1 1175 125 CONTRIBUTIONS OF AGE-RELATED THYMIC INVOLUTION TO IMMUNOSENESCENCE AND INFLAMMAGING. IMMUNE SYSTEM AGING IS CHARACTERIZED BY THE PARADOX OF IMMUNOSENESCENCE (INSUFFICIENCY) AND INFLAMMAGING (OVER-REACTION), WHICH INCORPORATE TWO SIDES OF THE SAME COIN, RESULTING IN IMMUNE DISORDER. IMMUNOSENESCENCE REFERS TO DISRUPTION IN THE STRUCTURAL ARCHITECTURE OF IMMUNE ORGANS AND DYSFUNCTION IN IMMUNE RESPONSES, RESULTING FROM BOTH AGED INNATE AND ADAPTIVE IMMUNITY. INFLAMMAGING, DESCRIBED AS A CHRONIC, STERILE, SYSTEMIC INFLAMMATORY CONDITION ASSOCIATED WITH ADVANCED AGE, IS MAINLY ATTRIBUTED TO SOMATIC CELLULAR SENESCENCE-ASSOCIATED SECRETORY PHENOTYPE (SASP) AND AGE-RELATED AUTOIMMUNE PREDISPOSITION. HOWEVER, THE INABILITY TO REDUCE SENESCENT SOMATIC CELLS (SSCS), BECAUSE OF IMMUNOSENESCENCE, EXACERBATES INFLAMMAGING. AGE-RELATED ADAPTIVE IMMUNE SYSTEM DEVIATIONS, PARTICULARLY ALTERED T CELL FUNCTION, ARE DERIVED FROM AGE-RELATED THYMIC ATROPHY OR INVOLUTION, A HALLMARK OF THYMIC AGING. RECENTLY, THERE HAVE BEEN MAJOR DEVELOPMENTS IN UNDERSTANDING HOW AGE-RELATED THYMIC INVOLUTION CONTRIBUTES TO INFLAMMAGING AND IMMUNOSENESCENCE AT THE CELLULAR AND MOLECULAR LEVELS, INCLUDING GENETIC AND EPIGENETIC REGULATION, AS WELL AS DEVELOPMENTS OF MANY POTENTIAL REJUVENATION STRATEGIES. HEREIN, WE DISCUSS THE RESEARCH PROGRESS UNCOVERING HOW AGE-RELATED THYMIC INVOLUTION CONTRIBUTES TO IMMUNOSENESCENCE AND INFLAMMAGING, AS WELL AS THEIR INTERSECTION. WE ALSO DESCRIBE HOW T CELL ADAPTIVE IMMUNITY MEDIATES INFLAMMAGING AND PLAYS A CRUCIAL ROLE IN THE PROGRESSION OF AGE-RELATED NEUROLOGICAL AND CARDIOVASCULAR DISEASES, AS WELL AS CANCER. WE THEN BRIEFLY OUTLINE THE UNDERLYING CELLULAR AND MOLECULAR MECHANISMS OF AGE-RELATED THYMIC INVOLUTION, AND FINALLY SUMMARIZE POTENTIAL REJUVENATION STRATEGIES TO RESTORE AGED THYMIC FUNCTION. 2020 2 3183 42 HALLMARKS OF T CELL AGING. THE AGED ADAPTIVE IMMUNE SYSTEM IS CHARACTERIZED BY PROGRESSIVE DYSFUNCTION AS WELL AS INCREASED AUTOIMMUNITY. THIS DECLINE IS RESPONSIBLE FOR ELEVATED SUSCEPTIBILITY TO INFECTION AND CANCER, AS WELL AS DECREASED VACCINATION EFFICACY. RECENT EVIDENCE INDICATES THAT CD4(+) T CELL-INTRINSIC ALTERATINS CONTRIBUTE TO CHRONIC INFLAMMATION AND ARE SUFFICIENT TO ACCELERATE AN ORGANISM-WIDE AGING PHENOTYPE, SUPPORTING THE IDEA THAT T CELL AGING PLAYS A MAJOR ROLE IN BODY-WIDE DETERIORATION. IN THIS REVIEW, WE PROPOSE TEN MOLECULAR HALLMARKS TO REPRESENT COMMON DENOMINATORS OF T CELL AGING. THESE HALLMARKS ARE GROUPED INTO FOUR PRIMARY HALLMARKS (THYMIC INVOLUTION, MITOCHONDRIAL DYSFUNCTION, GENETIC AND EPIGENETIC ALTERATIONS, AND LOSS OF PROTEOSTASIS) AND FOUR SECONDARY HALLMARKS (REDUCTION OF THE TCR REPERTOIRE, NAIVE-MEMORY IMBALANCE, T CELL SENESCENCE, AND LACK OF EFFECTOR PLASTICITY), AND TOGETHER THEY EXPLAIN THE MANIFESTATION OF THE TWO INTEGRATIVE HALLMARKS (IMMUNODEFICIENCY AND INFLAMMAGING). A MAJOR CHALLENGE NOW IS WEIGHING THE RELATIVE IMPACT OF THESE HALLMARKS ON T CELL AGING AND UNDERSTANDING THEIR INTERCONNECTIONS, WITH THE FINAL GOAL OF DEFINING MOLECULAR TARGETS FOR INTERVENTIONS IN THE AGING PROCESS. 