1 1257 142 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 2 3789 37 INTERLEUKIN 17 CONTRIBUTES TO THE CHRONICITY OF INFLAMMATORY DISEASES SUCH AS RHEUMATOID ARTHRITIS. RHEUMATOID ARTHRITIS (RA) IS A CHRONIC INFLAMMATORY DISEASE LEADING TO JOINT DESTRUCTION AND BONE RESORPTION. THE PROINFLAMMATORY CYTOKINE INTERLEUKIN 17 (IL-17), PRIMARILY PRODUCED BY TH17 CELLS, HAS BEEN SHOWN TO BE INVOLVED IN ALL STAGES OF THE DISEASE AND TO BE AN IMPORTANT CONTRIBUTOR OF RA CHRONICITY. THREE MAJOR PROCESSES DRIVE THE IL-17-MEDIATED CHRONICITY. SEVERAL EPIGENETIC EVENTS, ENHANCED IN RA PATIENTS, LEAD TO THE INCREASED PRODUCTION OF IL-17 BY TH17 CELLS. IL-17 THEN INDUCES THE PRODUCTION OF SEVERAL INFLAMMATORY MEDIATORS IN THE DISEASED SYNOVIUM, WHICH ARE FURTHER SYNERGISTICALLY ENHANCED VIA COMBINATIONS OF IL-17 WITH OTHER CYTOKINES. IL-17 ALSO PROMOTES THE SURVIVAL OF BOTH THE SYNOVIOCYTES AND INFLAMMATORY CELLS AND PROMOTES THE MATURATION OF THESE IMMUNE CELLS. THIS LEADS TO AN INCREASED NUMBER OF SYNOVIOCYTES AND INFLAMMATORY CELLS IN THE SYNOVIAL FLUID AND IN THE SYNOVIUM LEADING TO THE HYPERPLASIA AND EXACERBATED INFLAMMATION OBSERVED IN JOINTS OF RA PATIENTS. FURTHERMORE, THESE IL-17-DRIVEN EVENTS INITIATE SEVERAL FEEDBACK-LOOP MECHANISMS LEADING TO INCREASED EXPANSION OF TH17 CELLS AND THEREBY INCREASED PRODUCTION OF IL-17. IN THIS REVIEW, WE AIM TO DEPICT A COMPLETE PICTURE OF THE IL-17-DRIVEN VICIOUS CIRCLE LEADING TO RA CHRONICITY AND TO PINPOINT THE KEY ASPECTS THAT REQUIRE FURTHER EXPLORATION. 2014 3 3677 29 INFLAMMATION AND PYROPTOSIS MEDIATE MUSCLE EXPANSION IN AN INTERLEUKIN-1BETA (IL-1BETA)-DEPENDENT MANNER. MUSCLE INFLAMMATION IS OFTEN ASSOCIATED WITH ITS EXPANSION. BLADDER SMOOTH MUSCLE INFLAMMATION-INDUCED CELL DEATH IS ACCOMPANIED BY HYPERPLASIA AND HYPERTROPHY AS THE PRIMARY CAUSE FOR POOR BLADDER FUNCTION. IN MICE, DNA DAMAGE INITIATED BY CHEMOTHERAPEUTIC DRUG CYCLOPHOSPHAMIDE ACTIVATED CASPASE 1 THROUGH THE FORMATION OF THE NLRP3 COMPLEX RESULTING IN DETRUSOR HYPERPLASIA. A CYCLOPHOSPHAMIDE METABOLITE, ACROLEIN, CAUSED GLOBAL DNA METHYLATION AND ACCUMULATION OF DNA DAMAGE IN A MOUSE MODEL OF BLADDER INFLAMMATION AND IN CULTURED BLADDER MUSCLE CELLS. IN CORRELATION, GLOBAL DNA METHYLATION AND NLRP3 EXPRESSION WAS UP-REGULATED IN HUMAN CHRONIC BLADDER INFLAMMATORY TISSUES. THE EPIGENETIC SILENCING OF DNA DAMAGE REPAIR GENE, OGG1, COULD BE REVERSED BY THE USE OF DEMETHYLATING AGENTS. IN MICE, DEMETHYLATING AGENTS REVERSED CYCLOPHOSPHAMIDE-INDUCED BLADDER INFLAMMATION AND DETRUSOR EXPANSION. THE TRANSGENIC KNOCK-OUT OF OGG1 IN AS FEW AS 10% OF THE DETRUSOR CELLS TRIPLED THE PROLIFERATION OF THE REMAINING WILD TYPE COUNTERPARTS IN AN IN VITRO CO-CULTURE TITRATION EXPERIMENT. ANTAGONIZING IL-1BETA WITH ANAKINRA, A RHEUMATOID ARTHRITIS THERAPEUTIC, PREVENTED DETRUSOR PROLIFERATION IN CONDITIONED MEDIA EXPERIMENTS AS WELL AS IN A MOUSE MODEL OF BLADDER INFLAMMATION. RADIATION TREATMENT VALIDATED THE ROLE OF DNA DAMAGE IN THE NLRP3-ASSOCIATED CASPASE 1-MEDIATED IL-1BETA SECRETORY PHENOTYPE. A PROTEIN ARRAY ANALYSIS IDENTIFIED IGF1 TO BE DOWNSTREAM OF IL-1BETA SIGNALING. IL-1BETA-INDUCED DETRUSOR PROLIFERATION AND HYPERTROPHY COULD BE REVERSED WITH THE USE OF ANAKINRA AS WELL AS AN IGF1 NEUTRALIZING ANTIBODY. IL-1BETA ANTAGONISTS IN CURRENT CLINICAL PRACTICE CAN EXPLOIT THE REVEALED MECHANISM FOR DNA DAMAGE-MEDIATED MUSCULAR EXPANSION. 