1 4880 80 OVERVIEW OF MMP-13 AS A PROMISING TARGET FOR THE TREATMENT OF OSTEOARTHRITIS. OSTEOARTHRITIS (OA) IS A COMMON DEGENERATIVE DISEASE CHARACTERIZED BY THE DESTRUCTION OF ARTICULAR CARTILAGE AND CHRONIC INFLAMMATION OF SURROUNDING TISSUES. MATRIX METALLOPROTEINASE-13 (MMP-13) IS THE PRIMARY MMP INVOLVED IN CARTILAGE DEGRADATION THROUGH ITS PARTICULAR ABILITY TO CLEAVE TYPE II COLLAGEN. HENCE, IT IS AN ATTRACTIVE TARGET FOR THE TREATMENT OF OA. HOWEVER, THE DETAILED MOLECULAR MECHANISMS OF OA INITIATION AND PROGRESSION REMAIN ELUSIVE, AND, CURRENTLY, THERE ARE NO INTERVENTIONS AVAILABLE TO RESTORE DEGRADED CARTILAGE. THIS REVIEW FULLY ILLUSTRATES THE INVOLVEMENT OF MMP-13 IN THE INITIATION AND PROGRESSION OF OA THROUGH THE REGULATION OF MMP-13 ACTIVITY AT THE MOLECULAR AND EPIGENETIC LEVELS, AS WELL AS THE STRATEGIES THAT HAVE BEEN EMPLOYED AGAINST MMP-13. THE AIM OF THIS REVIEW IS TO IDENTIFY MMP-13 AS AN ATTRACTIVE TARGET FOR INHIBITOR DEVELOPMENT IN THE TREATMENT OF OA. 2021 2 4679 35 NEW MOLECULAR TARGETS FOR THE TREATMENT OF OSTEOARTHRITIS. OSTEOARTHRITIS (OA) IS A CHRONIC DEGENERATIVE JOINT DISORDER CHARACTERIZED BY DESTRUCTION OF THE ARTICULAR CARTILAGE, SUBCHONDRAL BONE ALTERATIONS AND SYNOVITIS. CURRENT TREATMENTS ARE FOCUSED ON SYMPTOMATIC RELIEF BUT THEY LACK EFFICACY TO CONTROL THE PROGRESSION OF THIS DISEASE WHICH IS A LEADING CAUSE OF DISABILITY. THEREFORE, THE DEVELOPMENT OF EFFECTIVE DISEASE-MODIFYING DRUGS IS URGENTLY NEEDED. DIFFERENT INITIATIVES ARE IN PROGRESS TO DEFINE THE MOLECULAR MECHANISMS INVOLVED IN THE INITIATION AND PROGRESSION OF OA. THESE STUDIES SUPPORT THE THERAPEUTIC POTENTIAL OF PATHWAYS RELEVANT IN JOINT METABOLISM SUCH AS WNT/BETA-CATENIN, DISCOIDIN DOMAIN RECEPTOR 2 OR PROTEINASE-ACTIVATED RECEPTOR 2. THE DYSREGULATION IN CARTILAGE CATABOLISM AND SUBCHONDRAL BONE REMODELING COULD BE IMPROVED BY SELECTIVE INHIBITORS OF MATRIX METALLOPROTEINASES, AGGRECANASES AND OTHER PROTEASES. ANOTHER APPROACH WOULD FAVOR THE ACTIVITY OF ANABOLIC PROCESSES BY USING GROWTH FACTORS OR REGULATORY MOLECULES. RECENT STUDIES HAVE ALSO REVEALED THE ROLE OF OXIDATIVE STRESS AND SYNOVITIS IN THE PROGRESSION OF THIS DISEASE, SUPPORTING THE DEVELOPMENT OF A NUMBER OF INHIBITORY STRATEGIES. NOVEL TARGETS IN OA ARE REPRESENTED BY GENES INVOLVED IN OA PATHOPHYSIOLOGY DISCOVERED USING GENE NETWORK, EPIGENETIC AND MICRORNA APPROACHES. FURTHER INSIGHTS INTO THE MOLECULAR MECHANISMS INVOLVED IN OA INITIATION AND PROGRESSION MAY LEAD TO THE DEVELOPMENT OF NEW THERAPIES ABLE TO CONTROL JOINT DESTRUCTION AND REPAIR. 2010 3 3355 31 HISTONE EXTRACTION FROM HUMAN ARTICULAR CARTILAGE FOR THE STUDY OF EPIGENETIC REGULATION IN OSTEOARTHRITIS. OSTEOARTHRITIS (OA) IS A CHRONIC DISEASE THAT AFFECTS ARTICULAR CARTILAGE, CAUSING ITS DEGENERATION. ALTHOUGH OA IS ONE OF THE MOST PREVALENT PATHOLOGIES GLOBALLY, THERE ARE NO DEFINITIVE TREATMENTS AVAILABLE. RECENTLY, RESEARCH HAS FOCUSED ON ELUCIDATING THE COMPLEX INTERPLAY THAT TAKES PLACE BETWEEN INFLAMMATORY PROCESSES AND EPIGENETIC REGULATION, SHOWING THAT HISTONE POST-TRANSLATIONAL MODIFICATIONS (PTMS) CAN EXERT A PRONOUNCED EFFECT ON THE EXPRESSION OF OA-RELATED GENES. OA CHONDROCYTES ENHANCE THE PRODUCTION OF INTERLEUKIN 1BETA (IL-1BETA) AND INTERLEUKIN 8 (IL-8), WHICH ARE EPIGENETICALLY REGULATED. THESE CYTOKINES UPREGULATE THE SYNTHESIS OF MATRIX METALLOPROTEINASES (MMPS) AND AGGRECANASES, WHICH PROMOTE THE EXTRACELLULAR