DIABETIC RETINOPATHY. DYSFUNCTION AND DEATH OF MICROVASCULAR CELLS AND IMBALANCE BETWEEN THE PRODUCTION AND THE DEGRADATION OF EXTRACELLULAR MATRIX (ECM) PROTEINS ARE A CHARACTERISTIC FEATURE OF DIABETIC RETINOPATHY (DR). GLUCOSE-INDUCED BIOCHEMICAL ALTERATIONS IN THE VASCULAR ENDOTHELIAL CELLS MAY ACTIVATE A CASCADE OF SIGNALING PATHWAYS LEADING TO INCREASED PRODUCTION OF ECM PROTEINS AND CELLULAR DYSFUNCTION/DEATH. CHRONIC DIABETES LEADS TO THE ACTIVATION OF A NUMBER OF SIGNALING PROTEINS INCLUDING PROTEIN KINASE C, PROTEIN KINASE B, AND MITOGEN-ACTIVATED PROTEIN KINASES. THESE SIGNALING CASCADES ARE ACTIVATED IN RESPONSE TO HYPERGLYCEMIA-INDUCED OXIDATIVE STRESS, POLYOL PATHWAY, AND ADVANCED GLYCATION END PRODUCT FORMATION AMONG OTHERS. THE ABERRANT SIGNALING PATHWAYS ULTIMATELY LEAD TO ACTIVATION OF TRANSCRIPTION FACTORS SUCH AS NUCLEAR FACTOR-KAPPAB AND ACTIVATING PROTEIN-1. THE ACTIVITY OF THESE TRANSCRIPTION FACTORS IS ALSO REGULATED BY EPIGENETIC MECHANISMS THROUGH TRANSCRIPTIONAL COACTIVATOR P300. THESE COMPLEX SIGNALING PATHWAYS MAY BE INVOLVED IN GLUCOSE-INDUCED ALTERATIONS OF ENDOTHELIAL CELL PHENOTYPE LEADING TO THE PRODUCTION OF INCREASED ECM PROTEINS AND VASOACTIVE EFFECTOR MOLECULES CAUSING FUNCTIONAL AND STRUCTURAL CHANGES IN THE MICROVASCULATURE. UNDERSTANDING OF SUCH MECHANISTIC PATHWAYS WILL HELP TO DEVELOP FUTURE ADJUVANT THERAPIES FOR DIABETIC RETINOPATHY. 2007 14 1451 30 DISALLOWED AND ALLOWED GENE EXPRESSION: TWO FACES OF MATURE ISLET BETA CELLS. GLUCOSE HOMEOSTASIS GREATLY DEPENDS ON THE MATCH BETWEEN FLUCTUATING INSULIN DEMANDS AND ADJUSTED RATES OF INSULIN SECRETION, WHICH IS THE FUNCTION OF PANCREATIC BETA CELLS. EMERGING EVIDENCE SUGGESTS THAT WHEN NEONATAL BETA CELLS MATURE, THEY ACQUIRE TWO FACES OF DIFFERENTIATED FUNCTION: AN EXPECTED "VISIBLE FACE" THAT DEPENDS ON SPECIFIC BETA CELL PROTEINS NEEDED FOR REGULATED INSULIN RELEASE, BUT ALSO A "HIDDEN FACE" THAT REPRESSES UBIQUITOUS PROTEINS TO PREVENT INAPPROPRIATE BETA CELL FUNCTION SUCH AS ELEVATED BASAL HORMONE SECRETION OR INSULIN RELEASE TRIGGERED BY EXERCISE. THIS REVIEW HIGHLIGHTS THIS NOVEL CONCEPT, AND WE FIRST PROPOSE THAT HIDDEN FACES MAY ALSO BE RELEVANT FOR OTHER SPECIALIZED TISSUE FUNCTIONS, SUCH AS KETOGENESIS IN THE LIVER. NEXT, WE DISCUSS THREE SCENARIOS IN WHICH ABERRANT GENE EXPRESSION CAUSES ABNORMAL GLUCOSE-INDUCED INSULIN RELEASE AND THE EPIGENETIC REGULATION OF THE HIDDEN FACE IN BETA CELLS. WE CONCLUDE WITH PERSPECTIVES FOR NEW RESEARCH, INCLUDING BETA CELL REPLACEMENT TO CURE DIABETES. 