1 3181 84 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 2 5919 36 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 3 3596 38 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 4 4379 39 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 5 182 33 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 6 4663 31 NEW HORIZONS: NOVEL APPROACHES TO ENHANCE HEALTHSPAN THROUGH TARGETING CELLULAR SENESCENCE AND RELATED AGING MECHANISMS. THE ELDERLY POPULATION IS INCREASING FASTER THAN OTHER SEGMENTS OF THE POPULATION THROUGHOUT THE WORLD. AGE IS THE LEADING PREDICTOR FOR MOST CHRONIC DISEASES AND DISORDERS, MULTIMORBIDITY, GERIATRIC SYNDROMES, AND IMPAIRED ABILITY TO RECOVER FROM ACCIDENTS OR ILLNESSES. ENHANCING THE DURATION OF HEALTH AND INDEPENDENCE, TERMED HEALTHSPAN, WOULD BE MORE DESIRABLE THAN EXTENDING LIFESPAN MERELY BY PROLONGING THE PERIOD OF MORBIDITY TOWARD THE END OF LIFE. THE GEROSCIENCE HYPOTHESIS POSITS THAT HEALTHSPAN CAN BE EXTENDED BY TARGETING FUNDAMENTAL AGING MECHANISMS, RATHER THAN ATTEMPTING TO ADDRESS EACH AGE-RELATED DISEASE ONE AT A TIME, ONLY SO THE AFFLICTED INDIVIDUAL SURVIVES DISABLED AND DIES SHORTLY AFTERWARD OF ANOTHER AGE-RELATED DISEASE. THESE FUNDAMENTAL AGING MECHANISMS INCLUDE, AMONG OTHERS, CHRONIC INFLAMMATION, FIBROSIS, STEM CELL/ PROGENITOR DYSFUNCTION, DNA DAMAGE, EPIGENETIC CHANGES, METABOLIC SHIFTS, DESTRUCTIVE METABOLITE GENERATION, MITOCHONDRIAL DYSFUNCTION, MISFOLDED OR AGGREGATED PROTEIN ACCUMULATION, AND CELLULAR SENESCENCE. THESE PROCESSES APPEAR TO BE TIGHTLY INTERLINKED, AS TARGETING ANY ONE APPEARS TO AFFECT MANY OF THE REST, UNDERLYING OUR UNITARY THEORY OF FUNDAMENTAL AGING MECHANISMS. INTERVENTIONS TARGETING MANY FUNDAMENTAL AGING PROCESSES ARE BEING DEVELOPED, INCLUDING DIETARY MANIPULATIONS, METFORMIN, MTOR (MECHANISTIC TARGET OF RAPAMYCIN) INHIBITORS, AND SENOLYTICS, WHICH ARE IN EARLY HUMAN TRIALS. THESE INTERVENTIONS COULD LEAD TO GREATER HEALTHSPAN BENEFITS THAN TREATING AGE-RELATED DISEASES ONE AT A TIME. TO ILLUSTRATE THESE POINTS, WE FOCUS ON CELLULAR SENESCENCE AND THERAPIES IN DEVELOPMENT TO TARGET SENESCENT CELLS. COMBINING INTERVENTIONS TARGETING AGING MECHANISMS WITH DISEASE-SPECIFIC DRUGS COULD RESULT IN MORE THAN ADDITIVE BENEFITS FOR CURRENTLY DIFFICULT-TO-TREAT OR INTRACTABLE DISEASES. MORE RESEARCH ATTENTION NEEDS TO BE DEVOTED TO TARGETING FUNDAMENTAL AGING PROCESSES. 