2021 3 3551 44 IMMUNOSENESCENCE: MOLECULAR MECHANISMS AND DISEASES. INFECTION SUSCEPTIBILITY, POOR VACCINATION EFFICACY, AGE-RELATED DISEASE ONSET, AND NEOPLASMS ARE LINKED TO INNATE AND ADAPTIVE IMMUNE DYSFUNCTION THAT ACCOMPANIES AGING (KNOWN AS IMMUNOSENESCENCE). DURING AGING, ORGANISMS TEND TO DEVELOP A CHARACTERISTIC INFLAMMATORY STATE THAT EXPRESSES HIGH LEVELS OF PRO-INFLAMMATORY MARKERS, TERMED INFLAMMAGING. THIS CHRONIC INFLAMMATION IS A TYPICAL PHENOMENON LINKED TO IMMUNOSENESCENCE AND IT IS CONSIDERED THE MAJOR RISK FACTOR FOR AGE-RELATED DISEASES. THYMIC INVOLUTION, NAIVE/MEMORY CELL RATIO IMBALANCE, DYSREGULATED METABOLISM, AND EPIGENETIC ALTERATIONS ARE STRIKING FEATURES OF IMMUNOSENESCENCE. DISTURBED T-CELL POOLS AND CHRONIC ANTIGEN STIMULATION MEDIATE PREMATURE SENESCENCE OF IMMUNE CELLS, AND SENESCENT IMMUNE CELLS DEVELOP A PROINFLAMMATORY SENESCENCE-ASSOCIATED SECRETORY PHENOTYPE THAT EXACERBATES INFLAMMAGING. ALTHOUGH THE UNDERLYING MOLECULAR MECHANISMS REMAIN TO BE ADDRESSED, IT IS WELL DOCUMENTED THAT SENESCENT T CELLS AND INFLAMMAGING MIGHT BE MAJOR DRIVING FORCES IN IMMUNOSENESCENCE. POTENTIAL COUNTERACTIVE MEASURES WILL BE DISCUSSED, INCLUDING INTERVENTION OF CELLULAR SENESCENCE AND METABOLIC-EPIGENETIC AXES TO MITIGATE IMMUNOSENESCENCE. IN RECENT YEARS, IMMUNOSENESCENCE HAS ATTRACTED INCREASING ATTENTION FOR ITS ROLE IN TUMOR DEVELOPMENT. AS A RESULT OF THE LIMITED PARTICIPATION OF ELDERLY PATIENTS, THE IMPACT OF IMMUNOSENESCENCE ON CANCER IMMUNOTHERAPY IS UNCLEAR. DESPITE SOME SURPRISING RESULTS FROM CLINICAL TRIALS AND DRUGS, IT IS NECESSARY TO INVESTIGATE THE ROLE OF IMMUNOSENESCENCE IN CANCER AND OTHER AGE-RELATED DISEASES. 2023 4 5543 42 ROLE OF ENDOGENOUS GLUCOCORTICOIDS IN CANCER IN THE ELDERLY. ALTHOUGH NOT A DISEASE ITSELF, AGING REPRESENTS A RISK FACTOR FOR MANY AGING-RELATED ILLNESSES, INCLUDING CANCER. NUMEROUS CAUSES UNDERLIE THE INCREASED INCIDENCE OF MALIGNANCIES IN THE ELDERLY, FOR EXAMPLE, GENOMIC INSTABILITY AND EPIGENETIC ALTERATIONS THAT OCCUR AT CELLULAR LEVEL, WHICH ALSO INVOLVE THE IMMUNE CELLS. THE PROGRESSIVE DECLINE OF THE IMMUNE SYSTEM FUNCTIONS THAT OCCURS IN AGING DEFINES IMMUNOSENESCENCE, AND INCLUDES BOTH INNATE AND ADAPTIVE IMMUNITY; THE LATTER UNDERGOES MAJOR ALTERATIONS. AGING AND CHRONIC STRESS SHARE THE ABNORMAL HYPOTHALAMIC(-)PITUITARY(-)ADRENAL AXIS ACTIVATION, WHERE ALTERED PERIPHERAL GLUCOCORTICOIDS (GC) LEVELS AND CHRONIC STRESS HAVE BEEN ASSOCIATED WITH ACCELERATED CELLULAR AGING, PREMATURE IMMUNOSENESCENCE, AND AGING-RELATED DISEASES. CONSEQUENTLY, CHANGES IN GC LEVELS AND SENSITIVITY CONTRIBUTE TO THE SIGNS OF IMMUNOSENESCENCE, NAMELY FEWER NAIVE T CELLS, POOR IMMUNE RESPONSE TO NEW ANTIGENS, DECREASED CELL-MEDIATED IMMUNITY, AND THYMIC INVOLUTION. GC SIGNALING ALTERATIONS ALSO INVOLVE EPIGENETIC ALTERATIONS IN DNA METHYLATION, WITH TRANSCRIPTION MODIFICATIONS THAT MAY CONTRIBUTE TO IMMUNOSENESCENCE. IMMUNE CELL AGING LEADS TO DECREASED LEVELS OF IMMUNOSURVEILLANCE, THEREBY PROVIDING TUMOR CELLS ONE MORE ROUTE FOR IMMUNE SYSTEM ESCAPE. HERE, THE CONTRIBUTION OF GC SECRETION AND SIGNALING DYSREGULATION TO THE INCREASED INCIDENCE OF TUMORIGENESIS IN THE ELDERLY IS REVIEWED. 2018 5 3181 24 HALLMARKS OF AGING: AN EXPANDING UNIVERSE. AGING IS DRIVEN BY HALLMARKS FULFILLING THE FOLLOWING THREE PREMISES: (1) THEIR AGE-ASSOCIATED MANIFESTATION, (2) THE ACCELERATION OF AGING BY EXPERIMENTALLY ACCENTUATING THEM, AND (3) THE OPPORTUNITY TO DECELERATE, STOP, OR REVERSE AGING BY THERAPEUTIC INTERVENTIONS ON THEM. WE PROPOSE THE FOLLOWING TWELVE HALLMARKS OF AGING: GENOMIC INSTABILITY, TELOMERE ATTRITION, EPIGENETIC ALTERATIONS, LOSS OF PROTEOSTASIS, DISABLED MACROAUTOPHAGY, DEREGULATED NUTRIENT-SENSING, MITOCHONDRIAL DYSFUNCTION, CELLULAR SENESCENCE, STEM CELL EXHAUSTION, ALTERED INTERCELLULAR COMMUNICATION, CHRONIC INFLAMMATION, AND DYSBIOSIS. THESE HALLMARKS ARE INTERCONNECTED AMONG EACH OTHER, AS WELL AS TO THE RECENTLY PROPOSED HALLMARKS OF HEALTH, WHICH INCLUDE ORGANIZATIONAL FEATURES OF SPATIAL COMPARTMENTALIZATION, MAINTENANCE OF HOMEOSTASIS, AND ADEQUATE RESPONSES TO STRESS. 