MATRIX (ECM) DESTRUCTION. THIS MOTIVATES THE STUDY OF HISTONE PTMS TO INVESTIGATE THE EPIGENETIC REGULATION OF PROINFLAMMATORY MOLECULES, BUT THE ABSENCE OF SPECIFIC PROTOCOLS TO EXTRACT HISTONES FROM HUMAN ARTICULAR CARTILAGE HAS COMPLICATED THIS TASK. THE LACK OF EFFECTIVE METHODS CAN BE EXPLAINED BY THE STRUCTURAL COMPLEXITY AND LOW CELLULARITY OF THIS TISSUE, WHICH ARE RESPONSIBLE FOR THE BIOMECHANICAL PROPERTIES THAT ALLOW THE MOVEMENT OF THE JOINT BUT ALSO COMPLICATE HISTONE ISOLATION. HERE, WE PROVIDE A HISTONE EXTRACTION PROCEDURE SPECIFICALLY ADAPTED FOR CRYOPRESERVED HUMAN ARTICULAR CARTILAGE THAT CAN BE USEFUL TO UNDERSTAND EPIGENETIC REGULATION IN OA AND ACCELERATE THE SEARCH FOR NOVEL STRATEGIES. 2022 4 2550 30 EPIGENETICS IN OSTEOARTHRITIS: POTENTIAL OF HDAC INHIBITORS AS THERAPEUTICS. OSTEOARTHRITIS (OA) IS THE MOST COMMON JOINT DISEASE AND THE LEADING CAUSE OF CHRONIC DISABILITY IN MIDDLE-AGED AND OLDER POPULATIONS WORLDWIDE. THE DEVELOPMENT OF DISEASE MODIFYING THERAPY FOR OA IS IN ITS INFANCY LARGELY BECAUSE THE REGULATORY MECHANISMS FOR THE MOLECULAR EFFECTORS OF OA PATHOGENESIS ARE POORLY UNDERSTOOD. RECENT STUDIES IDENTIFIED EPIGENETIC EVENTS AS A CRITICAL REGULATOR OF MOLECULAR PLAYERS INVOLVED IN THE INDUCTION AND DEVELOPMENT OF OA. EPIGENETIC MECHANISMS INCLUDE DNA METHYLATION, NON-CODING RNA AND HISTONE MODIFICATIONS. THE AIM OF THIS REVIEW IS TO BRIEFLY HIGHLIGHT THE RECENT ADVANCES IN THE EPIGENETICS OF CARTILAGE AND POTENTIAL OF HDACS (HISTONE DEACETYLASES) INHIBITORS IN THE THERAPEUTIC MANAGEMENT OF OA. WE SUMMARIZE THE RECENT STUDIES UTILIZING HDAC INHIBITORS AS POTENTIAL THERAPEUTICS FOR INHIBITING DISEASE PROGRESSION AND PREVENTING THE CARTILAGE DESTRUCTION IN OA. HDACS CONTROL NORMAL CARTILAGE DEVELOPMENT AND HOMEOSTASIS AND UNDERSTANDING THE IMPACT OF HDACS INHIBITORS ON THE DISEASE PATHOGENESIS IS OF INTEREST BECAUSE OF ITS IMPORTANCE IN AFFECTING OVERALL CARTILAGE HEALTH AND HOMEOSTASIS. THESE FINDINGS ALSO SHED NEW LIGHT ON CARTILAGE DISEASE PATHOPHYSIOLOGY AND PROVIDE SUBSTANTIAL EVIDENCE THAT HDACS MAY BE POTENTIAL NOVEL THERAPEUTIC TARGETS IN OA. 2018 5 2508 28 EPIGENETICS AND OSTEOARTHRITIS. OSTEOARTHRITIS (OA) IS THE MOST COMMON FORM OF JOINT DISEASE AND THE LEADING CAUSE OF CHRONIC DISABILITY IN MIDDLE-AGED AND OLDER POPULATIONS. THE DEVELOPMENT OF DISEASE-MODIFYING THERAPY FOR OA CURRENTLY FACES MAJOR OBSTACLES LARGELY BECAUSE THE REGULATORY MECHANISMS FOR THE FUNCTION OF JOINT TISSUE CELLS REMAIN UNCLEAR. PREVIOUS STUDIES HAVE FOUND THAT THE ALTERATIONS IN GENE EXPRESSION OF SPECIFIC TRANSCRIPTION FACTORS (TFS), PRO- OR ANTI-INFLAMMATORY CYTOKINES, MATRIX PROTEINASES AND EXTRACELLULAR MATRIX (ECM) PROTEINS IN ARTICULAR CARTILAGE MAY BE INVOLVED IN THE DEVELOPMENT OF OA. HOWEVER, THE REGULATORY MECHANISMS FOR THE EXPRESSION OF THOSE GENES IN OA CHONDROCYTES ARE LARGELY UNKNOWN. THE RECENT ADVANCES IN EPIGENETIC STUDIES HAVE SHED LIGHTS ON THE IMPORTANCE OF EPIGENETIC REGULATION OF GENE EXPRESSION IN THE DEVELOPMENT OF OA. IN THIS REVIEW, WE SUMMARIZE AND DISCUSS THE RECENT STUDIES ON THE REGULATORY ROLES OF VARIOUS EPIGENETIC MECHANISMS IN THE EXPRESSION OF GENES FOR SPECIFIC TFS, CYTOKINES, ECM PROTEINS AND MATRIX PROTEINASES, AS WELL THE SIGNIFICANCE OF THESE EPIGENETIC MECHANISMS IN THE PATHOGENESIS OF OA. 2015 6 3800 33 INTERPLAY OF INFLAMMATORY MEDIATORS WITH EPIGENETICS AND CARTILAGE MODIFICATIONS IN OSTEOARTHRITIS. OSTEOARTHRITIS (OA), A DEGENERATIVE DISEASE OF DIARTHRODIAL JOINTS, IS INFLUENCED BY MECHANICAL AND INFLAMMATORY FACTORS WITH AGING, OBESITY, CHRONIC INJURIES, AND SECONDARY DISEASES THOUGHT TO BE MAJOR FACTORS DRIVING THE PROCESS OF ARTICULAR CARTILAGE DEGENERATION. CHONDROCYTES, THE CELLULAR COMPONENT OF CARTILAGE, RESIDE IN AN AVASCULAR ENVIRONMENT AND NORMALLY HAVE LIMITED POTENTIAL TO REPLICATE. HOWEVER, EXTRINSIC FACTORS SUCH AS INJURY TO THE JOINT OR INTRINSIC ALTERATIONS TO THE CHONDROCYTES THEMSELVES CAN LEAD TO AN ALTERED PHENOTYPE AND DEVELOPMENT OF OA. SYNOVIAL INFLAMMATION IS ALSO A PIVOTAL ELEMENT OF THE OSTEOARTHRITIC, DEGENERATIVE PROCESS: INFLUX OF PRO-INFLAMMATORY CYTOKINES AND PRODUCTION OF MATRIX METALLOPROTEINASES ACCELERATE ADVANCED CELLULAR PROCESSES SUCH AS SYNOVITIS AND CARTILAGE DAMAGE. AS WELL AS A GENETIC INPUT, RECENT DATA HAVE HIGHLIGHTED EPIGENETIC FACTORS AS CONTRIBUTING TO DISEASE. STUDIES CONDUCTED OVER THE LAST DECADE HAVE FOCUSED ON THREE KEY ASPECTS IN OA; INFLAMMATION AND THE IMMUNE RESPONSE, GENOME-WIDE ASSOCIATION STUDIES THAT HAVE IDENTIFIED IMPORTANT GENES UNDERGOING EPIGENETIC MODIFICATIONS, AND FINALLY HOW CHONDROCYTES TRANSFORM IN THEIR FUNCTION DURING DEVELOPMENT AND DISEASE. DATA HIGHLIGHTED HERE HAVE IDENTIFIED CRITICAL INFLAMMATORY GENES INVOLVED IN OA AND HOW THESE FACTORS IMPACT CHONDROCYTE HYPERTROPHY IN THE DISEASE. THIS REVIEW ALSO ADDRESSES KEY INFLAMMATORY FACTORS IN SYNOVIAL INFLAMMATION, EPIGENETICS, AND CHONDROCYTE FATE, AND HOW AGENTS THAT INHIBIT EPIGENETIC MECHANISMS LIKE DNA METHYLATION AND HISTONE MODIFICATIONS COULD AID IN DEVELOPMENT OF LONG-TERM TREATMENT STRATEGIES FOR THE DISEASE. 2018 7 2309 35 EPIGENETIC REGULATION OF CHONDROCYTES AND SUBCHONDRAL BONE IN OSTEOARTHRITIS. THE AIM OF THIS REVIEW IS TO PROVIDE AN UPDATED REVIEW OF THE EPIGENETIC FACTORS INVOLVED IN THE ONSET AND DEVELOPMENT OF OSTEOARTHRITIS (OA). OA IS A PREVALENT DEGENERATIVE JOINT DISEASE CHARACTERIZED BY CHRONIC INFLAMMATION, ECTOPIC BONE FORMATION WITHIN THE JOINT, AND PHYSICAL AND PROTEOLYTIC CARTILAGE DEGRADATION WHICH RESULT IN CHRONIC PAIN AND LOSS OF MOBILITY. AT PRESENT, NO DISEASE-MODIFYING THERAPEUTICS EXIST FOR THE PREVENTION OR TREATMENT OF THE DISEASE. RESEARCH HAS IDENTIFIED SEVERAL OA RISK FACTORS INCLUDING MECHANICAL STRESSORS, PHYSICAL ACTIVITY, OBESITY, TRAUMATIC JOINT INJURY, GENETIC PREDISPOSITION, AND AGE. RECENTLY, THERE HAS BEEN INCREASED INTEREST IN IDENTIFYING EPIGENETIC FACTORS INVOLVED IN THE PATHOGENESIS OF OA. IN THIS REVIEW, WE DETAIL SEVERAL OF THESE EPIGENETIC MODIFICATIONS WITH KNOWN FUNCTIONS IN THE ONSET AND PROGRESSION OF THE DISEASE. WE ALSO REVIEW CURRENT THERAPEUTICS TARGETING ABERRANT EPIGENETIC REGULATION AS POTENTIAL OPTIONS FOR PREVENTIVE OR THERAPEUTIC TREATMENT. 2022 8 2460 29 EPIGENETIC THERAPIES FOR OSTEOARTHRITIS. OSTEOARTHRITIS (OA) IS AN AGE-ASSOCIATED DISEASE CHARACTERIZED BY CHRONIC JOINT PAIN RESULTING FROM DEGRADATION OF ARTICULAR CARTILAGE, INFLAMMATION OF THE SYNOVIAL LINING, AND CHANGES TO THE SUBCHONDRAL BONE. DESPITE THE WIDE PREVALENCE, NO FDA-APPROVED DISEASE-MODIFYING DRUGS EXIST. RECENT EVIDENCE HAS DEMONSTRATED THAT EPIGENETIC DYSREGULATION OF MULTIPLE MOLECULAR PATHWAYS UNDERLIES OA PATHOGENESIS, PROVIDING A NEW MECHANISTIC AND THERAPEUTIC AXIS WITH THE ADVANTAGE OF TARGETING MULTIPLE DEREGULATED PATHWAYS SIMULTANEOUSLY. IN THIS REVIEW, WE FOCUS ON THE EPIGENETIC REGULATORS THAT HAVE