2021 7 290 37 AGING AND PULMONARY FIBROSIS. IDIOPATHIC PULMONARY FIBROSIS IS A CHRONIC, PROGRESSIVE, AND USUALLY FATAL LUNG DISORDER OF UNKNOWN ETIOLOGY. THE DISEASE LIKELY RESULTS FROM THE INTERACTION OF GENETIC SUSCEPTIBILITY ARCHITECTURE, ENVIRONMENTAL FACTORS SUCH AS SMOKING, AND AN ABNORMAL EPIGENETIC REPROGRAMMING THAT LEADS TO A COMPLEX PATHOGENESIS. IDIOPATHIC PULMONARY FIBROSIS OCCURS IN MIDDLE-AGED AND MAINLY ELDERLY ADULTS, AND IN THIS CONTEXT AGE HAS EMERGED AS ITS STRONGEST RISK FACTOR. HOWEVER, THE MECHANISMS LINKING IT TO AGING ARE UNCERTAIN. RECENTLY, NINE MOLECULAR AND CELLULAR HALLMARKS OF AGING HAVE BEEN PROPOSED: GENOMIC INSTABILITY, TELOMERE ATTRITION, EPIGENETIC ALTERATIONS, LOSS OF PROTEOSTASIS, DEREGULATED NUTRIENT SENSING, MITOCHONDRIAL DYSFUNCTION, CELLULAR SENESCENCE, STEM CELL EXHAUSTION, AND ALTERED INTERCELLULAR COMMUNICATION. IN THIS REVIEW, WE PROVIDE AN OVERVIEW OF THESE MOLECULAR MECHANISMS AND THEIR INVOLVEMENT IN THE PATHOGENESIS OF IDIOPATHIC PULMONARY FIBROSIS, WHILE EMPHASIZING THAT THE STUDIES ON THIS DISEASE ARE FEW AND THE FINDINGS ARE NOT DEFINITIVE. 2016 8 285 30 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 9 5945 36 TARGETING THE "HALLMARKS OF AGING" TO SLOW AGING AND TREAT AGE-RELATED DISEASE: FACT OR FICTION? AGING IS A MAJOR RISK FACTOR FOR A NUMBER OF CHRONIC DISEASES, INCLUDING NEURODEGENERATIVE AND CEREBROVASCULAR DISORDERS. AGING PROCESSES HAVE THEREFORE BEEN DISCUSSED AS POTENTIAL TARGETS FOR THE DEVELOPMENT OF NOVEL AND BROADLY EFFECTIVE PREVENTATIVES OR THERAPEUTICS FOR AGE-RELATED DISEASES, INCLUDING THOSE AFFECTING THE BRAIN. MECHANISMS THOUGHT TO CONTRIBUTE TO AGING HAVE BEEN SUMMARIZED UNDER THE TERM THE "HALLMARKS OF AGING" AND INCLUDE A LOSS OF PROTEOSTASIS, MITOCHONDRIAL DYSFUNCTION, ALTERED NUTRIENT SENSING, TELOMERE ATTRITION, GENOMIC INSTABILITY, CELLULAR SENESCENCE, STEM CELL EXHAUSTION, EPIGENETIC ALTERATIONS AND ALTERED INTERCELLULAR COMMUNICATION. WE HERE EXAMINE KEY CLAIMS ABOUT THE "HALLMARKS OF AGING". OUR ANALYSIS REVEALS IMPORTANT WEAKNESSES THAT PRECLUDE STRONG AND DEFINITIVE CONCLUSIONS CONCERNING A POSSIBLE ROLE OF THESE PROCESSES IN SHAPING ORGANISMAL AGING RATE. SIGNIFICANT AMBIGUITY ARISES FROM THE OVERRELIANCE ON LIFESPAN AS A PROXY MARKER FOR AGING, THE USE OF MODELS WITH UNCLEAR RELEVANCE FOR ORGANISMAL AGING, AND THE USE OF STUDY DESIGNS THAT DO NOT ALLOW TO PROPERLY ESTIMATE INTERVENTION EFFECTS ON AGING RATE. WE ALSO DISCUSS FUTURE RESEARCH DIRECTIONS THAT SHOULD BE TAKEN TO