2016 15 737 46 CANCER STEM CELLS. THERE IS AN INCREASING EVIDENCE SUPPORTING THE CANCER STEM CELL HYPOTHESIS. NORMAL STEM CELLS IN THE ADULT ORGANISM ARE RESPONSIBLE FOR TISSUE RENEWAL AND REPAIR OF AGED OR DAMAGED TISSUE. A SUBSTANTIAL CHARACTERISTIC OF STEM CELLS IS THEIR ABILITY FOR SELF-RENEWAL WITHOUT LOSS OF PROLIFERATION CAPACITY WITH EACH CELL DIVISION. THE STEM CELLS ARE IMMORTAL, AND RATHER RESISTANT TO ACTION OF DRUGS. THEY ARE ABLE TO DIFFERENTIATE AND FORM SPECIFIC TYPES OF TISSUE DUE TO THE INFLUENCE OF MICROENVIRONMENTAL AND SOME OTHER FACTORS. STEM CELLS DIVIDE ASYMMETRICALLY PRODUCING TWO DAUGHTER CELLS -- ONE IS A NEW STEM CELL AND THE SECOND IS PROGENITOR CELL, WHICH HAS THE ABILITY FOR DIFFERENTIATION AND PROLIFERATION, BUT NOT THE CAPABILITY FOR SELF-RENEWAL. CANCER STEM CELLS ARE IN MANY ASPECTS SIMILAR TO THE STEM CELLS. IT HAS BEEN PROVEN THAT TUMOR CELLS ARE HETEROGENEOUS COMPRISING RARE TUMOR INITIATING CELLS AND ABUNDANT NON-TUMOR INITIATING CELLS. TUMOR INITIATING CELLS -- CANCER STEM CELLS HAVE THE ABILITY OF SELF-RENEWAL AND PROLIFERATION, ARE RESISTANT TO DRUGS, AND EXPRESS TYPICAL MARKERS OF STEM CELLS. IT IS NOT CLEAR WHETHER CANCER STEM CELLS ORIGINATE FROM NORMAL STEM CELLS IN CONSEQUENCE OF GENETIC AND EPIGENETIC CHANGES AND/OR BY REDIFFERENTIATION FROM SOMATIC TUMOR CELLS TO THE STEM-LIKE CELLS. PROBABLY BOTH MECHANISMS ARE INVOLVED IN THE ORIGIN OF CANCER STEM CELLS. DYSREGULATION OF STEM CELL SELF-RENEWAL IS A LIKELY REQUIREMENT FOR THE DEVELOPMENT OF CANCER. ISOLATION AND IDENTIFICATION OF CANCER STEM CELLS IN HUMAN TUMORS AND IN TUMOR CELL LINES HAS BEEN SUCCESSFUL. TO DATE, THE EXISTENCE OF CANCER STEM CELLS HAS BEEN PROVEN IN ACUTE AND CHRONIC MYELOID LEUKEMIA, IN BREAST CANCER, IN BRAIN TUMORS, IN LUNG CANCER AND GASTROINTESTINAL TUMORS. CANCER STEM CELL MODEL IS ALSO CONSISTENT WITH SOME CLINICAL OBSERVATIONS. ALTHOUGH STANDARD CHEMOTHERAPY KILLS MOST CELLS IN A TUMOR, CANCER STEM CELLS REMAIN VIABLE. DESPITE THE SMALL NUMBER OF SUCH CELLS, THEY MIGHT BE THE CAUSE OF TUMOR RECURRENCE, SOMETIMES MANY YEARS AFTER THE "SUCCESSFUL" TREATMENT OF PRIMARY TUMOR. GROWTH OF METASTASES IN DISTINCT AREAS OF BODY AND THEIR CELLULAR HETEROGENEITY MIGHT BE CONSEQUENCE OF CANCER STEM CELL DIFFERENTIATION AND/OR DEDIFFERENTIATION AND ASYMMETRIC DIVISION OF CANCER STEM CELLS. FURTHER CHARACTERIZATION OF CANCER STEM CELLS IS NEEDED IN ORDER TO FIND WAYS TO DESTROY THEM, WHICH MIGHT CONTRIBUTE SIGNIFICANTLY TO THE THERAPEUTIC MANAGEMENT OF MALIGNANT TUMORS. 2005 16 6621 35 UNDERSTANDING FIBROSIS IN SYSTEMIC SCLEROSIS: SHIFTING PARADIGMS, EMERGING OPPORTUNITIES. FIBROSIS IN MULTIPLE ORGANS IS A PROMINENT PATHOLOGICAL FINDING AND DISTINGUISHING HALLMARK OF SYSTEMIC SCLEROSIS (SSC). FINDINGS DURING THE PAST 5 YEARS HAVE CONTRIBUTED TO A MORE COMPLETE UNDERSTANDING OF THE COMPLEX CELLULAR AND MOLECULAR UNDERPINNING OF FIBROSIS IN SSC. FIBROBLASTS, THE PRINCIPAL EFFECTOR CELLS, ARE