BEEN IMPLICATED IN OA, THEIR INDIVIDUAL ROLES, AND POTENTIAL CROSSTALK. FINALLY, WE DISCUSS THE PHARMACOLOGICAL MOLECULES THAT CAN MODULATE THEIR ACTIVITIES AND DISCUSS THE POTENTIAL ADVANTAGES AND CHALLENGES ASSOCIATED WITH EPIGENOME-BASED THERAPEUTICS FOR OA. 2020 9 2232 34 EPIGENETIC MODIFICATIONS OF MIRNAS IN OSTEOARTHRITIS: A SYSTEMATIC REVIEW ON THEIR METHYLATION LEVELS AND EFFECTS ON CHONDROCYTES, EXTRACELLULAR MATRIX AND JOINT INFLAMMATION. OSTEOARTHRITIS (OA) IS A JOINT DISORDER CHARACTERIZED BY PROGRESSIVE DEGENERATION OF CARTILAGE EXTRACELLULAR MATRIX (ECM), CHONDROCYTE HYPERTROPHY AND APOPTOSIS AND INFLAMMATION. THE CURRENT TREATMENTS MAINLY CONCERN PAIN CONTROL AND REDUCTION OF INFLAMMATION, BUT NO THERAPEUTIC STRATEGY HAS BEEN IDENTIFIED AS A DISEASE-MODIFYING TREATMENT. THEREFORE, IDENTIFYING SPECIFIC BIOMARKERS USEFUL TO PREVENT, TREAT OR DISTINGUISH THE STAGES OF OA DISEASE HAS BECOME AN IMMEDIATE NEED OF CLINICAL PRACTICE. THE ROLE OF MICRORNAS (MIRNAS) IN OA HAS BEEN INVESTIGATED IN THE LAST DECADE, AND INCREASING EVIDENCE HAS EMERGED THAT THE INFLUENCE OF THE ENVIRONMENT ON GENE EXPRESSION THROUGH EPIGENETIC PROCESSES CONTRIBUTES TO THE DEVELOPMENT, PROGRESSION AND AGGRESSIVENESS OF OA, IN PARTICULAR ACTING ON THE MICROENVIRONMENT MODULATIONS. THE EFFECTS OF EPIGENETIC REGULATION, PARTICULARLY DIFFERENT MIRNA METHYLATION DURING OA DISEASE, WERE HIGHLIGHTED IN THE PRESENT SYSTEMATIC REVIEW. THE EVIDENCE ARISING FROM THIS STUDY OF THE LITERATURE CONDUCTED IN THREE DATABASES (PUBMED, SCOPUS, WEB OF SCIENCE) SUGGESTED THAT MIRNA METHYLATION STATE ALREADY STRONGLY IMPACTS OA PROGRESSION, DRIVING CHONDROCYTES AND SYNOVIOCYTE PROLIFERATION, APOPTOSIS, INFLAMMATION AND ECM DEPOSITION. HOWEVER, THE POSSIBILITY OF UNDERSTANDING THE MECHANISM BY WHICH DIFFERENT EPIGENETIC MODIFICATIONS OF MIRNA OR PRE-MIRNA SEQUENCES DRIVE THE AGGRESSIVENESS OF OA COULD BE THE NEW FOCUS OF FUTURE INVESTIGATIONS. 2023 10 1878 23 EMERGING ROLES OF LONG NONCODING RNA IN CHONDROGENESIS, OSTEOGENESIS, AND OSTEOARTHRITIS. OSTEOARTHRITIS (OA) IS THE MOST PREVALENT AGE-RELATED DEBILITATING JOINT DISEASE, AND IS CHARACTERIZED PRIMARILY BY ARTICULAR CARTILAGE DEGRADATION AND SUBCHONDRAL BONE LESIONS. IT IS ALSO THE LEADING CAUSE OF CHRONIC MORBIDITY IN OLDER POPULATIONS. THE ETIOLOGY OF OA IS MULTIFACTORIAL, WITH THE UNDERLYING REGULATORY MECHANISMS REMAINING LARGELY UNKNOWN. LONG NONCODING RNA (LNCRNA) IS A GROUP OF NONCODING RNAS DEFINED AS BEING >200 NUCLEOTIDES IN LENGTH. INCREASING EVIDENCE DEMONSTRATES THAT MANY LNCRNAS SERVE AS CRITICAL REGULATORS OF CHONDROGENESIS AND BONE AND CARTILAGE HOMEOSTASIS, THEREBY INFLUENCING OA DEVELOPMENT. IN THIS REVIEW, WE HIGHLIGHT THE CURRENT UNDERSTANDING CONCERNING LNCRNAS, INCLUDING THEIR PHYSICAL FEATURES, BIOLOGICAL FUNCTIONS, AND POTENTIAL ROLES IN CHONDROGENESIS, OSTEOGENESIS, AND OA. THIS INFORMATION MAY SHED NEW LIGHT ON THE EPIGENETIC REGULATION OF CARTILAGE AND SUBSTANTIATE LNCRNAS AS NOVEL THERAPEUTIC TARGETS IN OA. 2019 11 4289 24 MICRORNA IN OSTEOARTHRITIS. OSTEOARTHRITIS (OA) IS THE MOST PREVALENT DEGENERATIVE JOINT DISEASE AND IS ACCOMPANIED BY PAIN AND JOINT DYSFUNCTION. ITS CLINICAL TREATMENT TENDS TO BE UNSATISFACTORY. NOVEL TARGETS IN OA INCLUDE GENES THAT ARE INVOLVED IN OA PATHOPHYSIOLOGY AND HAVE BEEN DISCOVERED USING GENE NETWORK, EPIGENETIC AND MICRORNA (MIRNA) APPROACHES. MIRNA HAS BEEN IMPLICATED IN IMPORTANT CELLULAR PROCESSES