CLARIFY IF AND TO WHAT EXTENT PUTATIVE AGING REGULATORS DO IN FACT INTERACT WITH AGING. THESE INCLUDE MULTIDIMENSIONAL ANALYTICAL FRAMEWORKS AS WELL AS DESIGNS THAT FACILITATE THE PROPER ASSESSMENT OF INTERVENTION EFFECTS ON AGING RATE. 2023 10 6412 47 THE SPECTRUM OF FUNDAMENTAL BASIC SCIENCE DISCOVERIES CONTRIBUTING TO ORGANISMAL AGING. AGING RESEARCH HAS UNDERGONE UNPRECEDENTED ADVANCES AT AN ACCELERATING RATE IN RECENT YEARS, LEADING TO EXCITEMENT IN THE FIELD AS WELL AS OPPORTUNITIES FOR IMAGINATION AND INNOVATION. NOVEL INSIGHTS INDICATE THAT, RATHER THAN RESULTING FROM A PREPROGRAMMED SERIES OF EVENTS, THE AGING PROCESS IS PREDOMINANTLY DRIVEN BY FUNDAMENTAL NON-ADAPTIVE MECHANISMS THAT ARE INTERCONNECTED, LINKED, AND OVERLAP. TO VARYING DEGREES, THESE MECHANISMS ALSO MANIFEST WITH AGING IN BONE WHERE THEY CAUSE SKELETAL FRAGILITY. BECAUSE THESE MECHANISMS OF AGING CAN BE MANIPULATED, IT MIGHT BE POSSIBLE TO SLOW, DELAY, OR ALLEVIATE MULTIPLE AGE-RELATED DISEASES AND THEIR COMPLICATIONS BY TARGETING CONSERVED GENETIC SIGNALING PATHWAYS, CONTROLLED FUNCTIONAL NETWORKS, AND BASIC BIOCHEMICAL PROCESSES. INDEED, FINDINGS IN VARIOUS MAMMALIAN SPECIES SUGGEST THAT TARGETING FUNDAMENTAL AGING MECHANISMS (EG, VIA EITHER LOSS-OF-FUNCTION OR GAIN-OF-FUNCTION MUTATIONS OR ADMINISTRATION OF PHARMACOLOGICAL THERAPIES) CAN EXTEND HEALTHSPAN; IE, THE HEALTHY PERIOD OF LIFE FREE OF CHRONIC DISEASES. IN THIS REVIEW, WE SUMMARIZE THE EVIDENCE SUPPORTING THE ROLE OF THE SPECTRUM OF FUNDAMENTAL BASIC SCIENCE DISCOVERIES CONTRIBUTING TO ORGANISMAL AGING, WITH EMPHASIS ON MAMMALIAN STUDIES AND IN PARTICULAR AGING MECHANISMS IN BONE THAT DRIVE SKELETAL FRAGILITY. THESE MECHANISMS OR AGING 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. BECAUSE THESE MECHANISMS ARE LINKED, INTERVENTIONS THAT AMELIORATE ONE HALLMARK CAN IN THEORY AMELIORATE OTHERS. IN THE FIELD OF BONE AND MINERAL RESEARCH, CURRENT CHALLENGES INCLUDE DEFINING THE RELATIVE CONTRIBUTIONS OF EACH AGING HALLMARK TO THE NATURAL SKELETAL AGING PROCESS, BETTER UNDERSTANDING THE COMPLEX INTERCONNECTIONS AMONG THE HALLMARKS, AND IDENTIFYING THE MOST EFFECTIVE THERAPEUTIC STRATEGIES TO SAFELY TARGET MULTIPLE HALLMARKS. BASED ON THEIR INTERCONNECTIONS, IT MAY BE FEASIBLE TO SIMULTANEOUSLY INTERFERE WITH SEVERAL FUNDAMENTAL AGING MECHANISMS TO ALLEVIATE A WIDE SPECTRUM OF AGE-RELATED CHRONIC DISEASES, INCLUDING OSTEOPOROSIS. (C) 2018 AMERICAN SOCIETY FOR BONE AND MINERAL RESEARCH. 