ACTIVATED IN THE PROFIBROTIC CELLULAR MILIEU BY CYTOKINES AND GROWTH FACTORS, DEVELOPMENTAL PATHWAYS, ENDOTHELIN 1 AND THROMBIN. INNATE IMMUNE SIGNALING VIA TOLL-LIKE RECEPTORS, MATRIX-GENERATED BIOMECHANICAL STRESS SIGNALING VIA INTEGRINS, HYPOXIA AND OXIDATIVE STRESS SEEM TO BE IMPLICATED IN PERPETUATING THE PROCESS. BEYOND CHRONIC FIBROBLAST ACTIVATION, FIBROSIS REPRESENTS A FAILURE TO TERMINATE TISSUE REPAIR, COUPLED WITH AN EXPANDED POPULATION OF MESENCHYMAL CELLS ORIGINATING FROM BONE MARROW AND TRANSDIFFERENTIATION OF EPITHELIAL CELLS, ENDOTHELIAL CELLS AND PERICYTES. IN ADDITION, STUDIES HAVE IDENTIFIED INTRINSIC ALTERATIONS IN SSC FIBROBLASTS RESULTING FROM EPIGENETIC CHANGES, AS WELL AS ALTERED MICRORNA EXPRESSION THAT MIGHT UNDERLIE THE CELL-AUTONOMOUS, PERSISTENT ACTIVATION PHENOTYPE OF THESE CELLS. PRECISE CHARACTERIZATION OF THE DEREGULATED EXTRACELLULAR AND INTRACELLULAR SIGNALING PATHWAYS, MEDIATORS AND CELLULAR DIFFERENTIATION PROGRAMS THAT CONTRIBUTE TO FIBROSIS IN SSC WILL FACILITATE THE DEVELOPMENT OF SELECTIVE, TARGETED THERAPEUTIC STRATEGIES. EFFECTIVE ANTIFIBROTIC THERAPY WILL ULTIMATELY INVOLVE NOVEL COMPOUNDS AND REPURPOSING OF DRUGS THAT ARE ALREADY APPROVED FOR OTHER INDICATIONS. 2011 17 6151 26 THE FIRE WITHIN: CELL-AUTONOMOUS MECHANISMS IN INFLAMMATION-DRIVEN CANCER. INFLAMMATORY CELLS ARE IMPORTANT FOR TUMOR INITIATION AND PROMOTION, PROVIDING CANCER CELLS WITH CYTOKINES THAT ENHANCE CELL PROLIFERATION AND SURVIVAL. ALTHOUGH MALIGNANT EPITHELIAL CELLS WERE TRADITIONALLY CONSIDERED TO BE ON THE RECEIVING END OF THESE MICROENVIRONMENTAL INTERACTIONS, RECENT STUDIES SHOW THAT EPITHELIAL CELLS CAN UNDERGO INFLAMMATORY REPROGRAMMING ON THEIR OWN. SUCH EPIGENETIC SWITCHES ARE OFTEN TRIGGERED BY CHRONIC TISSUE INJURY AND PLAY IMPORTANT ROLES IN TISSUE REPAIR. BY CONVERTING TERMINALLY DIFFERENTIATED CELLS THAT HARBOR EVEN A SINGLE ONCOGENIC MUTATION TO A LESS DIFFERENTIATED STATE WITH A HIGHER PROLIFERATIVE POTENTIAL, CELL-AUTONOMOUS INFLAMMATION IS AN IMPORTANT CONTRIBUTOR TO TUMOR INITIATION. 2019 18 3184 34 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 19 5282 32 PROMOTION OF HEPATOCARCINOGENESIS IN HUMANS AND ANIMAL MODELS. RISK ASSESSMENT BASED ON RODENT CARCINOGENICITY DATA DEPENDS ON THE ASSUMPTION OF SIMILARITY BETWEEN RODENTS AND HUMANS. WHILE THIS ASSUMPTION IS CONCEIVABLE IN THE CASE OF GENOTOXIC INITIATING CARCINOGENS, CONSIDERABLE SPECIES DIFFERENCES HAVE BEEN OBSERVED WITH NONGENOTOXIC TUMOR PROMOTERS. THIS HETEROGENEOUS GROUP OF AGENTS INCREASES THE PROBABILITY OF CANCER BY STIMULATING SELECTION AND CLONAL EXPANSION OF CELLS TRANSFORMED DURING TUMOR INITIATION. SINCE TUMOR PROMOTERS DIFFERENTIALLY AFFECT NORMAL TISSUE AND PRENEOPLASTIC CELL CLONES, THEIR ACTION