SUCH AS LIPID METABOLISM, APOPTOSIS, DIFFERENTIATION AND ORGAN DEVELOPMENT. THE IMPORTANCE OF MIRNA REGULATION IN CELLULAR FUNCTION IS BECOMING INCREASINGLY CLEAR AS NEW MIRNA TARGETS ARE REVEALED. THE PRESENT REVIEW SUMMARIZES THE CURRENT EVIDENCE OF THE IMPORTANT ROLE PLAYED BY MIRNA IN DETERMINING THE COMPLEX GENE EXPRESSION PATTERNS OF OA CHONDROCYTES AND THEIR ROLE IN THE REGULATION OF TRANSCRIPTION, AND POSSIBLE DEMETHYLATION MECHANISMS THAT MIGHT BE APPLICABLE IN OA. IN SUMMARY, MIRNA MAY HAVE IMPORTANT DIAGNOSTIC AND THERAPEUTIC POTENTIAL, AND MIGHT PROVIDE A NOVEL MEANS OF TREATING OA. 2011 12 5109 36 POLYPHENOL-RELATED EPIGENETIC MODIFICATIONS IN OSTEOARTHRITIS: CURRENT THERAPEUTIC PERSPECTIVES. THE HYALINE CARTILAGE IS AN AVASCULAR, ANEURAL AND ALYMPHATIC TISSUE WITH A LIMITED ABILITY TO REPAIR ITSELF. WHEN THE CARTILAGE IS EXPOSED TO SOME KIND OF INJURY, IT USUALLY TRIGGERS OSTEOARTHRITIS (OA), A PREVALENT AND DEGENERATIVE JOINT DISEASE CLOSELY RELATED TO AGING. OA IS BOTH COMPLEX AND MULTIFACTORIAL, AND IS THE MOST COMMON FORM OF ARTHRITIS, BEING POSITIONED AS A MAJOR CAUSE OF PAIN AND DYSFUNCTION IN THE WORLD. IN ADDITION, HIGH OA PREVALENCE CAN GREATLY AFFECT WORK CAPACITY, MAKING THIS DISEASE A SIGNIFICANT SOCIAL PROBLEM, THEREFORE, ITS PREVENTION AND TREATMENT BECOMES A PRIORITY. AT THIS TIME, THERE ARE NUMEROUS THERAPEUTIC STRATEGIES AVAILABLE TO IMPROVE HYALINE CARTILAGE REPAIR BY USING CHONDROCYTES OR MESENCHYMAL CELLS, BUT NEITHER IS EFFECTIVE ENOUGH TO GENERATE FUNCTIONAL AND DURABLE TISSUE REPARATION OVER TIME. IN OA, CHONDROCYTES HAVE AN ABERRANT GENE EXPRESSION AND PHENOTYPE, RESULTING IN A LOSS OF BALANCE BETWEEN ANABOLIC AND CATABOLIC PROCESSES. ENVIRONMENTAL INFLUENCES SUCH AS RADIATION, INFECTION, SMOKING, NUTRIENTS, TOXINS AND STRESS CAN AFFECT GENE EXPRESSION PATTERNS, WHICH MAY CONSTITUTE RISK FACTORS FOR VARIOUS CHRONIC AND DEGENERATIVE DISEASES, SUCH AS OA. IN ADDITION, CONSIDERABLE EVIDENCE SHOWS THAT EPIGENETIC MECHANISMS PLAY AN IMPORTANT ROLE IN OA CHONDROGENESIS AND PATHOGENESIS. NATURAL PLANT-DERIVED PRODUCTS SUCH AS POLYPHENOLS, WHICH ARE SECONDARY METABOLITES CONSIDERED TO HAVE POTENTIAL ACTIVITY TO BLOCK INFLAMMATION IN SEVERAL DEGENERATIVE DISEASES, CAN STIMULATE EPIGENETIC MODIFICATIONS, AND MAY PROVIDE NEW THERAPEUTIC TARGETS AND COST-EFFECTIVE TREATMENTS. THIS REVIEW AIMS TO PRESENT VARIOUS POLYPHENOLBASED THERAPIES CURRENTLY USED FOR THE TREATMENT OF SEVERAL PROGRESSIVE DISEASES, INCLUDING OA. 2016 13 797 32 CELLULAR SENESCENCE IN OSTEOARTHRITIS PATHOLOGY. CELLULAR SENESCENCE IS A STATE OF STABLE PROLIFERATION ARREST OF CELLS. THE SENESCENCE PATHWAY HAS MANY BENEFICIAL EFFECTS AND IS SEEN TO BE ACTIVATED IN DAMAGED/STRESSED CELLS, AS WELL AS DURING EMBRYONIC DEVELOPMENT AND WOUND HEALING. HOWEVER, THE PERSISTENCE AND ACCUMULATION OF SENESCENT CELLS IN VARIOUS TISSUES CAN ALSO IMPAIR FUNCTION AND HAVE BEEN IMPLICATED IN THE PATHOGENESIS OF MANY AGE-RELATED DISEASES. OSTEOARTHRITIS (OA), A SEVERELY DEBILITATING CHRONIC CONDITION CHARACTERIZED BY PROGRESSIVE TISSUE REMODELING AND LOSS OF JOINT FUNCTION, IS THE MOST PREVALENT DISEASE OF THE SYNOVIAL JOINTS, AND INCREASING AGE IS THE PRIMARY OA RISK FACTOR. THE PROFILE OF INFLAMMATORY AND CATABOLIC MEDIATORS PRESENT DURING THE PATHOGENESIS OF OA IS STRIKINGLY SIMILAR TO THE SECRETORY PROFILE OBSERVED IN 'CLASSICAL' SENESCENT CELLS. DURING OA, CHONDROCYTES (THE SOLE CELL TYPE