2018 11 292 34 AGING AND SUSCEPTIBILITY TO PULMONARY DISEASE. THE LUNGS ARE CONTINUALLY SUBJECTED TO NOXIOUS AND INERT SUBSTANCES, ARE IMMUNOLOGICALLY ACTIVE, AND ARE IN A CONSTANT STATE OF DAMAGE AND REPAIR. THIS MAKES THE PULMONARY SYSTEM PARTICULARLY VULNERABLE TO DISEASES OF AGING. AGING CAN BE UNDERSTOOD AS RANDOM MOLECULAR DAMAGE THAT IS UNREPAIRED AND ACCUMULATES OVER TIME, RESULTING IN CELLULAR DEFECTS AND TISSUE DYSFUNCTION. THE BREAKDOWN OF CELLULAR MECHANISMS, INCLUDING STEM CELL EXHAUSTION, GENOMIC INSTABILITY, TELOMERE ATTRITION, EPIGENETIC ALTERATION, LOSS OF PROTEOSTASIS, DEREGULATED NUTRIENT SENSING, MITOCHONDRIAL DYSFUNCTION, CELLULAR SENESCENCE, ALTERED INTERCELLULAR COMMUNICATION, AND CHANGES IN THE EXTRACELLULAR MATRIX IS THOUGHT TO ADVANCE THE AGING PROCESS ITSELF. CHRONIC OBSTRUCTIVE PULMONARY DISEASE (COPD), IDIOPATHIC PULMONARY FIBROSIS (IPF), AND CANCERS ILLUSTRATE A PATHOLOGIC BREAKDOWN IN THESE MECHANISMS BEYOND NORMAL AGING. THE IMMUNE SYSTEM BECOMES LESS EFFECTIVE WITH ADVANCING AGE. THERE IS A LOW-LEVEL STATE OF CHRONIC INFLAMMATION TERMED INFLAMMAGING WHICH IS THOUGHT TO BE DRIVEN BY IMMUNOSENESCENCE, THE CHANGES IN THE INNATE AND ADAPTIVE IMMUNE SYSTEMS WITH ADVANCING AGE THAT LEAD TO DYSREGULATION AND DECREASED EFFECTIVENESS OF THE IMMUNE SYSTEM. THESE PROCESSES OF AGING LEAD TO EXPECTED CHANGES IN THE FORM AND FUNCTION OF THE RESPIRATORY SYSTEM, MOST NOTABLY A LOSS OF LUNG ELASTICITY, DECREASE IN RESPIRATORY MUSCLE STRENGTH, INCREASE IN VENTILATION-PERFUSION MISMATCHING, AND STIFFENING OF THE VASCULATURE. THE ASTUTE CLINICIAN IS AWARE OF THESE EXPECTED FINDINGS AND DOES NOT OFTEN ATTRIBUTE DYSPNEA TO AGING ALONE. MAINTAINING A LOW THRESHOLD TO INVESTIGATE FOR COMORBID DISEASE AND UNDERSTANDING HOW PULMONARY DISEASE PRESENTS DIFFERENTLY IN THE ELDERLY THAN IN YOUNGER ADULTS CAN IMPROVE CLINICAL OUTCOMES. (C) 2022 AMERICAN PHYSIOLOGICAL SOCIETY. COMPR PHYSIOL 12:3509-3522, 2022. 2022 12 2723 21 EXOSOMES: NOMENCLATURE, ISOLATION, AND BIOLOGICAL ROLES IN LIVER DISEASES. THE BIOGENESIS AND BIOLOGICAL ROLES OF EXTRACELLULAR VESICLES (EVS) IN THE PROGRESSION OF LIVER DISEASES HAVE ATTRACTED CONSIDERABLE ATTENTION IN RECENT YEARS. EVS ARE MEMBRANE-BOUND NANOSIZED VESICLES FOUND IN DIFFERENT TYPES OF BODY FLUIDS AND CONTAIN VARIOUS BIOACTIVE MATERIALS, INCLUDING PROTEINS, LIPIDS, NUCLEIC ACIDS, AND MITOCHONDRIAL DNA. BASED ON THEIR ORIGIN AND BIOGENESIS, EVS CAN BE CLASSIFIED