2023 6 5632 36 SENESCENT CELLS: SASPECTED DRIVERS OF AGE-RELATED PATHOLOGIES. THE PROGRESSION OF PHYSIOLOGICAL AGEING IS DRIVEN BY INTRACELLULAR ABERRATIONS INCLUDING TELOMERE ATTRITION, GENOMIC INSTABILITY, EPIGENETIC ALTERATIONS AND LOSS OF PROTEOSTASIS. THESE IN TURN DAMAGE CELLS AND COMPROMISE THEIR FUNCTIONALITY. CELLULAR SENESCENCE, A STABLE IRREVERSIBLE CELL-CYCLE ARREST, IS ELICITED IN DAMAGED CELLS AND PREVENTS THEIR PROPAGATION IN THE ORGANISM. UNDER NORMAL CONDITIONS, SENESCENT CELLS RECRUIT THE IMMUNE SYSTEM WHICH FACILITATES THEIR REMOVAL FROM TISSUES. NEVERTHELESS, DURING AGEING, TISSUE-RESIDING SENESCENT CELLS TEND TO ACCUMULATE, AND MIGHT NEGATIVELY IMPACT THEIR MICROENVIRONMENT VIA PROFOUND SECRETORY PHENOTYPE WITH PRO-INFLAMMATORY CHARACTERISTICS, TERMED SENESCENCE-ASSOCIATED SECRETORY PHENOTYPE (SASP). INDEED, SENESCENT CELLS ARE MOSTLY ABUNDANT AT SITES OF AGE-RELATED PATHOLOGIES, INCLUDING DEGENERATIVE DISORDERS AND MALIGNANCIES. INTERESTINGLY, STUDIES ON PROGEROID MICE INDICATE THAT SELECTIVE ELIMINATION OF SENESCENT CELLS CAN DELAY AGE-RELATED DETERIORATION. THIS SUGGESTS THAT CHRONIC INFLAMMATION INDUCED BY SENESCENT CELLS MIGHT BE A MAIN DRIVER OF THESE PATHOLOGIES. IMPORTANTLY, SENESCENT CELLS ACCUMULATE AS A RESULT OF DEFICIENT IMMUNE SURVEILLANCE, AND THEIR REMOVAL IS INCREASED UPON THE USE OF IMMUNE STIMULATORY AGENTS. INSIGHTS INTO MECHANISMS OF SENESCENCE SURVEILLANCE COULD BE COMBINED WITH CURRENT APPROACHES FOR CANCER IMMUNOTHERAPY TO PROPOSE NEW PREVENTIVE AND THERAPEUTIC STRATEGIES FOR AGE-RELATED DISEASES. 2014 7 929 27 CHRONIC INFLAMMATION: ACCELERATOR OF BIOLOGICAL AGING. BIOLOGICAL AGING IS CHARACTERIZED BY A CHRONIC LOW-GRADE INFLAMMATION LEVEL. THIS CHRONIC PHENOMENON HAS BEEN NAMED "INFLAMM-AGING" AND IS A HIGHLY SIGNIFICANT RISK FACTOR FOR MORBIDITY AND MORTALITY IN THE OLDER PERSONS. THE MOST COMMON THEORIES OF INFLAMM-AGING INCLUDE REDOX STRESS, MITOCHONDRIAL DYSFUNCTION, GLYCATION, DEREGULATION OF THE IMMUNE SYSTEM, HORMONAL CHANGES, EPIGENETIC MODIFICATIONS, AND DYSFUNCTION TELOMERE ATTRITION. INFLAMM-AGING PLAYS A ROLE IN THE INITIATION AND PROGRESSION OF AGE-RELATED DISEASES SUCH AS TYPE II DIABETES, ALZHEIMER'S DISEASE, CARDIOVASCULAR DISEASE, FRAILTY, SARCOPENIA, OSTEOPOROSIS, AND CANCER. THIS REVIEW WILL COVER THE IDENTIFICATION OF PATHWAYS THAT CONTROL AGE-RELATED INFLAMMATION ACROSS MULTIPLE SYSTEMS AND ITS POTENTIAL CAUSAL ROLE IN CONTRIBUTING TO ADVERSE HEALTH OUTCOMES. 2017 8 5919 27 TARGETING CELLULAR SENESCENCE FOR AGE-RELATED DISEASES: PATH TO CLINICAL TRANSLATION. BEYOND THE PALLIATIVE REACH OF TODAY'S MEDICINES, MEDICAL THERAPIES OF TOMORROW AIM TO TREAT THE ROOT CAUSE OF AGE-RELATED DISEASES BY TARGETING FUNDAMENTAL AGING MECHANISMS. PILLARS OF AGING INCLUDE, AMONG OTHERS, GENOMIC INSTABILITY, TELOMERE ATTRITION, EPIGENETIC ALTERATIONS, LOSS OF PROTEOSTASIS, DYSREGULATED NUTRIENT SENSING, MITOCHONDRIAL DYSFUNCTION, CELLULAR SENESCENCE, STEM CELL EXHAUSTION, AND ALTERED INTERCELLULAR COMMUNICATION. THE UNITARY THEORY OF FUNDAMENTAL AGING PROCESSES POSITS THAT BY TARGETING ONE FUNDAMENTAL AGING PROCESS, IT