2015 4 2082 24 EPIGENETIC DOWNREGULATION OF SFRP4 CONTRIBUTES TO EPIDERMAL HYPERPLASIA IN PSORIASIS. PSORIASIS IS A CHRONIC RECURRENT INFLAMMATORY SKIN DISORDER CHARACTERIZED BY THE DYSREGULATED CROSS-TALK BETWEEN EPIDERMAL KERATINOCYTES AND IMMUNE CELLS, LEADING TO KERATINOCYTE HYPERPROLIFERATION. SEVERAL STUDIES DEMONSTRATED THAT WNT PATHWAY GENES WERE DIFFERENTIALLY EXPRESSED IN PSORIATIC PLAQUES AND LIKELY WERE INVOLVED IN THE PATHOPHYSIOLOGY OF DISEASE. HOWEVER, THE MOLECULAR MECHANISMS UNDERLYING WNT SIGNALING REGULATION IN EPIDERMAL HYPERPLASIA IN PSORIASIS REMAIN LARGELY UNKNOWN. WE REPORT THAT THE EXPRESSION OF SECRETED FRIZZLED-RELATED PROTEIN (SFRP) 4, A NEGATIVE REGULATOR OF THE WNT SIGNALING PATHWAY, WAS DIMINISHED IN LESIONAL SKIN OF MOUSE MODELS AND PATIENTS WITH PSORIASIS. SFRP4 DIRECTLY INHIBITED EXCESSIVE KERATINOCYTE PROLIFERATION EVOKED BY PROINFLAMMATORY CYTOKINES IN VITRO. PHARMACOLOGICAL INHIBITION OF WNT SIGNALING OR INTRADERMAL INJECTION OF SFRP4 DECREASED THE SEVERITY OF THE PSORIASIFORM SKIN PHENOTYPE IN VIVO, INCLUDING DECREASED ACANTHOSIS AND REDUCED LEUKOCYTE INFILTRATION. MECHANISTICALLY, WE IDENTIFIED THAT ABERRANT PROMOTER METHYLATION RESULTED IN EPIGENETIC DOWNREGULATION OF SFRP4 IN INFLAMED SKIN OF PATIENTS WITH PSORIASIS AND IN THE IL-23-INDUCED MOUSE MODEL. OUR FINDINGS SUGGEST THAT THIS EPIGENETIC EVENT IS CRITICALLY INVOLVED IN THE PATHOGENESIS OF PSORIASIS, AND THE DOWNREGULATION OF SFRP4 BY CPG ISLAND METHYLATION IS ONE POSSIBLE MECHANISM CONTRIBUTING TO THE HYPERPLASIA OF EPIDERMIS IN THE DISEASE. 2015 5 6110 29 THE EPIGENETIC ALTERATION OF SYNOVIAL CELL GENE EXPRESSION IN RHEUMATOID ARTHRITIS AND THE ROLES OF NUCLEAR FACTOR KAPPAB AND NOTCH SIGNALING PATHWAYS. RHEUMATOID ARTHRITIS (RA) IS A COMPLEX PROCESS OF CHRONIC AND PROGRESSIVE INFLAMMATION ASSOCIATED WITH ACTIVATION OF NUMEROUS SIGNALING MOLECULES AND TRANSCRIPTION FACTORS AND HYPERPROLIFERATION OF SYNOVIOCYTES OF THE AFFECTED JOINTS, ALTHOUGH THE GREATER PART OF ITS PATHOPHYSIOLOGICAL PROCESS IS EXPLAINED BY ACTIVATION OF NUCLEAR FACTOR KAPPAB (NF-KAPPAB). FOR EXAMPLE, THE SELF-PERPETUATING NATURE OF THE RHEUMATOID INFLAMMATION IS ASCRIBABLE TO OVEREXPRESSION OF THE PROINFLAMMATORY CYTOKINES TUMOR NECROSIS FACTOR ALPHA AND INTERLEUKIN-1BETA, KNOWN TO ELICIT THE ACTIVATION CASCADE FOR NF-KAPPAB AND ACTIVATOR PROTEIN-1 THAT ARE RESPONSIBLE FOR TRANSCRIPTIONAL INDUCTION OF THESE CYTOKINES AMONG OTHER TARGET GENES, WHICH CONFORM A POSITIVE FEEDBACK LOOP FOR CONTINUATION AND EXPANSION OF THE INFLAMMATORY RESPONSES. IN ADDITION, COMPARATIVE GENE EXPRESSION PROFILE ANALYSES HAVE REVEALED ACTIVATION OF A NUMBER OF GENES THAT EXPLAIN THE "TRANSFORMED-LIKE" PHENOTYPE OF SYNOVIOCYTES. AMONG THE GENES EXPRESSED IN RHEUMATOID SYNOVIOCYTES UPON INFLAMMATORY STIMULI, INDUCTION OF GENE EXPRESSION OF NOTCH PROTEINS AND ITS LIGAND HAVE BEEN FOUND. POSSIBLE ROLES OF NOTCH SIGNALING IN RA SYNOVIOCYTES ARE DISCUSSED. 2005 6 6887 38 [ROLE OF METAFLAMMATION AS A SYSTEMIC MANIFESTATION OF METABOLIC DISEASES]. VISCERAL OBESITY AS A COMPONENT OF THE METABOLIC SYNDROME IS CHARACTERIZED BY SYSTEMIC AND LOCAL INFLAMMATION, WHICH CAN BE QUANTIFIED IN ORGANS (METAFLAMMATION). THIS PROCESS CAN BE REGARDED AS A CHRONIC, STERILE, AND LOW-GRADE STATE OF INFLAMMATION WITHOUT INFECTION, TRAUMA, TUMOR OR AUTOIMMUNITY. IT IS CAUSED BY AN INFLAMMATION OF THE VISCERAL ADIPOSE TISSUE (ADIPOSE INFLAMMATION OR ADIPOFLAMMATION) DUE TO ADIPOCYTE HYPERTROPHY AND HYPERPLASIA WITH INCREASED INFILTRATION BY MONOCYTES AND MACROPHAGES. IMPORTANT IS THE PRESENCE OF PROINFLAMMATORY, SO-CALLED POLARIZED M1 MACROPHAGES THAT ARE INDUCED