AS APOPTOTIC BODIES, MICROVESICLES, AND EXOSOMES. AMONG THESE, EXOSOMES ARE THE SMALLEST EVS (30-150 NM IN DIAMETER), WHICH PLAY A SIGNIFICANT ROLE IN CELL-TO-CELL COMMUNICATION AND EPIGENETIC REGULATION. MOREOVER, EXOSOMAL CONTENT ANALYSIS CAN REVEAL THE FUNCTIONAL STATE OF THE PARENTAL CELL. THEREFORE, EXOSOMES CAN BE APPLIED TO VARIOUS PURPOSES, INCLUDING DISEASE DIAGNOSIS AND TREATMENT, DRUG DELIVERY, CELL-FREE VACCINES, AND REGENERATIVE MEDICINE. HOWEVER, EXOSOME-RELATED RESEARCH FACES TWO MAJOR LIMITATIONS: ISOLATION OF EXOSOMES WITH HIGH YIELD AND PURITY AND DISTINCTION OF EXOSOMES FROM OTHER EVS (ESPECIALLY MICROVESICLES). NO STANDARDIZED EXOSOME ISOLATION METHOD HAS BEEN ESTABLISHED TO DATE; HOWEVER, VARIOUS EXOSOME ISOLATION STRATEGIES HAVE BEEN PROPOSED TO INVESTIGATE THEIR BIOLOGICAL ROLES. EXOSOME-MEDIATED INTERCELLULAR COMMUNICATIONS ARE KNOWN TO BE INVOLVED IN ALCOHOLIC LIVER DISEASE AND NONALCOHOLIC FATTY LIVER DISEASE DEVELOPMENT. DAMAGED HEPATOCYTES OR NONPARENCHYMAL CELLS RELEASE LARGE NUMBERS OF EXOSOMES THAT PROMOTE THE PROGRESSION OF INFLAMMATION AND FIBROGENESIS THROUGH INTERACTIONS WITH NEIGHBORING CELLS. EXOSOMES ARE EXPECTED TO PROVIDE INSIGHT ON THE PROGRESSION OF LIVER DISEASE. HERE, WE REVIEW THE BIOGENESIS OF EXOSOMES, EXOSOME ISOLATION TECHNIQUES, AND BIOLOGICAL ROLES OF EXOSOMES IN ALCOHOLIC LIVER DISEASE AND NONALCOHOLIC FATTY LIVER DISEASE. 2023 13 5629 28 SENESCENCE IN COPD AND ITS COMORBIDITIES. CHRONIC OBSTRUCTIVE PULMONARY DISEASE (COPD) IS REGARDED AS A DISEASE OF ACCELERATED LUNG AGING. THIS AFFLICTION SHOWS ALL OF THE HALLMARKS OF AGING, INCLUDING TELOMERE SHORTENING, CELLULAR SENESCENCE, ACTIVATION OF PI3 KINASE-MTOR SIGNALING, IMPAIRED AUTOPHAGY, MITOCHONDRIAL DYSFUNCTION, STEM CELL EXHAUSTION, EPIGENETIC CHANGES, ABNORMAL MICRORNA PROFILES, IMMUNOSENESCENCE, AND A LOW-GRADE CHRONIC INFLAMMATION (INFLAMMAGING). MANY OF THESE PATHWAYS ARE DRIVEN BY CHRONIC EXOGENOUS AND ENDOGENOUS OXIDATIVE STRESS. THERE IS ALSO A REDUCTION IN ANTIAGING MOLECULES, SUCH AS SIRTUINS AND KLOTHO, WHICH FURTHER ACCELERATE THE AGING PROCESS. COPD IS ASSOCIATED WITH SEVERAL COMORBIDITIES (MULTIMORBIDITY), SUCH AS CARDIOVASCULAR AND METABOLIC DISEASES, THAT SHARE THE SAME PATHWAYS OF ACCELERATED AGING. UNDERSTANDING THESE MECHANISMS HAS HELPED IDENTIFY SEVERAL NOVEL THERAPEUTIC TARGETS, AND SEVERAL DRUGS AND DIETARY INTERVENTIONS ARE NOW IN DEVELOPMENT TO TREAT MULTIMORBIDITY. 