CANNOT BE DISCUSSED WITHOUT KNOWLEDGE OF PERSISTENT GENOMIC AND EPIGENETIC ALTERATIONS OCCURRING DURING INITIATION AND FORMATION OF PRENEOPLASTIC CELLS. CHEMICAL CARCINOGENESIS, AND IN PARTICULAR, TUMOR PROMOTION, IS KNOWN TO BE TISSUE SPECIFIC. WE FOCUS ON HEPATOCARCINOGENESIS IN HUMANS AND IN ANIMAL MODELS AND EMPHASIZE TWO DIFFERENT MODES OF ACTION: (1) CHRONIC CYTOTOXICITY LEADING TO PROMOTION OF LIVER CARCINOGENESIS IN BOTH HUMANS AND ANIMAL MODELS; (2) SUSTAINED ACTIVATION OF ORPHAN RECEPTORS SUCH AS CAR, PPARALPHA AND AH RECEPTOR LEADING TO PROMOTION OF RODENT BUT PROBABLY NOT HUMAN HEPATOCARCINOGENESIS. FURTHER STUDIES ON THE DIFFERENT MODES OF ACTION MAY HELP TO AVOID OVERESTIMATION OF THE RISK OF LIVER TUMOR PROMOTION. 2008 20 835 40 CHEMICAL CARCINOGEN MECHANISMS OF ACTION AND IMPLICATIONS FOR TESTING METHODOLOGY. CHEMICAL CARCINOGENS ARE OF TWO DISTINCT TYPES, DNA-REACTIVE AND EPIGENETIC. TESTING METHODOLOGY CAN BE DIRECTED TOWARD DETECTING EFFECTS OF BOTH TYPES OF CARCINOGEN. CARCINOGENS OF THE DNA-REACTIVE TYPE ARE DEFINED BY THE FORMATION OF COVALENTLY BOUND DNA ADDUCTS. THESE CHEMICALS HAVE STRUCTURES THAT YIELD ELECTROPHILIC REACTANTS EITHER DIRECTLY OR AFTER BIOACTIVATION. THESE AGENTS CAUSE GENOMIC ALTERATION IN THE STRUCTURE OR FUNCTION OF DNA IN THE TARGET CELL. IN ADDITION, THESE COMPOUNDS CAN EXERT OTHER CELLULAR AND TISSUE EPIGENETIC EFFECTS, SUCH AS CELL PROLIFERATION AND GROWTH PROMOTION. CARCINOGENS OF THE EPIGENETIC (PARAGENETIC) TYPE, IN CONTRAST, DO NOT REACT WITH DNA, BUT RATHER DISPLAY CELLULAR EFFECTS SUCH AS NEOPLASM GROWTH PROMOTION, CYTOTOXICITY, INHIBITION OF TISSUE GROWTH REGULATION, PEROXISOME PROLIFERATION, ENDOCRINE MODIFICATION, IMMUNOSUPPRESSION AND/OR SUSTAINED TISSUE ISCHEMIA THAT CAN BE THE BASIS FOR INCREASES IN NEOPLASIA. THEIR CHEMICAL STRUCTURE IS SUCH THAT THEY DO NOT GIVE RISE TO A REACTIVE ELECTROPHILE. THE TESTING METHODOLOGIES TO IDENTIFY EITHER TYPE FOLLOW A DECISION POINT APPROACH DESIGNED TO IDENTIFY POTENTIAL CARCINOGENICITY AND YIELD MECHANISTIC INFORMATION ON THE PRODUCTION OF EFFECTS THAT UNDERLIE CARCINOGENICITY. IT HAS 5 STAGES FOCUSING ON THE CHEMICAL STRUCTURE, DNA-REACTIVITY, EPIGENETIC EFFECTS, LIMITED BIOASSAYS AND FINALLY THE APPLICATION OF THE ACCELERATED BIOASSAY (ABA). ABA REQUIRES 40 WEEKS AND APPLIES THE USE OF SENSITIVE MARKERS FOR INDUCTION OF NEOPLASIA IN COMPARISON TO POSITIVE CONTROL COMPOUNDS FOR IMPORTANT ORGANS IN HUMAN CARCINOGENESIS. IT ENABLES DATA ACQUISITION OF THE ENTIRE CARCINOGENIC PROCESS DIRECTED TOWARD DEVELOPING MECHANISTIC INFORMATION. THE ABA HAS THE POTENTIAL TO REPLACE THE CHRONIC BIOASSAY IN RODENTS IN SOME CIRCUMSTANCES AND CAN SERVE AS AN ALTERNATIVE TO A CHRONIC BIOASSAY IN A SECOND SPECIES. 1996