PRESENT WITHIN ARTICULAR CARTILAGE) EXHIBIT INCREASED LEVELS OF VARIOUS SENESCENCE MARKERS, SUCH AS SENESCENCE-ASSOCIATED BETA-GALACTOSIDASE (SABETAGAL) ACTIVITY, TELOMERE ATTRITION, AND ACCUMULATION OF P16INK4A. THIS SUGGESTS THE HYPOTHESIS THAT SENESCENCE OF CELLS WITHIN JOINT TISSUES MAY PLAY A PATHOLOGICAL ROLE IN THE CAUSATION OF OA. IN THIS REVIEW, WE DISCUSS THE MECHANISMS BY WHICH SENESCENT CELLS MAY PREDISPOSE SYNOVIAL JOINTS TO THE DEVELOPMENT AND/OR PROGRESSION OF OA, AS WELL AS TOUCHING UPON VARIOUS EPIGENETIC ALTERATIONS ASSOCIATED WITH BOTH OA AND SENESCENCE. 2017 14 296 35 AGING, CELL SENESCENCE, THE PATHOGENESIS AND TARGETED THERAPIES OF OSTEOARTHRITIS. OSTEOARTHRITIS (OA) IS A CHRONIC, DEBILITATING JOINT DISEASE CHARACTERIZED BY PROGRESSIVE DESTRUCTION OF ARTICULAR CARTILAGE. FOR A LONG TIME, OA HAS BEEN CONSIDERED AS A DEGENERATIVE DISEASE, WHILE RECENT OBSERVATIONS INDICATE THE MECHANISMS RESPONSIBLE FOR THE PATHOGENESIS OF OA ARE MULTIFACETED. AGING IS A KEY FACTOR IN ITS DEVELOPMENT. CURRENT TREATMENTS ARE PALLIATIVE AND NO DISEASE MODIFYING ANTI-OSTEOARTHRITIS DRUGS (DMOADS) ARE AVAILABLE. IN ADDITION TO ARTICULAR CARTILAGE DEGRADATION, CELLULAR SENESCENCE, SYNOVIAL INFLAMMATION, AND EPIGENETIC ALTERATIONS MAY ALL HAVE A ROLE IN ITS FORMATION. ACCUMULATING DATA DEMONSTRATE A CLEAR RELATIONSHIP BETWEEN THE SENESCENCE OF ARTICULAR CHONDROCYTES AND OA FORMATION AND PROGRESSION. INHIBITION OF CELL SENESCENCE MAY HELP IDENTIFY NEW AGENTS WITH THE PROPERTIES OF DMOADS. SEVERAL ANTI-CELLULAR SENESCENCE STRATEGIES HAVE BEEN PROPOSED AND THESE INCLUDE SIRTUIN-ACTIVATING COMPOUNDS (STACS), SENOLYTICS, AND SENOMORPHICS DRUGS. THESE AGENTS MAY SELECTIVELY REMOVE SENESCENT CELLS OR AMELIORATE THEIR HARMFUL EFFECTS. THE RESULTS FROM PRECLINICAL EXPERIMENTS AND CLINICAL TRIALS ARE INSPIRING. HOWEVER, MORE STUDIES ARE WARRANTED TO CONFIRM THEIR EFFICACY, SAFETY PROFILES AND ADVERSE EFFECTS OF THESE AGENTS. 2021 15 3829 28 INVOLVEMENT OF EPIGENETICS IN OSTEOARTHRITIS. OSTEOARTHRITIS (OA) IS THE MOST PREVALENT CHRONIC AGE-RELATED ARTHRITIC DISEASE THAT MAINLY AFFECTS THE DIARTHRODIAL JOINTS. NEVERTHELESS, THERE IS NO TREATMENT CURRENTLY AVAILABLE THAT CAN EFFECTIVELY REDUCE SYMPTOMS OR SLOW DOWN OR STOP DISEASE PROGRESSION. THE LACK OF DISEASE-MODIFYING THERAPIES COULD BE EXPLAINED BY THE COMPLEX PATHOGENESIS OF OA, WHICH IS STILL NOT COMPLETELY UNDERSTOOD. INTERTWINED EPIGENETIC MECHANISMS SUCH AS DNA METHYLATION, HISTONE MODIFICATIONS, AND NONCODING RNAS (NCRNAS) HAVE BEEN INDICATED AS IMPORTANT CELLULAR TOOLS TO MAINTAIN TISSUE HOMEOSTASIS UPON ENVIRONMENTAL CHALLENGES. THE CURRENT REVIEW ILLUSTRATES THAT DYSFUNCTIONAL EPIGENETIC CONTROL MECHANISMS IN THE ARTICULAR CARTILAGE LIKELY PLAY AN IMPORTANT ROLE IN DRIVING OA PATHOPHYSIOLOGY. 2017 16 1258 31 CURRENT UNDERSTANDING OF OSTEOARTHRITIS PATHOGENESIS AND RELEVANT NEW APPROACHES. OSTEOARTHRITIS (OA) IS THE MOST COMMON DEGENERATIVE JOINT DISEASE THAT CAUSES PAINFUL SWELLING AND PERMANENT DAMAGE TO THE JOINTS IN THE BODY. THE MOLECULAR MECHANISMS OF OA ARE CURRENTLY UNKNOWN. OA IS A HETEROGENEOUS DISEASE THAT AFFECTS THE ENTIRE JOINT, AND MULTIPLE TISSUES ARE ALTERED DURING OA DEVELOPMENT. TO BETTER UNDERSTAND THE PATHOLOGICAL MECHANISMS OF OA, NEW APPROACHES, METHODS, AND TECHNIQUES NEED TO BE USED TO UNDERSTAND OA PATHOGENESIS. IN THIS REVIEW, WE FIRST FOCUS ON THE EPIGENETIC REGULATION OF OA, WITH A PARTICULAR FOCUS