2017 14 5630 39 SENESCENCE IN PULMONARY FIBROSIS: BETWEEN AGING AND EXPOSURE. TO DATE, CHRONIC PULMONARY PATHOLOGIES REPRESENT THE THIRD LEADING CAUSE OF DEATH IN THE ELDERLY POPULATION. EVIDENCE-BASED PROJECTIONS SUGGEST THAT >65 (YEARS OLD) INDIVIDUALS WILL ACCOUNT FOR APPROXIMATELY A QUARTER OF THE WORLD POPULATION BEFORE THE TURN OF THE CENTURY. GENOMIC INSTABILITY, TELOMERE ATTRITION, EPIGENETIC ALTERATIONS, LOSS OF PROTEOSTASIS, DEREGULATED NUTRIENT SENSING, MITOCHONDRIAL DYSFUNCTION, CELLULAR SENESCENCE, STEM CELL EXHAUSTION, AND ALTERED INTERCELLULAR COMMUNICATION, ARE DESCRIBED AS THE NINE "HALLMARKS" THAT GOVERN CELLULAR FITNESS. ANY DEVIATION FROM THE NORMAL PATTERN INITIATES A COMPLEX CASCADE OF EVENTS CULMINATING TO A DISEASE STATE. THIS BLUEPRINT, ORIGINALLY EMPLOYED TO DESCRIBE ABERRANT CHANGES IN CANCER CELLS, CAN BE ALSO USED TO DESCRIBE AGING AND FIBROSIS. PULMONARY FIBROSIS (PF) IS THE RESULT OF A PROGRESSIVE DECLINE IN INJURY RESOLUTION PROCESSES STEMMING FROM ENDOGENOUS (PHYSIOLOGICAL DECLINE OR SOMATIC MUTATIONS) OR EXOGENOUS STRESS. ENVIRONMENTAL, DIETARY OR OCCUPATIONAL EXPOSURE ACCELERATES THE PATHOGENESIS OF A SENESCENT PHENOTYPE BASED ON (1) WINDOW OF EXPOSURE; (2) DOSE, DURATION, RECURRENCE; AND (3) CELLS TYPE BEING TARGETED. AS THE LUNG AGES, THE THRESHOLD TO GENERATE AN IRREVERSIBLY SENESCENT PHENOTYPE IS LOWERED. HOWEVER, WE DO NOT HAVE SUFFICIENT KNOWLEDGE TO MAKE ACCURATE PREDICTIONS. IN THIS REVIEW, WE PROVIDE AN ASSESSMENT OF THE LITERATURE THAT INTERROGATES LUNG EPITHELIAL, MESENCHYMAL, AND IMMUNE SENESCENCE AT THE INTERSECTION OF AGING, ENVIRONMENTAL EXPOSURE AND PULMONARY FIBROSIS. 2020 15 5632 27 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 16 5525 34 RNA BINDING PROTEINS IN SENESCENCE: A POTENTIAL COMMON LINKER FOR AGE-RELATED DISEASES? AGING REPRESENTS THE MAJOR RISK FACTOR FOR THE ONSET AND/OR PROGRESSION OF VARIOUS DISORDERS INCLUDING NEURODEGENERATIVE DISEASES, METABOLIC DISORDERS, AND BONE-RELATED DEFECTS. AS THE AVERAGE AGE OF THE POPULATION IS PREDICTED TO EXPONENTIALLY INCREASE IN THE COMING YEARS, UNDERSTANDING THE MOLECULAR MECHANISMS UNDERLYING THE DEVELOPMENT OF AGING-RELATED DISEASES AND THE DISCOVERY OF NEW THERAPEUTIC APPROACHES REMAIN PIVOTAL. WELL-REPORTED HALLMARKS OF AGING ARE CELLULAR SENESCENCE, GENOME INSTABILITY, AUTOPHAGY IMPAIRMENT, MITOCHONDRIA DYSFUNCTION, DYSBIOSIS, TELOMERE ATTRITION, METABOLIC DYSREGULATION, EPIGENETIC ALTERATIONS, LOW-GRADE CHRONIC