BY INTERFERON GAMMA (IFN-GAMMA) AND LIPOPOLYSACCHARIDES (LPS) WITH SECRETION OF INTERLEUKIN (IL)-6, TUMOR NECROSIS FACTOR (TNF) AND IL?1. IN CONTRAST, THE ANTI-INFLAMMATORY, SO-CALLED POLARIZED M2 MACROPHAGES INDUCED BY IL?4 AND IL-13 WITH SECRETION OF IL?8 AND IL-10 DECREASE. IN ADDITION, THE SECRETED ADIPOKINE PATTERN CHANGES FROM ANTI-INFLAMMATORY TO PROINFLAMMATORY. ADIPOCYTE NECROSIS, LOCAL HYPOXIA, DYSREGULATED AUTOPHAGY, ACTIVATION OF INFLAMMASOMES, MODULATION OF TOLL-LIKE RECEPTORS, AND EPIGENETIC FACTORS PLAY A COMPLEX ROLE. THIS MECHANISM RESULTS IN LOCAL INSULIN RESISTANCE AND SUBSEQUENTLY A SYSTEMIC INSULIN RESISTANCE OF PERIPHERAL ORGANS AS WELL AS A SPILLOVER OF LOCAL MEDIATORS OF INFLAMMATION INTO THE SYSTEMIC CIRCULATION (MEASURED AS OBESITY C?REACTIVE PROTEIN, CRP). THE ACTIVATION OF INFLAMMATORY SIGNAL TRANSDUCTION CASCADES LEADS TO INHIBITORY PHOSPHORYLATION OF THE INSULIN SIGNALING PATHWAY AND A WEAKENING OF THE EFFECT OF INSULIN. IN PARALLEL, ECTOPIC LIPID ACCUMULATION OCCURS IN THE LIVER, MUSCULATURE, PANCREAS, PERICARDIUM AND LUNGS. DIACYLGLYCEROL (DAG) ACTIVATES SPECIFIC ISOFORMS OF PROTEIN KINASE C (EPSILON IN THE LIVER AND TAU IN THE MUSCULATURE), WHICH IN TURN LEAD TO INHIBITION OF THE INSULIN SIGNALING PATHWAY. INSULIN RESISTANCE IN OBESITY AND TYPE 2 DIABETES MELLITUS IS AN INFLAMMATORY DISEASE. THE AIM OF FUTURE TRANSLATIONAL APPROACHES IS AN ANTI-INFLAMMATORY, MOLECULARLY INDIVIDUALIZED (PRECISION MEDICINE) TREATMENT IN ADIPOSE TISSUE (TARGETED THERAPY) AND IN ORGANS OF INSULIN RESISTANCE. 2023 7 6865 28 [OXIDATIVE STRESS IN PROSTATE HYPERTROPHY AND CARCINOGENESIS]. AGING, SIGNIFICANT IMPAIRMENT OF THE OXIDATION/REDUCTION BALANCE, INFECTION, AND INFLAMMATION ARE RECOGNIZED RISK FACTORS OF BENIGN HYPERPLASIA AND PROSTATE CANCER. CHRONIC SYMPTOMATIC AND ASYMPTOMATIC PROSTATE INFLAMMATORY PROCESSES GENERATE SIGNIFICANTLY ELEVATED LEVELS OF REACTIVE OXYGEN AND NITROGEN SPECIES, AND HALOGENATED COMPOUNDS. PROSTATE CANCER PATIENTS SHOWED SIGNIFICANTLY HIGHER LIPID PEROXIDATION AND LOWER ANTIOXIDANT LEVELS IN PERIPHERAL BLOOD THAN HEALTHY CONTROLS, WHEREAS PATIENTS WITH PROSTATE HYPERPLASIA DID NOT SHOW SUCH SYMPTOMS. OXIDATIVE/NITROSATIVE/HALOGENATIVE STRESS CAUSES DNA MODIFICATIONS LEADING TO GENOME INSTABILITY THAT MAY INITIATE CARCINOGENESIS; HOWEVER, IT WAS SHOWN THAT OXIDATIVE DAMAGE ALONE IS NOT SUFFICIENT TO INITIATE THIS PROCESS. PEROXIDATION PRODUCTS INDUCED BY REACTIVE OXYGEN AND NITROGEN SPECIES SEEM TO TAKE PART IN EPIGENETIC MECHANISMS REGULATING GENOME ACTIVITY. ONE OF THE MOST COMMON CHANGES OCCURRING IN MORE THAN 90% OF ALL ANALYZED PROSTATE CANCERS IS THE SILENCING OF GSTP1 GENE ACTIVITY. THE GENE ENCODES GLUTATHIONE TRANSFERASE, AN ENZYME PARTICIPATING IN DETOXIFICATION PROCESSES. PROSTATE HYPERPLASIA IS OFTEN ACCOMPANIED BY CHRONIC INFLAMMATION AND SUCH A RELATIONSHIP WAS NOT OBSERVED IN PROSTATE CANCER. THE PARTICIPATION OF INFECTION AND INFLAMMATION IN THE DEVELOPMENT OF HYPERPLASIA IS UNQUESTIONABLE AND THESE FACTORS PROBABLY ALSO TAKE PART IN INITIATING THE EARLY STAGES OF PROSTATE CARCINOGENESIS. THUS IT SEEMS THAT THERAPEUTIC STRATEGIES THAT PREVENT GENOME OXIDATIVE DAMAGE IN SITUATIONS INVOLVING OXIDATIVE/NITROSATIVE/HALOGENATIVE STRESS, I.E. USE OF ANTIOXIDANTS, PLANT STEROIDS, ANTIBIOTICS, AND NON-STEROIDAL ANTI-INFLAMMATORY DRUGS, COULD HELP PREVENT CARCINOGENESIS. 