ON DNA METHYLATION, HISTONE MODIFICATION, AND MICRORNA REGULATION, FOLLOWED BY A SUMMARY OF SEVERAL KEY MEDIATORS IN OA-ASSOCIATED PAIN. WE THEN INTRODUCE SEVERAL INNOVATIVE TECHNIQUES THAT HAVE BEEN AND WILL CONTINUE TO BE USED IN THE FIELDS OF OA AND OA-ASSOCIATED PAIN, SUCH AS CRISPR, SCRNA SEQUENCING, AND LINEAGE TRACING. NEXT, WE DISCUSS THE TIMELY UPDATES CONCERNING CELL DEATH REGULATION IN OA PATHOLOGY, INCLUDING PYROPTOSIS, FERROPTOSIS, AND AUTOPHAGY, AS WELL AS THEIR INDIVIDUAL ROLES IN OA AND POTENTIAL MOLECULAR TARGETS IN TREATING OA. FINALLY, OUR REVIEW HIGHLIGHTS NEW DIRECTIONS ON THE ROLE OF THE SYNOVIAL LYMPHATIC SYSTEM IN OA. AN IMPROVED UNDERSTANDING OF OA PATHOGENESIS WILL AID IN THE DEVELOPMENT OF MORE SPECIFIC AND EFFECTIVE THERAPEUTIC INTERVENTIONS FOR OA. 2022 17 1547 31 DNA METHYLATION IN OSTEOARTHRITIS. OSTEOARTHRITIS (OA) IS A PREVALENT DISEASE OF ARTICULAR JOINTS AND PRIMARILY CHARACTERIZED BY DEGRADATION AND CALCIFICATION OF ARTICULAR CARTILAGE. PRESENTLY, NO EFFECTIVE TREATMENT OTHER THAN PAIN RELIEF EXISTS AND PATIENTS ULTIMATELY NEED TO UNDERGO REPLACEMENT SURGERY OF THE AFFECTED JOINT. DURING DISEASE PROGRESSION ARTICULAR CHONDROCYTES, THE SINGLE CELL TYPE PRESENT IN ARTICULAR CARTILAGE, SHOW ALTERED TRANSCRIPTIONAL PROFILES AND UNDERGO PHENOTYPIC CHANGES THAT RESEMBLE THE TERMINAL DIFFERENTIATION ROUTE APPARENT IN GROWTH PLATE CHONDROCYTES. HENCE, GIVEN ITS PROMINENT FUNCTION IN BOTH REGULATING GENE EXPRESSION AND MAINTAINING CELLULAR PHENOTYPES, DNA METHYLATION OF CPG DINUCLEOTIDES IS INTENSIVELY STUDIED IN THE CONTEXT OF OA. AN INCREASING NUMBER OF STUDIES HAVE BEEN PUBLISHED THAT EMPLOYED A TARGETED APPROACH ON GENES KNOWN TO PLAY A ROLE IN OA PATHOPHYSIOLOGY. AS OF SUCH, IT HAS BECOME CLEAR THAT OA RESPONSIVE DNA METHYLATION CHANGES SEEM TO MEDIATE DISEASE ASSOCIATED ABERRANT GENE EXPRESSION. FURTHERMORE, ESTABLISHED OA SUSCEPTIBILITY ALLELES SUCH AS GDF5 AND DIO2 APPEAR TO CONFER OA RISK VIA DNA METHYLATION AND RESPECTIVE PATHOPHYSIOLOGICAL EXPRESSION CHANGES. IN MORE RECENT YEARS, GENOME WIDE PROFILING OF DNA METHYLATION IN OA AFFECTED ARTICULAR CARTILAGE HAS EMERGED AS A POWERFUL TOOL TO ADDRESS THE EPIGENETIC CHANGES IN THEIR ENTIRETY, WHICH HAS RESULTED IN THE IDENTIFICATION OF PUTATIVE PATIENT SUBGROUPS AS WELL AS GENERIC OA ASSOCIATED PATHWAYS. 2015 18 4776 29 NUTRACEUTICAL ACTIVITY IN OSTEOARTHRITIS BIOLOGY: A FOCUS ON THE NUTRIGENOMIC ROLE. OSTEOARTHRITIS (OA) IS A DISEASE ASSOCIATED TO AGE OR CONDITIONS THAT PRECIPITATE AGING OF ARTICULAR CARTILAGE, A POST-MITOTIC TISSUE THAT REMAINS FUNCTIONAL UNTIL THE FAILURE OF MAJOR HOMEOSTATIC MECHANISMS. OA SEVERELY IMPACTS THE NATIONAL HEALTH SYSTEM COSTS AND PATIENTS' QUALITY OF LIFE BECAUSE OF PAIN AND DISABILITY. IT IS A WHOLE-JOINT DISEASE SUSTAINED BY INFLAMMATORY AND OXIDATIVE SIGNALING PATHWAYS AND MARKED EPIGENETIC CHANGES RESPONSIBLE FOR CATABOLISM OF THE CARTILAGE EXTRACELLULAR MATRIX. OA USUALLY PROGRESSES UNTIL ITS SEVERITY REQUIRES JOINT ARTHROPLASTY. TO DELAY THIS PROGRESSION AND TO IMPROVE SYMPTOMS, A WIDE RANGE OF NATURALLY DERIVED COMPOUNDS HAVE BEEN PROPOSED AND ARE SUMMARIZED IN THIS REVIEW. PRECLINICAL IN VITRO AND IN VIVO STUDIES HAVE PROVIDED PROOF OF PRINCIPLE THAT MANY OF THESE NUTRACEUTICALS ARE ABLE TO EXERT PLEIOTROPIC AND SYNERGISTIC EFFECTS AND EFFECTIVELY COUNTERACT OA PATHOGENESIS BY EXERTING BOTH ANTI-INFLAMMATORY AND ANTIOXIDANT ACTIVITIES AND BY TUNING MAJOR OA-RELATED SIGNALING PATHWAYS. THE LATTER ARE THE BASIS FOR THE NUTRIGENOMIC ROLE PLAYED BY SOME OF THESE COMPOUNDS, GIVEN THE MARKED CHANGES IN THE TRANSCRIPTOME, MIRNOME, AND METHYLOME. ONGOING AND FUTURE CLINICAL TRIALS WILL HOPEFULLY CONFIRM THE DISEASE-MODIFYING ABILITY OF THESE BIOACTIVE MOLECULES IN OA PATIENTS. 