INFLAMMATION, STEM CELL EXHAUSTION, ALTERED CELL-TO-CELL COMMUNICATION AND IMPAIRED PROTEOSTASIS. WITH FEW EXCEPTIONS, HOWEVER, MANY OF THE MOLECULAR PLAYERS IMPLICATED WITHIN THESE PROCESSES AS WELL AS THEIR ROLE IN DISEASE DEVELOPMENT REMAIN LARGELY UNKNOWN. RNA BINDING PROTEINS (RBPS) ARE KNOWN TO REGULATE GENE EXPRESSION BY DICTATING AT POST-TRANSCRIPTIONAL LEVEL THE FATE OF NASCENT TRANSCRIPTS. THEIR ACTIVITY RANGES FROM DIRECTING PRIMARY MRNA MATURATION AND TRAFFICKING TO MODULATION OF TRANSCRIPT STABILITY AND/OR TRANSLATION. ACCUMULATING EVIDENCE HAS SHOWN THAT RBPS ARE EMERGING AS KEY REGULATORS OF AGING AND AGING-RELATED DISEASES, WITH THE POTENTIAL TO BECOME NEW DIAGNOSTIC AND THERAPEUTIC TOOLS TO PREVENT OR DELAY AGING PROCESSES. IN THIS REVIEW, WE SUMMARIZE THE ROLE OF RBPS IN PROMOTING CELLULAR SENESCENCE AND WE HIGHLIGHT THEIR DYSREGULATION IN THE PATHOGENESIS AND PROGRESSION OF THE MAIN AGING-RELATED DISEASES, WITH THE AIM OF ENCOURAGING FURTHER INVESTIGATIONS THAT WILL HELP TO BETTER DISCLOSE THIS NOVEL AND CAPTIVATING MOLECULAR SCENARIO. 2023 17 3922 30 LIPIDS AND THE HALLMARKS OF AGEING: FROM PATHOLOGY TO INTERVENTIONS. LIPIDS ARE CRITICAL STRUCTURAL AND FUNCTIONAL ARCHITECTS OF CELLULAR HOMEOSTASIS. CHANGE IN SYSTEMIC LIPID PROFILE IS A CLINICAL INDICATOR OF UNDERLYING METABOLIC PATHOLOGIES, AND EMERGING EVIDENCE IS NOW DEFINING NOVEL ROLES OF LIPIDS IN MODULATING ORGANISMAL AGEING. CHARACTERISTIC ALTERATIONS IN LIPID METABOLISM CORRELATE WITH AGE, AND IMPAIRED SYSTEMIC LIPID PROFILE CAN ALSO ACCELERATE THE DEVELOPMENT OF AGEING PHENOTYPE. THE PRESENT WORK PROVIDES A COMPREHENSIVE REVIEW OF THE EXTENT OF LIPIDS AS REGULATORS OF THE MODERN HALLMARKS OF AGEING VIZ., CELLULAR SENESCENCE, CHRONIC INFLAMMATION, GUT DYSBIOSIS, TELOMERE ATTRITION, GENOME INSTABILITY, PROTEOSTASIS AND AUTOPHAGY, EPIGENETIC ALTERATIONS, AND STEM CELLS DYSFUNCTIONS. CURRENT EVIDENCE ON THE MODULATION OF EACH OF THESE HALLMARKS HAS BEEN DISCUSSED WITH EMPHASIS ON INHERENT AGE-DEPENDENT DEFICIENCIES IN LIPID METABOLISM AS WELL AS EXOGENOUS LIPID CHANGES. THERE APPEARS TO BE SUFFICIENT EVIDENCE TO CONSIDER IMPAIRED LIPID METABOLISM AS KEY DRIVER OF THE AGEING PROCESS ALTHOUGH MUCH OF KNOWLEDGE IS YET FRAGMENTED. CONSIDERING DIETARY LIPIDS, THE TYPE AND QUANTITY OF LIPIDS IN THE DIET IS A SIGNIFICANT, BUT OFTEN OVERLOOKED DETERMINANT THAT GOVERNS THE EFFECTS OF LIPIDS ON AGEING. FURTHER RESEARCH USING INTEGRATIVE APPROACHES AMIDST THE KNOWN AGING HALLMARKS IS HIGHLY DESIRABLE FOR UNDERSTANDING THE THERAPEUTICS OF LIPIDS ASSOCIATED WITH AGEING. 