2009 8 4412 38 MOLECULAR AND CELLULAR BASIS OF RHEUMATOID JOINT DESTRUCTION. RHEUMATOID ARTHRITIS (RA) IS A CHRONIC INFLAMMATORY DISEASE ASSOCIATED WITH JOINT DESTRUCTION. SYNOVIAL FIBROBLASTS ARE KEY PLAYERS IN THIS PATHOLOGICAL PROCESS. THEY FAVORISE A PRO-INFLAMMATORY ENVIRONMENT IN THE SYNOVIAL TISSUE, INTERACT WITH THE IMMUNE SYSTEM AND REGULATE THE DIFFERENTIATION OF MONOCYTES INTO OSTEOCLASTS. SYNOVIAL HYPERPLASIA IS ANOTHER CHARACTERISTIC OF RA, REFLECTING NOT ONLY AN IMBALANCE BETWEEN PROLIFERATION AND APOPTOSIS, BUT ALSO THE MIGRATION OF CELLS INTO THE SYNOVIAL TISSUE. GENE TRANSFER EXPERIMENTS HAVE BEEN USED AS IMPORTANT TOOLS FOR THE UNDERSTANDING OF MOLECULAR AND CELLULAR CHANGES THAT CHARACTERIZE THE ACTIVATED RA SYNOVIAL FIBROBLASTS. ACTIVATED SYNOVIAL FIBROBLASTS CAN INVADE CARTILAGE AND BONE. SYNOVIAL ACTIVATION IS DRIVEN BY CYTOKINES, SUCH AS TNFALPHA AND IL-1, AS WELL AS IL-15, 16, 17, 18, 22, 23, BUT ALSO BY CYTOKINE-INDEPENDENT MECHANISMS THAT INVOLVE THE INNATE IMMUNE SYSTEM (I.E. TLRS), A UNIQUE COMMUNICATION NETWORK OF MICROPARTICLES AND EPIGENETIC CHANGES (E.G. L1 RETROELEMENTS). 2006 9 4298 31 MICRORNA-146A GOVERNS FIBROBLAST ACTIVATION AND JOINT PATHOLOGY IN ARTHRITIS. SYNOVIAL FIBROBLASTS ARE KEY CELLS ORCHESTRATING THE INFLAMMATORY RESPONSE IN ARTHRITIS. HERE WE DEMONSTRATE THAT LOSS OF MIR-146A, A KEY EPIGENETIC REGULATOR OF THE INNATE IMMUNE RESPONSE, LEADS TO INCREASED JOINT DESTRUCTION IN A TNF-DRIVEN MODEL OF ARTHRITIS BY SPECIFICALLY REGULATING THE BEHAVIOR OF SYNOVIAL FIBROBLASTS. ABSENCE OF MIR-146A IN SYNOVIAL FIBROBLASTS DISPLAY A HIGHLY DEREGULATED GENE EXPRESSION PATTERN AND ENHANCED PROLIFERATION IN VITRO AND IN VIVO. DEFICIENCY OF MIR-146A INDUCES DEREGULATION OF TUMOR NECROSIS FACTOR (TNF) RECEPTOR ASSOCIATED FACTOR 6 (TRAF6) IN SYNOVIAL FIBROBLASTS, LEADING TO INCREASED PROLIFERATION. IN ADDITION, LOSS OF MIR-146A SHIFTS THE METABOLIC STATE OF FIBROBLASTS TOWARDS GLYCOLYSIS AND AUGMENTS THE ABILITY OF SYNOVIAL FIBROBLASTS TO SUPPORT THE GENERATION OF OSTEOCLASTS BY CONTROLLING THE BALANCE OF OSTEOCLASTOGENIC REGULATORY FACTORS RECEPTOR ACTIVATOR OF NF-KAPPAB LIGAND (RANKL) AND OSTEOPROTEGERIN (OPG). BONE MARROW TRANSPLANTATION EXPERIMENTS CONFIRMED THE IMPORTANCE OF MIR-146A IN THE RADIORESISTANT MESENCHYMAL COMPARTMENT FOR THE CONTROL OF ARTHRITIS SEVERITY, IN PARTICULAR FOR INFLAMMATORY JOINT DESTRUCTION. THIS STUDY THEREFORE IDENTIFIES MICRORNA-146A AS AN IMPORTANT LOCAL EPIGENETIC REGULATOR OF THE INFLAMMATORY RESPONSE IN ARTHRITIS. IT IS A CENTRAL ELEMENT OF AN ANTI-INFLAMMATORY FEEDBACK LOOP IN RESIDENT SYNOVIAL FIBROBLASTS, WHO ARE ORCHESTRATING THE INFLAMMATORY RESPONSE IN CHRONIC ARTHRITIS. MIR-146A RESTRICTS THEIR ACTIVATION, THEREBY PREVENTING EXCESSIVE TISSUE DAMAGE DURING ARTHRITIS. 2017 10 5507 26 RHEUMATOID ARTHRITIS PROGRESSION MEDIATED BY ACTIVATED SYNOVIAL FIBROBLASTS. RHEUMATOID ARTHRITIS (RA) IS A CHRONIC INFLAMMATORY DISEASE CHARACTERIZED BY SYNOVIAL HYPERPLASIA AND PROGRESSIVE JOINT DESTRUCTION. RHEUMATOID ARTHRITIS SYNOVIAL FIBROBLASTS (RASFS) ARE LEADING CELLS IN JOINT EROSION AND CONTRIBUTE ACTIVELY TO INFLAMMATION. RASFS SHOW AN ACTIVATED PHENOTYPE THAT IS INDEPENDENT OF THE INFLAMMATORY ENVIRONMENT AND REQUIRES THE COMBINATION OF SEVERAL FACTORS. ALTHOUGH NEW ASPECTS REGARDING RASF ACTIVATION VIA MATRIX DEGRADATION PRODUCTS, EPIGENETIC MODIFICATIONS, INFLAMMATORY FACTORS, TOLL-LIKE RECEPTOR (TLR) ACTIVATION AND OTHERS HAVE RECENTLY BEEN UNCOVERED, THE PRIMARY PATHOPHYSIOLOGICAL PROCESSES IN EARLY ARTHRITIS LEADING TO PERMANENT ACTIVATION ARE MOSTLY UNKNOWN. HERE, WE REVIEW NEW FINDINGS REGARDING RASF ACTIVATION AND THEIR ALTERED