2020 19 5796 31 STAT3 PROMOTES A YOUTHFUL EPIGENETIC STATE IN ARTICULAR CHONDROCYTES. EPIGENETIC MECHANISMS GUIDING ARTICULAR CARTILAGE REGENERATION AND AGE-RELATED DISEASE SUCH AS OSTEOARTHRITIS (OA) ARE POORLY UNDERSTOOD. STAT3 IS A CRITICAL AGE-PATTERNED TRANSCRIPTION FACTOR HIGHLY ACTIVE IN FETAL AND OA CHONDROCYTES, BUT THE CONTEXT-SPECIFIC ROLE OF STAT3 IN REGULATING THE EPIGENOME OF CARTILAGE CELLS REMAIN ELUSIVE. IN THIS STUDY, DNA METHYLATION PROFILING WAS PERFORMED ACROSS HUMAN CHONDROCYTE ONTOGENY TO BUILD AN EPIGENETIC CLOCK AND ESTABLISH AN ASSOCIATION BETWEEN CPG METHYLATION AND HUMAN CHONDROCYTE AGE. EXPOSURE OF ADULT CHONDROCYTES TO A SMALL MOLECULE STAT3 AGONIST DECREASED DNA METHYLATION, WHILE GENETIC ABLATION OF STAT3 IN FETAL CHONDROCYTES INDUCED GLOBAL HYPERMETHYLATION. CUT&RUN ASSAY AND SUBSEQUENT TRANSCRIPTIONAL VALIDATION REVEALED DNA METHYLTRANSFERASE 3 BETA (DNMT3B) AS ONE OF THE PUTATIVE STAT3 TARGETS IN CHONDROCYTE DEVELOPMENT AND OA. FUNCTIONAL ASSESSMENT OF HUMAN OA CHONDROCYTES SHOWED THE ACQUISITION OF PROGENITOR-LIKE IMMATURE PHENOTYPE BY A SIGNIFICANT SUBSET OF CELLS. FINALLY, CONDITIONAL DELETION OF STAT3 IN CARTILAGE CELLS INCREASED DNMT3B EXPRESSION IN ARTICULAR CHONDROCYTES IN THE KNEE JOINT IN VIVO AND RESULTED IN A MORE PROMINENT OA PROGRESSION IN A POST-TRAUMATIC OA (PTOA) MOUSE MODEL INDUCED BY DESTABILIZATION OF THE MEDIAL MENISCUS (DMM). TAKEN TOGETHER THESE DATA REVEAL A NOVEL ROLE FOR STAT3 IN REGULATING DNA METHYLATION IN CARTILAGE DEVELOPMENT AND DISEASE. OUR FINDINGS ALSO SUGGEST THAT ELEVATED LEVELS OF ACTIVE STAT3 IN OA CHONDROCYTES MAY INDICATE AN INTRINSIC ATTEMPT OF THE TISSUE TO REGENERATE BY PROMOTING A PROGENITOR-LIKE PHENOTYPE. HOWEVER, IT IS LIKELY THAT CHRONIC ACTIVATION OF THIS PATHWAY, INDUCED BY IL-6 CYTOKINES, IS DETRIMENTAL AND LEADS TO TISSUE DEGENERATION. 2023 20 5724 30 SKELETAL MUSCLE WASTING AND ITS RELATIONSHIP WITH OSTEOARTHRITIS: A MINI-REVIEW OF MECHANISMS AND CURRENT INTERVENTIONS. PURPOSE OF REVIEW: OSTEOARTHRITIS (OA) IS A SUBSET OF JOINT DISORDERS RESULTING IN DEGENERATION OF SYNOVIAL JOINTS. THIS LEADS TO PAIN, DISABILITY AND LOSS OF INDEPENDENCE. KNEE AND HIP OA ARE EXTREMELY PREVALENT, AND THEIR OCCURRENCE INCREASES WITH AGEING. SIMILARLY, LOSS OF MUSCLE MASS AND FUNCTION, SARCOPENIA, OCCURS DURING AGEING. RECENT FINDINGS: LITTLE IS KNOWN ABOUT THE IMPACT OF MUSCLE WASTING ON OA PROGRESSION; NEVERTHELESS, IT HAS BEEN SUGGESTED THAT MUSCLE WASTING DIRECTLY AFFECTS THE STABILITY OF THE JOINTS AND LOSS OF MOBILITY LEADS TO GRADUAL DEGENERATION OF ARTICULAR CARTILAGE. THE MOLECULAR MECHANISMS UNDERLYING MUSCLE WASTING IN OA ARE NOT WELL UNDERSTOOD; HOWEVER, THESE ARE PROBABLY RELATED TO CHANGES IN GENE EXPRESSION, AS WELL AS EPIGENETIC MODIFICATIONS. IT IS BECOMING CLEAR THAT SKELETAL MUSCLE WASTING PLAYS AN IMPORTANT ROLE IN OA DEVELOPMENT AND/OR PROGRESSION. HERE, WE DISCUSS MECHANISMS, CURRENT INTERVENTIONS, SUCH AS EXERCISE, AND POTENTIALLY NOVEL APPROACHES, SUCH AS MODULATION OF MICRORNAS, AIMING AT AMELIORATING OA SYMPTOMS THROUGH MAINTAINING MUSCLE MASS AND FUNCTION. 2019