MAY BE FEASIBLE TO IMPACT SEVERAL OR ALL OTHERS GIVEN ITS INTERDEPENDENCE. INDEED, PATHOLOGIC ACCUMULATION OF SENESCENT CELLS IS IMPLICATED IN CHRONIC DISEASES AND AGE-ASSOCIATED MORBIDITIES, SUGGESTING THAT SENESCENT CELLS ARE A GOOD TARGET FOR WHOLE-BODY AGING INTERVENTION. PRECLINICAL STUDIES USING SENOLYTICS, AGENTS THAT SELECTIVELY ELIMINATE SENESCENT CELLS, AND SENOMORPHICS, AGENTS THAT INHIBIT PRODUCTION OR RELEASE OF SENESCENCE-ASSOCIATED SECRETORY PHENOTYPE FACTORS, SHOW PROMISE IN SEVERAL AGING AND DISEASE PRECLINICAL MODELS. EARLY CLINICAL TRIALS USING A SENOLYTIC COMBINATION (DASATINIB AND QUERCETIN), AND OTHER SENOLYTICS INCLUDING FLAVONOID, FISETIN, AND BCL-XL INHIBITORS, ILLUSTRATE THE POTENTIAL OF SENOLYTICS TO ALLEVIATE AGE-RELATED DYSFUNCTION AND DISEASES INCLUDING WOUND HEALING. TRANSLATION INTO CLINICAL APPLICATIONS REQUIRES PARALLEL CLINICAL TRIALS ACROSS INSTITUTIONS TO VALIDATE SENOTHERAPEUTICS AS A VANGUARD FOR DELAYING, PREVENTING, OR TREATING AGE-RELATED DISORDERS AND AESTHETIC AGING. 2022 9 5140 36 POTENTIAL REGULATORS OF THE SENESCENCE-ASSOCIATED SECRETORY PHENOTYPE DURING SENESCENCE AND AGING. SENESCENT CELLS EXPRESS AND SECRETE A VARIETY OF EXTRACELLULAR MODULATORS THAT INCLUDE CYTOKINES, CHEMOKINES, PROTEASES, GROWTH FACTORS, AND SOME ENZYMES ASSOCIATED WITH EXTRACELLULAR MATRIX REMODELING, DEFINED AS THE SENESCENCE-ASSOCIATED SECRETORY PHENOTYPE (SASP). SASP REINFORCES SENESCENT CELL CYCLE ARREST, STIMULATES AND RECRUITS IMMUNE CELLS FOR IMMUNE-MEDIATED CLEARANCE OF POTENTIALLY TUMORIGENIC CELLS, LIMITS OR INDUCES FIBROSIS, AND PROMOTES WOUND HEALING AND TISSUE REGENERATION. ON THE OTHER HAND, SASP MEDIATES CHRONIC INFLAMMATION LEADING TO THE DESTRUCTION OF TISSUE STRUCTURE AND FUNCTION AND STIMULATING THE GROWTH AND SURVIVAL OF TUMOR CELLS. SASP IS HIGHLY HETEROGENEOUS AND THE ROLE OF SASP DEPENDS ON THE CONTEXT. THE REGULATION OF SASP OCCURS AT MULTIPLE LEVELS INCLUDING CHROMATIN REMODELING, TRANSCRIPTION, MRNA TRANSLATION, INTRACELLULAR TRAFFICKING, AND SECRETION. SEVERAL SASP MODULATORS HAVE ALREADY BEEN IDENTIFIED SETTING THE STAGE FOR FUTURE RESEARCH ON THEIR CLINICAL APPLICATIONS. IN THIS REVIEW, WE SUMMARIZE IN DETAIL THE POTENTIAL SIGNALING PATHWAYS THAT TRIGGER AND REGULATE SASP PRODUCTION DURING AGING AND SENESCENCE. 2022 10 3596 41 IMPLICATIONS OF SPHINGOLIPIDS ON AGING AND AGE-RELATED DISEASES. AGING IS A PROCESS LEADING TO A PROGRESSIVE LOSS OF PHYSIOLOGICAL INTEGRITY AND HOMEOSTASIS, AND A PRIMARY RISK FACTOR FOR MANY LATE-ONSET CHRONIC DISEASES. THE MECHANISMS UNDERLYING AGING HAVE LONG PIQUED THE CURIOSITY OF SCIENTISTS. HOWEVER, THE IDEA THAT AGING IS A BIOLOGICAL PROCESS SUSCEPTIBLE TO GENETIC MANIPULATION WAS NOT WELL ESTABLISHED UNTIL THE DISCOVERY THAT THE INHIBITION OF INSULIN/IGF-1 SIGNALING EXTENDED THE LIFESPAN OF C. ELEGANS. ALTHOUGH AGING IS A COMPLEX MULTISYSTEM PROCESS, LOPEZ-OTIN ET AL. DESCRIBED AGING IN REFERENCE TO NINE HALLMARKS OF AGING. THESE NINE HALLMARKS INCLUDE: GENOMIC INSTABILITY, TELOMERE ATTRITION, EPIGENETIC ALTERATIONS, LOSS OF PROTEOSTASIS, DEREGULATED NUTRIENT SENSING, MITOCHONDRIAL DYSFUNCTION, CELLULAR SENESCENCE, STEM CELL EXHAUSTION, AND ALTERED INTERCELLULAR COMMUNICATION. DUE TO RECENT ADVANCES IN LIPIDOMIC, INVESTIGATION INTO THE ROLE OF LIPIDS IN BIOLOGICAL AGING HAS INTENSIFIED, PARTICULARLY THE ROLE OF SPHINGOLIPIDS (SL). SLS ARE A DIVERSE GROUP OF LIPIDS ORIGINATING FROM THE ENDOPLASMIC RETICULUM (ER) AND CAN BE MODIFIED TO CREATE A VASTLY DIVERSE GROUP OF BIOACTIVE METABOLITES THAT REGULATE ALMOST EVERY MAJOR CELLULAR PROCESS, INCLUDING CELL CYCLE REGULATION, SENESCENCE, PROLIFERATION, AND APOPTOSIS. ALTHOUGH SL BIOLOGY REACHES ALL NINE HALLMARKS OF AGING, ITS CONTRIBUTION TO EACH HALLMARK IS DISPROPORTIONATE. IN THIS REVIEW, WE WILL DISCUSS IN DETAIL THE MAJOR CONTRIBUTIONS OF SLS TO THE HALLMARKS OF AGING AND AGE-RELATED DISEASES WHILE ALSO SUMMARIZING THE IMPORTANCE OF THEIR OTHER MINOR BUT INTEGRAL CONTRIBUTIONS. 2021 11 798 34 CELLULAR SENESCENCE, SENESCENCE-ASSOCIATED SECRETORY PHENOTYPE, AND CHRONIC KIDNEY DISEASE. CHRONIC KIDNEY DISEASE (CKD) IS INCREASINGLY BEING ACCEPTED AS A TYPE OF RENAL AGEING. THE KIDNEY UNDERGOES AGE-RELATED ALTERATIONS IN BOTH STRUCTURE AND FUNCTION. TO DATE, A COMPREHENSIVE ANALYSIS OF CELLULAR SENESCENCE AND SENESCENCE-ASSOCIATED SECRETORY PHENOTYPE (SASP) IN CKD IS LACKING. HENCE, THIS REVIEW MAINLY DISCUSSES THE RELATIONSHIP BETWEEN THE TWO PHENOMENA TO SHOW THE STRIKING SIMILARITIES BETWEEN SASP AND CKD-ASSOCIATED SECRETORY PHENOTYPE (CASP). IT HAS BEEN REPORTED THAT REPLICATIVE SENESCENCE, STRESS-INDUCED PREMATURE AGEING, AND EPIGENETIC ABNORMALITIES PARTICIPATE IN THE OCCURRENCE AND DEVELOPMENT OF CKD. GENOMIC DAMAGE AND EXTERNAL ENVIRONMENTAL STIMULI CAUSE INCREASED LEVELS OF OXIDATIVE STRESS AND A CHRONIC INFLAMMATORY STATE AS A RESULT OF IRREVERSIBLE CELL CYCLE ARREST AND LOW DOSES OF SASP. SIMILAR TO SASP, CASP FACTORS ACTIVATE TISSUE REPAIR BY MULTIPLE MECHANISMS. ONCE TISSUE REPAIR FAILS, THE ACCUMULATED SASP OR CASP SPECIES AGGRAVATE DNA DAMAGE RESPONSE (DDR) AND CAUSE THE SENESCENT CELLS TO SECRETE MORE SASP FACTORS, ACCELERATING THE PROCESS OF CELLULAR AGEING AND EVENTUALLY LEADING TO VARIOUS AGEING-RELATED CHANGES. IT IS CONCLUDED THAT CELLULAR SENESCENCE AND SASP PARTICIPATE IN THE PATHOLOGICAL PROCESS OF CKD, AND CORRESPONDINGLY CKD ACCELERATED THE PROGRESSION OF CELL SENESCENCE AND THE SECRETION OF SASP. THESE RESULTS WILL FACILITATE THE INTEGRATION OF THESE MECHANISMS INTO THE CARE AND MANAGEMENT OF CKD AND OTHER AGE-RELATED DISEASES. 2017 12 6189 32 THE IMPACT OF LIFE STRESS ON HALLMARKS OF AGING AND ACCELERATED SENESCENCE: CONNECTIONS IN SICKNESS AND IN HEALTH. CHRONIC STRESS IS A RISK FACTOR FOR NUMEROUS AGING-RELATED DISEASES AND HAS BEEN SHOWN TO SHORTEN LIFESPAN IN HUMANS AND OTHER SOCIAL MAMMALS. YET HOW LIFE STRESS CAUSES SUCH A VAST RANGE OF DISEASES IS STILL LARGELY UNCLEAR. IN RECENT YEARS, THE IMPACT OF STRESS ON HEALTH AND AGING HAS BEEN INCREASINGLY ASSOCIATED WITH THE DYSREGULATION OF THE SO-CALLED HALLMARKS OF AGING. THESE ARE BASIC BIOLOGICAL MECHANISMS THAT INFLUENCE INTRINSIC CELLULAR FUNCTIONS AND WHOSE ALTERATION CAN LEAD TO ACCELERATED AGING. HERE, WE REVIEW CORRELATIONAL AND EXPERIMENTAL LITERATURE (PRIMARILY FOCUSING ON EVIDENCE FROM HUMANS AND MURINE MODELS) ON THE CONTRIBUTION OF LIFE STRESS - PARTICULARLY STRESS DERIVED FROM ADVERSE SOCIAL ENVIRONMENTS - TO TRIGGER HALLMARKS OF AGING, INCLUDING CELLULAR SENESCENCE, STERILE INFLAMMATION, TELOMERE SHORTENING, PRODUCTION OF REACTIVE OXYGEN SPECIES, DNA DAMAGE, AND EPIGENETIC CHANGES. WE ALSO EVALUATE THE VALIDITY OF STRESS-INDUCED SENESCENCE AND ACCELERATED AGING AS AN ETIOPATHOLOGICAL PROPOSITION. FINALLY, WE HIGHLIGHT CURRENT GAPS OF KNOWLEDGE AND FUTURE DIRECTIONS FOR THE FIELD, AND DISCUSS PERSPECTIVES FOR TRANSLATIONAL GEROSCIENCE. 