BEHAVIOR THAT CONTRIBUTE TO MATRIX DESTRUCTION AND INFLAMMATION AS WELL AS THEIR POTENTIAL TO SPREAD RA. 2010 11 799 26 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 12 4162 31 MECP2 REGULATES PTCH1 EXPRESSION THROUGH DNA METHYLATION IN RHEUMATOID ARTHRITIS. RHEUMATOID ARTHRITIS (RA) IS A CHRONIC AUTOIMMUNE INFLAMMATORY DISEASE, IN WHICH PATHOGENESIS IS NOT CLEAR. MANY RESEARCH DEMONSTRATED THAT FIBROBLAST-LIKE SYNOVIOCYTES (FLSS) PLAY A KEY ROLE IN RA PATHOGENESIS, JOIN IN THE CARTILAGE INJURY AND HYPERPLASIA OF THE SYNOVIUM, AND CONTRIBUTE TO THE RELEASE OF INFLAMMATORY CYTOKINES. WE USED ADJUVANT ARTHRITIS (AA) RATS AS RA ANIMAL MODELS. THE METHYL-CPG-BINDING PROTEIN 2 (MECP2) ENABLES THE SUPPRESSED CHROMATIN STRUCTURE TO BE SELECTIVELY DETECTED IN AA FLSS. OVEREXPRESSION OF THIS PROTEIN LEADS TO AN INCREASE OF INTEGRAL METHYLATION LEVELS. SOME RESEARCH HAS CONFIRMED THE HEDGEHOG (HH) SIGNALING PATHWAY PLAYS AN IMPORTANT ROLE IN RA PATHOGENESIS; FURTHERMORE, PATCHED 1 (PTCH1) IS A NEGATIVE FRACTION OF HH SIGNALING PATHWAY. WE USED 5-AZA-2'-DEOXYCYTIDINE (5-AZADC) AS DNA METHYLATION INHIBITOR. IN OUR RESEARCH, WE FOUND MECP2 REDUCED PTCH1 EXPRESSION IN AA FLSS; 5-AZADC OBSTRUCTED THE LOSS OF PTCH1 EXPRESSION. 5-AZADC, TREATMENT OF AA FLSS, ALSO BLOCKS THE RELEASE OF INFLAMMATORY CYTOKINES. IN ORDER TO PROBE THE POTENTIAL MOLECULAR MECHANISM, WE ASSUMED THE EPIGENETIC PARTICIPATION IN THE REGULATION OF PTCH1. RESULTS DEMONSTRATED THAT PTCH1 HYPERMETHYLATION IS RELATED TO THE PERSISTENT FLS ACTIVATION AND INFLAMMATION IN AA RATS. KNOCKDOWN OF MECP2 USING SMALL-INTERFERING RNA TECHNIQUE ADDED PTCH1 EXPRESSION IN AA FLSS. OUR RESULTS INDICATE THAT DNA METHYLATION MAY OFFER MOLECULE MECHANISMS, AND THE REDUCED PTCH1 METHYLATION LEVEL COULD REGULATE INFLAMMATION THROUGH KNOCKDOWN OF MECP2. GRAPHICAL ABSTRACT PTCH1 IS AN INHIBITORY PROTEIN OF THE HEDGEHOG SIGNALING PATHWAY. INCREASED EXPRESSION OF PTCH1 CAN INHIBIT THE EXPRESSION OF GLI1 AND SHH, THEREBY INHIBITING THE ACTIVATION OF HEDGEHOG SIGNALING PATHWAY. INACTIVATED HEDGEHOG SIGNALING PATHWAY INHIBITS THE SECRETION OF IL-6 AND TNF-ALPHA. MECP2 MEDIATES HYPERMETHYLATION OF PTCH1 GENE AND DECREASES THE EXPRESSION OF PTCH1 PROTEIN, THUS ACTIVATING HEDGEHOG SIGNALING PATHWAY AND INCREASING SECRETION OF IL-6 AND TNF-ALPHA. 2017 13 6741 35 WHERE TO STAND WITH STROMAL CELLS AND CHRONIC SYNOVITIS IN RHEUMATOID ARTHRITIS? THE SYNOVIUM EXERCISES ITS MAIN FUNCTION IN JOINT HOMEOSTASIS THROUGH THE SECRETION OF FACTORS (SUCH AS LUBRICIN AND HYALURONIC ACID) THAT ARE CRITICAL FOR THE JOINT LUBRICATION AND FUNCTION. THE MAIN SYNOVIUM CELL COMPONENTS ARE FIBROBLAST-LIKE SYNOVIOCYTES, MESENCHYMAL STROMAL/STEM CELLS AND MACROPHAGE-LIKE SYNOVIAL CELLS. IN THE SYNOVIUM, CELLS OF MESENCHYMAL ORIGIN MODULATE LOCAL INFLAMMATION AND FIBROSIS, AND INTERACT WITH DIFFERENT FIBROBLAST SUBTYPES AND WITH RESIDENT MACROPHAGES. IN PATHOLOGIC CONDITIONS, SUCH AS RHEUMATOID ARTHRITIS, FIBROBLAST-LIKE SYNOVIOCYTES PROLIFERATE ABNORMALLY, RECRUIT MESENCHYMAL STEM CELLS FROM SUBCHONDRAL BONE MARROW, AND INFLUENCE IMMUNE CELL ACTIVITY THROUGH EPIGENETIC AND METABOLIC ADAPTATIONS. THE RESULTING SYNOVIAL HYPERPLASIA LEADS TO SECONDARY CARTILAGE DESTRUCTION, JOINT SWELLING, AND PAIN. IN THE PRESENT REVIEW, WE SUMMARIZE RECENT FINDINGS ON THE MOLECULAR SIGNATURE AND THE ROLES OF STROMAL CELLS DURING SYNOVIAL PANNUS FORMATION AND RHEUMATOID ARTHRITIS PROGRESSION. 