2023 18 5322 27 PULMONARY DISEASES AND AGEING. CHRONIC OBSTRUCTIVE PULMONARY DISEASE (COPD) AND IDIOPATHIC PULMONARY FIBROSIS ARE REGARDED AS A DISEASES OF ACCELERATED LUNG AGEING AND SHOW ALL OF THE HALLMARKS OF AGEING, INCLUDING TELOMERE SHORTENING, CELLULAR SENESCENCE, ACTIVATION OF PI3 KINASE-MTOR SIGNALING, IMPAIRED AUTOPHAGY, MITOCHONDRIAL DYSFUNCTION, STEM CELL EXHAUSTION, EPIGENETIC CHANGES, ABNORMAL MICRORNA PROFILES, IMMUNOSENESCENCE AND A LOW GRADE CHRONIC INFLAMMATION DUE TO SENESCENCE-ASSOCIATED SECRETORY PHENOTYPE (SASP). MANY OF THESE AGEING MECHANISMS ARE DRIVEN BY EXOGENOUS AND ENDOGENOUS OXIDATIVE STRESS. THERE IS ALSO A REDUCTION IN ANTI-AGEING MOLECULES, SUCH AS SIRTUINS AND KLOTHO, WHICH FURTHER ACCELERATE THE AGEING PROCESS. UNDERSTANDING THESE MOLECULAR MECHANISMS HAS IDENTIFIED SEVERAL NOVEL THERAPEUTIC TARGETS AND SEVERAL DRUGS AND DIETARY INTERVENTIONS ARE NOW IN DEVELOPMENT TO TREAT CHRONIC LUNG DISEASE. 2019 19 293 33 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 20 763 28 CAUSES OF PULMONARY FIBROSIS IN THE ELDERLY. IDIOPATHIC PULMONARY FIBROSIS (IPF) IS THE MOST COMMON AND MOST LETHAL TYPE OF IDIOPATHIC INTERSTITIAL PNEUMONIA. IT IS A CHRONIC, AGING-ASSOCIATED LUNG DISEASE CHARACTERIZED BY FIBROTIC FOCI AND INFLAMMATORY INFILTRATES, WITH NO CURE AND VERY LIMITED THERAPEUTIC OPTIONS. ALTHOUGH ITS ETIOLOGY IS UNKNOWN, SEVERAL PATHOGENIC PATHWAYS HAVE BEEN DESCRIBED THAT COULD EXPLAIN THIS PROCESS, INVOLVING AGING, ENVIRONMENTAL FACTORS, GENOMIC INSTABILITY, LOSS OF PROTEOSTASIS, TELOMERE ATTRITION, EPIGENETIC CHANGES, MITOCHONDRIAL DYSFUNCTION, CELL SENESCENCE, AND ALTERED INTERCELLULAR COMMUNICATION. ONE OF THE MAIN PROGNOSTIC FACTORS FOR THE DEVELOPMENT OF IPF IN BROAD EPIDEMIOLOGICAL STUDIES IS AGE. THE INCIDENCE INCREASES WITH AGE, MAKING THIS A DISEASE THAT PREDOMINANTLY AFFECTS THE ELDERLY POPULATION, BEING EXCEPTIONAL UNDER 45 YEARS OF AGE. HOWEVER, THE DEGREE TO WHICH EACH OF THESE MECHANISMS IS INVOLVED IN THE ETIOLOGY OF THE UNCONTROLLED FIBROGENESIS THAT DEFINES IPF IS STILL UNKNOWN. CLARIFYING THESE QUESTIONS IS CRUCIAL TO THE DEVELOPMENT OF POINTS OF INTERVENTION IN THE PATHOGENESIS OF THE DISEASE. THIS REVIEW BRIEFLY SUMMARIZES WHAT IS KNOWN ABOUT EACH POSSIBLE ETIOLOGICAL FACTOR, AND THE QUESTIONS THAT MOST URGENTLY NEED TO BE ADDRESSED. 2018