2023 13 4379 35 MITOCHONDRIAL DYSFUNCTION AND AGING: INSIGHTS FROM THE ANALYSIS OF EXTRACELLULAR VESICLES. THE PROGRESSIVE DECLINE OF CELL FUNCTION AND INTEGRITY, MANIFESTING CLINICALLY AS INCREASED VULNERABILITY TO ADVERSE OUTCOMES AND DEATH, IS CORE TO BIOLOGICAL AGING. MITOCHONDRIAL DYSFUNCTION, OXIDATIVE STRESS, ALTERED INTERCELLULAR COMMUNICATION (INCLUDING CHRONIC LOW-GRADE INFLAMMATION), GENOMIC INSTABILITY, TELOMERE ATTRITION, LOSS OF PROTEOSTASIS, ALTERED NUTRIENT SENSING, EPIGENETIC ALTERATIONS, AND STEM CELL EXHAUSTION HAVE BEEN PROPOSED AS HALLMARKS OF AGING. THESE "AGING PILLARS" ARE NOT MUTUALLY EXCLUSIVE, MAKING THE MATTER INTRICATE AND LEAVING NUMEROUS UNANSWERED QUESTIONS. THE CHARACTERIZATION OF CIRCULATING EXTRACELLULAR VESICLES (EVS) HAS RECENTLY ALLOWED SPECIFIC SECRETORY PHENOTYPES ASSOCIATED WITH AGING TO BE IDENTIFIED. AS SUCH, EVS MAY SERVE AS NOVEL BIOMARKERS FOR CAPTURING THE COMPLEXITY OF AGING. BESIDES THE MITOCHONDRIAL(-)LYSOSOMAL AXIS, EV TRAFFICKING HAS BEEN PROPOSED AS AN ADDITIONAL LAYER IN MITOCHONDRIAL QUALITY CONTROL. INDEED, DISRUPTION OF THE MITOCHONDRIAL(-)LYSOSOMAL AXIS COUPLED WITH ABNORMAL EV SECRETION MAY PLAY A ROLE IN THE PATHOGENESIS OF AGING AND SEVERAL DISEASE CONDITIONS. HERE, WE DISCUSS (1) THE MECHANISMS OF EV GENERATION; (2) THE RELATIONSHIP BETWEEN THE MITOCHONDRIAL(-)LYSOSOMAL AXIS AND EV TRAFFICKING IN THE SETTING OF MITOCHONDRIAL QUALITY CONTROL; AND (3) THE PROSPECT OF USING EVS AS AGING BIOMARKERS AND AS DELIVERY SYSTEMS FOR THERAPEUTICS AGAINST AGE-RELATED CONDITIONS. 2019 14 285 33 AGING AND AGING-RELATED DISEASES: FROM MOLECULAR MECHANISMS TO INTERVENTIONS AND TREATMENTS. AGING IS A GRADUAL AND IRREVERSIBLE PATHOPHYSIOLOGICAL PROCESS. IT PRESENTS WITH DECLINES IN TISSUE AND CELL FUNCTIONS AND SIGNIFICANT INCREASES IN THE RISKS OF VARIOUS AGING-RELATED DISEASES, INCLUDING NEURODEGENERATIVE DISEASES, CARDIOVASCULAR DISEASES, METABOLIC DISEASES, MUSCULOSKELETAL DISEASES, AND IMMUNE SYSTEM DISEASES. ALTHOUGH THE DEVELOPMENT OF MODERN MEDICINE HAS PROMOTED HUMAN HEALTH AND GREATLY EXTENDED LIFE EXPECTANCY, WITH THE AGING OF SOCIETY, A VARIETY OF CHRONIC DISEASES HAVE GRADUALLY BECOME THE MOST IMPORTANT CAUSES OF DISABILITY AND DEATH IN ELDERLY INDIVIDUALS. CURRENT RESEARCH ON AGING FOCUSES ON ELUCIDATING HOW VARIOUS ENDOGENOUS AND EXOGENOUS STRESSES (SUCH AS GENOMIC INSTABILITY, TELOMERE DYSFUNCTION, EPIGENETIC ALTERATIONS, LOSS OF PROTEOSTASIS, COMPROMISE OF AUTOPHAGY, MITOCHONDRIAL DYSFUNCTION, CELLULAR SENESCENCE, STEM CELL EXHAUSTION, ALTERED INTERCELLULAR COMMUNICATION, DEREGULATED NUTRIENT SENSING) PARTICIPATE IN THE REGULATION OF AGING. FURTHERMORE, THOROUGH RESEARCH ON THE PATHOGENESIS OF AGING TO IDENTIFY INTERVENTIONS THAT PROMOTE HEALTH AND LONGEVITY (SUCH AS CALORIC RESTRICTION, MICROBIOTA TRANSPLANTATION, AND NUTRITIONAL INTERVENTION) AND CLINICAL TREATMENT METHODS FOR AGING-RELATED DISEASES (DEPLETION OF SENESCENT CELLS, STEM CELL THERAPY, ANTIOXIDATIVE AND ANTI-INFLAMMATORY TREATMENTS, AND HORMONE REPLACEMENT THERAPY) COULD DECREASE THE INCIDENCE AND DEVELOPMENT OF AGING-RELATED DISEASES AND IN TURN PROMOTE HEALTHY AGING AND LONGEVITY. 