2019 14 4415 30 MOLECULAR AND CELLULAR MECHANISMS THAT INDUCE ARTERIAL CALCIFICATION BY INDOXYL SULFATE AND P-CRESYL SULFATE. THE PROTEIN-BOUND UREMIC TOXINS, INDOXYL SULFATE (IS) AND P-CRESYL SULFATE (PCS), ARE CONSIDERED TO BE HARMFUL VASCULAR TOXINS. ARTERIAL MEDIA CALCIFICATION, OR THE DEPOSITION OF CALCIUM PHOSPHATE CRYSTALS IN THE ARTERIES, CONTRIBUTES SIGNIFICANTLY TO CARDIOVASCULAR COMPLICATIONS, INCLUDING LEFT VENTRICULAR HYPERTROPHY, HYPERTENSION, AND IMPAIRED CORONARY PERFUSION IN THE ELDERLY AND PATIENTS WITH CHRONIC KIDNEY DISEASE (CKD) AND DIABETES. RECENTLY, WE REPORTED THAT BOTH IS AND PCS TRIGGER MODERATE TO SEVERE CALCIFICATION IN THE AORTA AND PERIPHERAL VESSELS OF CKD RATS. THIS REVIEW DESCRIBES THE MOLECULAR AND CELLULAR MECHANISMS BY WHICH THESE UREMIC TOXINS INDUCE ARTERIAL MEDIA CALCIFICATION. A COMPLEX INTERPLAY BETWEEN INFLAMMATION, COAGULATION, AND LIPID METABOLISM PATHWAYS, INFLUENCED BY EPIGENETIC FACTORS, IS CRUCIAL IN IS/PCS-INDUCED ARTERIAL MEDIA CALCIFICATION. HIGH LEVELS OF GLUCOSE ARE LINKED TO THESE EVENTS, SUGGESTING THAT A GOOD BALANCE BETWEEN GLUCOSE AND LIPID LEVELS MIGHT BE IMPORTANT. ON THE CELLULAR LEVEL, EFFECTS ON ENDOTHELIAL CELLS, WHICH ACT AS THE PRIMARY SENSORS OF CIRCULATING PATHOLOGICAL TRIGGERS, MIGHT BE AS IMPORTANT AS THOSE ON VASCULAR SMOOTH MUSCLE CELLS. ENDOTHELIAL DYSFUNCTION, PROVOKED BY IS AND PCS TRIGGERED OXIDATIVE STRESS, MAY BE CONSIDERED A KEY EVENT IN THE ONSET AND DEVELOPMENT OF ARTERIAL MEDIA CALCIFICATION. IN THIS REVIEW A NUMBER OF IMPORTANT OUTSTANDING QUESTIONS SUCH AS THE ROLE OF MIRNA'S, PHENOTYPIC SWITCHING OF BOTH ENDOTHELIAL AND VASCULAR SMOOTH MUSCLE CELLS AND NEW TYPES OF PROGRAMMED CELL DEATH IN ARTERIAL MEDIA CALCIFICATION RELATED TO PROTEIN-BOUND UREMIC TOXINS ARE PUT FORWARD AND DISCUSSED. 2020 15 2378 28 EPIGENETIC REGULATION OF VASCULAR SMOOTH MUSCLE CELL PHENOTYPE SWITCHING IN ATHEROSCLEROTIC ARTERY REMODELING: A MINI-REVIEW. ATHEROSCLEROSIS IS A CHRONIC INFLAMMATORY DISEASE CHARACTERIZED BY EXTENSIVE REMODELING OF MEDIUM AND LARGE-SIZED ARTERIES. INWARD REMODELING (=LUMEN SHRINKAGE) OF THE VASCULAR WALLS IS THE UNDERLYING CAUSE FOR ISCHEMIA IN TARGET ORGANS. THEREFORE, INWARD REMODELING CAN BE CONSIDERED THE PREDOMINANT FEATURE OF ATHEROSCLEROTIC PATHOLOGY. OUTWARD REMODELING (=LUMEN ENLARGEMENT) IS A PHYSIOLOGICAL RESPONSE COMPENSATING FOR LUMEN SHRINKAGE CAUSED BY NEOINTIMAL HYPERPLASIA, BUT AS A PATHOLOGICAL RESPONSE TO CHANGES IN BLOOD FLOW, OUTWARD REMODELING LEADS TO SUBSTANTIAL ARTERIAL WALL THINNING. THINNED VASCULAR WALLS ARE PRONE TO RUPTURE, AND SUBSEQUENT THROMBUS FORMATION ACCOUNTS FOR THE MAJORITY OF ACUTE CARDIOVASCULAR EVENTS. PATHOLOGICAL REMODELING IS DRIVEN BY INFLAMMATORY CELLS WHICH INDUCE VASCULAR SMOOTH MUSCLE CELLS TO SWITCH FROM QUIESCENT TO A PROLIFERATIVE AND MIGRATORY PHENOTYPE. AFTER DECADES OF INTENSIVE RESEARCH, THE MOLECULAR MECHANISMS OF ARTERIAL REMODELING ARE STARTING TO UNFOLD. IN THIS MINI-REVIEW, WE SUMMARIZE THE CURRENT KNOWLEDGE OF THE EPIGENETIC AND TRANSCRIPTIONAL REGULATION OF VASCULAR SMOOTH MUSCLE CELL PHENOTYPE SWITCHING FROM THE CONTRACTILE TO THE SYNTHETIC PHENOTYPE INVOLVED IN ARTERIAL REMODELING AND DISCUSS POTENTIAL THERAPEUTIC OPTIONS. 