2022 15 2644 44 EPIGENOMIC DRIVERS OF IMMUNE DYSFUNCTION IN AGING. AGING INEVITABLY LEADS TO REDUCED IMMUNE FUNCTION, LEAVING THE ELDERLY MORE SUSCEPTIBLE TO INFECTIONS, LESS ABLE TO RESPOND TO PATHOGEN CHALLENGES, AND LESS RESPONSIVE TO PREVENTATIVE VACCINATIONS. NO CELL TYPE IS EXEMPT FROM THE RAVAGES OF AGE, AND EXTENSIVE STUDIES HAVE FOUND AGE-RELATED ALTERATIONS IN THE FREQUENCIES AND FUNCTIONS OF BOTH STEM AND PROGENITOR CELLS, AS WELL AS EFFECTOR CELLS OF BOTH THE INNATE AND ADAPTIVE IMMUNE SYSTEMS. THE INTRINSIC FUNCTIONAL REDUCTION IN IMMUNE COMPETENCE IS ALSO ASSOCIATED WITH LOW-GRADE CHRONIC INFLAMMATION, TERMED "INFLAMM-AGING," WHICH FURTHER PERPETUATES IMMUNE DYSFUNCTION. WHILE MANY OF THESE AGE-RELATED CELLULAR CHANGES ARE WELL CHARACTERIZED, UNDERSTANDING THE MOLECULAR CHANGES THAT UNDERPIN THE FUNCTIONAL DECLINE HAS PROVEN MORE DIFFICULT. CHANGES IN CHROMATIN ARE INCREASINGLY APPRECIATED AS A CAUSATIVE MECHANISM OF CELLULAR AND ORGANISMAL AGING ACROSS SPECIES. THESE CHANGES INCLUDE INCREASED GENOMIC INSTABILITY THROUGH LOSS OF HETEROCHROMATIN AND INCREASED DNA DAMAGE, TELOMERE ATTRITION, AND EPIGENETIC ALTERATIONS. IN THIS REVIEW, WE DISCUSS THE CONNECTIONS BETWEEN CHROMATIN, IMMUNOCOMPETENCE, AND THE LOSS OF FUNCTION ASSOCIATED WITH MAMMALIAN IMMUNE AGING. THROUGH UNDERSTANDING THE MOLECULAR EVENTS WHICH UNDERPIN THE PHENOTYPIC CHANGES OBSERVED IN THE AGED IMMUNE SYSTEM, IT IS HOPED THAT THE AGED IMMUNE SYSTEM CAN BE RESTORED TO PROVIDE YOUTHFUL IMMUNITY ONCE MORE. 2019 16 5432 31 REJUVENATION OF MESENCHYMAL STEM CELLS TO AMELIORATE SKELETAL AGING. ADVANCED AGE IS A SHARED RISK FACTOR FOR MANY CHRONIC AND DEBILITATING SKELETAL DISEASES INCLUDING OSTEOPOROSIS AND PERIODONTITIS. MESENCHYMAL STEM CELLS DEVELOP VARIOUS AGING PHENOTYPES INCLUDING THE ONSET OF SENESCENCE, INTRINSIC LOSS OF REGENERATIVE POTENTIAL AND EXACERBATION OF INFLAMMATORY MICROENVIRONMENT VIA SECRETORY FACTORS. THIS REVIEW ELABORATES ON THE EMERGING CONCEPTS ON THE MOLECULAR AND EPIGENETIC MECHANISMS OF MSC SENESCENCE, SUCH AS THE ACCUMULATION OF OXIDATIVE STRESS, DNA DAMAGE AND MITOCHONDRIAL DYSFUNCTION. SENESCENT MSCS AGGRAVATE LOCAL INFLAMMATION, DISRUPT BONE REMODELING AND BONE-FAT BALANCE, THEREBY CONTRIBUTING TO THE PROGRESSION OF AGE-RELATED BONE DISEASES. VARIOUS REJUVENATION STRATEGIES TO TARGET SENESCENT MSCS COULD PRESENT A PROMISING PARADIGM TO RESTORE SKELETAL AGING. 2023 17 293 38 AGING HALLMARKS AND THE ROLE OF OXIDATIVE STRESS. AGING IS A COMPLEX BIOLOGICAL PROCESS ACCOMPANIED BY A PROGRESSIVE DECLINE IN THE PHYSICAL FUNCTION OF THE ORGANISM AND AN INCREASED RISK OF AGE-RELATED CHRONIC DISEASES SUCH AS CARDIOVASCULAR DISEASES, CANCER, AND NEURODEGENERATIVE DISEASES. STUDIES HAVE ESTABLISHED THAT THERE EXIST NINE HALLMARKS OF THE AGING PROCESS, INCLUDING (I) TELOMERE SHORTENING, (II) GENOMIC INSTABILITY, (III) EPIGENETIC MODIFICATIONS, (IV) MITOCHONDRIAL DYSFUNCTION, (V) LOSS OF PROTEOSTASIS, (VI) DYSREGULATED NUTRIENT SENSING, (VII) STEM CELL EXHAUSTION, (VIII) CELLULAR SENESCENCE, AND (IX) ALTERED CELLULAR COMMUNICATION. ALL THESE ALTERATIONS HAVE BEEN LINKED TO SUSTAINED SYSTEMIC INFLAMMATION, AND THESE MECHANISMS CONTRIBUTE TO THE AGING PROCESS IN TIMING NOT CLEARLY DETERMINED YET. NEVERTHELESS, MITOCHONDRIAL DYSFUNCTION IS ONE OF THE MOST IMPORTANT MECHANISMS CONTRIBUTING TO THE AGING PROCESS. MITOCHONDRIA IS THE PRIMARY ENDOGENOUS SOURCE OF REACTIVE OXYGEN SPECIES (ROS). DURING THE AGING PROCESS, THERE IS A DECLINE IN ATP PRODUCTION AND ELEVATED ROS PRODUCTION TOGETHER WITH A DECLINE IN THE ANTIOXIDANT DEFENSE. ELEVATED ROS LEVELS CAN CAUSE OXIDATIVE STRESS AND SEVERE DAMAGE TO THE CELL, ORGANELLE MEMBRANES, DNA, LIPIDS, AND PROTEINS. THIS DAMAGE CONTRIBUTES TO THE AGING PHENOTYPE. IN THIS REVIEW, WE SUMMARIZE RECENT ADVANCES IN THE MECHANISMS OF AGING WITH AN EMPHASIS ON MITOCHONDRIAL DYSFUNCTION AND ROS PRODUCTION. 