2021 16 2748 30 EXPRESSION AND FUNCTION OF EZH2 IN SYNOVIAL FIBROBLASTS: EPIGENETIC REPRESSION OF THE WNT INHIBITOR SFRP1 IN RHEUMATOID ARTHRITIS. OBJECTIVES: TO STUDY THE EXPRESSION, REGULATION AND FUNCTION OF THE HISTONE METHYLTRANSFERASE ENHANCER OF ZESTE HOMOLOGUE 2 (EZH2) IN SYNOVIAL FIBROBLASTS (SF) FROM PATIENTS WITH RHEUMATOID ARTHRITIS (RA) AND OSTEOARTHRITIS (OA). METHODS: SF WERE OBTAINED FROM RA AND OA PATIENTS UNDERGOING JOINT SURGERY. EXPRESSION LEVELS WERE ASSESSED BY QUANTITATIVE REAL-TIME PCR AND WESTERN BLOT. KINASE INHIBITORS AND REPORTER GENE ASSAYS WERE EMPLOYED TO STUDY SIGNALLING PATHWAYS. FUNCTIONAL ANALYSES INCLUDED EZH2 OVEREXPRESSION BY PLASMID TRANSFECTION AND GENE SILENCING BY SMALL INTERFERING RNA. CHROMATIN IMMUNOPRECIPITATION ASSAY WAS USED TO ANALYSE HISTONE METHYLATION WITHIN DISTINCT PROMOTER REGIONS. RESULTS: BY STUDYING THE EXPRESSION AND FUNCTION OF EZH2 IN SF THE AUTHORS FOUND THAT EZH2 IS OVEREXPRESSED IN RHEUMATOID ARTHRITIS SYNOVIAL FIBROBLASTS (RASF) AND FURTHER INDUCED BY TUMOUR NECROSIS FACTOR ALPHA THROUGH THE NUCLEAR FACTOR KAPPA B AND JUN KINASE PATHWAYS. AS A TARGET GENE OF EZH2 THE AUTHORS IDENTIFIED SECRETED FRIZZLED-RELATED PROTEIN 1 (SFRP1), AN INHIBITOR OF WNT SIGNALLING, WHICH IS ASSOCIATED WITH THE ACTIVATION OF RASF, AND SHOW THAT SFRP1 EXPRESSION CORRELATES WITH THE OCCUPATION OF ITS PROMOTER WITH ACTIVATING AND SILENCING HISTONE MARKS. CONCLUSIONS: THESE DATA STRONGLY SUGGEST THAT THE CHRONIC INFLAMMATORY ENVIRONMENT OF THE RA JOINT INDUCES EZH2 AND THUS MIGHT CAUSE CHANGES IN THE EPIGENETIC PROGRAMMES OF SF. 2011 17 4116 26 MECHANISMS OF AIRWAY EPITHELIAL INJURY AND ABNORMAL REPAIR IN ASTHMA AND COPD. THE AIRWAY EPITHELIUM COMPRISES OF DIFFERENT CELL TYPES AND ACTS AS A PHYSICAL BARRIER PREVENTING PATHOGENS, INCLUDING INHALED PARTICLES AND MICROBES, FROM ENTERING THE LUNGS. GOBLET CELLS AND SUBMUCOSAL GLANDS PRODUCE MUCUS THAT TRAPS PATHOGENS, WHICH ARE EXPELLED FROM THE RESPIRATORY TRACT BY CILIATED CELLS. BASAL CELLS ACT AS PROGENITOR CELLS, DIFFERENTIATING INTO DIFFERENT EPITHELIAL CELL TYPES, TO MAINTAIN HOMEOSTASIS FOLLOWING INJURY. ADHERENS AND TIGHT JUNCTIONS BETWEEN CELLS MAINTAIN THE EPITHELIAL BARRIER FUNCTION AND REGULATE THE MOVEMENT OF MOLECULES ACROSS IT. IN THIS REVIEW WE DISCUSS HOW ABNORMAL EPITHELIAL STRUCTURE AND FUNCTION, CAUSED BY CHRONIC INJURY AND ABNORMAL REPAIR, DRIVES AIRWAY DISEASE AND SPECIFICALLY ASTHMA AND CHRONIC OBSTRUCTIVE PULMONARY DISEASE (COPD). IN BOTH DISEASES, INHALED ALLERGENS, POLLUTANTS AND MICROBES DISRUPT JUNCTIONAL COMPLEXES AND PROMOTE CELL DEATH, IMPAIRING THE BARRIER FUNCTION AND LEADING TO INCREASED PENETRATION OF PATHOGENS AND A CONSTANT AIRWAY IMMUNE RESPONSE. IN ASTHMA, THE INFLAMMATORY RESPONSE PRECIPITATES THE EPITHELIAL INJURY AND DRIVES ABNORMAL BASAL CELL DIFFERENTIATION. THIS LEADS TO REDUCED CILIATED CELLS, GOBLET CELL HYPERPLASIA AND INCREASED EPITHELIAL MESENCHYMAL TRANSITION, WHICH CONTRIBUTE TO IMPAIRED MUCOCILIARY CLEARANCE AND AIRWAY REMODELLING. IN COPD, CHRONIC OXIDATIVE STRESS AND INFLAMMATION TRIGGER PREMATURE EPITHELIAL CELL SENESCENCE, WHICH CONTRIBUTES TO LOSS OF EPITHELIAL INTEGRITY AND AIRWAY INFLAMMATION AND REMODELLING. INCREASED NUMBERS OF BASAL CELLS SHOWING DEREGULATED DIFFERENTIATION, CONTRIBUTES TO CILIARY DYSFUNCTION AND MUCOUS HYPERPRODUCTION IN COPD AIRWAYS. DEFECTIVE ANTIOXIDANT, ANTIVIRAL AND DAMAGE REPAIR MECHANISMS, POSSIBLY DUE TO GENETIC OR EPIGENETIC FACTORS, MAY CONFER SUSCEPTIBILITY TO AIRWAY EPITHELIAL DYSFUNCTION IN THESE DISEASES. THE CURRENT EVIDENCE SUGGESTS THAT A CONSTANT CYCLE OF INJURY AND ABNORMAL REPAIR OF THE EPITHELIUM DRIVES CHRONIC AIRWAY INFLAMMATION AND REMODELLING IN ASTHMA AND COPD. MECHANISTIC UNDERSTANDING OF INJURY SUSCEPTIBILITY AND DAMAGE RESPONSE MAY LEAD TO IMPROVED THERAPIES FOR THESE DISEASES. 2023 18 4044 23 MACROPHAGES IN OXIDATIVE STRESS AND MODELS TO EVALUATE THE ANTIOXIDANT FUNCTION OF DIETARY NATURAL COMPOUNDS. ANTIOXIDANT TESTING OF NATURAL PRODUCTS HAS ATTRACTED INCREASING INTEREST IN RECENT YEARS, MAINLY DUE TO THE FACT THAT AN ANTIOXIDANT-RICH DIET MIGHT PROVIDE HEALTH BENEFITS. ACTIVATED MACROPHAGES ARE A MAJOR SOURCE OF REACTIVE OXYGEN SPECIES, REACTIVE NITROGEN SPECIES, AND PEROXYNITRITE GENERATED THROUGH THE SO-CALLED RESPIRATORY BURST. CONSTITUTIVELY RELEASED PROINFLAMMATORY CYTOKINE, ESPECIALLY TUMOR NECROSIS FACTOR-ALPHA, TRIGGERS NUCLEAR FACTOR-KAPPAB, AND ACTIVATOR PROTEIN-1 TRANSLOCATION LEADING TO THE OVER PRODUCTION OF REACTIVE OXYGEN SPECIES AND REACTIVE NITROGEN SPECIES IN MACROPHAGES. ACTIVATION OF TRANSCRIPTION FACTORS IN THE LONG-LIVED TISSUE-RESIDENT MACROPHAGES AND/OR MONOCYTE-DERIVED MACROPHAGES, TRIGGER EPIGENETIC MODIFICATIONS LEADING TO THE PATHOGENESIS OF CHRONIC DISEASES. NUTRACEUTICALS INCLUDING LIPID RAFT STRUCTURE DISRUPTION AGENT, CHOLESTEROL DEPLETION AGENT, FARNESYLTRANSFERASE INHIBITOR, NUCLEAR FACTOR-KAPPAB BLOCKER (ALPHA,BETA-UNSATURATED CARBONYL COMPOUNDS), GLUCOCORTICOID RECEPTOR AGONIST, AND PEROXISOME PROLIFERATOR-ACTIVATED RECEPTOR-GAMMA AGONIST HAVE LONG BEEN USED TO INACTIVE MACROPHAGE. THE INHIBITION EFFECTS ON THE FORMATION OF NITRIC OXIDE, SUPEROXIDE, AND NITRITE PEROXIDE MAY BE RESPONSIBLE FOR THE ANTI-INFLAMMATORY FUNCTIONALITIES. ACTIVATED MACROPHAGE MODELS COULD BE USED TO IDENTIFY THE ACTIVE COMPONENTS FOR FUNCTIONAL DIETS DEVELOPMENT THROUGH A MULTIPLE TARGETS STRATEGY. 2017 19 3934 35 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 20 1665 29 DOWNREGULATION OF KIDNEY PROTECTIVE FACTORS BY INFLAMMATION: ROLE OF TRANSCRIPTION FACTORS AND EPIGENETIC MECHANISMS. CHRONIC KIDNEY DISEASE (CKD) IS ASSOCIATED TO AN INCREASED RISK OF DEATH, CKD PROGRESSION, AND ACUTE KIDNEY INJURY (AKI) EVEN FROM EARLY STAGES, WHEN GLOMERULAR FILTRATION RATE (GFR) IS PRESERVED. THE LINK BETWEEN EARLY CKD AND THESE RISKS IS UNCLEAR, SINCE THERE IS NO ACCUMULATION OF UREMIC TOXINS. HOWEVER, PATHOLOGICAL ALBUMINURIA AND KIDNEY INFLAMMATION ARE FREQUENT FEATURES OF EARLY CKD, AND THE PRODUCTION OF KIDNEY PROTECTIVE FACTORS MAY BE DECREASED. INDEED, KLOTHO EXPRESSION IS ALREADY DECREASED IN CKD CATEGORY G1 (NORMAL GFR). KLOTHO HAS ANTI-AGING AND NEPHROPROTECTIVE PROPERTIES, AND DECREASED KLOTHO LEVELS MAY CONTRIBUTE TO INCREASE THE RISK OF DEATH, CKD PROGRESSION, AND AKI. IN THIS REVIEW, WE DISCUSS THE DOWNREGULATION BY MEDIATORS OF INFLAMMATION OF MOLECULES WITH SYSTEMIC AND/OR RENAL LOCAL PROTECTIVE FUNCTIONS, EXEMPLIFIED BY KLOTHO AND PEROXISOME PROLIFERATOR-ACTIVATED RECEPTOR GAMMA COACTIVATOR-1ALPHA (PGC-1ALPHA), A TRANSCRIPTION FACTOR THAT PROMOTES MITOCHONDRIAL BIOGENESIS. CYTOKINES SUCH AS TWEAK, TNF-ALPHA, OR TRANSFORMING GROWTH FACTOR -BETA1 PRODUCED LOCALLY DURING KIDNEY INJURY OR RELEASED FROM INFLAMMATORY SITES AT OTHER ORGANS MAY DECREASE KIDNEY EXPRESSION OF KLOTHO AND PGC-1ALPHA OR LEAD TO SUBOPTIMAL RECRUITMENT OF THESE NEPHROPROTECTIVE PROTEINS. TRANSCRIPTION FACTORS (E.G., SMAD3 AND NF-KAPPAB) AND EPIGENETIC MECHANISMS (E.G., HISTONE ACETYLATION OR METHYLATION) CONTRIBUTE TO DOWNREGULATE THE EXPRESSION OF KLOTHO AND/OR PGC-1ALPHA, WHILE HISTONE CROTONYLATION PROMOTES PGC-1ALPHA EXPRESSION. NF-KAPPABIZ FACILITATES THE REPRESSIVE EFFECT OF NF-KAPPAB ON KLOTHO EXPRESSION. A DETAILED UNDERSTANDING OF THESE MEDIATORS MAY CONTRIBUTE TO THE DEVELOPMENT OF NOVEL THERAPEUTIC APPROACHES TO PREVENT CKD PROGRESSION AND ITS NEGATIVE IMPACT ON MORTALITY AND AKI. 2016