2023 18 3539 32 IMMUNE SENESCENCE, EPIGENETICS AND AUTOIMMUNITY. AGING OF THE IMMUNE SYSTEM IN HUMANS AND ANIMALS IS CHARACTERIZED BY A DECLINE IN BOTH ADAPTIVE AND INNATE IMMUNE RESPONSES. PARADOXICALLY, AGING IS ALSO ASSOCIATED WITH A STATE OF CHRONIC INFLAMMATION ("INFLAMMAGING") AND AN INCREASED LIKELIHOOD OF DEVELOPING AUTOIMMUNE DISEASES. EPIGENETIC CHANGES IN NON-DIVIDING AND DIVIDING CELLS, INCLUDING IMMUNE CELLS, DUE TO ENVIRONMENTAL FACTORS CONTRIBUTE TO THE INFLAMMATION AND AUTOIMMUNITY THAT CHARACTERIZE BOTH THE STATE AND DISEASES OF AGING. HERE, WE REVIEW THE EPIGENETIC MECHANISMS INVOLVED IN THE DEVELOPMENT OF IMMUNE SENESCENCE AND AUTOIMMUNITY IN OLD AGE. 2018 19 182 26 ACCELERATED LUNG AGING AND CHRONIC OBSTRUCTIVE PULMONARY DISEASE. THE PREVALENCE OF CHRONIC OBSTRUCTIVE PULMONARY DISEASE (COPD) INCREASES EXPONENTIALLY WITH AGING. ITS PATHOGENESIS, HOWEVER, IS NOT WELL KNOWN AND ASIDE FROM SMOKING CESSATION, THERE ARE NO DISEASE-MODIFYING TREATMENTS FOR THIS DISEASE. AREAS COVERED: COPD IS ASSOCIATED WITH ACCELERATING AGING AND AGING-RELATED DISEASES. IN THIS REVIEW, WE WILL DISCUSS THE HALLMARKS OF AGING INCLUDING GENOMIC INSTABILITY, TELOMERE ATTRITION, EPIGENETIC ALTERATION, LOSS OF PROTEOSTASIS, MITOCHONDRIAL DYSFUNCTION, DEREGULATED NUTRIENT SENSING, CELLULAR SENESCENCE, STEM CELL EXHAUSTION, AND ALTERED INTERCELLULAR COMMUNICATION, WHICH MAY BE INVOLVED IN COPD PATHOGENESIS. EXPERT COMMENTARY: COPD AND THE AGING PROCESS SHARE SIMILAR MOLECULAR AND CELLULAR CHANGES. AGING-RELATED MOLECULAR PATHWAYS MAY REPRESENT NOVEL THERAPEUTIC TARGETS AND BIOMARKERS FOR COPD. 2019 20 1387 38 DIABETIC GUT MICROBIOTA DYSBIOSIS AS AN INFLAMMAGING AND IMMUNOSENESCENCE CONDITION THAT FOSTERS PROGRESSION OF RETINOPATHY AND NEPHROPATHY. THE INCREASED PREVALENCE OF TYPE 2 DIABETES MELLITUS (T2DM) AND LIFE EXPECTANCY OF DIABETIC PATIENTS FOSTERS THE WORLDWIDE PREVALENCE OF RETINOPATHY AND NEPHROPATHY, TWO MAJOR MICROVASCULAR COMPLICATIONS THAT HAVE BEEN DIFFICULT TO TREAT WITH CONTEMPORARY GLUCOSE-LOWERING MEDICATIONS. THE GUT MICROBIOTA (GM) HAS BECOME A LIVELY FIELD RESEARCH IN THE LAST YEARS; THERE IS A GROWING RECOGNITION THAT ALTERED INTESTINAL MICROBIOTA COMPOSITION AND FUNCTION CAN DIRECTLY IMPACT THE PHENOMENON OF AGEING AND AGE-RELATED DISORDERS. IN FACT, HUMAN GM, ENVISAGED AS A POTENTIAL SOURCE OF NOVEL THERAPEUTICS, STRONGLY MODULATES HOST IMMUNITY AND METABOLISM. IT IS NOW CLEAR THAT GUT DYSBIOSIS AND THEIR PRODUCTS (E.G. P-CRESYL SULFATE, TRIMETHYLAMINE?N?OXIDE) DICTATE A SECRETORY ASSOCIATED SENESCENCE PHENOTYPE AND CHRONIC LOW-GRADE INFLAMMATION, FEATURES SHARED IN THE PHYSIOLOGICAL PROCESS OF AGEING ("INFLAMMAGING") AS WELL AS IN T2DM ("METAFLAMMATION") AND IN ITS MICROVASCULAR COMPLICATIONS. THIS REVIEW PROVIDES AN IN-DEPTH LOOK ON THE CROSSTALK BETWEEN GM, HOST IMMUNITY AND METABOLISM. FURTHER, IT CHARACTERIZES HUMAN GM SIGNATURES OF ELDERLY AND T2DM PATIENTS. FINALLY, A COMPREHENSIVE SCRUTINY OF RECENT MOLECULAR FINDINGS (E.G. EPIGENETIC CHANGES) UNDERLYING CAUSAL RELATIONSHIPS BETWEEN GM DYSBIOSIS AND DIABETIC RETINOPATHY/NEPHROPATHY COMPLICATIONS IS PINPOINTED, WITH THE ULTIMATE GOAL TO UNRAVEL POTENTIAL PATHOPHYSIOLOGICAL MECHANISMS THAT MAY BE EXPLORED, IN A NEAR FUTURE, AS PERSONALIZED DISEASE-MODIFYING THERAPEUTIC APPROACHES. 2019